Analytical method for the remainder of the latest oil body frame shroud

(1) The diesel engine body should not be deformed by the influence of the heat source. Since the diesel engine body is made of large-scale integral steel castings, it is determined that it cannot use oxygen-acetylene operation to remove the residual roots. Of course, it does not mean that the diesel engine body can not touch the strong heat source such as electric welding and oxygen-acetylene, but it should have more strict technical requirements, such as the welding of the crack of the diesel engine body. That is to say, if an intense heat source such as electric welding or oxygen-acetylene is used, it is necessary to ensure that the diesel engine body is not affected by the heat source and is deformed.

(2) Reduce the preload. There are several ways to reduce the preload. For the larger diameter broken bolts, consider the following two ways:

Hammered. Through the hammering of the bolt head, the threaded fastener can be slightly deformed in contact with the friction surface, thereby reducing the friction pressure and reducing the pre-tightening force of the bolt. Drill the middle of the broken bolt. Because the cylinder head bolt of 16V280ZJA diesel engine is 18Cr2Ni4WA high-strength alloy steel processed by multiple processes, its hardness value is less than HRC35, and the hardness value of common twist drill edge is greater than HRC63, and the fracture surface of cylinder head bolt of 16V280ZJA diesel engine is more The flat diameter cut surface, therefore, drilling in the middle of the broken bolt is feasible. The drilling itself does not reduce the preload, but by drilling the middle of the broken bolt, it is possible to reduce the resistance of the broken bolt, especially the large diameter broken bolt. Combined with hammering after drilling, it will be practical to reduce the preload. (3) The process is simple, easy to operate, and can be implemented locally in the general maintenance section.

In order to improve work efficiency and facilitate drilling positioning, special drills can be made. Due to the high strength and large amount of work of the 16V280ZJA diesel engine cylinder head bolt, a proper amount of water should be injected into the counterbore to cool the drill bit, and the pistol drill must not be overheated. At the same time, during the drilling operation, the magnet is used to suck out the cuttings.

Drilling is the key point of this operation. For example, the 450W magnetic drill is more convenient and reliable, but the magnetic drill working platform must be configured. The drill chuck diameter must also be 24mm. The magnetic drill has the characteristics of low speed drilling position map, stable feed control, labor saving and convenience. It ensures that ordinary workers can successfully complete this assignment.

Drill bit breakage should be avoided as much as possible during the drilling process. Here is the worst and most prone to the problem of drilling and breaking the drill bit: you can use a blunt-head punch with a diameter of less than 5mm, and tap the twist hole of the 10mm drill bit to make the broken drill bit reverse. Easy to remove. (2) Processing spare parts. The upper part is machined into 16 pieces as shown. Spare part 1

It is machined from 14mm rebar of construction materials, and can also be processed with round steel of 45 or more in diameter of 12mm. At the same time, the spare part 1 must also prepare a spare part 2 of the same material of about 170 mm length. This step is a preparatory work that can be processed in the job room or before the job.

(3) Assemble spare parts. The 6 spare parts 1 machined by the machine tool are hammered into the drilled 6 holes, and the spare part 2 is inserted in the middle; then, 7 spare parts are welded and integrated into the upper part of the diesel engine body plane, and welded Insert one cylinder head (bolt) nut into the integral spare part to keep the upper end flush; finally, weld the nut to the spare part. This operation can basically ensure that the diesel engine body does not generate heat source deformation. (4) Take out the broken root. Before taking out, it is necessary to ensure that the welded one piece is naturally cooled to room temperature, and it is important not to cool it with water. If the cooling rate is too fast, the welded one piece will be hardened; and the welded one piece which is not completely cooled cannot meet the requirements of use. A manual or mechanical torque wrench can be used to remove the broken root. When removing, first use the hammer of about 4kg to hammer the upper end surface of the welded one piece 2030 times. The center of rotation of the welded one piece should not be too large as much as possible during the removal process.

Conclusion We have used this method to take out the broken bolt residual roots. The pistol drilled for 2 hours and welded for 10 minutes. After waiting for complete cooling, it takes less than 10 minutes to take out the residual root. When adding the cylinder head, it is a total of one. Working day. If the magnetic drill is used together with the drilling, the drilling time will be shortened to less than 05h, which will shorten the cylinder head bolt breakage of the 16V280ZJA diesel engine by nearly half a month, which greatly improves the utilization rate of the locomotive. If a DF8B locomotive is towed 4,500 tons per day and 800km is calculated, there will be 50 million tkm of cargo turnover in half a month. Practice has proved that this method is not only practical and effective, but also can bring significant economic benefits.