In 2008, the George A. Mitchell Company delivered Two (2) 500 TON Drill Pipe and Casing Tube End Forming Machines to VAM USA of Houston, Texas.
The 1,000,000 Lb. End Forming Machines are the largest of their type ever produced by Mitchell. The process is very similar to Push Pointing, however, the API Drill Pipe and Casing material possesses yield strengths up to 150,000 PSI.
The End Forming Machines prepare, via cold forming, the ends of seamless Drill Pipe andCasing Tubes prior to machining a Premium Thread, of which VAM USA is a world leader. The tube diameters accommodated range from 4-1/2” up to 10-3/4”. The machines perform one of two operations, a mandrel expansion, required prior to machining a female premium thread and a die reduction, required prior to machining a male premium thread. These machines will be installed in a totally new VAM USA facility in the Houston area, in a continuous line process, which allows VAM to provide quick deliveries of the highest quality premium threads.
MITCHELL PUSH POINTERS are hydraulically powered. Contoured gripper jaws hold the tube in place while drawing dies are successively forced over the end of the material reducing itto a smaller diameter. A special MITCHELL device guides the reduced end producing a straight and concentric point. This perfectly round point has a uniformly gradual reduction from the tube O.D. The resulting high tensile strength all but eliminates the loss of the point at the start of subsequent drawing operations. Wall thickness of the point is generally greater than that of the tube, but the point can never be closed solid. A center hole always remains in the point to permit free air passage during later processing. MITCHELL PUSH POINTERS are used in both the ferrous and nonferrous industries to accommodate pierced, extruded, tube reduced, welded, and previously drawn tubes. All pointing operations are done cold. Using jaws with a gripping surface specially developed for the purpose, ferrous tubes can be pointed in the prelubricated condition. This is a major MITCHELL advantage - eliminating pickling and lubing after preheating that is usually required [especially for thick wall tubes] when other pointing methods are used.
A wide variety of tube Push Pointer designs is offered, with pushing capacities ranging from 5,000 Ibs. (22kN) to 1,000,000 Ibs. (4,450kN), to accommodate tube sizes from 0.25" (6.4mm) to 16" (406mm) O.D. and walls ranging from .010" (0.25mm) to 1.500" (38mm). The Units are provided with either a linear or rotary indexing mechanism or an "In Line" design to present two to six dies in succession to suit the requirements. Machine cycle times are extremely fast, varying from 3 to 35 seconds, depending upon the size of Pointer and type of operation.