DE885576C - Method of manufacturing electrical cables - Google Patents

Description

(WiGBl. P. 175)

ISSUED AUGUST 6, 1953

T 47

The invention relates to electrical cables and, more particularly, to cable jackets.

To prevent water from entering the soul or the souls of electrical cables, especially when insulating with paper or other hygroscopic material, it is common to use a to use pressed lead sheath around the cable.

A lead jacket, however, has the disadvantage of being brittle due to vibrations or due to corrosion to become porous. These drawbacks become even more apparent when you look at the weight to reduce or to save lead, the wall thickness of the lead jacket is reduced below the usual level.

In order to avoid these disadvantages, it has been proposed that the lead sheath, in particular one thin-walled lead jacket to be provided with a waterproof coating made of thermoplastic material, which is applied, for example, in the extruder.

There are also cables where the metal jacket consists of a metal band or bands that are wound lengthwise or helically over the cable cores. In some cases it will be here too a pressed-on thermoplastic coating is provided to create a waterproof construction.

According to the invention, in an electrical cable with a metallic sheath and an outer waterproof coating made of a thermoplastic substance, the outer covering thereby on the Metal jacket applied that you apply the wrapping material in a finely divided state and uses the heat present in the cable or its jacket to remove the jacket material to soften or to cling to

when it is in with the outer surface Touch comes. After removing the excess material, a smooth one then forms Coating.

S The temperature to which the cable jacket to be coated is heated can be such be that only those with the mantle surface in the immediate Particles of the powder standing in contact are softened or melted ίο be. Larger coating thicknesses can, however can be achieved by using higher temperatures, or you can also use the coating create that one repeatedly heated in several stages and applied the powder. In order to ensure a smooth and gapless coating made of thermoplastic material, gradually apply moderate heat, for example by passing the cable through a Zone that is heated with infrared rays or in any other suitable manner.

The thermoplastic material can be sprayed on

or be dusted on; however, it is more practical to pass the cable through a quantity of powder! on en in a suitable container.

The finely divided used according to the invention The material is preferably polyethylene, pure or in a mixture with other substances; meanwhile should the Of course, the invention is not restricted to this but other thermoplastic compositions can also be used in a similar manner will. Synthetic rubber and shellac may be cited as examples.

To explain the invention, a schematic layout plan is to be evaluated as an example Enclosed annex in which a lead sheathed cable is covered with polyethylene can be.

In the drawing, C denotes a lead-sheathed cable, on which a waterproof coating is to be applied, from the exit from the mouthpiece D of a lead press P to winding onto a receiving drum T. When the cable leaves the press mouthpiece D , it runs right through one rotating box B containing polyethylene powder. Here the still hot cable is given a coating of polyethylene, and the heat present in the cable is sufficient to make the polyethylene plastic so that it adheres to the surface of the cable jacket. The box B ' is rotatably mounted in order to stir up the powder and thereby achieve that the entire surface of the lead jacket is coated. This rotation of the box B can be brought about by a belt drive which is expediently derived from the drive of the take-up drum T.

Of course, instead of rotating the box B, it is also possible to use other types of drive in order to ensure a satisfactory covering of the cable. '

After applying the polyethylene or other coating material, one submits to that Cable expedient for heating; this removes the excess powder and at the same time the coating made uniform and completely sealed.

In the embodiment shown, after leaving the box B , the cable passes a wiping device W, which can consist of brushes, and then enters a chamber A which is heated to 160 ° C., for example.

The box B is of course positioned relative to the die D so that the lead is at an adequate temperature to cause the polyethylene to adhere; to be useful, a distance of about 45 cm has been found by the press die where the temperature was measured in a particular case with about 180 'C ^01. In this way a smooth coating of the order of 0.6 mm thick can be obtained.

In the drawing, L denotes a cooling device, e.g. B. an air blow ring, which can be attached to cure the coating when it leaves the heating chamber A. The cable then finally runs onto the take-up drum T.

Another method of achieving the object of the invention that is particularly useful when the Metal jacket consists of lengthwise or helically applied bands, uses a electronic heating of the cable jacket, with induction heating a power of 2 to 3 kW are sufficient to treat a lead jacket of 25 mm, which moves at a 'speed moved forward at 90 m / h.

Claims (3)

PATENT CLAIMS: i. Process for the production of electrical cables, the metal sheath of which with a coating made of thermoplastic material, ioo characterized in that the thermoplastic Substance in a finely divided state is brought into contact with the cable, and that the necessary heat to soften or plasticize the substance through in the cable or metal sheath existing residual heat or by heating the cable the required temperature is supplied, while excess material from the so surface reference formed on the metal jacket is finally removed. 2. The method according to claim i, characterized in that the cable (C) with its pressed-on lead sheath is passed through a bath (B) made of powdered polyethylene or another finely divided substance before the sheath has cooled. 3. The method according to claim 1, in particular for use on cables with a metal jacket, which is formed from a band or bands, characterized in that the Belts are heated by induction current. For this purpose ι sheet of drawings ) 5303 7.53