JP2020196204A - Thermoforming apparatus and thermoforming method - Google Patents

Abstract

To provide a thermoforming apparatus and a thermoforming method capable of suppressing the extension of a sheet at the time of thermoforming that may cause manufacturing defects or appearance defects of a thermoformed product.SOLUTION: A thermoforming apparatus 1 shapes a heated sheet S1 with an upper mold 2 and a lower mold 3. In the thermoforming apparatus 1 comprising: a sheet jig 4 for holding the sheet S1; and a carrying device 51 for carrying the sheet into the thermoforming apparatus 1 and carrying it out in a state in which the sheet jig 4 holds the sheet S1, the sheet jig 4 is provided with a sandwiching member 42 for sandwiching the outer periphery of the sheet S1; the sandwiching member 42 is arranged in the lower mold 3 when the sheet S1 is carried into the thermoforming apparatus 1; and a releasing mechanism (a lower end surface 22a, a holding panel 41, and an installation part 36) is provided for releasing the sandwiching of the sheet S1 when the upper mold 2 and the lower mold 3 come into contact in a state in which the sandwiching member 42 is arranged in the lower mold 3.SELECTED DRAWING: Figure 1

Description

The present invention is a thermoforming apparatus that shapes a heated sheet by means of an upper die and a lower die, and is a thermoforming device for holding a sheet and a state in which the sheet jig holds the sheet. A thermoforming method for shaping a heated sheet by a thermoforming device having a transfer device to be carried in and out of the device, and a thermoforming device including an upper die and a lower die. The present invention relates to a thermoforming method in which a sheet jig is carried into a thermoforming apparatus while holding a sheet, the sheet is thermoformed, and then the sheet is carried out of the thermoforming apparatus.

Conventionally, when coating the surface of a smartphone case, the surface of the smartphone case is coated with the coating member by thermoforming a heated sheet-shaped coating member. For example, it has a base jig for holding a molded base material (for example, a case of a smartphone) and a hot plate for heating a sheet (for example, a sheet-shaped coating member) as disclosed in Patent Document 1, and heats the sheet. A thermoforming apparatus capable of coating the surface of the molded base material with the formed sheet is used.

As shown in FIGS. 8, 9, and 10, the thermoforming apparatus 100 disclosed in Patent Document 1 has an upper mold 110 that can be moved up and down in the drawing by an elevating means (not shown) and a fixed side. It consists of a lower mold 120.
Then, as shown in FIG. 9, the upper mold 110 and the lower mold 120 come into contact with each other via the sheet S2, so that the upper frame 111 and the lower frame 121 form a molding chamber 101, and the inside of the molding chamber 101 is formed. In, the sheet S2 is coated on the molded base material U2 held by the lower base material 122.

Explaining the process of coating the sheet S2 on the molded base material U2, first, as shown in FIG. 8, the sheet S2 whose outer circumference is sandwiched by the sheet jig 130 or the like is placed in the lower mold 120 with the molded base material U2. (For example, the case of a smartphone) is conveyed to the thermoforming apparatus 100 held and arranged so as to be in contact with the upper end surface 121a of the lower frame 121.

Next, as shown in FIG. 9, the entire upper mold 110 is lowered so that the lower end surface 111a of the upper frame 111 abuts on the upper end surface 121a of the lower frame 121 via the sheet S2. As a result, the outer peripheral portion of the sheet S2 is fixed in a state of being sandwiched between the lower end surface 111a of the upper frame 111 and the upper end surface 121a of the lower frame 121. At this time, the molding chamber 101 is vertically partitioned by the sheet S2, the upper side of the sheet S2 is the pressurizing chamber 101A, and the lower mold of the sheet S2 is the decompression chamber 101B.

Then, the decompression chamber 101B is connected to a vacuum pump (not shown), and by opening the vacuum pump, the decompression chamber 101B is evacuated and decompressed. On the other hand, the pressurizing chamber 101A is connected to a compressor (not shown), and compressed air is supplied to the pressurizing chamber 101A by the compressor to bring the pressurized chamber 101A into a pressurized state.

The molding base material U2 is raised by raising the lower base material 122 while the pressure reducing chamber 101B is depressurized and the pressure chamber 101A is pressurized. Then, as shown in FIG. 10, the softened sheet S2 is attracted to the outer surface of the molding base material U2, and the sheet S2 is covered without gaps over the entire surface of the molding base material U2.

Japanese Patent No. 5957131

However, the above-mentioned prior art has the following problems.
In the conventional thermoforming apparatus 100, the outer peripheral portion of the sheet S2 is sandwiched between the lower end surface 111a of the upper frame 111 and the upper end surface 121a of the lower frame 121, and thermoforming is performed in a fixed state. With the outer peripheral portion of the sheet S2 fixed, the flat sheet S2 is formed into a convex shape following the shape of the molding base material U2, so that the sheet S2 is formed by the sandwiched portion and the molding base material U2. Is pulled and stretches. When the sheet S2 is stretched, for example, when the sheet S2 is hard-coated, the sheet S2 is difficult to stretch and may be cracked.

Further, if thermoforming is performed while the sheet S2 is sandwiched, there is a possibility that the elongation generated in the sheet S2 becomes non-uniform. When the sheet S2 is made of polycarbonate, the elongation of the sheet S2 becomes non-uniform, which causes a phase difference and causes an interference color (so-called rainbow unevenness). If interference color occurs, it may lead to poor appearance of the product.

The present invention is for solving the above-mentioned problems, and is a thermoforming apparatus and a thermoforming apparatus capable of suppressing elongation of a sheet during thermoforming, which causes a manufacturing defect or an appearance defect of a thermoformed product. The purpose is to provide a method.

In order to solve the above problems, the thermoforming apparatus and the thermoforming method of the present invention have the following configurations.
(1) A thermoforming apparatus that shapes a heated sheet by means of an upper die and a lower die, and is a thermoforming apparatus for holding a sheet and a thermoforming apparatus in a state where the sheet jig holds a sheet. In a thermoforming apparatus having a transfer device for carrying in and out, the sheet jig is provided with a holding member for sandwiching the outer periphery of the sheet, and when the sheet is carried into the thermoforming device, the sandwiching member is provided. It is characterized by being arranged in the lower mold and having a release mechanism for releasing the sandwiching of the sheet when the upper mold and the lower mold come into contact with each other in a state where the holding member is arranged in the lower mold. To do.

(2) In the thermoforming apparatus according to (1), the lower mold is provided with a shaping mold for shaping the sheet, and the shaping is performed in a state where the sheet is pressurized by compressed air from the upper mold side. That is, the upper mold is characterized by having a guide portion on the entire inner circumference of the holding member, which faces the surface of the sheet to be pressed with a slight gap.

(3) A thermoforming method in which a heated sheet is shaped by a thermoforming apparatus provided with an upper mold and a lower mold, and the sheet jig is carried into the thermoforming apparatus while holding the sheet. In the thermoforming method in which the sheet is thermoformed and then carried out of the thermoforming apparatus, when the sheet is carried into the thermoforming apparatus, the outer periphery is sandwiched by the sandwiching member, and the upper die and the lower die are held together. It is characterized in that the shaping is performed in a state where the sandwiching of the sheet is released at the time of contact.

The thermoforming apparatus and thermoforming method of the present invention have the following actions and effects by having the above configuration.
According to the thermoforming apparatus according to (1), it is possible to suppress the elongation of the sheet during thermoforming, which causes a manufacturing defect or an appearance defect of the thermoformed product.
The sheet jig includes a sandwiching member that sandwiches the outer periphery of the sheet, and the sheet is carried into the thermoforming apparatus in a sandwiched state by the conveying device. However, since the holding member is arranged in the lower mold, the outer peripheral portion of the sheet is not fixed by the lower frame or the upper frame as in the conventional thermoforming apparatus. Further, the thermoforming apparatus is provided with a release mechanism for releasing the sandwiching of the sheet when the upper mold and the lower mold are in contact with each other, and the shaping by thermoforming is a state in which the upper mold and the lower mold are in contact with each other. Therefore, the thermoforming of the sheet is performed in a state where the sandwiching of the outer peripheral portion is released. By performing the thermoforming of the sheet in a state where the outer peripheral portion is released from being sandwiched, the sheet is not pulled during the thermoforming, and the possibility of stretching is reduced. If the risk of stretching is reduced, the risk of cracking due to stretching is reduced even if the sheet is hard-coated. Further, even when the sheet is made of polycarbonate, an interference color (so-called rainbow unevenness) is generated at a portion where the sheet is stretched by thermoforming, and the possibility of leading to a defective product appearance is reduced.

According to the thermoforming apparatus according to (2), thermoforming can be performed with high accuracy.
When performing thermoforming, the sheet is compressed from the direction opposite to the shaping mold side in order to ensure that the sheet adheres to the shaping mold (for example, a molding base material such as a smartphone case, a mold, etc.). Pressurized by air. However, in the present invention, since thermoforming is performed in a state where the sheet is released from being sandwiched by the sandwiching member, when the sheet is pressurized by compressed air, the compressed air enters between the sheet and the shaping mold. Then, the sheet may be turned up and may not adhere to the shaping mold. If the sheet does not adhere to the shaping mold, thermoforming cannot be performed with high accuracy, which may lead to molding defects of the thermoformed product.

Therefore, as in the present invention, the upper mold has a guide portion, and the guide portion faces the surface of the sheet to be pressurized with a small gap, so that the guide portion is pressurized by compressed air. Even if the seat is to be turned up, the guide portion regulates the movement of the seat to be turned up, and the risk of the seat being turned up is reduced. If the risk of the sheet turning up is reduced, the sheet will surely adhere to the shaping mold, and thermoforming can be performed with high accuracy.

According to the thermoforming method described in (3), it is possible to suppress the elongation of the sheet during thermoforming, which causes a manufacturing defect or an appearance defect of the thermoformed product.
When the sheet is carried into the thermoforming apparatus, the outer circumference is sandwiched by the sandwiching member. However, when the upper mold and the lower mold come into contact with each other, the sheet is released from being sandwiched, and thermoforming is performed in a state where the sheet is released from being sandwiched. Therefore, the sheet is not pulled during thermoforming and stretches. Is reduced. If the risk of stretching is reduced, the risk of cracking due to stretching is reduced even if the sheet is hard-coated. Further, even when the sheet is made of polycarbonate, an interference color (so-called rainbow unevenness) is generated at a portion where the sheet is stretched by thermoforming, and the possibility of leading to a defective product appearance is reduced.

It is a figure which shows the state which arranged the sheet held by the sheet jig in the thermoforming apparatus in the state which the upper die and the lower die are open. It is a figure which shows the state which a softened sheet is arranged in a thermoforming apparatus, and then the upper die and the lower die come into contact with each other through a sheet jig, and the die is closed. It is a figure which shows the state which the lower base material moved upward after the upper mold and the lower mold were closed, and the coating of a sheet on a molded base material was started. It is a figure which shows the state which the lower base material reached the upper limit position, and the sheet was coated on the molded base material. It is a figure which shows the state which the sheet held by a sheet jig is heated by a heater. It is a figure which shows the top view of the sheet jig of FIG. (A) is an enlarged view of a portion of the sheet jig holding the sheet before closing the mold in a state where the sheet is arranged in the thermoforming apparatus. (B) is an enlarged view of a portion of the sheet jig for sandwiching the sheet when the mold is closed, and represents a state in which the sandwiching of the sheet is released. It is a figure explaining the prior art, and is the figure which shows the state which the sheet held by the sheet jig is arranged in the thermoforming apparatus. It is a figure explaining the prior art, and is the figure which shows the state which the upper die and the lower die are in contact with each other through a sheet, and the die is closed. It is a figure explaining the prior art, and is the figure which shows the state which the sheet was coated on the molded base material.

An embodiment of the thermoforming apparatus 1 of the present invention will be described in detail with reference to the drawings.
In the thermoforming apparatus 1 of the present embodiment, the sheet S1 which has been heated to the glass transition point by the heater 50 (see FIG. 5) and softened is carried into the thermoforming apparatus 1 by the transport device 51 and inside the thermoforming apparatus 1. It is an apparatus for covering the surface of the molding base material U1 arranged in.
The thermoforming apparatus 1 includes an upper mold 2 that can be moved up and down in FIG. 1 by an elevating means (not shown) and a lower mold 3 that is a fixed side. The upper mold 2 and the lower mold 3 are brought into contact with each other via the sheet jig 4, which will be described later, to form a molding chamber 11 (see FIG. 2), which is held by the lower base material 33 in the molding chamber 11. The sheet S1 is coated on the molded base material U1.

Note that FIG. 1 shows a state in which the sheet S1 held by the sheet jig 4 is arranged in the thermoforming apparatus 1 in which the upper mold 2 and the lower mold 3 are open, and the molding base material U1 is covered with the sheet S1. The figure of the state before the jig is shown. FIG. 2 shows a state in which the softened sheet S1 is placed in the thermoforming apparatus 1 and then the upper mold 2 and the lower mold 3 are in contact with each other via the sheet jig 4 and the mold is closed. FIG. 3 shows a state in which the lower base material 33 moves upward after the upper mold 2 and the lower mold 3 are closed, and the coating of the sheet S1 on the molding base material U1 is started. .. FIG. 4 shows a state in which the lower base material 33 reaches the upper limit position and the sheet S1 is coated on the molded base material U1.

A thermoformed product is formed by coating the surface of a resin-made molding base material U1 with a sheet S1, and examples of the thermoformed product include a smartphone case and the like.

The molded base material U1 has a topped tubular shape. However, the shape is not limited to this, and as shown in FIG. 1, the height dimension is such that the molding base material U1 does not come into contact with the sheet S1 when the sheet S1 is installed in the thermoforming apparatus 1. There are no particular restrictions other than the setting required. Further, a thermoplastic resin such as a polypropylene resin or a polyethylene resin is applied to the material of the molding base material U1. However, the present invention is not limited to these, and it is also possible to adopt a material to which the adhesive layer can be applied, such as a thermosetting resin, iron, and stone.

The sheet S1 is not particularly limited as long as it exhibits flexibility and adhesiveness when heated and can be coated on the surface of the molded base material U1 when cooled. In the packaging terminology of JIS (Japanese Industrial Standards), a thin plate-shaped plastic material having a thickness of 250 μm or more is defined as a sheet, and a film-shaped plastic material having a thickness of less than 250 μm is defined as a film. However, in the present embodiment, the thickness of the sheet S1 is not particularly specified, and it may be specified as a film in JIS.

Next, the upper mold 2 will be described.
The upper mold 2 includes an upper base 21, an upper frame 22, and a temperature control portion 23. The upper base 21 has a rectangular flat plate shape, and an upper frame 22 is erected on the lower surface of the upper base 21 in FIG.

The upper frame 22 is fixed to the upper base 21 by bolts. An O-ring 24 for keeping the molding chamber 11 airtight when the upper mold 2 and the lower mold 3 are closed is attached to the lower end surface 22a of the upper frame 22 in FIG.

A temperature control portion 23 fixed to the upper base 21 by the connecting rod 25 is arranged so as to be surrounded by the upper frame 22. The temperature control unit 23 has a built-in temperature control heater 26 and adjusts the temperature of the thermoforming apparatus 1.
Further, a guide portion 27 is arranged on the lower surface of the temperature control portion 23, and the guide portion 27 is with the upper surface of the sheet S1 in the drawing when the upper mold 2 and the lower mold 3 are closed. They are opposed to each other with a minute gap 37 (see FIG. 7B) (details will be described later).

A plurality of ventilation holes (not shown) are formed on the lower surface of the temperature control portion 23 at predetermined intervals. A compressor (not shown) is connected to these vents. The compressor can supply compressed air to the pressurizing chamber 11A, which will be described later, through the ventilation holes, and can bring the pressurizing chamber 11A into a pressurized state.

Next, the lower mold 3 will be described.
The lower mold 3 includes a lower base 31, a lower frame 32 having a recess 32b capable of accommodating the molding base material U1, and a lower base material 33 holding the molding base material U1 from the lower direction in FIG.

A lower frame 32 is fixed to the upper surface of the lower base 31. Further, an O-ring 34 for keeping the molding chamber 11 airtight when the upper mold 2 and the lower mold 3 are closed is attached to the upper end surface 32a of the lower frame 32 in FIG. In the recess 32b of the lower frame 32, a lower base material 33 that moves up and down by the elevating device 35 is arranged. The vertical movement of the lower base material 33 is performed between the lower limit position shown in FIG. 1 and the upper limit position shown in FIG.

A vacuum vent (not shown) penetrating the lower frame 32 is formed on the bottom surface of the recess 32b of the lower frame 32. A vacuum pump (not shown) is connected to this vacuum vent. There is no limit to the number of vacuum vents, and at least one may be formed. The vacuum pump can evacuate the pressure reducing chamber 11B, which will be described later, through the vacuum ventilation holes. Further, on the bottom surface of the recess 32b of the lower frame 32, an installation portion 36 for installing the bolts 43 constituting the sheet jig 4 is arranged.

Next, the sheet jig 4 will be described.
The sheet jig 4 is a jig for holding the sheet S1 when it is heated by the heater 50, when it is carried into the thermoforming device 1, and when it is carried out from the thermoforming device 1.

The sheet jig 4 is connected to the transfer device 51, and the transfer device 51 moves the sheet jig 4. When the transfer device 51 moves the sheet jig 4, the sheet S1 heated and softened by the heater 50 is carried into the thermoforming device 1, and the thermoforming device 1 of the sheet S1 has been thermoformed. It is carried out.

As shown in FIG. 5, the sheet jig 4 includes a holding panel 41 and holding members 42A and 42B.
The holding panel 41 has a flat plate shape and has a through hole 41a in the central portion. During thermoforming, when the lower base material 33 is raised by the elevating device 35, the molding base material is held by the lower base material 33. U1 passes through the through hole 41a to form the sheet S1.

The sandwiching members 42A and 42B are arranged so as to face the upper surface side of the holding panel 41 and are coupled to the bolt 43. As shown in FIG. 6, a pair of sandwiching members 42A and a pair of sandwiching members 42B are arranged so that the outer periphery of the sheet S1 can be sandwiched from all sides, and the sandwiching member 42A sandwiches the sheet S1 in the lateral direction. However, the sandwiching member 42B sandwiches the sheet S1 in the longitudinal direction. The sandwiching member 42A and the sandwiching member 42B have the same cross-sectional shape. Hereinafter, the holding member 42A and the holding member 42B are collectively referred to as a holding member 42.

The bolt 43 penetrates the holding panel 41 so as to be slidable in the vertical direction, and is inserted into the spring 44 on the lower surface side of the holding panel 41.
Since the spring 44 is compressed by the spring receiving portion 45 that is coupled to the bolt 43 and the lower surface of the holding panel 41, the bolt 43 is always urged downward in the drawing. Since the bolt 43 is urged downward, the sheet S1 can be sandwiched between the sandwiching member 42 coupled to the bolt 43 and the upper surface side of the holding panel 41.

The sheet S1 is heated by the heater 50 in a state of being sandwiched between the sandwiching member 42 and the upper surface side of the holding panel 41, and then is carried into the thermoforming apparatus 1 by the conveying device 51. As shown in FIG. 1, when the sheet S1 is installed in the thermoforming apparatus 1, the sheet S1 is in a state of being sandwiched between the holding panel 41 and the sandwiching member 42. However, when the upper mold 2 and the lower mold 3 come into contact with each other via the sheet jig 4, specifically, the lower end surface 22a of the upper frame 22 and the upper end surface 32a of the lower frame 32 come into contact with the sheet jig 4 (holding panel 41). ), The sandwiching of the sheet S1 is released.

Here, the sandwiching of the sheet S1 is released as follows.
When the softened sheet S1 is arranged in the thermoforming apparatus 1, as shown in FIG. 7A, the softened sheet S1 is arranged so that the lower end portion of the bolt 43 is in contact with the upper surface of the installation portion 36. At this time, there is a predetermined gap between the lower surface of the holding panel 41 and the upper end surface 32a of the lower frame 32.

In this state, when the upper die 2 is operated downward, the lower end surface 22a of the upper frame 22 presses the upper surface of the holding panel 41 and pushes it down. Since the bolt 43 is in contact with the installation portion 36 and its movement in the downward direction is restricted, the spring 44 is also restricted in the downward direction by the spring receiving portion 45 coupled to the bolt 43. Therefore, the holding panel 41 pushed down to the lower end surface 22a of the upper frame 22 lowers while compressing the spring 44.

Since the downward movement of the bolt 43 is restricted, the position of the holding member 42 coupled to the bolt 43 does not change. Therefore, when the holding panel 41 is lowered, the upper surface of the holding panel 41 and the upper surface of the holding panel 41 The sandwiching member 42 is separated from the pinching member 42, and the sandwiching of the sheet S1 is released as shown in FIG. 7B.
As described above, the lower end surface 22a of the upper frame 22, the installation portion 36 provided on the lower frame 32, and the holding panel 41 of the sheet jig 4 constitute a releasing mechanism for releasing the sandwiching of the sheet S1. Since the upper mold 2 and the lower mold 3 are closed, the sandwiching of the sheet S1 is released, so that thermoforming can be performed in a state where the sandwiching of the sheet S1 is released.

Here, the molding chamber 11 formed by closing the upper mold 2 and the lower mold 3 is vertically partitioned by the sheet jig 4 and the sheet S1, and the upper side of the sheet jig 4 and the sheet S1 is pressurized. The lower mold of the chamber 11A, the sheet jig 4 and the sheet S1 becomes the decompression chamber 11B.

As described above, the compressed air can be supplied from the compressor to the pressurizing chamber 11A by the ventilation holes provided on the lower surface of the temperature control unit 23, and the vacuum ventilation holes provided on the bottom surface of the recess 32b of the lower frame 32. , The decompression chamber 11B can be evacuated with a vacuum pump to reduce the pressure. Therefore, the side of the sheet S1 opposite to the molding base material U1 is pressurized, and the molding base material U1 side of the sheet S1 is depressurized, so that the sheet S1 can be brought into close contact with the molding base material U1 during thermoforming.

Further, when the upper mold 2 and the lower mold 3 are closed, as shown in FIG. 7B, the guide portion 27 is placed on the upper surface of the sheet S1 in the drawing (that is, in the vicinity of the inner circumference of the holding member 42). , The surface on the side pressurized by compressed air) and facing each other with a minute gap 37. The minute gap 37 referred to here is a gap that can regulate the movement of the seat S1 by interfering with the seat S1 when the seat S1 tries to move in the vertical direction in the drawing.

More specifically, the sheet S1 is pressurized by compressed air from the direction opposite to the side of the molding base material U1. However, in the thermoforming apparatus 1 according to the present embodiment, thermoforming is performed in a state where the sandwiching member 42 releases the sandwiching of the sheet S1. Therefore, when the sheet S1 is pressurized by the compressed air, the compressed air is released into the sheet. There is a possibility that the sheet S1 may be turned up by entering between S1 and the molding base material U1 and may not adhere to the molding base material U1. If the sheet S1 does not adhere to the molding base material U1, it will lead to molding defects of the thermoformed product, and thermoforming cannot be performed with high accuracy.

However, in the thermoforming apparatus 1 according to the present embodiment, the upper mold 2 has a guide portion 27, and the guide portion 27 faces the surface of the sheet S1 on the pressurized side with a minute gap 37. Therefore, even if the sheet S1 tries to turn up when pressurized by the compressed air, the sheet S1 trying to turn up and the guide portion 27 interfere with each other. Since the movement of the sheet S1 to be turned up is restricted by the interference between the sheet S1 to be turned up and the guide portion 27, the possibility of the sheet S1 to be turned up is reduced. If the possibility that the sheet S1 is turned up is reduced, the sheet S1 can be reliably adhered to the molding base material U1 and thermoforming can be performed with high accuracy.

The guide unit 27 only needs to be able to regulate the movement of the seat S1 when the seat S1 tries to move in the vertical direction in the drawing, so that the seat S1 can freely move in the horizontal direction in the drawing. It may be something that is lightly touched. The reason for allowing the sheet S1 to move freely in the left-right direction is that if the movement of the sheet S1 in the left-right direction is restricted, the outer periphery of the sheet S1 is sandwiched and fixed in the same manner as the conventional thermoforming apparatus 100. This is because it may lead to a manufacturing defect or an appearance defect of the thermoformed product.

When the thermoforming is completed and the upper mold 2 and the lower mold 3 are released from each other, the force that the lower end surface 22a of the upper frame 22 is holding the upper surface of the holding panel 41 disappears, and the elastic force of the compressed spring 44 causes the force. , The holding panel 41 returns to its original position. Then, the sheet S1 is again sandwiched between the sandwiching member 42 and the holding panel 41. Since the sheet S1 is sandwiched again, if the transfer device 51 moves the sheet jig 4, the sheet S1 can be carried out from the thermoforming device 1.

The position where the sheet S1 is sandwiched again varies from the position where the sheet S1 was sandwiched before thermoforming to the outer peripheral side of the sheet S1. This is because the sheet S1 is thermoformed without being sandwiched, so that the sheet S1 is less likely to be stretched by the thermoforming, and the S1 is extruded upward by the molding base material U1. This is because the end portion S1a of the sheet S1 moves from the center of the sheet S1.

Next, a thermoforming method using the thermoforming apparatus 1 will be described. The thermoforming method of the present embodiment is a method for shaping the sheet S1 softened by heating and coating it on the molding base material U1. Specifically, thermoforming is performed by the following steps.

First, as shown in FIG. 5, the sheet S1 is heated by the heater 50 until it reaches the glass transition point to soften it. In the present embodiment, the sheet S1 is heated from above and below by the pair of heaters 50, but the sheet S1 may be heated from either the upper direction or the lower direction.

Next, the softened sheet S1 is carried into the thermoforming device 1 by the transport device 51 in a state of being sandwiched between the sheet jigs 4, and is arranged in the thermoforming device 1 as shown in FIG. At this time, the lower end of the bolt 43 of the sheet jig 4 is arranged so as to come into contact with the installation portion 36. When the sheet S1 is carried into the thermoforming apparatus 1, the thermoforming apparatus 1 is in a state in which the upper mold 2 and the lower mold 3 are released from each other, and the molding base material U1 is held in the lower base material 33. is there. Further, the lower base material 33 is in the lower limit position, and the molding base material U1 is in a state where it does not come into contact with the sheet S1 installed in the thermoforming apparatus 1.

Next, the upper mold 2 is operated downward, and as shown in FIG. 2, the upper frame 22 and the lower frame 32 are brought into contact with each other via the sheet jig 4, and the upper mold 2 and the lower mold 3 are closed. To do. When the mold is closed, the sheet S1 is released from being sandwiched by the sheet jig 4, and the guide portion 27 faces the upper surface of the sheet S1 in the drawing with a slight gap 37.
Further, when the mold is closed, the upper surface of the holding panel 41 and the lower end surface 22a of the upper frame 22 compress the O-ring 24, and the pressurizing chamber 11A in the molding chamber 11 is kept airtight. Further, the O-ring 34 is compressed by the lower surface of the holding panel 41 and the upper end surface 32a of the lower frame 32, and the decompression chamber 11B in the molding chamber 11 is kept airtight.

Next, the pressurization of the pressurizing chamber 11A by the compressor and the depressurization of the decompression chamber 11B by the vacuum pump are started, and the lower base material 33 is raised by the elevating device 35 to bring the molded base material U1 into contact with the sheet S1. .. Since the sheet S1 exhibits flexibility by softening, it is shaped along the surface shape of the molding base material U1 as shown in FIG. At this time, since the pressurization chamber 11A and the depressurization chamber 11B are performed, the surface of the molding base material U1 and the sheet S1 are in close contact with each other without any gap.

Then, as shown in FIG. 4, when the rising lower base material 33 reaches the upper limit position, the entire surface of the molding base material U1 is covered with the sheet S1. Since the sheet S1 exhibits adhesiveness by softening, it is adhered to the surface of the molding base material U1.
Through the above steps, a thermoformed product made of the molding base material U1 and the sheet S1 is completed, and a series of thermoforming operations is completed.

As described above, according to the thermoforming apparatus 1 of the present embodiment,
(1) A thermoforming apparatus 1 that shapes the heated sheet S1 by the upper mold 2 and the lower mold 3, and the sheet jig 4 for holding the sheet S1 and the sheet jig 4 hold the sheet S1. In the thermoforming apparatus 1 having a thermoforming apparatus 51 that carries in and out of the thermoforming apparatus 1 in a held state, the sheet jig 4 includes a sandwiching member 42 that sandwiches the outer periphery of the sheet S1. However, when it is carried into the thermoforming apparatus 1, the holding member 42 is arranged in the lower mold 3, and in a state where the holding member 42 is arranged in the lower mold 3, the upper mold 2 and the lower mold 3 are arranged. Is provided with a release mechanism (lower end surface 22a, holding panel 41, installation portion 36) for releasing the sandwiching of the sheet S1 when the sheet S1 is brought into contact with the thermoformed product. It is possible to suppress the elongation of the sheet S1 during such thermoforming.

The sheet jig 4 includes a sandwiching member 42 that sandwiches the outer periphery of the sheet S1, and the sheet S1 is carried into the thermoforming apparatus 1 in a sandwiched state by the transport device 51. However, since the holding member 42 is arranged in the lower mold 3, the outer peripheral portion of the sheet S1 is not fixed by the lower frame 32 or the upper frame 22 unlike the conventional thermoforming apparatus 100. Further, the thermoforming apparatus 1 is provided with a release mechanism (lower end surface 22a, holding panel 41, installation portion 36) for releasing the sandwiching of the sheet S1 when the upper mold 2 and the lower mold 3 come into contact with each other. Since the shaping by molding is performed in a state where the upper mold 2 and the lower mold 3 are in contact with each other, the thermoforming of the sheet S1 is performed in a state where the outer peripheral portion is released from being sandwiched. Since the thermoforming of the sheet S1 is performed in a state where the outer peripheral portion is released from being sandwiched, the sheet S1 is not pulled during the thermoforming, and the possibility of stretching is reduced. If the possibility of stretching is reduced, the risk of cracking due to stretching is reduced even when the sheet S1 is hard-coated. Further, even when the sheet is made of polycarbonate, an interference color (so-called rainbow unevenness) is generated at a portion where the sheet is stretched by thermoforming, and the possibility of leading to a defective product appearance is reduced.

(2) In the thermoforming apparatus 1 described in (1), the lower mold 3 is provided with a shaping mold (molding base material U1) for shaping the sheet S1, and the shaping is performed by placing the sheet S1 on the upper mold 2 side. The upper mold 2 has a guide portion 27 that faces the surface of the sheet S1 on the side to be pressurized with a minute gap 37 on the entire inner circumference of the sandwiching member 42, which is performed in a state of being pressurized by compressed air. Since it is characterized by the fact that it can be thermoformed with high accuracy.

In order to ensure that the sheet S1 is in close contact with the shaping mold (molding base material U1) during thermoforming, the sheet S1 is subjected to compressed air from the direction opposite to the side of the shaping mold (molding base material U1). It is pressurized. However, in the present invention, since thermoforming is performed in a state where the sandwiching member 42 is released from sandwiching the sheet S1, when the sheet S1 is pressurized by the compressed air, the compressed air is shaped with the sheet S1. The sheet S1 may be turned up due to being inserted between the molding base materials U1) and may not adhere to the shaping mold (molding base material U1). If the sheet S1 does not adhere to the shaping mold (molding base material U1), thermoforming cannot be performed with high accuracy, which may lead to molding defects of the thermoformed product.

Therefore, as in the present invention, the upper die 2 has a guide portion 27, and the guide portion 27 faces the surface of the sheet S1 on the pressurized side with a minute gap 37. Even if the sheet S1 tries to turn up when pressurized by the compressed air, the guide portion 27 regulates the movement of the sheet S1 trying to turn up, and the possibility of the sheet S1 turning up is reduced. If the possibility that the sheet S1 is turned up is reduced, the sheet S1 can be reliably adhered to the shaping mold (molding base material U1), and thermoforming can be performed with high accuracy.

(3) A thermoforming method for shaping a heated sheet S1 by a thermoforming apparatus 1 including an upper mold 2 and a lower mold 3, in which the sheet jig 4 holds the sheet S1. In the thermoforming method of carrying the sheet S1 into the apparatus 1 and then thermoforming the sheet S1 and then carrying it out of the thermoforming apparatus 1, when the sheet S1 is brought into the thermoforming apparatus 1, the outer periphery is sandwiched by the sandwiching member 42. The thermoformed product is characterized in that, when the upper mold 2 and the lower mold 3 come into contact with each other, the shaping (thermoforming) is performed in a state where the sheet S1 is released from being sandwiched. It is possible to suppress the elongation of the sheet S1 at the time of thermoforming, which causes a manufacturing defect or an appearance defect.

When the sheet S1 is carried into the thermoforming apparatus 1, the outer circumference of the sheet S1 is sandwiched by the sandwiching member 42. However, when the upper mold 2 and the lower mold 3 come into contact with each other, the sandwiching of the sheet S1 is released, and the thermoforming is performed in a state where the sandwiching of the sheet S1 is released, so that the sheet S1 is pulled during the thermoforming. There is no such thing, and the risk of elongation is reduced. If the possibility of stretching is reduced, the risk of cracking due to stretching is reduced even when the sheet S1 is hard-coated. Further, even when the sheet S1 is made of polycarbonate, an interference color (so-called rainbow unevenness) is generated at a portion where the sheet S1 is stretched by thermoforming, and the possibility of leading to a defective product appearance is reduced.

It should be noted that the present embodiment is merely an example and does not limit the present invention in any way. Therefore, as a matter of course, the present invention can be improved and modified in various ways without departing from the gist thereof.
For example, in the present embodiment, the sheet S1 softened by the heater 50 is coated on the molding base material U1, but the lower base material 33 is used as a mold and the sheet S1 softened by heating the heater 50 is used as a mold. It is also possible to shape it.

1 Thermoforming device 2 Upper mold 3 Lower mold 4 Sheet jig 22a Lower end surface (example of release mechanism)
41 Holding panel (example of release mechanism)
36 Installation part (example of release mechanism)
42 Holding member 51 Transport device S1 sheet

Claims (3)

A thermoforming apparatus that shapes a heated sheet by means of an upper mold and a lower mold, the sheet jig for holding the sheet, and the thermoforming in a state where the sheet jig holds the sheet. In a thermoforming apparatus having a transport device that carries in and out of the device.
The sheet jig includes a holding member that holds the outer circumference of the sheet.
When the sheet is carried into the thermoforming apparatus, the holding member is arranged in the lower mold.
When the upper mold and the lower mold come into contact with each other in a state where the holding member is arranged in the lower mold, a release mechanism for releasing the holding of the sheet is provided.
A thermoforming apparatus characterized by. In the thermoforming apparatus according to claim 1,
The lower mold includes a shaping mold that shapes the sheet.
The shaping is performed in a state where the sheet is pressurized by compressed air from the upper mold side.
The upper mold has a guide portion that faces the surface of the sheet to be pressed with a slight gap on the entire inner circumference of the sandwiching member.
A thermoforming apparatus characterized by. It is a thermoforming method in which a heated sheet is shaped by a thermoforming apparatus including an upper mold and a lower mold. The sheet is carried into the thermoforming apparatus while the sheet jig holds the sheet, and the sheet is carried into the thermoforming apparatus. In the thermoforming method of carrying out the thermoforming device to the outside of the thermoforming apparatus after thermoforming.
When the sheet is carried into the thermoforming apparatus, the outer circumference is sandwiched by the sandwiching member.
When the upper mold and the lower mold come into contact with each other, the shaping is performed in a state where the sheet is released from being sandwiched.
A thermoforming method characterized by.

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