JP2017080962A - Method for manufacturing double structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a double structure highly flexible in design, which is excellent in mass productivity and capable of suppressing manufacturing cost.SOLUTION: Each of a pair of resin sheets is shaped by being vacuum-suctioned from a cavity surface of a mold; the mold is clamped while an inner-side molded body molded in advance is disposed between the pair of resin sheets to integrate the pair of shaped resin sheets for molding an outer-side molded body; and the inner-side molded body is disposed inside the outer-side molded body with a prescribed space. For example, a rib extended out from the inner-side molded body is formed when molding the inner-side molded body and the rib is integrated with the outer-side molded body for disposing and integrating the inner-side molded body inside the outer-side molded body with the prescribed space.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a method for manufacturing a double structure in which an inner molded body is arranged with a predetermined gap in an outer molded body.

  For example, in the field of automobile ducts, a foam molded body in which a flange portion for connecting to another tubular member is provided in the vicinity of an opening in a tube main body is widely used. In particular, in a duct for ventilating air from an air conditioner, it is possible to realize a lightweight duct having excellent heat insulation properties by using a tubular foamed molded body. Further, such a duct is more effective because it can further improve heat insulation and light weight by increasing the foaming ratio at the time of manufacture and increasing the number of bubbles inside the foam.

  As a method for producing such a foam-molded product, a method of molding a molten resin by clamping with a split mold is widely known. In recent years, with the improvement of molding technology, mass production with an improved expansion ratio of tubular foams is becoming possible.

  However, there is a limit to increasing the expansion ratio, and it is actually difficult to dramatically improve the heat insulation and weight reduction by simply increasing the expansion ratio. In addition, the improvement in the expansion ratio may cause a lack of rigidity, and it is assumed that a problem also occurs in this respect.

  From such a situation, a method of forming a double wall blow molded article by blow molding has also been proposed (see, for example, Patent Document 1). The double wall blow molded body has a configuration in which the outer blow molded body and the inner blow molded body are connected at a predetermined interval, so that heat insulation can be secured without increasing the foaming ratio of each molded body. It is thought that the effect of being able to be obtained.

  Specifically, in the invention described in Patent Document 1, an inner blow molded body previously blow-molded is placed between open blow molds, and a cylindrical parison is lowered outside the inner blow molded body. The blow molding die is closed and the mold is clamped. At this time, a part of the parison is pressed against the inner blow molded product by the blow molding die and welded to the surface of the inner blow molded product at a plurality of locations, and then the parison. Pressed air is blown between the inner blow molded body and the inside of the inner blow molded body, and a parison is blow molded to produce a double wall blow molded body in which the inner and outer blow molded bodies are connected by a plurality of ribs. It is described to do.

Japanese Patent No. 4871686

  However, since the outer blow molded body is blow-molded by using a cylindrical parison, the manufacturing method described in Patent Document 1 is difficult to mold itself, leaving various problems. For example, when an inner blow molded body is inserted into a cylindrical parison, if the cylindrical parison comes into contact with the inner blow molded body, it becomes a defective product. Therefore, when trying to improve productivity, defective products may occur frequently, and there are many problems in terms of mass productivity.

  In order to avoid this, if the inner diameter of the cylindrical parison is increased, burrs increase when forming the outer blow molded product, which is disadvantageous in terms of manufacturing cost. In addition, when the outer blow molded body and the inner blow molded body are integrated by blow molding, it is difficult to narrow the gap between the outer blow molded body and the inner blow molded body. .

  The present invention has been proposed in view of such a conventional situation, and is a novel dual structure (for example, two structures) that is excellent in mass productivity, can reduce manufacturing costs, and has a high degree of design freedom. It is an object of the present invention to provide a method for producing a heavy structure duct).

  In order to achieve the above-mentioned object, the method for producing a double structure (for example, a double structure duct) according to the present invention is shaped in advance by vacuum-suctioning a pair of resin sheets from the cavity surface of the mold. The mold is clamped in a state in which the molded inner molded body is disposed between the pair of resin sheets, thereby forming the outer molded body by integrating the pair of molded resin sheets and forming the outer molded body. The inner molded body is arranged with a predetermined gap inside the molded body.

  In the manufacturing method of the present invention, since the outer molded body is preliminarily shaped with a mold, the inner molded body is inserted therebetween, so that there is no occurrence of defects due to the parison contacting the inner molded body. Therefore, it is advantageous in terms of mass productivity. In addition, since the outer molded body can be molded from a resin sheet of an appropriate size, the generation of burrs is suppressed to the necessary minimum, leading to a reduction in manufacturing cost. Furthermore, since the space | interval of an inner side molded object and an outer side molded object can be set arbitrarily in the case of insertion of an inner side molded object, the freedom degree of design is high.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to manufacture the double structure (for example, double structure duct) which has the heat insulation excellent without raising foaming magnification, and is high in rigidity. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a double structure that is excellent in mass productivity, can reduce manufacturing costs, and has a high degree of design freedom.

It is a figure which shows the manufacturing process of a double structure duct, and shows the process of arrange | positioning the molten resin sheet for inner side molded object formation. It is a figure which shows the shaping process of the resin sheet for inner side molded object formation. It is a figure which shows the shaping | molding process of the inner side molded object by mold clamping. It is a schematic perspective view which partially fractures and shows the inner side molded object shape | molded. It is a figure which shows the arrangement | positioning process of the resin sheet for outer side molded object formation. It is a figure which shows the shaping process of the resin sheet for outer side molded object formation. It is a figure which shows the insertion process of an inner side molded object. It is a figure which shows the formation process of the double structure duct by mold clamping. It is a schematic perspective view which partially fractures and shows the double structure duct shape | molded. It is a figure which shows the processing process after secondary shaping | molding. It is a schematic sectional drawing which shows an example of the metal mold | die which enabled simultaneous molding of an inner side molded object and a double structure duct.

  Hereinafter, an embodiment in which the present invention is applied to manufacture of a double structure duct will be described in detail with reference to the drawings.

  The double-structured duct manufactured in the present embodiment is, for example, an automobile duct, and is a lightweight tubular molded body for circulating cool and warm air supplied from an air conditioner unit to a desired site.

  In order to manufacture a double-structured duct in the manufacturing method of this embodiment, the inner molded body is first molded, and then the outer molded body is molded and the outer molded body and the inner molded body are integrated. The inner molded body is molded into a duct shape smaller in size than the outer molded body, and the molding method is arbitrary. For example, it can be formed by blow-molding or forming two resin sheets by vacuum suction into a mold and then clamping.

  1 to 4 show an example of a molding process of the inner molded body (primary molding process). In this example, after forming the two resin sheets by vacuum suction into a mold, the inner molded body is formed by clamping the mold. That is, as shown in FIG. 1, two molten resin sheets 5, 6 made of thermoplastic resin or the like are arranged by facing dies 3, 4 having half-shaped cavities 1, 2 of the inner molded body. Is extruded from the T die and is suspended between the molds 3 and 4.

  After the molten resin sheets 5 and 6 are suspended, the molds 3 and 4 are moved forward toward the molten resin sheets 5 and 6. After the molds 3 and 4 and the molten resin sheets 5 and 6 are in contact with each other, air is sucked from a vacuum vent provided on the cavity surface of the molds 3 and 4, and as shown in FIG. Is closely attached to the cavity surface of the dies 3 and 4.

  In this way, the molten resin sheets 5 and 6 are brought into close contact with the cavity surfaces of the molds 3 and 4, and the resin sheets 5 and 6 are shaped into a shape along the surface of the cavity surfaces of the molds 3 and 4. As shown in Fig. 4, the molds 3 and 4 are further advanced to perform mold clamping.

  As a result of clamping, the pinch-off portions of the dies 3 and 4 abut against each other so that the cavities 1 and 2 of the two dies 3 and 4 are closed, and the peripheral portions of the resin sheets 5 and 6 are welded together. Thereby, a parting line is formed on the joining surface of the two resin sheets 5 and 6, and a hollow portion is formed inside the two resin sheets 5 and 6 to form a duct shape.

  Next, the molds 3 and 4 are moved away from each other to perform mold opening, the inner molded body 10 is taken out, and burrs on the outer peripheral portion are removed. Thereby, the inner side molded object 10 can be shape | molded.

  As shown in FIG. 4, the inner molded body 10 has a duct shape, and has a rib 11 for integration with an outer molded body described later. Although the formation method of the rib 11 is arbitrary, it can be easily formed by using a portion where the resin sheets 5 and 6 are compressed (welded). In this case, the rib 11 is formed along the parting line PL of the inner molded body 10.

  The shape, formation position, number of formations, etc. of the ribs 11 are arbitrary, and the shape, formation position, number of formations, etc. of the ribs 11 are also arbitrary as long as they can be supported with a predetermined gap with respect to the inner molded body 10 and the outer molded body. is there. For example, when the ribs 11 are formed along the parting line PL of the inner molded body 10, a plurality of ribs 11 may be arranged at predetermined intervals, or the longitudinal direction of the inner molded body 10 along the parting line PL. You may form continuously along. In addition, in order to stabilize the attachment state of the inner side molded object 10, it is preferable to form the rib 11 along the parting line PL of the both sides of the inner side molded object 10, respectively.

As the molding material of the inner molded body 10 (that is, the material of the resin sheets 5 and 6), a thermoplastic resin can be mainly used. As the thermoplastic resin, a polyolefin resin is preferable, and as the polyolefin resin, For example, polypropylene having a melt tension at 230 ° C. in the range of 30 to 350 mN can be used. As polypropylene, a propylene homopolymer, an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, and a mixture thereof can be used. Moreover, it is preferable to add a styrene-type elastomer or low-density polyethylene in the range of less than 40 mass% with respect to polyolefin resin. As the styrene-based elastomer, hydrogenated polymers such as styrene-ethylene / butylene-styrene block copolymer, styrene-ethylene / propylene-styrene block copolymer, styrene-butadiene random copolymer are used, and styrene elastomer styrene. The content is preferably less than 30% by mass. Further, as the low density polyethylene, those having a density of 0.91 g / cm ³ or less are used, and it is particularly preferable to use a linear ultra low density polyethylene polymerized by a metallocene catalyst.

  The inner molded body 10 may be a foam molded body formed by foaming a resin with a foaming agent, or may be a non-foamed body that is not foamed. In the case of a foamed foamed molded article, any of a physical foaming agent, a chemical foaming agent and a mixture thereof may be used as the foaming agent. As physical foaming agents, inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas, and water, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane, dichloroethane, and their supercritical fluids are used. be able to. As the supercritical fluid, carbon dioxide, nitrogen or the like is preferably used. If nitrogen is used, the critical temperature is 149.1 ° C. and the critical pressure is 3.4 MPa or more. If carbon dioxide is used, the critical temperature is 31 ° C. and the critical pressure is 7 It is obtained by setting it to 4 MPa or more.

  On the other hand, the outer molded body is molded by clamping the two resin sheets by vacuum suction into a mold. 5 to 10 show a molding process (secondary molding process) of a double structure duct by molding the outer molded body and integrating the inner molded body.

  In order to mold the outer molded body, as shown in FIG. 5, the molds 23 and 24 having the half-shaped cavities 21 and 22 of the outer molded body are opposed to each other as shown in FIG. The two molten resin sheets 25 and 26 made of thermoplastic resin or the like are pushed out from the T die and suspended between the molds 23 and 24. At this time, the shapes of the cavities 21 and 22 are set so that the inner diameter of the outer molded body is larger than the outer diameter of the inner molded body. In the double structure duct to be molded, the difference between the inner diameter dimension of the outer molded body and the outer diameter dimension of the inner molded body is the gap dimension between the outer molded body and the inner molded body.

  As the resin sheets 25 and 26 for forming the outer molded body, any thermoplastic resin used in the molding of the inner molded body 10 can be used. The material of the inner molded body 10 and the outer molded body may be the same or different, but considering the fixation by heat fusion, the same material is preferable. Also, the outer molded body may be a foam molded body formed by foaming a resin with a foaming agent, or may be a non-foamed body that is not foamed.

  Next, the molds 23 and 24 are moved forward toward the molten resin sheets 25 and 26. After the molds 23 and 24 are in contact with the molten resin sheets 25 and 26, air is sucked from a vacuum vent provided on the cavity surface of the molds 23 and 24, and as shown in FIG. Are closely attached to the cavity surfaces of the dies 23 and 24.

  After the molten resin sheets 25 and 26 are brought into close contact with the cavity surfaces of the molds 23 and 24 in this way, the resin sheets 25 and 26 are shaped into a shape along the surface of the cavity surfaces of the molds 23 and 24, and then FIG. As shown in FIG. 2, the inner molded body 10 previously molded between the molds 23 and 24 is inserted. Insertion of the inner molded body 10 is performed after the resin sheets 25 and 26 are shaped by the molds 23 and 24, so that a defect due to careless contact does not occur. Therefore, the distance (interval) between the inner molded body 10 and the shaped resin sheets 25 and 26 can be set arbitrarily, and the degree of freedom is high.

  After insertion of the inner molded body 10, as shown in FIG. 8, the molds 23 and 24 are advanced to perform mold clamping. When the molds are clamped, the pinch-off portions of the molds 23 and 24 abut against each other, so that the cavities 21 and 22 of the two molds 23 and 24 are closed, and the peripheral portions of the resin sheets 25 and 26 are welded together. Thereby, a parting line is formed in the joining surface of the two resin sheets 25 and 26, and the outer molded body 30 is formed.

  Further, by the mold clamping, the outer molded body 30 and the inner molded body 10 are integrated at the same time as the outer molded body 30 is molded. Specifically, when the peripheral portions of the resin sheets 25 and 26 constituting the outer molded body 30 are heat-sealed by clamping, the rib 11 of the inner molded body 10 is sandwiched between the resin sheets 25 and 26. Heat-sealed. As a result, the inner molded body 10 is shaped in-mold, and the inner molded body 10 is fixed and integrated inside the outer molded body 30 with a predetermined gap (intermediate air layer SP).

  In the mold clamping, it is possible to blow for finishing the molding of the resin sheets 25 and 26. By blowing air into the space between the inserted inner molded body 10 and the shaped resin sheets 25 and 26, the shape of the outer molded body 30 is finished to exactly match the shape of the cavities 21 and 22. be able to.

  FIG. 9 shows the form of the double-structured duct 40 produced through the above steps. As described above, in the molded double structure duct 40, the rib 11 of the inner molded body 10 is supported in the parting line of the outer molded body 30 while being sandwiched between the compression portions 31 of the outer molded body 30. The inner molded body 10 is disposed and fixed and integrated with the gap. Here, the state in which the inner molded body 10 is disposed with a predetermined gap refers to a state in which an intermediate air layer SP for heat insulation is formed between the inner molded body 10 and the outer molded body 30, and accordingly, the gap The size is about several mm to several cm.

  After the secondary molding, as shown in FIG. 10, post-processing such as cutting the end portion is required, but the post-processing step can be handled by a normal processing step. That is, the double-structured duct 40 after the secondary molding is molded in a form in which the opening is closed, but the cutting process of unnecessary portions, the finishing pressing process, etc. are performed in the inner molded body 10 and the outer molded body 30. Can be processed simultaneously, and the number of processes does not increase.

  Since the double-structured duct 40 molded as described above has an intermediate air layer between the outer molded body 30 and the inner molded body 10 without increasing the expansion ratio, the so-called deemed expansion ratio can be increased. It is possible to realize a duct having excellent heat insulation and high rigidity.

  In the molding method described above, since the outer molded body 30 is pre-shaped with the dies 23 and 24 and the inner molded body 10 is inserted between them, the parison contacts the inner molded body 10. There is no defect caused by. Therefore, it is possible to increase mass productivity. Further, when the outer molded body 30 is molded, it is not necessary to use an excessively large parison in order to avoid contact, and it is possible to mold with the resin sheets 25 and 26 having appropriate sizes. Therefore, it is possible to reduce the manufacturing cost. Furthermore, since the interval between the inner molded body and the outer molded body can be arbitrarily set when the inner molded body is inserted, the degree of freedom in design is high.

  In the above-described manufacturing method, primary molding (molding of the inner molded body 10) and secondary molding (molding of the outer molded body and in-mold in the inner molding) are performed as separate processes using separate molds. It is also possible to perform the process with a single mold.

FIG. 11 shows an example of a mold that performs primary molding and secondary molding simultaneously. The mold used is composed of two divided molds 51 and 52, and cavities 53 and 54 for molding the inner molded body and cavities 55 and 56 for molding the outer molded body are formed in parallel. ing. Corresponding to the cavities 53 and 54 and the cavities 55 and 56, molten resin sheets are supplied, respectively, and the inner molded body and the outer molded body are molded. Primary molding and secondary molding are usually performed in two shots. If the inner molding formed on the left side in the figure is inserted when molding the right outer molding in the figure, the operation is repeated. The molding of the inner molded body (primary molding) and the secondary molding (molding of the outer molded body and in-mold within the inner molding) can be performed in one shot.

  As mentioned above, although embodiment which applied this invention has been described, it cannot be overemphasized that this invention is not what is limited to the above-mentioned embodiment, In the range which does not deviate from the summary of this invention, a various change can be added. Is possible.

  For example, in the previous embodiment, the embodiment applied to the double structure duct has been described. However, the double structure is not limited to the duct but can be applied to various molded bodies. In that case, the shape etc. of the inner side molded object 10 and the outer side molded object 30 can be set arbitrarily, and the inner side molded object 10 may not be hollow depending on the case.

1, 2 Cavity 3, 4 Mold 5, 6 Resin sheet 10 Inner molded body 11 Rib 21, 22 Cavity 23, 24 Mold 25, 26 Resin sheet 30 Outer molded body 31 Compression section 40 Duplex structure duct 51, 52 Division Mold 53, 54 Cavity (for molding inner molded body)
55, 56 Cavity (for forming outer molded body)

Claims (5)

Each of the resin sheets is shaped by vacuum suction from the cavity surface of the mold,
While clamping the mold in a state where the pre-molded inner molded body is disposed between the pair of resin sheets, the pair of molded resin sheets are integrated to form an outer molded body, A method for producing a double structure, wherein the inner molded body is arranged with a predetermined gap inside the outer molded body.   When forming the inner molded body, a rib extending from the inner molded body is formed, and by integrating the rib with the outer molded body, the inner molded body is arranged with a predetermined gap inside the outer molded body. The method for producing a double structure according to claim 1, wherein the two structures are integrated. The rib is formed along a parting line of the inner molded body,
3. The method for producing a double structure according to claim 2, wherein when the mold is clamped, the rib is molded so as to be sandwiched between resin sheets for forming the outer molded body.   The inner molded body was formed by forming a pair of resin sheets by vacuum suction from the cavity surface of the mold, and then integrating the molded resin sheets by clamping the mold. The method for producing a double structure according to any one of claims 1 to 3, wherein the method is a product. The method for producing a double structure according to claim 4, wherein the molding of the inner molded body, the molding of the outer molded body, and the integration with the inner molded body are performed using the same mold.

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