US1691725A - Method of producing metal tubes - Google Patents

Description

Nov. 13, 1928. 1,691,725

- W. LEIGHTON METHOD OF PRODUCING METAL TUBES Filed Sept. 30, 1926 7 5.43 L m 7 L15 I 5 s a lnvehtor.

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Patented Nov. 1 3, 1928.

Joint wxcmrrn LEIGI-ITON", or roar URON, MICHIGAN.

" mn'rnon or raonucme marlin TUBES.

Application filed September 30, 1926. Serial No. 188,675.

The principal objects of the invention are, to enable the production of metal tubes by extrusion in large quantities and at low cost, and to devise a simple and effective means 5 for extruding metal billets.

The principal feature of the invention consists in the novel method of partly extruding the metal of the billet from a die and completing the operation by the progressive extrusion ofa portion of the succeeding billet.

In the drawings, Fi ure 1 is an elevational part sectional view of a set of dies showing a partly extruded billet and a heating torch arranged toapply heat to the partly ex- 1 truded billet.

Figure 2 is an elevational part sectional view of a-set of dies showing a succeeding billet placed therein upon a partly extruded billet. r

Figure 3 is an elevational part sectional view of the dies showing the succeeding billet partly extruded and completing the extrus1on of the preceding billet.

In the manufacture of short length tubin from prepared billets by extrusion method%,, numerous forms have been devised but difliculties have been encountered in the maintenance of the tools and in proper clearing of the dies after each operation. he

present method overcomes the objections that have been met with.

In the method of extruding billets to form tubes it has been found necessary to form the die with a bevelled bottom wall so that the metal may flow smoothly into the smaller diameter orifice. It is impossible to construct a punch which will successfully perform the operation of extruding the ma terial of the billet through the finishing ori- Accordin to the present method the die 1 is forms with a recess 2 of a diameter sligitly greater than the billets that are use The bottomwall 3 of this die converges to the diameter of the orifice 4 which is the full diameter of the finished tube.

The billets 5 used are of cylindrical form is a pilot 8 which is the same diameter as the inner diameter of the finished tube and is adapted to extend axially through the orifice 4 to form a throat through which the metal of the billet is forced.

Inthe forming of a length of tube in this die a heated billet is placed in the die and the punch is moved downwardly until the pilot extends through the central orifice thereof and the end of the punch closes the gie access,- the pilot extending into the orice y A continued movement of the punch. causes the metal of the billet to flow around the pilot and inwardly in the convergent die recess to the throat surroundin the pilot.

The method thus forms a tu e of the de sired diameter and thickness. v

The punch which is shown square across the bottom end in order to obtain the proper result in the flowing of the metal of the billet, cannot follow the metal past the upper shoulder of the tapered end of the recess,

consequently the metal is not completely extruded.

An annular recess 9 is formed in the side wall of the die recess whichv retains a narrow rib of the upper edge of the metal of the partly extruded tube and this rib of metal forms a positive lock to holdthe partly finished tube in the die allowing the withdrawal of the punch and its pilot clear there from.

After the punch has been withdrawn 9. suitable torch 1O swings over the die recess and a flame is directed downwardly against the upper end of the partly extruded tube. This flame which may be very hot is con-' tinued for a suflicient length of time to maintain the desired temperature of the upper part of the metal and the torch is then withdrawn and another heated billet is dropped into the die. The punch then descends into the die and the force exertedagainst the billet first causes the metal of the former billet to flow until the tube is completely extruded. The punch continuing further to descend causes the next billet to be extruded in a similar manner to the foregoing one.

The process thus described is continued indefinitely, each billet being reheated inthe die following the initial extrusion of the major portion thereof.

This method of manufacturing short length tubes has proven to be very successful i and the cost of manufacture is reduced to the minimum.

What I claim as my invention is 1. A method of extruding metal tubes,

5 consistin in placing a heated billet in a die,

then part y extruding the same from the die, by means of a punch, then withdrawing the punch, leavin the partly extruded billet in place, then re ieating the unextru-ded portion 1 of the metal, then placing a heated billet in 15 partial extrusion of said heated billet. t

2. A method of extruding metal tubes,

consisting in placing a heated billet within a die having a taperin throat, then a plying pressure to force t e metal of the lllet through the throat, then directing a flame into the die toimpinge against the unextruded end of the billet, then inserting another heated billet on the top of the unextruded portion of the former billet, then applying pressure to the latter billet to force the heated extruded metal of the preceding billet through the throat of the die to complete the extrusion of the first mentioned billet andefiect a partial extrusion of the following billet.

JOHN WYOLIFFE LEIGHTON.

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