Note: Descriptions are shown in the official language in which they were submitted.
TEC~NICAL FIELD OF THE INV~NTION
The present invention relates to a gripping impact
wrench socket and in particular to a socket assembly
driven by an impact wrench with automatic inwardly
clamping jaws for gripping studs, threaded collars,
couplers, and other cylindrical fasteners and the like
for non-destructive removal andior tightening thereof.
BACKGROUND OF THE INVENTION
Previously known impact wrench sockets, of the type
for automatically gripping coupling collars, have been
substantially complex in construction and subject to
breakage and malfunctions. One such complex gripping
socket was disclosed in U.S. Patent No. 4,932,292 which
required eight internal moving parts including three cam
driven jaws, each jaw having an ear or guide pin ~ormed
on one surface thereof for circumferential spacing and
radial motion guidance through an interface with radial ;
channels formed in a guide bushing. The jaws were biased :.
in an outward direction so that an exterior cam face of
the jaw inter~aced with an interior cam face of the
housing. The outward bias was pro~ided by coiled
compression springs positioned inside the bushing member
guide channel, so that each spring pressed outwardly
against a separate tab or guide pin formed on each
gripping jaw. The spacing between the jaws
circumferentially around the wrench was maintained by the
spacing of the guide channels in the bushing member such
that the guide tabs or pins were subject both to radial
tension from the spring and also to rotary impact loading
due to inevitable uneven distribution of twisting forces
among the jaws. Further, the entire internal working
mechanism was held in place using a cover plate which was '
attached using threaded fasteners.
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While it was theorized by others that the number of
jaws could be reduced to two from the three previously
known, the resulting reduction of the internal parts from
eight to six only resulted in a partial savings of
manu~acturing costs. Yurther, the reduction o~ the
number of shoes was found to result in further uneven
distribution of twisting forces and thereby exacerbated
the problem of guidance tab breakage. Thus, completely
successful use of two jaws prior to applicants' inventive
impact gripping socket wrench construction was not
successfully accomplished. Moreover, the advantageous
construction of applicants' invention can also be
applicable to a plurality of gripping jaws with many of
the same advantages over the prior known gripping impact
wrench sockets, including reduced jaw breakage, reduced
manufacturing cost, and increased reliability and
durability.
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SUMMARY OF THE INVENTION
Various drawbacks of the prior known gripping socket
wrenches have been overcome by the present invention in which
the number o~ internal moving parts has been reduced by using a
unitary cage, a single ring spring and a plurality of shoes.
Preferably only two shoes are usea. The tubular wrench housing
has been constructed for maximum strength at the cam housing and
at the anvil. The weight of an extension tube portion which
allows elongated threaded studs to be traversed by the gripping
jaws for maximum effectiveness has been minimized. The cage and
gripping shoe assembly is held in place at the distal end of the
cam housing for ease of assembly and disassembly while maintain-
ing axial pulling strength.
More specifically, the invention provides improved
simplified construction gripping socket wrench for use with an
impact tool driver, the socket wrench of the type having a
generally cylindrical one piece housing, a driving socket at a
proximal end of the housing, internal cam sur~aces symmetrically
positioned about an interior of the housing adjacent a distal
end of the housing, and symmetrically positioned clamping jaws
held within the housing at the distal end, each having an
interior gripping face actuated inwardly by relative partial
rotation between the symmetrically positioned clamping jaws and
the internal cam surfaces, the improved construction comprising: -
(a) a unitary cage for holding the clamping jaws symmetrically
positioned for opposed radially inward actuation by the internal
cam surfaces, th~e unitary cage having a cylindrical body with
solid sector openings formed therein for slidably holding the
74883-1
clamping jaws, and spaced apart cylindrical sector interior
surfaces interposed between the sector openings, each interior
sector sur~ace having a spring groove formed to a predetermined
depth thereinto, centrally located and circum~erentially aligned
with each other spring yroove in each other interior sector
surface of the cage; ~b) an arc shaped groove formed centrally
located in the gripping face of each of the clamping jaws which
arc snaped groove is undercut a predetermined depth corresponding
in location and depth to the central location and the
predetermined depth of the spring ~roo~e formed in ~he cylindrical
sector interior surfaces of the unitary cage: and ~c) a ring
spring having a thiekness less than the predetermined depth of
~he spring groove and the arc shapea grooves in the interior
cage sur~ace and the gripping faces o~ the clamping jaws and
having a diameter sufficient to put tension on the jaws
outwardly against the symmetrically positioned cam surfaees.
The invention also provides a gripping impaet. soeket
wrench of the t~pe with a hammer-receiving anvil for use with an
impact wrench driving tool of the type having a driving hammer
thereon, the impact socket wrench comprising: (a) a housing
symmetrically formed about an axis, with a socket defining an
anvil for receiving the hammer of the impact wrench driving tool
at a proximal end of the housing, and a cup portion having an
interior opening and an interior wall formed at a distal end of
the housing including a plurality of symmetrically positioned
internal cam surfaces formed circumferentially around the
interior wall of the cup portion; (b) a plurality of jaws
slidably positioned within the cup portion, each jaw formed
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74883-1
generally in the shape of a solid sector o~ a cylinder having two
substantially flat parallel end eXterior SUr~aCeS and two
substantially flat an~led side exterior surfaces, an outer cam
surface mating with one of the internal cam surfaces at the
interior of the cup portion of the housing, and an inner gripping
~ace evenly scored for defining a generally cylindrical arc
sur~ace, 'hereby defining a shape of the ~aw which is generally a
solid sector of a cylinder; (c) a unitar~ generally
cylindrically shaped cage member held in the housing cup portion
for partial rotation about a central axis of the housing and for
maintaining the jaws in symmetrically opposed positions circum- -
ferentially around the interior opening of the cup, which unitary
cage holds the jaws through substantially flat surface-to-surface
sliding engagement with the side and end exterior flat surfaces
of the jaws; and ~d) a centrally acting ring spring acting with
generally uniform tension on each of the jaws to bias the jaws ~ -
outwardly against the internal cam surfaces on the interior walls
of the cup portion. `
A further preferred feature of the gripping impact
socket wrench is the addition of a retaining pin to the combina-
tion socket wrench disclosed, which pin extends diametricall~
through the anvil receiving end. The pin is inserted through a
corresponding orifice in the anvil and through the hammer of the
impact driver to hold the socket wrench in place on the impact
driver. The pin is retained using a resilient ring member
positioned in a groove correspondingly covering both ends ~f the
orifice formed for the pin. This socket retention mechanism in
74883-1
cooperation with the gripping mechanism which maintains its grip
through frictional cam tension on the rod or coupler being
removed allows the entire assembly to be safel~ withdrawn without
releasing the coupler before desired by the operator. The cage
is constructed with a flat angled stop surface which upon
driving the wrench in reverse pushes the gripping shoes outwardly
thereby releasing the frictional grasp on the stud or coupler
being removed.
BRIEF DESCRIPTION OF TH~ DRAWINGS
These and other a~vantages and objects of the present
invention will be more fully understood with reference to the
detailed description below and the drawings in which like
numerals represent like elements and in which:
Figure 1 is an exploded perspective view of the
inventive impact socket wrench assembly; `
Figure 2 is a schematic cross-sectional view showing
the operation oE the gripping impact wrench in a non-gripping
position; and `
Figure 3 is a schematic cross-sectional view of the
inventive wrench showing the operation of the various features
of the wrench while in its gripping position.
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DETAILED DESCRIPTION OF T~IE PREFERRED EMBODIMENTS
Figure 1 shows an exploded perspective view of the
inventive socket assembly 10 which comprises a
cylindrical housing 12 having an anvil 14 at its proximal
end. In this disclosure a terminology convention will be
adopted in which the direction toward the impact driving
tool will be termed "proximal" and the direction away
from the impact driving tool will be termed "distal".
Extending from the anvil 14 there is an extension member
16 which is preferably genèrally cylindrical for
convenience of operation and holding of the tool. A
connector pin 18 is advantageously inserted diametrically
through a pin hole 20 to engage the hammer of the driving
tool to avoid axial detachment of the wrench from the
driving tool. The connector pin 18 is advantageously
retained with a resilient retaining ring 22 which
expandably slides over the exterior of anvil 14 and down
into a circular groove adjacent both ends of the pin hole
20. The anvil 14 will be formed in the proxlmal end 25
of the wrench and, at the distal end 28, a cup housing
portion 30 will be formed having a distal lip 32 thereby
defining the opening of a hollow cavity therein.
Adjacent at the proximal end o~ cup 30 is a proximal
slide surface 34 which may be generally disc shaped for ;~
sliding support of a unitary cage 54 as will be described ~`
more fully below. Adjacent to the slide surface 34, a `
cage support rim 36 is advantageously formed which is
generally cylindrical in the preferred embodiment and
which corresponds in diameter to the proximal end of cage
54. Adjacent lip 32 is a distal cage cylindrical support ~
surface 38 which is sized for sliding engagement with the ;
distal end of unitary cage 54 as will be described more
fully below.
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Within cup portion 30, there is a first internal
cam surface 40 and a second internal cam surface 42. The
internal cam sur~aces are pre~erably integrally ~ormed
within cup portion 30 of the cylindrical housing 12.
While two internal cam surfaces are shown diametrically
opposed in the preferred embodiment of figure 1, some of
the advantages of the inventive wrench construction
according to the present invention can also be obtained
with a plurality of cam surfaces formed symmetrically
tO about the tool axis 11 and evenly spaced
circumferentially around the interior of cup 30.
Each o~ the cam surfaces forms the same cross- .
sectional shape with a progressively decreaslng radius
from a first cam maximum radius 46 to a first cam minimum
radium 48. Similarly, the second cam radius decreases
progressively from the maximum second cam radius 50 to
the minimum second cam radius 52. In the preferred
embodiment shown, in which two internal cam surfaces are
provided, the maximum first cam radius 46 is ..
~0 substantially immediately adjacent the second cam minimum
radius 52.
A unitary cage 54 is provided in the assembly. :
Unitary cage 54 preferably has a distal cage end 56 which
in the preferred embodiment comprises a cylindrical rim
formed generally disc shaped adjacent end 56, with a
cylindrically shaped first bearing surface 58 formed
around the periphery thereof. The bearing surface 58 is
sized for partial rotary sliding engagement with internal
cylindrical cage support surface 38 of cup 30.
The proximal cage end 60 preferably includes a
second cylindrical bearing surface 62 which is formed
around the periphery of a disc-shaped proximal end
surface 61. Upon assembly the cage 54 is inserted into
the cup 30 such that the disc-shaped proximal end 61 is
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in sliding engagement with disc--shaped slide surface 34
of the cup housing 30 and each of the cylindrical bearing
surfaces 58 and 62 will be in s;Liding angagement with
corresponding cage support surfaces 36 and 38
respectively.
In the preferred embodiment both the cylindrical
housing 12 and the cage 54 will be constructed of durable
surface hardened steel so that sliding engagement between
the two surfaces is achieved with minimum wear.
While the interior material provides durable non-
brittle strengthr the unitary cage 54 has a plurality of
openings including a ~irst opening 64 and a second
opening 66 with each opening in the shape of a solid -~
sector of a cyllnder for holding gripping j aws 74 and 76
15 in the preferred embodlment as shown . It being
understood that additional solid cylindrical shaped
sector openings may be constructed for corresponding
additional cam surfaces and gripping jaws. However, it
has been found that the present inventive construction
advantageously permits a two jaw construction. The two
jaw construction allows the jaws 74 and 76 to be
diametrically opposed thereby maximizing gripping power.
Further, it has been found that a unitary cage provides a
maximum cage strength when constructed for two jaws which
thereby reduces cracking and breakage of the cage
assembly during the impact operation. The cage 54
advantageously supports the jaws 74 and 76 for axial and
radial alignment during operation. The cylindrical cage
body 68 is of a diameter less than the minimum diameter
of the cam suxfaces so that the gripping jaws are held
within open sectors 64 and 66 and extend therethrough.
Thus the gripping jaws 74 and 76 can be actuated through
a full range of radial movement corresponding to the cam
slope. A further advantage of a two jaw construction is
that a more shallow cam slope produces great clamping
force. Thus the twisting power of the impact wrench is
multiplied through the shallow slope cam surfaces to
provide maximum gripping. For a given cam slope the
amount of radial movement is increased with the
circumference covered by the cam such that two cams
provide more radial travel than three.
The cage includes a hollow cage opening 70 through
- which a work piece, such as a stud, a rod, or a coupler
can be inserted. The hollow cage opening 70 is
preferably sized to correspond to a hollow opening 72 in
the extension tubing 16. This allows threaded studs and
similar work pieces having external threads to be
inserted into the extension so that the gripping jaws can
clamp onto a solid exterior surface of a rod and avoid
any potential thread damage. Also it has been found that
for studs threaded into a surface, it is preferable to
grip the studs immediately adjacent the surface to reduce
the chance of stud twisting or fracture and to maintain
axial stability while the tool is being operated.
The cage movably holds a first gripping shoe 74 and
a second gripping shoe 76, each shoe generally having a
cylindrical gripping surface which is formed with a
scored matrix for non-slipping grip of the work piece,
stud or coupler. Each shoe 74 and 76 also has an
external cam surface correspondingly shaped to interface
along the entire internal cam surface of the cup 30. For
convenience and clarity the structure of each gripping
shoe will be described in connection with a single
gripping shoe it being understood that the same structure
is intended for each of a plurality of shoes. Each
external cam surface 80 has a leading edge 82 and a
trailing edge 84. The radial shoe thickness decreases
progressively from the leading edge 82 to the trailing
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edge 84. There is a generally flat angled push surface
86 which when assembled forms a radial plane
substantially aligned with the axis o~ the tool. There
is a corresponding cage pushing surface 88, which
operates against gripping shoe surface 86 as will be more
fully explained with reference to figures 2 and 3 below.
Each open pie-sector of the cage also has a radial
proximal radial slide surface 90 and a distal radial
slide surface 92 which are spaced apart in the cage
corresponding to the distance between a proximal shoe end
94 and a distal shoe end 96. The two shoe ends 94 and 96
and the two cage radial slide surfaces 90 and 92 define
sectors of a plane perpendicular to the axis of the tool.
The cylindrical gripping surface 78 projects adjacent to
the internal cage opening 98 for access to the stud or
coupler rod to be gripped. An outwardly biased ring
spring lO0 is provided to push outwardly to hold the
shoes radially outwardly such that the cylindrical
gripping surface is projecting only slightly into the
hollow cylindrical opening 70 of the cage 54. In this
manner any stud, rod, coupler or the like which can be -
inserted through the opening of the cage will also push
past the gripping jaws in the outwardly biased non-
torquing position. It has been found advantageous to use
a single ring spring lO0 pushing centrally against both
of the shoes simultaneously. Thus a central shoe spring
groove is formed in each cylindrical gripping surface
which groove is in the shape of an arc parallel to the
proximal and distal shoe ends and substantially halfway
therebetween. Thus the outward tension of the spring
acts evenly against the entire shoe and does not tend to
tilt it or twist it as springs on one side or the other
of the shoe~ would tend to do. Also, the single spring
has advantages over having springs at both ends of each
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shoe as the tension in one spring may be different or may
be lost during operation such that uneven radially
outward pressure is placed on the shoes thereby causing
them to tilt. Tilting gripping shoes may lead to
malfunctions and breakage during operation. The cage
construction includes a cage spring groove 104 such that
the spring loo is below the sur~ace exterior to the
hollow cage opening 7 0 and does not inter~ere with
insertion of a work piece.
Thus during clamping operation the cage pushing
surface 88 acts upon the entire push surface 86 of the
gripping shoes evenly forcing the entire shoe cam surface
80 to slide along the interior cam surface 40 or 42 o~
the housing. The sloped progressive decrease in diameter
o~ the cam surfaces force the jaws inwardly thereby
clamping against the work piece. The construction is
symmetrical such that the jaws 74 and 76 will clamp
substantially evenly with even force against the work
piece. The cage 54 has a stop surface 106 which acts
together with pushing surface 88 to prevent the shoe from
extending inwardly too far. This prevents the gripping
jaw cam surface from moving beyond the trailing edge 48
or 52 of the cup housing cam surfaces in a manner which
might cause denting or excessive wear in the cam surface
thereby maintaining the durability and smooth operation -
of the tool for multiple uses. As indicated previously,
the range of sizes is maximized through the unique
ability of the unitary cage construction to permit two
shoe impact wrench to be constructed. However, when the
maximum size range is exceeded alternate size wrenches
can be constrllcted.
The cage 5~ is advantageously held axially within
cup 30 with a circular clip 108 inserted or "snapped"
into an annular groove 110. This assembly replaces
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previously known cover plates thereby reducing
construction cost, reducing material weight and avoiding
bulky and aw~ward end construction.
With reference to figures 2 and 3, the operation of
the inventive wrench can be better understood in which
figure 2 is a schematic section view showing the impact
socket wrench in a non gripping position. It can be seen
that spring 100 holds the shoes outwardly against the
maximum radius of the external cam surfaces, preferably
this maximum radially outward extension corresponds to
the cylindrical gripping surfaces forming an opening
equivalent to the hollow cage opening 70.
With reference to figure 3 which is a schematic
section view showing the shoes and cup moved into a
gripping position it can be seen that partial rotation of
the tool as indicated by arrow 112 moves pushing surface
88 of the cage 54 against the pushed surface 86 of the
shoes. This rotates the shoes in a direction 114
relatively opposite from the direction of rotation of the
wrench 108. The radially inward motion of the gripping
jaws, schematically depicted as arrow 114, provides
substantial clamping force due to the multiplied force
ramping effect of the shallow cam slope or angle. `~
The shallow angle and the scored gripping ;
cylindrical sur~ace of the shoes act together with
standard compressibility, yielding, and elasticity of the
metal material of studs and couplers to thereby maintain
the shoes clamped inwardly against the work piece even ;
after the torquing of the impact driver tool in the
direction of arrow 112 is released. This allows the
wrench to be pulled back thereby maintaining a grip on
the work piece so that it does not inadvertently drop out
of the end of the wrench. The wrench as described
previously is held in place with a retaining pin 182 and
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the cage and jaws are held in place with clip 108 so that
the entire assembly can be used in any position without
fear of dropping the work piece or the wrench into hard
to reach places or into areas where damage may occur.
Release o~ the tool against the work piece is easily
accomplished through counter rotating the tool such that
the stop surface 106 of the cage pushes against the
trailing ~dge 84 of the shoe thereby moving the cam
surfaces into a non clamping position. The tension from
ring spring lO0 quickly and uniformly disengages the
socket from the work piece.
While the invention has been described in
connection with preferred embodiments, it is not intended
to be limited to the preferred embodiments disclosed but
to the contrary is intended to cover such alternatives
and equivalent embodiments which fall within the scope of
the following claims.
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