Note: Descriptions are shown in the official language in which they were submitted.
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PULLEY AND MANUFACTURING METHOD OF THE SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pulley having V-shaped grooves on its outer
circumference and relates to a manllf~chlring method of the same.
2. Description of Relevant Art
As shown in FIG. 1, a pulley which was obtained by working a thin iron plate,
for example, is known. Namely, this pulley is arranged so that a cylindrical bearing
10 section (inner cylindrical section) 1, a web section 2 and a rim section (outer cylindrical
section) 3 are formed by bending an iron plate provided as a material by press, etc., and
that a plurality of V-shaped grooves 4 are formed on the outer circumference of the rim
section 3.
Since the web section 2 is formed by bending the iron plate, one end portions
15 of the bealing section 1 and rim section 3 in the axial direction are cantilevered.
Moreover, the V-shaped grooves 4 are formed on the outer circumference of the rim
section 3 by colllplesshlg the rim section 3 in the axial direction and enlarging its
thickness. Here, the bearing section 1 is arranged so that its inner circumferential
surface is engaged with a bearing 5.
In the conventional pulley, tension of a belt in the V-shaped grooves 4 is
applied to the rim section 3. However, since one end of the rim section 3 in the axial
direction is cantilevered by the web section 2, when the tension is applied thereto from
the belt, strong bending moment is applied to the rim section 3, web section 2 and
bearing section 1. For this reason, there arose problems such that since the whole
25 portion was easily deflected, vibration and noise occurred easily, and durability is
deteriorated. Moreover, since the pulley is forrned by using a thin plate, when the V-
shaped grooves 4 are formed, the thickness of the rim section 3 should be increased.
For this reaxon, there arose a problem such that manufacturing cost was increased due to
the process of increasing the thickness.
SUMMARY OF THE INVENTION
Thle present invention has been achieved with such points in view.
It therefore is an object of the present invention to provide a pulley which is
capable of reducing vibration and noise, improving durability and reducing the
35 manufacturing cost and to provide a manufacturing method thereof.
To achieve the object, a first aspect of the invention provides a pulley
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comprising; an inner cylindrical section, a web section which is extended from a central
portion in an axial direction of the inner cylindrical section, an outer cylindrical section
which is formed at an outer circumferential portion of the web section coaxially with
respect to the inner cylindrical section about the web section, and V-shaped grooves
5 which are formed on an outer circumference of the outer cylindrical section are formed
integrally by cold working.
According to a second aspect of the invention, the web section is formed so
that its thickness becomes thicker gradually with directing towards the inner cylindrical
section and outer cylindrical section.
According to a third aspect of the invention, the inner cylindrical section is
formed with a bearing stopper.
Further, to achieve the object described, a fourth aspect of the invention
provides a manufacturing method of a pulley, comprising the steps of: forming a web
section on a middle portion in a radial direction of a thick ring body by crushing the
middle portion by cold working, forming an inner cylindrical section at an innercircumferential portion of the web section, a central portion of the inner cylindrical
section being the web section, forming a redundant section at the outer circumferential
portion of the web section, a central portion of the redundant section being the web
section, and forming an outer cylindrical section having V-shaped grooves on its outer
circumferential portion, the outer cylindrical section being formed at the outercircumferential portion of the web section coaxially with respect to the inner cylindrical
section about the web section by cold-working V-shaped grooves on an outer
circumference of the redundant section.
According a fifth aspect of the invention, the thick ring body is formed such
that a thick circulate plate body is formed by crushing a cylindrical material by cold
working, that a circular thin section is formed by crushing a central portion of the thick
circular plate body in a circular shape by cold working, and that the circular thin section
is blanked by press.
According to a sixthth aspect of the invention, the thick ring body is formed byblanking a plate shaped material by press.
According to a seventh aspect of the invention, the web section is formed by
crushing a central portion in a radial direction of the thick ring body by cold working so
that its thickness becomes thicker gradually with directing towards the inner cylindrical
section and outer cylindrical section.
In the invention according to the first aspect arranged in the above manner,
since the web section connects the central portion of the inner cylindrical section with
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the central portion of the outer cylindrical portion, even if tension of the belt is applied
to the V-shaped grooves, bending moment generated by the tension is small. Further,
since the tension is applied to the outer cylindrical section symmetrically with respect to
the web section, the bending moment can be prevented from being applied to the web
section and inner cylindrical section. Therefore, the whole portion is extremelydifficult to deflect, so vibration and noise due to the deflection can be reduced, and the
durability can be improved.
According to the second aspect, since the web section is formed so that its
thickness becomes thicker gradually with directing towards the inner cylindrical section
10 and outer cylindrical section, rigidity of a connecting portion between the web section
and inner cylindrical section and a connecting portion between the web section and
outer cylindrical section can be ilnproved, and strength and durability can be improved.
According to the third aspect, the pulley has an integral bearing stopper.
According to the fourth aspect, since a layered structure is obtained by cold
15 working and the strength is increased by hardening due to the cold working, the
durability can be improved. Moreover, since the thickness of the whole portion can be
thin, light-weighting and mini~hlrization can be realized. Further, since the surface
accuracy is improved by the cold working, the fini~hinE step, for example, can be
omitted, and the cost can be reduced.
Furthermore, in the cold working step, since the outer cylindrical section can be
formed so as to have an enough thickness to form V-shaped grooves as a redundantsection, the step of increasing a thickness which is shown in the conventional example is
not required. Therefore, the m~nllf~ctllring steps can be simplified, and the
productivity can be improved and the cost can be reduced.
According to the fifth aspect, since the thick ring body is formed by cold-
working a cylindrical material, yield is improved by cold forging, and material costs can
be reduced, thereby making it possible to reduce the cost.
According to the sixth aspect, since the thick ring body is formed by blanking aplate-shaped material by press, the productivity can be improved, and the cost can be
30 reduced.
According to the seventh aspect, when the web section is cold-worked, a
material positioned in the web section is easy to flow to the inner cylindrical section and
outer cylindrical section. Therefore, a force and time required for the cold working can
be reduced.
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BRIEF DESCRIPTION OF THE DRAWINGS
The above and further objects and novel features of the present invention will
more fully appear from the following detailed description when the same is read in
conjunction with the accompanying drawings, in which:
FIG. 1 is a sectional view showing a pulley as a conventional example;
FIG. 2 is a sectional view showing a pulley according to the first embodiment
of the present invention;
FIG. 3 is a drawing showing a manufacturing method of the pulley, i.e., a side
view showing a cylindrical material;
FIG. 4 is a drawing showing the manufacturing method of the pulley, i.e., a
side view showing a thick circular plate;
FIG. 5 is a drawing showing the m~nu~ctllring method of the pulley, i.e., a
sectional view showing a state that a thick circular portion is formed on the thick
circular plate;
FIG. 6 is a drawing showing the manufacturing method of the pulley, i.e., a
sectional view showing a thick ring body;
FIG. 7 is a drawing showing the manufacturing method of the pulley, i.e., a
sectional view showing a rough shaped section of the pulley;
FIG. 8 is a drawing showing a forming unit of the pulley, i.e., a sectional view20 showing a unit for forming the rough shaped section of the pulley;
FIG. 9 is a drawing showing a forming unit of the pulley, i.e., a sectional viewshowing a unit for forming a rim section and V-shaped grooves;
FIG. 10 is a sectional view of the pulley according to the second embodiment
of the present invention;
FIG. 11 is a drawing showing a forming unit of the pulley, i.e., a sectional view
showing a unit for forming the rough shaped section of the pulley;
FIG. 12 is a drawing showing a forming unit of the pulley, i.e., a sectional view
showing a unit for forming the rim section and V-shaped grooves;
FIG. 13 is a sectional view showing the rough shape section of the pulley
30 according to the third embodiment of the present invention;
FIG. 14 is a sectional view showing the finished pulley;
FIG. 15 is a drawing showing a forming unit of the pulley, i.e., a sectional view
showing a unit for forrning the rough shaped section of the pulley;
FIG. 16 is a drawing showing a forming unit of the pulley, i.e., a sectional view
35 showing a unit for forming the rim section and V-shaped grooves;
FIG. 17 is a perspective view showing a plate-shaped material used in the
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fourth embodiment of the present invention; and
FIG. 18 is a drawing showing the manufacturing method of the pulley, i.e., a
perspective view showing a thick ring body.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
There will be detailed below the preferred embodiments of the present invention
with reference to FIGs. 2 through 16. Here, FIGs. 2 through 9 show the first
embodiment, FIGs. 10 through 12 show the second embodiment, FIGs. 13 through 16
10 show the third embodiment, and FIGs. 17 and 18 show the fourth embodiment.
First, the description will be given as to the first embodiment of the present
invention on reference to FIGs. 2 through 9. Namely, a pulley 10 in the first
embodiment, as shown in FIG. 2, is obtained by forming a bearing section (inner
cylindrical section) 11 formed in a cylindrical shape, a web section 12 which is extended
16 from a central portion of the bearing section 11 in the axial direction to the outside
radially, a cylindrical rim section (outer cylindrical section) 13 which is formed at the
outer circumferential portion of the web section 12 coaxially with respect to the bearing
section 11 about the web section 12, and V-shaped grooves 14 which are formed on the
outer circumference of the rim section 13. The bearing section 11, web section 12, rim
20 section 13 and V-shaped grooves 14 are formed integrally by cold working.
A plurality of the V-shaped grooves 14 are so-called poly-V-shaped grooves.
The respective V-shaped grooves 14 are formed symmetrically with respect to the web
section 12. Moreover, the inner circumferential surface of the bearing section 11 is
engaged with a bearing (not shown) similarly to the conventional example.
Next, the description will be given as to the manufacturing method of the
aforementioned pulley 10 on reference to FIGs. 3 through 9. First, a cylindrical iron
material W1 shown in FIG. 3 is cold-forged (cold-worked) by press so that a thick
circular plate W2 shown in FIG. 4 is formed. Then, as shown in FIG. 5, a centralportion of the thick circular plate W2 is crushed in a circular shape from the top and
30 bottom surfaces by the cold forging using press, and a circular thin section W2a is
formed. As shown in FIG. 6, the circular thin section W2 is blanked by press so that a
thick ring body W3 is formed.
Thereafter, as shown in FIG. 7, a middle portion of the thick ring body W3 in a
radial direction is crushed from the top and bottom surfaces by the cold forging using
35 press so that the bearing section 11 is formed on the inner circumference of the thick
ring body W3, the web section 12 is formed on the middle portion and a redundant
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section W4a used for forming the rim section 13 is formed on the outer circumference.
Namely, a rough shaped section W4 of the pulley is formed. As shown in FIG. 8, the
rough shaped section W4 is cold-forged by a bottom die M1, top die M2, inner
circumference holding die M3 and outer circumference holding die M4.
6 Next, as shown in FIG. 9, while the bearing section 11 and web section 12 are
being held by a lower surface holding die M5, upper surface holding die M6 and inner
circumference holding die M7, the rim section 13 and V-shaped grooves 14 are rolled
from the outer circumferential surface and cold-formed by using a roller die M8. As a
result, the pulley 10 is finished.
In the pulley 10 arranged in the above manner, since the web section 12
connects the central portion of the bearing section 11 to the central portion of the rim
section 13, the tension of the belt is applied to the V-shaped grooves 14. As a result,
even if bending moment is generated, the bending moment is weak. Furthermore,
since the V-shaped grooves 14 are provided symmetrically with respect to the web15 section 12, the bending moment is balanced at the rim section 13. For this reason, the
bending moment can be prevented from being applied to the web section 12 and bearing
section 11. Therefore, the whole portion is difficult to deflect, and thus vibration and
noise can be reduced, and durability of a bearing can be improved. Further, in this
pulley 10, since a width between the bearing section 11 and the rim section 13 with
20 which a bearing is engaged, i.e., a width of the web section 12 can be narrowed, an outer
diameter of the rim section 13 can be small, and thus the pulley which is specially
suitable to a pulley with small diameter can be obtained.
In addition, since a layered structure is obtained by a series of cold working and
strength is increased due to hardening by the cold forging, the durability can be further
25 improved, and thus the thickness of the whole structure can be small. Therefore, the
cost can be reduced. Further, since surface accuracy is improved by the cold forging,
steps for fini~hinE the inner surface of the bearing section 11 and the V-shaped grooves
14, for example, can be omitted, and this can also reduce the cost. Namely, the
productivity can be improved.
Furthermore, in the cold forging step, since the rim section 13 can be formed soas to have an enough thickness to form the V-shaped groove 14 as the redundant section
W4a, the step of increasing a thickness in the conventional example is not required.
Therefore, the cost can be reduced. Moreover, since the yield is improved by the cold
forging, the material costs can be reduced.
Next, the description will be given as to the second embodiment of the present
invention on reference to FIGs. 10 through 12. However, the same reference numerals
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are given to the components which are common to the aforementioned first embodiment,
and the description thereof is simplified. A point of the second embodiment different
from the first embodiment is that a stopper 11a for a bearing is formed integrally with
the bearing section 11.
Namely, as shown in FIG. 10, an annular stopper 11a which is bent from one
end in its axial direction towards the inner side is formed at the bearing section 11. As
shown in FIG. 11, the stopper 11a is formed by cold forging at the step of forming the
rough shaped section W4 of the pulley. Moreover, as shown in FIG. 12, the rim
section 13 and V-shaped grooves 14 are formed by the roller die M8 with the bearing
10 section 11 including the stopper 11a and the web section 12 being held by the dies MS,
M6 and M7.
In the pulley 10 structured in the above manner, since the rough shaped section
W4 of the pulley can be formed by the cold forging and at the same time the inner
surface of the bearing section 11 and the stopper 11a can be formed accurately, a
15 bearing is engaged directly with the bearing section 11, and the bearing can be
positioned. Therefore, the productivity can be improved.
Next, the description will be given as to the third embodiment of the present
invention on reference to FIGs. 13 through 16. However, the same reference numerals
are given to the components which are common to the aforementioned first embodiment,
20 and the description thereof is simplified. A point of the third embodiment which is
different from the first embodiment is that the thickness of the web section 12 becomes
thicker gradually with directing towards the bearing section 11 and the rim section 13.
Namely, as shown in FIGs. 13 and 14, the web section 12 is formed so that its
thickness becomes thicker gradually with directing towards the bearing section 11 and
25 rim section 13 on a circularly arced surface.
The web section 12 formed in such a manner, as shown in FIG. 15, is formed
by cold forging at the step of forming the rough shaped section W4 of the pulley.
When the web section 12is cold-forged, the material positioned in the web section 12is
easy to flow to the sides of the bearing section 11 and rim section 13. Moreover, as
30 shown in FIG. 16, the rim section 13 and V-shaped grooves 14 are formed by the roller
die M8 with the bearing section 11 and web section 12 being held by the dies M5, M6
and M7.
In the pulley 10 structured in the above manner, since the web section 12 is
formed so that its thickness becomes thicker gradually with directing towards the
35 bearing section 11 and rim section 13 on a circularly arced surface, when the web
section 12is cold-forged, the material positioned in the web section 12is easy to flow
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towards the bearing section 11 and rim section 13. Therefore, a force and time
required for cold forging can be reduced. Moreover, since the thickness of a portion
requiring strength can be increased easily and the thickness of a portion which does not
require strength can be reduced easily, the strength and light-weighting of the pulley 10
5 can be improved.
In the aforementioned embodiments, a plurality of the V-shaped grooves 14 are
provided, but only one V-shaped groove 14, namely, a so-called mono-V-shaped groove
may be provided. However, it is preferable that the mono-V-shaped groove is formed
symmetrically with respect to the web section 12. Further, the V-shaped grooves 14
10 may be arranged by combining the mono-V-shaped groove and poly-V-shaped groove.
Namely, both the mono-V-shaped groove and poly-V-shaped groove may be provided to
the rim section 13.
In addition, also in the third embodiment, a stopper for a bearing may be
provided.
Next, the description will be given as to the fourth embodiment of the present
invention on reference to FIGs. 17 and 18. However, the same reference numerals are
given to the components which are common to the first embodiment, and the description
thereof is omitted. A point of the fourth embodiment different from the first
embodiment is that the thick ring body W3 is formed by pressing a plate-shaped
20 material W0.
As shown in FIG. 18, the ring-shaped thick ring body W2 is formed by
blanking the thick plate-shaped material W0 by press. When a middle portion in the
radial direction of the thick ring body W2 is crushed in the similar manner to the first
embodiment, the rough shaped section W4 of the pulley is formed. Since the forming
25 structure hereafter is the same as that in the first embodiment, the description thereof is
omitted.
According to the fourth embodiment, since the thick ring body W2 can be
formed by blanking the plate-shaped material W0 by press, the thick ring body W2 can
be formed only by press. As a result, the manufacturing steps can be simplified, the
30 productivity can be improved, and thus the cost can be reduced.
Here, the thick circular plate body W2 obtained when the thick ring body is
formed may be broken as scrap, but similarly to the thick circulate plate body W2 shown
in the first embodiment, after the central portion of the thick circulate plate body W2 is
crushed from the top and bottom surfaces in a circulate shape by cold forging using
35 press and a circular thin section W2a is formed, the thick ring body W3 is formed by
blanking the circular thin section W2a using press so as to be used. As a result, the
CA 0222~772 1997-12-22
material can be used effectively, and thus the cost can be reduced.
While preferred embodiments of the present invention have been described
using specific terms, such description is for illustrative purposes, and it is to be
understood that changes and variations may be made without departing from the spirit or
5 scope of the following daims.
