Tech Front: ROVs Travel Deep in Subsea Energy Search
Remotely operated vehicles (ROV) rose to the top of public consciousness with the Gulf oil spill disaster in April 2010. Streaming video from ROVs working to staunch the flow of oil from the Macondo well was seen on television screens around the world in real time after the Deepwater Horizon rig exploded, burned and sank. Before the oil surge was stopped, an estimated 5 million barrels of oil would be released before the well was brought under control three months later through ROV technology.
Development of deepwater oil and gas fields at depths to 13,000+ ft (4000 m) has challenged the complexity and reliability of ROV technology required to meet all the requirements of exploration, drilling, completion, and intervention. "In addition to trouble-shooting in the Gulf, ROVs are needed for every aspect of subsea oil and gas exploration and production," said Tyler Schilling, regional manager, FMC Schilling Robotics (Davis, CAia). "ROVs map the sea floor, work in drilling and completion, construction and installation of trees, manifolds, and plumbing, perform workovers to restore the productivity of wells, and finally facilitate abandonment by cementing wells, removing equipment, and cutting off tubing below the sea floor." Most of the robotic manipulator arms and two of the ROVs used in the Gulf intervention were manufactured by FMC Schilling Robotics.
Principal components of a ROV system are the submarine with two installed manipulators and a tether management system (TMS). The ROV is lowered into position under a TMS (Top Hat) and then released attached to the TMS by a tether which carries electric power, video and data signals necessary for monitoring and control. ROVs are equipped with a combination of video cameras, searchlights and sensors required for the tasks at hand. Launch and recovery systems and control vans are also needed.
Assembly of the ROV systems is done at FMC Schilling’s headquarters and assembly facility in Davis. Machining of components is performed in a separate machine shop using horizontal machining centers, the NH 5000 and the NH 6500, from DMG Mori Seiki USA (Hoffman Estates, IL). Components machined to exacting dimensions and accuracies include actuators, joints, robot arms and fluid sealing system components that are essential to keep sea water out and oil and fluids in the ROV systems.
"Our modular approach to system design encompasses mechanical, electrical, electronic and hydraulic sub-systems. But computer-crash-like events are a way of deep-ocean life in our business," said Schilling, emphasizing the importance of reliability and design. While FMC Schilling Robotics has designed its ROV systems to be robust in the deepest water, every design effort has been made to keep maintenance simple and accessible through comprehensive system diagnostics and intuitive maintenance solutions.
FMC Schilling offers two ROV models, the UltraHeavy-Duty (UHD) and the Heavy-Duty (HD) remotely operated ROV systems. The HD is equipped with 150 hp (112-kW) motor for propulsion and hydraulic pump actuation with depth rating of 3000 m (4000 m optional) and 425-m tether length for medium-duty capabilities in the construction area. The UHD ROV features 200 hp (149-kW) motor, is rated to 4000 m, and has an 850-m tether and is designed for heavy-duty applications and construction requirements.
ROV pilots, sitting at dual consoles on the surface, perform complex operations while the ROV automatically compensates for challenges of the deep sea environment, like high currents and low visibility. The working tools (arms) of the ROV are the manipulator systems. Manipulators perform a variety of intervention tasks. The manipulator systems comprise an arm on the right side that features dexterity and an arm on the left side that is designed for powerful and heavy duty operations.
The Titan 4 manipulator, for example, is primarily titanium with a maximum reach of 1922 mm and lift of 122 kg at full reach, and is depth rated to 4000 m with an optional depth rating of 7000 m. These systems range from the five-function RigMaster to the seven-function position controlled Titan 4. The RigMaster is anodized aluminum, stainless steel, and titanium. Other manipulators available from FMC Schilling include the Conan, Orion, and Atlas manipulator systems that are made from anodized aluminum and stainless steel.
FMC Schilling Robotics is a global supplier to the seabed-to-surface engineering, construction and energy services industry with more than 2000 manipulator systems operating on virtually every work-class ROV in the world. In 2012, over 250 robot arms and 20 robot submarines were shipped. And in 2012, FMC Technologies completed acquisition of Schilling Robotics by purchasing the remaining 55% interest it didn’t already own. MEFor more information from DMG Mori Seiki, go to
www.dmgmoriseikiusa.com, or phone 847-593-5400
For more information from DMG Mori Seiki, go towww.dmgmoriseikiusa.com, or phone 847-593-5400
Aero Engine Holes
Drilled Fast with EDM
Requirements for fast precise drilling of cooling air holes and shaped diffuser holes in blade and vane segments for aerospace applications have grown substantially due to new engine programs that emphasize improved engine performance and reduced fuel consumption. Always a challenge, producing the wide range of hole shapes and sizes within a single setup is highly desirable to reduce the variety and number of tools required, as well as overall cycle times.
The new EDBV3 Fast Hole Drill EDM from Makino (Auburn Hills, MI) builds on Makino’s proven EDM platforms with onboard filtration and resin systems and a user-friendly control system featuring preprogrammed hole profiles. The two-axis rotary table in combination with automatic tool change (ATC) and automatic guide change (AGC) systems enables manufacturers to machine complex features untended, saving time and money without the risk of losing part quality or accuracy.
All EDM drilling with the EDBV3 is performed fully submerged under water for higher part quality, improved stability, and up to ten times faster processing speeds than conventional technologies. To further improve productivity, the EDBV3 uses a single-electrode processing approach, which avoids the high cost of custom multi-electrode holders and standardizes the tool holders with a flexible and cost-efficient system.
To prevent back-wall impingement during blade and vane cavity wall penetration, the EDBV3 includes a proprietary sensitive breakthrough detection circuit. This sensing capability uses a combination of different adaptive process-monitoring techniques. The machine’s fully submerged processing delivers additional support by allowing debris flushing during breakthrough for a faster and more stable process.
The EDBV3 features XYZ-axis travels of 370 x 270 x 500 mm with a 250 x 270-mm worktable able to handle a maximum workpiece load of 5 kg with an optional 15 kg payload available. The rotary C-axis head features an EROWA compact chuck that enables automatic changing of electrodes down to 0.2-mm diameter and is able to spin up to 1000 rpm. For untended burning of varying cooling hole diameters, the ATC and AGC systems combined into a common assembly provide simple and precise automated exchanges in 30 seconds.
The EDBV3 uses a rigid guide-arm assembly to hold, locate and support the die guide, which can be alternately used as a programmable W-axis. An integrated middle-guide system can be applied for small diameter electrodes preventing whipping, bending and vibration. The middle-guide fingers automatically retract as the electrode tube reduces in size, using as much of the electrode length as possible. The standard configuration of the EDBV3 includes a 24-station tool carousel system and 24 holder assemblies to fully tool up the machine. The tool carousel can be exchanged as a palletized magazine for extended hours of automated operation.
Software technologies used in Makino’s fine-hole sinker EDM machine and the Model Plan system are integrated into the controller, providing input screens with direct G and M-code programming formats. An electrode length management system provides electrode wear tracking and automatically exchanges electrodes when lengths become too short. ME
For more information from Makino, go to www.makino.com, or phone 800-552-3288.
Turbo Milling Fir Tree Profiles
Fir tree profile machining for turbo machinery is benefiting from a technique that uses trochoidal machining strategies in Delcam’s PowerMILL software for five-axis machining. The milling approach has been patented by Iruba, a German provider of engineered solutions. The technique was recently demonstrated in an event hosted by INIRAM Precision, a Peabody, MA importer and distributor of five-axis milling machines. The milling approach allows complex fir-tree profiles to be produced on five-axis milling machines, rather than having to use specialist broaching equipment. Milling was demonstrated on Hermle C60 five-axis machining center for a complex fan disk.
The use of trochoidal strategies provides a number of benefits, for example, giving high materials removal rates with lower and more consistent cutting forces. The more consistent cutting forces also ensure higher accuracy in the position and in the shape of the slots with minimal thermal effects on the surface of the profile. The process also reduces the number of specialist cutting tools that are required and cuts the machining time in steel alloys by 30 to 40%, compared with alternative standard milling solutions. Cutting time is almost equal to that of broaching.
Introduced at IMTS, the technique was demonstrated milling small IN718 fir-tree geometries, a typical material for aero engine parts. Machining was done on Hermle’s smallest five-axis machine, the C22. The process is capable of milling curved slots, deburring, and measuring them in one process. At the INIRAM event, the process was demonstrated using CO2 coolant to provide a "green" element to production of fir tree milling and blisk and blade machining. ME
For more information on Delcam, go to www.delcam.com, or phone 828-299-9924; for more information on INIRAM Precision, go to www.iniram.com, or phone 978-854-3037.
This article was first published in the February 2013 edition of Manufacturing Engineering magazine. Click here for PDF.