Cutting Tool Holder Geometry to Prevent Fastener Torque Damage
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Solution Overview
Problem
Existing cutting tool assemblies face issues with torque-induced damage to fasteners and alignment problems due to tight tolerances, leading to difficulties in disassembly and increased wear.
Innovation Solution
A cutting tool assembly design featuring a tool holder with a cylindrical alignment portion and an eccentric drive member, which includes a fastener hole offset from the longitudinal axis, allowing for secure attachment and easy removal without transmitting torque to the fasteners, and a trigon portion for precise alignment within a mating tool driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conical section is used for alignment in the cutting tool assembly, then precise alignment is achieved, but manufacturing time increases and the tool can lock within the mating tool driver
Solution Approach 1:
The patent removes the conical alignment section from the tool holder design, extracting the problematic element that caused both tight tolerance requirements and tool locking issues. Instead, a cylindrical alignment section is used which provides sufficient alignment without the detrimental effects of conical geometry.
Solution Approach 2:
The patent inverts the alignment approach by using a cylindrical section instead of a conical section. This inversion changes the geometric relationship between the tool holder and mating tool driver, eliminating the self-centering effect of conical surfaces that leads to tight tolerance requirements and potential locking.
2Manufacturing precision
If a conical section is used for alignment, then alignment is achieved, but the fasteners are subjected to high torque and can deform or break
Solution Approach 1:
The patent extracts the conical alignment section that was transmitting excessive torque to the fasteners. By removing this element, the torque path is changed so that fasteners are no longer subjected to the harmful combined loads of alignment forces and cutting torques.
Solution Approach 2:
The patent segments the functional responsibilities by separating alignment (handled by the cylindrical section) from torque transmission (handled by the drive member interfaces). This segmentation prevents the fasteners from bearing the brunt of cutting torques while still achieving precise alignment.
3Manufacturing precision
If tight tolerances are used for the conical section, then proper tool alignment is ensured, but any small deformity or damage invalidates the tool or requires intensive repair
Solution Approach 1:
The patent removes the conical alignment section that required tight tolerances and was sensitive to deformities. The cylindrical replacement is more tolerant of manufacturing variations and damage, significantly improving ease of manufacture and repairability.
Solution Approach 2:
The patent changes the geometric parameters of the alignment section from conical to cylindrical, which fundamentally alters the tolerance requirements. The cylindrical geometry provides alignment functionality with relaxed tolerances, making the tool more robust to manufacturing variations and damage.
4Manufacturing precision
If the conical section increases in size toward the flat collar, then alignment is improved, but the flat collar size is reduced increasing tool cant or tilt
Solution Approach 1:
The patent extracts the conical alignment section whose geometry created the trade-off between alignment precision and collar size. The cylindrical replacement eliminates this geometric conflict, allowing for a larger flat collar that provides better stability while maintaining alignment precision.
Solution Approach 2:
The patent inverts the alignment geometry from conical (increasing size toward collar) to cylindrical (uniform size). This inversion resolves the geometric conflict by providing consistent dimensions that simultaneously achieve alignment precision and maintain adequate collar size for stability.
Data Source
AI summary
A cutting tool assembly includes a tool body and a tool holder including a longitudinal axis around which the tool holder is configured to spin. The tool holder includes a central portion connected to the tool body comprising a fastener hole perpendicular with the longitudinal axis and configured to receive a securing fastener, wherein the fastener hole is offset from the longitudinal axis. The tool holder further includes an eccentric drive member connected to the cylindrical portion. The tool holder can optionally further include an end alignment cylinder connected to the eccentric drive member.