精密注射机在控制方面的特点

The characteristics of precision injection molding machine in control

1) 对注塑成型参数的重复精度(再现性)要求高，宜采用多级注射反馈控制：

1) high precision (reproducibility) of injection molding parameters is required, and multi-stage injection feedback control should be adopted:

a.多级位置控制；

A. multilevel position control;

b.多级速度控制；

B. multilevel speed control;

c.多级保压控制；

C. multistage pressure maintaining control;

d.多级背压控制；

D. multistage back pressure control;

e.多级螺杆转速控制。

Speed control of E. multi stage screw.

位移传感器的精度要求达到0.1mm，这样可以严格控制计量行程、注射行程以及余料垫的厚度(射出监控点)，保证每次注射量准确，提高制品成型精度。料筒及喷嘴温度控制要精确，升温时超调量要小，温度的波动要小。精密注塑应采用PID控制，使温度精确度在±0.5℃之间为宜。

The precision of the displacement sensor is 0.1mm, which can control the metering stroke, injection stroke and the thickness of the remaining material (injection monitoring point) strictly, ensure the accuracy of each injection and improve the forming precision of the product. The temperature control of the barrel and nozzle should be accurate, the overshoot should be small when the temperature is raised, and the temperature fluctuation should be small. PID control should be adopted in precision injection molding, so that the accuracy of temperature should be between + 0.5.

2) 塑化质量要求，塑料塑化的均匀性不仅影响到注塑件的成型质量，还会影响到熔融塑料通过浇口时所受阻力的大小，为了得到均匀的塑化，设计专用的螺杆和使用专用的增塑技术必不可少。另外，机筒的温度也应精确控制，现在螺杆、机筒温度多采用PID控制(比例、微分、积分)，精度可控制在±l℃内，基本可满足精密注塑的要求，如果采用FUZZY控制方法，就更适合于精密注塑了。

2) plasticizing quality requirements, uniform plastic plastic not only affects the quality of injection parts, but also affect the melt through the gate by force, in order to get uniform plasticizing, for design and use of special screw plasticizing technology is essential. In addition, the barrel temperature should also be accurately controlled, now screw and barrel temperature control by PID (proportional integral differential), the precision can be controlled within l degrees, which can meet the requirements of precision injection molding, if the FUZZY control method is more suitable for precision injection molding.

3) 工作油的温度控制要高油温的变化导致注射压力的波动，必须对工作油采用加热、冷却的闭环装置，把油温稳定在50～55℃为宜。

3) the temperature control of working oil needs the change of high oil temperature, which leads to the fluctuation of injection pressure. The closed loop device of heating and cooling must be applied to the working oil, and the oil temperature should be stabilized at 50~55 degrees.

4) 保压压力的影响，保压对精度塑件的影响极大，准确地说，保压能较好地补缩，减小塑件变形，控制塑件精度，保压压力的稳定决定了塑件的成型精度，螺杆的终止位置不变是决定保压效果的决定因素。

4) effect of holding pressure, holding pressure has great influence on the precision of plastic parts, precisely, the pressure can effectively reduce feeding, plastic deformation, control precision plastic parts, pressure stability determines the forming precision of plastic parts, screw the end position is unchanged to determine the pressure the effect of the.

5) 对模具温度控制要求若冷却时间相同，模具型腔温度低的制品厚度要比温度高的制品厚度尺寸大。如POM、PA类材料，模温50℃时厚度为50～100μm的制品，在80℃时厚度减小到20～40μm，100℃时减小到只有10μm。室温也对精密制品尺寸公差有影响。

5) the mold temperature control requirements, if the cooling time is the same, the mold cavity temperature low product thickness than the high temperature product thickness size. For example, POM and PA, the thickness of the product is 50~100 m at 50, and the thickness decreases to 20~40 m at 80, and decreases to only 10 m at 100. Room temperature also has influence on dimensional tolerance of precision products.