Clamping Tool Holder Nub Geometry for Consistent Insert Retention
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Solution Overview
Problem
Conventional clamping tool holders experience excessive stress and deformation due to single-point contact, leading to inconsistent clamping and wear of the clamping nub, which affects the secure retention of inserts.
Innovation Solution
A clamping tool holder design featuring a polygonal nub with two contact surfaces, providing face contact instead of line contact, reduces stress and deformation by distributing the force over a larger area, thereby enhancing clamping consistency and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional clamping nub with single-point contact is used, then the clamping mechanism is simple, but excessive localized compressive stress causes plastic deformation and inconsistent clamping
Solution Approach 1:
The nub contact surface is changed from a single-point (0D) or line (1D) contact to a face contact (2D surface) by forming the nub with a radius approximately equal to the mounting bore radius. This dimensional expansion distributes the clamping force over a larger area, reducing localized stress and preventing plastic deformation while maintaining clamping consistency across multiple insert indices.
2Device complexity
If a clamping nub with line contact is used, then the structure is simple, but high localized compressive stress leads to plastic deformation of the nub
Solution Approach 1:
The contact geometry is transformed from line contact (1D) to face contact (2D) by configuring the nub with a radius matching the mounting bore radius. This increases the contact area, distributing compressive stress and preventing plastic deformation of the nub while keeping the overall structure simple.
3Productivity
If repeated indexing of inserts is performed with a conventional nub, then productivity is maintained, but cumulative deformation reduces clamping retention
Solution Approach 1:
By expanding the nub contact from line to face contact, the stress distribution improves, preventing cumulative plastic deformation that would otherwise occur with repeated indexing. This maintains consistent clamping retention across multiple insert changes without sacrificing productivity.
Solution Approach 2:
The increased contact area of the nub acts as a stress-distributing cushion before excessive localized stress can cause deformation. This preventive design protects against cumulative damage during repeated indexing operations, ensuring long-term clamping reliability.
Data Source
AI summary
A clamping tool holder includes a tool holder body and a clamp for clamping a cutting insert. The clamp causes the cutting insert to press against the bottom and the side walls of an insert-receiving pocket of the tool holder body. The tool holder body has an inclined surface sloping inward in a direction away from the insert-receiving pocket. The clamp has an inclined surface that acts as a ramp with the inclined surface of the tool holder body. When a clamp screw is tightened, a nub of the clamp engages an inside rearward surface of a mounting bore of the insert with face contact and a contact pad engages a top surface of the cutting insert. As a result, the clamp exerts a force downward and rearward force on the insert. In one aspect, the nub has a polygonal cross-sectional shape.