FANU robots increase the economy of welding operations

The use of industrial robots is now a trend because the use of stand-alone and responsive systems can increase productivity and reduce the cost per part of the product. Welding is carried out by an automation device connected to a separate Ethercat computer-aided robot, which increases the economy of welding work.

ARC of Houston, Texas, United States, is a specialist in welding and cutting equipment with 90% of its products used in the oil and gas industry and used by customers around the world. ARC's automated welding and cutting units use standard computer-aided design technology that is widely available in the market to ensure long-term use. On the other hand, when it comes to selecting the control devices for the equipment, ARC companies use disconnected control systems for the vast majority of their competitive needs. The reason for this is that the control system is a unique design that rarely causes problems during the subsequent maintenance phase, and ARC is convinced of this.

Automation is suitable for rapid plasma welding

For a long time, countless ARC users have been using the company's plasma welding equipment. Plasma welding is economical compared to laser welding, but the disadvantage is that laser welding alone does not meet the requirements in a short welding cycle time. The reason for this is that although the welding quality is high with conventional plasma welding equipment, plasma welding is very slow compared to the use of laser welding equipment, and a high heat input is required during the operation.

FANU robots increase the economy of welding operations

Fig.1 The ARC-11-RB welding robot is an automated welding robot for assembly and liquid cleaning equipment

In order to improve the efficiency of plasma welding, ARC has developed a new welding method in its own laboratory, the triple pulse welding method. This new welding method is based on the well-known tungsten inert gas welding method. The basic idea of the triple pulse welding method is based on the use of three different intensities of electric currents in order to achieve a high heat transfer rate with a weak heat energy generated. Using this method, plasma welding devices can achieve similar welding efficiency to laser welding devices, and at the same time be economical.

Commissioned by a major user in Texas, ARC developed the ARC-11 RB automated welding robot for the installation of liquid cleaning equipment (Figure 1). For this purpose, the triple pulse welding system was integrated for the first time. The ARC-11 RB automated welding robot is equipped with a Beckhoff CX1010 embedded PC and a Twincat NC PTP control unit (Fig. 2) with Windows XP software. The compact embedded PC is housed in a box and is used to control the entire welding unit, including the gantry crane in the workshop, the robot functions, the operating face, the induction heating components, the welding workpiece handling unit and all components that work with compressed air.

Fig. 2 Beckhoff's CX1010 embedded PC with Twincat NC PTP software controls the entire welding process of the ARC-11-RB

Thanks to the above-mentioned technology, the entire welding operation process is accelerated and the various steps of the entire welding operation are automated. The entire welding process is carried out by a gantry crane in the workshop that lifts and cuts the tubes to a nominal length and feeds them into a tensioning device (Fig. 3). At the same time, the welding robot picks up an end ring from the conveyor belt and places it inside a second set of tie rods to position itself (Fig. 4). The robot changes the workpiece gripping device against the torch and welds the end ring to the tube together (Figs. 5 and Fig. 6). After that, the two tensioners are automatically opened, and the gantry crane takes out the finished welded workpiece at one end. Then the tube is rotated 180°, the other end of the tube is placed into the tensioner, and the welding procedure is repeated. When the welding workpiece is finished at the other end, the gantry crane transports the pipe that has completed the welding operation to a storage rack. Depending on the dimensions of the workpiece, the duration of this welding operation is up to 2 minutes.

The Fanuc Arcmate M 710i C-50 robot is controlled by a CX1010 embedded PC from Beckhoff (Figure 7). The Powerwave R350 Lincoln welded current power supply is used, which is seamlessly connected directly to the Beckhoff embedded PC via a Devicenet main integrated circuit assembly. The Ethercat clamps act as an I/O system and are sequentially arranged directly on the CX1010 Beckhoff Embedded PC. In cases where the power supply via the Devicenet interface is not required for welding work, or when the reaction time is extremely short, the ARC welding unit uses the EL403x analog Ethercat output clamp.

The function of the welding robot device is realized on the PC-CPU

According to the requirements of industrial control, ARC designed its own visualization software for the controller interface of the welding robot. By using this software, the welding operator will be able to operate the welding robot in a more comfortable environment than the Windows-PC window, which is the same as the Windows-PC window. Twincat ADS connects the controller interface with the control unit. The Twincat Motion Converter integrates the control of the welding robot into the Twincat automation group.

The Twincat motion picture converter is transparently integrated into the existing conveyor control range: Robotics and conveyor control functions are optimised in sync with Twincat NC PTP (point-to-point positioning of axes) or NC I (positioning of axes inserted in 3D images). All NC properties, such as "curve runners" or "flying saws" (synchronization of the driven shaft with the running spindle) can be freely connected on a common hardware and software platform. The hardware and software platform also supports a variety of parallel and series of motion graphics: 2D parallel motion graphics, 3D-Delta, cut motion graphics, Scara, coordinate gantry cranes, and rotating motion graphics.

The programming uses the rules of the coordinate system, where the inversion animations of the various relevant motor positions are calculated, and the selection and animation configuration are generated in the Twincat system. In animated channels, e.g. in Delta, pole length and offset are displayed in a digitized manner. For dynamic pre-control, the weight of the welded workpiece and the inertia of the weight can be given in advance. In order for the robot to smoothly pick up and lower the welded workpiece, the user can use the "flying saw" and "curve runner" functions to synchronize the implementation on the conveyor belt. For AX 5000 series Beckhoff drives, the Twincat motion picture converter is optimized (Figure 8).

Here SPS, motion control, HMI and robotics can only be run on industrial PC-CPUs. This has the following advantages for users:

●There is no need to set up a CPU to control the robot;

●Reduced energy costs because configuration, digitization and diagnostics are carried out in one system;

Twincat is a well-known, all-in-one tool for configuration, data and diagnostics;

●Through the mutual cooperation of various CPUs for SPS, motion control and robotics, the loss caused by mismatch is eliminated;

●The use of a direct interface eliminates the need for cumbersome interaction between CPUs, improving the efficiency and precision of welding work.

Automated tensioning of welded workpieces increases output by up to 30%

As mentioned earlier, welding operations can be monitored using Ethercat's track and trace inspection function on the basis of all data from the ARC-11 RB. In addition, because all the code comes from the same center, it is possible to parameterize user-specific code. By using Ethercat, user-specific code can be written relatively simply. Because most of the commissions received by ARC are special workpiece welding, the welding robot design commissions accepted by the company are often more troublesome and complex.

If we consider the complexity of the control design of the ARC-11-RB welding robot, the ARC-11-RB welding robot took only 4 weeks from design to application, and the subsequent structure and assembly were completed within 3 weeks. In this case, ARC has been able to automate the tensioning and removal of welded workpieces, increasing production by 30% compared to manual tensioning and removal of welds. In this case, only the loading and unloading of the welded workpieces is carried out manually. Thanks to Twincat, it takes only 1 hour to route the shafts of the robot control unit based on a simple topology. The welding robot has few control components and a compact mechanism, so the distribution box has a small external dimension.

Remote control is available from a PC control unit with Windows software

The PC control unit of the welding robot provided by ARC uses Windows software, so it is possible to provide users with remote control. Users can connect to their LAN to enable remote control of the welding robot, as well as access to ARC's online after-sales service. Welding robot users all over the world can get ARC support in problem analysis through remote control, in order to find the cause of problems caused by robot welding equipment, and eliminate these problems through changes in the software, which greatly reduces the cost of welding robot equipment maintenance for users.

ARC and Beckhoff have the potential to cooperate further with the Twincat 3 system: The cooperation between the two companies is advantageous in terms of the combination of integrated machine programming, visualization technology, and HMI visualization to form a single necessary software environment. ARC said that in view of the results achieved so far in improving the productivity of welding operations and reducing production costs, ARC will also use automation controls from Beckhoff of Germany on other machines and robots in the future.

FANU robots increase the economy of welding operations

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