JP2009255463A - Injection molding machine and injection molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine and an injection molding method which has both of merits of a hydraulic injection molding machine and an electromotive injection molding machine in the injection molding machine of performing the molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold. <P>SOLUTION: In the injection molding machine 11 of performing the molding by injecting the molten resin into the cavity 68 formed between the fixed mold 26 and the movable mold 32, a shift amount of a movable board 27 with respect to a fixed board 17 is determined by a first position detecting means 35a which detects a shift amount A of a mold opening and closing mechanism driven by a servo motor 35 and a second position detecting means 33 which detects a shift amount B of a mold-clamping cylinder 29 driven by a servo valve 47. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

Conventionally, as an injection molding machine for molding a disk substrate or the like, 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, an injection molding machine that performs molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold, and combines the advantages of a hydraulic injection molding machine and an electric injection molding machine. Another object is to provide an injection molding machine and an injection molding method. Another object of the present invention is to provide an injection molding machine and an injection molding method capable of accurately detecting the position of the movable platen relative to the fixed platen.

The injection molding machine according to the present invention is a shift of a mold opening / closing mechanism driven by a servo motor in an injection molding machine that performs molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold. The first position detecting means for detecting the amount and the second position detecting means for detecting the deviation amount of the clamping cylinder driven by the servo valve determine the deviation amount of the movable platen relative to the fixed platen. .

The injection molding method of the present invention is an injection molding method in which a molten resin is injected into a cavity formed between a fixed mold and a movable mold to perform molding. The shift amount of the movable platen relative to the fixed platen is obtained from the shift amount and the shift amount of the clamping cylinder driven by the servo valve.

An injection molding machine and an injection molding method according to the present invention include a mold opening / closing operation driven by a servo motor in an injection molding machine that performs molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold. Since the first position detecting means for detecting the deviation amount of the mechanism and the second position detecting means for detecting the deviation amount of the clamping cylinder driven by the servo valve, the deviation amount of the movable platen relative to the fixed platen is obtained. In addition to eliminating the problem of warping of the movable platen and reducing the time required to generate the desired mold clamping force, the position of the movable platen relative to the fixed platen can be accurately detected.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of a disk injection molding machine according to the present embodiment and shows 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 injection 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 injection molding machine according to the present embodiment. FIG. 4 is a diagram showing the shift amount of the movable platen relative to the fixed platen of the disk injection molding machine. FIG. 5 is a time chart showing the control of the mold opening / closing mechanism and the mold clamping mechanism.

As shown in FIGS. 1 to 3, the injection molding machine of the present invention is a vertical disk injection molding machine 11 in which an injection device 12 is provided in the upper portion and a mold clamping device 13 is provided in the lower portion. 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 disk injection molding machine 11, and four tie bars are provided between the fixed platen 17 and the pressure receiving platen 18 below the fixed platen 17. 19 is disposed. 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 opening / closing mechanism will be described first. As shown in FIGS. 1 and 2, the toggle link 21 of the mold opening / closing mechanism has one end attached to the second movable plate 28 and the other end attached to the second link 21b. The first 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 closer to the third link 21c, and one end attached to the second link 21b. The other end includes a third link 21c attached to the cross head 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 servo motor 35 is provided with an encoder 35a which is a first position detecting means for detecting the deviation A1 of the mold opening / closing mechanism such as the cross head 34, the toggle link 21 and the second movable plate 28. Yes. Therefore, the relative position of the second movable plate 28 with respect to the pressure receiving plate 18 can be detected by the encoder 35a.

Therefore, the deviation amount A1 of the second movable platen 28 with respect to the pressure receiving platen 18 is based on the detected value of the encoder 35a when the toggle link 21 is extended and the second movable platen 28 is raised as shown in FIG. Detected. As the first position detecting means, other position sensors such as a linear scale may be used instead of the encoder 35a. The origin A0 may be a position where the toggle link 21 is bent to the maximum or a mold opening completion position.

In the disk injection molding machine 11 of this 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.

Next, the mold clamping mechanism will be described. Although the mold clamping cylinder 29 is a return cylinder, the piston 30 has 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), which is a second position detecting means for detecting the shift amount B1 of the clamping cylinder 29, is disposed on one side surface of the first movable plate 27 and the second movable plate 28. Yes.

Therefore, the deviation amount B1 of the first movable plate 27 with respect to the second movable plate 28 is a position sensor when the ram 31 of the clamping cylinder 29 is most extended and the first movable plate 27 is raised most as shown in FIG. The detected value of 33 is detected as the origin B0. The origin B0 may be a position where the first movable platen 27 is at the lowest position. As the second position detecting means, an encoder type or a non-contact type sensor that detects a rotation angle may be used, and the type and number are not limited. Further, the distance between the fixed platen 17 and the first movable platen 27 may be measured by the second position detecting means, and the attachment position is not limited.

The diameter of the ram 31 of the clamping cylinder 29 is set 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 as pressure detection means is attached to the pipe line 48 to the mold opening side oil chamber 50, and a pressure sensor 53 as pressure detection means is also attached to the pipe line 49 to the mold clamping side oil chamber 51. Installed. 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. Further, the switching valve 46, the servo valve 47, the pressure control valve 56, the pressure sensors 52, 53, and the like are electrically connected to the control device 58 of the disk injection 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.

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 that is pivotally supported in the housing and fixed to 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, how to determine the amount of shift of the movable platen 20 (particularly the first movable platen 27) with respect to the fixed platen 17 of the disk injection molding machine 11 will be described with reference to FIG. As described above, the deviation amount A1 of the second movable plate 28 with respect to the pressure receiving plate 18 is obtained by setting the detected value of the encoder 35a in the state where the toggle link 21 is extended as shown in FIG. A deviation amount A1 from A0 is detected and obtained. Further, the deviation amount B1 of the first movable platen 27 is obtained by setting the detected value by the position sensor 33 in the state where the ram 31 of the mold clamping cylinder 29 is most extended as the origin B0 as shown in FIG. A deviation amount B1 from B0 is detected and obtained. Then, as shown in FIG. 4C, the distance between the lower surface of the fixed platen 17 and the upper surface of the first movable platen 27 when both the second movable platen 28 and the first movable platen 27 are at the origins A0 and B0. The system value C is set in the control device 58. From the above point, as described in FIG. 4A, the mold position absolute value D, which is the distance of the first movable platen 27 to the fixed platen 17, is calculated by the controller 58 as A1 + B1 + C. In FIGS. 4A and 4B, the distance between the first movable plate 27 and the second movable plate 28 is not changed. Therefore, A1 in FIG. 4A and A1 in FIG. 4B. Is equal to

Then, by subtracting the mold thickness E which is obtained by adding the mold thickness E1 of the fixed mold 26 and the mold thickness E2 of the movable mold 32 from the mold position absolute value D, the distance between molds F is controlled. 58. Therefore, in the present invention, the detected values of both the encoder 35a as the first position detecting means and the position sensor 33 as the second position detecting means are sent to the control device 58, and the deviation amount of the first movable platen 27 with respect to the fixed platen 17 is detected. Can be requested. Further, since the mold thickness E of the molding dies 26 and 32 is measured and inputted to the control device 58 when the molding dies 26 and 32 are attached in advance, the inter-mold distance F can be obtained. The above is expressed by mathematical formulas as follows.

Next, a disc substrate for Blu-ray Disc (registered trademark) using the disc injection molding machine 11 (diameter 120 mm, thickness 1.1 mm, track pitch 0.32 μm: all values are within the allowable molding error) The molding will be described with reference to FIG. 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. The position of the piston 30 and the ram 31 of the mold clamping cylinder 29 in the movable platen 20 is controlled to be the optimum position (deviation amount B) when the mold is opened during 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 deviation amount B 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. The 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. At this time, the position of the second movable plate 28 with respect to the pressure receiving plate 18 is detected as a deviation A1 as shown in FIG. When the encoder 35a detects that the toggle link 21 is extended to the set position and the deviation amount A1 becomes 0, the mold opening / closing servo motor 35 is stopped, the servo is locked (position holding), and the mold is closed. 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, the position of the first movable platen 27 with respect to the second movable platen 28 has already been controlled to be held by the clamping cylinder 29. Therefore, when the mold closing is completed, the fixed movable plate 32 is moved between the fixed mold 26 and the movable mold 32. A cavity 68 is formed. The mold clamping force at this time is a relatively low pressure of 10 to 100 kN as an example. When the mold closing is completed, the deviation A1 of the mold opening / closing mechanism is zero. Further, the shift amount B1 of the mold clamping mechanism is a positive number (depending on the mold thickness, for example, about 10 mm). Therefore, in the control device 58, the mold position absolute value D which is the distance of the first movable platen 27 to the fixed platen 17 is calculated by adding the system value C to the deviation amount B1. Then, the inter-mold distance F is calculated by subtracting the mold thickness E from the mold position absolute value D. In the disk injection molding machine 11, the distance F between molds when the mold closing is completed and the parting surfaces come into contact with each other is displayed on the display screen as 0 mm.

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 and the deviation amount B1 is slightly increased. However, the backward movement of the movable mold 32 and the like is almost absorbed by the stroke of the clamping cylinder 29. Therefore, since the toggle link 21 remains in the set extended state, the positional relationship (deviation A1) between the second movable plate 28 and the pressure receiving plate 18 hardly changes, and a large load is applied to the servo motor 35. There is no.

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, the value of the pressure sensor 53 of the clamping cylinder 29 (or the pressure difference between the pressure sensor 53 and the pressure sensor 52) is set to a predetermined set value of 16 to 19 MPa in 0.03 to 0.07 seconds. The pressure can be increased until 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 compression control can be directly performed on the molten resin in the cavity 68 by the ram 31, the first movable platen 27 is not warped, 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). Further, at this time, the distance F between the molds displayed on the screen of the fixed mold 26 and the movable mold 32 is the ram of the mold clamping cylinder 29 when the mold clamping force is generated and the tie bar 19 is extended. Since 31 and the first movable platen 27 are moved forward, a negative number (for example, −0.1 to −0.5 mm) is obtained.

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. In the depressurization, the mold clamping cylinder 29 is pressure-controlled to lower the minimum mold clamping pressure at which the movable platen 20 is not lowered by its own weight. 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 driving the mold opening / closing servo motor 35 to perform mold opening. Therefore, since the toggle link 21 is operated in a state where almost no mold clamping force is generated, a large load is not applied to the link. At this time, variable control of the pressure reducing time of the clamping cylinder 29 and variable control of acceleration time or acceleration up to a predetermined speed when the movable mold 32 is moved backward by the servo motor 35 are made possible. This makes it possible to correct the tilt and release moire of the disk substrate to be molded. Then, the molded disk substrate is taken out to the movable mold 32 side.

Then, the movable platen 20 and the like are moved toward the mold opening completion position by the servo motor 35 of the mold opening / closing mechanism. At the same time as the ram 31 of the mold clamping cylinder 29 is simultaneously controlled by the position control during the mold opening. It will be returned to the position. When the movable platen 20 or the like reaches the mold opening completion position due to the bending of the toggle link 21, the servo is locked and the position of the movable platen 20 is maintained. Thereafter, the disk substrate is ejected from the movable mold 32 by the ejector sleeve and the projecting pin at the mold opening completion position, and is taken out by a take-out robot (not shown). Therefore, the disk substrate can be always taken out at a stable take-out 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 disk injection molding machine 11 is advantageous for molding a uniform disk substrate without the influence of gravity due to the installation area and the molten resin in the cavity 68, but a movable plate and a movable mold are horizontally arranged. The present invention may be used in a moving horizontal disk forming machine. In this embodiment, the vertical disk injection molding machine provided with an injection device facing downward has been described. However, the injection device is oriented in such a manner that the heating cylinder is provided in the horizontal direction and the nozzle is bent in a right angle direction. It may be provided 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. The mold clamping cylinder of the mold clamping means may be arranged in a single movable platen to operate a block in the movable mold. In that case, the shift amount of the block is detected by the second position detecting means. The mold clamping cylinder may be a double rod type.

In the present 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 a molded product such as another disk substrate, an optical product, and a thin plate suitable for compression molding. 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 injection press is particularly preferably used for molding a thin disk substrate for DVD, a light guide plate, and the like. In injection press molding, since the movable mold is advanced from the stop position, in the case of only a normal toggle link mechanism, it is necessary to extend the toggle link from a bent state, and a large load is applied to the servo motor. However, in the present invention, the mold clamping cylinder is advanced from the state where the toggle link is extended, so that the load on the servo motor is small. In addition, the relationship between injection and mold clamping side compression control includes various timings such as starting compression of the movable mold simultaneously with injection, starting compression control during injection, and starting compression control after injection. included.

It is a front view of the injection molding machine for disks of this embodiment, and is a figure showing the state at the time of mold opening. It is a front view of the injection molding machine for disks of this embodiment, and is a figure showing the state at the time of a mold closing. It is an expanded sectional view of the principal part of the injection molding machine for disks of this embodiment. It is a figure which shows the deviation | shift amount of the movable plate | board with respect to the fixed plate | board of the injection molding machine for disks. It is a time chart which shows control of a mold opening / closing mechanism and a mold clamping mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Injection molding machine for disks 13 Clamping device 17 Fixed platen 20 Movable platen 21 Toggle link 26 Fixed mold 27 First movable plate 28 Second movable plate 29 Clamping cylinder 31 Ram 32 Movable die 35 Servo motor for mold opening / closing A0 , B0 Origin A1 Deviation amount of the second movable platen B1 Deviation amount of the first movable platen C System value D Mold position absolute value E, E1, E2 Mold thickness F Distance between molds

Claims (6)

In an injection molding machine that performs molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold,
First position detecting means for detecting a shift amount of a mold opening / closing mechanism driven by a servo motor;
An injection molding machine characterized in that a shift amount of a movable platen relative to a fixed platen is obtained by second position detecting means for detecting a shift amount of a clamping cylinder driven by a servo valve. 2. The injection molding machine according to claim 1, wherein the mold clamping cylinder is provided with pressure detection means, and compression control of the molten resin in the cavity is performed during mold clamping. The injection molding machine according to claim 1 or 2, wherein the movable plate is moved up and down with respect to the fixed plate to open and close the mold. In an injection molding method of performing molding by injecting molten resin into a cavity formed between a fixed mold and a movable mold,
An injection molding method characterized in that a shift amount of a movable plate relative to a fixed platen is obtained from a shift amount of a mold opening / closing mechanism driven by a servo motor and a shift amount of a mold clamping cylinder driven by a servo valve. 5. The injection molding method according to claim 4, wherein the mold clamping cylinder is provided with pressure detection means, and compression control of the molten resin in the cavity is performed during mold clamping. The injection molding method according to claim 4 or 5, wherein the movable plate is moved up and down with respect to the fixed plate to open and close the mold.

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