JPS5928007B2 - Seizou Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing a foamed plastic insulated electric wire, and more particularly to a cooling apparatus for high-speed extrusion of the electric wire.

For example, in a multi-pair cable made of foam insulated wires in which the conductor is coated with a foam (glass insulation) layer, unbalanced capacitance between lines causes crosstalk.

Therefore, even in the individual wires that make up the cable,
This variation in capacitance poses a problem when extruding and covering the center conductor with a foamed insulator. FIG. 1 is a capacitance C chart model diagrammatically showing variations in capacitance of a conventional electric wire. Generally, two factors are superimposed on variations in capacitance in such foamed plastic electric wires and the like. That is, one is the temperature change of the coating resin, and the other is the fluctuation of the cooling hardening start position (cooling point) of the extruded coating resin due to cooling water, line runout, etc. Changes in the resin temperature appear as long-period waves as shown in FIG. 1, and cooling point fluctuations, line vibrations, etc. appear as instantaneous disturbances superimposed on the long-period waves. In order to control long-period waves, the screw rotation speed of the extruder (i.e., the feeding rate of the coating resin material) is adjusted based on the measurement value from the C (capacitance) measuring device or the outer diameter measuring device of the electric wire. It is known to control the drawing speed of the wire, the resin temperature of the extruder, or to control the position of the cooling water tank by using a moving water tank.

However, although cooling point fluctuations seem to be the main cause of the instantaneous turbulence, no active measures have been taken to date to address this.

Moreover, as a recent trend, the take-up speed of this foam-insulated electric wire is also increasing. like this"
In "high-speed extrusion," a velocity gradient is created in the artificial part of the cooling water tank due to the viscosity of flowing water drawn by a moving electric wire in the cooling water tank, and this velocity gradient is difficult to maintain a constant shape. Therefore, the cooling point fluctuates and the capacitance is greatly disturbed. Furthermore, air suction generated at the inlet of the cooling water tank generates bubbles, and the shape of the bubbles also changes from time to time. Therefore, as the cooling point changes, the capacitance further changes. Further, if the C chart model has the same waveform at high speed and low speed, the difference in the manufacturing length per unit time will result in the production of a longer electric wire with a larger C deviation, resulting in a reduction in quality. Therefore, when manufacturing electric wires using a high-speed extruder, there is a need for an apparatus for manufacturing foamed plastic electric wires that can further prevent fluctuations in the cooling point and air suction. Therefore, the main purpose of this invention is to
It is an object of the present invention to provide a relatively high-speed extrusion device for producing an insulated wire that can satisfy the above-mentioned demands.

In summary, this invention uses a pressurized (moving) water tank as the cooling water tank following the extruder, thereby preventing velocity gradients and air suction as described above, and furthermore, keeping the torrent of cooling water constant due to the pressurization. This is a manufacturing device equipped with a means for preventing this at a certain position. The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings. FIG. 2 is an illustrative diagram showing the configuration of a preferred embodiment of the present invention.

In the structure, an extruder 1 coats the entire outer periphery of the conductor 21 with a foamable plastic insulation coating layer 22 in a high temperature melted and softened state.
is formed. This extruded electric wire 20 passes through a cooling water tank 300 whose longitudinal cross section is shown in this figure, the coating layer 22 is hardened, and is taken off by a taking-off device (not shown) and wound up one after another. go. The cooling water tank 3
00 is movable in its longitudinal direction at its lower part by a moving drive system 4 including, for example, a servo motor. That is, this cooling water tank 300 is configured as a mobile cooling water tank. The capacitance of the electric wire 20 exiting the cooling water tank 300 is detected by a capacitance measuring device 7 included in a cooling water tank (not shown) Vc disposed at a subsequent stage.

This capacitance value from the measuring device 1 is given to the setting control circuit 8. The setting control circuit 8 controls the input electric wire 20
The movable drive system 4 is controlled based on the deviation between the capacitance value and the preset capacitance value, and the cooling water tank 3 is controlled accordingly.
This is to control the movement (position) of 00. The internal cavity defined by the housing 301 of the cooling water tank 300 is continuously supplied and filled with cooling water 6.

For this purpose, a cooling water supply port 302 for pressurized injection of the cooling water 6 is formed in the upper part of the housing 301, and a cooling water source (not shown) is connected to this supply port 302. ... Side walls 304, 30r are further formed integrally with the housing 301 at the lower part of the outside of one (left side in the figure) side wall of the housing 301. One side wall and side wall 304 of this one housing 301
The distance between the two and the distance between the side walls 304 and 307 are both used as felt insertion grooves 305 and 306 whose width is selected so that felts 51 and 52, which will be described later, can be inserted closely. The lower (bottom) FlC of the felt insertion grooves 305 and 306 flow out from the housing 301 to the felts 51 and 52, forming drain ports 308 and 309 for discharging the permeated cooling water. moreover,
Each of the side walls 304, 30r and the side wall of the housing 301 has an inlet 30 having an inner diameter of "wire diameter + a number of degrees" and communicating with each side wall and serving as a through-entrance for the electric wire 20 to be cooled.
3 is formed. Moreover, the other side of the housing 301 (
The side wall 310 (on the right side in the figure) forms an outlet 311 that serves as a through-outlet for the cooled electric wire and has an inner diameter equal to the wire diameter plus a few degrees, and is further formed to be gradually inclined toward the outlet 311VC.

Further, the felts 51 and 52 have a shape substantially similar to the cross-sectional shape of the housing 301, and are made of a multi-fibrous material.

These felts 51 and 52 (FC is the insertion groove 30
A hole whose inner diameter is approximately equal to the wire diameter of the electric wire 20 is provided at a position corresponding to the entrance 303VC when inserted into the wires 5 and 306. In this way, the cooling water tank 300 as a feature of the present invention is formed. In the above configuration,
Let's explain its operation below.

Electric wire 2 with foamable plastic insulation coating layer 22 formed thereon
0 starts foaming when it leaves the extruder 1, and first, it starts foaming in the cooling water tank 3.
Cooled by 00.

Therefore, the coating layer 22 begins to cool and harden. In general, the coating layer 22 defines the dielectric constant and therefore the capacitance of the wire 20 depending on its material and foaming rate. Therefore, in a preferred embodiment of the present invention, the cooling water tank 300 is a moving water tank, and the cooling hardening start position is changed, and the foaming rate of the coating layer 22 is controlled accordingly. For example, cooling water tank 300
When the extruder is close to 1/t-, the foamable coating layer 22 is rapidly cooled and hardened, and therefore the foaming rate is small.

Therefore, the dielectric constant of the coating layers 22, . . . increases, and the capacitance of the electric wire 20 increases. On the contrary, the cooling water tank 300
If it leaves the extruder 1, the cooling start point of the foamable coating layer 22 will be delayed, so the foaming rate will be large, and the dielectric constant of this coating layer 22 will be small, and the electric wire 201
The capacitance of becomes smaller. Therefore, when a deviation occurs between the capacitance detected by the capacitance measuring device r and the preset capacitance value, the setting control circuit 8 sends the sign (direction) of the deviation and its value. Derive a control signal according to the magnitude. Therefore, the movement and drive system 4 including the servo motor is
The movement of the cooling water tank 300 is controlled in a direction that eliminates the deviation. Therefore, the capacitance can be controlled regardless of the screw rotation speed of the extruder 1 or the wire take-up speed. Therefore, the long-period wave of capacitance change in FIG. 1 can be easily eliminated by using a moving water tank. On the other hand, in the cooling water tank 300 that is a feature of the present invention, the cooling water supply port 3
02, the cooling water 6 is injected under pressure as shown by the arrow. Accordingly, the supplied cooling water 6 fills the housing 301 and eventually flows through the inlet 303 and the outlet 3.
11, and is thrown out by the supply pressure. Therefore, no air enters the cooling water tank 300 with the moving electric wire 20, and accordingly, irregularly shaped bubbles are not generated at the cooling start position, and the velocity gradient (due to water viscosity) that occurs on the artificial side is also prevented. It disappears. Therefore, there are no small fluctuations in the cooling start position, and the instantaneous turbulent waves in FIG. 1 are eliminated. However, the torrent of cooling water toward the inlet 303 side is undesirable because it further causes fluctuations in the cooling point or scatters toward the die side.

Therefore, it is desirable to block this torrent of cooling water toward the population side at a certain position to weaken its force and allow it to overflow. To that end, in a preferred embodiment of the invention,
Felts 51 and 52 are inserted into the entrance 303 side. Therefore, the cooling water flowing toward the inlet 303 side is directed toward the insertion groove 3.
Felts 51 and 52 inserted in 05 and 306
collide with Therefore, the torrent is weakened, penetrates through the felts 51 and 52, and reaches the drain port 308 at the bottom.
and 309 and hangs down along the side wall 301.

The cooling water flowing down along this side wall 307 has a weak flow force and does not scatter toward the dice side. Therefore, the electric wire 20 to be cooled always starts cooling at a fixed position defined by the felts (51 and ) 52. Note that since the felts 51 and 52 are multi-fibrous, they have good water permeability and are soft, so even if the electric wire 20 comes into contact with them, the coating layer 22 of the electric wire 20 will not be damaged. In this way, the electric wire 20 is connected to the cooling water tank 300VC.
Since cooling starts at a fixed position in the cooling point, the instantaneous turbulent waves caused by fluctuations in the cooling point are further removed, resulting in a foamed plastic wire with stable capacitance throughout the wire. FIG. 3 is an illustrative view showing the main parts of another preferred embodiment of the present invention.

This embodiment differs from the embodiment shown in FIG. 2 in the cooling water tank 300, but is otherwise constructed in the same manner. That is, cooling water tank 3
No. 00... One side wall of the housing 301 is formed to be slightly longer than the height of the housing 301, and a side wall 304 having a similar height is formed on the outside thereof, and a side wall 307 is further formed. A felt 51 is inserted between the side walls 304 and 307, and the side walls 304 and...Using 3
01 from above as shown by the arrow, and is discharged from the drain port 308. Therefore, the force of the cooling water flowing from inside the housing 301 is weakened by the flowing water, and furthermore, the cooling water flowing from inside the housing 301 is weakened.
Penetrate into 2. Therefore, it is discharged from the drain port 309, and also flows down from the inlet 303 along the side wall 307.
In this way, the pressurized cooling water 6 is prevented from flowing to the inlet side. Similarly, on the outlet 311 side of the housing 301, a side wall 313 is disposed outside the side wall of the housing 301.

An outlet 303 is formed in the side wall 313 and the side wall of the housing 301 so as to communicate with each other. Furthermore, the space between each side wall is used as a felt insertion groove 314, and a drainage hole 31 is provided at the bottom of the felt insertion groove 314.
5 is formed. A felt 53 similar to the felt 52 is inserted into the felt insertion groove 314 (IC.). Therefore, the pressurized cooling water 6 does not flow to the outlet 311 side, so the felt insertion groove 314 (IC. As described above, according to the present invention, the velocity gradient of the cooling water or air suction on the inlet side is prevented, and there is no fluctuation in the cooling start position (cooling point) caused by this. Therefore, a foamed plastic insulated wire having a uniform capacitance over the entire wire can be obtained.

Further, according to the present invention, since the through-inlet of the cooling water tank is provided with a means for preventing the cooling water from spouting out due to the pressure of the cooling water at a certain position, fluctuations in the cooling point due to the jetting out of the cooling water are prevented. Therefore, it is possible to prevent variations in the capacitance of the electric wires.

[Brief explanation of the drawing]

Figure 1 shows →u of the C-chart model of the electric wire. FIG. 2 is an illustrative diagram showing the configuration of a preferred embodiment of the present invention. FIG. 3 is an illustrative view showing the main parts of another preferred embodiment of the present invention. In the figure, 1 is an extruder, 20 is an electric wire, 21 is a center conductor, 22 is a foamed plastic insulation coating layer, 300 is a cooling water tank, 303 is an inlet, 311 is an outlet, 4 is a moving drive system, 51, 52, 53 are 6 is a cooling water, 7 is a capacitance measuring device, and 8 is a setting control circuit.

Claims (1)

[Claims] 1. An extruder for forming a foamed plastic insulation coating layer on a conductor, and a cooling water tank for penetrating an electric wire from the extruder and cooling the electric wire, at the through-hole entrance of the electric wire of the cooling water tank. A pressure is applied so that the cooling water in the water tank is directed outward, and further, means for preventing the cooling water from running out due to the pressure at the through inlet of the cooling water tank at a certain position. A manufacturing device for a foamed plastic insulated electric wire, characterized by comprising: