Polycrystalline Silicon Fracturing Teeth Geometry

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Solution Overview

Problem

Existing methods for fracturing polycrystalline silicon into desired fragments result in increased powder generation, reducing efficiency and accuracy in achieving the desired fragment size.

Innovation Solution

A method involving a fracturing process between counter-rotating rolls with radially protruding teeth having spherical top surfaces and conical or cylindrical side surfaces, with a fracturing ratio of 1.0 to 1.5, to prevent excessive grinding and powder generation, and a sorting process to refine fragment sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the maximum target size is set as the gap between the roll and the inner surface of the housing or between the rolls, then the fragments can be obtained with controlled size, but the fragments are crammed into the gap and ground, increasing powder generation and deteriorating fracturing efficiency

Engineering Contradiction:

Improvefragment size controlVSAvoidfracturing efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The fracturing teeth are designed with spherical top surfaces instead of flat or sharp surfaces. This curvature allows the teeth to impact the polycrystalline silicon rod at a point contact rather than a line or area contact, reducing the grinding effect and powder generation while maintaining effective fracturing. The spherical shape enables the teeth to roll over the material surface, distributing the impact force more effectively.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention changes the geometric parameters of the fracturing teeth by specifying conical or cylindrical side surfaces combined with spherical top surfaces. This parameter modification optimizes the contact geometry between the teeth and the polycrystalline silicon, reducing excessive compression and grinding while maintaining fracturing effectiveness. The specific shape parameters control the stress distribution during impact.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the fragments are crammed into the gap between the roll and the inner surface of the housing or between the rolls, then the fragments are ground, but this increases powder generation and reduces the efficiency of producing desired size fragments

Engineering Contradiction:

Improvefragment size accuracyVSAvoidpowder generation

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The spherical top surfaces of the fracturing teeth prevent excessive grinding by creating point contact with the material. This curvature design allows the teeth to fracture the polycrystalline silicon through impact rather than through compressive grinding, significantly reducing powder generation while maintaining precise control over fragment size.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention converts the potential harmful effect of material being crammed into the gap by designing teeth shapes that prevent excessive compression. The conical or cylindrical side surfaces with spherical tops transform the compression force into more effective impact fracturing, turning the cramping condition into a beneficial impact mechanism that reduces powder generation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 method effectively controls the maximum target size of fractured fragments, reduces powder generation, and improves the efficiency of producing fragments of precise size, enhancing the conversion efficiency to desired dimensions.

Implementation Method 1

a rod R of polycrystalline silicon is fractured to fragments C of a few millimeters to a few centimeters. In this process, it is typical to break the rod R into appropriate size by thermal shock or the like, and then further hit and break the fragments with a hammer directly.

Methodology Applied

Scientific EffectImpact force: Impact Force

Implementation Method 2

break the rod R into appropriate size by thermal shock or the like

Methodology Applied

Scientific EffectThermal shock: Thermal Shock

Data Source

PatentUS8944353B2Method for producing fractured fragments of polycrystalline silicon

Publication Date: 2015.02.03 HIGH-PURITY SILICON CORP

AI summary

A method for producing fractured fragments of polycrystalline silicon having a fracturing process fracturing fragments of polycrystalline silicon between a pair of rolls which are rotated in a counter direction each other around parallel axes, in which: the rolls have a plurality of fracturing teeth protruding radially-outwardly from outer peripheral surfaces thereof; the fracturing teeth have spherical top surfaces and conical or cylindrical side surfaces; the fracturing process is performed in fracturing ratio of equal to or more than 1.0 to less than 1.5, and the fracturing ratio is specified by a maximum length of polycrystalline silicon before fracturing with respect to a facing distance between the top surfaces of the fracturing teeth at a facing part of the rolls.