JPS6243854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for blow molding a plastic container, which is manufactured by blow molding and comprises a main body, a lid, and a hinge that connects them together.

[Conventional technology]

Conventionally, plastic containers manufactured by blow molding consisting of a main body made of a single plastic material, a lid, and a compression-thinned hinge that integrally connects the main body and the lid have been disclosed in Japanese Patent Publication No. 49-1983.
This is known as shown in Japanese Patent No. 18748.

[Problem to be solved by the invention]

However, conventional blow-molded plastic containers have the following drawbacks. That is,
The hinge base formed on the parting line during blow molding is configured to be on the same line as the mating surface of the container, so excessive stress is applied to the hinge when the container is used. Since the width of the hinge up to the base of the hinge is small, the hinge strength is poor, and this drawback is particularly noticeable in containers made of polyolefin plastic materials such as polyethylene. Due to the factors described above, conventional containers have poor repeated bending characteristics of the hinge, and the life of the container itself has to be shortened. The applicant came up with the idea of forming a hinge with a large width as a means to solve the above-mentioned drawbacks, but even if the hinge was formed in this way, a gap would be created between the mating surfaces of the container, resulting in a container with poor protection properties for stored items. Ta. Therefore, in the blow molding mold for blow molding, the hinge base formed on the parting line is formed at a position farther from the mating surface of the container, and the hinge width is made larger, thereby solving the above drawbacks. I tried. However, such molds for blow molding plastic containers have caused new problems such as (1), (2), and (3) below.

(1) As shown in Fig. 7, as the mold consisting of one half mold 23 and the other half mold 24 is closed, the parison 21 inside the mold deforms along the mold cavity surface. To go. At this time, among the cavity surfaces that mold the vicinity of the hinge of the plastic container, the compressed part 26A for hinge molding of one half mold 23 is
or the hinge side end 40 of the container mating surface molding part 27A of the other half mold 24, or the opposite end 3
0.40, there was a risk that the parison 21 would be torn due to shearing force, causing molding defects.

(2) As the material that has been sheared and compressed by the opposing ends 30 and 40 moves just before the mold is closed, it may break near the container mating surface of the molded plastic container or at the hinge. This may cause the appearance of meat to deteriorate.

The present invention provides a mold for blow molding plastic containers that has excellent blow moldability and can prevent appearance defects.

[Means for solving problems]

The present invention is a mold for blow molding a plastic container, which is composed of a pair of half molds 13 and 14, and one half mold 13 has two convex shapes forming the main body and the inner wall of the lid of the container to be blow molded. Cavity surface 15
A, 15A is formed, and the convex cavity surface 1
A compressed part 16A is formed between 5A and 15A to sandwich the parison and form a hinge of the container, and the other half mold 14 has two concave cavities that form the main body of the container to be blow molded and the outer wall of the lid. Surface 15
B, 15B are formed, and a compression part 16B is formed between the two concave cavity surfaces 15B, 15B to sandwich the parison to form a hinge of the container,
The compressed part 16A of one half mold 13 has a tapered end and is formed to protrude in the direction of the other half mold 14, and the compressed part 16B of the other half mold 14 has a tapered end that is sloped toward the other half mold 14. The opposing compressed portions 16A, 16B and both ends thereof are configured to match each other, and a parting line defined by both ends of the compressed portions 16A, 16B. Reference numerals 9' and 9' relate to molds for blow-forming plastic containers, characterized in that they are inclined to expand outward from the mating surfaces of the molds.

[Effect]

In the present invention, when the mold is closed, a protruding compression part with a tapered beveled end of one mold half and a recessed compression part with a flared beveled end of the other mold half are used. Since approximately the middle of the parison is evenly clamped and compressed between the two parts, there is no risk that the parison will come into contact with the inner surface of the mold locally and break.
By evenly clamping and compressing, the movement timing of the parison clamped at the inclined end of the compression part and the movement timing of the parison clamped at the compression part other than the end part are almost the same, so that the molding is not possible. There is no bending caused by abnormal material movement of the parison near the hinge or container mating surface, resulting in excellent formability.

〔Example〕

An embodiment of the present invention will be described below based on the drawings. 1 and 2 show a plastic container 1 manufactured by a blow molding mold according to the invention, which container 1 is made of a single plastic material such as polyethylene, polypropylene, vinyl chloride, ethylene, etc. - It is made of thermoplastic plastic such as vinyl acetate copolymer or holamide, and is composed of a main body 2, a lid 3, and a compressed thin hinge 4 that connects the main body 2 and the lid 3 together. The hinge 4 is 2 to 40 times preferably 5
It is compressed at a compression ratio of ~30 times, and is formed to have a wall thickness of 0.2 mm to 1.0 mm, preferably 0.3 to 0.8 mm. still,
The compression ratio is the ratio of the thickness of the parison before compression to the thickness after compression. The main body 2 and the lid 3 each have a double wall structure with inner walls 2A, 3A and outer walls 2B, 3B, 5 is a storage section, 6 is a mating surface of the container, and 7 is a place where separate items are attached. It is a locking tool.
The hinge bases 8 of the hinge 4 are formed on the parting line during blow molding, and are spaced outwardly from the mating surfaces 6 of the container by approximately 1 mm to 15 mm, preferably 2 mm to 8 mm. Note that the mating surface 6 of the container and the hinge base 8 are molded so as to be arranged substantially parallel to each other. A parting line 9 connecting the hinge base 8 and the mating surface 6 is inclined at an angle of about 10 degrees to 70 degrees.

3 and 4 show a blow-molding mold and other manufacturing equipment for the blow-molded plastic container 1 according to the present invention, in which 10 is an extrusion head, and 11 is for plasticizing thermoplastic plastic such as polyethylene. A cylindrical parison, 12 is half-shaped 1
3. It is a split type mold consisting of half molds 14. One half mold 13 includes the main body 2 and the inner walls 2A and 3 of the lid body 3.
A convex cavity surface 15A forming the shape A and a compressed portion 16A forming the hinge 4 are formed. The other half mold 14 has the main body 2 and the outer walls 2B and 3 of the lid 3.
A concave cavity surface 15B forming a portion B and a compressed portion 16B forming a hinge 4 are formed.
Note that 17 is a blowing nozzle. As shown in FIG. 4, the mating surface 6 of the container and the hinge 4 are formed on the parting line 9 of the mold 12, and the parting line 9' connecting the hinge 4 and the mating surface 6 of the container is about 10 degrees. Formed at an angle of 70 degrees from
The compressed portion 16A forming the hinge 4 of the half mold 13 protrudes in a trapezoidal shape with a tapered end, and the compressed portion 16B forming the hinge 4 of the half mold 14 is inclined to widen toward the end. It is recessed to have an end.

Next, a method for manufacturing the plastic container 1 using the blow molding mold according to the present invention will be explained.
First, a thermoplastic such as polyethylene is melt-kneaded by an extruder (not shown) and extruded from an extrusion head 10 as a plasticized cylindrical parison 11. Parison 11 is an open mold 12
That is, a pair of molds 12 disposed between the half molds 13 and 14 and protruding from the convex cavity surface 15B of one half mold 13 is then closed, and the parison 11 is clamped. At this time, since the parting lines 9' located at both ends of the compressed parts 16A and 16B, which connect the hinge 4 and the mating surface 6 of the container, are formed at an angle, when the mold 12 is closed, the parison 11 There is no fear that it will break.

That is, when closing the mold, one half mold 13
Approximately the middle of the parison 11 is evenly sandwiched and compressed by a protruding compression part 16A having a tapered end and a recessed compression part 16B having a widening end of the other half mold 14. Therefore, there is no risk that the parison 11 will partially contact the inner surface of the mold and break. Furthermore, by evenly pinching and compressing, the movement timing of the parison 11 (at the parting line 9') held at the inclined ends of the compression parts 16A and 16B and the compression parts 1 other than the ends are also determined.
6A and 16B are moved to the parison 11 (at the parting line 9) at almost the same time, so the formed hinge 4 and the vicinity of the container mating surface 6 are bent due to abnormal material movement of the parison. Excellent moldability with no buildup. Next, pressurized fluid such as compressed air is blown into the parison 11 by the blowing nozzle 17 to form the main body 2 and the lid 3 by the convex cavity 15A and the concave cavity 15B, and the compression part 16A,
At 16B, approximately the middle of the parison 11 is compressed to form a compressed and thinned hinge 4. Next, after cooling the molded product formed from the parison 11, the mold 12 is opened, the molded product is removed, and excess burrs are removed, thereby producing a container 1 as shown in FIGS. 1 and 2. Ru. In addition, when removing the burrs formed on both ends of the hinge 4 of the molded plastic container 1, it is necessary to remove the slanted part of the end of the hinge 4 with the molded container 1 closed, as shown in FIG. line 9, 9', 9
Remove the burr F along. At this time, parting lines 9, 9', 9 formed from the hinge base 8 on the main body 2 side of the container 1 to the container mating surface 6.
Since the distance between the parting lines 9, 9', and 9 formed from the hinge base 8 on the lid 3 side of the container 1 to the container mating surface 6 does not change suddenly, the cutter blade is easily removed when removing burrs. Since the resistance applied to other parts does not change drastically, burr removal work can be carried out smoothly.

FIG. 5 shows another example of a plastic container manufactured by the blow molding die according to the present invention, in which both ends 4' of the hinge 4 are curved inward. The hinge base 8 formed on the parting line during blow molding is formed at a position away from the mating surface 6 of the container, and the parting line 9' connecting the hinge base 8 and the mating surface 6 is formed at an angle. In order to curve both ends 4' of the hinge 4 inwardly as shown in FIG. It can be easily formed by moving the blade obliquely to the outer surface of the container and removing burrs, and since the hinge base 8 is formed longer than the center, the bending strength of the hinge 4 can be greatly increased.

As described above, the blow molding mold of the present invention is a mold for blow molding a plastic container, which is composed of a pair of half molds 13 and 14, and one half mold B includes the main body and the lid of the container to be blow molded. Two convex cavity surfaces 15A, 15A forming the inner wall of the container are formed, and a compressed portion 16A is formed between the convex cavity surfaces 15A, 15A to sandwich the parison to form a hinge of the container. The mold 14 is formed with two concave cavity surfaces 15B, 15B that form the outer walls of the main body and lid of the container to be blow-molded.
A compressed part 16B is formed between B to sandwich the parison and form a hinge of the container, and the compressed part 16A of one half mold 13 has a tapered inclined end and extends in the direction of the other half mold 14. The compressed part 16B of the other half mold 14 is formed in a recessed manner with an end part that is slanted toward the other half, and the opposing compressed parts 16A, 16B and both ends thereof are formed so as to match each other. In addition to being configured, the compression section 16A,
The parting lines 9', 9' defined at both ends of the mold 16B are inclined so as to expand outward from the mating surface of the mold, so the manufactured plastic container has excellent hinge strength. Since there is no gap between the mating surfaces of the container, it is possible to obtain a container with excellent protection properties for stored articles. In addition, since the parting line connecting the hinge base and the mating surface is formed at an angle, it has excellent blow moldability, and since it is possible to prevent creases and accumulations of flesh near the hinge, it is possible to obtain a container with excellent appearance characteristics. can.

The plastic container obtained using the blow molding mold of the present invention may have a main body and a lid having a hollow double-walled structure, or may have a double-walled structure in which an inner wall and an outer wall are joined. Furthermore, the plastic container of the present invention can be used as a container for storing calculators, typewriters, measuring instruments, cameras, radios, binoculars, tanks, bottles, tools, etc., or various housing members, and its uses are not limited in any way.

〔Effect of the invention〕

According to the blow molding mold of the present invention, problems such as poor molding due to lack of expansion pressure caused by the parison being torn near the compression part in the mold are solved, and the blow molding property is excellent, and the bending part near the hinge is improved. Since it is possible to prevent the occurrence of lumps, etc., it is possible to obtain a plastic container with excellent appearance characteristics.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a plastic container manufactured using a blow molding mold according to the present invention, FIG. 2 is a rear view of the same, and FIG. 3 is a blow molding plastic container according to the present invention. FIG. 4 is a sectional view taken along the line A--A in FIG. 3, and FIG. 5 is a main part of another example of a plastic container manufactured using the blow molding mold of the present invention in an open state. A top view, and FIG. 6 is a perspective view of the main parts near the hinge to explain the burr removal process.
FIG. 7 is a cross-sectional view of a conventional blow molding die near the compression part immediately before the die is closed. 1...Plastic container, 2...Main body, 3...
Lid body, 4... Hinge, 6... Container mating surface, 9
...parting line.

Claims (1)

[Claims] 1 A mold for blow molding a plastic container consisting of a pair of half molds 13 and 14, one half mold 13
There are two convex cavity surfaces 15A, 15A forming the inner wall of the main body and lid of the container to be blow molded.
are formed, and the convex cavity surfaces 15A, 15
A compressed part 16A is formed between A and A to sandwich the parison and form the hinge of the container, and the other half mold 14 has two concave cavity surfaces 15B which form the outer wall of the main body and lid of the container to be blow-molded. , 15B are formed, and the two concave cavity surfaces 15B,
A compressed part 16B is formed between the mold half 15B to sandwich the parison and form a hinge of the container.
The compression part 16A of No. 3 is formed to have a tapered inclined end and protrude in the direction of the other half mold 14,
The compression portion 16B of the other half mold 14 is formed in a concave manner with an end portion slanted toward the end, and the opposing compression portions 16A, 16B and both ends thereof are configured to match each other and Part 16
For blow forming of plastic containers, the parting lines 9', 9' defined at both ends of the molds A, 16B are inclined so as to expand outward toward the mating surfaces of the molds. Mold.