JPH0139864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a technique for improving the pouring mechanism of a mold casting machine used for casting aluminum or the like.

(Prior Art) Conventionally, in a pouring mechanism for pouring molten metal such as aluminum into a casting machine, manual labor,
Alternatively, the molten metal injected by a cup or a ladle of an automatic pouring machine flows into the cavity through a passage or a passage on a saucer.

(Problem that the invention aims to solve) In this pouring mechanism, since the inner surface of the molten metal passage is generally made of metal, the heat of the molten metal is removed from the inner surface of the molten metal passage while the molten metal is being poured into the cavity. , forming a thin solidified piece of molten metal on the inner surface of the molten metal passage. This thin solidified piece accumulates and becomes thicker each time molten metal is injected, and may even become a thicker solidified piece. In either case, the solidified pieces may fall to the cavity side during mold opening, causing boiling and mold damage. Further, if the solidified pieces do not fall, the molten metal flows down over them, so that the solidified pieces are successively stacked and become thicker, and the molten metal passage becomes blocked after several tens of shots. The amount of solidified pieces formed in the molten metal passage is 2 to 5 g per shot, and several tons of metal material are wasted every year. Furthermore, since the solidified pieces are thin, they have many oxidized parts and are difficult to recycle.

In order to prevent this, various measures have been taken in the past. For example, a method has been used in which the metal body forming the inner surface of the molten metal passage is heated with a gas burner, but this method has the following drawbacks.
Gas burner heating is not sufficient. This consumes a large amount of gas and increases costs. The metal surface is heated to a high temperature, and the molten metal causes erosion.

The present invention was made to solve the problems of conventional pouring mechanisms, and provides a mold casting machine that can prevent the accumulation of solidified pieces at the pouring spout without heating the heat insulating layer. That is.

(Means for Solving the Problems) The structure of the present invention is such that the inner surface of the molten metal passage in the spout is made of a metal material or a ceramic member, and a recess is provided on the inner surface of this member so that the molten metal accumulates.
Moreover, it is characterized in that a heat insulating layer is formed on the outside of the metal member or ceramic member.

In the present invention, it is preferable that the thickness of the metal member or ceramic portion through which the molten metal flows is formed to be thin, and that the shape thereof is formed into a frame shape. This is to reduce the amount of heat melted in the metal member or ceramic member itself, and to minimize the amount of heat transmitted from the molten metal to the member. The recess provided in the metal member or ceramic member may be either a hole or a groove, and the lower part of the recess may be formed in a heat insulating layer. The recesses may be any location as long as a portion of the flowing molten metal collects therein, and the number of recesses is also arbitrary. When a recess is provided in the center of a metal member or a ceramic member in the direction of flow of the molten metal, one recess is sufficient if the cross-sectional shape is carefully designed.

The insulation layer is made of ceramics with low thermal conductivity,
For example, Al ₂ O ₃ , SiC, ZnO, Si ₃ N ₄ , C, BeO,
ZrO ₂ etc. can be used. Usually, a sleeve-shaped metal structure is disposed outside the heat insulating layer, and the pouring spout is constructed from a three-layer structure consisting of both of these and the metal member or ceramic member. In this case, a space layer may be formed between the outer sleeve-shaped metal structure and the inner metal member or ceramic member, and this may be used as a heat insulating layer. It is also possible to have a double structure consisting of layers, and in this case the insulation effect will be even greater.

The present invention suppresses the growth of solidified pieces by improving the structure of the pouring mechanism itself. In particular, the present invention is a vertical type with a short molding cycle time, which is equipped with a plunger that tightens the pouring spout and a plunger that pressurizes the molten metal. This is conveniently applied to casting machines.

(Function) Metal member or ceramic member (hereinafter referred to as metal member, etc.) constituting the inner surface of the molten metal passage of the present invention
is at a low temperature before pouring the molten metal. When molten metal is injected into this, the heat of the molten metal escapes to the metal member etc. while the molten metal flows toward the cavity, and thin pieces of solidified molten metal are formed on the surface of the metal member. At the same time, a part of the molten metal enters the recess of the metal member, etc., and a solidified lump of the molten metal is formed in the recess. Then, when molten metal is injected afterwards, the molten metal flows over the solidified pieces and heads toward the cavity, but in this case, the metal members etc. do not release heat due to the heat insulating layer.
Since the temperature is high due to the heat from the molten metal, new solidified pieces are not formed on top of the solidified pieces. In this way, the present invention prevents the temperature of the metal member itself from rising due to the heat of the molten metal, thereby preventing solidified pieces from being generated one after another each time the molten metal is poured. Further, since the extremely thin solidified piece formed on the metal member or the like is integrated with the solidified mass formed in the recess of the metal member or the like, it will not fall even when the mold is opened.

(Example) An example of the present invention will be described below with reference to the drawings. FIG. 3 shows a vertical pressure casting machine for producing castings by injecting molten metal such as aluminum alloy with a low melting point. 1 is an upper mold having a plunger sleeve 2, and 3 is a counter sleeve 4. In the lower mold, the plunger sleeve 2 has a plunger tip 5, and the counter sleeve 4 has a counter tip 6.
are slidably inserted into each other.

The upper die 1 is provided with a pouring mechanism 9 for pouring the molten metal 7 into the cavity 8 side. FIG. 1 is a detailed view of the pouring mechanism 9. As shown in the figure, a semi-cylindrical metal inner frame 13 is fixed to the lower inner surface of the molten metal sleeve 11, which is the outer cylinder of the molten metal passage 10, via a heat insulating coating 12, and the upper end of the metal inner frame 13 1
3a is bent downward and engaged with the upper end surface of the molten metal sleeve 11. The material of the metal inner frame 13 here is inexpensive steel, and its thickness is about 3 mm.

As shown in FIG. 2, a hole 14 into which a portion of the molten metal 7 falls is provided at the lower part of the inner surface of the central portion of the metal inner frame 13 in the longitudinal direction (flow direction B of the molten metal 7). This hole 14 is formed in a so-called reverse tapered shape, and the diameter of its upper opening is set to 3 mm or more. The reason why the diameter of the opening at the upper end of the hole 14 is set to be 3 mm or more is because if the diameter is less than 3 mm, it will be difficult for the molten metal 7 to enter the hole 14. In addition, hole 1
Although the shape of 4 is an inverted tapered shape in order to improve the adhesion of the solidified pieces 15 formed on the inner surface of the metal inner frame 13, the shape is not limited to this, and may be formed in a stepped shape, for example.

The material of the heat insulating coating film 12 attached to the entire outer surface of the metal inner frame 13 is not limited to neuceramics as long as it has heat insulating properties. In this embodiment, bamiyulite, which is a mold coating agent, is used as the material for the heat insulating coating film 12.

Regarding the operation of the pouring mechanism consisting of the above configuration,
This will be explained with reference to FIGS. 4 to 7. Before pouring the molten metal 7, the surface of the metal inner frame 13 remains at room temperature (FIG. 4). When molten metal is poured into this now, as shown in FIG. 5, the molten metal 7 flows while contacting the surface of the metal inner frame 13, and a thin solidified piece 15 is formed along the surface of the metal inner frame 13. At the same time, a solidified lump 16 of the molten metal 7 is formed in the hole 14 of the metal inner frame 13, integrated with the solidified piece 15. In this case, since the metal inner frame 13 is thin and has a small heat capacity, and the heat insulating coating 12 is disposed on the outside of the gold layer inner frame 13, the inner surface of the metal inner frame 13 is Heat is transferred from the flowing molten metal 7, and the temperature of the metal inner frame 13 itself reaches 500℃.
rise above.

Next, the molten metal 7 is injected again, but the molten metal 7 flows down on the solidified pieces 15 of the metal inner frame 13 (sixth
figure). Here, since the temperature of the metal inner frame 13 is heated to 500° C. or higher as described above, the molten metal 7 is
There is almost no transfer of heat from the metal inner frame 13 to the metal inner frame 13, and therefore no new solidified pieces are formed on the solidified pieces 15 (FIG. 7).

As described above, for each shot of molten metal 7,
Since the solidified pieces 15 are not stacked on the surface of the metal inner frame 13 through which the metal inner frame 13 passes, the amount of casting material used is reduced accordingly. In this case, since there is no need to heat the metal inner frame 13 from the outside, the injected molten metal 7
temperature drop is minimized. In other words, the temperature of the molten metal 7 during injection can be lowered by that amount, which greatly contributes to saving thermal energy. In fact, in this example, the pouring temperature could be lowered by 10°C. On the other hand, since the solidified pieces 15 initially formed in the metal inner frame 13 are integrally formed with the solidified pieces 16 in the holes 14, there is no risk of the solidified pieces 15 falling into the cavity side during casting, and manual labor is not required. This eliminates the need for cleaning and eliminates the problem of mold damage. Furthermore, the molten metal 7 is inserted into the metal inner frame 13.
Since the metal inner frame 13 passes over the solidified pieces 15 formed in the molten metal 7, the surface of the metal inner frame 13 is not eroded by the molten metal 7, and can be used semi-permanently.

Next, FIG. 8 is a graph showing the relationship between the number of shots of the molten metal 7 and the thickness of the solidified pieces 15 _formed on the metal inner frame 13 (plate thickness 5 mm).
is the result when no heat insulating coating 12 is provided, graph S ₂
1 and 2 respectively show the results when the heat insulating coating film 12 was provided. As is clear from this figure, when the heat insulating film 12 was not provided, the thickness of the solidified pieces 15 increased as the number of shots increased, and the molten metal passage 10 was blocked at the 76th shot. When the heat insulating coating film 12 was provided, the coagulated pieces 15 were formed only in the first shot, and the thickness of the coagulated pieces 15 did not change thereafter.

Figure 9 shows the thickness of the heat insulating coating 12 and the number of shots 10.
The relationship with the temperature of the metal inner frame 13 at the second time is shown.
As shown in the figure, when there is no heat insulating coating 12, the temperature of the metal inner frame 13 is approximately 400°C;
2, even if the film thickness is thin (for example, t ₁
= 0.2mm), the temperature of the metal inner frame 13 after 10 shots is
The temperature rose to 530°C or higher, and the growth of solidified pieces 15 could be suppressed. As the temperature of the metal inner frame 13 increased, the temperature drop of the molten metal 7 during pouring became smaller.

FIG. 10 shows the relationship between the thickness of the metal inner frame 13 and the thickness of the solidified piece 15 when the number of shots is tenth. The thinner the metal inner frame 13 is, the smaller its heat capacity is and the faster the temperature rises, which is advantageous because the solidified pieces 15 are also thinner. As is clear from the illustrated characteristics, the thickness of the metal inner frame 13 is preferably 10 mm or less.

(Effects of the Invention) As explained above, according to the present invention, the following special effects can be obtained.

The solidified pieces formed on the metal or ceramic inner frame member do not fall off when the mold is opened, so
No coagulated pieces get mixed into the cavity side,
Problems such as mold breakage and hot water blowing are eliminated, and the need for manual cleaning of solidified pieces is eliminated, greatly contributing to the automation of casting machines.

Solidified pieces only appear during the initial injection of molten metal, and unlike conventional methods, solidified pieces do not form in layers during subsequent pouring, which prevents clogging of the molten metal passage.
Moreover, the consumption of casting materials is reduced compared to the conventional method.

Since the temperature drop during pouring of molten metal is small, the pouring temperature can be lowered by that amount.
This greatly promotes energy conservation.

Since the molten metal passes over the solidified pieces instead of the inner frame member from the second injection, the inner frame member is not damaged by melting due to the molten metal, and the inner frame member can be used semi-permanently for a long period of time. .

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the structure of a pouring mechanism according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is a vertical casting according to the present invention. A sectional view showing the entire machine, Figures 4 to 7 are explanatory diagrams showing the process of forming solidified pieces in the pouring mechanism shown in Figure 1, and Figure 8 shows the relationship between the number of shots and the thickness of the solidified pieces. 9 is a graph showing the relationship between the thickness of the heat insulating coating film and the temperature of the metal inner frame, and FIG. 10 is a graph showing the relationship between the plate thickness of the metal inner frame and the thickness of the solidified pieces. 7... Molten metal, 9... Molten metal pouring mechanism, 10... Molten metal passage (pouring spout), 11... Molten metal sleeve, 12...
Heat insulating coating film (insulating layer), 13... Metal inner frame (metal member), 14... Hole (recess), 15... Solidified piece, 16
...A coagulated mass.

Claims (1)

[Claims] 1. A metal member or ceramic member is placed below the inner surface of the spout of a mold casting machine into which light metals such as aluminum, magnesium, zinc, etc. are poured, with a heat insulating layer interposed therebetween, and the molten metal flows through the molten metal passing surface of the member. A mold casting machine characterized in that a concave hole is provided for collecting and solidifying pieces and fixing solidified pieces to the surface of the member.