Rolling process

Calendering is a process in which the mixed rubber is made into film on the calendering machine or made into semi-finished fabric with the skeleton material. It includes sheet pressing, laminating, pressing and textile hanging glue and other operations.

The main equipment of calender is calender, which is generally composed of working roller, frame, frame, transmission device, speed regulation and distance adjustment device, roller heating and cooling device, lubrication system and emergency stop device. There are many kinds of calender, the work roller has two, three, four, the arrangement of the two roller vertical and horizontal; The three rollers are upright, γ and triangle; The four rollers are γ, L, Z and S. According to the purpose of the process is divided into the main sheet calender (used for calendering film or textile paste, most of the three or four rolls, the plastic degree of each roll is different), rubbing calender (used for rubbing textiles, three rolls, each roll has a certain speed ratio, roller speed is large. With the help of speed ratio rubbing into textiles), universal calender (also known as universal calender, both tablet pressing and rubbing function, three or four rolls, adjustable speed ratio), press calender, fit calender and steel wire calender.

Calendering process generally includes the following processes: preheating and glue supply of mixed rubber; Opening and drying of textiles (and sometimes dipping) the cooling, winding, cutting and placing of semi-finished products on a four - or three-roller calender or hanging glue on a textile.

Before calendering, it is necessary to pre-process the rubber material and textiles. Before the rubber material enters the calendering machine, it is necessary to turn it over in the thermal mixer. This process is called thermal refining or preheating, which aims to improve the mixing uniformity of the rubber material, further increase the plasticity, improve the temperature and increase the plasticity. In order to improve the adhesive properties of rubber and textile and ensure the calendering quality, it is necessary to dry the fabric, the moisture content is controlled at 1-2%, the water content is low, the fabric becomes hard, easy to be damaged in the compression, the water content is high and the adhesion is poor.

Calendering performance of several common rubber natural rubber thermoplastic shape, small shrinkage rate, easy calendering, easy adhesion hot roller, roller temperature difference should be controlled, so that the film smooth transfer; Styrene butadiene rubber has small thermoplasticity and large shrinkage, so the rubber material used for calendering should be fully plasticized. Because the thermal sensitivity of styrene butadiene rubber to calendering is very significant, the calendering temperature should be lower than natural rubber, the temperature difference of each roller is high to low; Chloroprene rubber in 75-95℃ sticky roll, difficult to calendering, should use low temperature method or high temperature method, calendering to fast cooling, paraffin wax, hard ester acid can reduce the phenomenon of sticky roll; Ethylene-propylene rubber has good calendering performance and can be operated continuously in a wide temperature range. When the temperature is too low, the rubber material has large shrinkage and is easy to produce bubbles. Nitrile rubber has small thermoplastic property and large shrinkage. Adding filler or softening agent in rubber material can reduce shrinkage rate. When the filler weight accounts for more than 50% of the weight of raw rubber, the film with smooth surface can be obtained.

Drawing process,

Pressing out process is through pressing out machine cylinder wall and the role of screw parts, so that the rubber material to achieve the purpose of extrusion and preliminary modeling, pressing out process has also become the extrusion process.

The main equipment of the pressing process is the pressing machine.

Several rubber rubber pressing characteristics: natural rubber pressing speed, small shrinkage of semi-finished products. Body temperature 50-60℃, nose 70-80℃, mouth 80-90℃; Styrene butadiene rubber pressing speed is slow, compression deformation is large, the surface is rough, body temperature 50-70℃, nose temperature 70-80℃, mouth temperature 100-105℃; Neoprene rubber is not fully heated before pressing out, the body temperature is 50℃, the nose is 70℃, the mouth type is 70℃; Ethylene-propylene rubber pressing speed, small shrinkage, body temperature 60-70℃, nose temperature 80-130℃, mouth 90-140℃. Nitrile butadiene rubber pressing performance is poor, pressing should be fully hot refining. Fuselage temperature 50-60 ℃, nose temperature 70-80℃.