GB2582924A - Boring device - Google Patents

Abstract

A pipe boring device (in the form of a self-tapping ferrule strap) comprising a housing 101 having a tubular body 102, 103, with a base (120) for engaging a pipe, a bore (123) extending from the base into the tubular body with a cutter 105 received therein for boring a hole in a pipe, a fluid passageway 128 at least partially surrounding the bore and an outlet for connecting the fluid passageway with a branch pipe, wherein the base comprises one or more transfer passages 126 external of the bore which provide, in use, fluid communication between the fluid passageway and a hole formed in the pipe by the cutter. The one or more transfer passages external of the bore allows for effective extraction of fluid from a pipe to a branch pipe. The transfer passages may therefore be said to bypass the bore. Extraction of fluid is possible almost immediately after the cutter has been retracted from the bored hole. The use of transfer passages external of the bore also eliminates the need for radial holes.

Description

BORING DEVICE

This invention relates generally to boring devices and more particularly to boring devices for boring into pipes. More specifically, although not exclusively, this invention relates to pipe straps incorporating self-tapping ferrules for making a fluid connection through the wall of a pipe.

Self-tapping ferrule straps are generally formed of cast gunmetal and sized to suit a particular pipe diameter. These straps are formed in two, part-circular castings that are io wrapped around opposite sides of the pipe and bolted together. Whilst such arrangements are fit for purpose, they are bulky, expensive to manufacture and provide minimal adjustment.

Adjustable self-tapping ferrule straps are also known, which consist of a single casting to is which a steel strap is secured at one side. The strap has a portion near its free end having spaced holes for selective engagement with a fastener on the other side of the casting. This arrangement can accommodate a wide array of pipe sizes, but the free end of the strap can present a safety hazard.

zo W02016083786 seeks to remedy this problem by providing a strap with a pair of strap portions connected together at a first of their ends, wherein a first strap portion has a slot and the second strap portion has hooks spaced along its length. When the strap is wrapped around a pipe, the first strap portion overlaps the second strap portion such that one of the hooks is received in the slot, extends through the first strap portion and is in engagement with the end of the slot.

However, the boring device, whilst a separate component, is still formed of a conventional tubular gunmetal housing surrounded by a banjo fitting. The housing has a threaded bore which receives a cutter for making the hole and radial holes in the tubular wall that allow fluid to flow from a hole made in the pipe into the banjo fitting to provide a branch off the pipe. This presents a number of design constraints, requiring multiple configurations to accommodate different applications.

It would therefore be desirable to provide a boring device that mitigates the issues with known boring devices. It would also be desirable to provide a boring device that is able to accommodate a greater range of applications.

According to a first aspect of the invention, there is provided a pipe boring device comprising a housing having a tubular body with a base, e.g. for engaging a pipe, a bore extending from the base into the tubular body with a cutter received therein for boring a hole in a pipe, a fluid passageway at least partially surrounding the bore and an outlet for connecting the fluid passageway with a branch pipe, wherein the base comprises one or more transfer passages external of the bore which provide, in use, fluid communication between the fluid passageway and a hole formed in the pipe by the cutter.

The provision of one or more transfer passages external of the bore allows for more effective extraction of fluid from a pipe than in the previous designs. In conventional boring devices, as described above, the cutter inhibits the flow of fluid from the hole in the pipe to the radial holes until it is fully retracted. The length of the housing is therefore a function of the required travel of the cutter, which must be long enough to cut through the pipe wall and to retract fully relative to the radial holes. The transfer passages may therefore be said to bypass the bore.

In the case of the present invention, however, extraction of fluid is possible almost immediately after the cutter has been retracted from the bored hole. Further, the present invention provides for a more effective flow path for extracted fluid from the pipe to a branch pipe, allowing for a greater volume of fluid to be extracted more easily.

The bore and/or the cutter may comprise a thread or threaded portion, which may cooperate such that rotation of the cutter causes it translate along the bore. The Applicant has found that the use of transfer passages external of the bore also eliminates the need for radial holes. It is believed that the regions between these radial holes were subjected to much higher stresses in conventional housings, as the cutter penetrates the pipe.

Additionally, the reduced local surface area of the bore between the radial holes causes an increase in friction between the threads of the cutter and the threads of the bore as the cutter translates across the radial holes. This is undesirable as greater force must be applied to cut through the pipe wall.

The bore and/or the cutter may comprise a thread having a pair of flanks, for example a first flank and a second flank. The angle between the first flank and an axis, e.g. longitudinal axis, of the bore or cutter may be different to, for example steeper than, the angle between the second flank and the axis. The first flank of the bore may face the base, while the second flank of the bore may face away from the base. The second flank of the cutter may face a cutting end thereof, while the first flank of the bore may face away from the cutting end.

The first flank of the cutter may engage the first flank of the bore and/or the second flank of the cutter may engage the second flank of the bore. The first flank may comprise a leading flank and/or the second flank may comprise a trailing flank. The trailing flanks may be steeper than the leading flank, for example to resist inadvertent retraction of the cutter into the bore and/or to improve the stress distribution along and/or across the threads. As used herein, the terms leading and trailing refer to the direction of movement of the cutter as it bores, in use, a hole in the pipe.

The device or base may comprise a pipe facing surface, which may include an inlet chamber. At least one or the transfer passage may fluidly connect the inlet chamber to the fluid passageway. The inlet chamber may be configured to allow or facilitate the flow of fluid from a pipe into the transfer passage(s), for example when the cutter is retracted from the pipe.

The pipe boring device may be configured such that at least part of a pipe-facing side or surface of the base stands proud, in use, of the pipe, e.g. to provide the inlet chamber. The inlet chamber may be provided at least in part by a recess formed in the base. The or a pipe-facing side or surface of the base may comprise the recess. At least a portion of the recess may comprise an annular recess, for example surrounding or circumscribing the bore.

The device may comprise a sealing means or seal extending about the inlet chamber. The inlet chamber may be provided at least in part by the sealing means or seal. The sealing means or seal may stand proud of and/or protrude from the base, e.g. such that the base is spaced, in use, from a pipe to which the device is mounted and/or so as to describe at least part of the inlet chamber. The sealing means or seal may extend about the bore and/or the transfer passage(s) and, if present, the recess. The seal may comprise an annular seal. The annular seal may be received or seated within the annular recess The device may comprise a plurality of transfer passages, which may be spaced, e.g. circumferentially spaced, about the bore. The transfer passages may provide a segmented flow path, e.g. a segmented annular flow path. The transfer passages may at least partially surround the bore and/or may be separated by webs.

At least one of the transfer passages may be substantially elliptical or pseudo-elliptical, lenticular, substantially trapezoidal, substantially rectangular or pseudo-rectangular, e.g. in cross-section. At least one of the transfer passages may be curved or substantially arcuate, e.g. in cross-section, for example so as to provide a composite annular flow path. The transfer passages may comprise or provide a segmented annular flow path, which may surround the bore.

The housing may comprise an inner part, which may comprise a stem, and/or an outer part, which may comprise a banjo fitting. The outlet may comprise a push-fit connector. The inner part may comprise the bore and/or the base. The base may comprise a saddle and/or may be saddle-shaped. The inner part may comprise an annular recess, which may describe part of the fluid passageway. The transfer passage(s) may extend from the or a pipe-facing side of the base to the annular recess. The inner part may comprise one or more, e.g. a pair of, sealing annuli. The annular recess may be described between the sealing annuli.

The transfer passage(s) may extend through the base. The outer part may be arranged to receive the inner part, for example to describe the fluid passageway therebetween.

The inner and outer parts may be connected, e.g. sealingly connected, by sealing means, which may be annular and/or circumferential. The sealing means may comprise one or more, e.g. a pair of, seals or annular seals. The or at least one of the seals may be received in a recess or groove, e.g. a circumferential groove, in or of the inner or outer part. The inner part may comprise one or more, e.g. a pair of, sealing annuli. The or each sealing annulus may protrude or project from the inner part, e.g. the or a stem or stem portion thereof. The or each sealing annulus may comprise the recess or groove.

The pair of sealing annuli may be on either side of the fluid passageway. A first sealing annulus may be on or located on a first side of the fluid passageway. A second sealing annulus may be on or located on a second side of the fluid passageway, e.g. opposite the first side. The pair of seals may be received in respective recesses either side of the fluid passageway. A first seal may be received in a recess on a first side of the fluid passageway.

A second seal may be received in a recess on a second side of the fluid passageway, e.g. opposite the first side. The recess(es) and/or sealing annuli may be circumferential and/or the seal(s) may comprise circumferential seals. The or at least one of the seals may comprise an 0-ring or a gasket.

The device may comprise an end cap, which may be mounted to the housing or inner part, e.g. for retaining the outer part thereon. The end cap may be retained on the housing or inner part, for example by a bayonet fitting. The base may be at a first end of the housing or inner part. The end cap may be mounted to a second end of the housing or inner part.

The inner part may comprise one or more projections at or adjacent one of its ends, e.g. the second end or an opposite end to the base. The projection(s) may be lateral or radial projections and/or extend laterally or radially of the inner part and/or bore. The inner part may comprise a castellated, for example a laterally or radially castellated, end. The inner part may comprise a splined end.

The end cap may comprise one or more recesses for receiving and/or engaging the projection(s), castellations or splines of the inner part. The end cap may comprise one or more legs, tabs, ledges or lips, which may provide the recess(es), e.g. for receiving and/or engaging the projection(s). The end cap may comprise a plurality of recesses, legs, tabs, ledges or lips, which may be spaced, e.g. circumferentially spaced.

The end cap may be configured to be placed over the inner part, e.g. such that the projection(s), castellations or splines thereof pass through the spaces between the recesses, legs, tabs, ledges or lips, and rotated. The end cap may be configured to be rotated from an unlocked position, condition or orientation, e.g. in which the projection(s), castellations or splines of the inner part are aligned with the spaces, to a locked position, condition or orientation, e.g. in which the projection(s), castellations or splines of the inner part engage the recesses, legs, tabs, ledges or lips.

The device or housing or inner part may comprise an opening, which may be at the or an opposite end to the base, for example the second end, which may be for inserting a tool to drive the cutter. The cutter may comprise a first end, e.g. a driving end, and/or a second end, e.g. a cutting end. The first end may be threaded or comprise a thread. The cutter may comprise a substantially constant size or diameter. The first end may have substantially the same diameter or cross-section as the second end. The cutter or first end thereof may comprise a socket, recess, keyway, projection or key, e.g. for receiving and/or engaging a tool for driving the cutter. The cutter or second end thereof may comprise a tubular cutting member having a sharp and/or slanted or sloped edge. The cutter or tubular cutting member may comprise a pair of substantially axial slots, which may be slanted relative to the longitudinal axis of the cutter and/or which may describe or delineate or divide the tubular cutting member into a pair of cutting blades. The device or housing or inner part may comprise a shoulder, which may be described between the bore and the opening. The device or housing or inner part may comprise a seal means, e.g. an annular seal means, io which may be captivated between the shoulder and the cutter. The seal means may comprise a seal or washer or gasket.

The inner part may be formed of a stronger and/or more rigid material than the outer part. The inner part may be formed of metal, e.g. gunmetal. Alternatively, the inner part may be formed of an engineered plastics material. Additionally or alternatively, the outer part may be formed of metal, e.g. gunmetal, but is preferably formed of an engineered plastics material.

The device may comprise a strap, e.g. for securement around a pipe and/or to enable a hole to be bored into the pipe. The strap may comprise first and second strap portions, which may be connected together, e.g. at a respective first of their ends. One of the strap portions may comprise a receptacle within which the housing is received. The receptacle may comprise at least one, e.g. a pair of opposed, retaining tab(s), which may engage a notch or respective notches in the housing, e.g. to retain the boring means within the receptacle. The strap portions may be connected together by connection means, for example adjustable connection means, which may be for adjusting the relative position of the connected first ends. The strap portions may be pivotally connected together by the connection means.

The connection means may comprise screw threaded adjustment means, e.g. for selectively drawing the strap portion ends together. The connection means may comprise a screw threaded fastener engaging a pair of pins. Each strap portion may comprise a loop, e.g. at or adjacent its connected end, with one of the pins rotatably received therein. Each loop may comprise a circumferential slot, for example through which the fastener extends, such as to enable the strap portions to pivot relative to one another.

The first strap portion may comprise a recess, aperture or slot, which may be at or adjacent a second, free end thereof. The second strap portion may comprise one or more projections or hooks, which may be spaced along its length. The strap may be configured to be wrapped, in use, around a pipe with the first strap portion overlapping the second strap portion, for example wherein the or one of the projection(s) or hook(s) is received in the recess, aperture or slot and may be in engagement therewith. The projection(s) or hook(s) may extend through the first strap portion and/or be in engagement with the end of the recess, aperture or slot.

The strap may define an opening that is at least partially dependent upon which of the projections or hooks is in engagement with the recess or aperture. When the first strap portion overlaps the second strap portion, the second strap portion may be between the first strap portion and the pipe. The first strap portion may comprises a pair of slots. The second strap portion may comprise two or more hook pairs. Each hook pair may be spaced along the length of the second strap portion, for example such that the strap defines an opening that is dependent upon which of the hook pairs is in engagement, in use, with ends of the slot pair.

The strap portions may be formed from sheet material, e.g. sheet metal or sheet steel. The or each projection or hook may comprise a deformed portion of sheet material. The device may comprise a self-tapping ferrule strap.

Another aspect of the invention provides a kit of parts for assembly into a boring device, for example a boring device as described above. The kit may comprise the housing and the cutter. The kit may comprise the inner part and/or the outer part of the housing. The kit may further comprise the strap, for example the first and second strap portions.

For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention. For example, the kit may comprise any one or more features of the device relevant thereto and vice versa.

Another aspect of the invention provides a computer program element comprising and/or describing and/or defining a three-dimensional design for use with a simulation means or a three-dimensional additive or subtractive manufacturing means or device, e.g. a three-dimensional printer or CNC machine, the three-dimensional design comprising an embodiment of one or more of the components of the device described above.

A further aspect of the invention provides the computer program element embodied on a computer readable medium.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms "may", "and/or", "e.g.", "for example" and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a section view of the pipe boring device according to the prior art; Figure 2 is a perspective view of a pipe boring device according to an embodiment of the invention; Figure 3 is an exploded view of the pipe boring device of Figure 2; Figure 4 is a perspective view of the inner part of the housing of the boring device of Figures 2 and 3; Figure 5 is a perspective view of the inner part of Figure 4 from below; Figure 6 is a side view of the cutter of the boring device of Figures 2 and 3; Figure 7 is a perspective view of the cutter of Figure 6 showing the drive socket; and Figure 8 is a section view of the pipe boring device of Figures 2 and 3.

Referring to the Figure 1, there is shown a boring device 1 in the form of a self-tapping ferrule strap 1 according to the prior art, which is to be wrapped around a pipe (not shown). The device 1 includes a housing 10, which includes an inner part 2, an outer part 3 and an to over cap 4. The inner part 2 threadedly receives a cutter 5 for boring a hole into a pipe (not shown). The device 1 also includes an outer strap portion 6 and an inner strap portion 7, which are connected together by a connector 8.

The inner part 2 is similar to that shown in W02016083786, the contents of which are incorporated herein by reference. More specifically, the inner part 2 includes a saddle portion 20, an intermediate portion 21 and a stem portion 22 with a threaded axial bore 23 extending through all three portions 20, 21, 22.

The saddle portion 20 extends outwardly from the intermediate portion 21 to provide a shoulder 24 and includes a curved bottom surface 25 shaped to conform the outer surface of the pipe (not shown), which lower surface 25 has an 0-ring seal 25a received in a circular groove surrounding the bore 23 for sealing against the pipe (not shown). The intermediate portion 21 is cylindrical in shape, projects upwardly from the shoulder 24 of the saddle portion 20 and includes a pair of notches 26. The stem portion 22 includes an external thread 27 extending along part of its length from its upper end, a transverse or radial bore 28 through a lower part extending through and in communication with the axial bore 23 and radial flanges, one of which is above and another below the radial bore 28.

The outer part 3 is in the form of a banjo fitting 3, which includes an annular portion 30 that surrounds the stem portion 22 of the inner part 2, a radial spigot 31 projecting from one side of the annular portion 30 and a push fit assembly 32 threadedly secured to the radial spigot 31. The radial spigot 31 includes an internal step that receives an annular seal 33 and a top hat-shaped seal retainer 34 of the push fit assembly 32.

The push fit assembly 32 also includes a tapered, split clamp ring 35 captivated between the seal retainer 34 and a push fit cap 36 threadedly secured to the radial spigot 31. The push fit assembly 32 functions in a known manner by allowing a pipe (not shown) to be inserted into an open end of the push fit cap 36 to a position in which the annular seal 33 seals against an outer surface thereof, wherein removal of the pipe (not shown) is inhibited by the cooperation between the tapered, split clamp ring 35 and a tapered facing surface of the push fit cap 36.

The annular portion 30 of the outer part 3 includes an inwardly facing lip 37 at its lower end to and an internal step 38 at its upper end. The lip 37 includes an internal step in its lower surface within which is received an annular seal 39a. The outward step 38 also receives an annular seal 39b.

The over cap 4 includes a first, closed end 40 with a hole 41 through its thickness that is covered by a cap member 42. The over cap 4 also includes an internal bore 43, part of which is threaded, and an outer flange 44 adjacent its open end. The over cap 4 is mounted to the inner part 2 such that the threaded portion of the internal bore 43 engages the external thread 27 of the stem portion 22.

The annular portion 30 of the outer part 3 is captivated between the over cap 4 and the intermediate portion 21 of the inner housing part 2. More specifically, the open end of the over cap 4 engages the annular seal 39b in the outward step 38 at the upper end of the annular portion 30 and urges the annular seal 39a received in the internal step of the lip 37 at its lower end against the end of the intermediate portion 21 adjacent the lower radial flange of the inner part 2. This arrangement provides a compression, face seal-type sealing arrangement that is typical in such bayonet fittings. In addition, an annular sealing washer 45 is captivated and sealing compressed between the closed end 40 of the over cap 4 and the upper end of the inner part 2.

The inner part 2 also receives a self-tapping ferrule insert or cutter 5, which includes an enlarged head 50 at a first end and a tubular cutting member 51 projecting from the head 50. The head 50 is threaded externally and includes a hexagonal socket for receiving a hexagonal tool (not shown) to drive the cutter 5 in use. The tubular cutting member 51 includes a pair of substantially axial slots, which are slanted slightly relative to the longitudinal axis of the cutter 5 and divide the tubular cutting member 51 into a pair of cutting blades. Each cutting blade of the cutting member 51 has a sharp, part-circumferential free edge that is slanted to provide a cutting edge in the usual way.

In use, the cap member 42 of the over cap 4 is removed to reveal the hole 41. A hexagonal removal tool (not shown) is inserted into the hole 41 and into the hexagonal socket 53 of the cutter 5. The tool (not shown) is rotated to drive the cutter 5 down to cut into the pipe (not shown). The tool (not shown) is then rotated in reverse to withdraw the cutter 5 out of the hole bored in the pipe (not shown). As the cutter 5 is withdrawn, fluid flows from the pipe (not shown) into the clearance between the undersized tubular cutting member 51 and io the threaded axial bore 23 of the inner part and out of the radial bores 28. Further retraction of the cutter 5 reduces the restriction of flow therepast until the cutter 5 is fully retracted. In the fully retracted position, the head 50 of the cutter 5 seals against the sealing washer 45 to fully seal the device 1.

Turning now to Figures 2 and 3, there is a shown a boring device 100 according to an embodiment of the invention. The boring device 100 according to this example includes a housing 101 having an inner part 102, an outer part 103 and an end cap 104. The inner part 102 threadedly receives a cutter 105 for boring a hole into a pipe (not shown). The device 100 also includes an outer strap portion 106 and an inner strap portion 107, which are connected together by a connector 108.

The inner part 102, shown more clearly in Figures 4 and 5, includes a base 120 with a stem 121 projecting therefrom, a castellated or splined end 122 and a threaded axial bore 123 open through the base 120 and extending to a hole 122a through the splined end 122. The diameter of the hole 122a is smaller than that of the threaded axial bore 123, thereby providing a shoulder 122b.

The base 120 includes a saddle portion 124 projecting outwardly in a similar manner to the saddle portion 20 of the boring device 1 of the prior art, but with differences that will be apparent from the present disclosure. The base 120 also includes a first sealing annulus spaced from the saddle portion 124 and six transfer passages 126 surrounding the axial bore 123 and providing a segmented annular flow path therearound.

The saddle portion 124 also includes first and second recesses 124a, 124b in its lower surface. The first recess 124a is substantially cylindrical and coincides with the outer dimension of the transfer passages 126 to describe an inlet chamber 124a. The second recess 124b surrounds the first recess 124a and receives an 0-ring seal 124c for sealing against the pipe (not shown).

The first sealing annulus 125 is in the form of a flange projecting outwardly of the base 120 and including a circumferential groove 125a, which receives an 0-ring seal 125b. The transfer passages 126 extend from the inlet chamber 124a through the base 120 and open through an upper surface of the first sealing annulus 125. The transfer passages 126 have a curved, substantially rectangular cross-section with rounded corners and are separated io by webs 126a, which connect the base 120 to the stem 121.

The stem 121 includes a second sealing annulus 127 adjacent to, but spaced from, the splined end 122. The second sealing annulus 127 is also in the form of a flange, projects outwardly of the stem 121 and includes a circumferential groove 127a, which receives an 0-ring seal 127b. The diameter of the second sealing annulus 127 is smaller than that of the first sealing annulus 125, as are their respective 0-ring seals 125b, 127b.

The outer surface 128 of the stem 121 between the first and second annuli 125, 127 is recessed to describe part of a fluid passageway surrounding the axial bore 123. As a result, the transfer passages 126 extend from the inlet chamber 124a through the base 120 and open into this fluid passageway.

The splined end 122 includes four radial projections, castellations or splines 122c spaced equally about its periphery and projecting outwardly therefrom. Each spline 122c is substantially arcuate and the circumferential extent of each is substantially the same as the circumferential extent of the spaces between them.

The outer part 103 is in the form of a banjo-type fitting 103, which includes an annular portion 130, a radial spigot 131 projecting from one side of the annular portion 130 and a push fit assembly 132 threadedly secured to the radial spigot 131. The annular portion 130 is hollow, substantially cylindrical and is stepped to provide an upper internal surface 130a having a reduced diameter. The annular portion 130 also includes a shallow internal step 130b adjacent its lower end. The push fit assembly 132 is similar to the push fit arrangement described in GB2521825A, the contents of which are incorporated herein by reference, and will therefore not be described in further detail herein.

The end cap 104 is substantially cylindrical with a side wall 140, an end wall 141 and four ledges 142 projecting inwardly from the side wall 140. The shape of the ledges 142 corresponds substantially to that of the splines 122c of the inner part 102. The end wall 141 includes a central hole 143 through its thickness and four arcuate holes 144 inboard of the side wall 140 and aligned with the ledges 142. It will be appreciated that these arcuate holes 144 are necessary for forming the ledges 142 in a conventional injection mould tool (not shown).

to The annular portion 130 of the outer part 103 surrounds the inner part 102 and is retained thereon by the end cap 104. To secure the end cap 104 to the inner part, it is first placed over the splined end 122 of the inner part 102 with the ledges 142 aligned with the spaces between the splines 122a until the splined end 122 of the inner part abuts the end wall 141. The end cap 104 is then rotated through 45 degrees to lock the ledges 142 with the splines 122a in a bayonet-type fashion.

With the end cap 104 in place, the internal step 130b adjacent the lower end of the outer part 103 abuts the upper corner of the first sealing annulus 125. This locates the outer part 103 relative to the inner part 102. The 0-ring seal 125b sealingly engages the inner surface of the annular portion 130 immediately below the internal step 130b. Similarly, the 0-ring seal 127b sealingly engages the upper internal surface 130a of the outer part 103. An annular outlet passage 133 is described between the outer surface 128 of the stem 121 and the annular portion 130. This annular outlet passage 133 is fluidly connected to the inlet chamber 124a via the transfer passages 126 and feeds, in use into the radial spigot 131 and out of a pipe (not shown) connected to the push fit assembly 132.

This arrangement differs from the sealing arrangement of the device 1 of the prior art in that, inter alia, sealing is achieved using circumferential seals 125b, 127b. Contrary to the face seal arrangement of the device 1 of the prior art, the use of circumferential seals 125b, 127b precludes the need to apply a preload using a threaded end cap 4. Instead, a simple bayonet fitting is sufficient. As such, the force required to secure the end cap 104 is less and the radial spigot 131 is able to rotate more freely. This arrangement also reduces the risk of leakage.

The cutter 105, shown more clearly in Figures 6 and 7, has a substantially constant diameter, with a first, threaded end 150 and a tubular cutting member 151 projecting from the first end 150. The first end 150 includes an external thread 152 and a hexagonal socket 153 for receiving a hexagonal tool (not shown) to drive the cutter 105 in use. The tubular cutting member 151 includes a pair of substantially axial slots 154, which are slanted slightly relative to the longitudinal axis of the cutter 105 and divide the tubular cutting member 151 into a pair of cutting blades 155. Each cutting blade 155 has a sharp, part-circumferential free edge 155a that is slanted to provide a cutting edge in the usual way.

to The cutter 105 is threadedly received within the axial bore 123 of the inner part 102, with a sealing washer 156 captivated between the first end 150 of the cutter 105 and the shoulder 122b of the inner part 102. As illustrated more clearly in Figure 8, the trailing flanks of the threads 152 of the cutter 105 and those of the axial bore 123 of the second part 102 are steeper than their leading flank. This arrangement has been found to resist inadvertent retraction of the cutter 105 into the bore 123 and to improve the stress distribution along and across the threads 152.

The strap portions 106, 107 are connected to one another at a first of their ends by a screw threaded fastener 180 which threadedly engages a pair of pins 181, 182, each of which is captivated within a respective loop 160, 170 of the strap portions 106, 107. The pins 181, 182, are rotatably received in the loops 160, 170 and each loop 160, 170 includes a circumferential slot 161, 171 through which the fastener 180 extends to enable the strap portions 106, 107 to pivot relative to one another. The inner strap portion 107 includes a hole or receptacle 170a which receives the base 120 of the inner part 102.

The outer strap portion 106 has a series of slot pairs 162, one pair of which has an engaging end 163 adjacent its second end. The inner strap portion 107 includes three pairs of hooks 172 spaced along its length. When the strap portions 106, 107 are wrapped around a pipe (not shown), the first strap portion 106 overlaps the second strap portion 107 and the hooks 172 are received in the slots 162. The hooks 172 extend through the slots 162 in the first strap portion 106 and one of the hook pairs 172 engages the slot end 163. The strap portion 106, 107 defines an opening that is dependent upon which of the hooks 172 are in engagement with the slot ends 163.

The strap portions 106, 107 are preferably formed of sheet steel and the hooks 172 are provided by a deformed portion of the inner strap portion 107. The strap portions 106, 107 and connector 108 are similar to the strap arrangement described in W02016083786, the contents of which are incorporated herein by reference.

It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear to advantages over the prior art and are therefore within the scope of the invention described herein.

Claims (17)

1. CLAIMSA pipe boring device comprising a housing having a tubular body with a base for engaging a pipe, a bore extending from the base into the tubular body with a cutter received therein for boring a hole in a pipe, a fluid passageway at least partially surrounding the bore and an outlet for connecting the fluid passageway with an branch pipe, wherein the base comprises one or more transfer passages external of the bore which provide, in use, fluid communication between the fluid passageway and a hole formed in the pipe by the cutter.
2. 2. A pipe boring device according to claim 1, wherein a pipe facing surface of the base comprises an inlet chamber and the transfer passage(s) fluidly connect(s) the inlet chamber to the fluid passageway, the inlet chamber being configured to allow the flow of fluid from a pipe into the transfer passage(s) when the cutter is retracted from the pipe.
3. A pipe boring device according to claim 2, wherein the pipe-facing side of the base comprises a recess describing at least part of the inlet chamber.
4. 4. A pipe boring device according to claim 2 or claim 3, comprising a seal extending about the inlet chamber.
5. 5. A pipe boring device according to claim 4, wherein the seal protrudes from the base such that the base is spaced, in use, from a pipe to which the device is mounted so as to describe at least part of the inlet chamber.
6. A pipe boring device according to any preceding claim, comprising a plurality of transfer passages spaced about the bore to provide a segmented annular flow path.
7. 7. A pipe boring device according to claim 6, wherein the passages are rectangular or pseudo-elliptical in cross-section and are separated by webs.
8. A pipe boring device according to any preceding claim, wherein the housing has an inner part and an outer part, the inner part comprising the bore and the outer part arranged to receive the inner part to describe the fluid passageway therebetween, wherein the inner and outer parts are sealingly connected by annular sealing means.
9. A pipe boring device according to claim 8, wherein the annular sealing means comprises a pair of annular seals received in respective recesses either side of the fluid passageway.
10. 10. A pipe boring device according to claim 8 or claim 9 comprising an end cap mounted to the inner part for retaining the outer part thereon.
11. 11. A pipe boring device according to claim 10, wherein the end cap is retained on the inner part by a bayonet fitting.
12. 12. A pipe boring device according to any one of claims 8 to 11, wherein the inner part comprises the base and an annular recess which describes part of the fluid passageway, the transfer passage(s) extending from the or a pipe-facing side of the base to the annular recess.
13. 13. A pipe boring device according to any preceding claim, wherein the housing comprises an opening at an opposite end to the base for inserting a tool to drive the cutter.
14. 14. A pipe boring device according to claim 13, comprising a shoulder described between the bore and the opening and an annular seal or washer captivated between the shoulder and the cutter.
15. 15. A pipe boring device according to any preceding claim, wherein the bore comprises a thread with a trailing flank that is steeper than the leading flank.
16. 16. A pipe boring device according to any preceding claim, wherein the outlet for connection with an branch pipe comprises a push-fit connector.
17. 17. A pipe boring device according to any preceding claim comprising an adjustable strap for securing the device to a pipe.