Novel gripper module and method for automated assembly of miniature parts

Abstract

During assembly process, the miniature part needs to be fixed in its assembly position. In some occasions where adhesive is used, the joining force is not established due to the adhesive curing process, in that case the locking of parts is required. Manual locking is difficult to meet the increasing demand for mass production. To solve this problem and realize fully automatic assembly, a novel gripper module was designed and corresponding locking method was proposed. Thanks to the functional integration, the gripper module is capable of manipulating and locking the part. This module is integrated into the assembly system and plays a crucial role in automatic assembly. The locking method for automatic assembly is based on the integration of the part picking up and the locking unit releasing. After being placed accurately at its desired position, the miniature part can be automatically locked by releasing the locking unit. The innovative structure and mechanism of the gripper module convert the spring force into the locking force of the miniature part, ensuring non-rigid locking and suitable small locking force. Locking principle, flexibility and limitations of the proposed method were clarified in detail. Moreover, an effective compensation strategy was used to achieve accurate and stable pickup of the part, which increased the reliability of the assembly process. During automatic locking, the disturbances to the part due to the eccentric load were analyzed. The effectiveness of the gripper module and proposed method was verified by experiment. Experimental results indicated that the modular system integrated with the gripper module could meet the requirements of fully automatic assembly. Manual locking is replaced by automatic locking, and workers are liberated from tedious manual operations. The improvement of automation level enables assembly equipment to be applied to mass production scenarios.

Keywords

Fully automatic assembly / Miniature parts / Automatic locking / Gripper module

References

[1] Hu SJ, Ko J, Weyand L, et al. Assembly system design and operations for product variety. CIRP Ann Manuf Technol, 2011, 60(2): 715-733.

[2] Lu QB, Wang YN, Wang XX, et al. Review of micromachined optical accelerometers: from mg to sub-μg. Opto-Electronic Adv, 2021, 4(3): 33-56.

[3] Bortolini M, Faccio M, Galizia FG, et al. Design, engineering and testing of an innovative adaptive automation assembly system. Assem Autom, 2020, 40(3): 531-540.

[4] Wang XD, Chen Y, Luo Y et al (2011) Adjustment of vision system parameters and image processing algorithms for measurement of miniature parts in automatic assembly. Proceedings-IEEE 2011 10th international conference on electronic measurement and instruments, 16‒18 August 2011, Chengdu, China

[5] Wang XD, Zhang LF, Xin MZ et al (2015) The precision measurement and assembly for miniature parts based on double machine vision systems. Proceedings of SPIE-the international society for optical engineering, 8‒10 August 2014, Changsha, China

[6] Rosati G, Faccio M, Carli A, et al. Fully flexible assembly systems (F-FAS): a new concept in flexible automation. Assem Autom, 2013, 33(1): 8-21.

[7] Weck M, Peschke C. Equipment technology for flexible and automated micro-assembly. Microsyst Technol, 2004, 10(3): 241-246.

[8] Clévy C, Hubert A, Chaillet N. Flexible micro-assembly system equiped with an automated tool changer. J Micro-Nano Mechatron, 2008, 4(1/2): 59-72.

[9] Burisch A, Loechte C, Raatz A et al (2008) Cambio-a miniaturized tool changer for desktop factory application. Proceedings of EUCOMES 2008-the 2nd european conference on mechanism science, 17‒20 September 2008, Cassino, Italy

[10] Wang XD, Chi YZ, Luo Y (2014) An exchangeable gripper module integrated in the assembly system for multi miniature parts. 2014 IEEE international conference on information and automation, 28‒30 July 2014, Hailar, China

[11] Wang XD, Wang L, Zhang XW, et al. Micro-stress assembly of fragile miniature parts. Key Eng Mater, 2011, 483: 668-673.

[12] Wang XD, Song HX, Liu C, et al. Automatic measurement and assembly of miniature parts based on machine vision. Harbin Eng Univ, 2011, 32(9): 1117-1122.

[13] Ruan Y, Ren TQ, Wang XD, et al. Automatic precision assembly system for trans-scale miniature parts. Opt Precis Eng, 2015, 23: 259-265.

[14] Zhang XW, Wang XD, Luo Y, et al. A precise automatic assembly system for fabrication of complex miniature products. Adv Mater Res, 2011, 317-319: 757-763.

[15] Zhang XW, Wang XD, Luo Y, et al. Measurement and assembly of trans-scale miniature parts. Nanotechnol Precis Eng, 2012, 10(4): 342-347.

[16] Ferreira P, Anandan PD, Pereira I. Integrated design environment for reusable modular assembly systems. Assem Autom, 2019, 39(4): 664-672.

[17] Gendreau D, Gauthier M, Heriban D, et al. Modular architecture of the microfactories for automatic micro-assembly. Robot Comput-Integr Manuf, 2010, 26(4): 354-360.

[18] Naskali AT, Kunt ED, Sabanovic A. Bi-level modularity concept within a robotic assembly module of a microfactory setting. Int J Adv Manuf Technol, 2013, 66(9/12): 1255-1269.

[19] Zhakypov Z, Uzunovic T, Nergiz AO, et al. Modular and reconfigurable desktop microfactory for high precision manufacturing. Int J Adv Manuf Technol, 2016, 90(9/12): 3749-3759.

[20] Shao C, Zhang ZJ, Ye X, et al. Modular design and optimization for intelligent assembly system. Procedia CIRP, 2018, 76: 67-72.

[21] Åkerman M, Fast-Berglund Å, Halvordsson E, et al. Modularized assembly system: a digital innovation hub for the Swedish smart industry. Manuf Lett, 2018, 15: 143-146.

Funding

LiaoNing Revitalization Talent Program(Grant No. 2002020)

Major Project of Basic Scientific Research of Chinese Ministry(Grant No. JCYK2016 205A003)