JPH04364917A - Mold clamping device for electrically driven injection molding machine - Google Patents

Abstract

PURPOSE:To provide a device which is small and can generate sufficient mold clamping force and mold opening force and realize the stabilized mold opening and closing operation. CONSTITUTION:A mold clamping cylinder 8 is disposed between either of a fixed platen 1 and a toggle support 4 and a tie bar 7, and oil chambers 8a and 8b are formed on both faces of a piston 9 of the mold clamping cylinder 8, and the piston 9 can be moved hydraulically at the time of mold opening to release easily. Also, high speed mold opening and closing can be performed by forming first, second and third oil chambers on the mold clamping cylinder 8 and feeding oil selectively to the oil chambers. That is, the oil for mold closing is fed to the first oil chamber, and the oil for mold clamping is fed for the second oil chamber, while the oil for mold opening is fed to the third oil chamber, and a pressurized area of the second oil chamber is set larger in comparison with pressurized areas of the first and third oil chambers. Therefore, when the oil is fed to the first and third oil chambers where pressurized areas are small, the piston 9 is moved more quickly by the difference between the small pressurized areas and the large pressurized area.

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 for an electric injection molding machine.

0002

[Prior Art] Conventionally, resin that has been heated and fluidized in a heating cylinder is injected into a mold at high pressure, and then cooled in the mold.
Electric injection molding machines that solidify or harden the resin and then open the mold to take out the molded product are equipped with a mold clamping device to prevent the resin filled in the mold cavity from leaking from the mating surfaces. The mold clamping device opens and closes the mold using a toggle mechanism or a ball screw feeding mechanism, and clamps the mold using a mold clamping cylinder.

In this case, when the mold clamping is completed, the pressure oil in the mold clamping cylinder is discharged, and the mold is opened by the toggle mechanism or ball screw feeding mechanism (Japanese Patent Laid-Open No. 3-392
(See Publication No. 23). FIG. 2 is a schematic diagram of a mold clamping device of a conventional electric injection molding machine. In the figure, 1 is a fixed platen;
2 is a movable platen, and a mold 3a is attached to the fixed platen 1, and a mold 3b is attached to the movable platen 2. A toggle support 4 is movable on a base 5, and a single toggle mechanism 6 attached to the toggle support moves the movable platen 2 to close the mold.

Four tie bars 7 parallel to each other are attached to the four corners of the toggle support 4, and these tie bars 7 can slide through holes 2a and 1a provided in the movable platen 2 and fixed platen 1. It penetrates through. and,
The other end of each tie bar 7 is fixed to a piston 9 of a mold clamping cylinder 8. The oil chamber on the rod side of the mold clamping cylinder 8 communicates with a small hydraulic pressure generating unit 11 via a pipe 10.

The single toggle mechanism 6 includes a bracket 12 fixed to the toggle support 4;
A first link 13 rotatably supported by the movable platen 2, a second link 14 pivotally connected to the first link 13, and a bracket 15 rotatably supporting the second link 14 and fixed to the movable platen 2. The shaft of the first link 13, that is, the drive shaft 16 is connected to a motor with a speed reducer (for example, a servo motor and a planetary gear speed reducer), which are not shown. The lengths of the first link 13 and the second link 14 are set so that the molds 3a and 3b are closed when they are in a straight line (actually, this setting is made by adjusting the mold thickness (not shown). (performed by the organization).

Reference numeral 17 denotes a stopper fixed to the toggle support 4, which restricts the rotation of the first link 13 in the direction of arrow a in the figure and maintains the dead center position of the single toggle mechanism 6. In addition, in this state, the molds 3a and 3b
are in complete contact with each other, and the mold is clamped by the mold clamping cylinder 8. Further, in the case of the mold clamping cylinder 8 of the above embodiment, the piston 9 is fixed to the end of the tie bar 7, but the structure is not limited to this, and for example, a hydraulic cylinder may be attached to the end of the tie bar 7. good. Furthermore, although the mold clamping cylinder 8 is provided on the fixed platen 1 side, it may be provided on the toggle support 4 side.

Next, the opening/closing operation of the mold by the mold clamping device will be explained. The motor with a speed reducer is driven to rotate the first link 13 in the direction of the arrow a shown in the figure via the drive shaft 16, and the first link 13 and the second link 14 are extended almost in a straight line. The first link 13 is positioned and fixed at the dead center position of the mechanism 6. At this time, the molds 3a and 3b come into contact with each other, and the motor with a reduction gear presses the first link 13 against the stopper 17 with a minute torque to place it in a stable position.

After the first link 13 is positioned at the dead center position of the single toggle mechanism 6, hydraulic pressure is applied to the oil chamber on the rod side of the mold clamping cylinder 8 provided at the ends of the four tie bars 7. , pulls the tie bar 7 via the piston 9, generates a uniform and stable mold clamping force, and closes the molds 3a, 3b.
Close the mold by bringing them into close contact. When opening the mold, the oil pressure in the oil chamber of the mold clamping cylinder 8 is set to zero, and then the first link 13 of the single toggle mechanism 6 is rotated counterclockwise (opposite to the direction of arrow a in the figure).

In the mold clamping device of the electric injection molding machine configured as described above, a motor with a speed reducer is used to move the movable platen 2, and a mold clamping cylinder is used to generate the mold clamping force, so that the speed reduction is reduced. The attached motor can be made smaller.

0010

[Problems to be Solved by the Invention] However, the mold clamping device of the conventional electric injection molding machine described above cannot generate a sufficient mold opening force, so it is difficult to separate the molds 3a, 3b and the molded product. If molding is performed that requires a large amount of force when opening the mold, it will be difficult to open the mold. In addition, since a small motor with a speed reducer is used to move the movable platen 2, if sufficient mold opening force is not obtained or if molding is performed using a spring-loaded mold, it is difficult to obtain sufficient mold clamping force. I can't.

The present invention solves the problems of the mold clamping device of the conventional electric injection molding machine described above, is small in size, can generate sufficient mold opening force and mold clamping force, and can perform stable mold opening and closing operations. An object of the present invention is to provide a mold clamping device for an electric injection molding machine that can be realized.

0012

[Means for Solving the Problems] To this end, in the mold clamping device of the electric injection molding machine of the present invention, a fixed platen,
a toggle support disposed facing the fixed platen; a movable platen disposed between the fixed platen and the toggle support and moving back and forth along the tie bar; a motor disposed between the toggle support and the movable platen; By driving the motor, the movable platen can be moved forward and backward relative to the fixed platen, and the molds can be moved toward and away from each other.

A mold clamping cylinder is disposed between either the fixed platen or the toggle support and the tie bar,
By changing the relative positions of the two, tensile force can be applied to the tie bars and mold clamping force can be generated. In this case, since oil chambers are formed on both sides of the piston of the mold clamping cylinder, the piston can be moved hydraulically when the mold is opened.

[0014]The mold clamping cylinder has first, second,
By forming a third oil chamber and selectively supplying and discharging oil to the oil chamber, high-speed mold opening and closing can be performed. That is, the first oil chamber is supplied with oil for closing the mold, the second oil chamber is supplied with oil for clamping the mold, the third oil chamber is supplied with oil for opening the mold, and the third oil chamber is supplied with oil for mold opening. The pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers.

[0015]

[Operation] According to the present invention, as described above, a fixed platen, a toggle support disposed opposite to the fixed platen, and a toggle support disposed between the fixed platen and the toggle support,
It has a movable platen that moves forward and backward along the tie bar, and a toggle mechanism that is disposed between the toggle support and the movable platen and is operated by a motor.The motor is driven to move the movable platen forward and backward relative to the fixed platen. The mold can be brought into contact with and separated from the mold. That is, the mold can be closed by moving the movable platen toward the fixed platen, and the mold can be opened by moving the movable platen toward the toggle support.

[0016] A mold clamping cylinder is disposed between either the fixed platen or the toggle support and the tie bar. Therefore, after the mold is closed, oil is supplied to the oil chamber of the mold clamping cylinder, and by changing the relative position of the tie bar with either the fixed platen or the toggle support, tensile force is applied to the tie bar, and the mold is clamped. can generate force.

In this case, since oil chambers are formed on both sides of the piston of the mold clamping cylinder, the piston can be moved by hydraulic pressure when the mold is opened, and mold release becomes easy. First, second, and third oil chambers are formed in the mold clamping cylinder, and by selectively supplying and discharging oil to the oil chambers, high-speed mold opening and closing can be performed. . That is, the first oil chamber is supplied with oil for closing the mold, the second oil chamber is supplied with oil for clamping the mold, the third oil chamber is supplied with oil for opening the mold, and the third oil chamber is supplied with oil for mold opening. The pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers. therefore,
When oil is supplied to the first oil chamber and the third oil chamber, since the pressure receiving area is small, the piston moves faster.

[0018]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a mold clamping device for an electric injection molding machine according to the present invention. In the figure, 1 is a fixed platen, 2 is a movable platen, and a mold 3a is attached to the fixed platen 1, and a mold 3b is attached to the movable platen 2. 4 is a toggle support that can be moved on the base 5;
The mold is closed by moving the movable platen 2 by a single toggle mechanism 6 attached thereto.

Four tie bars 7 parallel to each other are attached to the four corners of the toggle support 4, and these tie bars 7 can slide through holes 2a and 1a provided in the movable platen 2 and fixed platen 1. It penetrates through. and,
The other end of each tie bar 7 is fixed to a piston 9 of a mold clamping cylinder 8. The piston 9 has an oil chamber 8a on the rod side and an oil chamber 8b on the non-rod side in the mold clamping cylinder 8.
form. The oil chamber 8a is connected to the oil chamber 8a via a pipe 21.
b communicates with the small hydraulic pressure generating unit 11 via a pipe 22. 23 is an electromagnetic switching valve disposed between the mold clamping cylinder 8 and the small hydraulic pressure generating unit 11. The electromagnetic switching valve 23 is switched by solenoids a and b,
When solenoid a is energized, it is in position A, and when solenoid b is energized, it is in position B. Then, the electromagnetic switching valve 2
3 can be operated to selectively supply oil to the oil chambers 8a and 8b. That is, when the oil is supplied to the oil chamber 8a, the tie bar 7 is pulled, a mold clamping force is generated, and the oil chamber 8a is supplied.
When supplied to b, a mold opening force is generated.

The single toggle mechanism 6 includes a bracket 12 fixed to the toggle support 4;
The movable platen 2 has a first link 13 that is rotatably supported by the movable platen 2, a second link 14 that is pivotally connected to the first link 13, and a bracket 15 that rotatably supports the second link 14 and is fixed to the movable platen 2. The shaft of the first link 13, that is, the drive shaft 16 is connected to a motor with a speed reducer (for example, a servo motor and a planetary gear speed reducer), which are not shown. The lengths of the first link 13 and the second link 14 are set so that the molds 3a and 3b are closed when they are in a straight line (actually, this setting is made by adjusting the mold thickness (not shown). (performed by the organization).

Reference numeral 17 denotes a stopper fixed to the toggle support 4, which restricts the rotation of the first link 13 in the direction of arrow a in the figure and maintains the dead center position of the single toggle mechanism 6. In addition, in this state, the molds 3a and 3b
are in complete contact with each other, and the mold is clamped by the mold clamping cylinder 8. Further, in the case of the mold clamping cylinder 8 of the above embodiment, the piston 9 is fixed to the end of the tie bar 7, but the structure is not limited to this, and for example, a hydraulic cylinder may be attached to the end of the tie bar 7. good. Furthermore, although the mold clamping cylinder 8 is provided on the fixed platen 1 side, it may be provided on the toggle support 4 side.

Next, the molds 3a and 3b are removed by the mold clamping device.
The opening/closing operation will be explained using FIGS. 3 and 4 together. FIG. 3 is a state diagram during mold clamping operation, and FIG. 4 is a state diagram during mold opening operation. The motor with a speed reducer is driven to rotate the first link 13 in the direction of the arrow a shown in the figure via the drive shaft 16, and the first link 13 and the second link 14 are extended almost in a straight line. Dead center position of mechanism 6)
The first link 13 is positioned and fixed. At this time, the molds 3a and 3b come into contact with each other, and the motor with a reduction gear presses the first link 13 against the stopper 17 with a minute torque to place it in a stable position.

After the first link 13 is positioned at the dead center position of the single toggle mechanism 6, the solenoid b is energized to place the electromagnetic switching valve 23 in the B position, as shown in FIG. As a result, oil is supplied to the oil chamber 8a through the piping 21, and the tie bar 7 is pulled through the piston 9, generating a uniform and stable mold clamping force to bring the molds 3a and 3b into close contact and clamp the molds. conduct.

When opening the mold, the solenoid a is energized and the electromagnetic switching valve 23 is placed in the A position as shown in FIG. As a result, the pressure in the oil chamber 8a is evacuated, and oil is supplied to the oil chamber 8b via the pipe 22, and a uniform and stable mold opening force can be generated to separate the mold 3b from the mold 3a. After that, the first of the single toggle mechanism 6
Rotate the link 13 counterclockwise (opposite the direction of arrow a in the figure).

FIG. 5 is a schematic diagram of a mold clamping device for an electric injection molding machine showing a second embodiment of the present invention. In the figure, 7 is a tie bar, 31 is a mold clamping cylinder attached to the fixed platen 1 (see FIG. 1), and 32 is slidably disposed within the mold clamping cylinder 31 and fixed to the end of the tie bar 7. It is a piston that has been A small diameter rod 33 is provided on the tie bar 7 side of the piston 32, and a large diameter rod 34 is provided on the opposite side so as to pass through the wall of the clamping cylinder 31, and an oil chamber 35 is provided around the tie bar 7. However, an oil chamber 36 is formed around the small diameter rod 33, and an oil chamber 37 is formed around the large diameter rod 34. Also, A1 , A2 , A3
is the pressure receiving area of each oil chamber 35, 36, 37.

The pressure-receiving areas A1 and A3 are designed to be sufficiently smaller (for example, 1/10) than the pressure-receiving area A2, and although the maximum thrust is small, the pressure-receiving areas A1 and A3 are designed to be sufficiently smaller than the pressure-receiving area A2. The amount of oil supplied to the oil chamber 36 is smaller than the amount of oil supplied to the oil chamber 36, and by supplying oil to the oil chamber 35, high-speed mold closing can be performed.
High-speed mold opening can be achieved by supplying oil to the mold.

The oil chambers 35, 36, 37 are provided with piping 39,
40 and 41 are connected. The pipes 39 and 41 are connected to an electromagnetic switching valve 45, and oil can be selectively supplied to the oil chambers 35 and 37 by switching the electromagnetic switching valve 45. The electromagnetic switching valve 45 has solenoids a and b, and takes the A position, the B position, and the neutral N position by energizing the solenoids a and b.

46 is an oil pump, 47 is an oil tank, and 48 is a proportional pressure reducing valve for reducing the pressure of oil discharged from the oil pump 46. Then, the solenoid a is energized and the electromagnetic switching valve 45 is placed in the A position,
The oil from the oil pump 46 is supplied to the oil chamber 35, the solenoid b is energized, the electromagnetic switching valve 45 is placed in the B position, the oil from the oil pump 46 is supplied to the oil chamber 37, and the oil in the oil chamber 35 is can be discharged into the oil tank 47.

[0029] Furthermore, the pipes 39 and 40 are connected to the relief valve 4.
9 , and the pipe 40 communicates with a reservoir 51 via a prefill valve 50 with a pilot. The pilot pressure of the pilot-equipped prefill valve 50 is taken from the piping 41. The operation of the mold clamping device of the electric injection molding machine having the above configuration will be explained with reference to FIG.

FIG. 6 is a characteristic diagram of the mold clamping cylinder. The movable platen 1 is moved via the single toggle mechanism 6 (see Fig. 1) by activating the motor with a speed reducer to close the mold.
The molds 3a and 3b are brought into contact. Next, the electromagnetic switching valve 45 (
Oil is supplied to the oil chamber 35 by energizing the solenoid a (see FIG. 5). At this time, the pressure in the oil chamber 35 is
It changes as shown in FIG. 6 depending on the contact state of a and 3b.

That is, before the molds 3a and 3b come into contact, the pressure is low because the resistance such as the spring force and the friction force of the guide pin is small, and when the set pressure of the relief valve 49 is increased to above this value, the oil pump 46 The oil discharged from the piston 32 flows only into the oil chamber 35, and since the pressure receiving area A1 is small, the piston 32 can be retreated at high speed. At this time, oil from the reservoir 51 is also sucked into the oil chamber 36 via the prefill valve 50 with a pilot.

Next, when the molds 3a and 3b come into contact, the pressure in the oil chamber 35 increases rapidly as shown in FIG. 6 to compress them. When the pressure exceeds the set pressure of the relief valve 49, oil begins to flow into the oil chamber 36 through the relief valve 49. Since the pressure receiving area A2 of the oil chamber 36 is large enough to generate mold clamping force, the tensile force of the tie bar 7 increases rapidly. Then, the pressure within the pipes 39 and 40 rises to the set pressure of the proportional pressure reducing valve 48, at which point the flow of oil stops.

On the other hand, when opening the mold, the electromagnetic switching valve 4
When solenoid b of No. 5 is energized, oil is supplied into the oil chamber 37, and the pressure inside the oil chamber 37 rises. This pressure opens the pilot-equipped prefill valve 50, and the high-pressure oil inside the oil chamber 36 is opened. is returned to the reservoir 51 via the pilot prefill valve 50. The oil in the oil chamber 35 then passes through the electromagnetic switching valve 45 and returns to the oil tank 47. In this way, the piston 32 moves and finally comes into contact with the end surface of the oil chamber 36 and stops.

In the mold clamping device of the electric injection molding machine having the above structure, the strokes for clamping and opening the mold are increased without increasing the capacity of the oil pump 46, and as a result, molds with springs or a large mold opening force can be used. In the case of a mold that requires a single toggle mechanism 6, it is possible to compensate for the lack of capacity of the motor with a reduction gear that drives the single toggle mechanism 6. Since the pressure receiving areas A1 and A3 of the oil chambers 35 and 37 are small, the stroke of the piston 32 can be lengthened for a constant amount of oil, so the molds 3a and 3b can be opened by a sufficient distance.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0036]

As described above in detail, according to the present invention, there is a fixed platen, a toggle support disposed opposite to the fixed platen, and a toggle support disposed between the fixed platen and the toggle support. , a movable platen that moves forward and backward along the tie bar, and a toggle mechanism that is disposed between the toggle support and the movable platen and is operated by a motor. A mold clamping cylinder is disposed between either the fixed platen or toggle support and the tie bar, and oil chambers are formed on both sides of the piston of the mold clamping cylinder, so the piston is moved by hydraulic pressure when the mold is opened. This makes it easier to release the mold. Therefore, even when performing molding that requires a large force when releasing the mold and the molded product, the mold opening operation becomes easy.

[0037] Then, the first, second,
By forming a third oil chamber and selectively supplying and discharging oil to the oil chamber, high-speed mold opening and closing can be performed. That is, the first oil chamber is supplied with oil for closing the mold, the second oil chamber is supplied with oil for clamping the mold, the third oil chamber is supplied with oil for opening the mold, and the third oil chamber is supplied with oil for mold opening. The pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers. Therefore, when oil is supplied to the first oil chamber and the third oil chamber, since the pressure receiving area is small, the piston can be moved faster accordingly. Further, since the pressure receiving area of the second oil chamber is made large, sufficient mold clamping force can be generated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a mold clamping device of an electric injection molding machine of the present invention.

FIG. 2 is a schematic diagram of a mold clamping device of a conventional electric injection molding machine.

FIG. 3 is a state diagram during mold clamping operation.

FIG. 4 is a state diagram during mold opening operation.

FIG. 5 is a schematic diagram of a mold clamping device of an electric injection molding machine showing a second embodiment of the present invention.

FIG. 6 is a characteristic diagram of a mold clamping cylinder.

[Explanation of symbols]

1 Fixed platen 2 Movable platen 4 Toggle support 6 Single toggle mechanism (toggle mechanism) 7
Tie bar 8 Clamping cylinder 9 Piston 8a, 8b Oil chamber

Claims (2)

[Claims] Claim 1: (a) a fixed platen; (b) a toggle support disposed opposite the fixed platen; (c)
) a movable platen disposed between the fixed platen and the toggle support and moving back and forth along the tie bar; (d) a toggle mechanism disposed between the toggle support and the movable platen and operated by a motor; (e) the above. a mold clamping cylinder disposed between either the fixed platen or the toggle support and the tie bar and applying a tensile force to the tie bar by changing the relative position of the two; (f) formed on both sides of the piston of the mold clamping cylinder; 1. A mold clamping device for an electric injection molding machine, comprising means for selectively supplying and discharging oil to and from an oil chamber. 2. (a) a fixed platen; (b) a toggle support disposed opposite the fixed platen; (c)
) a movable platen disposed between the fixed platen and the toggle support and moving back and forth along the tie bar; (d) a toggle mechanism disposed between the toggle support and the movable platen and operated by a motor; (e) the above. (f) a mold clamping cylinder disposed between either the fixed platen or the toggle support and the tie bar and applying a tensile force to the tie bar by changing the relative position of the two; (f) a first mold clamping cylinder formed on the mold clamping cylinder; , a means for selectively supplying and discharging oil to and from the second and third oil chambers; (g) mold closing oil is supplied to the first oil chamber and to the second oil chamber; The oil for mold clamping is supplied to the third oil chamber, the oil for opening the mold is supplied to the third oil chamber, and the pressure receiving area of the second oil chamber is compared to the pressure receiving area of the first and third oil chambers. A mold clamping device for an electric injection molding machine characterized by a large setting.