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|Material:||Stainless Steel||Surface Covered Material:||Rubber|
Rubber Covered Paper Machine Rolls,
20KN/M Paper Machine Rolls,
Vacuum Jumbo Paper Machine Rolls
rubber covered Vacuum jumbo Press Roll For High Speed craft liner Paper Making Machine
Vacuum press rolls are mostly used in medium and high speed paper machines. The upper pressing roller of the vacuum pressing roller is a stone roller, and the lower pressing roller is a vacuum pressing roller. The vacuum press roll is located in the four-roll three-nip zone of the paper machine. Its structure is basically the same as that of the vacuum roll and suction roll. The roll shell is made of bronze or stainless steel. The thickness of the roll shell is determined by the required rigidity and strength. Other working parameters of the paper machine, such as vehicle speed and vacuum degree, remain unchanged. The thicker the roll shell, the smaller the dehydration capacity. In high-speed papermaking, after the moisture of the blanket and wet paper is sucked out, it passes through the eyeholes on the roller, and then passes through the vacuum suction area almost before reaching the vacuum chamber, and then is thrown into the white water tray by the centrifugal force of the roller. The function of the vacuum chamber is only to suck the air in the shell holes. The thicker the roll shell, the more air volume is sucked. Therefore, the use of high-strength metal to make a vacuum press roll with a thin roll shell is beneficial to improve the efficiency of press dehydration.
The vacuum press roll can remove more water from the wet paper. Compared with the ordinary press, it can improve the dryness of the paper. The paper web is also less crushed. The dehydration is more uniform along the width of the banner. The felt is more stable and good. status. However, the vacuum press roll also has its shortcomings. For example, the strength of the roll body is weakened, the structure becomes complicated, the power consumption is increased due to the need to vacuum, and noise pollution is generated, and hole marks may appear on the surface of some paper types.
The bearings used in the transmission of the vacuum press rolls are generally double-row spherical roller bearings, which are directly matched with the shaft after hot mounting. According to the appearance analysis of various wear conditions, the following reasons for wear are summarized:
(1) The bearing position of the press roll has a high working temperature. In normal production and operation, the bearing is in a sealed environment and the normal operating temperature is relatively high. Each component of the bearing will be heated and expand, making it easier for materials to invade and adhere, causing the rolling elements of the bearing to run The increase in resistance causes small pits or pit-like peeling on the surface of the rolling elements, and the peeled metal will adhere to the surface of the raceway and cause the surface of the raceway to be rough.
(2) When the vacuum press roller absorbs the moisture of the paper, the humidity is large, and the splashed paper lint during the production of poor sealing will invade the bearing and cannot be removed. The entry into the ball will reduce the lubrication effect of the bearing and increase the running resistance of the roller to rub the inner ring. , So that the inner ring is heated to expand and there is a gap, causing wear.
(3) Due to the long-term operation of the equipment, the bearings and bearing positions have a certain degree of fatigue deformation due to the characteristics of the metal itself. The interference of the bearing inner ring during installation cannot be guaranteed, and the pre-tightening force is insufficient, resulting in the relative rotation of the bearing inner ring. Cause the bearing position to wear.
The width of the vacuum chamber of the vacuum press roll is narrower, usually 100, and the diameter of the small holes on the surface of the vacuum press roll is about 4.5mm.
The opening rate of the vacuum press roll surface is relatively low, generally 15%~25%. The surface of the vacuum squeeze roller needs to be rubberized, and the thickness of the rubber layer is 20~. The shell of the vacuum roll is made of tin bronze or stainless steel by centrifugal casting. The line pressure of the equipment will vary according to the moisture of the wet paper, the quantitative and type of the paper, the strength of the roll shell, etc., generally 20~50KN/ m.
The vacuum press roll can remove more water from the wet paper, which will increase the dryness of the paper compared with the ordinary press, the paper web is also less crushed, the dehydration along the width of the banner is more uniform, and the felt can be more maintained Stable and good condition.
The layout of the general vacuum press roll and its ancillary equipment is similar to that of the general press. The eccentric direction of the vacuum press is opposite to that of the general press, that is, the upper press roll is offset from the lower roll by 50-60mm in the paper output direction. In order to remove the moisture in the nip, the suction port of the vacuum box in the vacuum roll must face the paper feed side of the nip. This is the only way to make the felt and the wet paper web contact the vacuum roll first to achieve the sealing effect on the suction opening of the vacuum box. This can effectively prevent outside air from entering the vacuum system to a certain extent. For this reason, the blanket generally enters the nip in a downward horizontal direction, and then leaves the nip in a downward horizontal direction, which is the so-called low-in-low Out
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