Method and device for cooling coated wire

Disclosed is a method for cooling a coated wire including: preparing a water storage tank disposed between an extruder for coating a core wire with an insulating material and for feeding the coated wire forwardly, and a winder for winding the coated wire; and passing the coated wire before being wound through still water in the water storage tank thereby rapidly cooling the coated wire, the improvement comprising: preparing trough members disposed between the water storage tank and the extruder along the advance direction of the coated wire in such a manner as to cover the coated wire from the underside; and cooling the coated wire by water which is discharged to the trough members and is made to flow therein and thereafter passing the coated wire through the water storage tank. Using the above method, even in manufacture of an insulated wire having a coated outside diameter of 1 mm or less, it is possible to suppress the surface roughness of the coated wire in the degree of at least 1 .mu.m.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method and device for cooling an 
insulated wire, that is, a coated wire in manufacture thereof. 
2. Description of the Related Art 
FIG. 17 shows a conventional insulated wired manufacturing equipment for 
coating a conductive core wire with an insulating material such as 
synthetic resin or the like. As shown, the insulated wire manufacturing 
equipment includes a core wire feeding device 31, a drawing device 32, a 
core wire softening device 33, a core wire pre-heating device 34, an 
extruder 35 having a cross head for coating a core wire with an insulating 
material at the extreme end, a cooling device 36 for cooling a coated 
wire, a dancer roller device 37, and a winder 38, wherein the above 
devices are disposed in a line in that order. 
In this insulated wire manufacturing equipment, the cooling device 36 
includes a water storage tank 39 movable in the wire advance direction, 
main water tank 41 containing a plurality of shower nozzles 40, and a 
cooling capstan 42 for air cooling. In this cooling device 36, a coated 
wire 43 fed from a conventional extruder 35 is made to pass through still 
water in the water storage tank 39 while being dipped therein, to be thus 
rapidly cooled. After that, it is further cooled by water sprayed through 
shower nozzles 40 and is then air-cooled at the cooling capstan 42. 
Accordingly, the coated wire is first cooled in the water storage tank 
having the largest cooling effect, after which it is further cooled in the 
order of weakening effect on cooling. 
The reason why the water storage tank 39 having the largest cooling effect 
is first disposed among the above cooling means is as follows: namely, it 
has been considered that an insulating material formed on the surface of 
the coated wire 43 fed from the extruder 35 must be early solidified for 
preventing the insulating material from being peeled in a process of being 
wound around the winding means such as the cooling capstan 42 and the 
dancer roller device 37. 
However, as the demands for finer insulated wires and the high production 
rate thereof has been enhanced, the conventional manufacturing equipment 
has encountered in the following problem: for example, in manufacturing 
fine wires having a coated outside diameter of 1 mm or less, the surface 
roughness often exceeds 10 .mu.m, and consequently, in a process of 
twisting the number of coated wires, they are rubbed with each other 
thereby causing cutting-off of the coated surfaces, further in the very 
worst case, they are reduced in the coated amounts in the degree of 
exerting adverse effect on the insulating property. 
The present inventor has examined and found the fact that such 
deterioration of the surface roughness is due to the above-mentioned 
cooling device 36, especially, the water storage tank 39 constituting the 
rapid cooling stage. Namely, the rapid cooling of the coated wire 43 in 
the water storage tank 39 is required for solidifying the surface: 
however, the rapid cooling causes huge thermal shock. In a fine coated 
wire, such thermal shock causes a thermal stress difference between the 
core and the coating material, which makes the surface roughness larger in 
the non-negligible degree. 
SUMMARY OF THE INVENTION 
Taking the above into consideration, the object of the present invention is 
to provide a method and device for cooling a coated wire capable of 
suppressing the surface roughness at a low degree even in manufacturing 
the fine wire having a coated outside diameter of 1 mm or less. 
To achieve the above object, in a first aspect of the present invention, 
there is provided a method for cooling a coated wire including: preparing 
a water storage tank disposed between an extruder for coating a core wire 
with an insulating material and for feeding the coated wire forwardly and 
a winder for winding the coated wire; and passing the coated wire before 
being wound through still water in the water storage tank thereby rapidly 
cooling the coated wire, the improvement comprising: preparing trough 
members disposed between the water storage tank and the extruder along the 
advance direction of the coated wire in such a manner as to cover the 
coated wire from the underside; and cooling the coated wire by water which 
is discharged to the trough members and is made to flow therein and then 
passing the coated wire through the water storage tank. 
Furthermore, in a second aspect of the present invention, there is provided 
a cooling device for cooling a coated wire including a water storage tank 
disposed between an extruder for coating a core wire with an insulating 
material and for feeding the coated wire forwardly and a winder for 
winding the wire coated, whereby passing the coated wire before being 
wound through still water in the water storage tank for rapidly cooling 
the coated wire, the improvement comprising: a cooling means provided 
between the water storage tank and the extruder, which includes trough 
members disposed along the advance direction of the coated wire passing 
between the water storage tank and the extruder in such a manner as to 
cover the coated wire from the underside for cooling the coated wire by 
water which is discharged to the trough members and is made to flow 
therein. 
Prior to the detailed description of the preferred embodiments, there will 
be explained the function of the present invention. 
In the trough member, the cooling of the coated wire is performed by water 
flowing within the trough member. Namely, in the trough member, cooling 
water does not usually cover the coated wire differently from the cooling 
by the water storage tank. Accordingly, the cooling effect of the trough 
member is lower than the water storage tank, and is higher than the 
water-spraying at the shower nozzles. 
The present invention has a feature of cooling the coated wire at the 
trough member having such an intermediate cooling effect disposed at the 
head of the cooling means, and then rapidly cooling it at the water 
storage tank. Namely, the coated wire first cooled by the trough member is 
inferior in the surface solidified state to that in the conventional 
manner; but is surface-solidified sufficiently to suppress the thermal 
stress difference which causes deterioration of surface roughness. Thus, 
in the next stage, the coated wire is earnestly solidified by rapid 
cooling at the water storage tank; however, since being almost formed in 
its surface shape by cooling at the trough member, it is less liable to be 
affected in surface roughness by rapid cooling.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Hereinafter, one embodiment of the present invention will be described in 
detail with reference to the accompanying drawings: 
Referring to FIGS. 1 and 2, reference numeral 1 shows a cooling device for 
cooling a coated wire according to the embodiment. The cooling device 1 
includes a first cooling means 3 containing V-shaped troughs 2, second 
cooling means 5 composed of a water storage tank 4, and a third cooling 
means 7 having a plurality of nozzles 6 therein, wherein the cooling means 
3, 5 and 7 are linearly disposed in the advance direction of the coated 
wire 8 (from left to right in FIG. 1) in that order. In addition, an 
extruder (not shown) for coating a core wire with an insulating material 
is disposed in back of the first cooling means 3 (on the left in FIG. 1), 
and a winder (not shown) is disposed in front of the third cooling means 7 
(on the right in FIG. 1) through a cooling capstan or the like, wherein 
the dispositions and constructions thereof are the same as in the 
conventional equipment (see FIG. 17). 
The first cooling means 3 includes a receiving member 11 formed in a 
U-shape in section which is mounted on a mounting base 10 in such a manner 
as to be movable in the advance direction of the coated wire 8, and two 
V-troughs 2 and 2 contained in the receiving member 11 on the front and 
rear sides respectively so as to be opened upwardly. Water discharge pipes 
12 and 12 are respectively provided on the upper rear sides of the 
V-troughs 2 and 2. 
As shown in FIGS. 3 and 4, each of the V-troughs 2 and 2 is disposed along 
the advance direction of the coated wire 8 to cover the coated wire 8 from 
the underside and to position the coated wire 8 in the vicinity of the 
lower corner portion 13 thereof. Accordingly, the coated wire 8 fed from 
the extruder first advances along the vicinity of the lower corner portion 
13 in the V-trough 2, to be thereby cooled by water which is discharged 
from the water discharge pipe 12 and is made to flow ahead at the lower 
portion in the V-trough 2. Incidentally, reference numeral 14 indicates an 
air cooling zone disposed between the V-troughs 2 and 2. 
The second cooling means 5 is composed of a water storage tank 4 including 
two columns 15 and 16, and a water tank 17 formed into a U-shape in 
section installed between the columns 15 and 16. The water tank 17 
contains in an internal space section thereof two partition walls 19 and 
19, each having a hole 18 through which the coated wire 18 passes. The 
partition walls 19 and 19 are movable in the longitudinal direction to 
adjust the longitudinal length of the water storage tank 4, thereby making 
it possible to change the length of the rapid cooling zone for the coated 
wire 8. Also, the receiving member 11 is freely moved in the longitudinal 
direction and is fitted on the rear end side of the water tank 17, and 
further, the fitting lapping length is designed to be changed thereby 
making it possible to change the length of an air cooling zone 20 between 
the first and second cooling means 3 and 5. 
Reference numeral 21 indicates a calorifier for keeping the water 
temperature in the water storage tank 4 constant and is connected between 
the front and rear columns 15 and 16 through a cold water piping 22 and 
hot water piping 23. Namely, cold water fed from a supply port 24 of the 
cold water piping 22 is supplied to the three ways to the columns 15 and 
16, and the hot water tank 21 at respective constant amounts through a 
three-way valve 25. The hot water from the hot water tank 21 is supplied 
to the rear column 16 at a constant amount through a three-way valve 26 in 
the hot water piping 23. Thus, by the balance of the supplied amounts of 
cold water and hot water, the water temperature in the water storage tank 
4 is kept constant. Incidentally, the piping passing through the columns 
15 and 16 is naturally inserted into the water storage tank 4. 
The third cooling means 7 includes a water tank 27 formed into a U-shape in 
section disposed in front of the front column 15, and a plurality of 
shower nozzles 6 provided on the side wall of the water tank 27 so as to 
be crosswise opposed to each other. Accordingly, the coated wire 8 rapidly 
cooled by the second cooling means 5 advances to this third cooling means 
7 through the air cooling zone 28 directly after the rear partition wall 
19, and is cooled by water sprayed from the right and left shower nozzles 
6 as shown in FIGS. 7 and 8. In addition, reference numeral 29 indicates a 
control panel for controlling moving amount of the receiving member 11 and 
temperature change by the hot water tank 21. 
With this construction, since the coated wire 8 is cooled at the V-troughs 
2 and 2 inferior in the cooling effect to the water storage 4 prior to the 
water storage tank 4, and is then rapidly cooled in the water storage tank 
4, it is possible to suppress the surface roughness of the fine wire 
having a diameter of 1 mm or less in the degree lower than in the 
conventional manner. 
Namely, the cooling function of the V-trough 2 lies in that the coated wire 
8 is cooled with water flowing therein, and consequently, is quite 
different from that of the water storage tank 4 in which the coated wire 8 
is cooled with cooling water always covering the circumference thereof. 
Furthermore, in the V-trough 2, the flowing water can sufficiently wet the 
circumference of the coated wire 8 compared with the water-spraying from 
the shower nozzles 6. Consequently, the cooling of the V-trough 2 has an 
intermediate cooling effect between those of the water storage tank 4 and 
the shower nozzles 6. Therefore, since the V-trough 2 somewhat solidifies 
the surface of the coated wire 8 before rapid cooling by the water storage 
tank 4, it is possible to significantly reduce deterioration of the 
surface roughness caused by the thermal stress difference in comparison 
with the conventional manner. 
Furthermore, in this embodiment, since the air cooling zones 14 and 20 are 
respectively provided between the V-troughs 2 and 2, and between the first 
cooling means 3 (V-trough 3) and the water storage tank 4, the surface 
solidification by cooling and the heat transmission of inner heat in the 
air cooling zones 14 and 20 to the surface side are repeated. This 
equalizes the thermal stress thus more effectively preventing 
deterioration of the surface roughness. 
The present invention is more particularly described by way of examples. 
In the examples, comparison between various cooling methods were made using 
the following coated wire 8: 
Coated outside diameter: .PHI. 0.86 mm (core wire diameter: .PHI. 0.40) 
Coating material: HDPE (high density polyethylene) 
(1) EXAMPLE 1 (SEE FIG. 9) 
Cooling method: V-trough+V-trough+water storage tank+shower 
Lengths L.sub.1, L.sub.3 of respective V-troughs 2, 2: 50 cm 
Length L.sub.2 of air cooling zone between V-troughs 2, 2: 100 cm 
Length L.sub.4 of air cooling zone between V-trough 2 and water storage 
tank 4: 100 cm 
Length L.sub.5 of water storage tank 4: 100 cm 
Under the above cooling condition, the coated wire 8 was manufactured. As a 
result, the surface roughness of the coated wire 8 is approximately within 
the range from 5 to 6 .mu.m as shown in FIG. 10. Incidentally, in this 
figure, the abscissa indicates the length of the coated wire 8, and the 
unit length is 10 mm (which are common in FIGS. 12, 14 and 16). 
(2) EXAMPLE 2 (SEE FIG. 11) 
Cooling method: V-trough+water storage tank+shower 
Length L.sub.3 of V-trough 2: 50 cm 
Length L.sub.4 of air cooling zone: 100 cm 
Length L.sub.5 of water storage tank 4: 100 cm 
Under the above cooling condition, the coated wire 8 was manufactured. As a 
result, the surface roughness of the coated wire 8 is approximately within 
the range from 8 to 9 .mu.m as shown in FIG. 12, which is less than the 
target value of 10 .mu.m. 
(3) EXAMPLE 3 (SEE FIG. 13) 
Cooling method: Water storage tank+shower 
Length L.sub.5 of water storage tank 4: 100 cm 
Under the above cooling condition, the coated wire 8 was manufactured. As a 
result, the surface roughness of the coated wire 8 is approximately within 
the range from 14 to 15 .mu.m as shown in FIG. 14, which exceeds the 
target value of 10 .mu.m. 
(4) EXAMPLE 4 (SEE FIG. 15) 
Cooling method: V-trough+shower 
Length L.sub.1 of V-trough 2: 50 cm 
Under the above cooling condition, the coated wire 8 was manufactured. As a 
result, the surface roughness of the coated wire 8 is approximately within 
the range from 12 to 13 .mu.m as shown in FIG. 16, which exceeds the 
target value of 10 .mu.m. 
(5) OTHERS 
Futhermore, experiments were repeated in various cooling methods other than 
the above methods, such as, water storage tank+water storage tank, air 
cooling+shower, steam cooling+water storage tank, air cooling+water 
storage tank. As a result, in either experiments, the surface roughness 
exceeds the target value of 10 .mu.m. 
From the above Examples, it is revealed that the pattern of disposing a 
number of V-troughs directly before the water storage tank 4 is most 
effective. Furthermore, from the difference between Example 1 and 2, it is 
also revealed that surface roughness is effectively reduced by repetition 
of the cooling by V-troughs and air cooling thereby achieving somewhat 
equalization of thermal stress and surface solidification, before rapid 
cooling by the water storage tank 4. 
In addition, the present invention is not limited to the above embodiment. 
The trough may be formed into such a shape as generating a constant water 
flow in a space section, for example, a U-shape or semi-circular or the 
like.