Abstract:
An annular core cutting apparatus includes a cutting head including a generally cylindrical sidewall having a first end and a second end, wherein the first end has a cutting edge, and wherein the sidewall includes a plurality of openings having at least one sharpened edge. A spindle is coaxially and rigidly coupled to the second end of the cylindrical sidewall, and the spindle configured to rotate about a rotational axis. In a further embodiment, a generally conical member is disposed within the cutting apparatus to assist with grinding and removal of waste material.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to machining technology and, more particularly, to automated core machining of materials such as foam and honeycomb-core materials. 
       BACKGROUND 
       [0002]    When performing automated machining of certain materials, such as foam and honeycomb-core materials (generally referred to as “core” materials), certain geometries may be encountered that are difficult or impossible to produce using standard circular disk cutters. That is, the head of such cutters are prone to impacting the core and inadvertently damaging or destroying the workpiece. 
         [0003]    Conventional core machining is done with the cutter positioned at 90 degrees to the workpiece, and this angular relationship is maintained throughout the machining operation. Referring to  FIG. 1 , for example, a workpiece  102  is machined using a cutting head  104  including a cutting disk  106  attached to a rotating spindle  105 , wherein spindle  105  has a rotational axis  110 , and wherein the cutting direction  112  of cutting head  104  is substantially perpendicular (within a small lead angle θ) to rotational axis  110 . Stated another way, rotational axis  110  of spindle  105  is maintained, during a cutting operation, substantially normal to the plane of the work surface  103 . In this illustration, “combing” or “trailing” cutting paths are exclusively used for carving of the core. Complex geometry cannot be reached in this fashion. Furthermore, the sidewalls of workpiece  102  (e.g., surface  113 ) cannot be cut without rotating spindle  105  by approximately 90 degrees. 
         [0004]    Accordingly, it is desirable to provide improved core machining tools and methods. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
       BRIEF SUMMARY 
       [0005]    The present invention generally relates to an annular core cutting apparatus capable of machining core workpieces along an orientation parallel to the cutting surface. In accordance with one embodiment, for example, a core cutting apparatus includes a cutting head including a generally cylindrical sidewall having a first end and a second end, wherein the first end has a cutting edge, and wherein the sidewall includes a plurality of openings having at least one sharpened edge. A spindle is coaxially and rigidly coupled to the second end of the cylindrical sidewall, and the spindle configured to rotate about a rotational axis. In a further embodiment, a generally conical member is disposed within the cutting apparatus to assist with grinding and removal of waste material. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
           [0007]      FIG. 1  is an overview of a typical prior art circular disk cutting operation; 
           [0008]      FIG. 2  is a core carving apparatus in accordance with one embodiment of the present invention; and 
           [0009]      FIG. 3  is an overview of a core carving operation in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. For the sake of brevity, conventional techniques related to computer-aided manufacturing (CAM), machining, and other conventional tools and techniques may not be described in detail herein. 
         [0011]    In general, the present invention relates to an improved core cutting apparatus that allows cutting of parts traditionally difficult or impossible to cut due to cutter limitations and/or physical machine head size. The annular cutter of the present invention is capable of machining core in an orientation that is parallel to the cutting surface, rather than perpendicular to the cutting surface as with prior art systems. 
         [0012]    Referring to  FIG. 1 , a core cutting apparatus generally includes a cutting head  206  which is rigidly and coaxially secured (using any convenient method) to a spindle  202 . Spindle  202 , during normal operation, spins at an appropriate rate, and may be attached to a variety of manipulators, controllers, computers, and the like. In one embodiment, for example, spindle  202  is coupled to a five-axis manipulator of the type well known in the art. 
         [0013]    Cutting head  206  includes a generally cylindrical sidewall  208  having any convenient length and diameter, depending upon the cutting application. Cutting head  206  is thus generally ring-shaped, or “annular.” One end of sidewall  208  has a cutting edge  220 , which is serrated, saw-tooth-shaped, or has any suitable texture or geometry capable of cutting a core-type material. In this regard, the term “core” or “core-type” material refers to a material that has an internal, often regular geometric structure, rather than a homogeneous, contiguous structure. Such structures include, for example, honeycomb-shaped structures and the like. Materials such as Kevlar, steel, aluminum, or any other plastic, metal, or ceramic may be used. 
         [0014]    Cutting head  206  is suitably attached to spindle  202  either removeably or permanently, through any suitable hardware arrangement (e.g., using a chuck and shank configuration, etc.). Spindle  202  and cutting head  206  thus together rotate (either in one direction or both directions) with respect to a rotational axis  204 . The speed of rotation will vary depending upon the application, but in various embodiments ranges upwards of 10,000 to 15,000 RPM. 
         [0015]    Sidewall  208  further includes one or more openings  210  (or “flutes”) that extend through the thickness of the sidewall. These openings function, in part, to allow cut-away material (or “offal”) to be removed from cutting head  206  during operation. There may be any number of such openings, depending upon the application, and the openings may have any convenient shape. In the illustrated embodiment, for example, a total of four generally spiral-shaped openings are distributed uniformly around the surface of sidewall  208 . In this embodiment, slightly less than half of the cylindrical surface area of sidewall  208  is taken up by openings  210 ; however, the present invention is not so limited, and comprehends any number of openings having any suitable shape, size, and distribution. 
         [0016]    In one embodiment, all or a portion of openings  210  have sharpened or chamfered edges. For example, in  FIG. 2 , region  212  within each opening  210  is sharpened. Such an embodiment is useful when the tool is designed to rotate in a single direction (in this case, clockwise as viewed down spindle  202  to cutting head  206 ). These edges may include any suitable structure, including saw-teeth, serrations, etc. 
         [0017]    In a further embodiment, a generally conical member  230  is coupled to spindle  202  and/or cutting head  206  adjacent to the end opposite cutting edge  220  (e.g., region  232 ). Conical member  230  preferably acts to break up cut-away material prior to it being ejected through openings  210 . In this regard, conical member  230  may comprise, for example, a silicon-carbide grinding surface, such as a surface with screw-like serrations. Conical member  230  need not be actually conical in shape: it may have any curvilinear or rectilinear shape capable of assisting with radial movement of offal through the interior of cutting head  206  during operation. 
         [0018]    The various subcomponents of cutting head  206  may be manufactured using any suitable material or combination of materials. In one embodiment, for example, sidewall  208  and conical member  230  are fabricated from a high-speed steel and/or silicon-carbide material. 
         [0019]    Having thus given a description of a cutting apparatus of the present invention, it can be seen that this arrangement provides certain advantages when machining core materials. Referring to  FIG. 3 , for example, a workpiece  102  has a surface  103  which, as described early with respect to  FIG. 1 , cannot easily be cut using traditional disk cutters. 
         [0020]    As shown, however, a cutting head  206  in according with the present invention moves downward along a cutting direction  112  that is actually substantially parallel to (minus a small lead angle) the rotational axis  204 . It will be noted that the size and shape of openings  210  in the embodiment shown in  FIG. 3  is somewhat different from that shown in  FIG. 2 . That is, simple rectangular openings  210  with sharpened edges on both sides of the opening are used. As illustrated, the system is able to make plunge cuts (i.e., cuts consisting of simple downward motion), but is also capable of fabricating fine edge geometries using a proper manipulator path. 
         [0021]    It should also be appreciated that the illustrated embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.