On the whole, the academic research in the field of foundry in China is not backward, and many research results rank in the international advanced level, but less is converted into real productivity. The high level of domestic casting production technology is limited to a few backbone enterprises, the overall technical level of the industry is backward, the casting quality is low, the material and energy consumption is high, the economic efficiency is poor, the working conditions are poor, and the pollution is serious. The specific performance is that the appearance is still processed by hand or simple machinery; There is a large gap between the socialization, specialization and commercialization of the production and supply of raw and auxiliary casting materials, and it is far from meeting the needs of the development of new processes and technologies in terms of variety quality. The production level and quality of casting alloy materials are low; Backward production management; Process design is more based on personal experience, less computer technology application; Casting technology and equipment and other basic conditions are poor; The proportion of manual operation in the production process is high, and the technical quality of on-site workers is low. Only a small number of large automobile and internal combustion engine group foundries adopt advanced molding core process, most of the casting enterprises still use jolt-pressure molding machines or even manual molding, core to paulownia oil, fat and clay binder sand. Most investment casting plants mainly make water glass shells; Low pressure casting can only produce non-iron or cast iron small and medium-sized parts, can not produce cast steel parts; EPC technology is used to stably put into production only exhaust pipe, shell and other castings, productivity is less than 30 type/hour, casting dimensional accuracy and surface roughness level is low; Although a more complete casting industry standard system has been built, most enterprises passively implement standards, enterprise standards are lower than GB (national standard) and ISO (international standard), and some enterprises reject rate as high as 30%; Quality and market awareness is not strong, only a small number of professional casting enterprises through the ISO9000 certification. The research on quality management combined with the characteristics of foundry enterprises is very weak.
In recent years, some advanced melting equipment has been developed and promoted, and the temperature and comprehensive quality of liquid metal have been improved, such as the application of external hot air cupola, but a small number of them use only 1% of cast coke. Some casting non-ferrous alloy plants still use fuel oil, coke crucible furnace and other backward melting technology. The cupola-electric furnace dual process is only applied in a few mass production lines. A small number of large and medium-sized electric arc furnaces use ultra-high power (600-700kVA/t) technology.
The introduction of refining equipment and technology such as AOD and VOD has improved the intrinsic quality of high-grade alloy cast steel. Ultra-low carbon high-strength martensitic stainless steel for important projects, using refining technology to improve the purity of liquid steel, performance improvement. 0Cr16Ni5Mo, Cr13Ni5Mo cast martensitic stainless steel on the basis of maintaining the original toughness, the yield ratio has improved from 0.70-0.75 to 0.85-0.90, the strength has improved by 30%-60%, and the hardness has improved by 20%-50%.
Widely used in domestic rich rare earth resources, such as rare earth magnesium treated ductile iron in automobiles, diesel engines and other products; Rare earth medium carbon low alloy cast steel and rare earth heat resistant steel have been applied in machinery and metallurgical equipment. The domestic series of inoculants, nodulators and vermiculators were initially formed, which promoted the quality improvement of cast iron.
High strength, high elastic modulus gray cast iron is used for machine tool castings, and the application of high strength thin-wall gray cast iron casting technology makes the sectional hardness difference of the cylinder block and cylinder head castings with the thinest wall thickness of 4-6mm less than HB30, and the organization is uniform and dense. Laser hardening of gray cast iron surface is used in production. Application of artificial intelligence technology in guessing the properties of gray cast iron. Vermicular graphite cast iron has been applied in automobile exhaust pipe and high-horsepower diesel engine cylinder head, and the service life of automobile exhaust pipe has been improved by 4 to 5 times. Vanadium titanium wear-resistant cast iron is applied on machine guide rail, cylinder liner and piston ring, and its life is improved by 1-2 times. High, medium and low chromium wear-resistant cast iron is used on grinding ball, lining plate, impurity pump and bimetal composite roll, and its life is improved. The application of filtration technology in the production line of high-strength thin-wall castings such as cylinder block and cylinder head can reduce the defects of slag inclusion and porosity and improve the internal quality of castings.
Domestic horizontal continuous casting production line into the market, can produce Φ30-250mm round and corresponding size of square, rectangular or shaped section of gray cast iron and ductile cast iron profiles. Compared with the sand mold, the performance has improved by 1-2 grades, the utilization rate of liquid iron has improved to more than 95%, energy saving 30%, material saving 30-50%, and the pass rate of blank processing has reached more than 95%.
Cast iron pipe industry introduced 23 sets of Φ1000mm below the medium-sized ductile iron pipe centrifugal casting equipment, of which 20 sets are currently in normal production. In addition, we have produced Φ2600mm cast pipe with our self-developed ductile iron pipe centrifugal casting equipment, of which the diameter of the normal mass production cast pipe reaches 2200mm, and the diameter of the cast pipe centrifugal casting equipment developed by our country has reached 3000mm.
Progress has been made in the research of metal matrix composites, and there are achievements in the research of short fiber, external particle reinforcement and in-situ particle reinforcement, but few industrial applications have been realized.
The backbone founds in some key industries have adopted direct-reading spectrometers and thermal analyzers, effectively controlled the liquid metal composition before the furnace, and adopted ultrasonic detection methods to control the quality of castings.
The strengthening of environmental law enforcement has forced the foundry industry to pay attention to environmental protection technology. Shenyang Foundry Research Institute has developed the technology of double-layer air supply cupola with large row distance and dehumidification air supply of cupola. China has built the first production base of cast coke to form a batch scale. Casting dust toxic treatment, sewage purification, waste slag utilization and other achievements have been achieved, and a variety of casting environmental protection equipment has been developed (such as vibration shakeout machine dust cover, mobile vacuum cleaner, dust purification device, sewage purification recycling system, casting old sand dry and wet regeneration technology and equipment, casting waste sand slag waste plastic composite material technology and equipment, etc.).
Commercial CAE software is available. Some large and medium-sized casting enterprises began to use computer technology in melting to control liquid metal composition, temperature and productivity. Chengdu University of Science and Technology has developed an online control system for sand treatment, Tsinghua University has developed computer-aided sand control system software, and Huazhong University of Science and Technology has successfully developed commercial casting CAE software.
The Internet of casting industry has developed rapidly, and some online e-commerce activities of casting enterprises are active, such as some casting mold factories have realized remote design and remote manufacturing.
Although the research of foundry expert system started late, it made rapid progress. The expert system of molding sand quality control, casting defect analysis, self-hardening sand quality analysis, die casting process parameter design and defect diagnosis have been introduced successively. Manipulators and robots are used in shakeout, casting cleaning, die casting and investment casting production.
Changshu Hongqiao Cast Steel Co., Ltd. mainly produces various specifications of carbon steel, high, middle and low alloy steel, stainless steel, heat-resistant steel, high manganese steel, high chromium cast iron. For petroleum, chemical industry, metallurgy, mining machinery, coal mining machinery, wind power, nuclear power, Marine and other industries to provide high-quality steel casting, and export abroad. Which steel casting is of good quality? Cost-effective? Changshu Hongqiao cast steel.