Laser welding forming internal cooling oil channel based steel piston and machining method thereof

Abstract

The invention discloses a steel piston with an inner cooling oil channel formed by laser welding and a processing method thereof. The steel piston includes a piston body and an annular sealing plate. The piston body is provided with an inner cooling oil passage and a combustion chamber on the piston head. The upper end of the inner cooling oil passage is provided with an annular opening. The annular opening is located at the top of the piston head. The annular sealing plate It is embedded in the annular opening and fixed by laser welding, and the upper end of the inner cooling oil passage is sealed. The method includes the following steps: S1: parts processing; S2: laser welding assembly: including preheating the annular sealing plate and the annular opening; forming an interference fit when the annular sealing plate and the annular opening are cooled to normal temperature; The sealing plate is preheated as a whole before welding; laser welding is performed on the annular sealing plate and the inner and outer ring interfaces of the annular opening; slow cooling after welding; S3: heat treatment; S4: post-processing. It has the advantages of convenient processing, can effectively improve the cooling performance of the piston, prolong the service life, reduce the weight of the piston and improve the working performance.

Description

technical field [0001] The invention relates to a steel piston and a processing technology thereof, in particular to a steel piston formed on the basis of laser welding to form an internal cooling oil passage and a processing method thereof. Background technique [0002] For the emission upgrade of vehicle diesel engines, the piston is a key component. Steel structure pistons replace aluminum structure pistons, which is one of the important means for vehicle diesel engines to meet Euro IV, Euro V, and Euro VI emission standards. In recent years, all-steel pistons have been widely used in vehicle diesel engines. All-steel pistons are forged, but the inner cooling oil cavity of all-steel pistons is poorly processed, difficult to process, low in efficiency and high in cost. Around the molding of the internal cooling oil cavity, there are various solutions at home and abroad, such as the method for manufacturing the integral piston of the internal combustion engine disclosed by ...

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Problems solved by technology

However, there are also the following deficiencies: first, the residue of the friction welding flash in the internal cooling oil channel is relatively large, which affects the cooling effect, and also increases the weight of the piston head, which affects the performance of the piston; the second is that the friction welding axial control tolerance Limitation (axial tolerance ±0.25mm), the effective height of the internal cooling oil chamber has a large tolerance, which affects the control of the axial dimension of the piston head; the third is that there are process defects in the open trapezoidal welding surface. In the first stage, the upsetting force loading is limited by the open trapezoidal welding surface. Excessive loading will lead to deformation of the welding surface. If the upsetting force is insufficient, the quality of the welded joint formed after the solid phase connection of the weld will be unreliable.

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