Note: Descriptions are shown in the official language in which they were submitted.
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I)OUBLE-E~DED ST~TD WITH COMBINED
DRIVING AND LOGKING MEANS
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Background of the Invention
Double-ended stud-like fasteners consisting of a machine screw
5 ~ thread on one end9 a pancake-type flange or head In the middle and a :
special thread tapplng screw at the other end are commonly u~sed in
:~ environments where the~pr~mary supporting surface is of a plastic-type
~; material with securement therein b-ing a blind application.
Typical applications of this type are those of automotive where
plastic components are provlded with boss-llke protuberances having
preformed bores ~in order to accept the tapping thread end of the stud.
The studs are usually first drivell into the plastic bosses ~ith a stud
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driver leaving the machine screw end to be inserted later through
clearance holes in sheet metal workpieces. Nuts are then used to
clamp the sheet metal against the pancake head of the double-ended
stud which puts all the load on the machine screw end of the stud and
eliminates any added stress to the plastic during installation.
A typical manner of driving such double-ended studs has been
to utilize the upwardly extending threaded shank and transmit torque
to the fasteners by means of a chuck grasping the threaded section.
Another method utilizes the outer periphery of the flange to drive the
fastener. Such applications and tools tend to be significantly greater
in diameter than the diameter of the flange and/or the boss which the
stud is to be associated with. In many such applicationsJ the bosses
are in confined areas and size of the tool is a definite factor in
efficiently driving such fasteners. -
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S In addition to the application or driving problems associated
with prior art systems, a substantial problem exists in securing the
fastener from backing out or rotation tending to remove after the
fastener has been installed. For a variety of reasons, the clamping
nuts may have to be removed and/~or the sheet metal removed from
the installation. When torque is applied to the system to remove the
nut, it is also applied to the stud tending to loosen or remove the stud
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itself~from the plastic. A~number of techniques have been suggested
to eliminate this tendency to remove the stud when the nut is removed.
Adhesives, special thread forms, locl~ing means beneath the pancake
head or a combination of special configurations of boss and pancake
head have been suggested. However, the prior art suggestions are
either costly, cumbersome or contributory to further deterioration and
stressing of the plastic during installation. -
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Summary of the Invention
The present invention is concerned with a double-ended stud
having dual purpose ribs forrr.ed on the upper surface of a pancake-
type flange and a tool for inserting such a stud in an associated work
surface. Radially extending, sharp edged~ ribs on the upper surface
of the flange function to drive the fastener and to embed in the under-
surface of a secondary work plate clamped over the stud/boss combi-
nation securing the fastener against retrograde movement of the stud.
A tool particularly designed to insert such a double-ended
fastener in a workpiece includes an end surface with a plurality of
` ~ 10 radially extending abutment surfaces formed therein adapted to engage
the ribs on the flange. An axial bore in the tool receives the upwardly
extending stud shank during the driving so that the end surface of the
tool may freely contact the flange.
In contrast with prior art methods of applying double-ended
I S ~ studs,~ the stud~ and tool désoribed herem permlt the~ axial drlvmg ~
pressure to be~ carefully controll~ed~ and conflned whlle the fastener is ~ -
stabillzed or centered m a~ properly fixtured drlvlng tool. The~ axial
drlvlng pressure~IS ~thus controlled and concentrated to m&YImlze the
efflclent application of the torque transmlttlng pressures whlch are
2 0 distrlbuted over the ~surface of the flange rather than applied to the
smaller diameter of the upwardly extending shank.
The tool~ is ~designed so that its mating end surface is sub-
stantlally equal to ~the flange dlameter of the~ stud. This allows the tool
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to be used in confined areas and eliminates any contact of the tool
with the plastic itself.
Tl1e ribs formed on the upper surface of the flange should
include at least a primary abutment surface extending perpendicular
to the flange surface and a secondary camming surface extending
toward the primary surface at an acute angle to the upper surface of
the flange. The ribs are preferably configured to permit a rotating,
mating driving tool to softly engage the primary abutment surface
and the flange to insure adequate tool life.
It is, therefore, an object of the present invention to provide
an improved double-ended stud with means to prevent removal of
the stud upon removal of a clamping nut associated thereon.
A further object of the invention is to provide a double-ended
stud with an improved means for drivlng into a workpiece. ~ -
Yet another object of the invention is to provide a double-
ended stud with a single structural improvement that serves to both
improve the driving and locking characteristics of the stud.
Yet another object of the invention is to provide a driv1ng tool
for association with the stud of the present invention and wlth fasteners
having tamperproof features.
Another object of the invention Is to provide a low profile flange
surface that provides reliable driving surfaces and minimizes driving
tool wear.
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1 In one broad aspect, the invention comprehends
a fastener r.~e~ber which includes a firs-t stud shank with a
flange extendilly radially therefrom and with the first stud
shank includin~ a helical thread formed thereon. 1'he helical
thread :incorporates means to form a mating internal thread
in a preformecl bore in all associated work surface, and the
flange defines a lower surface adjacent the first stud and
an upper surface opposi.te to the ].ower surface. An upstandi.ng
protuberance means is formed on the upper surface of the flange,
and the protuberance means includes generally radially extend-
ing ribs each having a primary rotary dri.ving surface extending
upward].y perpendicularly from the upper surface of the flanye.
An upper surface on -the protuberance formed as a first planar
surface intersects the primary rotary driving surface and
extends generally perpendicu].ar thereto, and a secondary
surface is defined by a second planar su.rface which extends
: upwardly at an acute angle from the plane of the flange. The
~: line of i.ntersection between the first and second planar
surfaces lies in a plane which extends generally tangentially
from the first stud shank toward the~primary drlving surface,
the line of in-tersection thus being disposed at an acute
:~ angle to the line of intersection between the first planar
: surface and the pximary driving surface. The fas-tener member
;~ also includes a second stud shank extending from the upper
~: .~ 25 side of the flange with the second stud shank including a
helical thread formed thereon of the same hand as -the thread
formed on the first stud shank. The protuberance means is
adapted for one-way engagement by a mating tool to rotate the
fastener member about its axis into the bo:re in the associated
workpiece, and the protuberance means further includes a -third
planar surface with the flrst planar surface intersecting the
second stud shank, wlth the thlrd planar surface intersec~ing
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1 the second planar surface along a juncture line extending
from the region of intersection between the first planar
surface ancl the second stud shank -to a point adjacent the
outer perlmeter of ~he flan~e, and with the second flat
surface extending at a lesser acute angle to -the plane of
the upper surface of the flange than the third planar surface.
Other ob~ects and advantages oE the present: invention
will become apparent from the following description and the
accompanying drawings.
o Brief Descrip-tion of the Drawing
Figure 1 is a side elevational view of the double-ended
stud embodying the features of the invention.
Figure 2 is a -top plan view of the stud as taken along
lines 2-2 of Figure 1.
L5 FicJure 3 is a side view, :i.n partial section, of the
stud member inserted in a boss surface through the use of a
particularly designed tool~
Figure 4 is an enlarged side view, in parti.al section,
of an assembly using the double-ended stud lnserted in the -~
workpiece and showing a nut member clamping a secondar~ work
plate over the flange.
Figure 5 is an end view of the tool taken from its work
contacting surface end.
Figure 6 is an elevatlonal view, in partial section, of
the tool o the invention in association with a fastener of
modified design.
Figure 7 is a top plan view o:E the fastener of modified
design shown .in Figure ~.
Figure 8 is a partial side elevational view of an alternate
embodiment of a double~ended stud embodylng the features of the
invention.
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Figure 9 is a top plan view of the stud of Figure 8 as taken
in the direction of lines 9-9 of E~igure 8.
Figure 10 is a cross-sectional view taken along lines 10-10
of Figure 9 showing the rib configuration.
Figure 11 is a cross-sectional view taken along lines 11-11 of
Figure 9 showing the rib configuration.
Figure 12 is a top plan view, similar to that of Figure 9,
showing in dotted lines various locations of recesses on a driving
tool relative to the rib surfaces.
Description of the Preferred Embodiments
Turning first to Figs. 1 and 2, the double-ended stud 10 of
the present invention will include a first, lower stud shank 12 co-
axially arranged with a second, upper stud shank 30 with an integral,
pancake-type flange 18 positioned intermediate the shanks. The
first stud section 12 is designed to be associated with a blind bore in
a workpiece structure, such as a plastic boss. With this in mind, it
is preferably provided with a thread convolution 14 of rather sharp
crested, spaced threads. A thread cutting slot 16 is formed in the
extremity of the screw to facilitate the anchoring embedment of this
flrst shank within the bore of the primary work structure. It should
be noted, however3 that even though a thread cutting slot is shown in
the preferred embodiment, a number of alternate configurations can
be used to properly form or generate an internal thread in the
primary work structure.
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A radially extending flange 18 is configured to provide a
generally flat undersurface 22, adjacent the first stud section 12,
and an upper surface 20 adjacent the second stud section 30. The
upper surface 20 includes a plurality of generally radially extending
protuberances formed on an otherwise flat upper surface. These
protuberances form an important aspect of the invention and their
dual purpose will be described in detail further herein.
The preferred embodiment of the invention shows three rib-
like members extending generally radially of the axis of the fastener.
O The rib member 24 will comprise a primary, torque accepting
surface 26, extending substantially perpendicular to the remaining
surface regions of the upper flange surface 20. The surfaces 26
will also extend radially of the axis of the fastener to achieve maximum
efficiency of the rotary force applied to the fastener. A secondary
surface 28, in the form of a ramp, extends upwardly at an acute angle
to the upper flange surface and toward the plane of the primary drive
surface 26. The camming surface 28 permits an associated driver,
such as 46, to be placed in operative position with a gradual and
"soft" engagement onto the flange surface 20. The preferred embodi-
ment discloses the camming surface as directly intersecting the abut-
ment surface 26, however it should be understood that intermediate
surfaces could be provided of any variety of configurations, such as
the embodiment of Figs. 8-12, and still come within the broad scope
of this invention.
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While the invention incorporates driving means on the upper
surface of the flange, it should be understood that the total height of
the flange and protuberances should be minimized to minimize the
space bet~een the secondary work plate be;ng secured and the primary
work structure. Such a low profile, efficient driving means is in
part obtained by a relatively large surface area of the upper flange
which cooperates with the end surface of a mating tool to align and
stabilize the tool on the fastener.
A reference to Figs. 3 and 5 will show a tool for driving the
l 0 above-described fastener and the typical application for such a fastener.
A typical use for double-ended fasteners of the type described is to
achieve a means to clamp a secondary work structure or plate-like
device to a molded plastic structure. Common applications for double-
ended studs include fastener receiving bossesl such as 34, formed in
an otherwise thin plastic structure. The bosses include a bore 38, of
a predetermined diameter. In use, the stud member lO is associated
with a driving tool 46 with the second stud section 30 received in
a bore 54 in the body 48 of the tool. The fastener member 10 may be
retained in the tool prior to driving, through the use of magnets or
the like ~not shown). Torque transmitting surfaces3 such as a
socket 56, may be formed in the extremity of the tool opposite the
work engaging ex~remity to transmit torque from a power tool to the
stud driving attachment 46. It should be noted that the diameter of
the body 48 is substantially that of the flange 18 and upper surface 36
of the boss. This dimensional relationship is permitted by the novel
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] configuration of the tool herein described and becomes important in
securing fasteners in confined regions or in an area where the center
line to center line distance between adjacent like fasteners is small.
~s best shown in Fig. 5, work engaging end surface 50 of the
tool 46 is provided with a plurality of grooves 51 equal in number to
the number of ribs 24 on the fastener. These grooves will easily
nest with the associated ribs due in part to the cooperation of the
camming ramp surface 28 of each rib with the grooves.
While the configuration of the grooves 5~ may take several
0 forms, all of them preferably will include a generally perpendicularly
arranged primary abutment surface 52 adapted for operative associa-
tion with the perpendicularly arranged primary driving surface 26 on
the fastener. The height of the primary abutment surface 52 should
preferably be at least as much as the height of mating surface 26 so
that the end surface 50 engages top surface 20 of the flange. The
engagement of the remainder of the surface 50 with the top flange
surface 20 provides an alignment and stabilization to the fastener as
it is being driven. Further attention is directed to the alignment
and stabilization provided by the telescopic association of the upper
stud shank 30 with the bore 54, which is dimensioned so that both
the length of the stud and the diameter are received therein without
abutment .
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A reference to Fig. 4 will show a second important function
of the ribs 24 on the fastener. Once the stud 10 is properly seated
on the upper surface 36 of the boss 34, the secondary plate 40 is
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positioned, preferably thlo~lgl- the use of a clearance hole, over the
stud section 30. The plate 40 is then clamped against the upper surface
20 of the flange in a mallner sho~n in Fig. ~. Tllis clampi~ achieved
through the use of a nut member 44~ The nut member 44 will typically
have the sarne hand of rotation for its internal threads as that of the
thread confi~uratioll 14 on tlle first stucl shallli wllich is drivell into
the boss 34. It should be noted that while tllè preferred embodiment
shows a machine thread 32 on the second stud section 30J that it is
conceivable that tlle stud section 30 ma~ be void of tllread~ ;lncl tllat
the nut rnernber 44 may be of a thread forming type. In any event,
the problems solved by the invention are the sameJ that being the
securement of the stud 10 from retrograde movement as the nut 44
is subjected to a torque to break the clamping~ engagement between
the nut and member 40. It shoukl be noted that upon tight clarnping
of the nut 44 against the plate 40, the sharp apex of tlle rib ''1 enlbec]s
in the undersurface of the plate in regions 42. Due to the perpendicular
arrangement of the surface 26, torque forces applied to the stud during
efforts to remove the nut, are resisted due to the lOCl;illg embèdment
of the ribs 24 with the plate 40.
While the tool of the inventioll has been described in connectio
with a double-ended stud, reference to Figs. 6 and 7 will point out the
advantages of such a tool with a fastener of modified design. Several
important features of the double-ended stud could be incorporated in
a fastener having a non-removable tamperproof head. For example,
fastener lOa is configured to have a low profile head including a
pancake-type flat flan~e ~3a an(l al~ iall~ e~!ell~ t.ll~ a(lecl Sll.
The upper surface of the l]ange will be configured wi~ll ra(liall~ e~ten(lin~
ribs 24a comprising a perpendicular dri~ lg surface ?6a and ramp
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] surface 28a permitting driving in only one direction. A cylindrical
stub shank 30a is axially disposed on the flange with side walls 32a
extending a height not substantially exceeding the height of driving
surface 26a.
The driving tool 46a can be associated with the tamperproof
fastener lOa in a manner identical to that described above relative
to double-ended fastener 10. The tool 46a is described with like
reference numerals identifying like elements to 46 with the addition
of a suffix "a". It should be particularly noted that bore 54a is
of such a diameter as to receive stub shank 30a and support the side
walls 32a therein to center and stabilize the fastener lOa during
driving. The stub shank 30a will be a height great enough to
accomplish this cooperation with the tool 46a but not so great as to
permit the fastener to be removed through the grasping of the shank
with a tool.
A further embodiment of the invention, shown in Figs. 8-12,
is configured to minimize wear of a mating driving tool. Fastener
10b incorporates an upper shank 30b, a lower shank 12b, and an
intermediate flange 18b. Protuberances 24b include a primary torque
accepting surface 26b and secondary camming surface 28b. A planar
surface 25 intersects primary surface 26b on a radial line 35 and the
upper region 39 of secondary surface 28b along a line 33 extending
generally tangentially from the shank 30b. The juncture of secondary
surface 28b and planar surface 25 thus extends at an acute angle to
the line of intersection between surface 25 and surface 26b.
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The combination of the flat surface 25 and secondary surface
28b intersecting surface 25a in a manner shown contributes greatly
to decreasing wear on a tool such as 46. As shown in Fig. 12, the
leading edge 53 of recess 51 in a tool, such as shown in Fig. 5,
is generally aligned with juncture line 33 thus creating a gradual
controlled descent of end surface 50 onto flange upper surface 20b.
I'he position of leading edge 53' in Fig. 12 indicates that continued
clockwise rotation of tool 50 still permits edge 53' to be in line contact
with camming surface 39. This soft engagement provided by the
controlled drop over the surface extent created by the small acute
angle formed between surface 39 and the plane of upper surface 20b
and flat surface 25 diminishes wear on all contacting edges of the
tool. As noted in Fig! 11, surface 39 is sloped downwardly and
outwardly toward the periphery of the flange. Such a structure enhances
~5 the soft controlled descent of the tool. Wear on tools, such as rounding
of edges, etc., becomes critical to proper functioning of this invention
because of the desire to obtain a low profile flange. Reliable positive
abutting contact between surface 26b and torque imparting surface 52
on a tool would deleteriously affect such alignment.
The flat surface will eliminate the very sharp edge contact
on the undersurface of a very thin workpanel 40 which could totally
penetrate such a workpanel. However, the right angle edge 35 and
limited surface areas of the surface 25 adjacent the outer periphery
of the flange 18b will still permit the partial embedment and locking
feature shown generally in Fig. 4.
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~';econd~r ~, s~ ce :~b 111.~' bc C()ll~ e(l ~ .l il ol' ill~
sect;ng carlnming surfaces exten(ling at difrerent acute allgles from the
upper surlace 20b. ~ camming surface 37 ~nay be :formed to inter-
sect surface 39 with SUrïclCe 3~ inter9eCtil~g the r~at SUrf;lCe 25 alOtlg
line 33 and lower s~lrface 37 intersecting the flange upper surface 20b.
Surface 37 will be at a greater acute allgle to surïace 20b than surface
3~ perlnitting tl~e tool to gl~acluall~ de9c~ (1 down\~ldl~. .';u~ e ~3~
contributes to ~strerlgtll of the protuberance ancl e:fricient mallu:racture
thereof .
]o Thus there is shown and described a double-ended stud which
includes novel driving surfaces which also function as a means to lock
the fastener frorn removal as the nut member is loosened ther efronl.
In adclition, a particularly deslgned tool is shown for accornplishing
the driving of a fastener into a work surface.
lS While particular embodiments of the present invention have
been shown and described, it will be obvious to those skilléd in the
art that changes and modifications may be made without departing
from this invention in its broader aspects and, therefore, tlle aim in
the appended claims is to cover all such changes and modifications
as fall within the true spirit and broad scope of the invention,
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