JPH08112297A - Mold and mold forming lid for article for repairing crown of tooth - Google Patents

Abstract

PURPOSE: To generate hardly cavities, and the surface roughening in a product and to improve the manufacturing technology for a mold by forming an intermediate room with an expanded path crosssection on the midway of a sprue. CONSTITUTION: A conically recessed port 30 is formed on one end of a mold 3 formed in a mold ring 4. A sprue 31 constituted of an intermediate room 311 and a straight part 312 following this is continued to the outlet part 301 of this port 30 and the intermediate room 311 is formed by expanding the diameter of the sprue 31. In addition, the intermediate room 311 is formed into a semi-spherical shape being projected downward and the top wall 315 of the intermediate room 311 is made to be horizontal. In addition, a mold part 32 coinciding with the shape of an repaired article of a crown of tooth such as a crown is formed on the apex part of the straight part 312 following the intermediate room 311. As air admixed in a molten liq. is removed thereby in the intermediate room 311, air is hardly mixed in the molten liq. flowing into a casting part 32 to generate hardly cavities or surface roughening in an repaired article of a crown as a product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for casting a crown restoration such as a metal crown used as an artificial tooth, and a mold-molding lid used for manufacturing the mold.

[0002]

2. Description of the Related Art In a dental casting method, a metal crown restoration such as a metal crown is as shown in FIGS.
It may be cast by a pneumatic casting machine. Foundry room (1
A pressure adjusting pipe (13) connected to a pump (not shown) is projected on the outer wall of the cylindrical container (1) which constitutes (2),
The open end of the cylindrical container (1) has a removable lid (10).
Is covered with. The sealing lid (10) is provided with a mold holder (101) protruding into the cylindrical container (1),
In the cylindrical container (1), a holding cylinder (11) for holding the crucible (2) is provided at the facing portion of the mold holder (101).

When casting a crown restoration, as shown in FIG. 7, first, a crucible (2) containing an alloy as a casting material (9) is placed in a holding cylinder (11). Furthermore, a sealing lid (10)
The mold (3) is press-fitted and held in the mold holder (101), and in this state, the sealing lid (10) is covered on the opening of the cylindrical container (1). Then, by operating a pump (not shown), the air in the casting chamber (12) is sucked through the pressure adjusting pipe (13) to bring the chamber into a vacuum state and a heater provided in the holding cylinder (11). Casting material inside the melting pot (2)
(9) is melted and the lever (8) is further operated to make a cylindrical container.
(1) Invert the entire unit. Then, as shown in FIG. 9, the molten metal (90) obtained by melting the casting material (9) is mixed with the mold (3).
It falls into the receiving port (30) formed in the upper part and is accumulated in the receiving port (30) due to its surface tension. Therefore, when the molten metal (90) is completely dropped, compressed air is supplied from the pressure adjusting pipe (13), and the air pressure (P) is applied to the receiving port.
When the molten metal (90) accumulated in (30) is pushed into the lower sprue (31) and the subsequent casting portion (32), the casting is completed as shown in FIG.

However, when casting is performed using the above-mentioned conventional cylindrical container (1), there is a problem in that products such as metal crowns after the completion of casting tend to have cavities and surface roughness. It is considered that this is because the molten metal (90) poured into the receiving port (30) flows into the sprue (31) while entraining air at the contact portion between the both. That is, when the molten metal (90) is pushed into the sprue (31) by the air pressure (P), a part of the compressed air enters the contact boundary between the molten metal (90) and the receiving port (30) and further sprue (31 It is considered that the air is finally supplied to the casting chamber (12) and is then sent to the casting chamber (12) to complete the casting while remaining in the casting chamber (12), which causes cavities and the like in the product.

The present invention has been made in view of the above point, and it is "the receiving port (30) for the molten metal (90) which is open to the surface of the mold (3)."
And a sprue (31) connected to the sprue (31) and a casting part (32) following the sprue (31), and a crown restoration such as a crown is cast in the casting part (32) The problem is to make it difficult for the product to have cavities and surface roughness.

[0006]

[Technical Means] A technical means of the present invention for solving the above-mentioned problem is that "an intermediate chamber (311) having an enlarged passage cross section is formed in the middle of the sprue (31)".

[0007]

The above technical means operates as follows. Molten metal (9
(0) entrains air from sprue (31) through receptacle (30)
When it flows into the intermediate chamber (311) and reaches the intermediate chamber (311), the molten metal (90) accumulates in the intermediate chamber (311). Then, the air mixed in the molten metal (90) in the intermediate chamber (311) becomes the molten metal (90).
It will rise by the buoyancy received from and will accumulate in the upper part of the intermediate chamber (311). That is, the air mixed in the molten metal (90) is
It is removed in 1). The molten metal (90) in the intermediate chamber (311) from which the air has been removed is the sprue that follows it.
From the part (31), it flows into the casting part (32) and is cast.

[0008]

[Effect] The present invention has the following unique effects. The air mixed in the molten metal (90) is removed in the intermediate chamber (311).
Almost no air is mixed in the molten metal (90) flowing into the (32), so that the dental restoration as a product is less likely to have a nest or surface roughness.

[0009]

Embodiments of the present invention described above will now be described with reference to the drawings. The mold (3) of the embodiment of the present invention is constructed as shown in FIG. 1, and a conical recessed receiving port (30) is formed at one end of the mold (3) formed in the casting ring (4). There is.
The outlet (301) of the receiving port (30) has a sprue (3) composed of an intermediate chamber (311) and a straight portion (312) following the intermediate chamber (311).
1) are continuous, the former middle chamber (311) is a sprue (31)
It is formed by enlarging the diameter of. Then, the intermediate chamber (3
11) is formed in a hemispherical shape that is convex downward, and the top wall (315) of the intermediate chamber (311) is horizontal. Further, a casting portion (32) conforming to the shape of a crown restoration such as a crown is formed at the tip of the straight portion (312) following the intermediate chamber (311).

Next, a method of manufacturing the mold (3) will be described. The mold (3) includes a casting ring (4), a mold molding lid (5) as shown in FIG. 2 which is provided with a cover at one end open portion thereof, and further, is attached to the mold molding lid (5) and has a crown. It is made from a wax mold (6), which is made by molding restorations. As shown in FIG. 2, the molding lid (5) is a bottomed cylindrical lid body (5) made of rubber.
5) and its bottom plate (50), the conical socket molding (51) protruding in the center, and the blind hole-shaped recess (511) opened on the top surface of the socket, and the previously mentioned intermediate chamber (311). Wax insert mold (5
2), and the insert mold (52) has a hemispherical head (5
20) and a shaft-shaped convex portion (521) protruding from the flat portion of the lower surface thereof. Further, a flange (522) having a smaller diameter toward the head (520) side is formed on the outer circumference of the base end of the convex portion (521), and the flange (522) and the molding lid (5). The receiving port forming part (51) of the mold forms the receiving port (30) of the mold (3). In addition, in the above-mentioned mold forming lid (5), the insert mold (52) was formed with the convex portion (521) and the socket forming portion (51) was formed with the concave portion (511). In addition, a recess (511) may be formed in the insert mold (52) and a protrusion (521) to be inserted therein may be projected from the top of the mouth forming part (51).

The so-called lost wax method is used to manufacture the mold (3) using the mold molding lid (5) and the like. That is, a wax mold (6) having a pillar portion (61) for forming the crown restoration molding portion (62) and the straight portion (312) of the sprue (31) is prepared, and the pillar portion (61) is prepared. The tip of the mold is welded and fixed to the tip of the insert die (52) of the molding lid (5) as shown in FIG. Then, after inserting the casting ring (4) into the annular protrusion (53) provided on the outer periphery of the molding lid (5), the casting material (94) is filled into the casting ring (4) and When the above is sintered, the wax mold (6) buried in the mold material is burned down, and a mold (3) as shown in FIG. 1 having an intermediate chamber (311) near the receiving port (30) is obtained.

Next, the operation of casting a crown restoration such as a metal crown by using the above-mentioned mold (3) produced will be described. As described in the conventional example, the mold (3) is set on the closed lid (10) of the pneumatic casting machine as shown in FIG. 4, and the crucible (2) containing the alloy as the casting material (9) is set. Is inserted into the holding cylinder (11) located below the mold (3). Then, the pressure control pipe (1) protruding from the side wall of the cylindrical container (1)
A pump (not shown) connected to 3) sucks the air in the casting chamber (12) to make it vacuum, and heats the heater embedded in the holding tube (11) to heat the casting in the crucible (2). Material (9)
To melt. After that, the lever (8) is operated in the same manner as described above so that the entire cylindrical container (1) is inverted and inverted, and at the same time, a pump (not shown) is operated to move the pressure adjusting pipe (13) to the casting chamber.
Supply compressed air to (12). Then, as shown in FIG. 5, the molten metal (90) in the crucible (2) falls into the receiving port (30) formed at the end of the mold (3), and further the molten metal (90) is cooled by air (96). )
While flowing in, it flows from the receiving port (30) into the intermediate chamber (311) and fills the portion. Then, the air having a small specific gravity mixed in the molten metal (90) levitates by the buoyancy received from the molten metal (90) and accumulates in the upper part of the intermediate chamber (311), whereby the air is collected. Will be removed. Since the top wall (315) of the intermediate chamber (311) is formed horizontally in this embodiment, the cross section of the passage is sharper than that of the top wall (315) which gradually expands downward. As a result, the molten metal (A) that has entered the intermediate chamber (311) (which is at a lower pressure than the casting chamber (12)) is suddenly decompressed, and the air mixed in the molten metal (A) is reduced. There is an advantage that it can be removed efficiently.

After that, the molten metal (90) in the intermediate chamber (311), from which air has been removed, flows from the subsequent straight portion (312) to the casting portion.
It flows into (32) and the casting is completed. In the above example, the wax mold (52) mounted on the mold molding lid (5) is attached to the wax mold.
Although the strut (61) of (6) is welded and fixed, a blind hole is formed at the top of the insert mold (52), and the strut (61) is formed in the blind hole.
You may insert and fix.

In the above embodiment, the intermediate chamber (311) is formed at the inlet of the sprue (31), but it may be formed near the intermediate or outlet of the sprue (31). Intermediate room (311)
When forming the sprue (31) in the middle part, as shown in FIG. 6, a wax mold (6) in which a hemispherical bulge (63) is formed in the middle of the pillar (61) is used. This is inserted and fixed in the concave portion (511) formed in the receptacle molding portion (51) of the general mold molding lid (5), and then a normal mold manufacturing operation is performed.

In the above embodiment, the top wall (3) of the intermediate chamber (311) is
Although only 15) is formed horizontally, the bottom wall (316) facing the top wall (315) may also be formed horizontally. Further, in the above-mentioned embodiment, the cylindrical container (1) is entirely inverted and inverted.
Although the molten metal (90) in (2) was supplied to the mold (3),
The mold (3) and the crucible (2) are placed in the cylindrical container (1) in order from the bottom in an upright state, and after the inside of the cylindrical container (1) is evacuated, only the crucible (2) is inverted. Mold the molten metal (90) inside
You may make it throw in into the receiving port (30) of (3), and then inject pressurized air into the cylindrical container (1).

[Brief description of drawings]

FIG. 1 is a sectional view of a mold (3) according to an embodiment of the present invention.

[Fig. 2] Cross-sectional view of the molding lid (5)

[Figure 3] Explanatory drawing of mold making work

FIG. 4 is an explanatory diagram of a casting operation for a crown restoration.

FIG. 5 is an explanatory diagram of a casting operation for a crown restoration.

FIG. 6 is an explanatory view of manufacturing the mold (3) in which the intermediate chamber (311) is provided in the middle of the sprue (31).

FIG. 7 is an explanatory view of a conventional example.

FIG. 8 is an explanatory diagram of a conventional example.

FIG. 9 is an explanatory view of a conventional example.

[Explanation of symbols]

 (3) ・ ・ ・ Mold (30) ・ ・ ・ Receiving port (31) ・ ・ ・ Sprue (31) (32) ・ ・ ・ Casting part (311) ・ ・ ・ Intermediate chamber (52) ・ ・ ・ Nesting type

Claims (4)

[Claims] 1. A sprue (31) connected to a receiving port (30) for the molten metal (90) which is open to the surface of the mold (3), and the sprue.
(31) is followed by a casting part (32), in the casting part (32) for casting a crown restoration such as a crown, in a crown restoration mold, sprue (31) A mold for a crown restoration in which an intermediate chamber (311) having an enlarged passage cross section is formed on the way. 2. The mold for a crown restoration according to claim 1, wherein the intermediate chamber (311) has a shape in which the top wall (315) is substantially horizontal and the cross-section is reduced toward the downstream side. 3. A mold for a crown restoration according to claim 1, wherein the mold is provided in the vicinity of the receiving port (30) of the intermediate chamber (311). 4. A mold forming lid for forming a region extending from the receiving port (30) of the mold for a crown restoration according to any one of claims 1 to 3 to the intermediate chamber (311), which comprises: The receiving port forming part (5) for forming the receiving port (30) is formed in the shape of a bottom cylinder.
1) The lid body (55) raised from the inner bottom surface and the above-mentioned receiving port (30)
A wax insert mold (52) for forming a passage from the outlet of the intermediate chamber (311) to the exit of the intermediate chamber (311) is provided, and the top of the receptacle forming part (51) and the insert mold (52) are Convex part (52
A mold-molding lid that is designed to be inserted and fixed together by inserting it into the 1) and the recess (511).