JP7175507B2 - Dielectric heating molding apparatus and dielectric heating molding method - Google Patents

Description

The present invention relates to a dielectric thermoforming apparatus and a dielectric thermoforming method.

Methods for molding resin moldings such as thermoplastic resins include injection molding, blow molding, press molding, and the like. In these molding methods, a metal mold is used. When manufacturing a mold, it is necessary to cut the metal material three-dimensionally, and this cutting process is time-consuming. On the other hand, as a molding method that enables molding of a thermoplastic resin without using a molding die, there is a lamination molding method known as a 3D printer or the like. In the layered manufacturing method, although a molding die is not required, there is a weak point in characteristics due to the layer interface remaining in the molded resin molded product. As a molding method overcoming the weaknesses of these molding methods, for example, there is a method of molding a thermoplastic resin using a molding die made of a non-metallic material and electromagnetic waves, which is disclosed in Patent Documents 1 and 2.

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

Further, in the method for molding a thermoplastic resin molded product of Patent Document 2, when the thermoplastic resin in the rubber mold is heated by electromagnetic waves, the pressure inside the rubber mold is made lower than the external pressure by a vacuum means, A pair of rubber mold parts constituting a rubber mold are brought close to each other, and a thermoplastic resin molded product is molded in the rubber mold with a reduced volume.

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

In the thermoplastic resin molding methods disclosed in Patent Documents 1 and 2, etc., electromagnetic waves such as near-infrared rays and microwaves are used. is heated. Therefore, it has been found that, for example, when molding a large-sized molded body, a molded body having a complicated shape, or the like, it is difficult for the electromagnetic wave to irradiate the entire molding material in the cavity. Therefore, it is particularly desired to develop a molding die made of a non-metallic material and a heating method using electromagnetic waves, which are effective for molding large-sized moldings, moldings having complicated shapes, and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and was obtained to provide a dielectric heating molding apparatus and a dielectric heating molding method that can increase the degree of freedom in the size, shape, etc. of a molded body to be molded. .

One of the first aspects of the present invention is
an insulating mold having a cavity in which a molded body is molded from a molding material and having a property of generating heat due to dielectric loss;
A dielectric heating source that heats the molding material in the cavity by applying an alternating electric field to the molding material in the cavity and the molding die by an alternating voltage applied between a pair of electrodes arranged on both sides of the molding die. and
The mold is divided into a plurality of divided mold parts,
In the dielectric heating molding apparatus, the plurality of split mold parts are capable of relative movement or deformation so as to reduce the volume of the cavity under the clamping force of the pair of electrodes .
Another aspect of the first aspect of the present invention is
an insulating mold having a cavity in which a molded body is molded from a molding material and having a property of generating heat due to dielectric loss;
A dielectric heating source that heats the molding material in the cavity by applying an alternating electric field to the molding material in the cavity and the molding die by an alternating voltage applied between a pair of electrodes arranged on both sides of the molding die. and
A cooling channel through which cooling water flows is formed in at least one of the pair of electrodes,
The dielectric heating source is in a dielectric heating molding apparatus that also has a function of cooling the molding die by the electrode cooled by the cooling water flowing through the cooling channel.

A second aspect of the present invention is
a placement step in which the molding material is placed in a cavity of an insulating mold having a 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 mold by an alternating voltage applied between a pair of electrodes of the dielectric heating source located on opposite sides of the mold. a heating step in which the molding material in the cavity is heated;
a cooling step of cooling the mold and the molding material to obtain a molded body from the molding material.

(Dielectric heating molding apparatus of the first aspect)
The dielectric heating molding apparatus uses a dielectric heating source having a pair of electrodes to enable molding of large-sized, complicated-shaped molded bodies, and the like.

When molding a molded body, a molding die having a molding material disposed in a cavity is placed between a pair of electrodes in a dielectric heating source. Then, when an alternating voltage is applied between the pair of electrodes, an alternating electric field is applied to the molding material and mold inside the cavity. Then, the molding material in the cavity heats up due to dielectric loss, or the molding material in the cavity is heated by heat transfer from the mold that heats up due to dielectric loss, and the molding material melts. After that, the molding material is cooled and solidified to obtain a molded body.

In the dielectric heating molding apparatus, all or part of the mold is placed between a pair of electrodes. The alternating electric field is applied to all or part of the mold placed between the pair of electrodes and to the molding material in the cavity located in all or part of the mold placed between the pair of electrodes. applied. When the molding die generates heat using an alternating electric field generated by an AC voltage, heat can be generated at a deeper position in the molding die than when the molding die generates heat 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 placed between the pair of electrodes is applied to this portion. It can be melted more appropriately by the alternating electric field, and the compact can be molded appropriately.

In the case where a part of the mold is arranged between the pair of electrodes, the mold is moved relative to the pair of electrodes, and the molding material positioned at each part in the cavity of the mold is removed. can be melted sequentially.

Therefore, according to the dielectric heating molding apparatus, the degree of freedom of the size, shape, etc. of the molding to be molded can be increased.

(Dielectric heating molding method of the second aspect)
In the dielectric thermoforming method, a placement step, a heating step, and a cooling step are performed to form a molded body from the molding material. In particular, the heating step uses a dielectric heating source to better melt the portion of the molding material located between the pair of electrodes.

Therefore, according to the dielectric heating molding method, as in the case of the dielectric heating molding apparatus, the degree of freedom of the size, shape, etc. of the molded body to be molded can be increased.

FIG. 1 is a sectional view showing a dielectric thermoforming apparatus according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, showing the dielectric thermoforming apparatus before reducing the pressure in the vacuum bag according to the first embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1, showing the dielectric thermoforming apparatus after depressurization in the decompression bag according to the first embodiment; 4 is a cross-sectional view taken along line IV-IV of FIG. 1, showing the dielectric thermoforming apparatus after depressurization in the decompression bag according to the first embodiment; FIG. 5 is a cross-sectional perspective view showing a mold divided into a plurality of split mold parts according to the first embodiment. FIG. 6 is a cross-sectional view showing another mold according to the first embodiment. FIG. FIG. 7 is a perspective view showing the dielectric thermoforming apparatus with the vacuum bag opened according to the first embodiment. 8 is a perspective cross-sectional view showing an enlarged periphery of an opening chuck that closes the opening of the decompression bag according to the first embodiment; FIG. 9 is a perspective cross-sectional view showing an example of a molded body according to Embodiment 1. FIG. 10 is a cross-sectional view showing another dielectric heating molding apparatus according to the first embodiment; FIG. FIG. 11 is a cross-sectional view showing a dielectric thermoforming apparatus according to Embodiment 2. FIG. 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 thermoforming apparatus according to Embodiment 3. FIG. FIG. 14 is a cross-sectional view corresponding to II-II in FIG. 1, showing another dielectric heating molding apparatus before reducing the pressure in the vacuum bag according to the third embodiment. FIG. 15 is a cross-sectional view corresponding to III-III in FIG. 1, showing another dielectric heating molding apparatus after reducing the pressure in the vacuum bag according to the third embodiment.

Preferred embodiments of the above-described dielectric heat molding apparatus and dielectric heat molding method will be described with reference to the drawings.
<Embodiment 1>
A dielectric heating molding apparatus 1 of this embodiment includes a molding die 2 and a dielectric heating source 6, as shown in FIGS. The molding die 2 is insulative and has the property of generating 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 in the cavity 20 and the molding die 2 by an AC voltage applied between a pair of electrodes 61 arranged on both sides of the molding die 2 to heat the inside of the cavity 20. The molding material 80 is heated.

The dielectric thermoforming apparatus 1 of this embodiment also includes a vacuum bag 3 and a vacuum pump 4 . The decompression bag 3 is formed in a bag shape from a sheet material 30 having flexibility, and the mold 2 is accommodated therein. The decompression pump 4 decompresses the interior of the decompression bag 3 and the interior of the cavity 20 .

First, the dielectric thermoforming apparatus 1 will be described in detail.
As shown in FIG. 9, the dielectric heating molding apparatus 1 can be used, for example, for small-lot production of molded bodies 8, for molding molded bodies 8 having complex shapes unsuitable for manufacturing molds, and for molding large-sized molded bodies 8. It may be used for purposes such as molding. The dielectric heating molding apparatus 1 may be used, for example, to mold moldings 8 used for vehicles, electrical appliances, various prototypes, and the like. FIG. 9 schematically shows an example of a molded body 8 molded by the dielectric heating molding apparatus 1. As shown in FIG.

(Mold 2)
As shown in FIG. 5, the mold 2 is made of various insulating materials other than metal. For the mold 2, various materials are used which have heating characteristics different from those of the molding material 80 when subjected to the application of an alternating electric field Y, etc., and which have the property of allowing the molded body 8 to be released from the mold. be done. The mold 2 is, for example, a rubber mold made of a rubber material, a resin mold made of a resin material, a ceramic mold made of a ceramic material, a cement mold made of a cement material, or a gypsum material. A gypsum mold or the like may be used.

Rubber materials include silicone rubber, fluorine rubber, etc. Resin materials include photo-curing resins, thermosetting resins, thermoplastic resins, etc. Ceramic materials include oxides, carbides, nitrides, and boron. There is a molded body 8 (sintered body) of an inorganic compound such as a compound.

The molding die 2 can be molded with a material having a smaller dielectric loss than the molding material 80, a material having a larger dielectric loss than the molding material 80, or the like. The value of dielectric loss depends on the type of material used as an insulator. Also, 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 a master model having the shape of the molding 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, processing can be applied to smoothen the stepped shape left on the molding surface 202 forming the cavity 20 due to lamination.

As shown in FIG. 5 , the mold 2 may be divided into two split mold parts 21 or may be divided into three or more split mold parts 21 . A parting surface 204 forming a parting line is formed between the split mold parts 21 . As shown in FIG. 5, the mold 2 may be a fixed mold in which the positions of the plurality of split mold parts 21 are fixed. As shown in FIG. A movable mold that can reduce the volume of the cavity 20 by relatively changing may be used.

The mold 2 may be a single mold entirely made of the same material, or a composite mold partially made of different materials. For example, as shown in FIG. 6, the composite mold includes a molding surface layer 211 formed along the molding surface 202 forming the cavity 20, and a general portion 210 as a portion of the mold 2 other than the molding surface layer 211. may be formed by In this case, the molding surface layer 211 is made of a material having a larger dielectric loss than the general portion 210 . Molding surface layer 211 contains at least one substance selected from the group consisting of carbon black, graphite, silicon carbide, ferrite, barium titanate, graphite and manganese dioxide, for example, in order to increase dielectric loss. 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 molded parts of various resins used as products. The shape of the cavity 20 may be various shapes, for example, the shape of a vehicle body, the shape of various cases, the shape of a functional component, a cylinder, a prism, or the like.

As shown in FIG. 5, the molding die 2 has a cavity 20 which is a space along the shape of the molding 8 to be molded, and a vacuum pump connected to an appropriate portion of the cavity 20 for vacuuming the inside of the cavity 20. A depressurization path 22 serving as a passage is formed. The reduced pressure path 22 connects the cavity 20 and the outer surface 201 of the mold 2 . A plurality of split mold parts 21 of the mold 2 are split so that the molded body 8 molded in the cavity 20 can be taken out.

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

These parts forming the pressure reduction path 22 include, for example, an end portion 203 that becomes a dead end in the cavity 20, as shown in FIG. In addition, the outer surface 201 of the mold 2 refers to the surface positioned outside the mold 2 . The gas in the cavity 20 includes, in addition to air, a substance remaining in the cavity 20 after being vaporized from a resin or the like.

If the molding die 2 is made of an elastically deformable rubber material, the molding die 2 may be deformed by the clamping force of the vacuum bag 3 . When the mold 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 molding 8 to be molded in the cavity 20 is adjusted.

As shown in FIG. 10 , the plurality of split mold parts 21 forming the mold 2 may be relatively movable so as to reduce the volume of the cavity 20 . Cavities 20 are formed between the plurality of split mold parts 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 receive the clamping force of the vacuum bag 3 and approach each other. On the other hand, when the split mold parts 21 are separated from each other after molding the molded body 8 , 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 molding material 80 may be resin such as thermoplastic resin or thermosetting resin, ceramic particles containing metal compounds, or the like. The ceramic particles may contain a resin binder such as a thermoplastic resin. The form of the molding material 80 may be amorphous particles, a solid material having a predetermined shape, a heat-melted liquid material, or the like. Also, the molding materials 80 in the form of particles, solids, liquids, etc. may be used in combination with each other.

If a granular or solid molding material 80 is used, the molding material 80 may be placed in the cavity 20 of the mold 2 before the mold 2 is placed in the vacuum bag 3. . Alternatively, the granular or liquid molding material 80 may be put into the cavity 20 of the mold 2 placed inside the vacuum bag 3 . Also, a portion of the granular or solid molding material 80 is placed in the cavity 20 of the mold 2 outside the vacuum bag 3, and the remainder of the granular molding material 80 or the liquid molding material 80 is It may be placed in the cavity 20 of the mold 2 placed in the vacuum bag 3 .

(Dielectric heating source 6)
As shown in FIGS. 3 and 4, the dielectric heating source 6 alternately heats the molding material 80 in the cavity 20 and the mold 2 by an alternating voltage applied between a pair of electrodes 61 arranged on both sides of the mold 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 with a pair of electrodes 61 . The frequency of the AC voltage generated by the dielectric heating source 6 is a high frequency electromagnetic wave including a wavelength range of 1 m to 100 m.

The dielectric heating molding apparatus 1 is used when the dielectric loss of the molding material 80 is greater than the dielectric loss of the mold 2 and vacuum 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 vacuum bag 3 in which the mold 2 is accommodated, and the high-frequency AC voltage is applied to the molding material 80, the mold 2, and the vacuum bag 3. When an alternating electric field Y is applied, the molding material 80 is heated by dielectric loss.

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

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

In addition, the plurality of split mold parts 21 can be relatively moved or deformed so as to reduce the volume of the cavity 20 by receiving a mold clamping force from the pair of electrodes 61 . The plurality of split mold parts 21 of this embodiment receive the mold clamping force from the vacuum bag 3 and the mold clamping force from the pair of electrodes 61 . Thereby, the mold clamping of the plurality of split mold parts 21 is performed more effectively.

When the pair of electrodes 61 is not used to press the plurality of split mold sections 21, the pair of electrodes 61 are arranged with a gap between them and the plurality of split mold sections 21 or the vacuum bag 3. may be

Further, in the dielectric thermoforming apparatus 1 , the pressure inside the cavity 20 may be directly reduced by the pressure reducing pump 4 without using the pressure reducing bag 3 . Alternatively, the plurality of split mold parts 21 may be clamped by a pair of electrodes 61 without using the vacuum bag 3 and the vacuum pump 4 .

The external shape of the electrode 61 in this embodiment is larger than the external shape of the mold 2 , and the entire mold 2 is arranged between the pair of electrodes 61 . The positional relationship between the pair of electrodes 61 and the mold 2 is fixed. On the other hand, if the outer shape of the electrode 61 is smaller than the outer shape of the mold 2 , a part of the mold 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 positioned at each portion within 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 interior of the decompression bag 3 and the cavity 20 of the mold 2 . The decompression pump 4 sucks out the gas (residual gas) in the decompression bag 3 to bring the interior of the decompression bag 3 and the interior of the cavity 20 of the mold 2 into a decompressed state (vacuum state) lower than the atmospheric pressure.

When the gas in the decompression bag 3 is sucked out, the decompression bag 3 is flexed and deflated, whereby pressure is applied from the decompression bag 3 to the molding die 2, and the plurality of split mold parts 21 of the molding die 2 move relatively. is prevented. Then, the mold 2 is clamped by the vacuum bag 3 . In addition, the cavity 20 of the mold 2 is also decompressed to prevent gas from remaining in the cavity 20 and to prevent the formation of voids, chips, etc. in the molded body 8 molded in the cavity 20.例文帳に追加

(Decompression pipe 5)
As shown in FIG. 1 , the dielectric thermoforming apparatus 1 of this embodiment includes a decompression pipe 5 for decompressing the inside of the decompression bag 3 by the decompression pump 4 . The decompression pipe 5 is connected to the decompression path 22 of the mold 2 arranged inside the decompression bag 3 and the decompression pump 4 arranged outside the decompression bag 3 . A portion of the decompression pipe 5 is arranged inside the decompression bag 3 , and the remainder 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 interior of the decompression bag 3 and the interior of the cavity 20 of the mold 2 . In other words, the decompression pipe 5 of this embodiment is configured to decompress both the cavity 20 of the mold 2 and the decompression bag 3 .

A tip portion 51 of the decompression pipe 5 is configured to be attached to a mounting portion 23 formed on the outer surface 201 of the mold 2 at a portion where the decompression path 22 is formed. The tip portion 51 of the decompression 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 decompression pipe 5 may be provided with a later-described valve 53 capable of opening and closing the flow path 50 . The decompression pipe 5 of this embodiment has a flexible pipe portion 54 on the side connected to the decompression pump 4 .

(Decompression bag 3)
As shown in FIGS. 7 and 8, the sheet material 30 forming the vacuum bag 3 is made of a flexible silicone film. A 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, the mold 2 can be made of transparent or translucent silicone rubber. By looking through the vacuum bag 3 and the mold 2 from the outside of the vacuum bag 3, the molding state of the molding material 80 in the cavity 20 can be confirmed.

The vacuum bag 3 may be made of a material having a smaller dielectric loss than the molding material 80 or the mold 2 . When the mold 2 having the molding surface layer 211 formed thereon is used, the decompression bag 3 is made of a material that allows near-infrared rays to pass more easily than the molding surface layer 211, or has a higher dielectric loss than the molding surface layer 211. It may be constructed from a small material.

The sheet material 30 forming the decompression bag 3 preferably has not only flexibility but also stretchability. Since the sheet material 30 also has elasticity, the vacuum bag 3 can be more easily brought into close contact with the mold 2 . Moreover, it is preferable that the sheet material 30 has non-adhesiveness or releasability and can be easily separated from the mold 2 or the like.

The sheet material 30 may be made of various flexible and stretchable rubber films other than the silicone film. Moreover, the sheet material 30 may be configured by at least a flexible resin film. A material having excellent heat resistance is preferably used for the sheet material 30 . The sheet material 30 may be composed of, for example, a fluororubber film, a fluororesin film, a polymethylpentene film, or the like.

The decompression bag 3 may be formed by adhering appropriate portions of a folded sheet material 30 with an adhesive. Alternatively, the decompression bag 3 may be formed by bonding two sheet materials 30 with an adhesive. When the decompression bag 3 is formed using a resin sheet material 30, the sheet material 30 may be melted and joined.

The vacuum bag 3 is formed in a size that accommodates at least the entire mold 2 . The vacuum bag 3 has an opening 31 for allowing the mold 2 to be taken in and out, and an opening chuck 32 for closing the opening 31 and sealing the interior of the vacuum bag 3 . Further, the decompression bag 3 is formed with an insertion port 33 into which the decompression pipe 5 is inserted, and the periphery 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 decompression bag 3 which is formed in a square shape. The opening chuck 32 sandwiches and seals a pair of ends of the sheet material 30 forming the opening 31 in the decompression bag 3 . The opening chuck 32 is formed by a combination of a female side chuck portion 321 having a groove and a male side chuck portion 322 having a convex portion that fits into the groove.

Further, when the molding die 2 becomes large, the decompression bag 3 is formed by placing a pair of sheet materials 30 on both sides of the molding die 2 and the decompression pipe 5 and then closing the peripheral edge of the pair of sheet materials 30. You may In other words, after the molding die 2 and the decompression pipe 5 are arranged between the pair of sheet materials 30, the periphery of the pair of sheet materials 30 is closed with a sealing zipper or the like, and the molding die 2 and the decompression pipe 5 are closed. may form a vacuum bag 3 with a portion of the

(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 interior of the decompression bag 3 in a reduced pressure state (vacuum state) lower than the atmospheric pressure. The decompression bag 3 has a function of clamping the molding die 2 and a function of maintaining the interior of the cavity 20 of the molding die 2 in a decompressed state.

As shown in FIGS. 1 , 3 and 7 , the decompression pipe 5 of this embodiment has a vent hole 52 for decompressing the inside of the decompression bag 3 . The vent hole 52 is formed in the side surface of the portion of the decompression pipe 5 that is placed inside the decompression bag 3 . In the decompression pipe 5 , the inside of the cavity 20 of the mold 2 can be evacuated through the tip opening 511 of the tip portion 51 , and the inside of the decompression bag 3 can be evacuated through the vent hole 52 . The tip opening 511 of the tip portion 51 of the decompression pipe 5 and the air hole 52 serve as a suction port for vacuuming by the decompression pump 4 .

When the decompression bag 3 is evacuated by the decompression pump 4 , the interior of the cavity 20 is evacuated through the tip opening 511 of the tip portion 51 of the decompression pipe 5 , and at the same time, the decompression bag 3 is evacuated through the vent hole 52 of the decompression pipe 5 . An internal vacuum is drawn. At this time, the gap in the decompression bag 3 where the distance between the decompression pump 4 and the vent 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 is in the cavity 20 . The flow rate of the gas sucked from the vent hole 52 is greater than the flow rate of the gas sucked from the tip opening 511 for the reason that the gap is larger than the gap of the tip end 511 . Then, the speed at which the inside of the vacuum bag 3 is decompressed is faster than the speed at which the inside of the cavity 20 is decompressed, and the degassing of the decompression bag 3 is stopped earlier than the degassing of the cavity 20 .

Further, as shown in FIGS. 3 and 4, as the gas in the vacuum bag 3 disappears, the sheet material 30 of the vacuum bag 3 comes into close contact with the vacuum pipe 5 and the mold 2 . The ventilation hole 52 is blocked by the sheet material 30 of the decompression bag 3 in the process of running out of the gas in the decompression bag 3 or when the gas in the decompression bag 3 is almost exhausted. When the vent hole 52 is blocked, the part to be evacuated by the decompression pump 4 is only the tip opening 511 of the tip portion 51 of the decompression pipe 5 , and the gas inside the cavity 20 is sucked through this tip opening 511 . In this way, the mold 2 is clamped by the vacuum bag 3 and the gas inside the cavity 20 is properly sucked.

By using the ventilation hole 52 formed on the side surface of the decompression pipe 5 as a suction port for vacuuming, the interior of the decompression bag 3 and the interior of the cavity 20 can be effectively decompressed with a very 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 reduction pipe 5 connected to the pressure reduction pump 4 is branched into two branch pipes, the first branch pipe is connected to the pressure reduction path 22 of the mold 2, and the second branch pipe A configuration in which the pipe is connected to the decompression bag 3 may be adopted.

As shown in FIGS. 1 and 7 , the vent hole 52 may be formed in one place on the side surface of the portion of the decompression pipe 5 that is arranged inside the decompression bag 3 , or may be formed in a plurality of places. The vent hole 52 is formed at a position that is not blocked by the mold 2 and is not immediately blocked by the vacuum bag 3 when the mold 2 is placed inside the vacuum bag 3 . The ventilation hole 52 is preferably formed in a portion of the decompression pipe 5 excluding a portion facing the sheet material 30 constituting the decompression bag 3 on the side surface of the decompression bag 3 . Specifically, the vent hole 52 is formed, for example, in a direction parallel to the sheet material 30 or in a direction inclined with respect to the sheet material 30 on the side surface of the portion of the decompression pipe 5 that is disposed inside the decompression 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 decompressed state in the decompression bag 3 when the decompression pipe 5 is disconnected from the decompression pump 4. It is preferable to provide Mold 2 , vacuum bag 3 , vacuum pipe 5 and valve 53 can be treated as one set separated from vacuum pump 4 . A ball valve, a needle valve, or the like, which is manually opened and closed by an operator, is used as the valve 53 .

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

By removing the vacuum bag 3 and the vacuum pipe 5 arranged in the mold 2 from the vacuum pump 4, the molding material 80 in the mold 2 is cooled and solidified after molding the molded body 8. In addition, the vacuum pump 4 can be used to mold another molding 8 using another vacuum bag 3 , mold 2 and vacuum pipe 5 . Then, the mold 2 placed inside the vacuum bag 3 can be moved to an arbitrary cooling place. Also, it is possible to easily secure a place and time for cooling the mold 2 and the molding material 80 .

(Dielectric heating molding method)
Next, the dielectric heat molding method using the dielectric heat molding apparatus 1 will be described in detail.
In the dielectric heat molding method, the molded body 8 is molded from the molding material 80 by performing a placement step, a decompression step, a heating step, and a cooling step.

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

When using particulate molding material 80 , the plurality of split mold sections 21 may be assembled together after the molding material 80 is placed in the recess forming the cavity 20 . Further, the particulate molding material 80 may be introduced into the cavity 20 formed by the mutually combined split mold sections 21 through the decompression path 22 or the inlet (not shown) formed in the split mold sections 21 . Also, part of the molding material 80 may be put into the cavity 20 of the mold 2 placed inside the vacuum bag 3 from outside the vacuum bag 3 .

As shown in FIGS. 2 and 7 , in the placement step, the decompression pipe 5 is connected to the decompression pump 4 , a part of the decompression pipe 5 is disposed inside the decompression bag 3 , and the decompression pipe 5 is placed in the decompression bag 3 . A state in which the insertion port 33 of the is sealed is formed. Then, the molding die 2 in which the molding material 80 is placed is inserted into the vacuum bag 3 from the opening 31 of the vacuum bag 3, and the attachment portion 23 of the molding die 2 is attached to the tip portion 51 of the vacuum pipe 5. be. Since the vacuum bag 3 is flexible, it can be arbitrarily deformed according to the size and shape of the mold 2 . After the mold 2 is placed in the vacuum bag 3 , the opening 31 of the vacuum bag 3 is closed by the opening chuck 32 . As a result, the inside of the vacuum bag 3 in which the mold 2 is arranged is sealed.

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

More specifically, for reasons such as a large pressure loss in the cavity 20, the gas in the cavity 20 is sucked after the pressure reduction by the pressure reduction pump 4 is started while the air vent 52 is not blocked. Hateful. In other words, the decompression pump 4 reduces the amount of gas in the decompression bag 3 through the vent hole 52 of the decompression pipe 5 compared to the suction force of the gas in the cavity 20 through the tip opening 511 of the tip portion 51 of the decompression pipe 5 . stronger attraction. However, when the gas inside the decompression bag 3 is sucked through the vent hole 52 of the decompression pipe 5 , the gas inside the cavity 20 is also sucked through the tip opening 511 of the tip portion 51 of the decompression pipe 5 .

When the inside of the vacuum bag 3 is decompressed and the vacuum bag 3 shrinks, the sheet material 30 of the vacuum bag 3 comes into close contact with the vacuum pipe 5 and the mold 2 . As shown in FIGS. 3 and 4, when the air hole 52 is entirely closed by the sheet material 30 in the process of deflating the decompression bag 3, only the tip opening 511 of the tip portion 51 of the decompression pipe 5 is opened. In this state, the inside of the cavity 20 is decompressed through the tip opening 511 of the tip portion 51 of the decompression pipe 5 .

(Heating process)
In the heating step, at least one of the molding material 80 inside the cavity 20 and the mold 2 is heated, and the molding material 80 inside the cavity 20 melts. In the heating process, a dielectric heating source 6 that applies a high-frequency AC voltage between a pair of electrodes 61 is used. A high-frequency alternating electric field Y is applied to the mold 2 from the pair of electrodes 61, and the mold 2 generates heat due to dielectric loss caused by this alternating electric field Y. 80 is heated.

When the molding surface layer 211 is formed on the mold 2, the alternating electric field Y causes the molding surface layer 211 to generate heat, and the heat transfer from the molding surface layer 211 heats the molding material 80 in the cavity 20. good too.

In the heating step, it is preferable to continue vacuuming by the decompression pump 4 so that the mold clamping force from the decompression bag 3 continues to act on the mold 2 . As shown in FIG. 10, when a molding die 2 capable of reducing the volume of the cavity 20 is used, when the molding material 80 inside the cavity 20 melts in the heating process, it receives the mold clamping force from the vacuum bag 3. , the plurality of split mold parts 21 constituting the mold 2 approach each other. Further, when an 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 clamping force of the decompression bag 3 and the volume of the cavity 20 is reduced. is sometimes reduced.

(Cooling process)
In the cooling step, the molten molding material 80 in the cavity 20 is cooled and solidified while the mold clamping force acts on the molding die 2 to obtain the molding 8 . In the cooling process, the heat remaining in the vacuum bag 3, the mold 2, and the molding material 80 may be radiated by natural convection of air, or may be radiated by forced convection of air by a fan or the like.

In the cooling step, the mold 2 may be left in a state in which the vacuum bag 3 and the vacuum pipe 5 arranged in the mold 2 are removed from the vacuum 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 flow path 50 of the decompression pipe 5 and the decompression bag 3 are maintained in a decompressed state. .

In the heating process and the cooling process, the pair of electrodes 61 may be used to press the plurality of split mold parts 21 of the mold 2 from outside. Then, the clamping force of the decompression bag 3 and the clamping force of the pair of electrodes 61 can be applied to the mold 2 .

When the molding material 80 in the cavity 20 of the mold 2 is cooled and solidified, the opening chuck 32 is removed from the opening 31 of the vacuum bag 3 and the mold 2 is removed from the opening 31 . Then, the plurality of split mold parts 21 of the mold 2 are separated from each other, and the compact 8 after molding is taken out from between the split mold parts 21 .

(Effect)
The dielectric heating molding apparatus 1 of this embodiment uses a dielectric heating source 6 having a pair of electrodes 61 to enable molding of a molded body 8 having a large size, a complicated shape, or the like.

When molding the molded body 8 , the molding die 2 having the molding material 80 arranged in the cavity 20 is arranged between the pair of electrodes 61 of the dielectric heating source 6 . Further, the mold 2 is placed inside the vacuum bag 3 , and the inside of the vacuum bag 3 and the inside of the cavity 20 are evacuated by the vacuum pump 4 . 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 mold 2 inside the cavity 20 . Then, the molding material 80 in the cavity 20 generates heat due to dielectric loss, or the molding material 80 in the cavity 20 is heated by heat transfer from the mold 2 that generates heat due to dielectric loss, and the molding material 80 melt. After that, the molding material 80 is cooled and solidified to obtain the molding 8 .

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

Moreover, when a high-frequency AC voltage is used, the molding material 80 in the cavity 20 is also likely to generate heat due to the alternating electric field Y as compared to 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 placed between the pair of electrodes 61 is , the alternating electric field Y applied to this portion can melt more appropriately, and the compact 8 can be molded appropriately.

Therefore, according to the dielectric heating molding apparatus 1 and the dielectric heating molding method of the present embodiment, the degree of freedom of the size, shape, etc. of the molding 8 to be molded can be increased.

<Embodiment 2>
This embodiment shows a dielectric heating molding apparatus 1 in which the dielectric heating source 6 and another heating source are used together.
As shown in FIG. 11, the other heating source may be a heater 62 which is provided on at least one of the pair of electrodes 61 of the dielectric heating source 6 and which generates heat when energized. The heater 62 can be provided in each electrode 61 and embedded in a plurality of placement 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 simultaneously with 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 partial unevenness in the heating temperature of the molding material 80 and heat the entire molding material 80 as uniformly as possible.

Further, as shown in FIG. 12, the other heating source may be a hot air heating source 7 that heats the mold 2 with hot air H through the vacuum bag 3 . The hot air heating source 7 is composed of a heater 71 that heats gas and a fan 72 that blows the gas heated by the heater 71 as hot air H to the mold 2 . When the hot air heating source 7 is used, the molding material 80 in the cavity 20 is heated by the hot air heating source 7 simultaneously with 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. In this case as well, it is possible to suppress partial unevenness in the heating temperature of the molding material 80 and heat the molding material 80 as a whole as uniformly as possible.

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

Other configurations, functions and effects of the dielectric heating molding apparatus 1 and the dielectric heating molding method of this embodiment are the same as those of the first embodiment. Also, in this embodiment, the constituent elements indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment.

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

In this case, the dielectric heating source 6 also has a function of cooling the mold 2 through the vacuum bag 3 by the electrode 61 cooled by the cooling water C flowing through the cooling channel 63 . In this case, the mold 2 can be forcibly cooled by the electrodes 61 cooled by the cooling water C flowing through the cooling channels 63 in the cooling step of the dielectric heating molding method. Therefore, the molding material 80 melted in the cavity 20 of the molding die 2 can be quickly solidified with a simple configuration in which the cooling channel 63 is formed in the electrode 61 .

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

Also, the pressure reduction path 22 communicating with the cavity 20 may be formed at a plurality of locations on the outer surface 201 of the mold 2 . In this case, when the inside of the vacuum bag 3 is evacuated, the inside of the cavity 20 can be evacuated from the multiple vacuum paths 22 . In particular, the plurality of pressure reduction paths 22 may be formed at positions communicating with the dead end 203 in the cavity 20, as shown in FIG.

Other configurations, functions and effects of the dielectric heating molding apparatus 1 and the dielectric heating molding method of this embodiment are the same as those of the first embodiment. Also, in this embodiment, the constituent elements indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment.

The present invention is not limited to only each embodiment, and further different embodiments can be configured without departing from the scope of the invention. In addition, the present invention includes various modifications, modifications within the equivalent range, and the like. Further, the technical idea of the present invention also includes combinations, forms, and the like of various constituent elements assumed from the present invention.

REFERENCE SIGNS LIST 1 Dielectric heating molding device 2 Mold 20 Cavity 201 Outer surface 202 Molding surface 21 Split mold part 210 General part 211 Molding surface layer 22 Decompression path 23 Mounting part 25 Mold clamping 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 pipe 51 Tip part 511 Tip opening 52 Vent 53 Valve 6 Dielectric heating source 61 Electrode 62 Heater 63 Cooling channel 7 Warm air heating source 71 Heater 72 Fan 8 compact 80 molding material Y alternating electric field

Claims (11)

an insulating mold having a cavity in which a molded body is molded from a molding material and having a property of generating heat due to dielectric loss;
A dielectric heating source that heats the molding material in the cavity by applying an alternating electric field to the molding material in the cavity and the molding die by an alternating voltage applied between a pair of electrodes arranged on both sides of the molding die. and
The mold is divided into a plurality of divided mold parts,
The dielectric heating molding apparatus , wherein the plurality of split mold parts are capable of relative movement or deformation so as to reduce the volume of the cavity under the clamping force of the pair of electrodes . an insulating mold having a cavity in which a molded body is molded from a molding material and having a property of generating heat due to dielectric loss;
A dielectric heating source that heats the molding material in the cavity by applying an alternating electric field to the molding material in the cavity and the molding die by an alternating voltage applied between a pair of electrodes arranged on both sides of the molding die. and
A cooling channel through which cooling water flows is formed in at least one of the pair of electrodes,
The dielectric heating molding apparatus , wherein the dielectric heating source also has a function of cooling the molding die by the electrode cooled by the cooling water flowing through the cooling channel . At least one of the pair of electrodes is provided with a heater that generates heat when energized,
3. The dielectric heating molding apparatus according to claim 1, wherein the molding material in the cavity is heated by the heater simultaneously with or alternately with heating by the dielectric heating source, or before and after heating by the dielectric heating source. . The dielectric heating molding device further comprises a hot air heating source for heating the mold with hot air,
3. The dielectric according to claim 1, wherein the hot air heating source heats the molding material in the cavity simultaneously or alternately with heating by the dielectric heating source, or before and after heating by the dielectric heating source. Thermoforming equipment. The mold is formed with a pressure reduction path connecting the cavity and the outer surface,
The dielectric thermoforming device includes:
a decompression bag formed in a bag shape from a flexible sheet material and containing the molding die therein;
The dielectric thermoforming apparatus according to any one of claims 1 to 4 , further comprising a decompression pump that decompresses the interior of the decompression bag and decompresses the interior of the cavity via the decompression path. a placement step in which the molding material is placed in a cavity of an insulating mold having a 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 mold by an alternating voltage applied between a pair of electrodes of the dielectric heating source located on opposite sides of the mold. a heating step in which the molding material in the cavity is heated;
a cooling step of cooling the mold and the molding material to obtain a molded body from the molding material. The mold is divided into a plurality of divided mold parts,
7. The dielectric heating molding according to claim 6 , wherein in the heating step, the plurality of split mold parts receive mold clamping force from the pair of electrodes and relatively move or deform so as to reduce the volume of the cavity. Method. At least one of the pair of electrodes is provided with a heater that generates heat when energized,
8. The method according to claim 6 , wherein in the heating step, the molding material in the cavity is heated by the heater simultaneously with or alternately with heating by the dielectric heating source, or before and after heating by the dielectric heating source. Dielectric thermoforming method as described. In the heating step, a hot air heating source that heats the mold with hot air is further used, and the hot air is heated simultaneously with or alternately with the heating by the dielectric heating source, or before and after the heating by the dielectric heating source. 8. The dielectric heating molding method according to claim 6 , wherein the molding material in the cavity is heated by a heat source. A cooling channel through which cooling water flows is formed in at least one of the pair of electrodes,
10. The dielectric heating molding method according to any one of claims 6 to 9 , wherein in said cooling step, said molding die is cooled by said electrode cooled by cooling water flowing through said cooling channel. The mold is formed with a pressure reduction path connecting the cavity and the outer surface,
In the arranging step, a vacuum bag that is formed in a bag shape from a flexible sheet material and that accommodates the molding die is used. The arranged mold is arranged,
After the arranging step, the interior of the decompression bag and the interior of the cavity via the decompression path are decompressed by a decompression pump, and the decompression bag is in close contact with the mold, and the clamping force of the decompression bag is applied to the mold. A depressurization step is performed which acts on
The dielectric heating molding method according to any one of claims 6 to 10 , wherein in said cooling step, said clamping force is maintained in a state of acting on said molding die.

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