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The role of pressure system of injection molding machine in forming is discussed

Release time:2018-06-01

The pressure control and measurement system is on the oil-pressure injection molding machine. All the movements are carried out by the oil road responsible for the following operations:

Screw rotation during plasticizing;

Slide way (injector nozzle close to injector bush);

Axial movement of the ejector screw during injection and pressure preservation; 

Close the base material to the ejector rod until the elbow is fully extended or the piston closing stroke is completed;

Start the jacking lever to jacking out the parts.   

In full voltage machine, all movement performed by equipped with a permanent magnet brushless synchronous motor through the machine tool industry has been used in the ball bearing screw, transform rotary motion to linear motion is the efficiency of the entire process depends in part on plasticizing process, among them, the screw plays a vital role.

Screw must ensure material melting and homogenization.This process can be adjusted by reverse pressure to avoid overheating.The mixing element must not produce high flow rate, otherwise, it will lead to polymer degradation.

Each polymer has a different maximum flow rate, and if it exceeds that limit, the molecule will stretch and the polymer host chain will break.However, the emphasis is still on controlling the forward axial movement of the screw during injection and pressure preservation.Subsequent cooling processes, including internal stress tolerance and warping, are important to ensure product quality.All this is determined by the quality of the mould, especially when optimizing the cooling passage to ensure effective closed-loop temperature regulation.The system is completely independent and will not interfere with mechanical regulation.

Mould movement such as closing die and ejecting die must be accurate and efficient.Mould movement such as closing die and ejecting die must be accurate and efficient.Contact maintenance is adjustable.Therefore, it can be concluded that the product quality is mainly determined by the system controlling the forward movement of the screw without considering the same additional conditions of energy consumption and mechanical reliability (such as mould quality).This adjustment is achieved by detecting oil pressure on an oil injection molding machine.

Specifically, the oil pressure activates a set of valves through the control panel, and the fluid ACTS through the controller and is regulated and released.   

Injection speed control includes open - loop control and half - loop control and closed - loop control options.The open loop system relies on a Shared proportional valve.Proportional tension is applied to the required proportion of fluid, which creates pressure in the injector cylinder and allows the injection screw to move forward at a certain speed.

Semi-closed loop system adopts closed loop proportional valve.The loop is closed at the position of the closing port, which controls the flow rate of oil by moving in the valve.The loop is closed at the position of the closing port, which controls the flow rate of oil by moving in the valve.Speed sensor (usually potentiometer type) is used in closed - loop system to detect the decrease of tension.The flow of oil from the proportional valve can be adjusted to compensate for the speed deviation.

Closed-loop control relies on specialized electronic components integrated with the machine.Closed loop pressure control during the injection and holding phase to ensure uniform pressure, and ensure the back pressure evenly in each cycle By detecting the pressure value of proportional valve adjustment, compensate the deviation according to the set pressure value.

In general, hydraulic pressure can be monitored, but detecting melt pressure in the nozzle or die cavity is another effective method.A more reliable solution is to manage the proportional valve by reading the nozzle or cavity pressure readings.Adding temperature detection on the basis of pressure detection is especially beneficial to process management.

It is also helpful to predict the actual weight and size of the molded parts according to the set pressure and temperature conditions.In fact, more materials can be introduced into the die cavity by changing the pressure-retaining pressure value to reduce component shrinkage in line with design tolerances (including preset injection shrinkage).Near melting conditions, the semi - crystalline polymer showed a significant change in specific capacity.For this reason, overcharge will not block the parts from ejecting.


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