Technical Guide Line

What are the advantages and principles of linear stepper motor?

Linear stepping motor has the advantages of high-speed response, high precision, high transmission stiffness, fast speed and unrestricted stroke length. It’s principle is to prevent the relative rotation of screw nuts and make the screw move axially. The following describes in detail "the advantages and principle of linear stepping motor"

I Advantages of linear stepping motor

1. High speed responsiveness Generally speaking, the dynamic response time of mechanical transmission parts is several orders of magnitude larger than that of electrical components.
Because some mechanical transmission parts with large response time constant, such as lead screw, are cancelled in the system, the dynamic response performance of the whole closed-loop control system is greatly improved and the response is extremely sensitive and fast.

2. High Accuracy
Due to the cancellation of mechanical transmission mechanisms such as lead screw, the tracking error caused by the lag of transmission system during interpolation is reduced. Through the linear position detection feedback control, the positioning accuracy of the machine tool can be greatly improved

3. High transmission stiffness and stable thrust
"Direct drive" improves its transmission stiffness. At the same time, the layout of the linear motor can be arranged according to the shape structure of the guide rail of the machine tool and the stress condition when the workbench moves. It is usually designed to be evenly distributed and symmetrical to make its motion thrust stable.

4. Fast speed and short acceleration / deceleration process
Linear motors were first mainly used in maglev trains (up to 500km / h). Now they are used in the feed drive of machine tools. Of course, there is no problem to meet the maximum feed speed of ultra-high speed cutting (up to 60 ~ 100M/min or higher). Because of its high-speed start-up, it can greatly shorten the "instant deceleration" of high-speed transmission, so as to greatly shorten the "instant deceleration" of high-speed transmission. The acceleration can generally reach 2~10g (g =9.8m/S2).

5. Unlimited stroke length
By connecting the fixed parts of the linear stepping motor in series on the guide rail, the stroke length of the moving parts can be extended infinitely.

6. Low noise during operation
Because the mechanical friction of transmission lead screw and other parts is eliminated, and the guide rail pair can adopt rolling guide rail or magnetic pad suspension guide rail (without mechanical contact), the motion noise is greatly reduced.

7. High efficiency
Because there is no intermediate transmission link, the energy loss during mechanical friction is eliminated

II. Principle of linear stepping motor

1. To mesh the screw with the nut, a method is generally adopted to prevent the relative rotation of the screw and nut and make the screw move axially. Generally, there are two methods to realize this conversion: one is the linear movement of the internal thread of the motor rotor, the internal thread of the rotor and the screw; the other is the linear movement of the external shaft of the motor, which is realized by the external drive nut and screw mesh.

2. Using the stepping motor electrical control equipment, without installing the external machine linkage device, the linear stepping motor is used to move in a precise straight line without current passing through the coil, which simplifies the design and enables it to rotate the output torque. This includes a power supply, a logic programmer, switching elements, and a variable frequency pulse source that determines the step rate.

3. The torque produced by the motor at a certain step speed. Dynamic torque can be expressed by pull in torque or pull-out torque. When the winding is in a stable DC current, the torque applied by the motor on the output shaft and the inertial measurement of the acceleration or deceleration of the object. Here refers to the inertia of the motor, that is, the rotating load or the motor rotor.

4. The motor is designed to raise the temperature. Motor temperature rise is the inherent characteristic of power loss and temperature rise when the motor is powered on. Electric energy loss mainly includes resistance heating (copper loss), iron loss and friction loss. Motor temperature is the sum of total loss heating temperature and ambient temperature. The pulse rate is equal to the stepping rate of the motor.

The above is the introduction of "advantages and principle of linear stepping motor".

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