On the control of the injection molding machine The modernized plastic injection molding machine is a typical system integrating machine, electricity, and fluid. This is due to the fact that there are many types of complex products, such as complex type products, less post processing, and processing. Material and plastic characteristics, since its inception, the development has been extremely rapid, currently more than 80% of the world's engineering production average plastic injection molding machine for processing.

The conventional injection machine uses a simple open-loop control, ie, it is preset. Controlled travel value In the manufacturing process of the equipment, preset locks are set as examples, value number mold force, cycle time, temperature, etc., which are generated by the process of the machine. For example, the temperature of the mold can be maintained by the temperature of the body heat plus control, and the temperature of the plasticizer can be maintained by controlling the power of the device through external heat. This kind of control method is conclusive, single simple structure anti-jamming ability is poor, the control temperature is also much lower, the former goal. The injection molding machine adopts closed-loop control, that is, the deviation of the measured line from the set value is controlled. The closed-loop control system uses a negative feed-back loop, which has strong anti-jamming capability. When the injection injection, velocity injection pressure, cavity temperature, cavity pressure, melt isostatic oil and temperature are misaligned in the production process, The machine adapts to the general condition and the control system should automatically correct the interference. The French side controls this anti-interference ability and has high control accuracy. The first step to French control is to use a computer for control, that is, build a real-time control system for counting and counting. It includes Direct Digital Control System (DDC), Control Computer Supervisory Supervisory System (SCC), Distributed Control System (DCS), and several types of control system types.

At present, there are three kinds of commonly used injection molding systems, namely the traditional relay type, programmable controller micro type and control type control type. In recent years, programmable logic controller (abbreviated as PLC) has been widely used in the injection molding machine control system due to its high performance and high performance. In order to improve the level and quality of the injection molding machine control system, a programmable computer controller (PCC) designed specifically for small and medium-sized control systems was developed at the secondary level of the PLC. PCC integrates the features of standard PLCs and industrial control computers, and has multiple operating systems for time division services. Data computing and processing capabilities are more powerful than PLCs. A PCC injection molding system is used to control the injection molding system including position control, temperature control, temperature control, fault control, and real-time display, which can greatly improve the quality of plastic products. High mention of benefits and benefits.

The control system plastic injection content is currently the plastic injection, process control system consists of two main parts: a system of control temperature is the system, to the temperature of the barrel, melt and mold two; control system is a movement control The system performs multi-stage switching on the injection molding process, speed, and pressure displacement.

In Wenqi, the precision of the control system has reached ±1°C. Precise precision in the control of the temperature of the precision injection molding is conducive to improving product quality to facilitate the original material and utilization rate, is a very important indicator. In the process of processing plastics, the temperature control mainly includes die and nozzle temperature control and control. The cylinder temperature is the temperature of the cylinder surface, and the wall thickness of the cylinder is relatively thick. Therefore, the key point of the thermocouple detection point is often unselected, and the temperature curve at different detection points is comparative. The heterodyne is large, so the double-point parallel detection, that is, when the surface of the barrel is set at the same depth and the thermocouple, will get a more stable temperature in the profit, the accuracy of line temperature control. The nozzle temperature directly affects the shear flow when the whole body melts and fluctuates. This has a great effect on the quality of the product, and the control accuracy of the sounding nozzle temperature is more demanding. The mold surface is the temperature of the cavity surface that is in contact with the temperature of the product. It will show the film filling and affecting the cooling and holding pressure process. The temperature of the mold can be controlled by the method of controlling the temperature of the heated carrier, and the temperature of the mold can be controlled directly. In the former method, the body-bearing temperature of the heated temperature port is the control object, which is relatively simple and can satisfy the demand for temperature control. When the temperature control accuracy is required to be higher, a two-step mining method is used for temperature control.

Injection pressure and pressure, velocity and sol back pressure are the first to control the volume of the injection part to change the number of three, its control accuracy directly affects the quality of the product for the first time.

The injection molding machine has a 5 to 10 injection molding stage with multiple shot and shot pressure and sol back pressure control. The precise control of the sol back pressure and the rate of consolidation and injection under injection pressure during the injection molding process is generally achieved through displacement/velocity sensing, transmission and pressure sensors, closed-loop injection controllers, and high-response servo-operated valves. . In addition, it is relatively simple to use a closed-loop proportional valve that is adopted by law, and to improve the control accuracy through the positioning core control of the valve ring closed of the proportional valve itself. However, one of the valve positions is a set variable, so the control accuracy is slightly worse.

The most important variable for the over-traveling of the control process is the clamping force. The clamping force is a necessary condition for a stable molding cycle that is now repeated. Another important variable in the migration process is the position. In the first place, the injection moulding machine of the surface-side one continuously pursues the improvement of efficiency, and the shift-sharpening speeds the mold to ring the molding cycle, and the quick-moving mold-removing itself has a higher requirement for reducing the control speed. On the other hand, due to the special opening and closing of arts and craftsmanship promotion, the precision of the control of the mold position is getting higher and higher.

PLC and PCC

Since the beginning of the 1960s, Taiwan, Taiwan, the United States and the United States have compiled a programmable controller PLC, PLC control technology has gone through 30 years, you can see, Cheng Lizhe made it with the development of modern computer technology and microelectronics. The software and hardware technologies have gone far beyond the embryonic stage of "initial control". Programmable computer controllers (PCC) are a new generation of programmable controllers that are trending.

Compared with the conventional PLC, PCC is a special control standard for control, operation, and process control and network control. It is an integrated intelligent control of the quasi-PLC, numerical control system and industrial computer. Device. The largest category of PCC is the design of application software that is similar to the time-division multi-task operation of large-scale computers. The conventional PLC tasks use a large-scale clock scanning or monitoring program to process the sequence logic instructions and the new brush and collector states of the external I/O channels. This process directly results in the size of the "controlled by LaiYi" application. This result is undoubtedly inconsistent with the real-time requirement of control in the I/O channel. PCC's system software solution to the United States to complete this problem, it uses a time-sharing multi-tasking machine with its construction software to run the platform, so that the application of the process is not related to the length of the sequence, but by the operating system The circulation. As a result, the weekly cycle of the determinant period distinguishes the application scanning cycle from the out-of-office real-life cycle, realizing real time. Need to control the system, of course, this control cycle can be calculated by the CPU computing power, according to the actual requirements of the user in advance, any changes.

The application tasks of PCC are mostly composed of a sequence module, which is beneficial to the development of project application software. Because this can be easily controlled according to different functional requirements of the division's various items, such as motion control, number alarm, data collection, PID adjustment calculation, communication control, etc. The number of these modules is sufficient to maintain a certain degree of interdependence between individual operations. These steps can be downloaded to the PCC's CPU after the individual modules have been independently programmed and debugged. Scheduling management under the parallel operation, to achieve the goal of control and control.

When PCC compiles different block modules, they have the flexibility to use different programming languages. This is especially useful for those who have not only been familiar with conventional PLCs, but also have a command table language in PCC. On the other hand, the use of a more advanced and intuitive high-level language (PL2000) can be used as a text language that controls all aspects of the language. The feeling of being controlled by the description of it is very simple and intuitive. In addition, the PCC should also be able to develop software with the ability to integrate "C" language programs, enhancing the ability to handle large data operations and processing.

The knots are hard on the side, and the PCC's features are significant. The core of the operating core is inside the computing module. The PCC is equipped with a large-capacity storage unit (100K to 16M) that is often used in the standby CPU for the CPU. This undoubtedly provides monitoring hardware for the strong application software of the system. basis.

The PCC's current hardware also specializes in designing a number of interfaces for industrial signals, such as high-frequency pulses, incremental encoding, temperature, weight signals, and ultrasonic signals. Interface module, etc. Each type of field signal will be easily connected to the PCC as the core of the system of digital system control word, the user can be based on the application of the system hardware I / O channel to a single or road more than ten, the number of ways Ten-way modules for the unit, dozens of points to hundreds of points of expansion and networking.

The functional advantages of PCC in ICBC's control and control industry reflect the development trend of integration of programmable controllers and controllers and computers and DCS (distributed industrial control systems), although this is still a technology. The lighter years are more technical, but it is increasingly being used in more and more application fields, showing development potential that cannot be underestimated. For attention, the general application of PLC control system is before the word, and the progressive development of the technology, the need for personalized, customized products, long-term increase in the demand for injection molding machine control is increasingly complex, fine More and more demanding, as the more advanced PCC control system will be rushed, according to a certain market share. On the other hand, it is clear that the PCC control system is not yet in production. Therefore, we have reason to believe that the PCC control system will not necessarily occupy a place in the press machine field. .