Patent Publication Number: US-6662420-B1

Title: Hydraulic installation tool

Description:
FIELD OF THE INVENTION 
     The present invention relates to installation tools for setting pull type fasteners. 
     BACKGROUND OF THE INVENTION 
     Installation tools and related nose assemblies are utilized in conjunction with a hydraulic pressure source for installing multi-pieced fasteners by applying a relative axial pulling force, for example, between a pin or mandrel and a collar or sleeve. A lockbolt or swage type fastener is an example of a multi-piece fastener that has a pin and collar adapted to be set with the relative axial pulling force of an installation tool. A blind type fastener is another example of a multi-piece fastener that has a pin and a sleeve adapted to be set with the relative axial pulling force of an installation tool. With both the lockbolt and blind type fasteners, the pin has an elongated shank provided with a pintail or pull portion having a plurality of pull grooves adapted to be gripped by a plurality of chuck jaws in the nose assembly. In the deactuated condition, the chuck jaws will be normally held open to facilitate insertion of the pintail portion into the aperture defined by the opened chuck jaws as well as ejection after the fastener has been set. During actuation of the tool with the pintail portion located in the nose assembly, the chuck jaws will be moved to a closed condition for engagement with the pull grooves whereby the pull grooves will be gripped by the chuck jaws. 
     A swage anvil member is adapted to engage the collar or sleeve, depending upon the type of fastener, and, upon actuation of the tool and with the chuck jaws gripping the pintail portion of the pin shank, as noted, a relative axial pulling force is then applied between the collar or sleeve and pin of the fastener by way of the relative axial force between the chuck jaws and the anvil. Typically, the pin or mandrel is provided with a weakened portion or breakneck groove which is located on the pin shank between the pull or pintail portion and the remainder of the shank and is adapted to fracture at a preselected axial load, i.e. pin break load, after the fastener has been set. This results in an installed fastener having a generally flush structure with minimal or no pintail protrusion. In certain tools, the severed pintail portion is ejected rearwardly out through the back end of the tool. 
     The magnitude of the pin break load required to fracture the breakneck groove, however, can result in the generation of a reaction load of significant magnitude. The magnitude of pin break load can be especially high with swage type fasteners since the breakneck groove must be of sufficient strength to withstand the high installation loads required for the anvil to swage the collar onto the pin. As a result, in hand held installation tools employing a construction for pass through or rearward ejection, the severed pintail portion could be ejected with a considerable force in the direction of the operator. As a result, it has been a common practice with such tools to utilize a pintail deflector made of an elastomeric material to absorb some of the force of the pintail portion and to deflect the pintail portion away from the operator. 
     In certain aerospace applications, a limited amount of space is provided for fastening workpieces together with a fastener. In such applications or other applications with a limited amount of space, it is necessary for an operator to have a compact installation tool with a minimal center line to edge distance in order for the operator to be able to fasten the workpieces together in these hard to reach locations. Center line to edge distance refers to the distance from the center of the bore of the installation tool that has a nose assembly disposed therein to the top edge of the installation tool. A need exists in the art these types of compact installation tools. 
     Additionally, in areas of limited clearance space, installation tools are typically operated at high pressure. Unfortunately, at high pressure, hydraulic hoses attached to the installation tool become rigid and limit the range of movement that an operator has with the installation tool. At lower pressures, hydraulic hoses are more flexible and extends the range of movement that an operator has with the installation tool. A need exists in the art for compact installation tools that operate at lower pressure to facilitate a greater range of movement with the installation tool. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an installation tool that can be used in applications that provide a limited amount of space to an operator of the tool. 
     It is an additional object of the invention to provide an installation tool that is compact and has a minimal center line to edge distance. 
     It is another object of the invention to provide an installation tool that operates at lower pressures with flexible hydraulic hoses. 
     These and other objects of the invention are achieved by providing a hydraulic installation tool for installing fasteners, that includes a housing having a first portion adapted to receive a drawbar and a second portion adapted to receive a piston, a gland and a retaining ring. The drawbar has a general L-shape, a through bore and a bore. A portion of the drawbar is slidably disposed within the first portion of the housing. The piston has a threaded bore and a portion of the piston is slidably disposed within the second portion of the housing. The gland has a first bore adapted to receive a portion of the piston and the gland is disposed within the second portion of the housing with a portion of the piston passing through the bore of the gland. The gland also has a threaded second bore that is adapted to receive a threaded screw. The retaining ring has a bore and the retaining ring is disposed within the second portion of the housing and threadedly engages the housing with a portion of the piston passing through the bore of the retaining ring. A threaded first screw passes through the bore of the drawbar and threadedly engages the threaded bore of the piston and a threaded second screw passes through the bore of the retaining ring and threadedly engages the threaded second bore of the gland. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view, to enlarged scale, of the installation tool with the installation tool shown in the deactuated condition and with a pintail deflector attached to the installation tool. A control unit and hydraulic pressure source which are operable with the installation tool are generally shown in block form; 
     FIG. 2 is a side sectional view, to enlarged scale, of the housing of the installation tool; 
     FIG. 3 is a side sectional view, to enlarged scale, of the generally L-shaped drawbar of the installation tool; 
     FIG. 4 is a side sectional view, to enlarged scale, of the eccentric piston of the installation tool; 
     FIG. 5 is a side sectional view, to enlarged scale, of the gland of the installation tool; 
     FIG. 6 is an end view, to enlarged scale, of the installation tool of FIG. 1 taken generally in the direction of the Arrow A in FIG. 1; and 
     FIG. 7 is a side sectional view, to enlarged scale, of a nose assembly that may be engaged with the drawbar of the installation tool. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In FIG. 1, an installation tool  10  is displayed that includes a housing  12  that has been machined to receive the components of the installation tool  10 . FIG. 2 shows a cross sectional view of the housing  12 . FIG. 3 displays a generally L-shaped drawbar  14  that has a nose assembly engaging portion  16 , a housing portion  18  that is adapted to be slidably disposed in the housing  12 , a generally perpendicular extending portion  20  relative to the nose assembly engaging portion  16  and housing portion  18  that includes a recess  22  at the rearward end of the drawbar  14  and a stepped bore  24 . A bore  26  extends through the nose assembly engaging portion  16 , housing portion  18 , the perpendicular extending portion  20  and the recess  22 . The nose assembly engaging portion  16  is of a cylindrical construction that has threads  28  disposed on the exterior surface of the drawbar  14  at its forward end. A ring of reduced diameter  30  relative to the nose assembly engaging portion  16  is located adjacent to the threads  28  and a smooth portion  32  is located adjacent to the ring of reduced diameter  30 . A portion of greater diameter than the nose assembly engaging portion  16  that consists of the housing portion  18  is located adjacent to the smooth portion  32 . Extending generally perpendicularly from the housing portion  18  is the perpendicular extending portion  20 . The main features of the perpendicular portion have been previously described. 
     FIG. 4 shows an eccentric piston  34  adapted to have a portion of the piston  34  slidably disposed within the housing  12  of the installation tool  10 . The piston  34  has a forward portion  36 , a middle portion  38  and a rear portion  40 . A recessed bore  42  that is adapted to receive a hex key is provided within the forward portion  36 . The forward portion  36  is generally of a smooth cylindrical construction. Adjacent the forward portion  36  is a middle portion  38  of increased diameter than the forward portion  36 . A recessed groove  44  is disposed within the middle portion  38  that is adapted to receive an O-ring  46 . A back-up ring  48  is located adjacent to the O-ring  46  in the recessed groove  44 . A smooth cylindrical bore  50  extends through the middle portion  38  that is adapted to receive a valve  52 . The valve  52  consists of a pin that has a smooth cylindrical portion that is disposed within the bore  50  and a square portion that acts as a conduit between an in-bound hydraulic fluid port  54  and an out-bound hydraulic fluid port  56  that are in fluid communication with each other. The rear portion  40  of the piston  34  is generally of a smooth cylindrical construction. A threaded bore  58  that is adapted to receive a screw  60  is located within the rear portion  40 . In the forward portion of the housing  12  that slidably supports the piston  34 , an O-ring  62  and a backup ring  64  are disposed within a recess in the housing  12  to facilitate maintaining the hydraulic pressure during use of the installation tool  10 . 
     FIG. 5 displays a gland  66  that has a bore  68 . The bore  68  has a recessed portion  69  that contains an O-ring  70  and a backup ring  72  that facilitate maintaining the hydraulic pressure during use of the installation tool  10 . The gland  66  has a recessed portion  73  in the periphery of the gland  66 . The recessed portion  73  is adapted to receive an O-ring  74  that facilitates maintaining the hydraulic pressure during use of the installation tool  10 . The periphery of the gland  66  also has a smooth rectangular recess  76  that facilitates the removal of hydraulic fluid from the installation tool  10 . The gland  66  keeps the hydraulic fluid contained within the installation tool  10 . The rearward end of the gland  66  has a threaded bore  78  that is adapted to receive a screw  80 . The bore  68  of the gland  66  is adapted to slidably support a portion of the piston  34 . 
     FIG. 6 shows a retaining ring  82  that has threads disposed on the periphery of the retaining ring  82  that is adapted to be threadedly engaged with threads  83  disposed within the rearward end of the housing  12  that is adapted to contain piston  34 . A portion of the piston  34  passes through the retaining ring  82 . 
     One method of assembling the components of the installation tool  10  is as follows. The O-rings  46 ,  62 ,  70  and  74  and back-up rings  48 ,  64  and  72  are disposed within the components of the installation tool  10  as mentioned above. The smooth cylindrical portion of the valve  52  is disposed within the smooth cylindrical bore  50  of the middle portion  38 . The piston  34  is disposed within the portion of the housing  12  that is adapted to slidably support the piston  34 . The gland  66  is inserted within the rearward portion of the housing  12  that is adapted to slidably support the piston  34  such that a portion of rear portion  40  of the piston  34  passes through the bore  68  of the gland  66  and the smooth rectangular recess  76  is located adjacent to the out-bound hydraulic fluid port  56 . The retaining ring  82  is threadedly engaged with the threads  83  disposed within the rearward portion of the housing  12  that is adapted receive the piston  34 . A screw  80  is threadedly engaged with the threaded bore  78  of the gland  66  such that the head of screw  80  engages the retaining ring  82 . The configuration of the screw  80  and the retaining ring  82  avoid having the retaining ring  82  torque off the installation tool  10  during use. The nose assembly portion  16  and housing portion  18  of the generally L-shaped drawbar  14  are disposed within the housing  12  adapted to receive this portion of the drawbar  14 . A screw  60  is provided that passes through the stepped bore  24  and threadedly engages the threaded bore  58  of the piston  34 . The screw  60  is torqued to 17-20 ft. lbs which reduces deflection at the juncture of the drawbar  14  and piston  34  after the breackneck groove of a fastener is fractured with the installation tool  10 . 
     A guard assembly  84  is attached to the rearward portion of the housing  12  with two threaded screws  85  that are threadedly engaged with threaded recesses located in the rearward portion of the housing  12 . The guard assembly  84  is of sufficient length and strength to avoid having an operator expose their fingers to the reciprocating drawbar  14  and screw  60  during use of the installation tool  10 . 
     Additionally, a pintail deflector  86  that has a projection  87  is engaged with the recess  22  in the drawbar  14 . The deflector  86  is constructed of an elastomeric material that can be resiliently, radially expanded for assembly and disassembly relative to the recess  22 . The deflector  86  is curved at the rearward end of the deflector such that severed pintails will engage the rearward end as they are ejected, and avoid contact with the operator of the installation tool  10 . 
     FIG. 7 displays a nose assembly  90  can be generally constructed in a manner known to those skilled in the art and therefore is only briefly described for purposes of simplicity. The nose assembly  90  has a plurality of chuck jaws  92  adapted to grip a pin by the pull grooves of the pin. The chuck jaws  92  are located at the forward end of a unitized chuck jaw assembly  94  which is slidably disposed within a tubular collet assembly  96  which is slidably supported in an anvil housing  98  which terminates at one end in a swage anvil member  100 . The tubular collet assembly  96  has a tubular collet ejector portion  102  at its forward end and female threads at its rearward end. Optionally, the length of the tubular collet assembly  96  can be extended by using a tubular collet extension (not shown). Such an extension would have male threads at its forward end for threadedly engaging the threads of the tubular collet assembly  96  and have female threads at its rearward end. The female threads on either the tubular collet assembly  96  or tubular collet extension are provided in order to be threadedly engaged with male threads  28  of the drawbar  14 . In the embodiment displayed in FIG. 7, a retaining ring  104  is disposed within a circular groove that has been machined into the anvil housing  98 . The retaining ring  104  has a pair of opposed flats  106  that are adapted to be disposed within the installation tool  10 . The nose assembly  90  is affixed to the installation tool  10  in a manner well known in the art. After the nose assembly  90  is affixed to the installation tool  10 , the nose assembly  90  is secured to the installation tool  10  by threadedly engaging a key assembly  107  with a threaded bore disposed in the forward end of the housing  12 . 
     While the installation tool  10 , as shown and described, is specifically configured for the installation of lockbolt or swage type fasteners, features of the present invention can be utilized for tools for installing blind fasteners and other non-swage type fasteners which are installed by the application of a relative axial pulling force. Details of such fasteners have been omitted for purposes of simplicity it being understood that references to pins, collars and portions thereof are of the type well known in the fastener art. 
     A separate hydraulic pressure source  108  is connected to the hydraulic fluid ports  54  and  56  of the installation tool  10  by hydraulic hoses  110  and  112 . A control unit  114  that includes a switch (not shown) is also provided that is connected to the hydraulic pressure source  108  via the hydraulic hoses  110  and  112  that is operable from a supply of electric current through suitable conductors to actuate the supply and removal of hydraulic fluid to the installation tool  10 . In an alternate embodiment, the control unit  114  may be operable from a source of pneumatic energy to actuate the supply and removal of hydraulic fluid to the installation tool  10 . When the switch is depressed, hydraulic fluid is supplied to the installation tool  10 . When the switch is released, hydraulic fluid is removed from the installation tool  10 . When the switch is depressed, hydraulic pressure is supplied to the installation tool  10  that applies a relative axial force through the nose assembly  90  for setting multi-pieced fasteners such as the lockbolt fasteners and swage type fasteners previously mentioned. When the switch is released, hydraulic pressure is removed from the installation tool  10  and the nose assembly  90  releases its grip on the fastener. The hydraulic pressure source  108 , the hydraulic hoses  110  and  112  and the control unit  114  are of constructions known in the art. The details of these components have been omitted for purposes of simplicity. 
     Hydraulic pressure from the hydraulic pressure source  108  is provided through hydraulic fluid that is in fluid communication with the piston  34  through hydraulic hose  110  and hydraulic port  54 . Hydraulic pressure in the installation tool  10  is removed through hydraulic fluid that is in fluid communication with the hydraulic pressure source  108  through valve  52 , smooth rectangular recess  76 , hydraulic port  56  and hydraulic hose  112 . 
     The hydraulic pressure source  108  has a high pressure section for moving the piston  34  along with the drawbar  14  rearwardly in its setting stroke to set the fastener and an intermediate pressure section for returning the piston  34  along with the drawbar  14  forwardly to its original position after the fastener has been installed and a low pressure tank or return section which receives the hydraulic fluid displaced from the portion of the housing  12  that contains the piston  34  during the high pressure setting stroke or the intermediate pressure return stroke. 
     The installation tool  10  will be normally in a deactuated condition. With the switch in a deactuated condition, i.e. when not depressed by the operator, the control unit  114  will condition the hydraulic pressure source  108  to connect port  118  to the return or tank section and the port  120  to the intermediate pressure section which is at a hydraulic pressure higher than that at the return or tank section. In this condition, the rearward end of the housing  12  that contains the piston  34  will be pressurized relative to the forward end of the housing  12  that contains the piston  34  portion of the housing  12  urging the piston  34  to its returned or deactuated position as shown in FIG.  1 . 
     To actuate the installation tool  10 , the operator simply depresses the actuating switch which signals the control unit  114  to condition the hydraulic pressure source  108  to connect the port  118 , and the hydraulic line  110 , to the high pressure section and to connect the port  120  and hydraulic line  112  to the return or tank section. In this condition, the forward end of the housing  12  that contains the piston  34  will be connected to the high hydraulic pressure section while the rearward end of the housing  12  that contains the piston  34  will be connected to return or tank section. 
     In the deactuated condition of installation tool  10 , the chuck jaws  92  are radially separated and in an opened condition. In this condition, the shank of a pin of a swage type fastener can be inserted through the aperture or swage cavity  122  and into the opening defined by the radially separated chuck jaws  92 . Upon actuation of the piston  34  along with the drawbar  14  rearwardly in its pull stroke, the tubular collet assembly  96  is moved rearwardly. As this occurs, the chuck jaws  92  are moved radially inwardly as well. Chuck jaws  92  are moved to their radially closed position in which the chuck jaw teeth now fully grip the similarly shaped grooves on the pull portion of the pin shank of the fastener. With the jaw teeth of chuck jaws  92  gripping the pull grooves of the pin, the adjacent side surfaces of the chuck jaws  92  will be slightly spaced from each other. In this position the chuck jaws  92  will define a generally circular aperture of around 360 degrees. At this time, the swage cavity  122  is engaged with the fastener collar which is located over the shank of the pin. Further movement of the tubular collet assembly  96  and the jaw assembly  94  relative to the swage cavity  122  will result in application of the desired relative axial force whereby the collar will be swaged onto lock grooves on the shank of the pin. Upon the application of additional relative axial force, the pin member will be severed at the breakneck groove. Upon fracture of the pin shank, the resultant shock load will move the jaw assembly  94  axially rearwardly and, at the same time, will resiliently move the chuck jaws  92  to their open condition whereby the severed portion of the pin shank will be released by the chuck jaws  92 . The severed portion of the pin member will then pass through the installation tool  10  via the bore  26  for ejection out at the rearward end. 
     Next, the installation tool  10  is returned to its original, deactuated condition by the operator releasing the actuating switch. In this condition, the control unit  114  conditions the hydraulic pressure source  108  to connect the forward end of the housing that contains the piston  34  to the tank or return section and the rearward end of the housing  12  that contains the piston  34  to the intermediate pressure section. Now, the piston  34  along with the drawbar  14  on its return stroke is moved axially forwardly to its original, axially forward position. As this occurs, the collar ejector member  102  engaged the swaged collar whereby the swaged collar is ejected from the swage cavity  122 . 
     After pin break and with the piston  34  in its fully actuated rearward position at the end of the pull stroke, the high pressure being applied during the pull stroke could increase since the piston  34  is no longer moving. The potentially high pressure that could be built up in the forward end of the housing  12  that contains the piston  34  is relieved by way of the clearance between the flats of the valve  52  and the smooth rectangular recess  76 . In this position, the valve  52  permits high pressure fluid to flow from the forward end of the housing  12  that contains the piston  34  to the rearward end of the housing  12  that contains the piston  34  and thereafter to the tank or return section of the hydraulic pressure source  108 . This reduces the pressure at the forward end of the housing  12  that contains the piston  34  to thereby inhibit damage to the installation tool  10 . 
     In the preferred embodiment of the invention, the installation tool has a one half inch center line to edge distance that permits the installation tool  10  to be used in applications that provide a limited amount of space to the operator of the installation tool  10 . The one half inch centerline to edge distance is achieved by the piston  34  reciprocating in the housing  12  parallel to the reciprocating movement of the drawbar  14 . The installation tool  10  is also of a compact construction which allows the installation tool  10  to be used in areas of limited space. The installation tool  10  has a minimal overall length while maintaining single stroke fastener installation. 
     In operation, the installation tool is typically operated between 5400 to 5700 pounds per square inch. Operating the installation tool  10  at that pressure allows the hydraulic hoses  54  and  56  to remain flexible to extend the range of movement an operator would have using the installation tool  10 . 
     Having described the presently preferred embodiments of the invention, it is to be understood that the invention may be otherwise embodied within various functional equivalents within the scope of the appended claims.