MT2V NC Profile Milling Machine is a CNC copy milling machine produced by OER LIKON Company imported by our factory. After installation and debugging in July 1997, it was put into use. Since January 1998, after the cold machine started the hydraulic lubrication system of the machine tool, the leakage failure at the lower end of the main shaft box began to appear. As the temperature dropped, the oil leakage became more and more serious, but the oil leakage began to gradually stop after the spindle started for 20 minutes. In this process, all the machine tools work normally and there are no alarms. MT2V CNC profile milling machine belongs to heavy-duty machine tool, its isotropic rail lubrication is completed by an independent rail automatic lubrication system: its hydraulic and spindle lubrication system is quite different from the FB2V and FB3V numerical control profile milling machines produced by Oricon. Hydraulic and spindle lubrication principles are shown in the figure. Hydraulic and spindle lubrication share a main fuel tank (using HM68 anti- friction hydraulic oil), the motor M1 drives the coaxial gear pump 1P, 2P rotation, 1P through the check valve 5, direct relief valve 6, the accumulator 8 to the machine tool The hydraulic system provides hydraulic oil with a pressure of 8MPa. Each solenoid valve controls the speed of the spindle, the clamping of the tool chuck, the loosening of the spindle head, and the relaxation of the Z-axis clamping. 2P provides lubricating oil to the headstock through the direct relief valve 2 and the chiller 1 , and then lubricates the bearings, gears, etc. in the headstock through the oil distribution pipes, and collects them into the return oil pool at the bottom of the headstock. The pump 3P is withdrawn into the main tank 3 . After the main power switch of the machine tool is closed, 3P is automatically started for 20s to withdraw the oil stored in the oil sump; the hydraulic lubricating system is started, 3P is started; the hydraulic lubricating system is stopped, 3P is delayed for 45s, and the remaining oil in the oil sump is withdrawn. . The chiller 1 detects the lubricating oil flowing through the interior of the chiller. When the lubricating oil temperature rises to a set temperature, the chiller is started and the lubricating oil is forcibly cooled. When the lubricating oil temperature is lower than the set oil temperature, the chiller is cooled. stop.
1. Refrigerator 2, 6. Directly controlled overflow valve 3. Main tank 4. Oil filter 5. Check valve 7. Manual shutoff valve
8. Accumulator 9. Hydraulic selector switch 10. Oil pressure gauge
MT2V hydraulic and spindle lubrication schematic analysis fault phenomenon and hydraulic lubrication principle, because it is a short time after the start of the hydraulic lubrication system in the low-temperature cooler oil leakage, and the machine moves normally, and without any alarm, can exclude high-pressure hydraulic system leakage problem. Fault scope should be in the spindle lubrication system, because the machine tool is still in the warranty period, the foreign maintenance personnel have to replace the oil pump 3P twice, but still not troubleshooting, with the spring temperature rise, the amount of oil leakage gradually reduced, The last failure completely disappeared. In the winter of 1998, as the temperature dropped, the fault reappeared. We have read the hydraulic lubrication part of the data, the data shows that when the hydraulic selector switch 9 is placed in the "2P" file, the oil pressure gauge 10 shows that the oil pressure should be 0.5 ~ 1MPa. At the scene, when the lowest ambient temperature in the factory is 6°C, the cold machine starts the hydraulic lubrication system of the machine. The oil temperature of the lubricant is 6°C. At this time, the oil pressure value of the "2P" gear is 1.8MPa. As the spindle operation time increases, the oil When the temperature rises, the oil pressure drops. When the oil temperature rises to the set temperature of 25°C, the cooler starts. The "2P" gear oil pressure value is 0.7MPa. After the oil pressure dropped to 1.2MPa, the amount of oil leakage began to decrease. After that, the fault gradually disappeared and the machine tool entered normal operation. The oil temperature periodically fluctuates between 18 and 26°C, and the oil pressure varies from 0.7 to 1.3 MPa with the oil temperature. Inter-periodic fluctuations, the relationship between oil temperature and oil pressure are shown in Table 1. It can be judged that the adjustment of the lubricant pressure during the installation and debugging of the machine in the summer also needs to be adjusted in the winter. Otherwise, the viscosity of the lubricant will increase when the ambient temperature decreases, and the return oil amount of the return pump will become smaller when the cold machine starts the hydraulic lubrication system. It appears that the amount of oil supplied to the spindle box lubricating oil is greater than the amount of return oil, causing oil spillage failure. According to the relationship between oil temperature and oil pressure, we understand that the “2P” oil pressure 0.5 to 1 MPa indicated in the hydraulic lubrication section description data is not generally understood as static adjustment to any value between 0.5 and 1 MPa, but should be understood as oil Pressure fluctuation with oil temperature between 0.5 ~ 1MPa (in any case not less than 0.5MPa). If the oil pressure adjustment value is too low, it will cause insufficient lubrication and cause equipment accidents. If the oil pressure adjustment value is too high, it will cause the headstock lubricant oil supply to exceed the oil return amount when the cold start system is started in winter, causing oil spillage failure. . Raise the oil pressure value. After adjustment, the relationship between the oil temperature and oil pressure during normal machine operation is shown in Table 2. When the cold start system is started, the oil pressure in the “2P” gear is 1.3 MPa. The principle that the hydraulic pressure is high and high is to be adjusted with the temperature constantly. In summer, adjusting the direct relief valve 2 has little effect on the lower limit of the oil pressure, especially when the spindle is running at a high speed, the oil temperature is maintained at 29 °C, the refrigerator no longer shuts down, the oil pressure is 0.45MPa, at this moment adjusts the direct control relief valve 2, has not been able to change the oil pressure value. Table 1 oil temperature oil pressure oil temperature (°C) 26 25 24 20 19 18 oil pressure
(105Pa) 8
(Cooler startup) 7
(Cooler start-up) 9.5 11 11.5 13 Table 2 Oil temperature after re-adjustment Relation between oil temperature (°C) 26 25 24 20 19 18 Oil pressure
(105Pa) 6
(Cooler start) 5.5
(Cooler start) 7.5 8.5 9 9.6 After adjustment, this failure has not occurred again in the past two years and the machine tool is operating normally.
