1. Production examples of Shanghai Heavy Machinery Factory Co., Ltd
Located in Minhang District of Shanghai, Shanghai Heavy Machinery Works Co., Ltd. is the largest production base of steel castings and casting refined steel ingots in East China. Relying on the strong rough machining capacity, machining equipment and advanced modern testing facilities of Shanghai Heavy Machinery Works Co., Ltd., it provides all kinds of carbon steel, high and low alloy steel, high and low alloy steel, high and low alloy steel for power stations, nuclear power, shipbuilding, metallurgy, mining, electrical machinery, chemical industry and other fields Stainless steel and other large steel castings and cast ingots. The steel castings produced have complex structure, wall thickness and heavy weight, and the heaviest steel castings are up to 450 tons. Before 2005, the factory has been using the traditional CO 2 sodium silicate sand, which has been difficult to meet the quality requirements and environmental protection requirements of super large steel castings because of its poor storage, difficult sand production and difficult recycling of old sand. Therefore, after a lot of research, analysis and comparison from environmental protection, quality, cost and other aspects, it was decided to use ester hardened sodium silicate sand instead of CO 2 sodium silicate sand. After more than two years of process tests, the plant has successfully applied ester hardened sodium silicate sand to super large steel castings, which has significantly improved the quality of castings and achieved remarkable economic benefits.
| Project | Ester hardened sodium silicate sand | |
| Casting quality | Dimensional accuracy | Good |
| Casting quality | Surface quality | Good |
| Casting quality | Stomatal tendency | Low |
| Casting quality | Hot cracking tendency | Small |
| Casting quality | Comprehensive quality | Good |
| Casting quality | Casting defects | Basically free of defects |
| Reuse of old sand | Comprehensive regeneration rate /% | Seventy |
| Labor and environmental protection | Core collapsibility | Preferably |
| Labor and environmental protection | Casting cleaning | Easily |
| Labor and environmental protection | Working conditions | Good |
| Labor and environmental protection | Environmental pollution | Small |
| Labor and environmental protection | Environmental protection | Best |
| Economic evaluation | Cleaning, welding, repairing, heat treatment and other costs | Lower |
| Economic evaluation | Scrap cost | Low |
| Economic evaluation | Comprehensive cost | Low |
| Process evaluation | Process reliability | Economical and reliable |
| Process evaluation | Process Progressiveness | More advanced |
The plant selects two 30 t mobile continuous sand mixers and one 5 T continuous sand mixer (mixing chromite ore) to produce a batch of super large steel castings such as the upper beam, moving beam, lower beam (of which the upper beam casting weighs 453 T), 600 MW steam turbine cylinder block, 300000 t tanker rudder arm, 4300 mm wide and thick plate binding machine frame of 16500 t oil press. The practice shows that the application of ester hardened sodium silicate sand in the production of large steel castings is completely feasible. Its advantages are shown in Table 1.
2. Production examples of Ningxia shared Cast Steel Co., Ltd
Ningxia shared Steel Casting Co., Ltd. is a large steel casting manufacturing enterprise jointly established by Ningxia shared group, Great Wall xuqi Casting Co., Ltd. and Austria VAI casting (Linz) Co., Ltd. The company mainly provides all kinds of carbon steel, alloy steel and other large steel castings for steam turbines, gas turbines, compressors and other products. The steel castings produced are complex in structure and heavy in weight. The heaviest steel castings reach 150 tons, and the overall dimension of castings is 11500 mm × 6 000 mm × 4 500 mm。 After many investigations and analyses at home and abroad, and visits to large foreign steel casting enterprises, according to the characteristics of the company’s steel castings and the actual application at home and abroad, the factory determined that all castings adopt the production method of furan resin sand molding, core making process, and the combination of ground modeling and pit modeling, with an annual output of 10000 tons of qualified steel castings. After several years of production and application, the large steel castings produced by the company with furan resin sand have reached the best quality level of similar foreign products, which has improved the competitiveness for export and foreign exchange earning.
Using furan resin sand to produce large steel castings is a more advanced process. It has the advantages of easy sand removal, accurate casting size, good surface quality, convenient operation and high production efficiency. It has been widely used in steel casting production abroad and more widely in China.
| Project | Dose |
| Addition of new sand /% | 10 |
| Resin addition amount /% | 0.9-1.1 |
| Dosage of curing agent (resin) /% | 40-60 |
| Ignition loss of regenerated sand /% | 1.6-2.0 |
| Recycled sand powder content /% | 0.8 |
| Sand temperature / ° C | 30 |
Actual production. The project was put into operation in 2006. Furan resin sand process has been applied to produce more than 100000 tons of various types of large steel castings, and has accumulated rich production experience. The indexes of furan resin sand process are shown in Table 2, and the advantages are shown in Table 3.
| Project | Furan resin sand | |
| Casting quality | Dimensional accuracy | Good |
| Casting quality | Surface quality | Good |
| Casting quality | Stomatal tendency | Large |
| Casting quality | Hot cracking tendency | Large |
| Casting quality | Comprehensive quality | Preferably |
| Casting quality | Casting defects | Hot cracks and pores |
| Reuse of old sand | Comprehensive regeneration rate /% | ≥90 |
| Labor and environmental protection | Core collapsibility | Good |
| Labor and environmental protection | Casting cleaning | Easiest |
| Labor and environmental protection | Working conditions | Difference |
| Labor and environmental protection | Environmental pollution | Large |
| Labor and environmental protection | Environmental protection | Difference |
| Economic evaluation | Cleaning, welding, repairing, heat treatment and other costs | High |
| Economic evaluation | Scrap cost | Higher |
| Economic evaluation | Comprehensive cost | High |
| Process evaluation | Process reliability | Poor reliability |
| Process evaluation | Process Progressiveness | More advanced |
3. Production examples of China Second Heavy Machinery Group Corporation
For a long time, the traditional sodium silicate sand molding process has been mainly used in the casting process of double cast steel parts, with low production capacity and quality level. In 2001, Erzhong invested 150million yuan to carry out the “Ninth Five Year Plan” reconstruction and expansion project of casting, thoroughly reformed the molding process, took the lead in adopting the alkaline phenolic resin sand process in the molding and core making of large steel castings of cylinder type in China, and added a new alkaline phenolic resin sand production line. After the project was put into operation, the production capacity of Erzhong’s cylinder was increased from 60 sets per year to 84 sets, and the product quality reached the domestic first-class level. Ge Siemens in Germany, Hitachi in Japan and other large companies have begun to use double cylinders. In recent years, Erzhong has successfully used alkaline phenolic resin sand process to produce high-quality castings for hydropower, thermal power and nuclear power. In January, 2007, Erzhong successfully used the alkaline phenolic resin sand process to produce the upper crown and lower ring castings of Pengshui turbine for Tianjin Alstom company. The maximum outer diameter of the upper crown is 7.07 m, the height is 2.56 m, and the net weight is 83.97 T; The maximum outer diameter of the lower ring is 8.03 m, the height is 1.87 m, and the net weight is 46.82 T. all of them are made of stainless steel. The successful production of this product marks that Erzhong has fully mastered the production technology of producing large steel castings such as the upper crown and lower ring of super large hydropower unit turbines with resin sand process. By the end of 2007, Erzhong has the ability to produce five sets of 700 MW hydropower unit turbine castings per year, and has become a large localization base of large hydropower unit castings in China. In July, 2008, China Erzhong successfully cast the super large vertical roll frame Shagang 1450 mm vertical roll frame by using resin sand molding method. This vertical roll frame weighs 218 t per unit, up to 3 m, and is composed of more than 30 pieces of sand cores. The vertical roll frame is different from the ordinary frame. Because of its complex shape and geometric size, the production difficulty of the processes such as bed making, cavity production and core lowering is much more than the ordinary frame. In October, 2009, Erzhong successfully produced 4300 mm roughing mill stands for Southwest Aluminum by using alkaline phenolic resin sand process, with a total weight of 440 t of molten steel.
Due to the success of the alkaline phenolic resin sand process in the double application research, the promotion and application of this process in China has a good start, but it still needs domestic binder production units to strengthen the research of this new process, further improve the production level and quality stability of alkaline phenolic resin and supporting curing agent, and reach and exceed the foreign level as soon as possible. Equipment manufacturers need to conduct more detailed research on the specific characteristics and process requirements of alkaline phenolic resin and supporting curing agent in terms of equipment function configuration and material selection, so as to ensure the stability of equipment operation. Therefore, with the continuous improvement of the manufacturing level of raw and auxiliary materials and equipment related to the alkaline phenolic resin sand process in China, the process will be applied by more and more foundry manufacturers and will play an important role in improving the overall manufacturing level of steel castings in China.