JP3206889B2 - Mold clamping devices such as injection molding machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device such as an injection molding machine, and more particularly to a mold clamping device such as an injection molding machine having a pressure increasing means for increasing the pressure when closing a mold after closing the mold. Regarding improvement.

[0002]

2. Description of the Related Art Conventionally, in a mold clamping apparatus such as an injection molding machine, a movable plate is moved to open and close a mold with a fixed plate, and further, the mold is pressed against an injection resin pressure. The function of clamping the mold with a large force is required. Conventionally, as such a mold clamping device, a boost ram system in which a boost ram is inserted inside a mold ram inserted and arranged in a mold clamping cylinder, and a side cylinder system in which a plurality of side cylinders are installed separately from the mold clamping cylinder. Or a mechanism such as a pressure-intensifying cylinder system in which a mold-clamping cylinder and a pressure-intensifying cylinder are arranged in series, and configured to open and close the mold at high speed and to clamp the mold at high pressure. Direct pressure type clamping devices are widely used.

[0003] However, the conventional direct pressure type mold clamping device is required to open and close the mold at a high speed and to obtain a sufficient mold clamping force.
It is necessary to provide a complicated hydraulic circuit, and it is also necessary to provide an oil tank for storing the pressurized oil supplied to the mold-clamping cylinder, etc., especially for the boost ram system and side cylinder system described above. However, in order to obtain a high mold clamping force, it is necessary to employ a high-pressure pump, and in the case of a pressure-increasing cylinder system, there is a problem that the length of the device becomes large.

[0004] From such a viewpoint, a first and second hydraulic chambers are provided which have a volume that increases and decreases by the same amount as the double-acting ram moves, and the first and second hydraulic rams move together with the moving plate. A dynamic cylinder, a pump that is rotationally driven by a first driving device is provided in a hydraulic passage connecting the first hydraulic chamber and the second hydraulic chamber, and the pump and the first and second hydraulics are provided. A communication state interposed between the first and second hydraulic chambers and the pump through a pressure liquid passage between the first and second hydraulic chambers and a cutoff state for interrupting the communication between the first and second hydraulic chambers and the pump. And a first and second pressure-intensifying chambers whose volume increases and decreases by the same amount with the movement of the double-acting piston and communicates with the first and second hydraulic-pressure chambers, respectively. A first double-acting cylinder is provided, and a nut member and a predetermined screw structure are provided on the nut member. And a male screw member combined therewith, and one of these members is connected to the double-acting piston, and the other member is rotationally driven in both forward and reverse directions by the second driving device to reciprocate the double-acting piston. There has been proposed a mold clamping device for an injection molding machine provided with a screw mechanism for causing a screw mechanism (Japanese Patent Publication No. 1-17851).

That is, the mold clamping device having the above-described structure
The rotation of the pump in the communication state of the switching valve device activates the first double-acting cylinder to open and close the mold, while the rotation of the screw mechanism in the shut-off state of the switching valve device causes the first double-acting cylinder to rotate. Is operated to perform mold clamping.

Accordingly, the mold clamping device thus configured causes the pump to flow the pressurized liquid filled in the first and second hydraulic chambers and the pressurized liquid passage when the mold is opened and closed. Thus, since the double-acting ram is configured to move forward and backward, advantages such as no need to provide a tank or the like for storing the pressurized liquid outside can be obtained.

[0007] In addition, conventionally, there is also known a mold clamping device configured to reciprocally drive a movable plate by a screw feed mechanism driven by, for example, an AC servomotor. In this type of mold clamping device, in order to obtain sufficient mold clamping force,
It is unavoidable to increase the size of a screw feed mechanism or the like for transmitting a mold clamping force to a moving plate including a servomotor. In particular, in the case of a type in which a hydraulic device is used in combination with a servomotor, a large clamping force can be obtained, but devices such as a hydraulic pump, a hydraulic circuit, and the like are required, and there has been a problem that the device becomes complicated.

From such a viewpoint, one end of the male screw rod is screwed into the inner hole of the nut member rotated by the servomotor, and the rotation of the nut member enables the male screw rod to move straight. A hydraulic operating panel is provided adjacent to the rear part of the moving plate so as to engage with the moving plate so as to create a gap, and is guided and moved by the tie bar, and the tip of the male screw rod is engaged with the hydraulic operating panel to move. When moving the plate, moving the moving plate forward and closing the mold,
The hydraulic operating panel is provided with a hydraulic operating panel position fixing means for engaging the groove provided on the outer periphery of the tie bar to fix the hydraulic operating panel, and the hydraulic operating panel has a built-in airtight bag filled with liquid. A piston is provided for generating a mold clamping force on the moving plate by being displaced by increasing the pressure of the sealed liquid in the sealed bag, and by advancing the male screw rod after the hydraulic operating panel is fixed to the tie bar,
There has been proposed a mold clamping device for an injection molding machine having a structure in which a cushioning member is provided so that the sealing bag is pressed by a male screw rod to apply a clamping force to a piston (Japanese Patent Laid-Open No. 6-24).
No. 6806).

That is, the mold clamping device having the above configuration is
The sealed liquid in the sealed bag is pressed and compressed by the male screw rod, and the pressure of the sealed liquid that is increased by this is used as a mold clamping force. It is sufficient to apply a slight pressing force to the sealed liquid. This is advantageous in that a tightening force can be obtained, and a servomotor as a drive source and a screw feed mechanism for transmitting the force of the servomotor can be miniaturized.

[0010]

However, the pressure increasing mechanism in the mold clamping device of the conventional injection molding machine has the following disadvantages to be improved.

That is, the former pressure-increasing mechanism of the mold clamping device, which is configured to operate the double-acting cylinder by the rotation of the screw mechanism to open and close the mold and to clamp the mold, together with the movement of the double-acting ram. Two fluid pressure chambers whose volume increases and decreases by the same amount are provided. Two more pressure boosting chambers are further provided, and the mold is opened and closed by the flow of the pressurized fluid by the pump by switching the switching valve. At the same time, the mold is clamped by the rotation of the screw mechanism, which complicates the configuration and control operation, increases the manufacturing cost, and also has the disadvantage of causing leakage of pressure fluid, generation of noise, and the like.

[0012] Further, a mold clamping device is configured to generate a mold clamping force by increasing the pressure of the sealed liquid in the sealed bag by pressing and displacing the sealed bag filled with the liquid by the latter hydraulic operating panel. Although the pressure boosting mechanism has the advantage of contributing to the miniaturization of the device, it has many restrictions on the production of a sealed bag filled with liquid and the production of a displacement transmission mechanism for obtaining a sufficient pressing force. And the manufacturing cost increases.

Accordingly, an object of the present invention is to provide a simple and compact structure, to prevent the occurrence of liquid leakage and noise, and to achieve a complex mold closing and clamping operation smoothly. An object of the present invention is to provide a mold clamping device such as an injection molding machine capable of performing efficient injection molding and the like.

[0014]

In order to achieve the above object, a mold clamping apparatus such as an injection molding machine according to the present invention mounts a movable mold via a tie bar on a fixed plate on which a fixed mold is mounted. The moving plate is disposed so as to be capable of moving forward and backward, and a connecting plate provided with pressure increasing means is provided behind the moving plate via a tie bar, and moving means for moving the connecting plate and the moving plate forward and backward on the tie bar. In a mold clamping device such as an injection molding machine provided with engaging means for locking the movement at a predetermined position, the pressure increasing means includes a piston portion of a piston rod in a cylinder liquid chamber of a closed hydraulic cylinder. It is housed in a closed manner, and a pressure increasing control unit disposed adjacent to the cylinder liquid chamber controls the liquid pressure in the cylinder liquid chamber to obtain a mold clamping force increased from the piston rod. Further liquid passage communicating with the cylinder liquid chamber and the pressure increase control section provided, characterized in that it placed through a compression member configured to be moved forward and backward by the servo motor to the fluid passage.

In this case, the moving means for moving the connecting plate and the moving plate forward and backward on the tie bar is provided on the connecting plate or the moving plate with respect to the screw portion of the drive shaft which is rotationally driven by the servomotor fixed to the fixed plate. Can be configured by screwing a nut member fixed to the nut.

An engaging means for locking the connecting plate and the moving plate on the tie bar at a predetermined position on the tie bar includes: a sealing casing having a pressure oil inlet / outlet at a penetrating portion of the tie bar in the connecting plate;
An elastic tightening sleeve having a spiral groove formed in the sealed casing so as to engage with the outer peripheral surface of the tie bar.

Further, the fluid passage for communicating the cylinder fluid chamber and the pressure increasing control unit in the pressure increasing means communicates with the fluid passage arranged in parallel with the axis of the piston rod so as to intersect perpendicularly with the fluid passage. It is possible to adopt a configuration in which a compression member which is composed of an orthogonal liquid passage and which is configured to be able to move forward and backward by a servomotor with respect to the orthogonal liquid passage is inserted.

The engaging means is provided with a compression member which is configured to be able to move forward and backward by a servomotor with respect to the only pressure oil inlet / outlet formed in the sealed casing, and is a feed screw which moves the compression member forward and backward by rotational driving. At the same time, the feed screw can be screwed and held by a rotary nut, and the rotary nut can be connected to the output shaft of the servomotor via a connecting portion.

Further, according to the present invention, the moving means for moving the connecting plate and the moving plate forward and backward on the tie bar can be constituted by a toggle link mechanism provided between the connecting plate and the moving plate.

In this case, the pressure-increasing means may be built in the movable plate, and may be configured to couple the toggle link mechanism to a piston rod provided in the closed hydraulic cylinder.

As described above, according to the present invention, the means for engaging the connecting plate or the moving plate with the tie bar and the means for increasing the pressure applied to the moving plate, which are disadvantageous in the conventional mold clamping device of this type, are used. By using independent drive system using servo motors,
To quickly and reliably perform the mold closing operation to eliminate the loss time in the molding cycle, and to achieve the mold clamping force in the mold clamping operation smoothly with a simple and small device configuration without generating oil leakage or noise. Can be.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a mold clamping apparatus such as an injection molding machine according to the present invention.

Embodiment 1 FIGS. 1 to 3 show an embodiment of a mold clamping apparatus such as an injection molding machine according to the present invention. 1 to 3, the mold clamping device of the present embodiment basically includes a movable plate 18 having a movable mold 16 attached via a tie bar 14 to a fixed plate 12 having a fixed mold 10 attached.
Are arranged so as to be able to move forward and backward, and a connecting plate 20 is arranged behind the moving plate 18 via a tie bar 14, and a pressure increasing means 22 is mounted between the moving plate 18 and the connecting plate 20. Consists of

The connecting plate 20 is a fixed plate 1
2 is coupled via a nut member 28 to a screw portion 26a of a drive shaft 26 which is rotationally driven by a servo motor 24 as a moving means fixed to 2, and is rotated by the drive shaft 26 so that the screw portion 26a is Together with the threaded nut member 28, it is configured to be able to advance and retreat along the axial direction of the tie bar 14. Also, the nut member 28
The moving plate 18 may be provided.

Further, the connecting plate 20 is disposed so as to be movable and locked to the tie bar 14 via an engaging means 30 shown in an enlarged manner in FIG. In FIG. 1, reference numeral 32 indicates a nozzle portion of the injection molding machine.

However, in FIG.
Is the through portion 3 of the tie bar 14 in the connection plate 20.
4, a sealed casing 38 having a pressure oil port 36,
An elastic tightening sleeve 42 having a spiral groove 40 formed in the sealed casing 38 so as to engage with the outer peripheral surface of the tie bar 14. In the illustrated embodiment, the sealed casing 38 and the elastic fastening sleeve 42 are integrally formed of the same material, but may be formed by combining materials formed of different materials. .

When the pressurized oil is not introduced from the pressurized oil inlet / outlet 36 into the sealed casing 38, the elastic fastening sleeve 42 is contracted inward and the tie bar 14 can be restrained in an interference fit. When the pressurized oil is introduced from the pressurized oil inlet / outlet 36 into the inside of the sealed casing 38, the elastic tightening sleeve 42 expands outward and the tie bar 14
Is slidably opened. In this manner, the engagement means 30 can move or lock the connection plate 20 with respect to the tie bar 14.

On the other hand, in this embodiment, the pressure increasing means 2
2 is configured as shown in FIG. That is, in FIG. 3, the pressure increasing means 22 includes a closed hydraulic cylinder 44 and a pressure increasing control section 46, and the piston section 50 of the piston rod 50 is provided in a cylinder liquid chamber 48 of the closed hydraulic cylinder 44.
a is housed in a closed state, and the pressure in the cylinder liquid chamber 48 is controlled by a pressure increase control unit 46 disposed adjacent to the cylinder liquid chamber 48 so as to obtain an increased pressure output from the piston rod 50. Have been. Accordingly, the piston rod 50 is connected to the moving plate 18 of the mold clamping device.

In this embodiment, the pressure increasing means 22 is attached to the connecting plate 20. However, the closed hydraulic cylinder 44 and the connecting plate 20 or the piston rod 50 and the moving plate 18 are integrated to form the connecting plate 20. You may comprise so that the pressure increasing means 22 may be built in.

However, the communication part between the cylinder liquid chamber 48 and the pressure increasing control part 46 has a liquid passage 52 arranged coaxially with the axis of the piston rod 50, and an orthogonal liquid communicating perpendicularly to and communicating with the liquid passage 52. A compression member 56 which is configured to be able to advance and retreat by a servomotor 54 is inserted into the orthogonal liquid passage 53 and disposed therein. In this case, the compression member 56 is coaxially coupled with a feed screw 58 that moves forward and backward by rotational driving, and the feed screw 58 is connected to a rotary nut 60 that screws and holds the feed screw 58 through a connecting portion 62. It is configured to be coupled to the output shaft 55 of the servo motor 54. In the connecting portion 62, a spline groove is formed in the feed screw 58 and the output shaft 55, and the spline groove is engaged with the spline groove to transmit a rotational force to the feed screw 58. further,
The feed screw 58 moves forward and backward in cooperation with the rotary nut 60.

Further, in the cylinder liquid chamber 48,
A back pressure part liquid passage 64 is provided in a part of the closed hydraulic cylinder 44 on the back pressure side of the piston part 50a, and the pressure liquid is introduced to the back pressure side when the mold is opened. In FIG. 3, reference numeral 66 denotes a seal member formed of an O-ring or the like provided at an appropriate position to hold the cylinder liquid 48 in a liquid-tight manner.

In this embodiment, the liquid passage 52 is arranged coaxially with the axis of the piston rod 50. However, since the pressure-increasing output is obtained evenly over the entire piston rod 50, the liquid passage 52 is parallel to the axis without any problem. Can be arranged at various positions.

In the thus-configured mold clamping apparatus of the present embodiment, the moving plate 18 is moved forward together with the connecting plate 20 with respect to the fixed plate 12 by the moving means including the servomotor 24 to close the mold. By drawing out the pressure oil from the pressure oil inlet / outlet 36 formed in the sealed casing 38 of the engagement means 30 in the closing limit, the elastic tightening sleeve 42 and the tie bar 14 are properly locked. At the same time, by driving the pressure increasing control unit 46 of the pressure increasing means 22, that is, the servo motor 54, the piston rod 50 of the closed hydraulic cylinder 44 is moved forward to smoothly perform the mold clamping operation by the movable plate 18. be able to.

Therefore, according to the thus-configured mold clamping apparatus of the present embodiment, in the mold closing operation, the engagement of the connecting plate 20 and the moving plate 18 to the tie bar 14 is quickly performed by the engagement means 30. In addition, in the mold clamping operation, the pressure increasing control section 46 of the pressure increasing means 22 is easily sealed by the sealing member 66 by the drive of the dedicated servomotor 54, and the sealing liquid having the independent structure is provided. With the piston rod 50 composed of the pressure cylinder 44, a stable mold clamping force can always be obtained, the configuration is simple and small, the degree of freedom in design such as shape and capacity is expanded, and leakage of pressure liquid is caused. Noise and noise can be suppressed as much as possible.

Embodiment 2 FIG. 4 shows another embodiment of the engaging means 30 in the above embodiment. That is, in the present embodiment, in the configuration of the engagement means 30 shown in FIG. 2 described above, the engagement control unit 70 provided with the dedicated servomotor 72 for the only pressure oil port 36 formed in the sealed casing 38. Is provided. The other configuration is the same as the configuration shown in FIG. 2 described above, and thus the same components will be denoted by the same reference characters and detailed description thereof will be omitted.

However, the engagement control unit 7 in the present embodiment
The configuration of 0 is basically the same as the configuration of the pressure increasing control section 46 employed in the pressure increasing means 22 of the above embodiment. That is,
In this embodiment, the compression member 7 is configured to be able to advance and retreat with the servomotor 72 with respect to the pressure oil port 36.
4 is inserted and arranged. In this case, the compression member 74 is coaxially coupled to a feed screw 76 that moves forward and backward by rotational driving, and the feed screw 76 connects a rotation nut 78 that screwably holds the feed screw 76 through a connection portion 80. The servo motor 72 is connected to the output shaft 73.

As described above, by configuring the engaging means 30, the movement or locking control of the connecting plate 20 with respect to the tie bar 14 can be easily and quickly achieved.

Embodiment 3 FIG. 5 shows another embodiment of the pressure increasing means 22 in the above embodiment. That is, in the present embodiment, the configuration of the piston rod 50 in the cylinder liquid chamber 48 of the closed hydraulic cylinder 44 is modified in the configuration of the pressure increasing means 22 shown in FIG. Therefore, FIG.
The same reference numerals are given to the same components as the components shown in (1), and the detailed description is omitted.

However, the pressure increasing means 22 in the present embodiment
Is a communication hole 6 that communicates with the piston portion 50a of the piston rod 50 between the pressure increasing chamber side and the back pressure chamber side of the cylinder liquid chamber 48.
8 is provided. With such a configuration, it is possible to exhibit the same pressure increasing effect at the time of the mold clamping operation as in the embodiment shown in FIG.

Embodiment 4 FIGS. 6 and 7 show still another embodiment of a mold clamping device such as an injection molding machine according to the present invention. In this embodiment, a toggle link mechanism 82 is employed as a moving means of the moving plate 18. For convenience of explanation, the same components as those in the embodiment shown in FIGS. 1 and 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in FIG. 6, the mold clamping device of the injection molding machine according to the present embodiment fixes the connecting plate 20 to the tie bar 14 and fixes the moving plate 18 between the connecting plate 20 and the moving plate 18. As a means of transportation
A toggle link mechanism 82 is provided. However,
The link drive control unit 84 of the toggle link mechanism 82
It is configured to be attached to the connection plate 20. The link drive control unit 84 is configured by connecting a nut member 88 configured to be able to move forward and backward by a servo motor 86 to a part of the toggle link mechanism 82. In this case, the nut member 88 is configured to advance and retreat by being screwed into a rotationally driven screw shaft 90, and the screw shaft 90 is connected to an output shaft 87 of the servomotor 86 via a connecting portion 92. It consists of a configuration.

On the other hand, the moving plate 18 to which the toggle link mechanism 82 is connected has a built-in pressure increasing means 94. That is, the pressure increasing means 94 in the present embodiment
The toggle link mechanism 82 is configured to be connected to a piston rod 100 provided in the closed hydraulic cylinder section 96, comprising a closed hydraulic cylinder section 96 and a pressure increase control section 98. However, the structure of the pressure increasing means 94 in this embodiment is as shown in FIG. 7, and the detailed structure is the same as that of the pressure increasing means 22 shown in FIG. The relative positions of the chamber 48 and the piston rod 100 are different. Note that the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the mold clamping apparatus of this embodiment having the above-described structure, the mold closing operation and the mold clamping operation can be performed basically in the same manner as in the embodiment shown in FIGS. The same effects as in the above embodiment can be obtained.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and many modifications can be made without departing from the spirit of the present invention. That is, it goes without saying that the mold clamping device of the present invention can be similarly applied to, for example, a mold clamping device of a die casting machine.

[0045]

As described above, the mold clamping device such as the injection molding machine according to the present invention moves the movable plate with the movable mold attached thereto via the tie bar with respect to the fixed plate with the fixed mold attached. A connecting plate which is disposed so as to be capable of retreating and is provided with a pressure increasing means via a tie bar behind the moving plate, and a moving means for moving the connecting plate and the moving plate forward and backward on the tie bar and moving the moving plate at a predetermined position In a mold clamping device such as an injection molding machine provided with engaging means for locking in, the pressure increasing means hermetically accommodates the piston portion of the piston rod in the cylinder fluid chamber of the closed hydraulic cylinder, The hydraulic pressure in the cylinder liquid chamber is controlled by a pressure increase control unit disposed adjacent to the cylinder liquid chamber to obtain an increased mold clamping force from a piston rod. A liquid passage communicating the liquid chamber and the pressure increasing control section is provided, and a compression member configured to be able to move forward and backward by a servomotor is inserted through the liquid passage so that the mold closing operation can be performed quickly and reliably. By doing so, the loss time in the molding cycle can be eliminated, and the mold clamping force in the mold clamping operation can be smoothly achieved by a simple and compact device configuration without generating oil leakage, noise, and the like. Furthermore, according to the present invention, a complex mold closing and mold clamping operation can be smoothly achieved, and efficient injection molding and the like can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of a mold clamping device such as an injection molding machine according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of an engaging means in the mold clamping device shown in FIG.

FIG. 3 is an enlarged sectional view of a main part showing a pressure increasing means in the mold clamping device shown in FIG. 1;

FIG. 4 is an enlarged sectional view of a main part showing another embodiment of an engaging means in a mold clamping device such as an injection molding machine according to the present invention.

FIG. 5 is an enlarged sectional view of an essential part showing another embodiment of a pressure increasing means in a mold clamping device such as an injection molding machine according to the present invention.

FIG. 6 is a schematic partial cross-sectional side view showing still another embodiment of a mold clamping device such as an injection molding machine according to the present invention.

FIG. 7 is an enlarged sectional view of a main part showing a pressure increasing means in the mold clamping device shown in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixed die 12 Fixed plate 14 Tie bar 16 Moving die 18 Moving plate 20 Connecting plate 22 Pressure increasing means 24 Servo motor 26 Drive shaft 26a Screw part 28 Nut member 30 Engaging means 32 Nozzle part 34 of injection molding machine 34 Penetrating part 36 Pressure oil inlet / outlet 38 Sealed casing 40 Spiral groove 42 Elastic tightening sleeve 44 Closed hydraulic cylinder 46 Pressure increase control unit 48 Cylinder liquid chamber 50 Piston rod 50a Piston part 52 Liquid passage 53 Orthogonal liquid passage 54 Servo motor 55 Output shaft 56 Compression member 58 Feed screw 60 Rotating nut 62 Connecting part 64 Back pressure part liquid passage 66 Seal member 68 Communication hole 70 Engagement control part 72 Servo motor 73 Output shaft 74 Compression member 76 Feed screw 78 Rotating nut 80 Connecting part 82 Toggle link mechanism 84 Link drive Control unit 6 servo motor 87 output shaft 88 a nut member 90 threaded shaft 92 connecting portion 94 pressure boosting means 96 closed hydraulic cylinder 98 pressure increasing control section 100 piston rod

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yutaka Owashi 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Co., Ltd. Numazu Office (56) References JP-A-61-237617 (JP, A) JP-A-63 −212524 (JP, A) Hikaru 1-145411 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/67-45/76 B22D 17/02-17/26 B29C 33/02-33/36

Claims (7)

(57) [Claims] 1. A moving plate on which a moving mold is mounted is opposed to a fixed plate on which a fixed mold is mounted via a tie bar so as to be able to move forward and backward, and a pressure increasing means is provided behind the moving plate via a tie bar. An injection molding machine or the like, which includes a connecting plate provided with a moving means for moving the connecting plate and the moving plate forward and backward on the tie bar, and an engaging means for locking the movement at a predetermined position. In the mold clamping device, the pressure increasing means hermetically accommodates the piston portion of the piston rod in the cylinder liquid chamber of the closed hydraulic cylinder, and controls the hydraulic pressure in the cylinder liquid chamber by a pressure increasing control unit disposed adjacent to the cylinder liquid chamber. To increase the clamping force from the piston rod, and further provide a liquid passage communicating the cylinder liquid chamber with the pressure increase control unit. Mold clamping apparatus, such as an injection molding machine, characterized in that the inserted position the compression member configured to be moved forward and backward by Bomota. 2. A moving means for moving the connecting plate and the moving plate forward and backward on the tie bar, wherein the moving means is fixed to the connecting plate or the moving plate with respect to a screw portion of a drive shaft which is rotationally driven by a servomotor fixed to the fixed plate. The mold clamping device of an injection molding machine or the like according to claim 1, wherein the nut member is formed by screwing and coupling. 3. An engagement means for locking the connection plate and the moving plate on the tie bar at a predetermined position on the tie bar, the sealing plate having a pressurized oil port at a penetrating portion of the tie bar in the connection plate; 2. A mold clamping device for an injection molding machine or the like according to claim 1, further comprising an elastic clamping sleeve having a spiral groove formed in said sealed casing so as to engage with an outer peripheral surface of the tie bar. 4. A liquid passage communicating between the cylinder liquid chamber and the pressure increase control unit in the pressure increasing means is a liquid passage arranged in parallel with the axis of the piston rod, and an orthogonally perpendicularly intersecting and communicating with the liquid passage. 2. The mold clamping device for an injection molding machine or the like according to claim 1, wherein a compression member comprising a liquid passage, the compression member being configured to be able to advance and retreat by a servomotor with respect to the orthogonal liquid passage is inserted and arranged. 5. A compression member configured to be able to move forward and backward by a servo motor is inserted through the only pressure oil inlet / outlet formed in the sealed casing, and the compression member is coupled simultaneously with a feed screw that moves forward and backward by rotational driving. 4. The mold clamping device for an injection molding machine or the like according to claim 3, wherein said feed screw is screwed and held by a rotary nut, and said rotary nut is connected to an output shaft of said servomotor via a connecting portion. 6. The injection molding machine according to claim 1, wherein the moving means for moving the connecting plate and the moving plate forward and backward on the tie bar comprises a toggle link mechanism provided between the connecting plate and the moving plate. Mold clamping device. 7. The injection molding machine according to claim 6, wherein the pressure increasing means is built in the moving plate, and is configured to couple the toggle link mechanism to a piston rod provided in the closed hydraulic cylinder portion. Mold clamping device.