The high pressure valve is one of the main components of the oil production and gas production wellhead device, and its body structure is shown in Figure 1. Technical requirements: Castings must not have casting defects such as cracks, shrinkage cavities and inclusions. Leakage is not allowed after 70MPa hydraulic pressure test; non-machined surfaces need to be tested for phosphors, no cracks are allowed; the machined surface needs to be wet. Magnetic particle inspection does not allow the presence of inclusions, pores, and cracks. Material is ZG1Cr13.
1. Process comparison and use of heat riser
A company has been engaged in the production of high-pressure valve castings for many years, and has adopted the following three process schemes for production testing.
(1) The use of water glass quartz sand, because quartz sand has not been used very well so far, so when the valve body cavity processing, sanding often occurs, the surface quality is also very poor, and micro cracks often occur during flaw detection.
(2) The water glass quartz sand core is used, and the hot seat of the casting seat is isolated. The method of placing the riser on the top is required, but the size of the riser is large, it is difficult to remove, and the casting process yield is only 50%. Sand is difficult and very uneconomical.
(3) Using fur? Resin sand is used as the core sand, and the process of insulating the riser is adopted in the side flange and the upper part of the valve seat. Because of fur? Resin sand has slow heat conduction, and the heat preservation effect of the heat preservation riser is not obvious, so the size of the riser is relatively large, and the core sand of the valve seat part causes a large amount of gas generation due to the heat of the top riser, which often causes the part to be compressed. The hole is scrapped.
2. Application of fever riser
In view of the above situation, we use the hot riser for ZG1Cr13 high-pressure valve body castings, and the cores are all fur? Resin sand is placed on the top of the middle flange and the side flange. The valve seat is cooled by cold iron, and the tail is also cooled by external cold iron. The ZG1Cr13 high pressure valve casting is successfully produced. The structure of the casting is dense by anatomizing and coloring the casting body. Nearly 000 pieces have been produced, and the casting process yield rate is 78%-80%, and the genuine rate is over 96%.
3. Conclusion
Using fur? The surface of the casting produced by resin sand is smooth and accurate, but due to its slow heat conduction, if the ordinary fiber type heat-insulating riser is used, the heat preservation effect is not obvious. For high-alloys such as ZG1Cr13, etc., it is required to densely form the pressure-bearing steel castings of Figure 4. The use of heat-generating feeders has obvious heat preservation performance, which can significantly reduce the size of the riser, improve the process yield of castings, and reduce gas cutting, gouging, etc. The workload of the process, while the size of the riser is small, reduces the thermal impact on the sand core, can greatly reduce the probability of occurrence of the gas shrinkage hole, the genuine rate of the casting is obviously improved, and the economic effect is obvious.
1. Process comparison and use of heat riser
A company has been engaged in the production of high-pressure valve castings for many years, and has adopted the following three process schemes for production testing.
(1) The use of water glass quartz sand, because quartz sand has not been used very well so far, so when the valve body cavity processing, sanding often occurs, the surface quality is also very poor, and micro cracks often occur during flaw detection.
(2) The water glass quartz sand core is used, and the hot seat of the casting seat is isolated. The method of placing the riser on the top is required, but the size of the riser is large, it is difficult to remove, and the casting process yield is only 50%. Sand is difficult and very uneconomical.
(3) Using fur? Resin sand is used as the core sand, and the process of insulating the riser is adopted in the side flange and the upper part of the valve seat. Because of fur? Resin sand has slow heat conduction, and the heat preservation effect of the heat preservation riser is not obvious, so the size of the riser is relatively large, and the core sand of the valve seat part causes a large amount of gas generation due to the heat of the top riser, which often causes the part to be compressed. The hole is scrapped.
2. Application of fever riser
In view of the above situation, we use the hot riser for ZG1Cr13 high-pressure valve body castings, and the cores are all fur? Resin sand is placed on the top of the middle flange and the side flange. The valve seat is cooled by cold iron, and the tail is also cooled by external cold iron. The ZG1Cr13 high pressure valve casting is successfully produced. The structure of the casting is dense by anatomizing and coloring the casting body. Nearly 000 pieces have been produced, and the casting process yield rate is 78%-80%, and the genuine rate is over 96%.
3. Conclusion
Using fur? The surface of the casting produced by resin sand is smooth and accurate, but due to its slow heat conduction, if the ordinary fiber type heat-insulating riser is used, the heat preservation effect is not obvious. For high-alloys such as ZG1Cr13, etc., it is required to densely form the pressure-bearing steel castings of Figure 4. The use of heat-generating feeders has obvious heat preservation performance, which can significantly reduce the size of the riser, improve the process yield of castings, and reduce gas cutting, gouging, etc. The workload of the process, while the size of the riser is small, reduces the thermal impact on the sand core, can greatly reduce the probability of occurrence of the gas shrinkage hole, the genuine rate of the casting is obviously improved, and the economic effect is obvious.
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