Fusion Bonded Epoxy Removal Tool

Abstract

A tool for removing fusion bonded epoxy coating from the surface of a pipe has an elongate rotatable shaft suitable for being received in a rotating tool holder of a machine. Extending radially outward of the distal end of the shaft are a plurality of fingers, the outer ends of which are spaced apart. Each of the fingers is made of a spring metal, and at the distal end of each finger is an abrasive pad having diamond particles embedded in soft metal. Spring force is independently applied by each spring finger to its associated abrasive pad.

Description

BACKGROUND OF THE INVENTION

With the advent of offshore drilling and the transportation of liquids such as gas and oil through underwater pipes robotically operated machines are needed to repair pipes that extend through deep waters. Such pipes are electrically connected along their length. They also have a coating of fusion bonded epoxy on their outer surface to protect the metal of the pipe from corrosion caused by the chemicals in the ocean. To repair a submerged pipe, the pipe must first be cut in two locations to remove a defective portion, after which the disconnected ends of the undamaged portions must be prepared to receive a repaired length of pipe. One of the steps needed to prepare the end of a length of pipe is to remove a portion of the fusion bonded epoxy coating from the outer end of the pipe in order that a good electrical connection may be made through the repair length. Also, the manufacturers of the couplings that attach the repair length to the existing pipe do not guarantee a tight seal unless the fusion bonded epoxy is removed from the repair area.

Currently, the fusion bonded epoxy coating for underwater pipes is removed by providing a rotating drum, the outer surface of which has embedded therein hard particles of tungsten carbide. The surface of the drum is applied to the surface of the pipe and the drum rotated causing the tungsten carbide particles to remove the fusion bonded epoxy.

It has been found that it is difficult to apply the desired force of the drum against the outer surface of a pipe having an epoxy surface because of the weight of the drum itself. Where the drum is to remove epoxy from the upper surface of the pipe, the weight of the drum may exceed the force desired to be applied to the surface and therefore the machine rotating the drum must compensate for the weight being applied. Conversely, where the drum is rotated against the lower surface of a pipe, the machine that rotates the drum must apply a force greater than the drum weight against the lower surface of the pipe to overcome the weight of the drum and provide sufficient force to remove the epoxy surface. Similar problems exist where the drum is applied against a horizontal portion of the pipe. Furthermore, it has been found that the tungsten carbide particles that are embedded in the drum tend to cause excess damage to the metal of which the pipe is made. Accordingly, there is a need for an improved tool for removing an epoxy bonded surface from a pipe, especially where the pipe is submerged.

BRIEF DESCRIPTION OF THE INVENTION

Briefly, the present invention is embodied in a tool having an elongate rotatable shaft suitable for being received in a rotating tool holder of a machine. Extending radially outward of the distal end of the shaft are a plurality of fingers, the outer ends of which are spaced apart.

In accordance with the invention, one of the fingers is made of a spring metal, and at the outer end of the finger is an abrasive pad having a plurality of diamond particles embedded therein.

In the preferred embodiment, each of the fingers is made of a spring metal, and at the distal end of each finger is an abrasive pad having diamond particles embedded in soft metal. Accordingly, a spring force is independently applied by each spring finger to its associated abrasive pad.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention will be had after a reading of the following detailed description taken in conjunction with the drawings wherein:

FIG. 1 is a side elevational view of a tool in accordance with the present invention;

FIG. 2 is a top elevational view of the tool shown in FIG. 1;

FIG. 3 is a bottom view of the tool shown in FIG. 1;

FIG. 4 is a cross-sectional view taken through line 4-4 of FIG. 2; and

FIG. 5 is an exploded view of the tool shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 through 5, a tool in accordance with the present invention, a tool 10 is rotatably symmetric about an elongate shaft 12 having a rearward end 14 adapted for insertion into the retainer of a rotatable machine, not shown, a longitudinal axis 15, and a threaded outer end 16 for threadedly retaining a working end 18. For the purposes of this discussion the working end 18 of the tool 10 shall be considered the forward end of the tool 10, and elements described herein that are directed axially toward the working end 18 shall be considered the forward end thereof and elements that are directed axially toward end 14 of shaft 12 shall be considered the rearward end thereof.

The working end 18 is generally disc shaped in appearance and includes a centrally located hub 20 having a planar forward surface 22 and a parallel planar rearward surface 24. Extending rearwardly of the rearward surface 24 is a cylindrical projection 26 having opposing flats 28, 29. Extending axially through the body of the hub 20 and the projection 26 is a threaded cylindrical bore 30 sized to threadedly receive the forward end 16 of the shaft 12. A hex jam nut 32 is also threaded on the forward end 16 of the shaft 12 before the hub 20 for locking the hub 20 to rotate with the shaft 12. Extending around the circumference of the hub 20 are planetary parallel threaded bores 34 the centers of which define a circle that is concentric with the threaded bore 30. In the preferred embodiment, the forward end of the shaft 12 does not extend beyond the forward surface 22 of the hub 20.

Positioned adjacent the forward surface 22 of the hub 20 are first and second identically shaped star wheels 36, 38, each of which has a plurality of elongate fingers 40. In the embodiment depicted, each star wheel 36, 38 has nine identical fingers 40, however it should be appreciated that the working end 18 of the tool can be made with more fingers or fewer fingers without departing from the spirit and scope of the invention. Each star wheel 36, 38 is made of a spring steel and preferably has a thickness of about one-sixteenth of an inch. Each of the star wheels 36, 38 also has a centrally located opening 42 and positioned around the central opening 42 are a plurality of spaced apart planetary holes 44 that are equal in number to the threaded bores 34 in the hub 20. The planetary holes 44 define a circle coaxial with the central opening 42 of the star wheel and equal to the diameter of the circle defined by the planetary holes 34 of the hub 20. The star wheels 36, 38 are retained to the forward surface 22 of the hub 20 by a plurality of screws 46-46 sized to be slideably received in the holes 44 of the star wheels 36, 38 and threadedly received in the bores 34 of the hub 20. With the star wheels 36, 38 secured to the forward end of the hub 20, the fingers 40 of both star wheels 36, 38 align with one another and thereby double the effective spring force provided to each of the star wheels independently.

At the outer end of each finger 40 of the aligned star wheels 36, 38 are a pair of transverse holes 48, 50. Each of the fingers 40 has attached at its outer end a generally rectangular mounting plate 52 having threaded holes 54 therein sized and positioned to receive screws 58-58. The screws 58-58 are fitted through the holes 48, 50 at the distal end of each of the fingers 40 and into the threaded holes 54 of the mounting plates 52 for retaining the mounting plate 52 to the forward surface of each of the fingers 40. The mounting plates 52 therefore formed in a planetary ring on the forward surface of star wheel 38 with each mounting plate at the distal end of each of the fingers 40.

In accordance with the present invention, each mounting plate 52 has attached to the forward surface thereof an arcuate shaped diamond cutting segment 60. The diamond cutting segments 60 are preferably made of a soft metal, such as silver or an alloy thereof with particles of diamond material 62 embedded into the soft metal. Each segment 60 is soldered or otherwise secured to the forward surface of one of the mounting plates 52. The forward surface of each of the segments 60 can therefore be applied to the surface of a pipe to remove the fusion bonded epoxy on the outer surface thereof.

A removal tool 10 in accordance with the present invention that has a plurality of independently springed fingers 40 and a diamond cutting segment at the distal end of each finger which will independently move across the portion of the surface of a coated pipe. The diamond particles in the various segments 60 provide an abrasive surface suitable for removing the fusion bonded epoxy. After each segment has removed a portion of the epoxy layer, the spacing between adjacent fingers permits water to circulate around the individual segments 60 and wash accumulated debris from the surface of the segment before rotation again brings the segment 60 in contact with the surface of the pipe. Also, the provision of independently adjustable fingers 40 allows each finger to apply the force desired to remove the epoxy surface from a pipe. Furthermore, the spacings between the fingers allow a remote camera mounted on the machine retaining the tool 10 to view the underlying pipe between the passage of the successive fingers, such that an operator can view the operation of the tool without removing the tool from the work site. It has also been found that where the segments employ relatively small particles of diamond, the hard cutting material does not unduly damage the outer surface of the pipe as was the case with a removal tool that employed tungsten carbide inserts.

While the present invention has been described with respect to a single embodiment, it will be appreciated that many modifications and variations can 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 that fall within the spirit and scope of the invention.

Claims

1. A tool comprising a rotatable shaft,a plurality of fingers extending radially outward of said shaft,one of said fingers made of a spring metal,said one of said fingers having an outer end, an abrasive pad at said outer end, andsaid abrasive pad having diamond particles embedded in soft metal.

2. The tool of claim 1 wherein each of said plurality of fingers is made of a spring metal, andeach of said plurality of fingers has an outer end with an abrasive pad having diamond particles in soft metal at said outer end.

3. The tool of claim 1 wherein said outer ends of said fingers are spaced apart.

4. A tool comprising a rotatable shaft,a hub nonrotatably attached to said shaft,a spring star having a central body and a plurality of fingers extending radially outward of said central body,said central body nonrotatably attached to said hub, andan abrasive pad at an outer end of each of said fingers.

5. The tool of claim 4 wherein said outer ends of said fingers are spaced apart from each other.

6. The tool of claim 4 wherein said abrasive pads include diamond particles embedded in a metal media.

7. A tool comprising: a rotatable shaft having a longitudinal axis and a distal end,a disc at said distal end,said disc having a forward surface, anda plurality of abrasive segments around an outer circumference of said forward surface.

8. The tool of claim 7 wherein said outer circumference is divided into a plurality of spaced apart fingers, andone of said abrasive segments is attached to one of said fingers.

9. The tool of claim 7 wherein one of said abrasive segments contains a plurality of diamond particles.