By William G. Beazley, PhD
Robotic workstations are finding multiple applications in pipe and vessel fabrication, say exhibitors and speakers at HOUSTEX 2017. “Many subtractive technologies such as oxy fuel cutting, plasma gouging and drilling and tapping and polishing benefit from the 3 dimensional capability of robotics,” said Dan Allford, President of ARC Specialties in Houston. Additive technologies, such as weld surfaces and thermal sprays are used for cladding, repairs and wear protection. The 3D versatility and programmability of robots with the expanding choices of end effector tooling makes it an ideal choice for the one-off custom fabrication industry.
Numerically Controlled (NC) flame cutting and welding has been used in the fabrication industry for decades. For example, the common NC oxy fuel flame cutter for plate uses 2 dimensional control for positioning the torch plus possible controls on the torch depth, a 3rd dimension. This is a 3D or 3 axis subtractive machine.
Pipe and vessels generally have cylindrical, spherical, ellipsoid or complex curved surfaces. Usually a hole is cut for welding, so beveling is needed for proper welding of branch pipes and nozzle necks. So, more dimensions are needed, up to 6 (3 positions, 3 orientations) plus tooling control(s). The 6+ dimensional coordinates vary along the path of the cut.
Pipe cutting is often done with one machine controlling the pipe and a second machine controlling the position of the cutter. (See example from Industrial Solutions and Innovation, LLC., of Alvin, TX.) Both machines can be coordinated to perform complex actions.
For complex contours, like vessel heads, flexibility, programmability and other issues make robotic “arms” or manipulators the best choice. Most robotic arms have strong and stiff servos in their “joints” to allow the tool to be positioned and oriented as needed for beveled holes to be cut along a path to the correct depth.
Allford says there are six main considerations in selecting robots for material removal:
1. Equipment cost
2. Work envelope
3. Number of axes and positioning flexibility
4. Travel speed
5. Tooling
6. Tolerance to harsh environments
Allford says many applications are either plasma or oxy fuel cutting. Oxy fuel uses the oxidation of the metal to generate the heat needed to melt needed for the cut. Plasma cutting supplies its own energy but doesn’t need to “start” the cut’s combustion and makes a more precise cut. He illustrated the various types of applications from its long history with pipe and vessel fabricators.
A developing area is additive applications. Weld cladding has been used on vessels and pipe for many years. Thermal sprays which add material by injecting powder into a flame or striking it with a laser is another technique which can add material to repair or add abrasion resistance.
Although robot machines are more expensive to purchase, their flexibility and programmability leads to lower fabrication costs and better precision. Jason Hays of Top Coat in Jones Creek, TX, reports, “we get a fabrication savings of up to 50% from 75% increased productivity.”
View Arc Specialties’ playlist at
https://www.youtube.com/playlist?list=PLJiFG5e84Mbz-3cgtZ2opEdmTXRzr1b_8
For more information, contact:
Dan Allford, Arc Specialties, 1730 Stebbins Dr., Houston, Texas 77043, 713 631-7575, www.arcspecialties.com
Jake Smith, Industrial Solutions and Innovation, LLC., 4420 Mustang Road, Alvin, TX 77511 (281) 824-0356, https://www.industrialsolutions-llc.com/
Jason, Hayes, Top Coat, Inc., 9720 Hwy 36 | Jones Creek, TX 77541, 979-233-9558, http://www.topcoatinc.com/