JP2009132111A - Hollow double-walled structure and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow double-walled structure having a high bending rigidity, in which no distance is formed between a longitudinal inner rib and a transverse inner rib, and the longitudinal inner rib and the transverse inner rib are integrated as a series, and its manufacturing method. <P>SOLUTION: The hollow double-walled structure A has a constitution that a first wall 21 and a second wall 22 made of a thermoplastic resin come between, and is characterized by a rib structure in which the longitudinal inner rib 11, the transverse inner rib 12 going straight to the longitudinal inner rib 11, and a cross-shaped crossover part 13 are formed in a space V formed between the first wall 21 and the second wall 22, the longitudinal inner rib 11 is combined with the transverse inner rib 12 through the crossover part 13, and at the same time, an empty part H is formed in the vicinity of the joint of the crossover part 13 with the first wall 21. Further, the manufacturing method of the hollow double-walled structure A comprises the process of closing a split mold 3, the process of fusion-bonding a parison P, the process of setting back a slide core, and the process of introducing a pressurized fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hollow double wall structure made of a thermoplastic resin and a method for producing the same.

Currently, there is a panel made of synthetic resin as a lightweight and inexpensive plate-like member.
This panel is highly versatile and is used in various situations.
For example, it is used as a material for washstands or bathroom shelves by utilizing its high corrosion resistance, and it is used for interior panels for vehicles by taking advantage of its light weight.
In addition, in order to increase the rigidity of the panel from a structural aspect, a panel with inner ribs in which reinforcing plates (so-called inner ribs) are formed in a lattice shape in the space between the front plate and the rear plate constituting the panel is also available. It has been developed (see Patent Document 1).
JP-A-56-120319 Japanese Patent Laid-Open No. 57-118965 JP-A-10-16079

  By the way, when the above-mentioned panel with inner ribs is formed by blow molding, an inner rib formed in the longitudinal direction (hereinafter referred to as “vertical inner rib”) and an inner rib formed in a direction perpendicular to the vertical inner rib ( (Hereinafter referred to as “lateral inner ribs”) formed in a cross shape, the parison is excessively stretched and thinned at the intersection, causing the parison to be broken or conversely reduced in rigidity. This obstructs the flow of blown air and causes molding defects (see FIG. 6 of Patent Document 1).

For this reason, it is conceivable that the vertical inner rib and the horizontal inner rib are not connected to each other and are formed at a predetermined interval at the intersection (see FIG. 4 of Patent Document 2).
However, when the interval is provided without connecting the vertical inner rib and the horizontal inner rib, the rigidity in the bending direction becomes insufficient, and the reinforcing effect by the inner rib cannot be obtained sufficiently.

  For this reason, the intersecting portion is formed without using a slide mold to form a concave rib (mounting hole), but it has not been solved that the base of the concave rib is stretched to become thin. In addition, since the flow of the blown air (pressurized fluid) is hindered at the intersection, it becomes a cause of molding failure, and when a plurality of intersections are provided, the molding itself becomes difficult (see FIG. 3 of Patent Document 3). reference).

The present invention has been developed to solve the above problems.
That is, a hollow double-wall structure having high bending rigidity in which no gap is formed between the vertical inner rib and the horizontal inner rib, and the vertical inner rib and the horizontal inner rib are integrated in series, and the An object is to provide a manufacturing method.

  As a result of intensive studies based on the background of the problems as described above, the present inventor has connected the longitudinal inner rib and the lateral inner rib at the intersection, and formed a void near the intersection. The present inventors have found that the above problems can be solved, and have completed the present invention based on the knowledge.

  That is, the present invention is (1) a hollow double wall structure in which a first wall and a second wall made of a thermoplastic resin are separated from each other, and is formed between the first wall and the second wall. A vertical inner rib, a horizontal inner rib that runs in a direction perpendicular to the vertical inner rib, and a cross-shaped intersection are formed in the space, and the vertical inner rib is coupled to the horizontal inner rib through the intersection. And a hollow double-wall structure having a rib structure in which a void is formed in the vicinity of the junction between the intersection and the first wall.

  In the present invention, (2), the distance between the first wall and the second wall is 25 mm or less, and the first inner wall and the second inner rib are extended to the second wall. It exists in the hollow double wall structure of said (1) description formed by the abutting fusion.

  According to the present invention, (3), the distance between the first wall and the second wall is greater than 25 mm, and the vertical inner rib and the horizontal inner rib are extended with the extended first wall. In the hollow double-wall structure according to the above (1), the two walls are formed by abutting and fusing at substantially the middle position of the space.

  Moreover, this invention exists in the hollow double wall structure of the said (2) or (3) description whose said cross | intersection part is solid (4).

  Moreover, this invention is a manufacturing method of the hollow double wall structure using the split mold which consists of (5), a 1st metal mold | die, and a 2nd metal mold, Comprising: The said 1st metal mold | die extends a parison. The slide core includes a vertical slide core that forms a vertical inner rib, a horizontal slide core that is arranged in a direction perpendicular to the vertical slide core, and a vertical slide core and a horizontal slide core that are spaced apart from each other. A thermoplastic resin parison in a molten state is disposed between the divided molds, the parison is disposed, and then the divided molds are closed; and the first mold After extending the wall surface of one parison by the slide core protruding from the cavity surface and abutting and fusing with the wall surface of the opposite parison, and fusing a part of the parison wall surface, A method for producing a hollow double-wall structure comprising: a step of pulling out an id core from a parison and retracting to a cavity surface of a mold; and a step of retracting a slide core and introducing a pressurized fluid into the parison. Exist.

  Moreover, this invention exists in the manufacturing method of the hollow double wall structure of the said (5) description used when manufacturing the hollow double wall structure whose thickness is 25 mm or less (6).

  Moreover, this invention is (7), Before closing a division | segmentation metal mold | die, by arranging a skin material between said 2nd metal mold | die and a parison, the back surface of a skin material is stuck on the wall surface of a parison integrally. It exists in the manufacturing method of the hollow double wall structure of the said (5) description.

  The present invention also relates to (8) a method for producing a hollow double wall structure using a split mold comprising a first mold and a second mold, wherein the first mold and the second mold Comprises a slide core for extending the parison, the slide core forming a vertical inner rib, a horizontal slide core arranged in a direction perpendicular to the vertical slide core, a vertical slide core, and a horizontal slide core And a cross slide core arranged at intervals, placing a parison of a thermoplastic resin in a molten state between the divided molds, placing the parison, and then closing the divided molds; The slide core protrudes from the cavity surface of the first mold and the second mold, and is pulled inward by the wall surface of the parison extended inward by the slide core of the first mold and the slide core of the second mold. A process of abutting and fusing the stretched parison wall; a process of fusing part of the parison wall and then pulling out both slide cores from the parison to the cavity surface of the mold; and slide core And a step of introducing a pressurized fluid into the parison after retreating, a method for producing a hollow double-walled structure.

  Moreover, this invention exists in the manufacturing method of the hollow double wall structure of the said (8) description used when manufacturing the hollow double wall structure (9) whose thickness exceeds 25 mm.

  The present invention also resides in (10) the method for producing a hollow double wall structure according to the above (5) or (8), wherein vacuum suction is performed from a gap between the slide core and the mold cavity.

  In addition, as long as the objective of this invention is met, the structure which combined said invention suitably is also employable.

The inner rib formed in the hollow double-wall structure of the present invention includes a vertical inner rib formed in one direction of the structure, a horizontal inner rib formed perpendicular to the vertical inner rib, and a vertical rib. And a cross-shaped intersection formed at a location corresponding to the intersection of the inner rib and the lateral inner rib. The inner ribs are combined and integrated.
Therefore, the hollow double wall structure having the inner rib of the present invention has higher bending rigidity than the conventional hollow double wall structure having the inner rib.
Moreover, since the empty part is formed in the vicinity of the intersection, the vicinity of the empty part becomes thick and reinforced.
Further, at the time of blow molding, air can be distributed throughout the void.

[First Embodiment]
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional perspective view for illustrating the hollow double-wall structure of the present embodiment.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
The hollow double wall structure A of the present embodiment is a plate-like member formed of a thermoplastic resin, and has a special rib structure in the space formed therein, and has high workability. Can be used for general purposes.
For example, it can be used for vehicle interior panels (so-called deck boards), OA equipment housings, pallets for transportation and transportation.

When the hollow double wall structure A of the present embodiment is used as an interior panel for a vehicle, it is preferable to attach a decorative material 7 such as a nonwoven fabric to the first wall or the second wall of the hollow double wall structure. .
By pasting the decoration material 7, the appearance of the vehicle interior panel is improved and the surface of the vehicle interior panel is hardly damaged.

As shown in FIG. 1, in the hollow double wall structure A, the first wall 21 and the second wall 22 are separated from each other by a predetermined distance. A space V is formed between them.
By forming the space V, the hollow double wall structure A is very light compared to its size.

Also, the inner rib 1 is formed in the space V so as to connect the first wall 21 and the second wall 22.
The inner rib 1 is formed so as to intersect with the space V. Therefore, the hollow double wall structure A exhibits high rigidity with respect to bending in the arrow X direction and bending in the arrow Y direction.

  The inner rib 1 includes a vertical inner rib 11, a horizontal inner rib 12, and an intersecting portion 13, and the vertical inner rib 11 and the horizontal inner rib 12 are formed to be orthogonal.

  The intersecting portion 13 is a solid cross-shaped rib formed at a position where the longitudinal inner rib 11 and the transverse inner rib 12 intersect. The longitudinal inner rib 11 and the transverse inner rib 12 are interposed via the intersecting portion 13. It is integrated and integrated.

Therefore, the inner rib 1 is a continuous and solid rib having no break between the vertical inner rib 11 and the horizontal inner rib 12 of the present embodiment, unlike the conventional vertical inner rib and horizontal inner rib. Yes.
As a result, the rigidity of the hollow double wall structure A is higher than that of a conventional hollow double wall structure with an inner rib.

A substantially semicircular void H is formed in the vicinity of the intersection 13, that is, in the vicinity of the joint between the vertical inner rib 11 and the second wall 22 and in the vicinity of the joint between the horizontal inner rib 11 and the second wall 22. ing.
The reason why the void H is formed will be described later. When the hollow double wall structure A is manufactured by direct blow molding by forming the void H, a pressurized fluid is passed through the void H. Since (air blowing) reaches the parison, it is possible to manufacture with only one air blowing port.

  Specifically, the space V is partitioned into a plurality of small spaces (cells) each surrounded on four sides by the vertical inner rib 11 and the horizontal inner rib 12, but an empty portion H is formed in the vicinity of the intersection 13. Therefore, the pressurized fluid can be circulated throughout without providing the blowing means for each cell.

Further, in the vertical inner rib 11 and the horizontal inner rib 12, the thickness of the portion above the empty portion H is thicker than the thickness of the other portions (see the enclosed portion Q in FIG. 2).
Thus, since a thick part is formed in the inner rib 1, the inner rib 1 has higher strength than an inner rib having no thick part as in the prior art.

In addition, the bend line 5 corresponding to the inner rib 1 is formed in a lattice shape on the surface of the first wall 21, but the vertical slide core mark 6 </ b> A <b> 1 that is a shallow concave groove at a position corresponding to the slide core described later, By forming the slide core mark 6A2 and the horizontal slide core mark 6A3, the position of the bent meat line 5 sinks to the bottom of each slide core mark.
Therefore, it is possible to prevent the folded meat wire 5 from appearing on the surface and the smoothness of the hollow double wall structure A from being lowered.
Each slide core mark is formed by molding in a state where the slide core is slightly protruded from the cavity surface of the mold when the slide core is retracted.

Next, the manufacturing method of the hollow double wall structure of the present embodiment will be described by taking a manufacturing method by direct blow molding as an example.
When the hollow double wall structure of the present embodiment is manufactured by blow molding, the inner rib inserts (injects) the slide core provided in the split mold into the parison before introducing the pressurized fluid. It is formed by stretching a part inside the parison.

A specific manufacturing method is as follows.
As the first step (step of closing the divided mold), so-called mold clamping is performed in which the parison P extruded from a die (not shown) is sandwiched by the divided mold in a pre-blowed state (FIGS. 3A and 4A). )reference).
The split mold according to this embodiment is designed so that the separation distance between the first wall and the second wall of the hollow double wall structure is 25 mm or less.
If the separation distance between the first wall and the second wall exceeds 25 mm, the parison P may be stretched and broken when the slide core, which will be described later, projects into the parison P.

One split mold 3 </ b> A includes a slide core 3 a for forming the vertical inner rib 11, the horizontal inner rib 12, and the intersecting portion 13.
The slide core 3a is a plate-like member that is a part of a mold protruding from the cavity surface. In a normal state, the slide core 3a is placed in the split mold so that the end surface of the slide core 3a is flush with the cavity surface. It is stored.

  As a second step (step of fusing), before the parison P is solidified, the slide core 3a is protruded toward one wall surface of the parison P, and a part of the parison P (hereinafter referred to as “extension portion”). And the extended portion is brought into contact with the other wall surface and fused (see FIGS. 3B and 4B).

As a third step (step of retracting the slide core), the slide core 3a that has been projected toward the parison P is retracted to a position where the end surface is flush with the cavity surface.
When the slide core 3a is pulled out from the parison P, a recess 4 is formed in the portion into which the slide core 3a has been inserted (see FIG. 6A).

Here, the slide core 3a will be described.
FIG. 5 is a perspective view showing the configuration of the slide core.
As shown in FIG. 5, the slide core 3a includes a vertical slide core 3A1, a horizontal slide core 3A3 formed in a direction orthogonal to the vertical slide core 3A1, and a cross slide core 3A2.
The vertical slide core 3A1 is for forming the vertical inner rib 11, the cross slide core 3A2 is for forming the intersecting portion 13, and the horizontal slide core 3A3 is for forming the horizontal inner rib 12.

  The vertical slide core 3A1 and the cross slide core 3A2 are alternately arranged on the straight line with a predetermined interval. Similarly, the horizontal slide core 3A3 and the cross slide core 3A2 have a predetermined interval on the straight line. Are alternately arranged.

The length of the vertical slide core 3A1 and the horizontal slide core 3A3 is preferably about 20 to 125 mm.
The width of the vertical slide core 3A1 and the horizontal slide core 3A3 is preferably about 1 to 7 mm.
The lengths of the four arms of the cross slide core 3A2 are preferably all equal, and the lengths of these arms are preferably about 2 to 10 mm.

The distance d1 between the vertical slide core 3A1 and the cross slide core 3A2 is preferably d1 <L, where L is the thickness of the hollow double wall structure.
If d1 ≧ L, the hollow double-wall structure A may be molded in a state where the vertical inner rib 11 and the intersecting portion 13 are not securely coupled.
Similarly, the distance d2 between the horizontal slide core 3A3 and the cross slide core 3A2 is preferably d2 <L for the same reason as described above.

Furthermore, the interval at which the intersection 13 is formed, that is, the interval (formation pitch) d3 at which the cross slide core 3A2 is formed is preferably L <d3 <5L, and more preferably 2L ≦ d3 ≦ 3L. is there.
When the formation pitch d3 is shorter than L, the interval between the cross slide cores 3A2 is too narrow, and the parison is excessively stretched, so that molding defects are likely to occur.
Further, when the formation pitch d3 is longer than 5L, the number of the longitudinal inner ribs 11 and the lateral inner ribs 12 formed in the hollow double wall structure A is reduced, and the rigidity of the hollow double wall structure A is sufficient. It is no longer a thing.

The end surfaces of the three slide cores are on the same plane, and move in unison while maintaining that state.
However, if the vertical inner ribs 11 and the horizontal inner ribs 12 are connected, and the void H is formed on the second wall side in the vicinity of the intersection 13, the shape of the intersection 13 is adjusted. Thus, it is possible to reduce the height of the cross slide core 3A2 or to eliminate the cross slide core 3A2.
In this case, the intersecting portion 13 is not welded to the inner surface of the second wall 22, but becomes a cruciform bend to connect the longitudinal inner rib 11 and the lateral inner rib 12, and A relatively large void H is formed between the inner surface and the inner surface.

Since the vertical slide core 3A1 and the cross slide core 3A2 are arranged at a predetermined interval, as shown in FIG. 4 (B), either the vertical slide core 3A1 or the cross slide core 3A2 of the parison P is used. The portion that does not contact is pulled and stretched because it is not directly molded by the slide core 3a.
However, it is not fully stretched but is loosened, and is not welded to the inner surface of the second wall 22 but is folded by the subsequent blowing of pressurized air to form a so-called folded meat, forming part of the inner rib.

As a result, a void H is formed between the portion extended by the vertical slide core 3A1 and the portion extended by the cross slide core 3A2.
The wall thickness of the parison P on the first wall side above the empty portion H is thicker than the wall thickness of the other parison P.
Therefore, in the product state, the thickness of the vertical inner rib 11 and the horizontal inner rib 12 above the empty portion H (see the enclosed portion Q by the broken line in FIG. 2) is compared with the thickness of the other portions. It becomes thicker.
Naturally, the thick part has higher rigidity than the other parts.

  Similarly, the cross slide core 3A2 and the horizontal slide core 3A3 (not shown) are also arranged at a predetermined interval. For the same reason as described above, the cross slide core 3A3 and the cross slide core 3A2 A void H is formed between the stretched portion.

Returning to the manufacturing method of the hollow double-walled structure, as a fourth step of the manufacturing method (step of introducing the pressurized fluid), the pressurized fluid is supplied from the blowing port (blow pin) pierced by the parison P. Introducing the parison P expands along the shape of the split mold.
At this time, since the void H is formed, if at least one blowing port is provided, the pressurized fluid passes through the void H and reaches every corner of the parison P.
As described above, the longitudinal inner ribs 11, the lateral inner ribs 12 and the intersecting portions 13 are continuously formed, so that the continuous straight bend line 5 intersects with the root of the intersecting portion 13 as an intersection. , Formed on the surfaces of the first wall 21 and the second wall 22.

When the pressurized fluid is introduced into the parison P, as shown in FIG. 6 (B), the concave portion 4 is folded and closed by the blow pressure so that the parison 4 is closed and fused, so that the inner rib 1 is solid. It is formed.
More specifically, the concave portion 4 formed by the vertical slide core 3A1 becomes the vertical inner rib 11, and the concave portion 4 formed by the cross slide core 3A2 becomes the intersecting portion 13 and is formed by the horizontal slide core 3A3. The recess 4 becomes a lateral inner rib 12.

After the introduction of the pressurized fluid, the split mold is cooled to cure the vertical inner ribs 11, the horizontal inner ribs 12, and the intersecting portions 13, and to completely integrate them.
When each inner rib is completely cured, the split mold 3 is opened and the hollow double wall structure A is taken out.
This completes the production of the hollow double wall structure.

In the second step, when projecting the slide core 3a, it is preferable to vacuum-suck air between the mold cavity and the parison P from the gap between the mold cavity and the sliding portion of the slide core 3a.
By performing vacuum suction, the parison can be drawn to the base portion of the slide core 3a.
This can prevent the base of the formed inner rib from becoming thin.

(Second Embodiment)
By the way, depending on the usage mode of the hollow double-walled structure, a distance between the first wall and the second wall, that is, a thickness exceeding 25 mm may be required.
When manufacturing such a thing with large thickness, if the manufacturing method as described in the first embodiment is used, the protruding distance of the slide core becomes long, and the extension portion becomes thin and may be broken.
Therefore, the method of projecting the slide core from each mold simultaneously is adopted.

A method for producing a hollow double-walled structure in which the slide core is projected at the same time will be described using direct blow molding.
In this case, the difference from the manufacturing method in the first embodiment described above is that both the first mold and the second mold constituting the split mold include a slide core.

As a first step (step of closing the divided mold), the parison P is disposed between the divided molds 3 and then the mold is closed while pre-blowing (see FIG. 7A).
Here, as described in the first embodiment, the parison is drawn to the root portion of the extended portion where the blow ratio is the highest by performing vacuum suction from the gap between the slide core and the mold cavity. It is possible to prevent the molding failure due to the rupture of the parison P, and further to prevent the base of the formed inner rib from becoming thin.

As the second step (the step of fusing), before the parison P is solidified, the slide core 3a provided on the first mold 3A is directed toward one wall surface of the parison P and at the same time the second mold 3B. The slide core 3b provided on the side of the parison P is slowly projected toward the other wall surface of the parison P.
A portion (hereinafter referred to as “upward extension portion”) stretched by the slide core 3a (vertical slide core 3A1, horizontal slide core 3A3, cross slide core 3A2) and a slide core 3b (vertical slide core 3B1, horizontal slide) The slide core 3a and the slide core until the portions extended by the core 3B3 and the cross slide core 3B2) (hereinafter referred to as the “lower extension portion”) are abutted with each other at a substantially intermediate position in the space V and are abutted and fused. 3b is moved (see FIG. 7B).

At this time, the parison P between the vertical slide core 3A1 and the cross slide core 3A2 and between the horizontal slide core 3A3 and the cross slide core 3A2 is fused in the boundary region between the upper extension portion and the lower extension portion. It becomes a flesh-like shape without being broken.
As a result, a void H is formed between the vertical slide core 3A1 and the cross slide core 3A2, and a void H is also formed between the horizontal slide core 3A3 and the cross slide core 3A2.
For this reason, the inner rib 1 to be formed is not excessively stretched at the intersecting portion, and the burst due to the thin wall is suitably prevented.

Then, a portion having a wall thickness thicker than the other portion is generated from the empty portion H to the upper extending portion side, and similarly, a portion having a thick wall thickness is formed from the empty portion H to the lower extending portion side.
Therefore, in the product state, the wall thickness of the vertical inner rib 11 and the horizontal inner rib 12 in the upper and lower portions of the hollow portion H (see the enclosed portion Q by the broken line in FIG. 11) is compared with the wall thickness of the other portions. And thicken.
Naturally, the portion with the large wall thickness has high rigidity.

  Note that the slide cores provided in the first mold 3A and the second mold 3B used at this time are also composed of a vertical slide core, a horizontal slide core, and a cross slide core, as in the first embodiment. The arrangement of each slide core is the same.

That is, the vertical slide core 3A1 and the cross slide core 3A2 included in the first mold 3A are alternately arranged on the straight line with a predetermined interval, and the horizontal slide core 3A3 and the cross slide core 3A2 are also on the straight line. They are alternately arranged at predetermined intervals.
The vertical slide core 3B1 and the cross slide core 3B2 provided in the second mold 3B are alternately arranged on the straight line with a predetermined interval, and the horizontal slide core 3B3 and the cross slide core 3B2 are also on the straight line. They are alternately arranged at predetermined intervals (see FIG. 8).

The distance d1 between the vertical slide core 3A1 and the cross slide core 3A2 is preferably d1 <L, where L is the thickness of the hollow double wall structure, and the horizontal slide core 3A3 and the cross slide core 3A2 The distance d2 is preferably d2 <L.
The formation pitch d3 of the cross slide core 3A2 is also preferably h <d3 <5L, and more preferably 2L ≦ d3 ≦ 3L.

Similarly, the distance d1 between the vertical slide core 3B1 and the cross slide core 3B2 is preferably d1 <L, where L is the thickness of the hollow double wall structure, and the horizontal slide core 3B3 and the cross slide core The distance d2 from 3B2 is preferably d2 <L.
The formation pitch d3 of the cruciform slide core 3B2 is also preferably h <d3 <5L, and more preferably 2L ≦ d3 ≦ 3L.

As a third step (step of retracting the slide core), the slide core 3a and the slide core 3b protruding toward the parison P are retracted to positions where their respective end surfaces are flush with the cavity surface (FIG. 7 ( C)).
When the slide core 3a and the slide core 3b are pulled out from the parison P, a recess 4 is formed in the portion into which the slide core 3a and the slide core 3b are inserted (see FIG. 9A).

As a fourth step (step of introducing a pressurized fluid), the pressurized fluid is introduced from a blowing port (blow pin) pierced by the parison P, and the parison P is expanded along the shape of the split mold.
At this time, since the void H is formed, if at least one blowing port is provided, the pressurized fluid passes through the void H and reaches every corner of the parison P.

  When the pressurized fluid is introduced into the parison P, as shown in FIG. 9B, the recess 4 is closed and fused by the blow pressure, and the recess 4 formed by both slide cores becomes the inner rib. 1

After the introduction of the pressurized fluid, the split mold 3 is cooled to cure the vertical inner ribs 11, the horizontal inner ribs 12, and the intersecting portions 13 so that they are completely integrated. When each inner rib is cured, the split mold 3 is opened and the hollow double wall structure A is taken out.
Thus, the production of the hollow double wall structure is completed.
FIG. 10 is a cross-sectional perspective view of a hollow double wall structure manufactured by this manufacturing method, and FIG. 11 is a cross-sectional view taken along line AA of FIG.

Thus, by projecting the slide core from both sides of the parison (that is, from each mold), the moving distance of the slide core can be suppressed to half the thickness of the hollow double wall structure.
As a result, it is not necessary to stretch the parison excessively when forming the inner rib, and the possibility of the parison being broken can be eliminated as much as possible.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, the number of inner ribs formed in the hollow double wall structure of the present invention, the thickness, the number of intersections, and the like are appropriately set according to the purpose of use of the hollow double wall structure.
When the hollow double wall structure of the present invention is used for a vehicle interior panel (1000 mm × 500 mm), the number of intersecting portions formed vertically and horizontally is 50 to 500, and the number of formed inner ribs is 5 vertically and horizontally, respectively. It can be said that it is sufficient if ˜30 and the thickness is secured to about 1 to 5 mm.
Here, for reference, FIG. 12 shows a usage mode of the vehicle inner layer panel using the hollow double wall structure of the present invention.

Moreover, although the manufacturing method of the hollow double wall structure of this invention was demonstrated to the example of direct blow molding, the hollow double wall structure of this invention can also be manufactured also by sheet blow molding.
Moreover, rigidity can be further improved by disposing a reinforcing member (so-called reinforcement) in the manufactured hollow double wall structure.

FIG. 1 is a cross-sectional perspective view showing a hollow double wall structure according to a first embodiment. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a cross-sectional view showing a molding process of the hollow double wall structure according to the present invention. 4 is an enlarged view of FIG. 3, in which (A) is a cross-sectional view taken along line AA in FIG. 3 (A), (B) is a cross-sectional view taken along line BB in FIG. 3 (B), and (C) is FIG. (C) It is sectional drawing of CC. FIG. 5 is an explanatory diagram showing the configuration of the slide core. FIG. 6 is a cross-sectional view showing the process of forming the inner rib. FIG. 7A is a cross-sectional view showing a molding process of the hollow double wall structure according to the second embodiment. FIG. 7B is a cross-sectional view showing a molding process of the hollow double wall structure according to the second embodiment. FIG. 7C is a cross-sectional view showing a molding process of the hollow double wall structure according to the second embodiment. FIG. 8 is an explanatory diagram showing the configuration of the slide core in the second embodiment. FIG. 9 is a cross-sectional view showing a state when the slide core is pulled out from the parison. FIG. 10 is a cross-sectional perspective view for illustrating the hollow double wall structure according to the second embodiment. 11 is a cross-sectional view taken along line AA in FIG. FIG. 12 is an explanatory view showing a usage mode of the vehicle interior panel using the hollow double wall structure of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner rib 11 ... Vertical inner rib 12 ... Horizontal inner rib 13 ... Crossing part 21 ... 1st wall 22 ... 2nd wall 3 ... Split mold 3a ... Slide core 3b ... Slide core 3A ... Split mold 3B ... Split mold 3A1 ... Vertical slide core 3A2 ... Cross slide core 3A3 ... Horizontal slide core 3B1 ... Vertical slide Core 3B2 ... Cross slide core 3B3 ... Horizontal slide core 4 ... Recess 5 ... Folded wire 6A1 ... Vertical slide core trace 6A2 ... Cross slide core trace 6A3 ... Horizontal slide core Trace 7 ... Decorative material A ... Hollow double wall structure H ... Empty part P ... Parison V ... Space

Claims (10)

A hollow double wall structure in which a first wall and a second wall made of a thermoplastic resin are separated from each other,
In the space formed between the first wall and the second wall, a vertical inner rib, a horizontal inner rib that goes directly to the vertical inner rib, and a cross-shaped intersection are formed,
While the vertical inner rib is connected to the horizontal inner rib through the intersection,
A hollow double-walled structure having a rib structure in which voids are formed in the vicinity of the intersection.   The distance between the first wall and the second wall is 25 mm or less, and the longitudinal inner rib and the lateral inner rib are formed by abutting and fusing the extended first wall to the second wall. The hollow double-walled structure according to claim 1, wherein:   The separation distance between the first wall and the second wall is greater than 25 mm, and the longitudinal inner rib and the lateral inner rib are approximately halfway between the extended first wall and the extended second wall. The hollow double-wall structure according to claim 1, wherein the hollow double-wall structure is formed by abutting fusion at a position.   4. The hollow double wall structure according to claim 2, wherein the intersecting portion is solid. A method for producing a hollow double wall structure using a split mold comprising a first mold and a second mold,
The first mold includes a slide core for extending the parison,
The slide core includes a vertical slide core forming a vertical inner rib, a horizontal slide core disposed in a direction perpendicular to the vertical slide core, and a cross slide core disposed with a space between the vertical slide core and the horizontal slide core. And consist of
Disposing a thermoplastic resin parison in a molten state between the split molds, placing the parison, and then closing the split mold;
Stretching the wall surface of one parison by the slide core protruding from the cavity surface of the first mold, and abutting and fusing the wall surface of the other parison,
After fusing part of the wall surface of the parison, withdrawing the slide core from the parison and retracting it to the cavity surface of the mold,
A step of retracting the slide core and then introducing a pressurized fluid into the parison.   6. The method for producing a hollow double wall structure according to claim 5, which is used when producing a hollow double wall structure having a thickness of 25 mm or less. Before closing the split mold, by placing the skin material between the second mold and the parison,
6. The method for producing a hollow double-walled structure according to claim 5, wherein the back surface of the skin material is integrally attached to the wall surface of the parison. A method for producing a hollow double wall structure using a split mold comprising a first mold and a second mold,
The first mold and the second mold include a slide core for extending a parison,
The slide core includes a vertical slide core forming a vertical inner rib, a horizontal slide core arranged in a direction perpendicular to the vertical slide core, and a cross slide core arranged with a space between the vertical slide core and the horizontal slide core. And consist of
Disposing a thermoplastic resin parison in a molten state between the split molds, placing the parison, and then closing the split mold;
The slide core is projected from the cavity surface of the first mold and the second mold, and the wall surface of the parison stretched inward by the slide core of the first mold and stretched inward by the slide core of the second mold. The process of affixing the wall of the parison
After fusing part of the wall surface of the parison, withdrawing both slide cores from the parison to the cavity surface of the mold,
A step of retracting the slide core and then introducing a pressurized fluid into the parison.   The method for producing a hollow double-walled structure according to claim 8, which is used when producing a hollow double-walled structure having a thickness exceeding 25 mm. The method for producing a hollow double-walled structure according to claim 5 or 8, wherein vacuum suction is performed from a gap between the slide core and the mold cavity.

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