Mixing Support for Castable Material

This invention relates in general to the field of ceramic casting and in particular to apparatus for supporting a mixture of castable ceramic material such as dental porcelain or the like.

The production of ceramic material is generally accomplished by mixing together one or more suitable clay substances with water to form a plastic substance which is thereafter cast, molded, or otherwise worked into a desired shape. The ceramic material hardens and dries to retain this shape, and subsequent curing or firing of the ceramic material produces a hardened cast product whose physical characteristics are determined by factors such as the chemical composition of the clay, and the time and duration of firing.

Since the workability of the ceramic material mixture during formation of the finished product is determined by the wetness of the mixture, it is important to maintain the ceramic material mixture in a desired range of wetness which allows the material to be readily worked. This is particularly important in the working of dental porcelain materials used in the preparation of false teeth, for example, inasmuch as the fit and durability of the finished product is of primary importance to the person being fitted with the teeth. It has been the practice, in the preparation of porcelain dental materials, to intermix the desired powdered porcelain material with water or another suitable liquid to provide a porcelain mixture of desired consistency. This porcelain mixture is typically supported on a work surface made of a hard and impervious material such as glass or the like, from which the technician can withdraw the material as needed.

It has been found that the porcelain mixture rapidly commences to harden or "set" because of liquid evaporation from the mix. In practice, it is frequently necessary to stir or "turn over" the porcelain mix as frequently as once each minute, possibly adding water or other liquid as necessary to maintain the mix in a desired state of plasticity. This frequent need of attention to the ceramic mix distracts the attention of the dental technician from his task of crafting the false teeth or other product, and is generally wasteful of time and effort. If the porcelain mixture is not turned over and supplied with sufficient moisture, however, the mixture rapidly becomes too hard for use and must be re-mixed by adding water.

The foregoing problems are substantially alleviated according to the present invention, which in general terms comprises a support surface which is made of porous material and which is supplied with liquid while supporting a quantity of castable ceramic material. A flow of a suitable liquid such as water or the like is maintained through the porous material to the work surface, so that a quantity of ceramic castable material disposed on the work surface can receive a supply of liquid at a relatively steady rate. The liquid supply can be provided by a liquid reservoir disposed beneath the porous material, within which is maintained a supply of liquid at a pressure sufficient to establish liquid flow through the porous material from the reservoir to the superadjacent work surface.

Other objects and advantages of the present invention will become more readily apparent from the following description of a disclosed embodiment, taken along with the drawing in which:

FIG. 1 shows a pictorial view of the disclosed embodiment of the present invention;

FIG. 2 shows a top plan view of the disclosed embodiment; and

FIG. 3 shows a vertical section view taken along line 3--3 of FIG. 2.

Turning to FIG. 1, there is shown a mixing support apparatus indicated generally at 10 and having an upper wall 11 comprising a surface for mixing materials such as castable ceramics or the like. The apparatus 10 is further defined by a lower wall 12, side walls 13 and 14, a rear wall 15 (shown in FIG. 2), and a front wall 16. As best shown in FIG. 3, the upper wall 11 and the lower wall 12 are spaced apart from each other to define a reservoir 17 which is further defined in the disclosed embodiment by the two side walls 13 and 14, the front wall 16, and the rear wall 15.

Access to the reservoir 17 is provided by a pair of openings 21 and 22 formed through the upper wall 11 of the mixing support apparatus. Each of the openings 21 and 22 is surrounded by wells 23 and 24, respectively, which are secured to the upper wall 11 in liquid-tight relation and which terminate at open ends 23a, 24a a distance spaced above the upper wall. Although only a single opening 21 may be required for admitting liquid to the reservoir 17, it will be appreciated that the presence of a second opening 22 into the reservoir provides an air vent which greatly facilitates the complete filling of the reservoir with water or another desired liquid without unwanted entrapment of air within the reservoir.

Either or both of the wells 23 and 24 can be provided with a suitably-calibrated measuring scale 25 for conveniently determining the level of liquid within the well, for a purpose which will become apparent.

Since the reservoir 17 is intended to receive a quantity of liquid, all of the reservoir-defining walls except for the upper wall 11 should be constructed of a suitable non-porous material. It can be seen from FIG. 3 that the mixing apparatus is fabricated with an upper section 28 and a lower section 29 which have been suitably and preferably permanently joined together as by cementing or the like, although it will be understood that these upper and lower sections can alternatively be of unitary construction.

The upper wall 11 in the disclosed embodiment includes several regions 30 which are substantially porous to water or other liquids used in preparing ceramic mixtures of interest, with the porosity of the regions 30 extending through the thickness of the upper wall 11 into communication with the reservoir 17 within the mixing apparatus 10. The porous surface regions 30 are surrounded by a substantially non-porous area 31, although it will be understood that the entire upper surface area of the wall 11 can alternatively be a surface region of porosity in the manner of the regions designated 30. An upper wall 11 having one or more porous surface regions 30 as well as a non-porous area 31 can advantageously be provided by a porous ceramic tile which is coated with a nonporous glaze or another suitable nonporous finish throughout the desired nonporous area 31. The porous surface regions 30 are provided simply by the absence of the glaze or other nonporous surface. Alternative constructions will be within the abilities of those skilled in the art.

Considering the operation of the disclosed embodiment, it is assumed that the reservoir 17 has been filled with water or another liquid to a suitable level, as exemplified at 32 in FIG. 3, which is above the upper surface of the upper wall 11. It will be appreciated that the liquid within the reservoir 17 contacts the underside 18 of the upper wall 11 at some hydrostatic pressure which is determined by the elevation of the liquid within the wells 23 and 24. This hydrostatic pressure of the liquid in the reservoir 17 causes the liquid to flow upwardly through the upper wall 11 and to emerge at the porous surface regions 30 of the upper wall, so that the porous surface regions are moistened by the flow of liquid from the reservoir 17. The amount of liquid which flows through the upper wall 11 to the porous surface regions 30 is directly proportional to the elevation of the fill level 32 above the upper surface of the upper wall.

The ceramic mixture is prepared in the conventional manner and is disposed on one or more of the porous surface regions 30. By providing several separate porous regions 30 on the upper wall 11, a corresponding number of different ceramic materials can be separately mixed and maintained in a moistened state. In dental work, for example, several porcelain mixtures of different color shades can be maintained on the corresponding separate porous surface regions 30. The nonporous region 31 is also available, if desired, to provide a relatively hard nonporous work surface for mixing or for other purposes.

It will be understood, of course, that the foregoing relates only to a disclosed embodiment of the present invention, and that numerous changes and modifications may be made therein without departing from the spirit and the scope of the invention as defined in the following claims.