JPH08141002A - Crucible former - Google Patents

Abstract

PURPOSE: To provide a crucible former with which production of a casting free from casting defect and casting crack by intrusion of dust is possible. CONSTITUTION: This crucible former 11 includes a disk-shaped base plate 13 having a diameter slightly larger than the outside diameter of an embedded ring, a disk-shaped projecting part 14 having a diameter slightly larger than the bore of the embedded ring and a conical wax pattern implanting part 15 formed at approximately the center of an upper disk 14. The crucible former 11 is formed by integral molding of a polyurethane.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a crucible former.

[0002]

2. Description of the Related Art Conventionally, in the production of artificial teeth, a mold is manufactured by the lost wax method as follows. As shown in FIG. 7A, first, a model (hereinafter referred to as a wax pattern) 61 having the shape of an artificial tooth to be manufactured is made of wax. Wax pattern 6
Wax formed by molding 1 into a rod shape (hereinafter referred to as sprue)
It is joined to the tip of the truncated cone-shaped convex portion 67 of the base 63 via 62. This table 63 is called a crucible former.

Next, the crucible former 63 is
As shown in FIG. 7B, metal (generally stainless steel)
The ring (hereinafter, referred to as a buried ring) 64 is fitted.
Then, the crucible former 63 is removed from the mold 66. The remaining mold 66 is the crucible former 6
A concave portion corresponding to the conical convex portion 67 of No. 3 is formed.
The recess 68 is provided for pouring casting material into the recess during casting.
Becomes

Next, the mold 66 is put into a mold baking furnace.
At this time, as shown in FIG. 7C, the mold 66 is placed in the mold firing furnace with the gate 68 side of the mold 66 facing down. This purpose is for facilitating the discharge of the wax softened and melted by heating, or for preventing the dust generated by firing and the furnace material peeled off from the roof of the furnace from falling into the sprue 68. Is. Then, it heats with a predetermined temperature rising pattern. As a result, the wax pattern 61 and the sprue 62 are incinerated, and a cavity is formed in that portion, and at the same time, the investment material 65 is fired. For example, in the case of a mold for artificial glass-ceramic teeth, which has become widespread in recent years, the baking of the mold 66 is performed at about 800 ° C. The mold 66 is manufactured as described above.

A desired casting material such as molten metal or glass is poured into the mold 66 manufactured in this way to perform casting. When casting, the casting mold 66 is placed with the sprue 68 facing upward. The molten casting material is poured (poured) from the sprue 68 into the cavity. If necessary, pour molten metal while applying pressure by centrifugal force. 1 for casting glass-ceramic artificial teeth
Pouring is performed at 250 ° C. Since the casting material at the time of pouring is extremely hot as described above, there is a risk that the casting mold 66 will be cracked by thermal shock caused by the temperature difference between the casting material and the casting mold 66. In order to prevent such a phenomenon, immediately before pouring the mold 68
Needs to be heated to about 450 to 650 ° C. Generally, when firing the mold 66, a firing program is set such that the temperature suitable for casting is set after firing.
Pouring is performed when the temperature reaches a predetermined temperature. For glass ceramics, the mold temperature is 600 ° C when pouring.
To be In this way, the artificial tooth having a desired shape is cast.

[0006] The conventional crucible former 63 is, for example, the actual exploitation Sho 62-99213, the actual exploration 04-8321.
No. 4, Japanese Utility Model Application Laid-Open No. 57-176211, etc. These conventional crucible formers 63 are shown in FIG.
As shown in FIG. 6, when the buried ring 64 is fitted, the lower end surface of the buried ring 64 contacts the crucible former 63 more than the bottom surface portion 63a of the crucible former 63.
The outer edge portion 63b is raised by one step. Since the crucible former 63 is composed of an elastic member such as polyurethane, the elasticity thereof causes the buried ring 64 to move.
Is pressed from the outer wall side of the buried ring 64 to the extent that it does not easily fall off.

[0007]

[Problems to be Solved by the Invention]
The dust generated by the baking of the mold, especially the iron powder generated by the oxidation of the stainless buried ring and the carbon powder generated by the incineration of the wax are attached or scattered.

The mold 66 produced by the conventional crucible former 63 corresponds to the bottom surface portion 63a of the crucible former 63 with which the lower end surface of the above-mentioned buried ring 64 abuts, as shown in FIG. 7 (C). Then, a bottom surface (hereinafter, referred to as a sprue surface) 66a forming the same plane as the lower end surface of the buried ring 64 is formed on the sprue 68 side. Therefore, when the sprue surface 66a of the mold 66 is placed inside the mold firing furnace with the sprue 68 facing downward, the dust 69 is scattered between the furnace floor 71 of the mold firing furnace and the sprue surface 66a. If they come into contact with each other, dust will adhere.

The dust 6 attached to the sprue surface 66a in this manner
9 is caught in the mold 66 at the time of pouring, and causes dust 69 to be mixed into the cast body (casting defect) and cracks of the cast body due to dropping of dust. For example, at the time of pouring, when the mold 66 is taken out from the mold firing furnace and the pouring gate 68 is directed to the pouring direction, dust 69 attached to the sprue surface 66a in the vicinity of the opening end portion of the sprue 68 is in this process. It may fall inside and get caught in the casting. Further, even when pressure casting is performed by centrifugal force or the like after pouring, a slight vibration or air flow occurs, so that dust 69 adhering to the sprue surface 66a of the mold 66 may fall into the sprue 68. .

The above-described problems such as casting defects due to dust adhering to the sprue surface 66a and cracking of the cast body are caused not only in the casting of artificial teeth but also in casting by the general lost wax method using a crucible former. Is also a problem.

The present invention has been made in view of the above circumstances, and provides a crucible former capable of producing a cast body free from casting defects and cracks in the cast body due to the inclusion of dust.

[0012]

According to the present invention, there is provided a base portion, a convex portion formed on a surface of the base portion, the convex portion being fitted inside a buried ring, and a substantially central portion of the convex portion. A crucible former comprising a formed wax pattern planting part.

Further, the present invention is a crucible former comprising a base part and a substantially conical pyramidal wax pattern planting part formed on the surface of the base part, wherein the wax pattern planting part is provided. The tapered surface of the crucible former is formed so as to extend from an end portion of a region in contact with a lower end surface of the buried ring to an apex when the buried ring is fitted in the recess. provide.

[0014]

The crucible former of the present invention has the convex portion fitted inside the buried ring formed on the surface of the base. As a result, in the unfired body of the mold from which the crucible former has been removed after the burial operation, the sprue surface is located inside the plane including the lower end surface of the burial ring. Therefore,
When placed on the hearth of a mold baking furnace with the sprue face down, the furnace floor and the sprue face do not contact. As a result, there is almost no possibility that dust or the like scattered on the hearth will adhere to the sprue surface.

The crucible former of the present invention is
The wax pattern planting portion is formed in a conical shape, and its tapered surface is formed so as to extend from the end portion of the region that comes into contact with the lower end surface of the buried ring to the apex when the buried ring is fitted in the recess. As a result, the unfired body of the mold from which the crucible former has been removed after the burying operation has no sprue surface and all sprues are formed. Therefore, when placed on the hearth of the mold baking furnace with the gate face down, the hearth and the gate do not contact. As a result, there is almost no possibility that dust or the like scattered on the hearth will adhere to the sprue.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 FIGS. 1 (A) and 1 (B) are a plan view and a longitudinal sectional view, respectively, showing a first example of the crucible former of the present invention.

The crucible former shown by 11 in the figure has a disk-shaped base portion (φ48 × 8 mm) 13 having a diameter larger than the outer diameter of the buried ring 12, and the buried ring 1.
2. A disk-shaped convex portion (φ42 × 10 mm) 14 having a diameter slightly larger than the inner diameter of 2 and a conical wax pattern planting portion (φ25 × 2) formed substantially in the center of the upper disk 14.
0 mm) 15. Crucible Former 11
Is made of an elastic material such as polyurethane or polyvinyl. The crucible former 11 is integrally formed.

Using the crucible former 11 having such a structure, a mold is manufactured according to the lost wax method as follows. First, the wax pattern 16 is joined to the tip of the wax pattern planting portion 15 via the sprue 17.

Next, the convex portion 1 of the crucible former 11
As shown in FIG. 2, 4 is fitted into a buried ring (φ43 × 60 mm, wall thickness 1.0 mm) 12 made of stainless steel. The diameter of the convex portion 14 is the inner diameter (φ41.
It is slightly (1 mm) larger than 0 mm. Therefore, when the crucible former 11 is fitted into the burial ring 12, the crucible former 11 is fitted while being slightly deformed. The buried ring 12 has a base portion 13 and a convex portion 1.
It is set up to the step of 4. The convex portion 14 is the buried ring 1
Acts as a buried ring stop for mounting 2 in place. After fitting into the burial ring 12, the elastic force of the crucible former 11 presses the burial ring 12 from the inside so as not to easily fall off.

Next, the investment material 18 is placed in the investment ring 12.
Pour. When left for about 1 hour, the investment material 18 is completely solidified. Then, the crucible former 11 is removed to obtain a mold unfired body 19 as shown in FIG. The unfired body 19 has a sprue surface 20 corresponding to the convex portion 14 of the crucible former 11 and a lower end surface 1 of the burial ring 12.
It is located inside the plane including 2a. Further, the sprue 21 corresponding to the wax pattern planting portion 15 is formed.

Next, the unfired body 19 of the mold is placed on the hearth 22 of the mold firing furnace with the gate 21 down, as shown in FIG. Then, it heats with a predetermined temperature rising pattern. As a result, the wax pattern 16 and the sprue 17 are incinerated, and a cavity is formed in that portion, and at the same time, the investment material 1
8 is fired. As a result, a mold is obtained.

As explained above, the unfired body 19 of the mold obtained by using the crucible former 11 of this embodiment.
Corresponds to the convex portion 14 of the crucible former 11, and the sprue surface 20 is located inside the plane including the lower end surface 12 a of the buried ring 12. Therefore, when placed on the hearth 22 of the mold firing furnace, the lower end surface 1 of the buried ring 12 is
Only 2a contacts the hearth 22, and the sprue surface 20 does not contact the hearth 22. Therefore, dust 23 generated by firing of the mold scattered on the hearth 22, especially iron powder generated by oxidation of the stainless buried ring and carbon powder generated by incineration of wax are generated on the hearth 22. Does not adhere. Also,
Lower end surface 12a of the buried ring 12 that is only in contact with the hearth 22
Since the wall thickness is as thin as 1.0 mm, dust 23 is unlikely to adhere. Moreover, even if they are attached, the amount is very small. Moreover,
Since it adheres to the outermost edge of the mold furthest from the sprue 21, the possibility that the dust 23 will be caught in the artificial tooth to be cast is very low.

Further, the mold manufactured by using the crucible former 11 of the present embodiment, when placed with the sprue 21 on top after firing, the dust 23 adhering to it will not be affected by vibration during casting. Buried ring 1
2 falls on the sprue surface 20 located slightly inside the lower end surface 12a. Therefore, there is almost no possibility that the dropped dust 23 will enter the sprue 21.

Embodiment 2 FIGS. 4 (A) and 4 (B) are a plan view and a vertical sectional view showing a second embodiment of the crucible former of the present invention.

The crucible former indicated by reference numeral 41 in the drawing is a base portion 43 having a diameter larger than the outer diameter of the buried ring 42, and a substantially conical wax pattern plant formed on the base portion 43. The standing portion 44 and the ring support portion 45 formed on the outer peripheral edge of the base portion 43 are provided. The taper surface 44 a of the wax pattern planting portion 44 has a buried ring 42.
End portion 46 in the region of the base portion 43 that abuts the lower end surface 42a of the
To the apex of the wax pattern planting portion 44. Further, the ring support portion 45 is inclined slightly inward so as to press the buried ring 42 from the outside so that the buried ring 42 does not easily drop from the crucible former 41. Crucible Former 4
1 is made by integral molding.

Using the crucible former 41 having such a structure, a wack pattern 47 and a sprue 48 are attached to the tip of the wax pattern planting portion 44 as shown in FIG. 5 in the same procedure as in the first embodiment. Join through.

Next, the buried ring 42 is fitted inside the ring support portion 45 of the crucible former 41. Since the ring support portion 45 is slightly inclined inward, it is fitted while being slightly deformed. The lower end of the buried ring 42 is the base 4
3 is positioned between the wax pattern planting portion 44 and the ring support portion 45 above. After being fitted into the burial ring 42, the elastic force of the crucible former 41 presses the burial ring 42 from the outside so as not to easily fall off.

Next, an investment material 49 is placed in the investment ring 42.
Pour. When left for about 1 hour, the investment material 49 is completely solidified. After that, the crucible former 41 is removed to obtain a mold unfired body 50 as shown in FIG. The unfired body 50 has a substantially funnel-shaped spout 51 that corresponds to the wax pattern planting portion 44 and extends from the lower end surface 42 a of the buried ring 42 to the center. Therefore, there is no sprue surface.

Then, the unfired body 50 of the mold is placed on the hearth 42 of the mold firing furnace with the gate 51 down, as shown in FIG. Then, it heats with a predetermined temperature rising pattern. As a result, the wax pattern 47 and the sprue 48 are incinerated, and a cavity is formed in that portion, and at the same time, the investment material 4
9 is fired. As a result, a mold is obtained.

As explained above, the unfired body 50 of the mold obtained by using the crucible former 41 of this embodiment.
Is a substantially funnel-shaped spout 51 that extends from the lower end surface 42a of the buried ring 42 to the center corresponding to the wax pattern planting portion 44.
It is equipped with. In other words, the wax pattern planting section 4
The skirt of the tapered surface 44a of No. 4 is in contact with the lower end surface 42a of the buried ring 42 at an acute angle, and the portion corresponding to the wax pattern planting portion 44 becomes the sprue 51. That is, the entire bottom surface of the mold is the sprue 51. Therefore, when placed on the hearth 52 of the mold firing furnace, the buried ring 42
Only the lower end surface 42a of the core contacts the hearth 52. Therefore, scattered dust 53 does not adhere to the hearth 52. Further, since the lower end surface 42a of the buried ring 42 that is only in contact with the hearth 52 has a thin wall thickness of 1.0 mm, dust 53 is unlikely to adhere. Moreover, even if they are attached, the amount is very small. Moreover,
Since it adheres to the outermost edge of the mold furthest from the sprue 51, the possibility that the dust 53 will be caught in the artificial tooth to be cast is very low.

In the above-described Examples 1 and 2, the crucible former used for manufacturing the mold for casting the artificial tooth was described as an example, but the present invention is not limited to this and a general lost wax method is used. It may be a crucible former used.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications and applications are possible within the scope of the present invention. . Here, the summary of the present invention is summarized as follows.

(1) A base part, a convex part formed on the surface of the base part and fitted in the buried ring, and a wax pattern planting formed substantially in the center of the convex part. A crucible former having a part.

According to the invention of (1), there is provided the convex portion fitted inside the buried ring formed on the surface of the base portion. As a result, in the unfired body of the mold from which the crucible former has been removed after the burial operation, the sprue surface is located inside the plane including the lower end surface of the burial ring. Therefore, when placed on the hearth of the mold baking furnace with the sprue face down, there is no contact between the furnace floor and the sprue surface, so dust scattered on the furnace floor may adhere to the sprue surface. rare. As a result, it is possible to prevent dust and the like from entering the inside of the mold through the sprue, and it is possible to manufacture a mold that does not cause casting defects or cracks in the cast body due to the mixing of dust.

(2) The crucible former according to (1), further comprising a ring support portion that is in contact with an outer wall surface of the buried ring when a convex portion is fitted to the buried ring. According to the invention of (2), there is provided a convex portion fitted inside the buried ring formed on the surface of the base portion. As a result, in the unfired body of the mold from which the crucible former has been removed after the burial operation, the sprue surface is located inside the plane including the lower end surface of the burial ring. Therefore, when placed on the hearth of the mold baking furnace with the sprue face down, there is no contact between the furnace floor and the sprue surface, so dust scattered on the furnace floor may adhere to the sprue surface. rare. As a result, it is possible to prevent dust and the like from entering the inside of the mold through the sprue, and to manufacture a mold that does not cause casting defects or cracks in the cast body. Furthermore, since the ring support portion contacts the outer wall surface of the buried ring when the convex portion is fitted to the buried ring, the buried ring is positioned at a fixed position.

(3) A crucible former comprising a base part and a wax pattern planting part having a substantially conical shape formed on a surface of the base part, wherein the wax pattern planting part has a tapered surface. The crucible former is characterized in that when the buried ring is fitted to the base part, the crucible former is formed so as to reach an apex from an end of a region in contact with the lower end surface of the buried ring.

According to the invention of (3), when the wax pattern planting portion is formed in a conical shape and the taper surface thereof is fitted into the recess, the end of the region which comes into contact with the lower end surface of the buried ring. It is formed from the part to the top.
As a result, the unfired body of the mold from which the crucible former has been removed after the burying operation has no sprue surface and all sprues are formed. Therefore, when placed on the hearth of the mold baking furnace with the gate face down, the hearth and the gate do not contact. As a result, there is almost no risk that dust scattered on the hearth will adhere to the sprue, preventing dust from entering the inside of the mold from the sprue and causing casting defects and cracks in the cast body. It is possible to manufacture a mold without a mold.

(4) The crucible former according to (3), further comprising a ring support portion which is in contact with the outer wall surface of the buried ring when the wax pattern planting portion is fitted in the buried ring.

According to the invention of (4), when the wax pattern planting portion is formed in a conical shape and the tapered surface thereof is fitted into the recess, the end of the region which comes into contact with the lower end surface of the buried ring. It is formed from the part to the top.
As a result, the unfired body of the mold from which the crucible former has been removed after the burying operation has no sprue surface and all sprues are formed. Therefore, when placed on the hearth of the mold baking furnace with the gate face down, the hearth and the gate do not contact. As a result, there is almost no risk that dust scattered on the hearth will adhere to the sprue, preventing dust from entering the inside of the mold from the sprue and causing casting defects and cracks in the cast body. It is possible to manufacture a mold without a mold. Furthermore, since the ring support portion contacts the outer wall surface of the buried ring when the buried ring is fitted, the buried ring is positioned at a fixed position.

[0040]

As described above, the crucible former of the present invention has the convex portion fitted on the inside of the burial ring formed on the surface of the base portion, so that the crucible former can be mounted after the burial operation. The unbaked body of the removed mold has the sprue surface located inside the plane including the lower end surface of the burial ring.
Therefore, when placed on the hearth of the mold baking furnace with the sprue face down, there is no contact between the furnace floor and the sprue surface, so dust scattered on the furnace floor may adhere to the sprue surface. rare. As a result, as a result, it is possible to prevent dust and the like from entering the inside of the mold through the sprue, and to manufacture a mold that does not cause casting defects or cracks in the cast body.

The crucible former of the present invention is
The wax pattern planting portion is formed in a conical shape, and its tapered surface is formed so as to reach from the end to the apex of the region in contact with the lower end surface of the buried ring when the buried ring is fitted in the recess. In the unfired body of the mold from which the crucible former has been removed after the burying operation, the sprue surface is entirely formed without the sprue surface. Therefore, when placed on the hearth of the mold firing furnace with the gate face down, the hearth and the gate do not contact, and there is little risk that dust, etc. scattered on the hearth will adhere to the gate. . As a result, it is possible to prevent dust and the like from entering the inside of the mold through the sprue, and to manufacture a mold that does not cause casting defects or cracks in the cast body.

[Brief description of drawings]

1A and 1B are a plan view and a longitudinal sectional view, respectively, showing a first embodiment of a crucible former of the present invention.

FIG. 2 is a cross-sectional view showing the mold after the burying operation using the crucible former of FIG.

FIG. 3 is an explanatory view showing a state in which an unfired body of a mold manufactured using the crucible former of FIG. 1 is placed on a hearth.

4A and 4B are respectively a plan view and a vertical sectional view showing a second embodiment of the crucible former of the present invention.

5 is a cross-sectional view showing the mold after the burying operation using the crucible former of FIG.

6 is an explanatory view showing a state in which an unfired body of a mold manufactured by using the crucible former of FIG. 2 is placed on a hearth.

FIG. 7A is an explanatory view showing a conventional crucible former, FIG. 7B is an explanatory view showing a mold after the burying operation using the conventional crucible former, and FIG. Explanatory drawing which shows the state which mounted the unbaked body of the mold manufactured using the crucible former on the hearth.

[Explanation of reference numerals] 11,41 ... Crucible former, 12, 42 ... Buried ring, 13, 43 ... Base part, 14 ... Convex part, 15, 44
... Wax pattern planting part, 16, 47 ... Wax pattern, 17, 48 ... Sprue, 18, 49 ... Investment material, 1
Reference numeral 9, 50 ... Unfired body, 20 ... Gate surface, 21, 51 ... Gate, 22, 52 ... Hearth, 45 ... Ring support section.

Claims (3)

[Claims] 1. A base portion, a convex portion formed on a surface of the base portion and fitted into an embedded ring, and a wax pattern planting portion formed substantially at the center of the convex portion. A crucible former characterized by comprising: 2. A crucible former comprising a base portion and a substantially conical pyramidal wax pattern planting portion formed on a surface of the base portion, wherein a tapered surface of the wax pattern planting portion is provided. A crucible former, characterized in that, when the buried ring is fitted to the base portion, the crucible former is formed so as to extend from an end of a region in contact with a lower end surface of the buried ring to an apex. 3. The crucible former according to claim 3, further comprising a ring support portion that is in contact with an outer wall surface of the buried ring when the wax pattern planting portion is fitted in the buried ring.