Design And Study On Automatic Assembly Machine And Its Control System For Product With Circlip And Pin

Rapid changes in today’s market demands, the development of individuation and diversification of product poses severe challenge to today’s manufacturing industry. After decades of development, most sectors of production have overcome lots of obstacles and have achieved great development. However, assembly sector, which is the last sector of production, can not catch up with the development of other sectors. The high level of automatic in present machining has been realized. Therefore the productivity of parts increased in a large scale. However, because of the complexity of assembly sector, the automation of assembly was always hard to realize. Afterward, the lack of automation in assembly sector becomes a bottleneck in entire manufacturing, which seriously limits the productivity of product.(1) AT the background of high demands of automation and flexibility, this paper designed an automatic assembly machine based on the user requirement. The machine is reconstructed based on the prototype of automatic teaching system from FESTO company in Germany.(2) First, this paper analyzed the requirement of assembly process. And made global configuration and controlling scheme.(3) Then, this paper introduced using CAD software UG/NX7.5to design the mechanical part of this machine. It designed every single part of the machine including feeding system and assembling mechanism.(4) During the design. FEM software ANSYS/LS-DYNA was applied to simulate the procedure of pressing the circlip onto the pin. The punch force from the result of simulation was then used to be reference of choosing the punch piston.(5) Then the electric-pneumatic system of the machine was designed, including pneumatic circuit and program for control. The program was write by software of TWINCAT, which is from BEKCHOFF company in Germany. This part testified the availability of this automatic assembly system from theoretical side.(6) At the end of this paper, the optional position control to the assembly mechanism was explored, since the potential demands of flexibility of production in future was necessarily considered. Pneumatic servo system was introduced to establish the model of control system. At first, the mathematic model of the servo control system was constructed based on the physic model of using proportional valve to control a rodless piston. Then the open-loop transfer function was given from a series derivation. The dynamic characteristic was then analyzed based on the transfer function. At last, a real model of using proportional valve MPYE-5M from FESTO to control lodless piston DGP-12was established. Meanwhile the stability of the real system is analyzed with MATLAB.(7) Comparison was made that the characteristic of step response from PID control and from fuzzy control. The result showed that different control methods more or less improved the behavior of the system, despite that there was a steady state error in P control and a slight overshoot in PID control. The result of fuzzy control was most satisfied in this case. The model which using proportional valve to control piston could also be a nice reference to real system or other similar cases.