Clamping Device Spring Pack Preload and Axial Play Control
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Solution Overview
Problem
Existing clamping devices for machine tools with power-operated chucks face issues with axial play in spring packs, leading to undefined preload and increased complexity, making it difficult to achieve precise clamping force and middle position detection.
Innovation Solution
The integration of spacer elements and stop discs between spring packs and pressure pieces, allowing for adjustable and limited movement, ensures a defined preload and eliminates axial play, enabling immediate clamping force establishment and precise position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spring packs are arranged in holes with diameter larger than the springs to allow axial movement, then the springs can accommodate clamping movements, but axial play occurs and defined preload cannot be maintained
Solution Approach 1:
A guide element is introduced as an intermediary component between the spring packs and the pressure piece. This guide element has a guide opening that receives the spring packs and provides precise guidance, eliminating axial play while maintaining the ability of springs to accommodate clamping movements. The guide element acts as a mediator that resolves the contradiction between movement capability and precision.
2Ease of operation
If the holes in the pressure piece have larger diameter than the springs, then the springs can move axially during clamping, but the springs are not properly guided and axial play occurs
Solution Approach 1:
The guide element serves as a mediator structure that provides proper guidance for the spring packs. Instead of relying on imprecise holes in the pressure piece, the guide element with its guide opening offers accurate guidance while still allowing the necessary axial movement of springs during clamping operations.
3Adaptability or versatility
If two force accumulators with many spring packs are used for both clamping directions, then both internal and external clamping are enabled, but the constructional complexity increases significantly
Solution Approach 1:
The spring packs are designed to serve multiple functions: they provide clamping force for both internal and external clamping operations, and they also serve as elements that can be guided by the guide element to eliminate axial play. This multi-functionality reduces the need for separate force accumulators for different clamping directions.
4Reliability
If the adjustment range of the motion converter is made large to cover the dead travel, then the clamping force can be established after reversing direction, but the adjustment movement required increases
Solution Approach 1:
The guide element is pre-configured with a guide opening that maintains proper alignment and guidance for the spring packs throughout the adjustment range. This preliminary arrangement ensures that when the clamping direction is reversed, the spring packs are already properly positioned and guided, eliminating the need for excessive adjustment range to cover dead travel.
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
This configuration ensures that spring packs are always under preload, allowing for immediate clamping force application and measurement, while restricting spring travel to prevent overload, thus improving the operational efficiency and structural simplicity of the clamping device.
Implementation Method 1
a force accumulator for maintaining the clamping force, which comprises several pre-stressed spring packs
Data Source
AI summary
In a clamping device (1) for machine tools (2) that is equipped with a power-operated chuck (5) and an electric drive motor (11) with a changeover function for triggering clamping movements, a motion converter (31) as well as a force accumulator (51) for maintaining the clamping force, which comprises several spring packs (52) supported on an adjustment element (32) of the motion converter (31), the spring packs (52) are each only arranged on one side of the adjustment element (32). In addition, a pressure piece (53) interacting with the adjustment element (32) is firmly connected to several spacer elements (57), each of which carries a stop disc (61) and passes through the spring packs (52) as well as a spacer (66). The spacer elements (57) and the spacers (66) can be adjusted relative to one another and the spacers (66) interact with spacer pins (71) which are guided through the pressure piece (53) and are supported on the wall (24) of the housing (21) opposite to the spring packs (52).Due to this embodiment, the spring packs (52) are always preloaded and do not have any axial play, and the adjustment movements of the pressure piece can thus be registered and evaluated directly. Rather, the spring packs (52) have a defined preload at all times, with the effect that the operating method is improved compared to embodiments of prior art.