slewing bearing soft belt installation skills

The raceway of turntable bearing usually needs heat treatment. The usual process is: forging → roughing → machining → finishing → raceway surface quenching →raceway surface milling and other processes. In the raceway flame surface quenching will form a soft zone. The so-called “soft zone” is the area that has not received the heat treatment. The forming of soft zone is inevitable for the heat treatment. In the last process of heat treatment, due to the relatively large diameters of the raceway of slewing bearings, usually we apply flame surface quenching. This is by using acetylene to heat the surface of the work piece that needs quenching. After the heating, the surface is to be immediately quenched. The heating flame spray gun is installed together with the water spray gun. The tow guns move circularly together at the same time by the circle of the work piece. When the motion is near 360 degrees, stop the heating and cooling immediately. This means there is no overlap in the round area of heating and spraying water. If the overlap occurs in the circular area (the angle of heat treatment on the circle is greater than 360 degrees), a crack in the work piece will occurs. The width of the untreated area along the tangent is generally 15 mm. This 15 mm area is called “ soft zone” in the turntable bearing. Under normal circumstances, when manufacturing the work piece, in the presence of a soft zone, there will be a steel word “S” to mark the specific position of the soft zone. All the normal products have this very important mark. Essentially, the requirement of position of the installation of soft zone is to enhance the service life of the bearing. From the viewpoint of the end-user and the viewpoint of the manufacturer, it’s better to install the soft zone correctly. Therefore, the manufacturer of the slewing bearing should mark the position of the soft zone correctly and exactly. The installer of the slewing bearing should install the soft zone of the slewing bearing accordingly. Because inevitably the soft zone will occurs in the slewing bearings, the user of the turntable bearing has to install the soft zone reasonably in order to enhance the service life of the slewing bearing. Usually, the soft zone should be installed in the minimum loading position. Usually the upper ring soft zone of the rotary device is mounted in a position perpendicular to the projection line of the pitching rotating surface, for example, the upper ring soft zone of the loader or stacking rotary device should be installed in the position perpendicular to the cantilever center line cut over the rotary center, that is, the 90 degree position on the left or right side of the cantilever facing the rotating center. In the usual mechanical design, the soft zone will not bear the maximum force . The mounting position of the lower ring soft zone of the rotary device shall be determined according to the center of gravity of the equipment and the range of the rotation angle. If the angle of rotation is left and right 100 degrees, the maximum center of gravity position above the rotary part is in front, it is recommended to install the lower ring soft zone in the rear, that is, 180 degrees position. If the center of gravity change position above the rotation is equal in the front and back position, the angle position of the lower ring soft zone can be installed arbitrarily.