JPH0948064A - Blow molding die and blow molding method using this die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the strength of a cutoff part of a parison when blow- molded. SOLUTION: A die A for blow molding consists of a pair of forces A1, A2 of a split die. Projecting strips A5 for forming a W reinforcing part are formed almost in parallel with the butting faces of the forces A1, A2 of the split die, on the inner faces of cavities A3, A4, in the neighborhood of the butting faces of the forces A1, A2 of the split die. Consequently, when the forces A1, A2 of the die are butted to each other, a narrow groove A6 is formed between the pair of projecting strips A5. This width of the narrow groove A6 grasps a parison, and is adequately wide for the inner walls of the parison to be in close contact with each other. The preferable with of the groove should be about 1.9-1.5 times the wall thickness of the parison when grasped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding die and a blow molding method using the die.

[0002]

2. Description of the Related Art A conventional hollow molded article is disclosed in Japanese Patent Application Laid-Open No. Sho 62
There is one disclosed in Japanese Patent Publication No. 284721. Hollow molded articles are described in the first and fourth parts of the "claims" of this publication.

[0003]

However, there is no description in the above publication regarding reinforcement at the cut-out portion at the time of molding. It is an object of the present invention to provide a market with a blow molding die in which the strength of a bite cut portion at the time of blow molding of a parison is improved and a blow molding method using this die.

[0004]

[Means for Solving the Problems] In order to achieve the above object, a specified invention is a split mold for holding and blowing a single parison, in the vicinity of a mating surface of the split mold,
A blow molding die is characterized in that a W-shaped reinforcing portion forming ridge is formed on the inner surface of the cavity substantially parallel to the mating surface. In order to achieve the above-mentioned object, it is characterized in that a portion of the die including the protrusion is provided so as to be independently movable with respect to other portions of the split die. Sometimes it's good.

In order to achieve the above-mentioned object, a method invention which is a related invention uses the above-mentioned mold,
After pushing a single parison from the die head and positioning it in the open split mold, the split mold is closed and the parison is cut off by the cut-out part of the split mold and the ridges allow the parison to move inside the parison. The blow molding method is characterized in that the wall surfaces are brought into close contact with each other, air is blown into the parison to form a hollow molded product having a desired shape, and an inner W-shaped reinforcing portion of the bite cut portion is formed. is there.

In order to achieve the above-mentioned object, the method of the related invention uses the above-mentioned mold, and the parison supplied between a pair of split molds has a part facing one mold. After extruding a single parison whose parison color or material is different from the parison color or material facing the other mold from a single blow die head and placing it in the open split mold, Close the split mold and cut the parison with the cut parts of the split mold to cut away the boundaries of different colors or materials of the parison, and stick the inner walls of the parison to each other by the protrusions to blow air into the parison. A blow molding method is characterized in that a hollow molded product having a shape is formed, and a W-shaped reinforcing portion is formed inside the biting portion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 This embodiment is a representative embodiment of the invention described in claim 1, and will be described together with the embodiments of the invention described in claims 3 and 4. In FIG. 1, A is a blow molding die, which comprises a pair of split dies A1 and A2. A W-shaped reinforcing portion forming ridge is formed on the inner surface of the cavity in the vicinity of the mating surface of the split mold substantially parallel to the mating surface. Therefore, when the pair of split molds A1 and A2 are combined with each other, a narrow groove A6 is formed between the pair of protrusions A5, and this width holds the parison described later, and makes the inner walls of the parison stick to each other. It has a sufficient width and is preferably set to about 1.9 to 1.5 times the thickness of the parison when sandwiched.
The parison supplied is a white to light color for the semi-circular portion 10 of the cylindrical container B, which is a type of hollow molded product made of a single parison, while the remaining semi-circular portion 11 is black or A dark green or the like is provided so that the boundary portion 12 of the semi-circular portion 10 and the remaining semi-circular portion 11 which are different in color from each other serves as a resin cutting portion when the pair of blow molding dies are clamped. Supply the parison.

In blow molding using the mold A, a single parison (not shown) is extruded from a blow die head (not shown) as described above, and the split molds A1 and A2 are opened. After being placed inside, this split mold A
1, A2 is closed, the parison is cut through the boundary portions of mutually different colors to form the cut-out portion 12, and the inner surfaces of the parison are brought into close contact with each other by the projection A5, and the W-shaped reinforcing portion 13 is formed as described above. It is formed inside the biting part 12. The central mountain portion 13a of the reinforcing portion 13 is formed by welding and unifying the inner surfaces of the parison, and the height thereof is about 1.9 to 1.5 times higher than the thickness of the parison. Valleys 13b are formed on both sides, and the peaks 13a are formed.
Does not project from the peripheral surface of the cylindrical container B, which is a type of hollow molded product.

A cylindrical container B, which is a kind of hollow molded product molded in this way, has a distinctly different color on the mating surface of the mold A, and the inner wall surface is inside the bite cut portion 12. The W-shaped reinforcing portion 13 is formed by mutually fusing each other. In addition, immediately before opening the split molds A1 and A2, the part C including the protrusions A5 for forming the reinforcing portion 13 is cut off before the other parts of the split molds A1 and A2. Retreat to the position indicated by the dashed line. Split mold A in this state
In some cases, the hollow molded product may be taken out by using 1 or A2.
(This corresponds to a typical embodiment of the invention according to claim 2 <see FIG. 4>.

Embodiment 2 This embodiment is a typical embodiment of the invention described in claim 4, and is different from Embodiment 1 in that the semicircular portion 10 and the remaining semicircular portion 11 are made of resin. The materials are different, and the same reference numerals as those in the first embodiment indicate the same configurations and operations. The drawings of this embodiment refer to FIGS. 1 to 3.

[0011]

According to the first aspect of the present invention, when molding is performed by using this mold, a reinforcing portion formed by fusing the inner walls of the parison with each other can be formed at the same time when the resin is cut off by blow molding. The strength of the resin cut portion of the hollow molded product can be improved.

A narrow groove is formed between the pair of ridges when the pair of split molds are combined, and the central mountain portion of the reinforcing portion formed by the narrow groove has inner surfaces of the parison. Is formed by welding integrally, and its height is higher than the thickness of the parison, so the contact area between the resins at the bite section becomes larger, and the peel strength of the hollow molded article at this bite section is increased. Can be increased. According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is arranged that the portion including the abrupt section is independently movable with respect to the other portion of the split mold. Because of the feature, when the hollow molded product is molded into a non-cylindrical shape like a rectangular table, the molded hollow molded product can be easily taken out.

According to the third aspect of the present invention, there is provided a hollow molded article which is capable of exerting the effect of the die according to the first aspect and which is improved in the strength of the resin cut portion and the peeling strength at the cut portion. Can be molded. It should be noted that the invention is not limited to the above embodiment, and the semicircular portion and the remaining semicircular portion may be formed of a single layer of resin, and the shape is not limited as long as it is a hollow molded product.

According to the fourth aspect of the invention, the effect of the die according to the first aspect can be exhibited, and the strength of the resin cutting portion having different colors or materials and the peeling strength at the cutting portion can be improved. Hollow molded products can be molded.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a mold according to a first embodiment.

FIG. 2 is a perspective view of a hollow molding product using the mold of FIG.

FIG. 3 is a cross-sectional view showing a part of the reinforcing portion in FIG.

FIG. 4 is a schematic cross-sectional view showing another mold.

[Explanation of symbols]

 12 Eating part 13 Reinforcing part

Claims (4)

[Claims] 1. A split mold for holding and blow molding a single parison, and a W-shaped reinforcing portion forming ridge is formed on the inner surface of the cavity near the mating face of the split mold with respect to this mating face. Blow molding die characterized by being formed substantially parallel to each other. 2. The blow molding die according to claim 1, wherein the portion including the protrusion is provided so as to be independently movable with respect to the other portion of the split die. 3. A method of blow molding using a mold according to claim 1 or 2, wherein a single parison is extruded from a blow die head and positioned in an open split mold, and then this split is performed. The mold is closed, the parison is cut by the cut-out part of the split mold, and the inner wall surfaces of the parison are brought into close contact with each other by the projections, and air is blown into the parison to form a hollow molded product of a desired shape. A blow molding method, which comprises forming a W-shaped reinforcing portion inward of the cut-out portion. 4. The method of blow molding using a mold according to claim 1 or 2, wherein the parison supplied between the pair of divided molds has a color or a color of the parison facing one mold. A single parison whose material is different from the color or material of the parison facing the other mold is extruded from a single blow die head, placed in an open split mold, and then this split mold is opened. Close and cut the parison with the cutting part of the split mold to cut off the boundary part of different colors or materials of the parison, and make the inner wall surface of the parison adhere to each other by the protrusions and blow air into the parison to form the desired hollow molding A blow molding method, characterized in that a W-shaped reinforcing portion is formed inside the bite cut portion.