JP3722622B2 - Molding method of heat-resistant container and its mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molding method and the mold of the heat-resistant container, in particular, relates to a molding method and the mold of the heat-resistant container having improved heat resistance of the raised portion.
[0002]
[Background Art and Problems to be Solved by the Invention]
In general, a thin packaging container made of a synthetic resin called a biaxial stretch blow container has a stretch suitable temperature preform obtained by injection or extrusion molding positioned in a mold, and is a longitudinal direction corresponding to the longitudinal direction of the container. It is obtained by extending in the direction and expanding in the lateral direction by the pressure of the gas blown into the inside.
[0003]
By the way, when producing the material of such a synthetic resin container, for example, a polyester container, the problem is the heat resistance of the container when the contents are filled at a high temperature.
[0004]
Accordingly, a method for forming a heat-resistant container such as Japanese Patent Application Laid-Open No. 8-187768 according to the proposal of the present applicant has been developed.
[0005]
This molding apparatus blow-molds a preform with a primary blow molding die to form a primary molded product, presses the primary molded product from the inside, contacts the heat treatment mold inner surface, heat-treats, and then performs intermediate heat treatment. It is an epoch-making thing that high crystallinity and low residual stress of the container can be achieved in a short time by blow-molding the product into the shape of the final molded product in a heated final blow-molding die.
[0006]
However, further improvements have been required for the heat resistance of the bottom.
[0007]
That is, the current problem is that, firstly, if the raised bottom portion excluding the top portion is not sufficiently stretched, it is deformed by the temperature and load of the high temperature contents.
[0008]
Secondly, even when the raised bottom portion is sufficiently stretched, deformation at the time of filling the high-temperature contents may become remarkable due to some eccentricity of the top portion of the low stretch.
[0009]
Thirdly, in a molding apparatus such as JP-A-8-187768, for example, as shown in FIG. 6, the raised bottom mold 10 of the final blow molding mold is in a state in which a plurality of step portions 12 are formed on concentric circles. In the case where the intermediate molded product shrunk by heat treatment is tilted and eccentric, the raised bottom mold of the final blow mold cannot be moved smoothly by the stepped portion 12 formed on the raised bottom of the intermediate molded product, The influence of the eccentricity is left on the raised bottom of the final container, resulting in an uneven thickness distribution in the circumferential direction, leading to a decrease in heat resistance.
[0010]
An object of the present invention is to sufficiently extend the raised bottom portion excluding the top portion to prevent changes due to the temperature and load of the high temperature contents of the raised bottom portion.
[0011]
Another object of the present invention is to make the stretched state around the top of the raised bottom part uniform so that stable moldability can be obtained.
[0012]
Still another object of the present invention is to improve the heat resistance of the raised bottom by reliably preventing the eccentricity of the intermediate molded product when blow molding the intermediate molded product after the heat treatment.
[0013]
[Means for Solving the Problems]
In order to achieve the object, the heat-resistant container molding method according to claim 1 is a heat-resistant container molding method in which a primary blow-molded product is heat-treated and contracted, and the intermediate molded product after contraction is blow-molded into a final container.
The primary blow-molded product and the final container have a mountain-shaped raised bottom,
The raised portion is blown with the mountain shape of the raised type which projects into the container inwardly of the same shape,
Each raised bottom type, possess a top portion and a peripheral inclined surface portion formed to be curved inward of smooth the raised bottom mold toward the skirt portion from the top portion,
The top portion is formed by being gradually recessed inward of the raised bottom mold from the outer peripheral side to the center side of the top portion .
[0014]
According to the present invention, the transition part from the top part to the slope part is formed by reversing and bending, so that the peripheral part of the top part, that is, the top part that is not stretched at the transition part that is reversed and bent, and the slope part that is stretched are clear. It is divided into. Furthermore, since the slope portion is recessed inward, it is sufficiently stretched. Therefore, it is possible to make the stretched state in the circumferential direction of the slope part always uniform by being clearly divided into the part that is not drawn and the part that is not stretched, and the heat resistance is improved because the slope part is sufficiently stretched. improves.
[0015]
The primary blow-molded article and final containers are blow molded using a raised bottom mold of the same shape, moreover, the raised bottom of the primary blow-molded article is the same shape as the raised bottom mold in the final container, shrinking the heat treatment Even if the raised bottom of the intermediate molded product is off-centered, the intermediate molded product can be smoothly smoothed even if the sloped surface that curves smoothly inwardly of the raised bottom of the intermediate molded product abuts the top peripheral edge of the raised bottom mold of the final container. Can be corrected, and heat resistance is not lowered.
[0016]
[0017]
Furthermore, since the top is recessed, it will be more clearly inverted and bent at the periphery of the top, and the transition from the unstretched top to the slope will be clear, and the heat resistance at the transition will be There is no half-stretched low stretch region with low properties. Furthermore, the extending | stretching state in the circumferential direction of a slope part can be made uniform.
[0018]
According to a second aspect of the invention, Oite to claim 1,
The raised bottom mold, the top side is the steepest slope, characterized in that it has a slope portion which becomes gradually gentle slope toward the front Kisuso side.
[0019]
According to the present invention, in addition to the state of claim 1 , the slope portion has the steepest slope on the top side and gradually slopes toward the skirt side. The raised bottom can be centered more reliably.
[0020]
Moreover, the stretched state of the slope portion of the raised bottom portion can be further enhanced by the steepest slope on the top side.
[0021]
According to a third aspect of the invention, according to claim 1,
Before SL inclined surface, the is the top side of the steepest slope is gradually gentle slope toward the skirt portion,
The raised bottom is formed at the bottom of the container, the top being thick and the surrounding slope being elongated.
[0022]
According to the present invention, since the oblique face of the raised bottom molds are in a state smoothly curved inwardly, upon blow molding of the primary blow-molded article, clearly will be inverted bent inclined surface at the periphery of the top, The transition from the top portion that is not stretched to the inclined portion that is stretched becomes clear, and there is no half-stretched low stretch region with low heat resistance at the transition portion.
[0023]
In particular, the stretched state of the slope portion of the raised bottom portion is further enhanced by the steepest slope portion on the top side of the steep slope portion.
[0024]
And the extending | stretching state in the circumferential direction of a slope part can be made uniform, and stability of shaping | molding can be improved.
[0025]
The mold according to claim 4 is a mold having a raised bottom mold that forms a mountain-shaped raised bottom portion projecting inwardly into the container at the bottom of the container by blow molding.
The raised bottom mold has a top portion and a slope portion inclined from a peripheral edge of the top portion toward a skirt portion,
Said top portion, characterized in that it is formed in the bottom diameter and the same size of the preform.
[0026]
According to the present invention, by forming the top of the raised bottom mold in the bottom diameter and the same size of the preform, it will be reversed bending the slope portion more clearly in the periphery of the top portion, extending from the top which is not stretched The transition to the slope portion to be made becomes clearer, and a halfway low stretch region with low heat resistance at the transition portion can be eliminated. In addition, the peripheral portion of the top portion can be given heat resistance by uniform and sufficient stretching in the circumferential direction, and the moldability can be stabilized.
[0027]
The invention according to claim 5 is the invention according to claim 4 ,
The top portion is characterized in that the entire top portion is formed by being gradually dented inward of the raised bottom mold from the outer peripheral side to the center side.
[0028]
According to the present invention, in addition to the state of claim 4 , since the top is recessed, at the periphery of the top, it is more clearly inverted and bent to the slope, and from the top that is not stretched to the slope that is stretched Transition becomes clear, and there is no half-stretched low stretch region with low heat resistance at the transition portion, and the stretched state in the circumferential direction of the slope portion can be made more uniform.
[0029]
The invention according to claim 6 is the invention according to claim 4 or 5 ,
The inclined surface portion is formed to be smoothly curved from the periphery of the top portion toward the skirt portion and inside the raised bottom mold.
[0030]
According to the present invention, in addition to the state of claim 4 or 5 , when the slope portion of the raised bottom portion is molded by smoothly raising the slope portion to the inside of the bottom die, the slope portion is brought into contact with the raised bottom die halfway. And sufficient stretching can be performed.
[0031]
The invention according to claim 7 is the invention according to claim 6 ,
The inclined surface portion, the is the top side of the steepest slope, characterized in that it is gradually gentle slope towards the skirt portion.
[0032]
According to the present invention, in addition to the state of claim 6 , the steepest slope portion of the slope portion can further extend sufficiently.
[0033]
[0034]
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0036]
1-5 is a figure which shows the shaping | molding method of the heat-resistant container which concerns on one embodiment of this invention.
[0037]
In this heat-resistant container molding method, for example, as disclosed in JP-A-8-187768, a preform molded using an injection molding machine provided elsewhere is heated to a suitable temperature for stretching, The preform is formed into a primary blow molded product having a container shape larger than that of the final container, and the primary blow molded product is heat-treated in a heat treatment section to shrink it to a desired shape close to the final container. In the final blow molding section, the final container is blow molded.
[0038]
FIG. 1 shows the state of the primary blow molding part, and FIG. 2 shows the state of the final blow molding part.
[0039]
As shown in FIG. 1, in the primary blow molding unit 20, a preform 24 is blow-molded into the shape of a primary blow-molded product using a primary blow molding die 22.
[0040]
The preform 24 has a bottomed cylindrical shape having a neck portion 26, a body portion 28, and a bottom portion 30, and is conveyed in an inverted state in which the neck portion 26 is inserted into the holding portion 34 of the conveying member 32. It has become so.
[0041]
The conveying member 32 is configured such that a stretching rod (not shown) can be inserted into the preform 24 and blow air can be supplied into the preform 24.
[0042]
The primary blow mold 22 includes a primary blow cavity mold 38 having a cavity surface 36 corresponding to the outer shape of the primary blow molded article, a neck guide 40 for holding the outer surface of the neck portion 26 of the preform 24, and a primary blow molded article. A raised bottom mold 42 is formed on the bottom to form a raised bottom.
[0043]
The primary blow cavity mold 38 is in a split shape with the parting surface 44 as a boundary, and a cooling water channel 46 is formed in each split die, and cooling water is supplied into the cooling water channel 46. By this, it is cooled.
[0044]
The neck guide 40 has a divided shape attached to each split mold of the primary blow cavity mold 38.
[0045]
The raised bottom mold 42 can be moved up and down with respect to the primary blow cavity mold 38, and a cooling water channel 48 is formed therein so that it can be cooled in the same manner as the primary blow cavity mold 38.
[0046]
Further, as shown in FIG. 4, the raised bottom mold 42 is formed in a mountain shape protruding inward of the container, and has a top portion 50 and a slope portion 52 formed around the top portion 50. .
[0047]
The top 50 has a substantially circular shape and is formed so as to be gradually recessed inward of the bottom mold 42 from the outer peripheral side to the center side.
[0048]
The top 50 is preferably approximately the same size as the diameter of the bottom 30 of the preform 24. This is because the bottom portion 30 of the preform 24 is usually a portion that is difficult to be stretched. By forming the top portion 50 in the same size as the bottom portion 30 of the preform 24, the portion that is difficult to stretch is stretched almost as it is. It is possible to keep the top portion 50 without being stretched and reliably perform the stretch molding from the slope portion 52.
[0049]
The slope portion 52 is formed to be smoothly raised from the periphery of the top portion 50 toward the skirt portion 53 and curved inside the bottom mold 42.
[0050]
Specifically, as shown in FIG. 4, the slope portion 52 has a steep slope portion 54 having the steepest slope near the top, and the first gentle slope portion 56 connected to the steep slope portion 54, A second gentle slope portion 58 that is continuous with the first gentle slope portion 54, and is curved inward of the raised bottom mold 42 so that the slope portion 52 is within 45 ° with respect to the longitudinal axis X. Is done.
[0051]
The steep slope portion 54 is formed with a straight cross section, and may be set to 20 ° or less with respect to the vertical axis X.
[0052]
Thus, by setting the steep slope portion 54 to 20 ° or less with respect to the vertical axis X, it is possible to sufficiently stretch the periphery of the top portion 50 when the preform 24 is stretched.
[0053]
The first gentle slope portion 56 is formed with a cross-sectional curve, and the second gentle slope portion 58 is formed with a straight cross-section, and has a gentler slope than the second gentle slope portion 56, so that The yarn extends to the position 59 (see FIG. 5).
[0054]
Further, between the top 50 and the steep slope portion 54, an edge portion 60 is formed that is inverted and bent so as to prevent the meat of the preform 24 of the top portion 50 from turning around to the slope portion 52 side.
[0055]
This edge part 60 can fully extend the slope part side by preventing the preform 24 of the top part 50 from turning around to the slope part 52 side.
[0056]
When forming, the preform 24 is conveyed into the primary blow molding part 20 by the conveying member 32, and the primary blow cavity mold 38 of the primary blow mold 22 is clamped, and the neck guide 40 performs the preform. The raised bottom mold 42 is lowered while guiding the outer periphery of the neck portion 26 of the 24, and the mold is clamped with the primary blow cavity mold 38.
[0057]
In this state, a stretching rod is inserted into the preform 24 from the conveying member 32 to stretch the preform 24 in the vertical axis direction, and blow air is supplied into the preform 24 so that the preform 24 is moved in the horizontal axis direction. Stretch.
[0058]
Thus, the preform 24 can be brought into the shape of the primary blow-molded product by bringing the cavity surface 36 of the primary blow cavity mold 38 and the raised bottom mold 42 into close contact with the top 50 and the slope 52.
[0059]
In this case, in the raised bottom mold 42, the diameter of the top 50 is substantially the same as the diameter of the bottom 30 of the preform 24, and hemispherical from the edge 60 as in the shape of the bottom 30 of the preform 24. Since it is formed so as to be recessed, most of the meat of the bottom portion 30 of the preform 24 is accumulated in the top portion 50, and the body portion 28 where the preform 24 is easily extended is extended from the edge portion 60 to the slope portion 52.
[0060]
Furthermore, since the edge portion 60 is formed on the outer periphery of the top portion 50 so as to face slightly upward, the bottom portion 30 is prevented from turning around the inclined portion 52 side of the raised bottom mold 42, and the stretched portion and the non-stretched portion are not stretched. The part is clearly divided at the edge 60.
[0061]
In addition, since the slope portion 52 continues from the steep slope portion 54 to the first gentle slope portion 56 and the second gentle slope portion 58, the meat around the bottom 30 of the preform 24 contacts the other portions in the steep slope portion 54. Without stretching, and can be sufficiently stretched, uniform in the circumferential direction, and sufficiently stretched.
[0062]
In this way, after forming the primary blow-molded product, the primary blow cavity mold 38 and the raised bottom mold 42 are released, and the primary blow-molded product is transported to the heat treatment section by the transport member 32.
[0063]
In the heat treatment section, although not shown, heat treatment is performed on the primary blow-molded product using a heat treatment mold having substantially the same structure as the primary blow mold 22.
[0064]
In this heat treatment mold, the primary blow-molded product can be heated by circulating a heat medium or attaching a heater in place of the cooling water channels 46 and 48 in FIG.
[0065]
In the heat treatment section, blow air is supplied from the conveying member 32 into the primary blow-molded product, and the outer surface of the primary blow-molded product is pressed and adhered to the heat treatment mold to increase the crystallinity and low residual stress of the container. Like to do.
[0066]
The primary blow-molded product that has been heat-treated by this heat-treatment part shrinks by opening the heat-treatment mold, and becomes an intermediate molded product 62 that is smaller than the diameter of the final container and slightly higher in overall height.
[0067]
In this state, as shown in FIGS. 2 and 3, a raised bottom portion 78 protruding inward of the container is formed at the bottom of the intermediate molded product 62, as in the case of the primary blow molded product.
[0068]
The raised bottom portion 78 has a thick-walled top portion 84 that is not stretched, and a stretched slope portion 86 that swells and curves smoothly from the peripheral edge of the top portion 84 toward the skirt portion 88 toward the opposite side. .
[0069]
The slope portion 86 includes a steep slope portion 90 having a straight cross-sectional shape with the steepest slope toward the top portion 84 corresponding to the slope portion 52 of the raised bottom mold 72, and a first gentle slope surface 92 having a curved cross-section connected thereto. In addition, a second gentle slope portion 94 having a linear cross section continuous with the second gentle slope portion 94 is provided.
[0070]
Then, the intermediate molded product 62 is conveyed by the conveying member 32 to the final blow molding unit 64 shown in FIG.
[0071]
In the final blow molding unit 64, final blow molding is performed using the final blow molding die 66.
[0072]
The final blow mold 66 includes a final blow cavity mold 68, a neck guide 70, and a raised bottom mold 72.
[0073]
The final blow cavity mold 68 has the same configuration as the primary blow cavity mold 68 except that the cavity surface 74 has a shape substantially corresponding to the shape of the final container 76 (see FIG. 5).
[0074]
The neck guide 70 has the same configuration as the primary blow molding die 22.
[0075]
The raised bottom mold 72 has substantially the same shape as the raised bottom mold 42 in the primary blow molding mold 22 and has the same configuration. Therefore, here, each part has the same reference numerals used in the description of the primary blow molding mold 22. The structure of is shown.
[0076]
In order to perform final blow molding of the intermediate molded product 62 using the final blow molding die 66 having such a configuration, the final blow molding is performed in a state where the intermediate molded product 62 is conveyed to the final blow molded portion 64 by the conveying member 32. The cavity mold 68 is clamped and the outer periphery of the neck portion 26 is guided by the neck guide 70.
[0077]
In this state, as shown in FIG. 3 (1), the intermediate molded product 62 is slightly inclined due to the difference in the degree of contraction in the circumferential direction, and the core position Y of the raised bottom portion 78 is higher than the core position Z of the raised bottom mold 72. Even in a slightly eccentric state, the eccentric state is slightly corrected by lowering the raised bottom mold 72, for example, with the raised bottom mold 72 lowered halfway as shown in FIG. When the raised bottom mold 72 is further lowered to the mold clamping position, the eccentric state of the raised bottom 78 is completely corrected as shown in FIG.
[0078]
That is, by simply lowering the raised bottom mold 72, the raised bottom portion 78 is automatically aligned. In this state, blow air is supplied from the conveying member 32 into the intermediate molded product 62, and the outer surface of the intermediate molded product 62 is detected. Is brought into close contact with the cavity surface 74 of the final blow cavity mold 68 and the top 50 and the slope 52 of the raised bottom mold 72, the final container 76 is formed.
[0079]
In this case, the steep slope portion 54 of the raised bottom mold 72 serves as a guide for automatic alignment, and since the slope portion 52 is continuously formed flat in the axial direction, it is caught on the raised bottom portion 78 of the intermediate formed product 62 on the way. This makes it possible to perform automatic alignment without fail.
[0080]
As described above, by enabling the raised bottom portion 78 of the intermediate molded product 62 to be automatically aligned, it is possible to improve the heat resistance without leaving the influence of the eccentricity on the raised bottom portion 72 of the final container 76.
[0081]
As shown in FIG. 5, the final container 76 formed in this way is thick at the top portion 84 of the raised bottom portion 82 formed at the bottom portion 80 and is not stretched, and the slope portion 86 is on the opposite side. It is in a swelled state and is in a state of being thin and sufficiently stretched.
[0082]
The slope portion 86 includes a steep slope portion 90 having a straight cross-sectional shape with the steepest slope toward the top portion 84 corresponding to the slope portion 52 of the raised bottom mold 72, and a first gentle slope surface 92 having a curved cross-section connected thereto. In addition, a second gentle slope portion 94 having a linear cross section continuous with the second gentle slope portion 94 is provided.
[0083]
Accordingly, the top portion 84 is made thick to have heat resistance, and the slope portion 86 has heat resistance by stretching, so that the raised bottom portion 82 which is difficult to have heat resistance can be made heat resistant under conditions according to the conditions of each portion. It is possible to prevent the deformation of the raised bottom portion 82 due to the temperature and load of the high-temperature contents.
[0084]
The present invention is not limited to the embodiment described above, and can be modified into various forms within the scope of the gist of the present invention.
[0085]
For example, although the shape of the top portion of the raised bottom portion is in a state where the center side is recessed, the shape is not limited to this example, and a substantially flat state may be possible.
[0086]
Moreover, although the steep slope part and the 2nd gentle slope part of the slope part were each formed in linear form, it is also possible to form these in curvilinear form.
[0087]
Alternatively, in this example, the primary blow-molded product was heat-treated by the heat treatment mold, but the heat treatment mold may be omitted by introducing a heat treatment medium into the primary blow mold, but the molding cycle and molding stability are improved. Damaged.
[0088]
Alternatively, it is possible to appropriately use a method of heating a primary blow molded product in a hot air furnace, a method of heating with an infrared heater, microwave heating, or the like without using a heat treatment mold.
[0089]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state of a primary blow molded part according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a state of a final blow molded part according to one embodiment of the present invention.
FIGS. 3 (1), (2) and (3) are partial cross-sectional views showing a self-aligning state of an intermediate molding part by processing a raised bottom mold in the final blow molding part of FIG.
FIG. 4 is a partial sectional view of a raised bottom mold.
FIG. 5 is a partial cross-sectional view of the bottom of the final container.
FIG. 6 is a cross-sectional view showing a part of a conventional raised bottom mold.
[Explanation of symbols]
20 Primary blow molding portion 22 Primary blow molding die 24 Preform 30 Preform bottom portion 42, 72 Raised bottom die 50 Raised bottom die top portion 52 Raised bottom die slope view 54 Raised bottom die steep slope portion 60 Edge portion 62 Intermediate molding 64 Final blow Molding part 66 Final blow mold 76 Final container 78 Raised bottom part 80 of intermediate molded product Final container bottom part 82 Final container raised bottom part 84 Final container raised bottom part top part 86 Final container raised bottom part slope part

Claims (7)

In the heat-resistant container molding method in which the primary blow-molded product is contracted by heat treatment, and the intermediate molded product after contraction is blow-molded into the final container,
The primary blow-molded product and the final container have a mountain-shaped raised bottom,
The raised portion is blown with the mountain shape of the raised type which projects into the container inwardly of the same shape,
Each raised bottom type, possess a top portion and a peripheral inclined surface portion formed to be curved inward of smooth the raised bottom mold toward the skirt portion from the top portion,
The method for forming a heat-resistant container, wherein the top portion is formed by being gradually dented inward of the raised bottom mold from the outer peripheral side to the center side of the top portion . Oite to claim 1,
The raised bottom molds, the is the top side of the steepest slope, method of molding a heat-resistant container, characterized in that it comprises a front Kisuso portion inclined surface which becomes progressively gentle slope toward the side. In claim 1,
Before SL inclined surface, the is the top side of the steepest slope is gradually gentle slope toward the skirt portion,
A method for forming a heat-resistant container, characterized in that the raised bottom portion is formed on the bottom portion of the container, the top portion being thick and the surrounding slope portion being extended. In a mold having a raised bottom mold that forms a mountain-shaped raised bottom part protruding inward of the container at the bottom of the container by blow molding,
The raised bottom mold has a top portion and a slope portion inclined from a peripheral edge of the top portion toward a skirt portion,
Said top portion, a mold, characterized in that it is formed in the bottom diameter and the same size of the preform. In claim 4 ,
The mold is characterized in that the top part is formed so as to be gradually recessed inward of the raised bottom mold from the outer peripheral side to the center side. In claim 4 or 5 ,
The mold is characterized in that the inclined surface portion is smoothly curved from the periphery of the top portion toward the skirt portion and is curved inward of the raised bottom mold. In claim 6 ,
The inclined surface portion, the is the top side of the steepest slope, mold, characterized in that it is gradually gentle slope towards the skirt portion.

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