Pipe splitter and method

A pipe splitting assembly includes a pipe splitter, for instance, a cutter with one or more blades. An expander is flexibly coupled with the pipe splitter and allows the pipe splitter to rotate out of alignment with the longitudinal axis of the expander. In one example, the pipe splitter includes a cylindrical base portion and a frusto-conical base portion proximal to the cyclindrical base portion, and an exterior surface of the frusto-conical base portion is flush with an exterior surface of the expander. In another example, the expander has a larger outer perimeter than the cutter. Optionally, the pipe splitting assembly further includes a puller shoulder sized and shaped to couple with the expander, and a puller sleeve adapted to receive and hold a replacement pipe.

TECHNICAL FIELD

Pipe splitting and in particular assemblies for splitting pipes and positioning replacement pipes.

BACKGROUND

Pipe, such as plastic, copper, lead pipe and the like, has been used for connecting homes and creating networks for utilities, for instance, water, sewage and natural gas. As pipes become older, they break down, crack, develop scaling on interior surfaces that can clog the pipe, etc. and thereby require replacement.

A technique know as pipe bursting is currently used as a convenient method to replace underground pipe without the need to completely dig up the pipe to be replaced. A pipe breaking device, such as an expander or a mole, is pulled by a cable through the existing pipe while it is still underground. The expander is designed to break, split or burst the pipe, and at the same time to push the old pipe into the surrounding soil. The expansion of the old pipe allows the expander to pull a replacement pipe into place.

Pipe splitters typically use one or more cutting surfaces to split pipe material. Typically, the cutting surfaces engage against the end of the pipe and are pulled longitudinally to split the pipe. Large pulling forces are required to pull cutting surfaces with this configuration through the pipe material and thereby split the pipe. In some examples, where the existing pipe is located in soft soil, the pulling force transmitted from the cutting surfaces to the pipe will move the pipe through the soil instead of splitting the pipe material.

In other examples, pipe splitters are used to burst small diameter pipes and thereby must navigate tight bends in the pipe. An elongate pipe splitter experiences stress as it attempts to navigate tight bends and sometimes fractures within the pipe. This requires extraction and replacement of the pipe splitter to continue the operation. Replacement of the pipe splitter increases labor. Additionally, the pipe splitter is constructed with hardened steel in some examples, and is expensive. Replacing the pipe splitter thereby increases the cost of splitting small diameter pipes.

What is needed is a pipe splitter that provides consistent cutting without requiring excessive pulling forces. What is further needed is a pipe splitter capable of navigating bends in small diameter pipes without fracturing.

DESCRIPTION OF THE EMBODIMENTS

One example of a pipe splitting assembly100is shown inFIG. 1. The pipe splitting assembly100includes a pipe splitter, such as a cutter102. As shown inFIG. 1, in one example, the cutter102includes dual blades104. The blades104are sized and shaped to engage with a pipe and split the pipe. The cutter102includes a lumen extending therethrough sized and shaped to receive a flexible element, such as a cable106. In yet another example, the flexible element includes, but is not limited to a rope, rod, wire, band and the like.

An expander108is coupled with the cutter102. The expander108, in one example, has a lumen sized and shaped to receive the cable106. The cutter102and expander108lumens cooperate with the cable106to ensure the expander108and the cutter102maintain their arrangement along the cable106. The expander108has an outer perimeter larger than an outer perimeter of the cutter102. In another example, the expander108has a substantially frusto-conical geometry with a tapering profile that gradually increases in diameter from a distal end110of the expander108toward a proximal end111. The large outer perimeter of the expander108pries and bursts the split pipe apart to make room for a replacement pipe, as described below.

In one example, a distal end110of expander108is coupled with a proximal end112of the cutter102. As further described below, the cutter102and the expander108are flexibly coupled, for instance, with a flexible joint114. The flexible joint114permits rotation of the cutter102with respect to the expander108. Individually, the cutter102and the expander108have sufficiently short lengths to permit navigation through tight corners and elbows of pipes. The flexible joint114allows the cutter102and the expander108to cooperate in the pipe splitting assembly100and traverse tight corners and elbows together. For example, the cutter102is able to angle around tight corners and elbows in a pipe without becoming trapped. The expander108, coupled to the cutter102at the flexible joint114, follows the cutter102and angles through the tight corner or elbow.

Referring again toFIG. 1, the pipe splitting assembly100includes a puller shoulder116coupled with the expander108. In one example, the puller shoulder116has an outer perimeter similar to the outer perimeter of the expander108. In another example, the puller shoulder116has an outer perimeter smaller than the outer perimeter of the expander108. A bridge118extends from the puller shoulder116proximally. The bridge118and the puller shoulder116are integral, in yet another example. Optionally, the bridge118and the puller shoulder116are separate pieces and coupled together (e.g., with corresponding threading, bolts, welds, mechanical fittings and the like). As shown inFIG. 1, the bridge, in still another example, includes threading120. A puller sleeve122is coupled around the bridge118. The puller sleeve122and the bridge118cooperate to clamp a replacement pipe (e.g., replacement pipe121) between the bridge118and the interior surface of the sleeve122. Optionally, the threading120of the bridge118is a tap sized and shaped to cut corresponding threading into the interior of the replacement pipe121. The puller shoulder116, the bridge118and the puller sleeve122cooperate to clamp the replacement pipe121thereto and couple the replacement pipe121to the expander108. The puller shoulder116facilitates pulling of the replacement pipe121into the cavity formed by the cutter102and the expander108.

The pipe splitting assembly100is shown partially exploded inFIG. 2. A collet200is shown at an end202of the cable106. In another example, the collet200is placed at a point along a length of cable106, for instance between a winch at one end of a pipe to be split and a spool of cable at the other end of the pipe. The collet200is sized and shaped to grasp the cable106. As further described below, the collet200securely grasps the cable when the collet engages against an interior surface of the expander108. The collet200acts as a lug that transmits pulling forces from a winch, such as a capstan winch, to the expander108and the cutter102. In one example, pulling forces are transmitted from the collet200to the expander108, and the expander108transmits the pulling forces to the cutter102. The cable106thereby forces the cutter102and expander108to split the pipe and push it outwardly away from the cable106.

Referring again toFIG. 2, in one example, the puller shoulder116includes a fitting204sized and shaped to couple the puller shoulder116with the expander108. The fitting204includes, but is not limited to, threading, detents, mechanical locks and the like to securely couple the expander108with the puller shoulder116. For instance, as shown inFIG. 2, the fitting204includes threading and an interior surface of the expander108includes complementary threading to retain the coupling between the expander108and the puller shoulder116. In another example, the fitting204engages against the collet200and urges the collet to grasp the cable106prior to tensioning the cable. The secure coupling facilitates transmission of pulling forces through the collet200to the expander108and from the expander108to the puller shoulder116and the replacement pipe121. In another example, the pulling forces are transmitted from the puller shoulder116through the bridge118to the puller sleeve122and the pipe121.

The pipe splitter (e.g., cutter102) is shown inFIG. 3. The cutter102includes a base300sized and shaped to couple around the cable106, shown inFIG. 1. In one example, the cutter102includes a cutter lumen302sized and shaped to slidably receive the cable106. The cutter lumen302extends from a proximal end304to a distal end306of the cutter102. A longitudinal axis308of the cutter102extends through the cutter102, as shown inFIG. 3. When the cutter102is slidably coupled with the cable106, the longitudinal axis308is aligned with at least the portion of the cable106in the cutter lumen302. In another example, the base300includes a frusto-conical portion310and a cylindrical portion312distal to the frusto-conical portion310. As described above, the expander108(FIG. 1) includes a tapered profile. Optionally, the frusto-conical portion310of the cutter102provides a flush transition from the cutter102to the expander108when coupled together (SeeFIG. 1). The flush transition ensures that pipe split by the cutter102begins expanding because of engagement with the frusto-conical portion310and continues to expand when engaged with the expander108. Additionally, the flush transition substantially prevents the split pipe from snagging at the flexible joint114(FIG. 1). In yet another example, the cutter102has a frusto-conical geometry that tapers from the proximal end304to the distal end306. In still another example, the cutter102tapers from the proximal end304to the distal end306(e.g., a portion of the cutter102exterior is tapered and another portion is substantially flat).

In another example, the cutter102includes the blades104extending along the base300of the cutter. The blades104extend at an acute angle with respect to the longitudinal axis308. Optionally, the blades104extend at an angle of between less than 90 degrees and more than 0 degrees with respect to the longitudinal axis. In yet another example, the blades104gradually taper from the distal end306toward the proximal end304. The acute angle of the blades104engages the blades against the interior of a pipe to be split. As the cutter102moves down the pipe, the blades104apply greater pressure to the pipe interior and eventually split the pipe from the interior outwardly. Engaging the pipe along the interior facilitates cutting of the pipe without directly engaging a longitudinal end of the pipe. Even where the pipe is in loose soil or rock, the cutter102does not longitudinally move the pipe (e.g., toward the capstand winch) because the force that splits the pipe is substantially directed from the interior to the exterior of the pipe and not longitudinally. Moreover, less pulling force is required to cut the pipe with the blades104tapered than a cutting surface that directly engages the end of a pipe.

Optionally, the cutter102is constructed with a hardened material configured to cut through pipe (e.g., copper, lead, HDPE, PVC and the like). In one example, the cutter102is constructed with, but not limited to, hardened S7 tool steel and the like. In another example, the cutter102includes at least one of a variety of features configured to split a pipe. For instance, the cutter102includes, but is not limited to, serrations, a tapering profile, a single blade, a plurality of blades, a rotating cutting edge and the like. In one example, the tapering profile is repeatedly rammed into the pipe and the tapering profile splits open the pipe.

Referring again toFIG. 3, the cutter102includes a fitting314. In one example, the fitting314is round and extends from the proximal end304of the cutter102. The fitting314is received in a corresponding socket in the expander108(FIG. 1), as described below. The fitting314, in another example, is a ball received in the socket to form a ball and socket joint at the flexible joint114between the cutter102and the expander108, as shown inFIG. 1. The rounded fitting314allows the cutter102to rotate within the socket of the expander108, for example, during navigation of piping elbows. The fitting314facilitates rotation of the cutter102relative to the expander108. In another example, the fitting314forms part of a hinge, a universal joint and the like at the flexible joint114. In yet another example, the fitting extends from the expander108and the cutter102includes the socket.

Referring now toFIG. 4A, the expander108including the socket400is shown. The socket400is sized and shaped to receive the fitting314of the cutter102(FIG. 3). The socket400, in one example, includes a rounded surface that permits rotation of the cutter102with respect to the expander108at the flexible joint114(FIG. 1). The fitting314and the socket400form a ball and socket joint between the cutter102and the expander108. In another example, the socket400forms part of a hinge, universal joint and the like at the flexible joint114. The socket400cooperates with the fitting314to flexibly couple the cutter102with the expander108to traverse tight elbows and bends in piping. Optionally, the expander108includes the fitting314and the cutter includes the socket400. Referring again toFIG. 3, in yet another example, the cutter102rotates out of alignment with a longitudinal axis402(FIG. 4A) of the expander108at the flexible joint114(FIG. 1) during navigation of elbows and bends in piping. Optionally, the longitudinal axis308of the cutter102(FIG. 3) rotates out of alignment with the longitudinal axis402of the expander108during navigation of elbows and bends.

Additionally, the socket400is configured to transmit forces (e.g., pulling forces from the cable) to the cutter102(FIG. 3). The socket400engages against the fitting314(FIG. 3) and moves the cutter102along the pipe and thereby splits the pipe. In still another example, where the flexible joint114includes a hinge, universal joint and the like, the joint mechanism transmits forces from the expander108to the cutter102. Optionally, the expander108is constructed with a material capable of transmitting forces to the cutter102and the puller shoulder116(FIG. 2) and pry apart a split pipe (e.g., copper, lead, HDPE, PVC and the like). In one example, the expander108is constructed with, but not limited to, 1018 carbon steel and the like.

Moreover, the flexible coupling of the cutter102(FIG. 3) and the expander108(FIG. 4A) provides modularity to the pipe splitting assembly100. In one example, the cutter102is paired with one of a selection of expanders108(e.g., with different size perimeters, profiles, materials and the like) including similarly configured sockets400. Each expander108is thereby couplable with the cutter102to facilitate use of the cutter102with a variety of pipe diameters and materials. In another example, a new expander108is coupled with an existing serviceable cutter102without requiring a full replacement of the pipe splitting assembly100when an old expander108wears out. In still another example, the expander108is configured to couple with a variety of cutters102including fittings314configured to couple with the socket400. The cutters102include, but are not limited to, configurations with one or more blades, serrations, rolling cutting surfaces, tapered profiles for splitting pipe, different materials and the like. In yet another example, the expander108is configured to couple with a replacement cutter102to preclude replacement of the entire pipe splitting assembly100when the cutter wears out or fails. Optionally, the pipe splitting assembly100includes a kit having a variety of the cutters102and expanders108for differing pipe diameters, materials and the like. The kit includes instructions detailing which cutters102and expanders108to use in combination for a desired pipe size and material.

As described above, the cutter102flushly transitions to the expander108with the frusto-conical portion310, in one example. Optionally, the outer perimeter404of the expander108has a tapered profile and continues from the distal end110(adjacent to the cutter frusto-conical portion310) along the expander108toward the proximal end111. The tapered profile extends at an acute angle with respect to the longitudinal axis402of the expander, for instance, between less than 90 degrees and more than 0 degrees. Pipe split by the cutter102thereby moves over the cutter102and onto the expander108without snagging at the flexible joint114(FIG. 1). The tapered profile of the expander108bursts and pries the split pipe apart to make room for a replacement pipe and/or facilitate removal of the split pipe. In another option, at least a portion of the outer perimeter404of the expander108has a larger perimeter than the perimeter of the cutter102. For instance, the expander108includes ridges, crests, knurling and the like sized and shaped to pry apart pipe split by the cutter102. In yet another option, a portion of the expander outer perimeter404has a cross-sectional dimension (e.g., width, diameter and the like) larger than a cross-sectional dimension of the cutter102.

As shown inFIGS. 4A, B, the expander108includes an expander lumen406. The expander lumen406is sized and shaped to receive the cable106, shown inFIG. 1. The expander108is slidably coupled along the cable106during operation of the pipe splitting assembly100(FIG. 1). The cable106extends through the cutter102and the expander108and ensures that both pieces are coincident with the cable106during a splitting operation. The flexibility of the cable106permits the cutter102(FIG. 3) to rotate with respect to the longitudinal axis402of the expander108while ensuring the expander108follows the cutter102.

Referring now toFIG. 4B, the expander lumen406of the expander108is defined by an interior surface408. At least a portion of the interior surface408includes a tapered surface sized and shaped to engage with the collet200, as shown inFIG. 2. The interior surface408of the expander108engages against the collet200while the collet is pulled with the cable106(FIG. 2). The engagement of the interior surface408with the collet200forces the collet200to tightly grasp the cable106, as further described below.

The interior surface408further defines a shoulder joint410sized and shaped to couple with the puller shoulder116, shown inFIG. 2. The shoulder joint410transmits pulling forces to the puller shoulder116, bridge118, sleeve122and the replacement pipe126(FIG. 2). In one example, the shoulder joint410is sized and shaped to couple with the fitting204(FIG. 2) on the puller shoulder116. The shoulder joint410, in another example, includes, but is not limited to, threading, detents, mechanical locks and the like to securely the couple the puller shoulder116with the expander108. For instance, referring now toFIG. 2, the fitting204includes threading and the shoulder joint410(FIG. 4) includes complementary threading to retain the coupling between the puller shoulder116and the expander108.

FIG. 5is a perspective view showing the collet200. In one example, the collet200includes two or more jaws500sized and shaped to extend around the cable106(FIGS. 1 and 2). Optionally, the jaws500include a roughened interior surface502(e.g., serrations, knurling, projections and the like) configured to grasp the cable106and substantially prevent movement of the collet200along the cable106, as described below. In another option, the jaws500are substantially smooth and rely on friction between the jaws and the cable106to grasp the cable106and substantially prevent movement of the collet200relative to the cable106. The jaws500have a tapered profile that gradually increases from the distal end505to the proximal end506. The jaws500are retained around the cable106with a band206shown inFIG. 2. The band206is elastic, in another example, and provides sufficient force around the jaws500to hold them against the cable106. The band206is held within a groove504substantially adjacent to the proximal end506of the collet200, in still another example.

Referring again toFIG. 2, the collet200is positioned proximally relative to the expander108and the cutter102. When tension is applied to the cable106at one end of the pipe, (e.g., by a cable puller such as a capstan winch, another winch, by a vehicle and the like) the collet200is pulled into the expander108. Referring now toFIGS. 4B and 5, the jaws500of the collet200engage against the tapered interior surface408. The taper408presses against the jaws500and urges the jaws500into tight engagement with the cable106(FIG. 2). As the jaws500are urged against the cable106, the roughened surface502of each jaw500tightly grasps the cable106and substantially prevents relative movement of the collet200along the cable106. In another option, the jaws500are smooth and the friction between the jaws500and the cable106substantially prevents relative movement. The collet200thereby cooperates with the expander108to grasp the cable106and facilitate transmission of pulling forces to the pipe splitting assembly100(FIG. 1). Pulling forces in the cable106are transmitted through the collet200into the expander108and the cutter102. In one example, where the puller shoulder116is coupled with the expander108, pulling forces in the cable106are transmitted to the puller shoulder116. In another example, the tapered portion of the interior surface408has a complementary taper to the jaws500of the collet200. In yet another example, the interior surface408has a differing taper than that of the jaws500.

FIG. 6shows the puller shoulder116including the fitting204, puller base600and the bridge118. As described above, the fitting204is sized and shaped to couple with the shoulder joint410and thereby couple the puller shoulder116with the expander108(FIGS. 4A, B). In another example, the puller base600has a profile substantially similar to the profile of the expander108(FIGS. 1 and 2). The similar profile of the puller base600allows the puller shoulder116to move with the cutter102and expander108without performing any expanding function. The puller shoulder116pulls the replacement pipe121with the cutter102and the expander108, as shown inFIGS. 1 and 2. In yet another example, the pipe splitting assembly100does not include the puller shoulder116, and instead pulls the cable106through the split pipe. A replacement pipe is then pulled through on the cable106after the pipe splitting operation is completed. In still another example, the split pipe is removed and the remaining cable pulls the replacement pipe into place afterward, as further described below.

The bridge118of the puller shoulder116connects the puller shoulder116with the replacement pipe121and the puller sleeve122, shown inFIGS. 1 and 2. As described above, in one example, the bridge118includes threading120(FIG. 1). The threading120is configured to couple with the sleeve122and the replacement pipe121. In one example, the threading120is a tapping surface and cuts corresponding threading into the replacement pipe121, such as a plastic pipe (e.g., HDPE and the like). The threading cut into the replacement pipe121assists in grasping the replacement pipe121when it is pulled into place by the cable106. In another example, the threading in the replacement pipe121facilitates coupling of the replacement pipe121with other pipes121and pipe fittings, such as elbows.

Referring again toFIG. 6, in another example, the puller shoulder116includes a coupling ring602sized and shaped to couple with the puller sleeve122, for instance, the puller sleeve shown inFIG. 7, described below. The coupling ring602, in yet another example, includes threading configured to mate with corresponding threading on the sleeve122and thereby securely couple the puller sleeve122with the puller shoulder116. Optionally, the coupling ring602has features for coupling with the puller sleeve122including, but not limited to, mechanical fasteners, locks, welds, bolts and the like. In still another example, the puller sleeve122is integral to the puller shoulder116. The bridge118extending from the puller shoulder116includes apertures604. The apertures604cooperate with the puller sleeve122to retain the replacement pipe121along the puller shoulder116during a pulling operation, as described below. In yet another example, the bridge118includes features sized and shaped to grasp the replacement pipe121for pulling by the pipe splitting assembly100. For instance, the bridge118includes clamps, bolts, mechanical locks, deformable surfaces and the like configured to grasp the replacement pipe121and pull the pipe during a pipe splitting operation.

The puller sleeve122is shown inFIG. 7. The puller sleeve122includes a sleeve lumen700extending from a proximal end702to a distal end704. In one example, a first portion706of the sleeve lumen700is sized and shaped to couple with the coupling ring602of the puller shoulder116(FIG. 6). The first portion706, in another example, includes threading corresponding with threading in the coupling ring602. The puller sleeve122couples with the puller shoulder116by engaging the complementary threading. In yet another example, the threading of the puller sleeve122is coupled with threading120along the bridge118, as shown inFIGS. 1 and 2. The sleeve122is screwed onto the threading120and the threading120is also used to tap and grasp the replacement pipe121. Optionally, the puller sleeve122and the puller shoulder116are coupled with at least one of a variety of features, such as mechanical fasteners, locks, welds, bolts and the like. In another option, the puller sleeve122and puller shoulder116are integral.

The second portion708of the puller sleeve lumen700, in one example, has a slightly larger diameter than the first portion706. The replacement pipe121is received within the second portion708, and the bridge118extends inside the replacement pipe121, in another example. The replacement pipe121is thereby held between the puller sleeve122and bridge118. In the example of the bridge118shown inFIGS. 1 and 2, the puller sleeve122cooperates with the threading120on the bridge118to grasp the replacement pipe121and prevent the pipe121from slipping over the threading120. In the example of the bridge118shown inFIG. 6, the replacement pipe121is inserted between the puller sleeve122and the bridge118and the apertures of the bridge118and apertures710of the puller sleeve122are aligned. Optionally, the replacement pipe121includes pre-formed holes. Pins (e.g., bolts, screws, fasteners and the like) are inserted through the puller sleeve122, the replacement pipe121and the preformed holes of the bridge118to couple the replacement pipe121with the puller shoulder116. In another option, holes are formed in the replacement pipe121by driving the pins therethrough or drilling out holes.

Referring now toFIG. 8, in operation, the cable106is fed through a pipe (e.g., pipe800) that needs replacement and/or removal. The pipe splitting assembly100, including at least the expander108and the cutter102is coupled with the cable106. In one example, the cutter102is threaded over the cable106, and the expander108is threaded behind the cutter102. In another example, the collet200(FIG. 2) is coupled with the cable106behind the expander108. Tension is applied to the cable106, and the cable106and the collet200coupled therearound are drawn through at least a portion of the expander. Referring toFIG. 4B, the collet200is drawn into the expander lumen406and engages the interior surface408. The tapered portion of the interior surface408presses against the jaws500of the collet200(FIG. 5) and forces the jaws to tightly engage against the cable106. The roughened interior surfaces502of the jaws500grasp the cable106and substantially prevent movement of the collet200with respect to the cable106. The collet200thereby allows transmission of pulling forces from the cable106to the expander108. As shown inFIG. 8, the expander108is flexibly coupled with the cutter102at the flexible joint114. As described above, in one example, the flexible joint114is formed with the fitting314and the socket400to permit rotation of the cutter102with respect to the longitudinal axis402of the expander108(FIG. 4A). The pulling forces are transmitted to the cutter102from the expander108through the flexible joint114.

The pulling forces transmitted from the cable106to the cutter102force the cutter102into engagement with the interior surfaces of the pipe800, and the blades104press outwardly against the pipe interior surfaces to split the pipe800. In another example, the blades104have an acute angle with respect to the longitudinal axis308of the cutter102. The blades104cut the pipe from the pipe interior toward the exterior and thereby do not directly engage the end of the pipe800at an orthogonal angle. The tapered blades104substantially reduce the chance that the forces from the cutter102will move the pipe800in loose soil and the like instead of cutting the pipe800. Additionally, the tapered blades104require less pulling force to split the pipe than a blade directly engaged with the end of a pipe. In yet another example, the cutter102includes at least one of a single blade, plurality of blades, tapered splitting surface, serrations and the like. The cutter102, optionally splits the pipe800by repeated ramming engagement of a tapered splitting surface with the pipe800.

As shown inFIGS. 3 and 8, the cutter102includes at least two blades104. The blades104are shown on substantially opposite sides of the cutter102(e.g., about 180 degrees apart). In another example, the blades104are spaced a different interval, for instance between about 45 and 180 degrees apart. The two or more blades104split the pipe800at least twice thereby separating the pipe800into two or more pieces. In one example, the cable106extends fully through the pipe800and extends from a spool at a first end of the pipe800to a winch (e.g., a capstan winch) at the opposed end of the pipe800. The pipe splitting assembly100without the puller shoulder116, puller sleeve122and a replacement pipe121are pulled through the pipe800to split the pipe800into two or more pieces. The cable106remains therein and runs between both ends of the split pipe800. The split pipe800is then pulled (e.g., by attaching to a piece of heavy machinery such as a backhoe) to remove the split pipe800from the ground. Optionally, the pipe800is lead or HDPE and it is desirable to remove such pipe out of the ground, for instance because of environmental concerns. After removal, the cable106remains and the replacement pipe121is then pulled through on the cable106with an assembly similar in many respects to the puller shoulder116, bridge118and the puller sleeve122.

As described above, the pipe splitting assembly100includes a flexible joint114. The flexible joint114permits the cutter114to rotate relative to the expander108(e.g., with respect to the longitudinal axis402) when the cutter114navigates elbows and bends in the pipe800(e.g., a small diameter pipe). The flexibility of the cable106permits the expander108to follow the cutter114around corners while still operating to burst the split pipe800outwardly and thereby make room for the replacement pipe. Stresses between the cutter102and the expander108are thereby reduced in corners and elbows, and failure of the pipe splitting assembly100is substantially precluded. Frequent replacement of the cutter102and the expander108is thereby avoided.

FIG. 9shows one example of a method900for splitting an in-ground pipe, such as pipe800, shown inFIG. 8. One example, of a pipe splitting assembly used in the method900is shown inFIGS. 1-8as pipe splitting assembly100, and is referenced below. At902the pipe is split with a cutter102. At904, the pipe is burst with an expander108, and the expander108is flexibly coupled with the cutter102. In one example, the method900further includes pulling the cutter102and the expander108through the pipe with a flexible element, such as a cable106, coupled with the cutter and the expander. In another example, splitting the pipe with the at least one blade includes splitting the pipe with the at least one blade104extending at an acute angle with respect to a longitudinal axis308of the cutter102. The method900includes, in yet another example, splitting the pipe from an interior of the pipe toward an exterior of the pipe.

Several options for the method900follow. In one option, splitting the pipe includes splitting the pipe into separate pieces with the at least one blade and a second blade, for instance blades104. In another option, the method900includes pulling the separate pieces out of the ground. The flexible element (e.g., cable106) is left in the ground in place of the pipe, in yet another option. In another option, the method900includes pulling a second pipe121behind the expander108. In still another option, the method900further includes rotating the cutter102out of alignment with a longitudinal axis402of the expander108.

FIG. 10shows another example of a method1000for splitting a pipe. One example, of a pipe splitting assembly used in the method1000is shown inFIGS. 1-8as pipe splitting assembly100, and is referenced below. At1002, a cutter102is selected. For instance, a cutter102is selected for a particular pipe size, pipe material, number of desired cutting surfaces (e.g., blades104), material of the cutter102and the like. At1004, an expander108is selected. In one example, the expander108is selected based on, but not limited to, the material and/or configuration of the cutter102, the material of the pipe, the size of the pipe and the like. At1006, the cutter102is flexibly coupled with the expander. In another example, the cutter102is coupled with the expander108at the flexible joint114. In yet another example, the cutter102is rotated out of alignment with a longitudinal axis402of the expander108, for instance, to navigate corners and elbows. At1008, the pipe (e.g., pipe800) is split with the cutter102. At1010, the pipe is burst with the expander108.

Several options for the method1000follow. In one option, the method1000further includes uncoupling the cutter from the expander, and flexibly coupling a second expander with the cutter. In another option, splitting the pipe with the cutter102includes splitting the pipe into separate pieces with a first blade104and a second blade104. The method1000includes, in yet another option, pulling a second pipe121behind the expander108. Splitting the pipe (e.g., pipe800) with the cutter102includes splitting the pipe with at least one blade104extending at an acute angle with respect to a longitudinal axis308of the cutter. Optionally, the method100includes splitting the pipe from an interior of the pipe toward an exterior of the pipe.

CONCLUSION

The above described examples of pipe splitting assemblies and methods provide devices and methods usable to split a wide variety of pipe diameters including small piping with tight bends. The flexible coupling between the cutter and the expander allows the cutter to turn corners while the expander follows immediately behind the cutter. The flexible joint decreases stress in the cutter and the expander by allowing the cutter to navigate turns and elbows without having the expander rigidly coupled to the cutter. The flexible coupling thereby substantially prevents fracturing of the cutter or the expander when traversing elbows and bends, and consequently decreases cost and labor to replace either the cutter or expander.

Additionally, the flexible coupling makes the pipe splitting assembly modular and permits easy replacement of either one of the cutter and the expander without requiring replacement of the other component. Moreover, in another option, a variety of cutters with different geometries and cutting surfaces (e.g., tapered, multiple blades, blades at different angles, serrations, differing materials and the like) are matched with a desired expander. Further, a variety of expanders (e.g., of different sizes, different materials, geometries and the like) are matched with a desired cutter. Optionally, a selection of cutters and expanders are provided in a kit for use in a variety of pipe splitting applications, for instance, with different pipe sizes, materials and the like.

Moreover, the configuration of the cutter splits a pipe from the interior of the pipe toward the exterior. In one example, the cutter includes blades extending at an acute angle with respect to the longitudinal axis of the cutter. The blades taper and engage the interior of the pipe and do not directly engage the end of the pipe. The cutter thereby engages against the interior of the pipe first and presses outwardly while the cutter is pulled through the pipe. The blades, in another example, apply increasing pressure to the interior of the pipe and cut outwardly with movement of the cutter through the pipe. Because the cutter engages the interior of the pipe and does not directly engage an end of the pipe, the pipe remains stationary in the ground during the pipe splitting operation. Additionally, the tapered blades require less pulling force to split the pipe than a blade directly engaged with the end of a pipe.

In another example, the pipe splitting assembly pulls a replacement pipe immediately behind the cutter and expander in a single operation. An old pipe is split and burst and a new pipe is immediately pulled into place. In yet another example, the pipe splitting assembly is pulled without also pulling a replacement pipe. For instance, the cutter includes two or more blades that split the existing pipe into two or more pieces. The cutter is pulled through on a cable, and the cable remains in the location of the burst pipe. The pieces of the existing pipe are then pulled (e.g., with a backhoe, truck and the like) out of the ground, and the cable is left behind. A replacement pipe is then pulled through on the cable to replace the previously removed pipe. Removal of the existing pipe is optionally performed depending on the material of the pipe. For example, pipe materials including, but not limited to, lead, HDPE and the like are removed prior to positioning a replacement pipe.

Although selected advantages are described above, the list is not intended to be exhaustive. Further, the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. It should be noted that embodiments discussed in different portions of the description or referred to in different drawings can be combined to form additional embodiments of the present application. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.