一.The characteristics of the technology parameters.

The injection pressure:

The ordinary injection molding machine: 147 ~ 177MPa of precision injection molding machine: 216 ~ 243 MPa ultra high pressure injection molding machine: 243MPa above, usually in the Between 243 ~ 392 MPa.Precision injection molding machine can realize high pressure forming is good: A. improve the accuracy and quality of precision products, injection pressure has the most obvious effect when the pressure reaches 392 MPa on molding shrinkage rate, molding shrinkage rate is almost zero. And then the precision of products is only affected by mould control or the environment. Experiments show that: the pressure injection from 98 to 392 MPa, the mechanical strength can be increased by 3 ~ 33% parts. B. can decrease the precision products wall thickness and improve the forming length in the case of PC, the injection pressure of 177 MPa can molding 0.8mm wall thickness, and precise injection pressure molding thickness above 0.45mm at 392 MPa. Ultra high pressure injection machine can obtain flow length greater than products. C. to increase the injection pressure can be fully Tourne injection rate effect. In order to achieve the rated injection rate, there are two ways: one is to improve the maximum injection system pressure; two is the transformation of the injection device or injection system parameters, including the screw parameters; injection speed, precision injection machine high requirements

Injection speed precision hydraulic injection molding machine to reach more than 200mm/s, the injection speed of fully electric injection molding machine can reach more than 300mm/.

二. The characteristics of precision injection machine in terms of control

①Repeat accuracy of injection molding parameters (reproducibility) of high requirements, should use the multi-stage injection feedback control

1 multi position control;

2 multi speed control;

3 multistage holding control;

4 multi-stage back pressure control;

5 stage screw speed control.

Displacement sensor accuracy at least will reach 0.1mm, which can strictly control the metering stroke, injection stroke and surplus material pad thickness (injection control point). Ensure that each injection volume accurately, improve product accuracy.

②The cylinder and nozzle temperature control precision,

Heating temperature control system overshoot is small, temperature fluctuations small. Precision injection molding by PID proportional, integral, differential temperature control, temperature accuracy ± 1 ℃, ultra precision injection molding machine temperature control precision is ± 0.1 ℃, the temperature deviation can be controlled in ± 0.2 ℃.

③The hydraulic oil temperature control of injection molding machine

Changes in temperature resulted in injection molding machine injection pressure fluctuation, must by the hydraulic oil cooling device, the oil temperature is stable at 50 ~ 55 ℃ appropriate.

④The control requirements of the mold temperature

Late stage hydrothermal temperature of mold parts shrinkage have considerable influence, will also affect the workpiece surface quality and the degree of crystallinity, will also affect the mechanical properties of the. If the cooling time, mold cavity temperature low thickness, thickness of product than to high temperature high.