JP2006175708A - Resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molding in which no crack is generated in the inner peripheral surface of the screw insertion hole of a boss. <P>SOLUTION: In the resin molding, a thick-wall part 23 is molded integrally on the base end side of the boss 7 for fitting a pull handle having the screw insertion hole 7a. In a door inner panel main body 3 excluding the boss 7 and the thick-wall part 23, while a fiber-containing thermoplastic resin injected/packed in the cavity of a mold is solidified, with the volume of the cavity corresponding to the door inner panel main body 3 excluding the boss 7 and the thick wall-part 23 enlarged, a large number of voids A are formed by expanding the resin by the elastic restoration force of the fibers. The boss 7 and the thick-wall part 23, without enlarging the volume of the cavity corresponding to the boss 7 and the thick-wall part 23 during molding, are made a hard solid without the void A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of a resin molded product having a component mounting boss having a screw insertion hole and having a large number of voids formed therein.

In Patent Document 1, a thermoplastic resin containing fibers is injected and filled into a cavity in a state where a fixed mold having a recess formed on a molding surface and a movable mold incorporating a slide mold are closed, and this thermoplastic resin containing fibers While the resin is solidified in the cavity, the slide mold is retracted in the movable mold to expand the volume of the whole cavity, and the elastic heat of the fiber compressed by the resin pressure (spring back phenomenon) causes the heat containing the fiber. By expanding the plastic resin, it is possible to obtain a resin molded product in which convex portions are integrally projected on the molded product body and a large number of voids are formed inside the molded product body.
Japanese Patent Laid-Open No. 11-179751 (pages 3 and 7, FIG. 1)

  By the way, when the resin molded product includes a component mounting boss having a screw insertion hole such as a resin door inner panel (door module) constituting a part of a side door of an automobile, the entire cavity as described above is provided. When the volume is expanded and the fiber-containing thermoplastic resin is expanded, a part of the fiber-containing thermoplastic resin flows out into the enlarged cavity from the boss molding recess on the molding surface. Cracks occur on the surface. In this way, if a crack occurs, an internal gap is exposed on the inner peripheral surface of the screw insertion hole, and even if a tapping screw is screwed in, the inner peripheral surface of the screw insertion hole collapses and the screw does not work, causing troubles in component mounting. become.

  FIG. 1B shows a pull handle mounting boss c projecting integrally with the door inner panel body b of the door inner panel a, and a crack e is generated on the inner peripheral surface of the screw insertion hole d of the boss c. Indicates the state. In FIG.1 (b), f is the reinforcement rib integrally shape | molded radially around the outer periphery of the boss | hub c.

  In FIG. 4B, a speaker housing portion g is integrally projected from the door inner panel body b of the door inner panel a, and a speaker mounting boss h is integrally formed around the speaker housing portion g. The state where the crack j has generate | occur | produced in the inner peripheral surface of the screw insertion hole i is shown. In FIG. 4B, k is a reinforcing rib formed integrally around the outer periphery of the boss h. Moreover, A is a space | gap in FIG.1 (b) and FIG.4 (b).

  The present invention has been made in view of the above points, 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 screw insertion hole of the boss.

  In order to achieve the above object, the present invention is characterized in that the thermoplastic resin containing fibers does not flow out from the concave portion of the mold corresponding to the boss during molding.

  Specifically, the present invention is based on a resin molded product in which a component mounting boss having a screw insertion hole is molded integrally with a molded product body, and has taken the following solution.

  That is, in the invention described in claim 1, a thick portion is integrally formed on the base end side of the boss, and a molded product body excluding the boss and the thick portion is injected and filled into a cavity of a mold. In the process of solidifying the thermoplastic resin containing fibers, the cavity volume corresponding to the molded product main body excluding the boss and the thick part is enlarged, and the above-mentioned thermoplastic resin containing fibers is expanded by the elastic restoring force of the fibers. The boss and the thick part are characterized by being a solid solid without a gap without expanding the cavity volume corresponding to the boss and the thick part during molding.

  According to a second aspect of the present invention, in the above premise, a plurality of protrusions extending along the hole center line direction are integrally projected at intervals in the circumferential direction on the inner peripheral surface of the screw insertion hole of the boss. In the molded product body excluding the boss, the fiber volume is increased by increasing the cavity volume corresponding to the molded product body excluding the boss in the process of solidifying the fiber-filled thermoplastic resin injected into the cavity of the mold. A large number of voids are formed inside by expanding the thermoplastic resin with the elastic restoring force of the fiber, and the above boss does not expand the cavity volume corresponding to the boss at the time of molding, and is a solid solid without voids. Features.

  According to the first aspect of the present invention, a large number of voids are formed inside the molded product main body excluding the boss and the thick wall portion by the elastic restoring force of the fiber compressed by the resin pressure, thereby reducing the weight of the resin molded product. Can be achieved. On the other hand, since the cavity volume corresponding to the boss and the thick wall portion is not enlarged, it is possible to secure the mounting strength of the boss by making the boss a solid solid without voids caused by the outflow of the thermoplastic resin containing fibers. In addition, for the boss molding accompanying the cavity volume expansion corresponding to the molded product main body excluding the boss and the thick part by having the above thick part between the molded product main body excluding the boss and the thick part and the boss base end. Partial outflow of the fiber-containing thermoplastic resin from the recess is restricted, cracks do not occur on the inner peripheral surface of the screw insertion hole of the boss, the strength of the boss is improved, for example, when a tapping screw is screwed into the boss, This screwing can be ensured and the mounting accuracy and mounting strength of the parts can be increased.

  According to the invention which concerns on Claim 2, many voids are formed in the inside of the molded product main body excluding the boss by the elastic restoring force of the fiber compressed by the resin pressure, and the resin molded product can be reduced in weight. it can. On the other hand, since the cavity volume corresponding to the boss is not enlarged, the strength of the boss can be ensured by making the boss a solid solid without voids caused by the outflow of the thermoplastic resin containing fibers. In addition, since there are a plurality of protrusions on the inner peripheral surface of the screw insertion hole of the boss, the contact area between the inner peripheral surface of the screw insertion hole and the mold is increased, and the inner peripheral surface of the screw insertion hole is cooled quickly. Even if a part of the thermoplastic resin containing fibers flows out of the boss molding recess as the cavity volume corresponding to the molded product body excluding the boss increases, the cracks generated on the inner peripheral surface of the screw insertion hole of the boss It is difficult and intermittent to reach the ridge, and when the tapping screw is screwed in while securing the strength of the ridge, this screwing is ensured, and the attachment accuracy and the attachment strength of the parts can be increased.

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

  6 is a perspective view of a resin door inner panel (door module) 1 constituting a part of a side door of an automobile as a resin molded product according to Embodiment 1 of the present invention, as viewed from the vehicle interior side. The door inner panel 1 includes a door inner panel main body 3 as a molded product main body, and four cylindrical mounting seats 5 having screw insertion holes 5a are provided on a surface of the door inner panel main body 3 on the vehicle interior side. The screw insertion hole 5a penetrates the door inner panel main body 3, and a window regulator ascending / descending rail (not shown) for raising and lowering the window glass by inserting a screw into the screw insertion hole 5a. Are attached to the four mounting seats 5.

  Among the four mounting seats 5, a part having a screw insertion hole 7 a into which a tapping screw is screwed on the outer surface of the door inner panel body 3 corresponding to the space between the two upper and lower mounting seats 5 on the right side in FIG. 6. Four pull handle mounting bosses 7 as mounting bosses are integrally protruded on the left and right at equal intervals.

  In FIG. 6, a circular flower pot-shaped speaker housing portion 9 is integrally projected on the outer surface of the door inner panel body 3 corresponding to the lower left corner of the door inner panel body 3, and the door inner panel body 3 corresponding to the speaker housing portion 9 is An annular flange portion 11 is integrally projected on the surface on the vehicle interior side. The flange portion 11 has a screw insertion hole 13a into which a tapping screw is screwed. Are integrally formed one by one at positions that divide the circumference into four equal parts.

  As shown in FIG. 7, a seal surface portion 15 is integrally formed on the outer peripheral edge portion of the vehicle outer surface of the door inner panel body 3 over the entire circumference, and the seal surface portion 15 has a U-shaped cross section. The seal groove 15a is recessed over the entire circumference. A seal material is provided in the seal groove 15a to ensure a seal with the door outer panel.

  A plurality of screw insertion holes 18 are formed so as to penetrate the entire circumference of the door inner panel body 3 from the seal surface 15 of the door inner panel body 3 at predetermined intervals. Around the insertion hole 18, an annular convex portion 19 is projected to form a mounting portion 21. In FIG. 6, 22 is a motor mounting part for raising and lowering the window glass.

  FIG. 1A shows the above-described pull handle mounting boss 7 in an enlarged manner. The pull handle mounting boss 7 and the thick portion 23 are integrally formed on the outer periphery of the pull handle mounting boss 7 on the base end side, and a plurality of reinforcing ribs 25 are integrally formed radially. Furthermore, a large number of gaps A (indicated by X in FIG. 1A) are formed inside the door inner panel body 3 excluding the pull handle mounting boss 7 and the thick portion 23. On the other hand, the pull handle mounting boss 7 and the thick portion 23 are solid solids having no gap A, which is the greatest feature of the present invention. The door inner panel 1 having such a pull handle mounting boss 7 is formed as follows.

  That is, as shown in FIG. 2, the fixed handle 27, the movable mold 29 opposed to the fixed mold 27, and the pull handle mounting boss that is urged by a spring or the like so as to protrude toward the fixed mold 27 side. 7 and a pressing block 31 having a depression block 31a corresponding to the shape of the thick portion 23, and a fiber such as glass fiber from an injection machine in the cavity 35 with the molding die 33 closed. The filled thermoplastic resin R is injection filled. Thereafter, in the process in which the fiber-containing thermoplastic resin R is solidified in the cavity 35 of the molding die 33, the movable die 29 is moved backward in the direction in which the cavity volume is expanded, as indicated by a virtual line in FIG. That is, the movable die 29 is slightly separated from the fixed die 27, and the cavity volume corresponding to the door inner panel body 3 excluding the pull handle attaching boss 7 and the thick portion 23 is enlarged. The thermoplastic resin R containing fibers forms a surface layer as a skin layer (not shown) having a high resin density by quickly cooling the portion of the cavity 35 that contacts the molding surface due to the influence of mold temperature. On the other hand, the inner part of the fiber-containing thermoplastic resin R is hardly affected by the mold temperature and is in a gel state with high viscosity. Therefore, by expanding the cavity volume, the fiber that has been compressed with the resin pressure until then is released from the resin pressure and elastically restored. The elastic restoring force (spring back phenomenon) causes the fiber-containing thermoplastic resin R to expand. To do. As a result, the door inner panel 1 in which a large number of gaps A are formed inside the door inner panel main body 3 excluding the pull handle mounting boss 7 and the thick portion 23 is obtained, and the door inner panel 1 is reduced in weight. Can do.

  On the other hand, when the movable die 29 moves backward, the holding block 31 is biased toward the fixed die 27 and does not move. Therefore, the cavity volume corresponding to the pull handle mounting boss 7 and the thick portion 23 is increased during molding. The fibers in the thermoplastic resin R containing fibers are not expanded, and the elastic recovery is suppressed, and the thermoplastic resin R containing fibers flows out from the cavity 35 corresponding to the thick portion 23 into the cavity 35 whose micro amount is enlarged. However, it does not flow out of the cavity 35 corresponding to the pull handle mounting boss 7, and the formed pull handle mounting boss 7 becomes a solid solid without a gap A due to the outflow of the thermoplastic resin R containing fibers. Thus, the strength of the pull handle mounting boss 7 can be secured.

  Further, since the thick wall portion 23 exists between the door inner panel body 3 excluding the pull handle mounting boss 7 and the thick wall portion 23 and the base end of the pull handle mounting boss 7, Screw insertion of the pull handle mounting boss 7 by restricting the partial outflow of the thermoplastic resin R with fiber from the boss forming recess 31a associated with the expansion of the cavity volume corresponding to the door inner panel body 3 excluding the meat portion 23 The occurrence of cracks in the inner peripheral surface of the hole 7a is eliminated, and the strength of the boss 7 is improved. For example, when a tapping screw is screwed into the pull handle mounting boss 7, the screw handle is reliably secured and the pull handle mounting accuracy and mounting strength. Can be increased.

  Further, in the thick portion 23, a small amount of the thermoplastic resin R with fibers flows out from the concave portion 31b for forming the thick portion 23 into the enlarged cavity 35 when the movable mold 29 moves backward. Since the amount of outflow is very small, the strength of the thick portion 23 hardly decreases, and the strength around the base portion of the boss 7 can be further increased by the thick portion 23.

  FIG. 3 is an enlarged view of the pull handle mounting boss 7 of the door inner panel 1 according to the second embodiment. In the second embodiment, the thick portion 23 in the first embodiment is not provided, and instead, a plurality of pieces extending along the hole center line direction on the inner peripheral surface of the screw insertion hole 7a of the pull handle mounting boss 7. (Four) protrusions 37 are integrally provided with a gap in the circumferential direction.

  In other words, in the second embodiment, the pull handle mounting boss 7 is attached to the door inner panel body 3 excluding the pull handle mounting boss 7 in the course of solidification of the fiber-filled thermoplastic resin injected and filled into the cavity of the mold. The cavity volume corresponding to the door inner panel main body 3 to be removed is expanded and the thermoplastic resin containing fibers is expanded by the elastic restoring force of the fibers, thereby forming a large number of voids A therein, as in the first embodiment. The inner panel 1 can be reduced in weight.

  Further, the pull handle mounting boss 7 can be made a solid solid with no gap A without increasing the cavity volume corresponding to the pull handle mounting boss 7 at the time of molding, and the strength of the pull handle mounting boss 7 can be secured. .

  Furthermore, since there are a plurality (four) of protrusions 37 on the inner peripheral surface of the screw insertion hole 7a of the pull handle mounting boss 7, the inner surface 7a of the screw insertion hole and the molding die (pressing block 31 in FIG. 2). ) To increase the cavity volume corresponding to the door inner panel body 3 excluding the pull handle mounting boss 7 and the fiber from the boss forming recess to the fiber. Even if a part of the entering thermoplastic resin flows out, the crack generated on the inner peripheral surface of the screw insertion hole 7a of the pull handle mounting boss 7 is difficult and intermittent in the protrusion 37, and the protrusion 37 When the tapping screw is screwed in while securing the strength, this screwing is ensured, and the pull handle mounting accuracy and mounting strength can be increased.

  FIG. 5 is an enlarged view of the speaker housing portion 9 of the door inner panel 1 according to the third embodiment, and FIG. 4A is an enlarged view of the speaker mounting boss 13 formed integrally with the flange portion 11 of the speaker housing portion 9. Show. In the third embodiment, the speaker housing portion 9 includes a cylindrical peripheral wall 9b and a bottom wall 9c, and a through hole 9a is formed in the bottom wall 9c. On the other hand, the screw insertion hole 13a formed integrally with the speaker mounting boss 13 has a bottom, and a thick portion 23 is formed integrally with the bottom of the screw insertion hole 13a. A reinforcing rib 25 is integrally formed on the outer surface of the speaker mounting boss 13. A large number of gaps A are formed inside the door inner panel body 3 and the bottom wall 9 c of the speaker housing 9. On the other hand, the speaker mounting boss 13, the thick wall portion 23, the flange portion 11, and the peripheral wall 9 b of the speaker housing portion 9 are solid solids having no gap A.

  That is, in the third embodiment, in the process in which the fiber-filled thermoplastic resin injected and filled in the cavity of the molding die is solidified on the door inner panel body 3 and the bottom wall 9c of the speaker housing portion 9, the cavity volume corresponding to them is solidified. A large number of voids A are formed in the interior by expanding the thermoplastic resin containing fibers with the elastic restoring force of the fibers, and the door inner panel 1 can be reduced in weight as in the first embodiment. .

  Further, the speaker mounting boss 13, the thick wall portion 23, the flange portion 11, and the peripheral wall 9b of the speaker housing portion 9 are made solid solid without voids A without expanding the cavity volume corresponding to these, and their strength. Can be secured.

  Further, in the thick wall portion 23, as in the first embodiment, a small amount of thermoplastic resin containing fibers flows out from the concave portion for molding the thick wall portion 23 into the enlarged cavity during the movable backward movement. Since the outflow amount is very small, the strength of the thick portion 23 hardly decreases, and the strength around the base portion of the speaker mounting boss 13 can be further increased by the thick portion 23.

  In each of the above embodiments, a gap is formed inside the door inner panel body 3 by utilizing the fiber springback phenomenon. However, if a foaming agent is contained in the fiber-containing thermoplastic resin R, the springback Even when the restoring force of the fiber in the phenomenon is insufficient, the foaming force of the foaming agent is preferable because the restoring force of the fiber can be complemented and the void A can be reliably formed.

  Further, in each of the above embodiments, the case where the resin molded product is the door inner panel 1 of the automobile is shown, but it is a bonnet covering the engine room of the automobile, a ceiling material of the automobile, or a cylinder head cover of the engine. Furthermore, it can be applied to panels other than automobiles.

  The present invention is useful for a resin molded product having a component mounting boss having a screw insertion hole and having a large number of voids formed therein.

(A) is the II sectional view taken on the line of FIG. 6 of the boss for pull handle attachment of the door inner panel which concerns on Embodiment 1, (b) is a figure equivalent to FIG. 1 (a) of a prior art example. FIG. 3 is a molding process diagram showing a state in which a fiber-filled thermoplastic resin is injected and filled into a cavity of a mold in the first embodiment. (A) is a figure equivalent to Drawing 1 (a) of Embodiment 2, and (b) is a top view of Drawing 3 (a). (A) is a longitudinal cross-sectional view of the speaker mounting boss of the door inner panel according to Embodiment 3, and (b) is a view corresponding to FIG. FIG. 7 is a cross-sectional view taken along line VV in FIG. 6 of the speaker housing portion in the third embodiment. It is the perspective view which looked at the door inner panel from the vehicle interior side. It is the enlarged view which looked at the X section of FIG. 6 from the vehicle outer side.

Explanation of symbols

1 Door inner panel (resin molded product)
3 Door inner panel body (molded product body)
7 Pull handle mounting boss 13 Speaker mounting boss 7a, 13a Screw insertion hole 23 Thick part 33 Mold 35 Cavity 37 Projection part A Gap

Claims (2)

The component mounting boss having a screw insertion hole is a resin molded product formed integrally with the molded product body,
A thick part is integrally formed on the boss base end side,
The molded product body excluding the boss and thick part has a cavity volume corresponding to the molded product body excluding the boss and thick part in the process of solidifying the fiber-filled thermoplastic resin injected into the cavity of the mold. A large number of voids are formed inside by expanding and expanding the thermoplastic resin containing fibers with the elastic restoring force of the fibers,
A resin molded product, wherein the boss and the thick part are rigid solids without voids without expanding the cavity volume corresponding to the boss and the thick part during molding. The component mounting boss having a screw insertion hole is a resin molded product formed integrally with the molded product body,
On the inner peripheral surface of the screw insertion hole of the boss, a plurality of protrusions extending along the hole center line direction are integrally projected at intervals in the circumferential direction,
In the molded product body excluding the boss, the fiber-filled thermoplastic resin is expanded by expanding the cavity volume corresponding to the molded product body excluding the boss in the process of solidifying the injection-filled fiber-filled thermoplastic resin in the mold cavity. Many voids are formed inside by expanding the resin with the elastic restoring force of the fiber,
A resin molded product characterized in that the boss is a rigid solid without voids and does not enlarge the cavity volume corresponding to the boss during molding.

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