JP3732467B2 - Injection molding machine - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an injection molding machine in which two mold mounting boards are arranged so as to be close to and away from each other, the mold mounting board is driven by rotation of a screw shaft driven by a motor, and mold clamping and mold opening are performed.
[0002]
[Prior art and problems to be solved by the invention]
Clamping of a conventional injection molding machine is performed by attaching one mold of a pair of molds to a fixed platen, attaching the other mold to a movable platen, and pressing the movable platen to the fixed platen side with a hydraulic cylinder or toggle mechanism. Is going.
However, the acquisition of 1SO14001, which is said to satisfy a certain level in the factory environment, is difficult to obtain when working oil such as a hydraulic device is used.
In addition, some mold clamping devices using a toggle mechanism use a motor as a drive source. However, the toggle mechanism has a problem in that the length in the mold clamping and mold opening directions increases due to the structure of the link. In particular, in a vertical injection molding machine in which a mold moves up and down to perform clamping and opening, the height of the molding machine becomes too large, so that it is hardly performed.
[0003]
In view of this, the applicant has devised a mold clamping device that clamps and opens the mold by passing a motor-driven screw shaft through the movable board and slidingly driving the movable board with screw thrust.
However, if an appropriate clamping pressure is to be maintained during mold clamping, the screw shaft must be greatly decelerated and the screw shaft must be rotated, the mold clamping and mold opening speeds are reduced, and the molding efficiency is reduced.
In addition, if the molten resin is excessively injected into the mold cavity during mold clamping, a force that forcibly opens the mold is generated, and a twisting force acts on the screw shaft that drives the movable platen. Even if the motor was rotated in reverse for opening, the screw shaft did not rotate. In this case, while applying a rotational force to the screw shaft and hitting the movable plate with a hammer or the like to give an impact, the screw shaft could be rotated. Also, it is impossible to maintain the accuracy of the machine.
[0004]
The present invention makes it possible to solve the above-mentioned problems by making two mold mounting plates face each other so as to be close to each other and driving both mold mounting plates with screw thrust generated by a reduced speed rotation of a screw shaft using a servo motor as a drive source. It will clarify the molding machine.
[0005]
[Means for solving the problems]
In the injection molding apparatus of the present invention, on the frame (1), the first mold mounting plate (2) and the second mold mounting plate (4) are arranged facing each other so as to be close to each other, and both mold mounting plates (2) ( 4) is linked to driving means for sliding driving with screw thrust using servo motors 3 and 5 as driving sources, respectively, and the driving means on the first type mounting plate 2 side is a first reduction gear (large reduction gear). 31), the driving means of the second type mounting plate (4) includes a second reduction gear (51) of small reduction, and both servo motors (3) and (5) are connected to the control unit (7) One of the molds (81) of the injection mold (8) is attached to the first mold mounting plate (2), and the other mold (82) is mounted to the second mold mounting plate (4).
[0006]
[Action and effect]
When clamping the mold, the second servo motor (5) is rotated, and the second mold mounting board (4) is slid by the screw thrust generated by the rotation of the motor, so that the mold (82) on the board is opposed to the other party. The mold (81) on the first mold mounting plate (2) is moved close to the second mold mounting plate (4) at the mold clamping position.
The first servo motor (3) is rotated, and the first mold mounting plate (2) is slid toward the second mold mounting plate (4) by the screw thrust generated by the rotation of the motor, so that the first mold mounting plate (2) The upper die (81) is pressed against the counterpart die (82).
The first servo motor (3) is controlled to maintain a preset clamping pressure.
[0007]
The slide stroke of the second type mounting plate (4) is larger than the sliding stroke of the first type mounting plate (2), but the second type mounting plate (4) is the second reduction gear (51) with a small reduction ratio. Therefore, the time required to slide from the mold opening position to the mold clamping position can be shortened because the slide driving is performed by the screw thrust of the screw shaft (41) that is driven to rotate at a relatively high speed.
On the other hand, the first type mounting board (2) is slid by the screw thrust of the screw shaft (21) driven to rotate at a low speed via the first reduction gear (31) having a large reduction ratio. Although the speed is slow, since the slide stroke is short, the time required to move from the mold opening position to the mold clamping position is short.
[0008]
The timing of sliding movement of the second mold mounting board (4) and the first mold mounting board (2) is as follows. After the second mold mounting board (4) is slid to the mold clamping position, the first mold mounting is performed. It is not necessary to restrict the board (2) to the second mold mounting board (4) side, but the mold (82) on the second mold mounting board (4) located at a preset clamping position. On the other hand, if the mold (81) on the first mold mounting plate (2) can be pressed, the timing of the sliding movement of the first and second mold mounting plates (2) and (4) can be freely set. The time required for mold clamping can be shortened as much as possible.
[0009]
First, the first mold mounting plate (2) is slid to the mold clamping position to stand by, and then the second mold mounting plate (4) is slid to the first mold mounting plate (2) side to mold ( 81) (82) is closed, and when the mold (81) (82) is closed, the slide movement of the second mold mounting plate (4) is stopped and held in a fixed state, and the first mold mounting plate (2) The mold clamping pressure can also be obtained by pressing the first mold mounting plate (2) toward the second mold mounting plate (4) with the force of the first servo motor (3) on the side.
[0010]
In mold opening, the first mold mounting plate (2) and the second mold mounting plate (4) are slid in the opposite direction to the mold clamping.
[0011]
When molten resin is excessively injected into the mold cavity at the time of molding, the mold (8) tries to open and the screw shafts (21) of the first mold mounting plate (2) and the second mold mounting plate (4) ( 41) becomes unreasonable, the screw shafts (21) and (41) are bent, and the load when the screw shafts (21) and (41) are reversely rotated for mold opening increases. However, in the present invention, the first mold mounting plate (2) is driven by the screw thrust of the screw shaft (21) that is rotationally driven via the first reduction gear (31) of large deceleration. ) Is increased in accordance with the amount of deceleration, and the screw shaft (21) can be smoothly rotated. Therefore, it is Rukoto smoothly slide moved away first type mounting plate (2) from the second mold mounting platens (4). If the mold (81) on the first mold mounting board (2) is separated from the mating mold (82), the pressure on the second mold mounting board (4) is released, so the second mold mounting board (4) side The twisting of the screw shaft (21) is also eliminated, and the slide return to the original position of the second mold mounting plate (4) is also performed smoothly.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The drawing shows an example in which the present invention is applied to a vertical injection molding.
The frame (1) of the injection molding machine has vertical plates (11) and (11) parallel to the left and right, and has a horizontal table (13) at the lower part between the vertical plates (11) and (11). (13) The first type mounting plate (2) can be moved up and down with a small stroke on the top, and the second type mounting plate (4) can be moved up and down with a large stroke above the first type mounting plate (2). Has been deployed.
[0013]
A plurality of guide shafts (22) and (22) project from the lower surface of the first type mounting plate (2), and the guide shafts (22) are mounted on the guide tubes (14) and (14) provided on the horizontal table (13). (22) is slidably penetrated.
A screw shaft (21) is projected from the center of the lower surface of the first mold mounting plate (2), and a nut (23) is screwed onto the screw shaft (21).
Nut (23) is rotatably supported lifting in a fixed position in the housing (24) of the first speed reducer (31).
[0014]
The first servo motor (3) for rotationally driving the nut (23) is connected to the nut (23) via the first reduction gear (31) for large reduction, and the first mold mounting plate (2) is connected to the nut (23). A driving means for moving up and down is configured.
The first speed reducer (31) of the embodiment is a worm speed reducer, and the gear meshed with the worm is meshed with the outer peripheral tooth surface of the nut (23).
Due to the rotation of the first servo motor (3), the nut (23) rotates at a low speed by being decelerated by the first speed reducer (31), and the first die mounting plate (2) is raised or lowered by the screw thrust.
The mold clamping and mold opening of the injection molding machine of the present invention almost depend on the lifting stroke S2 of the second mold mounting plate (4) described later, and the lifting stroke S1 of the first mold mounting plate (2) is a slight amount. For example, it can be 1 mm or less.
[0015]
The 2nd type mounting board (4) is protrudingly provided by the screw shaft (41) (41) on both ends.
Guide cylinders (12) and (12) project from the front upper ends of both vertical plates (11) and (11) of the frame (1), and screw shafts (41) ( 41) is passed through in a rotatable manner.
A nut (42) is screwed onto each screw shaft (41), and the nut (42) is rotatably supported at an upper fixed position of the guide tube (12).
A second servo motor (5) is connected to the nut (42) via a second speed reducer (51) with a small reduction ratio provided at the upper part of the guide cylinders (12) and (12), and the second mold mounting plate is attached. The drive means which raises / lowers (4) is comprised.
The nut (42) is rotated by the rotation of the second servo motor (5), and the screw shaft (41) is moved up and down by the screw thrust.
In the embodiment, two second reducers (51) (51) and second servo motors (5) (5) are connected to two nuts (42) and (42), respectively, and the two servo motors are (5 ) (5) is controlled to operate synchronously.
[0016]
One mold (81) of a pair of injection molds (8) is mounted on the upper surface (20) of the first mold mounting plate (2), and the lower surface (40) of the second mold mounting plate (4) is mounted on the lower surface (40). The other mold (82) is attached to face the counterpart mold (81).
The lifting stroke S2 of the second mold mounting plate (4) is set to an amount that the mold (8) opens to such an extent that the molded product can be taken out from the mold (8) only by lifting and lowering the second mold mounting plate (4).
[0017]
Two guide shafts (44) and (44) are projected upward on the second type mounting plate (4), and the injection unit (6) is slidably arranged on the guide shafts (44) and (44). Is done.
The injection unit (6) is configured by mounting an injection cylinder (64) on a slide base (60) slidably disposed on guide shafts (44) (44).
The slide table (60) is formed by connecting an upper plate (61) and a lower plate (62) fitted to the guide shafts (44) and (44) by a plurality of connecting shafts (63).
The slide table (60) is connected to a lifting / lowering device (not shown) dedicated to nozzle touch, which is provided on the second type mounting board (4).
[0018]
The injection cylinder (64) includes a hopper (65) for charging resin pellets, and a nozzle (68) at the tip is inserted into a hole (43) provided in the second mold mounting plate (4).
On the slide table (60), an injection servo motor (67) for rotating an injection screw (not shown) in the injection cylinder (64) is mounted via a bracket (66).
[0019]
The injection servo motor (67), the first mold mounting plate (2), the first mold mounting plate (4), the first and second servo motors (3) and (5) for slide driving, and nozzle touch dedicated The lifting device (not shown) is connected to and controlled by the control unit (7).
The control unit (7) includes input means (not shown), the mold clamping height position where the molds (81) and (82) are in contact with each other, the rotational speed of the servo motors (3), (5) and (67), The lifting stroke of the first type mounting board (2) and the second type mounting board (4) can be set.
[0020]
In the embodiment, the screw shaft (21) and nut (23) on the first mold mounting plate (2) side and the screw shaft (41) and nut (42) on the second mold mounting plate (4) side are both A ball screw shaft and a ball nut, the rotational friction of the screw shafts (21) and (41) is small, and there is no backlash of screw engagement.
[0021]
However, when the injection molding machine is operated, the mold clamping height position where the molds (81) and (82) are in contact with each other is set from the height of the molds (81) and (82), the height of the molded product, and the like. The lifting stroke of the mold mounting plate (4) is optimally set in consideration of the height of the molded product.
[0022]
At the time of mold clamping, the second servo motor (5) is driven to rotate the screw shaft (41), and the second mold mounting plate (4) is lowered to the mold clamping position by screw thrust.
Next, the first servo motor (3) is driven to slide the first mold mounting board (2) toward the second mold mounting board (4), and the mold (81) on the first mold mounting board (2) is moved. Is pressed against the other mold (82).
The first servo motor (3) is controlled to maintain a preset clamping pressure.
[0023]
The slide stroke S2 of the second type mounting plate (4) is much larger than the slide stroke S1 of the first type mounting plate (2), but the second type mounting plate (4) has a second reduction ratio of the second. Since it is slid by the screw thrust of the screw shaft (41) that rotates at high speed via the speed reducer (51), the time required from the mold opening position to the mold clamping position can be shortened.
On the other hand, the first-type mounting board (2) is slid by the screw thrust of the screw shaft (21) rotating at a low speed via the first reduction gear (31) having a large reduction ratio, so that the sliding speed is low. However, since the slide stroke S1 is much shorter than the slide stroke S2 of the second mold mounting plate (4), the time required to move from the mold opening position to the mold clamping position can be shortened.
[0024]
In mold opening, the first mold mounting plate (2) and the second mold mounting plate (4) are slid in the opposite direction to the mold clamping. As with mold clamping, the mold can be opened in a short time.
[0025]
If excessive molten resin is injected from the injection cylinder (64) into the mold cavity during molding, the mold (8) will open and the first mold mounting plate (2) and the second mold mounting plate (4) will open. The screw shafts (21) and (41) are forcibly applied and the screw shafts (21) and (41) are bent. In this way, even if the screw shafts (21) and (41) are rolled and it is difficult to open the mold, the first mold mounting plate (2) is connected to the screw shaft via the first reduction gear (31) for large reduction. Since (21) is driven, the rotation of the screw shaft (21) is smooth, and the first mold mounting plate (2) slides smoothly in the direction away from the second mold mounting plate (4). (81) is separated from the counterpart mold (82). As a result, the pressure on the second mold mounting plate (4) is released, and the twisting of the screw shaft (21) on the second mold mounting plate (4) side is eliminated, and the original position of the second mold mounting plate (4) is eliminated. The slide is smoothly returned to the front.
[0026]
The servo motors (3) and (5) for driving the screw shafts (21) and (41) have characteristics that can be controlled with high accuracy, as is well known. Therefore, as described above, it is necessary to limit the first mold mounting board (2) to the second mold mounting board (4) side after the second mold mounting board (4) is lowered to the mold clamping position. No, the die (81) on the first die mounting plate (2) is pressed against the die (82) on the second die mounting plate (4) located at a preset die clamping position. The timing of sliding movement of the first and second mold mounting plates (2) and (4) can be set freely and the time required for mold clamping can be shortened as much as possible.
[0027]
In the embodiment, between the first type mounting plate (2) and the second type mounting plate (4), three sides of the front side and the left and right sides are opened except for the rear side which is obstructed by the frame (1). Therefore, workability, such as taking out a molded product and exchanging molds, is improved.
[0028]
In the embodiment, since the second speed reducer (51) on the second mold mounting plate (4) side is a worm reducer, the first mold mounting is started from the time when the second mold mounting plate (4) is lowered to the mold clamping position. There is no possibility that the second reduction gear (51) rotates in the reverse direction even when a force for pushing up the second type mounting plate (4) is applied by raising the plate (2). Therefore, when the second mold mounting plate (4) is lowered to the mold clamping position, the power supply to the second servo motor (5) can be cut off.
However, since the servo motor can apply the brake to the rotation by applying the brake pulse, the second reduction gear (51) is not necessarily limited to the worm reduction gear.
[0029]
In the embodiment, the first speed reducer (31) on the first type mounting plate (2) side is also a worm speed reducer. However, if the speed reducer is capable of large speed reduction and fits in a small size, it is not necessary to limit it to the worm speed reducer. Absent.
[0030]
The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.
[0031]
For example, in the embodiment, the screw thrust was obtained by rotating the nut, but the screw shaft was screwed into the first mold mounting plate (2) and the second mold mounting plate (4), and the screw shaft was rotated. It is also possible to obtain a screw thrust and slide the first mold mounting plate (2) and the second mold mounting plate (4) in the mold clamping direction or the mold opening direction.
[0032]
A reduction gear with a large reduction ratio is connected to the second type mounting plate (4) side, and a reduction gear with a small reduction ratio is connected to the first type mounting plate (2) side, so that the first type mounting plate (2 The same effect as described above can be obtained even if the slide stroke of the second type mounting plate (4) is reduced.
[0033]
The injection molding machine of the present invention can also be implemented in horizontal injection molding in which the mold is opened in the horizontal direction and clamped.
[0034]
Further, in the embodiment, the first servo motor (3) and the first speed reducer (31) on the first type mounting plate (2) side are each one, and the screw shaft (21) of the first speed reducer (31) is used. Although it is located in the center of the lower surface of the first mold mounting plate (2), it may interfere with the mounting of a device (not shown) for projecting a product from the mold (81). In this case, screw shafts are provided on both the left and right sides of the first type mounting plate (2), and the first reduction gear and the first servo motor are connected to each screw shaft, and the center of the lower surface of the first type mounting plate (2). The problem can be solved by opening.
[Brief description of the drawings]
FIG. 1 is a front view of an injection molding machine.
FIG. 2 is a side view showing a part of the injection molding apparatus in cross section.
FIG. 3 is a front view of the injection molding machine in a mold open state.
[Explanation of symbols]
(1) Frame
(2) Type 1 mounting board
(21) Screw shaft
(3) 1st servo motor
(31) First reduction gear
(4) Type 2 mounting board
(5) Second servo motor
(51) Second reducer

Claims (1)

On the frame (1), the first type mounting plate (2) and the second type mounting plate (4) are arranged opposite to each other so as to be able to approach and separate from each other, and servo motors (3 ) (5) is used as a drive source, and driving means for sliding driving with screw thrust is linked. The driving means on the first mold mounting plate (2) side includes the first reduction gear (31) for large deceleration, and the second mold mounting The drive means of the panel (4) includes a second reduction gear (51) with a small speed reduction, and both servo motors (3) and (5) are connected to the control section (7) to form a pair of injection molds (8). One mold (81) is attached to the first mold mounting board (2) and the other mold (82) is attached to the second mold mounting board (4).
Three sides except for the frame ( 1 ) are open between the first type mounting plate ( 2 ) and the second type mounting plate ( 4 ), and the first type mounting plate ( 2 ) and the second type mounting plate ( 4) ) Slides up and down to perform mold clamping and mold opening. During mold opening and clamping, the slide stroke of the second mold mounting board (4) is slid to the first mold mounting board (2). An injection molding machine characterized in that the clamping pressure is maintained by controlling both servo motors (3) and (4) during mold clamping, which is larger than the stroke.

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