Patent Publication Number: US-9902052-B2

Title: Tooling system and method for removing a damaged or defective bushing

Description:
BACKGROUND 
     1. Field of the Invention 
     The present application relates generally to tooling systems, and more particularly, to a tooling system for removing damaged or defective bushings. 
     2. Description of Related Art 
     Bushings are commonly used and well known in the art for effectively providing a protective barrier between two joining structures. In the aircraft industry, bushings are typically used with rotor masts, wherein the bushings prevent wear on the mast by one or more structures attached thereto. After extensive use, the bushings are replaced, which includes the time consuming process of disassembling the rotor assembly and thereafter setting the rotor mast on a milling machine. Conventional methods exhaust considerable time and effort, resulting in increased aircraft downtime and associated maintenance costs. 
     Referring now to the drawings,  FIG. 1  depicts a side view of a conventional rotary aircraft  101  having a rotary system  103  carried above a fuselage  105 . An aircraft engine (not shown) drives rotary system  103  via a mast  107 .  FIGS. 2-4  depict various views of rotor mast  107 . In  FIGS. 2 and 3 , respective front and top views of mast  107  are shown, while  FIG. 4  depicts a cross-sectional view of mast  107  taken at IV-IV of  FIG. 3 . 
     Mast  107  includes a threaded portion  201  that engages with the engine transmission (not shown) and a flange  203  having a plurality of bores  301  that secure to one or more operably associated structures. In the exemplary embodiment, bores  301  extend through the thickness of the flange and are configured to receive bushings  303 . Bushing  303  have proven to be effective means for preventing wear on the inner surface of the bore  301 . Damage to this surface would result in the entire mast having to be replaced, resulting in significant aircraft downtime and associated costs. 
     Conventional assembly methods include press fitting the bushings  303  within bores  301 . The tight tolerance prevents the bushing from being removed from the bore; the removal process requires extensive machining, generally performed on a lathe, mill, or other suitable machining devices. 
     Although great strides have been made in the above-mentioned process for removing and replacing bushings, considerable shortcomings remain. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a side view of a conventional rotary aircraft; 
         FIG. 2  is simplified front view of a rotary mast of the aircraft of  FIG. 1 ; 
         FIG. 3  is a top view of the rotary mast of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of a bore of the rotary mast of  FIG. 3  taken at IV-IV; 
         FIG. 5  is an oblique disassembled view of a tooling system according to one preferred embodiment of the present application; 
         FIG. 6  is an oblique assembled view of the tooling system of  FIG. 5 ; 
         FIG. 7  is a top view of a flange of an alignment tool of the tooling system of  FIG. 5 ; 
         FIG. 8  is a front view of the tooling system of  FIG. 5  shown within the cross-sectional view of the bore of  FIG. 4 ; 
         FIG. 9  is a top view of the bore of  FIG. 4  having a bushing therein; 
         FIG. 10  is a top view of the bore of  FIG. 4  after machining the bushing according to one preferred method of the present application; 
         FIGS. 11-13  are front views depicting the preferred method of removing the bushing from the bore with a driver tool; and 
         FIGS. 14-16  are front views depicting the preferred method of replacing the bushing with a driver tool. 
     
    
    
     While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrative embodiments of the system and method are provided below. It will of course be appreciated that in the development of any actual embodiment, numerous implementation-specific decisions will be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     As briefly discussed above, it should be understood that bushing  303  protects an inner surface of bore  301 , which if damaged, could result in the entire mast  107  having to be replaced. Thus, precision machining is required when removing the bushing  303  from bore  301  so as to prevent damage to the inner surface. The system and method of the present application overcomes common disadvantages associated with conventional tooling systems for removing bushings. Specifically, one or the unique features includes a portable tooling system, which allows easy and rapid removal of the bushing while the mast remains on the aircraft; this feature greatly reduces downtime and maintenance costs associated with the bushing removal process. 
     In one preferred embodiment, the tooling system includes an alignment tool tailored to fit snugly within an inner cavity  403  of bushing  303 . A cutter tool associated with the alignment tool is utilized to machine a groove on the inner surface of the bushing. Due to the forces exerted on the bushings when assembled, the groove causes the bushing to collapse inwardly, which in turn allows removal of the bushing. The system provides precision machining such that the cutter tool never comes in contact with the inner surface of the bore. Further detailed discussion of these features is provided below and shown in the corresponding figures. 
     Referring now to the remaining drawings, wherein like reference characters identify corresponding or similar elements throughout the several views,  FIGS. 5-7  depict various views of the tooling system  501  according to a preferred embodiment of the present application. In the exemplary embodiments, the tooling system removes bushings from bores associated with a rotor mast; however, it will be appreciated that the features discussed herein can easily be adapted for use with other types of structures having bushings. 
     In  FIGS. 5 and 6 , oblique views of tooling system  501  are shown according to one preferred embodiment. Tooling system  501  comprises an alignment tool  503  configured to fit snugly within the inner cavity  403  of bushing  303 . Alignment tool  503  receives and guides a cutter tool  505  that in turn creates a groove on the inner surface  401  of the bushing  303 . 
     During the removal process, cutter tool  505  travels via a guide  517  running along the longitudinal length of alignment tool  503 . The cutter tool  505  is configured to remove material from the inner surface of bushing  303  while traveling via guide  517 , which in turn forms a groove, e.g., groove  805  (see,  FIG. 8 ) on the inner surface  401  of bushing  303 . The groove causes the bushing to slightly collapse inwardly; sufficient to allow removal of the bushing from the bore. In the exemplary embodiment, alignment tool  503  is provided with four guides; however, it will be appreciated that alternative embodiments could include more of less guides. 
     Alignment tool  503  has a diameter D 2  (see  FIG. 8 ) substantially equal to diameter D 1  of bushing  303 . When assembled, alignment tool  503  fits snugly within the inner cavity  403  of bushing  303  so as to prevent movement therein. In some embodiments, an attachment device, e.g., a C-clamp, can be utilized to secure alignment tool  503  within bushing  303 . 
     A driver system  807 , e.g., a handheld drill, attaches to section  507  of cutter tool  505  and rotates a cutter  509  that creates groove  805  along the inner surface  401  of bushing  303 , The cutter  509  passes through a port  513  extending through a flange  515  of alignment tool  503  and is guided within guide  517 . The guides preferably have a radius that is substantially that same as the outer curvature of the cutter  509  so as to prevent chatter and/or walking during the removal process. Tooling system  501  is further provided with a sleeve  521  that receives section  507  therethrough and configured to maintain relative alignment of cutter  509  during the machining process. 
     It should be appreciated that port  513 , guide  517 , and sleeve  521  are operably associated with one another for guiding cutter tool  505  in a direction relatively parallel with inner surface  401 . This feature enables precision machining of a groove  805  on the inner surface of bushing  303 . In particular, alignment tool prevents chattering and/or walking of cutter  509 , which is a common and destructive problem associated with conventional milling processes for removing these types of bushings. 
       FIG. 7  shows a top view of flange  515 . In the exemplary embodiment, four ports extend through flange  515 , namely, ports  513 ,  701 ,  703 , and  705 . Each port is selectively positioned at different locations relative to the center of flange  515 , as depicted with arrows labeled L 1 , L 2 , L 3 , and L 4 . Each port is also coaxially aligned with a respective guide. In the illustrative embodiment, the locations of each port are selectively positioned at different depths relative to surface  519 . For example, L 4  is furthest from the center of the alignment tool while L 1  is closest. Thus, the corresponding guide associated with port  701  creates the greatest groove depth. This feature provides precision machining, wherein the worker gradually increases the depth of groove  805  on inner surface  401  by utilizing the different ports and associated guides. It should be understood that removing too much material in a single pass could cause chatter and/or walking. For this reason, four ports associated with four guides are utilized in the preferred embodiment. However, it will be appreciated that alternative embodiments could utilizes more or less ports and guides, all depending on the desired application, for example, the material composition of the bushing. 
     In a preferred method of machining groove  805 , the worker initially passes the cutter tool through port  701  to travel along the associated guide furthest from the inner surface  401  of bushing  303 . The first pass removes a small amount of material from the inner surface  401 ; the process is then repeated with the remaining ports/guides until a desired groove depth is created. For example, the next step includes utilizing port  513  and the associated guide. To achieve this feature, the worker simply rotates the alignment tool within the cavity of the bushing until the next guide aligns with the groove, then the process is repeated. 
     Referring to  FIG. 8  in the drawings, a front view of alignment tool  503  and a cross-sectional view of bore  301  are shown. During the machining process, a driver system rotates cutter tool  505  while the worker gradually traverses cutter tool  505  within the guide, resulting in a groove  805  on the inner surface  401  of bushing  303  (see also  FIG. 10 ). 
     Tooling system  501  is further provided with an attachment device  801  that secures alignment tool  503  within bore  301 . In the preferred embodiment, device  801  is a C-clamp; however, alternative embodiments could include similarly suitable devices. Attachment device  801  is provided with an opening  803  that allows debris from bushing  303  to pass therethrough. 
       FIGS. 9 and 10  show top views of bushing  303  in bore  301  prior to and after the machining process.  FIG. 9  shows bushing  303  secured against inner surface  401  of bore  301 , while  FIG. 10  shows the effects of the machining process, specifically, the inward collapse of bushing  303  due to the formation of groove  805 . 
     Referring to  FIGS. 11-13  in the drawings, the process of removing bushing  303  from bore  301  is shown. Tooling system  501  further comprises a driver  1101  and a sleeve press tool  1103  for removing the already collapsed bushing  303  from bore  301 . Sleeve press tool  1103  fits within bushing  303  and driver  1101  fits within tool  1103 . A force is exerted on driver  1101 , i.e., a worker hammering driver  1101  with a mallet, which in turn disengages bushing  303  from bore  301 . In the preferred embodiment, driver  1101  has an outer diameter D 3  and tool  1103  has an outer diameter D 4  which are the same as outer diameter D 4  of bushing  303 . 
     Referring to  FIGS. 14-16  in the drawings, the process of placing a new bushing  1401  within bore  301  is shown. A second driver tool  1403  is utilized to drive new bushing  1401  within bore  301 . The preferred method includes applying heat to bore  301  and to chill bushing  1401 , thus expanding and shrinking the two parts prior to placing bushing  1401  in bore  301 . Tool  1403  includes a portion  1405  adapted to fit within bushing  1401  and having an outer diameter D 6  equal to the inner diameter of bushing  1401 . When assembled, portion  1405  fits snugly within bushing  1401 , as shown in  FIG. 15 . Thereafter, a force is exerted by tool  1403 , which in turn causes bushing  1401  to slide within bore  301 . Tool  1403  has an edge  1407  which comes into contact with surface  1409  of flange  203 , thus stopping tool  1403  when bushing  1401  is in position. 
     It is apparent that a system and method with significant advantages has been described and illustrated. The particular embodiments disclosed above are illustrative only, as the embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. It is therefore evident that the particular embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the description. Although the present embodiments are shown above, they are not limited to just these embodiments, but are amenable to various changes and modifications without departing from the spirit thereof.