Powder-Actuated Tool With Power Adjustment and Angle-Fire Control

The present invention relates to powder-actuated tools and, more particularly, to means for adjusting the power level of indirect-acting power actuated fastener driving tools.

Powder-actuated fastener driving tools, of the indirect-acting type, comprise, in general, a piston, the rear end of which slides into an expansion chamber for the gases produced by the combustion of the propelling charge.

It is known in the art to continuously adjust the power level of such tools by modifying the initial volume of the expansion chamber through relative axial displacement of two chamber-defining tool parts. Such a displacement may for example, be realized by screwing one part, including the cartridge chamber, onto another part which includes stop means defining the piston battery position.

It is also known in the art to provide a safety interlock, for such tools, preventing tool discharge unless the tool muzzle is firmly pressed against the work piece. Such an interlock may, for example, be realized by a barrel slideably carried in the tool receiver and biased toward a forward or loading position, and a firing mechanism operable only when the barrel is in a rearward or battery position. Further, the receiver, which is telescoped over the barrel, may be adapted to limit access thereto, such that rearward displacement of the barrel may be accomplished only when the tool is substantially perpendicular to the work surface. This feature is commonly known as angle-fire control and is intended to prevent discharge of the tool under conditions wherein ricochet of the fastener may occur.

Unfortunately, the above-described power adjustment technique alters the axial relation of the barrel and the receiver. It is, therefore, presently impossible to incorporate in such a tool, both the power adjustment and constant angle-fire control features.

It is a primary object of the present invention to provide an improved indirect-acting powder actuated tool, incorporating an angle-fire control, wherein the power level is continuously variable. This is accomplished, in general, by a tool wherein a barrel and a barrel breech are adjustably screwed together and telescopically carried by a slide assembly which, in turn, is telescopically carried by the tool receiver. More specifically, the slide assembly and the barrel are operably connected for corotation, whereby rotation of the slide assembly produces a joint axial displacement of the barrel and the slide assembly, relative to the barrel breech, nevertheless, are axially displaceable, relative to the sleeve assembly, between a loading position and a battery position. Thus, the axial relation between the slide assembly and the barrel is preserved during power level adjustment and this constant relationship is utilized to effect angle-fire control by means of a firing mechanism which is operable solely when the barrel and the barrel breech are in the battery position. Further, the ability of the tool to accept fasteners of differing lengths is unaffected by power adjustment. Means are provided biasing the barrel and the barrel breech toward the loading position, it being possible to overcome the biasing means by pressing the barrel muzzle against the work surface, while the tool is substantially perpendicular thereto.

The above and other objects, as may hereinafter appear, may be more clearly understood by reference to the following detailed description of the preferred embodiment, the appended claims and the drawing wherein:

FIG. 1 is a side cross-sectional view of an indirect-acting powder-actuated fastener driving tool, arranged and constructed in accord with the present invention, wherein the barrel and barrel breech are in the loading position and adjusted for maximum power output;

FIG. 2 is a fragmentary top cross-sectional view of the tool of FIG. 1;

FIG. 3 is a side cross-sectional view, similar to FIG. 1, showing the tool in condition ready to be fired; and

FIG. 4 is a side cross-sectional view similar to FIG. 1, wherein the tool is adjusted for minimum power output.

In the drawing, there is shown an indirect-acting powder-actuated fastening tool including a barrel 1 having a longitudinal bore 1a, a breech end 1b and a muzzle end 1c. A piston 3, having a head 3a, is slidably disposed within the barrel bore 1a. A barrel breech 5 is threadedly carried on the breech end 1b of the barrel 1 and includes a cartridge-receiving chamber 5a communicating with a gas expansion chamber 5b adapted to receive a portion 3b of the piston head 3a in gas-tight sliding relation. An inwardly projecting lip 1d is provided, proximate the breech end 1b of the barrel 1, cooperating with a second portion 3c of the piston head 3a to limit its motion toward the cartridge-receiving chamber 5a.

A slide assembly 7 is telescoped over the barrel 1 and the barrel breech 5, both of which are jointly axially displaceable, relative to the slide assembly 7, between a forward or cartridge loading position, as seen in FIG. 1 and a rearward or battery position, as seen in FIG. 3.

A barrel sleeve 9 is disposed intermediate the muzzle end 1c of the barrel 1 and the slide assembly 7, both of which are operatively connected, for reasons which will be more fully explained hereinafter, by means of a key 11, slidably carried in a longitudinal slot 9a in the barrel sleeve 9. Key 11 includes portions 11a and 11b extending into longitudinal slots 1e and 7a in the barrel 1 and the slide assembly 7, respectively. A spring retaining ring 12 secures the key 11 against accidental dislodgement. The barrel sleeve 9 is operably connectable to the barrel 1, during rearward repositioning of the piston 3, by means of a ball 13, carried in a bore 9b in the barrel sleeve 9, extendable into a recess 1f in the barrel 1.

A receiver sleeve 15 is disposed intermediate the breech end 1b of the barrel 1 and the slide assembly 7 and is threadedly carried on the barrel sleeve 9.

A slide assembly 7 is telescoped into the tool receiver 17, to which the receiver sleeve 15 is threadedly connected. A retaining screw 19 secures the receiver sleeve 15 against being unscrewed from the receiver 17 during operation of the tool and, more importantly, it engages a slot 5c in the barrel breech 5, whereby the same is prevented from rotating relative to the receiver 17.

The receiver 17 also supports a firing mechanism including a cocking slide 21, disposed rearwardly of the barrel breech 5, axially displaceable between a forward position, and a rearward, or cocked position, pursuant to displacement of the barrel 1 and the barrel breech 5 from the cartridge loading position to a battery position. A helical barrel spring 23 biases the cocking slide 21 toward the forward position and further serves to bias the barrel 1 and the barrel breech 5 toward the cartridge loading position.

A rebounding firing pin 25, mounted on a firing pin slide 27, is biased toward contact with a cartridge C by a helical firing pin spring 29. A spring-loaded firing pin pawl 31, carried by the firing pin slide 27, engages the cocking slide 21.

A trigger bar 33, operatively connected to a trigger 34 is disposed to rotatably displace a spring-loaded sear 35 to disengage the firing pin pawl 31 from the cocking slide 21 when the latter is in the cocked position.

Forwardly of the barrel 1, and concentric therewith, the barrel sleeve 9 supports a buffer housing 37 carrying an elastomeric buffer 39 adapted for cooperation with the portion 3c of the piston head 3a consequent to discharge of the tool.

A tiltable muzzle bushing B, of the type described in copending patent application Ser. No. 158,952, is preferrably carried by the slide assembly 7, forwardly of the buffer housing 37, and includes a member b which constitutes, in effect an axially displaceable extension of the barrel 1 and a muzzle bushing cam c which is fastened to the barrel sleeve 9.

As shown in FIG. 1, the tool is adjusted for maximum power output, with the barrel 1 screwed against the barrel breech 5. The initial volume of the gas expansion chamber 5b is, thus, at a minimum, while the length of the power-stroke, i.e. the distance that the piston must travel before the expansion gases may escape around the piston head, is a maximum. It is to be noted that the bore diameter of the passage past the barrel lip 1d is significantly greater than the diameter of the gas expansion chamber 5b, whereby the power stroke terminates at the chamber mouth. The barrel 1 and the barrel breech 5 are shown in the cartridge-loading position, while the cocking slide 21 and the firing pin slide 27 are in the forward position.

In FIG. 3, the tool has been cocked, preparatory to discharge, by pressing the muzzle end bushing member b against the work surface S. The barrel 1 and the barrel breech 5 have thus been axially displaced, against the influence of the cocking slide spring 23, to the battery position, whereat the cartridge receiving chamber 5a has telescoped over a cartridge C, while the cocking slide 21 and the firing pin slide 27 have been displaced to the cocked position. In this regard, it will be readily appreciated that the diameter of the slide assembly 7 is such as to preclude full displacement of the aforementioned parts unless the tool is substantially perpendicular to the work surface S.

In FIG. 4, the tool is shown adjusted for minimum power output, with the barrel 1 unscrewed from the barrel breech 5, whereby the initial volume of the gas expansion chamber 5b is at a maximum and the length of the power stroke is at a minimum.

Power adjustment is effected by rotation of the slide assembly 7, which, acting through the key 11, causes the corotation of the barrel sleeve 9 and the barrel 1, relative to the barrel breech 5 and the receiver sleeve 15. This relation rotation results in the desired axial separation of the barrel 1 and the barrel breech 5, while, at the same time, effecting a corresponding axial separation of the barrel sleeve 9 and the receiver sleeve 15. It is, at this point, to be understood that the screw connections between the barrel 1 and the barrel breech 5 and between the barrel sleeve 9 and the receiver sleeve 15 have the same thread pitch.

As the barrel 1 and the barrel sleeve 9 are displaced away from the barrel breech 5 and the receiver sleeve 15, they correspondingly displace the muzzle bushing B and the slide assembly 7. Thus, the axial relation between the slide assembly 7 and the barrel 1 and bushing member b is undisturbed by power level adjustment of the tool, whereby the angle-fire control is maintained.

It is, thus, to be noted that power adjustment does not change the length of piston travel during firing and does not affect the capacity of the tool to accept fasteners of different lengths.

To disassemble the tool, as for cleaning, the retaining screw 19 is removed, freeing the barrel breech 5 for corotation with the barrel 1. The entire barrel/slide assembly, less the receiver sleeve 15 which remains attached to the receiver 17, is now unscrewed from the receiver 17 by rotation of the slide assembly 7. The slide assembly 7 is moved to its extreme forward position, allowing removal of the retaining ring 12 from the barrel sleeve 9. The key 11 is now removed and the barrel 1 and barrel breech 5 are withdrawn from the barrel sleeve 9, as may the buffer housing 37 and the buffer 39. The piston 3 is now slide from the barrel 1 and the barrel 1 and barrel breech 5 are unscrewed. Lastly, the muzzle bushing cam c is removed from the barrel sleeve 9, allowing removal of the barrel sleeve 9 from the slide assembly 7.

Reassembly is essentially accomplished in reverse order of disassembly, it being necessary, however, to insure that the retaining ring 12 does not overlie the ball 13 and that the tool parts are properly set prior to lockup. This may be readily accomplished by screwing the barrel 1 completely into the barrel breech 5. The barrel/slide assembly is inserted into the receiver sleeve 15 and screwed to its furthest breechward position and then backed off suficiently to permit insertion of the retaining screw 19 in the slot 5c in the barrel breech 5.

While reference has been made above to a particular embodiment of the invention, various alterations and modifications will readily suggest themselves to those skilled in the art. Accordingly, the scope of this invention is intended to be limited solely by the following claims.