US 3776444 A
A loop type fastening mechanism which utilizes an air operated plunger which pushes the fastener into engagement with the support.
Claims available in
Description (OCR text may contain errors)
United States Patent Kuehn et al. Dec. 4, 1973 LOOP FASTENER GUN ASSEMBLY 2,399,933 ""'8[1'959 Dalton ..'.;.......;J;'."227 130 2 983 255 5/1961 Crooks et al. 227/130  Inventors: Donald E. Kuehn, Bay Village; John 498l 6 1964 ul 2 Keith Lyon, Lorain, both of Ohio Demetrakopo 05 et al 2 7/149  Asslgneez TRW Inc., Cleveland, OhlO 4 Mind}; v Custer .Ji. 7.  Filed: June 21, 1971 Attorney-Allen D. Gutchess, Jr.
 Appl. No.: 154,936
 ABSTRACT  CL 227,130 A loop type fastening mechanism which utilizes an air 51 lm. Cl..II:II::::::::::::::.III;2325c 1/04 Phmge whih Pushes the fastener 58 Field of Search 227/130, 149 gagemem the  References Cited 5 Claims, Drawing UNITED STATES PATENTS 2,888,679 6/1959 letetssen et al 227/130 1/ x/ m \kfi LMUU u Fuuuuuum 72 PATENTEBUEC 4197a FIG. 2
INVENTORS DONALD E. KUEHN B J. KEITH LYON ATTORNEY LOOP FASTENER GUN ASSEMBLY BACKGROUND OF THE INVENTION In the past the gasket liner and cover of refrigerators have been fastened together by using screws. More recent, the use of loop type panel fasteners have become popular and these have been attached through the use of hand tools such as a hammer. This method of engagement is extremely inefficient causing damage to either the liner or the cover and also creating irregularity in the engaement of the difierent parts. The gun or tool disclosed herein, due to the use of stored energy, pushes the fastener into engagement with the liner, gasket and cover. The gun is extremely safe to handle since the push type of operation will not drive a fastener into the free hand of an operator.
SUMMARY OF THE INVENTION This is a loop type fastening system utilizing an air gun which stores the energy created by the air and then releases it in a pushing type of operation rather than in an impact type of operation. The gun automatically inserts and reloads itself at a rate of approximately 40 per minute with continuous operation of up to 2,000 or 3,000 pieces depending on the type of external reservoir.
An object'of the present invention is to provide an efficient automatic fastening system for loop type fasteners. g
A further object of the present invention is to provide an automatic fastening tool which does not utilize an impact type engagement.
A still further object of the present invention is to provide a loop fastener gun assembly which utilizes a sear type trigger mechanism for releasing the piston and also for deactivating an electrical circuit. A still further object of the present invention is to provide a trigger mechanism which releases the piston and simultaneously engages the plunger of an electrical switch.
BRIEF DESCRIPTION OF THE DRAWINGS actuation of the trigger mechanism;
FIG. 3 is a section of the gun shown in FIGS. 1 and 2 showing the gun after the trigger mechansim has been activated;
FIG. 4 is a section taken on line 4-4 of FIG. 1; and FIG. 5 is a side perspective view of the fastener.
DESCRIPTION OF THE PREFERRED I EMBODIMENT In the drawing there is shown a pneumatic gun or tool assembly comprising broadly, a single cavity air cylinder or fluid chamber, a scar type trigger mechanism 10, a chuck 12, and a limit switch 14. t
The gun proper comprises a tubular housing or body 16 open at both ends and having internal threads formed at each end. One of its ends is closed by a rear cap portion 18 and its other end is closed by a front cap 20. The rear cap portion 18 includes an air well or chamber 22 which is fully open at one end and has an air channel 24 which opens into it. The air channel 24 extends through the rear cap portion 18 from the air well 22 through its rear surface as shown in FIG. 1. The wall of the air channel 24 is threaded for part of its length. The rear cap portion 18 is externally threaded and includes an external annular groove within which an O-ring is placed to form an air tight joint with the body 16 with which it is threadingly engaged. A male plug 26 is threaded into engagement with the air channel 24 and has an axial passage formed therethrough. The lower rear portion of the rear cap portion 18 includes a cavity 28 which is closed off at its rear area by a plate 30.
A cylindrical rod or connecting means 32 has a head or piston 34 engaged at one end and a plunger 36 engaged at the other. The plunger 36 is, at its engagement with the rod 32, of less diameter than the rod 32 form- .ing an external shoulder or engaging means 38 therewith. The head 34 has an external diameter slightly smaller than the internal diameter of the body 16 and has its rear surface 40 butted against the rear cap portion 18 closing off the air well 22. An annular groove is provided on the external surface of the head 34 within which an O-ring is located forming an air tight engagement with the internal surface of the body 16. The rod 32 and its head 34 are positioned axially within the body 16. A spring stop sleeve 42 has a shank in circumscribing relation to the rod 32 and has a flange at one end which is butted against the front surface of the head 34. The front cap 20 which closes off the formed opening of thebody 16 includes air vents which open into the body chamber and a centrally located aperture through which the plunger 36 and the rod 32 extend. A compression spring 44 circumscribes the rod 32 and the shank of the spring stop sleeve 42. The compression spring 44 is trapped between the rear surface of the front cap 20 and the flange of the spring stop sleeve 42.
A tubular chuck adapter 46 is bolted to the front cap 20 extending axially and forwardly thereof circumscribing the plunger 36. The underside of the chuck adapter 46 includes a trigger passage 48 that extends from the adapter innner passage or elongate cavity to a trigger slot 50 which lies in spaced parallel relation to the axis and on the underside of the adapter 46. A tubular side port 52 opens into the inner passage of the chuck adapter 46 and is connected to a tubular feed tube adapter 54 which is engageable with a feed tube (not shown). A stop pin 56 has an arcuate terminal end and a hole 58 formed close to the other end which is fitted into the trigger passage 48.
The trigger mechanism 10 includes an arcuate handle 60 having a forward extension 62 which has a trigger pin 64 extending therefrom. The back part of the handle 60 contains a spring and finger guide 66 which is spring loaded and adapted to move within channels formed in the handle 60. A rearward arm 68 extends from the back part of the handle 60 and has an actuator member 70 extending therefrom. The trigger mechanism 10 is pinned by its handle 60 to the underside of the body 16 with the forward extension 62 lying in the trigger slot 50, and the terminal end of the trigger pin 64 engaged within the hole 58 of the stop 56. The spring and finger guide 66 is butted against the outer surface of the body 16 and the actuator member 70 of the rearward arm 66 lies in the cavity 28 of the rear cap portion 18.
18 with its plunger directed toward and engagable with the actuator member 70 of the trigger mechanism 10. The limit switch 14 is electrically attached to a tenninal socket 72 which in turn is attached to a source of electricity (not shown).
The necked down chuck 12, slotted to allow efficient engagement with a fastener, is placed at the forward end of the chuck adapter 46 as shown in FIG. 1. A chuck nut 74, which is threadingly engaged with the chuck adapter 46, circumscribes the chuck l2 and secures it in position.
The gun operates when air is passed through the male plug 26 into the air well 22 of the rear cap portion 18. The air presses against the rear surface of the head 34 moving the rod 32 and plunger 36 forward until the external shoulder 38 butts against the stop pin 56 (FIG. 2). The forward movement of the head 34 compresses the spring 44 and blocks the opening into the side portion 52 with the plunger 36. The air pressure builds up in the air well 22 and the chamber behind the head 34 urging the external shoulder 38 more strongly against the stop pin 56. Prior to the injection of air through the male plug 26, the head 34 was held in the rear position by the spring 44, with the plunger 36 in the rear position behind the port 52, and a fastener 76 was fed through the side port 52. This fastener 76 is then pushed by the terminal end of the plunger 36 further into engagement with the chuck 12 when the head 34 is moved forwardly to the position of FIG. 2 with the shoulder 38 against the stop 56. If the trigger mechanism were now to be squeezed, compressing the spring of the spring and finger guide 66, the trigger pin 64 would move withdrawing the stop pin 56 from its engagement with the shoulder 38 of the rod 32. The plunger 36 would be pushed forward driving the fastener 76 into engagement with an apertured support. At'the same time the actuator member 70 would engage the plunger of the limit switch 14.
A simple valve system (not shown) operates when the trigger is released, allowing the switch 14 to reset initiating the air cycle by first exhausting the body 16 and the air well 22 of air which allows the compression spring 44 to return the rod 32 to its original position (FIG. 1). Simultaneously with this action the valve, for an adjustable time period, allows air into the delivery system, pushing a fastener through an escapement (not shown) into the side port 52 and into the chuck assembly 12. After the time period, the valve then directs the air into the male plug 26 to move the components to the position of FIG. 2, starting the fastening cycle.
With reference to the foregoing description it is to be understood that what has been disclosed herein represents an embodiment of the invention and is to be construed as illustrative rather than restrictive in nature and that the invention is best described by the following claim;
1. Apparatus for attaching a fastener to a support, said apparatus comprising housing means forming a fluid chamber and an inner passage having one end communicating with an end portion of said chamber, a
chuck carried by said housing means at the opposite end of said passage, means behind said chuck and opening into said passage for directing a fastener into said passage and toward said chuck a plunger in said passage behind said chuck and adapted to be moved within said passage, a rod connected with said plunger and extending rearwardly into said fluid chamber, a piston connected to said rod within said fluid chamber, said housing means having means to receive fluid under pressure into said fluid chamber on the side of said piston opposite said rod, stop means having a first position extending into said passage to engage a portion of said rod intermediate said piston and said plunger to position said plunger adjacent said chuck to engage a fastener held by said chuck with said piston being in an intermediate position in said fluid chamber spaced from said one end of said inner passage and spaced from said fluid receiving means, and having a second position clear of said passage, and trigger means adapted to move said stop means from said first position to said second position to enable said plunger to move from the position adjacent said chuck substantially through said chuck to push a fastener out of the chuck and into the support.
2. Apparatus according to claim 1 characterized by resilient means carried by said housing for urging said piston toward the end of said fluid chamber opposite said inner passage, withsaid plunger then being positioned on the side of said fastener directing means opposite said chuck.
3. Apparatus according to claim 1 characterized by said portion of said rod engaged by said stop means constituting a shoulder on said rod effective to be engaged by said stop means when said rod is moving toward said chuck but not effective to be engaged by 7 said stop means when moving in the opposite direction.
4. A fastener attaching tool comprising a housing forming a fluid chamber and an inner passage having one end communicating with said chamber, a chuck carried by said housing means and communicating with the opposite end of said passage, means forming a side port communicating with said passage for directing a fastener into said passage toward said chuck, a plunger in said passage and adapted to reciprocate therein, a piston in said fluid chamber, means connecting said plunger and said piston, said housing means having means to receive fluid under pressure into said fluid chamber on the side of said piston opposite said plunger, said connecting means having engageable means, stop means having a first position extending into said passage and engageable with said engageable means to hold said plunger adjacent said chuck beyond said side port with said piston being in an intermediate position in said fluid chamber spaced from said one end of said inner passage and spaced from said fluid receiving means, and having a second position clear of said passage, and trigger means connected with said stop means and adapted to move said stop means from said first position to said second position and out of engagement with said engageable means, whereby said plunger can be moved into said chuck to push the fastener out of the chuck and into a workpiece.
5. Apparatus according to claim 4 characterized by resilient means in said fluid chamber engageable with said piston to urge said piston to a position in said chamber such that said plunger is to the side of said fastener port opposite said chuck.