Fuzzy Control vertical injection molding machine barrel temperature

Date：2014/7/15 10:23:37

Vertical injection molding machine barrel temperature is an important parameter injection molding process, the temperature of the cylinder is to ensure effective control of the quality of the plastic molding important part. Currently, vertical injection molding machine heating method used mostly in tight external screw barrel solid paragraphs heating coil, the number of segments of different models heating coil may be different, according to the technical requirements of each of the temperature to adjust the temperature control is usually used temperature meter, but whether it is the use of two-position type PID temperature or temperature meter instruments are difficult to maintain good dynamic performance.
         A vertical injection molding machine barrel system requirements analysis
         Vertical injection molding machine barrel heating temperature achieved by the heating wire is energized, cooling and natural cooling is achieved by plastic take away some of the heat environment, we can see that the barrel is characterized by changes in temperature and rapid heating and cooling is slow, so when lower barrel temperature, away from the larger setting, should quickly heat up, when the cylinder temperature should be close to setting a slow warming, when the cylinder temperature reaches the set value, the heating of the barrel due to long maintained the temperature of the heat caused by natural cooling and plastic drop away, so that the cylinder temperature to maintain relatively stable within a set range.
         2 vertical injection molding machine barrel fuzzy control theory
         Rules vertical injection molding machine is the core barrel fuzzy control fuzzy control, input controller for temperature and the measured temperature setting deviation E and deviation change rate EC, plus the heat output of the heating wire set U. the set temperature t 0, t is the actual measured temperature, the deviation E = t0 -. t this time if the measured temperature is set to t 1, the last measured temperature is t 2, the temperature deviation changes in the rate of EC = t1 - t 2 E deviation of temperature into five fuzzy subset B (large), M (medium), S (small), Z (zero) and N (negative). [2 - 3] when t 0 - t> T 1, the corresponding B; if T 2 T2> 0 the rate of change of temperature deviation EC into three fuzzy sets P (n. ), Z (zero), and N (negative) when t 1 - t2> T 3, the corresponding P;. when - y 0.
         Vertical injection molding machine barrel plus heat electric wire U into four fuzzy subset B (large), M (medium), S (small) and Z (zero), and processing the voltage on the electric wire corresponding to the size the input-output characteristics of the system, the system output response to dynamic and static performance best, fuzzy fuzzy rules using the following conditional statement to describe. if E = B and (EC = P or EC = Z or EC = N) then U = Bif E = M and (EC = P or EC = Z) then U = Mif E = M and EC = N then U = S # 40 # 1 mechanical and Electronic 22006 (3) if E = S and (EC = P or EC = Z or EC = N) then U = Sif E = Z and (EC = P or EC = Z) then U = Zif E = Z and EC = N then U = Sif E = N and (EC = P or EC = Z or EC = N) then U = Z above description reflects the dynamic response of the control ÷ slow up fast down "ideas, and practical experience consistent for ease of SCM fuzzy subset from the precise control of the amount of judgment, E's on domain is expressed as {5, 3, 1, 0, -1}, EC's domain is expressed as {1, 0, - 1}, U's domain is expressed as {5, 3, 1, 0}.
         3 vertical injection molding machine barrel hardware circuit
         Temperature control system hardware by 89C51 microcontroller core circuit, shown in Figure 1, the temperature control is implemented by adjusting the voltage thyristor, if there is heated barrel section 3 or 4 sections heating coil, the SCR the control section 3 also has a corresponding group or 4.
         89C51 level P1 port generates a zero pulse after the sync pulse and synchronized drives and optocoupler input to the control electrode of the thyristor, the thyristor to control the on and off. LM311 voltage comparator and a monostable flip-flop MC14528 devices and other components zero trigger circuit.
         Zero-crossing sync pulse generating circuit triggered by the zero-crossing of the pulse as a trigger pulse to the triac temperature synchronization control circuit, and also a count pulse to the terminal T0 and T 1. P1 port generated by the fuzzy control algorithm corresponding to the control U is the amount of pulse signal, the level of conduction of SCR control, temperature regulation.
         4 vertical injection molding machine barrel Software Design
         The barrel temperature of each section were measured by a thermocouple, the A / D conversion, the set temperature and the measured temperature of the temperature deviation obtained by subtracting E, to the storage unit; the measured temperature of this reduction last measured temperature to obtain a temperature change rate of deviation EC, stored in the corresponding memory cell; then to determine the amount of the output voltage U of the fuzzy control rules based on the size of the deviation and the deviation change rate when the temperature is programmed to temperature. deviation, variance and rate of change of the control output corresponding to the temperature deviation is divided into three sections, the use of three different quantization factors to achieve fast and stable temperature control of the vertical injection molding machine. temperature deviation and the deviation change rate corresponding to the quantization factor to control the output, respectively, by the K e, K ec and K u K e to represent the greater the faster the system will rise, but the K e overshoot over the General Assembly to make the system becomes large;. K ec greater the slower system response, but K ec too small allowing the system to adjust for a long time, overshoot larger; K u greater the faster the system response, but also large overshoot, K u most sensitive response of the system, affecting more than K e, K ec large programs such as the design process. Figure 2.
         5 vertical injection molding machine barrel Conclusion
         Modern vertical injection molding machine barrel temperature control process on the increasingly high demand, therefore, vertical injection molding machine control method designed with low cost of hardware, software, simple design, high control precision and good dynamic performance characteristics, can to better meet the requirements.

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