JP4842026B2 - Plastic molded product - Google Patents

Description

  In the present invention, the component mounting boss part is integrally projected on the panel-shaped molded product body, and a skin layer having a high resin density is formed on the boss part and the surface of the molded product body. The present invention relates to a resin molded product having a foam layer having a lower resin density than the skin layer.

In Patent Document 1, in a state in which a fixed mold having a recess formed on a molding surface and a movable mold incorporating a slide mold are closed, a fiber and a thermoplastic resin containing a foam material are injected and filled into the cavity. In the process of solidifying the thermoplastic resin in the movable mold, a rigid skin layer without voids is formed on the entire surface by retracting the slide mold in the cavity volume expansion direction and foaming the thermoplastic resin in the movable mold. In addition, a resin molded product in which a foam layer having a large number of voids is formed is obtained. And in this resin molded product, weight reduction can be achieved by the said foaming layer.
Japanese Patent Laid-Open No. 11-179751 (pages 3 and 7, FIG. 1)

  By the way, when the resin molded product has a component mounting boss portion having a tapping screw insertion hole such as a resin door module plate constituting a part of a side door of an automobile, the boss portion includes a tapping screw. Since the tightening force due to screwing is strong, it is necessary to secure rigidity by thickening the area around the tapping screw insertion hole of the boss portion.

  However, when using foamed thermoplastic resin, if the area around the tapping screw insertion hole in the boss is thickened, the surface side solidifies early due to the influence of the mold temperature, and a thin skin layer is formed. Due to the delay in solidification progress, the thermoplastic resin is foamed by the foam material to form a foamed layer.Therefore, when the tapping screw is screwed into the tapping screw insertion hole, the compressive force in the anti-screwing direction is applied to the skin layer around the tapping screw insertion hole. As a result, a crack occurs on the inner peripheral surface of the tapping screw insertion hole. In this way, when a crack occurs, the foam layer is exposed on the inner surface of the tapping screw insertion hole, and even if the tapping screw is screwed in, the inner surface of the tapping screw insertion hole collapses and the fastening force of the tapping screw does not work, which hinders component mounting. Will come.

  The present invention has been made in view of this point, and an object of the present invention is to provide a resin molded product in which cracks do not occur on the inner peripheral surface of the tapping screw insertion hole of the boss portion.

  In order to achieve the above object, the present invention is characterized in that the vicinity of the opening of the tapping screw insertion hole of the boss is reinforced.

Specifically, according to the present invention, a component mounting boss having a tapping screw insertion hole is integrally projected on the mounting seat surface portion of the panel-shaped molded product body , and the screw insertion side opening of the tapping screw insertion hole is provided. opened to the mounting seat surface side, the fitting as tapping screw insertion hole formed in the mounting part corresponding to tapping screw insertion hole of the boss portion in a state superimposed on the mounting seat surface portion, a tapping screw The following solution was taken for a resin molded product in which the attachment component is attached to the boss portion by being screwed into the screw insertion side opening of the tapping screw insertion hole from the tapping screw insertion hole.

That is, according to the first aspect of the present invention, a skin layer is formed in the vicinity of the molding surface of the molding die of the thermoplastic resin containing the foam layer forming substance injected and filled in the cavity of the molding die in the boss portion and the molded product body. At that time, by expanding the cavity volume and foaming the thermoplastic resin, a skin layer having a high resin density is formed on the surface and has a large number of voids and a resin density lower than that of the skin layer. A foam layer is formed inside, and a solid layer thicker than the skin layer is formed in the vicinity of the screw insertion side opening of the tapping screw insertion hole of the boss portion.

  According to a second aspect of the present invention, in the first aspect of the present invention, the end surface of the solid layer of the boss portion is formed substantially flush with the mounting seat surface portion so as to abut or approach the mounting component. A concave portion is formed between the end surface of the layer and the mounting seat surface portion.

  According to a third aspect of the present invention, in the first aspect of the present invention, the end surface of the solid layer of the boss portion is closer to the head of the tapping screw within the tapping screw insertion hole of the mounting component than the mounting seat surface portion. Is also protruding.

According to the first aspect of the present invention, the skin layer is formed on the surface of the boss portion and the molded product body, and the foamed layer having a large number of voids is formed inside, thereby reducing the weight of the resin molded product. it can. On the other hand, since a solid layer thicker than the skin layer is formed in the vicinity of the screw insertion side opening of the tapping screw insertion hole of the boss portion, anti-screwing that acts by screwing the tapping screw into the tapping screw insertion hole The thick solid layer can sufficiently resist the compressive force in the direction, the tapping screw insertion hole does not crack, and the tapping screw insertion hole does not collapse. Thus, the mounting accuracy and mounting strength of the mounting component, that is, the fastening force of the tapping screw can be increased.

  According to the invention which concerns on Claim 2, since the recessed part is formed in the outer periphery of the solid layer of a boss | hub part, the said solid layer can be reliably formed by quick mold temperature transmission in the case of shaping | molding. Further, since the end surface of the solid layer contacts the mounting part by screwing the tapping screw into the tapping screw insertion hole, the solid layer is not forced into the tapping screw insertion hole of the mounting part, and the tapping screw insertion hole Can be prevented from being damaged.

  According to the third aspect of the present invention, the thickness of the tapping screw of the solid layer is increased by the amount that the solid layer of the boss portion is close to the head of the tapping screw in the tapping screw insertion hole of the mounting part. The tapping screw insertion hole can be reliably prevented from being damaged.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 3 is a sectional view of the side door 1 of the automobile. The side door 1 includes a metal door main body 7 including a door outer panel 3 and a door inner panel 5. The door inner panel 5 of the door main body 7 has a carrier plate (door) as a resin molded product according to the first embodiment. A module plate 9 is fastened by a bolt 11 and a weld nut 13, and a resin door trim 15 is attached to the door inner panel 5 so as to cover the carrier plate 9 from the vehicle interior side. In FIG. 3, 17 is a sealing material interposed between the outer peripheral edge of the door inner panel 5 and the outer peripheral edge of the carrier plate 9.

  The carrier plate 9 is mixed with a foamed layer forming material such as a chemical foaming material that generates gas by a chemical reaction, an inert gas (physical foaming material) such as carbon dioxide gas and nitrogen gas, and fibers such as glass fibers. A panel-like plate main body 19 is provided as a molded product main body which is molded with the thermoplastic resin thus formed. As shown in FIG. 2, a plurality of circular boss-like attachment portions 21 for attaching the carrier plate 9 to the door inner panel 5 are integrally projected on the front and back sides of the outer peripheral edge portion of the plate body 19. .

A cylindrical speaker mounting portion 23 is integrally projected on the side of the vehicle interior of the plate body 19 corresponding to the lower left corner in FIG. 2, and the speaker mounting portion 23 is attached to the tip of the cylindrical body portion 24 in an annular shape. the seat surface 25 ing is integrally projected in the inner direction. As shown in FIG. 1, speaker mounting boss portions 27 as component mounting boss portions having tapping screw insertion holes 27a are integrated with the back surface of the mounting seat surface portion 25 one by one at a position that divides the circumference into four equal parts. The screw insertion side opening 27b of the tapping screw insertion hole 27a is open to the mounting seat surface 25 side .

As shown in FIG. 1, the boss portion 27 and the plate main body 19 are provided with a molding die 49 (fixed die 45, movable die 47) of the thermoplastic resin R injected and filled into a cavity 51 of a molding die 49 described later. When the skin layer 29 is generated in the vicinity of the molding surfaces 45a and 47a, the cavity volume is expanded and the thermoplastic resin R is foamed to form a hard skin layer 29 having no voids and high resin density on the surface. In addition, a foam layer 31 having a large number of voids (not shown) and having a resin density lower than that of the skin layer 29 is formed inside. A solid layer 33 that is thicker than the skin layer 29 is formed near the screw insertion side opening 27b of the tapping screw insertion hole 27a of the boss portion 27. This is the greatest feature of the present invention. In FIG. 3, the plate body 19 is shown as a single layer for the convenience of drawing. Further, the end surface of the solid layer 33 of the boss portion 27 is formed to be substantially flush with the mounting seat surface portion 25 so as to contact the back surface of the flange portion 37 of the cylindrical speaker housing member 35 as the mounting component. An annular recess 39 is formed between the end face 33 and the surrounding mounting seat surface 25 so as to surround the tapping screw insertion hole 27a. The end surface of the solid layer 33 of the boss portion 27 may be brought close to the back surface of the flange portion 37 of the speaker housing member 35 with a small gap. A plurality of the concave portions 39 may be formed at intervals in the circumferential direction, and the shape thereof may be linear or circular.

In the flange portion 37 of the speaker housing member 35, tapping screw insertion holes 37 a are formed penetrating one by one at positions that divide the circumference into four equal parts so as to correspond to the tapping screw insertion holes 27 a of the boss portion 27. . Then, the speaker housing member 35 is inserted into the speaker mounting portion 23 from the vehicle interior side of the plate body 19 so that the tapping screw insertion hole 37a corresponds to the tapping screw insertion hole 27a (opening portion 27b) of the boss portion 27. Further, the shaft portion 41a of the tapping screw 41 is inserted from the tapping screw insertion hole 37a to the screw insertion side of the tapping screw insertion hole 27a in a state where the rear surface of the flange portion 37 of the speaker housing member 35 is overlapped with the mounting seat surface portion 25 of the boss portion 27. The speaker housing member 35 is attached to the boss portion 27 by screwing into the opening portion 27b and clamping the flange portion 37 of the speaker housing member 35 with the back surface of the head portion 41b of the tapping screw 41 and the mounting seat surface portion 25. ing. In FIG. 3, reference numeral 43 denotes a speaker grill formed on the door trim 15 so as to correspond to the speaker housing member 35.

  Next, the procedure for forming the carrier plate 9 will be described.

  First, as shown in FIG. 4, a mold 49 composed of a fixed mold 45 and a movable mold 47 is closed. The molding surface 45a of the fixed mold 45 is formed corresponding to the back surface shape of the plate body 19 and the speaker mounting portion 23, and the molding surface 45a has a circular shape corresponding to the outer surface shape of the boss portion 27 of the speaker mounting portion 23. A recess 45b is formed. On the other hand, the molding surface 47a of the movable mold 47 is formed corresponding to the surface shapes of the plate body 19 and the speaker mounting portion 23, and the molding surface 47a has a hole shape of the tapping screw insertion hole 27a of the boss portion 27. Is formed integrally with a projecting portion 47b, and an annular projecting portion 47c corresponding to the concave shape of the recessed portion 39 is formed around the projecting portion 47b. A cavity 51 for molding the carrier plate 9 is formed between the molding surface 45 a of the fixed mold 45 and the molding surface 47 a of the movable mold 47. The cavity width W1 in the circular recess 45b corresponding to the thickness around the tapping screw insertion hole 27a of the boss portion 27 of the cavity 51 is formed larger than the cavity width W2 corresponding to the thickness of the plate body 19. Yes. And the cavity width W3 corresponding to the trunk | drum 24 of the speaker attachment part 23 in the meantime is formed in the width | variety equivalent to the said cavity width W2.

  Next, the cavity 51 of the mold 49 is injected and filled with a thermoplastic resin R (for example, polypropylene resin) in which the foam layer forming material and fibers such as glass fibers are mixed from an injection machine (not shown). It introduces into the recess 45b. FIG. 4 shows this injection filling state.

  Thereafter, the skin layer 29 is generated in the vicinity of the molding surfaces 45a and 47a of the mold 49 by the solidification of the thermoplastic resin R injected and filled into the cavity 51 of the mold 49. It has not solidified.

  When the skin layer 29 is generated, as shown in FIG. 5, the movable die 47 is retracted in the cavity volume expansion direction C (die opening direction). In other words, the movable die 47 is slightly separated from the fixed die 45, and the cavity volume is increased by, for example, twice or more. At this stage, the portion of the thermoplastic resin R that contacts the molding surfaces 45a and 47a of the mold 49 is cooled early due to the influence of the mold temperature. Constitute. On the other hand, the inner part of the thermoplastic resin R is hardly affected by the mold temperature and is in a gel state with high viscosity.

Therefore, due to the expansion of the cavity volume, the plate main body 19, the mounting seat surface portion 25, and the bottom surface portion 27 c of the boss portion 27 facing the cavity volume expansion direction C have been thermoplastically compressed by the fixed mold 45 and the movable mold 47 so far. While the resin R is pulled by the molding surface 47a of the movable mold 47, the gas generated by the chemical reaction in the thermoplastic resin R and the inert gas are diffused into the enlarged cavity 51, and the thermoplastic resin R is foamed. At this time, the fibers in the thermoplastic resin R are also elastically restored by reducing the compression, and the foaming of the thermoplastic resin R is assisted by this elastic restoring force (spring back phenomenon). As a result, the plate body 19, the mounting seat surface portion 25, and the bottom surface portion 27 c of the boss portion 27 are formed with a solid skin layer 29 on the surface without a space, and have a large number of spaces (not shown) inside. A foam layer 31 is formed. However, the space between the protrusion 47b of the movable mold 47 and the annular protrusion 47c is narrow, and the thermoplastic resin R therebetween is cooled early due to the influence of the mold temperature, so that the tapping screw insertion hole 27a of the boss 27 is A solid layer 33 that is thicker than the skin layer 29 is formed in the vicinity of the screw insertion side opening 27b.

  On the other hand, the body portion 24 of the speaker mounting portion 23 extending substantially along the cavity volume expansion direction C hardly increases the cavity volume even when the movable mold 47 is retracted, and the cavity width W3 is the cavity width of the circular recess 45b. Since it is smaller than W1, it is cooled early due to the influence of the mold temperature and becomes a solid layer 33 having no voids and being solid. However, the circular recess 45b corresponding to the thickness around the tapping screw insertion hole 27a of the boss 27 in the cavity 51 extends along the cavity volume expansion direction C, and the cavity volume does not change even when the movable die 47 is retracted. Although the cavity width W1 is formed to be larger than the cavity width W2 corresponding to the wall thickness of the plate body 19, the thermoplastic resin R is hardly affected by the mold temperature and is solidified. The thermoplastic resin R foams due to the gas or inert gas generated by the chemical reaction of the foam layer forming substance in the thermoplastic resin R during this time, which takes longer than other parts. A foam layer 31 is formed inside. The resin density of the foam layer 31 is slightly higher than the resin density of the foam layer 31 of the plate body 19 because the cavity volume hardly increases as described above.

  As described above, the skin layer 29 is formed on the entire surface of the boss portion 27 and the plate body 19 and a large number of voids are formed therein, whereby the weight of the carrier plate 9 can be reduced.

Since the solid layer 33 thicker than the skin layer 29 is formed in the vicinity of the screw insertion side opening 27b of the tapping screw insertion hole 27a of the boss portion 27, the speaker housing member 35 is attached to the speaker attachment portion 23. The thick solid layer 33 can sufficiently resist the compressive force in the anti-screwing direction acting by screwing the tapping screw 41 into the tapping screw insertion hole 27a, and the inner peripheral surface of the tapping screw insertion hole 27a is cracked. The tapping screw 41 can be securely screwed into the tapping screw insertion hole 27a without causing the inner peripheral surface of the tapping screw insertion hole 27a to collapse, and the mounting accuracy and the mounting strength of the speaker housing member 35, that is, the fastening of the tapping screw 41 is secured. You can increase your power.

  Furthermore, since the recess 39 is formed around the solid layer 33 in the boss portion 27, the solid layer 33 can be reliably formed by rapid mold temperature transmission during molding. Further, the end surface of the solid layer 33 comes into contact with the rear surface of the flange portion 37 of the speaker housing member 35 by screwing the tapping screw 41 into the tapping screw insertion hole 27a, so that the solid layer 33 is inserted into the tapping screw insertion hole 37a of the speaker housing member 35. The layer 33 is not pushed in forcibly, and the tapping screw insertion hole 27a can be prevented from being damaged.

(Embodiment 2)
FIG. 6 is a view corresponding to FIG. 1 in a state in which the speaker housing member 35 is attached to the boss portion 27 of the speaker attachment portion 23 in the second embodiment.

  In the second embodiment, the end surface of the solid layer 33 of the boss portion 27 is closer to the head 41b of the tapping screw 41 in the tapping screw insertion hole 37a of the flange portion 37 of the speaker housing member 35 than the mounting seat surface portion 25. Is also prominent. The other parts are the same as those in the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. Therefore, in the second embodiment, in addition to the same effects as those of the first embodiment, the solid layer 33 of the boss portion 27 is tapped screw in the tapping screw insertion hole 37a of the flange portion 37 of the speaker housing member 35. The length of the tapping screw 41 of the solid layer 33 in the screwing direction is longer by the amount closer to the head 41b of the 41, and the tapping screw insertion hole 27a can be reliably prevented from being damaged.

(Embodiment 3)
FIG. 7 is a view corresponding to FIG. 1 in a state in which the speaker housing member 35 is attached to the boss portion 27 of the speaker attachment portion 23 in the third embodiment.

The third embodiment is different from the first and second embodiments in that the concave portion 39 is not formed between the end surface of the solid layer 33 and the mounting seat surface portion 25 around the solid layer 33. However, the tapping screw insertion hole 27a of the boss portion 27 is different. This is the same as the first and second embodiments in that a solid layer 33 thicker than the skin layer 29 is formed in the vicinity of the screw insertion side opening 27b. In the third embodiment, the end surface of the solid layer 33 protrudes from the mounting seat surface portion 25 so as to approach the head portion 41 b of the tapping screw 41 in the tapping screw insertion hole 37 a of the flange portion 37 of the speaker housing member 35. This is common with the second embodiment. However, the length of the tapping screw 41 of the solid layer 33 in the screwing direction is shorter than that of the second embodiment because there is no recess 39. The other parts are the same as those in the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. Therefore, in the third embodiment, in addition to the same operational effects as in the first embodiment, the solid layer 33 of the boss portion 27 is tapped on the flange portion 37 of the speaker housing member 35 as in the second embodiment. The thickness of the tapping screw 41 of the solid layer 33 in the screwing direction is thick, that is, the length in the same direction is long, and the tapping screw insertion hole 27a is longer than the head 41b of the tapping screw 41 in the screw insertion hole 37a. Can be reliably prevented.

  In the second and third embodiments described above, the end surface of the solid layer 33 of the boss portion 27 is attached to the flange portion 37 of the speaker housing member 35 with the speaker housing member 35 attached to the speaker attachment portion 23 (in a fastening state). Although the head 41b of the tapping screw 41 is approached in the tapping screw insertion hole 37a, the end surface of the solid layer 33 of the boss portion 27 may be brought into contact with the back surface of the head 41b of the tapping screw 41 in this state. .

  In each of the above embodiments, fibers such as glass fibers are mixed in the thermoplastic resin, but the fibers do not necessarily have to be mixed.

  Furthermore, in each of the above-described embodiments, the case where the speaker housing member 35 is attached to the boss portion 27 of the speaker attachment portion 23 is exemplified, but the present invention can also be applied when attaching the pull handle of the side door 1 to the door trim 15. In this case, tapping screw insertion holes are respectively formed in the pull handle and the door trim 15, and the tapping screws are screwed into the tapping screw insertion holes and the tapping screw insertion holes of the boss portion on the carrier plate side, so that the pull handle and the door trim 15 are formed. And the three members of the carrier plate 9 are fastened together.

  Furthermore, in each of the above-described embodiments, the case where the resin molded product is the carrier plate 9 of the side door 1 of the automobile has been shown. However, other automobile panels such as instrument panels, door trims and trunk boards, and other than automobiles are used. It can also be applied to home appliances, residential panels, and the like.

  In the present invention, the component mounting boss part is integrally projected on the panel-shaped molded product body, and a skin layer having a high resin density is formed on the boss part and the surface of the molded product body. It is useful for a resin molded product having a foam layer having a lower resin density than the skin layer.

FIG. 3 is a cross-sectional view corresponding to the line AA in FIG. 2 with the speaker housing member attached in the first embodiment. It is the perspective view which looked at the carrier plate which concerns on Embodiment 1 from the vehicle interior side. It is sectional drawing equivalent to the BB line of FIG. 2 of the side door of the motor vehicle to which the carrier plate which concerns on Embodiment 1 was applied. FIG. 2 is a molding process diagram corresponding to FIG. 1 showing a state in which a thermoplastic resin is injected and filled into a cavity of a molding die in the first embodiment. FIG. 5 is a molding process diagram showing a state where the movable mold of the molding die in FIG. 4 is slightly retracted in the direction in which the cavity volume is enlarged. FIG. 3 is a diagram corresponding to FIG. FIG. 6 is a view corresponding to FIG. 1 of Embodiment 3.

9 Carrier plate (resin molded product)
19 Plate body (molded product body)
25 Mounting seat surface portion 27 Boss portion 27a Tapping screw insertion hole 27b Screw insertion side opening 29 Skin layer 31 Foam layer 33 Solid layer 35 Speaker housing member (mounting part)
37a Tapping screw insertion hole 39 Recess 41 Tapping screw 41b Tapping screw heads 45a, 47a Molding surface 49 Mold 51 Cavity R Thermoplastic resin

Claims (3)

A component mounting boss portion (27) having a tapping screw insertion hole (27a) is integrally protruded from the mounting seat surface portion (25) of the panel-shaped molded product body (19) so that the tapping screw insertion hole (27a) screw insertion side opening (27b) is opened to the mounting seat surface portion (25) side, tapping screw insertion hole of the tapping screw insertion hole (37a) is the boss portion formed in the mounting part (35) (27) ( the fitting (35) so as to correspond to 27a) in a state superimposed on the mounting seat surface portion (25), tapping screw insertion hole tapping screws (41) from said tapping screw insertion hole (37a) of (27a) A resin molded product (9) in which the mounting part (35) is attached to the boss part (27) by screwing into the screw insertion side opening (27b) ,
The boss portion (27) and the molded article body (19) is molded of the mold (49) of the cavity (51) injected and charged with foamed layer forming material containing a thermoplastic mold resin (R) into (49) When the skin layer (29) is formed in the vicinity of the surfaces (45a, 47a) , by expanding the cavity volume and foaming the thermoplastic resin (R) , the skin layer (29) having a high resin density is formed on the surface. The foam layer (31) having a large number of voids and a lower resin density than the skin layer (29) is formed inside,
In the vicinity of the screw insertion side opening (27b ) of the tapping screw insertion hole (27a) of the boss portion (27) , a solid layer (33) thicker than the skin layer (29 ) is formed. Characteristic resin molded product. In the resin molded product according to claim 1,
The end surface of the solid layer (33) of the boss portion (27) is formed substantially flush with the mounting seat surface portion (25) so as to contact or approach the mounting component (35) , and the end surface of the solid layer (33) . And a mounting seating surface portion (25) around it, and a recess (39) is formed. In the resin molded product according to claim 1,
The end surface of the solid layer (33) of the boss portion (27) is attached to the mounting seat surface portion ( 35b) so as to approach the head (41b) of the tapping screw (41) within the tapping screw insertion hole (37a) of the mounting component (35). 25) A resin molded product characterized by projecting more than the above.

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