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, which provides enhanced bump-off capability by using an actuation screw to securely clamp and remove the cutting head without requiring tool removal 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 becomes complex, expensive, and requires more space reducing tool stiffness
Solution Approach 1:
The coupling mechanism is divided into separate functional elements: a coupling pin with clamping surfaces and a separate actuation screw. This segmentation allows each component to perform its specific function efficiently while keeping the overall structure simple and compact, resolving the contradiction between reliable cutting head retention and device complexity
Solution Approach 2:
The actuation screw is extracted as a separate, removable component from the main tool body. This allows the screw to be easily manipulated for mounting and demounting the cutting head, reducing the complexity of the integrated mechanism while maintaining secure holding capability during operation
2Reliability
If a screw mechanism is used to hold the cutting head, then the cutting head is securely held, but the tool requires more space which reduces stiffness especially in small drills
Solution Approach 1:
The actuation screw is designed to be received within a bore of the tool shank, nesting the fastening mechanism inside the existing tool structure. This eliminates the need for external screw mechanisms that would increase tool length, maintaining stiffness in small drills while providing secure cutting head retention
Solution Approach 2:
The coupling mechanism utilizes the axial dimension of the tool shank bore for screw reception, rather than requiring radial or lateral space. This dimensional arrangement allows the fastening function to be integrated without increasing the overall tool shank length, preserving tool stiffness
3Ease of operation
If setscrew is used to clamp and bump off the cutting insert, then the cutting insert can be removed, but proper positioning is difficult and high forces on small surfaces cause permanent deformation
Solution Approach 1:
The coupling pin is pre-positioned with clamping surfaces that automatically engage the cutting head at the correct position when the actuation screw is tightened. This preliminary positioning eliminates the difficulty of proper alignment during operation, while the distributed clamping surfaces prevent excessive stress concentration that would cause deformation
Solution Approach 2:
The clamping force distribution is changed from concentrated force on small setscrew surfaces to distributed force across larger coupling pin clamping surfaces. This parameter change in force distribution allows adequate clamping and bump-off forces to be applied without causing permanent deformation to the cutting head or tool components
4Adaptability or versatility
If conventional modular design is used with interference fit, then the cutting head can be replaced, but the cutting head may loosen during high cutting forces and vibrations
Solution Approach 1:
The coupling mechanism transitions from a static interference fit to a dynamic actively-controlled connection. The actuation screw can be tightened to apply substantial clamping force on the coupling pin, which in turn applies force on the cutting head through the clamping surfaces. This dynamic adjustment ensures reliable retention during high cutting forces and vibrations while maintaining replaceability by simply loosening the screw
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 design effectively secures the cutting head during machining operations, reducing stress and extending tool life while simplifying manufacturing and reducing operational costs by allowing in-situ cutting head replacement.
Implementation Method 1
An actuation screw contacts the coupling pin assembly and causes the replaceable cutting head to move relative to the tool shank
Implementation Method 2
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, and contacts the actuation screw when moving the replaceable cutting insert from a clamped position to a bump-off position
Implementation Method 3
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.