JP4871686B2 - Method for producing double wall blow molded body - Google Patents

Description

The present invention relates to a method for producing a double-wall blow molded article comprising an inner blow molded article and an outer blow molded article.

This type of double wall blow molded article (specifically, a double wall container) and a method for producing the same are described in Patent Documents 1 to 4 below.
In Patent Documents 1 and 2, the inner and outer parisons are extruded simultaneously, air is blown into the space inside the inner parison and the space between the inner and outer parisons, and the outer parison is blown into a shape along the inner surface of the mold cavity. It is described that the inner parison is blow-molded into a desired shape by molding and a difference in blown air pressure.
In Patent Document 3, the inner and outer parisons are extruded at the same time, air is sealed in the space between the inner parison and the outer parison, and then the air is blown into the space inside the inner parison so that the outer parison is shaped along the inner surface of the mold cavity. And blow molding the inner parison into a desired shape by the difference between the air pressure in the inner parison and the air pressure of the air enclosed in the space between the inner and outer parisons.
In Patent Document 4, when a bottomed parison is inserted into the inside of a molded outer container and air is blown into the inside of the parison for blow molding, a longitudinal rib or a peripheral rib is provided on the outer blow molded body, It describes that a double-walled container having a gap between an outer container and an inner container is manufactured by providing vertical ribs or peripheral ribs on a bottomed parison.

Japanese Examined Patent Publication No. 44-16795 Japanese Patent Publication No. 44-17279 JP-A-2005-74815 JP 2005-59865 A

However, in Patent Documents 1 to 3, it is described that the inner parison expands at a uniform interval from the outer parison. However, since the parison that receives air pressure expands into a substantially spherical shape, the inner parison is referred to as the outer parison. In reality, it is impossible to inflate into a cylindrical shape with a uniform spacing.
This is also the case with the method of Patent Document 4. Further, when a longitudinal rib or a peripheral rib is provided in the parison, uneven thickness is positively introduced, so that the thin portion expands preferentially and the bottomed parison expands. When the outer blow molded body is provided with longitudinal ribs or peripheral ribs, there is a problem that the expanded parison enters between the longitudinal ribs or the peripheral ribs.
Therefore, in any case, the shape of the manufactured inner container is indeterminate, and it is impossible to accurately control this.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to obtain a double-wall blow molded article having an accurate shape of an inner blow molded article and an outer blow molded article.

In the method for producing a double wall blow molded article according to the present invention, an inner blow molded article shaped in advance by blow molding is disposed between open blow molding dies, and an outer side of the inner blow molded article is arranged. The cylindrical parison is lowered to close the blow molding die and clamped. At this time, a part of the parison is pressed against the inner blow molded product by the blow molding die. It is welded to the surface at a plurality of locations, and subsequently, pressurized air is blown into the space between the parison and the inner blow molded body and the space inside the inner blow molded body by separate blowing needles, There is no flow of pressurized air between the two spaces partitioned by the inner blow molded body, only the parison is blow molded to form an outer blow molded body, and the inner blow molded body and the space Side blow molded article is that the production of two connected double wall blow molded article by a plurality of ribs.
In the above manufacturing method, the pressure of the pressurized air blown into the inner blow molded body is made equal to or higher than the pressure of the pressurized air blown between the parison and the inner blow molded body. By setting the inside / outside air pressure in this way, the inner blow molded body is not reduced, and a part of the parison can be reliably pressed and welded to the inner blow molded body by the cavity inner surface of the blow molding die.

  As a specific form of the manufacturing method, (1) a protrusion is provided on the inner surface of the cavity of the blow molding die to press the parison toward the inner blow molded body, and the parison of the inner blow molded body is formed by the protrusion. Welding to the surface, thereby forming one or more of the ribs; (2) when the blow molding die is advanced and retracted toward the inner blow molded body, and the tip of the blow molding die is blow molded Including a slide mold that forms part of the inner surface of the cavity of the mold, the slide mold is advanced to press and weld the parison against the surface of the inner blow molded body, and then retracted, whereby 1 of the ribs (3) The inner blow molded body has one or a plurality of plate-shaped ribs formed along the split part, and the plate-shaped rib is an outer side. The inner blow molded body is arranged between the blow molding dies so as to align with the mold part of the low molded body, and when the mold is clamped, the parison is pressed against the plate rib from both sides by the blow molding dies. For example, the plate-like rib may be sandwiched between the parisons and welded to the plate-like rib. The methods (1) to (3) can be combined.

The double-wall blow molded body manufactured by the above manufacturing method is composed of an inner blow molded body and an outer blow molded body surrounding the outer periphery with a gap, and the inner and outer blow molded bodies are connected by ribs, and the outer blow molded body A hole for air blowing is formed in the body.
As a specific example of the double wall blow molded article, the double wall blow molded article produced by the above production method (particularly the method of (1) above) is between the inner blow molded article and the outer blow molded article. A bottomed cylindrical rib is formed which extends from the wall portion of the outer blow molded body toward the outer periphery of the inner blow molded body and has a tip welded to the surface of the inner blow molded body. Further, the double wall blow molded body manufactured by the above manufacturing method (particularly the method of (2) above) is provided between the inner blow molded body and the outer blow molded body from the wall portion of the outer blow molded body. A hidden rib is formed which extends toward the outer periphery of the blow molded body and has a tip welded to the surface of the inner blow molded body. Furthermore, the double-wall blow molded product manufactured by the above manufacturing method (particularly the method of (3) above) comprises an inner blow molded product and an outer blow molded product surrounding the outer periphery with a gap, and the inner blow molded product. Plate-shaped ribs are formed along the mold part of the molded body, and a part of the plate-like ribs are sandwiched between the resins of the outer blow molded body and welded to each other at the mold part of the outer blow molded body. . Two or three types of ribs may be formed on one double wall blow molded article.

According to the present invention, it is possible to obtain a double wall blow molded body having an accurate shape both inside and outside and connected by a rib at a predetermined interval and consisting of an inner blow molded body and an outer blow molded body.
This double wall blow molded article has excellent heat insulation properties. For example, when applied to a bottle or a duct for air conditioning, the bottle surface does not have to be wrapped with a foam or a nonwoven fabric containing air as in the prior art, or on the duct surface. Condensation can be prevented without attaching a urethane foam resin. If necessary, the heat insulation can be further enhanced by encapsulating, for example, a granular foam heat insulating material in the gap between the inner blow molded body and the outer blow molded body.

Hereinafter, with reference to FIGS. 1-11, the manufacturing method of the double wall blow molding which concerns on this invention is demonstrated concretely.
FIG. 1 shows a double wall blow molded body (double wall duct) obtained by the method of the present invention. This double wall blow molded article is composed of an inner blow molded article 1A having a substantially rectangular cross section and an outer blow molded article 2 having a substantially rectangular cross section and surrounding the outer periphery of the inner blow molded article 1A with a gap. However, in this double-wall blow molded body, the outer blow molded body 2A is tightly welded to the outer periphery of the inner blow molded body 1A with both ends 2a being squeezed. The narrowed end portions 2a are used for connecting the double wall blow molded bodies to each other or the double wall blow molded body and other members via a joint or the like.

  Solid plate-like ribs 4 and 5 (the plate-like ribs 5 are not shown in FIG. 1) are formed on the parting portion 3 of the inner blow molded body 1A, and a part (tip portion) of the plate-like ribs 4 and 5 is formed. ) Is sandwiched between the resins of the outer blow molded body 2A at the mold part 6 of the outer blow molded body 2A (aligned with the mold part 3 of the inner blow molded body 1). 5 and the resin are welded to each other. More specifically, solid plate-like ribs 7 and 8 (the plate-like ribs 8 are not shown in FIG. 1) are formed in the split portion of the outer blow molded body 2A. 5 is sandwiched between the resin of the plate-like ribs 7 and 8.

A bottomed cylindrical rib 9 extending from the wall portion of the outer blow molded body 2A and reaching the outer periphery of the inner blow molded body 1A is formed on a surface different from the surface of the mold part 6 of the outer blow molded body 2A. The tip is welded to the surface of the inner blow molded body 1A. The same bottomed cylindrical rib (not shown) is also formed on the surface opposite to the surface on which the rib 9 is formed.
Since these ribs 4, 5, and 9 are formed on the side walls of the inner blow molded body 1A or the outer blow molded body 2A, the ribs 4, 4 are interposed between the inner blow molded body 1A and the outer blow molded body 2A. A fixed gap is maintained by 5 and 9, and the inner blow molded body 1A is stably disposed at a predetermined position in the outer blow molded body 2A.
Conventional air-conditioning ducts have a problem in that urethane foam or the like is pasted around to keep heat insulation and prevent condensation, and it is time consuming and the ducts cannot be recycled. However, the double wall duct according to the present invention can maintain heat insulation and prevent condensation without using urethane foam or the like.

The manufacturing method of this double wall blow molded body will be described with reference to FIGS.
First, as in normal blow molding, a thermoplastic resin parison 14 is extruded from the first extrusion die 11 between a pair of opened first blow molding dies 12, 13, and the first blow molding die 12, The air blowing needle 15 installed under 13 is raised and inserted into the parison 14, and the mold is clamped and blow-molded as shown in FIG. Thereby, the parison 14 is shape | molded in the shape along the cavity surface of the 1st blow molding metal mold | die 12,13.

After molding, the first blow molds 12 and 13 are opened. As shown in FIG. 3, the cavity surface of the first blow molding die 12 is formed with recesses 16 and 17 for forming plate-like ribs 4 and 5 along the parting surface 3. A recess 18 for accommodating the air blowing needle 15 is formed on the mold dividing surface of the mold 12. The cavity surface and the parting surface of the first blow molding die 13 are also symmetrical with the first blow molding die 12. Reference numeral 19 denotes a blow molded article.
Subsequently, as shown in FIG. 4, the burr 21 is removed from the blow molded body 19 to obtain the inner blow molded body 1. In the inner blow molded body 1, plate-like ribs 4, 5 are formed along the parting surface 3, and a pipe-like blowing port 22 formed around the blowing needle 15 is left. The blowing needle 15 and the blowing port 22 are used as a support member for the inner blow molded body 1 and for blowing air into the inner blow molded body 1 in forming the outer blow molded body 2.

Adjacent to the first extrusion die 11 and the first blow molds 12 and 13 for molding the inner blow molded body 1, the second extrusion die 23 and the pair of second blow molds for molding the outer blow molded body 2. 24 and 25 are installed, and the blowing needle 15 is installed so as to be horizontally movable therebetween. As shown in FIG. 5, the cavity surface of the second blow mold 24 accommodates the tips of the plate-like ribs 4, 5 formed on the inner blow molded body 1, and the mold is formed on the outer blow molded body 2. Concave portions 26 and 27 for forming the plate-like ribs 7 and 8 are formed along the split surface 6, and a concave portion 29 for accommodating the air blowing needle 28 is formed on the split surface of the second blow molding die 24. Has been. Further, on the cavity surface of the second blow molding die 24, a protrusion 31 for forming a bottomed cylindrical rib (rib corresponding to the rib 9) on the outer blow molded body 2 and step portions 32 and 33 are formed. ing. The cavity surface and the split surface of the second blow molding die 24 also have a symmetric shape.
A hole is formed in the recess 27 of the second blow molding die 24, and a rod-shaped slide die 34 that can be advanced and retracted is disposed in the hole (the same applies to the recess 26). The slide die 34 moves forward after clamping and forms a hole in the parison sandwiched in the recess 27.

As shown in FIG. 5, the blowing needle 15 is moved between the second blow molds 24 and 25, and the blowing port 22 of the inner blow molded body 1 from which burrs have been removed is put on the blowing needle 15 and set in place. Subsequently, as shown in FIG. 6, a parison 35 made of a thermoplastic resin having compatibility with the resin of the inner blow molded body 1 is provided between the second extrusion die 23 and the second blow molding dies 24 and 25. extrusion, lowering the parison 35 to the outside of the inner blow molded article 1, further clamping to close the blow mold 24, 25 as shown in FIG. 7, the needle 15 is blown into the space inside the blow-molded body 1 Blow molding is performed by blowing pressurized air into the space in the parison 35 (between the parison 35 and the inner blow-molded body 1) and blowing the pressurized air from the blow needle 28. The two spaces are partitioned by the inner blow molded body 1, and there is no flow of pressurized air between the two spaces.
By this clamping, the plate-like ribs 4 and 5 are sandwiched between the parisons 27, the plate-like ribs 4 and 5 and the parison 27 are welded, and the plate-like ribs 7 and 8 are formed. 9 is formed and welded to the surface of the inner blow molded body 1, and further, the parison 27 is welded to the upper and lower ends of the inner blow molded body 1, and the parison 27 becomes the cavity of the second blow molds 21 and 22 by blow molding. It is formed into a shape along the surface. Note that only the parison 27 is molded by this blow molding, and the inner blow molded body 1 is not blow molded and maintains its original shape.

After the molding, the second blow molding dies 24 and 25 are opened as shown in FIG. 8, and the blow molded body 36 containing the inner blow molded body 1 is taken out. Plate-shaped ribs 7 and 8 and bottomed cylindrical ribs 9 are formed in the blow molded body 36, and holes 37 are formed in the plate-shaped ribs 7 and 8.
Subsequently, as shown in FIG. 9A, the burr 38 is removed from the blow molded body 36 to obtain the outer blow molded body 2 (with the inner blow molded body 1 accommodated therein), and further shown in FIG. 9B. Thus, by cutting off the upper and lower ends, a double wall blow molded body (shown in FIG. 1) composed of the inner blow molded body 1A and the outer blow molded body 2A is obtained. In this double wall blow molded body, the marks of the blow needles 28 are left as holes 39.

In the above example, the bottomed cylindrical rib has a racetrack cross section (in a cross section perpendicular to the length direction), but a circular cross section (a frustoconical rib), an elliptical cross section (a truncated ellipse). A conical rib), a polygonal cross-section (a truncated pyramid-shaped rib), or other closed cross-sectional shapes can be used arbitrarily.
In the above example, a protrusion reaching the surface of the inner blow molded body when the mold is clamped is formed on the cavity surface of the second blow mold, and the surface of the inner blow molded body is formed on the outer blow molded body by the protrusion. Has formed a bottomed cylindrical rib, such as described in JP-A-6-71738, for example, the tip is part of the cavity surface of the second blow mold, when retracted, A slide mold is provided in the second blow mold so that the tip reaches the vicinity of the surface of the inner blow molded body when it advances, and after clamping, the slide mold is advanced to bring the parison to the surface of the inner blow molded body. It can also be pressed and welded, and then retracted, thereby forming a so-called hidden rib. As the hidden rib, a plate-like or rod-like one can be formed.

  FIG. 10 shows another double wall blow molded body (double wall duct) obtained by the method of the present invention. This double-wall blow molded body has an inner blow molded body 41 having a flat and substantially rectangular cross section, and an outer blow mold having the same flat and substantially rectangular cross section and surrounding the outer periphery of the inner blow molded body 41 with a gap. It consists of a body 42. The inner blow molded body 41 is open at one end in the length direction (left side in FIG. 10), and the narrowed end of the outer blow molded body 42 is welded to the entire circumference of the end. The other ends of the inner blow molded body 41 and the outer blow molded body 42 are closed. In this example, a hole is drilled in one wide side wall of the outer blow molded body 42, and a hole of the same size is also drilled in the wide side wall of the inner blow molded body 42 below the hole. A cylindrical air guide member 43 (with a wind direction plate 44 installed therein) is installed in the hole, and air flowing into the inner blow molded body 42 from one open end is passed through the air guide member 43. It comes to blow out.

  A plurality of solid plate-like ribs 45 are formed along the parting part of the inner blow-molded body 41, and a part (tip part) of the plate-like rib 45 is a parting part (inner-blow molding) of the outer blow-molded body 42. The plate-like rib 45 and the resin are welded to each other between the resin of the outer blow molded body 42. Solid plate-like ribs 46 are formed on the outer blow-molded body 42 along the split part at the plate ribs 45 of the inner blow-molded body 41 (only two locations). The ribs 45 are sandwiched between the resin of the plate-like ribs 46. This is the same as the structure of the plate-like ribs 4 and 5 formed on the inner blow-molded body 1 of the double wall blow-molded body shown in FIG. 1 and the plate-like ribs 7 and 8 formed on the outer blow-molded body 2. It is. On the other hand, in other locations of the plate-like ribs 45 of the inner blow-molded body 41, the large plate-like ribs 46 are not formed on the outer blow-molded body 42, and the resin of the outer blow-molded body 42 is replaced by the plate-like ribs 45. A plate-like rib 47 that is welded to the plate-like rib 45 in such a manner as to sandwich the tip of the plate (or along the plate-like rib 45) is formed along the parting portion. .

Further, the outer blow molded body 42 has a bottomed cylindrical shape that extends from the wall portion of the outer blow molded body 42 and reaches the outer periphery of the inner blow molded body 41, and its tip is welded to the surface of the inner blow molded body 41. The rib 48 is formed (only the front side is shown, but it is also formed on the back side). The bottomed tubular rib 48 is the same as the bottomed tubular rib 9 of the double wall blow molded article shown in FIG.
A fixed gap is formed between the inner blow molded body 41 and the outer blow molded body 42 by the plate-like ribs 45 and the bottomed cylindrical rib 48 formed on the side walls of the inner blow molded body 41 and the outer blow molded body 42. The inner blow molded body 41 is stably disposed at a predetermined position in the outer blow molded body 42.
Reference numeral 49 denotes an air blowing hole, which corresponds to the hole 39 of the double wall blow molded body shown in FIG. Reference numeral 50 denotes a concave portion formed in the inner blow molded body 41. The concave portion 50 can be used when a duct or other member having a convex portion corresponding to the concave portion 50 is connected to the double wall blow molded body.

This double wall blow molded article can be manufactured in substantially the same manner as the double wall blow molded article shown in FIG. That is, first, the inner blow molded body 41 is molded, the inner blow molded body 41 is disposed between the blow molds, the cylindrical parison is lowered to the outside of the inner blow molded body 41, and the blow mold is formed. The mold is closed and clamped. At this time, a part of the parison is pressed against the inner blow-molded body 41 with a projection formed on the cavity inner surface of the blow molding die, and between the parisons forming the plate-like ribs 46 or 47. Sandwiching the plate-like ribs 45 of the inner blow molded body 41, thereby causing the parison to be welded to the surface of the inner blow molded body 41, and subsequently the space (from the hole 49) between the parison and the inner blow molded body 41, and Pressurized air is blown into the space inside the inner blow molded body 41 (from the bottom in the same manner as the double wall blow molded body shown in FIG. 1), and the parison is blow molded.

FIG. 11 shows another double wall blow molded article (double wall bottle) obtained by the method of the present invention.
This double-wall blow molded body has a bottle-shaped inner blow molded body 51 composed of a mouth tube portion, a shoulder portion following it, a cylindrical body portion, and a bottom portion, and also has a bottle shape. The outer blow molded body 52 is surrounded by a gap.
The mouth tube portion of the outer blow molded body 52 is in close contact with and welded to the mouth tube portion of the inner blow molded body 51, as in the double wall bottles disclosed in Patent Documents 1 to 4.
A plate-like rib 53 is formed along the mold part at the bottom of the inner blow-molded body 51. In the outer blow-molded body 52, the resin of the mold part at the bottom sandwiches the plate-like rib 53 (or A plate-like rib 54 which is welded to the plate-like rib 53 in a shape (like the plate-like rib 53) and protrudes slightly is formed along the mold part. This form is similar to the relationship between the plate-like ribs 45 and 47 of the double wall blow molded article shown in FIG.

Further, the outer blow molded body 52 has a bottomed cylindrical shape that extends from the wall portion of the outer blow molded body 52 and reaches the outer periphery of the inner blow molded body 51, and the tip thereof is welded to the surface of the inner blow molded body 51. The rib 55 is formed. The bottomed cylindrical rib 55 is the same as the bottomed cylindrical rib 9 of the double wall blow molded article shown in FIG.
A fixed gap is maintained between the inner blow molded body 51 and the outer blow molded body 52 by the plate-like ribs 53 and the bottomed cylindrical rib 55 formed on the side wall. The blow molded body 52 is stably disposed at a predetermined position.
Reference numeral 56 denotes an air blowing hole, which corresponds to the hole 39 of the double wall blow molded body shown in FIG.

This double wall blow molded article can be manufactured in substantially the same manner as the double wall blow molded article shown in FIG. That is, first, the inner blow molded body 51 is molded, the inner blow molded body 51 is disposed between the blow molds, the cylindrical parison is lowered to the outside of the inner blow molded body 51, and the blow mold is formed. The mold is closed and clamped. At this time, a part of the parison is pressed against the inner blow molded body 51 by the protrusion formed on the cavity inner surface of the blow mold, and the inner blow is formed between the parisons forming the plate-like ribs 54. The plate-like rib 53 of the molded body 51 is sandwiched so that the parison is welded to the surface of the inner blow molded body 51, and then the space (from the hole 56) between the parison and the inner blow molded body 51, and the inner blow Pressurized air is blown into the space inside the molded body 51 (from the mouth tube portion) to blow-mold the parison.

FIG. 2 is a cutaway perspective view of a part of a double wall blow molded article (a part of an outer blow molded article) manufactured by the method of the present invention. It is a figure explaining the manufacturing process of the double wall blow molding object in order. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. It is a figure explaining a manufacturing process in order similarly. FIG. 6 is a cutaway perspective view of a part of another double wall blow molded article (a part of the outer blow molded article) manufactured by the method of the present invention. It is a notch perspective view of a part of another double wall blow-molded product manufactured by the method of the present invention (a part of the outer blow-molded product).

Explanation of symbols

1, 1A, 41, 51 Inner blow molded body 2, 2A, 42, 52 Outer blow molded body 3, 6 Split part 4, 7, 45, 47, 53, 54 Plate-shaped rib 9, 48, 55 Bottomed cylinder Shaped ribs 14,35 parison

Claims (4)

An inner blow molded body shaped in advance by blow molding is placed between the opened blow molding molds, a cylindrical parison is lowered to the outside of the inner blow molded body, and the blow molding mold is The mold is closed and clamped. At this time, a part of the parison is pressed against the inner blow molded body by the blow molding die and welded to the surface of the inner blow molded body at a plurality of locations, and then the parison and the inner Pressurized air is blown into the space between the blow molded bodies and the space inside the inner blow molded body by separate blowing needles, and the pressure of the pressurized air blown into the inner blow molded body at this time , aforementioned parison and higher than that equal to or a pressure of the pressurized air blown between the inner blow molded article, also with one another between the two spaces partitioned by the inner blow molded article at this time A double-wall blow molded body in which there is no flow of compressed air, only the parison is blow molded to form an outer blow molded body, and the inner blow molded body and the outer blow molded body are connected by a plurality of ribs. A method for producing a double-wall blow-molded product, characterized by comprising: A protrusion for pressing the parison toward the inner blow molded body is installed on the inner surface of the cavity of the blow molding die, and the parison is welded to the surface of the inner blow molded body by the protrusion, whereby one of the ribs Alternatively, a method for producing a double wall blow molded article according to claim 1, wherein a plurality of them are formed. The blow molding die includes a slide die that advances and retreats toward the inner blow molded body, and a tip of the blow molding die forms a part of the cavity inner surface of the blow molding die, and advances the slide die. The double wall according to claim 1, wherein the parison is pressed against the surface of the inner blow molded body to be welded, and subsequently retracted, thereby forming one or more of the ribs. A method for producing a blow molded article. The inner blow-molded body has one or a plurality of plate-shaped ribs formed along the mold part, and the inner blow-molded product is aligned with the mold part of the outer blow-molded body. When the body is placed between the blow molding dies and clamped, the parison is pressed against the plate ribs from both sides by the blow molding die, and the plate ribs are sandwiched between the parisons. The method for producing a double wall blow molded article according to claim 1, wherein welding is performed.

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