JP4261331B2 - Induction heating molding equipment - Google Patents

Description

  The present invention is an induction heating apparatus that independently heats each of a pair of molds by induction heating by two induction coils that are driven independently, and more specifically, the induction heating apparatus and the mold The present invention relates to an induction heating molding apparatus for manufacturing an optical element product by heating an optical element material to a desired temperature and molding the optical element material into a desired shape.

  In FIG. 6, the structure of the conventional induction heating molding apparatus is shown. The induction heating molding apparatus Fc includes a pair of mold sets 4 including an upper mold 4a having an upper molding surface FS1 and a lower mold 4b having a lower molding surface FS2 for molding an optical element material OM (not shown). Is used. The upper die 4a is induction heated by the upper induction coil 3a, and the lower die 4b is induction heated by the lower induction coil 3b. The heat of the die set 4 that has been induction-heated is transmitted to the optical element material OM through the molding surface FS. That is, the temperature of the optical element material OM is realized by controlling the temperatures of the upper mold 4a and the lower mold 4b. In other words, the temperature of the upper mold 4a and the lower mold 4b is controlled by changing the amounts of the upper magnetic flux Φa irradiated from the upper induction coil 3a and the lower magnetic flux Φb irradiated from the lower induction coil 3b. For this purpose, the mold set 4 is made of a magnetic material so as to be easily heated by induction heating.

  An inverter 1 that supplies electric power for generating a magnetic flux Φ for induction heating the mold set 4, and an upper transformer 2 a and a lower transformer 2 b are provided. Further, an upper mold actuator 6a and a lower mold actuator 6b for moving the upper mold 4a and the lower mold 4b, respectively, for insertion of the optical element material OM into the mold set 4, pressure molding, and removal after molding. Is provided. Upper transformer 2a and lower transformer 2b convert the heating power supplied from inverter 1 into voltages suitable for upper induction coil 3a and upper induction coil 3a, respectively. Furthermore, in order to implement | achieve a desired shaping | molding process, the controller 8 which controls the actuator 6 while controlling the temperature of the metal mold | die set 4 is further provided.

  In order to improve the releasability when removing the optical element product from the mold set 4, it is necessary to control the thermal expansion between the upper mold 4a and the lower mold 4b and the optical element product. For this purpose, it is necessary to independently adjust the temperatures of the upper mold 4a and the lower mold 4b. From this point of view, it is desirable that the upper induction coil 3a and the lower induction coil 3b are not driven by the common inverter 1, but are independently and continuously controlled by separate inverters.

  However, since the magnetic flux Φa of the upper induction coil 3a and the magnetic flux Φb of the lower induction coil 3b are on the same axis, if the upper induction coil 3a and the lower induction coil 3b are independently and continuously controlled by separate inverters, the upper induction coil The upper magnetic flux Φa generated in 3a and the lower magnetic flux Φb generated in the lower induction coil 3b interfere with each other (Φa + Φb), and an induced electromotive force is applied to the other inverter circuit element by inductive coupling. This induced electromotive force cannot be consumed and may damage circuit elements such as inverter elements.

  In order to prevent such a situation, in the induction heating molding apparatus Fc, the upper changeover switch 7a and the lower changeover switch are exclusively connected to the two upper induction coils 3a, the lower induction coil 3b, and the common inverter 1. 7b is provided. That is, by driving the upper induction coil 3a and the lower induction coil 3b exclusively and intermittently, the occurrence of mutual interference (Φa + Φb) is prevented without simultaneously generating the upper magnetic flux Φa and the lower magnetic flux Φb.

In addition, an induction heating molding apparatus (Patent Document 2) that simultaneously drives the upper induction coil 3a and the lower induction coil 3b while suppressing mutual interference between the upper magnetic flux Φa and the lower magnetic flux Φb has been proposed. In the induction heating molding apparatus, the resonance frequencies of the upper mold and the lower mold are set to different values. And by changing the oscillation frequency of the inverter around the resonance frequency, the current flowing through the upper induction coil wound around the upper mold and the lower induction coil wound around the lower mold is controlled, and the upper and lower mold temperatures are made independent. To control.
JP-A-4-58491 JP-A-6-64932

  In the induction heating molding apparatus (Patent Document 1) that exclusively and intermittently drives and controls the upper induction coil and the lower induction coil, the heat generation amounts of the upper mold and the lower mold can be controlled only alternately and intermittently. In other words, the upper and lower mold temperatures are discontinuous and can only be controlled with a large temperature difference. With such a rough temperature control, it is very difficult to control the quality of the optical element product obtained by homogenizing components by convection during heating of the optical element material OM and suppressing internal stress during cooling.

  Further, in the induction heating molding apparatus (Patent Document 2) that continuously drives the upper induction coil and the lower induction coil by changing the oscillation frequency of the inverter around the above-described resonance frequency, the resonance point of the circuit is deviated. Since it is necessary to drive the inverter at the part, there is a problem that power reflection occurs regularly and the efficiency of the inverter decreases.

  Therefore, the present invention continuously drives the independent upper induction coil and the lower induction coil for individually heating the upper mold and the lower mold used for the thermoforming of the optical element product, and mutually controls the magnetic flux generated from each coil. It is an object of the present invention to provide an induction heating molding apparatus capable of preventing temperature on an inverter due to interference and enabling continuous, precise and efficient temperature control.

The first and second molds used in opposition to each other are induction-heated by the first magnetic flux and the second magnetic flux generated continuously and individually, and the first and second molds are inductively heated. An induction heating molding apparatus for melting and press-molding an optical element material inserted therein is provided around the first molding die to generate the first magnetic flux, and the first magnetic flux generating means, A second magnetic flux generating means provided around the two molds for generating the second magnetic flux, and between the first magnetic flux generating means and the second magnetic flux generating means, Magnetic flux interference prevention means (20, 13c) provided at a position where the second magnetic fluxes overlap and interfere with each other to cancel the action of magnetic flux components that interfere with each other between the first magnetic flux and the second magnetic flux. with the door, the magnetic flux interference preventing means, the magnetic flux component Among them, the magnetic flux component of the first magnetic flux penetrating the second magnetic flux generation means and the magnetic flux component of the second magnetic flux penetrating the first magnetic flux generation means are converted into current and heat and consumed. a magnetic flux absorbing means, Ru provided with a cooling mechanism for cooling the heating of the magnetic flux absorbing means.

  As described above, in the induction heating apparatus according to the present invention, the upper induction coil and the lower induction coil are generated simultaneously with the upper magnetic flux and the lower magnetic flux by continuously and precisely driving and controlling the upper induction coil and the lower induction coil. Continuous and precise temperature control is possible. Furthermore, mutual interference between the generated upper magnetic flux and lower magnetic flux is prevented, thereby preventing a burden on the inverter. As a result, the temperature of the optical element material can be controlled continuously, rapidly and precisely.

  Before describing the embodiment of the present invention in detail, the basic concept of the induction heating molding apparatus according to the present invention will be described. As described above, in the thermoforming of the optical element product, it is highly desirable to control the heat generation of the upper mold and the lower mold individually and continuously. In other words, factors such as the uniformity of components due to convection and heat distribution when optical element materials are heated and melted, the effect of pressure during pressure molding, and the residual stress and component distribution during cooling are the main factors. It is no exaggeration to say that it is determined only by the accuracy of heat generation control of the mold.

  From this point of view, in the present invention, an induction heating device is adopted with an upper induction coil and a lower induction coil that are driven independently from each other in order to quickly heat the mold and easily control the temperature. Has been. In the induction heating apparatus, as described above, there is a problem of magnetic flux interference generated between the upper induction coil and the lower induction coil. In the conventional induction heating molding apparatus, the occurrence of magnetic flux interference itself is prevented at the expense of temperature control quality and temperature control efficiency. However, in the induction heating molding apparatus according to the present invention, generation of magnetic flux interference is allowed, and the generated magnetic flux interference is converted into thermal energy, thereby ensuring temperature control quality and temperature control efficiency. Below, the induction heating molding apparatus which concerns on various embodiment of this invention is demonstrated concretely.

(First embodiment)
Below, with reference to FIG. 1 and FIG. 2, the induction heating molding apparatus which concerns on this embodiment is demonstrated. As shown in FIG. 1, the induction heating molding apparatus F1 includes an upper mold 14a having an upper molding surface FS1 for molding an optical element material OM (not shown) and a lower mold 14b having a lower molding surface FS2. A pair of mold sets 4 is used. An upper inverter 11a for supplying inductive power is connected to the upper induction coil 13a via an upper transformer 12a. Similarly, the lower inverter 11b is connected to the lower induction coil 13b via the lower transformer 12b.

  The upper die 14a is induction heated by the upper induction coil 13a, and the lower die 14b is induction heated by the lower induction coil 13b. The heat of the die set 14 induction-heated is transmitted to the optical element material OM through the molding surface FS. That is, the temperature of the optical element material OM is realized by controlling the temperatures of the upper mold 14a and the lower mold 14b. In other words, the amounts of the upper magnetic flux Φa irradiated from the upper induction coil 13a and the lower magnetic flux Φb irradiated from the lower induction coil 13b are changed to control the temperatures of the upper mold 14a and the lower mold 14b.

  For this reason, as the material of the mold set 14, the inside of the mold is heated to a desired temperature, for example, when the optical element material OM is a glass material, it is heated to 600 ° C. SUS410 or NiAl is used. Further, ceramic is used for the molding surface FS that comes into contact with the optical element material OM, and it is difficult to adhere even if the glass material is melted.

  Further, the upper mold actuator 19a and the lower mold actuator 19b are moved to move the upper mold 14a and the lower mold 14b, respectively, for insertion of the optical element material OM into the mold set 14, pressure molding, and removal after molding. Is provided. The upper transformer 12a and the lower transformer 12b convert the heating power supplied from the upper inverter 11a and the lower inverter 11b into voltages suitable for the upper induction coil 13a and the upper induction coil 13a, respectively. Further, in order to realize a desired molding process, a controller 17 is further provided for continuously controlling the temperatures of the upper mold 14a and the lower mold 14b of the mold set 14 individually and controlling the actuator 19.

  As shown in FIG. 2, a magnetic flux shielding material 20 is provided between the upper induction coil 13a and the lower induction coil 13b. Specifically, the magnetic flux blocking material 20 is provided at a position where the upper magnetic flux Φa generated from the upper induction coil 13a and the lower magnetic flux Φb generated from the lower induction coil 13b overlap each other and cause mutual interference (Φa + Φb). That is, paying attention to the fact that the magnetic flux weakens in inverse proportion to the distance from the conducting wire through which the current flows, insert a magnetic flux shielding material between the upper and lower coils 13a and 13b, which has the highest magnetic flux density and causes mutual interference. Thus, magnetic flux interference can be prevented, and the temperatures of the upper and lower molds 14a and 14b can be continuously adjusted independently by the two inverters 11a and 11b. In order to satisfy this function, the magnetic flux shielding material 20 is configured in a donut shape that is hollowed out by a disk having a thickness of about 10 mm, for example. This is because the optical element material OM to be heated is inserted between the upper mold 14a and the lower mold 14b, so that the part other than the part in contact with the optical element material OM of the mold set 14 can be shielded from the magnetic flux Φ as much as possible. I have to. The magnetic flux blocking material 20 may be configured in any other shape as long as such an effect can be obtained.

  A method for manufacturing an optical element product in the induction heating molding apparatus F1 will be briefly described. When the mold set 14 is filled with the optical element material OM, the actuator unit 19 is driven to separate the upper mold 14a and the lower mold 14b, so that a space that can be filled with the optical element material OM is generated therebetween. . For example, when forming a glass ball having a diameter of about 10 mm, the shortest distance between the upper mold 14a and the lower mold 14b may be about 30 mm.

  After the glass sphere is filled as the optical element material OM, the distance between the upper mold 14a and the lower mold 14b is reduced. When narrowing the interval, the position of either the upper mold 14a or the lower mold 14b is fixed, the other mold is moved until it comes into contact with the glass ball, and a constant load, for example, about 20 kgf is applied. The mold set 14 is induction-heated. The glass sphere (optical element material OM) is heated and softened by the heat generated in the exothermic molded body FH. Specifically, the upper induction coil 13a is wound around the outer periphery of the upper mold 14a, and when high frequency power, for example, 23 kHz, is applied to the upper induction coil 13a, a magnetic flux is generated inside the upper induction coil 13a, and the upper mold 14a When the upper magnetic flux Φa passes through, the induction current I flows inside the heating material and is induction-heated by Joule heat due to the electric resistance inside the heating material. The lower die 14b is induction-heated by the lower induction coil 13b wound around the outer periphery in the same manner as the upper die 14a.

  A mutual interference magnetic flux Δ (Φa + Φb) that causes mutual interference between the upper magnetic flux Φa and the lower magnetic flux Φb is absorbed by the magnetic flux blocking material 20. That is, the interference component of the upper magnetic flux Φa generated from the upper induction coil 13a, that is, the component Δ (Φa) penetrating the lower induction coil 13b is absorbed and blocked by the magnetic flux blocking material 20 and does not reach the lower induction coil 13b. Similarly, the interference component of the lower magnetic flux Φb generated from the lower induction coil 13b, that is, the component Δ (Φb) penetrating the upper induction coil 13a is absorbed and blocked by the magnetic flux blocking material 20 and does not reach the upper induction coil 13a. . The absorbed interference magnetic flux Δ (Φa + Φb) is converted into heat by the magnetic flux blocking material 20 and consumed.

  Thus, even if the upper induction coil 13a and the lower induction coil 13b are continuously driven simultaneously, the mutual interference magnetic flux Δ (Φa + Φb) generated by the upper magnetic flux Φa and the lower magnetic flux Φb is equal to the upper inverter 11a and the lower inverter 11b. Will not be adversely affected. Further, since the resonance frequency of the upper induction coil 13a and the lower induction coil 13b is the same, the heating efficiency is not lowered. The heat generated by the magnetic flux shielding material 20 due to the absorbed mutual interference magnetic flux Δ (Φa + Φb) is released to the outside of the induction heating molding apparatus F1 by natural air cooling. However, if natural air cooling is insufficient, a forced air cooling or forced water cooling, or a cooling mechanism for circulating a refrigerant or the like may be provided.

  The optical element material OM that has been softened by heating, that is, melted and elastic, is pressurized and deformed by a pressure of about 350 kgf applied by the actuator unit 19. Further, in order to transfer the shape of the optical element product to the optical element material OM by the molding surface FS of the mold, the mold set 14 is lowered to about 550 ° C. and at the same time, the pressing load for molding is reduced to about 50 kgf. And molded as an optical element product.

  The temperature of the mold set 14 is determined based on the temperature T1 of the upper mold 14a (hereinafter referred to as “upper mold temperature T1”) and the temperature T2 of the lower mold 14b (referred to as “upper mold temperature T2”). The The temperature of the upper molding surface FS1 is measured by the upper mold temperature measuring means 18a inserted into the upper mold 14a and is input to the controller 17 as the upper mold temperature T1. Similarly, the temperature of the lower molding surface FS2 is measured by the lower mold temperature measuring means 18b inserted into the lower mold 14b and is input to the controller 17 as the lower mold temperature T2. The controller 17 calculates a desired operation amount using a generally known PID control method based on the input upper mold temperature T1 and lower mold temperature T2 and the target temperature. The controller 17 further adjusts the output power of the upper inverter 11a and the lower inverter 11b in accordance with the calculated operation amount, thereby realizing temperature tracking control to the target temperature.

  The optical element product molded by such a series of molding processes is taken out of the mold set 14 by the actuator unit 19 with the interval between the upper mold 14a and the lower mold 14b being increased. At this time, in order to improve workability by releasing the mold in a certain procedure and to safely take out the molded product from the mold, the optical element product is first released from the upper mold 14a, and then the lower mold 14b is released. Let For this purpose, for example, the upper mold temperature T1 is lowered while the upper mold temperature T1 is maintained about 100 ° C. higher than the lower mold temperature T2.

For example, when the upper mold temperature T1 reaches 450 ° C. and the lower mold temperature T2 reaches 550 ° C., the actuator unit 19 is driven to move the upper mold 14a upward to release the optical element material. After releasing the upper mold 14a, the lower mold temperature T2 is lowered to near room temperature RT, and the optical element product is taken out from the lower mold 14b.

  As described above, in this embodiment, focusing on the fact that the magnetic flux is weakened in inverse proportion to the distance from the conducting wire through which the current flows, the magnetic flux is shielded between the upper and lower coils where the magnetic flux density is highest and mutual interference is a problem. A material is inserted to prevent magnetic flux interference. As a result, the upper and lower mold temperatures can be adjusted independently by the two inverters, the upper and lower molds are kept at a desired temperature difference, and mold release after molding is facilitated.

(Second Embodiment)
Below, with reference to FIG. 3 and FIG. 4, the induction heating molding apparatus which concerns on this embodiment is demonstrated. As shown in FIG. 3, the induction heating forming apparatus F2 according to the present embodiment is the same as the induction heating forming apparatus F1 shown in FIG. The transformer 12b is replaced with a lower transformer 12c. The lower transformer 12c is provided with a secondary coil for driving the magnetic flux interference prevention induction coil 13c in the lower transformer 12b. Since the other parts are configured in the same manner as the induction heating forming apparatus F1, the magnetic flux interference prevention induction coil 13c and the lower transformer 12c will be described mainly.

  As shown in FIG. 4, the magnetic flux interference prevention induction coil 13 c is provided between the upper induction coil 13 a and the lower induction coil 13 b similarly to the magnetic flux shielding material 20. This is intended to cancel the mutual interference magnetic flux Δ (Φa + Φb) caused by the upper magnetic flux Φa generated from the upper induction coil 13a and the lower magnetic flux Φb generated from the lower induction coil 13b by the magnetic flux interference prevention induction coil ΔΦc.

  Specifically, in order to weaken the magnetic flux in the central portion where the upper induction coil 13a and the lower induction coil 13b approach, the magnetic flux interference prevention induction coil 13c generates a magnetic flux in the opposite direction to the upper induction coil 13a and the lower induction coil 13b. Thus, the coil is wound in the direction opposite to each other at the portion of the transformer 12. As a result, the magnetic fluxes penetrating the magnetic flux interference preventing induction coil 13c are opposite in direction to the upper induction coil 13a and the lower induction coil 13b, and thus cancel each other. In this case, if heat generation in the magnetic flux interference prevention induction coil 13c becomes a problem, an appropriate cooling means may be provided as necessary as in the induction heating molding apparatus F1.

  As described above, in the present embodiment, the third induction coil having a reverse current flow direction is inserted between the upper induction coil and the lower induction coil, which have the highest magnetic flux density and cause mutual interference. This makes it possible to weaken the magnetic flux near the upper and lower induction coils where magnetic flux interference is likely to occur, allowing the two inverters to adjust the upper and lower mold temperatures independently, creating a temperature difference between the upper and lower molds. Mold becomes easy.

  As described above, in the induction heating molding apparatus according to the present invention, magnetic flux interference generated between the upper induction coil 13a and the lower induction coil 13b is prevented, and continuous, precise, and efficient temperature control is possible. In particular, when removing the molded product from the mold, this temperature control is important in order to prevent the molded product from being dropped and damaged. Hereinafter, the induction heating molding method according to the present invention will be described in detail with reference to FIGS. 1 and 5.

  FIG. 5 shows a thermoforming process of the optical element material OM for producing an optical product by thermoforming. In the figure, the vertical axis T represents the temperature of the mold set 14, the vertical axis d represents the separation distance between the optical element material OM and the molding surface FS of the mold set 14, and the horizontal axis t represents each time in the molding process. Indicates. Further, the solid line La indicates the upper mold temperature T1, the two-dot chain line Lb indicates the lower mold temperature T2, and the solid line Lg indicates the heating distance d. The heating distance d actually corresponds to the distance between the upper molding surface FS1 of the upper mold 14a and the upper surface of the optical element material OM.

As shown in FIG. 5, the optical product includes a melting step S1, a molding step S2, a transfer step S3, an upper mold releasing step S4, an upper and lower mold separating step S5, a strain removing step S6, a lower mold releasing step S7, and an extraction step. It is completed through 8 steps of S8. Prior to the melting step S1, the optical element material OM is placed in the mold set 14 as follows. First, the distance between the upper mold 14a and the lower mold 14b is widened by the upper mold actuator 19a and the lower mold actuator 19b so that the optical element material OM can be inserted. This interval may be about 30 mm when a glass sphere (optical product) having a diameter of about 10 mm is formed, for example, and can be appropriately determined according to the size of the optical product to be manufactured. In this case, although depending on the curvatures of the upper molding surface FS1 and the lower molding surface FS2, the heating distance d is 20 mm (30-10 mm) or more.
Next, the optical element material OM is inserted between the upper mold 14a and the lower mold 14b. In this case, the optical element material OM is not in contact with the upper molding surface FS1 of the upper mold 14a, and is placed in a partial contact state on the lower molding surface FS2 on the lower mold 14b.

  In the melting step S1, the upper mold 14a and the lower mold 14b in which the optical element material OM is inserted are individually induction-heated to about 580 ° C. and about 560 ° C., respectively. As described above, the optical element material OM is not in contact with the upper molding surface FS1 of the upper mold 14a, and is in partial contact with the lower molding surface FS2 of the lower mold 14b. Therefore, the heat of the upper mold 14a is supplied to the optical element material OM by radiation, and the heat of the lower mold 14b is supplied by radiation together with direct conduction from the point contact portion. As described above, since the entire optical element material OM is heated at the same time mainly by the radiant heat (partially conductive heat) from the mold set 14, the optical element material OM is brought into contact with the upper molding surface FS1 and the lower molding surface FS2. In this state, it is heated much more uniformly than when it is partially heated mainly by conduction heat (partially radiant heat) from the mold set 14. As a result, the optical element material OM can greatly reduce the component ratio fluctuation and distortion generated during the partial heating, and is more uniformly heat-softened. That is, in the final stage of heating, it is possible to prevent a situation in which a portion that has not been softened remains in the optical element material OM. It goes without saying that the optical element material OM is preferably not in contact with the lower mold 14b from the viewpoint of more uniform heating. However, in reality, the optical element material OM may be prepared in a shape that makes the contact area as small as possible and approaches point contact.

  In the molding step S2, the upper mold 14a and the lower mold 14b are brought close to each other by the upper mold actuator 19a and the lower mold actuator 19b while maintaining the lower mold temperature T2 (Lb). As a result, the heat-softened optical element material OM is deformed following the upper molding surface FS1 and the lower molding surface FS2, and is molded into the shape of the optical product. At this time, a pressure (pressing load) of approximately 350 kgf is applied to the optical element material OM. In addition, either or both of the upper mold 14a and the lower mold 14b may be moved, but preferably the upper mold 14b is fixed in a state where the position of the lower mold 14b is fixed in order to stabilize the optical element material OM during molding. The mold 14a is moved.

  In the transfer step S3, the upper mold temperature T1 and the lower mold temperature T2 are lowered from about 560 ° C. to about 550 ° C., and the pressing load is reduced from about 350 kgf to about 50 kgf. As the mold temperature (T1, T2) is lowered, the temperature of the optical element material OM is also lowered, so that the heat softened state is changed to the normal rigid body state. Therefore, the heating distance d does not change substantially despite the change in the pressing load. As a result, the optical element material OM is completely deformed into the shapes of the upper molding surface FS1 and the lower molding surface FS2, and the outer shape of the optical product is transferred. The optical element material OM obtained in this step is hereinafter referred to as a transfer molded product OM as necessary.

  In addition, when the upper mold 14a and the lower mold 14b are heated at the heating distance d, it is assumed that the glass sphere temperature rise is delayed from the mold temperature rise in order to heat the glass sphere uniformly and at high speed. Therefore, it is also possible to control the upper and lower molds by overshooting the target temperature using a PID control method or the like. Furthermore, it is also possible to control so as to keep the temperature of the glass sphere constant by changing the mold temperature in accordance with the distance between the mold and the glass sphere.

  In the upper mold release step S4, the upper mold temperature T1 is lowered from 550 ° C. to 450 ° C. while the lower mold temperature T2 is maintained at 550 ° C. Due to the difference in coefficient of thermal expansion between the mold and the optical element material OM, the transfer molded product OM is separated from the upper mold 14a.

  In the upper and lower mold separation step S5, the distance between the upper mold 14a and the lower mold 14b is widened so that the transfer molded product can be taken out while the upper mold temperature T1 is controlled to 450 ° C. and the lower mold temperature T2 is controlled to 550 ° C.

In the strain removal step S6, the upper and lower mold intervals (d) and the upper and lower mold temperatures (T1 and T2) are maintained constant for a certain period (t _{5 to} t ₆ ). As a result, in the molding step S2 and the transfer step S3, distortion generated in the transfer molded product OM is removed.

  In the lower mold release step S7, the lower mold temperature T2 is lowered from 550 ° C. to near room temperature RT. Due to the difference in thermal expansion coefficient between the mold set 14 and the optical element material OM, the transfer molded product OM is separated from the lower mold 14b. At that time, the upper mold temperature T1 is also lowered from 450 ° C. to near room temperature RT. As a result, the optical product is completed.

  In the removal step S8, the optical product is stably placed on the lower molding surface FS2 without being fixed to either the upper mold 14a or the lower mold 14b. Therefore, the molded product can be taken out from the mold.

The above temperature control is realized as follows. That is, the upper mold temperature T1 and lower mold temperature T2 is measured by the upper mold temperature measuring unit 18a and the lower mold temperature measuring unit 18b inserted respectively, are input to the controller 17. Based on the measured temperature of the set target become temperature and the upper die 14a and lower die 14b by the control unit 17 calculates the desired manipulated variable using a control system such as PID control method commonly known By inputting the calculated operation amount to the external input means for adjusting the inverter output power, the temperature follow-up control to the target temperature is realized individually above and below.

  Further, the magnetic flux shielding material 20 inserted between the upper induction coil 13a and the lower induction coil 13b prevents interference between the magnetic flux generated by the upper induction coil 13a and the magnetic flux generated by the lower induction coil 13b. Temperature control is realized with high accuracy and efficiency. Moreover, as the magnetic flux shielding material 20, a low-resistance nonmagnetic material such as copper or brass is used. Since the object to be heated is inserted between the upper mold 14a and the lower mold 14b, as shown in FIG. 2, the shape of the magnetic flux shielding material 20 is, for example, about 10 mm thick so that the part other than the object to be heated can be shielded as much as possible. Use a donut shape that is hollowed out. When the shielding material generates heat due to the absorbed magnetic flux, a cooling mechanism may be provided in the magnetic flux shielding material 20 to circulate, for example, a refrigerant.

  When the optical element material is thermoformed by induction heating, it is useful as an induction heating molding apparatus or the like capable of more rapid and efficient temperature control by intensively induction heating the molding part.

The block diagram which shows the structure of the induction heating molding apparatus which concerns on the 1st Embodiment of this invention. Explanatory drawing of the positional relationship of the metal mold | set set shown in FIG. 1, an induction coil, and a magnetic flux blocker The block diagram which shows the structure of the induction heating molding apparatus which concerns on the 2nd Embodiment of this invention. Explanatory drawing of the positional relationship of the metal mold | die set shown in FIG. 3, an induction coil, and a magnetic flux interference prevention induction coil Time chart showing induction heating molding process Configuration block diagram of induction heating molding apparatus in the conventional example

Explanation of symbols

Fc, F1, F2 Induction heating molding apparatus 11a Upper inverter 11b Lower inverter 12a Upper transformer 12b Lower transformer 13a Upper induction coil 13b Lower induction coil 13c Magnetic flux interference prevention induction coil 14 Mold set 14a Upper mold 14b Lower mold FS Molding surface FS1 Upper molding surface FS2 Lower molding surface 17 Controller 19 Actuator unit 19a Upper mold actuator 19b Lower mold actuator 20 Magnetic flux blocking material

Claims (12)

The first and second molds used in opposition to each other are induction-heated by the first magnetic flux and the second magnetic flux generated continuously and individually, and the first and second molds are inductively heated. An induction heating molding apparatus for melt-pressing an optical element material inserted therein,
First magnetic flux generating means provided around the first mold for generating the first magnetic flux;
Second magnetic flux generating means provided around the second mold for generating the second magnetic flux;
The first magnetic flux generating means and the second magnetic flux generating means are provided at positions where the first and second magnetic fluxes overlap and interfere with each other, and the first magnetic flux and the second magnetic flux generation means Magnetic flux interference prevention means for canceling the action of magnetic flux components that interfere with each other with the magnetic flux of two ,
The magnetic flux interference prevention means includes a magnetic flux component of the first magnetic flux that penetrates the second magnetic flux generation means, and a magnetic flux of the second magnetic flux that penetrates the first magnetic flux generation means. a magnetic flux absorbing means for consumption by converting the component into a current and heat, inductive heating forming apparatus Ru provided with a cooling mechanism for cooling the heating of the magnetic flux absorbing means. 2. The induction heating molding apparatus according to claim 1 , wherein the magnetic flux interference prevention unit is configured in a ring shape around the first molding die and the second molding die. 3. The first and second molds used in opposition to each other are induction-heated by the first magnetic flux and the second magnetic flux generated continuously and individually, and the first and second molds are inductively heated. An induction heating molding apparatus for melt-pressing an optical element material inserted therein,
First magnetic flux generating means provided around the first mold for generating the first magnetic flux;
Second magnetic flux generating means provided around the second mold for generating the second magnetic flux;
Magnetic flux interference preventing means provided between the first magnetic flux generating means and the second magnetic flux generating means for canceling the action of magnetic flux components that interfere with each other between the first magnetic flux and the second magnetic flux. And
The magnetic flux interference prevention means includes a magnetic flux component of the first magnetic flux that penetrates the second magnetic flux generation means, and a magnetic flux of the second magnetic flux that penetrates the first magnetic flux generation means. An induction heating forming apparatus which is a magnetic flux erasing means for canceling the component with a third magnetic flux. 4. The induction heating apparatus according to claim 3 , wherein the direction of the third magnetic flux is opposite to the direction of the first magnetic flux and the second magnetic flux. 5. The first magnetic flux generation means includes a first induction coil wound in a first direction around the first mold,
The second magnetic flux generation means includes a second induction coil wound around the second mold in the first direction,
The induction heating forming apparatus according to claim 4 , wherein the magnetic flux erasing unit is a third induction coil wound in a direction opposite to the first direction. First heating control means for heating the first mold by the first magnetic flux;
Second heating control means for heating the second mold by the second magnetic flux,
2. The induction heating molding apparatus according to claim 1, wherein the first heating control unit heats the first molding die in a non-contact state with the optical element material. 3. The first and second molds used in opposition to each other are induction-heated by the first magnetic flux and the second magnetic flux generated continuously and individually, and the first and second molds are inductively heated. A molding method for melt-pressing an optical element material inserted therein,
A first heating step of heating the first mold to a first temperature for a first predetermined time in a state of being separated from the optical element material by a predetermined distance;
A second heating step in which the second mold is heated to a second temperature lower than the first temperature for the first predetermined time in a state where the optical element material is placed;
After the first and second heating steps, a temperature lowering and pressing step of lowering the first mold to the second temperature and pressing the first mold against the optical element material with the first pressure over a second predetermined time. When,
After the first and second heating steps, the second mold is held at the second temperature for the second predetermined time and the optical element material is resisted against the first pressure. A heat and pressure step for pressing,
The optical element material is thermally softened by the first and second heating steps, and the shape of the contact portion between the first mold and the second mold by the temperature drop pressurization step and the heat retention pressurization step. A forming method characterized by being formed into a shape. After the temperature drop pressurization step and the heat retention pressurization step,
Over the third predetermined time, the first and second molds are lowered from the second temperature to the third temperature, and the pressure pressing the optical element material is changed from the first pressure to the second temperature. to claim 7 in which a first and a cooling decompression step, the shape of the contact portion between the first and second mold to the optical element material the molded is characterized in that it is transferred to vacuum pressure The forming method as described. After the first temperature decreasing pressure reduction step,
Over the fourth predetermined time, the first mold is lowered to a fourth temperature, the pressure pressing the optical element material is reduced from the second pressure to the third pressure, and the second The molding method according to claim 8 , further comprising: a second temperature lowering and depressurizing step for maintaining the mold at the third temperature, wherein the optical element material is separated from the first mold. After the second temperature decreasing pressure reduction step,
The molding according to claim 9 , further comprising a separation step of separating the first and second molding dies from each other over a fifth predetermined time and holding them at the fourth temperature and the third temperature, respectively. Method. After the spacing step,
A temperature holding step of holding each of the first and second molds at the fourth temperature and the third temperature for a sixth predetermined time, and internal strain of the optical element material is removed; The molding method according to claim 10 . After the temperature holding step,
A step of lowering the temperature of the second mold from the third temperature to the fifth temperature over a seventh predetermined time, wherein the optical element material is separated from the second mold. The molding method according to claim 11 , wherein the molding method is characterized in that:

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