I. Roller

The drum is the main working part of the open mill. It is the part that directly participates in the completion of the rubber mixing work, and has a relatively large impact on the function of the open mill. Therefore, great attention should be paid to the design, manufacture and use of the roller.

1. Material and technical requirements

The basic requirements for the roll of the open mill are: sufficient mechanical strength and rigidity to ensure that the roll is not damaged during normal use; the working surface of the roll should have high hardness, wear resistance, resistance to Chemical corrosiveness and resistance to falling off, avoid being damaged by the rubber cutter and corroded by some compounding agents when cutting glue; have a reasonable geometry to eliminate local stress concentration as much as possible; have good thermal conductivity, so as to facilitate Heating and cooling of the compound.

The material of the roller is generally chilled cast iron. It is characterized by hard outer layer, good internal toughness, high strength, wear resistance and corrosion resistance, good thermal conductivity, simple production and low cost. The rollers of the small-scale open mill used in the experiment are also made of medium carbon alloy steel.

2. Structure and size of each part

Because of the different uses of the open mill, the working appearance of the rollers is also different. The rollers used for plasticizing, kneading, hot refining and sheet pressing are all lubricated; the rollers used for breaking, washing and destroying are mostly special grooves with grooves, and the rollers used for refining are Lubricate the belt drum.

There are two types of roller structures, one is a hollow structure and the other is a circular drilling structure.

Second, roller bearings

The roller bearing of the open mill bears a large load (for example, the φ650*2100mm open mill has a relatively large load of 1960KN), and the sliding speed is low and the temperature is high. Therefore, the bearing is required to be wear-resistant, strong bearing capacity, long service life, and convenient to manufacture and install.

The roller bearing mainly adopts two kinds of structures: sliding bearing and rolling bearing.

1. Sliding bearings

This is a widely used type of roller bearings for open mills. It is characterized by simple structure, convenient manufacture and low cost. The lubricant of the sliding bearing is dry butter or thin oil. The bearing body material of the sliding bearing is made of cast iron or cast steel, and its tensile strength is not less than 200Mpa, generally HT200 cast iron; the bushing is made of metal (bronze) or non-metal (MC nylon). The disadvantage of nylon bushing is poor thermal conductivity and large thermal expansion.

2. Rolling bearings

In recent years, double row roller bearings have been used in large open mills. Its characteristics are long service life, small friction loss, energy saving, convenient installation, simple maintenance, and the consumption of lubricating oil can be reduced by 75% compared with ordinary sliding bearings. But the cost is high, the matching is difficult, and the use is less.