Heat treatment technology of bar shearing die blade

Abstract

The invention discloses a heat treatment technology of a bar shearing die blade, which comprises the following steps of: 1) quenching: heating a box-type resistance furnace to 550 DEG C, putting the bar shearing die blade into the furnace, and preserving heat at 550 DEG C for 60 minutes; and further increasing the furnace temperature to 840 DEG C, preserving heat for 45 minutes, and discharging the bar shearing die blade from the furnace and performing oil cooling; and 2) annealing: heating a pit-type resistance furnace to 250-350 DEG C, putting the quenched bar shearing die blade into the pit-type resistance furnace, preserving heat at 250-350 DEG C for 120-180 minutes, discharging and performing air cooling. The bar shearing die blade disclosed by the invention does not experience brittle fracture easily, and the cutting edge is not easily disintegrated; one bar shearing die blade can cut 20-30 thousand bars; after long-term use, the shearing die blade is still useful after coping, and the service life is prolonged by over 30 times; and moreover, the utilization rate is high, the needs for production and development are met, and the production cost is greatly saved.

Description

technical field [0001] The invention relates to a heat treatment process, in particular to a heat treatment process capable of prolonging the service life of a shearing die blade, and belongs to the technical field of heat treatment. Background technique [0002] Marine anchor chain is an important part widely used in ship berthing, usually made of anchor chain steel, which is a low-alloy structural steel. Anchor chain steel bars with a diameter below Ф42mm are generally blanked by a punching machine. The material used for the shearing die blade of the punching machine is CrWMn, which belongs to low alloy tool steel and has high hardness, strength and wear resistance. , The blades of the bar shearing die are prone to brittle fracture or edge collapse. A pair of blades can only hold about 1,000 pieces of the bar shearing die, and the service life of the bar shearing die blades is extremely short. The surface hardness requirement of the existing bar shearing die blade is HRC5...

AI Technical Summary

Problems solved by technology

[0003] The chemical composition of the raw materials of the existing bar shearing die blades meets the requirements of relevant standards. No obvious defects are found on the corroded surface of the low-magnification microstructure inspection sample. The microstructure of the raw material is normal. The normal spheroidized annealed structure meets the corresponding hardness requirements. The microstructure at the fracture of the bar shearing die blade is a normal quenching and low temperature tempering structure, which meets the surface hardness requirements of the bar shearing die blade. The fracture surface of the bar shearing die blade It is located on the contact surface between the blade and the bar along the transverse direction of the blade body, and the fracture starts at the top corner of the edge of the blade edge. From the above analysis, it can be concluded that the strength and hardness of the existing bar shearing die blade are too high, and the toughness is poor, and the fracture is after heat treatment. The main reason is that the tempering temperature of the bar shearing die blade is low during heat treatment, and the tempering holding time is short, resulting in insufficient tempering, and residual stress still exists in the bar shearing die blade. In addition, the bar shearing die blade The cutting edge of the die blade is too sharp, which is prone to stress concentration, and becomes the crack initiation position of the die blade for bar shearing

Images