JPH0244925Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" The invention relates to a relatively small precision casting machine, and is used to manufacture precision castings for dental use, such as titanium and titanium alloys, which have extremely high high temperature activity. This relates to a crucible for dissolving titanium.

"Prior Art" Recently, titanium and titanium alloys, which have excellent compatibility with living organisms and corrosion resistance, and have low specific gravity, have been used as dental materials and plastic surgery materials. As a conventional crucible of this type for melting dental materials such as titanium alloys, the one shown in FIG. 5 is known.

Reference numeral 1 in the figure is a precision casting machine, and this precision casting machine 1 is made up of a closed container 1a with a door-type lid 1b attached to the side surface, and the inside of the closed container 1a is a pressurized melting chamber 2 in the upper part. and a vacuum casting chamber 3 at the bottom. On the ceiling of the pressurized dissolution chamber 2, the tip is exposed inside the pressurized dissolution chamber 2, and
A non-consumable electrode 2b whose base end is connected to a power supply terminal 2a is fixed, and a communication hole 5 is formed in the partition wall 4 that partitions the pressurized melting chamber 2 and the reduced pressure casting chamber 3. A ring-shaped bulge 6 is formed on the periphery of the pressurized melting chamber 5 (upper side), which serves as a pedestal for the crucible 7 placed on top of the ring-shaped bulge 6. A link-shaped bulge 8 formed at the periphery of the communication hole 5 on the casting chamber 3 side (lower side)
is a contact portion of the mold 9 placed below it. In addition, a lid 1 is placed on the side of the pressurized dissolution chamber 2.
A viewing window 2c is provided at b, allowing the inside to be viewed visually.

The crucible 7 is a short cylindrical copper container,
The inside is formed into a mortar shape, and a circular outflow hole 7a is formed in the center of the bottom. A cylindrical casting material 7b made of an alloy and having a diameter larger than the diameter of the outflow hole 7a is placed inside the crucible 7, and the outflow hole 7a is formed on the bottom surface of the casting material 7b. It has become blocked. The mold 9 is a cylindrical mold 10 in which a breathable embedding material 11 is cast.
A sprue 12 and a modeling cavity 13 are formed in the casing.

A mold pedestal 14 is provided at the bottom of the mold 9, and by turning a handle 15, this pedestal 14 can be moved up and down with a circumferential cam type jack 16 via a rod 17. By tightening the handle 15, the mold 9 is moved upward to bring the mold 9 into airtight contact with the bulge 8. Furthermore, the power supply terminal 2a and the bottom of the vacuum casting chamber 3 are connected by a power supply 18.
A pipe 20 for supplying argon gas from an argon gas cylinder 19 is connected to the pressurized melting chamber 2, and a vacuum pump 21 for evacuating the inside is connected to the reduced pressure casting chamber 3 via a pipe 22. is,
The pipe 22 is connected to the pipe 20 via a three-way valve 23 and a pipe 24.

Then, open the lid 1b of the precision casting machine 1,
The casting material 7b is placed inside the crucible 7 of the pressurized melting chamber 2 so as to cover the outflow hole 7a, and the mold 9 is set at a predetermined position inside the vacuum casting machine 3, after which the lid 1b is closed. Next, the vacuum pump 21 removes air from the pressurized melting chamber 2 and the reduced pressure casting chamber 3 to create a vacuum inside the chamber, and then the three-way valve 2
3 and enter argon gas 1 into pressurized melting chamber 2.
9 is supplied to create an argon gas atmosphere in the chamber, and a constant pressure difference is provided between the pressurized melting chamber 2 and the reduced pressure casting chamber 3. Then, by applying electricity to the non-consumable electrode 2b, an arc is generated between the non-consumable electrode 2b and the casting material 7b, and the casting material 7b is melted from above. When the casting material 7b melts to the bottom, the casting material 7b naturally falls from the outflow hole 7a of the crucible 7 due to the pressure difference between the pressurized melting chamber 2 and the reduced pressure casting chamber 3 and its own weight, and enters the forming cavity of the mold. It's becoming more and more popular.

``Problems to be solved by the invention'' However, in the conventional crucible for melting titanium, when the casting material is poured into the mold, at the same time as the casting material is melted in the crucible, a Since it is designed to naturally fall from a circular outflow hole to the sprue of the mold, it is impossible to control the melting temperature of the material, and the melted material from the low temperature side that is in contact with the crucible flows first into the mold. In addition, when an arc is generated to melt the material, the material does not melt uniformly from the top to the bottom. Occasionally, cases occur where melting occurs unevenly, and in such cases, the partially melted material falls first through the outflow hole of the crucible, leaving a considerable amount of material inside the crucible. There were problems such as the phenomenon occurring.

The present invention has been developed in view of the above-mentioned problems, and it is possible to quickly melt the casting material on the crucible to the optimum casting temperature state, and also to reduce the melting temperature on the low-temperature side that is in contact with the crucible. Titanium melting allows the melted material on the high-temperature side near the arc to drop into the sprue of the mold instantaneously, and can be poured without lowering the casting temperature during casting. The purpose is to provide a crucible for use.

"Means for solving the problem" The present invention forms a step-like recess on the upper surface of the crucible so that the volume is smaller than the casting material, and forms a pouring port adjacent to the recess on one side of the crucible. death,
Further, the crucible is supported by a support pin so that one side of the crucible is tilted by the crucible's own weight, and the crucible is held in a horizontal state by a detachable locking means. By configuring the system as follows, the above problem is solved.

"Operation" In this invention, the casting material rises to the top of the crucible due to surface tension on the concave part of the crucible, which is formed to have a smaller volume than the casting material, so that the optimum casting temperature is achieved. It will be dissolved. In this state, when the locking means is released from the crucible and the crucible is tilted by its own weight around the support pin toward one side where the pouring spout is formed, the molten casting material in the crucible is quickly released from the pouring spout. and is poured into the mold. At this time, the cast metal in the crucible will fall into the mold from the highest temperature upper layer, and will fall last to the lower temperature molten metal that is in contact with the crucible. Also,
Since the recess is formed to have a smaller volume than the casting material and the crucible is tilted, a large amount of molten metal does not remain inside the crucible. Furthermore, since the recess and the pouring hole are adjacent, the casting material does not come into contact with new surfaces of the crucible, and the temperature of the casting material does not drop.

"Example" The present invention will be described below with reference to the drawings.
1 to 4 show an embodiment of the crucible for dissolving titanium of the present invention. In these figures, the same elements as those shown in the prior art are designated by the same reference numerals, and the explanation thereof will be omitted.

First, a precision casting machine using the crucible of the present invention will be explained with reference to FIG. Reference numeral 1 in the figure is a precision casting machine, and this precision casting machine 1 constitutes a closed container with a pressurized melting chamber 2 in the upper part and a reduced pressure casting chamber 3 in the lower part. The pressurized melting chamber 2 has a substantially hemispherical upper portion, a flange 2f at the lower edge, and a non-consumable electrode 2b attached to the ceiling. The vacuum casting chamber 3 is a container formed in a cylindrical shape with a bottom, and a partition wall 4 is fixed to the upper part of the vacuum casting chamber 3 to partition it from the pressurized melting chamber 2, and the outer peripheral end of the partition wall 4 is connected to the flange 2f. It constitutes a flange 4f that is abutted. The pressurized melting chamber 2 and the vacuum casting chamber 3 are connected to each other via a hinge (not shown) so that they can be opened and closed.
With the vacuum casting chamber 3 and the vacuum casting chamber 3 closed, the flange 2f
and 4f are sealed by an O-ring 31.

A through hole 5 is formed in the partition wall 4,
The peripheral edge of the through hole 5 protrudes toward the reduced pressure casting chamber 3,
A cylindrical body having an inverted conical space formed therein is fixed, thereby forming a housing portion 4a for the mold 9. The mold 9 is formed by casting an air-permeable embedding material 11 into an inverted conical shape so as to fit into the internal space of the storage section 4a, and the embedding material 11 has a sprue 12 and a modeling cavity. 13 are formed.

A crucible 7 of the present invention, which is a container for melting a casting material 7b such as titanium or a titanium alloy, is disposed above the partition wall 4.

As shown in FIGS. 1 and 2, the crucible 7 is made of copper, which has high thermal conductivity, and is formed into a rectangular parallelepiped so as not to react with the casting material 7b, which is highly active at high temperatures such as titanium. On the upper surface side, the recess 7j is formed by forming three step-like concentric cylindrical spaces whose diameter becomes smaller and deeper from the outside. A pouring hole 7m for pouring the melted casting material 7b is formed on the front side (one side side) of the crucible 7, and the pouring hole 7m has a cross section formed so as to approach the edge of the recess 7j. It is constituted by a semicircular notch 7k. Further, the volume of the recess 7j is less than half that of the casting material 7b placed on top of the recess 7j and melted. The casting material 7b has a spherical upper part and a bottom part so as to be stably placed in the uppermost recess 7j. Furthermore, the crucible 7 is arranged such that the pouring port 7m is located above the sprue 7m of the mold 9 (see Fig. 3), and the crucible 7 is located on the opposite side to the pouring port 7m (front side) formed in the crucible 7. Support pins 7n for supporting the crucible are fixed horizontally to both sides of the crucible 7, which are separated from each other so as to be tilted toward the spout 7m due to their own weight. The support pin 7n is rotatably supported by a copper crucible support frame 7o that is erected in parallel on both sides of the crucible 7 within a U groove 7p formed in the upper part of the crucible support frame 7o. Furthermore, the support frame 7o is
It is fixed to the upper part of the partition wall 4 via a crucible stand 7q. The crucible stand 7q is formed in a box shape (or may be cylindrical), and an opening 7r is formed in the upper ceiling plate so as not to interfere with the rotation of the crucible. An inlet 7s and an outlet 7t of circulating water for cooling are attached, and the cooling water that enters from the inlet 7s is
The liquid is discharged from the discharge port 7t through a tube 7u arranged in a predetermined shape inside the crucible stand 7q.

Further, the crucible 7 is provided with a locking means 7v for holding the crucible 7 in a horizontal state so that the casting material 7a does not flow out from the crucible when the casting material 7a is melted. Locking means 7v
As shown in FIG. 1, there is a holding pin 7w horizontally fixed to the back surface of the crucible 7 (on the side opposite to the pouring port 7m), and a hook 7x for locking the upper surface of the free end of the holding pin 7w. The rotary solenoid 7y is fixed to the partition wall 4 with its head protruding into the pressurizing chamber.

Next, the operation of the precision casting machine of this embodiment configured as described above will be explained along with its usage method.

First, the pressurized melting chamber 2 is opened, and the mold 9 is stored in the storage part 4a of the mold 9, and the casting material 7b is placed on the recess 7j of the crucible 7 held horizontally. As shown, the pressurized melting chamber 2 is closed and the flanges 2f and 4f are brought into close contact. and,
By removing the air inside the precision casting machine 1, the inside of the precision casting machine 1 is made into a vacuum, and then an inert gas such as argon gas is injected into the pressurized melting chamber 2 side to pressurize it to a predetermined pressure.
The casting material 7b is placed in the crucible 7 by creating a predetermined pressure difference between the pressurized melting chamber 2 and the reduced pressure casting chamber 3 and at the same time generating an arc between the non-consumable electrode 2b and the casting material 7b. It is melted on the recess 7j.

When the casting material 7b is melted on the recess 7j of the crucible 7, which has a smaller volume than the casting material, the casting material remains bulged in a spherical shape at the top of the crucible recess 7j due to surface tension. be done. When the casting material reaches the optimum casting temperature,
Activate rotary solenoid 7y and hook 7
By rotating x, the holding pin 7w fixed to the back of the crucible 7 is removed from the hook 7x, and as shown in FIG. 4, the crucible 7 is tilted toward the spout 7m due to its own weight. When the crucible 7 is tilted, the casting material that has risen on the concave portion 7j of the crucible 7 due to surface tension flows from the concave groove 7l of the pouring port 7m into the mold 9.
After flowing into the sprue 12, it is cast into the modeling cavity 13. At this time, the melted casting material 7b in the crucible 7 quickly falls from the upper layer where the temperature is higher into the mold 9, and the lower the temperature of the casting material in contact with the crucible 7, the last to fall. Or, it may solidify and remain inside the recess 7j of the crucible 7 without falling. However, since the crucible is tilted and the recess 7j is shallow, almost no molten metal remains in the recess 7j of the crucible, and most of the casting material melted above the recess 7j is reliably poured. The Rukoto.

Therefore, in the titanium melting crucible of this embodiment, the casting material 7b is once placed in the recess 7 of the crucible 7.
After being melted on top of j, the crucible 7 is tilted and poured into the mold 9 from the pouring port 7m, so that the casting material can be sufficiently melted and the melting temperature of the material can be kept low. This makes it possible to control the appropriate casting temperature (melting temperature + 50℃) even for casting materials such as alloys that have a wide range of melting temperatures.
~100℃). Therefore, unlike conventional methods, the phenomenon in which the casting material melts unevenly and the partially melted material falls first, leaving a considerable amount of material inside the crucible, does not occur. It becomes possible to efficiently use most of the melted casting material.

Further, the crucible 7 and the support frame 7o are made of copper with high thermal conductivity, and the inside of the crucible stand 7q is cooled with circulating water, thereby indirectly cooling the crucible 7 via the crucible support frame. Since the heat generated when melting the casting material 7b is taken away from the crucible 7, the crucible 7 is not overcooled, and the crucible 7 is not overcooled, and the melting temperature is high enough to prevent the melting of titanium, titanium alloys, etc., which are highly active at high temperatures. It does not react with the casting material, and the shape of the crucible 7 can be made smaller.

Furthermore, since the concave portion 7j of the crucible 7 is formed in a step-like manner, the contact area between the surface of the crucible and the casting material is reduced, and the thermal conductivity of the casting material 7b from the crucible to the crucible 7 is reduced accordingly. The material 7b can be melted efficiently and quickly, and the temperature rise in the crucible can be suppressed.
Further, since the recess 7j and the pouring port 7m are formed very close to each other, even if the crucible is tilted and poured into the mold, the casting material will not come into contact with a new surface of the crucible during pouring. It can be cast at the optimum temperature.

Note that technical matters other than those described above or other embodiments will be described below.

(i) In the above embodiments, titanium and titanium alloys were used as the casting materials, but the present invention is not limited to this, and may be applied to cases where the casting materials are other noble metal alloys, non-precious metal alloys, etc. Of course.

(ii) In the above embodiment, the crucible locking means is a holding pin 7w fixed to the back surface of the crucible 7.
, a hook 7x for locking the hook 7x, and a rotary solenoid 7y for rotating the hook 7x. Any method is fine. for example,
The rotary solenoid may be operated manually.

(iii) The concave portion 7j of the present invention has three concentric cylindrical spaces.
Although the shape is formed into a step-like shape, the shape is not limited to this, and as long as the recess has a shape that reduces the contact surface between the crucible and the casting material, 2.
Of course, the design can be changed to a step, four steps, or other shapes as appropriate.

"Effects of the Invention" As explained in detail above, the crucible for melting titanium of the present invention has a concave portion with a volume smaller than that of the casting material on the upper surface side of the crucible, so that the casting material can reach the surface above the concave portion of the crucible. Due to the tension, the melt rises to the top of the crucible and is melted at the optimum melting temperature. Furthermore, since the crucible is supported by support pins and held in a horizontal position by detachable locking means, the locking means can be released from the crucible to allow the crucible to move under its own weight. When the crucible is tilted toward the pouring port with the support pin as an axis, the casting material melted on the concave portion of the crucible quickly flows out of the pouring port and is cast into the inside of the mold. At this time, since the recess and the pouring hole are formed close to each other, the molten casting material does not come into contact with the new surface of the crucible during pouring into the mold, and is cast at the optimum temperature. becomes. Furthermore, since the recesses of the crucible are formed in a step-like manner, the contact area between the surface of the crucible and the casting material is reduced, which reduces the thermal conductivity from the casting material to the crucible, making the casting material more efficient. In addition, it is possible to quickly melt the melt, and it also has the effect of suppressing the temperature rise in the crucible.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a perspective view of the crucible and its surroundings disposed above the partition wall, and FIG. 2 is a perspective view of the crucible shown in FIG. 1. 3 is a side sectional view of a precision casting machine using the crucible of the present invention, and FIG. 4 is an explanatory diagram to explain how the melted casting material inside is poured into the mold by tilting the crucible. , FIG. 5 is a side sectional view of a conventional crucible disposed inside a precision casting machine. 1...Precision casting machine, 2...Pressure melting chamber, 2b...
...Non-consumable electrode, 3... Vacuum casting chamber, 4... Partition wall, 5... Communication hole, 7... Crucible (titanium melting crucible) 7b... Casting material, 7j... Recess, 7m
...Pouring spout, 7n...Support pin, 7v...Locking means, 7w...Holding pin, 7x...Hook, 9...
Mold, 12... sprue.

Claims (1)

[Scope of utility model registration request] A titanium titanium alloy provided inside a pressurized melting chamber in the upper part of the vacuum casting chamber, and arranged such that the pouring port is located above the sprue of the mold provided between the vacuum casting chamber and the pressurized melting chamber. The crucible is a melting crucible, wherein a step-like recess is formed on the upper surface side of the crucible so as to have a smaller volume than the casting material, and a pouring port adjacent to the recess is formed on one side of the crucible. The crucible is supported by support pins so that one side of the crucible is tilted by its own weight, and the crucible is held in a horizontal state by detachable locking means. Characteristic crucible for dissolving titanium.