Turning – Process of turning
Reexamination Certificate
2000-08-04
2002-07-09
Tsai, Henry (Department: 3722)
Turning
Process of turning
C082S001200, C082S001500, C082S082000
Reexamination Certificate
active
06415695
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for forming a spherical concave surface for supporting a body with a spherical convex surface, and, more specifically, to a method for forming a spherical concave surface suitable for supporting a shoe with a spherical convex surface at an end portion of a piston in an inclined plate-type compressor.
2. Description of Related Art
In a known inclined plate-type compressor, generally a pair of shoes each having a spherical convex surface engage an end portion of a piston. The rotational movement of an inclined plate rotated by a drive shaft is converted into the reciprocal movement of the piston via the engagement of the shoes with the end portion of the piston and the radial outer surface of the inclined plate. The piston compresses fluid by its reciprocal movement. Each shoe may have a flat surface engaging the radial outer side surface of the inclined plate, and a spherical convex surface engaging and supported by a spherical concave surface formed at the end portion of the piston.
FIG. 3
depicts a known inclined plate-type compressor. Each piston
1
is reciprocally inserted into corresponding cylinder bore
2
formed in cylinder block
3
. Crank chamber
4
is formed by cylinder block
3
and front housing
5
. Drive shaft
6
extends through crank chamber
4
, and is rotatably supported by cylinder block
3
and front housing
5
. Inclined plate
7
rotates integrally with drive shaft
6
via rotor
8
and may form a variable inclined plate angle with drive shaft
6
. The radial outer portion of inclined plate
7
runs through groove
11
formed at the end portion of piston
1
, when inclined plate
7
rotates. A pair of shoes
9
are provided at the end portion of piston
1
. Each shoe
9
has flat surface
9
a
slidably engaging the radial outer side surface of inclined plate
7
, and spherical convex surface
9
b
slidably engaging and supported by a pair of spherical concave surfaces
1
a
and
1
b
formed at the end portion of piston
1
. The rotational movement of inclined plate
7
is converted into the reciprocal movement of each piston
1
via the pair of shoes
9
.
FIG. 4
depicts a known method for forming spherical concave surfaces
1
a
and
1
b
at the end portion of piston
1
. Groove
11
, through which the radial outer portion of inclined plate
7
passes, is provided at the end portion of piston
1
. Cutting edge
14
of tool
12
(a cutting tool) is brought into contact with an inner side surface of groove
11
. At that time, central axis L
2
of supporting base
13
of tool
12
is set parallel to central axis L
1
of groove
11
. With tool
12
and piston
1
in this relative orientation, and while piston
1
is rotated around central axis L
1
of groove
11
, tool
12
is moved concordantly in first direction Y parallel to axis L
2
of supporting base
13
of tool
12
and in second directions X
1
and X
2
perpendicular to first direction Y. During this method, cutting edge
14
of tool
12
moves along an arced path, so that it moves from point P
1
to point P
3
through point P
2
. In such a manner, spherical concave surfaces
1
a
and
1
b
are formed about central axis L
1
of groove
11
.
In the above-described known forming method, however, when cutting edge
14
passes through point P
2
, the moving direction of supporting base
13
changes from direction X
2
to direction X
1
. Namely, when cutting edge
14
is moved along the arced form of spherical concave surface
1
a
, although supporting base
13
is moved in direction X
2
as cutting edge
14
forms a portion between points P
1
and P
2
, supporting base
13
is moved in direction X
1
as cutting edge
14
forms a portion between points P
2
and P
3
.
Consequently, a sudden recoil may occur in a power transmitting mechanism of a controlling machine (not shown) for moving supporting base
13
when the direction of movement changes from direction X
2
to direction X
1
at point P
2
. The generation of such a sudden recoil may not achieve a proper movement of cutting edge
14
, and spherical concave surfaces
1
a
and
1
b
may not be formed in the desired target shapes.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved method for formig a spherical concave surface in a desired shape without generating a sudden recoil in a controlling machine.
It is another object of the present invention to provide an improved method for forming a spherical concave surface suitable for supporting a shoe with a spherical convex surface at an end portion of a piston in an inclined plate-type compressor.
To achieve the foregoing and other objects, a method for forming a spherical concave surface according to the present invention is herein provided. The method for forming a spherical concave surface comprises the steps of bringing a tool into contact with a material to be formed, rotating the material around a predetermined axis, and moving the tool in a first direction parallel to a central axis of the tool and in a second direction perpendicular to the first direction for forming the spherical concave surface on the material about the predetermined axis. In this method, a first angle of the central axis of the tool relative to the predetermined axis is selected to be greater than or equal to, i.e., not less than, a second angle of a tangent at a first end of the spherical concave surface in a cross-sectional plane including the predetermined axis relative to the predetermined axis.
Further, the present invention provides a method for forming a spherical concave surface on an end portion of a piston of an inclined plate-type compressor. The method comprises the steps of: providing a groove on the end portion of the piston, in which groove the depth direction extends along a predetermined axis; bringing a tool into contact with an inner side surface of the groove; rotating the piston around the predetermined axis; and moving the tool in a first direction parallel to a central axis of the tool and in a second direction perpendicular to the first direction for forming the spherical concave surface on the inner side surface of the groove about the predetermined axis. The groove is adapted to receive a radial outer portion of a rotating inclined plate. In this method, a first angle of the central axis of the tool relative to the predetermined axis is selected to be greater than or equal to, i.e., not less than, a second angle of a tangent at a first end of the spherical concave surface in a cross-sectional plane including the predetermined axis relative to the predetermined axis.
In the method, the tool is moved in a single direction along the second direction while the tool is moved in a single direction along the first direction.
In the method according to the present invention, because the first angle is greater than or equal to, i.e., not less than, the second angle, the tool may be moved only in one direction, that is the second direction, when the spherical concave surface is formed. Because the moving direction of the tool does not change, a sudden recoil does not occur when the tool is moved by a power transmitting mechanism of a forming machine. A cutting edge of the tool may be moved along a properly arced route along a spherical concave surface to be formed, without any undesirable variation. Consequently, the spherical concave surface may be accurately formed in a desired target shape.
Further objects, features, and advantages of the present invention will be understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying figures.
REFERENCES:
patent: 4084458 (1978-04-01), Galley
patent: 4313355 (1982-02-01), Becker et al.
patent: 4584148 (1986-04-01), Rawlings et al.
patent: 4617845 (1986-10-01), Sasano et al.
patent: 4945792 (1990-08-01), Gardner
patent: 5209145 (1993-05-01), Baudermann
patent: 5417130 (1995-05-01), Dorsch
patent: 5765464 (1998-06-01), Morita
patent: 5950480 (199
Baker & Botts L.L.P.
Sanden Corporation
Tsai Henry
LandOfFree
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