Die parts can be roughly divided into three types according to their different shapes: plate, special-shaped parts and shafts. The common process is roughing - heat treatment (quenching, quenching and tempering) - fine grinding - electric machining - clamping (surface treatment) - combined processing.
Part heat treatment
In the heat treatment process of parts, the internal stress should be controlled while the required hardness is obtained, so as to ensure the dimensional stability of parts. Different materials have different treatment methods
One hardening process can obtain higher strength and wear resistance, and it is better for the die with wear as the main failure form. In production, some workpieces with more corners and complicated shapes are encountered. Tempering is not enough to eliminate the quenching stress. Stress relief annealing or aging treatment should be carried out before finishing to fully release the stress.
The secondary hardening process, quenching at 1050-1080 C, tempering at 490-520 C for several times, can obtain higher impact toughness and stability, and is suitable for die with chipping edge as the main failure form. The cost of powder alloy steel is high, but its performance is good. It is becoming a widely used trend.
Two. Grinding of parts
There are three main types of machine tools used in grinding process: surface grinder, internal and external grinder and tool grinding tool. When finishing grinding, grinding deformation and grinding cracks should be strictly controlled. Even very small cracks will appear in the subsequent processing and use.
Three. EDM control
Modern mold factory, can not lack of electrical machining, electrical machining can be all kinds of special-shaped, high hardness parts for machining, it is divided into wire cutting and EDM two kinds.
Four. Surface treatment and distribution
The knife marks and wear marks on the surface of the parts are the places where the stress is concentrated and the source of crack propagation. Therefore, after finishing the machining, it is necessary to strengthen the surface of the parts and grind them by clamping to deal with the hidden troubles. Some edges, sharp corners and orifices of the workpiece are blunt and R. Generally speaking, the surface of electro-machining will produce about 6-10 micron hardened layer, gray-white color, brittle hardened layer with residual stress, before use to fully eliminate the hardened layer, the method is to polish the surface, grinding to remove the hardened layer.
Practice has proved that good finish machining process control can effectively reduce parts out of tolerance, scrap, and effectively improve the mold success rate and service life.