Hydraulic Unit Bore Work Hardening for Brake System Efficiency
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Solution Overview
Problem
The production of hydraulic units, such as master brake cylinders, is inefficient and costly due to the need for complex machining processes and the potential for voids in the inner wall of the cavity, which can lead to increased scrap and rework, while existing methods require additional protective layers and chemically aggressive media.
Innovation Solution
The hydraulic unit features a main body with a solidified edge layer on the inner wall of the cavity, achieved through forming processes like burnishing, which enhances surface quality, reduces tolerances, and eliminates machining marks, thereby improving durability and reducing the need for additional protective layers or chemical media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex machining processes (drilling, reaming, honing) are used to produce the cavity, then the bore section achieves the target diameter with proper surface quality, but the production effort and costs increase significantly
Solution Approach 1:
The cavity is pre-drilled with a smaller diameter before the final forming process. This preliminary action creates a starting geometry that guides the subsequent forming operation, allowing the material to be shaped into the final bore section geometry with proper diameter and surface quality in a single forming pass rather than multiple machining operations
Solution Approach 2:
Traditional mechanical machining processes (reaming, honing) that remove material are replaced with a forming process that shapes the material in place. The forming process uses controlled plastic deformation to achieve the target diameter and surface quality without the need for multiple cutting passes and intermediate cleanings
2Manufacturing precision
If multiple machining and cleaning steps are performed, then the bore section achieves the required surface quality, but the number of process steps and associated costs increase
Solution Approach 1:
Multiple separate operations (drilling, reaming, honing, and cleaning) are merged into a single integrated forming process. The forming operation simultaneously achieves the target diameter, proper surface quality, and eliminates the need for intermediate cleaning steps by shaping the material rather than removing it through multiple passes
Solution Approach 2:
The complex multi-step machining sequence and associated cleaning operations are extracted and replaced with a single forming process. This extraction eliminates unnecessary process steps while maintaining the required surface quality through the material shaping mechanism inherent in the forming process
3Ease of manufacture
If the cavity is cast with aluminum alloy, then the main body achieves good casting properties, but voids form in the inner wall requiring additional inspection and potentially increasing scrap
Solution Approach 1:
The cavity is pre-formed during casting with a geometry that anticipates the subsequent forming operation. This preliminary shaping during casting allows the material to be compacted and voids to be eliminated during the forming process, ensuring reliability while maintaining the ease of casting the main body
Solution Approach 2:
The material parameters (density, microstructure) are changed through the forming process to eliminate voids. The forming operation applies controlled pressure and deformation that compacts the cast material, closing voids and creating a dense, reliable bore section while preserving the benefits of aluminum alloy casting
4Strength
If a separate protective layer is applied to the cavity, then wear resistance is improved, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The forming process creates localized material properties in the bore section with enhanced density and strength. This local quality change provides the necessary wear resistance directly in the critical bore section area without requiring a separate protective layer, simplifying the manufacturing process
Solution Approach 2:
The material itself provides the protective function through the forming process. The controlled plastic deformation during forming creates a hardened, dense surface layer that serves as its own protective coating, eliminating the need for external protective layers and reducing manufacturing complexity
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 results in improved wear resistance, reduced friction, and optimized piston guidance, leading to lower production costs and reduced rejects, with enhanced sliding behavior and sealing performance without the need for additional protective layers or chemical treatments.
Implementation Method 1
the material structure in an edge layer of an inner wall of the cavity in the bore section has been solidified by forming
Implementation Method 2
The material structure in an area close to the surface is also homogenized and compacted
Data Source
Figure 1~3
AI summary
The invention relates to a hydraulic unit (1) for producing brake pressure for a hydraulic motor-vehicle brake system, comprising a main body (2), a cavity (3), which is arranged in the main body (2) and which has at least one first bore segment (4) having a defined target diameter (Ds), in which a cylindrical piston (5) movable in the axial direction is arranged, which, in the cavity (3), bounds at least one pressure chamber (6), which is filled with a hydraulic fluid, for producing brake pressure in a brake circuit (7), and at least a first and a second sealing element (8, 9) for sealing the cylindrical piston (5), which sealing elements are arranged at an axial distance from each other. According to the invention, in order to provide a hydraulic unit (1) of the type in question that can be produced more effectively and economically while the technical requirements nevertheless remain fulfilled, the material of the main body (2) in a surface layer (10) of an inner wall (11) of the cavity (3) in the bore segment (4) has a material microstructure that is work-hardened.