Apparatus For Marking Insulated Electrical Conductors

Abstract

The deflection of color band marking material applied to cable is controlled by applying an electrical charge to the material. A direct voltage is applied between a nozzle and an annular electrode within the color material supply line to prevent variations of the sinusoidal deflection of different materials and of the same material at different times.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to the marking of insulated electrical conductors and more particularly to an improvement for the band marking of plastic insulated conductor wires.

2. Description of the Prior Art

In an earlier Patent application Ser. No. 28,903, filed Apr. 15, 1970 and assigned to the same assignee as the present case, it has been proposed to mark longitudinally advancing conductors having thermoplastic insulation with a stream of of colored material which emerges under pressure from a fixed nozzle arranged transversely with respect to the insulated conductor. Adjacent the nozzle is an electrodynamic deflection system which approximately sinusoidally deflects the color material emerging straight from the nozzle in the direction of the insulated conductor. The deflection of the stream is then amplified by passage through an approximately cylindrical, internally profiled, electrostatic amplifying electrode.

So far, this method has fully come up to what was expected of it in practice. However, since a number of different color materials are used for the marking of communication conductor wires, an unexpected phenomenon has been observed in the application of these different materials. It has been found that the various color materials exhibit greatly varying deviability. In addition the same color material showed good deflection characteristics shortly after delivery but lost this property to a large extent or almost completely after having been in store for some time. The exact physical explanation of this process has not been found as yet. It is assumed, however, that, as a result of manufacturing processes, the color material has a larger or smaller electric charge which may result from the fact that the material is charged by electrostatic induction due to the contact potential at interfaces of the metal - color material.

SUMMARY OF THE INVENTION

It is therefore the primary object of this invention to provide an improved apparatus for color marking of conductor wires so that the deflection applied to each color material is maintained at a desired amplitude.

According to the present invention, this is accomplished by applying an electric charge to the color material before it leaves the nozzle. In one embodiment, a d.c. voltage is applied between the color material in the supply line and the end wall of the nozzle before the color material is emitted. An annular electrode insulated from the nozzle is inserted in the color supply line to the nozzle, with the annular electrode and nozzle connected respectively to opposite poles of a d.c. voltage source.

Further improvement can be obtained if the annular electrode is provided with a pin-shaped extension coaxially projecting into the nozzle a short distance before the nozzle orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying FIGS. 1 and 2 show cross-sectional side views of each embodiment of the invention, and

FIG. 3 shows a schematic view of a cross-section of the system employing the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a nozzle plate 1 has an orifice 2 to which the color material is supplied through a color supply line 3 in the form of a plastic hose. The color supply line is interrupted by an annular electrode 4 of conductive material which is inserted between adjacent line portions. The end of the nozzle also has a tubular portion extending within the end of the supply line. Annular electrode 4 and nozzle plate 1 are connected respectively to opposite poles of a d.c. voltage source 5.

The apparatus shown in FIG. 2 differs from that shown in FIG. 1 in that the annular electrode 4 is formed of a cylindrical pipe length with an additional pin 6 arranged coaxially within the pipe length and extending into the adjacent tubular end part of the nozzle. The pin projects from an internal surface of electrode 4.

When a d.c. voltage is applied between the annular electrode and the nozzle plate, a different electric field is created in the space filled with the color material, which insures that the charges at the metal-color material interfaces are transferred into the color material. Thus, any charge saturation at the interfaces is prevented, and the charge is evenly distributed throughout the color material in the cross-section.

Suitable d.c. voltages in the order of 50 to 10,000 volts may be utilized to achieve the desired effect. Practical tests of the invention in the system of FIG. 3 have shown that color materials having only limited deflection by deflection electrodes 7 and amplifier 8 without the application of a charge could be charged to a sufficient extent so as to be usable for the marking of insulated conductor wires 9. Increases in the amplitude by at least 100 per cent were realized in the subsequent deflection of the stream 10.

Claims

What is claimed is:

1. Apparatus for marking a longitudinally advancing electrical conductor comprising:

a tube supplying a stream of colored marking material;

a nozzle positioned transversely at the end of said tube and directing said stream of material toward said conductor;

means for electrically deflecting said stream sinusoidally across said conductor;

means for electrically amplifying the sinusoidal deflection and applying said stream onto said conductor;

an annular electrode positioned within said tube and spaced from said nozzle to apply an electric charge to the material within said tube end to control said deflection of said material, and a source of direct voltage connected between said nozzle and annular electrode.

2. The apparatus of claim 1 wherein said nozzle and electrode are metallic and said tube is of insulating material.

3. The apparatus of claim 1 wherein said nozzle includes an orifice and said annular electrode includes a coaxial pin-shaped projection extending from an internal wall of said electrode toward said orifice.

4. The apparatus of claim 1 wherein said conductor includes an outer layer of insulation and said electrode is insulated from said nozzle.

5. The apparatus of claim 3 wherein said nozzle has an end extending into said tube and said pin-shaped projection extends within said nozzle end.

6. The apparatus of claim 1 wherein said nozzle has an end extending into said tube and said annular electrode is spaced and insulated from said nozzle end.