Eight Tonnes Load Driven Into Oven by Compact Linear Chain
Aluminium engine blocks can develop residual stresses due to differential cooling during the casting process. This can cause the distortion of critical features during machining and make it difficult to maintain dimensional tolerances. To remove these stresses, many manufacturers heat treat their cast engine blocks prior to machining, a process that effectively relaxes the metal.
It is for this purpose that the Aerotherm Group was commissioned by Ryobi Aluminium Castings in Northern Ireland to design and produce a stress relieving oven. Essential to the design of this system is the mechanism which pushes the carriage or skillet of engine blocks into the oven for heat treatment and out again at the end of the four hour cycle.
With a static load of 8 tonnes the chosen push/pull mechanism needed to be exceptionally strong and withstand high temperatures without substantially increasing the footprint of the overall system. The Framo Morat range of products was a clear front runner given these parameters, resulting in Aerotherm working with the UK distributor R. A. Rodriguez on the design and specification of the optimal mechanism.
Two Framo Morat products combine to provide the ideal solution for this application. They are a Framo 60PSG Linear Chain which is driven by an AG160 Compacta geared motor. A Framo Chain guide was also supplied by R. A. Rodriguez and shipped separately for early installation on the factory floor.
The design of the precision chain links on the Linear Chain enables it to push as well as pull heavy loads. Their special profile, with interlocking fingers at one end, enables the chain to roll up for efficient storage in one direction and form a rigid thrust device in the other.
In the magazine the chain is stored spirally within a narrow chamber making it ideal for the Ryobi application where space is limited but the maximum stroke is long at 6.5m. The device provides high positioning accuracy, constant stroke speed and shock-free motion.
As standard, the chain can easily withstand the oven temperature of 250◦C required by this application but Framo Morat also supply a high temperature chain option suitable for temperatures up to 560◦C.
For the oven loading/unloading mechanism the Framo Linear Chain is complemented by the equally neat Framo Compacta slip-on geared motor. This product is significantly lighter in weight than its competitors but provides the same output torque and speed. Compacta’s economical dimensions are achieved through the use of a spur and worm gear transmission combined with performance-optimising motors.
“The Linear Chain system on the stress relieving oven at Ryobi is working very well,” confirmed Aerotherm’s Dave Taylor. “And with the help of R. A. Rodriguez we have also been able to retrofit a higher powered motor to the Compacta that enables the system to drive the 8 tonnes load at a greater speed of 50mm/sec.”