JP2607665B2 - Mold clamping device of injection molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold clamping device for an injection molding machine, and more particularly to an injection molding machine capable of improving operation stability and improving the quality of a molded product. The present invention relates to a mold clamping device.

(Prior Art) Conventionally, a molding material heated and fluidized in a heating cylinder is injected into a mold by high pressure, cooled and solidified or cured therein, and then the mold is opened to take out a molded product. An injection molding machine as shown in FIG. 2 is provided (see Japanese Patent Application Laid-Open No. 63-179723).

That is, a mold clamping device 2 and an injection device 3 are installed on a machine base 1, and the mold clamping device 2 includes a fixed platen 4 and a movable platen 5, and a mold clamping cylinder 6 includes a tie bar 7.
When the movable platen 5 is reciprocated along the
And the movable mold 9 come and go.

Further, the injection device 3 has a nozzle 11 for heating and melting the molding material, that is, the resin in the hopper 10, and reciprocatingly moves the nozzle. The molten resin is injected from the nozzle 11 into the mold concave portions 8a, 9a. Is done. On the other hand, the molded article drops from the discharge port 12 to the lower side of the machine base 1 and is discharged.

In the injection molding machine as described above, the movable mold 9 reciprocates each time molding is performed, and comes into contact with and separates from the fixed mold 8 opposed thereto, so that the movable mold 9 is reciprocated at high speed. Is important in improving molding efficiency.

Therefore, the mold clamping cylinder 6 is provided to reciprocate the movable mold 9 and increase the force of pressing the fixed mold 8, that is, the mold clamping force.

By the way, in the mold clamping device 2, the mold clamping force is generated by the mold clamping cylinder 6, but is driven by an electric servomotor in order to improve the response in controlling. Is provided. In a motor driven by an electric servomotor, a ball screw and a movable platen are directly connected to each other, and the movable screw is moved by rotating the ball screw by the electric servomotor.

Also, the toggle mechanism and the ball screw are connected,
In some cases, the movable platen 5 is moved by rotating a ball screw by an electric servomotor to expand and contract a toggle.

Further, there is a type in which a movable platen 5 is moved by directly driving a toggle mechanism by an electric servomotor.

(Problems to be Solved by the Invention) However, in the above-described mold clamping device of the injection molding machine, when the rotation of the ball screw moves the linearly movable platen, an excessive load is applied to the ball screw to shorten the life. There is. In the case where the toggle mechanism and the ball screw are connected, and in the case where the toggle mechanism is directly driven by an electric servomotor, the tie bar 7 is forcibly extended at the time of the mold clamping in which the mold clamping force fluctuates, and the bush is stressed. In addition to this, the mold may be shocked when the mold is opened.

SUMMARY OF THE INVENTION The present invention solves the above-described problems and prevents the mold clamping force from fluctuating at the time of mold clamping, and provides a shock to the mold when mold clamping is completed and mold opening is started. An object of the present invention is to provide a mold clamping device for an injection molding machine.

(Means for Solving the Problems) For this purpose, the present invention provides a fixed platen that supports a fixed mold, a movable platen that supports the movable mold so as to face the fixed platen and moves the two molds toward and away from each other. In the mold clamping device of an injection molding machine having a drive servomotor, a toggle mechanism driven and expanded and contracted by the drive servomotor is provided, and a recess is provided in one of the toggle mechanism and the movable platen and the other is provided. A deformed cylinder is formed, and a working fluid is sealed in a space defined by the two.

In the space, an auxiliary piston connected to the mold clamping force adjusting means and having a smaller diameter than the odd-shaped cylinder is provided.

Further, the concave portion and the deformed cylinder may be provided between a toggle mechanism and a toggle support that supports the toggle mechanism.

(Operation) According to the present invention, a recess is formed in one of a toggle mechanism and a movable platen that are driven and extended by a driving servomotor.
On the other hand, a deformed cylinder is formed to seal the working fluid in a space defined by the two, and an auxiliary piston connected to the mold clamping force adjusting means and having a smaller diameter than the deformed cylinder is provided in the space. Since it is provided, the pressure of the working fluid in the space can be increased or decreased by adjusting the mold clamping force adjusting means to reciprocate the auxiliary piston.

Therefore, the mold clamping force does not fluctuate while operating the mold clamping force adjusting means.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a mold clamping device of an injection molding machine according to the present invention.

In the figure, a mold clamping device 21 includes a fixed platen 22 and a movable platen 23. When a toggle mechanism 24 for mold clamping reciprocates the movable platen 23 along a tie bar 25, a fixed mold 26 and a movable mold The mold 27 comes into contact with and separates from the mold 27.

The toggle mechanism 24 includes toggles 29 and 30 that are swingably connected to each other, and a driving servomotor 32 fixed to a toggle support 31. The drive servo motor 32
The shaft is connected to a toggle 29, and by rotating it, the toggle mechanism 24 extends when the mold is closed and contracts when the mold is opened.

A concave portion 33 is formed on a side of the movable platen 23 where the movable mold 27 is not provided, and a deformed cylinder 34 is provided so as to slide in the concave portion 33. The toggle cylinder 30 has one end of the odd-shaped cylinder 34 swingably supported. A space 49 is formed between the concave portion 33 and the deformed cylinder 34, and a working fluid 35 such as a viscous and flame-retardant oil is accommodated therein.
Is transmitted to the movable platen 23.

The inside of the concave portion 33 is connected to an air breather 37 through a groove 36 extending from the side wall to the outer periphery.
It is possible to remove air from 37 and to replenish the working fluid 35.

The movable platen 23 is provided with a stopper 38 for preventing the deformed cylinder 34 from coming off when the mold is opened.

In the mold clamping device having the above-described configuration, when the mold closing process is completed and the toggles 29 and 30 are almost fully extended, the stopper fixed to the end of one of the toggles 29
When 39 abuts on the other toggle 30, the toggle mechanism 24
Stops, and both toggles 29 and 30 become horizontal.

Subsequently, the position of the toggle support 31 is adjusted, and the movable mold 27 and the fixed mold 26 are brought into a state immediately before the close contact. At this time, if there is any foreign matter between the two dies 26 and 27, the pressure of the working fluid 35 rises, and the pressure sensor 41 detects this and prevents the next mold clamping step from being started.

If there is no foreign matter, the pressure of the working fluid 35 does not increase more than the movement resistance and the next mold clamping process is started.
Is activated.

The mold clamping force adjusting means 40 includes an auxiliary cylinder 42 formed integrally with or separate from the movable platen 23, and an auxiliary piston 43 reciprocating in the auxiliary cylinder 42. A ball screw 44 is formed at one end of the auxiliary piston 43, and a screw that meshes with the ball screw 44 is formed on the inner surface of the pulley 45. Then, the ball screw is rotated by the rotation transmitted from the step-up motor 48 via the pulleys 45 and 46 and the timing belt 47.
44 reciprocates the auxiliary piston 43.

By actuating the mold clamping force adjusting means 40 having the above configuration, the pressure of the working fluid 35 is increased, and the movable platen 23 moves to the right in the drawing to perform mold clamping.

Here, the pressure receiving area of the auxiliary piston 43 constituting the mold clamping force adjusting means 40 is sufficiently small, and the force received by the ball screw 44 is also about one tenth of the ordinary mold clamping force, so that its life is prolonged. .

In addition, an ejector 51 for dropping the cooled and solidified molded product is provided in the mold portion of the movable mold 27. The ejector 51 moves forward and backward when the ball screw 52 moves. The rotation of an ejector motor 56 is transmitted to the ball screw 52 via pulleys 53 and 54 and a timing belt 55.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the gist of the present invention.
They are not excluded from the scope of the present invention.

(Effects of the Invention) As described above, according to the present invention, a toggle mechanism that is driven and extended by a driving servomotor and a movable platen are formed by forming a concave portion on one side and a deformed cylinder on the other side. A working fluid is sealed in the space, and an auxiliary piston connected to the mold clamping force adjusting means and having a diameter smaller than that of the deformed cylinder is disposed in the space, so that the mold clamping force adjusting means is adjusted. The pressure of the working fluid in the cylinder can be increased or decreased by reciprocating the auxiliary piston.

Therefore, the mold clamping force does not fluctuate while the mold clamping force adjusting means is operated, so that the bush does not rattle, and it is possible to prevent the mold from being shocked when the mold is opened. .

Also, since the clamping force can be easily controlled,
A degassing effect and a compression effect can be easily obtained, and prevention of "sink" can be achieved.

Furthermore, since a complicated hydraulic structure is not used and the pressure applied to the auxiliary piston is low, oil leakage hardly occurs and an oil cooler is not required.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold clamping device of an injection molding machine according to the present invention.
FIG. 1 shows a conventional injection molding machine. 1 ... machine stand, 2,21 ... mold clamping device, 3 ... injection device, 4,22
…… Fixed platen, 5,23 …… Movable platen, 6 …… Cylinder for mold clamping, 7,25 …… Tie bar, 8,26 …… Fixed mold, 9,
27 …… Movable mold, 10 …… Hopper, 24 …… Toggle mechanism,
29, 30… Toggle, 31… Toggle support, 32… Drive servo motor, 33… Recess, 34… Deformed cylinder, 35
... working fluid, 38, 39 ... stopper, 40 ... mold clamping force adjusting means, 47, 55 ... timing belt, 48 ... step-up motor, 49 ... space, 56 ... ejector motor.

Claims (2)

(57) [Claims] 1. A mold clamping apparatus for an injection molding machine, comprising: a fixed platen for supporting a fixed mold; and a movable platen for supporting the movable mold so as to face the fixed platen and moving the two molds toward and away from each other. (A) a drive servomotor, (b) a toggle mechanism that is extended and contracted by the drive servomotor, and (c) a concave portion is formed in one of the toggle mechanism and the movable platen, and a deformed cylinder is formed in the other. The working fluid is sealed in the space defined by the two, and (d) an auxiliary piston connected to the mold clamping force adjusting means and having a smaller diameter than the deformed cylinder is disposed in the space. Mold clamping device for injection molding machines. 2. A mold clamping apparatus for an injection molding machine, comprising: a fixed platen supporting a fixed mold; and a movable platen supporting the movable mold so as to face the fixed platen and moving the two molds apart from each other. (A) a drive servomotor; (b) a toggle mechanism driven and expanded and contracted by the drive servomotor; (c) a recess in one of the toggle mechanism and a toggle support supporting the toggle mechanism; A cylinder is formed, and a working fluid is sealed in a space defined by the two. (D) In the space, an auxiliary piston connected to mold clamping force adjusting means and having a smaller diameter than the deformed cylinder is disposed. A mold clamping device for an injection molding machine, which is provided.