Modular Drill Coupling Pin Assembly for Secure Head Bump-Off
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Solution Overview
Problem
Conventional modular rotary cutting tools face issues with securely holding the cutting head due to deformation-based forces, leading to potential loosening during high cutting forces and vibrations, and existing screw-based solutions are complex, costly, and reduce tool stiffness, especially in small drills, requiring tool removal for head replacement.
Innovation Solution
A modular rotary cutting tool design featuring a tool shank with a pocket and a coupling pin assembly, including a sleeve member and coupling pin with a non-circular cross-sectional shape and bump-off surface, which enhances the bump-off capability by distributing stress over a larger area, allowing for secure clamping and easy replacement without removing the tool from the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screw mechanism is used to hold the cutting head, then the cutting head is securely held, but the device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent extracts the screw mechanism from the tool shank and replaces it with a simpler coupling pin assembly. The coupling pin with non-circular cross-section and bump-off surface provides secure retention without requiring complex threading or multiple fastening components, thus maintaining reliability while reducing device complexity
Solution Approach 2:
The patent changes the geometric parameters of the coupling pin by using a non-circular cross-section (such as square or rectangular) instead of a circular one. This parameter change enables the coupling pin to engage with corresponding features in the cutting head and tool shank, providing secure retention through shape complementarity rather than threaded fastening
2Reliability
If a screw mechanism is used to hold the cutting head, then the cutting head is securely held, but the manufacturing cost increases
Solution Approach 1:
The patent removes the expensive screw mechanism and replaces it with a simple coupling pin assembly that can be manufactured using basic machining operations. The coupling pin with non-circular cross-section and bump-off surface requires minimal processing steps, significantly reducing manufacturing cost while maintaining secure cutting head retention
Solution Approach 2:
The coupling pin assembly is designed as a simple, inexpensive component that can be easily manufactured and replaced if needed. By using basic geometric features (non-circular cross-section, bump-off surface) instead of complex threaded fasteners, the patent achieves secure retention at a fraction of the cost of screw mechanisms
3Reliability
If a screw mechanism is used to hold the cutting head, then the cutting head is securely held, but the tool stiffness is reduced
Solution Approach 1:
The patent extracts the screw mechanism from the tool shank and replaces it with a compact coupling pin assembly. This removal of the screw mechanism eliminates the additional components and fastening features that would reduce the structural continuity and stiffness of the tool, while the coupling pin still provides secure cutting head retention through its non-circular cross-section and bump-off surface
4Ease of operation
If a setscrew is used to clamp and bump off the cutting insert, then the cutting insert can be removed, but permanent deformation occurs and component life is reduced
Solution Approach 1:
The patent changes the geometric parameters of the coupling pin by incorporating a bump-off surface with specific dimensions and orientation. This parameter change allows the coupling pin to engage with the cutting head and provide a controlled bump-off action that releases the cutting insert without requiring excessive force that would cause permanent deformation, thus extending component life while maintaining ease of operation
Solution Approach 2:
The coupling pin assembly provides a dynamic retention mechanism where the non-circular cross-section maintains secure holding during machining operations, and the bump-off surface enables easy release when needed. This dynamic system adapts between secure retention and easy removal modes without causing damage to components
5Device complexity
If the cutting head is held by deformation forces of tool shank walls, then the structure is simple, but the cutting head loosens during high cutting forces and vibrations
Solution Approach 1:
The patent applies local quality by providing specific geometric features (non-circular cross-section, bump-off surface) at the coupling pin and corresponding engagement features in the cutting head and tool shank. These localized geometric features create positive mechanical engagement that prevents loosening during high cutting forces and vibrations, while the overall structure remains relatively simple
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 enhanced bump-off capability securely holds the cutting head during machining operations, increases tool life, simplifies manufacturing, reduces operational costs, and minimizes stress on the tool, enabling more efficient and cost-effective machining.
Implementation Method 1
A replaceable cutting head is at least partially disposed within the pocket of the tool shank with an interference fit
Data Source
AI summary
A rotary cutting tool with enhanced bump-off capability is disclosed. The cutting tool includes a tool shank having a pocket. A replaceable cutting head is at least partially disposed within the pocket of the tool shank with an interference fit. A coupling pin assembly is at least partially received within a bore of the tool shank. The coupling pin assembly comprises a sleeve member and a coupling pin at least partially disposed within the sleeve member. The sleeve member includes an upper portion and a lower portion having a non-circular cross-sectional shape with a bump-off surface. An actuation screw contacts the coupling pin assembly and causes the replaceable cutting head to move relative to the tool shank. The bump-off surface of the lower portion of the sleeve member extends radially outward with respect to the coupling pin by a distance, D, thereby providing enhanced bump-off capability.