Concentric inner and outer ring bearing units and high-precision cylindrical roller bearings for printing machines
Features: Printing press radial bearings can achieve high radial rigidity and high-precision bearing arrangements, and are mainly used for radial support of the main drum. Positioning bearing series DMF, TBS, TR2 can also bear axial force at the same time. The bearing ring walls are thick and not interchangeable. The cage is made of plastic, steel or brass. The inner hole of the inner ring has two designs: cylindrical and conical. Generally, the taper of double-row cylindrical roller bearings is 1:12, and the taper of three-row or four-row cylindrical roller bearings is 1:30. High-precision cylindrical roller bearings Double-row or four-row high-precision cylindrical roller bearings have special precision SP or P5 grades. The section height is small and the radial rigidity is high, as shown in Figure 1. When used in printing press bearing arrangements, additional bearing seats are usually required. The bearing can only bear radial forces. These floating bearings are very suitable for cylinders that do not move, such as the transfer cylinder or plate cylinder of a sheet-fed offset printing machine. Design These bearings are usually designed with a conical bore, so the clearance can be adjusted accurately. 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 ribs of the inner ring. The rolling elements of the NNU series and N4U series are guided by the outer ring ribs. The standard internal clearance of cylindrical roller bearings NN series and NNU series is C1 level. According to the design requirements of printing machinery, we also provide bearings with special clearances. Preloaded high-precision cylindrical roller bearings can be preloaded to eliminate clearance. Lubrication is carried out through the lubricating oil groove and lubricating hole on the outer ring. Inner and outer ring concentric bearing unit This type of bearing unit is used for rollers that do not require radial movement, such as the impression roller of a sheet-fed offset printing machine or a newspaper web offset printing machine. Unlike conventional cylindrical roller bearings, the outer ring adopts a thicker design. In this way, the bearing seat assembled on the printing machine is no longer needed. The bearing arrangement is very economical, the accuracy is also improved, and the matching of the bearing and the bearing seat is omitted. Multiple holes on the outer ring are used for positioning and as lubrication inlets and outlets. The outer ring can be tightly fitted with the wall plate hole, so there is absolutely no clearance at the bearing support. Therefore, the use of printing press bearings can meet very high printing quality requirements. Floating bearing design is based on customer requirements. The inner ring of the bearing has a cylindrical hole or a tapered hole, as shown in 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. The bearing can only bear radial forces. Positioning bearing design For the paper transfer roller of a sheet-fed offset printing machine, the positioning bearing DMF is the best arrangement, as shown in Figure 3. It can bear axial and radial forces and meet the very high requirements for rigidity and zero clearance. The two-way thrust needle roller bearing integrated in this ready-to-use unit is preset to zero clearance, with extremely high rigidity and extremely low axial runout. In double-diameter cylinders, the advantage of achieving excellent printing quality is particularly obvious. The inner ring of the double row cylindrical roller bearing has a cylindrical bore. Therefore, the bearing arrangement is very economical, and the installation is simple and safe. Installed on the wall panel by integral flange. This eliminates the need for additional fasteners. Internal clearance Internal clearance is specifically defined by the Schaeffler Group. Preloaded bearings DMF and DML usually work under light preload. According to requirements, the bearing DML can also have a small clearance. Even in the preloaded state, the bearing unit DML allows the rotating inner ring to have a reliable axial displacement relative to the outer ring. Therefore, the bearing DML is very suitable for printing plate cylinders. The seal provides an open or integrated seal design. Lubrication This bearing is suitable for oil or grease lubrication, and it can also be relubricated through the lubrication hole in the outer ring. The bearing of the printing machine with the retaining frame to guide the rolling element has a plastic cage, a steel cage and a brass cage. The friction is very small, and the temperature rise is very low under high-speed operation.