T-Shaped Tool Tapered Thread Joint for Compressive Shank Loading

Solution Overview

Problem

Conventional T-shaped tools face challenges in securely attaching the cutting head to the shank due to the low tensile strength of cemented carbide, resulting in a rigid connection, which affects machining speed and accuracy.

Innovation Solution

A T-shaped tool design featuring a cemented carbide shank with a tapered external thread and a steel tool body with a tapered internal thread, allowing for a compressive load on the threads and enhancing the connection's rigidity, eliminating the need for end-face contact and increasing fastening torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a fixation screw is used to connect the cutting head to the shank with end-face contact, then the cutting head can be secured to the shank, but the thread lacks rigidity and the connection is not firm due to continuous axial tensile load on cemented carbide

Engineering Contradiction:

Improveconnection strengthVSAvoidthread rigidity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent inverts the loading condition from tensile to compressive by designing the connection interface such that the cutting head is pressed against the shank end face through thread engagement geometry. The tapered thread design causes the fastening force to generate compressive rather than tensile stress on the cemented carbide shank, fundamentally changing the stress state to match the material's strength characteristics.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the thread geometry parameter from standard cylindrical threads to tapered threads. This parameter change modifies the force distribution and stress state in the connection, transforming the loading from axial tension to compression on the shank while increasing the fastening torque and connection rigidity.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the shank is tensioned by the fixation screw with end-face contact, then the cutting head can be attached to the shank, but the axial tensile load continuously exerts stress on the thread reducing connection rigidity

Engineering Contradiction:

Improveattachment easeVSAvoidconnection rigidity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent inverts the loading condition from tensile to compressive by designing the connection interface such that the cutting head is pressed against the shank end face through thread engagement geometry. The tapered thread design causes the fastening force to generate compressive rather than tensile stress on the cemented carbide shank, fundamentally changing the stress state to match the material's strength characteristics.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the thread geometry parameter from standard cylindrical threads to tapered threads. This parameter change modifies the force distribution and stress state in the connection, transforming the loading from axial tension to compression on the shank while increasing the fastening torque and connection rigidity.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional cylindrical threads are used for connection, then the manufacturing is simple, but the fastening torque is insufficient and the connection rigidity is low

Engineering Contradiction:

Improvethread manufacturing simplicityVSAvoidfastening torque

Core Design Contradiction:

Ease of manufactureVSForce

Solution Approach 1:

The patent changes the thread geometry parameter from standard cylindrical threads to tapered threads. This parameter change modifies the force distribution and stress state in the connection, transforming the loading from axial tension to compression on the shank while increasing the fastening torque and connection rigidity.

Inventive Principle:

Principle #35Parameter changes

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 design provides a highly rigid and secure connection, increasing machining speed and accuracy while reducing deformation and manufacturing costs, and allowing for easier tool maintenance and replacement.

Implementation Method 1

the shank and the tool body are connected by engaging the tapered external thread with the tapered internal thread

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a compressive load is exerted on each thread of the tapered external thread of the shank

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS11478864B2T-shaped tool and method for manufacturing T-shaped tool

Publication Date: 2022.10.25 MAKINO MILLING MASCH CO LTD

AI summary

A T-shaped tool is configured by fastening a head having cutting blades to a cylindrical shank, the shank is made of cemented carbide and has a tapered male thread formed at a tip end portion thereof, the tapered male thread becomes smaller in diameter toward the tip end, and the head is made of steel and has a tapered female thread formed therein, and the tapered female thread comes into engagement with the tapered male thread.