JP4889119B2 - Molding method and molding apparatus for foamed resin molded product - Google Patents

Description

  The present invention relates to a molding method and a molding apparatus for a foamed resin molded article using a gas injection type injection molding method, and in particular, a foamed resin molding capable of maintaining good appearance performance by eliminating gas accumulation in a cavity. The present invention relates to a method for molding a product and a molding apparatus.

  FIG. 10 shows an automotive door trim 1 mounted on the indoor side of a door panel (not shown). The door trim 1 is lightweight, has excellent impact resistance, maintains desired rigidity, and is inexpensive. For this reason, a foamed resin molded product obtained by molding a foamed resin material obtained by adding a foaming agent to polypropylene resin into a required shape tends to be used. The door trim 1 has a center portion 1a at the center of the surface, and a groove portion 1b is formed at the periphery of the center portion 1a. Further, an armrest 1c that bulges indoors is formed in the inscribed portion 1a so that an occupant can rest on an elbow, and a mounting hole for attaching a switch panel and a pull handle (both not shown) to the armrest 1c. 1d has been established. Further, a door pocket opening 1e is formed on the lower side of the door trim 1, and a speaker grill 1f is provided on the front side of the door trim 1 as a single body or separately.

  A conventional molding method for molding the door trim 1 using this type of foamed resin molded product into a required shape will be described. First, as shown in FIGS. 11 and 12, a molding apparatus 2 used when molding the door trim 1 is roughly composed of a movable mold 3 and a fixed mold 4. More specifically, the movable die 3 is moved up and down by a predetermined stroke by driving the elevating cylinder 3a, and is clamped and opened with the fixed die 4 positioned below. A cavity C having a predetermined space is defined. On the other hand, the fixed-side mold 4 is provided with a manifold 4a and a gate 4b serving as a resin passage for the foamed resin material M supplied from an injection machine (not shown), and the foamed resin material M supplied from the injection machine is the manifold 4a. The cavity C is injected and filled through the gate 4b. Further, when the movable side mold 3 is lowered to the bottom dead center and is clamped with the fixed side mold 4, the movable side mold 3 and the fixed side mold are arranged by the seal member 5 disposed along the entire circumference. The sealing performance with the mold 4 is maintained well.

  In the conventional molding apparatus 2, a gas blow for increasing the internal pressure of the cavity C is performed before filling the foamed resin material M into the cavity C, while the gas in the cavity C is evacuated to the outside during the foaming reaction. A blow / vacuum mechanism 6 is provided. That is, the common pipe 6a facing the parting surface between the movable side mold 3 and the fixed side mold 4 is branched and connected to the blower 6c and the vacuum pump 6d via the switching valve 6b.

  Next, a conventional example of a foam molding method for the door trim 1 will be described. First, as shown in FIG. 13A, in a state where the movable side mold 3 and the fixed side mold 4 are clamped, gas is blown from the blower 6c of the blow / vacuum mechanism 6 into the cavity C through the common pipe 6a. The internal pressure of the cavity C is maintained at a high pressure. Thereafter, as shown in FIG. 13 (b), the foamed resin material M is injected and filled into the cavity C through an manifold (not shown) through the manifold 4a and the gate 4b. At this time, since the foamed resin material M has an increased internal pressure in the cavity C, the early foaming reaction is suppressed, and the foamed resin material M is quickly filled into the cavity C. Then, after the foamed resin material M is filled, as shown in FIG. 13C, the movable side mold 3 is retracted in the mold opening direction, and the switching valve 6b of the blow / vacuum mechanism 6 is switched to vacuum. The pump 6d is operated to discharge the gas in the cavity C to the outside, and the foaming reaction is performed in a state where the internal pressure of the cavity C is reduced. This method is called a counter pressure method, and a method for molding a foamed resin molded product and a molding apparatus using this method are described in detail in Patent Document 1.

Japanese Patent Publication No. 51-27266

  As described above, in the conventional method of forming the door trim 1 using the counter pressure method, when the excess gas in the cavity C is removed to the outside by the blow / vacuum mechanism 6 during the foaming step shown in FIG. In addition, due to the lack of space in the vertical wall due to the modeling of the inscribed portion 1a, excess gas cannot be completely removed, and as shown in FIG. 14, the gas remains particularly on the product surface of the inscribed portion 1a. Thus, it has been pointed out that the product surface has minute irregularities (commonly called “jud skin”) a, leading to poor appearance. This is particularly noticeable when the inscribed portion 1a of the island structure separated from the outer periphery is set at the center of the door trim 1. Moreover, it is not restricted to the inscribed part 1a, and the above-described yuzu skin a tends to occur in a place where gas tends to remain in the cavity C due to its shape.

  The present invention has been made in view of such circumstances, and is a molding method and a molding apparatus for a foamed resin molded article using a counter pressure method, and excess gas is contained in the cavity during the foaming reaction of the foamed resin material. To provide a molding method and a molding apparatus for a foamed resin molded product capable of mass production of a foamed resin molded product having a good foaming reaction by being reliably vented to the outside without stagnation. It is an object.

  In order to achieve the above object, the present inventors have used a counter-pressure method to accurately form a lightweight and rigid foamed resin molded article with high accuracy in a molding method and molding apparatus, for example, an island structure in a door trim. Efficiently solves conventional problems by providing a dedicated vacuum mechanism locally for specific parts where excess gas tends to accumulate partially, such as the inscribed part, and excess gas cannot be removed by vacuum from the outer periphery. Focusing on what can be done, the present invention has been completed.

That is, the present invention forms a cavity by clamping a movable mold and a fixed mold, and injects gas into the cavity through a blow vacuum mechanism provided on the outer periphery of both molds. The foamed resin material is injected and filled in the cavity with the cavity internal pressure increased, and then the movable side mold is opened and the gas in the cavity is vented to the outside through the blow vacuum mechanism. This is a method for molding a foamed resin molded article that performs foam molding by promoting the foaming reaction by reducing the internal pressure of the mold, as in the middle part of the island structure surrounded by the middle groove part. In the method for molding a foamed resin molded product having a shape part in which the gas in the cavity tends to remain, the foamed resin molded product has a shape part in which the gas in the cavity in the mold tends to remain Mounting hole is established by straw cutter during clamping of the mold is set, provided the local dedicated vacuum mechanism Oshikiri structure of the mold corresponding to the mounting hole, injection filling of the foaming resin material is complete After that , both the blow vacuum mechanism and the local dedicated vacuum mechanism are evacuated, and the foam molding is performed in a state where the internal pressure of the cavity is constantly reduced when the foamed resin material is injected and filled.

  Further, the molding apparatus used in the method of the present invention is a molding apparatus for a foamed resin molded product using a gas injection type injection molding method, and this molding apparatus includes a movable side mold movable for a predetermined stroke, and a foamed resin material. The fixed-side mold connected to the supply mechanism and the outer periphery of both the molds are supplied with a gas for increasing the internal pressure of the cavity to a predetermined value before filling with the foamed resin material. Blow / vacuum mechanism provided on the outer periphery of the mold for venting the gas in the cavity to the outside, and the press-cut structure part in the shape part where the gas in the cavity of the mold tends to remain. It is characterized by comprising a local dedicated vacuum mechanism for venting the gas in the shape part to the outside.

  Here, the use of foamed resin molded products can be applied to all automotive interior parts such as door trim, rear parcel shelf, floor trim, trunk trim, luggage side trim, roof trim, rear side trim, etc. It is suitable for interior parts that have a portion where gas cannot be removed from the outer periphery, such as the inscribed portion, and where gas tends to accumulate. Furthermore, a foaming agent is mixed in the synthetic resin as a material for the foamed resin molded product, and usable synthetic resins include polyethylene resins, polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, A vinyl chloride resin, a polyamide resin, a polyacetal resin, a polycarbonate resin, an ionomer resin, an acrylonitrile / butadiene / styrene (ABS) resin, and the like may be appropriately selected. As a foaming agent to be added to a synthetic resin, Organic foaming agents such as azodicarbonamide or inorganic foaming agents such as sodium bicarbonate can be used.

  The method of the present invention comprises three steps, a gas pressurizing step, a foamed resin filling step, and a foaming resin foaming step, and in the gas pressurizing step, the movable side mold and the fixed side mold are clamped. In this way, gas is supplied from a blow / vacuum mechanism disposed on the outer periphery of both molds in the cavity defined by the above, and the internal pressure of the cavity is maintained at a high pressure. After that, the foamed resin material is filled into the cavity, but since the internal pressure of the cavity is increased by the gas supply, the foamed resin material is quickly filled in the cavity without foaming with the foaming reaction suppressed. Is done. When the filling of the foamed resin material is completed, a foaming reaction of the foamed resin is induced and a foamed resin molded product is molded. At this time, the movable side mold is opened and the excess gas is discharged to the outside. However, when the excess gas is discharged to the outside, the blow / vacuum mechanism provided on the outer periphery is evacuated. At the same time, surplus gas that tends to stay inside the cavity can be quickly evacuated to the outside by the vacuum mechanism dedicated to the local area provided in the press-cut structure portion of the mold corresponding to the inscribed portion of the island structure.

  Therefore, according to the method of the present invention, the gas in the cavity is likely to be partly accumulated, and the gas is retained in the cavity by providing a local dedicated vacuum mechanism for the part where the gas cannot be removed by vacuum from the outer periphery. By doing so, it is possible to provide a foamed resin molded article that does not hinder foaming, eliminates appearance defects such as crushed skin, and has improved appearance performance.

  As described above, the foamed resin molding method and molding apparatus according to the present invention is a foamed resin molded product molding method and molding apparatus adopting a counter pressure method, in which gas tends to accumulate in the cavity, and from the outer periphery. Because it is possible to reliably vent the gas during the foaming process by arranging a local vacuum mechanism for the specific part where excess gas cannot be removed by vacuum alone, it is lightweight and It has the effect that the appearance performance of the foamed resin molded product having excellent rigidity can be maintained well.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for molding a foamed resin molded article and a molding apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the gist of the present invention is as described in the scope of claims, and the contents of the embodiments described below are merely examples of the present invention.

  1 to 9 show an embodiment of the present invention. FIG. 1 is a front view showing a door trim molded by the method of the present invention, FIG. 2 is a sectional view showing the structure of the door trim, and FIG. FIG. 4 is an explanatory diagram showing a dedicated vacuum mechanism in the molding apparatus shown in FIG. 3, and FIGS. 5 to 9 are moldings of a door trim to which the method of the present invention is applied. It is explanatory drawing which shows each process in a method.

  1 and 2, the door trim 10 to which the method of the present invention is applied is attached to the interior surface side of a front door panel of a vehicle (not shown) via a fixing means such as a clip (not shown), and is lightweight and has a desired rigidity. It is comprised from the foamed resin molded product provided with. Further, an inscribed portion 11 of an island structure is set at the center portion of the product surface, and an inscribed groove portion 12 is formed in a loop shape on the periphery of the inscribed portion 11. In addition, an armrest 13 that bulges indoors so that the occupant can rest on his / her elbow is set in the middle portion 11, and the armrest 13 includes an accessory such as a power window switch unit and a pull handle (not shown). A mounting hole 14 is provided for mounting. An attachment flange 15 for attaching a pocket cover (not shown) is set on the lower front side of the door trim 10.

  More specifically, the door trim 10 is configured by laminating skin layers 10b on the front and back sides of the foam layer 10a, and particularly adopts a counter pressure method that is lightweight and excellent in rigidity and can set the foaming ratio in a wide range. Has been. That is, there is a method of injecting gas into the cavity C when filling the foamed resin material to increase the internal pressure of the cavity C, and venting the gas within the cavity C during the foaming reaction to lower the internal pressure of the cavity C. By being adopted, it is characterized in that an excellent appearance design can be obtained without being restricted by modeling and without causing irregularities in the appearance of the product. Therefore, as is clear from the comparison between FIG. 2 and FIG. 13, in the method of the present invention, a minute unevenness (indicated by symbol “a” in FIG. 13) that is usually called “skin skin” occurs on the product surface of the inscribed portion 11. And has an excellent appearance design. In the present embodiment, the inscribed portion 11 of the island structure surrounded by the inscribed groove portion 12 has a shape portion A in which gas in the cavity C tends to remain when degassing from the outer periphery during the foaming reaction. It is shown as a representative example.

Next, the overall configuration of the molding apparatus 20 used in the molding method of the door trim 10 shown in FIGS. 1 and 2 will be described with reference to FIGS. First, the molding apparatus 20 is used in a method for molding a foamed resin molded product employing a counter pressure method. Specifically, the molding device 20 increases the internal pressure of the movable side mold 30 and the fixed side mold 40 that can be clamped and opened with each other, and the cavity C during injection filling of the foamed resin material M, while foaming. A blow / vacuum mechanism 50 for use in blow and vacuum, respectively, to lower the internal pressure of the cavity C during the foaming reaction of the resin material M, and a shape portion where gas tends to remain, such as the inscribed portion 11 of the island structure It is comprised from the vacuum mechanism 60 only for the center part provided in the metal mold | die 30 corresponding to A locally. Note that the gas used in the blow / vacuum mechanism 50 can be N ₂ gas, CO ₂ gas, factory air, or the like.

  More specifically, the movable side mold 30 can be moved up and down by a predetermined stroke by the elevating cylinder 31, and the mold surface of the movable side mold 30 is set to have a curved surface shape corresponding to the product shape of the door trim 10. A projection 32 is provided in a loop shape so as to correspond to the contact groove 12, and a recess 33 is formed in a portion corresponding to the armrest 13. On the other hand, the fixed mold 40 is provided with a manifold 41 and a gate 42 as a resin passage for the foamed resin material M supplied from an unillustrated injection machine. Further, a concave groove 43 is formed corresponding to the portion corresponding to the intermediate groove portion 12, that is, the protrusion 32, and a convex portion 44 is provided in a portion corresponding to the armrest 13.

  The movable mold 30 and the fixed mold 40 are set to have a narrow clearance because the movable mold 30 is lowered to the bottom dead center when the foamed resin material M is injected and filled. Thus, injection filling of the foamed resin material M is performed in a state where the internal pressure of the cavity C is increased and the foaming reaction is suppressed. Further, after the injection filling of the foamed resin material M into the cavity C is completed, in order to reduce the internal pressure of the cavity C, excess gas in the cavity C is vented to the outside, and the movable mold 30 is made minute. Perform stroke opening operation. As the blow / vacuum mechanism 50 for increasing the internal pressure of the cavity C when the foamed resin material M is injected and filled, first, an outer peripheral seal member 51 is disposed along the parting surfaces of the movable mold 30 and the fixed mold 40. The common pipe 52 is connected to the outside at the four corners of the fixed mold 40, and a switching valve 53 is provided in the common pipe 52, and is connected to the blower 54 and the vacuum pump 55 in a branched manner. . Therefore, by operating the switching valve 53, it is possible to increase the internal pressure of the cavity C by supplying gas from the blower 54 into the cavity C, and also, by operating the switching valve 53, By exhausting excess gas to the outside, the internal pressure of the cavity C can be controlled to be low.

  Furthermore, the method of the present invention is characterized in that a vacuum mechanism 60 dedicated to the inscribed portion is provided in a mold portion corresponding to the shape portion A where surplus gas is likely to remain, such as the inscribed portion 11 of the island structure. For this purpose, as shown in FIGS. 3 and 4, the mounting hole 14 of the armrest 13 is opened by the mold pressing structure simultaneously with the mold clamping of the movable mold 30 and the fixed mold 40. A vacuum mechanism 60 exclusively for the centering portion is disposed on the movable die 30 side in the press-cut structure portion B.

  Then, the vacuum mechanism 60 exclusively for the inscribed portion is actuated at the time of foaming of the foamed resin material M, so that the surplus gas corresponding to the inscribed portion 11 of the island structure easily remains in the cavity C including the shape portion A. The surplus gas can be surely vented from all of the parts, and it is possible to form the door trim 10 that has no appearance defect such as a crushed skin a and has a beautiful appearance performance.

  Hereafter, each process of this invention method is demonstrated based on FIG. 5 thru | or FIG. First, as shown in FIG. 5, in the initial stage of molding the door trim 10, first, the movable mold 30 is lowered by a predetermined stroke by driving the elevating cylinder 31, and the movable mold 30 and the fixed mold 40 are Is clamped. At this time, the foamed resin material M has not yet been supplied into the cavity C, and the blow / vacuum mechanism 50 has the gas sent from the blower 54 into the cavity C through the common pipe 52, and the internal pressure of the cavity C is set to a high pressure. Has been.

  Next, as shown in FIG. 6, the foamed resin material M is injected and filled into the cavity C through the manifold 41 and the gate 42 from the injection machine. However, since the internal pressure of the cavity C is controlled to be high, the foamed resin material M is It quickly penetrates into the cavity C with the foaming reaction suppressed.

  After that, as shown in FIG. 7, the movable die 30 is opened in the mold opening direction by driving the elevating cylinder 31, and the switching valve 53 of the blow / vacuum mechanism 50 is operated to Excess gas outside the contact portion 11 is evacuated to the outside, and the portion corresponding to the contact portion 11 is driven by a vacuum mechanism 60 dedicated to the contact portion as shown in FIG. Excess gas in the portion corresponding to the portion 11 is completely evacuated to the outside, and as shown in FIG. 9, the foamed resin material M is foamed and the door trim 10 made of a laminate of the foam layer 10a and the skin layer 10b is externally seen. Molding can be performed while maintaining good performance.

  As described above, when the method of the present invention is adopted, the counter pressure method is assumed. Therefore, when the foamed resin material M is injected and filled, the internal pressure of the cavity C is high, and the foamed resin material M is injected while suppressing the foaming reaction. After that, the movable mold 30 is opened in the mold opening direction, and the excess gas is evacuated to the outside by the vacuum action of the blow / vacuum mechanism 50 provided on the outer periphery. The internal pressure is controlled to be low, and foam molding of the foamed resin material M is performed smoothly. In particular, the mold 30 corresponding to the shape portion A where surplus gas tends to remain, such as the inscribed portion 11 of the island structure, Cavity at the time of the foaming reaction of the foamed resin material M by effectively using the press-cutting structure part B set to 40 and setting the vacuum mechanism 60 exclusively for the middle part in this part The pressure can be appropriately controlled, there is an effect that conventional uneven defect can be maintained easily Chuse' portion 11 like appearance performance of beautifully occur.

  Although the embodiment described above is applied to the molding method of the door trim 10, the application is not limited to this, and it can be applied to general foamed resin molded products using a gas injection type injection molding method.

  Further, as a dedicated vacuum mechanism provided in a specific part where excess gas tends to stay in the cavity C, as in the embodiment, the vacuum mechanism 60 is not limited to the incline portion dedicated vacuum mechanism 60, and an area having a groove portion of a general part, The present invention can be applied to a portion where excess gas is likely to remain, such as a speaker grill.

It is a front view which shows the door trim shape | molded by the method of this invention. It is the II-II sectional view taken on the line in FIG. It is sectional drawing which shows the whole structure of one Example of the shaping | molding apparatus of the foamed resin molded product which concerns on this invention. It is explanatory drawing which shows the vacuum mechanism for exclusive use in the shaping | molding apparatus shown in FIG. It is explanatory drawing which shows the gas pressurization process in the cavity in the molding method of the door trim shown in FIG. It is explanatory drawing which shows the injection filling process of the foamed resin material in the molding method of the door trim shown in FIG. It is explanatory drawing which shows the cavity back process in the molding method of the door trim shown in FIG. It is explanatory drawing which shows the venting process of the surplus gas in the molding method of the door trim shown in FIG. It is explanatory drawing which shows the foam molding process of the foamed resin material in the molding method of the door trim shown in FIG. It is a front view which shows the prior art example of the door trim which is an example of the foamed resin molded product shape | molded using the conventional counter pressure construction method. It is explanatory drawing which shows the whole structure of the shaping | molding apparatus which shape | molds the conventional door trim. It is a top view of the stationary side metal mold | die in the conventional door trim shaping | molding apparatus. It is process explanatory drawing in the shaping | molding method of the conventional door trim. It is sectional drawing which shows the malfunction point in the shaping | molding method of the conventional door trim.

Explanation of symbols

10 Door trim (foamed resin molded product)
DESCRIPTION OF SYMBOLS 10a Foaming layer 10b Skin layer 11 Centering part 12 Centering groove part 13 Armrest 14 Mounting hole 15 Pocket mounting flange 20 Molding apparatus 30 Movable side mold 31 Lifting cylinder 32 Projection 33 Concave part 40 Fixed side mold 41 Manifold 42 Gate 43 Concave groove 44 Convex part 50 Blow / vacuum mechanism 51 Peripheral seal member 52 Common piping 53 Switching valve 54 Blower 55 Vacuum pump 60 Dedicated vacuum mechanism for middle part M Foamed resin material A Shaped part where surplus gas tends to remain B Pressing structure C cavity

Claims (2)

A cavity (C) is formed by clamping the movable mold (30) and the fixed mold (40), and a blow and vacuum mechanism (50) provided on the outer periphery of both molds (30, 40). ) Through which gas is injected into the cavity (C), the foamed resin material (M) is injected and filled into the cavity (C) with the cavity internal pressure being increased, and then the movable mold (30) is dimensioned. While performing the opening operation, the gas in the cavity (C) is vented to the outside through the blow / vacuum mechanism (50), and the foaming reaction is promoted by reducing the internal pressure of the cavity (C) to perform foam molding. A method of molding a resin molded product (10), wherein a cavity (C) in a mold (30, 40) is formed like an inscribed portion (11) of an island structure surrounded by an inscribed groove portion (12). ) Shaped part where gas inside is likely to remain In the molding method of the resin foam product (10) having A),
In the foamed resin molded product (10), the gas (30, 40) in the mold (30, 40) is easily pressed when the mold (30, 40) is clamped in the shape part (A) where the gas (C) tends to remain. A mounting hole (14) opened by cutting is set, and a local vacuum mechanism (60) is provided in the press-cut structure part (B) of the mold (30, 40) corresponding to the mounting hole (14). After the injection filling of the foamed resin material (M) is completed, the blow / vacuum mechanism (50) and the local vacuum mechanism (60) are evacuated, and the cavity (C The foaming resin molded article molding method is characterized in that foam molding is performed in a state where the internal pressure is reduced to a certain level.   A molding apparatus (20) for a foamed resin molded article (10) using a gas injection type injection molding method, the molding apparatus (20) comprising a movable side mold (30) movable by a predetermined stroke, and a foamed resin material The fixed mold (40) connected to the supply mechanism of (M) and the inner pressure of the cavity (C) before the filling of the foamed resin material (M) are provided on the outer periphery of both molds (30, 40). A blow / vacuum mechanism (50) provided on the outer periphery of the mold (30, 40) for venting the gas in the cavity (C) to the outside during the foaming reaction And the press-cut structure part (B) in the shape part (A) in which the gas in the cavity (C) in the mold (30, 40) is likely to remain, and during the foaming reaction, It consists of a local vacuum mechanism (60) that vents gas to the outside. Foamed resin molded article of the molding apparatus, characterized in that.

Images