xiehe model

Electric spindle is a new technology that has emerged in the field of CNC machine tools in recent years that integrates machine tool spindles and spindle motors. Together with linear motor technology and high-speed tool technology, it will push high-speed machining into a new era. CNC machining electric spindle is a set of components, which includes the electric spindle itself and its accessories: electric spindle, high-frequency conversion device, oil mist lubricator, cooling device, built-in encoder, and tool change device. Next, the editor of Xiehe Machining Factory will briefly introduce to you the structure of the motor spindle of the CNC machining center.

High-speed spindle is an important key technology in high-speed cutting technology and an important component of high-speed cutting machine tools. It requires high dynamic balance, good rigidity, high rotation accuracy, good thermal stability, the ability to transmit sufficient torque and power, the ability to withstand high centrifugal force, and an accurate temperature measurement device and efficient cooling device. High-speed cutting generally requires the spindle speed capability to be no less than 40,000r/min and the spindle power to be greater than 15kW. Usually, an electric spindle component with an integrated spindle motor is used to achieve direct transmission without intermediate links. Most of the motors use an induction integrated spindle motor. Currently, hot pressed silicon nitride (Si3N4) ceramic bearings, liquid dynamic and static pressure bearings and air bearings are commonly used. Lubrication mostly uses oil-gas lubrication, jet lubrication and other technologies. Spindle cooling generally adopts internal water cooling or air cooling of the spindle.

1. Working principle diagram of ceramic bearing high-speed spindle

The picture above shows the working principle diagram of a ceramic bearing high-speed spindle. It uses C or B-level precision angular contact ball bearings. The bearing arrangement is similar to the traditional grinder spindle structure; it adopts a "small bead dense ball" structure and the ball material is Si3N4; it adopts an electric spindle (motor Integrated with the main shaft); the characteristic value of the bearing speed (= shaft diameter (mm) × rotation speed (r/min)) is 1.2 to 2 times higher than that of ordinary steel bearings, up to 0.5 to 1×106. The rotation accuracy is high, the rotation error of the hydrostatic bearing is below 0.2 μm, and the rotation error of the aerostatic bearing is below 0.05 μm; the power loss is small; the characteristic value of the speed of the hydrostatic bearing can reach 1×106, and the characteristic value of the speed of the aerostatic bearing Up to 3×106. Aerostatic bearings have a smaller load-carrying capacity.

Compared with steel balls, the advantages of ceramic bearings are:

(1) The density of ceramic balls is reduced by 60%, which can greatly reduce the centrifugal force;

(2) The elastic modulus of ceramics is 50% higher than that of steel, giving the bearings higher stiffness;

(3) Ceramic friction coefficient is low, which can reduce bearing heating, wear and power loss;

(4) Ceramics have good wear resistance and long bearing life.

2. Magnetic bearing high-speed spindle

The picture above shows the working principle of a high-speed spindle with magnetic bearings. The spindle is supported by two radial and two axial magnetic bearings. The gap between the stator and rotor of the magnetic bearing is about 0.1mm. ?High stiffness, about 10 times the stiffness of the ball bearing spindle. The characteristic value of rotation speed can reach 4×106. Rotation accuracy mainly depends on the accuracy and sensitivity of the sensor, as well as the performance of the control circuit, and can currently reach 0.2μm. The mechanical structure and circuit system are relatively complex; and because of the large amount of heat generated, the performance requirements for the cooling system are relatively high.

The above content is the motor spindle structure of CNC machining center. I hope it can be helpful to everyone. If you want to know more about CNC machining center, please call Xiehe Processing Factory, we will serve you wholeheartedly.