JPH06234063A - Method for removing molding sand - Google Patents

Abstract

PURPOSE:To provide the method for removing molding sand capable of removing the molding sand in a short time. CONSTITUTION:A casting 2 which is an object to be treated is installed in liquid and high-pressure liquid is in-liquid injected through a nozzle 1 for jet injection which consists of an orifice part for increasing the flow velocity of the supplied liquid and an injection route which is arranged downstream of the orifice part and has the sectional area expanded than the orifice part and the cavitation jet blow is made to generals. The molding sand 3 sticking to the casting 3 is removed by the cavitation jet flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing foundry sand.

[0002]

2. Description of the Related Art For the production of various castings such as cast iron castings, steel castings, alloy castings, the ease of making molds and the low price,
BACKGROUND ART So-called sand mold casting, in which a mold is made of sand and each metal is poured into the sand mold to produce a casting, is most widely used today because of the fact that the mold material can be used repeatedly.

This sand mold casting is a molding in which a mold is made of various types of molding sand, a molten metal, that is, a molten metal of high temperature is poured into the manufactured mold, a casting is taken out of the mold, and the molding sand is attached to the casting. It is carried out through steps such as cleaning and removing the core.

In such a sand mold casting, a conventional method of removing the foundry sand (core) from the foundry product removed from the mold by unmolding is, for example, by infiltrating the foundry sand adhering to the foundry product with a caustic soda solution. There are a caustic soda treatment method of removing the sand and a high-pressure water jet method of spraying high-pressure water jetted from a nozzle onto the foundry sand to remove the foundry sand by its energy.

[0005]

However, the conventional method for removing foundry sand has the following problems.
That is, in the caustic soda treatment method, it takes a long time (the permeation rate is about 20 mm / day, depending on the type of the foundry sand) until the caustic soda solution permeates into the core, and therefore the work efficiency is high. Is a problem with.

Further, in the high-pressure water injection method, it is possible to make holes (removal of sand) with a diameter that is 2 to 3 times the diameter of the nozzle, and depending on the object to be treated, a shorter treatment time than the caustic soda treatment method is possible. However, the processing (removal) speed is still unsatisfactory, and especially when removing the foundry sand (core) surrounded by the casting, the casting has a bent portion and the core ( (Casting sand) is not in a straight line with respect to the jet water flow, there is a problem that high pressure water hits the bent portion and the energy of the high pressure water is lost, and it takes a long time to remove the casting sand. .

The present invention solves the problems of the conventional method for removing foundry sand, and an object of the present invention is to provide a method for removing foundry sand that can remove foundry sand in a short time. is there.

[0008]

[Means for Solving the Problems] To achieve the above object,
In the present invention, a casting to be treated is placed in a liquid, and an orifice portion that increases the flow velocity of the supplied liquid with respect to the casting and is disposed downstream of the orifice portion and is enlarged than the orifice portion. A casting characterized in that a high-pressure liquid is jetted into a liquid through a jet jet nozzle having a jet path having a cross-sectional area to generate a cavitation jet, and the casting sand adhering to the casting is removed by the cavitation jet. It relates to a sand removal method.

[0009]

In the present invention, a casting to be treated is placed in a liquid, and a high-pressure liquid flow is jetted into the casting sand adhering to the casting through the jet jet nozzle.

Here, as described above, the jet injection nozzle has an orifice portion for increasing the flow velocity of the supplied liquid and an injection portion which is arranged downstream of the orifice portion and has an enlarged cross-sectional area than the orifice portion. By providing a high-pressure liquid to such a nozzle, a cavitation jet flow is formed, and the casting sand removes the foundry sand.

Here, the cavitation jet flow means a high-speed jet flow jetted from a nozzle, countless depressurized bubbles generated by unstable collision and agitation of surrounding liquid, and small strong vortices surrounding the bubbles. A high-speed liquid flow including
It significantly increases the energy compared to a simple high velocity liquid flow without bubbles.

In the vicinity of the surface of the object to be ejected, high-pressure water is generated due to the damming of the high-speed liquid flow, the bubbles are crushed and a shock wave is emitted, and the liquid accelerated by the shock wave is the object to be ejected. Since it gives a strong impact to the surface, it is faster and faster than the conventional case where a high-pressure liquid is sprayed in the air to remove the foundry sand, or the case where a conventional submerged jet flow that does not use cavitation is used. The effective removal can be performed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the casting sand removal method of the embodiment, the casting that is the object to be treated is installed in a liquid, and the casting sand adhered to the casting by injecting a high-pressure liquid into the liquid through a jet injection nozzle. Remove.

Here, as the jet injection nozzle, a horn-type submerged jet injection nozzle previously proposed by the applicant of the present invention for producing the cavitation injection flow (Japanese Patent Application No. 59-25681 (Japanese Patent Publication No. -43712
No.)) is used.

That is, as shown in FIG. 3, this horn type submerged jet nozzle is connected to a high-pressure liquid supply source 7 to increase the flow velocity of the liquid flow from the supply source 7 to form a high-speed jet flow. With an orifice portion 31a formed of a tubular passage having a constant cross-sectional area, and extending from the outlet of the orifice portion 31a in the axial direction and having a length L that is 4 to 20 times the diameter of the orifice portion 31a, The orifice portion 31a is provided with an ejection hole 31b having a cross-sectional shape in which the diameter gradually increases from the inlet portion having the same diameter as the orifice portion 31a in the axial direction at an angle of 20 ° to 60 ° with the axial center C. Is.

Preferably, the angle θ _W is 20 °.
Use a thing of -40 degrees. The angle θ _W is effective in the range of 20 ° to 60 ° as described above in order for the jetted liquid to generate a cavitation phenomenon between itself and the surrounding liquid, and is particularly remarkable in the range of 20 ° to 40 °. It is possible to obtain various cavitations, reduce the energy attenuation of the spray liquid, and effectively apply the spray energy to the molding sand that is the spray object.

The length L of the ejection hole 31b is effectively 4 to 20 times the diameter L of the orifice portion 31a as described above, but the orifice portion 31a is effective.
It is preferable to use one having a diameter of 5 to 12 times, because the remarkable effect can be exhibited.

Further, the outlet opening of the orifice portion 31a may have a circular cross section, an elliptical cross section or a rectangular cross section.

When the horn type nozzle 31 is submerged in the liquid and a high-pressure liquid is supplied, the high-speed jet flow flowing out from the orifice portion 31a to the jet passage 31b is limitedly protected by the jet passage 31b and has a limited volume. A turbulent high-speed liquid flow centered on the jet flow is formed by entraining the surrounding liquid in the inside of the chamber, and the action of strong Reynolds stress τ generated in this high-speed liquid flow forms depressurized bubbles and small vortices. It

The depressurized bubbles and the small vortices store a part of the energy of the original jet flow, are dispersed in the high-speed liquid and are made to flow, and collide with the foundry sand adhering to the foundry to generate a high-vibration shock wave. By this, the foundry sand adhering to the foundry is removed.

As the nozzle, a submerged jet jet nozzle 41 shown in FIG.
(Japanese Patent Application No. 4-47709) can also be used. As shown in FIG. 4, the nozzle 41 includes an orifice portion 41a having an inner diameter d _{0 and} an injection path 41b following the orifice portion 41a,
The injection path 41b has a flat surface 411b at the inlet and an inner diameter D.
And a cylindrical surface 411c having a length L. The entire nozzle 41 is machined in one piece from a super-hard material and has a rotationally symmetrical shape about the central axis C.

In order to confirm the effect of the foundry sand removal method of the present invention, the present inventor conducted the following experiment.

That is, as shown in FIG. 2, the object to be treated consists of an inner tube 2a and an outer tube 2b.
The casting 2 in which the space between a and 2b is partitioned by a plurality of partition walls 2c is used, and the inner pipe 2a, the outer pipe 2b, and the partition wall 2c are used.
The hard lost wax core (cast sand) remaining in the area surrounded by is removed. In addition, in the figure, the thickness of the tube wall and the partition wall is omitted. The casting has an outer diameter of about 360 mm and a height of 250 mm, and one side of the upper surface of the portion surrounded by the inner pipe, the outer pipe and the partition wall is about 30 mm.

Such a casting 2 was placed in water, and as shown in FIG. 1, high pressure water was jetted to the core 3 by the horn type submerged jet jet nozzle 1 shown in FIG.
The distance from the tip of the nozzle to the upper surface of the casting 2 (core 3) was 100 times or less the nozzle diameter, and the pressure of water supplied to the nozzle 1 was 700 kgf / cm ² . Also, FIG.
Then, the outer peripheral portion of the casting 2 shown in FIG. 2 is partially enlarged.

As a result of comparison with the case of injecting in the air with the same pressure and the same amount of water using the conventional nozzle having the same diameter, the time until the penetration of the core 3 is removed is about 1 of the air injection. / 3 to 1/5, and the removal volume is 5 to 5 of the air injection.
It turned out to be 10 times. As described above, according to the method for removing foundry sand of the present embodiment, it is possible to remove foundry sand in a significantly shorter time than the conventional method for removing foundry sand.

Further, according to the present method, the effect of removing the foundry sand can be improved with a smaller injection flow rate and lower water pressure, as compared with the conventional air injection method.
It is possible to save energy, and since this method uses in-liquid injection, it is not necessary to take measures against mist during the removal work.

It is also possible to mix a heating agent for dissolving the hardened molding sand into the high-pressure water supplied to the nozzle or to heat the same.

Further, it goes without saying that not only the core can be removed, but also the molding sand adhering to the outer surface of the casting can be removed.

[0029]

As described above, according to the present invention,
As compared with the conventional method for removing foundry sand, the foundry sand can be removed in a significantly shorter time, and the work efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an experiment conducted to confirm the effect of the present invention.

FIG. 2 is a perspective view showing a casting used in the experiment.

FIG. 3 is a vertical cross-sectional view showing the configuration of a liquid jet injection nozzle used in a method for removing foundry sand according to an embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing the configuration of another liquid jet jet nozzle that can be used in the method for removing foundry sand according to the present invention.

[Explanation of reference numerals] 1,31,41 Nozzles for jetting in liquid 2 Casting 3 Casting sand (core)

Claims (1)

[Claims] 1. A casting, which is an object to be treated, is placed in a liquid, and an orifice portion that increases the flow rate of the supplied liquid with respect to the casting and is disposed downstream of the orifice portion and is enlarged than the orifice portion. Characterized in that a high-pressure liquid is jetted into the liquid through a jet jet nozzle having a jet path having a different cross-sectional area to generate a cavitation jet flow, and the cavitation jet flow removes casting sand adhering to the casting. Foundry sand removal method.