JP3712331B2 - Core compression injection molding machine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a core compression injection molding machine that uses a spring for clamping.
[0002]
[Prior art]
An injection molding machine using a servo motor as a driving source for each process is widely used at present. However, if one servo motor is used for every operation mechanism, the number of servo motors is too large, resulting in an enormous cost of the apparatus, and the control apparatus becomes more complicated and causes a failure.
[0003]
In injection molding, the mold is clamped with an appropriate clamping force, and after filling the mold cavity with resin, the molded product is taken out by holding and cooling. Since a high clamping pressure that does not lose the pressure is required, this is one cause of mold breakage. In addition, when the resin is filled, it is necessary to easily dissipate the internal gas from the mold in order to prevent the generation of voids. Outgassing becomes difficult.
[0004]
In addition, the resin is weighed and the amount of resin to be filled is filled in the mold cavity, but the kneading state of the raw material resin depends on various factors including changes in the ambient temperature surrounding the injection molding machine. Variations occur in the filling state, and a situation such as overfilling or insufficient filling occurs. If overfilling occurs, the molded product will not come out of the mold, and especially in the case of optical molded products such as disk substrates, there is a problem that the optical properties will deteriorate, and you want to avoid overfilling as much as possible. In the injection filling and pressure holding process, it is necessary to fasten the mold with a predetermined clamping force, and there is no problem of resin escape in the injection filling process, and there is a problem that it easily falls into overfilling.
[0005]
[Problems to be solved by the invention]
The problems to be solved by the present invention are as follows: (a) overfilling of the mold cavity can be eliminated and appropriate filling is always obtained, and (b) excessive pressure is applied to the mold in spite of mold compression. No need to squeeze, no damage to mold, (c) excellent gas escape, (d) excellent core compression injection molding machine that can perform mold clamping and core compression with one servo motor Is in development.
[0006]
[Means for Solving the Problems]
“Claim 1” is the basis of the core compression injection molding machine (A) according to the present invention, “the mold (1) in which the core mold (5) is disposed, and the filling resin (3) is compressed. A core compression injection molding machine (A) having a mold mounting plate (D) in which a core compression plate (6) for pressing the core mold (5) in the direction of (9) is disposed between the core compression plate (6) and the mold mounting plate (D), the core compression plate (6) via the elastic body (9) the mold ( 1b) is pressed in the closing direction ".
[0007]
According to this, when the core compression plate (6) is pressed and clamped, the male and female molds (1a) and (1b) first contact each other via the elastic body (9), and when pressed further, the core mold (5 ) Is pressed and the filled resin (3) inside is compressed, and clamping and core compression are possible with one drive part (T).
[0008]
In this case, since the male and female molds (1a) and (1b) are clamped by the elastic body (9), when the filling resin (3) is excessively filled, the elastic body (9) Bends momentarily, and then gradually pushes the filling resin (3) back toward the sprue (46) by the elastic force. As a result, the excessively filled resin (3) is eliminated to obtain an appropriate resin amount, and the core compression in the overfilled state is avoided.
[0009]
Further, since the mold clamping is performed by the elastic body (9), when the gas is accumulated in the mold cavity (2) and the internal pressure is increased, the elastic body (9) is naturally bent and gas is released. In addition, since the core is compressed, resin pressure hardly acts on the movable mold (1b) containing the core mold (5), so clamping with a small pressure by the elastic body (9) is sufficient. The male and female molds (1a) and (1b) are not damaged by the clamping force.
[0010]
The core mold (5) may be provided on the movable mold (1b) side or on the fixed mold (1a) side, depending on the design of the mold (1). ) May be installed. In the embodiment shown in the figure, an example is shown in which it is installed on the moving mold (1b) side.
[0011]
“Claim 2” is defined as “Claim 2”. “Claim mold (1a) and moving mold (1b) in which core mold (5) is disposed, and fixed mold (1a)”. A fixed die plate (17) for mounting and a core compression plate (6) for pressing the core mold (5) in the direction of compressing the filling resin (3) are disposed inside, and the moving mold (1b) In a core compression injection molding machine (A) having a movable die plate (18) to which is attached, an elastic body (9) is disposed between the core compression plate (6) and the movable die plate (18). The core compression plate (6) presses the movable mold (1b) in the closing direction via the elastic body (9) . "
[0012]
“Claim 3” specifically defines the core compression injection molding machine (A) of the present invention, “a moving mold in which a fixed mold (1a) and a core mold (5) are disposed. (1b) and a fixed die plate (17) for mounting the fixed die (1a) and a core compression plate (6) for pressing the core die (5) in the direction of compressing the filling resin (3) are arranged inside. A movable die plate (18) to which the movable mold (1b) is attached, and an elastic body (9) disposed between the core compression plate (6) and the movable die plate (18). If, have a said elastic member (9) by reciprocating the movable die plate (18) via and core mold (5) directly pressing driving unit (T), the core compression plate (6) The moving mold (1b) is pressed in the closing direction via the elastic body (9) ”.
[0013]
“Claim 4” relates to the elastic body (9) and is characterized in that “the elastic body (9) is a compression coil spring”.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail according to illustrated embodiments. FIG. 1 is an overall schematic view of an injection molding machine (A) of the present invention. (a) is an injection mechanism unit, which integrally includes an injection cylinder (13), and a hopper for supplying molding material to the injection cylinder (13) on the rear upper surface of the injection cylinder (13) ( 16) is erected. A heater (14) for heating and melting a molding resin for measurement is wound around the outer periphery of the injection cylinder (13). A screw (4) is housed in the injection cylinder (13) so as to be rotatable and slidable.
[0015]
A base housing (10a) is attached to the rear end base of the injection cylinder (13), and a slide bar (21) is provided between the injection cylinder (13) and the gear box (10b) provided at the rear part. The slide housing (22) is attached to the slide bar (21) so as to be slidable back and forth.
[0016]
A driven pulley (23) is disposed at a front portion of the slide housing (22), and a rear end portion of the screw (4) is attached. The driven pulley (23) is connected to a drive pulley (25) of a screw rotating servomotor (11) via a transmission belt (24) such as a timing belt.
[0017]
On the other hand, a drive nut (27) is disposed at the rear of the slide housing (22) via a pressure sensor (15), and a drive screw (28) for screw forward / reverse drive is attached to the drive nut (27). Is screwed. A rear end portion of the drive screw (28) is rotatably supported by the gear box (10b) via a bearing, and a driven pulley (29) attached to the rear end thereof is a transmission belt such as a timing belt. The screw is connected to a drive pulley (38) of a servo motor (12) for screw advance / retreat drive via (37).
[0018]
The servo motors (11) and (12) are respectively provided with detectors (11a) and (12a) such as encoders, and exchange information with the control device (8) to provide servo motors (11 ) (12) output control.
[0019]
(b) is a mold mechanism part of the apparatus (A). The mold (1) consists of fixed and moving molds (1a) and (1b), and the fixed mold (1a) is mounted on the fixed die plate (17), which is one mold mounting plate (D). The moving mold (1b) is mounted on the moving die plate (18), which is the other mold mounting plate (D), and the core mold (5) is slidable in the moving mold (1b). It is arranged.
[0020]
A mold cavity (2) is formed on the parting surface of the fixed mold (1a), and the core mold (5) faces the mold cavity (2) in the moving mold (1b). The metering resin (3) filled in the mold cavity (2) is compressed by the mold.
[0021]
In addition, a disc-shaped metal plate called a stamper (2a) is fitted into the inner surface of the mold cavity (2) of the fixed mold (1a), and an information bit for CD or DVD, for example, is placed on the surface. Is formed as a continuous body of fine irregularities. This fine uneven surface is required to have extremely high smoothness (for example, max 0.01 μm) flatness = 0.1 μm, and parallelism is required to have extremely high accuracy, for example, 0.005 mm or less. Is done.
[0022]
At the center of the core mold (5), a hollow eject pin (30a) for product ejection and a gate cut pin (30) inserted through the hollow eject pin (30a) are slidably disposed.
[0023]
The movable die plate (18) is slidably attached to the tie bar (19). One end of the tie bar (19) is attached to the tailstock (20) and the other end is attached to the fixed die plate (17). A core compression plate (6) that constitutes a part of one mold mounting plate (D) together with the movable die plate (18) is disposed on the back surface of the movable die plate (18).
[0024]
The core compression plate (6) is slidably accommodated in a core accommodation recess (18a) formed in the movable die plate (18). A slide through hole (6a) is formed in the center, and a sleeve with a flange (51) and a ring (52) in contact with the flange are disposed in the slide through hole (6a). Has been.
[0025]
The inner diameter of the ring (52) is slightly smaller than the outer shape of the hollow eject pin (30a) so that the outer peripheral edge of the rear end surface of the hollow eject pin (30a) abuts and separates from the inner peripheral edge of the front surface of the ring (52). It has become.
[0026]
An elastic body (9) is disposed in an elastic body housing recess (9a) formed between the movable die plate (18) and the core compression plate (6). The elastic body (9) is disposed at least two or three places around the core compression plate (6) so that the core compression plate (6) is close to or away from the moving die plate (18) without being inclined. It has become.
[0027]
Further, a stopper (39) for adjusting the separation distance of the core compression plate (6) is provided between the movable die plate (18) and the core compression plate (6). The stopper (39) is composed of a collar (39a) for adjusting the separation distance and a bolt (39b) for fixing the collar (39a). The distance can be changed freely.
[0028]
That is, the collar (39a) is partly housed in a recess (6b) drilled in the core compression plate (6) and bolted, and the other end is a through-hole drilled in the movable die plate (18). (18b) is inserted. The bolt (39b) is formed with a flange (39c) so as to come into contact with and separate from the hole edge of the through hole (18b). Similarly to the elastic body (9), the stopper (39) is also disposed at least two or three places around the core compression plate (6).
[0029]
A pressure sensor (54) is disposed on the back of the core compression plate (6), and the pressure sensor (54) is attached to the movable die plate (18) via the core compression plate (6). A housing (50) is further installed on the back of the pressure sensor (54), and the housing (50) is slidably attached to the tie bar (19) together with the movable die plate (18).
[0030]
Next, it is easy to attach to the mold opening / closing toggle type mold clamping mechanism that becomes the drive part (T) that reciprocates the moving die plate (18) through the elastic body (9) and directly presses the core mold (5). Explained. The drive unit (T) is not limited to the mold opening / closing toggle type clamping mechanism, and may be any direct pressure type cylinder or any other type that can accomplish the above-described operation. Here, a mold opening / closing toggle type clamping mechanism will be described as a representative example of the drive unit (T). A mold control servo motor (31) is attached to the tailstock (20), and the drive pulley (32) attached to the rotary drive shaft and the tailstock (20) are rotatably arranged via a bearing. The driven pulley (34) provided is connected by the transmission belt (33). A pulse generator (31a) is mounted on the mold control servomotor (31).
[0031]
A male threaded rod (44) is threadably mounted on the driven pulley (34), and the projecting end of the male threaded rod (44) is attached to the mold opening / closing cross head (35). The mold opening / closing toggle has long and short arms (36) connected to a link mechanism, one end of which is pivotally connected to the tailstock (20) and the other end is pivotally connected to the housing (50). The other end is attached to the mold opening / closing cross head (35). Since this link mechanism is a known technique, further details are omitted.
[0032]
Next, the gate cut / eject mechanism (C) provided in the housing (50) will be described. A servo motor (40) for gate cut / eject is attached to the housing (50), and the drive pulley (41) attached to the rotary drive shaft and the housing (50) rotate via a bearing. A freely driven pulley (43) is connected to the transmission belt (42). A rotating housing (53) is rotatably housed in the housing (50) via a bearing, and an eject nut portion (49) is inserted and fixed in its front mounting hole (53a). A rear screw portion (48a) of the hollow screw portion (48) is screwed into the eject nut portion (49). The front end of the hollow screw portion (48) is detachably connected to the gate cut pin (30).
[0033]
An operation nut (55) is fixed to the rear portion of the rotary housing (53). The operating nut (55) is screwed with a screw portion (47a) screwed to the rear portion of the operating rod (47) so as to be able to advance and retract. The servo motor (40) is provided with a pulse generator (40a). The rear screw portion (48a) of the hollow screw portion (48) and the screw portion (47a) screwed to the rear portion of the operating rod (47) are constituted by reverse screws, and when one moves forward, the other Has come to retreat.
[0034]
A straight portion (47b) of an operating rod (47) for gate cutting is inserted into the hollow screw portion (48) so as to be rotatable and slidable. A rear screw portion (48a) of the hollow screw portion (48) is screwed into an eject nut portion (49) mounted inside the rotating housing (53). The straight portion (48b) on the mold (1) side, which is the first half of the hollow screw portion (48), slides on a flanged sleeve (51) that is slidably inserted into the core compression plate (6). The front end of the hollow eject pin (30a) is in contact with and separable from the rear end.
[0035]
Next, the operation of the device (A) will be described. On the mold (1) side, the mold clamping mechanism (T) is operated from the mold open state shown in FIG. 2, and the mold clamping is first performed as shown in FIG. That is, when the mold control servo motor (31) is operated, the rotational force is transmitted to the driven pulley (34) via the drive pulley (32) and the transmission belt (33), and the driven pulley (34) is rotated. The male threaded rod (44) advances in the right direction in the figure and pushes the cross head (35) to extend the mold opening / closing toggle (T).
[0036]
At this time, the housing (50), the pressure sensor (54), the moving die plate (18) and the moving mold (1b) mounted on the housing (50) are moved to the fixed mold (1a) side and fixed in accordance with this extension. The moving mold (1b) is pressed against the mold (1a) , and the mold is closed. Since the core compression molding is important here, no injection pressure is applied to the movable mold (1b), so that it is not necessary to strongly clamp the mold. Therefore, the mold is closed to such an extent that the elastic body (9) bends lightly. In other words, the mold clamping mechanism (T) is not in a fully extended state but is stopped in a state with a slight margin.
[0037]
As can be seen from the figure, the housing (50) to which one end of the mold clamping mechanism (T) is connected presses the core compression plate (6) via the mold side pressure sensor (54), and the core compression plate In (6), the movable mold (1b) is pressed through the elastic body (9) . On the other hand, the core mold (5) is directly pressed by the core compression plate (6) via the flanged sleeve (51) and the ring (52).
[0038]
When the mold closing shown in FIG. 3 is completed, the process proceeds to FIG. 4 where the injection servo motor (12) is operated to move the screw (4) to the mold (1) side, and the metering kneaded molten resin at the tip of the injection cylinder (13). (3) is injected into the mold cavity (2). The injection speed is optimally controlled by the control device (8). Resin pressure is applied to the core mold (5) along with injection filling, but the resin pressure is not applied to the movable mold (1b), so the mold is only closed with a small force of the elastic body (9). But there is no burr on the parting surface. Moreover, since the mold is closed by a weak mold closing force, the mold (1) can be prevented from being damaged.
[0039]
When the measured molten resin (3) is injected and filled into the mold cavity (2), a gate cut is performed as shown in FIG. That is, when the servo motor (40) is operated with the mold (1) being closed after the above resin filling, the drive pulley (41) rotates and is driven by the timing belt (42). The pulley (43) rotates. Since this driven pulley (43) is screwed into the operating rod (47) via the rotary housing (53) and the gate cut drive nut portion (55), the driven pulley (43) is rotated to rotate the operating rod (47). Advances, and the gate cut pin (30) connected thereto projects toward the gate (1c) to cut the gate.
[0040]
On the other hand, since the eject nut part (49) fixed to the rotary housing (53) is screwed into the hollow thread part (48), when the driven pulley (43) rotates, the eject nut part (49) The hollow screw part (48) also moves, but since the ejector operating rod (47) and the hollow screw portion (48) are formed in reverse threads, the operating rod (47) operates. When the gate cut pin (30) is pushed out, the hollow screw portion (48) is retracted. However, since the rear end of the hollow eject pin (30a) is locked to the front end of the ring (52), the hollow eject pin (30a) does not move backward, and a gap is formed between the hollow eject pin (30a) and the hollow screw portion (48). . When the gate cut is completed in this way, the mold cavity (2) is completely shut out from the outside.
[0041]
As described above, when the gate cut is completed, the core mold clamping is started in this state. That is, the arm of the mold clamping mechanism (T) that has been closed with a margin is extended, and the housing (50) is advanced again. As a result, the core compression plate (6) is further advanced via the pressure sensor (54), and the elastic body (9) is further bent to increase the clamping force of the mold (1). At the same time, the hollow eject pin (30a) moves forward together with the core mold (5), and the core mold is clamped.
[0042]
At this time, since the gate cut pin (30) is in the gate cut state and cannot move forward, the hollow eject pin (30a) slides forward on the outer periphery of the gate cut pin (30). Since the operating rod (47) that is in contact with the rear end of the gate cut pin (30) does not move, it is screwed into the threaded portion (47a) of the operating rod (47) as the housing (50) advances. The drive nut part (55) that is rotating reversely cancels the movement difference. As a result, the core of the filling resin (3) is compressed with extremely strong pressure, and the fine irregularities formed on the stamper (2a) are transferred to the filling resin (3) that is being cured.
[0043]
When the filling resin (3) is cured, the servo motor (31) is reversely operated to loosen the toggle mechanism (T) and move the moving mold (1b) away from the fixed mold (1a) side. At this time, the molded product (26) moves together with the moving mold (1b) while being adhered to the moving mold (1b). (See Figure 7)
[0044]
Finally, when the mold opening is finished, the gate portion (26a) attached to the tip of the gate cut pin (30) is protruded and dropped. (Refer to FIG. 8) After that, the servo motor (40) is reversed, the hollow screw portion (48) advances, and the front end of the hollow screw portion (48) then hits the hollow eject pin (30a). Extrude and eject the molded product (26). At this time, the operating rod (47) moves backward due to the reverse screw. As described above, the series of injection steps is completed.
[0045]
【The invention's effect】
In the present invention, since it is configured as described above, (a) it is possible to eliminate overfilling into the mold cavity and always obtain appropriate filling, and (b) to perform mold compression. Regardless, it is not necessary to apply excessive pressure to the mold, it does not hurt the mold, (c) is excellent in outgassing, and (d) mold clamping and core compression can be performed with one servo motor. .
[Brief description of the drawings]
1 is a cross-sectional view showing a schematic structure of a main part of an injection molding machine according to the present invention. FIG. 2 is an enlarged cross-sectional view of the mold mechanism portion of FIG. FIG. 4 is an enlarged sectional view of the mold mechanism when the mold is closed. FIG. 4 is an enlarged sectional view of the mold mechanism shown in FIG. 1 and a resin is filled. FIG. 5 is a drawing of the mold mechanism shown in FIG. Fig. 6 is an enlarged cross-sectional view when the gate is cut. Fig. 6 is a drawing of the mold mechanism portion of Fig. 1 and an enlarged cross-sectional view when the core is compressed. Fig. 7 is a drawing of the die mechanism portion of Fig. 1 and when the die is opened. Enlarged cross-sectional view [Fig. 8] Fig. 1 is a drawing of the mold mechanism part, and is an enlarged cross-sectional view when the gate protrudes. [Fig. Description】
(A) ... Injection molding machine (a) ... Injection mechanism (b) ... Mold mechanism
(1) ... Mold
(2) ... Mold cavity
(3)… Resin
(4) ... Screw
(5)… Core mold
(6)… Core compression plate
(8)… Control device
(11) (12) (31) (40) ... Servo motor
(30)… Gate cut pin
(54)… Pressure sensor

Claims (4)

Core compression injection molding having a mold in which a core mold is disposed, and a mold mounting plate in which a core compression plate for pressing the core mold in a direction in which the filling resin is compressed is disposed. In the machine, an elastic body is disposed between the core compression plate and the mold mounting plate, and the core compression plate presses the mold in the closing direction via the elastic body. Core compression injection molding machine. A fixed mold and a movable mold in which the core mold is disposed, a fixed die plate for mounting the fixed mold, and a core compression plate for pressing the core mold in the direction of compressing the filling resin are arranged inside. In a core compression injection molding machine having a movable die plate to which a movable mold is attached, an elastic body is disposed between the core compression plate and the movable die plate, and the core compression plate is A core compression injection molding machine, wherein the movable mold is pressed in a closing direction through the elastic body . A fixed mold and a movable mold in which the core mold is disposed, a fixed die plate for mounting the fixed mold, and a core compression plate for pressing the core mold in the direction of compressing the filling resin are arranged inside. A movable die plate to which the movable mold is attached, an elastic body disposed between the core compression plate and the movable die plate, and the movable die plate is reciprocated through the elastic body. and possess a driving section for pressing the core mold directly, a core compression injection molding machine in which the core compression plate is characterized in that for pressing the movable die in the closing direction via the elastic body.   The core compression injection molding machine according to claim 1, wherein the elastic body is a compression coil spring.

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