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
  • B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
  • B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor

Definitions

• the invention relates to a method for mixing wet molding materials, in particular wet molding sands, for foundry purposes, by premixing the dry components in a container with a free surface, adding the wet components after dry mixing and then homogenizing them with the dry components by further mixing to give the wet molding material.
• Mixing processes for foundry molding materials of the aforementioned type are carried out in different mixer designs.
• Common to these mixers is always a standing or revolving, trough-like container, which is provided with a discharge opening on the circumferential or bottom side and engages in different types of mixing tools from above.
• Filling with dry components and adding the moist components is done from above.
• the dry components are composed of granular, free-flowing bulk materials, such as new sand and processed old sand, as well as dusty, likewise almost dry bulk materials, such as coal dust, etc.
• the primary binder used is sodium bentonite, which is derived from mineral Layer particles exist that are activated and swell when water is added.
• the process is due to an incorporation of the water molecules in the layered mineral. Furthermore, water glass is sometimes used as a binder, which dries under the influence of air and creates the bond.
• the binders or the binder components like the dry components, are applied to the free surface from above.
• the wet molding material is produced in batches, with particular emphasis being placed on short mixing times in order to be able to continuously provide the wet molding material on the molding machine.
• the entire mixing cycle which is essentially determined by the type of mixing tools and the circulation speed within the mixer, is at least two minutes.
• the object of the invention is to reduce the mixing time for a given mixer design and to achieve a better mixing result.
• the moist components are introduced into the premixed dry components below the free surface. It has been found that the mixing time in the area of the wet mixing cycle can be reduced by up to half a minute, regardless of whether bentonite- or water glass-bonded molding materials are used. It has also been shown that it is much less difficult to achieve an absolutely homogeneous mixture. The following considerations can be considered as the cause for this:
• the process according to the invention can be used not only to reduce the mixing time, but - with the same mixing time - to improve the mixing result.
• the process according to the invention achieves a further advantage which is important for the mixer operation and the mixing result: when the moist components are added to the free surface of the material to be mixed, the parts of the mixer lying above the surface inevitably also occur. As a result, when the dry components are added and in the dry mixing phase, caking occurs in the areas of the mixer wetted in the previous batch, which will grow steadily over a longer operating period. These cakes gradually dry out from the contact surface and break off from time to time. They are then transported under the mix and are no longer dissolved there, so that there are inhomogeneities, which in turn lead to shape and casting errors.
• the wet components can be injected or injected into the dry mix, the overpressure, of course, being chosen such that the wet components cannot, or can only, penetrate to the surface.
• the moist components are added to the dry mix at a number of locations, preferably evenly distributed.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Processing Of Solid Wastes (AREA)
• Producing Shaped Articles From Materials (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6284438

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Citations (3)

Family Cites Families (1)

• 1985
  • 1985-10-25 DE DE19853537980 patent/DE3537980A1/de not_active Withdrawn
• 1986
  • 1986-06-12 DE DE8686108060T patent/DE3663463D1/de not_active Expired
  • 1986-06-12 EP EP86108060A patent/EP0219607B1/fr not_active Expired
  • 1986-08-22 US US06/899,398 patent/US4818112A/en not_active Expired - Fee Related

Patent Citations (3)

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