| 摘要 |
PURPOSE:To prevent generation of sag at the edge of a cam part and the consequent deformation of the shape thereof by using a specifically constructed plasma torch in the stage of subjecting the surface in the cam part of a cam shaft to a hardening treatment by remelting using the plasma torch. CONSTITUTION:The surface 22 in the cam part of the cam shaft is remelted by the plasma arc of the plasma torch 10 and the surface is quickly chilled to harden. The torch 10 which has a nozzle chip 12 provided with a plasma ejecting port 17 at the center and auxiliary ejecting ports 18, 18 opened diagonally on both sides thereof and has a supply pipe for metallic powder is used in this case. A DC voltage is impressed between the cam part 22 and the tungsten electrode 16 of the torch 10 then a shielding gas and working gas such as Ar are passed. The plasma arc by the working gas is injected by the electric discharge between the electrodes. The edge part on the cam surface is melted by the plasma arc 23 from the port 18 and the molten part at the edge is shallower than the molten part by the port 17, by which the consequent deformation of the shape by the sag is prevented. |
