JP3723877B2 - Primary blow mold for double blow molding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a primary blow mold of a double blow molding apparatus for molding a biaxial stretch blow molding basket having high heat resistance and high pressure resistance.
[0002]
[Prior art]
Among the biaxially stretched blow-molded soot containers represented by polyethylene terephthalate resin-made soot containers, double blow-molded means is known as means for obtaining a particularly heat-resistant soot container.
[0003]
This double blow molding means performs a biaxial stretch blow molding of a preform molded in a desired shape in advance into an intermediate molded product having a shape and size set according to the shape and size of the target container. Then, this intermediate molded product is heated and freely shrunk and deformed, and then the heat-shrinked and deformed intermediate molded product is biaxially stretch-blow-molded into a target container.
[0004]
In this double blow molding means, the intermediate molded product formed by greatly stretching and deforming the preform is freely heat shrink deformed, so that the internal strain generated by this free heat shrink deformation is completely eliminated. Therefore, the molded container has only a slight internal strain due to a small amount of stretching from the intermediate molded product to the container, and therefore, thermal deformation generated in the container can be suppressed within a small range. This makes it possible to obtain a container with high heat resistance and pressure resistance.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional technology, as shown in FIGS. 8 and 9, when the intermediate molded product s formed by biaxial stretch blow molding is heated and freely thermally contracted, the heat of the body s1 is obtained. shrinkage variation becomes uneven, heat shrink variations which particularly along the circumferential direction, as shown in FIG. 9, is the virtual inclined at a predetermined angle of inclination (approximately 30 degrees) relative to the parting line position p1 When the intermediate molded product s is biaxially stretched and blow molded into a finished container, the stretch amount in the radial direction is greatly different between the portions of the same circumferential portion. However, due to the difference in the amount of stretching, there has been a problem that improper thermal deformation occurs or is likely to occur in the container.
[0006]
As described above, it is unknown why the flat cross-sectional shape of the body portion s1 of the intermediate molded product s is elliptically deformed by heat shrinkage, but this irregularly deformed shape functions as a gas exhaust port in the molding space. Since it has a tendency to have a substantially constant positional relationship with respect to the parting line, it seems that there is some relationship with the exhaust form of the gas in the molding space.
[0007]
Accordingly, the present invention has been developed to solve the above-described problems in the prior art, and the gas in the molding space of the primary blow mold for biaxially stretching blow molding the intermediate molded product is a peripheral to the intermediate molded product. It is a technical problem to make the influence along the direction as uniform as possible, so that the heat shrink deformation generated in the body part of the intermediate molded product is as uniform as possible along the circumferential direction. For the purpose.
[0008]
[Means for Solving the Problems]
Among the present invention for solving the above technical problems, the means of the invention according to claim 1 is:
In double blow molding, a primary blow mold composed of a pair of split molds and one bottom mold used to biaxially stretch blow mold an intermediate molded product from a preform;
Providing a plurality of slit portions that are formed over substantially the entire height range along the extending direction in the height direction on the mold surface of the split mold, and form an exhaust port of a gas exhaust path in the mold space;
Disposing the slit portions in parallel so as to reduce the bias as much as possible in the exhaust capacity distribution along the circumferential direction of the mold surface,
It is in.
[0009]
Since the plurality of slit portions which are exhaust function portions are provided in parallel in the circumferential direction on the molding surface of the pair of split molds, the primary blow mold includes the mold matching slits of the pair of split molds, The plurality of exhaust function portions are distributed along the circumferential direction of the mold surface, and the distribution form of the plurality of exhaust function portions is as uneven as possible in the exhaust capacity distribution along the circumferential direction of the mold surface. It is set so that there are few things.
[0010]
Therefore, when the preform is biaxially stretch blow-molded into an intermediate molded product, the gas (air) exhaust between the preform and the mold surface accompanying the blow molding is substantially uniform along the circumferential direction. This can be achieved, whereby the influence of exhaust on the intermediate molded product during blow molding is substantially equal over the entire circumference.
[0011]
In this way, when the intermediate molded product is biaxially stretch blow molded so that the influence of exhaust on the intermediate molded product during blow molding, that is, the influence of gas in the molding space is substantially equal over the entire circumference, after molding, The heat-shrinkage deformation generated in the body part of the intermediate molded product occurred without deviation along the circumferential direction, and the body cross-sectional shape after the heat-shrinkage deformation was substantially the same as the shape at the time of stretch molding.
[0012]
The invention according to claim 2 is the invention according to claim 1, wherein a plurality of slit portions including the mold-matching slit for forming the parting line are arranged at substantially equal intervals along the circumferential direction of the molding die surface. Is added to that.
[0013]
The invention according to claim 2 is configured such that the die-matching slit is handled as an exhaust function part that exhibits an exhaust capability equivalent to that of the slit part, and the arrangement setting of the plurality of slit parts is simple and appropriate. Easy to do.
[0014]
The invention described in claim 3 is obtained by adding six or more slit portions to the invention described in claim 1 at substantially equal intervals along the circumferential direction of the mold surface.
[0015]
In the invention according to claim 3, there is no idea of using the die-matching slit as the exhaust function part, and the exhaust function part is mainly composed of the dedicated slit part. Can be set freely, and a constant exhaust capability can be exhibited stably.
[0016]
Moreover, the number of slits is 6 or more so that there is no idea of using the mold matching slit as an exhaust function part, and the exhaust capacity distribution can be obtained as much as possible along the circumferential direction with only the slit part. And a relatively large number.
[0017]
According to a fourth aspect of the invention, in addition to the first aspect of the invention, the slit portion is composed of a plurality of slits arranged close to each other in parallel.
[0018]
In the invention according to the fourth aspect, since one slit portion is constituted by a plurality of slits arranged close to each other in parallel, the exhaust capacity that can be exhibited by one slit portion is freely set in a wide range. Is possible, and machining of the split mold for forming the slit is simplified.
[0019]
The invention according to claim 5 is obtained by adding the slit part to the invention according to claim 1 intermittently along the extending direction in the height direction .
[0020]
In the invention according to claim 5, since the slit portion is constituted by a combination of a plurality of slit portions having a length that is not large along the extending direction in the height direction, the slit portion is formed for the split mold. Is easy to machine.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
The primary blow mold in the double blow molding of the present invention is composed of a combination of a pair of split molds 1 and a single bottom mold 10 as in the prior art. A plurality of slit portions 5 opened and formed over substantially the entire height range of the molding die surface 2 are provided in parallel in the circumferential direction.
[0022]
The slit portion 5 is a portion that exhausts the gas in the molding space of the clamped primary blow mold to the outside of the mold during biaxial stretch blow molding of the preform into the intermediate molded product s. As shown in FIG. 2 and FIG. 3, it is connected to an exhaust hole 6 drilled in advance near the mold surface 2 in the split mold 1.
[0023]
Apart from the slit portion 5, the mold matching slit 4, which is a molding part of the parting line, formed when the two split molds 1 are matched with each other on the mold matching surface 3, is also connected to the gas in the molding space. However, the exhaust capacity exhibited by the mold matching slit 4 is not set to be constant.
[0024]
FIG. 2 shows an example in which the die matching slit 4 is configured to be used as an exhaust function part, and two die matching slits 4 and four slit portions 5 are arranged at substantially equal intervals along the circumferential direction. Thus, the mold matching slit 4 and the slit portion 5 are arranged every 60 degrees of the central angle.
[0025]
In the embodiment shown in FIG. 2, it is necessary to make the exhaust capacity of each slit portion 5 substantially equal to the exhaust capacity exhibited by the mold matching slit 4. The exhaust capacity is not constant and can be accurately set, and the exhaust capacity to be exhibited tends to be small due to the exhaust passage structure formed.
[0026]
For this reason, although the exhaust capacity to be obtained is not large enough, the number of slit parts 5 to be molded can be reduced by the amount by which the mold-matching slit 4 functions as an exhaust function part. The troublesome machining amount for forming the slit portion 5 for the mold 1 is reduced.
[0027]
In FIG. 3, there is no idea to use the die-matching slit 4 as an exhaust function part, and a plurality of slit parts 5 are configured to obtain a desired exhaust capacity, and the exhaust capacity distribution along the circumferential direction is biased as much as possible. 6 or more (six in the illustrated embodiment) are provided on the basis of many experimental results, and each slit portion 5 is substantially equidistant along the circumferential direction ( (Center angle 60 degree intervals).
[0028]
In the embodiment shown in FIG. 3, the exhaust capacity of each slit portion 5 can be accurately set to a desired size without being restricted by the exhaust capacity exhibited by the mold matching slit 4. The required exhaust capacity can be obtained with certainty.
[0029]
In addition, although each slit part 5 is arrange | positioned at substantially equal intervals along the circumferential direction, it displaced 30 degrees of center angles from the type | mold matching slit 4 located in the same position as the conventional straight line ai shown in FIG. When one of the slit portions 5 is positioned at a position (the die-matching slit 4 is positioned at an intermediate point between the adjacent slit portions 5), heat shrinkage generated in the body portion s1 of the formed intermediate molded product s. The deformation exhibited very high uniformity along the circumferential direction.
[0030]
FIG. 4 is an enlarged plan sectional view showing an essential part of an example of the forming means for the slit portion 5, and is formed on the forming die surface 2 of the split die 1 with a wide vertical groove-like recess that is easy to machine. 7, and in a state where a part of the mold surface 2 is formed by the fixing bolt 9 in the groove-like recess 7, the mold piece 8 is fixedly fitted and fixed, A pair of left and right slits are formed between the mold piece 8 to form the slit portion 5, and the exhaust hole 6 is formed in the groove-like recess 7.
[0031]
This embodiment shown in FIG. 4 has a slit with the same width much more than the difficulty of machining by directly cutting and forming a 0.05 to 0.1 mm slit on the mold surface 2 of the split mold 1. It can be molded by simple machining, and as shown in FIG. 5, the formed slit portion 5 is composed of two parallel slits, so that a large exhaust capacity can be stably and reliably exhibited. it can.
[0032]
6 and 7 show the entire front surface of the intermediate molded product s biaxially stretch blow molded using the embodiment shown in FIG. 5 and the plane cross section of the body s1. The heat shrink deformation that occurs is generated in the shoulder portion and the bottom portion having a large thickness substantially in the same manner as the conventional example shown in FIG. 8, but occurs substantially uniformly in the body portion s1, and as shown in FIG. The trunk portion s1 has a flat cross-sectional shape that maintains its circular shape substantially accurately.
[0033]
In addition, since each slit portion 5 is located on the molding die surface 2 in the same manner as the die-matching slit 4 that forms the parting line, the surface portion of the intermediate molded product s facing each slit portion 5 has a parting A line-shaped slit portion mark 5 ′ is formed, and this slit portion mark 5 ′ is formed as it is on the surface of the container S, which is the final molded product.
[0034]
In the embodiment shown in FIGS. 1 and 5, each slit portion 5 has a continuous structure over its entire length, but the center of the body portion s1 of the intermediate molded product s, which is a molding object. In the case where the circumferential groove is formed, each slit portion 5 may be configured in an intermittent structure as necessary or appropriately, such as by intermittently connecting each slit portion 5 at a portion facing the circumferential groove. .
[0035]
【The invention's effect】
Since the present invention has the above-described configuration, the following effects can be obtained.
According to the first aspect of the present invention, the plurality of slit portions forming the exhaust port are arranged in parallel so as to reduce the deviation as much as possible in the exhaust capacity distribution along the circumferential direction of the mold surface of the split mold. Since it is arranged, the influence of the exhaust on the body part of the intermediate molded product to be biaxially stretch blow-molded can be made less biased along the circumferential direction, thereby generating in the body part of the intermediate molded product. The heat shrink deformation can be made substantially uniform along the circumferential direction, and the occurrence of uneven thickness in the finished container can be greatly suppressed.
[0036]
Moreover, since it is the structure which provided only the some slit part in the cutting shape in the shaping | molding die surface of a pair of split mold, implementation is easy regardless of the existing and new installation of a split mold.
[0037]
According to the second aspect of the present invention, since the die-matching slit is used as an exhaust function part, the number of slits processed can be reduced, thereby reducing the labor of machining the slit part with respect to the split mold. Can be reduced.
[0038]
According to the third aspect of the present invention, since six or more slit portions that can exhibit the desired exhaust capability are provided along the circumferential direction of the mold surface of the split mold, Sufficient exhaust capacity can be made to act substantially uniformly.
[0039]
According to the fourth aspect of the present invention, it is possible to easily achieve machining forming of the slit portion with respect to the mold surface of the split mold, and it is possible to easily obtain a desired exhaust capacity.
[0040]
According to the invention described in claim 5, it is possible to simplify the machining operation of the slit portion with respect to the mold surface of the split mold.
[Brief description of the drawings]
FIG. 1 is an overall front view of a combination of one split mold and a bottom mold, showing an embodiment of the present invention.
2 is a fragmentary plan cross-sectional view of the embodiment shown in FIG. 1 in a clamped state. FIG.
FIG. 3 is a cross-sectional plan view of a main part in a mold clamping state showing another embodiment of the slit part.
FIG. 4 is an enlarged plan cross-sectional view of a main part showing another embodiment of the slit portion forming structure.
5 is an overall front view of the combination of one split mold and bottom mold in the embodiment shown in FIG. 4; FIG.
6 is an overall front view of an intermediate molded product that has been stretch-molded according to the embodiment shown in FIG. 5. FIG.
7 is a cross-sectional plan view of the body part of the intermediate molded product shown in FIG. 6;
FIG. 8 is an overall front view showing an example of an intermediate molded product molded by a conventional technique.
9 is a cross-sectional plan view of a body portion of the intermediate molded product shown in FIG.
[Explanation of symbols]
1; Split mold 2; Mold surface 3; Mold alignment surface 4; Mold alignment slit 5; Slit portion 5 '; Slit portion trace 6; Exhaust hole 7; Groove-shaped recess 8; Mold piece 9; Bottom mold s; Intermediate molded product s1; Body pi; Parting line position ai; Straight line S;

Claims (5)

In double blow molding, a primary structure composed of a pair of split molds (1) and one bottom mold (10) used to biaxially stretch blow mold an intermediate molded product (s) from a preform. It is a blow mold, and is formed on the mold surface (2) of the split mold (1) over substantially the entire height range along the extending direction in the height direction, and the exhaust of the gas exhaust path in the mold space Double blow molding in which a plurality of slit portions (5) forming the mouth are arranged in parallel so as to minimize the deviation in the exhaust capacity distribution along the circumferential direction of the molding die surface (2). Primary blow mold for equipment.   The plurality of slit portions (5) including a mold matching slit (4) for forming a parting line are arranged at substantially equal intervals along the circumferential direction of the molding die surface (2). Primary blow mold for double blow molding equipment.   The primary blow mold of the double blow molding apparatus according to claim 1, wherein six or more slit portions (5) are arranged at substantially equal intervals along the circumferential direction of the mold surface (2).   The primary blow mold of the double blow molding device according to claim 1, wherein the slit portion (5) is composed of a plurality of slits arranged close to each other in parallel. The primary blow mold of the double blow molding device according to claim 1, 2, 3, or 4, wherein the slit portion (5) is intermittently formed along the extending direction in the height direction .

Images