Induction quenching equipment manufacturer analyzes quenching deformation defects and process improvements of disc scissors of sock knitting machines

Sock knitting machine disc scissors, you can tell at a glance that it is a type of scissors. Maybe many people don’t know much about it. However, if you can imagine the scissors used in our homes and their usage, you can know that the sock knitting machine disc scissors are How are the disc scissors working? Our household scissors need to be quenched and heat treated to improve their hardness, wear resistance and service life, as do the sock loom disc scissors. Today, we will briefly analyze the quenching deformation defects and process improvements of the disc scissors of the sock knitting machine.

The disc scissors of the sock knitting machine are made of CrMn steel. Disc scissors are thin-walled parts with a wall thickness of approximately 1-1.5nm and a relatively complex shape. The heat treatment process of disc scissors is heating at 850-860℃, then quenching, and tempering at 180-200℃. The technical requirements are: the hardness of the workpiece after heat treatment is 58-62HRC, the flatness is ≤0.05mm, and the roundness is ≤0.1mm. Previously, workpieces were tied with wires and then hung for quenching. Due to the thin wall and complex structure of the workpieces, out-of-tolerance flatness and roundness often occurred, and correction was difficult, resulting in many workpieces failing and being scrapped.

In order to reduce the quenching stress and deformation of the workpiece, a preheating treatment is added to the CrMn steel disc scissors. The preheating temperature is 300-700°C. The workpiece is then placed in a quenching fixture for quenching and heating. The outer diameter of the mandrel in the fixture is slightly smaller than the inner diameter of the workpiece. Small. In order to prevent the mandrel and the workpiece from getting stuck during quenching, the mandrel is made of steel without martensitic transformation. In order to ensure that the workpieces are well quenched and cooled, a lining ring is placed between every two workpieces to separate the two workpieces, so that each workpiece can be cooled more fully. The workpiece is quenched and heated to 850-860°C, and is oil-cooled after heat preservation.

The tempering fixture is designed and manufactured for tempering treatment. The correction ring placed between the workpieces has two functions. One is to correct the roundness of the disc scissors, and the other is to have a flattening and bending effect on the workpiece plane, so that the curvature of the workpiece surface is equal to the The roundness is greatly reduced. When operating, pay attention to the fact that when the workpiece still has residual heat after quenching (about 100-150°C), press the workpiece into the correction ring. The correction ring separates the workpiece. The mandrel is inserted into the middle of the workpiece and tightened with pressure plate bolts, which actually plays a role in shaping. The tempering temperature is 180-200°C. The workpiece has good performance after heat treatment, the hardness is 58-60HRC, the deformation is small, the flatness error is <0.03mm, and the roundness error is <0.05mm, all of which meet and exceed the technical requirements.

Okay, this article briefly analyzes the quenching deformation defects of the disc scissors of the sock knitting machine and its improvement process. I hope you can apply what you learned today to your work and produce high-quality disc scissors of the sock knitting machine. . Of course, if you have a better method, you can share it with all of us.