Fastener Ammunition For Repeating Propellant Gas Powered Driving Tool

Abstract

Fastener ammunition for a propellant gas powered fastener driving tool having a barrel and a breech mechanism at the breech end of the barrel for initially transporting an ammunition round from an ammunition magazine to firing position, selectively firing the round in firing position to drive a fastener into a workpiece, and finally ejecting the spent cartridge case of the fired round, or the entire round in the event that the round is not fired.

Parent Case Text

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of copending application Ser. No. 665,133, filed Sept. 1, 1967, now U.S. Pat. No. 3,514,026.

Description

Reference is made herein to copending applications Ser. No. 671,910, filed Sept. 1, 1967, and entitled "Sealed Open Chamber Breech Mechanism and Caseless Ammunition Therefor", now U.S. Pat. No. 3,446,113, and Ser. No. 665,136, filed Sept. 1, 1967, and entitled "Semicombustible Ammunition for Open Chamber Breech Mechanism", now U.S. Pat. No. 3,507,219.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to power operated fastener driving tools. The invention relates more particularly to fastener ammunition for a repeating propellant gas powered tool of the type disclosed in the above mentioned patent.

2. Prior Art

My prior Pat. No. 3,514,026 discloses a propellant gas powered fastener driving tool for driving a fastener, such as threaded stud, into a workpiece by propellant gas pressure. This tool has a barrel and a breech mechanism at the rear end of the barrel including a firing chamber which is aligned with and opens forwardly to the bore in the barrel when the chamber is in firing position. The wall of the bore is formed with longitudinal grooves. Fixed to the muzzle end of the barrel is a safety collar having a central opening aligned with the bore and an annular stop shoulder facing rearwardly toward and spaced from the latter barrel end to form an annular recess between the shoulder and barrel. The wall of the collar opening is longitudinally grooved like the barrel except that the collar grooves are angularly displaced from the barrel grooves.

SUMMARY OF THE INVENTION

The present invention provides fastener ammunition for the tool of my prior patent. This fastener ammunition comprises a cartridge case having internal longitudinal grooves and containing a fastener and a propellant charge. The fastener has a rear safety head with radially projecting ribs which engage in the cartridge case grooves, a front shank portion to be driven into a workpiece, and a slender stem joining the shank and head.

When the ammunition is located in firing position in the firing chamber of the tool, the cartridge case grooves are aligned with the grooves in the tool barrel. Accordingly, when the ammunition is fired by ignition of its propellant charge with the safety collar of the tool barrel pressed against a workpiece, the fastener is propelled forwardly from the cartridge case through the barrel, with the fastener ribs engaging in the barrel grooves, to drive the fastener shank into the workpiece. Forward travel of the fastener through the barrel is arrested to limit penetration of the fastener into the workpiece, by engagement of the fastener ribs with the stop shoulder of the safety collar. The tool is removed from the fastener by first rotating the tool to align the grooves of its safety collar with the fastener ribs and then withdrawing the tool rearwardly from the fastener. The rear safety head of the fastener is then removed by snapping the stem which joins the head to the fastener shank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fastener driving tool of the type in which the present fastener ammunition is used;

FIG. 2 is a section taken on line 2--2 in FIG. 1;

FIG. 3 is a transverse section through the breech mechanism of the driving tool in FIG. 1, showing the breech cylinder in firing position;

FIG. 4 is a longitudinal section through the driving tool showing the various parts of the tool in the positions which they occupy when the tool is in its normal inoperative condition;

FIG. 5 is an enlarged view looking in the direction of the arrows on line 5--5 in FIG. 4;

FIG. 6 is an enlarged section taken on line 6--6 in FIG. 4;

FIG. 7 is an enlarged section taken on line 7--7 in FIG. 8;

FIG. 8 is a longitudinal section through the driving tool showing the various parts of the tool in the positions which they occupy when the tool is conditioned for firing;

FIG. 9 is a section taken on line 9--9 in FIG. 8; and

FIG. 10 illustrates a stud which has been driven into a workpiece by the fastener driving tool of FIGS. 1 through 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings illustrate fastener ammunition 10 according to the invention for use in a fastener driving tool 40 of the kind disclosed in my Pat. No. 3,514,026. Ammunition 10 includes a fastener 12, a propellant charge 14 for driving the fastener into a workpiece, and an outer cartridge case 16 which contains the fastener 12 and its propellant charge 14. Mounted in the rear end of the case is a primer 18.

Cartridge case 16 has a generally triangular round shape in transverse cross-section and is constructed of a suitable yieldable, non-combustible material, preferably a non-combustible plastic. Extending longitudinally into the front end of the cartridge case 16 is an opening 20. Fixed within and externally complementing this opening is a sleeve or liner 22 having a central bore 24 opening through its ends. The wall of this bore has a number, in this instance three, of uniformally spaced longitudinal grooves 26. Liner 22 is constructed of a suitable non-combustible material which may comprise the same plastic material as the cartridge case. The liner has a length somewhat less than that of the cartridge case opening 20 and is positioned with its front end flush with the front end of the cartridge case. Accordingly, the rear end of the liner is spaced from the rear end of the cartridge case to define therebetween a chamber for containing the propellant charge 14.

Tool ammunition according to the invention may comprise fasteners of various sizes, types, and shapes, depending upon each particular job application. The particular fastener 12 illustrated is an externally threaded stud including a forward pointed shank 28, an intermediate externally threaded body 30, and a rear safety head 32. The safety head is joined to the stud body by a relatively slender connecting stem 34. The rear safety head 32 has a central cylindrical portion 36 of the same diameter as the threaded stud body 30 and a number of uniformally spaced, radially projecting, longitudinally extending ribs 38. These ribs are equal in number to and slidably engaged in the grooves 26 in the cartridge case liner 22. The stud body 30 and cylindrical safety head portion 36 are sized to fit closely but slidably within the liner bore 24. The stud has the same overall length as and is positioned with its ends flush with the ends of the liner 22. The illustrated fastener driving tool 40 is a stud driver having a barrel 42 containing a bore 44 and mounting forward work engaging means 46, and a breech mechansim 48 at the breech end of the barrel for transporting the present ammunition rounds 10 in succession to and firing each round in firing position at the breech end of the bore. The contained stud 12 of each fired round is propelled, by propellant gas pressure, into the workpiece with which the tool is currently engaged. Breech mechanism 48 includes an ammunition carrier or cylinder 50 containing firing chambers 78 for receiving the ammunition rounds 10 to be fired, and means 52 for driving the carrier in such a way as to successively transport the rounds to firing position. The stud driver is equipped with ammunition storage and infeed means 54 for containing a number of ammunition rounds 10 to be fired and automatically feeding the contained rounds in succession to the ammunition carrier 50. The ammunition storage and infeed means of the illustrated stud driver, for example, comprise two ammunition magazines 56a, 56b each capable of holding several ammunition rounds.

The carrier drive means 52 comprises a coupling 58 between the work engaging means 46 and the ammunition carrier 50. This coupling is arranged in such a way that the carrier is driven through the coupling to transport an ammunition round 10 from the ammunition storage means 54 to firing position in response to pressure of the work engaging means against the workpiece with the axis of the barrel 42 at the proper angle, in this instance normal, relative to the work surface. In the event that the tool is removed from the workpiece without firing, the carrier is again automatically driven through the coupling 58 to eject the unfired round. Subsequent re-engagement of the work engaging means with a workpiece transports the next ammunition round from the storage means to firing position. Accordingly, a live ammunition round is never located in firing position in the stud driver except when the latter is properly engaged with a workpiece. The muzzle end of the barrel 42 is provided with a safety ring or collar 60 which cooperates with the safety head 32 of each fired stud 12 to prevent penetration of the stud completely through a workpiece. As will appear from the ensuing description, the safety head of each stud and the safety collar of the stud driver are uniquely constructed and arranged to accomplish this safety function while permitting rapid and easy separation of the driver from each driven stud.

The work engaging means 46 of the illustrated stud driver 40 includes a safety shield 102 and shield interlock means 104. Safety shield 102 has a hollow, generally cylindrical cup 106 with a cylindrical side wall 108 and a rear end wall 110. The front side of the cup is open. Secured to and projecting axially from the rear side of the rear cup wall 110 is a bearing sleever 112 which slidably receives the stud driver barrel 42. Also secured to the rear cup wall 110 and the bearing sleeve 112, and extending rearwardly from the rear wall in laterally spaced relation to the barrel sleeve is a second bearing sleeve 114. This latter sleeve slidably receives a spindle 116 having a rear shaft 118. Shaft 118 extends rotatably through the front end of the breech frame 62 on the axis 72 of the breech cylinder 50 and is secured at its rear end to the cylinder. Disposed within the forward end of the spindle sleeve 114 is a compression spring 120. This spring acts between the rear safety shield wall 110 and the front end of the spindle 116 to yieldably urge the safety shield 102 forwardly along the barrel 42 to its fully extended position of FIG. 4. Forward spring extension or travel of the shield is limited by engagement of the front end of the barrel sleeve 112 with the rear end of the safety collar 60 on the barrel. The safety shield 102 is retractable rearwardly along the barrel 42 to its fully retracted position of FIG. 8 against the action of the shield spring 120. In its fully retracted position, the annular front end face of the safety collar 60 and the annular front edge of the safety shield are located substantially in a common plane normal to the axis of the barrel.

The safety shield spindle sleeve 114 and the breech cylinder spindle 116 form a part of the cylinder drive coupling 58. This drive coupling further comprises motion translating means for converting axial motion of the safety shield 102 into intermittent, unidirectional rotation of the breech cylinder 50. To this end, the illustrated motion translating means comprises a spring loaded cam follower pin 124 carrier by the spindle sleeve 114. Follower pin 124 is dispoed with its axis normal to the axis of the spindle 116 and slidably engages in a double helix groove 126 formed in the outer surface of the spindle. The follower pin 124 and helix screw 126 are so constructed and arranged that the retraction of the safety shield 102 from its fully extended position to its fully retracted position drives the breech cylinder 50 in the counterclockwise direction in FIG. 3 through an angle equal to one-half the angular spacing between the adjacent cylinder firing chambers 78, in this instance through an angle of 60.degree.. Spring return of the shield to its fully extended position drives the cylinder in the same direction through the same angle. When the safety shield 102 is in its fully extended position of FIG. 4 one firing chamber 78 is located in an infeed position A, wherein the chamber registers with an ammunition infeed opening 80a, the following firing chamber (in the direction of cylinder rotation) is located in an infeed position B, wherein the chamber registers with an ammunition infeed opening 80b, and the third firing chamber is located in an ejection position E, wherein the chamber registers with an ejection opening 82.

Each full retraction stroke of the safety shield 102 rotates a cylinder firing chamber 78 from infeed position B to firing position F, and each full extension stroke of the shield rotates the latter firing chamber from firing position to ejection position E, and the following firing chamber to infeed position B.

Safety shield 102 is retracted by engaging the shield with a workpiece W and the pressing forwardly on the tool. The shield is returned to extended position by its spring 120 when the tool is removed from the workpiece.

The safety shield interlock means 104 prevent retraction of the safety shield 102 to arm the stud driver 40, and thereby prevent firing the driver, unless the tool is pressed against a workpiece with the axis of the barrel 42 normal to the work surface. This eliminates the possibility of firing of the tool with the barrel canted relative to the work surface which might permit ricocheting of the fired stud 12.

It will be recalled that the stud 12 of each present ammunition round 10 has a rear safety head 32 including a cylindrical portion 36 with radially projecting safety ribs 38. These safety ribs slidably engage within the longitudinal grooves 26 in the cartridge case liner 22. The wall of the bore 44 in the stud driver barrel 42 is formed with similar longitudinal grooves 148 which register with the liner grooves 126 of each ammunition round 10 when the latter is located in firing position. These barrel grooves are sized to slidably receive the safety head ribs 38 of each fired stud 12. In this regard, it is significant to note that because of the triangular round shape of the illustrated ammunition, each ammunition round 10 may occupy any one of three different angular positions in the breech cylinder firing chambers 78. That is to say, each round may be positioned in a firing chamber with any one of the three curved sides of the round exposed at the open side of the chamber. The liner grooves 26 and barrel grooves 148 are automatically aligned in each position of the round. Accordingly, when an ammunition round is fired in the present stud driver, its contained stud 12 will be propelled forwardly through the bore 44 in such a way that the safety head ribs 38 of the stud engage in and slide along the barrel grooves 148.

Under normal conditions, each fired stud 12 will penetrate the workpiece W until the forward end of the threaded stud body 30 engages the work surface. In this regard, it should be noted a significant feature of the present stud driver ammunition resides in the fact that each ammunition round 10 will contain the proper propellant charge 14 for its particular stud size and type and the particular work material in which the stud is driven for driving the stud to the correct depth.

Accordingly, the possibility, which exists in a conventional stud driver, of mating an improper propellant charge with a stud to be driven is greatly minimized if not virtually eliminated in the present stud driver. As noted earlier, however, and as is well-known to those skilled in the art, there always exists the possibility of firing a stud into a workpiece or workpiece area which is softer than anticipated and which would permit travel of the fired stud completely through the work unless the stud were restrained or captivated by the tool. The safety collar 60 of the present stud driver and the safety head 32 on the stud 12 of each present ammunition round 10 cooperate to provide this stud-captivating action.

In connection with this stud-captivating action, attention is directed to FIG. 4 wherein it will be observed that the safety collar 60 has a front wall 150 which is spaced from the front end of the barrel 42 to define therebetween an internal annular groove or recess 154. This recess has an outside diameter slightly greater than the diameter of a circle centered on the axis of each stud 12 and circumscribing the safety head ribs 38 of the stud. Opening through the front safety collar wall 150, on the axis of the barrel bore 44, is a circular opening 156 of about the same diameter as the bore. Wall 150 also has three uniformly spaced notches 158 of about the same cross-section as the barrel grooves 148. These notches open radially into the front collar wall opening 156 and are angularly displaced from the barrel grooves 148. It is now evident, therefore, that in the event of excessive penetration of a fired stud 14 into a workpiece W, the stud will be finally arrested by engagement of its safety head ribs 38 with the front wall 150 of the safety collar 60. The stud is thus captivated by the stud driver until deliberately released. Such release is accomplished by rotating the tool relative to the driven stud to a position wherein the safety collar notches 158 are aligned with the safety head ribs on the driven stud and then retracting the tool rearwardly from the stud.

The operation of the illustrated stud driver 40 is now believed to be obvious. Briefly reviewing this operation, the stud driver is conditioned for firing by removing the ammunition magazines 56a, 56b from the breech frame 52 and loading each magazine with the proper number of ammunition rounds 10. The magazines are then reinstalled on the tool, whereupon the tool is readied for use.

During such use, the stud driver is pressed forwardly against a workpiece W with the axis of the barrel 42 normal to the work surface. This action initially actuates the interlock means 104 to release the safety shield 102 for retraction relative to the barrel. Continued forward pressure of the tool against the workpiece now results in forward extension of the barrel relative to the shield, and hence relative retraction of the shield relative to the barrel, until the front end of the safety collar 60 bottoms against the work surface. This relative retraction of the safety shield 102 along the barrel 42 drives the breech cylinder 50 to transport an ammunition round 10 from one of the ammunition magazines 56a or 56b to firing position. At this point, the trigger 98 of the tool is depressed to fire the round currently in firing position and thereby effect the forward propulsion of its contained stud 12 into the workpiece.

Returning now to the operation of the illustrated stud driver, excessive penetration of a fired stud 12 into the workpiece W is prevented or limited by engagement of the stud safety ribs 38 with the front wall 150 of the safety collar 60. The tool is removed from such a fired stud by rotating the tool to a position wherein the front safety wall notches 158 are aligned with the stud ribs and then withdrawing the tool rearwardly from the stud. After each stud is driven into the workpiece, the safety head of the stud may be easily removed by merely snapping or breaking the slender connecting stem 34 between the head and the stud proper.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Fastener ammunition for a fastener driving tool including a barrel with internal longitudinal grooves spaced circumferentially about and extending parallel to the axis of the bore through said barrel, and a firing chamber for receiving said ammunition and having a firing position wherein said chamber opens forwardly to said bore, comprising:

a cartridge case having internal longitudinal grooves spaced circumferentially about and extending parallel to the longitudinal axis of said case;

a fastener positioned longitudinally within said cartridge case having a front shank portion, a rear head with radially projecting ribs in planes containing the longitudinal axis of the fastener and engaging in said grooves, and a relatively slender stem joining said head and shank to permit removal of said head by breaking said stem; and

a propellant charge in said cartridge case for propelling said fastener forward from said cartridge case.