JP6776000B2 - Manufacturing method of two-color molded products and two-color molded products - Google Patents

Description

The present invention relates to a two-color molded product.

Conventionally, as one method of injection molding, a technique for producing a two-color molded product by forming a primary molded product and then forming a secondary molded product around the primary molded product is known. The two-color molding technique is used, for example, when manufacturing a translucent cover for a lamp such as a vehicle headlamp (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-176974

By the way, in two-color molding, depending on the shape of the secondary molded product, if the molten resin flows into the cavity formed by the mold, the gas existing in the mold cannot be discharged well to the outside of the mold. It may remain as bubbles. As a result, a part of the secondary molded product is deficient in meat, or the trapped air bubbles are adiabatically compressed to a high temperature, resulting in a so-called gas burn, which is a poor appearance.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for reducing appearance defects in a two-color molded product.

In order to solve the above problems, the two-color molded product of a certain aspect of the present invention includes a first resin portion having a predetermined shape and a second resin portion that is in contact with the first resin portion so as to overlap at least a part thereof. The second resin portion is a two-color molded product comprising the above, and the second resin portion is connected to a laminated region which is in contact with the first resin portion so as to overlap with the first resin portion, and the first resin portion is not laminated on the front side and the back side. It has a layered area and. The monolayer region has a thin portion thinner than the thickness of the adjacent region adjacent to the laminated region. The thin-walled portion is provided on the side opposite to the laminated region with the adjacent region interposed therebetween.

According to this aspect, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region are suppressed.

A step may be provided between the thin portion and the adjacent region. As a result, it is possible to realize a two-color molded product in which air bubbles and thinning in the laminated region are further suppressed.

The single-layer region may be provided with a concave groove inside the thin-walled portion.

The thin portion may have a weld line. As a result, even when a mold for injecting resin from a plurality of gates is used, the molten resin is filled in the thin-walled portion after the laminated region, so that the gas is less likely to be trapped in the laminated region. As a result, it is possible to realize a two-color molded product in which air bubbles and thinning in the laminated region are suppressed.

The first resin portion may be a primary molded product made of a transparent resin.

The first resin portion is a translucent portion of the vehicle lamp cover, and the second resin portion may be made of colored resin. As a result, in the vehicle lamp cover in consideration of design, in which the second resin portion can be seen through the transparent first resin portion, the mixing of air bubbles in the laminated region is suppressed, so that the appearance is poor due to gas burning. Can be reduced.

Another aspect of the present invention is a method for producing a two-color molded product. In this method, a first step of injecting a first resin material into a first cavity formed by a first core mold and a cavity mold to form a first resin portion having a predetermined shape, and a first resin portion. The second core mold and the cavity mold, which are different in shape from the first core mold, are molded so that at least a part of the first resin portion is exposed in a state where the mold is placed inside the cavity mold. Then, the second resin material is injected into the second cavity formed by the second core mold and the cavity mold to form the second resin portion to be joined with at least a part of the first resin portion. And, including. The second core mold and the cavity mold are so that when the second resin material is injected into the second cavity, the second resin material is filled from a portion close to the first resin portion. It is configured to form a flow resistance portion that locally slows the flow of the resin material of 2.

According to this aspect, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region are suppressed.

The second core mold and the cavity mold may be provided with a plurality of gates. The second cavity may have a shape configured such that the region where the first resin portion and the second resin portion are joined is in the middle of the flow path connecting the plurality of gates. As a result, even when the resin is injected into the second cavity from the plurality of gates, the molten resin is filled in the thin-walled portion after the laminated region, so that the gas is less likely to be trapped in the laminated region. As a result, it is possible to realize a two-color molded product in which air bubbles and thinning in the laminated region are suppressed.

It should be noted that any combination of the above components and the conversion of the expression of the present invention between methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to reduce appearance defects in a two-color molded product.

It is an external perspective view of the vehicle which applied the two-color molded article which concerns on this embodiment to the front cover of the headlamp provided in the front part of the vehicle body. It is a schematic front view of the translucent cover which concerns on this embodiment. It is a side sectional view which shows the mold used for the injection molding method. It is a side sectional view which shows the two-color molded article which is injection molded by an injection molding method. 5 (a) and 5 (b) are process diagrams showing an injection molding method according to a reference example. 6 (a) and 6 (b) are process charts showing an injection molding method according to a reference example. 7 (a) and 7 (b) are process charts showing an injection molding method according to a reference example. 8 (a) and 8 (b) are process diagrams showing an injection molding method according to a reference example. FIG. 9A shows a schematic configuration of a cross section in the vicinity of the boundary between the first resin portion which is the primary molded product and the second resin portion which is the secondary molded product in the two-color molded product according to the reference example. A perspective view and FIG. 9B is a cross-sectional view of the vicinity of the boundary between the first resin portion and the second resin portion shown in FIG. 9A. It is a figure which shows typically the flow of the molten resin in the cross section AA of FIG. 9B. 11 (a) is a schematic view showing a schematic configuration of the B region of the translucent cover shown in FIG. 2, and FIG. 11 (b) shows a first resin portion and a second resin portion shown in FIG. 11 (a). It is a CC cross-sectional view near the boundary. It is a front view which shows an example of the secondary core side mold used in the manufacturing method of the two-color molded article which concerns on this embodiment. It is a figure which showed typically the flow of the molten resin in the CC cross section of FIG. 11B. 14 (a) is a cross-sectional view of a main part of the two-color molded product according to the modified example 1, FIG. 14 (b) is a cross-sectional view of the main part of the two-color molded product according to the modified example 2, and FIG. It is sectional drawing of the main part of the two-color molded article which concerns on modification 3. It is a schematic diagram which shows the schematic structure of the main part of the two-color molded article which concerns on modification 4. It is a main part perspective view which shows the schematic structure of the two-color molded article which concerns on modification 5. It is sectional drawing of the main part of the two-color molded article which concerns on modification 6.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings and the like. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

FIG. 1 is an external perspective view of a vehicle in which the two-color molded product according to the present embodiment is applied to the front cover of a headlamp provided on the front portion of the vehicle body. FIG. 2 is a schematic front view of the translucent cover 104 according to the present embodiment. As shown in FIG. 1, left and right headlamps HL are arranged at the front portion of the vehicle body 102 of the vehicle 100. The headlamp HL is mainly composed of a lamp body (not shown) and a translucent cover 104. The lamp body is a container-shaped member having an open front surface, and a translucent cover 104 is attached to the front opening of the lamp body. The configurations of the lamp unit, the reflector, and the like inside the lamp are known, and the description thereof will be omitted.

The translucent cover 104 is a two-color molded product according to the present embodiment, and is manufactured by a method described later. More specifically, the translucent cover 104 includes a translucent resin portion 106 molded of a colorless and transparent translucent resin, and a black resin 108 laminated in the thickness direction at least at least a part of the outer edge of the translucent resin portion 106. , Is integrally molded. In the present embodiment, the translucent resin portion 106 constitutes the first resin portion, and the black resin 108 constitutes the second resin portion.

The translucent resin portion 106 is formed in a plate shape having a substantially uniform thickness that is convexly curved toward the front of the lamp so as to be continuous with the front curved surface of the vehicle body 102 of the vehicle 100, and is emitted from the lamp unit. It is possible to transmit the light to be transmitted and irradiate the front region of the vehicle 100. The translucent resin portion 106 corresponds to the first resin portion in the present embodiment. Similarly, the black resin 108 corresponds to the second resin portion according to the present embodiment.

Next, a manufacturing method of a two-color molded product and a reference example of a mold will be described.

FIG. 3 is a side sectional view showing a mold 50 used in the injection molding method. Further, FIG. 4 is a side sectional view showing a two-color molded product 10 which is injection-molded by an injection molding method.

First, the configuration of the two-color molded product 10 will be described. As shown in FIG. 4, the two-color molded product 10 can be used as a translucent cover 104 for vehicle lamps such as the headlamp shown in FIG. 1, and the front portion 10A and the front portion 10A thereof. It is provided with a peripheral surface portion 10B extending rearward from the outer peripheral edge. At that time, the peripheral surface portion 10B is formed with a flange portion 10Ba extending from the rear end position toward the outer peripheral side and an annular projection portion 10Bb protruding rearward from the rear surface portion.

The two-color molded product 10 has a configuration in which the secondary molded product 14 is arranged around the primary molded product 12. At that time, the primary molded product 12 is composed of a transparent resin member, and the secondary molded product 14 is composed of an opaque (specifically, black) resin member.

The primary molded product 12 and the secondary molded product 14 have a configuration in which the primary molded product 12 is partially overlapped on the peripheral surface portion 10B with the primary molded product 12 positioned on the outer peripheral side. At that time, the rear end surface 12c of the primary molded product 12 is located at the intermediate portion of the peripheral surface portion 10B in the vehicle front-rear direction. A plurality of recesses 12b are formed on the outer peripheral surface (that is, the outer surface of the portion of the peripheral surface portion 10B where the primary molded product 12 is located) 12a of the primary molded product 12 (this will be described later). ..

Next, the configuration of the mold 50 will be described. As shown in FIG. 3, the mold 50 is configured as a so-called opposed type two-color molding mold.

That is, the mold 50 includes a primary core side mold 52 and a secondary core side mold 54 arranged so as to face each other on the X axis extending in the horizontally direction, and these primary core side mold 52 and the primary core side mold 52. A rotating member 56 rotatably arranged around the Y axis extending in the vertical direction orthogonal to the X axis between the secondary core side molds 54, and fixed to the rotating member 56 in a back-to-back state with respect to the Y axis. It includes a pair of cavity-side molds 58A and 58B having the same shape, a movable platen 62 that supports the primary core-side mold 52, and a fixing plate 64 that supports the secondary core-side mold 54.

At that time, the rotating member 56 can move in the X-axis direction with respect to the fixed plate 64, and the movable plate 62 can move in the X-axis direction with respect to the rotating member 56. .. In FIG. 3, the directions of these relative movements are indicated by arrows.

In the mold 50, the heating supported by the movable platen 62 is provided in the primary space portion C1 formed between the primary core side mold 52 and the first cavity side mold 58A which are in contact with each other by mold clamping. A transparent resin material supplied from the cylinder 66 is injected, and the secondary space portion C2 formed between the secondary core side mold 54 and the second cavity side mold 58B, which are in contact with each other by mold clamping. , The black resin material supplied from the heating cylinder 68 supported by the fixing plate 64 is injected.

In the mold 50, hydraulic cylinders 70 are arranged at a plurality of locations of the cavity-side molds 58A and 58B. At that time, the plurality of hydraulic cylinders 70 are arranged at predetermined intervals in the circumferential direction so that the plunger 72 faces the inner peripheral surfaces of the cavity-side molds 58A and 58B. As a result, each of these hydraulic cylinders 70 has a configuration in which the plunger 72 can be projected from the direction orthogonal to the X-axis into the primary space portion C1.

Next, the injection molding method according to the reference example will be described. 5 (a) to 8 (b) are process diagrams showing an injection molding method according to a reference example.

First, as shown in FIG. 5A, the primary core side mold 52 and the secondary core side mold 54 and a pair of cavity side molds 58A and 58B are molded. At that time, the plunger 72 of each hydraulic cylinder 70 arranged in the cavity side mold 58A on the primary core side mold 52 side is projected to the primary space portion C1. On the other hand, the plunger 72 of each hydraulic cylinder 70 arranged in the cavity side mold 58B on the secondary core side mold 54 side is kept in a state of being retracted from the secondary space portion C2. Then, in this state, as shown in FIG. 5B, the transparent resin material supplied from the heating cylinder 66 is injected into the primary space portion C1 to mold the primary molded product 12.

A plurality of plungers 72 are engaged with the primary molded product 12 from a direction orthogonal to the mold opening / closing direction. As shown in FIG. 4, a portion in which the plurality of plungers 72 are engaged is engaged. As a trace of the above, a plurality of recesses 12b are formed on the outer peripheral surface 12a of the primary molded product 12.

Next, as shown in FIG. 6A, the primary core side mold 52 and the secondary core side mold 54 and the pair of cavity side molds 58A and 58B are opened. At this time, the primary molded product 12 tries to be attached to the primary core side mold 52 by the shrinkage action of the resin material injected into the primary space portion C1, but the primary molded product 12 has a mold. Since the plunger 72 is engaged from the direction orthogonal to the opening / closing direction, when the primary core side mold 52 and the cavity side mold 58A are opened, the primary molded product 12 is held by the cavity side mold 58A. It is separated from the primary core side mold 52 as it is. Then, in this state, as shown in FIG. 6B, the rotating member 56 is rotated by 180 ° around the Y axis. At this time, a centrifugal force acts on the primary molded product 12 held by the rotating member 56, but since the plunger 72 is engaged with the primary molded product 12, it is held by the cavity-side mold 58A. The state as it is is maintained.

Next, as shown in FIG. 7A, the primary core side mold 52 and the secondary core side mold 54 and a pair of cavity side molds 58A and 58B are molded. Then, in this state, as shown in FIG. 7B, the black resin material supplied from the heating cylinder 68 is injected into a portion other than the primary molded product 12 in the secondary space portion C2 to inject the secondary molded product. 14 is molded. As a result, the two-color molded product 10 in which the primary molded product 12 and the secondary molded product 14 are integrated is completed.

Next, as shown in FIG. 8A, after the plunger 72 of each hydraulic cylinder 70 arranged in the cavity side mold 58A on the secondary core side mold 54 side is retracted from the secondary space portion C2, The primary core side mold 52 and the secondary core side mold 54 and a pair of cavity side molds 58A and 58B are opened. At this time, since the plunger 72 is not engaged with the primary molded product 12, the two-color molded product 10 is in a state of being attached to the secondary core side mold 54 when the mold is opened. Then, in this state, as shown in FIG. 8B, the two-color molded product 10 is taken out. This extraction is performed by extruding the two-color molded product 10 attached to the secondary core side mold 54 with an extrusion pin (not shown) and grasping it with an extraction machine (not shown).

The inventors of the present application have discovered problems hidden in the production of a two-color molded product by conventional injection molding, including the above-mentioned method, and devised a technique for improving the problems. FIG. 9A shows a schematic configuration of a cross section in the vicinity of the boundary between the first resin portion 22 which is the primary molded product and the second resin portion 24 which is the secondary molded product in the two-color molded product according to the reference example. A perspective view of the main part, FIG. 9B is a cross-sectional view of the vicinity of the boundary between the first resin portion 22 and the second resin portion 24 shown in FIG. 9A.

The two-color molded product 20 includes a first resin portion 22 having a predetermined shape and a second resin portion 24 that is in contact with the first resin portion 22 so as to overlap at least a part thereof. The second resin portion 24 includes a laminated region R1 that is in contact with the first resin portion 22 so as to overlap with the first resin portion 22, and a single layer region R2 that is connected to the laminated region R1 and has no first resin portion 22 laminated on the front side and the back side. Has.

In the two-color molded product 20 having such a structure, if a mold having a structure in which a weld line is formed in the vicinity of the cross section shown in FIGS. 9 (a) and 9 (b) is used, air bubbles are mixed. In some cases, the second resin portion 24 may harden. FIG. 10 is a diagram schematically showing the flow of the molten resin in the AA cross section of FIG. 9B.

The molten resin tends to flow faster when the flowing space is thicker (the wider the space) because the pressure loss is low. Therefore, in a region having a small thickness such as the laminated region R1 shown in FIG. 9B, the flow becomes relatively slow. On the other hand, in a region having a large thickness such as the single layer region R2 shown in FIG. 9B, the flow becomes relatively fast. Therefore, as shown in FIG. 10, when the molten resin 26 flows from a plurality of directions, the single-layer region R2 flows quickly and merges first to form the weld line 28. At that time, since the flow of the laminated region R1 is relatively slow, the weld line 28 is gradually formed toward the first resin portion 22 with the gas (air) G at the time of injection molding remaining in the mold. To. As a result, the gas G cannot be released from the mold and remains as air bubbles or a lack of meat in the second resin portion 24.

Such air bubbles and lack of meat can be identified from the outside when the first resin portion 22 is a transparent resin, which may contribute to poor appearance.

Therefore, the inventors of the present application have come up with a technique for suppressing the occurrence of the above-mentioned appearance defects by devising the shape of the single layer region of the second resin portion.

11 (a) is a schematic view showing a schematic configuration of the B region of the translucent cover 104 shown in FIG. 2, and FIG. 11 (b) shows the first resin portion 30 and the second resin portion shown in FIG. 11 (a). It is a CC sectional view near the boundary with 32.

The translucent cover 104 according to the present embodiment includes a transparent first resin portion 30 having a predetermined shape, and a second resin portion 32 that is in contact with the first resin portion 30 so as to overlap at least a part thereof. The second resin portion 32 includes a laminated region R1 that is in contact with the first resin portion 30 so as to overlap the first resin portion 30, and a single-layer region R2 that is connected to the laminated region R1 and has no first resin portion 30 laminated on the front side and the back side. Has. The single-layer region R2 has a thin-walled region R4 that is thinner than the thickness of the adjacent region R3 adjacent to the laminated region R1. The thin-walled region R4 is provided on the opposite side of the laminated region R1 with the adjacent region R3 interposed therebetween.

In the translucent cover 104 having such a configuration, even if a mold having a configuration in which a weld line is formed in the vicinity of the cross section shown in FIGS. 11 (a) and 11 (b) is used, air bubbles are mixed. It is possible to reduce the phenomenon that the second resin portion 24 is solidified. FIG. 12 is a front view showing an example of the secondary core side mold 54 used in the method for manufacturing a two-color molded product according to the present embodiment.

As shown in FIG. 12, in the method for manufacturing a two-color molded product according to the present embodiment, two or more gates 34 are provided on the secondary core side mold 54. In addition, a plurality of gates may be provided in each of the cavity side mold 58A and the cavity side mold 58B. Alternatively, the secondary core side mold 54 may be provided with one or more gates, and each of the cavity side mold 58A and the cavity side mold 58B may be provided with one or more gates.

FIG. 13 is a diagram schematically showing the flow of the molten resin in the CC cross section of FIG. 11 (b).

As described above, the thicker the flowing space, the faster the molten resin flows. Therefore, in a region having a small thickness such as the thin-walled region R4 shown in FIG. 11B, the flow becomes relatively slow. On the other hand, in the single-layer region R2 shown in FIG. 11B and the adjacent region R3 having a large thickness, the flow becomes relatively fast. In this way, by providing the region where the molten resin flows faster on the side closer to the first resin portion 30, as shown in FIG. 13, when the molten resin 26 flows from a plurality of directions, the adjacent region R3 The flow is fast and first merges to form the weld line 28. At that time, since the flow of the thin-walled region R4 is relatively slow, the gas (air) G at the time of injection molding is discharged in the direction away from the first resin portion 30, and the weld line 28 is gradually discharged from the first resin portion 30. It is formed toward the thin region R4. As a result, the gas G does not stay at the boundary between the first resin portion 30 and the second resin portion 32, and is easily discharged from the mold, so that it is less likely to remain as bubbles or lack of meat in the second resin portion 32. As a result, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region R1 are suppressed.

The thickness t4 of the thin-walled region R4 according to the present embodiment may be smaller than the thickness t3 of the adjacent region R3, but more preferably t4 <0.5 × t3. As a result, the timing at which the thin-walled region R4 is filled with the molten resin can be further delayed, so that it is possible to realize a two-color molded product in which air bubbles and thinning in the laminated region R1 are further suppressed.

In the translucent cover 104 according to the present embodiment, the thickness t1 of the laminated region R1 is about 1 to 4 mm. Further, the thickness t3 of the adjacent region R3 of the single layer region R2 is about 2 to 8 mm. The thickness t4 of the thin region R4 is about 1 to 3 mm.

In at least a part of the translucent cover 104 according to the present embodiment, a step 36 is provided between the thin region R4 and the adjacent region R3. As a result, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region R1 are further suppressed. Further, the single-layer region R2 according to the present embodiment is provided with a concave groove 38 inside the thin-walled region R4. The width W1 of the groove 38 is about 30 ± 20 mm.

In the thin-walled region R4, the thinner the thickness t4 and the wider the width W1 of the portion to be thinned, the more effective it is as a flow resistance portion. There is also. Therefore, it can be adjusted by setting the width W1 of the concave groove 38 to the above range and the thickness t4 of the thin-walled region R4 to the above range. Further, when the width W1 of the concave groove 38 is made extremely narrower than the above range, the thickness t4 of the thin-walled region R4 may be adjusted by making it extremely thinner than the above range. Alternatively, when the width W1 of the concave groove 38 is made extremely wider than the above range, the thickness t4 of the thin-walled region R4 may be adjusted by making it thicker than the above range.

Further, as shown in FIG. 11A, the smaller the height h from the lower surface 30a of the first resin portion 30 to the position where the thin-walled region R4 starts, the more effective the above-mentioned prevention of air bubbles and the like is, but the first resin portion Considering the appearance of the second resin portion 32 that can be seen through from the 30 side, it may be set to about 3 to 10 mm, for example.

Further, the thin-walled region R4 according to the present embodiment has a weld line 28. As a result, even when a mold for injecting resin from a plurality of gates 34 is used, the molten resin is filled in the thin-walled region R4 after the laminated region R1, so that the gas is confined in the laminated region R1. It becomes difficult. As a result, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region R1 are suppressed.

As described above, the first resin portion 30 according to the present embodiment is a translucent portion of the vehicle lamp cover, and the second resin portion 32 is made of colored resin. As a result, in the translucent cover 104 for vehicles in which the design is taken into consideration so that the second resin portion 32 can be seen through the transparent first resin portion 30, air bubbles are suppressed from being mixed in the laminated region R1. , Appearance defects due to gas burning can be reduced.

Next, a method for manufacturing the two-color molded product according to the present embodiment will be described with reference to FIGS. 5 (a) to 8 (b). In this method, a transparent resin material is injected into the primary space portion (first cavity) C1 formed by the primary core side mold 52 and the cavity side mold 58A, and the primary molded product 12 having a predetermined shape is formed. The first step of forming and the primary core side mold 52 are such that at least a part of the primary molded product 12 is exposed in a state where the primary molded product 12 is arranged inside the cavity side mold 58A. The secondary core side mold 54 and the cavity side mold 58A having different shapes are molded, and the inside of the secondary space portion (second cavity) C2 formed by the secondary core side mold 54 and the cavity side mold 58A. Includes a second step of injecting a black resin material into the secondary molded product 14 to form the secondary molded product 14 to be joined to at least a part of the primary molded product 12. When the black resin material is injected into the secondary space C2, the secondary core side mold 54 and the cavity side molds 58A and 58B are filled with the black resin material from the portion close to the primary molded product 12. As described above, it is configured to form a flow resistance portion that locally slows the flow of the black resin material. The flow resistance portion is, for example, a portion forming a thin portion of the secondary molded product 14, in other words, a portion locally protruding in the secondary space portion C2 in a state where the mold is molded. As a result, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region R1 are suppressed.

Further, as described above, the secondary core side mold 54 and the cavity side mold 58A or the cavity side mold 58B are provided with a plurality of gates. Then, in the secondary space portion C2, the region where the primary molded product 12 (first resin portion 30) and the secondary molded product 14 (second resin portion 32) are joined is in the middle of the flow path connecting the plurality of gates 34. It is a shape configured to be (region B'shown in FIG. 12). As a result, even when the resin is injected into the secondary space C2 from a plurality of gates, the molten resin is filled in the thin-walled region R4 after the laminated region R1, so that the gas G is confined in the laminated region R1. It becomes difficult to get rid of. As a result, it is possible to realize a two-color molded product in which mixing of air bubbles and thinning in the laminated region R1 are suppressed.

(Modification example)
14 (a) is a cross-sectional view of a main part of the two-color molded product according to the modified example 1, FIG. 14 (b) is a cross-sectional view of the main part of the two-color molded product according to the modified example 2, and FIG. 14 (c) is. It is sectional drawing of the main part of the two-color molded article which concerns on modification 3.

In the two-color molded product 40 according to the first modification, the thickness t1 of the laminated region R1 is as thick as 3 to 7 mm, and the thickness t4 of the thin-walled region R4 is about 2 to 6 mm.

In the two-color molded product 42 according to the second modification, the thickness t1 of the laminated region R1, the thickness t3 of the adjacent region R3, and the thickness t4 of the thin-walled region R4 are about the same as those of the translucent cover 104 according to the above-described embodiment. is there. However, the change in thickness at the time of transition from the adjacent region R3 to the thin region R4 is not discontinuous (not a step) but continuous (the corners are rounded). As a result, molding defects can be reduced.

The two-color molded product 44 according to the third modification is formed of a flat surface S1 in which the laminated region R1 to the single layer region R2 are continuous inside.

FIG. 15 is a schematic view showing a schematic configuration of a main part of the two-color molded product according to the modified example 4. The main difference between the two-color molded product 46 according to the modified example 4 is that the shape of the concave groove 48 is different from the shape of the concave groove 38 of the translucent cover 104 shown in FIG. 11 (a). .. The concave groove 48 is formed of a curved surface, and has a shape in which the depth gradually becomes shallower as it approaches the first resin portion 30.

Further, the width W1 of the concave groove 48 also has a shape that gradually narrows as it approaches the first resin portion 30. The width W1 of the groove 48 is about 40 ± 20 mm. The height h from the lower surface 30a of the first resin portion 30 to the position where the thin-walled region R4 starts is about 3 mm.

By providing the concave groove 48 having such a shape in the two-color molded product 46, the shape of the end face 48a of the thin-walled region R4 becomes gentle, and the shape of the second resin portion 32 that can be seen through from the first resin portion 30 side can be obtained. Can be made inconspicuous.

FIG. 16 is a perspective view of a main part showing a schematic configuration of the two-color molded product 49 according to the modified example 5. The two-color molded product 49 has substantially the same shape as the translucent cover 104 shown in FIG. 11A, but a part of the second resin portion 32 in the laminated region R1 is exposed to the outside of the two-color molded product 49. The exposed portion 51 is formed. As a result, even if the gas is likely to stay in the laminated region R1, the gas can be guided toward the thin region R4 via the exposed portion 51.

FIG. 17 is a cross-sectional view of a main part of the two-color molded product 80 according to the modified example 6. The two-color molded product 80 according to the modified example 6 includes a second resin portion 32 having a vertical flat surface 32a continuous from the laminated region R1 to the single layer region R2 on the inner side (back side). Further, in the two-color molded product 80, an inclined surface 32b is formed on the outer side (front side) in the adjacent region R3. The thickness t3 of the adjacent region R3 changes so as to continuously decrease from the laminated region R1 side toward the thin-walled region R4 side.

The present invention has been described above based on the embodiments and modifications. It is to those skilled in the art that this embodiment and each modification are examples, and that various modifications are possible for the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. It is about to be understood.

C1 primary space part, R1 laminated area, C2 secondary space part, R2 single layer area, R3 adjacent area, R4 thin wall area, 10 two-color molded product, 12 primary molded product, 14 secondary molded product, 20 two-color Molded product, 22 1st resin part, 24 2nd resin part, 26 molten resin, 28 weld line, 30 1st resin part, 32 2nd resin part, 34 gate, 36 step, 38 concave groove, 40, 42, 44 , 46 Two-color molded product, 48 Concave groove, 48a End face, 49 Two-color molded product, 50 mold, 51 Exposed part, 52 Primary core side mold, 54 Secondary core side mold, 58A, 58B Cavity side metal Mold, 100 vehicle, 102 car body, 104 translucent cover, 106 translucent resin part, 108 black resin.

Claims (6)

A two-color molded product comprising a first resin portion having a predetermined shape and a second resin portion that is in contact with the first resin portion so as to overlap at least a part thereof.
The second resin portion has a laminated region that is in contact with the first resin portion so as to overlap the first resin portion, and a single-layer region that is connected to the laminated region and has the first resin portion not laminated on the front side and the back side. And
The single-layer region has a thin portion thinner than the thickness of the adjacent region adjacent to the laminated region.
A two-color molded product characterized in that the thin-walled portion is provided on the side opposite to the laminated region with the adjacent region interposed therebetween , and is surrounded by a region thicker than the thickness of the thin-walled portion . The two-color molded product according to claim 1, wherein a step is provided between the thin portion and the adjacent region. The two-color molded product according to claim 1 or 2, wherein the thin-walled portion has a weld line. The first resin portion is a translucent portion of a vehicle lamp cover.
The two-color molded product according to any one of claims 1 to 3, wherein the second resin portion is made of a colored resin. The first step of injecting the first resin material into the first cavity formed by the first core mold and the cavity mold to form the first resin portion having a predetermined shape, and
With the second core mold having a shape different from that of the first core mold so that at least a part of the first resin portion is exposed in a state where the first resin portion is arranged inside the cavity mold. The cavity mold is clamped, the second resin material is injected into the second cavity formed by the second core mold and the cavity mold, and the second resin material is joined to at least a part of the first resin portion. 2 Including the second step of forming the resin part
When the second resin material is injected into the second cavity, the second core mold and the cavity mold are filled with the second resin material from a portion close to the first resin portion. As described above, it is configured to form a flow resistance portion that locally slows the flow of the second resin material.
A method for manufacturing a two-color molded product. The second core mold and the cavity mold are provided with a plurality of gates.
The second cavity has a shape such that the region where the first resin portion and the second resin portion are joined is in the middle of the flow path connecting the plurality of gates.
The method for producing a two-color molded product according to claim 5, wherein the two-color molded product is produced.

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