US2689990A - Centrifugally cast product and method of making same - Google Patents

Centrifugally cast product and method of making same Download PDF

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Publication number
US2689990A
US2689990A US213745A US21374551A US2689990A US 2689990 A US2689990 A US 2689990A US 213745 A US213745 A US 213745A US 21374551 A US21374551 A US 21374551A US 2689990 A US2689990 A US 2689990A
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United States
Prior art keywords
mold
iron
cast
casting
molten
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Expired - Lifetime
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US213745A
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English (en)
Inventor
Martin L Samuels
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United States Pipe and Foundry Co LLC
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United States Pipe and Foundry Co LLC
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Priority to US213745A priority Critical patent/US2689990A/en
Priority to GB22193/51A priority patent/GB697271A/en
Priority to FR1051365D priority patent/FR1051365A/fr
Application granted granted Critical
Publication of US2689990A publication Critical patent/US2689990A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/02—Centrifugal casting; Casting by using centrifugal force of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force

Definitions

  • the present invention relates generally to centrifugal casting and pertains particularly to a novel method of centrifugallycasting chilled iron (white cast iron) tubular bodies, and to the improved castings obtained thereby.
  • chilled iron tubular products to which the invention relates will be referred to hereinafter as rolls since they are admirably suited for use as grinding or milling rolls and are widely used in industry for that purpose.
  • the lack of uniformity due to segregation of eutectic cementite may pass unnoticed when the roll is first placed in use, and may be discovered only after it has caused the roll to wear unevenly after considerable use.
  • the segregated cementite being considerably harder than the adjacent layers of metal which form the bulk of the roll, quickly manifests itself by dulling the corrugating tool, and by greatly resisting the passage of the tool, making the corrugating procedure more difiicult and time consuming.
  • centrifugally cast chilled iron roll characterized by a uniform distribution of its pearlite constituent in a matrix of cementite.
  • a further object is to provide chilled iron rolls of the character described above wherein the carbon constituent, calculated as total carbon, is distributed throughout the Wall thickness of the roll with greater uniformity than has been possible by prior art centrifugal casting methods.
  • An additional object is to provide castings having the foregoing properties and in which the primary crystals are disposed substantially perpendicular to the wall of the casting and extend throughout the thickness thereof.
  • a further object is to provide a centrifugal casting method capable of producing the foregoing cast products.
  • Fig. 1 is a full cross-Wall section, actual size, etched, of a chilled iron centrifugal casting manufactured according to the prior art
  • Fig. 2 is the same section shown in Fig. 1, but at 20 diameters magnification
  • Fig. 3 is a full cross-wall section, actual size, etched, of a chilled iron centrifugal casting made in accordance with the present casting method.
  • Fig. 4 is the same section shown in Fig. 3, but at 20 diameters magnification.
  • the remaining innermost layer of liquid metal by this time has attained the rotational speed of the mold and therefore freezing thereof takes place without any further breaking off of the dendrites growing inwardly from the previously frozen layer.
  • the result is that the centrifuging action outlined above may not now take place and the innermost layer of the casting is therefore substantially free from cementite segregation.
  • the mold speeds that I prefer to use in the practice of my invention are those which will impose a centrifugal force of 175 to 200 times gravity on the molten metal, measured at the outer wall surface of the tubular body being cast (1. e., the inner wall surface of the mold), although I have found that somewhat lower and considerably higher mold speeds may be used advantageously.
  • any higher mold speed may be used which is consistent with safe operation of the spinning apparatus.
  • the conventional basic formula for determining the centrifugal force on a particle moving in a circular path is:
  • F is the centrifugal force exerted by the rotating body, expressed in pounds
  • W is the weight of the rotating body in pounds
  • V is the velocity of the rotating body in linear feet per second
  • g isthe acceleration due to gravity, usually taken as 32.17 feet per second per second
  • r is the radius of the circular path of the body, in feet.
  • VFW VFW and that any new angular velocity V2 which will exert a force K times that of the mass of the body affected is related to V1 as follows:
  • the primary or tree-like crystals increase in size and number as the temperature falls to the solidus, or end of freezing, and transform upon cooling through the critical range into pearlite with the rejection of some free carbide.
  • These dendrites are also designated as the pro-eutectic phase
  • Examples 3 and 4 are only illustrative, and that these values may be varied to suit the conditions of a particular casting operation. In general, however, I prefer to use a pouring temperature for the cast iron of at least 2400 F., a mold temperature at pour of at least 200 F., and a pouring rate of at least 8 pounds of molten cast iron per second.
  • a portion of the eutectic austenite joins on to the primary dendrites and another portion separates as islands within the cementite, both portions transforming into pearlite upon cooling through the critiron carbide which bands are separated by a band very high in iron carbide (eutectic cementite) the latter being non-columnar in structure and therefore destroying the continuity of the columnar primary crystal structure of the dendritic bands across the Wall of the casting.
  • the :ands exhibiting low and high carbon content are not always exactly concentric with the outside circumference of the roll.
  • the finishing machine cut therefore, can be in a low carbon or soft zone in one place and in a high carbide band in another, so irregularities exist as regards surface luster, hardness (and therefore wear resistance) and machinability where fine longitudinal grooves or corrugations have to be cut in the roll.
  • chilled iron centrifugal castings made by the present casting method are characterized by a remarkably uniform distribution of the primary dendrites (pearlite) in the matrix of eutectic carbide material, throughout all of the dimensions of the castings. This structural uniformity is reflected by a very regular surface luster, uniform hardness (and therefore uniform wearing qualities), and much easier machinability.
  • a further characteristic of the present castings is that the primary dendrites, i. e. primary crystals, when viewed macrostructurally, are disposed radially of the casting, this macrostructure extending throughout the entire wall thickness thereof, producing the columnar structure visible in Fig. 3.
  • the primary dendrites i. e. primary crystals
  • the method of casting a white cast iron tubular body comprising rotating a cylindrical metal mold supported substantially horizontally for rotation about its longitudinal axis, at a speed which will impose a centrifugal force measured. at the inner wall surface of said mold of at least 125 times gravity on molten iron introduced into said mold, introducing into said rotating mold a charge of molten cast iron at such a rate that substantially said entire charge is introduced into said mold before any appreciable freezing of charge takes place, the charge of molten cast iron being of a quantity suificient to yield a tubular casting having a wall thickness of at least one-half inch as cast and of a composition which will freeze in said mold entirely as white iron, and maintaining said rotational speed of the mold throughout substantially the entire time that said molten iron is freezing therein.
  • composition of said cast iron falls within the following specification:
  • the method of casting a white cast iron tubular body comprising introducing into a rotating cylindrical metal mold supported substantially horizontally for rotation about its longitudinal axis a charge of molten cast iron suincient to yield a casting having a wall thickness of at least one-half inch, the temperature of said mold being greater than 200 F., the pouring temperature of said cast iron being at least 2400 F.,. the pouring rate of said cast iron being such that substantially said entire charge is intro-- cuted irrto said mold before any appreciable freezing of said charge takes place, and the composition of said cast iron falling within the following specification:
  • the rotational speed of said mold being such as to impose a centrifugal force of between and 200 times gravity on said molten iron, which force is measured at the inner wall surface of said mold, and maintaining said rotational speed throughout substantially the entire time that said molten iron is freezing.
  • the pearlite component is uniformly distributed in a matrix of cementite throughout the dimensions of the product, the variation in carbon content across the wall thickness of the product, calculated as total carbon, is no greater than about 15 points, and the primary crystals of said product, viewed niacrostructurally, are disposed substantially radially thereof, said macrostructure extending throughout the entire wall thickness of said product.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
US213745A 1951-03-03 1951-03-03 Centrifugally cast product and method of making same Expired - Lifetime US2689990A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US213745A US2689990A (en) 1951-03-03 1951-03-03 Centrifugally cast product and method of making same
GB22193/51A GB697271A (en) 1951-03-03 1951-09-21 Improvements in and connected with centrifugally casting tubular iron bodies
FR1051365D FR1051365A (fr) 1951-03-03 1951-10-22 Produit en fonte centrifugée et son procédé de fabrication

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US213745A US2689990A (en) 1951-03-03 1951-03-03 Centrifugally cast product and method of making same

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US2689990A true US2689990A (en) 1954-09-28

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US (1) US2689990A (fr)
FR (1) FR1051365A (fr)
GB (1) GB697271A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2731690A (en) * 1954-07-29 1956-01-24 American Cast Iron Pipe Co Method for the manufacture of centrifugally cast tubular metal articles

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1277543A (en) * 1918-03-23 1918-09-03 Frank D Carney Hollow ingot and method of making same.
US1707117A (en) * 1924-05-03 1929-03-26 Frank B Foster Method for making metal castings
US1882516A (en) * 1930-06-04 1932-10-11 Naugle & Townsend Inc Making blooms, slabs and billets
US2420298A (en) * 1942-12-01 1947-05-13 Durward E Breakefield Method of centrifugal casting

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1277543A (en) * 1918-03-23 1918-09-03 Frank D Carney Hollow ingot and method of making same.
US1707117A (en) * 1924-05-03 1929-03-26 Frank B Foster Method for making metal castings
US1882516A (en) * 1930-06-04 1932-10-11 Naugle & Townsend Inc Making blooms, slabs and billets
US2420298A (en) * 1942-12-01 1947-05-13 Durward E Breakefield Method of centrifugal casting

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2731690A (en) * 1954-07-29 1956-01-24 American Cast Iron Pipe Co Method for the manufacture of centrifugally cast tubular metal articles

Also Published As

Publication number Publication date
GB697271A (en) 1953-09-16
FR1051365A (fr) 1954-01-15

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