JP2021079682A - Dielectric heating molding device and dielectric heating molding method - Google Patents

Abstract

To provide a dielectric heating molding device 1 that can increase the degree of freedom in a size, shape or the like of a molded product to be molded, and a dielectric heating molding method.SOLUTION: A dielectric heating molding device 1 comprises a mold 2 and a dielectric heating source 6. The mold 2 is a material having an insulating property that generates heat due to dielectric loss, and has a cavity 20 in which a molded body 8 is molded from a molding material 80. The dielectric heating source 6 applies an alternating electric field Y to the molding material 80 and the molding die 2 in the cavity 20 by an AC voltage applied between a pair of electrodes 61 arranged on both sides of the mold 2 to heat the molding material 80 in the cavity 20.SELECTED DRAWING: Figure 3

Description

The present invention relates to a dielectric heating molding apparatus and a dielectric heating molding method.

As a method for molding a resin molded product such as a thermoplastic resin, there are an injection molding method, a blow molding method, a press molding method and the like. In these molding methods, a mold which is a metal molding mold is used. When manufacturing a mold, it is necessary to cut a metal material three-dimensionally, and this cutting process has a weakness that it takes time and effort. On the other hand, as a molding method that enables molding of a thermoplastic resin without using a molding mold, there is a layered molding method known as a 3D printer or the like. While the additive manufacturing method does not require a molding die, it has a weakness in characteristics due to the remaining laminated interface remaining in the molded resin molded product. As a molding method in which the weaknesses of these molding methods are overcome, for example, there are a molding mold made of a non-metallic material and a molding method of a thermoplastic resin using electromagnetic waves, which are shown in Patent Documents 1 and 2.

In the resin molding method of Patent Document 1, a rubber mold is used instead of the mold, and the thermoplastic resin in the cavity of the rubber mold is heated by the electromagnetic waves emitted from the surface of the rubber mold to form the thermoplastic resin. A molded product is obtained. In this resin molding method, the inside of the rubber mold cavity is evacuated by vacuum means, and the cavity is easily filled with the thermoplastic resin.

Further, in the molding method of the thermoplastic resin molded product of Patent Document 2, when the thermoplastic resin in the rubber mold is heated by the electromagnetic wave, the pressure in the rubber mold becomes lower than the external pressure by the vacuum means. The pair of rubber mold portions constituting the rubber mold come close to each other, and the thermoplastic resin molded product is molded in the rubber mold having a reduced volume.

JP-A-2007-216448 Japanese Unexamined Patent Publication No. 2011-240539

In the method for molding a thermoplastic resin shown in Patent Documents 1 and 2, electromagnetic waves such as near infrared rays and microwaves are used, and the molding material in the cavity of the molding die is generated by the electromagnetic waves emitted from the outside of the molding die. Is heated. Therefore, for example, when molding a large molded body, a molded body having a complicated shape, or the like, it has been found that it is difficult for the entire molding material in the cavity to be irradiated with electromagnetic waves. Therefore, in particular, it is desired to develop a molding die made of a non-metal material and a heating method using electromagnetic waves, which are effective for molding a large molded body, a molded body having a complicated shape, and the like.

The present invention has been made in view of the above problems, and has been obtained in an attempt to provide a dielectric heating molding apparatus and a dielectric heating molding method capable of increasing the degree of freedom in the size, shape, etc. of a molded product to be molded. ..

The first aspect of the present invention is
An insulating molding die that has a cavity in which a molded product is molded from a molding material and has the property of generating heat due to dielectric loss.
A dielectric heating source that heats the molding material in the cavity and the molding material in the cavity by applying an alternating electric field to the molding material and the molding die by an AC voltage applied between a pair of electrodes arranged on both sides of the molding die. And in a dielectric heating molding apparatus.

The second aspect of the present invention is
A placement step in which the molding material is placed in an insulating molding cavity that has the property of generating heat due to dielectric loss.
A dielectric heating source is used, and an alternating electric field is applied to the molding material in the cavity and the molding die by an AC voltage applied between a pair of electrodes of the dielectric heating source arranged on both sides of the molding die. A heating step in which the molding material in the cavity is heated, and
A dielectric heating molding method comprising a cooling step of cooling the molding die and the molding material to obtain a molded product from the molding material.

(Dielectric heating molding apparatus of the first aspect)
The dielectric heating molding apparatus enables molding of a molded product having a large size, a complicated shape, or the like by using a dielectric heating source having a pair of electrodes.

When molding a molded product, a molding mold in which a molding material is arranged in a cavity is arranged between a pair of electrodes in a dielectric heating source. Next, when an AC voltage is applied between the pair of electrodes, an alternating electric field is applied to the molding material and molding mold in the cavity. Then, the molding material in the cavity generates heat due to the dielectric loss, or the molding material in the cavity is heated by heat transfer from the molding mold that generates heat due to the dielectric loss, and the molding material melts. After that, the molding material is cooled and solidified to obtain a molded product.

In the dielectric heating molding apparatus, all or part of the molding die is arranged between the pair of electrodes. Then, the alternating electric field is applied to the molding material in the cavity located in the whole or a part of the molding mold arranged between the pair of electrodes and in the whole or a part of the molding mold arranged between the pair of electrodes. It is applied. When the molding die generates heat by using an alternating electric field generated by an AC voltage, it is possible to generate heat to a deeper position of the molding die as compared with the case where the molding die generates heat by using microwaves. Therefore, even if the molded body to be molded in the cavity is large or has a complicated shape, the portion of the molding material arranged between the pair of electrodes is applied to this portion. It can be melted more appropriately by the alternating electric field, and the molded product can be appropriately molded.

When a part of the molding die is arranged between the pair of electrodes, the molding die is moved relative to the pair of electrodes, and the molding material is located in each part in the cavity of the molding die. Can be sequentially melted.

Therefore, according to the dielectric heating molding apparatus, it is possible to increase the degree of freedom in the size, shape, etc. of the molded product to be molded.

(Dielectric heating molding method of the second aspect)
In the dielectric heating molding method, a placement step, a heating step, and a cooling step are performed to mold a molded product from a molding material. In particular, in the heating step, a dielectric heating source is used to more appropriately melt the part of the molding material placed between the pair of electrodes.

Therefore, according to the dielectric heating molding method, it is possible to increase the degree of freedom in the size, shape, etc. of the molded product to be molded, as in the case of the dielectric heating molding apparatus.

FIG. 1 is a cross-sectional view showing a dielectric heating molding apparatus according to the first embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. 1 showing a dielectric heating molding apparatus according to the first embodiment before depressurizing the inside of the decompression bag. FIG. 3 is a sectional view taken along line III-III of FIG. 1 showing a dielectric heating molding apparatus after depressurizing the inside of the decompression bag according to the first embodiment. FIG. 4 is a sectional view taken along line IV-IV of FIG. 1 showing a dielectric heating molding apparatus after depressurizing the inside of the decompression bag according to the first embodiment. FIG. 5 is a cross-sectional perspective view showing a molding die divided into a plurality of split die portions according to the first embodiment. FIG. 6 is a cross-sectional view showing another molding mold according to the first embodiment. FIG. 7 is a perspective view showing the dielectric heating molding apparatus in the state where the pressure reducing bag is opened according to the first embodiment. FIG. 8 is an enlarged perspective sectional view showing the periphery of the opening chuck that closes the opening of the decompression bag according to the first embodiment. FIG. 9 is a perspective sectional view showing an example of the molded product according to the first embodiment. FIG. 10 is a cross-sectional view showing another dielectric heating molding apparatus according to the first embodiment. FIG. 11 is a cross-sectional view showing a dielectric heating molding apparatus according to the second embodiment. FIG. 12 is a cross-sectional view showing another dielectric heating molding apparatus according to the second embodiment. FIG. 13 is a cross-sectional view showing a dielectric heating molding apparatus according to the third embodiment. FIG. 14 is a cross-sectional equivalent view of II-II of FIG. 1 showing another dielectric heating molding apparatus according to the third embodiment before depressurizing the inside of the decompression bag. FIG. 15 is a cross-sectional equivalent view of III-III of FIG. 1 showing another dielectric heating molding apparatus after depressurizing the inside of the decompression bag according to the third embodiment.

Preferred embodiments of the dielectric heating molding apparatus and the dielectric heating molding method described above will be described with reference to the drawings.
<Embodiment 1>
As shown in FIGS. 1 to 4, the dielectric heating molding apparatus 1 of the present embodiment includes a molding die 2 and a dielectric heating source 6. The molding die 2 has an insulating property that generates heat due to dielectric loss, and has a cavity 20 in which the molded body 8 is molded from the molding material 80. The dielectric heating source 6 applies an alternating electric field Y to the molding material 80 and the molding die 2 in the cavity 20 by an AC voltage applied between a pair of electrodes 61 arranged on both sides of the molding die 2 to enter the cavity 20. The molding material 80 is heated.

Further, the dielectric heating molding apparatus 1 of the present embodiment also includes a pressure reducing bag 3 and a pressure reducing pump 4. The decompression bag 3 is formed in a bag shape by a flexible sheet material 30, and the molding die 2 is housed inside. The decompression pump 4 decompresses the inside of the decompression bag 3 and the inside of the cavity 20.

First, the dielectric heating molding apparatus 1 will be described in detail.
As shown in FIG. 9, the dielectric heating molding apparatus 1 is used, for example, for producing a small amount of a molded body 8, for molding a molded body 8 having a complicated shape unsuitable for manufacturing a mold, and for forming a large molded body 8. It may be used for molding purposes and the like. The dielectric heating molding apparatus 1 may be used, for example, for molding a molded body 8 used as a vehicle, an electric appliance, various prototypes, or the like. FIG. 9 schematically shows an example of a molded body 8 molded by the dielectric heating molding apparatus 1.

(Molding mold 2)
As shown in FIG. 5, the molding die 2 is made of various materials having insulating properties other than metal. As the molding die 2, various materials having different heating characteristics from the molding material 80 and having the property of being able to release the molded molded body 8 when an alternating electric field Y is applied or the like are used. Be done. The mold 2 is formed of, for example, a rubber mold formed of a rubber material, a resin mold formed of a resin material, a ceramic mold composed of a ceramic material, a cement mold formed of a cement material, or a plaster material. It may be composed of a plaster mold or the like.

Rubber materials include silicone rubber, fluororubber, etc., resin materials include photocurable resins, thermosetting resins, thermoplastic resins, etc., and ceramic materials include oxides, carbides, nitrides, and hoes. There is a molded body 8 (sintered body) of an inorganic compound such as a compound.

The molding die 2 can be molded from a material having a smaller dielectric loss than the molding material 80, a material having a larger dielectric loss than the molding material 80, and the like. The value of the dielectric loss depends on the type of substance as an insulator. Further, the dielectric loss is determined according to the value of the dielectric loss tangent tan δ.

The molding die 2 may be molded by transferring the shape of the master model having the shape of the molded body 8, or may be formed into a three-dimensional shape by a 3D printer or the like. When the molding die 2 is formed by a 3D printer, it is possible to add a process that smoothes the stepped shape due to the lamination, which is left on the molding surface 202 forming the cavity 20.

As shown in FIG. 5, the molding die 2 may be formed by being divided into two divided mold portions 21, or may be formed by being divided into three or more divided mold portions 21. A division surface 204 forming a parting line is formed between the division mold portions 21. As shown in FIG. 5, the molding die 2 may be a fixed mold in which the positions of the plurality of split mold portions 21 are fixed to each other, and as shown in FIG. 10, the positions of the plurality of split mold portions 21 are fixed to each other. It may be a movable type that can be relatively changed to reduce the volume of the cavity 20.

The molding die 2 may be a single mold formed entirely of the same material, or may be a composite mold using partially different materials. The composite mold includes, for example, as shown in FIG. 6, a molding surface layer 211 formed along the molding surface 202 forming the cavity 20, and a general portion 210 as a portion other than the molding surface layer 211 of the molding mold 2. May be formed by. In this case, the molded surface layer 211 is made of a material having a larger dielectric loss than the general portion 210. The molded surface layer 211 contains, for example, at least one substance selected from the group consisting of carbon black, graphite, silicon carbide, ferrite, barium titanate, graphite and manganese dioxide in order to increase the dielectric loss. You may.

The shape of the cavity 20 of the molding die 2, in other words, the shape of the molded body 8 molded by the dielectric heating molding apparatus 1, can be the shape of various resin molded parts used as products. The shape of the cavity 20 may be various, for example, the shape of the body of the vehicle, the shape of various cases, the shape of functional parts, a cylinder, a prism, or the like.

As shown in FIG. 5, the molding die 2 is connected to a cavity 20 which is a space along the shape of the molded body 8 to be molded, and a vacuum drawing when the inside of the cavity 20 is evacuated by connecting to an appropriate position of the cavity 20. A vacuum passage 22 serving as a passage is formed. The decompression path 22 is connected to the cavity 20 and the outer surface 201 of the molding mold 2. The plurality of divided mold portions 21 of the molding mold 2 are divided so that the molded body 8 molded in the cavity 20 can be taken out.

The decompression path 22 may connect the molding surface 202 of the cavity 20 and the outer surface 201 of the molding mold 2 not only at one location but also at a plurality of locations. The decompression path 22 may be formed so as to open to the molding surface 202 of a portion having a large volume in the cavity 20. Further, the decompression path 22 may be formed so as to open at a portion of the molding surface 202 of the cavity 20 where the molding material 80 is difficult to be filled or where gas (residual gas) in the cavity 20 is difficult to escape.

As these sites forming the decompression path 22, for example, as shown in FIG. 1, there is an end portion 203 that becomes a dead end in the cavity 20 and the like. The outer surface 201 of the molding die 2 refers to a surface located outside the molding die 2. In addition to air, the gas in the cavity 20 includes substances that are vaporized from resin or the like and remain in the cavity 20.

When the molding die 2 is made of an elastically deformable rubber material, the molding die 2 may be deformed by receiving a mold clamping force by the pressure reducing bag 3. When the molding die 2 is deformed, the volume of the cavity 20 is reduced, the gas remaining in the cavity 20 is extracted, and the shape of the molded body 8 to be molded in the cavity 20 is adjusted.

As shown in FIG. 10, the plurality of split mold portions 21 constituting the molding mold 2 may be relatively movable so as to reduce the volume of the cavity 20. The cavity 20 is formed between the plurality of split mold portions 21. In a state where the split mold portions 21 are combined to form the cavity 20, the volume of the cavity 20 is reduced when the split mold portions 21 approach each other due to the mold clamping force of the pressure reducing bag 3. On the other hand, when the split mold portions 21 are separated from each other after the molded body 8 is molded, the molded molded body 8 is taken out from the cavity 20.

(Molding material 80)
As shown in FIGS. 1 and 2, the type of the molding material 80 may be a resin such as a thermoplastic resin or a thermosetting resin, or ceramic particles containing a metal compound or the like. The ceramic particles may contain a binder of a resin such as a thermoplastic resin. The form of the molding material 80 may be irregular particles, a solid material having a predetermined shape, a liquid material melted by heating, or the like. Further, the molding materials 80 having the forms of particles, solids, liquids and the like may be used in combination with each other.

When the granular or solid molding material 80 is used, the molding material 80 may be placed in the cavity 20 of the molding mold 2 before the molding mold 2 is placed in the vacuum bag 3. .. Further, the granular or liquid molding material 80 may be put into the cavity 20 of the molding mold 2 arranged in the pressure reducing bag 3. Further, a part of the granular or solid molding material 80 is arranged in the cavity 20 of the molding mold 2 outside the decompression bag 3, and the rest of the granular molding material 80 or the liquid molding material 80 is used. It may be arranged in the cavity 20 of the molding mold 2 arranged in the decompression bag 3.

(Dielectric heating source 6)
As shown in FIGS. 3 and 4, the dielectric heating source 6 alternates with the molding material 80 and the molding die 2 in the cavity 20 by the AC voltage applied between the pair of electrodes 61 arranged on both sides of the molding die 2. An electric field Y is applied. The dielectric heating source 6 uses a high frequency as an electromagnetic wave that generates an alternating electric field Y by a pair of electrodes 61. The frequency of the AC voltage generated by the dielectric heating source 6 is a high frequency as an electromagnetic wave including a wavelength region of 1 m to 100 m.

The dielectric heating molding apparatus 1 is used when the dielectric loss of the molding material 80 is larger than the dielectric loss of the molding die 2 and the pressure reducing bag 3. In this case, for example, it is assumed that a substance for increasing the dielectric property is added to the molding material 80. In this case, a high-frequency AC voltage is applied to a pair of electrodes 61 arranged on both sides of the decompression bag 3 in which the molding die 2 is housed, and a high-frequency AC voltage is applied to the molding material 80, the molding die 2 and the decompression bag 3. When an alternating electric field Y due to voltage is applied, the molding material 80 generates heat due to dielectric loss and is heated.

On the other hand, in the dielectric heating molding apparatus 1, when the molding surface layer 211 having a larger dielectric loss than the molding material 80 and the general portion 210 is formed in the molding die 2, or compared with the dielectric loss of the molding material 80. It is also used when the dielectric loss of the molding die 2 is large. In these cases, the molding material 80 is heated by receiving heat conduction from the molding surface layer 211 or the molding mold 2 that generates heat due to the dielectric loss.

Further, as shown in FIGS. 3 and 4, the pair of electrodes 61 may be used to press the plurality of split mold portions 21 from the outside of the plurality of split mold portions 21 of the molding mold 2. In this case, the pair of electrodes 61 can be used to mold the mold 2 so that the split mold portions 21 do not separate from each other. The pair of electrodes 61 may press the plurality of split mold portions 21 from above the decompression bag 3.

Further, the plurality of split mold portions 21 can be relatively moved or deformed so as to reduce the volume of the cavity 20 by receiving the mold clamping force of the pair of electrodes 61. The plurality of split mold portions 21 of the present embodiment receive the mold clamping force of the pressure reducing bag 3 and the mold clamping force of the pair of electrodes 61. As a result, the mold clamping of the plurality of split mold portions 21 is performed more effectively.

When the pair of electrodes 61 are not used to press the plurality of split mold portions 21, the pair of electrodes 61 are arranged so as to form a gap between the pair of split mold portions 21 or the pressure reducing bag 3. May be done.

Further, in the dielectric heating molding apparatus 1, the inside of the cavity 20 may be directly depressurized by the decompression pump 4 without using the decompression bag 3. Further, the plurality of split mold portions 21 may be molded by the pair of electrodes 61 without using the pressure reducing bag 3 and the pressure reducing pump 4.

The outer shape of the electrode 61 of this embodiment is larger than the outer shape of the molding die 2, and the entire molding die 2 is arranged between the pair of electrodes 61. Then, the positional relationship between the pair of electrodes 61 and the molding die 2 is fixed. On the other hand, when the outer shape of the electrode 61 is smaller than the outer shape of the molding die 2, a part of the molding die 2 may be arranged between the pair of electrodes 61. In this case, the molding die 2 can be moved relative to the pair of electrodes 61 to sequentially melt the molding material 80 located in each portion of the cavity 20 of the molding die 2.

(Decompression pump 4)
As shown in FIG. 1, the decompression pump 4 is also called a vacuum pump, and evacuates the inside of the decompression bag 3 and the cavity 20 of the molding mold 2. The pressure reducing pump 4 sucks out the gas (residual gas) in the pressure reducing bag 3 to bring the inside of the pressure reducing bag 3 and the cavity 20 of the molding mold 2 into a reduced pressure state (vacuum state) lower than the atmospheric pressure.

When the gas in the decompression bag 3 is sucked out, the decompression bag 3 bends and deflate, so that pressure acts from the decompression bag 3 to the molding die 2 and the plurality of split mold portions 21 of the molding die 2 move relatively. Is prevented. Then, the mold 2 is molded by the pressure reducing bag 3. Further, the inside of the cavity 20 of the molding die 2 is also in a reduced pressure state so that no gas remains in the cavity 20 and no cavity, chipping or the like is formed in the molded body 8 molded in the cavity 20.

(Decompression pipe 5)
As shown in FIG. 1, the dielectric heating molding apparatus 1 of the present embodiment includes a pressure reducing pipe 5 for reducing the pressure inside the pressure reducing bag 3 by the pressure reducing pump 4. The decompression pipe 5 is connected to a decompression path 22 of the molding mold 2 arranged inside the decompression bag 3 and a decompression pump 4 arranged outside the decompression bag 3. A part of the decompression pipe 5 is arranged inside the decompression bag 3, and the rest of the decompression pipe 5 is arranged outside the decompression bag 3. The decompression pipe 5 is used by the decompression pump 4 to evacuate the vacuum bag 3 and the cavity 20 of the molding mold 2. In other words, the decompression pipe 5 of the present embodiment has a configuration in which both the inside of the cavity 20 of the molding mold 2 and the inside of the decompression bag 3 are depressurized.

The tip portion 51 of the pressure reducing pipe 5 is configured to be mounted on the mounting portion 23 formed at the forming portion of the pressure reducing path 22 on the outer surface 201 of the molding die 2. The tip portion 51 of the pressure reducing pipe 5 and the mounting portion 23 of the molding die 2 are formed in a shape that can be repeatedly attached and detached. The pressure reducing pipe 5 may be provided with a valve 53, which will be described later, capable of opening and closing the flow path 50. The decompression pipe 5 of the present embodiment has a flexible piping portion 54 at a portion connected to the decompression pump 4.

(Decompression bag 3)
As shown in FIGS. 7 and 8, the sheet material 30 constituting the decompression bag 3 is formed of a flexible silicone film. The silicone film is also called a silicone sheet, a silicone rubber film, a silicone rubber sheet, or the like. A transparent or translucent silicone film can be used for the sheet material 30. In this case, transparent or translucent silicone rubber can be used for the molding mold 2. Then, the molding state of the molding material 80 in the cavity 20 can be confirmed by looking through the pressure reducing bag 3 and the molding mold 2 from the outside of the pressure reducing bag 3.

The pressure reducing bag 3 may be made of a molding material 80 or a material having a smaller dielectric loss than the molding mold 2. Further, when the molding die 2 on which the molding surface layer 211 is formed is used, the pressure reducing bag 3 has a material that is more likely to transmit near infrared rays than the molding surface layer 211, or has a dielectric loss as compared with the molding surface layer 211. It may be composed of a small material.

It is preferable that the sheet material 30 constituting the decompression bag 3 has not only flexibility but also elasticity. Since the sheet material 30 also has elasticity, the pressure reducing bag 3 can be more easily adhered to the molding die 2. Further, it is preferable that the sheet material 30 has non-adhesiveness or releasability and can be easily separated from the molding mold 2 and the like.

In addition to the silicone film, the sheet material 30 may be made of various rubber films having flexibility and elasticity. Further, the sheet material 30 may be made of a resin film having at least flexibility. It is preferable to use a material having excellent heat resistance for the sheet material 30. The sheet material 30 may be made of, for example, a fluororubber film, a fluororesin film, a polymethylpentene film, or the like.

The decompression bag 3 may be formed by adhering an appropriate portion of one folded sheet material 30 with an adhesive. Further, the decompression bag 3 may be formed by adhering two sheet materials 30 with an adhesive. When the pressure reducing bag 3 is formed by using the resin sheet material 30, the pressure reducing bag 3 may be formed by melting and joining the sheet material 30.

The pressure reducing bag 3 is formed in a size that can accommodate at least the entire molding mold 2. The decompression bag 3 has an opening 31 for allowing the molding die 2 to be taken in and out, and an opening chuck 32 for closing the opening 31 and sealing the inside of the decompression bag 3. Further, the pressure reducing bag 3 is formed with an insertion port 33 into which the pressure reducing pipe 5 is inserted, and the peripheral edge of the insertion port 33 is sealed with a sealing material.

As shown in FIG. 8, the opening 31 is formed on one side of the pressure reducing bag 3 formed in a quadrangle shape. The opening chuck 32 sandwiches and seals a pair of ends of the sheet material 30 forming the opening 31 in the pressure reducing bag 3. The opening chuck 32 is formed by a combination of a female side chuck portion 321 in which a groove is formed and a male side chuck portion 322 in which a convex portion fitted in the groove is formed.

Further, when the molding die 2 becomes large, the pressure reducing bag 3 is formed by arranging a pair of sheet materials 30 on both sides of the molding die 2 and the pressure reducing pipe 5 and then closing the peripheral edges of the pair of sheet materials 30. You may. In other words, after the molding die 2 and the pressure reducing pipe 5 are arranged between the pair of sheet materials 30, the peripheral edges of the pair of sheet materials 30 are closed by a sealing zipper or the like, and the molding die 2 and the pressure reducing pipe 5 are closed. A part of the decompression bag 3 may be formed inside.

(Ventilation hole 52 of decompression bag 3 and decompression pipe 5)
As shown in FIG. 7, the decompression bag 3 is also called a vacuum pack, and can maintain the inside of the decompression bag 3 in a decompression state (vacuum state) lower than the atmospheric pressure. The pressure reducing bag 3 has a function of molding the molding die 2 and a function of maintaining the inside of the cavity 20 of the molding die 2 in a reduced pressure state.

As shown in FIGS. 1, 3 and 7, the decompression pipe 5 of the present embodiment has a ventilation hole 52 for decompressing the inside of the decompression bag 3. The ventilation hole 52 is formed on the side surface of the portion of the pressure reducing pipe 5 that is arranged in the pressure reducing bag 3. In the pressure reducing pipe 5, the inside of the cavity 20 of the molding mold 2 can be evacuated from the tip opening 511 of the tip portion 51, and the inside of the pressure reducing bag 3 can be evacuated from the ventilation hole 52. The tip opening 511 and the ventilation hole 52 of the tip 51 of the decompression pipe 5 serve as suction ports for evacuating by the decompression pump 4.

When the decompression pump 4 is used to evacuate the inside of the decompression bag 3, the decompression pipe 5 is evacuated from the tip opening 511 of the tip 51, and at the same time, the decompression bag 3 is evacuated from the ventilation hole 52 of the decompression pipe 5. The inside is evacuated. At this time, the distance between the decompression pump 4 and the ventilation hole 52 of the decompression pipe 5 is shorter than the distance between the decompression pump 4 and the tip opening 511 of the tip portion 51 of the decompression pipe 5, and the gap in the decompression bag 3 is in the cavity 20. The flow rate of the gas sucked from the ventilation hole 52 is larger than the flow rate of the gas sucked from the tip opening 511 because it is larger than the gap of. Then, the speed at which the pressure inside the pressure reducing bag 3 is depressurized becomes faster than the speed at which the inside of the cavity 20 is depressurized, and the degassing inside the pressure reducing bag 3 is stopped before the degassing inside the cavity 20.

Further, as shown in FIGS. 3 and 4, as the gas in the decompression bag 3 runs out, the sheet material 30 of the decompression bag 3 comes into close contact with the decompression pipe 5 and the mold 2. The ventilation hole 52 is closed by the sheet material 30 of the decompression bag 3 in the process of running out of gas in the decompression bag 3 or when the gas in the decompression bag 3 is almost exhausted. When the ventilation hole 52 is closed, the only portion where the vacuum is drawn by the decompression pump 4 is the tip opening 511 of the tip 51 of the decompression pipe 5, and the gas in the cavity 20 is sucked from the tip opening 511. In this way, the decompression bag 3 compacts the molding die 2 and appropriately sucks the gas in the cavity 20.

By using the ventilation hole 52 formed on the side surface of the decompression pipe 5 as a suction port for evacuating, the inside of the decompression bag 3 and the inside of the cavity 20 are effectively decompressed by an extremely simple structure. can do. Then, the degree of vacuum in the cavity 20 can be increased.

In the dielectric heating molding apparatus 1, the pressure reducing pipe 5 connected to the pressure reducing pump 4 is branched into two branch pipes, the first branch pipe is connected to the pressure reducing path 22 of the molding mold 2, and the second branch is made. A configuration may be adopted in which the pipe is connected to the decompression bag 3.

As shown in FIGS. 1 and 7, the ventilation holes 52 may be formed at one location on the side surface of the portion arranged in the pressure reducing bag 3 in the pressure reducing pipe 5, or may be formed at a plurality of locations. The ventilation hole 52 is formed at a position where the molding die 2 is arranged in the decompression bag 3 and is not closed by the molding die 2 and is not immediately closed by the decompression bag 3. The ventilation holes 52 are preferably formed on the side surface of the portion of the decompression pipe 5 that is arranged in the decompression bag 3 except for the portion of the decompression pipe 5 that faces the sheet material 30 that constitutes the decompression bag 3. Specifically, the ventilation holes 52 are formed, for example, in the direction parallel to the sheet material 30 or in the direction inclined with respect to the sheet material 30 on the side surface of the portion of the pressure reducing pipe 5 arranged in the pressure reducing bag 3. be able to.

The decompression pipe 5 may be detachable from the decompression pump 4. In this case, as shown in FIGS. 1 and 7, the decompression pipe 5 is provided with a valve 53 for maintaining the decompression state in the decompression bag 3 when the decompression pipe 5 is removed from the decompression pump 4. It is preferable to provide it. The mold 2, the decompression bag 3, the decompression pipe 5, and the valve 53 can be treated as one set separated from the decompression pump 4. As the valve 53, a ball valve, a needle valve, or the like that is opened and closed by a manual operation by an operator is used.

When the pressure reducing pipe 5 is removed from the pressure reducing pump 4, the valve 53 closes the flow path 50 of the pressure reducing pipe 5 to maintain the pressure in the pressure reducing bag 3. When the flow path 50 of the decompression pipe 5 is closed by the valve 53 while the inside of the decompression bag 3 is depressurized, the state in which the decompression bag 3 is in close contact with the mold 2 and the decompression pipe 5 is maintained, and the mold is fixed to the mold 2. The state in which the force acts is maintained.

By removing the pressure reducing pipe 5 arranged in the pressure reducing bag 3 and the molding mold 2 from the pressure reducing pump 4, the molding material 80 in the molding mold 2 is cooled and solidified after the molding body 8 is molded. In addition, the decompression pump 4 can be used for molding another molded body 8 in which another depressurizing bag 3, a molding die 2 and a depressurizing pipe 5 are used. Then, the molding die 2 arranged in the decompression bag 3 can be moved to an arbitrary cooling place. In addition, a place and time for cooling the molding die 2 and the molding material 80 can be easily secured.

(Dielectric heating molding method)
Next, the dielectric heating molding method using the dielectric heating molding apparatus 1 will be described in detail.
In the dielectric heating molding method, a placement step, a depressurizing step, a heating step, and a cooling step are performed to mold the molded body 8 from the molding material 80.

(Placement process)
In the arranging step, as shown in FIGS. 2 and 7, a molding mold in which the molding material 80 is arranged in the cavity 20 in the decompression bag 3 formed in a bag shape by the flexible sheet material 30. 2 is placed. As the molding die 2, a mold having a property of generating heat due to dielectric loss is used.

When the particulate molding material 80 is used, a plurality of split mold portions 21 may be combined with each other after the molding material 80 is arranged in the recess forming the cavity 20. Further, the particle-shaped molding material 80 may be charged into the cavity 20 formed by the divided mold portions 21 combined with each other from the decompression path 22 or the charging port (not shown) formed in the split mold portion 21. Further, a part of the molding material 80 may be put into the cavity 20 of the molding die 2 arranged in the decompression bag 3 from the outside of the decompression bag 3.

As shown in FIGS. 2 and 7, in the arrangement step, the decompression pipe 5 is connected to the decompression pump 4, a part of the decompression pipe 5 is arranged in the decompression bag 3, and the decompression pipe 5 in the decompression bag 3 is provided. A state in which the insertion port 33 of the above is sealed is formed. Then, the molding die 2 in which the molding material 80 is arranged is inserted into the pressure reducing bag 3 through the opening 31 of the pressure reducing bag 3, and the mounting portion 23 of the molding die 2 is mounted on the tip portion 51 of the pressure reducing pipe 5. To. Since the pressure reducing bag 3 has flexibility, it can be arbitrarily deformed according to the size and shape of the molding die 2. After the mold 2 is arranged in the decompression bag 3, the opening 31 of the decompression bag 3 is closed by the opening chuck 32. As a result, the inside of the pressure reducing bag 3 in which the molding die 2 is arranged is sealed.

(Decompression process)
As shown in FIGS. 3 and 4, in the depressurizing step, the inside of the depressurizing bag 3 and the inside of the cavity 20 are depressurized, the depressurizing bag 3 is in close contact with the molding die 2, and the mold clamping force by the depressurizing bag 3 is applied to the molding die 2. It works. In the depressurizing step, the gas in the decompression bag 3 and the gas in the cavity 20 of the molding mold 2 are sucked by the decompression pump 4 through the decompression pipe 5. At this time, the gas in the pressure reducing bag 3 is sucked from the ventilation hole 52 of the pressure reducing pipe 5, and the gas in the cavity 20 is sucked from the tip opening 511 of the tip portion 51 of the pressure reducing pipe 5. Then, the ventilation hole 52 is closed by the decompression bag 3, the degassing in the decompression bag 3 is stopped, and then the degassing in the cavity 20 is continued.

More specifically, after the decompression by the decompression pump 4 is started due to a large pressure loss in the cavity 20, the gas in the cavity 20 is sucked while the ventilation hole 52 is not closed. Hateful. In other words, the decompression pump 4 allows the gas in the decompression bag 3 from the vent 52 of the decompression pipe 5 to be compared with the suction force of the gas in the cavity 20 from the tip opening 511 of the tip 51 of the decompression pipe 5. The suction power becomes stronger. However, when the gas in the pressure reducing bag 3 is sucked from the ventilation hole 52 of the pressure reducing pipe 5, the gas in the cavity 20 is also sucked from the tip opening 511 of the tip portion 51 of the pressure reducing pipe 5.

When the inside of the decompression bag 3 is depressurized and the decompression bag 3 is deflated, the sheet material 30 of the decompression bag 3 comes into close contact with the decompression pipe 5 and the mold 2. Then, as shown in FIGS. 3 and 4, when the entire ventilation hole 52 is closed by the sheet material 30 in the process of shrinking the pressure reducing bag 3, only the tip opening 511 of the tip portion 51 of the pressure reducing pipe 5 is opened. In this state, the inside of the cavity 20 is depressurized from the tip opening 511 of the tip 51 of the pressure reducing pipe 5.

(Heating process)
In the heating step, at least one of the molding material 80 and the molding mold 2 in the cavity 20 is heated, and the molding material 80 in the cavity 20 is melted. In the heating step, a dielectric heating source 6 for applying a high frequency AC voltage between the pair of electrodes 61 is used. Then, a high-frequency alternating electric field Y is applied to the molding die 2 from the pair of electrodes 61, the molding die 2 generates heat due to the dielectric loss due to the alternating electric field Y, and the molding material in the cavity 20 is transferred by the heat transfer from the molding die 2. 80 is heated.

When the molding surface layer 211 is formed on the molding mold 2, the molding surface layer 211 is heated by the alternating electric field Y, and the molding material 80 in the cavity 20 is heated by the heat transfer from the molding surface layer 211. May be good.

In the heating step, it is preferable to continue evacuation by the decompression pump 4 so that the mold clamping force continuously acts from the decompression bag 3 to the molding die 2. As shown in FIG. 10, when the molding die 2 capable of reducing the volume of the cavity 20 is used, when the molding material 80 in the cavity 20 is melted in the heating step, the molding material 80 in the cavity 20 is subjected to the mold clamping force by the pressure reducing bag 3. , The plurality of split mold portions 21 constituting the molding mold 2 come close to each other. Further, when the elastically deformable molding die 2 is used, when the molding material 80 in the cavity 20 melts, the molding die 2 is deformed by the mold clamping force of the pressure reducing bag 3 to deform the volume of the cavity 20. May be reduced.

(Cooling process)
In the cooling step, the molten molding material 80 in the cavity 20 is cooled and solidified in a state where the mold clamping force acts on the molding mold 2, and the molded product 8 is obtained. In the cooling step, the heat remaining in the decompression bag 3, the molding die 2 and the molding material 80 may be dissipated by natural convection of air, or may be dissipated by forced convection of air by a fan or the like.

In the cooling step, the mold 2 may be left in a state where the pressure reducing bag 3 and the pressure reducing pipe 5 arranged in the molding mold 2 are removed from the pressure reducing pump 4. At this time, the valve 53 provided in the decompression pipe 5 is closed, and the decompression pump 4 is removed from the decompression pipe 5 while the decompression state in the flow path 50 of the decompression pipe 5 and the decompression bag 3 is maintained. ..

In the heating step and the cooling step, the pair of electrodes 61 may be used to press the plurality of split mold portions 21 from the outside of the plurality of split mold portions 21 of the molding mold 2. Then, the mold clamping force of the pressure reducing bag 3 and the mold clamping force of the pair of electrodes 61 can be applied to the molding die 2.

When the molding material 80 in the cavity 20 of the molding die 2 is cooled and solidified, the opening chuck 32 is removed from the opening 31 of the decompression bag 3, and the molding die 2 is taken out from the opening 31. Then, the plurality of divided mold portions 21 of the molding mold 2 are separated from each other, and the molded body 8 after molding is taken out from between the divided mold portions 21.

(Action effect)
The dielectric heating molding apparatus 1 of the present embodiment makes it possible to mold a molded body 8 having a large size, a complicated shape, or the like by using a dielectric heating source 6 having a pair of electrodes 61.

When molding the molded body 8, a molding die 2 in which the molding material 80 is arranged in the cavity 20 is arranged between the pair of electrodes 61 in the dielectric heating source 6. Further, the molding die 2 is arranged in the decompression bag 3, and the decompression pump 4 decompresses the inside of the decompression bag 3 and the inside of the cavity 20. Next, when an AC voltage is applied between the pair of electrodes 61, an alternating electric field Y is applied to the molding material 80 and the molding mold 2 in the cavity 20. Then, the molding material 80 in the cavity 20 generates heat due to the dielectric loss, or the molding material 80 in the cavity 20 is heated by heat transfer from the molding mold 2 that generates heat due to the dielectric loss, so that the molding material 80 is heated. Melt. After that, the molding material 80 is cooled and solidified to obtain a molded product 8.

In the dielectric heating molding apparatus 1, all or a part of the molding die 2 is arranged between the pair of electrodes 61. The alternating electric field Y is a cavity 20 located in the whole or part of the molding die 2 arranged between the pair of electrodes 61 and in the whole or part of the molding die 2 arranged between the pair of electrodes 61. It is applied to the molding material 80 inside. When the molding die 2 generates heat by using the alternating electric field Y generated by the high frequency AC voltage, the molding die 2 generates heat to a deeper position than when the molding die 2 generates heat by using microwaves. Becomes possible.

Further, when a high-frequency AC voltage is used, it is considered that the molding material 80 in the cavity 20 is more likely to generate heat due to the alternating electric field Y than when microwaves are used. For these reasons, even if the molded body 8 to be molded in the cavity 20 is large or has a complicated shape, the portion of the molding material 80 arranged between the pair of electrodes 61 is , The alternating electric field Y applied to this portion can be more appropriately melted, and the molded body 8 can be appropriately molded.

Therefore, according to the dielectric heating molding apparatus 1 and the dielectric heating molding method of the present embodiment, it is possible to increase the degree of freedom in the size, shape, etc. of the molded body 8 to be molded.

<Embodiment 2>
This embodiment shows the dielectric heating molding apparatus 1 when the dielectric heating source 6 and another heating source are used in combination.
As shown in FIG. 11, the other heating source may be a heater 62 provided on at least one of the pair of electrodes 61 in the dielectric heating source 6 that generates heat by energization. The heater 62 can be provided in each electrode 61, and can be embedded in each of the plurality of arrangement holes 611 formed in each electrode 61. When the heater 62 is used, the molding material 80 in the cavity 20 can be heated by the heater 62 at the same time or alternately with the heating by the dielectric heating source 6, or before and after the heating by the dielectric heating source 6. In this case, it is possible to suppress a partial bias in the heating temperature of the molding material 80 so that the entire molding material 80 is heated as uniformly as possible.

Further, as shown in FIG. 12, the other heating source may be a warm air heating source 7 that heats the mold 2 with the warm air H via the decompression bag 3. The hot air heating source 7 is composed of a heater 71 that heats a gas and a fan 72 that blows the gas heated by the heater 71 into the mold 2 as hot air H. When the hot air heating source 7 is used, the molding material 80 in the cavity 20 is heated by the warm air heating source 7 at the same time or alternately with the heating by the dielectric heating source 6, or before and after the heating by the dielectric heating source 6. It can be performed. Also in this case, it is possible to suppress a partial bias in the heating temperature of the molding material 80 so that the entire molding material 80 is heated as uniformly as possible.

Further, the hot air heating source 7 may be configured such that the molding die 2 housed in the decompression bag 3 is arranged in a warm air environment in which warm air due to natural convection flows without using a fan 72.

The other configurations, effects, and the like of the dielectric heating molding apparatus 1 and the dielectric heating molding method of the present embodiment are the same as those of the first embodiment. Further, also in this embodiment, the components indicated by the same reference numerals as those shown in the first embodiment are the same as those in the first embodiment.

<Embodiment 3>
This embodiment shows various embodiments of the dielectric heating molding apparatus 1 different from the first and second embodiments.
As shown in FIG. 13, a cooling flow path 63 through which the cooling water C flows may be formed in at least one of the pair of electrodes 61 in the dielectric heating source 6. The cooling flow path 63 can be formed by holes formed so as to pass through each electrode 61. Although not shown, a circulation pump for circulating cooling water C is connected to the cooling flow path 63.

In this case, the dielectric heating source 6 also has a function of cooling the mold 2 via the pressure reducing bag 3 by the electrode 61 cooled by the cooling water C flowing through the cooling flow path 63. In this case, in the cooling step of the dielectric heating molding method, the molding die 2 can be forcibly cooled by the electrode 61 cooled by the cooling water C flowing through the cooling flow path 63. Therefore, the molten molding material 80 can be rapidly solidified in the cavity 20 of the molding die 2 by a simple structure in which the cooling flow path 63 is formed in the electrode 61.

Further, as shown in FIGS. 14 and 15, in order to more appropriately apply the mold clamping force from the pressure reducing bag 3 to the mold 2 on both sides of the mold 2, the mold clamping members 25 which are harder than the mold 2 are 25. May be placed. In this case, by using the mold clamping member 25, the mold clamping force can be applied as uniformly as possible to both the thin portion and the thick portion of the molding die 2. The pair of electrodes 61 in the dielectric heating source 6 may or may not press the mold clamping member 25.

Further, the forming portions of the decompression path 22 communicating with the cavity 20 may be formed at a plurality of locations on the outer surface 201 of the molding die 2. In this case, when the inside of the decompression bag 3 is evacuated, the inside of the cavity 20 can be evacuated from a plurality of decompression paths 22. In particular, as shown in FIG. 1, the plurality of decompression paths 22 may be formed at positions communicating with the end portion 203 that becomes a dead end in the cavity 20.

The other configurations, effects, and the like of the dielectric heating molding apparatus 1 and the dielectric heating molding method of the present embodiment are the same as those of the first embodiment. Further, also in this embodiment, the components indicated by the same reference numerals as those shown in the first embodiment are the same as those in the first embodiment.

The present invention is not limited to each embodiment, and further different embodiments can be configured without departing from the gist thereof. The present invention also includes various modifications, modifications within an equal range, and the like. Further, the technical idea of the present invention also includes combinations, forms, etc. of various components assumed from the present invention.

1 Dielectric heating molding device 2 Molding mold 20 Cavity 201 Outer surface 202 Molding surface 21 Divided mold part 210 General part 211 Molding surface layer 22 Decompression path 23 Mounting part 25 Molding member 3 Decompression bag 30 Sheet material 31 Opening 32 Opening chuck 321 Female side chuck part 322 Male side chuck part 33 Insertion port 4 Decompression pump 5 Decompression piping 51 Tip part 511 Tip opening 52 Vent hole 53 Valve 6 Dielectric heating source 61 Electrode 62 Heater 63 Cooling flow path 7 Warm air heating source 71 Heater 72 Fan 8 Molded body 80 Molding material Y Alternating electric field

Claims (12)

An insulating molding die that has a cavity in which a molded product is molded from a molding material and has the property of generating heat due to dielectric loss.
A dielectric heating source that applies an alternating electric field to the molding material in the cavity and the molding mold by an AC voltage applied between a pair of electrodes arranged on both sides of the molding mold to heat the molding material in the cavity. And, a dielectric heating molding apparatus. The molding die is divided into a plurality of split mold portions,
The dielectric heating molding apparatus according to claim 1, wherein the plurality of split mold portions can be relatively moved or deformed so as to reduce the volume of the cavity by receiving a mold clamping force by the pair of electrodes. At least one of the pair of electrodes is provided with a heater that generates heat when energized.
The dielectric heating molding apparatus according to claim 1 or 2, wherein the heating of the molding material in the cavity is performed by the heater at the same time or alternately with the heating by the dielectric heating source, or before and after the heating by the dielectric heating source. .. The dielectric heating molding apparatus further includes a hot air heating source for heating the molding die with warm air.
The dielectric according to claim 1 or 2, wherein the molding material in the cavity is heated by the warm air heating source at the same time or alternately with the heating by the dielectric heating source, or before and after the heating by the dielectric heating source. Heat molding equipment. A cooling flow path through which cooling water flows is formed in at least one of the pair of electrodes.
The dielectric heating molding apparatus according to any one of claims 1 to 4, wherein the dielectric heating source also has a function of cooling the molding mold by the electrodes cooled by the cooling water flowing through the cooling flow path. The molding mold is formed with a decompression path connecting the cavity and the outer surface.
The dielectric heating molding apparatus is
A decompression bag formed in a bag shape by a flexible sheet material and accommodating the molding mold inside.
The dielectric heating molding apparatus according to any one of claims 1 to 5, further comprising a decompression pump that depressurizes the inside of the decompression bag and depressurizes the inside of the cavity through the decompression path. A placement step in which the molding material is placed in an insulating molding cavity that has the property of generating heat due to dielectric loss.
A dielectric heating source is used, and an alternating electric field is applied to the molding material in the cavity and the molding die by an AC voltage applied between a pair of electrodes of the dielectric heating source arranged on both sides of the molding die. A heating step in which the molding material in the cavity is heated, and
A dielectric heating molding method comprising a cooling step of cooling the molding die and the molding material to obtain a molded product from the molding material. The molding die is divided into a plurality of split mold portions,
The dielectric heating molding according to claim 7, wherein in the heating step, the plurality of split mold portions are relatively moved or deformed so as to reduce the volume of the cavity by receiving a mold clamping force by the pair of the electrodes. Method. At least one of the pair of electrodes is provided with a heater that generates heat when energized.
According to claim 7 or 8, in the heating step, the molding material in the cavity is heated by the heater at the same time or alternately with the heating by the dielectric heating source, or before and after the heating by the dielectric heating source. The method according to the dielectric heating molding method. In the heating step, a hot air heating source for heating the mold with warm air is further used, and the hot air is simultaneously or alternately heated by the dielectric heating source, or before and after heating by the dielectric heating source. The dielectric heating molding method according to claim 7 or 8, wherein the molding material in the cavity is heated by a heating source. A cooling flow path through which cooling water flows is formed in at least one of the pair of electrodes.
The dielectric heating molding method according to any one of claims 7 to 10, wherein in the cooling step, the molding mold is cooled by the electrodes cooled by the cooling water flowing through the cooling flow path. The molding mold is formed with a decompression path connecting the cavity and the outer surface.
In the arranging step, a decompression bag formed in a bag shape by a flexible sheet material and accommodating the molding mold inside is used, and the molding material is placed in the cavity in the decompression bag. The placed mold is placed and
After the arrangement step, the inside of the decompression bag and the inside of the cavity via the decompression path are depressurized by the decompression pump, the decompression bag is brought into close contact with the molding die, and the molding force by the decompression bag is applied to the molding die. A decompression process is performed that acts on
The dielectric heating molding method according to any one of claims 7 to 11, wherein in the cooling step, a state in which the mold clamping force acts on the molding mold is maintained.

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