| The main content of this paper is the development of automatic feeding spot welding equipment used for manual hydraulic pump,to solve the problem which nowadays exists in traditional resistance spot welding process,such as low-level automation,low productivity,low accuracy of welding position and poor quality of solder joints.According to some relevant technical indices,the equipment is divided into three subsystems:automatic feeding system,manipulator system and spot welding system.Feasible design plans for subsystems are put forward based on the theoretical knowledge of machine science.And according to the design scheme,the structural design of subsystems is completed by using three-dimensional digital software.Finally,make reasonable spatial layout for subsystems to form a unified whole.ADAMS software is applied to the kinematics simulation analysis of the manipulator structure to to ensure that the structure meets the requirements of the kinematic design.ANSYS software is used to analyze the static analysis of the spot welding structure to ensure that the structural design of the key parts meets the requirements of strength and stiffness.Then the modal analysis of the whole machine is carried out to ensure that the resonance phenomenon will not appear.So as to provide reliable technical support for the realization of the overall design plan.Pneumatic driving technology is adopted after considering the characteristics and production cost of the automatic spot welding equipment.Then the pneumatic schematic diagram is designed and the pneumatic components are selected.According to the structure features and functional requirements of the equipment,the overall scheme of the electrical control system is designed.The master and subordinate control mode of the upper and lower computer is adopted,of which the lower computer is centered on the PLC,and the upper computer is centered on the HMI man-machine interface.The allocation of PLC port is completed,and the peripheral wiring scheme of PLC is clearly defined.The PLC program is programmed by calling the subroutine in the main program with ladder diagram language.By establishing connection between database variables and CPU variables,the communication between man machine interface control element and PLC is realized.It meets the needs of human-machine interaction and intelligent production requirements.The optimum spot welding parameters of Unequal thickness 304 stainless steel and 45steel are determined by the experiment of the single side double spot welding.The welding current is 8.5kA,the welding time is 0.16s,and the electrode pressure is 0.3MPa.The shear load of the joint obtained from the spot welding parameters is 3160N,which reaches the technical specifications.Through the production test,it is proved that the position precision of M type press is in the range of 35°±0.5°.On this foundation,the equipment capability index Cmkk is determined to be higher than that of the value 1.67 of the enterprise.At last,the production efficiency of the automatic feeding spot welding equipment has been improved by 1 times at least. |
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