Treatment of metal surface by sanding and derusting in Dalian

Nowadays, the development of heavy industry is inseparable from profile sand blasting and derusting equipment. Profile sand blasting and derusting equipment plays an increasingly important role in heavy industry, especially in construction industry. The development of profile sand blasting and derusting equipment has played an important role in the development of a series of heavy industries such as iron and steel casting industry. Its quality has also been paid more and more attention by some people in the heavy industry. The quality of profile sand blasting and derusting equipment provided by Qingdao Qinggong machinery is very high. To a certain extent, it can contribute to the development of many fields in heavy industry, make the development of industry better and better, and promote the development of national economy.

Dalian sanding and derusting uses compressed air as power to form a high-speed jet beam to spray spraying materials (garnet sand, copper ore sand, quartz sand, emery, iron sand and Hainan sand) to the workpiece surface to be treated at high speed, so as to change the appearance or shape of the outer surface of the workpiece surface. Pretreatment stage of sand blasting process: it refers to the treatment that should be carried out on the surface of the workpiece before spraying and plating protective layer. Sand blasting derusting uses compressed air as power to form a high-speed jet beam to spray spraying materials (garnet sand, copper ore, quartz sand, emery, iron sand and Hainan sand) to the workpiece surface to be treated at high speed, so as to change the appearance or shape of the outer surface of the workpiece surface. Pretreatment stage of sand blasting process: it refers to the treatment that should be carried out on the surface of the workpiece before spraying and plating protective layer.

Sand blasting rust removal control is mainly reflected in the following aspects.

Ⅰ. Preliminary control: before sand blasting, the corrosion grade of metal structure substrate surface shall be evaluated according to the provisions of corrosion grade and derusting grade of steel surface before coating. Carefully check, remove welding slag, spatter and other attachments, clean the surface grease and soluble dirt, and properly deal with useless welding bodies or connections.

Ⅱ. Tool control: during sand blasting operation, the air pressure of the air compressor is 6.0 × 105～6.5 × 105Pa, pressure variation of 0.5 × 105～1.0 × 105Pa。 Generally, the air pressure of sand bucket is 4.5 × 105～5.5 × 105Pa, not less than 4.0 × 105Pa。 Before sand blasting, check whether the manufacturer of pressure vessel holds the production license issued by relevant departments, whether the protective tools, safety belt (rope) and oxygen supply device worn by sandblasting workers are safe and reliable, and the wear of nozzle. When the diameter of orifice increases by 25%, replace the nozzle.

Ⅲ. Abrasive control: the sand used in sand blasting and derusting process shall be hard, angular, dry (water content < 2%) and free of soil and other impurities; Quartz sand is better, and coarse river sand can also be used; At the same time, factors such as sand transportation conditions, unit price and recovery capacity shall be considered; The sand particle size should be 0.5 ~ 1.5mm. It must be dried before screening and stored in the shed and indoor. The screen hole size is: 40 ~ 48 holes / cm2 (particle size 1.2mm) for coarse screen and 372 ~ 476 holes / cm2 (particle size 0.3mm) for fine screen. After the rust removal scheme is determined, the abrasives can be river sand, quartz sand or a mixture of the two. In the danger removal and reinforcement of Gangnan Reservoir, through the comparison of pre spraying, the effect of rust removal is good when quartz sand and river sand are mixed at 1 ∶ 1.

At present, the derusting of large holds and hull in the repair process of many shipbuilding enterprises in China is basically the way of copper ore derusting, which will produce large dust floating into the atmosphere and cause serious pollution to the atmosphere; At the same time, the waste sand produced by it will also pollute the water quality. In order to change this traditional way of sanding and derusting, developed countries have long begun to study and apply alternative methods of traditional derusting.