Furnace Susceptor Compression System for Thermal Expansion Control

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Solution Overview

Problem

Pusher furnaces face issues with adjacent heating sections expanding and contracting at different rates, leading to gaps that allow heat and gases to escape, potentially causing damage and increasing the risk of explosions due to differing thermal and atmospheric conditions.

Innovation Solution

A compression system that applies pressure to maintain contact between adjacent furnace sections using a movable member, actuator, and sensors to monitor and adjust pressure based on thermal expansion and contraction, ensuring continuous abutment and sealing of the sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If heating sections are heated to different temperatures, then processing capability is improved, but gaps form between sections due to differential expansion

Engineering Contradiction:
Improveprocessing capabilityVSAvoidcontact between sections
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies a compression force to the heating sections to compensate for thermal expansion and contraction. This external force parameter change maintains the contact between adjacent sections despite temperature variations and differential expansion, resolving the contradiction between processing capability and structural stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The compression system applies a pre-compression force to the heating sections before thermal expansion occurs. This preliminary counteracting force prevents gaps from forming when sections expand at different rates, maintaining continuous contact while allowing temperature variations for processing

Inventive Principle:
Principle #9Preliminary anti-action

2Stability of the object's composition

If sections are kept in contact during heating, then thermal stability is improved, but sections pull apart during cooling due to contraction

Engineering Contradiction:
Improvethermal stabilityVSAvoidsection contact during cooling
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The compression system dynamically adjusts the compression force to account for both heating and cooling cycles. During cooling, the pre-applied compression force prevents sections from pulling apart despite thermal contraction, ensuring continuous contact and maintaining reliability throughout the entire thermal cycle

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The compression force is applied in advance to counteract the expected thermal contraction during cooling. This preliminary action ensures that when cooling occurs, the sections remain in contact because the compression force has already compensated for the contracting tendency

Inventive Principle:
Principle #10Preliminary action

3Length of moving object

If gaps form between sections, then thermal expansion is accommodated, but heat and gases escape causing damage and explosion risk

Engineering Contradiction:
Improvethermal expansion accommodationVSAvoidheat and gas escape
Core Design Contradiction:
Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The compression system applies a pre-compression force that prevents gaps from forming in the first place. By counteracting the thermal expansion tendency before it can create separation, the system maintains continuous contact between sections, thereby preventing heat and gas escape and eliminating the associated damage and explosion risks

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The applied compression force creates a mechanical constraint that overrides the thermal expansion effect. This parameter change in the mechanical domain prevents the sections from separating during thermal cycling, ensuring continuous sealing and preventing harmful heat and gas escape

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 compression system effectively maintains the integrity of the furnace by preventing gaps between heating sections, containing heat and gases, and reducing the risk of explosions, ensuring consistent thermal conditions for material processing.

Implementation Method 1

the movable member is adapted to keep the susceptors in abutment with each other during contraction of the susceptors during cooling thereof

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

When the individual heating sections are heated, the overall length of the longitudinally extending furnace increases, sometimes by as much as several inches

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP1958482B1Method and apparatus for controlling furnace position in response to thermal expansion
Publication Date: 2013.03.06 AJAX TOCCO MAGNETHERMIC CORPORATION
  • EP1958482B1 patent drawingFigure 1~2
  • EP1958482B1 patent drawingFigure 2A
  • EP1958482B1 patent drawingFigure 3~4

AI summary

A compression system for an inductively heated pusher furnace controls movement of susceptors during thermal contraction thereof. The system includes a plurality of furnace sections each having a susceptor wherein each susceptor abuts an adjacent susceptor and wherein the susceptors include first and last susceptors. A compression plate abuts the first susceptor to apply force thereon toward the last susceptor to keep the susceptors in abutment with each other during contraction of the susceptors during cooling thereof. An actuator for moving the compression plate is preferably automatically controlled by a computerized control system. The susceptors together form a tunnel through which pusher plates travel and have overlapping joints which seal against the escape of gasses and allow for a degree of susceptor contraction without forming a gap therebetween even in the absence of compression of the susceptors.