Apparatus for cutting hollow pipe

In a machine for continuously producing spiral seamed hollow pipe from a metal strip including drive means for feeding the strip through the machine, means for forming the strip into a spiral cylinder so that the outer edges of the strip are adjacent each other, and means for joining the adjacent edges to produce a spiral seamed pipe, the pipe moving in an axial direction while it rotates, and the pipe having a front opening that moves away from the machine and a back opening in the forming means, the improvement comprising:

• a first passively rotatable cutting blade mounted in a front end of a boom, the boom and first blade fitting inside the pipe, a back end of the boom extending through the back opening of the pipe and the forming means, and the boom and first blade positioned inside the pipe so that the axis of the first blade is parallel to the pipe axis and the circumferential edge of the first blade is adjacent to the inner pipe surface;
• a second passively rotatable cutting blade mounted in a holding means, the holding means and second blade positioned outside of the forming means and the pipe so that the axis of the second blade is parallel to the axis of the pipe and the circumferential edge of the second blade is adjacent to the circumferential edge of the first blade in a lateral direction;
• means for moving the holding means towards the pipe so that the circumferential edges of the first and second cutting blades overlap and puncture the pipe;
• and
• guide means for allowing the pipe to pull the overlapping first and second cutting blades with the pipe as the pipe moves in an axial direction, so that the first and second blades cooperate to cut the pipe perpendicular to the pipe axis as the pipe moves axially and rotates between the overlapping edges of the first and second blades.

In a machine for continuously producing spiral seamed hollow pipe from a metal strip including drive means for feeding the strip through the machine, a looped-shaped means for forming the strip into a spiral cylinder so that the outer edges of the strip are adjacent each other, and means for joining the adjacent edges to produce a pipe having a spiral lockseam seam, the lockseam being at least twice as thick as the metal strip, the pipe moving in an axial direction while it rotates, and the pipe having a front opening that moves away from the forming means and a back opening in the forming means, the improvement comprising:

• a first circular, passively rotatable knife blade mounted in a front end of a boom, the boom and first blade fitting inside the pipe, a back end of the boom extending through the back opening of the pipe and the forming means, and the boom and first blade positioned inside the pipe so that the axis of the first blade is parallel to the pipe axis and the circumferential edge of the first blade is adjacent to the inner pipe surface;
• a second circular, passively rotatable knife blade mounted in a holding means, the holding means and second blade positioned outside of the forming means and the pipe so that the axis of the second blade is parallel to the axis of the pipe and the circumferential edge of the second blade is separated from the circumferential edge of the first blade by a fixed lateral distance;
• means for moving the second knife blade between a first position where the pipe can move freely past it and a second position where the circumferential edges of the first and second cutting blades overlap and puncture the pipe, wherein the moving means and holding means cooperate to maintain the fixed lateral separation between the first and second cutting blades;
• and
• guide means for allowing the pipe to pull the first and second knife blades in their second, overlapping position with the pipe as the pipe moves in an axial direction, so that the first and second blades cooperate to cut the pipe perpendicular to the pipe axis as the pipe moves axially and rotates between the overlapping edges of the first and second blades.

An apparatus for cutting pipe which is continuously formed from a metal strip, wherein the pipe has a spiral lockseam which is at least twice as thick as the metal strip, and the pipe moves axially and rotates while it is produced, comprising:

• only one inner rotatable cutting blade mounted for positioning inside the pipe and held in a fixed position relative to the inner pipe surface by a rigid boom, said inner blade adapted to be rotationally driven by contact with the moving pipe;
• only one outer rotatable cutting blade mounted for positioning outside of the pipe, and the outer blade being connected to the boom and separated from the inner blade by a fixed lateral distance, said outer blade adapted to be rotationally driven by contact with the moving pipe;
• means for moving the outer blade between a first position where the pipe can move freely past the outer blade and a second position where the outer and inner blades will overlap and puncture the pipe, and the moving means and boom cooperating to constantly maintain the fixed lateral separation between the inner and outer blades;
• and
• means for allowing the inner and outer cutting blades to be pulled by the pipe as it moves in an axial direction when the inner and outer blades are in their second, overlapping position so that the inner and outer blades will cooperate to cut the pipe when it moves axially and rotates between them in their overlapping second position.

For use with a machine for continuously producing spiral seamed pipe from a metal strip including drive means for feeding the strip through the machine, means for forming the strip into a spiral cylinder so that the outer edges of the strip are adjacent each other, and means for joining the adjacent edges to produce a spiral seamed pipe, the pipe moving axially while it rotates and having a front opening that moves away from the machine and a back opening in the forming means, an apparatus for cutting spiral seamed pipe comprising:

• a first passively rotatable knife blade mounted in a front end of a boom, the boom and first blade to be positioned through the forming means and inside the pipe so that the axis of the first blade will be parallel to the pipe axis and the circumferential edge of the first blade will be adjacent to the inner pipe surface;
• a second passively rotatable knife blade mounted in a holding means to be positioned outside of the forming means and pipe so that the axis of the second blade will be parallel to the axis of the pipe and the circumferential edge of the second blade is separated from the circumferential edge of the first blade by a fixed lateral distance;
• means for moving the holding means and second blade towards the first blade so that the circumferential edges of the first and second knife blades will overlap to puncture the pipe;
• and
• guide means for allowing the first and second knife blades to be pulled by the pipe as it moves in an axial direction when the first and second blades overlap, so that the first and second blades will cooperate to cut the pipe when the pipe moves axially and rotates between the overlapping edges of the first and second blades.

An apparatus for cutting continuously produced, spiral seamed pipe, where the pipe moves axially and rotates while it is produced, comprising:

• a first passively rotatable knife blade mounted in a front end of a boom and having a circumferential cutting edge, the rotational axis of the first blade being parallel to the boom axis;
• a second passively rotatable knife blade mounted in a holding means and having a circumferential cutting edge, the holding means positioning the second blade so that the rotational axis of the second blade is parallel to the rotational axis of the first blade, the cutting edge of the second blade is adjacent to the cutting edge of the first blade in a lateral direction, and, in a first position, the cutting edge of the second blade is displaced from the cutting edge of the first blade in a direction normal to the rotational axis of the second blade;
• means for moving the second blade in the direction normal to its rotational axis to a second position where the circumferential edges of the first and second knife blades overlap;
• and
• means for connecting a back end of the boom to the holding means so that the first and second blades will maintain a fixed lateral separation;
• and
• guides means for allowing the first and second knife blades to be pulled by the pipe as it moves in an axial direction when the first and second blades are in the overlapping, second position, so that the first and second blades will cooperate to cut the pipe when it moves axially and rotates between the overlapping edges of the first and second knife blades.