The heat of casting is an acute exothermic reaction caused by the inhalation of highly dispersed zinc oxide fumes produced during the smelting of copper. It has been reported that metal oxide smoke such as lead, tin, antimony, nickel, etc. can also cause this disease.
Definition of casting Casting - smelting metal, making a mold, pouring molten metal into a mold, and solidifying to obtain a blank of a metal part having a certain shape, size and performance
Casting is a process in which a metal is smelted into a liquid that meets certain requirements and poured into a mold, which is cooled and solidified and subjected to a treatment to obtain a casting having a predetermined shape, size and performance. The casting blank is nearly shaped, and it is free of machining or a small amount of processing, which reduces the cost and reduces the production time to some extent. Casting is one of the basic processes in the modern equipment manufacturing industry.
There are many types of castings for casting. According to the modeling method, it is customarily divided into 1 ordinary sand casting, also known as sand casting, sand turning, including wet sand type, dry sand type and chemical hardening sand type.
2Special casting, according to the modeling material, can be divided into special castings with natural minerals "target=_blank> mineral sandstone as the main modeling material (such as investment casting, clay casting, shell casting, negative pressure casting, solid casting) , ceramic casting, lost foam casting, etc.) and metal casting as the main casting material (such as metal casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.) two categories.
According to the molding process, it can be divided into 1. Gravity casting: sand casting, hard molding. The molten metal is poured into the cavity by gravity.
2. Pressure casting: low pressure casting, high pressure casting. The molten metal is instantaneously pressed into the casting cavity by an additional pressure.
The casting process usually includes 1 casting (a container for making liquid metal into a solid casting). The casting can be divided into sand type, metal type, ceramic type, mud type, graphite type, etc. according to the materials used, and can be divided into one-time according to the number of uses. Type, semi-permanent and permanent, the pros and cons of casting preparation are the main factors affecting the quality of castings;
2 melting and casting of cast metal, casting metal (casting alloy) mainly has various types of cast iron, cast steel and cast non-ferrous metals and alloys;
3 casting treatment and inspection, casting treatment includes removal of core and casting surface foreign matter, refining riser, burr and burr and other projections and heat treatment, shaping, anti-rust treatment and roughing. The casting process can be divided into three basic parts, namely casting metal preparation, mold preparation and casting processing. Cast metal refers to the metal material used for casting castings in casting production. It is an alloy composed mainly of a metal element and added with other metal or non-metal elements. It is customarily called cast alloy, mainly cast iron. Cast steel and cast non-ferrous alloys. Metal smelting is not only a simple melting process, but also a smelting process that allows the metal to be poured into the mold to meet the expected requirements in terms of temperature, chemical composition and purity. For this reason, various inspection tests for the purpose of controlling quality are carried out during the smelting process, and the liquid metal can be allowed to be poured after reaching various specified indexes. Sometimes, in order to achieve higher requirements, the molten metal is treated outside the furnace after being discharged, such as desulfurization, vacuum degassing, refining outside the furnace, gestation or deterioration treatment. Commonly used equipment for melting metal is cupola, electric arc furnace, induction furnace, electric resistance furnace, reverberatory furnace and the like.
The heat of casting heat casting is an acute exothermic reaction caused by inhalation of high-dispersion zinc oxide fumes generated during smelting of copper. It has been reported that metal oxide smoke such as lead, tin, antimony, nickel, etc. can also cause this disease. Preventing the escape of metal fumes is the fundamental way to prevent casting heat. In the operation of smelting, casting, etc., it is necessary to strengthen the airtightness, install a local exhaust dust removal equipment, and recover zinc oxide. Strengthening overall ventilation and wearing smoke masks can be used as an auxiliary measure.
Process Flow With the advancement of technology and the booming of the foundry industry, different casting methods have different mold preparation contents. For example, in the most widely used sand casting, the mold preparation includes two major tasks: preparation of the molding material, molding, and core making. Various raw materials used for molding and core making in sand casting, such as foundry sand, sand binder and other excipients, as well as molding sand, core sand, and coatings prepared by them are collectively referred to as modeling materials, and the task of molding materials preparation According to the requirements of the castings and the nature of the metal, the appropriate raw sand, binder and auxiliary materials are selected, and then they are mixed into a certain type of molding sand and core sand according to a certain ratio. Commonly used sand mixing equipment include a roller-type sand mixer, a counter-flow sand mixer and a continuous sand mixer. The latter is designed for mixed chemical self-hardening sand, continuous mixing, and quick mixing.
Modeling and core making are based on the requirements of the casting process, based on the determination of the modeling method and the preparation of the modeling materials. The accuracy of the casting and the economics of the entire production process depend mainly on this process. In many modern foundry workshops, styling and core making are mechanized or automated. Commonly used sand-type molding core equipments include high, medium and low pressure molding machines, air punching molding machines, boxless injection molding machines, cold core box core machines, hot core box core machines, and coated sand core machines.
After the castings are taken out of the cast-cooled mold, the castings with gates, risers, metal burrs, and crevices are also adhered to the sand, so they must be cleaned. Equipment for performing such work includes a sander, a shot blasting machine, a pouring riser, and the like. The sand falling of sand castings is a process with poor working conditions. Therefore, when selecting the modeling method, it should be considered to create convenient conditions for the falling sand cleaning. Some castings are subject to special post-processing requirements such as heat treatment, shaping, anti-rust treatment, roughing, etc.
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