Mechanical rolling is a surface finishing method which doesn’t involve the removal of shavings/chippings, but rather works through plastic deformation. This process is used to improve the resistance of a surface.
During the rolling process, various rollers are forced against the surface, creating a pressure which generates plastic deformation. This pressure creates a flattening of the ridges and a filling of the depressions on the surface of the piece, increasing its hardness and density.
The rolling process obtains very low roughness levels, which are generally not achievable through cutting methods (from Ra 0,8 to Ra 0,2). The rolled surfaces thus present an improved resistance to wear and fatigue-induced breaking.
In the case of the rolling of grooves, the process is achieved through the rotating movement of dedicated rollers which transfer their imprint on the finished piece. This is made possible thanks to specific devices which are very narrow, and thus capable of entering even the smallest of grooves.
The application of the rolling technology in the production of transmission shafts is fundamental to give the surface a better rugosity level compared to turning, and at a lower cost compared to grinding. Furthermore, rolling also increases surface hardness, which is ideal for surfaces meant for guide shoe or gasket sliding.
As rolling is a plastic deformation process which doesn’t involve the removal of shavings, it’s important that the surface to be rolled is adequately prepared through a turning process first.
Pressure rolling has application in a wide array of markets:
- Automotive, for the production of steering shafts, motion transmission shafts, gears and drive shafts.
- Oil and gas, for the production of valve shafts, components for trunnion ball valves, throttle/butterfly valves, gate valves, valve automation, components for rotary pneumatic actuators 90° 180° 270°, electric rotary actuators, actuated valves.
- Energy, production of transmission shafts for wind turbines, turbines in general and motion transmission devices.
- Mechanical industry, for the production of gears for adaptors, endless screws for compressors, pinion shafts for gearboxes.
Here at Mecal srl, we apply the rolling method to the guide shoe and O-ring gasket sites of pinions for pneumatic rotary actuators.
Whether they’re made out of carbon steel or inox steel, the location sites of the shafts produced by our rolling process reach very low roughness (Ra 0,2/0,6) and higher surface hardness compared to the removal of shavings.
Increasing surface hardness while also decreasing rugosity leads to a decrease in friction between the sliding surface of the transmission shaft and components such as O-ring gaskets and guide shoes.
We use the same technique for pinions for Scotch-Yoke actuators, even though they often do not present guide shoe or gasket sites. This is done in order to give the rolling surfaces the same characteristics as those of pinions for Rack and Pinion actuators.
Here are the advantages that the rolling of pinions gives to the finished rotary pneumatic actuator, in contrast to the sole shaving-removal process:
- ● Less resistance to the rolling between elements.
- ● Less wear of plastic elements such as gaskets and guide shoes.
- ● Less power necessary to the rotary pneumatic actuator in order to rotate.
- ● Increased lifetime of the rotary pneumatic actuator.
- ● Improved maintenance intervals of the rotary pneumatic actuator.