US2325498A - Die for electrical forging machines - Google Patents

Description

July 27, 1943. J. M. FLOYD DIES FOR ELECTRICAL FORGING MACHINES "Filed May 29, 1941 John MFZQz/Cl INVENTOR.

ATTORNE Y Patented July 27, 1943 DIE FOR ELECTRICAL FORGI NG MACHINES John M. Floyd, Shorewood, Wia, assignor to}. 0.

Smith Corporation, Milwaukee, Win, a corporation of New York l Application May 29, 1941 Serial No. 395,804

Claims. (01. 219-3) This invention relates to dies for electrical forging machines in which a cylindrical article is pushed into or through 'a set of split dies constituting electrodes and shaped to give the desired shape to the article,-the dies and artiwater cooled to control the heating obtained. They are mounted on a; supporting plate 9 at cle being rotated relative to one another during the process. 5 V g The principal object of the invention. is to provide a die construction which is of longer life and which will more efllciently form the article. One embodiment of the invention is illustrated in the accompanying drawing in which: Figure 1 is a front elevation of the dies;

Fig. 2 is a side elevation .of the dies; and

Fig. 3 is a longitudinal central section taken.

on line 33 of Fig.1.

The dies are formed intwo or more segments I and 2 spaced circumferentially to provide gaps 3 for the passage of electric heatingcurrent through the article 4 being formed, between the respective die segments. I

,The die segments are hollowed out to pr vide a die cavity having the desired shape toform the article.' The die cavity illustrated in-the drawing is shaped to form the nose on. a bomb lugs and have die inserts 5 of cast iron or some suitable hard wear resisting alloy to engage the article being formed. At present'the inserts are preferably constructed of a fine grained heat treated cast iron having a surface hardness of between 400 -and 450 Brinell.

The inserts 5 have their inner surfaces shaped complemental to one another to provide the die cavity and have their outer surfaces shaped as a frustum of a cone to engage the inner surface of the copper dies with a wedging action under pressure from the forming operation.

The back or inner end of each insert 5 is reversed in direction, and instead of being flat on a horizontal plane perpendicular to the axis of the die cavity the end is recessed toward the center where it has an opening to receive the pin 6 and insulation 1 surrounding the pin.

The die inserts 5 are held in place by clamps 8.bolted to the respective dies I and 2 atthe forward open end and bearing against the end of the inserts. The clamps 8 are set in diametrically opposed radial recesses in the ends of dies l and 2 and the respective inserts 5 so that the latter are prevented from turning relative to the dies under the influence of the rotating article 4.

The dies I and 2 are preferably hollow and the rear end and secured-thereto by' insulated screws i0 passing through the plate and into 7 the dies.

The dies I and 2 have corresponding radial projections II- at their opposed edges for rec'eiving insulatedbolts I2 which secure the dies together. I Transformer leads "are secured to the opposite dies by bolts II.

The conduction of the heating current from the copper dies through the inserts to the article may vary in different longitudinal regions due to the difference in thickness of the die inserts ,5 in different regions. It is desirable to have the thinner portion of the die insert adjacent theearly forming stage,- and the outer surfaceshould be straight so as to obtain a proper fit of the inserts in the die. Any'inisfit will cause very uneven flow of heating current to the article, and is therefore undesirable.

The die faces of the inserts 5 are disposed witlr a'gradual curvature longitudinally to give the required nosing in of the article 4. The complementary die faces are not truly circular at any one transverse cross section, but have their leading edges, as determined by the direction of rotation of article 4, recessed outwardly to relieve them from wear as the article engages the segment of the insert. The remainder of the die faces follows a true circle in cross section.

The invention is applicable to dies employed to upset the ends oftubes or to reduce the diameter of tubes and the like and it will be understood' that instead of a single pair of die segments, three or more die segments maybe employed.

Various embodiments of the invention may be employed within the scope of the claims.

Iclaim:

1. A die member of the class described constituting a segment complementary to one or more other similar segments, comprising a heat and electrically conductive base, and a wearresistant face insert secured against longitudinal and radial movement relative to said base, and

contacting uniformly therewith throughout to conduct heat from the article being formed to said base and electricity from said base to the article.

2. A die member of the class described constituting a segment complementary to one or more other similar segments, comprising a heat con- I ductive base, a wear-resistant face insert having its inner smaller end wedged in a recess in said base, a clamp at the outer end for securing said insert in said recess, and means preventing relative turning between the insert and the base.

3. A plurality of die members of the class described constituting complementary segments encircling a die cavity, comprising heat and electrically conductive bases having their inner surfaces iorming the frustum of a cone, and corre,-. sponding die inserts of wear-resistant material having their nuter surfaces forming the frustum of a cone to contact uniformly with the respective bases for receiving electric heating current therefrom and their inner surfaces shaped to provide the die cavity. I

4. A plurality of'spaced die members constituting complementary segments encircling a die cavity for receiving and forming a relatively rotating article of circular cross section, the die 20 faces of the respective segments having their leading edges as determined by the direction of rotation of the article thereagainst recessed radially outwardly and their trailing edges similarly determined engaging the article under pressure 1 to form the-same. w

5. A plurality of spaced die members constituting complementary segments providing a die metal and having die inserts in the face thereof for resisting wear, said die inserts being oi different thickness in diflerent longitudinal zones of the die and being less conductive than said highly conductive metal.

JO M. FLO.

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