Abstract:
An apparatus and method for separating a pin tool from a shoulder tool, after the pin tool and shoulder tool have become welded together during a friction stir welding operation. In one exemplary embodiment a frame is used to support the shoulder tool. A fluid pressure actuating assembly is used for gradually exerting a force on the pin tool while the shoulder tool is held stationary within the frame. The gradually increasing force gradually breaks the weld and separates the pin tool from the shoulder tool without damaging the pin tool.

Description:
FIELD 
       [0001]    The present disclosure relates to friction stir welding devices and methods, and more particularly to an apparatus and method that enables rapid and easy separation of a friction stir welding pin tool that has become welded to a shoulder tool after a friction stir welding operation. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0003]    In Friction Stir Welding (FSW) applications there are two primary types of FSW tools. One of the most common types of FSW tools is a fixed pin type tool. The FSW pin tool is intimately connected to the FSW shoulder tool, and the two effectively act as a single unit. The single shoulder/pin is the most common of the welding tools. 
         [0004]    The second type of FSW tool is a Retractable Pin Tool (RPT), with two individual tools identified as the pin and shoulder tools. The shoulder tool is a hollow shank with a flat, convex, or concave surface. The shoulder tool has a centered tight tolerance hole (i.e., bore) that is formed through the shank, which allows the pin to pass through the hole in order to obtain required differences in pin length, for such applications as tapered skin welding. The shoulder generally is parallel with the surface when it makes contact, and the pin tool is perpendicular to the work surface. In the case of an RPT, there are two separate pieces that are independent, with clearance between pin and shoulder components. 
         [0005]    When performing a FSW procedure, plasticized material migrates up the pin on both the fixed pin and retractable pin tool surfaces. When the weld path is complete, and the spindle stopped, the material that has migrated between the two tools cools and solidifies, essentially fusing the shoulder tool and the retractable pin tool together. The additional material in between the retractable pin tool and the shoulder tool is difficult to separate because the two tools are powered by separate spindle motors. If the motors start at a different speed the high torque created by the two different motors can easily break an expensive pin tool. 
         [0006]    When manually trying to force the fixed pin tool from its shoulder tool, or the retractable pin tool from its shoulder tool, using hand tools, it is extremely easy to accidentally break the pin tool. The pin tool typically runs several hundred dollars in cost, and thus breakage of pin tools can amount to a significant expense. Breakage also can interfere with continuing operation of a FSR system, and thus negatively affect its overall productivity. 
       SUMMARY 
       [0007]    The present disclosure relates to an apparatus and method for separating a pin tool from a shoulder tool, after the pin tool has become welded to the shoulder tool during a friction stir welding operation. In one exemplary embodiment a frame is used to support the shoulder tool stationary. A fluid pressure actuating assembly is used for gradually exerting a force on the pin tool while the shoulder tool is held stationary within the frame. The gradually increasing force gradually breaks the weld and separates the pin tool from the shoulder tool without damaging the pin tool. 
         [0008]    In various embodiments the pressure actuating assembly includes a fluid pressure generating subsystem that supplies a fluid pressure to a drive component subsystem. The drive component subsystem may be formed by a cylinder having an extendable and retractable piston. The piston may include a sleeve that is adapted to hold a rod, where the rod has a diameter enabling it to fit within a bore of the shoulder tool. The fluid pressure causes an extension of the piston, which causes the rod to come into contact with the pin tool that is welded within the bore of the shoulder tool. The force gradually is increased so that the weld between the shoulder tool and the pin tool is gradually broken without damaging the pin tool. 
         [0009]    In still other embodiments the frame is adapted to hold a bushing, where the bushing is dimensioned to removably accept and hold the shoulder tool. The drive component subsystem may be fixedly supported within the frame in axial alignment with the bushing. The drive component subsystem may further include a sleeve that is held by the piston, with the sleeve adapted to hold a rod that is dimensioned to fit within the bore of the shoulder tool. The generation of fluid pressure by the fluid pressure generating subsystem may be manually controlled by an individual to ensure that the fluid pressure applied to the cylinder is gradually increased, and such that the force applied to the pin tool by the rod is gradually increased to eliminate (or virtually eliminate) the risk of damage to the pin tool as the weld is broken. 
         [0010]    The various embodiments enable a shoulder tool and a pin tool of a retractable shoulder/pin tool assembly to be easily accommodated. Separating the pin tool from its associated shoulder tool without breakage can represent a significant cost savings in a friction stir welding operation. 
         [0011]    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 
         [0012]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0013]      FIG. 1  is a perspective view of one exemplary embodiment of the apparatus of the present disclosure; 
           [0014]      FIG. 2  is an exploded perspective view of various components of the apparatus of  FIG. 1 ; 
           [0015]      FIG. 3  is a plan view of the apparatus of  FIG. 1  but with the movable cover removed and a shoulder tool held within a frame of the apparatus; 
           [0016]      FIG. 4  is a side view of the apparatus of  FIG. 1  but with the cover in its raised position; 
           [0017]      FIG. 5  is an enlarged cross sectional side view of a portion of the apparatus taken in accordance with section line  5 - 5  in  FIG. 3 , with a rod of the apparatus about to be moved into a bore of the shoulder tool to urge a pin tool that is welded inside the bore out from the bore; and 
           [0018]      FIG. 6  illustrates the rod shown in  FIG. 5  having been moved into the bore to of the shoulder tool and having broken the weld between the pin tool and the shoulder tool, and the pin tool being partially ejected from the bore. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0020]    Referring to  FIGS. 1 ,  2  and  3 , there is shown a pin tool removal apparatus  10  in accordance with one exemplary embodiment of the present disclosure. The apparatus  10  is used to break the weld between a pin tool and a shoulder tool of a shoulder/pin tool assembly used in a friction stir welding (FSR) operation without damaging the pin tool. The apparatus  10 , in this exemplary embodiment, includes a frame  12 , a drive component subsystem  14  supported within the frame, and a fluid pressure generating subsystem  16 . The fluid pressure generating subsystem  16  and the drive component subsystem  14  can cooperatively be viewed as a fluid pressure actuating assembly  18 . The fluid pressure generating subsystem  16  applies a pressurized fluid, for example an hydraulic fluid, via a conduit  20  to the drive component subsystem  14 . The drive component subsystem  14  includes a rod  21  that can be used to apply a linear, gradually increasing force to the pin tool positioned within the bore of the shoulder tool, to gradually break the weld between the pin tool and the shoulder tool without damaging the pin tool. 
         [0021]    Referring specifically to  FIGS. 2 and 3 , the frame  12  includes top and bottom frame portions  22  and  24 , and wall portions  26 ,  28  and  30  positioned within spaced apart channels  32 ,  34  and  36  in the frame portions  22  and  24 . The wall portions  26 ,  28  and  30  are secured by fastening elements, for example threaded fastening elements  38  ( FIG. 3 ), that may extend through holes in the top frame portion  22  and into blind threaded holes (not visible) in the bottom frame portion  24 . Wall portion  28  has an aperture  40  that enables a portion of the drive component subsystem  14  to project therethrough. Wall portion  30  includes an aperture  42  that enables a bushing  44  to be positioned therein. 
         [0022]    With further reference to  FIGS. 2 ,  3  and  5 , the fluid pressure generating subsystem  16  forms a pump that includes a manually operated lever  48  ( FIGS. 2 and 3 ) that enables an individual to gradually apply a pressurized fluid through the conduit  20  to the drive component subsystem  14 . One suitable fluid pressure generating subsystem  16  is commercially available from the Enerpac Company of Milwaukee, Wis. The drive component subsystem  14 , in this example, comprises an hydraulic cylinder  50  (also available from the Enerpac Company) having an input  52  coupled to the conduit  20 . The hydraulic cylinder  50  effectively forms an hydraulic ram. The cylinder  50  has a linearly extendable and retractable piston  54  that carries a removable sleeve  56 . The sleeve  56  has a bore  58  that holds the rod  21  removably therein and in axial alignment with the bushing  44 . Wall portion  26  also includes a pair of holes  46  that enable threaded screws  47  to extend therethrough and to engage within threaded bores (not shown) in a portion of the cylinder  50 , to support the cylinder  50  fixedly within the frame  12 . 
         [0023]    Referring further to  FIGS. 2 and 4 , optionally, but preferably, the apparatus  10  includes a cover  60  that is pivotally supported to the frame  12  by a suitable pin or fastener  62 . A separate pin or fastener  64  may be used as a “stop” to engage a notch  60   a  in the cover  60  to maintain the cover  60  in a desired position over the frame  12  when the apparatus  10  is being used. The cover  60  provides an added degree of protection in the event of breakage of the shoulder tool/pin tool assembly during the separation process. 
         [0024]    Referring to  FIGS. 3 ,  4 ,  5  and  6 , a pin tool  70  and a shoulder tool  72  can be seen supported within the frame  12  of the apparatus  10 . With specific reference to  FIG. 5 , the shoulder tool  72  is positioned within a bore  74  of the bushing  44  in axial alignment with the rod  21 . It will be appreciated that the bore  74  of the bushing  44  is sized to accommodate the external diameter of the shoulder tool. The bushing  44  can be easily removed and replaced with a different bushing having a different bore diameter to thus enable the apparatus  10  to be used with different diameter shoulder tools. Similarly, the sleeve  56  can be removed and replaced with a different sleeve having a different internal diameter bore, to thus enable it to be used with a different diameter rod. Thus, it will be appreciated that the apparatus  10  can be easily configured to accommodate a plurality of different shoulder tools and pin tools simply by changing out the bushing  44  and the sleeve  56 . 
         [0025]    In the drawings of  FIGS. 5 and 6 , the pin tool  70  has been welded to an interior wall surface of the bore  76  of the shoulder tool  72  during a previous friction stir welding operation. The apparatus  10  is used to separate the pin tool  70  from the shoulder tool  72  by first positioning the shoulder tool  72  in the bushing  44  within the frame  12 , as shown in  FIGS. 5 and 6 . An individual then manually pumps the lever  48  which applies a pressurized fluid into the cylinder  50  of the drive component subsystem  14 . The pressurized fluid causes the piston  54  to extend, as shown in  FIG. 6 , so that the rod  21  is moved linearly into contact with the pin tool  70 . As further fluid pressure is applied via the lever  48 , the gradually increasing fluid pressure in the cylinder  50  causes a gradually increasing linear force to be applied to the pin tool  70 . The gradually increasing force eventually breaks the weld between the pin tool  70  and the interior wall surface of the bore  76  of the shoulder tool  72 . Once the weld is broken, the lever  48  is released and the pressure within the cylinder  50  is removed. The piston  54  is then retracted and the pin tool  70  can be removed from the shoulder tool  72 . 
         [0026]    It is a significant advantage of the apparatus  10  and method of the present disclosure that the manner in which a controlled, gradual force is applied to the pin tool  70  eliminates, or substantially reduces the chance of breakage of the pin tool during the separation process. It is a further significant advantage that the separation process can be performed relatively quickly, with only limited prior experience in using the apparatus  10 , by an individual. The apparatus  10  can also easily be tailored for use with a variety of shoulder tools of different dimensions. The apparatus  10  further enables a shoulder tool to be quickly, accurately positioned in the apparatus without special tools, and to be quickly and easily removed from the apparatus, also without requiring any special tools or handling procedures. The apparatus  10  is further relatively compact and light in weight, making it easy to transport and use at different locations within a manufacturing environment. 
         [0027]    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.