US2884129A

US2884129A - Valve which permits the circulation of work material during the stoppage of a cable sheathing press

Info

Publication number: US2884129A
Application number: US434828A
Authority: US
Inventors: Ture A Ljungberg
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1953-06-09
Filing date: 1954-06-07
Publication date: 1959-04-28
Anticipated expiration: 1976-04-28

Description

A ril 28, 1959 VALVE WHICH PERMITS Tl lE CIRCULATION OF WORK MATERIAL DURING Filed June 7, 1954 T A. LJUNGBERG 2,884,129

THE STOPPAGE OF A CABLE SHEATHING PRESS 2 Sheets-Sheet 1 April 8, 1959 A. LJUNGBERG 2,884,129

VALVE WHICH PERMITS THE CIRCULATION OF WORK MATERIAL DURING THE. STOPPAGE OF ,A CABLE SHEATHING PRESS Filed June 7, 1954 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent VALVE WHICH PERMITS THE CIRCULATION OF WORK MATERIAL DURING THE STOPPAGE OF A CABLE SHEATHING PRESS Ture A. Ljungberg, Stuvsta, Sweden, assignor to Allmanna Svenska Elektriska Aktiebola'get, Vasteras, Sweden, a corporation of Sweden Application June 7, 1954, Serial No. 434,828 Claims priority, application Sweden June 9, 1953 2 Claims. (Cl. 207--4) fore enter the press at a temperature which is considerably higher than the temperature at which it is extruded. Therefore, a cooling flund has to be supplied to the press, which fluid takes up the difference between the heat content :of the molten metal supplied and that of the extruded solidified metal. A press having a high output must, therefore, be cooled considerably with respect to the temperature of the metal passing through the press, and if the metal becomes stationary for any reason or if the output decreases, the metal passing through the press becomes cooled too much. If there are no particular arrangements for immediately changing the quantity of cooling fluid supplied, the molten metal in the press can solidify .and give rise to great trouble in starting the press again. Stopping or slowing down of the extrusion process is often caused by external occurrences, for example the repair of worn insulation of the cable or exchange of the cable drum.

The present invention relates to means for enabling the extrusion speed to be altered without necessitating a change in the rate at which cooling fluid is fed to the press. This is obtained by providing the press with a controllable valve through which metal surplus to the extrusion requirement is discharged in the form of a tube or rod from a zone in the press in which the metal is in a plastic condition. The metal passing through the valve is preferably returned to a melting pot from which the molten metal flows to the press. Due to the high pressures involved the walls of the press casing have considerable thickness. This makes it impossible for the control valve to be placed outside the press, since if the control valve were placed outside the press a considerable reduction of the pressure would then occur within the relatively long and narrow duct between the interior of the press and the valve, which would give rise to greater friction resistance than the normal path of the metal through the press, and, therefore the valve would become ineffective. The valve, therefore, comprises a seat mounted in the wall of the press, said seat preferably being positioned closer to the inner surface of said wall than to the external surface thereof.

On the accompanying drawings one embodiment of a press head for covering cables with a metal mantle is shown comprising the melting pot for the metal and the supply pipe for the molten metal to the press head and the return pipe for the surplus metal from the pres head to the melting pot. Fig. 1 shows the press with the melting pot and the supply and return pipes of the press head. Fig. 2 is a section through the press head taken at right angles to the direction .of advance \of the cable through the press. Fig. 3 is a section through the press head taken along the center line of the cable along the line AA of Fig. 2. Fig. 4 shows the valve according 2,884,129 Patented Apr. 2 8, 9

to 'the invention in enlarged scale. Fig. 5 shows in a still larger scale the valve as viewed in the direction of the arrow B in Fig. 2. Fig. 6 is a perspective view of the valve. Fig. 7 is .a view of the valve from the other end of Fig. 5. The melting pot is designated by 11 and the casing or press head by 12. Designated by 13 is the incoming portion of the cable and by 14 the outgoing portion of the metal-covered cable, which is advanced through the press head in the direction of the arrow. Designated by 15 are heating elements arranged in the press head, the former also being provided within chan nels 16 around the foot of the press head. The heat is applied here, when the press is to be started. Designated by 17 (Fig. 2) are cooling water ducts located in said foot, the purpose of which shall be described later on. The molten metal is suppiied through the pipe 18 into the casing containing the supply screw 19, which is driven by a motor through a worm gear not shown on the drawings. The metal is subjected to a pressure by the screw 19, and the molten metal is transformed into plastic state by the cooling fluid supplied through the cooling duct 17. The metal is then pressed upwards into a duct 20 and around a mandrel 21 (Fig. 3) and out through an orifice 22, thereby forming the sheath .ofthe cable. The positions :of the mandrel 21 and the orifice 22 with respect to each other, and hence the thickness of the sheath, are controlled by means of threaded

sleeves

23 and 24. When the press is adjusted for normal operation, molten metal is fed around the screw 19'1at the exact rate which is required in order to sheath the cable at that speed at which the latter is being advanced through the press. If now the speed of advance of the cable is reduced or if the cable is even stopped, so that the consumption of the molten metal for sheathing the cable decreases or is interrupted while the quantity of cooling water is the same, the metal within the press will soon solidify with the result that it will be very diflicult to heat the press for starting it again. To prevent the metal from solidifying within the press head, the valve generally indicated by 25 is inserted. It consists as shown in an enlarged scale in Fig. 5 viewed in the direction of the arrow B in Fig. 2 of a conical plug or mandrel 26 having three or more wings 27, which engage the wall of a conical inner portion of a passage extending through the casing wall at a point downstreamward of the screw and in the zone of the cooling ducts where the metal has become plastic. 29 is a member having an internal conical channel slidably mounted in the passage and having a valve seat engageable with the pointed end 28' of plug 26 which extends beyond the wings 27. A hollow screw or threaded member 30 is threadedly mounted in the passage to engage member 29. Member 30 has an internal tapered channel and is provided with a toothed gear wheel 31 for being operated remotely by means not shown :on the drawings. Fig. 4 shows the Valve in closed condition. When the toothed wheel 31 is rotated in the direction for opening the valve, the pressure exerted by the screw 19 presses the valve seat member 29 in such a direction (to the left in the drawing) that a gap is produced at 28 around the mandrel 26. By suitably adjusting :said gap, a flowing off of the surplus metal is obtained at reduced speed of advance [of the cable, so that the risk for the metal to solidify in the press head at reduced speed of advance of the cable is eliminated. The surplus metal flows through the screw threaded means 30 in the form of a tube the thickness of which depends on the magnitude of the gap. The surplus metal may be led back to the melting pot 11 by a pipe 32 (Fig. 1).

In operation, the gear wheel 31 (Fig. 4) is normally in such a position that the inner end of the screw 30 holds the valve seat of member 29 in close engagement with the plug 26, so that there is no escape of surplus metal, but when the extrusion process is slowed down or stopped, and escape of surplus metal is therefore desired, the gear 31 is turned so as to move the screw 30 outwardly, so that the annular seating surface at the right hand end (Fig. 4) of the valve seat member 29 is moved raway from plug 26 by the pressure of the metal against the inner face of the valve seat, while the plug remains with its wings 27 in close engagement with the tapered wall of the inner part of the passage. The surplus metal is then free to pass through the annular gap at 28 between the

parts

26 and 29, as the part 29 is moved outwardly (to the left, Fig. 4) by the pressure of the metal, and the surplus metal issues through the part 29 and through the 'hollow screw 30, in the form of a tube having a wall thickness determined by the setting of the gear 31 and the consequent distance between the

parts

26 and 29.

I claim as my invention:

1. A fluid-cooled metal press for the continuous extrusion of a metal to form a sheathing for longitudinally moving articles, in which the press receives the metal in a molten state and extrudes the metal in a solidified state after cooling 'in the press, said press comprising a press casing, :an extrusion screw in the casing, sheathing means comprising a core and a die located in the casing in advance of the screw and through which the said moving articles are advanced, means for the supply of molten sheathing metal to the screw, cooling fiuid ducts in said casing to bring the molten metal therein to a plastic condition, an escape passage extending through the wall of said casing and located downstreamward of said screw and in the zone of said cooling ducts, within the zone of the casing in which the metal becomes plastic, said passage serving for the escape of surplus plastic metal, and a valve arranged in said passage and controlling the passage of the plastic metal through said passage so that the surplus metal can escape from the press.

2. A metal press according to claim 1 in which the said valve comprises a conical plug having an annular end surface and provided with outwardly tapered radial wings for the passage of the surplus metal therebetween, a conical bore in the said passage for receiving and retaining said wings, a movable member in said passage having a valve seat adapted to engage the said annular end surface of said plug, said member being provided with an internal conical channel for the passage of the surplus metal, a hollow :screw mounted within the said passage and engaging said member and provided with an internal tapered channel forming :a continuation of the channel in said member, and a gear wheel for actuating said screw to adjust the distance between the said annular end surface of the plug and the said member.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,859 Bary Aug. 8, 1916 2,025,666 Hanff Dec. 24, 1935 2,105,083 Kagi et al Jan. 11, 1938 2,161,570 Harris June 6, 1939 2,219,888 Duclos Oct. 29, 1940 2,385,574 Hyprath Sept. 25, 1945 2,743,812 Ljungberg May 1, 1956 FOREIGN PATENTS 271,378 Germany Mar. 11, 1914