Internal Thread Cutting with Controlled Deceleration Reversal
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Solution Overview
Problem
The existing method for producing internal threads using a single-shot tapping tool results in excessive cutting load, leading to potential tool breakage due to the sudden reduction in tapping speed to zero, causing axial forces that reduce tool service life.
Innovation Solution
A method that involves a controlled deceleration process during the groove forming step, where the axial feed is adjusted as a function of the tool's angle of rotation, reducing the axial feed to less than the thread pitch and eventually to zero at the reversal point, allowing the thread cutting tooth to rotate without stress and preventing tool breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tapping speed is suddenly reduced to zero at the end of the groove forming step, then the tool can be reversed for retrieval, but excessive axial forces are generated causing tool breakage and reduced service life
Solution Approach 1:
The patent applies dynamics by transitioning from a static sudden stop to a dynamic controlled deceleration process. The axial feed is continuously reduced through multiple deceleration steps with decreasing feed rates, allowing the tool to gradually slow down while minimizing inertial forces and axial loads on the thread cutting tooth, thereby preventing tool breakage and extending service life
Solution Approach 2:
The patent changes the parameter of axial feed rate from a constant high value to a progressively decreasing value through multiple deceleration steps. By adjusting the feed rate parameters (first deceleration feed rate, second deceleration feed rate, etc.) and the number of deceleration steps, the system optimizes the deceleration process to reduce axial forces while maintaining control, resolving the contradiction between reliable tool operation and force reduction
2Manufacturing precision
If the axial feed is maintained at thread pitch level during groove forming, then the thread pitch is maintained, but excessive cutting load is generated leading to tool breakage
Solution Approach 1:
The patent applies dynamics by implementing a multi-stage deceleration process where the axial feed rate is progressively reduced through several steps. This dynamic approach allows the thread pitch to be maintained during active cutting while gradually reducing the feed rate during groove forming, thereby maintaining manufacturing precision without generating excessive cutting loads that would compromise tool strength
Solution Approach 2:
The patent applies preliminary action by performing deceleration steps before the tool fully engages in groove forming. The axial feed is reduced to less than the thread pitch in advance through multiple deceleration phases, preparing the system for safe reversal while maintaining thread pitch accuracy during the critical cutting phases, thus preventing tool breakage before it occurs
Data Source
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AI summary
The invention relates to a method for producing a screw thread having a predefined thread pitch and a predefined thread profile in a workpiece, wherein the axial advancement of the tool is smaller in magnitude than the thread pitch during a part of the braking motion before the reversal point. As a result of said braking motion, the thread-producing region (4) produces at least one peripheral extending groove or peripheral groove or circumferential groove in the core hole wall in a way that is actually atypical or extrinsic to function. Therefore, besides being described as a braking process, the process can also be described as a circumferential groove production or peripheral groove production or undercut motion, or as a cutaway motion in the case of a purely cutting tool.