Rotary Drill Insert Centering Surfaces for Load-Stable Mounting

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Solution Overview

Problem

Existing rotary drill tool assemblies are prone to premature failure due to stress and fatigue at the support body resulting from significant axial and radial loading forces, as well as torque, which leads to a short operational lifetime.

Innovation Solution

The design features an insert and support body with corner regions having contact surfaces that transmit radial loading forces and provide secure centring, eliminating stress concentration sites, and utilizing a bore configuration to maximize radial clamping leverage and eliminate the need for a slot at the support body jaw, allowing the arms to deform radially for secure engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing drill tool assemblies use conventional mounting interfaces, then the insert can be mounted and replaced, but the support body experiences stress and fatigue from significant loading forces leading to premature failure

Engineering Contradiction:

Improveoperational lifetimeVSAvoidresistance to loading forces

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The mounting interface is segmented into multiple corner regions distributed around the insert perimeter. Each corner region independently transmits radial loading forces to the support body, distributing the total load across multiple contact points rather than concentrating it at a single mounting location, thereby reducing stress and fatigue on the support body

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact surfaces at the corner regions are positioned axially forward of the mounting screw location, transitioning the force transmission from a rearward mounting interface to a forward-facing radial interface. This dimensional repositioning allows the hard insert material to directly bear radial loading forces before they reach the softer support body material

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Force

If the insert is mounted using a mounting screw at the rear, then axial retention is achieved, but radial loading forces create stress concentrations at the support body mounting surfaces

Engineering Contradiction:

Improvetransmission of radial loading forcesVSAvoidstress concentration at mounting surfaces

Core Design Contradiction:

ForceVSStress or pressure

Solution Approach 1:

The corner regions with their contact surfaces act as intermediary elements between the insert and the support body mounting surfaces. These corner regions positioned axially forward of the mounting screw serve as intermediate force transmission points, allowing radial loading forces to be distributed and transmitted through the insert's hard material before reaching the support body, thereby reducing stress concentrations at the actual mounting interfaces

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The corner regions are positioned axially forward of the mounting screw location, establishing force transmission pathways before the loading forces reach the rearward mounting interface. This preliminary positioning of contact surfaces allows the insert to preemptively bear and distribute radial forces, preventing stress concentrations from developing at the support body mounting surfaces

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the insert is securely retained at the support body, then operational stability is achieved, but the insert may become miscentred under radial forces reducing performance

Engineering Contradiction:

Improveretention of insertVSAvoidcentred positional locking

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The corner regions are positioned asymmetrically at the forward-facing perimeter of the insert, creating an asymmetric distribution of contact surfaces that provide both radial force transmission and centring functionality. This asymmetric placement of multiple corner regions around the insert perimeter creates geometric constraints that prevent radial displacement while maintaining rotational symmetry in the overall assembly

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The corner regions with their contact surfaces serve multiple functions simultaneously: they transmit radial loading forces to the support body, provide axial retention in conjunction with the mounting screw, and maintain centred positioning of the insert. This multi-functionality eliminates the need for separate centring features while achieving both secure retention and accurate centring

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11311948B2Rotary drill tool with insert centring surfaces

Publication Date: 2022.04.26 SANDVIK INTELLECTUAL PROPERTY AB

AI summary

A cutting insert for a rotary drill tool and a drill tool assembly in which an insert and a support body are coupled via cooperative contact surfaces and a mounting screw. The contact surfaces provide a dual function to axially and rotationally lock the insert at the support body in addition to providing a centring function of the insert.