US1776267A - Dental apparatus for eliminating wax from molds - Google Patents

Description

Sept. 23, 1930. F. s. MEYER 1,776,267

DENTAL APPARATUS FOR ELIMINATING WAX FROM HOLDS Filed July 2, 1927 Patented Sept. 23, 1930 PATENT OFFICE FREDERICK S. MEYER, OF MINNEAPOLIS, MINNESOTA DENTAL APPARATUS FOR ELIMINATING WAX FROM HOLDS Application filed July 2, 1927.

This invention relates to apparatus and a process for removing or eliminating the wax or plastic model from the mold for casting inlays or crowns.

In my co-pending application for U. S. Letters Patent entitled Apparatus for forming molds for crowns and inlays, Serial Number 203,237, filed July 2nd, 1927, I disclosed my apparatus, includin an improved crucible former, sprue an investment ring, with which I am able to obtain improved molds for casting gold inlays or crowns. The mold formed by my said apparatus has the plastic model enclosed therein and, of course, the material of this model must be removed before the recess in the mold can be filled with gold.

This invention has for its main object to provide highly efficient apparatus, and a novel process for quickly and efliciently removing the plastic model from the mold,

without subjecting the mold to excessive heat.

1 A further object of my invention is to provide a process for causing the wax or other plastic material within the mold to be washed out under considerable pressure, hot fluid being forced through the porous mold from end to end.

Another object of the invention is to provide apparatus comprising a container adapted to hold a supply of fluid for removing the plastic model and also adapted to retain and clamp the mold and the investment ring in .such manner that said fluid when subjected to heat will be positively circulated through the investment material of the mold, eliminating all wax or plastic material therein.

Still another object is to provide a-process wherein hot fluid may beforced under pressure through the investment material of the mold to melt and carry with it all plastic material constituting the model.

These objects and other objects of the invention will be apparent from the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views, and in which:

Serial No. 203,238.

Fig. 1 is a longitudinal section of a preferred embodiment of my eliminating apparatus having an investment ring with a mold therein attached for elimination of the wax model;

Fig. 2 is a cross section taken on the line 22 of Fig. 1; and

Fig. 3 is an elevation of the investment ring and mold detached, some portions being broken away and others shown in section. As illustrated, my apparatus preferably comprises a generally cylindrical cup member 4 closed at its lower end and formin a liquid reservoir 4 in the lower portlon thereof. A circumferentially disposed inwardly projecting annular flange 5 is provided within cup member 4 disposed directly above said liquid reservoir portion and defining the upper end thereof, said flange constituting a seat to receive one end of a cylindrical investment ring 6 having a mold formed therein for casting an inlay or crown. The height of the investment ring and mold is greater than the distance from-the flange 5 to the upper end of cup member 4, whereby one end of said investment ring will project above said cup member. The upper portion of my member 4, as shown, is somewhat diminished and provided with external threads 4 said threads being adapted to engage the threaded interior of a clamping cap 7. Cap 7 is provided with a top opening 7 a of substantially the diameter of the crucible portion 8 of a mold 8. In the type of mold illustrated, the wax model X is covered with a relatively dense inner investment 8 approximately axially disposed in the investment ring and the investment ring is filled with a less dense outer investment 8. An axial port Y, formed by the sprue in making the mold extends from the crucible portion 8 to the wax model.

A washer or packing ring 9 is disposed on the seat formed by flange 5 adapted to be engaged by the edge of the investment ring to form an air tight joint between the same and the liquid reservoir 4. Obviously, clamping cap 7 may be screwed down to securely force the investment ring 6 against so that there will be little or no opportunity its packed seat. If desired, a washer 10 may be carried in the upper end of the cap interposed between said end and the cruclble end of the investment ring.

. The process employed and the operatlon of my apparatus may be briefly described as follows:

The cup member 4 is first partially filled with water or other desirable l1qu1d to a height slightly above flange 5. Investment rin 6 having the mold and wax model X encIosed therein is disposed withm the upper portion of cup 4 engaging at one end the packed seat provided by flange 5. Cap 7 1s then inserted over the crucible end of the nvestment ring and is threadedly engaged with the upper end of cup 4 and screwed down to securely clamp the investment rlng agalnst its seat confining the liquid withln reservolr 4. As has been stated, the cup is filled with water or liquid above the level of flange 5. The joint between the lower end of the lnvestmentring and flange 5 is water tight and the bottom of the mold will be completely sealed by the water, since cup member 4 was first filled above the level of flange 5. S1nce the liquid reservoir 4 is especially adapted to hold liquid for the purpose of boiling the same, it may be properly termed a boiler.

The assembled device with the mold therein is next heated by any suitable means, as illustrated in Fig. 1, and preferably the heat is diminished or withdrawn when the water is caused to boil or shortly before. The material of the mold is sufliciently orous to permit Water and steam to be readily forced through it under pressure. The initial heating of the water within the confined reservoir 4 causes a pressure usually sufficient to thoroughly saturate the mold with cool water,

for the mold to absorb the wax. When the water comes to the boiling point, steam will, of course, be formed, increasing the pressure upon the hot water within the reservoir portion 4, steam and hot water passing upwardly through the mold and melting and disintegrating the wax and carrying the same out of the upper end of the mold through the sprue hole Y. The passage of the hot fluids through the mold continues sufliciently long after the main portion of the wax is carried through to completely wash away and remove any small deposits of wax left in the minute pores of the mold. The pressure exerted upon the confined water due to the action of heat is, of course, considerable, in the embodiment illustrated, attaining from ten to fifteen pounds pressure per square inch, which I find is adequate for the purpose intended.

.In operation the wax or plastic substance is eliminated very quickly and the heating is continued gently for a short time thereafter to insure the mold of being freed of all the compound which constitutes the model.

My novel process broadly stated, therefore, consists in subjecting one end of a mold having a Wax or fusible pattern therein to the action of hot fluid, such as water, and steam under considerable pressure to completely remove the pattern'from the opposite end of the mold. More specifically my process, therefore, consists in first sub'ecting one end of a mold having a wax mo el therein to a confined supply of Water, heating said confined Water to produce a large amount of pressure thereon, said pressure forcing said confined water and steam generated through the mold to first saturate the same and soften the wax model, said fluids passing out through the other end of said mold and largely through the sprue hole between the crucible portion of the mold and the wax model, and serving to loosen, disintegrate and melt the wax model and carry the pieces thereof through the sprue hole to the crucible.

l/Vith my process and apparatus only a relatively small amount of heat is required to completely remove the wax within the mold since a pressure is produced upon the Water even before the water reaches the boiling point and the temperature of the mold itself seldom, if ever, exceeds 212 F., since it is not directly subjected to the heat but is disposed above the reservoir 4 wherein the liquid is boiling. There can, therefore, be no danger of burning or impairing the mold and all wax or compound will be removed.

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of the parts without departing from the scope of the invention.

What is claimed is 1. In apparatus for removing the plastic model from a mold, a liquid reservoir having a seat about one end thereof for the reception of a mold, and means for retaining said mold against said seat.

2. In apparatus for removing the plastic model from a mold, a liquid reservoir of heat conductive material having a seat at one end thereof adapted to receive an investment ring with a mold therein and means for clamping said ring against said seat. I

3. In apparatus for removing the plastic model from a mold, a liquid reservoir having a seat disposed at its upper end adapted to recelve an investment ring, packing means upon said seat adapted to cause a water tight joint between one end of said investment ring and said reservoir, and means for clamping sald investment ring against said seat.

4. In apparatus for removing the plastic model from a mold, a cup-like member having a liquid reservoir in the lower portion thereof, a flange extending transversely and circumferentially of said member above said reservoir portion and adapted to receive one end of an investment ring, the lower portion of said ring being telescoped within the upper portion of said cup member, and a pressure cap engaging the crucible end of said invest ment ring and having threaded connection -with said cup member to clamp said investsaid plastic model.

6. The process of removing the plastic model from a mold. which consists in subjecting one end of a mold to the action of confined water and heating said water to cause the same to pass through said mold under pressure and melt and remove the plastic model therewithin through the opposite end thereof.

7. The process of removing the plastic model from a porous mold which consists in subjecting a mold to the action of confined water, with the sprue passage disposed outwardly and heating said water to cause the same to pass through said mold under pressure, softening and disintegrating and removing the plastic model therewithin through said sprue passage.

8. In apparatus for removing a plastic model from a mold, a liquid reservoir andmeans for securing a mold within said reservoir to confine liquid therewithin, one surface of said mold being subjected to said liquid.

9. In apparatus for removing the plastic model from a mold, a liquid reservoir, means within said reservoir for supporting a mold therein. with an end of said mold subjected to the contents of said reservoir, and means for securing said mold against displacement from said supporting means.

10. The process of making a mold which consists in embedding a fusible pattern-in self-hardening material to form a body and subjecting one end of said body to hot fluid under pressure to melt and remove said model through the opposite end of said body.

11. In apparatus for removing the plastic 'model from a mold, a boiler, apair of cooperating clamping elements movable relatively to each other, one of said elements being adapted to engage the end of a mold and having communication with said boiler to subject said mold to the discharge of said boiler.

12. In apparatus for removinga fusible pattern from a mold, a pair of cooperating clamping elements, movable relatrvely to each other, one of said clamping elements being adapted to engage one end of a mold which has embedded therein a fusible pattern, said clamping element also having communication with a source of heated fluid under pressure for causin said heated fluid to pass through said mol and soften and remove said pattern through the opposite end of said mold.

13. In apparatus for removing a fusible pattern from a mold, a pair of cooperating clamping elements movable relatively to each other, one of said elements being adapted to engage one end of an open ended mold container, which contains a mold having a fusible pattern embeddedtherein, aseat in saidclamping element forming a sealed joint between said end of said mold container and said clamping element and said clamping element having communication with a source of heated fluid under pressure for causing said fluid to pass through said-mold and soften and remove said pattern from the opposite end of said mold.

14. The process of making a mold which consists in embedding a fusible pattern in investment material within an open ended member, forming a seal between one end of said open ended member and a source of hot fluid supply under pressure and passing said hot fluid from said supply through said mold by said pressure to soften and remove said fusible pattern from the opposite end of said mold.

In testimony whereof I aflix my signature.

FREDERICK S. MEYER.

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