Forged Piston with Welded Ring Section for Complex Combustion Geometry
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Solution Overview
Problem
Existing methods for producing pistons are limited to specific structures, such as those with a piston head and skirt, and cannot accommodate complex geometries or different material compositions for the ring section, restricting the variety of piston designs that can be realized.
Innovation Solution
The method involves fully producing the contour of the combustion depression during the initial forging of the piston main body blank, allowing for the use of different materials and enabling the creation of reinforced ring sections, with optional pre-machining of cooling duct regions and boss bores to achieve specific piston geometries and compression heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the blank of the piston main body is finished by forging in the entire region of the combustion depression, then the manufacturing process is simplified and secondary machining is eliminated, but the piston structure is limited to simple geometries and cannot accommodate complex combustion depression contours
Solution Approach 1:
The piston is divided into two separate blanks: a piston main body blank and a piston ring section blank. These blanks are produced independently through forging, allowing each to be optimized for its specific structural requirements. The piston main body blank can accommodate complex combustion depression contours while the ring section is separately formed and later joined, resolving the contradiction between manufacturing simplicity and structural versatility.
Solution Approach 2:
The contour of the combustion depression is fully produced during the initial forging of the piston main body blank, before any assembly or welding operations. This preliminary formation of the complex geometry in the blank stage enables subsequent simple joining operations while achieving the desired complex final structure, thus maintaining ease of manufacture while enabling structural variety.
2Adaptability or versatility
If the piston upper part comprises only the piston head and the piston lower part comprises only the piston skirt, then the production method can be applied, but complex piston structures with reinforced ring sections made of different materials cannot be realized
Solution Approach 1:
Different regions of the piston are made from different materials with locally optimized properties. The piston ring section can be produced from a material specifically suited for high-wear ring groove applications, while the piston main body uses a material optimized for combustion chamber requirements. This local differentiation enables reinforced ring sections with different material compositions while maintaining manufacturing feasibility through separate blank production and joining.
3Manufacturing precision
If cooling duct regions are finish-machined after welding of the blanks, then the cooling ducts can be precisely formed, but the welded piston body becomes difficult to handle and the process complexity increases
Solution Approach 1:
Cooling duct regions are formed into the piston main body blank and inlet/outlet openings are created before the welding operation. This preliminary machining of cooling ducts in the blank stage, when the part is still easily handleable, avoids the difficulty of machining after welding while maintaining precision through controlled forming and machining operations on the blank.
Solution Approach 2:
The cooling duct system is integrated into the piston main body blank as a separate feature that is formed during blank production and pre-machining. This segmentation of the cooling duct formation process from the final assembly allows precise cooling duct creation in the blank stage while keeping the welding and final assembly processes simpler and more manageable.
4Manufacturing precision
If the boss bores are formed into the piston bosses after the piston crown has been finish-machined, then the predetermined compression height is easily achieved, but the handling and positioning precision during machining may be compromised
Solution Approach 1:
Instead of forming boss bores before finish-machining the piston crown, the sequence is inverted: the piston crown is finish-machined first to establish precise reference surfaces, then the boss bores are formed. This inversion allows the finish-machined crown to serve as a precise reference for positioning the boss bores, ensuring accurate compression height while maintaining ease of operation through a logical machining sequence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of pistons with complex geometries and varied material compositions, eliminating the need for secondary machining of the combustion depression and allowing for the creation of reinforced ring sections, thereby expanding design possibilities and improving handling and performance.
Implementation Method 1
The blank may be forged by hot working at 1200° C. to 1300° C.
Implementation Method 2
The blank of the piston main body is finished by forging in the entire region of the combustion depression
Data Source
AI summary
A method for producing a piston for an internal combustion engine may include the steps of: producing a first blank corresponding to a piston main body via a deformation process; producing a second blank corresponding to a piston ring part via at least one of a deformation process and a casting process; pre-machining the first blank and the second blank, and finishing a welding surface of the first blank and a welding surface of the second blank via machining; connecting the first blank and the second blank via welding the welding surface of the first blank to the welding surface of the second blank to form a piston body; and performing at least one of a secondary machining process and a finish machining process on the piston body to produce the piston.