JP4516850B2 - Double-walled box-shaped blow-molded product and method for producing the same - Google Patents

Description

  The present invention relates to a double-walled box-shaped blow-molded article suitable for use in, for example, a heat retaining container for transfer, a cooler box, a simple refrigerator, a large liquid container, and the like, and a method for producing the same.

It is known to produce double-walled containers (for example, cooler boxes) by plastic blow molding, but in particular, the bottom is deep, the draft angle is small, and the double-walled thickness is thin. In this case, since the parisons (parts corresponding to the inner and outer walls of the double wall) are in contact with each other and welded in the process of clamping, 2 defective products in which the inner and outer walls of the double wall are welded randomly. There was a problem that a heavy wall container would be formed. This is the process of narrowing the parison into the female cavity by the male mold (in this case, the parison is under an internal pressure lower than the blow pressure), and the parison is strongly pulled in the length direction and broken. This is because air escapes from the tear, the internal pressure of the parison decreases, and the portion of the parison overhanging the female mold squeezes and sticks to the male mold side.
In order to improve this, the methods shown in Patent Documents 1 to 5 below have been devised, but even in these methods, the parison may be broken in the process of narrowing the parison into the cavity, and the internal pressure of the parison becomes , The part of the parison overhanging the female side is squeezed and the parison comes into contact with each other and welds.

On the other hand, when producing a heat insulating container such as a heat retaining container or a cooler box by blow molding, to increase the heat insulation of the blow molded product, as shown in Patent Document 6 below, an opening is formed at an appropriate position of the blow molded product, From there, the inside of the double wall is filled with foam beads having heat insulation properties. However, the heat insulating property of the expanded beads is not sufficient, and it is necessary to fill the interior with a large amount of expanded beads by increasing the thickness of the double wall (increasing the interval between the inner and outer walls). Only insulated containers are obtained.
Also, the double-walled container obtained by blow molding is cut and separated into the inner wall side and the outer wall side, a vacuum panel is attached to the inner wall side inner surface (five surfaces), and then the inner wall side and the outer wall side are connected again. It is also known to produce heavy-wall insulated containers. Since the vacuum panel is excellent in heat insulation, the heat insulation container manufactured by this method is excellent in heat insulation, but this method increases the number of steps and increases the cost, so that the low cost of blow molding cannot be utilized. There is. The vacuum panel is a highly heat-insulating panel whose inside is evacuated, for example, two metal plates made of aluminum, stainless steel, or the like are placed facing each other with a predetermined gap, and the surroundings are seam welded, It is produced by vacuum-sealing the inside and is known per se. A rib for preventing crushing is interposed between the two plates as needed, and the internal space is filled with a heat insulating material such as glass wool as necessary.

Japanese Patent Publication No.46-14153 JP-A-60-67130 JP-A-6-31797 Japanese Patent Laid-Open No. 7-1563 Japanese Patent Application Laid-Open No. 11-90976 Japanese Utility Model Publication No. 6-46483

  The present invention has been made in view of the problems of the prior art in the case of producing a double-walled container (box-shaped blow molded product) by plastic blow molding. The main object is to prevent the production of defective double-walled containers in which the inner and outer walls of the double wall are randomly deposited, by preventing the welding of the portion corresponding to the outer wall). Another object of the present invention is to produce a box-shaped blow-molded product with high heat insulation at low cost even if the double wall is thin.

  The double-wall box-shaped blow-molded product according to the present invention has one plate-like body on each of the bottom wall and the four peripheral walls of the integrally-formed double-wall box-shaped blow-molded product. The plate-like body in each peripheral wall is connected to the periphery of the plate-like body in the bottom wall, folded upward around the plate-like body in the bottom wall, and the plate-like body in the bottom wall is It is characterized by having a substantially closed box shape with five sides. The plate-like body is made of a material that does not weld to the parison plastic. Further, it is desirable to use a heat insulating plate such as a vacuum panel as the plate-like body.

The method for manufacturing a double-walled box-shaped blow-molded product according to the present invention is a plate that can be expanded and folded into a box shape by connecting a rectangular peripheral plate-shaped body to each side of the rectangular central plate-shaped body. The mold is placed in the parison so that the surface of the central plate is oriented almost perpendicular to the movement direction of the male and female molds. And sandwiching the plate-like object together with the parison by a female mold, folding the plate-like object into a box shape, holding the parison and the plate-like object in a cavity constituted by a male mold and a female mold, and subsequently parison Blow molding is performed by blowing pressurized air into the inside. In the produced blow molded product, the central plate-like body of the plate-like product folded in a box shape is held inside the double wall of the bottom wall, and the peripheral plate-like body is held inside the double wall of the peripheral wall. The
When the plate-like object is unfolded, each peripheral plate-like object has a gap between adjacent ones, but the gap becomes smaller in the process of folding the plate-like object into a box shape, and finally Is almost closed.

According to the method for manufacturing a double-walled box-shaped blow molded article according to the present invention, a plate-like object is arranged inside a cylindrical parison and folded into a box-like shape at the time of clamping, thereby the male side of the parison. And the female mold side (portions corresponding to the inner and outer walls of the molded product) are separated from each other, so that the parison is prevented from being welded. Therefore, a double-walled box-shaped blow molded product in which the bottom of the box-shaped blow molded product to be manufactured is deep, the draft angle is small, and the double wall is thin, preventing random welding of the inner and outer walls. Can be manufactured.
In addition, according to the manufacturing method of the present invention, part of the parison pressed by the male mold enters the gap between adjacent peripheral plate-like bodies in the process in which the mold clamping is started and the plate-like object is folded into a box shape. Since this parison forms a longitudinal rib connecting the inner wall and the outer wall at the corner of the box-shaped blow molded product, the rigidity of the box-shaped blow molded product is enhanced.

  According to the present invention, disorderly welding of the parison during blow molding is prevented, so that even a molded product having a deep bottom, a low draft, and a thin double wall can be manufactured, and a volumetric efficiency double wall box shape is obtained. A blow molded product is obtained. And it becomes a box-shaped blow-molded article excellent in heat insulation by using a heat insulation board as a plate-shaped object. In particular, when a vacuum panel is used as the heat insulating plate, a box-shaped blow-molded product having excellent heat insulating properties can be obtained even if the double wall is thin due to its excellent heat insulating properties. In order to improve the heat insulation of the box-shaped blow molded product, the plate-like bodies (heat insulating plates) held on the four peripheral walls of the box-shaped blow molded product are adjacent to each other, and It is necessary to have a height approximately equal to the height of the inner walls of the four peripheral walls.

Hereinafter, with reference to FIGS. 1-11, the double-walled box-shaped blow molded product and its manufacturing method according to the present invention will be described in detail.
1 to 6 show a manufacturing process of a double-walled box-shaped blow-molded product. FIG. 1 shows the time when the parison 2 is extruded downward from the extrusion die 1. A male device 3 and a female device 4 are arranged opposite to each other of the parison 2, and a plate-like object 5 is supported by the support member 6 below the extrusion die 1, and is located in the hollow interior of the extruded parison 2. ing.
The plate-like object 5 is formed by connecting rectangular peripheral plate-like bodies 5b to 5e to each side of a rectangular central plate-like body 5a, and is in a developed state as shown in FIG. The peripheral plate-like bodies 5b to 5e and the central plate-like body 5a can be bent at the connecting portion from a state in which there is a large gap between them to a state in which they are folded into a box shape (see FIG. 6). When the plate-like object 5 is folded into a box shape, adjacent ones of the peripheral plate-like bodies 5b to 5e are in a substantially closed state. The central plate member 5a and the peripheral plate members 5b to 5e are connected to each other with, for example, an adhesive tape without a gap.

The male mold device 3 includes a male mold 7, a support member 8, and horizontal driving means (not shown) that horizontally moves the male mold 7, and the male mold 7 has a core portion 7a that protrudes in the center. The female mold device 4 includes a female mold 9 (a central mold 11 and upper and lower molds 12 and 13) that is a divided mold, a support member 14, and a horizontal driving means (not shown) that horizontally moves them. A vertical driving means (not shown) for driving the vertical molds 12 and 13 in the inner and outer directions (vertical direction) with respect to the center thereof is provided. The central mold 11 includes a bottom wall forming portion 11a and side wall forming portions 11b and 11c. At these portions, a protruding die 15 that can be protruded into the cavity by a driving means (not shown) is installed. , 13 is formed with a protruding mold 16 protruding into the cavity.
The core portion 7a of the male mold 7 has a substantially rectangular parallelepiped shape and has an outer shape that fits inside the parison 2 when the plate-like object 5 is folded into a box shape. The female mold 9 has a predetermined cavity space between the female mold 7 and the male mold 7 (particularly the core portion 7a) when the divided upper and lower molds 10 and 11 are gathered inside and combined with the central mold 9. It is finished in the inner shape as configured.

Next, a method for manufacturing a double-walled box-shaped blow-molded product and the manufactured blow-molded product will be described in order.
(1) As shown in FIG. 1, the plate-like object 5 is installed at a predetermined position below the extrusion die 1. At this time, the surface of the central plate-like body 5a is perpendicular to the moving direction of the male mold 7 and the female mold 9, and the peripheral plate-like bodies 5b to 5e are not necessarily essential but are on the male mold 7 side. It is arranged to be in a slightly bent state.
(2) The parison 2 is extruded from the extrusion die 1, and the plate-like object 5 is located in the hollow interior of the parison 2.
(3) The mold clamping is started by horizontally moving the male mold 7 and the female mold 9 inward. At this time, the female mold 9 is in a divided state, and all the protruding molds 15 installed in the central mold 11 are retracted, and are flush with the inner surfaces of the bottom wall forming part 11a and the side wall forming parts 11b and 11c. It is in.

(4) As the mold clamping progresses, as shown in FIG. 2, the parison 2 and the plate-like object 5 are sandwiched between the male mold 7 and the female mold 9, and the plate-like object 5 is combined with the parison by the male mold 7. While being pushed into the female die 9, it is gradually folded into a box shape, while the male die 7 pushes the parison 2 into the plate-like object 5 being folded into a box shape. A part of the parison 2 pushed into the female mold 9 enters the gap between the side wall forming portions 11b and 11c of the central mold 11 and the upper and lower molds 12 and 13, and the parison 2 is pushed into the plate-like object 5. A part of enters the gap between the peripheral plate-like bodies 5 b to 5 e of the plate-like object 5.
At this time, a large tension acts on the parison 2 and the parison 2 is torn (in FIG. 2, it is torn at the exit of the extrusion die 1 and the break is indicated by an arrow S), and the internal pressure in the parison 2 is released. The disorderly welding of Parison 2 does not occur.
(5) Subsequently, as shown in FIG. 3, the upper and lower molds 12 and 13 are moved inward. In the meantime, the parison 2 and the plate-like object 5 are pushed into the female mold 9, and the plate-like object 5 is being folded into a box shape, and the male mold is placed in the plate-like object 5 being folded. The parison 2 on the 7th side is pushed, and a part of the parison 2 pushed into the female die 9 enters the gap between the side wall forming portions 11b and 11c of the central die 11 and the upper and lower dies 12 and 13, and the plate A part of the parison 2 pushed into the inside of the object 5 enters the gap between the peripheral plate members 5 b to 5 e of the plate object 5.

(6) As shown in FIG. 4, the upper and lower molds 12, 13 are brought into contact with the central mold 11 to complete the combination of the female molds 9 (clamping of the female mold 9). And the female die 9 come into contact with each other to complete the whole mold clamping. The protruding mold 15 protrudes into the cavity at an appropriate timing before and after the completion of mold clamping, and pressurized air is blown into the parison 2 to perform blow molding.
By clamping the female mold 9, the part 2 a that has entered the gap between the side wall forming portions 11 b and 11 c of the central mold 11 and the upper and lower molds 12 and 13 on the female mold 9 side of the parison 2, and the male mold The portion 2b that has entered the gap between the peripheral plate-like bodies 5b to 5e of the plate-like object 5 is pinched off together (see FIG. 7 for the portions 2a and 2b).
(7) After the blow molded product is solidified, as shown in FIG. 5, the male mold 7 and the female mold 9 are retracted, the projecting mold 15 is retracted, and the upper and lower molds 12, 13 are retracted to the outside. Further, as shown in FIG. 6, the male mold 7 and the female mold 9 are moved backward to take out the blow molded product 17 (with burr).

  As shown in FIG. 7, in the blow-molded product 17 (with burr), a parison (a side wall of the central mold 11 on the female mold 9 side) bumped on the corners on the male mold 7 side and the female mold 9 side. A portion 2a that has entered the gap between the portions 11b and 11c and the upper and lower molds 12 and 13, and a portion 2b) that has entered the gap between the peripheral plate-like bodies 5b to 5e of the plate-like object 5 on the male mold 7 side. The center mold 11 and the upper and lower molds 12 and 13 are clamped together to be removed as burrs. This also helps to reduce the weight of the blow molded product 17 (after deburring). However, in the part 2b, the corners of the plate-like object 5 (side edges of the peripheral plate-like bodies 5b to 5e) closed from the inner wall (see FIGS. 8 to 10) of the blow molded body 17 are closed. The parison existing between the part and the line P of the pinch-off remains inside the double wall as a hidden rib 25 (see FIG. 10) in the blow molded product 17. In addition, the said part 2b is pinched | interposed between the sides of the peripheral part plate-shaped bodies 5b-5e in the said corner part of the plate-shaped object 5 folded in box shape, and is thinned.

  8 to 10 show a perspective view and a cross-sectional structure of the blow molded product 17 (after deburring). The blow-molded product 17 is a box-shaped molded product composed of a bottom wall 18 and four peripheral walls 19 to 22 each consisting of a double wall (inner wall 17a, outer wall 17b), and is box-shaped inside the double wall. The plate-like object 5 folded in is held. The central plate-like body 5a of the plate-like object 5 has a contour substantially equal to the inner wall side of the bottom wall 18, and the peripheral plate-like bodies 5b to 5e have a contour substantially equal to the inner wall side of each peripheral wall 19-22. Has been.

A part of the outer wall 17b of the double wall is recessed inward, and the tips of the concave ribs 23 and 24 formed thereby are in contact with the back surfaces of the plate-like bodies 5a to 5e. The inner surface side of 5 is in contact with the inner wall 17b of the double wall, and the plate-like object 5 is held inside the double wall while being sandwiched from both sides. The ribs 23 and 24 are formed by the protruding mold 15 installed on the central mold 11 of the female mold 9 and the protruding mold 16 installed on the upper and lower molds 12 and 13, and the plate-like object 5. And the depression of the rib 24 has a function as a handle of the blow molded product 17.
Further, at each corner portion of the blow molded product 17, the hidden rib 25 described above is formed between the inner wall 17a and the outer wall 17b. This hidden rib 25 remarkably improves the rigidity of the blow molded product 17.

In the above example, the side wall forming portions 11 b and 11 c of the central mold 11 of the female mold 9 are fixed to the support member 14. However, these may be movable inward and outward in the same manner as the upper and lower molds 12. . In that case, the movement timing of the side wall forming portions 11b and 11c and the upper and lower molds 12 relative to the movement of the male mold 7 and the female mold 9 can be set as appropriate. For example, the male mold 7 and the female mold 9 are clamped. It is also possible to set the timing such that the side wall forming portions 11b and 11c and the upper and lower molds 12 are moved inward after being moved to the front, thereby folding the plate-like object 5 into a box shape. When the side wall forming portions 11b and 11c are movable inward and outward, the protruding mold 15 may be fixed to the side wall forming portions 11b and 11c similarly to the protruding mold 16 in the upper and lower molds 12 and 13.
Further, in the blow molded product 17, as described in Patent Document 6, the space between the double wall inner and outer walls 17 a and 17 b is filled with heat insulating foam beads to further improve the heat insulating property. it can.

  A blow molded article 26 shown in FIG. 11 is another example of the double wall blow molded article according to the present invention, and there is no equivalent to the concave ribs 23 and 24 in the blow molded article 17. It differs from the blow-molded product 17 in that the plate-like object 5 that is thin and held inside the double wall is sandwiched between the inner wall 26a and the outer wall 26b.

It is a typical perspective view (before the process start) for demonstrating the method of this invention. It is a typical perspective view in the middle of a process similarly. It is a typical perspective view in the middle of a process similarly. It is a typical perspective view in the middle of a process similarly. It is a typical perspective view in the middle of a process similarly. It is a typical perspective view in the middle of a process similarly. It is a typical perspective view of the blow molded product (with a burr | flash) manufactured by the method of this invention. It is a perspective view of the blow molded product after deburring similarly. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is sectional drawing of another blow molded article manufactured with the method of this invention.

Explanation of symbols

2 Parison 5 Plate 5a Central Plate 5b-5e Peripheral Plate 7 Male Die 9 Female Die

Claims (9)

One plate-like body is held in the bottom wall of the double-wall box-shaped blow-molded product formed integrally and the double wall of the four peripheral walls, and the plate-like body in each peripheral wall is a plate in the bottom wall. It is connected to the periphery of the plate-like body, is folded upward around the plate-like body in the bottom wall, and forms a substantially closed box shape of five surfaces including the plate-like body in the bottom wall. Double-wall box-shaped blow molded product. The double-walled box-shaped blow-molded product according to claim 1, wherein the plate-shaped body is in contact with the inner wall of the double-walled wall. The part of the outer wall of the double wall is recessed inward, and the tip of the concave rib formed thereby is in contact with the back surface of the plate-like body. Double-walled box-shaped blow molded product. 2. The double-wall box-shaped blow molding according to claim 1, wherein the plate-like body has a thickness substantially equal to a gap inside the double wall and is sandwiched between an inner wall and an outer wall. Goods. The double wall according to any one of claims 1 to 4, wherein a rib connected from the inner wall to the outer wall is formed in a vertical direction inside the double wall of the corner portion of the box-shaped blow molded product. Box-shaped blow molded product. The double-walled box-shaped blow-molded product according to any one of claims 1 to 5, wherein the plate-like body is a vacuum panel. A rectangular peripheral plate-like body is connected to each side of the rectangular central plate-like body so that it can be expanded and folded into a box shape. The plate is placed so that the surface is oriented substantially perpendicular to the moving direction of the clamping of the male mold and the female mold, and the plate-like object is sandwiched with the parison by the male mold and the female mold when clamping the mold. The object is folded into a box shape, and the parison and the plate-like object are held in a cavity constituted by a male mold and a female mold, and then blown by blowing pressurized air into the parison. A method for producing a double-walled box-shaped blow-molded product. When the mold is clamped, part of the parison enters between adjacent peripheral plates, and when the plate is folded into a box shape, the gap between adjacent peripheral plates closes and the parison is sandwiched A method for producing a double-walled box-shaped blow-molded product according to claim 7. A female mold has a protrusion that protrudes into the cavity, and the protrusion is in contact with the back surface of the plate-like object via a parison, and a concave shape that contacts a part of the outer wall of the double wall with the back surface of the plate-like body. The method of manufacturing a double-walled box-shaped blow-molded product according to claim 7 or 8, wherein the rib is formed.

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