Beveled cutter
Disclosed is a method, apparatus, and design of a fusion welded pipe wherein the effects of an inner bead of the fusion weld are minimized. The internal shape of the pipe prior to welding may be configured in several different shapes so that the beads or lips produced by the fusion welding process are unobtrusive and do not interfere with the function of the pipe. In a likewise manner, the outer shape of the pipe prior to welding may be configured so that the lips are unobtrusive on the external surface of the pipe.
1. A method for joining a first plastic pipe to a second plastic pipe with at least a partially recessed internal bead comprising:
placing said first plastic pipe in a holder;
cutting said first plastic pipe substantially perpendicular to the axis of said first pipe with a profile that reduces the wall thickness of said first pipe with an undercut region on the internal side of said first pipe;
cutting said second plastic pipe substantially perpendicular to the axis of said second pipe with a profile that reduces the wall thickness of said second pipe with an undercut region on the internal side of said second pipe;
heating the ends of said first pipe and second pipe substantially simultaneously; and
forcing said first pipe and second pipe together to form a weld, said weld having a bead that is substantially recessed within only a portion of said undercut region of said first pipe and within only a portion of said undercut region of said second pipe.
2. The method of claim 1 wherein said undercut region of said first pipe comprises a substantially cylindrical surface parallel to said axis of said first pipe with a length along said axis at least as great as the difference between the radius of said cylindrical surface and the inner diameter of said first pipe.
3. The method of claim 1 wherein said undercut region of said first pipe comprises an internal bevel that reduces said wall thickness by at least about the size of said bead.
4. A machine for butt welding a first plastic pipe to a second plastic pipe with at least a partially recessed internal bead comprising:
a holder for receiving said first plastic pipe;
a cutter adapted to cutting said first plastic pipe substantially perpendicular to the axis of said first pipe with a profile that reduces the wall thickness of said first pipe with an undercut region on the internal side of said first pipe, said cutter comprising a plurality of cutting blades to machine the perpendicular surface of the pipe, and a plurality of cutting blades to machine the said profile;
a holder for receiving said second plastic pipe;
a cutter adapted to cutting said second plastic pipe substantially perpendicular to the axis of said second pipe with a profile that reduces the wall thickness of said second pipe with an undercut region on the internal side of said second pipe, said cutter comprising a plurality of cutting blades to machine the perpendicular surface of the pipe, and a plurality of cutting blades to machine the said profile;
a heater for heating the ends of said first pipe and second pipe substantially simultaneously; and
a clamping mechanism for forcing said first pipe and second pipe together to form a weld, said weld having a bead that is substantially recessed within said undercut region of said first pipe and said undercut region of said second pipe.
5. The machine of claim 4 wherein said cutter of the first pipe is adapted to form said undercut region of said first pipe to comprises a substantially cylindrical surface parallel to said axis of said first pipe with a length along said axis at least as great as the difference between the radius of said cylindrical surface and the inner diameter of said first pipe.
6. The machine of claim 4 wherein said cutter of the first pipe is adapted to form said undercut region of said first pipe to comprises an internal bevel that reduces said wall thickness by at least about the size of said bead.
7. A machine for butt welding a first plastic pipe to a second plastic pipe with at least a partially recessed external bead comprising:
a holder for receiving said first plastic pipe;
a cutter adapted to cutting said first plastic pipe substantially perpendicular to the axis of said first pipe with a profile that reduces the wall thickness of said first pipe with an undercut region on the external side of said first pipe, said cutter comprising a plurality of cutting blades to machine the perpendicular surface of the pipe, and a plurality of cutting blades to machine the said profile;
a holder for receiving said second plastic pipe;
a cutter adapted to cutting said second plastic pipe substantially perpendicular to the axis of said second pipe with a profile that reduces the wall thickness of said second pipe with an undercut region on the external side of said second pipe, said cutter comprising a plurality of cutting blades to machine the perpendicular surface of the pipe, and a plurality of cutting blades to machine the said profile;
a heater for heating the ends of said first pipe and second pipe substantially simultaneously; and
a clamping mechanism for forcing said first pipe and second pipe together to form a weld, said weld having a bead that is substantially recessed within said undercut region of said first pipe and said undercut region of said second pipe.
8. The machine of claim 7 wherein said cutter of the first pipe is adapted to form said undercut region of said first pipe to comprises a substantially cylindrical surface parallel to said axis of said first pipe with a length along said axis at least as great as the difference between the radius of said cylindrical surface and the outer diameter of said first pipe.
9. The machine of claim 7 wherein said cutter of the first pipe is adapted to form said undercut region of said first pipe to comprises an external bevel that reduces said wall thickness by at least about the size of said bead.