Screw Drive Cam End Face Curvature for Clamping
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Solution Overview
Problem
Existing screw drives face challenges in securely engaging small or very small screws, particularly due to layer accumulations from coating processes that can clog the drive and impair functionality, and existing solutions do not effectively address the need for temporary mechanical clamping during handling.
Innovation Solution
The screw drive design features cams with a concave and convex surface configuration that forms a contact line along the end face, allowing for a mechanical clamping effect when used with a turning tool, which enhances torque transmission and handling, while also facilitating the removal of coating material to prevent layer accumulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional screw drive with cams is used, then torque transmission is ensured, but the screw does not temporarily adhere to the drive tool during handling
Solution Approach 1:
The end face of the cam is segmented into different functional zones: a first region with a first curvature radius for tool insertion and clamping, and a second region with a second curvature radius for torque transmission. This segmentation allows the cam to simultaneously provide mechanical clamping for handling and effective torque transmission when the tool is rotated.
2Reliability
If coating processes are applied to improve corrosion resistance, then corrosion protection is improved, but layer accumulations clog the drive and impair functionality
Solution Approach 1:
The cam end face is designed with different curvature radii in different regions: a first curvature radius in the insertion region that is smaller than a second curvature radius in the torque transmission region. This local quality variation ensures that coating material does not accumulate in the insertion region, preventing clogging while still providing corrosion protection through coating in other areas.
3Ease of operation
If the end face has a concave surface contour to improve tool insertion, then insertion is facilitated, but varying layer accumulation occurs on concave surfaces
Solution Approach 1:
The end face of the cam is designed with specific curvature radii: a first curvature radius in the insertion region that facilitates tool insertion, and a second curvature radius in the torque transmission region. By carefully selecting the first curvature radius to be smaller than the second, the design avoids excessive coating accumulation while maintaining easy tool insertion.
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
The invention relates to a screw (10) with a screw head having a drive (12), wherein the drive (12) comprises cams (14a, 14b, 14c) formed by recesses introduced into the screw head around the cams (14a, 14b, 14c), wherein each cam has two side faces (18a, 18b), which are used for transmitting rotational motion, and an end face (16a, 16b, 16c) connecting the side faces (18a, 18b), the end face (16a, 16b, 16c) having a concave surface contour on the end of the screw head facing away from the screw shank. The invention is characterized in that the end face (16a, 16b, 16c) is designed such that a virtual circular periphery (20a, 20b) around the screw axis in a plane orthogonal to the screw axis and having a radius associated with the plane has a point of contact (22a, 22b, 22c) on the cam with the end face (16a, 16b, 16c). Over at least one portion of the axial height of the end face (16a, 16b, 16c) – the contact region – a plurality of such points of contact (22a, 22b, 22c) are formed, said points of contact (22a, 22b, 22c) forming a contact line (24a, 24b, 24c) in the centre of the end face (16a, 16b, 16c).