US3288339A

US3288339A - Pneumatically operable driving device for driving nails, staples, and the like

Info

Publication number: US3288339A
Application number: US362119A
Authority: US
Inventors: Bade Heinz Emil
Original assignee: Joh Friedrich Behrens AG
Current assignee: Joh Friedrich Behrens AG
Priority date: 1963-04-27
Filing date: 1964-04-23
Publication date: 1966-11-29
Anticipated expiration: 1983-11-29
Also published as: DE1277166B

Description

Nov. 29, 1966 H. E. BADE 3,288,339

PNEUMATICALLY OPERABLE DRIVING DEVICE FOR DRIVING NAILS, STAPLES, AND THE LIKE Filed April 25, 1964 3 Sheets-Sheet 1 3 6 30 5 44 3 a 3d 36 32 39 2 11 72 29 I3 13! 6 7a 2 I 38 6d 4 27 8 10 47 78 Nov. 29, 1966 H. E. BADE 3,

PNEUMATICALLY OPERABLE DRIVING DEVICE FOR DRIVING NAILS, STAPLES, AND THE LIKE Filed April 23, 1964 5 Sheets-Sheet 2 is ,1? 62 67 A IMMMI 65 Nov. 29, 1966 H. E. BADE 3,288,339

PNEUMATICALLY OPERABIJE DRIVING DEVICE FOR DRIVING NAILS, STAPLES, AND THE LIKE Filed April 23, 1964 5 Sheets-Sheet 5 /wz ,,,/Ll9

United States Patent O 9 Claims. 61. 227-130 The present invention relates to a pneumatically operable driving device for driving nails, staples and the like into work pieces of various types. The invention is based on a driving device of the above-mentioned general type in which a piston having the driver connected thereto, is, following the completion of its working stroke, returned to its starting position by the effect of air.

With most heretofore known devices of the type involved, the piston is returned to its starting position by compressed air acting upon the driver side of the piston, i.e. that side which faces in the direction of the driving stroke. In contrast thereto, with the arrangement according to the present invention, the piston is returned to its starting position by a suction effect upon the top end face of the piston, i.e. that which is remote from the driver. More specifically, the return is brought about by an ejector effect exerted by the operating compressed air in an ejector nozzle, upon the air above the top end face of the piston.

It is an object of the present invention to provide a compressed air operable device for driving fastening means such as nails, staples and the like into a workpiece in which the return of the working piston to its starting position will be effected without the necessity of an air accumulator or air storage means.

It is another object of this invention to provide a compressed air operable driving device as set forth above, in which no air cushion can form which might interfere with the driving force of the piston.

Still another object of this invention consists in the provision of a device as outlined in the preceding paragraphs, which will make it possible to mount all control elements in the head portion of the working cylinder so that they will not interfere with the working members proper of the device.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGURE 1 diagrammatically illustrates a cross-section through a driving device according to the present invention showing said driving device in its resting or starting position;

FIGURE 2 shows the arrangement of FIGURE 1 but with the driving piston occupying a position during its driving stroke;

FIGURE 3 shows the device of FIGURE 1 but with the driving piston on its return stroke;

FIGURE 4 shows a slight modification of the righthand central portion of FIGURE 1;

FIGURE 5 shows a modified detail for holding the driver piston in its retracted position.

In conformity with the present invention, the above mentioned ejector effect is produced by a valve arranged in the cylinder head of the device and adapted to be actuated by the operating compressed air which is controlled by a trigger. At the same time, the said valve controls the inlet of compressed air into the working cylinder. Furthermore, in conformity with the present invention, a second valve is provided which controls the supply of compressed air to the ejector nozzle.

Referring now to the drawing in detail, and FIG, 1 thereof in particular, the device illustrated therein comprises a housing 1 having a handle section 2 for handling the device. The housing 1 is, in a manner customary with devices of this type, provided with connecting means (not shown) for connection to a pressure source and is hollow so as to provide a conduit 4 for conveying compressed air of operation from a compressed air supply source to the interior of the device. Housing 1 has screwed thereinto a cylinder head 5 with a cover 6. Furthermore fixedly mounted in housing 1 is a cylinder 7 having reciprocably mounted therein a piston 8. Piston 3 carries a driver 9 which is held in the piston by means of a pin 19.

The cylinder head 5 has a cylindrical bore 11 therein in which is reciprocably mounted a first control member 12 henceforth called head valve. This head valve has an extension 12a which slidably engages a bore 5a in the cylinder head 5. The head valve 12 has furthermore a piston section 12b reciprocably mounted in a bore 13 of the housing. The bottom portion of the head valve 12 is adapted sealingly to engage the tapered portion 7a of cylinder 7 and is also adapted to engage the top surface 8a of piston 8.

The arrangement according to the present invention as shown in the drawing furthermore comprises a second control member 13 in the form of an ejector valve member which is reciprocably arranged in a bore 14 of the head valve 12, for a purpose which will be explained.

further below.

The arrangement according to the present invention also comprises a third control member 15 adapted to be actuated by a manually operable trigger 16. Near said control member 15 there is provided a fourth control member 17 which is reciprocable in a bore 18 of a sleeve 19 inserted into the housing 1. The said control member 17 has connected thereto one end portion of a link member 20 the other end portion of which embraces the mouthpiece 21 of the device according to the present invention The device illustrated in FIG. 1 occupies its starting position according to which compressed air in passage 4 through a small bore 22 communicates with a passage 23 which latter, however, is closed by control member 17. The compressed air in passage 4 also acts in bore 18 upon control member 17 and through bores and

passages

24, 25, 26, 27, 28 and 29 communicates with bore 11 in cylinder head 5 so as to act upon the top surface 30 of head valve 12 thereby causing the bottom portion 120 of the head valve 12 sealingly to engage the tapered portion 7a of cylinder 7. The compressed air in passage 4 also acts upon an annular surface area 31 of the head valve piston section 12b. However, since this annular area 31 is less than the top surface 30 of head valve 12, the pressure acting on the annular area 31 can at this 3 time not lift head valve 12 off the tapered portion 7a of cylinder 7.

The device is, of course, provided with a magazine M which in customary manner feeds a staple, nail or the like into the path of the driver 9 to be driven into a work piece by the latter with the next following driving stroke.

Operation Assuming that all parts of the device occupy the posi tion shown in FIG. 1 and that it is now desired to drive a staple, nail or the like fed from the magazine into the path of driver 9, into a work piece, the operator places the mouthpiece of the device on the work piece and pulls the trigger 16 so that control member 15 interrupts communication between passage 4 and passage 23 through bore 22. When the mouthpiece 21 of the device is plamd on a work piece after the trigger 16 has been pulled, link 20 will move control member 17 upwardly with regard to the drawing whereby the control member 17 will close off communication between passage 4 and bore 24 while establishing, by means of grooves 17a, communication between passage 23 and bore 24. As a result thereof, the air under pressure in cylinder bore 11 escapes into the atmosphere through

passages

29, 28, 27, 26, 24 and 23 and one or more longitudinal grooves 15a in the periphery of control member 15. Consequently, the compressed air acting on the annular surface 31 of head valve 12 is now able to lift head valve 12 so that the bottom portion 120 of the head valve 12 is lifted off the piston 8 and the latter, due to the compressed air acting thereupon, is instantaneously moved downwardly in driving direction thereby exerting a strong driving push upon the fastening means and driving the same into the respective work piece.

FIG. 2 shows the device according to the present invention during its driving stroke. It will be noted that in this position the head valve 12 has its tubular extension 12a in engagement with the sealing surface 33a of a sealing member 33 which is held in a holding member 34 riveted or otherwise connected to cover 6 mounted on and connected to cylinder head 5. Cover 6 together with cylinder head confines radially extending discharge opening 36 (one only being shown). Due to this engagement of tubular extension 12a with the sealing surface 33a of sealing member 33, the chamber 37 confined by cover 6 and cylinder head 5 and thus the discharge openings 36, are closed off from communication with a conical bore 12d in extension 12a. In this connection, it may be mentioned that by the magnitude of the radial bores 36, it is possible to determine the speed of the return of the piston 8 in conformity with the principle of the Laval nozzle. These bores 36 may be provided with butterflie or other valve members for varying the effective cross-section of bores 36.

As will be evident from the drawing, the head valve 12 is provided with a plurality, for instance three evenly distributed passages 38 which establish communication between the conical bore 12d and the bottom surface of the bottom portion 120 of head valve 12. It will thus be appreciated that immediately head valve 12 is lifted off piston 8, compressed air passed from passage 4 between piston 8 and bottom portion 12c of head valve 12 rushes through

passages

38 and 39 into bore 32 and acts upon the top surface 13a of valve member 13. Inasmuch as the top surface 13a of valve member 13 is greater than the bottom surface thereof, valve member 13 is pushed downwardly into the position shown in FIG. 2 so as to rest upon an insert member 41 threadedly engaging head valve 12 and secured thereto in any convenient manner. In this lower position of valve member 13 that section of bore 14 which is above the top surface 13a of valve member 13 is, through a series of passages 42 evenly distributed along a circular line in head valve 12, in communication with compressed air conveying passage 4. By means of an insert 43, the upper portion of bore 14 is formed into a pressure increasing nozzle. In other words, the insert 43 forms a nozzle body.

By exchanging the nozzle body 43 by a differently shaped one, the nozzle effect may be varied in conformity with different requirements. If, on the other hand, one and the same nozzle effect is to be retained, it is, of course, possible, instead of providing the nozzle insert body 43, to provide the head valve 12 with a corresponding nozzle-shaped extension integral therewith.

It will be appreciated that the nozzle has an ejector effect upon the air conveyed thereto through

passages

38 and 39 as soon as the air is flowing. Since after release of trigger 16, and lifting the device off the work piece,

valve members

15 and 17 return to their FIG. 1 position, air under considerable pressure coming in from passage 4 and passing through

passages

24, 25, 26, 27, 28 and 29 into cylinder bore 11 acts upon the upper end face of head valve 12 and moves the same into its closing position, shown in FIG. 3. As a result thereof, the slit-like passages 44 in cylinder head 5 between the tubular extension 12a of the head valve 12 and the sealing surface 33a of sealing member 33 are opened, and the ejector flow may escape into the atmosphere through chamber 37 and openings 36. In view of the ejector effect, the expanded air is drawn from the interior of cylinder 7 through passages 38, and the thus created suction effect pulls piston 8 back to its upper starting position, shown in FIG. 1, and retains it in said retracted position.

If desired, however, the retaining of the piston in its retracted position by the above mentioned suction effect may be greatly aided by a piston-head valve construction as illustrated in FIG. 5. In FIG. 5, the head valve is designated with the reference numeral and is provided with a dovetailed circular groove 61 having an O-ring 62 therein for sealing engagement with the adjacent end face of cylinder 7. The driver piston 63 having the driver 9 connected thereto, e.g. in the manner described in connection with FIG. 1, has a recess 64 with an outwardly flaring surface 65 for cooperation with a correspondingly tapering surface 66a of an elastic body 66, e.g. of polyurethane, which is firmly clamped against head valve 60 by means of a holding member 67 having a threaded portion 68 threadedly engaging headvalve 60. It will thus be evident that when piston 63 reaches its retracted position, it so to speak wedges itself upon said elastic body 66. This arrangement is somewhat similar to the arrangement in my US. Patent No. 3,128,468 of April 14, 1964.

Preferably, however, the insert member 41 may either be designed as a permanent magnet, in which instance valve member 13 is of non-magnetic material, or member 41 may have a permanent magnet inserted thereinto. Such permanent magnet will be dimensioned so as to be strong enough to retain piston 8 in its retracted position when no compressed air acts upon its top surface 8a, but will release piston 8 as soon as head valve 12 is lifted from cylinder portion 7a and compressed air from passage 4 can enter a gap formed between the bottom portion of head valve 12 and the top surface 8a, because of member 41, and thus can act upon piston 8. Furthermore, the compressed air may act upon the annular top surface of the sealing ring of piston 8, between the piston and cylinder 7. The employment of a permanent magnet in this connection has the great advantage that when piston 8 passes through the last phase of its retraction stroke, the magnet exerts a positive and strong pull on the piston so as definitely to return the same to its starting position. In this position piston 8 acts upon valve member 13 and positively moves the same into its closing position (FIG. 1) in which it closes the bore 32 as well as the passages 42. This cuts off the supply of compressed air from passage 4 and finishes the ejection effect.

Inasmuch as the total cross-section of the passages 38 in the head valve 12 is greater than the total of the crosssections of passages 42, it will be appreciated that prior to the start of the ejector effect, any compressed air in cylinder 7 may escape into the atmosphere through

passages

38 and 36.

In order to prevent air seeping into the chamber 48 of head valve 12 and chamber 14 of valve member 13 from interfering with the movement of said members in the course of time, head valve 12 is provided with passages 46, 47 communicating with chamber 48 which latter communicates through a passage 49 with the atmosphere, so that air which normally would accumulate in this chamber may be discharged.

The above-described arrangement of the control member 17 and its actuation by link 20 not only serves for purposes of insuring the safety of the device but may also be used for actuating the device. To this end, after the trigger 16 has been pulled, the mouth 21 of the device is placed on the work piece into which a fastening means is to be driven. The thereby effected displacement of link 20 in upward direction (FIG. 2) will, through the intervention of control member 17 interrupt communication between passage 4 and

passages

24, 25, 26, 27, 28 and 29 to the bore 11 so that the latter will, through bore 23 and grooves a of control member 15 be vented in reverse direction. As a result thereof, head valve 12 is by compressed air lifted into its opening position, and the working stroke of piston 8 is initiated. In this way the working operation of the device can be controlled merely by placing the same onto the work piece portion into which a fastening means is to be driven. This greatly facilitates and speeds up driving operations when a great number of successive driving operations, for instance along a line, are to be effected.

If it should happen that for certain working operations, the lower end of the link handicaps the working operations, link 20 may according to the present invention be easily removed from the device without any special tools. To this end, it is merely necessary to slightly loosen pin 51 which normally holds the upper end of link 20 in connection with control member 17, and to pull out the said upper end of link 20. The link 20 can then be completely removed.

Control member 17 can then be operated manually by pressing that end portion 52 which protrudes from the laterally protruding flange 53 of housing 1 upwardly until the lower surface 54 of control member 17 is flush with the bottom surface of said flange 53. It will be appreciated that the height of that portion 52 which protrudes from flange 53 downwardly corresponds to the upward stroke Which is normally effected by link 20 when the mouth 21 of the device is placed upon a work piece into which a driving means is to be driven.

The device according to the present invention may, if desired, be simplified in conformity with the arrangement of FIG. 4 according to which the control member 17 has been omitted and the actuation of the device is effected merely and solely by actuating the trigger 16.

As will be evident from the preceding description, the arrangement according to the present invention makes it possible reliably and quickly to retract the working piston to its starting position and to do this by means of a centrally arranged control mechanism which is acted upon by the compressed air of operation only without employment of an air accumulator. The main part of this control mechanism is the above mentioned head valve 12 which at the same time controls the working stroke while from the very start the maximum driving force acts upon the piston. Inasmuch as at the lower end of the working cylinder 7 there are absolutely no control or closing members, it will be obvious that no air cushion can form here which could possibly reduce the driving force of the piston. The air driven ahead of the working piston during the driving stroke can in a continuous manner and without restriction immediately escape toward the outside. All of the control members of the device can be arranged in the head portion of the device so that the working elements proper, namely the piston and the driver, can be arranged locally completely independently from the control mechanism. Such an arrangement permits numerous practical embodiments of the invention and any desired dimensioning of the piston stroke so that with the device according to the present invention it will be possible to drive fastening means of any desired length into a work piece.

It may be summarized that the above advantageous elfects according to the present invention can be realized with the above mentioned three control members, namely the control member 15, the head valve 12 and the ejector valve member 13.

According to the present invention, the apparatus may be supplemented by a fourth control device which may be arranged between the control member 15 and the head valve 12 and acts as a kind of safety mechanism so as to make sure that the driving of a fastening means into a work piece will be effected only when the device has been placed upon the work piece.

It is, of course, to be understood that the present invention is, by no means, limited to the particular constructions shown in the drawings but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. In a compressed air operable driving device for driving fastening means into a work piece: a housing, a cylinder in said housing, a driver-carrying piston reciprocable in said cylinder from a first position representing the retracted position of said piston to a second position representing an advanced driving position, and vice versa, said piston having a main surface adapted when subjected to the action of compressed air to drive said piston in a working stroke performing direction, nozzle means provided in said housing and having an inlet and an outlet, first conduit means communicating with said inlet and adapted to be connected to a source of compressed air, second conduit means leading from said outlet to the atmosphere, and third conduit means establishing communication between said outlet and said main surface whereby in response to compressed air passing from said first conduit means through said nozzle means to said second conduit means a suction effect is created in said third conduit means and on said piston so as to return the same to its retracted position.

2. A compressed air operable driving device, which includes: first conduit means having a first section adapted to be connected to a source of compressed air and having a second section with an outlet leading into the atmosphere, a reciprocable driver-carrying piston for driving fastening means into a work piece, said piston having a main surface adapted when subjected to the action of compressed air to drive said piston in a working stroke performing direction, first control means including ejector nozzle means interposed between said first and second sections and operable to control communication between said first and second sections through said ejector nozzle means, said first control means also being operable to control communication between said first section and said main surface, second conduit means establishing communication between said main surface and said second section near said ejector nozzle means whereby a suction effect is produced on said main surface in response to the flow of compressed air from said first section through said ejector nozzle means to said second section, said first control means having first surface means arranged in continuous communication with said first section and facing toward said piston, said first control means also having second surface means provided with a greater effective area than said first surface means and facing away from said piston, and second control means movable into a first position to establish communication between said second surface means and the atmosphere and also movable into a second position to establish communication between said first section and said second surface means.

3. In a compressed air operable driving device for driving fastening means into a work piece: a housing having a lower section provided with guiding means adapted to guide fastening means into a work piece and also adapted to be placed on a work piece into which the fastening means is to be driven, said housing also comprising a top section and an intermediate section between said lower section and said top section, said housing furthermore including a handle portion with first passage means therein adapted to be connected to a source of compressed air, a cylinder arranged in said intermediate section and open at both ends, a driver-carrying piston reciprocable in said cylinder from a first position representing the retracted position of said piston to a second position representing an advanced driving position, and vice versa, said piston having a main surface adapted when subjected to the action of compressed air to drive said piston in a working stroke performing direction, a first control member arranged in said top section and movable from a first position in which it closes the adjacent open end of said cylinder to a second position in which it is spaced from said open end of said cylinder to thereby establish communication between said first passage means and said main surface of said piston and to permit compressed air to pass from said first passage means into said cylinder for causing said piston to perform a working stroke, said first control member also being movable from said second position to said first position for closing said open end of said cylinder, an ejector nozzle provided in said first control member and having an inlet and an outlet, said first control member being provided with a bore communicating with said nozzle inlet, second passage means leading from said first passage means into said bore, a second control member reciprocable in said bore and movable from a first position in which communication is established between said first passage means and said inlet through said second passage means and said bore to a second position in which said last mentioned communication is interrupted, said second control member also being movable from said second position to said first position, third passage means leading from said outlet to the atmosphere, said first control member being operable in its second position to interrupt communication of said nozzle outlet with said third passage means and to permit said last communication when said first control member occupies its first position, and fourth passage means establishing communication between said outlet and said main surface whereby in response to the compressed air passing from said first passage means through said nozzle to said third passage means a suction efiiect is created in said fourth passage means and on said piston so as to return the same to its retracted position, said second control member being movable automatically to its second position in response to said driver-carrying piston moving through the last phase of its return stroke to said retracted position.

4. In a compressed air operable driving device for driving fastening means into a work piece: a housing, a cylin- .der mounted in said housing, a driver-carrying piston reciprocable in said cylinder from a first position representing the retracted position of said piston to a second position representing an advanced driving position, and vice versa, said piston having a main surface adapted when subjected to the action of compressed air to drive said piston in a working stroke performing direction, said housing having a section with first passage means therein adapted to be connected to a source of compressed air, first reciprocable control means movable into a first position for establishing communication between said first passage means and said main surface of said piston to thereby cause compressed air from said first passage means to flow to said main surface for causing said piston to perform a working stroke, said first control means also being movable into a second position for interrupting communication between said first passage means and said main surface of said piston, nozzle means associated with said first control means and having an inlet and an outlet, second passage means adapted to convey compressed air from said first passage means to said inlet, second reciprocable control means movable from a first position in which it permits communication between said first passage means to said inlet through said second passage means to a second position in which it interrupts said communication, said second control means also being movable from said second position to said first position, third passage means leading from said outlet to the atmosphere, said first control means being operable in said first position to prevent communication of said outlet with the atmosphere and in said second position of said first control means to permit said last mentioned communication, and fourth passage means establishing communication between said main surface and said outlet, said second control means being movable to its second position by said piston on the return stroke thereof.

5. An arrangement according to claim 4, in which said first control means is provided with a first piston area adapted when subjected to compressed air to move said first control means into its second position and in which said first control means is also provided with a second piston area opposite to and smaller than said first piston area and in continuous communication with said first passage means, conduit means communicating with said first piston area, and third control means communicating with said conduit means and operable to move into a first position for establishing communication between said first passage means and said first piston area through said conduit means and also being movable into a second position to interrupt said last mentioned communication and to vent said conduit means to the atmosphere.

6. An arrangement according to claim 1, which includes a reciprocable control member carrying said nozzle means and controlling communication between said first conduit means and said main surface of said piston, said control member being reciprocable in the direction of reciprocation of said piston, said control member and said driver-carrying piston having adjacent surface portions provided with conical surface areas adapted frictionally to interengage each other in the retracted position of said piston.

7. An arrangement according to claim 4, in which said first control means is provided with a first piston area adapted when subjected to compressed air to move said first control means into its second position and in which said first control means is also provided with a second piston area opposite to and smaller than said first piston area and in continuous communication with said first passage means, conduit means communicating with said first piston area, third control means communicating with said conduit means and movable into a first position for establishing communication between said first passage means and said conduit means and also movable into a second position for interrupting said last mentioned communication and venting said conduit means to the atmosphere, and fourth control means interposed in said conduit means between said third control means and said first piston area, said fourth control means being movable from a position in which it establishes communication between said conduit means and said first passage means while by-passing said third control means into a position in which it interrupts said last mentioned communication and establishes communication between one section of said conduit means communicating with said first piston area and the other section of said conduit means leading to said third control means.

8. An arrangement according to claim 7, in Which said compressed air operable device has a placement part to be placed on the Work piece into which fastening means are to be driven thereby, and link means operatively connected to said placement part and linked to said fourth control means for actuating the same in response to the placing of said placement part upon a work piece into which a fastening means has to be driven.

9. An arrangement according to claim 1, which in- 21c means and controlling communication between said first conduit means and said main surface of said piston, said control member being reciprocable in the directracted position thereof.

No references cited.

cludes a reciprocable control member carrying said noz- 10 GRANVILLE Y. CUSTER, 1a., Primary Examiner.

Claims

1. IN A COMPRESSED AIR OPERABLE DRIVING DEVICE FOR DRIVING FASTENING MEANS INTO A WORK PIECE: A HOUSING, A CYLINDER IN SAID HOUSING, A DRIVE-CARRING PISTON RECIPROCABLE IN SAID CYLINDER FROM A FIRST POSITION REPRESENTING THE RETRACTED POSITION OF SAID PISTON TO A SECOND POSITION REPRESENTING AN ADVANCED DRIVING POSITION, AND VICE VERSA, SAID PISTON HAVING A MAIN SURFACE ADAPTED WHEN SUBJECTED TO THE ACTION OF COMPRESSED AIR TO DRIVE SAID PISTON IN A WORKING STROKE PERFORMING DIRECTION, NOZZLE MEANS PROVIDED IN SAID HOUSING AND HAVING AN INLET AND AN OUTLET, FIRST CONDUIT MEANS COMMUNICATING WITH SAID INLET AND ADAPTED TO BE CONNECTED TO A SOURCE OF COMPRESSED AIR, SECOND CONDUIT MEANS LEADING FROM SAID OUTLET TO THE ATMOSPHERE, AND THIRD CONDUIT MEANS ESTABLISHING COMMUNICATION BETWEEN SAID OUTLET AND SAID MAIN SURFACE WHEREBY IN RESPONSE TO COMPRESSED AIR PASSING FROM SAID FIRST CONDUIT MEANS THROUGH SAID NOZZLE MEANS TO SAID SECOND CONDUIT MEANS A SUCTION EFFECT IS CREATED IN SAID THIRD CONDUIT MEANS AND ON SAID PISTON SO AS TO RETURN THE SAME TO ITS RETRACTED POSITION.