JP4743860B2 - Molding method and molding die for foamed resin molded product - Google Patents

Description

  The present invention relates to a molding method and a molding die for a foamed resin molded article employing a molding method in which a mold clearance is varied between an injection filling process and a foaming process of a foamed resin material, and in particular, an accurate corner portion in an opening. The present invention relates to a molding method and a molding die for a foamed resin molded product that can be shaped and have improved appearance performance in the vicinity of an opening and alignment accuracy with a counterpart component.

  FIG. 13 shows an automotive door trim 1 mounted on the indoor surface side of a door panel (not shown). This door trim 1 is lightweight, has excellent rigidity and impact resistance, and is inexpensive. Many foamed resin molded products such as polypropylene (PP) foam are used. The door trim 1 is integrally formed with an armrest portion 1a that bulges toward the indoor side. A door pocket opening 1b is formed below the armrest portion 1a, and a speaker grill 1c is provided on the front side of the door trim. 1 or a separate body.

  And the conventional molding method which shape | molds the door trim 1 using this kind of foamed resin molded product in a required shape is demonstrated based on FIG. 14, FIG. FIG. 14 shows a schematic configuration of the molding die, and FIG. 15 shows a time chart of the die. The molding die 2 is generally composed of a movable side die 3 and a fixed side die 4, and the movable side die 3 can be moved up and down by a predetermined stroke by driving the elevating cylinder 3 a. The mold is clamped. In addition, an injection machine (not shown) is connected to the stationary mold 4, and a foamed resin material M supplied from the injection machine is injected and filled into the cavity C between the molds 3 and 4.

  Here, in the initial mold state at the time of mold clamping, the mold position of the movable side mold 3 is the position (a1) in the time chart of FIG. 15, and in this state, the foaming resin material M is transferred from the injection machine. Is injected and filled in a cavity C defined between the movable mold 3 and the fixed mold 4. Then, after a certain period of time, the movable mold 3 is moved in the mold opening direction, and the mold is opened to the position (a2) in the time chart of FIG. The door trim 1 is molded. That is, at the position (a1) of the mold, the clearance between the movable side mold 3 and the fixed side mold 4 is set to be small, so that the foaming reaction of the foamed resin material M is suppressed in the cavity C. The foamed resin material M can be filled quickly. In the filled foamed resin material M, a solid skin layer is immediately formed at a portion in contact with the mold surface of the movable side mold 3 or the fixed side mold 4, but the inside remains in an unfoamed state. .

  If the mold is opened to the position (a2), that is, by setting the mold clearance between the movable mold 3 and the fixed mold 4 slightly wide, a foaming space can be secured. The foamed resin molded product (door trim) 1 can be molded into a final product shape by smoothly performing the foaming reaction of the foamed resin material inside the skin layer (see Patent Document 1 as a similar technique).

JP 2002-120252 A

  As described above, in the conventional molding method of the foamed resin molded product (door trim) 1, the mold clearance between the movable mold 3 and the fixed mold 4 is adjusted to perform accurate molding. Yes. That is, the foam clearance can be secured by setting the mold clearance relatively small and setting the mold clearance relatively large during the foaming reaction while the foamed resin material M can be quickly supplied into the mold with foaming suppressed. Thus, the door trim 1 can be accurately formed into the final product shape.

  Here, the molding situation in the terminal corner part of the door trim 1 is demonstrated based on FIG. FIG. 16A shows a state immediately after mold clamping before injection filling of the foamed resin material M, and FIG. 16B shows an injection filling process in which the foamed resin material M is injected and filled into the cavity C. It is shown. In the foamed resin material M injected and filled into the cavity C, the skin layer a is formed on the outer surface of the foamed resin material M at the portion in contact with the mold surface. Next, as shown in FIG. 16 (c), the movable mold 3 is retracted to secure a foaming space, and as shown in FIG. 16 (d), the foamed resin material inside the skin layer a is enclosed. M foams to form the foam layer b, and a predetermined plate thickness is secured.

  However, after the skin layer a is formed, when the movable mold 3 is retracted, a gap is generated between the skin layer a and the mold surface of the movable mold 3, and the normal general surface is foamed inside. It is possible to increase the plate thickness of the product by the foaming pressure of the resin material M and ensure the rigidity. However, since the skin layer a suppresses the foaming reaction at the terminal portion, the molded product is the movable side mold 3. In particular, it becomes impossible to follow the mold surface corner portion 3b. Therefore, although a sharp corner line is preferable, as shown in FIG. 16 (d), it can be molded only in a rounded shape, and the appearance performance is deteriorated, and the alignment accuracy with adjacent parts is improved. The problem of lowering has been pointed out.

  The present invention has been made in view of such circumstances, and is a mold that includes a movable mold that can be clamped and opened with each other, a fixed mold, and an injection machine that supplies a foamed resin material. In particular, the present invention relates to a molding method and a molding die for a foamed resin molded product in which the mold clearance is variable between the injection filling process and the foaming process of the foamed resin material. An object of the present invention is to provide a molding method and a molding die for a foamed resin molded product that can accurately shape the shape at the corner of the opening, and can improve the appearance performance in the vicinity of the opening and the alignment accuracy with the counterpart part. And

  In order to solve the above-mentioned problems, the present invention, after clamping the movable side mold and the fixed side mold, injection-filled the foamed resin material into the cavity between the two molds, and then the movable side mold Retract in the mold opening direction to secure foaming space, foam the unfoamed half-molded product to mold the foamed resin molded product, and mold the foamed resin molded product with the opening partly opened In the method, in order to form an opening in the foamed resin molded product, a protrusion is formed to protrude toward the fixed mold side at a corresponding portion of the movable mold, and a frictional resistance is provided on the outer peripheral surface of the protrusion. By setting the minute unevenness to be increased, when the movable mold is retracted, the corner portion of the non-foamed half-molded product is fixedly held by the minute unevenness portion of this protrusion, and the R drooping at the corner portion It is characterized by avoiding.

  Furthermore, a molding die used in the method of the present invention is composed of a movable side die, a fixed side die, and an injection machine that is connected to the fixed side die and supplies a foamed resin material. The mold and the fixed mold are clamped, and the foamed resin material is injected and filled into the cavity between the molds from the injection machine, and then the movable mold is retracted to secure the foaming space and unfoamed In the molding mold of the foamed resin molded product for molding the foamed resin molded product, the foaming reaction of the half-molded product in the state corresponds to the opening of the foamed resin molded product. Thus, a protrusion extending toward the fixed mold side is formed to project, and the outer peripheral surface of this protrusion follows the retreating operation of the movable mold to hold the corner portion of the semi-molded product. It is characterized in that a minute uneven portion is provided.

  Here, the movable side mold in the molding die can be moved for a predetermined stroke by a cylinder or a press ram so that the mold can be clamped and opened with respect to the fixed side mold. A first mold position that secures a narrow mold clearance between the fixed mold and the movable mold in the process, and a second mold that secures a foaming space by retreating from the first mold position by a predetermined stroke. The stroke of the movable mold is controlled to include the position.

  On the other hand, the fixed-side mold is provided with resin passages such as a hot runner and a valve gate in order to supply the foamed resin material into the cavity from a continuous injection machine. And, in order to form an opening in the foamed resin molded product, a protrusion facing the fixed mold side is provided on the movable side mold, and the shape of this protrusion is the shape of the opening formed in the foamed resin molded product. And are set according to the dimensions. And, on the outer surface of this projection, a micro uneven part such as a drawing pattern is formed, and in this way, in the foam molding process in which the movable side mold retreats to secure a foaming space, The corner part is held in engagement by frictional resistance with the minute uneven part formed on the outer peripheral surface of the projection, and the corner part of the semi-molded product is moved to the movable side mold side following the backward movement of the movable side mold. R dripping can be avoided.

  Therefore, according to the method of the present invention, the foamed resin material is injected and filled into the cavity by setting minute irregularities such as a drawing pattern on the outer surface of the projection of the fixed mold in the molding die. After that, in order to secure the foaming space, when the movable side mold retreats for a certain stroke, the opening edge corner portion of the semi-molded product follows the outer peripheral surface of the projection, and conventionally R dripping has occurred. Accurate shape formation can be performed in the portion that has been.

  As described above, according to the method for molding a foamed resin molded product according to the present invention, a molding method for molding a foamed resin molded product by changing the mold clearance during injection filling and the mold clearance during the foaming reaction, In particular, since a minute uneven portion is set on the outer peripheral surface of the protrusion provided on the movable mold, an opening is formed in the foamed resin molded product by this protrusion, and when the movable mold is retracted, the foam is in an unfoamed state. Since the opening edge corner part of the semi-molded product is made to follow the protrusion of the movable mold, the shape of the opening edge corner part can be accurately formed, the appearance performance can be improved, and the other parts The effect is that the alignment accuracy can be increased.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a method for molding a foamed resin molded product and a mold according to the present invention will be described in detail 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.

  FIGS. 1 to 12 show an embodiment of the present invention. FIG. 1 is a front view showing a door trim having an upper and lower split structure in which a foamed resin molded product according to the present invention is applied to a door trim lower, and FIG. 3 and 4 are cross-sectional views of the main parts showing the boss holes and screw holes of the door trim lower in the door trim, and FIG. 5 is a molding die used for molding the door trim lower in the door trim. FIG. 6 is a side view and an external view showing a protrusion for forming a hole of a foamed resin molded product in the molding die, and FIG. 7 is a movable side die in the molding die shown in FIG. FIG. 8 to FIG. 12 are explanatory views showing the molding process of the door trim lower.

  In FIG. 1 and FIG. 2, the automobile door trim 10 is composed of an upper and lower divided body of a door trim upper 20 and a door trim lower 30. An inside handle escutcheon 11 is attached to the door trim upper 20, and a pull handle 12 and a power window switch finisher 13 are attached to an armrest portion on which an occupant places an elbow. On the other hand, the door trim lower 30 is provided with a door pocket opening 14 capable of accommodating equipment, and a speaker grill 15 is provided integrally or separately on the front side thereof. A pocket back cover 16 is attached to the back side of the door pocket opening 14.

  Further, as shown in FIG. 2, the door trim upper 20 and the door trim lower 30 are configured by a laminated structure in which a skin 22 is pasted on the surface of a resin core 21, as shown in FIG. 2. Synthetic resins used as the material of the resin core material 21 include polyethylene resins, polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, vinyl chloride resins, polyamide resins, polyacetal resins, polycarbonate resins. A resin, an ionomer resin, an acrylonitrile / butadiene / styrene (ABS) resin, or the like may be selected as appropriate, and a filler such as talc, clay, or wood powder may be mixed into the synthetic resin as desired. On the other hand, the skin 22 is made of a synthetic resin sheet such as a thermoplastic elastomer resin represented by TPO (thermoplastic olefin), or a synthetic resin sheet such as a laminated sheet material lined with a cushion layer such as polyethylene foam on the back side of the TPO sheet. it can.

  Further, in order to mold the door trim upper 20 into a desired shape, the injection molding method and the mold press molding method are suitable in consideration of mass productivity. That is, the outer skin 22 is set in a molding die, and the resin core material 21 is molded into a desired curved shape by injection filling the molten resin after the mold clamping or immediately before the mold clamping. The skin 22 can be integrally attached to the surface side. On the other hand, the door trim lower 30 uses a foamed resin molded product in the present invention, and a foaming agent is mixed in the synthetic resin. For example, usable synthetic resins include polyethylene resins, polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, vinyl chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, and ionomer resins. The resin is suitably selected from acrylonitrile / butadiene / styrene (ABS) resin and the like. The synthetic resin is mixed with an organic foaming agent such as azodicarbonamide or an inorganic foaming agent such as sodium bicarbonate.

  The door trim 10 shown in FIG. 1 and FIG. 2 has a good product appearance due to the accent effect on the appearance of the door trim upper 20 and the door trim lower 30, and the molding die can be made compact. Constructing the door trim lower 30 from a foamed resin molded product contributes greatly to weight reduction. Note that the door trim upper 20 and the door trim lower 30 are joined to each other with mounting holes 23 formed in the door trim upper 20 at predetermined pitch intervals in the width direction, and the rear surface of the upper edge of the door trim lower 30 corresponding to the mounting holes 23. The mounting boss 31 protrudes toward the panel side, and the mounting boss 31 is inserted into the mounting hole 23, and then the end of the mounting boss 31 is subjected to caulking such as ultrasonic welding caulking or thermal caulking. By applying, the door trim upper 20 and the door trim lower 30 are integrated. Further, as shown in FIG. 3, the door trim lower 30 manufactured by the method of the present invention is crimped after the welding boss 16 a of the pocket back cover 16 is inserted into the boss hole 32 of the door trim lower 30. However, the shape of the corner portion 32a of the boss hole 32 is accurately formed, and there is no problem in position regulation or the like. Similarly, as shown in FIG. 4, in order to insert the screw 17, the corner portion 33a is accurately shaped with respect to the screw hole 33 provided in the door trim lower 30. The corner portion 33a Even if it is exposed to the outside as a design surface, no problem occurs.

  As described above, the door trim lower 30 manufactured by the method of the present invention has the shape of the corner portions 32a and 33a in the openings such as the boss hole 32 and the screw hole 33, etc., so that it can be accurately Are accurately performed and have the advantage of excellent appearance design.

  Next, a schematic configuration of a molding die used for molding the door trim lower 30 will be described with reference to FIG. The molding die 40 is generally composed of a movable die 50, a fixed die 60, and an injection machine 70. More specifically, the movable mold 50 is driven to take three positions of a foaming position in addition to a mold clamping position and a mold opening position by an operation of a drive cylinder (not shown). A press ram 51 for this purpose is connected to the movable mold 50. On the other hand, in the fixed side mold 60, the molten resin is supplied to the mold surface through the hot runner 61 and the valve gate 62 which are resin passages of the molten resin supplied from the injection machine 70, and the molded resin molded product is molded. An ejector pin 63 for projecting is provided.

  Further, the door trim lower 30 is formed into a required shape along the cavity C shape defined between the movable side mold 50 and the fixed side mold 60, but the boss hole 32 opened in the door trim lower 30. In order to form the screw hole 33, as shown in FIG. 6, a protrusion 52 that matches the shape and dimensions of the boss hole 32 and the screw hole 33 is provided at a predetermined position on the movable die 50. Is formed. In addition, a shallow concave portion 64 for receiving the tip of the protrusion 52 of the movable mold 50 is formed on the mold surface of the fixed mold 60. A feature of the method of the present invention is that a minute uneven portion 53 such as a drawing pattern is set on the outer peripheral surface of the protrusion 52. The effect of the minute uneven portion 53 will be described later.

  7 shows a time chart of the movable mold 50 in the molding die 40, and FIGS. 8 to 12 show the molding process of the door trim lower 30 using the molding die 40 over time. That is, the movable mold 50 is moved from the mold opening position (the point shown in FIG. 7A by the time chart) by the operation of the drive cylinder, and the bottom dead center (time of FIG. 7). The movable side mold 50 is clamped to a point where a certain clearance is maintained with respect to the fixed side mold 60.

  Then, after the movable side mold 50 is clamped with respect to the fixed side mold 60, the foamed resin material M is injected and filled into the cavity C from the injection machine 70 through the hot runner 61 and the valve gate 62 as shown in FIG. . At this time, although not shown, it is also possible to adopt a counter pressure method in which air is forcibly introduced from the outside into the cavity C and the resin is filled in the cavity C so that the foamed resin material M does not undergo a foaming reaction. Next, when the injection filling process of the foamed resin material M is completed, the movable mold 50 is retracted in the mold opening direction as shown in (c) to (d) of the time chart of FIG. In the backward movement of the movable mold 50, as shown in FIG. 9, the size of the backward stroke is set so that the clearance of the general part is 3.6 mm. At this time, an unfoamed half-molded product P is accommodated in the cavity C, and a foaming space S corresponding to the retreat stroke of the movable mold 50 is secured.

  As shown in FIG. 10, the openings such as the boss holes 32 and the screw holes 33 formed in the door trim lower 30 have minute uneven portions 53 on the outer peripheral surface of the protrusion 52. Due to the frictional resistance between the portion 53 and the opening edge of the door trim lower 30, in particular, the corner portions 32a and 33a of the boss hole 32 and the screw hole 33 are fixedly held on the outer peripheral surface of the projection 52, and the movable side mold It will shift to 50 backward directions. Thereafter, as shown in FIG. 11, the foamed reaction is induced in the unfoamed half-molded product P, and the door trim lower 30 is molded to have a desired thickness in a space having a large clearance. At this time, as shown in FIG. 12, the opening edge portions such as the boss hole 32 and the screw hole 33 are formed with high accuracy without causing R sagging.

  As described above, according to the method of the present invention, the movable side mold 50 is provided with the protrusion 52 having a size and shape corresponding to the boss hole 32 and the screw hole 33 of the door trim lower 30, and the outer periphery of the protrusion 52. The shape of the boss holes 32 and the corners 32a and 33a of the screw holes 33 in the door trim lower 30 can be accurately determined, and the appearance performance can be achieved with the simple structure of forming the minute irregularities 53 such as a drawing pattern on the surface. In addition, it has an exceptional effect that it can improve the alignment accuracy with the mating part.

  In the embodiment described above, the method of the present invention is applied to the method of manufacturing the door trim lower 30 in the upper and lower split type door trim 10. However, the application of the method of the present invention is not limited to this, and foamed resin molding The method of the present invention can be applied to all products. It is also possible to use a counter pressure method for supplying compressed air into the cavity when the foamed resin material M is injected and filled. Further, as the shape of the minute uneven portion 53 formed on the outer peripheral surface of the protrusion 52 of the movable-side mold 50, a screw groove, a latch groove or the like may be used in addition to the drawing pattern shown in the embodiment. Is not limited.

It is a front view which shows the door trim of the upper and lower split structure using the door trim lower produced by applying the foamed resin molded product which concerns on this invention. It is the II-II sectional view taken on the line in FIG. It is sectional drawing which shows the hole for bosses which inserts the welding boss | hub of the pocket back cover in the door trim lower shown in FIG. It is sectional drawing which shows the screw hole which penetrates the screw in the door trim lower shown in FIG. It is a schematic diagram which shows the structure of the shaping die used in order to shape | mold the door trim lower shown in FIG. It is (a) side view and (b) external view which show the protrusion set to the shaping die shown in FIG. It is a time chart figure of the shaping die in the molding method of the door trim lower shown in FIG. It is explanatory drawing which shows the filling process of the foamed resin material in the molding method of the door trim lower shown in FIG. It is explanatory drawing which shows the state at the time of backward movement of the movable side metal mold | die in the molding method of the door trim lower shown in FIG. FIG. 10 is an explanatory view showing a state in the vicinity of the boss hole when the movable mold shown in FIG. 9 is retracted. It is explanatory drawing which shows the foam molding process in the molding method of the door trim lower shown in FIG. It is sectional drawing which shows the structure of the hole part for boss | hubs in the foam molding process shown in FIG. It is a front view which shows the conventional door trim. It is a schematic diagram of the molding die used when shape | molding the conventional door trim. It is a time chart figure of the shaping die used when shape | molding the conventional door trim. It is explanatory drawing which shows the molding process of the product terminal in the conventional foamed resin molded product.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Automotive door trim 20 Door trim upper 30 Door trim lower 31 Mounting boss 32 Boss hole 33 Screw hole 40 Molding die 50 Movable side die 51 Press ram 52 Protrusion 53 Minute uneven part 60 Fixed side die 61 Hot runner 62 Valve gate 63 Ejector pin 70 Injection machine C Cavity M Foamed resin material P Semi-molded product S Foaming space

Claims (2)

After the movable side mold (50) and the fixed side mold (60) are clamped, the resin foam (M) is injected and filled into the cavity (C) between the two molds (50, 60), and then The movable mold (50) is retracted in the mold opening direction to secure the foaming space (S), and the foamed resin molded product (30) is molded by foaming the unfoamed semi-molded product (P). And in the molding method of the foamed resin molded product (30) formed by opening the opening (32) in part,
In order to form the opening (32) in the foamed resin molded product (30), a protrusion (52) is formed to project toward the fixed mold (60) at a corresponding portion of the movable mold (50). The projections (52) are provided with micro-concave portions (53) that increase the frictional resistance on the outer peripheral surface thereof, so that when the movable mold (50) is retracted, an unfoamed half-molded product ( A method of molding a foamed resin molded product, characterized in that the corner portion of P) is engaged and held by the minute uneven portion (53) of the protrusion (52) to avoid R sagging at the corner portion. The movable side mold (50), the fixed side mold (60), and the injection machine (70) that is connected to the fixed side mold (60) and supplies the foamed resin material (M). The side mold (50) and the fixed side mold (60) are clamped, and the foamed resin material (M) is injected from the injection machine (70) into the cavity (C) between the molds (50, 60). After that, the movable mold (50) is retracted to secure the foaming space (S), the foaming reaction of the unfoamed semi-molded product (P) is performed, and the foamed resin molded product (30) In the molding die (40) of the foamed resin molded product (30) for molding
The movable mold (50) in the mold (40) has a protrusion (52) extending toward the fixed mold (60) corresponding to the opening (32) of the foamed resin molded product (30). ) Is projected and formed on the outer peripheral surface of the projection (52) so as to follow the retreating operation of the movable mold (50) to hold the corner portion of the semi-molded product (P). A molding die for a foamed resin molded product, wherein an uneven portion (53) is provided.

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