JPH06126789A - Injection compression molding machine - Google Patents

Abstract

PURPOSE:To provide an injection compression molding machine which is capable of decreasing the number of a driving source and of reducing the weight of a mechanism placed on a movable die plate and cost by sharing the driving source with a compression mechanism and an ejection mechanism. CONSTITUTION:A pin 17 for compression is advanced through a first rotation- rectilinear conversion mechanisms 9, 14 and also an ejection pin 19 is retreated through a second rotation-rectilinear conversion mechanisms 7, 15 by reverse rotation of a servomotor 3. Further the pin 17 for compression is retreated through the first rotation-rectilinear conversion mechanisms 9, 14 and also the ejection pin 19 is advanced through the second rotation-rectilinear conversion mechanisms 7, 15 by normal rotation of the servomotor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding machine,
In particular, it relates to an injection compression molding machine in which the drive source of the compression mechanism and the drive source of the eject mechanism are shared.

[0002]

2. Description of the Related Art In an in-line screw type injection molding machine, generally, after a molten resin is injected and filled into a mold (after primary injection), a forward pressure is applied to the screw in order to compensate for shrinkage of the resin due to temperature change. The molten resin is continuously fed into the mold from the tip of the nozzle (so-called pressure holding is performed). By this holding pressure, a compressive stress is locally applied from the gate portion in the mold to the molten resin portion in the cavity,
The compressive stress due to the holding pressure mainly concentrates locally on the gate part, and the compressive stress does not reach the resin part that started to solidify first at the part in contact with the inner wall (mold surface) of the cavity. May not achieve the required molded product quality.

Therefore, before the mold is opened after injection / filling (after the primary injection), compressive stress is applied to the resin in the mold from the side opposite to the nozzle injection part by the compression pressing member, that is, by the compression pin, for example. Compressive stress is applied to the resin inside the mold through the core mold that can move back and forth, and by doing so, compressive stress is applied to each part of the resin part that has started to solidify and is in contact with the inner wall of the cavity. Various types of injection compression molding machines have been proposed and put into practical use, which are designed to mold products with good appearance accuracy.

In such a conventional injection compression molding machine, a compression driving source such as a compression cylinder (hydraulic cylinder) and a compression pressing member are mounted on a movable die plate to which a movable mold is attached. At the same time, an ejecting drive source such as a cylinder for ejecting a product (hydraulic cylinder) and an ejecting member are mounted, and a compressing driving source drives a compressing pressing member such as a compressing pin to add compressive stress to the resin. In general, the ejecting drive source drives an eject member such as an eject pin to eject a product from a mold.

[0005]

However, as described above, when the compression drive source and the eject drive source are mounted on the movable die plate, it is necessary to form a double hydraulic cylinder structure in which the two drive sources are coaxially arranged, for example. However, there is a problem that the structure of the driving source becomes complicated, and since there are two driving sources, the structure becomes large and the cost increases.

The eject pin (eject member)
There is also known a configuration in which a compressive stress is applied to the resin by using the eject pin, but in general, the eject pin is generally thin, and in such a case, the compressive stress cannot be applied to the resin in a relatively wide range. Therefore, it is unavoidable to provide a separate compression pressing member.

The present invention has been made in view of the above points,
The purpose is to reduce the number of drive sources by sharing the drive source of the compression mechanism and the eject mechanism.
An object of the present invention is to provide an injection compression molding machine capable of reducing the mechanical weight mounted on the movable die plate and reducing the cost.

[0008]

In order to achieve the above-mentioned object, an injection compression molding machine according to the present invention includes a motor which is a rotary drive source capable of rotating in the forward and reverse directions of a first direction and a second direction. A first rotation-linear conversion mechanism that converts the rotational force of the motor into a linear motion, a second rotation-linear conversion mechanism that converts the rotational force of the motor into a linear motion, and the first rotation-linear conversion A pressing member for compression that is connected to the mechanism to move back and forth, and an eject member for ejecting a product that is connected to the second rotation-linear conversion mechanism and that moves back and forth, the first direction of the motor. Rotation to move the pressing member forward by the first rotation-linear conversion mechanism and retract the eject member by the second rotation-linear conversion mechanism, and in the second direction of the motor. By the rotation of Serial first rotation - linearity conversion mechanism by the second rotating together with the retracting the pressing member - a linear converting mechanism to advance the ejection member configured.

[0009]

The nut member of the first rotation-linear conversion mechanism (the first rotation-linear conversion mechanism) is connected to the rotating member that is integrally rotated with the output shaft of the servomotor (rotational drive source) mounted on the movable die plate.
Nut body) and the nut body (second nut body) of the second rotation-linear conversion mechanism are fixed to each other, and the first screw member is screwed into the first nut body to form the second nut. A second screw member is screwed onto the body. Then, for example, with respect to the reverse rotation of the servo motor, the first screw member of the first rotation-linear conversion mechanism moves forward, the second screw member of the second rotation-linear conversion mechanism moves backward, and the servo With respect to the normal rotation of the motor, the first screw member retracts and the second screw member advances. Therefore, by reversing the servo motor by a relatively small amount after the primary injection, the compression pressing member moves forward together with the first screw member, and the compression pressure is applied to the resin in the mold. By causing a relatively small amount of forward rotation, the eject member advances together with the second screw member, and compressive pressure is applied to the resin in the mold. On the other hand, by rotating the servomotor in a relatively large forward direction at an appropriate timing after starting the mold opening,
The eject member moves largely forward together with the second screw member to eject the product (molded product) from the mold (movable side mold). Therefore, the forward / backward movement of the pressing member for compression and the forward / backward movement of the eject member are controlled by a single servo motor, so that the number of drive sources can be reduced, the mechanical weight to be mounted on the movable die plate can be reduced, and the cost can be reduced. Can be achieved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 are explanatory views showing the outline of the compression mechanism and the eject mechanism mounted on the movable die plate in the injection compression molding machine according to the present embodiment, and FIG. 1 shows the compression pin and the eject pin at the origin position. FIG. 2 shows a certain state, FIG. 2 shows a state at the time of ejecting operation by the eject pin, and FIG. 3 shows a state in which a compressive stress is applied to the resin. FIG. 4 is an explanatory diagram showing how to apply alternating compressive stress to the resin according to the present embodiment, and FIG. 5 is an explanatory diagram showing the relationship between the rotational state of the motor and the alternating additional compressive stress caused thereby. .

1 to 3, a movable die plate is generally denoted by reference numeral 1, and the driving force of a mold clamping cylinder (hydraulic cylinder) (not shown) is transmitted through a known toggle link mechanism. It is moved back and forth in the left-right direction. That is, the movable die 2 is attached to the left side surface of the movable die plate 1 in the drawing, and the movable die plate 1 is driven forward to the left in the drawing during the die closing operation to move the movable die 2
To the fixed die attached to a fixed die plate (not shown), and during the mold opening operation, the movable die plate 1 is driven backward to the right in the figure to separate the movable die 2 from the fixed die. It is designed to let you.

Reference numeral 3 is a servo motor mounted on the movable die plate 1, and an output shaft 3a thereof has a toothed output pulley 4 fixed thereto. Reference numeral 5 denotes a compound rotary member to which the rotation of the servomotor 3 is transmitted, and includes a toothed driven pulley 6, a second nut body 7, a connecting rotary body 8, and a first nut body 9,
Each of the members 6 to 9 is integrated so as to rotate integrally. Reference numeral 10 denotes a support member attached to the movable die plate 1, which rotatably holds the composite rotary member 5 via a radial bearing 11 and a thrust bearing 12. Reference numeral 13 denotes a toothed belt (timing belt) stretched between the toothed output pulley 4 and the toothed driven pulley 6, and the forward / reverse rotation of the servomotor 3 is a combined rotation via the toothed belt 13. It is adapted to be transmitted to the member 5.

Reference numeral 14 is a hollow first screw member.
The threaded portion 14a of the threaded member 14 (for example, the threaded part formed in the present embodiment has a left-hand thread) is screwed into the first nut body 9, and the first nut body 9 and the first threaded member 14 are joined together.
And constitute a first rotation-linear conversion mechanism for moving the compression pin 17, which will be described later, back and forth. 15
Is a second screw member whose tip side is inserted through the first screw member 14, and the screw portion 15a of the second screw member 15 (for example, one formed with a right screw in the present embodiment) is the second screw member. The second nut body 7 and the second screw member 15 are screwed to the nut body 7, and constitute a second rotation-linear conversion mechanism for moving the eject pin 19 described later forward and backward. . In the present embodiment, the known ball screw mechanism is adopted as the first and second rotation-linear conversion mechanisms, but any screw coupling mechanism can be used. In addition, in the present embodiment, the first screw member 14 and the second screw member 15 are connected to each other as described above.
By adopting the heavy shaft structure, the mechanism is made compact and the space efficiency of the member arrangement on the movable die plate 1 is improved.

As described above, since the first screw member 14 and the second screw member 15 are in the opposite screw direction to each other, in this embodiment, the reverse rotation of the servomotor 3 causes the first screw member to rotate. 14 moves forward (to the left in the drawing) and the second screw member 15 moves backward (to the right in the drawing), while the forward rotation of the servomotor 3 causes the first screw member 14 to rotate.
And the second screw member 15 moves forward. Further, in this embodiment, the first screw member 14
The ratio of the screw lead of the second screw member 15 to that of the second screw member 15 is set to, for example, 1: 2.
It is configured so that it can be linearly moved by an amount twice that of the screw member 14.

Reference numeral 16 denotes a compression plate fixed to the tip side of the first screw member 14, and a plurality of compression pins 17 are planted and fixed to the compression plate 16 for compression. The pin 17 is slidable inside the movable mold 2. Reference numeral 18 denotes an eject plate fixed to the tip end side of the second screw member 15 having the first screw member 14 and the compression plate 16 inserted therethrough, and the eject plate 18 has a plurality of eject pins 19. Are planted and fixed, and the eject pin 19 is also slidable in the movable mold 2.

Next, the operation based on the above configuration will be described. First, the eject operation will be described. When the molded product (resin) in the mold (cavity) is solidified and cooled,
The mold opening is started and the movable die plate 1 is driven in the releasing direction, and accordingly, the movable side mold 2 is separated from the fixed side mold with the molded product attached. The eject operation is started during the mold opening process or after the mold opening is completed.
The system controller of the machine (injection molding machine) instructs the servomotor 3 to rotate in the normal rotation direction, and the servomotor 3 starts normal rotation (at the start of the eject operation,
The compression pin 17 and the eject pin 19 are at the origin position in FIG. 1). When the servomotor 3 normally rotates, as described above, the first screw member 14 of the first rotation-linear conversion mechanism is retracted, and the compression plate 16 and the compression pin 17 which are integral with this are retracted, Further, the second screw member 15 of the second rotation-linear conversion mechanism advances, and the eject plate 18 and the eject pin 19 integrated with the second screw member 15 advance.

FIG. 2 shows a state at the time of this ejecting operation. As shown in the figure, the ejecting pin 19 advances to separate a molded product (product) (not shown) from the movable side mold 2. Stick out. Since the ratio of the screw lead of the first screw member 14 and the screw lead of the second screw member 15 is set to 1: 2 as described above, the advance amount of the second screw member 15 is the first amount. The amount of retreat of the screw member 14 is doubled, and high-speed eject operation is possible although the torque is relatively low. Further, the normal rotation amount of the servo motor 3 during the eject operation is significantly larger than the reverse rotation amount or the forward rotation amount during the compression stroke described later.

Next, the compression operation will be described. In this embodiment, in order to apply a compressive stress to the resin in the mold, the pressing force by the compression pin 17 and the pressing force by the eject pin 19 are used alternately (switched periodically). There is.

In a mold clamped state in which the movable mold 2 and the fixed mold are in close contact with each other with a predetermined mold clamping force, from the nozzle at the tip of the heating cylinder in close contact with the resin injection port of the fixed mold, Primary injection is performed by injecting and filling the molten resin into the cavity, which is a space for product formation, by high-speed advance of the screw. After this primary injection, a forward pressure is applied to the screw to hold the molten resin continuously from the nozzle into the cavity. A holding operation is performed in parallel with the holding pressure. At the time of this compression stroke, the system controller of the machine instructs the servomotor 3 to alternately repeat the reverse rotation and the forward rotation, whereby in this embodiment,
The servomotor 3 repeats reverse rotation and stop and forward rotation and stop at a cycle of 0.1 to several seconds, for example. Before the compression operation is started, the compression pin 17 and the eject pin 19 are different from those in FIG.
It is at the origin position.

As a result, when the servo motor 3 rotates in the reverse direction, the first screw member 14 of the first rotation-linear conversion mechanism advances by a predetermined amount, and the compression pin 17 advances accordingly, for example, Resin inside the cavity through the core mold in the movable mold 2 (resin that has started to solidify at the outer peripheral portion inside the cavity; solidification that is in contact with the core mold that forms a part of the outer shape of the cavity) Resin) with compressive stress. The position of the compression pin 17 is maintained only for a predetermined time after advancing, and after that, the servo motor 3 is driven in the normal direction according to a command from the system controller. During the normal rotation of the servomotor 3, the second screw member 15 of the second rotation-linear conversion mechanism advances by a predetermined amount, and accordingly, the eject pin 19 advances and the eject pin 19 advances.
The tip of the above applies compressive stress to the resin inside the cavity (the resin that has started to solidify at the outer peripheral portion inside the cavity) at a plurality of points.
Similarly, the eject pin 19 is made to maintain its position after advancing only for a predetermined time. Thereafter, the servomotor 3 is driven in reverse by a command from the system controller, the compression pin 17 moves forward again, and compression stress is applied to the resin by the compression pin 17. After that, the servo motor 3 is similarly made to repeat normal rotation and reverse rotation at a predetermined time interval, and the compression pin 17 (core die) and the eject pin 19 alternate between the outer peripheral portion in the cavity. Compressive stress is applied to the resin that has started to solidify. FIG. 3 shows a state during this compression operation.

Next, referring to FIGS. 4 and 5, the manner in which the alternating compressive stress is applied to the resin in the mold will be described. FIG. 4 is a diagram schematically showing the mechanism around the mold. The diagram is simplified for convenience of illustration, but the drive mechanism of the compression pin and the eject pin is shown in FIGS.
The mechanism is basically the same. In FIG. 4, 2A, 1
7A and 19A are movable molds, compression pins, and eject pins corresponding to those in FIGS. 1 to 3, and 20 is a core mold that can be moved back and forth by a predetermined amount in the movable mold 2A. Two
1 is a fixed side mold, 22 is a movable side mold 2A (core mold 20
) And a fixed-side mold 21.
Reference numeral 23 is a heating cylinder, 24 is a screw, 25 is a nozzle portion pressed against the resin injection port of the stationary mold 21, and 26
Reference symbol a is a molten resin, and reference symbol 26b is a resin that has started to solidify.

As is known, injection into the cavity 22
The filled molten resin begins to solidify from the portion in contact with the mold, and the solidification gradually proceeds inside. The pressing force exerted by the compression pin 17A through the core die 20 is the eject pin 1
In the state in which 9A is retracted, it acts on the resin 26b that has started to solidify and is in contact with the core die 20 to apply compressive stress, and the pressing force by the eject pin 19A is In the retracted state, the compressive stress is exerted by acting on the resin 26b which has started to solidify and is in contact with the tip end surface of the eject pin 19A. By alternately and repeatedly applying a compressive stress to different portions of the resin 26b which has started to solidify, the molecular orientation of the polymer of the resin 26b and the molten resin 26a which has started to solidify effectively. It becomes possible to change to the above, and the polymer can be easily entangled in the resin during the solidification process, and the bond strength can be increased.

FIG. 5 shows the relationship between the rotation state of the servomotor 3 and the compressive stress applied to the resin in the mold.
In this embodiment, the amount of reverse rotation from the origin is made larger than the amount of normal rotation from the origin, and the compression force by the compression pin 17A (core die) is set to be larger than that by the eject pin 19A. I am doing it. Needless to say, the magnitude relationship between the compression force of the compression pin (core die) and the compression force of the eject pin can be set arbitrarily.

As described above in detail, in this embodiment, the ejecting operation and the compressing operation are performed by the driving force of a single servo motor, so that the number of driving sources can be reduced and the movable operation can be performed. It is possible to reduce the weight of the mechanism mounted on the die plate and reduce the cost.

In the above-described embodiment, the pressing force by the compression pin and the pressing force by the eject pin are used alternately to apply the compressive stress to the resin in the mold, but the compression operation is Needless to say, it may be performed only by the compression pin.

[0026]

As described above, according to the present invention, it is possible to reduce the number of drive sources by sharing the drive source for the compression mechanism and the eject mechanism, thereby reducing the weight of the mechanism mounted on the movable die plate and reducing the cost. The injection compression molding machine can be provided and its value is great.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an origin position state of a main part mechanism mounted on a movable die plate in an injection compression molding machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state during an ejecting operation by a main part mechanism mounted on a movable die plate in an injection compression molding machine according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a state during a compression operation by a main part mechanism mounted on a movable die plate in an injection compression molding machine according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing how alternating compression stress is applied to the resin in the mold according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the relationship between the rotation state of the servo motor and the compressive stress applied to the resin in the mold according to the first embodiment of the present invention.

[Explanation of symbols]

 1 Movable Die Plate 2, 2A Movable Side Mold 3 Servo Motor 4 Toothed Output Pulley 5 Composite Rotating Member 6 Toothed Driven Pulley 7 Second Nut Body 8 Connection Rotating Body 9 First Nut Body 10 Supporting Member 11 Radial Bearing 12 Thrust Bearing 13 Toothed Belt (Timing Belt) 14 First Screw Member 15 Second Screw Member 16 Compression Plate 17,17A Compression Pin 18 Eject Plate 19,19A Eject Pin 20 Core Mold 21 Fixed Side Mold 22 Cavity 23 Heating cylinder 24 Screw 25 Nozzle portion 26a Molten resin 26b Resin that has started to solidify

Claims (3)

[Claims] 1. A motor, which is a rotational drive source capable of rotating in the first and second directions, and a first rotation-linear conversion mechanism for converting the rotational force of the motor into a linear motion. A second rotation-linear conversion mechanism that converts the rotational force of the motor into a linear motion, a compression pressing member that is connected to the first rotation-linear conversion mechanism and moves back and forth, and the second rotation-linear An ejecting member for projecting the product, which is connected to the converting mechanism and moves back and forth. The rotation of the motor in the first direction causes the pressing member to move forward by the first rotation-linear conversion mechanism. The eject member is retracted by the second rotation-linear conversion mechanism, and the pressing member is retracted by the first rotation-linear conversion mechanism by the rotation of the motor in the second direction. Second Rolling - injection compression molding machine is characterized in that so as to advance the ejection member by the linear conversion mechanism. 2. The first rotation-corresponding to the constant rotation amount of the motor according to claim 1, wherein the linear movement amount by the linear conversion mechanism corresponds to the same rotation amount by the motor. An injection compression molding machine characterized by being set smaller than the linear movement amount by the linear conversion mechanism. 3. The double screw shaft according to claim 1, wherein the screw member moving forward and backward in the first rotation-linear conversion mechanism and the screw member moving forward and backward in the second rotation-linear conversion mechanism are double shafts. An injection compression molding machine characterized by having a structure.