Source: China Environmental News
The picture shows Ding Wenjiang (second from left), academician of the Chinese Academy of Engineering, leading an expert evaluation committee to inspect castings produced using new carbon-free clay green sand casting technology at Gaomi Zhicheng Machinery Co., Ltd.
The picture shows workers in the production workshop of Weifang Yuchuan Machinery Co., Ltd. using the molding machine and new carbon-free clay green sand to make casting shapes.
walked into Yuchuan Machinery Co., Ltd. and Zhicheng Machinery Co., Ltd., Weifang City, Shandong Province. Amidst the roaring machinery, we could see the sand molds on the production line trolley moving forward at a constant speed. There was almost no dust on the ground in the entire workshop, and there was also a smell. There is no peculiar smell. Workers are methodically using khaki molding sand to mold shapes on the molding machine. Next to the production line are cast diesel engine cylinder heads, water jacket exhaust pipes, textile machine head castings and other products. This is what the reporter saw when he followed the new carbon-free clay green sand casting technology expert evaluation committee on an on-site inspection of the company a few days ago.
China Foundry Association recently organized a scientific and technological achievements evaluation meeting on "Application Research on New Carbon-free Clay Green Sand Casting Technology" in Weifang City, Shandong Province. The evaluation committee composed of well-known domestic experts such as Li Peigen and Ding Wenjiang, academicians of the Chinese Academy of Engineering, and Zhang Libo, president of the China Foundry Association, listened to the work report, technical report and other reports of the project team after the on-site inspection of the company, and reviewed the applications provided by the project unit. Certification and other scientific and technological achievement evaluation materials.
After detailed questioning and discussion, the expert evaluation committee unanimously agreed to pass the scientific and technological achievements evaluation of the project, believing that the new carbon-free clay green sand casting technology is an original technical achievement that has reached the international leading level and cracked the foundry industry coal powder The clay green sand casting technology has long faced the global problem of pollution. It has very important application value and can provide strong technical support for the transformation, upgrading and green development of the foundry industry.
Traditional sand casting technology faces three major problems
As we all know, the foundry industry is the foundation of the equipment manufacturing industry and is closely related to people's lives and industrial production. Everything from daily necessities to high-end equipment is inseparable from casting. Among them, castings produced by sand casting method account for more than 80% of the total castings. Molding sand is the main modeling material in casting production and plays an important role in casting production.
The reporter learned that the existing foundry sand mainly includes three categories: coal powder clay green sand, water glass sand, resin sand . At present, most foundries at home and abroad are using coal powder clay green sand. This type of sand adds organic matter such as coal powder and carbonaceous additives to the clay green sand. It is mainly used to resist sand sticking and sand inclusion. However, due to the The casting quality and environmental pollution problems caused by the inherent defects of coal powder clay green sand have never been solved.
Water glass sand is made of quartz sand, water glass and additives. The resulting sand mold can be chemically hardened by blowing CO2, or can be hardened by heating or hardened by itself under the action of a hardener. This kind of molding sand does not contain toxic substances and is more environmentally friendly. However, sodium silicate sand has insurmountable shortcomings such as difficulty in sand falling out, difficulty in regenerating old sand, and serious sand sticking, making it impossible to fully promote it.
Resin sand is mixed with quartz sand, resin and hardener. Commonly used resins include furan resin, resol phenolic resin and urethane resin. The sand mold made with this kind of sand has high strength, accurate size, good disintegration property and low energy consumption. However, a large amount of toxic gases are produced during the production process, resulting in large emissions and high costs.
"Molding sand casting technology has three major global problems: high pollution, high energy consumption, and low casting quality. The casting process will produce exhaust gas pollution, dust pollution, and solid waste pollution. Severe dust and gas pollution in the foundry workshop leads to a very poor working environment for workers. The dust and gases discharged outside the workshop are also one of the important sources of haze," said Zhu Shigen, a professor at Donghua University. The resin sand and sodium silicate sand currently used in production can only be used once. Although the pulverized coal clay green sand can be partially reused, the total emissions are very large, and the solid waste pollution is very serious.
In addition, the foundry industry is a large energy consumer in the machinery industry. Its energy consumption accounts for about 45% of the total energy consumption in the machinery industry, of which the consumption of pulverized coal is considerable.Castings produced by traditional casting technology often have many pores, sand inclusions, and sand washing, resulting in problems such as uneven product surfaces, heavy cleaning workload, and large machining allowances, seriously reducing production efficiency and causing a high scrap rate. No less than that, of which the scrap rate caused by molding sand accounts for about half.
School-enterprise cooperation to develop new carbon-free clay green sand
In recent years, with the promulgation of legal documents such as the new Environmental Protection Law, the Air Pollution Prevention and Control Law, and the Three-Year Action Plan to Win the Blue Sky Defense War, the emission of pollutants has Standards are also constantly rising. As a traditional high-energy-consuming and high-pollution industry, the foundry industry emits the most solid waste and air pollutants during its production process. How to reduce environmental pollution while ensuring the quality of castings is an important issue faced by traditional casting companies.
In order to solve the problems of pulverized coal clay green sand, Donghua University, Shandong Xuanhe New Material Technology Co., Ltd., and Yiwu Yunxi New Material Technology Co., Ltd. have developed a new type of carbon-free clay green sand over several years, using pure inorganic materials. The raw materials do not contain any pulverized coal and any pulverized coal substitutes, and do not contain any carbonaceous materials and organic materials.
"The new carbon-free clay green sand has the characteristics of green environmental protection, low carbon energy saving, circular economy, high-quality castings, etc. It breaks through the anti-sticking sand and sand inclusion mechanism of traditional coal powder and other organic matter, and masters the effective effect of the interface between molding sand and metal. The control principle has achieved a substantial transformation from an accidental experimental phenomenon to a replicable and repeatable technology, forming a new technology of pure inorganic anti-sand, which is the first of its kind at home and abroad and has successfully applied for a national patent for "new carbon-free clay." Said Zhu Shigen, professor of Donghua University, the inventor of green sand technology.
It is understood that the new carbon-free clay green sand is earthy yellow in color, and its raw materials are all non-toxic inorganic substances. Its conventional indicators are equivalent to those of coal powder clay sand. Its normal temperature wet pressure strength, fluidity and compaction rate are adjustable, and it has good air permeability. , high hot-wet tensile strength, which can ensure basic modeling operations and pouring requirements.
In addition, the new carbon-free clay green sand has high high-temperature hot-pressing strength, small high-temperature thermal expansion rate, and better recyclability. No waste gas is produced during the casting process, and the small amount of waste sand produced does not have any toxicity, and can even be used to cultivate land. The surface roughness and dimensional accuracy of castings produced using this molding sand are improved, subsequent machining is easier, and energy consumption in processing and cleaning is reduced.
New sand production test feedback is good
Laboratory research has laid the foundation for the actual production and application of new carbon-free clay green sand. However, the production conditions in the foundry industry vary widely. Whether it is the size, shape and material of the parts, the molding method used and the degree of automation, or factors such as the molten iron pouring temperature, the height of the pressure head and the pouring speed, all will put forward different requirements for the molding sand. Whether the new carbon-free clay green sand casting technology can withstand the test of actual production conditions requires further actual production testing.
Starting in 2014, new carbon-free clay green sand began large-scale production and application testing in foundries in Zhejiang, Jiangsu, Fujian, Shandong and other places. The products produced include automobile castings, valve castings, engine block and cylinder head castings, fire pipe fittings, motor casings, water pump castings, road accessories and other products. Casting materials include ductile iron, gray iron, aluminum alloy, etc. Molding methods include manual molding, shock molding machine molding, vertical parting extrusion molding, etc.
After testing, the new carbon-free clay green sand is fully suitable for the production of castings of various materials and sizes such as gray iron, ductile iron, and non-ferrous iron. No toxic waste gas is produced during the pouring process and no air pollution is caused. The floating dust in the workshop has been greatly reduced and the air quality has been significantly improved. A small amount of waste sand scrapped during the casting process is non-toxic and harmless, has a color similar to soil, and has good compatibility with the environment. There is less sand adhering to the surface of the production castings, and there are fewer sand inclusion and sand washing defects. Porosity defects are rarely found in the castings. The quality of the castings is improved, and the product yield can be increased by 3% to 5%.
In September this year, Weifang Deere Casting Co., Ltd. cooperated with Shandong Xuanhe New Material Technology Co., Ltd. to use new carbon-free clay green sand casting technology to conduct production tests of Steyr engine six-cylinder block castings."This kind of cylinder water chamber is composed of a water jacket core, which has strict requirements on the casting process and is a very difficult casting to produce. To facilitate comparison, the same pressure, pouring temperature and speed as ordinary molding sand are used in the production process. After comparison, it was found that the new sand has better air permeability and resistance to sand adhesion and sand inclusion than clay sand, and the casting quality and accuracy fully meet the requirements," said Zhao Fahai, chief engineer of Weifang Dier Casting Co., Ltd.
Since December 2017, Gaomi Zhicheng Machinery Co., Ltd. has purchased a total of 503 tons of new carbon-free clay green sand for vertical parting injection molding casting production. It has been used for 10 months to produce and export various agricultural machinery accessories. More than 2,500 tons of castings. “After using the new molding sand, the black visual pollution of traditional green mold sand is eliminated, no toxic waste gas is produced during the casting process, dust floating in the workshop is greatly reduced, and the air quality is significantly improved; waste sand emissions are reduced, and the produced castings do not stick to the sand. , easy to clean, improved yield, and relatively reduced casting costs," said Sun Shensheng, general manager of the company.
In addition, Zhu Shigen also led the project team to compare the pollutants emitted by different molding sands during the production process. The data shows that the hourly average concentration increments of particulate matter (PM2.5, PM10, PM100), formaldehyde, carbon dioxide and after the pulverized coal green sand was poured exceeded the provisions of GBZ2.1-2007 "Occupational Exposure Limits to Hazardous Factors in the Workplace" The hourly average concentration increments of sulfur dioxide and nitrogen dioxide exceeded the limits specified in GB3095-2012 "Ambient Air Quality Standard". After the new carbon-free clay green sand was poured, the particulate matter (PM2.5, PM10, PM100), formaldehyde, nitrogen dioxide, and carbon dioxide did not exceed the limits specified in GB2.1-2007 "Occupational Exposure Limits to Hazardous Factors in the Workplace" , Carbon monoxide and sulfur dioxide did not exceed the limits specified in GB3095-2012 "Ambient Air Quality Standard".
"Casting itself is a traditional industry of material recycling. What we have to do is how to produce castings in a more environmentally friendly and energy-saving way. The emergence of new carbon-free clay green sand gives us more confidence to invest in it as soon as possible. production, and do our part to protect the ecological environment," said Yan Xuelia, director of the casting department of Qinwei (Tianjin) Industrial Co., Ltd. of Qinmeida International Holdings Co., Ltd.
Technological breakthroughs help industry transformation and upgrading
In recent years, the conversion of old and new kinetic energy has become a national strategy, and the driving force for the conversion of old and new kinetic energy lies in innovation. The research and development of new carbon-free clay green sand is of great significance in changing the situation of high pollution and high energy consumption in the foundry industry and promoting the transformation and upgrading of the industry.
reporters saw from the evaluation opinions formed by the expert evaluation committee that the project team led by Zhu Shigen systematically researched and developed a new type of carbon-free clay green sand for the first time at home and abroad, which has excellent conventional casting performance and does not contain carbonaceous materials such as coal powder and Organic materials save energy, have low emissions of waste gas, dust and solid waste, have good recyclability, reduce sand consumption and reduce costs. They are a new breakthrough in the development of green sand casting technology. Relevant technical standards should be formulated as soon as possible to further expand the scale of application.
Lu Xinmin, director of the foundry branch of the Chinese Mechanical Engineering Society, said: "Whether it is application effect or originality, the emergence of new carbon-free clay green sand casting technology plays an important role in the foundry industry across the country, especially in Under the background that it will take the country three years to win the battle to defend the blue sky, this technology will have more opportunities to be promoted."
Ren Xingwu, Chairman of Weichai Power (Weifang) Casting and Forging Co., Ltd. said, Weichai Group . We have been looking for more environmentally friendly and energy-saving casting technologies and solutions. The new carbon-free clay green sand casting technology is a major breakthrough in the traditional coal powder clay sand technology. We will actively contact and continue to pay attention to this product. When conditions are mature, Consider applying it to Weichai's production line.
Liu Wei, general manager of Weifang Yuchuan Machinery Co., Ltd., said at the evaluation meeting: "As an advanced unit of green casting in the country, we are the first to use new carbon-free clay green sand casting technology to set a leading example for the transformation, upgrading and green development of local foundry companies. effect."
" new carbon-free clay green sand casting technology was unveiled in Weifang City as a major original achievement leading technological progress in the foundry industry. It received unanimous praise from experts, fully proving the advancement and forward-looking nature of this technology. As a local government, we will go all out to support this technology and support the conversion of old and new kinetic energy, the transformation and application of new technologies, new achievements, and new models. " Zhang Longjiang, Mayor of Fangzi District, Weifang City, said.
Wu Zhou, Chairman of Shandong Xuanhe New Materials Technology Co., Ltd., said that this expert evaluation will be of great significance to the company, as it will vigorously promote the products in the foundry industry in the later period and help the foundry industry realize the new and old goals. The foundation has been laid for kinetic energy conversion and green development
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