The main structure of the electric spindle includes: built-in motor, support mechanism, lubrication mechanism, cooling mechanism, tool interface, loose broach mechanism, cover body, and housing. It is a mechanical and electrical integration that integrates high-efficiency, high-precision, high-speed, and high-reliability copper sleeve manufacturers into a power supply with a spindle motor as its power source, an inverter or drive controller as the drive source, and various tools and connection mechanisms as its output terminals. The product features low noise, low vibration, and compact structure. Its working principle is to convert the electric energy transmitted by the inverter or drive controller into the mechanical energy output by the shaft end, and to drive various tools or mechanisms to perform high-speed, high-efficiency cutting and rotary motion.
A, spindle lubrication and cooling
The lubrication of high-speed spindle bearings can be divided into the following four categories.
1.1 Grease lubrication
Motor spindles with a low value of dmn may be lubricated with grease. Due to the fact that the grease-type electric spindle is used for disposable grease, its service life is limited. Usually, the oilless bearing can be used for three months at full speed. Grease recommends the use of KLUBER's FIEX NBU-15 High Speed Grease. The filling amount is approximately 1/6 of the bearing clearance. When filling the grease, the cleanliness of the surrounding environment and the arrangement of the bearings in the group should be taken into account. Oil-and-lubricant-type electric spindles do not block the penetration of cooling water at the front end of the main shaft during high-speed rotation, so an airtight seal must be installed.
1.2 Oil and gas lubrication
The electric spindle using an oil-air lubrication system is called an oil-air lubrication electric spindle. The oil and gas lubrication electric spindle adopts multi-channel, atmospheric air, and less oil lubrication system, and its lubricating oil is controlled by a microcomputer to control the quantitative supply of the quantitative pump. Since the lubricating oil of the oil-and-lubricated electric spindle is supplied at a fixed time, the consumption of the electric spindle at a high speed can be greatly reduced. Turbine bearing crushing heat level is greatly reduced, the spindle's dmn worth further improvement. In general, the same type of bearing using oil and gas lubrication can be compared to the oil mist lubrication speed increased by 15% to 20%, is a variety of electric spindle in the highest speed spindle motor. Due to the large amount of gas and less oil used in oil-air lubrication electric spindles, it can effectively reduce or avoid environmental pollution. The main technical parameters for oil and gas lubrication are: gas source inlet pressure: 0.35MPa-0.4MPa, oil viscosity 20-50mm3/s, power supply voltage 220V (single-phase) power 60W, oil cup capacity 2-4L, Quantitative pump for each action is 0.2-1.0mL, quantitative components 0.025mL / times.
1.3 Oil mist lubrication
Motor spindles with higher speed factor dmn should be selected for oil mist lubrication. Oil mist lubrication means that the spindle oil is pressed out of the oil cup via compressed air, and the mist is injected into the bearing working area together with the compressed air in the oil pipeline so that the main shaft bearing is fully lubricated and cooled. The oil mist-lubricated electric spindle is continuously and continuously lubricated, so at full speed operation, two shifts can be used for 5-6 months. Oil is recommended to use 7 # spindle oil or 32 # turbine oil, mister optional secondary atomizer, the inlet pressure is controlled at about 0.3Mpa, the amount of oil is 80-90 drops / minute. The oil mist-lubricated electric spindle oil mist exhaust gas cannot be exhausted. Therefore, it should be used with caution because it is polluted by the environment. Non-closed equipment and non-environmental protection measures should be used with caution.
1.4 Injection Lubrication
The spindle of pressure lubrication oil that enters into the working area of the bearing through the sealed lubrication pipeline to make it fully lubricated is called the oil-lubricated electric spindle. Because this kind of electric spindle bearing can withstand the continuous lubrication of a long duration, its bearing lubrication effect is excellent, so it can obtain a high speed factor and high speed. However, this kind of electric spindle must rely on a complete closed oil supply system to maintain its work, so it should not be used in conventional production practice. In the defense industry testing machine when there is a sight.
Second, the spindle support method
2.1 Angular contact ball bearing support
The electric spindle with angular contact ball bearing as its support has high speed performance, high precision, simple structure, can withstand large radial loads, and can withstand considerable axial load. It is a large-scale support method for the spindle industry. . According to the different bearing configuration combinations, this type of motor spindle can be divided into two ways.
2.2 dual configuration
Spindle bearing duplex configuration can be divided into tandem (DT) combination and back-to-back (DB), face-to-face (DF) combination. In series (DT) combination, the two sets of bearings are the same, arranged in the same direction. Both can bear radial load, but also can bear a large axial load F in one direction. The electric spindles arranged in A-type can withstand large axial thrust F. The electric spindles arranged in B-type can withstand larger pulling force F'. At this time, the total load F(F') bearing is divided equally into the combination. On each bearing. That is, the load of each bearing is f = 1/2F(F'). Parallel (DB, DF) type combination, two sets of bearings symmetrically arranged. Among them, DB is arranged back to back, can bear radial load, can bear axial load in both directions at the same time, and can withstand higher overturning moment. DF is a face-to-face combination, can bear radial load, and can bear the axial load in two directions at the same time. Its ability to bear the overturning moment is poor, but there is a micro-adjustment function.
2.3 Multiple configuration
In order to achieve higher loading capacity and stiffness, angular contact bearings can be divided into multiple configurations such as triple, quadruple, and five-joint. Among them, triple and quadruple bearings are commonly used. The TT configured bearing can withstand large axial thrust, and the TT configured electric spindle is usually used for high-speed internal grinding of threaded copper tubes. TBT bearings can withstand large axial thrust, and can withstand a certain amount of axial tension, this configuration is suitable for high speed machining center spindle. QBC-equipped bearings can withstand large bi-directional thrust forces. This configuration is suitable for large-scale spindle machining centers. Angular contact ball bearings have high precision and high speed, and are generally used at the front end of the main shaft shaft.
Third, the cooling method of electric spindle
In order to satisfy high-precision machining and improve the reliability of the electric spindle motor, the electric spindle motor usually needs to consider the cooling structure. The cooling method is mainly divided into two types: forced cooling and natural cooling; forced cooling has liquid cooling and air cooling; liquid cooling has water cooling and oil cooling. Under the same conditions, water cooling is better than oil cooling, but water cooling Sealing and rust prevention requirements for cooling are higher than oil cooling. Air cooling is mainly two kinds of air blowing and air cooling. The former is more common in carpentry engraving spindles, and the latter is often used in electric spindles under special conditions. It is generally believed that the cooling of electric spindles is similar to the effect of water cooling. The natural cooling is heat exchange with the outside world through the electric spindle housing, and its power density is much smaller than that of the forced cooling electric spindle, so this kind of electric spindle has a small proportion.