Orbiting Scroll Member Wear Resistance via Local Quality
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Solution Overview
Problem
Conventional methods for manufacturing scroll members using cast iron result in portions with low thickness being susceptible to cooling and wear, leading to potential deformation, and increasing thickness is undesirable as it enlarges the compression mechanism.
Innovation Solution
A method involving semi-molten die casting to form cast iron with a protruding part and specified portions of greater thickness on the external periphery, which are then cut to increase heat capacity and hardness, reducing the difference in hardness between peripheral and central areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the spiraling part is increased to reduce wear and deformation, then the strength and hardness are improved, but the size of the compression mechanism is increased
Solution Approach 1:
The invention applies different thicknesses to different portions of the spiraling part. The external peripheral portion has a greater thickness than the internal peripheral portion, creating local quality variation. This allows the external peripheral portion (which experiences more wear and stress) to have higher strength and hardness, while the internal peripheral portion maintains a smaller thickness to avoid unnecessary size increase of the overall compression mechanism.
2Temperature
If the thickness of the spiraling part is increased to increase heat capacity and resist cooling, then the hardness is improved, but the size of the compression mechanism is increased
Solution Approach 1:
The invention creates local quality variation in the spiraling part by making the external peripheral portion thicker than the internal peripheral portion. The greater thickness at the external periphery provides increased heat capacity and resistance to cooling in the region that experiences the most thermal stress, while avoiding unnecessary size increase in the internal regions where less thermal protection is needed.
3Ease of manufacture
If the thickness of the spiraling part is made uniform, then the manufacturing process is simplified, but the external peripheral portion is susceptible to cooling and wear
Solution Approach 1:
The invention abandons uniform thickness in favor of variable thickness, where the external peripheral portion has greater thickness than the internal peripheral portion. This local quality variation specifically addresses the reliability issue by providing enhanced resistance to cooling and wear where it is most needed at the external periphery, while accepting increased manufacturing complexity as a necessary trade-off for improved performance.
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 method enhances the hardness and strength of the scroll member, making it resistant to deformation and wear, while maintaining a smaller size, thus reducing the likelihood of the compression mechanism breaking down, even when compressing carbon dioxide.
Implementation Method 1
the portion near the external periphery has a greater heat capacity than the portion near the center. Consequently, the portion near the external periphery is more resistant to cooling than the portion near the center
Implementation Method 2
applying unequal cooling of the scroll wrap, thereby causing the hardness of the wrap to vary from radially outside to radially inside
Data Source
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AI summary
An object of the present invention is to reduce wear and deformation in a scroll member. A method for manufacturing an orbiting scroll as a scroll member comprises a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained. For example, the cast iron is formed by semi-molten die casting. In step (b), the iron casting obtained in step (a) is cut and an orbiting scroll is obtained. The iron casting (261) obtained in step (a) has a fixed part (261a) and a spiraling part (261b). In the fixed part (261a), the thickness (d2) of a portion (261a2) near the external periphery is greater than the thickness (d1) of a portion (261a1) near the center (9). The spiraling part (261b) is fixed to the fixed part (261a), and is made to extend in a spiraling formation around the center (9). By performing step (b) on the iron casting (261), a panel is obtained from the fixed part (261a), and a compression member is obtained from the spiraling part (261b).