Rotatable Cutting Tool Bolster Insert Nesting

Solution Overview

Problem

Rotatable cutting tools experience excessive forces and stresses during machining operations due to the extended length of the cutting insert, leading to tool failure in abrasive and erosive environments.

Innovation Solution

A cutting insert is designed to be at least partially received in a socket of a bolster, with a convex-shaped conical head portion, collar portion, and axially-rearward portion, where between sixty percent and ninety percent of the cutting insert is received in the socket, reducing the transmission of forces and stresses to the cutting tool.

Engineering Contradictions & Design Principles

VSEngineering 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, leading to tool failure

Engineering Contradiction:

Improvematerial removal capabilityVSAvoidtool strength under cutting forces

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The cutting insert is nested within a bolster structure that is received in a socket of the cutting tool body. The bolster has a tapered shank portion that fits into a corresponding tapered bore in the cutting tool body, creating a nested configuration where the cutting insert is supported by the bolster which is in turn supported by the cutting tool body. This nesting arrangement reduces the effective overhang of the cutting insert and distributes cutting forces through multiple structural levels.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The bolster acts as an intermediary component between the cutting insert and the cutting tool body. It provides additional structural support and force distribution, mediating the transmission of cutting forces. The bolster's tapered shank portion and its reception in a tapered bore create a mechanical interface that reduces stress concentration on the cutting tool body while supporting the cutting insert during operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Length of moving object

If the cutting insert extends further from the cutting tool, then the reach and accessibility to difficult-to-reach areas are improved, but the transmission of forces and stresses to the cutting tool increases, causing tool failure

Engineering Contradiction:

Improvecutting insert extension lengthVSAvoidtool strength under cutting forces

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The cutting insert is nested within a bolster structure that is received in a socket of the cutting tool body. The bolster has a tapered shank portion that fits into a corresponding tapered bore in the cutting tool body, creating a nested configuration where the cutting insert is supported by the bolster which is in turn supported by the cutting tool body. This nesting arrangement reduces the effective overhang of the cutting insert and distributes cutting forces through multiple structural levels.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The bolster acts as an intermediary component between the cutting insert and the cutting tool body. It provides additional structural support and force distribution, mediating the transmission of cutting forces. The bolster's tapered shank portion and its reception in a tapered bore create a mechanical interface that reduces stress concentration on the cutting tool body while supporting the cutting insert during operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the cutting insert extends further from the cutting tool, then the cutting effectiveness on hard materials is improved, but the transmission of forces and stresses to the cutting tool increases, leading to tool failure

Engineering Contradiction:

Improvecutting effectiveness on hard materialsVSAvoidtool strength under cutting forces

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The cutting insert is nested within a bolster structure that is received in a socket of the cutting tool body. The bolster has a tapered shank portion that fits into a corresponding tapered bore in the cutting tool body, creating a nested configuration where the cutting insert is supported by the bolster which is in turn supported by the cutting tool body. This nesting arrangement reduces the effective overhang of the cutting insert and distributes cutting forces through multiple structural levels.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The bolster acts as an intermediary component between the cutting insert and the cutting tool body. It provides additional structural support and force distribution, mediating the transmission of cutting forces. The bolster's tapered shank portion and its reception in a tapered bore create a mechanical interface that reduces stress concentration on the cutting tool body while supporting the cutting insert during operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10294786B2Rotatable cutting tool with cutting insert and bolster

Publication Date: 2019.05.21 KENNAMETAL INC

AI summary

A rotatable cutting tool (10) includes a cutting tool body (12) having an axial forward end (14) and an axial rearward end (16). A bolster (46) at least partially received in a head portion (22) and includes a convex-shaped head portion (56) with a socket (20), a collar portion (58) and a tapered shank portion (60). The socket (20) is formed with a substantially planar side wall (20a), a bottom wall (20b), and a radius blend (20c). A hard tip or cutting insert (18) is at least partially received in the socket (20) of the bolster (46) and includes a convex-shaped conical head portion (72), a collar portion (74) and an axially-rearward portion (76) that generally conforms to the geometry of the socket (20) of the bolster (46). Between about sixty percent (60%) and about ninety percent (90%) of the cutting insert (18) is received in the socket (20) of the bolster (46), thereby reducing forces and stresses transmitted to the cutting tool (10) during a machining operation.