JPWO2017168566A1 - Molding method of resin foam with skin - Google Patents

Abstract

  It is formed between the first mold 1 and the second mold 2 for the purpose of reducing the amount of sag formed in the female hole of the resin foam and improving the appearance of the skin. The core material 3 is molded in the cavity, and the skin 4 is integrated with the surface 3 a of the core material 3. The second mold 2 can advance and retreat with respect to the first mold 2. A male pin 21 for forming a female hole 31 in the core material 3 protrudes from the second mold 2. Hole sagging of the foamed resin material 5 generated on the distal end side of the male pin 21 when the second mold 2 is retracted by a predetermined amount to the cavity surface 1a of the first mold 1 facing the distal end of the male pin 21. A recess 10 commensurate with e is formed.

Description

  The present invention relates to a molding method in which a skin is vacuum-formed on an injection-molded resin foam, and more particularly to a method for molding a resin foam with a skin in which female holes are formed in the resin foam.

  Conventionally, as described in, for example, Patent Document 1, there is a foamed product in which the surface of a resin foam formed by injecting a foamed resin material into a mold is covered with a skin. In this way, by covering and covering the surface of the resin foam with the skin, the appearance and overall strength can be improved.

  By the way, in integrating the skin on the surface of the resin foam in this way, in Patent Document 1, the foamed resin material is injected in a state where the skin is placed in the mold in advance, and then the foamed resin material is foamed to form the skin. It is designed to be integrated with.

  However, conversely, after filling the foamed resin material in the cavity between two opposed molds, one mold is retracted to provide a foaming space, and then the filled foamed resin By disposing the skin on the surface side of the material and performing vacuum molding, the foamed resin material can be integrated with the skin while foaming.

  At this time, when a female hole is formed in the resin foam, a male pin is provided in advance in one mold, and the female hole can be formed by die cutting of the male pin. Thus, in the resin foam in which the female hole is formed, the epidermis covers the surface of the resin foam so as to close the female hole.

JP 7-156182 A

  However, in the case of the latter molding method, first, after filling the foamed resin material into the initial cavity, one mold is retracted by a predetermined amount in order to provide a foaming space. As the mold moves backward, the male pin also moves backward, and a predetermined amount of the male pin is removed from the foamed resin material before foaming.

  However, in the foamed resin material in the thermoplastic state, the temperature of the portion in contact with the male pin, that is, the inner periphery of the female hole to be molded is lowered, and the skin layer is easily formed. Then, as shown in FIG. 5, when one mold a retreats, the friction between the outer periphery of the male pin b and the inner periphery of the female hole c increases, and the female hole b is located on the other mold d side. At the leading end, a hole sag e indicated by a broken line in the figure is generated. At this time, as shown in FIG. 6, the hole sag e becomes a funnel shape having a sag range A0 and a hole sag amount D0.

  Therefore, as shown in FIG. 7, the foamed resin material f is foamed in a state where the sag e is generated in the molded portion of the female hole c, and is formed on the surface h of the foamed resin foam g. The epidermis i will be adhered. For this reason, in the female hole c portion, a recess j is generated in the skin h due to the hole sag e, which causes a problem that the appearance is deteriorated. In the figure, k is a skin layer formed on the outer surface of the resin foam g.

  Therefore, the present invention has been made in view of such conventional problems, and it is possible to reduce the amount of sag formed in the female holes of the resin foam, and to improve the appearance of the skin. It aims at providing the molding method of a foam.

  In order to achieve this object, a method for molding a resin foam with a skin according to the present invention includes a first mold and a second mold that is capable of moving back and forth with respect to the first mold and has a male pin protruding therefrom. A first step of injecting and filling a foamed resin material into an initial cavity between the first mold and the second mold, and a second mold after filling the foamed resin material A second step of retreating the mold together with the male pin by a predetermined amount to provide a foaming space; and after forming the foaming space, a skin is disposed so as to cover the surface of the foamed resin material, and vacuum molding is performed in the foaming space. And a third step of forming a resin foam by foaming a foamed resin material, and a cavity surface of the first mold facing the tip of the male pin is arranged in the second step. Generated on the tip side of the male pin when the die 2 is retracted by a predetermined amount. Wherein the previously formed recesses matching the hole sagging amount of the resin material.

In this case, the recess is formed in a substantially trapezoidal cross section by a flat bottom surface larger than the tip end area of the male pin and an inclined surface that opens from the periphery of the bottom surface and opens to the cavity surface. It is preferable to apply a texture pattern to the inclined surface.

  According to the method for molding a resin foam with a skin according to the present invention, foaming is generated on the front end side of the male pin on the cavity surface of the first mold facing the front end of the male pin provided in the second mold. A concave portion corresponding to the sag of the resin material is formed. Thus, when the foamed resin material is filled in the initial cavity in the first step, the foamed resin material also enters the recess of the first mold, and the tip end side of the female hole to be molded is a hole. The foamed resin material has a protruding shape by the amount of sag. Therefore, when the male pin is retracted with the retraction of the second mold in order to provide the foaming space in the second step, the hole sag generated at the tip of the female hole molding portion of the foamed resin material is recessed. It can be filled with the protruding part of the foamed resin material that has entered. Thereby, the circumference | surroundings of the front end side of a female hole are planarized, and a hole droop can be reduced. Therefore, even when the foamed resin material is foamed by the third step in this state and the surface of the resin foam is covered and the skin is integrated, the skin is reduced from being depressed at the female hole portion. Since the flatness can be maintained, the appearance can be improved.

  In addition, since the textured surface of the concave portion having a substantially trapezoidal cross section is provided with a textured pattern, a slight uneven part of the textured pattern is formed on the peripheral edge of the female hole of the resin foam. Thereby, it becomes easy to remove the air remaining between the resin foam and the skin, and the adhesiveness of the skin is improved around the female hole, and as a result, the appearance can be further improved.

FIG. 1 is a cross-sectional view schematically showing a first step of the molding method of the present invention. FIG. 2 is a cross-sectional view schematically showing a second step of the molding method of the present invention. FIG. 3 is a cross-sectional view schematically showing a molded product obtained by the molding method of the present invention. FIG. 4 is a cross-sectional view showing in detail the concave shape of the first mold used in the molding method of the present invention. FIG. 5 is a cross-sectional view schematically showing a state in which the second mold is retracted by a conventional molding method. 6 is an enlarged cross-sectional view of a portion A in FIG. FIG. 7 is a cross-sectional view schematically showing a molded product obtained by a conventional molding method.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings. In the method of molding a resin foam with a skin according to the present invention, the core material used in conventional vacuum molding is generally formed by injection molding, but the core material is formed of foamed resin due to demand for weight reduction or the like. Therefore, a molding method using the foamed resin as a core material is proposed.

  FIGS. 1-4 shows one Embodiment of the molding method of the resin foam with a skin concerning this invention, The molding method of this embodiment passes through the 1st-3rd process described below, and is 1st. A core material 3 as a resin foam is molded in a cavity formed between the mold 1 and the second mold 2, and the skin 4 is integrated with the surface 3 a of the core material 3. It has become. The second mold 2 can be moved forward and backward (moved up and down in the figure) with respect to the first mold 2.

  At this time, in the second mold 2, a male pin 21 for forming a female hole 31 (see FIG. 3) such as a mounting hole is provided in the core member 3 so as to project toward the first mold 1. Has been. The male pin 21 is formed in a gentle taper shape whose diameter is reduced on the tip side so that the die can be easily removed. For example, in this embodiment, the base end diameter of the male pin 21 is 3.0 mm and the tip diameter is 1 mm. .5φmm.

  FIG. 1 shows a first process, in which a first mold 1 and a second mold 2 are clamped to provide an initial cavity S1 between the two molds 1 and 2, and the inside of the initial cavity S1. The foamed resin material 5 in a thermoplastic state is injected and filled from an injection machine (not shown). The foamed resin material 5 is indicated by a satin portion in the figure.

  In this embodiment, the foamed resin material 5 is a polypropylene resin, but other than this, a polyethylene resin, a polystyrene resin, a polyethylene terephthalate resin, a polyvinyl alcohol resin, a vinyl chloride resin, a polyamide resin, a polyacetal. A thermoplastic resin such as a resin, a polycarbonate resin, an ionomer resin, or an acrylonitrile / butadiene / styrene (ABS) resin can be used.

  In addition, when the first mold 1 and the second mold 2 are in a positional relationship in which the initial cavity S1 is provided, the tip of the male pin 21 is a cavity in which the first mold 1 faces the cavity S1. It abuts on the surface 1a (in this case, the bottom surface 11 of the recess 10 described later).

  FIG. 2 shows the second step, and after filling the initial cavity S1 with the foamed resin material 5 (first step), the second mold 2 is retracted by a predetermined amount together with the male pin 21 (moved downward in the figure). The foaming space S2 is provided.

  Next, the third step is performed. This third step will be described with reference to FIG. 2 showing the second step. After providing the foaming space S2, the first mold 1 is provided. And the surface 4a of the foamed resin material 5 are arranged and vacuum-molded by disposing a skin 4 (see FIG. 3) having a predetermined thickness t1 formed in a separate process.

  By this vacuum forming, the foamed resin material 5 is foamed in the foaming space S2 to form the core material 3 (see FIG. 3) having a predetermined thickness t2, and the skin 4 covers the surface 3a of the core material 3. Integrated in a state. In the present embodiment, the skin 4 is formed in a sheet shape from polypropylene (or other thermoplastic resin may be used), and is subjected to vacuum forming in a heated state.

  In this case, the vacuum forming may be performed by evacuating from the second mold 2 serving as the male mold, or may be performed from the first mold 1 serving as the female mold. Also, the core material 3 of the present embodiment can be used.

  Then, the core material 3 in which the skin 4 is integrated by vacuum molding is removed from the first mold 1 and the second mold 2, thereby forming a molded product of the resin foam with the skin shown in FIG. 3. Can be obtained. As this molded product, for example, there is a trim that decorates the interior of the vehicle interior.

  In the present embodiment, the skin 4 has an original thickness of 0.9 mm, and is compressed to 0.5 mm by being pressed by vacuum forming, so that t1 = 0.5 mm. On the other hand, the core material 3 has a thickness t2 after foaming of 2.5 mm, and the total thickness t3 = t1 + t2 of the molded product is suppressed to 3 mm.

  Here, in this embodiment, as shown in detail in FIG. 4, the second mold 2 is placed on the cavity surface 1 a of the first mold 1 with the tip of the male pin 21 facing, by the second step. A concave portion 10 is formed which corresponds to the hole sag (see FIG. 5) of the foamed resin material 5 generated on the distal end side of the male pin 21 when the fixed amount is retracted.

  As shown in FIG. 4, the recess 10 has a flat bottom surface 11 larger than the tip end area A <b> 1 of the male pin 21, and an inclined surface 12 that opens from the periphery of the bottom surface 11 and opens to the cavity surface 1 a. It is formed in a trapezoidal shape. At the center of the bottom surface 11, an extremely shallow recess 11 a for fitting the tip of the male pin 21 is provided.

  At this time, in the recess 10, an expected depth D and an expected range A between the outer periphery of the tip of the male pin 21 and the outer periphery of the opening of the cavity surface 1 a of the recess 10 are set. Optimal values for these expected amounts D and A are determined by the initial plate thickness of the core material 3 and the retraction amount of the second mold 2.

  The expected depth D is set to be equal to or smaller than the combined size of the retraction amount (foaming amount) of the second mold 2 and the total thickness of the skin 4. That is, this dimension is the maximum value, and if it is more than that, the molded product and the mold interfere with each other during vacuum molding. The expected range A is set to 6 to 9 times as a measured value with respect to the foaming amount.

  Therefore, the expected depth D and the expected range A are, for example, when the filling thickness of the foamed resin material 5 (interval of S1) is 1.8 mm and the thickness after foaming (interval of S1 + S2) is 2.5 mm, that is, When the retraction amount of the second mold 2 is 0.7 mm, it is preferable to set D≈0.5 mm and A≈5.5 mm.

  In the present embodiment, the embossed pattern 13 is provided on the inclined surface 12 of the recess 10. In addition, this wrinkle pattern 13 may be attached over the cavity surface 1a of the recessed part 10 peripheral part. In addition, since the bottom face 11 of the recessed part 10 is a part in which the male pin 21 and the cavity surface 1a are in close contact, the embossed pattern is not attached.

  As described above, according to the molding method of the resin foam with skin of the present embodiment, the tip of the male pin 21 provided in the second mold 2 is opposed to the cavity surface 1a of the first mold 1 facing. By providing the recess 10, the foamed resin material 5 filled in the initial cavity S 1 enters the recess 10, and the foamed resin material 5 protrudes toward the tip of the female hole 31 to be molded. Yes.

  At this time, the recess 10 is formed so as to correspond to the hole sag e of the foamed resin material 5 generated on the distal end side of the male pin 21, so that it protrudes toward the distal end side of the female hole 31 to be molded. The amount of lift of the foamed resin material 5 is an amount commensurate with the amount of hole sag e.

  Therefore, when the male pin 21 is retracted as the second mold 2 is retracted in order to provide the foaming space S2 in the second step, the protruding portion of the foamed resin material 5 that has entered the recess 10 is the male pin 21. And then falls into the formation portion of the female hole 31. Thereby, the hole sagging e generated at the tip of the molded portion of the female hole 31 of the foamed resin material 5 can be filled with the protruding portion of the foamed resin material 5 that has entered the recess 10. The periphery can be flattened to reduce the hole sag e.

  In this state, even when the foamed resin material 5 is foamed by the third step and the skin 4 is integrated by covering the surface 3 a of the core material 3, the skin 4 is recessed at the female hole 31 portion. Therefore, the appearance can be improved.

  In addition, according to the present embodiment, since the embossed pattern 13 is attached to the inclined surface 12 of the recess 10 formed in a substantially trapezoidal cross section, the minute uneven portion of the embossed pattern 13 is the female hole 31 of the resin foam 5. It is formed at the periphery. Thereby, it becomes easy to remove the air remaining between the resin foam 5 and the skin 4, the adhesiveness of the skin 4 is improved around the female hole 31, and the appearance can be further improved.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to this, and various other embodiments can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 1st metal mold | die 1a Cavity surface of 1st metal mold | die 2 2nd metal mold | die 21 Male pin 3 Core material (resin foam)
3a Surface of core material 4 Skin 5 Foamed resin material 10 Recess 11 Recess bottom surface 12 Recessed inclined surface 13 Wrinkle pattern e Hole sag S1 Initial cavity S2 Foam space

Claims (2)

A first mold and a second mold that is capable of advancing and retreating with respect to the first mold and has a male pin protruding therefrom;
A first step of injecting and filling a foamed resin material into an initial cavity between the first mold and the second mold;
A second step of providing a foaming space by retracting the second mold together with the male pin by a predetermined amount after filling with the foamed resin material;
And a third step of forming a resin foam by foaming the foamed resin material in the foamed space by forming a skin so as to cover the surface of the foamed resin material after the foamed space is provided and vacuum forming. A method of molding a resin foam with a skin,
Hole sag of the foamed resin material generated on the tip side of the male pin when the second die is retracted by a predetermined amount in the second step to the cavity surface of the first die facing the tip of the male pin A method for forming a resin foam with a skin, characterized in that a recess corresponding to the above is formed.   The recess is formed in a substantially trapezoidal cross section by a flat bottom surface larger than the tip end area of the male pin and an inclined surface that opens from the periphery of the bottom surface and opens to the cavity surface. The molding method of the resin foam with a skin of Claim 1 characterized by the above-mentioned.

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