Tapping Tool Stroke Separation for Low-Load Threaded Holes
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Solution Overview
Problem
Existing methods for producing threaded holes in workpieces require a time-consuming and process-intensive single-shot tapping process that involves creating both the pilot hole and internal thread in a single stroke, leading to high tool load and prolonged process times.
Innovation Solution
The method involves separating the pilot hole creation from the internal thread creation, where the pilot hole is drilled in one stroke and the internal thread is formed in a subsequent reversing stroke with the same direction of rotation, allowing the tool to remain stress-free and out of engagement with the pilot hole or thread, and utilizing a tapping tool with strategically positioned cutting edges and a thread generating section to minimize load and optimize the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pilot hole and internal thread are created simultaneously in a single drilling stroke, then the process time is reduced, but the tool load increases significantly
Solution Approach 1:
The patent divides the single-shot tapping process into two separate strokes: a drilling stroke for creating the pilot hole and a reversing thread stroke for forming the internal thread. This segmentation allows the tool to engage only the necessary section (drilling section during drilling stroke, thread-generating section during reversing stroke) for each operation, thereby reducing tool load while maintaining productivity
2Ease of manufacture
If the tool reverses direction of rotation when changing from drilling stroke to reversing thread stroke, then the internal thread can be formed, but the process becomes time-consuming and complex
Solution Approach 1:
Instead of reversing the direction of rotation to perform the thread forming operation, the patent maintains the same direction of rotation for both drilling and thread forming strokes. The tool is simply retracted and re-engaged in a reversed axial direction, eliminating the need for rotation reversal and reducing process complexity and time
3Use of energy by stationary object
If the tool drilling section remains engaged with the pilot hole wall during the reversing thread stroke, then continuous cutting action is maintained, but the tool experiences increased stress and load
Solution Approach 1:
The patent extracts the drilling section from engagement with the pilot hole wall during the reversing thread stroke. The tool is retracted axially so that the drilling section is completely disengaged from the workpiece during thread formation, allowing the thread-generating section to operate independently without the additional stress of simultaneous drilling engagement
Data Source
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AI summary
The invention relates to a tapping tool for creating a workpiece tapped hole (1) having an internal thread (9), wherein the rotating tapping tool is drivable into the workpiece (5) during a drilling stroke (B) as far as a setpoint drilling depth (tB), forming a pilot hole (51), and is guidable out of the pilot hole (51) during a reversing drilling stroke (G) with a reversing feed motion and a rotational speed synchronized therewith, forming the internal thread (9), wherein, during the drilling stroke (B), the tapping tool rotates in the same direction as or in the opposite direction to the reversing drilling stroke (G), wherein the tapping tool has a drilling portion (S1, S2) that creates the pilot hole (51) during the drilling stroke (B), and has a thread creating portion (39) that creates the internal thread (9) during the reversing drilling stroke (G), wherein, during the drilling stroke (B), the tool thread generating portion (39) remains unloaded and not in engagement with the pilot hole wall, and during the reversing drilling stroke (G), the tool drilling portion (S1, S2) remains unloaded and not in engagement with the internal thread (9) created.