U.S. patent number 3,902,238 [Application Number 05/523,188] was granted by the patent office on 1975-09-02 for impact stapling method.
This patent grant is currently assigned to AAI Corporation. Invention is credited to Franklin A. Monson.
United States Patent |
3,902,238 |
Monson |
September 2, 1975 |
Impact stapling method
Abstract
Method of impact stapling with an impact stapler having a staple
with integral pointed target-penetration and securing forward
section, rear hammer section, and medial compression shear section,
the forward section having a threaded object-securing surface
rearwardly of its pointed forward target-securing end. The staple
is propelled into a target by a percussion-ignited propellant
charge, and the forward section is secured by initial point
penetration and subsequent compression shear of the medial shear
section to enable the hammer section to impart a secondary securing
impact to the forward section.
Inventors: |
Monson; Franklin A. (Glen Arm,
MD) |
Assignee: |
AAI Corporation (Cockeysville,
MD)
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Family
ID: |
26989181 |
Appl.
No.: |
05/523,188 |
Filed: |
November 12, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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334397 |
Feb 21, 1973 |
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180333 |
Sep 14, 1971 |
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Current U.S.
Class: |
29/432; 411/440;
227/9; 227/10; 411/920 |
Current CPC
Class: |
B25C
1/18 (20130101); B25C 1/08 (20130101); Y10S
411/92 (20130101); Y10T 29/49833 (20150115) |
Current International
Class: |
B25C
1/00 (20060101); B25C 1/08 (20060101); B25C
1/18 (20060101); B23p 011/00 () |
Field of
Search: |
;29/432.1,432,432.2,526
;85/1E,1R,49,28,61 ;227/8,9,10,11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lanham; C. W.
Assistant Examiner: DiPalma; Victor A.
Attorney, Agent or Firm: Pippin, Jr.; Reginald F.
Parent Case Text
This is a division of application Ser. No. 334,397 filed Feb. 21,
1973 now abandoned, which in turn is a division of application Ser.
No. 180,333 filed Sept. 14, 1971, now abandoned.
This invention relates to a method of stapling with impact stapling
arrangements which may be utilized to effect securing of an object
to a target piece which may be formed of high-strength relatively
low-elasticity steel or the like.
Hand-held staplers have heretofore been made for attaching a metal
sheet or other object, such as a bracket, to a target in the form
of a steel plate, such conventionally incorporating a high-strength
steel stud stapled to the target and utilized as a bolt or tension
member to fasten metal sheets, brackets, or other items to the
target. A primary problem associated with this type of connection
is the fastening or retention of the stud to the target. This has
been accomplished by the partial penetration and embedment of a
knurled tapered point end on the stud staple into the target
material, utilizing a hand-held holder and propellant powder for
imparting stud penetration. Typical stud firing velocities of 750
to 800 feet per second have been utilized with hand-held stapling
arrangements. At this velocity, the stud staple may penetrate the
target sheet to a depth of 0.4 inches, which is a sufficient depth
to imbed the point and knurled surface thereon into a target sheet
of relatively low-strength, high elasticity steel, and thereby
achieve a nominally satisfactory structural joint between the stud
staple and the target sheet. In this respect, the stud is retained
in the target material of this type due to the ability of the
elastic target material to deflect in a radial direction during
stud penetration and then to elastically flow back over the stud
knurl, thereby entrapping the stud in the target sheet. The target
material entrapping the knurled point stud staple with the target
provides a stud retention which will resist tension pull-out loads
of a sometimes acceptable order of magnitude, as for instance up to
2200 pounds. However, with the prior art methods and arrangements
of this type, such have been found to be useful only in
low-strength steel target plates of up to 1 inch thickness, as
above this thickness the rebound energy of the stud is of such a
magnitude that it exceeds the transient gripping forces during
penetration and rebound, and results in the stud bouncing out of
the hole or its being loose in the target material, with relatively
low and ineffective joint strength.
This prior art stapling arrangement and method depends on the
elasticity of the steel target material in order to achieve
intimate material contact between the knurls of the staple and the
hole surface of the target material. It is also dependent on the
area of this contact in order to provide a joint of effective
structural quality. Among the disadvantages inherent in this prior
art method of stapling, in addition to those noted above, are that
the knurled stud point used for joint connection is inherently an
inefficient penetrator which must be of sufficient size and driven
to a sufficient depth in the steel target so as to insure that the
knurls of the stud are effectively engaged by the target
material.
To attempt to drive this inefficient configuration into a steel
target requires a high level of energy to achieve the necessary
stud velocity. To increase the capability of this prior art device
so as to afford greater stud holding power with a given target
material, or with respect to its use against targets of thicker
steels and/or higher strength steels, would require even higher
levels of energy, which levels of energy would produce excessive
recoil loads for hand-held operation, which is a particularly
desirable form of operation in some instances such as in underwater
use. In addition, such higher levels of energy being imparted to
the stud staple impose stringent design criteria on the stud staple
firing device and produce high structural loads on the stud staple
during penetration, which high structural loads may cause
unpredictable degradation of the stud staple. In addition, in
utilizing this prior art arrangement the steel target material must
be sufficiently elastic to properly engage the knurls of the stud
penetrating section, and this condition precludes its use for
stapling to higher strength but less elastic steels, as the
strength of the joint is relatively low in such instances, if the
joint is effective at all, as the joint strength is basically
determined by the small amount of target material which entraps the
stud knurl. Further, this prior art arrangement provides
essentially little or no capability for fastening to steel target
plates of 1 inch or thicker, even with relatively low-strength more
elastic steels.
It is an object and feature of this invention to effect a
substantial improvement in the stapling methods, and particularly
to provide a method utilizing arrangements which may be hand-held
in order to achieve higher strength joints in relatively
high-strength steels, independent of thickness, with energy
requirements compatible with hand-held operation.
It is a further feature to provide an improved staple method which
enables the utilization of a smooth pointed penetrator as the joint
connection, without the requirement for knurls or the like at the
zone of joint connection between the target and the stud staple,
and in which the stud staple may be effectively secured to target
materials of high-strength low-elasticity steels and/or steels of
infinite thickness.
Still a further feature is the provision of a stapling method which
is employed in conjunction with a staple so as to cause the staple
to impart a self-operated secondary impact for improved fastening
to a target.
A further object and feature is the provision of an improved impact
stapling or nailing method employing secondary self-impacting of a
penetrator section of a staple or nail after and as a function of
external drive-impacting of the staple or nail.
Claims
I claim:
1. The method of attaching a staple unit to a target,
comprising
imparting a forward velocity to an impact staple having a forward
point section, a hammer section and a medial compression shear
section between said point section and said hammer section, said
forward velocity being in the direction of a target mass,
impacting said staple unit at its forward point section with said
target mass,
compression shearing said medial compression shear section by
inertial mass kinetic energy action of said hammer section on the
rear of said shear section upon impact of said forward point
section with said target mass,
and forwardly impacting said forward point section by the continued
forward inertial mass kinetic energy movement of the resultant
compression-shear-separated rear hammer section of said staple.
2. The method of attaching a staple or nail unit to a target,
comprising
imparting a forward velocity to an impact staple or nail having a
forward point section and a rear inertial mass hammer section, said
forward velocity being in the direction of a target mass,
impacting said staple or nail unit at its forward point section
with said target mass,
compression shearing said staple unit intermediate said forward
point section and said rear inertial mass hammer section by
inertial mass kinetic energy action of said hammer section upon
impact of said forward point section with said target mass,
and forwardly impacting said forward point section by the continued
forward inertial mass kinetic energy movement of the resultant
compression-shear-separated rear hammer section of said staple or
nail.
Description
Still other objects, features and attendant advantages will become
apparent to one skilled in the art from a reading of the following
detailed description of a preferred mode of practice in accordance
with the invention, taken in conjunction with the following
drawings wherein:
FIG. 1 is a longitudinal section view of a stapling or nailing
arrangement employed according to the invention.
FIG. 2 is a fragmentary side view of the upper section of the
arrangement of FIG. 1, taken as viewed from the righthand side of
FIG. 1.
FIG. 3 is an enlarged view in perspective of the firing pin in the
arrangement of FIG. 1.
FIGS. 4, 5 and 6 are schematic section views illustrating
sequential steps in the method according to the invention,
utilizing the arrangement of FIG. 1 in securing the stud staple to
a target plate.
FIGS. 5a and 6a are enlarged views in partial section of the medial
shear section of the staple or nail during carrying out of the
method according to the invention, and corresponding to the shear
rupture and secondary self-impacting conditions illustrated
respectively in FIGS. 5 and 6.
Referring now in detail to the Figures in the drawings, a staple
cartridge arrangement for utilization according to the method
invention is generally indicated by the reference numeral 11, and
includes a cartridge barrel 13 having a frangible seal 15, and
within the bore 13a of which is disposed a staple or nail generally
indicated at 31, which in turn is secured as by a retaining pin 39
to a pusher generally indicated at 41. Pusher 41 is in turn
connected through a shear pin 49 to a propellant cup base 51 which
is threadedly secured in the rear end of barrel 13, and which
houses a percussion primer 53 and charge of ignitable propellant
mix 55.
The cartridge 11 is removably secured within the bore 91a of a
hand-held holder 81 which is closed at one end by closure member
85, formed of material such as steel, or other material suitable to
enable member 85 to serve as a jam washer or nut portion of a
threaded unit connection with the staple 31. Closure 85 is
press-fit into the lower open end of holder 81, and may be removed
in the course of firing and securing of the staple to a target
sheet or thereafter by simply rocking the holder 81 after target
securement. To this end, the closure 85 has a central recess 85b on
its interior face, which recess is preferably of sufficient cross
section to accommodate passage of the smooth pointed penetrator
section 31a of the staple 31 and of less diameter than the outer
thread diameter of a threaded securing section 31b rearward of the
tapered point 31a. A puncturable closure membrane 85a is formed
across the bottom of the recess 85b, and is punctured by the staple
31 in the course of firing the cartridge 11, the walls of recess
85a then engaging with threaded securing section 31b.
Securing of the cartridge 11 within the holder 81 is suitably
effected by set screws 91 which engage with the exterior of the
cartridge 11 rearwardly of a damping and center ring 16. A guard
87, with O-ring seals 89, may be secured over the area of set
screws 91, through the medium of a set screw 93, thereby affording
a substantially water-tight seal at this point between the bore 81a
of the holder 81 and the exterior of the holder, and enabling the
device to be more advantageously used underwater if so desired.
Disposed rearwardly of the cartridge 11 in the bore 81a is a firing
pin which is held in the cocked position as shown in FIG. 1,
against the action of compression spring 65, through the medium of
a retention/release pin 71. The retention/release pin 71 is held in
the retention position by a safety handle 101 which longitudinally
slidably engages therewith from the lower side, the safety handle
101 having a bifurcated end which extends between the enlarged head
of the pin 71 and the exterior body of handle 81 to prevent
movement of the pin toward the handle 81 until removal of the
handle is effected preparatory to firing. A safety pin 103 extends
through lateral holes in pin 71 and handle 81, and may be
selectively removed by exerting a pulling force thereon with a pull
ring 105, after which the safety handle may be slid downwardly
along the holder 81 for removal. In the normal safety position, the
safety handle is prevented from being angularly moved about the
axis of pin 71, through engagement of a pin 101a on the safety
handle with a guide slot 81b on the outer surface of the handle
81.
The actuator retention/release pin 71 retains the firing pin 61 in
the cocked position by engagement of retention sections 73 thereof
with enlarged release holes 61r, 61R' formed in the opposite walls
of cup-shaped firing pin 61, these retention holes being best seen
in FIG. 3, and the retaining relationship being illustrated in FIG.
1. Immediately adjacent the retention sections 73 of pin 71 are
reduced neck release sections 75, which are of sufficiently small
diameter to pass freely through release slot sections 61b, 61b'
formed in the upper end of the cup-shaped firing pin 61, to thereby
enable the firing pin to move downwardly upon the movement of the
release pin 71 to the left by a small incremental extent after
removal of the safety handle 101. The reduced neck release sections
75 are caused to be in registry with the release slots 61b, 61b' by
engagement of a shoulder stop 72 on the release pin 71 with the
exterior surface of handle 81 when the pin 71 is moved to the left,
as viewed in FIG. 1. O-ring seals 77 may be employed adjacent the
internally opposite ends of pin 71 to afford water-tight sealing of
the interior bore 81a of handle 81.
Upon registry of the reduced neck release sections 75 of pin 71
with the enlarged retention holes 61r, 61r', the firing pin will
move forward under the influence of the compression spring 65,
being guided in this respect by a set screw guide pin 94 which
slidably engages with guide slot 61a formed as a lower extension of
release slot 61b and enlarged retention hole 61r in the firing pin
61. The firing pin 61 may have one or more fluid bypass orifices 63
formed in its forward end to enable fluid pressure equalization,
and thereby enable full utilization of the firing pin force exerted
by compression spring 65.
Upon impacting of the firing pin 61 with the primer 53 the
propellant mix 55 will be ignited to effect shearing of the shear
pin 49 and movement of the pusher 41 and staple 31 downward as
viewed in FIG. 1, it being appreciated that the reference to
direction as being downward is only with respect to the Figure and
does not indicate that the device will or must be fired in any
given position. The device is capable of operating in any
orientation relative to a given target to which it is desired to
secure the staple 31 and closure nut member 85.
Pusher 41 has formed on its outer annular surface a series of
sealing and shear stop rings 41b which are separated by annular
grooves 41a, these rings and grooves serving the dual purpose of
aiding in sealing the propellant gases and also enabling final
energy absorbing stopping and retention of the pusher 41 within the
forward end of cartridge 11. To this end, there is formed at the
forward end of bore 13a in cartridge barrel 13 a shoulder stop 11a
which enables the free passage therepast of the staple 31, while
engaging the shear stop rings 41b, thereby causing the rings 41b to
be sheared as the pusher 41 attempts to move therepast, the number
of rings being sufficient to absorb the remaining energy in the
pusher 41 after staple 31 is secured to the target, and to retain
the pusher within the cartridge barrel 13 at the end of the firing
sequence.
As noted heretofore, the staple or nail 31 is formed with a
penetrator section 31a which takes the preferred form of a smooth
tapered securing point 31a, rearwardly of which is a threaded
securing section 31b which is of substantially constant thread
diameter along its length, to thereby simulate a threaded stud end
when the staple 31 is embedded in a target sheet, with the threaded
securing section 31b protruding on the exterior of the target. The
staple 31 is formed as an integral unit with a rear hammer section
31d connecting with the forward penetrator section 31a and threaded
securing section 31b through a reduced diameter shear section 31c.
A plug 42 may be employed, if desired, rearwardly of hammer section
31d to absorb shock and forward motion force between the hammer
section 31d and pusher 41.
The reduced diameter shear section 31c is formed with a sufficient
diameter to provide the necessary column strength between the
penetrator and threaded nut or washer-securing sections 31a, 31b on
the one hand and the hammer section 31d on the other hand, to
insure that the necessary precise force is imparted from the pusher
41 to the penetrator section 41a to afford desired penetration of
the point 31a into a target sheet. With a high tensile steel target
(eg 100,000 psi ultimate tensile strength), a desired and proper
extent of penetration by a point having a length of 0.45 inch and a
rear diameter of 0.230 inch, has been found to be approximately
0.35 inch. To effect this extent of penetration, using a one-piece
high-strength steel (eg, maraging steel 300) staple 31, a diameter
of approximately 0.150 inch for the frangible section has been
found satisfactory, with a 0.280-inch diameter hammer section 31d
and threaded securing section 31b thereadjacent. After the proper
depth of penetration of point 31a has been effected during initial
impact, increased resistance by the target to further point
penetration causes the frangible reduced diameter shear section 31c
to fail in compression shear, and the hammer section 31d will
continue forward to impart a further secondary impact to the rear
of the integral point and threaded securing sections 31a, 31d, as
illustrated in FIGS. 5 and 6 respectively, as well as enlarged
FIGS. 5a and 6a, the shear rupture zone being indicated
schematically at 31cs, FIGS. 5 and 5a being schematically
illustrative of the secondary impacting effected as a result
thereof, by the hammer section 31d.
As will be seen from FIGS. 4-6, the penetrator section 31a of
staple 31 passes through closure membrane 85a and the object, such
as a metal sheet 121, which is to be attached to a target plate
131, causing lateral displacement of each of the closure membrane
85a, the metal object sheet 121 and the metal target plate 131, an
effective degree of penetration being illustrated in FIGS. 5 and 6,
at which point the threaded section 31b is in radial jam engagement
with the walls of closure member recess 85b, and the smooth tapered
point section 31a is engaging with the metal sheet 121 and the
target plate 131. At this position, the resistive forces of the
target plate 131 are sufficient to overcome the column strength of
the shear section 31, thereby effecting the shear rupture as
indicated at 31cs. The remaining kinetic energy of the pusher 41
and hammer section 31d will thereupon cause the hammer 31d to
effect a secondary impact on the rear end of the penetrator and
threaded securing sections 31a, 31b, to thereby prevent the
penetrator point section 31a from bouncing out of its penetration
contact with the target 131, and also affords a further securing
action at the point of contact with the point section 31a and the
target 131. The thus embedded point is effectively secured with the
target plate, being frictionally secured and apparently to some
extent welded to the target material. It has been found that with
an arrangement of this nature the staple may be effectively secured
to withstand an axial pull of approximately 6,000 pounds, and such
has been successfully used as a fastener to mild steel, 4130 steel,
HY80 steel, and HY100 steel, in thicknesses ranging from 3/8 inch
to effectively infinite thickness.
While the invention has been described with respect to its practice
with a single preferred embodiment, it will be apparent that
various modifications and improvements will be made without
department from the scope and spirit of the invention. For
instance, while the method is described and illustrated as applied
with an illustrative apparatus in which there is disclosed a
particular means for actuating the latent energy means, it is not
necessary that such be a part of the manufactured apparatus, nor
that such be sold or furnished to a user with such an actuating
means. The actuating means could be added or supplied later at time
of use, or actuation could be accomplished manually as with a
manually wielded hammer or other impact, electrical, chemical
reaction, or other desired type of device, which might suitably
fire or otherwise actuate a primer, propellant charge, spring, or
other latent energy means. Various separate auxiliary apparatus,
both mechanical and electrical, for firing or otherwise actuating
primers, propellant charges, etc., or other latent energy means,
are well known, as in the ordnance art, and are not necessary to be
described for an understanding of this invention as to scope or
manner of alternative practice thereof by one skilled in the art.
Additionally, while the illustrative apparatus utilized in carrying
out the method employs latent energy means in the form of ignitable
propellant, it will be appreciated that other latent energy means
might suitably be employed, such as a spring, a selectively
releasable suspended weight movable under force of gravity, a
chemical composition or compositions which generate useful energy
such as gases and/or heat upon selective chemical reaction, etc.
Further, while practice of the method with the specific
illustrative apparatus has been illustrated and described, and has
been found to be a desirable mode of practice, and while various
detailed features of such apparatus may themselves be additionally
novel and inobvious, the broad invention of my double impact
nailing method with an impact-compression-shearable double impact
nail unit clearly does not require the particular structural
arrangement of the illustrative apparatus, such as the sealed
barrel 13, hand-held holder 81, cartridge 11, pusher 41,
primer-ignited propellant powder latent energy means 55, safety
firing pin arrangement 63, 73, 75, 101, 105, or energy-absorbing
shear ring arrangement 41b, 11a. For example, for normal use
outside of underwater use, a sealed barrel is not necessary, and
the initial external drive force for imparting initial penetrating
velocity to the staple or nail unit may be imparted directly to the
nail unit without use of a pusher 41, as by a spring, a weight
imparted thereagainst, or a chemical or electrical
energy-generating and force-transmitting reaction. Accordingly, the
invention is not to be limited by the illustrative embodiment, but
only by the scope of the appended claims.
* * * * *