JP2000167919A - Method and device for manufacturing plastic container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a container which is sufficiently proof against high temperature sterilization, limiting residual molding strains at any area of the container including a flange thereof. SOLUTION: The method for manufacturing a plastic container comprises a heating step 18 for heating the molding region of a blank which is blanked out of a thermoplastic sheet, a molding step 20 for molding the molding region of the heated blank into a predetermined container shape, and a flange annealing step 26 for removing molding strains remaining in a flange part outside the molding region of the blank by cooling the flange part after heating it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a plastic container having a flange, and more particularly to a blank formed by punching a thermoplastic sheet made of polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, or the like, into a predetermined shape. And a method for manufacturing the container.

[0002]

2. Description of the Related Art Conventionally, there have been proposed various techniques for forming a container having a predetermined shape by using a blank punched from a plastic sheet. In general, the outer edge of a blank serving as a flange in a formed container is heated. Instead, only the central molding region is heated.

For example, according to the molding techniques described in Japanese Patent Publication No. 6-88328 and Japanese Patent Laid-Open Publication No. 2-150338, heating is performed by placing a blank in an oven having a temperature equal to or higher than the melting point of the plastic for a predetermined time. A so-called indirect heating method is employed, in which the outer edge of the plastic blank is maintained and fixed in the solid phase region, and only the central molding region is heated to the molten phase to form a retortable container.
According to this prior art, special measures are taken to keep the outer edge of the blank in the solid state zone, but furthermore, the blank kept in the oven for a long time is heated to a high temperature over the entire molding area. Therefore, the outer edge portion tends to expand and change due to heat conduction, and a cooling means is used in combination to suppress this.

[0004]

In the above prior art, a molding region heated to a molten phase through a heating step is molded into a predetermined container shape. As a result of the accumulation of internal stress, molding strain remains. In particular, in this prior art, the outer edge of the blank is actively cooled, so that a large strain tends to remain at the outer edge. For this reason, when high-temperature sterilization such as retort sterilization is performed after enclosing food such as rice, various dishes, desserts, etc. in a container, molding strain remaining on the outer edge appears as a waving phenomenon of the flange, and the product value Is significantly reduced.

[0005] The same phenomenon is not limited to the case of employing the indirect heating method as in the prior art described above.
This was also occasionally found when employing the direct heating method proposed in -250122 and Japanese Patent Application No. 10-219721. In other words, in the molding method using the direct heating method, when heating a blank punched from a thermoplastic plastic sheet, a heating plate is applied from above and below to the molding area inside the blank, leaving an outer edge of the blank corresponding to the flange of the container. After heating to a predetermined temperature that can be thermoformed by plastic, the heated blank molding area is molded into a predetermined container shape, but also in this case, at the blank outer edge that is not directly heated by the hot platen Molding distortion is apt to remain.
When steam sterilization was performed at a high temperature of 0 ° C. or more, container deformation such as waving of the flange portion was often observed.

Although it is conceivable to use a thick blank in order to eliminate the waving phenomenon of the flange, it is not practical because of a great disadvantage in cost.

[0007] Accordingly, the present invention suppresses the residual molding strain in all parts including the flange portion of the container, regardless of whether the method is the direct heating method or the indirect heating method, and sufficiently withstands high-temperature sterilization. It is an object of the present invention to produce a container that can be obtained. Therefore, the present invention is particularly useful as a technique for manufacturing a container in which high-temperature sterilization is performed after filling the contents.

[0008]

According to the present invention, there is provided, according to the present invention, a heating step of heating a blank forming area punched from a thermoplastic sheet, and a step of forming the heated blank. A molding step of molding the region into a predetermined container shape, and a flange annealing step of removing the molding strain remaining in the flange portion by heating and cooling the flange portion left outside the blank molding region, and A method for producing a plastic container is provided.

In the flange annealing step, the blank is heated to a temperature higher than the softening point of the plastic material and then cooled to a temperature lower than the softening point. Regarding the heating, specific conditions are determined by a correlation between temperature and time. Generally, when heating to a temperature near the melting point of the blank material or a temperature equal to or higher than the melting point, the forming distortion of the flange portion can be removed by a short heat treatment. If the blank material is heated to a temperature above the softening point but relatively low,
By performing the heat treatment for a certain period of time, it is possible to remove the molding distortion of the flange portion.

According to another aspect of the present invention, there is provided a method of manufacturing a plastic container, comprising: a heating step of heating a blank forming area punched from a thermoplastic sheet; and forming the heated blank forming area into a predetermined container shape. Forming step, a flange heating step of heating the flange portion left outside the blank forming area above the melting point of the blank, and a flange forming step of cooling after forming the heated flange part into a predetermined shape, Have. According to this method, the molding distortion in the flange portion is removed by performing the flange heating step and the flange forming step, and the flange portion is formed into a predetermined shape such as a projecting flange or a skirt flange.

Further, according to the present invention, a heating means for heating a molding area of a blank punched from a thermoplastic sheet, a molding means for molding the molding area of the heated blank into a predetermined container shape, and a blank And a flange annealing means for removing the molding strain remaining in the flange portion by heating and then cooling the flange portion left outside the molding region of the plastic container.

According to another aspect of the present invention, there is provided a plastic container manufacturing apparatus for heating a blank forming area punched from a thermoplastic sheet, and forming the heated blank forming area into a predetermined container shape. Forming means, flange heating means for heating the flange portion left outside the forming area of the blank above the melting point of the blank, and flange forming means for cooling after forming the heated flange into a predetermined shape, Have. According to this device, the forming distortion in the flange portion is removed by the flange heating means and the flange forming means, and the flange portion is formed into a predetermined shape.

According to the present invention, a plastic container is thermoformed from an arbitrary plastic sheet, and the plastic sheet is made of a polyolefin resin such as polypropylene or polyethylene, a polystyrene resin, a polyamide resin, a polyester resin, or any of these. , A thermoplastic elastomer, a resin obtained by mixing various additives or inorganic fillers with 5 to 70% by weight thereof, and a gas barrier property of ethylene vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride and the like. A single-layer or multi-layer plastic sheet of an arbitrary thermoplastic resin material such as a resin having the same or a mixture of an inorganic filler and 10 to 80% by weight thereof can be used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plastic container molding apparatus according to one embodiment of the present invention will be described below with reference to the accompanying drawings. This molding apparatus is configured as an apparatus for continuously manufacturing a container 1 made of PP (polypropylene) as shown in FIG.

Referring to FIG. 1, a blank in the form of a circular flat plate punched from a PP sheet corresponding to the outer diameter of a container to be a final product is supplied to a shooter 11. In the present embodiment, the blank holders 12 for holding blanks are capable of placing two blanks in the transport direction and four blanks in the horizontal direction, and correspondingly, the four shooters 11 are arranged side by side in the horizontal direction. Has been established.

FIG. 2 shows the structure of the blank holder 12 of this embodiment. As described above, a total of eight blank holders 13 (four rows in the front row in the transport direction) are formed on a metal plate such as steel or stainless steel. A blank holding section 13a and four blank holding sections 13b) in the rear row in the transport direction are provided. Each blank holding portion 13 has a lower heating plate 19b (FIG. 6) in the heating process, and a mold 2 for defining the outer shape of the main body 2 of the container 1 as a final product in the molding process.
1 (FIG. 8) for inserting each of them.
4a is formed penetrating through the stainless steel plate, and a flange support portion 14b for mounting and housing a portion corresponding to the flange 3 of the container is formed above the stainless steel plate (see FIG. 4). 3).

The blank holder 12 is intermittently driven in a counterclockwise direction in FIG. 1 together with a conveyor 15 such as a chain conveyor whose drive is controlled by a drive control mechanism (not shown). A large number of blank holders 12 are connected to the conveyer 15 by an arbitrary connecting means in such a manner that the adjacent blank holders 12 are substantially in close contact with each other or are arranged with a slight space between each other. In FIG. 1, the blank holder 12 is a blank holder 12 (12 ') at a blank supply position described below and a blank holder 12 (12'') at a container removal position described later.
One is shown, and the rest is not shown.

The blank holder 12 (12 ') reaching the position below the chute 11 stops at this position for a predetermined time,
During that time, a blank is supplied from the shooter 11. The specific configuration of the supply means at this time is not limited in the present invention, but a blank supply means 16 as shown in FIG. 1 is used in this embodiment. The blank supply means 16 extends the suction cup 16a at the position shown in FIG.
The blank holder 13 is rotated in the clockwise direction in FIG.
a, the blank sucked by the suction cup 16a is released and accommodated by releasing the pressure, and this operation is repeated once again to supply the blank to the blank holder 13b in the row behind the same blank holder 12 in the transport direction. Have been. After the blank supply to the blank holding unit 13a is completed and before the blank supply to the blank holding unit 13b is started, the blank holder 12 is slightly advanced by the drive of the conveyor 15, and the blank holding unit 13b is sucked. When it reaches the position immediately below the device 16, it stops at this position for a predetermined time, and the blank is supplied to the blank holding portion 13b.

Since the unheated blank 10 supplied from the shooter 11 has a circular flat plate shape punched from the PP sheet, the outer edge corresponding to the flange of the container is placed on the flange support portion 14b. It is stored in the blank holding part 13 in a state (see FIG. 4). Since the blank 10 is slightly expanded and deformed by heat conduction in the next heating step, the blank 10 is preferably formed to have a slightly smaller diameter than the flange supporting portion 14b (that is, the outer diameter of the container flange 3 of the final product) (see FIG. 4). Thus, the outer edge of the blank 10 thermally expanded during heating can be brought into close contact with the inner wall of the flange support portion 14b.

A blank holder 12 for accommodating each blank 10 in a blank holder 13 is driven by a conveyor 15 and heated by a heating means 18 to heat the blank 10 to a predetermined temperature at which the blank 10 can be formed into a container shape of a final product. It is thrown into. As the heating means 18, an indirect heating method in which the blank holder 12 is held in an oven at a predetermined temperature for a predetermined time may be adopted, but in this embodiment, a heating means 18 of a direct heating method using a hot plate is employed. And as a heating device constituting the heating means 18 of the direct heating system,
A plurality (three in this embodiment) of substantially the same structure are installed in the blank holder transport direction, and these heating devices 18a to 18a are provided.
The heating temperature is gradually increased by 18c.

The heating temperature of the blank 10 in the heating step can be different depending on the use of the food container to be manufactured, that is, the contents contained in the container. For example, in the case of putting cooked rice (in the case of manufacturing a so-called packed rice cooker), after encapsulation, heat sterilization at a high temperature of 130 ° C. or more to completely kill the heat-resistant bacteria mixed in the cooked rice. In order to prevent the container from being deformed even when such high-temperature sterilization is performed, at least the final hot plate temperature is set to a temperature higher than the melting point of PP of 165 ° C.
It is preferable to heat 0a to a molten phase to eliminate molding strain remaining in the container after molding as much as possible. Depending on the contents, molding can be performed while the blank molding portion 10a is maintained in the solid phase region. In this case, heating is performed to a relatively low temperature that stops in the solid phase region.

As shown in FIG. 6, each of the heating devices 18a to 18c has an upper and lower heating plate 19a, 1a heated to a predetermined temperature.
9b and an elevating mechanism (not shown) for elevating and moving these hot plates. The blank holder 12 receiving the blank supply at the blank supply position is
When the heating device 18a advances by driving and reaches the first heating device 18a (first heating position), the heating device 18a stops at this position for a predetermined time, and the upper and lower heating plates 19a and 19b which have been receded from the transport surface of the blank holder 12 until then are moved up and down. And is brought into close contact with the upper and lower surfaces of the blank 10 held by the blank holder 13 of the blank holder 12 stopped at the first heating position for a predetermined time. In FIG. 6, the operating positions where the upper and lower hot plates 19a and 19b press the upper and lower surfaces of the blank 10 are shown by solid lines.
The retracted position is indicated by a virtual line.

When the blank heating at the first heating position is completed, the upper and lower heating plates 19a and 19b are retracted to the retreat position, and the blank holder 12 is moved together with the conveyor 15 by the second heating device 1
8b (second heating position), stop at this position for a predetermined time, perform blank heating by the second heating device 18b in the same manner as described above, and then perform blank heating by the third heating device 18c in the same manner. Heating is performed.

As described above, the outer edge portion 10b of the blank 10 corresponding to the container flange 3 is placed on the flange support portion 14b of the blank holding portion 13 and is formed at the center of the blank 10 formed on the container body 2. Only 10a is heated between the upper and lower hot plates 19a and 19b of the heating device to a temperature corresponding to the hot plate temperature. That is, the blank forming section 10a is gradually heated by the first to third heating devices 18a to 18c, but when high-temperature heat sterilization after filling the contents is required, such as a container for packed rice, The central portion, which is the molding region, is directly heated by the hot plate and heated to a temperature equal to or higher than the melting point. In this case, since the blank outer edge portion 10b is not in contact with the hot platen, it is usually maintained in the solid phase region.

Even if the outer peripheral portion 10b of the blank is maintained in the solid phase region, if it is not heated to a certain temperature, the mold reproducibility of the container is deteriorated, and a slight distortion tends to remain in the molded portion. In order to suppress this, as shown in FIG. 6, the lower heating plate 19b has a diameter dimension corresponding to only the blank forming portion 19a, and the upper heating plate 1
It is preferable that 9a has a diameter larger than this and which corresponds to the blank outer edge portion 10b.

The blank holder 12 that has passed through the heating step is driven by the conveyor 15 and is conveyed to a molding step of molding the blank molded portion 10a heated by the molding means 20 into a container body shape. As shown in FIGS. 7 and 8, the molding means 20 of the present embodiment includes a mold 21 having a cavity 21 a defining an outer shape of the container body 2, and a molding portion 10 a which cooperates with the cavity 21 a to form the container body 10. Plug 22 formed into two shapes, and clamp 2 for housing plug 22
3 and a first elevating mechanism for elevating and lowering the mold (not shown)
And a second elevating mechanism (not shown) for integrally and separately elevating and lowering the plug 22 and the clamp 23. The outer diameter of the clamp 23 is the blank holder 1.
3 is substantially the same as the inner diameter of the flange support portion 14b. Compressed air (for example, 3 to 8 kg)
/ Square cm) is introduced into the clamp. Further, a vacuum suction port 25 provided in the mold 21 is connected to a vacuum suction source (not shown) so that the inside of the cavity 21a can be vacuum suctioned during molding.

When such a molding means 20 is at the position shown in FIG. 7, the blank holder 12 for accommodating the blank 10 which has undergone the heating step comprises a mold 21 retracted downward, a plug 22 retracted upward, and a clamp 22. 23. Then, the blank holder 12 is stopped at this position for a predetermined time, during which the mold 21 is moved up by the first elevating mechanism and is inserted and fitted into the insertion portion 14a of the blank holding portion 13 so that the blank 10 is Outer edge 10b
While supporting the lower surface of the boundary portion from the lower portion to the forming portion 10a, the clamp 23 is moved down by the second lifting mechanism to clamp the blank outer edge portion 10a between the lower end of the clamp 23 and the bottom surface of the flange support portion 14b. In this state, the plug 22 is further lowered with respect to the clamp 23,
The working position during molding shown in FIG. 8 is obtained.

In the operating position shown in FIG. 8, the blank forming portion 10a heated to a temperature at which it can be thermoformed through the heating step is deformed into a concave shape as the plug 22 descends, and finally the cavity shape of the mold 21 is changed. Is formed into a shape corresponding to
At this time, since the blank outer edge portion 10b is sandwiched and fixed between the lower end of the clamp 23 and the bottom surface of the flange support portion 14b, even if the plug 22 is lowered, it is not deformed at all, and is left as it is. (FIG. 5) is formed.

The forming means 20 shown in FIGS. 7 and 8
In order to facilitate molding of the blank molded portion 10a into a predetermined shape particularly in a container in which the blank molded portion 10a is maintained in the solid phase region, compressed air is introduced from the compressed air inlet 24 during molding. A pressing force is applied to the blank forming part 10a together with the plug 22 from above, or the inside of the cavity is vacuum-sucked from the vacuum suction port 25 so that the blank forming part 10a is brought into close contact with the cavity 21a without any gap. Pressurized air introduction and vacuum suction may be used in combination.

FIGS. 7 and 8 show only one example of the molding means 20, and the present invention is not limited to this. Plug assist is useful to make molding easier,
In the case of a container in which the blank forming section is heated to a temperature higher than the melting point of the plastic material of the blank, such as a container for packed rice, the combination of the introduction of the compressed air and the vacuum suction without using the plug 22 or simply the compressed air It can be molded sufficiently only by introduction or vacuum suction alone.

As described above, the blank 10 is formed into a predetermined container 1 shape by the forming means 20, and after the forming step of cooling if necessary, the mold 21, the plug 22 and the clamp 23 are respectively moved to the first position. Then, the blank holder 12 is retracted to the retracted position shown in FIG. 7 by the second lifting mechanism, and the blank holder 12 stopped at the molding process position is advanced by driving the conveyor 15.

The blank holder 12 that has undergone the forming step is then subjected to a flange annealing step in which a hot plate is applied to the flange 3 and heated, followed by cooling to remove the forming distortion remaining on the flange. Referring to FIG. 9 together with FIG. 1, flange annealing means 26 for the flange annealing step includes heating means 27 for heating by bringing a hot platen 27 a into contact with the upper surface of flange 3, and flange 3 heated by heating means 27. And cooling means 28 for cooling by bringing a cooling board 28a into contact with the upper surface of the cooling plate 28a.

After the flange annealing step, the blank holder is moved to a position indicated by reference numeral 12 ″ in FIG.
The container 1 is taken out from all the blank holding parts 13 by 9. The blank holder 12 having the empty blank holding portion 13 is circulated and driven by the conveyor 15, and the blank holding portion 13 is moved to the blank holding portion 13 by the blank supply means 16 as described above at the position indicated by reference numeral 12 ′ in FIG. Blank supply is performed.

As described above, the steps of blank supply, blank heating, container forming, flange annealing, and container removal are successively performed in accordance with the driving of the conveyor 15, and the operation is repeated as one cycle. Things.

An example of the shape of a plastic container thermoformed according to the present invention is shown in FIG. 5. In order to prevent secondary contamination of food contents or to maintain sanitary conditions, plastic flanges are generally provided on the container flange 3. The cover material such as a film is heat-sealed. In this case, in order to improve the heat sealing property and the peeling property, the container flange 3 may be formed as a so-called projection flange in which irregularities are formed by projecting the surface side of the container flange 3. Further, in order to improve the flange rigidity of the container, the outer edge of the flat portion of the container flange 3 may be formed as a so-called skirt flange which is bent downward. Such flange forming may be performed simultaneously with forming the blank forming portion 10a into a predetermined container shape by the forming means 20 (this is described in detail in Japanese Patent Application No. 10-219721 by the present applicant). Means 18
When the outer peripheral portion 10b of the blank which is not directly heated by the heat treatment is formed, the distortion becomes large. Therefore, it is preferable to perform the flange forming at the same time in the flange annealing step.

FIGS. 10 and 11 show a flange forming means used in this case, and FIG. 10 shows a flange forming means 30a used for forming irregularities on the flange 3.
FIG. 11 shows a flange forming means 30b used when forming as a skirt flange. This flange forming means is installed in a step after the heating means 27 in FIG. 9 and cools the flange formed in the same step.

That is, in the forming means 20, the blank forming portion 10a is formed into a predetermined container shape, and the blank outer edge 1a is formed.
7b is pressed into contact with the lower end of the clamp 23 and the support surface of the blank holder 12, and is simply formed as a flat flange 3 as shown in FIGS. Since the blank outer edge 10b is not heated by the heating means 18,
Molding distortion may remain in the flange 3 molded at this stage, and distortion or waving may be observed.

After that, a flange annealing step is performed by the flange annealing means 26. The heating plate 27a of the heating means 27 (FIG. 9) is brought into contact with the upper surface of the flange 3 so that only the flange 3 is heated to a temperature higher than the melting point of the blank material. Heating,
Immediately thereafter, the forming means 30a (FIG. 10) or 30b
The protruding flange 3a (FIG. 10) or the skirt flange 3b (FIG. 11) by a molding die as shown in FIG.
After cooling, the flange is formed simultaneously with the flange annealing. In this case, the cooling board 28a preferably has a contact surface that matches the shape of the uneven flange 3a or the skirt flange 3b.

The present invention has a great feature in that the strain remaining after the container forming step is removed by the flange annealing step in the part of the flange that is not heated in forming the container from the plastic blank, and its operation and effect are demonstrated. For this purpose, a test was performed in the following manner.

[0040] PP multilayer sheet (PP / AD / EVOH)
/ AD / PP laminated sheet)
After heating a blank with a diameter of 0.8 mm and a hot plate from above and below (hot plate temperature is 165 ° C, 165 ° C and 180 ° C), one serving (raw rice) is introduced by introducing compressed air (6 kg / square cm) (plug assist). Into a container having a capacity and a shape suitable for accommodating cooked rice of 200 g), and steam sterilizing treatment is performed by repeating steam flashing at 140 ° C. for 6 seconds eight times without performing any flange annealing treatment. As a result, it was confirmed that significant waving deformation occurred in the flange. Similarly, even when the sterilization treatment was replaced with retort sterilization at 120 ° C. for 30 minutes, a remarkable flange waving phenomenon was similarly observed.

On the other hand, after the container formed in the same manner as described above was subjected to flange annealing treatment,
Steam sterilization treatment was performed by repeating steam flashing for 6 seconds for 8 times, and the degree of wavy deformation of the flange was visually evaluated. The condition of the flange annealing treatment is that the temperature of the hot platen 27a (FIG. 9) brought into contact with the upper surface of the flange is 150 to 2
The contact time (cooling time) of the cooling plate 28a (FIG. 9) at 25 ° C. is the same as the heating time, while changing the contact time (heating time) of the hot platen between 1 and 8 seconds while changing it in the range of 60 ° C. And Table 1 shows the results of visual evaluation of the degree of flange waving deformation of these containers.

[Table 1] Table 2 shows the results of visually evaluating the degree of wavy deformation of the flange in the same manner as described above, except that the sterilization treatment was replaced with retort sterilization at 120 ° C. for 30 minutes.

[Table 2] From the results in Tables 1 and 2, regardless of the heating time, by setting the temperature of the hot platen 27a to 160 to 260 ° C,
It has been demonstrated that the waving phenomenon of the flange can be effectively suppressed after the high-temperature sterilization treatment. The sheet thickness is 0.6mm
And 1.0 mm blanks, and the cooling temperature in the flange annealing treatment is 5 ° C and 40 ° C.
The same test was also performed for those treated in place of, but the evaluation results of the flange wavy deformation were substantially the same as those in Tables 1 and 2, and regardless of these conditions, 160 to
It was confirmed that flange annealing at a temperature of 260 ° C. was necessary to remove molding distortion of the flange and to suppress deformation of the container. Next, the container obtained in the same manner as described above except that the blank heating means was replaced with an indirect heating method in which the molding portion was heated to the melting region by the upper and lower infrastructure heaters while maintaining the outer edge portion of the blank in the solid phase region while maintaining the cooling thereof. Then, steam sterilization treatment and retort sterilization treatment were performed in the same manner as described above, and the flange waving deformation was visually evaluated. In this case, results substantially similar to those in Tables 1 and 2 were obtained. From these results, it has been proved that the flange annealing treatment after forming the container according to the present invention is useful not only for the direct heating method but also for the container formed by the indirect heating method. Further, a similar test was performed for a case where flange forming was performed simultaneously with flange annealing using a flange forming die as shown in FIGS. 10 and 11.
In this case, results similar to those in Tables 1 and 2 were obtained. From this result, the container flange 3 was connected to the projection flange 3a.
In the case of molding as a blank or a skirt flange 3b, the blank molding portion 10a is formed into a predetermined container shape, and then the flange 3 is formed.
It has been proved that by annealing and forming into a predetermined flange shape, it is possible to form a flange without distortion and waving. Although the preferred embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to these embodiments, and various modifications may be made within the scope of the claims. Can be.

According to the present invention, a container which is not heated in a thermoforming technique in which a blank forming area obtained by punching from a plastic sheet is heated by a direct heating method or an indirect heating method using a hot plate and then formed into a predetermined shape. Since the molding strain remaining in the flange portion is removed in the flange annealing step after molding, even if high-temperature sterilization is performed, a container deformation phenomenon such as flange waving does not occur. Since the strain of the flange portion accumulated during molding is completely removed in the flange annealing step after molding, the sheet thickness of the blank to be used can be reduced, and the cost merit is great.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a plastic container molding apparatus according to one embodiment of the present invention.

FIG. 2 is a perspective view of a blank holder used in the apparatus of the present embodiment.

FIG. 3 is a cross-sectional view showing a blank holding section of the blank holder.

FIG. 4 is a cross-sectional view similar to FIG. 3, illustrating a state in which a blank is supplied from a blank supply device to a blank holding unit of a blank holder.

FIG. 5 is a perspective view of a plastic container molded by the apparatus of the present embodiment.

FIG. 6 is a cross-sectional view illustrating a positional relationship between a heating unit and a blank held by a blank holding unit of a blank holder in the apparatus of the present embodiment.

FIG. 7 is a cross-sectional view illustrating a positional relationship between a forming unit and a blank held by a blank holding unit of a blank holder in the apparatus of the present embodiment before starting a forming process.

FIG. 8 is a cross-sectional view showing a positional relationship during a molding process between a molding means and a blank held by a blank holder of a blank holder in the apparatus of the present embodiment.

FIG. 9 is an explanatory diagram illustrating a schematic configuration and operation of a flange annealing unit in the apparatus of the present embodiment.

FIG. 10 is a cross-sectional view showing one example of a flange forming means used when performing flange forming simultaneously in a flange annealing step.

FIG. 11 is a cross-sectional view showing another example of the flange forming means used when performing flange forming simultaneously in the flange annealing step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic container 2 Container main body 3 Container flange 3a Projection flange 3b Skirt flange 10 Plastic blank 10a Blank molding part 10b Blank outer edge part 11 Shooter 12 Blank holder 13 Blank holding part 14a Mold insertion part 14b Flange support part 15 Conveyor 16 Blank supply means Reference Signs List 18 heating means 19a, 19b upper and lower heating plates 20 molding means 21 mold 21a cavity 22 plug 23 clamp 24 compressed air introduction port 25 vacuum suction port 26 flange annealing means 27 heating means 27a hot platen 28 cooling means 28a cooling plate 29 container taking out means 30a , 30b Flange forming means

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[Procedure amendment]

[Submission date] January 22, 1999 (1999.1.2
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

The blank holder 12 (12 ') reaching the position below the chute 11 stops at this position for a predetermined time,
During that time, a blank is supplied from the shooter 11. The specific configuration of the supply means at this time is not limited in the present invention, but a blank supply means 16 as shown in FIG. 1 is used in this embodiment. The blank suction means 16 extends the suction cup 16a at the position shown in FIG.
The blank holder 13 is rotated in the clockwise direction in FIG.
a, the blank sucked by the suction cup 16a is released by pressure release and accommodated, and this operation is repeated once again to supply the blank to the blank holding portion 13b in the rear row of the same blank holder 12 in the transport direction. Have been.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

The blank holder 12 that has passed through the heating step is driven by the conveyor 15 and is conveyed to a molding step of molding the blank molded portion 10a heated by the molding means 20 into a container body shape. As shown in FIGS. 7 and 8, the molding means 20 of the present embodiment includes a mold 21 having a cavity 21 a defining an outer shape of the container body 2, and a molding portion 10 a which cooperates with the cavity 21 a to form the container body 10. A plug 22 formed into two shapes and a clamp 23 for accommodating the plug
A first elevating mechanism (not shown) for elevating and lowering the mold;
A second elevating mechanism (not shown) for integrally and separately elevating and lowering the plug 22 and the clamp 23 is provided. The outer diameter of the clamp 23 is substantially the same as the inner diameter of the flange support portion 14b of the blank holding portion 13. A compressed air inlet 24 for introducing compressed air (for example, 1 to 8 kg / square cm) into the clamp at the time of molding is provided in the clamp 23.
Is provided. Further, a vacuum suction port 25 provided in the mold 21 is connected to a vacuum suction source (not shown) so that the inside of the cavity 21a can be suctioned at the time of molding.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

Continued on front page F-term (reference) 4F208 AA04 AA11 AA15 AA24 AC03 AG07 AG24 AH55 AH58 AM32 AR06 MA01 MA03 MB01 MC01 MC03 MC04 MG21 MH06 MH09 MJ22 MJ29 MK02 MW01

Claims (4)

[Claims] 1. A heating step of heating a molding area of a blank punched from a thermoplastic sheet, a molding step of molding the molding area of the heated blank into a predetermined container shape, and A flange annealing step of removing molding strain remaining in the flange portion by cooling after heating the remaining flange portion,
A method for producing a plastic container, comprising: 2. A heating step of heating a molding area of a blank punched from a thermoplastic sheet, a molding step of molding the molding area of the heated blank into a predetermined container shape, A flange heating step of heating the remaining flange portion to a temperature equal to or higher than the melting point of the blank, and a flange forming step of cooling the formed flange portion after forming it into a predetermined shape, and comprising a flange heating step and a flange forming step. A method for producing a plastic container, comprising: removing molding strain in a flange portion by passing through; and forming the flange portion into a predetermined shape. 3. A heating means for heating a molding area of a blank punched from a thermoplastic sheet, a molding means for molding the molding area of the heated blank into a predetermined container shape, and Flange annealing means for removing the molding strain remaining in the flange portion by cooling after heating the remaining flange portion,
An apparatus for manufacturing a plastic container, comprising: 4. A heating means for heating a molding area of a blank punched from a thermoplastic sheet; a molding means for molding the molding area of the heated blank into a predetermined container shape; Flange heating means for heating the remaining flange portion to a temperature equal to or higher than the melting point of the blank, and flange forming means for cooling after forming the heated flange portion into a predetermined shape, and having the flange heating means and the flange forming means An apparatus for manufacturing a plastic container, wherein molding distortion in a flange portion is removed and the flange portion is molded into a predetermined shape.