Wire saw

A device for cutting a length of pipe includes a clamp portion for clamping around a length of pipe and a bow moveable with respect to the clamp portion that retains a loop of diamond embedded wire. The device further includes a feed for driving the bow with respect to the clamp portion and a detector for detecting bending of the wire and a control responsive to the detector for controlling feed rates. The device is made of modular parts and has synchronizing arms for clamping around a length of pipe. In one embodiment, the wheels are retained in enclosures with slots through which the cutting wire passes.

BACKGROUND OF THE INVENTION

Offshore oil rigs are supported by vertical pipes the lower ends of which are embedded in the ocean floor and the upper end of which extends above the surface. When an oil rig is abandoned, the supporting pipes must be sawed so as not to obstruct sea traffic or animal life.

Metal pipe used to support underwater structures come in diameters from the very smallest available up to at least 72 inches. A machine suitable for cutting such pipe must be resistant to deterioration caused by salt water and must be sized to accept and machine the particular diameter of pipe to be cut. Presently, it is the practice to provide a plurality of cutting machines in varying sizes to accommodate the different sizes of pipe. Accordingly, many different sizes of machines must be kept in inventory to deal with a complicated project involving the cutting of numerous sizes of submerged pipe.

One problem that that has plagued machines adapted to cut submerged pipe is that the machines typically include a plurality of contact pads that contact the surface of the pipe, and a pair of moveable arms that compress the pipe against the contact pads. The machine applies a loop of diamond embedded wire against the surface of the pipe and rotates the loop to cut the pipe. Where the pipe is to be cut thousands of feet below surface, the machine must grasp the pipe and undertake the cut without visual supervision. It has been found, however, that frequently the grasping arms do not force the length of pipe equally against all the retaining pads such that the device is somewhat skewed relative to the pipe. As a consequence of the skewed pipe, the machine may shake during the cutting process or realign itself against the pipe causing the cutting wire to snap.

The loop of wire that is the cutting element cannot be kept taut as it is applied against the surface but must be allowed to bend such that the longitudinal strength limitations of the wire are not exceeded. Currently it is the practice to provide a space consuming serpentine wire take-up assembly that will retain tension on the wire and allow the loop to be expanded as the cutting device is applied against the pipe. The serpentine wire take-up significantly enlarges the size of the machine and thereby makes it more cumbersome to handle.

It would be desirable to provide an improved machine that overcomes or reduces some of the forgoing problems. Specifically, it would be desirable to have a machine suitable for cutting a wide variety of sizes of pipe diameters such that a fewer number of machines are needed to cut all the sizes of submerged pipe that are available. It would also be desirable to provide a wire cutting machine that will more accurately grasp a length of pipe without requiring visual supervision and that does not require a serpentine wire take-up to prevent breakage of the wire.

The surrounding water in which the machine operates also causes resistance to movement and thereby reduces its efficiency. A major portion of the resistance generated occurs as a result of the rotation of the various wheels around which the loop of wire is moved. Even a wheel with a smooth surface will apply centrifugal forces to the surrounding water thereby reducing the efficiency of the machine.

One of the wheels is a drive wheel which applies force to the cutting wire causing it to rotate and cut the metal of a pipe. The drive wheel must therefore have a surface that contacts the cutting wire and has a sufficiently high coefficient of friction to apply the force to the wire needed to cut the metal of the pipe. The wheels of existing wire saws, excluding the drive wheels, are mounted on a shaft that extends between parallel plates, one on each side of the wheel such that an annular insert around the wheel cannot be replaced in the field.

Existing wire saws provide a strip of rubberized material that is bonded into an annular groove around the circumference of the wheel for engaging the surface of the wire and applying force to the wire causing it to rotate. The rubberized material within the groove however is worn away rapidly as the saw is used and therefore must be replaced often. Furthermore, since the rubberized material is in the form of a strip, the deterioration of the material occurs most rapidly where the ends of the strip meet each other at one location around the circumference of the wheel. It would be desirable to provide a resistive surface for a drive wheel that is more resistant to deterioration and does not require assembly that leaves a junction that connects two ends of a strip. It is also desirable that the material that forms the resistive surface be easily replaceable so that the machine can be serviced in the field.

To a lesser extent, the surfaces of the various guide wheels that also engage the cutting wire of a wire saw must have a degree of flexibility so as to minimize damage to the cutting wire as it moves around the guide wheel, and it is common therefore to provide a rubberized insert that fits within the groove of each guide wheel. The softer material in the groove of the guide wheel that engages the cutting wire must also be readily replaceable. It would be desirable to provide wheels for the wire saw that can receive annular inserts that can be replaced while the machine is in the field.

SUMMARY OF THE INVENTION

Briefly, the present invention is embodied in a device for cutting a length of pipe that includes a clamp portion for clamping around a length of pipe and a bow attached to the clamp portion for retaining a loop of diamond embedded wire. The bow is linearly moveable with respect to the clamp portion to apply the moving wire against the surface of a length of pipe clamped in the clamp portion. The device further includes a feed for driving the bow with respect to the clamp portion and thereby urging the length of wire across the diameter of the pipe to thereby cut the pipe.

In accordance with the invention, the clamp portion includes a plurality of pads for contacting against the surface of the pipe and at least one moveable arm for urging the pipe against the pads. A roller is provided at the distal end of the arm to allow the distal end of the arm to move along the surface of the pipe with a minimum of friction thereby allowing the arm to reach around the pipe and pull it against the pads without wedging into misalignment.

Preferably, the machine has two arms and the invention further provides for a synchronizing element between the first arm and the second arm for coordinating movement of the two arms such that neither arm will move faster than the other.

In another embodiment of the invention, a wire take-up is provided that allows enough slack within the length of wire to permit sufficient bending of the wire as it cuts to prevent wire snapping. The device further includes a detector, for detecting the degree of bending of the wire and a control responsive to the detector for controlling the feed rate in response to the bending of the wire.

A plurality of wheels on the bow engage the diamond embedded wire and retain the wire as it moves in a circular path to cut the length of pipe. One of the wheels is a drive wheel having an annular groove in its outer surface into which the cutting wire is received. The wheel includes a first annular side member and an opposing second annular side member each of which has circular outer circumferences and attach to opposite sides of a circular central body. The outer circumferences of the side members are spaced from each other leaving a groove between them for receiving the diamond embedded cutting wire. The first side member is retained to the remaining portions of the wheel by means of a plurality of removable fasteners and an annular composite insert, preferably made of urethane, is fitted into the groove formed between the spaced apart outer circumferences of the two side members. To replace a composite insert that increases the friction between the wire and the wheel, a plurality of fasteners are removed thereby permitting the first side member to be removed while the second side member remains attached to the machine. This allows easy replacement of the annular composite insert. Since the insert extends around three hundred and sixty degrees, the insert does not have a union of two ends of a strip of material wrapped around the groove of a wheel as is the case with the prior art and therefore has a longer useful life.

In another embodiment of the invention, each of the various wheels that drive the cutting wire is enclosed in stationary housings. As a result, the rotating surfaces of the wheel do not contact the surrounding water thereby minimizing the centrifugal forces applied to the surrounding water.

In yet another embodiment of the invention, the machine is modular in construction, such that the position of the clamping arms are adjustable with respect to the frame so as to be made suitable for grasping a wide range of sizes of pipe.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring toFIGS. 1 through 4, a wire cutting machine10for cutting a length of pipe12includes a frame14having a plurality of contact pads15,16,17,18thereon for positioning the frame14against the surface of the pipe12. The machine10is suspended at the desired elevation and orientation by a plurality of wires, not shown, that extend downward from the surface with each wire attaching to a connector11,13,19on the machine10.

Mounted with respect to the frame14are first and second arm assemblies each of which includes an upper arm20,22attached to the frame14and a lower arm21,23movable with respect to the associated upper arms20,22for reaching around the outer circumference of the pipe12and retain the frame14firmly against the pads15-18. The machine10further includes a bow24having a central portion26and two generally arched arms28,30having guide wheels32,34at the distal ends thereof. Positioned near the central portion26is a drive wheel36which is drivingly rotated by an appropriate motor38. Mounted on the opposite side of the central portion26is a take-up wheel40, and wrapped around the four wheels32,34,36,40is a loop of diamond embedded wire42of the type commonly known in the art. To cut across the length of pipe12, the bow24is retained to the frame14by a plurality of elongate vertically oriented parallel tracks43,44,45attached on the frame14with each track43,44,45receiving a slideable track follower46,47,48mounted on the bow24so as to be longitudinally moveable in a plane perpendicular to the length of the pipe12. The bow24is driven with respect to the frame14by a threaded feed shaft49rotated by a motor51to thereby force the portion of the wire42that extends between wheels32,34at the ends of the arms28,30through the pipe12to sever the pipe12.

As best shown inFIGS. 2,4, and6, the central portion of the frame14is formed by a pair of identically shaped spaced apart plates50,52, each of which has a generally convex inner curve54, the lower ends of which extend partially around the circumference of the length of pipe12to be cut. Opposite the inner curved side54and spaced several inches therefrom each plate50,52has an outer concave curved side55and at each of the ends of the inner and outer sides54,55are parallel outer edges56,58. The plates50,52are maintained in parallel spaced relationship by a plurality of equal length spacer rods60-60retained by screws, not identified. Attached to the inner U-shaped sides54of both plates50,52are a pair of transverse mounting plates62,64the outer surfaces of which retain the pads15,16,17,18. An outer bracket66(best seen inFIGS. 1 and 5) extends between the outer surface of plate52and one end of the mounting plates62,64and has mounted thereon connectors67-67for retaining hydraulic lines, not shown, for directing hydraulic fluid to the motor38and to other powered components of the machine10. Each of the plates50,52also includes two angularly oriented linearly arranged series of equally spaced transverse holes68-68and70-70. Each series of holes68-68,70-70has one end oriented near the center of the exterior curved side55and the other end near the neck formed between the interior curved side54and one of the outer edges56,58.

Referring toFIGS. 4 and 7, removably fitted between the plates50,52near each of the outer edges56,58are upper arms20,22and moveable lower arms21,23, one set of which20,21is depicted inFIG. 7and is representative of both. Each of the upper arms20,22is formed by a pair of side members72,74which are retained in parallel spaced relationship by a plurality of spacer rods76-76with the distance between the outer edges of the side members72,74being a little smaller than the distance between the inner surfaces of frame plates50,52so as to fit therebetween. Each side member72,74is generally elongate and has a first end78,80, and a second end82,84. Positioned between the first ends78,80and retained by bushings86,88is one end of a hydraulic cylinder90. Midway along the length, each side member72,74has a pair of spaced apart holes120,121and122,123therein with the distance between each pair of holes120,121and122,123being equal to the distance between any two sets of adjacent holes68-68and70-70in the frame members50,52. Positioned between the second ends82,84of the side members72,74and mounted on a pivot pin92is the moveable lower arm21formed by parallel lower arm members94,96.

The lower arm members94,96are elongate in shape having first ends98,100joined together by a pin that extends through a pivot eye102at the distal end of a piston rod104that is moveable by the cylinder90. A pivot pin92retains the lower arm21to the upper arm20and extends through holes106,108that are centrally located in each of the lower arm members94,96such that extension of the piston rod104causes the second ends110,112of the lower arm members94,96to be urged towards the surface of a length of pipe fitted between the lower necks at the outer edges56,58of the frame plates50,52. A roller114is rotatably retained by a pin115between the second ends110,112such that the distal end of the lower arm members94,96will roll against the surface of a pipe12as the arm members adjust around the surface thereof.

Referring toFIGS. 2,7, and14, an operator controls the machine10from a control panel, not shown, on the surface, and the control panel consists of control handles, not shown, for manually operable valves that direct hydraulic fluid from a source such as a pump240to the various motors38,51and the cylinders90. The operator's controls include a manually operable control valve93and a manually operable reversing valve91in line117to the cylinders90to operate the arms21,23. One aspect of the present invention is that a fluid flow divider116is provided after the operator's control valves91,93in the hydraulic line117, which equally divides the flow of hydraulic fluid through the lines118,119that ultimately lead to the two cylinders90. By equally dividing the flow of fluid to the two cylinders90, the lower arms21,23move in unison as they wrap around a length of pipe12. Each of the cylinders90also has an operator controlled reversing valve91to enable an operator to release the arms21,23from around a length of pipe12. By moving the lower arms21,23in unison the arms cooperate with each other as they move around a length of pipe and drawing it uniformly against the pads15-18, thereby preventing the pipe from being skewed as it is grasped. Also, the rollers114at the second ends110,112of each of the lower arms21,23enable the lower arms to reposition with respect to the pipe with a minimum of friction.

Referring toFIGS. 1,4,5,6, and8, to retain each of the upper arms20,22at its desired location along the outer edges56,58of the frame plates50,52a pair of pin forks124,125are provided, one pin fork to retain each upper arm20,22. Each pin fork124,125has a central body126with parallel transverse holes, unnumbered, near the ends thereof and a rod127,128in each of the holes so as to be retained in parallel spaced relationship. To structure the frame14of the machine10to grasp the largest size pipe, as shown inFIG. 1, the rods127,128of the pin forks124,125are extended through the spaced holes68-68and70-70that are positioned nearest the necks of the outer edges56,58and through aligned complementary spaced holes120,121, and122,123of the upper arms20,22. To reconfigure the machine10to cut a much smaller diameter length of pipe as shown inFIG. 5, the holes120,121and122,123of the upper arms are aligned with the pair of holes68-68and70-70nearest the exterior curves55and the rods127,128of the pins124,125inserted therein. Accordingly, the machine10can be reconfigured to cut a wide variety of sizes of pipe12by merely repositioning the upper arms20,22to allow the lower arms21,23to grasp the desired diameter pipe and locking the upper arms20,23in the desired orientation.

Referring toFIGS. 4 and 9, the central portion26of the bow24is formed by spaced apart parallel plates129,130, with each plate129,130having generally arcuate outer and inner edges131,132and first and second angled sides133,134. A pair of aligned ears135,136are provided along the first sides133and a second pair of aligned ears137,138are provided along the second sides134. A pair of aligned holes, unnumbered, through the first pair of ears135,136receive a pivot pin127for pivotally retaining a mounting145for the drive roller36and the motor38.

The mounting145includes a pair of plates139,140each of which generally defines a triangle with the corners141,142,143aligned with each other the drive motor38and drive roller36are mounted on a shaft144extending through holes in a first pair of aligned corners141and the pivot pin127extends through holes in a second pair of corners142. One end of a pretensioning member148is pivotally attached by another pin146through the aligned holes, unnumbered, in the third corners143for adjusting the orientation of the mounting138around pin127.

Referring toFIGS. 9 and 10, the pretensioning member148includes a tubular body150that slideably receives one end of a threaded shaft152. The opposite end of the threaded shaft152has an eye154connected thereto for pivotally receiving the pin146on the mounting145. A nut155is threaded on the shaft152between the eye154and the tubular body150. The second end of the tubular body150is attached to a mounting member156which is retained between parallel plates163,164, at the distal end of the first arm28. The mounting member156has parallel spaced apart outer surfaces157,158with threaded holes therein, one of which159is visible inFIG. 10. Each of the plates163,164, which also retain wheel32to the first arm28, has an ear162with a hole therein. A mounting screw160,161extends through the hole in each ear162and into the threaded hole159in each surface157,158to retain the second end of the tubular body150. Accordingly, rotation of the nut155will urge the threaded shaft152longitudinally outward of the tubular body150and thereby apply tension to the diamond cutting wire42that extends around the wheels32,34,36,42. A plurality of knobs165-165positioned on posts, unnumbered, around the circumference of the nut155enable the nut to be manually rotated to apply the desired tension to the wire42.

Referring toFIGS. 4,9,10and11, extending through aligned holes in the second pair of ears137,138at the opposite side of the central portion26is a pin170which rotatably receives a second retainer172for retaining the take-up roller40. The second retainer172consists of a pair of parallel plates174,176, each of which generally bears the shape of a boomerang with the take-up roller40mounted on a shaft178positioned at the bend near the center of the boomerangs. The pin170extends through a pair of aligned holes at one end of the plates174,176, for pivotally mounting the retainer172and the take-up roller40to the bow24. The opposite ends of the boomerang-shaped plates174,176have a second pair of aligned holes, unnumbered, which receive another pin180for rotatably receiving one end of a spring loaded wire tensioner184.

Referring toFIGS. 9,11and12, the wire tensioner184includes an elongate shaft186is inserted into the end of an elongate retainer199having the eye182for receiving the pin180. The opposite end of the shaft186is slideably received in a transverse hole187that extends longitudinally through a second retainer188. The distal end of the second retainer188has parallel spaced apart outer surfaces189,190each having a threaded hole therein for receiving screws191,192. The screws191,192also extend through aligned holes in a pair of ears193,194in parallel plates195,196positioned at the outer end of the second arm30to retain the second end of the shaft186thereto. Extending around the circumference of the shaft186is a compression spring198that is compressed between the retainer199near the eye182and an annular surface200on the retainer188by the tension in the wire42. The spring198is therefore compressed as the shaft186is urged deeper into the transverse hole187. Accordingly, rotating the nut155on the pretensioning member148increases the tension in the wire42and compresses the spring198causing the distal end of the shaft186to move further into the hole187in the retainer188.

As best shown inFIGS. 11,12and14, mounted parallel to the distal end of the shaft186is a hydraulic cylinder202. Within the cylinder202is a piston,203, having a shaft204at the end of which is a connector member206. The connector member206joins the shaft204to the free end of shaft186that extends out through the second retainer188. The piston203therefore moves with the shaft186as tension in the wire42changes and as the bending of the wire42changes. The cylinder202is connected by a pair of hydraulic lines, jointly identified by indicia number208, with the hydraulics configured to move the piston and associated piston shaft252of cylinder250in unison with the movement of piston203and shaft204of cylinder202.

Referring toFIGS. 14 and 16, the rod252has an enlarged end254sized to engage the prongs of a fork256at the end of a lever arm258when the rod252is drawn into the cylinder250and approaches the end of its travel. Compression of the lever arm258activates a hydraulic shut off valve260that stops the flow of hydraulic fluid to motor51that turns the feed screw49. The piston rod252therefore moves responsive to changes in the tension in wire42, and the enlarged head254is adapted to engage the fork256and close the shut off valve260when the wire42bends more than desired, as is further described below.

Referring toFIGS. 1,4,13and13A, the feed screw49has one end rotatably mounted in a plate212retained at the upper end of the center track44of the frame14and the opposite end rotatably mounted in a mounting block219adjacent the lower end of the center track44. A feed nut216threadedly receives the feed screw49and is secured by bolts, not shown, to plate52of the center portion26of the bow24such that rotation of the feed screw49causes longitudinal movement of the bow24along the tracks43,44,45.

The hydraulic motor51is also mounted on the upper plate212and is drivingly connected through first and second sprockets220,222and a chain224to the feed screw49. The second sprocket222engages the feed screw49through an overload release clutch in the form of a pin226that extends transversely through the end of the shaft of motor51with the outer ends of the pin226engaging radially outwardly extending grooves228,230in the second sprocket222. The pin226is forced into the grooves228,230by means of a plurality of compressible washers232-232. The sprockets220,222and washers232-232are retained in assembled relationship by an outer end plate235. Accordingly, if the load on the feed screw49becomes excessive, the pin226will disengage from the grooves228,230and allow the second sprocket222to rotate while the feed screw49remains stationary.

Referring toFIG. 14, hydraulic fluid flows in only one direction; however it should be appreciated that for every outwardly directed flow line a corresponding return line is also provided. The lines are not shown in pairs, but rather a single line is provided to show the hydraulic connection that includes flow lines in both directions. A control valve241, manually operable from the surface, directs fluid from the pump240through line242through the shut off valve260and then to the motor51. Shutoff valve260is operated by cylinder250and cylinder202, with cylinder202controlled by the spring loaded tensioner184. Tension in the wire42, that exceeds a preset threshold, as detected by the spring loaded tensioner184, will therefore terminate the flow of hydraulic fluid to the motor51causing it to stop. A reversing valve243, which is also manually operable from the surface, is positioned along line242and before the shut off valve260and enables an operator to reverse the direction of the motor51to withdraw the bow24after a cut has been made. The motor38that drives the cutting wire42is controlled by a separate valve245in a dedicated supply line246and valve245is manually operable from the surface.

As shown inFIG. 9, the drive wheel36applies force from the motor38to the wire42to rotate it around the various guide wheels32,34,40. In order to apply sufficient force to the wire42to cut the steel pipe there must be a sufficiently high coefficient of friction between the contact surface of the drive wheel36and the cutting wire42. To provide such a high coefficient of friction, existing wire cutting machines have an elongate strip of rubber inserted into the annular groove in the outer circumference of the drive wheel. The rubber strip is compressible and provides the desired friction to drive the wire42. The rubber from which such strips are formed is not sufficient elastic to be configured as a three hundred and sixty degree loop that can be expanded and snapped over the circumference of the drive wheel. Instead, the contact material is formed by cutting an elongate ribbon of material to the desired length and wrapping the length of ribbon within the groove of the drive wheel with the ends of the ribbon positioned in close proximity to each other. Since the material of which the elongate ribbon is formed has a relatively high degree of flexibility, it is subject to wear and must frequently be replaced. Existing ribbons of contact material are replaced by first ripping out the worn ribbon after which a new length of ribbon is cut to the desired length and bonded into place. One problem with such elongate ribbons of friction material is that the material deteriorates most rapidly at the junction of the two ends of the length of ribbon.

Referring toFIGS. 17,18, and22, the drive wheel36of the present invention has a disc-shaped central body270, preferably made of aluminum, with a circular outer circumference and a circular central opening274. A plurality of holes276-276are equally spaced around the central opening274for receiving screws, not shown, for attaching the drive wheel36to the shaft144(visible inFIG. 9) of the drive motor38to thereby apply rotational force to the drive wheel36. Positioned on opposite sides of the central body270are first and second annular outer rings278,280retained to the circumference of the central body270by removable screws288-288and290-290respectively. Fitted within the central openings of the outer rings278-280and against opposite surfaces of the central body270are plastic annular spacers284,286. The outer circumference of the rings278,280is larger than the outer circumference of the central body270and each of the rings278,280has an annular groove283,285that is directed toward the other forming opposing outer lips287,289. Accordingly, when the parts are assembled together, the outer lips of the two rings278,280are spaced apart and the grooves283,285combine to form a single annular groove around the outer circumference of the assembled parts, a portion of the floor of which is the outer circumference of the central body270. An annular urethane insert282has an inner diameter sized to fit into the groove formed by the outer diameter of the central body270and the grooves283,285. In the preferred embodiment, the outer circumference of the insert282has an annular groove292therein into which the diamond cutting wire42is received. The annular urethane insert282has sufficient resilience to provide the high coefficient of friction needed to apply adequate force to the diamond cutting wire42to cut into the steel of the pipe12.

As can be seen inFIG. 18, when the parts of the drive wheel36are assembled together, the side surfaces of the drive wheel36are substantially planar, interrupted only by various transverse holes that are occupied by the heads of threaded screws and a relatively small annular ridge294that defines the inner circumference of the outer rings278,280.

The annular insert282can also be easily replaced by first removing the retaining screws288-288of one of the rings278. Once ring278has been removed, the worn insert282can be removed and the replacement installed without stretching the insert282. After the insert282has been replaced, the ring278is reassembled and the retaining screws288-288inserted to retain wheel36together. In the preferred embodiment, the central body270of the wheel36and the second ring280remain mounted on the shaft144while the outer ring278is removed and the inset282is replaced, such that the insert282can be replaced in the field without disassembling the bow24.

Referring toFIGS. 19 and 20, the guide wheels32,34,40are formed in a fashion similar to the drive wheel36and guide wheel32is representative of all three guide wheels32,34,40. The guide wheel32includes an annular central body310made of aluminum or other suitable material. Secured to one side of the central body310by a first plurality of screws333-333is a first end plate338and secured to the opposite side of the central body310by a second plurality of screws335-335is a second end plate340, each of which has a central opening sized to receive one end of an annular hub316. Extending through the hub316is a non-rotatable shaft322upon which the hub316is supported by bearings318,320. The parts are maintained in assembled relationship on the axle322by a plurality of retainers324,326,328and by outer retainer rings330,332to thereby permit rotation of the wheel32about the axle322. The inner cavity of the central body310is filled with a lightweight annular plastic filler312.

Fitted around the outer circumference of the second central body310is another annular urethane replaceable insert334having an annular groove336around the outer circumference thereof. The replaceable urethane inserts334useable with the guide wheels32,34,40are made of a harder urethane compound than the material of which the insert282of drive wheel36is made and therefore has a longer useable life. Like the drive wheel36, the insert282around each of the remaining wheels32,34can be replaced by first removing the screws333-333and one end plate338while the remaining portions of the wheel32remains on the bow24.

Referring toFIGS. 9,21,22, and23, in another embodiment of the invention, each of the various wheels32,34,36,40that retain the cutting wire42are enclosed in a non-rotating enclosure with each enclosure having an arcuate slot therein through which the wire42passes to wrap around the wheel therein. As shown inFIG. 21, wheel32is within enclosure342, wheel34is within enclosure344, wheel36is within enclosure346, and wheel40is within enclosure350.

As shown inFIG. 22, in which wheel36and enclosure346are representative of all, enclosure346is formed as a clam shell with a first half352and an opposing mirror image second half354. As can be seen, the first and second halves352,354have planar portions356,357that extend parallel to the adjacent surfaces of the body of the wheel36and an inwardly directed outer lip358,359that wraps around the outer circumference of the wheel36. The outer lips358,359meet each other for a portion of the circumference of the enclosure but leave a gap forming a slot360that extends around the portion of the wheel36that receives the wire42. The first half352is retained by screws362to plate139and the second half354is retained by screws364to plate140where plates139and140form retainer145.

When the first and second halves352,354are assembled to form the enclosure346, the enclosure346will completely surround the rotating wheel36thereby preventing the rotating wheel36from applying rotational force to the surrounding water. The diamond cutting wire42extends through the slot360to reach the groove292in the insert282.

Referring generally to all the figures, to operate the wire cutting machine10, the pretensioning member148is adjusted to apply sufficient tension to the diamond embedded wire42to incrementally compress the spring198of the spring loaded tensioner184. The cylinders90are operated to wrap the lower arms21,23around a length of pipe12to retain it against the pads15-18. Power is applied from the source240through the hydraulic lines242to operate the motor38to rotate the drive wheel36to thereby drive the diamond embedded wire42. Simultaneously, hydraulic fluid is supplied through line244to the hydraulic motor51to operate the feed screw49causing the bow24to move along the tracks43,44,45until the portion of the wire42extending between the wheels32,34engages the surface of the pipe12. As the feed screw49continues to rotate, the bow24is moved further along the tracks43,44,45and the wire42begins cutting into the surface of the pipe12. Further movement of the bow24along the tracks43,44,45causes the wire42to bend around the pipe12as it continues to cut. As the wire bends, the spring198of the spring loaded tensioner184is further compressed until movement of the shaft186causes the piston rod head254to engage the fork256. Further bending of the wire42will then cause the cylinder250to operate the shut-off valve260thereby terminating the flow of hydraulic fluid to the motor51and stopping the feed screw49. The motor38that drives the diamond wire42will continue to operate and the wire42will continue to cut the pipe12until it cuts sufficiently through the pipe12to reduce the bending in the wire between the wheels32and34. As the bend of the wire between the wheels32and34is reduced, the spring198will take-up the wire42until movement of the shaft186causes cylinder250to reopen the shut-off valve260allowing hydraulic fluid to again flow to the motor51. As the motor51begins operating, it will again rotate the feed screw49and advance the bow24further along the tracks43,44,45and causing the length of wire between wheels32and34to again bend further around the pipe12as the wire continues to cut the pipe. In this fashion, the rate at which the feed screw49drives the bow24and advances the wheels32,34is dependent upon the bending of the wire42between the wheels32and34. The feed screw49and motor51stop movement of the bow24when the bending becomes excessive and advance the bow24as the spring198takes up excess wire42. By linking the drive rate of the feed screw49to the bending of the wire42it is not necessary to provide a serpentine-type wire take-up to prevent the application of excessive forces to the wire42.

All the wheels32,34,36,40that retain the diamond cutting wire42rotate on parallel axes and are positioned to retain the wire42in one plane. This is not possible where a serpentine-type take-up is needed to prevent excess forces within the wire. One benefit of maintaining the wire42within a single plane is that the wire42is not twisted as it operates. Twisting of the wire generates forces perpendicular to the direction of motion of the wire and such forces must be accommodated to prevent mechanical failure of the wire.

Referring toFIGS. 9,17,21, and22, to replace the urethane insert282of the drive wheel36, an operator will remove plate139to obtain access to the outer ring278. The retaining screws288-288and the outer ring278are then removed, after which the worn annular insert282is replaced with a new one. Thereafter, the parts and retaining screws are reassembled without removing the drive wheel36from the shaft144. Accordingly, the annular insert282is easily replaced by an operator in the field. Furthermore, since the insert282is continuous through three hundred and sixty degrees, it does not have a pair of adjoining ends which are subject to deterioration requiring the premature replacement of the contact material needed to drive the cutting wire42.

The wire cutting machine10is preferably made of aluminum or stainless steel with the parts assembled together by bolts and the like so as to avoid welding or other processes which are subject to deterioration as a result of being submerged in salt water. By providing that the machine10is made in modular parts that include the frame14, the bow24, and the arm assemblies20,21and22,23, the parts can be replaced for parts of different sizes as needed, and the parts reassembled in different orientations to fit different sizes of pipe12. The modular parts also facilitate the transportation of the machine to a work site where it can be easily assembly.

Referring toFIG. 15, another advantage of modular parts is that the machine can be modified to perform other functions. For example, a machine owner may purchase optional parts such as a guillotine saw370that has track followers, not shown, positioned to engage the tracks43,44,45on the frame14. The owner might also purchase a drill assembly372with similarly configured track followers such that the frame14and arms20,22can receive the bow24mounted wire saw, the guillotine saw370or the drill372. The modular parts therefore permit an operator to assemble the machine to perform any of a number of functions.

While many specific aspects of the present invention have been described, it will be appreciated that many more modifications and variations may be made without departing from the spirit and scope of the invention. It is therefore the intent of the appended claims to cover all such modifications and variations which fall within the spirit and scope of the invention.