Abstract: The spindle grinding wheel of the cylindrical grinding machine has oil leakage, and the skeleton oil seal is frequently replaced to cause the spindle to be injured. In this paper, the fault is explored and repaired, and the two schemes are compared and analyzed. Fault phenomenon In September 2007, our company purchased a cylindrical grinding machine model MC1363/4000H from Shanghai Machine Tool Plant. The grinding wheel of the grinding machine adopts the dynamic and static pressure bearing structure, and the hydraulic oil enters the oil chamber of the bearing sleeve from the oil inlet pipe, so that a static pressure bearing is formed between the bearing sleeve and the main shaft, and the left end of the bearing sleeve adopts a skeleton oil seal to the main shaft and the static The pressure bearing is hydraulically sealed. Due to the high-speed operation of the spindle for a long time, the skeleton oil seal for sealing the hydrostatic bearing hydraulic oil causes the main shaft (the contact portion with the skeleton oil seal) to be ground and grinds several deep grooves. In this way, the hydraulic oil will leak out from the “injured†part of the main shaft during normal operation, causing oil leakage and messy scenes. 2. Failure analysis and solution The equipment is used frequently and has a long service life. In addition to improper maintenance, the skeleton oil seal of the sealed hydrostatic bearing is frequently replaced once the grinding wheel spindle oil leaks, so that the main shaft in contact with the skeleton oil seal is severely ground. Now even if the skeleton oil seal is replaced, the problem of the oil leakage of the main shaft cannot be effectively prevented, and the equipment can not be used if it is completely stopped. Here are two maintenance options: (1) Option 1: Add a gasket on the inner side of the left end of the frame oil seal and the left end cover of the main shaft (see Figure 1), so that the place where the deep groove is ground by the oil seal is blocked or staggered by the gasket, because the left end cover of the spindle The assembly position is limited, the thickness of the gasket should not be too thick, but it must be ensured that the position of the deep groove can be avoided. Therefore, a special gasket is calculated and designed, as shown in Fig. 2. Due to the limited space, the outer diameter of the skeleton oil seal is slightly larger and can be slightly treated to allow the oil seal to enter the shallow groove at the left end of the bearing sleeve (φ 160 mm). Figure 1 Schematic diagram of the spindle assembly of the grinding wheel frame 1. Spindle 2. Grinding wheel 3. New gasket 4. Skeleton oil seal 5. Bearing 6. Housing This not only ensures the seal but also avoids a lot of maintenance work, and saves a lot of money. However, this program also has shortcomings. We know that although this solution is good, it can't solve the problem fundamentally: once the spindle is ground again, the space cannot be increased indefinitely due to the small space, and the solution loses its meaning. (2) Option 2: Disassemble the grinding wheel spindle, weld the deep groove of the main shaft grinding, grind after surfacing, or spray after disassembly. The fault is sprayed and the secondary processing is carried out after the spraying. The requirements for precision and coaxiality tolerance are also very strict during the grinding process. After the spindle is repaired, it can be installed and restored. The maintenance process of the program is complicated and the construction period is long, but the geometric accuracy of the grinding wheel spindle can be guaranteed after recovery. This wheel frame spindle is different from the common cylindrical grinding machine of the MQ1350 type. The grinding wheel spindle of the MQ1350 is mounted in two front and rear sliding bearings. Each bearing consists of three fan-shaped bearing bushes, each of which is 120°, each supported by a ball screw. During work, it was found that the quality of the grinding was affected by improper bearing clearance and could be readjusted. The spindle of the MC1363 cylindrical grinding machine is supported by dynamic and static pressure bearings, and the spindle clearance cannot be mechanically adjusted. The grinding wheel spindle bearing lubrication uses a membrane feedback device PS, and a separate fuel tank for the grinding wheel spindle bearing lubrication, which is provided by the gear pump pressure, the pressure controller controls the regulation system pressure. When the system pressure is >1.4MPa, the electrical signal indicates that the lubrication system is normal, and the grinding wheel spindle can be started. Dismantling the spindle, the assembly recovery process is more complicated, the bearing sleeve clearance and the film feedback device ensure normal, because the bearing clearance is slightly or slightly inadvertent, it will cause the bearing sleeve to "catch the shaft", and even the phenomenon of "heating fever" . Therefore, the program has relatively high technical requirements for maintenance personnel. The factors such as spindle bearing, spindle recovery and dynamic and static pressure differential lubrication during assembly recovery are particularly critical. 3. Maintenance effect This maintenance uses Option 2, because the previous maintenance is based on Option 1. The MC1363 cylindrical grinding machine spindle is used normally after repairing. The effect is very good. The spindle does not leak oil during operation, and the operation is stable. The accuracy of the radial and axial runout of the spindle is within 0.005mm. After the production and use certification in recent years, the most obvious one is not only good, but also quick to repair and simple in process, but it has its own limitations. The maintenance method of the second scheme is the most conservative and most reliable. After all, the worn part of the main shaft can be recovered, but the maintenance cost of this scheme is large and the maintenance period is long. In the maintenance process, it is necessary to determine which solution is most appropriate according to the actual situation. Stainless Steel Pipe Fitting, Brass Pipe Fitting, Elbow Pipe Fitting, Water Pipe Fitting ZHEJIANG KINGSIR VALVE CO., LTD. , https://www.cn-kingsir.com
Figure 2 Adding a gasket