Keyless Chuck Locking Device for Reverse Rotation Jaw Loosening
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Solution Overview
Problem
Keyless chucks used in machines or motor-driven power tools with reversible rotation direction risk jaw loosening when driven in reverse rotation, leading to unintended release of tools, and existing solutions do not effectively prevent this issue across all rotation directions.
Innovation Solution
A chuck with a locking device featuring a ratchet mechanism operated by a locking control sleeve, cooperating with a cam and elastic element, which blocks loosening rotation while allowing tightening rotation, ensuring the jaws remain gripped in both rotation directions by using a toothed ring, ratchet ring, and locking ring with asymmetrical teeth and interlocking elastic tabs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a keyless chuck uses a simple fitting mechanism without locking device, then the device complexity is reduced and ease of operation is improved, but the reliability deteriorates because jaws will loosen when driven in reverse rotation
Solution Approach 1:
The ratchet teeth are designed with an asymmetrical profile where one side is inclined and the other side is perpendicular or substantially perpendicular to the rotational direction. This asymmetry allows the teeth to engage smoothly in the tightening direction while blocking movement in the loosening direction, providing automatic locking without complex additional components
Solution Approach 2:
The ratchet mechanism automatically locks the jaws in the tightening position through the engagement of ratchet teeth with the toothed ring, eliminating the need for manual locking operations. The elastic element automatically pushes the ratchet ring to maintain engagement, providing self-sustaining locking functionality
2Reliability
If a locking device with ratchet mechanism is added to prevent jaw loosening, then the reliability is improved, but the device complexity increases due to additional components like toothed ring, ratchet ring, and elastic element
Solution Approach 1:
The locking function is merged with the existing fitting mechanism by integrating the ratchet ring into the outer casing and the toothed ring into the base body. The elastic element is integrated within the ratchet ring structure, combining multiple functions into unified components rather than adding separate independent locking mechanisms
Solution Approach 2:
The ratchet mechanism serves multiple functions: it prevents jaw loosening in reverse rotation, maintains gripping force during operation, and allows easy manual release when needed. The same structural components fulfill both the fitting and locking functions, providing multi-functionality without requiring separate dedicated locking systems
3Ease of operation
If the ratchet teeth have asymmetrical profile to allow tightening rotation, then the ease of operation is improved for manual locking, but the manufacturing precision requirements increase due to the complex tooth geometry
Solution Approach 1:
The asymmetrical tooth profile concentrates the precision requirements to specific critical areas: the inclined face angle and the perpendicular locking face. The majority of the tooth structure can be manufactured with standard tolerances, while only the engagement surfaces require precise geometry to ensure proper ratchet action and locking force
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 locking device securely holds tools in place during both clockwise and counterclockwise rotations, preventing slipping and allowing easy manual loosening, compatible with various fitting mechanisms, including self-tightening, key-based, and hybrid types.
Implementation Method 1
an elastic element arranged under compression between the ratchet ring and the toothed ring, so that the elastic element permanently pushes the ratchet ring towards the axial locking position
Implementation Method 2
a cam determining axial movement of the ratchet ring towards the axial unlocking position when the locking control sleeve is rotated between the angular locking and release positions
Implementation Method 3
the ratchet mechanism blocks relative rotation between the base body and the outer casing in a loosening direction for loosening the grip of the jaws but allows relative rotation in a tightening direction for tightening the grip of the jaws
Data Source
AI summary
The chuck with locking device has a ratchet mechanism comprising a toothed ring with engagement teeth fixed to one of an outer casing and a base body. A ratchet pawl is coupled to the toothed ring when a locking control sleeve is in a locking position and the locking pawl is separated from the tooth ring when the locking control sleeve is in a release position. A release elastic element is arranged under compression between the outer casing and a locking ring. The locking ring is fixed inside a locking control sleeve. A cam groove is formed in the locking ring. A pin is inserted in the cam groove and in a hole formed in the base body. The locking control sleeve moves the locking ring between the locking and unlocking positions.