Injection molding machine and on the control of it Modern plastic injection molding machine is a set of mechanical, electrical and fluid in one typical system, as this device has forming complex products, less post-processing, processing characteristics of the plastic variety, since its inception has grown rapidly, the current full Over 80% of the worlds products are used plastic injection molding machine for processing.Conventional injection molding machines generally use a simple open-loop control, that is, in accordance with a pre-set value of control. In the device manufacturing process, pre-configured parameter values, such as the clamping force, cycle time, temperature, etc., from the machine in the production process be maintained. For example, by controlling the die temperature can be maintained the temperature of heating fluid, plastic temperature can be outside the heating device by controlling the power to maintain. This control method of simple structure, however, poor anti-interference ability to control the temperature is relatively low.At present, more injection molding machine uses a closed-loop control, that is, according to on-line measurement value and set the value of the deviation control. Closed-loop control system uses a negative feedback loop, anti-jamming ability, when the injection speed, injection pressure, mold cavity temperature, cavity pressure, melt temperature and oil pressure due to interference in the production process, deviation of the machine through the adaptive control system for automatic correction of interference. This control method of anti-interference ability, high control accuracy. More advanced control method is to apply computer controlled, that is, to build a closed-loop real-time computer control system. It includes direct digital control system (DDC), supervisory computer control system (SCC), distributed control system (DCS) and multi-level control of several types.Commonly used injection molding machine control system has three kinds, namely, the traditional relay-based, programmable controllers and computer-based control type. In recent years, programmable logic controller (referred to as PLC) with its high reliability, high-performance characteristics in injection molding machine control system has been widely used. In order to improve the level of injection molding machine control system and quality, a higher level than the PLC, control system design specifically for small and medium programmable computer controller (PCC) came into being. PCC integrates a standard PLC and industrial control computer features, multi-task time-sharing operating systems, data computing and processing power more powerful than the PLC. PCC formed with injection molding machine control system in order to achieve, including position control, speed control, temperature control, fault control and real-time display the whole process such as injection molding a variety of control can greatly improve the quality of plastic products will help enhance economic benefits.Control of the contents of the injection molding machineInjection molding machine process control system mainly consists of two parts: First, the temperature control system in order to right barrel, melt and mold temperature control; second motion control system to the process of injection pressure, velocity and displacement multiple class switching.In the temperature control, its control accuracy has reached a 1 . Precise temperature control in precision injection molding that help improve product quality and availability of raw materials is a very important indicator. In the plastic processing, temperature control include barrel, nozzle and mold temperature control. Barrel temperature of the barrel surface heating temperature, due to relatively thick wall barrel, so the choice of thermocouple detection point is critical, and different test points on the temperature curve is a large difference. Therefore, parallel detection of double-point, namely, surface and deep in the barrel at the same time set the thermocouples, will be relatively stable temperature curve is conducive to temperature control accuracy. Nozzle melt temperature directly affects the passage of the shear flow, the quality of the products have a major impact, so the nozzle temperature control precision demanding. Mold temperature is in contact with the product mold cavity surface temperature, it will significantly affect the charge membrane, cooling and packing process. For the mold temperature control method can be used control the heat carrier temperature method can also directly control the mold temperature. In the former approach, in order to heat the temperature for the control of the export vector objects, is relatively simple and can meet the general temperature control requirements. When the temperature control precision is high generally use the second method of temperature control.Injection speed, packing press