Tapping Tool Reversing Tooth for Chip-Safe Thread Flanks
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Solution Overview
Problem
The existing single-shot tapping process for producing threaded holes often results in material abrasion on the thread flanks due to chip collisions, leading to defects and unreliable screw connections.
Innovation Solution
The tapping tool is designed to manufacture thread flanks with a flank allowance during the tapping stroke, which is then removed in a reversing stroke using a reversing tooth, allowing for a collision contour to guide chips away and ensuring the thread flanks are finished to the correct size, with coordinated tapping and reversing feeds and speeds to optimize the thread profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the single-shot tapping process is used to efficiently produce threaded holes in one stroke, then productivity is improved, but chip collisions cause material abrasion on thread flanks leading to defects and reduced reliability
Solution Approach 1:
The single-shot tapping process is segmented into two distinct strokes: a tapping stroke for core hole creation and initial thread formation, and a reversing stroke for chip removal and thread finishing. This segmentation allows the process to maintain high productivity while eliminating the harmful effect of chip collisions on thread flanks during the finishing operation.
Solution Approach 2:
The core hole and initial thread profile are created in advance during the tapping stroke before chip removal begins. This preliminary action allows chips to be cleared from the hole before the final thread finishing operation, preventing chip-induced abrasion on the thread flanks that would otherwise occur in a traditional single-stroke process.
2Manufacturing precision
If the tapping stroke creates the core hole and internal thread simultaneously, then manufacturing precision is maintained, but chips collide with thread flanks causing material abrasion and defects
Solution Approach 1:
The process uses periodic action by alternating between a forward tapping stroke and a reverse stroke. During the forward stroke, the thread profile is created with precise dimensions. During the reverse stroke, chips are removed and the thread flanks are finished without chip collision, maintaining manufacturing precision while eliminating harmful chip abrasion.
Solution Approach 2:
The process inverts the traditional sequence by first creating the thread profile during the forward tapping stroke, then removing chips and finishing the thread flanks during the reverse stroke. This inversion ensures that chip removal occurs after thread formation, preventing chip collisions from damaging the freshly created thread flanks.
3Productivity
If the thread profile is created during the tapping stroke, then the process is efficient, but the thread flanks are vulnerable to chip damage before finishing
Solution Approach 1:
The thread profile is preliminarily formed during the high-speed tapping stroke to maintain productivity. The newly formed thread flanks are then protected from chip damage during the subsequent reverse stroke, where chips are removed and the thread flanks are finished to the required surface quality and dimensional accuracy.
Solution Approach 2:
The thread creation process is segmented into two phases: rapid thread profile formation during the forward tapping stroke, and precise thread flank finishing during the reverse stroke. This segmentation allows the process to achieve both high productivity in thread formation and high manufacturing precision in thread flank quality.
Data Source
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AI summary
The invention relates to a tapping tool for producing a threaded bore (1) with internal thread (9) in a workpiece (5), wherein the tapping tool has, at the drill tip (25) thereof, a main cutting edge (27) and a thread profile (29) which trails in a tapping direction (I). The method involves a tapping stroke (G), in which the tapping tool (23) is driven with a tapping feed motion (fG) in the tapping direction (I), and with a tapping rotational speed (nG) synchronized therewith, into the workpiece (5), and the tool main cutting edge (27) produces a core hole and the tool thread profile (29) forms an internal thread (9) on the inner wall of the core hole. In the tapping stroke (G), chips (51) are produced which are conveyed out of the threaded bore (1) in a chip discharge direction which is opposite to the tapping direction (I), which chips collide with thread flanks (19) of the internal thread (9) which face toward the chips (51) for discharging. According to the invention, the tool thread profile (29) has at least one reversing tooth (57) by means of which, during the reversing stroke (R), a flank oversize (Δx) can be removed from those thread flanks (19) of the internal thread (9) to be produced which, during the tapping stroke (G), face toward the chips (51) for discharging.