JP4890168B2 - Mold for RIM molding of resin molded product and RIM molding method - Google Patents

Description

  The present invention relates to a resin molded product such as an air bag cover that is mounted on a steering wheel of an automobile or the like and covers an airbag device, particularly a resin molded product for forming a skin layer on the surface of a core material for RIM molding. The present invention relates to a mold and a RIM molding method.

  Conventionally, this type of resin molded product, for example, automotive interior parts such as airbag covers, horn pads, headrests, armrests, steering wheels, etc. has no stickiness when touched by hand, and is strong due to interference with other members. In order to satisfy the requirements for stability of hardness and hardness, there is one constituted by laminating a film-like skin layer made of soft urethane on the surface of a resin core material.

  And in order to laminate | stack the said skin layer on a core material, the RIM shaping | molding method is employ | adopted widely.

The RIM molding method is for forming a skin layer for laminating a skin layer on the surface of the core material in the cavity by inserting a preformed core material into a cavity formed by an upper mold and a lower mold. A cavity portion is formed, and a liquid resin is introduced into the skin layer forming cavity portion from the gate portion so that the skin layer is laminated on the surface of the core material (Patent Documents 1 and 2). And 3)
Japanese Patent Laid-Open No. 5-261649. JP-A-6-99452. JP 2004-58564 A.

  According to the above-mentioned patent document, as shown in FIG. 9A, the cavity d is formed by the upper mold b and the lower mold c constituting the RIM mold a, and the cavity d is previously formed by injection molding or the like. By setting the core material e which has been molded, a cavity portion f for forming the skin layer is formed on the lower mold c side where the core material e does not exist in the cavity d, and then from the mixing head k A liquid resin h made of polyurethane resin or the like supplied with a predetermined introduction pressure through the runner m is applied to the gate part g formed over the upper mold b and the lower mold c as shown in FIG. 9-2. Furthermore, as shown in FIG. 9-3, by introducing the liquid resin h into the skin layer molding cavity portion f and filling the skin layer molding cavity portion, the surface of the core material e is introduced. To form a film-like skin layer Which was.

  However, according to the conventional method, when the liquid resin h is introduced into the gate portion g in the state shown in FIG. 9-2, the liquid resin h is introduced with a predetermined introduction pressure. Due to the introduction pressure, the core material e may be pressed in the introduction direction of the liquid resin h, and may be separated from the cavity forming surface i of the upper mold b, for example, to form the mold gap j.

  As a result, the liquid resin h wraps around the mold gap j, and the surface layer portion is formed from the end surface to the back surface side of the core material e, resulting in a defective product.

  Therefore, in view of such points, the present invention provides a resin molded product and a resin molded product RIM in which the surface layer portion is not formed up to the back surface side of the core material when the surface layer portion is laminated on the core material by the RIM core material. It aims at providing the shaping | molding die for shaping | molding, and the RIM shaping | molding method.

  In order to achieve the above-mentioned object, the RIM molding mold of the resin molded product according to the present invention is inserted into a cavity formed by a pre-molded core material into a cavity formed by an upper mold and a lower mold. Forming a skin layer molding cavity portion for laminating a skin layer on the surface of the core material, introducing a liquid resin from the gate portion into the skin layer molding cavity portion to the surface of the core material; A mold for RIM molding of a resin molded product in which an outer skin layer is laminated, wherein a dam portion protrudes from a gate facing portion of the core material facing the gate portion, and the dam portion is the gate portion. By receiving the introduction pressure of the liquid resin introduced more, the liquid resin is introduced into the skin layer molding cavity portion in a state where the core material is pressed against the cavity wall surface, and is applied to the surface of the core material. Characterized by being configured to form a skin layer.

  The present invention having such a configuration is introduced from the gate portion at the time of RIM molding of the surface layer portion because the dam portion protrudes from the gate facing portion facing the gate portion of the RIM mold in the outer peripheral portion of the core material. As a result, the introduction pressure of the liquid resin is exerted on the dam portion so that the core material is brought into close contact with the cavity wall surface, and the conventional mold gap j is not formed. The surface layer will not be formed up to the back of the core material, and the surface layer will also be formed in the dam, but if it is cut after molding, a molded resin product with high aesthetics will be formed. can do.

  Further, the RIM molding die of the resin molded product according to the present invention has a protruding portion formed on the outer peripheral portion of the core material other than the dam portion, and the protruding portion is formed by the upper die and the lower die. You may comprise so that the said liquid resin may be introduce | transduced into the said cavity layer shaping | molding cavity part in the state inserted | pinched, and a skin layer may be formed in the surface of the said core material.

  In the invention having such a configuration, the core material is securely fixed in the cavity by sandwiching the protrusion between the upper mold and the lower mold of the RIM mold when the surface layer portion is molded. It is possible to reliably prevent the occurrence of mold gaps due to the resin introduction pressure, and to provide a resin molded product with high aesthetics by cutting away the portion of the protrusion that does not have the surface layer on the tip side. can do.

  Further, in the RIM molding method of the resin molded product according to the present invention, the dam part protrudingly formed on the outer peripheral part of the core material is placed at the gate facing part where the gate part of the RIM molding die faces, At the time of RIM molding, the introduction pressure of the liquid resin introduced from the gate part is exerted on the dam part and works to bring the core material into close contact with the cavity wall surface, thereby forming a conventional mold gap j. As a result, the surface layer part will not be formed up to the back surface of the core material, and the surface layer part will also be formed in the dam part. It is possible to provide a resin molded product rich in.

  According to the present invention configured as described above, since the dam portion is formed to protrude from the gate facing portion of the outer peripheral portion of the core material facing the gate portion of the RIM mold, it is introduced from the gate portion during the RIM molding of the surface layer portion. The introduction pressure of the liquid resin thus applied is exerted on the dam part, so that the core material is brought into close contact with the cavity wall surface, and the conventional mold gap j is not formed, and as a result, The surface layer is no longer formed up to the back of the core material, and the surface layer is also formed in the dam, but if it is cut after molding, a resin molded product with high aesthetics is provided. can do.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of an airbag cover employing an embodiment according to the present invention, FIG. 2 is a perspective view of the airbag cover in a state of being released from the RIM mold, and FIG. 3 is shown in FIG. An explanatory view for cutting the gate portion equivalent portion and the dam portion formed at the time of molding in the airbag cover into the finished airbag cover shown in FIG. 1, FIG. 4-1 is shown in FIG. 2 shown in FIG. 2 is a cross-sectional view taken along line AA in FIG. 2 in a RIM mold for forming an airbag cover, FIG. 4-2 is a cross-sectional view of a main portion of the drawing in which liquid resin is introduced to the gate portion, and FIG. FIG. 5 is a cross-sectional view depicting a state in which the liquid resin has passed through the gate portion and is introduced into the skin layer forming cavity.

  First, an airbag cover, which is a resin molded product molded according to one embodiment of the present invention, will be described with reference to FIG.

  The airbag cover 1 is attached to a steering wheel (not shown) to cover the airbag device, and is a core material 2 formed by injection molding or the like using a resin having some rigidity such as TPO, TPU, or TPS. And a film-like skin layer 3 in which the surface facing the occupant side of the core material 2 is laminated and coated.

  The skin layer 3 is formed by laminating the core material 2 by RIM molding, which will be described later, and is made of a urethane-based resin such as polyurethane. In some cases, the skin layer 3 is laminated on the core material via an adhesive. In some cases. That is, when the core material 2 is TPO or TPS or the like, an adhesive is interposed, but when it is TPU or the like, the core material 2 is laminated on the core material 2 without an adhesive. The core member 2 includes a box-shaped airbag housing portion 2a that opens on the lower surface side, and an upper wall portion 2b that is integrally formed on the upper surface side of the airbag housing portion 2a. The skin layer 3 is laminated on the surface facing the occupant side of the upper wall portion 2b, and the skin layer 3 extends so as to cover the end surface of the upper wall portion 2b.

  The airbag cover 1 has, for example, a substantially trapezoidal shape when viewed from above, with the upper base 1a on the long side on the upper side and the lower base 1b on the short side on the lower side. Although mounted on the steering wheel, cut surfaces 2c and 3c are formed on the end surface of the core member 2 and the end surface of the skin layer 3 at the substantially central portion of the lower base 1b as shown by oblique lines. .

  The cut surface 2c is a surface obtained by cutting a dam portion previously formed on the core material 2 described later, and the cut surface 3c is cut by a dam portion described later on a terminal extension portion formed when the surface layer portion 3 is laminated. Surface.

  Next, referring to FIG. 2, the airbag cover remains released from the RIM mold described later, which is a state in which the skin layer 3 is laminated on the core material 2 before forming the cut surfaces 2c and 3c shown in FIG. 1 will be described.

  That is, the airbag cover 1 has a skin layer 3 laminated on the surface portion of the upper wall portion 2b of the core member 2, but the outer peripheral portion of the core member 2 has an outer periphery on the substantially central outer periphery of the lower base 1b. A dam portion 4 is formed so as to protrude in the direction. The dam portion 4 is integrally formed with the core material 2 at the same time when the core material 2 is previously formed by injection molding or the like, for example.

  On the upper surface side of the dam portion 4, a terminal extending portion 3 a of the skin layer 3 is laminated at the time of RIM molding of the skin layer 3 to be described later, and the RIM molding to be described later is formed on the outer end side of the terminal extending portion 3 a. Protrusions 5 formed by the gate portions of the mold are connected.

  Therefore, as shown in FIG. 3, the dam part 4 and the terminal extension part 3a on the core material 2 side are cut together with the gate part forming part 10b after the RIM molding to complete the airbag cover 1 shown in FIG. However, at this time, the cut surfaces 2c and 3c described above are formed by cutting the dam portion 4 and the terminal extension portion 3a.

  Next, the case where the unfinished airbag cover 1 shown in FIG. 2 is molded using the RIM mold shown in FIGS. 4-1 to 4-3 will be described.

  That is, the RIM mold 6 includes an upper mold 7 and a lower mold 8, and a cavity 9 is formed by the upper mold 7 and the lower mold 8.

  The cavity 9 is inserted between the core material 2 and the cavity forming surface 8-1 of the lower mold 8 by inserting the core material 2 molded in advance by injection molding or the like with the core material 2 brought close to the upper mold 7 side. The skin layer forming cavity 9a is formed as a space.

  Under the present circumstances, the dam part 4 formed in the core material 2 is arrange | positioned in the gate opposing part which opposes the thin gate part 10a which exists in the one end side of the gate part 10 formed in the upper mold | type 7 and the lower mold | type 8. The other end side of the gate portion 10 is connected to a runner 12 that introduces the liquid resin 11 led out from the mixing head 14 into the gate portion 10.

  In order to laminate the skin layer 3 on the core material 2 by the RIM molding using the RIM molding die 6 configured as described above, first, as shown in FIG. 4A, the upper layer 7 and the lower die 8 are formed. The core material 2 molded in advance is set in the cavity 9. As a result, the core material 2 is set in a state of being brought closer to the cavity molding surface 7-1 side of the upper die 7, and thereby, the cavity forming surface 8-of the lower die 8 in the cavity 9. The surface layer portion forming cavity 9 a is formed by 1 and the core material 2.

  And in this state, the dam part 4 of the core material 2 is also brought close to the upper mold 7 side of the gate part 10, and the thin gate part 10 a is formed on one end side of the gate part 10. become.

  Next, as shown in FIG. 4B, the liquid resin 11 composed by mixing the isocyanate component and the polyol component in the mixing head 14 passes through the runner 12 with a predetermined introduction pressure applied. Introduced into the gate unit 10.

  After the time when the liquid resin 11 reaches the thin gate portion 10a, the dam surface 4a facing the lower mold 8 side of the dam portion 4 becomes the cavity forming surface 7- of the upper mold 7 due to the introduction pressure of the liquid resin 11. The core material 2 is brought into close contact with the cavity forming surface 7-1 of the upper mold 7 by being pressed to the 1 side.

  From this state, the liquid resin 11 is further filled in the skin layer forming cavity 9a by introducing the liquid resin 11 from the gate portion 10 into the skin layer forming cavity 9a (FIG. 4). -3), the skin layer 3 is laminated on the surface of the lower base 1b of the core material 2.

  When the formed skin layer 3 is solidified and released from the RIM mold 6, the unfinished airbag cover 1 shown in FIG. 2 is molded.

  In such a configuration, since the dam portion 4 is formed to protrude from the gate facing portion that faces the gate portion 10 of the RIM mold 6 in the substantially central outer peripheral portion of the core material 2, when the RIM molding of the surface layer portion 3 is performed, from the gate portion 10. The introduction pressure of the introduced liquid resin 11 is exerted on the dam portion 4, and the core material 2 is pressed against the cavity forming surface 7-1 side of the upper mold 7 so as to be brought into close contact with the conventional dam part 4. Such a mold gap j is not formed, and as a result, the surface layer portion 3 is not formed up to the back surface side of the core material 2, and the terminal extension portion of the surface layer portion 3 is also formed in the dam portion 4. 3a is formed, but if the terminal extending portion 3a is cut after molding together with the protruding portion 5 formed by the gate portion 10, the air bag cover 1 as shown in FIG. To be able to provide That.

  FIG. 5 shows a second embodiment of the RIM mold 6 according to the present invention, and shows a modification of the cross-sectional shape of the gate portion 10 with respect to the above-described embodiment.

  That is, in the RIM mold 6 shown in FIG. 5, a convex curved portion 7a is formed on the lower die 8 side by forming an arc-shaped convex portion 7a on the upper die 7 side in the gate portion 10, and the liquid resin 11 is damped. After turning downward toward the lower mold 8 side of the part 4, it is then bent upward and the side facing the lower mold 8 in the dam part 4 is pushed up to the upper mold 7 side and acts to push up To do.

  With this configuration, in the process of laminating the surface layer portion 3 on the core material 2, the liquid resin 11 introduced from the runner 12 is led out to the skin layer forming cavity portion side while the introduction direction is bent in the gate portion 10. As a result of the bending, the dam portion 4 is pushed up more strongly on the upper mold 7 side, and the core material 2 is brought into close contact with the cavity forming surface 7-1 side of the upper mold 7. The prevention of the wraparound prevention to the back surface side of the core material 2 is achieved.

  FIG. 6 shows a third embodiment of the RIM mold according to the present invention.

  According to the RIM mold 6 shown in FIG. 6, the skin 3 is formed so that the end portion 3 a of the skin layer 3 is wound around the end of the core material 2 on the upper base 4 a side of the airbag cover 1. The layer forming cavity 9a is formed so as to continue from the end side of the core material 2 to a part of the back side.

  With such a configuration, the liquid resin 11 eventually wraps around the back side of the core member 2, but when it reaches the upper base 4 a side of the airbag cover 1, it is at a position far away from the gate portion 10. It is in a state where the pressure is greatly reduced from the introduction pressure, and it cannot work so as to generate a mold gap between the core material 2 and the cavity forming surface 7-1 of the upper mold 7, which is a conventional problem. Does not happen.

  Furthermore, FIG. 7 is a perspective view of the airbag cover in a state of being released from the RIM mold according to the fourth embodiment.

  According to FIG. 7, the outer peripheral portion of the upper wall portion 2 b of the core member 2 is connected to the dam portion 4 provided on the lower bottom side 1 b of the airbag cover 1 in the above-described embodiment, on the side portions 1 c side. The difference is that an extending protrusion 13 is formed.

  In the present embodiment, the protrusion 13 is formed narrower as it goes to the upper base 1a side of the airbag cover 1 and extends to the entire side 1c, but reaches the upper base 1a. You may terminate before doing.

  When the surface layer portion 3 is formed using the core material 11 having such a configuration, a RIM mold 6 as shown in FIG. 8 is used.

  That is, the RIM mold 6 is a liquid resin in the skin layer molding cavity 9a in a state where the protrusion 13 is sandwiched between the upper mold 7 and the lower mold 8 on the outer periphery of the skin layer molding cavity 9a. 11 is poured, the core material 2 is firmly set in the cavity 9, and the action of the dam part 4 is promoted.

  The protrusion 13 is formed so as to narrow toward the upper base 1a side of the airbag cover 1 when the liquid resin 11 reaches the upper base 4a side of the airbag cover 1. Since the position is far from 10, the pressure is greatly reduced from the introduction pressure so that a mold gap is formed between the core material 2 and the cavity forming surface 7-1 of the upper mold 7. In addition to being unable to work, after the surface layer portion 3 is laminated on the core material 2, the protruding portion 13 is cut so that the end surfaces of both are flush with each other, so that the amount of material is reduced.

  In addition, in the said embodiment, although the case where it applied about the airbag cover 1 was demonstrated as a resin molded product, it is not limited to this, For example, a horn pad, a headrest which are interior parts of a motor vehicle, The present invention can also be applied to resin molded products such as armrests and steering wheels.

  As described above, the present invention is introduced from the gate portion at the time of RIM molding of the surface layer portion because the dam portion protrudes from the gate facing portion facing the gate portion of the RIM molding die in the outer peripheral portion of the core material. The introduction pressure of the liquid resin is exerted on the dam portion, and the core material is brought into close contact with the cavity wall surface, so that the conventional mold gap j is not formed, and as a result, the core The surface layer part will not be formed to the back of the material, and the surface layer part will also be formed in the dam part, but if it is cut after molding, it will provide a resin molded product with high aesthetics RIM formation of resin molded products such as airbag covers that are mounted on steering wheels of automobiles and the like to cover airbag devices, especially resin molded products for forming a skin layer on the surface of the core material It is suitable for use mold and RIM molding method and the like.

It is a perspective view of the airbag cover which employ | adopted one embodiment which concerns on this invention. It is a perspective view of the airbag cover in the state still released from the RIM mold. FIG. 3 is an explanatory view for cutting a portion corresponding to a gate portion and a dam portion formed at the time of molding in the airbag cover shown in FIG. 2 to obtain a completed product airbag cover shown in FIG. 1. It is sectional drawing which follows the AA line of FIG. 2 in the RIM shaping | molding die for shape | molding the airbag cover shown in FIG. 2 shown in FIG. It is sectional drawing which similarly drawn the state which introduce | transduced liquid resin to the gate part. Similarly, it is sectional drawing which drawn the state by which liquid resin passed through the gate part and was introduce | transduced in the skin layer shaping | molding cavity. FIG. 4 is a cross-sectional view showing a second embodiment of the RIM mold according to the present invention and corresponding to FIG. 4-3. FIG. 9 is a cross-sectional view taken along line AA in FIG. 2, showing a third other embodiment of the RIM mold according to the present invention. It is a perspective view of the airbag cover which drawn the state with which it released from the RIM shaping | molding die by 4th Embodiment which concerns on this invention. 8 shows a RIM mold according to a fourth embodiment of the present invention, and is a cross-sectional view taken along the line BB of FIG. It is sectional drawing which drawn the conventional RIM shaping | molding die, and has shown the state which inserted the core material and formed the skin layer shaping | molding cavity. Similarly, a state in which the liquid resin is introduced to the gate portion is shown. Similarly, the liquid resin passes through the gate portion and is shown in the skin layer forming cavity.

Explanation of symbols

1 Airbag cover (resin molded product)
2 Core material 3 Skin layer 3a Terminal extension part 4 Dam part 6 RIM molding die 7 Upper mold 7-1 Cavity forming surface 8 Lower mold 8-1 Cavity forming surface 9 Cavity 9a Cavity part for skin layer molding 10 Gate part 11 Liquid resin 13 Protrusion part

Claims (3)

When a preformed core material is inserted into a cavity formed by an upper mold and a lower mold, a skin layer molding cavity for laminating a skin layer on the surface of the core material is formed in the cavity. A mold for RIM molding of a resin molded product in which a liquid resin is introduced from the gate portion into the skin layer molding cavity and the skin layer is laminated on the surface of the core material,
A dam portion is formed to project at a location facing the gate portion in the core material, and the dam portion receives the introduction pressure of the liquid resin introduced from the gate portion, whereby the core material is applied to the cavity wall surface. The RIM molding die, wherein the liquid resin is introduced into the skin layer molding cavity in the pressed state to form a skin layer on the surface of the core material.   A protrusion is formed on the outer peripheral portion of the core material other than the dam portion, and the liquid resin is applied to the skin layer forming cavity in a state where the protrusion is sandwiched between the upper mold and the lower mold. 2. The mold for RIM molding of a resin molded product according to claim 1, wherein the mold is introduced to form a skin layer on the surface of the core material. By inserting a preformed core material into the cavity of the RIM mold, a cavity layer molding cavity portion is formed in the cavity to be laminated on the surface of the core material, and the skin layer molding cavity A RIM molding method in which a liquid resin is introduced into the part from the gate part and a skin layer is laminated on the surface of the core material,
When the liquid resin is introduced from the gate portion into the skin layer forming cavity portion after the dam portion protruding from the core material is arranged at the gate portion of the RIM mold, the introduction pressure of the liquid resin is increased. The dam portion receives the pressure so that a skin layer is formed on the surface of the core material by the liquid resin in a state where the core material is pressed against the wall surface side of the cavity. RIM molding method for molded products.

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