JP2875060B2 - Mold clamping device for electric injection molding machine - 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 for an electric injection molding machine.

[0002]

2. Description of the Related Art Conventionally, a resin heated and fluidized in a heating cylinder is injected into a mold at a high pressure and cooled therein.
In an electric injection molding machine which solidifies or hardens and then opens a mold to take out a molded product, a mold clamping device is provided so that resin filled in a cavity of the mold does not leak from a mating surface. The mold clamping device opens and closes the mold with a toggle mechanism or a ball screw feed mechanism, and performs mold clamping with a mold clamping cylinder.

In this case, when the mold clamping is completed, the pressure oil of the mold clamping cylinder is discharged, and the mold is opened by the toggle mechanism or the ball screw feed mechanism (Japanese Patent Laid-Open No. 3-392).
No. 23). FIG. 2 is a schematic view of a mold clamping device of a conventional electric injection molding machine. In the figure, 1 is a fixed platen,
Reference numeral 2 denotes a movable platen.
However, a mold 3 b is attached to the movable platen 2.
Reference numeral 4 denotes a toggle support that can move on a base 5, and the movable platen 2 is moved by a single toggle mechanism 6 attached to the support to perform mold closing.

At the four corners of the toggle support 4, four tie bars 7 parallel to each other are attached, and these tie bars 7 can slide through holes 2a, 1a provided in the movable platen 2 and the fixed platen 1. 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 on the first link 13, a second link 14 pivotally connected to the first link 13, 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 (not shown) (for example, a servo motor and a planetary gear speed reducer).
The lengths of the first link 13 and the second link 14 are set so that the dies 3a and 3b are closed when they are in a straight line (actually, this setting is not shown in the mold thickness adjustment). It is performed by a mechanism.).

Reference numeral 17 denotes a stopper fixed to the toggle support 4. The stopper 17 restricts the rotation of the first link 13 in the direction of arrow a in the drawing, and holds the dead center position of the single toggle mechanism 6. In this state, the dies 3a, 3b
Are completely in contact with each other and are 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. However, the present invention is not limited to this. 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 and closing operation of the mold by the mold clamping device will be described. By driving the motor with a speed reducer, the first link 13 is rotated in the direction of arrow a through the drive shaft 16 so that 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 the speed reducer causes the first link 13 to move the stopper 17 with a slight torque.
And 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 an oil chamber on the rod side of the mold clamping cylinder 8 provided at the end of the four tie bars 7. The tie bar 7 is pulled through the piston 9 to generate a uniform and stable mold clamping force so that the dies 3a, 3
b is brought into close contact and the mold is clamped. When opening the mold, the hydraulic pressure in the oil chamber of the mold clamping cylinder 8 is reduced to zero, and then the first link 13 of the single toggle mechanism 6 is rotated counterclockwise (reverse to the direction of arrow a in the drawing).

In the mold clamping apparatus for an electric injection molding machine having the above-described structure, a motor with a speed reducer is used to move the movable platen 2 and a mold clamping cylinder is used to generate a mold clamping force. The motorized motor can be reduced in size.

[0010]

However, in the above-described conventional mold clamping device of an electric injection molding machine, a sufficient mold opening force cannot be generated, so that the molds 3a and 3b and the molded product are separated from each other. When molding is performed such that a large force is required at the time of performing, the mold opening operation becomes difficult. In addition, since a small motor with a reducer is used to move the movable platen 2, if the mold opening force cannot be obtained sufficiently, or if molding is performed using a spring-loaded mold, it is necessary to obtain sufficient mold clamping force. Can not.

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

[0012]

For this purpose, a mold clamping apparatus for an electric injection molding machine according to the present invention comprises a stationary platen,
A toggle support disposed opposite to the fixed platen, a movable platen disposed between the fixed platen and the toggle support, and advanced and retracted along a tie bar; and a movable platen disposed between the toggle support and the movable platen. And a toggle mechanism actuated by a motor.

[0013] A mold clamping cylinder, which is disposed between one of the fixed platen and the toggle support and the tie bar and has oil chambers formed on both sides of a piston, is provided in each of the oil chambers. A supply / discharge unit for selectively supplying and discharging oil to apply a tensile force to the tie bar to perform mold clamping and open the mold.

According to another aspect of the present invention, there is provided a mold clamping device for an electric injection molding machine, comprising: a fixed platen; a toggle support provided to face the fixed platen; and a toggle support provided between the fixed platen and the toggle support. A movable platen that advances and retreats along a tie bar, a toggle mechanism that is disposed between the toggle support and the movable platen, and is operated by a motor; and one of the fixed platen and the toggle support and the tie bar. And a small-diameter rod on the tie-bar side of the piston, a first oil chamber on the tie-bar side of the small-diameter rod, a second oil chamber on the tie-bar side of the piston, and the piston A mold clamping cylinder having a third oil chamber formed on the opposite side of the first oil chamber;
To a third oil chamber for selectively supplying and discharging oil to and from the third oil chamber. 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]

According to the present invention, in the mold clamping device of the electric injection molding machine as described above, the fixed platen, the toggle support disposed opposite to the fixed platen, the fixed platen and the toggle support are provided. And 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 that is operated by a motor. A mold clamping cylinder disposed between one of the fixed platen and the toggle support and the tie bar and having oil chambers formed on both sides of a piston; And a supply / discharge means for selectively clamping and supplying the tie bar to apply a tensile force to the tie bar to perform mold clamping and open the mold.

In this case, oil chambers are formed on both sides of the piston, and by selectively supplying and discharging oil to and from each oil chamber, after closing the mold, a tensile force is applied to the tie bar to close the mold. It can be carried out. Further, by selectively supplying and discharging oil to and from each oil chamber, the mold can be opened and the mold can be released.

According to another aspect of the present invention, there is provided a mold clamping apparatus for an electric injection molding machine, comprising: a fixed platen; a toggle support disposed to face the fixed platen; and a toggle support disposed between the fixed platen and the toggle support. A movable platen that advances and retreats along a tie bar, a toggle mechanism that is disposed between the toggle support and the movable platen, and is operated by a motor; and one of the fixed platen and the toggle support and the tie bar. And a small-diameter rod on the tie-bar side of the piston, a first oil chamber on the tie-bar side of the small-diameter rod, a second oil chamber on the tie-bar side of the piston, and the piston A mold clamping cylinder having a third oil chamber formed on the opposite side of the first oil chamber;
To a third oil chamber for selectively supplying and discharging oil to and from the third oil chamber. The pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers. In this case, since the pressure receiving area of the second oil chamber is set to be larger than the pressure receiving areas of the first and third oil chambers, the piston moves quickly when oil is supplied to the first and third oil chambers.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of a mold clamping device of 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 movable platen 2 is moved by the single toggle mechanism 6 attached thereto to close the mold.

At the four corners of the toggle support 4, four tie bars 7 parallel to each other are attached, and these tie bars 7 can slide through holes 2a, 1a provided in the movable platen 2 and the fixed platen 1. 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 is provided within the mold clamping cylinder 8 with a rod-side oil chamber 8a and a non-rod-side oil chamber 8b.
To form The oil chamber 8a is connected to the oil chamber 8 via a pipe 21.
“b” communicates with the small hydraulic pressure generating unit 11 via a pipe 22. Reference numeral 23 denotes 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,
The position A is set when the solenoid a is excited, and the position B is set when the solenoid b is excited. And 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 to generate a mold clamping force.
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,
A first link 13 rotatably supported on the first link 13, a second link 14 pivotally connected to the first link 13, 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 (not shown) (for example, a servo motor and a planetary gear speed reducer).
The lengths of the first link 13 and the second link 14 are set so that the dies 3a and 3b are closed when they are in a straight line (actually, this setting is not shown in the mold thickness adjustment). It is performed by a mechanism.).

Reference numeral 17 denotes a stopper fixed to the toggle support 4. The stopper 17 restricts the rotation of the first link 13 in the direction of the arrow a in the drawing, and holds the dead center position of the single toggle mechanism 6. In this state, the dies 3a, 3b
Are completely in contact with each other and are 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 invention is not limited to this. 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 dies 3a, 3b by the mold clamping device
Will be described with reference to FIGS. 3 and 4. FIG.
FIG. 3 is a state diagram at the time of the mold clamping operation, and FIG. 4 is a state diagram at the time of the mold opening operation. By driving the motor with a speed reducer, the first link 13 is rotated in the direction of arrow a through the drive shaft 16 so that the first link 13 and the second link 14 are extended almost in a straight line. Dead center position of mechanism 6)
To position and fix the first link 13. At this time, the molds 3a and 3b come into contact with each other, and the motor with a speed reducer presses the first link 13 against the stopper 17 with a small torque to place the first link 13 at 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 excited to place the electromagnetic switching valve 23 at the position B as shown in FIG. As a result, oil is supplied to the oil chamber 8a via the pipe 21, and the tie bar 7 is pulled via the piston 9 to generate a uniform and stable mold clamping force to bring the molds 3a and 3b into close contact to close the mold. Do.

When the mold is opened, the solenoid a is excited to place the electromagnetic switching valve 23 at the position A as shown in FIG. As a result, the oil chamber 8a is exhausted and the oil is supplied to the oil chamber 8b via the pipe 22, thereby generating a uniform and stable mold opening force and separating the mold 3b from the mold 3a. Then, the first of the single toggle mechanism 6
The link 13 is rotated in a counterclockwise direction (reverse to the direction of arrow a in the drawing).

FIG. 5 is a schematic view of a mold clamping device of 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), 32 is slidably disposed in the mold clamping cylinder 31 and is fixed to an end of the tie bar 7. It is the piston that was done. 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 penetrate the wall of the mold clamping cylinder 31. 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. A ₁ , A ₂ and A ₃ are pressure receiving areas of the respective oil chambers 35, 36 and 37.

Since the pressure receiving areas A ₁ and A ₃ are designed to be sufficiently smaller (for example, 1/10) than the pressure receiving area A ₂ , the maximum thrust generated is small, but the piston 32 is moved. Therefore, the amount of oil supplied to the oil chambers 35 and 37 is smaller than the amount of oil supplied to the oil chamber 36, and by supplying oil to the oil chambers 35 and 37,
Can be moved faster.

In the oil chambers 35, 36, 37, pipes 39,
40 and 41 are connected. The pipes 39 and 41 are connected to an electromagnetic switching valve 45, and the oil can be selectively supplied to the oil chambers 35 and 37 by switching the electromagnetic switching valve 45. The solenoid-operated switching valve 45 has solenoids a and b. When the solenoids a and b are excited, the solenoid switching valve 45 assumes the A position, the B position, and the N position in the neutral state.

Reference numeral 46 denotes an oil pump; 47, an oil tank; and 48, a proportional pressure reducing valve for reducing the pressure of oil discharged from the oil pump 46. Then, the solenoid a is excited to place the electromagnetic switching valve 45 at the position A, oil from the oil pump 46 is supplied to the oil chamber 35, and the solenoid b is excited to place the electromagnetic switching valve 45 at the position B. The oil in the pump 46 can be supplied to the oil chamber 37 and the oil in the oil chamber 35 can be discharged to the oil tank 47.

The pipes 39 and 40 are connected to the relief valve 4.
9, and the pipe 40 communicates with a reservoir 51 via a pilot-filled prefill valve 50. The pilot pressure of the prefill valve with pilot 50 is taken from a pipe 41. The operation of the mold clamping device of the electric injection molding machine having the above configuration will be described 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 operating the motor with a speed reducer, and the mold is closed.
The molds 3a and 3b are brought into contact. Next, the electromagnetic switching valve 45
The oil is supplied to the oil chamber 35 by exciting the solenoid a (see FIG. 5). At this time, the pressure in the oil chamber 35 changes as shown in FIG. 6 depending on the contact state of the molds 3a and 3b.

That is, before the molds 3a and 3b come into contact with each other, the pressure is low because the resistance such as the spring force and the frictional force of the guide pin is small. The oil discharged from the oil chamber 35
Only flows in, the piston 32 can be retracted at a high speed because the pressure receiving area A ₁ is small. At this time, the oil in the reservoir 51 is sucked into the oil chamber 36 via the prefill valve 50 with pilot.

Next, when the molds 3a and 3b come into contact with each other, the pressure in the oil chamber 35 rises rapidly as shown in FIG. 6 to compress them. When the pressure exceeds the set pressure of the relief valve 49, the oil starts flowing through the relief valve 49 to the oil chamber 36 as well. Since the pressure receiving area A ₂ of the oil chamber 36 is large enough to generate a clamping force, tensile force of the tie bar 7 is rapidly increased.
Then, the pressure in the pipes 39 and 40 rises to the set pressure of the proportional pressure reducing valve 48, at which point the oil flow stops.

On the other hand, when the mold is opened, the electromagnetic switching valve 4
When the solenoid b is excited, oil is supplied into the oil chamber 37, and the pressure in the oil chamber 37 rises. This pressure opens the pilot-filled prefill valve 50, and the high-pressure oil in the oil chamber 36. Is returned to the reservoir 51 via the prefill valve 50 with pilot. Then, the oil in the oil chamber 35 returns to the oil tank 47 through the electromagnetic switching valve 45. In this way, the piston 32 moves and finally stops in contact with the end face of the oil chamber 36.

In the mold clamping device of the electric injection molding machine having the above structure, the stroke of the mold clamping and the mold opening is increased without increasing the capacity of the oil pump 46. In the case of a mold that requires a motor, the capacity shortage of the motor with a speed reducer that drives the single toggle mechanism 6 can be compensated. Since the pressure receiving areas A ₁ and A _{3 of the} oil chambers 35 and 37 are small, the stroke of the piston 32 can be lengthened for a fixed oil amount.
a, 3b can be opened a sufficient distance.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist 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, in a mold clamping device for an electric injection molding machine, a fixed platen, a toggle support disposed to face the fixed platen, A movable platen disposed between the fixed platen and the toggle support and advancing and retracting along the tie bar; a toggle mechanism disposed between the toggle support and the movable platen and operated by a motor; A mold clamping cylinder, which is disposed between one of the toggle supports and the tie bar and has oil chambers formed on both sides of the piston, selectively supplies and discharges oil to and from each of the oil chambers. In this case, the tie bar is provided with a supply / discharge unit for applying a tensile force to the tie bar for clamping the mold and opening the mold. In this case, since the mold can be opened by moving the piston by hydraulic pressure, the mold can be easily released. Therefore, even when molding is performed that requires a large force to perform mold release, a sufficient mold opening force can be generated in a small mold clamping device, and a stable mold opening and closing operation can be realized. Can be.

According to another aspect of the present invention, there is provided a mold clamping device for an electric injection molding machine, comprising: a fixed platen; a toggle support provided to face the fixed platen; and a toggle support provided between the fixed platen and the toggle support. A movable platen that advances and retreats along a tie bar, a toggle mechanism that is disposed between the toggle support and the movable platen, and is operated by a motor; and one of the fixed platen and the toggle support and the tie bar. And a small-diameter rod on the tie-bar side of the piston, a first oil chamber on the tie-bar side of the small-diameter rod, a second oil chamber on the tie-bar side of the piston, and the piston A mold clamping cylinder having a third oil chamber formed on the opposite side of the first oil chamber;
To a third oil chamber for selectively supplying and discharging oil to and from the third oil chamber. The pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers. In this case, when oil is supplied to the first and third oil chambers, the piston can be moved faster by an amount corresponding to a smaller pressure receiving area than the second oil chamber. Further, since the pressure receiving area of the second oil chamber is set larger than the pressure receiving areas of the first and third oil chambers,
A sufficient mold clamping force can be generated.

[Brief description of the drawings]

FIG. 1 is a schematic view of a mold clamping device of an electric injection molding machine according to 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 a mold clamping operation.

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

FIG. 5 is a schematic view 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]

 Reference Signs List 1 fixed platen 2 movable platen 4 toggle support 6 single toggle mechanism (toggle mechanism) 7 tie bar 8 mold clamping cylinder 9 piston 8a, 8b oil chamber

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-175127 (JP, A) JP-A-63-179723 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/64-45/68 B29C 33/20-33/24 B22D 17/26

Claims (2)

(57) [Claims] [1 claim] (a) a stationary platen is disposed between the (b) and said stationary platen facing the allowed to toggle support disposed, (c) the stationary platen and the toggle support, along the tie bars a movable platen for advancing and retracting Te, (d) is disposed between the toggle support and the movable platen, a toggle mechanism that is allowed actuated by a motor, (e) have one of the fixed platen and the toggle support <br / > Zureka disposed between one and the tie bars Rutotomo
In a mold clamping cylinder oil chamber is formed on both sides of the piston, in particular for selectively supplying and discharging oil to (f) above the oil chamber
Therefore, mold tension is applied by applying a tensile force to the tie bar.
A mold clamping apparatus for an electric injection molding machine and having a supply and discharge means for performing mold opening. [2 claim] (a) a stationary platen is disposed between the (b) and said stationary platen facing the allowed to toggle support disposed, (c) the stationary platen and the toggle support, along the tie bars a movable platen for advancing and retracting Te, (d) is disposed between the toggle support and the movable platen, a toggle mechanism that is allowed actuated by a motor, (e) have one of the fixed platen and the toggle support <br / > Zureka disposed between one and the tie bars Rutotomo
A small-diameter rod on the tie-bar side of the piston.
The first oil chamber is further provided on the tie bar side of the rod with the piston
The second oil chamber is on the tie bar side of the
A third mold clamping cylinder oil chamber is formed of, as well as organic and supply and discharge means for selectively supplying and discharging oil to (f) the first to third oil chamber, (g) the pressure receiving area of the second oil chamber, the first, the third oil chamber mold clamping apparatus for an electric injection molding machine, characterized in that it is greater than set pressure receiving area of.