The present invention relates in general to a positioner and cutting apparatus. More specifically, the present invention relates to an automatic conduit cutting apparatus for the Heating, Ventilating and Air Conditioning (HVAC) industry, wherein a plurality of conduits are cut to optimum lengths to provide internal reinforcements of ducting.
Ductwork is utilized to facilitate the heating, ventilation and cooling of various buildings, both residential and commercial. The ductwork typically comprises individual duct sections which are then coupled together to form a continuous, largely airtight duct for conveying a moving mass of air.
The duct sections are typically made from strong, yet relatively light, material such as sheet metal, or the like. It is an important design characteristic that the duct remain as lightweight as possible in order to minimize the size and weight of fasteners and other structural components required to support the ductwork, as well as maintaining materials and fabrication costs of the ductwork itself at reasonable costs.
Commonly utilized ductwork often have rectangular, circular or oval cross sections, and are frequently manufactured and supplied in pre-cut lengths or sections with transversely outwardly protruding interconnection flanges provided at opposite longitudinal ends of the section, to facilitate interconnecting duct sections at a job site, and thus form the finished air conveying ducts of desired lengths.
Whatever the size or shape of the ductwork, the relatively small thickness of the walls of the ductwork, as compared to its cross-sectional dimensions, results in the duct walls being rather flexible. Conventional ductwork may therefore experience large, possibly destructive and oftentimes loud structural deformations if static or dynamic air pressure differentials between the interior and the exterior of the ductwork exceeds a predetermined threshold value. For this reason, mechanical engineering standards (e.g., standards written by the Sheet Metal and Air Conditioning Contractor""s National Association or SMACNA), as well as most building codes, require that certain ductwork be reinforced against expansion and/or collapse.
These reinforcements can be either internal or external. External reinforcements may be accomplished by using various structural shapes such as bars, angle iron or the like. Internal reinforcements generally include structures, such as conduit or threaded rods, that span the width or height of the ducting and are attached to the ducting side walls.
One known internal reinforcement mechanism for ductworks is shown in FIG. 1 and includes a threaded tie rod 2 oriented between opposite planar sides of a rectangular duct 4. Fixed, inner washers 6 are disposed adjacent the interior side of the opposing duct walls 4, while exterior washers 8 are disposed on the exterior of the duct walls 4 in matching relation to one another. As shown in FIG. 1, a threaded nut 10 is screwed down against each of the exterior washers 8 to secure the reinforcing tie rod in position.
There are several variations of the reinforcing mechanism shown in FIG. 1 and these variations may also include rubber O-rings or other elastic sealing devices disposed between the washers and the duct walls. Moreover, it is also known to replace the fixed, inner washers 6 with threaded nuts or lock nuts which may then be tightened in association with the tightening of the exterior threaded nuts 10 to provide the necessary rigidity to the reinforcing mechanism.
FIG. 2 illustrates a cross-sectional view of another known internal reinforcing mechanism which is comprised of a metallic tube 10 and an insert 12. After the insert 12 has been disposed within the tube 10, the tube 10 is crimped so as to deform in a radially inward direction. The crimped section of the tube 10 becomes locked within an annular groove 14 which has been inscribed about the periphery of the insert 12, thus locking the insert 12 within the tube 10. A threaded bolt 14 extends from the insert 12 and would extend beyond the exterior of a duct wall to be secured thereto via a threaded nut, or the like. The insert 10 may also include an inner cavity to accommodate an unillustrated biasing member, such as a spring, wherein the spring would outwardly bias the bolt 16 for greater flexibility. The insert 12 may be made from a metallic material or from a plastic or polymer material.
FIGS. 3 and 4 illustrate two embodiments of cross-sectional views of an internal reinforcing mechanisms as described in Patent Application No. 60/412,722, titled xe2x80x9cDuct Reinforcement Rodxe2x80x9d, filed on Sep. 23, 2002 and incorporated herein in its entirety by reference. As depicted in FIG. 3, the reinforcing rod 20 includes a metal tubing or conduit 22 and a standard bolt or jam nut 24. As illustrated in FIG. 3, the conduit 22 and the bolt 24 are sized so that the head 26 of the bolt 24 enjoys a tight fitting relationship with the inner diameter of the tubing 22 when the conduit 22 is pressed over the head 26. It will be appreciated that the length of the threaded section of the bolt 24 extends beyond the conduit 22 and may be varied in accordance with the specific design characteristics of the ductwork and the relative length of the bolt 24 utilized. Additionally, both a first and a second crimp, 30 and 32 respectively, are disposed above and below the head 26 to ensure against longitudinal movement of the bolt 24 within the conduit 22.
FIG. 4 illustrates an internal reinforcing rod 40 utilizing a threaded nut 42 in place of the bolt 24 shown in FIG. 3. As depicted in FIG. 4, the conduit 22 is pressed over the nut 42 and the conduit 22. In similar fashion to FIG. 3, both a first and a second crimp, 30 and 32 respectively, are disposed above and below the nut 42 to ensure against longitudinal movement of the nut 42 within the conduit 22.
Prior art software is generally utilized to determine the ductwork requirements for an entire project or job, such as the ductwork required in the construction of a new building. Problematically however, internal reinforcement requirements, such as size, quantity and length of conduits or the like, are not included in prior art software packages.
Moreover the raw materials, such as the threaded rod or conduit used in the reinforcement mechanisms illustrated in FIGS. 1-4, are generally sold in lengths that far exceed the assembled lengths of the reinforcement mechanisms. For example, xc2xd inch or xc2xe inch nominal diameter conduit is generally sold in 10 foot lengths. Accordingly, even after the internal reinforcement requirements are calculated, the net lengths of each reinforcement must be cut from the 10 foot lengths of raw conduit. This can not only be a very time consuming and expensive process, it can also generate a lot of wasted conduit if care is not taken to determine the optimum cut lengths per 10 foot length based on the particular reinforcement requirements of a job. This problem of generated waste can be especially problematic for larger jobs, such as the construction of a large building.
With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a conduit cutting apparatus which overcomes the above-described drawbacks while maximizing effectiveness and flexibility, and minimizing waste in the assembling process.
The present invention offers advantages and alternatives over the prior art by providing a computerized positioning and cutting apparatus for automatically cutting structures to predetermined lengths with a minimum amount of scrap for a given project. The apparatus includes a frame. A positioning trough is supported by the frame. A magazine is mounted to the frame, which is sized to receive uncut lengths of structure to be selectively fed to the positioning trough. A drive system is mounted to the frame and operatively connected to a positioning system for selectively positioning the uncut structures in the trough. A cutter is mounted on the frame to cut the structures as the positioning system feeds the structures in discreet lengths through the trough. A controller having an associated computer system is in electrical communication with the drive system and the cutter. The associated computer system calculates the optimum number of cuts per a predetermined uncut length of structure to produce a minimum amount of waste structure for the project.
In an alternative embodiment of the invention the positioning and cutting apparatus is a conduit cutting apparatus, and the structure is conduit to be used for internal reinforcement of HVAC ducting.
Another embodiment of the invention is provided in a method of cutting conduit for internal reinforcement requirements of HVAC ducting with a minimum amount of scrap for a given project. The method includes inputting project specifications into a computerized system associated with a controller of a conduit cutting apparatus. Ductwork requirements are then calculated for the project from the specifications. Internal reinforcement requirements are also determined for the ductwork. Then the optimum number of cuts per each predetermined length of uncut conduit to minimize scrap for the project are calculated. The computer determined amount and size of uncut conduit is loaded into the conduit cutting apparatus. The conduit cutting apparatus is then operated though the controller to produce the internal reinforcement requirements with the least amount of scrap conduit for the project.
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