Cold heading forming technology of eccentric flange nut with bosses and combined mold applied to cold heading forming technology

Abstract

The invention discloses a cold heading forming technology of an eccentric flange nut with bosses and a combined mold applied to the cold heading forming technology. The cold heading forming technologyof the eccentric flange nut with the bosses comprises the steps of a blanking process, a shaping process, a punching process, and three heading forming processes and an eccentric flange forming process sequentially following the shaping process; in the three heading forming processes, a forward flange section, a hexagonal prism section, and a boss section are sequentially formed in a blank threetimes, kidney-shaped counterbores with sequentially increased depths are formed in the blank three times, and kidney-shaped locating holes with sequentially increased depths are formed in the blank three times; the forward flange section is coaxial with the hexagonal prism section and the boss section; and in the eccentric flange forming process, the blanking process is conducted on the forward flange in the axial direction to form the desired eccentric flange section. The cold heading forming technology of the eccentric flange nut with the bosses has the advantages that the technology is simple, the production efficiency is greatly improved, the production process is stable, the stripping is convenient, the service life of the mold is prolonged, the flange face of the formed eccentric flange nut is uniform and attractive, and the product precision is high.

Description

technical field [0001] The invention relates to the technical field of manufacturing special-shaped nuts used in automobiles, in particular to a cold heading forming process of an eccentric flange nut with a boss and a combined mold used therein. Background technique [0002] With the development of the automobile manufacturing industry, the demand for high-quality and complex special-shaped fasteners is increasing. The eccentric nut of the rear lower arm of the automobile is used as a load fastener on the automobile. The eccentric nut includes an eccentric flange section, a hexagonal prism section, and a boss section in the axial direction, and a waist-shaped hole runs through the inner axial direction; the traditional preparation process of the eccentric nut of the lower swing arm of the automobile is a hexagonal nut with a boss and a The gasket is welded, and the gasket constitutes the required eccentric flange segment. However, due to the defects of the welding process i...

AI Technical Summary

Problems solved by technology

[0002] With the development of the automobile manufacturing industry, the demand for high-quality and complex special-shaped fasteners is increasing. The eccentric nut of the rear lower arm of the automobile is used as a load fastener on the automobile. The eccentric nut includes an eccentric flange section, a hexagonal prism section, and a boss section in the axial direction, and a waist-shaped hole runs through the inner axial direction; the traditional preparation process of the eccentric nut of the lower swing arm of the automobile is a hexagonal nut with a boss and a The gasket is welded, and the gasket constitutes the required eccentric flange segment. However, due to the defects of the welding process itself, the products formed by welding have the problems of unsmooth internal streamlines and insufficient strength; and due to the required forming The size of the nut is usually small, therefore, the increase of the welding process will cause inconvenient processing and increase the processing time, the production efficiency is not high, and it is not good for the improvement of the production efficiency of the enterprise

[0003] In response to the above problems, there has been a cold heading process in the industry that adopts the integral molding process of gaskets and hexagonal nuts to realize the cold heading process of eccentric flange nuts with complete forging streamlines, high strength and high processing efficiency. For example, in February 2016 The Chinese Invention Patent Application Publication Document CN105290300A published on the 3rd records a cold heading process for chassis eccentric nuts and a mold structure for forming special-shaped holes. type process, and discloses that its eccentric flange is formed by upsetting three times. This process has the following problems: (1) its eccentric flange is directly formed, so the die thimble used is relatively The eccentric setting will cause the thimble of the die to be subject to a large bending and torsional stress during the upsetting process, which will easily cause wear and fracture of the thimble of the die; Stretching and forming the stretching hole makes the blank hold too much force on the thimble of the main mold after the stretching hole is formed. The push tube on the outer periphery of the thimble of the main mold performs the ejection operation on the blank. The push tube needs to be set in each mold used in the steps from the third step to the seventh step in the application document, and because the wall of the push tube Therefore, when the upper end of the billet is upset by the thimble of the die, the push tube supported by the lower end of the billet is prone to swelling, deformation, cracking or jamming, which will cause the push tube to be unable to use normally. It affects the function of the ejector pin of the main mold, which makes the mold prone to processing failures during production, resulting in low product yield and low production efficiency; (3) In the process of direct forming of the eccentric flange, there are different volumes at different positions of the blank and different parts. The difference in the forging flow rate in the radial direction will cause the part of the flange that has no time to flow to be extruded from the sidewall gap between the die thimble and the cavity when the flange is extruded, so that it will be on the flange end surface of the blank The phenomenon of protruding thorns not only leads to local material loss in the flange, but also makes the forging streamline of the flange uneven, the strength of the flange on the formed nut is uneven, and the cylindricity of the flange is uneven. Large, affecting the accuracy and quality of the product

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