JPH1128747A - Clamping device of molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable smooth attainment of a mold opening-closing operation of high speed and low pressure and a clamping operation of high pressure, in a clamping device which is so designed as to drive a movable die plate back and forth by a servomotor without using a toggle link mechanism or a crank mechanism as an intermediary. SOLUTION: In a molding machine equipped with a ball screw shaft 6 of which the opposite ends are held rotatably by a fixed die plate 1 fitted with a fixed-side mold 2 and by a holding plate 5, a movable die plate 3 which is so arranged as to be movable back and forth along the ball screw shaft 6 and is fitted with a movable-side mold 4 and a nut body 11 which is held by the movable die plate 3 so that it can only rotate and which is screwed on the ball screw shaft 6, this clamping device is provided with a servomotor 13 for driving the nut body which drives the nut body 11 to rotate and a servomotor 17 for driving the ball screw shaft which drives the ball screw shaft 6 to rotate.

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 a molding machine such as an injection molding machine or a die casting machine.
The present invention relates to a mold clamping device for a molding machine using a servomotor (electric servomotor) as a drive source.

[0002]

2. Related Background Art As a mold clamping device of a molding machine using a servomotor as a driving force for clamping, a toggle type clamping device using a toggle link mechanism is well known. In this toggle-type mold clamping device, a large mold clamping force is obtained by utilizing the expansion rate of the force by the toggle link mechanism, and in a dead point state where the toggle link mechanism is completely stretched, the servo is closed. Even if the power supply to the motor is cut off, the mold clamping state can be maintained.

However, in the toggle-type mold clamping device, the existence of the above-mentioned toggle link mechanism is a major hindrance for simplifying the mold clamping mechanism of the molding machine. There is also a problem that the degree of freedom of the arrangement of the eject mechanism is lost.

On the other hand, a ball screw shaft is suspended between a fixed die plate and a holding plate, and a nut body screwed to the ball screw shaft is attached to the movable die plate, and a servomotor mounted on the movable die plate. In the mold clamping device in which the movable die plate is driven to move forward and backward by rotating the nut body, the mold clamping mechanism can be simplified, and the degree of freedom of arrangement of the eject mechanism mounted on the movable die plate can be increased. . The mold clamping device having such a configuration is, for example, a Japanese Patent Publication No.
No. 42814 and Japanese Patent Publication No. 5-56248.

[0005]

In the prior art disclosed in the above-mentioned prior application, a plurality of nut bodies are rotationally driven by one servomotor, and the mold opening / closing operation and the mold are performed by this servomotor. Since the tightening force is generated and maintained, increasing the reduction ratio of the rotation transmission system from the servo motor to the nut body to obtain a large torque (high pressure)
High-speed and low-pressure mold opening and closing operations have been hindered.On the other hand, if the reduction ratio of the rotation transmission system from the servomotor to the nut body is reduced to achieve high-speed and low-pressure, high-pressure mold clamping operations are hindered. Come. In addition, since a plurality of nut bodies are rotationally driven by one servomotor, a large and powerful servomotor is required, resulting in an expensive servomotor. There was a problem.

[0006] The present invention has been made in view of the above points,
The purpose is to achieve high-speed and low-pressure mold opening / closing operation and high-pressure mold clamping in a mold clamping device in which the movable die plate is driven back and forth by a servomotor without going through a toggle link mechanism or a crank mechanism. Operation is reasonably achievable. It is another object of the present invention to reduce the total cost by using a small and inexpensive servomotor.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a fixed die plate and a holding plate to which a fixed mold is attached, a ball screw shaft rotatably held at both ends thereof, and the ball screw. A movable die plate which is disposed so as to be able to move forward and backward along the axis and has a movable die attached thereto, and a nut body which is held rotatably only on the movable die plate and is screwed to the ball screw shaft. In the mold clamping device of the molding machine provided, a nut body driving servomotor for rotatingly driving the nut body and a ball screw shaft driving servomotor for rotatingly driving the ball screw shaft are provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a mold clamping device of an injection molding machine according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a fixed die plate to which a fixed mold 2 is attached, 3 denotes a movable die plate to which a movable mold 4 is attached, and 5 denotes a holding plate. Reference numeral 6 denotes a ball screw shaft, both ends of which are rotatably supported by the fixed die plate 1 and the holding plate 5 via bearings 7 and 8, respectively. At two corners in a relationship, they are arranged at 180-degree intervals. Reference numeral 9 denotes a guide bar, both ends of which are fixed to the fixed die plate 1 and the holding plate 5 by mounting nuts 10, and are disposed at 180 ° intervals at the remaining two corners of the four corners of each plate 1,5. Has been established. The ball screw shaft 6 and the guide bar 9 pass through four corners of the movable die plate 3, and the movable die plate 3 can move forward and backward along the ball screw shaft 6 and the guide bar 9.

Reference numeral 11 denotes a nut body screwed to each ball screw shaft 6, which is rotatably held on the movable die plate 3 via a bearing (not shown).
2 are integrally fixed. Numeral 13 denotes a nut body driving servo motor mounted on the movable die plate 3 corresponding to each nut body 11. A drive pulley 14 fixed to an output shaft of the motor 13 is connected to a nut body via a timing belt 15. 11 is connected to the driven pulley 12 by a belt. The nut body driving servomotors 13 are driven and controlled in synchronization with each other.

Reference numeral 16 denotes a driven pulley fixed to the end of each ball screw shaft 6. Reference numeral 17 denotes a ball screw shaft driving servomotor mounted on the holding plate 5 corresponding to each ball screw shaft 6. Drive pulley 1 fixed to shaft
8 is connected to the ball screw shaft 6 via the timing belt 19.
The belt is connected to the driven pulley 16. The servomotors 17 for driving the ball screw shafts are also driven and controlled in synchronization with each other.

FIG. 2A shows the holding plate 5 described above.
FIG. 6 is a diagram showing a relationship between a ball screw shaft driving servomotor 17 mounted on the motor and a driven pulley 16 of the ball screw shaft 6;
FIG. 2B is a diagram illustrating a relationship between the nut body driving servomotor 13 mounted on the movable die plate 3 and the driven pulley 12 of the nut body 11.

As shown in FIGS. 1 and 2, the diameter of the driven pulley 12 of the nut body 11 is the same as that of the driven pulley 16 of the ball screw shaft 6.
, Thereby reducing the reduction ratio of the rotation transmission system from the nut body driving servomotor 13 to the nut body 11 and the rotation transmission system from the ball screw shaft driving servomotor 17 to the ball screw shaft 6. It is set to be larger than the reduction ratio. In the present embodiment, the servomotor 17 for driving the ball screw shaft is used for opening and closing the mold, and the servomotor 13 for driving the nut body is used for generating the mold clamping force.

Next, the operation of the present embodiment having the above-described configuration will be described. In the mold open state, the movable die plate 3 is at a retreat position closer to the left than the position in FIG. 1, and the movable mold 4 is separated from the fixed mold 2 by a predetermined amount. In this mold open state, when the mold closing start timing is reached, the servo amplifiers of the ball screw shaft driving servo motors 17 synchronize the respective ball screw shaft driving servo motors 17 by a command from a system controller (not shown). It is driven to rotate in the direction. In addition, according to an instruction from a system controller (not shown), the servo amplifiers of the respective nut body driving servomotors 13 are controlled such that the respective nut body driving servomotors 13 maintain the current stop position, and the respective nut bodies 11 are The rotation is disabled (the rotation of each nut body 11 is locked).

Thus, the rotation of the ball screw shaft driving servomotor 17 is transmitted to the ball screw shaft 6 via the driving pulley 18, the timing belt 19, and the driven pulley 16, and the ball screw shaft 6 rotates in a predetermined direction. Since the rotation of the nut body 11 is locked, the ball screw shaft 6
As a result, the nut body 11 is driven forward in the rightward direction in FIG. 1, whereby the movable die plate 3 moves forward integrally with the nut body 11.

The servomotor 17 for driving the ball screw shaft is
The movable mold 4 is driven to rotate until it touches the fixed mold 2, and when the mold touch is detected, the rotation of the ball screw shaft driving servomotor 17 is stopped by an instruction from a system controller (not shown). At the same time, the servomotors 17 for driving the respective ball screw shafts are controlled so as to maintain the current stop position, and the respective ball screw shafts 6 are set in a non-rotatable state (the rotations of the respective ball screw shafts 6 are locked).
At the same time, each nut body driving servomotor 13 is synchronously rotated and driven in a predetermined direction by a servo amplifier of each nut body driving servomotor 13 in response to an instruction from a system controller (not shown).

Thus, the rotation of the nut body driving servomotor 13 is controlled by the driving pulley 14 and the timing belt 1.
5, transmitted to the nut body 11 via the driven pulley 12, and the nut body 11 rotates slightly in a predetermined direction. Since the rotation of the ball screw shaft 6 is locked, the nut body 11 is driven in the rightward direction in FIG. 1, whereby the movable die plate 3 receives the forward driving force in the rightward direction to generate a mold clamping force. . This state is maintained until the mold opening start timing.

At the time of opening the mold, each ball screw shaft driving servomotor 17 is rotated in the opposite direction by the servo amplifier of each ball screw shaft driving servomotor 17 in synchronization with the servo amplifier of each ball screw shaft driving servo 17 according to an instruction from a system controller (not shown). Driven. Further, in accordance with an instruction from a system controller (not shown), the rotation of each nut body 11 is locked by the servomotor 13 for driving each nut body. Thereby, the rotation of the servomotor 17 for driving the ball screw shaft is transmitted to the ball screw shaft 6, and the rotation of the ball screw shaft 6
The nut body 11 is driven backward in the leftward direction in FIG. 1, whereby the movable die plate 3 is moved backward integrally with the nut body 11.

As described above, in the present embodiment, the nut body driving servomotor 13 for driving the nut body 11 to rotate and the ball screw shaft driving servomotor 17 for driving the ball screw 6 to rotate are provided. 13 is made larger than the reduction ratio of the rotation transmission system of the ball screw shaft driving servomotor 17 by the ball screw shaft driving servomotor 17, the nut body driving servomotor 13 generates a mold clamping force, and the ball screw shaft driving servo. Since the mold opening / closing operation is performed by the motor 17, a high-pressure mold clamping operation and a high-speed / low-pressure mold opening / closing operation can be simultaneously and comfortably achieved. Further, since the ball screw shaft driving servomotor 17 and the nut body driving servomotor 13 are provided in association with the ball screw shaft 6 and the nut body 11, respectively, each servomotor can be made small and inexpensive. Even if the number of small servomotors is increased, the total cost can be reduced as compared with a case where the same power is obtained by a single servomotor.

FIG. 3 is a diagram showing a main part of an injection molding machine according to a second embodiment of the present invention. FIG. 3A shows a servomotor 17 for driving a ball screw shaft mounted on a holding plate 5.
FIG. 4B shows the relationship between the nut body driving servomotor 13 mounted on the movable die plate 3 and the driven pulley 12 of the nut body 11. Is shown.

In the present embodiment, four ball screw shafts 6 are provided between the fixed die plate 1 and the holding plate 5, and both ends of each ball screw shaft 6 are connected to the fixed die plate 1 and the holding plate via bearings. 5 are rotatably supported. That is, ball screw shafts 6 are arranged at four corners of the fixed die plate 1 and the holding plate 5 at intervals of 90 degrees. Then, the four nut bodies 11 screwed to the four ball screw shafts 6 are held by the movable die plate 3 via bearings so as to be rotatable only. A body drive servomotor 13 is mounted on the movable die plate 3, and a ball screw shaft drive servomotor 17 is mounted on the holding plate 5 corresponding to each ball screw shaft 6.

The other configuration and operation of this embodiment are the same as those of the first embodiment. However, in this embodiment, the power obtained by adding four nut body driving servomotors 13 and the four Since the combined power of the servomotor 17 for driving the ball screw shaft is output, a higher output mold clamping device can be realized.

In the above-described embodiment, the servomotor 13 for driving the nut body is used for generating the mold clamping force, and the servomotor 17 for driving the ball screw shaft is used for opening and closing the mold.
By changing the reduction ratio of the transmission system of each motor, it is perfectly acceptable to use the servomotor 17 for driving the ball screw shaft for generating the mold clamping force and the servomotor 13 for driving the nut body for opening and closing the mold.

In the above-described embodiment, the ball screw shaft driving servomotor 17 is mounted on the holding plate 5. However, the ball screw shaft driving servomotor 1 is mounted on the holding plate 5.
7 may be mounted on the solid die plate 1.

In the above-described embodiment, either the nut body driving servomotor 13 or the ball screw shaft driving servomotor 17 is selectively driven to rotate. The nut body driving servomotor 13 and the ball screw shaft driving servomotor 17 may be simultaneously driven to rotate. For example, at the end of the mold closing stroke by the ball screw shaft driving servo motor 17, the nut body driving servo motor 13 is simultaneously driven in the direction in which the brake is applied, whereby the moving die plate 3 moves forward at the end of the mold closing stroke. The operation may be suddenly braked.

[0025]

As described above, according to the present invention, a high-speed, low-pressure mold clamping apparatus is provided in which a movable die plate is driven forward and backward by a servomotor without a toggle link mechanism or a crank mechanism. The opening / closing operation and the high-pressure mold clamping operation can be easily and simultaneously achieved. Further, by using a small and inexpensive servomotor, the total cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a mold clamping device of an injection molding machine according to a first embodiment of the present invention.

FIG. 2A is an explanatory diagram showing a relationship between a servomotor for driving a ball screw shaft mounted on a holding plate and a driven pulley of the ball screw shaft in the injection molding machine according to the first embodiment of the present invention; (B) is an explanatory view showing the relationship between the nut body driving servomotor mounted on the movable die plate and the driven pulley of the nut body in the injection molding machine according to the first embodiment of the present invention.

FIG. 3A is an explanatory view showing a relationship between a ball screw shaft driving servomotor mounted on a holding plate and a driven pulley of the ball screw shaft in an injection molding machine according to a second embodiment of the present invention; (B) is an explanatory view showing the relationship between the nut body driving servomotor mounted on the movable die plate and the driven pulley of the nut body in the injection molding machine according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 fixed die plate 2 fixed die 3 movable die plate 4 movable die 5 holding plate 6 ball screw shaft 7,8 bearing 9 guide bar 10 mounting nut 11 nut body 12 driven pulley 13 nut body driving servomotor 14 drive pulley 15 Timing belt 16 Driven pulley 17 Servo motor for driving ball screw shaft 18 Drive pulley 19 Timing belt

Claims (8)

[Claims] 1. A fixed die plate and a holding plate to which a fixed mold is attached, a ball screw shaft rotatably held at both ends thereof, and a movable member disposed so as to be able to move forward and backward along the ball screw shaft. A molding machine comprising: a movable die plate to which a side die is attached; and a nut body rotatably held by the movable die plate and screwed to the ball screw shaft. A mold clamping device for a molding machine, comprising: a body driving servomotor; and a ball screw shaft driving servomotor that rotationally drives the ball screw shaft. 2. The method according to claim 1, wherein the nut body driving servomotor is mounted on the movable die plate, and the ball screw shaft driving servomotor is mounted on the holding plate or the fixed die plate. Characteristic mold clamping device for molding machines. 3. A reduction ratio of a rotation transmission system from the nut body driving servomotor to the nut body and a reduction of a rotation transmission system from the ball screw shaft driving servomotor to the ball screw shaft. A mold clamping device for a molding machine, wherein the ratio is different. 4. The method according to claim 3, wherein one of the nut body driving servomotor and the ball screw shaft driving servomotor is used for opening and closing a mold, and the other is used for generating a mold clamping force. Characteristic mold clamping device for molding machines. 5. The ball screw shaft driving servo according to claim 4, wherein the rotation of the ball screw shaft is locked by the ball screw shaft driving servo motor when the nut body driving servo motor is driven to rotate. A mold clamping device for a molding machine, wherein the rotation of the nut body is locked by the nut body driving servomotor when the ball screw shaft is driven to rotate by a motor. 6. The mold clamping device for a molding machine according to claim 1, wherein the servomotor for driving the nut body and the servomotor for driving the ball screw shaft are driven to rotate simultaneously. 7. The ball screw shaft according to claim 1, wherein two of the ball screw shafts are separated by approximately 180 degrees, or 4
A mold clamping device for a molding machine, wherein books are disposed at approximately 90 degree intervals, and the nut body driving servomotor and the ball screw shaft driving servomotor are disposed corresponding to the respective ball screw shafts. . 8. The synchronous motor according to claim 7, wherein all of the plurality of nut body driving servomotors are synchronously rotationally controlled, and all of the plurality of ball screw shaft driving servomotors are synchronously rotationally controlled. A mold clamping device for a molding machine.