US3397828A - Pneumatic air operated fastener driving apparatus - Google Patents

Description

1968 D. VOLKMANN 3,397,828

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 3 Sheets-Sheet 1 o o D 5 I3 14 I 31 Fig.1 32 I NVENTOI? 0/575? VOLAMAlV/V Aug. 20, 1968 D. VOLKMANN 3,397,823

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 3 Sheets-Sheet 2 Fig.2

INKS/V701? 0/5767? VOL/(MANN Aug. 20, 1968 D. VOLKMANN 3,397,828

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 5 Sheets-Sheet 5 76 x z'; A 78 8 33 Fig.3

l/VIENTO}? 0/5727? [WA/(MANN United States Patent 7 Claims. (Cl 227-130) ABSTRACT OF THE DISCLOSURE A pneumatic fastener driving' apparatus has a piston actuated clamping device for clamping a work piece before the fastener is driven into the work piece by a driving piston. To insure a two-cycle system of operation, the cylinders for the two pistons are separated by a partition and compressed air is supplied to the cylinder for the clamping device actuating piston. A tubular guide is provided for the actuating piston and extends through the partition. Compressed air is admitted to the tubular guide through an inlet port and flows into the cylinder for the driving piston only after the actuating piston has substantially completed its working stroke so as to uncover the inlet port 7 The present invention .relates to a pneumatic air operated fastener driving apparatus by which staples and similar fastening means are inserted into a work piece by -a driving piston in cooperation with a clamping device for the work piece which is in the shape of tongs and is connected with a second piston moving in reverse direction of the driving piston and being also operated by compressed air. In a prior construction of a fastener driving apparatus both thesepistons are guided in one joint cylinder into which the compressed air. streams at a point where it can act on the two pistons=in their then inoperativepositions in which their front surfaces are adjacent'to each other. When the control valve of such construction is operated the air acts simultaneously on both pistons. Because of this, there is not suflicient safeguard that the clamping device for the work piece is closed before the driving piston starts its working stroke by which it carries the fastening means from an ejection channel into the work piece. This construction therefore does not provide the necessary working reliability of the apparatus.

It is an important object of the invention to provide'an apparatus in which the working stroke of the driving piston is not allowed to take place before the clamping device which is coupled with the second pistonhas been actuated and has properly arrestedthe work piece.

Another object of the invention is to provide means for a portable apparatus which'do'not release the downward motion of the driving piston for driving the fastener into the workpiece before the second piston has actuated the clamping device for'the workpiece.

A specific object of the invention consists in providing a pneumatic air operated apparatus with a driving piston and an actuating piston for the clamping device in which both pistons are coaxial with each other and permit an easy operation of the apparatus.

In accordance with these and many other objects the invention comprises a pneumatic air operated apparatus for driving staples and other fasteners into a workpiece in which an actuating piston for a clamping device of the workpiece is connected with this device and reversibly of the driving piston guided in a joint cylinder of the body of the apparatus. The air admission channel coming 3,397,828 Patented Aug. 20, 1968 from a control valve is arranged above a partition separating the working spaces of the driving piston and of the actuating piston for the clamping device from each other and being intersected by a channel connecting the two working spaces with each other. This channel is surrounded by the actuating piston for the clamping device and only admits compressed air to the working space of the driving piston after the actuating piston for the clamping device has fully or partly completed its working stroke.

A construction of the apparatus in this manner renders it possible that the actuating piston is made to close the clamping device for the workpiece before the compressed air moves the driving piston by which the fastener is driven into the workpiece. The workpiece is therefore reliably mounted at the time the driving piston thrusts the fastener from the ejection channel into the workpiece. The apparatus safely works according to the two-cycle principle and because of the coaxial arrangement of driving piston and actuating piston it can be easily handled. The handle piece of the body of the apparatus is in accordance with the usual practice situated in immediate neighbourhood of the central axis of the cylinder and its coaxial ejection channel. The apparatus can be used in the same Way as a fastener driving apparatus without the clamping device for the workpiece.

Further advantages and features of the invention including details of construction and combinations of parts will be more particularly described with reference to the accompanying drawings. In the drawings:

FIGURE 1 is a lateral view, partly in section, of an embodiment of the complete apparatus according to the invention;

FIGURE 2 is a partial longitudinal section of the driving part of the apparatu in its initial position;

FIGURE 3 is a partial longitudinal section of the driving part of the apparatus in the terminal position of the actuating piston for the clamping device.

With reference to FIGURE 1, the apparatus has a body 1 which may consist of a light metal cast the rear portion of which has the shape of a handle piece 2 and is provided with an extension 3 for connection to a compressed air supply pipe. Handle piece 2 surrounds a compressed air storage chamber 4 connected to which is via an entrance valve 6, which is operated by a finger lever 5, a compressed air channel 7. The channel 7 ends in a cylindrical casing 8 which is provided in the front portion of the body 1 of the apparatus and is in FIGURES 2 and 3 shown in a larger sectional view. Inserted in casing 8 is a guiding sleeve 9 for the driving piston 10, which via a resilient intermediary piece 11, which may consist of a plastic material or a similar substance, is connected with a driver 12 guided within the ejection channel 14. The latter is in the usual manner connected with a staple magazine 13. Driving piston 10 is also under the stress of a coil spring 15 which returns it into its initial position as shown in FIGURE 2. when it has completed its working stroke.

Below the point where the compressed air channel 7 ends in the cylindrical casing 8 the latter is provided with a partition 16, which is provided with passages 18 sealed by check valve balls 17. Sunk into partition 16 in the central axis of the cylindrical casing 8 is an upwardly extending tube 19 the upper portion of which has a radial bore 20. Tube 19 extends into a cylindrical bore 21 of a bolt 22 which is coaxial with tube 19. The lower end of bolt 22 carries a piston 23 which is tightly guided within a cylindrical sleeve 25 inserted into casing 8 and connected with it by threads 24. The piston 23 is under the pressure of a coil spring 26 which is fastened to its upper surface. The counter bearing for spring 26 is formed by a cap 27 which seals the cylindrical sleeve 25 and'has a vent 28.

As shown in FIGURE 1, a rod 29 is linked to the upper end of the bolt 22 on which the piston 23 is carried and forms an articulated connection with tongs 30 which can be turned around a pivot 31 arranged at the rear lower end of the body 1 of the apparatus and are used to hold a workpiece 32 into which a staple is intended to be driven.

To avoid beating of the driving piston and piston 23 against partition 16 when carrying out their respective back strokes, which could lead to damages of the partition 16, the driving piston 10 and the partition 16 are at their respective upper sides provided with elastic bumpers 33 and 34 respectively. Another annular elastic bumper 35 is situated at the lower side of cap 27 by which the cylindrical sleeve 25 is sealed.

The apparatus is operated in the following manner.

In the inoperative position all the movable parts are in the positions shown in FIGURES 1 and 2 in which the driving piston 10 and the piston 23 are adjacent to the rigid partition 16, with but the elastic bumpers 33 and 34 being interposed between them.

To release a Working stroke the entrance valve 6 for the compressed air is opened by actuating the finger lever 5, which causes compressed air to stream from the storage chamber 4 through channel 7 into the space 36 above the partition 16. The compressed air acts on the part of the annular surface of piston 23 which projects over the bumper 34 and lifts piston 23 into the position shown in FIGURE 3, and piston 23 at the same time collapses the spring 26. The upward motion of piston 23 causes the bar 29 to close the tongs 30 which thus arrest the workpiece 32. When the piston 23 or the wall of the bolt 22 by which the piston 23 is carried has passed the radial bore of tube 19 the compressed air is allowed to stream through this bore 20 and tube 19 into the space below partition 16 and to act on the part of the annular surface of the driving piston 10 projecting over the bumper 33, whereupon the driver 12 is moved in downward direction and a staple is issued from the magazine 13 and driven into the workpiece 32. No compressed air can stream into the space below partition 16 before the bore 20 is uncovered by piston 23 since the passages 18 are blocked by the valve balls 17. This construction insures that the compressed air does not act on the driving piston 10 and thus relase its working stroke before the piston 23 has completed the major part of its travel and has closed the tongs 30.

When driving piston 10 and piston 23 have reached their respective terminal positions they are by the springs 15 and 26 returned into their respective initial positions as shown in FIGURE 2 since the compressed air admission valve 6 is then locked and no compressed air can therefore stream into the channel 7. The air upwardly displaced by driving piston 10 is vented into the atmosphere through the now open passages 18 and the compressed air channel 7 via a suitable channel of the compressed air admission channel. The air above piston 23 leaves through the vent 28 of cap 27.

The apparatus operates in a distinct two-cycle system and reliably keeps the workpiece 32 arrested within the tongs 30 before the driving piston 10 starts its working stroke and drives the staple into it. The staples of other fasteners are therefore always properly driven into the workpiece. In the inoperative position of the apparatus the workpiece can be easily taken out of the tongs 30 as they will have released it on completion of the working stroke of the driver.

Although the present invention has been described in conjunction with one embodiment thereof it is obvious that those skilled in the art may "devise other embo'diments and combinations of parts which will fall within the scope of my appended claims.

What I claim is:

1. An apparatus for driving fastening means into a work piece comprising a cylinder, a driving piston reciprocably guided within said cylinder for driving the fasten ing means into the workpiece, an actuating piston for a clamping device, said actuating piston also being reciprocably guided within said cylinder for movement opposite to said driving piston, a rigid partition. for separation of the Working spaces of said driving piston and actuating piston from each other, a compressed air pipe ending in said cylinder above said partition and in the working space of said actuating piston, and means defining an axial channel interconnecting both said working spaces, said channel intersecting said partition and allowing admittance of compressed air to the working space of said driving piston not before said actuating piston has completed its working travel.

2. An'apparatus as described in claim 1 in which the actuating piston is of annular shape and is guided on a tube arranged in said partition in the central axis of the cylinder, said tube having an opening which on being uncovered by the actuating piston, allows compressed air to stream from the working space of the actuating piston.

into the working space of the driving piston.

3. An apparatus as described in claim 2 in which said opening of the tube has a distance from the rigid partition which equals the major part of the working travel of said actuating piston.

1 4. An apparatus in accordance with claim 2 in which said actuating piston is fastened to the lower end of a bolt which is provided with an axial bore, in which said tube is inserted and is through a rod coupled with a clamping device. 7

5. An apparatus in accordance with claim 1 inwhich said partition is provided with passage means for venting the working space of the driving piston and said passage means are sealed by check valve means.

6. An apparatus in accordance with claim 1 in which elastic bumpers are arranged between said rigid partion and the driving piston and actuating piston respectively, said bumpers being of smaller diameter than their respective pertinent pistons.

7. In a fastener driving apparatus having a driving piston movable in a first cylinder portion for driving a fastener into a workpiece. and an actuating piston movable in a second cylinder portion for actuating a workpiece clamping device, the improvement which comprises a partition between said cylinder portions, means for introducing compressed air into said second cylinder portion at one side of said partition, and air passage means extending through said partition to the opposite side thereof for connecting said cylinder portions, said air passage means being operable to admit compressed air from said second cylinder portion to said first cylinder portion only after said actuating piston has substantially completed its working stroke for actuating the clamping device.

References Cited UNITED STATES PATENTS 2,687,522 8/1954 Juilfs 227 2,854,953 10/ 1958 Osborne 9l461 2,943,327 7/1960 Juilfs 227130 3,051,135 8/1962 Smith 91-l89 PAUL E. MASLOUSKY, Primary Examiner.

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