High-Speed Tool Head Clamping to Prevent Knife Jamming
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Solution Overview
Problem
Existing tool heads for machining workpieces at high rotation speeds face challenges with knife positioning and clamping, leading to jamming and lengthy knife changes due to thermal tensions and difficult access, which complicates the clamping process and requires extensive downtime for cooling.
Innovation Solution
A tool head design featuring a knife with a positioning surface interacting with a positioning stop of the base body's positioning spring, aided by a biasing element that presses the knife onto the spring, allowing for one-step positioning and clamping, and incorporating a restoring element for thermal tension compensation, enabling quick and secure knife changes even at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a positioning groove and positioning spring are used to pre-position the blade, then the blade positioning is improved, but the blade becomes wedged and jammed during the clamping process due to residual stresses and thermal distortions
Solution Approach 1:
The patent removes the positioning groove from the blade and the corresponding positioning stop from the positioning spring, eliminating the form-locking pre-positioning mechanism that causes jamming. Instead, only a minimal positioning surface on the blade engages with a positioning stop on the spring, allowing the blade to be inserted freely without wedging during clamping.
Solution Approach 2:
The patent separates the positioning function from the clamping function. The positioning spring only provides a single positioning stop rather than opposing stops, and the blade has only a minimal positioning surface rather than a groove. This segmentation allows independent optimization of positioning and clamping without mutual interference.
2Productivity
If high rotation speeds are used for machining, then productivity is improved, but thermal distortions cause tool parts to jam together, requiring long cooling downtimes
Solution Approach 1:
The patent converts the harmful thermal expansion and distortion effects into a beneficial tolerance buffer. The simplified positioning system with minimal contact surfaces and no form-locking constraints allows thermal distortions to occur without causing jamming, as the components can accommodate dimensional changes freely during the friction-based clamping process.
3Force
If a clamping jaw rotating around a fixed pivot axis is used, then the clamping force is improved, but the positioning groove becomes wedged relative to the positioning spring during closing movement
Solution Approach 1:
The patent removes the positioning groove and opposing positioning stops that create the wedging problem during jaw rotation. The simplified single-point positioning allows the rotating clamping jaw to apply force without causing relative wedging between the blade and positioning spring.
Solution Approach 2:
The patent changes the clamping mechanism from form-locking (positive engagement in positioning groove) to friction-locking (frictional engagement at positioning surface). This parameter change allows the clamping jaw to rotate and apply force without the geometric constraints that cause wedging in the traditional design.
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 design facilitates a secure and efficient knife change process, reduces downtime, and ensures a consistent cutting pattern by compensating for thermal tensions and dimensional changes, allowing for reliable clamping and operation without the need for direct visibility during knife replacement.
Implementation Method 1
a pre-tensioning element is provided for pressing the knife onto the positioning spring and against its positioning stop
Implementation Method 2
the frictional engagement acting in the extension direction, i.e. radially outwards
Implementation Method 3
the positioning spring exclusively forms a positioning stop for the radially inner wall of the positioning groove as a positioning surface
Data Source
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AI summary
A tool head for machining workpieces at high rotational speeds is described, comprising a base body (2) rotatable about an axis (1), which together with a clamping jaw (3) forms a radially outward extending receptacle (4) for the end section (6) of a knife (7) opposite the cutting edge (5).In order to design such a tool head in such a way that, despite operationally induced thermal stresses of the tool parts, a quick and easy knife change can be carried out and at the same time a secure seat of the knife in the holder is enabled despite high rotational speeds, it is proposed that the knife (7) exclusively forms a positioning surface (11) which interacts in the extension direction with a positioning stop (10) of a positioning spring (9) of the base body (2) and that a pre-tensioning element (14) is provided for clamping to press the knife (7) onto the positioning spring (9) and against its positioning stop (10).