What are the process conditions for rubber extruder extrusion

Rubber extruder equipment is widely used in the manufacturing of semi-finished products such as rubber hoses, tire treads, inner and outer layer rubber of rubber hoses, and wires and cables. It can also be used for plasticizing raw rubber, filtering rubber materials, metal wire coating, and so on.

Characteristics of rubber extruder equipment:

1. Simple operation, easy process control, continuous and automated production, good production rate, and stable product quality.

2. Widely applicable. By changing the structure of the extruder screw and barrel, one of the functions such as plasticization, mixing, and shearing can be highlighted. Combined with different auxiliary machines, comprehensive processing of different processes can be completed.

3. According to different requirements of the product, various cross-sectional shapes of semi-finished products can be formed by changing the mouth shape of the machine head. It is also possible to use two (or three) machines to press out different components of rubber or multi-color composite tread rubber.

4. The equipment has a small footprint, light weight, simple machine structure, low cost, and high flexibility and maneuverability.

Both rubber tube extruders and rubber sealing strip extruders are collectively referred to as rubber extruders. Rubber pipes and strips are extruded using a rubber extruder. So, what are the principles and characteristics of rubber extruder extrusion molding?

1, The principle of rubber extrusion molding: The rubber material is heated and plasticized in the extruder, and is subjected to strong shear between the screw and the barrel. It is continuously transported forward by the rotation of the screw, and then extruded through the extrusion mold (also known as the die) under corresponding pressure to obtain the desired product shape.

2, Characteristics of rubber extrusion molding:

1. The rubber material is further mixed and plasticized by the rotation of the extruder screw, and the semi-finished rubber material that can be extruded is dense and uniform in quality;

2. Widely applicable, various cross-sectional shapes of rubber profiles and pre formed semi-finished products for pressing molds can be extruded by changing the die shape;

3. The speed of extruded products is not slow, and the production rate is good, which is conducive to automated production;

4. Extrusion molding is not limited by length and can produce long products that cannot be molded due to equipment limitations.

When extruding with a rubber extruder, the main things to pay attention to are temperature and speed. Correctly controlling the temperature can enable the rubber extruder to smoothly extrude, increase product output, and improve the quality of extruded semi-finished products, such as making the semi-finished products smooth in appearance, stable in size, accurate, and with low expansion rate. Low extrusion temperature of rubber extruder will result in rough surface, increased cross-section, and increased electrical load of semi-finished products; If the extrusion temperature is too high, it can cause the rubber material to burn and bubble. For this purpose, the extrusion process adopts an appropriate temperature distribution. Usually, different parts of the rubber extruder should use different temperatures. In general, the barrel is low and the nose is relatively good; The barrel can also be used as one or more temperature control sections, while the screw temperature is always higher than the barrel.

The feeding section of the rubber extruder generally has a lower temperature, which is beneficial for feeding and improving the uniformity of extrusion. For most rubber materials, a temperature setting of 43-60 ℃ is sufficient; For harder rubber materials, the temperature can be appropriately increased to 49-60 ℃.

The good temperature of the rubber extruder head and mouth has two benefits: firstly, it can reduce the expansion rate of the extruded product; Secondly, it can reduce the head pressure, which is beneficial for increasing extrusion output.

The lower temperature of the rubber extruder barrel can increase the viscosity of the rubber material. Therefore, in practical operation, controlling the barrel temperature to be lower than the screw temperature is beneficial for increasing production. However, the temperature difference between the rubber extruder barrel and screw is controlled within the correct range. A large temperature difference can increase production, but it can cause a decrease in the quality of extruded semi-finished products and easily lead to defects such as micropores and spirals; If the temperature difference is too small, it will reduce the yield.