What are the advantages of motor direct drive?
In daily life, we can see that some motors directly drive the pulley to work, and there is no need to use the reducer to connect the working machine with the motor. For example, some small rice milling machines directly drive the belt pulley with the gear reduction motor to drive the rice knife work in the rice milling machine. When the driving load, the motor need to go through the transmission device (e.g., transmission belt, etc.) to drive, and indeed can save transmission device, a motor directly driving load, the motor is adopted the "direct drive technology" direct drive motor.
What is "direct drive technology"?
Simply put, this is a technique for coupling a mobile load directly with an electric motor.
We know by ordinary motor drive mechanism is the electric motor of the motor shaft and then through a series of mechanical transmission mechanism such as coupling, screw, synchronous belt, rack, deceleration machine, and so on connected loads, in this process, from the mechanical point of view has increased the gap, the possibility of elastic deformation, friction damping and so on factors, resulting in equipment rigidity, response and to reduce the loss.
However, the use of direct drive technology to drive the load of the motor can avoid and reduce these losses.
I. advantages of direct drive motor
Direct drive motors have the following advantages:
1. Direct drive. Motor and drive between work piece and directly USES the rigid connection, without screw, gear, reducer, such as the intermediate links, the maximum extent, avoid the drive screw drive system of reverse clearance, inertia, friction, and the problem of insufficient rigidity.
High speed. The normal peak speed of linear motor can reach 5-10m/s. Traditional ball screw, the speed is generally limited to 1m/s, resulting in high wear.
3. High acceleration. Because there is no contact friction between the rotor and stator, the linear motor can reach high acceleration. The larger linear motor has the ability to achieve acceleration of 3-5g, and the smaller linear motor can achieve over 30-50g (wire welding machine). DDR is commonly used for high acceleration, DDL for high speed and high acceleration.
4. High precision. Because of the direct drive technology, the error caused by the intermediate mechanical drive system is greatly reduced. High precision raster detection is used for positioning to improve system precision, which can make repeated positioning accuracy within 1um and meet the application of ultra-precision occasions.
5. Wide range of motion speed. The running speed of linear motor can be at least 1um/s, and at most 10m/s, which can meet the needs of various occasions.
6. Low noise, simple structure, low maintenance cost, can operate in a clean environment, etc.
II. Classification of direct drive motors
Dc drive motor is mainly divided into linear motor (linear motor), torque motor (DD motor) and voice coil motor. Let's learn more about them.
In principle, the linear motor can be regarded as cutting the traditional servo motor along the radial direction and extending the circle of the motor into a straight line. When the coil (rotor) is connected with the current, the magnetic field is generated in the air gap between the stator, and the magnetic field and the stator permanent magnet are cut to generate the driving force, so as to realize the linear motion.
Classification of linear motor:
1. Coreless linear motor (u-type motor)
The rotor has only coil, no magnet and no suction between the stator. No groove effect, easy to achieve more stable movement, higher precision.
2. Iron core linear motor (plate motor)
The actuator only has a magnet inside the coil, and there is a strong suction between the stator, which can generate a large thrust.
3. Linear motor module
Voice coil motor
Voice coil motor is also a kind of direct drive motor, which is mainly used in z-axis light load, short stroke, high frequency round-trip motion, and force control
Typical application of direct drive motor
As a kind of new technology, has yet to be to expand the scope of application of direct driving motor, mainly used in the following equipment industry at present: FPC bolt-on machine, high-speed SMT machine, laser cutting, welding, high precision testing equipment, LED sorting binding, etc.
4. Selection of linear motor
The following introduces the selection of linear motor:
In triangle mode, acceleration is equal to 4 times displacement/time of motion squared
2. In trapezoid mode, the preset uniform speed can help determine the acceleration.
Acceleration = uniform speed/(motion time - displacement/uniform speed)
Relationship between the price of expansion sleeve and the service life