Casting Mold Groove Geometry for Flexible Piston Demolding
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Solution Overview
Problem
Existing casting molds for internal combustion engine pistons face challenges in demolding due to undercuts caused by waffle patterns, limiting demolding direction and potentially damaging the cast piston.
Innovation Solution
A casting mold with a surface texture formed by grooves of specific dimensions (0.2 mm < t < 0.5 mm depth, 0.02 mm < b < 0.05 mm width, and 0° < α < 10° inclination) that allows demolding up to 90° parallel to the texture, preventing undercuts and enabling flexible demolding directions, while maintaining effective de-airing and origin identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a waffle pattern surface texture is introduced in the pull direction of the casting mold, then air removal and casting material flowability are improved, but demolding becomes restricted to specific directions and undercuts are formed
Solution Approach 1:
The groove inclination angle α is changed from the conventional large angle (producing undercuts) to a small angle between 0° and 10°. This parameter change eliminates undercut formation while maintaining the waffle pattern's air removal functionality, enabling demolding in almost any direction including up to 90° parallel to the surface texture.
Solution Approach 2:
Instead of forming undercuts that restrict demolding, the groove geometry is inverted to create outwardly inclined walls that facilitate demolding. The grooves are designed with inclination angles that prevent material penetration while allowing the casting blank to be removed parallel to the surface texture.
2Object-generated harmful factors
If grooves with larger depth and width are used to improve air removal, then de-airing efficiency increases, but casting material penetrates into the grooves causing defects
Solution Approach 1:
The groove dimensions are optimized with depth t between 0.2 mm and 0.5 mm and width b between 0.02 mm and 0.05 mm. The groove inclination angle α is set between 0° and 10°. These parameter changes create grooves that are sufficient for air removal but too shallow and narrowly inclined for casting material to penetrate, preventing defects.
3Adaptability or versatility
If the groove walls are inclined outward with small angles, then demolding flexibility is improved, but the structural strength of the surface texture may be reduced
Solution Approach 1:
The groove depth is optimized to 0.2-0.5 mm, providing sufficient structural strength while maintaining the outward inclination. The combination of moderate depth and small inclination angle (0°-10°) ensures that the surface texture retains its mechanical integrity while enabling demolding in almost any direction.
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
The solution allows for flexible demolding in almost any direction, prevents casting material penetration and undercut formation, and enhances air removal and origin verification, ensuring a high-quality and cost-effective casting process.
Implementation Method 1
the grooves have groove walls (6) which are inclined outward... it makes it possible to demold a cast piston (2) in almost any direction, in particular even up to approximately parallel to a surface of the surface texture (5)
Implementation Method 2
a coating, in particular a release agent, is applied to the surface texture... suitable options include metallic or ceramic coatings or combinations thereof
Data Source
AI summary
A casting mold for casting a piston for an internal combustion engine may include a mold body having a surface texture in a region corresponding to a subsequent internal surface of a piston skirt. The surface texture may be defined by a plurality of grooves. The plurality of grooves may have the following dimension: a depth of 0.2 mm<t<0.5 mm, a width of 0.02 mm<b<0.05 mm, and at least two groove walls which are inclined outwardly at 0°<α<10°.