JP3401446B2 - 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 an improvement of a mold clamping device such as an injection molding machine provided with a pressure increasing means for increasing pressure when the mold is clamped after the mold is closed. Regarding

[0002]

2. Description of the Related Art In a conventional mold clamping device such as an injection molding machine, a movable plate is moved to open and close the mold with a fixed plate, and the mold is further resisted against injection resin pressure. It is required to have a function of clamping with a large force. As such a mold clamping device, conventionally, there is a boost ram system in which a boost ram is inserted inside a mold clamping ram inserted through a mold clamping cylinder, and a side cylinder system in which a plurality of side cylinders are installed separately from the mold clamping cylinder. Alternatively, it is a mechanism such as a pressure-increasing cylinder system in which a mold-clamping cylinder and a pressure-increasing 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 mold clamping devices are widely used.

However, in the conventional direct pressure type mold clamping device, in order to open and close the mold at a high speed and 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, etc. for storing the pressure oil to be supplied to the mold clamping cylinder, etc., especially for the boost ram system and side cylinder system described above. In order to obtain a high mold clamping force, it is necessary to adopt a high pressure pump, and in the pressure boosting cylinder type, there is a problem that the length dimension of the apparatus becomes large.

From such a point of view, there has been proposed a pressure increasing mechanism of a mold clamping device configured to operate a double-acting cylinder by rotation of a screw mechanism to open and close a mold and perform mold clamping. The pressure increasing mechanism of the kind is provided with two hydraulic chambers whose volumes increase and decrease by the same amount as the double-acting ram moves, and further by providing two pressure increasing chambers and switching operation of the switching valve. , The mold is opened and closed by the flow of the pressure liquid by the pump, and the mold is clamped by the rotation of the screw mechanism, which complicates the configuration and the control operation.
Not only does the manufacturing cost increase, but it also has the drawback of causing leakage of pressure fluid and noise.

Further, conventionally, there is also known a mold clamping device configured to reciprocally drive a moving plate by a screw feed mechanism driven by an AC servomotor, for example. In this type of mold clamping device, in order to obtain a sufficient mold clamping force,
Increasing the size of the screw feed mechanism for transmitting the mold clamping force to the moving plate, including the servo motor, is inevitable.

From this point of view, therefore, a mold configured to generate a mold clamping force by pressurizing and displacing the sealed bag in which the liquid is sealed by the hydraulic pressure plate by increasing the pressure of the sealed liquid in the sealed bag. Although a pressure increasing mechanism for a tightening device has been proposed, this type of pressure increasing mechanism has an advantage of contributing to downsizing of the device, but it is necessary to manufacture a sealed bag in which liquid is sealed and to obtain sufficient pressing force. When manufacturing the displacement transmitting mechanism, there are many restrictions, and it takes time and effort to manufacture the displacement transmitting mechanism, and the manufacturing cost also increases.

[0007] Therefore, the applicant of the present invention can be easily and compactly constructed, can prevent liquid leakage and noise, and can smoothly achieve complex mold closing and mold clamping operations. Developed a mold clamping device such as an injection molding machine that can perform efficient injection molding.
No. 7028 (Japanese Patent Laid-Open No. 10-258450).

That is, the mold clamping device such as the injection molding machine according to this proposal is different from the fixed plate on which the fixed mold is attached.
A moving plate attached with a moving die via a tie bar is arranged so as to be able to move forward and backward, and a connecting plate provided with a pressure increasing means is arranged behind this moving plate via a tie bar. In a mold clamping device such as an injection molding machine, which is provided with a moving means for moving the tie bar forward and backward and an engaging means for locking the movement at a predetermined position, the pressure increasing means is a closed hydraulic cylinder. The piston portion of the piston rod is hermetically housed in the cylinder fluid chamber of, and the mold clamping force increased from the piston rod by controlling the fluid pressure in the cylinder fluid chamber by the pressure boosting control unit arranged adjacent to the cylinder fluid chamber. To get
Further, a liquid passage that connects the cylinder liquid chamber and the pressure increasing control unit is provided, and a compression member configured to be movable back and forth by a servomotor is inserted and arranged in the liquid passage.

As described above, in the mold clamping device such as the injection molding machine according to the above-mentioned proposal, the engaging means for the tie bar of the connecting plate or the moving plate, which has been a problem in the conventional mold clamping device of this type, and The pressure boosting means loaded on the moving plate is an independent drive system that uses a servo motor, so that the mold closing operation can be performed quickly and reliably to eliminate the loss time in the molding cycle, and the mold clamping operation in the mold clamping operation. The force can be smoothly achieved by a simple and small device configuration without causing oil leakage, noise, and the like.

[0010]

However, in the mold clamping device such as the conventional injection molding machine, the mold thickness adjusting operation,
In the case where the mold opening / closing operation and the pressure increasing operation are sequentially performed, when the pressure increasing means is incorporated into the mold clamping device, the structure becomes complicated and the manufacturing process is troublesome. There were problems to be solved, such as an increase in size as a whole and an increase in manufacturing cost.

Therefore, as a result of intensive studies and studies, the present inventors have made it possible to move a movable die plate, to which a movable die is attached, through a tie bar to a fixed die plate to which a fixed die is attached. A mold clamping mechanism, which is arranged facing each other and provided with a pressure increasing means via a tie bar behind the movable die plate, is arranged to move the mold clamping mechanism and the movable die plate forward and backward on the tie bar and the movement thereof. In a mold clamping device such as an injection molding machine provided with engaging means for locking at a position, the mold clamping mechanism includes a mold clamping cylinder for operating a mold clamping ram coupled to a movable die plate. It is composed of a clamping block, a servomotor moving means for mold opening and closing is connected to this clamping block, and a pressure increasing cylinder is provided coaxially with the inside of the mold clamping ram. One end of a piston rod inserted through the die is connected to the outer surface of the mold clamping block so as to move back and forth relatively by a required driving means, and further, each oil chamber of the pressure boosting cylinder and each oil chamber of the mold clamping cylinder are connected. By providing a hydraulic circuit with a switching valve that communicates with each other and selectively communicates one or both of the oil chambers of the mold clamping cylinder with the block or tank, it is possible to perform the mold thickness adjusting operation, the mold releasing operation, and the boosting operation. You can make full use of each function,
It was found that a mold clamping device such as an injection molding machine capable of smoothly performing a simple and quick mold opening / closing and a mold clamping operation and performing efficient injection molding can be obtained.

Therefore, an object of the present invention is to allow the pressure increasing means to be easily and easily incorporated, and to smoothly achieve complex mold closing and mold clamping operations for efficient injection molding and the like. An object of the present invention is to provide a mold clamping device such as an injection molding machine.

[0013]

In order to achieve the above object, a mold clamping device such as an injection molding machine according to the present invention includes a movable die through a tie bar with respect to a fixed die plate to which a fixed die is attached. The mounted movable die plates are arranged to face each other so as to move forward and backward, and a mold clamping mechanism provided with a pressure increasing means via a tie bar is arranged behind the movable die plate, and the mold clamping mechanism and the movable die plate are placed on the tie bar. In a mold clamping device such as an injection molding machine provided with a moving means for advancing and retracting and an engaging means for locking the movement at a predetermined position, the mold clamping mechanism includes a mold clamping ram connected to a movable die plate. It is composed of a mold clamping block with a mold clamping cylinder for activating a mold clamping cylinder, and a servomotor moving means for mold opening and closing is coupled to this mold clamping block, and a booster cylinder is provided inside the mold clamping ram coaxially therewith. , One end of a piston rod inserted through the pressure boosting cylinder is connected to the outer surface of the mold clamping block so as to move back and forth relatively by a required driving means, and further, it is connected to each oil chamber of the pressure boosting cylinder and the mold clamping. A hydraulic circuit is provided, which includes a switching valve that communicates with each oil chamber of the cylinder and selectively communicates one or both of the oil chambers of the mold clamping cylinder with the block or the tank.

In this case, one end of the piston rod inserted through the booster cylinder is fixed to a connecting plate connected to a ball nut screwed to a ball screw shaft rotatably connected to the outer surface of the mold clamping block. A mold clamping servomotor driving means may be coupled to one end of the ball screw shaft to move the connecting plate forward and backward along the ball screw shaft.

The retreat side oil chamber defined by the mold clamping ram of the mold clamping cylinder is connected to the forward side oil chamber defined by the piston of the pressure boosting cylinder and a passage provided in the mold clamping ram. The forward side oil chamber of the mold clamping cylinder communicates with the reverse side oil chamber of the pressure boosting cylinder via a passage and an opening / closing valve provided in the mold clamping ram. The chamber and the retreat side oil chamber may be configured to selectively communicate one or both of the oil chamber with the block or tank via a switching valve.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a mold clamping device such as an injection molding machine according to the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show one embodiment of a mold clamping device such as an injection molding machine according to the present invention.

However, in FIG. 1 and FIG. 2, the mold clamping device of this embodiment basically attaches the movable die 16 via the tie bar 14 to the fixed die plate 12 to which the fixed die 10 is attached. The movable die plate 18 is arranged so as to be able to move forward and backward, and the mold clamping block 20 is disposed behind the movable die plate 18 via the tie bar 14, and between the movable die plate 18 and the mold clamping block 20. , And a mold clamping ram 24 incorporating a pressure increasing cylinder 22 as a pressure increasing means. In this case, the mold clamping block 20 has a structure in which a mold clamping cylinder 21 for pressing and displacing the mold clamping ram 24 is incorporated.

The tie bar 14 has one end fixed to the fixed die plate 12 and the other end having a threaded portion 14a formed on the outer periphery thereof to penetrate the movable die plate 18 and the mold clamping block 20. It is configured to mesh with a half nut 26 attached to the outer surface of the tightening block 20. It should be noted that the half nut 26 is configured to perform engagement and its releasing operation by driving an actuator 28 such as a ball screw drive type servo motor or a pneumatic cylinder.

A mold opening / closing servomotor 30 is attached to the fixed die plate 12, and one end of a ball screw shaft 32 is coupled to an output shaft 30a of the servomotor 30 via a coupling 31. The other end is screwed into a ball nut 33 attached to the mold clamping block 20. Therefore, the mold clamping block 20 moves forward and backward by the rotation of the ball screw shaft 32 driven by the mold opening / closing servomotor 30.

However, a piston rod 36 having a piston 34 is inserted through the pressure increasing cylinder 22 built in the mold clamping ram 24, and one end of the piston rod 36 penetrates the mold clamping cylinder 21 in a liquid-tight manner. Then, the mold clamping block 20 is projected to the outer side surface. In addition, the mold clamping block 2
Ball screw shafts 38, 38 extending parallel to the piston rod 36 are rotatably attached to the outer surface of the ball rod 0, and ball nuts 40, 38 are attached to the ball screw shafts 38, 38.
A connecting plate 41 configured to be screwed through 40 to move forward and backward is provided, and the distal end portion 36a of the piston rod 36 is coupled and fixed to the connecting plate 41. Further, the tip ends of the ball screw shafts 38, 38 are pivotally held by a mounting plate 42, and pulleys 43, 43 are connected to the tip ends of the ball screw shafts 38, 38. And these pulleys 4
A belt 46 is wound around a drive pulley 45 of a mold clamping servomotor 44 fixed to a part of the mounting plate 42, so that the components 3 and 43 are rotatably driven. Therefore, the pressure increase control of the pressure increase cylinder 22 is performed by the mold clamping servomotor 4
By the rotation of the ball screw shafts 38, 38 driven by 4,
The connecting plate 41 moves back and forth, and together with this, the piston rod 3
This can be done by moving 6 forwards and backwards. In FIG. 1, the rightward movement is forward and the leftward movement is backward.

Next, the hydraulic circuit of the mold clamping cylinder 21 and the pressure boosting cylinder 22 will be described. Reference numeral 48 designates a first switching valve for performing three-position switching for boosting / opening switching, and 50 designates a second switching valve for low speed advance / low pressure die clamping. Therefore, the retreat side oil chamber 21 of the mold clamping cylinder 21.
B communicates with the forward oil chamber 22A of the pressure boosting cylinder 22 through a passage 24a provided in the mold clamping ram 24, and the backward oil chamber 22B of the pressure boosting cylinder 22 passes through a second switching valve 50. The mold clamping cylinder 21 communicates with the advancing side oil chamber 21A. Reference numerals 24b and 24c are provided on the mold clamping ram 24 that communicates the second switching valve 50 with the retreating oil chamber 22B of the pressure increasing cylinder 22 and the advancing oil chamber 21A of the mold clamping cylinder 21, respectively. Indicates a passage.

Further, the advancing side oil chamber 21A and the retreating side oil chamber 21B of the mold clamping cylinder 21 communicate with the tank 52 via the first switching valve 48. Therefore, when the first switching valve 48 is switched to the side a, the retreating side oil chamber 21B of the mold clamping cylinder 21 communicates with the tank 52 and the advancing side oil chamber 21.
A is blocked. In addition, the first switching valve 48,
When switched to the b side, the forward side oil chamber 21A of the mold clamping cylinder 21
Is communicated with the tank 52, and the retreating side oil chamber 21B is blocked. At the neutral position of the first switching valve 48,
The forward side oil chamber 21A and the backward side oil chamber 21B are configured to communicate with each other and to the tank 52.

Next, with respect to the operation of the mold clamping device having the above-described structure, refer to the operating states of the respective components of the mold clamping device shown in FIGS. 3 to 7 and the time chart diagram shown in FIG. While explaining.

[0025]Mold thickness adjustment operation The mold clamping block 2 is driven by driving the mold opening / closing servomotor 30.
0 and the moving die plate 18 are advanced,
1, the connecting plate 41, the piston rod 36 and the
And the mold clamping ram 24 is in the retracted position, and the second switching valve 50
Is in a non-excited position.

Further, the first switching valve 48 is in the neutral position, and the advancing side oil chamber 21A and the retreating side oil chamber 21B of the mold clamping cylinder 21 communicate with the tank 52, and there is no load. In this state, by driving the mold opening / closing servomotor 30 to rotate the ball screw shaft 32, the mold clamping block 20
The mold clamping block 20 and the moving die plate 18 are advanced at a low speed along the ball screw shaft 32 screwed into the ball nut 33 attached to the. And the moving mold 1
At the position where 6 contacts the fixed mold 10, the driving of the mold opening / closing servomotor 30 is stopped.

Next, the mold clamping servomotor 44 is driven to rotate the ball screw shafts 38, 38, and the connecting plate 41 is moved forward (moved to the right in the drawing), whereby the piston rod of the pressure boosting cylinder 22 is moved. 36 is advanced and the piston 3
4 is brought into contact with the right end wall surface of the retreating side oil chamber 22B of the pressure boosting cylinder 22, and the mold clamping block 20 is advanced.

At this time, the mold opening / closing servomotor 30 moves the ball screw shaft 3 according to the forward movement of the mold clamping block 20.
2 is driven to rotate. Further, the actuator 28 for driving the half nut 26 is also operated so that the tie bar 14 and the mold clamping block 20 can be engaged with each other.
When is engaged with the screw portion 14a of the tie bar 14, the driving of the mold opening / closing servomotor 30 is stopped, and the driving of the mold clamping servomotor 44 is also stopped. Then, the half nut 26 is engaged with the screw portion 14a of the tie bar 14 by the operation of the drive actuator 28, and the mold thickness adjusting operation is completed.

The stop positions by these servo motors are
The half nut 26 and the tie bar 14 are stored in the storage device.
It is set as a meshing position with the screw portion 14a. In this way, adjustment of the mold thickness can be easily achieved.

When the mold closing operation is performed, the required low-speed movement amount is determined, the required meshing position between the half nut 26 and the screw portion 14a of the tie bar 14 is calculated from the mold thickness, and the calculated result is obtained. Mold clamping block 2 up to meshing position
It is also possible to adjust the mold thickness by moving 0 and engaging the half nut 26 with the screw portion 14a of the tie bar 14 by the operation of the driving actuator 28.

Mold closing operation (high speed forward / low speed forward / low pressure mold clamping) The mold opening / closing servomotor 30 is driven to mold clamping block 2
0 and moving die plate 18 forward,
As shown in FIG. 1, the connecting plate 41, the piston rod 36, and the mold clamping ram 24 are in the retracted position, and the second switching valve 50
Is in a non-excited position.

The first switching valve 48 is in the neutral position, and the forward-moving oil chamber 21A and the backward-moving oil chamber 21B of the mold clamping cylinder 21 communicate with the tank 52. In this state,
By driving the mold opening / closing servomotor 30 at a high speed to rotate the ball screw shaft 32, along the ball screw shaft 32 screwed into the ball nut 33 attached to the mold clamping block 20, the mold clamping block 20 and The moving die plate 18 is advanced at high speed.

At a preset meshing position just before the forward limit position of the moving die plate 18, the half nut 26 is meshed with the threaded portion 14a of the tie bar 14 by the operation of the driving actuator 28, and the tie bar 14 is engaged.
And the mold clamping block 20 are engaged. After that, the second switching valve 50 is excited and switched, the passage 24b and the passage 24c are cut off, and the driving of the mold opening / closing servomotor 30 is stopped (see FIG. 8).

At the position where the half nut 26 and the screw portion 14a of the tie bar 14 mesh with each other, the mold clamping servomotor 44 is driven to move the piston rod 36 of the pressure boosting cylinder 22 forward. Since the passage 24b is blocked by the second switching valve 50, the piston rod 36 of the pressure boosting cylinder 22 is blocked.
The hydraulic thrust is generated in the retreating side oil chamber 22B as the vehicle moves forward (see FIG. 3). Due to this hydraulic thrust through the mold clamping ram 24, the moving die plate 18 advances at a low speed and low pressure,
The moving mold 16 advances to a position where it comes into contact with the fixed mold 10 (see FIGS. 4 and 8).

[0035]Mold clamping and boosting operation The second switching valve 50 is de-energized and the passage 24b and the passage 2
4c are communicated with each other, and the pressure increasing side (a
Side), and the retreating side oil chamber 21B of the mold clamping cylinder 21
And the forward side oil chamber 22A of the pressure boosting cylinder 22 to the tank 5
2 and connect to the forward side oil chamber 21A of the mold clamping cylinder 21.
Block passages through. Continue to the servomotor for mold clamping.
The actuator 44 is driven to drive the piston lock of the booster cylinder 22.
When the valve 36 is moved forward,
Due to the hydraulic pressure in 22B, the passage 24b and the second switching valve 5
0, the forward side of the mold clamping cylinder 21 communicated with the passage 24c
The oil chamber 21A is pressurized and pressed against the mold clamping ram 24 by a predetermined amount.
Pressure is applied to perform the mold clamping boosting operation (see FIGS. 5 and 8).
See).

Thereafter, a molten resin is injected and filled in the cavity provided between the fixed mold 10 and the movable mold 16 by an injection device (not shown). During this period, the mold clamping servomotor 44 is continuously driven with a predetermined torque with a mold clamping force commensurate with the ejection force.

Mold Opening Operation (High Pressure Opening) The opening side (b side) of the first switching valve 48 is excited to open the forward side oil chamber 21A of the mold clamping cylinder 21 to the tank 52,
A passage communicating with the retreating side oil chamber 21B of the mold clamping cylinder 21 is blocked. In this state, when the mold clamping servomotor 44 is reversely driven and the piston rod 36 of the pressure increasing cylinder 22 is retracted, the retreating side oil chamber 21B of the mold clamping cylinder 21 becomes the forward side oil chamber of the pressure increasing cylinder 22. An oil pressure is generated in 22A, and the pressure is increased via the passage 24a to press the mold clamping ram 24 in a predetermined manner to perform the mold opening operation (see FIGS. 6 and 8).

In this case, the first switching valve 48 is switched to the neutral position in the middle of the mold opening operation by the low speed and high pressure, the mold clamping servomotor 44 is continuously driven in the reverse direction, and the piston rod 36 of the pressure boosting cylinder 22 is retracted. By doing so, the piston 34 can be brought into contact with the left end wall surface of the retreating side oil chamber 22B of the pressure boosting cylinder 22 and the mold clamping ram 24 can be directly retracted.

In the case of a molded product which does not require a large mold opening force, the mold opening force can be set to be generated only by driving the mold clamping servomotor 44 from the beginning.

Mold retracting operation (high speed retracting) When the movable die plate 18 is retracted, the ball screw shafts 38, 38 are rotated by the driving of the mold clamping servomotor 44, and the connecting plate 41 is retracted to increase the pressure. The piston rod 36 of the cylinder 22 is retracted to move the piston 3
4 is brought into contact with the left end wall surface of the advancing side oil chamber 22A of the pressure boosting cylinder 22, and the mold clamping ram 24 is retracted.
It is brought into contact with the left end wall surface of the advancing side oil chamber 21A. At this time,
The first switching valve 48 is set to a neutral position, and the forward side oil chamber 21A and the backward side oil chamber 21B of the mold clamping cylinder 21 are
It communicates with the tank 52 (see FIGS. 7 and 8).

During the mold releasing operation, the half nut 26 is maintained in the state in which the actuator 28 is operating, that is, the meshing state with the screw portion 14a of the tie bar 14 is generated in order to generate the mold releasing force. If this state is not released, the mold clamping block 20 or the like cannot enter the high-speed retreat operation. Therefore, when the mold opening / retracting due to the high pressure reaches a position slightly retracted, the mold opening / closing servo motor 30
Is slightly reversely driven to loosen the meshing state between the half nut 26 and the screw portion 14a of the tie bar 14. While stopping the mold opening / closing servomotor 30, the half nut 26
The actuator 28 is operated to release the meshing between the half nut 26 and the screw portion 14a of the tie bar 14 and release the engagement between the tie bar 14 and the mold clamping block 20.

After that, the mold opening / closing servomotor 30 is driven again to rotate the ball screw shaft 32,
The mold clamping block 20 and the movable die plate 18 can be retreated at high speed along the ball screw shaft 32 screwed into the ball nut 33 attached to the mold clamping block 20. After that, a molded product (not shown) is extruded by an extruding device.

As is apparent from the above-described embodiments, in the mold clamping device such as the injection molding machine according to the present invention, the pressure is increased coaxially with the mold clamping ram operated by the mold clamping cylinder which is the driving means of the mold clamping mechanism. By providing the pressure boosting cylinder as a mechanism, the mold clamping ram can be directly operated by the pressure boosting piston. Further, by providing a pressure increasing mechanism inside the mold clamping ram, the entire length of the mold clamping device can be shortened and the structure can be made compact, and the thrust generated in the pressure intensifying cylinder is generated by the operation of the mold clamping ram. It can be added to the power, and the diameter of the mold clamping ram can be reduced to achieve a reduction in manufacturing cost.

Moreover, since the pressure increasing mechanism has the thrust / pressure generating function as well as the forward / backward movement of the piston, it is possible to eliminate wasteful operations such as filling of hydraulic oil. Also, the hydraulic oil in the mold clamping cylinder can be taken into the pressure boosting cylinder, and only the shortage and excess are supplied and discharged using the tank, so there is little fluctuation in the oil level in the tank, and therefore the tank capacity is reduced. Can be set small. By using the mold clamping ram and the pressure increasing mechanism together, the pressure in the mold clamping cylinder can be reduced and oil leakage can be reduced. Further, by using servo motors and the like for the drive sources of the mold clamping mechanism, the mold opening / closing mechanism, and the half nut together with the pressure increasing mechanism, a hydraulic pump is not required, and a complicated hydraulic circuit is omitted. Also, by directly mounting the second switching valve to the mold clamping block and the mold clamping ram, piping is eliminated, and a simple and compact device configuration allows complex mold opening / closing and mold clamping without causing oil leakage or noise. It is possible to obtain a mold clamping device that can smoothly perform an operation.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and many improvements and modifications can be made without departing from the spirit of the present invention. For example, in the embodiment, the case where the forward side oil chamber of the pressure boosting cylinder is communicated with the backward side oil chamber of the mold clamping cylinder via the passage is shown, but as an alternative, the backward side oil chamber of the pressure boosting cylinder is clamped. It is also possible to configure a passageway to the retreat side oil chamber of the cylinder, and to communicate the forward movement side oil chamber of the pressure boosting cylinder with the forward movement side oil chamber of the mold clamping cylinder via the passage. Further, the mold clamping device of the present invention is not limited to the mold clamping device of an injection molding machine, but can be similarly applied to a mold clamping device of a die casting machine, for example.

[0046]

As described above, in the mold clamping device such as the injection molding machine according to the present invention, the movable die plate in which the movable die is attached via the tie bar to the fixed die plate in which the fixed die is attached. And a moving means for moving the moving die plate forward and backward on the tie bar by arranging a mold clamping mechanism provided with a pressure increasing means via a tie bar behind the moving die plate. In a mold clamping device such as an injection molding machine provided with an engaging means for locking the movement at a predetermined position, the mold clamping mechanism includes a mold clamping cylinder for operating a mold clamping ram coupled to a movable die plate. The mold clamping block is equipped with a mold opening / closing servo motor moving means, and a pressure increasing cylinder is installed inside the mold clamping ram coaxially with the mold clamping ram. One end of the arranged piston rod is coupled to the outer surface of the mold clamping block so as to move forward and backward relatively by a required driving means, and each oil chamber of the pressure boosting cylinder and each oil chamber of the mold clamping cylinder are mutually connected. And a hydraulic circuit equipped with a switching valve that selectively communicates one or both of the oil chambers of the mold clamping cylinder with the block or tank. Can be incorporated,
By selectively increasing the pressure in the forward and backward oil chambers of the pressure boosting cylinder, the mold thickness adjustment operation,
All the functions of the mold opening operation and the boosting operation can be exerted, and the simple and quick mold opening / closing and mold clamping operations can be smoothly achieved, and efficient injection molding or the like can be performed.

[Brief description of 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 a schematic side view showing an outer side surface of a mold clamping block of the mold clamping device shown in FIG.

FIG. 3 is a schematic side view showing a mold closing operation of the mold clamping device shown in FIG.

FIG. 4 is a schematic side view showing a low pressure mold clamping operation of the mold clamping device shown in FIG.

5 is a schematic side view showing a boosting mold clamping operation of the mold clamping device shown in FIG. 1. FIG.

FIG. 6 is a schematic side view showing a mold opening operation of the mold clamping device shown in FIG. 1.

FIG. 7 is a schematic side view showing a mold opening and retracting operation of the mold clamping device shown in FIG.

FIG. 8 is a time chart showing the operating state of each component in the mold clamping device such as the injection molding machine according to the present invention.

[Explanation of symbols]

10 Fixed mold 12 Fixed die plate 14 Thai bar 14a screw part 16 Moving mold 18 Moving die plate 20 Mold clamping block 21 Mold clamping cylinder 21A Forward oil chamber 21B Reverse side oil chamber 22 Booster cylinder 22A Forward side oil chamber 22B Reverse side oil chamber 24 Mold clamping ram 24a, 24b, 24c passage 26 Half Nut 28 actuators 30-type opening / closing servo motor 30a output shaft 31 coupling 32 ball screw shaft 33 ball nut 34 Piston 36 piston rod 36a tip 38 Ball screw shaft 40 ball nut 41 Connection plate 42 Mounting plate 43 pulley 44 Servo motor for mold clamping 45 drive pulley 46 belt 48 1st switching valve (for boost / open switching) 50 Second switching valve (for low speed advance / low pressure mold clamping) 52 tank

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Claims (3)

(57) [Claims] 1. A movable die plate having a movable die attached thereto is movably opposed to a fixed die plate having a fixed die attached thereto via a tie bar, and is mounted behind the movable die plate via a tie bar. Injection by arranging a mold clamping mechanism provided with a pressure means, and providing a moving means for advancing and retracting the mold clamping mechanism and the movable die plate on a tie bar and an engaging means for locking the movement at a predetermined position. In a mold clamping device such as a molding machine, the mold clamping mechanism is composed of a mold clamping block equipped with a mold clamping cylinder that operates a mold clamping ram connected to a movable die plate,
A mold opening / closing servomotor moving means is connected to the mold clamping block, a pressure increasing cylinder is provided coaxially with the mold clamping ram, and one end of a piston rod inserted through the pressure increasing cylinder is clamped. The block is connected to the outer surface of the block so as to move back and forth relatively by a required driving means, and the oil chambers of the pressure boosting cylinder and the oil chambers of the mold clamping cylinder communicate with each other and the oil chamber of the mold clamping cylinder is connected to each other. A mold clamping device for an injection molding machine or the like, which is provided with a hydraulic circuit having a switching valve that selectively communicates one or both of them with a block or a tank. 2. One end of a piston rod inserted through the booster cylinder is fixed to a connecting plate connected to a ball nut screwed to a ball screw shaft rotatably connected to the outer surface of the mold clamping block, 3. A mold clamping servomotor driving means is coupled to one end of the ball screw shaft to move the connecting plate forward and backward along the ball screw shaft.
Mold clamping device such as the described injection molding machine. 3. The retreat side oil chamber defined by the mold clamping ram of the mold clamping cylinder communicates with the forward side oil chamber defined by the piston of the pressure boosting cylinder via a passage provided in the mold clamping ram. Then, the forward-side oil chamber of the mold clamping cylinder communicates with the backward-side oil chamber of the pressure increasing cylinder via a passage and an opening / closing valve provided in the mold clamping ram, and further the forward-side oil chamber of the mold clamping cylinder. The mold clamping device for an injection molding machine or the like according to claim 1, wherein one of or both of the oil chamber and the retreat side oil chamber are selectively connected to a block or a tank via a switching valve.