Cutting Tap With Deburring Grooves For Low Accuracy Holes
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Solution Overview
Problem
Existing cutting taps struggle to form internal threads with high accuracy when the prepared hole has low dimensional accuracy due to sheared and broken surfaces, resulting in uneven thread ridges and excessive rotational resistance, especially when cutting stock is larger than 0.05 mm.
Innovation Solution
A cutting tap design featuring thread ridges with uniform effective diameters and decreasing major diameters, combined with deburring thread grooves that have larger groove bottom diameters than thread ridge effective diameters, allowing for reduced rotational resistance and accurate thread formation even with low dimensional accuracy in the prepared hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the root diameter reliefs are set at 0 or a minute value to ensure accurate guidance of the cutting tap, then the cutting tap can be guided accurately without thread ridge deformation, but the rotational resistance becomes extremely large when cutting stock is 0.05 mm or more
Solution Approach 1:
The patent applies local quality by differentiating the relief characteristics between thread ridges and roots. Thread ridges have 0 or minute effective diameter reliefs for accurate guidance, while roots have larger root diameter reliefs (0.01-0.05mm) to reduce rotational resistance. This localized differentiation allows each element to optimize its function independently.
Solution Approach 2:
The patent changes the parameter of relief diameter from uniform (0 or minute value) to non-uniform, where roots have larger reliefs than thread ridges. Specifically, root diameter reliefs are set at 0.01-0.05mm while effective diameter reliefs remain at 0 or minute value, creating a parameter differentiation that resolves the contradiction between guidance accuracy and rotational resistance.
2Manufacturing precision
If the cutting tap uses minimal cutting stock to maintain precision, then thread formation accuracy is improved, but the cutting tap cannot effectively handle prepared holes with low dimensional accuracy and sheared/broken surfaces
Solution Approach 1:
The patent applies preliminary action by having roots with larger reliefs perform preliminary cutting and removal of sheared/broken surfaces before the thread ridges form the final thread. This preparatory action cleans up the prepared hole surface, enabling subsequent accurate thread formation even when the initial hole has low dimensional accuracy.
Solution Approach 2:
The patent segments the cutting function into two distinct components: roots with larger reliefs for preliminary cutting and material removal, and thread ridges with 0 or minute reliefs for precise thread formation. This functional segmentation allows each component to optimize its performance for its specific purpose.
3Device complexity
If the cutting tap is designed with roots having the same diameter as thread ridges, then structural simplicity is maintained, but the cutting tap cannot form high accuracy internal threads when the prepared hole has sheared and broken surfaces
Solution Approach 1:
The patent applies local quality by giving different relief characteristics to different parts of the cutting tap. Roots have larger diameters with 0.01-0.05mm reliefs for aggressive material removal, while thread ridges have smaller effective diameters with 0 or minute reliefs for precise thread formation. This local differentiation resolves the contradiction between structural simplicity and manufacturing precision.
Data Source
AI summary
A cutting tap includes thread ridges, roots formed between the respective axially adjacent pairs of thread ridges, and a plurality of deburring thread grooves arranged at a constant pitch toward the axial front side of the cutting tap from the rearmost ones of the roots in which the deburring thread grooves are formed, and formed such that a groove bottom diameter of the deburring thread grooves gradually decreases toward the axial front side of the cutting tap. The respective deburring thread grooves have groove bottom diameter reliefs by which the groove bottom dimeter gradually decreases from the front side toward the rear side of each deburring thread groove in the rotation direction of the cutting tap, the groove bottom diameter reliefs being set to be larger than effective diameter reliefs of the thread grooves.