Screw And Barrel Temperature Control
Screw and Barrel temperature control
Widely adopted at present, the screw cylinder resistance heating, heating device including cast aluminum heater, ceramic heaters, mica heaters, etc., using the heat source and the static mechanical shear joint action of plastic plasticizing. The cylinder temperature is controlled in a piecewise manner, and the temperature distribution is met with the requirements of the process, as well as the fast heating speed, temperature control precision and energy saving requirements. Generally, the shear heat of the processed plastic is less than the hour, and the temperature of the melt is considered to be the main heating temperature. In recent years, the new method of electromagnetic dynamic plasticization has been developed. In the stable working process, the external heating is not required, and it has the characteristics of high plasticization efficiency and low energy consumption.
Due to the screw cylinder temperature and its control effect directly affects the quality of injection molding products, for example, the products surface residual stress and shrinkage rate, and stability of product weight, which has become a measure of precision injection molding products quality is an important basis,Screw and Barrel thus cause the attention of the industry. The reliability of the cylinder temperature control device and its temperature control accuracy have become the key to the precision injection molding. Due to the large inertia of the heating system and the influence of environmental factors such as the power supply voltage fluctuation, it is often difficult to obtain the ideal quality factor, and the corresponding measures need to be taken. Based on relay switch control screw cylinder heating system, after the cylinder using the former three heating mode, its amount of overshoot,Screw and Barrel transition time and steady-state deviation and other measures of performance is not ideal.
Although the contactless silicon is the ideal device for controlling the high power parts, it is also used to control the heating of the cylinder and adjust the output power of the controlled silicon by changing the size of the guide Angle. The practical application confirms that there are three obvious defects in this method:
(1) instantaneous guide will produce great pollution to the power grid,Screw and Barrel which in turn will bring great disturbance to the control system itself, especially in the case of high power;
(2) the control circuit is more complex, especially for the trigger pulse circuit to be high, to meet the requirement of precise adjustment work;
(3) there is a nonlinear relationship between the output voltage and the control quantity guide Angle, and the adjustment of the control system can cause a lot of inconveniences, and the performance of the control system can deteriorate.
As a result, today's most used non-contact zero type solid state relay as high power control device, and based on the new control strategy to control the heating process, by adjusting the heating power to control the temperature.
During the installation process, check the relevant accuracy of the screw box to meet its performance requirement.
(1) adjustment of the parallel degree of the joint mode.
With precision level on two quenching rail longitudinal levelness coarse adjustment (lifting adjustable shim, the level of bubble stability in the middle), and the other with a parallel rule across two guide rails, rotate the level parallel ruler, make lateral levelness coarse adjustment. The large combined screw cylinder, a level is also used to inject a guide rail to adjust the degree of parallelism, and mount connects clamping device and injection device of positioning pin, tighten the connecting bolt and nut.
(2)Screw and Barrel check and adjust the level of the moving template guide column.
The horizontal adjustment of horizontal adjustment is carried out on the guide column with the precision level instrument. The horizontal plane is placed horizontally, and the measurement adjustment is carried out repeatedly until it meets the requirements. Horizontal measurement also requires a parallel ruler that spans two guiding columns.
Tolerances: Screw and Barrel the horizontal is less than or equal to 0.16mm/m, and the longitudinal is less than or equal to 0.24mm/m
(3) inspection and adjustment of the parallelism between the templates.
Template and fixed template datum of manufacturers in the factory has adjusted the parallel degree, is generally stable, but because the cause of the transportation and installation, may result in the parameter change,Screw and Barrel so to check and inspection after installation, the parameter calibration should be conducted by professionals.