Saw-Tooth Buttress Screw Thread for Machining Head Attachment
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Solution Overview
Problem
Machining head replaceable rotating tools face difficulties in removing the machining head from the holder due to adhesion caused by thermal expansion of triangular or trapezoidal threads, especially under conditions generating heat like air blow, which affects attachment strength and ease of replacement.
Innovation Solution
The use of saw-tooth buttress screws with specific flank angles for the fastening male and female screws, along with a removal aiding pin and conical engagement projections/recesses, facilitates easy removal and replacement while maintaining attachment strength, by preventing close contact and adherence during thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If triangular or trapezoidal threads are used for fastening male and female screws, then sufficient attachment strength is achieved, but the threads adhere firmly during thermal expansion making machining head removal difficult
Solution Approach 1:
The patent applies asymmetry by using a saw-tooth buttress thread profile where the leading flank has a different angle than the following flank. The following flank is designed with a smaller angle to prevent adhesion during thermal expansion, while the leading flank maintains sufficient attachment strength. This asymmetric geometry allows the thread to resist tightening forces effectively while minimizing adhesion during heating and removal operations.
Solution Approach 2:
The patent changes the geometric parameters of the thread profile from conventional triangular or trapezoidal shapes to a specific saw-tooth buttress configuration. The following flank angle is optimized to be smaller than the leading flank angle, creating a parameter configuration that reduces adhesion during thermal expansion while maintaining attachment strength during machining operations.
2Object-affected harmful factors
If air blow is used for machining without cooling oil, then environment-friendly machining is achieved, but heat generation causes thermal expansion and adhesion of threads
Solution Approach 1:
The patent converts the harmful effect of thermal expansion into a beneficial outcome by designing the saw-tooth buttress thread with a smaller following flank angle. This geometry allows the thread to accommodate thermal expansion without causing adhesion, effectively converting the heat generation issue into a non-problematic condition during machining head removal.
3Ease of operation
If square thread is used to prevent adhesion, then ease of removal is improved, but sufficient attachment strength cannot be acquired
Solution Approach 1:
The patent resolves this contradiction by creating an asymmetric saw-tooth buttress thread profile. The following flank has a smaller angle to facilitate easy removal and prevent adhesion, while the leading flank has a larger angle to maintain sufficient attachment strength. This asymmetric design combines the benefits of both square threads (easy removal) and triangular threads (strong attachment) without their respective drawbacks.
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 solution allows for easy removal and replacement of machining heads while maintaining predetermined attachment strength, even under conditions that typically cause adhesion, by using saw-tooth buttress screws with optimized flank angles and a removal aiding pin mechanism.
Implementation Method 1
if the screws are thermally-expanded while predetermined machining is performed with the machining head, it is thought that the thread of the male screw increases in a radial dimension and bites into the groove of the female screw, causing flanks on the both sides of the thread to firmly and closely contact with and adhere to flanks of the female screw
Data Source
AI summary
A machining head replaceable rotating tool having a fastening male screw and a fastening female screw disposed on respective shaft centers of one and the other of a machining head and a holder, the fastening male and female screws being threadably engaged with each other to concentrically and removably attach the machining head to a tip portion of the holder, the machining head and the holder being disposed with abutting surfaces abutted against each other in a fastened state when the fastening male and female screws are threadably engaged, the machining head replaceable rotating tool being integrally and rotationally driven via the holder in a tool rotation direction causing the fastening male and female screws to be fastened by a machining load to perform predetermined machining with the machining head, the abutment of the abutting surfaces preventing the fastening male and female screws from being further fastened by a machining load, the fastening male and female screws being saw-tooth buttress screws having a following flank angle α smaller than a leading flank angle β.