JPH0545346B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a casting method in which molten metal is sucked up and filled into a cavity of a mold and solidified by reducing the pressure inside the cavity.

Conventional technology The suction casting method has features such as good hot water circulation and less inclusions and air bubbles.
This is a casting method that has traditionally been used mainly when casting high-quality castings. In this method, for example, as shown in FIG.
The mold 1 is placed on a mold surface plate 2, and the mold 1 is hermetically covered by a chamber 4 having a decompression port 3.
The inside of the chamber 4 is depressurized by a vacuum pump (not shown) connected to the decompression port 3, while the stalk 6 communicated with the cavity 5 is immersed in the molten metal 8 in the melting furnace or ladle 7. As a result, the molten metal 8 is sucked up and filled into the cavity 5 through the stalk 6 due to the pressure difference between the inside and outside, and after the molten metal 8 filled in the cavity 5 solidifies, the mold 1 is taken out from the chamber 4 and the mold is dismantled. This is a method for removing castings.

Problems to be Solved by the Invention However, as is clear from the above explanation,
Since the tip of the stalk 6 is immersed in the molten metal 8, the interior of the cavity 5 is airtight and can hold the molten metal 8.
If the stalk 6 is pulled up from the molten metal 8 in the melting furnace or ladle 7 while the molten metal inside is still unsolidified,
The airtightness of the cavity 5 is broken and unsolidified molten metal flows out from the cavity 5. Therefore, conventionally, in order to prevent such a situation, the mold 1 is held above the melting furnace or ladle 7 until the molten metal in the cavity 5 is completely solidified. There was a problem in that the residence time of the mold 1 above the cast iron was increased, and the cycle time per casting was increased, resulting in poor productivity.

As a method for solving the above-mentioned problem, for example, as shown in FIG. 4, immediately after the filling of the cavity 5 with the molten metal 8 is completed, part of the molten metal in the stoke 6 is cooled rapidly. A conceivable method is to solidify the stoke 6 and use the resulting solidified mass as a plug 9 to close the stalk 6. In this way, since the unsolidified molten metal can be held in the cavity 5 by the plug 9, the mold 1 can be quickly moved from the pouring location such as above the ladle 7 immediately after filling with molten metal.

However, simply creating a plug 9 in the stalk 6 and blocking it will not only seal the cavity 5 and cut off the supply of molten metal, but also create a low pressure state, which will affect the composition of the molten metal, the size of the casting to be obtained, and the casting process. Depending on the conditions, shrinkage cavities 10 may occur as shown in FIG. 5, and this may cause a decrease in yield.

In view of the above circumstances, it is an object of the present invention to provide a suction pressure casting method that can improve productivity and yield.

Means for Solving the Problems In order to achieve the above object, the present invention reduces the pressure inside the cavity, sucks up molten metal into the cavity through a conduit such as a stalk, and fills the cavity until the filling is completed. This method is characterized in that immediately after, a predetermined part of the pipe is compressed to block it, and the compressed part is moved to the cavity side, thereby pushing the molten metal in the pipe towards the cavity side and pressurizing the inside of the cavity. .

In other words, in this invention, immediately after filling with molten metal is completed, a predetermined portion of the pipe connecting the cavity and a container such as a melting furnace is closed by squeezing, thereby preventing unsolidified molten metal from falling from the cavity. The mold can be immediately moved to the desired location, thereby reducing cycle time and increasing productivity. In addition, while solidifying the molten metal in the cavity, the pressure of the molten metal in the cavity is equivalent to that of the feeder by continuously moving the squeezing part of the pipe to the cavity side and pushing the molten metal in the pipe to the cavity side. This effect prevents the occurrence of shrinkage cavities and improves yield.

Example Examples of the present invention will be described below.

FIGS. 1A, B, and C are schematic diagrams showing the casting process according to the present invention. First, as shown in FIG. 1A,
A breathable mold 1 consisting of an upper mold and a lower mold is placed on a mold surface plate 2, and a chamber 4 is placed over it to seal it, and the sprue of the lower mold is placed on the mold surface plate 2. In this state, the inside of the chamber 4 is depressurized through the pressure reducing port 3 of the chamber 4, and the lower end of the stalk 6 is connected to the molten metal 8 in the ladle 7, for example. Soak. As a result, the cavity 5 of the mold 1 is isolated from the atmosphere, so the pressure inside the cavity 5 decreases, and the molten metal 8 is sucked up into the cavity 5 through the stalk 6 and filled with the molten metal 8. .

After the cavity 5 is filled with the molten metal 8 in this manner, the lower end of the stalk 6 is squeezed by a pair of rollers 11 to close the stalk 6, as shown in FIG. 1B. Next, while keeping the stalk 6 closed to prevent unsolidified molten metal from flowing out from inside the cavity 5, the mold 1 is moved from above the ladle 7 together with the mold surface plate 2, chamber 4, etc., and the inside of the cavity 5 is removed. solidify the molten metal.
In that case, as shown in FIG. 1C, the pair of rolls 11 that are squeezing the stalk 6 are continuously moved upward, that is, toward the cavity 5. As a result, the stalk 6 is constricted and the molten metal inside it is pushed up toward the cavity 5, so an effect equivalent to the pressure of the riser occurs on the molten metal inside the cavity 5, and as a result, the casting has a large shrinkage amount. Also, it is possible to obtain a sound casting without shrinkage cavities.

FIG. 2 is a diagram schematically showing an apparatus for carrying out the above-mentioned method, in which a pair of rollers 11 facing each other with a stalk 6 in between is arranged below the mold surface plate 2. The rollers 11 are each attached to an actuator 12 such as a hydraulic cylinder or an air cylinder, and these rollers 11 and actuator 12 are configured to move up and down along the stalk 6 and to move together with the stalk 6, mold surface plate 2, etc. There is. In the device configured in this way, for example, immediately after filling the cavity 5 with molten metal above the ladle 7, the stalk 6 is compressed and closed by moving the roller 11 forward by the actuator 12, thereby filling the inside of the cavity 5. The mold 1, together with the mold surface plate 2, chamber 4, stalk 6, etc., is moved to a predetermined cooling and solidification section while holding the unsolidified molten metal. Then, while solidifying the molten metal in the cavity 5,
By raising the pair of rollers 11 together with the actuator 12 and gradually moving the pressing part of the stalk 6 upward, the molten metal in the stalk 6 is made to act as a feeder. Therefore, according to the apparatus shown in FIG. 2, it is possible to prevent the unsolidified molten metal from flowing out from the cavity 5, and at the same time, it is possible to pressurize the molten metal in the cavity and prevent the formation of shrinkage cavities.

Effects of the Invention As is clear from the above explanation, according to the present invention, immediately after filling by sucking up the molten metal,
A predetermined part of the pipe that becomes the runner of the stalk etc. is compressed and blocked, and the compressed part is moved to the cavity side, so even if the pipe is pulled out of the molten metal, the unsolidified molten metal in the cavity is prevented from flowing out. At the same time, it is possible to pressurize the molten metal in the cavity, thereby shortening cycle time and improving productivity, and also making it possible to obtain sound castings without internal defects such as shrinkage cavities. In addition, in the method of the present invention, the molten metal in the cavity is pressurized by external mechanical operation, so the amount of riser can be reduced, which together with reducing internal defects such as shrinkage cavities, greatly increases the yield. can be improved. Further, according to the present invention, since there is no need to consider the feeder method when designing the casting method, it is possible to obtain secondary effects such as simplifying the designing of the casting method.

[Brief explanation of the drawing]

Figures 1A, B, and C are schematic diagrams showing the casting process according to the method of the present invention, Figure 2 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention, and Figure 3 is a general suction diagram. Fig. 4 is a schematic diagram showing a state in which a cavity is sucked up and filled with molten metal in the casting method, Fig. 4 is a schematic diagram showing a state in which a plug is generated in the stalk, and Fig. 5 is a schematic diagram showing a state in which shrinkage cavities are generated. . 1... Mold, 5... Cavity, 6... Stoke, 8... Molten metal, 11... Roller.

Claims (1)

[Claims] 1. The cavity of the mold placed above the molten metal is communicated with the molten metal through a predetermined pipe line serving as a runner, and the pressure inside the cavity is reduced to suck up and fill the molten metal into the cavity to perform casting. Immediately after sucking up and filling the cavity with molten metal, a predetermined portion of the pipe is compressed to block it, and the compressed portion is moved toward the cavity to push the molten metal in the pipe toward the cavity and close the cavity. A suction pressure casting method that is characterized by pressurizing the inside.