Abstract:
Penetrators and methods of manufacturing penetrators are disclosed. One method of manufacturing a penetrator having arrowhead geometry and base geometry includes the steps: (a) cold heading a piece of material to form a blank; (b) machining the blank to create the arrowhead geometry; and (c) roll forming the blank to create the base geometry. Another method of manufacturing a penetrator having arrowhead geometry and base geometry includes the steps: (a) machining a piece of material to create the arrowhead geometry; and (b) roll forming the piece of material to create the base geometry. Yet another method of manufacturing a penetrator from a blank includes the steps: (a) machining the blank to create a first surface feature of the penetrator; and (b) roll forming the blank to create a second surface feature of the penetrator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/384,848, filed Sep. 21, 2010, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The invention relates generally to penetrators and methods of manufacturing penetrators. More specifically, the invention relates to penetrators suitable for high volume production and high volume manufacturing processes. 
     Previous methodologies used to create penetrators from metals other than lead have proven to be restrictively slow and unsuitable for high volume production. For example, one prior art manufacturing process machines penetrators from steel bar; a bar of material is fed through a single spindle machining center, and all attributes of the penetrator are machined. The finished penetrator is then parted off, leaving a small tail which is later removed in a secondary deburring process. The process is very stable and adjustable, and tooling usage is limited to cutting inserts for the toolbars. One drawback of this process is the surface footage limitation of cutting the material, which is necessary to maintain a desirable surface finish. The prior art process is time intensive and requires a large number of individual machines committed to production in order to meet practical quantity requirements. 
     SUMMARY 
     Penetrators and methods of manufacturing penetrators are disclosed. In one embodiment, a method of manufacturing a penetrator having arrowhead geometry and base geometry includes the steps: (a) cold heading a piece of material to form a blank; (b) machining the blank to create the arrowhead geometry; and (c) roll forming the blank to create the base geometry. 
     In another embodiment, a method of manufacturing a penetrator having arrowhead geometry and base geometry includes the steps: (a) machining a piece of material to create the arrowhead geometry; and (b) roll forming the piece of material to create the base geometry. 
     In still another embodiment, a method of manufacturing a plurality of penetrators from a material besides lead includes the steps: (a) providing a plurality of blanks to at least one turning center; (b) using the at least one turning center to turn a portion of the blanks to create arrowhead geometry in the blanks; and (c) roll forming the blanks to create base geometry in the blanks. The base geometry blends with the arrowhead geometry. When provided to a turning center, each blank has a generally cylindrical body portion and a nose portion extending angularly from the cylindrical body portion. Each turning center has a spindle, a clamping device, and a cutting tool. 
     In yet another embodiment, a method of manufacturing a penetrator from a blank includes the steps: (a) machining the blank to create a first surface feature of the penetrator; and (b) roll forming the blank to create a second surface feature of the penetrator. 
     In still yet another embodiment, dies are provided for use in manufacturing a steel penetrator having arrowhead geometry and base geometry from a piece of material. A first die has a surface profile with an area complementary to the base geometry, and a second die has a surface profile with an area complementary to the base geometry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a manufacturing method according to an embodiment. 
         FIG. 2  shows a portion of a cold heading machine according to an embodiment, with the die shown in section and with a piece of raw material being transferred to the die. 
         FIG. 3  shows the machine portion of  FIG. 2  during a first blow operation. 
         FIG. 4  shows the machine portion of  FIG. 2  during a second blow operation. 
         FIG. 5  shows the machine portion of  FIG. 2  during a knock-out operation. 
         FIG. 6  shows an axial view of a cold headed blank according to an embodiment. 
         FIG. 7  shows a diagram of a turning center according to an embodiment. 
         FIG. 8  shows a diagram of an alternative turning center, according to an embodiment. 
         FIG. 9  shows an axial view of a cold headed and machined penetrator according to an embodiment. 
         FIG. 10  shows a pair of dies for use in a roll forming process, according to an embodiment. 
         FIG. 11  shows an end view of the dies of  FIG. 10 . 
         FIG. 12  shows an axial view of a cold headed, machined, and rolled penetrator, according to an embodiment. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The new manufacturing methods set forth below are a combination of cold heading (or “cold forming”), turning (or “machining”), and roll forming processes  10 ,  20 ,  30  ( FIG. 1 ), and may result in reduced costs and increased production of penetrators. The cold heading process  10 , discussed below in detail, is the first step. The turning step  20  is described below before the roll forming step  30 ; however, the order of the machining and roll forming steps  20 ,  30  may be altered at the discretion of the manufacturer. A fourth step, heat treatment  40 , is also noted below and shown in  FIG. 1 . Additionally, those skilled in the art will appreciate that the ballistic shape of the penetrator is defined by the described processes, regardless of the penetrator&#39;s actual dimensions, and that any dimensions set forth below or in the drawings are only examples. “Penetrator” is used herein very broadly to refer both to ammunition that does not contain explosives as well as to other projectiles, including for example those that may contain an explosive load (e.g., in a cartridge) and those that may stay connected (e.g., by a cable) to launch equipment after being launched. 
     Attention is now directed to the cold heading process  10  with reference to  FIGS. 2 through 6 . Penetrator blanks  150  ( FIGS. 5 and 6 ) are created by feeding a coil of raw material  100  into a single die cold heading machine  105 . It should be appreciated that various cold head machines may be utilized. The machine  105  shown in  FIGS. 2 through 5  cuts a length  101  of raw material  100  from the coil and forms a blank  150  in a single die  110 . Specifically, steel raw material  100  (e.g., type A4140 or type C1055) is received as a coil. The coil&#39;s weight may be 250 pounds per coil or any other appropriate weight, and the raw material  100  may be drawn (or “extruded”) to a desired diameter by pulling the material  100  through a carbide draw die. 
     As shown in  FIG. 2 , the extruded raw material  100  is moved (e.g., by feed rollers) into the cold heading machine  105  until an end of the material  100  contacts a stop  106 . A cut off knife  108  then shears the length (or “segment”)  101  of the material  100  from the remainder of the coil. Transfer fingers  109  grasp the sheared segment  101  and locate the segment  101  in front of the die  110 . 
     The die  110  may for example consist of a carbide insert pressed into a hardened H-13 tool steel casing with a negative form of the headed blank  150  present in the carbide portion of the die. But those skilled in the art will appreciate that other types of dies may alternately be used. A diameter at a mouth  111  of the die  110  is sufficient to allow the cut off material segment  101  to fit into an exterior portion  112   a  of a cavity  112 . An angular interior portion  112   b  of the cavity  112  may begin at a point far enough from the mouth  111  to allow the entire blank  150  to be formed inside the die  110 . 
     A first blow, shown in  FIG. 3 , involves a pin  114  contacting the material segment  101  and pushing the segment  101  through the mouth  111  and into the cavity  112  of the die  110  a predetermined distance. The predetermined distance may be such that a portion of the segment  101  enters the angular interior portion  112   b  of the cavity  112 . During this action, the transfer fingers  109  disengage the segment  101  and return to their original position for grasping a subsequent segment  101 . 
     A second blow, shown in  FIG. 4 , involves a second blow pin  114   a  (or instead the pin  114 ) forcing the material segment  101  fully into the die cavity  112  to form a cylindrical blank body  150   a  and an angled nose  150   b  of the blank  150 . A knock-out pin  116  is located in stasis within the die  110  at an end of the cavity  112  opposite the mouth  111 , and a face of the knock-out pin  116  stops the segment  101  during the cavity fill propagated by the second blow. Accordingly, the distance between the face of the blow pin  114   a  at its maximum inward travel position and the face of the knock-out pin  116  determines the length of the formed blank  150 . 
     As the second blow pin  114   a  retracts from the die cavity  112 , the knock-out pin  116  becomes active and forces the fully formed blank  150  out of the die  110  in a direction opposite to the forming event, as shown in  FIG. 5 . The formed blank  150  ( FIG. 6 ) may then fall to an exit chute and roll into a pan for collection. The cold forming process  10  may be complete at this stage, yielding cycle times of, for example, two parts per second. 
     After the cold head operation  10 , the blanks (or “slugs”)  150  may be cleaned to remove residual oils and debris and sampled to ensure quality conformance. The blanks  150  may be cleaned in various manners, whether currently known in the art or later developed. For example, the blanks  150  may be washed in a soap and water mixture for ninety seconds, rinsed for thirty seconds, and dried for five minutes. 
     To ensure quality of the cold forming process  10 , blanks  150  may be gathered and examined at specific or varying intervals. In one embodiment, three consecutive blanks  150  are inspected both visually and dimensionally to ensure quality. The visual inspection may examine, for example, uniformity of the blanks  150 , the surface condition of the blanks  150 , and the overall shape of the blanks  150 . And the dimensional inspection may examine, for example, the overall length of the blanks  150 , the diameter of the bodies  150   a , the angle of the noses  150   b , the length of the angled surfaces of the noses  150   b , and the weight of the blanks  150 . As the most critical attribute of the blanks  150  may be weight, it may be particularly desirable for the weight of the headed blanks  150  to be maintained at close tolerances. Nevertheless, it may also be particularly desirable to maintain the body diameter, the total length, and other attributes of the blanks  150  within predetermined tolerances. To maintain real time capability control, all quality control data may be entered into software. 
     The cleaned and validated formed blanks  150  may be batched together and placed into feeder bowls mounted on turning machines for use in the turning process  20 . At the turning process  20 , the blanks  150  satisfactorily formed in the cold forming process  10  may each have one end (i.e., angled nose  150   b ) turned. It may be desirable for the turning machines to be multi-station modular machining centers, with each station being capable of performing a complete machining process on respective formed blanks  150 , so that multiple machined penetrators (or “turned blanks”)  250  may be produced per cycle. 
     The turning process  20  is a single point turning process, and one embodiment utilizes a plurality of turning machines (or “centers”)  210  that are CNC-controlled and have two axes (X and Z). As shown in the diagram of  FIG. 7 , each machine  210  may include slides  211 , servo motors  212 , a spindle  220  having a clamping device  225 , and tooling  230 . To provide sufficient stability and minimal variability, the spindle  220  and the tooling  230  may be assembled into a rigid frame. As will be appreciated by those skilled in the art, various tooling  230  may be incorporated to cut the formed blanks  150 . 
     Various clamping devices  225  may be used to hold the formed blanks  150  during the turning process  20 . For example, variable speed, servo controlled spindles with clamp-style work holding devices may be used. Or any other appropriate holding device, whether currently known or later developed, may instead be utilized. One clamping device  225  may typically be required for each turning center  210 . 
     In use, the formed blanks  150  may be fed into each clamping device  225  (e.g., via tubes attached to feed bowls), and the formed blanks  150  may be oriented such that the angled noses  150   b  face a predetermined direction (e.g., generally outwardly). To avoid damage to the turning centers  210  and the clamping devices  225 , safeguards known in the art or later developed may be employed to automatically cease operation of a respective turning center  210  if a formed blank  150  is fed with incorrect orientation (e.g., facing generally downwardly). 
     With the formed blanks  150  correctly oriented and secured by the clamping devices  225  at the bodies  150   a , arrowhead geometry is machined into each formed blank  150  using the turning centers  210 . In one embodiment, each formed blank  150  is held in a stable location both horizontally and vertically while spinning (e.g., at approximately 8,000 rpms) with the spindle  220 . Utilizing two axes of a respective machine  210  and the tool  230  mounted to it, the machined penetrators  250  may be created having the profile of an arrowhead by moving the cutting tool  230  simultaneously both vertically (X axis) and horizontally (Z axis) to achieve the desired geometry. The profile may be established using a set of mathematical formulas and geometric position points contained in software accessed by the machines  210 , which may guarantee that same shape is always generated, regardless of tooling or other factors. After a respective machined penetrator  250  ( FIG. 9 ) is created, it may be unclamped from the associated clamping device  225 , ejected (e.g., using a burst of compressed air), and collected. 
     While it may be desirable to use multiple turning centers  210  as described, other embodiments may employ a single turning center  210 . Further, in some embodiments (as shown in  FIG. 8 ), a turning center  210 ′ with multiple (e.g., six) modules  210   a ′ may be used—and each module  210   a ′ may respectively include the elements of a described turning center  210 . Thus, the turning center  210 ′ may functionally equate to a plurality of the turning centers  210 . 
     After the turning operation  20 , the machined penetrators  250  may be cleaned to remove residual oils and debris and sampled to ensure quality conformance. The machined penetrators  250  may be cleaned in various manners, whether currently known in the art or later developed. For example, the machined penetrators  250  may be washed in a soap and water mixture for ninety seconds, rinsed for thirty seconds, and dried for five minutes. 
     To ensure quality of the turning process  20 , machined penetrators  250  may be gathered and examined at specific or varying intervals. In one embodiment, three consecutive machined penetrators  250  are inspected both visually and dimensionally to ensure quality. The visual inspection may examine, for example, the surface finish of the machined penetrators  250 , uniformity of the machined penetrators  250 , the shape of the machined penetrators  250 , and any burrs. And the dimensional inspection may examine, for example, the overall length of the machined penetrators  250 , the arrowhead geometries of the machined penetrators  250 , and the weight of the machined penetrators  250 . To maintain real time capability control, all quality control data may be entered into software. 
     The cleaned and validated machined penetrators  250  may be batched together and placed into feeder bowls mounted on roll forming machines for use in the roll forming process  30 . At the roll forming process  30 , the machined penetrators  250  satisfactorily turned in the machining process  20  are manipulated under pressure in a consistent rolling motion between two flat dies  310 ,  320  ( FIG. 10 ) of a roll forming machine to create rolled penetrators  350  ( FIG. 12 ) having a final dimensional profile. 
     The die  310  is positioned on a ram of the roll forming machine, and the die  320  is positioned in a die pocket of the roll forming machine. Accordingly, the die  310  moves parallel to the die  320  (in the directions indicated by the arrows in  FIG. 10 ) during operation of the process  30 , while the die  320  remains stationary. 
     Each die  310 ,  320  has a desired surface profile (or “forming element”)  312 ,  322  ( FIG. 11 ) machined in relief in the die faces, and each forming element  312 ,  322  may have a taper to allow the rolled profile of completed penetrators to blend seamlessly and concentrically with the turned profile created in the turning process  20 . The profiles may blend, for example, at a point behind a ballistic nose  352  of each penetrator  350 . As shown in  FIG. 11 , each die  310 ,  320  may have a pair of forming elements  312 ,  322 , so that the dies  310 ,  320  can be inverted once one of the forming elements  312 ,  322  has reached its production life cycle. 
     In use, the machined penetrators  250  may be fed into the rolling machine by a vibratory hopper. As the machined penetrators  250  reach an end of the hopper, they are oriented to correspond to the dies  310 ,  320  and fed into the dies  310 ,  320 . For example, the machined penetrators  250  may be gravity fed through a tube until coming to a rest upon a stop that is configured to allow the machined penetrators  250  to be horizontally fed into the dies  310 ,  320 . As the ram reaches its rearward stroke, a pusher finger moves a machined penetrator  250  into the die  320 . And as the ram begins to move forward, the die  310  acquires and feeds the machined penetrator  250  into the die  320 . Pressure of the dies  310 ,  320  acting together ensures that the machined penetrator  250  enters the dies  310 ,  320  oriented in relation to the part centerline, and as the machined penetrator  250  moves into the working portions  312 ,  322  of the dies  310 ,  320 , a roll (e.g., a clockwise roll) is initiated. As the machined penetrator  250  rolls through the dies  310 ,  320  along its centerline, the working portions  312 ,  322  in the die faces manipulate the machined penetrator  250  to create the desired surface profile and establish the final diametric dimensional attributes. The resultant action of the rolling manipulation ensures that the bases  354  of the rolled penetrators  350  are properly shaped and perpendicular in relation to the penetrator centerline. Cycle time of the roll forming process  30  may be, for example, two parts per second. 
     To ensure quality of the roll forming process  30 , rolled penetrators  350  may be gathered and examined at specific or varying intervals. In one embodiment, three consecutive rolled penetrators  350  are inspected both visually and dimensionally to ensure quality. The visual inspection may examine, for example, the surface finish of the rolled penetrators  350 , uniformity of the rolled penetrators  350 , the shape of the rolled penetrators  350 , and any burrs. And the dimensional inspection may examine, for example, the overall length of the rolled penetrators  350 , the geometries of the rolled penetrators  350 , and the weight of the rolled penetrators  350 . To maintain real time capability control, all quality control data may be entered into software. 
     After the three processes  10 ,  20 ,  30 , cleaned and validated penetrators  350  may undergo a heat treatment process  40  using equipment and methods now known or later developed. 
     Very notably, the combination of the three processes  10 ,  20 ,  30  may allow penetrators to be produced at higher rates and lower costs compared to prior art manufacturing methods, and using relatively inexpensive machinery and tooling. And again, while the turning step  20  has been described above as occurring before the roll forming step  30 , the order of the machining and roll forming steps  20 ,  30  may generally be altered at the discretion of the manufacturer. Because the turning process  20  and the roll forming process  30  may each be responsible for distinct portions of the final geometry, the order of steps  20 ,  30  typically is not critical. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of the present invention. Embodiments of the present invention have been described with the intent to be illustrative rather than restrictive, and alternative embodiments that do not depart from the invention&#39;s scope will become apparent to those skilled in the art. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the present invention. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.