Pusher Furnace Alignment Mechanism for Thermal Expansion

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Solution Overview

Problem

Long pusher furnaces used for high-temperature applications face challenges in maintaining thermal expansion and contraction of insulation and susceptor structures, leading to potential jamming and degradation, especially when formed in multiple sections for precise temperature control and continuous movement of pusher plates.

Innovation Solution

The implementation of an alignment mechanism with adjustment assemblies and the use of graphite felt expansion joints to manage thermal expansion and contraction, along with a low-friction graphoil support system to prevent degradation and ensure smooth movement, addresses the issue of maintaining seals and preventing damage during heating and cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the furnace is made lengthy to incorporate necessary heating and cooling zones for precise temperature control, then the temperature profile control is improved, but the alignment tolerance of slide rails and furnace sections becomes more difficult to maintain

Engineering Contradiction:
Improvetemperature profile controlVSAvoidalignment tolerance of slide rails
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The furnace is divided into multiple modular sections that can be assembled in sequence. Each section contains its own slide rail segments, susceptor sections, and insulation components. This segmentation allows for easier manufacturing and assembly while maintaining overall alignment through precise modular interfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces adjustable alignment mechanisms that can modify the positional parameters of slide rail segments relative to each other. This allows for compensation of cumulative alignment errors that occur over the lengthy furnace structure, ensuring continuous smooth movement of pusher plates throughout the entire furnace length.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If the furnace is formed in multiple sections to achieve the necessary length, then the temperature zone control is improved, but the potential for jamming of slide plates increases

Engineering Contradiction:
Improvetemperature zone controlVSAvoidjamming of slide plates
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The slide rail system incorporates dynamic alignment adjustment capabilities that allow the rail segments to adapt to thermal expansion and contraction of the furnace sections. This dynamic adjustment prevents misalignment that would cause jamming of slide plates as they move through the furnace sections during heating and cooling cycles.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The alignment mechanism is pre-configured with adjustment assemblies that can be set before operation to account for expected thermal expansion. This preliminary setup ensures that the slide plates will move smoothly through all furnace sections without encountering binding conditions during the heating process.

Inventive Principle:
Principle #10Preliminary action

3Temperature

If multiple furnace sections are used, then the necessary heating and cooling zones are achieved, but the thermal expansion and contraction of insulation and susceptor structures causes degradation

Engineering Contradiction:
Improveheating and cooling zonesVSAvoiddegradation of insulation
Core Design Contradiction:
TemperatureVSDuration of action of stationary object

Solution Approach 1:

The invention explicitly accounts for thermal expansion by designing the furnace sections with expansion joints and adjustable alignment mechanisms. These features allow the insulation and susceptor structures to expand and contract freely during heating and cooling cycles without generating damaging stresses that would lead to degradation over time.

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The alignment mechanism includes cushioning elements that absorb the stresses generated by thermal expansion and contraction. This beforehand cushioning protects the insulation and susceptor structures from damage during repeated heating and cooling cycles, extending the service life of these critical furnace components.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

4Length of stationary object

If multiple furnace sections are joined together, then the necessary furnace length is achieved, but maintaining thermal seals during expansion and contraction becomes difficult

Engineering Contradiction:
Improvefurnace lengthVSAvoidthermal seals
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

The invention uses flexible sealing elements at the joints between furnace sections that can accommodate thermal expansion and contraction while maintaining continuous thermal seals. These flexible seals allow the sections to move relative to each other during temperature changes without breaking the seal, ensuring continuous operation without damage.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution allows for continuous, damage-free operation of pusher furnaces by maintaining thermal seals and preventing expansion pressures that could damage insulation and structures, ensuring consistent temperature profiles across multiple sections.

Implementation Method 1

allowing the thermal expansion and contraction of an inductively heated susceptor over the length of the furnace sections

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

control the expansion of insulation and other structures within each furnace section

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

maintain these seals during cooling of the furnace, which causes contraction of these various structures

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 4

inductively heated susceptor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 5

inductively heated susceptor

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP1966557B1Furnace alignment system
Publication Date: 2011.08.17 AJAX TOCCO MAGNETHERMIC CORPORATION
  • EP1966557B1 patent drawingFigure 1
  • EP1966557B1 patent drawingFigure 2
  • EP1966557B1 patent drawingFigure 3

AI summary

A pusher furnace includes furnace sections having respective susceptors, a slide rail extending through the furnace sections for sliding pusher plates thereon and an alignment assembly for aligning the susceptors and slide rails of adjacent furnace sections. A support structure spaces the susceptors from insulation therebelow to protect the insulation from degradation from contact with the susceptors. The susceptors are slidably mounted on the support structure to accommodate thermal expansion and shrinkage of the susceptor. The upstream end of the slide rails have beveled upper edges to help prevent the pusher plates from catching thereon. The upstream ends are also laterally tapered to reduce the degree of force encountered should a pusher plate catch thereon. Adjacent insulation members have expansion joints filled with a refractory felt. The susceptors slidably and sealingly engage exhaust ports to allow for thermal expansion and shrinkage of the susceptor without damaging the exhaust port.