Inner Joint Part for Constant Velocity Universal Joints
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Solution Overview
Problem
Current methods for producing inner joint parts for constant velocity universal joints are inefficient and costly, particularly due to extensive machining requirements and tool wear, especially in joints with partial ball track functionality.
Innovation Solution
The inner joint part features a combination of hard-machined and unmachined ball track portions, with soft-machining before hardening and selective hard-machining after, reducing machining time and tool wear, and an asymmetric design to minimize material and weight, allowing for cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire ball track is hard-machined, then the guiding precision for torque transmitting balls is improved, but the machining time and tool wear increase significantly
Solution Approach 1:
The ball track is divided into two distinct portions: a first track portion that is hard-machined to provide precise guiding surfaces for torque transmitting balls, and a second track portion that remains unmachined. This segmentation allows the machining process to focus only on the functional guiding areas, reducing overall machining time while maintaining necessary precision where required.
Solution Approach 2:
Different portions of the ball track are given different surface qualities appropriate to their function. The first track portion receives hard-machining to achieve high guiding precision, while the second track portion remains in its as-formed state since it does not require guiding functionality. This local differentiation optimizes both precision and productivity.
2Manufacturing precision
If the entire ball track is hard-machined, then the guiding precision for torque transmitting balls is improved, but the tool wear increases due to larger cutting face
Solution Approach 1:
The ball track is segmented into a hard-machined first track portion and an unmachined second track portion. By limiting hard-machining to only the first track portion, the cutting face area is reduced, which directly decreases tool wear and extends tool life while still providing adequate guiding precision for the torque transmitting balls.
Solution Approach 2:
High machining precision is applied locally only to the first track portion where guiding function is required, rather than uniformly across the entire ball track. This localized approach minimizes the total cutting face area, reducing tool wear and extending tool life.
3Strength
If the inner joint part is designed with full material coverage for complete ball tracks, then the structural integrity is maintained, but the weight and material cost increase
Solution Approach 1:
The inner joint part employs an asymmetric design where the ball tracks are not uniformly distributed or fully formed across the entire structure. Instead, the ball tracks are concentrated in specific regions where they are needed for torque transmission, creating an asymmetric layout that reduces unnecessary material usage, weight, and cost while preserving structural integrity in the functional areas.
Data Source
AI summary
An inner joint part for a constant velocity universal joint, more particularly a constant velocity plunging joint. The inner joint part (2) includes an outer spherical guiding face (3) for guiding a ball cage (24) of the constant velocity universal joint; a plurality of circumferentially distributed ball tracks (4) formed into the spherical guiding face (3) and provided for receiving torque transmitting balls (25); wherein the ball tracks (4) each comprise a hard-machined first track portion (11) for guiding the balls (25) as well as an unmachined second track portion (12) which does not have a guiding function for the balls. A process of producing an inner joint part as well as a constant velocity universal joint with an inner joint part are also provided.