JPH11309773A - Blow mold and molding method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reuse a burr portion without pre-forming by a method wherein projected outside mating surfaces are provided and, at the same time, space parts are provided. SOLUTION: A pre-blowing is performed in a parison and then molds are clamped together and, at the same time, a blowing pressure is applied both in space parts P and in the parison. In this case, the blow air pressure in the space part P may well be lower than the blowing pressure. On the other hand, the air interposing between the parison and a skin material T and a mold cavity surface is naturally exhausted or forcibly sucked with a suction fan or a vacuum pump through vent holes provided on the mold. Thus, the surface properties are improved. After the completion of cooling is confirmed, a molding is taken out. By taking out of the molding obtained by performing a near conventional laminating blow molding, the resin at burr portion is pressed against a mold surface by means of air or/and needle-like projections S, resulting in cooling and solidifying under the condition being held at the state separated from the skin material T, no bonding with the skin material is present.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for lamination blow molding and a molding method therefor.

[0002]

2. Description of the Related Art In blow molding for producing a hollow resin molded product from a parison injected or extruded into a cylindrical shape from a die head, a parison is injected or extruded from a die head and pre-blown into a bag-shaped parison by a parison pinch. To slightly inflate, put in an open mold, close the mold, and evacuate the gas in the space formed by the mold cavity surface and the parison.From the small air vent hole that leads to the mold surface After suctioning air through a vacuum pump device, high-pressure air is blown into the parison to form the parison into a predetermined shape based on the cavity, and then cooled with a mold to complete the molding. The resin molded article thus molded is taken out by opening the mold.

[0003] A blow mold in which a resin sheet or the like is interposed between a parison discharged by using such a blow molding machine and a mold cavity, the mold is clamped, and the resin sheet is bonded to the surface. Producing molded articles has been practiced conventionally. In the blow molding, burrs (unnecessary portions outside the molded product) are inevitably generated at the outer peripheral portion of the molded product due to the manufacturing method. In ordinary blow molding, there is no skin material but only a base resin, and this burr is collected, cut and crushed, mixed with a new resin, and reused for molding.

[0004]

However, in lamination blow molding, the skin material and the parison must be sufficiently adhered to each other in the product part. It often happens. When the burr portion is reused in such a state, the skin material is intimately mixed with the base resin (material resin of the parison) because the skin material and the parison are in close contact with each other. If the material of the skin material is different from that of the base resin, the physical properties of the molded product will deteriorate and the surface properties will deteriorate. As a result, the parison became contaminated and the molding machine itself became a problem. As a countermeasure, there is a method of preventing the skin material from protruding into a portion corresponding to the burr of the parison. For this purpose, an extra portion of the skin material is eliminated by preforming the skin material prior to the formation of the barison and by making the skin material conform to the shape of the molded product. Although this method is generally performed for deep blow-molded articles, as described above, a pre-molding step is required, and the productivity is reduced. In addition, it is difficult to produce products with excellent surface properties without wrinkles without technically pre-molding deep blow-molded products. Has been done without problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is mainly directed to a shallow blow-molded product, in which a burr portion of a parison (an unnecessary portion outside the molded product: remaining material) is re-used. It is for use without pre-molding. If you remove the extra part of the skin material without preforming the skin material, you can not fix the skin material to the mold,
Wrinkling cannot be prevented. In addition, this method has not been practiced since a molded product has a portion where a skin material is missing and does not become a product. In order to effectively reuse the burr portion without preforming, it is necessary to keep the skin material and the parison separated at the burr portion.

[0006]

In order to solve the above problems and to separate the skin material and the parison and take out the burr portion, in the first invention, a pair of opposed molds is provided. A convex pinch-off portion disposed on the surface to pinch a parison and a skin material suspended from a die, and a convex outer mating surface surrounding the pinch-off portion and holding only the parison around an outer peripheral portion of the pinch-off portion. And a space between the pinch-off portion and the outer mating surface. In the second invention, the needle-like projection rod of the conduit for fixing the skin material in the space part in the first invention can be inserted from the side of the mold, and the tip of the needle-like projection rod or the outer peripheral part has air. This was a blow molding die provided with an outlet. Further, in the third invention, a convex pinch-off portion which is disposed on a surface of a pair of opposite molds and sandwiches a parison and a skin material hanging from a die, and a pinch-off portion on an outer peripheral portion of the pinch-off portion. A convex outer mating surface surrounding the portion and sandwiching only the parison, a space between the pinch-off portion and the outer mating surface, and a needle-like projection bar of a conduit for fixing a skin material to the space. A state in which the parison and the skin material in the space are separated from each other by supplying air from the outside to the space through the needle-shaped projection bar using a blow molding mold capable of being inserted from the side of the mold. As a result, a molded product obtained by laminating a parison and a skin material was obtained.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a mold according to the present invention, FIG. 2 is a structural explanatory view of a first embodiment of a needle-like projection according to the present invention, FIG. 3 is a structural explanatory view of a second embodiment of a needle-like projection according to the present invention, FIG. 4 is an overall vertical sectional view of a conventional lamination blow molding machine. FIG. 1 shows the shape of the outer peripheral portion of a mold pinch-off portion (R), which is a fundamental portion of the present invention. A space (P) is provided on the outer periphery of the pinch-off portion in an outer moat shape. The outer mating surface (Q) of the mold is generally flush with the pinch-off portion (R) (the inner mating surface of the mold), but may be slightly recessed from the pinch-off portion. In this case, the space (P)
It is necessary to ensure the airtightness of the vehicle to some extent.

Next, the needle-like projection (S) will be described. The gap between the needle-like projection (S) and the opposing cavity surface was almost the same as the total thickness when the parison (U) was crushed.
When the parison is pressed against the cavity surface on the side opposite to the skin material by air through the needle-shaped projection, the gap may be larger than the total thickness described above. In the present invention, the needle-like projections are advanced and retracted by a driving device (not shown) in accordance with the mold clamping and mold opening operations. However, they can be fixed to the skin material side mold. The interval between the needle-like projections (S) is set so that the parison hangs and does not contact the skin material (T).
mm pitch is appropriate. If this pitch is narrow, the number of needle-like projections (S) increases, and the manufacturing cost of the mold increases. If the parison (U) is too wide, the parison (U) hangs down and comes into contact with the skin material, and the parison (U) and the skin material (T)
Becomes difficult, and the burr portion cannot be reused.

As shown in FIG. 2 and FIG. 3, the shape of the needle-like projection (S) is a general bamboo spear type or a stopper for preventing slippage such as a fishing hook in order to prevent the movement of the skin material. Alternatively, the tip of the projection may be smoothed instead of the needle-shaped projection (S), and the parison may be pressed against the mold cavity surface facing the skin material at this tip.

The blowing of air into the space (P) may be performed simultaneously with or before the application of the blow pressure to the parison (during the mold clamping). The air blowing pressure may be equal to or lower than the blow pressure.

A method of laminating blow molding using the mold of the present invention configured as described above will be described below. First, the cut-out skin material is inserted into the needle-shaped projection (S) in the mold open state, and the skin material is fixed to the mold. When fixing the skin material to the mold, auxiliary fixing means (for example, a clip or an adhesive tape) can be used so that the end of the skin material is in contact with the mold surface (to prevent it from turning over). Means for applying tension to the skin material to prevent wrinkles from occurring can also be used.

Next, a pre-blow is performed into the parison, and then a mold is clamped and a blow pressure is applied to the space (P) and the parison. In this case, the air pressure blown into the space may be lower than the blow pressure. On the other hand, air existing between the parison and the skin material and the mold cavity surface is naturally exhausted from a vent hole formed in the mold, or is forcibly sucked using a suction fan or a vacuum pump. Thereby, the surface property of the molded article is improved. After completion of cooling, the molded product is taken out. As described above, by taking out the molded product by performing the almost same lamination blow molding, the resin is pressed against the mold surface by air or / and needle-like projections at the burrs, and separated from the skin material. Since it is held in a state of being cooled and solidified, it does not adhere to the skin material. In this way, by employing the mold of the present invention and the molding method using the same in the blow molding of the shallow object, the skin material and the parison can be formed at the burr without changing the conventional molding method. Can be taken out in a state where is completely separated.

[0013]

According to the present invention, the skin material and the parison can be reliably and efficiently separated from each other at the burr, and the skin material is not mixed with the base resin, so that the quality of the molded product is not reduced without lowering the quality of the molded product. It became possible to reuse parts.
This is a useful invention to meet the demands of the resource saving era.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold according to the present invention.

FIG. 2 is a structural explanatory view of Example 1 of a needle-like projection according to the present invention.

FIG. 3 is a structural explanatory view of Example 2 of a needle-like projection according to the present invention.

FIG. 4 is an overall vertical sectional view of a conventional lamination blow molding machine.

[Explanation of symbols]

 P Space part Q Mold outside mating surface R Pinch-off part (Mold inside mating surface) S Needle-like projection T Skin material U Parison

Claims (3)

[Claims] 1. A pinch-off portion, which is provided on a surface of a pair of opposing dies and sandwiches a parison suspended from a die and a skin material, and a pinch-off portion surrounding an outer peripheral portion of the pinch-off portion. And a convex outer mating surface for sandwiching only the parison, and a space provided between the pinch-off portion and the outer mating surface. 2. A needle rod of a conduit for fixing the skin material in the space according to claim 1 can be inserted from a side surface of a mold, and air is blown out to a tip portion or an outer peripheral portion of the needle rod. A blow molding die having a mouth. 3. A pinch-off portion having a convex shape disposed between surfaces of a pair of opposed dies and holding a parison suspended from a die and a skin material, and an outer peripheral portion of the pinch-off portion surrounding the pinch-off portion. And a convex outer mating surface for holding only the parison is provided, a space is provided between the pinch-off portion and the outer mating surface, and a needle-like projection bar of a conduit for fixing a skin material in the space is molded. Using a blow-molding mold that can be inserted from the side surface, air is supplied from the outside to the space through the needle-like projection bar, and the parison and the skin material in the space are separated from each other in the space. A blow molding method characterized by obtaining a molded product bonded to a skin material.