Patent Publication Number: US-7914242-B2

Title: Aligning a machine tool with a target location on a structure

Description:
This application is a divisional of application Ser. No. 11/832,269, filed Aug. 1, 2007, status allowed. 
    
    
     FIELD 
     The present disclosure relates generally to machine tooling for the construction and assembly of structures and more particularly (but not exclusively) to aligning a machine tool such as a drill or cutting tool with a target location in a structure. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     In the construction of aircraft, two or more parts may be spliced together to form an airframe section. One part typically is overlaid onto another, and holes may be drilled through the aligned parts to accommodate fasteners. Drilling locations in the parts are typically selected in accordance with nominal design specifications. In some splicing applications, drill jigs may be used to guide a drilling tool to the nominal drilling locations. 
     SUMMARY 
     The present disclosure, in one configuration, is directed to an apparatus for aligning a machine tool with a target location on a structure. The apparatus includes a machine plate positionable on the structure. The plate has a plate bushing that provides a hole through the machine plate. The apparatus also includes a nosepiece for guiding a distal end of the tool through the plate bushing to the target location. The nosepiece has a collet configured to be moved at least partly through and sideward in the plate bushing to center the nosepiece on an element projecting from the structure at the target location. The nosepiece is configured for attachment to the plate bushing to establish a predefined approach angle of the tool relative to the projecting element. 
     In another configuration, the disclosure is directed to a machine assembly including a machine tool and an apparatus for aligning a distal end of the machine tool with a target location on a structure. The apparatus includes a machine plate positionable on the structure and having one or more plate bushings each providing a hole through the machine plate. The apparatus also includes a nosepiece for guiding the tool distal end through the plate bushing to the target location when the plate bushing is placed over the target location. The nosepiece has a housing and a collet attached to and extending distally from the housing. The collet has a distal end configured to pass through the plate bushing. The collet is further configured to be moved radially in the plate bushing to center the nosepiece over an element projecting from the structure at the target location. The housing is configured for attachment to the plate bushing to establish normality of the tool relative to the projecting element. 
     In another implementation, the disclosure is directed to a method of aligning a machine tool with a target location on a structure. A distal end of the machine tool is inserted into a nosepiece for guiding a distal end of the tool. The nosepiece has a housing and a collet attached to and extending distally from the housing. The method includes inserting a distal end of the collet through a plate bushing in a machine plate positioned over an element projecting from the structure at the target location. The collet is moved radially in the plate bushing to center the collet distal end over the element projecting from the structure. The method includes affixing the centered collet distal end to the projecting element, and affixing a distal end of the housing to the plate bushing. 
     In yet another configuration, the disclosure is directed to a machine plate for use with a machine tool. The machine plate has a body including at least one plate bushing having a hole positionable relative to a target location on a structure. The plate bushing includes a rim graspable by a nosepiece through which the machine tool is operable. The plate bushing is configured to allow passage therethrough of a distal end of a collet attached to the nosepiece. The plate bushing is further configured to allow radial movement of the collet therein for centering of the collet over an element projecting from the structure at the target location. The plate bushing is further configured to establish a predefined angle of approach by the machine tool relative to the projecting element when the nosepiece has grasped the rim of the plate bushing. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a cross sectional view of a structure in relation to which an apparatus for aligning a machine tool may be used in accordance with one implementation of the disclosure; 
         FIG. 2  is a top perspective view of a machine plate in accordance with one implementation of the disclosure; 
         FIG. 3  is an exploded side perspective view of a nosepiece and plate bushing in accordance with one implementation of the disclosure; 
         FIG. 4  is a perspective view of a plate bushing in accordance with one implementation of the disclosure; 
         FIG. 5  is a perspective view of a distal end of a nosepiece housing in accordance with one implementation of the disclosure; 
         FIG. 6  is a side view of a nosepiece attached to a plate bushing in accordance with one implementation of the disclosure; 
         FIG. 7  is a longitudinal sectional view of a nosepiece and a plate bushing in accordance with one implementation of the disclosure, the nosepiece shown in an unclamped position; 
         FIG. 8  is a top plan view of a plate bushing centered over a target bushing in accordance with one implementation of the disclosure; 
         FIG. 9  is a side perspective view of a nosepiece in clamped position in accordance with one implementation of the disclosure; 
         FIG. 10  is a flow diagram of aircraft production and service methodology; 
         FIG. 11  is a block diagram of an aircraft; 
         FIG. 12  is a block diagram of an apparatus for aligning a machine tool with a target location on a structure in clamped position in accordance with one implementation of the disclosure; and 
         FIG. 13  is a flow diagram of a method of aligning a machine tool with a target location on a structure in accordance with one implementation of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of an aircraft manufacturing and service method  60  as shown in  FIG. 10  and an aircraft  80  as shown in  FIG. 11 . During pre-production, exemplary method  60  may include specification and design  62  of the aircraft  80  and material procurement  64 . During production, component and subassembly manufacturing  66  and system integration  68  of the aircraft  80  takes place. Thereafter, the aircraft  80  may go through certification and delivery  70  in order to be placed in service  72 . While in service by a customer, the aircraft  80  is scheduled for routine maintenance and service  74  (which may also include modification, reconfiguration, refurbishment, and so on). 
     Each of the processes of method  60  may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of venders, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on. 
     As shown in  FIG. 11 , the aircraft  80  produced by exemplary method  60  may include an airframe  82  with a plurality of systems  84  and an interior  86 . Examples of high-level systems  84  include one or more of a propulsion system  88 , an electrical system  90 , a hydraulic system  92 , and an environmental system  94 . Any number of other systems may be included. Although an aerospace example is shown, the principles of the invention may be applied to other industries, such as the automotive industry. 
     Apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service method  60 . For example, components or subassemblies corresponding to production process  66  may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft  80  is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages  66  and  68 , for example, by substantially expediting assembly of or reducing the cost of an aircraft  80 . Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft  80  is in service, for example and without limitation, to maintenance and service  74 . 
     In various implementations, the present disclosure is directed to methods and apparatus for aligning a machine tool with a target location on a structure. The machine tool may be operable, for example, using an orbital drilling unit or other machining module. Various implementations of the disclosure make it possible to perform machining at a target location that could deviate from a nominal machining location. 
     A block diagram of one configuration of an apparatus for aligning a machine tool with a target location on a structure is indicated generally in  FIG. 12  by reference number  200 . The apparatus  200  includes a machine plate  204  positionable on the structure. The plate has a plate bushing  208  that provides a hole through the machine plate  204 . The apparatus also includes a nosepiece  212  for guiding a distal end of the tool (not shown) through the plate bushing  208  to the target location (not shown). The nosepiece  212  has a collet  216  configured to be moved at least partly through and sideward in the plate bushing  208  to center the nosepiece  212  on an element (not shown) projecting from the structure at the target location. The nosepiece  212  is configured for attachment to the plate bushing  208  to establish a predefined approach angle of the tool relative to the projecting element. 
     It should be noted that the disclosure could be implemented in connection with many types of machines and/or tools, including but not limited to cutting machines and tools and non-orbital drills. Power feed or positive feed drill motors, plasma cutting torches, water jet nozzles, laser drilling and/or marking equipment, hole saws, broaching heads, and/or various types of machining heads could be adapted for use in accordance with the disclosure. Additionally, although various implementations may be described with reference to splicing applications, the disclosure is not so limited. The disclosure can be implemented in many applications in which it may be desirable to center a machine tool over a machining location and to utilize the tool along a specific vector or approach angle relative to that location. 
     An exemplary cross section of a structure in which splicing may be performed is indicated generally in  FIG. 1  by reference number  20 . An orbital drilling unit may be used in accordance with one implementation of the disclosure to drill, e.g., through several aligned parts  24 . The parts  24  may be made of different materials, including but not limited to carbon fiber reinforced plastics, metals, etc. In the present example, drilling is to be performed in a plurality of target locations  28 , one of which is shown in  FIG. 1 . Drilling is to be performed along a path  30  through the parts  24 , beginning at the target location  28 , which is defined by a bushing  32  that lines a hole  36  in an upper splice plate  40 . Such a bushing may be referred to in this disclosure and the claims as a “target bushing”. Thus drilling may be specified to be performed at a nominal location indicated generally by reference number  46 . It should be noted, however, that the nominal drilling location  46  may or may not coincide exactly with the target location  28 , dependent, e.g., on tolerances provided in the nominal drilling specification. A flange  50  of the target bushing  32  projects from an upper surface  54  of the structure  20 . 
     Various configurations of an apparatus for aligning a machine tool with a target location on a structure include a machine plate and a nosepiece, e.g., as shown in  FIGS. 2 and 3 . A target location may be, for example, the target bushing  32  installed in the structure  20 , and various aligning apparatus configurations are described below with reference to the structure  20  and target bushing  32 . It should be noted, however, that various implementations are contemplated in relation to other types of target locations. For example, the presence of a hole is not necessary at a target location for configurations of the apparatus to align a machine tool. Additionally or alternatively, the disclosure could be implemented in relation to elements other than bushings that project from a structural surface, e.g. nail heads, screw heads, etc. Although such projections could be circular and/or spherical, they could have other or additional shapes. 
     One configuration of a machine plate is indicated generally in  FIG. 2  by reference number  100 . One configuration of a nosepiece is indicated generally in  FIG. 3  by reference number  102 . As further described below, the nosepiece  102  may be used to guide a distal end  104  of a machine tool  108  through the machine plate  100  to a target drilling location  28  on the structure  20 . The machine tool  108  is, e.g., a cutting tool operable via an orbital drill unit (not shown in  FIG. 3 ). The terms “proximal” and “distal” are used with reference to a user of the machine tool  108 . 
     Referring now to  FIG. 2 , the machine plate  100  may be positioned on and attached to the structure surface  54 . The machine plate  100  has a body  112  made, for example, of solid aluminum that may be elevated from the surface  54 , e.g., by a plurality of supports  116 . A plurality of plate bushings  120  are mounted in the machine plate body  112  to provide a plurality of holes  118  through the body  112 . Each bushing  120  may be positioned over a corresponding target drilling location on the structure  20 . In the present exemplary configuration, the bushings  120  are configured to establish normality of a machine tool relative to a target location as further described below. In some other configurations, however, plate bushings may be configured to establish an approach angle for a machine tool at other than ninety degrees. It should be noted generally that machine plate configurations of various shapes and having various dimensions and numbers of holes, including configurations having a single hole, are contemplated. 
     In the present configuration, each plate bushing  120  has a distal portion  122  fixedly mounted in the machine plate body  112  and a proximal portion  124  extending above a proximal surface  126  of the machine plate body  112 . A plate bushing  120  may be made, e.g., of hardened tool steel and is shown in greater detail in  FIGS. 3 and 4 . The plate bushing proximal portion  124  has a projecting rim  128  that is graspable by the nosepiece  102  as further described below. In the present configuration, the bushing rim  128  includes a plurality of lobes  130 . 
     Referring now to  FIGS. 3 ,  5 ,  6  and  7 , the nosepiece  102  includes a plurality of substantially concentric components, e.g., a housing  132  having a proximal portion  134  and a distal portion  136 , a collet  138 , a collet clamp  140 , a piston  142  and piston cylinder  144 . The housing  132  may be made from one solid piece of steel, e.g., heat treatable stainless or tool steel. The piston  142  and cylinder  144  may be fabricated, e.g., of stainless steel. 
     In the present configuration and as shown in  FIGS. 4 and 5 , the distal portion  136  of the nosepiece housing  132  is configured to mate with lobes  130  of the plate bushing  120 . Specifically, an end  146  of the distal portion  136  has a hole  148  shaped to fit over the lobes  130  when a user positions the nosepiece relative to the plate bushing  120 . As further described below, a user may cause the nosepiece housing  132  to be locked onto the lobes  130  through slots  152  and to be pressed against a distal surface  150  (shown in  FIG. 7 ) provided by the lobes  130 . 
     Referring now to  FIGS. 3 and 6 , the cutting tool  108  is held by a tool holder  154  configured for attachment to an orbital drill unit  156 . The orbital drill unit  156  and attached cutting tool  108  may be rigidly connected with the nosepiece housing  132  at a plurality of housing flanges  158 , two of which are shown in  FIG. 6 . In various configurations the tool holder  154  provides a standard interface, e.g., a HSK mount and heat shrink tool holder interface, between the tool  108  and the orbital drilling unit  156 . In other configurations in which machining modules other than the present exemplary orbital drill unit are used, other or additional types of tool holder interfaces, e.g., CAT, SK, BT interfaces, may be used. The nosepiece housing  132  includes lateral holes  160  for chip evacuation via an external vacuum system and duct (not shown). 
     A proximal portion  162  of the collet  138  is rigidly fixed to the nosepiece housing  132  through the piston cylinder  144 . As shown in  FIG. 7 , a slotted distal portion  164  of the collet extending from the housing  132  includes a lip  166 . The collet may be made of a single piece of material, e.g., of heat treatable stainless or tool steel. Slots  178  allow the machined diameter of the contacting surface of the lip  166  to contract as the collet clamp  140  slides over the distal portion  164  of the collet. The lip  166  is configured to fit over the protruding flange  50  of the bushing  32 . In other implementations, a collet could be configured to fit over an element of a different type and/or having a different shape projecting from a work piece surface. 
     The nosepiece  102  with integral collet  138  is configured for radial movement in the plate bushing  120  to allow centering of the collet  138  with fixed nosepiece  102  on the target bushing flange  50 . Accordingly, dimensions of the plate bushing  120  are based on dimensions of the target bushing  32  and collet  138 , e.g., as shown in  FIG. 8 .  FIG. 8  is a top plan view of the plate bushing  120  centered over the target bushing  32 . An inner diameter  168  of the plate bushing  120  may be established by adding twice the wall thickness of the collet  138  to an amount of leeway to a diameter  170  of the target bushing flange  50 . For example, where a leeway of 0.050 inches is added to twice the collet wall thickness, the resulting plate bushing inner diameter  168  allows radial displacement of the collet  138  by 0.025 inches from a nominal drill location when the collet  138  is moved in the plate bushing  120  to center the nosepiece  102  on the target bushing flange  50 . Thus, in the present configuration, leeway for radial movement of the collet  138  is a function of the difference in diameters  168  and  170  and the outside dimension of the collet clamp  140  divided by two. 
     An outer diameter  172  of the plate bushing  120  may be, e.g., a standard size used in drill plate fabrication. In the present exemplary configuration, the machine plate  100  and plate supports  116  are fabricated to provide a machine plate height that allows each plate bushing  120  to be at an appropriate height from the work piece surface  54  to ensure sufficient contact by the collet  138  over the target bushing flange  50 . 
     The collet clamp  140  has a distal end  174  configured to be extended over the collet  138  to clamp the collet  138  onto the target bushing flange  50 . The clamp  140  may be made from a highly elastic material, e.g., acetal copolymer. Such material allows the collet  138  to close around a target bushing flange within a predetermined vicinity of, e.g., plus or minus 0.010 inch diametric from, a nominal target bushing flange outside dimension and still substantially close a gap  176  (shown in  FIG. 7 ) between the nosepiece housing, plate bushing  120  and collet clamp  140 . 
     An air hose  180  (shown in  FIG. 6 ) extending from an air pressure/vacuum system (not shown) into the housing  132  pneumatically connects the pressure/vacuum system with a space  182  defined in the piston cylinder  144 . The piston  142  is rigidly attached to the clamp  140  and operable to push the clamp  140  at least partially through the housing  132  to clamp the collet  138  onto the target bushing flange  50  and the housing  132  onto the plate bushing  120 . The housing  132  may be clamped onto the plate bushing  120  and against the lobe distal surface  150  to establish normality of the tool  108  relative to the target bushing flange  50 . 
     A machine assembly that includes the foregoing aligning apparatus may be combined with an orbital drill unit and used in the following manner. A user installs the tool  108  in the tool holder  154  and installs the tool holder  154  in the orbital drill unit  156 . The user then affixes the orbital drill unit to the proximal flanges  158  of the nosepiece housing  132  so that the tool  108  is extendable through the nosepiece  102 . The machine plate  100  is positioned over the structure  20  so that one or more plate bushings  120  are positioned over one or more target drilling locations  28 , e.g., over one or more target bushing flanges  50  projecting from the structure surface  54 . Placement of the machine plate may be in accordance with nominal drilling location specifications. 
     The user inserts the nosepiece  102  into a plate bushing  120  so that distal ends of the collet  138  and clamp  140  extend through the plate bushing  120  toward a target bushing flange  50 . To position the collet lip  166  around the target bushing flange  50 , the user may “float” the drill unit motor, keeping the tool distal end  104  retracted from the plate bushing  120 , and may move the collet  138  longitudinally and/or sideward in the plate bushing until the collet  138  is centered on the bushing flange  50 . To position the nosepiece  102  relative to the plate bushing  120 , the user may rotate the nosepiece, e.g., up to about 60 degrees to mate the nosepiece hole  148  with the lobes  130  of the plate bushing  120 . When the nosepiece and lobes have been mated, the piston  142  can be actuated toward the distal end of the housing  132  to lock the plate bushing lobes  130  into the distal end  146  of the nosepiece housing  132 . It should be noted that unless the collet  138  is positioned over and onto the target bushing flange  50 , the nosepiece  102  cannot be rotated and therefore cannot be locked onto the plate bushing lobes  130 . In such manner, incorrect positioning of the collet onto the flange  50  can be avoided. 
     When the nosepiece  102  has been rotated into position over the plate bushing lobes  130 , the user may activate the clamp  140  by introducing gas or hydraulic pressure, e.g., air from the air pressure system through the air hose  180  into the piston cylinder  144 . Air pressure may be supplied in the piston cylinder at between about 100 and 200 pounds per square inch. In some configurations, air pressure as high as about 400 pounds per square inch could be supplied in the cylinder  144 . The pressure causes the piston  142  to push the clamp  140  distally in the piston cylinder  144 . The clamp  140  closes the collet  138  around the flange  50  of the target bushing  32 , centering the machine tool  108  and drill unit  156  over the target bushing  32 . The clamp also clamps the nosepiece  102  against the plate bushing lobes  130 . The nosepiece is forced against the lobe surface  150 , thereby bringing the machine tool  108  and drill unit  156  into normality with the target bushing  32 . This double clamping action, caused by a single stroke of the piston  142 , restrains the nosepiece  102  and drill unit in the machine plate  100  in six degrees of freedom. The drill unit  156  can then be used to drill through the target bushing  32 . The nosepiece  102  is shown in  FIG. 9  in clamped position. 
     To remove the drill unit and nosepiece  102  from the machine plate  100 , the user activates the air system to create a vacuum in the piston cylinder  144 , thereby causing the piston  142  to withdraw the clamp  140  and allow the nosepiece  102  to be removed from the target bushing flange  50  and plate bushing lobes  130 . It should be noted generally that the clamp  140  could be operated in other or additional ways. For example, manual operation of a collet clamp is contemplated in some implementations. It also should be noted that many different types of grasping mechanisms could be used in place of the rim  128  and lobes  130 . For example, the rim and/or nosepiece distal end could include various contours instead of or in addition to flat surfaces. 
     A flow diagram of a method of aligning a machine tool with a target location on a structure in accordance with one implementation of the disclosure is indicated generally in  FIG. 13  by reference number  300 . In step  304  the distal end of the machine tool is inserted into a nosepiece for guiding a distal end of the tool. The nosepiece has a housing and a collet attached to and extending distally from the housing. In step  308 , a distal end of the collet is inserted through a plate bushing in a machine plate positioned over an element projecting from the structure at the target location. In step  312  the collet is moved radially in the plate bushing to center the collet distal end over the element projecting from the structure. In step  316  the centered collet distal end is affixed to the projecting element. In step  320 , a distal end of the housing is affixed to the plate bushing. 
     The foregoing apparatus and methods make it possible to use nominal specifications to position a drill plate over a work piece and then to perform drilling based on the location of a “landmark” on the underlying structure. Configurations of the machine plate and nosepiece interface make it possible to achieve both concentricity and normality in hole processing. It is possible for drilling to deviate from nominal locations while ensuring that a final hole is processed concentric with a required target location, e.g., an installed bushing. After a one-time installation of a drilling tool in the nosepiece, the drill unit and nosepiece can be inserted into a plurality of plate bushings to drill a plurality of hole locations without having to reinstall the tool in the nosepiece or perform other time consuming steps. 
     A single-acting cylinder provides the force sufficient to close the collet that finds the center of an installed work piece bushing and provides normality and rigidity for an orbital drill unit to process a hole. The center line of a hole is not determined by a drill bushing but rather by the location of an installed bushing or other projecting element on the structure. Using the foregoing apparatus and methods can increase productivity and lower production cycle times to produce high-quality holes. 
     The above aligning apparatus can be used in orbital drilling, the benefits of which can include the ability to obtain a plurality of hole diameters from a single cutter, low cutting forces, high surface-feet-per-minute machining of carbon fiber composite, stainless steel and/or titanium structure, minimal entry and/or exit burr and virtually no composite delamination. A simple interface with an orbital drill motor is provided, along with the ability to quickly locate the centerline of a fastener. The “insert, rotate, and lock” process to be followed by an operator is simple and quick to perform. The process is highly visible to an operator, and since there is a dedicated plate bushing size for each fastener diameter, errors can be reduced or eliminated. 
     While various embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the present disclosure. The examples illustrate the various embodiments and are not intended to limit the present disclosure. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.