In recent years, with the rapid development of the economy, the machine tool industry has also developed by leaps and bounds: it is reflected in the wide application of new technologies and the obvious improvement of enterprise benefits. At present, the mainstream consumer in the machine tool industry is CNC machine tools. Judging from the demand for CNC machine tools in domestic and foreign markets, the future CNC machine tool market will have the following characteristics: First, economical CNC machine tools will be the mainstream products in the future. 2. Adopting new technologies, reducing costs, and improving product stability are the keys to the survival of an enterprise. Let’s talk about the application of SAJ frequency converter in this industry by using frequency conversion speed regulation in machine tool driving:
1. The characteristics of spindle transmission of the original machine tool
Under normal circumstances, the driving system of the machine tool is driven by a motor to drive a gear box to drive and adjust the speed. It has the following characteristics:
1. Overview of the original system
A. Load-constant power nature
When the gearbox shifts, the change in torque is inversely proportional to the change in speed. Excluding the loss of the gearbox, it has the characteristics of constant power in the full power range.
- 1) The speed gear speed control box has 8 speeds: 75, 120, 200, 300, 800, 1200, 1500, 2000r/min.
- 2) The main rated parameters of the motor Rated capacity: 3.7kw Rated speed: 1440r/min Load characteristics: Constant power
- 3) The control method uses the 8 positions of the handle combination to control the opening and closing of the four clutches to obtain 8 combinations of gears, thereby obtaining 8 speeds.
B. Strong overload capacity at low speed. At low speed, the rated torque of the driving system after the gearbox is reduced will be much larger than the allowable working torque of the load, and it has a strong overload capacity.
2. Basic considerations when applying inverter speed regulation
- 1. The adjustment range of frequency conversion speed regulation is very wide. Generally, general-purpose frequency converters can realize stepless speed regulation in the range of 0-400HZ.
- 2. Considering that the machine tool requires harder mechanical characteristics. It conforms to the drive of frequency converter + ordinary motor (or frequency conversion motor) with hard mechanical characteristics. Generally, the ability to provide 150% load torque at low frequencies
- 3. Considering that the machine tool needs to have a strong overload capacity at low speeds. The inverter can provide 150% overload protection (60S), which can meet the requirements of the equipment.
- 4. After using frequency conversion speed regulation, it can simplify the original complicated mechanical drag mechanism such as gear box, high degree of automation, simple use and convenient maintenance.
- 5. The frequency converter has voltage (DC0-10V), current analog input interface, which can be well matched with the control signal of the numerical control system.
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