What are the types of EPS pre-expander?

Generally speaking, there are two types of EPS pre-expander, which were continuous type pre-expander and batch type pre-expander.

Continuous pre-expander machine: adopts mechanical control. The upper end of the expanding chamber has a discharge port, which can determine the density of foaming by the height of the movable gate. The raw material enters the expanding chamber from the lower part, and there is steam energy at the bottom of the chamber. In, the stirring shaft in the chamber drives the stirring rod to continuously stir, so that the expanding of the raw materials is more uniform, and the raw materials continue to enter from the bottom. After the steam is heated, the raw materials are gradually enlarged, and the material level continues to rise. Will flow out naturally. The higher the outlet opening, the longer the material stays in the chamber, the lighter it will be, and the lower the density; the lower the outlet opening, the shorter the time the material stays in the chamber will be the heavier it is sent, the greater the density. Continuous pre-expander machine is an early technology. Because the discharge port is always open, there will be a lot of waste of steam, and it cannot be made too light at once. The lightest density of expanding at a time is about 14 grams/liter. The control of the continuous pre-expander machine is very simple. Whether the steam pressure is stable or not has a great influence on the density of expanding. Therefore, our continuous pre-expander machine is equipped with a Japanese pressure reducing valve. In order to make the steam pressure in the machine more stable, We use the screw to feed the material at a uniform speed, and the uniform steam and the uniform feed are as uniform as possible. Of course, there is still a certain gap between the accuracy of the density and the intermittent pre-expansion machine. The operation of the continuous pre-expander machine requires certain experience, and several tests are required to foam a certain density. For example, if 15 grams/liter of material is to be sent, the operator opens the discharge port to a certain position and waits for the material to come out. Fill the measuring cup and weigh it. Adjust the height of the discharge port according to the high or low density. After several tests, it is basically accurate and follow this position. If the density needs to be changed, you need to re-adjust it according to this method. , So it is easier for the master to adjust. Of course, the new operator will become proficient after a period of time. Once adjusted, you don’t have to worry about it, and the work is automatic.

Batch type pre-expander machine: using PLC and touch screen control, closed chamber, each batch of raw materials is weighed frequently and then delivered to the chamber, and then heated and expanded. When the sensor detects the material level, it will give a signal to the PLC. PLC controls to open the discharge door to discharge all the materials. Since each batch of raw materials enters the same amount, the steam is stable, the pressure in the chamber is almost the same every time, and the material level of each expanding is to the same place, so the expanding density is relatively accurate. The batch pre-expander machine has a high degree of automation. After a density is expanded, the parameters of this density will be stored, and the parameters can be directly called for use when the density is sent later.

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Post time: Jul-05-2021