JP2005041554A - Lunch box forming method, lunch box and die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lunch box which is obtained by injection-molding of synthetic resin so that a plurality of recesses to store food and outer peripheral edge frames are beautifully colored in different colors from other parts. <P>SOLUTION: A forming method to form a synthetic resin-made lunch box 11 having a plurality of recesses 12, an annular edge frame 13 of a peripheral edge, and an upper connection surface 14 to connect these components comprises a primary forming step of forming the recesses 12 and the edge frame 13 by a top surface die 16 to form a top surface of the lunch box 11 and a first bottom surface die 17, and a secondary forming step of forming a bottom surface 15 of the lunch box 11 the top surface die 16 and a second bottom surface die 18. An undercut forming part 16d to form an undercut part 13a on the edge frame 13 is provided on an inner peripheral surface at an edge frame forming part 16c of the top die 16 to prevent the edge frame 13 from being raised. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lunch box that is used repeatedly, for example, for use in catered lunches or the provision of set meals at restaurants, and more particularly to a lunch box made of synthetic resins of a plurality of colors.

  As a two-color molded lunch container, there is one formed using one upper surface mold and two lower surface molds having substantially the same cavity (Patent Document 1).

  In this method, a first molded product having a plurality of recesses for containing food is formed by an upper surface mold and a first lower surface mold, and cooled and contracted after molding. Then, instead of the first lower surface mold, the second lower surface mold is used, and the second synthetic resin having a color different from that of the first synthetic resin forming the first molded product is injected, Molding is performed on the first molded product, and the second synthetic resin is exposed at a necessary portion.

However, since the injection of the second synthetic resin is performed in the gap formed by the shrinkage of the first molded product, a very thin second synthetic resin layer of only about 0.1 mm can be formed.
For this reason, even if the two-color molding is performed, the first molded product can be seen through, and there is a difficulty in making a cheap impression.

On the other hand, the above-mentioned problems can be solved with a lunch box as in Patent Document 2.
That is, of the two lower surface molds, a mold in which the cavity of the second lower surface mold is formed larger than the cavity of the first lower surface mold is used. Therefore, the thickness of the portion molded using the second lower surface mold is reduced. Since the thickness can be made equal to the thickness of the portion molded using the first lower surface mold, a transparent appearance can be obtained. In addition, since a plurality of independent first molded products are obtained for each of the recesses of the lunch box, and the molding for integrating these molded products is performed from there, the boundary portion is also clearly visible Can be formed. For this reason, the appearance with a high-class feeling like arranging a plurality of containers (recesses) can be obtained.

  However, in addition to the recess, when the outer peripheral edge is formed in a different color to further improve the appearance, if the edge is formed independently in the same manner as the recess, the edge Since the portion is annular, there is a difficulty that it floats from the upper surface mold due to shrinkage after molding.

  If it floats, when molding using the second bottom mold, the synthetic resin of different colors enters the gap, and the synthetic resins of different colors are mixed with each other, and clean molding cannot be performed. On the other hand, the appearance will be deteriorated.

JP-A-5-162171.

JP-A-11-235777.

The main object of the present invention is to enable molding in which the edge portion has a different color in a state of being clearly color-coded.
Another object is to enable the molding as described above to be performed at a lower cost.

  Means for solving the above-mentioned problems include injection molding of a lunch box made of synthetic resin having a plurality of recesses for containing food, an annular edge frame on the outer peripheral edge, and a connecting surface on the upper surface side connecting them. A first molding step using an upper surface mold for molding the upper side surface of the lunch box, and a first lower surface mold for independently molding the recess and the edge frame, and the upper surface. A second molding of the entire lower surface including the connecting surface with the recess and the edge frame attached to the upper surface mold so as to integrate the mold and the recess and the edge frame formed in the first molding step. A second molding step using a lower surface mold, and an inner cut surface forming an undercut portion on the edge frame is provided on the inner peripheral surface of the edge frame forming portion of the upper surface mold to perform the first molding. Molding of a lunch box that prevents the edge frame from lifting after the process and before the secondary formation Characterized in that it is a law.

  That is, even if the edge frame formed by the primary molding process shrinks after molding, the undercut portion forming portion prevents the float from rising, and the position on the upper surface mold can be secured. For this reason, even if a synthetic resin having a different color is placed in the subsequent molding in the second molding step, the color can be clearly classified.

  Moreover, the edge frame can be formed in a different color in addition to the recesses in the two steps of the primary molding step and the secondary molding step.

  In addition, while setting the color of the synthetic resin used in the first molding step to one color or a plurality of colors, the color of the synthetic resin used in the first molding step is the color of the synthetic resin used in the second molding step. It is good to be different.

  Another means is a lunch box manufactured by the above method for forming a lunch box.

  Another means includes an upper surface mold for molding the upper surface side of the lunch box having a plurality of recesses for containing food, an annular edge frame on the outer peripheral edge, and an upper surface side connecting surface for connecting these, and the upper surface A first lower surface mold for forming the recess and the edge frame paired with the mold, and a concave portion and an edge frame formed by the upper surface mold and the first lower surface mold, and used instead of the first lower surface mold. And an undercut portion for forming an undercut portion on the molded edge frame on the inner peripheral surface of the edge frame forming portion of the upper surface mold. It is a metal mold for forming a lunch box provided with a forming part.

  The undercut forming portion may be formed with an inclined surface.

  Moreover, it is good to form many protrusions which melt | dissolve at the time of shaping | molding using the said 2nd lower surface type | mold on the lower surface of the edge frame formation site | part in the said 1st lower surface type | mold.

  As described above, according to the present invention, the first molding process using the upper surface mold and the first lower surface mold and the second molding process using the upper surface mold and the second lower surface mold are performed twice. A colored lunch box is obtained. In addition, since the edge frame is formed independently with the plurality of recesses in the first molding step, the edge frame can also be formed in a different color.

  In the primary molding step, the inner peripheral surface of the edge frame forming portion of the upper surface mold is provided with an undercut portion forming portion for forming an undercut portion on the edge frame. Even if the frame contracts, it can be prevented from easily coming off from the upper surface mold or floating. In other words, the edge frame can be kept firmly attached. For this reason, even if different colored synthetic resins are injected in the subsequent secondary molding step, the different colored synthetic resins do not mix with each other, and clean color coding can be realized.

  In addition, as described above, the edge frame can be formed in different colors by two moldings using the first lower surface mold and the second lower surface mold, and there is no need to use another lower surface mold for forming the edge frame. Therefore, man-hours for manufacturing can be reduced, and both labor and time can be reduced. In addition, since the mold cost is low, the cost can be reduced and the price of the product can be reduced.

  In the lunch box obtained as described above, the plurality of recesses and the edge frame are different from the upper side connection surface and the lower side surface. Appearance that surrounds is obtained. In other words, an appearance that consists of a plurality of members is obtained even though it is a single member, and as a lunch container, a special impression such as a lacquered vessel can be given, and the taste of the lunch box is increased. it can.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a lunch box 11. The lunch box 11 has six recesses 12 of different sizes and shapes so that food such as rice and side dishes can be stored separately. ing.

  The lunch box 11 is made of a synthetic resin, particularly polypropylene, and is formed of a synthetic resin of two colors such as red and black so that a high-class feeling can be obtained without painting. Color coding in red and black gives the impression of a lacquered tableware. In the lunch box in the form of the illustrated example, the recesses 12 and the annular edge frame 13 protruding upward at the outer peripheral edge are set to a first color such as red, and the recesses 12 and the edge frame 13 are formed. The connecting surface 14 on the upper surface side to be connected and the lower surface 15 of the lunch box 11 are set to a second color such as black.

  In manufacturing such a two-color lunch box 11, the first color portion (the recess 12 and the edge frame 13) is first formed, and then the second color portion (the connecting surface 14 and the lower side surface 15) is formed. Thus, both are integrated into a lunch box 11 shape. FIG. 2 is a sectional view of the lunch box 11.

  For manufacturing, three molds that are two types of combinations as shown in FIGS. 3 and 4 are used. The mold shown in FIG. 3 includes an upper surface mold 16 that molds the upper side surface of the lunch box 11, and a first lower surface mold 17 that forms the recess 12 and the edge frame 13 independently of each other in combination with the upper surface mold 16. 4, the mold shown in FIG. 4 is in the state where the recess 12 and the edge frame 13 are attached to the upper surface mold 16 so that the upper surface mold 16 and the recess 12 and the edge frame 13 are integrated. It consists of the 2nd lower surface type | mold 18 which shape | molds the whole lower surface 15 including the connection surface 14. FIG. That is, the upper surface mold 16 is common.

  In other words, the first color portion is molded by the upper surface mold 16 and the first lower surface mold 17 (first molding process). Subsequently, the second lower surface mold 18 is used in place of the first lower surface mold 17, and the second color portion is molded (secondary molding process), whereby the lunch box 11 is completed.

Here, the shape of each mold will be described.
The upper surface mold 16 is discontinuously provided with a plurality of recess forming cores 16a corresponding to the inner surface of the recess 12 formed in the lunch box 11, and is formed in the lunch box 11 on the outer peripheral side surrounding these. A groove-shaped edge frame forming core 16c having a shape corresponding to the outer peripheral surface of the edge frame 13 is formed via the connecting surface forming core 16b.

  And the undercut part formation part 16d which forms the undercut part 13a in the edge frame 13 to shape | mold is provided in the internal peripheral surface in this edge frame formation core 16c (refer FIG. 5). The undercut portion forming portion 16d is formed with a gently inclined surface having an inversely tapered shape. The inclination may be an angle smaller than 5 degrees, and more preferably around 3 degrees.

  By forming the undercut portion forming portion 16d as described above, when the edge frame 13 is formed in the first forming step, the edge frame 13 does not lift from the upper surface mold 16 even if shrinkage occurs after the forming. Can be molded clearly. Moreover, since the undercut part formation part 16d is formed in the inclined surface, if it is soft after a shaping | molding, it can be easily removed from an upper surface type | mold.

  The first lower surface mold 17 covers the recess forming core 16a when combined with the upper surface mold 16, and forms a gap with a predetermined thickness between the recess forming core 16a and the upper surface mold. A predetermined gap is formed between the abutting surface 17b that does not overlap with the connecting surface forming core 16b of the sixteen and forms the gap and the edge frame forming core 16c of the top die 16 and the edge frame forming core 16c. An edge frame forming cavity 17c.

  Holes 17d are formed on the lower surface of the edge frame forming cavity 17c so as to form a large number of protrusions 13b on the lower surface of the edge frame 13 at predetermined intervals (see FIG. 6). By providing such a hole portion 17d, a large number of projections 13d can be formed, and these projections 13d are melted by the heat of the second color synthetic resin in the second molding step. Unity can be increased. In addition to the cylindrical shape as illustrated, the protrusion 13b may have other shapes as long as the projections and depressions can be formed.

  The second lower surface mold 18 includes a lower surface forming first cavity 18a that forms a gap with a predetermined thickness on the recess 12 formed on the recess forming core 16a of the upper surface mold 16 by the first lower surface mold 17. The lower surface forming second cavity 18b that covers the connecting surface forming core 16b of the upper surface mold 16 with a gap of a predetermined thickness to form the lower surface of the corresponding portion of the connecting surface 14, and the edge frame forming core 16c of the upper surface mold 16 It has a lower surface forming third cavity 18c that forms a gap with a predetermined thickness on the edge frame 13 formed thereon.

  The gap having the predetermined thickness is a gap having a thickness capable of positively injecting the synthetic resin, and is not a thin gap that is formed by shrinkage after molding.

  Specifically, first, the upper surface mold 16 and the first lower surface mold 17 shown in FIG. 3 are used to injection-mold the first color synthetic resin, and as shown in FIG. 13 are molded independently (primary molding step). Then, instead of the first lower surface mold 16 after these molded products have dropped to a predetermined temperature, the second lower surface mold 18 is used as shown in FIG. A second color synthetic resin is injected from above (secondary forming step, see FIG. 9).

  Then, as shown in FIG. 10, the second synthetic resin covers the molded product of the first color, and the connecting surface 14 that connects the molded product of the first color, that is, the recess 12 and the edge frame 13. Is formed, and the lunch box 11 is completed.

  The predetermined temperature when the process proceeds to the second molding step is about 130 to 90 ° C, more preferably about 110 ° C when the synthetic resin is polypropylene and the injection temperature is 200 ° C. This is because the adhesion between the synthetic resins is good.

  Further, the bonding property between the synthetic resins is further enhanced by a large number of protrusions 13 d formed on the lower surface of the edge frame 13.

  The bento container 11 manufactured in this way is different in color from the recess 12 and the edge frame 13 and other parts, so that it cannot be obtained by coloring after molding or by applying a colored film. A feeling is obtained.

  Moreover, in the case of coloring or film deposition, there are problems such as peeling and food pigment deposition, but the lunch box 11 without such inconvenience is obtained.

  In addition, the upper surface mold is used in two processes, and not only the recess 12 but also the molding up to the edge frame 13 is performed in two processes using the two lower surface molds 17, 18. The cost can be reduced.

  Furthermore, since the undercut portion forming portion 16d is provided in the upper surface mold 16 so that the edge frame 13 formed in the first forming step does not float up, the lunch container 11 with a clear boundary and a beautiful appearance can be obtained reliably. It is done.

  Moreover, since the plurality of recesses 12 and the edge frame 13 are different from the connection surface 14 and the lower side surface 15 of the upper side, the lunch box 11 has an appearance in which a plurality of containers are arranged and enclosed. It is done. In other words, even though it is a lunch box made up of a single member, it has the appearance of being made up of multiple containers. Can be increased.

  The lunch box 11 in the illustrated example has a shape in which the upper end edge of each recess 12 has an upwardly protruding ridge 12a (see FIG. 1) having a substantially semicircular cross section, as shown in FIG. Moreover, it may be in a form without such ridges. In this case, the upper end portion of the outer surface of the recess 12 raised obliquely is vertically cut to form the vertical surface 12b. By forming the vertical surface 12b in this manner, the second color synthetic resin smoothly enters the upper side of the upper end of the recess 12 even when molding is performed with the same upper surface mold 16.

  Further, in the first molding step, the color of the synthetic resin forming each recess 12 and the edge frame 13 can be set to a different color because each part is formed independently.

The upper surface type edge frame forming portion in this invention corresponds to the edge frame forming core 16c in the above configuration,
The edge frame forming portion in the first lower surface mold corresponds to the edge frame forming cavity 17c.
The present invention is not limited to the above configuration.

The perspective view of a lunch container. Sectional drawing of a lunch container. Sectional drawing of an upper surface type | mold and a 1st lower surface type | mold. Sectional drawing of an upper surface type | mold and a 2nd lower surface type | mold. Sectional drawing of the principal part. The partially expanded perspective view of a 1st lower surface type | mold. Explanatory drawing of a primary shaping | molding process. Explanatory drawing which shows the transfer process from a primary shaping | molding process to a secondary shaping | molding process. Explanatory drawing of a secondary shaping | molding process. Explanatory drawing which shows a molding completion state. Sectional drawing of the lunch container from which a form differs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Lunch container 12 ... Recess 13 ... Edge frame 13a ... Undercut part 13b ... Protrusion 14 ... Connection surface 15 ... Lower side surface 16 ... Upper surface type 16c ... Edge frame formation core 16d ... Undercut part formation part 17 ... 1st lower surface Mold 17c ... Edge frame forming cavity 17d ... Hole 18 ... Second bottom mold

Claims (6)

A molding method for molding a lunch box made of synthetic resin having a plurality of recesses for containing food, an annular edge frame on the outer peripheral edge, and a connection surface on the upper surface side connecting these by injection molding,
A primary molding step by an upper surface mold for molding the upper side surface of the lunch box and a first lower surface mold for independently molding the recess and the edge frame;
In addition, the entire lower surface including the connecting surface is formed with the recess and the edge frame attached to the upper surface mold so that the upper surface mold and the recess and the edge frame formed in the first molding step are integrated. A second molding step with a second bottom surface mold,
On the inner peripheral surface of the edge frame forming portion of the upper surface mold, an undercut portion forming portion for forming an undercut portion is provided on the edge frame, so that the edge frame is lifted after the first forming step and before the second forming. How to prevent bent box containers from forming. The color of the synthetic resin used in the first molding step is set to one color or a plurality of colors, and the color of the synthetic resin used in the second molding step is different from the color of the synthetic resin used in the first molding step. The method for forming a lunch box according to claim 1. A lunch box manufactured by the method for molding a lunch box according to claim 1 or 2. An upper surface mold for molding the upper surface side of the lunch box having a plurality of recesses for containing food, an annular edge frame of the outer peripheral edge, and a connection surface on the upper surface side connecting these;
A first lower surface mold for forming the recess and the edge frame in a pair with the upper surface mold;
From above the recess and edge frame formed by the upper surface mold and the first lower surface mold, there is a second lower surface mold that is used in place of the first lower surface mold and forms the entire lower surface side including the connecting surface. ,
A mold for forming a lunch box container, wherein an undercut part forming part for forming an undercut part is formed on an inner peripheral surface of an edge frame forming part in the upper surface mold. The mold for forming a lunch box according to claim 4, wherein the undercut forming portion is formed of an inclined surface. 6. A mold for forming a lunch box according to claim 4 or 5, wherein a plurality of protrusions that melt at the time of molding using the second lower surface mold are formed on the lower surface of the edge frame forming portion of the first lower surface mold.

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