Apparatus for bending plastic pipe

Details Apparatus for bending plastic pipe Apparatus for bending plastic pipe

1994-06-13

1996-12-03

Mackey, James P.

Plastic article or earthenware shaping or treating: apparatus

Preform reshaping or resizing means: or vulcanizing means...

Rod or tubular preform

405154, 425 11, B29C 6334, F16L 5518

Patent

active

055805892

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to apparatus for bending plastic pipe.
Equipment is known by which a polyethylene pipe is pulled through a die and through a host pipe, for example a gas main. The die reduces the diameter of the polyethylene pipe which, when the pulling force is removed, recovers its diameter and becomes a close fit within the host pipe. Such equipment was also used in which a pipe pusher was incorporated, the pusher repeatedly gripping the pipe and pushing the pipe into the host pipe.
In the known equipment, the host pipe was required to react to the bending of the polyethylene pipe as it entered the host pipe. This added to the frictional resistance and the total force required to pull the polyethylene pipe through the host pipe.
The invention provides apparatus for bending plastic pipe which is useful in methods in which the plastic pipe is passed into a host pipe whether the plastic pipe is first reduced in diameter by passing it through a die or alternatively the plastic pipe is installed in the host pipe as a loose liner.


SUMMARY OF THE INVENTION

Apparatus for bending plastic pipe before it enters a host pipe, according to the invention, comprises a structure which is elongated in a direction in which, in use, plastic pipe enters host pipe and which has a first end and a second end, anchorage means for securing said elongate structure to an entry end of a host pipe and pivotally connected to said structure at said second end thereof about a first horizontal axis, first, second and third guides intended for engagement, respectively, with an under surface, a top surface and the under surface of said plastic pipe, said first guide being mounted on said structure at said first end thereof, said third guide being mounted on said structure of said second end thereof and said second guide being mounted on said structure intermediate said first and third guides, said guides being profiled to accommodate said plastic pipe and said second guide being adjustable between an upper retracted position and a lower working position, and means connected to said structure engageable with the ground and adjustable for setting the inclination, relative to the ground, of said structure about said first horizontal axis ,


BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the apparatus will now be described with reference to the accompanying drawings in which:
FIG. 1 is a plan of a first embodiment of apparatus useful where the diameter of the plastic pipe is reduced by passing the pipe through a die;
FIG. 2 is a side elevation of the apparatus shown in FIG. 1; and
FIGS. 3 and 4, 5 and 6, 7 and 8 and 9 and 10 correspond to FIG. 1 but show second, third, fourth and fifth embodiments, respectively, useful where the pipe is installed as a loose liner in a host pipe.


DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 and 2 show a pipe 10 of polyethylene being passed through a die 12 and then into a host pipe 14 which is a former gas main. The pipe 10 is reduced in diameter by the die 12 and when it is fully inserted in the host main 14 the pulling force applied to the leading end of the pipe 10 is removed. The pipe 10 progressively recovers its diameter and eventually is a close fit within the host pipe 14. The host pipe 14 is shown having been exposed by an excavation in the earth. The pipe 14 has had a section removed from it and the other end of the pipe is shown to the right in FIG. 2.
FIGS. 1 and 2 show a structure 20 which is elongated in the direction in which the pipe 10 passes through the die 12. The die 12 is pivotally mounted on one end of the structure 20 (the first end) about a horizontal axis 22.
The other end of the structure 20 (the second end) is pivotally connected about a horizontal axis at 24 to anchorage means 26. The anchorage means 26 is secured to the protruding end of the host main 14. The anchorage means 26 carries a horizontal roller 28 which engages the under surface of the pipe 10 (see FIG. 2).
The anchorage means 26 also carries another horizontal roller 29 (see F

REFERENCES:
patent: 4504171 (1985-03-01), Florence, Jr.
patent: 4668125 (1987-05-01), Long, Jr.
patent: 4898498 (1990-02-01), Akesaka
patent: 4998871 (1991-03-01), Ledoux
patent: 5092756 (1992-03-01), Gau et al.
patent: 5114634 (1992-05-01), McMillan
patent: 5340524 (1994-08-01), McMillan et al.
patent: 5348459 (1994-09-01), Sauron et al.

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