Keyless Chuck Sleeve Biasing to Prevent Inertial Locking
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Solution Overview
Problem
Keyless chucks on power drivers can 'lock' during drilling operations due to inertial forces, leading to incremental tightening or loosening of tool shanks, making them difficult to open by hand.
Innovation Solution
A biasing element is introduced between the sleeve and nut to bias the sleeve toward a neutral position, limiting the inertial force transferred to the nut, and a gap is provided to absorb this force before engagement, preventing 'locking' or loosening, which can be implemented using a spring, rubber cushion, or inner race of a bearing assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chuck operates without a biasing element, then the structure is simpler, but the inertial forces cause the chuck to lock or loosen incrementally during operation
Solution Approach 1:
A biasing element is introduced as an intermediary component between the drive shaft and the chuck mechanism. This biasing element absorbs and limits the inertial forces generated during drilling operations, preventing these forces from causing the chuck to lock or loosen incrementally. The biasing element acts as a mediator that protects the chuck system from harmful dynamic loads while maintaining the overall structural simplicity.
Solution Approach 2:
The biasing element provides beforehand cushioning by being pre-configured to absorb inertial forces before they can cause damage to the chuck system. During normal operation, the biasing element is already in place to cushion against the sudden deceleration and inertial forces that occur during drilling, preventing the chuck from locking or loosening before these forces can cause problems.
2Ease of operation
If the sleeve is directly engaged with the nut, then the force transmission is more direct, but the inertial force causes locking or loosening of the tool shank
Solution Approach 1:
The biasing element serves as an intermediary between the sleeve and the nut, modifying the force transmission path. Instead of direct engagement where inertial forces would directly cause locking or loosening, the biasing element is inserted into the force transmission path to limit and control the forces transferred to the nut, thereby maintaining tool shank security while preserving manual adjustability.
Solution Approach 2:
The biasing element provides preliminary anti-action by being pre-configured to counteract the harmful inertial forces before they can cause locking or loosening of the tool shank. The biasing element is already in place to oppose and limit the inertial forces generated during operation, preventing the sleeve from transmitting excessive forces to the nut that would cause the tool shank to lock or loosen.
3Reliability
If no gap is provided between components, then the structure is more compact, but the inertial force cannot be absorbed, leading to chuck locking
Solution Approach 1:
A gap is provided in the force transmission path between the sleeve and the nut, and the biasing element is positioned within this gap to absorb inertial forces. This gap allows the biasing element to function as a cushion, absorbing the sudden inertial forces during drilling operations. The gap is strategically designed to be minimal, maintaining a compact chuck structure while providing sufficient space for the biasing element to perform its force-absorbing function.
Solution Approach 2:
The design changes the physical parameters of the force transmission path by introducing a controlled gap and positioning the biasing element within it. This parameter change allows the system to absorb inertial forces through the gap and biasing element mechanism, ensuring smooth chuck operation during drilling while keeping the overall chuck volume minimal through optimized gap dimensions.
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 solution prevents the chuck from locking or inadvertently loosening, allowing for smooth operation and easy manual adjustment of the tool shank, enhancing user control and reducing wear on the chuck components.
Implementation Method 1
The biasing element limits an inertial force of the sleeve applied to the nut during operation of the powered driver
Data Source
AI summary
A chuck is provided for use with a powered driver having a rotatable drive shaft. The chuck includes a plurality of jaws (22) movably disposed in passageways (40) of a cylindrical body (14), a nut (16) rotatably mounted about the body (14) and in communication with the jaws (22) such that rotation of the nut (16) in a closing direction moves the jaws (22) toward each other and rotation of the nut (16) in an opening direction moves the jaws (22) away from each other, and a sleeve rotatably mounted about the body (14). The sleeve is in communication with the nut (16) such that rotation of the sleeve rotationally drives the nut (16). The chuck also including a biasing element (208) disposed between the nut (16) an at least a portion of the sleeve configured to bias the sleeve toward a neutral position. The biasing element (208) limits an inertial force of the sleeve applied to the nut during operation of the powered driver.