Discussion on spraying technology of the hottest t

2022-08-04
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In the 21st century, the carton packaging industry is developing rapidly in China. The fierce market competition makes carton enterprises pay more attention to product quality and enterprise cost. As the heart part of the production line, the corrugated roller plays an important role in carton quality and economic benefits. The traditional corrugated roller has become increasingly unable to meet its needs. In recent years, foreign high-quality corrugating rollers have successively entered the domestic market, among which tungsten carbide corrugating roller is the leading one. Tungsten carbide corrugating roller is a special process that uses thermal spraying technology to melt and spray tungsten carbide alloy powder onto the tooth surface of corrugating roller to form tungsten carbide coating. The following will specifically introduce the application of thermal spraying technology, the spraying process of tungsten carbide corrugated roll, the elements to ensure the quality of tungsten carbide corrugated roll, and the advantages of tungsten carbide corrugated roll (compared with traditional ordinary corrugated roll)

thermal spraying technology the application of

thermal spraying is a process that uses a heat source to melt the spraying material, atomizes the molten droplets by the power of the heat source itself or an external high-pressure air flow, and sprays them to the workpiece surface at a certain speed to form a coating. The functions of wear resistance, heat resistance, corrosion resistance, electromagnetic interference resistance and decoration under various industrial and mining conditions are strengthened

There are many kinds of thermal spraying for the furnace roll in the high temperature section of CAPL in the steel plant, among which the coating with the best quality should be "supersonic flame spraying". This spraying method has been successfully used for many years in China's aerospace, steel, petrochemical, oil field, textile, shipbuilding and other industries, greatly improving the performance of the workpiece. Applying this technology to the corrugating roll, due to the particularity of the use conditions and tooth profile of the corrugating roll, it is difficult to develop

tungsten carbide corrugating roller spraying process

simplified preliminary treatment is different from the traditional corrugating roller, which needs to be formulated according to the spraying conditions. The tooth profile processing needs to consider the spraying allowance to complete the forming on the CNC corrugating roller grinder. The quality of surface cleaning and coarsening is the basis for obtaining excellent coatings. The cleaning work increases the adhesion of the coatings. The uniform edge and angle state of coarsening is conducive to the mechanical locking effect. The increase of surface area also further improves the bonding strength of the coatings for medium and high-end stone plastic flooring, such as new SPC flooring and LVT flooring

due to the extremely high surface hardness of the sprayed tungsten carbide layer, it is impossible to grind it with a general grinding wheel. It must be completed with a special polishing process to ensure a precise ridge shape

elements to prove the quality of tungsten carbide corrugating roller

spraying technology: since the tooth surface of the corrugating roller is a continuously fluctuating curved surface, and can not be directly used after Jan spraying, it needs to be grinded. Therefore, the uniformity and bonding strength of spraying are different from other workpieces, so the requirements are higher, and the spraying technology is more complex

spraying equipment: there are many kinds of spraying equipment, and selecting excellent equipment is the key to get a good coating. The temperature, speed, porosity, oxide, bonding speed and deposition rate of the spray melting flame are the main basis to reflect the equipment performance. The speed of the flame flow determines the bonding strength. The oxide bottom ensures the hardness of tungsten carbide. The porosity is the density, high energy and enhanced wear resistance. At present, the JP wanl produced by Praxair Surface Technology Co., Ltd. of the United States has also made suggestions and progress in terms of packaging methods and product design. The 5000 HP/HVOF spraying system is an internationally recognized equipment that can obtain the best coating. Its combustion design is based on the rocket engine. It uses high-pressure and large flow of oxygen and aviation kerosene to burn in the combustion chamber with special structure, producing a high pressure of up to 150psl, The flame flow speed is up to 2200m/s, ensuring that all indicators reach the ideal state. The defect is that the operation cost is high. K1 kerosene is 30L/h, oxygen is 2300 cubic feet/h, and the high-speed flame flow is accelerated, which is easy to damage the damaged parts

tungsten carbide powder: there are many tungsten carbide alloy powder manufacturers. Compared with domestic, imported tungsten carbide powder has a more mature and stable process, and can obtain dense, high hardness and good wear resistance coating, but the price is expensive. The average size of raw material WC particles has a great impact on the performance of the sprayed coating. The composition of wcl2 powder is WC/12%co (cobalt based tungsten carbide). In order to improve the wear resistance of the coating, larger WC particles are used at higher cost. The wear resistance of 3.5um is 4 times that of 0.2hm. At the same time, the closer the wcl2 powder particles are to the ideal spherical shape, the better the fluidity. China's technology is slightly backward, and the depth and density of the particles are more optimized

advantages of tungsten carbide corrugating roller (compared with ordinary corrugating roller)

improve the quality of paperboard

because in consideration of wear, the tooth profile design of ordinary corrugating roller is difficult to achieve the best in some parameters (such as top circle and tooth height); Because the tungsten carbide corrugating roller is not worn, it is optimized in the tooth shape design to achieve the ideal paperboard state

the tooth height and top circle of the ordinary corrugating roller change greatly, and the quality of the paperboard is unstable. The gap between the core paper and the glue coating roller expands with the wear in the middle of the corrugating roller. At the same time, the increase of the top circle after wear leads to too much glue, making the paperboard soft and easy to bend; Due to wear resistance, the tungsten carbide corrugating roller can ensure that the tooth height and top circle are always the same and can be used for a long time. The quality of paperboard is flat and stable

save production cost

■ reduce the use of core paper. The corrugating rate of the corrugated design is small, and generally 2% ~ 8% of the core paper is less used, which is very important to the carton enterprises. Because the ordinary corrugating rollers wear fast, the factors such as higher corrugated height and larger top circle have to be considered in the original design to ensure a certain service life. The tungsten carbide corrugating roller does not have this problem because of wear resistance

■ reduce waste. The middle of the ordinary corrugating roller is excessively worn and becomes concave, and it is easy to produce waste paper when reproducing wide width cardboard, because both ends will be pressed gb1499.2 ⑵ 007/xg1-2009 steel for reinforced concrete Part 2: hot rolled ribbed steel bars No. 1 amendment to the national standard; Broken or no paste in the middle (degumming and blistering), at this time, you have to grind both ends of the roll in order to walk the wide cardboard and maintain the service life of the roll. Tungsten carbide corrugating roller has no concave phenomenon in its long service life

■ increase life. The service life of tungsten carbide roll is generally 3-6 times longer than that of ordinary roll

■ reduce the amount of glue. The original design tooth circle is small, and there is no wear top circle becoming larger, and there is no uneven glue amount between the two ends and the middle caused by intermediate wear

■ reduce damage to other units. Such as glue roll, pressure roll, etc., the concave of ordinary corrugating roll is destructive to the adjustment and use of other parts

■ the replacement times of corrugating rollers are reduced

■ the most important thing is that the corrugating height of tungsten carbide corrugating roller is almost unchanged throughout its operating life. The wear of corrugated top is the main reason for the poor quality of paperboard and the replacement of corrugated roller. (end)

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