Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Reexamination Certificate
2002-06-05
2004-03-23
Cuda Rosenbaum, I (Department: 3726)
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
C029S888022, C029S557000, C072S356000
Reexamination Certificate
active
06708406
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a shoe for a compressor.
2. Description of the Related Art
A compressor, that compresses a refrigerant gas, is built into a refrigerating circuit that is used as a vehicle air conditioner or the like. For example, a known variable-displacement-type swash-plate compressor has a plurality of cylinder bores
91
a
formed in a cylinder block
91
, as shown in
FIG. 9. A
piston
92
is accommodated in each cylinder bore
91
a
so as to be able to carry out a reciprocating motion. Further, a swash plate
93
is supported by a drive shaft, not shown, such that the swash plate
93
is rotatable synchronously with the drive shaft and is tiltable with respect to the drive shaft. A pair of shoes
94
are provided, on each side of the swash plate
93
, between the swash plate
93
and each piston
92
. As shown in
FIG. 10
, the upper surface of each shoe
94
forms a part of a spherical surface as a spherical surface portion
94
a
, and the lower surface of the shoe
94
forms approximately a plane surface as a plane surface portion
94
b
. A cylindrical portion
94
c
is formed in the middle between the upper portion and the lower portion via a round portion R.
In the compressor having the above structure, the swash plate
93
rotates synchronously with the drive shaft and makes an inclined movement with respect to the drive shaft, and a rotary motion of the swash plate
93
is converted into a linear reciprocating motion of the piston
92
in the cylinder bore
91
a
, via the shoes
94
, based on the rotation of the drive shaft, as shown in FIG.
9
. Suction, compression, and discharging of a refrigerant gas are carried out at the head end of the piston
92
, based on these motions. During this period, the spherical surface portion
94
a
of each shoe
94
slides on the surface of a spherical surface seat
92
a
of the piston
92
, and the plane surface portion
94
b
of the shoe slides on the surface of the swash plate
93
. Therefore, the shoe
94
is required to have high size precision and small surface roughness in order to allow a smooth sliding action.
Conventionally, the shoe
94
has been manufactured according to the following process which includes a cutting step and a shoe forming step.
Cutting Step
As shown in
FIG. 11
, a wire
70
comprising SUJ2 (JIS Japanese Industry Standard G4805), a high carbon chrome bearing steel, is provided. This wire
70
is cut into pieces to obtain cut pieces
71
in a cutting step S
90
.
Shoe Forming Step
The shoe forming step S
91
is then carried out. In a forging step S
91
a
, each cut piece
71
is forged with a forging die
95
, that has a spherical cavity
95
c
comprising a lower die
95
a
and an upper die
95
b
, to form a sphere as shown in FIG.
12
. As a result, an approximately spherical steel sphere
72
having a slight flash
72
a
is obtained, as shown in FIG.
13
.
Then, in a flash removing (deburring) step S
91
b
in
FIG. 11
, a flash (a burr) is removed by sandwiching the steel sphere
72
between two rotary casting boards, not shown, and by rotating the casting boards, thereby to obtain a flashless ball
73
.
Next, in a heat treating step S
91
c
, hardening and tempering are carried out to obtain a heat-treated ball
74
.
In a grinding step S
91
d
, the heat-treated ball
74
is ground with casting boards similar to those explained above and is ground with a grindstone, thereby to obtain a ground ball
75
. The hard ground ball
75
obtained in this way can also be used as a ball of a rolling bearing.
Further, the ground ball
75
is annealed in an annealing step S
91
e
, thereby to obtain an annealed ball
76
that has a slightly lower hardness than that of the ground ball
75
and that has no internal distortion.
Then, in a rotary grinding step S
91
f
, the annealed balls
76
and a slurry are put into a rotary grinder, not shown, and are rotated together. As a result, the annealed balls
76
are brought into contact with each other, and are mutually ground. Gloss is added to these balls, and stains adhered to the surfaces of these balls are removed.
Further, in a washing step S
91
g
, an ultrasonic cleaning is carried out to remove slight stains adhered to the surfaces. A visual inspection step S
91
h
is carried out, and an anticorrosive is then coated onto the balls in an anticorrosive processing step S
91
i
. As a result, a raw ball
77
having a true spherical shape is obtained.
In a pressing step S
91
j
, the raw ball
77
is pressed to obtain a material
78
formed in a shoe shape.
Further, in a heat treating step S
91
k
, hardening and tempering are carried out. Then, the shoe-shaped material is ground, to obtain a shoe shape and a surface coarseness within a standard, in a finish grinding step S
91
l
. The shoe-shaped material is further cleaned in a washing step S
91
m
, and is dried in a drying step S
91
n
to finally obtain a shoe
94
for a compressor.
The conventional manufacturing method employs the flash removing step S
91
b
and, therefore, the grinding step S
91
d
and the rotary grinding step S
91
f
are necessary. That is, as the steel sphere
72
is obtained in the forging step S
91
a
by using the forging die
95
comprising the lower die
95
a
and the upper die
95
b
, it is difficult to obtain a desired shape, and therefore, the cut piece
71
having a slightly larger volume than that of a desired shoe is obtained so that the flash (burr)
72
a
occurs. As a slight gap is formed between the upper die
95
b
and the lower die
95
a
of the forging die
95
, the flash
72
a
occurs in this gap.
According to the above conventional manufacturing method, however, the shoe
94
is manufactured from the raw ball
77
, after the raw ball
77
has been manufactured. Therefore, many steps such as the forging step S
91
a
, the flash removing process S
91
b
, the heat treating step S
91
c
, the grinding step S
91
d
, the annealing step S
91
e
, and the rotary grinding step S
91
f
are necessary. In addition, as the raw ball
77
is completed through the above steps, and thereafter, the raw ball
77
is again subjected to the pressing step S
91
j
that deforms the raw ball
77
to obtain the material
78
which is in turn subjected to the heat treating step S
91
l
and the finish grinding step S
91
i
. Therefore, an extremely large number of steps are carried out on the wire
70
. Consequently, the process takes a long time, and is expensive.
SUMMARY OF THE INVENTION
The present invention has been made in the light of the above problems. It is, therefore, an object of the present invention to provide a method of manufacturing a shoe for a compressor that can shorten the manufacturing time and can reduce the manufacturing cost.
In order to achieve the above object, according to the present invention, there is provided a method of manufacturing a shoe for a compressor comprising the steps of cutting a steel wire to obtain a cut piece, and forming a shoe for a compressor from the cut piece, wherein, in the cutting step, the wire is cut so that the cut piece has a volume approximately equivalent to that of a desired shoe, wherein the forming step comprises the steps of sequentially forging the cut piece with forging dies having three or more cavities to obtain a shoe-shaped material, and finishing said material by at least a heat treatment to obtain the shoe.
In this method, after the cut piece is obtained by cutting the wire into the cut piece having a volume approximately equivalent to that of a desired shoe in the cutting step, the shoe is manufactured in the forming step comprising the forging step and the finishing step. Therefore, a heat treating step, a grinding step and an annealing step which are carried out in a conventional manufacturing method to obtain a raw ball can be omitted.
Further, according to this method, the cut piece is cut in the cutting step so that it has a volume approximately equivalent to that of a desired shoe, and the cut piece is sequentially forged with forging dies
Furukawa Tadashi
Miura Yasuhiro
Nagao Kazuhiko
Tomita Masanobu
Cuda Rosenbaum I
Kabushiki Kaisha Toyota Jidoshokki
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