Crosshead

Details Crosshead Crosshead

2000-09-08

2003-10-21

Mackey, James P. (Department: 1734)

Plastic article or earthenware shaping or treating: apparatus

Distinct means to feed, support or manipulate preform stock...

Extrusion shaping means

C425S131100, C425S132000, C425S133100, C425S19200R, C425S215000, C425S382400, C425S462000

Reexamination Certificate

active

06634878

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to a crosshead for producing a stripe electric wire in which, when a conductor is covered with a synthetic resin of the ground color in a wire cover extrusion line, colored resins of a color different from the ground color are supplied in a stripe manner from stripe sub extruders, and more particularly to a crosshead in which a mixed color area (color change loss) that is produced when the color of a colored resin covering in a stripe manner, or that of a skin layer colored resin is changed can be reduced.
2. Related Art
Usually, an electric wire has a structure in which the outside of a conductor is covered with an insulator of a synthetic resin. In order to prevent erroneous connection from occurring, such an electric wire is configured as a stripe electric wire in which the insulator is covered in a strip-like manner with a resin of a color different from the ground color so as to identify the wire. In such a stripe electric wire, the stripe coloring on the insulator is performed by using a stripe sub extruder
13
, a covering resin supplied from a ground color main extruder
9
is used as a ground color resin, and the covering resin is covered with a colored covering resin in a stripe manner.
Conventionally, the stripe electric wire is produced by using a crosshead such as shown in FIG.
7
.
The crosshead body
2
of the crosshead
1
is formed into a cylindrical shape. A cylindrical nipple
4
in which the tip end is tapered and a strand conductor
3
runs through the center is fitted into the crosshead body
2
so as to maintain a predetermined gap between the nipple and the inner face of the crosshead body
2
. An insert mold
5
which is formed into a cylindrical shape is fittingly attached to the tip end portion of the crosshead body
2
. A hole through which a covered wire
6
in which the strand conductor
3
is covered with a resin is to run is formed in the center of the insert mold
5
. A die
7
which is tapered toward the center is fixedly attached to the mold. The die
7
and the nipple
4
are placed at the same center.
A ground color resin supply path
8
is opened in the crosshead body
2
. A ground color main extruder
9
is attached to the body so as to communicate with the ground color resin supply path
8
. A ground color resin is supplied from the ground color main extruder
9
into the crosshead body
2
via the ground color resin supply path
8
. The reference numeral
10
denotes a seal for attaching the ground color main extruder
9
to the crosshead body
2
, and
11
denotes a switch cock for, when the color of the ground color resin from the ground color main extruder
9
is to be changed, stopping the supply of the resin therefrom.
A stripe resin supply path
12
is opened in the crosshead body
2
. A stripe sub extruder
13
is attached to the body so as to communicate with the stripe resin supply path
12
. A colored resin for a stripe is supplied from the stripe sub extruder
13
into the crosshead body
2
via the stripe resin supply path
12
.
The reference numeral
14
denotes a seal for attaching the stripe sub extruder
13
to the crosshead body
2
, and
15
denotes a switch cock for, when the color of the colored resin from the stripe sub extruder
13
is to be changed, stopping the supply of the resin therefrom.
The switch cock
15
is used for stopping the supply of the stripe covering resin to the crosshead body
2
, and discharging a part of the stripe covering resin of a new color which is continuous to that of the old color that has been used before the color change. In the switch cock
15
, in order to smoothly supply the colored resin to the crosshead body
2
, a heater is internally disposed to heat the colored resin to an appropriate temperature.
The switching by means of the switch cock
15
is performed in the following manner. The supply route from the stripe sub extruder
13
to the crosshead body
2
is changed to a discharge route from the stripe sub extruder
13
to the outside by an adequate method. In the case where the switching of the switch cock
15
is to be conducted, before the switching of the switch cock
15
, the production line is stopped, and a hopper storing a coloring material is switched to another one so that the colored stripe covering resin to be supplied to the stripe sub extruder
13
is replaced with a resin of another color. Thereafter, the switch cock
15
is switched over from the supply route from the stripe sub extruder
13
to the crosshead body
2
, to the discharge route from the stripe sub extruder
13
to the outside. As a result of the switching of the switch cock
15
, the stripe colored resin which has been extruded by the stripe sub extruder
13
is discharged through a discharge port of the switch cock
15
.
A stripe electric wire is produced by using the thus configured crosshead
1
in the following manner. The ground color resin supplied from the ground color main extruder
9
is sent via the ground color resin supply path
8
to the tip end of the nipple
4
with passing through the gap between the inner peripheral face of the crosshead body
2
and the outer peripheral face of the nipple
4
. The surface of the strand conductor
3
is covered with the resin at a predetermined thickness by means of the tapered tip end portion of the crosshead body
2
and the tapered portion of the die
7
. When the surface of the strand conductor
3
is to be covered with the resin at the predetermined thickness, the stripe colored resin is extruded from the stripe sub extruder
13
with passing through the stripe resin supply path
12
, into the ground color resin passing through the gap between the inner peripheral face of the crosshead body
2
and the outer peripheral face of the nipple
4
, so as to be longitudinally added in a stripe manner. The colored resin is then sent together with the ground color resin, and the surface of the strand conductor
3
is covered with the colored resin in a stripe manner by means of the tapered tip end portion of the crosshead body
2
and the tapered portion of the die
7
.
In the production of a stripe electric wire by using the crosshead
1
, the color of the stripe is sometimes changed although the ground color resin is not changed. In this case, the ground color resin is continued to be supplied from the ground color main extruder
9
. In the stripe sub extruder
13
, by contrast, the running of the strand conductor
3
is temporarily stopped, the supply of the colored resin from the stripe sub extruder
13
to the crosshead body
2
is temporarily stopped, and the color of the colored resin in the stripe sub extruder
13
is changed. When the color change of the colored resin in the stripe sub extruder
13
is performed, the covering resin of the old color which is used before the color change is discharged through the discharge port (not shown) of the switch cock
15
. When the discharge of the covering resin of the new color is checked and it is judged that the output of the covering resin of the new color is completely attained, the switch cock
15
is returned to the resin supplying position to restart the extrusion covering on the strand conductor
3
. When the new colored resin is supplied from the thus configured stripe sub extruder
13
, the colored resin of the old color remains in the stripe resin supply path
12
or the like, and hence the colored resin of the old color is initially supplied, and the colored resin for forming a stripe which is supplied as a result of the color changing is then extruded in succession and continuously with the colored resin of the old color. The colored resin of the old color is mixed with that of the new color, and then replaced with that of the new color.
The resin which is initially discharged from the discharge port of the switch cock
15
is the colored resin of the old color which is used before the color change, and after a short time a resin in which the stripe covering resin of the old color is mixed with that of the new

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