Tell you what are the main points of the spindle machining center?
Tell you what are the main points of the spindle machining center?
The machining center was developed from CNC milling machines. The biggest difference with the CNC milling machine is that the machining center has the ability to automatically exchange machining tools. By installing different tools on the tool magazine, the machining tool on the spindle can be changed in one clamping by the automatic tool changer to realize various machining. Features.
Maintenance analysis and troubleshooting methods for common faults of electric spindles:
1, electric spindle heating
(1) The pre-tightening force of the spindle bearing is too large, causing the friction to be too large when the spindle rotates, causing the spindle temperature to rise sharply.
Troubleshooting method: It can be eliminated by re-adjusting the spindle bearing preload.
(2) If the spindle bearing is damaged or damaged, the friction will be too large when the spindle rotates, causing the spindle temperature to rise sharply.
Troubleshooting: Can be removed by replacing the new bearing.
(3) The lubricating oil of the spindle is dirty or has impurities, which will also cause excessive resistance when the spindle rotates, causing the spindle temperature to rise.
Troubleshooting method: By cleaning the spindle box and re-changing the oil to eliminate it.
(4) If the spindle bearing is depleted of grease or too much grease, it will also cause the resistance and friction of the spindle to rotate too much, causing the spindle temperature to rise.
Troubleshooting: Eliminate by reapplying grease.
2. The electric spindle stops when the cutting is strong.
(1) The transmission belt connected to the spindle motor and the spindle is too loose, causing the spindle transmission torque to be too small. When the powerful cutting is insufficient, the spindle torque is insufficient, and an alarm is generated. The CNC machine tool automatically stops.
Troubleshooting method: Eliminate by adjusting the tension of the spindle drive belt.
(2) The surface of the transmission belt connected to the main shaft motor and the main shaft has oil, which causes the transmission belt to slip when the main shaft is driven. When the main shaft torque is insufficient during the strong cutting, an alarm is generated and the CNC machine tool automatically stops.
Troubleshooting: Eliminate by cleaning with gasoline or alcohol and wiping it clean.
(3) The transmission belt connected to the spindle motor and the main shaft fails to be used for a long time, causing the spindle motor torque to be unable to be transmitted. When the powerful cutting, the spindle torque is insufficient, an alarm is generated, and the CNC machine tool automatically stops.
Troubleshooting: Eliminate by replacing the new spindle drive belt.
(4) The clutch and coupling in the spindle drive mechanism are too loose or worn, which causes the torque transmission error of the spindle motor to be too large, and the spindle vibration is strong during strong cutting. The alarm is generated and the CNC machine automatically stops.
Troubleshooting: Eliminate by adjusting or replacing the clutch or coupling.
3. The noise is too large when the electric spindle is working.
(1) The dynamic balance of the spindle components is poor, causing excessive vibration when the spindle rotates, causing operational noise.
Troubleshooting method: Professionals of the machine tool manufacturer are required to re-check and debug all the spindle components.
(2) The spindle transmission gear wears, so that the gear meshing clearance is too large, and the impact vibration is too large when the spindle rotates, causing working noise.
Troubleshooting: Professionals from machine tool manufacturers are required to inspect, repair or replace the spindle drive gears.
(3) The main shaft support bearing is pulled or damaged, so that the main shaft rotation gap is too large, and the impact and vibration are too large during the rotation, causing working noise.
Troubleshooting: Professionals from machine tool manufacturers are required to inspect, repair or replace bearings.
(4) The spindle drive belt is loose or worn, causing excessive friction when the spindle rotates, causing working noise.
Troubleshooting: Eliminate by adjusting or replacing the drive belt.
4, the tool can not be clamped
(1) The displacement of the disc spring is too small, so that the spindle gripper and the clamping device cannot reach the correct position, and the cutter cannot be clamped.
Troubleshooting: Eliminate by adjusting the length of the disc spring stroke.
(2) The spring collet is damaged, so that the spindle clamping device cannot clamp the tool.
Troubleshooting: Eliminate by replacing the new spring collet.
(3) The disc spring fails, so that the spindle gripper and the clamping device cannot move to the correct position, and the cutter cannot be clamped.
Troubleshooting: Eliminate by replacing the new disc spring.
(4) The shank pull-up nail is too long, and it hits the spindle gripping knife and clamping device so that it cannot move to the correct position, and the tool cannot be clamped.
Troubleshooting: Eliminate by adjusting or replacing the pull studs and installing them correctly.
5, the tool can not be loosened after clamping
(1) The pressure and stroke of the loose knife hydraulic cylinder are not enough.
Troubleshooting: Eliminate by adjusting the hydraulic pressure and the position of the travel switch.
(2) The disc spring is too tightly pressed so that the spindle clamp cannot move completely to the correct position and the tool cannot be loosened.
Troubleshooting method: By adjusting the nut on the disc spring, reduce the amount of spring compression to eliminate.
Analysis and treatment process of severe heat generation when the electric spindle rotates at high speed:
The problem of heat generation and temperature rise during the operation of the electric spindle is always the focus of research. There are two main heat sources inside the electric spindle unit: one is the spindle bearing and the other is the built-in main motor.
The most prominent problem with the electric spindle unit is the heating of the built-in main motor. Since the main motor is next to the spindle bearing, if the heat dissipation problem of the main motor is not solved well, it will affect the reliability of the machine tool. The main solution is to use a circulating cooling structure, which is divided into two types: external circulation and internal circulation. The cooling medium can be water or oil, so that the motor and the front and rear bearings can be sufficiently cooled.
The spindle bearing is the core support of the electric spindle and one of the main heat sources of the electric spindle. Most of the current high-speed electric spindles use angular contact ceramic ball bearings. Because ceramic ball bearings have the following characteristics:
1Because the ball is light in weight, the centrifugal force is small and the dynamic friction torque is small.
2 The thermal expansion caused by the temperature rise is small, and the pre-tightening force of the bearing is stabilized.
3 The amount of elastic deformation is small, the rigidity is high, and the life is long. Due to the high operating speed of the electric spindle, there are strict requirements on the dynamic and thermal performance of the spindle bearing. Reasonable pre-tightening, good and sufficient lubrication is a necessary condition to ensure the normal operation of the spindle.
Lubricating with oil mist, the atomizing generator inlet pressure is 0.25~0.3MPa, 20# turbine oil is used, and the oil droplet speed is controlled at 80~100 drops/min. Lubricating oil mist also takes a lot of heat while fully lubricating the bearings. The distribution of lubricants in the front and rear bearings is a very important issue and must be strictly controlled. The cross section of the air inlet is larger than the sum of the cross sections of the front and rear fuel injection ports, and the exhaust gas should be smooth. The injection angle of each injection hole is at an angle of 15o with the axis, so that the oil mist is directly injected into the bearing working area.
The main points of the electric spindle repair process:
1. Measure static and dynamic radial runout and lift clearance and axial yaw according to the damage of the electric spindle.
2. Remove the electric spindle with a special tool. Clean and measure rotor swing and wear.
3. Optional bearings. The uniformity error of the inner hole and the outer diameter of each set of bearings is ≤0.002~0.003mm, and the gap between the inner hole and the inner hole of the sleeve is maintained at 0.004~0.008mm; the gap with the main shaft is maintained at 0.0025~0.005mm. The electric spindle maintenance looks for the machine. In actual operation, it is best to push the bearing into the sleeve with the thumb of both hands. Too tight will cause deformation of the outer ring of the bearing, the temperature rise of the bearing is too high, and too loose will reduce the rigidity of the grinding head.
4, the cleaning of the bearing is an important part of ensuring the normal operation and service life of the bearing. Do not blow the bearing with compressed air, because the hard particles in the compressed air will pull the raceway.
5, tapered bearings or angular contact ball bearings must pay attention to the bearing installation direction, otherwise the rotation accuracy requirements. Special tools are used throughout the assembly process to eliminate assembly errors and ensure assembly quality.
6. When the inner hole of the sleeve is deformed, the roundness is out of tolerance, or the bearing is too loose, the local plating method can be used for compensation and grinding to the requirements. This method can also be used at the journal.
7. The end faces of the round nut and oil seal cover on the electric spindle are in close contact with the end faces of the inner and outer rings of the bearing respectively. Therefore, the perpendicularity of the threaded portion and the end face is very high, and the contact condition can be checked by the coloring method. Contact rate.
