US 4,445,354 A · Procedure and equipment for the manufacture of pipes with external and internal diameters varying in stages

Abstract

The present invention relates to a cold pilger rolling mill and a method and means for manufacturing tubes with externally and/or internally thickened portions by reducing the tubes over a mandrel by means of grooved rolls which are mounted in a reciprocating roll stand. The invention provides several different varying diameter grooves on the rolls, which grooves can be brought into play one after the other by rotation of the rolls through an adjustment of the toothed racks on which the rolls are mounted. Consequently, at least one groove is provided for the rolling out of the required cross-section of most of the tube and a second groove is provided for the rolling of a thickened portion of the tube. It is essential that a smoothing zone is associated with each groove, and a zone for rotating and advancing the tube is associated with at least one of the grooves.

Claims13

Dependent claims

A cooperative pair of ring rolls for use in a cold pilger rolling mill for producing a tube having an external extending portion that varies in diameter, for example an enlarged end portion;

said rolls each having at least two different cooperative varying diameter tube producing grooves formed circumferentially around the periphery of said rolls, and
wherein said grooves are arranged in a common plane taken perpendicularly through the axis of rotation of said rolls, and
further wherein each of said grooves of a given diameter with reference to the processing sequence has after a deforming zone, a smoothing zone and as to at least one of said grooves an additional zone preceding the deforming zone for allowing movement of the tube relative to the roll.

A method for manufacturing a tube with varying external diameters by reducing a shell formed into a tube over a mandrel in a cold pilger rolling mill, which shell is worked between a set of driven ring rolls each having at least two different cooperative varying diameter tube producing grooves formed circumferentially around the periphery of said rolls, and each groove having a reducing range including a rotating and feeding zone, and a smoothing zone, the steps comprising:

(1) rolling a selected length of said shell in a first said groove to produce a desired first external diameter for said tube,
(2) rotating said rolls to bring a said second groove into operation for a continued working of said shell,
(3) rolling a selected length of said shell with said second groove to produce a second desired external diameter for said tube different than said first diameter,
said rolling in steps (1) and (3) being such as to subject said formed tube to said smoothing zones to effect final processing of said external diameters, and
(4) when said tube is in said first and second grooves rotating and selectively feeding said shell in said rotating and feeding zones.

2 more elements

Dependencies are inferred from the claim text.

Procedure and equipment for the manufacture of pipes with external and internal diameters varying in stages

Life of this patent

Procedure and equipment for the manufacture of pipes with external and internal diameters varying in stages

Life of this patent

Abstract

Claims13