JP2007090660A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine which can manufacture a precision optical component excellent in surface separation eccentricity by preventing the dislocation of a fixed mold by the falling or deflection of a fixed platen. <P>SOLUTION: The injection molding machine is equipped with the fixed mold 7, a movable mold 8 installed to be attached/separated to/from the fixed mold 7, and an injection unit 11 which is installed on the opposite mold-mating face side of the fixed mold 7 and supplies a molten resin into a cavity formed between the molds 7 and 8, can simultaneously form a plurality of the optical components each having an outside diameter of 12 mm or below and a surface roughness Ra of 20 nm or below, and has a motor driving device 43 which moves the movable mold 8 in relation to the fixed mold 7, a motor driving device 41 which makes the injection unit 11 be attached/separated to/from the fixed mold 7, and a controller 45 which prohibits the contact of the injection unit 11 with the fixed mold 7 by the motor driving device 41 while the fixed mold 7 and the movable mold 8 are not clamped. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an injection molding apparatus that molds an optical component using a mold. More specifically, the present invention relates to an injection molding apparatus that prevents the fixed platen from being bent and improves the molding accuracy.

  Conventionally, various molded products have been manufactured by injection molding using a mold. For example, Patent Document 1 discloses an injection molding machine for molding a disk for an information recording medium. The molding machine described in this document is generally configured as shown in FIG. That is, this molding machine has a fixed platen 101 and a cylinder 103, and four tie bars 104 are installed between them. A movable platen 105 is slidably supported on the tie bar 104. The movable platen 105 is driven by a cylinder 103. A fixed mold 107 and a movable mold 108 are attached to the fixed platen 101 and the movable platen 105, respectively. Then, with the movable mold 108 clamped to the fixed mold 107 by the cylinder 103, a resin material is supplied from the injection unit 111 to mold the disk.

  At the time of injection molding by such an injection molding apparatus, the injection unit 111 is brought into pressure contact with the fixed platen 101 at a predetermined pressure. Therefore, conventionally, the injection unit 111 is provided with drive means for moving forward and backward in the left-right direction in FIG. For example, Patent Document 2 discloses an injection unit including a hydraulic cylinder as a driving unit. In addition to this, there is a ball screw as a driving means of the injection unit. In addition, instead of advancing and retracting the injection unit, there is also a type in which a fixed platen is pressed against the injection unit side by a hydraulic cylinder. In any case, particularly in a micro molding machine having a clamping force of 150 kN or less, improvement in molding accuracy and downsizing of the apparatus are required.

In the case of continuous molding using an injection molding apparatus, the injection unit 111 is generally kept pressed against the fixed platen 101. Then, the movable platen 105 is driven and the mold is clamped to inject resin, and after cooling, the mold is opened and the molded product is taken out. Then, the movable platen 105 is driven again and the mold clamping is repeated. That is, the movable mold 108 is opened and closed with respect to the fixed mold 107 while applying the nozzle touch pressure that presses the injection unit 111 against the fixed platen 101.
Japanese Patent Laid-Open No. 10-323872 JP-A-8-11175 (FIG. 5)

  However, the above-described conventional injection molding apparatus has a problem that the deflection of the fixed platen 101 occurs when the mold is opened. For example, in the type in which the injection unit 111 is pressed against the fixed platen 101 with a ball screw or the like, the upper part of the fixed platen 101 may be bent toward the movable platen 105 when the mold is opened, as indicated by a broken line in FIG. When the mold is clamped for the next molding in the bent state as described above, there is a problem that the movable platen 105 and the movable mold 108 are misaligned as shown in FIG. Of course, these drawings show exaggerated deflection and misalignment.

  Alternatively, in the type in which the fixed platen 101 is pulled to the injection unit 111 side by a hydraulic cylinder or the like, the fixed platen 101 in the vicinity where the hydraulic cylinder is attached may bend to the injection unit 111 side as shown in FIG. When the mold is clamped for the next molding in such a bent state, the movable platen 105 and the movable mold 108 are misaligned as shown in FIG. These FIGS. 5 and 6 show a state seen from above in FIG. Of course, these figures also exaggerate the deflection and misalignment.

  If the next molding is performed in a state where the fixed platen 101 is bent as described above, the fixed platen 101 and the movable platen 105 may be misaligned particularly when the mold is touched or when the mold is clamped. There was a problem that it also caused the life of the mold to be shortened. On the other hand, a device for increasing the mechanical rigidity by increasing the thickness of the fixed platen 101 or holding the fixed platen 101 at the center has been devised, but there is a problem that the apparatus becomes larger. In particular, in micro-molding machines, the accuracy of eccentricity by surface is particularly strict, and there has been a demand for an injection molding apparatus that can achieve downsizing while maintaining mechanical rigidity and can continuously mold high-precision optical components.

  The present invention has been made to solve the problems of the conventional injection molding apparatus. That is, the problem is to provide an injection molding apparatus that can prevent the displacement of the fixed mold due to the falling or deflection of the fixed platen and can produce a high-precision optical component having excellent surface-specific eccentricity. is there.

  The injection molding apparatus of the present invention, which has been made for the purpose of solving this problem, includes a fixed mold, a movable mold provided so as to be able to contact with and separate from the fixed mold, and a reaction between the fixed mold and the fixed mold. An injection unit that is provided on the mold matching surface side and has an injection unit that supplies molten resin to the gap between both molds, and simultaneously forms a plurality of optical components having an outer diameter of 12 mm or less and a surface roughness Ra of 20 nm or less. A molding apparatus, a mold clamping drive unit that moves and clamps a movable mold relative to a fixed mold, a contact / separation drive unit that contacts and separates an injection unit from a fixed mold, and a fixed It has a prohibition part for prohibiting the contact of the injection unit to the fixed side mold by the contact / separation drive part when the side mold and the movable side mold are not clamped.

  According to the injection molding apparatus of the present invention, the movable side mold is brought into contact with the fixed side mold, and the molten resin is supplied into the gap therebetween, thereby molding the optical component. Here, since the prohibition part is provided, the contact of the injection unit with the fixed mold in the state where the fixed mold and the movable mold are not clamped is prohibited. That is, when the injection unit is brought into contact with the fixed mold, the fixed mold is firmly held together with the movable mold. Therefore, even if the injection unit is pressed, the fixed mold is not displaced. As a result, it is possible to prevent the displacement of the stationary mold due to the tilting and bending of the stationary platen, and the injection molding apparatus capable of producing a high-precision optical component having excellent surface-specific eccentricity.

The present invention further includes an input unit that accepts a user operation related to driving of the injection unit by the contact / separation driving unit, and the prohibiting unit is configured so that the user can operate the user when the fixed mold and the movable mold are not clamped. Regardless of the operation of the input unit by the, it is desirable to prohibit the operation of the contact / separation drive unit to bring the injection unit closer to the fixed mold.
In such a case, even if the user inputs an instruction by mistake, the contact between the injection unit and the fixed mold, which may cause the fixed platen to collapse or bend, is prohibited.

In the present invention, it is further determined whether the distance between the mold clamping determination unit that determines whether the fixed mold and the movable mold are clamped and the distance between the fixed mold and the injection unit is a predetermined value or less. A proximity determination unit that determines whether the determination of the mold clamping determination unit is “not clamped” and the determination of the proximity determination unit is “predetermined value”. , It is desirable to prohibit the movement of the injection unit by the contact / separation drive unit to approach the fixed mold.
In such a case, the injection unit can be moved regardless of the clamping state within a range where the distance between the fixed mold and the injection unit is not less than a predetermined value.

  According to the injection molding apparatus of the present invention, it is possible to manufacture a high-precision optical component with excellent surface-specific eccentricity by preventing the fixed mold from being displaced due to the falling or bending of the fixed platen.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. The present embodiment embodies the present invention as a lens molding apparatus for manufacturing a lens for a camera equipped with a mobile terminal. This embodiment is a molding apparatus for molding a small optical component having an outer diameter of 12 mm or less, and the optical component to be molded is required to have a surface roughness Ra of 20 nm or less. Further, this embodiment is applied to a micro injection molding apparatus having a mold clamping force of 150 kN or less.

  The lens molding apparatus of this embodiment is configured as shown in FIG. That is, the fixed platen 1 and the rear platen 3 are disposed on the frame 2. These platens are fixed to the frame 2. When these platens are viewed from the side in FIG. 1, they are almost square. Four tie bars 4 are installed between the stationary platen 1 and the rear platen 3. The tie bars 4 are arranged at the four corners of the fixed platen 1 and the rear platen 3, are fixed to the fixed platen 1 and the rear platen 3, and are parallel to each other.

  A movable platen 5 is disposed between the fixed platen 1 and the rear platen 3. The movable platen 5 is substantially square when viewed from the side in FIG. 1, and each tie bar 4 penetrates the vicinity of the four corners. The movable platen 5 is slidable with respect to each tie bar 4. A fixed mold 7 is attached to the surface of the fixed platen 1 on the movable platen 5 side. A movable mold 8 is attached to the surface of the movable platen 5 on the fixed platen 1 side.

  An injection unit 11 is provided on the back side of the fixed platen 1 on the movable platen 5 side. The injection unit 11 has an injection part 12, a cylinder 13, a nozzle 14, and a hopper 15. The resin material supplied from the hopper 15 is plasticized in the cylinder 13 and conveyed to the nozzle 14. The molten resin stored in the nozzle 14 is injected by the injection unit 12. The injection unit 12 is fixed to the carriage 16 and placed on the slide base 17.

  The injection unit 11 is provided with a nozzle touch mechanism 20. For this purpose, a ball screw 21 is attached to the carriage 16, and a gear 22 is screwed to the ball screw 21. A gear 23 meshes with the gear 22, and the gear 23 is driven by a servo motor 24. The servo motor 24 is provided with a counter 25 that measures the rotation speed. Therefore, the carriage 16 can be slid in the left-right direction in the figure on the slide base 17 by driving the servo motor 24. Thus, the injection unit 11 can make the nozzle 14 contact and separate from the fixed mold 7.

  On the other hand, a mold clamping mechanism 30 is provided between the rear platen 3 and the movable platen 5. FIG. 1 illustrates a single toggle type mold clamping mechanism 30. The mold clamping mechanism 30 has a screw 31, and the link 32 is opened and closed by the rotation of the screw 31. The screw 31 is rotated by a servo motor 33 through a gear in the gear box 34. The servo motor 33 is attached with a pulse encoder 35 for acquiring the rotation amount.

  In this embodiment, the control unit 40 controls the nozzle touch mechanism 20 and the mold clamping mechanism 30 in association with each other. The control unit 40 includes motor drive devices 41 and 42, a nozzle position determination unit 43, a mold clamping force determination unit 44, and a controller 45. The motor drive device 41 drives the servo motor 24. The motor driving device 42 drives the servo motor 33. The nozzle position determination unit 43 determines the position of the nozzle 14 based on the output of the counter 25. The mold clamping force determination unit 44 determines the mold clamping force based on the output of the pulse encoder 35. The controller 45 controls the motor drive devices 41 and 42 based on the results of the nozzle position determination unit 43 and the mold clamping force determination unit 44.

  Furthermore, an input unit 51 and a display unit 52 are connected to the controller 45. The input unit 51 receives various instruction inputs by the user. User instruction inputs include nozzle touch instructions, mold clamping instructions, injection instructions, mold opening instructions, and the like. The display unit 52 displays the driving status of the lens molding device, various warnings, and the like.

  In the injection unit 11, the resin supplied from the hopper 15 is melted and plasticized. The kind of the molten resin to be used may be one described in, for example, Japanese Patent Application Laid-Open No. 2004-144951, Japanese Patent Application Laid-Open No. 2004-144953, and Japanese Patent Application Laid-Open No. 2004-144554. The molten resin is weighed by a predetermined amount and stored in the nozzle 14 and its base.

  At the time of injection molding, the user inputs a mold clamping instruction through the input unit 51. In response to this, the controller 45 drives the servo motor 33 by the motor driving device 42 to clamp the mold. That is, the link 32 is opened when the screw 31 is rotated by the servo motor 33. Then, the movable platen 5 is moved in the right direction in the figure. Then, the fixed mold 7 and the movable mold 8 are clamped with a predetermined clamping force. The clamping force is about 68.8 kN, for example.

  Further, the user inputs a nozzle touch instruction and an injection instruction. In response to this, the controller 45 drives the servo motor 24 by the motor driving device 41 to apply the nozzle touch pressure. That is, the servo motor 24 is driven until the counter 25 reaches a predetermined rotational speed, and the carriage 16 is slid leftward in the figure. The nozzle 14 is pressed against the fixed mold 7 with a predetermined nozzle touch pressure. The nozzle touch pressure is about 5.1 kN, for example. The injection unit 12 then injects the molten resin stored in the nozzle 14 into the cavity between the two molds.

  Here, in the lens molding apparatus according to the present embodiment, even when the user erroneously inputs a procedure, it is prohibited to apply the nozzle touch pressure when the mold is not in the clamped state. That is, when an instruction to apply the nozzle touch pressure is input in a state where the mold is not clamped, a warning display is displayed on the display unit 52 by the controller 45, and the nozzle 14 and the fixed mold 7 are not in contact with each other. Stopped at position.

  Therefore, in this embodiment, when receiving an instruction to bring the nozzle 14 and the fixed mold 7 closer, the controller 45 first determines the position of the nozzle 14 by the nozzle position determination unit 43. The nozzle 14 is allowed to move in a range where the distance between the nozzle 14 and the fixed mold 7 is not close to a predetermined value or less. Therefore, in this range, the servo motor 24 is driven by the motor driving device 41 in accordance with a user operation. This distance is about 100 mm, for example, and the nozzle 14 and the fixed mold 7 are not in contact with each other in this state. That is, in this embodiment, when the movement of the injection unit 11 in a range where the nozzle 14 and the fixed mold 7 are not in contact with each other is required, the injection unit 11 can be moved regardless of the clamping state. The distance between the nozzle 14 and the fixed mold 7 is always determined by the nozzle position determination unit 43.

  When receiving an instruction to move the nozzle 14 closer to the fixed mold 7 or apply an nozzle touch pressure than a predetermined distance, the controller 45 confirms the mold clamping state. That is, the mold clamping force determination unit 44 determines whether a predetermined mold clamping force is applied between the molds 7 and 8. The mold clamping force determination unit 44 determines whether or not a predetermined mold clamping force is applied from the output of the pulse encoder 35. As a result, when it is determined that a predetermined mold clamping force is applied, the nozzle touch pressure is applied according to the user's operation.

  On the other hand, when it is determined that the predetermined mold clamping force is not applied, the driving of the servo motor 24 by the motor driving device 41 is stopped. Then, for example, “not clamped” is displayed on the display unit 52. The user can notice an error in the procedure by viewing this display. Then, before applying the nozzle touch pressure, first, a mold clamping instruction is input. Thereby, it is prevented that only the nozzle touch pressure is applied to the fixed platen 1 in a state where the mold clamping force is not applied. That is, the state as shown in FIG. 3 and FIG.

  As described in detail above, according to the lens molding apparatus of this embodiment, the mold clamping state is always applied when the nozzle touch pressure is applied. Therefore, the fixed platen 1 is not bent by the nozzle touch pressure. This prevents the displacement of the stationary mold 7 due to the tilting and deflection of the stationary platen 1, thereby providing a lens molding apparatus capable of producing a high-precision optical component with excellent surface-specific eccentricity.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, the means for driving the movable platen 5 is not limited to an electric ball screw. Hydraulic press system, hydraulic cylinder system, hydraulic toggle system, electric motor cylinder system, electric motor toggle system, etc. The nozzle touch mechanism 15 is not limited to the electric ball screw system. A method of pulling the stationary platen 1 toward the injection unit 11 by a hydraulic cylinder or the like may be used. Furthermore, a plurality of drive units for applying the nozzle touch pressure may be provided and applied at two or more locations.

  The present invention can also be applied to a frame support type lens molding apparatus that receives the load of the movable platen 5 at the frame 2. In the case of this frame support system, a configuration with a support such as an LM guide may be used. The total number of tie bars is not limited to “4”.

It is a front view which shows schematic structure of the lens shaping | molding apparatus which concerns on this form. It is a conceptual diagram of the conventional injection molding machine. It is a front view of the conventional injection molding machine. It is a front view of the conventional injection molding machine. It is a top view of the conventional injection molding machine. It is a top view of the conventional injection molding machine.

Explanation of symbols

7 Fixed mold 8 Movable mold 11 Injection unit 24, 33 Servo motor 41, 42 Motor drive device 43 Nozzle position determination unit 44 Clamping force determination unit 45 Controller 51 Input unit

Claims (3)

A fixed mold, a movable mold that can be brought into and out of contact with the fixed mold, and an anti-molding surface side of the fixed mold are melted in the gap between the two molds. An injection molding apparatus that simultaneously forms a plurality of optical components having an outer diameter of 12 mm or less and a surface roughness Ra of 20 nm or less.
A mold clamping drive unit that moves the movable mold to the fixed mold and clamps the mold;
A contact / separation drive unit for contacting and separating the injection unit with respect to the fixed mold;
And a prohibiting portion for prohibiting the contact of the injection unit to the fixed mold by the contact / separation driving unit in a state where the fixed mold and the movable mold are not clamped. Injection molding equipment. The injection molding apparatus according to claim 1,
An input unit that receives a user operation related to driving of the injection unit by the contact / separation driving unit;
In the state where the fixed side mold and the movable side mold are not clamped, the prohibiting unit is configured to place the injection unit by the contact / separation driving unit on the fixed side regardless of the operation of the input unit by a user. An injection molding apparatus characterized by prohibiting an operation to approach a mold. The injection molding apparatus according to claim 1 or 2,
A mold clamping determination unit that determines whether or not the fixed mold and the movable mold are clamped;
A proximity determination unit that determines whether or not a distance between the fixed mold and the injection unit is a predetermined value or less,
The prohibiting unit is configured to perform the injection by the contact / separation driving unit when the determination of the mold clamping determination unit is “not clamped” and the determination of the proximity determination unit is “predetermined value” or less. An injection molding apparatus characterized by prohibiting an operation of bringing a unit close to the fixed mold.

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