US2200178A - Production of composite castings - Google Patents

Description

May 7, 1940.

1.. A.A KLEBER.

P'nonUcTIoN oF GMPosITE:l CASTINGS Filed March 8. 1938 Patented May 7, 1940 UNITED STATES PATENT oFElcE PRODUCTION F COMPOSITE CASTINGS Luther A. Kleber, High Bridge, 'N. J., assignor to Taylor-Wharton Iron & Steel Company, High Bridge, N. J., a corporation of New Jersey Application March 8, 1938, Serial No. 194,654

Claims.

'I'he invention provides certain improvements in composite castings and in the methods thereof and more particularly it provides for the production of tubular or hollow cylindrical shapes, com-Y l prising cylindrical sections, formed, respectively, of different metals joined end to end, in such way as to insure homogeneous union of the sections and in such way as to inhibit substantial penetration of the metal of one section into the metal 10 of the other section, meaning by that such interpenetration as may have the eiect of so alter- Y ing the characteristics of the section encroached upon as to render it unfit to perform the partickinds of service employing composite cast cylindrical shapes for which it is desirable, if not essential, to have denite lengths of different analyses. For example, the casting may be required to withstand high heat at one end and to conduct heat rapidly at the other end as when employed as an inner barrel in heat accumulator stoves `of the Aga type. Excluding certain comparatively rare and high cost metals, the metals capablerof withstanding high heat are otherwise not satis? factory because of their low rate of heat conduc- 3'5 tivity.

Recourse has been had to the riveting and otherwise mechanical connection of separate castings and they even have been welded together but there are many objections to such practice aside from the fact that they are not economical Itfhas been proposed to produce composite cast stove elements, such as inner barrels andthe like, by separately pouring, into one and the same mold, pig iron forming one cylindrical sec- 5 tion and ferrochromel forming the other cylindrical section, reliance beinghad upon a chill to, Ain effect, dam the ferrochrome and pretfyiit it from rising through the pig iron. 'I'his practice suiers the objection of lack of control of the 50 height and character of the line of merger betweenl tle two metals because the 'rst metal is poured to a point belowthe level ofthe chill so that the second metal encounters the chill before any welding can take place with the rst metal and, consequently, there is ever present the hazard of a poor weld especially since no provision is made for getting rid of impurities carried to the welding area by oney or both metals.

It is the purpose of the invention to obviate the difficulties and disadvantages of the conventional practice and, briefly stated, it provides a method and means whereby in the composite casting of inner barrels and the like some of one or the other or of both metals is permitted to ow oif at or adjacent their point of mergence for the purpose and with the result of iiushing away any impurities that may be present and which, if allowed to remain, would militate against sound welding, said iiowoff having as its main purpose and result the positive control of the composite casting operation by serving to establish the level of the weld within closely reckoned limits, that is to say', within about an inch 1/2 plus or minus of the theoretical).

It. is characteristic of the invention that it will insure the production oi' sound castings regardless of the presence `or absence of chills, whether internally or externally applied, and regardless of the compositions of the metals Y,to be joined. And yet, it is a merit of the invention that it admits of the use of `inserts or chills which I have devised in the nature of coils or helices of light strand wire which, while eiective in the performance of their chilling. office, oer no serious obstacle to metal flow but permit the metal to iiowfreely through the coils and about the strands so that for all practical purposes the wire is vfusedI and a cross section of the casting in the chilled area will show substantially solid metal. So also it is a merit of the invention that unusually good results follow the use of -the metal composition hereinafter stated. Y

The invention in its preferred embodiment will be described in connection witha the accompanying drawing in 'which 40 Figure 1 isa sectional view of the improved mold.

Figure 2 is-a section on line 2'-2 .of Fig. 1, showing the general construction 4and arrangement of one of the coil chills.

The mold 5 is equipped with separate pouring provisions 6 and 1 for bottom and top pouring. The practice heretofore has been first to pourv the ferrochrome through the pouring provision or gate ,6 and then to pour the pig metal or cast iron via the gate .1 and, while theorder and .metals may be reversed "according to the problem in hand, I adhere to that practice except that,. in any event, I provide lat a predetermined point in the common mold cavity Va. metal iiowoff 8. For

example, assuming the presence of a chill insert 9 in the bottom poured metal I0 the owoff is located above the chill but with or without chills, and regardless of the order of casting, the owoff 8 is arranged so that it will be effective to run off some of one or both metals to flush away impurities and to insure sound metal in the region of the consolidation or mergence of the two metals while controlling interpenetration. Suflicient amounts of both metals may be poured to insure a proper run off at 8, but it is manifestly more economical to rely principally on excess pouring of the baser metal as the ushing medium.

While the flow-off 8 is the dominating factor in controlling interpenetration of the separately cast metals, that is to say, fusion of the metals and a clean weld of sound metal within closely reckoned limits, for example within about an inch UA plus or minus of the theoretical) there are occasions in the quantity production of shapes when it is desirable to employ chills and the flow-off 8 admirably lends itself to coordination in that practice regardless of the form and arrangement ofthe chill or chills and whether they be inserts or applied in any other conventional way. However, when an insert is deemed expedient or desirable I find it good practice to employ one and preferably two coil chills arranged one above the other and so disposed that the metal first poured will be above the upper chill. Such chills are illustrated as rings 9 of helical or coiled iron wire. In the production of inner barrels, and the like cylindrical castings, I nd that wire of about .050 gage in the form of coils whose outside diameter is about %th" tobe adequate for the purpose. Coiled'wire chills are.v advantageous because they offer no serious check to metal flow to the desired level and yet accelerate the cooling rate so that there can be no excessive or undesirable interpenetration of the metals.

When applying my invention to the production of solid cast heat accumulator units, such as inner barrels, I prefer to employ metals of analyses substantially as follows, more or less,

The molten chrome cast iron is preferably poured first through the gate 6 whence it passes to the bottom of the mold and rises through the chills 9 to the level indicated by the line X which -is substantially the top level of the now-off 8.

The cast iron is then poured via the sow gate or pouring basin 1, and some'of it is permitted to flow away at 8 to displace some of the iirst poured metal,l to obviate the presence .of impurities, to insure sound metal in the zone of fusion and toL control the depth of interpenetration substantially within predetermined limits.v After suflicient lapse. of time to satisfy the requirements of such iiushing and control the flow-off 8 is plugged as at'll and the pouring 'of the cast iron is continued until the remainder of the mold cavity and the riser4 i 2 are lle'd.

above the coil or chill, the chrome cast iron is prevented from undesirably penetrating the cast iron and vice versa. The penetration is indicated at i3 and it is restricted to definite limits, as previously stated, the depth of penetration being a line in theplane of the upper level of the flowoff and, at any rate, above the chill.

While not essential to the practice of the invention, the presence of a chill Il in the top of the heavy cast iron section operates to improve the appearance of the eventually machined surface I5 through a reduction of graphite precipitation in the cast iron metal and by causing the graphite to precipitate in ne particles rather than in the form of coarse flakes.

In service, as stove heat accumulator units, long periods of high temperatures are alternately applied to the chrome cast iron section with no ill effects such as distortion, cracking or growth. The cast iron is sufficiently removed from high temperature concentration to avoid the faults of growth and distortion common to this metal when exposed to high temperatures for long periods. Heat is rapidly conducted through it and the temperatures are high enough to suit the purpose completely. The two metals, in the solid cast association described, are ideally suited to service requirements.

This application is a continuation of application Serial No. 69,578. What is claimed as new: s

l. Method of lmaking castings having defined areas diiering in analytical, physical and structural attributes,- which consists in pouring into a mold cavity a metal of predetermined analysis, and before it solidifles pouring in endwise relation a metal of different analysis, and preventing substantial interpenetration of the two metals by chilling one or the other poured metal at a point immediately adjacent the zoneY of fusion.

2. Method ofmaking heat accumulator units for stoves of the sealed type, which consists in forming as an integral casting a shape having def lined areas of different attributes by successively .of chrome cast iron, the metal of one of said sections being poured around a chill insert arranged closely adjacent the line of fusion whereby the mergence of the metals is substantially confined to the zone of fusion.,

4. Method of making solid cast heat accumulator units comprising chrome cast iron and cast iron in which said respective metals are limited to definite endwise sections of the casting, which comprises casting the sections separately in endwise arrangement while introducing a chill at the zone of fusion to vlimit penetration of the metal of one section into the metal of the other section.

5. Method of making solid cast heat accumulator units comprising cylinders of chrome cast iron and cast iron, respectively, having a substantially clearly dened line of demarcation, which consists in casting the shapes in the order stated under fusing' conditions, and preventing the cast iron from substantially penetrating the chrome cast iron by accelerating the rate of cooling of the chrome cast iron in the immediate area of the zone of fusion.

6. Method of' making solid cast heat accumulator units comprising cast bound cylinders of chrome cast iron and cast iron, respectively, having a substantially clearly defined line of demarcation, which consists in casting the shapes in the order statedunder fusion conditions, and preventing the cast iron from substantially penetrating the chrome cast iron by introducing a ring chill into the chrome cast iron at its point of mergence with the cast iron.

7. Method of making solid cast heat accumulator units comprising cast bound cylinders of chrome cast iron and cast iron, respectively, having a substantially clearly defined line of demarcation, which consists in` casting the shapes in the order stated under fusion conditions, and preventing lthe cast iron from substantially penetrating the chrome cast iron by introducing a ringchill into the chrome cast iron at its point of mergency with the cast iron, and chilling the remote end of the cast iron to reduce the amount of graphite precipitation.' 8. A heat accumulator unit comprising cylindrical shapes of chrome cast iron and cast iron, respectively, in cast bound arrangement, the chrome cast iron shape having a chill insert to linhibit substantial penetration by the cast iron,

and the cast iron section having a chilled area at its outer end to cause a reduction of graphite precipitation.

9. The method set forth in claim l in which some of the molten metal is run oil in the vicinity of the chilling area so asto remove impurities and to insure homogeneous union of the separate metals.

1o. Method se: forth in claim 1 in which the'.

to the zone of fusion and yet the metals are homogeneously united due to the substantial presence ot cast metal throughout the chill.

12. Method of making solid cast heat accumulator units comprising barrel shape units welded together in end to end relation and formed, respectively, 'of chrome cast iron and cast iron, which comprises substantially simultaneously casting the barrel sections in endwise arrangement, the rst metal being poured through and beyond the level of an open helical chillto limit penetration of the metal into the second poured metal, and adjusting said level to insure sound welding metal by flowing oil some of one or both metals at or about the zone of fusion.

y13. Method of making solid cast heat accumu-y lator units comprising end to end cast bound hollow cylinders of chrome cast iron and cast iron, respectively, having a substantially clearly deiln'ed line of demarcation, which consists in casting the shapes in end to end relation under fusion conditions and with provision for mutual washing of the eventual welding areas, and preventing the chrome cast iron from substantially penetrating the cast iron by introducing a ring chill in the form of an open coil into the chrome cast iron at an effective point below its merzence with the cast iron.

14. A heat accumulator unit comprising a barrel formed of hal; barrels joined end to end and composed, respectively, of chrome cast iron and cast iron, the chrome cast iron shape having aring chill insert comprising a ring coil to inhibit substantial penetration by the cast iron, and the cast iron shape having a chilledarea near its outer end to reduce the amount of graphite precipitation.

15. In the composite casting of structures which in service are exposed to high temperatures and so prone to separate, said structures comprising barrel shape members arranged end to en d and composed, respectively, of chrome cast iron and cast iron. the steps which comprise pouring the metals separately towards a common point of mergence, limiting inter-penetration of the metals in order to maintain their separate identities by chilling the metals at or about the zone of fusing by causing the cast iron without appreciable interruption of its iiow to traverse an open helical chill, and ilowing oft some of the cast iron at or about the zone of fusion so as to insure homogeneous union of the separate metals.

nsv

Images