JP2022114639A - Thermoforming apparatus and thermoforming method - Google Patents

Abstract

To provide a thermoforming apparatus and a thermoforming method that can stably thermoform a sheet.SOLUTION: A thermoforming apparatus 1 for thermoforming a sheet SH according to one aspect of the present disclosure includes: a heat plate 12 disposed in an upper chamber 16 on the upper side of the thermoplastic sheet SH to heat the sheet SH; a mold 13 arranged in a lower chamber 17 provided below the sheet SH to mold the sheet SH; a control unit 15 for various control; an upper vacuum pressure sensor 21 that measures a vacuum pressure in the upper chamber 16; and a lower vacuum pressure sensor 31 that measures a vacuum pressure in the lower chamber 17. The control unit 15 starts driving the heat plate 12 or/and the mold 13 when the vacuum pressure in the upper chamber 16 or/and the vacuum pressure in the lower chamber 17 reaches a set pressure value based on a measurement of the upper vacuum pressure sensor 21 and a measurement of the lower vacuum pressure sensor 31.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to thermoforming apparatus and thermoforming methods.

Patent Literature 1 discloses a technique for forming a laminated molded body by vacuum-bonding a skin material to the surface of a core material.

Japanese Patent Application Laid-Open No. 2002-18940

When the sheet is thermoformed, if the pressure (vacuum pressure) in the chamber in which the sheet is placed is not stable, the behavior of the sheet to be formed cannot be controlled, and the sheet may not be thermoformed stably. . Patent Document 1 discloses a technique for forming a laminated molded body by vacuum-bonding a skin material to the surface of a core material, but does not disclose the behavior control of the core material and the skin material to be molded. No method for stably thermoforming the sheet is disclosed.

Accordingly, the present disclosure has been made to solve the above-described problems, and an object thereof is to provide a thermoforming apparatus and a thermoforming method capable of stably thermoforming a sheet.

One aspect of the present disclosure, which has been made to solve the above problems, includes a hot plate disposed in an upper chamber provided on the upper side of a thermoplastic sheet to heat the sheet, and a lower side provided on the lower side of the sheet. An upper vacuum for measuring the vacuum pressure in the upper chamber in a thermoforming apparatus for thermoforming the sheet, which is arranged in a chamber and has a mold for forming the sheet and a control unit for performing various controls. a pressure sensor, and a lower vacuum pressure sensor that measures the vacuum pressure in the lower chamber, and the control unit, based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor, The driving of the hot plate and/or the mold is started when the vacuum pressure in the upper chamber or/and the vacuum pressure in the lower chamber reaches a set pressure value.

According to this aspect, the vacuum pressure in the upper chamber and/or the vacuum pressure in the lower chamber is used as a trigger to start driving the hot plate and the mold. Therefore, while the environment in the upper chamber and/or the lower chamber is stabilized and the behavior of the sheet is controlled, the sheet can be heated by the hot plate and the sheet can be formed by the mold. Therefore, the sheet can be thermoformed stably.

In the above aspect, the control unit sets the vacuum pressure in the upper chamber to the set pressure value to bring the hot plate into contact with the sheet to heat the sheet, and then sucks the inside of the lower chamber, When the vacuum pressure in the lower chamber reaches the set pressure value, the hot plate starts to rise to separate the hot plate from the sheet, and the mold starts to rise to move the mold. is brought into contact with the sheet and the sheet is molded with the mold.

According to this aspect, after the sheet is heated, when the heated sheet is formed by the mold, the vacuum pressure in the lower chamber is used as a trigger to start raising the hot plate and the mold. Therefore, the environment in the lower chamber is stabilized, and the sheet can be molded by the molding die while controlling the behavior of the sheet. Therefore, the sheet can be thermoformed stably.

In the above aspect, the control unit raises the hot plate and the mold while maintaining the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber at the same pressure or substantially the same pressure. is preferred.

According to this aspect, the sheet can be formed by the forming die while keeping the sheet horizontal.

In the above aspect, it is preferable that the control unit supplies compressed air into the upper chamber to pressurize the inside of the upper chamber when the sheet is formed by the mold.

According to this aspect, when the sheet is formed by the forming die, the sheet can be brought into contact with the forming die more reliably by pressurizing the inside of the upper chamber, so that the sheet is formed by the forming die more stably. It can be performed.

In the above aspect, a first vacuum pump that sucks the inside of the upper chamber, an upper opening/closing valve that opens and closes a flow path connected to the upper chamber, a second vacuum pump that sucks the inside of the lower chamber, and the lower chamber. and a lower opening/closing valve that opens and closes a flow path leading to the upper opening/closing valve and the lower opening/closing valve based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor. Preferably, valves are opened and closed to maintain the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber at the set pressure values.

According to this aspect, since the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber can be stably maintained at the set pressure values, the behavior of the sheet can be controlled more accurately.

Another aspect of the present disclosure, which has been made to solve the above problems, is a heat plate disposed in an upper chamber provided above a thermoplastic sheet to heat the sheet, and a heat plate provided below the sheet. In a thermoforming method for thermoforming the sheet using a mold arranged in a lower chamber for molding the sheet, an upper vacuum pressure sensor for measuring a vacuum pressure in the upper chamber; and the lower chamber. and a lower vacuum pressure sensor that measures the vacuum pressure in the upper chamber and/or the lower vacuum pressure sensor based on the measurement value of the upper vacuum pressure sensor and the measurement value of the lower vacuum pressure sensor. The driving of the hot plate and/or the mold is started when the vacuum pressure in the chamber reaches a set pressure value.

According to the thermoforming apparatus and thermoforming method of the present disclosure, a sheet can be thermoformed stably.

It is a figure which shows the schematic structure of the thermoforming apparatus of this embodiment, and is a figure which shows a heating process. It is a figure which shows schematic structure of the thermoforming apparatus of this embodiment, and is a figure which shows a vacuum process. It is a figure which shows the schematic structure of the thermoforming apparatus of this embodiment, and is a figure which shows a shaping|molding process. FIG. 4 is a diagram showing a time chart showing timings of driving an upper vacuum valve, a lower vacuum valve, a hot plate, and a mold according to the present embodiment; 5 is a diagram showing how the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber change when the upper vacuum valve, the lower vacuum valve, the hot plate, and the mold are driven at the timing shown in FIG. 4; FIG. It is a diagram showing a time chart showing the timing of driving the upper vacuum valve, the lower vacuum valve, the hot plate and the mold in the conventional technology. 7 is a diagram showing how the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber change when the upper vacuum valve, the lower vacuum valve, the hot plate, and the mold are driven at the timing shown in FIG. 6; FIG.

A thermoforming apparatus 1 that implements one embodiment of the thermoforming apparatus and thermoforming method of the present disclosure will be described.

<Outline description of the entire thermoforming apparatus>
First, an overview of the entire thermoforming apparatus 1 will be described.

The thermoforming apparatus 1 is an apparatus for thermoforming a sheet SH, and as shown in FIGS. have.

A seat SH is arranged inside the housing 11, an upper chamber 16 is provided above the seat SH, and a lower chamber 17 is provided below the seat SH.

The sheet SH is, for example, a general thermoplastic resin sheet such as polyvinyl chloride (PVC). Note that the JIS (Japanese Industrial Standards) packaging terminology standard defines a thin plate-like plastic material having a thickness of 250 μm or more as a sheet, and a film-like plastic material having a thickness of less than 250 μm as a film. However, in the present embodiment, the thickness of the plastic material to be thermoformed by the thermoforming apparatus 1 is not distinguished, and the plastic material having a thickness within the category of film is generically referred to as the sheet SH.

The hot plate 12 is a plate that is arranged in the upper chamber 16, contacts the sheet SH, and heats the sheet SH.

The mold 13 is arranged in the lower chamber 17, is provided at a position opposite to the hot plate 12 with respect to the sheet SH, and is a mold for molding the sheet SH by coming into contact with the sheet SH. .

The table 14 is a stand on which the mold 13 is arranged on its upper surface, and the mold 13 is moved up and down.

The control unit 15 is a device that performs various controls for each device in the thermoforming apparatus 1 . Control for molding SH, etc. are performed. The control unit 15 can also receive measured values from an upper vacuum pressure sensor 21 and a lower vacuum pressure sensor 31, which will be described later.

In this embodiment, the thermoforming apparatus 1 includes an upper vacuum pressure sensor 21, a first vacuum pump 22, an upper vacuum valve 23, a lower vacuum pressure sensor 31, a second vacuum pump 32, and a lower vacuum valve 33. , a double-extraction vacuum valve 41 , a compressed air supply section 51 , and a compressed air valve 52 .

The upper vacuum pressure sensor 21 is a sensor that measures the vacuum pressure inside the upper chamber 16 . The first vacuum pump 22 is a pump that sucks the inside of the upper chamber 16 . The upper vacuum valve 23 is a valve provided in a channel 24 that connects the inside of the upper chamber 16 and the first vacuum pump 22 , and opens and closes the channel 24 . It should be noted that the upper vacuum valve 23 is an example of the "upper on-off valve" of the present disclosure.

The lower vacuum pressure sensor 31 is a sensor that measures the vacuum pressure inside the lower chamber 17 . The second vacuum pump 32 is a pump that sucks the inside of the lower chamber 17 (or the inside of the upper chamber 16). The lower vacuum valve 33 is a valve provided in a channel 34 that connects the inside of the lower chamber 17 and the second vacuum pump 32 , and opens and closes the channel 34 . Note that the lower vacuum valve 33 is an example of the "lower on-off valve" of the present disclosure.

The double-suction vacuum valve 41 connects to a position in the flow path 24 closer to the first vacuum pump 22 than the upper vacuum valve 23 and a position in the flow path 34 closer to the second vacuum pump 32 than the lower vacuum valve 33. 42 is a valve that opens and closes the channel 42 .

The compressed air supply unit 51 is a device that supplies compressed air to the upper chamber 16 . The compressed air valve 52 is a valve provided in a flow path 53 that connects the inside of the upper chamber 16 and the compressed air supply section 51 , and opens and closes the flow path 53 .

In the thermoforming apparatus 1 having such a configuration, first, as shown in FIG. 1, as a heating step, the control unit 15 evacuates the inside of the upper chamber 16 to bring the hot plate 12 into contact with the sheet SH. The sheet SH is heated. Next, as shown in FIG. 2, as a vacuum process, the controller 15 evacuates the inside of the upper chamber 16 and the inside of the lower chamber 17 to a vacuum state. Then, the control unit 15 raises the hot plate 12 to separate it from the sheet SH, and raises the table 14 to bring the die 13 into contact with the sheet SH. Next, as shown in FIG. 3 , in the molding process, the control unit 15 pressurizes the inside of the upper chamber 16 with the mold 13 to mold the sheet SH.

<Vacuum pressure in the chamber and drive timing of each device>
Here, in the prior art, when shifting from the vacuum process to the molding process, as shown in FIG. 6, the upper vacuum valve 23 and the lower vacuum valve 33 are opened to open the first vacuum pump 22 and the second vacuum. The inside of the upper chamber 16 and the inside of the lower chamber 17 were sucked by the pump 32 . Then, at the timing (time t in FIG. 7) at which the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 are assumed to be the same, the hot plate 12 and the mold 13 are placed in the raised position. As shown, the hot plate 12 and the mold 13 started to rise.

However, if the timing of placing the hot plate 12 and the mold 13 in the raised position is too early (time t-α in FIG. 7), as shown in FIG. Specifically, the vacuum pressure (degree of vacuum) in the upper chamber 16 becomes lower (higher) than the vacuum pressure (degree of vacuum) in the lower chamber 17, and heat is generated. When the plate 12 and the mold 13 are arranged at the raised position, the sheet SH may bulge upward. As a result, the mold 13 may not stably form the sheet SH.

Alternatively, when the timing of placing the hot plate 12 and the mold 13 in the raised position is too late (time t+α in FIG. 7), as shown in FIG. Specifically, the vacuum pressure (degree of vacuum) in the upper chamber 16 becomes higher (lower) than the vacuum pressure (degree of vacuum) in the lower chamber 17, and the hot plate 12 When the mold 13 is arranged at the raised position, the sheet SH may hang down. As a result, the mold 13 may not stably form the sheet SH.

Therefore, in this embodiment, when the vacuum pressure in the lower chamber 17 reaches the set pressure value based on the measurement value of the lower vacuum pressure sensor 31 in the vacuum process, the control unit 15 raises the hot plate 12 and the mold 13. and control to shift to the molding process.

Hereinafter, in the thermoforming apparatus 1 of this embodiment, the timing of driving each device of the upper vacuum valve 23, the lower vacuum valve 33, the hot plate 12, and the mold 13, the vacuum pressure in the upper chamber 16, and the inside of the lower chamber 17 A detailed description will be given of how the vacuum pressure of .

First, in the heating process, as shown in FIG. 4, at time t1, the control unit 15 places the hot plate 12 and the mold 13 in the lowered position (see FIG. 1), and the upper vacuum valve 23 is opened. , the suction inside the chamber 16 by the first vacuum pump 22 is started. Further, the control unit 15 opens the double-suction vacuum valve 41 and starts the suction inside the chamber 16 by the second vacuum pump 32 . As a result, as shown in FIG. 5, the vacuum pressure in the upper chamber 16 is lowered (that is, the degree of vacuum is increased).

After that, at time t2, based on the measurement value of the upper vacuum pressure sensor 21, the control unit 15 determines that the vacuum pressure in the upper chamber 16 is the set pressure value (more specifically, between the upper limit and the lower limit of the set pressure value). ), the upper vacuum valve 23 is closed to maintain the vacuum pressure in the upper chamber 16 at the set pressure value, as shown in FIG. At this time, the control unit 15 also closes the double vacuum valve 41 . Then, the control unit 15 heats the sheet SH with the hot plate 12 while maintaining the vacuum pressure in the upper chamber 16 at the set pressure value. The lower vacuum valve 33 is closed during the heating process.

Next, in the vacuum process, at time t3, the controller 15 opens the lower vacuum valve 33 while keeping the hot plate 12 and the mold 13 in the lowered position (see FIG. 2). 2 Start sucking the inside of the lower chamber 17 by the vacuum pump 32 . This reduces the vacuum pressure in the lower chamber 17 as shown in FIG. In the vacuum process, the controller 15 opens and closes the upper vacuum valve 23 based on the measurement value of the upper vacuum pressure sensor 21 to maintain the vacuum pressure in the upper chamber 16 at the set pressure value.

Next, at time t4, based on the measurement value of the lower vacuum pressure sensor 31, the control unit 15 determines that the vacuum pressure in the lower chamber 17 is the set pressure value (more specifically, the value between the upper limit and the lower limit of the set pressure value). value), the heating plate 12 and the mold 13 start to rise. Then, at time t5, the hot plate 12 and the mold 13 are placed at the raised position (the position shown in FIG. 3).

Here, from time t4 to time t5, the control unit 15 keeps the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 at the same pressure or substantially the same pressure. The mold 13 is raised. As a result, when the hot plate 12 and the mold 13 are raised to bring the mold 13 into contact with the sheet SH, the sheet SH can be kept horizontal. can be suppressed.

In addition, since the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 are maintained at the same pressure or substantially the same pressure, the vacuum process can quickly shift to the forming process, so that the sheet SH is separated from the hot plate 12. The time until the mold 13 contacts can be shortened. Therefore, when shifting from the vacuum process to the forming process, it is possible to prevent deterioration of formability of the sheet SH by suppressing a decrease in the temperature of the sheet SH.

In the example shown in FIG. 5, the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 are kept substantially the same. Specifically, the vacuum pressure (degree of vacuum) in the upper chamber 16 is slightly lower (higher) than the vacuum pressure (degree of vacuum) in the lower chamber 17 so that the sheet SH is horizontal without sagging due to its own weight. ).

After that, as shown in FIG. 4, the control unit 15, with the hot plate 12 and the mold 13 placed in the raised position, based on the measurement values of the upper vacuum pressure sensor 21 and the lower vacuum pressure sensor 31, By opening and closing the upper vacuum valve 23 and the lower vacuum valve 33 respectively, the vacuum pressures in the upper chamber 16 and the lower chamber 17 are maintained at set pressure values, as shown in FIG.

Then, in the molding process, at time t6, the control unit 15 opens the compressed air valve 52 and supplies compressed air from the compressed air supply unit 51 through the flow path 53 into the upper chamber 16 to pressurize it. , the vacuum pressure in the upper chamber 16 is increased (that is, the degree of vacuum is lowered) to create a compressed air state, and the sheet SH is molded by the mold 13 .

In this way, in this embodiment, the controller 15 controls the vacuum pressure in the lower chamber 17 to reach the set pressure value based on the measurement value of the lower vacuum pressure sensor 31 when the vacuum process is shifted to the molding process. When it reaches, the driving of the hot plate 12 and the driving of the mold 13 are started. Specifically, when the vacuum pressure in the lower chamber 17 reaches the set pressure value, the controller 15 starts to raise the hot plate 12 to separate the hot plate 12 from the sheet SH, and raises the mold 13. is started to bring the mold 13 into contact with the sheet SH, and the mold 13 forms the sheet SH.

<Action and effect of the present embodiment>
As described above, according to the present embodiment, the controller 15 controls the vacuum pressure in the lower chamber 17 to be the set pressure based on the measurement value of the lower vacuum pressure sensor 31 when shifting from the vacuum process to the molding process. When the value is reached, the hot plate 12 and mold 13 are started to rise (drive).

In this manner, the hot plate 12 and the mold 13 are started to rise using the vacuum pressure in the lower chamber 17 as a trigger. Therefore, the environment (that is, the pressure) in the lower chamber 17 is stabilized, and the sheet SH can be molded by the mold 13 while controlling the behavior of the sheet SH. Therefore, the sheet SH can be thermoformed stably.

More specifically, the controller 15 heats the sheet SH by bringing the hot plate 12 into contact with the sheet SH as a heating process, and then sucks the inside of the lower chamber 17 as a vacuum process. After that, when the vacuum pressure in the lower chamber 17 reaches the set pressure value, the control unit 15 starts to raise the hot plate 12 to separate the hot plate 12 from the sheet SH, and the mold 13 is opened. It starts to rise and comes into contact with the sheet SH, and the sheet SH is molded by the mold 13 as a molding step.

In this way, after the heating process of heating the sheet SH, when performing the molding process of molding the heated sheet SH with the mold 13, the vacuum pressure in the lower chamber 17 triggers the hot plate 12 and the metallic mold. Start the mold 13 to rise. Therefore, the environment in the lower chamber 17 is stabilized, and the sheet SH can be molded by the mold 13 while controlling the behavior of the sheet SH. Therefore, the sheet SH can be thermoformed stably.

Further, the control unit 15 raises the hot plate 12 and the mold 13 while maintaining the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 at the same pressure or substantially the same pressure.

As a result, the sheet SH can be stably formed by the mold 13 by moving from the vacuum process to the forming process while keeping the sheet SH horizontal.

Further, in the molding process, the control unit 15 supplies compressed air into the upper chamber 16 to pressurize the inside of the upper chamber 16 when the mold 13 is brought into contact with the sheet SH to mold the sheet SH.

In this way, when the sheet SH is molded by the mold 13, by pressurizing the inside of the upper chamber 16, the sheet SH can be brought into contact with the mold 13 more reliably, so that the mold can be formed more stably. 13 can be used to form the sheet SH.

Based on the measured value of the upper vacuum pressure sensor 21 and the measured value of the lower vacuum pressure sensor 31, the control unit 15 opens and closes the upper vacuum valve 23 and the lower vacuum valve 33, respectively, while adjusting the vacuum pressure in the upper chamber 16. , the vacuum pressure in the lower chamber 17 is maintained at the set pressure value.

As a result, the vacuum pressure in the upper chamber 16 and the vacuum pressure in the lower chamber 17 can be stably maintained at the set pressure values, so that the behavior of the sheet SH can be controlled more accurately.

For example, the set pressure value in the upper chamber 16 is set lower than the set pressure value in the lower chamber 17, and the degree of vacuum in the upper chamber 16 is made higher than the degree of vacuum in the lower chamber 17. Each vacuum pressure in the inner and lower chambers 17 may be maintained. As a result, the hot plate 12 and the mold 13 are raised in a state in which the sheet SH is blown upward (that is, deformed), the mold 13 is brought into contact with the sheet SH, and the sheet SH is formed by the mold 13. can do. As a result, the contact state between the mold 13 and the sheet SH can be changed depending on the part of the sheet SH, so that the thickness balance of each part of the sheet SH can be controlled.

Alternatively, by changing the balance between the set pressure value in the upper chamber 16 and the set pressure value in the lower chamber 17 to change the balance between the degree of vacuum in the upper chamber 16 and the degree of vacuum in the lower chamber 17, the chamber 16 Each vacuum pressure in the inner and lower chambers 17 may be maintained. This makes it possible to change the presence, position, and size of wrinkles on the sheet SH.

It should be noted that the above-described embodiment is merely an example and does not limit the present disclosure in any way, and of course various improvements and modifications are possible without departing from the gist of the present disclosure.

For example, in the heating process, the controller 15 starts lowering the hot plate 12 when the vacuum pressure in the upper chamber 16 reaches a set pressure value based on the measurement value of the upper vacuum pressure sensor 21. , the hot plate 12 may be brought into contact with the sheet SH.

1 thermoforming apparatus 11 housing 12 hot plate 13 mold 14 table 15 control unit 16 upper chamber 17 lower chamber 21 upper vacuum pressure sensor 22 first vacuum pump 23 upper vacuum valve 24 channel 31 lower vacuum pressure sensor 32 second vacuum Pump 33 Lower vacuum valve 34 Channel 41 Double vacuum valve 42 Channel 51 Compressed air supply part 52 Compressed air valve 53 Channel SH Seat

One aspect of the present disclosure, which has been made to solve the above problems, includes a hot plate disposed in an upper chamber provided on the upper side of a thermoplastic sheet to heat the sheet, and a lower side provided on the lower side of the sheet. An upper vacuum for measuring the vacuum pressure in the upper chamber in a thermoforming apparatus for thermoforming the sheet, which is arranged in a chamber and has a mold for forming the sheet and a control unit for performing various controls. a pressure sensor, and a lower vacuum pressure sensor that measures the vacuum pressure in the lower chamber, and the control unit, based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor, When the vacuum pressure in the upper chamber or/and the vacuum pressure in the lower chamber reaches a set pressure value, the driving of the hot plate and/or the mold is started , After the sheet is heated by bringing the hot plate into contact with the sheet by setting the vacuum pressure in the chamber to the set pressure value, the inside of the lower chamber is sucked, and the vacuum pressure in the lower chamber reaches the set pressure value. When the hot plate is reached, the hot plate starts to rise to separate the hot plate from the sheet, and the mold starts to rise to bring the mold into contact with the sheet, and the mold causes the sheet to move. characterized by molding

According to this aspect, the vacuum pressure in the upper chamber and/or the vacuum pressure in the lower chamber is used as a trigger to start driving the hot plate and the mold. Therefore, while the environment in the upper chamber and/or the lower chamber is stabilized and the behavior of the sheet is controlled, the sheet can be heated by the hot plate and the sheet can be formed by the mold. Therefore, the sheet can be thermoformed stably.
After the sheet is heated, when the heated sheet is formed by the forming die, the vacuum pressure in the lower chamber is used as a trigger to start raising the hot plate and the forming die. Therefore, the environment in the lower chamber is stabilized, and the sheet can be formed by the mold while controlling the behavior of the sheet. Therefore, the sheet can be thermoformed stably.

Another aspect of the present disclosure, which has been made to solve the above problems, is a heat plate disposed in an upper chamber provided above a thermoplastic sheet to heat the sheet, and a heat plate provided below the sheet. In a thermoforming method for thermoforming the sheet by using a mold arranged in a lower chamber for molding the sheet, an upper vacuum pressure sensor for measuring a vacuum pressure in the upper chamber; and the lower chamber. and a lower vacuum pressure sensor that measures the vacuum pressure in the upper chamber and/or the lower vacuum pressure sensor based on the measurement value of the upper vacuum pressure sensor and the measurement value of the lower vacuum pressure sensor. When the vacuum pressure in the chamber reaches a set pressure value, the driving of the hot plate and/or the mold is started , and the vacuum pressure in the upper chamber is set to the set pressure value. After the sheet is heated by bringing the hot plate into contact with the sheet, the inside of the lower chamber is sucked, and when the vacuum pressure in the lower chamber reaches the set pressure value, the hot plate starts to rise. Then, the hot plate is separated from the sheet, and the forming die starts to rise to bring the forming die into contact with the sheet, and the sheet is formed by the forming die .

Claims (6)

a hot plate disposed in an upper chamber provided above a thermoplastic sheet to heat the sheet;
a mold disposed in a lower chamber provided below the sheet for molding the sheet;
and a control unit that performs various controls,
In a thermoforming device for thermoforming the sheet,
an upper vacuum pressure sensor that measures the vacuum pressure in the upper chamber;
a lower vacuum pressure sensor that measures the vacuum pressure in the lower chamber;
Based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor, the control unit determines whether the vacuum pressure in the upper chamber and/or the vacuum pressure in the lower chamber has reached a set pressure value. sometimes initiating the hot plate drive and/or the mold drive;
A thermoforming apparatus characterized by: The thermoforming apparatus of claim 1, wherein
The control unit
After setting the vacuum pressure in the upper chamber to the set pressure value and bringing the hot plate into contact with the sheet to heat the sheet,
The inside of the lower chamber is sucked, and when the vacuum pressure in the lower chamber reaches the set pressure value, the hot plate starts to rise to separate the hot plate from the sheet, and the mold is opened. starting to rise to bring the mold into contact with the sheet;
shaping the sheet with the mold;
A thermoforming apparatus characterized by: The thermoforming apparatus of claim 2, wherein
The control unit raises the hot plate and the mold while maintaining the vacuum pressure in the upper chamber and the vacuum pressure in the lower chamber at the same pressure or substantially the same pressure;
A thermoforming apparatus characterized by: The thermoforming apparatus of claim 2 or 3,
The control unit supplies compressed air into the upper chamber to pressurize the inside of the upper chamber when the sheet is molded by the mold;
A thermoforming apparatus characterized by: In the thermoforming apparatus according to any one of claims 1 to 4,
a first vacuum pump that sucks the inside of the upper chamber and an upper opening/closing valve that opens and closes a flow path connected to the upper chamber;
a second vacuum pump that sucks the inside of the lower chamber and a lower opening/closing valve that opens and closes a flow path connected to the lower chamber;
The control unit opens and closes the upper on-off valve and the lower on-off valve based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor to control the vacuum pressure in the upper chamber and the lower vacuum pressure. maintaining the vacuum pressure in the chamber at the set pressure value;
A thermoforming apparatus characterized by: a hot plate disposed in an upper chamber provided above a thermoplastic sheet to heat the sheet;
a mold that is disposed in a lower chamber provided below the sheet and molds the sheet,
In the thermoforming method for thermoforming the sheet,
an upper vacuum pressure sensor that measures the vacuum pressure in the upper chamber;
using a lower vacuum pressure sensor that measures the vacuum pressure in the lower chamber,
Based on the measured value of the upper vacuum pressure sensor and the measured value of the lower vacuum pressure sensor, when the vacuum pressure in the upper chamber and/or the vacuum pressure in the lower chamber reaches a set pressure value, the heat is generated. starting the drive of the plate and/or the drive of the mold;
A thermoforming method characterized by:

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