Fastener Driving Tool With Pneumatically Clamped Nosepiece Structure

Abstract

A pneumatic fastener driving tool using a compressed air driven fastener driver includes a housing supplied with compressed air. A nosepiece on the housing forms a drive track for the driver to which fasteners are supplied below the driver. An opening through the nosepiece into the drive track is closed by a movable closure held in place by a pneumatic clamping assembly. This assembly includes a piston and cylinder supplied with compressed air from the housing for biasing a lever engaging the closure. A manually actuated release valve in the piston releases the bias to permit movement of the closure to clear jams. A fulcrum for the lever is also removable to permit opening of the closure to clear difficult jams.

Description

This invention relates to a pneumatic fastener driving tool and, more specifically, to such a tool including new and improved means for clearing jams of fasteners from a drive track.

A problem frequently encountered in pneumatic fastener driving tools is the jamming of fasteners in the drive track during the drive stroke. This involves not only the wedging of the fastener, such as a staple, in the drive track or the partial ejection of the fastener from the drive track, but also the "freezing" of the driver in the drive track so that it is not returned to its normal position at the end of the driving stroke. This disables the tool until the jam can be cleared. It is a long accepted practice to provide removable or movable closures in the drive track defining structure to permit access to the track to clear the jam. Some of the closures are held or retained in position by removable threaded fasteners such as machine screws, and others are held in position by a resilient bias, either directly or through an intermediate assembly such as a cam mechanism.

These expedients are not useful in the tools now being manufactured which drive larger and larger fasteners such as 16 penny nails and which require greater and greater driving forces. If the closure is retained by threaded fasteners, the wedging of the driver or fastener against the closure stresses the threaded fasteners to the extent that they can be removed only with difficulty. If the closure is resiliently biased to its closed position, the biasing forces required are so great that the clamp for the closure is hard to release.

Accordingly, one object of the present invention is to provide an easily opened closure for clearing jams which is useful in tools for driving large fasteners or tools in which large driving forces are applied.

Another object is to provide a pneumatic clamping assembly for a drive track closure that both provides large clamping forces and is easily opened.

In accordance with these and many other objects, an embodiment of the present invention comprises a pneumatic fastener driving tool of a conventional construction including a pneumatically actuated fastener driving blade, the lower end of which is slidably received within a drive track formed in a nosepiece structure. The nosepiece structure has connected thereto a magazine for supplying successive fasteners beneath the lower end of the blade to be driven thereby. The nosepiece structure includes an access opening closed by a closure held in position by a pneumatic clamping assembly. This assembly includes a cylinder formed in the nosepiece structure containing a piston coupled to one end of a lever, the other end of which bears against the closure. A fulcrum carried on the nosepiece structure engages the lever intermediate its end so that when fluid derived from the housing of the tool is supplied to the cylinder, the piston and lever pneumatically bias or clamp the closure in a position closing the access opening to the drive track. By the selective positioning of the fulcrum, a substantial mechanical advantage is obtained which permits a relatively small piston and cylinder to apply a relatively large clamping force to the closure. valve on the piston can be manually force to the A valve on the piston can be manually actuated when a jam is encountered to remove the clamping bias and permit limited displacement of the closure. This usually will permit the return of the driver blade to its normal position, and reoperation of the tool is sufficient to eject the partially driven fastener and thus clear the jam.

If this does not clear the jam, the fulcrum is movably mounted on the nosepiece and can be removed to permit a substantial displacement of the closure so the jam can be manually cleared. The release of the release valve returns the pneumatic bias, and the tool is returned to its operative condition with the closure biased to a position closing the opening into the drive track.

Many other objects and advantages of the present invention will become apparent from considering the following detailed description in conjunction with the drawings in which:

FIG. 1 is a front elevational view of the nosepiece of a fastener driving tool illustrating the removable closure and the pneumatically biased clamping means embodying the present invention;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a bottom elevational view of the nosepiece structure shown in FIG. 1; and

FIG. 4 is an exploded perspective view of the closure and clamping means embodying the present invention.

Referring now more specifically to the drawings, therein is illustrated a portion of a pneumatic fastener driving tool which is indicated generally as 10 and which includes a nosepiece structure 12 secured thereto in which is formed a drive track 14. The drive track 14 slidably receives the lower end of a fastener driving blade 16 and receives elongated fasteners 19 to be driven from a magazine assembly indicated generally as 18. A portion of the drive track 14 is provided by a removable or movable closure or wall member 20 which is releasably held in position defining a portion of the drive track 14 by a pneumatic clamping assembly indicated generally as 22. The clamping assembly 22 utilizes pressurized fluid from the tool 10 and a mechanical advantage to retain the closure 20 in position when subjected to the increased displacing forces occasioned by driving large fasteners and is easily released by venting the pressurized fluid to permit the closure 20 to be displaced to facilitate the clearing of a jammed fastener 19 or blade 16.

In general, the pneumatic fastener driving tool 10 with which the present invention can be used can be of any of the types well known in the art such as the tool shown in U.S. Pat. No. 3,176,592 or in U.S. Pat. No. 3,498,517, issued Mar. 3, 1970, and which is assigned to the same assignee as the present application. In general, this tool includes a housing 24 for the tool containing a cylinder 26 in which is slidably mounted a fluid actuated piston (not shown) for operating the driver blade 16. The interior of the housing 24 provides a reservoir or cavity 28 continuously supplied with a pressurized fluid such as compressed air. The housing 24 for the tool 10 is completed or closed by the nosepieces structure 12 which is bolted to the remainder of the housing 24 by a plurality of threaded fasteners 30. The magazine assembly 18 is secured to the nosepiece structure 12 and includes suitable well known follower or pusher means for feeding the fasteners or staples 19 into the drive track 14 in succession through an inlet opening 32 (FIG. 2) in a wall of the nosepiece structure 12 opposite the closure 20.

The nosepiece structure 12 is formed of one or a pair of rigidly joined members defining a generally centrally located and longitudinally extending slot forming the drive track 14. The outer wall of the structure or the wall opposite the magazine assembly 18 is formed with an opening 34 (FIG. 4) aligned or coextensive with the lower portion of the slot forming the drive track 14. The adjacent surfaces of the nosepiece structure 12 are provided with shoulders 12A (FIGS. 3 and 4).

The closure 20 generally corresponds in shape to the configuration of the opening 34 in the nosepiece structure 12 and includes a pair of shoulders 20A which, when the closure or wall member 20 is disposed within the opening 34, engage or rest on the shoulders 12A of the nosepiece structure 12. As illustrated in FIGS. 2 and 3, an inner wall 20B on the closure 20 defines one wall of the drive track 14. To aid in locating the closure 20 on the nosepiece structure 12, an upper end thereof is formed with a recess 36 in which is disposed a pin 38, the opposite ends of which are received in aligned recesses 39 in the front wall of the nosepiece structure 12.

As set forth above, the clamping assembly 22 is pneumatically operated to clamp or bias the closure 20 in its proper position on the nosepiece structure 12. The clamping assembly 22 includes a cylinder 40 formed in the front wall of the nosepiece structure 12 which slidably receives therein a piston 42 carrying a resilient o-ring 44. The piston 42 includes an outer cylindrical portion 42A slidably received with some clearance within an opening 46 formed in one end of a lever 48. The other end of the lever 48 includes an arcuate or rounded portion 48A which bears against the outer wall surface of the closure 20. The lever 48 includes another rounded or arcuate portion 48B intermediate the ends of the lever 48 but closely adjacent the rounded portion 48A. The rounded portion 48B provides a fulcrum about which the lever 48 is pivoted.

This fulcrum is provided by a bar 50 which is mounted on the front wall of the nosepiece structure 12 by a pair of machine screws 52 and 54 which pass through the bar 50 and a pair of spacing sleeves 56 to be threadedly received within aligned openings in the front wall of the nosepiece structure 12. The machine screw 52 passes through an opening 58 in the bar 50, while the machine screw 54 is received within an upwardly open notch 60 therein. The machines screws 52 and 54 are normally tightened to the point at which the bar 50 is held in a predetermined position spaced outwardly from the outer wall of the closure 20 but carried on the nosepiece structure 12 with the lever 48 disposed between the spacing sleeves 56 and interposed between the bar 50 and the closure 20.

To provide means for operating or biasing the lever 48, compressed air from the cavity or reservoir 28 in the housing 24 of the tool 10 is forwarded to the inner end of the cylinder 40 through a passageway 62 (FIG. 2) in the housing 24 and a connected passageway 64 in the nosepiece structure 12. The pressurized fluid supplied from the reservoir 28 acts on the inner circular surface of the piston 42 and biases this piston to the left (FIG. 2) so that the outer surface of this piston bears against the lever 48 and pivots this lever in a counterclockwise direction about the fulcrum defined by the point of contact between the bar 50 and the rounded portion 48B. This forces the rounded portion 48A of the lever 48 against the adjacent wall surface of the closure 20 to clamp this closure in its predetermined position on the nosepiece structure 12 closing the drive track 14. Because of the 50 to 100 pound pressure of the fluid normally supplied to the reservoir 28, a relatively small area piston 42 coupled with the mechanical advantage obtained by the location of the fulcrum point for the lever 48 permits the clamping assembly 22 to apply a rather large retaining force to the closure 20 to insure that this closure remains in its predetermined position, even when subjected to rather large displacing forces arising from driving a fastener 19 through the drive track 14.

In the event that a fastener 19 or the lower end of driver blade 16 becomes jammed or wedged in the drive track 14 during operation of the tool 10, the clamping assembly 22 is easily released to facilitate or permit the clearance of the jammed condition. The clamping assembly 22 is released by actuating a valve assembly indicated generally as 62 (FIG. 2) to exhaust the pressurized fluid from the cylinder 40. The valve assembly 62 includes a valve stem 64, the inner end of which is provided with an enlarged and conically tapered portion 64A. The stem 64 extends through a slightly oversized and axially extending bore or passage 66 through the piston 42. When compressed air is supplied to the cylinder 40, the rear surface of the head 64A of the valve stem 64 is forced into engagement with a resilient O-ring 68 disposed within a cylindrical recess in the piston 42 normally occupied by the head portion 64A of the valve stem 64. This seals off communication between the interior of the cylinder 40 and the passageway 66. However, when the clamping assembly 22 is to be released, an enlarged end 64B on the valve stem 64 is depressed and moved to the right (FIG. 2) against the pneumatic bias so that the head portion 64A moves out of engagement with the O-ring 68. This vents or exhausts the pressurized fluid within the cylinder 40 to the atmosphere and removes the pneumatic clamping or biasing force supplied by the lever 48 to the closure 20.

This release of the biasing force is generally adequate to permit the return of the driver blade 16 to its normal or retracted position shown in FIG. 2. The tool 10 can then be operated with the clamping assembly 22 released. In most instances, the reoperation of the tool in forcing the driver element 16 downwardly is sufficient to clear the jammed fastener 19 from the drive track 14 and restore the tool 10 to an operative condition. The valve assembly 62 can then be released so that pressurized fluid is again accumulated in the cylinder 40 and the lever 48 is actuated to again clamp the closure 20 in its closed position.

If, however, the driver blade 16 or the fastener 19 or both of these elements are so tightly wedged in the drive track 14 that they cannot be released and cleared by reoperation of the tool 10, the operator maintains the release valve assembly 62 in its operated condition so that the lever 48 is not stressed. He then partially releases or retracts the machine screw 54 so that the bar 50 can be pivoted in a clockwise direction about the machine screw 52 to a position clearing the lever 48. The lever 48 can then be lifted from the piston 42, and the closure 20 removed. This permits full access to the drive track 14 and permits the clearance of the jam. These parts can then be restored to their assembled position shown in FIG. 1 and the valve 62 released so that pressurized fluid is again accumulated in the cylinder 40 to restore the clamping force to the closure 20. This can also be accomplished by disconnecting the compressed air from the tool 10.

Accordingly, the fastener driving tool 10 by the use of pressurized fluid for actuating the piston 42 and the mechanical advantage obtained through the use of the lever 48 is capable of applying large retaining forces to the movable closure 20 to prevent its displacement from a position defining a portion of the drive track 14, even when large displacing forces are developed by the use of the power necessary to drive large fasteners. Further, the only force required to remove this clamping or retaining force is that required to actuate the release valve assembly, and the closure 20 can be displaced or removed without having to overcome large resilient biasing forces or attempting to loosen heavily stressed threaded fasteners.

Although the present invention has been described with reference to a specific embodiment thereof, it should be understood that numerous other modifications and embodiments of the invention can be devised by those skilled in the art which will fall within the spirit and scope of the principles of this invention.

Claims

I claim:

1. A fastener driving tool of the type having a housing containing a fluid actuated fastener driver comprising

structure on the housing defining a drive track slidably receiving the fastener driving element, said structure forming an opening into the drive track,

a closure for the opening,

and fluid actuated means coupled to the closure for clamping the closure in a position closing the opening.

2. The fastener driving tool set forth in claim 1 including

valve means for controlling the fluid acting on the fluid actuated means.

3. In a fastener driving tool of the type having a housing supplied with pressurized fluid for operating a piston with a connected fastener driver,

a drive track defining structure carried on the housing for slidably receiving the driver, said structure defining an opening into the drive track,

a wall member movably mounted on the structure closing the opening,

a fluid actuated piston means supplied with fluid from the housing,

and a linkage actuated by the piston means and coupled to the wall member for holding the wall member in a position on said structure closing said opening.

4. A fastener driving tool of the type having a fluid operated driving element, comprising

a housing for said tool adapted to be supplied with pressurized fluid,

structure on said housing defining a drive track for slidably receiving the driving element, said structure having an opening therein to said drive track,

a movably mounted wall member adapted to close said opening,

cylinder means on said housing and supplied with fluid from the housing,

a piston movable in said cylinder and biased by the fluid,

and a linkage actuated by the piston and coupled to the wall member for biasing the wall member into a position closing the opening.

5. The fastener driving tool set forth in claim 4 in which

the linkage includes a lever coupled to the piston and the wall member at spaced points along the lever and having a fulcrum between said points.

6. The fastener driving tool set forth in claim 4 including

valve means for discharging fluid from the cylinder to release the linkage.

7. The fastener driving tool set forth in claim 6 in which

the valve means includes means carried on the piston and movable with the piston.

8. A fastener driving tool of the type having a fluid operated fastener driving element comprising

a housing for said tool adapted to be supplied with pressurized fluid,

structure on said housing defining a drive track for slidably receiving the fastener driving element, said structure also defining an opening into said track,

a closure for said opening movably mounted on the housing,

a cylinder on said housing,

a piston slidably mounted in said cylinder for movement in a direction generally perpendicular to the drive track,

a linkage coupling the piston to the closure,

and means for supplying fluid from the housing to the cylinder to bias the piston to clamp the closure in a position closing the opening.

9. A fastener driving tool of the type having a fluid actuated fastener driver comprising

a housing for the tool adapted to be supplied with pressurized fluid,

a nosepiece structure on the housing defining a drive track for slidably receiving the driver, said structure having an inlet through which fasteners to be driven are supplied to the drive track in one wall and an opening in the opposite wall,

a closure for said opening movably mounted on the structure,

a cylinder in said structure and disposed in said opposite wall above said opening,

a piston slidably mounted in said cylinder,

fulcrum means on said opposite wall spaced from said opening,

a lever engaging the piston and the closure adjacent the opposite ends of the lever and engaging the fulcrum means intermediate the ends of the lever,

and fluid means for selectively applying fluid from the housing to the piston in the cylinder to pivot the lever about the fulcrum and bias the closure against the structure in a position closing the opening.

10. The fastener driving tool set forth in claim 9 in which

the fulcrum means includes a member movably mounted on the structure and extending generally transverse to the lever.

11. The fastener driving tool set forth in claim 9 in which

the fluid means includes passageway means continuously supplying fluid from the housing to the cylinder.

12. The fastener driving tool set forth in claim 11 in which

the fluid means includes a valve for discharging fluid from the cylinder.

13. The fastener driving tool set forth in claim 12 in which

the valve includes a valve seat and a valve stem carried on the piston.

14. The fastener driving tool set forth in claim 9 in which

the lever has an opening adjacent one end,

and the piston has a projecting portion disposed in the opening in the lever to couple the piston and the lever.