JP2003291208A - Method for manufacturing hollow resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a hollow resin molding which can manufacture a molding having excellent gas barrier properties by simple steps. <P>SOLUTION: The method for manufacturing the hollow resin molding comprises the steps of: bringing one end of a flatting core 30 mounted at a distal end of a conveying arm 62 into contact with an extrusion die 42, and extruding a resin from an annular extrusion port provided at the die 42 to the periphery of the core 30. Thus, a cylindrical preform 14 is extrusion molded, and the core 30 is disposed in the preform. The method further comprises the steps of: retracting the arm 62, setting the preform 14 and the core 30 in a press 50, closing an end of the preform 14 by press forming, and forming the resin molding having the flatting core 30 at an inside of the outer wall formed from the preform 14 itself. The core 30 is vanished from the molding to obtain the hollow resin molding. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a hollow resin molded product.

[0002]

A blow molding method is known as a method for producing a hollow resin molded product (resin hollow molded product). However, in a relatively large resin hollow molded product such as a fuel tank for a vehicle, when manufactured by a blow molding method, there is a large variation in the wall thickness of each part of the molded product (for example, between the minimum wall thickness and the maximum wall thickness). The difference was 4 mm or more). Therefore, it was difficult to stably manufacture a thin-walled molded product. In addition, a resin hollow molded product used for a fuel tank or the like is required to have a high gas barrier property, but since a resin material having a high gas barrier property generally tends to have poor fluidity, a high gas barrier property is obtained by an ordinary injection molding method. It was difficult to manufacture a resin hollow molded article.

[0003]

On the other hand, the present inventor has previously used a sheet of resin having gas barrier properties to wrap the fusible core, and after forming a base material layer of the resin on the outside of the sheet, the fusible middle A method for producing a hollow resin product in which the child is lost has been proposed (see Japanese Patent Laid-Open No. 10-119055). A typical example of the manufacturing method will be outlined with reference to FIGS. 17 and 18. As shown in FIG. 17, two sheets 101 having a gas barrier property (gas permeation preventive property) are arranged above and below the fusible core 104. As shown in FIG.
These sheets 101 are aligned around the fusible core 104, and the seam is heated to fuse (heat seal) the upper and lower sheets 101. As a result, the disappearing core 10
4 is formed to surround the seal portion 102. Then, a resin base material layer is formed on the outside of the sheet 101 by injection molding, stamping molding, or the like. According to such a method, it is possible to manufacture a resin hollow-molded product having less variation in wall thickness as compared with the case where a conventional blow molding method is used.

An object of the present invention is to improve such a manufacturing method and to provide a method capable of manufacturing a molded article having an excellent gas barrier property by a simple process.

[0005]

Means and Actions for Solving the Problems The present inventor has a layer that directly encloses a fusible core (hereinafter, also referred to as “core coating layer”. In FIG. 18, it is composed of two sheets 101. It was considered that the gas leakage from the seal portion is suppressed by shortening the seal length of (1). Then, a method of forming the core coating layer with such a short seal length was created. Furthermore, as a result of shortening the seal length, the resin hollow molding showing sufficient gas barrier properties and / or durability strength by using the core coating layer itself as an outer wall (even when the resin base material layer etc. is not formed on the outside). It was found that the product can be obtained.

In the method for producing a hollow resin product provided by the present invention, a resin preform forming a cylinder having a closed cross section is extruded, and the preform after extrusion is formed at a temperature at which the preform can be continuously formed. The preforming body (lost core) is placed in the cylinder of the preforming body while the preforming body is maintained at Set to. Then, the cylinder end of the preformed body (in which the fusible core is disposed inside) is closed using the pressing device. As a result, a resin molded body having an outer wall formed from the preformed body and having a fusible core inside thereof is formed. Thereafter, the hollow resin product is manufactured by removing the fusible core from the inside of the resin molding.

In the manufacturing method of the present invention, the core coating layer is formed by closing the tube end of a (cylindrical) preform having a closed cross section. In this way, since the preform is extruded into a shape with a closed cross-section in advance, the length of the closed portion (seal length) can be shortened after extrusion. For example, as compared with the case where two sheet-like members (that is, the cross-sections are not closed) (sheet 101) are closed around the fusible core 104 (entire circumference) as shown in FIG. The method can significantly reduce the seal length.
Further, in this manufacturing method, press molding is performed while the extruded preform is maintained at a temperature at which it can be formed (without the extruded preform being cooled and solidified once). As a result, the energy cost can be reduced as compared with the case of reheating the preformed body once cooled and solidified for press molding. Further, since uneven heating of the preform is less likely to occur, the press formability (and thus the sealing property) of this preform is good.

In order to improve the flow of work for setting the extruded preform in the pressing device, the extruded preform is pressed in almost the same direction (without significantly changing the longitudinal inclination). It is preferably set in the device. Since a general-purpose pressing device is mainly of a vertical type, it is possible to realize such a good work flow by performing extrusion molding of the preformed body in a horizontal direction.
That is, a manufacturing method in which a preformed body that is extruded in a lateral direction is set horizontally in a vertical pressing device and the vertical pressing device is driven to close the cylinder end of the preformed body is preferable. In this case, since a general-purpose press device can be used, the equipment cost for carrying out the manufacturing method of the present invention can be kept low.

In the manufacturing method of the present invention, as described above, the extrusion-molded preform is set in the press machine while being maintained at the "moldable temperature". For this reason, if the extrusion molding is performed sideways, the extruded preform may be easily deformed by its own weight. Therefore, it is preferable to convey the preformed body extruded in the lateral direction to the press molding position while holding it by the fusible core arranged in the cylinder. This makes it possible to improve the shape retention of the preform when the preform is conveyed by using the fusible core.

When the preform is laterally extruded, a fusible core is placed in the vicinity of the extrusion die in advance.
It is preferable to extrude the preform around the fusible core as a longitudinal guide. In this case, the preform can be supported by the fusible core while the preform is being extruded. Therefore, the shape of the preform can be maintained even better. Further, according to this aspect, the fusible core can be arranged in the cylinder together with the extrusion molding of the preform. By this,
Even if the clearance between the extinguishing core is inserted after the extruding of the preform is completed, the extinguishing core can be easily arranged inside the preform.

In this fusible core, there are relatively uneven portions (uneven surface) and relatively small uneven portions (depending on the shape of the molded product to be manufactured and the mounting position of insert parts described later). Often has a smooth surface. When the preform is extruded using the fusible core as a guide as described above, it is preferable to arrange the fusible core with the smooth surface facing upward. This improves the flow of the resin extruded along the upper surface of the fusible core (using this upper surface as a guide). As a result, the formability of the preform is improved. On the other hand, when press-molding the preform, the concavo-convex surface of the fusible core disposed inside should oppose in the press direction (vertical direction when using a vertical press machine). Is advantageous in terms of moldability. Therefore, it is preferable to extrude the preform around the smooth surface with the smooth surface facing up, and then press-mold with the uneven surface facing up or down.
In order to arrange the fusible core in this way during extrusion molding and press molding of the preform, the extruded preform is appropriately rotated together with the fusible core placed inside the preform to a pressing device. Can be set. When the smooth surface and the uneven surface have a positional relationship of facing each other, such an arrangement can be realized without rotating the fusible core after extrusion molding of the preform. Further, the fusible core provided inside the preform may be rotated independently of the preform.

An insert part may be installed in advance on the fusible core provided in the cylinder of the preform. Typical examples of insert parts installed when the hollow resin molded product is a fuel tank for vehicles include a cutoff valve, a sub tank or a part of its wall surface, a separator, and the like. By using the fusible core in which the insert component is installed in this manner, a resin hollow molded product having the insert component inside the outer wall formed from the preform itself (preferably, this insert component is integrated with the outer wall). Hollow resin molded product) can be easily manufactured.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is also characterized by being embodied in the following modes.

(Mode 1) In the fusible core, a recess is provided at a position corresponding to a pinch-off portion of the preform (a portion located at a seam between the upper mold and the lower mold during press molding). There is. By using the fusible core having such a structure,
The reliability of closing the pinch-off portion can be improved. As a result, impact resistance and / or gas sealability of the obtained hollow resin molded product are further improved.

(Mode 2) A hollow fusible core is used. This makes it possible to reduce the weight of the fusible core.
It is preferable that the fusible core has a light weight, because the core molding facility and the core transport facility can be downsized.
It also becomes easy to remove (disappear) the fusible core from the resin molding. It is preferable that such a hollow shape fusible core has an opening formed in a part of its wall surface so that the hollow part can communicate with the outside. According to the fusible core having such a configuration, for example, by changing the temperature of the fusible core and / or the preformed body as necessary by moving a fluid in and out of the hollow portion in accordance with the progress of the manufacturing process ( Heating and cooling) can be accelerated.

(Mode 3) An extinguishing core divided into a plurality of sub-cores is used. Since the individual (divided) sub-core is lighter than the entire fusible core, it is possible to reduce the size of the sub-core molding equipment and transportation equipment. In particular, when the fusible core has a hollow shape, it is preferably divided into a plurality of sub-cores in this way. Since each sub-core can be formed into a shape that is easier to mold than a hollow shape, a hollow-shaped fusible core can be easily manufactured by assembling these sub-cores.

(Mode 4) The preform is composed of a wall surface (cylindrical surface) having a gas barrier property. Such a preform has a method in which a resin having a high gas barrier property (for example, an ethylene-vinyl alcohol copolymer resin) is extrusion-molded alone, and a resin having a high gas barrier property and another resin (for example, high-density polyethylene) are overlapped. It can be obtained by a method of extruding those resins so that a layered wall surface is formed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of manufacturing a fuel tank for an automobile by applying the method of the present invention will be specifically described below with reference to the drawings.

<First Embodiment> This embodiment is an example of manufacturing the automobile fuel tank 1 shown in FIG. The fuel tank 1 has a hollow shape defined by an outer wall 10 having a gas barrier property. A part of the outer wall 10 extends in a tubular shape to form a fuel supply hole 12. Through this fuel supply hole 12, a space K formed inside the outer wall 10 (fuel tank 1
It is possible to supply fuel or the like from the outside to the hollow portion of the.
The outer wall 10 has a layer structure (not shown) in which a surface layer mainly composed of high density polyethylene (HDPE) is formed on both sides of a gas barrier layer mainly composed of ethylene-vinyl alcohol copolymer resin (EVOH). .

Inside the outer wall 10, the sub tank peripheral wall 2 is provided.
2, the separator 26 and the cutoff valve 28 are integrally attached. Sub tank peripheral wall 22 is HDP
It is a tubular member made of resin such as E, and one end of the tubular member is joined to the outer wall 10. As a result, the sub tank 20 having the sub tank peripheral wall 22 as the side surface and the outer wall 10 as the bottom surface is formed. The separator 26 is HDPE
It is a perforated plate made of resin such as, and has one end joined to the outer wall 10. The cut-off valve 28 is a valve for removing the air accumulated in the upper part of the fuel tank 1 when the fuel is put into the fuel tank 1. The cutoff valve 28 is made of metal.

The cross-sectional shape of the fusible core used for manufacturing the fuel tank 1 is shown in FIG. This disappearing core 30 is
A low melting point metal having a lower melting point than E (for example, melting points 110 to 1
20 ° C.) as a main component, the sub tank peripheral wall 22, the separator 26 and the cut-off valve 2 as insert parts.
8 is installed (embedded). Such a core 30 can be used, for example, in the mold with insert parts 22, 26, 2
8 can be arranged and molded together with the low melting point metal. Fuel supply hole 12 of core 30
A rod-shaped protrusion 32 is formed at a position corresponding to (see FIG. 1). The surface other than the surface on which the protrusion 32 is formed is relatively smooth. That is, in the present embodiment, the surface of the core 30 on the side where the protrusion 32 is formed corresponds to the uneven surface 34, and the other surface corresponds to the smooth surface 36.

FIG. 3 schematically shows the outline of the manufacturing apparatus used in this embodiment. The fuel tank manufacturing apparatus 2 includes a horizontal extrusion molding device 40, a vertical pressing device 50, and a transfer device 6.
It is configured to include 0. The transfer device 60 is provided with a transfer arm 62 that can move and rotate in the axial direction (front-back direction). The extrusion die 42 of the extrusion molding device 40 is provided with EVOH and HDPE from the raw material supply unit 44.
Is supplied. Further, the extrusion die 42 is provided with an annular extrusion port (not shown). The extrusion device 40 is an EV
A tubular molded body (constituting a cylinder whose cross section is closed) having a three-layered wall surface in which HDPE layers are formed on both sides of the OH layer can be extruded from the extrusion port. The pressing device 50 includes an upper mold 52 and a lower mold 54, and is installed on the extrusion side (extrusion die 42 side) of the extrusion molding device 40. The lower mold 54 is provided with a positioning pin 56 that can project into the mold.

At the time of manufacturing, as shown in FIG. 3, the core 30 is attached to the tip of the transfer arm 62. At this time, the core 30 is oriented so that the smooth surface 36 faces upward and the concave-convex surface 34 (here, the side where the protrusion 32 is formed) faces downward. Then, the transfer arm 62 (and the transfer device 60) holding the core 30 is advanced (to the position shown in FIG. 4) until one end of the core 30 comes into contact with the extrusion die 42. 3 to 9, the illustration of insert parts is omitted and the structure of the core 30 is simplified for the purpose of clarifying the drawings.

With the core 30 abutting in this manner,
As shown in FIG. 4, the resin is extruded around the core 30 from an annular extrusion port provided in the extrusion die 42. At this time, at least on the upper surface (smooth surface 36) of the core 30, the resin may be extruded along the core 30 (using the core 30 as a guide in the longitudinal direction). In this way, the preform 14 having a closed cross section (cylindrical shape) is extruded around the core 30, and the core 30 is arranged in the cylinder of the preform 14. The preformed body 14 extruded from the extrusion die 42 has an upper surface from the side where it is extruded.
It is received by the upper surface of 0 (smooth surface 36). Therefore, the preform 14 is prevented from being deformed by its own weight. At the end of the extrusion molding of the preform 14, it is preferable that the transfer arm 62 be slightly retracted (moved to the left side in FIG. 4) to secure a molding allowance for press molding described later.

As shown in FIG. 5, the extruded preform 14 is cut from the raw material in the extrusion molding device 40, and then the conveying arm 62 is further retracted, whereby the extruded preform 14 is made into a core. Holding position around 30 and press position with this core 30 (between upper die 52 and lower die 54)
Carry to. Meanwhile, the extruded preform 14 is
The temperature is maintained at a temperature at which molding is possible due to residual heat during extrusion. In order to easily maintain (heat-retain) the preform 14 in a temperature range in which it can be molded, the core 30 is appropriately heated (eg, higher than the softening point of HDPE and lower than its melting point) prior to extrusion molding. ) Is preferably preheated. Further, in order to enhance the press moldability of the preform 14, it is preferable to preheat the upper mold 52 and the lower mold 54 to an appropriate temperature range.

As shown in FIG. 6, a positioning pin 56 is projected from the lower mold 54 with respect to the core 30 and the preform 14 arranged at the pressing position. As a result, the positioning pin 56 is inserted into the protrusion 32 of the core 30 through the preform 14. After the core 30 and the preform 14 are thus positioned, the carrier arm 62 (and the carrier device 60) is retracted as shown in FIG. 7 to remove the core 30 from the carrier arm 62.

Then, the core 30 and the preform 14 are pushed into the lower mold 54 as shown in FIG. 8, and the upper mold 52 and the lower mold 54 are combined as shown in FIG. Upper mold 52 and lower mold 5
The preform 14 is press-molded between the ends 4 and 4 to close (seal) the cylinder ends (the left and right ends in FIG. 9) of the preform 14. In this way, as shown in FIG. 10, a resin molded body 70 having the core 30 inside the outer wall 10 formed by the preformed body itself is formed. Further, by this press molding, the insert parts 22, 24, 28 provided on the core 30 are integrally joined to the outer wall 10. After that, the core 30 inside the resin molding 70
Is eliminated to obtain a hollow resin molded product 1 shown in FIG. For example, the core 30 can be eliminated (removed) by heating the core 30 to a temperature equal to or higher than the melting point and causing the core 30 to flow out from the fuel supply hole 12.

Here, as shown in FIG. 10, the pinch-off portion 72 of the outer wall 10 (the upper die 52 and the lower die 5 at the time of press molding) is used.
4) and the core 3 has a recess 3
8 is formed. At the time of press molding shown in FIGS. 8 to 9, the preform 14 enters into the recess 38 and is molded, so that the pinch-off portion 72 has the outer wall 10 at the outside.
Is slightly thicker than other places (typically, about 1.2 to 2 times the average thickness of other places). For example, the average thickness of other parts of the outer wall 10 is 2 to 10
mm (preferably 3 to 7 mm, here 5 mm),
Depending on the average thickness, the wall thickness of the outer wall 10 in the pinch-off portion 72 is 2.4 to 20 mm (preferably 4.5 to 10 mm).
mm, here 7.5 mm) is preferable. This makes it possible to further improve the reliability (typically, gas barrier property, mechanical strength, etc.) of closing the pinch-off portions 72.

As shown in the enlarged view of FIG. 11, the recess 38 has a shape such that the outer wall 10 is formed by entering the outer wall 10 at an angle of approximately 90 ° (typically 75 to 105 °). It is preferably provided. Also, the outer wall 1
The base shape of the portion where 0 enters the depression 38 is substantially arcuate, and the radius r of the arc is about 2 mm or more (typically 2
To 20 mm, preferably 3 to 10 mm). With such a shape, the impact resistance of the obtained hollow resin molded product 1 can be further improved.

The resin hollow molded article obtained by the method of the present embodiment is provided with an outer wall formed by press-molding a preformed body having a closed cross section. It is the cylinder end portion of the preform that is closed (sealed) by press molding, and the peripheral wall portion of the cylinder is substantially seamless. Therefore, as compared with the case where the core covering layer is formed using a flat sheet (see FIG.
8), the seal length of the outer wall (core coating layer) can be clearly shortened. This improves the gas sealability. As a result, without forming another resin layer or the like on the outside of the core coating layer, it is possible to produce a resin hollow molded article having practically sufficient gas sealability by the outer wall formed from the preformed body itself. it can. That is, the manufacturing process of the hollow resin product can be simplified. The resin hollow-molded product may have another resin layer or the like on the outer side of the outer wall (core coating layer), if necessary.

In this embodiment, EVOH was used as the resin constituting the gas barrier layer, but a general high gas barrier resin such as nylon (registered trademark) can be used without particular limitation in the practice of the present invention. . Further, the internal structure of the wall surface of the preformed body is not limited to the layered structure, and for example, a preformed body having a single-layered wall surface mainly composed of EVOH may be used. The material of the fusible core is not limited to the low melting point metal, and for example, a resin having a lower melting point than the constituent material of the preform can be used. Alternatively, the fusible core may be formed using a material such as a polyacetal resin that can be decomposed and vaporized by a chemical reaction under appropriate conditions (for example, nitric acid atmosphere).

In the fusible core 30 used in this embodiment, one of the smooth surfaces 36 faces the uneven surface 34. However, depending on the shape of the hollow resin molded product to be manufactured, the uneven surface 34 may be formed.
The disappearing core 30 having a shape in which the surface opposite to is also an uneven surface
May be used. In such a case, the following manufacturing method can be preferably adopted.

For example, the uneven surface 3 provided with the protruding portion 32
The surface facing 4 is also an uneven surface (an uneven surface 35 shown in FIG. 13), and the surfaces sandwiched between these uneven surfaces (adjacent surfaces) are smooth surfaces (smooth surfaces 36, 37 shown in FIG. 12). In this case, as shown in FIG.
The preform 14 is extruded around the periphery of (in FIG. 12,
The core 30 is arranged so that the concave-convex surface 34 provided with the protrusion 32 faces the front side). Then, as shown in FIG. 13, the transfer arm 62 is rotated around the axis (for example, about 90 ° toward the front side in FIG. 12). As a result, the core 30
The core 30 is set in the press device 50 by changing the direction of the preform 14 held by the core 30 so that the uneven surface 35 and the uneven surface 34 face upward and downward, respectively. By press-molding the preform 14 in this direction, the preform 14 can be easily made to conform to the irregularities of the core 30. That is, the moldability of the preform 14 is improved. Further, by rotating the core 30 and the preform 14 after the preform 14 is extruded, the surface of the core 30 different from that when the preform 14 is extruded faces upward. Since this new surface (here, the uneven surface 35) supports the preform 14 (which is maintained at a temperature at which it can be molded) from the inside, the familiarity between this surface and the preform 14 is improved. This further improves the press formability of the preform 14.

In this embodiment, one end of the sub-tank peripheral wall 22 is closed by the outer wall 10 to form the bottomed cylindrical sub-tank 20, but as shown in FIG. 14, the sub-tank previously molded into a bottomed cylindrical shape. The bottom surface 23 of 21 may be joined to the outer wall 10. In the bottom surface 23, as shown in the drawing, an inversely tapered through hole 25 (reducing the diameter toward the outer wall 10 side) is formed.
Should be provided. With such a shape, a part of the preform 14 is pressed through the through hole 25 during press molding.
You can get inside. By this, the sub tank 21 can be more firmly attached to the outer wall 10.

<Second Embodiment> This second embodiment is an example in which a hollow resin product is manufactured by using a core different from that of the first embodiment. Hereinafter, members having the same functions as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 15 shows a fusible core 30 according to this embodiment.
It is a sectional view showing resin molding 70 obtained using.
As shown in the figure, the fusible core 30 used in this example is
A plurality of hollow-shaped and mainly molded resins having a lower melting point than HDPE (four are shown in FIG. 15)
Sub-cores 30a to 30d. The sub-core 30a is integrally provided with a cutoff valve 28, the sub-core 30c is integrally provided with the sub-tank peripheral wall 22, and the sub-core 30d is integrally provided with a separator 26. Also, the sub core 30
A part of a forms a rod-shaped protrusion 32. The hollow core 30 is configured by combining these sub-cores 30a to 30d. By using the core 30 having such a configuration to perform extrusion molding and press molding of the preform by the same operation as in the first embodiment,
The resin molded body 70 shown in FIG. 15 can be manufactured.
Then, the hollow core 30 is eliminated (for example, heated to a temperature equal to or higher than the melting point to flow out from the fuel supply hole 12) to obtain a resin hollow molded article.

Since the core 30 used in this embodiment has a hollow shape, it is possible to reduce the amount of the core forming material (mainly resin here) used as compared with the solid core. This makes it easier to remove the core 30 from the resin molded body 70. For example, the energy and / or time required to melt the core 30 can be reduced. Moreover, since the core 30 can be made lighter than that of the solid shape, the core transport facility can be downsized. The hollow core 30 is divided into a plurality of sub-cores 30a to 30d. The individual sub-cores 30a to 30d are easier to mold than the hollow shape, and the insert parts 22, 26, 28 can be installed easily.
Therefore, the core 30 can be easily configured by assembling these sub-cores 30a to 30d. In addition, as compared with the entire core 30, the sub-cores 30a to 3a
Since each of 0d is small and lightweight, it can be easily molded and transported.

As a modification of the second embodiment, a through hole that allows the hollow portion to communicate with the outside is formed in a part of the hollow core 30, and a plug for opening and closing the through hole is provided. A core 30 having a different shape can be used. For example,
The protrusion 32 shown in FIG. 15 is a plug member 33 that can be attached to and detached from the sub-core 30a as shown in FIG. According to the core 30, the fluid can be supplied to the hollow portion L or discharged at an arbitrary timing through the opening (through hole) formed by removing the plug member 33. . An example of a suitable manufacturing method using the core 30 having such a configuration will be described below.

That is, high temperature oil is filled into the hollow portion L of the core 30 through the opening formed by removing the plug member 33, and the plug member 33 is attached to the opening to cover the lid. This preheats the core 30. Around the preheated core 30,
The preform is extruded as in the first embodiment, and the preform is conveyed together with the core 30 and set in the pressing device. Since the core 30 has good heat retention due to the oil filled inside (hollow portion L), the extrudability of the preform extruded around the core 30 is good. Further, the cooling rate of the preform can be slowed down by the heat stored in the core 30. That is, it is easy to maintain this preform in the temperature range in which it can be formed.

After the press molding, the plug member 33 is removed, and the oil filled in the hollow portion L is discharged from the opening, whereby the cooling rate of the resin molded body 70 (particularly the outer wall 10) can be increased. Further, the cooling of the outer wall 10 can be further promoted by supplying (filling, circulating, etc.) a cooling fluid (oil at low temperature, air at room temperature, etc.) to the hollow portion L from this opening. When the resin molded body 70 has cooled sufficiently, it is taken out of the mold, and hot oil (having a temperature higher than the melting point of the main constituent material of the core 30) is supplied to the hollow portion L through the opening. Thereby, the core 30 is melted and discharged together with the oil from the opening. In this way, as the manufacturing process progresses, fluid (oil, etc.) enters and leaves the hollow part of the core,
It is possible to accelerate the temperature change (heating or cooling) of the fusible core and / or the preform. This can shorten the time required to manufacture the hollow resin molded product.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. Further, the technical elements described in the present specification or the drawings are
The technical usefulness is exhibited alone or in various combinations, and is not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings achieves a plurality of purposes at the same time, and achieving the one purpose among them has technical utility.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a resin hollow molding product according to a first embodiment.

FIG. 2 is a cross-sectional view showing a fusible core according to the first embodiment.

FIG. 3 is a schematic diagram showing a stage in which a fusible core is attached to a transfer arm.

FIG. 4 is a schematic diagram showing a step of extruding a preform around a fusible core.

FIG. 5 is a schematic diagram showing a stage in which a preform is conveyed to a press position.

FIG. 6 is a schematic view showing a step of setting a preformed body in a pressing device.

FIG. 7 is a schematic diagram showing a step of setting a preformed body in a pressing device.

FIG. 8 is a schematic diagram showing a step of press-molding a preform.

FIG. 9 is a schematic view showing a step of press-molding a preform.

FIG. 10 is a cross-sectional view showing a resin molded body according to the first embodiment.

11 is an enlarged cross-sectional view showing a portion XI of FIG.

FIG. 12 is a schematic view showing a step of extrusion molding a preform around the fusible core, which is a modification of the first embodiment.

FIG. 13 is a schematic view showing a modified example of the first embodiment and showing a step of press-molding a preform.

FIG. 14 is a cross-sectional view showing a resin hollow molded article according to another modification of the first embodiment.

FIG. 15 is a cross-sectional view showing a resin molded body according to a second embodiment.

FIG. 16 is a sectional view showing a resin molded body according to a modified example of the second embodiment.

FIG. 17 is a schematic perspective view showing an example of a method of wrapping the fusible core with a sheet, and showing a step of disposing the sheets above and below the fusible core.

FIG. 18 is a schematic perspective view showing an example of a method of wrapping the fusible core in a sheet and showing a stage in which upper and lower sheets are fused.

[Explanation of symbols]

1: Fuel tank (hollow resin molding) 10: Outer wall (core clothing layer) 14: Preform 22: Sub tank peripheral wall (insert part) 26: Separator (insert part) 28: Cut-off valve (insert part) 30: Vanishing core 34, 35: uneven surface 36, 37: smooth surface 38: hollow 40: Extrusion molding device 42: Extrusion die 50: Press machine 52: Upper mold 54: Lower mold 70: Resin molded product 72: Pinch off section

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F202 AD05 AG05 AG07 AG26 AG27                       CA17 CB01 CB12 CK81 CL02                       CM29 CQ01 CQ05 CQ10                 4F208 AD05 AG05 AG07 AG25 AG27                       MA05 MB01 MB11 MB29 MC03                       MG02 MG22 MJ05 MJ09 MK15                       MW02 MW31 MW45

Claims (6)

[Claims] 1. A step of extrusion-molding a resin-made preform which constitutes a cylinder having a closed cross-section, and the preform after the extrusion-molding while the preform is maintained at a temperature at which it can be formed. The process of disposing the fusible core in the cylinder, the step of setting the preformed body in which the fusible core is installed and maintained at the temperature at which it can be molded in the press machine, and using the press machine A step of closing the tube end of the preformed body, forming a resin molded body having a fusible core inside the outer wall formed from the preformed body, and a step of eliminating the fusible core from the resin molded body A method for producing a resin hollow molded article including: 2. The method for producing a resin hollow molded article according to claim 1, wherein the extrusion molding of the preform is performed sideways. 3. The extrusion molding of the preform and the cylinder of the preform by extruding the resin in a tubular shape around the fusible core using the fusible core as a longitudinal guide. The method for producing a hollow resin molded article according to claim 2, wherein a fusible core is provided inside. 4. The fusible core has an uneven surface and a smooth surface, and after extrusion molding of a preform around the fusible core arranged so that the smooth surface faces upward, the uneven surface is formed. The method for producing a resin hollow molded article according to claim 3, wherein the preform is press-formed by disposing the fusible core so that the surface thereof faces up or down. 5. The resin hollow-molded article according to claim 2, wherein the extruded pre-molded article is conveyed to the press-molding position while being held by the fusible core arranged in the cylinder. Production method. 6. The method for producing a resin hollow molded article according to claim 1, wherein an insert component is installed in advance on the fusible core arranged in the cylinder of the preform. .