US2894624A - Dummy block - Google Patents

Description

July 14, 1959 D. G. LEONARD 2,894,624

DUMMY BLOCK Filed Jan. 4, 1957 28 IN VEN TOR.

Dar/v15 6f leonaro HTTORN'EYS United States Patent DUlVlMY BLOCK Dorris G. Leonard, Ferguson, Mo., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Application January 4, 1957, Serial No. 632,487

1 Claim. (Cl. 207-9) This invention relates to dummy blocks for use with extrusion apparatus and particularly to dummy blocks which are adapted for use in the extrusion of light metals.

In the extrusion of metal sections from extrusion presses, a billet disposed in a container which abuts an extrusion die is upset by pressure exerted by a ram against a dummy block which fits more or less closely like a loose piston within the container bore between the ram and the billet to be extruded. As pressure is applied to the upset billet, metal from the billet flows through the die opening to form the extruded section.

Because the dummy block does not fit tightly within the container, a peripheral part of the billet, called flash, usually by-passes the head or billet end of the dummy block as the block is advanced towards the die end of the container. Conventional dummy blocks of the type heretofore used usually have two separate transversely disposed lands which keep the block centered in the container. Thus, when the flash passes the first land it tends to lodge in the transverse groove between the two lands, making a ring around the dummy block which must be chiseled away, usually after each push of the dummy block through the container.

The flash removing operation is not only time consuming but it involves the manual handling of hot metal with the attendant risk of burns to the handler.

Accordingly, a principal object of this invention is to provide an improved self cleaning dummy block for use in extrusion apparatus.

In accordance with this invention a dummy block is provided which is generally cylindrical in shape with a transverse land at or near its forward end and a plurality of longitudinal lands extending from the transverse land towards the rear of the dummy block. The longitudinal lands, of equal height, are generally disposed symmetrically around the outer side wall of the dummy block.

Additional objects and advantages of this invention will be apparent when the following detailed description is read in connection with the accompanying drawings, in which;

Fig. 1 is a side elevational view, partly in section, of extrusion apparatus which includes a dummy block made in accordance with this invention;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary elevational View, partly in section, which shows an alternative dummy block having longer longitudinal lands than does the block shown in Fig. 1;

Fig. 4 is a fragmentary elevational view showing a dummy block having a detachable longitudinal land;

Fig. 5 is a sectional view taken along the line 5-5 of Fig. 4, and

Fig. 6 is an isometric view of a dummy block made in accordance with this invention.

Referring to the drawings, particularly to Figs. 1 and 2, there is shown extrusion apparatus including a con- Patented July 14, 1959 ice tainer 10 having a bore 12, a die 14 and die backer 16 abutting against one end of the container 10. A dummy block, indicated generally by the numeral 18, is shown disposed within the bore 12 of the container 10. The dummy block 18, driven by a ram 20, is used to upset the billet 22 in the container 10, forcing the metal of the billet to flow through the opening 24 of the die 14 to form an extrude 26.

Referring to Fig. 6 as well as to Figs. 1 and 2, the dummy block 18 comprises a cylindrical body 28 of somewhat smaller diameter than the diameter of the bore 12 of the container 10. A transverse land 30 is disposed at the end of the block 18 which is to face the billet. The land 30 is usually of uniform width and of uniform thickness and is coaxial with the body of the block 18. A plurality of parallel, finger-like lands 32 are disposed longitudinally around the outer surface of the body 28 of the dummy block 18, the lands 32 usually, but not necessarily, being disposed in a symmetrical array. The number of longitudinal lands 32 varies between 3 and 8, although more than 8 lands may be used, if desired. The minimum number of longitudinal lands is that number of lands, which with the transverse land 30, will keep the dummy block 18 axially aligned with respect to the container bore 12. The width of each land 32 is usually a minor fraction of its length in order to decrease the friction between the dummy block 18 and the wall of the container bore 12.

The grooves or body surface between the lands is usually polished, to about 15 micro-inches r.m.s. finish, for example, to insure a smooth, even flow of the flash metal along the grooves. The junction 34 between the walls of the lands and the surface of the block body 28 is usually, but not necessarily, tapered in order to mini mize the buildup of flash material along the base of the lands and in the grooves. The longitudinally disposed lands 32 usually abut against or are integral with the transversely disposed end land 39.

In the modification of Figure 3, the numbering in Figures 1, 2, and 6 is continued with the exception that modified. parts are identified further with subscripts Thus, 18a is the dummy block as generally considered, 28a is the body of said block, and 32b is the land.

While normally the longitudinal lands 32 are an integral part of the dummy block, the longitudinally disposed lands may, as shown in Figs. 4 and 5, be separate elements 32a which are secured to the body of the dummy block. In the arrangement shown in Figs. 4 and 5, the land element 32a is adapted to fit into a keyway 36 which is in the body 28 of the dummy block 18. The land element 32a, which fits closely within the keyway 36, is secured to the dummy block body 28b by means of bolts 38. The arrangement of Figs. 4 and 5 permits worn land elements 32a to be removed from the dummy block 18b and replaced by un-worn elements.

While the land elements 32a are illustrated as extending from the transverse land 30a to the ram receiving end 40 of the dummy block, shorter elements may be used.

In operation, dummy blocks 18 made in accordance with this invention are substantially self-cleaning. As the dummy block 18 is pushed forward against the billet 22 a small amount of flash material by passes the transverse land 30 and enters between the longitudinal lands as thin strips. The strips of flash either fall from the dummy block 18 as the block 18 is Withdrawn from the container 10 or the strips are easily broken away from the block 18. Even in the larger size dummy blocks 18 the segments of flash material are easily removable from the block 18 without chiseling.

I claim:

A dummy block for use in extrusion apparatus in- J) eluding a container having a cylindrical bore and a ram adapted to be inserted into said bore, comprising a generally cylindrical body having a billet end, a ram receiving end and a side wall, said body having a transversely disposed land encircling the billet end of said side wall, the width of the transversely disposed land being a minor fraction of the overall length of the dummy block, and at least three longitudinally disposed lands, said longitudinally disposed lands being integral with said transversely disposed land and extending from said transversely disposed land towards said rarn receiving end of said body, the Width of the longitudinally extending lands being relatively narrow as compared with the distance between adjacent lands.

References Cited in the file of this patent UNITED STATES PATENTS Sejournet et a1. Feb. 28, 1956 Boccon-Gibod et ail. July 24, 1956 FOREIGN PATENTS Canada Aug. 8, 1950 Germany Mar. 16, 1933 Great Britain Oct. 27, 1954 France Oct. 17, 1951

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