Machining technology of integrally-formed multi-thread bolt

Abstract

The invention discloses a machining technology of an integrally-formed multi-thread bolt. The technology comprises the following steps of a cold heading working procedure, wherein a wire rod is cut off, and is headed into a screw blank, and a head portion, cross recess (or other head-type) thread billet diameters and rod lengths, and head lower fillets are formed; a thread rolling working procedure, wherein threads are rolled out of the cold-heading blank, a thread rolling machine is adopted to machine threads on a screw rod, a high-tooth thread rolling plate and a low-tooth thread rolling plate are arranged on the thread rolling machine, high threads and low threads are formed at a time, the height of the high threads ranges from 8.0 mm to 8.5 mm, and the height of the low threads ranges from 5.5 mm to 6.5 mm; heat treatment, wherein, a bolt is quenched by quenching oil at the temperature of 800 DEG C+ / -10 DEG C, and two-time tempering is carried out on the quenched bolt; carburizing treatment, wherein a carburizing agent is conveyed to a tempering furnace, and carburizing treatment is carried out for 50 minutes to 120 minutes at the temperature ranging from 1100 DEG C to 1150 DEG C; and finally, cleaning and air drying are carried out, and the finished bolt is obtained. According to the technology, the high threads and the low threads can be rolled out at a time. The machining technology is simple, and the qualified rate of the finished product is high.

Description

technical field [0001] The invention relates to the field of bolts for transmission devices, in particular to a processing technology for one-time forming multi-thread bolts. Background technique [0002] The bolt production method in the prior art includes production processes such as plate element, annealing, pickling, wire drawing, forming, tapping, heat treatment, and surface treatment. For high-strength nuts that require high strength, the current heat treatment process is carburizing or cyanide + quenching and tempering, and a complete annealing process of 850-900 ° C for 10 hours, but the bolts produced by this process are quenched. The reduction of area is relatively large, the deformation rate is large, the matching rate with the nut is low, and the scrap rate sometimes exceeds 10%; and the existing bolts are prone to rust spots after long-term use. Contents of the invention [0003] The technical problem to be solved by the present invention is to provide a one-...

AI Technical Summary

Problems solved by technology

For the high-strength nuts that require high strength, the current heat treatment process is to use carburizing or cyanide + quenching and tempering processes, and a complete annealing process with a temperature of 850-900 ° C for 10 hours, but the bolts produced by this process are hardened after quenching. The shrinkage rate of the section is large, the deformation rate is large, the matching rate with the nut is low, and the scrap rate sometimes exceeds 10%; and the existing bolts are prone to rust spots after long-term use