NEXT STEPS IN ROBOTIC WELDING
These best-in-class robots and control systems serve the welding and metal fabrication markets that are currently the primary growth areas for robotics.
Posted: May 8, 2011
The sensor was developed by Meta in collaboration with CRC-Evans Pipeline International, Inc. (Houston, TX), a world leader in pipeline welding and the launch customer for the sensor, with worldwide exclusivity for its use in pipelines. The version of the SLS for pipeline welding and inspection is called “CiRCvision“. Meta services demand for the sensor in all markets other than pipeline.
Background To SLS Development
Off-the-shelf laser systems are capable of high-speed joint tracking, but have limitations regarding unit cost, robustness, ease of use and suitability for typical pipeline construction field conditions. These limitations made previous generation systems unsuitable for general use with the large CRC-Evans welder fleet.
The company’s brief to Meta was to create a low-cost, self contained, intelligent, smart vision system with digital communication capabilities to be used in enhancing weld joining applications at 3 m/min or better and also for inspection of pipelines. CRC-Evans identified that the overall pipe joining process could be dramatically improved if additional information about weld preparations and welds could be obtained before, during and after welding.
The result is the Meta SLS, which consists of a robust CMOS megapixel image sensor with very large scale integration devices, including a large FPGA (field-programmable gate array) and a powerful DSP (digital signal processor) inside the sensor head itself.
Weld Joint Tracking
The nature of narrow gap welding in pipelines makes it impossible to have precise alignment all around a given weld joint due to irregularities in joint fit-up as a result of variations in pipe diameter and ovality. This leads to local changes in joint geometry and position.
The SLS measures these changes in real time during welding. Tracking data is sent via a high-speed Ethernet or CANbus interface to the motion control system driving the external welding system. The resulting closed loop control ensures reliable, noise-free data transmission, ensuring that the welding electrodes are always where they should be.
The tracking algorithms vary with the type of weld pass. For example, during root welds, the laser vision system provides accurate tracking without the need to oscillate that is a requirement of through-arc tracking. This results in more accurate bead placement and better weld penetration. Experiments have shown that the high resolution of the SLS makes it possible to use laser tracking for all stages of the welding process, including capping.
Adaptive Welding
Since the laser sensor works in 3D, effectively taking slices through the weld joint, it is able to compute accurately the weld volume in real time, allowing adaptive control over key welding parameters. The combination of accurate seam tracking appropriate for the pass being welded, together with adaptive fill based on actual measured joint volumes, makes it possible to achieve consistent, high quality welds at higher speeds than would otherwise be possible.
Bevel and Root Bead Inspection
One of the keys to efficient pipeline welding is for the line crew to be able to bevel pipe ends consistently, accurately and quickly despite variations in pipe end diameter and ovality. As the SLS is basically an instrument for measuring 3D profiles, it can also be used to inspect bevel geometry. This identifies any problems while the bevelling machine is still in position, enabling rapid rectification. All features such as root face (land) thickness, bevel angle, offset and root angle can be measured and compared against a desired template.
Using SLS, the root weld – the most critical phase of pipe joining – may be similarly inspected after it has been laid. If a faulty root bead is welded over and the defect not discovered until later, the cost of repair becomes high, so potential savings are large. Inspecting the shape of the root weld also gives an additional method of inspecting critical fatigue applications, such as risers, by measuring weld shape parameters such as mismatch and bead concavity. www.meta-mvs.com
IMPROVED INDUSTRIAL ROBOT PROGRAMMING, CONTROL
ABB Robotics (Auburn Hills, MI) offers the latest version of its robot controller software, RobotWare 5.13, that provides manufacturers with improved programming and control of robotic equipment, and enhanced functionality, safety and motion control. For manufacturers this will facilitate smarter, leaner robot cell concepts and superior control of production lines.
A leaner, less-restrictive safety system is a major advancement provided by RobotWare 5.13 through powerful new features added to SafeMove, a market leading robot safety system. Using these features, even more precise control of robot motion can be achieved, allowing integrators to more efficiently optimize robotic cell design and production flow. RobotWare 5.13 software is also 100 percent compatible with the new IRC5 Compact controller which combines the powerful performance of the standard IRC5 controller, including superior motion control and flexible RAPID language, with a significantly reduced footprint.
“What should interest many robot users is the Compact version of the IRC5 controller for a wide range of robot types,” noted Joe Campbell, vice president sales and marketing for ABB Robotics, North America. “In addition to the small IRB 120 robot, RobotWare 5.13 allows the IRC5 Compact controller to be used with the IRB 140 and IRB 1410 robots. And this range is expanding.”
One feature integrated into RobotWare 5.13 is Torque Slave software that enables multiple motors to be driven as a single logical axis. Using this function the robot is able to control heavy-duty equipment, such as large workpiece positioners. To extend the savings associated with the low-cost DeviceNet™ Lean bus to more end-users, ABB has extended it to support up to 20 units (previously 6) and to allow the control of third party I/O units. In addition, the lean version of DeviceNet protocol offers new auto configuration and bus scan tools for seamless communications with all connected devices. www.abb.com/robotics
REVERSED LOWER ARM EXPANDS WORK ENVELOPE
Slim and fast, the 6-axis MA1650T “Master Arc” welding robot from Motoman (Dayton, OH) features a “reversed” lower arm that provides a greater working range and depth of envelope. Available in ceiling- or wall-mounted configurations, the MA1650T offers a greatly expanded working range when combined with MotoSweep™ radial gantry. The unique arm configuration avoids the reach limitations of a standard robot when inverted.
The space-saving MA1650T robot increases productivity through its cutting-edge Sigma-5 motor control technology. It features a 10 kg (22.1 lb) payload, 1,653 mm (65.1 in) horizontal reach, 2,935 mm (115.6 in) vertical reach and ±0.08 mm (±0.003 in) repeatability. Its integrated through-the-arm torch cabling eliminates cable interference, simplifies programming and reduces cable wear. Feeder cable and welding utilities (gas and air hoses) can be routed through the robot base.
The MA1650T robot uses the dynamic, next-generation DX100 controller that features patented multiple robot control technology to easily handle multiple tasks and control up to eight robots (72 axes), I/O devices, and communication protocols. Featuring a robust PC architecture with unmatched memory capacity, the DX100 uses a Windows® CE programming pendant with color touch screen. Menu-driven arc welding software is provided. Digital welding interfaces are supported for Miller Auto-Axcess™ and other brands of power sources. The energy-saving DX100 controller features faster processing speeds for smoother interpolation, advanced robot arm motion, built-in collision avoidance, quicker I/O response and accelerated Ethernet communication. It is compliant to ANSI/RIA 15.06-1999 and other relevant ISO and CSA safety standards. www.motoman.com
INTEGRATED UPPER ARM TORCH
Fast and highly flexible, the 6-axis MA1400 “Master Arc” welding robot from from Motoman (Dayton, OH) significantly increases uptime by integrating the torch into the upper arm. Available in floor-, wall- or ceiling mounted configurations and ideal for high-density layouts, the space-saving MA1400 robot increases productivity due to its cutting-edge SIGMA V motor control technology.
The MA1400 robot has a 3 kg (6.6 lb) payload, 1,434 mm (56.5 in) horizontal reach, 2,511 mm (98.9 in) vertical reach and ±0.08 mm (±0.003 in) repeatability. Its integrated through-the-arm torch cabling eliminates cable interference, simplifies programming and reduces cable wear. Power cable and welding utilities (gas and air hoses) can be routed through the robot base. The MA1400 is perfectly suited for use in high-density workcells with multiple robots working in close proximity, as well as for applications that require access to parts in tight spots or those with potential interference from fixtures.
The MA1400 robot uses the dynamic, next-generation DX100 controller that features patented multiple robot control technology to easily handle multiple tasks and control up to eight robots (72 axes), I/O devices, and communication protocols. Featuring a robust PC architecture with unmatched memory capacity, the DX100 uses a Windows® CE programming pendant with color touch screen. www.motoman.com
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