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Title:
BOILER TUBE CUTTING APPARATUS
Document Type and Number:
WIPO Patent Application WO/1995/026849
Kind Code:
A1
Abstract:
A boiler tube-wall cutting apparatus, comprising: a frame (12), a movable carriage (10) supported on said frame and adapted to move along a linear path passing through a tube-wall which is to be cut, means (20, 22) for guiding said carriage along said linear path to substantially eliminate movement of the carriage except along said linear path, articulated support means (14, 41, 80) for supporting said frame on a boiler tube-wall, said support means including a mounting bracket (80) for mounting said cutting apparatus to a boiler tube-wall, and a support arm (14), one end of which is pivotally secured to said mounting bracket (80), said frame (12) being pivotally secured to the other end of said support arm (14), and cutting means (52) secured to said movable carriage.

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JPS61188016PIPE MACHINE
Inventors:
HILLESTAD, Tollief, O.
Application Number:
PCT/US1995/004167
Publication Date:
October 12, 1995
Filing Date:
April 04, 1995
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HILLESTAD, Tollief, O.
International Classes:
B23D45/00; B23D45/02; B23D59/00; (IPC1-7): B23D45/00; B23D45/02; F22B37/00
Domestic Patent References:
WO1987002302A1
Foreign References:
US5199221A
GB2054441A
US4979294A
US3667855A
US5033347A
Download PDF:
Claims:
WHAT IS CLAIMED IS;
1. A boiler tubewall cutting apparatus, comprising: a frame, a movable carriage supported on said frame and adapted to move along a linear path passing through a tubewall which is to be cut, means for guiding said carriage along said linear path to substantially eliminate movement of the carriage except along said linear path, articulated support means for supporting said frame on a boiler tubewall, said support means includ ing a mounting bracket for mounting said cutting appara¬ tus to a boiler tubewall, and a support arm, one end of which is pivotally secured to said mounting bracket, said frame being pivotally secured to the other end of said support arm, and cutting means secured to said movable car¬ riage.
2. A tube cutting apparatus as set forth in Claim 1, further comprising means operable to effect movement of said carriage along said linear path.
3. A tube cutting apparatus as set forth in Claim 2, wherein said operable means comprises a rack, having a plurality of teeth, a fixed longitudinally along the bottom of said carriage, and a pinion gear centrally located on said frame, the teeth of said pinion gear engaging the teeth of said rack, whereby rotation of said pinion gear causes meshing of said pinion gear with said rack to effect movement of said carriage along said linear path.
4. A tube cutting apparatus as set forth in Claim 1, wherein said guide means comprises a pair of spaced parallel rods, mounted to said frame, and passing through a corresponding pair of cylindrically bored guides attached to said carriage, said bores being dimensioned to allow said carriage to be moved only along said linear path parallel to said rods.
5. A tube cutting apparatus as set forth in Claim 1, wherein said cutting means is a motor driven rotating abrasive wheel .
6. A tube cutting apparatus as set forth in Claim 1, wherein said cutting means is a motor driven rotating carbide disk.
7. A tube cutting apparatus as set forth in Claim 1, wherein said cutting means is powered by a pneumatic motor.
Description:
BOILER TUBE CUTTING APPARATUS

FIELD OF THE INVENTION

This invention relates to an apparatus for cutting boiler tube-walls such as are common at power generating stations. More specifically, the present invention relates to a compact, light weight apparatus for supporting cutting means for liner motion along a fixed plane relative to the axial direction of the tubes of a tube-wall.

BACKGROUND OF THE INVENTION

In certain industrial process plants, as for example, in steam generating plants, it often becomes necessary to cut out and replace sections or panels of a boiler tube-wall which have rusted or otherwise become damaged or deteriorated. Tube-wall sections are gener¬ ally removed by using either hand held tools such as motor driven saws or cutting torches, or more desirably by using any of various track mounted cutting apparatus¬ es. Hand held tools are generally undesirable, especially for removing more than a single tube from a tube-wall, because they tend to produce uneven cuts which make it difficult to weld a replacement tube-wall section onto the existing tube-wall. Track mounted cutting apparatuses such as those disclosed in U.S. Patent No. 5,033,347 are preferred when relatively large sections of tube-wall, such as sections more than 3 feet in length, are to be removed. Conventional track mounted boiler cutting apparatus are however, relatively heavy, bulky and awkward, and require a relatively substantial amount of time and labor for installation and set-up. Accordingly, such track mounted apparatuses are not ideally suited for removing relatively short sections of boiler tube-wall.

A portable tube cutting apparatus having a vice-like fastener for supporting the apparatus from a stationary object, such as the tube which is to be cut, is disclosed in U.S. Patent No. 5,199,221. The dis- closed apparatus can be used to cut the tube which supports the apparatus as well as other adjacent tubes in close proximity. The device however is not generally suitable for cutting along a section of tube-wall wherein the individual tubes are continuously connected to an adjacent tube by a membrane, and wherein the tubes are generally too closely spaced to one another to permit use of the vice-like fastener for supporting the cutting apparatus on one of the tubes.

Accordingly, it would be highly desirable to provide a tube cutting apparatus which is lighter, more portable, and easier to install and set up than conven¬ tional track mounted cutting apparatuses, and which can be quickly and stably fastened to a tube-wall to allow a smooth even cut. Such apparatus would be particularly desirably in those situations where a relatively short section of tube-wall is to be removed, such as less than about 3 feet of tube-wall.

SUMMARY OF THE INVENTION The present invention provides a relatively portable tube cutting apparatus which is especially useful for cutting relatively short sections from a tube-wall. The apparatus includes a carriage which upon a motorized cutting means is securely attached, with the carriage being movably supported on a frame to allow movement of the carriage along a linear path relative to the frame, and articulated support means for securing the frame to a tube-wall. The articulated support means allows the apparatus to be fastened to a fixed point on the tube-wall while allowing lateral repositioning of the cutting means relative to the tube-wall. The apparatus provides means whereby a smooth even cut of up to about a 3 foot length can be made in a boiler tube-

wall more quickly and easily than was previous possible using conventional track mounted boiler tube cutting apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top is view of the cutting appara¬ tus;

FIG. 2 is a side elevational view of the cutting apparatus shown in Figure 1;

FIG. 3 is a bottom plan view showing the frame rotated approximately 40° with respect to the articulated fastening means; and

FIG. 4 is a side elevational view similar to FIG. 2 showing the apparatus secured to a boiler tube- wall with a pneumatic saw secured to the cradle of the cutting apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The cutting apparatus broadly comprises a carriage 10 adapted for movement in a linear direction relative to a frame 12 which has articulated support means for securing the device to a boiler tube-wall.

Referring to the figures generally, the carriage 10 has a flat rectangular base with upwardly projecting supports 16 onto which a cutting tool 52 (shown in FIG. 4) is placed. The cutting tool 52 is securely fastened onto the carriage 10 with fasteners 18 which are connected to the supports 16 by screws or other suitable means. Various other means, such as straps, may be used for securing the cutting tool 52 to the carriage. A pair of block-shaped guides 20 project upwardly from opposite sides of the carriage 10. Each guide 20 has a bore extending therethrough in a direc¬ tion parallel to the direction of the cutting tool path. A bushing is inserted into each bore to provide a smooth non-abrading interior bore surface through which one of a pair of parallel guide rods 22 pass. The parallel guide rods 22 are mounted to the frame 12 by means of posts 24 with the axes of the rods being parallel with the direction of the cutting tool path. The guides 20

and rods 22 restrict movement of the carriage 10 to a single linear path relative to the frame 12. The posts 24 also act as stops to define the extent to which the carriage is permitted to travel along the linear path. The diameter of the rods 22 are in close tolerance with the dimensions of the busing surface to eliminate movement of the carriage 10 with respect to the frame 12 except in the direction parallel to the axes of the rods 22. Various other guide means for restricting the movement of one part of an apparatus to a single direc¬ tion with respect to another part, such as those used on sliding drawers, would also be suitable for use with the invention.

The device is preferably provided with a rack 26 and pinion gear 28 arrangement which is operative to advance the carriage 10 and attached cutting tool 52 along a linear cutting path parallel to the axes of the rods 22. The pinion gear 28 is centrally located on the frame 12 and engages the teeth 30 of rack 26 which is affixed longitudinally along the bottom of the carriage 10. The pinion gear 28 can be rotated by turning lever 32 operatively secured by hub 34 to a transverse rod 36 passing through a bearing opening in a side wall of frame 12 and axially secured to pinion gear 28. Rota- tion of pinion gear 28 causes meshing of pinion gear 28 with rack 26 to effect movement of the carriage 10 relative to the frame 12 along the linear cutting path. The pinion gear may be power operated, although hand controlled rotation is preferred. Alternative means for advancing the carriage, such as a screw drive, gears, and/or chains, are well known and are therefore considered to be within the scope of the invention. While the carriage 10 is preferably advanced by means of a rack and pinion gear mechanism, the invention is capable of functioning without any special means for advancing as by merely pushing the carriage forward by hand.

The cutting apparatus is fastened or secured to a tube-wall bank by means of an articulated support means including an arm 14 which is pivotally connected at one end to frame 12 by means of a bolt or threaded rod 41 fixedly depending from a central portion of the frame and passing through a hole or bore in arm 14. A nut 42 is used to fix the frame 12 relatively to the arm 14 once a desired spacial orientation of the frame rela¬ tively to the arm has been achieved. A mounting bracket 80 is pivotally connected to the other end of arm 14. Mounting bracket 80 includes a mounting plate 82 preferably having a pair of vertically elongated slots 84, each of which is adapted to receive a heavy duty adjustment bolt 86 welded to a back plate 88. The mounting bracket 80 also includes a journal block 90 fixedly secured to the mounting plate 82 by suitable means such as threaded fasteners 92. The journal block 90 has a central vertical through bore 91 through which passes a depending rod 94 which is fixedly secured to arm 14 such as by pins 96. Depending rod 94 includes a smooth relatively larger radius portion, the outer surface of which acts as a bearing surface against the through bore 91, and a threaded reduced diameter portion for fixing the relationship between the arm 14 and the mounting bracket 80 by means of nut 100 after arm 14 has been rotated to a desirable position relative to mount¬ ing bracket 80. The back plate 88 is welded or other¬ wise secured to the boiler tube-wall as shown in FIG. 4. Either of nuts 42 and 100 can be replaced with a nut 102 having an integrally attached handle 104 which is pivotally connected to nut 102 by means of a pin 106. The above nut-wrench combination allows for quick loosening, repositioning and refixing of the apparatus as desired without the need for separate tools. The articulated support means of the invention allows the cutting tool to be rotated and moved lateral¬ ly relative to a fixed point of securement of the apparatus to a boiler tube-wall while allowing rotation

of the cutting means relative to the support means, thereby providing an apparatus which is capable of quickly and easily providing a relatively long, smooth, even cut through a boiler tube-wall. Referring to FIG. 4, the device is preferably used in association with a cutting tool having a rotat¬ ing circular blade 54 or disk operatively actuated by a power source such as a motor 56. The preferred motor 56 is a pneumatic motor typically comprising a multiple vane air driven motor and powered by compressed air ordinarily available in industrial plants. A satisfac¬ tory pneumatic motor for use in the present invention generates about 3 to about 7 and desirably from abut 4.5 to about 5.5 horsepower and about 3,500 to about 6,500 and desirably from about 4,500 to about 5,500 RPM at a standard factory air pressure of about 90 psi.

For safety reasons, the device preferably has a blade guard 58 attached to the carriage 10 and cover¬ ing that portion of the blade facing the operator. The major components of the device, such as the frame 12, arm 14 and carriage 10 are preferably machined from aluminum. Aluminum is preferred because it has a good balance of desirable properties, such as light-weight, high-strength, toughness and corrosion resistance. The replaceable grip pads are preferably made from carbon steel because of its relatively low cost and toughness.

To further reduce the weight of the device without deleteriously effecting its structural strength, holes 60 are preferably provided in selected locations on the carriage 10 and frame 12.

Although the present invention has been de¬ scribed for use in cutting vertical tubes, it is readily apparent that horizontal tubes or other axial direction- al tubes can be cut in accordance with the present invention.

While in accordance with the patent statutes the best mode and preferred embodiment has been set

forth, the scope of the invention is not limited there¬ to, but rather by the scope of the attached claims.