Delft University of Technology
FACULTY MECHANICAL, MARITIME AND MATERIALS ENGINEERING
Department Marine and Transport Technology Mekelweg 2 2628 CD Delft the Netherlands Phone +31 (0)15-2782889 Fax +31 (0)15-2781397 www.mtt.tudelft.nl
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Specialization: Transport Engineering and Logistics
Report number: 2013.TEL.7753
Title:
Optimal spacing of flower bulbs
Author:
B. Aberkrom
Title (in Dutch) Optimale plaatsing van bloembollen
Assignment: Literature Confidential: no
Initiator (university): Prof. dr. ir. G. Lodewijks
Initiator (company): dir. J. Broersen (Gourmet BV, Grootebroek) Supervisor: dr. ir. Y. Pang
Delft University of Technology
FACULTY OF MECHANICAL, MARITIME AND MATERIALS ENGINEERING
Department of Marine and Transport Technology Mekelweg 2 2628 CD Delft the Netherlands Phone +31 (0)15-2782889 Fax +31 (0)15-2781397 www.mtt.tudelft.nl
Student: B. Aberkrom Assignment type: Literature
Supervisor (TUD): dr. ir. Y. Pang Creditpoints (EC): 10 Supervisor (Company) dir. J. Broersen Specialization: TEL
Report number: 2013.TEL.7753 Confidential: No
Subject: Optimal spacing of flower bulbs
An overview of existing mechanisms that would be able to help with separation and placing of flower bulbs to get an (almost) optimal plant spacing on the field as result.
Gourmet is specialized in the supply of highly qualified flower bulbs, one of the proudest symbols of the Netherlands. Many types of bulbs do not need precision planting and grow with an arbitrary spacing on the field. For the flower bulbs that do care there is no machine available jet that can provide that extra precision.
The literature assignment is intended to give an overview of existing mechanisms that could in any way be helpful in the design of a new precision planting machine for flower bulbs.
The mentor,
Summary
Gourmet B.V. is specialized in the cultivation, selection and packaging of shallots and other allium cultivars. Shallots are called flower bulbs in practice, a proud symbol of the Netherlands. The company continually works on the development and improvement of his processes. One of those processes is the planting of flower bulbs. In short, the goal is to go from drill planting to precision drill planting. That means that bulbs are planted arbitrary spaced in ploughed furrows on the field nowadays and Gourmet cultivates several particular type of bulbs of which the yield potential could be improved considerable with uniformity of plant spacing. Optimum spacing improve soil nutrition distribution and reduces shape deformities and losses due to skipping.
In order to do so, the cultivating equipment is in need of an upgrade. There is no machine available jet on the market that is able to plant flower bulbs with such precision on the land. Therefore Gourmet has asked the Technical University Delft to first provide a broad literature research on existing
mechanisms that could aid with any kind of precision planting and be used for a new planter design. On request, this assignment consists of research in many different industries besides agriculture. The problem is divided into two distinct parts. First, the mass flow type of feeding need to be changed to precise flow of bulbs and secondly the mechanized speed lead into dynamic motions of the bulbs which introduces the problematic seed roll. Therefore the research of mechanisms is subdivided in separation of individual bulbs and delivery of bulbs to the furrow. The latter being both placing and prevention of seed roll in the furrow. The mechanisms are subdivided into working principals which include conveying, rotating, pick and place and several miscellaneous types of equipment.
Conveyors guide in different directions and make use of speed differences or vibration to align articles in a line. In combination with pockets, cups, grippers or even screw, the articles get more individual separated or guided within processes. The rotating equipment come in many variants such as plates, disks, drums and types with mechanical or vacuum grippers. Several of these separate articles in a good and sufficient way. If used as a wheel then the placing could be precise and controlled. Pick and place mainly include robots which are lacking in speed but make up with their precision. The coupled mechanism can provide the capacity although they require more space. Furthermore, dispensers and shuffle feeders maintain a good separation feed of articles. Lastly several simple things like chutes, flaps and firmers can assist in the guiding of bulbs and furrow opening devices such as different shaped runners or punch openers can improve the prevention of seed roll.
Three mechanisms stand out with their performances and are recommended for an improved precision planter. The cup conveyor for its excellent separation, the wheel for probably the best and simplest placing mechanism and the screw conveyor as an alternative which is able to provide both separation and delivering but is easy to use in combination with the other mechanisms as well.
Summary (in Dutch)
Gourmet B.V. is gespecialiseerd op het gebied van de teelt, selectie en verpakking van sjalotten en andere allium varianten. Sjalotten worden ook wel bloembollen genoemd in the praktijk, een van de trotse symbolen van Nederland. Het bedrijf werkt continu aan de ontwikkeling en verbetering van zijn processen. Een van deze processen is het planten van bloembollen. Kort gezegd is het doel om van ‘drill planting’ naar ‘precision drill planting’ over te stappen. Dat wil zeggen dat op dit moment de bollen onregelmatig in een geul worden geplaatst en Gourmet wil enkele speciale type bloembollen optimaal gespreid in diezelfde geul gaan planten. Een meer optimale spreiding verhoogd de opbrengst aanzienlijk doordat de bollen geen voedingswaarden uit de grond meer hoeven te delen, het
verminderd vervormingen en verminderd verliezen door lege plekken in de geul.
Om tot een resultaat te komen heeft het bestaande materiaal een stevig herontwerp nodig. Er is tot op heden nog geen machine verkrijgbaar waarmee het mogelijk is om bloembollen met precisie op het land te planten. Daarom heeft Gourmet de Technische Universiteit Delft gevraagd om een literatuur onderzoek uit te voeren naar bestaande mechanismen die gebruikt zouden kunnen worden voor een nieuw ontwerp van een plantmachine. Op verzoek wordt het onderzoek erg breed gehouden en worden daarom buiten landbouw juist ook andere industrieën bekeken.
De oplossingen zijn verdeeld in twee aparte onderdelen. Ten eerste de ongecontroleerde toevoer zal moeten veranderen in precieze timing van individuele bollen. En ten tweede zijn de dynamische bewegingen een probleem omdat deze ervoor zorgen dat bloembollen gaan rollen wanneer ze de grond raken. Daarom is het onderzoek verdeeld in mechanismen die de bollen verenkelen en mechanismen die de bollen op de grond plaatsen. Een verdere onderverdeling is gemaakt naar de werking van elke techniek: transportbanden, puur draaiende mechanismen, ‘pick ’n place’ en enkele overige technieken.
Transportbanden geleiden bollen in verschillende richtingen en maken gebruik van trillingen en snelheidsverschillen om artikelen op een lijn te brengen. In combinatie met uithollingen, lepels, grijpers en zelfs wokkels of schroeven zijn artikelen beter individueel te verenkelen of te begeleiden. Roterende mechanismen komen in meerdere varianten voor en kunnen bestaan uit platen, schijven, trommels of combinaties met grijpers of vacuüm oplossingen. Meerdere varianten vormen heel degelijke verenkeling van artikelen, ook veel voorkomend in de landbouw. Als wiel kan het zorgen voor een precieze en gecontroleerde plaatsing van bollen. Onder ‘Pick ’n place’ vallen oplossingen als robots welke snelheid missen maar wel heel precies werken. Gekoppelde mechanismen hebben juist voldoende capaciteit maar zijn over het algemeen grote machines. ‘Dispensers’ en ‘shuffle feeders’ zijn mechanismen die een goed kunnen verenkelen. En als laatste zijn er enkele simpele technieken zoals glijgoten, flappen en aandrukplaten die de bollen helpen te begeleiden en geul openers zoals speciaal gevormde ‘runners’ en ‘punch openers’ welke het rollen in de geul kunnen helpen tegen te gaan. Drie mechanismen vallen positief op met hun prestaties en worden aanbevolen voor een verbeterde plantmachine. De lepeltjesband levert een uitstekende verenkeling van artikelen. Een wiel zal waarschijnlijk de beste en simpelste techniek zijn om bloembollen op het land te plaatsen. En de schroef of wokkel maakt het mogelijk om zowel een goede verenkeling als plaatsing te verzorgen en is ook goed in combinatie te gebruiken met andere oplossingen.
Contents
Summary ... 3
Summary (in Dutch)... 4
1. Introduction ... 6 2. Problem explanation ... 7 Gourmet ... 7 Objective ... 8 3. Method of searching ... 11 Brainstorm ... 12 4. Mechanism categorization ... 13
5. Separating individual bulbs ... 15
5.1. Conveying ... 15 5.1.1. Belt conveyors ... 15 5.1.2. Bucket conveyors ... 19 5.1.3. Vibration conveyors ... 21 5.1.4. Screw conveyors ... 21 5.2. Rotation ... 22 5.2.1. Plate separation ... 22 5.2.2. Disc separation ... 23 5.2.3. Drum separation ... 24 5.2.4. Finger separation ... 24 5.2.5. Gripper separation ... 24 5.2.6. Vacuum separation ... 25 5.2.7. Miscellaneous ... 25
5.3. Pick and place ... 26
5.3.1. Robots ... 26 5.3.2. Coupled combinations ... 27 5.4. Miscellaneous ... 27 5.4.1. Dispensers ... 27 5.4.2. Shuffle feeder ... 28 5.4.3. Gravitation feeder ... 29 5.4.4. Flotation ... 29
6. Delivery of flower bulbs... 31
6.1. Conveying ... 31
6.1.1. Belt conveyors ... 31
6.1.2. Bucket conveyors ... 32
6.1.4. Screw conveyors ... 33
6.2. Rotation ... 34
6.3. Pick and place ... 35
6.4. Miscellaneous ... 36
6.4.1. Chutes ... 36
6.4.2. Flaps ... 37
6.4.3. Seed firmers ... 37
6.4.4. Attachments ... 37
7. Adaption of the furrow ... 39
7.1. Longitudinal axis ... 39
7.2. Lateral axis ... 40
1. Introduction
The plant population influences the degree of the yield and of course the profits. In practice, the needs of the individual plants have to be balanced against the requirement to maximize crop revenue. Agronomic trials have shown that the yield potential of many crop species is dependent on both the established population and the uniformity of spacing of plants within that population.
Many factors have to be considered when determining the optimum population and the spacing for a particular crop. The factors affecting potential yield include climatic conditions, time of planting, soil type and soil moisture status. All of which may have implications for crop growth, yield and harvest. Spacing of plants, within and between rows, is important as well. Many crops can tolerate reasonable variations in the uniformity of plant spacing without a loss in yield potential, provided the overall population is within the required range. With some crops, however, the yield potential can be improved with uniformity of plant spacing within the optimum population range.
Gourmet is a company who cultivates such particular type of flower bulbs that would profit from better spacing. In the past the better plant spacing would not justify the investment in new equipment. Nowadays there is no machine jet available that can provide any precision that places these bulbs within their optimum range. Therefore Gourmet has asked the Technical University Delft to assist in the search for a usable mechanism.
To do that, the research is divided into mechanisms that can separate individual flower bulbs and mechanisms that deliver each bulb with precision on the field. Both with a simple question: ‘What kind of mechanisms are available?’. Many machines process products in single file but what is it exactly that feeds the products? And is there actually a mechanism in use that prevent rolling after placing a sphere like object? It requires a broad research into any kind of industry or product to seek that one technique. In the ideal situation one that solves the complete problem.
Chapter 2 first describes more extensive what the research includes. It gives an impression of how the flower bulbs are planted nowadays, with which equipment it is done and all problems experienced with it. The manner of how the search for mechanism is taken is shortly indicated in chapter 3. The next chapter illustrates how the findings are categorized in different groups. The first groups being separation mechanisms in Chapter 5 which illustrates machines from conveyors to rotating equipment and robots. Just like in Chapter 6 where everything is about the delivering of bulbs to the ground. Lastly Chapter 7 closes the research with several extra remarks about adaption of the ground to see if there is something that could aid the placing of bulbs.
2. Problem explanation
The assignment starts with Gourmet. In its search for the best quality they would like a new machine that would help and improve their production. In order to do that, it would be practical to have a clear understanding of the objective and what it exactly is that needs that improvement.
Gourmet
Gourmet BV(Fig. 1) is a supplier specialized in the cultivation, selection and packing of shallots and other allium (onion and garlic family) cultivars such as dry garlic, fresh or green garlic, elephant garlic, white, sweet and red onions, baby onions and the most recent novelty Stoneleeks®. Due to
their planning of the production, in 19 countries around the world, they are able to deliver products of consistent good quality 365 days a year. Gourmet delivers their products in various types of packaging to consumers, wholesalers and greengrocers.
Fig. 1 Gourmet B.V.
Gourmet started out as a family-run business of the family Broersen and has been active in the cultivation and selection of shallots for three generations. In former years they provided planting stock to nurseries. Fifteen years ago, Gourmet branched out into the development of new cultivars
appropriate for the consumer market. Nowadays it delivers three types of cultivars in good quality the whole year through; Golden Gourmet®, Red Sun® and Springfield®. The company has been
operating under the name Gourmet since 1993. This name is derived from a particular shallot cultivar developed by the company and means "gastronome" or "connoisseur" in various languages. Together with his wife, Jan Broersen filled the first shallot dishes by hand. Now the company has 45 permanent employees and, after a recent expansion of business operations, eight modern packing lines. Gourmet expects their growth potential to continue in the future. This will be realized not only through the continued provision of the current range of good quality products, but also through the introduction of new products.
Gourmet fully understands that the safety and tracebility of foodstuffs is of great importance. Therefore, the company has been continually working on the development and improvement of his processes. This is demonstrated by the fact that Gourmet was the first Dutch organisation in the agricultural sector that was handed an official EurepGAP-certificate. Furthermore, they have BRC certification for some considerable time. Customers and consumers can be guaranteed that they can safely use the products of Gourmet.
EurepGAP represents the major market leaders of the European supermarket organisations and uses GAP (Good Agricultural Practice), as a framework for the verification of a safe and healthy production method. At the end of November 2000 Gourmet was the first organisation in the agricultural sector that was handed an official EurepGAP-certificate. After that they worked hard to get certified for the foreign onion- and garlic production and not without result; Gourmet is also the first organization that cultivates EurepGAP certified Chinese garlic.
During 2002 Gourmet gained the BRC certificate. BRC stands for British Retail Consortium and is issued by CBL (Dutch Central Bureau for Foods). Granting this certification implies amongst others that the production processes for the storage, packing and sale of unsliced shallots, onions and garlic meet the requirements for the 'foundation level' of the CBL/BRC code. This code includes that the control of food safety and quality risks of the line of products is guaranteed in accordance with the approved procedures and work instructions.
The Netherlands is worldwide known for its flowers. There are about 11.000 hectares cultivated with flower bulbs. They are vegetative propagated which means that a small flower bulb is planted around
August and a big bulb with an attached small bulb are harvested around July. The multiplication factor is important. This is the number of bulbs harvested per set. This factor is determined by the number of buds potentially present in the mother bulb. Large bulbs have a greater multiplication factor than small ones. The small harvested bulbs are used for a new cyclus.
Objective
This assignment is about shallots, also called flower bulbs in practice. They need to be put in the ground and if possible in the most optimal way. Nowadays the positioning is rather arbitrary and therefore Gourmet seeks a new mechanism to place flower bulbs on the fields. The planting depth is 2 centimeter below the surface and is done by dropping them in rows on the land. The rows are not the problem, it is the positioning within the rows which need improvement. The flower bulbs are dropped from a big hopper through smaller pipes into furrows. Afterwards the furrow is filled up with soil by disks or other means on the end of the machine (Fig. 2).
Fig. 2 Illustration of planting mechanism used nowadays
Plants should have optimum spacing in the ground as they mature. This reduces shape deformities caused by plant over-crowding when the seeds are planted too close together and makes sure that they don’t end up using the same nutrition’s from the soil. Off-size or off-shape bulbs are obviously unwanted and therefore it is important that the planted bulbs are placed in the ground with uniform spacing. Therefore the distance A is important and could use some improvement. This distance does not necessarily need to have a precision within millimeters, but with improved intervals the quality of the product will increase as well.
Particular combinations of populations, spacing requirements and placement methods give rise to distinct planting patterns [1]. The range of possible planting patterns used to describe the spatial orientation and placement of seeds planted in the field can be seen below (Fig. 3). Broadcast planting is typically used for flower bulbs. The drill planting technique is used at this moment by Gourmet with its randomly distribution in furrows. The reasonably accurate control over the planting rate nowadays fail to meet the goals of Gourmet. The mass flow type of feeding need to be changed to precise separation and delivery mechanisms in order to go towards precision drill planting. The result having every single bulb almost equidistant apart along the furrow. Dibble planters are generally used for smaller seeds. They are a bit different and place a seed or a number of seeds in discrete holes, rather than furrows, dug in the seedbed. If possible then it would prevent any form of seed roll and the inaccuracies that come with it.
At the same time it is important that a single bulb will be placed in every space that is allocated for it. If one is not planted where it should be, then that would mean a loss of production. The creation of blank or barren spots in the field where plants should have been planted are called planting skips. All of the costs for that unplanted acreage are still incurred, because things like irrigation, spraying and harvesting equipment cover all of the ground. Losses due to skipping but also due to deformities, therefore directly affect the bottom line in terms of profit. Even a small percentage in reduction in seed skipping will create very significant revenue increases. Evenly spaced cultivation makes that the harvest of commercial interesting bulbs will increase with up to 10 – 15% for all 11.000 hectares of
Fig. 3 The next three types of planting techniques which use furrows
Another way of improving planting performance relates to the physical dynamics of simply placing bulbs in a furrow at mechanized speeds. The existing planting machines have moving parts that take the bulbs at rest from a hopper and then drop them in a row on the ground. The tractor drives about 5 kilometer per hour (1,4 m/s) over the field. And the flower bulbs are placed about 10 cm from each other. That means 14 bulbs per second in each furrow. There is a good deal of dynamic motion during the planting process because of a combination of factors. In this case a quickly moving conveyor belt, along with the planter’s forward movement and irregular shapes of both the flower bulbs and the ground along the line. While a new planter can drop flower bulbs at precisely timed moments to create precise spacing from one bulb to the next in the ground, the reality is that they hit the ground with a certain velocity and momentum. These factors contribute to seed roll. Differences in the amount of roll causes some bulbs to be too close together and others to be too far apart. The end result is both plant crowding and skips at the same time.
Lastly there is another subject that involves the rotating of the flower bulbs (Fig. 5). The ideal positioning of each bulb is of course with the roots down and the tip on top, but this is difficult to solve mechanically along the whole process including the closing of the groove. Furthermore the different shapes of the bulbs increase the difficulty even more. Therefore this ideal result of every bulb as like placed by hand is accepted to be an utopia and any improvement will be a huge plus but not required for the project or research.
Fig. 4 The planter used nowadays
To get a good impression of the used machine above two pictures of the planter (Fig. 4) [2] and an American patent that comes close to its working principle [3]. And from this same impression it is clear that there is room for some improvement. Therefore this research on existing mechanisms, combined with some practical insights, is made which will provide the basis for an engineering
assignment. And as described above both solutions for the uniform spacing of individual bulbs and the reduction of arbitrary rolling bulbs in the furrow are sought.
Fig. 5 The bulbs which are planted
The main boundary conditions which hold for the result can be summed into the following list. The research contains only the search for existing mechanisms and conclusions
The result provides better positioning of flower bulbs on the field
The result should provide the same or better conditions of quality of flower bulbs The result can be operated with a tractor and stays within the practical dimension limits
3. Method of searching
The research dives into different industries looking for a solution. Existing automations, mechanisms and methods are used to find something suitable. Each industry is divided into a list of sectors, products or product ranges in order to get a feeling of where to find information. A small briefly summarized list can be seen below. For all the products and different subjects there will be tried to get a good amount of research in the processes. Mechanisms can be found in production processes itself but because the of the nature of the problem the movement of objects before, within, between and after processes is probably a lot more interesting.
Automotive, electrical and mechanical engineering industries: control systems, automated systems and robotic devices, materials handling systems, drives and dosing technoglogy, bulk material technology, dischargers, conveyors, feeders, assembly, mixing, production and construction of consumer goods
Biotechnology industry (Agricultural): Farming, planting, seeding, harvesting, cultivating, tilling, plowing, weeding, digging (fruit, vegetables, floriculture, mushrooms)
Food industry: Processing, sorting, quality checking and grading, packing, filling (fruit, vegetables, beverage, dairy, bakery, meat & poultry, candy, chocolate, chips, ice cream)
Pharmaceutical industry: Pressing, filling, counting, printing, labeling, packaging, blister and strip packaging, tube filling and sealing and quality control (Tablets and capsules)
Metrology and pre-packaging industry: Packing and packaging, handling and lifting, conveying, storage (Corrugated boxes, Honeycomb, bags, Foam Packaging Materials, Bulk bins, Shipping supplies, cans, drums, bottles)
Textile and clothing industry: Weaving, sowing, stitching, breading (Clothing, performs for composites, sport accessories)
Wood, paper and printing industry: Sawing, cutting and folding
There is also an opportunity to improvise and see what can be found about some particular solutions. On the next page 7 different figures are given (Fig. 6A-6G), intended to get a better understanding of the problem and more ways to find solutions.
Figures 6.A and 6.B show two solutions for placing the flower bulbs. The first being a repeating mechanism and the second a continuous mechanism. Figure A shows immediately that problems like grasping needs to be handled. Also the spacing of bulbs before the placing needs attention. Figure 6.B on the other hand might solve the separation of the bulbs and could even prevent rolling in the groove. For both solutions, the input seems to be difficult. Figure 6.C shows that solutions do not necessarily have to be complicated. Rolling or sliding might be a lot better than just dropping them. The destination could be more accurate here but the input which comes out of the hopper still needs a good amount of regulation.
The three following figures (6.D, 6.E and 6.F) illustrate some opportunities for preventing the problem of rolling bulbs when in the groove. A flap or a wheel which holds them mechanically in place or making better use of the soil for automatic spacing. Again more regulation of the input is necessary which shows the need for the research in separating.
The last figure 6.G illustrate that solutions should also be possible after the dropping the bulbs on the field. Observation and measurement can be used to rearrange them. Furthermore this figure illustrates that solutions could also make use of air pressure or any kind of flow and do not per definition need a mechanical method.
To get from this complete problem description to the research, a list with keywords is put together by use of these figures. The mechanical movement, flow and other general keywords are listed next to the figures below.
Furthermore, the main start will be made with the agricultural sector. That includes machines for growing plants and cultivations mechanisms which are use to prepare the land for crops or weeding. These fields are the most in common with the problem itself. Thereafter the other industries will be explored.
Brainstorm
KeywordsA
B
C
D
E
F
G
Fig. 6 Brainstorm solutions to start the research
General
action, activity, apparatus, component, creation, device, engine, equipment, gadget, gear, instrument, invention, machinery, machine, mechanism, method, motor, operation, process, structure, system, techniques, tool, workings, works
Placing
alter, deliver, direct, displace, drive, emplacement, excite, handle, locate, manipulate, move, movement, passage, relocate, shipment, traffic, transfer, translate, transport, travel, treat adhesion, block, bump, capture, carry, catch, circulate, direct, eject, fly, force, form, gather, get, grab, grasp, hook, hurl, lay, lift up, pass around, pick up, place, position, press, propel, pulse, push, put, reach out, receive, revolution, roll, rotate, round, set, set up, shake, shift, shove, snap, snatch, step, stick, stir, stop, squeeze, suck, swap, swing, take hold of, throw, thrust, touch, turn over, wheel, whirl,
blow, blast, fan, float, flow, flux, spray, stream
Separating
align, allocate, arrange, array, break apart, break up, classify, collect, cut off, determine, diffuse, dispel, disperse, disrupt, dissipate, distribute, divide, division, fan out, fragment, fragmentize, gap, gather, influence, interrupt,
intervene, mold, order, organize, part, propagate, rank, regulate, relation, scatter, segregation, shape, sort, split up, spread, spread out
amount, bulk, bunch, bundle, capacity, chain, club, cluster, collection,
combination, formation, groups, length, lines, pack, portion, rows, sections, sets, size, sum, spatial relation, total,
4. Mechanism categorization
At request of Gourmet the mechanisms are categorized in two main groups.
The first being the actual separation of flower bulbs. With functional requirements as o the predetermined output rate of about 14 bulbs per second,
o the required accuracy spacing to meet the planting pattern and o all that with minimal damage to the bulbs during the process.
The second category is the delivering of the bulbs to the furrow. The mechanism need to be capable of
o conveying the bulbs from the separation discharge point to the place on the ground, o maintain the spacing accuracy during the conveyance and
o enable the bulbs to be deposited on the soil surface in an appropriate manner
It is a given that it will be tractor-powered and there is no need to make subdivisions for the way it will be mounted etc. since this research is about the mechanism and not about the complete machine. Several different factors do get mentioned with each technique although they are not used to classify them into groups. Bulb quality before and after planting mainly related to possible damage for example. Performance of the mechanism even with different size bulbs is of course a factor which help decide the use of a particular technique but it is difficult to actually categorize the machines in performance. The same accounts for operating speed and planting depth control mechanisms. To still aim for a structured overview of all available mechanisms (Table 1) the two main groups are subdivided in four smaller groups: conveyors, rotational equipment, pick and place equipment and miscellaneous. Each describing a particular type of working principal and thus the main distinction in ways to displace articles.
Planting of flower bulbs
Separation of flower bulbs Delivery of flower bulbs
Conveying
Rotation
Pick and place
Miscellaneous
Adaption of the furrow
Belt conveyors Bucket conveyors Vibrating conveyors Screw conveyors Plate Disc Drum Finger Gripper Vacuum Miscellaneous Robots Coupled combinations Dispenser Shuffle feeder Gravitation feeder Flotation Conveying Rotation Pick and place
Miscellaneous Belt conveyors Bucket conveyors Screw conveyors Chutes Flaps Firmers Attachments Robots Longitudinal axis Lateral axis Wheels
Table 1 Categorization of mechanisms
Of course there are many other different categories of conveyors like gravity rollers, wire mesh conveyors, flexible conveyors, spiral conveyors and pneumatic conveyors but none of them stand out as good solutions in this case. Bucket conveyors could also be called chain conveyors in many designs although the idea is the same. Rotational equipment includes four typically used mechanism in seed planting and added to that are gripper and vacuum types which seems to be used in the agricultural industry as well, like potatoes. Pick and place speaks for itself and makes the three general groups complete.
However, next to the singulation of bulbs and the delivery systems there are several soil-engaging components (Fig. 7). Although all components affect the result when planting, most of them will not be included in the research. The first two and last three do not immediately provide function that concern the placement of bulbs. They relate more to environmental factors like soil quality, moisture and temperature and soil treatment before or after planting like Surface mulches, tillage, irrigation, etc. All important factors for planting and for expected results of the harvest but not interesting for this research.
Fig. 7 Several soil-engaging components
The soil and residue cutting device only enables removal of crop and weed residue directly over the row area and assists the furrow opener by disturbing hard soil layers. There are several types of disc coulters including plain, notched, bubble, ripple and wavee, all having their own cutting edge profile. Row preparation devices at their turn remove the residue and level the immediate row area to assist the planter’s furrow opening device. Different devices like blades, concave discs, finger wheels, finger harrows, horizontal discs, tine types and roller types aim to prepare the rows.
Seed covering devices make sure to transfer the soil back into the furrow to cover the bulbs, they help regulating the planting depth by providing more or less soil and they stabilize the flower bulb
environment. Different types include overthrowers, scraper plates, chains, concave discs, disc coulters, finger wheels, fingers, knifes, paddles and tines. They all transfer the soil in their own way but it is not known if the devices have effect on seed roll and if yes which type of device has an advantage over the others. Therefore this component is also left out of the research unless there would be a mechanism that hold the bulbs in place while covering them with soil.
The last two components for row specific and non-row specific seedbed firming cannot improve the spatial relations of the bulbs anymore. They do promote several good soil conditions for the bulbs to grow, the planting depth can be adjusted by compacting the loose soil and they level the field surface. Examples are presswheels, finger wheel types and coils. They can be inclined and staggered in the direction of travel.
The only two seriously considered devices which could improve the precision planting are the furrow openers and firming devices. Although there is no information found about which shape of furrow is particularly good for flower bulbs, there still are some conclusions that can be made for both the longitudinal and lateral axis.
The furrow opener maintains uniformity of depth along the furrow and tries to firm the base of the seedbed but avoids over-compaction that could restrict the root growth. At the same time it has to prevent soil from flowing back into the furrow before the bulbs are placed and promote the flow of soil back into the furrow thereafter. Chapter 7 will describe some mechanisms.
The firming device can firm the still uncovered bulbs into the furrow and thereby reduce the possibility for bouncing and rolling of the bulbs after initial contact with the soil. It can be seen as a addition to the delivering devices and therefore is mentioned in Chapter 6.
5. Separating individual bulbs
Many types of machines process articles one by one and, accordingly, it is necessary that the articles be supplied to these machines one at a time at regularly spaced intervals. Therefore, to efficiently supply articles to such machines, a feed mechanism must be capable of receiving quantities of articles in random formation. Such as you would assume when assembled in a group at the bottom of a supply chute, and then arrange the articles in single file. Most available machines however do not have a problem when skips occur which is definitely important for this problem. The separation of bulbs is the first step in a more precise planting mechanism. Separation can be in individual, lines or groups of bulbs.
The mechanism tends to get more difficult if the placing requires some sort of buffer arrangement of flower bulbs between the separation and delivering. The flow of them out of the hopper and while separating needs some sort of regulation or the result would end up with empty spots on the ground or bulbs overflowing the mechanism.
5.1. Conveying
Many solutions for transferring articles work with conveyors. They have the ability to pick up a large number of objects, multiple object at the same time or one after another, without jamming or slowing down. They can handle articles with size variances even at high speeds. Meaningful mechanism are subdivided between the belt, bucket, vibration and screw conveyor types.
5.1.1. Belt conveyors
It seems more then logically to begin with an actual available machine for this problem. It is an improvement of the used machine with better operation and supply regulation but not completely sufficient if compared to the goals mentioned above. The mechanism of the Wifo precision planter (Fig. 8) [4] consists of normal conveyor belts. A youtube video [5] illustrates this machine the best. For each row there are two belt conveyors next to each other and driven in the opposite directions. One is a small belt on which the flower bulbs form a line towards the exit point of the machine. The other is a wide belt which transport the bulbs towards the beginning of the first belt. With the help of a vibrating plate placed above the smaller belt, only one row of bulbs stay on it. The excess of bulbs which fall off are transported back with the bigger belt next to it. The result is a very fast moving straight line of bulbs before they are dropped on the field. This is a considerable improvement over the old machine on which there is no line but just a steady mass flow. Still this is not jet a real separation of each individual bulbs. It seems reasonable that small dividing walls on the belt will probably interrupt the process and create skips. Although this could be tested and maybe provide a serious solution for the separation of individual bulbs even at a sufficient speed. Also this mechanism can be put closer to the ground and therefore the arbitrary drop and momentum of the bulbs are reduced. Furthermore this machine is easy to operate, easy to adjust and has a high capacity: driving speed up to 7km per hour. This combination of two or more opposite driven belts is used often as buffering equipment know as accumulation feeders [6]. These often work without vibration plates though.
The same technique but with several improvements is used for the Structural potato planter from Miedema (Fig. 9, Fig. 10) [7], extensively described in a brochure [8]. The planting of potatoes is almost the same as that of flower bulbs. They only put them deeper into the ground with an entire bed of sand put on top of it and the seeds are planted with bigger intervals. Instead of wide belts for the feeding line and the return line it makes use of small strings. This system seems to have some of advantages. Each of the strings used as conveyor can move at different speeds, due to different size of pulleys or different drives. On top of that they are at different heights and have the possibility to be driven by pulleys that are mounted in different angles [9]. This improves the technique of making one line of seeds. Also because of the same strings it becomes possible to move with some kind of
mechanism in between so that each individual seed or bulb could be separated from the others within the line. The unique foam roller is said to ensures a even better plant spacing. The obvious drawback is that this mechanism runs at a slower speed then the Wifo precision planter.
Fig. 9 Illustration of the Miedema Structural potato planter
Fig. 10 Picture of the foam roller on the Miedema Structural potato planter
Next are belt conveyors that consists of belts that are driven in the same or different directions but not in the opposite directions. Two versions make use of belts that form a v-shape together (Fig. 11). The first is a solution where one belt moves a little bit faster than the other which results in a single line of articles that by itself tries to close the gaps between the articles. Just like the orange sorting machine from Olimpias [10]. This requires a steady and controlled input of articles as too many or too few will result in doubles or skips. This does not necessarily need to be in a v-shape, it could also be a sandwich conveyor. The second type creates a line of parts too but here it needs plates that hold the majority of the parts. The patent from K. Wedler and W. Uhl [11] gives a good impression of the technique. This system is mainly designed for the orientation of the objects but it separates them as well.
Fig. 11 Two versions of v-shaped belt conveyors
Another design has succeeding belts, each a bit faster driven than the last one. The high speed singulator from Applied Robotics (Fig. 12) [12] is one of them. They are aligned in a way that one line of objects is made. Since each belt following the last moves faster, it creates space between each part and so separating them from another. It will be difficult to prevent skips within the resulting output flow. The same mechanism however this time in a straight line is called the VersaFeed bulk feeder [13] and is manufactured by MGS Machine corporation.
Fig. 12 The high speed singulator from Applied Robotics
A variant on the drive of the belt conveyor is designed in an Egg Grader machine from GA Tecnologia [14]. This machine uses a belt that goes up and down in order to take eggs row by row into the grading process. The belt is either driven with non-circular pulleys, which seems unlikely, or the complete system, including belt, pulleys and drive, is moved up and down.
One of the designs of Precision Planting Inc. (Fig. 13) [15] shows a precision belt seed meter. The horizontal conveyor separates seeds straight from the bulk. The sandwich conveyor that follows should guide each part from the meter to the furrow. Notice that the sandwich conveyor must have the same speed for both belts because otherwise the spatial relations will changes the further downwards they go. The belt seed meter itself [16] is often used by the planting of smaller seeds. It is a fairly simple mechanism only consisting of sprocket wheels, a seed conveyor belt and a housing. The belt has pockets that will each take a single seed. The mechanism comes in more variants with for example more rows on the belt or additions like brushes [17] that assist the separation process and prevent doubles. The concept separates seeds in a really efficient way. In this case there is no need for extra mechanisms to control the flow.
Fig. 13 Precision belt meter and an illustration of the belt with pockets
For this system are many different belts each for different seeds but there are also a completely different type of belts (Fig. 14) [18]. Rubber belts with holes pick up individual seeds and carry them to the drop point. The rest of the system with the seed hopper above the belt stays the same. Individual seeds fall into the holes in the belt and are then carried to the rear edge of the base where they are released. A wheel at the rear edge of the base helps force the seeds out of the belt holes.
Fig. 14 Precision belt meter and an illustration of the belt with holes
The poultry industry has several significant automated machines in use which all have interesting mechanisms. Often there are guiding plates on belts that try to form a steady flow of eggs onto separate conveyor rows. A youtube video of the Egg Grader from Yamasa [19], model 108,000 egg per hour, illustrates this technique in two ways. At 1:40 min a fast conveyor supplies eggs to a slower conveyor. The eggs divide themselves naturally between the rows with some help from the speed difference and some space that acts as a buffer. The result is a excellent separation however with many skips. This process is again illustrated in an American patent (Fig. 15) [20]. At 4:04 min about the same happens but the second conveyor only moves forward when there is an egg at every spot to prevent any possibility at skips. However, this prevents the flow from staying continuous.
The follow up could be with a conveyor that separates the lines from each other. This method for distributing and feeding eggs (Fig. 16) [21] consists of a conveyor with bars on which slidable lines are mounted. Guide rails below the carrying run of the conveyor provide a separate path for each line.
Fig. 16 Egg separation and positioning conveyor
5.1.2. Bucket conveyors
Next to the belt types of conveyors above there are many companies who provide systems with vertical bucket conveyors, for especially the planting of potato seeds like the machines from Miedema [22]. One of the major improvements over most mechanisms mentioned up till now is that bucket conveyors do separate each individual article instead of making rows or groups. A belt or chain with cups take seeds, bulbs or other objects out of a pick-up chamber. Each object is taken in a cup and goes along the belt over the top, guided to the bottom and is then dropped. It is easy to adjust the cups so it can handle all kind of shapes. Furthermore this system creates a short drop distance which assures the best spacing accuracy seen in available by planting machines.
After aditional research an actual flowerbulb planter came up that makes use of this mechanism. The result of the ATH/Nobels plantmachine (Fig. 17, Fig. 18) [23] is astonishing although a little slower than ideal as can be seen at youtube [24]. This machine uses a technique to throw soil over the seedbed instead of making furrows and closing them. It should not have any impact on the actual separation but it does allow us to see the result and a positive one at that.
Fig. 17 ATH / Nobels plantmachine type overschieter 2009
Each system has its own details like the Gimme GL cup version [25]. Larger diameter upper pulley to ensure a positive drive and safe delivery and better belt guiding. Guiding ribs behind the belt which ensure a reliable alignment. Smaller belt pulley at the bottom to guarantee a fast opening and therefore a better delivery in the furrow. Cleaning solutions to avoid dirt building up in front of and behind the cups. And mechanical vibration systems behind the belt that reduce doubles in the cups. There are many patents for this kind of machines including mechanisms that have interesting
variations in the design and are used for other applications and industries like circular containers [26]. There are also designs which try to improve this mechanism with the use of different cups that decrease the amount of skips. Examples are the Wifo planters, the older model 8400 Spudnik planters (Fig. 19) [27] and others [28] [29].
Fig. 19 Older Model 8400 planter from Spudnik
Another design of cups account for the orientation of the seeds [30]. This bucket conveyor from T. L. Snipes and B. L. Heston include a seed-intercepting pocket structure on the underside of the cups which receive and orientate the seed before releasing them into the furrow. The cups are shaped to efficiently receive cylindrical as well as round and oval seeds of different sizes.
A different singulator uses a bucket conveyor in combination with a normal belt conveyor. Total Systems has put the two type of conveyors perpendicular on top of each other (Fig. 20) [31]. The result is separation of each individual flower bulb however not in a organized way.
Fig. 20 Singulator of two perpendicular conveyors
The bucket conveyor design improves the possibility to feed articles into the next mechanism as well. For example the machine form Bella Viva Orchards [32] that slices apricots in two after separating them with a bucket conveyor. Furthermore there are gripper like versions as well, both vertically [33] and horizontally like the Egg Grader from Yamasa from reference 19 mentioned above but these are more interesting for delivery than for separation.
5.1.3. Vibration conveyors
Vibrating conveyors are used a lot when objects need to be taken out of a hopper or something similar, especially for bulk solid materials. But they are also used for bringing the material in one line. The very first mechanism mentioned, the Wifo precision planter, already worked with the help of vibration. However the majority of the vibrating conveyors work without belts. They come in different variations like bowls (Fig. 21) [34], plates [35], v-shaped feeders (Fig. 22) [36] and more. By vibrating they force parts to move up on a track. The track can even be designed to sort and orient the parts in consistent, repeatable positions. In bowls there are often arrangements that prevent the parts from reaching the output when they have the wrong orientation. V-shaped feeders can have some
arrangements as well. Static designs like walls that prevent doubles or moving components like plates that act as valves in the fruit and vegetable packaging equipment from Thorpack [37]. The track length, width, and depth have to be carefully chosen to suit the application and component shape and size. By adjusting the speed of vibration the flow of parts can be controlled and close gaps within the flow. The downside of this mechanism will probably be the speed which is generally slower than 14 objects per second.
Fig. 21 Bowl vibration feeder
Fig. 22 V-shaped vibration feeder
Another solution which Air Draulic Engineering designed for donuts include a normal conveyor that takes rows of donuts one by one out of the feeder [38]. It shows that vibrating conveyors can handle different kind of shapes and even sticky articles. The combination of vibrating and belt conveyor make an impressive separator.
5.1.4. Screw conveyors
The mechanism of the Lelieverenkelaar from SchoutenBercomex B.V. (Fig. 23) [39] consists of several components and one of them is a set of screw conveyors. It illustrates the potential really well for separation of articles. A steady feed of flower bulbs come in lines onto two screws for each line. The screws take each bulb apart with the blades and even adjust the spatial relation between them due to the tapered pitch. A nice application which makes use of screw conveyors with only one screw can be seen in the Langen's MC-SCA cartoner for lens solution kits [40]. The speed is easily adjusted and with the help of a conical shaft it is even possible to make them take articles straight from a hopper. There is also a patent for an entire potato planter which makes use of only screw conveyors [41]. Different kind of screws have been in use but most of them are specifically for mixing materials. The spiral version however is one that can be easily used for this kind of applications. The alignment of onions [42] is a good example, it actually orientates the articles as well.
Fig. 23 Lelieverenkelaar from SchoutenBercomex B.V.
5.2. Rotation
With all available solutions for the planting of seeds it is possible to make a distinction between different type of mechanisms. Literature divides them into two groups, mass flow seed metering devices and precision seed metering devices. Only the later is interesting since the first does not separate each individual seed but groups them together in a way that will not solve the problem. The precision seed metering devices include plate, disc, drum and finger type mechanisms. And when searching beyond only seeds there are types with grippers and solutions with vacuum as well. Of course these rotational separators are also used in different industries but most of them are based on the plate type separation especially for circular objects like cans, cigarettes, tubes and wires.
5.2.1. Plate separation
The plate type mechanisms consist of a rotating plate with pockets along the circumference. John Deere has an old patent for a potato planter (Fig. 24) [43]. Fitted between a frame is a double faced delivery wheel and on its opposite faces are a series of pockets having curved bottom walls. A pair of ejector wheels rotate together to discharge each potato out of its pocket. This mechanism has potential because of its simplicity. Only rotating equipment and no complicated things like grapping utilities within each pocket and ejection plungers to force the potato outward. The speed does not necessarily be the downside as is illustrated by a olive processing machine [44]. The main differences with this machine is a plate that is put horizontal and the articles are in the middle and on top of the plate instead of a external feed with the vertical plate. Inclined plates are also possible. Different articles can be handled with different pocket shapes. These are mechanical types with holes or cells around its periphery and a portion of the plate is exposed to seeds. If the hole or cell is of the appropriate size, a single articles will fall into it and will be separated, but there are air assisted and brush assisted [45] types as well.
5.2.2. Disc separation
The vacuum disc precision meters are probably used the most for the planting of seeds. It consists of a seed box and a rotating disc that has a row of holes around its circumference. It differs from the plate type in that the seeds do not fall into, nor pass through the hole and disc thickness plays no part. On one side of the disc vacuum makes sure that seeds stick to each hole on the other side of the disc so individual seeds can be separated. The pressure is released before the output point. The patent from E. Ribouleua illustrates this principle (Fig. 25) [46].
Fig. 25 Vacuum disk type precision seed meter
Even discs without holes or other mechanical way of securing items in place, are in use for some products as for example this eye drop filler machine in the pharmaceutical industry [47]. The main difference is the fact that the disc is now placed horizontally and the input comes from a belt
conveyor. Almost the same principle is used in the unique patented (Fig. 26) [48] planting system, the Koningsplanter [49], illustrated in a youtube video [50]. It has been especially designed for pre-sprouted potatoes, so these potatoes can be planted without sprout damage and what is more at high speed. It goes without saying that the machine is capable of planting other seeds and has high capacity and the capability of planting big sizes. There are even a few machines in operation planting onion bulbs for seed growing, so the concept is proven. Potatoes or bulbs travel towards the two conical formed discs with a flat outer rim. Alongside the wide conveyor belt there are two narrow conveyor belts, which are fed by the supply discs which counter rotate at a speed adjustable to that at which the machine is traveling over the field. The seed supplied by the conveyor belt are spread out by the rotating discs and picked up and carried to the narrow conveyor belts. The peripheral velocity of the discs is higher than the velocity of the conveyor belts, so that the seeds tend to crowd
together. In extension adjustable wall plates are positioned just above the conveyor belts. These plates vibrate which is the same principal as the Wifo precision planter mentioned above with reference 4.
5.2.3. Drum separation
Other mechanisms include pressurized air (Fig. 27) [51] in a lot of cases. The smaller type of seeds are forced to the inside wall or sucked on the outside wall of the drum. A good example of a drum with the articles on the outside wall is a machines for depositing nuts on candy bars [52]. Another design includes mechanical grippers [53] to hold each article in place. This potato planter from H. P. Baltzer is just a small drum to make a single line of potatoes but it holds them mechanically in place instead of the vacuum types. The same is done with the controlled feeding of cartridge cases [54], only pockets within the drum are enough to hold them in place instead of grippers.
Fig. 27 Seed drum
5.2.4. Finger separation
One of the mechanisms which make use of internal feed of seeds is the seed meter [55] from Precision planting Inc [56]. This design uses fingers with springs (Fig. 28) which provide consistent tension to hold each seed and separate it towards the tube for dropping on the land. In this case, the seeds are moved to the side of the wheel so that another mechanism can guide it towards the ground. This kind of design can achieve spacing accuracy of 97% or even more nowadays. Extra research has been done to reduce skips and doubles.
Fig. 28 Seed selection mechanism
5.2.5. Gripper separation
There are a lot more wheel like feeders for potato planters of which some use grippers, pins or something similar. One wheel [57] has pockets that have their walls forwardly inclined in the direction of rotation in order to pick them up in a better way. In each pocket is a retaining device for the
(Fig. 29) [58]. This is an old patent and unlikely to be efficient enough for the problem at hand but it does supply a separation of individual articles.
Fig. 29 Potato planter with grippers
The alternative version with pins is unlikely to use for flower bulbs as well. It selects individual seed by pinning them on the outside of a wheel. This mechanism is used a lot for potato planters and is illustrated on the website of Lockwood [59]. The video “We know potatoes Video – I” shows a working machine. The mechanism is better illustrated in a patent from P. M. Cronin [60]. The second half of the video however also illustrates the last technique as mentioned below.
5.2.6. Vacuum separation
One of the other mechanisms make use of pressurized air or vacuum and is used a lot for small seed meters and bigger articles like potatoes as well. In essence it is the same principle as the gripper separation only now without a mechanical way of securing articles in place. The Lockwood air cup planters (Fig. 30) [61] for example, better illustrated in a patent from L. L. Anderson [62]. Each arm with suction cups takes out a articles from the bulk and drops it afterwards on the ground. The arms are constructed in such a way that there will be no doubles.
An addition to the mechanism could be the combination of pressurized air and vacuum. That creates an opportunity for ejection of articles besides just releasing them. The internal ejection apparatus from C. L. Palmquist illustrates this fairly well [63].
Fig. 30 Lockwood Air Cup Planters
5.2.7. Miscellaneous
An extension to the vacuum type separator is included in a different planter mechanism [64]. Here again are arms which each have a suction cup, but the arm are variable in length which result in each cup being displaceable towards and away from the rotation axis to provide a variation in the velocity in dependence on its angular position. This could be a solution to give the mechanism more time to put a article in place and still place the same article with the required speed in the furrow. There is also a device that has a variable speed due to different rotation speed of each arm (Fig. 31) [65].
With the accelerating arms it is possible to achieve the required spatial relation. Another way for increasing the speed has been forseen in a combination of several meters and a conveyor [66].
Fig. 31 Device with variable speed
Other combinations of rotating equipment and conveyors include the fruit guiding apparatus from J. Albertoli (Fig. 32) [67]. It guides peach halves from a sorting table with two horizontal driven wheels. The idea consists of rubber sprocket-like wheels for a good grip on, and the prevention of damage to the articles. Or a cherry orientator which works in combination with a conveyor to separate and orientate each article [68]. This mechanism deserves the mention more due to a special technique for the orientation of each cherry but it still illustrates a separation device. A design worth a mention as well is one that combines a inclined plate type separator as well as belt conveyors and screw conveyors to guide and orientate pears [69].
Fig. 32 Fruit guiding apparatus
As last the MGS Machine Centrifugal bowl feeder [70]. This machine handles overwrapped products and is suitable for most pharmaceutical and food industries. Other then all previous mentioned rotating equipment makes this machine use of the centrifugal forces to separate the individual products.
5.3. Pick and place
Pick and place is an excellent method for precise handling of individual articles although more difficult with such high rate of product handling. Besides the standard robots there is also a subdivision for some of the more complicated machines which couple more techniques into one mechanism.
5.3.1. Robots
The Flex picker functions as both a singulator and placing mechanism. The FlexPickerTMIRB360 from ABB (Fig. 33) [71] is the “second generation” robot for pick and place applications. In youtube videos [72] is a good illustration of the speed given of both this robot and a similar concept [73]. Robots like this can move in many axis both lineair and rotational directions. Computer controlled movement is used together with cameras to pick up each article separately and deposit it where necessary. The Flex picker is a special tripod like design which create a faster operating speed. One that will not be as
Fig. 33 FlexPicker
5.3.2. Coupled combinations
Apart from the robots there are complicated systems, mostly combinations from different conveyors, rotational equipment, robots and other components all combined in a machine for a particular product. Two machines need to be noted since their speed and accuracie is of high standards. The first machine is an egg processing apparatus that at some point separates two rows of eggs at high speed from a conveyor to the next conveyor. This is done with a couple rotation mechanism which lift the complete row of eggs up to the conveyor that is stationed above it. In a youtube video the mechanism can be seen between 7:03 min and 9:06 min [74].
Secondly, MGS Machine Corporation designed a robotic pharmaceutical shuffle conveyor for dosing spoons [75]. Products are feed into a non-continuous bucket conveyor. One that accelerates and decelerates at fairly high speeds. Articles that miss a position in the bucket conveyor are fed back to the bulk and replaced by the next article to prevent any possibility at skips. After that it uses a robot for pick and place transfer of dosing spoons into continuous flights of a cartoner. Mainly a combination of succeeding conveyors plus a robot make this a serious solution for a continuous feed of articles at a good intermediate space. However, it needs a lot of space just for a single row of articles.
5.4. Miscellaneous
Four other types of mechanisms are difficult to subdivide in any of the previous groups. The first three make heavy use of gravity to separate individual articles. Primarily dispensers and shuffle feeders do however have good results for singulation compared many others that align them more in lines then truly separating them.
5.4.1. Dispensers
Dispensers in general consist of a stack of articles where they are taken away one by one, usually at the bottom of the stack. It is more difficult due to the different shapes of flower bulbs, they have a chance of getting stuck and cutting off the flow. A packing machinery (Fig. 34) [76] illustrates the mechanism with rotating equipment. Another design that makes use of stacks are the pick n’ place machines from MGS Machine Corporation [77].
Rather than a wheel this is done a lot with piston like designs as well [78]. This tablet encapsulator (Fig. 35) deposits a predetermined number of tablets into each of the hard gelatin capsules. A tablet carrier is reciprocated for a number of times during the capsule filling sequence so that with each reciprocation, each of the second guide holes receives a single tablet. In most cases the stack is formed only due to gravity but this machine uses vibration to keep the stack filled and flow smoothly. The speed of the design is however dependent on the gravity forces.
Fig. 35 Cross sectional view of a tablet encapsulator
MGS Machine Blister feeder module [79] illustrates a different technique to improve the flow of the stack instead of vibration. This machine feeds blisters at high speed into continuous moving flights of a wrapper or cartoner. The coming and going rotation driven equipment sees to a better discharge as well.
The last mechanism is actually a rational machine. It should have been somewhere in chapter 5.2 however it does not work without a stack of products. The PSA Rotary Placer (Fig. 36) [80] can handle up to 300 articles per minute. It has one rotating disc on which three rotating vacuum grippers do all the work.
Fig. 36 A rotary placer from Packaging Systems Automation Inc.
5.4.2. Shuffle feeder
are moved along the feeder in side-by-side relation and cannot be separated before they are discharged from the feeder. Some designs have taken care of that problem as well like the article feeder for pears [83] which make use of special shaped pockets. Another fruit feeder [84] shows that’s it is not necessary to use a lot of reciprocating members. With the help of rotating disks articles can also be fed in single file.
Fig. 37 Fruit shuffle feeder
5.4.3. Gravitation feeder
The design of a different feeder that brings parts in a straight line with the help of gravity is the Lelieverenkelaar from SchoutenBercomex B.V. mentioned before for its screw conveyors. This component comes first before the screws. It feeds flower bulbs in several transversely spaced lanes from a supply conveyor to the pick-up positions. The design includes several drums mounted in spaced and downwardly inclined relationships. The spacing between the adjacent drums is adapted for single objects and the inclination of the drums is sufficient to cause them to gravitate downwardly to the feeder pick-up positions. A push-pull drive mechanism is provided to pivot the drums back and forth about their axes of rotation to cause the parts to spin as they gravitate downwardly between the drums. Such spinning action facilitates rapid feeding and in particular prevents irregularly shaped parts from becoming stuck against each other to thereby interrupt their flow to the pick-up positions. The same mechanism is illustrated in a patent for separating fruit in a orange juice maker (Fig. 38) [85].
Fig. 38 Cross section of the Lelieverenkelaar SchoutenBercomex B.V.
5.4.4. Flotation
Although highly unlikely for a planter, it is also possible to use water in order to help separating or aligning articles. This is for example used in a Potato separator (Fig. 39) [86] where the bouncy transfer the potatoes to a belt conveyor. Blue Mountain Growers process almost 15 tons of fruit an hour due to pumped water within a sorting machine [87]. In combination with conveyors, rotating
equipment and a substantial amount of water that is pump around it separates cherries in lines. Flower bulbs float just like potatoes and fruit but this keeps being an unlikely mechanism in this case.
6. Delivery of flower bulbs
Proper and uniform spacing of flower bulbs in the furrow is essential to maximizing crop yield. New singulating mechanisms could be capable of planting in the field, however once the seed is dispensed from the mechanism various factors can operate on the seed which can affect the ultimate spacing in the furrow. So a new machine would need to do more then only take each single bulb apart. At some point the mechanism has to let go of the bulb after the transfer to the furrow and guiding to the correct spot. The seed roll is another factor that it need to take into account. The goal is to prevent any inaccuracies in the furrow.
6.1. Conveying
Just as with separation, the conveyors seem to be an important component in machines. The same type of groups can be found in existing machines although the vibratory type seems to be missing out. Belt, bucket and screw conveyors are capable of keeping the result from singulators and delivering that result to the furrow.
6.1.1. Belt conveyors
The Wifo potato planter described above, within the rotation disk section, has a conveyor sollution following up the separation process (Fig. 40, Fig. 41). A sandwich conveyor is used to maintain the regular row of potato seeds that come of the belt. A spiked roller conveys them to the furrow to be planted. The spatial relation will still be made at the small drop into the furrow although it is
considerable less than just dropping them. Furthermore the combination gives the bulbs more speed in the opposite direction of planting reducing the horizontal dynamic factors. A lot of planters for some reason throw the seeds, potatoes or bulbs forwards into the furrow. That together with the speed of machine itself increases the problem while it could cancel each other out like with this machine.
Fig. 40 A sideview of the Wifo Koningsplanter
Fig. 41 A rearview of the Wifo Koningsplanter
The illustration of a seed delivery apparatus (Fig. 42) [88] brings a new solution to deliver seeds. The mechanism has a conveyor like member that captures the seed from the meter to the lower outlet opening. The accompanied separator mechanism and the combination of the two is better illustrated in another patent [89]. The mechanism is particularly designed for the use of a sensor, it prevents
ambient light, dust and dirt from entering the housing. But it illustrates a nice way of directing the seeds to the ground instead of just dropping them. The bucket conveyors types for separation mentioned above solve this in a way as well but not only does this mechanism reduce the height significantly but it also redirects seeds to a more horizontal movement that reduces the probability for seed roll. Furthermore it secures the spatial relation between the seeds.
Fig. 42 Seed delivery apparatus
6.1.2. Bucket conveyors
The bucket conveyors as described before can easily move down to the furrow and reduce the drop height and even adjust dynamic motions and orientations when releasing. Therefore it is not only a profitable mechanism to separate flower bulbs but an improvement on the placing as well.
Cups and grippers differs from each other but the mechanism stays the same. So the picking and placing of articles can also be done with conveyor type mechanisms like the sorting equipment GeoSortIII [90]. This machine from Greefa checks the quality of fruit with a conveyor with grippers which pick and place each piece of fruit one by one. Just as the Egg Grader from Yamasa (Fig. 43) as mentioned above, although that moves egg at a bigger scale than the Greefa sorter does with fruit. Of course there are more and different kind of grippers on conveyors [91].
Fig. 43 Sideview of the Yamasa Egg Grader 108,000 eph
The same type of technique is illustrated by the patents from Hartness International Inc (Fig. 44) [92], both have different type of grippers [93]. The conveyor is used for milk bottles. It consists of connected links, each having a conveying surface and at least one movable gripping member. It includes a spring member urging the gripping members toward each other. In the concept it is loaded and unloaded at the bottom but the potential can be easily seen to put the flower bulbs in the
