Study On Machinery And Technologies Of Pressing For Powder Liners

Affected by the current pressing technology, defects existing in powder liners such as thickness difference, low crushing strength result in low perforation penetration. Meanwhile, due to artificial factors, the production efficiency of powder liners is not high, and the uniformity is bad. So the pressing technology with punch pressing and simultaneously die spinning and centers in this pressing process was discussed. By adding some auxiliary devices such as automatic powder weighing, powder feeding, liner fetching, liner detective and liner placing to an improved four-column hydraulic press, a set of automatic pressing machinery that satisfies the liner dimension and quality requirement was developed.According to industrial reality, some pressing tests were done by modifying the pressing parameters such as pressure applied to the mold, pressing velocity of mold and rotational velocity and rotational time of the die. The results show that increasing pressure (18MPa), slowing down pressing speed of the punch properly and increase spinning time of the die (5s-8s) can improve the pressing intensity of powder liners. When the spinning speed of the die is faster than 450rpm the thickness difference and pressing intensity of powder liners change little. At last, the overall performance of liners was tested. Under the same conditions of liner material and charge, the shooting depth of this newly made liner increases by 10.6%. This paper researches mainly includes the following aspects:(1) The forming process of liner was analyzed, and the design idea of pressing automation is presented. The design on mechanical structures of this automatic liner pressing machinery was finished, and a hydraulic system and a PLC control system are applied to the machinery; then the automatic machinery was contrived successfully.(2) Some pressing tests are done using the above machinery, and the factors that affect liner quality are investigated.(3) The newly made perforators are loaded to do some shooting, and the shooting depths are compared with the results made by using the same size old perforators.The research on the subject has been used in actual production, ensuring the quality of powder liner, and it increased production efficiency. Meanwhile the results of this study can also be applied to other manufacturing powder metallurgy products.