JP2849536B2 - Mold sealing method enabling high differential pressure close casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold sealing method which enables high differential pressure close casting.

[0002]

2. Description of the Related Art Titanium / titanium alloy, which is a light specific gravity metal, for example, has high heat resistance and excellent toughness, abrasion resistance and mechanical properties, and is therefore used as a dental / orthopedic material. Conventionally, when titanium is melted and cast into a mold, pressure casting from above the mold is adopted.However, airtightness between the melting chamber and the casting chamber can be secured, Fine pressure casting is difficult because a differential pressure cannot be formed.

The applicant of the present invention has previously set the melting chamber volume V ₁ and the casting chamber volume V ₂ to V ₁ <V _{2 according} to the specification of Japanese Patent Application No. 4-214285 (JP-A-6-63721). The molten casting material is melted with a melting plate under an inert gas atmosphere, and the molten metal is injected into the casting chamber mold and simultaneously with the inert gas being injected into the melting chamber, forming a high pressure difference between the melting chamber and the casting chamber. Then, a high differential pressure ultra-fine casting method that maintains the high pressure difference until the casting solidifies was proposed.

[0004]

A high differential pressure must be created between the melting chamber and the casting chamber to maximize the differential pressure effect when the molten metal is pressed into the mold. The present invention provides a mold sealing method for high differential pressure close casting of a large casting by selecting a sealing position of a mold in a casting chamber.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when a differential pressure is formed between a melting chamber and a casting chamber to perform casting, a circle in which an inner periphery of a conical mold receiving stand provided in the casting chamber is filled with an airtight material is provided. Circumferential groove
Provided, mold runner and cavity molding using porous mold material
The body is provided, the boundary zone of the mold runner and cavity shaped bodies allowed position in the circumferential groove of the mold pedestal, enables high differential圧細dense casting and forming a high differential pressure in the melting chamber and the casting chamber Mold sealing method.

[0006]

According to the present invention, a mold receiving stand for setting a mold is formed in a conical shape, an edge piece is attached to the upper surface of the receiving stand of the mold receiving body, and a groove is engraved in the attached edge piece in a ring shape to fill the airtight material. . Further, a circular groove is formed in a plurality of stages by selecting a position on the inner peripheral portion of the mold receiving body, and a circular airtight material is filled in the circular groove to form a circular airtight level. On the other hand, when the molten metal is pressed into the mold, the boundary area between the hollow molded body of the casting and the runner is positioned at an annular hermetic level, so that the differential pressure effect is maximized and the molten metal is filled up to the dense part of the large casting. be able to.

FIG. 1 is an overall view of the present invention. In the figure, 7: porous mold, 10: melting chamber, 11: casting chamber, 1
2: purge injection hole, 13: suction hole, 17: solenoid switching valve. After replacing the atmosphere in the melting chamber 10 and the casting chamber 11 with the inert gas, a high pressure difference is formed in the melting chamber and the casting chamber prior to the injection of the molten metal. → Connection port 1 from casting room 11
The exhaust gas is discharged out of the system by the electromagnetic switching valve 17 through 6. That is, a low and high pressure inert gas whose pressure is set from a cylinder is injected into the melting chamber 10 to make the melting chamber 10 a high gas pressure, and a high gas pressure acts on the upper part of the mold. Casting room 1 before pouring
1 is set to a low pressure, and a high differential pressure is obtained by the relative to the above-mentioned high gas pressure, so that ultra-fine casting is possible.

As shown in FIGS. 2 and 3, a mold receiving table 1 on which a mold is set is formed in a conical shape and has a circumferential groove 3-1.
3-2 is engraved. A plurality of circumferential grooves 3 are provided in the longitudinal direction of the mold receiving table 1. An edge piece 4 is attached to the upper surface of the mold receiving base 1, an annular groove 5 is formed in the edge piece 4, and an airtight material 6 is provided in the annular groove 5.
Fill. The material of the airtight material 6 is not particularly limited as long as it is a material such as a heat-resistant rubber / resin or a metal ring which secures sealing properties. On the other hand, the casting mold is made of a porous investment material, but is formed of a gate A, a runner B and a hollow molded body C as shown in FIG.

According to the present invention, the inner shape of the mold receiver 1 is formed in a conical shape, so that the fitting between the mold receiver 1 and the mold 7 is stabilized, and a plurality of circumferential grooves are provided on the inner surface. Since the boundary area 20 between the hollow molded body and the runner is positioned at the airtight level where the airtight material is set, the airtight material 6 and the mold are pressed against each other when pressure is applied to the upper surface of the mold, and the high sealing property is improved. . That is, since the airtight level boundary region 20 is located at the upper edge of the hollow molded body, the pressure in the melting chamber is directly introduced into the casting chamber via the hollow molded body, and when the molten metal is poured using this pressure difference, fine casting can be performed. I do.

Although the mold receiving table 1 is detachable from the casting chamber through a partition wall 8, an annular groove is provided on the upper surface of the edge piece 4 and the airtight material 6 is filled, so that the molding chamber and the mold receiving table can be connected to each other. The airtightness is improved. That is, in the present invention, the boundary area between the hollow molded body C of the mold and the runner B is made to coincide with the sealing position of the airtight material 6 in the inner circumferential groove. By forming a high differential pressure between the melting chamber and the casting chamber (decompression chamber), a good and defect-free cast body for large products can be obtained.

FIG. 7 is an overall view of an apparatus to which the method of the present invention is applied. That is, the resin tube hose 23 is connected to the pressure reducing valve 22 connected to the gas cylinder (original pressure) 21, and the pressure is connected to the pressure accumulating tank 24. Further, it is connected to the melting chamber 10 via a high-pressure system and a low-pressure system connected to the pressure accumulation tank outlet side.
Reference numeral 25 denotes an evacuation vacuum pump. FIG. 8 is an example of the pressure-time of the operation of the present invention.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An application example of the present invention using the apparatus shown in FIG. 7 will be described.
As shown in FIG. 5, when a hollow molded body (hereinafter referred to as a cast body cavity) is formed above the hermetic material 6 filled in the annular circumferential groove of FIG. 2, the same gas pressure as that of the melting chamber 10 of FIG. 4 ~
7 kg / cm ² abs) is formed in the casting cavity, which impedes the inflow of titanium into the casting cavity, resulting in a casting with chipping.

As shown in FIG. 6, the boundary between the casting cavity and the runner is shown.
When the boundary area is formed in conformity with the annular circumferential grooves 3-1 and 3-2 in FIG. 2, the gas pressure in the melting chamber 10 and the gas pressure in the casting chamber 11 (0.5 kg / cm ^2). abs) to form a differential pressure. In addition, due to the ventilation characteristics (porous property) of the mold material, a gas body flows out of the casting cavity into the casting chamber, and the gas pressure in the melting chamber (4 to 7 kg /
cm ² abs). Here, JIS class 2 height 12mm,
Molten titanium (1700) having a cross-sectional diameter of 30 mm and a weight of 50 g
C.), a high-speed flow of titanium is generated due to the pressure difference between the melting chamber 10 and the casting chamber 11 to enable complete formation up to the fine tip.

[0014]

According to the present invention, high airtightness in the melting chamber and the casting chamber can be obtained. In casting, the gas press-fitted into the melting chamber is uniformly loaded on the hollow molded body and exhausted into the casting chamber. It is possible to cast an excellent ultra-fine casting of the product.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is a partial perspective view of the present invention.

FIG. 3 is an explanatory diagram of a main part of the present invention.

FIG. 4 is a schematic view of a mold of the present invention.

FIG. 5 is an explanatory diagram of an operation of a comparative example of the present invention.

FIG. 6 is a diagram illustrating the operation of the present invention.

FIG. 7 is an explanatory diagram of an apparatus to which the present invention is applied.

8 (a), (b) and (c) are pressure-time charts of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold receiving stand 3 Circumferential groove 6 Airtight material 10 Melting room 11 Casting room

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // A61C13 / 20 A61C13 / 20 D (56) References JP-A-55-70465 (JP, A) JP-A-55- 165266 (JP, A) JP-A-49-123431 (JP, A) JP-A-6-292962 (JP, A) JP-A-56-37673 (JP, A) Japanese Utility Model Laid-Open No. 55-98467 (JP, U) 57-92461 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B22D 18/06

Claims (1)

(57) [Claims] 1. An inner periphery of a conical mold receiving stand provided in a casting chamber when casting by forming a differential pressure between a melting chamber and a casting chamber.
A circumferential groove filled with airtight material is provided on the
The mold runner and cavity molding are provided by using, and the boundary area between the mold runner and the cavity formation is located in the circumferential groove of the mold receiving stand, and a high differential pressure is formed between the melting chamber and the casting chamber. Mold sealing method that enables dense casting with high differential pressure.