The proposed of kinematic schemes was the first step of design. On the basis of the kinematic schemes the displacement, velocity and force characteristics have been determined. It allowed the selection of the appropriate drives of grippers. Then the parametric geometrical models in SolidWorks have been carried out and the static analyses have been conducted. The construction of simulation models in Matlab/Simulink environment was the last step of study.
Based on the carried out study it can be concluded that the designed jaws can be used in the light industry, where the reliable grip is important as well as the transferred elements have the circular cross section and small weight.
Furthermore the proposed jaws will be used in the manipulator mounted on the Mars rover build at the Technical University of Czestochowa.
Acknowledgement
The work has been carried out within statutory research of the Institute of Mechanics and Machine Design Foundations of Czestochowa University of Technology.
References
Bicchi A., Kumar V.: Robotic grasping and contact: A review, ICRA, 348-353.
Cekus D.: Modeling and simulation research of laboratory truck crane motion, Systems. Journal of Trandisciplinary Systems Science, Vol. 16, No 2, 96-103 (in Polish), 2012. Cekus D., Posiadała B., Waryś P.: Integration of modeling in SolidWorks and
Matlab/Simulink environments, Archive of Mechanical Engineering, Volume 61, Issue 1, 57–74, 2014.
Cekus D., Skrobek D., Waryś P.: Modeling and Simulation Research of 4 DOF Manipulator, Machine Dynamics Research, Vol. 38, No 1, 5-11, 2014.
Cutkosky M. R.: Robotic grasping and fine manipulation, Vol. 6., Springer Science & Business Media, 2012.
Eizicovits D., Berman S.: Efficient sensory-grounded grasp pose quality mapping for gripper design and online grasp planning, Robotics and Autonomous Systems, 1208-1219, 2014.
Felis J., Jaworowski H., Cieślik J.: Teoria maszyn i mechanizmów, Analiza
mechanizmów, Część 1. Analiza Mechanizmów, Wyd. KMRiDM AGH, Kraków, 2001.
2015, Vol. 39, No 1, 15 - 20
Modification of Joints in Polymer Timing Belts
Grzegorz Domek1), Andrzej Kołodziej2)
1)
Kazimierz Wielki University in Bydgoszcz, e-mail: gdomek@ukw.edu.pl,
2) Higher Vocational State School in Kalisz, e-mail: a.kolodziej@ip.pwsz.kalisz.pl
1. Abstract
Teeth deformation measurements in the connection area indicate that each method of welded joint improvement, decreases deformation and thus improves power transfer capacity of joined belts. In the selected study it means deformation of the connection zone. The difficulties with preparation of strenghtening element significantly reduced selection of solutions. The best results were obtained within belts with connected cord ends and in solutions with restricted load-carrying layer. Depending on the structural solution applied in the cord ends connection, the force transfer capacity is from several to several dozen percent higher. As indicated by the proposed equations, the engagement conditions between belt and pulley can be improved by using pulleys with maximum possible number of teeth, in standard version or even with increased lateral gap.
Keywords:
polymer timing belts, welding process quality, transmission gears, joining area1. Introduction
Replacement of a timing belt causes lots of trouble for their users. It requires disassembly of the entire machine or introduction of the belt in form of a band followed by its joining once it is mounted on the pulleys [Domek 2012]. Welded joining of a belt in a machine requires use of special equipment or sometimes can even be impossible.
A joint significantly reduces belt capacity to transfer torque. It is reduced up to 50% in the solutions used so far, depending on the pressure welding process quality [Domek 2011c, Domek 2013b]. Structural needs are so high that designers return to solutions of joints that have been abandoned for a long time.
2. Joints of timing belts
Like other joints in mechanical engineering, belt joints can be divided into permanent (Fig.1) and disconnected ones, however number of solutions is much smaller here. There are two types of permanent joints: pressure welded and glued. Type of the joint is partially determined by material the belt is made of. Disconnected joints can be divided into screwed joints, pin joints and clamp joints (Fig.2). For all types of belt joints designers seek design modifications enabling increase of the power transmission capacity and shorter installation time. All joint types can be found in belts made of thermoplastic materials. If the polymer belongs to hardening plastics, then it is only possible to make glued or disconnected joint.
In timing belt gears the force is transmitted from the pulley through teeth to load-carrying layer [Dressing, Holzweissig, 2010]. The quality of the load-carrying layer determines mechanical properties of the belt. The neutral axis of cord coincides with the bending axis where belt and pulley pitches are measured. Appropriate connection should cause the lowest possible reduction of the tensile strength of the load-carrying layer as well as maintenance of the belt pitch at the joint area [Domek, 20011c].
Fig. 2 Clamp joints of the ATN system (source Mulco Gruppe)
In case of screwed joints the problem appears in the proper preparation of the belt ends to be joined and clamping them with screws so as to make the tooth rigid. In clamp joints the cord ends are clamped using special connector to prevent
them from displacement in relationship to each other [Domek 2011a, Domek 20011b]. The load-carrying layer is clamped inside teeth or after partial removal of teeth. Recently observed return to pin joints results solely from the fact that it is very easy to prepare such joints (Fig.3). A simple fitter’s workstation is sufficient to do that. However the joint is characterized by many disadvantages.
Fig. 3 Timing belt joint: 1- at the cord height, 2- pin joint inside the belt tooth, h- the distance of the pin in the tooth from the neutral axis of the load-carrying layer Insertion of pins inside a tooth shortens the belt pitch at the pulley arc of contact. This depends on the distance of the pin from the neutral axis of the load-carrying layer as well as the number of teeth at the pulley contact arc (1).
(1)
Such connections can transmit small peripheral forces only. Their pretension force should also be significantly lower than the nominal one. In order to reduce the belt pitch shortening effect and the peripheral force increase effect, the pin joints are provided with hinges located at the load-carrying layer [Bodnicki et al. 2011, Domek 2013a].
Fig.4 Pin for welded joining.
Depending on the type of cord, different hinges are applied: metal one for steel cord and plastic one for glass fiber, polyester and carbon cord (Fig.4). The most common way of joining belt ends is welding (Fig.5), where belt manufacturers use different types of belt end preparation. There are straight and
1
2 h
A joint significantly reduces belt capacity to transfer torque. It is reduced up to 50% in the solutions used so far, depending on the pressure welding process quality [Domek 2011c, Domek 2013b]. Structural needs are so high that designers return to solutions of joints that have been abandoned for a long time.
2. Joints of timing belts
Like other joints in mechanical engineering, belt joints can be divided into permanent (Fig.1) and disconnected ones, however number of solutions is much smaller here. There are two types of permanent joints: pressure welded and glued. Type of the joint is partially determined by material the belt is made of. Disconnected joints can be divided into screwed joints, pin joints and clamp joints (Fig.2). For all types of belt joints designers seek design modifications enabling increase of the power transmission capacity and shorter installation time. All joint types can be found in belts made of thermoplastic materials. If the polymer belongs to hardening plastics, then it is only possible to make glued or disconnected joint.
In timing belt gears the force is transmitted from the pulley through teeth to load-carrying layer [Dressing, Holzweissig, 2010]. The quality of the load-carrying layer determines mechanical properties of the belt. The neutral axis of cord coincides with the bending axis where belt and pulley pitches are measured. Appropriate connection should cause the lowest possible reduction of the tensile strength of the load-carrying layer as well as maintenance of the belt pitch at the joint area [Domek, 20011c].
Fig. 2 Clamp joints of the ATN system (source Mulco Gruppe)
In case of screwed joints the problem appears in the proper preparation of the belt ends to be joined and clamping them with screws so as to make the tooth rigid. In clamp joints the cord ends are clamped using special connector to prevent
them from displacement in relationship to each other [Domek 2011a, Domek 20011b]. The load-carrying layer is clamped inside teeth or after partial removal of teeth. Recently observed return to pin joints results solely from the fact that it is very easy to prepare such joints (Fig.3). A simple fitter’s workstation is sufficient to do that. However the joint is characterized by many disadvantages.
Fig. 3 Timing belt joint: 1- at the cord height, 2- pin joint inside the belt tooth, h- the distance of the pin in the tooth from the neutral axis of the load-carrying layer Insertion of pins inside a tooth shortens the belt pitch at the pulley arc of contact. This depends on the distance of the pin from the neutral axis of the load-carrying layer as well as the number of teeth at the pulley contact arc (1).
(1)
Such connections can transmit small peripheral forces only. Their pretension force should also be significantly lower than the nominal one. In order to reduce the belt pitch shortening effect and the peripheral force increase effect, the pin joints are provided with hinges located at the load-carrying layer [Bodnicki et al. 2011, Domek 2013a].
Fig.4 Pin for welded joining.
Depending on the type of cord, different hinges are applied: metal one for steel cord and plastic one for glass fiber, polyester and carbon cord (Fig.4). The most common way of joining belt ends is welding (Fig.5), where belt manufacturers use different types of belt end preparation. There are straight and
1
2 h
offset finger ends as well as straight and skew triangular ends. Most of these solutions are known from other connections of drive and transport belts.
Fig. 5 Welding process.
In case of timing belts, those operations are aimed at limiting teeth deformation in the area of the connection. The peripheral force and the pre-tensioning force increase the deformation in the belt connection area in comparison to the remaining part of the belt. The connection between ends of the load-carrying layers consists of polymer only, while displacement of the load-carrying layer resulting from the rheological processes causes tooth deformation.
Depending on the number of teeth engaged with the pulley, the engagement process in the connection area becomes difficult. In case of "tangential" transmission gears, where only one tooth of the pulley is engaged with the belt, the measure of the deformed pitch Pl, cannot exceed the pitch in the transmission gear increased by the lateral gap on the pulley. Once that value is exceeded, the belt does not fit in the tooth space any more and thus the belt teeth start to jump over pulley teeth. If there is higher number of teeth at the arc of contact, even for relatively small value of pitch, deformation causes problems with the belt engagement with the pulley. The sum of deformed pitches cannot exceed the sum of pitches at the arc of contact of the pulley - and two-fold lateral gaps -Ls. Once that value is exceeded , the teeth of the belt and the pulley start to interfere, which causes belt breaking (Fig.6).
Fig. 6 Breaking test of a mesh-reinforced belt, Pl- deformed pitch, ΣPl- sum
of deformed pitches in the connection area
(2)
Deformation of the whole joining area has an influence on the coupling process especially with big amount of teeth taking part in meshing. The deformation of a single tooth is important in case of "short" connections. In order to prevent displacement of the load-carrying layer, one uses different methods of cord strengthening and connection. Solutions aimed at teeth stiffening in the area of the joint are additionally used.
offset finger ends as well as straight and skew triangular ends. Most of these solutions are known from other connections of drive and transport belts.
Fig. 5 Welding process.
In case of timing belts, those operations are aimed at limiting teeth deformation in the area of the connection. The peripheral force and the pre-tensioning force increase the deformation in the belt connection area in comparison to the remaining part of the belt. The connection between ends of the load-carrying layers consists of polymer only, while displacement of the load-carrying layer resulting from the rheological processes causes tooth deformation.
Depending on the number of teeth engaged with the pulley, the engagement process in the connection area becomes difficult. In case of "tangential" transmission gears, where only one tooth of the pulley is engaged with the belt, the measure of the deformed pitch Pl, cannot exceed the pitch in the transmission gear increased by the lateral gap on the pulley. Once that value is exceeded, the belt does not fit in the tooth space any more and thus the belt teeth start to jump over pulley teeth. If there is higher number of teeth at the arc of contact, even for relatively small value of pitch, deformation causes problems with the belt engagement with the pulley. The sum of deformed pitches cannot exceed the sum of pitches at the arc of contact of the pulley - and two-fold lateral gaps -Ls. Once that value is exceeded , the teeth of the belt and the pulley start to interfere, which causes belt breaking (Fig.6).
Fig. 6 Breaking test of a mesh-reinforced belt, Pl- deformed pitch, ΣPl- sum
of deformed pitches in the connection area
(2)
Deformation of the whole joining area has an influence on the coupling process especially with big amount of teeth taking part in meshing. The deformation of a single tooth is important in case of "short" connections. In order to prevent displacement of the load-carrying layer, one uses different methods of cord strengthening and connection. Solutions aimed at teeth stiffening in the area of the joint are additionally used.
References
Bodnicki M., Pochanke A., Szykiedans K., Czerwiec W.: Experimental and Simulation Test of Dynamic Properties of Stepping Motors, Proc. 9th International Conference
MECHATRONICS 2011, Recent Technological and Scientific Advances, Springer Verlag, 2011, pp. 25-34
Domek G., Motion analysis of timing belt used in control systems, American Journal of Mechanical Engineering, vol 1, No.7 2013.
Domek G., Dudziak M., Kołodziej A., Timing belt gear design for mechatronics system, Procedia Engineering 96, 2014, 39-43.
Domek G., Trends in development of timing belts for new application areas, Journal of Mechanical and Transport Engineering, Wyd. Politechniki Poznańskiej, Vol 1. 2014. Domek G., Meshing model in gear with timing belt, Journal of Advanced Materials Research, Vols. 189-193, 2011a, pp 4356-4360.
Domek G., Meshing in gear with timing belts, International Journal of Engineering and Technology (IJET), vol. 3, no. 1, pp. 26-29, 2011b.
Domek G., Research on the Contact Area between the Timing Belt and the Timing Pulley, World Congress on Engineering ,WCE 2011c, Lectures Notes in Engineering and Computer Science, Vol. III, s.2242-2244.
Domek G., Timing belts dynamics model approach, Journal of Mechanics Engineering and Automation, 2012, Vol.2 N.8, p 495-497.
Domek G., Timing belts in glass processing systems, International Journal of Emerging Trends in Engineering and Development, Issue 3, Vol.4, 2013b, p.108-111.
Dressing H., Holzweissig F., Dynamics of Machinery, Theory and Applications, Springer Verlag, Berlin Heidelberg 2010.
2015, Vol. 39, No 1, 21 - 36
Using ANSYS and SORCER
Modeling Framework
for the Optimization of the Design of a Flapping
Wing Bionic Object
Marcin Abramowicz1), Konrad Kamieniecki1), Adam Piechna2), Paweł Rubach3), Janusz Piechna1)
1)
Department of Aerodynamics, Warsaw University of Technology, e-mail:marcin.abramowicz@gmail.com, konradkamieniecki@gmail.com,
2)
Institute of Automatic Control and Robotics, Warsaw University of Technology, e-mail: adam.piechna@gmail.com,
3)
Sorcersoft.com, Warsaw School of Economics, e-mail: pawel.rubach@sorcersoft.com
Abstract
Growing modeling software capabilities together with available computational resources enable the modeling of more and more complex multi-physical problems. At the same time, the preparation of such simulation requires a collaboration of both engineers and software. Multidisciplinary Design Optimization (MDO) platforms are used to integrate simulation tools and expert knowledge that represents various engineering disciplines. The presented study demonstrates an effective use of a specialized CFD program and an MDO platform – the SORCER Modeling Framework (SMF) for the automation and optimization of the design of a flapping wing bionic object. The SMF realizes an optimization loop by using independent blocks prepared using ANSYS Workbench. An unsteady flow generated by the prescribed flapping wing trajectory is simulated. A number of geometrical and physical parameters is defined in the SMF model and then transferred to the slave blocks of the CFD program. An automated ANSYS workflow generates a geometry of computational domain, realizes it's proper meshing, initializes and performs the simulation, and finally passes the results to the SMF. The proposed system is an example of usage of the SMF that demonstrates the connection of specialized knowledge and a complex CFD simulation with simple and efficient control.
Keywords:
MDO, Design Optimization, ANSYS, SORCER, CFD, Flapping Wing, Bionic Object, Dragon Fly, Simulation1.
Introduction
The increasing complexity of modern constructions adds new requirements to the design processes and usually means that more disciplines have to be taken into account during the design. These facts decide that engineers’ specializations become more advanced and hence narrower. Nearly each project needs an intensive collaboration of a group of engineers – specialists that are experts in one of the fields but not necessarily in others. Traditionally, the design decisions were made
