The working principle of screw oil press

The working principle of screw oil press, broadly speaking, is due to the impelling action of the rotating screw axis in the pressing chamber to make the material moves forward continuously. In this process, due to the gradually reduced screw pitch of the pressing bolt, the thread width increases gradually and the root diameter increases gradually that the space of pressing chamber became smaller and produce strong extrusion on the material in the pressing chamber. As a result, oil outflows from the gap in the pressing cage and solid materials would be pressed into cakes and discharged from the end of the screw axis continuously.

In the process of pressing, the the compression force of material comes from the compressing pressure, the cake outlet resistance and friction resistance.

The compressing force

After being fed into the oil press, the material would be pressed into the pressing chamber first by the vertical downward pressure of the feeding spiral. Material in the pressing chamber moves forward by the rotating pressing bolt. In the process of advancing, the root cause that the material is compressed lies in the following two aspects:

The pressing bolt. The screw pitch of pressing bolt gradually narrows in the pushing direction and the thread width and the root diameter increase gradually.

The pressing chamber. The inner diameter of pressing chamber gets smaller in the pushing direction.

The compression process of material in the pressing chamber of several domestic screw oil press is usually achieved by two levels of pressing.

Primary pressing: material into the pressing chamber is compressed due to the gradually reduced space of pressing chamber and most of the oil can be extracted. Then, the structure of material has been more compact and would be sent into the secondary pressing by the pressing bolt.

Secondary pressing: when material just entering this stage of pressing, because of the sudden increase of the pressing chamber, the originally impact material would get loose, the structure is adjusted and oil circuit get cleared. Then, material continues to be pushed ahead by the pressing bolt and the space of pressing chamber gets much smaller than the first level so that material is pressed more drastically to extract oil as much as possible. At last, the material would be squeezed out of the annular cake outlet gap and become cakes that the secondary pressing completes.

Screw oil press is a kind of cooking oil refinery that is widely used at present. It has a series of advantages such as large continuous processing capacity, dynamic pressing, short time, high oil yield and low labor intensity.