JPH04168031A - Forming mold of resin container and forming method used thereof - Google Patents

Abstract

PURPOSE:To improve forming efficiency by a method wherein a male mold, in which a thin plate for forming the rim of the bottom of a container is protrusively provided on the bottom of a mold surface for forming a container main body, and a female mold for vacuum forming, in which a groove for inserting said thin plate for forming the rim of the bottom is provided on the bottom of a mold surface for forming the container main body and, at the same time, suction ports are provided at the inner surface of the groove, are equipped in the forming mold concerned. CONSTITUTION:Under the condition that a male mold 1 and a female mold 2 are heated, thermally softened thermoplastic resin sheet (a) is arranged between both the molds. Next, by moving the male mold 1 towards the female mold 2 so as to let a thin plate 3 push the sheet (a) in a groove 4, respectively the bottom of the male mold 1 is fixed through the sheet (a) by pressure to that of the female mold 2, the thin plate 3 to the peripheral side face in the groove 4 and the peripheral side face of the male mold 1 to the inner side face of the female mold 2 so as to thermoform the sheet (a). Next, through suction ports and a discharge passage 12, the interior of the groove 4 is evacuated to the direction indicated with the arrow A with a vacuum pump or the like so as to bring the sheet (a) into close contact with the inner surface of the groove 4 in order to form the sheet (a). After forming, the male mold 1 is stripped from the E female mold 2 so as to lower the temperature of the female mold 2 with a cooling device or the like and to cool and solidify the sheet (a) in order to obtain a formed article 6 having the rim 5 at its bottom. Thus, the manufacturing process of the resin container is simplified and its forming efficiency can be improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a resin container mold for molding food containers such as bowls and trays having string tails using a thermoplastic resin sheet, and a mold for molding the same. Regarding the molding method used.

<Prior art and problems to be solved by the invention> As a mold for molding a food container having a string end at the bottom using a thermoplastic foam resin sheet, a mold for molding a resin container is disclosed in Japanese Patent Application Laid-open No. 59
Those shown in Japanese Patent Publication No. 45113 and Japanese Patent Publication No. 1-34135 were known. In other words, these molds have a movable thread tail molding part in the male mold or the female mold, and a heat-softened thermoplastic resin sheet is placed between the male mold and the female mold to connect the male mold to the female mold. The container body is formed by crimping the container body, and then the thread end forming section is moved to form a thread end at the bottom of the container main body.

The mold for molding such resin containers has a movable string end molding part on either the male or female mold, which complicates the structure of the mold, leading to breakdowns and reducing molding efficiency. There was a problem that the mold itself was expensive.

Furthermore, the molding method using such a mold requires two steps: molding the container body and molding the end of the thread, resulting in a long molding cycle and poor productivity. was there.

The present invention has been made to solve the above-mentioned problems, and provides a mold for molding a resin container and a molding method using the same, which can mold a container body and a thread end in a step. It is intended to.

Means for Solving the Problems> The mold for molding a resin container of the present invention comprises a male mold in which a thin plate for thread tail molding is provided protruding from the bottom of the mold surface forming the container body, and a thin plate into which the thin plate is inserted. A groove for forming the end of the thread is provided at the bottom of the mold surface for forming the container body, and a female mold for vacuum forming is provided in which an air intake hole is provided on the inner surface of the groove.

Further, the method for molding a resin container of the present invention includes a male die in which a thin plate for forming a string tail is provided at the bottom protruding from the bottom of a mold surface for molding a container body, and a thin plate for forming a thread tail into which the thin plate is inserted. A heat-softened thermoplastic resin sheet is placed between the female mold for vacuum forming, which has grooves at the bottom of the mold surface for molding the container body, and then the male and female molds are inserted through this thermoplastic resin sheet. At the same time, a heat-softened thermoplastic resin sheet is pressed into the groove of the female mold using the thin plate, and air is sucked in through the intake hole provided on the inner surface of the groove of the female mold, so that the thermoplastic resin sheet is tightly attached to the inner surface of the groove. It is characterized in that the container body and the end of the thread are integrally molded.

Effects> [According to the molding mold of the present invention, the male mold is provided with a thin plate for forming the thread tail, and the female mold is provided with a groove for forming the thread tail into which the thin plate is inserted, and a groove for forming the thread tail into which the thin plate is inserted. Since it is for vacuum forming with air intake holes provided on the inner surface, when a heat-softened thermoplastic resin sheet is placed between the two and pressed together, the thermoplastic resin sheet is pushed into the groove by the thin plate. The thermoplastic resin sheet inside the groove is brought into close contact with the inner surface of the groove by sucking air into the groove through the intake hole, thereby forming a thread tail. At this time, unlike normal Matsuchimold molding, the thread end is formed using a thin plate, so the thread end can be formed at the same time as the container body is formed, and a movable part is provided in the male or female mold to form the thread end. There is no need to mold the butt, there is no need for complicated mold processing, the structure of the male and female molds is simple, and processes such as moving moving parts are no longer required, simplifying the molding process for resin containers. become Moreover, the molded thread ends are not thick and are favorable in terms of appearance.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a mold for molding a resin container according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a square-shaped male mold, and a cylindrical thin plate 3 for forming the thread end protrudes from the bottom of the male mold 1.

On the other hand, at the bottom of the mold surface for molding the container body of the female mold 2, a groove 4 for thread tail molding is provided at a position corresponding to the thin plate 3 of the male mold 1, into which the thin plate 3 is inserted. .

The thin plate 3 is made of a filler gauge, and is sandwiched between a core 7 and a gauge holding part 8, and the thin plate 3 is made to protrude from the bottom of the male die 1 by tightening the gauge holding part 8 to the core 7 side with a bolt 10. It is assembled into the male type 1 in this condition.

The thickness of the thin plate 3 is 0.05 to 2 mm, preferably 0.0
A material having a thickness of 5 to 1 mm is desirable in that it is possible to form a yarn end with an appropriate thickness and to have an appropriate strength.

Further, the protrusion length of the thin plate 3 is such that when the male die 1 and the female die 2 are fitted together with a thermoplastic resin sheet interposed therebetween, a thermoplastic resin sheet is placed between the tip of the thin plate 3 and the bottom portion 4a of the groove 4. Specifically, the protruding length of the thin plate 3 is set to 2 to 10 mm, preferably 5 to 8 mm, to form a gap approximately equal to the thickness of
The protrusion length of the thin plate 3 is set so that the tip of the thin plate 3 can be inserted to a position 0.1 to 1 mm away from the bottom of the groove 4, preferably 0.5 mm away.

The thin plate 3 is ring-shaped, and by arbitrarily setting its diameter, the size of the tail end formed at the bottom of the resin container can be freely set.

As shown in an enlarged view in FIG. 2, the gauge holding part 8 has a tapered peripheral wall whose diameter gradually narrows as it approaches the upper end, and corresponding to this tapered surface, the diameter gradually narrows as it approaches the upper end. If the structure is such that the taber ring 18 is interposed between the thin plate 3 and the gauge holding part 8, and the thin plate 3 is held by the core 7 and the gauge holding part 8, then by tightening the bolt 10, the gauge holding part 8 will be held. The thin plate 3 can be more firmly fixed to the male die 1 by moving in the direction of the arrow F in the figure and tightening the taber ring 18.

Note that the taber ring 18 may have a slit in the axial direction, or may be divided into a plurality of parts in the axial direction.

As shown in FIG. 1, the female mold 2 is fixed to a base 20 with bolts 11, and has a circular hole 21 at the bottom.
and a cavity core 2b which has a smaller diameter than the diameter of the hole 21 of the cavity 2a, is placed in the hole 21, and is fixed to the base 20 with bolts 11'. A groove 4 is formed by the peripheral wall of the cavity core 2b and the inner wall of the hole 21 of the cavity 2a.

In the bottom 4a of the groove 4, an intake hole 9 (indicated by a broken line) for sucking air into the inside of the groove 4 is provided at an appropriate part of the groove 4, and an exhaust passage 12 (indicated by a broken line) is provided below the intake hole 9. ) or consecutively.

The groove 4 has a width approximately equal to the thickness of the thermoplastic resin sheet when folded in half plus the thickness of the thin plate 3,
With the male and female molds fitted together via the thermoplastic resin sheet, a gap approximately equal to the thickness of the thermoplastic resin sheet is formed between the tip of the thin plate and the bottom 4a of the groove 4. More specifically, when the thin plate 3 has a thickness of 0.05 to 2 mm, preferably 0.05 to 1 mm, a protrusion length of 2 to 10 mm, preferably 5 to 8 mm, a width of 3 to 7 mm, preferably 4 to 8 mm.
5mm, depth 0.5-10.5mm, preferably 3-8
．． A diameter of 5 mm is preferable because it allows forming a thread end with an appropriate thickness and has an appropriate strength.

Examples of the thermoplastic resin sheet disposed between the male mold 1 and the female mold 2 include foamed resin sheets made of vinyl chloride, polyacrylate, polycarbonate, polyethylene, polystyrene, polyamide, acetate, polypropylene, and the like.

Next, a molding method for forming a foamed resin container using the male mold 1 and female mold 2 having the above configuration will be explained with reference to FIGS. 3 to 6.

(1) With the male mold 1 and the female mold 2 heated to a predetermined temperature, a thermoplastic resin sheet a softened by heating is placed between them as shown in FIG.

(21 As shown in Fig. 4, move the male mold 1 toward the female mold 2, and move the bottom of the male mold 1 toward the female mold 2 so that the thin plate 3 pushes the thermoplastic resin sheet a into the groove 4. At the bottom of the mold, the thin plate 3 is crimped to the circumferential surface in the groove 4, and the circumferential surface of the male die 1 is crimped to the inner surface of the female die 2 via a thermoplastic resin sheet a, and the thermoplastic resin sheet a is thermoformed. do.

(3) As shown in FIG. 5, a vacuum pump (not shown) or the like is used to connect the groove to
Air is drawn inside in the direction shown by arrow A to bring the thermoplastic resin sheet a into close contact with the inner surface of the groove 4, thereby forming the thermoplastic resin sheet a.

(4) After molding, as shown in FIG. 6, the male mold 1 is separated from the female mold 2, and the temperature of the female mold 2 is lowered by, for example, a cooling device, and the thermoplastic resin sheet a is cooled and solidified. , taken out from female mold 2. In this way, a well-shaped molded product 6 having thread tails 5 is obtained.

Next, the shaping of the tail end will be explained in detail using FIGS. 7 to 11.

As shown in FIG. 7, a flat thermoplastic resin sheet (a) that has been softened by heating is attached to the surface of the thin plate 3 by moving the thin plate 3 in the direction shown by arrow F in FIG. In this state, push it into the groove 4.

When the male die 1 and the female die 2 are crimped together, the thermoplastic resin sheet a fills the groove 4, but as shown in FIG. 9, if a gap 4b is created at the bottom corner of the groove 4. There is. Therefore, when air is taken into the groove 4 in the direction of arrow A in the figure through the intake hole 9, the thermoplastic resin sheet a comes into close contact with the inner surface of the groove 4, as shown in FIG. 10, and the gap 4b disappears. .

Next, by moving the thin plate 3 and taking out the thermoplastic resin sheet a, the yarn end 5 can be formed. As shown in FIG. 11, the end of the thread formed in this manner follows the shape of the groove 4, and has a stable shape with a horizontal bottom portion 5a.

In the mold having the above-mentioned configuration, the male mold 1 is provided with a thin plate 3 for forming the thread tail, and the female mold 2 is provided with a groove 4 for forming the thread tail into which the thin plate 3 is inserted. An intake hole 9 is provided on the inner surface of the beveled groove 4 to draw air into the inside of the groove 4, so when a heat-softened thermoplastic resin sheet is placed between the two and pressed together, the thermoplastic resin sheet is formed by a thin plate. Pushed into the groove. The thermoplastic resin sheet inside the groove adheres to the inner surface of the groove by drawing air into the groove through the intake hole.
Forms a thread tail. At this time, unlike normal Matsuchimold molding, the thread end is formed using a thin plate, so the thread end can be formed at the same time as the container body, and there is no need to provide a movable part in the male or female mold. , no complicated mold processing is required, and the structures of the male mold 1 and the female mold 2 are simplified. Therefore, the male mold 1 and the female mold 2 can be manufactured efficiently at low cost.

Moreover, complicated processes such as operating a movable part are no longer necessary, and the process of molding the resin container is simplified.

Furthermore, this shortens the molding cycle of the resin container.

In addition, in the above embodiment, the intake air in the groove 4 is
This is done through the two intake holes 9 provided in the first
As shown in FIG. 2, a plurality of intake holes 9' may be closed, or as shown in FIG. 13, four bottom portions 4a' may be formed of a breathable porous material. Furthermore, as shown in FIG. 14, an intake hole 9' may be formed on the circumferential side of the groove 4.

Further, in the above embodiment, a mold for molding a bowl-shaped foamed resin container and a molding method thereof are described, but this is not limited to the bowl shape, and various design changes can be made without changing the gist of the present invention. can be applied.

For example, a shallow dish 15 having a thread tail 13 shown in a top view and a cross-sectional view in FIGS. 15 and 16, and a thread tail shown in a top view and a cross-sectional view in FIGS. 17 and 18. 14
Various resin containers such as the rectangular tray 16 having the following shapes can be obtained.

Further, in the above embodiment, the cylindrical thread end 5 is formed at the bottom of the resin container by the cylindrical thin plate 3 and the corresponding groove 4, but the thin plate and the groove are discontinuous. If the shapes correspond to each other, then in the same way as in the above embodiment,
It is also possible to form leg pieces that protrude at arbitrary positions on the bottom of the resin container.

In addition, although the said Example demonstrated the foamed resin sheet, a non-foamed resin sheet can also be used.

Further, in the above embodiments, a case was described in which a male die and a female die were used in the press molding method, but a vacuum forming method or a double-sided vacuum forming method using a male die or a female die may also be performed.

<Effects of the Invention> As described above, according to the mold for molding a resin container of the present invention,
Since thread ends can be molded without using a movable mold for either the male mold or the female mold, the structures of the male mold and the female mold can be simplified, and the male mold and the female mold can be manufactured at low cost.

Furthermore, according to the method for molding a resin container of the present invention, a resin container with thread tails can be molded by simply pressing a thermoplastic resin sheet with a male mold and a female mold and vacuum forming it. The resin container manufacturing process can be simplified without going through any steps, the molding cycle can be shortened, and molding efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a molding die according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of essential parts of the mold, and FIGS.
The figure is a cross-sectional view for explaining the molding method for a resin container according to the present invention. 14 is an enlarged sectional view of the main part showing another example of a mold for molding a resin container, FIGS. 15 and 16 are a plan view and a sectional view showing another example of the resin container of the present invention, and FIG. 18 are a plan view and a sectional view showing still another example of the resin container according to the present invention. 1...male type, 2...female type, 3...thin plate, 4...
Groove, 5.13.14...Itojiri, 9...Intake hole Patent applicant: Sekisui Plastics Co., Ltd. Agent
Patent attorney Hirokatsu Kamei (2 idiots) Figure 2 1゜1...Male type 2...-Female type 3...Thin plate 4...Wi 9...Intake hole Figure 1 Do1/ 1... Male type 2... Female type 3... Thin plate 4... Clear Figure 3 Figure 4 Figure 1 Male type 2... Female type 3... Thin plate 4... Wei 5...・Thin end Figure 5 Figure 6 Figure 6 Thin plate 4 Groove 9 2. Intake hole Fig. 7 Fig. 8 Fig. 9 Fig. 1o Fig. 3... Thin plate 4... Groove 9... Intake hole Fig. 11 Fig. 12 Fig. 9' Fig. 13 Fig. 14 Fig. 15 Fig. 16

Claims (1)

[Scope of Claims] 1. A male mold having a thin plate for forming the thread tail protruding from the bottom of the mold surface forming the container body, and a groove for forming the thread tail into which the thin plate is inserted to form the container body. A mold for molding a resin container, comprising a female mold for vacuum molding, which is provided at the bottom of the mold surface and has an intake hole on the inner surface of the groove. 2. A male mold with a thin plate for forming the thread tail protruding from the bottom of the mold surface for molding the container body, and a groove for forming the thread tail into which the thin plate is inserted on the mold surface for molding the container body. A heat-softened thermoplastic resin sheet is placed between the female mold for vacuum forming provided at the bottom, and then the male mold and female mold are crimped together via this thermoplastic resin sheet, and at the same time the grooves of the female mold are A heated and softened thermoplastic resin sheet is pushed into the container body using the thin plate, and air is sucked in through the intake hole provided on the inner surface of the female groove to bring the thermoplastic resin sheet into close contact with the inner surface of the groove, thereby integrating the container body and the thread end. A method for molding a foamed resin container, characterized by molding the container into a foamed resin container.