Friction Welded Piston Manufacturing with Variable Combustion Bowl Depth
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Solution Overview
Problem
The existing methods for producing pistons with large and shallow combustion bowls face difficulties in using a forging process to create a suitable joining surface for friction welding, as the joining surface resembles the end of a tube, making it challenging to produce pistons with varying combustion bowl depths using the same blanks.
Innovation Solution
A method involving pre-machining the piston base body and ring element blanks to create widened joining surfaces, allowing for friction welding and subsequent finishing to produce pistons with varying combustion bowl depths, while using heat-treated steel to create a hardened heat-affected zone for increased durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional forging process is used to create a joining surface resembling the end of a tube, then the piston base body can be produced, but it becomes difficult to produce pistons with varying combustion bowl depths using the same blanks
Solution Approach 1:
The invention changes the geometric parameters of the joining surface by widening it in the direction of the combustion bowl bottom area. This parameter change transforms the joining surface from a tube-end shape to a plate-like shape, enabling both traditional and varied combustion bowl designs to be produced from the same blank while maintaining ease of manufacture
Solution Approach 2:
The invention segments the joining surface into distinct functional areas: a widened inner joining surface for friction welding and a remaining free partial area that accommodates different combustion bowl depths. This segmentation allows the same blank to serve multiple design requirements
2Ease of manufacture
If the inner joining surface is widened to enable forging process, then the blank can be produced by forging, but the joining surface becomes larger than needed for friction welding
Solution Approach 1:
The invention applies local quality by creating a non-uniform joining surface where only the necessary area participates in friction welding. The widened surface provides sufficient area for forging while the specific geometry ensures that only the required portion is active during welding, with the excess area remaining free for subsequent combustion bowl formation
3Productivity
If friction welding is performed with traditional joining surfaces, then joining can be achieved, but friction welding beads accumulate and require additional removal processes
Solution Approach 1:
The invention performs preliminary action by pre-widening the joining surface during blank preparation before friction welding. This preliminary geometric modification prevents bead accumulation during the welding process itself, eliminating or reducing the need for subsequent bead removal operations and thereby improving productivity
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
Enables the production of pistons with different combustion bowl depths using the same blanks, reduces manufacturing costs, and eliminates the need for additional hardening processes by utilizing the heat-affected zone for wear-resistant areas.
Implementation Method 1
the blanks are joined by means of a friction welding process
Implementation Method 2
the blanks are heat-treated steel or precipitation-hardening steel
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a method for producing a piston (10, 110) for an internal combustion engine, having a main piston body (11, 111) and a piston ring element (12, 112), wherein the main piston member (11, 111) comprises at least one piston skirt (15, 115) and at least one bottom region (27, 127) of a combustion recess (21, 121). The piston ring element (12, 112) comprises a piston crown (19, 119), at least one wall region (28, 28) of the combustion recess (21, 121), a circumferential fire land (22, 122) and at least one part of a circumferential ring part (23, 123) provided with annular grooves. The main piston body (11, 111) and the piston ring element (12, 112) form a circumferential closed cooling duct (24, 124). The method is characterised by the following method steps: (a) providing a blank (11', 111', 211') of the main piston body (11, 111), in which an outer circumferential joining surface (29, 129, 229) and an inner circumferential joining surface (31, 131, 231), which is widened in the direction of the bottom region (27, 127) of the combustion recess (24, 124), as well as a circumferential lower cooling duct part (24a, 124a, 224a) between the two joining surfaces (29, 31; 129, 131; 229, 231) are rough-machined, (b) providing a blank (12', 112', 212') of the piston ring element (12, 112) in which an outer annular joining surface (32, 132, 232) and an inner annular joining surface (33, 133, 233) as well as a circumferential upper cooling duct part (24b, 124b, 224b) between the two joining surfaces (32, 33; 132, 133; 232, 233) are rough-machined, (c) joining the blank (11', 111', 211') to the blank (12', 112', 212') via the joining surfaces (29, 129, 229; 31, 131, 231; 32, 132, 232; 33, 133, 232) thereof in order to form a piston blank (10', 110') in such a manner that at least in the bottom region (27, 127) of the combustion recess (24, 124) a sub-region (34, 134, 234) of the widened joining surface (31, 131, 231) of the blank (11', 111', 211') remains blank, (d) post-machining and/or finishing the piston blank (10', 110') to form a piston (10, 110) whilst removing the sub-region (34, 134, 234) of the widened joining surface (31, 131, 231).