Automated drill process for two-diameter holes in multi-layer variable thickness composite materials

Abstract

A method of manufacturing a mobile platform. The platform includes a structure and a member assembled to the structure. Further, the member has a first and a second surface with a thickness defined there between that is varied. The method includes leaving the member on the structure. Also, the method includes advancing a tool through the member while on the structure. The tool is stopped before the tool advances into the structure by more than about a first pre-selected tolerance. Also, a mobile platform assembly is provided that includes a structure, a member, and a fastener fastening the structure and member via a hole through the structure and assembly. The hole has a first diameter through the structure and a second diameter through the member, wherein the diameter changes within an acceptable depth range. In another preferred embodiment, a boroscope, adapted for inspecting holes having two diameters, is also provided.

1 . A method of manufacturing a mobile platform, the mobile platform including a structure and a plurality of members assembled to the structure, the members each having a first and a second surface with a thickness defined there between that varies with a location on each member and which varies between members, the method comprising: 
 leaving a member with a varied thickness on the structure in such a manner that the second surface is generally adjacent to the structure;    advancing a tool through the member in a direction generally from the first surface toward the second surface; and    stopping the advance before the tool advances into the structure by more than about a first pre-selected tolerance.    
   
   
       2 . The method according to  claim 1 , the stopping further comprising being after the tool advances to within about a second pre-selected tolerance of the second surface.  
   
   
       3 . The method according to  claim 2 , wherein the first and the second pre-selected tolerances are the same.  
   
   
       4 . The method according to  claim 1 , further comprising inspecting the path of the tool to determine where the tool stopped advancing.  
   
   
       5 . The method according to  claim 4 , the inspecting further comprising using a dial indicator adapted to engage a feature in the member formed by the tool at about the time the tool stopped advancing.  
   
   
       6 . The method according to  claim 4 , the inspecting further comprising using a boroscope to view engage a feature in the member formed by the tool at about the time the tool stopped advancing.  
   
   
       7 . The method according to  claim 6 , the using the boroscope further comprising determining whether the tool stopped before advancing into the structure by more than about the first pre-selected tolerance.  
   
   
       8 . The method according to  claim 1 , wherein the structure is an airframe and the member is a wing skin panel.  
   
   
       9 . The method according to  claim 1 , further comprising receiving the varied thickness.  
   
   
       10 . The method according to  claim 1 , the advancing further comprising using the varied thickness to guide a numerically controlled machine.  
   
   
       11 . The method according to  claim 1 , further comprising drilling a hole through the structure and member.  
   
   
       12 . The method according to  claim 11 , the advancing further comprising a reaming of the hole.  
   
   
       13 . The method according to  claim 12 , further comprising fastening the member to the structure with a fastener placed in the hole, the fastener to have an interference fit with the structure and a clearance with the member when the fastener is in the hole.  
   
   
       14 . The method according to  claim 1 , wherein the structure includes a metallic material and the member includes a composite material.  
   
   
       15 . The method according to  claim 1 , wherein the direction of advance forms an acute angle with respect to an orientation of the second surface.  
   
   
       16 . The method according to  claim 1 , further comprising applying liquid shim to the member, the liquid shim forming at least a portion of the second surface and defining at least a portion of the varied thickness.  
   
   
       17 . The method according to  claim 1 , further comprising applying a sealant to the structure to seal the structure and the member.  
   
   
       18 . The method according to  claim 1 , further comprising changing a parameter associated with the tool while advancing the tool.  
   
   
       19 . An assembly for a mobile platform comprising: 
 a structure;    at least one fastener, and    at least one member, each member having a first and a second surface with a thickness defined there between that varies with a location on each member and which varies between members, the at least one member fastened to the structure by the at least one fastener in such a manner that the second surface is generally adjacent to the structure, the assembly defining at least one hole with a first diameter generally within the structure and a second diameter generally within the member, the second diameter extending to between a first pre-selected tolerance into the structure and to within a second pre-selected tolerance from the second surface into the member.    
   
   
       20 . The assembly according to  claim 19 , wherein the first and the second pre-selected tolerances are the same.  
   
   
       21 . The assembly according to  claim 19 , wherein the structure is an airframe and the member is a wing skin panel. thickness.  
   
   
       22 . The assembly according to  claim 19 , wherein the first diameter causes an interference fit between the structure and the fastener and the second diameter causes a clearance between the member and the fastener.  
   
   
       23 . The assembly according to  claim 19 , wherein the structure includes a metallic material and the member includes a composite material.  
   
   
       24 . The assembly according to  claim 19 , wherein an axis of the hole forms an acute angle with respect to an orientation of the second surface.  
   
   
       25 . The assembly according to  claim 19 , further comprising a liquid shim defining at least a portion of the second surface and defining at least a portion of the varied thickness.  
   
   
       26 . The assembly according to  claim 19 , further comprising a sealant between the structure and the member.  
   
   
       27 . The assembly according to  claim 19 , wherein the extension of the second diameters of the at least one holes defines a standard deviation of less than about 0.0028″ (twenty eight ten thousandths of an inch) in the presence of the varied thicknesses.  
   
   
       28 . The assembly according to  claim 19  wherein the hole is orientated at an acute angle with respect to at least one of the structure and the at least one member.  
   
   
       29 . A boroscope for inspecting assemblies including a structure, at least one fastener, and at least one member, each member having a first and a second surface with a thickness defined there between that varies with a location on each member and which varies between members, the at least one member fastened to the structure by the at least one fastener in such a manner that the second surface is generally adjacent to the structure, the assembly defining at least one hole with a first diameter generally within the structure and a second diameter generally within the member, the second diameter extending to between a first pre-selected tolerance into the structure and to within a second pre-selected tolerance from the second surface into the member, the boroscope comprising: 
 a body including a proximal and a distal end, the distal end adapted to engage the first diameter and the second diameter;    at least one index mark on the body and spaced apart by at least one of the first and second tolerances; and    a mirror positioned in such a manner so as to allow a user to view the at least one index mark and the first and the second diameters if the second diameter extends to between the first pre-selected tolerance into the structure and to within the second pre-selected tolerance from the second surface into the member.