Integrated Drawbar Clamping Chuck for Pallet Safety
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Solution Overview
Problem
Clamping devices for machine tools face challenges in maintaining high position accuracy and safety, especially when compressed air is not available, and in handling and storage due to preconnected drawbars, which can lead to side forces and potential loss of the pallet during high external forces like tool breakage.
Innovation Solution
A clamping device with an integrated drawbar that is form-lockingly mounted in the chuck, allowing rotational movement to prevent extraction during high overload and ensuring safety locking without increasing cutting force, while maintaining axial clamping force transmission and preventing side forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a preconnected drawbar is used for storage and handling, then storage capability is improved, but handling ability deteriorates
Solution Approach 1:
The drawbar is segmented into two independent parts: a fixed drawbar integrated in the chuck and a separate movable drawbar that can be inserted and removed. This segmentation allows the fixed drawbar to provide stable storage reference points while the movable drawbar can be easily inserted for handling and removed when not needed, resolving the contradiction between storage capability and handling ability
2Force
If wedge elements are used to increase contact surface, then holding force is improved, but safety deteriorates
Solution Approach 1:
The drawbar is pre-loaded with a spring force that continuously presses it against the pallet's stop surface. This preliminary action ensures that the drawbar maintains constant contact and form-locking engagement with the pallet before any external forces are applied, preventing the pallet from becoming loose or detached even when the holding force is insufficient
3Measurement precision
If a loose drawbar connection is used to prevent side forces, then position accuracy is improved, but safety deteriorates
Solution Approach 1:
A form-locking connection mechanism acts as an intermediary between the drawbar and the pallet. This mechanism allows axial movement to maintain position accuracy while preventing rotational extraction through geometric interlocking features (such as a keyway or splines), thus mediating between the requirements for loose connection and safety
4Ease of operation
If spring-loaded wedge elements are used for clamping, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The clamping mechanism merges two functions: the spring-loaded elements provide easy operation for clamping, while the integrated form-locking features (such as keyways or splines) provide mechanical safety. This combination ensures that the pallet is both easily clamped and securely locked against extraction, resolving the contradiction between ease of operation and reliability
Data Source
AI summary
A clamping device for machine tools, comprising a chuck (1.1) and a drawbar (1.2) for clamping separate pallets (1.3), with a bayonet-connection via rotational motion of that drawbar (1.2). Rotational motion of the drawbar (1.2) is guided and determined by means (2.5, 2.7, 2.6, 2.4, 2.12, 3) provided in the chuck housing (2.3) interacting with the drawbar (1.2, 2.13). The drawbar (1.2) is turnable mounted in the chuck (1.1) to impede the drawbars extraction out of the chuck, independent if the drawbar (1.2) is in clamping or unclamped condition.