JP2001239573A - Manufacturing method for hollow body and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hollow body which shows high rigidity and strength properties due to its advantage that an inner rib having an appropriate wall thickness and a uniformly trimmed configuration as a whole can be formed. SOLUTION: The device for manufacturing a hollow body by blow molding a thermoplastic resin is constituted of a pair of split halves of a mold with a slide core 13 for forming the inner rib which integrally connects one wall to the other wall in a hollow part. The slide core 13 slides its way forward to and backward from a cavity face, and at a position where the slide cores 13 are held, supporting cores are provided which support a wall 15 formed protruding from a parison (a) by means of the slide cores 13. Thus the part of the wall 15 formed protruding from the parison (a) is prevented from being dragged by the slide cores 13 during the receding thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a hollow body obtained by blow molding a thermoplastic resin, the hollow body having a rib for integrally connecting one wall and the other wall in a hollow portion. A method and an apparatus therefor.

[0002] The hollow body according to the present invention is used for various ducts for air conditioning and the like, housing equipment, furniture panels, housings of home appliances, housings of office equipment, panels of automobile parts, and the like.

[0003]

2. Description of the Related Art Housing equipment includes bathroom panels, wash basins, wall materials, partitions, entrance doors, air conditioning ducts, and the like. Furniture panels include desk tops, partition panels, and the like.
Bookshelves, etc. Further, the housing of the home electric appliance includes a housing of a refrigerator, a housing of a television, and the like. The housing of the office equipment includes a housing of a copying machine and a door thereof. Panels for automobiles include console box lids, bonnets and doors.

[0004] Since high rigidity is often required for housing equipment, furniture panels, housings for home electric appliances, housings for office equipment, panels and ducts for automobile supplies, hollow housings are used for such purposes. The body has a structure in which one wall and the other wall are integrated by a rib that connects each other in the hollow portion. Particularly, when the appearance of both sides is emphasized, one wall and the other wall are blow molded. And a rib having a so-called inner rib, which is made to protrude until a part of the other wall comes into contact with the one wall and is integrally connected in the hollow portion, is used (JP-A-5-25400).
No. 1).

[0005]

The inner rib of the above-mentioned hollow double-walled structure is clamped by disposing a parison of a thermoplastic resin between a pair of split molds, and sliding the inner rib on the other mold. By protruding the core from the cavity surface or by protruding the slide core from the cavity surface before mold clamping, both the walls are welded by projecting part of the other wall until it comes into contact with one wall during mold clamping. Then, the slide core is retracted to the cavity surface of the other mold, and the side surfaces of the protruded walls are welded to each other by blow pressure to form an integral inner rib between one wall and the other wall. Since the process of forming the slide core is followed, a phenomenon in which the protruding wall is dragged in the retreating direction of the slide core in the process of retracting the slide core is exhibited.

[0006] For this reason, especially when the thickness of the hollow body is large, the inner rib formed in the hollow portion is partially formed thin or has irregularities such as formation of holes, and the reinforcing effect of the inner rib is reduced. It decreases significantly. In the molding method in which the inner rib is formed from one wall, the thickness of the hollow double-walled structure may be up to 30 mm, and even in the method in which the inner rib is formed from both walls, the thickness may be up to 40 mm, which is a limit for forming the inner rib properly. Do you get it.

In view of the above, the present invention is to overcome such a technical limit. A support core is provided at a position sandwiching the slide core, and the slide core is left at the projecting position. The wall portion protruded by the slide core of the parison is supported by the support core by retreating or retreating the support core later than the retraction of the slide, and the wall portion of the parison protrudes with the retraction of the slide core. By eliminating the drag phenomenon, the side surfaces of the wall portions protruded by the slide core are welded to each other by blow pressure to form an integral rib between one wall and the other wall,
It is an object of the present invention to provide a method and an apparatus for manufacturing a hollow body capable of manufacturing a hollow body having excellent rigidity and strength by forming a uniform inner rib with an appropriate thickness throughout. It is.

[0008]

In order to achieve the above object, a method for manufacturing a hollow body according to claim 1 of the present invention is a method for manufacturing a hollow body by blow molding a thermoplastic resin. The split mold includes a slide core for forming a rib that integrally connects one wall and the other wall within the hollow portion, and a support core at a position sandwiching the slide core. A parison made of thermoplastic resin is placed between the split molds with the slide core and support core protruding from the cavity surface, and the mold is clamped to oppose the wall part where the parison is protruded by the slide core and the support core The parison is welded, then the slide core is retracted, and a pressure fluid is introduced into the parison to form the parison into a shape along the cavity surfaces of the pair of split molds, The side of the serial wall portion is protruded by the slide cores is characterized in that to form an integral rib between the welding to one wall and the other wall to each other by blow pressure.

According to a second aspect of the present invention, in the method of the first aspect, the blow molding is performed by introducing a pressure fluid into the parison while the support core is projected from the cavity surface. It is a feature.

[0010] According to a third aspect of the present invention, there is provided a method of manufacturing a hollow body, wherein the support core is retracted behind the slide core.

According to a fourth aspect of the present invention, there is provided a hollow body manufacturing apparatus for manufacturing a hollow body by blow molding a thermoplastic resin, wherein one wall and the other wall are formed in the hollow portion. It is composed of a slide core that forms a rib that integrally connects with each other, and a pair of split molds having a support core at a position sandwiching the slide core. The slide core projects and retracts from the cavity surface of the mold. In this case, the support core is configured to be retracted while being protruded from the cavity surface or later than the slide core is retracted.

According to a fifth aspect of the present invention, there is provided an apparatus for manufacturing a hollow body according to the fourth aspect, wherein the slide core has a surface subjected to a fluorine coating treatment on the parison so as to be slippery. It is a feature.

[0013]

FIG. 1 is a perspective view showing an air conditioning duct as an example of a hollow body according to one embodiment of the present invention. 2 to 9 show a blow molding mode of a hollow body according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a state in which a parison is arranged between a pair of open split dies as viewed from a side of a duct. , FIG. 3 is a cross-sectional view showing a state where the mold is clamped from the state of FIG. 2, FIG. 4 is a horizontal cross-sectional view corresponding to FIG. 3, and FIG. 5 is a cross-sectional view showing a state where the slide core is retracted and blow molded. 6 is a horizontal sectional view corresponding to FIG. 5, FIG. 7 is a sectional view showing a state where the mold is opened after blow molding, FIG. 8 is a sectional view corresponding to FIG. 3 showing another embodiment, and FIG. 9 is FIG. FIG. 7 is a cross-sectional view showing a state in which the support core is retracted behind the slide core from the state shown in FIG. FIG. 10 is a partial view of a duct showing still another embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a duct, and the duct 1 is formed by blow molding a thermoplastic resin. One wall 2 and the other wall 3 constituting the duct 1
Are integrated in the hollow portion 5 by the inner ribs 4 formed so as to abut each other from both the one wall 2 and the other wall 3. Numerals 6 and 6 are connecting portions of the duct.
A shallow concave portion 7 is formed in one wall 2 and the other wall 3 in a portion of the duct 1 where the inner rib 4 is formed. , 8 are formed.

The thermoplastic resin constituting the duct 1, which is a hollow body according to the present invention, may be any one that can be blow-molded. However, high-density polyethylene resin, medium-density polyethylene resin, polypropylene resin, modified polyphenylene oxide resin, Polycarbonate resin, polyamide resin, polystyrene resin, ABS resin and the like are suitable.

The duct 1 according to the present invention is shown in FIGS.
Is manufactured by blow molding a thermoplastic resin. In these figures, a pair of split molds is composed of one mold 11 and the other mold 12, and one mold 11 is connected to one wall 2 of the hollow double-walled structure 1 and the other mold. 12 has a cavity for molding the other wall 3. Then, one mold 11 and the other mold 12
Is a slide core 1 for forming the inner rib 4.
3, 13, and a pair of support cores 14, 14 are provided at positions sandwiching each slide core 13. The pair of support cores 14, 14 always protrude from the cavities of the one mold 11 and the other mold 12 by the same length as the protrusion of the slide core 13.

Each of the slide cores 13 may have a coating layer made of a fluororesin which is slippery on the parison on its surface. If the surface of the slide core 13 is roughened and a fluororesin coating layer is formed on the surface of the slide layer, the fluorocarbon resin coating layer can be formed firmly.

The coating layer may be a thin layer made of a fluororesin, or may be co-deposited with a fluororesin and a plating solution such as electroless nickel in a treatment solution, and the treatment solution may be applied to the surface of the sliding mold. It can be applied and fired to form a coating layer. Alternatively, a coating layer can be formed by forming an electroless nickel film on the surface of the slide core 13 and impregnating the electroless nickel film with a fluorine-based resin.

In order to blow-mold the duct 1 using the pair of split molds, one open mold 11 and the other open mold 1 are used.
2 and the parison a is arranged (FIG. 2), and the pair of split molds are clamped with the slide core 13 advanced (FIG. 3). Then, when the mold is clamped in this manner, a portion serving as one wall 2 of the parison a and a portion of the portion serving as the other wall 3 protrude in the hollow portion 5 by the slide cores 13 until they abut each other. , Its protruding walls 15, 15
Are welded to each other.

Next, the slide core 13 is retracted and a pressure fluid is introduced into the parison a to form the parison a along the cavities of the pair of dies. Support core 1
4 and 14 remain protruding, so that the slide core 13
With the retreat, the phenomenon that the walls 15, 15 protruded by the slide core 13 of the parison a are not dragged.

For this reason, in the blow molding step, the protruding walls 15, 15 which become the inner ribs 4, are formed in an appropriate wall thickness and in a uniform form even when the thickness of the duct 1 is large. Therefore, the duct 1 having excellent rigidity and strength can be manufactured.

The blow-molded duct 1 is taken out by cooling the pair of split dies and then opening the dies (FIG. 7).

In another embodiment shown in FIGS. 8 and 9, the support core 1 for each slide core 13 is provided.
4 and 14 are configured to protrude and retreat from the cavity surface, and retreat with a delay from the slide core 13. However, during the retraction of the slide core 13, the wall protruded by the slide core 13 of the parison a. Since the support cores 15 and 15 continue to be supported by the support cores 14 and 14, the inner ribs 4 are formed into a uniform shape with a proper wall thickness as in the case of the first embodiment. Then, as in this embodiment, the support cores 14, 14 are retracted, so that the parison a becomes the support core 1 in the blow molding process.
Since the cavities formed by the pipes 4 and 14 are completely filled, the cavities 8 and 8 are not formed in the duct 1 as in the above-described embodiment.

The duct 1 shown in FIG.
2 is inclined. In the form in which one wall 2 is inclined as described above, the inclined one wall 2 and the inner rib 4 do not form an angle orthogonal to each other, but the inner rib 4 is orthogonal to the other wall 3. It is preferable from the standpoint of strength that it is formed in a state of rising at an angle.

[0025]

According to the present invention, a support core is provided at a position sandwiching a slide core and the slide core is retracted while the support core is left at the projecting position, or the support core is retracted later than the slide retreat. Thereby, the wall portion protruded by the slide core of the parison is supported by the support core, so that the drag phenomenon of the wall portion protruded by the parison is eliminated with the retraction of the slide core, and the wall portion protruded by the slide core is removed. The side walls are welded to each other by blow pressure to form an integral rib between one wall and the other wall, so that a uniform inner rib with an appropriate thickness can be formed as a whole,
A hollow body having excellent rigidity and strength can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an air conditioning duct as an example of a hollow body according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a parison is arranged between a pair of opened split dies as viewed from a side surface of a duct, showing a blow molding mode of a hollow body according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state where the mold is clamped from the state of FIG. 2;

FIG. 4 is a horizontal sectional view corresponding to FIG.

FIG. 5 is a sectional view showing a state in which the slide core is retracted and blow molded.

FIG. 6 is a horizontal sectional view corresponding to FIG.

FIG. 7 is a cross-sectional view showing a state where a mold is opened after blow molding.

FIG. 8 is a cross-sectional view corresponding to FIG. 3, showing another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a state in which the support core is retracted behind the slide core from the state of FIG. 8;

FIG. 10 is a partial view of a duct showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Duct 2 One wall 3 The other wall 4 Inner rib 5 Hollow part 6 Connection part 7 Depression part 8 Cavity part 11 One mold 12 The other mold 13 Slide core 14 Support core 15 Projected wall a Parison

Claims (5)

[Claims] 1. A method for producing a hollow body by blow molding a thermoplastic resin, wherein a pair of split molds is provided with a rib for integrally connecting one wall and the other wall to each other in a hollow portion. A slide core for forming, and a support core at a position sandwiching the slide core, a parison of thermoplastic resin with the slide core and the support core protruding from the cavity surface between the pair of split molds. And the mold is clamped to weld the parison with the wall portion protruded by the slide core and the support core to the opposing parison.Then, the slide core is retracted, and a pressurized fluid is introduced into the parison to join the parison to the pair of parisons. The mold is formed into a shape along the cavity surface of the split mold, and the side surfaces of the wall portions protruded by the slide core are welded to each other by blow pressure to form one of the walls. A method for manufacturing a hollow body, wherein an integral rib is formed between the hollow body and the other wall. 2. The method according to claim 1, wherein a pressure fluid is introduced into the parison and blow molding is performed while the support core is projected from the cavity surface. 3. The method for manufacturing a hollow body according to claim 1, wherein the support core is retracted behind the slide core. 4. An apparatus for producing a hollow body by blow-molding a thermoplastic resin, said slide core forming a rib for integrally connecting one wall and the other wall to each other in a hollow portion, and said slide core. The slide core is configured to protrude and retreat from the cavity surface of the mold, and the support core is kept protruding from the cavity surface or the slide core. An apparatus for manufacturing a hollow body, wherein the apparatus is configured to retreat later than retreat. 5. The apparatus for manufacturing a hollow body according to claim 4, wherein the slide core has a surface coated with a fluorine coating which is slidable on a parison.