Cold-Worked Brake Piston With Local Wall Thickening
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Solution Overview
Problem
Existing brake pistons for service brakes are not suitable for repurposed use in parking brake calipers due to independent centers of gravity and development aims, lacking an interface for parking brake mechanisms, and conventional working methods result in reduced wall thickness and limited shaping freedom.
Innovation Solution
A cold-worked brake piston with a partially deformed piston wall featuring adaptive thickness modification through strain-hardening and material redistribution, allowing for increased wall thickness in specific regions and a belt-like structure to absorb stress concentrations, along with a non-cutting production process using methods like internal roller-burnishing to achieve efficient stress distribution and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional working methods (deep drawing, ironing) are used to manufacture brake pistons, then the piston wall thickness is reduced, but the load-bearing capacity and structural integrity are compromised
Solution Approach 1:
The patent applies local plastic deformation through controlled material flow to increase wall thickness in specific regions. By changing the physical state and flow characteristics of the material during cold working, the process achieves local thickening (s2) without requiring additional material, thereby improving load-bearing capacity in critical areas while maintaining manufacturing efficiency
Solution Approach 2:
The invention creates non-uniform wall thickness distribution with locally thickened regions (s2 > s1) where stress concentrations occur. This local quality enhancement allows the piston to have adequate strength at critical locations (piston wall, interface regions) while maintaining lighter overall weight and simpler manufacturing compared to uniformly thick-walled designs
2Adaptability or versatility
If additional interface arrangements for parking brake mechanisms are added to service brake pistons, then the piston becomes multipurpose, but the structural complexity increases
Solution Approach 1:
The patent designs a universal brake piston structure with a standardized interface arrangement that can accommodate both service brake and parking brake mechanisms. The piston features a receptacle and interface geometry that allows interaction with different actuation systems (hydraulic for service brake, mechanical for parking brake), enabling one piston design to serve multiple functions without requiring completely separate components
Solution Approach 2:
The piston structure is segmented into distinct functional zones: the piston head for force application, the piston wall with localized thickening for structural integrity, and the interface arrangement for mechanism interaction. This segmentation allows each zone to be optimized independently while maintaining overall simplicity and manufacturability
3Strength
If the piston wall is locally thickened to absorb stress concentrations, then the load-bearing capacity increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs curved, radially inwardly extending wall thickenings with smooth transitions rather than sharp edges. This curvature distributes stress more evenly and is more amenable to plastic deformation processes, allowing the thickened regions to form naturally during cold working without requiring high-precision machining or multiple processing steps
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 provides a lightweight, robust brake piston with improved load-carrying capacity and streamlined production, suitable for both service and parking brake applications, with reduced material costs and minimized notch effects, while maintaining self-centering characteristics and fatigue resistance.
Implementation Method 1
adaptively modified by plastic material deformation by means of material redistribution (flow) including strain-hardening
Implementation Method 2
material redistribution (flow) including strain-hardening in its wall thickness
Implementation Method 3
cold-worked brake piston
Implementation Method 4
material redistribution (flow) including strain-hardening
Implementation Method 5
non-cutting production process using methods like internal roller-burnishing
Data Source
AI summary
The invention relates to a brake piston 1 for a brake caliper 9 of a disk brake, which is produced using working processes from a metallic material, in particular from a flat metal sheet, and is formed in one piece as a unilaterally open pot with a piston longitudinal axis A, with a piston wall 2 and with a piston head 3. There is a need for robust and light as well as alternatively constructed, efficiently producible and well guided brake pistons. The object is achieved firstly in principle on the basis of a cup-shapedly worked brake piston blank 19, in that at least one locally defined, i.e. partially cold-upset or partially ironed, cylindrical piston wall portion is present with a partially deformed piston wall 2 which is configured in adaptively modified manner by plastic material deformation by means of material redistribution (flow) including strain-hardening of its piston wall thickness of sl−x.