The product: A de-burring system that removes burrs from hobbed gears. The system consists of drives, robot with grinding tool attachment and brushing stations.
The need: a linear motion system that can handle harsh environment, high load requirements.
The design choice: plain bearings
–Even disbursement of forces for high load handling, versus that of ball bearings.
–Ability to wipe shaft surface clean of dirt and grim during operation.
Advance Design Industries (ADI) in Sheffield Village, Ohio has designed and built custom machine systems for industrial and defense applications for more than 50 years. Their latest problem-solving design, a de-burring system that removes burrs from hobbed gears, was constructed using a series of drive platforms, a robot with grinding tool attachment and brushing stations. Application requirements called for accurate and repeatable positioning with the various stations in many pre-programmed locations. The linear motion parts of the de-burring system had to handle the contaminated environment and heavy loads of the application, 50,000 lb in an industrial machine-tool work area.
The gears are large, 70-120 in. in diameter. Eventually, they will be used as the driving mechanism for crane turntables and wind turbines. The de-burring machine rotates the gear through the robotic grinding station then through each brushing station for a smooth end product.
Three drive platforms as well as the robot and brush stations, riding on a PBC linear bearing system, adjust to the locations for various sizes of geared rings.
The load and environment needs restricted the linear components to plane bearings. These bearings sustain even disbursement of forces. Ball bearings, on the other hand have small points of contact, limiting load handling. Also, ball-bearing systems are more susceptible to vibration and spall shafting under the heavy load. Excess dirt, dust and particulate can collect in the ball cages, which can result in stalling and catastrophic failure.
In addition, the bearings needed to prevent stick-slip, a common problem to bearing systems that are not routinely in motion.
The drive platforms, though important to adjust for different gear sizes, are seldom used for day-to-day functions, so the chosen linear system had to operate with little lubrication, and still move smoothly and reliably when needed.
Simplicity® bearings were chosen for the linear motion system for all stations of the de-burring machine. These FrelonGold® liner-based self-lubricating linear plane bearings require little to no upkeep maintenance, excel in harsh environments and handle heavy load applications. The low friction, self-lubricating system requires no additional grease or oil (as long as application is within design criteria). FrelonGold® has also been shown to handle up to 20x the load of a traditional ball bearing. These bearings wipe all dirt, dust, and grime clean off the shaft.
Simplicity bearing/shafting assemblies were installed into the drive platforms, robot station and brushing station of the system. Testing was conducted over a period of two months with the bearings performing without failure.