Cable Sheathing Press

Time-tried dimensions of this type of cable sheathing press are compiled in Table 3. 

Aluminum cable sheathing presses are both of the single-ram and the twin-ram type. The twin-ram press offers the advantage that the resistance to deformation in the die-block is lower, but is not practical for presses in which both aluminum and lead sheathing is extruded. Twin-ram presses are made both in vertical and horizontal design. Choice of type depends on the space available at the site of erection. If space is... 

The idea of developing a continuously operating cable sheathing press, by means of which it is possible to eliminate solidification and waiting periods and to avoid stop marks - the so-called bamboo-rings -... 

Notwithstanding the many advantages of screw presses, they still have some important imperfections and that is why hydraulic lead cable sheathing presses continue to find a wide application. 

A continuous hydraulic aluminum cable sheathing press the design of which has only recently been published, is shown in Fig. 53. With this press which is fed wdth solid billets, it is not so important to save the charging- or waiting time as this is of minor importance as compared with the setting period of lead. It is much more important, however, to obviate the stop marks - or to take measures whieh prevent the cable insulation from charring and eliminate a variation in the wall thickness while the die-block is released. The breath-... 

A cable of the following dimensions is to be extruded from one charge of the container of a cable sheathing press 55 mm outside diameter 1.8 mm wall length I = 110 m emerging speed = 20 m/min without stop mark. 

PRESSES FOR THE MANUFACTURE OF LEAD AND ALUMINUM CABLE SHEATHING... 

The simplest means of obviating stop marks would be to employ a container holding such a quantity of lead as would be required for the manufacture of the largest and longest cable sheath. This would mean, however, the use of a very powerful and big press, the price of which would be extremely high so that for this very reason cable manufacturers rather prefer to work with a smaller press and to put up with the stop marks. 

Fig. 44. Shop photo of 2,000-ton vertical lead sheathing press as used for the vulcanization of cables. Press in four-column design with underlying hydraulic cylinder, moving container, traversable extrusion ram and swinging device for charging of billets (By Breda Fucine, Milan)...

Presses used for the production of tubes, solid rods, hollow sections, wire, and cable sheathing in nonferrous metals... 

Because the output of these bridges is in the range of millivolts, the cables utilized to carry the signal are normally shielded with a braided or foil-lined sheath around individual wires. The shield, as a rule, is connected to the amplifier, but never touches the actual instrumented equipment (i.e., tablet press). If this rule is violated, a ground loop may generate electrical noise and present a dangerous electrical shock hazard. 

Berlin. These cables consisted of a gutta-percha covered conductor threaded into a lead pipe, the diameter of which was subsequently reduced by cold drawing until the pipe fitted tightly around the cable core. Three decades had to pass until in 1882 there was used a press, constructed by Werner von Siemens, on which the lead sheath was directly extruded on to the cable core. 

Fig. 48. Vertical twin-ram aluminum cable press, as per Fig. 47, extruding cables with corrugated sheathing. Courtesy of Felten vfe Guilleaiime CarlswerkAG, Koln-Miilheim (By Hydraulik, Duisburg)...

A great drawback is that a screw press cannot be suddenly stopped without causing impairing effects, when, for instance, a faulty spot in the insulation of the incoming cable core has to be remedied. In such case temperature troubles causing damage to the sheathing, would occur im-... 

Discolouration during vulcanisation is a specific problem in coloured cable jackets or hose covers made by the lead press method. The cause is the reaction between the lead sheath and any available sulphur in the compound, forming black lead sulphide. For this reason, sulphur modified polychloroprenes should not be used or any ingredients containing or liberating sulphur during cure, such as TMTD or factice. ETU in combination with MBTS would be the preferred accelerator. 

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