U.S. patent application number 09/756781 was filed with the patent office on 2001-05-17 for method of manufacturing a speed gear and an apparatus for manufacturing a speed gear.
Invention is credited to Hasegawa, Heiichi.
Application Number | 20010001165 09/756781 |
Document ID | / |
Family ID | 18490488 |
Filed Date | 2001-05-17 |
United States Patent
Application |
20010001165 |
Kind Code |
A1 |
Hasegawa, Heiichi |
May 17, 2001 |
Method of manufacturing a speed gear and an apparatus for
manufacturing a speed gear
Abstract
Speed gear are manufactured by integrally molding, by either hot
or warm forging, a speed gear section and a clutch spline section.
Teeth of the speed gear in the speed gear section and an involute
spline parallel to an axial line of the gear in the clutch spline
section are rough formed. The involute spline parallel to the axial
line of gear formed on the section of clutch spline is formed, by
cold forging, into an involute spline with a back taper having a
chamfer at the tip. The teeth of the speed gear formed at the speed
gear section are finish formed by forming the speed gear teeth by
rolling dies, by cold forging, while turning them around a shaft
hole with reference to the clutch spline section forming the
involute spline with back taper. A speed gear having a speed gear
section and a clutch spline section including speed gear teeth and
an involute spline with a back taper having a chamfer at the tip is
thereby provided.
Inventors: |
Hasegawa, Heiichi; (Hikone,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W. SUITE 800
WASHINGTON
DC
20006
US
|
Family ID: |
18490488 |
Appl. No.: |
09/756781 |
Filed: |
January 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09756781 |
Jan 10, 2001 |
|
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|
09468089 |
Dec 21, 1999 |
|
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Current U.S.
Class: |
29/34R ;
29/893.3 |
Current CPC
Class: |
B23P 15/14 20130101;
F16H 55/171 20130101; Y10T 29/49467 20150115; Y10T 29/49474
20150115; B21K 1/30 20130101; Y10T 29/5116 20150115; B21H 5/02
20130101; Y10T 29/49471 20150115; F16H 55/17 20130101 |
Class at
Publication: |
29/34.00R ;
29/893.3 |
International
Class: |
B23P 015/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 1997 |
JP |
9-367901 |
Claims
What is claimed is:
1. A manufacturing apparatus of speed gear, comprising a chucking
means for holding the shaft hole pierced at the center of the work
gear, a tail stock for turning said work gear, through the chucking
means, around its shaft hole, a synchronizing gear disposed in the
tail stock that turns together with the tail stock, a driven gear
engaging with said synchronizing gear, and a rolling spindle on
which are disposed rolling dies, characterized in that said work
gear is submitted to finish the forming of teeth of speed gear
rough-formed in advance on the section of speed gear of said work
gear, by means of said rolling dies turning in synchronization with
said work gear, while turning said work gear around its shaft hole,
through said synchronizing and driven gears.
2. A manufacturing apparatus of speed gear as defined in claim 1,
wherein said chucking means is comprised of a collet chuck and a
male cone to be inserted in the collet chuck, so as to expand the
diameter of the collet chuck and hold the shaft hole pierced at the
center of the work gear.
3. A manufacturing apparatus of speed gear as defined in claim 1,
wherein said rolling dies are constructed in a way to perform
finish forming of helical teeth rough-formed in advance at the
section of speed gear of the work gear.
4. A manufacturing apparatus of speed gear as defined in claim 1,
wherein said rolling dies are constructed in a way to also perform
crowning at the tooth flank of the teeth of speed gear rough-formed
in advance at the section of speed gear of the work gear.
Description
1. This is a Divisional Application of U.S. patent application Ser.
No. 09/468,089 filed Dec. 21, 1999 which in turn is a Divisional
Application of U.S. patent application Ser. No. 09/058,846 filed
Apr. 13, 1998.
BACKGROUND OF THE INVENTION
2. The present invention relates to a speed gear having a speed
gear section and a clutch spline section mainly used for a
transmission gearbox, and a manufacturing method and apparatus for
the speed gear.
3. Conventionally, a speed gear having a speed gear section and a
clutch spline section used for a transmission gearbox is
manufactured by methods such as:
4. 1. A method which comprises forming a speed gear section and
spline teeth respectively by submitting a speed gear section and a
clutch spline section, integrally molded by hot forging, to
machining such as hobbing, etc;
5. 2. A method which comprises forming a speed gear section by
submitting a speed gear section molded by hot forging to machining
such as hobbing, etc., and integrating the speed gear section and a
clutch spline section having spline teeth molded by cold forging by
either spline connection or electron beam welding; and
6. 3. A method which comprises forming a speed gear section by
submitting a speed gear section and a clutch spline section
integrally molded by hot forging to machining such as hobbing, etc.
and forming a clutch spline section by hot forging and cold
forging, respectively.
7. By the way, methods 1 to 3 all consist in forming the speed gear
section by submitting the speed gear section to machining such as
hobbing, etc. For that reason, they had a problem in that the metal
flow of the section of speed gear was cut off, not only reducing
the strength of the gear but also inevitably leading to an increase
of the manufacturing cost due to machining.
8. As a solution to this problem, adoption of a method for forming
speed gear teeth in the speed gear section by cold forging with a
press may be conceivable, but no high-accuracy speed gear section
could be manufactured because of the difficulty of securing
concentricity between the clutch spline section and the speed gear
section forming speed gear teeth.
9. Moreover, a speed gear W generally used for the transmission
gearbox at present is provided, as shown in FIG. 11, with speed
gear section Pa and clutch spline section Pb, forming helical teeth
Ga as speed gear teeth at the speed gear section Pa and an involute
spline with a back taper Gb having a chamfer Cb at the tip of the
clutch spline section Pb, respectively.
10. The helical teeth Ga formed at the speed gear section Pa
generally have, as shown in FIG. 10 (C), a torsional angle .alpha.
of 15.degree. to 35.degree. on the right or on the left, and are
formed as high teeth to reduce the gear noise produced during
high-speed rotation of the speed gear W.
11. For that reason, in the case where an attempt is made to form
helical teeth Ga by cold forging with a press, for example, the
greater part of the forming pressure must be supported by the tooth
flank Fa of the helical teeth Ga. This causes deflection of the
helical teeth Ga, producing a gap in the tooth flank Fb and
inducing the material to flow into that gap.
12. As a result, the helical teeth Ga are formed differently at the
torsional angle a of the tooth flank Fa and the torsional angle
.alpha. b of the tooth flank Fb, making it difficult to manufacture
a speed gear of high accuracy. In addition, since this trend
becomes particularly conspicuous as the torsional angle .alpha.
gets larger, it was impossible to form helical teeth Ga with a
torsional angle .alpha. of 30.degree. or more by cold forging with
a press.
13. Furthermore, as the speed gear W, a type forming helical teeth
Ga having crowning Ca on the tooth flank (see FIG. 10 (D)) at the
speed gear section Pa was also adopted. But this crowning could not
be formed by cold forging with a press.
SUMMARY OF THE INVENTION
14. In view of the problems inherent in conventional speed gears
and their manufacturing methods, the object of the present
invention is to provide a speed gear having a speed gear section
and a clutch spline section including speed gear teeth and an
involute spline with a back taper having a chamfer at the tip, and
a manufacturing method and apparatus for the speed gear
15. To achieve the objective, the speed gear according to the
present invention has a speed gear section and a clutch spline
section integrally formed by forging. The clutch spline section is
provided with an involute spline with a back taper having a chamfer
at the tip. Speed gear teeth are formed by forging with rolling
dies at the speed gear section with reference to the clutch spline
section forming the involute spline with a back taper.
16. The speed gear forming the subject of the present invention
includes a speed gear having helical teeth or flat teeth as the
teeth of the speed gear.
17. Moreover, the speed gear forming the subject of the present
invention also includes a speed gear having crowning on the tooth
flank.
18. Furthermore, the speed gear forming the subject of the present
invention further includes a speed gear in which the tip diameter
of the back tapered involute spline formed on the clutch spline
section is larger than the root diameter of the speed gear teeth
formed on the speed gear section and the clearance between the
speed gear section and the clutch spline section is no more than 2
mm.
19. Further, the speed gear forming the subject of the present
invention includes a speed gear in which an involute spline with a
back taper is formed in a shape conformable to the tip shape of
dies by pushing in the dies, radially disposed against the axial
line of the gear among spline teeth parallel to the axial line of
the gear formed by forging, toward the center of gear in a
direction perpendicular to the axial line of the gear.
20. The manufacturing method of the speed gear according to the
present invention comprises integral molding, by either hot or warm
forging, the speed gear section and the clutch spline section,
rough-forming speed gear teeth in the speed gear section and
involute splines parallel to the axial line of the gear in the
clutch spline section, forming the involute splines parallel to the
axial line of the gear formed on the clutch spline section by cold
forging into an involute spline with a back taper having a chamfer
at the tip, and then finish forming the speed gear teeth formed at
the speed gear section. The finish forming of the speed gear teeth
is done by forming the speed gear teeth by rolling dies, by cold
forging, while turning them around a shaft hole located with
reference to the clutch spline section forming the involute spline
with a back taper.
21. In this case, the manufacturing method may be constructed in a
way to form crowning on the tooth flank of the speed gear teeth by
means of rolling dies.
22. Moreover, the forming of an involute spline with a back taper
may be performed by pushing in dies, radially disposed against the
axial line of the gear among spline teeth parallel to the axial
line of the gear formed at the clutch spline section, toward the
center of the gear in the direction perpendicular to the axial line
of the gear, in a shape conformable to the tip shape of the
dies.
23. The manufacturing apparatus of the speed gear according to the
present invention, relating to the method of the present invention,
comprises a chuck for holding the shaft hole at the center of the
work gear, a tail stock for turning the work gear through the chuck
around its shaft hole, a synchronizing gear disposed in the tail
stock that turns together with the tail stock, a driven gear
engaging with the synchronizing gear, and a rolling spindle on
which are disclosed rolling dies. The work gear is submitted to
finish forming of the rough-formed speed gear teeth by the rolling
dies turning in synchronization with the work gear while turning
the work gear around its shaft hole through the synchronizing gear
and the driven gear.
24. In this case, the chuck may comprise a collet chuck and a male
cone to be inserted in the collet chuck so as to expand the
diameter of the collet chuck and hold the shaft hole at the center
of the work gear.
25. Moreover, the rolling dies may be constructed to perform finish
forming of helical rough-formed teeth.
26. Furthermore, the rolling dies may be constructed to also
perform crowning at the tooth flank of the rough-formed speed gear
teeth.
27. According to the present invention, it becomes possible to
integrally form, by forging, the speed gear section and the clutch
spline section including speed gear teeth and an involute spline
with a back taper having a chamfer at the tip, thus providing the
following actions and effects.
28. 1. By forming speed change gear teeth and an involute spline
with a back taper having a chamfer at the tip by forging, it
becomes possible to improve the strength of the gear without
cutting the metal flow of the teeth, avoiding an increase in
manufacturing cost due to machining, and reducing the manufacturing
cost of the speed gear.
29. 2. It is easy to concentrically secure the clutch spline
section forming an involute spline with a back taper with the speed
gear section forming speed gear teeth, enabling the manufacture of
a highly-accurate speed gear.
30. 3. When forming helical teeth as speed gear teeth, it is
possible to manufacture a highly-accurate speed gear, especially
helical teeth with a torsional angle of 30.degree. or more, by
forging.
31. 4. When forming speed gear teeth by forging, it is possible to
also perform crowning at the tooth flank of the speed gear teeth at
the same time.
32. 5. By forming an involute spline with a back taper having a
chamfer at the tip by forging, it becomes possible to not only
manufacture a highly-accurate speed gear without hooking due to
machining, but to also obtain a speed gear with excellent shift
feeling.
33. 6. The absence of restrictions on the component materials of
the speed gear enables the use of high-strength, difficult to cut
steel, making it possible to manufacture a compact speed gear
easily.
34. 7. It is possible to manufacture a speed gear with a shape
difficult to achieve through machining, and obtain a compact speed
gear.
BRIEF DESCRIPTION OF THE DRAWINGS
35. FIG. 1 is an explanatory drawing showing a manufacturing
process of a speed gear according to the present invention.
36. FIG. 2 is a front sectional view of an apparatus for
rough-forming a gear used in the manufacture of the speed gear
according to the present invention.
37. FIG. 3 is a front sectional view of an apparatus for forming an
involute shape used in the manufacture of the speed gear according
to the present invention.
38. FIGS. 4 (A) and 4 (B) show a lower die of the apparatus for
forming an involute shape, 4 (A) being a plan view, and 4 (B) a
front elevation of a main part.
39. FIGS. 5 show dies of the apparatus for forming an involute
shape, 5 (A) being a plan view, 5 (B) a partially broken front
elevation, and 5 (C) an explanatory drawing of a die tip.
40. FIG. 6 is a front sectional view of a flow forming apparatus
used for the manufacture of the speed gear according to the present
invention.
41. FIG. 7 is an expanded view of a main part of the flow forming
apparatus.
42. FIG. 8 is an explanatory drawing showing the relation between a
synchronizing gear and a driven gear.
43. FIG. 9 is an explanatory drawing showing the relation between
rolling dies and an intermediate product.
44. FIGS. 10 (A)-10 (D) are explanatory drawings of various kinds
of speed gears.
45. FIGS. 11 (A)-11(C) show a typical speed gear, 11 (A) being a
sectional view, 11 (B) an exploded view of a main part, and 11 (C)
an expanded explanatory drawing of teeth of the speed gear.
DETAILED DESCRIPTION OF THE INVENTION
46. Explanation will be given hereafter of an embodiment of a speed
gear, a manufacturing method and an apparatus according to the
present invention, based on the drawings.
47. First, a method for forming the speed gear of the present
invention will be explained by using FIG. 1, which concerns a case
of forming of a speed gear W of a shape as indicated in FIGS. 11
(A) and 11 (B).
48. First, a raw material suitable for the speed gear W to be
manufactured is cut to a prescribed length by means of a billet
shear or a saw (FIG. 1 (1), (2)). This raw material W0 is heated to
a temperature suitable for either hot or warm forging (FIG. 1
(3)).
49. In this case, materials suitable for the speed gear W, such as
SC steel, SCM steel, SNC steel, SNCM steel, SCR steel, etc., may be
used as the raw material.
50. Moreover, the heating temperature may be set depending on the
type of forging (hot or warm), the nature of the material, the
shape, size, etc., at 1150.degree. C. to 1200.degree. C., for
example.
51. After heating, the raw material W0 is submitted to a plural
number of processes to integrally form a speed gear section Pa and
a clutch spline section Pb and to form an intermediate product W4
having rough-formed speed gear teeth Ra at the speed gear section
Pa and rough-formed involute spline Rb at the clutch spline section
Pb parallel to the axial line of the gear.
52. This hot forging process is usually composed, though not
particularly restricted to such composition, of four processes,
i.e. an upsetting process (FIG. 1 (4)), a blocker process (FIG. 1
(5)), a finisher process (FIG. 1 (6)) and a piercing process (FIG.
1 (7)).
53. Among those processes, the upsetting process (FIG. 1 (4)) is a
process for forming the raw material W0 into a shape easy for
forging. The material W1 which has passed through this process is
submitted to the blocker process (FIG. 1 (5)) and the finisher
process (FIG. 1 (6), to be described in detail later) to be
adjusted into the required general shape and to have the required
teeth rough-formed on the speed gear section Pa and the clutch
spline section Pb.
54. The blocker process (FIG. 1 (5)) and the finisher process (FIG.
1 (6)) may be further composed of a plural number of processes,
depending on the nature of the material W1, the shape and size of
the intermediate product W1 to be formed, etc.
55. The intermediate product W4 realized by forming a shaft hole H
at the center of the intermediate product W3 is obtained with the
piercing process (FIG. 1 (7)). The diameter of the shaft hole H is
formed to be slightly smaller than the final finished
dimension.
56. The intermediate product W4, having the required teeth
rough-formed on the speed gear section Pa and the clutch spline
section Pb, are submitted, in a heat treating process (FIG. 1 (8)),
to heat treatment such as annealing, etc. In a shot blasting
process (FIG. 1 (9)), scale adhering to the surface of the
intermediate product W4 is removed. In a lubrication process (FIG.
1 (10)), required lubrication such as a bonderite process,
treatment by a molybdenum disulfide based lubricant, etc. will be
performed to ensure smooth execution of the subsequent cold forging
process.
57. The intermediate product W4 which has passed through the
lubrication process (FIG. 1 (10)) will be submitted, in a cold
coining process (FIG. 1 (1 1)), to finish forming of involute
spline Rb. Then, in an involute spline forming process (FIG. 1
(12), to be described in detail later), an involute spline Sb,
parallel to the axial line of the gear and formed at the clutch
spline section Pb, will be formed from the involute spline Rb in a
back tapered shape.
58. The intermediate product W6 which passed through the involute
spline forming process (FIG. 1 (12)) will be submitted, in a
machining process (FIG. 1 (13)), to lathe turning of the end face
of the intermediate product W6, the inner circumferential surface
of the shaft hole H and other parts, with reference to the clutch
spline section Pb having involute splines with back taper Gb formed
with final finished dimensions.
59. The intermediate product W7 which passed through the machining
process (FIG. 1 (13)) will be passed on to a speed gear teeth
forming process (FIG. 1 (14), to be described in detail later),
where the speed gear teeth Ra formed at the speed gear section Pa
are finish formed into speed gear teeth while turning around the
shaft hole H.
60. At that time, crowing Ca may be formed on the tooth flank of
the speed gear teeth Ra.
61. The intermediate product W8 which passed through the speed gear
teeth forming process (FIG. 1 (14)) will be submitted, in the
machining process (FIG. 1 (15)), to lathe turning of the outer
circumference, end face and other parts of the speed gear section
Pa. Then, in a heat treating process (FIG. 1 (16)), required heat
treatments such as carbo-hardening, tempering, etc. are carried
out. By further passing the intermediate product W8 through the
grinding process (FIG. 1 (17)), speed gear W as a final product
results.
62. Next, the finisher process (FIG. 1 (6)) will be described in
detail.
63. The finisher process consists in integrally forming the speed
gear section Pa and the involute spline with back taper Pb on the
intermediate product W2, provided in the required general shape by
the blocker process (FIG. 1 (5)) of either a hot or warm forging
process, rough-forming speed gear teeth Ra at the speed gear
section Pa and rough forming involute spline Rb parallel to the
axial line of the gear at the involute spline with back taper.
64. FIG. 2 indicates an example of an apparatus for rough-forming
gear used for executing this finisher process.
65. This apparatus for rough-forming gear is designed to
simultaneously rough-form helical teeth Ra as speed gear teeth at
the speed gear section Pa and involute spline Rb parallel to the
axial line of the gear at the clutch spline section Pb. Its
structure will be explained hereafter.
66. A die mounting stand 31 is attached on a base 30, and a die 32
for forming gear is mounted on this die mounting stand 31.
67. The die 32, formed in a cylindrical shape, is provided, at its
inner circumferential surface, with forming teeth 32a corresponding
to the helical teeth Ra to be formed at the speed gear section Pa
of the intermediate product W2.
68. Moreover, in the die 32 will be inserted, from above and below
respectively, an upper punch 33 U and a lower punch 33 D, which
produce plastic deformation by holding and pressing the
intermediate product W2 from above and below. In this case, the die
32 will be constructed in such a way that, as the forming teeth 32a
of the die 32 and driven teeth 33a formed at the outer
circumference of the lower punch 33D engage with each other and the
lower punch 33D moves in the die 32, the lower punch 33D turns
according to that amount of movement.
69. The upper and lower punches 33U, 33D are formed in a shape
capable of forming the intermediate product W2 into the
intermediate product W3 by producing plastic deformation in the
intermediate product W2 in collaboration with the die 32. The lower
punch 33D is further provided, at its inner circumferential surface
at the top, with forming teeth 33b corresponding to the involute
spline Rb parallel to the axial line of the gear to be formed at
the clutch spline section Pa of the intermediate product W2.
70. The upper and lower punches 33U, 33D are rotatably supported
through upper and lower bearing plates 34U, 34D. The upper punch
33U is made to go up and down by means of a lifter 38 through upper
punch mounting base 37 while the lower punch 33D is made to go up
and down by means of a piston 36 moving as hydraulic operating
fluid is fed into a hydraulic cylinder 35.
71. The lower punch 33D, in which a lower knockout pin P1 is
inserted, is operated by a knockout pin P2 passing through the base
30, while the upper punch 33U, in which upper knockout pin P3 is
inserted, is operated by knockout pin P4 passing through the lifter
38.
72. Next, explanation will be given of the motions of this
apparatus for rough-forming gear.
73. The intermediate product W2 is placed on the lower punch 33D
and, as the lifter 38 is made to come down, the intermediate
product W2 is held and pressed between the upper punch 33U and the
lower punch 33D to produce plastic deformation, and rough-form
helical teeth Rb at the speed gear section Pa and involute spline
Rb parallel to the axial line of the gear at the clutch spline
section Pb at one time.
74. After that, hydraulic operating fluid is supplied into the
hydraulic cylinder 35 to make the piston 36 go up and push up the
lower punch 33D. In this case, the piston 36 is made to go up until
the formed intermediate product W3 is detached from the gear die
32.
75. At that time, as the lower punch 33D moves in the gear die 32,
the lower punch 33D turns in proportion to the amount of that
movement, and the formed intermediate product W3 also turns at the
same time, because the forming teeth 32a of the gear die 32 are
engaged with the driven teeth 33a formed on the outer
circumferential surface of the lower punch 33D. This makes it
possible to take out the intermediate product W3 without causing
damage to the helical teeth Ra and the involute spline Rb parallel
to the axial line of the gear formed respectively at the speed gear
section Pa and the clutch spline section Pb of the intermediate
product W3.
76. To take out the intermediate product W3, the lifter 38 is made
to up to release the holding of the intermediate product W3 by the
upper punch 33U and the lower punch 33D. Then the piston 36 of the
hydraulic cylinder 35 is made to go up to detach the helical teeth
Ra formed at the section of speed gear Pa of the intermediate
product W3 from the forming teeth 32a of the gear die 32. After
that, the lower knockout pin P1 is made to protrude by the knockout
pin P2, and the upper knockout pin P3 is made to protrude by the
knockout pin P4, to detach the involute spline Rb from the forming
teeth 33b of the lower punch 33D and release the intermediate
product W3 from the upper and lower punches 33U, 33D.
77. Next, the involute spline forming process of FIG. 1 (12) will
be explained in detail.
78. The involute spline forming process consists in performing, in
the cold coining process (FIG. 1 (11)), finish forming of the
involute spline Rb parallel to the axial line of the gear
rough-formed at the clutch spline section Pb, and then forming, on
intermediate product W5, the involute spline parallel to the axial
line of the gear formed at the clutch spline section Pb into the
involute spline with back taper Gb.
79. FIG. 3 to FIG. 5 indicate an example of an apparatus for
forming the involute spline used for this forming process.
80. An apparatus for forming an involute spline 1, designed to form
an involute spline parallel to the axial line of the gear formed at
the clutch spline section Pb into an involute spline with back
taper Gb, is constructed as explained hereafter.
81. An upper die 11 is disposed on an upper die mounting base 12 so
as to be urged downwardly by a spring 12A.
82. A lower die 13 opposed to the upper die 11 is fixed on a lower
die mounting base 14. A punch 15 is disposed on the lower die
mounting base 14 through the lower die 13. Outside the punch 15 is
disposed a knockout cylinder 16 of a cylindrical shape and operated
with a knockout pin 20. A cylindrical case 17 is fixed to the lower
die mounting base 14. On the case 17 are formed, at a prescribed
pitch, cam inserting holes 17H agreeing with the angle between
teeth and the number of teeth of the involute spline Gb for forming
the involute spline Sb into the involute spline with back taper Gb.
The outer side faces of these cam inserting holes 17H are formed
into cam supporting faces 17F. Cams 21 are inserted in the cam
inserting holes 17H, respectively.
83. The cams 21 inserted in cam inserting holes 17H are supported
on the lower die mounting base 14 through a spring 24, being
supported by a circular flange 18 operated by a knockout pin 19,
and fixed to this circular flange 18 by means of a bolt 21V.
84. The length of a knockout pin 19 and the knockout pin 20 are set
in such a way that the knockout pin 20 pushes up the knockout
cylinder 16 after the knockout pin 19 has pushed up the flange
18.
85. The cam 21, the back face of which is finished with high
accuracy to be in sliding contact with the cam supporting face 17F
of the case 17, has a pin 22 on the inner side at its lower part
projecting such that a top end of the pin 22 inclines inwardly. A
die pressing face 21T has a tilt angle equal to the inclination of
the pin 22 and is formed on the inner side face, facing the pin
22.
86. At the top of the lower die 13 are formed, as shown in FIG. 4,
die inserting holes 13H agreeing with the angle between teeth and
the number of teeth of the involute spline with back taper Gb,
toward the center of the lower die 13.
87. The die inserting holes 13H have sections that are about
circular and tops cut in a plane. In these die inserting holes 13H
are inserted dies 23 having sections that are about circular and
having tops cut in a plane. This enables a construction in which
the dies 23 are radially disposed toward the center of the lower
die 13 while the case 17 supports the flat part of the dies 23 to
prevent turning of the dies 23.
88. A tip 23D of the die 23 is pressed against the involute spline
Sb parallel to the axial line of the gear formed at the clutch
spline section Pb, producing plastic deformation, and thus changing
the shape into a shape available for formation into the involute
spline with back taper. Moreover, in the die 23 is drilled a pin
inserting hole 23H for inserting the pin 22. The rear end face 23T
of the die 23 is formed into an inclined face corresponding to the
die pressing face 21T of the cam 21.
89. Next, explanation will be given on the motions of this
apparatus 1 for forming the involute spline.
90. The intermediate product W5 is placed on the lower die 13. As
the upper die mounting base 12 is made to come down, the
intermediate product W5 is held between the upper die 11 urged by
the spring 12S and the lower die 13. The top face of the cam 21 is
pressed by the upper die mounting base 12, with a slight delay
after the holding of the intermediate product W5.
91. As a result, the cam 21 and the flange 18 are pushed down, and
the rear end face 23T of the die 23 is pressed by the die pressing
face 21 T of the cam 21 while the respective dies 23 slide in the
direction toward the center of the lower die 13, namely in the
axial direction of the intermediate product W5. The involute
splines Sb parallel to the axial line of the gear formed at the
clutch spline section Pb are then formed into involute splines with
back taper Gb by the tips 23D of the dies 23.
92. After that, the upper die mounting base 12 is made to go up, to
push up the knockout pin 19 and make the flange 18 go up. This also
makes the cam 21 go up but, since the pin 22 provided in projection
with an inclination against the cam 21 is inserted in the pin
inserting hole 23H of the die 23, the respective dies 23 forcibly
slide in the direction opposite to the center of the lower die 13,
and the tip 23D of the die 23 is detached from the intermediate
product W6 on which is formed the involute spline with back taper
Gb.
93. To take out the intermediate product W6, the tip 23D of the die
23, after being detached from the intermediate product W6 so that
the involute spline with back taper Gb is not damaged by the tip
23D of the die 23, pushes down the knockout pin 20 and makes the
knockout cylinder 16 protrude, thus releasing the intermediate
product W6 from the lower die 13.
94. Next, the speed gear teeth forming process by the flow forming
of FIG. 1 (14) will be explained in detail.
95. The speed gear teeth forming process by flow forming consists
in finish performing, with the involute spline forming process of
FIG. 1 (12), speed gear teeth Ra rough-formed at the speed gear
section Pa into speed gear teeth Ga, while rotating the
intermediate product W7 around the shaft hole H, with reference to
the clutch spline section Pb having involute spline with back taper
Gb formed in the final finished dimensions.
96. FIG. 6 to FIG. 9 show an example of the apparatus for flow
forming used for executing the speed gear teeth forming process by
flow forming.
97. An apparatus for flow forming 7, intended to finish form
helical teeth Ra into helical teeth Ga, is constructed as described
below.
98. The apparatus for flow forming 7 is composed of a tail stock
unit 4 alternately rotatable in normal and reverse directions, a
chuck unit 5 for holding the intermediate product W7 in
collaboration with the tail stock unit 4, and a rolling die unit 6
driven by the rotation of the tail stock unit 4 for finish forming
helical teeth Ra into helical teeth Ga.
99. The tail stock unit 4 is constructed by fixing a synchronizing
gear 42, a receiving die 43 and a collet chuck 44 by means of a
bolt 45 to the tip of the tail stock 41, which is alternately
rotatable in normal and reverse directions.
100. The synchronizing gear 42 has teeth which protrude more than
the tail stock 41. The teeth are in phase with the helical teeth Ga
to be formed.
101. On the receiving die 43 is formed a concave part in the shape
of an involute spline corresponding to the involute spline with
back taper Gb formed at the clutch spline section Pb of the
intermediate product W7.
102. The chuck unit 5 is constructed by fixing a clamp die 52 and a
male cone 54 to a chuck receiving base 51, disposed to face the
tail stock unit 4 with a bolt 55. A stripper 53 disposed at the
outer circumference of the clamp die 52 is fastened to a rod
56.
103. As the chuck unit 5 is made to advance, the receiving die 43
of the tail stock unit 4, disposed face to face with the chuck unit
5, and the clamp die 52 of the chuck unit 5 hold the intermediate
product W7 by engaging the involute spline with back taper Gb
formed at the clutch spline section Pb of the intermediate product
W7 in the concave part in the shape of an involute spline formed in
the receiving die 43. This puts the helical teeth Ra in phase with
the synchronizing gear 42.
104. Moreover, the intermediate product W7 is held accurately
around the shaft hold H of the intermediate product W7, because it
is held as the male cone 54 of the chuck unit 5 is inserted in the
collet chuck 44 of the tail stock unit 4, thus flaring a claw
segment 44a of the collet chuck 44.
105. Furthermore, the stripper 53 is slidably disposed at the outer
circumference of the clamp die 52 fixed to the chuck receiving base
51 and fastened to the tip of the rod 56 passing through the chuck
receiving base 51 to slidably support a mounting base 57, to which
the base end of the rod 56 is fixed, in the axial direction of the
chuck receiving base 51.
106. The chuck unit 5 is constructed so as to release, after
formation of the helical teeth Ga, the holding of the intermediate
product W8 by the receiving die 43 and the clamp die 52 by making
the chuck receiving base 51 retreat by making the stripper 53
protrude by means of the rod 56.
107. The rolling die unit 6 is constructed of a movable carriage 61
which traverses against the tail stock 41, a rolling spindle 62
disposed parallel to the tail stock 41 through bearings 63, 63, a
driven gear 64 disposed in the rolling spindle 62 and engaging with
the synchronizing gear 42, and a rolling die 65.
108. Next, the motions of this apparatus for flow forming 7 will be
explained.
109. As the chuck unit 5 is made to advance, the receiving die 43
of the tail stock unit 4, disposed face to face with the chuck unit
4, and the clamp die 52 of the chuck unit 5 hold the intermediate
product W7. The movable carriage 61 of the rolling die unit 6
traverses against the tail stock 41 to engage the driven gear 64
with the synchronizing gear 42 and engage the rolling die 65 with
the helical teeth Ra, rough-formed at the speed gear section Pa of
the intermediate product W7.
110. The intermediate product W7 and the chuck unit 5 are made to
rotate by turning of the tail stock 41. In this case, the tail
stock 41 preferably makes normal rotation and reverse rotation
alternately at prescribed cycles.
111. On the other hand, the rotation of the tail stock 41 is
transmitted, through the synchronizing gear 42, the driven gear 64
and the rolling spindle 62, to the rolling die 65, and this rolling
die 65 turns in synchronization with the synchronizing gear 42.
112. As a result, the intermediate product W7, which is engaged
with the rolling die 65, is turned by the tail stock 41. While the
intermediate product W7 is turning with the rolling die 65, the
helical teeth Ra are finish formed into helical teeth Ga by forging
with the rolling die 65.
113. To take out the intermediate product W8 on which helical teeth
Ga are formed, the chuck receiving base 51 is made to retreat to
cancel holding of the intermediate product W8 by the receiving die
43 and the clamp die 52. The intermediate product W8 fit in the
clamp die 52 is inclined by making the stripper 53 protrude by
means of the rod 56.
114. The speed gear and the manufacturing method and apparatus
according to the present invention have so far been explained, by
taking, as an example, the speed gear W of the form as indicated in
FIGS. 11 (A) and 11 (B), realized in a way to form helical teeth Ga
as speed gear teeth at the speed gear section Pa. The object of the
present invention is not restricted to a speed gear of this form,
but may be modified as required within a range not deviating from
its purport.
115. To be more concrete, the speed gear W forming the subject of
the present invention includes a speed gear with flat teeth, in
addition to speed gear having helical teeth, as speed gear teeth
Ga, and further includes a speed gear having crowning Ca on the
tooth flank of the speed gear with Ga as shown in FIGS. 10 (C) and
10 (D) and also includes those not having crowning Ca, as a matter
of course.
116. In this case, by suitably selecting the shape of the rolling
die 65 of the apparatus for flow forming 7, when finish forming, by
forging with rolling die 65, speed gear teeth Ra, rough-formed at
the speed gear section Pa of the intermediate product W7, into
speed gear teeth Ga, it is possible to form crowning Ca on the
tooth flank of the teth of speed gear Ga at the same time.
117. Moreover, a speed gear W forming the subject of the present
invention includes speed gear in which the tip diameter Db of the
back tapered involute spline Gb formed on the clutch spline section
is larger than the root diameter Da of the speed gear teeth Ga
formed on the speed gear section Pa as indicated in FIG. 10 (B).
The clearance t of a groove Na formed between the speed gear
section Pa and the clutch spline section Pb is no more than 2 mm,
as also in a speed gear in which a partition Nb is formed between
the speed gear section Pa and the clutch spline section Pb, as
shown in FIG. 10 (C), etc., which were difficult to work within a
method of forming speed gear teeth Ga on the speed gear section Pa
by machining such as hobbing, etc. Speed gear in which the
clearance t of the groove Na formed at the speed gear section Pa
and the clutch spline section Pb is larger than 2 mm, as shown in
FIG. 10 (A), are also included, naturally.
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