Screw-In Tool Thread Geometry for Stable Holder Clamping
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Solution Overview
Problem
Existing tool arrangements with screw-in tools and tool holders experience instability due to elastic deformation of thread flanks during screwing and clamping, particularly when using brittle materials like hard metal or ceramic, which limits the utilization of thread tensile strength and achieves suboptimal stability.
Innovation Solution
The tool arrangement features threads with different contours that adapt to each other through elastic deformation, ensuring a uniform contact pattern along the thread length, achieved by varying pitch or taper angles, and includes conical support surfaces for enhanced centering and support, allowing for precise positioning and increased stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard threads with identical contours are used for connection, then the connection can be easily manufactured, but elastic deformation during screwing causes non-uniform contact pattern and reduces stability
Solution Approach 1:
The patent applies asymmetry by designing the external thread and internal thread with different thread contours. The external thread has a first thread contour while the internal thread has a second thread contour that differs from the first, creating an asymmetric threaded connection. This asymmetric design ensures that during screwing, the thread flanks deform elastically in a controlled manner to achieve uniform contact across all thread turns, thereby improving connection stability and reliability.
2Strength
If threads are made from brittle materials like carbide or ceramic, then the threads can withstand high loads, but elastic deformation is limited and thread tensile strength cannot be fully utilized
Solution Approach 1:
The patent applies parameter changes by varying the thread contour parameters between the external and internal threads. The external thread contour is specifically designed with different geometric parameters compared to the internal thread contour, allowing controlled elastic deformation in the softer material (steel or cast iron) to compensate for the limited elasticity of brittle materials. This enables full utilization of thread tensile strength while maintaining connection stability when using brittle materials like carbide or ceramic.
3Productivity
If only a few thread turns near clamping surfaces bear the load, then the connection can be formed quickly, but the potential tensile strength of the thread is not utilized
Solution Approach 1:
The patent applies preliminary action by designing the thread contours such that during the screwing process, elastic deformation occurs progressively along the entire thread length. The specific contour design ensures that all thread turns are brought into contact and share the load from the beginning of the clamping process, rather than requiring multiple tightening stages. This preliminary distribution of contact across all thread turns enables both quick connection formation and full utilization of thread tensile strength.
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 enables the full utilization of thread tensile strength, achieving a stable and precise connection by ensuring even contact across the thread length, reducing the risk of slippage and enhancing the service life of the tool holder.
Implementation Method 1
elastic deformation of the thread creates a preload across a portion of the thread, and during clamping, a uniform contact pattern of the thread is achieved over its entire length
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a tool arrangement with a screw-in tool (1) and a tool holder (7), the screw-in tool (1) having a thread (4) for engaging in a counter-thread (11) on the tool holder (7). According to the invention, the mating thread (11) and the thread (4) have different thread contours, so that when they are screwed together they adapt to one another by elastic deformation.