Improvement of vibration polishing process for abrasive belt of marine diesel engine piston rod
The piston rod is one of the main moving parts of the marine diesel engine. When the diesel engine is working, the piston rod is subjected to the cyclical gas force and inertial force, and the processing quality will directly affect the performance of the diesel engine. The piston rod belongs to the long shaft type parts. Both ends are flat flanges. The shaft is a cylindrical hollow body. The outer surface is hardened and hardened, and has high tensile strength and rigidity, as shown in Figure 1. In order to ensure the performance of the diesel engine during navigation, the shape and surface roughness requirements of the piston rod surface are high. Conventional grinding wheel grinding methods have been difficult to meet the requirements of piston rod quality and production efficiency, as well as ship owners' increasingly strict requirements for marine products. Therefore, we use surface finishing as a research direction to improve the quality and efficiency of piston rod processing and to continuously meet the requirements of shipowners. According to the characteristics of the long shaft parts of the piston rod, combined with the practical experience of our factory for processing piston rods for many years, we found that the grinding belt grinding and polishing auxiliary grinding wheel rough grinding process is effective. Problem analysis After quenching the surface of the piston rod, the hardness is relatively high, and the Vickers hardness is generally 420-620 HV20 according to the relevant specifications. Grinding is the most commonly used method of processing, but the grinding efficiency is low, and the material cost and machine maintenance cost are high. Take the Wärtsilä 7RT-flex82T piston rod processed by our factory as an example (see Figure 1), its weight is 2 590kg, the total length is 4 237mm, the quenching area is 3 691mm, the diameter is 324f7mm, the cylindricity is within 0.02mm, the surface The roughness value requires Ra = 0.4 μm, and the surface allowance before quenching is generally f0.6 to f0.8 mm. In order to meet the requirements, the domestic M1380B×50 cylindrical grinding wheel grinding and grinding process requires a working time of about 20 hours, but the surface appearance after the finished product is difficult to satisfy the shipowner. The belt grinding and polishing auxiliary grinding wheel rough grinding process scheme, the final product can not only meet the requirements of the pattern, but also the surface strips and vibration lines left by the grinding wheel grinding, the total working time is about 18h, in which the grinding wheel coarse grinding It takes about 15 hours to work and the grinding time of the belt requires about 3 hours. The belt can be vibrated and polished by the company's existing domestic HT125×50 heavy-duty horizontal lathe, and the comprehensive working time of the lathe is only half of the cylindrical grinding machine. In this way, through the improvement of the process, although a processing process has been added, we have simultaneously improved the quality and efficiency of the piston rod processing, and saved the cost, and it is particularly important to meet the strict requirements of the shipowner for the appearance of the marine product. 2. Process improvement The belt vibration polishing system can be used on a horizontal lathe, with less one-time investment and greater flexibility. During work, the abrasive belt is unidirectionally conveyed at a constant speed and polished with the high-speed wide vibration of the polishing head. The abrasive belt is not reused, which avoids the inconsistency of the first and last polishing effects of the workpiece during the general polishing, and can effectively remove the grinding wheel. The vibration fringes and wobble strips caused by grinding have better surface consistency after processing, and the contrast effect is shown in Fig. 2. Compared with the traditional grinding wheel to improve the surface roughness, the belt vibration vibration polishing process has high processing efficiency and easy control of quality. The use of abrasive belt vibration polishing instead of grinding wheel grinding and auxiliary grinding wheel rough grinding process is very suitable for the production status of our company's piston rod surface finishing. ...... For more information, please download the attachment or view Metalworking (Cold Processing), Issue 23, 2013: Flange Fittings are widely used for connecting between the heavy duty industrial equipments and machines and hoses.Our flange fittings including SAE standard flange from 3000Psi to 9000Psi,with the shapes straight,45 degree and 90 degree.The flange fittings material is high quality number 45 carbon steel ,which can assure the fittings safty and stability.The Carbon Steel Flange Fittings are also called SAE Flange Fittings,Flange 9000Psi Fittings,3000Psi Flanges ,6000Psi flanges,Flange Clamps,Interlock flange fittings. 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Figure 1 Marine diesel engine piston rod