Abstract:
A swaging tool includes a generally tubular housing having a first end portion including a port for providing pressurized fluid, a second end portion defining a closed cylinder and an intermediate portion therebetween that includes an elongated aperture through an outer surface of the housing. A single-piece piston is movably located within the housing, and axially extends through the intermediate housing portion such that at least a portion of the piston is visible through the aperture. A fixed jaw unit is located on the second end portion of the housing and a movable jaw unit is removably engageable directly to the piston through the aperture.

Description:
FIELD OF THE INVENTION 
     This invention relates to swaging tools for use in swaging fittings, and more particularly to a swaging tool for swaging axially swaged fittings, to join tubes or pipes. 
     BACKGROUND OF THE INVENTION 
     Swaged fittings have been used for many years to connect tubes and pipes in various types of fluid systems, including those used in the aircraft, marine, petroleum and chemical industries. A tube end is inserted into a fitting, usually in the form of a cylindrical sleeve, and then the fitting is swaged with a swaging tool to produce a fluid-tight connection around the tube. This swaging operation usually is carried out by applying a radial force that radially compresses the fitting and tubing inwardly. The radial force may be applied directly by the swaging tool or indirectly by a specially shaped ring that is moved axially by the swaging tool to apply a radial force to the fitting. The present invention is directed to the latter type of swaging tool designed for use with fittings having axially movable swaging rings. 
     Typical axially swaged fittings comprise a cylindrical sleeve having openings at opposite ends for receiving the ends of two tubes to be connected, with a swaging ring at each end of the sleeve. The outer surface of the sleeve and the inner surface of the swaging ring which contact each other are shaped such that axial movement of the swaging ring over the sleeve applies a radial force to the sleeve and, thus, to the tubes. Although not all fittings employ a sleeve with two swaging rings, the use of two swaging rings is necessary when it is desired, as is often the case, to join two tubes to each other. 
     One type of swaging tool for axially swaged fittings includes a generally cylindrical housing having an inner surface and an outer surface, and a piston that is movable in opposite axial directions within the housing. The piston has a cylindrical outer surface in axial sliding engagement with the inner surface of the housing. The housing has a closed axial end and an open axial end where the open end is threaded and connected to a threaded cap, thereby enclosing the piston within the housing. The cap is connected to a source of hydraulic pressure for selectively moving the piston axially within the housing. A first engaging member is formed on the outer surface of the housing adjacent to the closed end for engaging one of the ring or the sleeve of the fitting to restrain it from axial movement. A second engaging member is formed on the outer surface of the piston for engaging the other one of the ring or the sleeve to move it in an axial direction toward the first engaging member upon movement of the piston toward the closed end of the housing. 
     While the above-described swaging tool works quite well, it does have its disadvantages. In particular, the housing is slotted to accommodate axial movement of the piston and second engaging member, which are integrally formed together, thereby retaining the second engaging member in place. Therefore, additional parts and structural support, such as a support ring to support the threaded end of the housing during swaging and gussets or legs to support the engaging members, are often necessary to maintain the structural integrity of the swaging tool. Additionally, it is not possible to easily modify or interchange the engaging members to accommodate differently sized swaged fittings. 
     Attempts have been made to create swaging tools that include relatively easily interchangeable engaging members. One available type of tool includes an elongated housing having an outer surface and defining an inner cylinder that receives a piston. A screw threaded end closure having a pressure fluid inlet closes the end of the cylinder. A piston is axially movable along only a portion of the bore adjacent a first end thereof, and a bar or guide shaft axially extends from a first end of the piston concentrically through the remaining portion of the bore towards a second end of the housing. A movable jaw unit is removably and slidably received on the guide shaft extending axially from the piston through an elongated aperture formed in the housing, and a fixed jaw unit is mounted to the housing second end in confronting relationship to the movable jaw unit. The junction between the shaft and the piston forms a radially extending load-bearing shoulder to support a portion of the movable jaw. A slide arm mounted to the movable jaw unit extends parallel to the cylinder and engages a longitudinal bearing surface on the outside of the cylinder to counteract deflection of the movable jaw unit during a swaging operation. The location of the slide arm along the outside of the cylinder, however, actually aggravates the deflection problem because it significantly increases the distance between the force generating axis (i.e., the piston axis) and the force application axis (i.e., the fitting axis), which, in turn, increases the bending moment on the movable jaw. In addition, as with the swaging tool described above, the threaded end cap requires occasional tightening and therefore increased maintenance of the tool. Moreover, the slide arm is complex to machine and adds undesired stresses to the movable jaw. Additionally, because the movable jaw is not affixed directly to the piston, the increased axial length of the housing prevents use of the tool in confined spaces. 
     Other types of axial swaging tools include movable jaw units mounted to the piston by a threaded fastener, which itself requires tightening. In addition, the movable jaw unit may include a pad that extends parallel to the cylinder to engage a longitudinal bearing surface on the outside of the cylinder. This pad, like the slide arm described above, increases the bending moment on the movable jaw because it increases the distance between the piston axis and the fitting axis. Another type of removable tool provides a removable jaw unit having a base attached to an annular sleeve for mounting about the outer circumference of a piston. To change the jaw, the entire piston must be disassembled. Moreover, existing tools include large numbers of components, making them complex to assemble and disassemble. Existing tools also require a relatively large retention force in a direction perpendicular to the center axis of the tool to affix the movable jaw in place. However, it has been found that only a small amount of force in a direction perpendicular to the tool center axis is necessary to retain the movable jaw in place. As a result, existing tools having removable or readily replaceable movable jaws are overly complex. 
     Thus, a swaging tool that includes readily interchangeable engaging members is desired that has fewer maintenance requirements, is lighter in weight, is more reliable in service, and also fits within confined spaces. Moreover, a tool is desired that includes sufficient frictional force in a direction perpendicular to the tool axis to locate the interchangeable engaging member in place. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an axial swaging tool having a readily replaceable movable jaw unit that utilizes frictional force to structurally retain the movable jaw in place, thereby providing a swaging tool that is extremely compact, includes fewer components, is simple to operate, and is lightweight. 
     The swaging tool includes a generally tubular housing having a first end portion including a port for providing pressurized fluid, a second end portion defining a closed cylinder and an intermediate portion therebetween that includes an elongated aperture through an outer surface of the housing. A single-piece piston is movably located within the housing, and axially extends through the intermediate housing portion such that at least a portion of the piston is visible through the aperture. A compression spring is interposed between a first end of the piston and the housing second end portion to bias the piston toward the housing first end portion. To maintain the spring in place, the piston first end includes an axial bore sized to receive a portion of the spring. A fixed jaw unit is located on the second end portion of the housing and a movable jaw unit is removably engageable directly to the piston. 
     In one embodiment, the piston includes a reduced external diameter portion axially located between two full diameter portions on the portion of the piston visible through the aperture. The movable jaw includes a base having two radially inwardly extending legs separated by a slot sized to fit about the reduced diameter portion of the piston. The axial length of the reduced diameter portion is slightly larger than the axial thickness of the movable jaw base, such that a tight interference fit is obtained when the base is radially inserted through the aperture to engage the piston reduced diameter portion. The two shoulders formed at the interfaces between the axially separated full diameter portions and the reduced diameter portion provide the required load-bearing support while reducing the bending moment on the movable jaw. 
     In a second embodiment, the piston includes a single radial bore perpendicular to the piston axis on a portion of the piston visible through the aperture. The movable jaw is generally Y-shaped, having a radially extending base leg that is sized to achieve a tight interference fit when inserted within the radial bore. Additionally, the axial bore that receives the compression spring may extend axially through the piston from the piston first end to the radial bore, thereby allowing the compression spring to exert an axial force on the base leg to position and retain the movable jaw. A detent attached to the spring may further frictionally engage a recess formed in the base leg to position and retain the movable jaw in place. 
     The swaging tool of the present invention therefore provides a movable jaw that is readily replaceable upon overcoming a slight frictional interference fit between the piston and the movable jaw or between a detent and the jaw. During assembly of a swaged fitting, however, the movable jaw base is completely supported by the piston itself, such that movement of the piston causes corresponding movement of the movable jaw. Moreover, since the piston itself moves in response to introduction of pressurized fluid, thereby moving the movable jaw directly, and since the movable jaw is attached directly to the piston, frictional losses within the tool are minimized, especially over prior art designs. Assembly of the tool is also simplified by minimizing the number of moving parts. Further, since the number of moving parts is reduced, the potential for frictional losses is minimized, while the size of the tool is likewise minimized. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
     FIG. 1 is a cutaway elevational view of a first embodiment of the axial swaging tool of the present invention. 
     FIG. 2 is an elevational view of the movable jaw of the first embodiment. 
     FIG. 3 is a cutaway elevational view of a second embodiment of the present invention. 
     FIG. 4 is an elevational view of the movable jaw of the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A first embodiment of an axial swaging tool  10  is shown with reference to FIG.  1 . Tool  10  includes a housing  12 , a piston  14 , an end cap  16  including a fixed jaw  18 , and a movable jaw  20  affixed to the piston  14 . 
     Housing  12  is generally tubular in shape, and includes a first end portion  22  that further includes is a port  24  through which pressurized fluid may be introduced into the housing to force the piston in a direction away from the port. End cap  16  is attached to housing  12  at a second housing end portion  26  by any conventional means, including screws, threads, pins and retaining rings. In FIG. 1, a retaining ring  28  serves to hold end cap  16  in place. End cap  16  provides a backstop for a compression spring  30  interposed between housing second end  26  and a second or “dry” (i.e. not in contact with pressurized fluid) end  32  of piston  14  that serves to bias piston  14  toward housing first end  22 . As seen in FIG. 1, piston dry end  32  may include a partial axial bore  34  along centerline A—A sized to accommodate and locate spring  30 . 
     Jaws  18  and  20  are formed in accordance with accepted practice in the art, and may include gussets  36 ,  38 , respectively, that limit deflection of the jaws when performing a swaging operation. Fixed jaw  18  is preferably attached to the exterior surface  40  of housing  12  adjacent second end  26 . If desired, fixed jaw  18  may be formed as part of removable end cap  16 , thereby enabling fixed jaw  18  to be readily replaceable and interchangeable as desired. It should also be understood that end cap  16  may be replaced with a similar cap that includes a second port (not shown) for providing pressurized fluid to housing second end  26  to allow the tool  10  to be used in a reversible manner. However, for the purposes of the following description, the tool  10  will be described as if only one port  24  is available to provide pressurized fluid to move piston  14 . 
     As seen in FIG. 1, piston  14  comprises a single piece sized and shaped to fit within tubular housing  12  with small clearance therebetween. Piston  14  is axially movable within housing  12  along axis A—A, which is typically coaxial with the housing&#39;s cylindrical inner surface  62 , in response to force provided by either spring  30  or pressurized fluid. The piston may also be provided with a radial groove  42  adjacent piston first or “wet” (i.e. in contact with pressurized fluid) end  44  to allow location of a radial seal (not shown) to prevent blowby of pressurized fluid between piston  14  and housing inner surface  62  or to provide a bearing surface for slideable movement of piston  14 , or both. Of course, if a second port were provided at housing second end, then a similar groove would be provided in the piston adjacent the dry end  32 . 
     Piston  14  is also formed so that movable jaw  20  is readily insertable, removable and/or replaceable. To accommodate insertion and removal of movable jaw  20 , housing  12  includes an axially extending aperture  44  of sufficient length to allow axial movement of jaw  20  in response to movement of piston  14 . According to the first embodiment, piston  14  includes at least one reduced external diameter portion  46  axially located between two larger diameter portions  48 ,  50  such that the fall diameter portions transition to the reduced diameter portion abruptly at shoulders  52 ,  54 , respectively. As best seen in FIG. 1, reduced diameter portion  46  has an axial length L slightly larger than the width W of movable jaw  20  so that a slight interference fit exists when jaw  20  is inserted into reduced diameter portion  46 , thereby allowing jaw  20  to be easily removed and replaced when not in use. Moreover, only frictional force is used to retain jaw  20  on reduced diameter portion  46 . However, when jaw  20  is being used in a swaging operation, jaw  20  frictionally contacts at least one of shoulders  52 ,  54 . Accordingly, when piston  14  moves axially, jaw  20  moves with the piston. As the piston moves, shoulders  52 ,  54  support jaw  20  to substantially eliminate undesired flex or torque due to forces exerted upon a fitting (not shown), and also retaining the jaw in place during the swaging operation. 
     In order to fit around piston  14 , movable jaw  20  includes a base  56  (FIG. 2) including a slot  58  of sufficient width W 2  to fit radially over piston reduced diameter portion  46 . Slot  58  also preferably includes a contoured bottom  60  shaped to contact a portion of reduced diameter portion outer surface  46  (see FIG.  1 ). Contoured bottom  60  is shown in FIG. 2 as being semi-circular in shape, which contemplates that piston reduced diameter portion  46  is generally circular in cross-section. However, the cross-section of reduced diameter portion  46  may be any practical shape, and contoured bottom  60  should be shaped for facing contact therewith. 
     A second embodiment of a swage tool  110  is shown in FIGS. 3 and 4. Tool  110  includes similarly numbered parts substantially as described above with reference to FIGS. 1 and 2. However, instead of defining a reduced diameter portion, piston  114  is formed with a substantially uniform radial outer diameter  148 , except for an optional groove  142  to allow location of a radial seal (not shown) to prevent blowby of pressurized fluid between piston  114  and housing inner surface  162  or to provide a bearing surface for slideable movement of piston  114 , or both. 
     Additionally, as seen in FIG. 3, piston  114  is formed with an increased length axial through-bore  134  and a radial through bore  172 . Axial bore  134  is generally concentrically formed about axis A′—A′, such that the bore extends at least part of the length of piston  114 . In the preferred embodiment, bore  134  extends about one-half the length of piston  114  to the point where it intersects with radial bore  172 . 
     As best shown in FIG. 4, movable jaw  120  is formed into a generally Y-shape having a base leg  156 , sized and shaped to be received within radial bore  172 , and an upper fitting seat  174 . Seat  174  is conventionally sized and shaped to receive a fitting to be swaged, and may include gussets  138 , while base leg  156  may be formed into any cross-sectional shape, such as rectangular as shown in FIG.  4 . Of course, the cross-sectional shape and size of radial bore  172  should correspond to the cross-sectional shape and size of leg  156 , since leg  156  is designed to be received within radial bore  172  such that an underside  190  of seat  174  contacts the external surface  148  of piston  114 . Additionally, upper seat  174  may include a shelf  192  that interfits with a correspondingly sized countersunk hole at one end of radial bore  172 . Shelf  192  allows tight fitment between jaw  120  and piston  114 , and also may be used to properly align jaw  120  upon insertion into the piston. Shelf  192  also supports seat  174  to prevent unwanted torquing or rotational movement of seat  174  during a swaging operation. 
     As above, a compression spring  130  is interposed between housing second end  126  and a second end  132  of piston  114  and is located within bore  134 . However, spring  130  may be longer than spring  30  (FIG. 1) so that a larger portion of spring  130  is received in axial bore  134 . Accordingly, axial bore  134  must be radially and axially sized to allow sufficient insertion of the spring. Spring  130  is also used to apply an axial force against base leg  156  to assist in retaining movable jaw  120  in place. To apply the axial force, spring  130  may terminate in a detent  176  that is axially biased by the spring and is received in a corresponding recess  178  formed in the base leg  156 . Detent  176  is axially biased by spring  130  into frictional contact with base leg  156 . The frictional force may be increased as a function of the strength of spring  130 , and may also be increased by contouring the interface between detent  176  and recess  178 . As seen in FIGS. 3 and 4, recess  178  and detent  176  are preferably hemi-spherically shaped, but any shape may be used to achieve the desired frictional interface. As an added advantage, the shape of detent  176  and the force of spring  130  may be sufficiently large that shelf  192  may be eliminated, since the interaction between the detent and recess  178  may also serve to locate and properly position the jaw  120  upon insertion into the piston. 
     In both embodiments, installation or removal of jaw  20 ,  120  only requires that resistance due to only a slight frictional interference fit or due to the detent  176  be overcome. Moreover, the amount of friction exerted between jaw  20 ,  120  and piston  14 ,  114  may be adjusted through tolerances or by increasing the force of spring  130 . In any event, it is not necessary to disassemble any part of tool  10  or  110  to replace or insert the movable jaw. Thus, port  24  need never be exposed, thereby reducing the likelihood of introducing contamination within the tool (or the hydraulic fluid). Additionally, only a small number of components are used to fully support heavy loads. In particular, the jaws  20 ,  120  are completely supported by the pistons  14 ,  114 , and interaction between the jaw and piston is designed to directly transfer the loads therebetween with minimal deflection and frictional losses. Due to the relative simplicity of the design, frictional losses have been found to be reduced by approximately one-half over existing designs. Since losses are reduced, the overall efficiency of the tool is increased, allowing more force to be exerted directly against fittings to be swaged. 
     Also, since the piston is formed as a single large component, it is structurally more able to both exert and accept heavy loads, and has the additional advantage of reducing manufacturing costs over multiple component piston designs. Moreover, because of the one-piece piston, the size of tool  10  or  110  may be reduced over existing designs without affecting its structural stability. 
     Preferred embodiments of the present invention have been disclosed. A person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.