Hardened Primary Head Solid Rivet for Clutch Assembly
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Solution Overview
Problem
In restricted construction spaces, the formation of riveted joints in motor vehicle clutches is hindered by obstructing components, leading to partial contact of the rivet header with the primary head, which can result in a weakened joint, necessitating the use of more expensive blind rivets to ensure joint security.
Innovation Solution
A rivet with a primary head of greater hardness than the shank, allowing for secure joint formation even with partial contact, as the harder primary head resists deformation and prevents gaps, eliminating the need for blind rivets by maintaining joint integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard rivet with a softer primary head is used, then the rivet shank can be easily deformed to form a closing head, but the primary head bends away when the rivet header bears only partially on it, creating gaps that weaken the joint
Solution Approach 1:
The rivet is designed with non-uniform hardness distribution: the primary head has higher hardness (50-65 HRC) to resist bending under partial header contact, while the rivet shank maintains lower hardness for easy plastic deformation to form the closing head. This local differentiation of material properties resolves the contradiction between maintaining joint strength and enabling easy deformation.
Solution Approach 2:
The patent changes the physical parameter of hardness selectively in different regions of the rivet. The primary head is hardened through heat treatment or surface treatment to achieve 50-65 HRC, while the shank remains softer. This parameter change allows the primary head to maintain its position and prevent gaps even when the rivet header does not fully contact it, while the shank can still be deformed to create the closing head.
2Reliability
If a blind rivet with additional sleeve and complicated geometry is used, then the riveted joint remains secure even with partial rivet header contact, but the cost of the rivet increases considerably
Solution Approach 1:
Instead of using a complex blind rivet structure with additional sleeves, the patent achieves reliable joint security by applying local quality enhancement - hardening only the primary head region. This simpler approach maintains joint integrity under partial header contact while avoiding the additional cost and complexity of blind rivet designs.
Solution Approach 2:
The patent uses a simple solid rivet design that is cheaper than blind rivets, sacrificing the reusability or adjustability that blind rivets might offer. The rivet is designed as a single-use, disposable fastener that provides adequate performance for the application, thereby reducing cost while maintaining sufficient joint security.
3Ease of manufacture
If the primary head and rivet shank are made from the same material with uniform properties, then the manufacturing process is simpler, but the rivet header must fully contact the primary head to prevent bending and maintain joint quality
Solution Approach 1:
The patent applies local quality by creating a hardness gradient within the rivet structure. The primary head is hardened to 50-65 HRC while the shank remains softer, allowing the rivet header to make partial contact with the primary head without causing bending. This local differentiation eliminates the requirement for full header contact while maintaining joint quality.
Solution Approach 2:
The patent changes the hardness parameter selectively in the primary head region through heat treatment or surface treatment processes. This parameter change allows the primary head to resist bending under partial contact conditions while the softer shank remains amenable to deformation, thereby relaxing the operational requirement for full header contact.
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 solution enables secure and cost-effective riveting of clutch components in compact spaces without the need for blind rivets, replacing traditional screwed joints and simplifying assembly processes.
Implementation Method 1
the primary head has a greater hardness than the rivet shank. Owing to the greater hardness of the primary head in comparison with the rivet shank, a greater resistance against plastic deformation is provided by the primary head
Implementation Method 2
a rivet shank, joined to the primary head so as to constitute a single piece therewith, is plastically deformed, by means of a riveting tool, to form a closing head
Data Source
AI summary
A rivet, in particular a solid rivet, for riveting components, which has a primary head for bearing on a component to be riveted and a rivet shank, which is plastically deformable to form a closing head, joined to the primary head so as to constitute a single piece therewith. The primary head has a greater hardness than the rivet shank. Owing to the greater hardness of the primary head, the rivet joint can be produced in a reliable and cost effective manner, even in the case of a rivet header bearing only partially on the primary head.