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  • Product Name: Plasma continuous edge cutting technology and application
  • Added time: 2018-07-18

China North Locomotive Company Qiqihar Track Equipment Co., Ltd. (161002) Wang Liwen Li Xinyi Yuchao plasma cutting technology, with laser cutting, water jet cutting, CNC turret punching are flexible sheet metal manufacturing technology, but plasma cutting due to its efficiency High, low operating costs, more mature technology, and widely used in the sheet metal manufacturing industry. As a manufacturing technology, how to improve efficiency and reduce costs is the key to measuring the pros and cons of the technology under the premise of meeting the quality requirements. The common process of plasma cutting is single-piece closed cutting, in addition to continuous cutting, bridge cutting and co-edge cutting, etc., compared with single-piece closed cutting can improve efficiency and material utilization, but often due to material state, programming skills, equipment accuracy For other reasons, it is easy to cause waste and defective products, and the use effect is not satisfactory. Through many years of plasma cutting practice, the author has explored the continuous edge cutting process and achieved good technical and economic benefits.
1 Production efficiency and material cost analysis in the conventional cutting process The production efficiency mainly refers to the workload completed per unit time.
This refers to the unit time to complete a complete cutting program. Includes loading and unloading time, gun time, free time during cutting, and plasma cutting time. During plasma cutting, since the table area is large, the loading and unloading process can be performed simultaneously, so the loading and unloading time can be ignored.
When the gun and the cutting travel are empty, the plasma walking speed is above 6000mm/min, and the stroke is relatively short. It can be seen that the gun time and the idle time have little effect on the cutting efficiency, and the actual cutting time is determined by the cutting efficiency. Actual cutting time = cutting distance (workpiece profile length) / cutting speed (when the plate thickness is constant, the cutting speed is relatively fixed), so the cutting efficiency is affected by the cutting distance.
Material costs mainly depend on material utilization. The main factors affecting the material utilization rate are the scrap boundary value and the part spacing. The determining factor is the part spacing. The spacing of the parts is set. The conventional cutting method is based on the material of the material, the thickness of the plate and the size of the slit on the cutting tool. The cutting time is generally set to about 10 mm, which is already the minimum value. If the distance between the parts is too close, the adjacent workpiece will be cut during the cutting process or the scraping gun will occur due to the uneven part of the sheet.
According to the above analysis, the most direct and effective way to improve production efficiency is to reduce the cutting distance; the most direct and effective way to save material cost and improve the utilization rate of the plate is to reduce the distance between parts.
2 continuous edge cutting process by edge cutting is the adjacent two workpieces without leaving the part spacing, sharing a common edge, so that there is no part gap distance in the cutting, saving material, but also reducing the cutting length. Based on the above analysis results, breaking through the traditional cutting mode, the use of edge cutting process is the best choice to improve efficiency and reduce cutting costs.
2.1 The basic mode of the edge cutting and the applicable range The basic method of continuous cutting by the edge is as shown. It is suitable for one or several parts to share a contour, and the new contour after sharing, can achieve reasonable layout during the layout optimization process.
2.2 By-edge cutting process control points 2.2.1 Deformation control Plasma cutting selects the cutting direction and the arcing position to control the deformation. The principle is as follows: When the quality of the workpiece is much smaller than the remaining sheet on the base metal, the workpiece to be cut should be ensured as much as possible. The last cutting edge (the arcing point) should be finally separated from the base metal plate. If it is separated from the base metal prematurely, during the cutting process, since the mass of the material separated prematurely from the base material is far less than the mass of the base material, the thermal deformation stress will be separated in advance. Some materials have a certain displacement relative to the machine platform. At this time, the displacement part of the material has not been cut into the workpiece, which makes it difficult to ensure the process size of the workpiece.
When the quality of the workpiece is equal to the quality of the remaining sheet material on the base metal, both the sheet and the workpiece may move during the cutting process. In this case, the cutting should be carried out according to the principle of the final masterbatch, but corresponding measures should be taken to fix the workpiece. For example, increase the weight or fix the workpiece by other means.
When the workpiece quality is much larger than the residual material quality, the material will be displaced after cutting, and generally does not affect the size of the cutting workpiece.
When the game is cut by the parent, the deformation control is the most difficult point for the success of the cutting. Since the cutting part is divided into two or more cuts, the material around the part is in a semi-open state, and the selection of the cutting direction and the arcing position is much more complicated than the normal cutting.
2.2.2 Treatment of joints at adjacent parts When cutting by the edge, the two parts share one side, which is equivalent to a common size, so that one size changes and the other size changes accordingly, especially in the setting cut. When the seam is compensated, it is easy to cause dimensional deviation of the part.
Some parts cannot be cut in one arc, but two or more arcs cut the enclosed workpiece, which is likely to cause cutting defects at the seam.
2.2.3 Cutting program programming Because of the programming software, it is not possible to automatically handle common parts or complex edge cutting in complex situations. Therefore, a certain amount of subsequent processing is required in the programming of the borrowing side.
2.3 The necessary conditions for ensuring the cutting quality The working platform requires the working platform (supporting rack) to have a smooth surface, a slight slag hanging, and a reasonable spacing and spacing of the supporting rack. The flatness is not greater than the flatness requirement of the sheet (flatness 2rrnn/m2).
The unevenness and intrinsic stress of the material required for the flatness of the sheet is very large. The plate must be leveled before cutting, fully releasing the internal stress of the plate, generally flatness 矣 2mm/m2. Requirements for operation 1 Before cutting, carefully check whether the condition of the sheet and working platform meets the process requirements, check the cutting parameter setting. It is reasonable; 2 It is necessary to check the replacement electrode and nozzle in time to ensure the cutting quality and keep the cutting value in the normal range; 3 If the workpiece is long, the workpiece should be perpendicular to the bracket beam after cutting to avoid cutting. The workpiece is tilted and the scraper is generated. When the operator is not allowed to leave the console during the cutting, the machine should be observed. If the sheet or workpiece is deformed by the internal stress of the material, the displacement or other abnormal conditions are dealt with immediately. It is strictly forbidden to start off work.
3 By edge cutting application example The lower cover is a component for railway wagons. It was originally cut by conventional methods, and now it is cut by edge.
The normal cutting process scheme of the lower cover is Q150 steel plate is 3150mmx3150mmx6mm, the effective cutting distance of single block is 2777mm, the material edge value is 15mm, the part spacing is 20mm. One plate can be cut 16 pieces, the plate utilization rate is 69%. Cutting layout As shown in the figure, the edge of the material is as shown.
The continuous edge-cutting scheme improves the utilization rate of the single-piece effective cutting distance from 69% to 89% of the conventional cutting method. By cutting the cutting sleeve as shown, the material edge is as shown. The lower cover plate cut by edge is fully in line with the quality requirements, the production efficiency is increased by 38%, and the utilization rate of the plate is increased by 20%. It also means that the consumption and loss of cutting auxiliary materials are greatly reduced.
4 Conclusion By edge cutting technology can significantly improve production efficiency and raw material utilization rate, the conventional cutting process method, material utilization is difficult to exceed 75%, and the continuous edge cutting process can generally reach more than 80%, the benefits are significant. It has broad application prospects in the field of sheet metal cutting.
Technical management work.

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