Matters needing attention in the processing of multi-strand springs:
1. Springs without support rings and springs with too thin wire diameters should not be welded to the spring head, but the end cable should not be significantly loose, and should be deburred. For multi-strand springs that need to be welded on the head, the length of the welding part It should be less than 3 times the cable diameter (the longest is no more than 10 mm). The heating length should be less than one circle, and it should be smoothed after welding. The welding part should be locally annealed at low temperature during gas welding.
2. For multi-strand springs with a large H0/D2 value, attention should be paid to their deformation during heat treatment, consider whether to wear the mandrel and pay attention to the placement method, and select the appropriate heat treatment equipment. Under the condition of repair, it can be carried out Repeated tempering and hot pressing to achieve the purpose.
3. The support ring can be selected according to the product requirements, cold and hot, two methods. It is not allowed to heat the spring to sparking or whitening by using the hot coupling method. The temperature of the silico-manganese steel should not be higher than 850°C. The support ring and the effective ring should For effective contact, the gap must not exceed 10% of the nominal gap between the circles.
Fourth, the important spring compression time is 24 hours, ordinary springs are 6 hours or continuous compression 3~5 times, and each time is maintained for 3~5 seconds. The gap between the spring and the mandrel during compression is 10% of the diameter of the mandrel. If the gap is too small, it is difficult to operate, and if the gap is too large, it is easy to cause the spring to bend and deform. If one of the springs is broken during compression, the rest should be processed again.
5. The characteristics of the multi-strand spring can be determined by the adjustment lead, and the cable distance can be adjusted as necessary during winding. The twisting distance can be 3 to 14 times the wire diameter, but generally 8 to 13 times are better. The spring force is also related to the free height, The parallel end ring, outer diameter and wire performance are closely related, and can be changed by adjusting one or several of them.
The surface treatment of the spring is generally phosphating treatment, but other treatments can also be carried out. When the coating is zinc and cadmium, the hydrogen removal treatment should be carried out after electroplating, and 3% (not less than 3 pieces) should be taken after hydrogen removal. The retest should be treated with a set point, and there should be no breaks during the retest. The spring should be cleaned of surface dirt, salt marks, and oxide scale. The method can be sand blowing or gasoline cleaning, but acid cleaning cannot be used.