Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3~6
This application relates to a method of thickening sheet
metal ln selected areas. In a more preferred embodiment, this
application relates to a method of making pulleys from sheet metal.
The method of making pulleys from sheet metal has long
been known. Such pulleys are often made by a metal spinning pro-
cess, such as that shown in Wickwire et al, U.S.P. 2,685,856, dated
August 10, 1954, or Harrison et al, U.S.P. 1,828,464 dated October
20, 1931. Both of these patents show making of pulleys with a
single v-groove, which can be used to contain and provide power to
a v-belt. It is possible also to make pulleys having two v-shaped
grooves by a metal spinning process, as shown in U.S. Patent
2,892,431 of Killian et al, dated June 20, 1959. However, this
involves more complicated machinery, and is also sub~ect to diffi-
culty because the formatioh of the v-grooves causes metal flow,
leading to thinned portions of the pulley wall around the v-grooves
which may lead to failure of the pulley in operation.
It has been proposed to form pulleys having more than two
v-grooves by the use of metal dies, as has been disclosed in U.S.P.
3,368,376 of Previte, dated February 13, 1968. However, this pro-
cess wculd require complicated dies with expanding arcuate segments.Another process, which involves the spinning of shallow grooves
which are folded together into a sinuous shape and impressed with
a v-grooved roller, has been proposed in U.S.P. 3,977,264 of Sproul.
This process also involves expanding die segments and complicated
equipment, and requires that very thin grooved metal be precisely
folded together without tearing. Insofar as applicant is aware,
neither the Previte nor the 5proul process has been used commer-
,
cially.
The formation of v-grooves in the side of a pulley in any
30 of the aforesaid processes can lead to thinning of the pulley wall,
and therefore failure of the pulley. One reason for this is that
a considerable amount of metal ~low must necessaril~ occur in
.~ .
~g43~l6
these processes, and it is difficult to guide this flow in such
a way that all portions of the finished v-groove in the pulley
are of ade~uate thi~kness. Accordingly, it is necessary to start
from a fairly heavy gauge metal, so that the final pulley will
be of sufficient strength to resist the torsional stresses which
would tend
~ ~
": '
- la
to drive it out-of-rouna in operation.
~ The existing spun pulleys have been usable with respect
to single v-belts, which are belts having one flat side and
one siae shaped in an outwardly pointing vee configuration. How-
ever, for many years, other belts, known as poly v-belts,have been
used in a number of operations, such as for the powering of speci-
alized machinery~ These belts have one flat side and a plurality
(usually six) of vee portions extending outwardly on the oppos~te
side, in a saw-tooth pattern. The pxoduction of p~lleys to engage
such belts has been difficult, as the saw-tooth like configuration
of a poly v-belt requi~es a number of sharply pointed vee config-
uarations on the pulley, in relatively close proximity to one an-
other. This uses up a great deal of metal. Accordingly, a rela~
tively thick walled pulley can must be used if traditional metal
spinning techniques, or a die stamping technique such as that of
Previte,is to be employed. The resulting pulleys would be h6avy
and expensive to make, and have not found favour in automobile
~anufacture, where low cost and weight reduction are desirable
for commercial acceptance. The lack of effective, low cost, light-
weight pulleys has prevented the widespread adoption of poly v-
.. . .
~ belts by the automob~le industry, despite other inherent advan-
-~ tages which have been recogniæed for such belts.
: . ,
-~ In most spinning or aie-stamping methods, the pull~y
blank is formed initially by drawing a flat piece of metal into
a shape having a base and an ups~anding cylindrical wall. This
blank is commonly known as a "cann. The pulley grooves are rolled
or die-stamped into the wall of the can. Accordingly, the initial
flat piece of metal must be chosen to be of a sufficient thickness
so that the can wall, after drawing, is of sufficient thickness to
make ~-grooves of adequate strength for the intended application.
However, the drawing process produces a wall which is either the
same thickness as, or slightly thinner than, the base~ Accordingly,
315~i
in the present processes, the minimum thickness permissible for
the starting piece of metal is determined by the minimum thickness
tolerable in the walls of the can. As the can base is subjected
to lesser stresses than the wall during formation of the pulley,
it need not be as thick or strong as the wall. It would there-
fore be advantageous in many cases, from a cost point of view,
to provide a pulley can which has a strengthened wall.
Accordingly, it is the object of the present invention
to provide a method for strengthening the approximately cylindrical
wall portions of a pulley blank or "can" so that the wall portion
will be more robust than would otherwise be possible with the
thickness of sheet metal used to form the pulley can. It is -
another object of the invention to prepare pulleys having at
least four v-grooves in their sides, such v-groo~es having rela-
tively sharp bottoms to their vees. It is another object to form
a generalized method of thickening the sheet metal of vertical
walls of a drawn can, so as to stren~then the vertical upstanding
walls. It is another object to provlde light-weight, strong
pulleys for the purpose of powering poly v-belts in automobiles.
Having regard to these objects, the invention in one of
its aspects comprises a novel sheet metal pulley comprising a
circular sheet metal base of sheet metal having a predetermined
thickness, a cyl~ndrical wall upstanding from the base and formed
from the same piece of sheet metal as the base, said wall having
a smoothly cylindrical inner surface and an outer surface having
at least four parallel ~T-shaped grooves, separated by projections,
extending around the cylindrical wall at right angles thereto; a
first annular flange formed from the same piece of sheet metal as
the base and extending outwardly from the wall at the point where
the wall joins the base; a second annular flange formed from th~
same piece of sheet metal as the wall and base extending out-
wardly from the end of the wall remote from the base, said
- 3 -
~09~3~i6
annular flanges defining the ends of the outer surface of the
cylindrical wall.
Another aspect of the invention provides a novel method
of forming a pulley, which comprises: providing a pulley blank
formed o~ sheet metal and having a circular base and a cylindri-
cal wall upstanding from the circumference of the base; contacting
the upstanding wall with a first roller, said first roller having
a main face and receding sloping faces at each end of the main
face, while said pulley blank is rotatably retained in apparatus
having sloped faces to coact with the sloped faces on the roller;
rotating at least one of the roller and the pulley blank, said ,
roller and said pulley blank being contacted with sufficient
force such that both rotate, while moving the roller inward, ~
whereby said main face of the roller defines a wall in the ' '
pulley blank and the coacting sloped faces on the apparatus and
roller define upper and lower flanges bounding said wall;
partially, but not completely, collapsing said wall in an axial
direction; providing a cylindrical backing block of smaller
diameter than the pulley blank within the pulley blank; contacting ':
.. .. . ... .. .. . . .. . ... ... . . .. . . . ...
the exterior of the partially collapsed wall with th,e face of
a second roller to form the blank into a pulley, said roller and ;:,
said blank being rotatable and said backing block being rotatable ,:
-~ with the blank, and one of said blank and said roller bein~ caused
to rotate, said roller and said blank being contacted with suf-
ficient force such that both rotate, while moving the roller in-
wardly to a predetermined distance from the backing block, whereby ;~
-~ the roller deforms the metal of the wall completely filling the
: space between the roller and the backing block forming a smooth
cylindrical interior wall when such roller is at the predetermined
distance from the backing block.
The second roller as described above can be smoothly
c~lindrical and the predetermined distance can be greater than
- 4 -
the thickness of the metal of the base, whereby a smooth-walled
pulley with a robust wall thicker than the base and bounded by
two flanges is obtained. In another embodiment, the second roller
can have circumferential ridges whereby to impart a poly-v groove
pattern on the face of the pulley between the flanges. In this
case, the predetermined distance (between the part of the roller
most closely approaching the backing block to the backing block)
can be less than the thickness of the sheet metal of the pulley
can, while still giving adequate strength.
In another embodiment, a smooth-walled pulley with a
thickened wall is first formed, then this is contacted with a
roller having circumferential ridges to give a poly-v grooved
pulley.
The invention will be further described with respect
to the drawings in which:
Figure 1 represents a sheet of sheet metal which is
usable to form a pulley can.
Figure 2 is a cross-sectional view of one form of a
pulley can formed from the metal of ~?igure 1.
Figures 2a and 2b show bross-sectional views of alter-
; nate forms of the base of the pully can.
Figure 3 shows a cross-sectional view of the pulley
can of Figure 2 mounted in a conventional metal spinning apparat-
us .
Figure 4a shows a partial cross-sectional view of the
can of Figure 2 and Figure 4b shows a partial cross-sectional
view of the sa~e can, illustrating a flange-forming step which
can optionally be performed prior to partial collapsing of the
can.
Figure 5 shows a partial cross-sectional view of the
can of Figure 2, showing one method of collapsing the can par-
tially.
_ 5 _
3~i;6i
Figures 6a and 6b show a partial cross-sectional view
of the can of Figure 2, illustrating successive steps of an
alternative way of collapsing the can partially.
Figures 7a and 7b show successive steps in the form-
ing of v-grooves in a partially collapsed can.
Figures 8a and 8b show successive steps in thicken-
ing the walls of a partially collapsed can without forming
v-grooves.
Figure 9 shows the formation of v-grooves in a can
after the step of Figure 8.
In its simplest Eorm in manufacturing a pulley suit-
able for poly v-belt use on automobiles, a pulley can is formed
by deep drawing or spinning, in a conventional way, a sheet of
flat metal. The particular sheet metal can be any of those
conventionally used in spun pully manufacture. The most common
of these are sheet aluminum and hot rolled, commercial quality,
low carbon sheet steel. The sheet of sheet metal, s~lch as
` shown in Figure 1, has for example a thickness of 0.080 inch.
Thicker sheet metal can of course be used, and the upper limit
to thickness depend5 upon the ultimate use envisaged for the
pulley to be made, and the pressures able to be exerted by the
drawing and spinning equipment to be used. The use of thin
sheet metal (i.e., between 0.070 inch and 0.110 inch in thick-
ness) is preferred as the particular advantages of the present
~ invention are much more pronounced when thin sheet metal is used,
: as then the invention provides pulleys from such thin sheet metal
which have performance characteristics which could otherwise
have only been obtained from pulleys made of a thicker grade of
the particular sheet metal.
As stated above, a pulley blank (which is henceforth
called a "can") is made according to conventional methods on a
conventional deep drawing or rolling machine. Such a machine
stamps a circular portion out of a sheet of sheet metal 1
-- 6 --
(Figure 1) and draws it into a can having a base, and an upstand-
ing cylindrical wall. The can may be of any desired dimension,
depending upon the size of the e~uipment being used, and the
size of the required final pulley. For example, for six inch
pulleys (a size often used in automobiles) a circular piece nine
inches in diameter is stamped out, and is drawn into a can with
a ~.6 inch diameter base and a two inch high wall. A typical can
is shown as 15 in Figure 2. The can of Figure 2 has a stepped
base portion 10 and upstanding cylindrical wall 11. The base
10 portion 10 is usually pierced in its center by a hole at 12 in ~`~Z
conventional manner, to provide for registration on metal spin- ~-
ning equipment. Other holes may be pierced for registration
purposes or for use as bolt holes when the pulley is completed.
Additionally, the shape of the base 10 of the can need not be
stepped as shown in Figure 2, ~ut may instead be of flat or
sloped configuration as shown in Figuxes 2a and 2b. Instead of
a single hole, several holes may be pierced in the base in any
desired pattern, as shown at 13 in Figure 2b~ If desired, the
pulley blank may be fitted with a hub formed of a separate piece
20 of metal, as for example shown in United States Patent 2,696,740
issued December 1, 1954.
According to the method of the invention, the can is
placed in a conventional, general purpose, metal spinning machine.
Such machines are available commercially, and will not be illus-
trated here. As is usual, the machine is provided with chucks to
hold a workpiece for rotation and with tool holders to move sel- -
ected tools toward and away from the axis of rotation of the
work-piece. The machine is also capable of compressing a work-
piece along its axis of rotation.
Figure 3 shows a can of the form of Figure 2 positioned
in a metal spinning machine between bottom chuck 20, and top
chuck 23. The axis of rotation of the can is shown by the line
-- 7 --
~0~356
a-a through the chucks and the c~n. As is common in the pulley
spinning art, the can is correctly oriented so that its axis of
rotation is the centre axis of the cylindrical can wall. Such
orientation can be achieved by means of a can holding groove 21
in the bottom chuck 20, and a central spindle 24 extending from
chuck 23 and engaging hole 12, or by any other known means. ~`
If desired, cylindrical internal support block 60 may
be secured to the chuck 20 for rotation therewith. The block 60
has an indentation 61, to house spindle 2~ when chucks 23 and 20
~ 10 are moved together a predetermined distance.
`~ It is preferred, for reasons to be described later,
that the inner side of groove 21 be sloped, rather than vertical,
~ as indicated at 25 in Figure 3. Top chuck ~3 also has a sloping
; annular portion 26 facing the slope 25, also as shown in Figure
.
If desired, a step of forming outer and inner 1anges
in the pulley wall can be carried out before thickening of the
wall and forming the grooves in it. Such a step is not absolutely
necessary, as flanges can conveniently be formed during the course
of subsequent steps of pulley formation, as will be described.
; However, it is sometimes convenient to form the flanges first,
as this may permit better control of the partial collapse of the
pulley wall, as described later.
- 7a -
.: ` ~ ; ;
~ ~O~q~3~ii ~ .
The step of flange formation is shown in Figures 4a and
4b. Fi~ure 4a shows a can positioned as shown in Fiyure 3, but
with a roller 50 approaching it. The roller 50 is rotatablP about
an axis c-c parallel to a-a and is movable toward and away from
axis a-a. The roller 50 has a generally cyllndrical smooth outer
face 51, and two sloped portio~s 52 and 53 each adjacent to the
cylindrical face 51 as shown in Figure 4a. Alternately,-the face of
the roller can be slightly concave if desired. As is known in ;~~
the art, such a roller can be mounted on springs, so that it can
move axially up and down slightly in response to pressures on its
1~ periphery. In the example shown, the roller is unpowered.
The chucks 20 and 23 are rotated simultaneou$1y, at the
same speed and in the same direction, carrying with them the can
15 and block 60. As this rotation is occurring, the roller 50 is
` moved into contact with the wall 11 of the can 15. Simultaneously,
t chuck 23 is moved downwardly a predetermined distance, so that, as
the face 51 contacts the can wall :Ll and continues to move inwardly,
the metal at the ]oin between base 10 and wall 11 ~shown at 16)
is folded over by the pressure of the xoller 51 bearing against the
I can. The sloping portion 52 of the roller helps fold over the
20 metal at 16 smoothly, to form a flange. Similarly, the sloping
portion 53 helps form a flange smoothly at the end 17 of the can
wall which is most remote from the base. The roller 50 is mv~ed
; inwardly toward the axis a-a a predetermined amount, having regard
to the amount of downward movement of the chuck 23, so that the
areas 16 and 17 of the wall 11 are folded into the position ~hown
in Figure 4b, without undue stretching. Preferably (but not nec-
essarily) the internal block 60 extends outwardly just sufficiently
so that its external face 62 provides a backing support for the
wall 11, when the roller 50 is at the innermost limit of it5
30 travel toward the axis a-~. It is preferred, however, that the
block 60 should be of such a height that there is a gap, indicated
.. , , . . _ .
a3 63 between the base 10 and the block 60 after this operation,
-- 8 --
so that the chuck 23 can be moved in subsequent steps of the pulley
formation closer to the chuck 20, without the necessity of changing
blocks 60. Ho~ever, instead of leaving a space 63, it is also
possible to dispense completely with the block 60 during the step
shown in Figures 4a and 4b, or else, after completion of the step
shown in Figures 4a and 4b, to remove the block 60 and replace it
with a block having a smaller vertical height, before going on to
further steps.
The steps shown in Figures 4a and 4b creat~ two ~langes,
18 and 19, with a flat portion 117 between them. It will be noted
that the flange 19 lies along the sloping portion 25 of the chuck
20 and is in fact formed between the sloping portion 53 of the
roller 50 and the sloping portion 25 of the chuck 20. The slope
of portion 25 should be pre-chosen so that it will provide a smooth
back to assist in formation of flange 19.
As stated above, the step shown in Figures 4a and 4b is
optional. It has the effect of accurately sizing two flanges 18
and 19, which flanges are found to be useful in pulleys for poly
v-belts, as they help to retain the poly v-belt in position when
the pulley is ultimately formed. In the subsequent ~escription,
it will be assumed that the step of flange fo~mation as shown in
- Figures 4a and 4b has not been carriea out, but it will ~e under-
stood by one skilled in the art that the steps to be described can
be carried out with a pulley blank`having flanges 18 and 19 as
ob~ained from the carrying out of the steps shown in Figures 4a
and 4b.
If the step of Figures 4a and 4b is not carried out,
the first step to be performed on a pulley can in the process
according to the invention is the partial collapsing of the wall
11 of the pulley can 15. Such partial collapsing can be carried
out in several ways. One way (which is not preferred) is by a
step of bulging the can as shown in ~. S. Patent 2,929,345 of
_ g _
~ ' ,
~ ~9~L3S;~;, ~. ~
Zatyko, dated March 22, 1960. This step is not preferred as it
requires special equipment, which must be specially mounted on the
spinning machine for the purpose of the step, and subsequently
removed so that other steps can be carried out. An alternative,
and also not preferred manner, is simply to apply axial pressure
to the chuck 23, causing the wall 11 to buckle, as shown a~ 112
in Figure 5. The buckling occurs in an irregular manner. The
block 60 need not be present ~uring the operation of partial col-
lapse of the wall 11 to the approximate shape shown at 112, but it
can be present if desired. As will be obvious to one skilled in
the art, the irregular buckling could also be carried out after
~- flanges 18 and 19 have been formed by the method shown in Figures
4a and 4b.
An alternative, and preEerred manner of partially
collapsing the wall 11 is shown in Figures 6a and 6b. Figures 6a
and 6b show a pair of rollers 31 and 32, which rotate about an axis
b-b. These rollers are separated from one another b~ a compression
spring 33. Each of the rollers has a face with a sloping portion
34, a blunt extension 35, and a curved portion 36, which is lo-
cated nearest the other roller. The two rollers are separated by
~ the spring 33 a distance such that the projections 35 will engagewall 11, when the rollers 32 and 33 are moved to~ether toward the
wall, at fairly widely spaced points on wall 11.
In the partial collapse of the can wall according to the
.
method of Figures 6a and 6b, the chucks 20 and 23 are powered to
rotate the can 11, and the rollers 31 and 32 are moved into contact
with the can 11. As the rollers contact the can 11, they will of
course begin rotating as well, as the rotation of the can 11 will
cause them to xotate. The projections 35 will of course be the
first portions of rollers 31 and 32 to contac. the can wall 11.
As soon as the portions 35 have contacted the wall, the chuck 23
is moved toward the chuck 20, at the same time as the rollers 32
3~;6 , ~ .
and 31 are moved togethPr toward the axis a-a. This will cause
the can wall 11 to buckle, and, at the same time, the buckling
will be controlled somewhat by the fact that the projections 35
will tend to stay in contact with the same portion of the can
~all that they originally contacted,with the spring 33 compressing
as the chuck 23 moves toward the chuck 20. This will cause the
; can wall to lie along the contour of the curved roller face 36,
as shown in Figure 6b. The amount by which the rollers 31 and 32
should approach the axis a-a, and the design of the contours 36
and the amount of movement of the chuck 23 will be obvious to a man
skilled in the art. It is generally preferred to have the rollers
31 and 32 end up in face to face contact with one ~nother, so that
no point or burr on the metal is formed by a gap between the two
faces 36~ such as indicated at 37. However, if a burr or point i-R
formed, this is not detrimental, as lt will be removed during the
later processing steps. After the rollers 31 ana 32 are withdrawn
further controlled collapse can be carried out by moving the chucks
20 and 23 c~oser to one another by a desired amount.
The form of partially collapsed wall formed by the
method of Figures 6a and 6b is shown in Figure 6b at 113. It
will ~e noted that the shape of the collapsed wall is somewhat
more regular than is formed by the method of Figure 5. Herein-
after, further steps of the invention will be described with
respect to a wall of form 112, but it is understood that thi~
disclosure applies equally to a wall of form 113.
No matter which method is used to collapse the wall, it
is preferred that the wall 11 be collapsed so that is final height
(hl)(see Figure 5) is from 25~ to 75~ of its original height h
(see Figure 2~. If a flange has been formed by the step of Figure
4 prior to the collapse, the ncollapsed" height hl includes the
height of the flanges 18 and 19. Conveniently, the height of
block 60 is such that, after collapse has occursed by the desired
amount, the block is in contact with the base 10 of the can, as
shown in Figures 5 and 7a~ ~
. ,
3~6 ~
, ~
Once the wall has been collapsed into the shape 112 or
113, the operator can, according-to the invention, either perform
on it the steps of Figures 7a and 7b to obtain a final pulley
suitable for US2 with a poly-v-groove belt, or else the steps
of Figures 8a and 8b to obtain a pulley having a thickened up-
right wall and which is suitable for use with a flat belt. If
the steps of Fi~ures 8a and 8b are carrie~ out, a subsequent step
can (if desired) be carried out as is shown in Figure 9, to con-
vert the pulley thus fonned into one suitable for use with a poly
v-belt.
Referring now to Figures 7a and 7b, one method of for-
ming a pulley suitable for use with a poly v-belt from a col-
lapsed can having the configuration 112 or 113, will now be des-
cribed. Figure 7a shows a roller 40, which rotates about an axis
d-d, parallel to the axis a-a. The face of roller 40 is provided
with a number of sharp projections 41, spaced from one another
by v-shaped indentations 4~. The number and shape of projections
41 is the same as the number and shape of projections on the poly
v-belt with which the pulley to be made is intended to be used.
In the example shown in Figure 7a, there are six projections 41
separated by five indentations 42, in the sa~e configuration as
is used in a common type of v-belt. The top of the roller 40 has
a sloped transition surface 43 between its face and its top.
Similarly, there is a sloped transition surface 44 between the
face and the bottom of the roller.
The chucks 20 and 23 are set into motion simultaneously
and in the same direction, causing the partially collapsed can
to rotate. The axis d-~ is then moved toward the axis a-a. ~en
the face of the roller 40 comes in contact with the can, the roller
also begins to rotate~ The surface 43, as it engages the can,
squee~es a portion 114 of the met~l of the can wall against the
sloped surface 26 of upper chuck 23, forming a flange~ Similarly;
12 -
~ . .
~Cl1!9~35~
the sloped surface 44 squeezes a portion 115 of metal against
the sloped surface 25 of bottom chuck 20, forming a bottom
flange. These two flanges are identical with the flanges formed
at 18 and 19 in the step described with respect to Figure 4. If
the step of Figure 4 has been carried out, and the flanges are
already formed, the sloped portions 43 and 44 merely nest
against the pre-existing flanges, and do little if any deforma-
tion of metal.
The sharp projections 42 cut into the metal of the can -
wall 112, and deform it. If the can wall were not partially col-
lapsed, i.e., if it were in the same state as is shown in Figure
2 at 11, the sharp projections would cut deeply into the thin
sheet metal of the wall. If the sheet: metal were relatively
thin, i.e., below about .110 inch, ancl the depth of the inden-
tations 42 from the projections 41 was approximately .125 inch,
insufficient metal would flow into the indentations 42 to fill
such indentations before the sharp projections 41 cut entirely
through the metal o~ wall 11, or else approached so nearly to
cutting through the wall as to render the wall 11 extremely weak.
However, according to the method of the invention, the collapsed
portion 112 of the wall provides more metal than a straight
cylindrical wall would do. This gives sufficient metal, even
when sheet metal of initial thickness of 0.080 inch is used, to
fill completel~ 0.125 inch indentations at 42, while still re-
taining a strong wall.
The roller 40 is moved towards axis a-a until the in-
dentations 42 have all been filled with metal. The final form
of the can wall is shown in Figure 7b. It will be noted that
there is an appreciable thickness of metal indicated by the
distance y between the points 41 and the inside 116 of the
can wall which now rests firmly against the exterior wall 62
- 13 -
~9~3Si~ii
of the backing block 60. The indentations 42 are fully filled
with metal of the wall, as shown by the dimension x. Generally
speaking, where the height h, is from .25 to .75 of the height
h, a thickness of wall plus projections (dimensions y plus x
in Figure 7b) of from about 1.5 to 2.5 of the thickness of the
original sheet metal can be obtained for sheet metals in the
thickness range of about .070 inch to 0.130 inch. The relative
size of dimensions y and x will of course depend on the size,
shape and number of projections 42, and upon how close to the
wall 62 and the roller 40 is allowed to approach. In order to
obtain a strong pulley for use in an automobile, the roller 40
is allowed to approach the wall 62 only closely Pnough so that
the minimum wall thickness 7 will be 0.040 inch. A smaller
minimum thickness would of course be permissible if the pulley
were designed for uses requiring less strength.
During the operation of Figure 7, the backing block
60 is extremely important, as its wall 62 assists in distri-
buting the metal of can wall 112 so that it fills all of the
indentations 42.
2a
- 13 - (a)
.
.
.
~; After the roller 40 has come to the position of Figure
7b, it is removed, and the pulley can, which has now been fully
formed into a pulley suitable for use with a poly v-belt, is
removed. It will be noted that the pulley thus formed has two
flanges, 18 and 19, ~Jhich give it considerable dimensional stabil-
ity, and has a series of grooves (the mirror image of projections
41 and indentations 42 of the roller) for use with a poly v-belt.
An alternative arrangement, for use in making a pulley
with a fl~t face, is shown in Figures 8a and 8b. Turning first
to Figure 8a, a roller 70, rotating around an axis e-e which is
i parallel to axis a-a is shown. This roller has a flat face 71
and two sloped portions 72 and 73. Portion 72 joins thè flat
face 71 to the top of the roller, whereas portion 73 joins ~he
~; flat face to the bottom of the roller. The width of the face 71
is just slightly smaller than the width of the face 62 of backing
block 60, and the slope of the sloped surfaces 72 and 73 are
chosen having regard to the slopes of surface 2~ and 25 with which
they will C0-2Ct to form flanges.
The chucks 20 and 23 are caused to rotate simult~r.eously
and in the same direction, carry;~g the can 20 with them. The
axis e-e of the roller 70 is caused to move toward the axis a-a,
~ith t~e roller oriented opposite the can as shown in Figure 8a.
`~ The flat face 71 contacts the collapsed portion 112 of the can -
wall, pushing it against wall 62 of backing bloc~ 60. Simulta-
neously, sloped surface 72 of roller 70 squee~es a portion of the
metal of the can wall ag~inst surface 26 of chuck 23, to form a
flange, and surfacP 73 squeezes a portion of the metal of the
3D can wall against sloped surface 25, also forming a flange~
Because of the bulged or partially collapsed surface of the wall
of the can, ~here is more metal than would be needed merely to
.
1~ .
3~S
make a flat wall of the same thickness as the metal of the base.
Thus, when the roller 70 approaches the wall 62, a thick, smooth
wall of metal 111 is formed, having smooth surfaces against
faces 71 and 62. The advance of the roller 70 is stopped at
a pre-determined place having regard to the amount of collapse
which has been carried out in forming the buckled or collapsing
wall 112, such that the newly formed wall 111 will be of a de-
sired thickness. Generally, the thickness obtained will be some-
what in excess of the sheet metal forming the base 10 (excluding
any strengthening members or hubs) such as about from 1 1/4
to 2 times (preferably 1 1/3 to 1 1/2 times) the thickness of
the base 10. Obviously, if the roller 70 were advanced closer to
the axis a-a, excess metal could squeeze out around the edges of
the roller, leading to a thinner wall 111, but this would not
be desirable, and does not form part of this invention. ~laving
regard to the teachings herein, a person skilled in the art can
easily detérmine the amount of collapse required to give a
suitable thickness 111, as he may re~uire.
If the flanges 18 and 19 have been preformed, as shown
in Figures 4a and 4b, then the faces 72 and 73 will not in them-
selves form flan~es, but will merely mate smoothly against the
pre-existing flanges 18 and 19, preventing metal from escaping
from the area between face 62 and face 71, where the new, thicker
wall 111 is bein~ formed.
A~ter the condition shown in Figure 8b has been reached,
the roller 70 is withdrawn, and the pulley can is removed from `
the chucks 20 and 23. A pulley can having a smooth, robust wall
111 has been formed, which is suitable as a pulley for a flat
belt. The pulley also has flanges 18 and 19, which serve to
retain the belt i~n~y~ce.
.,_
3~
It will be noted that the steps of Figures 7 and 8
each result intrinsically in a pulley having flanges 18 and 19
; Generally, it is preferred to retain these flanges, and one of
~ the advantages of the invention is that the flange reduces the possi-
. - - - -
- 15 - (a)
.. . :,: . .
o ~ ~ ~
35~ ~
t
bility of slippage of v-belts from pulleys formed according to the
invention. However, it is possible, if desired~to remove the
flanges 18 and 19 by means of a roller which nips of the flanges
(as is known in ~he spun pulley art for removing unwanted flanges
or burrs2 or by other conventio~al methods. Therefore, althoush
the flanges form a very desirable part of the invention, it is un-
derstood that unflanged pulleys also can be made by a process
according to the invention.
If desired, instead of removing the pulley as formed
with wall 111 from the chucks 20 and 23, the pulley can instead
be subjected to the application of roller 40, as shown in ~ig. 9.
following the steps shown in Figures 8a and 8b. The roller 40 ap- -
proaches in a manner similar to that described with respect to Fig-
ures 7a and 7b, but, onthis occasion, it engages flat, thick wall
111, rather than the buckled wall 11~. However, the result obtained
is the same as was obtained by the steps described in Figures 7a
and 7b, as can be seen b~y comparing Figure 9 to Figure 7b.
In the foregoing disclosure, the contacting of the various
rollers with the surface of the can wall has been accomplished by
rotating the two chucks 20 and 23 at the same speed and in the
same direction, entraining the can 15 along with them. The roller
~` or rollers which then contact the surface of the can wall (such as,
for example rollex 40 or roller 70) are freely rotatable, but are
not powered. When they contact the can wall they are caused to
rotate by their contact with the rotating can, at the same speed
as the rotating can. It is of course within the scope of the
invention to have the chucks 20 and Z3 freely rotatable, and in-
stead to power the roller which approaches the can wall. Alter-
nately lalthough this is not preferred) both the roller and the
chucks 20 and 23 could be powered so that both the can and the
roller are caused to rotate. The directions of rotation should
preferably be such ~hat, at thP point of contact of the r~ller
- 16 -
.
7~ D . ~, .
3.56 - O
' . ~ ' . . . .
and the can, the two are moving in the same direction. Ho~ver,
they need not be mo~ing at exactly the same speed, and, under
some circumstances/ it is even possible to obtain good results
with the can and the roller moving in differen~ directions, al-
though this is not preferred.
Certain examples of the makin~ of pulleys according to
the disclosure given herein will now be given.
EXAMPLE I
A can of the form shown in Figure 2 is drawn by conven-
tional means from sheet steel of thickness 0.080 inches to have awidth of 6.6 inches and a height h of 2.0 inches. The can is col-
lapsed according to the step shown in Figure 5 to a height hl of 1.0
inch. 1'he method steps with respect to Figure 7a and 7b are then
preformed on the can using a roller 40 having six grooves spaced
- ~.140 inches from one another and having a depth of indentation 42 of
0.140 inches. The roller 40 is moved toward axis a-a until the dis-
tance between wall 62 and the projections 42 is 0.050 inches. When
the roller 40 is removed and the can is removed from the chucks, it
is found to be a well formed grooved pulley having t~o fIanges (18
and 19 in the drawings) of approximately 6.6 inches in diameter and
a central v-belt receiving portion having an avera~e diameter of 6.0
inches and having six grooves corresponding to projections 41. Each
of these grooves is 0-140 inches in depth, and the total depth of
metal measured from the bottom of a vee to the inside of the can
(the distance y in Figure 7b3 is 0.050 inches. The variation of
- depth be~ween the six v-grooves is insignificant, being less than
.002 inches. The dimensions are substantially constant around the
diameter o~ a pulley.
EXAMPLE II
A sheet of sheet steel Q.080 inches in thickness is
~reformed into a can of the,sa~e~sh~pe as t`h,~t descripea in Ex-
~ample I~ The can is collapsed according to the step shown in
Figure S to a height h~ of 1-0 inch. The steps illustrated in
Figures 8a and
- 17 -
~ 3,56~ ~
8b are carried out on the c~n. The roller 70 is allowed to
approach the wall 6n such that the distance between face 71 and
face 62 is 0.120 inches. When the roller 70 is withdrawn, and
the can i5 removed from the chucks 20 and 22 J it is found to have
a v~belt receiving portion 6.0 inches in diameter and two flanges
approximately 6.6 inches in diameter at each side of the v-belt
receiving portion. The thickness of the wall of the v-belt re-
ceiving portion is 0.120 inches, and the pulley is smoothly cylin-
: drical in its v-belt receiving portion.
EXAMPLE III
A pulley formed according to the teachings of Example
II is treated by a subsequent step as illustrated in Figure 9 and the
associated disclosure. The roller 40 is permitted to approach
so that the projections 42 are a distance of 0.050 inches from
the face 62~ When the roller is withdrawn and the can is removed
from the chucks 20 and ~3, a poly v-belt pulley which is indis-
tinguishable from the pulley formed in Example I is formed.
Each of the pulleys formed in Examples I, II and III is
found to be highly resistant to bein~ forced out of round,and is
` 20 judged to be suitable for automotive and indeed heavy truck appli-
` cations.
It is understood that the invention is not limite~ to
` the exact roller structure shown, nor to the exact pulley shapes
iIlustrated, because the particular shapes of the rollers can be
varied to provide other structural embodiments without departing
from the scope of the present invention.
Having now described the features of the invention~ and
the construction and operation of the preferred embodiments of the
novel method and the products provided by them, the inventor
wishes it understood that the protection claimed is not limited
to the exact emhodiments shown, but includes such modifications
thereof as will be obvious to persons skilled in the art, and
I
- 18 -
, . . _ . . , . . . -- . . _ _ _ _ .
35i6 . I
that the protection claimed is therefore limited only as set out
in the appended claims.
___
: 20
- 19- ~
