JP2003145576A - Molding processing method for thermoplastic resin and molding apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding processing method for a thermoplastic resin having good productivity taking no time in heat cycle molding, and a molding apparatus therefor. SOLUTION: A core mold 1 is made of concrete and heat radiating and absorbing pipes 15 are parallelly embedded in the core mold 1 at an equal interval in the vicinity of the mold surface of the core mold 1. A cavity mold is a metallized concrete mold and a nickel metal layer is laid on the mold surface thereof. The heat radiating and absorbing pipes 15 on the side of the cavity mold are embedded in the back surface of the metal layer at an equal interval. A heating medium, for example, high temperature water is introduced into the heat radiating and absorbing pipes 15 of the core mold 1 from a heating medium supply tank 11 and, in the same way, high temperature water is introduced into the heat radiating and absorbing pipes 15 in the cavity mold. The high temperature water flows through the parallel heat radiating and absorbing pipes 15 parallelly to raise the temperatures of the molds to a predetermined temperature. Subsequently, the thermoplastic resin and a skin layer material are injected in the mold space to fill the mold space. After the completion of filling, cooling water is injected through the same pipelines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin molding method and a thermoplastic resin molding apparatus, and more particularly to heating and cooling techniques by heat cycle molding.

[0002]

2. Description of the Related Art When a molded product is made of a thermoplastic resin,
A mold with a given shape is used. Mold molding requires that the temperature of the mold be kept constant, and that hot water heated to a constant temperature be passed through the mold. In addition, after the molding resin is cured, it is necessary to cool the mold in order to shorten the molding cycle. The molded product thus obtained is further subjected to texture transfer with a skin layer on the surface. There is also a method of simultaneously performing molding and transfer. When these are performed simultaneously, strict temperature control of the mold is required during molding. In this way, the technique of molding while controlling the temperature of heating and cooling is called heat cycle molding method.Typically, a heat-radiating tube is embedded in the mold to mold the mold so that the temperature can be freely controlled. To do. The endothermic tube used in such heat cycle molding controls heat transfer and is indispensable for delaying the cooling of the molding resin until the molding resin is completely filled in the mold space. In heat cycle molding, a molded product that has been commercialized by conventional coating can be coated free, and a skin layer can be simultaneously molded on the surface of the molded resin. As described above, even when the skin layer is formed on the surface of the resin molded product, the skin layer molding time is virtually unnecessary. Moreover, there is an advantage that high-quality grain transfer can be obtained.

Here, in the heat cycle molding described above, a state in which the skin layer 3 and the thermoplastic resin 4 are injected from the injection machine 4a into the mold space between the core mold 1 and the cavity mold 2. Are shown in FIGS. FIG. 5 shows the type heat cycle molding method, and FIG. 6 shows the normal injection (INJ) molding method. In the type heat cycle molding method, the thermoplastic resin 4 is injected while forming the skin layer 3 on only one surface. In the usual injection molding method, injection is performed while forming the skin layers 3 on both surfaces. In both cases, the mold temperature is controlled to form the skin layer 3.

FIG. 7 shows the arrangement of the heat radiating and absorbing tubes of a molding apparatus conventionally used for heat cycle molding.
As shown in FIG. 7, the heat dissipation pipes 15 are embedded in parallel in both the core mold 1 and the mold mold 2. The pipes embedded in parallel are formed by connecting both ends of adjacent pipes with U-shaped pipes or the like to form a series passage as a whole, so to speak, a flow passage that flows in a single stroke. The base end portion of the heat dissipation pipe 15 is joined to the confluence pipe joint 13 provided with an inlet passage switching valve, and the heating medium supply tank 11 and the cooling medium supply tank 12 are joined together.
The discharge pipes from both of the above are joined to this joining pipe joint 13. The heating medium discharged from the heating medium supply tank 11 is, for example, high temperature water, steam or high temperature gas, and the cooling medium discharged from the cooling medium supply tank 12 is, for example, cooling water. These heating medium and cooling medium,
Through the confluent pipe joint 13 provided with an inlet passage switching valve, the heat radiating and absorbing pipes 15 alternately flow in a predetermined time cycle.

[0005]

FIG. 8 shows how the temperature changes when molding the core mold 1 and the mold mold 2 while controlling the temperature of the core mold 1 and the mold mold 2 with the heat dissipation tube 15 using the conventional heat cycle molding apparatus described above. Is shown. In one cycle of molding, first, the heating medium is discharged from the heating medium supply tank 11, and the core mold 1 and the cavity mold 2 are respectively heated via the heat dissipation pipe 15. In this case, since the heat sink tube 15 meanders in the mold from the upstream side to the descending side and is arranged in the series path, the temperature rising time t1 is required until the mold on the downstream side reaches a predetermined set temperature. . Then, after a lapse of a predetermined molding process, the process proceeds to a cooling process. Similarly, a cooling time t is reached until the downstream side of the heat-dissipating and absorbing tube 15 arranged in the series passage is cooled to a predetermined temperature.
2 is required.

As described above, in the conventional heat cycle molding, the temperature is raised in a gentle curve for each cycle in the conventional heat-up time t1, and after a predetermined molding time elapses, the temperature is lowered in a gentle curve for the cooling time t2. While doing the molding work. As described above, the conventional heat cycle molding method has various advantages, but the temperature rising / falling curve is gentle, and it takes time to stabilize the temperature balance of the entire mold due to the pressure loss in the pipe of the heat dissipation pipe 15. Therefore, there is a problem that it takes a long time to perform one cycle of molding from the start to the end.

Therefore, it is an object of the present invention to provide a thermoplastic resin molding processing method and molding apparatus which can significantly shorten the molding time in heat cycle molding and have good productivity.

[0008]

In order to achieve the above object, the present invention according to claim 1 uses a mold in which a plurality of heat-dissipating tubes for temperature control are embedded and uses a thermoplastic resin in the space inside the mold. And a skin layer material are injected at the same time and then cooled to form a molded product in which the skin layer covers the surface. It is characterized by controlling the temperature of the space inside the mold. In this case, the mold is preferably a metalized concrete mold in which a nickel metal layer is laid on the mold surface, the heat sink tube is embedded along the back surface of the nickel metal layer, and the upstream side of the core mold is a mold type. The downstream side of the core mold is set to match the downstream side, and the downstream side of the core mold is set to match the upstream side of the cavity mold.

Further, the invention according to claim 3 is a molding apparatus including a thermoplastic resin molding die for molding a molded product having a surface coated with a skin layer by simultaneously injecting a thermoplastic resin and a skin layer material. The heat-dissipating pipe is embedded in the mold, and the heat-dissipating pipe constitutes a parallel path. In this case, the mold is preferably a metalized concrete mold in which a nickel metal layer is laid on the mold surface, the heat dissipation tube is embedded along the back surface of the nickel metal layer, and the upstream side of the core mold is the downstream side of the mold type. The core type is arranged so that the downstream side thereof is aligned with the upstream side of the mold type.

According to the present invention, in the case of the molding method or molding apparatus in which the buried heat sink tubes are assembled in parallel paths, the number of buried tubes is multiplied as compared with the conventional case in which the heating fluid or the cooling fluid is circulated in the serial path. It is possible to circulate more heating medium in a short time in the combined amount. As a result, a large amount of heat can be transferred in a short time, so that the molding time can be significantly shortened.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a conceptual diagram of a molding apparatus by a heat cycle molding method for a thermoplastic resin according to an embodiment of the present invention. This molding apparatus, like the conventional apparatus shown in FIGS. 5 and 6, has a mating mold composed of a core mold 1 and a cavity mold 2, and a skin is provided in a predetermined space set when the molds are mated. Layer 3
And the thermoplastic resin 4 are injected from the injection machine 4a to form a predetermined molded product.

As shown in FIG. 1, a plurality of heat radiating / absorbing tubes 15, four heat radiating / absorbing tubes in the illustrated example, are inserted into one of the molding dies from one end of the mold and pierce the other end of the dies, respectively. It is embedded in a mold in parallel at predetermined intervals. In FIG. 1, the heat sink tube 15 arranged in the core mold 1 is shown.
Similarly, a plurality of heat radiation and absorption tubes 15 are arranged in parallel at predetermined intervals. On the base end side, that is, on the upstream side, the heat-radiating heat-absorbing pipes 15 are exposed to the outside of the mold and communicate with each other via a multi-way branch pipe joint 14, and are drawn out from the multi-way branch pipe joint 14. It is joined to a merging pipe joint 13 provided with a passage switching valve, and is connected to a heating medium supply tank 11 and a cooling medium supply tank 12. Further, on the tip end side of the heat dissipation pipe 15, that is, on the downstream side, the heat dissipation pipe 15 is exposed to the outside of the mold, and the drain tank 1 is exposed there.
Directly connected to 6 in parallel. That is, in the present embodiment, a large number of heat-dissipating pipes 15 are extended in parallel at substantially equal intervals over the entire length of the core mold 1 via the multi-way branch pipe joint 14, and each of them has an arrow in the mold of the core mold 1. It extends parallel to the direction shown by and is arranged in parallel with and directly communicates with the drain tank 16. Similarly, in the cabinet type 2 as well, the heat radiation and absorption tubes 15 extend in parallel and in parallel, and the drain tank 16
Are connected to. The heating medium discharged from the heating medium supply tank 11 is, for example, high temperature water, steam or high temperature gas, and the cooling medium discharged from the cooling medium supply tank 12 is, for example, cooling water. The heating medium and the cooling medium alternately flow through the heat-releasing heat-absorbing pipe 15 in a predetermined time cycle via the confluent pipe joint 13 provided with an inlet passage switching valve.

2 and 3 are sectional views of a mold in which the heat-dissipating and absorbing tube 15 is embedded. 2 is a cross-sectional view taken along the radial direction of the heat dissipation pipe 15, and FIG. 3 is a cross-sectional view taken along the line AA of the mold 2 in FIG. In FIG. 2, the core mold 1 and the cavity mold 2 are connected to each other with a mold space 17 having a predetermined width interposed therebetween. In the present embodiment, the core mold 1 is made of concrete, and the heat radiating tubes 15 are embedded in parallel near the mold surface at equal intervals. The mold 2 is also made of concrete, and uses a metalized concrete mold (MCM) in which a nickel metal layer 18 having a thickness of 5 to 8 mm is laid on the mold surface. On the back surface of the metal layer 18, the heat radiating and absorbing tube 15 on the side of the mold 2 is in the same surface direction as the heat radiating and absorbing tube 15 on the side of the core type 1, and along the back surface of the nickel metal layer 18 as shown in FIG. It is embedded in concrete at intervals. In FIG. 2, in the core mold 1, a heating medium such as high-temperature gas or hot water and a cooling medium such as cooling water flow from the front side of the paper to the back of the paper, and in the mold cavity 2 flow in the opposite direction from the back of the paper toward the front of the paper. ing. As a result, the upstream side of the core type matches the downstream side of the cavity type, and the downstream side of the core type matches the upstream side of the cavity type. Of course, the heating medium and the cooling medium that pass through the heat releasing and absorbing tubes 15 of the core type 1 and the cavity type 2 may be made to flow so that the upstream side and the downstream side coincide with each other.

The heat cycle molding apparatus is used, for example, as follows. A high-temperature heating medium is introduced from the heating medium supply tank 11 shown in FIG. 1 into the heat radiating / absorbing tube 15 of the core mold 1, and similarly introduced into the heat radiating / absorbing tube 15 in the mold 2, and the mold space 17 shown in FIG. The inside is brought to a uniform high temperature state in a short time. While maintaining the high temperature state, the mold space 17 is injected and filled with the thermoplastic resin and the skin layer material from the injection machine. When the filling is completed, the heating medium is discharged to the drain tank 16, the junction pipe joint 13 with an inlet passage switching valve is operated to switch the inlet passage, and low temperature water is injected from the cooling medium supply tank 12 for a short time. The temperature of the mold space 17 is lowered and the thermoplastic resin is cooled. In this case, since the plurality of heat-release pipes 15 are connected in parallel to the heating medium supply tank 11, the flow paths of the heat-release pipes 15 are short, so that the mold is set to a predetermined temperature over the entire area of the mold. It can be heated uniformly at high temperature. When the mold is cooled after the molding, it can be cooled at a uniform low temperature.

Further, as shown in FIG. 2, the mold 2 uses a metalized concrete mold in which a nickel metal layer 18 is laid, and when the heat dissipation pipe 15 is embedded in the back surface of the nickel metal layer 18, Since the heat transfer distance to the nickel metal layer 18 becomes short and the nickel metal layer 18 has a high heat transfer property, the mold space 17 is rapidly heated and rapidly cooled. Further, although the mold 2 and the core mold 1 are joined at the time of molding, the flow path that flows through the core mold 1 does not pass through the mold mold 2, and the flow path that flows inside the mold 2 is also the core mold. Do not pass through 1. Therefore, the heat dissipation pipe 1 in the mold
Since the length of 5 is the same in the core mold 1 and the mold mold 2, the hydrodynamic pressure is the same, and the heat transfer is performed in a well-balanced and uniform manner.
As described above, according to the present invention, since the heat dissipation pipes 15 are connected in parallel without being connected in series, the temperature in the mold space 17 is not unevenly distributed between the mold surface and the core surface, and heat is evenly distributed. You will be able to move.

FIG. 4 shows a graph of the temperature change according to the present invention. In one cycle of the molding process, first, the heating medium is discharged from the heating medium supply tank 11,
The temperature of the entire core mold 1 and the mold mold 2 is raised via the heat dissipation pipe 15. In this case, since the heat dissipation pipes 15 branch from the heating medium supply tank 11 and a plurality of heat dissipation pipes 15 are arranged in parallel at equal intervals, the length of each heat dissipation pipe 15 in the mold is extremely short. Therefore, the heat is quickly transferred from the upstream side to the descending side of each heat-dissipating pipe 15, and the entire mold reaches a predetermined set temperature in an extremely short heating time t3. Then, after the lapse of a predetermined molding process, the heat-radiating and absorbing tubes 15 arranged in parallel in the cooling process.
Similarly, when a cooling medium is flown in, an extremely short cooling time t4
The entire mold is cooled to a predetermined temperature by. Therefore, compared with the conventional molding process shown in FIG. 8, the temperature rise time is t3 <t.
1. According to the present invention, the temperature is lowered at a steep angle and the temperature is lowered at a steep angle, and one cycle process is completed in a short time, for example, half or less of that of the conventional apparatus.

As shown in FIG. 2, when a metalized concrete mold in which a nickel metal layer is laid on the mold surface is used, the nickel metal layer has a high heat transfer rate and can be made thin, so that the heat dissipation tube The heat can be sent to the mold space in a short time with almost no loss. Therefore, by connecting the heat-dissipating pipes in parallel according to the present invention, the temperature rise and the temperature fall can be controlled in an extremely short time, and the molding time can be further shortened. In addition, if the upstream side of the core mold is aligned with the downstream side of the mold mold, it is possible to manage the mold space uniformly and in good balance without temperature deviation.

[0018]

Since the present invention has the above-mentioned structure,
Since a large amount of heat can be transferred in a short time, in heat cycle molding, a molding operation can be performed in an extremely short time, and a thermoplastic resin molding processing method and a molding device with good productivity can be provided. .

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a thermoplastic resin molding apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a cab type in which a heat radiating and absorbing tube according to an embodiment of the present invention is embedded.

FIG. 3 is a cabinet type in which a heat-dissipating heat-absorbing tube is embedded, AA in FIG.
It is sectional drawing which follows the line.

FIG. 4 is a graph showing a temperature change in a mold space according to the present invention.

FIG. 5 is a cross-sectional view showing how a skin layer and a thermoplastic resin are injected by a heat cycle molding method.

FIG. 6 is a cross-sectional view showing how a skin layer and a thermoplastic resin are injected by a normal injection molding method.

FIG. 7 is a conceptual diagram of a conventional thermoplastic resin heat cycle molding apparatus.

8 is a graph showing a temperature change in a mold space at the time of molding using the molding apparatus of FIG.

[Explanation of symbols]

1 core type 2 cabinet type 3 skin layers 4 Thermoplastic resin 11 Heating medium supply tank 12 Coolant supply tank 13 Joint pipe joint 14 Multi-way branch pipe joint 15 Endothermic tube 16 drain tank 17 type space

Claims (4)

[Claims] 1. A mold in which a plurality of heat-dissipating tubes for temperature control are embedded is used, and a thermoplastic resin and a skin layer material are simultaneously injected into a temperature-controlled internal space of the mold and then cooled, and the surface is covered with the skin layer. In the method of molding a thermoplastic resin for molding a molded article coated with, a thermoplastic resin characterized by controlling the temperature in the mold space during molding by circulating a heating medium in a parallel path through the heat-dissipating pipe. Molding processing method. 2. The mold is a metalized concrete mold in which a nickel metal layer is laid on the mold surface, the heat dissipation pipe is buried along the back surface of the nickel metal layer, and the upstream side of the core mold is downstream of the cavity mold. The thermoplastic material molding method according to claim 1, characterized in that the downstream side of the core mold is aligned with the upstream side of the cavity mold according to the side. 3. A molding apparatus including a thermoplastic resin molding die for molding a molded article whose surface is covered with a skin layer by simultaneously injecting a thermoplastic resin and a skin layer material, wherein a heat-radiating tube is provided in the mold. The thermoplastic resin molding apparatus is characterized in that it is embedded and that the heat-radiating tube forms a parallel path. 4. The mold is a metalized concrete mold in which a nickel metal layer is laid on the mold surface, the heat sink tube is buried along the back surface of the nickel metal layer, and the upstream side of the core mold is downstream of the cavity mold. 5. The molding apparatus for a thermoplastic material according to claim 4, wherein the downstream side of the core mold is aligned with the upstream side of the cavity mold.