AU2006299741B2 - Pipe cutter - Google Patents

Description

1 INTERNAL PIPE CUTTER FIELD OF INVENTION THIS INVENTION relates to cutting all types of pipe, and in particular to cutting these pipes in restricted areas. 5 BACKGROUND ART There are occasions when a pipe needs to be cut when it is either closely adjacent a surface through which it passes or even below the surface at which it is located and it has been conventionally effectively impossible to do this or, at 0 least to do it neatly and without likely damage to the surface or surround and then incurs reparation works. An object of the invention is provide a means whereby a pipe can be cut from the interior thereof so that the actual location, of the pipe is not of relevance as far as being able L5 to cut the pipe. DISCLOSURE OF THE INVENTION The invention, in its broad sense, includes a tool for cutting a pipe from the inside which includes an elongate body to which there is fitted a cutter heads having a number of 0 cutters which are moveable radially and means whereby the cutters can be forced to move radially outwardly on being contacted by a drive rod.

2 In a preferred form of invention the drive rod is connected to a source of rotating power and is in itself driveably connected to the tubular body so that on rotation of the power source the body and the cutter head are caused to 5 rotate, the arrangement being such that during such rotation an inward force on the rod causes the outward movement of the cutters. It is preferred that there is an adjustment plate moveable along the body and retainable in required positions 0 therealong which can act against an outer surface of the pipe being cut which provides an accurate spacing of the cut from the external surface of the pipe and a restraining means against the inward source can act. BRIEF DESCRIPTION OF THE DRAWINGS 5 In order that the invention can be more readily understood one particular embodiment of the pipe cutter is described with reference to the accompanying drawings, in which: Fig. 1 is a part-sectional side view of a pipe cutter 20 according to the invention; Fig. 2 is a sectional view of a cutter head for the pipe cutter of Fig. 1; 3 Fig. 3 is a sectional view of the cutter head for the pipe cutter of Fig. 1, the section being orthogonal to that of Fig. 2; Fig. 4 is a side view partly cut away of a driving rod 5 assembly for the pipe cutter of Fig. 1; Fig. 5 is a side view, partly cut away, showing the assembly of the cutter head of Figs. 2 and 3 attached to the driving rod assembly of Fig. 4. DETAILED DESCRIPTION OF THE DRAWINGS 0 The pipe cutter 10 has a cutter head 11 attached to the end of a driving rod assembly 12 and a pushing plate 13 penetrated by the driving rod assembly. While the dimensions of the cutter head are not critical to the invention, it is necessary that the diameter of the head cutter head be less 5 than the internal diameter of the smallest pipe in respect of which it is to be used. The driving rod assembly includes a drive shaft 14 passing through a tube 15 and located, preferably, at least adjacent each end thereof the drive shaft extends outwardly 20 from the tube to provide projected portions 16 and 17. The projected portion at 16 includes a power connection formation 18 which may be connected to a power source, such as a power drill. For convenience, the end of the drive shaft at the 4 power connection formation will be referred to as the power connection end. The drive shaft is hexagonal in section, but may be square or otherwise shaped in cross section and has a tapered free end 19 on the projected portion at 17. The power 5 connection end and free end terminology will likewise refer to the corresponding ends of the tube. A washer 20 is fixed on the drive shaft spaced from the free end of the tube which washer is adapted to act as a stop for a helical spring the other end of which can react against 0 one of the location members or a further apertured member which is connected to the main drive tube so that the shaft, in its rest position, is directed outwardly relative to the tube in the direction of arrow 21 but can be moved axially within the limits of movements provided by the spring. 5 Connected to the lower end of the tube there is the cutter head which has a number of cutters (minimum of two) preferably four which are radially located in the body which have cutting surfaces on their outer edges and which are spring biased by cutter head springs 22 to be normally within 20 the periphery of the cutter head and at this position are spaced at the inner ends by the distance such as to enable them to cooperate with the tapered end of the shaft and to be moved outwardly against their spring bias when the shaft is moved axially relative to the four inner ends.

5 That is, as the shaft is moved downwardly in the tube the tapered end enters the space bounded by the cutters and on further downward movement the blade cutters move outwardly beyond the periphery of the cutter head and, provided the 5 cutter head is rotating whilst the outward pressure is being applied, the cutters can cut off the pipe internally in which the cutter head is located. The pushing plate is located around the tube and is adapted to be moved along the tube and locked into position by 0 locking rings 23 which may be threadably connected to a thread on the outside of the tube whereby the location of the pushing plate along the length of the tube can be selected and locked in place. The operation of the pushing plate is that the required cutter head is attached to the tube, by a bayonet 5 fitting 24 thereon and the position of the cut is ascertained from the end of the pipe which is to be cut and the locking ring is located upon the tube at a position so that the pushing plate associated with this contacts the outer surface of the pipe at the required distance therealong. 0 A drill is then connected to the power connection end of the shaft and, on rotation of the drill, the shaft, the tube and the pushing plate rotate together, because of the shape of the shaft coacting with the apertures in the location members fixed to the tube. An inward pressure on the shaft (against 6 the direction of arrow 21) causes the shaft to move axially relative to the rotating tube, whereby the tapered end of the shaft enters the space between the cutters and causes the cutters to be moved outwardly. The outward movement can 5 continue with further downward pressure on the shaft until the pipe is cut. When the rotation of the drill ceases then the rotation of the tube and the cutter head also ceases and as the inward pressure by the drill is removed the shaft is moved back by its spring, the tapered end moves from the position 0 between the cutters, and the cutters retract via the cutter springs and are retained within the cutter body. It will be seen that the pipe cutter of the invention enables a quick and efficient means of cutting pipes from the interior thereof so that there is no part of the cutting 5 mechanism, except ultimately the tips of the cutters which extend beyond the pipe to be cut and as such there is no likelihood of damage. There are occasions when a pipe needs to be cut when it is either closely adjacent a surface through which it passes or even below the surface at which it is 20 located and it has been conventionally effectively impossible to do this or, at least, to do it neatly and without likely damage to the surface or surround. If it is required to cut off a pipe below a surface this can readily be achieved in a neat and workman like manner without requiring reparation ?5 work.

Claims (12)

1. A device to cut a pipe from its interior surface in an outward direction, said device including: a hollow tubular body adapted at one end for releasable attachment to a cutter head; cutting means connected to said cutter head, said cutting means capable of being biased against said interior surface for cutting thereof; and a driving member within, and operably connected to, said tubular body enabling rotation of said body, said driving member further being biased to move in a longitudinal direction when pressure is applied to one end of said driving member sufficient to engage and subsequently maintain said cutting means against said interior surface until said pipe is cut through.

2. A device as defined in Claim 1 wherein, said cutting means comprises a multiple of cutters, arranged circumferentially within said cutter head.

3. A device as defined in Claim 2 wherein, said driving member is adapted to enter centrally between said multiple of 8 cutters when said pressure is applied to bias said multiple cutters against said interior surface.

4. A device as defined in Claim 3 wherein there are two of said cutters.

5. A device as defined in Claim 3 wherein there are four of said cutters.

6. A device as defined in any one of Claims 2 to 5 wherein, each of said multiple cutters is a rotatable wheel with a cutting edge on the periphery of said wheel.

7. A device as defined in any one of Claims 1 to 6 wherein, said tubular body has a threaded exterior surface to accommodate a complementary internally threaded plate which can be rotated on said tubular body to bear upon an exposed end of said pipe to provide a depth guide for said cutting means to cut said pipe at a required location.

8. A device as defined in Claim 7 wherein, said plate is held in a required position on said threaded surface by one or more locking rings. 9

9. A method to cut a pipe from its interior surface in an outward direction, said method including: providing a device as defined in any one of Claims 1 to 8 with a said cutter head selected appropriate for the internal diameter of said pipe to be cut; placing said device into the interior of said pipe at a required depth for said cut; and applying said pressure to engage said cutting means against said interior surface while applying rotational motion to said driving member until said pipe is cut through.

10. A method as defined in Claim 9 wherein, said rotational motion is supplied by a powered drill operably connected to said driving member.

11. A device substantially as hereinbefore described with reference to the accompanying drawings.

12. A method substantially as hereinbefore described with reference to the accompanying drawings.