Abstract:
An apparatus for use in filling and capping artillery charge system modules or the like including a lower fixture carried by a base plate for receiving a module with an open center core tube and fixing the module in place relative to the base plate for filling and capping. An upper fixture is carried by a pivot plate for capping a filled module, the pivot plate being hingedly attached with respect to the lower fixture to enable the upper fixture to swing clear of the lower fixture during module loading and thereafter addressing a fixed module to cap same. The lower fixture further includes a centering rod that carries a peripherally disposed flexible expanding member and a shaped cam lock member which operate the expander member to receive, lock and unlock a center core tube to the centering rod to capture and fix the module in place. The cam lock member also aligns the system for lid insertion by an adjustable stroke air cylinder mounted on the pivot plate.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The present invention relates generally to propellant charge systems for large caliber artillery pieces, more particularly, to modular artillery charge systems or MACS, and involves improvements in a load, assembly and packaging process for manufacturing field modular charge units for singular and multi-unit propellant charge systems. Specifically, the invention is directed to an improved alignment fixture which fixes the relative positions of the case and core tube during the time the case is filled and further facilitates the lid to be guided into place and inserted with precision. 
     II. Related Art 
     Propellant charges for cannon artillery systems, primarily large caliber weapons systems such as 155 mm howitzers, etc., typically include plurality of coordinating modular charge units serially loaded behind the shell. The individual modular charge units are generally cylindrical in shape, frequently having a length to diameter ratio approaching 1. A central axial opening is provided through each unit to facilitate ignition of that and consecutive units. Such a system concept is illustrated, for example, by Reinelt, et al., in U.S. Pat. No. 4,702,167. 
     Particular embodiments of such modular units are of a three-piece design, which includes a combustible case body, normally of nitrocellulose, having a closed end and an open end, a combustible cap or lid adapted to fit or nest in and seal into the open end of the case body, and a perforated combustible central or core tube which fits over raised rims in the central bores of and connects the central openings provided in the closed ends of both the relatively rigid case body and lid to form a continuous central bore for containing core igniter bags. Top and bottom recesses are provided to accommodate two end igniter bags. This assures proper ignition of a number of serially placed modular charges. Up to eight modular charges may be employed in firing a 155 mm howitzer, for example. 
     The MACS load, assemble and pack process utilizes a series of discreet workstations, each of which is designed to accomplish a specific operation on the case, charge and additive materials. The present invention deals primarily with the provision of a significantly better approach to one difficult manual portion of the process including an operation at a loading station in which the case and core tube must be held in precise alignment during filling and during the operation in which the lid or cap is guided and inserted into place to seal the modular unit. 
     In the past, the operation has presented problems. No positive positioning devices existed and the central tube or core was placed over the rim or lip extension of the opening formed in the bottom of the case by hand and held in place while a weighed amount of propellant was poured about the tube to fill the case. Proper alignment was thus dependent on the repetitive skill of the operator. This had to be done while the assembly was vibrated to achieve proper propellant density. After the case was filled, the lip of a central opening in the cap or lid had to be fit over the central tube and the edge nested inside the case sidewall. Of course, if the central tube was not axially aligned so as to be concentric with the lid or cap and case, when the lid was fitted to the filled case and installed into the top of the case and over the top of the core tube, the core tube and lid could be easily damaged resulting in rejection of the module. This occurred often enough to be considered a severe defect in the process, one for which there was a definite need for a solution. 
     Accordingly, it is a primary object of the present invention to provide a system that automatically provides and maintains proper alignment among the case body core tube and lid during filling and capping assembly of a MACS charge. 
     It is a further object of the present invention to provide alignment an fixture that is capable of maintaining alignment of top and bottom protrusions utilized in lid/case body assembly in certain MACS charges, such as the XM 231 and XM 232 howitzer charges. 
     A further object of the present invention is to provide an alignment fixture that holds the case and lid in the specific orientation and utilizes a locking and expanding mandrill to center the core tube in position. 
     A yet still further object of the present invention is to provide an alignment fixture which holds the case and lid in a specific orientation utilizing a locking and expanding mandrill to center the core tube wherein the mandrill further acts as a guide for the lid as it is being inserted. 
     Another object of the present invention is to provide an alignment fixture which includes a holding fixture for the lid equipped with a device that inserts the lid in the case body to a controlled depth. 
     Still another object of the present invention is to provide an alignment fixture and system in which, once the case is loaded with propellant, the fixture is closed and the lid insertion is performed automatically. 
     An additional object of the present invention is to provide a mechanized processing station that includes an alignment fixture and lid insertion device that prevents core tube and/or lid damage during filling and capping assembly of modular units. 
     Additional objects and advantages regarding the fixture system of the invention will become apparent to those skilled in the art upon familiarization with the specification, drawings and claims associated with this specification. 
     SUMMARY OF THE INVENTION 
     The present invention provides solutions to several severe problems encountered in production of modular artillery charge system propellant units and specifically problems stemming from an inability to maintain proper alignment of the parts during manual loading and capping operations by the provision of a mechanized system including an alignment fixture which simplifies and improves the alignment of the case body and center case tube during loading and guides the lid into place during the lid insertion operation or capping step. 
     The alignment fixture is an assembly including a metal base member which may be machined aluminum base having a bottom and sidewall adapted to receive the lower portion (bottom and partial sidewall) of the modular unit case body of the MACS charge. The fixture base includes a central bore for receiving an elongated centering rod or spindle directed up through the center of the case body and carries a flexible peripheral member or expander which is expanded by a similarly shaped cam lock member which fits over the upper centering rod to positively position the upper portion of the center core tube or ignition tube. The cam lock portion of the mandrill is tapered at the upper end and also acts as a guide for the lid as it is being inserted. The cam lock member or mandrill operates vertically to lock and unlock the module core tube. The holding fixture for the lid is equipped with a fluid operated, preferably, an air cylinder of adjustable stroke that inserts the lid in the case body after the fixture is closed. The stroke depth of the cylinder is controlled with cam operated limit valves that may be adjusted to insert the lid to a specific depth in the case body. This device further aligns cap protrusions with case recesses in accordance with the desired orientation for insertion of the lid. 
     In operation, after the operator has placed the case body in the alignment fixture, the core tube is inserted over the raised cam lock member or mandrill and the lower end of the core tube is properly seated over the lower extension in the case body. The mandrill is lowered to expand the flexible peripheral member to fix the orientation of the upper portion of the core tube with respect to the alignment fixture. The alignment fixture is attached to a vibration table which is initiated while the operator loads the case with a pre-weighed amount of propellant thereby assuring proper propellant fill. After the propellant is loaded, the pivot plate is rotated to a latched position above and parallel to the base plate. 
     After that, the lid insertion is performed automatically by activation of the air cylinder and the vibration table is shut off at the end of the cycle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, wherein like numerals depict like parts throughout the same: 
     FIG. 1 is a cross section view of an individual propellant charge module of a class suitable to be manufactured using the fixture of the system of the invention; 
     FIG. 2 is a perspective view of a center core tube in accordance with the charge module unit of FIG. 1; 
     FIG. 3 is a perspective view of a lid for the modular unit of FIG.  1 . 
     FIGS. 4 a  and  4   b  are views, partially in section, showing the holding and centering portion of the fixture of the invention in the unlocked and locked positions, respectively; 
     FIG. 5 is a side elevational view, partially in section of the alignment fixture of the invention; and 
     FIG. 6 is a top view of the alignment fixture of FIG.  5 . 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1-3 depict a typical modular artillery charge system (MACS) charge unit, usable alone or serially with various numbers of other units in a plurality of propellant-loading configurations as a propellant charge for large cannons such as the 155 mm howitzer. It will occur to those skilled in the art that the system and method associated with the present invention are usable for processing a variety of these types of charges and that the charge of the detailed description is meant as an example and not by way of limitation. 
     The modular charge unit and elements depicted in FIGS. 1-3 is included herein as an illustrative example of a charge unit which can be produced using the fixture system of the present invention. Additional details of such modular charge units are found in U.S. Pat. No. 5,747,723 issued to Gregory Buckalew et al., which is incorporated herein in its entirety by reference for any reason. The illustrated charge unit is intended as an example and not by way of limitation with respect to the present invention. 
     Thus, FIG. 1 shows a modular propellant charge unit including a unit body or shell  10 , center core tube  12 , and a cap  14  as the basic parts thereof. As can be seen from the figures, each of these is generally made up of a thin-walled hollow cylinder which, in the case of the center core tube  12 , has two open ends. The body  10  and cap  14  each have an open end and a closed end. As seen in the figures, the open end of cap  14  fits into and seals the open end of the body  10  and the closed ends of both cap  14  and body  10  describe central openings with short tubular extensions. As further depicted in FIG. 1, the center core tube  12  is positioned longitudinally in the body  10  and receives tubular extension  16  defining the center open portion of the body  10  and tubular extension  18  defining the center open portion of the cap  14  at  18  in the assembled modular unit. The remaining portion of the body  10  is shown filled with a propellant material as at  20 . The body, core and lid are generally made of combustible nitrocellulose coated with an environmentally stable protective coating shown about the periphery of FIG. 1 at  22 . Typically, the body  10  and cap  14  each have a wall thickness between 2.0 mm and 2.7 mm. The dimensions and density of the body  10 , core tube  12  and cap  14  must be within a very close tolerance to insure durability, critical functioning of the igniter and complete combustion. A core igniter bag  24  flanked by end igniter bags  26  and  28  is illustrated to make up the igniter system in FIG.  1 . The make up and function of the igniter material is well known to those skilled in the art as is the composition of the main propellant charge and these details do not form a part of the present invention. 
     FIG. 2 depicts the center core tube or ignition tube  12  as a thin-walled cylinder with two open ends. The center core tube  12  typically has a wall thickness slightly less than that of the body  10  (typically 1.3-1.8 mm) may have a diameter of 17.7 mm to 31.8 mm. These dimensions are based on a 155 mm module and the devices have evolved and are designed in accordance with a large amount of accumulated interior ballistic knowledge or lore. As can be seen in FIG. 3, the central portion of the cap  14  continues the hollow-center core ignition system through an opening  40  and includes a conical recessed section  42  and a tubular extension or raised rim  18  which is designed to be accommodated in one end of the center core tube  12 . The cap  14  further includes a series of protuberances or protrusions  44  disposed equally about the periphery of the open end of the cap and extending radially from the exterior surface. The protrusions  44  are designed to be accommodated or received in a groove  46  located in the body  10  (FIG. 1) so that the lid  14 , when inserted, can be snapped into place. Once installed, a great deal of force is required to remove the lid from the modular body. 
     FIGS. 5 and 6 depict one embodiment of the filling and capping alignment fixture of the invention depicted generally by  50  and including a bottom or horizontal bed plate  52  to which the remainder of the assembly is fixed and which is designed to attach to a vibrating table. A pair of spaced support members, one of which is shown at  54 , are fixed to the bed plate as by countersunk cap screws  56 . These members of the assembly carry an upper or pivot plate  58  mounted on a pivot arm system  60  adapted to pivot relative to the members  58  on a pair of bushing and shoulder screw arrangements, one of which is illustrated at  62 . The system also includes a pivot plate latching mechanism, including a pair of spaced latches, one of which is shown at  64  and which are pivotally mounted at  66 , preferably also by a shoulder screw and bushing arrangement. A pair of strikers, one of which is shown at  68 , are carried by the pivot plate  58  and a latch rod is illustrated at  70 . A cam follower arm operated interlock switch  72  is provided with a spring plunger  74  in conjunction with a control valve shown at  76 . This arrangement accomplishes and verifies the latching of the pivot plate in the lowered position for the cap insertion step to be described. 
     An air cylinder assembly is also mounted on the pivot plate  58  and includes a fluid operated cylinder, which may be an air cylinder shown in the retracted position at  78 . The cylinder is provided with a follower arm  80  which is connected as by a rubber bumper  82  to a cam member  84  which, in turn, operates a follower wheel  86  to pivot a connected switch arm  88  which, in turn, operates a valve  89 . This system is adjustable to control the stroke of the air cylinder  78  in the capping operation. 
     The MACS body alignment module includes a case base receiving formed member  90  for receiving the bottom portion of the case of an initially unfilled propellant module as shown at  10 . The base form has a central recess  92  containing a bore in which a centering rod or spindle  94  is mounted by means of a reduced diameter lower threaded portion  96  secured as by a hex nut  98 . The centering rod  94  also has a reduced upper diameter at  100  which is adapted to receive the lower portion of a flexible core centering member  106  and the central bore of a similarly shaped vertically operating cam lock member  102 . The shape of the lower portion of the cam lock member  102  is beveled at  104  to cooperate with the flexible peripheral member  106  to expand the upper portion of the peripheral member  106  to flare against and positively position a center core tube  12  when the cam lock member is in the fully inserted or lowered position and resting against the lower portion of the member  106 . 
     The system is illustrated in the unlocked position in FIGS. 4 a  and  5  and in the locked position in FIG. 4 b.  The alignment fixture for the base is shown enlarged in FIGS. 4 a  and  4   b,  respectively in the locked and unlocked positions to better illustrate the details. 
     The fixture also includes a cylindrical case mid-side guide surrounding the mid portion of the module case at  110  having a lower portion configured to match the module base receiving form  90  and is beveled inwardly at the upper end at  112  in a manner so as to cooperate with a matching cylindrical top case guide member  114  having a downward directed, outwardly beveled surface  116  which matches the surface  112  and to provide self-alignment includes a recess containing an O-ring at  117 . The O-ring  117  retains a module lid or cap  14  in the upper case guide  114  prior to insertion by the stroke of a ram device  122  which has a bottom surface that matches the upper surface of the cap  14 . Top case guide member  114  is further provided with a plurality of side vent openings, one of which is shown at  118  and is fixed to the pivot plate  58  by a plurality of threaded members, one of which is shown at  120 . 
     The air cylinder  78  also carries a case ram device  122  fixed thereto as by threaded fasteners, one of which is shown at  124  and which is employed to push the cap  14  into place to seal the modular body  10  after loading. The length of the down stroke can be adjusted and is controlled by the follower arm and cam-operated control valve  89 . 
     A side bumper is illustrated at  126  and screws, or the like, for fixing the pivot arm  60  to the pivot plate  58  are shown at  128  in FIG. 5. A pair of threaded fasteners, typically hex nuts  130 , are shown in the top view of FIG. 5 for retaining the spaced strikers  68 . 
     FIGS. 4 a  and  4   b  depict the mechanism for holding the modular case  10  with core tube  12  in a fixed, centered position for loading and capping. The figures are partially in section and show the device with the cap already in place and the side guide removed. Note that in the unlocked position of FIG. 4 a,  the cam lock member  102  is raised an amount and the peripheral flexible member  106  is in its relaxed and unflared position. Void spaces appear at  130  and  132 . In FIG. 4 b,  the cam lock device is completely lowered, the beveled edges  104  expanding the flexible peripheral member  106  into contact with the intercore tube  12  in a manner which forces the tube  12  to be centered about the reduced upper diameter  100  of the centering rod  94 . Not only does this fix the modular case  10  in place for loading, but it also defines the proper clearance about the upper portion of the cam lock member  102  at  134  to accommodate the central tubular extension  18  of the cap  14 . This, together with the operation of the pivot plate of the alignment fixture, assures proper insertion of the cap  14  after completion of the loading operation. 
     In operation with the bed plate mounted on a vibrating table in a well known manner and, with the pivot plate pivoted upward and away from the MACS alignment module, a MACS case  10  is placed on the case base and a mid-side guide  110  is placed over the case base  90  and capturing case  10  with center core tube  12  in place, the cam lock member is lowered thereby centering the core tube  12 . Energetic material is then added about the periphery of the center core tube filling the casing  10  with the desired weight of propellant of energetic propellant material. The energetic material may consist of any suitable main charge propellant pursuant to the particular modular charge being processed. This is done with the vibrating table operating so that the propellant granules are properly accommodated in the volume of the module. Once this is accomplished, a lid cap  14  is placed over the system and guided into a central location by the beveled edges  112  of the mid-side guide  110 . Thereafter, the pivot plate may be pivoted into place and properly latched. This allows the valve  76  to enable the operation of the air cylinder  78  to operate the ram member  122  over the predetermined stroke distance to push the cap  14  into the top of the case  10  as guided by the guide member  114  and central locking cam member  102 . In this manner, the fixture of the invention provides exact alignment among the center core tube, outer module case and inner and outer rims of the cap. Once the cap or lid member  14  is pushed the proper distance into place, the piston of the air cylinder  78  will retract pulling with it the ram member  122  and the pivot plate can thereafter be raised and the cam lock member unlocked so that the filled module can be removed from the fixture and another empty case placed for loading. 
     It will be appreciated that the elements of alignment fixture of the invention need to be of a conductive material so that any static electricity generated by the operation of the process is conducted away from the module being loaded and assembled. Thus, the bed and pivot plates are typically made of aluminum alloy and as is the base portion  90 , the mid-case guide  110  and the ram  122  are typically of conductive polyethylene materials. 
     While the device of FIGS. 5 and 6 illustrates a fixture for processing an XM-232 MACS with very slight modifications in the ram and case base receiving member XM-231 MACS, one other module can be processed as well. 
     This invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.