Power Tool Clamping Hub Prevents Loosening
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Solution Overview
Problem
Existing devices for fastening tool members on rotating output shafts of power tools often experience loosening or over-tightening issues due to torque transmission, particularly when the rider plate contacts the ground, limiting secure fastening in both rotational directions.
Innovation Solution
A device featuring a connecting hub that secures the rider plate, allowing it to rotate relative to the hub without applying clamping force, and a clamping element that applies force on a support surface of the hub, ensuring the tool member is fixed regardless of rotational direction, with a captive securing mechanism to prevent loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the clamping nut is immediately contacting the fastening rim of the rider plate, then the clamping force is transmitted effectively, but torque acts on the clamping nut causing loosening or over-tightening
Solution Approach 1:
The invention introduces an intermediary component (the rider plate with fastening rim) between the clamping nut and the tool member. The clamping nut clamps the rider plate, which in turn clamps the tool member via the fastening rim against the pressure plate. This intermediary structure allows the clamping force to be transmitted effectively while preventing direct torque transmission to the clamping nut, thus preventing loosening or over-tightening.
2Reliability
If a left-hand thread is provided for clockwise rotating drive shafts, then loosening is prevented in one rotational direction, but securing action is lost in the opposite rotational direction
Solution Approach 1:
The invention employs asymmetric geometry in the form of a conical surface on the rider plate that interfaces with a corresponding conical surface on the tool member. This asymmetric conical interface provides directional securing action that works effectively in both rotational directions, eliminating the need for thread direction changes while maintaining reliability across different rotation directions.
3Reliability
If the clamping device is tightened excessively to prevent loosening, then security is improved, but release becomes difficult and overload occurs
Solution Approach 1:
The invention incorporates a spring element that provides dynamic, elastic deformation capability to the clamping mechanism. The spring allows the clamping device to accommodate torque fluctuations and ground contact forces through elastic deformation, maintaining secure fastening without requiring excessive tightening force. This dynamic behavior enables easy release while preventing loosening during operation.
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
The solution effectively prevents loosening of the clamping device and ensures secure fastening of the tool member across all rotational directions, reducing the risk of over-tightening and overload, while simplifying installation and preventing component misalignment.
Implementation Method 1
the rider plate is rotatable relative to the connecting hub without providing a clamping force and/or, in final mounted position, i.e., after overcoming a friction force, is rotatable relative to the connecting hub
Implementation Method 2
The clamping device that is mounted on the output shaft, preferably a clamping nut or a clamping screw, exerts by means of the clamping element a clamping force on the tool member
Data Source
AI summary
A device for fastening a tool member on an output shaft of a power tool has a support plate supporting the tool member and a clamping element embodied as a connecting hub. The connecting hub is penetrated by the output shaft and is rotationally fixed on the output shaft. A rider plate is secured on the connecting hub and rotatable relative to the connecting hub. Support plate, tool member, rider plate, and connecting hub are arranged such that the output shaft projects through support plate, tool member, rider plate, and connecting hub. A clamping device is carried on an end of the output shaft. The clamping device acts on a support surface of the connecting hub and fixes through the connecting hub the tool member on the support plate. Connecting hub, rider plate, and pressure plate together form preferably a conjoint, connected component assembly.