Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
  • B22D27/06—Heating the top discard of ingots

Definitions

• the exothermic compositions used as anti-piping compounds are generally of an aluminothermic composition i.e. containing finely divided aluminium and oxidising agent therefore. It is possible to use aluminium in relatively pure elemental form, as powders, turnings, sawings or the like but since it is desirable to keep the cost of the antipiping compound as low as possible it is convenient to use the commercial material known as ball mill dust. This is the ground product from slags obtained in the metallurgy of aluminium and usually contains alumina, flux residues and the like and aproportion of aluminium metal. The proportion of aluminium may vary Widely depending on the source of the ball mill dust but is generally 10 to 30% by weight.
• a fluoride e.g. an alkali metal or alkaline earth metal fluoride, or aluminium fluoride
• a mixed fluoride salt e.g. cryolite
• a fluoro complex salt such as a titano, boro or silico fluoride
• an anti-piping composition in powder or granular form which comprises aluminium and oxidising agent therefor together with an organic additive which at the temperature of the molten metal generates flame.
• organic materials comprising high proportions of carbon hydrogen and oxygen are very suitable for the purpose and many cellulosic materials are of value, for example, paper pulp, wood pulp and shredded paper. Materials such as wood flour and the like are particularly suitable.
• the material should preferably have a low bulk densitypreferably 0.2-0.4 gm./cc.-and a low moisture content.
• wood flour and sawdust preferably from hard wood and of particle size passing a 10 B88 mesh but without a substantial quantity passing a E88 mesh
• ground cobs or cob flour grain hulls and nut shells
• polystyrene and similar plastics chips cereal flours
• organic gums such as sulphite lye and gum arabic being usable but not preferred.
• a particularly preferred materials is 20+ 100 E58 mesh cob flour.
• a proportion of a humectant such as glycol or glycerol in a proportion of 1-20%, preferably 5-15% by weight of the composition to aid in reducing dust from the material.
• a humectant such as glycol or glycerol
• the anti-piping compositions according to this invention may contain a flame retardant which serves to spread the action of the anti-piping compound over a period of time rather than allowing it to proceed violently for only a short period of time.
• a flame retardant which serves to spread the action of the anti-piping compound over a period of time rather than allowing it to proceed violently for only a short period of time.
• Suitable materials for this purpose are silica flour and sodium chloride.
• a granular anti-piping composition for application to the surface of molten metal during casting thereof, the composition consisting essentially of aluminum and an oxidizing agent therefor and wherein the composition generates fumes upon its ignition after application to the surface of the molten metal, the improvement comprising including in the composition 1 -20% by weight of an organic additive, said organic additive being capable of generating a flame at the temperature of the molten metal and being present in an amount sufficient to consume the fumes produced by the composition.
• An anti-piping composition according to claim 1 which includes a humectant in an amount of 1-20 by weight of the composition.
• An anti-piping composition according to claim 1 which contains a proportion of a flame retardant.
• a method of casting molten metal comprising pouring said metal into a mold and applying to the surface of said molten metal during solidification in the mold a granular exothermic anti-piping composition containing aluminum and an oxidizing agent therefor, whereby application of the composition to the molten metal generates fumes, the improvement comprising applying to the surface of said molten metal with said anti-piping composition an organic additive which generates a flame at the temperature of said molten metal the additive being applied in an amount sufiicient to substantially consume the generated fumes.
• An anti-piping composition according to claim 1 wherein the organic additive is a member selected from the group consisting of paper pulp, shredded paper, wood flour, sawdust and cob flour.
• the organic additive is a member selected from the group consisting of paper pulp, shredded paper, wood flour, sawdust and cob flour.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Mold Materials And Core Materials (AREA)
• Paper (AREA)
• Fireproofing Substances (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10477325

Family Applications (1)

Country Status (4)

Cited By (3)

Families Citing this family (3)

• 1968
  • 1968-12-11 JP JP43090294A patent/JPS5220931B1/ja active Pending
  • 1968-12-13 FR FR1595059D patent/FR1595059A/fr not_active Expired
  • 1968-12-13 DE DE19681814637 patent/DE1814637A1/de active Pending
• 1971
  • 1971-03-01 US US00119943A patent/US3728102A/en not_active Expired - Lifetime

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