Rotary Drill Insert Interface for Torque and Fatigue Control

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Solution Overview

Problem

Existing drill tool assemblies face difficulties in mounting and removing inserts, leading to stress and fatigue at the mounting region, resulting in potential shank failure due to inadequate control of loading forces and torque transmission.

Innovation Solution

A drill tool insert with a tine-like interface featuring axial support surfaces that have a first and second declined orientation relative to the plane perpendicular to the longitudinal axis, effectively directing and absorbing torque and axial loading forces, thereby minimizing stress and fatigue while facilitating easy insertion and removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If axial support surfaces are declined relative to a plane perpendicular to the longitudinal axis to maximize axial lock of the insert, then the locking strength is improved, but stress concentrations and fatigue at the mounting region increase leading to shank failure

Engineering Contradiction:

Improvelocking strengthVSAvoidshank failure resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The axial support surface is divided into multiple segments with different decline angles. The first axial support surface has a first decline angle, while the second axial support surface has a second decline angle that is different from the first. This segmentation allows different regions of the support surface to handle different components of the loading forces, optimizing both locking strength and stress distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the axial support surface are given different geometric properties through varying decline angles. The first decline angle is optimized for maximizing axial locking in certain loading conditions, while the second decline angle is optimized for reducing stress concentrations in other regions. This local differentiation of geometric quality allows the single support surface to simultaneously address multiple conflicting requirements.

Inventive Principle:

Principle #3Local quality

2Strength

If the insert is tightly locked at the support body to maximise retention, then the locking strength is improved, but mounting and removal of the insert becomes difficult

Engineering Contradiction:

Improvelocking strengthVSAvoidinsert mounting and removal

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The bayonet-type locking interface provides dynamic locking behavior where the declined axial support surfaces guide the insert during mounting to achieve automatic engagement. The different decline angles create a mechanical advantage that allows the insert to be locked firmly during operation while still permitting controlled removal through rotational motion, thus maintaining ease of operation despite strong locking.

Inventive Principle:

Principle #15Dynamics

3Force

If axial support surfaces are designed to transfer loading forces effectively, then the locking strength is improved, but stress concentrations and fatigue at the mounting region increase

Engineering Contradiction:

Improveloading force transmissionVSAvoidfatigue resistance

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The geometric parameters of the axial support surfaces are optimized by varying the decline angles. The first decline angle and second decline angle are specifically selected to balance force transmission efficiency with stress distribution. By changing these geometric parameters, the support surfaces can effectively transfer loading forces while minimizing stress concentrations that lead to fatigue.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3427877B1Rotary cutting insert and tool having a declined axial support surfaces

Publication Date: 2022.09.28 SANDVIK INTELLECTUAL PROPERTY AB

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AI summary

A cutting insert for a rotary drill tool and drill tool assembly in which an insert and a support body are coupled via a plurality of axial support surfaces. The support surfaces comprise a first declined orientation in the axial direction and a second declined orientation in the circumferential direction so as to manage and control transmission of loading forces at the region of mounting the insert at the support body.