Tapping Tool Thread Flank Collision Contour Design
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Solution Overview
Problem
The existing methods for producing threaded holes often result in material abrasion and defects due to chips colliding with the thread flanks during the tapping process, which can impair the reliability of screw connections.
Innovation Solution
The method involves producing the thread flanks facing the chips with an initial oversize, allowing them to collide with chips during the tapping stroke, and then refining them to the finished size in a subsequent reversing stroke, with coordinated tapping and reversing feed and speed to ensure a load-optimized thread profile design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thread flanks are produced to finished size during the tapping stroke, then the manufacturing precision is improved, but the chips will collide with the finished thread flanks and cause material abrasion and defects
Solution Approach 1:
The thread cutting process is divided into two distinct phases: a roughing stroke that removes the majority of material and creates a collision contour, and a finishing stroke that precisely machines the thread flanks to final dimensions. This segmentation allows each phase to optimize for its specific function without interference from chips.
Solution Approach 2:
The collision contour is deliberately created as a preliminary feature during the roughing stroke. This contour serves as a sacrificial element that chips will collide with during chip evacuation, protecting the finished thread flanks from abrasion while maintaining the structural integrity of the internal thread.
2Productivity
If a single-shot tapping process is used to perform core drilling and internal thread cutting in one stroke, then the productivity is improved, but the chips generated during tapping will collide with the thread flanks and cause material abrasion
Solution Approach 1:
The single-shot tapping process is segmented into two directional strokes: an outward stroke for roughing and chip evacuation, and a returning stroke for finishing. This allows the system to maintain high productivity while addressing chip collision issues through directional separation of functions.
Solution Approach 2:
The chip collision that would normally damage the thread flanks is redirected onto the collision contour, a deliberately created sacrificial feature. This converts the harmful chip abrasion into a controlled interaction that protects the actual thread flanks while maintaining efficient chip evacuation.
3Reliability
If the thread profile is moved out of the tapped hole without stress during the reversing stroke, then the tool reliability is improved, but the chip removal direction causes chips to collide with the thread flanks
Solution Approach 1:
Different regions of the thread profile serve different functions: the collision contour is designed with specific geometric properties to absorb chip impact, while the actual thread flanks are machined to precise dimensions and surface quality. This local differentiation allows the system to tolerate chip collision in specific areas while protecting critical surfaces.
Data Source
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AI summary
The invention relates to a method for producing a threaded borehole (1) in a workpiece (5) with a tapping tool (23) having a main blade (27) on the drill tip (25) thereof and a thread profile (29) trailing in a tapping direction (I), wherein the method involves a tapping upstroke (G) in which the tapping tool (23) is driven into the workpiece (5) with a tapping advancing (fG) in the tapping direction (I) and with a synchronised tapping rotational speed (nG), and the main blade (27) of the tool produces a core borehole and the thread profile (29) of the tool forms an internal thread (9) on the internal wall of the core borehole. Chips (51) are produced in the tapping upstroke (G), which are conveyed out of the threaded borehole (1) in a chip-removal direction opposite the tapping direction (I), and also collide with thread flanks (19) of the internal thread (9) facing the chips (51) to be removed. According to the invention, the thread flanks (19) of the internal thread (9) facing the chips are not yet produced to a final dimension in the tapping upstroke (I), but rather they are produced with a flank measurement (Δx), and in fact they collide with the chips (51) to be removed with the formation of a collision contour (53).