Clamping Device Motion Conversion for Handheld Tool Retention
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Solution Overview
Problem
Handheld power tool clamping devices face issues with the clamping force being reduced during braking operations, leading to potential detachment of tools from the spindle due to moments of inertia causing relative movement between the tool and the clamping unit.
Innovation Solution
A hand-held power tool clamping device with a movement-changing unit, specifically a lifting unit, that converts rotational movement into axial movement to maintain or increase clamping force by interacting with ramp-shaped lifting elements, and a cam mechanism with control elements and recesses to limit angular range and ensure secure coupling, preventing the tool from running off the spindle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping unit is secured to the spindle by a thread connection, then the tool can be firmly clamped during normal operation, but during braking operation the moment of inertia causes relative movement that reduces the clamping force and may allow slippage
Solution Approach 1:
The lifting unit is designed to counteract the harmful effect of moment of inertia before it can cause tool slippage. During braking operation, when the tool tends to move axially away from the spindle due to inertia, the lifting unit automatically generates an opposing axial force through the interaction of ramp-shaped lifting elements, preventing the reduction of clamping force and maintaining reliable tool retention.
Solution Approach 2:
The clamping device transitions from a static thread connection to a dynamic system that automatically adjusts during braking. The lifting unit with ramp-shaped elements converts the relative rotational movement between tool and clamping unit during braking into beneficial axial movement that maintains or increases clamping force, adapting the clamping action to the dynamic conditions of braking operation.
2Reliability
If the lifting elements have a steep slope to generate sufficient axial stroke, then the clamping force is maintained during braking, but the pitch of the lifting elements must be greater than the thread pitch which increases the complexity of the mechanism
Solution Approach 1:
The lifting unit combines multiple functional elements into a compact integrated mechanism. The ramp-shaped lifting elements are formed integrally with the clamping unit components, merging the lifting function with the existing clamping structure. This integration reduces the number of separate parts and simplifies the overall mechanism while maintaining the necessary axial stroke generation capability during braking operation.
3Ease of manufacture
If the lifting elements are formed integrally with the clamping elements, then the number of parts is reduced and assembly is simplified, but the manufacturing complexity of each component increases
Solution Approach 1:
The lifting unit is segmented into distinct functional zones within the integrally formed components. The ramp-shaped lifting elements are designed as specific geometric features on the clamping unit components, allowing the complex lifting function to be distributed across different surfaces and features of the integrated parts. This segmentation approach enables modular manufacturing of complex components while maintaining assembly simplicity.
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
Effectively maintains or increases clamping force during braking operations, preventing the tool from detaching from the spindle by generating axial stroke and limiting rotational movement, thus ensuring secure tool retention.
Implementation Method 1
The lifting unit has lifting elements, in particular ramp-shaped lifting elements, by means of which, as a result of the first relative movement, the second relative movement is generated
Data Source
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AI summary
The invention relates to a chucking device for a hand machine tool having at least one chucking unit (12a; 12b; 12c) for chucking a tool (14a; 14b; 14c) on a spindle (16a; 16b; 16c), and having at least one runoff safety unit (18a; 18b; 18c) for preventing the chucking unit (12a; 12b; 12c) and/or the tool (14a; 14b; 14c) from running off of the spindle (16a; 16b; 16c). According to the invention, the runoff safety unit (18a; 18b; 18c) comprises at least one motion change unit (20a; 20b; 20c) for at least partially transferring a first relative motion between at least two chucking elements (22a, 24a; 22b, 24b; 22c, 24c) of the chucking unit (12a; 12b; 12c) into a second relative motion.