US 3087160 A
Description (OCR text may contain errors)
April 30, 1963 T. DOPPELT STAPLING MACHINE:
Filed July 25, 19Go United States Patent Cflce 3,087,160 Patented Apr. 30, 1963 3,037,160 STAPLING MACHINE Theodore Doppelt, Chicago, Ill., assigner of one-half to Alvin Doppelt, Chicago, Ill. Filed July 25, 1960, Ser. No. 45,218 2 Claims. (Cl. 1-49) This invention relates to a stapling machine and more particularly to a powerful lightweight stapling gun of an improved construction.
Stapling machines have been widely used to drive staples into various materials in order to hold them together. The stapling machines or tackers heretofore constructed, and in particular the compressed-air powered hand carried stapling machines or guns have had certain drawbacks. First of all they are rather inefficient and when they are powered by the usual portable air cornpressor, for example such as a 1/2 H.P. compressor, they could be fired at high speed only a limited number of times, e.g. 18-35 times, before the compressor would fail to supply suicient air to maintain rapid operation. Obviously, this limits the speed of use of such a device and heretofore the deficiency could only be overcome by using larger, heavier, and more expensive air compressors that provide a larger volume of compressed air.
ln addition, when prior air powered stapling machines have been used to drive staples into relatively hard materials such as Masonite, or wood panels, the resistance of the material to staple penetration has often caused the staple being driven to fail to be driven ush, or to jam the machine. This was at least in part due to fluctuations in the pressure of the compressed air supplied by the air compressor, or due to failure of the staple driver to effect proper engagement with the staple, or due to failure of the staple driver to deliver sutlicient staple-driving force. Whenever this happens the progress of the work is slowed and the cost of labor is increased.
Another dil-liculty encountered with prior air-powered stapling machines is the -recoil and vibration produced by the recoil of the staple-driving mechanism. This recoil and vibration has frequently resulted in fatigue and loss of efliciency of the worker.
Additionally, stapling operations often require the use of staples of different size and made from different gauge wire. Prior stapling machines have had limited effectiveness in driving staples of different sizes, and it is often necessary to utilize separate stapling machines for different range of sizes of staples being used. This is objectionably expensive.
Still another problem existing with prior air-powered stapling machines lies in the fact that there is frequent mechanical failure between the head and plunger of the staple-driving means. It has been observed that such failures have been caused by a pivotal connection between these parts which occasionally permitted the piston in the stapling machine to exert force on the plunger head at an angle relative to the plunger shank. This causes sutlicient strain in the pivotal connection to eventually result in a mechanical fracture.
Another problem with prior stapling machines has been the undesirable leakage of compressed air between the air inlet passageway and the air outlet passageway when the control valve is operated. This wasted air additionally constitutes one of the reasons why the prior stapling machines could not be used at a high rate of speed when powered by a conventional portable 1/2 H.P. air compressor.
Thus, it is one object of this invention to provide a stapling machine which is more powerful than other stapling machines of comparable size and which does not jam regardless of the hardness of the material through which the staple is being driven.
A further object of this invention is to provide a stapling machine which drive-s a staple with a generally uniform driving force regardless of fluctuations in the air pressure delivered from the air compressor.
Another object of this invention is to provide a more powerful stapling machine which can fire staples practically continuously at high speed even though powered by a small 1/2 H.P. portable air' compressor.
A further object of this invention is to provide a more durable stapling machine which has a small piston recoil and low vibration.
Still a further object of this invention is to provide a more powerful air-powered stapling machine which has a small piston stroke, resulting in decreased wear between the walls of the piston and the cylinder.
Yet another object of this invention is to provide a `versatile stapling machine which is adapted to effectively drive a relatively large range of staple sizes.
And still another object of this invention is to provide a staple driving mechanism that is provided with a novel drive means which is actuated during a staple driving operation only after a predetermined driving force has first been established in the mechanism, whereby more effective operation of the stapling device is obtained.
And still a further object of this invention is to provide a staple driving mechanism that obviates the problems of -mechanical failure and jamming heretofore encountered in other staple driving machines.
Another object of this invention is to provide an improved construction for a staple gun which is characterized by simplicity of construction and by replaceability of worn parts, there-by providing for simple repair of ldamaged staple guns without discarding of undamaged parts.
Further objects and advantages of this invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this application.
A preferred embodiment of the invention is shown in the accompanying drawings in which:
FIG. l is a perspective view of the improved stapling machine.
FIG. 2 is a vertical cross-section view taken centrally of the stapling machine shown in FIG. 1.
FIG. 3 is a cross-section vie-w taken on the lines 3-3 of FIG. i2.
FIG. 4 is a cross-section view taken on the line 4-4 of FIG. 2.
FIG. 5 is a perspective view of the staple pusher.
FIG. 6 is a reduced perspective View of the extended end of the staple magazine.
FIG. 7 is `an exploded fragmentary perspective View of the head of the plunger.
Referring now to the drawings, there is shown in FIG. l, a perspective view of the stapling machine generally indicated at 10., and comprising a housing indicated at 12 that includes a body portion 14, an integrally attached transversely extending handle 16, and an integrally attached and transversely extending part 18 that is spaced from handle 16.
The body 14 of the housing 12 is provided internally with a cylindrical bore 20. The wall of bore 20 adjacent the upper end thereof is threaded at 22. A removable cap 24 carrying a sealing lO-ring Z5- cooperates with threads 22 to close off the upper end of the cylinder and to provide an air-tight seal. At the lower end of the cylindrical bore 20 there is provided an annular abutment shoulder, or base, 26 having a counterbore 28 centrally thereof which communicates with an elongated, diametrically disposed slot, or recess, 30 that opens outwardly of body 14. Since the slot is, in its narrow di- `taining' ring 62.
`at 34, which is sub-assembled Aas a `unitl for Connection to thebody 14. The "sub-assembly 34 includes a nose or plunger-and-staple guideway'rneans 36 that is positioned 4in slot 30. The'plunger-and-staple guideway means 36 itself is a replaceable'unit that is formed from two ilat plate member 38 and 40 that are detachably held together by a lirst pair of screws 41'and a second pair of screws 42. 'I'he second pair of screwsl also connect to the body 14 on'oppos'ite sides of slot 30, and thereby serve as part of the means yfor securing sub-assembly 34 to body 14.
The plate Y40is providedv with a centrally positioned straight groove 44 which is channel shaped in cross section. An intermediate portion of the base of the groove 44 is cut away'to'form 2an opening 4S through which staples may be fed into groove 44. Plate 38 is provided with `a straight slot 46 of leasen width than groove 44 extending from the lower edge of plate 38 but terminating short of the top edge. The plate members 38 and 40 are removably held together to define plunger and staple there is required onlythe replacement of the worn plate so that theA unworn, parts can still be used. In addition, as V'seen inl FIG. 1, the lower parts of the plate members are lredueecl Ain width to form a comparatively narrow chin 36a which helps position the stapling machine on the work. Y
Aplunger bla-de 50 is provided. 'Ihe plunger blade v-is economically stamped lfrom flat sheet metal and comprises a shank portion 52 and an enlarged integral head portion 54 with straightupper edgeV 55.` The shank portion'SZ `of plunger 150 is slidably mounted in the plunger and staple guidew'ay48and is positioned above and in registry with any staple therein, as seen in FVIG. 2..
The head portion 54vhas cylindrical blade holding means releasably secured thereto in the formof a pair of semicylindrical blade holding parts )516'and 5 8, having radially enlarged groovedftlanges A57 and '59 'that together-'denne a peripheral groove 60- for receiving therein a split re- The head v54'of "the 'plunger` blade is provided withnotches 54d on opposite edges for register with'g'r'oovef60. The 1"in'g""`62` thus operates "to secure the partera` '6 and '58 tothe 'plung'erfhd y54. The size fsurfac'e v70 isv l"generally planar, v'although this is not a necessary'condition.V The tit between vthe sides of the piston and the cylinder is close enough to generally prevent the passage of air therebetween, 4but should `prolonged l' use 4of the `stapling machine 'resultfin wear which impairs the propert, afspring biasedcompression ring (not shown) may be'inserted in the peripheral groove 72,
'that is provided piston '68, to restore the proper tit.
The underside ofup'istciiiitSy Vis provided with a vcentral recess' 74 the bottom wall 76 of which is convex to provide `substantially one point direct contact between the vcenter of the top edge .'55 of the head :54 and the center or apex of the convex wall 76. It willbe understood 'that "the *blade holding `partst56 and 58 cooperate with the "cylindrical walls of recess' 74 lto' properly position vthe plunger blade so that edge5'5 of'headf54 engages the apex of the convex wall 76, as shown in FIG. 2. This arrangement is important because it obviates the use of a pivotal connection betweenV the plunger `shank and the plunger head which heretofore has been the frequent cause of mechanical failures in other stapling machines.
A coil spring is mounted in bore 20 with one end pressing against the underside of flanges 57 and 59 and the other end entering bore 28 and seating against a portion of body 14 so as to norm-ally bias piston 68 to its retracted position shown in FIG. 2. This arrangement eiectively couples plunger blade 50 with piston 68 so movement of the piston 68 in bore 20 causes a corresponding movement of the shank 52 of the plunger blade 50 in 'the staple and plunger guideway 48. When piston 68 moves downwardly, the spring is compressed. Then when the force urging the piston down is removed, the energy stored in the compressed spring helps return the Ipiston to its retracted position. The spring 80 is a light one and provides just enough force to restore the piston 68 to a position adjacent the closed end of bore 20. A washer 82, formed -from rubber or some similar resilient material, is seated on the shoulder 26 and acts as a bu'mper to absorb the impact of the moving piston 68 at the bottom'of its stroke.
The cap 24 has a boss 86 thereon which extends concentrically into the bore 20 in spaced relation to the walls of bore l20 to denne an annular space, or gas chamber, -88 between boss 86 and the walls of bore Z8'. Magnetic means are provided between the boss 86 and piston 68', the one being a magnet and the other of magnetizable material. In the preferred embodiment a magnet 87 is provided in boss 86, and the piston 68 is formed from a magnetizable material. When the piston is in its retracted position with its top surface 70 engaging the adjacent surface of magnet 87, the piston is held in that posi- `tion by magnetic attraction.
A conduit 90 is provided in handle 16 which opens into the side of gas chamber 88 above piston 68 when it is in retracted position, as shown in FIG. 2. When air under pressure enters chamber 88 from conduit 90 it exerts a force on the piston y68 that tends to move the piston along bore 20. Actually, however, there is no movement of piston 68 untilafter the air pressure in chamber 88 rises to a level where it exerts a force on the piston suiiicient to break the magnetic attraction between the magnet 87 and the piston 68. When this happens, the
`piston 68 moves downwardly in bore 2t) with what could be termed explosive `force. Since piston 68 is coupled with plunger 50, this movement of piston 68 produces a corresponding movement of the plunger. This is important because any staple in guideway `48 will then be driven toward the staple ejecting end 49 by the almost explosive force so it can penetrate harder materials than has been heretofore possible.
Additionally, the driving force of the piston 68 and the plunger 50 is so great that even when the staples are driven against an impenetrable material such as steel, the legs of the staples may crumble, but the staple will not jam in the guideway 48. It is also noted that since a pre-determined Vforce must exist in chamber 88 before piston 68 moves, the driving force on the staple is generally uniform and is independent of iluctuations in the air pressure output 'of the air compressor because if the output of the air compressor is so low that the pressure in chamber 88 does not reach the proper level the stapling machine simply wont operate. In contrast, when staples driven by prior stapling machines were directed against such hard materials as ceiling tile or wall paneling, sometimes the staples would penetrate the material, and sometimes .they wouldnt, depending on the magnitude of the air pressure from the air compressor.
It is apparent that other modications of this disclosed embodiment are possible. For example, the magnet could be secured to the top surface 7G of piston 68 and the base portion of cap 24 could be formed from magnetizable material. Alternatively magnets could be inserted in the inner walls of the cylinder to grip the 'side surfaces of the piston. In addition, a magnet could be attached both to the top surface 70 of the piston 68 rand Ithe bottom surface of the cap 24 to further increase the magnetic force holding the piston in its retracted position. It is also apparent that many other structural variations are available for delaying the movement of the piston until the pressure builds up to a desired value.
However there is a particular advantage in using magnetic means for holding the piston in its retracted position where the direction of magnetic attraction is axial, because with this arrangement, the coil spring 80 only has to be strong enough to lift the piston 68 to the vicinity of the magnet and the magnetic force will lift the piston the rest of the way. This means that the spring 80 may be weaker and consequently less energy will be used and lost in compressing it. This results in lower energy requirements from the air compressor which powers the stapling machine.
In particular, it has been found that with a magnetic retaining force of v9 lbs., and with chamber 88 having a volume of about 1/10 of the total expanded gas chamber volume when piston 68 is in its forward position, the stapling machine may be fired as rapidly as possible for an almost indefinite period without exhausting the air supply from a small 1/2 HP. air compressor, which is a size typically used in a portable operation. Furthermore, it has been observed that such a machine has very little recoil force and vibration so that the stapling machine can be used for long periods without causing fatigue.
As best seen in FIG. 2, the handle 16 on body 14 is provided with a high pressure air inlet pasageway 92 and a parallel air outlet passageway 9'4. A conventional snap coupling hose connector 96 is screwed into the threaded end of inlet 92 and is adapted to be connected to the those from an air compressor. The opposite end of the inlet 92 is arranged to communicate with conduit 90 through a valve means indicated generally at 100.
As seen in FIG. 2, the valve means 100 includes an elongated bore 102 spaced portions of which communicate with inlet 92 and ou-tlet 94 and with conduit 90. The bore 102 includes an enlarged portion 184, a reduced intermediate portion 106, and a further reduced dimension portion 108.
The walls of the enlarged portion 104 are threaded to accommodate a closure cap 110 carrying a sealing O-ring 112 to prevent leakage of high pressure air through cap 110. A recess 114 is provided in cap 11) and receives one end of a coil spring 116 therein.
A valve 118 with an integrally attached valve stem 120 is provided with valve 118 positioned in enlarged bore portion 104. Valve 118 provides a resilient sealing portion 122 clamped between discs 123 and 124 and adapted to seat on valve seat 126 located between inlet 92 and conduit 90. The spring 116 normally biases the valve 118 to a closed position. A hard rubber sleeve 128 is telescopically mounted on the valve stem 120 and slidably in the reduced bore portion 108. Telescoping of sleeve 128 on stern 120 is limited by engagement of the tip of stern 120 with the closed end of sleeve 128. This sliding engagement is tight enough to prevent the passage of high pressure air between the sides of sleeve 128 and the walls vof bore portion 108.
The lower end 129 of sleeve 128 extends outwardly of bore 102, as shown in FIG. 2. An actuating trigger lever 130 pivotally mounted on handle 16 is positioned to engage the lower end 129 of sleeve 128. With this arrangement when the handle or side portion is gripped so lever 130 is actuated, sleeve 128 is forced up along bore 102 in the handle 16 to operate the valve means 100 as described below.
Before lever 130 is actuated, the sleeve 128 protrudes from bore 102 so as to expose outlet 94 to communication with the unoccupied portion of bore 102 which in turn communicates with conduit 90. As the lever 130 is forced against the end 129 of sleeve 128, the sleeve first telescopes onto stem and slides in bore 102 to a position which closes olf outlet 94. Then sleeve 128 engages the tip of stern 120 and further movement unseats valve 118 from valve seat 126 thereby communicating inlet 92 with bore 102 and conduit 90. When trigger 130 is released, the spring 116 and air pressure first restores valve 118 to seating engagement with valve seat 126. Then the pressure of the air in conduit 90 exerts force on sleeve 128 to cause same to slide outwardly to expose the outlet 94.
The foregoing operation is useful because after a piston stroke, the piston 68 moves back to its initial position and its return movement is softened by a cushion of momentarily trapped air in gas chamber 88 and conduit 90. However, as the air pressure rises in the gas chamber 88 and conduit 90, sleeve 132 is forced back to its initial position permitting air to escape fast enough so that the piston 68 can rapidly return to its retracted position. The net effect of this arrangement is to soften piston recoil without wasting air.
The part 18 of body 14 is part of the staple feeding means and cooperates with the magazine portion of subassembly 34. The magazine portion of sub-assembly 34 is indicated at 132 and is spaced from part 18 by a longitudinal slot 134. The extended ends of part 18 and magazine 132 are secured in spaced relation by a closure plate 136 that is connected to the two parts by screws 138. The part 18 is longitudinally recessed at 140 and carries a transverse anchor pin 142 to which is anchored one end of elongated feed spring 144, and a second pin or roller 146 over which the spring 144 is trained with the other end of spring 144 connected to the lug 150 of a staple feeder 148. Shim means 152 in the form of one or more shim plates are secured to the lower side of part 18 by screws 153. The shim means 152 is longitudinally slotted at 154 to provide for entrance of lug 150 into recess 140. The extended end of part 18 and shim means 1152 are shaped to define a triangular recess 156, as seen in side elevation, that provides an inclined edge 158.
As best seen in FIG. 3, the magazine 132 is U-shaped in cross section with a base and spaced parallel legs 162. A staple track or magazine rail 164 is removably but rigidly mounted in groove v164a by means of screws 164b in the magazine 132 intermediate legs 162 and parallel thereto, and in this embodiment the upper edge 165 of magazine rail 164 extends a little above the upper edge of legs 162. One end 166 of rail 164 extends into slot 45 in plate 40 and terminates coplanar with the base of groove 44 as seen in FIG. 2. The rail 164 is dimensioned relative to slot 45 to permit passage of a single staple therebetween into guideway 48. The other end 167 of rail 164 is tapered and protrudes rearwardly through an aperture in plate 136 to serve as a guide for inserting a stick of staples into the magazine 132.
As earlier pointed out, the sub-assembly 34 of the jaw and magazine is removably mounted on body 14. Since the size of the guideway 48 in jaw portion 36 and thesize of magazine rail 164 controls the size of staples which the stapling machine can drive, it is apparent that by simply replacing the removably mounted sub-assembly 34 the size and shape of the staples that may be driven by the machine may be changed.
The staple feeder 148 is adapted to move along 4slot 134 during the staple feeding operation. The feeder has a planar base 170 that slides in slot 134, a pair of upstanding grippable ears 172 located outwardly of part 18 and cooperating with part 18 to guide the feeder, and a pair of spaced depending legs 174 which straddle rail 164 and the lower edge of which slopes upwardly and rear- Wardly to planar base 170. This sloping arrangement of legs 174 permits of positioning the feeder 148 in triangular recess 156 spaced above the upper edge 165 of rail 164 to permit insertion of a stick of staples into magazine 132.
The size of slot 134, between edge 165 and part 18 may be varied to accommodate staples of various thicknesses merely by varying the thickness of removable shim means 152. By selecting the size of shim means 152 to the thickness of the staple stick, one may insure that staples will not climb up on one another in the magazine and thereby jamming in the magazine may be avoided.
To operate therstaple gun, the staple pusher 148 is iirst retracted and pivoted to thedotted line position shown in FIG. 2. Then a stick of staples is inserted on magazine rail 164 in the magazine 132 and the staple pusher is pivoted back into slot 134 and permitted to engage the rear ofl the staple stick. This forces the staple stick forward until the iirst staple in the stick moves into the staple and plunger guideway 48. Next a high pressure hose from an air compressor is attached to connector 916. Then to drive a staple it is only necessary to hold the handle so the staple ejecting end 49 is properly positioned against the work and then the lever i130 is actuated as described above. This operates valve'110 and after the air pressure in the ygas chamber 8S rises above a predetermined level the piston drives the single staple that is located in guideway .48 into the Work.
While there has been shown and described a particular embodiment'of this invention, it will be obvious to those fskilled in the art that various changes and modifications `may be made therein without departing from the invention and, therefore, it is intended in the `appended claims to co'verall such changes and modifications as yfall within the true spirit and scope of the invention.
What I claim as new and desire to secure by Letters Patentof the United States is:
1. In a stapling machine ofthe type comprising a housing, elongated Aplunger and staple guideway meansin said-housing, said guideway means having an open staple ejecting end, a plunger slidable in said guidewaymeans and positioned in registry with a staple therein whereby movement of said plunger in one direction thrusts said f8 staple insaidguideway means. toward said staple ejecting end to eect driving'of Vsaidgstaple, means for moving said plunger in said one direction to drive a staple, said housing having an elongated feed portion extending transverse to said guidewaymeansrsaid feed portion comprising an elongated magazine rail fixed in said feed portion to slidably accommodate a stick of staples,` said feed portion having a replaceable retainer spaced from said magazine rail and positioned ,close enough thereto to prevent staples lfrom leaving the magazine rail ina direction generally transverse thereto, feeding means for biasing a stick of staples on said magazine rail toward one end thereof whereby the end staple in said stick is forced into said guideway means preparatory to being driven, and means for regulating the spacing between the said retainer andthe magazine rail in accordancewith the gauge of the wire composing the stick of staples, to prevent the feeding force on the staple stick exerted by the biasing means from causing staples in the staple stick to break off and climb on each other to jam the stapling machine.
2. A stapling machine as set forth in claim 1 wherein the means for regulating the spacing between the said retainer and the magazine rail comprises at least one shim plate removably mounted on the housing and spaced from the magazine rail.
References Cited in the file of this patent UNITED STATES PATENTS 406,075 White July y2, 1889 2,585,939 .Tuilfs 'Feb. 19, v1,952 V2,585,942 Juilfs Feb. 19, 1952 2,698,938 Stebbings Jan. 11, 1955 v 2,707,277 Aldrich May 3, 1955 2,713,165 Campbell July 19, 1955 2,786,450 Jacobus Mar. 26, 1957 2,801,418 Jenny Aug. 6, 1957 2,947,003 Ericsson Aug. 2, 1960 2,983,922 Juil-fs ;May 16, 1961