Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
  • B22C5/08—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by sprinkling, cooling, or drying

Definitions

• a still further objective of this invention is to provide a foundry sand handling system wherein the composition of the foundry sand can be easily controlled and the compositional variations are minimized.
• the amount of sand used to form a mold is usually expressed as a function of the amount of metal to be poured into it. This relationship is called the sand to metal ratio.
• sufiicient sand can be used for the mold to give a sand to metal ratio of from 3 to 1 to 20 to 1. While these ratios are frequently used, others are oftentimes used too.
• a common ratio used is a ratio of about 6 to 1. That is, a mold is formed which consists of 6 pounds of sand for each pound of metal to be cast.
• Foundry sand is, of course, not sand alone but contains additional constituents such as clays, carbons and/or other additives. Carbons in common use are, powdered coal, coal tar, pitch, asphalt, graphite and coke. Other additives can be added such as celluloses, cereal binders, etc. After one or more molding operations, new sand, clays and carbons can be added to the used sand to replace the portion of the original sand which has been made unusable. The following is a typical table which shows the amount of additives which usually must be added after the batch of sand has been used. This table is for ferrous metals other than steel. Other data for nonferrous metals, steel and ductile metals is known to those in the foundry industry.
• my invention provides a novel method of cooling foundry sand While at the same time it provides a method for controlling the composition of the foundry sand and for minimizing variations in composition.
• the amount of sand which must be added after shakeout in order to obtain a mixture of used and unused sand at a particular temperature is, of course, dependent upon the temperature of and the amounts of the used and unused sands. I have found that the approximate amount of unused sand which must be added can be calculated in the following way.
• An approximate estimation of the temperature of the sand at shakeout can be made if it is assumed that all the heat evolved from the hot metal is transferred to the sand.
• the temperature of the metal in an average pouring for iron is about 2600 F.
• the following table shows the heat evolved at the indicated shakeout temperature when the pouring temperature is 2600 F.
• the pouring temperature of the metal was 2600 F.
• the above temperatures can be plotted so that intermediate temperatures can be determined quickly.
• the above calculated sand temperatures assume that there is no moisture in the sand. However, in practice there is usually between 3 to 5% of water in the sand. The evaporation of this moisture will cool the sand still further. For example, at a 10 to 1 sand to metal ratio the sand will be cooled about 53 for each 1% of moisture evaporated. In most foundries the shakeout temperature is between 1000 F. and 1300 F. Therefore, in order to have sand at not more than 120 F. as it goes into the muller, the sand to metal ratio at this point must be between 10 to 1 and 20 to l. A 10 to 1 mixture will provide this temperature because about 3% of moisture has been evaporated.
• the amount of sand actually used to form the mold can be any ratio but common values are a sand to metal ratio of 4 to l to about 6 to 1.
• the muller used at the foundry was a continuous muller, that is, a continuous flow of sand was introduced into the muller and a continuous flow of mulled sand was discharged from the muller.
• the approximate composition of sand used was 89% silica, 6% clay, 5.3% carbons and 4% water.
• Periodic additions of clays, carbons and new sand, calculated according to the figures shown in Table I were made to the sand at the muller during the casting cycle. A large amount of sand was prepared. However, the molds were made on a 4 to 1 sand to metal ratio.
• the metal cast was a malleable iron having an approximate composition of 3.5% total carbon and 0.6% Si.
• the sand which was not used to form the molds was conveyed to a storage tank. After the metal was cast, the casings and molds were conveyed to a shakeout station and the molds broken. Immediately after the castings were separated from the broken molds at the shakeout station, about 16 parts of cool sand at ambient temperature from the storage tank were added to the hot used sand. The temperature of the used sand prior to the addition of the unused sand was over 350 F. By the time the mixture of hot used sand and cool unused sand had been transported by a conventional conveyor to a second storage bin, a distance of approximately 200 feet, the temperature of the batch was approximately 100 F. After this, the sand was conveyed to the muller.
• the temperature of the sand was approximately 90 F. No additional cooling of the sand was provided. It was then conveyed to the first storage tank. After using this process for several weeks, it was apparent that the quality of the molds and of the finished castings was greatly improved over the process previously practiced which included conventional sand cooling apparatus. Moreover, it was found that it was much easier to control the composition of the sand and there was much less variation in the composition. Additionally it was found that the sand was much easier to handle because its flowability was improved. Another unexpected result was that air pollution was drastically reduced. It is believed that expensive air cleaning equipment will also be eliminated by using my process.
• a foundry process comprising preparing a batch of foundry sand having a weight of at least ten times the weight of the metal to be cast,
• molds from a minor portion of said batch of sand, said molds each having a weight of from 3 to 6 times the weight of the material to be cast,
• a foundry process which comprises mulling used sand to provide a quantity of sand of at least as great as times the weight of the metal to be cast, said used sand derived from a later step in the process,
• molds from a minor portion of themulled mixture, said molds each having a weight of at least 3 times the weight of the material to be cast,

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mold Materials And Core Materials (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24869641

Family Applications (1)

Country Status (8)

Cited By (3)

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Citations (2)

• 1968
  • 1968-03-19 US US714339A patent/US3461941A/en not_active Expired - Lifetime
• 1969
  • 1969-03-13 GB GB1266606D patent/GB1266606A/en not_active Expired
  • 1969-03-14 DE DE1913092A patent/DE1913092C3/de not_active Expired
  • 1969-03-18 CH CH407569A patent/CH493290A/de not_active IP Right Cessation
  • 1969-03-19 NL NL6904201.A patent/NL159302B/xx not_active IP Right Cessation
  • 1969-03-19 JP JP44020483A patent/JPS5222923B1/ja active Pending
  • 1969-03-19 FR FR6907966A patent/FR2004254A1/fr not_active Withdrawn
  • 1969-03-19 BE BE730097D patent/BE730097A/xx unknown

Patent Citations (2)

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