JP2017128014A - Molding machine including toggle type clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive molding machine including a toggle type clamping device, having a large braking effect, applicable easily to an existing toggle type clamping device, and having a simple structure.SOLUTION: In an injection molding machine in which a ball screw (30) of a toggle mechanism (20) for mold opening/closing a mold is rotatively driven through a belt (36) wound between a small pulley (35) on the drive motor (34) side and a large pulley (33) on the ball screw (30) side, an electromagnetic brake (50) for braking the toggle mechanism is provided so that its brake pad (51) works on the rim side of the large pulley (33).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a molding machine such as an injection molding machine or a die-cast molding machine, and more specifically, a toggle type mold in which a toggle mechanism of a mold clamping device for opening and closing a mold is driven by a ball screw mechanism. The present invention relates to a molding machine provided with a fastening device.

  A molding machine, for example, an injection molding machine, generally includes an injection unit and a mold clamping unit, as is well known in the art. The injection unit includes a heating cylinder, a screw provided inside the heating cylinder so as to be driven in the rotational direction and the axial direction, and the like. On the other hand, the mold clamping unit is a fixed mold attached to the fixed platen, a movable mold attached to the movable platen, a mold clamping device for clamping the movable mold to the fixed die, etc. It is composed of A direct pressure type is also used as the mold clamping device, but a toggle type mold clamping device is often used. As is well known in the art, the toggle type mold clamping device includes a pair of long and short toggle links, a crosshead, and the like. Therefore, when the molten resin is injected from the injection unit into the mold clamped by the toggle type mold clamping device, the mold is opened after waiting for cooling and solidification, and a molded product is obtained.

  When molding as described above, if the motor driving the toggle mechanism stops, the toggle type clamping device is clamped by the elastic deformation of the tie bar. open. Then, for example, in the case of a vertical molding machine, the movable platen falls. Further, when molding is performed using the core, the motor driving the core is also stopped, so that the mold opens without the core retracting, and the core is damaged. It is difficult to directly stop such a ridiculous movement of the movable board because the power magnification rate of the toggle mechanism is large. In general, it may be desirable to stop the crosshead of the toggle mechanism or to use a motor with a brake to drive the toggle mechanism. However, since a plurality of long and short toggle links extend around the crosshead, it is difficult to secure a space for installing the braking device. In addition, a motor with a brake is very expensive and increases the cost of the molding machine. Such a mold opening prevention device is proposed by patent documents 1-3.

JP-A-8-244083 JP 2006-51754 A JP 2009-286137 A

Patent Document 1 discloses a mold clamping device in which an offset amount of a toggle link mechanism of a toggle type mold clamping device can be set. If the offset amount is set to near 0 mm, the mold will continue to be clamped when the power is cut off. However, if the power is cut off, the motor will rotate in the loosening direction and the toggle link mechanism will be offset. Move to stop and stop.
The mold opening prevention device of the electric toggle type mold clamping device described in Patent Document 2 includes a shutter at the tip of a ball screw that drives the crosshead of the toggle mechanism. This shutter is raised when the mold is opened, and lowered after completion of mold closing / clamping so as to come into contact with the tip of the ball screw. Therefore, when electricity is cut off due to a power failure or the like, the movable plate tends to be pushed back by the restoring force of the tie bar, the reaction force of the resin pressure, etc., but since the tip of the ball screw hits the shutter, the mold opening is prevented. .
Patent Document 3 shows an electric vertical mold clamping device in which a brake device is provided at the tip of a ball screw that drives a toggle link of the toggle mold clamping device, that is, a cross head. The brake device is released when the toggle driving motor is energized, and is braked when a power failure occurs. Also, during operation, the planned rotation speed is compared with the actual rotation speed detected by the sensor, and when the actual rotation speed is abnormally decreased, the energization to the electromagnet is stopped to prevent the ball screw from rotating. Yes.

  In the mold clamping device described in Patent Document 1, when the offset amount is set to be close to 0 mm, the mold continues to be clamped even when the power is cut off. On the other hand, if it is set larger, the motor rotates in the loosening direction when the power is cut off, and the toggle link mechanism moves so as to increase the offset amount and stops. Therefore, even if left for a long time, the oil film of the toggle bushing of the toggle link mechanism does not break, and the effect that the mold opening / closing does not become difficult when the power is restored is recognized. However, since it is controlled by the offset amount of the toggle link mechanism, malfunction may occur, and if the friction coefficient of the toggle link mechanism is low, mold opening cannot be reliably prevented, and its reliability There is an inconvenience.

The mold opening prevention device described in Patent Document 2 is a kind of mechanical braking because the movement of the ball screw that drives the crosshead of the toggle mechanism in the mold opening direction is blocked by a shutter. However, the advantage of working reliably is recognized. However, there are problems. For example, the restoring force of the tie bar and the reaction force of the resin pressure are extremely large, but a shutter that directly stops the movement of the ball screw to which this large force acts has to be large in terms of strength or structure. It is difficult to provide a large structure inside a toggle mechanism in which a plurality of toggle links are complicated. It seems impossible to establish a new toggle mechanism.
The brake device described in Patent Document 3 is released when the toggle driving motor is energized, and is braked when a power failure occurs. Therefore, mold opening during a power failure is prevented, and the rotational speed of the ball screw is reduced. In such a case, it can be determined that slip has occurred due to belt breakage or belt slack. However, similar to the shutter of the mold opening prevention device described in Patent Document 2, the brake device is provided inside the toggle mechanism, and thus is limited in size. For example, when a brake disk has to be provided separately, the disk has a small diameter, i.e., a small moment during braking, and requires a strong brake pad pressing force. In particular, it cannot be applied to existing toggle mechanisms at low cost.

  An object of this invention is to provide the molding machine which eliminated the fault of the above conventional mold opening prevention apparatuses. Specifically, an object of the present invention is to provide a molding machine having a toggle type clamping device that has a large braking effect, can be easily applied to an existing toggle type clamping device, and has a simple structure and is inexpensive. .

  The above-mentioned object of the present invention is achieved by providing a brake disk action to the rim of the passive large pulley attached to the ball screw. In the toggle type mold clamping device, the power transmission member from the mold opening / closing motor to the ball screw includes a small pulley on the driving side attached to the output shaft of the motor, a large pulley on the passive side attached to the ball screw, and the like. Of these members, a member having a large moment during braking or a member having a large rotation diameter is a large pulley on the passive side. This is because it is located outside the toggle mechanism composed of the toggle link of the book and the rim of the large pulley can have a brake disk action.

  That is, in order to achieve the above object, the toggle mechanism of the mold clamping device for opening and closing the mold has a ball screw and a ball nut, and the ball screw is a small screw on the drive motor side. In the molding machine, which is rotationally driven in a predetermined direction via a belt wound around a pulley and a large pulley on the ball screw side, thereby opening and closing the mold. The electromagnetic brake that brakes the mechanism is provided so that the brake pad acts on the rim side of the large pulley. According to a second aspect of the present invention, the brake pad of the electromagnetic brake according to the first aspect is provided so as to act on the rim side of the large pulley on the opposite side of the toggle mechanism.

  According to a third aspect of the present invention, a toggle mechanism of a mold clamping device for opening and closing a mold includes a ball screw and a ball nut, and the ball screw includes a small pulley on the drive motor side and a large pulley on the ball screw side. In a molding machine that is rotationally driven in a predetermined direction via a belt that is looped between the two and the mold is opened and closed, an electromagnetic brake that brakes the toggle mechanism is: The brake pad is provided on the opposite side of the toggle mechanism so as to act on a dedicated brake disc attached to the rim side of the large pulley. According to a fourth aspect of the present invention, the brake pad of the electromagnetic brake in the molding machine according to any one of the first to third aspects acts by a restoring force of a spring when the power of the motor is lost or when power supply is stopped. The invention according to claim 5 is configured such that a core is used for the mold in the molding machine according to any one of claims 1 to 4.

As described above, according to the present invention, the electromagnetic brake for braking the toggle mechanism is provided so that its brake pad acts on the rim side of the large pulley on the ball screw side, or on the rim side of the large pulley. Since it is provided to act on the dedicated brake disc attached, the braking moment is large and the braking effect is great. Therefore, the electromagnetic brake can be configured compactly. In general, the large pulley on the ball screw side is located outside the toggle mechanism consisting of multiple toggle links, or the brake pad is attached to the rim side of the large pulley on the opposite side of the toggle mechanism. Therefore, the present invention can be easily applied to an existing toggle type mold clamping device without being obstructed by the toggle mechanism. That is, it can be applied at low cost without changing the design of an existing toggle type mold clamping device.
Further, according to another invention, braking is applied by the restoring force of the spring when the power is lost, so that the mold does not open even if the power is lost at the time of mold clamping, for example. The effect of not damaging the core is further obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the injection molding machine which concerns on embodiment of this invention, The (a) is a front view which shows the whole, The (a) is an enlarged side view seen in the arrow A direction in (a), The (c) (A) is an enlarged plan view similarly viewed in the direction of arrow B.

  Hereinafter, embodiments in which the present invention is implemented by an injection molding machine will be described. The injection molding machine is composed of an injection unit 1 and a mold clamping unit 10 as shown in FIG. The injection unit 1 includes a heating cylinder, a screw that can be driven in the rotation direction and the axial direction in the heating cylinder, an injection nozzle that is provided at the tip of the heating cylinder, and the like. Since the unit 1 itself is conventionally known, only the injection nozzle 2 is shown in FIG.

  The main body of the mold clamping unit 10 according to the present embodiment is configured in substantially the same manner as a conventional one. That is, the fixed platen 11 fixed on the bed, the mold clamping housing 14 provided on the bed so as to be movable in the axial direction at an interval from the fixed platen 11, and between the fixed platen 11 and the mold clamping housing 14. .. Are driven in the mold closing direction or mold opening direction by the four tie bars 12, 12,... Provided by the four tie bars 12, 12,. It is composed of a toggle mechanism 20 and the like.

  Since the toggle mechanism 20 has a conventionally well-known structure, it will not be described in detail. However, in the embodiment shown in FIG. 1A, the cross mechanism 21 generally includes one cross head 21 and a pair of cross links. Similarly, it is composed of a pair of short links 23, 23, a pair of long links 24, 24, and the like. An end portion of the cross link is rotatably coupled to the cross head 21 by a pin. At the other end of the cross link, the ends of the short links 23, 23 are rotatable by pins, and at the ends of the short links 23, 23, the ends of the pair of long links 24, 24 are rotatable by pins Are coupled to each other. The other ends of the long links 24 and 24 are coupled to the brackets 25 and 25 of the movable platen 13 by pins, and the other ends of the short links 23 and 23 are the same as the brackets 26 and 26 of the mold clamping housing 14. It is connected with a pin by a pin.

  A through hole is formed in a substantially central portion of the mold clamping housing 14, and a ball screw 30 is inserted through the through hole. The ball screw 30 can rotate with respect to the mold clamping housing 14 but is supported by a bearing in a bearing case 15 provided in the mold clamping housing 14 in a state where movement in the axial direction is restricted. On the other hand, a ball nut 31 is screwed in the vicinity of the tip of the ball screw 30. The ball nut 31 is attached to the cross head 21. Therefore, when the ball screw 30 is driven to rotate, the ball screw 30 is restricted from moving in the axial direction, so that the ball nut 31 and thus the cross head 21 are driven in the mold closing direction or mold opening direction.

  As shown in FIGS. 1A and 1C, one passive large pulley 33 is integrally attached to the ball screw 30 outside the mold clamping housing 14. On the other hand, two electric motors 34, 34 for opening and closing the mold are installed on the outer side of the mold clamping housing 14, as shown in FIG. As shown in FIG. 1A, a small pulley 35, 35 on the drive side is attached to the output shafts of these motors 34, 34, and between the large pulley 33 and the small pulleys 35, 35. Two drive belts 36 and 36 are respectively wound around. The large pulley 33 is approximately twice the width of the drive belt 36, and the two drive belts 36, 36 are arranged in the axial direction as shown in FIGS. They are wound around the large pulley 33 in a shifted state and do not interfere with each other.

  One end of the tie bars 12, 12,... Is passed through the four corners of the fixed platen 11 and fixed to the fixed platen 11. The other ends of the tie bars 12, 12,... Penetrate through the four corners of the mold clamping housing 14 and extend to the outside. In addition, on the outside of the mold clamping housing 14, screws are formed on the tie bars 12, 12,..., And tie bar nuts 16, 16,. A driven sprocket is fixed to each of these tie bar nuts 16, 16,. On the other hand, a motor 17 for adjusting the mold thickness is mounted on the side of the mold clamping housing 14 as shown in FIG. 1A, and a drive sprocket 18 provided on the output shaft of the motor 17 is mounted. And a chain 19 is hung around the driven sprockets of the tie bar nuts 16, 16,. Therefore, when the electric motor 17 rotates in the forward or reverse direction, the mold thickness adjusting tie bar nuts 16, 16,... Are driven in the forward or reverse direction, and the mold clamping housing 14 includes the fixed platen 11, the movable platen 13, and the like. It moves in the direction in which the mold thickness increases or the direction in which the mold thickness decreases.

  Next, an embodiment of the electromagnetic brake will be described. In the present embodiment, the passive large pulley 33 is located outside the toggle mechanism 20, and the rim having a large rotation diameter of the large pulley 33 is used as a brake disk. As shown in FIGS. 1A and 1C, it is provided outside the large pulley 33. That is, in consideration of force balance, two units are provided on the side of the large pulley 33 with an interval of 180 degrees.

  Brackets 55 and 55 that respectively support the two electromagnetic brakes 50 and 50 extend outward from the back surface of the mold clamping housing 14. In FIG. 1C, it is shown extending downward. And the electromagnetic brakes 50 and 50 are attached to the front-end | tip. When attached, the brake pads 51 and 51 face the rim of the large pulley 33 so that the distance can be adjusted. The facing state is shown in FIG. As the electromagnetic brakes 50, 50, a type that applies braking when energized can be applied. However, in this embodiment, when DC power is supplied by the cables 52, 52, the braking is released, and when the power is lost, the spring is A type that is braked by a restoring force is applied.

  The operation of the above embodiment will be described. The injection unit 1 plasticizes the injection material as is well known. The mold thickness is adjusted by driving the motor 17 for mold thickness adjustment. Use a core if necessary. The electric motors 34 and 34 for opening and closing the mold are activated. Since the electromagnetic brakes 50 and 50 are also supplied with power, the brake pads 51 and 51 are separated from the rim of the large pulley, and the braking is in a released state. The ball screw 30 is driven to rotate in the mold clamping direction via a large pulley 33. Although the ball screw 30 rotates, the ball nut 31 screwed with the ball screw 30 cannot rotate, and thus moves in the axial direction. That is, the cross head 21 is driven in the mold clamping direction. Thereby, mold clamping is performed. Injection material is injected and filled from the injection unit 1 into the mold clamped. After cooling and solidification, the electric motors 34 and 34 for opening and closing the mold are reversed. This time, the crosshead 21 is driven in the opposite direction and the mold is opened. The molded product is ejected from the ejector pin.

  When the molding is performed as described above, for example, when the power source is lost during mold clamping, injection filling, or pressure holding, the magnetic force of the electromagnetic brakes 50 and 50 also disappears. The force is pressed against the rim of the large pulley 33 and braking is applied. This prevents the movable platen 13 or the movable mold from being opened carelessly. Safety is maintained and the core is not damaged.

  As described above, according to this embodiment, the rim of the large pulley 33 also functions as a brake disk, that is, the brake is applied to a member having a large rotation diameter during braking. The effect is great. In addition, since the electromagnetic brakes 50 and 50 are provided outside the mold clamping housing 14, in other words, outside the toggle mechanism 20, mounting is not restricted. That is, there is an effect that can be applied as it is without taking any allowance such as changing the design of an existing mold clamping unit.

  The present invention is not limited to the above embodiment and can be implemented in various forms. For example, another member such as a rib can be attached to the hub of a large pulley to form a brake disk. In this way, the brake disc can be sandwiched between the brake pads from both sides during braking. Moreover, in the said embodiment, although the large pulley 33 is comprised from one piece, two large pulleys 33 and 33 are provided, it is made to provide mutually offset in the ball screw 30, and each large pulley 33, 33, one small pulley 35 may be associated with the drive belt 36. In this case, it is only necessary to provide the electromagnetic brakes 50, 50 only to one of the two large pulleys 33, 33 so as to apply the braking. As for the one large pulley 33, it may be the large pulley 33 located on the outside, or may be the inside large pulley 33 when there is a sufficient space.

  In the above embodiment, the electromagnetic brake is braked at the time of a power failure, but it can be energized to apply the brake. In addition, for example, braking can be applied to stop the unnatural movement of the movable platen 13 other than mold clamping, for example, during maintenance inspection. Furthermore, when an abnormal rotation of the ball screw 30 is detected during mold clamping, the mold clamping operation can be stopped and braking can be applied.

10 Clamping unit 20 Toggle mechanism 21 Cross head 30 Ball screw 31 Ball nut 33 Large pulley on the passive side 36 Belt 50 Electromagnetic brake 51 Brake pad

Claims (5)

A toggle mechanism of a mold clamping device for opening and closing a mold has a ball screw and a ball nut, and the ball screw is wound around a small pulley on the drive motor side and a large pulley on the ball screw side. In a molding machine that is rotationally driven in a predetermined direction via a belt, whereby a mold is opened and closed,
An electromagnetic brake that applies braking to the toggle mechanism is provided such that a brake pad acts on a rim side of the large pulley.   2. The molding machine according to claim 1, wherein the brake pad of the electromagnetic brake is provided on the opposite side of the toggle mechanism so as to act on the rim side of the large pulley. A toggle mechanism of a mold clamping device for opening and closing a mold has a ball screw and a ball nut, and the ball screw is wound around a small pulley on the drive motor side and a large pulley on the ball screw side. In a molding machine that is rotationally driven in a predetermined direction via a belt, whereby a mold is opened and closed,
The electromagnetic brake for braking the toggle mechanism is provided such that the brake pad acts on a dedicated brake disc attached to the rim side of the large pulley on the opposite side of the toggle mechanism. And molding machine.   The molding machine according to any one of claims 1 to 3, wherein the pad of the electromagnetic brake acts by a restoring force of a spring when the power of the motor is lost.   The molding machine according to any one of claims 1 to 4, wherein a core is used for the mold.

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