The electric spindle is a new technology that combines the machine tool spindle and the spindle motor in the field of CNC machine tools. The main shaft is a set of components, which includes the electric main shaft itself and its accessories: electric main shaft, high-frequency variable frequency mounted electric main shaft, which is a new technology in the field of CNC machine tools that integrates the main shaft of the machine tool and the main shaft motor. The main shaft machining is a set of components, which includes the electric main shaft itself and its accessories: electric main shaft, high-frequency frequency conversion device, oil mist lubricator, cooling device, built-in encoder, tool change device, etc. This type of transmission structure of the spindle motor and the machine tool spindle “combined into one” makes the spindle components relatively independent from the transmission system and the overall structure of the machine tool, so it can be made into a “spindle unit”, commonly known as “electric spindle”. Features high-speed, high-precision, low-noise, inner ring with lock structure.
Together with linear motor technology and high-speed tool technology, it pushes high-speed machining to a new era. The electric spindle includes the electric spindle itself and its accessories, including the electric spindle, high-frequency frequency conversion device, oil mist lubricator, cooling device, built-in encoder, tool change device, etc. The rotor of the electric motor directly serves as the main shaft of the machine tool, and the housing of the main shaft unit is the motor base, and cooperates with other parts to realize the integration of the electric motor and the main shaft of the machine tool.
The electric spindle is directly driven by the built-in motor. Because there are no other transmission links in the middle, it has the advantages of compact structure, light weight, small inertia, small vibration, low noise, fast response, high precision, etc., and high speed and high power. Simplified mechanical design and easy spindle positioning is an ideal structure in high-speed spindle units. However, the cost of the electric spindle is relatively high, and the daily maintenance requirements are relatively high. Due to the hidden drive mechanism, abnormal wear and mechanical damage are not easy to detect. Compared with the mechanical main shaft (belt shaft, direct-connected main shaft), the electric main shaft is mainly driven by a belt or a coupling. The transmission efficiency is relatively low and the accuracy is not high. However, the structure is relatively simple, the cost is low, and it is easy to repair and maintain. .
Here are some precautions for the use of the characteristics of the electric spindle:
- 1. The electric spindle and the inverter should be used together. The specifications and parameter settings of the inverter should match the rated parameters of the electric spindle. If the setting is incorrect, the electro-spindle will be burnt out.
- 2. The water-cooled electric spindle must ensure the normal operation of the cooling cycle system before use. It is strictly forbidden to use it without cooling. The connection between the cooling water pipe and the water nozzle must be reliable and no leakage.
- 3. The coolant must be clean and free of oil, and the temperature should be controlled at 5-30 degrees Celsius. If the ambient temperature is higher than 40 degrees Celsius, the cooling medium must be forced to cool.
- 4. During the storage and transportation of the electric spindle, the state of high-speed grease inside the bearing will change, and the customer should run in at a low speed before using it. The running-in starts from the lowest speed of the electric spindle. If the running is started at high speed without running-in, abnormal noise, noise, heat and other phenomena will occur, which will affect the service life of the electric spindle bearing.
- 5. The electric spindle must be preheated every time it is used, and then processed after the electric spindle reaches the processing speed, and it is forbidden to knock the electric spindle. During transportation and storage, it is also necessary to prevent knocking. Special attention is paid to the machining shaft end.
In response to these precautions, take the Siemens system as an example and the alarm failure at the customer site as an example to illustrate:
1. Customer 1’s electric spindle failure alarm:
Alarm number: 25201 alarm
Reason analysis: This alarm is caused by the interference of the electric spindle signal,
Specific treatment method: add a magnetic ring anti-interference shielding ring externally. Due to the long signal line of the main shaft, a magnetic ring of 3 meters was added at that time, and the alarm was subsequently canceled.
2. Customer 2 electric spindle failure alarm:
Alarm number: 207910
as the picture shows:
Cause analysis: This alarm is caused by the spindle temperature being too high
Specific treatment methods: increase the cooling water of the water cooler, the cooling water of the water cooler is not enough, and the insufficient cooling leads to the excessive temperature of the spindle motor.
3. The size deviation of the electric spindle machining is too large:
Reason analysis: This workpiece size deviation is mainly caused by the thermal expansion of the spindle. Although our company added a water cooler to cool the spindle temperature, and the customer is also a constant temperature workshop, the thermal expansion coefficient of the electric spindle at different speeds is different. Direct cnc machining will As a result, the size deviation is too large, the error is up to 5 wires, and they are all negative tolerances, indicating that the customer performs the processing without fully heat the machine.
Specific treatment method: increase the time of warming up, every time when the machine tool is processed, ensure that the warming up machine is half an hour, and increase from low speed to high speed successively, so that the processing size can be guaranteed.
4. Electric spindle tool change card
Alarm number: 700014 Alarm number: 700017
Reason analysis: The signal of loosen clamping tool is abnormal when the spindle is changing the tool, which causes the mechanical arm to change the tool and jam.
Specific treatment method: Check the signal switch of the loose clamp knife, and find that the empty knife detection switch is abnormal during tool change. After cleaning the spindle taper hole, the signal is normal and the tool change is normal.
The above are the electro-spindle failures encountered in daily service and the countermeasures