Production process of high-residual-stress valve spring

Abstract

The invention discloses a production process of a high-residual-stress valve spring. The process comprises the following steps of spring rolling, wherein 55CrSi or 50CrVA spring steel wire materials are adopted as a blank; isothermal quenching; salt bath tempering, wherein the temperature of a salt pool is controlled between 400 DEG C and 440 DEG C, and heat preservation is carried out for a period; cleaning and drying; spring grinding; chamfering, wherein the two ends of a semi-finished spring obtained after spring grinding treatment are chamfered, burrs are removed, and the assembling requirements of customers are met; shot blasting of two times, wherein rough blasting is carried for the first time, a high residual stress value is obtained, fine blasting is carried out for the second time, and a deep residual stress value is obtained; hot press shaping; subsequent settling. Therefore, the high-residual-stress valve spring is manufactured. According to the production process, residual tension in the spring rolling process can be eliminated, the original mechanical performance of the materials can be kept, the high and deep residual stress can be obtained in the shot blasting process, the valve spring can be applied to high-stress-amplitude occasions, and the miniaturization requirement of an engine is met.

Description

technical field [0001] The invention relates to a production process of a high residual stress valve spring, which is a process flow for manufacturing the valve spring. Background technique [0002] At present, the valve train is an important part of the engine, and the control of the valve by the cam is one-way, and the valve spring must be provided to ensure the return of the valve; when the valve is closed, the valve spring must ensure the closure between the valve and the valve seat Sealing; during the negative acceleration phase of the cam, the valve spring must keep the valve from breaking away from the control of the cam. Valve springs are subjected to high-frequency alternating loads during work. Once fatigue failure occurs, the entire engine often needs to be replaced. Therefore, the valve spring is the same as the main parts of the engine such as the cylinder block, crankshaft and connecting rod. It is required not to break during the warranty period, and it has h...

AI Technical Summary

Problems solved by technology

The traditional valve spring manufacturing process is as follows: use oil-hardened steel wire, and it is made by spring coiling, stress relief annealing, spring grinding, chamfering, shot peening and hot pressing; in the stress relief tempering process, the coil cannot be completely removed. Part of the tensile stress generated by the spring continues to remain on the surface of the steel wire, causing the valve spring to fail to obtain high residual stress during the shot peening process, which improves the service life of the valve spring; in addition, the surface hardness of the steel wire will decrease, and the tensile strength of the corresponding spring steel wire It will drop by 100~200MPa

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