DE1758240A1 - Centrifugal casting process for the manufacture of assembled metal objects - Google Patents

Description

PATENT ANWXLTE DR. E. WIEGAND DIPL-ING. W. NIEAAANN DR. M. KÖHLER DIPL-ING. C. GERNHARDT 1 7 5 8 2 A MÖNCHEN HAMBURG TELEPHONE: 395314 2000 HAMBURG 50, 28 »** · ^ TELEGRAMS: KARPATENT KONIGSTRASSEZi

W. 13 656/68 12 / bottle

Kubota Iron & Machinery Works, Ltd, Osaka (Japan)

Centrifugal casting process for making assemblies Metal objects

According to the invention, highly viscous flux is used high temperature of a mass of metal forming an outer layer during centrifugal casting added to create and maintain a flux coating on the outer layer before it solidifies and prior to adding the molten metal mass which forms an inner layer, with the mold at rest is.

The invention relates to improvements in centrifugal casting for casting two or more Metal alloys into a single body, for example for a composite roller or roller. In particular the invention relates to a centrifugal casting

009882/0708

drive, in which a special flux composition is used to prevent the formation of an oxide film at the interface between the separately cast alloys to prevent.

A main purpose of the invention is therefore to eliminate casting defects, for example insufficient melt formation between the alloy layers, and change in thickness. one or more of the cast alloy layers according to the on one side of penetration or enforcement a metal alloy, whereby these two problems are common in the dragging of multilayer metal bodies, when conventional centrifugal casting processes and conventional fluxes are used will.

In cases where cast articles have mechanical properties should have different from the various metals forming the cast article, for example between the outside and inside layers, it is common to use two or more different metal alloys to cast a single casting, which is layered and has multiple layers, since casting only one metal alloy usually meets the requirements Cast article can not meet.

A composite drum or roller for metal rolling machines usually comprises an inner layer made of ductile cast iron of great toughness, which is a high stress cast iron is known, and an outer layer on which is made

003882/0708 BADORlGtNAL

a quenched or cast iron alloy is formed, which is characterized by high hardness, adamite, alloy grain, etc. is marked. Such rolls are made by casting processes in which the outer layer is formed by centrifugal casting techniques and in which the inner layer is formed by pouring a molten mass of tough metal onto the inside of the outer layer after the mold and layer are vertically erected and arranged. In order to prevent the formation of an oxide film on the inner surface of the outer layer during the solidification of this layer, it has been customary to cover this inner surface with a coating of flux, since the presence of the oxide film causes the fusion between the outer layer and The flux coating was obtained by spraying either a flux such as soda ash, lime, etc. on the inner surface of the outer layer after solidification while the mold is kept rotating, as in, for example Japanese patent 202,616, or by adding flux to a fce ^sGnin0 -'- ^zerier] metal mass, which forms the outer shield, when this is poured into the centrifuge! or :: *. <■ - ■ as it is in the Japanese godmother "dun _; 39 ObO ti) is described.

. Since Ic Flu3ci "'te material he ·, pursuant et if; .- * - :. V vrv -; weraer namely Na _{o CV:!;} Or Katrl: · -

Calcium fluoride (CaP ₂ ), salt (NaCi) and limestone (CaCO ₃ ) have a certain melting point and show low viscosity in the molten state, any of the aforementioned fluxes will flow on the inner surface of the outer metal layer after the metal mold has finished rotating downward and when it is level Form the flux, as shown in Fig. 2 of the drawing, forms a molten amount of flux F, by which amount of flux F part of the outer metal layer is kept in contact therewith at a relatively high temperature. If the inside of the outer metal layer is kept at a temperature just below its melting temperature, when the mold is erected for subsequent Gf% en of the inner metal layer, the molten amount of flux F flows down along the inner wall of the outer layer, as best shown in Fig 3 can be seen. When the molten metal forming the inner layer is then poured into the outer layer, which is kept at this relatively high temperature and in this state due to the flux concentration, the outer layer O is then thermally damaged at that surface part which is in contact with the molten amount of flux F is located. The result is the creation of a cast article which has a change in the thickness of the outer layer as shown in FIG. In contrast, if the inner surface of the outer layer is kept at a temperature that

009 882/07 0 8

BATH ORIGINAL

_ 5 -

is lower than the solidification temperature of the flux, The flux solidifies on the inner surface of the outer layer to the point where it is difficult for the flux will rise to the surface of the molten metal, which is then poured onto the inside of the outer layer to form the inner metal layer of the laminated body. This leads to the formation of a poor fusion bond between the outer and inner metal layers of the composite Casting. There is an endeavor in the known casting process that these disadvantages in particular at the ends of cylindrical cast counter-linden trees and it has been very difficult to obtain roll blanks free from such defects.

According to the invention, such casting defects are avoided by that a coating film of flux on the inner surface the outer layer is formed and a metal forming the inner layer is coated on the coating film.

Therefore, a primary purpose of the invention is to provide an improved casting method for producing Onea Metallschichtgußgegenstandes that no change in the layer thickness or insufficient SchasÄiinduni / zv, i · -o ^'f -> vr · the ÄuSenschicht and the inner ;; metal layer, ura ^ ar through the use of eir ^ r FIuSkI tcelcuää ^ r ^ üe «':. ^ u ::.;. , ws-chü the correct viscosity -ei ^ t, aie ausrsio ;; unö, ■:. ;; .. · βκ Iz- H. ^ bcr; dea Pii! r> alttelUb r ΐ '- ϊ, - ^: > to · - ■ * .dare r si: ίη _r : ·: ■;. ■:.! ' . · ■■.> ■ -': · .'.-. .:. Ι-Λ ^ ϋ., And ZV-. ;. ■ eel'vj--. ^^. '·';*>',; ■. ■.:' - ■ · - Ai '-.

ΒΛΟ

Another purpose of the invention is to provide such a casting process which can be conveniently carried out and in which the step of forming the inner layer by casting after forming the outer layer by centrifugal casting is carried out with relative ease owing to the fact that the viscosity of the according to the invention Flux composition used no loading. undergoes significant change over a wide range of operating temperatures.

Still another purpose of the invention is to provide an economical centrifugal casting process for the production of castings which does not adversely affect the properties of the metal layers forming the casting while allowing the use of a flux composition made up of compounds which are conventional fluxes form, and in which SiO ₂ and borax form the glass-forming constituents.

'Further purposes and advantages of the invention go from the following description, in which the - ^ finding for example, Pig. 1 is a sectional view of a hollow metal mold

with an outer layer of a roll blank formed by centrifugal casting and a uniform plus-medium coating according to the method of the invention. Fig. 2 is a sectional view of a hollow metal mold

2It is an outer layer formed by centrifugal casting

_BATH

ÄS 'rifiteni' Ί'Π

and a flux coating according to a known one Centrifugal casting process.

Fig. 3 is a sectional view of the metal mold and the through. Centrifugally cast formed article according to Pig. 2 after erecting the mold vertically.

4 is a sectional view of the outer cast layer vertical erection according to FIG. 3 and before pouring the material for the inner Metallahicht. Fig. 5 is a graph showing the relationship between the temperature and the viscosity of the flux composition according to the invention im • In contrast to conventional flux, which is used in known centrifugal casting processes.

In general, the centrifugal casting process or Schleuu.ergu: 3-vei drive according to the invention, characterized by the use of a flux composition containing 50 to 90 wt. a mixture of SiOp or silicon dioxide and borax, -jvA 10 ice 50 wt. ^> has at least one compound which is either a sodium compound, for example sodium carbonate, sodium fluoride, table salt, etc. or a calcium carbonate, such as limestone, potassium chloride, calcium fluoride '3>, lie iiußmitt el ^ composition is a molten iiia ^ se ve ;, which AuUensch l ■ -. -ht forming metal added that in > -. r: - M: -j.lfr ": gü3: = eij ■ which is to be added to nr ■"" _: , ^ oger (; o ;, ■ '..,. * ·. ;, j. r. ge üxa ^ eteri trowels rotated ^ ird, or _:. xr: l tu ·:.: .-: r;: vt-r vjr ^ eric :: "-.en gesci ^ iaolzenerj mass in the ic ^ alir,:. ■ -v ■; ,,

0098 S 2'O ⁷ Ce

to form an outer layer having an inner surface coated with a thin, uniform film of flux, in each case as a result of centrifugal casting. Instead, the flux can be sprayed onto the inside of the outer layer, which is produced by centrifugal casting, to create a thin, uniform film of flux on the inner surface of the outer layer Removal from the cleaning device erected vertically. A separate molten metal mass, which forms the inner metal layer, is then poured onto the inside of the outer layer, while the coating film is maintained at a temperature in the range of 800 to 1300 ° C, to form a unitary body, an inner and an outer Has metal layer which are fused together. Since the plasticizer composition used according to the "invention" is composed mainly of silicon dioxide (SiO2) and 3orax (Na, ^ C) of a glass-forming type, L? sodium compounds or vertim: ar; i: sr: j, which are added iar, a glazed: 53 * ϊ :, ": -; ί ; äs.bb <?. of the 'i'ernärsyatems form» namely 10 _r , - £. 0 ^ ~ /: Ά:. ■ ': .-)) with a melting point well below

uMt 2 of the aforementioned component © ,, , .1. se erLSugie glazed

Vlz '^ Bi'iiit, the- greater than

BATHROOM OBlGlNAL

the viscosity of the sodium or calcium compounds previously used where the degree of change in viscosity with decreasing temperature is extremely small »

With respect to the flux composition according to the invention, there is a tendency that the characteristics inherent in such an amorphous substance are unsatisfactory when the amount of borax is decreased below 50 fi , and furthermore, when the amount of borax is decreased, the viscosity at higher temperatures becomes too large is greater than 90 fo . The sodium and potassium compounds are used to control the flowability of a mixture composed of SiO2 and borax, i.e. to convert it from a mixture of a non-solidified type to a mixture of a solidified type and to lower its viscosity at higher temperatures. With proportions of these materials below 10 ⁰ Jo there is no noticeable result in lowering the viscosity, and when the proportion is increased above 50 7 ° , the properties inherent in amorphous substances and which are desired may not be present. These constituents should therefore be used in the stated proportion range in order to ensure that the flux composition has better properties than conventional fluxes.

From the graph of the pig. 5 are the excellent ones Properties of the plus composition according to the invention compared to conventional fluxes better known Process easily recognizable, the graph shows

009882''070S

■ - to -

the relationship between the temperature and the viscosity of the sodium or calcium compounds represented by the bold solid curve b, while the same relationship is represented by a curve a for the flux composition according to the invention consisting of 50 to 90% by weight of a mixture SiO ₂ and borax, and 10 to 50% by weight is composed of sodium carbonate. The hatched area represents the correct viscosity range ". A viscosity greater than a viscosity falling within this range causes poor melt bonding between the layers and the casting can be heat damaged if the viscosity is less than that indicated by the hatched area From Fig. 5 it can be clearly seen that curve a covers a very wide temperature range from 800 to 1300 ° C., in which it still falls into the hatched area, so that flux with an appropriate viscosity is created E ₁ is to be distinguished from a very narrow region R "for curve b. In other words, the amount of change in viscosity of the flux composition according to the invention is expressed in temperature compared to the amount of change usual yiu & ittel- ^! materials very little. Furthermore, from flg. 5 trstohtlloii »;

that the flux composition according to the invention has one ^; has a low solidification point and a higher viscosity even at a relatively low temperature,

009582/0708

■■■ '- 11 - -

while common flux has a high solidification point.

The way in which the flux composition - The outer metal layer can be applied according to the invention, can change, as is illustrated by three examples is indicated.

First, a molten metal mass, which forms the outer metal layer of the laminated cast body, and with which the. The flux composition is mixed, poured into the metal mold, which is then rotated at high speed. Since the flux composition carried by the molten mass has a specific gravity - which is less than the specific gravity of the metal ₉ / it moves to the inner surface of the outer metal layer due to the centrifugal force, which is 'generated' during the pulp éleisallform -M ', around a transfer film of the flux composition F on the outer metal layer O -su-srstages _o '

A second mode of operation comprises the true liagisSss of the flux amalgamation into the Ss ^ allfozTi. JaüOii ssoßsol glsiolazeitig with the Eingisßea the ^ "· -; r;:}: ί ^ ϊζ123: _ϊ.ζ ύ Ί?.?." / Eloae aie emxißere MetallsciiiciirS ii, X ( '3 _^: ^ eiir.islsi. .-sii ;: ΐ v'JV- ^ s ^^

um 'a He _s ? ec3i: s sii. ΐ7ηρ.1.ΐ Yi - a ^ lc ^ -ic \ ..- ii; "::: - '^': Hq & βέ first work ^ exs' ?: " Ab: "'aj; i ^ ::: l -: / u' ■ :

Third, Ιϊ-ιώε eil j fZ; 'iivriP.'Vcoi.saai ^. ^ rv ^ ij ^ ir ¹ : ·. · ^ - ^. - ,: -V ^ j; ^; »» 'area © der iluSansöiiieäl; > ::. ::; - ;; -. -: - fcl: ':.'. c. : -: /; ■ .- '■. ■ <■■ '"-.- J" ■ · - ■: .-: .-,:'-.> ■■■.

öer

BAD ORIGtNAL-

is to be obtained, the rotation of the metal mold M is stopped after solidification of the outer metal layer and the mold is then erected vertically to her for pouring a molten mass of metal which will make up the inner layer educates, prepares. When casting relatively small objects, the metal forming the inner layer is poured in, while the metal mold is kept rotating,

Since the flux composition according to the invention exhibits a high viscosity over a relatively wide temperature range, the flux composition does not flow down to form a molten amount of flux on the lower side of the outer layer, and a cut of the shape at this point, which increases the evenness of the flux coating shows, can easily be seen from a consideration of FIG. 1 in contrast to FIG. 2. This uniform flux layer is maintained even if the rotation of the metal mold is stopped, and the flux composition still does not flow downward as shown in Fig. 3 even if the metal mold M is erected vertically. Therefore, a coating of flux of approximately uniform thickness is formed over the entire inner surface of the outer metal layer. Before molten metal variables for forming a Innenachicht in the metal mold, which .trä the outer layer formed by centrifugal casting {1, eingei = e * can cie rotation of the metal mold angehcü th Vi ^ lems, and can s for a certain time until the pouring of

0; ■ 9 3 8 2/07 ■ ■.:

BATH ORIGINAL

Spread material for the inner layer. However, there is a wide range of acceptable temperatures, namely from 800 to 1300 ° C to maintain the correct viscosity of the If flux is present, there is no need to feed / flow the material forming the inner layer directly.

Since the flux composition, which is a cannot form crystalline or amorphous mass, has a low solidification point, gas bubbles are formed by the metal forming the outer layer, as it solidifies, are driven from locations or parts within the outer layer to the inner surface of the outer layer. These Gas bubbles rise to the inner surface of the coating film Flux composition after penetrating through the Coating film, and even if the gas bubbles on the inner surface of the outer layer are broken, there is gas emitted from the broken gas bubbles in the coating film in turn is enclosed to turn gas fields to form in the coating film, the inner surface of the metal layer is protected against oxidation and also protected by a Coating film of uniform thickness covering them, appropriately kept warm.

Since Sas Borax tends to form a eutectic mixture with metal oxides, it causes any bis-oxide, or grains of sand that can be carried to the inner surface of the outer layer, to rise to the surface of the molten metal mass, thus creating one

009882/0708

Casting leads to foreign material such as non-metallic Inclusions and free from casting defects, "for example insufficient fusion bond between the layers. The coating film made of flux helps keep the surfaces of the outer surfaces in contact with it evenly warm Metal layer without the formation of an oxide film. No flux composition is left between the inner layer and the outer layer P, i.e. at the interface between them, namely due to the fact that the flux composition for upper surface of the molten material forming the inner layer The amount of metal increases, as is the case when this amount of metal is poured into the metal mold, which is erected vertically according to FIG. 3 is, is the case.

Instead, when the inner layer is formed by centrifugal casting, the flux material moves to the inner surface of the inner layer, for example, when the metal mold is rotated about a horizontal axis. Thus, the inner metal layer of the cast metal laminate or composite body is in close contact with the outer layer and bonds therewith without the formation of any intermediate layer between the two metal layers over the entire interface between the layers. In this way, a tin casting is produced without the usual casting defects, for example inadequate fusion between the metal layers or unevenness of the wall

009882/0708

- ■ 15 -

Thickness of the outer layer according to local maintenance a of heat, as it is "generated in known processes where the flux tends to be in the position shown in fig. 2 depicted way to concentrate »The flux composition according to the invention consists mainly of cheap material, for example from. Silicate and Borax »Furthermore, the silicon and the boron, which cause the damage Flux does not form the casting if it should diffuse into the casting metal, and this also applies to I. Sodium and calcium applies. A particular example of a cast product using the method according to FIG Invention is explained below

example

In order to create a composite roller for use in a rolling mill, with a diameter of 0.695 m and a length of 2.184 m, cast iron with 3.4> carbon, 0.8 f > silicon, 0.6 fi manganese, 4.3 > nickel., 1.7 ⁰ A chromium, 0.45 * molybdenum and the remainder iron at 1380 ° G cast in a metal mold for centrifugal casting, the mold being rotated on rollers that are driven around a horizontal axis were to form an outer metal layer, and at the same time 45 kg of a flux composition consisting of 50 ° / o siop, 30 fa borax and 20 ~ / o sodium carbonate the Gußeiesn was added. The metal forra was kept rotating? until the metal forming the outer layer solidified ^

00 9e B -VZ-T) -VOIi- -

BADORiGiNAL

after which the mold was erected vertically, after which heavy-duty cast iron of 1390 ° C was poured to form the inner layer. There were 24 compound ones Rolls made by this process and there were "no defects such as insufficient melt formation between the

outer and inner layers, or changes in the wall thickness of the outer layer.

The same procedure was repeated with the exception that sodium carbonate alone was used as the flux, in which case 67 composite rolls were produced, of which 39 rolls exhibited the aforementioned defects.

00988 2/0708

Claims (1)

Claims 1. Centrifugal casting process for making composite Metal body in which a molten metal mass forming an outer layer is brought into a metal mold, the metal mold is rotated to "cause the metal mass in contact with the mold surface "moves and moves solidified, a flux for coating the inner surface of the outer metal layer is added and a separate one molten metal mass is added to the mold to produce a unitary cast metal body in which the ■ The outer layer and the inner layer are melt-bonded to one another, characterized in that a highly viscous3 flux is added and kept at a temperature in the range of 800 to 1500 ° C. 2 * The method of claim 1, characterized in that a Flüßmittelzusainmensetzung from 50 to 90 wt. $ Of a composite of silicon dioxide and mixtures of borax, and 10 to 50 wt. ■ 'f> is at least one sodium or calcium compound used » 3e method according to claim 1, characterized in that a flux composition is used which is 50 to 90 Gewo ^ o one composed of silicon dioxide and borax Mixtures, and 10 to 50 wt. 9 & sodium carbonate, sodium fluoride, Contains sodium chloride, limestone, calcium chloride, or calcium fluoride. 009882/0708 4. The method according to any one of claims 1 to 3, characterized in that that the flux is added to the mold by applying it to the inner surface of the outer metal layer the formation of which is sprayed on by centrifugal casting and solidification. 5. The method according to any one of claims 1 to 3, characterized in, that the flux simultaneously with the supply of the molten metal mass forming the outer layer as separate mass is added to the mold. 6. The method according to any one of claims 1 to 3, characterized in that the flux composition is supplied to the mold as a mixture with the molten metal mass forming the outer layer _o 7. Flux composition for use in a Centrifugal casting process for casting assembled metal objects from iron or the like, characterized in that that the flux composition is 50 to 90% by weight of a mixture composed of silicate and borax, and 10 to 50% by weight sodium carbonate, sodium chloride, sodium fluoride, Contains limestone, calcium fluoride, or calcium chloride. 00 9 882/0708 Blank page