Robotic Welding Torches
One vital component of a robotic system is the EOAT. The EOAT is the device that interacts directly with a workpiece, providing the industrial robot with the ability to perform a specific application. The type of EOAT integrated with a robot will depend upon the application type. For robotic welding systems the EOAT used is a welding torch or welding gun.
Welding torches are integrated with industrial robots, allowing the articulated robot to automatically perform a specific welding process. Welding torches are responsible for directing the electrode to the arc, supplying heat to the electrode, and dispensing shielding gas if needed. There are many different types of welding torches and the exact type needed will vary based upon the specific welding application, current, electrode type, and shielding gas.
Robotic welding torches are typically categorized into two groups based upon the cooling method they utilize. The first category is air-cooled torches. Air-cooled torches use ambient air and shielding gas to remove heat from the torch. Air-cooled torches are best for welding applications involving thinner metal workpieces with low-duty cycles and low amperage.
The second category of welding torches are those that are water cooled. Water-cooled torches consist of a radiator system that circulates coolant, ambient air, and shielding gas to remove excess heat from the torch. Water-cooled torches can weld at higher amperages and for longer amounts of time, making them best for the welding of thicker metals.
In addition to the type of cooling method used, torches can also be categorized by their design. Robotic welding torches consist of either a straight barrel or a barrel that is bent. A bent barrel torch is mainly used for robotic arc welding as it provides better workpiece access.
Welding torches can be mounted to six axis robots through either a through-arm configuration or an over-arm configuration. Through-arm torch mounts involve internalizing the torch cables through the robotic wrist and arm. This is becoming the standard torch mounting configuration as many arc welding robots are now designed with hollow arms and wrists for internalized cabling. The FANUC Arcmate 120ic and Yaskawa Motoman MA1440 are both welding robots featuring a hollow arm design. Through-arm mounting extends cable life and increases reliability.
Over-arm torch mounting involves running the torch cabling over the robot arm. This mounting configuration is typically only seen now on older robots, for instance the FANUC Arcmate 120ib. This mounting method can lead to premature cable wear but does allow for easier access to torch cables and better torch positioning for narrow welds.
As mentioned above, there are many different types of torches and the exact type integrated with your robot will depend upon the welding application being automated. Those automating an arc welding application will require a torch capable of TIG, MIG, or FCAW processes. Laser welding robots such as the ABB 4600-20 will need to be integrated with a laser cutter for their torch. Spot welding applications utilize a spot welding gun for the welding torch. Spot welding guns tend to be heavier than other welding torches, so a high payload robot is required. The FANUC R-2000ib/210F is a high payload robot capable of handling the weight of a spot welding gun.