JPH07276479A - Synthetic resin hollow molded product and production thereof - Google Patents

Abstract

PURPOSE:To simply form a rib to the inner surface of a synthetic resin hollow molded product, especially, a panel-shaped hollow molded product indefinite in thickness. CONSTITUTION:An insert material 3 becoming the core of a rib is attached to the inner wall surface of a mold for hollow molding in a detachable manner to perform hollow molding and the insert material is covered with a parison to produce a hollow molded product 1 having a rib 4. At the time of the detachment of the molded product from the mold, the insert material is separated from the mold to be contained in the molded product as the core of the rib 4. Therefore, the rib 4 can be easily formed even to a panel-shaped hollow molded product indefinite in thickness and the height of the rib 4 can be arbitrarily selected and, further, the rib can be attached even to the hollow molded product 1 having a skin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded product having a rib inside a hollow molded product and a method for producing the same. By using an insert material as a core of the rib, the molded product is wholly or partially molded. The present invention relates to a molded product which is easy to mold even a molded product having a variable thickness and a method for producing the molded product.

[0002]

2. Description of the Related Art Hollow molded products, for example, panel-shaped hollow molded products, are used as core materials for automobile seat backs, floor boards in trunk rooms, strength members such as pallets, partition boards for houses, walls of simple houses and the like. When molding such a panel-shaped molded product by blow molding, a method of forming ribs is used to improve strength. The most commonly used method for forming ribs is compression from one side of the molded product as shown in FIG. In addition, Japanese Patent Publication No. 2-16209 proposes another method of attaching ribs (partition plates) inside the hollow molded product. In this method, before inserting the synthetic resin parison into the blow mold and tightening the mold, the sliding plates arranged on one side or both sides of the blow mold are advanced to move the parison wall surface forward or simultaneously. This is a method in which, after partial pressure bonding, the tip of the sliding plate is retracted to the mold surface and air blow is performed to form ribs inside the molded product.

[0003]

In the compression method, ribs can be easily formed, but one side is a flat surface, but the other side is uneven, so when using both sides such as a partition plate, unevenness is obtained. In some cases, the shape may adversely affect the appearance. Further, this compression type rib has a problem that when a load is applied, an opening occurs between the rib and a valley (recess) of the rib, and the effect of the rib cannot be fully utilized. By using the method of Japanese Patent Publication No. 2-16209, unlike the case of a compression type rib, the rib effect on strength due to the opening of the recess does not decrease and a stronger product can be obtained in terms of strength as compared with the compression type rib. You can

However, this method has a problem in that it cannot be applied to a molded product in which the product thickness changes in a part or the whole of the product in terms of accuracy in manufacturing a die and a sliding plate sliding method. Since the product thickness changes, the length of each sliding plate changes. When each sliding plate is operated with one cylinder (air pressure, hydraulic pressure), the stroke becomes constant. Therefore, when each sliding plate is retracted after partially crimping the parison, The tips are uneven on the die surface, resulting in irregularities. In order to avoid this, an operating cylinder is required for each sliding plate, which increases costs and is not realistic. By solving these problems, it is possible to form ribs inside even a molded product in which the product thickness varies in a part or the whole of the product, that is, a product in which both surfaces of the product do not have parallel surfaces. Is the purpose of.

[0005]

Means for Solving the Problems The present invention has been achieved as a result of earnest research for solving these problems, and is characterized by using an insert material as a core and coating the outside of the core with the material of the hollow molded article. And the ribs are configured, and the manufacturing method is to set the insert material in advance on the inner wall surface of the mold,
After blow molding, the molded product is removed from the mold while the insert material is contained in the rib.

That is, the present invention is a hollow molded product having a rib on the inner surface of a synthetic resin hollow molded product, the rib having an insert material as a core material, and the outside of the rib being covered with the material of the hollow molded product. The manufacturing method is such that the insert material is detachably preliminarily attached to the inner wall of the hollow mold of synthetic resin, and the hollow molding is performed, and the insert material is used as the core material on the inner surface of the hollow molded product, and the outside is covered with synthetic resin And removing the hollow molded product in which the core material is included in the rib from the mold.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view and a sectional view taken along the line AA of a panel-shaped hollow molded article having a non-uniform thickness, which is one of the present invention. FIG. 2 is a partial state view showing an insert material serving as a core of a rib and a state where the insert material is attached to a mold. The hollow molded article 1 has a hollow portion 2 formed therein, and the hollow portion is normally communicated with the end of the molded article. Reference numeral 3 denotes an insert material, the outer side of which is coated with a resin to form a rib 4. The illustrated rib 4 is a plate-shaped body extending in one direction of the molded product.

As the synthetic resin which is a hollow molded product, usual resins such as polyethylene and polypropylene can be used. In the present invention, the hollow molded product is most suitable when it is in the form of a panel, but it is also applicable to other molded products. It is a feature of the present invention that ribs can be easily formed even in the case of a panel-shaped molded product having a non-uniform thickness. The insert material is not limited to the same type of material as the hollow molded product,
Other resins and metals other than resins and other materials can also be used.
Further, the resin may be reinforced with an inorganic filler, glass fiber or the like. Among these, if the insert material is of the same type as the material of the hollow product, the insert material and the parison will be welded during the hollow molding, and strong ribs will be formed, which is not only desirable, but also convenient for product recycling. Is.

The shape of the insert material is determined according to the shape of the ribs, but it is not limited to the plate shape and may be a column shape. If it is a columnar insert material, columnar ribs are formed. When the hollow material is molded from the parison, the insert material is wrapped in the parison to be in a state as shown in FIG. The rib 4 has a structure in which the opposing inner surfaces of the hollow plate are bridged (connected) in FIG. 1, but the height of the rib is reduced so that the tip of the rib is located in the hollow without bridging. It is also possible to do so. This is not possible with the conventional sliding plate method. This rib can be provided on both sides of the hollow plate. In the case of plate-shaped ribs, the ribs in FIG. 1 are arranged in the same direction, but the ribs can be partially changed in direction.

Further, although the conventional compression system and sliding plate system could not adhere the skin such as the nonwoven fabric on both sides of the product at the time of molding, the use of this system enabled both sides to be bonded. When performing double-sided bonding, attach an insert plate on the surface skin (one side and both sides) to be bonded, set it in the mold, and perform normal molding below to obtain ribs on the inner surface It is possible to obtain a molded product excellent in strength, which is obtained by sticking a skin on the surface.

Next, the invention of the manufacturing method will be described. Figure 2
The state where the insert material 3 is attached to the inner wall surface of the mold 7 is shown in FIG. First, the pin 5 is fixed to the inner wall surface ((a) of FIG. 2).
A pin insertion hole 6 is provided in the insert material ((b) of FIG. 2). A pin is passed through the insertion hole to attach the insert material to the mold ((c) of FIG. 2). The parison is extruded into this mold, the mold is clamped, and air is blown into the mold to perform hollow molding. Depending on the height of the insert material, ribs such as those shown in FIG. 1 bridging the inner surfaces of the facing plates or not shown, but ribs with a low height may be provided on the ridges from one or both of the facing plates. it can. If the product after molding is removed from the mold, the insert material easily comes off from the pin and becomes the core of the rib 4.

[0012]

EXAMPLE The shape of the product used in the present invention is shown in FIG. The product is a panel-shaped hollow product, which is a curved product with a non-uniform product thickness. Polypropylene (MFR 0.3 g / 10 min) was used for the molded product body. As the insert plate used for the rib part, the same polypropylene as that of the product body and a sheet (thickness 1.5 mm) made by using a T-die with polypropylene filled with 25 wt% of talc, which is an inorganic filling material, to an appropriate size What was cut out was used. A cross section of a product molded using this insert plate is shown in FIG. The size of the product is 500 mm x 700 mm, the thickness is 60 mm at both ends,
The central portion is 20 mm. The rib length is the product length 70
It is 500 mm in the direction of 0 mm. As can be seen from the cut surface, it can be seen that ribs are formed on the inner surface of the product. The insert plate at the rib and the product body were welded together.

[0013]

INDUSTRIAL APPLICABILITY By using the present invention, it is possible to easily attach an internal rib to a hollow molded product, and especially to a panel-shaped hollow molded product in which the thickness of the product is not constant. Further, the ribs may have various shapes such as bridging between the opposing plates, or ribs formed on the inner surface. In this way, the strength of the product can be easily improved.

[Brief description of drawings]

FIG. 1A is a perspective view of a panel-shaped hollow product of the present invention and FIG.

FIG. 2 is a partial state view showing a method of attaching an insert material to a mold according to the present invention.

FIG. 3 is a perspective view (a) and a BB cross-sectional view (b) of a panel-shaped hollow product according to a conventional compression method.

[Explanation of symbols]

 1 Panel Hollow Molded Product 2 Hollow Part 3 Insert Material 4 Rib 5 Pin 6 Pin Insertion Hole 7 Mold Inner Wall

Claims (6)

[Claims] 1. A synthetic resin hollow molded article having a rib on an inner surface of the synthetic resin hollow molded article, wherein the rib has an insert material as a core material and an outer side thereof is covered with the material of the hollow molded article. Molding. 2. The synthetic resin hollow molded article according to claim 1, wherein the hollow molded article has a panel shape. 3. The synthetic resin hollow molded article according to claim 1, wherein the hollow molded article has a panel shape in which the thickness is not constant. 4. The synthetic resin hollow molded article according to claim 1, wherein the rib bridges between opposing plates on the inner surface of the hollow molded article. 5. The synthetic resin hollow molded article according to claim 1, wherein the insert material is the same material as the hollow molded article. 6. An insert material is detachably preliminarily attached to an inner wall of a synthetic resin hollow molding die to perform hollow molding, and the insert material is used as a core material on the inner surface of the hollow molded article, and the outside thereof is made of synthetic resin. A method for producing a synthetic resin hollow molded article, which comprises forming a covered rib and removing the hollow molded article in which the core material is included in the rib from a mold.