Torque-Based Tap Reversal for Faster Thread Forming

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Solution Overview

Problem

Existing thread cutting methods require manual intervention to reverse the direction of rotation for tap removal, which is inefficient and limits the speed of thread formation.

Innovation Solution

A method and apparatus using an electric tool with an electric motor to automatically change the direction of rotation of a thread cutter based on torque measurements, allowing for efficient and automated thread cutting and removal without operator intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual reversal of rotation direction is used to remove the tap, then the device complexity is reduced, but the productivity decreases due to manual intervention

Engineering Contradiction:
Improvethread formation speedVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system monitors its own torque in real-time and automatically determines when to reverse rotation direction based on predetermined torque thresholds, enabling self-controlled tap removal without external manual intervention

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously monitors torque feedback from the motor and uses this information to automatically control the reversal of rotation direction, creating a closed-loop control system that improves productivity while managing complexity through intelligent automation

Inventive Principle:
Principle #23Feedback

2Productivity

If automatic torque-based reversal control is implemented, then the productivity increases through automated tap removal, but the measurement precision requirements increase

Engineering Contradiction:
Improvethread formation speedVSAvoidtorque measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system establishes predetermined torque threshold values in advance that trigger automatic reversal, eliminating the need for real-time complex decision-making and reducing the precision requirements during actual operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses torque as the control parameter and changes the rotation direction based on torque threshold exceedance, transforming a complex multi-parameter control problem into a simpler single-parameter threshold-based control system

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

Enables rapid formation of multiple threads by automatically reversing the tap's direction of rotation, improving efficiency and reducing the time required for thread cutting and removal processes.

Implementation Method 1

an electric motor configured to rotate a thread cutter in a first direction of rotation to cut a thread on a workpiece

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

determining a torque exerted by the electric motor on the thread cutter

Methodology Applied
Scientific EffectTorque measurement: Torque

Data Source

PatentEP4484042A1Method and power tool for thread forming
Publication Date: 2025.01.01 HILTI AG
  • EP4484042A1 patent drawingFigure 1
  • EP4484042A1 patent drawingFigure 2a~2d
  • EP4484042A1 patent drawingFigure 3

AI summary

A method for thread forming with an electric tool (1) comprising the following steps: cutting (S1) a thread (24) on a workpiece (21) by rotating a tap (20, 28) with an electric motor in a first direction of rotation (DR); determining (S2) a torque with which the tap (20, 28) is rotated; determining (S3) a point at which a reversal value of the direction of rotation is reached from the torque; changing (S4) the first direction of rotation (DR) to a second direction of rotation (DR) opposite to the first direction of rotation (DR) after reaching the reversal value of the direction of rotation (DR); and rotating (S5) the tap (20, 28) with the electric motor in the second direction of rotation (DR) to remove the tap (20, 28) from the workpiece (21).