Tapping Tool Thread Profile to Prevent Chip-Damaged Flanks
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Solution Overview
Problem
In one-shot tapping processes, chips produced during the tapping stroke can collide with and damage the thread flanks of the internal thread, leading to material abrasion and flaws in the thread, which negatively affect the reliability of screw connections.
Innovation Solution
The tapping tool is designed to produce the chip-facing thread flanks with a flank allowance during the tapping stroke, which is then removed to the finished dimension in a reversing stroke, using a reversing tooth to form the thread flanks without premature tool breakage, and the thread profile is optimized with different cutting teeth and a circumferential groove to reduce load and ensure a durable thread profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thread flanks are produced to finished dimension during the tapping stroke, then the thread profile is complete, but chips collide with and damage the thread flanks causing material abrasion and flaws
Solution Approach 1:
The patent applies preliminary action by producing the thread flanks with a flank allowance (oversized dimension) during the tapping stroke, intentionally leaving excess material that will be removed later in the reversing stroke. This prevents chips from damaging the final thread geometry during the tapping operation, as the chips collide with the allowance rather than the finished thread surface.
Solution Approach 2:
The patent inverts the conventional sequence by producing the thread profile in two stages: first creating the thread with an oversized flank allowance during the forward tapping stroke, then removing the allowance during the reversing stroke. This reversal of the finishing operation to the return stroke eliminates chip damage to the final thread surface.
2Productivity
If a one-shot tapping process is used to produce both core bore and internal thread in one stroke, then productivity increases, but chip collision with thread flanks causes material abrasion
Solution Approach 1:
The one-shot tapping tool produces the thread profile with a flank allowance during the forward stroke, preparing the thread geometry in advance. The excess material serves as a protective buffer that absorbs chip collision, ensuring the final thread surface remains intact while maintaining the productivity benefits of the one-shot process.
Solution Approach 2:
The patent uses periodic action by utilizing both the forward tapping stroke and the reversing stroke for different functions: the forward stroke produces the thread profile with allowance, and the reversing stroke removes the allowance to finish the thread flanks. This periodic utilization of the tool stroke sequence enables both high productivity and high thread quality.
3Manufacturing precision
If the thread profile is produced with full engagement during the tapping stroke, then the thread form is complete, but the chips cause material abrasion on the thread flanks
Solution Approach 1:
The thread profile is preliminarily formed with an oversized flank allowance during the tapping stroke. This preliminary formation allows the chips to collide with the allowance material rather than the final thread surface, protecting the thread form accuracy while maintaining complete thread engagement during the forward stroke.
Solution Approach 2:
The flank allowance acts as an intermediary material layer between the chips and the final thread surface. During the tapping stroke, chips collide with this intermediary allowance rather than the finished thread flanks, preventing direct abrasion of the critical thread geometry while the allowance is subsequently removed in the reversing stroke.
Data Source
AI summary
A tapping tool for producing a threaded bore having an internal thread in a workpiece. The tapping tool has a main cutting edge on its drill tip and a thread profile trailing in a tapping direction. The method has a tapping stroke in which the tapping tool is driven into the workpiece at a tapping feed rate in the tapping direction and at a tapping speed synchronized therewith and the main cutting edge of the tool produces a core hole bore and the tool thread profile forms an internal thread on the inner wall of the core hole bore. Chips are produced in the tapping stroke, which are conveyed out of the threaded bore in a chip removal direction opposite to the tapping direction and collide with thread flanks of the internal thread facing toward the chips to be removed.