Abstract:
A method of reducing foreign object debris (FOD) during drilling operations is provided. The method includes disposing a vacuum housing with a computer aided design (CAD) formed drill template in an operative position on a work piece, actuating a vacuum operatively connected to the vacuum housing, thereby creating negative pressure between the template and the work piece, the negative pressure acting on the debris resulting from the drilling operations, and enhancing the negative pressure without manipulating the vacuum.

Description:
BACKGROUND 
       [0001]    The present disclosure generally relates to manufacture and assembly of structures and, more particularly, to drilling holes into a part at precise locations and angles. The disclosure further relates to the collecting of debris, for example, as generated when drilling into a composite or metallic aircraft part. Such debris includes one or more of composite dust, metallic drill chips, water, and any other lubricating or cooling fluids generated by the drilling process. 
         [0002]    In conventional practice, before a pattern of holes is drilled in a part to be assembled into a structure, a template, or jig, is made and placed on the surface of the part to be drilled. For example, in the aerospace industry, the structure, or assembly, may be a composite aircraft skin over an aluminum substructure. Examples may also be found in the marine and refrigeration industries, such as applications to boat hulls and heating/air conditioning ducts. The template or jig contains holes conforming to the desired hole pattern that is to be made on the surface of the part to be drilled. A drill is then inserted, typically manually by a drill operator, in each hole of the jig and is used to drill a hole into or through the part. 
         [0003]    The drilling process generates particles of material, such as metal and composite debris, from the structure. For example, aircraft skin often includes composite materials—such as carbon and epoxy—which release a dust of fine particles when drilled through. Additionally, water or other fluids may be used during drilling to reduce heat created by the drilling process. For health and safety reasons, operators are required to collect the carbon epoxy dust with a vacuum collection system during the drilling process. Prior art templates generally include a flat plate with a separate vacuum system where the operator or operators must position the template and operate a drill separately from the vacuum system. If the templates do include a vacuum system, there often is a loss in suction due to the open holes that allow for drilling. Additionally, cleanup of the drilling often is labor intensive as well as time intensive as water and particles that may have not been captured by the vacuum could escape through the currently unused drill holes in the template. 
         [0004]    As can be seen, there is a need for a template for drilling a pattern of holes in a structure and for collecting debris generated by the drilling process without the time and costs associated with clean up. There is also a need for a drill template with an integral vacuum collection system that allows for a stronger suction via the vacuum. 
       BRIEF DESCRIPTION 
       [0005]    In one aspect, a method of reducing foreign object debris (FOD) during drilling operations is provided. The method includes disposing a vacuum housing with a computer aided design (CAD) formed drill template in an operative position on a work piece, actuating a vacuum operatively connected to the vacuum housing, thereby creating negative pressure between the template and the work piece, the negative pressure acting on the debris resulting from the drilling operations, and enhancing the negative pressure without manipulating the vacuum. 
         [0006]    In another aspect, a drill template for placement adjacent a structure is provided. The drill template includes a vacuum housing comprising a structure contact surface defined to fit adjacent a mold line surface of the structure, a vacuum port extending from the vacuum housing, a plurality of drill bushings extending through the vacuum housing from an outer surface to an inner surface of the vacuum housing, the drill bushings in fluid communication with the vacuum port, and at least one drill bushing plug operable for insertion into one of the drill bushings. The drill bushing plugs are operable for preventing ingress or egress of fluid or debris through the drill bushing into which the drill bushing plug is inserted and further operable for increasing a draw through another of the drill bushings when a vacuum is attached to the vacuum port. The vacuum housing, the vacuum port, the drill bushings, and the at least one drill bushing plug are concurrently fabricated using an additive manufacturing process. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a top view of a drill template. 
           [0008]      FIG. 2  is a bottom view of the drill template of  FIG. 1 . 
           [0009]      FIG. 3  is an oblique view of the drill template of  FIG. 1 . 
           [0010]      FIG. 4  is a view of the drill template of  FIG. 1  including a plurality of drill bushing plugs inserted therein. 
           [0011]      FIG. 5  is an oblique view of the drill template of  FIG. 1  positioned on a surface of a structure. 
       
    
    
       [0012]    The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the present invention or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following detailed description is of the best currently contemplated mode of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0014]    Broadly, one embodiment of the present invention provides a template for precisely drilling a pattern of holes in a structure and for collecting debris generated by the drilling process including plugs for insertion into holes that are not being used during specific portions of the drilling process. The structure may be part of a product manufactured in the aerospace, marine, or refrigeration industries as typified by, for example, a skin portion attached to a frame substructure. Drill templates are generally useful in such situations for drilling holes in precise locations through the skin and into or through a portion of the frame, for example, for attaching the skin to the frame with fasteners received by the holes. The skin or structure may have a precisely defined exterior surface, referred to as an outer mold surface, mold line surface, or outer mold line (OML). 
         [0015]    A drill template includes a contact surface such that a substantially exact fit is achieved between the mold line surface and the contact surface of the drill template. For example, the drill template may be built directly from computer aided design (CAD) engineering solid models using an additive manufacturing process, for example, selective laser sintering (SLS). Although SLS is used as an example throughout to illustrate a type of fabrication process that is compatible with CAD techniques for fabricating a drill template, other types of additive manufacturing processes could be utilized as well. For example, fused deposition modeling (FDM) and stereo-lithography (SLA) fabrication processes also could be used. These and other processes vary only by the method that they fabricate the parts and the materials that they use. More importantly, all the named processes are of the type that include the generation of parts directly from a CAD model. 
         [0016]    Referring now to  FIGS. 1 through 3 , in which like items are referenced with the same numeral throughout, a drill template  100  is illustrated in accordance with one embodiment. Drill template  100  may include a vacuum housing  102  having a top surface  104  and an interior surface  106 . Vacuum housing  102  may include side skirts  108  and  110 , and end skirts  112  and  114 . Each of skirts  108 ,  110 ,  112 , and  114  may have a contact surface  116 . For example, skirt  108  may have contact surface  109 , skirt  110  may have contact surface  111 , skirt  112  may have contact surface  113 , and skirt  114  may have contact surface  115 , so that contact surfaces  109 ,  111 ,  113 , and  115  collectively form contact surface  116  of housing  102 . Contact surface  116  may be formed using CAD techniques to conform to the CAD engineering solid model of the outside mold line surface of a structure, such as outside mold line surface  118  of structure  120  shown in  FIG. 5 , which, for example, may be part of an aircraft fuselage. 
         [0017]    Vacuum housing  102  includes an integral vacuum attach, or vacuum port  122 . Vacuum port  122  may include an external, round opening  124 , seen in  FIG. 3 , that may communicate through skirt  114  to an opening  126 , seen in  FIG. 2 , at the interior surface  106  of vacuum housing  102  to provide vacuum from an external vacuum system through opening  124  to opening  126 . Vacuum port  122  may be attached to a vacuum hose of a vacuum system so that vacuum may be applied through the hose to the interior vacuum chamber, described above, between structure  120  (shown in  FIG. 5 ) and drill template  100 , for removing and collecting drilling debris concurrently with the drilling operation. 
         [0018]    Vacuum housing  102  includes drill bushings  130 , which may be formed to pass through vacuum housing  102  from top surface  104  to interior surface  106 . Drill bushings  130  may be formed so that a drill bit may be inserted into drill bushing  130  and guided by drill bushing  130  to form a precisely placed hole in structure  120 . 
         [0019]    Vacuum housing  102  may also include one or more drill support attachments  134 . A drill support attachment  134  may be positioned near a drill bushing  130 . A drill support attachment  134  may be locked onto a drill to help control the placement of a drill bit within one or more of drill bushings  130 . 
         [0020]    Vacuum housing  102  may include index holes  138  which may extend from top surface  104  to contact surface  116 , as shown in  FIG. 2 . Index holes  138  may be formed to receive an alignment pin  140 , as shown in  FIGS. 1 ,  2 , and  3 . Alignment pins  140  may be temporarily inserted into an index hole drilled in structure  120 , including a skin portion of structure  120  or a substructure portion of structure  120 . Alignment pins  140  may inserted into index holes  138  to help position and align template  100  so that the holes located by drill bushings  130  may be formed in the desired positions. 
         [0021]    Vacuum housing  102  also may include one or more edge of part locators  142 . Edge of part locator  142  may be formed, for example, as shown in  FIGS. 1 through 3 , so that it may fit against an edge of structure  120  at a precise location so that drill template  100  may be located precisely at a pre-defined location relative to structure  120 , further helping to position and align template  100  so that the holes located by drill bushings  130  may be formed in the desired positions. Edge of part locator  142  may be formed using CAD techniques to form edge of part locator  142  using the CAD engineering solid model of structure  120  so that edge of part locator  142 , and thus vacuum housing  102 , fits to a precise location relative to structure  120 . Vacuum housing  102  may be fabricated, for example, from nylon using a selective laser sintering process in conjunction with CAD techniques to achieve an exact fit, i.e., being formed using the same CAD solid model as is used to form structure  120 , of edge of part locator  142  with the structure  120 . The exact fit of edge of part locator  142  to a precise location of structure  120  may enhance the positioning and drilling accuracy of drill template  100 . 
         [0022]    Vacuum housing  102  may include standoff buttons  144 . Standoff buttons  144  may be formed on interior surface  106  of vacuum housing  102 , as shown in  FIG. 2 . Standoff buttons  144  may be used to hold structure  120  steadily in place when a hole is drilled in structure  120  guided by one of the drill bushings  130 . For example, an aircraft skin included in structure  120  may be flexible and may bend when a hole is drilled into it. A standoff button  144 , however, may hold the aircraft skin so that when the hole is drilled in the skin, the skin may not push back against the drill and change the shape of the drilled hole. Generally, holes drilled in aircraft structures are required to meet tight tolerances in shape and dimension and it may be undesirable to have the hole move during the drilling process. 
         [0023]    As shown in  FIGS. 1 through 3 , vacuum housing  102  of template  100  may be formed from three sections  150 ,  152 , and  154 . Sections  150 , 152 , and  154  may be attached together to form drill template  100  so that vacuum housing  102  may have dimensions, for example, within a range of 30 inches to 45 inches. Sections  150  and  152 , or sections  152  and  154 , may be held together via fastener arms  146 , which may be molded as an integral part of the structure of sections  150 , 152 , and  154 . Fasteners  148 , which may be nut and bolt fasteners, for example, may be inserted in fastener arms  146  and used to hold sections  150  and  152 , and sections  152  and  154 , together. 
         [0024]      FIG. 4  is an illustration of one embodiment of vacuum housing  102  that is fabricated to include one or more plugs  200  that are insertable, for example, into drill bushings  130 . Plugs  200  may be fabricated, for example, from nylon using a selective laser sintering process in conjunction with CAD techniques to achieve an interference fit in the drill bushings  130 . For example, plugs  200  may be formed using the same CAD solid model as is used to form structure drill template  100  and vacuum housing  102 , and further may be concurrently fabricated with vacuum housing  102 . Alternatively, plugs  200  may be fabricated independently from the fabrication of the drill template  100  and vacuum housing  102 . 
         [0025]    The insertion fit of plugs  200  into one or more of drill bushings  130  of the vacuum housing  102  improves the suction of the vacuum generated at the unplugged drill bushings  130 . Moreover, the fit of the plugs  200  into the vacuum housing  102 , and the resultant increase in suction may eliminate or decrease any debris or water escaping these unused drill bushings  130 . The plugs  200  may be attached to the vacuum housing  102  via a coupling device  202  such as a string, a small cable, or a small chain. Alternatively, the plugs  200  may be inserted into the drill bushings  130  with no attachment to the vacuum housing. 
         [0026]      FIG. 5  is an illustration of one embodiment of drill template  100  placed on a structure  120 , the drill template  100  having a contact surface  116 . Contact surface  116  may be formed using CAD techniques to conform to the CAD engineering solid model of the outside mold line surface of a structure, such as outside mold line surface  118  of structure  120 , which, for example, may be part of an aircraft fuselage. Drill template  100  may be secured to structure  120 , for example, using pin clamps  160 , inserted, for example, in index holes formed in drill template  100  and structure  120 . 
         [0027]    Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
         [0028]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.