TITLE:  RIVET GUN

Inventor: Wolf-Dieter Keppel, Chicago, IL

Assignee: ABEO LLC.  Omaha, NE

Publication No. 20090031545 Rivet Gun

FIELD OF THE INVENTION

          The present invention generally relates to a field of tools and devices for setting rivets, and more particularly to a rivet gun suitable for setting self-drilling rivets.

ABSTRACT OF THE DISCLOSURE

          A rivet gun for setting a self-drilling rivet in one or more work pieces has a tool body having a handle for gripping, a rotation assembly having a motor attached to an axially adjustable shaft and a chuck to thereby impart rotation to the chuck adapted to grip and rotate the shank of the self-drilling rivet.  A hydraulic assembly having a pull bushing is connected to a piston rod attached to a piston and a retraction assembly having a mandrel clamp and a mandrel clamp ring is connected to a spring guide biased toward the mandrel clamp by a spring to thereby compress the mandrel clamp to grip and retract the shank, set the self-drilling rivet in the work pieces and detach the shank from the self-drilling rivet.

BACKGROUND OF THE INVENTION

          Blind setting rivets are usually set in a work piece using a rivet setting tool or device which may be pneumatically, electrically, or hydraulically powered.  Blind setting rivets typically include a hollow rivet body and a mandrel disposed longitudinally within the hollow rivet body.  The mandrel includes a shank terminating in the head for radially compressing and spreading the rivet body as the mandrel is retracted rearward relative to the rivet body.  The shank includes an area of reduced diameter for allowing the head to detach from the shank upon application of predetermined tinsel force supplied to the shank.  To set a blind setting rivet, the shank of the rivet mandrel is inserted into the rivet gun.  The tubular portion of the hollow rivet body is inserted through a hole formed in the work piece and the rivet gun is activated, retracting the shank rearward relative to the rivet body, causing the head to compress and spread the rivet body to set the rivet.  The shank then separates from the head at the area of reduced diameter and is discarded.  Some examples of self-drilling, blind setting rivets, are described in U. S. Patent Nos. 5,741,099, 5,762,456, 5,915,901, 6,904,831, and 6,796,759. In this manner, a separate pole-drilling step may be eliminated when applying the rivet.  However, because conventional rivet

setting tools do not rotate the mandrel rivet, application of such self-drilling rivets currently require the use of a drill for rotating the rivet mandrel to tap a hole in the work piece.  The rivet setting device may then be used setting the rivet in the work piece and detaching the shank from the rivet.  This use of two separate tools slows application of the rivets, reduces their advantage over non-tapping varieties.

          Consequently, it would be advantageous to provide a rivet gun suitable for setting self-drilling rivets.  The rivet gun should be capable of gripping and turning the mandrel of the rivet in order to turn the self-drilling head of the rivet for tapping a hole in one or more work pieces.

BRIEF SUMMARY OF THE INVENTION

          The present invention is directed to a rivet gun for setting a self-drilling rivet.  In one embodiment of the present invention, a rivet gun for setting a self-drilling rivet having a mandrel with a shank and a self-drilling head, a weakened area of reduced diameter and a hollow rivet body surrounding the mandrel for joining one or more work pieces is disclosed.  The rivet gun includes a tool body having a handle for gripping, a rotation assembly having a motor attached to an axially adjustable shaft, mandrel clamp and a chuck to thereby impart rotation to the chuck adapted to grip and rotate the shank of the self-drilling rivet, and a hydraulic assembly connected to a retraction assembly adapted to first grip and retract the shank to set the self-drilling rivet in the work pieces by compressing and spreading the hollow body with the head and second detach the shank from the head at the weakened area of reduced diameter.  In a preferred embodiment, the rivet gun also has a braking assembly having a brake disk extending radially outward from a drive shaft connected to the rotation assembly and a brake body with a brake pad biased toward a non-braking position by a brake spring and actuatably urged by a piston against the brake disk to thereby brake rotation of the rotation assembly.  A pair of triggers on the handle are mechanically or pneumatically interlocked for operating the rivet gun and to prevent simultaneous operation of both triggers.  The axially adjustable shaft has a drive shaft and a drive shaft coupling being notched to form axially extending cams adapted to mate within and slide relative to similarly shaped slots in the drive shaft.  The retraction assembly also has a mandrel clamp ring circumferentially positioned around the mandrel clamp and connected to a spring guide biased toward the mandrel clamp by a spring to thereby compress the mandrel clamp to grip the shank.  The hydraulic assembly has a piston connected to a piston rod attached to a pull bushing and being hydraulically actuated to retract the pull bushing rearward by communicating hydraulic fluid into a chamber between the piston and seal body to retract the mandrel clamp

rearward.  The rivet gun also has a mandrel collector attached rearward of the tool body and in communication with a mandrel tube extending through the rotation assembly for collecting detached shanks.

          A new method for setting a self-drilling rivet in one or more work pieces is disclosed.  The method includes taking a rivet gun having a motor for rotating a chuck, inserting a shank of the self-drilling rivet into the chuck for gripping the shank, rotating the chuck with an axially adjustable shaft attached to the motor for creating a hole through the work pieces with a self-drilling head of the self-drilling rivet, moving a brake body with brake pads into contact with a brake disk attached to the axially adjustable shaft for braking rotation of the axially adjustable shaft, retracting a piston rearward with a piston rod attached to a pull bushing, and compressing a mandrel clamp with a mandrel clamp ring to grip the shank for setting the self-drilling rivet in the work pieces and detaching the shank from the self-drilling head.  In the preferred form, the method also includes the step of urging the mandrel clamp ring forward against the mandrel clamp with a spring guide biased toward the mandrel clamp by a spring, communicating pressurized hydraulic fluid into a chamber between a seal body and the piston for driving the piston rearward away from the seal body and imparting rearward movement to the pull bushing for retracting the mandrel clamp, and sliding axially extending cams of a drive shaft coupling within and relative to similarly shaped axially extending slots of a drive shaft when retracting or extending the mandrel clamp.

          It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed.  The accompanied drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments of the present invention and together with the general description, serve to explain the principles of the invention. 

BRIEF DESCRIPTION OF THE DRAWINGS

          The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:

          Figure 1 is a side elevation view of the rivet gun according to an exemplary embodiment of the present invention;

          Figure 2A is a sectional plan view of the rivet gun according to an exemplary embodiment of the present invention;

          Figure 2B is an enlarged plan view taken along line 2B-2B of Figure 2A;

          Figure 2C is an enlarged plan view taken along line 2C-2C of Figure 2A;

          Figure 3A is an operational isometric view of the rivet gun in Figure 1 (before brake      opens and drill process starts);

          Figure 3B is a sectional view of the rotational coupler taken along line 3B-3B in Figure 3A;

          Figure 3C is a sectional view of the stroke coupler taken along line 3C-3C in Figure 3A;

          Figure 4 is another operational isometric view of the rivet gun in Figure 1 (rivet is set and hydraulic piston is in the retracted position);

          Figure 5 is an enlarged plan view of the rotation and retracting assemblies shown in Figure 2A;

          Figure 6 is a sectional plan view of another embodiment of the rivet gun according to an exemplary embodiment of the present invention;

          Figure 7A is an operational view of the rivet gun in Figure 6 (air supply connected but no trigger button activated);

          Figure 7B is another operational view of the rivet gun in Figure 6 (air supply connected and drill button activated);

          Figure 7C is still another operational view of the rivet gun in Figure 6 (air supply connected and hydraulic trigger button activated);

          Figure 8A is an enlarged plan view of the rotation and retracking assemblies shown in Figure 6;

          Figure 8B is an enlarged plan view of the hydraulic assembly shown in Figure 6;

          Figure 9A is an enlarged plan view of the brake assembly shown in Figure 6 (brake is closed); and

          Figure 9B is another enlarged plan view of the brake assembly shown in Figure 6 (brake is open).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

          Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanied drawings.

          Referring generally to Figures 1-9B, a rivet gun 100 is described in accordance with an exemplary embodiment of the present invention.  The rivet gun 100 is for setting a self-drilling rivet 102 in a work piece 112.  An exemplary self-drilling rivet 102 includes a hollow rivet body 104 and a mandrel 106 extending longitudinally through the hollow rivet body 104.  The mandrel 106 includes a self-drilling head 108 for forming a hole 114 in the work piece 112 and a shank 110, fixedly connected to the self-drilling head 108 for rotating the self-drilling head 108 and cutting through the work piece 112.  After the self-drilling head 108 has passed through the hole 114 formed in the work piece 112, the hollow rivet body 104 is compressed and spread by the self-drilling head 108 as the mandrel 106 is retracted rearward relative to the hollow rivet body 104.  The rearward tinsel force is applied to the shank 110, which has an area of reduced diameter for allowing the self-drilling head 108 to detach from the shank 110 upon application of a predetermined tinsel force.  Preferably, the predetermined tinsel force applied to the shank 110 causes separation of the self-drilling head 108 from the shank 110 upon sufficient compression and spreading of the hollow rivet body 104.  Self-drilling rivet assemblies of a wide variety are suitable for use with the rivet gun 100 of the present invention.  For example, the self-drilling rivet 102 (see Figure 5) and self-drilling rivet assemblies described in U.S. Patent No. 5,741,009, entitled SELF TAPPING BLIND SETTING RIVET ASSEMBLY, issued April 21, 1998; U.S. Paten No. 5,762,456 entitled SELF TAPPING BLIND SETTING BOLT RIVET ASSEMBLY issued June 9, 1998; U.S. Patent No. 5,915,901 entitled BLIND SETTING RIVET ASSEMBLY issued June 29, 1999; U.S. Patent No. 6,796,759 entitled SELF-POLISHING AND TAPPING RIVET ASSEMBLY issued September 28, 2004; U.S. Patent No. 6,904,831 issued September 28, 2004; U.S. Patent Application Serial No. 11/387,574 entitled BLIND-SETTING CORING RIVET ASSEMBLY filed March 22, 2006; and in U.S. Patent Application Serial No. 11/740,101 entitled SELF-POLISHING AND TAPPING RIVET ASSEMBLY filed April 25, 2007, are suitable for use with the rivet gun 100 of the present invention.  The rivet gun 100 of the present invention may also be suitable for setting conventional nonself-drilling blind setting rivet assemblies.

          The rivet gun 100 has a tool body 101 where the various parts and components of the rivet gun 100 are positioned therein or attached thereto.  The tool body 101 may be a unitary-constructed, molded piece or formed by several separate enclosures.  The rivet gun 100, as is generally appreciated and known for operation,

has a handle 103 for gripping and a pair of triggers 244, 245.  The rivet gun 100 may also have a pressure intensifier 250 in communication with an air input 264 as is customary and known in the art. 

In the preferred embodiment, the tool body 101 of the rivet gun 100 has a front cap 182 threadably attached to enclosure 174 (generally enclosing the chuck bearings).  Enclosure 174 is threadably attached to enclosure 177 (generally enclosing the spring 162 and power pull bushing 140) which is in-turn coupled to enclosure 176 (generally enclosing the hydraulic assembly 119) and enclosure 178 (generally enclosing a flange of the motor) by a bolt.  The front cap 182 and enclosures 174, 177, 176, and 178 are attached to enclosure 184 (generally enclosing the motor 180) by threadably connecting enclosure 178 to enclosure 184.  The mandrel collector 212 is threadably attached to enclosure 184 to form a substantial portion of the tool body 101.  Although the preferred assembly has been described, it should be understood that each of the enclosures may be connected together by way of threads, locking detents, snap fittings, or otherwise.  Similarly, the tool body 101 could be formed as a unitary piece, shell or molding.

          The rivet gun 100 is designed to perform generally the functions of gripping and rotating the shank 110 of the self-drilling rivet 102 and retracting the shank 110 of the self-drilling rivet 102 to set the self-drilling rivet 102 within a work piece 112.  The various parts, components and assemblies to effectuate these functions are discussed in the proceeding paragraphs and characterized in part by a rotation assembly 115, a retraction assembly 117 and a hydraulic assembly 119.

Rotation Assembly

          The rotation assembly 115 is driven by a motor 180.  The motor 180 is preferably an air-driven motor; however, it should be appreciated by those skilled in the art that the motor 180 could also be electrically or hydraulically driven.  The motor 180 is secured within enclosure 184 by back plate 190 and motor flange enclosure 178.  In the preferred embodiment, the back plate 190 is threadably attached to enclosure 184, but may be attached by alternative means, such as screws, snap fits, detents, or otherwise.  A pusher 194 is positioned within the motor clamp 192 and secured to the back plate 190.  In addition to supporting the pusher 194 and motor clamp 192, the back plate 190 supports mandrel tube 214 extending through the center of back plate 190 by whereby detached shanks 110 from the self-drilling rivet 102 are shuttled therethrough into mandrel collector 212.  Also supported by back plate 190 is mandrel tube clamp 188, which supports and locks the mandrel tube 214 in place.  The mandrel tube 214 extends through the back plate 190 (as previously

described), motor 180, brake body 172, brake disk/motor drive shaft 170, outer drive shaft 166, draft shaft coupling 168, drive shaft 164, and mandrel clamp 154.

Connected to the output shaft of the motor 180 is brake disk/motor drive shaft 170.  The output shaft of the motor 180 may be rotatably connected to impart rotation to the brake disk/motor drive shaft 170 by way of a key and keyway (not shown), as is customary for transferring rotation from one shaft to another connected shaft.  A brake body 172 with brake pads 222 is attached to the back plate 190 between the brake disk/motor drive shaft 170 and the back plate 190.  The brake body 172 is permitted to move axially provided by brake pad piston 228 being pneumatically actuated.  The forward axial movement of the brake body 172 is resisted by brake spring 272, which forces the brake body 172 rearward relative to the brake disk/motor drive shaft 170 when brake pad piston 228 is inactive.  Thus, the forward axial movement of the brake body 172 moves brake pads 222 into braking contact with the brake disk/motor drive shaft 170 for braking rotation of the brake disk/motor drive shaft 170.  Operation of the braking assembly 121, shown generally in Figures 9A and 9B, is given cursory introduction here, but will be further explained in greater detail here forward.

Continuing discussion of the rotation assembly 115, the outer drive shaft 166 has a tubular body, where one end is threaded to connect to brake disk/motor drive shaft 170 in the preferred embodiment and the opposite end open and adapted to house drive shaft coupling 168.  The drive shaft coupling 168 has a tubular body with a base.  Several slots are notched out of the tubular body from an end opposite the base toward the base leaving cams between each slot (similar to fingers or prongs if left unsupported by the outer drive shaft 166).  In the preferred form, the cams of the drive shaft coupling 168 are attached to the tubular body by a laser weld.  The tubular body of the outer drive shaft 166 reinforces and supports the drive shaft coupling 168 cams to prevent damage, fatigue or failure in the event the cams experience inordinate torsional forces while imparting rotation to or resisting rotation of the drive shaft 164.  The combination of the outer drive shaft 166 housing drive shaft coupling 168 and the drive shaft 164 are similarly fashioned.  Drive shaft 164 has a tubular body with inner and outer surfaces.  Notched out of the tubular body extending from the outer surface toward, but not through, the inner surface are several slots.  The slots in the drive shaft 164 form another coupling adapted and shaped to receive the cams of the drive shaft coupling 168. The cams of the drive shaft coupling 168 received within slots in the drive shaft 164 impart rotational movement from the outer drive shaft 166 to the drive shaft 164 yet still permit the coupling of drive shaft 164 to translate axially within the drive shaft coupling 168 within the outer drive shaft

166 (See Figure 3C).  Positioned within the drive shaft coupling 168 around mandrel tube 214 is ball bearing 116 for rotatably supporting the drive shaft coupling 168 about the mandrel tube 214.  Also, positioned on the outer circumference of the drive shaft 164 between the piston rod 132 and the drive shaft 164 is bearing 136 for rotatably supporting the drive shaft 164 within the piston rod 132.  Connected to the outer circumference of the piston rod 132 is a double threaded adapter 138.  The double threaded adapter 138 connects power pull bushing 140 to the piston rod 132.  Positioned between the drive shaft 164 and double threaded adapter 138 are a pair of needle thrust bearings 204 which are separated by needle thrust bearing 150.  The needle thrust bearings 204 and 150 rotatably support drive shaft 164.  Connected to the inner circumference of the drive shaft 164 is mandrel clamp 154.  Ball bearing 116 rotatably supports movement of the drive shaft 164 connected to the mandrel clamp 154 about the mandrel tube 214.  Mounted on the outer circumference of the mandrel clamp 154 between the drive shaft 164 and the mandrel clamp 154 is a thrust ball bearing 202.  The thrust ball bearing 202 rotatably supports the mandrel clamp 154.  Resting flush against the thrust ball bearing 202 along the outer circumference of the mandrel clamp 154 is spring chamber guide 160.  A spring cap 142 is secured to the front of the power pull bushing 140 around the outer circumference of the power pull bushing 140 and encloses spring washer 144 between the spring cap 142 and the spring chamber guide 160.  The spring washer 144 biases the spring chamber guide 160 away from the spring cap 142 toward thrust ball bearing 202. 

          Mounted on the outer circumference of the mandrel clamp 154 is a needle roller runner 201.  Also, to rotatably support the mandrel clamp 154 within the mandrel clamp ring 156, drive shaft bearings 158 are positioned along the outer circumference of the mandrel clamp 154.  The drive shaft bearings 158 along with needle roller runner 201 support the rotation of the mandrel clamp 154. 

          Threadably attached to the outer circumference of the mandrel clamp ring 156 is spring chamber guide 160.  Spring chamber guide 160 houses spring 162 between a radially extending flange on the piston rod 132 and the spring chamber guide 160.  Spring 162 biases the spring chamber guide 160 away from the piston rod 132 which in turn biases the mandrel clamp ring 156 against the mandrel clamp 154.  The mating surfaces between the mandrel clamp ring 156 and the mandrel clamp 154 may be angled to impart compression forces to thereby reduce the cross-sectional area of the mandrel clamp 154 (See Figure 3B).

          Also attached along the outer circumference of the mandrel clamp ring 156 is a threaded front bearing adjustment 129B.  The threaded front bearing adjustment

129B has threads along its outer circumference for securing enclosure 174 thereto.  Positioned within the threaded front bearing adjustment 129B is chuck needle thrust bearing 128.  Secured also within the threaded front bearing adjustment 129B adjacent the chuck needle thrust bearing 128 is a front needle bearing runner 129A.  Spaced between the enclosure 174 and front bearing runner 122 is chuck needle roller bearing 126 supported on its opposite ends by front needle bearing runner 129A and a radially extending flange on front bearing runner 122.  A front needle bearing runner 203 is also positioned between the enclosure 174 and chuck needle roller bearing 126 for rotatably supporting the mandrel clamp 154.  Positioned within chuck 118 between chuck cap 120 and a radially extending flange on the chuck 118 and resting adjacent the mandrel clamp 154 are several chuck clamp bodies 200.  The chuck clamp bodies 200 are rotatably supported within the chuck 118 by chuck thrust ball bearing cage 124.  The mandrel clamp 154 has rips 270 for gripping the shank 110 of the self-drilling rivet 102.  A mandrel clamp disk 198 is also positioned behind the front cap 182 between the chuck 118 to help encourage retention of the mandrel 106 shank 110 within the chuck 118 before the chuck clamp bodies 200 within the chuck 118 engage the shank 110 of the self-drilling rivet 102.

          The various components and parts of the rotation assembly 115 have been generally described.  Conceptually, rotation of the motor drive shaft 170 imparts rotation to the mandrel clamp 154 which in turn causes chuck clamp bodies 200 within chuck 118 to engage the shank 110 of the self-drilling rivet 102.  This is accomplished as rotation is imparted from the motor 180 to the brake disk/motor drive shaft 170 which is threadably attached to the outer drive shaft 166.  The motor drive shaft 166 in-turn imparts rotational movement to drive shaft coupling 168 which in-turn rotates drive shaft 164.  Mandrel clamp 154 is threadably received within drive shaft 164 so that rotation of drive shaft 164 causes the mandrel clamp 154 to rotate as well.  Lastly, rotation of the mandrel clamp 154 imparts rotation to the chuck clamp bodies 200 contained within the chuck 118 whereby the chuck clamp bodies 200 move from a larger diameter to a smaller diameter to thereby clamp and rotate the shank 110 of the self-drilling rivet 102. 

Retraction & Hydraulic Assemblies

In addition to the rotation assembly 115, the rivet gun 100 has a retraction assembly 117 for retracting the mandrel 106 rearward relative to the hollow rivet body 104 for compressing and spreading the hollow rivet body 104 using the self-drilling head 108 of the self-drilling rivet 102.  In the preferred embodiment, the retraction assembly 117 works in concert with a hydraulic assembly 119 (See Figure

3C, 8A & 8B), which is pneumatically driven, but may be electrically driven as should be appreciated by those skilled in the art. 

The hydraulic assembly 119 is sealably contained within enclosure 176 by piston lip seal 216, piston rod lip seal 218 and piston lip seal backup ring 220.  An aperture is configured into the enclosure 176 for passing high pressure hydraulic fluid through the enclosure 176 into the hydraulic assembly 119 within a hydraulic oil chamber 268 between piston 130 and piston rod seal body 134.  A pressure intensifier 250, as are well known in the art, may be used to convert compressed air from compressed air supply line 262 (See Figure 7A-7C) into high pressure hydraulic or fluid pressure.  For example, the pressure intensifier 250 may have a pneumatically driven piston 266 sealed inside the pressure intensifier 250 or a tube (not shown) to convert 100 psi air pressure from compressed air supply line 262 (See Figure 7A-7C) into 2,500 psi hydraulic pressure inside the hydraulic oil chamber 268.  Thus, as hydraulic fluid is introduced into the hydraulic oil chamber 268 within the enclosure 176, piston 130 is driven rearward from a position adjacent the piston rod seal body 134 to a position adjacent damper plate 224 (See Figure 3A & 4).  The rearward movement of piston 130 imparts rearward movement to the piston rod 132 (retractably supported by bearing 152) which in-turn imparts rearward movement to drive shaft 164 which is slidably received within drive shaft coupling 168 as axially extending cams (buttressed by the outer drive shaft 166) on drive shaft coupling 168 are adapted to mate within and slide relative to similarly shaped slots in the drive shaft 164, which is rotatably supported in part by bearing 136.  By mating drive shaft coupling 168 to drive shaft 164 in this manner, as previously taught, the drive shaft coupling 168 within outer drive shaft 166 permits axial movement of drive shaft 164 relative the drive shaft coupling 168 within outer drive shaft 166.  Thus, the rotation assembly 115 is capable of imparting rotation to the chuck 118 and extending or retracting in length, as needed, to facilitate rearward movement of the mandrel clamp 154 of the retraction assembly 117.  Because drive shaft 164 is threadably attached to mandrel clamp 154, any rearward axial retraction of the drive shaft 164 by the retraction assembly 117 imparts rearward movement to the mandrel clamp 154.  As the mandrel clamp 154 is retracted rearward, the mandrel clamp ring 156, which is biased forward by spring 162, causes a reduction in the cross-sectional area of the mandrel clamp 154 which in-turn causes rips 270 to clamp down on the shank 110 of the self-drilling rivet 102 (See Figure 3B).  Thus, as mandrel clamp 154 is drawn rearward, in an axial manner, mandrel clamp ring 156 compresses mandrel clamp 154 causing a reduction in the cross-sectional area of the mandrel clamp 154 (as previously described) to maintain a constant compression force on the rips 270 of

mandrel clamp 154.  As mandrel clamp 154 is drawn rearward in an axial manner by the hydraulic assembly 119 the mandrel clamp 154 is resisted by mandrel clamp ring 156.  When the mandrel clamp ring 156 engages mandrel ring 210, it is at this point that the mandrel clamp ring 156 must move rearward with the mandrel clamp 154.  Any movement rearward by the mandrel clamp ring 156 is resisted by spring 162 biased against a radially extending flange on spring chamber guide 160.  The rearward movement of mandrel clamp 154, as previously discussed, causes the rips 270 within the mandrel clamp 154 to grip the shank 110 of the self-drilling rivet 102 whereby a rearward tinsel force applied to the shank 110 by the hydraulic assembly 119 moving the retraction assembly 117 rearward sets the self-drilling rivet 102 in the work piece 112 by compressing and spreading the hollow rivet body 104 and separating the self-drilling head 108 from the shank 110 along an area of reduced diameter in the shank 110. 

The release of hydraulic fluid from the hydraulic oil chamber 268 allows spring 162 to move the spring chamber guide 160 forward in an axial direction.  Releasing hydraulic fluid from the hydraulic oil chamber 268 also causes piston 130 to move from a position adjacent damper plate 224 to a position adjacent piston rod seal body 134 (See Figure 3A), which imparts forward axial movement to the piston rod 132, which in-turn through mechanical connection of the piston rod 132 with the mandrel clamp 154 causes the mandrel clamp 154 to move forward to a position adjacent chuck 118.  The forward axial movement of the mandrel clamp 154 releases the compressive force of the rips 270 on the shank 110 of the self-drilling rivet 102, which detached from the self-drilling head 108 of the self-drilling rivet 102 is forced rearward axially through feeder tube 226 and mandrel tube 214 when a new self-drilling rivet 102 is inserted through the mandrel clamp disk 198 into the chuck 118. 

Braking Assembly

          The braking assembly 121 is shown generally in Figures 9A and 9B.  The braking assembly 121 is contained generally within enclosure 178 where outer drive shaft 166 is rotatably supported by brake needle thrust bearing 206 and brake thrust bearing runner 208.  As previously discussed, outer drive shaft 166 is attached to brake disk/motor drive shaft 170.  In another embodiment, the outer drive shaft 166 and brake disk/motor drive shaft 170 may be a single unitary piece.  In either embodiment, the brake disk/motor drive shaft 170 is rotatably supported in part by bearing 229 held in place by retaining ring 231.   Brake disk/motor drive shaft 170 is attached to and driven by a drive shaft of the motor 180 sealed within enclosure 178 in part by motor gasket 186.  Also positioned within enclosure 178 is a brake body

172.  Brake body 172 may be sealed within the enclosure 178 by O-rings 276 and 274.  Attached to the brake body 172 are one or more brake pads 222.  As shown in Figure 3A and 4, a brake pad piston 228 is positioned behind brake body 172, and when brake pad piston 228 is activated, the brake pad piston 228 forces brake body 172 forward against brake disk/motor drive shaft 170, thereby moving brake pad 222 in contact with brake disk/motor drive shaft 170 to stop the rotation of brake disk/motor drive shaft 170.  Upon disengaging brake pad piston 228, the brake body 172 is urged rearward away from brake disk/motor drive shaft 170 by brake spring 272.  For example, Figure 9A shows the brake pad piston 228 being disengaged and brake pads 222 moved away and separated from brake disk/motor drive shaft 170 by brake spring 272.  Alternatively, Figure 9B shows brake pad 222 in contact with brake disk/motor drive shaft 170 for stopping rotation of brake disk/motor drive shaft 170.

Operation of the Rivet Gun

          Figures 7A-7C illustrate generally operation of the rivet gun 100.  As previously discussed, the rivet gun 100 is preferably configured with an air supply line 262 for communicating pressurized air into the air input 264 of the pressure intensifier 250 as shown in Figure 7A.  For example, Figure 7A shows a hydraulic air valve 252 which air supply line 262 enters.  The hydraulic air valve has a trigger 254, preferably positioned within the handle 103 (shown in Figure 1) of the rivet gun 100.  In Figure 7A, the air supply line 262 is shown connected to the hydraulic air valve 252 and the trigger 254 has not been engaged.  In the non-activated position, compressed air is not permitted to pass from the air supply line 262 through the intensifier line 258 and into the air input 264 of the pressure intensifier 250.  Hydraulic air valve 252 prevents pressurized air from the air supply line 262 from entering into the plug line 256. 

Figure 7A also shows a valve configuration for drill air valve 240.  Similar to hydraulic air valve 252, drill air valve 240 may be positioned in the handle 103 (shown in Figure 1) of the rivet gun 100.  Connected to drill air valve 240 is air supply line 238.  Although air supply line 238 is shown separate from air supply line 262, it should be appreciated by those skilled in the art that both air supply lines 238, 262 could be the same air supply line.  The drill air valve 240 has a trigger 244 which is movable to first and second positions.  Thus, for example, the trigger 244 may be a double-action trigger having a first trigger position 246 and a second trigger position 248.  The first trigger position 246 and the second trigger position 248 controlling the flow of pressurized air from air supply line 238 through drill air valve 240.  Positioned before the first trigger position 246 and the air supply line 238 is an exhaust line 242

for venting pressurized air from the air supply line 238 or any return air from the rivet gun 100.  In Figure 7A, the drill air valve 240 is shown connected to air supply line 238 and the trigger 244 is in the neutral position, meaning that the trigger has not been moved to the first trigger position 246 or the second trigger position 248.  In the neutral position, the trigger 244 permits air from the air supply line 238 to enter but not pass through plug line 230, as indicated by the solid line.  Also, in the non-activated position, trigger 244 permits pressurized air from the air supply line 238 to enter the air brake line 234 as indicated by the solid line.  Pressurized air passing through the air brake line 234 engages brake pad piston 228 which forces brake body 172 with brake pads 222 forward into braking contact with brake disk/motor drive shaft 170 to thereby prevent rotation of brake disk/motor drive shaft 170.  In the non-activated position, pressurized air from the air supply line 238 is not permitted to pass through the air release line 236 as indicated by the dashed line, nor the air motor line 232, as also indicated by the dashed line. 

Figure 7B shows the air supply line 262 and 238 connected to hydraulic air valve 252 and drill air valve 240, respectively.  Figure 7B also shows the drill air valve 240 being activated by depression of trigger 244.  Thus, pressurized air from the brake pad piston 228 is permitted to exit the brake pad piston 228 through air brake line 234 and out exhaust line 242 so that brake spring 272 may disengage brake pads 222 from brake disk/motor drive shaft 170, as shown in Figure 9A.  With the brake pads 222 disengaged from brake disk/motor drive shaft 170, the brake disk/motor drive shaft 170 may be rotated.  To rotate brake disk/motor drive shaft 170, pressurized air from the air supply line 238 is permitted to travel through air motor line 232 for driving the motor 180.  When trigger 244 is activated, pressurized air from the air supply line 238 is not permitted to pass through the air brake line 234 nor the plugged line 230, as indicated by the dashed line.

          Figure 7C shows the air supply line 262 and 238 connected to hydraulic air valve 252 and drill air valve 240, respectively.  In Figure 7C, the trigger 254 to the hydraulic air valve 252 is activated.  In the active position, pressurized air from the air supply line 262 is permitted to pass through the hydraulic air valve 252 into intensifier line 258.  The pressurized air passing through intensifier line 258 enters the pressure intensifier 250 through air input 264.  As previously discussed, the pressure intensifier 250 converts the air pressure from air supply line 262 into hydraulic pressure having several times the magnitude of pressure.  Hydraulic fluid from the pressure intensifier 250 is communicated into the hydraulic oil chamber 268 causing piston 130 to be forced rearward away from piston rod cell body 134 to thereby effectuate retraction of the retraction assembly 117.  When trigger 254 of the

hydraulic air valve 252 is activated, trigger 244 of the drill air valve 240 is not permitted to be activated.  Pressurized air from air supply line 238 is permitted to pass through the drill air valve 240 through air brake line 234 for applying the brake.  In the preferred embodiment of the present invention, hydraulic air valve 262 and drill air valve 240 would be interlinked, whether mechanically or pneumatically, so as to prevent one trigger being activated at the same time as another.  For example, as shown in Figure 7C, when trigger 254 of the hydraulic air valve 252 is activated, trigger 244 of the drill air valve 240 may not be activated to thereby prevent pressurized air from air supply line 238 from passing through the air drill valve 240 into air motor line 232 for engaging motor 180 at the same time when the retraction assembly 117 is being operated.

          It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the present invention or without sacrificing all of its material advantages.

What is claimed is:

1.       A rivet gun for setting a self-drilling rivet having a mandrel with a shank and a self-drilling head, a weakened area of reduced diameter and a hollow rivet body surrounding the mandrel for joining one or more work pieces, the rivet gun comprises:

a tool body having a handle for gripping;

a rotation assembly having a motor attached to an axially adjustable shaft connected to a chuck to impart rotation to the chuck adapted to grip and rotate the shank of the self-drilling rivet;

a hydraulic assembly;

a retraction assembly adapted to grip the shank of the self-drilling rivet; and

the hydraulic assembly connected to the retraction assembly adapted to retract the shank to set the self-drilling rivet in the work pieces and detach the shank from the self-drilling head at the weakened area of reduced diameter.

2.       The rivet gun of claim 1 further comprises a braking assembly having a brake disk extending radially outward from a drive shaft connected to the rotation assembly.

3.       The rivet gun of claim 2 wherein the braking assembly further comprises a brake body with a brake pad biased toward a non-braking position by a brake spring and actuatably urged by a piston against the brake disk to thereby brake rotation of the rotation assembly.

4.       The rivet gun of claim 1 further comprises a pair of triggers on the handle mechanically or pneumatically interlocked for operating the rivet gun and to prevent simultaneous operation of both triggers.

5.       The rivet gun of claim 1 wherein the axially adjustable shaft further comprises a drive shaft and a drive shaft coupling being notched to form axially extending cams adapted to mate within and slide relative to similarly shaped slots in the drive shaft. 

6.       The rivet gun of claim 1 wherein the retraction assembly further comprises a mandrel clamp and a mandrel clamp ring circumferentially positioned around the mandrel clamp and connected to a spring guide biased toward the mandrel clamp by a spring to thereby compress the mandrel clamp to grip the shank.

7.       The rivet gun of claim 1 wherein the hydraulic assembly further comprises a piston connected to a piston rod attached to a pull bushing and being hydraulically

 actuated to retract the pull bushing rearward by communicating pressurized hydraulic fluid into a chamber between the piston and a seal body.

8.       The rivet gun of claim 7 wherein the pull bushing is adapted to retract the mandrel clamp rearward.

9.       The rivet gun of claim 1 further comprising a mandrel collector attached rearward of the tool body and in communication with a mandrel tube extending through the rotation assembly for collecting detached shanks.

10.     A rivet gun for setting a self-drilling rivet in one or more work pieces, the rivet gun comprises:

a tool body having a handle for gripping;

a rotation assembly having a motor attached to an axially adjustable shaft and a chuck to thereby impart rotation to the chuck adapted to grip and rotate the shank of the self-drilling rivet;

a hydraulic assembly having a pull bushing connected to a piston rod attached to a piston, and

a retraction assembly having a mandrel clamp and a mandrel clamp ring connected to a spring guide biased toward the mandrel clamp by a spring to thereby compress the mandrel clamp to grip and retract the shank, set the self-drilling rivet in the work pieces and detach the shank from the self-drilling rivet.

11.     The rivet gun of claim 10 wherein the axially adjustable shaft further comprises a drive shaft and a drive shaft coupling being notched to form axially extending cams adapted to mate within and slide relative to similarly shaped slots in the drive shaft.

12.     The rivet gun of claim 11 wherein the mandrel clamp is connected to the drive shaft.

13.     The rivet gun of claim 12 wherein pressurized hydraulic fluid communicated into a chamber between the piston and a seal body causes rearward movement of the piston, the piston rod and the pull bushing which imparts rearward movement to the mandrel clamp.

14.     The rivet gun of claim 10 wherein the motor is pneumatically or electrically driven.

15.     The rivet gun of claim 10 wherein the chuck further comprises a plurality of clamp bodies adapted to move from a large cross-section to a smaller cross-section for gripping the shank upon rotation of the chuck and/or rotation assembly.

16.     The rivet gun of claim 10 wherein the handle has an air input for communicating compressed air into the rivet gun.

17.     A method for setting a self-drilling rivet in one or more work pieces, the method comprising:

taking a rivet gun having a motor for rotating a chuck;

inserting a shank of the self-drilling rivet into the chuck for gripping the shank;

rotating the chuck with an axially adjustable shaft attached to the motor for creating a hole through the work pieces with a self-drilling head of the self-drilling rivet;

moving a brake body with brake pads into contact with a brake disk attached to the axially adjustable shaft for braking rotation of the axially adjustable shaft;

retracting a piston rearward with a piston rod attached to a pull bushing; and

compressing a mandrel clamp with a mandrel clamp ring to grip the shank for setting the self-drilling rivet in the work pieces and detaching the shank from the self-drilling head.

18.     The method of claim 17 further comprising the step of urging the mandrel clamp ring forward against the mandrel clamp with a spring guide biased toward the mandrel clamp by a spring.

19.     The method of claim 17 further comprising the step of communicating pressurized hydraulic fluid into a chamber between a seal body and the piston for driving the piston rearward away from the seal body and imparting rearward movement to the pull bushing for retracting the mandrel clamp.

20.     The method of claim 17 further comprising the step of sliding axially extending cams of a drive shaft coupling within and relative to similarly shaped axially extending slots of a drive shaft when retracting or extending the mandrel clamp.

21.     A method for setting a self-drilling rivet in one or more work pieces, the method comprising:

taking a rivet gun having a rotation assembly with a motor for imparting rotation to a chuck, a braking assembly for braking rotation of the rotation assembly and a hydraulic assembly for imparting rearward movement to a retraction assembly;

inserting a shank of the self-drilling rivet into the chuck;

running the motor to rotate the chuck and tap a hole in the work pieces with the self-drilling rivet;

activating the braking assembly by moving a brake body with brake pads into contact with a brake disk of the braking assembly;

engaging the hydraulic assembly to move a piston with a piston rod attached to a pull bushing rearward for imparting rearward movement to the mandrel clamp; and

retracting the mandrel clamp for setting the self-drilling rivet in the work pieces and detaching the shank.

22.     The method of claim 21 further comprising the step of pressing a first trigger for disengaging the brake assembly and activating the rotation assembly.

23.     The method of claim 22 further comprising the step of pressing a second trigger for engaging the brake assembly and activating the hydraulic assembly and the retraction assembly.

24.     The method of claim 23 further comprising the step of mechanically or pneumatically interlocking the first trigger and the second trigger to prevent simultaneous operation of both triggers.

25.     The method of claim 21 further comprising the step of rotating the chuck one direction for gripping and rotating the shank with a plurality of clamp bodies and an opposite direction for releasing the plurality of clamp bodies from the shank.

26.     The method of claim 21 further comprising the step of connecting an axially adjustable shaft to the mandrel clamp for retracting the mandrel clamp.

27.     The method of claim 21 further comprising the step of ejecting detached shanks from the self-drilling rivet from the mandrel clamp through a mandrel tube into a mandrel collector behind the motor

Email: DKconsulting@mindspring.com