JP3270771B2 - Two-color molding method and injection molding apparatus for plastic products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-color forming method for plastic products and an injection molding apparatus.

[0002]

BACKGROUND OF THE INVENTION Some plastic containers, which are widely used as containers for storing or transporting goods, such as food, are color-coded in the left-right direction, so that the direction of the container can be visually recognized. Some are identified.

By the way, when such a two-color container is integrally formed by injection molding, in order to supply the two-color resin into the cavity of the mold, two injection molding machines for injecting resins of different colors from each other are required. Equipment is required.

Generally, when such two-color molding is performed, if the cylinders of these injection devices are arranged in parallel,
Conventionally, since the injection device is large, conventionally, sprues are protruded on the left and right side surfaces of the mold to introduce the two-color resin injected from the nozzle of the injection device arranged in this way into the cavity, The sprue end was in contact with the nozzle end of the injection device.

[0005] When the sprues are provided on the left and right sides of the mold in this manner, when the two injection devices for two-color molding are switched to those for single-color molding, the mold is once disassembled. However, it is necessary to replace the sprue and the like for a single color and to install the mold again, and there is a problem that workability is poor.

In view of the above, Japanese Patent Application Laid-Open No. Sho 60-195
As shown in the conventional example of FIG. 4 described in Japanese Patent Publication No. 15, the cylinders of the two injection devices are arranged obliquely with respect to the mold moving direction so as to intersect on an extension line, and near the intersection. In addition, there is a type provided with a single runner block 18 in which resin passages for guiding two colors of resin into a mold are collectively formed. According to the molding method using such an injection device, the installation space near the mold can be reduced,
In addition, the length of the runner can be reduced.

[0007] However, such a method has the following problems. That is, the injection devices 15a, 1
Although the cylinders 5b are arranged so as to intersect on the extension line, the end faces of the runner blocks 18 arranged in the fixed base 17 are formed at right angles to the moving direction of the mold. The nozzles 13a, 13b and the resin passages 12a, 12b formed in the runner block 18 have poor contact with each other, whereby the flow of the resin is disturbed, and in some cases, the resin leaks. .

Further, two injection devices 15 for two-color molding are used.
When a and 15b are used by switching to those for single-color molding, the mold is once disassembled, the runner block or the like provided in the recess of the mold is replaced with a single-color mold, and the mold is again replaced. It had to be installed, the workability was poor, and further improvement was desired.

[0009]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a two-color molding method for a plastic product, in which the flow of the two-color resin is good and which can be easily switched from the two-color molding to the single-color molding. An object is to provide a molding device used for the same.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, a two-color molding method for a plastic product according to the present invention is provided with two heating cylinders for individually melting thermoplastic resins colored differently from each other. A plastic product in which resins of different colors injected from a heating cylinder are guided to a mold runner, the resins are supplied to the cavity from the runner, and the resins are merged and integrally molded in the cavity. In the two-color molding method, the heating cylinder is disposed so as to be substantially parallel, and the heating cylinder is provided with a detachable manifold member, and the manifold member is provided with the heating cylinder. A resin receiving port is provided at a position corresponding to the injection port, and a resin injection port is provided at a position corresponding to the resin receiving port provided on the runner of the mold. And an injection molding device provided with a resin passage communicating the resin receiving port and the resin injection port.

[0011] In a preferred embodiment of the present invention,
The manifold member is provided with two resin passages that communicate the resin receiving port and the resin injection port,
In addition, these two resin passages are formed closer to each other on the runner side of the mold than on the cylinder side.

[0012] The injection molding apparatus according to the present invention is equipped with two heating cylinders for melting the thermoplastic resin separately,
The resin injected from these heating cylinders is guided to a mold runner, the resin is supplied to the cavity from the runner, and the resins are joined together in the cavity to form a plastic product. In the apparatus, the heating cylinder is disposed so as to be substantially parallel, and the heating cylinder is provided with a detachable manifold member, the manifold member corresponding to an injection port of the heating cylinder. A resin receiving port is provided at a position corresponding to the resin receiving port provided at a position corresponding to the resin receiving port provided at the runner of the mold, and a resin passage communicating the resin receiving port and the resin injection port is provided. It is characterized by being.

[0013] In a preferred embodiment of the present invention,
The manifold member is provided with two resin passages that communicate the resin receiving port and the resin injection port,
In addition, these two resin passages are formed closer to each other on the runner side of the mold than on the cylinder side.

According to the above-described method, since it is not necessary to project sprues on the left and right sides of the mold, the width of the mold can be reduced and the mold processing can be simplified. Further, the workability is excellent, for example, there is no need to arrange two heating cylinders obliquely toward the resin receiving port provided at the center of the mold runner. Further, since the nozzle portion provided at the die side end of the manifold and the runner of the die are in close contact with the cylinder arranged substantially in parallel, there is no resin leakage. In the case of performing single-color molding, the manifold member for two-color molding can be detached from the heating cylinder and easily replaced with a single-color manifold member. This replacement operation can be performed on the heating cylinder side without disassembling the mold, and is excellent in workability.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a two-color molding method and an injection molding apparatus for a plastic product according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a perspective view of a two-color container 1 of a stacking / nesting type. FIG. 2 is a longitudinal sectional view of an injection molding apparatus provided with a two-color molding manifold used in the present embodiment. FIGS. 3A and 3B are longitudinal sectional views of an injection molding apparatus provided with a monochromatic molding manifold used in another embodiment of the present embodiment.

First, the shape of the two-color container formed in this embodiment will be described. In FIG. 1, the two-color container 1 includes a bottom plate 3, a pair of side walls 2 c and 2 d erected from the peripheral edge of the bottom plate 3, and a pair of end side walls 2 a and 2 b. The two-color container 1 includes a bottom plate 3 and side walls 2.
Two colors are indicated by the merging line L on c and 2d.

In the present embodiment, the two-color container 1 as described above is converted into two types by using an injection molding apparatus provided with an injection molding die 100 having a cavity 10 corresponding to the container shape as shown in FIG. , For example, a two-color thermoplastic resin is injected and integrally molded.

The injection mold 100 shown in FIG. 2 is similar to the mold shown in FIG.
In 0, a movable mold (male mold) 8 and a fixed mold (female mold) 9
Thus, a cavity 10 having a shape corresponding to the container 1 as described above is formed. A runner block 11 having an auxiliary block 18 is fixed to one side of the fixed mold 9.

The auxiliary block 18 is provided at the deepest part of the central recess 70 on the heating cylinder 14a, 14b side of the mold 100 so as to protrude in the direction of the heating cylinder 15a, 15b (toward the resin injection nozzle of the manifold member). Have been.
The resin suction port side end surface 72 of the auxiliary block 18 is
The resin passage 12a is formed so as to be orthogonal to the movement direction of the resin passage 12a so that resin injected from a manifold member 60 described later can be sucked into a spherical recess provided on the suction-port-side end face 72. , 12b are open.

The runner block 11 is disposed between the auxiliary block 18 and the fixed mold 9, and the runner block 11 has a resin passage 12 in the auxiliary block 18.
a, 12b, two runners 11a, 1
1b extend in opposite directions so as to be substantially parallel to the bottom surface 3 of the cavity 10. Runner 1
The gates 1a and 11b communicate with the cavity 10 by gates (passages) 16a, 16a, 16b and 16b provided at two locations.

In FIG. 2, two injection devices 15a and 15b for supplying the resin to the mold 100 are provided with a movable mold 8
Are arranged substantially in parallel with the moving direction of. The two injection devices 15a and 15b have heating cylinders 14 respectively.
a, 14b, the heating cylinders 14a,
At each resin injection port 50a, 50b of the 14b, a manifold member 60 as described below is detachably provided, and the manifold member 60 is provided at the time of injection molding.
It comes into close contact with the auxiliary block 18 of the mold 100.

That is, the manifold member 60 includes:
Resin receiving ports 80a and 80b are provided at positions corresponding to the injection ports 50a and 50b of the heating cylinders 14a and 14b, respectively.
a, 50b and resin receptacles 80a, 8 of manifold 60
0b is tightly fixed by a bolt or the like (not shown). In addition, the nozzle member 62 protrudes from the manifold member 60 at a position corresponding to the resin receiving ports 73a and 73b provided in the auxiliary block 18 of the mold 100, and an opening 73a of the auxiliary block 18 , 73b are provided with resin injection ports 13a, 13b projecting therefrom. Moreover, the manifold member 60 has the resin receiving ports 80a, 80b and the resin injection ports 13a, 13a.
b are provided with resin passages 82a and 82b communicating with each other. Also, in FIG. 2, these two resin passages 82a, 82
2b is formed closer to the runner side of the mold than to the cylinder side. In other words, the cylinder-side resin inlet 80
The distance between the resin injection ports 13a and 13b on the auxiliary block 18 side is smaller than the distance between a and 80b.

Therefore, such a manifold member 60
Is used, a resin suction port (supply port) 73 is provided at the center of the mold.
Even if a and 73b are formed close to each other, the two-color molding of the molded body can be performed while the two heating cylinders 14a and 14b are arranged in parallel to the moving direction of the mold. In other words, there is no need to direct the two heating cylinders 14a and 14b toward the auxiliary block 18 provided at the center of the mold, and the workability is excellent. In addition, by using the mold 100 in which the resin suction ports (supply ports) 73a and 73b are provided at the center of such a mold, the mold width can be reduced even in the case of two-color molding. The fabrication of the mold is also easy.

In the above description, an example in which the two-color container 1 is integrally molded using the injection mold shown in FIG. 2 has been described. However, the injection mold used in the present invention is not limited to this example. Not something.

For example, the number of gates communicating with the cavity 10 may be such that at least one gate communicates with each injection device, and the number is not limited even when a plurality of gates are provided. The position of such a gate is appropriately set depending on the shape of the container to be obtained. For example, in the case of obtaining a substantially symmetrical container, the gates of the resin of each color are connected to the merging line of the two colors. It is preferable that they are provided substantially line-symmetrically to the left and right.

The injection device may be a screw type or a plunger type as described above. In the above-described manifold member 60, two resin inlets 80a and 80b and two resin supply ports 13a and 13b are shown. However, in the case of single-color molding, the manifold member 6 is used.
3A, one resin inlet 80c into which a kind of resin injected from one heating cylinder 14a (or 14b) flows, and one resin inlet 80c from the one resin inlet 80c. What is necessary is just to use the one in which the branch passage 82c is formed so that the sucked (inflow) resin can be divided into the two resin supply ports 13a and 13b. Such a manifold member 60 and the manifold member 60a can be easily replaced by removing a fixing member (not shown) for joining and fixing the heating cylinders 14a, 14b and the manifold 60 (60a).

When the resin inlet (supply port) of the auxiliary block is singular (not shown), a manifold member 60b as shown in FIG. 3B can be used. Two resin inlets 80a, 80b into which the resin injected from the two heating cylinders 14a, 14b that inject the same type of resin, and one resin sucked (inflow) from the resin inlets 80a, 80b. A resin passage which can be joined to the resin supply port 13c is formed.

In order to integrally mold the two-color container 1 using the above-described injection molding apparatus, the two-color container 1 is first melted separately,
Heating cylinders 14a and 14b are formed by operating the screws (not shown) in the injection devices 15a and 15b, respectively, with resins colored in different colors as described below.
The nozzles 13a, 13b provided substantially at the center of the manifold member 60 disposed at the resin injection port of the above-described resin injection port inject the resin into the in-mold passages 12a, 12b. The resin injected into the mold flows into the runners 11a and 11b from the passages 12a and 12b provided substantially in the center of the auxiliary block 18, and is pressed into the cavity 10 through the gates 16a, 16a, 16b and 16b. Is done. In this way, the two-color resin press-fitted into the cavity 10 is joined at the center of the bottom plate 3 in the left-right direction in the cavity 10 to form a merging line L, and the supply (filling) of the resin is completed. The desired two-color container 1 is formed.

When the container 1 is viewed from the back side of the bottom plate, the merging line L may be formed leftward or rightward of the container 1 which is color-coded left and right. The two-color container 1 obtained after the completion of the injection molding is taken out by moving the movable mold 8 after an appropriate cooling time.

The two-colored thermoplastic resin used for integrally molding such a two-colored container 1 usually contains a thermoplastic resin and a pigment (dye). I have.

As the thermoplastic resin, a resin which is generally widely used in injection molding of plastic is used without any particular limitation. Examples include polypropylene (PP), polyethylene (PE), ABS resin, polystyrene (PS), polycarbonate (PC), polyvinyl acetate (EVA resin), polyamide (PA), and polyacetal (POM).

The thermoplastic resins to be charged into the injection devices 15a and 15b are different in color, that is, different only in pigment (dye) or composition ratio thereof, and it is preferable to use the same resin.

As the pigment to be mixed with the resin, pigments or dyes generally used for coloring plastics are used without any particular limitation. Further, the thermoplastic resin, depending on the intended use of the resulting container,
Additives such as heat stabilizers and weather stabilizers, and fillers such as glass fibers and fillers are appropriately blended.

In general, such a thermoplastic resin is injection-molded under conditions such as a melting temperature and a pressure at the time of injection-molding a plastic. In the present invention, as described above, injection is performed from different directions. The injection is performed while adjusting the injection pressure and the like such that the melted resin merges at a desired position, generally at the center of the cavity 10.

According to the present embodiment, since the injection molding apparatus having the above-described manifold 60 is used, the size of the mold 100 is smaller than the size of the heating cylinders 14a and 14b.
Even if is small, the two-color container can be integrally molded by arranging the two cylinders substantially in parallel without arranging them so as to intersect on the extension line as shown in FIG.

When the single-color molding is performed using the same mold after the two-color molding of the container is performed in this manner, the manifold member 60 is connected to the heating cylinder 14a,
14b, loosen the bolts (not shown), remove the manifold member 60, and remove the manifold member 6
0, the manifold member 60a for a single color shown in FIG.
You only need to attach. Further, by removing the manifold 60, the two heating cylinders 14a and 14b are arranged obliquely with respect to the movable direction of the mold using the mold shown in FIG. It can also be molded.

At the time of such an operation, it is not necessary to disassemble the mold, so that the operation of replacing the manifold is extremely easy. As mentioned above, although one Example of this invention was described, this invention is not limited to said Example, Various modifications are possible based on the technical idea of this invention.

For example, in the above embodiments, the two-color container has been described as an example, but the present invention can be applied to various two-color molded articles. Further, in the two-color container, for example, a plurality of holes for draining water may be provided in the bottom plate portion.

[0040]

As described above, according to the method for integrally forming a two-color container according to the present invention, the manifold is provided at the injection port of the cylinder disposed substantially in parallel.
In addition, since the end face of the runner block is disposed so as to face the nozzle at the tip of the manifold, the connection with the nozzle is good. Therefore, the flow of the resin is improved. Also,
When performing single-color molding, the manifold provided with the nozzles can be detached from the cylinder and easily replaced with a single-color one. Since this replacement work can be performed on the injection machine side without disassembling the mold, workability is extremely good.

[Brief description of the drawings]

FIG. 1 is a perspective view of a two-color container obtained by the present invention.

FIG. 2 is a vertical sectional view of an injection molding apparatus provided with a manifold member used in the present invention.

FIG. 3 is a longitudinal sectional view of a single color manifold member used in another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of an injection molding apparatus used in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Two-color container, 3 ... Bottom plate part, 8 ... Movable mold, 9 ... Fixed mold, 10 ... Cavity, 11 ... Runner block, 11a, 11b, 12a, 12b, 82a, 82b ... Resin passage, 13a, 13b ... Manifold nozzle, 14a, 14b ... Cylinder, 15a, 15b ... Injection device, 16a, 16b ... Gate, 18 ... Auxiliary block of runner block, 50a, 50b ... Heating cylinder resin injection port, 60, 60a, 60b ... Manifold Member: 62: Nozzle part, 80a, 80b: Resin suction port (inlet) of manifold, 100: Mold.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/16 B29C 45/13 B29C 45/14

Claims (4)

(57) [Claims] 1. Heating cylinders for individually melting thermoplastic resins colored differently from each other are provided, and resins of different colors injected from these heating cylinders are guided to a mold runner. In a two-color molding method for a plastic product in which these resins are supplied to a cavity and the resins are merged and integrally molded in the cavity, the heating cylinders are arranged so as to be substantially parallel to each other. The heating cylinder is provided with a detachable manifold member, and the manifold member is provided with a resin receiving port at a position corresponding to an injection port of the heating cylinder, and is provided on the runner of a mold. A resin injection port is provided at a position corresponding to the provided resin reception port, and a resin passage communicating the resin reception port with the resin injection port is provided. A two-color molding method for a plastic product, characterized by using an injection molding device. 2. The manifold member is provided with two resin passages that communicate the resin receiving port and the resin injection port, and the two resin passages are formed in a mold rather than a cylinder side. The two-color molding method according to claim 1, wherein an injection molding device formed close to the runner side is used. 3. A heating apparatus comprising two heating cylinders for melting the thermoplastic resin separately, guiding the resin injected from these heating cylinders to a mold runner, and supplying these resins to the cavities from the runner; In a plastic product molding apparatus in which these resins are merged and integrally molded in the cavity, the heating cylinder is disposed so as to be substantially parallel, and the heating cylinder is detachably mounted on the manifold. The manifold member is provided with a resin receiving port at a position corresponding to the injection port of the heating cylinder, and a resin injection port at a position corresponding to the resin receiving port provided on the runner of the mold. And a resin passage communicating between the resin receiving port and the resin injection port is provided. Place. 4. The manifold member is provided with two resin passages which communicate the resin receiving port and the resin injection port, and these two resin passages are formed in a mold rather than a cylinder side. The injection molding apparatus according to claim 3, wherein the injection molding apparatus is formed close to the runner side.