JP2911390B2 - Casting method and casting apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method and a casting apparatus suitable for producing relatively small castings, such as ornaments and dental prostheses, which are often made of precious metals.

[0002]

2. Description of the Related Art Ornaments such as rings, pendants, brooches, tie pins and the like, and dental prostheses, etc., are made of precious metals such as platinum, gold and silver, and expensive metals such as cobalt chrome alloys and titanium. Many.

[0003] These are generally prepared by using a crushing mold such as a gypsum or phosphoric acid made by the lost wax method.
It is manufactured by injecting and casting a molten metal of a metal melted in a crucible into a mold, but after injecting the molten metal into the mold,
A pressure casting method of pressurizing and casting a chamber in which a mold is arranged and a centrifugal casting method of injecting a molten metal while rotating the mold and casting the molten metal by centrifugal force are mainly employed.

[0004] As the mold, a runner vertically extending from a gate formed on the upper surface and extending in a column shape and branching from the columnar portion, and an object provided at the tip of a branch portion of the runner, respectively. (Hereinafter referred to as a “tree mold”) having a cavity space of a casting to be formed, or extending vertically in a column shape from a gate formed on the upper surface, spreading in a disk shape at the lower end thereof, and further in a disk shape. A mold (hereinafter, referred to as a “disc-shaped mold”) having a runner extending radially from a portion and a cavity space of a target casting provided at the tip of the radially extending portion of the runner is often used. Used.

[0005] These castings are required to have a fine and complicated shape due to the requirement of decorativeness and compatibility with the prosthetic part of the teeth. It is an essential requirement that the product does not have casting defects such as nests (cavities due to residual gas) in its appearance so as not to impair the function.

[0006]

However, when a metal having a high melting point, such as platinum, is used, nests are likely to be formed at the bottom of the groove when a design having a deep groove is formed according to the pressure casting method. There was a problem.

Further, when a tree-shaped mold having three or more stages is employed in the pressure casting method, there is a problem that insufficient casting and cavities are likely to occur in the middle stage.

Further, in the case of the centrifugal casting method, since the remaining gas is likely to accumulate on the surface of the cavity space of the casting opposite to the direction of the centrifugal force, sesame nests are formed on that portion of the casting. There was a problem that it often appeared.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to produce a relatively small-sized and complicated-shaped casting, particularly using a metal having a high melting point. An object of the present invention is to provide a casting method and a casting apparatus in which a nest does not occur at the bottom of a groove and a sesame nest does not occur at a specific location.

[0010]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that in a conventional pressure casting method, when pouring a molten metal into a mold, the mold is moved around its central axis. It has been found that, when the injection is carried out in a rotated state, it is possible to prevent nests from being formed at the bottom of the groove or sesame nests from being formed at specific locations, thereby completing the present invention.

That is, according to the casting method of the present invention, in a casting method in which a molten metal of a metal melted in a crucible is poured into a mold and then cast under pressure, the crucible and the mold are covered with a lid.
This chamber is placed in a chamber that can be closed by the body.
While the interior of the mold is being depressurized and the mold is rotated about its central axis, the molten metal is injected into the mold . After the injection of the molten metal is completed, the pressurized gas is injected into the mold.
It is introduced into the chamber and cast.

Further, the casting apparatus of the present invention has a chamber which can be opened and closed by a lid, a pressurized gas introducing pipe and a suction pipe connected to the chamber, and can be tilted upward inside the chamber by an external operation. A crucible supported by a heating means for heating and melting the metal placed in the crucible, a mold placing table placed below the crucible, and a mold placed on the mold placing table In a casting apparatus in which the mold mounting table and the mold are arranged such that the molten metal of the molten metal is poured into the gate of the mold when the crucible is tilted, the mold mounting table is mounted thereon. Driving means for rotating around a central axis of the mold to be placed is provided.

[0013] In the present invention, the mold is a crushing mold, a sprue formed on the upper surface, a columnar space extending vertically from the sprue, and a horizontally extending disk communicating with the lower end of the columnar space. Having a runner consisting of an annular space, a branch space extending radially from the disk-shaped space, and a cavity space of a target casting communicated with the tip of the branched space (tree mold) Or a crushing mold, a runner comprising a sprue formed on the upper surface, a columnar space extending up and down from the sprue, and a branch space extending in a branch from the columnar space, and the branch space (A disk-shaped mold) having a cavity space of a target casting which is communicated with the tip of the mold is preferably used.

In the present invention, the central axis of the mold means, for example, when a plurality of cavity spaces of a casting are provided, an axis centered on each cavity space.
Usually, the runner extending up and down becomes its central axis, and in many cases, when the mold has a cylindrical shape, the axis of the cylinder becomes the central axis, and when the mold has a prismatic shape, the upper and lower end surfaces thereof The axis connecting the centers of the two is the central axis.

[0015]

According to the present invention, a driving means for rotating the mold mounting table is provided, and the inside of the chamber in which the crucible and the mold are arranged is provided .
Is reduced, and the molten metal is poured into the mold while the mold is rotated, so that the molten metal is sequentially filled from the rotation delay direction without closing the runner at one time. For this reason, the remaining air is easily discharged through the runner, and if it remains, the remaining air is shifted to a position where there is no problem as a casting, that is, a position which has left the cavity space of the target casting.

At the same time as the molten metal is injected into the mold, a pressurized gas is introduced into the chamber from the pressurized gas introduction pipe to pressurize the interior of the chamber. It is quickly filled to every corner of the internal space.

Further, since the mold is rotated about its central axis, the inflow condition and the outgas condition under the action of the centrifugal force in all the cavity spaces become uniform, so that the uniformity of the cast product is achieved. .

As a result, for example, even in the case of a casting having a shape having a deep groove, nests are prevented from being formed at the bottom of the groove, and sesame nests are prevented from being formed at specific locations in the casting. You. Therefore, the yield of the casting is improved.

[0019]

1 to 3 show one embodiment of a casting apparatus according to the present invention. FIG. 1 is a schematic perspective view in which a part of the casting apparatus is cut away, FIG. 2 is a plan sectional view of a mold used in the casting apparatus, and FIG. 3 is a side sectional view of the mold.

As shown in FIG. 1, this casting apparatus 11
It has a chamber 12 that can be opened and closed by a lid (not shown), a crucible 13 is disposed above the chamber 12, a mold mounting table 14 is disposed below the crucible 13, and a mold 15 is mounted on the mold mounting table 14. Is to be placed. The chamber 12 has a pressurized gas introduction pipe 25.
Are connected, and the chamber 12 is closed with the lid closed.
A pressurized gas B is introduced into the inside to pressurize the inside.

The crucible 13 has a high-frequency oscillation coil 16 wound around its outer periphery, and one end 16 a of the high-frequency oscillation coil 16.
Is a support plate 17a opposed to the crucible 13
17b is connected to one support plate 17a, and the other end 16b of the high-frequency oscillation coil 16 is connected to the other support plate 17b. Rotation shafts 18a and 18b are connected to the support plates 17a and 17b, respectively.
It is rotatably supported through the chamber 12.
Outside the chamber 12, a handle 19 is provided at an end of one rotating shaft 18a, and the other rotating shaft 18b is hollow, and a coil cooling for cooling the high-frequency oscillation coil 16 from the end thereof. Water A is introduced. Then, outside the chamber 12, the handle 1
By operating the crane 9, the crucible 13 can be tilted.

In this embodiment, the crucible 13
The metal in the crucible 13 is heated and melted by high-frequency induction heating by winding a high-frequency oscillation coil 16 around the outer periphery of the crucible. However, the heating method is not limited. Can also.

When the crucible 13 is tilted, the molten metal is transferred to the mold placing table 14 and the mold 15 placed thereon.
5 is disposed at a position where it is poured into the gate 26. A support shaft 20 is connected to the center of the bottom of the mold mounting table 14, and the support shaft 20 is rotatably supported through the bottom of the chamber 12, and a pulley 21 is provided at an end thereof. On the other hand, a motor 22 is provided outside the chamber 12.
A belt 24 is stretched over a pulley 23 provided on the motor 22 and a pulley 21 provided on the support shaft 20, and the support shaft 20 and the mold mounting table 14 are driven by the motor 22. Is to rotate. When the mold 15 is placed on the mold mounting table 14, the support shaft 20 coincides with the center axis of the mold 15.

As shown in FIGS. 2 and 3, the mold 15 is a crushable mold such as a gypsum-based or phosphoric acid-based mold, and has a columnar shape as a whole, and a gate 26 is formed on the upper surface. A column-shaped space 27 extending vertically from the gate 26 is provided inside.
a, a disk space 27b communicating with the lower end of the columnar space 27a and expanding in the horizontal direction, and a plurality of branch spaces 27c radially extending from the outer periphery of the disk space 27b. Is formed, and further, the branch space 2 of the runner 27 is formed.
7c, the cavity 28 of the target casting
Are formed. The cavity space 28 is in the shape of a decorative product such as a ring, a pendant, a broach, a tie pin, or a target casting such as a dental prosthesis. In this embodiment, the cavity space 28 is in the shape of a ring. .

Next, an embodiment of the casting method of the present invention using the casting apparatus 11 will be described. First, with the crucible 13 in a vertical position, a noble metal such as platinum, gold, and silver, or a metal such as a cobalt chromium alloy or titanium is placed in the crucible 13, and a high-frequency oscillation coil 16 is energized to be turned on. Is heated and dissolved. At this time, the coil cooling water A is supplied to prevent the high-frequency oscillation coil 16 itself from being overheated and damaged.

On the other hand, the motor 22 is driven to drive the pulley 2
3. The mold mounting table 14 is rotated via the belt 24, the pulley 21, and the support shaft 20, and the mold 15 mounted thereon is rotated. In this case, the number of rotations varies depending on the type of metal used as the casting material and the shape of the mold, but is usually 50 to 50.
It is preferable that the rotation speed be higher in the range of 1000 rpm as the specific gravity of the metal used as the material is lower in this range. For example, in the case of platinum, 50 to 400 r
pm is preferable, and in the case of titanium, 500 to 100 r
ppm is preferred. Note that the rotation direction may be either clockwise or counterclockwise. Also, suction not shown
The pressure inside the chamber 12 is reduced by a tube.

After the material metal of the crucible 13 is melted, the handle 19 is operated from the outside of the chamber 12 to rotate the rotating shaft 18a.
a, 17b, the high-frequency oscillation coil 16, the crucible 13, and the rotating shaft 18b rotate, and the crucible 13 tilts. as a result,
The molten metal in the crucible 13 is moved to the mold 15
Is poured into the sprue 26.

Simultaneously with the completion of the injection of the molten metal into the mold 15, the pressurized gas B is introduced from the pressurized gas introduction pipe 25, and the inside of the chamber 12 is pressurized to perform casting. The degree of pressurization may be the same as in the case of normal pressure casting,
For example, it is preferable that the pressure in the chamber 12 be 2 to 4 atm.

The molten metal thus injected into the mold 15 passes through the runner 27 of the mold 15 and fills the cavity space 28 by the above-mentioned pressing force.
5 is rotated, so that the runner 27 is filled in order from the rotation delay direction without closing the runner 27 at one time. As a result, the air in the cavity space 28 easily escapes to the outside through the runner 27, thereby preventing nests and the like.

After completion of the casting, the inside of the chamber 12 is returned to normal pressure, the lid of the chamber 12 is opened, the mold 15 is taken out, and the mold 15 is crushed to obtain a casting. The obtained target casting is separated from a portion solidified by a runner or the like, and is polished to obtain a product.

[0031]

The mold is not limited to the one having the above-mentioned shape. For example, as shown in FIG. 5, a column-shaped space 33 extending vertically from the gate 32 and a plurality of branches extending from the column-shaped space 33. A mold 37 having a so-called tree-shaped inner space having a runner 35 composed of a branch space 34 and a cavity space 36 of a target casting provided at the tip of the branch space 34 of the runner 35. It may be.

In the case of this mold 37, in the conventional pressure casting method, when the cavity space 36 of the casting is provided in three or more upper and lower stages, insufficiency of casting and porosity often occur in the middle stage. According to the method (1), by using the pressing force and the centrifugal force together, the inflow of the molten metal is improved in all the stages, the burrs are eliminated, and the uniformity of the casting is obtained.

Test Example Using the casting apparatus shown in FIG. 1, a mold having a disk-shaped runner and six cavity spaces as shown in FIG. 2 was used as a mold. Rotation speed is 180r
pm, and the pressure in the chamber after the injection of the molten metal was set to 3 atm, to manufacture a platinum ring 30 having a deep V-shaped groove 31 as shown in FIG. The casting was repeated 18 times to produce 108 rings 6 × 18 times.

Each of the 108 rings thus cast had no nests in the deep V-shaped groove 31 and no sesame nests on the surface, and had a beautiful appearance.

[0036]

As described above, according to the present invention,
Since the molten metal of the metal melted in the crucible was poured into a rotating mold under reduced pressure and then cast under pressure,
Even when using a metal having a high melting point to produce a relatively small and complex shaped casting, nests are prevented from forming at the bottom of the groove and sesame nests on the surface. Retention can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view, partially cut away, showing an embodiment of a casting apparatus of the present invention.

FIG. 2 is a plan sectional view showing a mold used in the embodiment.

FIG. 3 is a side sectional view showing a mold used in the embodiment.

FIG. 4 is a perspective view showing an example of a ring cast by the method of the present invention.

FIG. 5 is a side sectional view showing another example of the mold used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Casting apparatus 12 Chamber 13 Crucible 14 Mold mounting table 15 Mold 16 High frequency oscillation coil 17a, 17b Support plate 18a, 18b Rotating shaft 19 Handle 22 Motor 24 Belt 25 Pressurized gas introduction pipe 26 Tap 27 Runner 27a Column-shaped space 27b Disk Shaped space 27c Branched space 28 Cavity space 32 Sluice 33 Columnar space 34 Branched space 35 Runner 36 Cavity space 37 Mold

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification symbol FI // A44C 27/00 A44C 27/00 A61C 13/20 A61C 13/20 C D B22D 25/02 B22D 25/02 G (58) Surveyed field (Int. Cl. ⁶ , DB name) B22D 13/00 B22D 13/06 B22D 13/10 B22D 25/02

Claims (6)

(57) [Claims] After injecting 1. A molten metal of the metal dissolved in the crucible to the mold, the cast casting method under pressure, the
A chamber capable of sealing the crucible and the mold with a lid
After the injection of the melt is completed, the molten metal is poured into the mold while the chamber is depressurized, and the mold is rotated around its central axis.
A casting method wherein a pressurized gas is introduced into the chamber to perform casting. 2. The mold according to claim 1, wherein the mold is a crushing mold, a sprue formed on an upper surface, a columnar space extending vertically from the sprue, a horizontally extending disc-shaped space communicating with a lower end of the columnar space, 2. The casting method according to claim 1, further comprising: a runner comprising a branch-like space extending radially from the disc-like space; and a cavity space of a target casting communicated with a tip of the branch-like space. . 3. The mold according to claim 1, wherein the mold is a crushing mold, and a runner including a sprue formed on an upper surface, a columnar space extending vertically from the sprue, and a branch-like space extending from the columnar space in a branch shape. The casting method according to claim 1, further comprising: a cavity space of a target casting communicated with a tip of the branch-like space. 4. A chamber openable and closable by a lid,
A pressurized gas introduction pipe and a suction pipe connected to this chamber, a crucible supported above the chamber so as to be tiltable by an external operation, and a metal disposed in the crucible are heated. Heating means for dissolving and melting, a mold mounting table disposed below the crucible, and a mold installed on the mold mounting table, when the crucible is tilted, the molten metal of the melted metal melts the mold In a casting apparatus in which the mold mounting table and the mold are arranged so as to be poured into a gate, a driving unit for rotating the mold mounting table around a central axis of the mold mounted thereon is provided. A casting device, which is provided. 5. The mold according to claim 1, wherein the mold is a crushing mold, a sprue formed on an upper surface, a columnar space extending vertically from the sprue, a horizontally extending disc-shaped space communicating with a lower end of the columnar space, The casting apparatus according to claim 4, further comprising: a runner comprising a branch-like space extending radially from the disk-like space; and a cavity space of a target casting communicated with a tip of the branch-like space. . 6. The mold according to claim 1, wherein the mold is a crush mold, and has a sprue formed on the upper surface, a column-shaped space extending vertically from the sprue, and a branch-shaped space extending in a branch shape from the column-shaped space. The casting apparatus according to claim 4, further comprising: a cavity space of a target casting which is communicated with a tip of the branch space.