Bolster-Supported Cutting Insert Geometry for Stronger Braze Joints
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Solution Overview
Problem
Rotatable cutting tools experience excessive forces and stresses during machining operations due to the extension of the cutting insert, leading to potential tool failure.
Innovation Solution
A cutting insert is partially received in a socket of a bolster, with a narrow bottom style geometry provided by the shank portion of the bolster and a tapered geometry by the cutting insert, enhancing the strength of the braze joint between the bolster and the cutting tool body to reduce transmitted forces and stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cutting insert extends further from the cutting tool, then the cutting depth and material removal capability are improved, but the forces and stresses transmitted to the cutting tool increase excessively
Solution Approach 1:
The cutting tool is divided into multiple segments: cutting insert, bolster, and cutting tool body. The bolster acts as an intermediate segment that absorbs and redistributes cutting forces, reducing the stress transmitted to the cutting tool body while maintaining the cutting insert's extended position for effective material removal.
Solution Approach 2:
The bolster serves as an intermediary component between the cutting insert and the cutting tool body. It mediates the force transmission by providing a transition geometry that reduces stress concentration, allowing the cutting insert to extend further without proportionally increasing the forces on the tool body.
2Productivity
If the cutting insert extends further from the cutting tool, then the cutting performance is improved, but the risk of tool failure increases
Solution Approach 1:
By segmenting the cutting tool into insert-bolster-body structure, the system can maintain extended cutting insert position for high productivity while the bolster segment provides structural support and stress distribution to prevent tool failure.
Solution Approach 2:
The bolster geometry parameters (taper angle, radius of curvature, length) are optimized to change the stress distribution characteristics. This allows the cutting insert to extend further for better cutting performance while the modified bolster parameters ensure adequate strength and reliability.
3Ease of manufacture
If a conventional cutting insert geometry is used, then the manufacturing is simpler, but the braze joint strength is insufficient under extreme cutting forces
Solution Approach 1:
The cutting insert geometry parameters (taper angle, radius of curvature, axial length) are modified to create an optimized interface with the bolster. These parameter changes increase the braze joint surface area and improve stress distribution, enhancing joint strength while remaining manufacturable through conventional processes.
Solution Approach 2:
The system uses a composite structure combining the cutting insert material, braze material, and bolster material. This composite approach allows each material to be optimized for its specific function while the combined structure provides the necessary strength to withstand extreme cutting forces.
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 braze joint reduces forces and stresses on the cutting tool, thereby preventing failures during machining operations.
Implementation Method 1
increases the strength of a braze joint between the bolster and the base portion
Data Source
AI summary
A rotatable cutting tool includes a cutting tool body with a head portion. A bolster is at least partially received in the head portion and includes a socket, a collar portion and a shank portion. The socket is formed with a conical side wall and a radius blend. A hard tip or cutting insert is at least partially received in the socket and includes a conical head portion, a collar portion and an axially rearward frustoconical portion that generally conforms to the geometry of the socket of the bolster. The shank portion of the bolster provides a narrow bottom style geometry and the axially rearward frustoconical portion of the cutting insert provides a tapered geometry that together increases the strength of a braze joint between the bolster and the base portion, thereby reducing forces and stresses transmitted to the cutting tool during a machining operation.