The camshaft edge trimming die is a die for cutting the flash of the forging blank. The material is 5CrMnMo steel, the outer size is larger, and the shape of the inner cavity is complex. Because it works at a higher temperature, the cutting edge is required to have higher hardness, wear resistance and heat resistance. Most of the die in use is caused by edge strain, cracking, and corner collapse. If a new set of molds is re-manufactured, it will not only be costly, but also require external processing and a long production cycle. Therefore, the surfacing method is used to repair the scrapped mold.
1) According to the damage of the mold, the damaged part is milled first to remove the crack. And milled around the cavity 7mm wide and 6mm deep. The roots are connected with R5 fillets. Insulate the workpiece furnace at 450 degrees for 2 hours. After the furnace is released, the cavity is placed horizontally upwards. Insulation measures are taken above and below and around.
2) The special high-entropy alloy spray welding powder surfacing of Hunan WISE New Material Technology Co., Ltd.. is adopted, and the plasma powder surfacing welding process is adopted.
3) Symmetrically oriented connection method is used during surfacing welding. Each surfacing is about 100mm long and 2-3mm thick. It fills the arc pit during rice collection. After welding, lightly tap the weld bead with a hammer. The surfacing layer should have a processing allowance of 2-3mm. Defects found after welding should be removed and repaired in time. The temperature between layers is controlled above 300 degrees.
4) Immediately send the mold to the furnace, heat it to 450 degrees, keep it warm for 3 hours, and then cool it to about 20 degrees with the furnace and air cooling. After cooling to room temperature, a hard alloy milling cutter is used for machining.
The hardness of the die substrate after surfacing is 53HRC, and the hardness of the edge surfacing layer is 53 ~ 54HRC. Due to the appropriate process method, the deformation is very small and meets the design requirements. The production and use prove that the quality of the mold after the repair welding is good. A total of 36,000 forging blanks are cut, which exceeds the service life of the new mold by 5 times and meets the production needs.