Research On Rivet Cutting Device Based On Short Arc Machining

Rivet connection technology,characterized by reliable connection,light weight,low cost and simple processing technology,has become the first choice of mechanical connection schemes in the world,and has been widely used in production and manufacturing.In the process of equipment maintenance or production-manufacturing,the rivets which do not meet the riveting quality and technical requirements,are functional failed and severely worn ones shall be removed and re-riveted.On most occasions,electric drill and gas cutting are still used to cut rivets,which is low efficiency,costly and easy to cause workpiece damage.On the basis of the combination of EDM rivet cutting equipment,this thesis puts forward a rivet cutting scheme which is based on short arc machining.It uses high-energy arc discharge in short arc machining to directly cut the rivet head or collar,and then punch out the rivet rod with a punch to take out the rivet.Based on the analysis of EDM and short arc processing technology at home and abroad,the mechanism of mechanical motion arc breaking and the mechanism of working fluid dynamic arc breaking are studied.According to the actual needs of rivet cutting,a new arc breaking mode is selected by combining the two mechanisms.On this basis,the mechanical structure and electrical control system of the short arc rivet cutting device are designed.The structure design and analysis of the feed adjusting mechanism,the rotating mechanism and the flushing device of the tool electrode are carried out.The hardware design of the chopping circuit of the pulse power supply,the computer control system and the processing gap voltage detection system of the short arc rivet cutting device is completed.PIC16F887 single chip microcomputer is used as the controller to complete the software design of machining pulse control,electrode feed control,rotation control and gap voltage detection,so as to ensure that the machining pulse can be adjusted while the rivet is being removed,and the damage to a device due to a short circuit caused by the feed speed of tool electrode is greater than the removal speed of the rivet in the process of machining will not appear.Finally,the equipment debugging and tests of the short arc rivet cutting device are carried out in the laboratory,and the rivet cutting tests are completed.Using LabVIEW programming platform,the data acquisition program of machining arc is compiled to record machining data.Through the analysis of machining data,the feasibility of the design scheme and the effectiveness of arc breaking control method are confirmed.The relevant processing parameters of cutting rivet by short arc are basically determined,which lays a foundation for further development of rivet cutting equipment.