Westinghouse Electric Corporation

Charles S Cook

George P Sabol

John P Foster

Edward S Diaz

A production measuring system is provided for early identification of dimensional or operational problems in a pilger forming device. The forming device has a mandrel for supporting a tubular workpiece to be elongated and thinned, at least two opposed dies bearing against the workpiece, and a mechanical drive for rolling the dies over the workpiece under pressure while periodically rotating and advancing the workpiece along the mandrel. Sensors are directed at the workpiece and produce signals reflecting displacement of the workpiece in rotation, axial displacement and transverse displacement. The signals can be compared to nominal standards and/or graphed and displayed, for visualizing operational conditions. The sensors can be disposed axially before or after the dies, or both. Preferably, idler rollers coupled to rotary variable differential transformers encode axial and rotational displacement after the dies (on the formed workpiece), and a pair of non-contacting proximity sensors disposed at right angles encode transverse displacement of the workpiece before the dies.

Monitoring pilger forming operation by sensing periodic lateral

A method of producing enhanced radial texture in zirconium alloy tubing suitable for use in forming cladding for nuclear fuel rods is provided. The tubing production method described herein employs a combination of mechanical expansion and heat treatment steps in the final stage of tubing formation to produce a single peak radial texture in the tubing, thereby imparting enhanced resistance to pellet-cladding-interaction to the finished tubing. The tubing is preferably processed to a diameter within less than about 10 to 20% of the desired final diameter, annealed, and expanded less than about 10 to 20% to the desired final diameter, thereby producing a unique radial texture in the finished tubing. In an alternative method, the finally expanded tubing is subjected to a final recrystallization anneal to produce a significantly enhanced split radial texture.

Single peak radial texture zircaloy tubing

A pilgering die for use in cold forming of tubular members is in the shape of a ring member having a groove in the outer periphery thereof and a bore therethrough, the die composed of at least two different alloy sections. The case or outer region of the die is formed from a first steel alloy which hardens by transforming to martensite under predetermined heat treating conditions while the core or inner region of the die is formed from a second steel alloy that does not transform to martensite under the heat treating conditions used to harden the case. A third alloy section of a material which hardens by martensite formation may be provided adjacent the bore through the die. Also, the second alloy section may be comprised of a steel alloy that has a higher thermal expansion rate than the thermal expansion rate of the first alloy section.

Pilger die for tubing production

A method of producing tubing composed of material, such as zirconium and alloys thereof, having a hexagonal close-packed crystal structure is provided which increases the radial texture or orientation of basal poles in the crystal structure of the material. The method includes intermediate and final stages. In the intermediate stage, multiple tubing reductions are performed, which each causes tubing wall thickness and diameter reduction and axial elongation, and a recrystallization anneal is performed following each of the tubing reductions. In the final stage, a last tubing reduction is performed, which causes tubing wall thickness and diameter reduction and axial elongation, and a final anneal is performed following the last tubing reduction. Also, in the intermediate stage, an expansion of the tubing diameter is performed following any one of the multiple tubing reductions and associated recrystallization anneals and then a recrystallization anneal is performed following the diameter expansion and before a next following tubing reduction in either of the intermediate and final stages of producing the tubing. The diameter expansion is an increase of from about five to twelve percent of the diameter of the tubing prior to the diameter expansion. The recrystallization anneal following the diameter expansion is at about 1250 degrees F. The tubing diameter expansion and recrystallization anneal result in enhanced texture of the finished tubing after completion of the final stage.

Texture enhancement of metallic tubing material having a hexagonal

Pilgering apparatus for reducing a tube particularly of zirconium alloy. The reduction is effected by grooved annular dies. Each die has a recess in its bore extending between the surfaces on which the die is mounted on the shaft on which it is rotated. Under the pressure applied to reduce the tube, the die is flexed. As a result of the flexing tension exists in the die in the volume near the recess and pressure is developed in the volume near the groove in which the tube is engaged. The pressure counteracts the tension resulting from the tube-reducing pressure. Each die is case hardened in the region of its grooves but not in the region of the recess.

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Murrysville Boro, PA, United States of America

Charles S Cook