Application of frequency converter in plastic extrusion machinery
Extruder is the basic equipment of plastic industry and chemical fiber industry. Many materials such as clay, food, metal, plastic, etc. can be extruded. The most common extruder is a screw extruder.
Introduction to Extrusion Machinery:
The solid particle raw material is first fed from the hopper, and then heated to plasticize or melt. The screw rotates to push the melted colloidal raw material to the exit of the extruder. The exit of the extruder is equipped with a specific die, which determines the shape of the final product. . Products such as plastic film, plastic pipe, profile and chemical fiber can all be produced by extruder.
The most common screw extruder is a single-screw extruder with a typical screw speed of 100 revolutions per minute; a twin-screw extruder is used for products that need to be mixed and extruded with two raw materials. The typical high-speed twin-screw extruder has a speed of 200 -500 revolutions per minute. The low-speed twin-screw extruder used for profile extrusion usually rotates at 10-40 revolutions per minute.
Equipment composition:
An extrusion equipment usually consists of the main machine (extruder), auxiliary machines and its control system. Usually these components are collectively referred to as the extrusion unit.
1) Host
The main engine of an extruder consists of a three-part system of extrusion, transmission, heating and cooling. The extrusion system is mainly composed of screw and barrel, which is the key part of the extruder; the driving system is the driving screw, which must ensure that the screw has the required torque and speed during the working process; the heating and cooling system is mainly to ensure the material And the temperature control of the extrusion system in the forming process.
2) Auxiliary machine
The composition of the auxiliary equipment of the extrusion equipment depends on the type of product. Generally speaking, the auxiliary machine is composed of a formulation device, a cooling device, a traction device, a cutting device, and a product winding or stacking device.
3) Control system
The control system of the extruder is mainly composed of electrical appliances, instruments and actuators, and its main functions are:
*Control the driving motors of the main and auxiliary machines to meet the speed and power required by the process requirements, and to ensure the coordinated operation of the main and auxiliary machines.
*Control the temperature, pressure, flow rate and product quality of the main and auxiliary machines.
*Realize automatic control of the entire unit.
Advantages of using inverter:
1) Improve efficiency
The efficiency of the variable frequency drive system is about 5% higher than that of the DC drive system of the same power. The efficiency of the AC motor is also higher than that of the DC motor. The frequency converter guarantees the excellent output performance of the motor without overheating. The energy consumption of the extruder in the general factory accounts for a considerable proportion of the total energy consumption. The input harmonic current of the inverter is much smaller than that of the DC drive and other general inverters. The total input power factor is guaranteed to be greater than 0.9, so there is no need to enlarge the factory The capacity of the power supply transformer and cables.
2) Improve the protection level
Extruders usually work in harsh, high-temperature or corrosive gas-containing environments. The protection level of AC motors is relatively high, while the protection level of DC motors is lower, and the maintenance cost for harsh environments will be greatly increased.
Advantages of frequency converter in extruder application:
*Fast processor provides higher frequency response: The built-in processor of AM300 inverter provides high control accuracy, fast response frequency and good dynamic performance. The process requirements of the extruder are mainly to control the pressure at the outlet to be constant. When the equipment just starts to work, the speed control is performed, and when the required pressure is reached, it must be switched to pressure control. The switching process should have no impact, and high control accuracy of the inverter is required to respond to the pressure signal.
*Automatic energy-saving control to optimize motor efficiency: The main drive motor of the extruder is mainly driven by a parallel shaft helical gear reducer to drive the screw to rotate. When the operating speed is changed below the base frequency, it is a constant torque speed regulation. The inverter has an automatic energy-saving control function, which can automatically adjust the voltage according to the load condition, so that the motor can run in the highest efficiency state
*Torque limit and slip compensation: The torque limit and slip compensation function make the output torque constant and the torque fluctuation is small, meeting the product process requirements.
Introduction to Extrusion Machinery:
The solid particle raw material is first fed from the hopper, and then heated to plasticize or melt. The screw rotates to push the melted colloidal raw material to the exit of the extruder. The exit of the extruder is equipped with a specific die, which determines the shape of the final product. . Products such as plastic film, plastic pipe, profile and chemical fiber can all be produced by extruder.
The most common screw extruder is a single-screw extruder with a typical screw speed of 100 revolutions per minute; a twin-screw extruder is used for products that need to be mixed and extruded with two raw materials. The typical high-speed twin-screw extruder has a speed of 200 -500 revolutions per minute. The low-speed twin-screw extruder used for profile extrusion usually rotates at 10-40 revolutions per minute.
Equipment composition:
An extrusion equipment usually consists of the main machine (extruder), auxiliary machines and its control system. Usually these components are collectively referred to as the extrusion unit.
1) Host
The main engine of an extruder consists of a three-part system of extrusion, transmission, heating and cooling. The extrusion system is mainly composed of screw and barrel, which is the key part of the extruder; the driving system is the driving screw, which must ensure that the screw has the required torque and speed during the working process; the heating and cooling system is mainly to ensure the material And the temperature control of the extrusion system in the forming process.
2) Auxiliary machine
The composition of the auxiliary equipment of the extrusion equipment depends on the type of product. Generally speaking, the auxiliary machine is composed of a formulation device, a cooling device, a traction device, a cutting device, and a product winding or stacking device.
3) Control system
The control system of the extruder is mainly composed of electrical appliances, instruments and actuators, and its main functions are:
*Control the driving motors of the main and auxiliary machines to meet the speed and power required by the process requirements, and to ensure the coordinated operation of the main and auxiliary machines.
*Control the temperature, pressure, flow rate and product quality of the main and auxiliary machines.
*Realize automatic control of the entire unit.
Advantages of using inverter:
1) Improve efficiency
The efficiency of the variable frequency drive system is about 5% higher than that of the DC drive system of the same power. The efficiency of the AC motor is also higher than that of the DC motor. The frequency converter guarantees the excellent output performance of the motor without overheating. The energy consumption of the extruder in the general factory accounts for a considerable proportion of the total energy consumption. The input harmonic current of the inverter is much smaller than that of the DC drive and other general inverters. The total input power factor is guaranteed to be greater than 0.9, so there is no need to enlarge the factory The capacity of the power supply transformer and cables.
2) Improve the protection level
Extruders usually work in harsh, high-temperature or corrosive gas-containing environments. The protection level of AC motors is relatively high, while the protection level of DC motors is lower, and the maintenance cost for harsh environments will be greatly increased.
Advantages of frequency converter in extruder application:
*Fast processor provides higher frequency response: The built-in processor of AM300 inverter provides high control accuracy, fast response frequency and good dynamic performance. The process requirements of the extruder are mainly to control the pressure at the outlet to be constant. When the equipment just starts to work, the speed control is performed, and when the required pressure is reached, it must be switched to pressure control. The switching process should have no impact, and high control accuracy of the inverter is required to respond to the pressure signal.
*Automatic energy-saving control to optimize motor efficiency: The main drive motor of the extruder is mainly driven by a parallel shaft helical gear reducer to drive the screw to rotate. When the operating speed is changed below the base frequency, it is a constant torque speed regulation. The inverter has an automatic energy-saving control function, which can automatically adjust the voltage according to the load condition, so that the motor can run in the highest efficiency state
*Torque limit and slip compensation: The torque limit and slip compensation function make the output torque constant and the torque fluctuation is small, meeting the product process requirements.
