JPH0531571A - Method and apparatus for manufacturing casting - Google Patents

Abstract

PURPOSE:To produce a casting having little influence to solidified shrinkage at center part and excellent internal quality without any contamination and entrapment of gas. CONSTITUTION:In casting, molten metal 16 poured into a water-cooled copper- made mold 3 is heated by induction-heating with an induction heating coil 11, and after eliminating bubbles of gas, etc., by partially delaying solidification of the molten metal 16 with the above induction-heating, the induction-heating is stopped and the molten metal is solidified in the above mold 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to ordinary metals and alloys such as iron and aluminum, especially titanium,
The present invention relates to a casting method and a casting apparatus used for casting a simple substance or an alloy of a refractory metal such as tungsten or molybdenum or an active metal.

[0002]

2. Description of the Related Art A refractory metal or active metal composed of a simple substance such as titanium, tungsten, molybdenum or an alloy thereof has a high melting point and is active. Therefore, special caution is required as compared with ordinary metal casting. There are many.

That is, melting without contamination in a controlled atmosphere (vacuum or inert gas atmosphere), no contamination from a molten metal container (crucible, etc.) and mold, and no inclusion of bubbles during casting, It is necessary to pay attention to such matters.

[0004]

However, when melting and casting are performed using a refractory crucible or a mold, there is a problem that the crucible refractory or the mold material may be contaminated. There is a problem that many undissolved parts occur in skull melting with less pollution, and when casting by vacuum suction through a breathable mold, there is a problem that gas in the melting chamber may be involved. In addition, there is a problem that the solid gravity shrinkage of the central portion may occur in simple gravity casting, and it has been a problem to solve these problems as much as possible.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. It is free from contamination by the atmosphere of molten metal and from the crucible refractory or mold material, and the influence of gas entrainment during casting. It is an object of the present invention to make it possible to manufacture a casting having excellent internal quality by avoiding the above-mentioned problem as much as possible and reducing the influence of solidification shrinkage of the central portion.

[0006]

A method for manufacturing a casting according to the present invention is a method for heating a molten metal poured from a molten metal container into a water-cooled copper mold by induction heating to partially solidify the molten metal by the induction heating. It is characterized in that it is configured to be a casting having excellent internal quality by solidifying in the water-cooled copper mold by stopping induction heating after eliminating bubbles such as gas, and is adopted as necessary. In another embodiment, the melting atmosphere and the casting atmosphere are controlled atmospheres such as inert gas and vacuum, and in the same embodiment, the molten metal poured from the molten metal container into the water-cooled copper mold is introduced. The heating is performed by heating, the solidification of the molten metal is delayed on the upper side by the induction heating, the bubbles such as gas are floated, and then the induction heating is stopped. Is characterized in that the molten metal poured into the water-cooled copper mold is configured to directionally solidify by sequentially stopping induction heating from the lower side to the upper side and sequentially shifting the solidification site upward. I am trying.

Further, the casting manufacturing apparatus according to the present invention is
A water-cooled copper mold in which molten metal is poured from a molten metal container, and induction heating that heats the molten metal in the water-cooled copper mold by induction heating to partially delay the solidification of the molten metal and eliminate bubbles such as gas In the embodiment adopted as needed, the induction heating means is composed of a single induction heating coil and is movable in the upper direction. In the same embodiment, the induction heating means is composed of a plurality of induction heating coils arranged in the longitudinal direction, and the power is cut off sequentially from the lower induction heating coil to the upper induction heating coil. Is possible,
The structure is such that the solidification of the molten metal is delayed on the upper side, and in the same manner, in the embodiment, the water-cooled copper mold is composed of divided segments that allow the removal of the casting, and in the same embodiment, the water-cooled copper mold is the divided segment. In the same embodiment, the molten metal container is a water-cooled copper melting furnace capable of tilting, a water-cooling copper melting furnace capable of tapping the bottom, a plasma heat source cold hearth, The present invention is characterized in that the structure is selected from an arc heat source cold hearth and an electron beam heat source cold hearth, and the structure of the invention relating to the above-mentioned casting manufacturing method and manufacturing apparatus serves as means for solving the above-mentioned conventional problems.

[0008]

Since the casting manufacturing method and the casting apparatus according to the present invention have the above-mentioned structure, the adjusted atmosphere (vacuum or inert gas atmosphere, etc.) against contamination from the atmosphere is provided. ) Melting and casting can be dealt with. To prevent contamination from the molten metal container (melting furnace, crucible, etc.) and mold, use a water-cooled copper melting furnace (crucible) or water-cooling for the molten metal container and mold. It can be dealt with by enabling non-contact melting and heating using a copper mold, and to prevent air bubbles from being entrained during casting, it is necessary to use a water-cooled copper mold equipped with induction heating means for melting metal. It can be dealt with by eliminating the bubbles such as gas by partially delaying coagulation or directional coagulation, and induction heating means against the influence of coagulation contraction in the central part. According the heating control becomes as it can cope by or to perform the partially slow down directional solidification coagulation, superior castings internal quality by these is to be produced.

[0009]

FIG. 1 and FIG. 2 show an embodiment of a casting manufacturing apparatus used for carrying out the casting manufacturing method according to the present invention. A water-cooled copper mold 3 is provided inside the insulating sleeve 2.

The water-cooled copper mold 3 has a casting space 4 in the center thereof, and in this embodiment, it is in the shape of a connecting rod rough material for an engine, and a portion corresponding to a small end is a lower portion. The part corresponding to the side and the large end is located on the upper side.

As shown in FIG. 2, the water-cooled copper mold 3 is composed of eight water-cooled copper split segments 3a to 3h each having a fan-shaped horizontal cross section inside the insulating sleeve 2. A cooling water passage 5 is provided inside each of 3a to 3h, and a cooling water inlet 7 and a cooling water outlet 8 are provided in the cooling water passage 5.

Further, each water-cooled copper split segment 3a-3
A ceramic sprayed film 9 for electrical insulation is provided on each divided surface of h.
Are formed, and each water-cooled copper segment 3a to 3 is formed.
h is electrically insulated from each other and can be divided into two by water-cooled copper split segments 3a and 3h and 3d and 3e so that the casting can be taken out after casting. Has become.

On the other hand, on the outside of the insulating sleeve 2, an induction heating coil 11 which is an induction heating means is provided so as to be able to move up and down, and the induction heating coil 11 is also provided with a cooling water passage (not shown) to enable water cooling. Has become.

Further, a protective cylinder 13 is provided on the upper end of the water-cooled copper mold 3 via a seal ring 12, and an Ar gas supply pipe 14 is inserted into the protective cylinder 13.

Therefore, when a relatively large connecting rod coarse material for an engine having a product weight of 2 kg is manufactured using the casting manufacturing apparatus 1 having such a structure, the material is T.
i-6Al-4V alloy was used.

Then, the induction heating coil 11 was lowered to the position shown by the phantom line in FIG. 1 for energization, and Ar gas was supplied from the Ar gas supply pipe 14 to make the interior of the mold an inert atmosphere.

Then, the molten metal of the Ti alloy was poured to almost fill the casting space 4, and the molten metal 16 was heated by induction heating.

In heating the molten metal 16 at this time, a so-called cold crucible revitation heat using a water-cooled copper mold 3 in which the water-cooled copper divided segments 3a to 3h are insulated by a ceramic sprayed film 9 for electric insulation is used. Since high-frequency induction heating is performed by the induction heating coil 11, an eddy current is formed in the inner peripheral portion of the water-cooled copper mold 3 (a portion near the casting space 4), and this eddy current causes a skin current in the molten metal 16. And the molten metal 16 is heated.

On the surfaces of the water-cooled copper mold 3 and the molten metal 16, due to the repulsive force of the electric currents whose phases are opposite to each other, the molten metal 16 is slightly separated from the wall surface of the water-cooled copper mold 3 to form a gap. .

Therefore, since the heat transfer from the molten metal 16 to the water-cooled copper mold 3 is suppressed by the formation of the gap, the molten metal 16 is maintained at a high temperature and is not in contact with the water-cooled copper mold 3. Contamination from the mold 3 hardly occurs.

Thus, when the induction heating coil 11 is gently moved in the upper direction after the induction heating for the required time has elapsed, the induction heating for the molten metal 16 in the lower position of the casting space 4 is not reduced or stopped. The molten metal 16 adheres to the wall surface of the mold and is cooled by the water-cooled copper mold 3 to start solidification rapidly. As the induction heating coil 11 is raised, the solidified portion gradually rises to cause directional solidification. The induction heating by stopping the power supply after moving the
The molten metal 16 at the position corresponding to the large end is brought into contact with the mold wall surface to rapidly solidify.

Thereafter, the casting is taken out by dividing the water-cooled copper mold 3 into two.

The engine connecting rod rough-molded product, which is a casting thus obtained, is directionally solidified from the small end side toward the large end side, and is excellent in internal quality. It was

FIG. 3 shows an embodiment in which molten metal 16 is poured into the casting space 4 of the water-cooled copper mold 3 of the casting manufacturing apparatus 1, and in this embodiment, a molten metal container is used. The case where a water-cooled copper melting furnace (crucible) 21 that can be tilted is used is shown.

When the molten metal 16 is melted by using such a water-cooled copper melting furnace 21, the melting atmosphere is controlled so that contamination from the melting atmosphere is eliminated and the molten metal 16 is melted.
Is melted by so-called cold crucible levitation melting, so there is no contamination from the mold, and because it is possible to electromagnetically stir the molten metal 16 by cold crucible, it is possible to obtain a uniform molten metal temperature and composition. Since it can be obtained, the use of scrap or the like is acceptable, which is advantageous for reducing the melting cost.

FIG. 4 shows another embodiment in which the molten metal 16 is poured into the casting space 4 of the casting manufacturing apparatus 1 shown in FIG. 1. In this embodiment, a molten metal container is used. It shows a case where a water-cooled copper melting furnace (crucible) 31 capable of discharging molten metal 16 from the furnace bottom is used.

That is, the water-cooled copper melting furnace 31 has a water-cooled copper crucible 33 inside an insulating sleeve 32.
This water-cooled copper crucible 33 has a melting space 34 in its central portion.
And has a molten metal outlet 35 on the bottom side and is composed of circumferentially divided water-cooled copper split segments, and a cooling water passage 36 is provided inside each water-cooled copper split segment. In addition, an insulator 39 is provided on the division surface of each water-cooled copper division segment so as to be electrically insulated from each other.

An induction heating coil 37 is provided up and down outside the water-cooled copper crucible 33.

Therefore, when the base metal is melted using such a water-cooled copper melting furnace 31, the induction heating coil 37 is set to the raised position and the induction heating coil 37 is energized to move the water-cooled copper crucible 33. Cold crucible levitation melting is performed on the base metal charged in the melting space 34.

Also in this case, the molten metal 16 is slightly separated from the wall surface of the water-cooled copper crucible 33 by the repulsive force of the electric currents whose phases are opposite to each other on the surfaces of the water-cooled copper crucible 33 and the molten metal 16. , The temperature of the molten metal 16 is kept high, and the crucible is not contaminated by non-contact melting.
Is located slightly above, the bottom of the base metal remains the solidified portion 16a.

Therefore, when the molten metal 16 is poured into the casting space 4 of the water-cooled copper mold 3 shown in FIG.
The induction heating coil 37 provided on the outer peripheral side of the water-cooled copper crucible 33 shown in (3) is lowered to melt the solidified portion 16 a at the bottom, and the molten metal 16 is discharged from the molten metal outlet 35 in the arrow direction.

Thus, according to this embodiment, the conventional T
It is possible to cast an engine connecting rod, which was difficult with arc skull melting centrifugal casting, which is a general casting method for i or Ti alloys, and it is possible to cast molten metal at a relatively low temperature into a ceramic or metal mold by the conventional casting method. Since it was forced to cast inside, defects such as temperature drop of molten metal, gas entrainment and defective bathing occurred, resulting in a low yield rate, and casting with a weight exceeding the melting capacity. Since it was difficult to manufacture, as a result, the product cost increased and the predetermined performance and the product price became unbalanced, which hindered the spread of Ti and Ti alloy engine connecting rods. According to the present invention, the conventional problems are solved, and the gas contained in the molten metal is floated by using a water-cooled copper mold having a heating ability for the molten metal. Since it is designed to cast a molten metal that has a sufficient temperature for cooling, defects such as gas entrapment and defective melt flow are rarely generated. Since no shrinkage cavities occur in the mold, and because the water-cooled copper mold can be used repeatedly, it is possible to reduce the cost. Therefore, the engine connecting rod of Ti or Ti alloy can be priced appropriately. It became possible to manufacture other castings.

[0033]

Since the casting manufacturing method and manufacturing apparatus according to the present invention have the above-mentioned structure, the molten metal is not contaminated, the influence of gas entrainment during casting is eliminated, and the solidification shrinkage of the central portion is achieved. The effect of the above can be made small, and a remarkable effect that a casting having excellent internal quality can be produced is brought about.

[Brief description of drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an embodiment of a casting manufacturing apparatus according to the present invention.

2 is a horizontal cross-sectional explanatory view of the water-cooled copper mold taken along the line AA ′ in FIG.

FIG. 3 is an external view of a tiltable water-cooled copper melting furnace used for pouring molten metal into the casting manufacturing apparatus shown in FIG.

FIG. 4 is a vertical cross-sectional view of a furnace bottom tapping type water-cooled copper melting furnace used for pouring molten metal into the casting manufacturing apparatus shown in FIG.

[Explanation of symbols]

1 Casting manufacturing equipment 3 Water-cooled copper mold 4 casting space 11 Induction heating coil (induction heating means) 16 Molten metal 21, 31 Water-cooled copper melting furnace (molten metal container)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B22D 27/04 A 7011-4E H05B 6/24 8915-3K 6/40 8915-3K

Claims (10)

[Claims] 1. Induction heating is performed by heating the molten metal poured from a molten metal container into a water-cooled copper mold by induction heating, partially delaying the solidification of the molten metal by the induction heating to eliminate gas bubbles and the like. And then solidifying in the water-cooled copper mold. 2. The method for producing a casting according to claim 1, wherein the melting atmosphere and the casting atmosphere are controlled atmospheres such as inert gas and vacuum. 3. A molten metal poured from a molten metal container into a water-cooled copper mold is heated by induction heating, the induction heating delays the solidification of the molten metal on the upper side, and bubbles of gas etc. are levitated. The method for producing a casting according to claim 1, wherein heating is stopped. 4. The directional solidification of the molten metal poured into the water-cooled copper mold by sequentially stopping the induction heating from the lower side toward the upper side and sequentially shifting the solidification site upward. The method for manufacturing a casting according to any one of 3 above. 5. A water-cooled copper mold in which the molten metal is poured from a molten metal container, and the molten metal in the water-cooled copper mold is heated by induction heating to partially delay the solidification of the molten metal to prevent gas and the like. An apparatus for producing a casting, comprising induction heating means for eliminating bubbles. 6. The apparatus for producing a casting according to claim 5, wherein the induction heating means is composed of a single induction heating coil and is movable in the upper direction so that the solidification of the molten metal is delayed on the upper side. . 7. The solidification of molten metal, wherein the induction heating means is composed of a plurality of induction heating coils arranged in a vertical direction, and the power can be cut off sequentially from the lower induction heating coil to the upper induction heating coil. The casting manufacturing apparatus according to claim 5, wherein the casting is delayed on the upper side. 8. The casting manufacturing apparatus according to claim 5, wherein the water-cooled copper mold is composed of divided segments which allow the casting to be taken out easily. 9. The casting manufacturing apparatus according to claim 5, wherein the water-cooled copper mold has a ceramic sprayed film for electrical insulation on the split surfaces of the split segments. 10. The molten metal container comprises a water-cooled copper melting furnace capable of tilting, a water-cooled copper melting furnace capable of tapping the bottom, a plasma heat source cold hearth, an arc heat source cold hearth,
The casting manufacturing apparatus according to any one of claims 5 to 9, which is selected from an electron beam heat source cold hearth.