As the largest heavy machinery manufacturer in the country, CITIC Heavy Industry Machinery Co., Ltd. provides various types of heavy equipment for users all over the world, including a speed reducer produced by a foreign company (see Figure 1). The gear box is welded . It is 7.1m high, 7m long, 5.72m wide and 320t in weight. It is the world's largest gearbox for reducer. The housing housing material is S355JR and has a thickness of 320mm. Using the existing special thick plate CNC flame cutting machine in the workshop, using the appropriate cutting parameters, the CNC cutting and cutting task was successfully completed. 1. Introduction of equipment and parts Using a CNC flame cutting machine manufactured by Messer Cutting & Welding (China) Co., Ltd., the maximum cutting workpiece thickness is up to 600mm (black metal), the gauge length is 6000mm, the rail length is 20 000mm, and the gas used is oxygen + propane. The cutting machine used for this cutting is shown in Figure 2. The part is a bearing housing, the size is 320mm × 1310mm × (5790 + 8) mm, the material is S355JR, and the length of the dimension is +8mm for the reserved welding shrinkage. S355JR is a low-alloy high-strength steel (European standard EN10025) with a yield strength of 355MPa, which is equivalent to the domestic Q345B. The blank of the workpiece is shown in Figure 3. 2. Preparation before cutting According to the drawings and process requirements, the steel plate needs to be ultrasonically inspected, and the flaw detection standard is EN10160-1999. The body defect is in the S3 level, and the edge defect is inspected at the E4 level. First, check the pipeline for leaks. If there is air leakage, it will not only cause waste of resources, but also affect the quality of cutting. In severe cases, it will cause flammable gas to collect and cause an explosion accident. Secondly, the accuracy of the cutting machine should be corrected. Flame cutting is a thermal process, and the effects of various complex factors in the cutting process can affect the accuracy of the cutting machine. In order to better ensure the quality of the cutting, before the cutting, we test the accuracy of the cutting machine, that is, draw a rectangle parallel to the guide rail on a whole steel plate, and program to make the cutting torch pass the same trajectory as the rectangular shape. Observe the deviation between the actual trajectory and the drawn rectangle. If the deviation is too large, the machine tool should be repaired by the professional until the requirements are met. Finally, the unevenness of the cutting platform is detected, corrected, and the distance between the platform support plates is appropriate to ensure that the support plate is in full contact with the workpiece. 3. Cutting jobs In the cutting process, the appropriate parameters should be selected. After many trial cuts, the specific parameters selected in the end are shown in the attached table. Since the production is in the winter, in order to prevent the occurrence of the cut crack, a two-cut method is adopted in order to sufficiently preheat the steel sheet. The first cut size is the outer contour size of the blank +30mm, and the blank blank is cut twice. In order to prevent the deformation of the workpiece, the cutting line is introduced by adding a "locking" method to prevent the workpiece from being separated from the steel plate during the cutting process, and a relative displacement is achieved, which achieves a good effect. Figure 4 shows the real scene cut, and Figure 5 shows the "lock". Cutting real scene 4. Conclusion Utilizing the existing special thick plate CNC flame cutting machine, selecting the appropriate cutting parameters, the CNC cutting task of ferrous metal with a thickness of 320mm was successfully completed, and accumulated relevant experience, which laid the foundation for the cutting of the extra thick plate. Drive Rivets,Drive Screw Rivet,Drive Rivets Lowes,Aluminum Drive Rivets Zhejiang XianChuang Auto Parts Co.,LTD , https://www.showstrong.com
reducer 
Extra thick plate CNC cutting machine 
Job blank 
"lock"