US1664976A - Machine for making metallic tubing - Google Patents

Description

A ril3,1928. j 1,664,976 'F.HANFF MACHINE FUR MAKING METALLIC TUBING Filed oct. 16 1925 [Iilj i i 6 I 1 I 23 iiii 2/ I 2a" I 76 1 H ii Patented Apr. 3, 1928.

UNITED STATES PATENT OFFICE.

FERDINAND HANFF, F BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOB TO SIEMENS-SCHUCKERTWERKE GESELLSGHAF'I. MIT BESCHRKNKTEB HAI'TUNG, 01' SIEMENSSTADT, NEAR BERLIN, GERMANY, A CORPORATION OF GERMANY.

MACHINE FOR MAKING METALLIC TUBING.

Application filed October 16, 1925, Serial No. 62,829, and in Gerinany December 1, 1924.

My invention relates to a machine for making metallic tubing or for presslng a seamless metallic sheath around cables.

I In the hitherto employed tubeor sheath- 5 making machines having a single or a plurality of pressing-cylinders it is necessary to interrupt the operation for the purpose of charging the pressing-cylinders with plastic or molten metal. interruption the quality of the tube or the cable sufiers because the place where the metal came to rest, known as the bambooring, which is formed in the die when the machine is stopped has a strong tendency to break, particularly in the caseof thinwalled tubes or sheaths. The electric qualities of the cable to be sheathed are further more liable to be injured because the cable is during the time of stoppage of the machine heated by the hot metal beyond the normal temperature at theplace located in the die.

It has been attempted to eliminate the detrimental effect of the interruption of the process by continuing the pressing action slowly or intermittently immediately after introducing a new charge and before the liquid metal in the press cylinder has cooled down. This method is, however, not able to eliminate the detrimental effect of the interruption in the operation of the machine.

It has also been proposed to employ metal presses with two pressing-cylinders and two plungers which operate alternately so that a 35 charging of the press cylinders is possible without interrupting the operation of the machine. l/Vith this arrangement no satisfactory results were obtained because it was temporarily necessary to keep both pistons in action to obtain a good passage from the work of one piston to that of the other.

The object of my invention is to avoid the drawbacks attached to the hitherto known tube or sheath making methods.

With this and other ends in view my invention consists essentially in providing two or more plungers which work in one pressing-cylinder upon the plastic liquid metal contained therein, at least one of which lungers can be temporarily stopped and its cylinder closed for recharging while the other plungers continue to operate. In this case a continuous pressing takes place without the flow of the material bemg discon- Owing to this tinned or without the uniformity of the tube or the sheath being detrimentally afiected during the passage from the work of one piston to that of the other.

One embodiment of my invention is shown in longitudinal vertical section in the draw- 00 mg. I

Referring to this figure, 11 designates a die block in which the die 12 for the issuing metal is arranged. Upon this block is mounted the cylinder block 13 enclosing the chamber 14 which contains the metal. In the cylinder-block 13 are inserted the two steel bushings or liners 15 and 16 with'th'e cylinder bores 17 and 18, shown here axially at right angles to each other. The steel liners are adapted to be heated or cooled by theg'ackets 19 and 20. In the liners move the plungers 21 and 22. The cylinder bore 18 is adapted to be closed by a slide 24. The charging of the machine with fresh metal-76 takes lace through charge opening 25 with the sllde closed after withdrawal of the plunger or piston 22 sufiiciently to expose the charge opening. The finished tube or the cable sheath issues from the die 12. For actuating the-stop slide 24 a threaded spindle 23 with handwheel is provided in the embodiment illustrated. It is, however, obvious that other equivalent means may be employed to accomplish the purpose of tem- 35 I porarily shutting ofi cylinder 16 from communication with metal chamber 14.

The machine operates in the following manner: The machine is charged with a liquid metal, the temperature of which is kept :9 at the desired height by the aid of the cooling or heating jackets previously mentioned. When pressure is applied to the plunger 21 a pressure is exerted upon the charge of metal in the chamber 14 under the action of which the metal issues through the die 12 in the center of which for instance the cable to be sheathed is located, (not shown). Die structures of this kind are known in-the art and the detail illustration and description there- 1 of is therefore omitted. The plunger 21 then, under the pressure exerted, descends slowly. When the stock of metal in the cylinder 17 has been reduced to a certain extent the cylinder 18 is closed by the slide 24, the plunger 22 is withdrawn and the cylinder 18 is charged with fresh metal through the charge opening 25. When the charge has been introduced the slide is opened again and the plunger 22 pushed forward. By the flow of the metal from the cylinder 18 into the metal chamber 14 and the cylinder 17 under high pressure the piston 21 is raised into its upper position without the squirting of the metal from the die 12 being-in terrupted. When the feeding stroke of piston 22 is completed the piston 21 has again arrived in its uppermost position, so that now it can descend anew under the ressure applied to it (with piston 22 standlng still in the position shown) thereby taking over the delivery of metal to die 12. The above described cycle is repeated when the stock of metal in the cylinder 17 has dropped down to a certain level. It will be noted that the diameter of cylinder 18 is larger than the diameter of cylinder 17 so that when the former takes charge of feeding cylinder 17 suflicient metal is supplied to take care of feeding the die 12 at the same time.

The plunger 22 thus acts as supply pump in which the suction is substituted by an actual charging through opening 25 while the plunger 21 carries out the pressing-or squirting operation proper during the major portion of the time.

To give an idea of the practical range of pressure applied in devices of this character it may be assumed that on the pressurepiston is exerted a pressure of the order of 2,000,000 kilograms. When piston 22, after its cylinder is charged with fresh liquid metal, is moved in a slightly higher pressure is applied to that piston, in order to lift piston 21. However, the outside pressure of 2,000,000 kilograms remains resting upon piston 21. In other words this piston is constantly exposed to a uniform outside pressure in contradistinction to piston 22 whose outside pressure is alternately applied and relieved. Through this arrangement thus a substantially uniform pressure exists in chamber 14, the slight increase in pres-. sure applied to piston 22 being negligible compared with the order of permanent pressure applied to piston 21.

According to my invention the plunger 22 may altogether be replaced by a pump tively to each other or whether the plunger 22 stands vertical and 21 horizontal.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof I and all such modifications are intended to be covered by the appended claims.

I claim as my invention 1.. In a machine for making endless tubes or for providing cables with a I seamless metallic sheath, the combination of a pressing chamber containing the plastic-liquid metal and two cylinders and plungers there in disposed to exert pressure upon said metal one being the operating plunger and the other the feeding plunger, the operating plunger standing constantly under uniform outside pressure and means for temporarily separating the feeding plunger from the metal to permit the release of the pressure upon that plunger and the charging of its cylinder with fresh metal.

2. In a machine for making endless tubes or for providing cables. with a seamless metallic sheath, the combination of a pressing chamber containing the plastic-liquid metal and several cylinders and plungers therein adapted to act upon said metal, one being the operating plunger and the other the feeding plunger, the operating plunger standing constantly under uniform pressure, the feeding plunger being disposed to press metal into said chamber and a slide in the feeding cylinder adapted to close the discharge end of said cylinder for the purpose of recharging with fresh metal.

In testimony whereof I aflix my signature.

FERDINAND HANFF.

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