JPH0871733A - Sand mold casting device - Google Patents

Abstract

PURPOSE: To prevent the development of misrun and chilled crack in the thin part of a casting by executing electromagnetic induction heating to molten metal filled up in a cavity in a sand mold and a casting in the sand mold. CONSTITUTION: The electromagnetic induction heating part 3 is arranged between a molten metal pouring part 1 and a casting taking-out part 4. The electromagnetic induction heating part 3 is provided with a first heating coil 31 and a second heating coil 32, and a first electric power control part 33 and a second electric power control part 34 are connected to the first and the second heating coils 31, 32, respectively. Further, a heating control part 35 is connected to the first and the second electric power control parts 33, 34. The electromagnetic induction heating is executed to the molten metal filled up into the cavity 24 in the vertical type flaskless sand mold 22 with the first heating coil 31 and successively, to the casting 41 in the vertical type flaskless sand mold 22 with the second heating coil 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a sand casting machine, and more particularly to a sand casting machine for casting thin castings.

[0002]

2. Description of the Related Art As a conventional casting apparatus, a pouring section for pouring molten metal into a cavity of a sand mold, a casting take-out section for taking out a casting cast with the molten metal from a sand mold, a pouring section and a casting take-out section. There is a sand mold casting device which is provided between the sand mold and the sand mold and which conveys the sand mold in which the molten metal is poured to the casting take-out part (for example, Japanese Patent Laid-Open No. 1-215456).
Issue).

[0003]

When casting a casting using a conventional sand casting apparatus, it is possible to cast a good casting without casting defects when casting a casting without a thin portion. When casting a casting having a thin portion, there is a problem that the cavity portion forming the thin portion is not sufficiently filled with molten metal and defective casting tends to occur in the casting.

On the other hand, even if the molten metal in the thin-walled portion is sufficiently filled with the molten metal, if the molten metal in the thin-walled portion is rapidly cooled, the rapidly cooled portion is chilled and chill cracks are likely to occur. There is.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a sand casting apparatus in which a molten metal defect and a chill crack are less likely to occur in a thin portion of a casting.

[0006]

A sand mold casting apparatus of the present invention comprises a pouring part for pouring molten metal into a cavity of a sand mold, and a casting take-out part for taking out a casting cast with the molten metal from the sand mold. A sand mold transporting unit that is provided between the pouring unit and the casting unloading unit and that transports the sand mold in which the molten metal has been poured to the casting unloading unit. An electromagnetic induction heating section having at least two heating coils is provided in the middle of the carrying step of
Electromagnetic induction heating of molten metal or semi-molten metal in the sand mold with a first heating coil provided on the pouring part side, and heating after a second heating coil provided on the casting extraction part side with respect to the first heating coil. A coil is used for electromagnetic induction heating of a casting that is cooled and solidified in the sand mold.

The position at which the electromagnetic induction heating section is provided is not particularly fixed, and it may be provided adjacent to the pouring section or separately from the pouring section. The electromagnetic induction heating may be performed immediately after pouring the molten metal or after a predetermined time has elapsed, but the first heating coil and the second heating coil are arranged at a predetermined distance.

The type of the heating coil is not particularly limited, and various winding shapes such as a solenoid shape and an elliptical shape are allowed, and various sectional shapes such as a circular shape, a square shape, and a rectangular shape are allowed.

[0009]

[Function] After pouring molten metal into the sand mold cavity,
The sand mold is conveyed toward the casting take-out portion via the sand mold conveying section. At that time, the molten metal poured into the cavity or the semi-molten metal in which a part of the molten metal is solidified in the cavity is electromagnetically induction-heated by the first heating coil of the electromagnetic induction heating unit and melted at a high temperature. The molten metal having good property flows into and is filled into every corner of the cavity.

Then, the molten metal filled in the cavity is solidified to form a casting, and the casting is electromagnetically heated by each heating coil after the second heating coil of the electromagnetic induction heating unit, and the sand mold The casting annealed therein is conveyed to the casting take-out section. At this time, since the sand mold is not heated in the electromagnetic induction heating section, cooling is performed in the same manner as in the case where the electromagnetic induction heating of the molten metal or the casting is not performed.

[0011]

EXAMPLES Examples of the present invention will be described below with respect to a frameless sand casting apparatus. FIG. 1 shows a frameless sand casting apparatus, which is composed of a pouring section 1, a sand carrier section 2, an electromagnetic induction heating section 3 and a casting removal section 4.

The pouring part 1 is a ladle 12 and a ladle 12 for pouring the molten metal 11 into the cavity 24 of the vertical frameless sand mold 22.
And a ladle tilting device (not shown) for tilting the ladle at any angle.

The sand mold conveying section 2 is formed of a long slide plate 21 extending horizontally from the pouring section 1 side toward the casting unloading section 4 side and an extrusion cylinder of a molding machine (not shown). The front end of 21 is bent obliquely downward, and a vertical vertical frameless sand mold 22 formed on the slide plate 21 is placed so as to be able to move forward from the pouring part 1 side toward the casting unloading part 4 side. . A cavity 23 is divided into halves on the front surface and the rear surface of each vertical frameless sand mold 22, and a cavity 24 is formed when the vertical frameless sand mold 22 is matched.

The electromagnetic induction heating section 3 includes a first heating coil 31 provided near the ladle 12, a second heating coil 32 provided at a predetermined distance (δ) from the first heating coil 31, and It is formed of first and second power control units 33 and 34 respectively connected to both heating coils 31 and 32, and a heating control unit 35, and both power control units 33 and 34 are connected to the heating control unit 35 and an external power supply 36. The first and second heating coils 31, 32
The electric power controlled by the first and second electric power control units 33 and 34 is supplied from the external power source 36 according to the instruction of the heating control unit 35.

The heating coils 31 and 32 are formed of solenoid coils, and the slide plate 21 is inserted through the internal space of the heating coils 31 and 32, and the vertical frameless sand mold 22 is formed so as to pass therethrough. , The heating coils 31, 3
A heating coil support member 37 that forms a magnetic circuit when energized is fitted around the outer periphery of 2.

The casting take-out section 4 is a casting take-out tool (not shown) for taking out the cast 41 from the collapsed vertical frameless sand mold 22.
And a conveyor 42 for discharging foundry sand.

Next, the operation will be described. The vertical vertical frameless sand molds 22 that have been molded are sequentially sent out from the frameless molding machine (not shown) onto the slide plate 21, and when the vertical vertical frameless sand molds 22 are matched on the slide plate 21, they are adjacent to each other. A cavity 24 is formed between each vertical frameless sand mold 22.

When the vertical frameless sand mold 22 moves forward to the ladle 12, the molten metal 11 at 1400 ° C. is poured from the ladle 12 into the cavity 24 of the vertical frameless sand mold 22 (see FIG. Point A in 2.) Then, when the vertical frameless sand mold 22 passes through the inside of the first heating coil 31 to which the predetermined power is supplied,
The molten metal 11 cooling in the cavity 24 is the first
The molten metal 11 heated by electromagnetic heating (between points B and C in FIG. 2) by the heating coil 31 and held at about 1400 ° C. flows into and fills every corner of the cavity 24.

After that, the vertical frameless sand mold 22 is attached to the slide plate 2.
While advancing over 1, the molten metal 11 in the cavity 24 is solidified to form a casting 41. When the casting 41 cools to about 900 ° C. (point D in FIG. 2) and the vertical frameless sand mold 22 passes through the inside of the second heating coil 32 to which a predetermined power is supplied,
The casting 22 is subjected to electromagnetic induction heating by the heating coil 32 and is maintained at about 900 ° C. While the vertical frameless sand mold 22 passes through the second heating coil 32 (point E in FIG. 2) and moves forward on the slide plate 21, the casting 41 is cooled in the vertical frameless sand mold 22 and baked. Be fooled.

The vertical frameless sand mold 22 is not subjected to electromagnetic induction heating by the first and second heating coils 31 and 32, so that the casting 4
After 1 passes through the second heating coil 32, it is cooled in substantially the same manner as the casting in the vertical frameless sand mold 22 that is not subjected to electromagnetic induction heating.

After that, the vertical frameless sand mold 22 is attached to the slide plate 2.
1, the vertical frameless sand mold 22 collapses due to its own weight at the tip inclined portion of the slide plate 21, and the casting 41 and the casting sand fall on the conveyor 42. Then, casting 41
Is taken out of the conveyor 42 by a casting take-out tool (not shown), and the foundry sand is discharged by the conveyor 42.

The casting apparatus of the present invention can be applied not only to the frameless sand type casting apparatus but also to the framed sand type casting apparatus. As the sand mold, not only the vertical unframed sand mold, but also the horizontal unframed sand mold, the framed sand mold, the mold for vanishing model casting filled with dry sand, and the like can be used. When the framed sand mold is used, it is desirable that the flask be made of a non-conductive and non-magnetic material.

[0023]

According to the present invention, defective casting and the occurrence of chill cracks are prevented, and good castings free from casting defects can be cast with high yield.

[Brief description of drawings]

FIG. 1 is a front sectional view of a sand casting apparatus according to the present invention.

FIG. 2 is a graph showing temperature changes of the molten metal and the casting in the sand mold.

[Explanation of symbols]

 2 sand mold conveying part 3 electromagnetic induction heating part 4 casting removal part 22 sand mold 31 first heating coil 32 second heating coil 41 casting

Claims (1)

[Claims] 1. A pouring part for pouring molten metal into a cavity of a sand mold, a casting take-out part for taking out a casting cast with the molten metal from the sand mold, the pouring part and the casting take-out part. A sand mold casting apparatus having a sand mold transporting unit for transporting the sand mold in which the molten metal is poured to the casting removal unit, wherein at least two heating operations are performed during the transporting process of the sand mold transporting unit. An electromagnetic induction heating unit having a coil is provided, and the molten metal or semi-molten metal in the sand mold is electromagnetically induction heated by the first heating coil provided on the pouring unit side, and the casting extraction unit side from the first heating coil. A sand mold casting apparatus, wherein a casting coil cooled and solidified in the sand mold is subjected to electromagnetic induction heating by a heating coil subsequent to the second heating coil provided in.