Pneumatic Stapler Device

Abstract

A pneumatically operated stapler device is provided with a control valve appliance which enables single or repeated working strokes with adjustable sequence and which is operated by compressed air admitted by an air duct communicating the chamber of said control valve with an additional air chamber of the working cylinder.

Description

DISCLOSURE OF THE INVENTION

This invention relates to a pneumatically operated stapler device, particularly for driving staples, nails and other fastener means into a workpiece, with a control valve appliance to perform single or continuous working strokes. This control valve is hand-operated to connect the working cylinder of the stapler with the compressed air supply duct or with the open air, and is provided with an auxiliary appliance for automatically repeating the working cycles which are initiated by actuation of the control valve.

It is an object of this invention to provide a control valve appliance of the above-mentioned type to perform single and repeated working strokes.

Another object of the invention is to provide a simple and easily adjustable auxiliary apparatus to control the sequence of percussions performed by the working cycle of the stapler device.

According to this invention, an additional chamber of the working cylinder receiving compressed air for returning the piston to its initial position communicates, via an air port, with a valve chamber containing the control valve in which valve chamber an auxiliary valve submitted to the pressure of an adjustable resilient force is provided for the purpose of adjusting the sequence of the working cycles. This auxiliary valve permits an easy adjustment of the mode of operation of the device by a mere modification of the tension of its spring so that the device may be used in a simple manner either in intermittent or in continuous operation or, alternatively, in one of the two modes of operation. The space required by this auxiliary valve is small and may easily be provided in the body of the device in the proximity of the manually actuated control valve.

Further objects and features of this invention are described with reference to the accompanying drawings.

In the drawings:

FIG. 1 shows in side elevation partly shown in section a stapling device driven by compressed air with an embodiment of the invention;

FIG. 2 shows, at a larger scale, the longitudinal section of the control valve appliance according to the invention in the position when the device is out of operation.

Referring to FIG. 1, the stapler device consists of a hollow housing body 1 developed to form a handle which housing body 1 is provided, at its rear end, with a conduit 2 for a connection with a supply of compressed air (not shown). A compressed air reservoir 3 is arranged in the housing body 1 and permanently connected to the compressed air supply. The compressed air reservoir forms a storage chamber which, via a control valve 4, communicates with a passage 5 leading to the working cylinder 6 arranged in the front part of the housing body 1. In the latter, a piston 7 having a resilient bumper 60 is guided in known manner which piston 7 actuates a driver 8 which separates the staples from the magazine 9 arranged in the bottom of the housing body 1 and drives them into the workpiece. During the working stroke of the piston 7, the cylinder 6 is vented to the atmosphere through an exhaust outlet 61 in the cylinder bottom and a lateral slot 62 in the nose of the device. The outlet 61 is sealed off by the bumper 60 when the piston 7 reaches the end of its working stroke. Beneath the compressed air reservoir 3, a vent duct 10 is provided which, via the control valve 4, communicates with the passage 5 when, after the completion of its working stroke, the piston 7 is returned to its initial position as represented in FIG. 1.

As shown in detail in FIG. 2 the control valve 4 comprises a substantially cylindrical valve housing 11 which, by means of a thread 12, is screwed into a bore 13 of the housing body 1. The control valve 4 is provided with a stepped valve body 14 slidably mounted on a release valve stem 16 provided with an axial bore 15. The lower end of the release valve stem 16 is developed to form a pin 17 which is provided with an operating element, for instance a finger tip plate 18.

The upper end of the valve housing 11 projects into the compressed air reservoir 3 and is provided with a port 19, through which the compressed air in the reservoir 3 acts on the upper face of the valve body 14. At the mouth of the passage 5, the valve housing 11 is provided, in two diametrically opposed points, with a cutout 20 over which a shoulder 21 is arranged which serves as a seat for an inlet valve. In normal position as shown in FIG. 2, a sealing ring 22 arranged in a recess of the valve body 14 presses tightly against the shoulder 21 and thereby interrupts the communication between the passage 5 and the compressed air reservoir 3. A valve seat 23 arranged below the cutout 20 is sealed by a sealing ring 24 which, in normal position, is raised from the valve seat 23 and thereby communicates, via a further cutout 25 of the valve housing 11, the passage 5 with the vent duct 10.

The lower end of the valve body 14 is provided with a larger operative face than the upper end permanently exposed to the action of the compressed air. Against the enclosing cylindrical part of the valve housing 11, this lower end is sealed by a sealing ring 26. Below the valve body 14, a slide valve 27 of the same diameter as the lower end of the valve body 14 is slidably mounted on the release valve stem 16 and, against the latter, is sealed by a sealing ring 28, whereas, against the inner wall of the valve housing 11, it is sealed by a sealing ring 29. The slide valve 27 controls several ports 30 provided at the same radial level and communicating with an air passage 31. Furthermore, the slide valve 27 is sealed, by an elastic disc 33, against the annular face at the lower end of the valve body 14 which is provided with radial slits 32. By cross bores 35 provided in the release valve stem 16, the valve housing space 34 below the slide valve 27 is in open communication with the axial bore 15 of the latter and, at its lower end, has an elastic bottom plate 37 which, like the bottom 38 of the valve housing 11, is provided with a central cutout 39 of a larger diameter than the pin 17 of the release valve stem 16.

In the initial position of the parts as shown in FIG. 2, an annular shoulder 36 of the release valve stem 16 seals the cutout 39. Beyond this, in this position, the release valve stem 16 is slightly spaced from an elastic liner 41 arranged on the upper end wall 40 of the valve housing 11 so that the compressed air in the air reservoir 3 can flow via the axial bore 15 to the lower valve housing space 34 where it can act on the lower end of the slide valve 27. As the latter is provided with a larger operative area than the upper end of the valve body 14 permanently exposed to the action of the compressed air, the latter is pressed upwards into the position shown in FIG. 2 by the compressed air acting on the slide valve 27. In this position, the cutout 20 is closed against the compressed air reservoir 3 by the sealing ring 22 pressed against the inlet valve seat 21, and the passage 5 is in communication with the vent duct 10 via the opened valve seat 23.

The air passage 31 leading from the ports 30 in the lower part of the valve housing 11 communicates with an auxiliary valve 42, the cylindrical housing 43 of which is arranged in a bore 44 of the housing body 1 adjacent an additional chamber 45 of the working cylinder 6. Through two rows of ports 46 and 47 (of FIG. 1) this additional chamber 45 receives the compressed air required to return the piston 7, after completion of its working stroke, into its initial position shown in FIG. 1. The chamber 45 communicates with the auxiliary valve 42 by a port 48 provided in the upper part of the auxiliary valve housing 43 in which a valve piston 49 is slidably mounted under the action of a compression spring 51. The upper face of this valve piston 49 is conical in shape and by the two O-shaped rings 50 the piston is sealed against the inner wall of the auxiliary valve housing 43. At its upper end, the compression spring 51 is enclosed by a tubular extension 52 of the valve piston 49 and, at its lower end the spring 51 is enclosed by a sleeve 53. The lower or opposite end of the spring 51 is supported by a hollow bolt 54 the axial bore 55 of which is in open communication with the open air. A screw cap 56 is attached to the bolt 54 and is screwed on an external thread 57 of the auxiliary valve housing 43.

The operation of the control valve appliance is as follows:

For the execution of a working stroke of piston 7, the finger tip plate 18 of control valve 4 is pressed upwards whereby the upper end of the release valve stem 16 comes to rest against the elastic liner 41 and thus is closed against the compressed air reservoir 3. At the same time, the lower valve housing space 34 is vented, via the cutout 39, by the rise of the annular shoulder 36. By the pressure of the compressed air from the compressed air reservoir 3 acting on its upper face, the valve body 14 is moved downwards whereby the inlet valve 21 is opened and the valve 23 leading to the vent duct 10 is closed. Now, the compressed air flows, through the passage 5, to the upper face of piston 7 which makes its working stroke and, via the ejector slot, drives a staple from the magazine 9 into the workpiece.

At the end of the working stroke, the cylinder exhaust outlet 61 is closed by the bumper 60 and the compressed air acting on piston 7 flows, through the upper narrow ports 46, into the additional chamber 45 from which it reaches, through the larger ports 47, the lower annular area between the bumper 60 and the bottom of piston 7 and returns the latter into its initial position, as the bottom outlet 61 of the working cylinder 6 is closed by the lower part of piston 7 and the cylinder space over piston 7 is vented.

Part of the compressed air which, at the end of the working stroke of piston 7, has penetrated into the additional chamber 45, flows, through port 48, into the auxiliary valve housing 43 and acts on the conical edge of the upper face of the auxiliary valve piston 49 submitted to the action of the compression spring 51. When the initial tension of the compression spring 51 adjusted by means of the screw cap 56, is overcome by the pressure of the compressed air from the additional chamber 45 acting on the auxiliary valve piston 49, the latter is moved downwards and gives access to the air passage 31. This causes the compressed air to penetrate between the slide valve 27 and the lower end of valve body 14 and to press the latter upwards so that the valve seat 21 is sealed. This causes the sealing ring 24 to be raised from its valve seat 23 so that the compressed air over piston 7 may escape, through the passage 5 and the opened cutout 25, into the atmosphere and the piston 7 regains its initial position. As the pressure in the chamber 45 decreases upon return of the piston 7 to its initial position, the spring 51 causes the valve piston 49 to return to its FIG. 2 position and the air passage 31 is vented to the atmosphere through the interior of the auxiliary valve housing 43 and the bore 55.

As, during the working stroke of piston 7, the lower valve housing space 34 is vented and as, on the other hand, the compressed air from the reservoir 3 acting on the upper face of the valve body 14 is under a higher pressure than the compressed air in the passage 31, the valve body 14 is moved downwards and opens the inlet valve 21 so that fresh compressed air flows, through the passage 5, into the working cylinder 6 and immediately acts on the piston 7 which had returned to its upper end position so that the latter again makes its working stroke. This cycle is repeated until the operator releases the finger tip plate 18, thus causing the cycle to terminate.

By modifying the initial tension of compression spring 51 by means of the screw cap 56, the sequence of the working cycles of piston 7 may be adjusted to a large extent, the sequence of percussions, within a certain unit of time, being increased along with the decrease of the initial tension of the compression spring 51. If, on the other hand, the screw cap 56 is screwed further on to the thread 57 whereby the initial tension of the compression spring 51 is increased, the compressed air from the additional chamber 45 acting on the upper conical face of the auxiliary valve piston 49 can no longer move the auxiliary valve piston 49 downward against the action of the strong initial tension of the compression spring 51 so that then the auxiliary valve 42 practically becomes ineffective and the device only makes individual percussions initiated, in each case, by the finger tip plate 18. By the mere action of the screw cap 56, the percussion speed of the device may thus be controlled to a large extent for which purpose the screw cap 56 may be provided, on the outside, with a knurled surface as shown in FIG. 1.

Claims

I claim:

1. In a pneumatically operated stapler device having a body with a compressed air reservoir, a working cylinder, and a working piston and staple drive reciprocably disposed in said cylinder and adapted to be driven in a working stroke from an initial position to a terminal position in said cylinder; the improvement which comprises the combination of:

an air chamber adjacent said cylinder, said cylinder having a wall with first port means for admitting compressed air from said cylinder to said chamber after completion of said working stroke and second port means for admitting compressed air from said chamber to said cylinder for returning said working piston from said terminal position to said initial position;

control valve means regulating the passage of compressed air from said reservoir to said cylinder and the venting of air from said cylinder, said control valve means being manually operable for initiating operation of the device;

air passage means communicating between said chamber and said control valve means;

auxiliary valve means interposed in said air passage means and comprising a valve housing, a valve piston movably disposed in said valve housing, spring means acting on one side of said valve piston, and adjustable means for regulating the spring force, and

said valve housing having port means for subjecting the opposite side of said valve piston to the air pressure in said chamber so as to admit compressed air from said chamber to said control valve means for actuating the latter when the air pressure in said chamber overcomes the force of said spring, whereby to obtain automatic repetitive operation of the device, and said valve piston being nonresponsive to the air pressure in said chamber in one position of said adjustable means for obtaining nonautomatic operation of the device.

2. The device of claim 1 further characterized in that said control valve means comprises a movable valve body arranged to regulate the passage of air from said reservoir to said cylinder and the venting of said cylinder, and a shiftable slide valve member adapted to control the flow of air through said air passage means.

3. The device of claim 2 further characterized by the provision of a manually actuable tubular valve stem having said valve body and said slide valve member slidably mounted thereon, said valve stem in its unactuated position providing fluid pressure communication between said reservoir and said slide valve member for normally holding said valve body and said slide valve member in their inoperative positions, and said valve stem in its manually actuated position permitting movement of said valve body and said slide valve member to their operative positions in response to air pressure in said reservoir, said valve body being thereafter movable to its inoperative position away from said slide valve member in response to air pressure in said air passage means.

4. The device of claim 1 further characterized in that said adjustable means comprises a screw cap having an adjustable threaded connection with said valve housing.

5. The device of claim 4 further characterized in that said screw cap is attached to a tubular element having an axial bore communicating the interior of said valve housing with the open air, and said tubular element engages said spring for adjusting the compression of the spring by manipulation of said screw cap.