JP2673814B2 - Molding device for injection molding machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device of an injection molding machine, and more particularly to a mold clamping mechanism thereof.

A so-called conductive injection molding machine using a servo motor can finely control the mechanism of each part to perform precise molding, but the mold clamping mechanism uses an inner winding toggle mechanism, or It had a structure in which the movable platen (mold clamping plate) was pressed directly with a ball screw.

However, the inward winding toggle type mold clamping mechanism has the feature that a large mold clamping force can be obtained with a small mold clamping motor (electric motor, the same applies below), but it is difficult to make the mechanism section compact and In order to avoid mutual interference, the machine tends to be large, and since the end of the movable platen is pushed, the center of the mold is slightly raised, but there is the disadvantage that burrs easily occur in the center of the molded product. In addition, the direct-acting type clamping mechanism that directly presses with a ball screw is compact and does not easily generate burrs in the center, but since it does not have a force amplifying device by a link, it is huge and expensive compared to the clamping force. Has the disadvantage of requiring a motor for use.

SUMMARY OF THE INVENTION The present invention uses a relatively small mold clamping motor, and
An object of the present invention is to provide a mold clamping device having a compact structure.

Means for Solving the Problems A mold clamping device has a structure in which a rear platen and a fixed platen are connected by a tie rod, and a movable platen is provided between both platens so as to be capable of parallel translation using the tie rod as a guide.

A toggle link mechanism is configured by movably connecting both ends of two refractable links provided with a rotatable connecting portion in the middle between the rear platen and the movable platen.

A screw mechanism is provided between the intermediate connecting portions of the toggle link mechanism.

The screw mechanism has a structure in which a ball nut is fixed to one of the connecting portions and a mold clamping motor is fixed to the other, and a ball screw connected to the output shaft of the motor is screwed into the ball nut.

The toggle link mechanism formed between the working rear platen and the movable platen converts the output of the mold clamping motor into mold clamping force.

The screw mechanism moves the connecting portion to bend the link and transmits the output of the mold clamping motor to the toggle link mechanism.

Embodiment FIG. 1 shows a mold clamping device 1 in an injection molding machine, in which a fixed platen 3, a rear platen 4 and a movable platen 5 are arranged in parallel on a machine frame 2 of a molding machine body, and a fixed platen 3 is provided.
Is fixed to the machine frame 2, and the rear platen 4 is configured to be slidable over a slight distance on the machine frame 2 for adjusting the mold thickness, which will not be described here.

The fixed platen 3 and the rear platen 4 are connected by four tie rods 6, and the movable platen 5 is fitted to the tie rods 6 and is located between the platens 3 and 4,
It is possible to slide with the guide as a guide.

The rear platen 4 and the movable platen 5 are connected by a toggle link mechanism 7, and the link mechanism 7 includes a screw mechanism 8.

The toggle link mechanism 7 has two parallel links 10 and 10 'which are bendable by providing a rotatable connecting portion 9 in the middle.
Both ends of each link 10, 10 'are composed of a rear platen 4
Is rotatably connected to the front surface of the movable platen 5.

In this embodiment, the links 10 and 10 'are arranged vertically close to each other with the pressing center line m of the mold clamping device 1 (the center line of the mold clamping force acting on the mold) sandwiched therebetween, and both ends of the links 10 and 10' are arranged in the rear platen 4 described above. Is connected to the center of the front surface of the movable platen 5 and the rear surface of the movable platen 5. Each of the links 10 and 10 'is formed by pivotally connecting one ends of two partial links a and b having the same length to the connecting portion 9.

The screw mechanism 8 includes a ball nut 11, a ball screw 12, and a mold clamping motor 13. The ball nut 11 is vertically fixed to the connecting portion 9 of the one link 10 with a fixing belt as shown in FIG. 3, and the mold clamping motor 13 is connected to the connecting portion 9'of the other link 10 'at the fourth position. It is attached with fixing bolts as shown.

The ball screw 12 is connected to an output shaft 14 of a mold clamping motor 13 using a joint 15 and is rotatably supported by a connecting portion 9 '.

Therefore, the screw mechanism 8 in which the upper and lower connecting portions 9 and 9'are combined is arranged orthogonal to the pressing center line m when viewed from the front.

In the molding cycle of the injection molding machine, when a mold opening command is issued by the control device of the injection molding machine, the mold clamping motor 13 is driven from the mold clamping state shown in FIG. 1 to move the ball screw 12 in one direction. It is rotated and the distance between the connecting portions 9, 9'in the upper and lower links 10, 10 'is expanded via the ball nut 11. Therefore, the links 10 and 10 'in the toggle link mechanism 7 are both bent synchronously outwardly, and the movable platen 5 is drawn to the rear platen 4 side to open the mold as shown in FIG. In this case, the screw mechanism 8 moves together with the movable platen 5 in the same direction as the links 10 and 10 'are bent.

As shown in FIG. 2, assuming that the lengths of the partial links a and b are r and r ′ and the inclination angle with respect to the pressing center line m is θ, the moving distance D of the movable platen 5 with respect to the fixed platen 3 and the ball nut 11 are shown. The distance E on the ball screw 12 is roughly calculated as D = (r + r '). Multidot. (1-cos .theta.) E = sin .theta. (R + r').

This is because if the lengths of the partial links a and b are both set to 650 mm and the required mold clamping stroke (that is, the maximum value of D) is set to 250 mm, the maximum inclination (θ =) of each partial link a and b is 35.
~ 36 °, the required effective length (E =) of the ball screw 12 is
It means about 740-750 mm.

When the motor 13 is rotated in the opposite direction from the above in response to a mold clamping command from the controller in the mold opening completion state shown in FIG. 2, the upper and lower connecting parts 9, 9'via the ball nut 11 and the ball screw 12.
The interval of is reduced. Because of this, the link 1 was refracted
0 and 10 'are extended, and the toggle link mechanism 7 presses the movable platen 5 toward the fixed platen 3 side to perform mold clamping as shown in FIG.

The output of the mold clamping motor 13 acting through the ball screw 12 at a substantially right angle with respect to the pressing center line m is converted into a mold clamping force in the pressing center line m direction by the toggle link mechanism 7.
The mold clamping force increases as the angle formed by the partial links a and b increases, and becomes close to the required mold clamping force near the completion of mold clamping.

In this case, since the refraction structure of the toggle link mechanism 7 is relatively simple, there is little interference between the links during operation. When the links 10, 10 'are bent by expanding the distance between the two connecting parts 9, 9'of the toggle link mechanism 7 as in the embodiment, the refracting directions of the links 10, 10' are outward and the links 10, 1 '.
Interference between 0'can be avoided.

Further, in this embodiment, since the toggle link mechanism 7 presses the central portion of the movable platen 5 at one end of each link 10, 10 ', the floating deformation of the central portion caused by pressing the peripheral portion of the movable platen 5 is prevented. No burrs are produced on the molded product.

It should be noted that the links 10 and 10 'are arranged parallel to each other with a sufficient distance, unlike the above embodiment, as shown in FIG. 5, and conversely, the links 10 and 10' are bent by the screw mechanism 7. It is also possible to configure the mold opening operation when it is operated.

In the above embodiment, the link 10 in the toggle link mechanism 7 is used.
Although two are provided above and below, two may be provided on the left and right, or three or more. However, when the number of the links 10 is three or more, generally, a plurality of the links 10 are arranged in parallel, the intermediate connecting portion 9 of each link 10 is commonly configured and divided into two sets. The two connecting portions 9 and 9'are connected by the screw mechanism 8 and each set is regarded as one link.

The lengths of the links 10 and 10 'need to be the same as a whole, but the lengths do not necessarily have to be the same due to the relationship between the partial links a and the partial links b constituting each.
Also, if the links 10 and 10 'are lengthened, the required mold clamping stroke can be obtained with a small inclination angle (θ) of the partial links a and b, but the overall mold clamping device becomes longer and the rigidity of the link itself is a problem. If it is made smaller, the inclination angle must be made larger, and the component force in the direction perpendicular to the pressing center line m becomes larger, so that the tie rod 6 of the movable platen 5 becomes larger.
There is a tendency for movements along the to not be performed smoothly.

EFFECTS OF THE INVENTION Since the screw mechanism for driving the toggle link mechanism is arranged in the direction perpendicular to the pressing center line, the mold clamping motor does not project to the rear part of the rear platen unlike the conventional case, and the toggle link mechanism is linked. Since the structure can be relatively simple without any interference between them, the mold clamping device can be made compact.

Connect the connection part in the middle of each link that constitutes the toggle link mechanism with a screw mechanism consisting of a ball nut and a ball screw,
Since this is driven by the mold clamping motor fixed to one of the connecting portions, a large mold clamping force can be obtained with a small mold clamping motor.

[Brief description of the drawings]

FIG. 1 is a front view at the time of mold clamping, FIG. 2 is a front view at the time of mold opening, FIG. 3 is a sectional view of an essential part, FIG. FIG. 1 ... Mold clamping device, 2 ... Main machine frame, 3 ... Fixed platen, 4 ... Rear platen, 5 ... Movable platen, 6 ...
Tie rod, 7 ... Toggle link mechanism, 8 ... Screw mechanism, 9 ... Connecting part, 10 ... Link, 11 ... Ball nut, 12 ... Ball screw, 13 ... Mold clamping motor, 14 ... Output shaft , 15 …… Joint.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-119215 (JP, A) JP 1-135619 (JP, A)

Claims (2)

(57) [Claims] 1. A movable platen is provided between a rear platen and a fixed platen joined by a tie rod so that the movable platen can move in parallel with the tie rod as a guide, and a rotatable connecting portion is provided in the middle between the rear platen and the movable platen to bend the platen. A toggle link mechanism is configured by rotatably connecting both ends of the two possible links to both platens, and between the two connecting portions of the toggle link mechanism, one of the connecting portions has a ball nut on the other. A mold clamping device for an injection molding machine, comprising a screw mechanism formed by fixing a mold clamping motor and screwing a ball screw connected to an output shaft of the motor into the ball nut. 2. The mold clamping device for an injection molding machine according to claim 1, wherein the link is bent by expanding the distance between the two common connecting portions.