Embossed Piston Flow Paths for Tight Bypass Tolerances
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Solution Overview
Problem
Existing methods for producing pistons with small bypasses face challenges due to large process-related tolerances, which affect the precision and effectiveness of damper characteristics, especially in sintered pistons where tolerances can be as high as ISO IT 7, and are further compromised by surface treatments like deburring.
Innovation Solution
A method involving pressing a material into a piston mold, followed by sintering if necessary, and then using an embossing tool with a raised rotationally symmetrical structure to create a smooth surface and precise flow paths, allowing for reduced production tolerances and controlled flow paths, thereby improving damper characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If machining or pressing is used to create bypasses in pistons, then the piston can be produced, but large process-related tolerances (ISO IT 7 to IT 6) affect the precision of small bypasses
Solution Approach 1:
The bypasses are pre-formed during the pressing process by incorporating precision pressing elements into the mold, rather than attempting to machine them afterward. This preliminary formation of the bypasses with controlled tolerances directly addresses the manufacturing precision issue while avoiding the complexity of subsequent machining operations.
Solution Approach 2:
The patent replaces traditional machining operations with a precision pressing process. By using pressing elements that directly form the bypasses during material compaction, the method eliminates the need for post-pressing machining, thereby achieving tighter tolerances (IT 3 to IT 6) without increasing overall production complexity.
2Ease of manufacture
If surface treatment like vibratory grinding or shot peening is applied after pressing, then deburring is achieved, but the tolerances of the bypasses are negatively influenced
Solution Approach 1:
The pressing elements are designed to pre-form smooth bypass surfaces during the initial pressing operation, eliminating the need for subsequent deburring operations. By performing the surface finishing action during the primary forming process, the patent prevents tolerance degradation that would occur with post-pressing surface treatments.
Solution Approach 2:
The patent extracts the deburring function from the post-pressing process and integrates it into the pressing operation itself. By incorporating surface-forming capabilities into the pressing elements, the harmful deburring step is eliminated, preserving bypass tolerances while still achieving the necessary surface quality.
3Productivity
If small bypasses are produced by traditional methods, then the damper can be assembled, but the large process tolerances lead to inconsistent damper characteristics
Solution Approach 1:
The bypass geometry is predetermined and pre-formed with high precision during the pressing operation using specially designed pressing elements. This preliminary precision formation ensures consistent damper characteristics across mass production while maintaining industrial productivity, as no additional precision-critical steps are required afterward.
Solution Approach 2:
The patent changes the critical parameter of bypass formation from post-pressing machining or sintering to precision pressing. By controlling the pressing parameters (pressure, temperature, element geometry) during material compaction, the method achieves tight tolerances (IT 3 to IT 6) that ensure consistent damper characteristics while maintaining mass production capability.
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 method enables the production of pistons with lower production tolerances, specifically in the range of IT 3 to IT 6, facilitating more precise and homogeneous flow paths, which enhances the damper's performance and allows for industrial series production.
Implementation Method 1
a. Producing the piston by pressing a material into a piston mold
Implementation Method 2
b. Smoothing the surface of the piston and/or pressing at least one flow path into the piston, by an embossing tool
Implementation Method 3
If the previously produced piston consists of a sinterable powder, the piston previously produced in the pressing process is sintered in a subsequent sintering process under the influence of temperature and/or pressure
Data Source
AI summary
A piston and a method for producing a piston which can be secured to a piston sliding unit is provided. The piston sliding unit can be moved along its longitudinal axis in a cylinder. The piston includes a disc-shaped base body, wherein the piston is suitable and intended to seal two regions of the cylinder filled with a medium against one another. The method includes the following steps: a) producing the piston by pressing a material into a piston mold; b) smoothing the surface of the piston and/or pressing at least one flow path into the piston, by an embossing tool, which has a raised and rotationally symmetrical structure.