Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Reexamination Certificate
2000-06-30
2003-01-21
Tolan, Ed (Department: 3725)
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
C072S084000, C072S110000
Reexamination Certificate
active
06508094
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. H11-185310 filed on Jun. 30, 1999 and that of Japanese Patent Application No. 2000-174315, filed Jun. 30, 1999, including the specification, drawings and abstract of each, are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an internally-toothed member, and to a method and apparatus for molding same.
2. Description of the Related Art
In general, an automatic transmission employs a planetary gear unit which is composed of a sun gear, a pinion, a ring gear and a carrier. Gear elements such as the sun gear, the ring gear and the carrier are selectively operated by frictional engagement elements such as clutches and brakes, whereby a speed-change operation is made possible.
First and second rotational members in the automatic transmission are selectively coupled, for example, by engaging and disengaging a clutch. For this purpose, the clutch has a drum, a clutch hub, a plurality of clutch plates, a plurality of clutch discs, and a hydraulic servo. The drum is designed as an internally-toothed member which is coupled to the first rotational member and which is itself rotatably mounted. The clutch hub is mounted for rotation relative to the drum. The clutch plates are spline-engaged at their outer peripheral edges with the drum. The clutch discs are spline-engaged at their inner peripheral edges with the clutch hub. The hydraulic servo engages and disengages the clutch by selectively pressing the clutch plates and clutch discs together and releasing same.
The drum and the first rotational member are coupled to each other by a meshing engagement. For this purpose, a meshing portion is formed at a tip end of the drum by means of a molding method such as corrugation molding (Cam molding).
FIG. 2
is a longitudinal sectional view of the essential part of a drum having a meshing portion formed as a molded corrugation by the method of the related art.
FIG. 3
is an enlarged view of the meshing portion formed as the molded corrugation by the method of the related art.
In the drawings, drum
1
is shown as composed of a tubular trunk portion
12
and an annular disc portion
13
. A splined tooth
14
is formed at a predetermined position on an inner periphery of the trunk portion
12
, for example, by means of cutting. A meshing portion
15
is formed at a tip end of the trunk portion
12
by means of corrugation molding. The meshing portion
15
is composed of non-worked (non-processed) portions P
1
and worked (processed) portions P
2
. The non-worked portions P
1
and the worked portions P
2
are arranged alternately around the circumference with an equal spacing (pitch) therebetween. The worked portions P
2
, which remain equal in thickness to the non-worked portions P
1
, are extruded radially outwardly.
However, in the method of molding the drum
11
according to the related art, during formation of the meshing portion, the worked portions P
2
are extruded radially outwardly while remaining equal in thickness to the non-worked portions P
1
. This leads to a corresponding increase in diameter of the drum
11
and causes enlargement of the drum
11
Further, as the worked portions P
2
are extruded, step portions R
1
, R
2
between the non-worked portions P
1
and the worked portions P
2
become thinner. As a result, cracks are generated in the step portions R
1
, R
2
the drum becomes less durable. Furthermore, a corner portion Q of the inner peripheral surface of the meshing portion
15
may sag as illustrated in FIG.
3
. This reduces the quality of the drum
11
.
Further, a step for molding the tooth
14
and a step for extruding the worked portions P
2
both require man-hours of labor to the detriment of productivity in manufacture of the drum
11
. Besides, precision in positioning of the spline teeth
14
and of the meshing portion
15
suffers. As a result, the quality of the drum
11
also suffers.
Hence, slot extraction has been considered for forming the meshing portion.
FIG. 4
is a longitudinal sectional view of the relevant part of a drum having a meshing portion formed by the slot extraction of the related art.
FIG. 4
drawing shows a drum
21
as being composed of a tubular trunk portion
22
and an annular disc portion
23
. A spline tooth
24
is formed at a predetermined position on an inner periphery of the trunk portion
22
, for example by cutting. A meshing portion
25
is formed at a tip end of the trunk portion
22
by means of slot extraction. The meshing portion
25
is composed of non-worked portions P
3
and worked portions P
4
. The non-worked portions P
3
and the worked portions P
4
are arranged alternately around the circumference with equal spacing (pitch) therebetween. The worked portions P
4
are punched so that slots are formed.
However, a centrifugal force is applied to the trunk portion
22
as the drum
21
rotates. Thus, if the rotational speed of the drum
21
becomes high in use in the automatic transmission the non-worked portions P
3
may be deformed as shown in the drawing. As a result, the durability of the drum
21
may suffer.
Further, since the process requires a separate molding step to form the spline tooth
24
and a punching step to form the worked portions P
4
, the process becomes labor-intensive and the productivity in manufacture of the drum
21
suffers. Besides, precision in positioning of the spline teeth
24
relative to the meshing portion
25
is difficult to attain, to the detriment of drum quality.
SUMMARY OF THE INVENTION
Accordingly, the objective of the present invention is to provide a solution to the above-mentioned problems of the related art. Thus, it is an object of the present invention to provide an internally-toothed member, a method of molding the internally-toothed member, and an apparatus for molding the internally-toothed member such that its size can be reduced, while enhancing its quality, durability and productivity in manufacture.
To achieve the forgoing objects, according to a first aspect of the present invention, there is provided an internally-toothed member comprising a first cylinder portion and a second cylinder portion which is larger in diameter than the first cylinder portion, wherein first and second internal teeth are formed so as to protrude radially inwardly from inner peripheral surfaces of the first and second cylinder portions, respectively.
In this case, since the meshing portion is formed with the second internal teeth protruding from the inner peripheral surface of the second cylinder portion, there is no need to increase the diameter of the internally-toothed member. Accordingly, the internally-toothed member can be reduced in size.
Further, the space between the second internal teeth and the concave portion does not thin during formation of the second internal teeth. Therefore, it is possible to prevent generation of cracks and enhance durability of the internally-toothed member. In addition, since there is no sagging at the inner peripheral surface of the meshing portion, the quality of the internally-toothed member can be further enhanced.
Further, the second internal teeth portion is integrally coupled to the concave portion. Therefore, even if a centrifugal force has been applied to the internally-toothed member during rotational movement thereof, the second internal teeth portion, the concave portion and the like are not deformed. Accordingly, the durability of the internally-toothed member can be enhanced.
In the first aspect of the present invention, the internally-toothed member may be a drum of a clutch. In this case, the second teeth may be separated by axially formed grooves.
In this case, the grooves are formed in the inner peripheral surface of the second internal teeth portion so as to extend in the axial direction. Accordingly, lubricating oil circulating inside the internally-toothed member can easily be drawn out through the groove. Also, formation of the grooves leads to a corresponding decreas
Fukukawa Osamu
Gotou Masahiro
Katou Hiroshi
Nagai Hideyuki
Saitou Masaki
Aisin AW Co. Ltd.
Tolan Ed
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