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Defects Of Hollow Rivets With Low Carbon Steel.
Apr 01, 2018

In recent years, due to the low carbon deep drawing steel has high purity of steel, cold work hardening is small, deep drawing formability, good and strong degree is high, wear resistance, good security features, are widely used in mechanical engineering of production manufacturing and toys and other industries.

The basic process to make hollow rivet is: the plate material, pickling, phosphating, saponification, drying, cold drawing, recrystallization annealing, finishing, multi-station cold heading machine extrusion (including shearing blanking, heading, hollow) - surface nickel plating or galvanized - "flower" test - packaging warehousing. "Flower" test (i.e., hollow rivet condition simulation test), the expansion of rivets hollow parts and flanging, the flanging process is similar to the sheet of bore hole and flanging forming process, the hollow part of the outer force and deformation, the biggest reason for high requirement of material forming performance. When "beating the flower" turn over, sometimes it will produce the defect such as flanging and upsetting.

(1) there are five types of defects in the cold heading of low carbon steel rivets: upsetting, cracking, upset, sliding cracks and incomplete flanging.

(2) the main production process should be controlled at a low heating temperature of billet (1150 ~ 1 200 ℃) and strictly control rod spinning temperature at 910 ~ 930 ℃, the wire rod products with moderate grain size, with 6 ~ 6. It is advisable to level 5; Improve the surface quality of the rod.

(3) in the aspect of material use should be by adjusting the drawing deformation and the corresponding annealing technology is applied in the proper process, and improve the performance of cold heading forming on the materials, reduce or eliminate flanging crack, under the heading and other cold heading forming defect in the flange.