US2190828A - Method of casting - Google Patents

Description

Feb 20, 1940` L. s. DElTz, JR., Er AL 2,190,828

METHOD OF CASTING Filed Aug. 24, 19:55

FIG. 2.

A from/5y Patented Feb. 20, 1940 UNITED STATES PATENT oFFlci:

METHOD OF CASTING New York Application August 24, 1935, Serial No. 351,688

6 Claims.

This invention relates to a method of casting and more particularlytoa method of castingbillets of the grade of copper known in the art as tough pitch copper and peculiarly suitable for use in the production of copper rod, copper wire or copper tubing by rolling and drawing operations.

It has been found desirable in some instances in the art of manufacturing copper rod, copper wire or copper tubingl to have billets of uniform cross section throughout their length with which to begin the operations for producing copper rod and wire. terial of the billets have the physical and electrical properties of tough pitch copper. Tough pitch copper is a grade of metallic copper well known in the copper refining art under that name. v

An object of the present invention is to provide a method of casting billets of metal and particularly for casting substantially cylindrical tough pitch copper billets of uniform cross section and of suitable physical and electrical properties for rod and Wire, and with a smooth surface substantially free from porosity and seams.

In one embodiment of the invention, a mold is used whose body is itself cast from tough pitch copper with an axial cylindrical mold cavity within the walls of which is a helical bore. In casting billets therein, it is found that by pouring the molten metal to be cast with the mold at a temperature of 20D-400 F. allowing the metal to solidify and then running cooling water through the bore, the mold and billet are both cooled without effecting distortion or warping of the `35 mold, the billets may easily be removed from the mold, and the mold is left at a suitable temperature for immediate reuse. By emptying the bore of cooling water before pouring the charge and by not admitting water tothe bore until the charge has set, one important source of dangerous explosions is eliminated. It is found that satisfactory molds can be 4cast in a cast iron master mold with a rod of graphite or other sultable material as a core and with a helix of iron pipe cast into the walls of the copper mold thus produced to provide the cooling water channel or bore.

Other objects and features of the invention will appear from the following detailed descripin connection with the accompanying drawings `in which the same reference numerals are applied to identical parts in the several figures and in which 55v Fig. 1 is a view in side elevation and partly in It is further desirable that the ma-v tion of one embodiment of the invention taken.

Fig. 5 is a detached View of a modified form of 10 core for use in the master mold.

In the embodiment of the invention herein disclosed, a master mold (Figs. 2 and 3) has a cylindrical body 20 of any suitable material, cast iron having been found satisfactory, which is formed with an inner axial cylindrical mold cavity 2| of diameter equal to that of the exterior of the copper molds to be cast therein. The body 29 is supported on,v and if necessary may be secured (by means not shown) to a suitable base 22 having a fiatupper surface on which the body rests, and formed with a cylindrical recess 23 coaxial with the cavity 2|. The base 22 is also formed with a cylindrical perforation 24 for a purpose to be described later. A rod like cylindrical core 25 is positioned coaxially in the cavity 2| and is formed at its bottom end with a reduced stub 26 which lits into the recess 23 and so is held rigidly in place. This core 25 is of any suitable material, solid graphite as shown in Fig. 3 having been found to be satisfactory, or a cylinder of copper cast around a cooling coil as shown in Fig. 5 may be used.;

A top or lid 21 in the shape of a circular plate or disc, which may be of cast iron, rests on spacing means 49 on the upper end of the body and is held against movement by any appropriate means such as pins 23 passing through appropriate holes in the disc and in the spacing blocks 49 and into corresponding bores in the body 29. The disc is provided with a central aperture 29 which fits snugly around the upper end of the core 25 to hold the core rigidly in place. The disc is also formed with two appropriate apertures 39 and 3|, through which molten metal may be poured into the mold. A perforation 32 is formed in the disc about half-way between the center and periphery for a purpose to be described later.

A pair of semicircularly arcuate bands 33 and 34 is clamped about the top of the body, as shown, by bolts 35 and 3G and supports a gooseneck 3T extending upwardly from the bands and radially inwardly over the disc, which ends over the perforation 32 where it is provided with clamping means 38.

In operation, the master mold is'assembled as shown in Figs. 2 and 3 with a helix 39 of iron n pipe positioned therein as shown in dotted lines.

',Ihe ends of the helix 39 extend longitudinally, one being located to extend down through the perforation 24 of the base 22, and the other being located to extend up through the perforation. 32 of the disc and to be clamped by the means 38 on4 the gooseneck 31 and be additionally supported thereby. The coiled part of the helix 39 extends spirally and co-axially throughout the annularly cylindrical mold cavity between the inner wall of/the body 20 and the outer face of the core 25.

Preferably, the core 25 is painted or dusted before being put in place with a suitable material. The electrically sintered aluminum oxide product commercially known as alundum is satisfactory for this purpose. The interior of the body and base of the mold may also be covered with suitable material such as bone ash or alundum if found desirable. The bone ash or alundum is preferably suspended in water, painted or sprayed on, and dried. u

The master mold thus prepared and assembled is then lled with molten copper or copper alloy, poured through the apertures and 3|, which is then allowed to cool and harden with the helix 39 of iron pipe .embedded therein. When removed from the master mold the product thus pro duced is the body 40 of a Working mold for producilng billets. Such a body 40 is illustrated by itself in Fig. 1 and assembled with other parts to form a complete working mold in Fig. 4. This body consists of an annular cylindrical mass of copper having a cylindrical outer surface and a coaxially positioned cylindrical mold cavity 4I, the helix 29 of iron pipe being embedded coaxially within the copper Wall of the mold, with the extended ends of the helixprotruding respectively above and below the ends of the copper Wall. The surface of the mold cavity 4l may be machined to be smooth and polished if desired.

form, so only that its upper surface be shaped v to form the bottom of the cavity 4i The base 42 is also formedwith .a perforation 43 throughA which the bottom .end of the helix 39 passes forV connection to a water waste means not shown. Similarly the upper end of the helix is connected to a water supply, also not shown. A pouring funnel 44 having legs 45 may be set loosely on the top of the mold if desired; and-the molten metal poured from a ladle 46.

In starting the process of casting billets by means of the mold shown in Fig. 4, Vthe mold 40 is heated by any suitable means, such as a blow torch, until it is at an optimum temperature between 200-400" F., then the molten tough pitch copper for a billet is poured into the mold and allowed to solidify. After the solidication, cooling water is led through the helix 39, the billet is removed and the cooling continued until the mold reaches an optimum temperature between 200 and 400 F. The above mentioned optimum,v

Itisl lowing the casting to set and then cooling by a stream of water passing through a tube embedded Within the body of the mold, the cast billets produced are substantially completely homogeneous and in particular are free from porosity and from seams or wrinkles in the cylindrical side wall and at bottom of the billet. Only the top surface of the billet, which is a free surface, i. e., not formed against any wall, may have the faint wrinkling and defects characteristic of such a free surface; and as this is of relatively small area, the cropping required by its presence is of small volume. Hence this method or process of casting which includes pouring in a mold preheated to an optimum temperature, solidifying, and then cooling the mold walls by means embedded therein is found to produce billets of superior homogeneity and external freedom from surface flaws without inducing warping of the mold. The fact that there is no Water in any part of the mold sively in turn past stations where the charge is poured, the charge is allowed to set, the mold and contents are cooled, the nished billet is withdrawn, and the mold is ready for reuse.

It is also to be noted that the use of the alundum coated graphite core 25 or the Water cooled metal core 41 in the master mold Figs. 2 and 3) produces a casting for the body 40 of the working mold (Figs 1 and 4) of a dense homogeneous and generally flawless nature near the surface of the mold cavity 4 I, such that the subsequent machining to exact size may be minimum in amount and produces a smooth, ne textured and unawed surface eminently adapted to give billets cast therein a similarly smooth and unflawed surface. In fact in some instances itis found, especially when the water cooled metal core is used, that. the inner surface of the mold body as cast is suiciently smooth for use without subsequent machining.

By the use of cooling water within the body of the working mold in the manner and at the time described in the process of casting billets, it is found that the working molds do not tend to warp and thereby to render it impossible to withdraw the billets from them as is sometimes the case when similar molds without the inner cooling passage have .been cooled by application of water or other cooling agents externally.

Also it is to be noted that no cooling water is ever introduced, in this process, into the mold cavity 4|, a method which has in some cases produced disastrous explosions when similar molds have been cooled after being emptied by application of water simultaneously within and without to avoid warping, and then a new charge has been poured with water still in the mold. Also since the bore for cooling water is emptied before the charge of molten metal is poured and water is not admitted thereto until the charge has set, if by chance the mold Wall becomes cracked for any reason so that molten metal is admitted to theA bore, still the chance of explosion is mini mized by the absence of water from the bore at that time.

While thedevice herein disclosed is an annularly cylindrical mold for casting cylindrical billets, the invention is not limited to such but may be applied in the production of billets having square, oblong, oval, or other cross sectional shapes as may be desired.

The embodiment of the invention disclosed above has been described as applied to the manufacture of billets of tough pitch copper. Obviously the invention is not so limited but may be applied in the manufacture of billets of other grades of copper and of alloys of copper, and also of billets of other metals and alloys as well.

The embodiment of the invention herein disclosed is illustrative only and may be departed from and modified in many ways without departing from the spirit and scope of the invention as pointed out in and limited only by the appended claims.

What is claimed is:

1. The method of casting articles in a mold having a channel within the body of the mold which method comprises the steps of pouring molten metal into the mold while the said channel is empty of fluid, allowing the charge in the mold toI solidify, withdrawing the cast article from the mold, passing a cooling uid through the channel in the body ofthe mold to bring the mold to a predetermined temperature, emptying the cooling iiuid from the channel and repeating the sequence of operations.

2. The method of casting articles in a mold having a channel within the body of the mold, which method comprises the steps of pouring molten metal into the mold while the said channel is empty of fluid, allowing the charge in the mold to solidify, passing a cooling fluid through the channel in the body of the mold to bring the mold to a predetermined temperature, and withdrawing dthe cast article from the mold.

3. The method of casting copper articles in a mold of copper having a channel within the body oi the mold, which method comprises the steps of bringing the mold to a temperature between 200 F. and 400 F., pouring molten copper into the mold while the said channel is empty of water, allowing the charge in the mold to solidify, passing Water through the said channel, and withdrawing the cast article from the mold.

4. The method of casting copper articles in a mold of copper having a channel within the body of the mold, which method comprises the steps of bringing the mold to a temperature between 200 F. and 400 F., pouring molten copper into the mold while the said channel is' empty of water, allowing the charge in the mold to solidify, withdrawing the cast article Afrom the mold, passing water through the said channel to restore the mold to a temperature between 200 F. and 400 F., emptying the water from the channel, and repeating the sequence oi.' operations.

5. The method of casting articles in a mold having a channel within the body of the mold, which method comprises the steps of bringing the mold to a predetermined temperature, pouring molten material into the mold while the channel in the body of the mold is empty, and subsequently passing a cooling fluid through the channel to bring the mold again to the predetermined temperature.

6. The method of casting articles in a mold having a channel within the body of the mold, which method comprises the steps of pouring molten material into the mold only while the channel in the body of the mold is empty, and passing a cooling fluid through the channel in the body of the mold only after molten material poured into the mold has set, so that at no time is there molten material within the mold and cooling fluid within the channel in the body of the mold at the same time.

LOUIS S. DEITZ, JR. HANLEY H. WEISER.

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