The electric motors of the electric spindle are all AC asynchronous induction motors. As they are used on high-speed machining machines, they need to quickly increase the speed from static to tens of thousands or even hundreds of thousands of revolutions per minute during startup. The startup torque is large, so the startup current should exceed the rated current of ordinary motors by 5-7 times. Muye Spindle Maintenance Company pointed out that its driving methods include frequency converter drive and vector control drive. The drive control characteristic of the frequency converter is constant torque drive, and the output power is proportional to the torque. The latest frequency converter of the machine tool adopts advanced transistor technology, which can achieve stepless speed change of the spindle. The drive control of the machine tool vector control driver is constant torque drive at the low speed end, and constant power drive at the medium and high speed ends

 

Mazak Spindle Maintenance Company, a technology integrated with electric spindles, will explain to you:

 

1. High speed bearing technology:

 

Electric spindles usually use composite ceramic bearings, which are wear-resistant and heat-resistant, and have a lifespan several times that of traditional bearings; Sometimes electromagnetic suspension bearings or static pressure bearings are also used, with no contact between the inner and outer rings and theoretically infinite lifespan;

 

2. High speed motor technology:

 

Electric spindle is a product of the fusion of electric motor and spindle, and the rotor of the electric motor is the rotating part of the spindle. In theory, the electric spindle can be regarded as a high-speed motor. The key technology is dynamic balancing at high speeds;

 

3. Lubrication:

 

The lubrication of the electric spindle generally adopts timed and quantitative oil air lubrication; Grease lubrication can also be used, but the corresponding speed needs to be discounted. The so-called timing refers to injecting oil at regular intervals. The so-called quantitative control refers to the precise control of the amount of lubricating oil each time through a device called a quantitative valve. Oil air lubrication refers to the blowing of lubricating oil into ceramic bearings carried by compressed air during on-site grinding of the spindle cone hole. Oil quantity control is very important, as it is too low to provide lubrication; Too much, when the bearing rotates at high speed, it will generate heat due to the resistance of the oil.

 

4. Cooling device:

 

In order to quickly dissipate heat from high-speed electric spindles, circulating coolant is usually applied to the outer wall of the spindle, and the function of the cooling device is to maintain the temperature of the coolant.

 

5. Built in pulse encoder:

 

In order to achieve automatic tool change and rigid thread tapping, the electric spindle is equipped with a pulse encoder to achieve accurate phase angle control and coordination with the feed.

 

6. Automatic tool change device:

 

In order to be applied to machining centers, the electric spindle (Demaji spindle maintenance) is equipped with an automatic tool changing device, including disc springs, broach oil cylinders, etc;

 

7. Installation method of high-speed cutting tools:

 

The widely familiar BT and ISO cutting tools have been proven unsuitable for high-speed machining in practice. In this case, high-speed tools such as HSK and SKI appear.

 

8. High frequency frequency conversion device:

 

To achieve a speed of tens of thousands or even hundreds of thousands of revolutions per minute for the electric spindle, a high-frequency frequency conversion device must be used to drive the built-in high-speed motor of the electric spindle, and the output frequency of the frequency converter must reach thousands or thousands of hertz.