US 2245994 A
Description (OCR text may contain errors)
June 17, 1941-. H, E, McwANE CASTING APPARATUS AND METHOD Filed Jan. 5. 1958 NAI Patented June y17, 1941 UNITED STATES PATENT OFFICE 2,245,994 CASTING APPARATUS AND ME'rnon Henry E. McWane, Lynchburg, Va. Application January 5, 1938, Serial No. 183,548 i 7 Claims.
My invention relates to ,casting processes, and in particular it relates to castingof metal articles wherein the molten metal is at a high tem -perature when poured into the mold In casting objects in metal molds, where the molten material is at high temperature, fluid metal such as, for instance, is the case in centrifugal casting of pipe, vthe cast objects are often chilled. This chilling of .the surface of the cast articles causes them to be uneven in their characteristics. This is highly undesirable in many cases, such, for example, asin the casting of cast iron pipe. Since articles chilled at certain spots of the surface are of uneven strength, it is difcult to determine the size and weight of any particular article to withstand a certain givenv usage. i
For instance, suppose a cast iron pipe has upon it sections of chilled surface. It is -then impossible to tell what metal thickness for a given size of pipe should be used for any given operating conditions, since the pipe is not uniform in its characteristics.
. A present-day method which manufactures pipe, and which is in large usage today, is the centrifugal method of casting. Under this present method, a rotary mold has deposited on its inner surface molten cast iron. The mold is usually of steel and is rotated at high speed. The
fluid cast iron is deposited evenly on the interior surface of the mold. When the pipe cools, it is extracted from the mold. At present probfably the most eiiicient centrifugal casting is the process in which a powder, that is, a mixture of ferro-silicon and finely divided sand and air,
is deposited on the interior surface of the rotating mold just prior to the deposition of the molten metal on such surface. It is practically impossible to prevent an uneven deposition of the ferro-silicon, divided silica sand and air, and this results, in many instances, in serious chilling of certain surface areas of 'thecentrifugally cast pipe. The reason for this is that the mixture is supposed to have an insulating eect to insulate the mold from theA molten metal and retard .the cooling, thus eliminating the `chill. Where the mixture is unevenly deposited, there may be insuilicient insulation at any particular point and this caus the chill.
Thepresent method,which is. the subject matter of this invention, contemplates heating the mold prior to the contact of the mold with the molten metal. In centrifugal casting of pipe, it
is desirable to heat the interior surface o; the revolving mold a short time prior to the deposition of the molten metal on this interiorv surface. By my method, I can eliminate the necessity for the insulating layer between the pipe and the interior surface of the mold. In general, I may use burners having a high temperature flame that plays directly on the interior of the revolving mold just prior to the initial contact of 4the molten metal with the molds interior surface. The type of dame, the direction in which it is directed, the number of heat units transferred to the interior surface of the mold in a given time, are all factors which must be determined empirically in -any given opera-tion. In general, I mount the burners on some portion of the spout, or the trough, which carries the molten metal to the'interior of the mold, though, obviously, any other means of producing the desired effect may be employed, such as. for instance, having a separate carrying mechanism for the burners. I
In my present invention, without limiting myself to any particular apparatus further than is called for by the appended claims, I have in mind that one of the objects of the invention is to prevent chilling of the surface of the cast articles. Another object of the invention is to use cast iron mixtures of varying composition. Heretofore, where using the process of centrifugal casting inV a metal mold for making cast iron pipe, it has 'been necessary to employ a mixture of cast iron having a high total carbon content to maintain a high :fluidity and also ,to prevent chill. The higher carbon content iron does not chill as readily as the lower carbon content. By my present method, I can obtain a desirable product with a, much lower total carbon content than has heretofore been the practice in this art. A product of substantially lower total carbon content than has been, heretofore,
` other desirable qualities. This minimizes cracking of the pipe under water hammer and from external forces.
To insure an adequate comprehension of my invention, there is shown in the accompanying drawing, one specific embodiment, but it will.
A'of course, beappreciated that my invention is capable of other embodiments and modincations.
In the drawing, in which similar numerals 1ndicaie the same part,
Figure 1 is a view in side elevation showing my manner of heating a rotary mold prior to the contact of thev molten material with the mold.
Figure 2 is a view taken along line'2-2 of Figure y1 looking in the direction of the arrows.
'Figure 3 is a fragmental sectional view through the mold showing .the manner in which the mold is heated prior to the contact of the metal with the mold.
Referring to the drawing and more particularly to Figures 1 and 2, there is shown a carriage I mounted-on flanged rollers 2. The rolle-rs 2 are adapted to travel on tracks 3. A suitable operating rod 3' attached to the carriage is adapted to impart reciprocating movement to the carriage from a source of power (not shown). A closure or hood l is removably amxed to the carriage I. Supported within the interior of the carriage I on ears 5 are a plurality of rollers E. A rotary mold depicted 1 is supported by the rollers 6. While I have shown the use of four rollers supporting the mold, it is, of course, obvious that a greater number can be used or some equivalent mechanism can be employed in lieu of that shown., As shown in Figure 3, the mold 1 is provided at one end with the usualbell-shaped portion 8, and a-core 8 inserted therein.
In order to impart rotary movement to the mold 1, there is provided an electric motor I which is suitably mounted on the top of the carriage I as shown in Figure l. A drive connection II is adapted to impart movement to a gearl I2 provided on the outer peripheryl of the bell-shaped portion 8 of the mold 1. Of course, any other type of power transmission device may be used.
Suitably secured to a lsupport I3 is a pouring trough Il having a spout I which is adapted to extend into the interior of the mold 1. vAs best shown in Figure 1` the trough I4 is provided is moved to such a position that the molten material, which I have designated 23, will first vfill up the bell end of the mold 1- The carriage then moves to the left (in Figure 1) at the required rate of speed and the molten material is fed into the interior of the revolving mold` It will be readily apparent that by the use of this process it will enable a cast iron pipe to be made of a much lower total carbon content than has heretofore been possible. Moreover, it will prevent the too rapid chilling of the surface of the finished cast product. Lastly, it will eliminate the use of the insulating material between the pipe and the interior surface of the mold.
While I have shown and describedthe preferred embodiment of my inventive concept, I wish it to be understood that I do not conne myself to the precise details herein set forth by way of illustration, as it is apparent that many changes and variations may be made therein by those skilled in the art without departing from the spirit of the invention or exceeding the with a guideway I5' for directing the molten material poured from a ladle I6 into the trough.
As heretofore pointed out, an essential feature nf the present invention is to heat the mold prior to the contact of the mold with the molten material. By thus heating the interior of the mold. the necessity of providing an insulatingy layer between the pipe and the interior surface nf the mold can be eliminated. Moreover, it will prevent too rapid chilling of the surface of the cast articles. As shown in Figure 3, a gas burner I1 which is adapted to give an intense flame is secured to the side of the trough adjacent the spout end so thatthe flame will play directly on the interior of the mold prior to the initial contact of molten material with the molds interior surface. In addition. a secondi burner I8 to give a plurality of brush flames is affixed to the bottom nf the trough immediately in rear of the burner I1.
Pipes I 9 connect the burner I1 with a suitable source nf combustion materials (not shown) and valves 2|) are provided for regulating the-amount nf combustion materials fed to the burner.
y Similarly. pipes 2| are connected with the burner II! and regulating valves 22 are interposed in the-pine line, to control the volume of combustion material fed to the burner.
'Ihe operation oi my invention is believed readily apparent. but it mightbe well to summarize briefly the steps of the process. As is well known. whenpipe is cast, it is usual to pour the bell end ofthe pipe rst. Therefore, the carriage I scope of the appended claims.
1. A method of centrifugal casting of pipe comprising discharging molten metal from a spout into the interior of a revolving mold While causing relative longitudinal movement between the spout and the mold so that a layer of metal is deposited on the interior surface of the mold to form a pipeand selectively heating the interior surface of the mold in front of the point of deposition of molten metal to a suiciently high temperature so that there is substantial elimination of chill in the casting.
2. A method of centrifugal casting of pipe comprising discharging molten metal from a spout into the interior of a revolving mold while causing relative longitudinal movement between the spout and the mold so that a layer of metal is deposited on the interior surface of the mold to form a pipe and selectively directing a ame against the interior surface of the mold in front of the deposition of the metal to raise the temperature suflciently so that there is substantial elimination of chill in the casting.
3. An apparatus for centrifugal casting of pipe comprising a revolving mold; a trough; a spout on the trough; a source of molten metal for the trough; means to cause relative longitudinal movement of the spout and the mold; and means maintaining a xed position with respect to the spout to selectively heat the interior walls of the.
mold in front of the deposition of the metal.
4. An apparatus for centrifugal casting of pipe comprising a revolving mold; a trough; a spout on the trough; a source of molten metal for the trough; means to cause relative longitudinal movement of the spout and the mold; andY a burner maintaining a fixed position with respect to the spout and selectively directing a flame against the interior walls of the mold in front of the deposition of the metal to raise its temperature prior to its contact with the molten metal. y Y
5. An apparatus for centrifugal casting ot pipe.
comprising a revolving mold; a trough; a spout on the trough; a source of molten metal for the trough and a plurality of burners occupying a relatively iixed position with respect to the spout and selectively directing a series of flames against the'interiorwalis of the mold in front of the deposition of the metal to raise its temperature prior to its contact with the molten metal.
6. A method of centrifugal casting, comprising rotating a mold, depositing a stream oi molten metal in the mold while advancing the point of deposition of the molten metal in the mold axially of the xnold,v and heating a small areaoi the inner surface of the mold immediately in ad# 15 Vance of the point of deposition so that the metal is deposited in a heated portion of the mold.
'1. A method of centrifugal casting, comprising rotating a mold, depositing a stream oi molten metal in the mold from the spout of a pouring trough while eii'ecting relative axial displacement between the pouring trough and the mold, and simultaneously eii'ecting relative axial displacement between a heating element and the mold with the heating element slightly in advance of the spout of the pouring 'trough to.
HENRY E. MCWANE.
CERTIFICATE 0E CORRECTION. patent No. 2,215,991 June I7, 19m.
.HENRY E. ncwANE.
It is hereby certified that` error appears in the printed specification of the above numbered; patent requiring correction as follows: Page 2, second Column, line 514, rc1aim2, for the words "raise the" read raise its; and that the said Letters Patent should be read with rthis correction therein that the same Inay conform to the record of the case in the Patent Office.
Signed and sealed this 2nd day of September, A. D. l9l|.l.
Henry Van Arsdale," (Seal) Acting Commissioner of Patents.