At present, CNC cutting machines have begun to be widely used in industrial enterprises, and the types of cutting are also diverse, such as flame cutting, wire cutting, plasma cutting, etc., but due to the impact of resources, cost and other factors, the most widely used is still Flame cutting machine.
In the actual cutting process, when flame cutting is used, it often occurs that the workpiece is deformed during the cutting process. Here, we do a detailed analysis for users to solve the problem of how to effectively avoid thermal deformation in the flame cutting process.
I. Manual intervention in the process of programming:
1. The thermal deformation of the workpiece is due to the uneven heating and cooling of the steel plate, and the effect of the internal stress of the material causes the workpiece to be bent or displaced to varying degrees. Therefore, the workpiece that is easily deformed in the programming nesting is as much as possible. It is placed in the middle of the whole steel plate, and a larger gap is reserved between the workpiece and the workpiece. In this way, the workpiece is in the middle of the master during the cutting process, and the tension generated by cutting thermal deformation can be effectively offset.
2. A reasonable cutting sequence is also one of the effective conditions for preventing cutting deformation. The following principles should be followed when sorting workpieces: inside first, then outside, small first, then large, round first, rear first, then simple. First inside, then outside, that is, when there are more inner holes, first cut the middle hole and gradually proceed outward, so that the heat generated by the cutting is transmitted from the inside to the outside regularly; first small and then large, that is, if the inner hole of a workpiece is large For an hour, you should try to cut the small hole first, and then the large hole. The heat generated by the small hole is relatively small, and the impact on the workpiece is small; after the first round, the heat generated by cutting the round hole is radiated outward. Transmission, the internal stress of the steel plate is relatively balanced, but the square hole is different. The thermal stress generated by cutting the square hole has a greater impact on the work piece; first, it is simplified, that is, the complex hole is cut first, and then the simple shape is cut. Bore.
3. If you encounter a narrow bar workpiece, you can manually increase 1-2mm in the length direction during the programming process, because if deformation occurs, the length of the narrow bar workpiece will be reduced due to deformation and distortion, and it will not meet the actual cutting size requirements. The increase in length can effectively make up for the loss of length caused by deformation.
4. The choice of the location of the perforation point is also an important factor affecting the deformation. The perforation of each workpiece should be selected as far as possible (that is, penetration at the corners of the workpiece), because if it is penetrated at the half-waist of the workpiece, the workpiece will not be closed due to deformation and distortion after cutting, followed by penetration at half-waist The perforation point is easy to burn the workpiece, resulting in defective products and waste products.
Second, the prevention method in the cutting process:
1. "Bridge crossing" cutting: For very long shaped parts, the "bridge crossing" cutting method can be used. During the cutting process, a few "bridges" of about 10-30mm are artificially reserved. In this way, the workpiece and the mother body are cut during cutting. Always connected to reduce the deformation of the workpiece. After the workpiece is cooled, the "crossing bridge" is cut off.
2. When the size of the workpiece is close to the size of the steel plate (such as when using scrap material) and when cutting large workpieces, as the material edge is separated from the workpiece, thermal deformation causes the material edge to quickly bend. Due to the reaction force of the table, the workpiece will be displaced. Resulting in dimensional deviation. If during the cutting process, the material edge is cut in sections by a manual cutting saw in time, and it will be removed before the material edge affects the workpiece, which will effectively prevent the size caused by the deformation of the material edge. deviation.
3. It is very easy to generate thermal deformation when cutting thin steel plates. A better control method is to spray compressed air or water at the cutting opening to speed up the heat dissipation during the cutting process, thereby reducing the thermal deformation of the workpiece. In addition, for steel plates with a thickness of less than 5mm, a laminated plate cutting method can be used, that is, multiple steel plates are stacked and clamped and held by a clamp. The thickness of the steel plate is generally less than 10mm. The surface of each plate is required to be clean. The oxygen cutting method can obtain relatively satisfactory cutting quality.
4. Wedge positioning. The basic manifestation of thermal deformation is the distortion of the workpiece. Therefore, during the cutting process, a suitable position is continuously selected in the wedge to continuously drive the wedge to force the workpiece to be positioned, which can effectively reduce the distortion caused by thermal deformation.
5. Use the correct cutting process specifications. Different cutting process specifications are used, and the size of the workpiece is not the same. Therefore, it is necessary to strictly implement the process specification and adjust the error in time to control the workpiece size within the allowable tolerance range.
In summary, there are many reasons that affect the cutting deformation of steel plates. Therefore, different measures need to be taken according to different situations, starting from programming to cutting and blanking at the same time to maximize the control of cutting thermal deformation.
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