JPH1034740A - Mold for blow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cut-off property and to enable the molding of a hollow molding without flashes and whiskers in a part corresponding to a cut-off part by installing a water leading pipe in which the temperature of the cut-off part during molding is specified by circulating water or oil close to the cut-off part. SOLUTION: Besides, a mold bottom part 3 has a bottle molding part 8 which is formed as a projection corresponding to the outside shape of the part 8. In the part 8, a cut-off blade 9 for cutting a parison off is installed. Since the blade 9 plays a roll to cut the parison off, it is formed from a steel which is hardly abraded. A water leading pipe 11 which circulates water or oil and controls the temperature of the cut-off part during molding to be 60-100 deg.C is installed close to the cut-off part 10 in which the blade 9 is installed. Besides, in order to make the shape of the pipe 11 clear, a necessary machined hole is omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for blow molding, and more particularly to a hollow molded product having no burrs or whiskers (produced by being stretched at the time of cutting, etc.) at a portion corresponding to a cutout portion. It relates to a mold for blow molding to be obtained.

[0002]

2. Description of the Related Art For example, in direct blow molding for molding a container such as a bottle with a handle, there is a problem that burrs and whiskers are easily generated in the molded container. To eliminate such burrs and mustaches,
For example, the following three methods can be considered.

(1) The biting blade is made thinner to improve the mold closing force. (2) In addition to the above (1), the mold closing force itself is improved. (3) Eliminate the bite of the cutting blade and make it even.

[0004] However, in the above (1), if the cutting edge is made thinner, the mold closing force per unit area is increased and the cutting performance is improved, but if it is made too thin, there is a problem in strength and durability.

In the above (2), if the mold closing force is increased, it is necessary to increase the size of the molding machine, which is not appropriate in terms of cost.

In the above (3), it is possible to make the balance of the mold closing force uniform by an adjustment mechanism called a platen support. However, the mold closing force is deprived by the platen support, and the mold The closing force will be reduced.

In addition, conventionally, as disclosed in, for example, Japanese Utility Model Application Laid-Open No. 56-128217, a ceramics insulator is detachably interposed between the divided surfaces of the mold body, and the ceramics insulator is electrically connected to the ceramics insulator. A blow molding die has been proposed in which a heat wire is embedded so that burrs and mustaches are blown off by the heat.

However, since a ceramic insulator must be interposed between the divided surfaces of the mold and a heating wire must be embedded in the ceramic insulator, the structure of the mold is complicated and the cost is considerably increased. . In addition, it is necessary to pay attention to disconnection of the heating wire, electric leakage, and the like, and the risk increases.

Further, Japanese Patent Application Laid-Open No. 6-344429 discloses that a mold is closed at a predetermined pressure, and the mold closing force of the mold is pulsated in that state to reduce the thickness of burrs and whiskers. There has been proposed a blow molding method in which a parison is cut off.

[0010] However, according to this method, when the present inventors conducted experiments, it was not so effective, and it was difficult to suppress the generation of burrs and whiskers.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a blow molding die capable of improving a cut-off property and forming a hollow molded article without burrs or whiskers at a portion corresponding to a cut-off portion.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a blow molding die used for forming a hollow molded product by blow molding. 60 ° C to 10 ° C
The object has been achieved by providing a blow molding die provided with a water guide tube at 0 ° C.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a blow mold according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of the blow molding die of the present embodiment, FIG. 2 is a left side view of the blow molding die shown in FIG.
3 is a front view of the blow molding die shown in FIG. 1, FIG. 4 is a plan view of the blow molding die shown in FIG. 1, and FIG. 5 is a view of a bottle formed by the blow molding die of the present embodiment. It is a perspective view.

FIG. 1 shows a blow molding die 1 according to this embodiment.
As shown in FIG. 4 to FIG. 4, a mold used when a hollow molded product such as a bottle is molded by blow molding. In the present embodiment, only one of the blow molding dies 1 divided into two along the parting line is illustrated and described.

The blow molding die 1 of this embodiment will be described in more detail. Mold 1 for blow molding of this embodiment
As shown in FIG. 1, the mold comprises a mold body 2 for molding the bottle body and a mold bottom 3 for molding the bottle bottom.

The mold body 2 has a bottle body molding portion 4 (cavity) formed as a concave portion corresponding to the outer shape of the bottle body, excluding the bottle bottom. The mold main body 2 is provided with a cooling water introduction passage 5 for cooling the blown and expanded bottle main body.

The cooling water introduction passage 5 is provided at a position close to the bottle body forming portion 4 so as to stretch around the entire bottle body forming portion 4 in order to efficiently cool the bottle body. Cooling water for cooling the bottle body is circulated through the cooling water introduction passage 5.

The cooling water inlet 6 and the cooling water outlet 7 for circulating the cooling water through the cooling water introduction passage 5 are
As shown in FIGS. 2 and 3, they are provided on the bottom surface of the mold bottom 3 connected to the cooling water introduction passage 5.

On the other hand, as shown in FIGS. 1 to 3, the mold bottom portion 3 has a bottle bottom forming portion 8 formed as a projection corresponding to the outer shape of the bottle bottom portion. The bottle bottom forming section 8 is provided with a cutting blade 9 for cutting off the parison. Since the biting blade 9 serves to cut the parison, it is formed of a hard-to-wear steel material.

A water guide pipe 11 is provided in the vicinity of the cutting portion 10 provided with the cutting blade 9 so as to circulate water or oil so that the temperature of the cutting portion 10 at the time of molding is 60 ° C. to 100 ° C. ing. 1 to 4, in order to make the shape of the water pipe 11 clear,
Originally, the processing holes necessary for obtaining the shape as shown in the figure are omitted.

As shown in FIGS. 1 to 4, the water pipe 11 is located at a position as close as possible to the biting blade 9.
It is provided so as to be substantially parallel to the biting blade 9. In order to surely cut off burrs and whiskers by the cutting blade 9, water or oil having a temperature such that the temperature of the cutting portion 10 at the time of molding is 60 ° C. to 100 ° C. is circulated through the water pipe 11. It has been made like that. In the present embodiment, water or oil at a temperature of 60 ° C. to 65 ° C. is flowed through the water pipe 11.

The temperature of the cutting portion 10 at the time of molding is preferably as high as possible. In particular, in the case of molding polyethylene (PE) or polypropylene (PP), the temperature is 60 to 100 ° C.
Is good. The temperature of the cutout 10 during molding is 60 ° C.
If it is less than 50%, the effect is not easily obtained, and a whisker is likely to be generated. 100
If the temperature is higher than ℃, cooling around the cutting part cannot be performed sufficiently.
The cooling time becomes longer.

An inlet 12 and an outlet 13 for circulating water or oil through the water pipe 11 are provided on the bottom of the mold bottom 3 as shown in FIG.

According to the blow molding die configured as described above, water or oil at a predetermined temperature is circulated through the water guide tube 11 so that the temperature of the cut-off portion 10 becomes 60 ° C. to 100 ° C. Therefore, as shown in FIG. 5, it is possible to form a bottle 14 free of burrs and whiskers.

By setting the temperature of the cut-off portion 10 during molding within the above range, the generation of burrs and whiskers can be eliminated because the solidification time of the molten parison corresponding to the cut-off portion 10 is reduced to other portions. It is presumed that since the length is longer than that, it is likely to be easily crushed and cut.

As described above, according to the blow molding die of the present embodiment, only the portion near the cutting edge 9 is heated to a high temperature (60 ° C. to 100 ° C.) with respect to other portions, so that the appearance of the bottle product is improved. In addition, the cooling time and the cycle are not different from those of the conventional mold without the water pipe 11, and the product portion corresponding to the cutout portion 10 is finished finely.

Further, according to the blow molding die of the present embodiment, since the temperature control of the cutout portion 10 is controlled by the temperature of water or oil, there is no difference from the conventional die designing and processing. There is an advantage that only the position design and processing of the water guide pipe 11 are required, and cost and time are not required.

As described above, the blow molding die to which the present invention is applied is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

For example, in order to control the temperature of the cutting portion 10, the flow rate of water at 10 ° C. to 60 ° C. is extremely reduced (for example, 0.1%).
(1 to 1 liter / min), the same effect can be obtained even when the temperature of the cutting portion 10 is set to 60 ° C to 100 ° C.

[0031]

As is apparent from the above description, according to the blow molding die according to the present invention, a hollow molded product having improved cut-off property and having no burrs or whiskers at a portion corresponding to the cut-off portion. A mold for blow molding that can be molded can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a blow molding die according to an embodiment.

FIG. 2 is a left side view of the blow molding die shown in FIG.

FIG. 3 is a front view of the blow molding die shown in FIG. 1;

FIG. 4 is a plan view of the blow mold shown in FIG. 1;

FIG. 5 is a perspective view of a bottle formed by the blow mold according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blow molding die 2 die main body 3 die bottom 5 cooling water introduction passage 9 biting blade 10 biting portion 11 water pipe

Claims (1)

[Claims] 1. A blow molding die used when a hollow molded article is molded by blow molding, wherein water or oil is circulated near the cutout to raise the temperature of the cutout at 60 ° C. A blow molding die, comprising a water guide tube at 100 ° C.