Structure Design Of Placement Machine And Research On Bottom Layer Control System

With the rapid development of electronics and information technology industries, electronic manufacturing is facing the challenge of microminiaturization and high integration. SMT is well adapted to these changes, which is a part of electronics advanced manufacturing technology. Placement machine is the key part of SMT, and it affects the entire assembly production capacity and efficiency, which is a precision manufacturing equipment, involving mechanical, electronics, automation and computer science.This thesis takes the chance of the enterprise demand, in order to develop an automatic placement machine with low price, high precision and high cost-effective performance.Firstly, after fully understanding the structure, working principle of the placement machine and our project requirements, we analyze the basic structure that we maybe choose and study the X-Y cantilever mechanism, and we also compare the advantages and disadvantages from different transmission mode. According to the X-Y transmission system, which highly affects the SMD precision, we discuss how to choose the proper type of ball screw and motor, and calculate their parameters in detail, and we get cost-effective products based on these analysis. At the same time, we study the impact on guide life caused by the system acceleration and deceleration motion.Based on the whole functions of control system, we divided the entire hardware system into several parts, and then analyze each of sub-module. We choose servo control system for X-Y mechanism, and improve the accuracy further using the design of full closed-loop control mode with the help of grating displacement sensor based on servo control. We also do the research on Z/T-axis and PLC module which make the mounted head mount chip accurately, and achieve their basic functions. We realize the software control between the master PC and the slave computer using RS-232 serial communication relying on hardware system. After that, we write the control system software based on PC platform, which are used to operate servo system and PLC system, and debug them.The results based on placement machine function test show that the design of placement machine in this thesis meet the system function requirements, and the repeatability positioning accuracy of mount head is less than 0.02mm. Besides, the bottom layer software can make the basic control functions, and it has strong expansibility and easy for upper layer. At the end of this thesis, we summarized our main work, and then put forward some improvement measures such as high precision, high speed and visual inspection.