Full-electric vertical injection induced electrical control system design

Date：2014/11/17 10:33:13

         Vertical injection molding machine is a special plastic molding machines, which uses a thermoplastic plastic, the rotation of the shear heat generated by the external heating and the screw into the plastic material in a molten state, and then the molten plastic is injected into the pre-designed cavity, after a certain time packing, cooling, you can get in line with the various uses of plastic products.
         Traditional vertical injection molding machine main drive is a hydraulic system consisting of pumps and valves with different directions to produce different pressure and flow to provide the driving force and the hydraulic cylinder and the moving speed of the motor requires. Fully hydraulic vertical injection molding machine from the traditional single-cylinder liquid-filled, multi-cylinder liquid-filled to today's two direct compression plate, there are certain advantages in molding precision, complex shape products, the technical difficulty but its control large, high precision machining, hydraulic technology is also difficult to master.
         All-electric injection molding machine is the development direction of vertical injection molding industry, which uses the electric motor plus ball screw drive mechanism as to achieve injection packing, plastics, unlock the top of the mold and control, low noise, high precision, easy to maintain workplace clean and products, and can greatly reduce the cost of cooling water, environmental protection, energy saving and performance has a unique advantage. Currently all electric motors used in vertical injection molding machines are produced by Japan's Fanuc permanent magnet motor, due to the high power permanent magnet motor manufacturing and control technologies are not mastered by our country, which imports more expensive. The author uses the drive in vertical injection molding machine, the motion controller (MC) and programmable logic controller (PLC) to control AC induction motor being successfully developed a cost-effective all-electric induction type vertical injection molding machine.
A vertical injection mechanic conditions
         Vertical injection molding machine working process is as follows:
         (1) Clamping: divided into fast clamping, low voltage clamping, high voltage clamping three phases.
         (2) injection seat forward: the nozzle close to the mold.
         (3) injection: the screw to a certain pressure and speed of the front end of the barrel in the molten state plastic into the mold cavity.
         (4) packing: Supplementary products due to cooling and contraction section is used.
         (5) plastics: satisfy certain prepared density distribution and the volume of the molten plastic.
         (6) Back: to prevent the plastics melt overflow due to expansion from the nozzle, appear / salivation 0 phenomenon.
         (7) Cooling: cooling cavity molding plastics.
         (8) mold: mold into slow and fast mold, mold deceleration in three stages.
         (9) top out: the product from the mold ejection.
         Among them, the rotational speed of the motor plastics, unlock mode speed, injection speed needs to focus on speed control; holding pressure and the need to focus on plastics backpressure pressure control; injection, unlock mold, ejector, plastics require precise position control; feed cylinder temperature, the cooling temperature needs to be focused on the temperature control.
2 electronic control system works
         Vertical injection molding conditions seen by mechanic, vertical injection molding machine to run each part is a certain sequence and time interval link up. To achieve precise control of the sequence of these processes, in the present system, the selection of a pair of electrical connection with the PLC to control the motor, inverter, and other various components of the sensor between the coordinate.
         The control system can be divided into three main parts: the host controller, MC and drives. Among them, the control panel, PLC and programmable operation display (POD) collectively referred to as the host controller, the main function is to set control parameters, display control results, coordinating all aspects of the operation of the machine sequence. MC under the coordination of the host controller, motion control, and the results and the associated state of the control is transmitted to the host controller. As a drive inverter main function is to receive a command signal MC, the drive motor, to complete the appropriate action.
3 Electronic Control System Components Introduction
3.1 work
         Using PLC induction type full electric vertical injection molding machine has the following three kinds of different ways of working:
         (1) vertical injection molding machine manually by pressing the manual button on the control panel, you can check whether each segment is running normally, the communication module can be connected to a personal computer (PC) PLC via RS232 line on running, real-time observation of program execution situation.
         (2) semi-automatic semi-automatic button is pressed, and the front and rear vertical injection molding machine when the safety door is closed, vertical injection molding machine will stop after the completion of a cycle of work waiting for the next start.
         (3) The only difference between automatic and semi-automatic mode of operation is that it is not just the completion of a cycle but continuously run down. When the vertical injection molding machine to work properly, the whole production process is automatically controlled manner.
3.2 PLC
         Since the system input, multiple output signals, the operation control panel including a command signal is given, the security gate enable signal is off, the cylinder temperature, MC operation signal, MC feedback signals, the operation is completed, the operation more complicated control for coordinating the operation POD order and implement data access, use a Fuji SPBNW0P60R-31 programmable controller, expansion modules for NW0E32R-3, and in order to thermocouple temperature data sampling, the addition of a temperature control module. Between the main module and extension modules are connected by a bus to transfer data.
         PLC program development using Fuji Electric provides software development, communication protocol is EthernetUDP / IP. PLC program comprising: obtaining and processing I / O signals; determine fault and abnormal conditions; control the timing of judgment; output operation instruction; thermocouple data sampling.
3.3 MC
         MC choices are TECHE-HOLON axis dedicated controller chip HITACHISH27045F. Its components include a substrate TH-A0020A, ENCODE processing board TA0021, digital card TH-A0003A (4 块), A / DD / A converter board. MC built-in Ethernet communications card has a communication function.
         ENCODE board which is mainly used to deal with encoder signals, in this system, the injection motor, motor lock mode, the top of the motor using an incremental encoder count. Every one rotation of the motor, the encoder outputs 2500 pulses chip PCL6045 by the encoder signal processing to give an injection, mold opening and ejection of the position information.
         I digital card system for reading / O capacity. Digital input operation command signal sent to the main PLC, pursuant to this signal MC performs the following actions to go. Digital output corresponding to injection mold opening, the top of the inverter, the output of the first four action figures plate is given MC completion signal as an input command PLC signal. Digital board connected via ARCNET MC.
         MC used in industrial control field currently the most widely used L_iTRON real-time operating system, which is stored in C language program is the core of the whole control system. Development of control programs is the use of development tools and development environment HitachiEmbeddedWorkshop, programming, debugging, compiler links in which the completion of the compiled program downloaded to the MC via Ethernet communication chips.
3.4 Drive Select
         The system selects the four inverters respectively injection motor, motor lock mold, plastic motor and the top of the motor is controlled, which controls the injection, unlock mode, the top of the motor 3 Fuji FRENIC5000VG7 vector frequency inverter, and plasticizing motor movements are simple and without vector control function, the choice is Fuji FRENIC5000G11 drive. These drives have parameter self-tuning function, when used with general-purpose motor, the first self-tuning, you can achieve better control requirements.
4, run and main technical performance indicators
         The induction of type full electric vertical injection molding machine has been successfully developed over the past year, is further perfected. Its operating procedures:
         (1) according to production requirements, to set the speed of mold opening in the POD, the cylinder pressure and temperature values and other parameters partition.
         (2) Select "Manual" on the control panel, "semi-automatic", "Automatic" operating mode in which three kinds of one or other features (such as the origin of self-clamping looking, manual thimble, etc.).
         (3) PLC according to the received command signal and the actual feedback value, the MC determines the next action.
         (4) MC according to PLC command signal and speed, pressure and other motion parameters, after a certain amount of control algorithm processing, gives control signals to the inverter.
         (5) rotation of the drive motor inverter, the motor connected with the ball screw via a timing belt, the circular motion into linear motion, in order to achieve control of speed, pressure or position.
         Nearly a year of testing showed that the induction of type full electric vertical injection molding machine control performance, productivity, reliability, energy savings and clean environment all have excellent performance. It compares with a considerable size hydraulic vertical injection molding machine, no matter what the production of plastic products, energy-saving rate above 30%; it does not use hydraulic oil, so the oil pollution problem does not exist, easy to maintain workplaces and products clean, and significantly reduce the cost of cooling water; low running noise; easy to operate and has a variety of protection features; inverter speed control accuracy and stability, reduce the lock-mode vibration, avoid equipment impact, which makes the life expectancy; short response time, greatly improving production efficiency, significantly reduce product costs.
5 Conclusion
         The author developed an all-electric induction type vertical injection molding machine performance as much domestic manufacturers to develop AC permanent magnet synchronous electric vertical injection molding machine, but the cost was reduced by about 50%.
         At present, due to the special-induced motor vector control inverter and ball screws expensive, coupled with restrictions on the production scale, so that the manufacturing cost of the all-electric vertical injection molding machine for domestic sizable vertical injection molding machine hydraulic 3-4 times, but its performance is much better than the latter, and as technology advances, the related electrical component costs will be reduced, then finished industrial production will make more cost-effective to induce type full electric vertical injection molding machine, the user's investment You can get a more effective return.

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