Hub Unit Caulking via Linear Pressing Die
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Solution Overview
Problem
Conventional driving-wheel supporting hub units face increased manufacturing costs due to the need for large apparatuses to form caulking portions, and issues with heat generation during forging that can degrade lubricating grease and inner ring strength.
Innovation Solution
The caulking portion is formed using a pressing die that does not rock with respect to the hub, under cold working conditions, eliminating the need for a mechanism to prevent swaying and reducing the risk of heat transfer, thereby minimizing apparatus size and maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an orbital forging press is used to form the caulking portion by plastically deforming the cylindrical portion, then the caulking portion can be formed to hold the stepped surface, but the apparatus becomes huge and manufacturing cost increases
Solution Approach 1:
Instead of using a conventional orbital forging press that rocks the pressing die, the invention inverts the approach by using a pressing die that moves in a straight line along the axial direction. This inversion of the pressing mechanism eliminates the need for complex rocking mechanisms and support structures, thereby reducing apparatus size while still achieving the desired caulking portion formation.
Solution Approach 2:
The invention extracts and removes the unnecessary rocking mechanism and complex support structures from the conventional orbital forging press. By taking out these redundant components and replacing them with a simple linear pressing motion, the apparatus is simplified and its size is reduced while maintaining the functional capability of forming the caulking portion.
2Productivity
If hot forging is used to form the caulking portion, then the forming process can be completed, but heat is generated that degrades lubricating grease and distorts the inner end surface of the inner ring
Solution Approach 1:
The invention changes the temperature parameter from hot forging to cold working conditions. By performing the plastic deformation of the cylindrical portion at ambient or lower temperatures rather than elevated temperatures, the harmful heat generation is eliminated. This prevents degradation of lubricating grease and distortion of the inner end surface of the inner ring while still achieving complete caulking portion formation.
3Ease of manufacture
If the pressing die rocks with respect to the hub during caulking portion formation, then the caulking portion can be formed, but a mechanism to prevent swaying must be incorporated into the apparatus
Solution Approach 1:
The invention inverts the conventional approach by eliminating the rocking motion of the pressing die and using instead a linear axial motion. This inversion removes the need for swaying prevention mechanisms entirely, as the linear motion inherently prevents lateral instability and eliminates the complexity of support structures required to constrain rocking movements.
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 reduces manufacturing costs and prevents heat-related issues such as grease deterioration and inner ring distortion, ensuring improved strength and longevity of the driving-wheel supporting hub unit.
Implementation Method 1
the cylindrical portion is plastically deformed simultaneously over its whole periphery and axially outward along the working surface
Implementation Method 2
under temperature conditions of cold working
Data Source
AI summary
When an inner ring of a driving-wheel supporting hub unit is fixed to a hub, a pressing die is displaced downward and an annular working surface at a lower end surface of the pressing die is pressed against a front end of a cylindrical portion over its whole periphery. Further, in this state, the pressing die is pressed downward toward the hub without rocking the pressing die relative to the hub. Thus, the cylindrical portion is plastically deformed radially outward along the working surface simultaneously over its whole periphery. By adopting this method, the operation of plastically deforming the cylindrical portion at the inner end of the hub to form a caulking portion, can be easily and performed accurately. Accordingly, the structure of the caulking portion forming apparatus can be simplified.