Manufacturing process for stress relaxation-resistant high-strength bolt

A technology of high-strength bolts and manufacturing technology, applied in the direction of screws, threaded fasteners, connecting components, etc., can solve the problems of long bolt deformation, stress relaxation, etc. To resolve the effect of deformation

Inactive Publication Date: 2009-07-22
NANJING INST OF TECH +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The main problem with this process is that the deformation of long bolts during quench

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] In the actual work of the present invention, it includes quenching and tempering treatment process, drawing process, cold heading thread blank diameter / rod part / hexagonal head process, thread rolling process, stabilization treatment process, surface treatment process, shot peening Strengthening or head fillet rolling strengthening process and flaw detection process, conduct conventional quenching and tempering treatment on the wire rod of specified material, control its strength to be 75% of the strength of the final product, and control the tensile strength of the wire rod to 750MPa for grade 10.9 bolts; Grade 12.9 bolts, the tensile strength of the control wire is 900MPa. The above-mentioned quenched and tempered wire rod is drawn and cold-headed with a thread blank diameter (bolt shank or hexagonal head), and the amount of drawing deformation (that is, the area reduction rate) of the shank is controlled at 20%. Improve and guarantee its strength. Then carry out thre...

Embodiment 2

[0019] In the practical application of the present invention, it includes quenching and tempering treatment process, drawing process, cold heading thread blank diameter / rod part / hexagonal head process, thread rolling process, stabilization treatment process, surface treatment process, shot peening Strengthening or head fillet rolling strengthening process and flaw detection process, the wire rod of the specified material is subjected to conventional quenching and tempering treatment, and its strength is controlled to be 70% of the strength of the final product. For 10.9 grade bolts, the tensile strength of the wire rod is controlled to 700MPa; Grade 12.9 bolts, the tensile strength of the control wire is 840MPa. The above-mentioned quenched and tempered wire rods are drawn and cold-headed to the diameter of the thread blank (cold-headed bolt shank or hexagonal head), and the area reduction rate of the shank is controlled at 25%. Then carry out thread rolling and stabilization ...

Embodiment 3

[0022] In the practical application of the present invention, it includes quenching and tempering treatment process, drawing process, cold heading thread blank diameter / rod part / hexagonal head process, thread rolling process, stabilization treatment process, surface treatment process, shot peening Strengthening or head fillet rolling strengthening process and flaw detection process, conduct conventional quenching and tempering treatment on the wire rod of specified material, control its strength to be 78% of the strength of the final product, and control the tensile strength of the wire rod to 780MPa for grade 10.9 bolts; Grade 12.9 bolts, the tensile strength of the control wire is 936MPa. The above-mentioned quenched and tempered wire rods are drawn and cold-headed with thread blank diameter (cold-headed bolt shank or hexagonal head), and the area reduction rate of the shank is controlled at 18%. Then carry out thread rolling and stabilization treatment, the heating temperat...

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Abstract

The invention relates to a manufacturing process of a high-strength bolt resisting stress relaxation. The manufacturing process sequentially comprises working procedures of quenching and tempering, drawing, cold upsetting thread billet inner diameter/rod part/hexagon head, thread rolling, stabilizing, surface treatment and peening or round corner rolling strengthening and defect detection. In the quenching and tempering working procedure, wire rod strength is finally controlled at 85-65% of a finished product; in the drawing working procedure, the drawing deformation is controlled at 15-40%, in the stabilizing working procedure, the heating temperature is 200-450 DEG C, the temperature is kept for 0.5-4h and the bolt is taken from the furnace for air cooling. The high-strength bolt resisting stress relaxation has the beneficial effects of being adapted to the development of machinery industry, especially automobile industry, solving a deformation problem of a long bolt in quenching treatment, further improving the performance of resisting stress relaxation during practical use, and being capable of further increasing the strength of the bolt up to 1300MPa.

Description

technical field [0001] The invention relates to a manufacturing process of high-strength bolts, in particular to a manufacturing process of stress-relaxation-resistant high-strength bolts. Background technique [0002] High-strength bolts are the most widely used fasteners in the machinery industry. At present, most high-strength bolts above grade 8.8 in China are produced by medium carbon steel or medium carbon steel alloy steel (such as 35 steel, 40Cr35Cr, 35CrMo, 42CrMo, 42CrMoVNb, etc.). The manufacturing process of strength bolts mainly includes drawing process, cold heading thread blank diameter / rod / hexagonal head process, thread rolling process, quenching and tempering process, surface treatment process and flaw detection process in order. The most important process is quenching and tempering treatment, both quenching + high temperature tempering treatment. The main problem of using this process is that the deformation of long bolts during quenching is difficult to o...

Claims

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Application Information

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IPC IPC(8): F16B35/04C21D1/18C21D7/06
Inventor 惠卫军赵秀明蔡璐
Owner NANJING INST OF TECH
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