US2538918A - Die for the extrusion of metals - Google Patents

Description

H951 J. SEJOURNET ET AL 2,538,913

DIE FOR THE EXTRUSION OF METALS Filed June 5, 1945 2 Sheets-Sheet l INVENTOR 5 e 6, Jean Bonnassmux P? MM 48%, JZ

dacqu s Jg/oamezfana Jan. 23, 1951 J. SEJOURNET ET AL 2,538,918

DIE FOR THE EXTRUSION 0F METALS Filed June 5, 1945 2 Sheets-Sheet 2 ENVENTORS dacqaesqgsyoumezfana dean B lmass/eux Patented Jan. 23, 1951 DIE FOR THE EXTRUSION OF METALS Jacques Sejournet, Paris, and Jean Bonnassieux, Les Fontaines dUgine, France, assignors to Comptoir Industrlel dEtirage et Profilage de Metaux, Paris, France, a corporation of France Application June 5, 1945, Serial No. 597,650

In France September 15, 19M

1 Claim.

In the U. S. patent application Ser. No. 597.266, of June 2, 1945, and now abandoned, improvements in the extrusion, thru an extruding press, of metals in a heated state have been described. which consist in inserting between the metal ingot, brought to a high temperature, and the tool implement, an incombustible material melting partially or totally under the action of the heat of the ingot and of the implement, but showing and retaining, when so melted. a viscosity which is sufliciently high for this mate rial to form, between the ingot and the implement, a lubricating layer which flows with the metal in the course of the extruding operation. Glass, oxides, salts and natural or synthetic slags, answering the above mentioned conditions. can be chosen to this effect, said materials being advantageously used in the form of plates set in between the ingot and the die.

In said application, attention has been drawn to the fact that, in certain cases. the breaking of such plates between ingot and die in the beginning of the extruding process may lead to an irregular lubrication. an important fraction of the incombustible material being ejected thru the die in front of the extruded metal. In order to avoid such irregularities, it has been recommended to provide the surface of the die which comes into contact with the ingot, with cavities or recesses in which reserves of melted lubricating material can be formed.

However, in certain cases, such a measure may not be sufiicient to insure a perfect lubrication of the die. This occurs particularly when the extruded bars show a polygonal cross section with a low number of sides, i. e. three or four sides for instance, or when the angles of the cross section of the die are close to the edges of the die block, or, further, if the profile shows re-entering angles. The lubricating material is then irregularly distributed, lubrication being insumcient in the middle region of the longer sides of the cross section of the extruded bar. and in the re-entering angles, by the fact that the lubricating film diminishes in said parts. Such irregularities entail sticking of the extruded metal on the die, gripping, carrying away of the metal of the die by the extruded metal, said die being in any case rapidly worn and put out of use.

The dies generally used up to now for the extrusion of metals comprise a converging entrance zone, the generating lines of which are usually formed by an arc of to about mm. radius, this entrance zone being followed by a cylindrical or prismatical part known as the bearing of the die, of constant height and the cross section of which corresponds to that of the bar which is to be extruded. The bearing is followed, on the exit side of the die, by an open zone which may show difierent forms, for instance that of a cylinder or of a cone.

Instead of such dies, and to avoid irregular lubrication in the above mentioned conditions, one may use, according to the present invention. a die the bearing of which shows a variable height in the different parts of the profile, this height being the smaller, in a determined zone, the more diificult the latter is to lubricate, the radius of the entrance zone being practically the same in all the points of the profile.

The height of the bearing can vary stepwise, three different heights being generally enough in most practical cases. It is also possible to confer to the bearing regularly increasing or decreasing heights, but the industrial realization of such dies is much more difiicult and experience has proved that they do not show any marked advantage.

To determine precisely the zones of the bearing where the lubrication is insufiicient or more difficult to realize, one may proceed to a preliminary test excuted in the conditions in which the extrusion shall take place, but with a normal die the bearing of which shows a constant height; such a test shows immediately the insufi'iciently lubricated regions, for which a small height of bearing must be chosen, and the regions where lubricating is fair or good and in which the bearing can be chosen higher.

In a general manner, according to what has been set forth above, the height of the bearing must be minimum in the region of re-entering angles of the profile and in the middle region of the sides of polygonal profiles with few sides, and maximum in the protruding angles of the profie, the regions of maximum and minimum height being contingently linked by regions of intermediary height or heights.

In the appended drawings:

Figs. 1 to 5 represent different examples of cross sections of extruded bars.

Figs. 6 to 8 are sectional views of three dies of known type.

Figs. 9 to 11 represent diagrammatically the repartition of regions of various bearing heights for dies corresponding to the cross sections respectively represented at Figs. 1, 3 and 5.

Fig. 12 is a view on the exit side of a die with sesame 3 a. bearing of variable height according to the invention.

Fig. 13 is a sectional view thru line XIIIXIII of Fig. 12.

Figs. 14 to 16 are sectional views respectively thru )QV-XIV, XV-XV and XVIXVI of Fig. 13.

On the cross sections 01 bars represented at Figs. 1 to 5, the shadings indicate the regions in which the corresponding dies are particularly subject to wear following an insufficient thickness oi the lubricating film. Thus, when extruding a triangular bar (Fig. 1), the middle region of the sides of the triangle can be insufliciently lubricated. For a pentagonal bar, such as that of Fig. 2, the insufficiently luurlcated regions correspond to the middle part of the longer sides. For a bar showing a cross-section such as that of Fig. 3, the region neighbouring the re-entering angle and the opposite region are the most difficult to lubricate. The same occurs in right angle and T-shaped bars (Figs. 4 and 5).

In known type dies represented at Figs. 6 to 8, comprising an entrance zone i the lateral surface of which shows a radius of curve R, a bearing 2 the cross section of which corresponds to that of the bar to be extruded, and an exit zone 3, the height e of bearing 2 is constant all around for a same die.

0n the opposite, in the dies according to the invention, the height of the bearing varies from one region of the profile to another, said height, in a determined zone, being the smaller, the more diflicult said zone is to lubricate.

At Figs. 9 to 11, the bearing zones of maximum height have been indicated diagrammatically by heavy lines, the zones of minimum height by fine lines and the zones of intermediary height by medium lines. In a decreasing order, the bearing heights can, for instance, be the following:

e1=6 mm. ez=4 mm. es=2 mm.

In case oi a triangular die (Fig. 9), two ddierent heights are used, c1 and en, respectively of 6 mm. and 2 mm. for instance, height :21 corresponding to the three angles and e; to the middle regions 01' the sides.

For the cross section represented at Fig. 10, one adopts preferably three different heights. The smaller, as, corresponds to the re-entering angle and to the straight part opposite this angle. The greater, el, must be adopted for the extemai circular region and for the extremity of the rectangular part, the higher and lower zones being Joined by intermediary steps ea.

In the case of a T-shaped profile, the bearing zones of smaller height e: are those oi the re-entering angles and 01 the part 01 the wings opposite the latter, the zones of greater height e1, those of the wing and web extremities, the different zones being Joined by steps of medium height c2.

The die represented at Figs. 12 to 16 corresponds to the latter type.

What we claim is:

In a device for extruding a heated metal ingot through a die by means of an extruding press in which an incombustible material melting at least partially when in contact with the ingot is inserted between the latter and working parts of the extruding press, a die the height of the bearing wall of the die varying in the diflerent parts of the profile, said height being a maximum at the protruding angles and a minimum at the re-entering angles and middle regions of the sides of said profile.

JACQUES SEJOURNET. JEAN BONNASSIEUX.

REFERENCES CITED UNITED STATES PATENTS Name Date Webb Feb. 15, 1941 Number

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