JPH0686083B2 - 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 an injection molding machine which heats and fluidizes a required resin material and pushes it into a mold to mold a plastic product.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional electric injection molding machine having a mold clamping device A and an injection device B. The mold clamping device A is erected on a pedestal 3 in a state where a fixed platen 1 and an end plate 2 face each other, and a movable platen 5 is mounted on a tie bar 4 horizontally laid between the fixed platen 1 and the end plate 2. Is supported so that it can reciprocate. A fixed mold 1a and a movable mold 5a are fixedly provided on the surfaces of the fixed platen 1 and the movable platen 5 facing each other, and a mold M is constituted by them. A toggle mechanism 6 is arranged between the end plate 2 and the movable platen 5, and the toggle mechanism 6 is connected to a ball screw mechanism 7 arranged on the end plate 2.
The ball screw mechanism 7 is driven by a mold clamping motor 11 via a timing pulley 8, a timing belt 9, and a timing pulley 10 to move the movable platen 5 to perform mold clamping and mold opening. ing. The toggle mechanism 6 is configured to connect a plurality of link members 12 to increase the mold clamping pressure according to the lever principle.
Further, the ball screw mechanism 7 includes a ball nut 14 rotatably supported by the end plate 2 via a thrust bearing 13 and a ball screw 15 in combination.
The ball screw 15 is linearly moved by rotating.

On the other hand, in the injection device B, a slide tie bar 18 is horizontally installed between a pair of support plates 16 and 17 which are erected on the pedestal 3a so as to face each other.
A drive board 19 is reciprocally supported at 8. in front
An injection cylinder 21 equipped with a nozzle 20 and a heating device (not shown) is fixedly supported on a support board 16 (on the side of the mold clamping device A), and a screw 22 is axially movable in the injection cylinder 21. Is inserted into the base end 2 of the screw 22.
2a is rotatably supported by the drive board 19 via a thrust bearing 23. This screw 22 is the drive board 1
A ball screw mechanism provided between the drive plate 19 and the rear support plate 17 while being rotated by a screw rotation motor 24 mounted on the drive shaft 9 via a timing pulley 25, a timing belt 26, and a timing pulley 27. 28
Is driven by the injection motor 32 via the timing pulley 29, the timing belt 30, and the timing pulley 31 to reciprocate the drive board 19 itself, and the screw 2
2 is configured to move forward and backward in the axial direction within the injection cylinder 21. In addition, a device for moving one of the pedestals 3 and 3a to move the nozzle 20 forward and backward, an ejector device (not shown) provided in the mold M for ejecting and dropping the molded product, and the like are provided. However, these devices are usually driven by converting the rotation of the electric motor into a linear motion by the ball screw mechanism.

In such an injection molding machine,
A series of operations, that is, opening / closing operation of the mold M, that is, moving operation of the movable platen 5, mold clamping operation, forward movement of the nozzle 20 as preliminary injection operation, injection operation of resin material into the mold M, A resin material supplying operation as preparation for injection, that is, a moving operation of the screw 22, an internal pressure removing operation of the resin material in the injection cylinder 21 for preventing defective molding, a nozzle 20 retracting operation,
A series of operations such as cooling / clamping continuation (holding pressure) operation to ensure a predetermined molding quality in the mold M, opening / closing motion of the mold M, ejector advancing operation for ejecting the molded product, ejector retracting operation, etc. The operation is performed continuously.

[0005]

By the way, such an electric injection molding machine is provided with an ejector device for taking out a molded product from a mold. This ejector device has a transmission mechanism. Since the ejector device is composed of the mechanical parts including the structure, the structure of the ejector device is complicated, the manufacturing cost is high, and the maintenance is not easy. In addition, there is a drawback that an operation delay is inevitable due to play or friction between the ball screw and the ball nut, a vibration moment of the ball screw, or the like, and a highly accurate driving operation cannot be obtained.

The present invention has been made in view of the above circumstances, and the ejector device has a simple structure, a low manufacturing cost, easy maintenance, high operation accuracy, and a protruding position can be set in a mold. It is an object of the present invention to provide an injection molding machine having various features such that it can be easily changed according to the form of the above.

[0007]

In order to solve the above problems, the present invention employs the following injection molding machine. That is, a mold clamping device that moves a movable platen forward and backward with respect to a fixed platen to open and close a mold attached to them, and an ejector device that is provided in one of the molds and takes out a molded product from the mold. And an injection device that supplies a resin to the mold by driving a screw inserted rotatably into and out of an injection cylinder provided on one side of the mold clamping device. The ejector device includes an ejector pin that is inserted into the mold and can move back and forth, an ejector plate that holds the ejector pin, and a metal guide pin that penetrates and guides the ejector plate, and a drive mechanism of the ejector device. Is a linear motor including the guide pin serving as a secondary conductor and a stator provided on the ejector plate. That.

[0008]

In the injection molding machine of the present invention, the drive mechanism of the ejector device is a linear motor provided with the guide pin serving as a secondary conductor and the stator provided on the ejector plate.
Since a motion mechanism composed of a ball screw and a ball nut and other transmission mechanism are unnecessary, the structure is simple, the manufacturing cost is low, the maintenance is easy, and high motion accuracy is obtained. Further, the setting of the protruding position can be easily changed according to the shape of the mold, so that the operation efficiency is high.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An injection molding machine according to the present invention will be described below with reference to FIGS. In the figure, the same parts as those of the conventional injection molding machine are designated by the same reference numerals and the description thereof will be omitted. Figure 1
1 shows an injection molding machine according to an embodiment of the present invention. In the mold clamping device A, a metal rod (secondary conductor)
A mold clamping linear motor 43 is constituted by 41 and a cylindrical stator 42 fixedly mounted on the crosshead 6a of the toggle mechanism 6. On the other hand, in the injection device B, the upper slide tie bar 18 serves as the secondary conductor 44, and the tubular stator 4 is provided at a position where the drive board 19 is fitted onto the secondary conductor 44.
5 is fixed, and the injection linear motor 46 is constituted by both of them. Above linear motors 43, 4
As 6, a linear induction motor, a linear direct current motor, or the like that makes the best use of the characteristics of each is adopted.

A position detector for detecting the position of the movable platen 5 or the drive plate 19 and a pressure detector for directly or indirectly detecting the pressure of the resin in the mold M are attached. The difference between the detection value of the detector and the preset position and pressure setting value is detected, and the linear motors 43 and 46 control mechanism (consisting of the direction / speed command section, torque limiter, etc.) And a control device for generating a control signal. As an example of the above pressure detector, a load cell is attached to the base end portion 22a of the screw 22 to detect the strain of the base end portion, and the screw 2
An example is one in which the reaction force applied to 2 is detected.

FIG. 2 shows the ejector device C of the mold clamping device A.
It is a figure which shows the part of the linear motor of the drive mechanism of FIG. A through hole 52 provided in the ejector plate 51 is inserted into the rear surface of the movable platen 5 to remove the ejector plate 51.
A guide pin 53 that slidably supports the movable plate 5 is provided so as to project, and the movable platen 5 (and a movable mold (not shown)) is inserted into the surface of the ejector plate 51 that faces the movable platen 5. The ejector pin 54 that is in contact with the cavity of the mold M is fixed. A cylindrical stator 55 is provided inside the through hole 52 of the ejector plate 51.
Is fixed to form an ejector linear motor 56 using the guide pin 53 as a secondary conductor. As this linear motor, a linear DC motor or the like, which is easy and accurate in position control, is suitable.

Next, the operation of the injection molding machine configured as described above will be described. First, prior to the operation of the injection molding machine, various speed, position, and pressure set values are input to the control device. Next, the injection molding process is continuously performed, and the one cycle process will be described. At the mold closing start time of one injection molding process, the control device generates a drive signal for the mold clamping linear motor 43 to reduce the speed and pressure of the mold protection section (region) to protect the mold M. The speed and the torque limiter are controlled so that the movable die 5a is moved to close the die. Next, a torque limiter signal corresponding to the mold clamping force is sent to the control device to clamp and hold the movable mold 5a and the fixed mold 1a at a constant pressure, and the injection linear motor 46 is driven to move the injection mold 21 inside the injection cylinder 21. The resin material is injected into the mold M.

Thereafter, the difference between the measured value of the pressure detector provided at the base end portion 22a of the screw 22 and the pressure set value input in advance to the control device is detected, and the linear injection injection is performed in accordance with the detected value. A signal for driving the motor 46 to control the holding pressure is generated. In this case, a method in which a speed command value is constant and a control signal is sent to a torque limiter to specify and control the torque, and a method in which the torque is constant and a speed command value is specified and controlled can be considered. Next, the screw rotation motor 24 is driven to supply the next material into the injection cylinder 21. At this time, by a control method similar to that at the time of holding pressure, when the scheduled solidification is completed, the mold clamping linear motor 43 is rotated in reverse to perform mold opening. At the set operating position of the ejector 54, the ejector linear motor 56 is driven, and the molded body on which the ejector 54 is molded is pushed out from the mold, and the one cycle process is completed.

As is apparent from the above description of the structure and operation, in such an injection molding machine, since the drive source is the linear motors 43, 46, 56, a transmission mechanism such as a timing pulley or a timing belt. , And a mechanism for converting rotary motion to linear motion are unnecessary, and the delay in operation is reduced in control. Therefore, it is possible to control the pressure in the mold M at the time of cooling, which has a great influence on the quality of the molded product, with high accuracy, promote the smooth progress of the process, and improve the molding efficiency. Further, since the ejector device C does not have a motion mechanism composed of a ball screw and a ball nut or other transmission mechanism, the structure is simplified,
The manufacturing cost is low, maintenance is easy, and high motion accuracy is obtained. Further, since the setting of the protruding position can be easily changed according to the shape of the mold, there is an effect that the operation efficiency is high.

In the above description, a so-called closed control is provided in which a pressure detector for detecting the holding pressure is provided at the screw base end portion 22a, and the detected value is fed back to the control device to control the injection linear motor 46. However, the voltage to the torque limiter of the control mechanism of the injection linear motor 46 at each stage is not provided in advance, and the pressure detector is not provided.
An open control method may be used in which the current value is appropriately determined and the control is performed only according to the value.

[0016]

As described above, according to the injection molding machine of the present invention, the mold clamping device for moving the movable platen forward and backward relative to the fixed platen to open and close the molds attached thereto, and the metal mold. An ejector device provided on one of the molds to take out a molded product from the mold, and a screw rotatably inserted into and retracted from the injection cylinder provided on one side of the mold clamping device are driven. In an injection molding machine including an injection device that supplies resin to a mold, the ejector device includes an ejector pin that is inserted into the mold and is capable of advancing and retracting, an ejector plate that holds the ejector pin, and the ejector plate. The ejector device driving mechanism includes a metal guide pin that penetrates and guides the guide pin that serves as a secondary conductor, and the ejector plate. Since it was decided comprising a linear motor that includes a stator, the structure of the ejector apparatus can be simplified, together with the low manufacturing cost and easy maintenance. Also, because it is driven without a transmission mechanism,
In addition to high movement accuracy, the setting of the protruding position can be easily changed according to the shape of the mold, so that it has excellent effects such as high operation efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an injection molding machine that is an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a drive mechanism of an ejector device of an injection molding machine which is an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional injection molding machine.

[Explanation of symbols]

 1a Fixed type 5a Moving type 21 Injection cylinder 22 Screw 43 Linear motor for mold clamping 46 Linear motor for injection 51 Ejector plate 52 Through hole 53 Guide pin 54 Ejector pin 55 Stator 56 Linear motor for ejector M Mold

Claims (1)

[Claims] 1. A mold clamping device for moving a movable platen forward and backward with respect to a fixed platen to open and close a mold attached to the movable platen, and for removing a molded product provided in one of the molds from the mold. Injection molding machine including an ejector device and an injection device that drives a screw that is inserted into the injection cylinder provided on one side of the mold clamping device and rotatably inserted to supply resin to the mold. In the ejector device, the ejector device includes an ejector pin that is inserted into the mold and can move back and forth, an ejector plate that holds the ejector pin, and a metal guide pin that penetrates and guides the ejector plate. Is characterized in that it is composed of a linear motor including the guide pin serving as a secondary conductor and a stator provided on the ejector plate. Injection molding machine according to.