Tilted Green Sand Mold Casting for Large Compressor Rotors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing casting processes for large-scale rotors with a longitudinal axis, such as those for compressors, vacuum pumps, and expander devices, face challenges in avoiding voids and impurities due to complex geometries and gravitational constraints, leading to quality issues and increased production costs, particularly when using green sand molds which are limited in height and prone to collapse under static pressure.
Innovation Solution
A method involving the formation of a green sand mold with a tilted cavity to accommodate the rotor's longitudinal axis, allowing for reduced static pressure and improved flotation of impurities, enabling the casting of large-scale rotors exceeding 650 millimeters in length using a green sand mold by tilting the mold cavity between 5° to 45° relative to the horizontal plane, thereby reducing voids and improving mechanical properties and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vertical casting is used for large-scale rotors, then impurities can be removed through flotation, but the green sand mold collapses under static pressure
Solution Approach 1:
The patent changes the orientation parameter of the mold cavity from vertical to tilted (5-45 degrees from horizontal), which reduces the static pressure on the green sand mold while maintaining sufficient flotation capability for impurity removal. This parameter change allows the use of green sand molds for large-scale rotors that would otherwise be impossible to cast vertically.
Solution Approach 2:
The patent transitions from traditional vertical casting to tilted casting, introducing a new dimensional orientation between horizontal and vertical. This intermediate orientation provides an optimal balance between reducing gravitational pressure on the mold and maintaining buoyancy-driven impurity removal, solving the contradiction between mold strength requirements and casting quality.
2Stress or pressure
If horizontal casting is used for large-scale rotors, then static pressure on the mold is reduced, but impurities and inhomogeneities cannot be removed through flotation
Solution Approach 1:
The patent optimizes the tilt angle parameter (5-45 degrees from horizontal) to achieve a balance where the mold experiences reduced static pressure compared to vertical casting, while still maintaining sufficient gravitational component along the tilt direction to enable impurity flotation and removal through the riser system.
3Device complexity
If the number of risers is limited, then the casting process is simpler, but holes form in the casting due to shrinking during solidification
Solution Approach 1:
The tilted orientation of the mold cavity changes the solidification pattern and shrinkage behavior of the casting, allowing fewer risers to effectively feed molten metal to critical areas. The tilt facilitates more efficient use of riser volume by directing shrinkage compensation along the tilted axis, reducing the number of risers needed while maintaining casting integrity.
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 allows for the successful casting of large-scale rotors with improved surface quality and mechanical properties, balancing weight distribution while reducing production costs and avoiding the limitations of traditional vertical casting methods, enabling the use of green sand molds for larger dimensions without collapsing under static pressure.
Implementation Method 1
impurities that would be present in the molten casting material and/or inhomogeneities that would arise in the mold cavity when the casting material solidifies will not be able to be removed from the mold cavity through flotation on still molten casting material in the mold cavity
Implementation Method 2
the static pressure and impact of the molten casting material on the core and, as such, indirectly on the sand mold, since the height of the core according to a gravitationally vertical direction is greater when casting vertically
Data Source
AI summary
The device according to any of the preceding claims 13 to 19, characterized in that the device is further configured to carry out a method comprising the step of positioning the green sand mold (3), wherein the device is provided with levelling means configured to hold an upper side of the green sand mold (3) during step c in a parallel position in relation to a gravitationally horizontal plane.