The feed rate per revolution of the cone die is the reduction amount per revolution, which is the reduction amount of a periodic pattern of rotary rolling. The principle of determining the feed rate per revolution of the cone die should be: on the premise of ensuring that the blank does not have shrinkage folding and fracture, it has high productivity, and makes the plastic deformation of rotary rolling uniform, without deformation defects such as upper mushroom, lower mushroom or pulley shape.
The greater the depth of the plastic deformation zone, the more the upper and lower plastic deformation zones are connected and overlapped, and the more uniform the deformation is. Therefore, the depth of plastic deformation zone can be used as a standard to measure the deformation uniformity of rotary forging. At the same time, the width BB of the plastic deformation zone and the pressure P per unit area on the contact surface are two main factors affecting the depth of the plastic deformation zone. From the slip line drawing of plane deformation, it can be seen that the depth of plastic deformation zone increases with the increase of the width of plastic deformation zone and the pressure per unit area on the contact surface.
As shown in the figure, the active deformation area of the rotary rolling workpiece is the contact area between the cone die and the workpiece, and its width BB is Rx θα Corresponding arc length, and:
Then the relative width of the plastic deformation zone is:
The formula shows the relationship between the feed rate s per revolution and the width BB of the active deformation area, and the relationship curve between the relative feed rate and the relative width of the active deformation area is drawn, as shown in the figure:
By observing the figure, it can be concluded that when s increases, that is, the relative feed rate increases, the relative width BB / RX of the active deformation area increases, and the width BB of the active deformation area increases, so the deformation is more uniform.