Pre-welding sectional type heating and press-fitting method and device

Abstract

The invention discloses a pre-welding sectional type heating and press-fitting method and device which are are used for heating and press-fitting of interference fit of an inner ring and an outer ringof an automobile engine steel piston. The method comprise the following steps that S1, the inner ring and the outer ring of the steel piston are moved to induction heating stations before press-fitting, the number of the induction heating stations is multiple, gradient heating is synchronously carried out on the inner ring and the outer ring, the temperature uniformity of the inner ring and the outer ring is guaranteed, and the temperature difference is reduced; S2, the heated inner ring and the heated outer ring are moved to a press-fitting station, and a steel piston is formed through press-fitting; and S3, the steel piston formed through press-fitting is moved to a pre-welding preheating station, and the steel piston is integrally heated to the temperature needed by welding. The multiple induction heating stations are adopted, the pre-welding heating time (only 1 / 4 of the time needed by single-station induction heating) can be greatly shortened, the temperature difference (within + / -10 DEG C) of the inner ring and the outer ring is further reduced, the steel piston part achieves the more efficient heating process, and the overall machining efficiency of the steel piston is improved.

Description

technical field [0001] The invention belongs to the technical field of welding and forming of metal materials, in particular to a method and device for segmented heating and press-fitting before welding. Background technique [0002] As the heart of fuel vehicles, the engine is undoubtedly the most important part of the transformation and upgrading of the power system. In recent years, forged steel has become the most promising new material in piston manufacturing due to its high strength, small thermal expansion coefficient, high density, and low thermal conductivity. Compared with traditional aluminum pistons, steel pistons have the advantages of less emissions, lower production costs, stronger power, lower fuel consumption, and longer oil change intervals. The industry generally believes that the steel piston industry is the only way for the piston industry in the future, and will completely replace aluminum pistons in the next 3-5 years. [0003] Since the steel piston...

AI Technical Summary

Problems solved by technology

For example, the Chinese invention patent with application number 201810508873.1 discloses a steel piston preheating device and method. The outer ring of the piston is heated before the piston is pressed, and the piston is further heated after the press. The temperature of the rings is inconsistent. Although the inner ring and the outer ring can be press-fitted, due to the large temperature difference between the inner ring and the outer ring, an oxide layer is prone to appear on the bonding surface of the press-fitting, resulting in that the subsequent laser welding effect cannot be effectively guaranteed.

In addition, because the heating of the outer ring of the piston is from a temperature close to room temperature to 160-240°C before press-fitting, it takes a long time and has a serious impact on the overall processing efficiency of the piston. How to improve the heating efficiency is an important factor to improve the production of the piston.

Furthermore, in the press-fitting process, the existing methods can only judge whether the press-fitting is qualified or abnormal. Under abnormal conditions, the outer ring may be pressed into the inner ring in a skewed state, and the quality of the press-fitting cannot be guaranteed.

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