Information
-
Patent Grant
-
6615583
-
Patent Number
6,615,583
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Date Filed
Tuesday, December 4, 200123 years ago
-
Date Issued
Tuesday, September 9, 200321 years ago
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Inventors
-
Original Assignees
-
Examiners
- Look; Edward K.
- Leslie; Michael
Agents
- Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
A pressurizing apparatus includes a fixed portion, an input shaft acting directly in an axial direction with respect to the fixed portion, an output shaft extending coaxially with the input shaft to slide with respect to the fixed portion and the input shaft, a direct-connecting mechanism directly connecting the output shaft and the input shaft and causing the input shaft to directly act with respect to the fixed portion to thereby rapidly carry the output shaft with respect to the fixed portion, a fluid pressure mechanism connecting the input shaft and the output shaft in a fluid manner and causing the input shaft to directly act with respect to the output shaft to thereby increase biasing of the input shaft by Pascal's law and transmit the biasing to the output shaft, and a control mechanism actuated by biasing applied by the input shaft to control fluid connection of the input shaft and the output shaft to each other. The control mechanism is directly actuated by biasing of the input shaft applied by the input shaft. Therefore, the apparatus need not include a special actuator for driving the control mechanism and can be formed with a simple structure and at low cost.
Description
TECHNICAL FIELD
The present invention relates to a pressurizing apparatus used for pressurization of a metal mold in sheet-metal presswork and clamping of a metal mold in die casting and injection molding.
BACKGROUND ART
As a mechanism for applying thrust to a metal mold so as to carry out pressurization of the metal mold in sheet-metal presswork and the like and clamping of the metal mold in die casting and injection molding, there are mainly the following two mechanisms. One is a motor-driven pressurizing mechanism in which a rotational motion of a motor is converted into a linear motion by a mechanism such as a screw feeding mechanism for converting a rotational motion into a linear motion and an output shaft is moved forward and rearward by the linear motion. The other is a hydraulic pressurizing mechanism in which a hydraulic pump is actuated by a rotational driving force of a motor to cause a hydraulic cylinder to directly act by oil discharged from the hydraulic pump to move an output shaft connected to the hydraulic cylinder forward and rearward.
By using any of the above mechanisms, however, it is difficult to obtain both high-speed movement and high thrust because a motor capacity is limited to a small value due to circumstances such as manufacturing cost. In other words, a carrying speed has to be reduced by reducing a speed reducing ratio of a powertrain or the like so as to obtain high-speed movement while thrust has to be reduced by increasing the speed reducing ratio of the powertrain or the like so as to obtain high thrust.
Therefore, an object of the present invention relates to a pressurizing apparatus used for pressurization of a metal mold in sheet-metal presswork and the like and clamping of a metal mold in die casting, injection molding, and the like and is to provide a low-cost pressurizing apparatus with high productivity by combining a direct-connecting mechanism for moving an output shaft with low thrust and at a high speed and a fluid pressure mechanism for driving the output shaft at a low speed and with high thrust with each other.
DISCLOSURE OF THE INVENTION
An invention described in claim
1
is formed of a pressurizing apparatus including a fixed portion, an input shaft for acting directly in an axial direction with respect to the fixed portion, an output shaft extending coaxially with the input shaft to slide with respect to the fixed portion and the input shaft, a direct-connecting mechanism for directly connecting the output shaft and the input shaft and for causing the input shaft to directly act with respect to the fixed portion to thereby rapidly carry the output shaft with respect to the fixed portion, a fluid pressure mechanism for connecting the input shaft and the output shaft in a fluid manner and for causing the input shaft to directly act with respect to the output shaft to thereby increase biasing of the input shaft by Pascal's law and transmit the biasing to the output shaft, and a control mechanism actuated by biasing applied by the input shaft to control fluid connection of the input shaft and the output shaft to each other.
The pressurizing apparatus according to the invention described in claim 1 operates as follows in a step such as pressurization of a metal mold in sheet-metal presswork and clamping of a metal mold in injection molding. The present apparatus directly connects the output shaft to the input shaft to rapidly carry the output shaft in a reciprocating stroke excluding a vicinity of a turning point between going and returning of the metal mold. By this rapid carrying, it is possible to move the metal mold with the output shaft at a high speed. The present apparatus cancels direct connection and causes the input shaft to directly act with respect to the output shaft at points of a stroke in the vicinity of the turning point. Thus, the control mechanism is actuated to connect the input shaft and the output shaft to each other in a fluid manner. By this fluid connection, biasing by the input shaft can be increased by Pascal's law and transmitted to the metal mold through the output shaft.
As a result, according to the present invention, it is possible to provide the pressurizing apparatus by which both high-speed movement of the metal mold and pressurization of the metal mold with high thrust can be obtained even if an inexpensive low-capacity motor (drive source) is used. Because it is possible to shorten processing time by moving the metal mold at a high speed, productivity is increased.
In the invention, the control mechanism for controlling fluid connection of the input shaft and the output shaft to each other is directly actuated by biasing of the input shaft applied by the input shaft. Therefore, the apparatus according to the invention does not need to have a special actuator for driving the control mechanism and can be formed with a simple structure at low cost.
An invention described in claim
2
is formed of a pressurizing apparatus according to claim
1
in which the input shaft is caused to act directly by a servomotor in the axial direction with respect to the fixed portion through a rotation/direct-action converting mechanism.
According to the invention described in claim
2
, in addition to advantages of the invention described in claim
1
, there are the following advantages. In other words, because the servomotor has great general versatility and it is possible to easily control switching between normal and reverse rotations, timing of switching, a rotation speed, and the like of the servomotor, it is possible to swiftly change processing conditions such as a direct-acting stroke of the output shaft and a pressurizing force without using a complicated apparatus.
An invention described in claim
3
is formed of a pressurizing apparatus according to claim
2
in which the rotation/direct-action converting mechanism is a ball screw-nut mechanism and has a ball screw supported for rotation by the fixed portion and a nut fixed to the input shaft.
According to the invention described in claim
3
, in addition to advantages of the invention described in claim
2
, there are the following advantages. Because the ball screw can be rotated smoothly at a high speed, it is possible to further shorten the processing time and to maintain a long life of the servomotor.
An invention described in claim
4
is formed of a pressurizing apparatus according to claims
1
to
3
in which the fluid pressure mechanism includes a first fluid chamber biased by the input shaft by causing the input shaft to directly act with respect to the output shaft and a second fluid chamber having a larger pressurizing area than the first fluid chamber to bias the output shaft and the control mechanism opens a first fluid path between the first fluid chamber and the second fluid chamber to connect the input shaft and the output shaft in a fluid manner.
According to the invention described in claim
4
, in addition to advantages of the inventions described in claims
1
to
3
, there are the following advantages. Because the fluid connection of the input shaft and the output shaft to each other can be carried out by only opening the first flow path by the control mechanism, it is possible to form the apparatus simply.
An invention described in claim
5
is formed of a pressurizing apparatus according to claim
4
in which the control mechanism includes a separating mechanism disposed in the first fluid path to separate the first fluid path and to cancel the separation by pressure in the first fluid chamber increased by biasing applied by the input shaft.
According to the invention described in claim
5
, in addition to advantages of the invention described in claim
4
, there are the following advantages. The direct-connection of the output shaft and the input shaft to each other is canceled at points of the stroke in the vicinity of the turning point between going arid returning of the metal mold and the pressure in the first fluid chamber is increased by relative sliding of both the shafts. Because the separating mechanism is actuated by this increase in pressure to open the first fluid path, it is possible to automatically shift to transmission of thrust from the input shaft to the output shaft by the fluid pressure mechanism.
An invention described in claim
6
is formed of a pressurizing apparatus according to claim
4
or
5
in which the second fluid chamber has a second fluid path communicating with a third fluid chamber provided separately from the first fluid chamber and the second fluid path is open while rapid carrying by the direct-connecting mechanism is carried out and is closed by a closing mechanism actuated by the pressure of the first fluid chamber increased by the biasing by the input shaft after direct connection by the direct-connecting mechanism is cancelled.
According to the invention described in claim
6
, in addition to advantages of the invention described in claim
4
or
5
, there are the following advantages. A capacity of the second fluid chamber is rapidly changed by biasing of the output shaft itself in rapid movement of the output shaft by rapid carrying. Therefore, the second fluid path through which fluid in the second fluid chamber flows in and out according to the change of the capacity is provided and connected to the third fluid chamber and the second fluid path is closed after the rapid carrying is completed to automatically shift to transmission of thrust from the input shaft to the output shaft by the fluid pressure mechanism.
An invention described in claim
7
is formed of a pressurizing apparatus according to claim
6
further including a closing mechanism for closing the second fluid path at pressure lower than pressure at which the separation by the separating mechanism is cancelled.
According to the invention described in claim
7
, in addition to advantages of the invention described in claim
6
, there are the following advantages. After the rapid carrying is completed, the first fluid path is opened following closing of the second fluid path and switching of operation from the rapid carrying to high-thrust pressurization is carried out automatically. Therefore, it is unnecessary to especially provide means for synchronizing operations of the direct-connecting mechanism and control mechanism and it is possible to obtain the present pressurizing apparatus at low cost and with a simple structure.
An invention described in claim
8
is formed of a pressurizing apparatus according to claim
7
in which magnets for retaining a separating member in respective positions corresponding to a separating state and a separation canceling state of the first fluid path are disposed in the control mechanism in the separating mechanism.
The invention described in claim
8
has the following advantages in addition to advantages of the invention described in claim
7
. In other words, without newly providing a pressure sensor and an actuator, it is possible to maintain the separating mechanism in the separating state until internal pressure of the first fluid chamber increases to pressure at which the closing mechanism is actuated. It is also possible to maintain the separating mechanism in the separation canceling state if a pressure difference between the first fluid chamber and the second fluid chamber disappears after the separation by the separating mechanism is cancelled temporarily. Thus, it is possible to keep the first fluid path open and rearward movement of the output shaft by the fluid pressure mechanism is carried out smoothly. Therefore, it is possible to obtain the pressurizing apparatus according to the invention at low cost and with a simple structure. There is not especially a fear of trouble.
An invention described in claim
9
is formed of a pressurizing mechanism according to claims
1
to
8
in which the direct-connecting mechanism is formed by disposing an engaging member in one of the input shaft and the output shaft and disposing an engaged member in the other, direct connection of the input shaft and the output shaft to each other by the engaging member and the engaged member is maintained by biasing of the output shaft by the input shaft, and the direct connection of the input shaft and the output shaft to each other is cancelled when the biasing of the output shaft by the input shaft is attenuated.
The invention described in claim
9
has the following advantages in addition to advantages of the inventions described in claims
1
to
8
. Because direct-connection of the input shaft and the output shaft to each other is maintained and cancelled by controlling biasing of the output shaft by the input shaft in the direct-connecting mechanism, is it unnecessary to provide a special actuator for driving the direct-connecting mechanism and sensors and the like and it is possible to form the apparatus at low cost and with a simple structure.
An invention described in claim
10
is formed of a pressurizing apparatus according to any one of claims
4
to
9
in which the first fluid chamber is defined by an outer peripheral portion of the input shaft, a first piston provided to the outer peripheral portion, and a first cylinder formed inside the output shaft, the second fluid chamber and the third fluid chamber are defied by an outer peripheral portion of the output shaft, a second piston provided to an axial intermediate portion of the outer peripheral portion, and a second cylinder formed inside the fixed portion and are disposed on opposite sides of the second piston in an axial direction of the output shaft.
The invention described in claim
10
has the following advantages in addition to advantages of the inventions described in claims
4
to
9
. In other words, because the pressurizing apparatus according to the invention has a simple structure formed by inserting the input shaft into the output shaft formed in a tubular shape and inserting the output shaft into the fixed portion, it is possible to easily assemble the apparatus. By arranging the second fluid chamber and the third fluid chamber in the axial direction inside the second cylinder, it is possible to simply form the entire apparatus in a small size.
An invention described in claim
11
is formed of a pressurizing apparatus according to claim
10
in which the third fluid chamber has a sub-piston moved by biasing by the output shaft to absorb the biasing of the output shaft.
The invention described in claim
11
has the following advantages in addition to advantages of the invention described in claim
10
. In other words, because the third fluid chamber has the sub-piston for absorbing biasing of the third fluid chamber by the output shaft, pressurization by the output shaft can be carried out without hindrance.
An invention described in claim
12
is formed of a pressurizing apparatus according to claim
10
or
11
in which the first fluid path is formed of a passage hole formed in the output shaft and connecting an outer peripheral side and an inner side of the output shaft and the second fluid path is formed of a passage hole formed in the second piston and connecting axial opposite outer faces of the second piston.
The invention described in claim
12
has the following advantages in addition to advantages of the invention described in claim
10
or
11
. Because the connecting holes forming the respective fluid paths are formed as partitioning members for the respective fluid chambers, the structure is simple and can be processed easily. As compared with a case of disposing a pipe and the like outside the apparatus, resistance of fluid is smaller and there is no fear of leakage of fluid to an outside.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a side portion sectional view of a pressurizing apparatus according to the present invention and showing an initial state before an output shaft starts high-speed movement.
FIG. 2
is a side portion sectional view of the pressurizing apparatus according to the invention and showing a state in which the high-speed movement of the output shaft by connection of the output shaft to an input shaft is completed.
FIG. 3
is a side portion sectional view of the pressurizing apparatus according to the invention and showing a state in which the output shaft is separated from the input shaft and pressurized by a hydraulic mechanism.
FIG. 4
is a front view of a control mechanism of the pressurizing apparatus according to the invention.
FIG. 5
is a sectional view taken along a line A—A in FIG.
4
and showing a section and peripheral portions of the control mechanism.
FIG. 6
is a sectional view taken along a line C—C in FIG.
4
.
FIG. 7
shows a shape of a separating plate.
THE BEST MODE FOR CARRYING OUT THE INVENTION
The preferred embodiment of the present invention will be described below by reference to the drawings.
Although a direction of an arrow A in the drawings is described as an upward direction of the pressurizing apparatus according to the invention, this direction is defined for convenience in description and does not limit a disposition attitude of the apparatus. The pressurizing apparatus according to the invention may be disposed in an orientation different from that in the description, e.g., sideways.
First, a general outline of the pressurizing apparatus according to the embodiment will be described. In
FIGS. 1
to
3
, a reference numeral
1
designates an input shaft,
2
an output shaft,
3
a fixed portion,
4
a direct-connecting mechanism,
5
a control mechanism, and
6
a hydraulic mechanism (fluid pressure mechanism).
An input shaft
1
is formed to be able to directly act in an axial direction of the input shaft
1
with respect to the fixed portion
3
by driving of a drive source. The input shaft
1
directly acts while being directly connected to the output shaft
2
by the direct-connecting mechanism
4
to rapidly carry the output shaft
2
with respect to the fixed portion
3
. When thrust of the input shaft
1
biases the output shaft
2
, the direct-connecting mechanism
4
maintains a direct-connected state due to the biasing. When the biasing disappears, the direct-connected state is cancelled. Therefore, if the input shaft
1
is stopped, the direct connection of the input shaft
1
and the output shaft
2
to each other is cancelled.
If the input shaft
1
acts directly in a state in which the direct connection of the input shaft
1
and the output shaft
2
to each other is cancelled, the control mechanism
5
is actuated by biasing by the input shaft
1
. The control mechanism
5
connects the input shaft
1
and the output shaft
2
in a fluid manner through oil by the hydraulic mechanism
6
disposed midway between the input shaft
1
and the output shaft
2
. By sliding the input shaft
1
with respect to the output shaft
2
, the hydraulic mechanism
6
increases the thrust of the input shaft
1
by Pascal's law and transmits the thrust to the output shaft
2
and the output shaft
2
is pressurized with high thrust. As a result, both high-speed movement and high-thrust pressurization of the output shaft
2
can be obtained and productivity can be improved.
In the invention, because the direct-connecting mechanism
4
and the control mechanism
5
are actuated by only the thrust of the input shaft
1
, switching between the high-speed movement and the high-thrust pressurization can be carried out by only controlling the thrust of the input shaft
1
, i.e., a drive source of the input shaft
1
. Therefore, it is unnecessary to especially provide a special actuator for switching, a device for controlling the actuator, and the like and the pressurizing apparatus according to the invention is advantageous in that the apparatus can be produced to be compact and at low cost.
Next, details of a structure of the pressurizing apparatus according to the embodiment will be described.
The input shaft
1
is formed to include a pillar-shaped input shaft main body
11
extending vertically and a first piston
12
added in a step shape onto an outer peripheral side face of the input shaft main body
11
. More specifically, the input shaft main body
11
is formed into a circular-cylindrical shape, a first piston
12
is formed as a circular ring-shaped step portion concentric with the input shaft main body
11
throughout a periphery of the side face of an upper portion of the input shaft main body
11
. The input shaft main body
11
is formed into the circular-cylindrical shape and the first piston
11
is formed into the circular ring shape in order to simplify the structure and to facilitate manufacturing and processing. Sliding portions of the output shaft and the fixed portion are also formed to have circular sectional shapes for the same reason.
The input shaft main body
11
is formed with a cap hole
13
extending upward from a bottom face of the input shaft main body
11
and a nut
71
which is a direct-acting body is fixed into a hole formed in a solid portion at an upper portion of the cap hole
13
through a keyway. The nut
71
is combined with a ball screw
72
as a vertically extending rotating body to form a ball screw-nut mechanism
7
as a rotation/direct-action converting mechanism together with the ball screw
72
. Bearings
73
,
73
are disposed on an upper end side of the ball screw
72
and an upper plate
34
of the fixed portion
3
is sandwiched between the bearings
73
,
73
from above and below. Thus, an upper side of the ball screw
72
is supported for rotation with respect to the fixed portion
3
and a lower side of the ball screw
72
is supported by the nut
71
fixed to the solid portion of the input shaft
1
. A tip end portion of the ball screw
72
projecting downward from the nut
71
is inserted into the cap hole
13
. The ball screw
72
is rotated by a servomotor (not shown) as a rotation drive source fixed on a fixed portion
3
side through a transmission gear such as a belt disposed on an upper end side of the ball screw
72
. The nut
71
directly acts on the ball screw
72
in response to rotation of the ball screw
72
. In other words, by rotating the ball screw
72
, the input shaft
1
directly acts in a vertical direction, i.e., an axial direction.
Because an outer periphery of the input shaft
1
is formed into a circular shape, the input shaft
1
rotates relatively to the output shaft
2
when a rotating force is applied to the input shaft
1
. In order to prevent this relative rotation, the nut
71
and the ball screw
72
are fixed to positions offset from an axial center of the input shaft
1
.
Although the ball screw-nut mechanism
7
is employed as the rotation/direct-action converting mechanism in the embodiment because importance is placed on high-speed and smooth direct acting of the input shaft
1
and reliability of actuation, it is also possible to employ other combinations such as a rack-and-pinion mechanism and a rotating crankshaft mechanism as a mechanism for converting a rotational motion into a linear motion.
The output shaft
2
is formed to have a tubular output shaft main body
21
in which the input shaft
1
is housed for sliding with respect to the output shaft main body
21
, a first cylinder
22
formed on an inner peripheral side face of the output shaft main body
21
to cooperate with the first piston, and a second piston
23
added in a step shape onto an outer peripheral side face of the input shaft main body
21
.
More specifically, the output shaft
2
is formed as follows. The output shaft main body
21
includes an output shaft tip end portion
24
in a shape of a closed-end cylinder, a cylindrical valve body
25
connected and fixed to an upper portion of the output shaft tip end portion
24
, and a cylindrical first cylinder tube
26
connected and fixed to an upper portion of the valve body
25
. The output shaft main body
21
is formed in a cylindrical shape extending coaxially with the input shaft
1
as a whole. To the upper portion of the output shaft main body
21
, a guide plate
27
for guiding sliding of the output shaft
2
and the fixed portion
3
with respect to each other and for preventing rotation of the output shaft
2
and the fixed portion
3
with respect to each other is fixed. The guide plate
27
has at a peripheral edge portion thereof a plurality of guide holes
271
to be engaged with guide rods
33
provided to an upper face of a fixed portion main body
31
and has in the vicinity of a central portion of the guide plate
27
a rather large guide plate center hole
272
through which the ball screw
72
is inserted.
An inside diameter of the valve body
25
is set to be slightly larger than an outside diameter of the input shaft main body
11
. At an inner peripheral portion
251
of the valve body
25
, a ring-shaped sealant
251
a
and a skid
251
b
are disposed. The input shaft main body
11
and the valve body
25
can slide with respect to each other in a watertight manner due to the sealant
251
a
. The skid
251
b
is a spacer for preventing damage and the like due to direct contact of the outer peripheral portion of the input shaft main body
11
and the inner peripheral portion
251
of the valve body
25
with each other. Other skids which will be described later are also spacers for preventing direct contact of the members with each other, the members sliding with respect to each other.
The first cylinder
22
is formed on an inner peripheral face of the first cylinder tube
26
. An inside diameter of the first cylinder
22
is set to be slightly larger than an outside diameter of the first piston
12
. A ring-shaped sealant
121
a
and a skid
121
b
are disposed at an outer peripheral portion of the first piston
12
and the first cylinder
22
can slide with respect to the first piston
12
in a watertight manner due to the sealant
121
a.
Between the input shaft
1
and the output shaft
2
, a first oil chamber (first fluid chamber)
61
defined by the outer peripheral side face of the input shaft main body
11
and an inner peripheral face of the first cylinder
22
and pressurized by the first piston
12
is formed. As a result, the first oil chamber
1
is biased by the input shaft
1
.
An inside diameter of the output shaft tip end portion
24
is set to be sufficiently larger than the outside diameter of the input shaft main body
11
such that the input shaft main body
11
can move vertically and relatively without resistance while being inserted into the output shaft tip end portion
24
.
Thus, the input shaft
1
and the output shaft
2
can slide with respect to each other. An outside diameter of the valve body
25
is set to be larger than outside diameters of the output shaft tip end portion
24
and the first cylinder tube
26
. Thus, the valve body
25
forms step portions between the output shaft tip end portion
24
arid the first cylinder tube
26
, i.e., the circular ring-shaped second piston
23
added in the step shape to the outer peripheral side face of the output shaft main body
21
. In order to apply high thrust to the output shaft
2
, a pressurizing area S
2
of the second piston
23
(step) is set to be sufficiently larger than a pressurizing area S
1
(step) of the first piston
12
.
The fixed portion
3
includes the tubular fixed portion main body
31
through which the output shaft
2
is inserted for relative sliding and the second cylinder
32
formed on an inner peripheral side face of the fixed portion main body
31
to cooperate with the second piston.
The fixed portion main body
31
is formed to have a base plate
311
having a circular through hole
311
a
, a cylindrical second cylinder tube
312
connected and fixed to an upper portion of the base plate
311
, and an intermediate plate
313
connected and fixed to an upper portion of the second cylinder tube
312
and having a circular through hole
313
a
. Axial centers of the through holes
311
a
and
313
a
and the second cylinder tube
312
are aligned with each other and the fixed portion main body
31
is formed into a cylindrical shape as a whole.
To an upper face of the intermediate plate
313
, one ends of the plurality of guide rods
33
inserted through the guide holes
271
in the guide plate
27
are secured. The guide rods
33
extend upward and the other ends of the guide rods
33
are connected to the upper plate
34
. The upper plate
34
supports the upper end of the ball screw
72
for rotation as described above.
An inside diameter of the through hole
311
a
in the base plate
311
is set to be slightly larger than the outside diameter of the output shaft tip end portion
24
. At an inner peripheral portion of the through hole
311
a
, a ring-shaped skid
311
b
is disposed such that the output shaft main body
21
can smoothly slide through the through hole
311
a
without rattling. On an upper face side of the base plate
311
, a ring-shaped sub-piston
65
is disposed through an auxiliary spring
64
. The sub-piston
65
has at inner and outer peripheral portions thereof ring-shaped sealants
65
a
and
65
b
to slide in a watertight manner with respect to the output shaft main body
21
and the second cylinder
32
. Thus, oil leakage from a third oil chamber
63
which will be described later to an outside is prevented.
An inside diameter of the second cylinder tube
312
, i.e., an inside diameter of the second cylinder
32
is set to be slightly larger than an outside diameter of the second piston
23
. A ring-shaped sealant
231
a
and a skid
231
b
are disposed at an outer peripheral portion of the second piston
23
and the second piston
23
and the second cylinder
32
can slide with respect to each other in a watertight manner due to the sealant
231
a.
An inside diameter of the through hole
313
a
in the intermediate plate
313
is set to be slightly larger than an outside diameter of the first cylinder tube
26
. A ring-shaped sealant
313
b
and a skid
313
c
are disposed at an inner peripheral portion of the through hole
313
a
and the first cylinder tube
26
and the intermediate plate
313
can slide with respect to each other in a watertight manner due to the sealant
313
b.
Between the output shaft
2
and the fixed portion
3
, a second oil chamber (second fluid chamber)
62
and the third oil chamber (third fluid chamber)
63
defined by an outer peripheral side face of the output shaft
1
and an inner peripheral face of the second cylinder
22
are formed. The second oil chamber
62
is formed on an upper side of the second piston
23
and the third oil chamber
63
is formed on a lower side through the second piston
23
.
The second oil chamber
62
transmits biasing applied to the first oil chamber
61
by the first piston
12
to the second piston
23
in a state in which the second oil chamber
62
communicates with the first oil chamber
61
and is separated from the third oil chamber
63
. In this transmission, hydraulic pressures of the first oil chamber
61
and the second oil chamber
62
communicating with each other are the same as each other. However, as described above, the pressurizing area S
2
of the second oil chamber
62
by the second piston
23
is set to be larger than the pressurizing area SI of the first oil chamber
61
by the first piston
12
. Therefore, biasing by the first piston
12
is increased according to a ratio S
2
/S
1
between the pressurizing areas of the first oil chamber
61
and the second oil chamber
62
by Pascal's law and transmitted to the second piston
23
.
The third oil chamber
63
communicates with the second oil chamber
62
when the second piston
23
is carried rapidly with the output shaft
2
to increase or decrease a capacity of the second oil chamber
62
. The third oil chamber
63
has functions as an oil reservoir in which oil flowing from the second oil chamber
62
is stored and as a pump chamber for causing the oil to flow into the second oil chamber
62
. Because both the second oil chamber
62
and the third oil chamber
63
are provided within the second cylinder tube, vertically, and in series, a structure is simple and it is possible to make the apparatus compact. It is possible to obtain the same cross-sectional areas of the second oil chamber
62
and the third oil chamber
63
by making the outside diameters of the output shaft tip end portion
24
and the first cylinder tube
26
the same as each other. If the cross-sectional areas are the same, it is possible to make amounts of changes of the capacities of the second oil chamber
62
and the third oil chamber
63
the same as each other and fluid can move smoothly between both the oil chambers.
If the output shaft
2
moves down in a state in which connection of the second oil chamber
62
and the third oil chamber
63
to each other is cancelled, the third oil chamber
63
is biased downward through the second piston
23
. This biasing can be absorbed by downward movement of the sub-piston
65
biased upward by the auxiliary spring
64
.
The direct-connecting mechanism
4
has an engaging member at an upper portion of the input shaft
1
, has an engaged member at an upper portion of the output shaft
2
, and directly connects the input shaft
1
and the output shaft
2
by engagement of the members with each other. A biasing member for canceling the engagement acts on the engaging member. A set member for setting the engaging member in a state in which the engaging member can be engaged with the engaged member is disposed at an upper portion of the fixed portion
3
. It is also possible that the engaging member is disposed at the output shaft and that the engaged member is disposed at the input shaft.
A lock arm
41
as the engaging member has one end pivoted on the upper portion of the input shaft main body
11
and the other projecting from the center hole
272
formed in the guide plate
27
, and is engaged from above with a recessed portion
42
as the engaged member formed at an edge portion of the guide plate center hole
272
. The lock arm
41
has a projection
411
at a portion of the lock arm
41
to be engaged with the recessed portion
42
. A lock arm spring
43
as abiasing member is disposed at a pivoted portion of the lock arm
41
and biases the lock arm
41
in such a direction that the lock arm
41
moves away from the recessed portion
42
.
A lock arm returning roller
44
as the set member is disposed in an downward orientation at the upper plate
34
and pushes the lock arm
41
to a position facing the recessed portion
42
against a biasing force of the lock arm spring
42
when the input shaft
1
is in an uppermost position shown in FIG.
1
.
The control mechanism
5
will be described by reference to
FIGS. 4
to
7
. The control mechanism
5
is provided to the valve body
25
and formed to include first oil paths (first fluid paths)
51
for connecting the first oil chamber
61
and the second oil chamber
62
, second oil paths (second fluid paths)
52
for connecting the second oil chamber
62
and the third oil chamber
63
, a separating mechanism
53
for separating the first oil paths
51
and canceling the separation, and a closing mechanism
54
for closing the second oil paths
52
and canceling the closing.
The first oil paths
51
are formed of holes formed in the output shaft
2
and connecting an outer peripheral portion side and an inner portion side of the output shaft
2
. The second oil paths
52
are formed of holes formed in the second piston
23
and connecting an axial upper face side and an axial lower face side of the second piston
23
.
The first oil paths
51
and the second oil paths
52
are formed in a peripheral wall portion
251
of the valve body
25
where the second piston
23
is formed. In the peripheral wall portion
251
, a groove
25
a
formed throughout a periphery at an axial intermediate portion of an outer peripheral face of the peripheral wall portion
251
, vertical holes
25
b
passing through the peripheral wall portion
251
from an upper face side to a lower face side to intersect the groove
25
a
, and horizontal holes
25
c
respectively extending from the vertical holes
25
b
and communicating with an inner face side of the peripheral portion
25
are formed. An upper peripheral wall portion
251
a
above the groove
25
a
has a small outside diameter and there is a gap B between the upper peripheral wall portion
251
and the second cylinder
32
. Each the vertical hole
25
b
is formed of an upper vertical hole
25
b
1
having a large inside diameter and a lower vertical hole
25
b
2
having a small inside diameter and divided into the upper and lower portions at the groove
25
a
. A movable pin
541
as a valve body of the closing mechanism
54
is disposed in each the upper vertical hole
25
b
1
.
Each the first oil path
51
is formed by connecting the upper hole
25
b
1
of the vertical hole
25
b
and the horizontal hole
25
c
. Each the second oil path
52
is formed of the lower portion
25
b
2
of the vertical hole
25
b
and communicates with an upper face side of the valve body
25
, i.e., the upper face side of the second piston
23
through the groove
25
a
and the gap B. Six (a plurality of) first oil paths
51
and second oil path
52
are respectively provided in the peripheral wall portion
251
of the valve body
25
at predetermined intervals.
The separating mechanism
53
controls fluid connection of the input shaft
1
and the output shaft
2
by controlling opening of the first oil paths
51
. The separating mechanism
53
is formed to include a separating member for separating the first oil paths
51
by covering openings
511
on an outer peripheral portion side of the output shaft
2
with the separating member, guide members for guiding actuation of the separating plate
531
, and a retaining member for retaining the separating member in a separating position or a canceling position. The separating member is pushed by hydraulic pressure of the first oil chamber
61
to open the first oil path
51
when the hydraulic pressure increases due to biasing of the input shaft
1
.
The separating plate
531
as the separating member is formed in a ring shape as shown in FIG.
7
and is placed on an upper face side of the peripheral wall portion
251
of the valve body
25
to thereby separate all the plurality of first oil paths
51
opening in the upper face side of the valve body
25
at once. The guide members are formed as six (a plurality of) guide pins
532
to be engaged with six (a plurality of) engaging holes
531
a
formed at predetermined intervals in a peripheral direction of the separating plate
531
so as to guide reciprocation of the separating plate
531
between a separating state and a separation canceling state. Each the guide pin
532
has a base end fixed to an upper face side of the valve body
25
and a tip end provided with a stopper
532
a
for preventing coming off of the separating plate
531
. The retaining member is formed of six (a plurality of) first magnets
533
disposed at predetermined intervals on the upper face side
2
of the valve body
25
so as to retain the separating plate
531
in the separating state and second magnets
534
disposed at the tip ends of the guide pins
532
so as to retain the separating plate
531
in the separation canceling state. The separating plate
531
is made of steel and has return pins
531
b
projecting from an upper face side of the separating plate
531
. The return pins
531
b
pushed by the intermediate plate
313
when the input shaft
1
is in the uppermost position shown in
FIG. 1
to return the separating plate
531
to the separating position.
The closing mechanism
54
is formed to include the movable pins
541
as the valve bodies for canceling connection of the second oil chamber
62
and the third oil chamber
63
to each other, pin guides
542
as guide members for supporting the movable pins
541
for upward and downward movements, and valve seats
543
for supporting the movable pins
541
in closed states. The movable pins
541
function as the valve bodies for controlling opening of the second oil paths
52
. In other fords, if the hydraulic pressure of the first oil chamber
61
increases due to biasing of the input shaft
1
, each the movable pin
541
is pushed by the hydraulic pressure to come in contact with the valve seat
543
and closes the second oil path
52
. If hydraulic pressure of the third oil chamber
63
increases or the hydraulic pressure of the first oil chamber
61
becomes negative pressure, each the movable pin
541
moves upward to open the second oil path
52
. Each the pin guide
542
is formed integrally with the vertical hole
25
b
and is provided with a return spring for moving the movable pin
541
upward if necessary. Each the valve seat
543
is formed at a step portion between the upper portion vertical hole
25
b
1
having the large inside diameter and the lower portion vertical hole
25
b
2
having the small inside diameter.
Each the movable pin
541
closes the second oil path
52
at pressure lower than pressure in the first oil chamber
61
when separation of the first oil path
51
by the separating plate is cancelled. In other words, in a process of increase of the hydraulic pressure of the first oil chamber
61
, the second oil paths
52
are first closed by the closing mechanism
54
and then separation of the first oil paths
51
by the separating mechanism
53
is cancelled. This can be achieved by setting forces of the first magnets
533
for retaining the separating plate
531
at greater values than movement resistance in closing the movable pin
541
.
As described above, because the control mechanism
5
is actuated exclusively by hydraulic pressure, it is unnecessary to especially provide an actuator as a drive source and a sensor and the like for controlling the actuator. Therefore, it is possible to dispose the large number of oil paths in limited space such as the peripheral wall portion of the valve body and oil can be moved swiftly between the respective oil chambers, which of course contributes to provision of the low-cost and less trouble-prone pressurizing apparatus with a simple structure.
The hydraulic mechanism
6
is formed to include the first piston
12
formed in the input shaft
1
, the first oil chamber
61
biased by the first piston
12
, the second oil chamber
62
communicating with the first oil chamber
61
to transmit biasing transmitted from the first oil chamber
61
to the second piston
23
, and the second piston formed in the output shaft
2
. As described already, because the pressurizing area of the second piston
23
is set to be larger than the pressurizing area of the first piston
12
, biasing by the first piston
12
is increased according to the ratio between the pressurizing areas of the first oil chamber
61
and the second oil chamber
62
by Pascal's law and transmitted to the second piston
23
. Therefore, it is possible to apply high thrust to the output shaft.
Here, actuation of the pressurizing apparatus according to the embodiment will be described in detail.
FIG. 1
shows an initial state of this pressurizing apparatus. In this state, an actuating signal is transmitted and the servomotor (not shown) rotates to normally rotate the ball screw
72
through a speed reducing mechanism (not shown). If the ball screw
72
is rotated normally, the nut
71
mounted to the ball screw
72
acts directly and downward. Because the input shaft
1
is directly connected to the nut
71
, the input shaft
1
moves down with the nut
71
. The input shaft
1
moves in such a direction as to bias the projection
411
of the lock arm
41
disposed on the input shaft
1
toward the recessed portion
42
formed in the output shaft
2
. Therefore, though the lock arm spring
43
biases in such a direction as to cancel engagement of the lock arm
41
, direct connection of the input shaft
1
and the output shaft
2
to each other is maintained and the output shaft
2
moves down with the input shaft
1
. Therefore, if a speed reducing ratio in transmitting rotation from the servomotor to the ball screw
72
is set at a small value, the output shaft
2
can be carried rapidly with low thrust but at a high speed. Until the projection
411
of the lock arm
41
disposed on the input shaft
1
is reliably engaged with the recessed portion
42
formed in the output shaft
2
, the lock arm returning roller
44
maintains the lock arm
41
in a predetermined orientation against the lock arm spring
43
. As the output shaft
2
moves downward, the valve body
25
provided to an intermediate portion of the output shaft
2
, i.e., the second piston
23
moves downward, the second oil chamber
62
is expanded, and the third oil chamber
63
is contracted. However, because the second oil chamber
62
and the third oil chamber
63
communicate with each other through the second oil paths
52
, oil moves from the third oil chamber
63
to the second oil chamber
62
without large resistance and high-speed movement of the output shaft
2
is not hindered.
If the rapid carrying of the output shaft
2
is finished as shown in
FIG. 2
, the servomotor is stopped temporarily. Then, if the biasing force from the input shaft
1
to the output shaft
2
is attenuated and the force of the lock arm
41
for pushing the projection
411
against the recessed portion
42
is attenuated, engagement by the lock arm
41
is cancelled by the lock arm spring
43
. Thus, the input shaft
1
is separated from the output shaft
2
and can move down independently.
If the input shaft
1
moves down independently as shown in
FIG. 3
, the first piston
12
biases the first oil chamber
61
and hydraulic pressure of the first oil chamber
61
increases due to this biasing. Because the separating plate
531
is attracted by the first magnets
533
, the movable pins
541
with small movement resistance are first moved by biasing of the hydraulic pressure of the first oil chamber
61
in such a direction as to close the second oil paths
52
. When the movable pins
541
come in contact with the valve seats
543
and cannot move any more, the hydraulic pressure of the first oil chamber
61
further increases, a biasing force due to the hydraulic pressure exceeds attracting forces of the first magnets
533
, and separation of the first oil paths
51
by the separating plate
521
is cancelled. The separating plate
531
is pushed by biasing until the plate
531
comes in contact with the stoppers
532
a
of the guide pins
532
and is attracted by the second magnets
524
to maintain a state in which separation of the first oil chamber
61
and the second oil chamber
62
from each other is cancelled. Thus, biasing of the first oil chamber
61
by the first piston
12
is transmitted from the second oil chamber
62
through the first oil paths
51
to the second piston
23
. Because the pressurizing area of the second oil chamber
62
is set to be larger than the pressurizing area of the first oil chamber
61
, biasing by the first piston
12
is increased and transmitted to the second piston
23
. Therefore, the output shaft
2
having the second piston
23
is pressurized with high thrust. Although the third oil chamber
62
is biased downward by movement of the output shaft
2
due to this pressurization, an amount of movement due to this biasing is absorbed by downward movement of the sub-piston
65
supported by the auxiliary spring
64
.
When a pressurizing step is finished and the servomotor stops temporarily, the sub-piston
65
is pushed by the auxiliary spring
64
and a biasing force generated by the sub-piston
65
which tries to return to an original position acts in such a direction as to cancel closing of the movable pins
541
. If the servomotor starts rotating reversely and the output shaft
2
is biased upward, pressures in the first oil chamber
61
and the second oil chamber
62
become negative pressures. As a result, the movable pins
541
are returned to positions in an initial state and the second oil chamber
62
and the third oil chamber
63
communicate with each other. Even if the first shaft
1
moves up until the upper end of the input shaft
1
comes in contact with the guide plate
27
of the output shaft
2
and the output shaft
2
starts moving upward, large resistance is not generated because the second oil chamber
62
and the third oil chamber
63
are connected. If the output shaft
2
further moves upward, the lock arm spring
43
is returned by the lock arm returning roller
44
to a position in the initial state. The return pins
531
b
provided to the upper face of the separating plate
531
come in contact with the intermediate plate
313
and the separating plate
531
is returned to the initial separating state. Thus, operation of the present pressurizing apparatus is completed.
INDUSTRIAL APPLICABILITY
As described above, the present invention relates to a pressurizing apparatus used for pressurization of a metal mold in sheet-metal presswork and the like and clamping of a metal mold in die casting, injection molding, and the like and can provide a low-cost pressurizing apparatus with high productivity by combining a direct-connecting mechanism for moving an output shaft with low thrust and at a high speed and a fluid pressure mechanism for driving the output shaft at a low speed and with high thrust with each other.
Claims
- 1. A pressurizing apparatus comprising a fixed portion, an input shaft for acting directly in an axial direction with respect to the fixed portion, an output shaft extending coaxially with the input shaft to slide with respect to said fixed portion and said input shaft, a direct-connecting mechanism for directly connecting the output shaft and said input shaft and for causing said input shaft to directly act with respect to the fixed portion to thereby rapidly carry said output shaft with respect to the fixed portion, a fluid pressure mechanism for connecting said input shaft and said output shaft in a fluid manner and for causing said input shaft to directly act with respect to said output shaft to thereby increase biasing of said input shaft by Pascal's law and transmit the biasing to said output shaft, and a control mechanism actuated by biasing applied by said input shaft to control fluid connection of said input shaft and said output shaft to each other.
- 2. The pressurizing apparatus according to claim 1, wherein said input shaft is caused to act directly by a servomotor in the axial direction with respect to said fixed portion through a rotation/direct-action converting mechanism.
- 3. The pressurizing apparatus according to claim 2, wherein said rotation/direct-action converting mechanism is a ball screw-nut mechanism and has a ball screw supported for rotation by said fixed portion and a nut fixed to said input shaft.
- 4. The pressurizing apparatus according to claim 1, wherein said fluid pressure mechanism includes a first fluid chamber biased by said input shaft by causing said input shaft to directly act with respect to said output shaft and a second fluid chamber having a larger pressurizing area than the first fluid chamber to bias said output shaft and said control mechanism opens a first fluid path between said first fluid chamber and said second fluid chamber to connect said input shaft and said output shaft in a fluid manner.
- 5. The pressurizing apparatus according to claim 4, wherein said control mechanism includes a separating mechanism disposed in said first fluid path to separate said first fluid path and to cancel said separation by pressure in said first fluid chamber increased by biasing applied by said input shaft.
- 6. The pressurizing apparatus according to claim 5, wherein said second fluid chamber has a second fluid path communicating with a third fluid chamber provided separately from said first fluid chamber and the second fluid path is open while rapid carrying by said direct-connecting mechanism is carried out and is closed by a closing mechanism actuated by said pressure of said first fluid chamber increased by said biasing by said input shaft after direct connection by said direct-connecting mechanism is cancelled.
- 7. The pressurizing apparatus according to claim 6 wherein said closing mechanism closes said second fluid path at pressure lower than pressure at which said separation by said separating mechanism is cancelled.
- 8. The pressurizing apparatus according to claim 7, wherein magnets for retaining a separating member in respective positions corresponding to a separating state and a separation canceling state of said first fluid path are disposed in said control mechanism in said separating mechanism.
- 9. The pressurizing apparatus according to claim 4, wherein said first fluid chamber is defined by an outer peripheral portion of said input shaft, a first piston provided to the outer peripheral portion, and a first cylinder formed inside said output shaft, said second fluid chamber and said third fluid chamber are defined by an outer peripheral portion of said output shaft, a second piston provided to an axial intermediate portion of the outer peripheral portion, and a second cylinder formed inside said fixed portion and are disposed on opposite sides of the second piston in an axial direction of said output shaft.
- 10. The pressurizing apparatus according to claim 9, wherein said third fluid chamber has a sub-piston moved by biasing by said output shaft to absorb said biasing of said output shaft.
- 11. The pressurizing apparatus according to claim 9, wherein said first fluid path is formed of a passage hole formed in said output shaft and connecting an outer peripheral side and an inner side of said output shaft and said second fluid path is formed of a passage hole formed in said second piston and connecting axial opposite outer faces of said second piston.
- 12. The pressurizing mechanism according to claim 1, wherein said direct-connecting mechanism is formed by disposing an engaging member in one of said input shaft and said output shaft and disposing an engaged member in the other, direct connection of said input shaft and said output shaft to each other by said engaging member and said engaged member is maintained by biasing of said output shaft by said input shaft, and said direct connection of said input shaft and said output shaft to each other is cancelled when said biasing of said output shaft by said input shaft is attenuated.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-8187 |
Jan 2001 |
JP |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/JP01/01265 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO02/05529 |
7/8/2002 |
WO |
A |
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4300351 |
Grullmeier |
Nov 1981 |
A |
4787206 |
Fabrowsky |
Nov 1988 |
A |
5345766 |
Leonhartsberger et al. |
Sep 1994 |
A |
Foreign Referenced Citations (1)
Number |
Date |
Country |
2000-141092 |
May 2000 |
JP |