JP2002210809A - Hollow resin molding and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow resin molding having excellent appearance and strength and a method for manufacturing the same. SOLUTION: The method for manufacturing hollow resin molding comprises the steps of protruding a core member so as to form a rib contacted from one mold toward an inner surface of the hollow part of the other side, and blow molding the hollow resin molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molded resin hollow body and a method for blow molding a resin molded body.

[0002]

2. Description of the Related Art There is known a method of manufacturing a hollow molded article by sandwiching a cylindrical parison with a mold and blowing air into the parison.

[0003] In order to manufacture a flat, lightweight resin panel, a large projection is made using a molding machine having a mold clamping force sufficient to make the inside hollow and lightweight and to withstand a blowing pressure of 10 kgf / cm ² or more. The above method is preferable in that an article having an area can be formed. However, a flat hollow article has a problem in that the opposing flat plate portions are easily bent and dented, and it is difficult to obtain rigidity.

Japanese Patent Application Laid-Open No. Hei 9-193656 describes a method of integrally forming a reinforcing rib to improve the rigidity of the hollow flat plate. According to this publication, the vertical plate material (8a) is advanced and retracted from both sides of the cavity,
The reinforcing rib is formed without forming a concave surface.

[0005]

However, in this molding method, since a vertical plate is pressed into the parison from both sides of the cavity, a hollow body having a preferable design surface in which the surface of the molded product is decorated with a cloth interposed therebetween is used. Cannot be molded in one step. Also, even when the cloth is not pasted, the dividing line between the vertical plate and the surrounding general cavity surface is transferred to the design surface of the molded product on the mold cavity surface, so that the appearance is impaired. is there. In this case, when a texture is provided on the design surface, the texture pattern becomes discontinuous. In addition, there is also a problem that as a result of the local advance and retreat of the molten resin, a difference in gloss from the peripheral portion occurs. Therefore, it has been difficult to produce a hollow molded article having a good appearance by applying the above-mentioned conventional technology. Further, the structure of the reinforcing ribs described above does not sufficiently improve the rigidity, and is not satisfactory, for example, for floor boards or the like that require higher strength.

An object of the present invention is to provide a hollow molded article which solves the above-mentioned conventional problems and a method for producing the same.

[0007]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the above-mentioned problems, and as a result, has found that it is effective to provide specific ribs on a pair of opposing surfaces.
The present invention has been reached.

That is, the present invention provides (1) a resin molded article having a hollow portion closed inside a pair of opposing surface portions and a side edge portion surrounding the pair, and an inner surface of one side of the pair of surface portions. A first rib extending in the hollow portion so as to extend substantially between the edges toward the surface portion on the other side, and at least a portion of the first rib is formed.
The resin molded body has a second rib abutting on the other surface portion, (2) closed inside a pair of opposed surface portions and a side edge portion surrounding the pair. A resin molded body having a hollow portion, wherein a first rib is formed on an inner surface on one side of the pair of surface portions so as to extend the hollow portion toward a surface portion on the other side substantially between edges, and A third rib is formed on the other inner surface of the surface portion toward the one surface portion, and at least a part of the first rib is in contact with the third rib. (3) The resin molded article according to (2), wherein at least a part of the first rib has a second rib abutting on the third rib. The resin molded article according to any one of (1) to (3), wherein the rib has an opposed side wall.
(5) The above (1) to (5) having a rib on the inner surface of the side edge portion.
(6) A method for producing a resin molded body having a hollow portion closed inside a pair of opposing surface portions, wherein the resin molded body according to any one of (4) and (4) is a cylindrical shape having a bead on an inner peripheral surface. The preformed body is extruded, the preformed body is housed in a mold cavity, and a pair of opposing surfaces on one side and the other side and a hollow space between them are formed from one side to the other side. While forming a rib extending to the surface portion, the rib is brought into contact with the other surface portion via the bead, and a fluid passage is formed between the rib and the other surface portion, and the inside is pressurized with fluid. And a method for producing a resin molded body, wherein a surface portion is press-formed on a cavity surface.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the hollow portion of a resin molded article of the present invention, a rib is formed from one surface to another surface.
A mold surface having an integral cavity surface is transferred to the other surface portion, and no trace of a vertical plate material or the like protruding from the cavity surface toward the parison is generated. This is because, on the other side surface portion suitable as a design surface, there is no violent movement such as the parison being stretched and collapsed and restored again, so that the color tone and gloss change due to local movement in the resin shaping process are reduced. It does not occur and results in a uniform or continuous change appearance. According to such a mold, woven fabric, non-woven fabric,
It is also easy to integrally attach a resin sheet or the like provided with a grain pattern or the like.

[0010] The first rib may be a fixed core member erected at a predetermined height in the cavity, or may be a member that can come and go with a predetermined stroke. For the predetermined stroke, the core member for forming the first rib may be retracted so as to be flush with the cavity surface of the mold (flash surface), or may be retracted so as to project from the cavity surface. May be. Further, it can be in a state further retreated than the cavity surface. In this case, a portion protruding outward on one side is formed, and this is useful as a leg integrally reinforced with the rib.

At least some of the first ribs must be in contact with the other surface. It is important that at least a part of the first rib is in contact with the surface on the other side via a bead (a second rib and / or a third rib) integrally formed during the extrusion of the parison. If the first rib is not in contact with the other side portion via the bead (the second rib and / or the third rib), the other side portion is not supported by the first rib, so that the rigidity of the hollow molded body is increased. Is not obtained, and the surface is lowered when pressed. Also, when the core member is retracted, the first rib cannot move because the distal end shape of the first rib is in a molten state in the molding process, so that a predetermined shape cannot be obtained.

The bead may be on one side, on the other side, on both sides, or in addition, inside the side edges surrounding the surface. When it is on one side, the first rib is reinforced and a projection is formed on at least a part of the tip of the rib, so that the projection (second rib) abuts on the other side. Fluid passages are formed because portions without protrusions do not come into contact with the surface on the other side. Fluid pressure can be applied to all portions by blowing from a small portion, for example, one portion during blow molding. Therefore, the fluid pressure is uniformly applied throughout. Further, since a plurality of blow nozzles (blow pins) are not required, a complicated mechanism is not required, which is preferable in terms of equipment cost.

[0013] The beads may be formed on the other side. In this case, the rigidity of the other side, which is usually used as a design surface, can be increased. In addition, a fluid passage is formed in a place other than the bead so that the opposing surfaces are not in contact with each other. Therefore, the same operation as the one side is provided. Further, the other side can be formed into a flat shape by simple resin behavior even in blow molding not using a core member. Therefore,
There is little bead stretching and the reinforcing effect is maintained.

Further, when beads are formed on both sides,
Basically, it is more preferable because these effects are expressed additively. The bead may further be formed on an inner surface of a peripheral portion surrounding the pair of surface portions. In this case, the periphery can be reinforced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described. Figure 1
1 shows a rear interior of the vehicle V. A floor board 1, which is an interior panel of an automobile, forms a floor surface F of a luggage space L by combining front and rear boards 2, 3, and a spare tire S is provided below the floor surface. And a recess for accommodating the tool T and the like. The insulator 4 is fitted in the concave portion, and has an upper surface portion 4a parallel to the floor surface F except for a portion for accommodating the spare tire S and the tool T. The insulator 4 is formed by foaming polypropylene beads in a mold.

FIG. 2 shows part A of the front board 2 of FIG.
As shown in FIG. 1, the rear board 3 has a slightly different shape such as an arched edge and a lifting hook, but basically employs the same structure as the board 2.

In FIG. 2, the front board 2 has a lower surface 22 facing upward, a peripheral portion 24 is formed in a frame shape, and grid-like ribs 23, 28 are provided on almost the entire lower surface 22. It is formed over. That is, it is formed as a lattice-shaped groove and protrudes toward the upper surface 21.

A bead 25 is formed along the longitudinal side edge 24a of the front board 2. The plate thickness of the upper and lower surfaces 21 and 22 is approximately 2.0 mm, and the height of the bead 25 is approximately 0.2 mm.
8 mm, the front board 2 is a hollow molded article made of polypropylene resin, ABS resin, modified PPO resin, etc.
And a belt-like projection 21a is provided thereon to provide a design surface.

Next, a molding method will be described. FIG. 3 shows a head portion 10 of a blow molding machine. FIG. 3A shows a die 11 and a nozzle 12 for discharging molten resin sent from an accumulator of a screw type extruder (not shown) into a cylindrical shape. The nozzle 12 is lowered to open the ring-shaped discharge port 14. Edge 1 of nozzle 12
5, a notch 16 having a cylindrical surface is formed over the entire circumference at a predetermined interval. The resin sent from the accumulator forms a cylindrical parison P having a cross-sectional shape following the opening shape of the discharge port 14 as shown in FIG. That is, a bead B that is continuous in the up-down direction is formed at a position corresponding to the notch 16 on the inner peripheral surface.

The parison P has a thickness of 2.5 to 4 mm,
In the embodiment, the height of the beads B is 3.0 to 1.0 mm.
8 mm and 1.5 mm in the embodiment.

FIG. 4 is an explanatory cross-sectional view of the mold as viewed from above. As shown in cross section in FIG.
0 cavities 31c, 32c of a pair of molds 31, 32
Drop parison P in between. A core member 33 is formed in the cavity 31c toward the cavity 32c of the mold 32. For ease of explanation, only the core member 33 formed in the horizontal direction is shown, and the core member in the vertical direction is omitted. Before the mold 30 comes into contact with the parison P, the terminal below the parison P is pinched and crushed flat by a usual method, and the opening is closed. A blow pin, which can be advanced in the direction of arrow D1 (not shown), is provided on the mold 31 side.
The so-called pre-blow is performed to slightly increase the internal pressure of the air conditioner.

The molds 31 and 32 are moved around the parison P in the directions D1 and D2, respectively, and the mold 30 is closed.

FIG. 5 is an explanatory cross-sectional view of the die when the core member 33 abuts against the parison after the start of closing the die.

As shown in FIG. 5, the core member 33 hits the side wall of the parison P during the mold closing process and is indented inside, and the bead B is stretched in a corrugated manner along the core member 33. The parison P is swung in the D1 direction by the core member 33 and pressed against the inner surface of the cavity 32c of the mold 32. The parison P first comes into contact at the center of the core member 33 and the cavity 32c, and then contacts the terminal in order, and at the same time when the mold 30 is completely closed, the blow pressure is increased.
Air of gf / cm ² is blown, and the parison P is pressed against the surfaces of the cavities 31c and 32c to form a hollow shape (FIG. 6). FIG. 6 shows a case where the beads 25 face each other for explanation. A bead 25 is formed on the inner surface, and this bead 25 is
5 and is welded to increase the strength of the front board 2.
That is, it is possible to eliminate the sticking of the floor surface F. The tip of the rib 23 between the beads 25 is located on the upper surface 21.
, The ribs 23 do not form a further closed space inside, and the front board 2 forms a single space while the interior is structurally partitioned and reinforced, while the ribs 23 form a single space. By blowing from one place in the space, molding can be performed by applying air pressure to the whole. Therefore, it is only necessary to blow from a single blow pin, and no complicated device is required. Further, assuming that the front board 2 is to be washed with water, it is only necessary to seal only one location, that is, the location where the blow pin has been inserted. Therefore, usability can be easily improved as a floor board for a luggage floor. As described above, in FIG. 4, the core member 33 for forming the rib 23 is illustrated only in the lateral direction for explanation. However, in this embodiment, as shown in FIG. 2, the core members 33 are arranged vertically and horizontally, so that the behavior of the beads B in the molding process is more complicated. That is, in addition to the horizontal core member 33, the vertical core member may be recessed into the parison P, and the position may be a position corresponding to the center of the bead B, or may be located on the left inclined surface of the bead B. In some cases, and conversely, it may be located on the right inclined surface. Therefore, when the lattice-shaped core member is pressed against one surface of the parison P on which the beads B are formed, the relative positional relationship between the core member and the beads 25 is not uniform.

For example, at the tips of the ribs 23 and 28, there is almost no relative movement (shift) with respect to the core member 33. Therefore, when the bead is located at the tips of the ribs 23 and 28, the height of the bead is high. Is maintained. When the core member in the vertical direction extends on the inclined surface of the bead, it acts so as to compensate for the thickness of the rib 23. Therefore, the ribs 23 formed by the vertical core members are arranged so that the fluid blown from the blow pins flows over the entire hollow portion except when the opposing beads contact each other as shown in FIG. 2C. A gap 26 is provided between the gap 21 and the gap 21. Then, the size of the gap 26 can be set to a size slightly smaller than the size of the two beads B. The front board 2 is completed by cutting off burrs 27 on the outer periphery of the molded body with a cutter.

In the above embodiment, the nozzle 1
2, a notch 16 was formed on the entire circumference.
The notch 16 does not necessarily need to be provided on the entire circumference.

For example, it may be provided only at a position corresponding to the upper surface 21 side of the front board 2, may be provided only at a position corresponding to the lower surface 22 side, and , 22 can provide the effect even if it is provided so as to form a bead 25 at a part of the width.

FIG. 7 shows another embodiment. The preformed skin 29 is placed in the cavity 32c of the mold 32, and is integrally blow-molded. The outer skin is made of a jersey fabric backed with a nonwoven fabric of polypropylene resin, and is preliminarily shaped according to the shape of the cavity 32c by vacuum forming.

The molding process is the same as in the previous embodiment.
After being integrally molded, with the burr, the surplus portion 29a of the skin 29
Is cut off to complete the molding.

As described above, since one side is a simple flat surface, it is easy to integrally form the decorative material in combination, and the appearance can be improved.

FIG. 8 shows still another embodiment. FIG.
FIG. 3 is an explanatory longitudinal sectional view of a mold 40.

A driving mechanism (not shown) is connected to the core member 43. When the mold 40 is opened, the core member 43 is opened.
Is stopped at the forward end of the mold 41. Therefore, molding is performed in the same step as the first half of the molding step in the molding die 30.
This embodiment is characterized in that the core member 43 is retracted immediately after the mold 40 is closed. As shown in FIG. 9A, when the core member 43 is retracted so that the tip thereof coincides with the surface of the cavity 41c of the mold 41, as shown in FIG. In a state where the core member 43 is protruded from the
In some cases, as shown in FIG. 9C, the core member 43 may be further retracted from the surface of the cavity 41c.

In the rib 53, the portion where the core member 43 does not exist is crushed by the blow pressure and becomes solid.
FIG. 9 (d) shows a state in which the rib 53 is blown without hitting the opposing parison, and the rib after the core member 43 comes off hangs down by its own weight, or is blown by the blow air, and the position is not determined. Has no effect.

The above ribs 53 are applied to the beads 55,
The ribs 53 are positioned and connected at the locations where the beads 55 are present, and the other locations are the gaps 26 to which the blow pressure is applied, so that the entirety can be expanded by blowing from one blow point.

[0035]

As described above, according to the present invention,
A light-weight, high-strength resin hollow molded article having a good appearance can be obtained, and such a resin hollow molded article can be manufactured by a simple process.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a floor board of an automobile interior panel.

FIG. 2, showing an embodiment of the present invention, is a partial cross-sectional explanatory view of a floorboard.

FIG. 3 is an explanatory view of a method of forming a preform (parison) used in the manufacturing method of the present invention, wherein (a) is an explanatory view of a forming die and a nozzle, and (b) is an explanatory view of (a). Explanatory drawing of a parison with a bead extruded from a die and a nozzle.

FIG. 4 is an explanatory view of an embodiment of the present invention by blow molding, and is a cross-sectional explanatory view of a state in which a mold is filled with a preform (parison) as viewed from above the mold.

FIG. 5 is an explanatory view of an embodiment of the present invention by blow molding, and is a cross-sectional explanatory view of a mold for explaining a state in which a core member 33 abuts against a parison after the mold closing is started.

FIG. 6 is an explanatory view of an embodiment of the present invention by blow molding, and FIG. 6 (c) is a cross-sectional view of a mold for explaining a state of blow molding after closing the mold.

FIG. 7 is an explanatory cross-sectional view of a mold for explaining another embodiment of the present invention.

FIG. 8 is an explanatory longitudinal sectional view of a mold for explaining still another embodiment of the present invention.

FIG. 9 is a view for explaining a mode of retreat of the core member 43;
(A) is when the tip coincides with the cavity surface, (b)
Is to protrude from the cavity surface, (c) is to further retreat from the cavity surface, (d) is the rib 53
FIG. 4 is a vertical cross-sectional view of a mold for explaining a case where blow molding is performed in a state in which the sheet is not brought into contact with an opposing parison.

Claims (6)

[Claims] 1. A resin molded body having a hollow portion closed inside a pair of opposed face portions and a side edge portion surrounding the pair of face portions, wherein one side inner face of the pair of face portions has a substantially A first rib extending in the hollow portion toward the other surface portion, and at least a portion of the first rib has a second rib abutting on the other surface portion. Characterized resin molded product. 2. A resin molded body having a hollow portion closed inside a pair of opposed face portions and a side edge portion surrounding the pair of face portions, wherein one side inner surface of the pair of face portions has a substantially A first rib extending toward the other surface portion is formed in the hollow portion, and a third rib is formed on the other inner surface of the pair of surface portions toward the one surface portion, and at least a part thereof is formed. Wherein said first rib is in contact with said third rib. 3. The resin molded product according to claim 2, wherein at least a part of the first rib has a second rib abutting on the third rib. 4. The resin molded product according to claim 1, wherein the first rib has opposed side walls. 5. The resin molded product according to claim 1, wherein a rib is provided on an inner surface of the side edge portion. 6. A method for producing a resin molded body having a hollow portion closed inside a pair of opposing surface portions and a side edge portion surrounding the pair of surface portions, the cylindrical preforming having a bead on an inner peripheral surface. The body is extruded, the preformed body is housed in a mold cavity, and a pair of opposing one-side surface portions and the other-side surface portion and a hollow interior therebetween extend from one side surface portion to the other side surface portion. While forming the rib, the rib is brought into contact with the other surface portion via the bead, and a fluid passage is formed between the rib and the other surface portion. A method for producing a resin molded body, comprising press-forming the cavity surface.