31-08-2017, 03:44 PM
The use of robots for friction welding (FSW) poses a number of challenges compared to conventional and rigid FSW machines. However, recent advances in robotics, coupled with new FSW techniques, have substantially increased the potential of robotic TSFs.
An important difference between FSW and fusion welding processes is that FSW is a contact machine operation, which means that there are forces acting between the machine and the welded component. As the tool is pressed into the plastified material, a forging operation is initiated in which the plasticized material is forced to flow around the rotating tool. This requires high machine forces to keep the tool in the material. For FSW of aluminum sheets, the axial force is typically several kilonewtons, depending on the grade and thickness of the alloy. For example, a 3 mm thick aluminum alloy of the 6000 series requires about 5 kN of axial force.
Most industrial robots are articulated arm robots, where the tool is driven by a serial chain of links and typically six rotating joints, driven by electric servomotors. Due to the high force required for FSW, the demands on the machine are high. Therefore, FSW was initially not suitable for implementation in such industrial robots.
A breakthrough came with the development of heavy-duty industrial robots in the late 1990s. Although developed primarily for automotive body lifting in the automotive industry, it was also shown that the robots were suitable actuators for the FSW implementation. In a race for the most powerful robot title among machine manufacturers, payloads increased from a maximum of 500kg around the year 2000 to 1500kg-plus that today's robots are able to lift, with corresponding improvements in accuracy and rigidity. These developments have made industrial robots increasingly suitable for FSW.
Robots have the great advantage of being flexible to reprogram and reconfigure, and to be able to follow three-dimensional articular lines. In addition, industrial robots are often less expensive than comparable five-axis machines, very reliable and well known in many industry segments. This makes them very suitable for high volume industrial applications.
An important difference between FSW and fusion welding processes is that FSW is a contact machine operation, which means that there are forces acting between the machine and the welded component. As the tool is pressed into the plastified material, a forging operation is initiated in which the plasticized material is forced to flow around the rotating tool. This requires high machine forces to keep the tool in the material. For FSW of aluminum sheets, the axial force is typically several kilonewtons, depending on the grade and thickness of the alloy. For example, a 3 mm thick aluminum alloy of the 6000 series requires about 5 kN of axial force.
Most industrial robots are articulated arm robots, where the tool is driven by a serial chain of links and typically six rotating joints, driven by electric servomotors. Due to the high force required for FSW, the demands on the machine are high. Therefore, FSW was initially not suitable for implementation in such industrial robots.
A breakthrough came with the development of heavy-duty industrial robots in the late 1990s. Although developed primarily for automotive body lifting in the automotive industry, it was also shown that the robots were suitable actuators for the FSW implementation. In a race for the most powerful robot title among machine manufacturers, payloads increased from a maximum of 500kg around the year 2000 to 1500kg-plus that today's robots are able to lift, with corresponding improvements in accuracy and rigidity. These developments have made industrial robots increasingly suitable for FSW.
Robots have the great advantage of being flexible to reprogram and reconfigure, and to be able to follow three-dimensional articular lines. In addition, industrial robots are often less expensive than comparable five-axis machines, very reliable and well known in many industry segments. This makes them very suitable for high volume industrial applications.