Shell Mold Gas Permeability for Complex Castings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cast article production methods face challenges with gas defects in complex shapes due to insufficient gas permeability, leading to surface defects and waste generation during the recycling process of sand molds.
Innovation Solution
A structure for producing cast articles comprising amorphous and artificial graphites, inorganic fibers, and a thermosetting resin, with a specific gas permeability range of 6 to 120, which reduces gas defects and enhances hot strength, particularly for complex shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sand molds are used with conventional molding sand and binders, then the mold can retain shape during casting, but gas defects occur in complex-shaped cast articles due to insufficient gas permeability
Solution Approach 1:
The patent employs a shell mold structure with inherently porous characteristics formed from resin-coated sand grains. This porous structure allows gas to escape during casting of complex shapes while the cured resin binder maintains mold integrity and shape retention, directly resolving the contradiction between shape retention and gas permeability.
Solution Approach 2:
The invention uses a composite shell mold structure combining resin-coated sand grains with thermosetting resin binder. This composite material provides both the mechanical strength for shape retention and the gas permeability needed for complex cast articles, eliminating gas defects while maintaining structural integrity during casting.
2Productivity
If sand molds are recycled through reconditioning, then material utilization is improved, but waste material such as dust is generated
Solution Approach 1:
The shell mold structure is designed as a disposable or limited-life component that is used once or a few times and then discarded. This eliminates the need for reconditioning processes that generate dust and waste, as the mold is not subjected to repeated reuse cycles. The low cost of the shell mold material makes this disposable approach economically viable.
Solution Approach 2:
Instead of attempting to recycle and recondition shell molds (which would generate waste dust), the invention adopts a strategy of controlled discarding after limited use. The mold is discarded in a controlled manner without requiring energy-intensive reconditioning processes, thereby preventing waste material generation while maintaining high material utilization efficiency.
3Adaptability or versatility
If cores are used in sand molds, then complex internal shapes can be produced, but handling difficulty increases due to core weight
Solution Approach 1:
The shell mold structure replaces traditional heavy sand cores with lightweight disposable shell cores. These shell cores can be easily handled and positioned due to their low weight, yet still produce complex internal shapes effectively. After serving their purpose, they are discarded without requiring heavy-duty handling equipment.
4Ease of manufacture
If organic fibers are added to improve processability, then the structure becomes more flexible, but hot strength may be compromised
Solution Approach 1:
The patent uses thermosetting resin that undergoes parameter change through curing - transitioning from a flexible, processable state during mold formation to a rigid, high-strength state during casting. This parameter change allows the mold to be easily formed initially while maintaining sufficient hot strength during the casting process, resolving the contradiction between processability and hot strength.
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 structure effectively reduces gas defects in cast articles by allowing controlled gas permeability, maintaining hot strength, and improving the recyclability of materials, while also reducing waste generation.
Implementation Method 1
heating the forming mold to cure the thermosetting resin to form the structure
Implementation Method 2
having a gas permeability of 6 to 120
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention provides a structure for producing cast articles containing one or more inorganic particles selected from amorphous and artificial graphites, an inorganic fiber and a thermosetting resin and having a gas permeability of 1 to 500.