Thermoforming device

Abstract

The present application is a thermoforming device (100) which performs mold shaping by heating a resin sheet (S) with a heating unit (110), wherein the heating unit (110) is arranged with a plurality of heaters (111) and has a first region (A1) and a second region (A2) of the heaters (111) corresponding to a convex portion (200a) of a mold (200), and a heating control unit is provided for the heating unit (110) to perform different power control in the first region (A1) and the second region (A2), and the heating control unit (250) can perform multi-stage heating control to set different heating conditions in a first heating stage and a second heating stage.

Description

Technical Field

[0001] This invention relates to a technique for thermoforming resin sheets, specifically a technique for improving molding accuracy by adjusting the heating conditions according to the location when heating resin sheets with a radiant heating device to form them. Background Technology

[0002] Thermoforming machines are used to mold softened resin sheets into food containers or blister packs. They are also used to manufacture various plastic products such as automotive parts, home appliances, and industrial pallets. In recent years, thermoforming machines have also been used in applications such as transferring patterns, bonding resin sheets to the outer surface of molding substrates, and in molding processes requiring precise positioning.

[0003] Patent document 1 discloses a molding method for decorative molded articles. The method involves pre-shaping a resin sheet after heating it, followed by vacuum molding of the resin sheet after reheating it. In other words, by performing shaping in two stages, deep drawing and shaping of small R-shapes can be achieved.

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 62-255119 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, the technology described in Patent Document 1 makes it difficult to achieve high-precision positioning during the molding of resin sheets. When the resin sheet softens due to heating, it is prone to sagging due to its own weight, making high-precision positioning difficult. Even when using the method described in Patent Document 1, which involves pre-shaping followed by reheating for further shaping, the resin sheet must still be sufficiently softened during heating to achieve high-precision positioning, making it impossible to avoid undulations or sagging of the resin sheet during heating. This results in misalignment or wrinkles due to variations in the state of the resin sheet in the molded product.

[0009] Therefore, the conventional method involves heating the resin sheet at a low temperature to prevent sagging, followed by molding with compressed air at ultra-high pressure, such as 3 MPa or higher. However, when molding transparent resin sheets using low-temperature heating and ultra-high pressure, residual stress can sometimes be generated inside the molded product, affecting the material's transparency. Furthermore, maintaining ultra-high pressure compressed air during molding results in problems such as expensive molding equipment and time-consuming molding processes.

[0010] Therefore, the object of the present invention is to provide a thermoforming apparatus that is less prone to misalignment or other defects when thermoforming resin sheets under relatively low pressure conditions.

[0011] [Technical means to solve the problem]

[0012] To achieve the aforementioned objective, one aspect of the thermoforming apparatus of the present invention has the following features.

[0013] (1) A thermoforming apparatus that heats a sheet material using a radiant heating unit and uses a mold to shape the sheet material or to coat and bond it to a substrate, characterized in that...

[0014] The radiant heating unit is composed of multiple heaters arranged together, and has a first region formed by the heaters corresponding to the protrusions of the mold, and a second region formed by the heaters excluding the first region.

[0015] The radiant heating unit is equipped with a heating control unit capable of different power controls in the first region and the second region.

[0016] With the aforementioned heating control unit, multi-stage heating control can be achieved by setting different heating conditions in the first and second heating stages, i.e.

[0017] As part of the first heating stage, the radiant heating unit performs initial heating of the sheet.

[0018] As part of the second heating stage, when the sheet is brought close to the mold and the sheet has abutted against the protrusion, the first region undergoes low-temperature heating with reduced power, and the second region undergoes high-temperature heating with increased power compared to the first region.

[0019] With the configuration described in (1) above, high-precision forming can be achieved even under relatively low-pressure conditions by using a thermoforming apparatus with multi-stage heating control, making it less prone to misalignment. This is because the following method is employed: in the first heating stage, the sheet is initially heated to a temperature that prevents sagging; after the sheet comes into contact with the protrusion of the mold, in the second heating stage, low-temperature heating with reduced power is performed in the first region, and high-temperature heating with increased power is performed in the second region compared to the first region.

[0020] During the first heating stage, the sheet heated by the radiant heating device experiences a temperature change at the contact point with the preheated mold. This is because the direct contact between the mold and the sheet causes temperature variations. Consequently, if the same heating continues, some areas will exceed the desired temperature while others will remain too low. To address this issue, heating can be performed in sections, allowing for further heating of desired areas while suppressing heating of unwanted areas, thus facilitating the shaping of the sheet into any desired form.

[0021] Specifically, the following forming process can be achieved: A first region is designated as a non-stretched area requiring alignment, for example. After first contacting the protrusion of the mold, the first region is heated at a low temperature, while a second region corresponding to the area to be deformed is heated at a higher power than the first region. By dividing the heating areas according to multi-stage heating control in this way, the portion to be deformed can be heated precisely, thus deforming the sheet. As a result, forming with higher shape accuracy can be achieved.

[0022] (2) In the thermoforming apparatus described in (1),

[0023] Preferably, the portion of the sheet material corresponding to the first region is designated as the portion on the molded article that requires alignment.

[0024] With the configuration described in (2) above, the portion of the sheet material corresponding to the first region first comes into contact with the protrusion of the mold and is heated at a low temperature in the second heating stage, so it is not easily affected by deformation during molding. Therefore, by setting the portion of the molded article that needs to be aligned, such as the printed portion or the portion used as a transparent window, as the portion of the sheet material corresponding to the first region, the effect of misalignment that occurs during molding can be minimized.

[0025] (3) In the thermoforming apparatus described in (1) or (2),

[0026] Preferably, the heating control unit includes a temperature confirmation unit for confirming the temperature of the sheet, and the multi-stage heating control is performed using the temperature data of the sheet measured by the temperature confirmation unit.

[0027] By using the form described in (3) above, the temperature of the sheet material being tested can be determined by using a radiation thermometer, thereby enabling more accurate control based on the heating control unit, thus achieving high shape accuracy molding.

[0028] (4) In the thermoforming apparatus described in (1)

[0029] Preferably, the sheet is held between the upper first chamber and the lower second chamber.

[0030] When forming the sheet, a pressure control unit is used to arbitrarily control the internal pressure of the first chamber or the second chamber to perform compressed air forming.

[0031] The configuration described in (4) above allows for compressed air forming of the sheet by supplying pressure to the first chamber or vacuum forming by depressurizing the second chamber. When performing compressed air forming or vacuum forming, the forming process is carried out by using multi-stage pressure control, which gradually increases the pressure from a low pressure, thus avoiding problems such as thinning of the wall thickness due to deformation exceeding the required degree.

[0032] (5) In the thermoforming apparatus described in (4)

[0033] Preferably, the pressure control unit has the function of controlling a first pressure control valve connected to the first chamber to switch the pressure in the first chamber to a first pressurized state and a second pressurized state with an internal pressure higher than the first pressurized state, or controlling a second pressure control valve connected to the second chamber to switch the pressure in the second chamber to a first vacuum state and a second vacuum state with a vacuum degree higher than the first vacuum state, thereby achieving the following multi-stage pressure control, namely,

[0034] As part of the first pressurization stage, after the sheet is brought close to the mold and has abutted against the protrusion, the pressure in the first chamber is controlled either to enter the first pressurization state or to enter the first vacuum state.

[0035] As a second pressurization stage, the pressure in the first chamber is controlled either by changing to the second pressurization state or by changing to the second vacuum state during the forming of the sheet.

[0036] With the configuration described in (5) above, the pressure in the first chamber or the second chamber can be changed in a multi-stage manner using a pressure control unit. Therefore, when switching to the second pressurization stage, compressed air forming or vacuum forming corresponding to the heating of the sheet can be performed, thereby suppressing the occurrence of problems such as sheet breakage or uneven thickness. Attached Figure Description

[0037] Figure 1 The diagram illustrates the general structure of the thermoforming apparatus according to this embodiment.

[0038] Figure 2 This is a plan view of the heater used in the thermoforming apparatus of this embodiment.

[0039] Figure 3 This is an explanatory diagram illustrating the third molding process of this embodiment.

[0040] Figure 4 This is an explanatory diagram illustrating the fourth molding process of this embodiment.

[0041] Figure 5 This is an explanatory diagram illustrating the fifth molding process of this embodiment.

[0042] Figure 6 This is a plan view of the heater in this embodiment, corresponding to the third step.

[0043] Figure 7 This is a plan view of the heater in this embodiment, corresponding to step 4.

[0044] Figure 8 This is a timeline showing the molding sequence of this embodiment.

[0045] Figure 9 This is a schematic diagram of the thermoforming apparatus system of this embodiment. Detailed Implementation

[0046] First, a general description of the structure of the thermoforming apparatus 100 according to an embodiment of the present invention will be given. Figure 1 This is an explanatory diagram illustrating the schematic structure of the thermoforming apparatus 100 according to this embodiment. The thermoforming apparatus 100 includes a first chamber 101, a second chamber 102, a heating unit 110, and a mold 200. The structure of the thermoforming apparatus 100 is as follows: a resin sheet S, which is to be molded, is held in the first chamber 101 and the second chamber 102, and molding is performed while being heated by the heating unit 110 disposed on the upper side.

[0047] The thermoforming apparatus 100 has a compressor and a vacuum pump (described later) connected to its first chamber 101 and second chamber 102, respectively. The pressure in the first chamber 101 and second chamber 102 can be adjusted by operating the compressor and vacuum pump. The first chamber 101 opens downwards, and the second chamber 102 opens upwards. The apparatus is designed to hold the resin sheet S by raising and lowering the first chamber 101 and second chamber 102.

[0048] A compressor or pressurizing tank (not shown) is connected to the first chamber 101, and a first valve V1 (described later) is installed along the first pipe P1, thereby pressurizing the interior of the first chamber 101 to any pressure. A vacuum pump (not shown) is connected to the second chamber 102, and a second valve V2 (described later) is installed along the second pipe P2, thereby depressurizing the interior of the second chamber 102 to any pressure. The first chamber 101 and the second chamber 102 are structures capable of withstanding the internal pressure generated during the pressurization and depressurization processes of the resin sheet S. The first valve V1 and the second valve V2 are pressure control valves that allow for arbitrary pressure control.

[0049] The resin sheet S is composed of thermoplastic polycarbonate and is cut into rectangular sheets with a thickness of approximately 300 μm. This material and thickness are merely an example, and the material and thickness of the resin sheet S are not limited thereto. However, the purpose of this invention is to solve problems in the processing of relatively thin resin sheets; therefore, the thickness of the resin sheet S used as the processed product is envisioned to be approximately 250 μm to 500 μm. Furthermore, it can also be used with thicker sheets; applying this invention to the molding of thicker sheets is expected to yield effective results.

[0050] Figure 2 A plan view of the heaters used in the thermoforming apparatus 100 is shown. The heating unit 110 is positioned above the resin sheet S and is a group of radiant heaters 111 used for the purpose of heating the resin sheet S from its upper surface. Figure 2 As shown, the heaters 111 are arranged in a tile-like pattern on the lower surface of the upper lifting device 120. Figure 2 The illustrations are arranged in 4 rows and 8 columns, but this does not preclude the addition or removal of rows and columns as needed. By adding rows and columns, more detailed shapes can be accommodated.

[0051] The heating unit 110 is held in the upper lifting device 120, which is a structure that allows the heating unit 110 to be moved to any height within the first chamber 101 by means of the first drive device 121 described later. Furthermore, each heater 111 is connected to the heating control unit 250 described later, allowing for arbitrary power adjustment.

[0052] A thermometer (S1, S2) is installed on the upper part of the upper lifting device 120. The thermometer (S1, S2) measures the temperature by aiming at the surface of the resin sheet S through the gap between the upper lifting device 120 and the heating unit 110. The first thermometer S1 and the second thermometer S2 are radiation thermometers that measure the temperature of the resin sheet S in a non-contact manner. Furthermore, for reasons described later, the number of thermometers is set as needed.

[0053] The mold 200 is held in a lower lifting device 210 that can be raised and lowered to any height by means of the second driving device 211 described later, for molding the resin sheet S. A protrusion 200a is formed on the mold 200. The protrusion 200a is a portion corresponding to, for example, a portion of the molded article M produced from the resin sheet S where misalignment is not allowed for printing patterns, or a portion where transparency is required and internal deformation is not allowed. For convenience, the portion of the mold 200 other than the protrusion 200a is defined as the lower portion 200b.

[0054] Furthermore, the protrusion 200a of the mold 200 corresponds to Figure 2 The first region A1 in the heating unit 110 shown. The first region A1 is Figure 2 The area enclosed by double-dotted lines and containing four heaters 111 is designated as the second area A2. The mold 200 consists of a protrusion 200a and a lower portion 200b other than the protrusion 200a. The second area A2 of the heating unit 110 corresponds to the lower portion 200b and the portion around the lower portion 200b that the resin sheet S abuts against. Furthermore, it is not impossible to increase the number of heating unit 110 areas to two or more.

[0055] Figure 9 A schematic diagram of the thermoforming apparatus system is shown. For ease of explanation, the heating unit 110 is omitted from the drawing, but the heaters 111 are connected to the heating control unit 250. Furthermore, a first thermometer S1 and a second thermometer S2 are connected to the heating control unit 250, and the control of the heaters 111 is triggered using data from the thermometers (S1 and S2). The first thermometer S1 is configured to target the portion of the sheet material corresponding to the first region A1, and the second thermometer S2 is configured to target the portion of the sheet material corresponding to the second region A2. Moreover, the number of thermometers can be increased as needed. If the heating unit 110 extends beyond the first region A1 and the second region A2, additional thermometers can be added and connected to the heating control unit 250 accordingly.

[0056] The first drive unit 121 driving the upper lifting device 120 and the second drive unit 211 driving the lower lifting device 210 are connected to the drive control unit 260. Although Figure 9The first chamber 101 and the second chamber 102 are not depicted, but the first valve V1 and the second valve V2 connected to the first chamber 101 and the second chamber 102 are connected to the pressure control unit 270. Furthermore, these heating control units 250, drive control units 260, and pressure control units 270 are equipped on the control console 300.

[0057] Next, the molding sequence of the resin sheet S will be explained. The molding process is as follows: Figure 1 , Figures 3 to 5 It was shown in the middle, according to Figure 1 , Figure 3 , Figure 4 , Figure 5 The molding process is carried out in sequence. Figure 8 This diagram illustrates the timeline for controlling various functions during the molding process. The horizontal axis shows the elapsed times t1 to t6, dividing the process into steps. Below, it is divided into steps 1 (Pr1) to 6 (Pr6) based on... Figure 8 To explain the operation of each device.

[0058] First, in the first process Pr1, with the image Figure 1 The first chamber 101 and the second chamber 102 are closed by using the first chamber 101 and the second chamber 102 to hold the placed resin sheet S, as shown.

[0059] Next, in the second process Pr2, the heating unit 110 is held in the position where the upper lifting device 120 has been lowered, and the resin sheet S is heated from above. Figure 1 (State of the process). The heating unit 110 performs initial heating using the heater 111. At this time, the heating is set to a slightly softened state for the resin sheet S, and continues until the set temperature is confirmed by the first thermometer S1 and the second thermometer S2. In this embodiment, the resin sheet S is polycarbonate, whose softening temperature is approximately 150 degrees Celsius. Therefore, at this point, it is heated in the first heating stage to a temperature of approximately 140 degrees Celsius, where polycarbonate begins to undergo heat deformation. Since it is desirable to quickly complete the heating of the resin sheet S, the ignition rate (power) of the heater 111 is set to 100%.

[0060] Next, in the third process Pr3, as Figure 3 As shown, the upper lifting device 120 is raised to lift the heating unit 110. Figure 8 (referred to as "heater"), while simultaneously using the lower lifting device 210 to raise the mold 200 so that it abuts against the resin sheet S ( Figure 8(Referring to the lifting platform). At this time, the protrusion 200a of the mold 200 abuts against the resin sheet S before the other parts of the mold 200 (the lower part 200b). Thus, while the resin sheet S is heated by the heating unit 110, the mold abuts against the hot resin sheet S, thereby deforming the resin sheet S. Here, since the mold 200 is heated to a low degree (around 120 degrees Celsius), the temperature drops locally when the protrusion 200a abuts against the resin sheet S.

[0061] At this time, the heating control unit 250 receives the image Figure 6 As shown, the first heating stage, in which all heaters 111 perform heating at the same power, is switched to a state similar to... Figure 7 As shown, heating is performed by changing the temperature settings in regions A1 and A2 in the form of a second heating stage. Here, Figure 7 The first region A1 shown is the position of the heating unit 110 corresponding to the protrusion 200a of the mold 200, and the second region A2 is the position other than the first region A1. The heater 111 corresponding to the first region A1 is set to an ignition rate of 10% when entering the third process Pr3, and the ignition rate of the remaining heaters 111 (including the one in the second region A2, which are arranged in the position surrounding the heater 111 corresponding to the first region A1) is set to 50%. Therefore, the portion of the resin sheet S that abuts against the lower part 200b is actively heated.

[0062] Next, in the fourth process, Pr4, the surface temperature of the resin sheet S reaches 170 degrees Celsius as a trigger (detected by the second thermometer S2). Pressurization begins in the first chamber 101, and depressurization begins in the second chamber 102 to initiate molding. In the fourth process, Pr4, within a specified time period from time t3 to time t4, the pressurization of the first chamber 101 is controlled by limiting the amount of compressed air supplied by the first valve V1. Figure 8 The pressure reduction in the second chamber 102 is controlled by limiting the amount of air discharged through the second valve V2 (referred to as "upper micro-compressed air"). Figure 8 This is referred to as "lower microvacuum" to achieve low-pressure molding. The opening of valves V1 and V2 is controlled by pressure control unit 270. Specifically, the pressure in chamber 101 is controlled to be 0.1 MPa, and the pressure in chamber 102 is controlled to be -0.05 MPa.

[0063] Next, in step 5, Pr5, as follows Figure 5 As shown, the supply of compressed air to the first chamber 101 is increased. Figure 8 (referred to as "upper compressed air") and increases the amount of air discharged from the second chamber 102 ( Figure 8This is referred to as "lower formal vacuum," meaning that valves 1 (V1) and 2 (V2) are opened to perform molding at a higher pressure than in the previous process. Here, as... Figure 8 As shown, the opening timing of the first valve V1 is controlled to be later than the opening timing of the second valve V2. Specifically, the pressure in the first chamber 101 is controlled to become 0.7 MPa, and the pressure in the second chamber 102 is controlled to become -0.1 MPa.

[0064] Finally, in step 6 (Pr6), the internal pressure of chamber 101 and chamber 102 is restored to atmospheric pressure. Afterward, chambers 101 and 102 are opened to remove the molded product M obtained by compressed air molding of the resin sheet S.

[0065] Since the thermoforming apparatus 100 of this embodiment has the above-described structure, it achieves the following functions and effects.

[0066] First, compressed air molding can achieve higher precision molded products M that are less prone to misalignment. This is a thermoforming apparatus 100 that heats a resin sheet S by means of a radiant heating device (heating unit 110) and molds the resin sheet S using a mold 200. The heating unit 110 is composed of a plurality of heaters 111 arranged together, and has a first region A1 formed by heaters 111 corresponding to the protrusions 200a of the mold 200 and a second region A2 formed by heaters 111 that do not have the first region A1. The heating unit 110 is equipped with a heating control unit that can control the power of the first region A1 and the second region A2 differently.

[0067] Furthermore, with the help of the heating control unit 250, the following multi-stage heating control can be achieved: as the first heating stage, the resin sheet S is heated at the same power in the first region A1 and the second region A2; as the second heating stage, when the mold 200 is brought close to the resin sheet S and the resin sheet S has abutted against the protrusion 200a, the first region A1 is heated at a first temperature with reduced power, and the second region A2 is heated at a second temperature higher than the first temperature, thereby achieving high-precision molding.

[0068] In other words, during the first heating stage, the resin sheet S is rapidly heated to a temperature that prevents sagging, and then the mold 200 contacts the resin sheet S, thereby preventing sagging of the resin sheet S. Furthermore, the heating area is divided into a first region A1 where heating is performed at a low temperature and a second region A2 where heating is performed at a higher temperature than in the first region A1. Thus, the portion of the resin sheet S to be deformed is heated as required in the second region A2, thereby achieving deformation. Therefore, multi-stage heating can be performed by controlling the heater 111 using the heating control unit 250, thereby preventing sagging of the resin sheet S and improving the molding accuracy of the molded product M.

[0069] At this time, the portion of the resin sheet S corresponding to the first region A1 is designated as the part requiring alignment. For example, if the surface of the resin sheet S is printed, misalignment would affect the performance of the product when it is molded into the molded article M, or the transparency would be affected by the deformation that occurs during molding. This prevents misalignment or internal deformation from causing the transparent portion to be difficult to transmit light. The portion of the resin sheet S corresponding to the first region A1 becomes the part that first abuts against the protrusion 200a of the mold 200 during molding. Furthermore, the power of the first region A1 is further reduced compared to the second region A2 during the second heating stage, thus preventing overheating that could deform the resin sheet S to the required degree, or in some cases, cause wrinkles or damage, and thus molding the resin sheet S into the target shape.

[0070] In addition, compressed air forming is like Figure 8 The molding process involved controlling the chamber pressure in multiple stages, as shown. The "Vacuum Pressure" graph at the bottom illustrates the following: Molding was performed with a low pressure (-0.05 MPa) in the second chamber 102 between time t3 and time t4. At this time, as described above, for the first chamber 101, the "Upper Micro Compressed Air" control was set to ON, and compressed air was supplied from the first pipe P1 via the pressure control unit 270 with throttling through the first valve V1, reducing the internal pressure to 0.1 MPa. For the second chamber 102, the "Lower Micro Vacuum" control was set to ON, and exhaust was performed from the second pipe P2 via the pressure control unit 270 with throttling through the second valve V2, reducing the internal pressure to -0.05 MPa. This is the first pressurization stage.

[0071] Next, between time t4 and time t5, the process transitions to a second pressurization stage where thermoforming is performed under even higher pressure (controlled at 0.7 MPa in chamber 101 and -0.1 MPa in chamber 102). This multi-stage pressurization allows for precise molding. Sudden application of high-pressure compressed air can easily cause the resin sheet S to become too thin or break; therefore, multi-stage pressurization ensures a uniform thickness of the molded product M.

[0072] By combining multi-stage heating and multi-stage pressurization in this way, and controlling the internal pressure of the chamber while thermoforming the resin sheet S, it is possible to prevent the resin sheet S from sagging during heating and to tightly press the resin sheet S onto the mold 200 during molding, thus achieving high shape accuracy. Furthermore, the previously used low-temperature heating and ultra-high-pressure molding methods are no longer required, thereby simplifying the device structure and potentially reducing costs.

[0073] The thermoforming apparatus 100 of the present invention has been described above, but the present invention is not limited thereto, and various modifications can be made without departing from its spirit. For example, the illustrated materials and temperatures can be modified as appropriate. Furthermore, if it is desired to further enhance the temperature gradient, the temperature gradient on the resin sheet S can be significantly enhanced by bringing the heating unit 110 closer to the resin sheet S during the second heating stage. Moving the heater 111 during the second heating stage is an effective method for molding complex shapes with many protrusions and depressions. Conversely, if the heating unit 110 is moved away from the resin sheet S, the temperature gradient can be made gentler.

[0074] Furthermore, as a multi-stage heating process, the initial heating of the resin sheet S in the first heating stage involves setting the ignition rate of heater 111 to 100%. However, this does not preclude the heating unit 110 from being divided into zones different from the first region A1 and the second region A2, or from being heated by changing the ignition rate based on the zones of the first region A1 and the second region A2. For example, consider the case where the ignition rate of the central portion of the resin sheet S is set lower than that of the surrounding area to uniformly heat the resin sheet S. The aim of this first heating stage is to achieve smooth heating of the resin sheet S and avoid problems such as sagging, which is different from the objective of minimizing the temperature rise of specific areas sought in the subsequent second heating stage. By performing such multi-stage heating with different heating conditions in the first and second heating stages, the present invention achieves high-precision molding of the resin sheet S.

[0075] Furthermore, this embodiment demonstrates an example of mold forming using mold 200, but it does not preclude the use of the present invention for thermoforming of a resin sheet S coated and bonded to a substrate. When the present invention is used for coating bonding, the adhesion of the resin sheet S to the substrate can be improved, and higher precision molding can be achieved. In addition, in this embodiment, the triggering of the first heating stage and the second heating stage uses data obtained from the first thermometer S1 and the second thermometer S2. However, besides using temperature data as the triggering method, time or observation of vacuum degree could also be considered as triggering methods, so modifications can be made as appropriate.

[0076] Furthermore, this embodiment illustrates the internal pressure of the first chamber 101 and the second chamber 102 of the thermoforming apparatus 100. Figure 8 The timing of these internal pressure changes is explained. The main purpose of the invention is to control the pressure in multiple stages, from low pressure in the first pressurization stage to higher pressure in the second pressurization stage. Therefore, it is not impossible to slightly increase or decrease these timing values ​​according to the thickness and temperature of the resin sheet S.

[0077] Symbol Explanation

[0078] S…Resin Sheets

[0079] A1…Area 1

[0080] A2…Area 2

[0081] 100…Thermoforming apparatus

[0082] 110… Heating Unit

[0083] 111… heater

[0084] 250… Heating Control Unit

[0085] 200… mold

[0086] 200a...Protrusion.

Claims

1. A thermoforming apparatus which performs heating of a sheet by means of a radiant heating unit, and performs mold shaping of the sheet or adhesive bonding of a coating to a base material using a mold, characterized by, the radiant heating unit is arranged with a plurality of heaters, and has a first region constituted by the heaters corresponding to a convex portion of the mold, and a second region constituted by the heaters excluding the first region, the radiant heating unit is provided with a heating control unit capable of performing different power control in the first region and the second region, by means of the heating control unit, multi-stage heating control in which different heating conditions are set in a first heating stage and a second heating stage is enabled, i.e., as the first heating stage, initial heating of the sheet by the radiant heating unit is performed, as the second heating stage, when the sheet is brought into close proximity with the mold so that the sheet abuts against the convex portion, low-temperature heating with reduced power is performed in the first region, and high-temperature heating with increased power compared to the first region is performed in the second region.

2. The thermoforming apparatus according to claim 1, characterized by, a portion of the sheet corresponding to the first region is set to be a portion aligned with a desired position on a molded product.

3. The thermoforming apparatus according to claim 1 or 2, characterized by, the heating control unit is provided with a temperature confirmation unit for confirming the temperature of the sheet, and the multi-stage heating control is performed using temperature data of the sheet measured by the temperature confirmation unit.

4. The thermoforming apparatus according to claim 1, characterized by, the sheet is held between a first chamber disposed in an upper portion and a second chamber disposed in a lower portion, when the sheet is molded, compressed air molding is performed using a pressure control unit to arbitrarily control the internal pressure of the first chamber or the second chamber.

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