JP2005238570A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always keep mold touch force to a good predetermined value without causing irregularity in an injection molding machine constituted so as to apply compression force to a resin by a core mold. <P>SOLUTION: The injection molding machine, in which compression force is applied to the resin injected/charged in a mold by the core mold capable of moving forward and rearward with respect to a movable mold and forming one side of a cavity, comprises a moving plate integrated with the core mold to advance and retreat, a first servomotor for use in the opening and closing/compressing of the mold for driving a toggle link mechanism for allowing the moving plate to advance and retreat, a movable mold holding plate loaded with the movable mold and mounted on the moving plate to advance and retreat with respect to the moving plate and a second servomotor for keeping mold touch force having a capacity smaller than that of the first servomotor and mounted on the moving plate to allow the movable mold holding plate to advance and retreat. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, a core mold that can move back and forth with respect to the movable mold and that forms one surface of a cavity is disposed in the movable mold, and the core mold is used to inject the mold into the mold. The present invention relates to an injection molding machine configured to apply a compressive force to a filled resin.

Die touch for maintaining the state that the PL (Parting Line) surface of the movable side mold with a built-in core mold and the fixed side mold are in close contact in an injection molding machine for compression molding using a core mold Technology that obtains force by spring force, and obtains large pressing force to apply compressive force to the resin through the core mold with the driving force of the servo motor for mold opening and closing (for mold clamping) Is known (see Patent Document 1). In the injection molding machine for compression molding described in Patent Document 1, when the core mold is configured to form one surface of the cavity, the pressure of the resin injected and filled in the mold is applied to the core mold. Therefore, taking into consideration that it does not apply to the movable mold, the mold touch force at the time of mold touch is borne by the force of the spring, and the large pressing force to apply compressive force to the resin is for mold opening and closing By using the driving force of the servo motor, the number of driving sources for maintaining the mold touch force is reduced.
JP 2000-31005 A

  However, in the technique described in Patent Document 1, since a force for maintaining the mold touch is applied to the spring, variations in the mold touch force are likely to occur due to variations in the spring force of the spring. The technique described in Patent Document 1 has a configuration that requires an eject mechanism including an eject pin and its drive source, although the drive source for maintaining the mold touch force is reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a core mold that can move back and forth with respect to the movable mold and that forms one surface of the cavity in the movable mold. In an injection molding machine that is arranged to apply a compressive force to the resin injected and filled in the mold by this core mold, the mold touch force can always be maintained at a good predetermined value without variation. Is to make it. Another object of the present invention is to realize a molding resin mold release mechanism that does not require a dedicated eject pin for molding resin mold release or a drive source dedicated to ejection.

In order to achieve the above-described object, the present invention provides a core mold in which a core mold that can be moved back and forth with respect to the movable mold and that forms one surface of a cavity is disposed in the movable mold. In the injection molding machine that applies compressive force to the resin injected and filled in the mold by
A movable plate that moves forward and backward integrally with the core mold, a first servomotor for opening / closing and compressing the mold that drives a toggle link mechanism that moves the movable plate forward and backward, and a movable mold are mounted and moved. From a movable mold holding plate mounted on the plate and movable back and forth with respect to the moving plate, and a first servo motor mounted on the moving plate and capable of moving the movable mold holding plate back and forth And a second servo motor for maintaining a small-capacity mold touch force,
With the mold touch force at the time of mold touch maintained by the second servo motor, resin is injected and filled in the mold, and the toggle link mechanism is extended by the driving force of the first servo motor. In addition, a compressive force is applied to the resin in the mold through the core mold.
In addition, a rotating part of a ball screw mechanism that is rotationally driven by the second servomotor is rotatably held on the moving plate, and a linearly moving part of the ball screw mechanism that is screwed to the rotating part is connected to the movable side. The mold holding plate is connected so as to move together, and the second servo motor is configured to be pressure feedback controlled so as to maintain a predetermined touch force when the mold is touched.
Further, a part of the molding resin can be obtained by driving the second servo motor so as to move the movable mold relative to the core mold during the mold opening or after the mold opening is completed. It is configured to perform mold release.

  According to the present invention, the mold is controlled by pressure feedback control of the second servomotor for maintaining the mold touch force having a smaller capacity than the first servomotor for opening / closing and compressing the mold that drives the toggle link mechanism. Since the mold touch force at the time of touch is maintained, the mold touch force can always be maintained at a good predetermined value without variation. In addition, the mold is released by releasing a part of the molding resin by moving the movable mold relative to the core mold by the second servo motor during the mold opening or after the mold opening is completed. Therefore, it is not necessary to use a dedicated eject pin or a dedicated drive source for ejecting, so that the number of drive sources can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 3 are diagrams showing a configuration of a mold opening / closing system mechanism of a vertical injection molding machine according to an embodiment of the present invention (hereinafter referred to as the present embodiment), and FIG. 2 shows a state in which the molten resin is injected and filled into the mold, FIG. 2 shows a compression state in which a compressive force is applied to the resin in the mold by the core mold, and FIG. 3 shows a mold open state. Is shown. Note that forward in the specification of the present application refers to linear movement in a direction approaching the fixed mold, and backward refers to linear movement in a direction away from the fixed mold.

  1 to 3, 1 is a tail stock, 2 is a moving plate, 3 is a fixed die plate, and is omitted in FIGS. 1 to 3, but between the tail stock 1 and the fixed die plate 3. A plurality of tie bars are stretched over each end, and both ends of each tie bar are fixed to the tailstock 1 and the fixed die plate 3, respectively. The movable plate 2 is inserted and guided by each tie bar, and moves forward and backward. (Up and down movement) is possible.

  4 is a ball screw mechanism including a nut body 5 rotatably held by the tailstock 1 and a ball screw shaft 6 screwed into the nut body 5, and 7 is fixed to the nut body 5. In addition, a driven pulley 9 that is driven to rotate by a first servomotor 8 for mold opening / closing / compression (hereinafter referred to as a mold opening / closing servomotor 8) mounted on the tailstock 1 The toggle link mechanism 10 is provided so as to connect between the movable plate 2 and the movable plate 2 and is driven to extend / fold, thereby moving the movable plate 2 forward and backward. A toggle link 10 is fixed to the tip of the ball screw shaft 6. A crosshead which is an input end of the force of the mechanism 9, 11 is a load cell fixed to the upper surface of the moving plate 2, and 12 is a core mold holding plate fixed to the upper surface of the load cell 11. DOO, 13 is fixed to the core mold holding plate 12, the tip surface is a core metal mold for forming one surface of the cavity.

  Reference numeral 14 denotes a ball screw mechanism including a nut body 15 rotatably held by the moving plate 2 and a ball screw shaft 16 screwed to the nut body 15, and 17 denotes a nut body 15. A second servomotor 18 that is fixed and is mounted on the movable plate 2 for maintaining the mold touch force (hereinafter referred to as a touch servomotor 18; this touch servomotor 18 is a mold opening / closing servo. The driven pulley 19 is configured to be rotated by a servo motor having a small capacity compared to the motor 8, 19 is a connecting plate fixed to the end of the ball screw shaft 15, and 20 is a lower end of the connecting plate 19. The connecting shaft 21, which is fixed and inserted so as to be movable forward and backward with respect to the moving plate 2 and the load cell 11, is fixed to the upper end of the connecting shaft 20. Movable mold holding plates, 22 is a movable mold fixed to the upper surface of the movable mold holding plate 21.

  Reference numeral 23 denotes a fixed side mold fixed to the lower surface of the fixed die plate 3, and reference numeral 24 denotes a resin.

  1 to 3, the rotation of the mold opening / closing servomotor 8 is transmitted to the nut body 5 of the ball screw mechanism 4 via the driven pulley 7, and the rotation of the nut body 5 is caused by the linear motion of the ball screw shaft 6. It is converted and the direct power is transmitted to the cross head 10, and the cross head 10 moves forward or backward. When the crosshead 10 moves forward or backward, the toggle link mechanism 9 is driven to extend or fold, and the moving plate 2 moves forward or backward. As a result, the load cell 11 and the core mold are integrated with the moving plate 2. The holding plate 12 and the core mold 13 are moved forward or backward. Moreover, since each member 14-22 is also mounted on the movable plate 2, when the touch motor 18 holds the rotation position at a constant position, each member 14-22 is also The moving plate 2 is integrated with the moving plate 2 to move forward or backward.

  On the other hand, the rotation of the touch servomotor 18 is transmitted to the nut body 15 of the ball screw mechanism 14 via the driven pulley 17, and the rotation of the nut body 15 is converted into a linear motion of the ball screw shaft 16 so that the direct power is connected to the connecting plate 19. The connecting plate 19 moves forward or backward. When the connecting plate 19 advances or retracts, the connecting shaft 20, the movable mold holding plate 21, and the movable mold 22 are moved forward or backward together with the connecting plate 19.

  Next, the mold closing, compression, mold opening, and mold release operations of this embodiment will be described in order.

  Before the mold closing is started, the toggle link mechanism 9 is in a folded state, and the movable plate 2 is in a mold opening completion position. In this state, when the mold opening / closing servo motor 8 is rotated in a predetermined direction and the cross head 10 is advanced through the driven pulley 7 and the ball screw mechanism 4, the toggle link mechanism 9 is driven to extend and moves accordingly. The plate 2 moves forward. When the moving plate 2 moves forward, the load cell 11, the core mold holding plate 12, and the core mold 13 move forward, and the members 14 to 22 also move forward. Then, as the movable plate 2 moves forward, when the movable mold 22 touches the fixed mold 23 and reaches the state shown in FIG. 1, the mold opening / closing servomotor 8 temporarily changes its current rotational position. Is controlled to hold. In this state, as shown in FIG. 1, the toggle link mechanism 9 is not completely extended. On the other hand, the touch servomotor 18 mounted on the movable plate 2 is touched with a predetermined mold at least until the mold opening is started after the mold is touched based on a command from a system coat roller (not shown). Pressure feedback control is performed so as to maintain the force, and after touching the die, a constant die touch force is maintained by the touch servomotor 18. Note that the mold touch force by the touch servomotor 18 is sufficient with a small power that does not open the PL surface.

  As described above, a cavity formed by each mold closed by an injection system mechanism (not shown) in a state where the mold touch force is maintained by the touch servomotor 18 after touching the mold (for molding) The molten resin is injected and filled in the space. FIG. 1 shows a state immediately after the injection / filling.

  As soon as molten resin is injected and filled into the cavity, a mold opening / closing servo is performed based on a command from a system coat roller (not shown) in order to perform a compression operation to apply a compressive force to the resin in the mold. The motor 8 is driven in a direction in which the crosshead 10 is further moved forward, whereby the toggle link mechanism 9 is fully extended, and the state shown in FIG. 2 is reached. The rotation position is controlled to be maintained. When the toggle link mechanism 9 is fully extended, the force expansion rate of the toggle link mechanism 9 is maximized, and a large pressing force is applied to the core via the moving plate 2, the load cell 11, and the core mold holding plate 12. A large compressive force is imparted to the resin 24 in the mold as transmitted to the mold 13. At this time, the movable side mold 22 indirectly mounted on the movable plate 2 via the forward / backward moving mechanism is moved to the fixed side mold 23 by the slight advance of the movable plate 2 due to the toggle link mechanism 9 being fully extended. However, as described above, since the touch servomotor 18 is pressure feedback controlled so as to maintain a constant mold touch force, the movable mold 22 is used for touch. By rotating the servo motor 18, the servo plate 18 moves backward by a small amount with respect to the moving plate 2 to maintain a constant mold touch force. Therefore, the mold touch force is always kept at a good constant value. Further, the mold touch force only needs to be a small value that can maintain the mold touch. Therefore, even when a foreign object is sandwiched between the movable mold 22 and the fixed mold 23, Since an excessive mold touch force is not generated, there is no possibility of causing the mold damage.

  When the compression operation in the state shown in FIG. 2 is performed for a predetermined time and the resin in the mold is solidified and cooled, the mold is opened. The mold opening is performed from the state shown in FIG. 2 by rotating the mold opening / closing servo motor 8 in the direction opposite to the mold closing direction, and the mold opening / closing servo motor 8 crosses the driven pulley 7 and the ball screw mechanism 4. When the head 10 is retracted, the toggle link mechanism 9 is driven to be folded, and the moving plate 2 is retracted accordingly. When the moving plate 2 is retracted, the load cell 11, the core mold holding plate 12, and the core mold 13 are retracted, and the members 14 to 22 are also retracted. Then, when the moving plate 2 moves backward and the moving plate 2 reaches the mold opening completion position as shown in FIG. 3, the mold opening / closing servomotor 8 stops driving or maintains its current rotational position. To be controlled. On the other hand, the touch servo motor 18 mounted on the movable plate 2 determines the current rotational position from the pressure feedback control at a predetermined timing after the mold opening is started based on a command from a system coat roller (not shown). The control is temporarily switched to the holding control, and thereafter, the movable mold 22 is relatively positioned with respect to the core mold 13 at a predetermined timing during the mold opening operation or immediately after completion of the mold opening. It is controlled to move backward by a predetermined amount.

  As described above, when the movable mold 22 is retracted by a predetermined amount relative to the core mold 13, a molded product of the resin 24 attached to the core mold 13 and the movable mold 22 side by mold opening. Of the part 24 a and the sprue runner part 24 b, the sprue runner part 24 b is released from the movable mold 22. Accordingly, when the sprue and runner portion 24b is lifted by a molded product take-out machine (not shown), the molded product portion 24a attached to the core mold 13 is also easily released, and the solidified resin 24 is entirely removed from the mold. Will be removed. Therefore, as in the prior art, it is possible to release the molding resin without providing a dedicated eject pin for releasing the molding resin or a drive source dedicated to the ejection. Further, when the molded product portion 24a is a small optical component such as a lens, there is no possibility of damaging the molded product portion 24a with the eject pin.

  Here, in the above example, the movable mold 22 is moved backward relative to the core mold 13 in order to perform partial release of the resin (molding resin) 24. The mold 24a and the sprue / runner 24b of the resin 24 adhered to the core mold 13 and the movable mold 22 side by opening the mold so that the movable mold 22 is moved forward relative to the mold. Of these, the molded product portion 24 a may be released from the core mold 13.

  After the removal of the resin (molded resin) 24 is completed, the touch servomotor 18 is controlled so as to return the movable mold 22 to the reference position before the mold closing is started.

  In the above-described embodiment, application to a vertical injection molding machine is taken as an example, but it goes without saying that the present invention can also be applied to a horizontal injection molding machine.

It is explanatory drawing which shows the state which injected and filled the molten resin after the metal mold | die touch in the type | mold opening / closing system mechanism of the vertical type injection molding machine which concerns on one Embodiment of this invention. It is explanatory drawing which shows the state which has provided the compression force to resin in a metal mold | die by the core metal mold | die in the type | mold opening-closing system mechanism of the vertical injection molding machine which concerns on one Embodiment of this invention. It is explanatory drawing which shows the mold open state in the mold opening / closing system mechanism of the vertical injection molding machine which concerns on one Embodiment of this invention.

Explanation of symbols

1 Tail Stock 2 Moving Plate 3 Fixed Die Plate 4 Ball Screw Mechanism 5 Nut Body 6 Ball Screw Shaft 7 Driven Pulley 8 First Servo Motor for Mold Opening / Closing / Compression (Servo Motor for Mold Opening / Closing)
9 Toggle Link Mechanism 10 Crosshead 11 Load Cell 12 Core Mold Holding Plate 13 Core Mold 14 Ball Screw Mechanism 15 Nut Body 16 Ball Screw Shaft 17 Driven Pulley 18 Second Servo Motor for Maintaining Mold Touch Force (Servo Motor for Touch)
19 connecting plate 20 connecting shaft 21 movable side mold holding plate 22 movable side mold 23 fixed side mold 24 resin

Claims (3)

A resin that is injected into and filled in the mold by the core mold by disposing a core mold that can move back and forth with respect to the movable mold and that forms one surface of the cavity in the movable mold. In an injection molding machine that applies compressive force to
A moving plate that moves forward and backward integrally with the core mold;
A first servomotor for mold opening / closing and compression that drives a toggle link mechanism for moving the moving plate forward and backward;
The movable side mold holding plate mounted on the movable plate and capable of moving back and forth with respect to the movable plate, with the movable side mold mounted thereon,
A second servo motor mounted on the movable plate and capable of moving the movable mold holding plate back and forth, and maintaining a mold touch force having a smaller capacity than the first servo motor; Prepared,
In a state where the mold touch force at the time of mold touch is maintained by the second servo motor, resin is injected and filled in the mold, and the toggle link mechanism is not fully extended by the driving force of the first servo motor. An injection molding machine characterized in that a compressive force is applied to the resin in the mold through the core mold. The injection molding machine according to claim 1,
A rotating part of a ball screw mechanism that is rotationally driven by the second servo motor is rotatably held on the moving plate, and the movable side metal is attached to the linear moving part of the ball screw mechanism that is screwed to the rotating part. An injection molding machine characterized in that mold holding plates are connected so as to move together, and the second servomotor is pressure feedback controlled so as to maintain a predetermined touch force when the mold is touched. . In the injection molding machine according to claim 1 or 2,
In the course of mold opening or after mold opening is completed, the second servo motor is driven so as to move the movable mold relative to the core mold, thereby separating a part of the molding resin. An injection molding machine characterized by performing a mold.

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