Medium thick carbon steel plate surface treatment technology

In the manufacturing industry of many professional mechanical equipment and large structural parts, the use of carbon steel plate is quite widespread, such as in the engineering, energy, mining machinery industry, many products use steel plate thickness of 6 ~ 20mm, some of these steel plates are not hollow plate material, and most of them are plate material with a hole rate of 30%, its specifications and dimensions vary by product and use. Small to the length and width of less than 100mm, large to 10m long, width 1 ~ 2m, size specifications vary. After the carbon steel plate is cut by plasma cutting or oxygen cutting, the cutting edge leaves different shapes of flash, slag and burr, these slag and burr must be removed, and the sharp edge must also be rounded.

Manual grinding

At present, most enterprises carry out artificial surface treatment of carbon steel plates after thermal cutting, mainly using hand tools such as hand grinding wheel, scraper, steel hammer for tapping and sweeping grinding. The disadvantages of this grinding method are: (1) quality problems, poor uniformity and thoroughness of grinding, affecting subsequent bending, spraying and other processes as well as the overall appearance and internal quality of the product. (2) Efficiency problem, the efficiency of manual grinding is difficult to grasp and statistics, completely depends on the working status and proficiency of employees, and the guarantee of efficiency is poor. (3) Environmental protection problems, knocking and grinding dust and slag splash, seriously polluting the atmospheric quality and environment inside and outside the working area. (4) Labor protection problems, air pollution is the main problem. In addition, the flying slag produced by grinding workpieces and the handling of heavy workpieces are major hidden dangers that cause personal injury accidents of employees.

Mechanical grinding

In recent years, some enterprises have also tried to use mechanical methods to deal with the slag and burr problem of the workpiece. Judging from the current market, there are roughly two solutions.

The first is the traditional dry single-side grinding program, through continuous feed grinding, the top of the work table is set up a number of grinding stations, namely grinding head, using a similar grinding medium to do continuous grinding of the workpiece. The grinding medium used is basically the abrasive belt and its variants of the grinding head (Figure 3). When grinding stubborn slag, the service life of the abrasive belt will be greatly reduced, and the life of 30 to 50 hours in deburring processing will be reduced to less than 10 hours once the slag removal treatment is done, which is not only the cost of consumables is large. The waste of time caused by the time and frequency of replacing consumables is even greater. In addition, under normal circumstances, the workpiece needs to be processed on both sides, using this single-side grinding scheme, after single-side grinding, the workpiece needs to be turned over and fed twice to complete the final processing requirements, which greatly reduces the processing efficiency.

The second is currently the most advanced dry double-sided processing technology, production line processing, through continuous feeding grinding, the workpiece is held by several groups of opposite upper and lower gripper rollers, through the body inside the symmetrical distribution of the grinding head respectively to remove slag, deburring, chamfering processing (Figure 4). The advantages of this processing method are commendable: first, the processing effect is thorough, clean, no residual slag and burr. Second, the surface treatment effect of a single piece is consistent with that of the whole batch of workpieces, which is an incomparable effect of manual processing. Third, high processing efficiency, the use of double-sided processing at the same time of advanced technology, than the traditional machining method to improve the efficiency of at least 60%, with the size of 400mm×100mm workpiece as an example, under the general processing requirements, the workbench width of 1500mm production line processing pieces per hour up to 1600, the production capacity is 40 to 50 times that of manual processing. It is 5 ~ 7 times that of traditional machining. Fourth, save a lot of human resources, production line type continuous processing, only equipped with 2 employees on the loading and unloading side can reach the capacity of 40 or 50 employees manual processing. Fifth, energy saving and environmental protection, the production line is equipped with an efficient dust removal system, the grinding dust is strictly controlled inside the body and is completely collected by the dust removal machine, and the dust gas can be filtered directly. However, such a production line is expensive, which is undoubtedly a small cost for the average small and medium-sized enterprises.

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It can be seen that the traditional mechanical grinding can not fundamentally meet the technical and batch requirements, and the advanced production process equipment fully meet the technical and batch requirements, but the high equipment investment can only shut out some enterprises that want to have a role but have limited strength.

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Multi-station dry single-side comprehensive treatment

In October 2018, at EUROBLECH, Europe's largest exhibition of sheet metal processing technology and equipment, we saw a new type of processing equipment - multi-station dry single-side integrated processing equipment (Figure 5). Soon after, this equipment with the latest processing concepts and technical features was introduced into the Chinese market. The basic design concept of the equipment is that the cutting-edge slag removal technology and burr, sharp edge grinding and blunt technology are cleverly integrated on a processing platform, so as to achieve a single feed and complete a variety of processing processes such as slag removal, burr removal, sharp edge chamfering, etc., to meet the original multiple processing requirements that can be completed by a production line.

The new equipment adopts a three-station processing layout. The first station adopts two steel hammer hammering belts made of special steel materials, and achieves the purpose of removing molten slag on the surface of the workpiece by horizontal tapping type. The second station adopts vertical abrasive belt surface grinding technology, which can remove the vertical burrs or clean and grind the workpiece surface through one-way and high-speed grinding on the workpiece surface. The third station adopts the combination of universal rotating roller grinding head to carry out full-cover three-dimensional grinding processing on the workpiece surface, to achieve the purpose of removing residual and secondary burrs, and to achieve uniform chamfering effect on the inner hole and outer edge of the workpiece surface. The three stations can be operated in parallel or controlled separately, and the processing parameters and processing mode can be independently regulated according to the processing requirements and different original states of the workpiece.

New processing technology and equipment will bring different effects, compared with the traditional grinding equipment, this new equipment cracked the process problem of slag removal; Compared with the advanced production line, although its single-sided processing mode makes it unable to match it in processing efficiency, the new processing technology and equipment set the three processing functions of the entire production line and grinding treatment technology in one, to achieve single-machine, multi-objective intensive processing, while greatly saving the area of the equipment. According to statistics, the new machine can reach 800 processing capacity per hour when processing 300mm×200mm workpieces, which is equivalent to the manual processing efficiency of 20 to 30 people in the same time. More importantly, the slag and burr are completely removed, the rounded corners are more uniform, the appearance quality of the product is greatly improved, and the procurement cost of the equipment is greatly reduced compared with the production line.