Cable Gland Clamping Device Anti-Rotation Design
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Solution Overview
Problem
Existing cable glands fail to prevent twisting of cables and their reinforcement during tightening, and loosening of the clamping device when the union nut is loosened, leading to potential disengagement.
Innovation Solution
Incorporation of a circumferential groove with a retaining ring or O-ring in the clamping device and an undercut in the screw sleeve, providing additional axial fixation and preventing rotation, along with a non-circular cross-section for mutual anti-rotation, ensuring the clamping device remains engaged during loosening of the union nut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping device is designed with a non-circular cross-section for anti-rotation engagement, then twisting of the cable during tightening is prevented, but the device complexity increases due to manufacturing requirements
Solution Approach 1:
The non-circular cross-section is applied only locally to the first engagement area of the clamping device rather than the entire device. The second engagement area maintains a simple circular cross-section that is easy to manufacture. This localized application of complex geometry minimizes manufacturing complexity while still achieving the anti-rotation function where needed.
Solution Approach 2:
The clamping device is segmented into regions with different cross-sectional geometries. The first engagement area has a non-circular cross-section for anti-rotation, while the second engagement area has a circular cross-section for ease of manufacture and rotation during loosening. This segmentation allows the complex non-circular section to be manufactured only where functionally necessary.
2Force
If the screw sleeve and clamping device have a form-fitting connection in the direction of rotation, then higher torque against rotation is achieved, but the device complexity increases due to additional fixation measures
Solution Approach 1:
The form-fitting connection is applied only to the first engagement area of the clamping device, specifically where anti-rotation torque is needed during tightening. The second engagement area maintains a simple circular interface that does not require complex fixation features. This localized form-fitting design achieves high torque resistance without adding complexity throughout the entire device.
Solution Approach 2:
The first engagement area features an asymmetric non-circular cross-section (such as hexagonal or square) that provides inherent anti-rotation capability through its geometry. This asymmetric shape creates a form-fitting connection that resists rotational forces during tightening without requiring additional symmetric fixation structures, thereby achieving high torque resistance with minimal added complexity.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a cable fitting (1) comprising a threaded sleeve (2) that can be inserted in a wall or a pipe coupling, having an external thread and a coupling nut (3) interacting with said external thread of the threaded sleeve (2). By tightening the coupling nut (3), a clamping insert (5) can be pressed against a cable (4) to be retained, wherein the cable (4) comprises armor (7) exposed at least in places within the cable fitting (1). A clamping device (8) for clamping a part of said armor (7) is provided in the cable fitting (1), said clamping device (8) partially engaging in the inner opening of the threaded sleeve (2) in the axial direction in the use position and being directly or indirectly acted upon by the coupling nut (3) outside of the threaded sleeve (2). In order to prevent rotation of the cable (4) and/or the clamping device (8) when the coupling nut (3) is tightened, the part (8a) of the clamping device (8) engaging in the threaded sleeve (2) in the use position is positively fixed on the inner face of the threaded sleeve (2) in the direction of rotation, and has, for example, a polygonal cross-section. The end face (9) of the clamping device (8) engaging in the threaded sleeve (2) can thereby act on a second clamping insert (6).