JP2001510410A - Blow molding plastic container manufacturing process - Google Patents

Abstract

(57) Abstract: A blow-molded plastic container and a process for producing the same, wherein the container has a support member in a hollow portion of the container, the support member extending completely across the hollow portion to form a container body. And supports the inner surface of the wall at two places separated by a distance. The shape of the container is changed in areas of stress concentration, thus preventing stress concentration and excessive deformation in that area.

Description

DETAILED DESCRIPTION OF THE INVENTION Manufacturing Process of Blow Molded Plastic Container Background of the Invention The invention is particularly concerned with plastic containers for containing carbonated beverages and other pressurized liquids and their manufacture. These containers are usually manufactured by blow molding a preform made by injection molding or extrusion into a suitably shaped container using a blow mold having the desired shape. The commonly used thermoplastic materials are polyethylene terephthalate (PET), polyolefin and the like, but other materials may be used. The shape of the container generally comprises a neck having a cap retaining means, a shoulder extending from the neck, a side wall or body extending from the shoulder, and a bottom extending from the side wall connected to the side wall. The size of the container has been demanded to be large for convenience and economy. For example, there are 2 liter PET bottles and 1 gallon milk bottles that are widely used for carbonated beverages. It is desirable to make these containers larger. For carbonated drinks, it is preferable to keep the carbon dioxide gas in a dissolved state. However, if these containers are used for carbonated drinks, carbonic acid is considerably released. This loss occurs when the container is repeatedly opened, as is often the case in containers that have a larger capacity than is consumed in a single opening. One time CO _Two The loss is called headspace loss. "Headspace" refers to the volume of the container portion not filled with beverage, _Two Escapes into this volume. The headspace increases as the volume of beverage in the container is repeatedly consumed from the same container and decreases. Headspace loss is the reason why the size of carbonated beverage containers is generally limited to 2 liters. There are also 3 liter containers, which are used especially at high consumption rates, such as in outdoor groups. In addition, large containers, such as bottles of 1.5 liters or more, are cumbersome for people with small hands, especially children. Therefore, there is a need for a more convenient handling method for such people, which does not require grasping with both hands to pour. Two disadvantages of such a large container are eliminated by providing a built-in interior wall therein. For large bottles, such interior walls partition the bottle into several rooms and correspondingly only one room can be opened at a time, so that one room at a time Can only be consumed from. Of course, to achieve such sequential consumption, the bottle must be designed to be selectively closed. An example of a compartmented container is shown in U.S. Patent No. 5,232,108 to Y. NAKAMURA. A handle with integrated reinforcement may be incorporated to improve the handling of large containers. That is, an inner wall member may be attached to the recess on the inner surface of the container so that the recess forming the handle as described in US Pat. No. 5,398,828 is not inverted by internal pressure. Thus, the built-in interior wall can be used for two purposes. One is to subdivide the container, and the other is to prevent the inversion of the concave portion of the outer wall of the container, that is, to prevent the concave portion from protruding in the opposite direction. It is an object of the present invention to provide an economical and aesthetic bottle made of PET or other materials with comparable moldability, such as polycarbonate, polystyrene and the like, which bottle may have several rooms and / or It may have a handle which forms part of the side wall, said side wall being deformed in a predetermined manner by the internal pressure and the handle does not turn over even if the handle is used. Attempts have been made in the past to achieve this goal. For example, according to the above-mentioned U.S. Pat. No. 5,232,108, a preform is prepared and blown into a mold having a molding lumen corresponding to the dimensions of the desired final container. The problem with this lies in the way the blow molded container is deformed when it is deformed by the internal pressure generated by the carbonated beverage. Due to the internal wall constraints, no one can deform in the same way. If this deformation is too great, the appearance of a bottle filled with liquid and pressurized will be unacceptable to the consumer purchasing the beverage. In the case of the above-mentioned bottle with a handle, there is a possibility that the handle is deformed so as not to withstand practical use. Such drawbacks may be theoretically eliminated by increasing the rigidity of the container being molded. To do so, the wall thickness may be increased as necessary, but this is not preferred because it increases the amount of plastic used to manufacture the container and consequently increases costs. Also, in the case of crystalline plastics such as polyethylene terephthalate (PET), polycarbonate (PC), or nylon, thickening the walls results in structurally undesirable crystalline forms. Accordingly, a first object of the present invention is to provide blow-molded plastics for pressurized contents, especially for carbonated beverages, having improved shape and / or size over those currently available. To provide a container and its manufacturing process. It is another object of the present invention to provide such a container and manufacturing process that does not result in undesirable crystalline morphology or unduly increase the cost of the plastic raw material in its manufacture. Still another object of the present invention is to provide the above-described container and manufacturing process, wherein when the container is provided with a handle portion, the handle portion does not lose its usefulness even if the container is filled with carbonated beverage or the like under pressure. It is to be. It is yet another object of the present invention to provide a method of manufacturing a container having an interior chamber formed by a support wall and means for predetermining the final shape of the container when an internal pressure is applied. Other objects and advantages of the present invention will become apparent hereinafter. Summary of the Invention According to the present invention, the above objects and advantages are easily obtained. The present invention provides an improved method of forming a blow molded container having an internal member for a pressurized liquid. The container has an outer wall having an inner surface and an outer surface, and the inner member is connected to an inner surface of the outer wall at an intersection between the two, and the shape of the container when molded is the same as the shape when pressed. Are different, and the change to the latter by pressurization is predictable. The present invention also provides an improved process for blow molding a carbonated beverage container, the process having an outer wall having an inner surface and an outer surface, wherein the inner wall member is connected to the inner surface of the outer wall. Providing a plastic precursor (precursor), that is, a plastic container semi-finished product, determining its stress-strain properties, and further determining its shape under pressure, based on these properties and determination, Calculating whether a similar container semi-finished product will deform to the desired shape when pressurized, creating the same container semi-finished product described above, and applying a specific internal pressure to the similar container semi-finished product described above. To produce a second container having a predetermined shape. The container of the present invention offers many advantages. It is a blow-molded, partitioned plastic container having at least one internal wall and may have a supported handle, wherein the container fills a carbonated beverage or the like under pressure. Only then can it take its final shape and become suitable for use. The container of the present invention is convenient, easily made in an industrial manner, and reduces the problem of unwanted deformation without unduly increasing the weight of the container. According to the present invention there is provided a molding process for blow molded containers for carbonated beverages, the molding process having an shape and wall thickness, an outer wall having an inner surface and an outer surface, and connecting to an inner surface of the outer wall. Providing a blow-molded plastic semi-finished product having an internal wall member, and mechanical properties at selected locations of the semi-finished product, and the internal pressure in the semi-finished product due to internal pressure in the vicinity of said location. Determining a stress distribution and modifying at least one wall thickness and shape to create a modified semi-finished body, wherein the stress under internal pressure provides a desired manner of deformation; Thus, a desired blow-molded plastic container is obtained. Preferably, in the altering step, the stress distribution is reduced to within certain limits. Other advantages of the present invention will become clear below. BRIEF DESCRIPTION OF THE FIGURES The foregoing will be more readily understood with reference to the following illustrative drawings, which are as follows. FIG. 1 is a sectional side view of a preform for producing the container of the present invention. FIG. 1A is a cross-sectional view taken along line 1A-1A of FIG. FIG. 2A is a partial perspective view of a core for forming the preform of FIG. FIG. 2B is a cross-sectional view of the core and injection mold assembly for forming the preform of FIG. FIG. 3 is a partial sectional view of a mold for blow-molding the container of the present invention from a preform similar to the preform of FIG. FIG. 4 is an elevation view of the container of the present invention. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4, showing the unfinished container semi-finished product and the container filled with carbonated beverage. FIG. 6 is a partial cross-sectional view of the intersection of the outer and inner walls of the container under internal pressure. FIG. 7 is an enlarged partial cross-sectional view similar to FIG. FIG. 8 is a partial cross-sectional view similar to FIGS. 6 and 7, showing one improvement in accordance with the present invention. Detailed Description of the Preferred Embodiment According to the invention, the container according to the invention has an inner wall forming a partition and / or a recess for facilitating the gripping of the bottle and lobes projecting between the recesses. The preform for forming the container can be made by pressure molding and has at least one internal wall, which extends completely across the interior of the preform. , Which is in a position corresponding to the internal support of the final blown and pressurized container. Referring to FIG. 1, a plastic parison or preform 10 is molded from a resin by pressure molding, preferably from a synthetic resin that can be biaxially stretched, such as polyethylene terephthalate. The preform 10 has a neck 11 defining an opening 12 and may have an external thread 13. This external thread serves as a place for attaching a cap or sealing means, for example a stopper suitable for partial opening, to the final blow molded container. The preform 10 has a body 14 extending from the neck 11 and a bottom 15 extending therefrom and integral therewith. Although the barrel of FIG. 1 is generally cylindrical, it may of course be out of the cylindrical configuration. The neck 11 has an inner wall 11A and an outer wall 11B, the cylindrical body 14 has an inner wall 14A and an outer wall 14B, and the bottom 15 has an inner wall 15A and an outer wall 15B. The body 14 defines a hollow 16 inside the preform 10, which is closed at the bottom 15 and open at the opening 12 in the neck. The bottom 15 may have any desired or convenient shape depending on the properties of the final container desired, for example a hemispherical shape as shown in FIG. 1 or a flat or slightly indented bottom. Well, and may have several feet. The preform 10 has at least one, often more than one, inner wall 17, for example, FIG. 1A shows two walls. The inner wall 17 extends completely across the hollow 16 from the bottom 15 to the cylindrical body 14, preferably ending in the body 14, but if necessary extending to the neck or edge. Is also good. As shown in FIG. 1A, four partitioned rooms 17A, 17B, 17C and 17D are formed by the inner wall 17. Of course, these rooms communicate with each other above the wall 17. Alternatively, the interior wall 17 may be confined to the area of the preform 10 where a handle is subsequently formed, such as in US Pat. No. 5,398,828. As can be clearly seen from FIGS. 1 and 1A, the inner wall 17 is attached to the inner surface 14A of the wall. The preform may be made of transparent PET so that the interior walls are visible. The method of molding the preform 10 by injection molding is shown in FIGS. 2A and 2B. In this case, the injection molding core 20 has a substantially cylindrical outer wall 21 and a slot 22 corresponding to the desired inner wall in the preform. The core 20 is placed in a conventional manner, coaxially with an injection nozzle 24 located in an injection mold 23 adjacent to the bottom 25 of the injection mold core. The core 20 is placed in the injection mold 23 so that a gap 26 is maintained between the core 20 and the injection mold 23, and a molten plastic 27 is filled with the injection nozzle 24 so as to fill the gap 26. Is injected through. Molten plastic 27 also flows into slots 22 of core 20 to form interior wall 17. Alternatively, the inner wall may be formed separately if desired and then glued to the inner surface of the outer wall of the preform or semi-finished product. The injection mold and core assembly is then opened and the preform 10 is removed in a conventional manner. The hot preform 10 is then placed in a blow mold 30 as shown in FIG. 3, while still at a temperature suitable for blow molding, and blown or stretch blow molded from this preform. Thereby, a hollow article serving as a semi-finished product of the container of the present invention is formed. The example shown here is an example of a bottle with a handle. The hot preform is placed in a blow mold having the shape of a semi-finished product of the desired container, such as the blow mold 30 of FIG. 3, and the compressed air is blown into the mold. It expands to a shape 31 corresponding to a semi-finished product, which is indicated by a broken line in FIG. 3, and is stretched in the axial direction and the circumferential direction. This step is performed with or without stretching rods or mandrels to assist in axial stretching. If such a rod is used, the rod will have as many branches as there are chambers of the preform, each branch abutting the bottom of the preform in each room. The wall 17 expands as much as the blow mold 30 allows. The particular blow mold shown in FIG. 3 has an internal shape such as to form a hollow plastic article which is a semi-finished product of the container 40 shown in FIG. The cross section of the lobe, which is the protrusion of the semi-finished product, is indicated by a dotted line in FIG. The mold 30 has at least two adjacent lobes connected by a recess. This is not shown in the cross-sectional view of FIG. 3, but is clearly shown in FIG. In a conventional manner, the mold 30 is split as indicated by the arrow 32 in FIG. 3 to release the blow-molded container semi-finished product. As can be seen from FIG. 5, the outer circumference of the semi-finished product is larger than the circumference of a circle circumscribing it. Therefore, the wall 14 of the preform 10 shown in FIG. 1 is stretched to a greater extent in the region where the recess serving as the handle is formed than in the other regions. In a preferred embodiment, the wall of the preform has a thickening 19 at the intersection of walls 17 and 19, as shown in FIG. 1A. The thickness increasing portion is provided to the portion which becomes the concave portion during the blow molding, and reduces the stress concentration that occurs when the thickness does not increase. The thickness increase may also be provided in the part of the mold that forms the recess, so that excessive thickness reduction is avoided. In this way, a blow molded plastic container 40 is formed, which has a neck 41 defining an opening 42, a bottom 43, and a body 44 connecting the neck 41 and the bottom 43. The neck 41 is provided with an external thread 45 corresponding to the thread 13 of the preform 10 for attaching a plug. The bottom 43 may have a generally conical base 46 facing inwardly on the axis. The container 40 also has a shoulder 47 connecting the neck 41 and the cylindrical body 44. The container 40 has at least one inner wall 50. This inner wall corresponds to the inner wall 17 of the preform 10 and extends completely across the hollow part 51 inside the container 40 and may extend from the bottom part 43 to the body part 44 and optionally also the neck part. It may extend to form a compartmented container. The inner wall (s) may be limited only to the region of the handle. As can be easily seen from FIGS. 3 and 5, the inner wall is integral with the container. The inner wall may extend to the bottom as shown in FIG. 3, or may start and end at the torso as shown in FIG. Alternatively, it may extend to the neck region. Referring to FIG. 5, the body 44 has adjacent arched lobes 60 connected by indented areas or recesses 61, which are particularly suitable as handles for large containers. Of course, other forms may be used. The support member 50 in the hollow portion 51 connects the concave portions to each other, and maintains the space between the concave portions to provide support for preventing the concave portions from being turned upside down. As can be seen from FIG. 4, the inner wall may end in the body near the end of the handle. In the exemplary embodiment shown in FIG. 4, the container 40 has a separate part handle formed by a recess 61 and a lobe 60. A support member 50 is provided adjacent to and supports the recess as described above. The support member may extend to the bottom and may extend into the neck. 4 and 5 show an embodiment of the container 40 of the present invention, which is preferred as a container having a handle. FIG. 5 shows a quasi-finished lobe 52 as produced by blow molding, the boundaries of which are indicated by dashed lines in FIG. The bases of two adjacent depressions or depressions 61 are connected by an internal support member 50 to prevent the lobe from spreading at the intersection of the support member 50 and the depression 61. In the semi-finished container 40, the semi-finished lobe 52 includes an interior wall and a segment 53, the latter being a straight or slightly diverging wall as shown by the dashed lines. And may be connected by arched segments 54. When the container semi-finished product is pressurized, for example, by filling with a carbonated beverage, the segments 53 transform into arcuate segments 55, defining the desired, smaller lobe boundaries. The problem is similar for divider bottles without handle lobes. The pressurized partition bottle expands under the constraint of the inner wall and deforms into an arched bulge between said walls rather than a substantially circular cross-section, which comprises a pressurized bottle. Is desirable as an appearance. The basic object of the present invention is to design a semi-finished product such that the pre-finished product as a pre-stage state of the final container is converted into a desired final container in the stage of pressurization as described above. At this time, the pressure required for the conversion has a desirable effect of giving a desired appearance and performance to the final container. According to the invention, the mechanical properties of the materials used, for example polyethylene terephthalate, in particular the relationship between tensile stress and deformation, are tested by exposure to various conditions of time, temperature and other environments. At this time, a static test and a creep test are performed at several environmental temperatures for some parts of a semi-finished product model that is similar in size and shape to a desired semi-finished product at various locations. The average properties obtained from the literature are not sufficient for this purpose. Important properties of blow molded containers vary from shape to shape and size to size. Its properties depend on the design of the preform from which the container is made, and on the temperature distribution and other variables of the preform during processing. Thus, the stress responsiveness and corresponding deformation of the locations where the semi-finished product is converted to the final container by internal pressure depends on the corresponding stress-strain relationship at each location. In particular, the stress-strain response should be defined under static (rupture) and creep conditions, taking into account the environmental conditions to which the finished container is to be exposed. Starting from the reasonably estimated shape of the semi-finished product, the way of deformation under the same internal pressure as measured in the model semi-finished product is calculated. The data obtained in this way is used to derive the shape of the semi-finished product by a computer design technique known as finite element analysis (FEA). The FEA predicts the shape of the semi-finished product giving the desired final container shape based on the stress-strain information determined as described above. In FEA, the shape of the final container is calculated and, once the desired final dimensions have been reached, the corresponding stress distribution is observed. To achieve this completely, the predicted semi-finished product and the desired container model dimensional data are provided to the FEA. At this time, the properties and the stress-strain relationship of each place of the semi-finished product are taken into consideration. For example, the characteristics of the inner wall 50 are significantly different from the characteristics of the outer wall 44, as are the characteristics of the intersection of these walls and the characteristics of locations far from the intersection. The same is true for the intersection of the wall 50 with the bottom wall, as shown in FIG. 4, and other locations where significant thickness changes occur from the shape of the semi-finished product and the desired final container. It is known to use a computer calculation program, known as FEA, in the structural design of containers under internal pressure, including bottles, primarily for predicting performance under use conditions, for example, for failure analysis. In effect, FEA linearizes a known equation system related to stress and deformation for a particular structure, using coefficients such as the Young's modulus, Poisson's ratio, and creep rate of the material making up the structure. Things. FEA uses the value of the coefficient as a constant in each equation, but the coefficient is used for test samples made from the same material under similar conditions, but independent of any structure similar to the desired final structure. Determined by performing an independent test, for example, a tensile test. The FEA performed in this way is a necessary and important factor for the product and its manufacturing process, as in the case of the product described here, where the complex shape causes a large difference in modulus in the manufacturing process. FEA also reveals where stress concentrations occur as part of the stress distribution. Stress concentrations can cause the desired final container to deform beyond its desired limits, sometimes leading to failure. Stress concentrations occur, for example, where there is an abrupt transition from one wall thickness to another. Therefore, the object of the present invention is to determine the correspondence of the shape between the semi-finished product and the final bottle, as well as the places where stress concentration is likely to occur, for example, rounded corners and large changes in wall thickness. The consideration is to reduce the stress to a level that does not cause excessive strain when the desired container is exposed to internal pressure. 6 to 8 show examples of stress concentration in a location having a shape characteristic that causes excessive stress concentration. FIG. 6 shows the intersection of the inner wall 50 and the outer wall 44 when an internal pressure is applied to the container 40. The expansion force F1 is applied to the inner wall, and the force F2 in the direction of the dashed line is applied to the outer wall. The resulting average stress, except for the point of intersection, corresponds to the average stress taken for each cross-sectional area. At the intersection, the stress will be a superposition of the above average stresses, the magnitude of which depends on several factors, but the important ones are the rounded corners between the two walls and the microstructure at the intersection . The choice of this radius also depends on the design required for the injection mold for the preform. FEA predicts microstructure and maximum stress as a function of radius as described above. Then, taking into account the crystal morphology of the material at each location, preform and bottle forming conditions are selected such that the stress is within an acceptable range. FIG. 7 shows an example of stress concentration caused by the crystal morphology of the preform. It should be noted that the stresses are additive, so that the stress due to rounded corners is in addition to other effects, such as the stress due to the presence of non-uniform crystalline morphology. FIG. 7 shows the same intersection as FIG. 6, but is part of the semi-finished product model. At intersection 70, it can be seen that the substantial cross-sectional area and hence the accumulation of material is greater than at locations 71 and 72. Therefore, the crystal structure 70A in the irregularly enclosed region of FIG. 7 tends to be coarse and spherical over the length of the intersection. This acts as an effective notch for fine crystals in other cross-sections, thus causing stress concentrations. The orientation of the region 70 is different due to a difference in thermal response due to a large mass. This region can be overstretched to cause tears and / or become largely spherical crystals and act as notches. Differences in stretch ratios cause differences in the degree and type of crystals. In this example, this difference is further emphasized by the fact that the temperatures at which the two walls are deformed during blow molding are not the same. The properties of crystalline plastics such as PET strongly depend on the orientation state. If there is a large difference in the orientation state in the same structure, the same effect as a discontinuity such as a notch appears when a stress is applied. Considering specifically at location 70 in FIG. 7, the accumulation of material that is present in the preform, and thus also in the semi-finished product and the final container, is significantly affected by the heating of the preform prior to blow molding. Causes a difference. That is, the region near the region 70 is expected to reach a higher temperature in the same time as compared to the center or the center of the region 70. This obviously affects the way in which the preform and the semi-finished product are deformed and can result in large differences between the preform and / or the corresponding parts of the final container. Again, a notch effect occurs. While FEA is useful in finding dimensional countermeasures to eliminate these notch effects, it must be based on detailed stress-strain data applicable to these problem areas. In general, a good semi-finished product must be provided with a radius of curvature that is sufficient and uniform in thickness, especially at intersections. Also, in the case of PET, attention must be paid to the difference in crystal morphology. FIG. 8 is a cross-sectional view of the same intersection as FIGS. 6 and 7, but illustrates one possibility of the present invention to average the cross-sectional area of the semi-finished product at the intersection. In this case, an outer groove 73 is provided on an outer surface 75 of the outer wall 74 near the intersection of the inner wall 76 and the outer wall 74. The invention is not limited to what has been described or illustrated herein, but is only for describing the best embodiment of the invention. It should be understood that it is easy to change the component arrangement and details of operation. The present invention covers all modifications without departing from the spirit and scope defined in the claims.

[Procedure for Amendment] Article 184-8, Paragraph 1 of the Patent Act [Date of Submission] October 2, 1998 (1998.10.2) [Content of Amendment] Claims 1. A method of molding a blow molded plastic container (40) for a carbonated beverage, the method comprising: forming a shape and wall thickness, having an inner surface and an outer surface, and extending across the inner cavity and the inner cavity; A first blow molded plastic semi-finished product (31) including an outer wall having an inner wall member (50, 76) connecting the first portion and a second portion of the inner surface by blow molding from a preform. Forming; measuring the tensile strength of the semi-finished product against deformation at selected locations; and measuring stress distribution in the first semi-finished product due to internal pressure near the location. Calculating the wall thickness and shape of the modified second blow-molded semi-finished product that deforms to a desired shape under pressure based on the data obtained in the step of performing Complete The adult has an inner surface and an outer surface with a shape and wall thickness, and further includes an inner cavity and an inner wall extending across the inner cavity to connect the first portion of the inner surface and the second portion of the inner surface. And a step of blow molding a second preform to produce the modified second blow molded semi-finished product, wherein the second semi-finished product is formed by blow molding a second preform. At least one of the wall thickness and the shape of the first semi-finished product is changed so that the desired deformation pattern is obtained by the stress when the internal pressure is applied, whereby the desired blow-molded plastic container (40) is formed. ). 2. The method of claim 1, wherein changing at least one of wall thickness and shape is such that stress concentrations are reduced to within certain limits. 3. The method according to claim 1, wherein the measurement of the stress distribution of the semi-finished product under the internal pressure is performed for designing a desired blow molded plastic container. 4. The method according to claim 3, comprising the steps of pressing the first semi-finished product (31) and measuring stress distribution and deformation in the first semi-finished product. 5. The method of claim 4, wherein the stress distribution and the relationship of tensile strength to stress are measured by finite element analysis based on the distribution of properties in the semi-finished product. 6. The groove (73) is provided in a portion of the outer surface of the outer wall (74) of the second semi-finished product adjacent to the intersection of the inner wall member (76) and the outer wall. Process. 7. 7. The method of claim 6, wherein said grooves are designed to provide a substantially uniform crystal morphology at said intersection.

────────────────────────────────────────────────── ─── Continuation of front page    (81) Designated countries EP (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, L U, MC, NL, PT, SE), OA (BF, BJ, CF) , CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, M W, SD, SZ, UG, ZW), EA (AM, AZ, BY) , KG, KZ, MD, RU, TJ, TM), AL, AM , AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, E S, FI, GB, GE, GH, HU, IL, IS, JP , KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, M W, MX, NO, NZ, PL, PT, RO, RU, SD , SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, UZ, VN, YU, ZW

Claims (1)

[Claims]   1. For molding blow molded plastic containers (40) for carbonated beverages Law,   An outer wall having an inner surface and an outer surface having a certain shape and wall thickness, and connected to the inner surface of the outer wall -Molded plastic semi-finished with internal wall members (50, 76) Prepare body (31),   The mechanical properties of selected locations of this semi-finished product and the proximity of these locations Measure the stress distribution in the semi-finished product due to the internal pressure nearby,   In order to obtain the desired way of deformation by the stress when the internal pressure is applied, By changing at least one of the wall thickness and shape of the semi-finished product, A finished body is produced, and the desired blow molded plastic container (40 ).   2. The altering step is such that stress concentrations are reduced to within certain limits. The method of claim 1 wherein the method is performed.   3. The measurement of the stress distribution under the internal pressure of the semi-finished product is performed by a desired blow molding. 2. The method according to claim 1, which is performed for designing a plastic container. Method.   4. Semi-finished product approximating the desired blow molded plastic container (40) (31) is prepared, and the semi-finished product (31) is pressurized to generate a stress in the semi-finished product. 4. The method according to claim 3, wherein the distribution and the deformation are measured.   5. Stress and deformation properties are based on the distribution of properties in the semi-finished product. 5. The method of claim 4, wherein the method is measured by a finite element analysis.   6. Grooves (73) are formed in the outer surface of the outer wall (74) adjacent to the intersection of the inner wall (76) and the outer wall. The process according to claim 1, comprising providing   7. The grooves may provide a substantially uniform crystal morphology at the intersection. 7. The method according to claim 6, wherein the method is designed to: