Patent Application
20060076723
This invention relates in general to devices for holding a workpiece, and relates in particular to tools for holding or supporting relatively flexible stock such as rods or the like while working on the stock.
Workpiece segments frequently must be cut to a desired length from relatively flexible elongated stock. Rod stock and bar stock are two examples of elongated and relatively flexible workpieces that are available in stock lengths, from which a worker must cut a segment of desired length for a particular use. One such example is found in building construction, where cable hangers for supporting voice and data cable are being installed beneath a structural ceiling of a floor. To install such cable hangers, electricians or other workers typically will first drill a hole in the cement ceiling and then pound a steel anchor into the hole. The anchor presents female threads downwardly from the ceiling and is used for supporting a cable hanger. The worker then cuts a desired length, in many applications about 12 inches, from what is known as all-thread stock. All-thread stock refers to a rod stock threaded along its entire length. All-thread rod for many applications is made of metal, although non-metallic all-thread rod made of fiber-reinforced polymers also is known. All-thread stock typically comes in standard lengths such as six-foot lengths, from which a suitable tool, such as a hacksaw in the case of metallic all-thread rod, is used to cut off desired sections of the rod.
After cutting a section of rod, the worker then attaches two nuts to the section of all-thread stock. That attachment may be difficult because of spurs or other damage to the ends of the threaded rod, caused during the previous cutting step. After attaching those nuts, the worker screws one end of the section of rod into the anchor previously mounted in the ceiling and secures that rod with one of the nuts. The other nut then is rough-positioned on the rod section to define the height (or depth below the ceiling) of the hanger to be supported by that rod section. The worker then attaches a hanger component onto the lower end of the rod segment and secures that bracket with a third nut. The hanger component provides a mounting support, directly or indirectly, for a J-shaped bracket. The J brackets typically cradle a number of voice or data cables extending from point to point below the structural ceiling.
A problem arises when the worker cuts a rod section from the all-thread stock, e.g., with a hacksaw. Because the rod stock is relatively flexible, at least one end of the stock will flop around, delaying the cutting process. When making a cut without someone or something to hold the free end of the all-thread stock, the hacksaw blade frequently snags and extends the cutting time. If the worker has an assistant holding the free end of the all-thread stock, the need for that assistant adds to the cost of construction. Moreover, the hacksaw or other metal-cutting tool typically leaves small metal spurs on the ends of the all-thread stock, making it difficult to screw on the three necessary nuts as mentioned above.
Adding to the problem discussed above, workers are often elevated on scissor jacks or boom lifts near the ceiling, while cutting sections from all-thread stock. The frequency of the hacksaw cutting motion is sometimes close to the resonant frequency of the extended arm-platform-worker combination, causing the boom arm to bounce or sway alarmingly while the worker cuts off a section of the all-thread stock.
Stated in general terms, holding apparatus according to an embodiment of the present invention includes an element to receive a free end of a workpiece such as rod stock or the like, and an associated magnetic element for holding the apparatus onto a ferrous support surface. The magnetic element thus holds steady the workpiece receiving element and the free end of the rod stock received therein, thereby stabilizing the flexible rod stock while a worker cuts off a section from that stock. The magnetic element allows securing the holding apparatus to any conveniently-located steel or iron surface, without requiring any special connection or attachment manipulation for that purpose.
Stated in somewhat greater detail, apparatus according to an embodiment of the present invention comprises a support member having a magnetic portion for releasably holding the support member to a suitable metallic surface. An opening in the support member is configured to receive an end of an elongated workpiece of predetermined diameter or other external shape. The support member, or at least the magnetic portion of that member, preferably is enclosed within a cover of non-magnetic material, to protect the magnet and the surfaces onto which the apparatus will be magnetically attached. The external configuration of the apparatus preferably has a groove or some other manually-engageable element to facilitate removing the apparatus from a support surface in opposition to the force of magnetic attraction.
Stated in further detail, the workpiece-holding portion of the apparatus may be unthreaded so as to receive an end either of all-thread stock or unthreaded stock, or may alternatively have a threaded portion for engaging all-thread stock. In a particular embodiment of the invention, a hollow element for receiving rod stock is provided to extend through the magnetic body. One end of the hollow element is formed with threads for receiving threads on all-thread stock, and the other end of the element is unthreaded to present a relatively smooth hole. Either end may be used to hold the end of the all-thread stock during cuts, and the threaded end may be used after cutting the all thread to clean the cut end of the all-thread stock.
Accordingly, it is an object of the present invention to provide improved apparatus for holding elongated stock.
It is the other object of the present invention to provide an apparatus for holding an elongated member while that member is undergoing a cutting or other operation.
Other objections and advantages of the present invention will become more apparent from the following description of a preferred embodiment.
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The magnetic core 22 is preferably enclosed within a surrounding cover 24 to protect the magnetic core and to protect surfaces to which the holder 10 is attached. The cover 24 may be of a suitable plastic or elastomeric material, of a composition or thickness that will not prevent the magnetic core 22 from attaching the holder 10 to a ferrous surface for the intended purpose. As best seen in
A cylindrical opening 26 extends through the holder 10 from side 14 to side 16, preferably on a central axis of the holder 10. A hollow tubular insert, 28, which may be in the form of a bushing or the like, extends through the opening 26, thereby isolating the magnetic core 22 from contact with anything inserted within the opening. A first portion 32 of an interior wall of the insert 28 preferably is threaded commencing from one side 16 of the holder 10 to a point approximately half way through the opening 26, with the remainder portion 30 of the insert having a smooth or unthreaded surface. The threaded portion 32, for example, may have a ⅜ inch coarse thread corresponding to the thread present on all-thread rod of a particular size, with the unthreaded portion 30 having a diameter sufficient to receive an end of the threaded rod with a somewhat loose fit without engaging the threads. Alternately, the insert 28 could have ⅜ inch threads on the first portion 32 extending from the first side 16 and ¼ inch threads on the remaining portion 30 extending inwardly from the side 14, to accommodate two commonly-used diameters of threaded rod.
The overall size of the holder 10 is not considered critical to its operation and use, so long as the magnetic core 22 has strength sufficient to maintain the holder against a ferrous surface during use as described herein. Using a magnet made of neodymium, the overall diameter of the holder 10 would not have to be more than about 4 inches. The thickness or axial dimension of the holder 10 according to that embodiment would be approximately 1-1¼ inches, allowing sufficient length for both the smooth portion 30 and threaded portion 32 within the insert 28. It should be understood that the foregoing dimensions are exemplary only, and are not considered limiting to the invention as described.
In use, a worker desiring to cut a section, from a length of flexible product such as threaded rod 12 shown in
If a magnetic holder 10 according to an embodiment of the present invention is provided with a second threaded portion in place of the smooth portion 30, the worker will screw the rod stock into the appropriate threaded end before cutting the rod. After completing the cutting operation, the worker unthreads the cut-off section of rod and may then reverse that section to place the cut-off end in the appropriate opening of the holder, thereby cleaning the threads of that cut-off end.
The pry lever 40, in use, provides a manual gripping element in addition to the circumferential groove 20, for removing the holder 36 from magnetic attraction to a ferrous support surface 46. The pry lever 40 may thus be particularly useful, for example, where a worker is wearing heavy gloves that make it difficult to grip the groove 20 with sufficient strength to break loose the holder 36 from its magnetic attraction to the support surface 46. Using the pry lever 40, the worker first pivots the holder 36 away from the support surface 46, as indicated by arrow 48, so that a diagonally-opposite point 50 on the other side 42 of the holder 36 functions as a fulcrum around which the holder pivots as the side 42 of the holder is lifted off the support surface. The addition of the pry lever 40 thus facilitates removing the holder 36 from magnetic attraction to the support surface 46 without relying on the annular groove 20.
It should be understood that the foregoing relates only to preferred embodiments of the present invention, and that numerous changes and modifications therein may by made without departing from the spirit and scope of the present invention as defined in the following claims.
