JP6533422B2 - Method of heating preform, method of manufacturing bottomed cylindrical container and preform - Google Patents

Description

  The present invention relates to a method for producing a bottomed cylindrical container for producing a bottomed cylindrical container such as a cup-shaped container by biaxially stretch blow molding a preform made of a thermoplastic resin called a preform or the like. More particularly, the present invention relates to a preform suitable for the production of a small-sized thin-walled lightweight lightweight bottomed cylindrical container, and a method for heating the preform and feeding the preform into a blow mold.

  As a bottomed cylindrical container manufactured by biaxial stretch blow molding, a wide-mouthed cup-shaped container made of a thermoplastic resin used as a container for dairy products and the like is known. The wide-mouthed cup-like container comprises a bottomed cylindrical body and a mouth flange extending continuously outward from the upper end opening of the cylindrical body. Also known is a wide-mouthed container with a slightly smaller diameter neck portion between the mouth flange and the cylindrical body. Such a bottomed cylindrical container is generally sealed by bonding a lid made of aluminum foil, resin synthetic paper or the like to the surface of the mouth flange after filling the contents.

  As bottomed cylindrical containers, biaxially stretched blow-molded articles of injection-molded articles, vacuum pressure-molded articles, and preforms (preforms, primary molded articles) are known. The injection-molded container is manufactured using a resin such as polypropylene and polystyrene, has a wall thickness of about 0.5 mm, is heavy, and has poor oxygen barrier performance. The 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 there are many burrs and the yield is low. In addition, since the sheet is likely to be cracked at the time of molding, it is not suitable for forming a deep bottom container. The biaxially oriented blow molded container is free of burrs, has good oxygen barrier performance, and can be used to form deep bottom containers.

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

  However, if the preform is too thin, the self-holding property is likely to be impaired by heating, and at the time of heating to a temperature suitable for biaxial stretch blow, the original shape can not be maintained and the shape is deformed and crushed. It may cause problems in biaxial stretch blow molding. Therefore, it is necessary to make the thickness of the cup-shaped preform used for manufacturing the cup-shaped container more than 2 mm, and there is a limit to the reduction in thickness and weight. Therefore, there is a limit to the thinness and weight reduction of the cup-shaped container obtained by biaxial stretch blow molding, and sufficient cost reduction can not be achieved.

  The present inventors, in Patent Document 1, a method for producing a bottomed cylindrical container suitable for producing a thin and light bottomed cylindrical container by subjecting a preform to biaxial stretching and blowing, 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 need for very light weight bottomed tubular containers of 5 g or less. For this purpose, it is necessary to biaxially stretch blow-mold the bottomed tubular container using a thinner, lighter, and smaller plate-shaped preform.

  However, when the plate-shaped preform is made thin, the self-holding property of the preform tends to be impaired by heating. For this reason, when heated to a temperature suitable for biaxial stretch blow, the original shape can not be maintained, and thermal deformation may occur, which may cause problems in biaxial stretch blow molding.

  In addition, the central portion of the plate-like preform, which is the portion on the bottom side of the bottomed tubular container, is thicker than the portion on the outer peripheral side because the draw ratio is larger than that on the outer peripheral side. There is a need. When producing a plate-like preform by injection molding, in general, the gate for injection molding is the central portion of the plate-like preform molding cavity, ie, the most thick plate-like preform. The thick part is located at the forming site. As a result, at the time of injection molding of the preform, the central thick portion where the gate is positioned is likely to be heated and crystallized to be whitened. As a result, adverse effects such as deterioration of molding characteristics of the central thick portion occur.

  The object of the present invention is, in view of these points, a preformed body having a shape suitable for producing a small-sized, thin-walled, lightweight, bottomed cylindrical container, and heating the preformed body to feed it into a blow molding die The present invention is to propose a method of heating a preform suitable for the purpose. Moreover, the subject of this invention is providing the manufacturing method of the bottomed cylindrical container which performs biaxial stretching blow molding to the said preforming body, and manufactures a bottomed cylindrical container.

In order to solve the above-mentioned problems, the present invention performs the biaxial stretch blow molding on a thermoplastic resin preform to produce a bottomed cylindrical container having a mouth flange, the above-mentioned preform A method of heating a preform, wherein the article is heated to a molding temperature at which the biaxial stretch blow molding can be performed, and the heated preformed product is fed to a blow molding die,
The preformed body is subjected to the biaxial stretch blow molding to be a plate-like main body portion which becomes a bottomed container main body portion of the bottomed cylindrical container, and the biaxial stretch blow molding is not applied. And an edge flange which becomes an opening flange,
The heat generating element is brought into contact with at least a part of the surface of the plate-like main body of the preform, and the plate-like main body is brought into contact heating to the forming temperature.

  In the method of the present invention, a plate-shaped preform is brought into contact with a heating element for heating. When the thickness of the preform is reduced, thermal deformation such as bending downward may occur in the central portion of the preform softened by heating. Since contact heating is employed, the preform can be efficiently heated in a short time as compared to the case of non-contact heating by radiant heat using an infrared heater or the like which is a general heating method of the preform. it can. Further, the thermal deformation can be prevented or suppressed by bringing the heating element into contact with the preformed body appropriately. Therefore, the plate-like preform after heating can be fed into the blow molding die without accompanying thermal deformation which may cause problems in biaxial stretch blow molding. For this reason, it is possible to use thinner and lighter preformed products as compared with the prior art, and as a result, thin-walled / weight-reduced bottomed cylindrical container obtained by biaxial stretch blow molding, and significant cost You can achieve down.

  Further, since the preform is a plate-shaped preform, it can be manufactured by compression molding as well as by injection molding. In addition, 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, etc. other than PET. Furthermore, since it is a plate-like preform, it is easy to laminate-mold it from the same resin or different resins, and it is also easy to sandwich a coating film or a film between each resin layer, and furthermore, each resin It is also easy to sandwich a functional material with heat resistance, oxygen barrier properties, etc. between the layers.

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

  The heat generating surface can be brought into close contact with the surface of the plate-like main body by making the heat-generating surface of the heat generating body complementary to the surface shape of the plate-like main body which is the heating target of the preform. Thus, the plate-like main body can be efficiently heated. Further, since the plate-like main body portion is in close contact with the heat generating surface, the heat generating surface reliably prevents or suppresses the thermal deformation. Furthermore, the surface can be heat-sterilized by heating in a state where the heat generating surface is in close contact with the surface of the plate-like main body, and a sterilization process of the surface of the plate-like main body performed as a post process or In some cases it may be possible to dispense with the process of sterilizing the surface of the container.

  In this case, the heat generation surface is pressed from the lower side or the upper side with respect to the surface of the plate-like main body so that the close contact state between the heat generation surface and the surface of the plate-like main body can be formed reliably. The vacuum heating is brought into close contact to support the plate-like main body by the heat generating surface, and the plate-like main body is contact-heated to the forming temperature without thermal deformation while maintaining the close contact state. Is desirable.

  Further, as the heating element, a first heating element provided with a first heating surface having a shape complementary to the first surface on one side of the plate-like main body, which is the inner surface of the container main body; It is possible to use 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 main body, which is the outer surface of the container main body. In this case, the first heat generating surface is brought into close contact with the first surface by sandwiching the plate-like main body between the first and second heat generating surfaces, and the second heat generating surface is formed as the second surface. The plate-like main body can be contact-heated to the forming temperature without thermal deformation while maintaining the close-contact state. Further, the first and second surfaces of the plate-like main body can be heat-sterilized.

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

  In the case where the preform is produced by injection molding, the thickness of the portion of the preform having the largest thickness facing the gate of the injection mold can be reduced, and the characteristic deterioration due to whitening in the center portion of the preform And the like can be prevented.

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

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

  That is, the preform has a constricted portion which is bent from the inner peripheral edge of the edge flange toward the second surface and connected to the outer peripheral edge of the plate-like main body.

In the present invention, heating of the preform can be performed while conveying the preform along a predetermined path toward the blow mold. For this purpose
Placing the preform on a frame-like carrier provided with a flange support surface on which the edge flange of the preform is placed;
In this state, the transport tool is transported along the predetermined path to the heating element contact position,
Bringing the heating element into contact with the plate-like main portion of the preform on the transfer tool at the heating element contact position;
Conveying the heating element brought into contact with the preform together with the transfer tool along a predetermined path to a heating element removal position;
Releasing the heating element from the preform at the heating element release position;
After that, the preform may be fed into the blow mold by the carrier.

  Next, in the method for producing 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 stretch blow, and the blow mold is closed. It is characterized in that the plate-like main portion of the preform is subjected to biaxial stretch blow in a state in which the carrier tool and the edge flange of the preform are held.

The present invention is also a preform for producing a bottomed cylindrical container which is fed to a blow molding die for biaxial stretching blow after being heated using the above-mentioned heating method,
A plate-like main body portion which is subjected to biaxial stretch blow molding and becomes a bottomed container main body portion of the bottomed tubular container, and an opening of the bottomed tubular container as it is without the biaxial stretch blow molding being applied. With an edge flange that becomes the
The plate-like main body includes a first surface on one side to be an inner surface of the container main body and a second surface on the other side to be an outer surface of the container main body.
The first surface of the plate-like main body portion is defined by a concave surface which is a deepest portion at a position on the central axis, and a first plane which extends outward from an outer peripheral edge of the concave surface,
The second surface of the plate-like main body portion is characterized in that a position on the central axis is defined by a convex curved surface which is a top.

  Here, in the portion defined by the first flat surface and the convex curved surface, the thickness of the plate-like main body is gradually increased from the outer peripheral edge on the side of the edge flange toward the center In the central portion defined by the concave surface and the convex surface, a constant thickness can be maintained.

  Further, the preforming body may include a constricted portion which is bent from the inner peripheral edge of the flat plate-like edge flange toward the second surface and connected to the outer peripheral edge of the plate-like main body.

(A) is a half cross-section side view which shows an example of a bottomed cylindrical container, (b) is sectional drawing of the preforming body used for manufacture of a bottomed cylindrical container. (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 biaxial stretch blow molding They are a figure, a bottom view, a front view, and a sectional view. (A), (b), (c) and (d) show another example of plate-like preforms used for biaxial stretch blow molding to produce the bottomed tubular container of FIG. They are a top view, a bottom view, a front view, and a sectional view showing. (A), (b), (c) and (d) show another example of plate-like preforms used for biaxial stretch blow molding to produce the bottomed tubular container of FIG. They are a top view, a bottom view, a front view, and a sectional view showing. (A), (b), (c) and (d) show another example of plate-like preforms used for biaxial stretch blow molding to produce the bottomed tubular container of FIG. They are a top view, a bottom view, a front view, and a sectional view showing. The schematic diagram for demonstrating the manufacturing method of heating-conveying the preformed body which heats the preformed body of FIG. 2 and sends it to a blow molding die, and a manufacturing method which performs biaxial stretching blow molding on a preformed body, and manufactures a bottomed container. 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 showing the example of composition of the blow molding device to which the present 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 heating element.

  Hereinafter, with reference to the drawings, a bottomed cylindrical container (hereinafter simply referred to as a “bottomed container”) according to an embodiment of the present invention, a plate-shaped preformed body (hereinafter, “preform”, And how to make the bottomed container.

(Bottomed container)
Fig.1 (a) is a half section side view which shows an example of a bottomed cylindrical container, FIG.1 (b) is sectional drawing of the preforming body used for manufacture of a bottomed cylindrical container. The bottomed container 1 according to the present embodiment is, for example, a thin-walled lightweight small-sized container having a weight of less than 5 g, and has a container body 2 with a cylindrical bottom and the upper opening edge of the container body 2 And a container mouth 3 surrounding the The container body 2 is a stretched portion subjected to biaxial stretch blow, and the container opening 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 the present embodiment, the container opening 3 is a flat-shaped opening flange 4 having a constant width and a constant thickness extending in a direction orthogonal to the container central axis 1 a and the container from the inner peripheral edge of the opening flange 4 A slightly smaller diameter neck portion 5 which is bent in the direction of the central axis 1 a and connected to the upper end edge portion of the container body 2 is provided.

  Fig. 2 shows a plate-like preform used to manufacture 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 FIGS. 1 (b) and 2.

The preform 10 has a plate-like main body 12 made of a thermoplastic resin such as PET, and an edge 13 formed continuously around the outer peripheral edge of the plate-like main body 12 so as to surround the outer peripheral edge. Is equipped. The plate-like main body portion 12 is a stretched portion which is subjected to biaxial stretch blow molding and becomes the container body portion 2 of the bottomed container 1, and the edge portion 13 is not subjected to biaxial stretch blow molding, This is a non-stretched portion remaining as the container mouth 3 of the bottomed container 1. Accordingly, the edge 13 has the same shape as the container opening 3 of the bottomed container 1 and has an annular shape corresponding to the annular edge flange 14 corresponding to the opening flange 4 and the opening constriction 5. And an edge constricted portion 15.

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

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

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

  When the preform 10 is manufactured by injection molding, generally, in the cavity of the injection mold for molding the preform 10, the gate is located at a portion corresponding to the center of the plate-like main body portion 12. In the case of this example, the gate is located at the top of the center of the second surface 17 defined by the convex curved surface 17 a of the preform 10. A concave portion 16a is formed on the central portion 16 of the first surface on the opposite side of the preform 10 to reduce the thickness of the portion into which the resin is injected from the gate. By appropriately setting the amount of depression due to the concave curved surface 16a, it is possible to prevent excessive crystallization and whitening of the largest thick portion of the central portion of the preform 10 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 the preform. In the preform 10A shown in these figures, the plane on both sides of the plate-like main body 12A is defined by a plane extending parallel to the direction orthogonal to the central axis 11, and the plate-like main body 12A has a constant thickness as a whole. It is a board part.

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

  FIGS. 3C (a), (b), (c) and (d) are a plan view, a bottom view, a front view and a sectional view showing another example of the preform. In the preform 10C shown in these figures, the plate-like main portion 12B of the preform 10B shown in FIG. 3B has a constant thickness excluding the outer peripheral edge portion, and the thickness gradually decreases toward the edge portion 13C at the outer peripheral edge portion It is intended to Although the illustrated preform has a circular contour, it may have various non-circular contours such as an elliptical contour and a polygonal contour. Depending on the cylindrical shape of the bottomed container to be manufactured, preforms of various contour shapes are used.

(Method of heating preform and method of manufacturing bottomed container)
FIG. 4 is a heating method of the preform which is heated while conveying the plate-like preform 10 and heated to a temperature suitable for biaxial stretch molding and sent to the blow molding die, and it is suitable for molding by the heating method It is a conceptual diagram which shows an example of the manufacturing method which performs blow biaxial stretching 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 transported along the transport path 21 to a temperature suitable for biaxial stretch blow molding by contact heating and fed to the blow mold 22. The transport path 21 is, for example, a circulation path that circulates the annular preform carrier 23 (transport tool) at a constant pitch. The preform carrier 23 on the transport path 21 is externally supplied with the preform 10 at the preform supply position 24. The preform 10 is carried by the preform carrier 23 with its second surface 17 facing up.

  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 the preform heating unit 25 provided in the middle thereof. (See FIG. 5 described later).

  A blow molding die 22 is disposed at the downstream side of the conveyance direction of the preform heating unit 25 in the conveyance path 21. In the blow mold 22, the preform carrier 23 carrying the heated preform 10 is fed into the blow mold 22 in the mold open state. When the preform carrier 23 is fed, the blow mold 22 is closed, and the preform 10 is subjected to biaxial stretch blow molding to obtain the bottomed container 1.

  The bottomed container 1 is delivered from the blow mold 22 and then removed from the preform carrier 23 at a container recovery position 26 on the transport path 21 and recovered at a predetermined location. The preform carrier 23 which has become empty returns to the preform supply position 24 again along the preform conveyance path 21.

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

  First, as shown in FIG. 5 (a), the preform carrier 23 has an annular shape, and the portion on the inner peripheral edge side of the annular upper surface 23a becomes an annular flange supporting surface 23b that is lowered by one step. ing. The preform 10 is carried by the preform carrier 23 with the edge flange 14 of the edge 13 thereof resting on the flange support surface 23b at the preform feeding position 24, and is conveyed along the conveyance path 21.

  In this state, the preform carrier 23 is transported 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 at the upper and lower sides of 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 transport path 21 in synchronization with the preform carrier 23 from a point before the heating element contact position 25a. As a result, as shown in FIG. 5B, in the heating element contact position 25a, the preform 10 carried 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 detachment position 25b (see FIG. 4), the upper heating element 31 and the lower heating element 32 retract in the vertical direction. The upper heating element 31 and the lower heating element 32 that have been retracted up and down are returned again to the heating element contact position 25 a of the transport path 21. By circulating the plurality of sets of upper heating element 31 and lower heating element 32 in synchronization with preform carrier 23 between heating element contact position 25a and heating element detachment 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 is provided with an upper heating surface 31 a having a concave surface shape complementary to the second surface 17 of the preform 10. Similarly, the lower heating element 32 is provided with 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 contact heating using the upper heating element 31 and the lower heating element 32, the upper heating surface 31a and the lower heating surface 32a are in close contact with the surfaces on both sides of the preform 10. Therefore, contact heating can be efficiently performed, and the preform 10 can be heated to a temperature suitable for biaxial stretch blow molding in a short time. That is, at the time of being fed into the blow mold 22 and subjected to biaxial stretch blow molding, the preform 10 can be heated so as to obtain a temperature state optimum for the biaxial stretch blow molding. For example, the preform 10 is heated to 70 to 120 ° C.

  During the contact heating, since the plate-like main body 12 of the preform 10 is gripped from both sides by the upper heating surface 31a and the lower heating surface 32a, the thin plate-like main body 12 is not accompanied by thermal deformation. It can be heated.

  Moreover, since contact heating is performed in a close state, heat sterilization is simultaneously applied to both sides of the preform 10. For example, the surface of the preform 10 can be reliably heat-sterilized by heating the preform 10 to a predetermined temperature and maintaining the heated state for a certain period of time.

  In the present embodiment, the preform 10 is contact-heated using the upper heating element 31 and the lower heating element 32. For example, it is also 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 shown 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 vacuum suctioning in a contact heating state. . Thereby, the thermal deformation of the thin preform 10 can be prevented. After completion of the heating, the air hole 31d can be switched to a pressurized state to separate the preform 10 from the upper heating surface 31a.

  Conversely, it is also possible to heat the preform 10 from the lower side using only the lower heating element 32. Also in this case, air holes 32d are formed in the lower heat generation surface 32a as shown by imaginary lines in FIG. 5 (a), and the preform 10 during contact heating is securely in close contact with the lower heat generation surface 32a. May be supported by

  It is also possible to provide such air holes 31d and 32d in both of the upper heating surface 31a and the lower heating surface 32a shown in FIG.

(Specific configuration of blow molding apparatus)
FIG. 6 is a plan view showing a specific configuration example of a blow molding apparatus for manufacturing the bottomed container 1 by subjecting the preform 10 having the above configuration to biaxial stretch blow molding. The blow molding apparatus 40 includes a supply station 41 to which the preform 10 is supplied from the outside. An annular carrier 42 for holding and transporting the preform 10 is waiting at the supply station 41. 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 at the same time. Each carrier 42 carries a preform 10 as shown in FIG.

  The carrier 42 carrying the preform 10 is transported along the supply path 43, which is a linear transport path, and delivered to the heating station 44. The heating station 44 has, for example, on the circular outer peripheral edge of the disk-like horizontal rotary plate 45, a carrier conveyance groove 45a formed of semicircular concave portions at a constant pitch in the circumferential direction. The carriers 42 attached to the carrier conveyance grooves 45 a are conveyed along the circular conveyance path 46 as the horizontal rotary plate 45 rotates.

  In the transport path 46, a portion that intersects the downstream end of the linear supply path 43 extending from the supply station 41 is a preform loading position 47. At the side of the preform loading position 47, a loading star wheel 48 is disposed. With the rotation of the loading star wheel 48, the transfer recess 48a formed on the outer peripheral surface receives the carrier 42 from the supply passage 43, and the carrier transfer located at the preform loading position 47 of the circular transfer passage 46 The carrier 42 is delivered to the groove 45a.

  The carrier 42 charged into the circular conveyance path 46 from the preform introduction position 47 reaches the preform delivery position 51 sequentially via the heating element contact position 49 and the heating element detachment position 50 in the middle of the conveyance path. The preform 10 carried on the carrier 42 is conveyed from the heating element contact position 49 to the heating element removal position 50, and the upper heating surface 31a of the upper heating element 31 and the lower heating element 32 from the top and the bottom It is gripped between the heat generating surfaces 32 a and is in close contact with them. In this state, the preform 10 is contact heated from both sides (see FIG. 5).

  A delivery star wheel 52 is disposed on the side of the preform delivery position 51 of the circular transport path 46. The carrier 42 carrying the preform 10 is fed from the preform delivery position 51 to the pitch conversion mechanism 54 via the delivery path 53 which is a linear conveyance path by the delivery star wheel 52. The pitch conversion mechanism 54 includes four pitch conversion arms 55 that receive the carrier 42 delivered from the delivery path 53 as 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 biaxial stretching blow molding is performed. Spread on a suitable pitch. In this state, the four carriers 42 are delivered to the blow molding station 57 four by four.

  The blow molding station 57 is a 4-packing station, and the blow molding die 58 includes four molding cavities 58 a formed at a constant pitch along the straight conveyance path 59. The preform 10 carried by each carrier 42 positioned in each cavity 58 a is subjected to biaxial stretch blow molding after clamping, and is made into a 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.

  At the product discharge station 60, a product recovery mechanism 62 is disposed which discharges the bottomed container 1 upward from the carrier 42 and reverses it, and discharges the bottomed container 1 to the linear product discharge passage 61 in an upright posture. The product recovery mechanism 62 is provided with four arms 62a, and the container opening 3 of each bottomed container 1 is gripped by the opening and closing chucks 62b at the end of the arms 62a. Then, the bottomed container 1 is discharged to the product discharge passage 61 located on the opposite side by turning in the vertical direction around the horizontal rotation shaft 62c. The bottomed container 1 is discharged to the discharge side along the product discharge passage 61 and collected at a predetermined place.

The empty carriers 42 after the bottomed container 1 has been collected are each four horizontal turntables 6.
3 rotates 180 degrees and is 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 delivery station 41. The empty carrier 42 supplied to the preform supply station 41 stands by there and waits for supply of the preform 10.

  FIG. 7 (a) is a schematic plan view showing the heating station 44 taken out, and FIG. 7 (b) is a conceptual view showing an elevation mechanism of the lower heating element 32. As shown in FIG.

  At the heating station 44, carrier conveyance grooves 45a for conveying the carrier 42 along the circular conveyance path 46 are formed on the outer peripheral edge of the horizontal rotary plate 45 at regular intervals in the circumferential direction. An upper heating element 31 and a lower heating element 32 (not shown) are disposed above and below the carrier conveyance grooves 45a, respectively. The heating elements 31, 32 rotate around the vertical center line 45b integrally with the horizontal rotation plate 45 by the heating element rotation mechanism 70. Therefore, each heating element 31, 32 moves along the circular transport path 46 together with each carrier 42.

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

  As the heat generating body lifting mechanism 80, for example, as shown in FIG. 7 (b), it can be composed of a cam mechanism 90 and a heat generating body rotating mechanism 70. The cam mechanism 90 includes a cam member 92 having a cam surface 91 formed along the transport 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. Is equipped.

  In this case, it is desirable to have a rotation mechanism 94 for rotating the cam member 92 about the vertical rotation axis 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 removal position 50 on the conveyance path 46 defined by the cam surface 91 of the cam member 92 It can be moved to the 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 be comprised similarly.

Reference Signs List 1 bottomed container 1a container center axis 2 container body 3 container mouth 4 mouth flange 5 mouth flange 5 inner surface 7 outer surface 10 outer surface 10 preform 11 center axis 12 plate-like body 13 edge 14 edge flange 15 Edge narrowed portion 16 First surface 16a Concave surface 16b First plane 17 Second surface 17a Convex surface 21 Preform conveyance path 22 Blow molding die 23 Preform carrier 23a Top 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 curved surface portion 32c Flat portion 32d Air hole

Claims (14)

In order to perform biaxial stretch blow molding on a preform made of a thermoplastic resin to produce a bottomed cylindrical container having a mouth flange, the preform can be molded to be capable of the biaxial stretch blow molding A method of heating a preform, wherein the preform is heated to a temperature,
The preformed body is subjected to the biaxial stretch blow molding to be a plate-like main body portion which becomes a bottomed container main body portion of the bottomed cylindrical container, and the biaxial stretch blow molding is not applied. And an edge flange which becomes an opening flange,
The plate-like main body includes a first surface which is an inner surface of the container main body, and a second surface which is an outer surface of the container main body.
Using a heating element provided with a heating surface having a shape complementary to that of one of the first surface and the second surface of the plate-like main body,
Relative to the surface of the plate-like body portion of the preform, from the lower side or upper side the heat generating surface of the heat generating element, by tightly by vacuum suction, and the plate-like main body portion is supported by the heat generating surface Form a close state,
A method for heating a preform , wherein the plate-like 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 1, wherein the surface of the plate-like main body is heat-sterilized by performing the contact heating . The first surface of the plate-like main body portion is defined by a concave surface which is a deepest portion at a position on a central axis of the preform, and a first plane which extends outward from an outer peripheral edge of the concave surface.
The second surface of the plate-shaped body portion, the heating method of the preform according to claim 1 or 2 is defined by a convex curved surface becomes the top in the position of the central axis. The thickness of the plate-like main body is
The portion defined by the first plane and the convex surface gradually increases from the outer peripheral portion on the side of the edge flange toward the central axis,
The method according to claim 3 , wherein a central portion defined by the concave surface and the convex surface is maintained at a constant maximum thickness . In order to perform biaxial stretch blow molding on a preform made of a thermoplastic resin to produce a bottomed cylindrical container having a mouth flange, the preform can be molded to be capable of the biaxial stretch blow molding A method of heating a preform, wherein the preform is heated to a temperature,
The preformed body is subjected to the biaxial stretch blow molding to be a plate-like main body portion which becomes a bottomed container main body portion of the bottomed cylindrical container, and the biaxial stretch blow molding is not applied. And an edge flange which becomes an opening flange,
A first heat generating body provided with a first heat generating surface having a shape complementary to a first surface on one side of the plate-like main body to be an inner surface of the container main body as a heat generating body; Using a second heating element provided with a second heating surface of a shape complementary to the second surface on the other side of the plate-like main body which is the outer surface of
The first, by sandwiching the plate-shaped body portion between the second heat generating surface, the first heat generating surface is close to the first surface, close to the second heat generating surface it was in close contact with the second surface Form a state ,
A method for heating a preform, wherein the plate-like main body is contact-heated to the molding temperature without thermal deformation while maintaining the close contact state.   The method according to claim 5, wherein the contact heating is performed to heat and sterilize the first and second surfaces of the plate-like main body. The first surface of the plate-like main body portion is defined by a concave surface which is a deepest portion at a position on a central axis of the preform, and a first plane which extends outward from an outer peripheral edge of the concave surface.
The method according to claim 5 or 6 , wherein the second surface of the plate-like main body portion is defined by a convex curved surface which is a top at a position on the central axis. The thickness of the plate-like main body is
The portion defined by the first plane and the convex surface gradually increases from the outer peripheral portion on the side of the edge flange toward the central axis,
The method according to claim 7, wherein the central portion defined by the concave surface and the convex surface is maintained at a constant maximum thickness. The preform includes a constricted portion which is bent from the inner peripheral edge of the edge flange toward the second surface and connected to the outer peripheral edge of the plate-like main body.
The preform according to claim 7 or 8, wherein the constricted portion is a portion not to be subjected to the biaxial stretch blow molding but to be a container constricted portion directly connected to the opening flange of the bottomed cylindrical container. Heating method. Wherein the preform the edge frame-like conveyance member having a flange support surface for mounting a flange to form a state of carrying the preform,
In this state, the transport tool is transported along the predetermined path to the heating element contact position,
Bringing the heating element into contact with the plate-like main portion of the preform on the transfer tool at the heating element contact position;
Conveying the heating element brought into contact with the preform together with the transfer tool along a predetermined path to a heating element removal position;
Releasing the heating element from the preform at the heating element release 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 mold for biaxial stretch blowing,
A bottom characterized by subjecting the plate-like main body of the preform to biaxial stretching blow in a state where the blow mold is closed and the edge flange of the carrier and the preform is nipped. Method of manufacturing a cylindrical container. A preform for use in the manufacture of a bottomed cylindrical container having a mouth flange, which is supplied to a blow mold for biaxial stretch blow at a temperature capable of being subjected to biaxial stretch blow moldability. ,
A plate-like main body portion which is subjected to biaxial stretch blow molding to be a bottomed container main body portion of the bottomed tubular container, and the above-mentioned tubular container with the bottom is not subjected to the biaxial stretch blow molding With an edge flange that becomes the mouth flange,
One surface of the plate-like main body is a first surface to be an inner surface of the container main body, and the other surface is a second surface to be an outer surface of the container main body,
At least one of the first surface and the second surface is a portion that is contact-heated by a heating element such that the plate-like main body is in a state of being heated to the molding temperature,
The first surface of the plate-like main body is defined by a concave surface which is a deepest portion at a position on a central axis of the plate-like main body, and a first flat surface extending outward from an outer peripheral edge of the concave surface. ,
The preform for manufacturing a bottomed cylindrical container, wherein the second surface of the plate-like main body portion is defined by a convex curved surface which becomes a top at a position on the central axis. The thickness of the plate-like main body is
The portion defined by the first plane and the convex surface gradually increases from the outer peripheral portion on the side of the edge flange toward the central axis,
The preform for producing a bottomed tubular container according to claim 12, wherein a central portion defined by the concave surface and the convex surface is maintained at a constant maximum thickness. And a neck portion which is bent from the inner peripheral edge of the edge flange toward the second surface and connected to the outer peripheral edge of the plate-like main body,
The bottomed cylindrical portion according to claim 12 or 13, wherein the narrowed portion is a portion which is not subjected to the biaxial stretch blow molding but is directly connected to the opening flange of the bottomed cylindrical container. Preforms for container production.

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