Thread-Cutting Tap Protrusion Reduces Thrust Force
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Solution Overview
Problem
Existing thread-cutting taps face issues with chipping and unstable internal thread accuracy due to increased thrust force during machining, which is exacerbated by chamfered cutting edges.
Innovation Solution
A thread-cutting tap with a protrusion portion at the radially outer end of the chamfered portion, extending along the cutting edge, which reduces the negative thrust force and stabilizes internal thread accuracy by being within a specific width range of 1/80 to 1/20 of the standard thread height, and is formed by plastic deformation of burrs using glass beads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cutting edge is chamfered to restrain chipping, then tool durability is improved, but thrust force increases causing excessive advance and unstable internal thread accuracy
Solution Approach 1:
The cutting edge is divided into multiple functional portions: a chamfered portion for restraining chipping and improving durability, and a protrusion portion for controlling thrust force and maintaining accuracy. This segmentation allows each portion to perform its specific function without interfering with the other, resolving the contradiction between durability and precision.
Solution Approach 2:
Different portions of the cutting edge are given different geometric properties: the chamfered portion has a specific chamfer angle for durability, while the protrusion portion has a controlled protrusion distance for accuracy control. This local differentiation of properties allows simultaneous optimization of both durability and manufacturing precision.
2Duration of action of moving object
If the cutting edge is chamfered to improve tool life, then chipping is restrained, but the negative thrust force increases causing the tap to advance too much
Solution Approach 1:
The cutting edge structure is segmented into a chamfered portion for chipping prevention and a protrusion portion for thrust force control. The protrusion portion specifically addresses the excessive advance problem by providing mechanical control over the cutting depth, thereby reducing the harmful negative thrust force while maintaining the durability benefits of the chamfered portion.
Solution Approach 2:
The protrusion portion acts in advance to prevent excessive advance of the tap by providing a mechanical stop or control mechanism before the full thrust force can cause inaccurate advancement. This preliminary anti-action counteracts the harmful effect of increased thrust force.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The protrusion portion effectively restrains chipping and reduces excessive advance of the tap, thereby stabilizing internal thread accuracy and improving tool durability.
Implementation Method 1
the cutting edge is provided with a protrusion portion at least in a radially outer end portion of the chamfered portion, such that the protrusion portion protrudes from a rake face of the cutting edge forwardly in a rotation direction of the thread-cutting tap
Implementation Method 2
owing to the provision of the protrusion portion, the thrust load acting in the negative direction upon biting of the spiral tap into the work material is reduced, whereby the excessive advance of the spiral tap is avoided
Implementation Method 3
the protrusion portion is a portion that is formed by plastically deforming at least one burr in a blasting operation using glass beads
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
Provided is a thread-cutting tap, which limits chipping that occurs during tapping and with which female thread precision is also stabilized. Chipping is limited by forming a protruding circular shape (32) on the cutting face (30) of a cutting edge (28). Moreover, the thrust load (Fs), which acts on the negative side when the spiral tap (10) bites into the material that is being cut, is reduced and excessive advancement of the spiral tap (10) is also eliminated. Consequently, because spiral tap (10) cutting conditions are favorable, female thread precision is also stabilized.