In CNC machine tools, the motorized spindle usually adopts the method of frequency conversion and speed regulation. There are three kinds of control modes: ordinary frequency conversion drive and control, vector control driver drive and control and direct torque control.
Ordinary frequency conversion is scalar drive and control, its drive control characteristic is constant torque drive, output power is proportional to speed. The dynamic performance of ordinary frequency conversion control is not ideal, the control performance is not good at low speed, the output power is not stable enough, and has no c-axis function. But the price is cheap, the structure is simple, and it is used in grinder and ordinary high-speed milling machine. The vector control technology imitates the control of DC motor, orients the rotor magnetic field and realizes the drive and control by vector transformation, which has good dynamic performance. The vector control driver has a large torque value when it is just started. In addition, the motorized spindle has a simple structure and small inertia, so the starting acceleration is large, which can realize the instantaneous allowable limit speed after starting. The latter can realize position and speed feedback, which not only has better dynamic performance, but also can realize c-axis function; while the former has poor dynamic performance and does not have c-axis function, but its price is relatively low.
Direct torque control (DTC) is a new type of High-Performance AC speed regulation technology developed after vector control technology. Its control idea is novel and the system structure is simple and clear. It is more suitable for the drive of high-speed motorized spindle. It can meet the requirements of dynamic and static characteristics of high-speed motorized spindle with high speed, wide speed range and high-speed instantaneous stop. It has become the field of AC drive A hot technology.
Scope of application:
Granite, marble, bluestone, sandstone and other stone carving
Granite and other hard stones can be carved to 5mm in layers
Marble and bluestone can be carved to 5mm at a time
- Stepper driver + stepper motor
Stepping system is the most used drive system in the market at present, the most popular is the three-phase hybrid stepping motor, which accounts for more than 90% of the market share. The reason is that the price is cheap, and the effect is good when equipped with the lassico subdivision driver. However, the defects are also obvious, such as resonance, noise, increased speed, reduced torque, easy to lose step when working for a long time, and excessive temperature rise of motor.
- Hybrid servo driver + motor
The use of hybrid servo has not been popular in China. There are many reasons for this. There are not many foreign manufacturers of hybrid servo. Compared with AC servo, the price has no great advantage, so it can only be used in some special industries. The improvements include: improving high speed performance, reducing heating and resonance.
- AC servo driver + AC servo motor
The use of AC servo in engraving machines is still relatively small, mainly because of the high price. In addition, the application of AC servo has certain requirements for the structure, electrical appliances, control system and transmission system of the machine tool. Just like the barrel principle, the shortest board determines the amount of water in the barrel. Therefore, the AC servo is generally applied to high-end models. AC servo has: fast response, high torque, high speed, high precision, less heating, long-time work, complete alarm system, etc. Disadvantages: different equipments need different servo parameters. High level technical engineers are required to adjust the parameters
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