Piston Combustion Depression Volume Control via Segmented Forging
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Solution Overview
Problem
Existing methods for producing pistons result in changes to the microstructure and volume of combustion depressions due to local heating during welding, leading to deviations from predefined volume values, especially in complex geometries, making secondary machining impossible.
Innovation Solution
The method involves forming excess material in the dome region of the combustion depression during deformation processes, allowing for precise removal to achieve the predetermined volume without altering the geometry outside the dome region, and incorporating pre- and finish-machining steps to ensure accurate volume and geometry.
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 contour of the combustion depression is not involved in secondary machining processes, but the local heating during welding causes changes in microstructure and volume of the combustion depression, leading to deviations from predefined volume values
Solution Approach 1:
The combustion depression is divided into two regions: a dome region where excess material is intentionally formed and a remaining region that is fully produced by forging. This segmentation allows selective machining only in the dome region after welding, preserving the precision of the fully forged regions while correcting volume deviations caused by welding heat.
Solution Approach 2:
Excess material is deliberately formed in the dome region during the forging process before welding occurs. This preliminary action anticipates the volume increase caused by welding heating and prepositions material that can be removed later to compensate for the welding-induced expansion.
2Manufacturing precision
If excess material is formed in the dome region and removed after welding to achieve predetermined volume, then the volume precision is improved, but additional machining steps are required
Solution Approach 1:
Instead of machining the entire combustion depression, only the dome region requiring volume adjustment is subjected to additional machining. The remaining region maintains its forged precision without further intervention. This localized approach minimizes the complexity increase while achieving the required volume precision.
3Manufacturing precision
If the combustion depression geometry is manipulated outside the dome region to compensate for volume changes, then volume precision can be achieved, but the fully produced contour advantage is lost
Solution Approach 1:
The problem of volume compensation is extracted from the entire combustion depression and concentrated solely in the dome region. By isolating the volume adjustment task to this specific area, the solution preserves the advantage of fully forged contours in the remaining region while achieving precise volume control through localized machining.
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 ensures the combustion depression volume remains within predefined tolerance ranges, even for complex geometries, by accurately setting the volume post-welding without requiring additional secondary machining outside the dome region.
Implementation Method 1
during the production of the blank of the piston main body by deformation processes
Implementation Method 2
the welding of the blanks results in a change in the microstructure and the dissipation of stresses in the material
Implementation Method 3
the local heating of the piston body during the welding of the blanks
Implementation Method 4
in step e), such an amount of the excess material in the dome region of the combustion depression is removed as to result in a predetermined volume 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 piston main body from a first blank via a deformation process; producing a piston ring part from a second blank via at least one of a deformation process and a casting process; pre-machining the first blank and the second blank, and finish machining a welding surface of the first blank and a welding surface of the second blank; connecting the pre-machined first blank and the pre-machined second blank via a welding process to form a piston body; and performing at least one of a secondary machining and a finish machining of the piston body to produce the piston.