A tube manufacturer commissioned the design and installation of a 15-ton semi-automated overhead crane to be used for pickling and dipping applications. Hired to perform the turnkey work was G.W. Becker Inc., Hermitage, Pa.
Equipped with a pair of hoists on a single trolley, the crane is used to lower and raise pipe into and out of a series of dipping tanks. Pipe is manually connected to the hoist, and the bridge is manually traversed over the dip tanks. Then a pair of magnetic proximity switches tell the crane to slow down and stop when it is properly aligned to initiate the dipping process.
Through the use of a ground-based HMI touch screen, the operator selects one of four predefined dipping recipes. If one of the recipes does not meet the dipping specifications, the operator has the option of entering a custom, step-by-step process. Once the recipe has been defined, it is communicated to an onboard PLC via wireless Ethernet, and the trolley is dispatched to execute a specific dipping recipe, advancing from tank to tank.
During the actual dipping process, the load is never disconnected from the crane and it is lowered into the tank at an angle to allow air to escape the pipe. After full immersion is complete, the pipe is brought to a horizontal position (parallel hook centers). When raising a pipe out of a tank, one hoist is initiated prior to the second, providing a hook offset. This offset allows the remaining pickling fluid in the pipe to evacuate when the pipe is completely lifted out of the tank. Before indexing to the next step in the recipe, the crane will wait for a predefined set period of time allowing the dipping fluid in the pipe to drain back into the dipping tank. The hooks are then paralleled and the process continues. Once the dipping process is complete, the crane proceeds to the unload station where parts are removed from the dipping rack. Finally, the crane is put back in queue to repeat the process.
The new crane has increased the company’s daily throughput and reduced labor.
Lift & Access is part of the Catalyst Communications Network publication family.
