US3694194A - Method for the manufacture of centrifugal castings - Google Patents

Method for the manufacture of centrifugal castings Download PDF

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Publication number
US3694194A
US3694194A US857815A US3694194DA US3694194A US 3694194 A US3694194 A US 3694194A US 857815 A US857815 A US 857815A US 3694194D A US3694194D A US 3694194DA US 3694194 A US3694194 A US 3694194A
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United States
Prior art keywords
graphite
centrifugal
present
manufacture
castings
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Expired - Lifetime
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US857815A
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English (en)
Inventor
Milorad Mirjanic
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Daimler Benz AG
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Daimler Benz AG
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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

Definitions

  • the present invention relates to a method for the manufacture of centrifugal castings, especially of cylinder liners made from cast-iron having a high carbon content.
  • the carbon present in the structure separates out or precipitates, for the most part, in the form of spheroidal graphite which is not particularly favorable for the improvement of the emergency running characteristics because it is not securely connected with and bound in the surrounding structure but, instead, during operation, is readily detachable for the most part by breaking or flaking out.
  • the present invention is predicated on the aim to avoid the aforementioned shortcomings and to enable by a special method of the aforementioned type, the manufacture of cast iron saturated with graphite.
  • the present invention essentially consists in that the melt possesses a carbon content of over 4 percent by weight and the casting takes place at increased temperature of the melt and/or increased centrifugal velocity.
  • the mechanical casting conditions are so changed by the method in accordance with the present invention that it becomes possible to enrich and to supersaturate the cast iron with graphite to a farreachingly greater extent than heretofore possible.
  • the surprising advantage results in connection therewith that the graphite is present in the structure in lamellar form and, as a result thereof, is connected with or bound to the same particularly securely.
  • conventional alloy elements may be admixed to the melt which are so selected that the melt solidifies pearlitically and the graphite formation is enhanced in the structure.
  • a reduction of the silicon components and a reduction of the manganese components favor the graphite formation.
  • a special distribution of the graphite is also achieved by the change of the mechanical or physical casting conditions according to the present invention in that the interior wall is enriched more strongly with graphite than the external wall.
  • This is advantageous in particular for hearing sockets and cylinder liners since the the bearing surfaces thereof are located at the inner Walls enriched with high graphite content in lamellar form.
  • the cause for this distribution is apparently both the smaller viscosity of the melt conditioned by the higher temperature as also the larger centrifugal force which, each by itself or even more effectively, both together, effect that during the manufacture of centrifugal castings, the more heavy iron particles always migrate more strongly toward the outside.
  • the normal temperature of the melt as used at present for centrifugal castings of the type described above amounts to about 1550 Celsius.
  • the method is to be carried out at a temperature above this conventional temperature, preferably at a temperature of 1650- *-30 Celsius.
  • Centrifugal velocities are normally expressed in r.p.m.s (number of rotations per minute), depending on the diameter of the part to be made, e.g of a cylinder to be cast.
  • a rotational speed for the mold of such cylinder of about 1300 r.p.m. is standard at present.
  • the present invention contemplates a rotational speed of the mold in excess thereof, and more particularly within a range from about above 1300-4000 r.p.m.
  • the present invention prefers a rotational speed of about 14004650 r.p.m.
  • Carbon content 4.5 to 5.0%. Combined carbon 0.7 to 0.9%.
  • Vickers Hardness HV 0.05 in kg./mm. A hardness range between about 250-350 kg./mm.
  • Tensile strength A tensile strength 18 kg./mm. notwithstanding the desired high carbon content, realized by the admixture of approximate amounts of suitable alloy components, such as Cu and Ni in the proportions indicated above though the admixture of molybdenum in amounts of about 0.7- 1% and of other alloying elements with similar properties is also feasible. Obviously, the amounts of alloying components may vary substantially, as known to those skilled in the art, depending on the tensile strength in the centrifugally cast part which one seeks.
  • Lamellar pearlite very little phosphide deutecticurn.
  • the method according to the present invention of centrifugally casting parts of the type described above takes place in a conventional manner except for the increase in rotational speed and/or temperature as indicated above.
  • PEG. 1 is a photomicrograph (100:1 magnification) of the inner side of a first specimen of a non-alloyed cylinder liner made in accordance with the present invention
  • FIG. 2 is a photomicrograph (200:1 magmfication) of the specimen shown in FIG. 1;
  • FIG. 3 is a photomicrograph (100:1 magnification) of the inner side of a second specimen of an alloyed cyhnder liner made in accordance with the present invention.
  • FIG. 4 is a photomicrograph (200:1 magnification) of the specimen shown in FIG. 3.
  • a method for producing a centrifugal casting of castiron having a pearlitic matrix in which more than 4 percent by weight of carbon is present predominantly in lamellar form as graphite which comprises forming a castiron melt with a carbon content of over 4 percent by weight, admixing conventional alloying elements with said melt to be cast so that a melt solidifies pearlitically with enhanced graphite formation and with increased tensile strength, and centrifugally casting the melt under such casting conditions that at least the temperature of the melt is increased to be in the range of about 1620 C. to 1680 C. or the centrifugal velocity is increased to be in the range of about 1300 to 4000 revolutions per minute for a casting having an outer diameter up to 100 mm.
  • a method according to claim 2 characterized in that the temperature of the melt and the centrifugal velocity are so selected that the resultant cast structure has an inner wall enriched more strongly with graphite than the outer wall.
  • a method according to claim 2 characterized in that conventional alloying elements for the increase of the tensile strength are admixed to the cast iron.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
US857815A 1968-09-14 1969-09-15 Method for the manufacture of centrifugal castings Expired - Lifetime US3694194A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1783002 1968-09-14

Publications (1)

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US3694194A true US3694194A (en) 1972-09-26

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US857815A Expired - Lifetime US3694194A (en) 1968-09-14 1969-09-15 Method for the manufacture of centrifugal castings

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US (1) US3694194A (enrdf_load_stackoverflow)
FR (1) FR2018110A1 (enrdf_load_stackoverflow)
GB (1) GB1252040A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4025366A (en) * 1973-01-17 1977-05-24 Audi Nsu Auto Union Aktiengesellschaft Method of making rotary piston engine cast iron interior seals by quench hardening

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4025366A (en) * 1973-01-17 1977-05-24 Audi Nsu Auto Union Aktiengesellschaft Method of making rotary piston engine cast iron interior seals by quench hardening

Also Published As

Publication number Publication date
GB1252040A (enrdf_load_stackoverflow) 1971-11-03
FR2018110A1 (enrdf_load_stackoverflow) 1970-05-29

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