1. Introduction
In the field of modern manufacturing, the demand for efficient and cost-effective casting processes has become increasingly crucial. This is especially true for the production of complex components such as pump shells. Traditional casting methods often face challenges in terms of long production cycles and high costs, which can hinder the development and production of new products. The research and application of fast casting processes aim to address these issues and provide a more viable solution for the manufacturing industry.
1.1 Background of the Research
The development of aerospace and other high-tech industries has placed higher requirements on the quality and performance of aluminum alloy castings. These castings need to have excellent internal and external surface quality, as well as a reasonable internal structure. At the same time, factors such as integration and lightweight design have also become important considerations. For complex aluminum alloy castings, traditional casting processes may not be able to meet the requirements of rapid development and cost control. Therefore, the research on fast casting technologies has become an important topic in the field of casting.
1.2 Objectives of the Study
The main objective of this study is to develop a fast casting process for a certain gear pump shell. This process should be able to shorten the production cycle, reduce production costs, and ensure the quality of the castings. By simplifying the shape of the blank, using 3D printing technology for sand core production, and optimizing the casting process design, we aim to achieve these goals and provide a reference for the production of similar components.
2. Gear Pump Shell Structure and Casting Requirements
2.1 Structure of the Gear Pump Shell
The gear pump shell has a complex structure with features such as internal oil passages that are intertwined, numerous and scattered hot nodes, and significant variations in local wall thickness. The shell has a contour size of , a blank mass of , an average wall thickness of , and a minimum wall thickness of and a maximum wall thickness of . The outer surface of the shell is complex, with evenly distributed reinforcing ribs and concave-convex structures.
2.2 Casting Requirements
The casting of the gear pump shell requires high quality. The inner cavity of the casting should be smooth, without defects such as pores, slag inclusions, shrinkage porosity, and cracks. The casting material selected is ZL101A. After machining, the casting needs to undergo airtight and hydraulic inspections to ensure its performance and quality.
3. Traditional Casting Process and Its Limitations
3.1 Overview of Traditional Casting Process
Traditional casting processes for the gear pump shell typically involve the following steps: first, manufacturing molds, which usually takes a long time. Then, blowing shell cores, performing trial mold scribing, and finally producing and delivering the castings.
3.2 Limitations of Traditional Casting Process
- Long Production Cycle: The production cycle of traditional casting methods is relatively long. For example, the mold manufacturing process alone may take at least 45 days, and from shell core blowing to casting production and delivery, it may take about 14 days, totaling about 60 days. This long cycle cannot meet the requirements of scientific research and production tasks.
| Process Step | Time Required (days) |
|–|–|
| Mold Manufacturing | 45 |
| Shell Core Blowing to Casting Delivery | 14 |
| Total | 60 | - High Costs: Traditional casting requires the production of complex molds, which incurs high costs. For example, a set of metal molds may cost about 200,000 yuan, and a set of shell core box molds may cost about 100,000 yuan.
| Mold Type | Cost (yuan) |
|–|–|
| Metal Mold | 200,000 |
| Shell Core Box Mold | 100,000 | - Low Flexibility: After the first trial production, if there are significant changes to the shell structure, it may lead to the scrapping of metal molds and shell core molds, as they may not be repairable. This lack of flexibility can result in significant losses in the production process.
4. Fast Casting Process Design
4.1 Simplification of Casting Shape
- Inner Cavity Oil Passage Design: According to the shape of the inner cavity oil passage, machining allowances are added to some parts, while the oil passage shape is maintained in non-machining parts. This helps in designing the shape of the sand core and the positioning core head.
- External Shape Simplification: The external shape of the casting is simplified to the maximum extent to accommodate the casting shape with a minimum machining allowance of . A two-part mold can be used for casting after simplification. This not only reduces the complexity of the mold design but also shortens the production cycle.
| Before Simplification | After Simplification |
|–|–|
| Complex Shape, Difficult to Mold | Simplified Shape, Easier to Mold |
4.2 Casting Process Scheme Design
- Adding Risers: Based on the shape of the casting after adding subsidies, risers are added to ensure proper feeding during the solidification process.
- Simplified Metal Mold Design: After simplifying the casting structure, the mold can be designed as a two-part mold, which simplifies the manufacturing process and reduces costs.
4.3 3D Printing of Sand Cores
The sand cores for the shell are produced using 3D printing technology. Due to the suspended oil passages, additional support is required during the post-processing of the printed cores to prevent deformation and ensure the accuracy of the casting.
5. Casting Process Simulation
5.1 Simulation Parameters and Software
The metal mold tilting casting process is used in this study, and the AnyCasting software is employed for simulating the filling and solidification processes. The pouring temperature is set between , and the metal mold temperature is set between .
5.2 Simulation Results and Analysis
- Filling Process: The simulation results of the filling process show that the molten metal fills the mold smoothly. As the filling progresses, the molten metal gradually fills different parts of the mold.
| Filling Stage | Percentage Filled |
|–|–|
| 18% | 18% |
| 36% | 36% |
| 90% | 90% | - Solidification Process: The simulation of the solidification process indicates that the overall solidification of the casting is good. There are no isolated molten pools in the hot spots of the casting, and there are no shrinkage porosity and pore defects. However, the yield rate of the casting is relatively low, with a casting weight of and a riser mass of , resulting in a yield rate of about 57%. By using insulated risers in the future, the yield rate can be improved to above 75%.
| Defect Type | Presence/Absence |
|–|–|
| Isolated Molten Pool | Absent |
| Shrinkage Porosity | Absent |
| Pore Defects | Absent |
6. Casting Pouring Tests
6.1 Test Setup and Procedure
The sand blocks produced are assembled and boxed, and then the casting is poured. After pouring, the pouring and riser systems are removed, and the casting is sandblasted and polished to obtain the final blank.
6.2 Test Results and Analysis
The castings obtained from the pouring tests have a smooth surface, high dimensional accuracy, and no other casting defects. The performance of the castings is compared with that of traditional casting methods, and the results are as follows:
| Comparison Item | Traditional Method | This Method |
|---|---|---|
| Mold Processing Cycle (days) | 45 | 15 |
| Mold Cost (yuan) | 200,000 + 100,000 | 50,000 |
| Casting Trial Cycle (days) | 15 | 7 |
| Casting Qualification Rate (%) | 60 | 85+ |
7. Advantages of the Fast Casting Process
7.1 Shorter Production Cycle
The fast casting process significantly shortens the production cycle. The simplified mold processing takes only 15 days, and the production cycle of the sand core is about 7 days. In contrast, the traditional casting process requires a much longer time.
7.2 Lower Production Costs
The costs of the fast casting process are reduced. The simplified metal mold costs only 50,000 yuan, compared to the high costs of traditional molds. Additionally, the use of 3D printing for sand cores reduces the need for complex shell core box molds, further reducing costs.
7.3 Higher Casting Quality
The castings produced by the fast casting process have higher quality. The simulation and pouring tests have shown that the castings have no defects such as shrinkage porosity and pores, and the surface is smooth and the dimensional accuracy is high.
8. Application and Promotion of the Fast Casting Process
8.1 Application in Gear Pump Shell Production
The fast casting process has been successfully applied in the production of gear pump shells. It has effectively solved the problems of long production cycles and high costs in traditional casting processes, and has ensured the quality of the castings.
8.2 Potential for Promotion in Other Fields
The fast casting process has the potential to be promoted in other fields. For example, in the production of other complex aluminum alloy castings, the principles and methods of this process can be applied to improve production efficiency and reduce costs.
9. Conclusion
In conclusion, the research and application of the fast casting process for the gear pump shell have achieved significant results. By simplifying the casting shape, using 3D printing for sand cores, and optimizing the casting process design, we have shortened the production cycle, reduced costs, and improved the quality of the castings. This process has broad application prospects and can provide a valuable reference for the development and production of new products in the manufacturing industry. Future research can focus on further optimizing the process parameters and exploring the application of new materials and technologies to continuously improve the performance of the casting process.