Method of making a tubular member by helically coiling a metallic strip, tubular member produced by this method and device for carrying out this method

Claim 2

Method of manufacturing a flexible tubular member by coiling a metallic strip having longitudinally extending abutment means into a helix having overlapping turns, which method comprises the steps of imparting an arcuate deformation to said strip such that the edge of said strip which is to be on the outside of the overlapping turns in the completed tubular member is longer than the edge of the strip which is to be on the inside thereof, coiling said strip into a helix in which, when said helix is a axially unstressed, the turn last formed lies on one side of the preceding turn, and stressing said strip by positioning the lastformed turn on the other side of said preceding turn, with the portion of the of the longitudinal abutment means in each turn contacting a surface on an adjacent turn to resist a return of said strip to its unstressed position.

Claim 3

Method as claimed in claim 1 in which, when said helix is axially unstressed, the shorter edge of the section of said strip defining said last-formed turn lies close to the longer edge of the section of said strip defining the preceding turn, and the longer edge of the strip defining said last-formed turn is adjacent the shorter edge of the section of said strip defining said preceding turn when said helix is axially stressed.

Claim 4

Method as claimed in claim 1 in which the edges of said strip are hooked in opposite directions and the adjacent edges of adjacent turns are hooked over each other to resist separation of said turns axially of said tubular member.

Claim 5

Method as claimed in claim 1 according to which said strip is made of strong steel.

Claim 6

Method as claimed in claim 1 according to which the tubular member is formed about a plastic tube.

Claim 7

Flexible tubular member in the form of a helical coil having overlapping turns made from an arcuate metal strip, one edge of which is longer than the other, said strip comprising longitudinally extending abutment means, and being under an internal tension biassing the shorter edge of each turn of said coil toward the adjacent longer edge of an adjacent turn until the abutment means of each turn engages a cooperating surface on an adjacent turn with a force sufficient to cause said turns to reverse their relative positions axially of said coil if said reversal were not prevented by said engagement.

Claim 8

Flexible tubular member in the form of a helical coil having overlapping turns made from an arcuate metal strip, one edge of which is longer than the other, said strip comprising longitudinally extending abutment means, and being under an internal tension biassing the shorter edge of each turn of said coil toward the adjacent longer edge of an adjacent turn until the abutment means of each turn engages a cooperating surface on an adjacent turn with a force sufficient to cause said turns to reverse their relative positions axially of said coil if said reversal were not prevented by said engagement.

Claim 9

A tubular member as claimed in claim 6 encircling a fluid-tight tube and adapted for use in drilling oil wells.

Claim 10

Device for forming a flexible tubular member from a metallic strip of material having longitudinally extending abutment means which comprises in combination, means for leading the strip along a plane substantially parallel to the axis of the tubular member which is to be formed, means for imparting a permanent arcuate deformation to said strip such that the edge of the strip in the direction in which the tubular member is being formed is longer than the other edge of the strip, means for imparting a helical deformation to said strip to form it into a helix having a diameter substantially equal to that of the member being formed, and for engaging the longer edge of the turn being formed with the turn which has just been formed, means for guiding the tubular member thus formed, and means for synchronizing the speed of rotation of the tubular member being formed and the feed of the strip from which the member is to be formed.

Claim 11

Device for forming a flexible tubular member from a metallic strip of material having longitudinally extending abutment means which comprises in combination, means for leading the strip along a plane substantially parallel to the axis of the tubular member which is to be formed, means for imparting a permanent arcuate deformation to said strip such that the edge of the strip in the direction in which the tubular member is being formed is longer than the other edge of the strip, means for imparting a helical deformation to said strip to form it into a helix having a diameter substantially equal to that of the member being formed, and for engaging the longer edge of the turn being formed with the turn which has just been formed, means for guiding the tubular member thus formed, and means for synchronizing the speed of rotation of the tubular member being formed and the feed of the strip from which the member is to be formed.

Claim 12

Device as claimed in claim 8 in which the means for imparting an arcuate deformation to the strip comprises a set of rollers which bends said strip beyond its elastic limit.

Claim 13

Device as claimed in claim 8 in which the means for forming the strip into a helix comprises a forming head including a plate mounted on a universal joint so that its position m be adjusted about both a horizontal and a vertical axis.

Claim 14

Device as claimed in claim 10 in which the plate comprises a central orifice through which the tubular member is being formed and that the forming fingers are positioned on the periphery of this orifice by supports which are angularly and longitudinally adjustable.

Claim 15

Flexible tubular member as claimed in claim 6 in which the edges of said strip are hooked in opposite directions and the adjacent edges of adjacent turns are hooked over each other to resist separation of said turns axially of said tubular member.

Claim 16

Device as claimed in claim 8 in which said means for imparting an arcuate deformation to said strip imparts said arcuate deformation in a plane passing through both edges of the strip.