TPT May 2024

ARTICLE

Fronius

Teaching gripping and depositing The conventional handling sequence itself – picking up the pallet, positioning it for welding, transporting it back and depositing it – is a standard program and requires no intervention from the operator. This is referred to in the field as an “encapsulated” function. Only the gripping positions have to be specified. If a new component is “moved in” and not recognised by one of the depositing or receiving stations, the automatic run pauses. The welding specialist is prompted to start a teaching process with the robot controller – the Fanuc iPendant – and receives step-by-step instructions from the system software. Based on this, the system “learns” the required gripping/depositing position for the relevant station (eg for the clipboard). This position is stored in a register and is available for the handling process from that point on. The automatic run can then continue to the next station. If the component is also unknown there, this position must also be taught. Once all the stations have been worked through as described, the handling robot transports all other identical components through the system automatically, without interruption. If a pallet should have seven components but there are only three components on it, this is no issue for the system. It detects an “empty grip” and automatically moves to the next component position. Custom-made teach pallet In addition to the standard offset assignment, which favours simple component shapes, Anton Paar wanted to be able to deposit up to 30 metal components at any point on a pallet. Fronius responded by creating the “Teach pallet” function. Selecting this function makes it possible to separately teach the position of each component on the pallet. “These two versions, offset and teach pallet, offer us maximum flexibility in component placement,” explained Dr Ingo Riemenschneider, department manager for production automation. “It doesn’t always make sense for us to define component positions using offset distances. We have to fix some components in different orientations because of their complex shapes.” As precise as on the first day When the welding specialists want to start a welding process, they use their handheld scanner to scan the item number on the component data sheet. “If the system detects the item number and thus the component, it knows about the handling and welding process and starts operation. Everything is controlled via the HMI T21 RS. The system stores which gripper and which device are needed for each of the components,” explained Dr Riemenschneider. “The same applies to the argon flushing time during forming and the seam time. The system also knows whether and what data is required for process data recording.”

TIG welding is performed on so-called main carriers; handling robot positions the pallet with components

For example, an offset might be 200mm on the y-coordinate and +200mm on the x-coordinate. The pallets manufactured by Anton Paar consist of perforated plates that are centimetres thick and function as a plug-in system. They are located in a pallet store consisting of two racks and are designed to accommodate each of the different workpieces, with the receiving and depositing positions of individual components often varying depending on the nature of the component and the gripper of the handling robot. The robot controller contains a hierarchically superordinate robot program for each workflow type. This is where the welding programs created with Pathfinder are stored. If a pallet for Workflow 2 is created on the HMI (components are welded directly on the pallet), the robot controller filters the corresponding robot welding programs and Anton Paar’s welding specialist can conveniently choose between all the programs that are available for Workflow 2 and assign the right one to the pallet. There is also the option to not only use a single welding program but also create an entire work sequence. For example, a TIG program can be created for a pallet, followed by a MAG program (eg CMT) in the same sequence. In this case, the robotic welding system would execute both programs one after the other and automatically change the welding process. In addition, the experts at Anton Paar can insert certain special steps into the HMI process. For instance, the system knows the special “Turn component” step, which can be used between the two welding processes (TIG and CMT) if necessary. If a specific gripper is required for pallet handling, as described in Workflow 1, the system operator must select it

in the system. As previously mentioned, there are a total of six different grippers available, all of which are kept in a gripper station.

Pallet storage with components and clamping devices

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MAY 2024