JPH04201537A - Multi-stage apparatus for extruding molten resin - Google Patents

Abstract

PURPOSE:To obviate the dispersion of molten resin temperature and cool it at a uniform temperature quickly by piping a plurality of resin pipes divided from molten resin extruded from a first extruding machine in a transferring pipe, and forming medium passages through which a heat-change medium runs, outside respective resin pipes. CONSTITUTION:Molten resin D extruded from the extrusion port G of a first extruding machine A is dividingly flowed into a plurality of resin pipes 3 provided in a transferring pipe K. For this reason, the cross-sectional area of the molten resin running in respective resin pipe 3 is small, and thus the flow quantity thereof also becomes small. Since, coolant S is flowed into medium passages 4 formed outside respective pipes 3, the molten resin D in respective resin pipes 3 is swiftly cooled without dispersing the temperature.

Description

[Detailed description of the invention] [Industrial application field]

The multi-stage molten resin extrusion apparatus of the present invention is used, for example, to extrude and coat the outer periphery of a core wire with resin when manufacturing a crosslinked polyethylene insulated cable.

[Conventional technology]

Conventionally, when manufacturing a crosslinked polyethylene insulated cable, for example, the following method is used. As shown in Fig. 4, the pellet-shaped resin material C supplied to the hopper B of the first extruder A is heated to an appropriate temperature and melted, and an anti-aging agent with a melting point of 170°C is added to the molten resin. E
This molten P4 fat is passed through the screen pack J set on the breaker plate H on the side of the extrusion port G to eliminate foreign matter mixed in the molten resin. remove. At this time, if the temperature of the molten resin is low, the anti-aging agent E will not melt sufficiently, so the anti-aging agent E cannot be uniformly kneaded into the molten resin. Since the mesh is as fine as 100 to 500 meshes, the resistance when passing through the screen back J made of molten resin is large, and if the temperature becomes extremely low, there is a risk that the screen back J will be torn due to the resistance. Therefore, 1. Usually, the temperature of the molten resin in the first extrusion 11A is about 17
It is set to a high temperature of about 0°C. This molten resin passes through the transfer conduit shown in Fig. 4 and is supplied to the supply port M of the second extruder, where a crosslinking agent N is injected into the molten resin. It is elaborated. It is then supplied to a crosshead P, where the outer periphery of the core wire Q is coated by extrusion, thereby completing a crosslinked polyethylene insulated cable. At this time, if the temperature of the molten resin remains at about 170°C, the molten resin is likely to burn when the crosslinking agent N is injected, so the molten resin is supplied to the second extruder. It is necessary to lower the temperature of the molten resin to below about 135° C. before it is heated. Therefore, conventionally, as shown in Fig. 4, a heat exchange medium (refrigerant) S is passed through a refrigerant passage R provided on the outer periphery of the transfer pipe through which the molten resin passes, and the entire molten resin is extruded. was forcibly cooled from the outside. By the way, the resin without the crosslinking agent has a temperature of 170°C.
Although there is no need to worry about burning, the molten resin becomes too soft and it becomes difficult to extrude and coat the outer periphery of the core wire with a uniform thickness, which tends to cause uneven thickness.

[Problem to be solved by the invention]

However, in the conventional extrusion coating method, the refrigerant passage S is provided only at the outermost periphery of the transfer pipe, so in order to sufficiently cool the molten resin passing through the center of the transfer pipe, the refrigerant S However, if the temperature is lowered too much, the molten resin on the outside of the transfer pipe will solidify, which is a difficult problem. To solve this difficult problem, the temperature of the refrigerant S should be set relatively high, and the length of the transfer pipe should be increased so that the molten resin is gradually cooled by the refrigerant S while passing through it. do it. However, if this is done, a problem arises in that the entire multi-stage molten resin extrusion apparatus becomes larger.

[Purpose of the invention]

An object of the present invention is to provide a multi-stage molten resin extrusion device that can quickly cool the molten resin to a uniform temperature by eliminating variations in the temperature of the molten resin in a transfer pipe to be cooled, and that can miniaturize the entire device. Our goal is to provide the following.

[Means to solve the problem]

As shown in FIGS. 1 to 3, the multistage molten resin extrusion apparatus of the present invention is configured to transfer molten resin extruded from a first extruder A to a second extruder through a transfer pipe K. In the multi-stage molten resin extrusion apparatus, the molten resin extruded from the first extruder A branches and flows into the transfer pipe. ! Several resin pipes 3 are arranged, and each resin pipe 3
It is characterized in that a refrigerant flow path 4 through which the refrigerant S flows is formed on the outside of the refrigerant.

[Effect]

In the multi-stage molten resin extrusion apparatus of the present invention, as shown in FIGS. Since the flow is divided into the resin pipes 3, the film area of the molten resin flowing inside each resin pipe 3 is small and the flow rate is also small. Since the refrigerant S is flowing, the molten resin in each resin pipe line 3 is quickly cooled without variations in temperature.

【Example】

1 to 3 show an embodiment of the multi-stage molten resin extrusion apparatus of the present invention. In Figure 1, A is the first extrusion beak, C is the hopper of extruder A, C is the pelletized resin material supplied to hopper B, D is the melted resin, and F is the extruder A. Scrier in the -th extrusion WkA, G is the extrusion port of the same extrusion 11A, H
is the same extrusion exit GfII! 4 is a breaker plate, J is a screen back set on the breaker plate H, E is an anti-aging agent to be kneaded into the molten resin, and T is a pump for supplying the anti-aging agent E. It is. In addition, L is the second extruder, M is the supply port of the extruder,
N is the crosslinking agent injected into the extruder, U is the crosslinking agent N
P is a pump for injecting the extruder, P is a crosshead to which the extruded molten resin is supplied, and Q is a core wire coated with the molten resin. These may be existing ones or ones improved for the present invention. K shown in FIGS. 1 to 3 connects the first extruder 11A and the second extruder, and connects the extrusion port G of the first extruder 11A.
The molten resin extruded from the second extrusion ring supply port M
This is a transfer pipe for transferring to. A refrigerant supply pipe 10 and a refrigerant discharge pipe 11 connected to the refrigerant circulation f1 device 12 are attached to this transfer pipe K, and as shown in FIGS. 2 and 3, the outside of the refrigerant supply pipe 1O is on one side of the occlusion plate
is attached, and the other closing plate 2 is attached to the outside of the refrigerant discharge pipe 11. 3 shown in Figures 2 and 3 are the two blocking plates 1.21'
There are a plurality of resin pipes extending through the transfer pipe, through which the molten resin extruded into the transfer pipe branches and flows. As this resin conduit 3, a vibrator or the like having an inner diameter of about 1/3 to 1150 of the inner diameter of the cylinder of the extruder and a wall thickness of about 1/3 to 1150 of the inner diameter of the cylinder of the extruder is used. Thirty-seven vibrators made of gold with a diameter of 12 mm and a wall thickness of 2 mm were used. 1! 4 shown in Figures 2 and 3 is a refrigerant flow path formed on the outside of the resin pipe 3, specifically, the area between the outer periphery of the resin pipe 3 and the inner periphery of the transfer pipe. is formed between. This is for cooling the molten resin passing through the P4 fat pipe line 3 through the flow of the refrigerant S supplied from the refrigerant supply pipe IO, and the refrigerant S is discharged from the refrigerant discharge pipe 11. It should be drained. The dimensions and cooling performance of the multi-stage molten resin extrusion apparatus of this example and the multi-stage molten resin extrusion apparatus of FIG. 4 are shown in the table below. As is clear from this table, in order to obtain the same cooling temperature, in the conventional extrusion device, the length of the transfer pipe is 150 mm.
0 mm, whereas the extrusion device of the present invention only had a diameter of 4 mm.
00 mm, making it possible to downsize the entire multi-stage molten resin extrusion device. In this example, only the case where the molten resin was cooled was described in detail, but the multi-stage molten resin extrusion apparatus of the present invention cools the molten resin extruded from the first extruder A, for example. It can also be used for heating before being supplied to the machine, in which case a heat medium may be used as a heat exchange medium instead of the refrigerant S, and there are no particular limitations on its use. do not have.

【Effect of the invention】

In the multi-stage molten resin extrusion apparatus of the present invention, the first extruder A
The molten resin extruded from the resin pipes 3 is divided into a plurality of resin pipes 3, and is cooled by the refrigerant S flowing outside each resin pipe 3, so that the molten resin in each resin pipe 3 is Therefore, the length of the transfer pipe can be shortened, and the entire multistage molten resin extrusion apparatus can be downsized.

[Brief Description of the Drawings] Fig. 1 is an overall structural diagram showing one embodiment of a multi-stage molten resin extrusion device of the present invention, Fig. 2 is a partial cross-sectional perspective view of a transfer pipe portion of the same device, and Fig. 3 The figure is a detailed view of two parts of FIG. 1, and FIG. 4 is an overall structural diagram showing an example of a conventional multi-stage molten resin extrusion apparatus. 3 is the resin pipe line 4 is the medium flow path (refrigerant flow path) A is the first extruder is the transfer pipe for the molten resin is the second extruder S is the heat exchange medium (refrigerant) Figure 3 v , 2 fig.

Claims (1)

[Claims] In a multi-stage molten resin extrusion device in which molten resin extruded from a first extruder is transferred to a second extruder through a transfer pipe, the molten resin extruded from the first extruder is transferred into the transfer pipe. 1. A multi-stage molten resin extrusion device, characterized in that a plurality of resin pipes are arranged through which the molten resin branches and flows, and a medium flow path through which a heat exchange medium flows is formed outside each of the resin pipes.