US1655064A - Method of and apparatus for casting - Google Patents

Description

Jam 3, 192a.

" J. B. LADD 7 METHOD OF AND APPARATUS FOR CASTING Filed June 24 2 s Sheets-Sheet 1 UVVE/VTUI? JM 3- BY I ATTORNEY Jan. 3, 1928.

' J. B. LADD METHOD OF AND APPARATUS FOR CASTING 3 Sheets-Sheet 2 Filed June 24 1921 A 7 TORNE Y Jan. 3, 1928.

J. B. LADD METHOD OF AND APPARATUS FOR CASTING Filed June 24. 1921 3 Sheets-Sheet 3 INVENTO/i' doegwgw AUORNEY Patented Jan. 3 1928.

UNITED STATES PATENT OFFICE.

JAMES B. LADD, OF ARDMORE, PENNSYLVANIA,

ASSIGNOR TO UNITED STATES CAST IRON PIPE & FOUNDRY COMPANY, OF BURLINGTON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF AND APPARATUS FOR CASTING.

Application filed June 24, 192;. Serial No. 480,005.

My invention relates to the making of cast iron pipe by the centrifugal method in rotary metallic molds. As heretofore practiced the casting of iron pipe in cene trifugal metallic molds has resulted in a chill in the casting which has impaired its value and necessitated an expensive process of annealing to make the cast iron pipe coercially usable. I have discovered 310 that a cast iron pipe can be made devoid of chill in a centrifugal metallic mold by maintaining the centrifugal metallic mold at a high temperature, which temperature must of course be below the temperature at which cast iron solidifies but above the temperature at which the molecular structure known as a chill occurs during the solidifying and cooling of cast iron.

My invention consists essentially in so an regulating the temperature of a rotary centrifugal metallic pipe mold as to produce a cast iron pipe devoid of chill. Another feature of my invention consists in cooling the pipe while in the heated mold by forcing through it a cooling medium, preferably air under pressure.

Cooling the pipe from within while in a hot mold is of special importance because it causes shrinkage to occur first on the inside so of the pipe, and as the cooling extends out radially the outer layers of iron shrink onto the cooler inner layers and thereby materially strengthen the pipe against internal pressure on the principle used in the 85 construction of wire wound guns.

I am aware that all pipe made by the centrifugal process are cooled somewhat from the inside, but as such cooling is slight compared with the cooling from the mold side, m process differs radically from all others eretofore used in that I keep the mold at a high temperature to prevent cooling from without, and at the same time hasten the cooling from within by forcing a 4 cooling medium through the inside of the ipe. p Pipe cast as above described is distinguished from any pipe heretofore made due to the cooling being mainly from within and the outer layers devoid of chill and constitutes anot er feature of my invention.

The maintenance of the centrifugal mold at a high temperature brings about difiiculties in the construction of the mold supporting and rotating means which must be prevented from receiving by conduction from the mold too high a temperature. To prevent the overheating of the mold supports 1 provide heat insulating unions between them and the mold and this constitutes another feature of my invention.

In the drawing which illustrates a centrifugal metallic pipe mold and appliance suitable for carrying my invention into elfect.

Figure 1 is a plan View with the right hand housing partly cut away to show the roller supports.

Figure 2 a vertical central section on line 2 of Fig. l and partly on line H of Figure 3 is .a cross section on line 3-3 of Fig. 2.

Figure i is an end elevation of the right hand end of Figs. 1 and 2.

Figure 5 is a sectional detail showing a modification.

Figure 6 is an enlarged detail, and

Figure 7 a modification of the device shown in Fig. 6.

A and A. are the housings of the machine supporting bearin s B for the shafts G which support the bearing rollers C. D, D, are cap pieces for the housings elastically held in place by springs I) held on studs D as shown. These caps support bearings D for the shafts E of the upper bearing rolls E. F is a cylindrical casting having a flange F and a roller bearing ring F secured upon it which is supported on the rollers C, C, and E of the left hand housing. G is a somewhat similar cylinder having a flange G and bearin ring G su ported on the bearing rolls 0 the right hand housing. H is a drivin pulley secured to c linder G. I is a metallic mold having, as s own, a bell end I and terminal flanges I ahd I by which it is secured to flanges F and G of the rotatable cylinders F and G. J is a ring secured in the plain end of the mold to retain the molten metal. K is a cylinder insertable in the cylinder F and having its end fitting in the end of the bell of the mold and a projection K which serves as a core for the bell end of the pi e. Holes it are formed in it to register with to the desired temperature.

air space S. In the modification shown in Fig. 5 the cylinder 7.", is so constructed as to afford seats at k and 7e for cores k and is. L is the pouring trough. M an air pipe having a port m. M is a sleeve turning on pipe M and having a port m which opens into a nozzle M. N, N, are supports for a furnace chamber made up of a casing N, N preferably lined with fire brick. N N are vents in casing section N P is a gas pipe from whch burners P extend into the furnace chamber.

As shown in Figs. 2 and 6 the flange of the mold support, F or G, and the flanges of the mold shown at I or I are formed with projecting studs 6 g which abut against each other and through which pass the bolts Q. By this means a spaceS is left between the flanges of the supports and of the mold which acts as an insulation and prevents the heat of the mold from passing by conduction to the supports in too great degree. In Fig. 7 I have indicated that washers R of insulating material can be used to space the coupled flanges.

The metal mold must be maintained at a temperature which will permit the charge of molten iron to solidify and at which the iron will solidify without effecting the molecular change in the iron which produces what is known as chill. This involves the maintenance of a mold temperature which will vary somewhat with difl'erent composi tions of iron, but which for ordinary irons will be in the neighborhood of 1600 degrees Fahrenheit and should not be below 1200 degrees Fahrenheit.

The solidification and cooling of the casting' takes place partly by the conduction of heat from the casting through the walls of the mold but mainly by radiation and conduction from the inside of the casting, and it is highly advantageous to provide means for carrying away heat from the inside of the casting by forcing an energetic flow of a cooling medium, preferably air, through the hollow casting.

In view of the high temperature at which it is necessary to maintain the mold in my process it is obviously very desirable that the mold should be made of an alloy capable of being highly heated without softening, corroding or becoming deformed; such an alloy as that known as nichrome is well adapted for my urpose.

In operation t e mold I is secured to the rotatable cylinders F and G, as indicated,

and the cylinder K or k is inserted. Rotary motion is given to the mold as by the pulley H and the furnace N, N", is heated by gas, from burners P until the mold is raised Molten iron is then introduced as by arunner L and properly distributed in the mold by its centrifugal action, and an air blast is forced eaaoea through the mold and casting through the nozzle M When the casting has set and suiiiciently cooled the cylinder, K, is withdrawn and the pipe drawn from the mold through cylinder F.

The apparatus illustrated, with the exception of the air blast and heating and insulating devices, is of the general character used for centrifugal pipe casting and is shown simply as an apparatus Well adapted for practising my invention.

It is of course understood that the mold may be charged with molten iron by any suitable means, and accordingly my process is not limited to the use of a. short pouring runner such as is shown on the drawings, as I may introduce molten iron into the mold throughout its length with a rotary trough or with a long movable end pour runner or other means.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. The method of making cast iron pipe which consists in heating a metallic mold having the configuration of the outside of the pipe to be formed to a temperature below that at which cast iron solidifies and sufiiciently high to insure that the casting shall be devoid of chill, rotating the heated mold on its axis at a speed which will'centrifugally distribute the molten iron into the form of a pipe, charging molten iron into the heated rotating mold in quantity Suficient to form a plpe and maintaining the iron in the heated rotating mold until it solidifies in contact with the mold and contracts on cooling.

2. The method of making cast iron pipe which consists in rotating a hollow metallic mold on its axis, maintaining said mold at a temperature below that which cast iron solidifies and at 'a temperature sufficiently high to insure that the casting will be devoid of chill, chargin molten iron into said mold in quantity su cient to form a pipe, passing a cooling medium through the charged mold to cool the casting and maintaining the iron in the heated rotating mold until its solidifies.

3. The method of making cast iron pipe which consists in rotating a hollow metallic mold on its axis, maintaining said mold at a temperature below that at which cast iron solidifies and at a temperature sufliciently high to insure that the casting will be devoid of chill, charging molten iron into said mold in quantity suflicient to form a pipe, passing a cooling medium through the charged mold in such manner as to cool the casting rapidly from within and maintaining the iron in the heated rotating mold until it solidifies.

4. In apparatus for centrifugal castingcomprising a rotatable mold, supports for the mold and means for heating the mold,

emon the combination therewith of'heat insulating means for kee ing the heat of the hot me] from the mold sup rts.

5. In apparatus or casting pi e comprising rotatable mold supports an means for supporting the same, a centrifugal mold and means formaintaining the mold at a high temperature, the combination therewith of heat insulating unions between the mold supports and the mold whereby the .suppor'ts can be maintained at a materially I lower temperature than the mold.

6. In apparatus for casting pi compris ing rotatablemold supports an means for supporting the same, a eentrifu a1 mold and a furnace enclosing said mold can be maintained at a hi h temperature, the combination therewith 0 heat insulating unions between the mold supports and the mold whereby the supports can be maintained at a materially lower temperature than the mold.

JAMES B. LADD

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