JPS608897B2 - Casting method for titanium castings made of pure titanium or alloys whose main component is titanium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for casting titanium castings that enables casting of titanium casting materials made of pure titanium or alloys mainly composed of titanium with little or no oxidation. This is what we provide.

Titanium materials made of pure titanium or alloys with titanium as the main component have high heat resistance, excellent rice toughness, abrasion resistance, and insect resistance, are light, and have excellent physical and mechanical properties. It has far superior properties and has good wettability with the subject (a property that is compatible with the living body and does not become a living body even if it is surgically implanted into the living body), so it is used not only in the industry but also in dentures and the like. It is eagerly awaited that it will be used in the surgical medical field such as plastic surgery.

However, titanium material has extremely high activity and oxidizes rapidly even during cold forging, making it extremely difficult to process. It is only slightly processed.

For this reason, titanium products cannot be manufactured on an industrial basis for complex and elaborate shapes such as dentures, and even for simple and rough shapes, the productivity is extremely low and the processing cost is extremely high, making it extremely impractical. Inferior.

The inventor repeatedly conducted experiments in which titanium casting materials were cast into silica molds under an inert gas atmosphere using a dental casting machine, and found that despite maintaining an almost perfect inert gas atmosphere, The chitan castings that were cast had a high degree of oxidation and turned black, making them unusable for practical use.

We also considered various casting machines, but were unable to produce a practical titanium cast product.

Furthermore, after repeating experiments with castings made from various materials, it was found that titanium castings have a relatively low degree of oxidation and are superior in formability as molds. Although the results have been obtained, it is still far from practical.

As we made further improvements, we found that when titanium casting material was cast into a magnesia mold while keeping it at a certain low temperature, or when a small amount of titanium casting material was cast into a magnesia mold material, almost no oxidation occurred. No good titanium castings can be obtained.

As a result of investigating the cause, the following was discovered.

That is, oxides such as silica are suitable as materials that allow the mold to be easily made with high precision. However, titanium castings made using oxide molds are severely oxidized and are not practical.
The cause of oxidation is that the molten titanium casting material (melting point 1
66,800, standard coin temperature 1,800 to 190,000) had a very high activity and took away oxygen from the oxide mold, oxidizing the titanium casting material. This shows that in the temperature vs. oxide formation energy diagram in Figure 6, the diagram A or A for titanium and silica SjO or Si02
This was also supported by the relationship between diagrams C and 2 in the case of . Furthermore, from the relationship between diagram A or H for titanium and diagram H for magnesia, titanium casting materials are severely oxidized even in an atmosphere with a proper temperature of about 1900 to 2000oC. This confirms that Therefore, the applicant first molded a titanium casting mold using pure magnesia or a magnesia molding material containing magnesia as a main component, and when casting the titanium casting material, the titanium casting material in the mold was proposed a method of preventing oxidation of titanium casting materials due to oxygen in the mold materials by maintaining the temperature at
No. 35).

However, when the titanium casting mold is made of magnesia mold material, the following problems remain. In other words, the physical properties such as the hardness and strength of the mold and the coefficient of thermal expansion and air permeability, which have a large effect on the dimensional accuracy of the casting, are approximately fixed, so the above physical properties can be adjusted as appropriate depending on the purpose, size, shape, etc. of the titanium casting product. It becomes impossible to set. Moreover, magnesia mold material is a mold material that is not well known as a material for precision casting, so it is difficult for experts who are accustomed to conventional materials to use it, leading to a sense of anxiety. Moreover, since magnesia is a widely used mold material and is more expensive than silica or the like, the manufacturing cost of the mold becomes high.

In order to solve the above-mentioned problems, the present invention forms only the part of the wall of the titanium casting mold that contacts the titanium casting material with magnesia mold material, and the other parts are made of magnesia mold material. When the titanium casting material is melted and cast using an appropriately selected investment material such as inexpensive silica or zircon sand, is it possible to keep the titanium casting material in the titanium casting mold below a certain temperature from the beginning? By cooling the magnesia mold material quickly, the bond between the magnesium component and the oxygen component of the magnesia mold material is maintained stably, and while the molten titanium casting material solidifies and cools after being cast, oxygen in the magnesia mold material is taken away. To provide a casting method that allows a titanium cast product to be cast satisfactorily without being oxidized with little or no oxidation.

Next, an example of an automatic precision casting machine for carrying out the present invention and an example of the procedure for carrying out the present invention will be described in detail.

, The drawing shows an automatic precision casting machine, and the basic principle of its casting is as follows. That is, in the melting chamber 1, a high voltage is applied between the arc discharge electrode rod 2 and a predetermined cylindrical titanium casting material 3, an arc discharge 4 is generated there, and the titanium casting material 3 is melted. As shown in Fig. 4 A to 2, the titanium casting material 3 is collected in the crucible 5, which melts down from the top, and when it is completely melted to the bottom, the hole 6 in the bottom wall of the crucible 5 becomes solid. The material is no longer blocked at the bottom, and the melted material 3a passes through the tapping hole 6 and the through hole 7 under its own weight, and flows into the forming cavity 11 from the sprue 10 of the titanium casting mold 13 in the casting chamber 8. By keeping the melting chamber 1 and mirror chamber 8 in an inert gas atmosphere from before the titanium casting material 3 is melted to after it is poured, deterioration such as oxidation of the material is prevented.

In addition, an inert gas is passed from the melting chamber 1 at a differential pressure of about 4k9/c to the titanium casting mold 13 consisting of the conveying groove 12, the pouring hole 7, the sprue 10 in the mold 13, the modeling cavity 11, and the breathable investment medium. By continuing to flow through the rusting chamber 8', when the titanium casting material 3 is completely melted and flows into the mold 13, the melted material 3
After a is placed in an inert gas flow and smoothly flows deep into the molding cavity 11 of the mold 13, pressure is continued to be applied at a differential pressure of approximately 4k9/m to improve water circulation. The inert gas flow for this purpose is controlled as follows.

That is, when the start button 15 of the electric control device 14 is pressed, the vacuum pump 16 is started, and the melting chamber 1 is connected to the gas pipes 17, 20,
The casting chamber 8 is evacuated via the electromagnetic three-way valve 18 and the connector 19, and the casting chamber 8 is evacuated via the gas pipes 20, 21 and the strainer 22. When the degree of vacuum in the melting chamber 1 and the coin collecting chamber 8 reaches 70 Hg, the vacuum switch 23 is activated.
The valve element 18a of the electromagnetic three-way valve 18 is moved to the left, and the evacuation of the melting chamber 1 is stopped, and at the same time, inert gas such as argon is supplied from the cylinder 24 with the pressure setting valve 24A set at 3k9/c. Through gas pipes 17, 25 and electromagnetic three-way valve 18,
Maintained at 3 atmospheres. The mirror chamber 8 continues to be evacuated until the casting is completed.

When the melting chamber 1 reaches 0.5k9/c, the pressure switch 26 is activated to turn on the arc discharge power panel 27 of the melting device M, and the gap between the arc discharge electrode rod 2 and the titanium casting material 3 is turned on. I can wake up Ark 4. After the casting is completed, the electric control device 14 stops the operation of the vacuum pump 16 and the electromagnetic three-way valve 18, moves the valve body 18a to the right, and stops evacuation and inert gas injection. The gas is released into the atmosphere from the check valve 28 via the gas pipe 17, the electromagnetic three-way valve 18, and the connector 19, and a portion of the gas is drawn into the mirror compartment 8.As a result, the melting chamber 1 and the coin compartment 8 becomes atmospheric pressure and casting is completed.The titanium casting material 3 used is pure titanium or an alloy whose main component is titanium. In order to prevent oxidation of the titanium casting mold 13, pure magnesia or a magnesia mold material containing magnesia as a main component is used as the mold material for the portion 13A of the wall of the titanium casting mold 13 that comes into contact with the titanium casting material.In other words, as shown in FIG. As can be seen from the diagram of temperature versus oxide formation energy, at temperatures below about 170,000, the diagram tree of 2g○ is located below the diagram opening of 2riO, and pure magnesia (Mza0) is When formed, the energy for forming oxides of magnesium is smaller than the energy for forming oxides of titanium.That is, at temperatures below about 170,000, there is little or no bonding reaction between the oxidation in the magnesia mold material and the titanium casting material. This shows that it does not cause

However, the temperature of the port water when titanium casting material is poured is approximately 19
00 to 2000o0, the temperature is higher than the above temperature of 170000, and the oxidation reaction between the titanium casting material to be cast and oxygen in the mold 13 cannot be prevented. Therefore, as shown in FIG. 5, a portion 13A of the wall of the titanium casting mold 13 that comes into contact with the molten metal 3a of the titanium casting material 3, that is, a portion surrounding the modeling cavity 11, sprue 10, and scar hole 10a. is thinly formed using the magnesia mold material, and the other portion 13B is formed from a mold material different from the magnesia mold material.

At the same time, at least the part of the mold 13 that comes into contact with the molten metal 3a of the titanium casting material 3 is heated approximately 1,700 times from the beginning.
Either the temperature is maintained at a temperature of 0.00 or below, or the temperature is rapidly cooled.

In this embodiment, by reducing the mass of the titanium casting material 3 including the mirror and quickly cooling the molten metal 3a of the titanium casting material 3 with the large-mass mold 13 when making a change, the port water 3a
The temperature of the portion 13A in contact with is reliably maintained at about 1700 oo or less.

In addition, as the magnesia mold material containing magnesia as the main component, for example, 40% each of magnesia clinker M2 and M4 (components are shown in Table 1) manufactured by Nihon Kagaku Togyo Co., Ltd., which are commercially available for heat-resistant materials. , and 60% of the mixture, and 10% of zirconia or zircon sand as a particle size regulator is added to 90% of this mixture.

Table 1: Magnesia has a melting point of 11,000 points higher than silica.
0 is also a high-temperature heat-resistant material and has excellent high-temperature stability, so it has conventionally been used as a highly refractory cement for stamp materials in vacuum melting furnaces, back-up materials for brim, etc.

Here, the mold material for the part 13B of the wall of the mold 13 other than the part 13A that contacts the molten metal 3a of the titanium casting material 3 is one of silica, zircon sand, and aluminum, or any two of them. Mixtures of seeds or mixtures of these with magnesia can be used. When manufacturing the titanium casting mold 13 described above, magnesia mold material is dissolved in water, alcohol, or other binder to form a slurry, and this is applied to the surface of a wax pattern of a precision cast product such as a denture and dried. Magnesia coating about 1 to 2 skins thick. form.

The slurry of the above magnesia clinkers M2 and M4 is
It is suitable as a coating material because it has an appropriate viscosity, has a fast coating hardening rate, has good conformability to wax patterns, and does not generate cracks during drying.

A titanium casting mold 13 is manufactured by a conventional method using the coated wax pattern and the investment material such as the silica/zircon sand.

During casting, the titanium casting mold 13 is heated to a predetermined temperature using a heating device to expand, and then the molten metal 3a of the titanium casting material 3 is poured into the titanium casting mold 13 to solidify and solidify the titanium casting material after rusting. A method is possible that reduces the degree to which a titanium casting becomes smaller than a casting master due to shrinkage during cooling. Next, the structure of the automatic precision casting machine will be specifically explained.

That is, the reference numeral 29 is a casting machine body made of aluminum alloy or zinc alloy, in which the melting chamber 1 and the coin-collecting chamber 8 are separated by the partition wall 4.
2 is divided into upper and lower sections.

The front wall portion of the casting machine main body 29 is formed into a flange shape, and the operation port 31 of the melting chamber 1 and the operation port 32 of the mirror-containing chamber 8 are vertically aligned and closed. The titanium casting material 3 and the crucible 5 can be taken in and out of the melting chamber 1 through the operation port 31, and the mold body 9 consisting of the mold 13 and its cylindrical frame 47 can be taken out and put into the money-collecting chamber 8 through the operation port 32. Both operation ports 3
1 and 32 are opened and closed at the same time by a single door-type lid 33.

The lid is closed and locked by a locking mechanism 34 and hermetically sealed by O rings 35 and 36. That is, the lid 33 can be opened and closed with respect to the flange portion 30 using both the upper and lower hinges 37 at the right end as fulcrums, and the lid is locked at the intermediate height portion at the left end. The lid closing locking mechanism 34 is formed on the back surface of the flange portion 30 to lock a lever 38 pivotably supported on the lid 33 and a locking pawl 40 formed at the rear end of a shaft 39 of the lever 38. It consists of a locking receiving part 41. A mounting hole 67 is formed in the center of the partition wall 42, and a crucible holder 43 made of steel alloy such as golden gold or copper is removably fixed in a penetrating manner in the mounting hole 67, and a through hole is formed in the center of the crucible holder 43. 7 is dawning.

A crucible 5 is disposed in the melting chamber 1 and a mold body 9 is disposed in the money-collecting chamber 8, with the perforation hole 7 in between. In the center of the upper space of the melting chamber 1, the arc discharge electrode rod 2 of the melting device M is arranged to face the titanium casting material 3 placed on the crucible 5 from above. The crucible 5 is constructed as shown in FIG.

That is, the crucible body 44 is made of copper, a copper alloy containing copper as a main component, or a carbon material made of pure carbon or a substance containing carbon as a main component, and is formed into a short cylindrical shape. is formed. A receiving surface 46 for the cylindrical titanium casting material 3 is formed in the shape of an inverted cone on the central bottom surface of the material chamber 45, and an exit hole for the molten material is formed in the bottom wall of the crucible body 44 at the center of the material receiving surface 46. 6 is dawning. The tooth extraction hole 6 has an upper portion constricted with a conical surface and a lower portion formed with a cylindrical surface. The through hole 12 is cut out in the bottom surface of the crucible body 44 in a cross shape. The crucible 5 is formed to have a thick wall with a large mass relative to the volume of the material chamber 45, and when the titanium casting material 3 is melted in the large-mass copper material crucible 5, the titanium casting material 3 is melted. By quickly and widely diffusing the thermal energy transmitted from the molten metal 3a of No. 3 to the crucible 5 to each part of the wall of the crucible 5, the temperature of the portion of the titanium casting material 3 of the crucible 5 that comes into contact with the molten metal 3a increases. The speed is significantly reduced to finish pouring the port water 3a of the titanium casting material 3 from the crucible 5 into the titanium casting mold 13 before that part of the crucible 5 rises to the melting temperature.

Next, as shown in FIG. 2, one pole 27a of the output terminal of the arc discharge power supply panel 27 is connected to the arc discharge electrode rod 2,
The ten poles 27b are electrically connected to the casting material 3 in the crucible 5 through the crucible holder 43 and the crucible 5, which are connected to the casting machine main body 29.

The mold body 9 is made by arranging a wax pattern coated with the magnesia mold material in a cylindrical iron frame 47, and pouring into it a investing agent such as silica/zircon sand mixed with water and other binders. It was formed by condensing it and then condensing it in an electric furnace at about 80,000 ℃.

This mold 13 is porous and highly breathable, and has a sprue 10 in its upper part and a modeling cavity 11 in its lower part. The mold body 9 is placed on a mold holder 48, and by tightening the rotary operation smell 49, the spiral plate cam 5, which is a type of one-rotation cam, is formed.
0, it is pushed up via the support shaft 51 and the mold holder 48, and is brought into airtight contact with the mold receiving surface 53 on the lower surface of the peripheral wall of the through hole 7 of the holder 43 with the sealing tool 52 in between.

That is, a bracket 54 having an inverted L shape on the side is fixed to the bottom wall of the rusting chamber 8, a lifting guide hole 55 is vertically oriented in the upper wall of the bracket 54, and a pivot hole 56 is oriented longitudinally in the front wall of the bracket 54. It's dawning.

An intermediate portion of a camshaft 57 is rotatably supported in the pivot hole 56, and a rotational operation 49 is fixed to the front end thereof, and a spiral plate cam 50 is fixed to the rear end thereof by outer iron. The support shaft 5 is attached to the lifting guide hole 55.
1 passes through the metal fittings so as to be able to rise and fall freely, and the gap between the metal fittings is sealed with a circle ring 52. The upper end of the support shaft 51 fixedly supports the mold holder 48 in the coin compartment 8, and the lower end thereof is formed into a cam follower 58 having an arcuate surface and is in line contact with the cam 50. The cam follower 58 is prevented from rotating by coming into planar contact with a rotation prevention surface 59 on the back surface of the front wall portion of the bracket 54 so as to be able to move up and down. The support shaft 51 is pulled down and urged by a pull-down spring 60, and attached to both spring locking devices 61 and 62 protruding from the cam follower 58 and the bracket 54 behind the cam 50. be done. The mold pedestal 48 consists of upper and lower halves 63 and 64, with the upper halves 64 connected to the lower halves 63 with dowels 65.
It can be freely placed or removed concentrically by the iron connection between the hole 66 and the hole 66.

D-circular and cross-shaped ventilation grooves 68 are formed on the upper surface of each of the divided bodies 63 and 64. Incidentally, reference numeral 69 is a water hole, which is transparently installed in the flesh wall of the partition wall 42 in a manner that surrounds the pedestal 43.

The present invention is a method of casting a titanium casting material as described above using the automatic precision casting machine according to the embodiment described above, and the method ultimately involves the following steps. A portion 13A of the wall of the titanium casting mold 13 used for casting a titanium casting material 3 made of pure titanium or an alloy containing titanium as a main component, which contacts the titanium casting material, is made of pure magnesia or a material mainly composed of magnesia. The titanium casting material 3 is melted in an oxygen-free atmosphere in the crucible 5 of the casting machine. While maintaining an oxygen-free atmosphere, the molten metal 3a of the titanium casting material 3 is poured into the titanium casting mold 13 from the crucible 5, and the oxide generation energy of the titanium casting material 3 is converted into magnesium when magnesia is generated. At least the portion 13A of the titanium casting mold 13 that comes into contact with the titanium casting material 3 is held at a temperature higher than the oxide generation energy of The titanium casting material 3 cast into the titanium casting mold 13 contains most of the oxygen in the magnesia molding material 13 forming the part 13A of the wall of the titanium casting mold 13 that contacts the titanium casting material. This is a casting method that produces titanium castings with little or no oxidation by not allowing any bonding reactions.

Here, as a modification of the above method, a part thereof can be modified as follows. A In the case of the above example, an inert gas atmosphere of argon was used as the oxygen-free atmosphere, but instead of this, the inside of the melting chamber 1 and the coin collecting chamber 8 were evacuated,
It is also possible to melt and cast the titanium casting material 3 into the crucible 5 in a vacuum state.

B In order to prevent the temperature rise of the titanium casting mold 13,
Provide cooling means.

For example, it is also possible to form a coolant passage in the mold 13 to surround the modeling cavity 11 in the mold 13, and to cool the mold 13 by supplying cold soot such as cooling water to this cold soot passage.

The above cooling method is particularly effective when casting a relatively large cast product.

C The melting device M for melting the titanium casting material 3 is not limited to the arc melting devices 27 and 2, but can also be melted by a high frequency melting device that heats with high frequency.

Since the present invention has the above-described procedural configuration, it has the following effects.

1. Titanium castings made of pure titanium or alloys mainly composed of titanium can be cast with little or no oxidation.

This allows titanium products to be manufactured easily, efficiently, and accurately without impairing titanium's excellent physical and mechanical properties. 2. In the titanium casting mold used in the method of the present invention, only the part of the wall that contacts the titanium casting material is made of magnesia mold material, and the other part, which occupies most of the wall part, is made of any investment material. Therefore, it is possible to freely manufacture molds with optimal properties depending on the purpose, size, and shape of the cast product, and it is possible to cast titanium with desired properties.

3. Magnesia mold material is a highly refractory material that is widely used commercially as a filler for furnace walls, etc., so it is easy to obtain, but it is quite expensive.

However, in the mold used in the method of the present invention, only the surface layer of the wall that contacts the titanium casting material is made of magnesia mold material, and this surface layer is also coated with a slurry of magnesia mold material on the surface of the wax pattern. The sintering temperature is relatively low at 700 to 80,000, so it can be sintered in a conventional electric furnace.

Moreover, since most of the wall of the mold is formed from a conventional investment material, it can be easily formed by a skilled person using a conventional method.

Therefore, a titanium casting mold can be manufactured easily and at low cost, and a high quality titanium cast product can be manufactured at low cost.

[Brief explanation of the drawing]

1 to 5 show a casting machine etc. used for carrying out the present invention, FIG. 1 is a perspective view of the casting machine body, FIG. 2 is a vertical side view, and FIG. Figure 4 A to D are action diagrams from the start of melting to the start of casting, Figure 5 is an enlarged longitudinal cross-sectional side view of the mold body, Figure 6 is a view taken in the direction of arrow W in Figure 2, and Figure 7 is temperature vs. oxide. It is a diagram of generation energy. 1... Melting chamber, 2... Arc discharge electrode rod,
3... Titanium casting material (3a... Molten metal), 4... Arc discharge, 5... Crucible (45... Material container, 6... Hot water outlet), 1
...Through hole, 8...Cash collection room, 13...
...Titanium casting mold (13A...portion in contact with titanium casting material, 13B...portion other than the part in contact with titanium casting material), 29...casting machine body, 4
2... Compartment wall, M... Melting device. Figure 1 Figure 3 Figure 4 Figure 2 Figure 5 Figure 6 Completed diagram

Claims (1)

[Scope of Claims] 1. The part of the wall of the titanium casting mold used for casting a titanium casting material made of pure titanium or an alloy mainly composed of titanium, which comes into contact with the titanium casting material, is made of pure magnesia or magnesia. The titanium casting material is molded using a magnesia molding material whose main component is magnesia, and the other parts are formed using a molding material made of a substance different from the magnesia molding material. The molten titanium casting material is melted in a melting device and poured into a titanium casting mold from a crucible while maintaining an oxygen-free atmosphere.
At a temperature at which the oxide formation energy of the titanium casting material is larger than the oxide formation energy of magnesium when magnesia is generated, at least the wall of the titanium casting mold made of the magnesia molding material is made of titanium casting material. Either hold the contacting part from the beginning or cool it quickly, so that the titanium casting material cast into the titanium casting mold forms the part of the wall of the titanium casting mold that comes into contact with the titanium casting material. The main component is pure titanium or titanium, which is characterized by producing titanium castings with little or no oxidation by causing little or no bonding reaction with oxygen in the magnesia mold material. A method for casting titanium castings made of an alloy. 2. In the method for casting a titanium casting product described in claim 1, when the mass of the titanium casting material to be cast is reduced and this small mass of the titanium casting material is cast into the titanium casting mold, By rapidly cooling the mold, the part of the wall of the titanium casting mold that comes into contact with the titanium casting material is transferred to the oxide formation energy of the titanium casting material, which produces magnesium oxide when magnesia is formed. A method of maintaining the temperature at a value greater than the energy. 3. In the method for casting a titanium casting product as set forth in claim 1 or 2, at least when the molten titanium casting material is poured into the titanium casting mold, the part of the wall of the titanium casting mold is A method in which the parts that come into contact with titanium casting materials are cooled using cooling means. 4. In the method for casting titanium castings as set forth in claim 3, a refrigerant passage is formed within the wall of the titanium casting mold, and the refrigerant passing through the refrigerant passage is used to cool the wall of the titanium casting mold. A method of cooling parts that come into contact with titanium casting materials. 5 Any one of claims 1 to 4
In the method for casting tan castings described in Section 1, an inert gas atmosphere is used as an oxygen-free atmosphere in the place where the titanium casting material is melted and cast. 6 Any one of claims 1 to 4
In the method for casting titanium castings described in 2. above, a vacuum atmosphere is used as an oxygen-free atmosphere in the place where the titanium casting material is melted and cast. 7 Any one of claims 1 to 6
In the method for casting a titanium casting product described in 1., a method using a titanium casting mold in which the wall of the titanium casting mold other than the part that comes into contact with the titanium casting material is formed of a molding material made of silica. 8 Any one of claims 1 to 6
In the method for casting a titanium casting product described in 1., a method using a titanium casting mold in which the wall of the titanium casting mold other than the part that comes into contact with the titanium casting material is made of a molding material made of zircon sand. . 9 Any one of claims 1 to 6
In the method for casting a titanium casting product described in 1., a method using a titanium casting mold in which the wall of the titanium casting mold other than the part that comes into contact with the titanium casting material is formed of a molding material made of alumina. 10 In the method for casting a titanium casting product as set forth in any one of claims 1 to 6, the portion of the wall of the titanium casting mold other than the portion that comes into contact with the titanium casting material. A method using a titanium casting mold made of a mold material consisting of a mixture of any two of silica, zircon sand, and alumina. 11. In the method for casting a titanium casting product as set forth in any one of claims 1 to 6, a portion of the wall of the titanium casting mold other than the portion that comes into contact with the titanium casting material. A method using a titanium casting mold made of a mold material made of a mixture of magnesia and one of silica, zircon sand, and alumina. 12. In the method for casting a titanium cast product as set forth in any one of claims 1 to 6, the portion of the wall of the titanium casting mold other than the portion that comes into contact with the titanium casting material. A method using a titanium casting mold made of a mold material consisting of a mixture of any two of silica, zircon sand, and alumina and a mixture of magnesia. 13. In the method for casting a titanium cast product according to any one of claims 1 to 12, the crucible is made of a copper material made of pure copper or an alloy whose main component is steel, and the material container is made of copper material. When a titanium casting material is melted in a large-mass copper crucible, the thermal energy transferred to the crucible made of the molten titanium casting material is By quickly and widely dispersing the large mass of copper material into each part of the wall of the crucible, the rate of temperature rise in the part of the crucible that comes into contact with the titanium casting material is significantly reduced, and the crucible part reaches the melting temperature. A method in which the molten titanium casting material is poured from the crucible into the titanium casting mold before the titanium casting material rises to the top. 14. In the method for casting a titanium cast product according to any one of claims 1 to 12, the crucible is made of pure carbon or a carbon material made of a substance mainly composed of carbon, A method of melting titanium casting material in this carbon material crucible.