Refined Solution
By Design Engineering Staff
Motion Control Power Transmission ball screwBall screw assemblies key to patent-pending petroleum corrosion technology.
The dual-torch oscillation process involves feeding CRA wire into a 20′ long torch that welds it circumferentially along the inner wall of the steel pipe. The circumferential weld is created by Nook’s ball screws wiggling the torch into the pipe back and forth approximately 1" per second, while motorized pipe rollers steadily turn the pipe. The first 20 feet of pipe is coated, then flipped 180 degrees. The torch is then put back to coat the other half of the pipes’ inside diameter.
Each oscillation places a heavy load on the ball screw with the 20′ torch decelerated, stopped and reversed 120 times a minute with loads running just under 1,000 lbs. during acceleration. The accelerate/decelerate rate is a harsh and rapid speed/load oscillation of .8" at around 1 hertz (Hz) per second. The oscillation process also moves the weld puddle side-by-side, which generates approximately two times the weld yield. Additionally, this single-pass circumferential weld ensures that the CRA overlay is seamless and also allows the pipe to undergo long-radius bending after the overlay process.
“The oscillation process is a harsh application since it runs and repeats without stopping for hours at time,” says Dan Allford, president of ARC Specialties. “Therefore, the reliability and performance of Nook’s ball screws is vital and a key basis for our patent-pending process.”
Nook provided ARC with its Precision-Rolled Ball Screws and ARC customized them to meet their unique application specifications. Nook offers its ball screw assemblies in a wide range of materials including alloy, stainless steel, titanium and other exotic metals. Nook’s ball screws are available to meet a customer’s application performance requirements (e.g. stainless steel for medical, non-magnetic, non-corrosive applications).
