Tool Holder Clamping Mechanism With Variable-Pitch Drawbar Motion
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Solution Overview
Problem
Existing clamping devices for machine tools require significant axial space due to the use of gas springs or hydraulic pistons, making them unsuitable for tool turrets with limited axial space.
Innovation Solution
A compact clamping device design that uses a rotatable actuating member and a motion transferring mechanism with varying pitch contact surfaces to control the axial movement of a drawbar, eliminating the need for gas springs or bulky hydraulic systems, allowing for efficient clamping and releasing of tool holders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If gas springs or hydraulic pistons are used to control the clamping mechanism, then automatic tool changing operation is achieved, but the axial space required increases significantly
Solution Approach 1:
The invention converts the axial movement of the drawbar into a rotary movement of the actuating member. By threading the actuating member onto the drawbar, rotational motion is transformed into axial displacement, allowing the clamping mechanism to be controlled within a compact axial space while maintaining automatic operation capability.
Solution Approach 2:
The actuating member serves as an intermediary between the control system and the drawbar. It translates rotary motion into axial movement through its threaded engagement with the drawbar, eliminating the need for bulky gas springs or hydraulic pistons while achieving automatic tool changing.
2Length of moving object
If a rotatable actuating member with motion transferring mechanism is used, then axial space is reduced, but the mechanism complexity increases
Solution Approach 1:
The actuating member performs multiple functions: it acts as a rotary actuator, a motion transfer element through its threaded engagement, and a control element for the clamping mechanism. This multi-functionality reduces the need for separate components, simplifying the overall mechanism while maintaining compact axial dimensions.
3Force
If the pitch of contact surfaces varies to amplify force, then clamping force increases, but the manufacturing precision requirements increase
Solution Approach 1:
The invention varies the pitch of the contact surfaces along the actuating member to create a force-amplifying effect. The pitch is larger at the beginning of the rotary movement for faster drawbar displacement and smaller towards the end to amplify the clamping force, achieving secure engagement while managing manufacturing precision requirements through deliberate parameter variation.
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 solution enables a compact clamping device that can be used in tool turrets, providing efficient tool changing operations with reduced space requirements and a force-amplifying mechanism for secure clamping, while maintaining self-locking capabilities without external forces.
Implementation Method 1
a motion transferring mechanism configured to transfer a rotary movement of the actuating member in a first rotary direction in relation to the housing into an axial movement of the drawbar from the advanced releasing position to the retracted locking position
Data Source
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AI summary
A clamping device for releasably holding a tool holder shank (91), comprising: - a housing (2); - a drawbar (5) axially moveable in a bore (3) in the housing; - engagement members (20) moveable under the effect of the drawbar into locking engagement with the tool holder shank; and - an actuating member (14) rotatably arranged in the bore. Upon rotation of the actuating member, a contact surface on a motion transferring element (50) fixedly connected to the actuating member achieves an axial movement of the drawbar by pressing against a contact surface on another motion transferring element (40) fixedly connected to the drawbar. At least one of said contact surfaces comprises two sections with mutually different pitch, such that the same angular displacement of the actuating member, when rotated in a first rotary direction, results in a longer axial movement of the drawbar in a first phase of the rotary movement than in a final phase thereof.