Note: Descriptions are shown in the official language in which they were submitted.
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The invention rleates to an arrangement for ef-
fecting a very rigid connection between relatively thin
sheet material and a heavier member. A typical example of
such a structure in the connection between fan blade members
and the like, with a central hub member, by means of which
the blade member is adapted to be connected to a rotatable
drive shaft or the like. Other examples of this type of
structure are for bushings, sleeves, and various types
of fasteners.
For the purpose of illustration, the invention
will be described and explained in connection with the
connection of relatively thin an blade members with a
relatively heavy hub member, where problems of torque trans-
mittal are involved.
It is common practice in the construction of
fan blades and the like, having a central hub member, to
secure a tubular-shaped hub member to a flat sheet-like
central hub receiving portion of the fan blade or other
structure, by forming the hub member with an axially
extending sleeve adapted to be inserted into a bore in
such central hub receiving portion of the blade member,
with the sleeve having an outer diameter approximately
equal to the diameter of the central bore of the blade
member. The hub member is provided with an outwardly
extending shoulder at the inner end of the sleeve, upon which
the adjacent face of the blade member abuts.
The sleeve of the hub member is designed with
such a length that, following insertion in the bore of the
blade member, it may be suitably formed, as for example
by a swaging or spinning operation, or the like, into an
outwardly extending flange which overlies the peripheral
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portions oE the blade member defining the bore therein,
thus clamping the blade member between the shoulder and
flange of the hub mem~er.
While such clamping action may, at least initial-
ly, firmly clamp the hub and blade mernbers, often following
use, the blade member may become relatively loose on the
hub member and the frictional engagement between the two
parts, which must carry all torque forces transmitted
~ by the hub to the blade member,become reduced to a point
; 10 where slippage may take place therebetween.
While it is possible to form the hub member with
a central bore which includes one or more integral keys or
splines, adapted to cooperate with corresponding splines
initially on the hub member, the fabrication of the indi-
vidual blade and hub members with key or spline configura-
tions becomes relatively costly and thus increases the cost
of the assembly.
Problems such as this are solved in the present
invention by employing a blade member or the like, of
2~ relatively soft sheet material, for example aluminum, which
has a circular bore therein adapted to receive a relative-
ly smooth-wall sleeve formed on a hub member of relatively
harder material, for example, a suitable steel. The latter
is provided with a shoulder disposed adjacent the inner
end of the sleeve, upon which the adjacent face of the
blade member is adapted to abut, with the shoulder being
radially outwardly spaced from the outer face of the sleeve
by an axially extending annular groove having a radial
width which is approximately equal to the thickness of the
material of the central portion of the blade member.
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Following such assembly of the blade members, the
free outer end of the sleeve is deformed by a shearing
action to divide the slee~e into a plurality of axially
extending segments, alternate segments of which are flared
outwardly into engagement with the periphery of the central
bore in the blade member, while the intermediate segments
are deformed or bent over, biting into the relatively soft
. material of the blade member to deform the engaged material
. .,
of the blade member into the groove, which preferably has
a depth approximately equal to the thickness of the
material of the blade member, whereby the deformed portions
of the latter will seat on the bottom oE such groove.
~ Such intermediate segments thus form splines which in
; the deormation of the adjacent material o the blade
member, form cooperable grooves therein, in which such
segments are disposed.
The hub member thus, in e~fect, is splined to
~; the blade member and at the same time the latter is pro-
vided with flange portions extending transversely to the
general plane of the blade member, providing additional
rigidity in the blade.member at the hub member, with
the bent or waged over portions of such intermediate seg-
: ments securely clamping the blade member in rigid engage-
ment with the hub member.
An extremely rigid and efficient connection i9
thus provided between the blade and hub members.
It will be apparent that the same basic
construction can be employed with structures in~olving
relatively thin sheet material, for example securing
threaded fasteners, bushings, etc. to shee~ material
boards, etc.
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ON THE DRAWINGS
In the drawings wherein like references indicate
like or corresponding parts:
: Fig, 1 is a side elevational view of a fan blade
structure mounted on a motor driven shaft;
Fig. 2 is an axial sectional view of a hub
member and a portion of a cooperable blade member, prior
to assembly;
Fig. 3 is a top plan view of the completed
assembly;
Fig. 4 is à sectional view taken appro.~imately
- on the line IV-IV of Fig. 3; and
Fig, 5 is a sectional view taken approximately
on the li~e V-V of Fig, 3.
Referring to Fig, 1, ~he fan blade structure,
indicated generally by the numeral 1, comprises a blade
member 2 having a central portion 3 from which extend a
plurality of blades 4. Connected to ~he central portion
3 is a hub member 5 by means of which the blade structure
may be mounted on the drive shaft 6 of a motcr 7.
A large number of blades of this type are
constructed from sheet metal suitably configurated and
bent to form the blade member, to which is secured a
separately formed hub member 5.
Referring more particularly to Figs 2 through 5,
the hub member 5 is provided with a cylindrical tubular
body portion 8 having a central bore 9, adapted to receive
the drive shaft of a mo~or or other driving means, with the
member 8 having relatively thick walls 10 in which is
threaded a set screw 11, by means of which the hub may be
locked to a shaft inserted in the bore 9. Integrally formed
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with the body portion 8 and extending in an axial direction
from one end of the latter ls a coaxial sleeve 12 which is
relatively thin in radial thickness as compared with the
corresponding thickness of the body portion 8, with the
outer diameter of the sleeve being approximately equal to
the diameter of the bore 13 in the central portion 3 of the
blade member 2, whereby the sleeve 12 may be readily inserted
into and snugly fitted to the bore 13, The body member 8
is also provided with a radially extending shoulder 14
disposed adjacent the inner end of the sleeve 12 and
spaced therefrom by an annular groove 15, the radial width
of which is approximately equal to the thickness of the
central portion 3 of the blade member,
In assembling the blade and the hub members, the
sleeve 12 of the hub member is inserted into the bore 13
wi~h the bottom surface of the central portion 3, as viewed
in Fig. 2, seated on the shoulder 14, after whîch by means
of a suitable tool, a plurality of shear cuts are formed
in the free end of the sleeve 12 to divide the same into a
plurality of axially extending segments 16a and 16b. The
alternate segments 16a are deformed slightly to provide a
flared configuration, as illustrated in Fig. 5, whereby the
outer surface of such segments are brought in~o finm
engagement with the peripheral edge of the bore 13
but insufficient to materially deform the peripheral portion
of the blade member. The intermediate segments 16b, how-
ever, are deformed to a considerably greater extent than
the alternate segments 16a, whereby such intermediate
segments are bent over toward and engage the adjacent upper
face of the central portion of the blade member, as viewed
in Fig. 4.
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As previously mentioned, the blade member 2 is
formed from a relatively soft material, while the hub
member 5 is fo~ned from a relatively harder material,
whereby upon bending over of the segments 16b, the
latter will be forced into the material of the central
portion 3 shearing the latter along the side edges of
the segments and flowing the material of the blade member
into the groove 15 as indicated at 17.
The staking or swaging operation described may
be performed in a single step, or in two steps, depending
upon the configuration of the tooling employed in con-
nection therewith.
It will be appreciated that the segments l~b
and the grooves or channels formed in the central portion
3 of the fan blade member, as a result of the deforming
of the segments 16b produced, in effect, a splined connec-
tion between the blade and hub members that will provide
a very durable and strong connection therebetween that will
withstand any torque stresses that may be transmitted from
one to the other. Likewise, the bent~over portio~s 17,
of the central portion 3 of the blade member, form indivi-
dual flanges seated in ~he groove 15 thus tending to stif-
fen and add further rigidity between the two members.
The alternate segments 16a preferably are deformed merely
sufficiently to firmly engage the peripheral edge of the
bore 13 but insufficient to ma~erially cut into or shear
the central portion 3 to insure the retention of an
adequate spline interposed between adjacent s~gments 16b.
It will be appreciated that if all of the segments were
3~ completely bent over co~rresponding to the segments 16b,
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the central portion 3 would be relatively uniformly
deformed thereby obliterating the spline configuration
and thus reducing the torque-transmission capabilities
of the structure.
The proportioning and number of segments 16 will,
of course, depend upon the size of the hub member, the
thickness of the central portion 3 of the blade member,
etc. and could, for example, follow normal spline propor-
tioning in correspondence to thecharacteristics of the
materials from which the respective members are constructed.
Instead of the member 5 as a hub member, it could
serve as an internally threaded bushing, standarded, panel
fastener guides, etc., all o~ which may embody ~he inter-
locking structure. Likewise, depending upon the applica-
tion, the heavier member may be in the form of a bar
member, rectangular or frame members of other
configuration.
It will be appreciated from the above disclo-
sure that the present invention provides a strong
durable mechanical interlock between two members, in par-
ticular hub and blade structures, thereby not relying
solely upon frictional clamping forces, etc.
It will further be appreciated that the present
invention in effect provides a splined connection be~ween
the two members without requiring initial formation
of splines and the like in the two parts which are to
be subsequently assembled, thereby eliminating relatively
costly tooling and enabling the blade member to be formed
with relatively simple stampi~g dies, etc., and the heavier
member, when in the form of a hub member, bushing or
similar member, to be readily manufactured by automatic
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,
screw operations and the like.
. Having thus described my invention it will
be obvious that although various minor modifications might
be suggested by those versed in the art, it should be
understood that I wish to em~ody within the scope of the
patent granted hereon all such modifications as reasonably,
and properly come within the scope of my contribution to
the art.
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