JP6121274B2 - Foamed resin molded product and manufacturing method thereof - Google Patents

Description

  According to the present invention, the boss of the resin molded product is inserted into the mounting hole of the foamed resin molded product, and the tip of the inserted boss is fastened to the foamed resin molded product, thereby being attached and joined to the resin molded product. In particular, the present invention relates to a foamed resin molded product and a method for manufacturing the same, and in particular, aims to improve the size and position accuracy of the mounting hole.

  Conventionally, as shown in FIG. 4A, for example, a door trim DT known as an automobile interior part is manufactured by manufacturing a door trim lower DT1 as a foamed resin molded product 1, and separately forming a door trim upper DT2 by resin molding. While being manufactured as a product 2, the resin molded product 2 is attached and joined to the foamed resin molded product 1 (see FIGS. 5A and 5B).

  For example, as shown in FIGS. 4B and 4C, the resin-molded product 2 (door trim upper DT2) is attached to the foamed resin-molded product 1 (door trim lower DT1). The boss 4 of the resin molded product 2 is inserted into the mounting hole 3, and the tip of the inserted boss 4 is fastened to the foamed resin molded product 1 as shown in FIG. In FIG.5 (b), as an example of the fastening method, the front-end | tip part of the boss | hub 4 which protruded from the attachment hole 3 is fastened by the crimping process by heat melting.

  FIG. 6A is an enlarged view of a portion where the vicinity of the mounting hole is molded in a molding die when the foamed resin molded product having the mounting hole of FIG. 4 is manufactured by injection molding of a foamed resin material. FIG. 6B is a cross-sectional view of the mold, and FIG. 6B is a view showing an outline of the vicinity of the attachment hole made by the mold, and FIG. 6C is a cross-sectional view taken along line EE in FIG. It is an enlarged view.

  Referring to FIG. 6A, in the molding die 100, a movable mold 101 and a fixed die 102 form a cavity 103 having a required shape, and the inner surface of the movable mold 101 forming the cavity 103 is formed. 4 (b) includes a core 104 for forming the mounting hole 3 and a groove 105 for forming a rib RB at one opening end 3A edge of the mounting hole 3 (for example, (See Patent Document 1).

  6A, the step of injecting and filling the foamed resin material into the cavity 103 from an injection gate (not shown), and the movable mold 101 is retracted after the injection filling is completed. By securing a foaming space of the foamed resin material between the mold 101 and the fixed mold 102 and foaming the foamed resin material, the mounting hole 3 is provided as shown in FIG. The foamed resin molded product 1 is manufactured.

  However, in the foamed resin molded product 1 provided with the mounting hole 3 in FIG. 4B described above, the rib RB is provided only at the edge of one opening end 3A of the mounting hole 3, and thus will be described below. This causes a problem that the size and position accuracy of the mounting hole to be reduced is lowered.

<Deterioration of mounting hole dimensions and position accuracy>
When the foamed resin molded product 1 is manufactured with the molding die 100 of FIG. 6A, the size of the mounting hole 3 shown in FIG. ) And sagging (changes in the size and shape of the mounting hole 3 occurring in the depth direction of the mounting hole 3), and the size and position accuracy of the mounting hole 3 are lowered. The cause is considered as follows.

  In the molding die 100 shown in FIG. 6A, a rib made of an unfoamed resin material is provided at one opening end 3A edge of the mounting hole 3 when the movable die 101 is retracted when securing the foaming space. The RB has already been completed in a state of being engaged in the groove 105 of the movable mold 101. In this state, when the retracting operation of the movable mold 101 for securing the foaming space is performed, the rib RB is pulled in the retracting direction, and accordingly, the entire mounting hole 3 is pulled in the same direction.

  At this time, the entire periphery of the mounting hole 3 is cooled and solidified by contact with the core 104 and the movable mold 101, that is, the solid layer S made of an unfoamed resin material like the rib RB (FIG. 6C). ))), It is impossible to foam in any direction, and the vicinity of the other opening end 3B of the mounting hole 3 is not engaged anywhere, so the vicinity of the other opening end 3B of the mounting hole 3 It is considered that shape deformation such as lifting in the backward direction of the movable mold 101 occurs, and sagging and gaps as shown in FIG.

<< Problems associated with sagging and skies shown in FIG. 6 (c) >>
For example, as shown in FIG. 6 (c), the vicinity of the other opening end 3B of the mounting hole 3 is used as a reference surface, and as shown in FIG. 5 (b), the contact rib 4A on the boss 4 side is applied to the reference surface. When the structure in which the resin molded product 1 and the foamed resin molded product 2 are positioned and adjusted in the height direction is adopted by bringing them into contact, the reference surface is deformed by the sagging shown in FIG. Since a reference surface (a flat surface without inclination) according to the design document is not obtained, it is difficult to perform such height direction positioning / position adjustment with high accuracy according to the design document.

  When the gap shown in FIG. 6C occurs, the boss 4 inserted into the attachment hole 3 is positioned in the radial direction by the vicinity of the tip of the boss 4 coming into contact with one open end 3A of the attachment hole 3. Only. For this reason, the contact area between the inserted boss 4 and the mounting hole 3 is small, the play of the boss 4 in the mounting hole 3 is large, and the boss 4 tends to wobble. For example, the tip of the inserted boss 4 is foamed. The fastening operation at the time of fastening with respect to the resin molded product 1 becomes unstable, and there are disadvantages such as poor workability of such fastening operation.

JP 2012-254567 A

  The present invention has been made to solve the above-mentioned problems, and its object is to provide a foamed resin suitable for improving the size and position accuracy of the mounting hole in a foamed resin molded product having the mounting hole. It is to provide a molded article and a manufacturing method thereof.

In order to achieve the above object , the present invention includes a step of forming a cavity of a required shape with a movable mold and a fixed mold, a step of injection-filling a foamed resin material in the cavity, and after completion of the injection-filling A foamed resin having mounting holes by reversing the movable mold to secure a foaming space for the foamed resin material between the movable mold and the fixed mold and foaming the foamed resin material. A method for manufacturing a molded article, wherein a core for forming the mounting hole is formed on an inner surface of the movable mold forming the cavity, and a first rib is formed on one opening edge of the mounting hole. And a second groove for forming a second rib on the other opening edge of the mounting hole on the inner surface of the stationary mold forming the cavity. A groove is provided, Before the movable mold is retracted when securing the mold, the foamed resin material injected and filled in the first and second grooves is cooled and solidified without foaming. When the first and second ribs made of a foamed resin material are formed and the movable mold is retracted when the foaming space is secured, the entire periphery of the mounting hole formed by the core is attached. As a means for evenly pulling the hole in the vertical direction, the first rib is engaged with the first groove, and one opening end of the mounting hole is fixedly locked to the movable mold side. in the state, and that the second rib is in the other state in which near the open end is fixed locked to the fixed mold side of said second groove to engage the attachment holes Features.

  In the present invention, as a specific configuration of the foamed resin molded product having the mounting hole, as described above, the first rib is formed when the movable mold is retracted when the foaming space is secured. The first groove is engaged with the first groove and the vicinity of one opening end of the mounting hole is fixedly locked to the movable mold side, and the second rib is used to form the second groove. The size and position accuracy of the mounting hole is improved by engaging with the groove of the mounting hole and the vicinity of the other opening end of the mounting hole is fixed and locked to the fixed mold side. In the provided foamed resin molded product, it is possible to provide a foamed resin molded product suitable for improving the dimensional accuracy of the mounting hole, and a method for manufacturing the same.

1A is an exploded plan view showing an outline of a door trim which is an interior part for an automobile to which the present invention is applied, FIG. 1B is an enlarged cross-sectional view taken along line BB in FIG. 1A, and FIG. FIG. 2 is an enlarged sectional view taken along the line CC in FIG. 2A is a plan view of a state where the foamed resin molded product (door trim lower) and the resin molded product (door trim upper) of FIG. 1 are joined, and FIG. 2B is a DD line in FIG. 2A. FIG. (A) in FIG. 3 is an enlarged view of a portion where the vicinity of the mounting hole is molded in a molding die when the foamed resin molded article having the mounting hole of FIG. 1 is manufactured by injection molding of a foamed resin material. Sectional drawing of a mold, (b) is a diagram showing an outline of the vicinity of an attachment hole made by the molding mold, and (c) is an enlarged sectional view taken along line EE in FIG. 3 (b). 4A is an exploded plan view showing an outline of a conventional door trim that is an interior part for an automobile, FIG. 4B is an enlarged cross-sectional view taken along line BB in FIG. 4A, and FIG. The CC sectional view enlarged view in (a). 5A is a plan view of a state in which the foamed resin molded product (door trim lower) and the resin molded product (door trim upper) of FIG. 4 are joined, and FIG. 5B is a DD line in FIG. 4A. FIG. 6A is an enlarged view of a portion where the vicinity of the mounting hole is molded in a molding die when the foamed resin molded product having the mounting hole of FIG. 4 is manufactured by injection molding of a foamed resin material. Sectional drawing of the mold, (b) is a diagram showing an outline of the vicinity of the mounting hole produced by the molding mold, and (c) is an enlarged sectional view taken along line EE in FIG. 6 (b).

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1A is an exploded plan view showing an outline of a door trim which is an interior part for an automobile to which the present invention is applied, FIG. 1B is an enlarged cross-sectional view taken along line BB in FIG. ) Is a cross-sectional enlarged view taken along the line CC in FIG. 2A is a plan view of a state where the foamed resin molded product (door trim lower) and the resin molded product (door trim upper) of FIG. 1 are joined, and FIG. 2B is a plan view of FIG. It is a DD sectional view enlarged view.

  The door trim DT as the automobile interior part shown in FIG. 1 (a) is manufactured by manufacturing the door trim lower DT1 as the foamed resin molded product 1, and separately manufacturing the door trim upper DT2 as the resin molded product 2. A resin molded product 2 is attached and joined to the foamed resin molded product 1 (see FIGS. 2A and 2B).

  For example, as shown in FIGS. 1B and 1C, the resin-molded product 2 (door trim upper DT2) is attached to the foamed resin-molded product 1 (door trim lower DT1). The boss 4 of the resin molded product 2 is inserted into the mounting hole 3, and the tip of the inserted boss 4 is fastened to the foamed resin molded product 1 as shown in FIG. In FIG.2 (b), as an example of the fastening method, the front-end | tip part of the boss | hub 4 which protruded from the attachment hole 3 is fastened by the crimping process by heat melting.

  By the way, in the foamed resin molded product 1 provided with the mounting holes 3 in FIG. 1B, for example, a step of forming a cavity 103 of a required shape with the movable mold 101 and the fixed mold 102 shown in FIG. And a step of injecting and filling a foamed resin material into the cavity 103, and a reversing operation of the movable mold 101 after the completion of the injection and filling so that the foamed resin material is inserted between the movable mold 101 and the fixed mold 102. A foaming space can be secured and the foamed resin material can be foamed.

  In the foamed resin molded product 1 provided with the mounting hole 3 in FIG. 1B, of the opening ends 3A and 3B of the mounting hole 3, the edge of one opening end 3A is made of a non-foamed resin material. One rib RB1 is provided, and a second rib RB2 made of an unfoamed resin material is also provided at the edge of the other opening end 3B.

  By the way, in the molding die 100 shown in FIG. 3A, when the movable die 101 is retracted when the foaming space is secured, the first die RB1 is used to form the movable die. It is engaged with the first groove 105 on the 101 side and the vicinity of one opening end 3A of the mounting hole 3 is fixedly locked to the movable mold 101 side, and the second rib RB2 1 is engaged with the second groove 106 on the fixed mold 102 side to be formed and the vicinity of the other opening end 3B of the mounting hole 3 is fixedly locked to the fixed mold 102 side. The dimension / position accuracy of the mounting hole 3 in (b) is enhanced. The principle will be described later.

  FIG. 3A is an enlarged view of a portion where the vicinity of the mounting hole is molded in a molding die when the foamed resin molded article having the mounting hole of FIG. 1 is manufactured by injection molding of a foamed resin material. Sectional drawing of the mold, (b) is a diagram showing an outline of the vicinity of the mounting hole produced by the molding mold, and (c) is an enlarged sectional view taken along the line EE in FIG. 3 (b).

  In the molding die 100 of FIG. 3, a cavity 103 having a required shape is formed by a movable die 101 and a fixed die 102.

  On the inner surface of the movable mold 101 forming the cavity 103, a core 104 for forming the mounting hole 3 in FIG. 1B and a first rib RB1 at the edge of one opening end 3A of the mounting hole 3 are provided. And a first groove 105 for forming. The first groove 105 is annular, and the first groove 105 is also filled with a foamable resin material.

  Further, a second rib RB2 (see FIG. 1B) is formed on the inner surface of the fixed mold 102 forming the cavity 103 at the other opening end 3B edge of the mounting hole 3. A groove 106 is provided. The second groove 106 is also annular, and the second groove 106 is also filled with a foamable resin material.

  In the molding die 100 shown in FIG. 3, the step of injecting and filling the foamed resin material into the cavity 103 from an injection gate (not shown), and the movable die 101 is retracted after completion of the injection and filling, so that the movable die is moved. A foamed resin molded article having the mounting holes 3 in FIG. 1 is obtained by securing a foaming space for the foamed resin material between the mold 101 and the fixed mold 102 and foaming the foamed resin material. 1 is manufactured.

  The foamed resin material is obtained by mixing a foaming agent in a thermoplastic resin. Examples of the thermoplastic resin include polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, vinyl chloride. May be appropriately selected from a series resin, polyamide resin, polyacetal resin, polycarbonate resin, ionomer resin, acrylonitrile / butadiene / styrene (ABS) resin, and the like. Moreover, as a foaming agent, organic foaming agents, such as azodicarbonamide, or inorganic foaming agents, such as sodium bicarbonate, can be used, for example.

  By the way, in the molding die 100 of FIG. 3, the retracting operation of the movable die 101 when securing the foaming space as described above is performed. Before that, the first and first described above are performed in advance. When the foamed resin material injected and filled in the two grooves 105 and 106 is cooled and solidified without foaming in the grooves 105 and 106, the first and second ribs RB1 and RB2 ( 1B) is formed.

  The cooling and solidification of the foamed resin material in the non-foamed state in the first and second grooves 105 and 106 as described above also occurs in places other than the grooves 105 and 106. That is, the foamed resin material injected and filled into the cavity 103 is hot melted and has a high temperature, but before the reversing operation of the movable mold 101 for securing the foaming space is performed, the movable mold 101 and the fixed mold are used. The foamed resin material 102 that has melted the heat 102 is deprived of heat, whereby the surface layer of the foamed resin material in contact with the movable mold 101 and the fixed mold 102 is cooled and solidified relatively early without being foamed. The surface layer of the foamed resin material thus cooled and solidified without foaming is a material having high strength and hardness as the solid layer S, like the first and second ribs RB1 and RB2 described above. . Inside the solid layer S is a foam layer T.

  Further, in the molding die 100 of FIG. 3, when the movable die 101 is retracted when the foaming space is secured, the first rib RB1 is engaged with the first groove 105 and the mounting hole 3 is engaged. The one open end 3A is fixedly locked to the movable mold 101 side (the first rib RB1 does not come out of the groove 105), and the second rib RB2 is the second groove 106. In the same manner, the vicinity of the other opening end 3B of the mounting hole 3 is fixedly locked to the fixed mold 102 side (the second rib RB2 does not come out of the groove 105). Thereby, the dimension and position accuracy of the mounting hole 3 to be formed are increased. The principle is as follows.

<< Principle of increasing mounting hole 3 dimensions and position accuracy >>
In the molding die 100 of FIG. 3A, when the movable die 101 is retracted when securing the foaming space, the one opening end 3A edge of the mounting hole 3 is made of an unfoamed resin material. The first rib RB <b> 1 is already completed with the first rib RB <b> 1 engaged in the first groove 105 of the movable mold 101. At the same time as the completion, the second rib RB2 made of an unfoamed resin material is already engaged with the second groove 106 of the fixed mold 102 at the other opening end 3A edge of the mounting hole 3 as well. It has been completed.

  The completed first and second ribs RB1 and RB2 engage with the corresponding grooves 105 and 106, respectively, and the vicinity of one opening end 3A of the mounting hole 3 is fixed and locked to the movable mold 101 side, A state in which the vicinity of the other opening end 3B of the mounting hole 3 is fixedly locked to the fixed mold 102 side, that is, no ribs RB1 and RB2 come out of the grooves 105 and 106 (hereinafter referred to as “both locked state”). Then, the retracting operation of the movable mold 101 when securing the foaming space is performed. If it does so, the whole attachment hole 3 will be pulled in the up-down direction substantially equally with sufficient balance through the 1st, 2nd rib RB1, RB2 located in the up-down direction of the attachment hole 3. For this reason, according to the manufacturing method of the foamed resin molded product 1 using the molding die 100 of FIG. 3, the occurrence of the sag and the gap shown in FIG. Increases accuracy.

  Therefore, for example, as shown in FIG. 1 (b), the vicinity of the other opening end 3B of the mounting hole 3 is used as a reference surface, and as shown in FIG. 2 (b), the contact rib 4A on the boss 4 side is provided on the reference surface. When the structure in which the resin molded product 1 and the foamed resin molded product 2 are positioned and adjusted in the height direction is adopted by bringing them into contact with each other, the reference surface is affected by the aforementioned sagging as shown in FIG. Therefore, it is easy to perform such height direction positioning and position adjustment with high accuracy according to the design document.

  Further, according to the method of manufacturing the foamed resin molded article 1 using the molding die 100 of FIG. 3, the occurrence of the skies shown in FIG. 6C is effectively prevented as described above. The contact area with the boss 4 inserted into the boss 4 is increased, the play of the boss 4 in the mounting hole 3 is less, and the boss 4 is less likely to wobble. There is also an advantage that the fastening operation at the time of fastening can be performed stably.

  Furthermore, according to the manufacturing method of the foamed resin molded article 1 using the molding die 100 of FIG. 3, as described above, the entire mounting hole 3 is pulled substantially uniformly in a balanced manner in the vertical direction. A recess 1A is formed in the skin layer S as shown in FIG. 3A around the ribs RB1 and RB2, but the recess 1A does not affect the strength of the foamed resin molded product 1. Rather, when the tip end portion of the boss 4 is crimped by heating and melting, an anchor effect is obtained by the molten resin biting into the concave portion 1A. The advantageous effect that the mounting joint strength of the resin molded product 2 with respect to is increased.

<< Dimensional configuration of the first and second ribs RB1, RB2 >>
In FIG. 3C, the plate thickness t of the first and second ribs RB1 and RB2 is set to a plate thickness at which the ribs RB1 and RB2 do not foam, such as 2.0 mm or less. This is because if these ribs RB1 and RB2 are foamed, the strength of the ribs RB1 and RB2 is reduced, and it is difficult to maintain the above-described both-locked state.

  The height h of the second rib RB1 varies depending on the backward stroke amount of the movable mold 101 when securing the foaming space. For example, if the backward stroke amount is 1 mm, the height of the second rib RB2 h is set higher than 1 mm (1 mm> h). That is, the height of the second rib RB2 is set to be higher than the reverse stroke amount of the movable mold 101. When this condition is not satisfied, the second rib RB2 is detached from the groove 106 when the movable mold 101 is retracted when securing the foaming space, and it is difficult to maintain the above-described both-locked state. Because it becomes.

DESCRIPTION OF SYMBOLS 1 Foamed resin molded product 1A Concave part 2 Resin molded product 3 Mounting hole 3A One opening end 3B of a mounting hole The other opening end 4 of a mounting hole 4 Boss 4A Abutting rib 100 Molding die 101 Movable die 102 Fixed die 103 Cavity 104 Core 105 First groove 106 Second groove DT Door trim DT1 Door trim lower DT2 Door trim upper S Skin layer T Foamed layer RB Rib RB1 First rib RB2 Second rib

Claims (1)

A step of forming a cavity having a required shape with a movable mold and a fixed mold, a step of injecting and filling a foamed resin material in the cavity, and a movable mold by retreating the movable mold after completion of the injection and filling. Securing a foaming space of the foamed resin material between a mold and a fixed mold, and a step of foaming the foamed resin material, a method of producing a foamed resin molded product having mounting holes,
On the inner surface of the movable mold forming the cavity, a core for forming the mounting hole, a first groove for forming a first rib at one opening edge of the mounting hole, Is provided,
A second groove for forming a second rib is provided on the other opening edge of the mounting hole on the inner surface of the fixed mold that forms the cavity,
Before the reversing operation of the movable mold when securing the foaming space is performed, the foamed resin material injected and filled in the first and second grooves in advance is cooled and solidified without being foamed, First and second ribs made of unfoamed resin material are formed,
As means for ensuring that the entire periphery of the mounting hole formed by the core is evenly pulled in the vertical direction of the mounting hole when the movable mold is retracted when securing the foaming space , The first rib engages with the first groove, and the vicinity of one opening end of the mounting hole is fixedly locked to the movable mold side, and the second rib is the first method for producing a foamed resin molded article, wherein the vicinity of the other open end of engaging the attachment hole 2 of the groove is in the fixed locked to the fixed mold side.

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