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Keywords: Cable extruder,Wire extrusion machine,High-speed stranding machine,Single twisted cable machine,Wire and cable equipment,Wire and cable machinery,Three insulated wire equipment,Lathe parts
The role of the extruder non-inductive vector inverter
I. Introduction of Extruder Plastics are plasticized into a uniform melt through an extruder, and under the pressure established by plasticization, the screw is continuously cooled, quantitatively and pressure-extruded. Most thermoplastics use this method. Screw extruders come in many different models and sizes. The most common extruders are screw extruders. The main machine drive of the AC drive adopts the inverter, which can fully meet the process requirements of the extruder and achieve the necessary process control indicators. After the actual operation, the operation is stable, the product adaptability is strong, and the economic benefits are obvious. Features of the extruder drive Components of the extrusion molding unit An extrusion unit usually consists of a main machine (extruder), an auxiliary machine and its control system. Usually these components are collectively referred to as extrusion units. 1. Main unit The main unit of an extruder consists of three parts: extrusion, transmission and heating and cooling. The extrusion system is mainly composed of a screw and a barrel, and is a key part of the extruder; the driving system plays a role in driving the screw, and the screw needs to have the required torque and rotation speed during the working process; the heating and cooling system mainly ensures the material. And temperature control of the extrusion system during the forming process. 2. Auxiliary machine The composition of the auxiliary machine of the extrusion equipment depends on the type of product. Generally speaking, the auxiliary machine is composed of a component transparent device, a cooling device, a traction device, a cutting device, and a winding or stacking device of the product. 3. Control system The control system of the extruder is mainly composed of electrical appliances, instruments and actuators. Its main functions are as follows: (1) Control the driving motor of the main and auxiliary machines to meet the speed and power required by the process requirements, and to ensure The main and auxiliary machines can operate in coordination. (2) Control the temperature, pressure, flow rate and quality of the main and auxiliary machines. (3) Realize automatic control of the entire unit. Control of a conventional screw extruder 1) In a conventional screw extruder system, the screw is driven by a DC motor. In the case of direct drive, the screw is driven directly by the gearbox; in the case of indirect transmission, the screw is driven by the belt and the traction disk. The traditional DC motor itself has certain disadvantages: for example, the brush of the DC motor is replaced once a month. In a dusty or corrosive environment, the DC motor needs to be cleaned frequently, and sometimes even the DC motor is required from outside the workshop. Into the clean cooling air. 2) The disadvantage of the indirect drive screw extruder is that there is a belt slip, the belt will cause a certain energy loss, and more mechanical devices increase the possibility of wear and failure. The biggest drawback of DC motors is too much noise, brush fire, rotor pollution, motor temperature is too high, exhaust is insufficient and motor vibration. Therefore, the screw extruder using a DC motor has higher maintenance costs, and the initial cost of the DC motor is also higher. Second, the application of the inverter in the extruder The vectorless inverter is used in the extrusion equipment and has high-quality operation characteristics, which is determined by the good product performance that the vector-controlled inverter itself can provide. 1> Fast processor provides higher frequency response The built-in processor of the vectorless inverter provides high control accuracy, fast response frequency and good dynamic performance. The process requirements of the extruder are mainly to control the constant pressure of the outlet. When the equipment starts to work, the speed is controlled. When the demand pressure is reached, it is switched to pressure control. The switching process should have no impact and require high control accuracy of the inverter to respond to the pressure signal. 2> Vector control provides high torque output at low frequency. The main drive motor of the extruder mainly drives the screw to rotate after being decelerated by the parallel shaft helical gear reducer, and the constant torque is adjusted when the running speed is changed below the fundamental frequency. In the past, the V/f control inverter was used. Since the starting torque of the load should be considered, the corresponding torque boosting level should be set. If the torque boost setting is too high, the excitation will be too large at low frequency and light load, which may cause The motor is severely heated, which affects the stable operation of the equipment. The vector control type vectorless frequency converter not only ensures good output characteristics of the motor at low frequencies, but the automatic energy-saving operation function of the vectorless inverter reduces the output current with the change of torque, which not only saves energy but also eliminates The possibility of the above work hidden dangers. 3> Torque limit and slip compensation, the speed control accuracy is up to five thousandths.