The flame cutting method of the ultra-long single-sided rack provided by the present invention includes the following steps A to D:
 A. Preheat the whole steel plate to be cut to 200~300℃;
 B. Fix the preheated steel plate on the cutting platform;
 C. Measure the temperature of the steel plate, and start cutting when the temperature of the steel plate is between 100 and 150 ℃. During cutting, use two cutting torches to cut two tooth edges along two cutting tracks on the steel plate at the same time. The distance between the two tooth edges is equal to a single tooth. The width of the rack plus the slit compensation width, a double-sided rack is obtained after cutting;
 D. Cut the double-sided rack obtained in step C into two parts along the cutting track 2 to obtain two single-sided racks to complete the rack cutting.
 In step A, the overall preheating may adopt a method of placing the steel plate in an annealing furnace for heating. Compared with the local preheating in the prior art, the overall preheating operation is simple and convenient, and existing equipment can be used without adding heating equipment, which effectively saves costs. More importantly, the overall preheating can heat the entire steel plate uniformly, and the overall cutting performance will change, avoiding the sudden change of temperature in some areas of the steel plate caused by local heating, which will lead to changes in the physical and chemical properties of the material, and the resulting defects of reduced processing accuracy. .
 The overall preheating temperature can be 200~300℃, the above preheating temperature is used to preheat the steel plate, so that the steel plate will be naturally cooled to the best cutting temperature of the steel plate within 100~150℃ during the subsequent fixing process (about 2 hours) , To facilitate subsequent cutting processing. When the preheating temperature is higher than 300℃, the steel plate will have large and difficult to control thermal expansion and deformation, which will affect the cutting accuracy; when the preheating temperature is lower than 200℃, the temperature of the steel plate may be reduced to Lower than the optimal cutting temperature, the cutting performance of the steel plate is greatly reduced. If the steel plate waits for a long time to be cut, it can also be covered with insulation material to maintain the temperature. The thermal insulation material is preferably aluminum silicate fiber, which has the characteristics of high temperature resistance, low thermal conductivity, light bulk density, good elasticity, and non-toxicity, and is especially suitable for heat preservation of metal plates.
 In step B, the length of the long edge of the cutting platform beyond the long edge of the steel plate is less than 0.5m, and the length of the short edge of the cutting platform beyond the short edge of the steel plate is less than 0.5m. The size of the cutting platform is determined according to the size of the steel plate to be cut. To facilitate fixing the steel plate, the size of the cutting platform is usually larger than the steel plate. However, a too large cutting platform is not conducive to the fixation of the steel plate, because the steel plate has a tendency to move to both sides under the cutting action. If the space on both sides is too large, the steel plate will have a greater displacement and affect the cutting accuracy. Therefore, the present invention sets the size of the cutting platform so that the length of each edge beyond the corresponding edge of the steel plate is less than 0.5 m, which can effectively limit the displacement of the steel plate and improve the cutting accuracy.
 In step B, the steel plate on the cutting platform is preferably fixed by intermittent welding, and the distance between two adjacent welding points is less than 2 meters. The welding fixing method is reliable, which can ensure that the steel plate does not have any slight displacement during the cutting process, and ensures the cutting accuracy. After the steel plate is cut, the remaining steel material can be cut and separated from the cutting platform, and the cutting platform can be reused.
 In step C, the temperature of the steel plate is measured, which can be measured by an infrared thermometer. When keeping the steel plate at the best cutting temperature of 100-150℃, the steel plate is in the best cutting state, which can effectively improve the cutting quality and cutting efficiency. When the temperature exceeds 150°C, the steel plate will form larger thermal expansion and deformation due to the increase in temperature, and the excessive cold shrinkage of the tooth profile during the cooling process of the processed rack will greatly change the tooth profile The profile, size, etc. affect the accuracy of the rack. When the temperature is lower than 100°C, the cutting performance of the steel plate cannot be improved well, which affects the cutting quality and cutting efficiency.
 Step C and Step D cutting processing, such as figure 1 As shown, the first step is to simultaneously cut two tooth edges along two cutting tracks 1 to obtain a double-sided rack, and then cut straight along the cutting track 2 to obtain two single-sided racks.
 When cutting single-sided racks in the prior art, due to the different linear shapes and lengths of the curved and straight sides of the cutting, the uneven heating of the two sides of the rack causes the deformation of the steel plate. In addition, the rack used for the offshore platform is an ultra-long rack. Up to 5 meters or more, the cutting deformation gradually accumulates and eventually forms a larger deformation, which greatly reduces the cutting accuracy of the rack. However, the present invention adopts the method of cutting two tooth edges at the same time, and then cutting into two single-sided racks from the middle. When cutting two tooth edges at the same time, since the line type and length of the two tooth edges are exactly the same, the heat is evenly heated during cutting. It eliminates the deformation caused by uneven heating, thereby significantly improving the cutting accuracy of the single-sided rack, so that the processed rack can fully meet the requirements of the offshore platform, and the cutting efficiency is significantly improved.
 In step C, the slit compensation width is related to the thickness of the cutting steel plate, the size of the cutting nozzle, etc., and can be set to 5-7mm.
 In step C and step D, the cutting torch can be a jet-suction torch, and the cutting gas can be oxygen-propane. Because the oxygen propane cutting flame temperature is lower and the cutting deformation is small, the rack deformation can be further controlled and the cutting accuracy can be improved. The low heat of the oxygen-propane cutting gas can ensure that the upper surface of the steel plate will not melt and affect the cutting quality.
 In steps C and D, the cutting oxygen pressure is determined according to the thickness of the cut steel plate. The greater the thickness, the greater the oxygen pressure. Preferably, the oxygen pressure is adjusted so that the cutting flame exceeds 1/6 of the thickness of the steel plate, or the oxygen pressure is adjusted to 0.75-0.9 MPA.
 In step C and step D, the cutting speed can be 130-170 mm/min. The cutting speed directly affects the stability of the cutting process and the quality of the cutting section, while a too fast cutting speed will cause quality defects such as depressions and slagging on the cutting section. Therefore, the present invention comprehensively considers the cutting gas, the performance parameters of the cutting nozzle, and the steel plate material. And thickness and other factors, determine the cutting speed is 130 ~ 170mm/min.
 The flame cutting method of the ultra-long single-sided rack provided by the present invention further includes step E: after the rack cutting is finished, after the rack is cooled to room temperature, the rack parts are hoisted and taken out. The rigidity of the rack is low when the rack is at a high temperature, and large deformation is likely to occur during the hoisting process, which affects the accuracy of the rack. Therefore, it is preferable to wait for the rack to cool to room temperature before hoisting and taking out.