Hydraulic Tool Holder Clamping for Compact Turret Spindles
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Solution Overview
Problem
Existing clamping devices for machine tools are too long and not suitable for use in tool turrets due to limited axial space, making them unsuitable for automatic tool changing operations.
Innovation Solution
A compact clamping device design that uses hydraulic actuators to control the axial movement of a drawbar, eliminating the need for a gas spring and allowing for self-locking during rotation, enabling efficient tool changing without external force requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas spring is used to urge the drawbars into a retracted locking position, then the clamping mechanism can maintain the tool holder securely, but the axial extent of the clamping device becomes relatively long
Solution Approach 1:
The patent removes the gas spring from the clamping device, extracting the component that causes excessive axial length. The clamping function is maintained through alternative means: the drawbar is moved axially by hydraulic actuators to engage disengageable positive engagement members with the tool holder shank, eliminating the need for a gas spring while preserving secure clamping.
Solution Approach 2:
The patent replaces the mechanical gas spring system with a hydraulic actuation system. Instead of using elastic mechanical energy storage in a gas spring, the invention uses hydraulic pressure to move the drawbar axially, engaging positive engagement members that mechanically lock the tool holder in place, achieving both compact dimensions and reliable clamping.
2Ease of operation
If a hydraulic piston is used to displace the drawbars into an advanced releasing position, then the tool holder can be released from the spindle, but the device complexity increases
Solution Approach 1:
The patent combines the functions of tool holder release and drawbar positioning into a single integrated mechanism. The hydraulic actuator directly moves the drawbar axially, which simultaneously disengages the positive engagement members from the tool holder shank and positions the drawbar in the advanced releasing position, reducing device complexity while maintaining ease of operation.
Solution Approach 2:
The engagement members are designed to automatically disengage from the tool holder shank when the drawbar is moved axially by the hydraulic actuator. The mechanism self-regulates the release process through the geometric relationship between the drawbar movement and the engagement member positioning, eliminating the need for additional control components and reducing overall system complexity.
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 compact design allows for effective automatic tool changing operations in tool turrets by reducing frictional forces and maintaining the drawbar in the locked position during spindle rotation, enhancing operational efficiency and space utilization.
Implementation Method 1
two or more hydraulic actuators arranged in or mounted on the housing on different sides of the spindle and configured to move the actuating member axially in relation to the spindle
Implementation Method 2
a motion transferring mechanism arranged inside the housing, wherein the motion transferring mechanism is mounted to the spindle and configured to transfer a movement of the actuating member in a first axial direction in relation to the spindle into a movement of the drawbar
Implementation Method 3
The actuating member is configured to assume a self-locking axial position in or on the spindle when the drawbar has been forced into the retracted locking position, so as to thereby keep the drawbar in the retracted locking position
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A clamping device for releasably holding a tool holder shank (71), comprising: - a spindle (2) rotatably mounted inside a housing (3); - a drawbar (8) axially moveable in a bore (5) in the housing between an advanced releasing position and a retracted locking position; - engagement members (20) moveable under the effect of the drawbar into locking engagement with the tool holder shank; - an actuating member (13) slidably mounted to the spindle; - a motion transferring mechanism (30) for transferring an axial movement of the actuating member into a movement of the drawbar; and - two or more hydraulic actuators (50) arranged in or mounted on the housing on different sides of the spindle and configured to move the actuating member in relation to the spindle; and - a connecting element (60) forming a connection in radial direction between the actuating member and piston members (52a, 52b) of the hydraulic actuators.