JP2017013252A - Method for heating pre-formed body, bottomed cylindrical container and pre-formed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of producing a bottomed container by suitably heating a pre-formed body without causing thermal deformation and performing biaxial drawing blow forming.SOLUTION: A preform 10 as a planar pre-formed body provided with: a planar body part 12 to be formed into the container body part of a bottomed container by being subjected to biaxial drawing blow forming; and an edge part flange 13 to be formed into the mouth part flange of the bottomed container not being subjected to biaxial drawing blow forming is used. By conveying the planar body part 12 of the preform 10 in a state of being held by heating faces 31a, 32a of upper and lower heating elements 31, 32, contact heating is performed, the planar body part 12 is heated to a temperature at which biaxial drawing forming is possible, and thereafter, the planar body part 12 is subjected to biaxial drawing blow forming.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method of manufacturing a bottomed cylindrical container in which a preformed body made of a thermoplastic resin called a preform or the like is biaxially stretch blow molded to manufacture a bottomed cylindrical container such as a cup-shaped container. More specifically, the present invention relates to a preform that is suitable for manufacturing a small, thin, light-weight bottomed cylindrical container, and a heating method for the preform that heats the preform and sends it to a blow mold.

  As a cylindrical container with a bottom manufactured by biaxial stretch blow molding, a wide-mouth cup-shaped container made of a thermoplastic resin used as a container for dairy products or the like is known. The wide-mouth cup-shaped container includes a cylindrical body portion with a bottom and a mouth flange that extends outward from the upper end opening of the cylindrical body portion. In addition, a wide-mouth container having a shape in which a slightly small-diameter constricted portion (neck portion) is provided between the mouth flange and the cylindrical body is also known. In general, such a bottomed cylindrical container is sealed by filling a content and then attaching a lid made of aluminum foil or resin synthetic paper to the surface of the mouth flange.

  As a cylindrical container with a bottom, an injection molded product, a vacuum / pressure molded product, and a biaxial stretch blow molded product of a preform (preform, primary molded product) are known. The injection-molded container is manufactured using a resin such as polypropylene or polystyrene, is thick with a thickness of about 0.5 mm, and has poor oxygen barrier performance. A vacuum / pressure formed container is manufactured using a single-layer sheet made of polyethylene terephthalate (PET) or a multilayer sheet of a plurality of types of resins, but has many burrs and a low yield. Further, since the sheet is easily cracked during molding, it is not suitable for molding a container having a deep bottom. A biaxially stretched blow molded container does not generate burrs, has an excellent oxygen barrier performance, and can form a container having a deep bottom.

  For bottomed cylindrical containers such as cup-shaped containers, it is extremely effective to reduce the weight in order to reduce the cost. However, it is difficult to reduce the weight of the biaxially stretched blow molded container. For example, the weight of currently available biaxial stretch blow molded cups is about 11-14 g for a 200 ml cup. Moreover, the shape of the preform used for manufacturing the biaxially stretched blow molded cup is hemispherical, conical or bell-shaped, and is generally an injection-molded product. In the stretch blow molding, it is necessary to heat the preform to a temperature suitable for stretch blow. In the case of a PET preform, the preform is heated to approximately 100 ° C. In order to reduce the weight of the biaxially stretched blow molded cup, it is only necessary to reduce the weight of the preform. In other words, the preform may be thin.

  However, if the preform is too thin, the self-holding property tends to be impaired by heating, and the original shape cannot be maintained when it is heated to a temperature suitable for biaxial stretching blow, and it deforms and collapses. As a result, the biaxial stretch blow molding may be hindered. Therefore, it is necessary to make the wall thickness of the cup-shaped preform used for manufacturing the cup-shaped container greater than 2 mm, and there is a limit to reducing the thickness and weight. Therefore, there is a limit to the reduction in thickness and weight of the cup-shaped container obtained by biaxial stretch blow molding, and a sufficient cost reduction cannot be achieved.

  The inventors of the present invention disclosed in Patent Document 1 a manufacturing method of a bottomed cylindrical container suitable for manufacturing a thin and light bottomed cylindrical container by subjecting a preform to biaxial stretching blow, and A plate-like preform suitable for use in a manufacturing method is proposed.

JP 2010-188711 A

  Here, as containers for dairy products and the like, there is a demand for smaller, thinner and lighter containers. For example, there is a demand for an extremely lightweight bottomed cylindrical container of 5 g or less. For this purpose, it is necessary to biaxially stretch blow-mold the bottomed cylindrical container using a thinner, lighter and smaller plate-shaped preform.

  However, if the plate-shaped preform is made thin, the self-holding property of the preform tends to be impaired by heating. For this reason, when it is heated to a temperature suitable for biaxial stretch blow, the original shape cannot be maintained and it is thermally deformed, which may hinder biaxial stretch blow molding.

  In addition, the center part of the plate-shaped preform, which is the bottom part of the bottomed cylindrical container, is thicker than the outer peripheral part because the stretch ratio is larger than the outer peripheral part. There is a need. In the case of producing a plate-shaped preform by injection molding, generally, the injection molding gate is the central portion in the cavity for molding the plate-shaped preform, that is, the most meat in the plate-shaped preform. The thick part is located at the part to be molded. As a result, at the time of injection molding of the preformed product, the thick portion of the central portion where the gate is located is overheated and crystallized and tends to be whitened. As a result, adverse effects such as deterioration of the molding characteristics of the thick part at the center occur.

  In view of these points, an object of the present invention is to provide a preform having a shape suitable for manufacturing a small, thin and light-weight tubular container with a bottom, and heating the preform and feeding the preform into a blow mold. It is to propose a method for heating a preform suitable for the above. Moreover, the subject of this invention is providing the manufacturing method of a cylindrical container with a bottom which gives a biaxial stretching blow molding to the said preform, and manufactures a cylindrical container with a bottom.

In order to solve the above-mentioned problems, the present invention provides a preformed cylindrical container having a mouth flange by biaxially stretching blow-molding a preform made of thermoplastic resin. Heating a preform to a molding temperature at which biaxial stretch blow molding is possible, and heating the preform after heating to a blow mold,
The preformed body is a plate-like main body portion that is subjected to the biaxial stretching blow molding to become a bottomed container main body portion of the bottomed cylindrical container, and the biaxial stretching blow molding as it is without being subjected to the biaxial stretching blow molding. It has an edge flange that becomes a mouth flange,
A heating element is brought into contact with at least a part of the surface of the plate-shaped main body portion of the preform, and the plate-shaped main body portion is contact-heated to the molding temperature.

  In the method of the present invention, a heating element is brought into contact with a plate-shaped preform and heated. When the thickness of the preform is reduced, thermal deformation such as bending downward may occur in the central portion of the preform that has been softened by heating. Since contact heating is adopted, the preform can be efficiently heated in a short time compared to non-contact heating by radiant heat using an infrared heater or the like, which is a general heating method of the preform. it can. Moreover, thermal deformation can be prevented or suppressed by appropriately bringing the heating element into contact with the preform. Therefore, the plate-shaped preform after heating can be fed into the blow mold without causing any thermal deformation that hinders biaxial stretch blow molding. For this reason, it is possible to use a thinner and lighter preform as a pre-formed product. As a result, the bottomed tubular container obtained by biaxial stretch blow molding can be made thinner and lighter, and the cost can be significantly reduced. Can achieve down.

  Further, since the preform is a plate-shaped preform, it can be manufactured by injection molding as well as by compression molding. Moreover, since the shape is simple, the manufacturing cost of the preform molding die can be reduced, and it can be easily manufactured using various thermoplastic resins such as PP, PE, PEN, PS other than PET. Furthermore, since it is a plate-shaped preform, it is easy to laminate and mold from the same resin or different types of resins, and it is easy to sandwich a coating film or film between each resin layer. It is also easy to sandwich a functional material having heat resistance, oxygen barrier properties, etc. between the layers.

  In the present invention, a heating element having a heating surface complementary to one surface of the plate-like main body is used as the heating element, and the heat generation of the heating element is formed on the surface of the plate-like main body. The plate-shaped main body portion can be contact-heated to the molding temperature while keeping the surfaces in close contact and maintaining this close contact state. In this case, the said surface of the said plate-shaped main-body part can also be heat-sterilized by contact heating.

  By making the heating surface of the heating element a shape complementary to the surface shape of the plate-like main body portion that is the heating target portion of the preform, the heating surface can be brought into close contact with the surface of the plate-like main body portion. Thereby, a plate-shaped main-body part can be heated efficiently. Further, since the plate-like main body is in close contact with the heat generating surface, thermal deformation is reliably prevented or suppressed by the heat generating surface. Furthermore, by heating the surface of the plate-shaped main body portion in a state where the heating surface is in close contact, the surface can also be sterilized by heating. In some cases, it is possible to omit the sterilization step on the surface of the container.

  In this case, the heat generating surface is pressed from the lower side or the upper side with respect to the surface of the plate-like main body portion so as to reliably form a close contact state between the heat generating surface and the surface of the plate-like main body portion, or The plate-like main body is supported by the heat generating surface by vacuum suction, and the plate-like main body is contact-heated to the molding temperature without thermal deformation while maintaining the close contact state. It is desirable.

  In addition, as the heating element, a first heating element provided with a first heating surface having a shape complementary to a first surface on one side of the plate-like main body part which becomes an inner surface of the container main body part, A second heating element provided with a second heating surface having a shape complementary to the second surface on the other side of the plate-like body portion that becomes the outer surface of the container body portion can be used. In this case, by sandwiching the plate-like main body portion between the first and second heat generating surfaces, the first heat generating surface is brought into close contact with the first surface, and the second heat generating surface is brought into contact with the second surface. The plate-like main body portion can be contact-heated to the molding temperature without thermal deformation while maintaining the close contact state. Moreover, the said 1st, 2nd surface of the said plate-shaped main-body part can be heat-sterilized.

  Next, in the preformed body of the present invention, the first surface of the plate-like main body portion of the preformed body has a concave curved surface that becomes the deepest portion at a position on the central axis of the plate-like main body portion, and the concave The second surface of the plate-like main body portion can be defined by a convex curved surface whose top on the central axis is the first flat surface extending outward from the outer peripheral edge of the curved surface.

  When the preform is manufactured by injection molding, the thickness of the maximum thickness of the preform facing the gate of the injection mold can be reduced, and the deterioration of characteristics due to whitening at the center of the preform It is possible to prevent such harmful effects as described above.

In this case, the plate thickness of the plate-like main body portion is gradually increased from the outer peripheral edge portion on the edge flange side toward the center at the portion defined by the first plane and the convex curved surface. The central portion defined by the concave curved surface and the convex curved surface can be maintained at a substantially constant thickness. For example, by defining the concave curved surface and the convex curved surface by an arc surface having a center at the same position, the central portion of the plate-like main body portion can be made to have a constant thickness.

  In addition, as a cylindrical container with a bottom, the thing of the shape which attached | subjected the constriction part smaller diameter than a container main-body part between the mouth part flange and a container main-body part is known. A container having such a shape can be manufactured by subjecting a preform having the following shape to biaxial stretch blow molding.

  In other words, the preform includes a constricted portion that is bent from the inner peripheral edge of the edge flange toward the second surface and is connected to the outer peripheral edge of the plate-like main body.

In the present invention, the preform can be heated while the preform is conveyed along a predetermined path toward the blow mold. For this,
The preform is placed on a frame-shaped transporter having a flange support surface on which the edge flange of the preform is placed,
In this state, transport the transport tool along a predetermined path to the heating element contact position,
In the heating element contact position, the heating element is brought into contact with the plate-like main body portion of the preform formed on the transport tool,
Along with the conveying tool, the heating element brought into contact with the preform is conveyed along a predetermined path to a heating element separation position,
Separating the heating element from the preform at the heating element separation position;
After that, the preform may be sent to the blow mold by the transport tool.

  Next, in the method for manufacturing a bottomed container according to the present invention, the preform after being heated using the above heating method is fed into a blow mold for biaxial stretching blow, and the blow mold is closed. The plate-shaped main body portion of the preform is subjected to biaxial stretching blow in a state where the edge flange of the carrier and the preform is sandwiched.

Further, the present invention is a preform for producing a cylindrical container with a bottom, which is heated using the above heating method and then fed into a blow molding die for biaxial stretch blow,
A plate-like main body portion that is biaxially stretched blow-molded to become a bottomed container body portion of the bottomed tubular container, and a mouth of the bottomed tubular container as it is without being biaxially stretched blow-molded With an edge flange that becomes a part flange,
The plate-like main body includes a first surface on one side that becomes an inner surface of the container main body, and a second surface on the other side that becomes an outer surface of the container main body,
The first surface of the plate-shaped main body is defined by a concave curved surface that is the deepest part at a position on the central axis, and a first plane that extends outward from the outer peripheral edge of the concave curved surface,
The second surface of the plate-like main body is characterized in that the position on the central axis is defined by a convex curved surface having a top.

  Here, in the part prescribed | regulated by the said 1st plane and the said convex curved surface, the plate | board thickness of the said plate-shaped main-body part is made to increase gradually toward the said center from the outer-periphery edge part by the side of the said edge flange. The central portion defined by the concave curved surface and the convex curved surface can be maintained at a constant thickness.

  The preform may be provided with a constricted portion that is bent from the inner peripheral edge of the plate-like edge flange to the second surface side and connected to the outer peripheral edge of the plate-like main body.

(A) is a half cross-sectional side view which shows an example of a cylindrical container with a bottom, (b) is sectional drawing of the preform used for manufacture of a cylindrical container with a bottom. (A), (b), (c) and (d) are planes showing an example of a plate-like preform used for producing the bottomed cylindrical container of FIG. 1 by performing biaxial stretch blow molding. It is a figure, a bottom view, a front view, and a sectional view. (A), (b), (c) and (d) show another example of a plate-shaped preform used for manufacturing the bottomed cylindrical container of FIG. 1 by performing biaxial stretch blow molding. It is a top view, a bottom view, a front view, and a sectional view. (A), (b), (c) and (d) show another example of a plate-shaped preform used for manufacturing the bottomed cylindrical container of FIG. 1 by performing biaxial stretch blow molding. It is a top view, a bottom view, a front view, and a sectional view. (A), (b), (c) and (d) show another example of a plate-shaped preform used for manufacturing the bottomed cylindrical container of FIG. 1 by performing biaxial stretch blow molding. It is a top view, a bottom view, a front view, and a sectional view. FIG. 2 is a conceptual diagram for explaining a heating and conveying method of a preformed body that heats the preformed body of FIG. 2 and sends it to a blow mold and a manufacturing method for manufacturing a bottomed container by subjecting the preformed body to biaxial stretching blow molding. It is. It is explanatory drawing which shows the contact heating of the preforming body in the blow molding apparatus of FIG. It is a top view which shows the structural example of the blow molding apparatus to which this invention is applied. It is explanatory drawing which shows an example of the heating station of the blow molding apparatus of FIG. 6, and the raising / lowering mechanism of a lower side heat generating body.

  Hereinafter, with reference to the drawings, a bottomed cylindrical container according to an embodiment of the present invention (hereinafter simply referred to as “bottomed container”), a plate-shaped preform (hereinafter referred to as “preform”). And a method for manufacturing a bottomed container will be described.

(Bottomed container)
FIG. 1A is a half-sectional side view showing an example of a bottomed cylindrical container, and FIG. 1B is a cross-sectional view of a preform used for manufacturing a bottomed cylindrical container. The bottomed container 1 according to the present embodiment is a thin and light-weight small container having a weight of less than 5 g, for example, a cylindrical container body 2 with a bottom, and an upper end opening edge of the container body 2 And a container opening 3 surrounding the container. The container main body 2 is a stretched portion subjected to biaxial stretch blow, and the container mouth 3 is a non-stretched portion not subjected to biaxial stretch blow.

  The container body 2 has a slightly flat cylindrical shape whose outer diameter is larger than its height. In this example, the container mouth 3 includes a flat mouth flange 4 having a constant width and a constant thickness spreading in a direction orthogonal to the container center axis 1 a, and a container from the inner periphery of the mouth flange 4. A slightly small-diameter mouth constricted portion 5 that is bent in the direction of the central axis 1 a and is connected to the upper end edge portion of the container main body 2 is provided.

  FIG. 2 shows a plate-like preform used for manufacturing the bottomed container 1 by biaxial stretch blow molding, (a) is a plan view, (b) is a bottom view, (c) is a front view, (d ) Is a cross-sectional view. The shape of the preform 10 will be described with reference to FIG.

The preform 10 includes a plate-like main body portion 12 made of a thermoplastic resin such as PET, and an edge portion 13 formed in a state of continuously surrounding the outer peripheral edge portion of the plate-like main body portion 12 and surrounding the outer peripheral edge portion. It has. The plate-like main body portion 12 is a stretched portion that is biaxially stretched and blown to become the container body portion 2 of the bottomed container 1, and the edge portion 13 is left without being subjected to biaxially stretched blow molding. This is a non-stretched portion that remains as the container mouth 3 of the bottomed container 1. Therefore, the edge portion 13 has the same shape as the container mouth portion 3 of the bottomed container 1, and the annular edge flange 14 corresponding to the mouth portion flange 4 and the annular shape corresponding to the mouth constricted portion 5. And an edge constricted portion 15.

  The upper first surface 16 that is one surface of the plate-like main body portion 12 of the preform 10 is a surface portion that becomes the inner surface 6 of the container main body portion 2 of the bottomed container 1, and the second lower surface of the other. The surface 17 is a surface portion that becomes the outer surface 7 of the bottomed container body 2.

  The first surface 16 of the plate-like main body portion 12 is defined by a concave curved surface 16a that is the deepest portion on the central axis 11 and a first flat surface 16b that extends outward from the outer peripheral edge of the concave curved surface 16a. The first plane 16b is a plane extending in a direction perpendicular to the central axis 10a. On the other hand, the second surface 17 on the opposite side of the plate-like main body portion 12 is defined by a convex curved surface 17 a that becomes the top on the central axis 11.

  Thereby, the thickness of the plate-like main body 12 is gradually increased from the edge 13 side toward the central axis 11 at the portion defined by the first flat surface 16b and the convex curved surface 17a. The central portion of the plate-like main body 12 defined by the concave curved surface 16a and the central portion of the convex curved surface 17a is maintained at a substantially constant thickness. This portion is the maximum thickness portion of the preform 10. For example, the maximum thickness portion is set to a thickness of about 6 mm or less.

  When the preform 10 is manufactured by injection molding, generally, a gade is located at a portion corresponding to the center of the plate-like main body portion 12 in a cavity of an injection mold for molding the preform 10. In the case of this example, the gade is located at the top of the center of the second surface 17 defined by the convex curved surface 17a of the preform 10. A recess is formed by a concave curved surface 16a in the central portion of the first surface 16 on the opposite side of the preform 10, and the thickness of the portion where the resin is injected from the gate is reduced. By appropriately setting the amount of depression by the concave curved surface 16a, it is possible to prevent the maximum thick portion of the central portion of the preform 10 from being excessively crystallized and whitened during injection molding.

  3A (a), (b), (c), and (d) are a plan view, a bottom view, a front view, and a sectional view showing another example of a preform. The preform 10A shown in these drawings is defined by planes on both sides of the plate-like main body portion 12A extending in parallel to the direction perpendicular to the central axis 11, and the plate-like main body portion 12A has a constant thickness as a whole. It is a plate part.

  3B (a), (b), (c), and (d) are a plan view, a bottom view, a front view, and a cross-sectional view showing still another example of a preform. In the preform 10B shown in these figures, the edge 13 of the preform 10 is an edge 13B formed only from a flat edge flange.

  3C (a), (b), (c) and (d) are a plan view, a bottom view, a front view and a cross-sectional view showing another example of a preform. In the preform 10C shown in these drawings, the plate-like main body portion 12B of the preform 10B shown in FIG. 3B has a constant thickness except for the outer peripheral edge portion, and the thickness gradually decreases toward the edge portion 13C at the outer peripheral edge portion. It is what you do. Although the illustrated preform has a circular outline, it may have various non-circular outlines such as an elliptical outline and a polygonal outline. Various contour-shaped preforms are used depending on the cylindrical shape of the bottomed container to be manufactured.

(Preform heating method and bottomed container manufacturing method)
FIG. 4 shows a heating method of a preform that is heated while being conveyed while the plate-shaped preform 10 is conveyed and heated to a temperature suitable for biaxial stretch molding, and sent to a blow mold, and suitable for molding by the heating method. It is a conceptual diagram which shows an example of the manufacturing method which performs blow biaxial stretch blow molding to the preform heated at temperature, and manufactures the container 1 with a bottom.

  In the preform heating method, the preform 10 is heated to a temperature suitable for biaxial stretch blow molding by contact heating while being transported along the transport path 21, and sent to the blow molding die 22. The conveyance path 21 is, for example, a circulation path that circulates an annular preform carrier 23 (conveyance tool) at a constant pitch. The preform 10 is supplied from the outside to the preform carrier 23 on the conveyance path 21 at the preform supply position 24. The preform 10 is carried on the preform carrier 23 with the second surface 17 facing upward.

  The preform carrier 23 carrying the preform 10 is conveyed along the conveyance path 21 and is contact-heated to a temperature suitable for biaxial stretch blow molding while passing through a preform heating unit 25 provided in the middle. (See FIG. 5 described later).

  A blow molding die 22 is arranged in a part of the transport path 21 on the downstream side in the transport direction of the preform heating unit 25. In the blow mold 22, a preform carrier 23 carrying the heated preform 10 is sent to the blow mold 22 in a mold open state. When the preform carrier 23 is fed, the blow mold 22 is closed and biaxial stretch blow molding is performed on the preform 10 to obtain the container 1 with the bottom.

  After the bottomed container 1 is sent out from the blow mold 22, it is removed from the preform carrier 23 at a container collection position 26 on the conveyance path 21 and collected at a predetermined place. The preform carrier 23 which has become empty returns to the preform supply position 24 along the preform conveyance path 21 again.

  FIGS. 5A and 5B are explanatory diagrams showing the contact heating operation of the preform by the heating element for heating the preform arranged in the preform heating unit 25. FIG.

  First, as shown in FIG. 5A, the preform carrier 23 has an annular shape, and the inner peripheral edge portion of the annular upper surface 23a becomes an annular flange support surface 23b that is lowered by one step. ing. The preform 10 is carried on the preform carrier 23 in a state where the edge flange 14 of the edge 13 is placed on the flange support surface 23 b at the preform supply position 24, and is conveyed along the conveyance path 21.

  In this state, the preform carrier 23 is conveyed to the heating element contact position 25a (see FIG. 4) in the preform heating unit 25. An upper heating element 31 and a lower heating element 32 are disposed in the preform heating unit 25. As shown in FIG. 5A, the upper heating element 31 and the lower heating element 32 stand by above and below the conveyance path 21.

  For example, the upper heating element 31 and the lower heating element 32 are lowered and raised while moving along the conveyance path 21 in synchronization with the preform carrier 23 from the time before the heating element contact position 25a. As a result, as shown in FIG. 5B, at the heating element contact position 25a, the preform 10 held on the preform carrier 23 is gripped by the upper heating element 31 and the lower heating element 32 from above and below. Form.

The preform 10 is transported along the transport path 21 while the upper heating element 31 and the lower heating element 32 are in close contact with each other from above and below. Thereby, the preform 10 is contact-heated to a temperature suitable for biaxial stretch blow molding. When the preform carrier 23 reaches the heating element separation position 25b (see FIG. 4), the upper heating element 31 and the lower heating element 32 are retracted in the vertical direction. The upper heating element 31 and the lower heating element 32 after being retracted up and down are returned again to the heating element contact position 25a side of the transport path 21. By circulating a plurality of sets of the upper heating element 31 and the lower heating element 32 in synchronization with the preform carrier 23 between the heating element contact position 25a and the heating element separation position 25b,
The contact heating operation of the preform 10 can be performed continuously or batchwise.

  Here, the upper heating element 31 of the preform heating unit 25 includes an upper heating surface 31 a having a concave curved surface shape complementary to the second surface 17 of the preform 10. Similarly, the lower heating element 32 includes a lower heating surface 32 a having a surface shape complementary to the first surface 16 of the preform 10. Specifically, the lower heat generating surface 32 a includes a convex curved surface portion 32 b corresponding to the concave curved surface 16 a of the first surface 16 and a flat surface portion 32 c corresponding to the first flat surface 16 b of the first surface 16.

  Therefore, in the contact heating using the upper heating element 31 and the lower heating element 32, the upper heating surface 31 a and the lower heating surface 32 a are in close contact with the surfaces on both sides of the preform 10. Therefore, contact heating can be performed efficiently and the preform 10 can be heated to a temperature suitable for biaxial stretch blow molding in a short time. That is, the preform 10 can be heated so as to obtain an optimum temperature state for the biaxial stretch blow molding when it is fed into the blow mold 22 and biaxial stretch blow molding is performed. For example, the preform 10 is heated to 70 to 120 ° C.

  During contact heating, the plate-like main body portion 12 of the preform 10 is gripped from both sides by the upper heat generating surface 31a and the lower heat generating surface 32a, so that the thin plate-like main body portion 12 is not thermally deformed. Can be heated.

  Further, since contact heating is performed in a close state, both side surfaces of the preform 10 are simultaneously heat sterilized. For example, the surface of the preform 10 can be reliably sterilized by heating by heating the preform 10 to a predetermined temperature and maintaining the heating state for a certain period of time.

  In this example, the preform 10 is heated by contact using the upper heating element 31 and the lower heating element 32. For example, it is possible to heat the preform 10 from the upper side (from the second surface 17 side) using only the upper heating element 31.

  Further, for example, as indicated by an imaginary line in FIG. 5A, a large number of air holes 31d are formed in the upper heating surface 31a, and the preform 10 can be heated while being vacuum-sucked in a contact heating state. . Thereby, the thermal deformation of the thin preform 10 can be prevented. After the heating is finished, the air hole 31d can be switched to a pressurized state so that the preform 10 is separated from the upper heat generating surface 31a.

  Conversely, it is also possible to heat the preform 10 from below using only the lower heating element 32. Also in this case, air holes 32d are formed in the lower heat generating surface 32a as indicated by imaginary lines in FIG. 5A, and the preform 10 during contact heating is securely in contact with the lower heat generating surface 32a. It may be supported by.

  Such air holes 31d and 32d can be provided on both the upper heat generating surface 31a and the lower heat generating surface 32a shown in FIG.

(Specific configuration of blow molding equipment)
FIG. 6 is a plan view showing a specific configuration example of a blow molding apparatus for manufacturing the bottomed container 1 by performing biaxial stretch blow molding on the preform 10 having the above configuration. The blow molding apparatus 40 includes a supply station 41 to which the preform 10 is supplied from the outside. At the supply station 41, an annular carrier 42 for holding and transporting the preform 10 is waiting. The carrier 42 has the same configuration as the preform carrier 23 shown in FIG.
For example, four carriers 42 are waiting at the supply station 41 simultaneously. Each carrier 42 carries the preform 10 as shown in FIG.

  The carrier 42 carrying the preform 10 is transferred along a supply path 43 that is a linear conveyance path and delivered to the heating station 44. In the heating station 44, for example, a carrier transport groove 45 a made of a semicircular recess is formed at a constant pitch in the circumferential direction on a circular outer peripheral edge of a disk-shaped horizontal rotating plate 45. The carrier 42 mounted in each carrier transport groove 45 a is transported along a circular transport path 46 as the horizontal rotating plate 45 rotates.

  In the conveyance path 46, a part intersecting with the downstream end of the linear supply path 43 extending from the supply station 41 is a preform charging position 47. On the side of the preform loading position 47, a loading star wheel 48 is arranged. With the rotation of the charging star wheel 48, the transfer recess 48a formed on the outer peripheral surface thereof receives the carrier 42 from the supply path 43, and conveys the carrier positioned at the preform loading position 47 of the circular conveyance path 46. The carrier 42 is handed over to the groove 45a.

  The carrier 42 introduced into the circular conveyance path 46 from the preform introduction position 47 reaches the preform delivery position 51 through the heating element contact position 49 and the heating element separation position 50 in the middle of the conveyance path. While the preform 10 carried on the carrier 42 is transported from the heating element contact position 49 to the heating element separation position 50, the upper heating element 31 and the upper heating surface 31a of the lower heating element 32 from the upper and lower sides, the lower side It is held between the heat generating surfaces 32a and is in close contact with them. In this state, the preform 10 is heated by contact from both sides (see FIG. 5).

  A feeding star wheel 52 is arranged on the side of the preform delivery position 51 of the circular conveyance path 46. The carrier 42 carrying the preform 10 is sent out from the preform delivery position 51 to the pitch conversion mechanism 54 by the delivery star wheel 52 via the delivery path 53 that is a linear conveyance path. The pitch conversion mechanism 54 includes four pitch conversion arms 55 that receive the carrier 42 delivered from the delivery path 53 in the delivery pitch. When the carrier 42 is received by each of the four pitch conversion arms 55, these four pitch conversion arms 55 move along the linear conveyance path 56 while expanding the pitch, and are biaxially stretch blow molded. It spreads to the pitch suitable for. In this state, four carriers 42 are delivered to the blow molding station 57 by four.

  The blow molding station 57 is a station for taking four pieces, and the blow molding die 58 includes four molding cavities 58 a formed at a constant pitch along a linear conveyance path 59. The preforms 10 carried on the respective carriers 42 positioned in the respective cavities 58a are biaxially stretched and blow-molded after clamping to form the bottomed container 1. After the biaxial stretch blow molding is completed and the mold opening is performed, the four carriers 42 carrying the bottomed container 1 are discharged from the blow molding station 57 along the straight conveyance path 59, It is sent to the product discharge station 60.

  The product discharge station 60 is provided with a product collection mechanism 62 that pulls the bottomed container 1 upward from the carrier 42 and inverts it and discharges it to the linear product discharge path 61 in an upright posture. The product recovery mechanism 62 includes four arms 62a, and grips the container mouth portion 3 of each bottomed container 1 with the opening / closing chuck 62b of the arm. And it rotates to the up-down direction around the horizontal rotating shaft 62c, and the container 1 with a bottom is discharged | emitted to the product discharge path 61 located in the other side. The bottomed container 1 is discharged to the discharge side along the product discharge path 61 and is collected at a predetermined place.

The empty carriers 42 after the bottomed containers 1 are collected are four horizontal turntables 6 each.
3 is rotated 180 degrees and supplied to the linear carrier supply path 64. The carrier 42 supplied to the carrier supply path 64 is sent out along the carrier supply path 64 by the carrier delivery mechanism 65 and supplied to the preform supply station 41. The empty carrier 42 supplied to the preform supply station 41 waits there and waits for the supply of the preform 10.

  FIG. 7A is a schematic plan view showing the heating station 44 taken out, and FIG. 7B is a conceptual diagram showing an elevating mechanism of the lower heating element 32.

  In the heating station 44, a carrier transport groove 45 a that transports the carrier 42 along the circular transport path 46 is formed on the outer peripheral edge of the horizontal rotating plate 45 at regular intervals in the circumferential direction. An upper heating element 31 and a lower heating element 32 (not shown) are arranged above and below each carrier transport groove 45a, respectively. These heating elements 31 and 32 are united with the horizontal rotating plate 45 by the heating element rotating mechanism 70 and rotate around the vertical center line 45b. Accordingly, each heating element 31, 32 moves along the circular conveyance path 46 together with each carrier 42.

  The heating element raising / lowering mechanism 80 for raising and lowering the lower heating element 32 in the direction of the central axis 45b raises the lower heating element 32 from the standby position before the heating element contact position 49 in the circular transport path 46. At the heating element contact position 49, the heating surface 32 a is brought into close contact with the plate-like main body portion 12 of the preform 10 carried on the carrier 42. The state where the lower heating element 32 is in the raised position, that is, the contact heating state is maintained up to the transport position before the heating element separation position 50. Then, as the carrier 42 is transported, the lower heating element 32 is lowered, and at the heating element removal position 50, the lower heating element 32 is retracted downward from the preform 10 and returned to the standby position again.

  As shown in FIG. 7B, the heating element elevating mechanism 80 can be constituted by a cam mechanism 90 and a heating element rotating mechanism 70, for example. The cam mechanism 90 includes a cam member 92 having a cam surface 91 formed along the conveyance path 46, and a cam follower 93 such as a roller attached to each lower heating element 32 so as to slide along the cam surface 91. It has.

  In this case, it is desirable to include a rotation mechanism 94 that rotates the cam member 92 about the vertical rotation shaft 45 b of the horizontal rotation plate 45. When the cam member 92 is rotated by a predetermined angle, the heating element contact position 49 and the heating element separation position 50 on the conveyance path 46 defined by the cam surface 91 of the cam member 92 are set on the upstream side or the downstream side of the conveyance path 46. Can be moved to a position.

  In addition, although the raising / lowering mechanism 80 of the lower side heat generating body 32 was shown in FIG.7 (b), the raising / lowering mechanism of the upper side heat generating body 31 can also be comprised similarly.

DESCRIPTION OF SYMBOLS 1 Container with a bottom 1a Container center axis 2 Container main-body part 3 Container mouth part 4 Mouth flange 5 Mouth part 6 Inner surface 7 Outer surface 10 Preform 11 Center axis 12 Plate-shaped main body part 13 Edge part 14 Edge flange 15 Edge constricted portion 16 First surface 16a Concave surface 16b First plane 17 Second surface 17a Convex surface 21 Preform conveyance path 22 Blow mold 23 Preform carrier 23a Upper surface 23b Flange support surface 24 Preform supply position 25 Preform heating Portion 25a Heating element contact position 25b Heating element detachment position 31 Upper heating element 31a Upper heating surface 31d Air hole 32 Lower heating element 32a Lower heating surface 32b Convex curve portion 32c Plane portion 32d Air hole

Claims (14)

Molding that allows the biaxially stretched blow molding of the preformed body to produce a bottomed cylindrical container having a mouth flange by performing biaxially stretched blow molding on a thermoplastic resin preformed body. A method of heating a preform that is heated to a temperature,
The preformed body is a plate-like main body portion that is subjected to the biaxial stretching blow molding to become a bottomed container main body portion of the bottomed cylindrical container, and the biaxial stretching blow molding as it is without being subjected to the biaxial stretching blow molding. It has an edge flange that becomes a mouth flange,
A heating method for a preform, wherein a heating element is brought into contact with at least a part of the surface of the plate-like main body portion of the preform, and the plate-like main body portion is contact-heated to the molding temperature. As the heating element, a heating element having a heating surface complementary to the one surface of the plate-like main body is used,
Bringing the heating surface of the heating element into close contact with the surface of the plate-shaped main body,
The method for heating a preform according to claim 1, wherein the plate-like main body is contact-heated to the molding temperature while maintaining the close state.   The method for heating a preform according to claim 2, wherein the surface of the plate-like main body is sterilized by heating by performing the contact heating. The heating surface is brought into close contact with the surface of the plate-like main body portion from below or above by pressing or vacuum suction, and the plate-like main body portion is supported by the heating surface,
The method for heating a preform according to claim 2, wherein the plate-shaped main body is contact-heated to the molding temperature without thermal deformation while maintaining the close contact state. As the heating element, a first heating element provided with a first heating surface having a shape complementary to a first surface on one side of the plate-like body part which becomes an inner surface of the container body part, and the container body A second heating element having a second heating surface complementary to the second surface on the other side of the plate-like main body that becomes the outer surface of the part,
By sandwiching the plate-like main body portion between the first and second heat generation surfaces, the first heat generation surface is brought into close contact with the first surface, and the second heat generation surface is brought into close contact with the second surface,
The method for heating a preform according to claim 1, wherein the plate-shaped main body is contact-heated to the molding temperature without thermal deformation while maintaining the close contact state.   The method for heating a preform according to claim 5, wherein the first and second surfaces of the plate-like main body are heat sterilized by performing the contact heating. One surface of the plate-like main body portion in the preform is a first surface that becomes an inner surface of the container main body portion, and the other surface is a second surface that becomes an outer surface of the container main body portion. Yes,
The first surface of the plate-shaped main body is defined by a concave curved surface that is the deepest part at a position on the central axis of the preform and a first plane that extends outward from the outer peripheral edge of the concave curved surface,
The heating of the preform according to any one of claims 1 to 6, wherein the second surface of the plate-like main body is defined by a convex curved surface that becomes a top at a position on the central axis. Method. The plate thickness of the plate-shaped main body is:
The portion defined by the first plane and the convex curved surface gradually increases from the outer peripheral edge portion on the edge flange side toward the central axis.
The method for heating a preform according to claim 7, wherein a central portion defined by the concave curved surface and the convex curved surface is maintained at a constant maximum thickness. The preform includes a constricted portion that is bent from the inner peripheral edge of the edge flange to the second surface side and is connected to the outer peripheral edge of the plate-like main body part;
The preformed body according to claim 7 or 8, wherein the constricted portion is a portion that becomes a container constricted portion connected to the mouth flange of the bottomed cylindrical container as it is without being subjected to the biaxial stretch blow molding. Heating method. The preform is placed on a frame-shaped transporter having a flange support surface on which the edge flange of the preform is placed,
In this state, transport the transport tool along a predetermined path to the heating element contact position,
In the heating element contact position, the heating element is brought into contact with the plate-like main body portion of the preform formed on the transport tool,
Along with the conveying tool, the heating element brought into contact with the preform is conveyed along a predetermined path to a heating element separation position,
Separating the heating element from the preform at the heating element separation position;
The method for heating a preform according to any one of claims 1 to 9. Using the method for heating a preform according to claim 10, the preform is fed into a blow molding die for biaxial stretching blow,
The bottom is characterized in that a biaxially stretched blow is applied to the plate-like main body portion of the preform in a state where the blow mold is closed and the edge flange of the carrier and the preform is sandwiched. Manufacturing method of a cylindrical container with attachment. A bottomed tube provided with a mouth flange, which is supplied to a blow molding die for biaxial stretch blow using a heating method according to claim 1 while being heated to a temperature capable of biaxial stretch blow molding. A preform used for manufacturing a container,
A plate-like main body portion that is subjected to biaxial stretching blow molding to become a bottomed container main body portion of the bottomed cylindrical container, and the bottomed tubular container as it is without being subjected to biaxial stretching blow molding. With an edge flange that becomes a mouth flange,
One surface of the plate-like main body portion is a first surface that becomes an inner surface of the container main body portion, and the other surface is a second surface that becomes an outer surface of the container main body portion,
The first surface of the plate-like main body is defined by a concave curved surface that is the deepest at a position on the central axis of the plate-like main body and a first plane that extends outward from the outer peripheral edge of the concave curved surface. ,
The said 2nd surface of the said plate-shaped main-body part is the preforming body for cylindrical containers with a bottom currently prescribed | regulated by the convex curved surface used as the top in the position on the said central axis. The plate thickness of the plate-shaped main body is:
The portion defined by the first plane and the convex curved surface gradually increases from the outer peripheral edge portion on the edge flange side toward the central axis.
The preform for manufacturing a bottomed cylindrical container according to claim 12, wherein a central portion defined by the concave curved surface and the convex curved surface is maintained at a constant maximum thickness. Comprising a constricted portion bent from the inner peripheral edge of the edge flange to the second surface side and connected to the outer peripheral edge of the plate-like main body part;
14. The bottomed tubular shape according to claim 12 or 13, wherein the constricted portion is a portion that becomes a container constricted portion connected to the mouth flange of the bottomed tubular container as it is without being subjected to the biaxial stretch blow molding. A preform for container production.