US2738873A

US2738873A - Manufacture of practically endless extrusion products

Info

Publication number: US2738873A
Application number: US475984A
Authority: US
Inventors: Emmerich Ernst
Original assignee: Schloemann AG
Current assignee: Schloemann AG
Priority date: 1953-12-22
Filing date: 1954-12-17
Publication date: 1956-03-20
Anticipated expiration: 1973-03-20

Description

March 20, 1956 E. EMMERICH 2,733,373

MANUFACTURE OF PRACTICALLY ENDLESS EXTRUSION PRODUCTS Filed Dec. 17, 1954 2 Sheets-Sheet l it, 0 11mm? 1 fiebdae March 20, 1956 E. EMMERICH 2,738,373

MANUFACTURE OF PRACTICALLY ENDLESS EXTRUSION PRODUCTS Filed Dec. 17. 1954 2 Sheets-Sheet 2 United States Patent MANUFACTURE OF PRACTICALLY ENDLESS EXTRUSION PRODUCTS Ernst Emmerich, Koln-Eruck, Germany, assignor to Schloemann Aktiengesellschaft, Dusseldorf, arm-any Practically endless extruded rods, tubes, cable sheaths and the like can be manufactured upon ,discontinuously working extrusion presses, with the interposition, during the pressing, of pauses in which the press ram is retracted and fresh material is inserted, in the form of a billet for example. In this manner, also, cables can be sheathed with lead or aluminium.

This process has however the disadvantage that'at intervals upon the extruded product so produced sofcalled bamboo rings appear, in the region of which the thickness of the product is reduced, or at least the extruded material exhibits a structure different from that of the remainder. These bamboo rings occur from time to time when one stroke of the press is terminated and the press ram is retracted to enable fresh material for extrusion to be introduced; for at this moment the pressure bearing upon the material diminishes, and this is .what leads to the formation of the so-called bamboo rings.

The disadvantages of these bamboo rings become particularly noticeable in cable sheaths, because in practice cables have to be of indefinite length, and furthermore have to be wound upon a drum or the like. The position of the bamboo ring therefore represents a weakening of the cable sheath, which is felt to beparticularly disadvantageous when the cable sheath is repeatedly bent. just at this point. Severe bending stresses are therefore more liable to lead to breakage at the position of the bamboo ring than equal stresses would be at any other point of the cable sheath.

The object of this invention is to obviate or reduce the disadvantages of the bamboo rings, and the invention consists in imparting to the bamboo ring that is formed between two strokes of the press, by means of suitably-constructed tools, a formation which lies outside any plane which is perpendicular to the axis of the press. The barnboo ring upon the tube or the cable sheath may for example be given an elliptical form. It will then lie in a plane which is inclined to the axis of the cable. A construction also appears advantageous in which the bamboo ring represents upon the cable sheath or the tube a double sinusoidal line.

The tools for carrying out this process are characterised by the fact that the rod-forming zone of the die is wholly or partly oblique to any plane perpendicular to the axis of the press. In the case of tools consisting of a mandrel and a die for the production of hollow extrusion-press products, preferably of tubes and cable sheaths, the rodforming gap is preferably so constructed that it is inclined to the axis of the press. In order to obtain the abovementioned sinusoidal bamboo line, tools may also be employed in which the rod-forming gap has the shape of a sine curve marked upon a cylinder.

The formation of the bamboo ring according to the invention is also, in many kinds of cables, of electrotechnical importance, particularly in so-called concentric high-frequency cables. In these the aluminium sheath serves at the same time as a return conductor. At rather high frequencies the circular bamboo ring of ,the usual shape then has a very prejudicial efiect as a point of reflection. This is obviated, or at least diminished, if the bamboo ring is produced according to the process of this application, that is, if it no longer lies in a plane perpendicular to the axis of the sheath.

Theinvention is illustrated by way of example in the accompanying drawings, in which:

Figures 1 and 3 show developed tube peripheries;

Figures 2 and 4 show outside views of the tubes; and

Figures 5, 6 and 7 show in axial section tools that may be employed for putting the invention into practice.

Figure 1 shows a developed tube periphery 1, in which the bamboo ring 2 is of sinusoidal shape. This shape of the bamboo ring obviates the risk of breakage of the sheath 1. Figure 2 shows the same cable sheath in elevation. Figure 3 shows the development of a periphery 3, which is represented in elevation in Figure 4. The bamboo ring 4 is here located in a plane which is at an inclination to the axis of the sheath 3.

Figure 5 shows a chamber die consisting of a die memher 6; and an upper member 7. These two members are undisplaceable relatively to one another owing to centering rings 8. The die 6 has an elliptical edge 9, which lies in a plane that is not perpendicular to the axis of the press. The mandrel tip 10 has a corresponding elliptical shape, so that between the die and the mandrel there is a gap 11 of substantially constant breadth, 'the plane of which is inclined to the axis of the press. This gap therefore forms a bamboo ring of the shape shown in Figure 4.

Figure 6 shows a die 12 and a mandrel tip 13. This mandrel tip may be displaceable and adjustable in the direction of pressing realtively to the die 12, for the pur pose of producing sheaths of different thicknesses. Such tools are employed on an ordinary tube-extruding press with an adjustable mandrel. Since the mandrel 13 is hollow, a cable can be sheathed with tools of this kind.

Finally Figure 7 shows a tool with which bamboo rings substantially as shown in Figures 1 and 2 can be produced. The mandrel tip 13a has here, like the die 1201, a sinusoidal edge bounding the gap 14.

The invention can also obviously be carried out with differently constructed tools, for instance tools in which the mandrel tip is of V-shaped construction, and the die is adapted to this V-shape.

I claim:

1. A method for the production of practically endless extruded rods, tubes, cable sheaths and the like upon discontinuously working extrusion presses, characterised by the feature that to the so-called bamboo ring that forms between two strokes of the press there is imparted a shape which lies outside any plane perpendicular to the extrusion axis.

2. A tool for the production of practically endless extruded rods, tubes, cable sheaths and the like upon discontinuously working extrusion presses by the method claimed in claim 1, characterised by the feature that the rod-forming zone of the die is at least partly oblique to any plane perpendicular to the axis of the press.

3. A tool as claimed in claim 2 for the production of hollow extrusion-press products, preferably tubes and cable sheaths, characterised by the provision of a mandrel and a die, separated from one another by a rod-forming gap situated at an inclination to the axis of the press.

4. A tool as claimed in claim 2 for the production of tubes and cable sheaths, characterised by the provision of a mandrel and a die, separated from one another by a rod-forming gap which has the form of a sinusoidal curve marked upon a cylinder.

No references cited.