JPH0360657B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for molding a hinge portion and a mold for the same, and more specifically, the present invention relates to a method for molding a hinge portion and a mold for the same. The present invention relates to a method for molding a hinge portion having a bending groove and a mold for the molding.

<Prior Art> Conventionally, the above-mentioned hinge portion has been provided in, for example, a packaging container with a lid, such as a container for storing natto. Like container 1, container body 2 and lid 3
are integrally connected, and the lid body 3 is connected to the container body 2.
A hinge portion 4 is known that is provided in a bendable and fitable manner.

The hinge portion 4 is formed from a plurality of bending grooves 4a having a substantially V-shaped longitudinal section.

In the method of molding such a container, as shown in FIGS. 7 and 8, a foamed sheet S1 of thermoplastic resin such as a foamed polystyrene sheet is used, and integral molding consisting of a male mold 11 and a female mold 12 is performed. The foamed sheet S1 is sheet-molded using a compression molding means equipped with a mold.

The male mold 11 and female mold 12 used in such a molding method usually include a container body 2 and a lid 3.
A convex portion 11a, a concave portion 12a, and substantially flat surface portions 11b and 12b are formed at corresponding positions.

Between the convex portion 11a and the surface portion 11b of the male mold 11 and between the recess 12a and the surface portion 12b of the female mold 12 are portions where the hinge portion 4 is to be formed, and at corresponding positions, Push mold 13, receiving mold 1
4 is fixed.

In this case, the surface of the pressing die 13 facing the receiving die 14 has a bending groove 4 forming the hinge portion 4.
Corresponding to a, a projection 13a is formed with a substantially V-shaped vertical section, and on the opposite surface of the receiving mold 14, a projection 13a is also formed with a longitudinal section, which faces the projection 13a and can mesh with it when the mold is closed. V-shaped small recess 14a
is formed.

As can be seen from FIG. 8, this small recess 14a introduces a part of the foam sheet S1 that is pressed by the protrusion 13a and bulges toward the receiving mold 14 when the mold is closed, and forms the bending groove 4a. This makes it easier to form the groove into a substantially V-shaped groove, and improves the bending condition at the hinge portion 4.

<Problems to be Solved by the Invention> In the method for molding a container as described above, there are problems such as poor assembly precision between opposing male die 11 and female die 12, or push die 13 and receiver die 14, poor processing accuracy, etc. Therefore, if a positional deviation occurs between each of these, some positional deviation will also occur between the protrusion 13a and the small recess 14a.

In this case, the protrusion 13a hanging on the small recess 14a side
The pressing force applied to the foam sheet S1 supported by the receiving mold 14 is partially too strong or too weak, making it impossible to form the bending groove 4a in the desired shape. . The hinge portion 4 formed by such so-called uneven pressure cannot perform a smooth hinge function, leading to defective bending of the container.

Moreover, even if the pressing force from the protrusion 13a applied to the small recess 14a side is too strong with respect to the foamed sheet S1, excessive pressing force will be applied to the portion where the bending groove 4a is formed, and this bending groove There is a problem that the container is sheared at 4a (hinge portion).

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and it is possible to prevent molding defects of the hinge part or shearing (hinge breakage) at the hinge part during the molding process, and to prevent the hinge part from having a desired shape. It is an object of the present invention to provide a method for molding a hinge portion that can improve the yield of a predetermined molded product, and a mold suitably used in the method for molding the hinge portion.

<Means for Solving the Problems> In order to achieve the above object, the method for forming the hinge portion of the first invention involves pressure forming a foamed sheet of thermoplastic resin to form a plurality of bending grooves. In a method for molding a hinge portion, the method includes:
The foamed sheet is elastically sandwiched between a pair of molding molds and pressure molded, and the mold for molding the hinge portion of the second invention is a foamed sheet of thermoplastic resin, A mold for forming a hinge part for pressure-molding a hinge part having a plurality of bending grooves, comprising a pressing mold and a receiving mold provided opposite to each other, and either one of the pressing mold or the receiving mold. The opposing surface of the mold is formed into an uneven shape corresponding to the plurality of bending grooves, and at least one of the pressing mold and the receiving mold is supported by an elastic member that can be elastically contracted during pressure molding. It is.

<Function> According to the method for molding the hinge portion of the first invention, a foamed sheet of thermoplastic resin is elastically sandwiched between a pair of molds and pressure molded, so that the molds face each other. Even if there is a misalignment between the molds and, for example, a biased pressing force is applied to the foam sheet supported by the receiving mold, the elastic function described above will prevent this bias. A part of the pressing force can be absorbed, and the pressing force of the pressing mold on the foam sheet can be made uniform. Thereby, for example, variations in the finished shape of the bending grooves forming the hinge portion can be prevented.

Even if an excessive pressing force is applied by the pressing mold to the foam sheet supported by the receiving mold, the elastic function absorbs a portion of this excessive pressing force. I can do it.
Thereby, for example, shearing of the foam sheet at the hinge portion can be prevented.

Further, according to the mold for forming the hinge portion of the second aspect of the invention, at least one of the pressing mold and the receiving mold is supported by an elastic member that can be elastically contracted. When closed, the hinge portion molding portion of the foam sheet sandwiched between them can be elastically press-molded, and the molding required in the hinge portion molding method of the first invention can be reliably performed. .

<Examples> Examples will be described in detail below with reference to the accompanying drawings showing examples. Note that the same reference numerals will be used to describe common components of the conventional integral molding molds and the like shown in FIGS. 7 and 8.

In FIGS. 1 and 2, the mold for forming the hinge part adopts the conventionally known mold for forming the hinge part shown in FIGS. 7 and 8 above as its basic structure,
As shown in FIGS. 7 and 8, a male die 11 is used to close the heated and softened foam sheet S1 to form a packaging container 1 of a predetermined shape (see FIGS. 5 and 6). The female type 12 is equipped with this.

The molds for forming such a hinge portion are located opposite to each other, similar to conventionally known molds, and are mounted between the convex portion 11a and the flat surface portion 11b of the male mold 11. 13, and a receiving mold 14' provided between the recessed part 12a and the flat surface part 12b of the female mold 12.

Of these, the receiving mold 14' has a substantially flat surface facing the pressing mold 13, and
It is supported by an elastic member 15 that can be elastically contracted and is in contact with the back surface.

The elastic member 15 is housed in a housing hole 19 formed in the female die 12 with a slight allowance space 18 in between, and, for example, contracts in the pressing direction of the pushing die 13 and releases the pressing force. It will be restored accordingly.

As the elastic member 15, a block-shaped urethane rubber is used, but other than this, a synthetic resin material having elasticity may be used, or a metal member such as a coil spring may be used. Also good.

On the other hand, the substantially flat opposing surface 14 of the receiving mold 14'
a' is for preventing the projection 13a of the push mold 13 from meshing with the receiving mold 14' side when the mold is closed, and the projection 13a and the receiving mold 14'
This allows for some misalignment with the sides.

The molding process for manufacturing the packaging container 1 (see FIG. 5) will be described with reference to FIGS. 1 and 2.

The male mold 11 and the female mold 12 are an upper mold and a lower mold that are installed in a known pressure molding device (not shown). Concave and convex portions corresponding to the outer shape of 1 are formed. Note that the shapes of the male mold 11 and the female mold 12 have been explained in FIGS. 7 and 8, and will therefore be omitted here.

First, as shown in Fig. 1, the male mold 11 and the female mold 1
2, the heated and softened foam sheet S1 is placed between the foam sheet S1 in the softened state, and then, as shown in FIG. 2, the male mold 11 and the female mold 12 are closed.
is pressure-molded to form a packaging container 1 of a predetermined shape (see FIG. 5).

The molding process using the male mold 11 and the female mold 12 is basically carried out in the same manner as normal sheet molding, and other structures such as the sheet holding mechanism and heating mechanism are also different from conventional equipment. Since the structure is similar to that shown in FIG.

At this time, as shown in FIG. 2, between the male die 11 and the female die 12, a thermoplastic resin foam sheet S1 is elastically inserted and pressure molded. Therefore, even if, for example, a positional shift occurs between the pushing die 13 and the receiving die 14' that face each other, and a biased pressing force is applied to the foam sheet S1 supported on the receiving die 14' side, The elastic member 15 is the receiving mold 1
4' absorbs a portion of the biased pressing force applied to this receiving mold 14'. However, the degree of contraction of the elastic member 15 is such that the elastic member 15 contracts too much due to the pressing force from the pressing die 13 side.
3 is set to such an extent that it does not break through the foam sheet S1.

Thereby, it is possible to make the uneven pressing force of the pressing die 13 on the foam sheet S1 uniform, and it is possible to prevent variations in the finished shape of the bending grooves 4a due to the desired pressing force. Even if an excessive pressing force is applied by the pressing die 13 to the foam sheet S1 supported by the foam sheet S1, the elastic member 15, which also exhibits the above-mentioned good elastic function, absorbs a part of this excessive pressing force. be able to. Thereby, excessive pressing force on the foam sheet S1 can be alleviated, and unnecessary shearing of the foam sheet S1 at the hinge portion 4 can be prevented.

In this case, since the surface 14a' of the receiving mold 14' facing the pressing mold 13 is formed in a substantially flat shape, it is possible to eliminate the meshing relationship with the protrusion 13a on the receiving mold 14' side when the mold is closed. can.
As a result, it is possible to eliminate the misalignment between the push mold 13 and the receiving mold 14' due to the above-mentioned positional misalignment, etc., and to more effectively prevent shearing at the hinge portion 4. I can do it.

That is, the facing surface 14a' of the receiving mold 14' allows for some positional deviation between the protrusion 13a and the receiving mold 14', and in addition to supporting the receiving mold 14' by the elastic member 15, the opposing surface 14a' of the receiving mold 14' Type 11,
The assembly work of the female die 12, the push die 13, the receiver die 14', etc. can be facilitated, and the machining accuracy of the push die 13 and the receiver die 14' can be kept relatively rough.

When the packaging container 1 is molded in this way, the male mold 11 and the female mold 12 are opened, and the packaging container 1 is molded.
After removing from the mold, a packaging container 1 shown in FIG. 5 is obtained.

Thereafter, the packaging container 1 is transported to a trimming device or the like in a post-process and is trimmed.

Next, FIGS. 3 and 4 show modified examples of the receiving mold. The receiving mold 16 shown in FIG. 3 has a substantially T-shaped longitudinal section, and has a narrow portion 1 at the bottom of the facing surface 16a.
An extra space 18 is provided around 6b to allow deformation of the elastic member 15.

The receiving mold 17 shown in FIG.
An allowance space 18 for allowing deformation of the elastic member 15 is provided around the lower portion of the substantially trapezoidal accommodation hole 19 formed in the elastic member 15 .

In the above embodiments, the elastic member was provided on the side of the receiving mold installed in the female mold. However, in addition to this, this elastic member may also be provided on the side of the pressing mold equipped on the male mold to support the pressing mold, or at the same time to support both of them elastically. The press mold and the receiving mold used for forming the hinge part of this invention are as follows:
The present invention is not limited to the embodiments described above, and various design changes can be made without departing from the gist of the present invention.

Further, in the present invention, sheet molded products include not only the illustrated packaging container for natto, but also packaging containers for storing various foods and other products, and various conventionally used packaging containers with hinged parts. It can be freely applied to sheet molded products.

<Effects of the Invention> As described above, according to the method for forming the hinge portion having the configuration of the first invention, for example, positional deviation occurs between the molds, and the supporting mold is not supported by the mold on the receiving side. Even if an uneven pressing force is applied to the foam sheet, the foam sheet is elastically sandwiched between the sheets, so that part of the pressing force can be absorbed. The uneven pressing force can be made uniform. Thereby, for example, it is possible to prevent variations in the finished shape of the bending grooves constituting the hinge portion, and it is possible to reduce molding defects of the hinge portion during the molding process.

Even if an excessive pressing force is applied to the foam sheet supported by the receiving mold from the pushing mold, the elastic clamping function absorbs a portion of this excessive pressing force. I can do it. Thereby, it is possible to prevent the foam sheet from being sheared at the hinge portion, and it is possible to mold the hinge portion in a desired shape, and it is possible to achieve the unique effect of increasing the yield of a predetermined molded product.

Further, according to the mold for forming the hinge part of the second invention, when the pressing mold and the receiving mold are closed, the forming part of the hinge part of the foam sheet sandwiched between them is elastically press-molded. Therefore, the unique effect of being able to reliably perform the molding required in the method for molding the hinge portion of the first invention is achieved.

[Brief explanation of drawings]

1 and 2 show a male mold and a female mold, which are equipped with a hinge molding method and a molding mold according to an embodiment of the present invention, and FIG. 1 shows a cross section before mold closing. Figure 2 is a sectional view after the mold is closed, Figures 3 and 4 are sectional views showing modified examples of the mold, and Figure 5 is a sectional view showing a modified example of the mold.
The figure and FIG. 6 show a packaging container manufactured by a male mold and a female mold equipped with a hinge part molding method and a mold for molding, and FIG. 5 is a sectional view of the container in an open state;
Figure 6 is a cross-sectional view with the lid open, Figures 7 and 8 show conventional male and female molds, Figure 7 is a cross-sectional view before the mold is closed, and Figure 8 is a cross-sectional view after the mold is closed. . 1...Packaging container, 4...Hinge part, 13...
Pushing mold, 14'...Receiving die, 15...Elastic member,
S1...Foam sheet.

Claims (1)

[Claims] 1. Pressure molding a thermoplastic resin foam sheet,
A method for molding a hinge portion having a plurality of bending grooves, characterized in that the foam sheet is elastically sandwiched between a pair of molding molds and pressure molded. molding method. 2. A mold for forming a hinge part for pressure-molding a hinge part having a plurality of bending grooves on a foamed sheet of thermoplastic resin, comprising a pressing mold and a receiving mold provided opposite each other, The facing surface of either the press mold or the receiving mold is formed into an uneven shape corresponding to the plurality of bending grooves, and at least one of the pressing mold and the receiving mold is elastically contractible during pressure molding. A mold for forming a hinge portion, the mold being supported by an elastic member.