Multi-Layer Rubber Calendering Line Is Used To Produce Rubber Sheets And Rubber Conveyor Belts

What industries are calenders used in?

 

The calender is an important equipment in the rubber processing process. It is mainly used to make the mixed rubber into a film of a certain thickness and width or to bond the film with fabrics (such as cords, canvas, etc.), steel wire and other skeleton materials. The following are some rubber products that use calenders:
1. Tire
Tire
In the production of tire casings, the calender plays a key role. First, it is used to manufacture various components of the tire casing. For example, the calender can be used to calender the rubber compound into tread rubber. The tread rubber is the part of the tire that contacts the ground. Its thickness and surface quality are crucial to the tire's wear resistance, grip and other performance.
At the same time, the calender is also used to bond the cord (a cord-like fabric made of fibers) and the rubber compound. The cord plays a reinforcing role in the tire and can withstand various stresses during the tire's driving process. The calender evenly covers the rubber on the surface of the cord to form structures such as the belt layer and the carcass cord layer, which can ensure the strength and stability of the tire.
Inner tube
For the production of inner tube, the calender can calender the inner tube rubber into a film of uniform thickness. The thickness requirements of the inner tube are relatively strict. Too thick will increase the weight and rolling resistance of the tire, and too thin will easily cause problems such as air leakage. The calender can accurately control the thickness of the inner tube film to ensure the quality of the inner tube.
2. Conveyor belt
Ordinary conveyor belt
The rubber covering layer of the conveyor belt is processed by a calender. For example, when producing ordinary conveyor belts for conveying materials such as coal and ore, the rubber compound needs to be calendered into upper and lower covering layers of a certain thickness, covering the canvas skeleton of the conveyor belt. The calender can make the rubber covering layer fit tightly with the canvas, ensuring that the rubber will not easily peel off during the long-term operation of the conveyor belt, and at the same time give the conveyor belt good wear resistance, tear resistance and other properties.
Special conveyor belt
For some conveyor belts with special requirements, such as food-grade conveyor belts (used for conveying food, etc.), the calender can calender the rubber material that meets food hygiene standards into a uniform and smooth surface. The surface of this conveyor belt cannot have impurities and rough textures to avoid contaminating food. There are also high-temperature resistant conveyor belts. The calender can make high-temperature resistant rubber compounds into corresponding components to ensure that the conveyor belt can work normally in a high-temperature environment.
3. Hose
Wire braided hose
In the production of wire braided hoses, the calender is used to make the inner and outer rubber layers of the hose. The inner rubber layer needs to fit tightly inside the wire braided layer to provide a sealed environment for the conveyed medium. The outer rubber layer protects the hose and enables it to resist external wear and corrosion. The calender can make the thickness of the inner and outer rubber layers of the hose uniform, ensuring the quality and service life of the hose.
Fiber-wound hose
For fiber-wound hoses, the calender is also used to make the rubber layer of the hose. It calenders the rubber compound into a suitable thickness, and some functional additives such as anti-aging agents, flame retardants, etc. can be added to the rubber compound to meet the needs of the hose in different application scenarios. When combined with the fiber winding layer, the calender can make the rubber and the fiber fit well and enhance the overall performance of the hose.
4. Rubber sealing products (such as rubber sealing rings)
O-type sealing rings
When producing O-type sealing rings, the calender can calender the rubber compound into thin sheets, and then make O-type sealing rings through subsequent molding processes (such as cutting, vulcanization, etc.). The calendering process can ensure the density and uniformity of the rubber material, so that the sealing ring has good sealing performance during use and can effectively prevent the leakage of liquid or gas.
Seals of other shapes
For rubber seals of other shapes such as square and rectangular shapes, the calender can also first make the rubber into a film of appropriate thickness to provide basic materials for subsequent molding processing. In addition, the calender can also add some reinforcing materials or filling materials to the rubber film to improve the hardness, strength and other properties of the seal to meet different sealing requirements.
 

Working principle of rubber calender:
The calender mainly extrude and stretch rubber and other materials through a series of rollers to achieve the processing purpose.
1. Basic structure and roller configuration
The calender usually has multiple rollers, usually two, three or four rollers. These rollers are arranged horizontally or at a certain angle. For example, in a three-roll calender, there are upper rollers, middle rollers and lower rollers. The diameter and length of each roller vary according to the purpose of the calender and the scale of the processed material. The rollers are generally made of chilled cast iron or alloy steel, and the surface is processed and ground with high precision to ensure its cylindricity and surface finish, as this will directly affect the quality of the calendered product.
The gap between adjacent rollers is adjustable, which is a key factor in controlling the thickness of the calendered product. The gap size is accurately adjusted by mechanical or hydraulic devices to adapt to the calendering of materials with different thickness requirements.
2. Material transportation and deformation during work
When the rubber material (usually the rubber material after mixing) is fed between the rollers of the calender, the rotation of the rollers drives the rubber material forward. For example, in a double-roll calender, the two rollers rotate in opposite directions, and the rubber is rolled into the gap between the rollers under the action of friction. As the rollers continue to rotate, the rubber is squeezed by the rollers. Since the gap between the rollers is smaller than the original thickness of the rubber, the rubber is gradually thinned when passing through the gap, and the width will also expand according to the shape and arrangement of the rollers.
In this process, the molecular chains inside the rubber will be oriented along the calendering direction. This orientation of molecular chains has a great influence on the physical properties of the calendered products, such as improving the tensile strength and tear resistance of the material, but if the orientation is excessive, it may also cause anisotropy, making the product weaker in some directions.
3. Work in conjunction with other auxiliary devices
The calender is usually also equipped with a feeding device to evenly convey the rubber between the rollers. The feeding device can control the feeding speed and feeding amount of the rubber to ensure the stability of the calendering process. At the same time, there is a traction device at the discharge end of the roller, which is used to pull the calendered material out at an appropriate speed to prevent the material from accumulating or over-stretching at the roller.
In order to ensure the quality of calendered products, some calenders are also equipped with temperature control systems. Because the physical properties of rubber materials such as viscosity are affected by temperature, by controlling the temperature of the rollers, the fluidity of the rubber can be adjusted, so that the rubber deforms more evenly during the calendering process, thereby obtaining products with more stable thickness and quality. For example, when processing some high-hardness rubbers, appropriately increasing the roller temperature can reduce the hardness of the rubber, making it easier to be calendered.
 

Detailed specification: