Threaded Section Machining Using Thermal Expansion History

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Solution Overview

Problem

Existing machining methods for threaded sections face challenges in maintaining consistent lead due to thermal expansion, especially during short machining times, requiring expensive and precise equipment for effective feedback control.

Innovation Solution

A machining method and device that uses history information to predict thermal expansion based on past data, adjusting machining conditions to prevent lead variation by calculating correction values for rotational speed and feeding speed, allowing for consistent thread formation without real-time feedback control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If real-time feedback control is implemented to correct thermal expansion during machining, then manufacturing precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvethread lead consistencyVSAvoidcontrol system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by measuring thermal expansion during machining and storing the data, then using this historical data to predict and correct thermal expansion in subsequent machining operations. The correction values are calculated in advance based on accumulated measurement data, allowing the system to compensate for thermal effects without requiring complex real-time feedback control during each machining operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating a database of thermal expansion characteristics from previous machining operations. This historical data serves as a model that can be referenced and applied to predict thermal behavior in future operations, eliminating the need for expensive real-time measurement and control systems while maintaining manufacturing precision.

Inventive Principle:
Principle #26Copying

2Manufacturing precision

If expensive high-precision equipment is used for real-time thermal expansion control, then manufacturing precision is improved, but productivity decreases due to complex control requirements

Engineering Contradiction:
Improvethread lead accuracyVSAvoidmachining efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements self-service by allowing the machining system to automatically accumulate thermal expansion data from its own operations and use this data to self-correct future machining parameters. The system learns from its own historical performance and autonomously adjusts correction values without requiring external intervention or complex real-time control systems, thereby maintaining precision while improving productivity.

Inventive Principle:
Principle #25Self-service

3Productivity

If machining speed is increased to improve productivity, then thermal expansion effects become more significant, but manufacturing precision deteriorates

Engineering Contradiction:
Improvemachining speedVSAvoidthread lead consistency
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies feedback by continuously measuring thermal expansion during machining operations and using this information to calculate correction values. The measured thermal expansion data is fed back into the control system, which then adjusts machining parameters for subsequent operations to compensate for thermal effects, maintaining manufacturing precision even at higher machining speeds.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses parameter changes by dynamically adjusting machining parameters based on accumulated thermal expansion data. The system modifies correction values for rotational speed and feeding speed based on historical thermal behavior patterns, allowing the system to maintain precision across varying machining speeds without requiring constant real-time intervention.

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

This approach reduces equipment costs and machining costs by maintaining consistent thread lead formation across varying thermal expansion, eliminating the need for high-precision control and expensive equipment, even during short machining times.

Implementation Method 1

the machined article 19 undergoes thermal expansion as the temperature of the article 19 being machined increases

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2959997B1Machining method for threaded section and machining device
Publication Date: 2019.10.30 NSK LTD
  • EP2959997B1 patent drawingFigure 1~2
  • EP2959997B1 patent drawingFigure 3(a)~3(b)
  • EP2959997B1 patent drawingFigure 4

AI summary

The present invention prevents the occurrence of variation in the lead of a threaded section of a machined article (19a) resulting from the effects of thermal expansion of the machined article (19a) during machining. A thermal expansion amount that relates to the axial direction of the machined article (19a) during machining is measured by measurement means (13), history information for the thermal expansion amount that relates to the machined article (19a) during machining is obtained from the result of the aforementioned measurement, and a control unit (17a) determines the relative rotational speed of a rotary drive shaft (11) or the feeding speed of an axial feeding device (16a) with respect to the next machined object (19a) that is to be machined on the basis of the history information for the thermal expansion amount of the machined object (19a) that has been machined.