Patent Abstract:
An apparatus that includes a frame structure, a plurality of suction cups and a clamp assembly. The plurality of suction cups are coupled to the frame structure and are operable in an energized mode for securing the apparatus to a first structure. The clamp assembly is coupled to the frame structure and exerts a clamping force onto a second structure when the suction cups have secured the apparatus to the first structure. The clamping force is of sufficient magnitude to retain the second structure in a predetermined position relative to the first structure. An optional tool may be included to perform a desired operation and an optional conveyance mechanism may be employed to selectively position the tool relative the frame structure. A method for coupling a first structure to a second structure is also provided.

Full Description:
[0001]    This is a division of U.S. patent application Ser. No. 09/664,077 filed Sep. 18, 2000 entitled “VACUUM CLAMP DEVICE”. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to clamping tools and more particularly to a tool and method for clamping two structures together with vacuum clamps and performing an operation on them.  
         BACKGROUND OF THE INVENTION  
         [0003]    In the manufacture of modern aircraft, it is fairly common to utilize automated riveting processes to fasten several components together. In such operations, a first component, such as a longeron, may be clamped into a fixture or jig so as to conform to a desired contour, while a second component, such as a skin, is clamped to the first component. Several holes are typically formed into the components and temporary fasteners are employed to retain the components together during the automated riveting process.  
           [0004]    In many instances, the clamps that are employed to retain the second component to the first component, as well as the fixturing, may not be capable of exerting sufficient clamping force onto the components to eliminate gaps between the components during the forming of the holes for the temporary fasteners. Consequently, gaps are formed during the drilling process as a result of the various forces that are exerted onto the components (e.g., the force exerted by the cutting tool). Gaps between the components permit the chips that are formed during the drilling step to migrate between the components. As such, it is necessary that the components be off-loaded from the fixture, deburred, cleaned and re-loaded to the fixture prior to the installation of the temporary fasteners.  
           [0005]    Accordingly, there remains a need in the art for a tool that can provide sufficient clamping force to the components so as to eliminate the formation of gaps between the components during a drilling operation.  
         SUMMARY OF THE INVENTION  
         [0006]    In one preferred form, the present invention provides an apparatus for securing a first structure to a second structure and performing an operation on the first and second structures. The apparatus includes a frame structure, a plurality of suction cups, a clamp assembly, a conveyance mechanism and a tool. The plurality of suction cups are coupled to the frame structure and are operable in an energized mode for securing the apparatus to the first structure. The clamp assembly is coupled to the frame structure and exerts a clamping force onto the second structure when the suction cups have secured the apparatus to the first structure. The clamping force is of sufficient magnitude to retain the second structure in a predetermined position relative to the first structure. The tool is configured to perform the operation. The conveyance mechanism is coupled to both the frame structure and the tool and enables the tool to be selectively positioned relative to the frame structure.  
           [0007]    In another preferred form, the present invention provides a method for coupling a first structure to a second structure. The method includes the steps of: providing a tool apparatus having a plurality of suction cups and a clamp assembly; energizing the plurality of suction cups to secure the tool apparatus to the first structure; employing the clamp assembly to exert a force onto the second structure that retains the second structure to the first structure; forming a hole through the first and second structures; inserting a fastener through the hole and fastening the first and second structures together; and removing the tool apparatus from the first structure after the first and second structures have been fastened together.  
           [0008]    In yet another preferred form, the present invention provides an apparatus for securing a first structure to a second structure and performing an operation on the first and second structures. The apparatus includes a frame structure, a plurality of suction cups and a clamp assembly. The plurality of suction cups are coupled to the frame structure and operable in an energized mode that for securing the apparatus to the first structure. The clamp assembly is coupled to the frame structure and includes a fluid power cylinder having a rod that is movably coupled to the frame structure. The fluid power cylinder is operable in a first mode for moving the rod toward the second structure and exerting a clamping force that is of sufficient magnitude to retain a mating surface of the second structure against a mating surface of the first structure. The fluid power cylinder is also operable in a second mode for moving the rod away from the second structure.  
           [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:  
         [0011]    [0011]FIG. 1 is a perspective view of a tool apparatus constructed in accordance with the teachings of the present invention in operative association with a pair of structures that are to be coupled to one another;  
         [0012]    [0012]FIG. 2A is a side elevation view of a portion of the tool of FIG. 1 illustrating the suction cups in an unenergized mode;  
         [0013]    [0013]FIG. 2B is a side elevation view similar to that of FIG. 2A but illustrating the suction cups in an energized mode;  
         [0014]    [0014]FIG. 2C is a portion of a side elevation view illustrating a clamp assembly having a resilient member;  
         [0015]    [0015]FIG. 3 is a side elevation view similar to that of FIG. 2A but illustrating a spring-biased clamp assembly;  
         [0016]    [0016]FIG. 4 is a side elevation view similar to that of FIG. 2A but illustrating a clamp assembly having a fluid power cylinder;  
         [0017]    [0017]FIG. 5 is a rear elevation view of the tool of FIG. 1 in operative association with the pair of structures that are to be coupled to one another;  
         [0018]    [0018]FIG. 6 is a cross-sectional view taken along the line  6 - 6  of FIG. 5; and  
         [0019]    [0019]FIG. 7 is a side elevation view of a portion of the structures illustrated in FIG. 1 after they have been coupled together. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    With reference to FIG. 1 of the drawings, a tool apparatus constructed in accordance with the teachings of the present invention is generally indicated by reference numeral  10 . Tool apparatus  10  is illustrated in operative association with a relatively flexible skin member  12  and a relatively stiff longeron  14 . Those skilled in the art will understand that the illustration of tool apparatus  10  in conjunction with skin member  12  and longeron  14  is merely exemplary and not intended to limit the scope of the present invention in any manner.  
         [0021]    Tool apparatus  10  is shown to include a frame structure  20 , a plurality of suction cups  22 , a plurality of clamp assemblies  24 , a tool  26  and a conveyance mechanism  28 . Frame structure  20  includes a U-shaped frame member  30  and a pair of handles  32 . Frame member  30  is preferably formed from a stable but lightweight material, such as aluminum or magnesium, so as to provide a stable foundation onto which the other components of tool apparatus  10  may be mounted, as well as to minimize the mass of tool apparatus  10 . Handles  32  are positioned on opposite side of frame member  30  in a manner which permits a technician to ergonomically lift and operate tool apparatus  10 .  
         [0022]    The suction cups  22  are coupled to frame structure  20 , with each of the suction cups  22  being supported by a suction cup holder  36 . Suction cup holders  36  include a hollow cavity  38  which causes them to be in fluid connection with a respective one of the suction cups  22 . An air line  40 , a vacuum generator  42  and a switch  44  are coupled to frame structure  20  which are employed to selectively operate suction cups  22  in an energized mode. Actuation of switch  44  causes pressurized air in air line  40  to flow through vacuum generator  42  and generate a corresponding supply of vacuum power. Vacuum power is transmitted through vacuum conduits  46  to each of the plurality of suction cups  22 . When suction cups  22  are placed against a structure, such as skin member  12 , the air contained between the structure and the vacuum fastener  22  is evacuated, causing the air pressure that acts of the opposite side of the structure to push the structure against the vacuum fastener  22 . Suction cups  22 , suction cup holders  36 , vacuum generators  42  and switches  44  are both well known in the art and commercially available and as such, need not be discussed in greater detail herein.  
         [0023]    Each of the clamp assemblies  24  is coupled to frame structure  20  and is adapted to exert a clamping force onto longeron  14  when suction cups  22  have been placed in the energized mode to secure tool apparatus  10  to skin member  12 . The clamping force exerted by the clamp assemblies  24  is operable for retaining longeron  14  in a predetermined position relative to skin member  12 , preferably such that no gap exists between the mating surfaces  50   a  and  50   b  of skin member  12  and longeron  14 .  
         [0024]    In the particular embodiment illustrated, each of the clamp assemblies  24  includes a pin  24   a  that is fixed to frame structure  20  and extends therefrom by a predetermined distance as best shown in FIGS. 2A and 2B. However, those skilled in the art will understand that clamp assemblies  24  may be constructed somewhat differently to render tool apparatus  10  more tolerant of variation between skin member  12  and/or longeron  14 , easier to set-up and/or easier to operate. In this regard, the clamp assemblies  24  preferably include an adjustment means, such as an externally threaded collar and an internally threaded receiver, which cooperate to permit the distance between the frame structure  20  and the longeron  14  to be adjusted to a desired distance. Additionally or alternatively, suction cup holders  36  may also include an adjustment means to permit the distance between suction cups  22  and frame structure  20  to be adjusted to a desired distance. Also alternatively, the clamp assemblies  24  may include a resilient element  24   b  as shown in FIG. 2C, which will deflect at a predetermined rate when the clamp assembly  24  contacts the longeron  14 . Although resilient element  24   b  is shown to be a rubber leg  24   c , those skilled in the art will understand that resilient element  24   b  may also be a conventional compression spring (not shown).  
         [0025]    In FIG. 3, an alternate clamp assembly  24 ′ is illustrated as including a pin member  60  and a spring member  62 . Pin member  60  is movably mounted to frame structure  20  such that its distal end  64  may be moved between a retracted position and an extended position. Spring member  62  is mounted to tool apparatus  10 ′ and exerts the clamping force onto pin member  60 .  
         [0026]    In FIG. 4, another alternate clamp assembly  24 ″ is illustrated as including a fluid power cylinder  70  having a housing  72  that is mounted to frame structure  20 , a piston  74  that translates within a hollow cavity  76  formed into housing  72  and a rod  78  that is fixedly coupled at its proximal end to piston  74 . Fluid power cylinder  70  may be operated in a first mode wherein compressed air is introduced into a first portion  80  of housing  72 . The compressed air generates a force which acts on piston  74  to cause piston  74  to move toward the distal end of housing  72 . As piston  74  and rod  78  are fixedly coupled to one another, movement of piston  74  will cause rod  78  to move toward and contact longeron  14 . Fluid power cylinder  70  may also be operated in a second mode to cause the piston  74  (and rod  78 ) to move toward the proximal end of housing  72 . In the particular embodiment illustrated, operation of fluid power cylinder  70  in the second mode entails the venting of the first position of housing  72  to permit a spring member  82  that is contained within housing  72  to exert a force onto the distal face of piston  74  to cause piston  74  to move toward the proximal end of housing  72 . Those skilled in the art will understand that the operation of the fluid power cylinders  70  occur simultaneously with the activation of the suction cups  22 , or that the fluid power cylinders  70  may be controlled independently of suction cups  22  to permit the longeron  14  to be clamped at a convenient time after the tool apparatus  10  is secured to the skin member  12 .  
         [0027]    Returning to FIG. 1, and with additional reference to FIGS. 5 and 6, tool  26  is illustrated to be a commercially-available, pneumatically-powered drill motor  90  having a rotatable chuck  92  for rotating a rotary cutting tool, such as a twist drill  94 , and a linear feed mechanism  96  for feeding the rotary cutting tool into longeron  14  and skin member  12 . In the particular embodiment illustrated, tool  26  also includes a vacuum chip removal device  100  which is connected to a source of vacuum pressure  102 . A detailed discussion of vacuum chip removal device  100  is beyond the scope of this disclosure and need not be provided herein. Briefly, dust and chips that are generated by the rotary hole-forming tool are drawn by the source of vacuum pressure through the vacuum chip removal device  100  to a collection device (not shown) where the chips and dust are collected. A suitable vacuum chip removal device  100  is disclosed in commonly assigned co-pending U.S. patent application Ser. No. 09/573,433 entitled “Drill Motor Vacuum Attachment”, the disclosure of which is hereby incorporated by reference as if fully set forth herein.  
         [0028]    Conveyance mechanism  28  is illustrated to include a pair of vertically-oriented rail assemblies  110 , a horizontally-oriented rail assembly  112 , and a linear bushing assembly  114 , each of which is arranged at a right angle relative to the other two. Each of the vertically oriented and horizontally oriented rail assemblies  110  and  112  includes a rail member  120  and slide  122  which is slidably coupled to the rail member  120 . In its most basic form, the slide  122  includes a bushing which is sized to match the rail member  120  such that when the bushing and the rail member  120  are engaged to one another the slide  122  cannot be moved to any substantial degree in a direction which is perpendicular to the longitudinal axis of rail member  120 .  
         [0029]    Slide  122 , however, preferably includes linear bearings  124  which permit the slide  122  to accurately track the position of the rail member  120  while moving thereon with relatively low frictional losses. Rail members  120  and slides  122  that are constructed in this latter manner are well known in the art and commercially available from NSK Corporation and Thompson Industries, Inc. and as such, need not be discussed in further detail. The opposite ends of the rail member  120  that forms a portion of the horizontally-oriented rail assembly  112  are coupled to the slides  122  of the vertically-oriented rail assemblies  110 , thereby permitting the rail member  120  of the horizontally-oriented rail assembly  112  to be selectively positioned at a desired vertical spacing.  
         [0030]    Linear bushing assembly  114  is illustrated in FIG. 6 to include a bushing assembly  130  and a housing  132 . Bushing assembly  130  is fixedly coupled to a collar  136   a  formed onto drill motor  90 . Housing  132  is fixedly coupled to the slide  122  of horizontally-oriented rail assembly  112  and includes a central cavity  138  through which bushing assembly  130  and a portion of drill motor  90  are disposed. Central cavity  138  is sized to slidingly engage bushing assembly  130  thereby permitting drill motor  90  to be moved along the longitudinal axis of central cavity  138  with relatively low frictional losses.  
         [0031]    With additional reference to FIG. 5, conveyance mechanism  28  is also illustrated to include a lock device  140  that is operable in an engaged mode to inhibit relative movement between frame structure  20  and tool  26 , and a disengaged mode to permit relative movement between frame structure  20  and tool  26 . In the particular example provided, lock device  140  is illustrated to include a plurality of pneumatically actuated lock collars  144   a ,  144   b . Each of the lock collars  144   a  is mounted to a slide  122  and is movable along an associated one of the rail members  120  when the lock device  140  is in the disengaged mode and the lock collar  144   a  is vented. Operation of the lock device  140  in the engaged mode wherein pneumatic pressure is applied to the lock collars  144   a  causes the lock collars  144   a  to frictionally engage an associated one of the rail members  120  to inhibit the movement of the associated slide  122 . Lock collar  144   b  is mounted to the distal side of housing  132 , permitting the collar  136   b  of drill motor  90  to be extended or retracted from housing  132  when lock device is in the disengaged mode and lock collar  144   b  is vented. Operation of the lock device  140  in the engaged mode when pneumatic pressure is applied to lock collar  144   b  causes lock collar  144   b  to frictionally engage collar  136   b  to inhibit movement of the drill motor  90  relative to housing  132 .  
         [0032]    To aid in the positioning of drill motor  90  relative to longeron  14  and skin member  12 , tool  26  preferably includes an alignment device  150  for aligning the rotary cutting tool to a predetermined position relative to longeron  14  and/or skin member  12 . In the particular embodiment illustrated, alignment device  150  is an optical sighting device  152  having a sighting portion  154  which the technician employs to align to an alignment position indicative that the drill motor  90  is in the predetermined position. As shown, optical sighting device  152  is a laser pointer device  158  which is fixedly coupled to the slide  122  of horizontally oriented rail assembly  112 . Laser pointer device  158  is battery operated and produces a beam of light  160  which impacts longeron  14  at a point that coincides with the point at which the rotary cutting tool will form a hole.  
         [0033]    In operation, tool apparatus  10  is placed proximate skin member  12  and longeron  14  and suction cups  22  are energized to secure tool apparatus  10  to skin member  12 . Clamp assemblies  24  are employed to exert a clamping force onto the longeron  14  which retains the mating face  50   b  of the longeron  14  in contact with the mating face  50   a  of the skin member  12 . Lock device  140  is placed in the disengaged mode to permit tool  26  to be positioned to a predetermined position for the forming of a hole  170 . Alignment device  150  is employed to position tool relative to an alignment position indicative of the predetermined position at which the hole  170  is to be formed and thereafter lock device  140  is placed in the engaged mode to fix the location of tool  26  relative to frame structure  20 . Tool  26  is next employed to form a hole through longeron  14  and skin member  12 . Those skilled in the art will understand that the portion of the hole  170  that is formed in longeron  14  may be preformed during the formation of longeron  14 , for example as indicated by reference numeral  170   a . Once the hole  170  is completely formed, lock device  140  is placed in the disengaged mode and the tool  26  is then moved to an offset position to provide increased access to the hole  170 . A fastener  174 , such as a rivet, a bolt or a screw, is disposed through the hole  170  and employed to fasten longeron  14  to skin member  12 . Thereafter, tool apparatus  10  is removed.  
         [0034]    While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.

Technology Classification (CPC): 1