Cutting by use of rotating axially moving tool – With work-engaging structure other than tool or tool-support – Frictionally engaging sides of opening in work
Reexamination Certificate
1999-09-07
2001-03-27
Bishop, Steven C. (Department: 3722)
Cutting by use of rotating axially moving tool
With work-engaging structure other than tool or tool-support
Frictionally engaging sides of opening in work
C408S201000, C408S229000
Reexamination Certificate
active
06206618
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to devices and methods for cutting, boring and reaming pipes or tubes, and more particularly to a rotary pipe cutting apparatus for removing portions of broken plastic pipe from the bore of an outer pipe or fitting.
2. Description of the Background Art
The use of plastic pipe for irrigation and landscape sprinkler systems has become widespread due to the lower cost of plastic pipe compared to galvanized metal pipe. Polyvinyl chloride (PVC) and acrylonitrile-butadiene-styrene (ABS) plastics are the most widely utilized materials for fabrication of plastic pipes. One drawback associated with plastic pipe, however, is that it provides lower strength than galvanized metal pipe, and thus irrigation and sprinkler systems employing plastic pipe can be more prone to breakage and require more frequent repair. A common example of this problem is provided by a standard lawn sprinkler system wherein a sub-ground plastic pipe network includes several “T” fittings which extend upward towards the ground surface for attachment of sprinklers. The sprinklers are generally attached to the “T” fittings by means of a plastic riser pipe sized to fit within the inner diameter of the “T” fittings and which are glued into the “T” fittings. If a sprinkler is inadvertently kicked or struck by a lawn mower or bicycle, the plastic riser pipe may break off and leave a broken portion glued within the “T” fitting. The broken portion of riser pipe prevents attachment of a new riser and sprinkler to the “T” fitting. To repair the break and replace the sprinkler, one must dig around the “T” fitting, cut the pipe around the “T” fitting, and then install couplings, a short length of pipe, and a new “T” fitting. This procedure is expensive, time consuming, and inconvenient. The use of threaded risers and “T” fittings has been introduced to facilitate the replacement of broken risers, but the broken threaded portions of such risers often cannot be successfully removed from the threaded “T” fitting without damaging the “T” fitting, and thus the above-described inefficient procedure must still be used.
Several cutting, reaming, boring and chamfering tools have been developed to aid in removal of broken sections of plastic pipe from the bore of an outer pipe or pipe fitting. Typically, such tools are rotary in nature and employ one or more blades which cut or grind away the inner, broken pipe portion from the outer pipe. The currently available cutting devices, however, have proven deficient for various reasons. Particularly, the presently used devices are difficult to guide and control during cutting, and can damage the outer pipe or fitting during removal of the broken inner pipe. Another problem is that the individual devices are usually configured to remove an internal broken pipe portion of only a certain wall thickness or size, and cannot effectively remove inner pipe with a different wall thickness. Still another problem experienced with currently used cutting devices is that the shavings or turnings produced during cutting are not directed away from the cutting site but, instead, tend to be retained adjacent the blade or blades, and thus the device must periodically be withdrawn from the outer pipe during a cutting operation to clean the blade or blades and remove shavings.
Yet another problem experienced by currently used cutting devices is that the depth that the device extends into the bore of the pipe or fitting can not be accurately limited thereby causing damage to the interior surfaces of the fitting or pipe.
Accordingly, there is a need for a rotary pipe cutting apparatus which provides for removal of broken plastic pipe from an outer pipe or fitting, which does not damage the outer pipe, which can be used to remove broken pipe of different wall thickness, and which does not cause buildup of shavings adjacent to the cutting blade or require periodic removal of shavings during a cutting operation. The present invention satisfies those, needs, as well as others, and generally overcomes the deficiencies found in the background art.
BRIEF SUMMARY OF THE INVENTION
The present invention pertains to a rotary pipe cutting apparatus which removes a broken section or portion of plastic pipe from the bore of an outer pipe without damaging the outer pipe, which provides for automatic removal of shavings from the cutting site during cutting operations, and which meets or exceeds the dimensional pipe sizing requirements dictated by ASTM D-1785. The apparatus can also be used to remove the inner threads from a threaded outer pipe for conversion into a slip fitting.
In general terms, the invention comprises a cylindrical body having a cutting blade and a longitudinal slot, a sizing and depth guide member included on the lower end of the body, a stopping member included on the upper end of the body, and a shank or rod on the upper end of the body for attachment to a rotational power source. By way of example, and not of limitation, the body of the apparatus is sized generally to the outer diameter of the broken pipe to be removed and slightly less than the inner diameter of the exterior pipe or fitting. The slot in the body extends longitudinally from the lower end to the upper end of the body, and is angularly offset relative to the rotational axis of the body. Preferably, the slot is tapered in depth and width from the upper end to the lower end of the body to aid in removal of shavings from the blade and adjacent areas. The cutting blade is adjacent to the slot and to the lower end of the body, and extends or protrudes outward radially and downward from the slot.
The guide member is of generally cylindrical configuration, and is sized to the inner diameter of the broken pipe to be removed. The guide member, in the preferred embodiment, has a disc shaped base that has a diameter slightly smaller than the diameter of the pipe to be extracted. The base is coupled to a central cylindrical barrel that has a plurality of resilient projections having arcuate surfaces biased outwardly from the surface of the sides of the barrel. In use, the projections of the guide member are compressed within the bore of the pipe thereby centering the guide member and resisting movement of the guide and body from the center. The projections also allow the device to be used on a wider range of inner pipe thicknesses. The barrel is coupled to the body on one side and to the base member on the other.
The stop member preferably comprises an annular flange which extends outward radially from the body along the upper end thereof. The shank or shaft on the upper end of the body is structured and configured to be received by a conventional collet or spindle on a power drill or other rotational power source.
The invention is used by selecting a body with a guide member which is sized to match the inner diameter of the broken pipe to be removed from an outer pipe or pipe fitting. The shank is attached to a conventional power tool, and the body of the apparatus is then inserted into the outer pipe, and positioned so that the guide member enters the bore of the inner, broken pipe. Rotary power is applied to the apparatus, and the cutting blade cuts or grinds away the inner, broken pipe. The guide member centers the body and holds the body in place during cutting so that the cutting blade does not inadvertently cut into or damage the outer pipe. The longitudinal slot allows shavings from the cutting blade to be directed upward past the upper edge of the body and away from the cutting operation. The angle and tapered shape of the slot facilitate removal of shavings or cuttings from the blade. The stop member prevents the apparatus from cutting further into the inner, broken pipe section than is required for replacement with another pipe section, so that time is not wasted cutting away more of the broken inner pipe than is necessary or cutt
Bishop Steven C.
O'Banion John P.
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