Inner and outer ring concentric bearing units and high-precision cylindrical roller bearings for printing presses
Features: The radial bearing of the printing press can realize the bearing arrangement of high radial stiffness and high precision, and is mainly used for the radial support of the main cylinder. The locating bearing series DMF, TBS, TR2 can also accommodate axial forces at the same time. Bearing rings have thick walls and are not interchangeable. Cages are available in plastic, steel or brass. The inner hole of the inner ring has two designs of cylindrical and conical. Generally, double row cylindrical roller bearings have a taper of 1:12, while three or four row cylindrical roller bearings have a taper of 1:30. High-precision cylindrical roller bearings Double-row or four-row high-precision cylindrical roller bearings are of special precision SP or P5 grade, with small cross-sectional height and high radial stiffness, as shown in Figure 1. When used in printing press bearing arrangements, additional housings are usually required. Bearings can only withstand radial forces. These floating bearings are ideal for cylinders that do not move, such as transfer cylinders or plate cylinders in sheetfed offset presses. Design These bearings are usually designed with a conical bore so that the clearance can be precisely adjusted. The rolling elements of the double-row cylindrical roller bearing NN series and the four-row cylindrical roller bearing N4N series are guided by the inner ring rib. The rolling elements of the NNU and N4U series are guided by the outer ring ribs. Internal clearance The standard internal clearance of cylindrical roller bearings NN series and NNU series is C1 class. According to the needs of printing machinery design, we also provide bearings with special clearance. Preloaded high-precision cylindrical roller bearings can be preloaded to eliminate backlash. Lubrication Lubrication is provided through lube grooves and lube holes on the outer ring. Concentric bearing unit with inner and outer rings This type of bearing unit is used for cylinders that do not require radial movement, such as impression cylinders of sheetfed offset presses or newspaper web offset presses. Different from conventional cylindrical roller bearings, the outer ring is thickened. This eliminates the need for bearing housings mounted on printing machines. The bearing arrangement is very economical, and the accuracy is also improved, eliminating the need for the bearing to the bearing seat. Multiple holes in the outer ring are used for positioning and as lubricating inlets and outlets. The outer ring fits tightly into the wall plate hole, so there is absolutely no play at the bearing support. Therefore, the use of printing press bearings can meet very high printing quality requirements. Floating bearing design According to customer's requirements, the inner ring of the bearing has a cylindrical hole or a tapered hole, Figure 2. The tapered hole design can adjust the bearing clearance very accurately, while the straight hole design is very economical and convenient to install. Depending on the load, printing press bearings have two, three or four rows of rolling elements. Bearings can only withstand radial forces. Design of locating bearings For the transfer cylinders of a sheetfed offset press, locating bearings DMF are the best arrangement, Figure 3. It can withstand axial and radial forces and meets very high requirements for rigidity and zero clearance. The double-direction thrust needle roller bearings integrated in this ready-to-install unit are preset with zero clearance and have very high stiffness and very low axial runout. The advantages of achieving excellent print quality are particularly evident in double-diameter cylinders. The inner ring of the double row cylindrical roller bearing has a cylindrical bore. The bearing arrangement is therefore very economical and the installation is simple and safe. Mounted on wall panel via integral flange. This eliminates the need for additional fixings. Internal clearance Internal clearance is specifically defined by the Schaeffler Group. Preloaded bearings DMF and DML normally work with light preload. On request, the bearing DML can also have a small clearance. The bearing unit DML allows a reliable axial displacement of the rotating inner ring relative to the outer ring, even in the preloaded state. Therefore, the bearing DML is very suitable for plate cylinders. Seals are available in open or integrated seal designs. Lubrication This bearing is suitable for oil or grease lubrication, and can also be relubricated through the lubrication hole in the outer ring. The cage has a rib to guide the rolling elements of the printing press bearing. There are plastic cages, steel cages and brass cages. The friction is very small, and the temperature rise is very low under high-speed operation.