JP6156985B2 - Injection molding method and resin molded product - Google Patents

Injection molding method and resin molded product Download PDF

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JP6156985B2
JP6156985B2 JP2013136721A JP2013136721A JP6156985B2 JP 6156985 B2 JP6156985 B2 JP 6156985B2 JP 2013136721 A JP2013136721 A JP 2013136721A JP 2013136721 A JP2013136721 A JP 2013136721A JP 6156985 B2 JP6156985 B2 JP 6156985B2
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parting line
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JP2015009449A (en
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直也 池田
直也 池田
拓郎 東
拓郎 東
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Daihatsu Motor Co Ltd
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Description

本発明は、射出成形方法に関し、特に、異なる樹脂材料からなる第１部分及び第２部分を一体に有する樹脂成形品を同一金型内で成形する、いわゆる多色成形法に関する。   The present invention relates to an injection molding method, and more particularly to a so-called multicolor molding method in which a resin molded product integrally having a first portion and a second portion made of different resin materials is molded in the same mold.

例えば、自動車の内装品（インストルメントパネル等）は、異なる材質や色を有する複数種の樹脂材料を用いて、複数の部分を一体的に射出成形する、いわゆる多色成形法で製造することが知られている（例えば、下記の特許文献１参照）。具体的には、図８に示すように、上型１０１と下型１０２とを型締めしてキャビティを形成した状態で、スライド型１０３を上型１０１に当接させて第１のキャビティ１０４を区画する。この第１のキャビティ１０４に第１の樹脂材料を射出し、これを固化させて第１部分１１０を成形する（図９参照）。その後、スライド型１０３を降下させて上型１０１から離反させ、第２のキャビティ１０５を形成する（図１０参照）。この第２のキャビティ１０５に第２の樹脂材料を射出し、これを固化させて第２部分１２０を形成する（図１１参照）。以上により、第１部分１１０及び第２部分１２０を一体に有する樹脂成形品１３０が一つの射出成形金型内で成形される。   For example, automobile interior parts (instrument panels, etc.) can be manufactured by a so-called multicolor molding method in which a plurality of parts are integrally injection-molded using a plurality of types of resin materials having different materials and colors. It is known (for example, refer to Patent Document 1 below). Specifically, as shown in FIG. 8, in a state where the upper mold 101 and the lower mold 102 are clamped to form a cavity, the slide mold 103 is brought into contact with the upper mold 101 to form the first cavity 104. Partition. The first resin material is injected into the first cavity 104 and solidified to mold the first portion 110 (see FIG. 9). Thereafter, the slide mold 103 is lowered and separated from the upper mold 101 to form the second cavity 105 (see FIG. 10). The second resin material is injected into the second cavity 105 and solidified to form the second portion 120 (see FIG. 11). As described above, the resin molded product 130 integrally including the first portion 110 and the second portion 120 is molded in one injection mold.

特開平６−１９０８６５号公報JP-A-6-190865

上記のような多色成形を行うにあたっては、第１のキャビティ１０４に第１の樹脂材料を射出した後、スライド型１０３を降下させるタイミングが非常に重要となる。スライド型１０３を降下させるタイミングが早すぎると、第１部分１１０の端部が内部まで完全に硬化していない状態で、第２のキャビティ１０５に第２の樹脂材料が射出される（図１２参照）。この場合、第２の樹脂材料の射出圧により、第１部分１１０の未硬化部１１１が変形し、第１部分１１０と上型１０１との間に第２の樹脂材料が入り込み（図１２の矢印参照）、第１部分１１０と第２部分１２０との境界線（いわゆる見切り線）が不明瞭となる恐れがある。   In performing multicolor molding as described above, the timing of lowering the slide mold 103 after injecting the first resin material into the first cavity 104 is very important. If the timing of lowering the slide mold 103 is too early, the second resin material is injected into the second cavity 105 in a state where the end of the first portion 110 is not completely cured to the inside (see FIG. 12). ). In this case, the uncured portion 111 of the first portion 110 is deformed by the injection pressure of the second resin material, and the second resin material enters between the first portion 110 and the upper mold 101 (the arrow in FIG. 12). The boundary line (so-called parting line) between the first part 110 and the second part 120 may become unclear.

従って、スライド型１０３は、第１部分１１０の端部が内部まで完全に硬化してから降下させる必要がある。しかし、この場合、第１部分１１０の硬化を待つ時間が必要となってタクトタイムが長くなる。また、第１部分１１０の硬化範囲が広がりすぎると、第２の樹脂材料の射出圧により、第１部分１１０の意匠面（図中上面）のうち、スライド型１０３と下型１０２との境界の上方（図１０のＡ部）に白化が生じる恐れがある。   Therefore, the slide mold 103 needs to be lowered after the end portion of the first portion 110 is completely cured to the inside. However, in this case, it is necessary to wait for the first portion 110 to harden, and the tact time becomes long. Further, if the curing range of the first part 110 is excessively widened, the boundary between the slide mold 103 and the lower mold 102 in the design surface (upper surface in the drawing) of the first part 110 is caused by the injection pressure of the second resin material. There is a possibility that whitening may occur in the upper part (A portion in FIG. 10).

以上の点をまとめると、第１部分１１０の端部が内部まで完全に硬化した後で、且つ、白化が生じるほど硬化範囲が広くなりすぎないタイミングで、スライド型１０３を降下させる必要がある。しかし、このようなタイミングを見つけることは現実的には極めて困難であるため、実際には、ユーザの目に留まりやすい見切り線の不明瞭を回避するために、スライド型１０３の降下を遅めに設定し、若干の白化の発生を犠牲にしている。   In summary, the slide mold 103 needs to be lowered after the end portion of the first portion 110 is completely cured to the inside and at a timing at which the curing range does not become so wide that whitening occurs. However, in reality, it is extremely difficult to find such a timing. In practice, in order to avoid obscuration of the parting line that is easily noticed by the user, the lowering of the slide mold 103 is delayed. Set at the expense of some whitening.

以上のような事情から、本発明が解決すべき技術的課題は、多色成形を行うにあたり、見切り線の不明瞭化、及び白化の発生の双方を防止することにある。   In view of the above circumstances, the technical problem to be solved by the present invention is to prevent both the obscuration of parting lines and the occurrence of whitening when performing multicolor molding.

前記課題を解決するために、本発明は、意匠面を成形する一方の金型と、裏面を成形する他方の金型と、両金型で形成されるキャビティを区画するスライド型とを備えた射出成形金型を用いて、異なる樹脂材料からなる第１部分及び第２部分を一体に有する樹脂成形品を成形するための方法であって、前記スライド型を前記一方の金型に当接させて、前記一方の金型、前記他方の金型、及び前記スライド型で第１キャビティを形成し、該第１キャビティに第１の樹脂材料を射出して前記第１部分を成形する工程と、前記スライド型を前記一方の金型から離反させて、前記一方の金型、前記他方の金型、前記スライド型、及び前記第１部分で第２キャビティを形成し、該第２キャビティに第２の樹脂材料を射出して前記第２部分を成形する工程とを有し、前記第１部分と前記第２部分の見切り線の延在方向と直交する断面において、前記第１キャビティの前記見切り線側の端部が、先端へ向けて厚さを徐々に薄くした先細り形状を成すことを特徴とするものである。   In order to solve the above-mentioned problems, the present invention includes one mold for molding a design surface, the other mold for molding a back surface, and a slide mold for defining a cavity formed by both molds. A method for molding a resin molded product integrally having a first part and a second part made of different resin materials using an injection mold, wherein the slide mold is brought into contact with the one mold. Forming a first cavity with the one mold, the other mold, and the slide mold, and injecting a first resin material into the first cavity to mold the first portion; The slide mold is separated from the one mold to form a second cavity in the one mold, the other mold, the slide mold, and the first portion, and a second cavity is formed in the second cavity. A step of injecting the resin material and molding the second part In the cross section orthogonal to the extending direction of the parting line of the first part and the second part, the end part on the parting line side of the first cavity gradually decreases in thickness toward the tip. It is characterized by having a tapered shape.

このように、第１キャビティの見切り線側の端部を先細り形状とすることで、第１部分の端部を内部まで完全に早期に硬化させることができる。これにより、スライド型を一方の金型から早期に離反させることが許容されるため、見切り線の不明瞭の防止、及び、白化の発生の双方を防止できるような、スライド型のスライドのタイミングの設定が容易化される。   In this way, by forming the end portion on the parting line side of the first cavity into a tapered shape, the end portion of the first portion can be completely cured to the inside at an early stage. As a result, the slide mold is allowed to be separated from one mold at an early stage, so that the slide mold slide timing can be prevented so that both the obscure line and the whitening can be prevented. Setting is facilitated.

上記のように、第１部分の見切り線側の端部を先細り形状とすると、この端部の強度（剛性）が低くなるため、第２キャビティに射出された樹脂の圧力により端部が変形して、端部と一方の金型との間に第２の樹脂材料が入り込んで見切り線が不明瞭となる恐れがある。そこで、第１部分の見切り線側の端部を裏面側へ向けて曲げれば、この端部が射出圧により変形しにくくなるため、見切り線の不明瞭化をより確実に防止できる。   As described above, when the end portion on the parting line side of the first portion is tapered, the strength (rigidity) of this end portion is reduced, and therefore the end portion is deformed by the pressure of the resin injected into the second cavity. Then, the second resin material may enter between the end portion and one mold, and the parting line may become unclear. Therefore, if the end portion on the parting line side of the first portion is bent toward the back surface side, this end part is not easily deformed by the injection pressure, so that the parting line can be more reliably prevented from being obscured.

ところで、二色成形法で形成された樹脂成形品の意匠面には、デザイン上の観点から、見切り線の近傍に、他の領域よりも曲率半径の小さい小円弧部を設ける場合がある。この場合、前記第１キャビティの成形面に、見切り線と直交する断面における曲率半径が相対的に大きい大円弧部と、大円弧部の見切り線側に隣接し、上記の断面における曲率半径が相対的に小さい小円弧部とを設け、第１キャビティにおけるスライド型と一方の金型との境界を、小円弧部の裏面側に配することが好ましい。これにより、第１部分の硬化範囲が広がりすぎて、第２の樹脂材料の射出圧により第１部分の意匠面の上記境界付近に白化が生じた場合でも、その白化を小円弧部に発生させることができるため、白化が目立たなくなる。このため、スライド型を一方の金型から離反させるタイミングを遅らせることが許容されるため、見切り線の不明瞭の防止、及び、白化の発生の双方を防止できるような、スライド型のスライドのタイミングの設定がさらに容易化される。   By the way, on the design surface of the resin molded product formed by the two-color molding method, a small arc portion having a smaller radius of curvature than other regions may be provided near the parting line from the viewpoint of design. In this case, the molding surface of the first cavity is adjacent to the large arc portion having a relatively large curvature radius in the cross section perpendicular to the parting line and the parting line side of the large arc part, and the curvature radius in the cross section is relatively Preferably, a small arc portion is provided, and the boundary between the slide mold and the one mold in the first cavity is disposed on the back side of the small arc portion. As a result, even when the curing range of the first part is excessively widened and whitening occurs near the boundary of the design surface of the first part due to the injection pressure of the second resin material, the whitening occurs in the small arc portion. Whitening is less noticeable. For this reason, since it is allowed to delay the timing at which the slide mold is separated from one mold, the slide mold slide timing that can prevent both obscure parting lines and whitening can be prevented. Is further facilitated.

上記の射出成形方法によれば、第１部分を射出成形した後、同一金型内で第２部分を射出成形することにより、異なる樹脂材料からなる前記第１部分と前記第２部分を一体に有する樹脂成形品であって、前記第１部分と前記第２部分との見切り線の延在方向と直交する断面において、前記第１部分の前記見切り線側の端部が、先端へ向けて厚さを徐々に薄くした先細り形状を成すことを特徴とする樹脂成形品が得られる。   According to the above injection molding method, after the first part is injection-molded, the second part is injection-molded in the same mold, thereby integrating the first part and the second part made of different resin materials. In the cross section perpendicular to the extending direction of the parting line between the first part and the second part, the end part on the parting line side of the first part has a thickness toward the tip. A resin molded product characterized by having a tapered shape with a gradually reduced thickness is obtained.

以上のように、本発明によれば、多色成形を行うにあたり、見切り線の不明瞭化、及び、白化の発生の双方を防止することが可能となる。   As described above, according to the present invention, it is possible to prevent both the obscuration of parting lines and the occurrence of whitening when performing multicolor molding.

樹脂成形品（インストルメントパネル）の斜視図である。It is a perspective view of a resin molded product (instrument panel). 上記樹脂成形品の断面図である。It is sectional drawing of the said resin molded product. 上記樹脂成形品の射出成形金型の断面図である（第１キャビティ形成）。It is sectional drawing of the injection mold of the said resin molded product (1st cavity formation). 上記樹脂成形品の射出成形金型の断面図である（第１部分成形）。It is sectional drawing of the injection mold of the said resin molded product (1st partial molding). 上記樹脂成形品の射出成形金型の断面図である（第２キャビティ形成）。It is sectional drawing of the injection mold of the said resin molded product (2nd cavity formation). 上記樹脂成形品の射出成形金型の断面図である（第２部分成形）。It is sectional drawing of the injection mold of the said resin molded product (2nd partial molding). 他の実施形態に係る射出成形金型の断面図である。It is sectional drawing of the injection mold which concerns on other embodiment. 従来の射出成形金型の断面図である（第１キャビティ形成）。It is sectional drawing of the conventional injection molding die (1st cavity formation). 従来の射出成形金型の断面図である（第１部分成形）。It is sectional drawing of the conventional injection mold (1st partial shaping | molding). 従来の射出成形金型の断面図である（第２キャビティ形成）。It is sectional drawing of the conventional injection molding die (2nd cavity formation). 従来の射出成形金型の断面図である（第２部分成形）。It is sectional drawing of the conventional injection mold (2nd partial shaping | molding). 図１０の拡大図である。It is an enlarged view of FIG.

図１に示す樹脂成形品１は、自動車のインストルメントパネルであり、第１部分としての上面部２と、第２部分としての正面部３とを一体に有する。上面部２及び正面部３は、異なる樹脂材料で形成される。樹脂成形品１の意匠面（搭乗者から見える面）には、上面部２と正面部３との境界線（見切り線４）が設けられる。図２は、樹脂成形品１の見切り線４に垂直な断面であり、上面部２及び正面部３の図中上側の面が意匠面２ａ，３ａである。上面部２及び正面部３の端部同士は重ね合わせられ、図示例では、上面部２の裏面側（図中下側）に正面部３が配される。上面部２と正面部３の重合部の両側において、上面部２の意匠面２ａは正面部３の意匠面３ａよりも図中上方に位置し、上面部２の裏面２ｂは正面部３の裏面３ｂよりも図中上方に位置している。   A resin molded product 1 shown in FIG. 1 is an automobile instrument panel, and integrally includes an upper surface portion 2 as a first portion and a front portion 3 as a second portion. The upper surface portion 2 and the front surface portion 3 are formed of different resin materials. A boundary surface (parting line 4) between the upper surface portion 2 and the front surface portion 3 is provided on the design surface (surface visible to the passenger) of the resin molded product 1. FIG. 2 is a cross section perpendicular to the parting line 4 of the resin molded product 1, and the upper surfaces of the upper surface portion 2 and the front surface portion 3 in the drawing are the design surfaces 2a and 3a. The end portions of the upper surface portion 2 and the front surface portion 3 are overlapped, and in the illustrated example, the front surface portion 3 is disposed on the back surface side (lower side in the drawing) of the upper surface portion 2. On both sides of the overlapping portion of the upper surface portion 2 and the front surface portion 3, the design surface 2a of the upper surface portion 2 is located above the design surface 3a of the front surface portion 3 in the drawing, and the back surface 2b of the upper surface portion 2 is the back surface of the front surface portion 3. It is located in the upper part of the figure than 3b.

図３は、上記の樹脂成形品１を成形する射出成形金型１０であり、上型２０と、下型３０と、スライド型４０とを備える。図示例では、上型２０が固定型であり、下型３０が図中上下方向にスライドする可動型である。スライド型４０は、下型３０に対して図中上下方向にスライド可能とされる。   FIG. 3 shows an injection mold 10 for molding the resin molded product 1, and includes an upper mold 20, a lower mold 30, and a slide mold 40. In the illustrated example, the upper mold 20 is a fixed mold, and the lower mold 30 is a movable mold that slides in the vertical direction in the drawing. The slide mold 40 is slidable in the vertical direction in the figure with respect to the lower mold 30.

上型２０は、上面部２の意匠面２ａを成形する第１成形面２１と、正面部３の意匠面３ａを成形する第２成形面２２と、第１成形面２１と第２成形面２２との間に設けられた当接部２３とを有する。第１成形面２１の見切り線側（図中左側）の端部には、他の領域よりも曲率半径が小さい小円弧部２１ａが設けられる。本実施形態では、第１成形面２１に、曲率半径が相対的に大きい大円弧部２１ｂと、大円弧部２１ｂの見切り線側に隣接して設けられ、曲率半径が相対的に小さい小円弧部２１ａと、小円弧部２１ａのさらに見切り線側に隣接して設けられた直線部２１ｃとが設けられる。図示例では、大円弧部２１ｂを平面（曲率０）で示している。大円弧部２１ｂと小円弧部２１ａ、及び小円弧部２１ａと直線部２１ｃは、それぞれ滑らかに連続している。小円弧部２１ａと大円弧部２１ｂとの境界には、変曲点２１ｄが設けられる。直線部２１ｃは、樹脂成形品１の離型を容易化するために、スライド型４０のスライド方向（図中上下方向）に対して若干傾斜しており、その傾斜角αは例えば２°以上（図示例では５°）に設定される。第１成形面２１の大円弧部２１ｂは、第２成形面２２よりも図中上方に位置している。当接部２３は、第２成形面２２よりも図中下方に突出している。   The upper mold 20 includes a first molding surface 21 that molds the design surface 2 a of the upper surface portion 2, a second molding surface 22 that molds the design surface 3 a of the front surface portion 3, and the first molding surface 21 and the second molding surface 22. And an abutting portion 23 provided therebetween. A small arc portion 21a having a smaller radius of curvature than the other regions is provided at the end of the first molding surface 21 on the parting line side (left side in the drawing). In the present embodiment, the first forming surface 21 is provided with a large arc portion 21b having a relatively large radius of curvature and a small arc portion having a relatively small radius of curvature provided adjacent to the parting line side of the large arc portion 21b. 21 a and a straight line portion 21 c provided adjacent to the parting line side of the small arc portion 21 a are provided. In the example of illustration, the large circular arc part 21b is shown by the plane (curvature 0). The large arc portion 21b and the small arc portion 21a, and the small arc portion 21a and the straight portion 21c are smoothly continuous. An inflection point 21d is provided at the boundary between the small arc portion 21a and the large arc portion 21b. The straight portion 21c is slightly inclined with respect to the sliding direction (vertical direction in the drawing) of the slide mold 40 in order to facilitate the release of the resin molded product 1, and the inclination angle α is, for example, 2 ° or more ( In the illustrated example, it is set to 5 °. The large circular arc portion 21b of the first molding surface 21 is located above the second molding surface 22 in the figure. The contact portion 23 protrudes downward in the drawing from the second molding surface 22.

下型３０は、上面部２の裏面２ｂを成形する第３成形面３１と、正面部３の裏面３ｂを成形する第４成形面３２と、第３成形面３１と第４成形面３２との間に設けられ、スライド型４０を収容する孔３３とを有する。第３成形面３１は第４成形面３２よりも図中上方に位置している。   The lower mold 30 includes a third molding surface 31 that molds the back surface 2 b of the upper surface portion 2, a fourth molding surface 32 that molds the back surface 3 b of the front surface portion 3, and the third molding surface 31 and the fourth molding surface 32. And a hole 33 for receiving the slide mold 40. The third molding surface 31 is located above the fourth molding surface 32 in the drawing.

スライド型４０は、下型３０の孔３３の内部に配され、図中実線で示す上端位置と、図中鎖線で示す下端位置との間で上下方向にスライド可能とされる。スライド型４０は、上面４１に、平坦面４１ａ，４１ｂとこれらの間に設けられた傾斜面４１ｃとを有する。図中左側の平坦面４１ａは、スライド型４０を下端位置に配したときに、下型３０の第４成形面３２と連続する。図中右側の平坦面４１ｂは、左側の平坦面４１ａよりも図中上側に配され、スライド型４０を上端位置に配したときに、下型３０の第３成形面３１と連続する。スライド型４０のスライド方向に対する傾斜面４１ｃの傾斜角度βは、傾斜面４１ｃで成形される正面部３の傾斜部３ｃの肉厚を確保するために、例えば３０°以上（図示例では４５°）に設定される。   The slide mold 40 is disposed inside the hole 33 of the lower mold 30 and is slidable in the vertical direction between an upper end position indicated by a solid line in the figure and a lower end position indicated by a chain line in the figure. The slide mold 40 has flat surfaces 41 a and 41 b and an inclined surface 41 c provided therebetween on the upper surface 41. The left flat surface 41a in the drawing is continuous with the fourth molding surface 32 of the lower mold 30 when the slide mold 40 is disposed at the lower end position. The right flat surface 41b in the drawing is arranged on the upper side in the drawing with respect to the left flat surface 41a, and is continuous with the third molding surface 31 of the lower die 30 when the slide die 40 is arranged at the upper end position. The inclination angle β of the inclined surface 41c with respect to the sliding direction of the slide mold 40 is, for example, 30 ° or more (45 ° in the illustrated example) in order to ensure the thickness of the inclined portion 3c of the front portion 3 formed by the inclined surface 41c. Set to

以下、上記の射出成形金型１０を用いた射出成形方法の手順を説明する。   Hereinafter, the procedure of the injection molding method using the injection mold 10 will be described.

まず、図３に示すように、上型２０と下型３０を型締めした状態でスライド型４０を上昇させて、スライド型４０の上面４１を上型２０の当接部２３に当接させる。これにより、上型２０と下型３０とで形成されるキャビティがスライド型４０により区画され、上型２０の第１成形面２１、下型３０の第３成形面３１、及びスライド型４０の上面４１の平坦面４１ｂ及び傾斜面４１ｃで囲まれた第１キャビティ５０が形成される。   First, as shown in FIG. 3, the slide mold 40 is raised while the upper mold 20 and the lower mold 30 are clamped, and the upper surface 41 of the slide mold 40 is brought into contact with the contact portion 23 of the upper mold 20. Thereby, the cavity formed by the upper mold 20 and the lower mold 30 is partitioned by the slide mold 40, and the first molding surface 21 of the upper mold 20, the third molding surface 31 of the lower mold 30, and the upper surface of the slide mold 40. A first cavity 50 surrounded by the flat surface 41b and the inclined surface 41c of 41 is formed.

第１キャビティ６０の見切り線側（図中左側）の端部５１は、先端へ向けて厚さを徐々に薄くした先細り形状を成している。図示例では、第１キャビティ６０の端部５１が、見切り線側へ向けて裏面側（図中下方）に変位した成形面の間、具体的には、上型２０の第１成形面２１の直線部２１ｃ及び小円弧部２１ａと、スライド型４０の上面４１の傾斜面４１ｃとの間に形成される。第１キャビティ５０の端部５１の先端の角度θ（図示例では、直線部２１ｃと傾斜面４１ｃとの間の角度θ）が大きすぎると、端部５１の肉厚が過剰となり、端部５１に満たされた樹脂を早期に硬化させる効果（詳細は後述する）が得られないため、端部５１の先端の角度θは６０°以下、好ましくは４５°以下とされる。また、端部５１の先端の角度θが小さすぎると、端部５１の肉厚が不足し、第２の樹脂材料の射出圧（詳細は後述する）で変形しやすくなるため、角度θは２０°以上、好ましくは３０°以上とされる。   The end portion 51 on the parting line side (left side in the drawing) of the first cavity 60 has a tapered shape in which the thickness is gradually reduced toward the tip. In the illustrated example, the end portion 51 of the first cavity 60 is between the molding surfaces displaced toward the parting line side toward the back surface side (downward in the drawing), specifically, the first molding surface 21 of the upper mold 20. It is formed between the straight portion 21 c and the small arc portion 21 a and the inclined surface 41 c of the upper surface 41 of the slide mold 40. If the angle θ of the tip of the end 51 of the first cavity 50 (in the example shown, the angle θ between the straight portion 21c and the inclined surface 41c) is too large, the thickness of the end 51 becomes excessive, and the end 51 Since the effect of curing the resin filled in the above at an early stage (details will be described later) cannot be obtained, the angle θ of the tip of the end 51 is 60 ° or less, preferably 45 ° or less. Further, if the angle θ of the tip of the end 51 is too small, the thickness of the end 51 is insufficient, and deformation is easily caused by the injection pressure of the second resin material (details will be described later). More than 30 °, preferably more than 30 °.

そして、図４に示すように、第１キャビティ５０に第１の樹脂材料を射出し、上面部２を成形する。具体的には、第１キャビティ５０に射出された第１の樹脂材料が、金型に接触して冷却されることにより硬化する。このとき、第１キャビティ５０の端部５１が先細り形状を成していることで、この端部５１に満たされた第１の樹脂材料（すなわち、上面部２の端部２ｃ）を、内部まで完全に早期に硬化させることができる。   Then, as shown in FIG. 4, the first resin material is injected into the first cavity 50 to mold the upper surface portion 2. Specifically, the first resin material injected into the first cavity 50 is cured by contacting the mold and being cooled. At this time, since the end portion 51 of the first cavity 50 has a tapered shape, the first resin material filled in the end portion 51 (that is, the end portion 2c of the upper surface portion 2) is brought to the inside. It can be cured completely early.

その後、図５に示すように、スライド型４０を降下させて上型２０から離反させ、第２キャビティ６０を形成する。第２キャビティ６０は、上型２０の第２成形面２２及び当接部２３と、下型３０の第４成形面３２と、スライド型４０の上面４１と、上面部２の裏面２ｂとで囲まれている。このとき、スライド型４０の降下は、（ｉ）上面部２の端部２ｃが内部まで完全に硬化した後であって、且つ、（ｉｉ）上面部２のうち、第１キャビティ５０におけるスライド型４０の上面４１と下型３０の第３成形面３１との境界Ｐ（図４参照）付近が完全に硬化する前のタイミングで行う。従来、上記（ｉ）及び（ｉｉ）を両立させるタイミングを設定することは困難であったが、本発明では、上記のように第１キャビティ５０の端部５１を先細り形状とすることで、この部分に満たされた樹脂材料を早期に硬化させることができるため、上記（ｉ）のタイミングを早期化することが許容され、これにより上記（ｉ）及び（ｉｉ）を両立させるタイミングの設定が容易化される。尚、上記（ｉｉ）に示すように、上面部２の一部が完全に硬化していない状態でスライド型４０を降下させることで、上面部２に加わる射出圧により、上面部２の裏面２ｂのうち、完全に硬化した端部５１を除く領域が下方に若干膨らむ（図５に点線で誇張して示す）。   Thereafter, as shown in FIG. 5, the slide mold 40 is lowered and separated from the upper mold 20 to form the second cavity 60. The second cavity 60 is surrounded by the second molding surface 22 and the contact portion 23 of the upper mold 20, the fourth molding surface 32 of the lower mold 30, the upper surface 41 of the slide mold 40, and the back surface 2 b of the upper surface portion 2. It is. At this time, the slide mold 40 is lowered (i) after the end 2c of the upper surface portion 2 is completely cured to the inside, and (ii) the slide mold in the first cavity 50 of the upper surface portion 2. This is performed at a timing before the vicinity of the boundary P (see FIG. 4) between the upper surface 41 of 40 and the third molding surface 31 of the lower mold 30 is completely cured. Conventionally, it has been difficult to set the timing for making the above (i) and (ii) compatible, but in the present invention, the end 51 of the first cavity 50 is tapered as described above. Since the resin material filled in the portion can be cured at an early stage, it is allowed to advance the timing of the above (i), thereby easily setting the timing for making the above (i) and (ii) compatible. It becomes. As shown in the above (ii), the back surface 2b of the upper surface portion 2 is lowered by the injection pressure applied to the upper surface portion 2 by lowering the slide die 40 in a state where a part of the upper surface portion 2 is not completely cured. Among these, the region excluding the completely hardened end portion 51 slightly swells downward (shown exaggerated by dotted lines in FIG. 5).

そして、図６に示すように、第２キャビティ５０に第２の樹脂材料を射出する。このとき、上面部２の端部２ｃは内部まで完全に硬化しているため、第２の樹脂材料の射出圧による変形が防止される。従って、上面部２の端部２ｃと上型２０の第１成形面２１（特に直線部２１ｃ）との間に第２の樹脂材料が入り込む事態が回避され、上面部２と正面部３との意匠面における境界線（見切り線４）の不明瞭化を防止できる。特に、本実施形態では、上面部２の端部２ｃが裏面側（図中下側）に曲がっていることで、第２の樹脂材料の射出圧による端部２ｃの変形を確実に防止し、端部２ｃと第１成形面２１との間への第２の樹脂材料の侵入を確実に防止できる。また、上面部２のうち、スライド型４０の上面４１と下型３０の第３成形面３１との境界Ｐ付近は完全には硬化していないため、第２の樹脂材料の射出圧により上面部２の意匠面２ａ、特に境界Ｐの上方部分に白化が生じる事態を防止できる。その後、正面部３が硬化することで、上面部２と正面部３とを一体に有する樹脂成形品１が完成する。   Then, as shown in FIG. 6, the second resin material is injected into the second cavity 50. At this time, since the end portion 2c of the upper surface portion 2 is completely cured to the inside, deformation due to the injection pressure of the second resin material is prevented. Therefore, the situation where the second resin material enters between the end 2c of the upper surface portion 2 and the first molding surface 21 (particularly the straight portion 21c) of the upper mold 20 is avoided, and the upper surface portion 2 and the front surface portion 3 Obfuscation of the boundary line (parting line 4) on the design surface can be prevented. In particular, in the present embodiment, the end 2c of the upper surface portion 2 is bent to the back side (lower side in the figure), thereby reliably preventing deformation of the end 2c due to the injection pressure of the second resin material, Intrusion of the second resin material between the end 2c and the first molding surface 21 can be reliably prevented. Further, in the upper surface portion 2, the vicinity of the boundary P between the upper surface 41 of the slide mold 40 and the third molding surface 31 of the lower mold 30 is not completely cured, so the upper surface portion is caused by the injection pressure of the second resin material. It is possible to prevent whitening of the second design surface 2a, particularly the upper portion of the boundary P. Thereafter, the front portion 3 is cured, whereby the resin molded product 1 having the upper surface portion 2 and the front portion 3 integrally is completed.

本発明は上記の実施形態に限られない。例えば、上記の実施形態では、図３に示すようにスライド型４０を上型２０に当接させて第１キャビティ５０を形成した状態で、スライド型４０の上面４１と下型３０の第３成形面３１との境界Ｐが、第１成形面２１の大円弧部２１ｂの裏面側（すなわち、変曲点２１ｄよりも図中右側）に配されているが、これに限られない。例えば図７に示す実施形態は、第１キャビティ５０を形成した状態で、スライド型４０の上面４１と下型３０の第３成形面３１との境界Ｐが、第１成形面２１の小円弧部２１ａの裏面側（すなわち、変曲点２１ｄよりも図中左側）に配されている。このように、白化が生じやすい境界Ｐを、曲率半径の小さい小円弧部２１ａの下方に配することで、万が一この部分に白化が生じても、大円弧部２１ｂに白化が生じた場合よりも白化を目立たなくすることができる。   The present invention is not limited to the above embodiment. For example, in the above embodiment, the third mold of the upper surface 41 of the slide mold 40 and the third mold 30 is formed in a state where the first cavity 50 is formed by bringing the slide mold 40 into contact with the upper mold 20 as shown in FIG. The boundary P with the surface 31 is arranged on the back surface side of the large arc portion 21b of the first molding surface 21 (that is, on the right side in the drawing with respect to the inflection point 21d), but is not limited thereto. For example, in the embodiment shown in FIG. 7, in a state where the first cavity 50 is formed, the boundary P between the upper surface 41 of the slide mold 40 and the third molding surface 31 of the lower mold 30 is a small arc portion of the first molding surface 21. It is arranged on the back side of 21a (that is, on the left side in the figure from the inflection point 21d). In this way, by arranging the boundary P that is likely to be whitened below the small arc portion 21a with a small radius of curvature, even if whitening occurs in this portion, it is more than when whitening occurs in the large arc portion 21b. Whitening can be made inconspicuous.

１ 樹脂成形品
２ 上面部（第１部分）
２ａ 意匠面
３ 正面部（第２部分）
３ａ 意匠面
４ 見切り線
１０ 射出成形金型
２０ 上型（一方の金型）
２１ 第１成形面
２１ａ 小円弧部
２１ｂ 大円弧部
２１ｃ 直線部
２１ｄ 変曲点
２２ 第２成形面
３０ 下型（他方の金型）
３１ 第３成形面
３２ 第４成形面
４０ スライド型
５０ 第１キャビティ
６０ 第２キャビティ 1 Resin molded product 2 Top surface (first part)
2a Design surface 3 Front part (second part)
3a Design surface 4 Parting line 10 Injection mold 20 Upper mold (one mold)
21 First molding surface 21a Small arc portion 21b Large arc portion 21c Linear portion 21d Inflection point 22 Second molding surface 30 Lower mold (other mold)
31 Third molding surface 32 Fourth molding surface 40 Slide mold 50 First cavity 60 Second cavity

Claims (2)

意匠面を成形する一方の金型と、裏面を成形する他方の金型と、両金型で形成されるキャビティを区画するスライド型とを備えた射出成形金型を用いて、異なる樹脂材料からなり、それぞれ意匠面が設けられた第１部分及び第２部分を一体に有する樹脂成形品を成形するための方法であって、
前記スライド型を前記一方の金型に当接させて、前記一方の金型、前記他方の金型、及び前記スライド型で第１キャビティを形成し、該第１キャビティに第１の樹脂材料を射出して前記第１部分を成形する工程と、前記スライド型を前記一方の金型から離反させて、前記一方の金型、前記他方の金型、前記スライド型、及び前記第１部分で第２キャビティを形成し、該第２キャビティに第２の樹脂材料を射出して前記第２部分を成形する工程とを有し、
前記第１部分と前記第２部分の見切り線の延在方向と直交する断面において、前記第１キャビティの前記見切り線側の端部が、先端へ向けて厚さを徐々に薄くした先細り形状を成し、且つ、裏面側へ曲がっていることを特徴とする射出成形方法。 By using an injection mold having one mold for molding the design surface, the other mold for molding the back surface, and a slide mold for defining a cavity formed by both molds, from different resin materials Do Ri, a first portion and a second portion design surface is respectively provided a method for molding a resin molded article having integral,
The slide mold is brought into contact with the one mold to form a first cavity with the one mold, the other mold, and the slide mold, and a first resin material is formed in the first cavity. A step of injecting and molding the first part; and separating the slide mold from the one mold, the first mold, the other mold, the slide mold, and the first part Forming two cavities, injecting a second resin material into the second cavities, and molding the second part,
In the cross section orthogonal to the extending direction of the parting line of the first part and the second part, the end part on the parting line side of the first cavity has a tapered shape in which the thickness is gradually reduced toward the tip. adult City, and an injection molding method, characterized in that bent to the back side. 第１部分を射出成形した後、同一金型内で第２部分を射出成形することにより、異なる樹脂材料からなり、それぞれ意匠面が設けられた前記第１部分と前記第２部分を一体に有する樹脂成形品であって、
前記第１部分と前記第２部分との見切り線の延在方向と直交する断面において、前記第１部分の前記見切り線側の端部が、先端へ向けて厚さを徐々に薄くした先細り形状を成し、且つ、裏面側へ曲がっていることを特徴とする樹脂成形品。 After the first portion was injection-molded by injection molding a second portion in the same mold, Varies depending Do a resin material, said first portion design surface is provided respectively to said second portion integrally A resin molded product having
In the cross section orthogonal to the extending direction of the parting line between the first part and the second part, the end part on the parting line side of the first part has a tapered shape in which the thickness is gradually reduced toward the tip. the formed to, and a resin molded article, characterized in that bent to the back side.
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JP7151028B2 (en) * 2018-09-25 2022-10-12 ダイハツ工業株式会社 Method for manufacturing resin molded member
JP7455636B2 (en) 2020-03-31 2024-03-26 ダイハツ工業株式会社 Multicolor molded product and method for manufacturing multicolor molded product

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