JP3236655B2 - Blow-molded double-wall structure and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow blow-molded double-walled structure having one wall and the other wall facing each other, which is manufactured by blow-molding a thermoplastic resin material. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as this type of blow molded double wall structure, there is the following one.

[0003] As shown in FIG. 13, a hollow plate body formed integrally by air blowing a parison is used as a main component, and the main component is formed integrally with a left face plate 101 and a right face plate 102 therein. A fitting made of a thermoplastic resin having a required number of reinforcing plates 103 at a required position by a part of a parison (see Japanese Patent Application Laid-Open No. 58-101988).

[0004]

The above-mentioned prior art has the problems that an extremely thin portion or a broken portion is easily generated in the reinforcing plate at the time of molding, and the rigidity cannot be increased too much.

Therefore, if the thickness of the reinforcing plate is increased in order to increase the rigidity, shrinkage after molding causes sink marks and warpage on the outer surfaces of the left and right double-sided plates where the reinforcing plates are joined. And the appearance becomes worse.

In order to avoid this, as shown in FIG. 14, it is conceivable to increase the rigidity by reducing the space between the reinforcing plates 203A and 203B adjacent to each other. Occasionally, there is a problem in that the parison does not expand well, and the mold structure is complicated and the mold cost is high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to increase mechanical strength such as stiffness, and to provide a blown blow having a good appearance without sinking or warping on the outer surface. It is an object of the present invention to realize a molded double-walled structure and a method of manufacturing the same.

[0008]

In order to achieve the above object, a blow-molded double-walled structure according to the present invention is provided with one wall facing each other manufactured by blow-molding a thermoplastic resin material. A hollow double-walled structure having the other wall, wherein an outer wall is provided between the one wall and the other wall.
A plate-like rib is integrally formed so as not to be seen from the side, and a void portion is formed inside a vicinity of a welded portion of the rib with the one wall. Things.

The method for producing a blow-molded double-walled structure of the present invention comprises the steps of: forming a hollow double-walled structure having one wall and the other wall facing each other by blow-molding a thermoplastic resin material. a method of manufacturing a wall structure, the Parisun melted between mold open and mold was closed later type extruded, then part whereas <br/> of the portion is the other of the walls of the Parisun wherein by projecting deformed toward the portion to be a wall
After forming a gap in the vicinity of the welded portion and the welded portion by abutting on a portion to be one wall, a pressurized fluid is introduced into the parison and expanded to form a mold cavity at the same time. , it is characterized in that formed invisibly to a plate-like rib having a gap portion inside the welded portion near the welded integrated so the one with the wall open side of the gap from the outside.

[0010]

[Function] By forming a gap inside the vicinity of the welded portion of the plate-shaped rib with one wall, the strength of the plate-shaped rib is increased as if the thickness of the plate-shaped rib were increased, and the rigidity and other mechanical properties were increased. The target strength is increased, and sink and warpage do not occur on the outer surface of one of the walls where the plate-like ribs are joined at the time of molding.

The blow-molded double-walled structure of the present invention is required to have mechanical strength such as rigidity, such as housing panels for electric equipment and furniture, automobile parts such as rear shelves and console boxes, carrying cases and containers. Suitable for containers such as.

[0012]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional perspective view of a main part of a blow-molded double-wall structure according to a first embodiment, and FIG. 2 is a plan view thereof.

This embodiment has one wall 1 and the other wall 2 facing each other manufactured by blow molding a thermoplastic resin material, and the entire peripheral surface thereof is closed by an end wall 6. a hollow double-walled structure that is, one of the walls 1 and two plate-like ribs 3 mutually spaced between the other wall 2 outer
From the are formed integrally with each wall 1 to be invisible, respectively in the interior of the one welded portion near the wall 1 of the gap portion 4 of each rib 3 is formed. In addition, the gap 4
Are closed by a solid portion 3A.
The other portions are hollow portions 5.

One wall 1, the other wall 2, the end wall 6, and the plate
The ribs 3 are formed integrally from one parison in one molding cycle as described later, and the outer shape of the ribs 3 is one It is formed in a tapered shape from the wall 1 toward the other wall 2. For this reason, the strength is increased as if the thickness of the rib was thick, and the mechanical strength such as rigidity is improved.

In addition, the influence of shrinkage during molding does not appear on the outer surface of the portion of the wall 1 where the ribs 3 are welded, and the appearance is good.

Next, a second embodiment shown in FIG. 3 will be described.

FIG. 3 is a partially cutaway perspective view of the blow molded double wall structure of the second embodiment.

In this embodiment, as shown in FIG.
Are substantially circular in cross section, and therefore the ribs 13
Is formed of a protruding portion that protrudes in an arc shape at the space 14 and a plate-shaped solid portion that joins the protruding portion and the other wall 2. In addition, both ends of the void portion 14 are closed by the solid portion 13A, and portions other than the respective ribs 13 are hollow portions 15. Otherwise, the configuration is the same as in the first embodiment, and a description thereof will be omitted.

In each of the above embodiments, two ribs are provided. However, it is needless to say that the number of ribs can be one or three or more as necessary.

FIG. 4 shows an example in which the blow molded double wall structure according to the present invention is applied to a housing panel C ₁ of a copying machine C. This housing panel C ₁ has a curved corner portion C ₂
Have, but opposing walls is a component of two-dimensionally or three-dimensionally altered three-dimensional shape, according to the present invention, each wall also uniform wall thickness of such a curved corner portion C ₂ It can be.

Here, an embodiment of the method of manufacturing the blow molded double wall structure of the present invention will be described.

First, a method of manufacturing the blow-molded double wall structure of the first embodiment shown in FIGS. 1 and 2 will be described with reference to FIGS.

As shown in FIG. 5, the opened mold 8A,
After extruding the melted parison 7 from the extrusion head of an extruder (not shown) during 8B, the mold is closed.

Next, by projecting a plate-shaped slide portion 9 slidably disposed on the other mold 8B toward the parison 7, a part of the other wall portion of the parison 7 is formed on one side. The welded portion is formed by projecting and deforming toward the wall portion so as to abut on one wall portion. At this time, a gap is formed near the welded portion by the tip of the slide portion 9.

After that, when the slide part is retracted to the position shown in FIG. 7, the parison 7 is deformed by its internal pressure, and the rib 3 on the open side is left in a state where a gap is left near the welded part.
Approximately the central portion of the portion to be contacted is welded.

As described above, welding is performed by contacting the open side with the gap left in the vicinity of the welded portion because of the relative relationship between the internal pressure of the gap and the internal pressure of the paris. This is achieved by appropriately adjusting the moving speed and timing.

Next, a pressurized fluid such as air is introduced into the paris 7 by piercing the paris 7 with a blowing needle (not shown) to expand the paris 7, thereby forming the paris 7 into the shape of a mold cavity. 1, the other wall 2 and end wall 6
And welding of the rib 3 to one wall 1
By integrating welded to other parts, leaving a space portion 4 inside parts near tapered plate-like rib 3 Ri tapered over outer shape from one wall 1 to the other wall 2
Are formed so as not to be seen from the outside .

Next, a method of manufacturing the blow molded double wall structure of the second embodiment shown in FIG. 3 will be described with reference to FIGS.

As shown in FIG. 9, the opened mold 18A,
The melted parison 17 is extruded from an extrusion head 20 of an extruder (not shown) between 18B and its open end is closed.

Next, as shown in FIG. 10, the mold is closed, and the slide part 19 provided with a plurality of introduction holes 19A slidably disposed in the other mold 18B is spaced apart from each other by a parison. By projecting toward the part 17, a part of the part to be the other wall of the paris 17 is protruded and deformed and welded to the part to be the one wall of the paris 7 to form a welded part.

Thereafter, the slide portion 19 is retracted, and a pressurized fluid such as air is introduced from each of the introduction holes 19A to form a space having a substantially circular cross section, and then the slide portion 19 is moved to the position shown in FIG. Withdraw.

Then, a blow pin (not shown) is inserted into the parison 17 to introduce a pressurized fluid such as air into the parison 17 and expand the parison 17, thereby forming the parison 17 into the shape of a mold cavity and, at the same time, forming the rib 13 by integrating welded to other parts in a state where one section to the inner section of the welded portion near the wall 11 of the leaves a substantially circular gap portion 15, the outer shape is the vicinity of one of the wall 1 circle of The remaining portion forms a solid plate-like rib 13 projecting in an arc shape.

[0034]

Since the present invention is configured as described above, the following effects can be obtained.

In the vicinity of the welded portion between the plate-shaped rib and one wall .
Since a void is formed in the section, the strength is increased as if the thickness of the rib was increased, the mechanical strength such as rigidity was increased, and the fusion with the plate-shaped rib on one wall was achieved.
The appearance is good without sink marks and warpage occurring on the outer surface of the attachment portion.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a main part of a blow-molded double-wall structure according to a first embodiment of the present invention.

FIG. 2 is a plan view of the first embodiment shown in FIG.

FIG. 3 is a partially cutaway perspective view of a blow molded double wall structure according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a copying machine in which the blow molding double wall structure according to the present invention is applied to a housing panel.

FIG. 5 is a main step of the method for manufacturing the blow-molded double-walled structure of the first embodiment shown in FIGS. 1 and 2, showing a state in which a parison is extruded between the opened molds. It is sectional drawing.

6 is a fragmentary cross-sectional view showing a step of forming a welded portion by projecting the slide portion and projecting and deforming a part of the parison after the process shown in FIG. 5;

7 is a fragmentary cross-sectional view showing, after the step shown in FIG. 6, a step of forming a gap in a portion to be a rib by retracting the slide portion.

FIG. 8 is a cross-sectional view of a main part showing a step of forming a rib having a cavity at the same time as expanding the parison into a mold cavity shape, following the step shown in FIG. 7;

FIG. 9 is a schematic front view showing one step of the method of manufacturing the blow-molded double-walled structure of the second embodiment shown in FIG. 3, in which a parison is extruded between the opened molds. .

10 is a fragmentary cross-sectional view showing a step of forming a welded portion by projecting the slide portion and projecting and deforming a part of the parison after the process shown in FIG. 9;

11 is a fragmentary cross-sectional view showing, after the step shown in FIG. 10, a step of forming a gap in a portion to be a rib while the slide portion is being retracted.

12 is a fragmentary cross-sectional view showing a step of forming a rib having a cavity at the same time as expanding the parison into a mold cavity shape, following the step shown in FIG. 11;

FIG. 13 is a sectional perspective view of a main part of a conventional example.

FIG. 14 is a cross-sectional perspective view of a main part showing a modification of the conventional example shown in FIG.

[Description of Signs] 1,11 One wall 2,12 The other wall 3,13 Rib 3A, 13A Solid part 4,14 Void part 5 Hollow part 6,16 End wall 7,17 Parisin 8A, 8B, 18A, 18B Mold 9,19 Slide part 19A Inlet hole 20 Extrusion head

Claims (2)

(57) [Claims] 1. A hollow double-walled structure having a one wall and the other wall a thermoplastic resin material which mutually opposed manufactured by blow molding, the said one wall other between the wall, visible from the outside
Plate-shaped ribs are integrally formed so as not to be formed, and a void portion is formed in the vicinity of a welded portion of the rib with the one wall, and a double wall structure made by blow molding, body. 2. A method for producing a hollow double-walled structure having one wall and the other wall facing each other by blow molding a thermoplastic resin material, comprising: the molten Parisun and closed later type extruded between, then, the portion serving as the one wall by protruding deformed toward a part of the portion to be the other wall of the Parisun to one wall portion serving After forming a gap in the vicinity of the welded portion and the welded portion by abutting, a pressurized fluid is introduced into the parision and expanded to form a mold cavity, and at the same time, the open side of the gap is opened. by integrally welded of welding the vicinity of said one wall
So as not to obscure the plate-shaped rib having a gap portion from the outside part
A method for producing a blow-molded double-walled structure, characterized in that the structure is formed as follows.