How is the slewing bearing soft zone produced?
How is the slewing bearing soft zone produced?
The raceway of the slewing bearing generally needs to be heat treated. In the heat treatment process, because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it. , this process is completed continuously.
1. How is the slewing bearing soft zone produced?
During the production and processing of the slewing bearing, the raceway of the device generally needs to be heat treated. The usual processes are: forging → rough machining → quenching and tempering treatment → finishing → raceway surface flame surface quenching → raceway surface grinding and other processes . One of the raceway surfaces is flame quenched to form a soft zone.
The so-called soft zone is the area that has not been heat treated. The formation of the soft zone is necessary for the heat treatment process. In the heat treatment process of the slewing bearing, because the diameter of the raceway circle of the slewing bearing is relatively large, flame surface quenching is usually used. The method is to use acetylene to heat the surface of the workpiece to be hardened and then add water to cool it.
The heating flame spray gun and the water gun are installed together and make a circular motion along the circle of the workpiece. When the movement is close to 360 degrees, the heating and water spray are stopped immediately. That is, the circular areas of heating and water spray do not overlap. Cracks in the workpiece can occur if the circle areas where the heating and water spray occur overlap (heat treatment at an angle greater than 360 degrees on the circle). The tangential width of the unheated area is typically 15 mm. This 15 mm area is called the soft zone in the slewing bearing, that is, the so-called soft zone is the area without heat treatment. The formation of the soft zone is essential to the heat treatment process.
Under normal circumstances, the steel character "S" is marked on the position where the soft zone exists in the workpiece to indicate the specific soft zone position. The installation position of the soft bzone is essentially to improve the life of the bearing. From the perspective of the user and the manufacturer, it is still a reasonable position to install the upper and lower ring soft zone of the slewing bearing. Therefore, the manufacturer of the slewing bearing should accurately mark the position of the soft belt of the slewing bearing, and the manufacturer and installer should reasonably install the position of the soft zone of the slewing bearing as needed.
2. the installation position of the soft zone
Usually the upper loop soft zone of the slewing device is installed at a position perpendicular to the projection line of the pitching rotation plane. For example, the upper loop soft zone of the slewing device of a ship loader or stacker-reclaimer should be installed at a position perpendicular to the center line of the cantilever and cut through the center of rotation , that is, standing at a 90-degree position facing the left or right side of the cantilever on the center of rotation. In the usual mechanical design, the soft zone does not have the stress state of the support roller of the slewing bearing device at this position. The installation position of the lower ring soft zone of the slewing device should be determined according to the center of gravity of the equipment and the range of the slewing angle. If the rotation angle is 100 degrees left and right, and the center of gravity of the upper part of the rotation is in the front, it is recommended to install the lower ring soft zone at the rear, that is, at a position of 180 degrees. If the change position of the center of gravity of the upper part of the rotation is the same in the front and rear positions, the angular position of the lower ring soft zone can be installed arbitrarily.
Because of the inevitability of the soft zone on the slewing bearing device, it is required that the user who uses and selects the slewing bearing device should install the position of the soft zone reasonably to improve the service life of the bearing. The general principle is to try to install the soft zone in a position where the soft zone is under less pressure during the load change.
