CV Joint Track Groove Profile for Stable Ball Contact
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Solution Overview
Problem
The existing constant velocity universal joints face challenges in maintaining a stable contact state between track grooves and balls, leading to variations in durability due to differences in track groove shapes formed by different processing methods, which complicates quality control and increases manufacturing costs.
Innovation Solution
The constant velocity universal joints are designed with track grooves formed into an elliptical shape near the spherical surface and a Gothic arch shape for management, with continuous angles between these shapes gradually reduced from the joint opening side to the deep side, allowing for stable contact and reduced vertical clearance, facilitating quality control and omitting costly machining processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cold-forging finishing is used to form track grooves, then manufacturing cost is reduced and productivity is improved, but the track grooves are formed into a Gothic arch shape which causes unstable contact between balls and track grooves
Solution Approach 1:
The track groove cross-section is designed with non-uniform curvature: the curvature radius at the bottom is smaller than at the opening, creating different local geometries. This local variation in shape allows the groove to provide stable angular contact (similar to elliptical grooves) while being manufacturable by cold-forging (Gothic arch-like overall form), thus resolving the contradiction between manufacturing efficiency and contact stability.
Solution Approach 2:
The invention changes the geometric parameters of the track groove by specifying that the curvature radius at the bottom (R1) is smaller than the curvature radius at the opening (R2). This parameter variation creates the desired contact characteristics while maintaining compatibility with cold-forging processes, improving both reliability and productivity.
2Reliability
If traditional finishing processes (grinding, quenched-steel cutting) are used, then the track grooves are formed into an elliptical shape that stabilizes contact, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The invention replaces expensive, time-consuming traditional finishing processes (grinding, quenched-steel cutting) with a more economical cold-forging process. By designing the track groove geometry to achieve stable contact through curvature radius variation rather than through precise elliptical shaping, the patent eliminates the need for costly secondary operations while maintaining contact stability.
Solution Approach 2:
The invention extracts the essential functional requirement (stable contact) from the traditional elliptical groove design and achieves it through a different geometric approach (curvature radius variation in cold-forged Gothic arch shape), thereby eliminating the need for traditional finishing processes.
3Productivity
If track grooves are formed by cold-forging only, then machining processes can be omitted and yield increases, but quality control becomes more difficult due to shape variations
Solution Approach 1:
The invention establishes specific parameter relationships (R1 < R2, and both greater than a threshold value) that define the track groove geometry. These parameter specifications provide clear quality control criteria for cold-forging processes, making shape control more objective and measurable while maintaining high material yield.
Solution Approach 2:
The invention replaces complex multi-step mechanical finishing processes with a streamlined cold-forging process controlled by defined geometric parameters. This substitution simplifies the manufacturing system while maintaining precision through parameter-based quality control rather than process-based control.
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 design stabilizes the contact state between balls and track grooves, enhances durability, and reduces manufacturing costs by eliminating the need for additional machining processes, while maintaining sufficient vertical clearance for shape management.
Implementation Method 1
at least one of or both the track grooves of the outer joint member and the track grooves of the inner joint member are formed by cold-forging finishing
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
Provided is a constant velocity universal joint having track shapes which facilitate quality control on a forging die set and products as in a conventional case while securing higher durability through securement of a stable contact state of forging-molded tracks and finishing-processed tracks with respect to balls. At least one of each of track grooves (22) of an outer joint member (23) and each of track grooves (25) of an inner joint member (26) is formed by cold-forging finishing. A track groove bottom side of the at least one of each of the track grooves (22) and the track grooves (25) is formed into a Gothic arch shape in horizontal cross-section, and track groove opening sides of the at least one of each of the track grooves (22) and the track grooves (25) are each formed into an elliptical shape in horizontal cross-section.