JPS6236536A - Running test liquid for casting molten metal - Google Patents

Abstract

PURPOSE:To attain a better reproducibility with easy adjustability of viscosity, by making a test liquid approximated to a molten light metal in viscosity by varying the mixing ratio of water in a sodium silicate solution to use it for a visual test of the running state for casing. CONSTITUTION:A transparent plastic die 1a is placed closed on the top of a container 4a, and a sprue 2a and a pipe 3a communicating therewith is provided at the lower center of the die 1a. The cavity 12a of the same type as that of a low-pressure casting equipment is provided with a core 11a of the same type as that used in casting. A test liquid 5a is a mixture of aluminum fine powder or polystyrene particles as tracer particles with the volume ratio 30% or more of water in a sodium silicate liquid and is approximated to the molten metal in viscosity by varying the mixing rate of water. Then, a compressed air is sent through a pressure port 10a to equally press the liquid surface of the test liquid 5a during the casting and a simulation experiment is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid flow test liquid for casting, and relates to a test liquid used in fields such as simulation experiments in low pressure casting methods.

[Prior art]

Conventionally, visualization tests of the melt flow state in casting light metals such as aluminum alloys using low-pressure casting methods have involved using transparent plastic molds, injecting water mixed with tracer particles into the molds, and observing from the outside. This is done by However, with this method, the viscosity of water is different from that of molten light metal, so even if the same pressure as during casting is applied, it is not possible to faithfully reproduce the flow state of the molten metal. There is a problem in that it is not possible to accurately grasp the

By the way, this low-pressure casting method is suitable for cases where the main objective is to maintain the integrity of the casting because it casts more quietly than the general gravity casting method. Since the molten metal in the pipe is lowered by returning the applied pressure caused by solidification to zero, there is no need for a riser, so the yield is good.

In order to obtain high-quality cast products with higher soundness using such casting methods, it is necessary to design the mold and set control specifications for the pressurization rate of the molten metal. It is necessary to accurately grasp the state of the flow of hot water over time. Therefore, it is strongly desired to develop a test solution that allows simulation experiments to be performed with good reproducibility.

[The purpose of the man]

The present invention solves the problems in the above-mentioned prior art and
In order to conduct good simulation experiments of N properties, the purpose is to provide a casting fluid flow test fluid whose viscosity can be easily adjusted to have a viscosity comparable to that of /8 molten metal. shall be.

[Structure of the invention]

The present invention is characterized by a test solution mixed with tracer particles for visualizing the flow state of casting metal, in which the volume ratio of H2O in the sodium silicate solution is 30% or more. By changing the mixing ratio of H2O, the viscosity can be changed to approximate the viscosity of molten light metal7.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof.

In a general low-pressure casting device, for example, as shown in Fig. 2, a sprue 2 is opened at the center of the lower part of a mold 1, and a vibrator 3 is connected downward in communication with the sprue 2. A mold 1 is placed in close contact with the upper part of a crucible 4. The crucible 4 that stores the molten metal 5 is housed in a holding furnace 8 equipped with an iron pot 7 that has a built-in heater 6. By feeding compressed air into the crucible 4 from the pressurizing port 10 provided on the lid 9 of the crucible 4, 1 kg/cn! When the following pressure is applied, the molten metal 5 is pushed up to the vibrator 3 which is located in the center and functions as an emerging stalk.
It is configured to be gradually injected into the mold 1. In addition, in the figure, 11 is a core, and 12 is a cavity.

A stain and lesion experiment apparatus used to ascertain the flow state of the molten metal 5 during such low-pressure casting is shown in FIG. This has roughly the same configuration as a low-pressure casting device, and has a container 4a containing a test liquid 5a mixed with tracer particles 13, with a hot water 112 in the upper part and a hot water 112 in the center of the lower part.
A cavity 12 having the same type as the cavity 12 of the mold 1, and having a vibe 3a hanging down in communication with the cavity 12,
3, a core 11a of the same type as the core 11 used during casting.
A transparent plastic mold 1a provided with a mold is placed in a sealed state. Container 4 corresponding to the crucible 4 described above
Injecting compressed air from the pressurizing port 10a opened at a,
By pressurizing the liquid level of the test liquid 5a, the test liquid 5a is injected into the mold 1a so that the behavior of the tracer particles 13 can be observed from the outside.

This test liquid 5a is made by mixing water in an appropriate proportion with a volume ratio of water in the sodium silicate solution of 30% or more so that the viscosity of iA 5, which varies depending on the composition and temperature, can be sufficiently approximated. Then, as tracer particles, for example, fine aluminum powder or polystyrene particles, which will be described later, are mixed. Note that the volume ratio of water in the sodium silicate solution is 30
% or more because if it is less than this, the sodium silicate solution cannot be kept in a stable state without vitrification.

Generally speaking, in order to apply the law of similarity to the motion of viscous fluids, the second reason is that not only the shapes of the objects are similar without affecting the flow of the fluid, but also the Reynolds number Re = V L
It is desirable that /ν (-ρVl-/μ) be equal.

In addition, ■=Representative flow velocity ■-: Representative length, C: Kinematic viscosity coefficient, ρ: Original fluid density, μ: Static viscosity coefficient.

In the simulation experiment, cavity 123
The shape of the core 11a is formed to be the same as that during casting, and the pressure applied to the test liquid 5a can be set to be equal to that during casting, so that {circle around (2)} and L can be made equal to those during casting. Therefore, in order to faithfully reproduce the flow of the molten metal 5 and apply the above law of similarity, the kinematic viscosity coefficient ν of the test liquid 5a may be made to match that of the molten metal 5.

This test liquid 5a is prepared by mixing various proportions of water in various sodium silicate solutions, as explained below.
A kinematic viscosity coefficient equivalent to that of the molten metal 5 of light metal such as aluminum alloy can be obtained.

In Figure 3, line A is No. 1 (H20 content 30-40
Volume %), B is No. 2 (H20 content 40-50 volume %)
, C is the change in kinematic viscosity coefficient with temperature change in each No. 3 (H20 content 50 to 60 volume %) sodium silicate stock solution, and each kinematic viscosity coefficient value changes over a range of 500 to 5000 centipoise. . By appropriately mixing water with this sodium silicate stock solution, the kinematic viscosity coefficient can be changed over a wider range.

The No. 3 sodium silicate stock solution with a high water content in the stock solution above is
It contains 50 to 60% water by volume, and for example, as shown in Figure 4, by sequentially adding and mixing water at a measurement temperature of 20°C, the kinematic viscosity coefficient can be changed from 120 centipoise to 1.
It can be varied up to centipoise. Therefore, by mixing an appropriate amount of water with this No. 3 sodium silicate stock solution, it is possible to
A mixed liquid having a value equal to the kinematic viscosity coefficient of I-13%Si alloy within the range of 590 to 800°C can be obtained.

For example, the kinematic viscosity coefficient of pure aluminum molten metal at 750°C is 1.5 centipoise, as shown in Figure 5.
In order to obtain such a kinematic viscosity coefficient, it can be seen from FIG. 4 that water is added to the No. 3 sodium silicate stock solution at a temperature of 20° C., and the volume percent of the added water is 80%.

That is, add 4 times as much water as the No. 3 sodium silicate stock solution.

Further, the kinematic viscosity coefficient of the AI-13%Si alloy is as shown below.

Thus, for example, 600°C of AI-13%Si alloy
In order to obtain a kinematic viscosity coefficient of 25 centipoise at 25 centipoise, the volume percent of water added should be 20% at a temperature of 20° C., as shown in FIG.

The specific gravity of a liquid mixture made by mixing water is approximately 1.7 or less, and when aluminum powder is used as tracer particles, its specific gravity is 2.7, which is higher than that of the liquid mixture. It becomes heavy. However, since the aluminum powder is a sufficiently small piece of powder, the sedimentation rate in the fluid based on gravity and inertia is sufficiently small, so the above-mentioned difference in specific gravity does not pose much of a problem. In addition, polystyrene particles have a ratio of M1゜05 and are slightly lighter than the mixed liquid, but if they are mixed into the mixed liquid and stirred appropriately before use, they will float with the fluid at least during simulation experiments and become tracers. It functions well as a particle.

By the way, when the molten metal 5 is poured into the mold 1, the temperature of the molten metal 5 decreases for a while, but as the temperature changes, the value of the kinematic viscosity coefficient of the molten metal 5 also changes as described above. Therefore, in order to conduct a simulation experiment with good reproducibility, the test liquid 5a must be prepared so that the value of the kinematic viscosity is equal to the value of the kinematic viscosity at the time when the molten metal 5 is injected into the mold 1. For example, as mentioned above,
Such demands can be met by a simple method of mixing water in an appropriate ratio to the sodium silicate stock solution as needed.

〔Effect of the invention〕

As can be seen from the description of the above embodiments, the present invention changes the viscosity of the test solution mixed with tracer particles by changing the mixing ratio of water in the sodium silicate solution. By preparing the test liquid so that it is equal to the kinematic viscosity coefficient, it is possible to conduct a simulation experiment that faithfully reproduces the flow of molten metal.

In addition, the specific gravity of the test liquid is greater than that of conventional water, and the sedimentation rate of the tracer particles is reduced, so its behavior becomes stable and a more realistic flow of hot water can be observed.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a simulation experiment apparatus to which the present invention is applied, Fig. 2 is a cross-sectional view of an example of a low-pressure casting apparatus, and Fig. 3 shows the behavior of No. 1 to No. 3 sodium silicate stock solutions with respect to temperature changes. Graph showing changes in viscosity coefficient, Figure 4 is at 20℃
Fig. 5 is a graph showing changes in the dynamic viscosity coefficient by adding water to No. 3 sodium silicate stock solution, and Fig. 5 is a graph showing changes in the static viscosity coefficient and dynamic viscosity coefficient of pure aluminum with respect to changes in temperature. 5--Molten metal, 5a-Test liquid, 13--Tracer particles.

Claims (1)

[Claims] (1) In order to conduct a visualization test of the flow state of molten metal for casting,
In the test solution mixed with tracer particles, the volume ratio of H_2O in the sodium silicate solution is set to 30% or more, and the viscosity is changed by changing the mixing ratio of H_2O to approximate the viscosity of light metal molten metal. Molten metal flow test liquid for casting.