Thermoforming device and thermoforming method

A thermoforming device includes: an upper hot plate including a first heating surface configured to heat a sheet from above; a lower hot plate including a second heating surface configured to heat the sheet from below; and a substrate-supplying unit including a base configured to hold a molded substrate, and configured to attach the molded substrate to and detach the molded substrate from the base and to dispose the molded substrate at a molding position below the first heating surface with the sheet interposed therebetween, in which the upper hot plate and the lower hot plate are configured to heat the sheet simultaneously from an upper surface and a lower surface of the sheet, the lower hot plate is provided to be movable in a horizontal direction with respect to a position below the upper hot plate, and the thermoforming device die-molds or adheres, onto the molded substrate held by the base, the sheet softened by being heated by the upper hot plate and the lower hot plate.

TECHNICAL FIELD

The present invention relates to a thermoforming device and a thermoforming method.

Priority is claimed on Japanese Patent Application No. 2015-215036, filed Oct. 30, 2015, the content of which is incorporated herein by reference.

BACKGROUND ART

In general, as an apparatus for attaching a cover sheet (hereinafter, referred to as a sheet) to an outer surface of a molded substrate, a vacuum press lamination-forming apparatus using radiation heating in upper and lower chambers, a thermoforming device using hot plate heating, or the like, is known.

For example, Patent Document 1 discloses a vacuum press lamination-forming apparatus. The vacuum press lamination-forming apparatus includes upper and lower chambers. The lower chamber can set a sheet to a circumferential edge portion close to the upper chamber while accommodating a molded substrate. The upper chamber has a hot plate including a heater thereabove. The upper chamber is connected to a vacuum tank and a pressure tank and can evacuate and pressurize the inside of the chamber constituted by the upper and lower chambers.

The lower chamber is connected to the vacuum tank and can evacuate the inside of the chamber.

In the vacuum press lamination-forming apparatus disclosed in Patent Document 1, the lower chamber is depressurized in a state in which an intermediate chamber is depressurized and a synthetic resin sheet is pulled away from the substrate. Accordingly, air between the substrate and the synthetic resin sheet is sufficiently discharged without being hindered by the synthetic resin sheet. After that, the upper chamber is pressurized. For this reason, the synthetic resin sheet is adhered to the substrate in a vacuum state due to a pressure difference between the upper chamber and the lower chamber.

DOCUMENT OF RELATED ART

PATENT DOCUMENT

SUMMARY OF INVENTION

Technical Problem

However, the thermoforming method in the related art has the following problems. That is, the sheet is suctioned to a heating surface of the hot plate from one direction which is from an upper side and heated. For this reason, an adhering surface (a lower surface) of the sheet needs to be heated from an upper surface of the sheet until the adhering surface is softened to a state required for coating. For this reason, a temperature of the heating surface is increased and a heating time when a sheet upper surface is absorbed to the heating surface of the hot plate is increased. For this reason, a surface roughness of the heating surface may be transferred to the sheet upper surface. Thus, since the sheet to which the surface roughness is transferred when the front surface of the molded substrate is coated with the sheet appears on the front surface of the thermoformed article, there is room for improvement in design properties. In addition, in mass production of thermoformed articles, it is required to shorten the heating time of the sheet. In particular, when the sheet is thick, a heating time for softening the sheet is necessary. For this reason, it has been required to reduce the molding time.

In consideration of the above-mentioned problems, the present invention provides a thermoforming device and a thermoforming method allowing a reduction in heating time of a sheet to be achieved and design properties of a thermoformed article to be improved.

Solution to Problem

A thermoforming device according to a first aspect of the present invention includes an upper hot plate including a first heating surface configured to heat a sheet from above; a lower hot plate including a second heating surface configured to heat the sheet from below; and a substrate-supplying unit including a base configured to hold a molded substrate, and configured to attach the molded substrate to and detach the molded substrate from the base and to dispose the molded substrate at a molding position below the first heating surface with the sheet interposed therebetween, wherein the upper hot plate and the lower hot plate are configured to heat the sheet simultaneously from an upper surface and a lower surface of the sheet, the lower hot plate is provided to be movable in a horizontal direction with respect to a position below the upper hot plate, and the thermoforming device die-molds or adheres, onto the molded substrate held by the base, the sheet softened by being heated by the upper hot plate and the lower hot plate.

A thermoforming method according to a second aspect of the present invention is a thermoforming method using a thermoforming device including: an upper hot plate including a first heating surface configured to heat a sheet from above; a lower hot plate including a second heating surface configured to heat the sheet from below; and a substrate-supplying unit including a base configured to hold a molded substrate, and configured to attach the molded substrate to and detach the molded substrate from the base, and to dispose the molded substrate at a molding position below the first heating surface with the sheet interposed therebetween, the thermoforming method including: installing the molded substrate on the base and disposing the base at the molding position; disposing the lower hot plate at a position below the upper hot plate with a gap therebetween; disposing the sheet between the upper hot plate and the lower hot plate; heating upper and lower surfaces of the sheet using the upper hot plate and the lower hot plate, respectively; retracting the lower hot plate from the position below the upper hot plate and forming a closed space below the sheet and surrounded by the sheet and the substrate-supplying unit; and depressurizing an inside of the closed space, and die-molding the sheet softened by the heating, or adhering the sheet to the molded substrate.

In the above-mentioned aspects, the upper surface side of the sheet is heated by the first heating surface of the upper hot plate, and the lower surface side is heated by the second heating surface of the lower hot plate. Accordingly, both of the upper and lower surfaces of the sheet are simultaneously heated. For this reason, a reduction in heating time can be achieved. Then, after the sheet is softened by the heating, as the lower hot plate is moved in a lateral direction from the position below the upper hot plate, the sheet can be uniformly die-molded, or coated on the entire front surface of the molded substrate of the substrate-supplying unit.

In this way, since both of the upper and lower surfaces of the sheet are simultaneously heated by the upper hot plate and the lower hot plate, a temperature of the upper hot plate can be lowered to heat the sheet. For this reason, it is possible to prevent transfer of a surface roughness of the first heating surface to the upper surface of the sheet due to heating of the upper hot plate, and reduce deterioration in design properties of the front surface of the thermoformed product after thermoforming.

In addition, in the above-mentioned aspect, the lower surface side of the sheet to which an adhesive agent is adhered can also be heated by the lower hot plate. For this reason, the adhesive agent can be sufficiently softened, and an adhesive strength of the sheet adhered to the molded substrate can be improved.

Further, in the above-mentioned aspect, since both of the upper and lower surfaces of the sheet can be heated, the embodiment can also be applied to a sheet having a large thickness. That is, even in a sheet having a thickness such that the lower surface of the sheet cannot be heated to a required temperature when heated by only the upper hot plate, the entire sheet can be heated to a sheet-softening temperature required for die-molding, or coating, by heating the lower surface of the sheet using the lower hot plate.

In addition, in the above-mentioned aspect, since the upper hot plate and the lower hot plate are individually provided, the temperature can be adjusted by applying different temperatures between the upper hot plate and the lower hot plate. For this reason, for example, the temperature of the lower surface of the sheet can be increased to higher than that of the upper surface of the sheet, the upper surface of the sheet can prevent transfer due to a high temperature of the upper hot plate, and the lower surface of the sheet can sufficiently soften an adhesive agent using a high heating temperature of the lower hot plate. Accordingly, according to conditions of the sheet such as a material, a thickness dimension, or the like, of the sheet, appropriate heating with respect to the sheet can be performed, and a quality of the thermoformed article can be improved.

In the above-mentioned first aspect, the upper hot plate may suction the sheet to the first heating surface and may contact and heat the upper surface of the sheet, and the lower hot plate may be disposed below the sheet with a gap therebetween, and may be configured to heat the lower surface of the sheet using radiant heat from the second heating surface.

In the above-mentioned aspect, the upper hot plate can be heated by suctioning and bringing the sheet into contact with the first heating surface. Meanwhile, the lower hot plate is configured to heat the lower surface of the sheet using radiant heat from the second heating surface. For this reason, both of the upper and lower surfaces of the sheet can be heated by a simple structure including only, for example, a heater configured to heat the second heating surface only.

In the above-mentioned first aspect, the substrate-supplying unit may be provided to be movable between the molding position disposed below the upper hot plate and a retreat position provided with a gap from the molding position.

In the above-mentioned aspects, during heating of the sheet, the substrate-supplying unit can be retracted from the molding position to dispose the lower hot plate at the molding position. Then, after termination of the heating of the lower hot plate, the lower hot plate is retracted from the molding position. Then, the substrate-supplying unit can be disposed at the molding position to die-mold the sheet into shape with respect to the molded substrate, or cover the molded substrate with the sheet. For this reason, since the lower hot plate and the substrate-supplying unit can be exchanged with each other at the molding position, the entire height of the thermoforming device can be suppressed.

Effects of Invention

According to the thermoforming device and the thermoforming method of the aspect of the present invention, a reduction in heating time of a sheet can be achieved, and improvement of design properties of a thermoformed product can be achieved.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a thermoforming device and a thermoforming method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown inFIGS. 1 to 3, a thermoforming device1according to the embodiment employs a hot plate heating method. The thermoforming device1is a device configured to cover a front surface6aof a molded substrate6with a sheet4softened by heating hot plates3(an upper hot plate3A and a lower hot plate3B). The hot plates3(the upper hot plate3A and the lower hot plate3B) are installed as a pair of upper and lower hot plates. As shown inFIG. 7, the molded substrate6is disposed in a chamber2A of a lower frame2(a substrate-supplying unit).

Here, as a thermoformed article6A (seeFIG. 9), for example, parts having front and back surfaces such as automobile parts or the like are employed. The thermoformed product6A is a molded product that is thermoformed by suctioning the sheet4, which is softened by heating, onto the front surface6aof the molded substrate6formed of a resin and covering the front surface6awith the sheet4. In the embodiment, the molded substrate6has a capped cylindrical shape.

The thermoforming device1includes the lower frame2, the upper hot plate3A and the lower hot plate3B. The lower frame2has a space (the chamber2A) in which the molded substrate6shown inFIG. 7can be accommodated. The upper hot plate3A has a first heating surface3a1configured to heat the sheet4from above. The lower hot plate3B has a second heating surface3b1configured to heat the sheet4from below. In addition, a sheet transport apparatus5configured to supply the sheet4to heating surfaces3a1and3b1of the hot plates3A and3B is provided in the thermoforming device1according to the embodiment.

The lower frame2, the upper hot plate3A and the lower hot plate3B are individually provided. The upper hot plate3A is disposed above the lower frame2disposed at a predetermined molding position P0and provided to be vertically movable with respect to the lower frame2. The lower frame2is provided to be movable between the molding position P0and a first retreat position P1in a lateral direction (a horizontal direction) (an arrow D3direction). In addition, the lower hot plate3B is provided to be movable between the molding position P0disposed below the upper hot plate3A with a gap therebetween and a second retreat position P2in a lateral direction (a horizontal direction) (an arrow D4direction). The second retreat position P2is a position different from the above-mentioned first retreat position P1. The lower frame2and the lower hot plate3B are disposed not to interfere with each other. That is, when either one of these is disposed at the molding position P0, the other is disposed at the retreat position P1or P2. Further, in the embodiment, a moving direction (the lateral direction D3) of the lower frame2and a moving direction (the lateral direction D4) of the lower hot plate3B are perpendicular to each other.

Here, each operations of the lower frame2, the upper hot plate3A, the lower hot plate3B and the sheet transport apparatus5are controlled by a control unit (not shown).

Further, while not shown in particular, a cutting tool configured to trim off unnecessary portions of the sheet4covering the molded substrate6is provided in the thermoforming device1according to the embodiment.

The lower frame2is formed from a metal member formed of stainless steel or the like in a rectangular shape when seen in plan view. The lower frame2includes a sidewall21having four surfaces, a bottom panel22(a base) corresponding to a bottom portion, and a frame stand23on which the sidewall21and the bottom panel22are placed. A substrate tool24configured to hold the molded substrate6is fixed onto the bottom panel22in the chamber2A on an inner side surrounded by the bottom panel22and the sidewall21.

The sidewall21is provided such that a frame upper edge portion21ais higher than the accommodated substrate tool24and the molded substrate6held by the substrate tool24. The frame upper edge portion21ais a portion that sandwiches the sheet4between the upper hot plate3A and the frame upper edge portion21a. That is, the upper hot plate3A air-tightly contacts the frame upper edge portion21awith the sheet4interposed therebetween, and thus, the lower frame2and the upper hot plate3A are in a closed state and the inside of the chamber2A becomes a closed space. For this reason, in a state in which the sheet4is sandwiched between the frame upper edge portion21aand the upper hot plate3A, the space is air-tightly divided into upper and lower spaces with the sheet4interposed therebetween.

The bottom panel22is formed in a shape smaller than that of the upper hot plate3A when seen in plan view, and provided on the frame stand23.

The frame stand23is provided to be movable on a floor between the molding position P0and the first retreat position P1. The first retreat position P1is a position deviated from the molding position P0when seen in plan view, and the first retreat position P1becomes a substrate supply position at which the molded substrate6is supplied onto the substrate tool24. Further, the first retreat position P1may be a position at which the molded substrate6(or, the thermoformed article6A) is detachable from the substrate tool24. In addition, the molding position P0and the first retreat position P1may partially overlap each other when seen in plan view. Further, the frame stand23can be omitted, and as long as the bottom panel22is movable as described above, an installation place and a shape of the bottom panel22are also not limited in particular.

In addition, a plurality of vent holes2bcommunicating with the chamber2A are formed in an outer circumferential edge of the bottom panel22. The vent holes2bare connected to a vacuum pump (not shown). Upon molding, as the vacuum pump is operated to evacuate the chamber2A, the chamber2A is depressurized.

The substrate tool24is formed of a metal or the like disposed on the bottom panel22. A holding section24aconfigured to hold the molded substrate6that is adhered thereto and formed of a resin or the like is formed on an upper section of the substrate tool24.

The holding section24ais formed in a shape slightly smaller than that of the molded substrate6when seen in plan view.

For this reason, an outer circumferential portion of the molded substrate6extends outward from a side circumferential surface of the holding section24a, and the molded substrate6is holdable with respect to the substrate tool24in a state in which the molded substrate6covers an upper section of the holding section24a.

Then, as compressed air is introduced into the chamber2A from the upper hot plate3A by a pressure tank or the like (not shown), the sheet4is lowered toward the bottom panel22. Then, the molded substrate6held by the substrate tool24is covered and adhered by the sheet4.

The upper hot plate3A is a flat-plate-shaped component configured to soften the sheet4by suctioning the sheet4to the lower surface and heating the sheet4. The upper hot plate3A has the first heating surface3a1constituted of a planar surface on the lower surface.

The upper hot plate3A is provided to ascend and descend in a vertical direction approaching or moving away from the molding position P0disposed thereunder. Then, in a state in which the upper hot plate3A is moved downward, the upper hot plate3A is disposed while being closely adhered to the frame upper edge portion21aof the lower frame2disposed on the molding position P0from above.

Further, an expansion device (not shown) having a rod that expands and contracts in the vertical direction is provided above the upper hot plate3A. The upper hot plate3A is movable in the vertical direction by the expansion device.

A plurality of heaters31are provided on an upper surface3cof the upper hot plate3A at predetermined intervals. A plurality of vent holes32opening in the first heating surface3a1are formed in the first heating surface3a1of the upper hot plate3A at predetermined intervals. Each of the vent holes32is connected to be switchable between a vacuum pump (not shown) and a booster pump (not shown). The vacuum pump includes a vacuum tank configured to vacuum suction the first heating surface3a1side. The booster pump includes a pressure tank configured to store air compressed by a compressor.

According to the above-mentioned configuration, upon thermoforming, connection to the vacuum tank and the pressure tank can be appropriately switched, and the vacuum tank maintained in a vacuum state can be opened to vacuum suction the sheet4through the vent holes32to closely attach the sheet4to the first heating surface3a1. In addition, the compressed air supplied from the pressure tank through the vent holes32can be supplied into the chamber2A from the first heating surface3a1and pressurized, and the sheet4can be lowered toward the molded substrate6. A degree of vacuum can be increased through direct suction by driving of the vacuum pump without providing a vacuum tank.

The lower hot plate3B is a flat-plate-shaped component configured to heat the sheet4at an upper surface side from below using radiant heat. The lower hot plate3B has the second heating surface3b1formed on an upper surface as a flat surface. The lower hot plate3B is provided to be movable forward and backward in a lateral direction with respect to a position below the upper hot plate3A (the molding position P0in the embodiment). That is, as described above, the lower hot plate3B is provided to be freely movable along, for example, a slide rail or the like (not shown) between the molding position P0and the second retreat position P2. In a state in which the lower hot plate3B is disposed at the molding position P0, the second heating surface3b1is set to be disposed at a height at a predetermined gap in the vertical direction from the first heating surface3a1of the upper hot plate3A disposed at a heating position. A plurality of heaters33are provided on a lower surface3d of the lower hot plate3B at predetermined intervals.

The second retreat position P2is not particularly limited as long as the position does not interfere with other members such as the sidewall21or the like of the lower frame2disposed at the molding position P0.

The sheet4is a known multi-layered sheet having a printing layer and a protective film or a carrier film (not shown) formed on a front surface of the printing layer, and an adhesive layer formed on a back surface of the printing layer. The sheet4is formed of a material which can be heated and formed by the heating plates3A and3B and solidified upon cooling. In the embodiment, a roll sheet wound in a roll shape is employed as the sheet4.

The molded substrate6is an object to which the sheet4is covered and adhered, for example, a main body of a molded product formed of a thermoplastic resin such as a polypropylene-based resin, a polyethylene-based resin, or the like. However, a material of the molded substrate6is not limited to the resin.

As shown inFIG. 1, the sheet transport apparatus5is provided to supply the sheet4to a position between the heating surfaces3a1and3b1of the hot plates3A and3B. The sheet transport apparatus5includes a sheet support section52, a sheet-unwinding section58, a sheet-cutting section54and a cut sheet-holding section56, which are components for accomplishing the above-mentioned purposes.

The sheet support section52supports the sheet4such that it can be unwound. The sheet support section52is configured to sandwich and support the sheet4at a position at which unwinding of the sheet4is started, from a roll section51that supports a core4x of the sheet4. The sheet support section52may be configured to pass the sheet4therethrough in an unwinding direction D1of the sheet4along an extending direction of the heating surfaces3a1and3b1of the hot plates3A and3B or simply may be configured to place the sheet4thereon.

The sheet-unwinding section58is configured to detachably hold the sheet end4eof the sheet4, and unwind a sheet end4eof the sheet below the first heating surface3a1of the upper hot plate3A in the unwinding direction D1. For example, the sheet-unwinding section58is provided to be able to reciprocate in the unwinding direction D1and a returning direction D2opposite to the unwinding direction D1. That is, the sheet-unwinding section58can freely reciprocate between the position shown by a solid line inFIG. 1and a position shown by a double dotted-dashed line inFIG. 1.

The sheet-cutting section54is disposed in front of the sheet support section52in the unwinding direction D1. The sheet-cutting section54has a configuration in which the sheet4held by the sheet-unwinding section58is cut on a rear side in the unwinding direction D1of the heating surfaces3a1and3b1of the hot plates3A and3B. For example, the sheet-cutting section54may be a cutter extending in a widthwise direction of the sheet4, or may be a cutter that can scan the sheet4parallel to the widthwise direction of the sheet4. In addition, the cutter may be configured to be able to ascend and descend in a direction approaching or moving away from the sheet4.

The cut sheet-holding section56is disposed in front of the sheet-cutting section54in the unwinding direction D1. The cut sheet-holding section56has a configuration of holding the sheet end4eof the sheet4cut by the sheet-cutting section54. The cut sheet-holding section56is constituted by, for example, a member able to ascend and descend in a direction approaching or moving away from the sheet4.

The sheet transport apparatus5configured as above can continuously supply the sheet4in the extending direction of the heating surfaces3a1and3b1every time the thermoformed product6A is formed while sequentially unwinding the sheet4in the unwinding direction D1of the sheet4by the sheet-unwinding section58and cutting the sheet4by the sheet-cutting section54.

Then, as shown inFIGS. 4 to 9, the thermoforming device1is configured to dispose the sheet4along the first heating surface3a1of the upper hot plate3A by the sheet transport apparatus5, to move the lower hot plate3B to the molding position P0, to heat the sheet4by the upper hot plate3A and the lower hot plate3B, to retract the lower hot plate3B to the second retreat position P2, to move the lower frame2disposed at the first retreat position P1and holding the molded substrate6on the substrate tool24to the molding position P0, to sandwich the sheet4softened through heating by lowering of the upper hot plate3A between the frame upper edge portion21aand the upper hot plate3A, and to control a control unit (not shown) such that air is compressed through the vent holes32of the first heating surface3a1of the upper hot plate3A.

Further, a cutting tool (not shown) is provided on, for example, the lower frame2and has a blade section disposed to be directed upward. The cutting tool is disposed at a position facing the molded substrate6held on the substrate tool24at a predetermined gap therefrom in the vertical direction. Since the cutting tool is configured in this way, the blade section of the cutting tool can perform trimming by cutting the sheet4covered on the molded substrate6.

Next, a thermoforming method when the thermoformed product6A is molded using the above-mentioned thermoforming device1, and actions of the thermoforming device and the thermoforming method will be described with reference to the accompanying drawings.

Further, a state in which the lower frame2, the upper hot plate3A and the lower hot plate3B are disposed at positions shown inFIG. 1is referred to as an initial state. That is, the initial state is a state in which the upper hot plate3A is disposed above the molding position P0, the lower frame2is disposed at the first retreat position P1, and the lower hot plate3B is disposed at the second retreat position P2.

As shown inFIG. 4, first, the molded substrate6is installed on the substrate tool24disposed on the bottom panel22of the lower frame2positioned at the first retreat position P1. Accordingly, the molded substrate6is held on the substrate tool24in a state where the molded substrate6is adhered on the substrate tool24. Further, a first process of mounting the molded substrate6on the substrate tool24may be at any timing as long as the lower frame2is in a state of being disposed at the first retreat position P1as shown inFIG. 2(a second process to a fourth process, which will be described below).

Then, a second process of supplying the sheet4to extend along the first heating surface3a1of the upper hot plate3A by the sheet transport apparatus5is performed. Specifically, the sheet end4eof the sheet4is held by the sheet-unwinding section58previously moved to the rear side in the unwinding direction D1. After that, the sheet-unwinding section58that holds the sheet end4eis moved toward a front side in the unwinding direction D1of the first heating surface3a1of the upper hot plate3A along the unwinding direction D1. Then, when movement of the sheet-unwinding section58is terminated, the sheet4is disposed below the first heating surface3a1of the upper hot plate3A.

Then, the unwound sheet4is cut by the sheet-cutting section54and separated from the roll section51.

Next, as shown inFIGS. 5 and 6, in a third process, the lower hot plate3B disposed at the second retreat position P2is moved in a lateral direction to be disposed at the molding position P0. The second heating surface3b1of the lower hot plate3B disposed at the molding position P0faces the first heating surface3a1of the upper hot plate3A in the vertical direction while the sheet4is interposed therebetween as shown inFIG. 6. Here, the second heating surface3b1is disposed at a predetermined gap from a lower surface4bof the sheet4.

Further, in the above-mentioned second process and third process, the third process may be performed prior to the second process, or both of the processes may be performed substantially simultaneously.

After that, a fourth process of heating the sheet4is performed by the upper hot plate3A and the lower hot plate3B. As shown inFIGS. 5 and 6, the upper hot plate3A is heated by the heaters31, and the above-mentioned vacuum pump in the upper hot plate3A is operated to evacuate and suction a space between the first heating surface3a1and the sheet4and decompress the space through the vent holes32. Accordingly, the sheet4is suctioned to the first heating surface3a1and heated. Here, the sheet4is heated by a contact with the first heating surface3a1from an upper surface4athereof.

Meanwhile, the lower hot plate3B is heated by a heater (not shown), and the lower surface4bof the sheet4is heated by radiant heat of the lower hot plate3B.

Next, as shown inFIG. 7, after termination of the heating process (the fourth process) of the sheet4, a fifth process of moving the lower frame2to the molding position P0is performed.

In the fifth process, first, the lower hot plate3B is laterally moved from the molding position P0to the second retreat position P2in the arrow D1direction. After that, the lower frame2in a state in which the molded substrate6is held is moved to the molding position P0provided with a gap from the first retreat position P1in the arrow D3direction shown inFIG. 2, i.e., a position below the upper hot plate3A. Here, the sheet4is in a state of being suctioned to the first heating surface3a1of the upper hot plate3A. Then, the upper hot plate3A and the lower frame2are disposed to overlap each other when seen in plan view.

Next, as shown inFIG. 6, in a sixth process, the previously unwound sheet4is cut to a size sufficient for covering and adhesion to the molded substrate6.

Specifically, in the unwinding direction of the sheet4, the sheet4is cut by the sheet-cutting section54on a rear side of the first heating surface3a1of the upper hot plate3A in the unwinding direction D1, i.e., between the sheet support section52and the cut sheet-holding section56. The sheet4is also held by the cut sheet-holding section56before and after cutting the sheet4. In this way, as the sheet4is held by both of the support member of the sheet support section52and the cut sheet-holding section56, after cutting the sheet4, a sheet end4fis held by the cut sheet-holding section56and a sheet end4gis supported by the sheet support section52.

Next, in a seventh process, as shown inFIG. 7, the lower frame2that accommodates the molded substrate6approaches relatively close to the upper hot plate3A. Then, the lower frame2contacts the upper hot plate3A with the sheet4therebetween, and the inside of the chamber2A is brought into a closed state. In the thermoforming method according to the embodiment, the upper hot plate3A is moved downward, and the outer circumferential portion of the first heating surface3a1is brought into close contact with the frame upper edge portion21aof the lower frame2with the sheet4interposed therebetween. Here, the sheet4is sandwiched between the frame upper edge portion21aand the upper hot plate3A throughout the entire circumference with no gap. In addition, the chamber2A is formed into a closed space when an upper opening of the lower frame2is closed.

Next, as shown inFIG. 8, in an eighth process, the closed space in the chamber2A surrounded by the sheet4and the lower frame2is depressurized and the front surface6aof the molded substrate6is covered with the sheet4.

Specifically, the sheet4is suctioned using a vacuum in a downwardly moving direction via the vent holes2bof the bottom panel22of the lower frame2. Accordingly, the air in the chamber2A is suctioned toward the bottom panel22, and the chamber2A is depressurized to reach a high degree of vacuum.

Then, in a state in which a depressurizing operation of the chamber2A is maintained, a suctioning operation of the sheet4is stopped, and a space between the upper hot plate3A and the sheet4is opened to the atmosphere. That is, the sheet4suctioned to the first heating surface3a1of the upper hot plate3A is heated to a predetermined temperature, and after a predetermined time elapses, vacuum suctioning of the vent holes32of the upper hot plate3A is stopped to stop a suctioning operation. Accordingly, since the space between the upper hot plate3A and the sheet4is opened to the atmosphere, a pressure difference is generated in the upper and lower spaces with the sheet4interposed therebetween. Accordingly, the sheet4softened by the heating is separated from the first heating surface3a1of the upper hot plate3A and moves toward the bottom panel22(the molded substrate6) side. Then, the sheet4is closely pressed to cover the front surface6aof the molded substrate6, and covered and adhered onto the front surface6aof the molded substrate6. After that, trimming of the sheet4is performed by cutting the covered sheet4along an appropriate cut-off line using a cutting tool.

Further, when the space between the upper hot plate3A and the sheet4is exposed to the atmosphere, the compressed air may be ejected from the vent holes32of the upper hot plate3A to pressurize the space between the sheet4and the first heating surface3a1by switching the vacuum tank connected to the upper hot plate3A and the sheet4to the pressure tank.

Next, as shown inFIG. 9, a ninth process of removing the thermoformed product6A thermoformed when the molded substrate6is coated with the sheet4from the substrate tool24is performed.

In the ninth process, the upper hot plate3A is moved upward, and the lower frame2is moved from the molding position P0in a direction of moving away from the upper hot plate3A and a horizontal direction when seen in plan view to be moved to the first retreat position P1(seeFIG. 2). Then, the thermoformed product6A is separated and removed from the substrate tool24at the first retreat position P1.

The thermoformed product6A is completed by the above-mentioned operations, and a series of molding operations for thermoforming a thermoformed product6A is terminated.

When a plurality of molded substrates6are covered with the sheet4and performing continuous thermoforming, in the arrangement shown inFIG. 9, the sheet end4gsupported by the sheet support section52is substituted with a new sheet end4e, and the processes from the above-mentioned first process to ninth process may be sequentially performed.

Next, actions of the thermoforming device and the thermoforming method will be described with reference to the accompanying drawings.

In the embodiment, as shown inFIG. 6, the upper surface4aside of the sheet4is heated by the first heating surface3a1of the upper hot plate3A, and the lower surface4bside is heated by the second heating surface3b1of the lower hot plate3B. For this reason, since both of the upper and lower surfaces4aand4bof the sheet4are simultaneously heated, a reduction in heating time can be achieved.

Then, after the sheet4is softened by the heating, the lower hot plate3B is moved in a lateral direction from a position below the upper hot plate3A to be retracted to the second retreat position P2. Accordingly, the entire front surface6aof the molded substrate6of the lower frame2can be uniformly covered with the sheet4.

In this way, since the upper hot plate3A and the lower hot plate3B are configured to simultaneously heat both of the upper and lower surfaces4aand4bof the sheet4, a temperature of the upper hot plate3A may be lowered to the heat the sheet4. For this reason, it is possible to prevent a surface roughness of the first heating surface3a1from being transferred to the upper surface4aof the sheet4due to heating of the upper hot plate3A. For this reason, a decrease in design properties of the front surface of the thermoformed product6A after thermoforming can be suppressed.

In addition, in the embodiment, since the sheet4can be heated from the lower surface4bside of the sheet4, to which an adhesive agent is adhered, by the lower hot plate3B, the adhesive agent can be sufficiently softened. For this reason, an adhesive strength of the sheet adhered to the molded substrate6can be improved.

Further, in the embodiment, since both of the upper and lower surfaces4aand4bof the sheet4can be heated, the embodiment can also cope with a sheet having a large thickness. That is, even with a sheet having a thickness such that the lower surface4bof the sheet cannot be heated to a required temperature when heated by only the upper hot plate, the entire sheet can be die-molded by heating the lower surface4bof the sheet using the lower hot plate3B. Alternatively, the sheet can be heated to a sheet-softening temperature required for coating the entire sheet.

In addition, in the embodiment, since the upper hot plate3A and the lower hot plate3B are individually provided, it is possible to adjust temperature such that different temperatures are applied between the upper hot plate3A and the lower hot plate3B. For this reason, for example, the temperature of the lower surface4bof the sheet can be made higher than the upper surface4aof the sheet. For this reason, transfer to the upper surface4aof the sheet due to a high temperature of the upper hot plate3A can be prevented, and the adhesive agent on the lower surface4bof the sheet can be sufficiently softened due to a high heating temperature of the lower hot plate3B.

Accordingly, according to conditions of the sheet4such as a material, a thickness dimension, or the like, of the sheet4, appropriate heating to the sheet4can be performed, and a quality of the thermoformed product6A can be improved.

In addition, in the embodiment, the upper hot plate3A is configured such that the sheet4can be suctioned to and contacted with the first heating surface3a1to be heated. Meanwhile, the lower hot plate3B is configured to heat the lower surface4bof the sheet using radiant heat from the second heating surface3b1. For this reason, both of the upper and lower surfaces4aand4bof the sheet4can be heated by having the lower hot plate3B which has a simple structure including, for example, only a heater configured to heat the second heating surface3b1.

In addition, in the embodiment, during heating of the sheet4, the lower frame2can be retracted from the molding position P0to dispose the lower hot plate3B at the molding position P0. Then, after termination of the heating of the lower hot plate3B, the lower hot plate3B can be retracted from the molding position P0and the lower frame2can be disposed at the molding position P0to cover the molded substrate with the sheet4. For this reason, since the lower hot plate3B and the lower frame2can be switched alternately at the molding position P0, a height of the entire thermoforming device1can be suppressed.

In the thermoforming device and the thermoforming method according to the above-mentioned embodiment, a reduction in heating time of the sheet4can be achieved, and improvement of design properties of the thermoformed product6A can be achieved.

Hereinabove, while the thermoforming device and the thermoforming method according to the embodiment of the present invention have been described, the present invention is not limited to the embodiment and may be appropriately changed without departing from the scope of the present invention.

For example, while the upper hot plate3A is configured to move vertically in the above-mentioned embodiment, the embodiment is not limited thereto, and the lower frame2and the upper hot plate3A may relatively approach each other in the vertical direction. In addition, the position of the upper hot plate3A may be fixed, and the lower frame2may be provided to be vertically movable with respect to the upper hot plate3A. Alternatively, each of the lower frame2and the upper hot plate3A may be configured to be movable in the vertical direction. Accordingly, the position of the lower frame2is not limited thereto, and during thermoforming, the upper hot plate3A and the lower frame2may be provided to overlap each other when seen in plan view.

In addition, while heating by the upper hot plate3A and the lower hot plate3B are simultaneously performed in the thermoforming method according to the above-mentioned embodiment, a timing of the above-mentioned heating is not limited. The timing of heating by the upper hot plate3A and the lower hot plate3B may be changed. For example, heating by the lower hot plate3B can be performed before heating by the upper hot plate3A. On the other hand, heating by the lower hot plate3B may be performed after heating by the upper hot plate3A. The timings of heating by the upper hot plate3A and the lower hot plate3B can be set according to conditions such as a material and a thickness of the sheet4, a type of an adhesive agent, a material of the molded substrate6, and on the like. For this reason, the heating temperature can be accurately adjusted by providing the hot plates3A and3B above and below the sheet4.

In addition, a protective film may be formed on the adhering surface (the lower surface4b) of the sheet4to which an adhesive agent is attached. In this case, the protective film is peeled off simultaneously with or immediately before the supply of the sheet4to the heating surface of the hot plate3using the sheet transport apparatus5.

Further, in the above-mentioned embodiment, the lower frame2is configured to move between the first retreat position P1and the molding position P0in the lateral direction (the arrow D3direction shown inFIG. 2). However, the lower frame2is not limited to moving with respect to the molding position P0in the lateral direction. For example, the first retreat position P1may be an appropriate position to which the lower frame2is moved below the molding position P0, and a position at which the molded substrate6is attached to or detached from the bottom panel22(a base) in the lower frame2.

Further, while the above-mentioned embodiment is applied to the thermoforming method in which the sheet4is coated and adhered to the molded substrate6, the embodiment is not limited to the case of such lamination molding and may include a case in which a carrier film on the uppermost layer of the sheet is peeled off through trimless transfer and only a decorative layer (corresponding to the sheet of the present invention) is transferred to the molded substrate.

Further, while the above-mentioned embodiment is applied to the thermoforming method of covering the molded substrate6with the sheet4softened by the hot plate3, the embodiment is not limited to this sheet covering. For example, it is also possible to form a thermoformed product using the sheet4softened by heating of the hot plate3as a target of a die-mold configured to use the substrate tool24as a mold. Also in the case of this die-mold, the thermoforming method can be performed using the same method as that of the above-mentioned embodiment.

Furthermore, the method of supplying the sheet4to the heating surface is not limited to the sheet transport apparatus5using a roll sheet wound in a roll shape like the above-mentioned embodiment and a sheet transport apparatus having another configuration may be used. For example, the embodiment may be applied to a method of using a sheet transport apparatus configured such that a sheet-accommodating section configured to accommodate a plurality of cut sheets of a type previously cut to a predetermined size is provided, and a plurality of cut sheets accommodated in the sheet-accommodating section are unloaded one by one and supplied in an extending direction (i.e., the unwinding direction D1) of the heating surfaces3a1and3b1of the hot plate3.

In addition, shapes and sizes of the lower frame2(the stand23, the substrate tool24, or the like), the upper hot plate3A and the lower hot plate3B, and configurations of a cutting means or the like of a sheet can be appropriately set.

Further, a trimming process may be performed at the same time as the molding like in the above-mentioned embodiment, or may be performed in another process after molding.

In addition, the components in the above-mentioned embodiment can be appropriately substituted with known components without departing from the scope of the present invention.

DESCRIPTION OF REFERENCE SIGNS

3A Upper hot plate

3B Lower hot plate

3a1First heating surface

3b1Second heating surface

21aFrame upper edge portion

P1First retreat position

P2Second retreat position