JP2001239576A - Method for manufacturing hollow double-wall structure and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hollow double-wall structure which shows outstanding rigidity and strength properties with such an advantage that an inner rib with an appropriate wall thickness and a uniformly trimmed configuration as a whole can be formed even when the hollow double-wall structure intended for manufacturing is of a large thickness. SOLUTION: Before a pair of split halves of a mold are clamped together, a slide mold 13 is protruded from a cavity face and the part of a parison which is extruded by the slide mold 13 is brought into contact under pressure with the opposite parison. Then the slide mold 13 is actuated under control to slowly make it recede in relation to a blowing process to introduce a pressure fluid into the parison.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow double-walled structure obtained by blow-molding a thermoplastic resin and having a rib for integrally connecting one wall and the other wall in a hollow portion. The present invention relates to a method and an apparatus for manufacturing a hollow double-walled structure.

[0002] The hollow double-walled structure according to the present invention is used for housing equipment, furniture panels, housing of home electric appliances, housing of office equipment, panels of automobile supplies and the like.

[0003]

2. Description of the Related Art Household equipment includes bathroom panels, wash basins, wall materials, partitions, entrance doors, and the like, and furniture panels include desk tops, partition panels, and bookshelves. 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 housing equipment, furniture panels, home appliance housings, office equipment housings, and automotive supplies panels are often required to have high rigidity, hollow hollows used for such applications are required. As the wall structure, a structure in which one wall and the other wall are integrated by a rib connecting each other in the hollow portion is used. In particular, when emphasizing the appearance of both surfaces, one wall is used in blow molding. And a rib having a so-called inner rib, which is formed by projecting the other wall and a part of the other wall so as to come into contact with the one wall, and integrally connecting them in the hollow portion, is used (JP-A-5-254).
001).

[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. Advance the core or advance the sliding mold before closing the mold so that a part of the other wall is protruded until it comes into contact with one wall and both walls are welded. Since the mold is retracted to the cavity surface of the mold, and the side surfaces of the protruded walls are welded to each other by blow pressure to form an integral rib between one wall and the other wall, When the sliding die is rapidly retracted, a phenomenon occurs in which the wall protruded in the retracting process is dragged in the retracting direction.

[0006] Therefore, when the thickness of the hollow double-walled structure is large, the inner ribs formed in the hollow portion are partially thinned or have irregularities such as formation of holes, and the like.
The reinforcing effect of the inner rib is significantly reduced. In the forming method of forming the inner rib from one wall, the thickness of the hollow double-walled structure is 30 mm or less, and even in the method of forming the inner rib from both walls, 40 mm is the limit that the inner rib can be formed properly. Do you get it.

Accordingly, the present invention addresses such technical limitations, and retreats the sliding die at a slow speed, while the side surface of the wall protruded by the sliding die. Are welded to each other by a blow pressure to form an integral rib between one wall and the other wall, so that even if the hollow double-walled structure has a large thickness, the overall thickness is appropriately adjusted. It is an object of the present invention to provide a method and apparatus for manufacturing a hollow double-walled structure capable of forming a balanced inner rib at the same time and manufacturing a hollow double-walled structure excellent in rigidity and strength. Is what you do.

[0008]

According to a first aspect of the present invention, there is provided a method for manufacturing a hollow double-walled structure, comprising blow molding a thermoplastic resin to form a hollow double-walled structure. A method of manufacturing, wherein a sliding mold is provided between a pair of split molds having a sliding mold that forms a rib integrally connecting one wall and the other wall within a hollow portion. After the parison of thermoplastic resin is placed in a state where it protrudes from the parison and the mold is clamped, the part extruded by the sliding die of the parison is pressed against the opposing parison, and immediately after the sliding mold retreats immediately after retreat During this time, pressurized fluid is introduced into the parison to form the parison along the cavities of the pair of molds, and then the sliding mold is retracted at a slow speed. Of the wall protruded by the sliding mold It is intended to and forming an integral rib between one wall and the other wall are welded to each other by blow pressure surface.

According to a second aspect of the present invention, there is provided a method for manufacturing a hollow double-walled structure according to the first aspect, wherein the retreat speed of the sliding mold is set to 15 to 100 mm / sec. Things.

A third aspect of the present invention is an apparatus for manufacturing a hollow double-walled structure by blow molding a thermoplastic resin, wherein one wall and the other wall are manufactured. And a pair of split molds provided with a sliding mold that integrally forms a rib in the hollow portion, and an air cylinder and an air control device for moving the sliding mold forward and backward, The air control device protrudes the sliding die from the cavity surface before clamping, presses the portion extruded by the parison sliding die against the opposing parison, and then introduces a pressure fluid into the parison. It is characterized in that it is configured to perform a control operation for retracting the sliding die at a slow speed in relation to the process.

According to a fourth aspect of the present invention, there is provided an apparatus for manufacturing a hollow double-walled structure, wherein the air control device comprises:
The sliding die has a retreat speed of 15 to 100 mm / sec.

[0012]

FIG. 1 is a perspective view showing a hollow double-wall structure according to an embodiment of the present invention. FIG. 2 is a partially cutaway plan view showing a blow molding mode of the hollow double-walled structure according to one embodiment of the present invention. FIG. 3 is an air cylinder for moving a sliding die forward and backward, and its air. It is a block diagram of a control apparatus. FIGS. 4, 5 and 6 are cross-sectional views of essential parts showing the blow molding mode of the hollow double-walled structure according to one embodiment of the present invention in the order of steps.

In FIG. 1, reference numeral 1 denotes a hollow double-walled structure, and the hollow double-walled structure 1 is a panel formed by blow molding a thermoplastic resin. One wall 2 and the other wall 3 constituting the hollow double-walled structure 1 are integrated by an inner rib 4 formed from the other wall 3 toward the one wall 2.

The thermoplastic resin constituting the hollow double-walled structure 1 according to the present invention is not limited as long as it can be blow-molded. However, high-density polyethylene resin, medium-density polyethylene resin, polypropylene resin, and modified polyphenylene oxide resin are used. , Polycarbonate resin, polyamide resin, polystyrene resin, ABS resin and the like are preferable.

The hollow double-walled structure 1 according to the present invention is shown in FIG.
It is manufactured by blow molding a thermoplastic resin by a blow molding apparatus shown in FIG. 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. The other mold 12 has a sliding mold 13 for forming the inner rib 4.

The sliding die 13 is controlled to advance and retreat by an air cylinder 14 and its air control device 15 shown in FIG. In FIG. 3, 16 is an air tank, 17 is a solenoid valve, and 18 is a flow rate adjusting valve. The air cylinder 14 connected to the sliding die 13 has a forward air circuit 19 and a reverse air circuit 19 so that pressure air is introduced from an air tank 16 via a solenoid valve 17 to the forward and backward sides thereof. A moving side air circuit 20 is formed, and the flow rate adjusting valve 18 is interposed in the moving side air circuit 20.

In the air cylinder 14 and its air control device 15 shown in FIG. 3, when the pressure air is sent to the forward movement side of the air cylinder 14 by the control operation of the solenoid valve 17, the sliding mold 13 is moved to the cavity surface. From the sliding die 13
Recedes from the cavity surface. Since the flow adjustment valve 18 is interposed on the return side, this flow adjustment valve 18 is provided.
By adjusting the backward movement speed of the air cylinder 14, the sliding mold 13 can be moved backward at a slow speed. In the present embodiment, the retreat speed of the sliding mold 13 is set to 15
１００100 mm / sec.

In order to blow-mold the hollow double-walled structure 1 using the pair of split molds, a parison is arranged between one mold 11 and the other mold 12, as shown in FIG. ,
With the sliding mold 13 advanced, the pair of split molds are clamped. When the mold is clamped in this manner, a part of the other wall 3 of the parison a is protruded by the sliding mold 13 until it comes into contact with the one wall 2 of the parison a. Is welded to a portion to be one wall 2 of the parison a.

Next, the sliding die 13 is retracted by the air cylinder 14 and its air control device 15 shown in FIG. 3, and as shown in FIG. During the appropriate time period, a pressurized fluid is introduced into the parison a to form the parison a into a shape along the cavity surfaces of the pair of dies, and then the sliding die 1
6, the side surfaces of the walls 21 protruded by the sliding mold 13 are welded to each other by blow pressure, and the one wall and the other are retreated as shown in FIG. An integral inner rib 4 is formed between the inner rib 4 and the wall. The sliding die 13 can also perform speed change control such as sequentially reducing the retreat speed in the retreat process.

The blow-molded hollow double-walled structure 1 is taken out after cooling a pair of split molds.

In the blow molding step, the protruding wall 21 serving as the inner rib 4 is supported at the tip of the protruding sliding die 13 with respect to the cavity of the other die 12, so that the integral inner rib 4 is formed. Even if a blow pressure is applied in the process of forming the inner mold 4, the inner rib 4 does not shift, and the sliding mold 13 is moved backward at a slow speed of 15 to 100 mm / sec. The inner rib 4 formed by the protruding wall 21 does not cause a phenomenon that the protruding wall 21 is dragged by the retreat.
Is that even if the thickness of the hollow double-walled structure 1 is large, the inner ribs 4 having an appropriate thickness and uniformity can be formed as a whole, and the hollow double-walled structure 1 is excellent in rigidity and strength. The heavy wall structure 1 can be manufactured.

[0022]

According to the present invention, the side surfaces of the walls protruded by the sliding mold are welded to each other by blow pressure while the sliding mold is retreated at a slow speed, and one wall and the other are welded. By forming an integral rib between the inner wall and the inner wall, even with a hollow double-walled structure having a large thickness, an inner rib with a proper thickness and a uniform thickness can be formed as a whole,
A hollow double-walled structure having excellent rigidity and strength can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a hollow double-wall structure according to an embodiment of the present invention.

FIG. 2 is a partially broken plan view showing a blow molding mode of the hollow double-walled structure according to one embodiment of the present invention.

FIG. 3 is a configuration diagram of an air cylinder for moving a sliding die forward and backward, and an air control device thereof.

FIG. 4 is a cross-sectional view showing a blow molding mode of the hollow double-walled structure according to the embodiment of the present invention in the order of steps, and showing a mode in which a sliding die is advanced and the mold is clamped.

FIG. 5 is a cross-sectional view showing a process of slowly retracting the sliding die from the state of FIG.

FIG. 6 is a cross-sectional view showing an embodiment in which a sliding mold is retracted from the state of FIG. 4 to form an inner rib.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow double wall structure 2 One wall 3 The other wall 4 Inner rib 11 One mold 12 The other mold 13 Sliding mold 14 Air cylinder 15 Air control device 16 Air tank 17 Solenoid valve 18 Flow rate adjusting valve 19 Outgoing side air circuit 20 Backward side air circuit 21 Projected wall a Parison

Claims (4)

[Claims] 1. A method for producing a hollow double-walled structure by blow-molding a thermoplastic resin, comprising forming a rib integrally connecting one wall and the other wall within a hollow portion. A parison made of a thermoplastic resin is arranged between a pair of split molds provided with a mold with the sliding mold protruding from the cavity surface and clamped, and a portion extruded by the parison sliding mold. Was pressed against the opposing parison, and a pressurized fluid was introduced into the parison during an appropriate time period between immediately before and after the retreat of the sliding mold to cause the parison to follow the cavity surfaces of the pair of molds. While being formed into a shape, the sliding molds are successively retracted at a slow speed, and the sides of the walls protruded by the sliding molds are welded to each other by blow pressure to form one wall and the other wall. Characterized by forming an integral rib between A method for producing a hollow double-walled structure. 2. The retracting speed of the sliding die is 15 to 100 mm.
2. The method for producing a hollow double-wall structure according to claim 1, wherein 3. An apparatus for producing a hollow double-walled structure by blow-molding a thermoplastic resin, wherein a sliding member is formed to integrally connect one wall and another wall to each other in a hollow portion. It consists of a pair of split molds equipped with a mold, an air cylinder for moving the sliding mold forward and backward, and its air control device. The air control device moves the sliding mold to the cavity surface before clamping. After pressing out the part extruded by the sliding die of the parison to the opposing parison, the sliding die is retracted at a slow speed in connection with the blowing process of introducing the pressure fluid into the parison. An apparatus for manufacturing a hollow double-walled structure, wherein the apparatus has a configuration for performing a control operation to cause the hollow double-walled structure. 4. The air control device according to claim 3, wherein the retreat speed of the sliding die is 15 to 100 mm / sec.
An apparatus for manufacturing the hollow double-walled structure according to the above.