Wire Cutting Force Control for Silicon PV

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Solution Overview

Problem

The high cost and limited lifespan of bonded abrasive wires in diamond wire cutting for silicon photovoltaic applications lead to inefficient cutting speeds and unpredictable wire breakage, exacerbated by material inhomogeneities and empirical optimization methods.

Innovation Solution

A method for wire cutting that involves measuring the force applied to the material and the wire's advancement over time to determine a 'cutting state' quantity, which controls cutting parameters such as wire speed and lubricant delivery to optimize wear reduction and breakage risk, using a device with force sensors and a processing system to adjust parameters in real-time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If bonded abrasive wire is used for cutting silicon, then cutting speed increases significantly, but wire cost increases almost a hundred times compared to smooth wire

Engineering Contradiction:
Improvecutting speedVSAvoidwire cost
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent changes the operational parameters of the wire cutting process by introducing real-time monitoring of cutting force and wire advancement. The system dynamically adjusts cutting parameters based on the measured 'cutting state' quantity, optimizing the balance between cutting speed and wire consumption to reduce overall cost while maintaining high productivity.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If bonded abrasive wire is used, then cutting performance improves, but wire lifespan decreases due to wear and breakage

Engineering Contradiction:
Improvecutting performanceVSAvoidwire lifespan
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The patent implements a feedback control system that continuously measures the cutting force and wire advancement, calculates a 'cutting state' quantity, and uses this information to dynamically adjust cutting parameters. This closed-loop control optimizes wire utilization and extends wire lifespan by preventing excessive wear and reducing breakage risk, while maintaining high cutting performance.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If empirical optimization methods are used for cutting parameters, then implementation is simple, but wire breakage becomes unpredictable and lifespan is reduced

Engineering Contradiction:
Improveparameter setting simplicityVSAvoidwire breakage predictability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces empirical, experience-based parameter optimization with a measurement and calculation system that objectively determines cutting parameters based on real-time data. By measuring cutting force, wire advancement, and calculating the 'cutting state' quantity, the system provides predictable and reliable wire lifespan estimation, eliminating the unpredictability associated with empirical methods while remaining easy to implement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 extends the lifespan of bonded abrasive wires, improves cutting efficiency, and adapts to material inhomogeneities, reducing the risk of wire breakage and optimizing cutting performance.

Implementation Method 1

a device for measuring a force applied by the cutting wire to the material

Methodology Applied
Scientific EffectForce measurement: Force

Implementation Method 2

Cutting is enabled by abrasion phenomena between the wire and the material to be cut

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 3

The abrasive grains are set in motion by the sliding of the two bodies and abrade the material by multiple micro-indentations

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

This method is also generally lubricated by a fluid such as water, polyethylene glycol (PEG), a gel, etc.

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP3049223B1Cutting process and cutting device by wire of a material
Publication Date: 2018.10.31 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3049223B1 patent drawingFigure 1A~1C
  • EP3049223B1 patent drawingFigure 2~3
  • EP3049223B1 patent drawingFigure 4~5

AI summary

The invention relates to a method for wire cutting of a material, wherein a cutting wire is advanced into the material by causing said wire to scroll in such a way as to progressively cut the material, the method being characterised in that it comprises: the measurement of a force applied by the wire on the material as a function of time, the measurement of the advancement of the wire in the material as a function of time, the determination, as a function of said force and said advancement of the wire, of a variable characterising the state of the wire cutting and, servo control of at least one cutting parameter through changes in said variable so as to reduce the rate of wear of the wire and/or to reduce the risk of breaking of the wire. The invention also relates to a device for wire cutting allowing implementation of said method.