Study On Machining Technology Of Globoidal Cam Employed In Automatic Tool Changer (ATC) Of Machine Center

With the development of machine building industry, the use of machine center ismore and more extensive.The machining of globoidal cam employed in automatic toolchanger (ATC) which is a key function unit of machine center is more difficult. Whenthe automatic tool changer employing domestic globoidal cam is running, the noiseand vibration are all excessive. And most of high order products employed in Chinaare import goods. So the study on machining technology of globoidal cam employedin ATC of machine center is significant.The profile machining error and milling force in milling of the globoidal cam areanalyzed. And machining experiment of the globoidal cam and performance test ofthe automatic tool changer are also done. The contents studied in this paper including:Firstly, the influence, of the A-axis error and the B-axis error of machine tool, onthe profile error of the globidal cam, is studied. The minimum distance method ispresented for mathematic modeling of the profile error of globoidal cam. The linearinfluence coefficient is used to solve the maximum profile error of globoidal cam. Theisoline map is used to describe the relation between the maximum profile error of thegloboidal cam and the errors of the A-axis and the B-axis. The isoline map couldcontribute to the determination of precision of machine tool employed in machininggloboidal cam.Secondly, the influence on the profile error of the globoidal cam, of the locationerror of globoidal cam, resulting from locating twice for milling and grinding, isstudied. The isoline map is used to describe the relation between the maximum profileerror of globoidal cam and the location errors. This could contributes to thedetermination of the fixture precision. The location error of the part can be controlledby controlling the precision of the fixture.Thirdly, the milling force in milling the globoidal indexing cam is studied. Themathematic model of milling force is built. And the process of computing the millingforce is presented. The milling force in milling the TC40type globoidal cam iscomputed. When finish milling is being done, the milling force of right-hand slot ofthe part is smaller than that of the left-hand slot of the part. When rough milling isbeing done, if the milling depth of slots are too larger, this phenomenon would alsoappear. The reason of this phenomenon is analyzed. It is presented that thisphenomenon could be controlled by modifying the milling parameters.Fourthly, the machining experiment of the globoidal cam is done. By consideringthe computed results and analyses of the machine error and the milling force, thesuitable parameters of machining the globoidal cam are presented, and the globoidalcam is made successfully, by modifying the fixture and the processing parameters. The widths of right-hand and left-hand slots are identical. This appears that thequestion resulting from the right-hand and left-hand slots is overcomed.Finally, the performance test and fatigue test of the ATC employing the globoidalcam made in the machining experiment are done. The test results of the displacement,speed, acceleration of the follower of globoidal cam are identical to the desired results.And the comparison between the part made in the machining experiment and thatmade in Japan is done. The comparative result indicates that the performance of thegloboidal cam made in the machining experiment is no less than that of theproductions made in Japan. Then2000000times reliability test of the ATCemploying the globoidal cam made in the machining experiment is done. In theprocess of testing, the vibrating speed of cam housing is inspected. When the principalaxis appears failure, the ATC is normal. After2000000times, the ATC is alsonormal; Then the disassemblying of the ATC is done, and the wear pattern of the partsincluding the globoidal cam is examined. the wear of the globoidal cam is smallerthan those of the other parts. This indicates that, the quality of the globoidal cam,made in the machining experiment, is reliable, and the study is successful.