US3208353A

US3208353A - Fastener driving apparatus

Info

Publication number: US3208353A
Application number: US269286A
Authority: US
Inventors: Oscar A Wandel
Original assignee: Duo Fast Corp
Current assignee: Duo Fast Corp
Priority date: 1963-04-01
Filing date: 1963-04-01
Publication date: 1965-09-28
Anticipated expiration: 1982-09-28

Description

p 8, 1935 o. A. WANDEL 3,203,353

FASTENER DRIVING APPARATUS Filed April 1, 1965 2 Sheets-Sheet 1 8 84- iF zgJ s4 3 6 36 d- 36 b INVENTOR.

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FASTENER DRIVING APPARATUS Filed April 1, 1963 2 Sheets-Sheet 2 INVENTOR. 2'70 05cm ,4. 144M051.

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,4rroeA/E Y6 United States Patent 3,208,353 FASTENER DRIVING APPARATUS Oscar A. Wanda], Mundelein, Ill., assignor to Fastener Corporation, Franklin Park, 111., a corporation of Illinois Filed Apr. 1, I963, Ser. No. 269,286 3 Claims. (Cl. 9l52) This invention relates to a fastener driving apparatus and, more particularly, to a fluid actuated device for driving fasteners into a workpiece.

The present invention is an improvement over pneumatically actuated fastener driving apparatus such as that described in US. Patent No. 3,043,272. In pneumatically actuated fastener driving apparatus of this type, it is highly desirable to provide a pneumatically actuated piston return mechanism which eliminates many or all of the disadvantages of previous types of apparatus. One of the disadvantages of previous types of apparatus having pneumatically operated return mechanisms is that during the return stroke of the mechanism, air containing lint or other impurities may be sucked into the moving inner parts and thus increase wear on the mechanism and decrease the operating reliability.

Accordingly, it is an object of the present invention to provide a new and improved fluid actuated fastener driving apparatus.

Another object of the present invention is to provide a new and improved pneumatically operated means for actuating a fastener driving blade in a driving apparatus.

Yet another object is to provide new and improved means for exhausting fluid from a cylinder and returning a piston in preparation for another driving stroke.

Still another object of the present invention is to provide a new and improved pneumatically operated means for actuating a fastener drive blade to drive a fastener into a workpiece and for automatically and rapidly returning the drive blade and apparatus to a position where they can be actuated to drive another fastener.

Yet another object of the present invention is to provide a new and improved pneumatically operated means for actuating a fastener driving blade having a pneumatically operated return mechanism which provides a positive means for preventing the suction of lint or other impurities into the operating mechanism of the device.

A further object of the present invention is to provide a new and improved fastener driving apparatus of the type described above which is rapid and reliable in operation, easily manufactured and assembled, simple in construction, and easily serviced.

In accordance with these and many other objects and advantages, one embodiment of the present invention comprises a fastener driving apparatus having a housing forming chamber which contains a pressurized fluid, such as compressed air. Within the chamber there is provided a cylinder having an open end exposed to the pressurized fluid in the chamber and its opposite end vented to the atmosphere. Slidably mounted within the cylinder, there is provided a piston assembly with a fastener driving blade secured to the lower end thereof and extending through the opposite end of the cylinder. Within the piston assembly, there is provided fluid actuated valve means for controlling communication between the open end and opposite end of the cylinder through the piston.

Upon actuation of the apparatus, compressed air is rapidly dumped into the open end of the cylinder, driving the piston assembly and blade rapidly downward to drive a fastener. During this downward stroke, air beneath the piston assembly in the opposite end of the cylinder is compressed slightly and forced out through the vents to the atmosphere. After the driving stroke, air pressure in the central portion of the piston assembly lifts the piston in preparation for another driving stroke. The open or upper end of the cylinder is closed and air between the upper surface of the piston assembly and the upper end of the cylinder being compressed during the upstroke of the piston passes through the exhaust valve means in the piston to the lower end of the cylinder and is vented to the atmosphere. In this manner, the lower end of the cylinder is always a little higher in pressure than the atmosphere regardless of whether the piston is on an upstroke or driving stroke and thus foreign materials will not be drawn into the lower end of the cylinder to clog or damage the mechanism.

In another embodiment of the invention, a portion of the cylinder is movable to admit compressed air into the cylinder to drive the piston downwardly on a power stroke. The piston is similar in construction to the first embodiment and is provided with exhaust valve means which allows the air trapped above the piston to pass to the lower end of the cylinder on a return stroke and out through the vents to the atmosphere.

Many other objects and advantages of the present infastener driving apparatus embodying the features of the present invention.

Referring now to FIG. 1 of the drawings, therein is illustrated one embodiment of a pneumatically operated fastener driving apparatus constructed in accordance with the features of the present invention and referred to generally as 10. The apparatus 10 includes a housing 12 having a hollow handle portion 12a which provides a compressed air reservoir to which a compressed air line (not shown) is connected. Within the housing there is provided a chamber 14 which surrounds a. cylinder 16 having an upper section 18 and a lower section 20, the upper section being of larger diameter than the lower section.

Slidably mounted within the cylinder 16 there is provided a piston assembly 22 having an upper piston 24 slidable within the upper section 18 and a lower piston 26 slidable in the lower section 20 of the cylinder. The upper and

lower pistons

24 and 26 are provided with suitable 0 rings to effect sliding seals with the cylinder wall and are integrally joined by an intermediate structure 28 which is much smaller in diameter than either of the pistons in order to provide an air cavity 30. Compressed air from the chamber 14 is continually supplied to the cavity 30 intermediate the ends of the piston as sembly by means of ports 32 positioned in the wall of the cylinder adjacent the junction of the upper and lower sections 18 and 20.

The lower end of the piston assembly 22 is provided with a resilient bumper 34 which will strike a lower end wall 36 of the chamber 14 to provide a cushioned stop for the piston assembly at the end of a drive stroke. The lower wall 36 is vented to the atmosphere as at 36a and is provided with an opening 36b to accommodate a fastener driving blade 38 which is secured to the lower portion of the piston assembly by means of a pin 40 and retaining ring 42.

Adjacent the open upper end of the section 18 of the cylinder, there is provided a main valve assembly 44 including a flexible diaphragm 46 which is movable into and out of engagement with the upper end of section 18 to control the communication between the upper end of the cylinder and the pressurized chamber 14.

The diaphragm 46 is secured between the upper end of the wall of the housing 12 that form the chamber 14 and a cap piece 48 which is secured to the housing by cap screws 48a. The cap piece 48 is provided with a chamber 50 which is coaxial with the cylinder 16 and utilizes the upper surface of the diaphragm 46 for its lower wall. The upper wall of the chamber 58 is formed by a disk 52 seated against an annular shoulder 54 provided in the cap piece. An 0 ring 56 is provided on the outer edge of the disk to provide a seal between the disk and cap piece and secure the disk in place aganist the shoulder 54.

The central portion of the disk 52 is provided with an aperture 52a and O ring 58 in order to slidingly seal against the depending stem 60 of a piston assembly 62. The assembly 62 is provided with a radially extending piston portion 64 having an O ring 66 in the edges to slidably engage the side walls of another concentric chamber 68 formed in the cap piece 48. The lower end of the stem 60 is shouldered as at 70 and threaded to accommodate a nut 72 which is utilized to secure the diaphragm 46 and an upper and lower stiffener, 74 and '76, respectively, to the stem in order that the piston assembly 62 moves in unison with the main valve assembly 44.

The upper surface of the disk 52 is provided with an annular cavity 84 which is vented to the atmosphere by means of the passage 86 in order to provide atmospheric pressure at all times on the lower surface of the piston 64. The upper surface of the piston 64 is provided with an annular cavity 88 which is positioned to overlap a larger opposed annular cavity 90 formed in the upper wall of the chamber 68. The

chambers

68 and 50 are interconnected by a passage 92 and a port 94 in order that the upper surface of the piston 64 is subject to the same pressure as the chamber 50.

Chambers

50 and 68 are connected through a passageway 96 formed in the housing 12 to a valve chamber 98 of .a trigger valve assembly 1% carried in the handle 12a. Briefly, the assembly 100 comprises a generally cylindrical body 102 secured in a cylindrical hollow boss 184 formed in the housing. The valve chamber 98 is in communication with the air reservoir in the interior of the housing 12 through a supply port 106 encircled by a valve seat 168 at the upper end of the chamber. The passageway 96 is in communication with the chamber 98 through a side port 110, and the chamber 98 is also vented to the atmosphere through a lower port 112 which is encircled by a lower valve seat 114 positioned at the lower end of the chamber.

Reciprocally movable with the chamber 98 there is provided a valve member 116 which normally is seated against the lower seat 114- closing the vent to the atmos phere. In this position compressed air from within the housing 12 flows into the chamber 98 through the supply port 106, out the side port to passageway 96 and the

chambers

50 and 68, causing the diaphragm 46 to seat against the upper end of the cylinder 16. When the valve member 116 is lifted off the lower seat 114 and moved upwardly against the upper seat 108 by means of a valve stem 118, a lost motion mechanism 120, and a trigger 122, the supply port 106 is closed and the pressure in

chambers

50 and 68 is vented to the atmosphere through the passage 92, the passageway 96, the side port 118, and the vent port 112.

When this occurs, the air pressure on the underside of the diaphragm 46 in the chamber 14 causes the diaphragm to lift off the open end of the cylinder, and air pressure from the chamber 14 is dumped into the upper end of the cylinder driving the piston assembly 22 and the drive blade 38 rapidly downward on a drive stroke.

Because of the lost motion mechanism 120 in the trigger valve assembly 100, the seating of the valve member 116 against the upper seat 108 is only momentary, and a bias spring 124 returns the valve member 116 to its normal position on the lower seat 114 regardless of the position of the trigger 122. When this happens, compressed air from the housing 12 enters the chamber 98 through the supply port 166 and proceeds out through the side port 110, passageway 96, port 94 to chamber 56 and through passage 92 to chamber 68. Since the effective downward force on the main valve assembly 44 caused by the pressure in the

chambers

68 and 50 is greater than the effective upward force on the valve assembly from air pressure in the chamber 14, the diaphragm 46 closes against the upper end of the cylinder 16 shutting off the flow of compressed air into the upper end of the cylinder from the chamber 14.

In accordance with the features of the present invention, there is provided in the piston assembly 22 an exhaust valve assembly 126. The assembly includes a ball-shaped valve member 128 which is slidable in a chamber 138 and engageable against a lower seat 132 therein. The lower end of the chamber 130 is in communication with the underside of the piston assembly by means of a passage 134, and a spring 136 normally urges the ball 128 upwardly out of engagement with the seat 132 to allow a free passage of air between the upper and lower ends of the cylinder through the passage 134. A plurality of branch passages 138 are provided to communicate between the central portion of the chamber 130 above the seat and the upper surface of the piston assembly when the ball 128 is in the position shown in FIG. 1, and a small bleed passage 139 is provided in order to communicate between the upper surface of the piston assembly and the chamber 130 below the seat 132. The crosssectional area of the bleed passage 139 is much smaller than the area of the main passage 134 for a reason hereinafter discussed.

During a power or downward stroke of the piston assembly 22 when the upper end of the cylinder 16 is under high pressure, the ball 128 is forced against the seat 132 preventing flow through the passage 134 except for the small amount of air that passes into the passage 134 through the bleed passage 139. The amount of air flowing through the bleed passage 139 during this time is so small because of the restricted size of the bleed passage that the effect on the power stroke is negligible.

After the power stroke, the diaphragm 46 closes against the upper end of the cylinder 16 and the air which is trapped in the upper end of the cylinder above the piston 24 continues to bleed out through the bleed passage 139 and the passage 134 to the lower end of the cylinder. Since the bleed passage 139 communicates with the chamber 130 below the seat 132, the pressures acting upwardly and downwardly on the ball are almost equalized so that the spring 136 can then move the ball upwardly to the position shown in FIG. 1, opening the passages 138 and allowing the entrapped air in the upper end of the cylinder to escape rapidly to the lower end of the cylinder.

The ball 128, seat 132 and spring 136 form a check valve which prevents a large amount of air from flowing from the upper to the lower end of the cylinder 16 during the power stroke. The check valve and bleed passage 139 act in conjunction to allow a rapid flow of air from the upper to the lower end of the cylinder during the return stroke to facilitate a rapid return of the piston assembly 22 in preparation for the next power stroke. From the foregoing it can be seen that pressurized air is flowing into the lower end of the cylinder 16 from the upper end during both the power and return strokes of the piston assembly thus insuring that the lint or other foreign material is not sucked into the apparatus through the

openings

36a and 36b.

Thus, the present invention provides new and improved means for pneumatically actuating a fastener driving apparatus and automatically returning the mechanism to a position preparatory to another power stroke without creating a suction which would bring foreign material into the inner parts and contribute to the deterioration and wear of the mechanism.

Another embodiment of a fastener driving apparatus characterized by the features of the present invention is illustrated in FIG. 2 and referred to generally as 210. The apparatus includes a housing 212 having a hollow handle 212a which serves as a reservoir for compressed air supplied to the apparatus by a line (not shown). The interior of the housing defines a generally cylindrical chamber 214 which is concentric with a lower cylinder 216 in which the small diameter portion 218 of a piston assembly 220 is slidably engaged. Adjacent the upper end of the lower cylinder 216 there is provided an intermediate cylindrical portion 222 which is larger in diameter than the lower cylinder and smaller than the chamber 214 and in which is slidably mounted a movable upper cylinder 224 having an internal diameter slightly larger thanthe internal diameter of the lower cylinder 216.

The upper end of the piston assembly 220 is provided with an enlarged portion 226 which is slightly larger in diameter than the lower portion 218 and which is slidable within the upper cylinder 224. The lower portion of the cylinder 224 is provided with an external annular ridge 228 having an O ring therein for sealingly slidable engagement with the walls of the intermediate cylindrical surface 222. A guide ring 230 is provided in the chamher 214 just above the intermediate cylindrical surface 222 to guide the sliding movements of the upper cylinder 224. The upper end of the chamber 214 is provided with a threaded cap 232 having a valve assembly 234 carried thereon including an enlarged valve disk 236 for engagement with the upper end of the upper cylinder 224 and another disk 238 for engagement with an internal shoulder 224a on the upper cylinder. Upon upward movement of the upper cylinder 224 into engagement with the disks of the valve disk assembly 234, communication between the upper end of the cylinder and the chamber 214 is cut off, while upon a downward movement of the cylinder 224 away from the disks communication is re-established.

In order to control the flow of compressed air into the area within the intermediate cylindrical surface 222, there are provided a safety slide valve 240 and a trigger valve 242. The slide valve 240 includes a plunger 244 which slides in a bore 246, the upper end of which is in communication with the air reservoir within the housing 212. Below the upper end of the bore 246 there is provided a side passage 248 which communicates with the area within the intermediate cylindrical surface 222. On the opposite wall of the bore 246 is a passage 250 which communicates with a central valve chamber 252 of the trigger valve 242. The upper part of the chamber 252 is in communication with the air reservoir within the housing 212 through a passage 254 and the lower surface of the chamber 252 is provided with an annular seat ring 256 which encircles a vent passage 258 to the atmsophere. Within the vent passage 258 there is provided a fluted actuating pin 260 the lower end of which is adapted for engagement by a pivoted trigger 262. When the trigger is depressed, the upper end of the fluted pin 260 raises a ball member 264 off the seat 256 against the opening of the passage 254 closing it off, while permitting air from the passage to flow out the passage 258 to atmosphere through the flutes in the pin. After the trigger is released, the ball 264 will again seat against the seat 256 and open communication between the passages 254 and 250.

The upper end of the valve rod 244 is tapered so that when in the safety position, as shown in FIG. 2, the bore 246 is in communication between the air reservoir and passage 248. Thus, high pressure air enters the area adjacent the intermediate cylindrical surface 222 and moves the upper cylinder 224 upward into contact with the upper valve assembly 234 and additionally moves the piston assembly 220 upwardly toward the top end of the 6 upper cylinder 224. With the safety valve 240 in the position shown in FIG. 2, the apparatus will not fire regardless of whether the trigger is depressed.

When the safety valve is moved upward until an annular groove 244a in the plunger 244 is positioned opposite the passages 248 and 250, the trigger valve 242 is effective to operate the apparatus. The plunger 244 is moved upwardly into the operative position when a nosepiece 268 of the fastener drive track is positioned against a workpiece thus moving a safety arm 270 upwardly which is connected to the plunger 244.

Adjacent the lower end of the cylinder 216 there is provided a magazine 272 containing a stick of fasteners 274 to be driven by a fastener driving blade 276 which is slidably received in a drive track 278 in the nosepiece 268. The upper end of the drive track is in communication with the lower end of the cylinder 216 by means of a port 280 through which the drive blade passes, and the cylinder 216 is also vented to the atmosphere through a side port 282.

The upper end of the drive blade 276 is secured to the piston assembly 220 by means of a plug unit 284 which is secured within a recess 286 in the lower end of the piston by means of a cap screw 288. The bottom end of the lower cylinder 216 is provided with a resilient bumper 290 to cushion the downward stroke of the piston.

In accordance with the features of the present invention the piston assembly 220 is provided with an exhaust valve assembly 292 which is similar in construction and operation to the valve assembly 126 shown in the embodiment of FIG. 1. The assembly 292 includes a ball 294 which is slidable within a chamber 296 having a seat 298. A spring 300 normally biases the ball toward the upper end of the chamber and a pair of branch passages 302 communicate between the upper surface of the piston assembly 220 and the chamber 296 just above the seat 298. The lower end of the chamber 296 is in communication with the lower end of the cylinder 216 by means of a passage 304 in the piston assembly and a passage 306 in the cap screw 288. A small bleed passage 308 communicates between the upper end of the piston assembly 220 and the chamber 296 below the seat 298.

During a driving stroke of the apparatus, high pressure air acting against the upper surface of the piston assembly 220, moves it rapidly downward. This air pressure seats the ball 294 against the seat 298 closing off the branch passages 302; however, a small amount of air passes through the bleed passage 308, and

passages

304 and 306 into the lower end of the cylinder 216. The amount of air passing through the bleed passage on the power stroke is so small that it has a negligible effect on the power of the stroke.

After the power stroke, the upper cylinder 224 moves upwardly against the disks of the valve assembly 234 shutting off the flow of pressurized air into the upper cylinder. Air which is trapped in the upper cylinder flows through the bleed passage 308,

passages

304 and 306 to the lower cylinder 216. Since the bleed passage 308 is in communication with the chamber 296 below the seat 298, the pressures acting upwardly and downwardly on the ball 294 are almost equalized, allowing the spring 300 to move the ball away from the seat 298 to the position shown in FIG. 2. When this happens the branch passages 302 are opened and the air in the upper cylinder 224 can pass rapidly to the lower cylinder 216 thus allowing the rapid upward movement of the piston assembly 220 on the return stroke.

The ball 294, seat 296 and spring 300 act as a check valve preventing a large flow of air from the upper cylinder 224 to the lower cylinder 216 during the power stroke. The check valve and bleed passage 308 act in conjunction to allow a rapid flow of air from the upper to lower cylinder on the return stroke in order to provide a rapid return of the piston assembly in preparation for the next power stroke. Again it should be noted that during both the power and return strokes air is flowing into the lower cylinder 216 from the upper cylinder 224 thus insuring that lint or other foreign materials are not drawn into the mechanism through the

openings

280 and 282.

While there have been illustrated and described several embodiments of the fastener driving apparatus of the present invention, it will be understood that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A fastener driving apparatus comprising a housing defining a chamber adapted to contain a compressed fluid, cylinder means having an open end adapted for controlled exposure to said compressed fluid and an opposite end having a cross-section smaller than said open end and vented to the atmosphere, piston means slidably mounted in said cylinder means movable between said ends, said piston means having a first piston slidable in said cylinder means adjacent said open end, a second piston slidable in said cylinder means adjacent said opposite end and an intermediate portion joining said first and second pistons, means for providing continual exposure of said intermediate portion to said compressed fluid, and fluid actuated valve means carried by said piston means for controlling communication between the open end and said opposite end of said cylinder means, said valve means including passage means extending through said piston means defining a seat therein, a valve member mounted within said passage means movable into and away from engagement with said seat, bias means for normally biasing said valve member away from said seat and a bleed passage of smaller cross section than said passage means, said bleed passage communicating between the open end of said cylinder means and said passage means and bypassing said valve member and seat.

2. A fastener driving apparatus comprising a housing defining a chamber adapted to contain compressed fluid, cylinder means having an open end adapted for exposure to the compressed fluid in said chamber and an opposite end in continual open communication with the atmosphere, first valve means adjacent the open end of said cylinder means and cooperating therewith to open and close communication between said chamber and said cylinder means, piston means in said cylinder means movable therein between said ends, passage means formed in said piston means communicating between opposite ends thereof to permit fluid flow through said piston means between the ends of said cylinder means, second valve means in said passage means, said second valve means fluid operated to close said passage means when said first valve means is opened to expose the open end of said cylinder means to said compressed fluid and means in said piston means for bypassing fluid around said second valve means between said open end and said opposite end of said cylinder means.

3. Apparatus defined in claim 2 wherein said last mentioned means includes a bleed passage form in said piston means of smaller cross-section than said passage means, sad bleed passage being in communication with the open end of said cylinder means and said passage means and by-passing said valve means.

References Cited by the Examiner UNITED STATES PATENTS 343,569 6/86 Cooper 91268 2,709,420 5/55 Fullwood 91--401 X 2,901,977 9/59 Synder 91442 2,932,280 4/60 Vielmo 91-442 3,043,272 7/62 Wandel 9142() 3,106,136 10/63 Langas 91-468 FRED E. ENGELTHALER, Primary Examiner.

SAMUEL LEVINE, Examiner.

Claims

2. A FASTENER DRIVING APPARATUS COMPRISING A HOUSING DEFINING A CHAMBER ADAPTED TO CONTAIN COMPRESSED FLUID, CYLINDER MEANS HAVING AN OPEN END ADAPTED FOR EXPOSURE TO THE COMPRESSED FLUID IN SAID CHAMBER AND AN OPPOSITE END IN CONTINUAL OPEN COMMUNICATION WITH THE ATMOSPHERE, FIRST VALVE MEANS ADJACENT THE OPEN END OF SAID CYLINDER MEANS AND COOPERATING THEREWITH TO OPEN AND CLOSE COMMUNICATION BETWEEN SAID CHAMBER AND SAID CYLINDER MEANS , PISTON MEANS IN SAID CYLINDER MEANS MOVABLE THEREIN BETWEEN SAID ENDS, PASSAGE MEANS FORMED IN SAID PISTON MEANS COMMUNICATING BETWEEN OPPOSITE ENDS THEREOF TO PERMIT FLUID FLOW THROUGH SAID PISTON MEANS BETWEEN THE ENDS OF SAID CYLINDER MEANS, SECOND VALVE MEANS IN SAID PASSAGE MEANS, SAID SECOND VALVE MEANS FLUID OPERATED TO CLOSE SAID PASSAGE MEANS WHEN SAID FIRST VALVE MEANS IS OPENED TO EXPOSE THE OPEN END OF SAID CYLINDER MEANS TO SAID COMPRESSED FLUID AND MEANS IN SAID PISTON MEANS FOR BYPASSSING FLUID AROUND SAID SECOND VALVE MEANS BETWEEN SAID OPEN END AND SAID OPPOSITE END OF SAID CYLINDER MEANS.