JP2000289066A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately obtain a molded article which requires a large mold clamping force. SOLUTION: Driving means for an injection apparatus 1 and a mold clamping apparatus 20 are properly used. i.e., when a screw is driven in the rotating direction to perform plasticization, a motor-driven servo motor is used and when it is driven in the axial direction to perform injection, a servo motor for injection is used. The mold clamping apparatus 20 is driven by means of a hydraulic piston cylinder unit 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device provided with a first driving means for driving a screw in a rotational direction and an axial direction, and a movable mold with a mold clamping direction and a mold opening with respect to a fixed mold. The present invention relates to an injection molding machine comprising a mold clamping device provided with a second driving means for driving in two directions.

[0002]

2. Description of the Related Art Both an electric injection molding machine and a hydraulic injection molding machine are well known, and generally comprise an injection device and a mold clamping device. The injection device of the electric injection molding machine is composed of a cylinder barrel, a screw provided in the cylinder barrel so as to be drivable in the rotation direction and the axial direction, and the screw is an electric servomotor for plasticizing and injection. It is designed to be driven. The mold clamping device includes a toggle mechanism for driving the movable platen to the fixed platen in the mold clamping direction or the mold opening direction, and this toggle mechanism is also driven by an electric servomotor. Therefore, the screw is rotated by the plasticizing electric servomotor to measure the injection material, the toggle mechanism is driven by the electric clamping servomotor to clamp the movable mold against the fixed mold, and The screw can be driven in the axial direction by the electric servomotor for injection and injected to obtain a molded product.

On the other hand, an injection device of a hydraulic injection molding machine also comprises a cylinder barrel, a screw provided in the cylinder barrel so as to be drivable in a rotating direction and an axial direction, and the screw is used for plasticization and injection. Is driven by a hydraulic rotary motor. The mold clamping device generally includes a piston / cylinder unit, and the movable plate is driven by the piston / cylinder unit on the fixed plate in a mold clamping direction or a mold opening direction.
Therefore, a molded article can be obtained in the same manner as in the electric injection molding machine.

[0004]

As described above, a molded article can be obtained by an electric injection molding machine or by a hydraulic injection molding machine, but it has advantages and disadvantages and is not always satisfactory. . That is, in the electric injection molding machine, the actuator, for example, the toggle mechanism is mechanically driven via the ball screw by the electric servomotor, so that the responsiveness is good, and the electric power is only when the toggle mechanism is driven. There is also an advantage that the power consumption is small because the power is only consumed and turned off when not driving. However, since there is no large ball screw for driving the toggle mechanism or a large-capacity electric servomotor in Japan, it cannot be used for a large injection molding machine having a mold clamping force of 850 tons or more. That is, it cannot sufficiently cope with molding requiring a large clamping force as compared with the injection volume. Examples of such a molding requiring a large mold clamping force include a molding example for molding a hollow body molded article proposed by the present applicant in large numbers. More specifically, in performing the molding method, a set of molds is used, and one mold is provided with a male mold and a female mold for forming one semi-hollow molded article. The other mold is provided with a female mold and a male mold for forming the other semi-hollow molded article. Therefore, in the primary molding, a pair of semi-hollow molded articles is molded using this one set of molds,
Then, in the secondary molding, one mold is slid with respect to the other mold so that the butted portions of the semi-hollow molded products are butted against each other, and then the molten resin is injected into the periphery of the butted surface to be integrated into a hollow body. A molded article can be obtained. The mold clamping force at the time of the primary molding requires approximately twice the mold clamping force at the time of the secondary molding, and a sufficient clamping force may not be obtained with a conventional electric injection molding machine. If the mold clamping force is insufficient, it causes burrs and lowers the quality of the molded product. As a solution to this problem, it is theoretically possible to solve this problem by using two or three ball screws and increasing the number of electric servomotors correspondingly. However, it is difficult to synchronize a plurality of ball screws. In reality, it is not realized because it is expensive.

On the other hand, a hydraulic injection molding machine can be manufactured with a large hydraulic piston / cylinder mechanism, and a hydraulic injection molding machine with a mold clamping force of 6,500 tons has been provided by a toggle mechanism in the past. . However, hydraulic oil has a drawback that it has compressibility and poor response or controllability. Further, although the temperature of the hydraulic oil increases with the passage of time, there is a problem that it is difficult to control the temperature.
If the temperature is not constant, the viscosity becomes unstable, and for example, the rotational speed of a hydraulic motor that drives the screw in the axial direction also becomes unstable. In this case, the injection speed is not constant, which may cause molding defects such as sink marks and weld defects.
The injection weight and the like also vary, and are not suitable for precision molding. Furthermore, even when an actuator such as a toggle mechanism is not driven, there is a problem that the power consumption increases because the hydraulic pump is operating. An object of the present invention is to provide an injection molding machine that solves the conventional problems as described above, and specifically, a molded product that requires a large clamping force, for example, but not limited to, It is an object of the present invention to provide an injection molding machine capable of obtaining a hollow molded article with high precision.

[0006]

In order to achieve the above object, an invention according to claim 1 includes an injection device having first driving means for driving a screw in a rotational direction and an axial direction;
An injection molding machine comprising a mold clamping device having a second driving means for driving a movable mold in a mold clamping direction and a mold opening direction with respect to a fixed mold, wherein the first driving means is electrically driven. From a rotary motor and said second drive means is a hydraulic piston
It consists of a cylinder unit. According to a second aspect of the present invention, there is provided an injection device including first driving means for driving a screw in a rotational direction and an axial direction, and a movable mold in a mold clamping direction and a mold opening direction with respect to a fixed mold. An injection molding machine comprising a mold clamping device provided with a second driving means for driving the first driving means and the driving means for moving the injection apparatus in the axial direction from an electric rotary motor, and The second
The driving means and the ejector device driving means are composed of a hydraulic piston / cylinder unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 taking a toggle type injection molding machine as an example. An injection device 1 according to the present embodiment includes a cylinder barrel 2, a screw provided in the cylinder barrel so as to be drivable in a rotating direction and an axial direction, and an electric servomotor for plasticizing for driving the screw in a rotating direction. 5. It comprises an injection electric servomotor 9 for driving the screw in the axial direction, that is, the injection direction. Between the plasticizing electric servomotor 5 and the screw shaft, gear units 3 and 4 are interposed as power transmitting means in the rotation direction, and between the injection electric servomotor 9 and the screw shaft, The gear devices 8 and 9 are interposed as power transmission means, and a ball screw mechanism 6 is interposed as means for converting the rotation direction to the axial direction. The injection device 1 configured as described above includes the base 1
The base 10 is mounted on a bed 11 so as to be movable in the axial direction. Therefore, the injection device 1 is movable in a direction in which the injection device 1 comes into contact with a mold clamping device 20 to be described later and in a direction in which the injection device 1 separates therefrom. A moving electric servomotor 12 for this purpose is attached to the bed 11.
Although not shown in the drawing, a screw mechanism 14 for changing the rotational motion into a linear motion is provided between the output shaft 13 of the moving electric servomotor 12 and the base 10. Is converted into the axial movement of the base 10.

The outer shape or main body of the toggle-type mold clamping device of the mold clamping device 20 is configured similarly to the conventional toggle-type mold clamping device. That is, a fixed board 21 fixed on the bed 11, a mold clamping housing 23 provided on the bed 11 at an interval from the fixed board 21 so as to be movable in the axial direction,
Four tie bars 24, 24,..., Four tie bars 24, 2 provided between the fixed platen 21 and the mold clamping housing 23.
The movable platen 22 is guided and moved in the axial direction by 4,..., A toggle mechanism 30 for driving the movable platen 22 in a mold closing direction or a mold opening direction, a mold clamping cylinder unit 40 for driving the toggle mechanism 30, and the like. I have.

One end of each of the tie bars 24, 24,... Is passed through through holes at four corners of the fixed board 21 and is fixed to the fixed board 21. The other ends of the tie bars 24, 24,.
It penetrates the four corners of the mold clamping housing 23 and extends to the outside. Then, outside the mold clamping housing 23,
Screws are formed on the tie bars 24, 24,..., And die thickness adjusting nuts 25, 25,.

As is well known in the art, the toggle mechanism 30 includes a pair of relatively long first links 31, 31, a pair of relatively short second links 32, 32, a pair of third links, a crosshead 33, and the like. I have. Then, the first links 31, 3
One end of the first link is pin-connected to the movable platen 22, and the other end is similarly pin-connected to one end of the second links 32,32. The other ends of the second links 32, 32 are similarly pinned to the mold clamping housing 23, and the ends of the third links are similarly pinned to the second links 32, 32 and the crosshead 33, respectively.

A through hole is formed at a substantially central portion of the mold clamping housing 23, and the piston rod 41 of the mold clamping cylinder unit 40 provided outside the mold clamping housing 23 passes through the through hole to allow the toggle mechanism 30 to pass therethrough. Are connected to the crosshead 33 of Therefore, the mold clamping cylinder unit 40
When the crosshead 33 is driven in the axial direction by the piston rod 41, the movable platen 22 is driven in the mold closing direction or the mold opening direction.

A fixed die K1 is mounted on the fixed platen 21 and a movable die K2 is mounted on the movable plate 22, as is well known in the art. The movable platen 22 is provided with an ejector cylinder 45 of an ejector device. . Mold clamping cylinder unit 4
The hydraulic device that supplies pressure oil to the zero and the ejector cylinder unit 45 includes a hydraulic pump 50, an electric rotary motor 52 that drives the hydraulic pump, an electromagnetic direction switching valve 52, and the like. The first of the electromagnetic directional switching valves 52
Port and the piston head 42 side of the mold clamping cylinder unit 40 are connected by a first pressure oil supply line 53, and the second port and the piston rod 42 side of the mold clamping cylinder unit 40 are connected to a second pressure oil supply line 54. Are connected to each other. Further, the piston head side of the ejector cylinder unit 45 and the third
Are connected by a third pressure oil supply line 55. The pressure oil supply line connecting the piston rod side of the ejector cylinder unit 45 and the port of the electromagnetic directional switching valve 52 is not shown in FIG. Also, relief valve,
The pressure reducing valve and the like are not shown in FIG. In FIG. 1, other symbols H indicate a hopper, and T indicates an oil tank.

Next, the operation of the above embodiment will be briefly described. While supplying injection material from hopper H,
The plasticizing electric servomotor 5 is started to rotationally drive the screw. Then, in the process of being sent forward of the cylinder barrel 2 with the rotation of the screw, the injection material is melted by heat applied from the outside of the cylinder barrel 2 and heat generated by frictional action, shear action, and the like due to the rotation of the screw. , And accumulated in front of the cylinder barrel 2.
The screw retracts due to the pressure of the accumulated injection material in the molten state or in combination with suckback. When a predetermined amount is accumulated, the plasticizing electric servomotor 5 is stopped. Thereby, the power consumption is suppressed. By switching the electromagnetic direction switching valve 52, the pressure oil is supplied to the side of the piston head 42 of the mold clamping cylinder unit 40. Then, the piston rod 41 is driven in the axial direction, and the movable plate 22 is clamped to the fixed plate 21 by the toggle mechanism 30. The base 10 is driven by the electric rotating motor 12 for movement, and the injection nozzle 2 ′ provided in front of the cylinder barrel 2 is touched to the fixed platen 21. Electric servo motor 9 for injection
To drive the screw in the injection direction. As a result, the injection material is injected and filled into the cavities of the molds K1 and K2. When filling is completed, the injection electric servomotor 9
Is stopped, and weighing is started by the plasticizing electric servomotor 5 for the next injection. After cooling and solidification, the electromagnetic directional control valve 52 is switched to switch the mold clamping cylinder unit 4.
The pressure oil is supplied to the side of the piston rod 43, and the pressure oil is also supplied to the piston head side of the ejector cylinder 45. Then, the movable platen 22 and therefore the movable mold K2
Is opened, and the molded product is ejected by the ejector pins of the ejector device. Hereinafter, molding is performed in the same manner.

In the above embodiment, the movable platen 22 is driven by a toggle mechanism. However, it is obvious that the movable plate 22 can be implemented by a direct pressure type in which a hydraulic cylinder is directly driven instead of the toggle mechanism. .

[0015]

As described above, according to the present invention, the first driving means for driving the screw in the rotational direction and the axial direction is constituted by the electric rotary motor, so that the responsiveness or controllability is good. Variations in injection pressure, injection speed, injection weight, etc. are small and stable, and a high quality molded product can be obtained. The second driving means for driving the movable mold in the mold closing direction and the mold opening direction with respect to the fixed mold is a hydraulic piston
Since it is composed of a cylinder unit, a large clamping force can be obtained. Therefore, according to the present invention, it is possible to obtain a molded product requiring a large mold clamping force with high accuracy, and it is possible to obtain an effect unique to the present invention, which cannot be expected from a conventional injection molding machine. Further, since the first drive means is constituted by an electric rotary motor, an effect of reducing power consumption can be obtained. According to the invention described in claim 2, the driving means for moving the injection device in the axial direction is the first driving means.
The drive means is composed of an electric rotary motor, and the ejector drive means is composed of a hydraulic piston / cylinder unit, like the drive means of the mold clamping device. Is further obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention in a partial cross section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Injection apparatus 2 Cylinder barrel 5 Electric servo motor for plasticization 9 Electric servo motor for injection 12 Electric servo motor for movement 20 Mold clamping device 30 Toggle mechanism 40 Mold clamping cylinder unit 45 Ejector cylinder unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junichi Chajima 1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima F-term in Japan Steel Works, Ltd. (reference) AM34 AM36 JA07 JC01 JC05 JD01 JN12 JQ22 JQ81 JT02 JT05 JT06 JT33

Claims (2)

[Claims] 1. An injection device (1) having first driving means for driving a screw in a rotational direction and an axial direction, and a movable mold (K2) in a mold clamping direction with respect to a fixed mold (K1). An injection molding machine comprising: a mold clamping device (20) having a second driving means for driving in a mold opening direction; wherein the first driving means comprises an electric rotary motor (5, 9);
An injection molding machine characterized in that the second driving means comprises a hydraulic piston / cylinder unit (40). 2. An injection device (1) having first driving means for driving a screw in a rotational direction and an axial direction, and a movable mold (K2) in a mold clamping direction with respect to a fixed mold (K1). An injection molding machine comprising a mold clamping device (20) provided with a second driving means for driving in the mold opening direction, wherein the first driving means and the injection device (1) are arranged in the axial direction. The driving means for moving is an electric rotary motor (5, 9, 12)
And the second drive means and the ejector device drive means are provided with hydraulic piston / cylinder units (40, 4,
5) An injection molding machine comprising: