Abstract:
A method of operating a linear friction welding apparatus includes supporting a first work piece with a first fixture, supporting a second work piece with a second fixture, establishing a load between the first work piece and the second work piece along a press axis with a press assembly while the first fixture and the second fixture are in a fixed position relative to one another, simultaneously moving, with a vibrating assembly spaced apart from the press axis, the first fixture and the second fixture along a single weld axis so that both the first work piece and the second work piece are moved with respect to one another along the single weld axis after establishing the load, and heating at least a portion of the first work piece while simultaneously moving the first fixture and the second fixture under the load.

Description:
[0001]    This application is a divisional application of co-pending U.S. application Ser. No. 14/992,862, filed on Jan. 11, 2016, which is a divisional of U.S. application Ser. No. 14/359,282, filed on May 19, 2014, which issued as U.S. Pat. No. 9,233,501 on Jan. 12, 2016, which is a 35 U.S.C. §371 National Stage Application of PCT/US2012/067886, filed on Dec. 5, 2012, which claims the benefit of U.S. Provisional Patent Application, Ser. No. 61/630,128 filed Dec. 5, 2011, the entirety of which are each incorporated by reference herein. 
     
    
       [0002]    This disclosure relates to an apparatus for linear friction welding, and in particular a linear friction welding apparatus having a vibrating assembly or assemblies, which simultaneously vibrate both work pieces along the weld axis during the weld process. 
       BACKGROUND AND SUMMARY 
       [0003]    Linear friction welding (LFW) is a process of joining two components which may be made from the same or different materials. The LFW process typically involves pressing the two components together under a large amount of force and rapidly vibrating the components with respect to one another to generate friction at the interface between the two components. The pressure and movement generate sufficient heat to cause the material at the interface to plasticize. Once the material at the interface begins to plasticize, the vibration is stopped and an increased force is applied. As the plasticized material of both components cools in this static condition, the components are bonded together and a weld is formed. While LFW is suitable in many applications, heretofore, LFW has not been practical for repair welds. 
         [0004]    The linear friction welding (LFW) apparatus of this disclosure, in various embodiments includes a vibrating assembly or assemblies, which simultaneously vibrates both work pieces along the weld axis during the weld process. In one embodiment of this disclosure, separate vibrating assemblies are used to vibrate each work piece along the weld axis relative to each other. Each vibrating assembly has its own oscillator mechanism with motors and cams that can be moved into and out of phase with that of the other vibrating mechanism to generate the relative movement between the work pieces. In another embodiment of this disclosure, the apparatus includes a vibrating assembly that uses a single oscillator and two sets of rocker arms supporting carriages operatively connected by a linkage mechanism to simultaneously vibrate both work pieces along the weld axis. In each embodiment of the LFW apparatus of this disclosure, each vibrating assembly controls the amplitude and frequency of the oscillation during the weld process, but also almost instantly stops the oscillation with no load on the tooling or work piece. Furthermore, vibrating both work pieces relative to one another provides certain mechanical advantages over simply vibrating a single work piece against a fixed or stationary work piece. 
         [0005]    In one embodiment, a method of operating a linear friction welding apparatus includes supporting a first work piece with a first fixture, supporting a second work piece with a second fixture, establishing a load between the first work piece and the second work piece along a press axis with a press assembly while the first fixture and the second fixture are in a fixed position relative to one another, simultaneously moving, with a vibrating assembly spaced apart from the press axis, the first fixture and the second fixture along a single weld axis so that both the first work piece and the second work piece are moved with respect to one another along the single weld axis after establishing the load, and heating at least a portion of the first work piece while simultaneously moving the first fixture and the second fixture under the load. 
         [0006]    In one or more embodiments, simultaneously moving the first fixture and the second fixture includes moving the first fixture with a first oscillator mechanism operatively connected to the first fixture, and moving the second fixture with a second oscillator mechanism operatively connected to the second fixture. 
         [0007]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes moving the first fixture with an oscillator mechanism operatively connected to the first fixture, and transferring movement of the first fixture to the second fixture through a linkage connected between the first fixture and second fixture, thereby moving the second work piece. 
         [0008]    In one or more embodiments transferring movement of the first fixture to the second fixture includes moving the second fixture in a first direction as the first fixture is moving in a second direction, the second direction opposite to the first direction. 
         [0009]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes moving the first fixture with an oscillator mechanism operatively connected to the first fixture, and transferring movement of the first fixture to the second fixture through at least one hydraulic ram of the press assembly connected between the first fixture and second fixture. 
         [0010]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes pivoting the first fixture using a first component pivotably supporting the first fixture, and pivoting the second fixture using a second component pivotably supporting the second fixture, wherein the first component is fixedly positioned with respect to the press axis, and the second component is movable with respect to the press axis. 
         [0011]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes sliding the first fixture along a first slide extending orthogonally to the press axis, and sliding the second fixture along a second slide extending orthogonally to the press axis. 
         [0012]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes sliding the second slide along a third slide extending parallel to the press axis, and sliding the second slide along a fourth slide extending parallel to the press axis. 
         [0013]    In one or more embodiments simultaneously moving the first fixture and the second fixture includes moving the first fixture with a first oscillator mechanism operatively connected to the first fixture, and moving the second fixture with a second oscillator mechanism operatively connected to the second fixture. 
         [0014]    The apparatus and method of the present disclosure may take form in various systems and components, as well as the arrangement of those systems and components. The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. The drawings are only for purposes of illustrating exemplary embodiments and are not to be construed as limiting the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The drawings illustrate the present disclosure, in which: 
           [0016]      FIG. 1  is a simplified side view of an embodiment of the linear friction welding apparatus of this disclosure; 
           [0017]      FIG. 2  is a simplified side view of a second embodiment of the linear friction welding apparatus of this disclosure; 
           [0018]      FIG. 3  is a partial side view of the linear friction welding apparatus of  FIG. 2 ; 
           [0019]      FIG. 4  is a simplified side view of a third embodiment of the linear friction welding apparatus of this disclosure; and 
           [0020]      FIGS. 5 and 6  are partial side views of the linear friction welding apparatus of  FIG. 4 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    Referring now to the drawings, each embodiment of the linear friction welding (LFW) apparatus of this disclosure includes a vibrating assembly or assemblies, which vibrates both work pieces during the weld process. The vibrating assemblies of each embodiments of the LFW apparatus of this disclosure include an oscillation mechanism that embodies the teachings of the linear friction welding (LFW) apparatus developed by APCI, Inc. in South Bend, Ind. that are described in U.S. Pat. No. 8,070,039 issued on Dec. 6, 2011. The oscillator mechanisms enable the LFW apparatus of this disclosure to control the amplitude, frequency and termination of the weld oscillation, as well as the weld and force pressures during the weld process. For simplicity of explanation herein, the particular components of the oscillation mechanisms, as well as their operation and advantage are not fully illustrated or described herein, but may be inferred by reference to the above identified U.S. patent applications and patents, which are incorporated herein. In certain embodiments, the oscillator mechanism may include a ram configured to vibrate along a welding axis, a cam follower operably connected to the ram, an eccentric including an eccentric outer periphery operably engaged with the cam follower, and an inner periphery, a first power shaft slidingly engaged with the eccentric, and a second power shaft eccentrically engaged with the inner periphery. In other embodiments, the oscillator mechanisms may include a ram configured to vibrate along a welding axis, a first power shaft operably connected to the ram and associated with a first eccentricity, a second power shaft operably connected to the ram and associated with a second eccentricity. The oscillator mechanisms are generally controlled electronically by program instructions, and an electronic controllers that control the phased relationship between the first eccentricity and the second eccentricity such that the ram does not vibrate along the welding axis, establish a first pressure between two components to be welded. The electronic controller also controls the phased relationship such that the ram does not vibrate, and the phased relationship such that the ram vibrates along the welding axis after the first pressure has been established. 
       First Embodiment 
       [0022]      FIG. 1  illustrates an embodiment of the linear friction welding (LFW) apparatus of this disclosure, which is designated as reference number  100 . LFW apparatus  100  includes two mounting fixtures  104  and  106  that securely hold work pieces  10  and  10 ′ during the weld process. Mounting fixtures  102  and  104  may take any suitable form or configuration depending on the size, shape and configuration of the work pieces being welding in any particular application. As shown, fixture  104  rides on slides  105  mounted to frame  102  to facilitate the transverse motion of work piece  10  along the weld axis. Similarly fixture  106  rides on slides  107  to facilitate the transverse motion of work piece  10 ′ along the same weld axis. LFW apparatus  100  includes a press assembly  110  that forcibly moves fixture  106  toward fixture  102  to apply the weld and forging pressures to work pieces  10  and  10 ′ during the welding process. As shown, press assembly  110  includes slides  112  which shiftably support fixture  106  and a hydraulic ram  118 , which drives fixture  106  back and forth along slides  112 . LFW apparatus  100  further includes two vibrating assemblies  120  and  130 . Each vibrating assembly  120  and  130  follows the teachings of the above identified patent applications and patents, and includes drive motors  122  and  132 , oscillators  124  and  134 , and drive arms  126  and  128 , respectively. Drive arm  126  is operatively connected to fixture  104  to vibrate work piece  10 . Drive arm  136  is operatively connected to fixture  106  to vibrate work piece  10 ′. 
         [0023]    In this embodiment of the apparatus of this disclosure, the motors/cams of each vibrating assembly are moved into and out of phase to generate the relative movement between the work pieces. When the motors/cams of vibrating assemblies  120  and  130  are in phase with respect to one another, the relative speed between work pieces  10  and  10 ′ is zero. Bringing the motors/cams of vibrating assembly  120  and  130  out of phase with respect to one another creates relative movement (vibration) between work pieces  10  and  10 ′ at a corresponding amplitude. Those skilled in the art will note that in accordance with the teachings of the above identified patent applications and patents, the use of two vibrating assemblies having two sets of oscillator mechanisms provides certain mechanical advantages. Bringing the motors/cams of vibrating assemblies  120  and  130  back into phase terminates the vibration. The use of two vibrating assemblies having separate sets of motors and cams provides a fourfold mechanical advantage in amplitude and frequency over a single oscillator mechanism than simply vibrating one work piece against a stationary work piece. 
       Second Embodiment 
       [0024]      FIGS. 2 and 3  illustrate another embodiment of the linear friction welding LFW) apparatus, which is designated as reference number  200 . LFW apparatus  200  uses a single oscillator and two sets of rocker arm supported carriages operatively connected by a linkage mechanism to simultaneously vibrate both work pieces  10  and  10 ′ along a single weld axis. The dual sets of rocker arm supported carriages connected by the linkage mechanism generate the relative movement between the work pieces, which provides a mechanical advantage over a single oscillator vibrating assembly. 
         [0025]    As shown, LFW apparatus  200  includes two mounting fixtures  204  and  206  that securely hold work pieces  10  and  10 ′ during the weld process. As with the LFW apparatus  100 , mounting fixtures  204  and  206  may take any suitable form or configuration depending on the size, shape and configuration of the work pieces being welded in any particular application. Fixtures  204  and  206  are operatively connected to vibrating assemblies  220 . Vibrating assembly  220  again follows the teachings of the above identified patent applications and patents. Vibrating assembly  220  includes a pair of carriages  230  and  240 , each shiftably supported by rocker arms  232  and  242 , respectively. Rocker arms  232  are pivotally mounted to frame  202  and rocker arms  242  are pivotally mounted to a sliding platform  214 , which forms part of a press assembly  110 . Press assembly  110  also includes slides  218  upon which platform  214  rides and a hydraulic press  112 , which provides the weld and forge pressures for the welding process. A ram  252  operatively connects oscillator  250  to carriage  230 . Following the teachings of the above identified patent applications and patents, oscillator  250  is driven by various motors, linkages, gears and cam assemblies (not shown). Carriages  230  and  240  are operatively connected by a pair of linkage arms  264 , which transfer the oscillating motion from oscillator  250  to simultaneous vibration in opposite directions to the carriages. As shown, a midpoint  265  of each linkage arm  264  is pivotally connected to an upright  262 . Oscillation of ram  252  raises and lowers carriage  230  while simultaneously lowering and raising carriage  240  thereby providing the relative movement (vibration) between work pieces  10  and  10 ′. 
       Third Embodiment 
       [0026]      FIGS. 4-6  illustrate a third embodiment of the linear friction welding LFW) apparatus, which is designated as reference number  300 . Again, LFW apparatus  300  uses a single oscillator and two sets of rocker arm supported carriages operatively connected by a linkage mechanism to simultaneously vibrate both work pieces  10  and  10 ′ along a single weld axis. The dual sets of rocker arm supported carriages are connected by the linkage mechanism, which generates the relative movement between the work pieces, which provides a mechanical advantage over a single oscillator vibrating assembly. 
         [0027]    As shown, LFW apparatus  300  includes a frame  302 , which supports press assembly  310  and vibrating assembly  320 . Two mounting fixtures  304  and  306  that securely hold work pieces  10  and  10 ′ during the weld process are mounted to carriages  330  and  340 , respectively. As with the LFW apparatus  100 , mounting fixtures  306  and  308  may take any suitable form or configuration depending on the size, shape and configuration of the work pieces being welded in any particular application. 
         [0028]    Vibrating assembly  320  includes a pair of shiftable carriages  330  and  340  shiftably supported by a pair of rocker arms  332  and  342 , respectively. Rocker arms  332  pivotally connect carriage  330  to a sliding upright  301 , which rides along a frame rail  303 . Rocker arms  342  pivotally connect carriage  340  to a stationary upright  308 . Carriages  330  and  340  are connected by hydraulic rams  312 , which forms part of the press assembly  310 . The extensible piston of each rams  312  are pivotally connected to carriage  330  and the casing of rams  312  are pivotally connected to carriage  340 . Rams  312  are also pivotally connected to frame  302  at pivot point  309 . Vibrating assembly  320  also includes oscillator  350  which is driven by two electric drive motors  360  in accordance with the teachings of the above identified patent. Oscillator  250  reciprocates a ram  352  to vibrate carriages  330  and  340 . Again, the linkage mechanism provided by rocker arms  332  and  342 , rams  312  and pivot point  309  allows the transfer of the reciprocation of ram  352  of oscillator  350  simultaneously to both carriages  330  and  340  in opposite directions. 
         [0029]    One skilled in the art will note that the LWF apparatus of this disclosure provides certain mechanical advantages. The use of dual oscillators or linkage mechanism in association with a single oscillator allows greater vibration amplitude without increasing the reciprocation distance of the oscillators rams. Consequently, smaller oscillator components may be employed with reduced power demands and without performance decreases. 
         [0030]    The embodiments of the present disclosure herein described and illustrated are not intended to be exhaustive or to limit the disclosure to the precise form disclosed. They are presented to explain the disclosure so that others skilled in the art might utilize its teachings. The embodiment of the present disclosure may be modified within the scope of the following claims.