I. Description of electric screw presses

The electric screw presses uses a screw and a nut as a transmission mechanism, and a screw electric screw presses that converts the forward and reverse rotary motion of the flywheel into a vertical reciprocating motion of the slider by screw transmission. When working, the motor accelerates the flywheel to store energy, and at the same time pushes the slider down through the screw and nut. When the slider contacts the workpiece, the flywheel is forced to decelerate and then complete stop, the stored rotational kinetic energy is converted into impact energy, and the workpiece is hit by the slider to deform it. After the blowing, the motor reverses the flywheel, driving the slider up and back to the original position.

In recent years, due to the advancement of power electronics technology, the performance of electric screw presses has been greatly improved. Because this equipment structure is simpler than friction screw press, and there are no wearing parts such as friction belts, and the relationship between force and energy is easy to control, it has developed rapidly and has gradually replaced other forms of screw presses, such as die forging hammer and hot die forging press.

At present, the maximum tonnage of electric screw presses has reached 320MN, which is far greater than that of other die forging equipment. Generally, such large tonnage machine tools have larger processing parts and larger spindle power.

2, Control requirements

(1)     Excellent low frequency and large torque characteristics, high power inverter (315kw) can have a short acceleration time (about 1s);

(2)     Fast speed tracking control;

(3)     Fast torque response and small current fluctuation;

(4)     PLC brings high-speed counting function accurately;

(5)     Excellent performance of PLC analog module;

(6)     The excellent overall performance of HMI and PLC meets the control needs of machine tools;

(7)     Excellent overload capacity and environmental adaptability, high operational reliability;

(8)     Excellent EMC performance to avoid external interference caused by frequency conversion;

3, Design and description of system

(1)     Electric screw press equipment parameters: stamping tonnage of 1,000 tons, mold height of 300mm-500mm, KECEN provides PLC, HMI, VFD as a complete solution; 2 PCS of 132KW spindle motor;

(2)     The electrical control system includes: one KC500 inverter KC500-315G-4; two braking units DBU-320-4; one PLC; one PLC analog module; one HMI (7 inches);

(3)     The starting method is terminal start; the speed setting is controlled by a 0-20mA signal of the inverter given by PLC, and the HMI and PLC are communicated via RS232.

4, Solution advantages

(1)     The optimized open-loop vector control algorithm achieves excellent control performance, with large output torque at low-frequency, fast dynamic response performance, and strong stable speed performance;

(2)     Excellent current limiting characteristics, strong overload capacity, can effectively reduce frequency overload, overcurrent protection, and ensure maximum production continuity;

(3)     Superior AVR (Automatic Voltage Regulation) function, strong adaptability to the power grid, can be used in power grids such as long-term low power grid or grid fluctuations to ensure output voltage, current, speed stability.

(4)     Strong environmental adaptability, completely independent air duct design and flange installation mode can greatly improve the resistance to harsh environments such as oil pollution, dust, hot and humid environment;

(5)     Fast speed tracking, can track speed and output torque in time.