Analysis on the heat treatment process of needle cylinder by high-frequency heating equipment

The needle cylinder is one of the main components on the circular loom. It is mainly used to arrange the position of the card clothing and the trajectory of the reciprocating motion, such as the needle cylinder of the weft knitting machine. During the working process, the needle cylinder will rub against the fabric. Therefore, for the needle cylinder, it must have high hardness, good wear resistance and toughness. Then the raw material for the production of syringes needs to choose 45 steel with better performance, and use high-frequency heating equipment for quenching heat treatment process, so that the finished syringes can meet its working requirements.

According to the technical characteristics and working conditions of the needle cylinder, the production process of the needle cylinder includes forging and forming of raw material 45 steel, annealing treatment (preparatory heat treatment), finishing, quenching heat treatment, inspection, etc. Technically, the surface hardness of the heat-treated syringe is required to reach about 53HRC, and the hardened layer is 4mm. The quenching part is at the groove on the inner side. The temperature must reach 860°C during heating. Tempering treatment is carried out at a temperature of about 100%. In the process of heat treatment, since the needle barrel is made of 45 steel, after forging, the surface hardness is very high, the internal stress is relatively large, and there are coarser grains, so high-frequency heating equipment must be used first. It undergoes annealing heat treatment, which can improve the cutting performance of the needle cylinder and pave the way for the subsequent finishing and heat treatment.

In the process of heat treatment, local quenching treatment should be carried out on the inner groove of the needle cylinder, which not only ensures that the depth and hardness of the hardened layer meet the qualified requirements, improves its wear resistance, but also reduces the degree of deformation of the needle cylinder, preventing Partial cracking occurs. The reason for annealing before finishing is to increase the hardness of the forging, eliminate processing stress, and make its structure uniform.

In the heat treatment process of high-frequency heating equipment to the syringe, the heating process parameters must be strictly controlled, and the pressure of the cooling water should be checked at any time to avoid excessive heating temperature, long time, or excessive cooling speed, resulting in overheating , is the needle cylinder cracking. Before heating, adjust the distance between the induction coil of the high-frequency heating equipment and the needle cylinder to ensure that the needle cylinder is in the middle position. If the distance is equal, the hardness of the surface heat treatment of the needle cylinder will be uniform and the production efficiency will be improved.