JP5093809B2 - Disc substrate molding machine and disc substrate molding method - Google Patents

Description

The present invention relates to a disk substrate molding machine and a disk substrate molding method for molding a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold.

Conventionally, as a disk substrate molding machine, those described in Patent Documents 1 to 4 are known. In Patent Document 1, mold opening / closing and clamping are performed by a hydraulic clamping cylinder. However, Patent Document 1 has a problem in terms of energy saving in addition to a large amount of hydraulic oil. In order to deal with the above problem, Patent Document 2 performs mold opening / closing and mold clamping by a combination of a servo motor and a toggle link mechanism. However, Patent Document 2 has a problem in that since the links are attached in the vicinity of both ends of the rear surface of the movable platen, the center of the movable platen cannot be pressed, and good transfer cannot be performed due to the bending of the movable platen. Further, in Patent Document 2, the combination of the servo motor and the toggle link mechanism has a problem that it takes time until a desired mold clamping force is generated by mold clamping after the mold is closed. Further, in Patent Document 2, since the mold is clamped by a toggle link, there is a problem that when the distance between the movable platen and the pressure receiving plate is changed, the mold clamping force is changed and it is difficult to cope with the thermal expansion of the molding die. Further, Patent Document 3 uses a hydraulic toggle link mechanism and a servo motor mold clamping mechanism. However, the position control by the hydraulic toggle link mechanism cannot be performed with high accuracy, and it is desired to perform mold clamping from the mold closed state. As in Patent Document 2, there is a problem that it takes time until the mold clamping force is generated.

Patent Documents 1 to 3 are so-called horizontal injection molding machines in which the movable platen and the movable mold move in the horizontal direction. Since the cavity is formed in the vertical direction, the vertical direction in the cavity is affected by the influence of gravity. However, there is a problem that it is difficult to form a uniform disk substrate. In order to solve the above problem, the one described in Patent Document 4 is known. Patent Document 4 discloses a vertical disk injection molding machine that solves the problem that the molding of a horizontal injection molding machine is affected by gravity. However, also in the types of FIGS. 1 and 2 of Patent Document 4, the movable die plate 5 is bent, so that the problem that the center of the movable mold cannot be pressed has not been solved. In addition, the problem that it takes time until the desired mold clamping force is generated by mold clamping from the mold closed state due to the combination of the servo motor and toggle link, and the problem at the time of thermal expansion of the molding die have not been solved. The best transfer could not be performed on the disc substrate. Furthermore, the toggle type molding machine has a complicated mold thickness adjustment mechanism that moves the pressure plate so that a predetermined clamping force can be obtained even when the mold is changed. It was necessary to adjust the position of the pressure plate.

JP-A-8-276479 (0028, 0029, FIG. 2) Japanese Patent Laying-Open No. 2003-77178 (0017, FIG. 2) JP-A-6-87142 (0057, FIG. 6) Japanese Patent Laying-Open No. 2005-28634 (0009, FIGS. 1 and 2)

Therefore, in the present invention, in a disk substrate molding machine that molds a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold, a hydraulic disk substrate molding machine and an electric disk substrate molding It is an object of the present invention to provide a disk substrate molding machine and a disk substrate molding method having the advantages of the machine. In addition, in the case where the disk substrate molding machine of the present invention is a vertical type, a disk substrate molding machine and a disk substrate molding method capable of molding a uniform disk substrate in a cavity without being affected by gravity are provided. With the goal.

The disk substrate molding machine of the present invention is a disk substrate molding machine that molds a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold, and is a mold opening / closing driven by a servo motor. And a mold clamping mechanism having a mold clamping cylinder driven by a servo valve, the movable mold is disposed on the first movable platen, and a toggle link constituting the mold opening / closing mechanism is attached to the back surface. The mold clamping cylinder is disposed on the second movable platen, the ram of the mold clamping cylinder is fixed to the back surface of the first movable platen, an accumulator is connected to the mold clamping cylinder, and the oil accumulated in the accumulator The pressure of the mold clamping cylinder is increased by the pressure to pressurize the molten resin in the cavity .

The disk substrate molding method of the present invention is a disk substrate molding method for molding a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold, and a mold driven by a servo motor. An opening / closing mechanism and a mold clamping mechanism having a mold clamping cylinder driven by a servo valve are provided. The movable mold is disposed on the first movable platen, and a toggle link constituting the mold opening / closing mechanism is attached to the back surface. The clamping cylinder is disposed on the second movable plate, the ram of the clamping cylinder is fixed to the back surface of the first movable plate, and the diameter of the ram is larger than the diameter of the disk to be molded, wherein the type accumulator is connected to the clamping cylinder, it performs boosting of the mold clamping cylinder by the accumulator oils in the accumulator to pressurize the molten resin in the cavity To.

A disk substrate molding machine and a disk substrate molding method according to the present invention include a servo motor in a disk substrate molding machine that molds a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold. A toggle link which is provided with a mold opening / closing mechanism to be driven and a mold clamping mechanism having a mold clamping cylinder driven by a servo valve, and the movable mold is disposed on the first movable platen. The mold clamping cylinder is disposed on a second movable plate attached to the back surface, a ram of the mold clamping cylinder is fixed to the back surface of the first movable plate, an accumulator is connected to the mold clamping cylinder, and the accumulator to the accumulator oils performs boosting of the clamping cylinder, so pressurizing the molten resin in the cavity, as well as eliminate the movable platen warpage problems, desired By shortening the time until the clamping force is generated, it is possible to perform a good transfer molded disc substrate to be molded. Further, energy saving can be achieved as compared with a conventional hydraulic cylinder clamping cylinder that opens and closes and molds.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of a disk substrate molding machine according to the present embodiment, showing a state when the mold is opened. FIG. 1 shows a state where the injection device is also raised. FIG. 2 is a front view of the disk substrate molding machine according to the present embodiment, and shows a state when the mold is closed. FIG. 3 is an enlarged cross-sectional view of a main part of the disk substrate molding machine according to the present embodiment.

As shown in FIGS. 1 to 3, the disk substrate molding machine is a vertical disk substrate molding machine 11 in which an injection device 12 is provided in the upper part and a mold clamping device 13 is provided in the lower part. Four frame members 15 are erected on the base 14, and a fixed platen 17 is fixed to the frame members 15 via beam members 16 provided in the horizontal direction. The fixed platen 17 is disposed at an intermediate height in the entire vertical disk substrate molding machine 11, and four fixed plates 17 are provided between the fixed platen 17 and the pressure receiving plate 18 below the fixed platen 17. A tie bar 19 is provided. A movable plate 20 is attached to the tie bar 19 so as to be movable up and down with respect to the fixed plate 17. Further, a toggle link 21 of a mold opening / closing mechanism driven by a servo motor 35 is provided between the movable platen 20 and the pressure receiving plate 18. In addition to the mold opening / closing mechanism, a mold clamping cylinder 29 of the mold clamping mechanism is disposed inside the movable platen 20.

A mortar-like hole 24 into which the heating cylinder 22 and nozzle 23 of the injection device 12 are inserted is provided on the upper surface of the fixed platen 17, and two shift cylinders 25 for raising and lowering the injection device 12 are provided around it. On the other hand, a fixed mold 26 is fixed to the lower surface of the fixed platen 17. The movable platen 20 is composed of two movable plates 20, an upper first movable platen 27 and a lower second movable platen 28, and both movable plates 27, 28 are inserted into the tie bar 19 near the four corners. A movable mold 32 is attached to the central portion of the upper surface of the first movable platen 27, and a toggle link 21 is attached to the central portion of the rear surface (lower surface central portion) of the second movable platen 28. A tightening cylinder 29 is provided.

The mold clamping mechanism will be described. Although the mold clamping cylinder 29 is a return cylinder, the piston 30 is provided with a pressure receiving area on the mold clamping side larger than a pressure receiving area on the mold opening side. The other end of the ram 31 fixed to the piston 30 is fixed to the back surface (lower surface) of the first movable platen 27. A position sensor 33 (MTS sensor) for measuring the distance between the first movable platen 27 and the second movable platen 28 is disposed on one side surface of the first movable platen 27 and the second movable platen 28.

The diameter of the ram 31 is larger than the diameter of the disk substrate to be molded and the stamper 64 of the movable mold 32. Further, the stroke of the ram 31 is about 10 to 30 mm because it is the amount of movement at the time of mold clamping and the mold thickness adjustment at the time of mold change, and it requires a very small amount of oil compared to the conventional hydraulic mold clamping mechanism. Can be operated. Further, although not shown in the drawings, the first movable plate 27 and the ram 31 are provided with a hydraulic cylinder and an air cylinder for operating a male cutter, a projecting pin, an ejector sleeve, and a pipe line thereof. The male cutter, the projecting pin, the ejector sleeve, and the shift cylinder 25 described above may all be moved forward and backward by a servo motor and a ball screw mechanism.

The hydraulic circuit of the mold clamping cylinder 29 will be described. As shown in FIG. 3, a pump 41 that is operated by a motor is provided, and a conduit 42 through which oil is sent from the pump 41 is connected to a cartridge valve via a check valve 43. 44. A pilot line 45 for operating the cartridge valve 44 is provided in the pipe line 42 on the way to the cartridge valve 44, and a switching valve 46 is provided in the pilot line 45. A servo valve 47 is disposed at the tip of the cartridge valve 44. The A port and the B port of the servo valve 47 are connected to the mold opening side oil chamber 50 of the clamping cylinder 29 via the pipe line 48, the pipe line 49, and the like. The mold clamping side oil chamber 51 is connected. A pressure sensor 52 is attached to the pipe line 48 to the mold opening side oil chamber 50, and a pressure sensor 53 is attached to the pipe line 49 to the mold clamping side oil chamber 51. Further, an accumulator 55 is connected to a pipeline 54 branched from the pipeline 42 to the cartridge valve 44. A pipe line 42 between the pump 41 and the check valve 43 is connected to a pressure control valve 56. The pump 41, the servo valve 47, the pressure control valve 56, and the like are connected to the hydraulic tank 57. The switching valve 46, the servo valve 47, the pressure control valve 56, the pressure sensors 52, 53, etc. are electrically connected to the control device 58 of the vertical disk substrate molding machine 11, respectively. The control device 58 is also electrically connected to the main body and encoder of the mold opening / closing servomotor 35, the injection servomotor 75, and the metering servomotor 78 via a servo amplifier or the like. Further, the position sensor 33 is also electrically connected.

The mold opening / closing mechanism will be described. As shown in FIGS. 1 and 2, the toggle link 21 of the mold opening / closing mechanism is a first one in which one end is attached to the second movable plate 28 and the other end is attached to the second link 21b. The link 21a has one end attached to the pressure receiving plate 18, the other end attached to the first link 21a and the other end attached to the third link 21c, one end attached to the second link 21b, and the like. The end consists of a third link 21c attached to the crosshead 34. A mold opening / closing servomotor 35 of a mold opening / closing mechanism is attached to the side of the pressure receiving plate 18 by a bracket. A ball screw 36 is attached to the pressure receiving plate 18 via a bearing (not shown) so as to be rotatable in the vertical direction. A pulley 37 is attached to the lower end of the ball screw 36 in the horizontal direction, and a timing belt 39 is disposed between the lower end of the ball screw 36 and the drive pulley 38 of the mold opening / closing servomotor 35. A ball screw nut 40 fixed to the cross head 34 is disposed above the ball screw 36, and the ball screw nut 40 and the cross head 34 are moved up and down by the rotation of the ball screw 36. The mold opening / closing servomotor 35 is provided with an encoder 35 a for detecting the position of the second movable plate 28 with respect to the pressure receiving plate 18.

In the vertical disk substrate molding machine 11 of the present embodiment, the mold opening / closing is performed by a combination of the mold opening / closing servo motor 35 and the toggle link 21 and the mold clamping is performed by the mold clamping cylinder 29. The link 21 can be reduced in size. Further, in this embodiment, even if the thickness of the molding die is changed, it can be dealt with by adjusting the stroke position of the clamping cylinder 29. Therefore, the mold thickness adjusting mechanism for moving the position of the pressure receiving plate 18 is not attached.

As shown in FIG. 3, the fixed mold 26 includes a sprue bush 61 through which the molten resin injected upon contact with the nozzle 23 passes, a gate insert block 62, a fixed mirror plate 63, and the like. The gate insert block 62 is formed with a mescutter. The movable mold 32 includes a projecting pin, a male cutter, an ejector sleeve (not shown), an inner peripheral stamper holder 65 that presses the inner peripheral side of the stamper 64, an outer peripheral stamper holder 66 that presses the outer peripheral side of the stamper 64, a movable mirror plate 67, and the like. I have. When the mold is closed, the outer peripheral surface of the fixed mirror plate 63 is fitted into the inner hole of the outer peripheral stamper holder 66 to form a variable volume cavity 68. The disk substrate molding die is not limited to the above-mentioned one, and may be one in which a stamper is disposed on a fixed die, and a side wall forming portion that is advanced and retracted by a spring to form a disk substrate is provided on one mold. It may be attached and the front surface of the side wall forming portion may be in contact with the other mold to form a cavity.

As shown in FIGS. 1 and 2, a guide member 71 that guides the vertical movement of the injection device 12 is attached to one of the two beam members 16 of the four frame members 15. The upper side of the guide member 71 is pivotable with respect to the frame member 15 by a shaft 72. A housing plate 73 and a pusher plate 74 are attached to the guide member 71 so as to be slidable in the vertical direction. The heating cylinder 22 is fixed downward on the lower surface of the housing plate 73, and the rods of the shift cylinder 25 are attached thereto. In addition, injection servomotors 75 are respectively attached to the protruding portions that extend horizontally on both sides of the housing plate 73. A ball screw 76 is directly connected to a rotor (not shown) of the servo motor 75 for injection, and the ball screw 76 is rotatably supported by a ball screw nut 77 which is pivotally supported in the housing and fixed on the pusher plate 74 on the upper side. . The rear end of a screw (not shown) disposed in the heating cylinder 22 is connected to a screw sleeve, and the screw sleeve is directly connected to the rotor of the measuring servo motor 78. In addition, an opening 79 through which a resin material is introduced into the heating cylinder 22 is formed on the other surface of the housing plate 73, and is connected to a resin reservoir (not shown) via a supply device 80 provided with a feed screw. Therefore, in the injection device 12, the pusher plate 74 moves up and down with respect to the housing plate 73 by the operation of the injection servo motor 75, and the screw sleeve and the screw move forward and backward accordingly. The screw is rotated through the screw sleeve by the operation of the measuring servo motor 78.

Next, a disc substrate for Blu-ray Disc (registered trademark) using the vertical disc substrate molding machine 11 (diameter 120 mm, thickness 1.1 mm, track pitch 0.32 μm: all values are within allowable molding errors. ) Will be described. In this embodiment, which is a field of injection molding, disk substrate molding is performed by injection compression molding in which the movable mold 32 is slightly retracted by the injection pressure at the time of injection and then compressed. First, the position of the piston 30 and the ram 31 of the mold clamping cylinder 29 in the movable platen 20 is controlled so as to be the optimum position (deviation amount B) during mold opening / closing or mold opening in the previous molding cycle. The position control of the piston 30 and the ram 31 of the mold clamping cylinder 29 is closed loop control by detecting the position of the first movable plate 27 with respect to the second movable plate 28 by the position sensor 33 and controlling the servo valve 47. At this time, the pressures in both the mold opening side oil chamber 50 and the mold clamping side oil chamber 51 are equal to or higher than a certain pressure. In addition, the oil sent from the pump 41 is accumulated in the accumulator 55 during the cooling process or after the oil is sealed in the clamping cylinder 29.

Next, when a mold closing signal is transmitted from the control device 58 and the mold opening / closing servomotor 35 of the mold opening / closing mechanism is actuated to rotate the ball screw 36, the toggle link 21 is moved together with the rise of the ball screw nut 40 and the crosshead 34. It is stretched. When the encoder 35a detects that the toggle link 21 has been extended to the set position, the mold opening / closing servomotor 35 is stopped and servo-locked (position maintained), and the mold closing is completed. The state of the toggle link 21 at the mold closing completion position is a state immediately before the toggle link 21 is completely extended in a straight line and the toggle link 21 is bent slightly inward. As described above, since the position of the first movable plate 27 with respect to the second movable plate 28 has already been controlled by the clamping cylinder 29, the cavity between the fixed mold 26 and the movable mold 32 is completed when the mold is closed. 68 is formed. The mold clamping force at this time is a relatively low pressure of 10 to 100 kN as an example.

Then, a polycarbonate molten resin having a nozzle temperature of 340 to 380 ° C., an injection speed of 100 to 400 mm / sec, and an injection pressure of 10 to 60 MPa is injected from the nozzle 23 of the injection device 12 that always touches the fixed mold 26 since the previous molding. Injection into the cavity 68. At this time, the movable mold 32 is held at the mold closing completion position, but is slightly retracted by the injection pressure. However, the backward movement of the movable mold 32 and the like is almost absorbed by the stroke of the clamping cylinder 29. Accordingly, since the toggle link 21 remains in the set extended state, the positional relationship between the first movable plate 27 and the pressure receiving plate 18 hardly changes, and a large load is not applied to the servo motor 35.

Next, when it is detected that the screw of the injection device 12 has advanced to a predetermined position slightly after the start of injection, a signal is sent from the control device 58 to the switching valve 46, the cartridge valve 44 is opened, and the accumulator is opened. The oil accumulated in 55 and the oil from the pump 41 are sent to the mold clamping side oil chamber 51 of the mold clamping cylinder 29 through the servo valve 47. Then, the oil in the mold opening side oil chamber 50 is dropped into the drain through the servo valve 47. At this time, by using the accumulator 55, it is possible to increase the pressure until the value of the pressure sensor 53 of the mold clamping cylinder 29 reaches a predetermined set value of 16 to 19 MPa in 0.03 to 0.07 seconds. Therefore, the ram 31 of the mold clamping cylinder 29 overcomes the injection pressure and is advanced at a high speed. At the same time, the mirror plate 67 of the movable mold 32 is advanced to the position indicated by the one-dot chain line in FIG. Therefore, the molten resin in the cavity 68 can be rapidly compressed and extended to achieve good transfer molding. Further, since the ram 31 can directly pressurize the molten resin in the cavity 68, the first movable plate 27 does not warp, and the best shape can be obtained by selecting the shape and cross-sectional area of the ram 31. The pressing area can be selected. In this embodiment, since the molten resin is extended in the cavity 68 formed in the horizontal direction, a non-uniform disk is not formed due to the influence of gravity.

When the pressure sensor 53 (or the differential pressure between the pressure sensors 52 and 53) detects that the pressure in the mold clamping cylinder 29 has reached the predetermined set value, the differential pressure between the pressure sensors 52 and 53 is detected thereafter. Then, compression control (multistage pressure feedback control) for closed-loop control of the servo valve 47 is performed. At this time, the maximum value of the mold clamping force generated by the mold clamping cylinder 29 is 300 to 700 kN, and the surface pressure with respect to the molten resin is about 26 MPa to 62 MPa. At this time, the ram 31 is advanced in a manner that overcomes the radiant power, whereby the clamping force is increased. As a result, the tie bar 19 is extended and the pressure receiving plate 18 is slightly lowered (retracted).

In order to increase the mold clamping pressure rapidly during injection compression control as described above, the pressure is increased by the mold clamping cylinder 29 controlled by the servo valve 47, rather than by a mold clamping mechanism using only a toggle link and a servo motor. By performing the above, a desired mold clamping force or cavity internal pressure can be obtained in a shorter time. As a result, good transfer molding can be performed in the cavity 68, which is desirable for a disk substrate. And the compression in the cavity 68 performs pressure holding on the injection device 12 side. Further, during pressure holding, the male cutter of the movable mold 32 moves forward to perform gate cutting. When the cooling time of the molten resin in the cavity 68 ends, the clamping cylinder 29 is depressurized. Around that time, release air is ejected from the fixed mold 26 and the movable mold 32. Then, the toggle link 21 is actuated by the mold opening / closing servo motor 35 to open the mold. The molded disk substrate is taken out to the movable mold 32 side, and then further ejected by an ejector sleeve and a projecting pin, and is ejected by a take-out robot (not shown). As described above, the ram 31 of the clamping cylinder 29 is returned to a predetermined position.

The present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be applied to those modified by a person skilled in the art based on the gist of the present invention. The vertical disk substrate molding machine 11 is advantageous in forming a uniform disk substrate without the influence of gravity due to the installation area and the molten resin in the cavity 68, but the movable plate and movable mold in the horizontal direction. The present invention may be used in a horizontal disc forming machine in which the In this embodiment, a vertical disk substrate molding machine provided with an injection device facing downward has been described. However, the direction of the injection device is such that a heating cylinder is provided in a horizontal direction and a nozzle is bent in a right angle direction and is downward. Or a nozzle provided in the horizontal direction and guided to the cavity in the mold. Furthermore, an injection device may be provided below and a mold clamping device may be provided above.

The mold opening / closing mechanism driven by the servo motor is another type such as a combination of a ball screw and ball nut that opens and closes without using a toggle link, a crank mechanism, and a linear linear mechanism. May be.

In this embodiment, the formation of a disk substrate for a Blu-ray disc has been described. However, the present invention can also be used for forming other disk substrates. Then, a cavity is formed with the gap between the fixed mold and the movable mold slightly wider than the thickness of the disk substrate that is molded when the mold is closed with a toggle link, and the mold is moved by the mold clamping cylinder after the molten resin is injected. An injection press which is a field of injection compression molding in which a mold is advanced to compress molten resin in a cavity can also be used in the present invention. The molding by the injection press is particularly preferably used for molding a disk substrate such as a DVD having a small thickness. In injection press molding, the movable mold is rapidly advanced from the stop position. Therefore, in the case of only a normal toggle link mechanism, a large load is applied to the servo motor to extend the toggle link from a bent state. However, in the present invention, since the toggle link advances the mold clamping cylinder from the already extended state, the load on the servo motor is small. The relationship between injection and compression on the mold clamping side has various timings such as the one that starts compression control of the movable mold simultaneously with the injection, the one that starts compression control during injection, and the one that starts compression control after injection. Is included.

It is a front view of the disk substrate molding machine of this embodiment, and is a figure showing a state at the time of mold opening. It is a front view of the disk substrate molding machine of this embodiment, and is a view showing a state when the mold is closed. It is an expanded sectional view of the important section of the disc substrate molding machine of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Vertical disk board | substrate molding machine 13 Clamping apparatus 17 Fixed board 20 Movable board 21 Toggle link 26 Fixed mold 27 First movable board 28 Second movable board 29 Clamping cylinder 31 Ram 32 Movable mold 35 Servo motor for mold opening / closing

Claims (3)

In a disk substrate molding machine that molds a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold,
A mold opening / closing mechanism driven by a servo motor;
A mold clamping mechanism including a mold clamping cylinder driven by a servo valve;
The movable mold is disposed on the first movable platen,
The mold clamping cylinder is disposed on a second movable plate to which a toggle link constituting a mold opening / closing mechanism is attached to the back surface, and the ram of the mold clamping cylinder is fixed to the back surface of the first movable plate,
An accumulator is connected to the mold clamping cylinder, and the pressure of the mold clamping cylinder is increased by oil accumulated in the accumulator so as to pressurize the molten resin in the cavity . 2. The disk substrate molding machine according to claim 1, wherein a diameter of the ram is larger than a diameter of a disk to be molded. In a disk substrate molding method for molding a disk substrate by injecting molten resin into a cavity formed between a fixed mold and a movable mold,
A mold opening / closing mechanism driven by a servo motor;
A mold clamping mechanism including a mold clamping cylinder driven by a servo valve;
The movable mold is disposed on the first movable platen,
The mold clamping cylinder is disposed on a second movable plate to which a toggle link constituting a mold opening / closing mechanism is attached to the back surface, and the ram of the mold clamping cylinder is fixed to the back surface of the first movable plate,
The diameter of the ram is larger than the diameter of the disk to be molded. An accumulator is connected to the mold clamping cylinder, and the mold clamping cylinder is pressurized with oil accumulated in the accumulator to add molten resin in the cavity. A method for forming a disk substrate, comprising pressing.

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