Refractory Mold Gas Venting for Uniform Heating
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Solution Overview
Problem
Existing refractory molds in investment casting face challenges with maintaining uniform mold temperatures, especially in thin shell molds, leading to defects like misruns, shrinkage, and hot tears due to uneven heating and rapid cooling, and are inefficient in terms of energy usage.
Innovation Solution
A method involving the formation of a bonded refractory mold with gas vents through the mold wall, covered by a gas permeable refractory cover, which allows hot gas to flow through the mold and support medium, ensuring uniform heating and pattern elimination, regardless of mold thickness or gas permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional refractory molds with thick walls are used, then mold strength and thermal retention are improved, but manufacturing time and material cost increase
Solution Approach 1:
The patent applies porous refractory materials with controlled porosity (30-70%) to create thin-walled molds that maintain structural integrity through pore structure. The porous architecture provides mechanical strength while enabling rapid heat transfer, allowing thin walls (0.5-5mm) to replace thick conventional walls without sacrificing strength or thermal performance.
Solution Approach 2:
The patent uses composite refractory materials combining different ceramic particles (alumina, silica, zirconia) with binders to create thin-walled molds with enhanced mechanical properties. The composite structure achieves high strength-to-thickness ratio, enabling rapid manufacturing of thin-walled molds that maintain sufficient strength during casting operations.
2Loss of time
If thin shell molds are used, then material cost and manufacturing time are reduced, but temperature uniformity deteriorates
Solution Approach 1:
The porous structure with 30-70% porosity acts as a thermal conduit, allowing rapid and uniform heat distribution throughout the thin mold wall. The interconnected pore network enables heat to penetrate quickly from the outer surface to the inner cavity, eliminating temperature gradients that plague conventional thin-walled molds.
Solution Approach 2:
The patent changes the thermal parameters of the mold wall by controlling porosity (30-70%) and wall thickness (0.5-5mm) to optimize heat transfer. This parameter optimization allows thin walls to achieve both rapid heating and uniform temperature distribution, resolving the contradiction between thin-wall benefits and temperature uniformity.
3Temperature
If conventional heating methods are used, then mold heating is achieved, but energy efficiency deteriorates
Solution Approach 1:
The porous refractory structure with 30-70% porosity enables efficient heat transfer from the mold outer surface to the inner cavity through the pore network. This reduces the energy required for heating compared to conventional dense materials, as heat penetrates rapidly and uniformly without requiring excessive thermal input or prolonged heating cycles.
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 mold heating cycle times, increases productivity, and improves product quality by maintaining uniform temperatures and efficient heat transfer, minimizing defects and energy wastage.
Implementation Method 1
The gas permeable cover allows the passage of hot gas from the mold cavity through the mold wall and support medium to a region exterior of the mold
Implementation Method 2
hot gas to flow through the mold and support medium, ensuring uniform heating
Implementation Method 3
heating with a hot gas to remove the thermally removable material
Data Source
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AI summary
A method of making a bonded refractory mold is disclosed. The method includes forming a fugitive pattern comprising a thermally removable material. The method also includes forming a refractory mold comprising a mold wall, the mold wall comprising a refractory material and defining a sprue, a gate and a mold cavity, the gate having a gate inlet opening into the sprue and a gate outlet opening into the mold cavity, the mold defined by the fugitive pattern. The method further includes forming a gas vent that extends through the mold wall. The method also includes covering the gas vent with a gas permeable cover.