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Method for improving tensile and compression fatigue life of metal workpiece and workpiece made by the method

A metal workpiece, fatigue life technology, applied in the field of mechanical manufacturing and processing, can solve problems such as fatigue fracture of metal workpieces

Active Publication Date: 2019-05-14
CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of this, the purpose of the present invention is to provide a method for improving the tensile and compressive fatigue life of metal workpieces and the workpiece produced by the method, which can solve the technical problem of fatigue fracture of metal workpieces in the product life cycle, and improve the tensile and compressive fatigue life of metal workpieces. Fatigue life, effectively avoiding the occurrence of safety and economic losses caused by workpiece fracture

Method used

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  • Method for improving tensile and compression fatigue life of metal workpiece and workpiece made by the method
  • Method for improving tensile and compression fatigue life of metal workpiece and workpiece made by the method
  • Method for improving tensile and compression fatigue life of metal workpiece and workpiece made by the method

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Embodiment 1

[0050] A method for improving the tension-compression fatigue life of metal workpieces is specifically applied to the embodiment of fastening workpieces (here, bolts are used as an example for fastening workpieces), comprising the following steps:

[0051] In the length direction of bolt 1 (as attached figure 1 , 2 , 3 and 4 in the direction indicated by L) to carry out strong tension treatment on bolt 1, that is, to apply a set tensile force exceeding its yield strength but lower than its tensile strength, when the tensile force applied to bolt 1 reaches the expected setting After pulling the tension, remove the tension to improve the tension-compression fatigue characteristics of the bolt 1. The time for the strong pulling treatment is to remove the pulling force as soon as the expected pulling force is reached, or it can be kept for a certain period of time (called holding time) after reaching the expected pulling force as required and then remove the pulling force.

[00...

Embodiment 2

[0059] A bolt 1 manufactured by the method described in Embodiment 1, the bolt 1 includes a bolt body 3 and a bolt head 2 arranged at one end of the bolt body 3 .

Embodiment 3

[0061] For bolt 1, choose M10×85 grade 8.8 carbon steel bolts, the yield strength of M10×85 grade 8.8 carbon steel bolts is 37.1KN, and the tensile strength is 46.4KN. Apply a pulling force of 40KN to the bolt 1 through a tensioning machine, and remove the tensioning force when the tensioning force applied by the tensioning machine reaches the expected pulling force (that is, the pulling force of 40KN). After the 40KN strong tension treatment, under the pretightening force of 5.5KN and the alternating load condition of ±5.5KN, compared with the bolt 1 without treatment, the tension and compression fatigue life of the bolt 1 after the strong tension treatment Got a 12x improvement.

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Abstract

The invention discloses a method for prolonging the tension-compression fatigue life of a metal workpiece and the workpiece manufactured according to the method. The method comprises the step that set tension higher than the yield strength and lower than the tension strength of the metal workpiece is applied to the metal workpiece in the operating state in the tension stress bearing direction. The tension applied to the metal workpiece is relieved after reaching the set tension so that the tension-compression fatigue characteristic of the metal workpiece can be improved. By applying the tension higher than the yield strength of the metal workpiece to the metal workpiece, pressure stress is formed on the stress concentration portion when the metal workpiece does not bear external force. By applying the tension, stress concentration formed on the stress concentration portion under the rated condition of the metal workpiece is weakened compared with stress concentration generated before the metal workpiece bears the tension. By means of the method for prolonging the tension-compression fatigue life of the metal workpiece and the workpiece manufactured according to the method, the technical problem of fatigue fracture of metal workpieces within the product life cycle can be solved, the tension-compression fatigue life of the metal workpiece is prolonged, safety loss, economic safety and the like caused by workpiece fracture are effectively avoided, and meanwhile metal workpieces having potential quality issues can be removed in advance.

Description

technical field [0001] The invention relates to the field of mechanical manufacturing and processing, in particular to a method for improving the tension-compression fatigue life of a metal workpiece, and the workpiece produced by the method. Background technique [0002] As a metal workpiece with high local stress concentration, fasteners, such as bolts, are usually prone to fatigue damage under tensile conditions, which brings safety hazards and economic losses to the products they are applied to. At the same time, fatigue damage is also very easy to occur for locally high-stress connected workpieces such as locomotive wheels, welded workpieces, and workpieces with initial defects. Take a bolt as an example. A bolt is a mechanical part widely used in various fields. As a commonly used fastener, it is often used to cooperate with a nut to fasten two parts with through holes. As we all know, most of the damage of bolts is fatigue damage, and bolts are a kind of parts with m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D7/02
CPCC21D7/02
Inventor 许倍倍张文辉严允
Owner CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST