Resin molded products

Abstract

To provide a resin molding with shortened molding time.SOLUTION: A resin molding is molded from a plurality of resins and its runner is assembled with a joint part where a first resin is merged with a second resin; the joint part is assembled with a first joint part molded from the first resin and a second joint part molded from the second resin; the first joint part is formed to a concave shape having a wall part to be in contact with a part of the second joint part.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a resin molded product, a molding apparatus, a molding method, and a mold.

Background Art

[0002] For example, in a multi-color molded product formed using a plurality of resins, there are cases where different resins are connected to each other in the runner portion. Patent Document 1 describes a molding apparatus for molding such a multi-color molded product. In the molding apparatus described in Patent Document 1, a partition member is provided in the runner groove of the mold, and the partition member blocks the flow of the primary molding resin flowing from one side of the runner groove. After the primary molding resin is cured, a secondary molding resin different from the primary molding resin is flowed from the other side of the runner groove. At this time, the partition member is pushed down outside the runner groove by the flow pressure of the secondary molding resin, so that the secondary molding resin flows into the position where the partition member was located and welds to the primary molding resin. Then, a multi-color molded product composed of the primary molding resin and the secondary molding resin having a color different from that of the primary molding resin is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the molding apparatus described in Patent Document 1, if the secondary molding resin reaches the partition member before the primary molding resin is cured, the primary molding resin and the secondary molding resin may be mixed at the position where the partition member was located. Therefore, it is necessary to adjust the injection timing, such as delaying the injection of the secondary molding resin, so that the secondary molding resin reaches the partition member after the primary molding resin is cured, and the molding takes a long time.

[0005] The present invention provides a resin molded product in which the molding time is shortened. [Means for solving the problem]

[0006] According to one aspect of the present invention, for example, a resin molded product is formed from a plurality of resins and has a joint portion in which a first resin and a second resin merge on a runner, wherein the joint portion comprises a first joint portion formed from the first resin and a second joint portion formed from the second resin, and the first joint portion is formed in a concave shape having a wall portion that contacts a part of the second joint portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a resin molded product in which the molding time is shortened. [Brief explanation of the drawing]

[0008] [Figure 1] A cross-sectional view of a molding apparatus according to an embodiment of the present invention. [Figure 2] Perspective view of the main part of the partition member. [Figure 3] (A) is a perspective view of the main part of the runner groove, (B) is a perspective view of the main part of the runner groove showing the partition member in a retracted state, and (C) is an enlarged perspective view of the partition member inside the runner groove. [Figure 4] (A) is a perspective view and (B) is a cross-sectional view of a runner in a resin molded product according to the first embodiment of the present invention. [Figure 5] Figure 4 shows a perspective view of the runner of a resin molded product (A) and a cross-sectional view (B). [Figure 6] (A) is a cross-sectional view of the mold after the injection of the first resin is complete, and (B) is a cross-sectional view of the mold after the injection of the second resin is complete. [Figure 7] A cross-sectional view of the main part of the runner groove according to the second embodiment of the present invention. [Figure 8] (A) is a cross-sectional view of the mold after the injection of the first resin is complete, and (B) is a cross-sectional view of the mold after the injection of the second resin is complete. [Figure 9](A) is a perspective view and (B) is a cross-sectional view of a runner in a resin molded product according to a second embodiment of the present invention. [Figure 10] Figure 9 shows a runner of a resin molded product; (A) is a perspective view, and (B) is a cross-sectional view. [Modes for carrying out the invention]

[0009] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals indicate the same elements. In each figure, the up, down, left, and right directions relative to the paper will be used as the up, down, left, and right directions of the device in this embodiment in the description below. In the embodiments described below, the present invention is not limited to resin materials of different colors used as molding materials, and can be applied to molding materials such as different materials (thermoplastic resins such as polystyrene, polyethylene, and ABS, thermosetting resins, metals, etc.) and resins of different transparency.

[0010] <First Embodiment> 1 is a molding apparatus, which includes a known injection molding device (not shown), and consists of a movable mold body 2 attached to the movable side of the injection molding device and a fixed mold body 3 attached to the fixed side of the injection molding device. Figure 1 is a cross-sectional view of the entire molding apparatus 1 with the movable mold body 2 joined to the fixed mold body 3.

[0011] The movable mold body 2 consists of a male mold mounting plate 6 to which the male mold (movable mold) 5 is attached, a fixed base 7 for fixing the male mold mounting plate 6, a movable side mounting plate 9 attached to the injection device, and spacers 10 provided on both sides between the fixed base 7 and the movable side mounting plate 9. 11 and 12 are recesses that connect injection nozzles for injecting different colored molding resin materials into a mold 18 formed between the male mold 5 and the female mold 51 (described later) via runner grooves 15 and 16.

[0012] A void 19 is formed in the fixed base 7, and an extrusion plate 20 is movably installed within this void 19. Multiple knockout pins 21 are embedded in the extrusion plate 20. Each knockout pin 21 penetrates the male mold mounting plate 6, male mold 5, etc., and its tip retracts into the mold 18 and runner grooves 15, 16, and is configured to extrude the multi-color molded product 24 formed in the mold 18 and the multi-color runner R formed in the runner grooves 15, 16, as described later. The extrusion plate 20 is fixed to a pressing shaft 25 inserted through holes 22, 23 formed approximately in the center of the fixed base 7 and approximately in the center of the movable side mounting plate 9.

[0013] The fixed base 7 has a mounting hole 29 that is open on the side of the fixed mold body 3, and the rear part of the partition member 30 is slidably mounted within this mounting hole 29. Coil springs 31a and 31b are provided within this mounting hole 29 to bias the rear ends of the partition members 30a and 30b toward the fixed mold body 3. Alternatively, a flange 32 may be formed on the rear of the partition member 30a, and this flange 32 may be engaged with a stepped portion 33 formed in the mounting hole 29 to restrict the range of movement of the partition member 30a. The partition members 30a and 30b are pressed against the female mold (fixed side mold) 51, described later, with their tips dividing the runner groove 16 and the inside of the molding die 18 into at least two sections.

[0014] The fixed mold body 3 consists of a fixed-side mounting plate 50 attached to an injection device (not shown), a female mold mounting plate 52 to which the female mold 51 is attached, and spacers 53 provided on both sides between these plates. 55 is an injection nozzle connecting recess formed in the fixed-side mounting plate 50. The tip of the injection nozzle attached to this connecting recess 55 is connected to a sprue hole 56 formed in the female mold mounting plate 52 and the female mold 51. This sprue hole 56 is formed to communicate with runner grooves 15 and 16.

[0015] <Partition member 30a> Referring to FIGS. 1 and 2, the partition member 30a will be described in detail. The partition member 30a is provided in the runner groove 16 of the moving die body 2 (or the fixed die body 3) so as to be able to enter and exit the runner groove 16 to partition the inside of the runner groove 16. This partition member 30a is biased in the direction of exiting the runner groove 16 by an elastic member 31a.

[0016] As shown in FIG. 2, the partition member 30a that partitions the runner groove 16 is not particularly limited in cross-sectional shape, but in this embodiment, it is formed in a round shaft shape. When it is in a round shaft shape, it is easy to process the die that houses the partition member 30a, and the partition member 30a can be manufactured by processing a protruding pin that has been conventionally used. Note that the partition member 30a is not limited to a round shaft shape and may be formed in a prismatic shape.

[0017] A small-diameter portion 35 is formed at the tip of the partition member 30a. The tip of this small-diameter portion 35 is biased by a coil spring 31a, protrudes into the runner groove 16, and is pressed against the female die 51. One surface (the inner surface in FIG. 2, the regulating surface) 36 of this small-diameter portion 35 is substantially perpendicular to the flowing direction of the molding resin material flowing in the runner groove 16 described later. Also, a stepped recess 40 that opens up to the upper end surface 39 of the partition member 30a is formed on the other surface (the front surface in FIG. 2) 37.

[0018] The shape of the stepped recess 40 is not particularly limited. For example, the stepped recess 40 shown in FIG. 2 includes a recess 40a that forms a hemispherical depression formed at the center of the upper end surface with a circular cross-section, and a notch portion 40b that is cut out from this hemispherical depression toward the other surface (the front surface in FIG. 2) 37 side.

[0019] Figure 3(A) shows a perspective view of the male mold 5 with the partition member 30a housed in the runner groove 16. A pair of aperture pins 16a are also arranged in the runner groove 16 so as to sandwich the partition member 30a. The aperture pins 16a suppress the momentum of the flowing resin and prevent the resin from flowing over the partition member 30a to the other side. Adjacent to the partition member 30a, the runner groove 16 has a projection 16b that protrudes into the runner groove 16 on one side (regulating surface) 36 of the partition member 30a, and forms a concave portion 17a on the runner R, which will be described later, having a wall portion 17a1 that covers a part of the partition member 30a. Figure 3(B) shows the partition member 30a housed in the runner groove 16 of the male mold 5 in the retracted position. Figure 3(C) shows an enlarged perspective view of the partition member 30a. Note that Figures 3(A), 3(B), and 3(C) show the state in which the runner groove 16 is not filled with resin.

[0020] <Runner R> The runner R in this embodiment will be described with reference to Figures 4 and 5. Figures 4(A) and 5(A) are perspective views of the runner R that constitutes a part of a resin molded product according to the first embodiment of the present invention. Figure 4(B) is a cross-sectional view taken along line IV-IV in Figure 4(A). Figure 5(B) is a cross-sectional view taken along line VV in Figure 5(A). As shown in Figure 4(A), the runner R comprises a first runner portion A1 formed of a first resin A, a second runner portion B1 formed of a second resin B, and a joint portion 17 where the first resin A and the second resin B meet. Therefore, the runner R forms a part of a resin molded product molded from multiple resins. The first runner portion A1 and the second runner portion B1 are arranged on opposite sides of each other via the joint portion 17 and each comprises openings A2 and B2 formed by a throttling pin 16a.

[0021] The joint portion 17 comprises a first joint portion 17a molded from the first resin A and a second joint portion 17b molded from the second resin B. The second joint portion 17b is molded within the runner groove 16 by the retraction of the partition member 30a, which will be described later, and therefore comprises a bottom portion that transfers the shape of the stepped recess 40 of the partition member 30a and a cylindrical portion with the same diameter as the small diameter portion 35 of the partition member 30a.

[0022] On the other hand, the first joint portion 17a is formed in a concave shape having a wall portion 17a1 that contacts a part of the side surface of the cylindrical portion of the second joint portion 17b and a bottom portion (deep portion) 17a2. In other words, the concave shape consists of a bottom portion 17a2 and a wall portion 17a1 erected around the bottom portion 17a2. However, the concave shape is not limited to the above, and for example, instead of the space defined by the bottom portion 17a2 and the side wall 17a1, a hemispherical recess may be adopted, such as the recess 40a of the stepped recess 40. In other words, it may be a concave shape without a bottom. By doing so, the shape of the projection portion 16b, which will be described later, can be made simpler.

[0023] In this embodiment, the bottom portion 17a2 is shaped by cutting an arc, which is the cross-sectional shape of the second joint portion 17b, from one side of a rectangle. A portion of the wall portion 17a1 erected on the arc-shaped part of the bottom portion 17a2 is positioned to cover the side surface of the second joint portion 17b. The inner circumferential surface of the wall portion 17a1 is formed along a portion of the second joint portion 17b. In this way, the side surface of the second joint portion 17b can be covered with a portion of the thin wall portion 17a1, and the bonding force between the first joint portion 17a1 and the second joint portion 17a2 can be effectively strengthened with a small volume of resin (see Figure 4(B)).

[0024] On the other hand, for example, if the second joint portion 17b is a rectangular prism with a rectangular cross-section, the wall portion 17a1 of the first joint portion 17a can be a partially straight wall portion 17a1 that contacts one side of the rectangular prism of the second joint portion 17b. In other words, the wall portion 17a1 is not limited to, for example, a curved shape, but may also be composed of straight lines.

[0025] The details of the first joint portion 17a will be explained with reference to the cross-sectional view shown in Figure 5(B). If the diameter of the second runner portion B1 (the same applies to the first runner portion A1), which has a circular cross-section, is R1, then the thickness of the first joint portion 17a is t1. In this case, the thickness t1 is set to be smaller than the diameter R1. For example, if R1 is set to approximately 3.0 mm, the thickness t1 may be set to approximately 1.5 mm. In other words, the first joint portion 17a is formed to be thinner than either the first runner portion A1 or the second runner portion B1.

[0026] Furthermore, in Figure 5(B), at least a portion of the inner circumferential surface 17a1a of the wall portion 17a1a is an inclined surface that slopes outward from the concave shape at an angle Θ1 as it moves from the concave bottom portion 17a2 towards the top of the wall portion 17a1. Also, at least a portion of the outer circumferential surface 17a1b of the wall portion 17a1 is an inclined surface that slopes inward from the concave shape at an angle Θ2 as it moves towards the top of the wall portion 17a1. For reference, the inclination angles Θ1 and Θ2 can be exemplified as approximately 5 degrees.

[0027] The wall portion 17a1 is configured such that its horizontal cross-sectional area gradually decreases from the bottom portion 17a2 towards the top of the wall portion 17a1. In other words, by making the inner and outer surfaces of the wall portion 17a1 inclined surfaces, the force acting on the first joint portion 17a when removing the runner R from the mold can be reduced, and unnecessary force can be prevented from acting on the fastening point between the first joint portion 17a and the second joint portion 17b. Therefore, when removing the runner R from the mold, it is possible to prevent the connection between the first joint portion 17a and the second joint portion 17b from being released and separating. In addition, by suppressing the application of unnecessary force to the fastening point between the first joint portion 17a and the second joint portion 17b when removing from the mold, it is possible to prevent the connection between the first joint portion 17a and the second joint portion 17b from already being weakened at the time of molding completion. Therefore, even when the resin molded product according to this embodiment is applied to the plastic model parts and supporting runners in a plastic model kit, it is possible to suppress situations in which the connection between the first joint part 17a and the second joint part 17b becomes detached due to vibration or shock while the plastic model kit is being transported in its product packaging box.

[0028] Furthermore, in this embodiment, since the wall portion 17a1 and the bottom portion 17a2 constituting the first joint portion 17a are each formed of thin-walled material, the force acting on the first joint portion 17a when removing the runner R from the mold can be further reduced, and the hardening of the first joint portion 17a, as described later, can be accelerated. For example, if the thickness t1 of the first joint portion 17a is about 1.5 mm, the thickness of the bottom portion 17a2 can be about 0.5 mm.

[0029] Furthermore, the first joint portion 17a is molded with a smaller volume than the volume of the adjacent first runner portion A1 at the same length as the first joint portion 17a. Specifically, referring to Figure 5(A), let d1 be the axial length of the first joint portion 17a, and d2 be the same axial length as the first joint portion 17a in the first runner portion A1. d1 and d2 are the same length. In this case, the volume of the first joint portion 17a at length d1 is set to be smaller than the volume of the first runner portion A1 at length d2. Conventionally, the portion corresponding to the first joint portion was molded as a solid, for example, material with a thickness of approximately 2.5 mm.

[0030] In other words, as described above, the first joint portion 17a is set to be thinner than the first runner portion A1, and furthermore, it has a concave shape composed of a thin wall portion 17a1 and a bottom portion 17a2, so it has a smaller volume compared to the first runner portion A1 of the same length. By doing so, the volume of the first joint portion 17a is reduced compared to the first runner portion A1 adjacent to the first joint portion 17a, and the contact area with the mold is increased, which allows the hardening of the first joint portion 17a to occur faster during molding, as described later.

[0031] <Forming process> The molding process of the runner R in the first embodiment will be described with reference to Figures 6(A) and 6(B). The cross-sectional views shown in Figures 6(A) and 6(B) are, for example, cross-sectional views obtained by cutting the mold along the line VI-VI in Figure 3(A). First, as shown in Figure 1, when the male mold 5 and female mold 51 are closed, an injection device (not shown) is connected to the mold and injects the first resin A flowing from one side of the runner groove into the molding space 18 and the runner groove 16 from, for example, a recess 11 connecting the injection nozzle (first injection process). Then, without waiting for the injection of the first resin A to be completed, the injection device injects the second resin B flowing from the other side of the runner groove 16 into the mold from, for example, a recess 12 connecting the injection nozzle (second injection process).

[0032] In the first injection process, the first resin A flows from the left side to the right side of the figure, as shown in Figure 6(A), and fills the space within the runner groove 16 where the projection 16b is located on one side (regulating surface) 36 of the partition member 30a. At this time, the regulating surface side of the partition member 30a restricts the flow of the first resin A flowing from one side (left side in the figure) of the runner groove 16 (regulating process). In other words, one side 36 of the partition member 30a is approximately perpendicular to the inflow direction of the molded resin material, and the flow of the molded resin material flowing to this side 36 can be blocked. The first resin A is then blocked by one side 36 of the partition member 30a, and its flow stops.

[0033] At this time, the first resin A forms a concave first joint portion (concave portion) 17a within the runner groove 16 on one side (regulating surface) 36, which has a wall portion 17a1 and a bottom portion 17a2 surrounding a part of the partition member 30a (first molding step). Referring to Figures 3(A) and 3(C), the projection 16b in the runner groove 16 has a first side surface 16b1 facing the surface 16d of the runner groove 16 and a second side surface 16b2 that is spaced a predetermined distance from one surface of the partition member 30a and runs along a part of the partition member 30a. As shown in Figure 3(C), the second side surface 16b2 is spaced a predetermined distance d from one surface of the partition member 30a. As described above, the wall portion 17a1 of the first joint portion 17a has an inclined surface, so at least the first side surface 16b1 of the projection 16b and the surface 16d of the runner groove 16 are formed as inclined surfaces.

[0034] As described above, the concave first joint portion 17a is formed by a thin wall portion 17a1 and a bottom portion 17a2, and its volume is set to be small, so it hardens quickly. In other words, the first joint portion 17a has a thin bottom portion 17a2 and a thin wall portion 17a1 surrounding it, due to the projection 16b of the runner groove 16, so the contact area with the mold is widened and it hardens quickly.

[0035] For example, in a runner groove 16 where the projection 16b is not formed, a solid runner without a concave shape is formed in the area corresponding to the first joint portion. In this case, a predetermined time is required for the inside of the solid runner to cool, so it takes a predetermined time to harden compared to the concave first joint portion 17a as in this embodiment. Therefore, the concave first joint portion 17a molded from the first resin A hardens more quickly than in the conventional method (hardening process).

[0036] Next, as shown in Figure 6(B), a second resin B of a different color, for example, is injected into the runner groove 16 by an injection nozzle connected to the connecting recess 55. When the second resin B flows in from the other side of the runner groove 16 (from right to left in the figure), it is temporarily blocked by the other surface 37 of the small diameter portion 35 of the partition member 30a, but then flows into the stepped recess 40. Due to the flow pressure of this second resin B, the hemispherical recess 41a of the stepped recess 40 is pressed in the direction of arrow A, and the partition member 30a is pushed down against the biasing force of the elastic member 31a. This state is shown in Figure 3(B). Therefore, the partition member 30a is retracted from the runner groove 16 by the flow of the second resin B flowing from the other side of the runner groove 16 (retraction step). In this way, the second resin B forms a joint that joins with the concave shape formed in the first molding step (second forming step).

[0037] In other words, by the time the second resin B reaches the partition member 30a, the curing of the first joint portion 17a is complete. Therefore, after the first injection unit injects the first resin A, the second injection unit can inject the second resin B without waiting for the injection of the first resin A to be completed. Consequently, it is possible to provide a resin molded product with a shortened molding time.

[0038] The timing at which the second resin B reaches the partition member 30a is appropriately changed depending on the position from the mold gate to the partition member 30a and projection 16b of the present invention. However, the hardening of at least the portion corresponding to the first joint portion 17a is accelerated compared to conventional methods, shortening the injection molding cycle and improving the freedom of mold design. In terms of the molding cycle, for example, when comparing the application of the present invention to a conventional method using the same mold design, the cycle is shortened by 3 seconds.

[0039] As shown in Figure 4, the molded runner R has a cylindrical second joint portion 17b, which corresponds to the shape of the partition member 30a, fitted into a curved surface formed by a part of the wall portion 17a1 of the first joint portion 17a. In other words, the first joint portion 17a forms a molded recess that encloses half of the small diameter portion of the second joint portion 17b, and the second joint portion 17b is encased in this molded recess, resulting in a strong weld between the first joint portion 17a made of the first resin A and the second joint portion 17b made of the second resin B. Therefore, even when the resin molded product according to this embodiment is applied to the parts of a plastic model kit and the runner that supports them, it is possible to suppress situations in which the weld between the first joint portion 17a and the second joint portion 17b is released due to vibration or impact while the plastic model kit is being transported in a product packaging box.

[0040] Subsequently, by separating the movable mold body 2 shown in Figure 1 from the fixed mold body 3 and pressing the pressing shaft 25 to move the extrusion plate 20, the knockout pins 21 provided on the extrusion plate 20 push out the multi-color runner R and multi-color molded product attached to the male mold 5 of the movable mold body 2, allowing them to be removed. In the above embodiment, the partition member 30 and the projection 16b are provided on the movable mold body 2 side, but they may also be provided on the fixed mold body 3 side. In addition, a coil spring 31 is used as the elastic member that biases the partition member 30, but other elastic parts such as rubber or leaf springs may also be used.

[0041] <Second Embodiment> Figures 7 and 8 illustrate a configuration in which a pair of partition members 100 are arranged within the runner groove 85 so as to sandwich the projection 127, and the restricting surface 106 of each partition member 100 is positioned opposite the projection 127. The difference from the first embodiment is that a pair of partition members 100 are provided; the other configurations are the same as those of the first and second embodiments.

[0042] The partition member 100 is formed in a round shaft shape, similar to the partition member 30a shown in Figure 2, with a stepped recess 110 at its tip and a flange 102 at its lower end. The rear of the partition member 100 is slidably mounted in an axial hole 99 formed in the front extrusion plate 90. The flange 102 of the partition member 100 is slidably attached to a sliding hole 96 in the front extrusion plate 90 and is biased in the direction of the runner groove 85 by a spring 101 provided in a spring receiving hole 104 of the rear extrusion plate 91, and engages with the upper wall 103 of the sliding hole 96.

[0043] Furthermore, the flange 102 is designed to be pushed down against the elasticity of the spring 101 until it contacts the stepped portion 117 formed at the top of the spring receiving hole 104. In addition, an engagement groove 116 is formed on one side of the sliding hole 96, and an engagement shaft 115 provided on the flange 102 is designed to slidably engage with this engagement groove 116. As a result, the partition member 100 does not rotate.

[0044] The tip of the partition member 100 is biased by the elasticity of the coil spring 101, protruding into the runner groove 85 and pressing against the female mold 122. One surface 106 of the partition member 100 is approximately perpendicular to the direction of flow of the molded resin material flowing within the runner groove 85. The other surface 107 has a stepped recess 110 that opens up to the upper end surface 109 of the partition member 100. These partition members 100 come in pairs and protrude into each runner groove 85. The two partition members 100, 100 are arranged so that one surface 106, 106 faces the other.

[0045] As shown in Figure 8(A), the injection device injects the first resin A from one side (left side in the figure) of the runner groove 85. This first resin A flows into a stepped recess 110 formed on the other side 107 of the partition member 100 on the left side in the figure. The flow pressure of this first resin A presses against the bottom surface 111 of the stepped recess 110, and the partition member 100 on the left side in the figure is pushed down against the biasing force of the elastic member 101. The first resin A continues to flow through the runner groove 85 and is blocked by one side 106 of the next partition member 100, stopping the flow. At this time, a concave first joint portion 217a is formed.

[0046] As shown in Figure 8(B), when the injection molding device introduces a second resin B of a different color from the other side (right side in the figure) of the runner groove 85, this second resin B flows into a stepped recess 110 formed on the other surface 107 of the partition member 100 on the right side in the figure. The flow pressure of this second resin B presses down the bottom surface 111 of the stepped recess 110, pushing down the partition member 100 on the right side in the figure against the biasing force of the elastic member 101. The second resin B of the different color flows into the position where the partition member 100 on the right side in the figure was located and welds to the first resin A. In this way, a multi-colored runner 84 is formed within the runner groove 85.

[0047] The runner 84 formed as described above is shown in Figures 10 and 11. The runner 84 shown in Figures 10 and 11 is the same member as the runner R shown in Figures 5 and 6, indicated by the prefix "2" in its reference numeral. The runner 84 has the same shape as the runner R except that the first joint portion 217a has a portion 200 that corresponds to the partition member 100.

[0048] In the second embodiment described above, for example, partition members 100 are arranged on both sides of the projection 127 of the runner groove 85, so that the injection can be performed simultaneously without adjusting the injection timing of each injection nozzle. In this way, by providing a pair of opposing partition members 30 within a single runner groove, if either the first resin A or the second resin B reaches the projection 127 first, the hardening of that resin will be accelerated, so that the injection can be performed simultaneously without adjusting the injection timing of each injection nozzle, and the molding efficiency can be further improved.

[0049] As described above, in this embodiment, there is no need to wait for the joint portion to harden as in conventional molding equipment, and the injection time when molding multi-color runners or multi-color molded products can be shortened with an extremely simple mechanism that only requires the provision of protrusions in a single mold. Furthermore, because the mechanism is simple, can be made small and lightweight, it can be manufactured at low cost, and even when attached to an injection molding machine, it places less burden on the injection molding machine. Moreover, since it is not necessary to inject each color of molding resin material sequentially, and it is possible to injection mold them simultaneously, the molding cycle of the molded product is greatly shortened, production efficiency is increased, and production costs can be reduced.

[0050] Furthermore, because the amount of the first resin A in the joint portion near one side of the partition member is reduced, the first resin A near one side of the partition member hardens faster compared to conventional molding devices. As a result, the second resin B can be injected faster than in the case of conventional molding devices, improving molding efficiency and increasing the freedom of mold design. The present invention is applicable to resin molded products that are distributed in a state where the molded product and the runner are not separated, such as plastic model kits. [Explanation of Symbols]

[0051] 17a First joint section, 17a1 Wall section, 17b Second joint section, A First resin, B Second resin, 84, R Runner

Claims

1. A resin molded product formed from multiple resins, having a joint portion where a first resin and a second resin merge on a runner, The joint portion comprises a first joint portion that connects to the first resin runner and a second joint portion that connects to the second resin runner. The first joint portion is formed to include a concave shape having a wall portion that contacts a part of the second joint portion, The aforementioned concave shape is defined by a bottom portion and a side wall including the wall portion erected around the bottom portion, and is characterized by being concave in a direction intersecting the direction of the runner connected to the joint portion.

2. The resin molded product according to claim 1, characterized in that the wall portion covers the part of the second joint portion.

3. The resin molded product according to claim 1 or 2, characterized in that at least a portion of the inner circumferential surface of the wall portion is an inclined surface that slopes outward from the concave shape as it moves from the bottom of the concave shape toward the top of the wall portion.

4. The resin molded product according to any one of claims 1 to 3, characterized in that the inner circumferential surface of the wall portion is formed along a part of the second joint portion.

5. The resin molded article according to any one of claims 1 to 4, characterized in that at least a portion of the outer surface of the wall portion is an inclined surface that slopes inward toward the concave shape as it approaches the top of the wall portion.

6. The resin molded article according to any one of claims 1 to 5, characterized in that the first joint portion is molded in a volume smaller than the volume of the same length as the first joint portion of the adjacent runner.

7. The resin molded product according to any one of claims 1 to 6, wherein the bottom portion defining the concave shape and the side wall are thinner than the runner, and the first joint portion is formed to be thinner than the runner.

Images