JPS592575B2 - Freezing mold manufacturing method and its equipment - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a method for manufacturing a frozen mold and an apparatus therefor.

Recently, a method for making a frozen mold as shown in FIG. 1 has been developed.

That is, first, sand, water, bentonite, and drowning powder are kneaded and compacted to fill a mold (wooden mold, metal mold, resin mold, etc.), and after the mold is removed, a coolant such as liquid nitrogen is poured into the mold. The idea is to create a strong mold by spraying the surface and freezing the water contained within the mold.

However, in the above-mentioned process, the mold removal operation is based on green molding, so the molding sand in the mold lacks sufficient cohesive force, and therefore the mold easily collapses during the mold removal operation, requiring a skilled worker. shall be.

Also, the water in the mold is then frozen.
As mentioned above, if you just spray a coolant such as liquid nitrogen onto the surface of the M mold, the moisture near the surface of the mold will easily freeze, but the moisture inside the mold will not freeze. That was difficult.

In view of the drawbacks of the above-mentioned freezing mold manufacturing technology, the present invention
Before filling the mold with molding sand, the molding sand is cooled and moisture is supplied to the surface of the molding sand particles. This attempt was made to eliminate the above-mentioned drawbacks by freezing the water.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

In the figure, reference numeral 1 denotes a cooling pipe made of a cylindrical steel tube, and inside the cooling pipe 1, from the top to the bottom, there is a primary cooling chamber 2, a secondary cooling chamber, which will be described in detail below. A cooling chamber 3 and a moisture supply chamber 4 are respectively formed.

The upper end of the cooling pipe 1 is open, and the foundry sand S is replenished through the opening, and it also serves as a discharge port for the gasified coolant.

First, reference numeral 2 denotes a primary cooling chamber formed at the top of the cooling pipe 1, which is separated from a secondary cooling chamber 3 formed adjacently at the bottom by a partition wall 5 described below. ing.

That is, the partition wall 5 is formed into a conical shape so as to gradually move inward as it goes downward, and gas outlet ports 6 are provided at the middle and high positions of the partition wall 5 for the primary cooling chamber 2 and the secondary cooling chamber 2. The cooling chambers 3 are formed to communicate with each other, and a first valve hole 7 is formed in the center of the lower end of the partition wall 5 .

Incidentally, a fin 8 is formed in the gas outlet 6 to prevent casting sand S, which will be described later, from falling toward the secondary cooling chamber 3.

Reference numeral 9 denotes a first valve body, which is provided at the center of the lower part of the primary cooling chamber 2 so as to be movable up and down. do.

Next, reference numeral 3 denotes a secondary cooling chamber, which is separated from a moisture supply chamber 4 formed adjacently below by a constriction section 10 described below.

In other words, the area around one-third higher from the lower end of the cooling pipe 1 is narrowed inward to have a V-shaped cross section, so that the narrowed portion 1
0 is formed, and a second
A valve hole 11 is formed.

Further, a second valve body 12 is provided at the center of the lower part of the secondary cooling chamber 3 so as to be movable up and down, and the second valve hole 11 is opened and closed by the up and down movement of the valve body 12.

Therefore, immediately below the first valve hole 7 in the secondary cooling chamber 3, a right conical umbrella-shaped guide cone 13 is provided to drop the foundry sand S in the form of a cylindrical thin-walled curtain, as will be described later. is,
Directly below the guide cone 13 is a cooling nozzle 14 that sprays a coolant R such as liquid nitrogen or liquid carbon dioxide horizontally and radially.

Note that 15 is a coolant supply pipe for supplying coolant.

Next, 4 is a moisture supply chamber, the lower end of which is squeezed inward to form a constricted part 16, and the center of the lower end of the constricted part 16 supplies molding sand S into the wooden mold. A sand discharge port 17 is provided.

Therefore, immediately below the second valve hole 11 in the moisture supply chamber 4, as will be described later, the foundry sand S cooled in the secondary cooling chamber 3 is dropped in the form of a cylindrical thin curtain. An umbrella-shaped guide cone 18 is provided, and a water supply nozzle 19 for spouting water W horizontally and radially is provided directly below the guide cone 18.

Note that 20 is a water supply pipe for supplying water.

Further, the outer periphery of the cooling pipe 1 corresponding to the secondary cooling chamber 2 and the secondary cooling chamber 3 is covered with a heat insulating material 21.

Continuing, the operation of the above embodiment will be specifically explained step by step.

■ First (see Figure 2), insert the first valve hole 7 into the first valve body 9.
The molding sand S is put into the primary cooling chamber 2 in a closed state.

Note that it is preferable that this feeding needle feeds at least twice as much molding sand S as the amount to be treated at one time.

This is because the cooling effect in the step ① below can also be used for the foundry sand S to be processed next time.

Thereafter, with the second valve hole 11 closed by the second valve body 12, the cock of the coolant supply pipe 15 is opened and the cooling nozzle 1 is opened.
Coolant R is injected from step 4.

In this case, the injection direction of the coolant R is horizontal and radial as described above.

Then, the injected coolant R deprives the temperature of the atmosphere (room temperature) of the secondary cooling chamber 3 of its vaporization, rapidly expands by vaporization, and becomes a large amount of low-temperature gas, which flows from the gas outlet 6 to the first
It will then be ejected into the cooling chamber 2.

This lower part waste is discharged from the upper end opening of the cooling pipe 1 while passing through the gap of the foundry sand S accumulated in the primary cooling chamber 2. Preliminary (first) cooling of the foundry sand S in the chamber 2 will be performed.

■ Next (see Fig. 3), by raising the first valve body 9 and opening the first valve hole 7, the molding sand S in the primary cooling chamber 2 is removed from the valve hole γ. It is dropped into the secondary cooling chamber 2.

Then, since the guide aperture 13 is located directly below the first valve hole 7, the molding sand S falls into the guide aperture 1 immediately after falling.
It is guided downward along the upper body surface of 3.

As a result, on the guide cone 13T side, the flowing shape of the casting sand S is formed into a cylindrical, thin-walled curtain shape.

(See also Figure 5.) This means that the coolant R injected directly below the guide cone 13 cools the foundry sand S evenly and sufficiently to the core of the foundry sand S (-40°C ± 15°C). ℃), and this cooling effect is extremely good.

■Next, when the desired amount of (secondary) cooled foundry sand S has accumulated in the second cooling chamber 3, the supply of the coolant R is stopped and the first valve hole 1 is closed. to open the second valve hole 11.

Then, the molding sand S passes through the second valve hole 11 and falls into the moisture supply chamber 4, but at this time as well, the flow shape of the molding sand S is controlled by the guide aperture 18 in the same manner as in step (2) above. It is formed into a cylindrical and thin curtain shape.

This means that the water W injected directly below the guide cone 18 is almost evenly supplied to the surface of the particles of the foundry sand R.

Note that since the atmospheric temperature in the moisture supply chamber 4 is at room temperature and the temperature of the supplied moisture is at room temperature, the foundry sand S
Although the water on the surface of the particles is cooled by the foundry sand S, it does not freeze instantaneously, and therefore, the foundry sand S falls downward in the water supply chamber 4 while maintaining its fluidity.

■ In this way, the foundry sand S passes through the sand discharge port 17 and is filled into the wooden mold (not shown), and at this point, the water on the surface of the foundry sand S particles freezes for the first time, and this freezing causes the foundry sand S to become wooden. It will automatically solidify within the mold, providing sufficient strength for cutting.

As is clear from the above description, in the present invention, the molding sand S is cooled in advance before being filled into the wooden mold, and moisture is supplied to the surface of the molding sand particles. After that, the water on the surface of the sand particles is frozen when the sand is filled into the wooden mold to form the mold, which causes the mold to collapse as with conventional green molding. There's no room left.

In addition, cooling of the foundry sand S is performed in two stages: preliminary (first) cooling and main (secondary) cooling, and the flow shape of the foundry sand S is changed in the main (secondary) cooling stage. Since the cooling is carried out in a cylindrical, thin-walled curtain, the foundry sand S is sufficiently cooled, and this cooling effect is extremely good.

Furthermore, since the molding sand filled in the wooden mold is cooled under the same conditions as the molding sand S in the mold core and the molding sand S on the mold surface, moisture content on the surface of the molding sand S increases. When freezing, water is expected to have the same freezing ability regardless of whether it is on the surface or the core of the mold.

In addition, it promotes the fluidity of the foundry sand when filling it into the wooden mold,
Further, a surfactant may be added to the water for the purpose of adjusting the freezing time.

That is, since the present invention exhibits the above-mentioned effects by the invention described in the claims, it is extremely useful as a method for manufacturing frozen molds.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a road body showing a recently developed freezing mold manufacturing method, Figs. 2 to 5 show an embodiment of the present invention;
4 to 4 are longitudinal cross-sectional views of the present device showing the effects of this example, respectively, and FIG. 5 is a view taken along the line X--X in FIG. 3. 2...Fourth cooling chamber, 3...Second cooling chamber, 4...Moisture supply chamber, 7...First
valve hole, 9...first valve body, 11...
Second valve hole, 12...Second valve body, 13.18
...Guide awl, 14...Cooling nozzle,
19... Moisture supply nozzle, s-s'...
- Foundry sand, R...coolant, W...moisture.

Claims (1)

[Scope of Claims] 1. Before filling the mold with molding sand, the molding sand is cooled in advance, and then the cooled molding sand is poured into the mold while supplying moisture to the surface of the sand particles. A method for making a frozen mold, characterized by filling the mold with 2. A primary cooling chamber in which a first valve hole that can be opened and closed by a valve is provided at the lower end, a second valve hole that can be opened and closed by a valve is provided at the lower end, and a right conical hole is provided directly below the first valve hole. A secondary cooling chamber is provided with an umbrella-shaped guide aperture, and a secondary cooling chamber is provided with a cooling nozzle that injects coolant horizontally and radially just below the guide aperture, and a right-cone umbrella-shaped is provided directly below the second valve hole. 1. A freezing mold making apparatus characterized in that a guide aperture is provided, and the gutter directly below the guide aperture is provided with a moisture supply chamber provided with a moisture supply nozzle that sprays moisture horizontally and radially.