JPH03130126A - Method for forming thermoplastic sheet - Google Patents

Abstract

PURPOSE:To make it possible to obtain favorable formability regardless of the structure and material of sheet by a method wherein regular forming is performed to thermoplastic sheet, which has been preformed in each cavity, with each plug under the condition that suction under vacuum is applied from the cavity side of a forming drum. CONSTITUTION:Under the condition that thermoplastic sheet 11 is brought into close contact with a forming drum 31 having cavities 34, at the peripheral edge part of each of which heat insulating material layers 36 are produced, the thermoplastic sheet 11 is preformed in the cavity 34 by being externally heated and sucked under vacuum from the cavity 34 side of the forming drum 31. Next, regular forming is performed to the thermoplastic sheet 11, which has been preformed in the cavity 34, with each plug 39 under the condition that suction under vacuum is applied from the cavity 34 side of the forming drum 31. At this time, if the suction under vacuum from the cavity 34 side, which is similarly applied at preforming, is not applied, poor releasability of a formed item from the plug 39 results and no favorable forming state is obtained. Thus, pockets can be favorably heat-formed regardless of the material and structure of the thermoplastic sheet 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for forming a thermoplastic sheet, and can be used, for example, in blister packaging used for packaging foods, daily necessities, medicines, etc. can.

[Background technology] In recent years, so-called blister packaging has come into use, in which a pocket is formed in a resin sheet to match the shape of the product to be packaged, contents such as pharmaceuticals are placed inside the pocket, and the pocket is then sealed with a backing paper. It's coming.

Conventionally, polyvinyl chloride (PVC) has been exclusively used as the material for this resin sheet, but polyvinyl chloride
This involves problems such as the generation of harmful gases during incineration. Therefore, instead of polyvinyl chloride, polypropylene (P
P) came to be used, and in order to further improve moisture resistance, polypropylene was combined with polyvinylidene chloride (PVDC), polychlorotrifluoroethylene (P), etc.
The use of composite materials such as CTFE) has also been proposed.

[Problems to be Solved by the Invention] The present applicant has found that even if the material of the resin sheet is polypropylene, the moldability, molding speed, sealing property, curling property, and half-cut property of the conventional molding for polyvinyl chloride He proposed a device that would provide better characteristics than those obtained by the device (Japanese Patent Application No. 63-231578). However, if the resin sheet is not a single layer but has a laminated structure made of multiple materials, each material has a different melting point and softening temperature, so thermoforming must be performed at a low temperature, The high-temperature vacuum forming apparatus and method for layered sheets did not provide satisfactory properties in terms of formability and the like.

Conventionally, there is a hot plate heating/plug assist pressure forming machine as a molding machine that can also mold laminated resin sheets.
According to this, PVC single layer sheet and PVC/PVD
Although it is possible to form a laminated sheet of C, the high-speed formability and the formability of PP are poor. In addition, hot plate heating
According to the pressure forming apparatus, in addition to these problems, if the thickness of the resin sheet is thin, good moldability cannot be obtained.

In addition, indirect heating/drum vacuum forming equipment (1986-7)
131, JP 56-39266, JP 58-12
6117, Japanese Unexamined Patent Publication No. 58-126118, Patent Application No. 63
-231578'), it is possible to form PP single-layer sheets and PVC/PVDC laminated sheets;
PP/PCTFE/PP and PVC/PCTFE/PP
It is difficult to form laminated sheets such as

An object of the present invention is to provide a method for molding a thermoplastic sheet that provides good moldability regardless of the structure and material of the sheet.

[Means and effects for solving the problems] A thermoplastic sheet molding method according to the present invention is a thermoplastic sheet molding method in which a thermoplastic sheet is supplied to a molding drum to thermoform pockets. a step in which the thermoplastic sheet is brought into close contact with a molding drum having a cavity with a heat insulating layer formed on the periphery, and the thermoplastic sheet is preformed into the cavity by vacuum suction from the cavity side of the molding drum while being heated externally; The thermoplastic sheet preformed in the cavity is subjected to main molding using a plug while vacuum suction is applied from the cavity side of the molding drum.

In the main molding as well, if vacuum suction is not performed from the cavity side as in the preforming, not only will the releasability of the molded product from the plug be poor, but also a good molded state will not be obtained.

If a heat insulating layer is not formed around the periphery of the molded tram cavity, the PTPI'ffl part will curl back.

As the material for this heat insulating layer, for example, polyimide or the like can be used.

During main molding in this molding method, a molding drum may be driven to rotate continuously, and a rotary plug may be pushed into a cavity of the molding drum to perform main molding of the thermoplastic sheet.

In addition, during this main forming, the forming drum is driven to rotate intermittently, and while the forming drum is stopped, a reciprocating plug is pushed into the cavity of this forming drum to perform the main forming of the thermoplastic sheet. You can also do this.

In the present invention, the thermoplastic sheet also includes a thin film-like sheet.

[Example] With reference to the drawings, an example of the method for molding a thermoplastic sheet according to the present invention will be described together with a blister packaging device to be used.

As shown in Figure 1, the packaging device used in this example is
Forming phase sheet supply section 10, tension applying section 2°, pocket forming section 30, content filling section 40, and sealing section 50
and the trimming section 60 are arranged in this order.

The forming sheet supply unit IO includes a feed roll 12 around which a thermoplastic sheet 11 is wound, and a guide roll 13.

The tension applying section 20 includes a first guide roll 21, a brake roll 22, and a second guide roll 23. In order to increase the contact area of the thermoplastic sheet 11 with the brake roll 22, the first guide roll 21 is placed on the second guide roll 23 side so that the thermoplastic sheet 11 is wound around the outer peripheral surface of the brake roll 22. establish. This brake roll 22 is, for example, a roll equipped with a powder brake.

This brake roll 22 applies tension to the thermoplastic sheet 11, which is pulled by the rotation of the forming drum 31.

As shown in FIG. 2, the pocket molding section 30 includes a rotary molding drum 31, a rotary roll plug 32 disposed on the upper part of the molding drum 31, and an approximately Infrared heater 3 provided over half the circumference
3.

As shown in FIGS. 2 and 3, this forming drum 31 is
It has a cylindrical shape, and a plurality of cavities 34 for forming pockets 1 and suction holes 35 for adsorbing thermoplastic sheet [1] are formed at predetermined intervals on its outer peripheral surface. As shown in the sectional view of FIG. 4, these cavities 34 are provided with a heat insulating material layer 36 made of polyimide, for example, with a thickness of 1 mm, at their peripheral edges. The dimensions of these cavities 34 correspond to pockets 1 for accommodating, for example, No. 3 pharmaceutical capsules. The suction holes 35 are formed in the shape of (+) and (-) shaped grooves in a portion of the outer peripheral surface of the molding drum 31 where the cavity 34 is not formed. Also, inside this molding drum 31, there are a plurality of small holes 34 formed at the bottom of the cavity 34.
A vacuum communication hole 37 communicating with A and a vacuum communication hole 38 communicating with the suction hole 35 are formed, and these vacuum communication holes 37.
38 is in communication with a vacuum suction device (not shown). Regarding the cavities 34, the degree of vacuum can be adjusted for each cavity 34 located in the direction (axial direction) perpendicular to the rotational direction of the forming drum 31. The cavity 34 into which the plug 39 is fitted is vacuumed at a vacuum level equal to or greater than the vacuum level of the other cavities 34 .

As shown in FIG. 2, the roll plug 32 has a cylindrical shape, and a plurality of plugs 39 having a shape that fits into the cavity 34 are formed at predetermined intervals on the outer peripheral surface thereof. As shown in FIG. 5, these plugs 39 are formed so that the upper surface 39A becomes slightly lower in the direction of rotation. For example, in the case of the cavity 34 for a No. 3 capsule,
At its leading end it is slightly lower than at its rear end, for example 0.
It is 5mm lower. With such a configuration of the plug 39, the upper surface of the molded pocket l can be made flat. The plug 39 is an Al plug whose surface is coated with Teflon (trade name), which is a fluororesin, but the Al plug can also be used as is. A built-in heater (not shown) for heating is provided inside the roll plug 32. In addition, this roll plug 32
The diameter of can be set arbitrarily.

As shown in FIG. 1, the content filling unit 40 includes a half slitter 41 that cuts the thermoplastic sheet II in half by perforations in the moving direction, and fills the pocket 1 with the content, such as a pharmaceutical capsule. A feeder 42 is provided.

The seal portion 50 includes a feed roll 52 on which a mount 51, for example, A7 foil is wound, and two guide rolls 53.
54, two sealing rolls 55, 56 for sealing the thermoplastic sheet 11, and a sealing roll 57.
Equipped with.

The trimming section 60 includes a curl removing device 61, two guide rolls 62 and 63, and a half slitter 6 that cuts the thermoplastic sheet 11 in half along the width direction by perforations or the like.
4, three guide rolls 65, 66, 67, and mount 5
A punching machine 68 is provided for punching out the heat-sealed thermoplastic sheet 11 into the external shape of the product.

Next, a blister packaging method including a method for forming the thermoplastic sheet 11 into the pocket 1 using the blister packaging apparatus having the above configuration will be described.

As shown in FIG. 1, the thermoplastic seam 1 is paid out from the payout roll 12 of the forming sheet supply section 10, is fed to the brake roll 22 of the tensioning section 20 via the guide roll 13. Thermoplastic sheet 11 is fed via roll 23 to forming drum 31 . At this time, a force is applied to the thermoplastic sheet 1-11 by the brake roll 22 to resist the bowing force caused by the rotation of the forming drum 31, and a predetermined tension is applied to the thermoplastic sheet 11. This tension is 0.2kg/cm~2.4kg/
cm, so that if the width of this thermoplastic sheet is, for example, 215 mm, then 5 k
A tension of about g/215 mm to 50 kg/215 ++ on will be applied. This tension is 0.2
If it is smaller than kg/cm, it is also 2 or 4 kg/cm.
If the size is larger, wrinkles will occur more frequently between the PTP molded product and the pockets.

Next, as shown in FIG. 2, the thermoplastic sheet [1] is supplied to the pocket forming section 30 and preformed. The forming drum 31 of the pocket forming section 30 is heated by an infrared heater 33, and the heating temperature is preferably 30°C to 80°C, preferably 50°C to 60°C. If the heating temperature is lower than 30°C or higher than 80°C, the molded product will shrink undesirably. The thermoplastic sheet 11 is in close contact with the forming drum 31 due to the tension applied thereto and the vacuum suction from the suction holes 35 in this forming drum 31, and in this state, the thermoplastic sheet 11 is in close contact with the forming drum 31 through the vacuum communication hole of the cavity 34. A vacuum is drawn from 37 into the cavity 34 . This degree of vacuum is
It is preferable to set the degree of vacuum to 400 mm+Hg or more and up to 760 mmHg. Here, the degree of vacuum is a value indicating the degree of vacuum as a difference from standard atmospheric pressure. If vacuum suction is not performed through the suction hole 35, wrinkles will increase between the molded product and the pockets, which is undesirable. At this time, the obtained pocket 1 is not a completely molded product that follows the shape of the cavity 34, but when the depth of the fully molded product is taken as 100%, the pocket 1 is 50%
It is a semi-molded product with a depth of less than %. The degree of molding of such a semi-formed pocket 1 can be controlled by appropriately adjusting the temperature of the infrared heater 33, the molding speed, and the degree of vacuum.

Next, as shown in FIG. 2, the semi-molded thermoplastic sheet 11 having the pockets 1 is sent to the position of the roll plug 32 by the rotation of the forming drum 31, and is then fully formed.

At this time, the roll plug 3 is heated by a built-in heater (not shown).
2 is heated to a predetermined temperature. This roll plug 32
The heating temperature should be between 40°C and 130°C.
If it is lower than 0°C or higher than 130°C, the shape of the molded product will be poor and the releasability of the molded product will be poor, which is not preferable. Furthermore, the thermoplastic sheet 11 is vacuumed at a vacuum level of 600 mmHg or more immediately before the plug 39 is fitted into the pocket l. The degree of vacuum in this main molding is set to be equal to or greater than the degree of vacuum in preforming when compared with the degree of vacuum in preforming. With this semi-formed pocket 1 being vacuum-suctioned into the cavity 34, the plaque 39 of the rotating roll plug 32 is fitted into the cavity 34, and the pocket 1 is completely formed.

Next, as shown in FIG. 1, the thermoplastic sheet 11 with the pockets l formed thereon is sent to a filling section 40, where a half slitter 41 cuts the thermoplastic sheet 11 in half in the direction of movement. Cutting and filling of the contents into the pocket l by the feeder 42 is performed.

Next, the thermoplastic sheet 11 with the contents filled in the pocket 1-1 is sent to the sealing section 50. Feeding roll 52
For example, Al foil, which is the mount 51, is used as the sealing roll 5.
5.56 and the seal receiver are fed to a roll 57 where the thermoplastic sheet hll and the backing paper 51 are heat sealed.

The sealed thermoplastic sheet 11 is then sent to a trimming section 60. Here, the curl is removed by the curl removing device 61, the thermoplastic sheet [1 is cut in half in the width direction by the half slitter 64, and the unit packaging surface is punched by the punching machine 68 to obtain a blister packaged product.

Experimental Example In the blister molding apparatus and molding method according to the above example, an FTP blister molded product was manufactured by setting specific conditions as follows.

Thermoplastic sheet: Three types of sheets with different materials and thicknesses were used.

Material and thickness: (1) Highly transparent unstretched polypropylene sheet [Idemitsu Purelay MG-100 (product name)], thickness 0.2m (2) PP/PCTFE/PP laminated sheet, thickness 0.2m.
32ff1m (3) PVDC/PCTFE/PP laminated sheet, thickness 0.32n+m Molding drum: Insulating material layer around cavity periphery...Temperature of polyimide molding tram...60°C Cavity dimensions...No. 3 Dimensions for capsule Forming speed: lom/min Plug: Material: Teflon-coated Al plug Slope of the plug surface: The tip of the plug is 0.5 mm lower than the rear end in the roll tangent direction. Temperature...45°C Clearance between plug and cavity...0.25m
m Preforming: Approximately 2 mm from the surface of the center of the cavity
The pocket was semi-formed to a depth of .

Immediately before the main molded nib plugs were fitted into the cavities, the cavities were vacuumed at the vacuum level for the main molding.

The No. 3 capsule-shaped blister package produced in this experimental example had good transparency for all three types of thermoplastic sheets used. In addition, the wall thickness of the top of pocket l is 70% or more of the thickness of thermoplastic sheet l,
The wall thickness distribution was good. Therefore, even if the sheet is made thinner, a good molded product can be obtained. Moreover, even at a molding speed of 10 m/min, good molding is possible, and high-speed molding is possible.

Also, the temperature of the forming drum is 600C, and the temperature of the plug is 4
Since the temperature is 5° C. and low-temperature molding is possible, heating energy can be reduced. Furthermore, the pockets were formed using three types of thermoplastic sheets [1] with different materials and thicknesses.
Regardless of the molded product, there are no problems with wall thickness, etc., and the present molding method can be applied to all types of thermoplastic sheets.

Using the highly transparent unstretched polypropylene sheet (thickness 0.21nlT+) as a thermoplastic sheet, the thickness of the top of the pocket l according to Experimental Examples 1 to 4 molded under each condition was measured, and the transparency The results of evaluating the mold reproducibility are shown in Table 1 below. Moreover, Comparative Examples 1 to 3 are also shown. In the same table, ○ for evaluation is good, × for mold reproducibility
indicates that it could not be formed into a pocket. The tension applied to these sheets was l-0k.
g/cm.

The packaging device used in this embodiment includes the forming sheet supply section 10 in the first embodiment, the tension applying section 20, the pocket forming section 30, the content filling section 40, and the sealing device. The tension applying section 20 and the pocket forming section 30 have the following configuration.

That is, as shown in FIG. 6, the tension applying section 20 includes a first guide roll 21, a brake roll 22, and a dancer roll 27 suspended between two rolls 25 and 26.
, intermediate guide roll 28 , and second guide roll 23
Equipped with. By adjusting the weight of the dancer roll 27, a predetermined tension is applied to the intermittently supplied eight plastic sheets 11. Further, while the thermoplastic sheet 11 is continuously supplied from the forming sheet supply section 10 by the dancer roll 27, the pocket forming section 30
The slack caused by intermittent feeding is adjusted.

As shown in FIG. 6, the pocket molding section 30 includes a rotary and intermittently driven molding drum 3■, a reciprocating plug 71 disposed on the upper part of the molding drum 3■, and a molding drum 3■ on the outer circumferential surface of the molding drum 3■. An infrared heater 33 is provided near the molding drum 31 and can move forward and backward with respect to the forming drum 31.

The plug 71 is supported by a plug support 72 and is configured to be movable forward and backward into the cavity 34 of the forming drum 31 by a drive mechanism 73 such as a combination of a motor and an eccentric cam or a cylinder. This plug 71 is
An oxide film is formed on the surface of the body made of A1, or a body made of A1 is coated with Teflon (trade name). The plugs 71 of this embodiment are arranged in two rows in the rotational direction of the forming drum 31. A built-in heater (not shown) is provided in the plug support 72. Further, as shown in FIG. 7, the plug 71 and the cavity 3 at the opening of the cavity 34 when the plug 71 is lowered to the bottom dead center.
It is preferable that the clearance C between the sheet 11 and the sheet 11 is from (thickness of the sheet 11) to (thickness of the sheet 11 + 150 μm). If the clearance C is larger than this, the plug 71
The slope of the side wall portion of the plug 71 becomes large, and the shape of the plug 71 cannot be reproduced well. Also, the sheet 11 is placed between the forming drum 31 and the feeder 42 via a guide roll 43.
In order to apply a predetermined tension to the
A dancer roll 46 suspended between them is arranged.

Next, a blister packaging method using the blister packaging apparatus of this embodiment will be explained. In this embodiment as well, the pocket 1 is formed in substantially the same steps as in the first embodiment.

That is, as shown in FIG. 1, the plastic sheet ll fed out from the feeding roll 12 is supplied to the brake roll 22 and dancer roll 27 of the tension applying section 20 as the forming drum 31 is intermittently driven, and is further Guide roll 28.2
3 to the forming drum 31.

At this time, the thermoplastic sheet 11 has a dancer roll 27
Depending on the weight of 0.2kg/cm~2.4kg
A tension in the range of / am is applied.

Next, as shown in FIG. 2 (refer to the structure of the forming drum 31) and FIG. 6, the thermoplastic sheet H1 is supplied to the pocket forming section 30 of the forming drum 31 and preformed. The molding drum 31 is heated to 30°C to 80°C by an infrared heater 33.
is heated to. In addition to being under tension in the forming drum 31, the thermoplastic sheet 11 is
By being vacuum-suctioned from the suction hole 35, it comes into close contact with the molding drum 31, and in this state, it is vacuum-suctioned from the vacuum communication hole 37 of the cavity 34 and sucked into the cavity 34. This degree of vacuum is 400mm Hg ~ 760m
m Hg. This reduces the depth of the complete molded part to 10
When it is 0%, a semi-molded product with a depth of 50% or less is molded.

Next, as shown in FIG. 6, the thermoplastic sheet Ml having the pocket 1 of the semi-molded product is sent to the position of the reciprocating plaque "71" with the intermittent rotation of the molding drum 31, and While the plug 71 is stopped, the plug 71 is lowered, pushed into the cavity 34, and is finally formed into the pocket L. In this actual molding, the thermoplastic seam [1 is inserted into the three plugs into the pocket L-1. 600mm Hg from just before mating
Vacuum suction is performed at a vacuum level higher than that. At this time, plug 7
The approach speed of 1 should be 5cm/see or more,
If it is slower than this, the top thickness (thickness at the top) of pocket 1, which is the molded part, will increase. Further, the stop time of the plug 7i at the bottom dead center is preferably 0.2 seconds or more; if it is shorter than this, the mold reproducibility of the pocket 1 in the molding section 30 will deteriorate.

Furthermore, the heating temperature of this plug 71 is 20°C to 50°C.
If it is lower than 20°C, the top thickness of the molded part will increase, and if it is higher than 50°C, the releasability of the molded part will be poor, which is not preferable.

After this, as in the first embodiment shown in FIG.
The thermoplastic sheet 11 having been molded is filled with the contents in the filling part 4.
0 and the sealing section 50, and further to the trimming section 60, where the blister packaged product of this embodiment is manufactured.

Experimental example In the blister molding apparatus and molding method according to the second embodiment, FTP was performed with specific conditions set as follows.
A blister molded product was manufactured.

Thermoplastic sheet: (1) Highly transparent unstretched polypropylene sheet [Idemitsu Pure Ray MG-200 (product name)], thickness 0.15 mm (
2) Same, thickness 0.2mm Molding drum: Heat insulating layer around cavity periphery...Temperature of polyimide molding drum...30°C, 70°C Molding cycle...1
00 shots/min Plug: Material: AN plug with oxidized surface Plug shape: No. 3 capsule shape plug Temperature: 30°C, 80°C Clearance to plug cavity: 300
μm, 400 μm Plug entry speed...3.3 cm/sec, 8.
6 am/sec bottom dead center resting time - 0.25 sec,
0.14 sec preforming: A pocket was semi-formed at a depth of about 2 mm from the surface of the central part of the cavity.

Immediately before the main molded nib plugs were fitted into the cavities, the cavities were vacuumed at the vacuum level for the main molding.

For each Experimental Example 5 to 13, the mold releasability from the plug and the mold reproducibility of the plug shape were evaluated, and the results of measuring the top thickness and side wall thickness of the obtained molded product (pocket) are shown in the table below. −
Shown in 2. Comparative examples are also shown. In the same table, ○ in the column of mold releasability from the plug indicates good mold releasability.
△ indicates that the mold is released, but it sticks to the plug, ○ in the mold reproducibility column is good, △ indicates that some shrinkage occurs, and × is 10%.
Each shows that the above contraction occurs. The tension applied to these sheets was 1.0 kg/
cm.

According to Table 2, according to this example, a good molded product can be obtained even when the temperature of the molding drum 31 and plug 71 is 30°C, and low temperature molding is possible, thereby reducing heating energy. . Also, the entry speed of the plug 71 is 8.6 c
Even at a high speed such as m/sec, by adjusting other conditions, it is possible to improve the releasability from the plug 71 and the reproducibility, so high-speed molding is possible. Furthermore, since the wall thickness especially at the top of the pocket 1 becomes thicker and the wall thickness distribution becomes better, a good molded product can be obtained even if the sheet 11 is made thinner.

In the first embodiment, the brake roll 22 is used in the tension application section 20 to apply tension to the thermoplastic sheet 11, but this tension application mechanism may have another configuration. For example, the present applicant
As proposed in No. 578, a structure in which a ring fixed to the outer periphery of the rubber roll is used as a brake rod to perform braking may also be used.

In addition, in the above embodiments (first and second embodiments), in order to be able to vacuum the cavity 34 into which the plug 39 is fitted in the main molding with a degree of vacuum greater than the vacuum degree of the other cavities 34, Although the configuration is such that the degree of vacuum can be adjusted for each cavity 34 located in a direction (axial direction) perpendicular to the direction of rotation of the circumferential surface of the molding drum 31, the cavity 34 into which the plug 39 is fitted can be adjusted between the other cavities. In this case, there is no need to provide a structure that can adjust the vacuum degree for each cavity 34. However, by making the degree of vacuum adjustable for each cavity 34 in the lateral direction in this manner, it becomes possible to control the degree of vacuum more preferably in order to improve moldability.

In the above embodiment, as a heating means for the plug 39.71,
Although the built-in heater is provided, an infrared heater may be provided near the roll plug 39° 71, as in the case of heating the forming drum 31.

Further, in the above embodiment, the material of the heat insulating layer 36 formed at the peripheral edge of the cavity 34 is polyimide, but other heat insulating materials can be arbitrarily selected.

Further, in the above embodiments, the case where a blister packaged product is manufactured is explained as an example, but the present invention may be applied to a process up to simply molding a thermoplastic sheet having pocket-shaped recesses.

[Effects of the Invention] According to the method for forming a thermoplastic sheet according to the present invention, pockets can be favorably thermoformed regardless of the material and structure of the thermoplastic sheet.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a blister molding device used in the first embodiment of the present invention, FIG. 2 is a front view of essential parts of this molding device, and FIG.
The figure is a perspective view of the forming drum, FIG. 4 is a sectional view of the cavity of this forming drum, FIG. 5 is a sectional view of the main part of the plug, and FIG.
The figure is a front view of the main parts of the blister molding apparatus used in the second embodiment, and FIG. 7 is a sectional view of the main parts of the plug and cavity according to the second embodiment. 1... Pocket, IO... Forming sheet supply section, 1
1... Thermoplastic sheet, 20... Tension applying section, 22
...Brake roll, 27...Dancer roll, 3
0... Pocket shape part, 31... Molding drum, 32
...Roll plug, 33...Infrared heater, 34.
...Cavity, 35...Suction hole, 36...Insulating material layer, 39...Plug, 40...Filling part with contents, 5
0... Seal part, 60... Trimming part, 71...
- Retractable plug.

Claims (3)

[Claims] (1) A thermoplastic sheet molding method in which a thermoplastic sheet is supplied to a molding drum to thermoform pockets, the thermoplastic sheet being brought into close contact with a molding drum having a cavity with a heat insulating layer formed on the periphery. , a step of preforming the thermoplastic sheet into the cavity by vacuum suction from the cavity side of the molding drum while externally heating it; A method for forming a thermoplastic sheet, comprising the step of main forming using a plug while applying vacuum suction from the cavity side. (2) In the method for forming a thermoplastic sheet according to the first aspect, a forming drum is continuously driven to rotate, and a rotary plug is pushed into a cavity of the forming drum to perform main forming of the thermoplastic sheet. Features a thermoplastic sheet molding method. (3) In the method for forming a thermoplastic sheet according to claim 1, the forming drum is intermittently driven to rotate, and while the forming drum is stopped, a reciprocating plug is pushed into the cavity of the forming drum. 1. A method for forming a thermoplastic sheet, comprising main forming the thermoplastic sheet.