The slewing bearing device includes various slewing bearings, rotary raceways, and the like. Its role is to support a heavier mechanism around a certain center of rotation.
The raceway of the slewing bearing device generally needs heat treatment processing. The usual processes are: forging → roughing → quenching and tempering → finishing → surface quenching of the raceway surface → roller surface grinding and other processes. The flame surface quenching on the raceway surface will form a soft band. Soft zones are areas that have not been heat treated. The formation of soft tape is necessary for the heat treatment process. In the final heat treatment process, due to the large diameter of the slewing bearing's raceway circle, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece that needs to be hardened and then add water to cool. This process is continuously completed. The heated flame spray gun and the water gun are mounted together while making a circular motion along the circle of the workpiece. Stop heating and spray water as soon as you move close to 360 degrees. That is, there is no overlap between the heated and sprayed circular regions. If there is an overlap between the heating and the circular area where the water is sprayed (heat treatment occurs at a circle with an angle greater than 360 degrees), the workpiece will crack. The width of the non-heat treated area in the tangential direction is generally 15 mm. This 15 mm area is called a flexible belt in a slewing bearing. It often becomes a Soft Zone in English. Under normal circumstances, the word "S" is used to describe the specific soft-spot position on the part where the soft-spot is present. Imported or domestically produced regular products usually have this very important mark. The requirement for the installation of the flexible tape is essentially to improve the life of the bearing. It is also reasonable from the perspective of the user and the manufacturer to install the upper and lower rings of the slewing ring. Therefore, as a slewing bearing manufacturer should accurately mark the soft-slewing position of the slewing ring as a manufacturer and installer should install the soft-sleeve position of the slewing ring as required.
Because of the inevitability of the soft belt on the slewing bearing device, it is required that the user who uses and selects the slewing bearing device should reasonably install the position of the flexible belt so as to increase the service life of the bearing. The general principle is to try to install the flexible belt in the position where the soft belt carries the least pressure during the load change. Usually, the upper loop soft belt of the rotary device is installed at a position perpendicular to the projection line of the pitch plane. For example, the upper loop soft belt of the shipper or the stacker-reclaimer rotary device is installed at a position perpendicular to the centerline of the boom and cut through the center of the rotary. , standing on the center of the slewing center 90 degrees to the right or left of the cantilever. In a typical mechanical design, the flexible belt does not have the most stressed state of the support roller of the slewing bearing at this position. The installation position of the lower loop flexible belt of the rotary device shall be determined according to the center of gravity of the device and the range of the rotary angle. If the angle of rotation is about 100 degrees left and right, and the maximum center of gravity of the part above the turn is at the front, it is recommended that the lower belt should be installed at the rear, ie, 180 degrees. If the position of the center of gravity of the part above the turn is the same in the front and rear positions, the angle of the lower band can be arbitrarily installed.
