What are the auxiliary equipment for rubber extruders

The transmission part of a rubber extruder is usually composed of an electric motor, a gearbox, and bearings. During the extrusion process, the screw speed needs to be stable and cannot change with changes in screw load, in order to maintain uniform quality of the resulting product. However, in different situations, it is necessary to require the screw to be variable speed in order to achieve the requirement that one device can extrude different rubbers or products. Therefore, this section generally uses devices such as AC rectifier motors and DC motors to achieve continuously variable speed, with a general screw speed of 10-100 revolutions per minute. The function of the transmission system is to drive the screw and supply the torque and speed required by the screw during the extrusion process. It usually consists of an electric motor, a reducer, and bearings. Under the premise of basically the same structure, the manufacturing cost of the reducer is roughly proportional to its external dimensions and weight. Due to the large shape and weight of the gearbox, it means that more materials are consumed during manufacturing, and the bearings used are also larger, which increases the manufacturing cost.

What is extruder auxiliary equipment? The auxiliary equipment of the rubber extrusion unit mainly includes a pay off device, a straightening device, a preheating device, a cooling device, a traction device, a meter counter, a spark testing machine, and a winding device. The purpose of the extruder unit is different, and the auxiliary equipment used for selection is also different, such as cutters, dryers, printing devices, etc.

Straightening device: rubber extrusion waste type. One common cause is eccentricity, and various types of bending of wire cores are one of the important reasons for insulation eccentricity. In the extrusion of the sheath, scratches on the surface of the sheath are often caused by the bending of the cable core. Therefore, straightening devices are essential in various extrusion units. The main types of straightening devices are: drum type (divided into horizontal and vertical types); Pulley type (divided into single pulley and pulley group); Twisted wheel, serving multiple functions such as dragging, straightening, and stabilizing tension; Roller type (divided into horizontal and vertical types), etc.

Cooling device: The molded rubber extrusion layer should be cooled and shaped immediately after leaving the machine head, otherwise it will deform under the action of gravity. The cooling method usually adopts water cooling, and is divided into rapid cooling and slow cooling according to different water temperatures. Rapid cooling refers to the direct cooling of cold water. Rapid cooling is beneficial for the shaping of rubber extrusion layers, but for crystalline polymers, due to sudden heat cooling, internal stress is easily retained inside the extrusion layer structure, leading to cracking during use. Generally, rapid cooling is used for PVC plastic layers. Slow cooling is used to reduce the internal stress of the product. Different temperatures of water are placed in sections in the cooling water tank to gradually cool and shape the product. Slow cooling is used for the extrusion of PE and PP, which involves three stages of cooling: hot water, warm water, and cold water.

Preheating device: Cable core preheating is required for both insulation extrusion and sheath extrusion. For the insulation layer, it is a thin layer of insulation and the presence of pores is not allowed. The wire core can be completely cleaned of surface moisture and oil stains by high-temperature preheating before extrusion. For the extrusion of the sheath, its main function is to dry the cable core and prevent the possibility of air holes in the sheath due to moisture (or moisture from the wrapping layer). Preheating can also prevent the residual internal pressure of rubber during extrusion due to sudden cooling. During the rubber extrusion process, preheating can remove the cold line and enter the high-temperature machine head. The significant temperature difference formed when in contact with the plastic at the mold mouth can avoid fluctuations in plastic temperature and extrusion pressure, thereby stabilizing the extrusion volume and determining the extrusion quality. Electric heating wire core preheating devices are used in the extrusion molding unit, requiring sufficient capacity and determined heating to ensure good preheating and drying rates for the wire core and cable core. The preheating temperature is limited by the wire release speed and is generally similar to the head temperature.

Bubble problem in the cross-section of the insulation layer of the rubber extruder:

1. Excessive temperature control (in the feeding section);

2. Rubber has moisture when it returns to moisture;

3. Long term parking with dissolved rubber not cleaned properly;

4. The geographical environment has high humidity;

5. There is excessive ice or vapor content in the cable core.