Friction Disc Hole Fabrication via Punching and Machining
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Solution Overview
Problem
The conventional manufacturing process for friction members, such as clutch friction discs, is complex and costly, especially when dealing with metal supports made of hardened steel, as it involves difficult drilling operations that lead to premature wear of drills.
Innovation Solution
The method involves punching first holes of a constant diameter through the friction lining and support, and then punching and machining second holes to widen their diameter, using a flat-bottomed drill, eliminating the need for countersinking tools and reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional drilling operations are used on hardened steel supports, then holes can be formed through the material, but the process becomes complex and costly with premature drill wear
Solution Approach 1:
The invention changes the approach from conventional drilling to a two-stage process: first punching to create initial holes, then selective machining only of the lining material. This parameter change in the manufacturing process eliminates the need for difficult drilling operations on hardened steel, reducing process complexity and tool wear while maintaining the required hole geometry for rivet insertion
Solution Approach 2:
The hole formation process is segmented into two distinct operations: punching to create the initial hole through both lining and support, followed by selective machining only of the lining material to the final diameter. This segmentation allows each operation to be optimized independently, avoiding the complexity of single-step drilling through hardened material
2Manufacturing precision
If countersinking cutting tools are used to form counterbores through lining and support, then the required hole geometry is achieved, but the manufacturing process becomes more complex and expensive
Solution Approach 1:
The invention extracts the machining operation from the support material, applying it only to the lining material after punching. By taking out the machining step from the hardened steel support and applying it only to the softer lining, the required hole geometry is achieved with simpler tools and reduced process complexity
Solution Approach 2:
Instead of machining through both lining and support as in conventional counterboring, the invention inverts the approach by punching through both materials first, then machining only the lining. This inversion simplifies the tooling requirements while maintaining the necessary hole geometry for proper rivet seating
3Productivity
If drilling operations are performed on high hardness materials, then holes can be formed, but the drills wear out prematurely increasing production costs
Solution Approach 1:
The invention changes the material engagement parameters by using punching instead of drilling for the initial hole formation through hardened steel. Punching operations on high hardness materials are significantly easier and cause minimal tool wear, thereby maintaining high productivity while extending tool life
Solution Approach 2:
The punching tool used to create initial holes through the hardened support is a simple, inexpensive tool that can be easily replaced if needed, unlike expensive precision drills that wear out prematurely. This approach prioritizes tool simplicity and low cost over tool longevity, as the punching operation itself causes minimal wear
Data Source
Figure 1
Figure 2~5
AI summary
The disk (3) has a friction liner (6) fixed at a metal support (7). A set of holes (8) comprises constant diameter formed through the liner and the support. Another set of holes (9) comprises a part whose diameter crossing the liner, and another part whose diameter is lower than the former diameter, where the latter part is cut-out through the support. The diameter of the former set of holes is equal to the diameter of the latter set of holes. Friction bodies (2) are fixed on opposite faces of the disk by a rivet (12). An independent claim is also included for a friction bodies manufacturing method.