Jinan Hengchuang CNC Machinery Co., Ltd. is specialized in the research, development and production of high-tech CNC products such as woodworking processing center, five-axis machining center, CNC woodworking engraver, mould processing center, CNC laser engraver and plasma cutting machine. <View more>

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Woodworking engraving machine drive servo distinction stepping drive


Woodworking engraving machine drive servo distinction stepping drive

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Customers often ask engraving machine-driven approach is good or servo drive stepper drives good, or some customers think sided servo drive very fast, do the following summary of these issues.

  Customers often ask engraving machine-driven approach is good or servo drive stepper drives good, or some customers think sided servo drive very fast, do the following summary of these issues.
  Stepper motor is a device for discrete motion, it and modern digital control technology are intrinsically linked. In the current domestic digital control system, the application of the stepping motor is widely used. With the advent of all-digital AC servo system, AC servo motors are increasingly used in digital control systems. In order to meet the development trend of digital control, motion control system use stepper motors or all-digital AC servo motor as the motor execution.  Although both the  control mode is similar (pulse train and direction signal), but in applications where performance and there is a big difference. Now on both performance  to make a comparison.  
  First, the control accuracy of different
  Two-phase hybrid stepping motor step angle is generally 3.6 °, 1.8 °, five-phase hybrid  stepping  motor step angle is generally 0.72 °, 0.36 °. There are also some high-performance stepper motor step angle is smaller. As Stone produced a wire walking machine for stepper motor step angle of 0.09 °; Germany Benguela hundred (BERGER LAHR) produced three-phase hybrid stepping motor step angle by DIP switch is set to 1.8 °, 0.9 °, 0.72 °, 0.36 °, 0.18 °, 0.09 °, 0.072 °, 0.036 °, compatible with the two-phase and five-phase hybrid stepping motor step angle.
  AC servo motor control accuracy is guaranteed by the rear end of the motor shaft of the rotary encoder. Panasonic full digital AC servo motor, for example, for the 2500 line encoder with standard motors, since the internal drive uses a four octave technology, its pulse equivalent to 360 ° / 10000 = 0.036 °. For motor with encoder 17, the driver receives 217 = 131 072 per motor revolution pulse, that is, its pulse equivalent of 360 ° / 131072 = 9.89 seconds. A step angle of 1.8 ° stepper motor pulse equivalent of 1/655.  
  Second, the different characteristics of low-frequency
  Easy stepper motor frequency vibration phenomenon occurs at low speeds. Vibration frequency and load conditions and drive performance, generally considered half of the vibration frequency of the motor load take-off frequency. This low frequency vibration phenomenon by a stepper motor works determined for the normal operation of the machine is very negative. When the stepping motor operates at low speed, the general techniques should be used to overcome the low frequency  vibration damping phenomena, such as the motor subdivision technology, plus damper, or drive.
  AC servo motor is running very smooth, vibration phenomenon does not occur, even at low speeds. AC servo system has a resonance  suppression  function, can cover insufficient mechanical rigidity and internal systems with frequency analysis function (FFT), can detect mechanical resonance point, easy system tuning.  
  Different three moments frequency characteristics
  Stepper motor output torque increases with the speed drops, and will be a sharp decline at high speed, so its maximum operating speed is generally at 300 ~ 600RPM. AC servo motor is constant torque output, which in its rated speed (3000RPM to 2000RPM or general) or less, can output rated torque above the rated speed for the constant power output.
Fourth, different overload
  Stepper motors generally do not have overload. AC servo motor with strong overload. Panasonic AC servo system, for example, it has a speed and torque overload overload. Three times its maximum torque is rated torque can be used to overcome the inertia of the load at the moment of starting moment of inertia. Stepper motor because there is no such overload, in the selection order to overcome this moment of inertia, often need to select a larger torque motor, and the machine during normal operation and does not require so much torque, giving rise to a moment waste phenomenon.  
  Five different operating performance
  Stepper motor control for open-loop control, starting frequency is too high or too large load step or prone to lose stall phenomenon, prone to stop excessive speed overshoot phenomenon, so as to ensure the control precision, should deal l, deceleration problem. AC servo drive system for the closed-loop control, drives the motor encoder feedback signal is sampled directly, the internal structure of the position and velocity loops, generally does not appear lost step stepper motor or overshoot phenomenon, controllability can be more reliable.
  Six different speed response performance
  Stepper motor to accelerate from standstill to operating speed (typically a few hundred revolutions per minute) need 200 to 400 milliseconds. Better acceleration performance AC servo system, Panasonic MSMA 400W AC servo motor, for example, accelerates from zero to its rated speed 3000RPM only a few milliseconds, it can be used to control applications that require fast start-stop.
  In summary, the AC servo system performance in many respects superior to the stepper motor. But in some less demanding situations are often used to perform motor stepper motor to do. Therefore, in the control system design process to control the various factors into account requirements, cost, choice of appropriate control motor.