JPS6334789Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mold for forming metal accessories, crafts, dentures, industrial accessories, etc.

Pressure pouring and vacuum suction differential pressure casting are excellent precision casting methods for casting fine items such as jewelry, but in this case, the mold must be securely fixed to the molten metal inlet. . On the other hand, since a sprue communicating with the runner is formed on the top surface of the mold, the contact area of the top surface of the mold with the spout becomes small, and when pressure is applied to securely fix the mold to the spout, the top surface of the mold was sometimes damaged.

For this reason, conventionally, a ring frame used during mold forming is used so that the tightening force of the mold is received by the ring frame. However, since the outer peripheral surface of the mold is covered with a ring frame,
A disadvantage is that the air present in the mold cavity during casting is difficult to escape through the mold material.

In view of this, the present invention provides a mold that can be securely fixed to the molten metal inlet without using a ring frame, and for this purpose, a ceramic sprue frame is provided on the upper surface of the mold body. As a result, the upper end of the mold is reinforced with a ceramic sprue frame, and air can escape from the outer circumferential surface of the mold.Furthermore, the upper surface of the mold body is recessed into a tapered and sloping shape to improve this slope. In addition to being formed into a step-like shape, the lower surface of the peripheral wall of the sprue frame projects in a tapered and sloping shape, and this slope is formed into a step-like shape, so that the lower surface of the sprue frame is in contact with the upper surface of the mold body. This increases the contact area between the mold body and the sprue frame to improve adhesion and eliminate mold deformation when pressurized.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a longitudinal sectional view of the main parts of an argon arc melting precision casting apparatus. The casting apparatus C has a mold body 1 made of aluminum alloy as its basic structure, inside which a melting chamber 2 and a casting chamber 3 are divided into upper and lower sections by partition walls 4. A copper pedestal 5 is fixed to the center of the partition wall 4 in a penetrating manner, and a passage hole 6 is bored in the center of the pedestal 5. A copper crucible 7 is placed in the melting chamber 2 and a mold 8 is placed in the casting chamber 3 with the passage hole 6 in between, and these are placed in contact with the upper and lower surfaces of the pedestal 5. An arc discharge electrode 9 is located in the center of the upper space of the melting chamber 2, and a crucible 7
It is arranged to face the melting material 10 placed above from above. An outflow hole 11 is provided in the center of the crucible 7.

The mold 8 housed in the casting chamber 3 is placed on the receiving plate 12, and by tightening the handle 13, it is pushed up by the peripheral cam type jack 14 via the rod 15 and the receiving plate 12, and is sealed. Hold the pedestal 5 with the tool 16 in between.
is brought into airtight contact with the underside of the

This mold 8, as shown in FIGS. 2 and 3,
Cylindrical mold body 18 formed of breathable investment material 17
It is a ringless mold with an unglazed ceramic sprue frame 20 fixed to the upper end of the mold. The upper surface 29 of the mold body 18 is formed with a conical recess,
Furthermore, this conical inclined surface is formed in a step-like shape. Further, the upper surface 19 of the peripheral wall of the sprue frame 20 is formed into a flat surface, and the lower surface 30 is formed to protrude in a conical shape, and furthermore, this conical outer peripheral surface 22
is formed in a step-like shape, and a sprue 21 is recessed in the center of the sprue frame 20.

This sprue frame 20 serves as a pattern support during mold formation, and a sprue wire 24 with a wax pattern 23 attached to the sprue 21 of the sprue frame 20 in an inverted position
is fitted, and a synthetic resin ring frame 25 is fitted to the sprue frame 20 in a state surrounding the wax pattern 23 and sprue wire 24, and the ring frame 25 is filled with the breathable investment material 17 and solidified. Thereafter, the ring frame 25 is removed and a normal dewaxing process is performed to form a ringless mold body 18. Reference numeral 26 represents the sprue that is created after the sprue line 24 is removed, and 27 is the molding space that is created after the wax pattern 23 is removed.

Note that the sprue frame 20 may be placed and fixed on the upper end of the mold body 18 formed using a crucible former. Further, annular protrusions or annular grooves may be formed concentrically on the upper surface of the peripheral wall of the sprue frame 20, so that the upper surface of the peripheral wall of the sprue frame 20 has approximately the same height over the entire circumference. In this case, by using an O-ring as the sealing member 16 and having a structure in which the O-ring fits between the annular protrusions or into the annular groove, the upper surface 19 of the sprue frame 20 is airtightly attached to the lower surface of the pedestal 5. You can make them win. Similar to airtight contact by surface contact as in this embodiment, airtight contact by line contact using a plurality of O-rings is also an effective means.

Furthermore, the sprue frame 20 does not need to have a conical outer circumferential surface formed in a stepped shape, but may have a tapered outer circumferential surface such as a hemispherical shape formed in a stepped shape.

FIG. 4 shows a ringless mold 8 for casting a relatively large item, and a sprue frame 20 is fixed on the upper surface of a mold body 18 formed of investment material 17 with its sprue 21 aligned with the sprue 26. It has been done.

As mentioned above, in this invention, the mold used for precision casting is a ringless mold with a ceramic sprue frame fixed to the upper side of the mold body, so the contact force when setting the mold is reduced by the contact force of the sprue frame. The entire circumference of the upper surface prevents damage to the mold body.

Furthermore, the sprue formed in the ceramic sprue frame and the molten metal receiving surface can be pressurized with high precision to improve the surface accuracy and dimensional accuracy of the molten metal receiving surface, etc. The sprue frame can increase the heat resistance against high-temperature molten metal, so the heat resistance of the casting sand as a whole does not need to be increased so much, and the overall process can be carried out at low cost.

Moreover, the upper surface of the mold body is recessed in a tapered and sloping shape to form this sloping surface in a step-like shape, and the lower surface of the peripheral wall of the sprue frame is protruded in a tapered and sloping shape to form this sloping surface in a step-like shape. Since the lower surface of the sprue frame is brought into contact with the upper surface of the mold body, the contact area between the mold body and the sprue frame is increased, resulting in improved adhesion. Therefore, gas leakage from between the mold body and the sprue frame is sufficiently prevented, and a drop in internal pressure is prevented.

Furthermore, as mentioned above, the contact surface between the mold body and the sprue frame is formed in a stepped shape, so this flat surface absorbs the force applied to the top surface of the sprue frame and mold body when pressurized. This eliminates mold deformation.

Furthermore, since it is a ringless mold, the air in the molding cavity easily escapes from the mold body, allowing for good precision casting without causing casting defects.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of an argon arc melting precision casting machine, Figure 2 is an enlarged sectional view of the mold, Figure 3 is an exploded perspective view of the mold in the middle of molding, and Figure 4 is the second part of the large-diameter ringless mold. It is a figure equivalent figure. 17... Investment material, 18... Mold body, 19...
Top surface of 18, 20...Gate frame, 21...Gate, 2
3...Pattern, 24...Sprue line, 25...
Ring frame, 26... sprue, 27... pattern cavity.

Claims (1)

[Claims for Utility Model Registration] 1. The investment material 17 is filled in the ring frame 25 so as to surround the pattern 23 and the sprue wire 24, and the investment material 17 is solidified to form a mold body 18. Remove the ring frame 25, remove the pattern 23 and the sprue wire 24,
A sprue 26 and a pattern cavity 27 are formed in a ringless mold body 18, a ceramic sprue frame 20 is arranged on the upper surface 29 of the mold body 18, and the upper surface 29 of the mold body 18 is recessed in a tapered and inclined shape. The sloped surface of the lever is formed in the shape of a step, and the lower surface 30 of the peripheral wall of the sprue frame 20 is tapered and protrudes in a sloped shape to form this sloped surface in the shape of a step.
The lower surface 3 of the sprue frame 20 is attached to the upper surface 29 of the mold body 18.
0, and the bottom of the sprue 21 recessed in the center of the sprue frame 20 is connected to the sprue 26
A ringless mold for precision casting, characterized in that the upper surface 19 of the peripheral wall of the sprue frame 20 is formed at approximately the same height over its entire peripheral surface. 2. In the ringless mold for precision casting described in paragraph 1 of the claims for utility model registration, the sprue frame 20
is fixed so as to be integrated with the mold body 18. 3. In the ringless mold for precision casting described in claim 1 of the utility model registration claim, the sprue frame 20
is placed and fixed on the upper surface 29 of the mold body 18. 4. The ringless mold for precision casting described in claims 1, 2, or 3 of the utility model registration claim, in which the upper surface 19 of the sprue frame 20 is formed into a flat shape. 5. The ringless mold for precision casting described in paragraphs 1, 2, or 3 of claims for utility model registration, in which an annular protrusion is formed on the upper surface 19 of the sprue frame 20. 6. A ringless mold for precision casting as set forth in claims 1, 2, or 3 of the utility model registration claim, in which a plurality of annular grooves are carved on the upper surface 19 of the sprue frame 20.