Precautions in spring factory processing
1. The spring without bearing ring and the spring with too small wire diameter shall not be welded with the spring head, but the steel cable at the end shall not be obviously loose and shall be deburred. For multi strand springs with welded heads, the length of the welded part shall be less than 3 times the cable diameter (Z length shall not be more than 10mm). The heating length shall be less than one circle. After welding, it shall be polished and smooth. During gas welding, the welding part shall be subject to local low-temperature annealing.
2. According to the product requirements, the bearing ring can be cold combined and hot combined. It is not allowed to heat the spring to spark or whiten by thermal bonding. The temperature of silicon manganese steel shall not be higher than 850 ℃. The bearing ring and the effective ring shall be in effective contact, and the clearance shall not exceed 10% of the nominal clearance between the rings.
3. The characteristics of the multi strand spring can be determined by the adjustment lead, and the cable distance can be adjusted when winding. The screwing distance can be 3 ~ 14 times of the steel wire diameter, but generally 8 ~ 13 times is preferred. The spring force is also closely related to the free height, parallel end ring, outer diameter and steel wire performance, and can be changed by adjusting one or more of them.
4. The pressing time of important springs is 24 hours, that of ordinary springs is 6 hours or 3-5 times of continuous compression, each time for 3-5 seconds. The clearance between the spring and the mandrel should be 10% of the diameter of the mandrel during compression. If the clearance is too small, it is difficult to operate. If the clearance is too large, it is easy to cause bending deformation of the spring. If one of the springs is broken during compression, the rest shall be reprocessed.
5. For multi strand springs with large H0 / D2 value, attention shall be paid to their deformation during heat treatment, whether to wear the mandrel and pay attention to the placement mode, and select appropriate heat treatment equipment. Under the condition that repair can be carried out, multiple tempering and hot pressing can be carried out to achieve the purpose.
6. The surface treatment of the spring is generally phosphating treatment, and other treatments can also be carried out. Where zinc and cadmium are to be coated, hydrogen removal treatment shall be carried out after plating. After hydrogen removal, 3% (not less than 3 pieces) shall be taken for retest and standing treatment. There shall be no fracture during retest. The surface dirt, salt mark and oxide scale of the spring shall be removed by sand blowing or gasoline cleaning, but acid washing is not allowed.