Retaining Cam With Three-Start Self-Tapping Thread for Easy Alignment
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Solution Overview
Problem
Existing quick-release systems face challenges in reducing processing effort for mounting retaining cams, especially in non-metallic components, and require complex manufacturing processes for large-scale production, with difficulties in aligning and installing larger diameter retaining cams due to single-start threads.
Innovation Solution
A retaining cam with a self-tapping three-start external thread and lateral flattened areas, allowing direct screwing into softer materials without pre-existing internal threads, and featuring a design that facilitates easy demolding and improved centering, reducing screwing torque and tilting issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-start external thread is used for the retaining cam, then the thread can be manufactured with standard processes, but the retaining cam becomes difficult to align and install, especially for larger diameters
Solution Approach 1:
The thread is segmented into three separate starting points around the circumference, creating a three-start thread. This segmentation allows multiple engagement points that guide the retaining cam into proper alignment during installation, eliminating the wobbling motion associated with single-start threads while remaining manufacturable with standard thread cutting processes.
Solution Approach 2:
The solution moves from a single linear thread start to a multi-dimensional arrangement with three starting points distributed around the circumference at 120° intervals. This dimensional change in thread configuration provides inherent alignment guidance during installation while maintaining manufacturability.
2Productivity
If a self-tapping external thread is used to screw directly into softer materials, then the assembly process is simplified by eliminating pre-threading, but the screwing-in torque increases and alignment becomes difficult
Solution Approach 1:
The self-tapping thread is segmented into three starting points around the circumference. This segmentation distributes the cutting action across three engagement points, providing inherent alignment guidance during the self-tapping process. The multiple starting points prevent the wobbling motion that occurs with single-start self-tapping threads, reducing the required screwing-in torque while maintaining the simplified assembly process.
Solution Approach 2:
The thread features localized flat areas at the three starting points around the circumference. These local modifications create engagement points that guide alignment during self-tapping installation, while the rest of the thread maintains its self-tapping cutting geometry. This local quality change enables both simplified assembly and improved alignment.
3Ease of manufacture
If lateral flattened areas are added to the base body for demolding, then injection molding becomes feasible for economical production, but the cylindrical symmetry of the base body is reduced
Solution Approach 1:
The base body is segmented by removing three cylindrical segments around the circumference, creating three lateral flattened areas. This segmentation provides the demolding features necessary for injection molding while maintaining functional symmetry through the 120° spacing of the flats. The segmentation approach enables complex manufacturing while preserving adequate geometric symmetry for the application.
Solution Approach 2:
The solution intentionally introduces asymmetry by removing cylindrical segments to create flat areas. This controlled asymmetry is necessary for injection molding demolding while the 120° spacing maintains functional symmetry. The asymmetric flat areas provide mold release surfaces without compromising the overall functional performance of the retaining cam.
Data Source
Figure 1~4
Figure 5~9
AI summary
The invention relates to a retaining cam, in particular for a quick-release system, comprising a hollow cylindrical base body (4) which has an external thread (6) for anchoring in a bore (3) of a component (2) and an internal contour (9, 10, 11, 12; 21) for connection with a locking pin (13), and with a bearing flange (5) projecting radially from the base body (4). The base body (4) has at least two lateral flats (8) offset from each other around the circumference. The external thread (6) is a self-tapping, multi-start external thread whose starting points (7) are located outside the lateral flats (8).