Fine Blanking of Friction Plates Without Damaging Friction Layers
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Solution Overview
Problem
Existing fine blanking techniques for forming friction plates face challenges in achieving precise, high-fatigue resistance and surface quality due to shear deformation and surface roughness during the blanking process, which affects the mechanical properties and service life of the friction plates.
Innovation Solution
A fine blanking method and device that uses a buffer mechanism with ring grooves and a buffer layer to transform vertical pressure into flexible pressure, ensuring tight fixation and protection of friction material layers, while applying three-dimensional compressive stress to achieve a shear fractural surface with controlled strain and interlamellar bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strong three-dimensional compressive pressure is applied by blank holders to tightly fix the base sheet, then the base sheet is tightly fixed and forming precision is improved, but the friction material layers may be damaged or deformed
Solution Approach 1:
The blank holder pressing surface is segmented into different regions: a first pressing surface that contacts the base sheet and applies strong compressive pressure for tight fixation, and a second pressing surface that contacts the friction material layers and applies gentle pressure to avoid damage. This segmentation allows different parts of the blank holder to perform different functions simultaneously.
Solution Approach 2:
The blank holder is designed with non-uniform pressing surfaces having different properties in different locations. The first pressing surface has properties suitable for strong compression (e.g., harder, more rigid), while the second pressing surface has properties suitable for gentle contact (e.g., softer, more compliant). This local quality differentiation resolves the contradiction between needing strong pressure for precision and gentle pressure for protection.
2Shape
If absolute shear deformation is applied near the blanking sections during the blanking process, then a blanked surface with continuous and compact streamline is obtained, but surface roughness increases and microcracks may form
Solution Approach 1:
The blank holders apply pre-compression to the base sheet before the actual blanking cutting action occurs. This preliminary compression prepares the material structure, reducing surface roughness and preventing microcrack formation during the subsequent shear deformation, while still allowing the continuous streamline to form.
Solution Approach 2:
The process parameters are optimized by controlling the magnitude and distribution of compressive pressure applied by the blank holders. By adjusting these parameters, the material undergoes controlled shear deformation that produces continuous streamlines while minimizing surface roughness and microcrack formation.
3Strength
If residual compressive stress is generated near the blanking sections to promote mechanical properties, then fatigue resistance is improved, but the friction material layers may experience excessive stress and degrade
Solution Approach 1:
The stress distribution is segmented through the multi-surface blank holder design, which concentrates the compressive stress primarily in the base sheet while shielding the friction material layers from excessive stress. This allows residual compressive stress to be generated in the base sheet for improved fatigue resistance without degrading the friction material layers.
Solution Approach 2:
The first pressing surface acts as an intermediary that transmits compressive force to the base sheet while the second pressing surface protects the friction material layers. This intermediary structure allows the generation of beneficial residual compressive stress in the base sheet without subjecting the friction material layers to harmful stress levels.
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 method and device result in friction plates with a continuous, compact sectional streamline, surface roughness of not more than 1.6 μm, residual compressive stress of not less than 270 MPa, and controlled strain within 0.01, enhancing mechanical properties and preventing microcracks, thus improving the service life.
Implementation Method 1
the buffer layer is made of an elastic material
Data Source
AI summary
A fine blanking device and method for forming a friction plate with friction material layers. The fine blanking device includes an upper die, a lower die, a guide mechanism, a punch and a counter punch. Upper and lower blank holders are respectively provided at outer circumferences of the punch and the counter punch. The upper and lower blank holders are respectively provided with a buffer mechanism. Friction material powders are sintered on both sides of the base sheet. The friction material layers are trimmed and planished by hot pressing. The base sheet with the friction material layers is fixed by the upper blank holder and the lower blank holder. A tooth profile with an absolute shear fractural surface is formed. The fixing indentation of the V-shaped structure of the friction material layers is cut off for obtaining a finished friction plate product with the friction material layers.