US2755926A

US2755926A - Method of extruding elongated members

Info

Publication number: US2755926A
Application number: US330284A
Authority: US
Inventors: Horn Heinz
Original assignee: Felten and Guilleaume Carlswerk AG
Current assignee: Felten and Guilleaume Carlswerk AG
Priority date: 1953-01-08
Filing date: 1953-01-08
Publication date: 1956-07-24
Anticipated expiration: 1973-07-24

Description

July 24, 1956 H. HORN 2,755,926 METHOD OF EXTRUDING ELONGATED MEMBERS Filed Jan. 8, 1953 2 Sheets-Sheet 1 INVENTOR. f/f/A Z fiOR/V July 24, 1956 H. HORN 2,755,926 METHOD OF EXTRUDING ELONGATED MEMBERS Filed Jan. 8, 1953 2 Sheets-$heet 2 INVEN TOR. HE/A Z HORN EEQW W 2,755,926 METHDD F EXTRUDING ELONGA'I-TED MEMBERS Application January 8, 1953, Serial No. 330,284 6 Claims. (Cl 207---') Elongated extruded members such. as rods, tubes, structural and other shapes have customarily been manufactured heretofore by means of ram extrusion presses. The material of which the extruded member is to be made is inserted in the form of a solid billet into the container or receiver of the press and extruded through a die under the pressure exerted by a ram which is usually hydraulically operated. Even though the billet itself is freeof air and gas inclusions it is frequently ditficult to obtain a blister-free product because of the air inclusions which take place during the extrusion process because of the initial radial expansion of the billet by the ram pressure. This radial expansion presses the billet material solidly against the wall of the receiver so that air is entrapped which forms blisters in the extruded product. The blistering effect is most pronounced when the initial radial expansion takes place at the ram end of the billet so that a maximum amount of air is entrapped. Such blistering is particularly obnoxious when the extruded member is a sheath of aluminum or other metal or alloy having a higher melting point than lead such as is used to protect an electrical cable wherein the imperviousness to moisture is of particular importance.

Objects of this invention are to provide a method for making extruded members substantially free from air inclusions, which is particularly adapted for making sheathing for electrical cables, which can be carried out without modification of present equipment, which does not require special tools or skills, and which advances the art generally.

These and other objects will be apparent from the following detailed description of the process which refers to the drawings wherein:

Figs. la, 1b, 1c and 1d are diagrammatic longitudinal sectional views of a press for making an extruded member having a solid cross section;

Fig. 2 is an isometric view of a billet for the press shown in Fig. la;

Fig. 3 is a diagrammatic longitudinal sectional view of a press for making a hollow extruded member; and

Fig. 4 is an exploded isometric view of a billet for the press shown in Fig. 3.

In Fig. la are diagrammatically shown the essential elements of an extrusion press such as is well known in the art so that they need not be described further other than to say that 10 represents the receiver having a bore wherein is reciprocatingly disposed a hydraulically operated ram 12, the end of the bore opposite that through which the ram enters being closed by an apertured die 14 of a Wearresistant material. When the above described press is used in the conventional manner, the ram 12 is withdrawn from the bore of the receiver 10 and the bore loaded with a cylindrical billet having a diameter slightly less than the bore and a length great enough so that it substantially fills the bore. The ram then is brought into contact with the end of the billet exerting a high pressure thereupon so that the material of the billet flows out through the aperture in the die 14.

States Patent 0 As mentioned heretofore, with a long billet the end thereof nearest the ram expands first in a radial direction trapping a considerable amount of air along the length of the billet which causes blisters and inclusions in the extruded product. I overcome defects caused in the above manner by first inserting in the bore of the receiver 10 a relatively short billet B whose length is preferably less than one and one-half its diameter as is shown in Fig. la. The second step is to expand the billet in a radial direction by operation of the ram 12, as is shown in Fig. 1b, the short length of the billet reducing the amount of air trapped during such radial expansion. Successive short billets B, B", B', are sequentially inserted and expanded radially by the ram 12, as is shown in Fig. 10, untilthebore of the receiver 10 is filled whereupon the material of the billets is extruded in an elongated member M which minimizes the air blisters and inclusions, as is shown in Fig. 1d.

The above described process is particularly applicable to the extrusion of material such as aluminum alloys for electrical cable sheathing wherein the imperviousness to moisture and water is of the greatest importance. As is shown in Fig. 3,. an insulated electrical conductor C is fed through a hollow mandrel 16 so that the end thereof passes through the aperture in the die 14. The mandrel 16 which is relatively stationary with respect to the die 14 and the receiver 10, passes through an aperture in the ram 18. It is therefore necessary to provide billets in the shape of an annulus or ring to accommodate the mandrel 16 rather than cylindrical billets B such as were used in the embodiment shown in Figs. la to 1d. To facilitate inserting of the billets in the bore of the receiver 10, each billet is preferably provided with two or more radial cuts so that it is divided into several sectors as is shown in Fig. 4.

The process for making hollow members or sheathing is carried out in a manner analogous to that described heretofore. The receiver 10 is charged by inserting the sectors which comprise one of the billets S and expanding the inserted billet by means of the ram 18 so that the air in the interstices between sectors and between the sectors and the receiver wall can escape as the billet is expanded. Succeeding billets S are inserted one at a time and expanded until the receiver bore is filled. The ram 18 then is used to force the billet material out through the space between the die 14 and the mandrel 16 so that a sheath is formed which surrounds the cable C as it is fed from the mandrel at the same rate that the sheath is extruded.

I claim:

1. The method of extruding an elongated member substantially free from gas inclusions comprising the steps of inserting a plurality of short billets in the receiver of an extrusion press in the number required substantially completely to fill the receiver, expanding each of the billets by the operation of the press ram before the succeeding billet is inserted to bring the periphery of the inserted billet into contact with the wall of the receiver, and after the receiver is filled operating the ram to extrude the material of the billets through the die of the press to form the elongated member.

2. The method of extruding an elongated member substantially free from air inclusions comprising the steps of inserting in the receiver of an extrusion press a billet whose length does not substantially exceed its diameter by more than one and one-half times, deforming the billet in a radial direction by the operation of the ram of the press until the entire periphery of the billet is in contact with the wall of the receiver, withdrawing the ram from the receiver, repeating the above defined steps to insert and deform a plurality of billets in the number required substantially completely to fill the receiver, and subsequently operating the ram to extrude the material of the billets through the die of the press to form the elongated member.

3. The method of extruding a hollow elongated member substantially free from gas inclusions comprising the steps of inserting about the mandrel in the receiver of an extrusion press an annular billet whose length does not sub stantially exceed its outer diameter by more than one and one-half times, deforming the billet in a radial direction by the operation of the ram of the press to bring the outer and inner peripheries of the billet into contact with the walls of the receiver and mandrel respectively, repeating the above defined steps to insert and deform a plurality of billets in the number required substantially completely to fill the receiver, and subsequently operating the ram to extrude the material of the billets through the die of the press to form the elongated member.

4. The method of extruding a hollow elongated member according to claim 3 including the further step of dividing each billet into several sectors to facilitate the insertion thereof in the receiver.

5. The method of extruding a sheath for an electrical cable substantially free from air inclusions comprising the steps of inserting about the hollow mandrel of an extrusion press an annular billet Whose length does not substantially exceed its outer diameter by more than one and one-half times, deforming the billet in a radial direction by the operation of the ram of the press to bring the outer and inner peripheries of the billet into contact with the walls of the receiver and mandrel respectively, repeating the above defined steps to insert and deform a plurality of billets in the number required substantially completely to fill the receiver, and subsequently operating the ram to extrude the material of the billets through the die of the press to form the sheath about the wire as it is pulled through the mandrel.

6. The method of extruding a sheath according to claim 5 including the further step of dividing each billet into several sectors to facilitate the insertion thereof in the receiver.

References Cited in the file of this patent UNITED STATES PATENTS 529,215 Tatham Nov. 13, 1894 571,332 Bicheroux Nov. 17, 1896 1,654,526 Brown Jan. 3, 1928 1,720,722 Dean July 16, 1929 2,639,809 Perry et al May 26, 1953 FOREIGN PATENTS 415,359 Great Britain Aug. 23, 1934 657,185 Great Britain July 12, 1951 873,080 France June 29, 1942

Claims

1. THE METHOD OF EXTRUDING AN ELONGATED MEMBER SUBSTANTIALLY FREE FROM GAS INCLUSIONS COMPRISING THE STEPS OF INSERTING A PLURALITY OF SHORT BILLETS IN THE RECEIVER OF AN EXTRUSION PRESS IN THE NUMBER REQUIRED SUBSTANTIALLY COMPLETELY TO FILL THE RECEIVER, EXPANDING EACH OF THE BILLETS BY THE OPERATION OF THE PRESS RAM BEFORE THE SUC-