Gantry System Bridges the Gap Between Conveyor System and AGVs
Lauyans & Company’s customer is a major manufacturer of tires. They have a Gantry Tire Transfer System to move green, uncured truck tires from an Automated Storage / Retrieval System (ASRS) to Automatically Guided Vehicles (AGVs). The AGVs take the green tires into a pressure chamber where, with a combination of pressure and heat, the tread is molded onto the tires and the tire is cured.
An earlier gantry system by another company to handle the tires had problems with reliability and maintenance issues. Lauyans & Company’s new design resolved those issues. The station to handle the tires is designed to pick green truck tires from formed pallets and deposit them onto an adjacent AGV. The station is equipped with two pickup heads. Each pickup head can handle two tires at the same time. Each AGV is designed to handle two tires at a time as well.
The loading cycle begins when two pallets with green tires enter the gantry envelope on a conveyor system. Both pallets are properly positioned on the conveyor to allow for interface with the gantry system. Sensors indicate to the gantry control system when the pallets are present and in position. An AGV which has been dispatched by the Material Handling Control System (MHCS) arrives at the pallet loading station. When the vehicle arrives, it performs an interlock communication with the loader controller. The vehicle sends a signal to notify the loader that it is ready to receive a pair of tires. The vehicle then waits until it receives a signal from the loader that it is clear to enter the load station. Once the vehicle receives the clear to enter signal, it travels to the load point and aligns itself using onboard sensors. The vehicle then signals the loader that it is ready to receive a pair of tires. When the loader receives this signal, it begins the cycle of transferring tires between the conveyor system and the AGV system.
The loaders are furnished with a bar code scanner on each pickup head. These scanners are used to locate and read a bar code label affixed to the side wall of the tire. At the beginning of the load cycle, the robotic loader will extend the gripper mechanisms down inside the bead diameter of the tires on each pallet and lift the tires from their pallets. In the full up position, the gripper mechanism will rotate the tire past its associated scanner to find the location of the label on the tire. The scanner will read the label and transmit the its location and its identification information to the conveyor system PLC. The bar code scan sequence will be tried two times to insure a good read.
When the system signals that the bar code is a good read, the conveyor system controller directs the loader control system to rotate the tires to a pre-determined offset for that tire and to load the tires onto the AGV. If the bar code scan is not successful for either tire, the conveyor system controller will transmit an error message to the loader control system. Both tires will be placed back into their respective pallets for transport to a QA audit area. When the loading cycle is complete, the loader will give the AGV a signal that it is clear to leave. Upon receiving this signal, the vehicle travels to the press which requested the tires. The gripper mechanisms are returned to their home position to await the beginning of the next cycle.
Lauyans & Company’s equipment was designed with simplicity and reliability as essential elements. That included details, for instance, such as coating the Tire End Effector Legs with Teflon so the green tires wouldn’t stick or hang up.
The result was a system that functioned properly and reliably.