Chuck Elastic Stop Pawl Prevents Jaw Jamming
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Solution Overview
Problem
Chucks used for clamping rotating tools face excessive friction and jamming issues due to the interaction between the thread terminal end plane of the jaws and the nut, leading to inconvenient operation and reduced tool lifetime.
Innovation Solution
A chuck with an elastic stop pawl mechanism that blocks the lateral surface of the jaws when they reach a predetermined position, preventing further rearward movement and reducing friction by utilizing elastic recovery to reset the pawl and minimize contact between the thread terminal end plane and the nut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the nut is rotated in the loosening direction to allow the jaws to retreat into the body, then the jaws can be released from the tool, but the terminal end plane of the jaw threads rubs against the thread end of the nut causing excessive friction and jamming
Solution Approach 1:
The stop pawl is positioned in advance to contact the lateral side of the jaw before the terminal end plane of the jaw threads contacts the thread end of the nut. This preliminary action prevents the jaws from over-retreating and eliminates the harmful friction and jamming that would occur between the thread end planes.
Solution Approach 2:
The stop pawl acts as an intermediary element between the jaw and the nut. Instead of allowing direct contact between the terminal end plane of the jaw threads and the thread end of the nut (which causes friction), the stop pawl mediates by contacting the lateral side of the jaw first and preventing further rearward movement.
2Strength
If the nut is rotated in the tightening direction to tighten the tool, then the jaws clamp the tool securely, but excessive friction from previous contact must be overcome making operation inconvenient
Solution Approach 1:
The stop pawl performs a preliminary stopping action during the loosening phase, preventing the jaw terminal end plane from contacting the nut thread end. This eliminates the buildup of excessive friction before tightening, making the subsequent tightening operation smoother and more convenient while maintaining secure clamping force.
3Device complexity
If the jaws are allowed to rotate freely relative to the nut, then the mechanism is simple, but the friction between the thread end planes increases wear and reduces usage lifetime
Solution Approach 1:
The stop pawl is positioned in advance to prevent the harmful contact between the jaw terminal end plane and the nut thread end before it occurs. This simple preliminary action reduces wear on the thread surfaces and extends the usage lifetime of the chuck without significantly increasing device complexity.
4Object-affected harmful factors
If a stopping mechanism is added to prevent excessive friction, then friction and wear are reduced, but the device complexity increases
Solution Approach 1:
The stopping mechanism applies a localized function only where needed - the stop pawl contacts only the lateral side of the jaw at a specific position to prevent over-retraction. This localized intervention effectively reduces friction and wear without requiring a complex mechanism throughout the entire chuck assembly.
Solution Approach 2:
The stop pawl performs a simple preliminary stopping action that prevents the harmful contact between thread end planes. This straightforward mechanism achieves the goal of reducing friction and wear without introducing excessive complexity into the overall device.
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 elastic stop pawl mechanism effectively prevents excessive friction and jamming, ensuring reliable jaw stopping and reducing wear, thus enhancing the operational convenience and longevity of the chuck.
Implementation Method 1
A chuck with an elastic stop pawl mechanism that blocks the lateral surface of the jaws when they reach a predetermined position, preventing further rearward movement and reducing friction by utilizing elastic recovery to reset the pawl
Data Source
AI summary
A chuck is provided for use with a manual or powered driver. The chuck has a body with angularly disposed passageways. A plurality of jaws is slidably positioned within the angularly disposed passageways. A nut is rotatably mounted about the body member and has threads defined on an inner circumference that engage jaw threads. A sleeve is in driving rotational engagement with the nut so that when the sleeve is rotated with respect to the body, the jaws are moved within the passageways. A stopping mechanism that rotates with the sleeve is provided with at least one elastic stop pawl. When the stopping mechanism rotates in a first direction that causes the gripping jaws to move to the rear of the body to a predetermined position, the stop pawl blocks the lateral surface of the gripping jaws and prevents further rotational movement of the nut.