JPH02133159A - Molten metal pouring device for die cast molding - Google Patents

Abstract

PURPOSE:To decrease the generation of blowholes in a die cast product by forming a gas discharge part which communicates the inside and the atm. to the upper position of a cylindrical member nearer the die than the pouring port thereof. CONSTITUTION:The molten metal pouring device for die cast molding is constituted of the cylindrical member 1 and a piston 3 which is housed freely slidably into the member. One end of the member 1 is connected to a runner 6 of the die 5 for die cast molding. The pouring port 2 communicating with the inside is opened to the upper part of the side face thereof. The gas discharge part 8 which communicates the inside and the atm. is, thereupon, formed to the position of the member 1 nearer the die 5 than the pouring port 2 thereof. The amt. of the gas in the molten metal pouring device to be intruded into the molten metal is minimized by the gas discharge part 8 at the time of pouring of the molten metal into the die 5. The generation of the blowholes in the die cast product is decreased in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a molten metal injection device used for die-casting, and particularly relates to a molten metal injection device used for die-casting, and in particular, irregular voids (hereinafter referred to as
Pertaining to something that spawns a nest (called a nest).

[Prior Art] An example of a conventional molten metal injection device is shown in FIG. Cylindrical member 1
An injection port 2 is provided at the upper side of the mold, and a piston 3 is slidably housed inside the mold to push the molten metal 4 injected from the injection port 2 toward the mold 5. The tip of the cylindrical member 1 is connected to a runner 6 of a mold 5, and the inlet portion of the runner 6 forms a sump 7 with a larger opening.

[Problems to be Solved by the Invention] By the way, a large number of cavities inevitably occur inside die-cast products. As a result of intensive research into the cause of this occurrence, the inventor of the present invention has discovered that there is a problem with the above-mentioned molten metal injection device. That is, when the molten metal 4 is injected, combustion gas of the lubricating oil and gas generated from the molten metal 4 itself are generated in the cylindrical member l, and this gas is pushed by the piston 3 and moves together with the molten metal 4 toward the mold 5. The air is degassed through the runner 6. However, the molten metal 4 that has entered the pool 7 is cooled on the mold surface, making the flow relatively slow and obstructing the passage of gas in the runner 6. For this reason, these gases are mixed into the molten metal 4 near the inlet of the runner 6, and are then forced into the mold 5 together with the molten metal 4 with insufficient gas-liquid separation.
This results in the formation of nests in the product.

Therefore, an object of the present invention is to prevent such gas from being mixed in, and
An object of the present invention is to provide a molten metal injection device that can reduce the occurrence of cavities.

[Means for Solving the Problems] In order to solve the above problems, the molten metal injection device for die casting molding according to the present invention includes a gas that communicates the interior with the atmosphere at an upper position closer to the mold than the injection port of the cylindrical member. It is characterized by forming a discharge part.

[Operation of the Invention] When molten metal is injected into the cylindrical member and pushed toward the mold by a piston, a portion of the molten metal closes the inlet of the runner. However, the internal gas is released into the atmosphere from a gas discharge port opened in the cylindrical member near the mold. Therefore, when the piston is further pushed to force the molten metal into the mold, the amount of gas mixed into the mold is minimized, reducing the number of cavities inside the molded product.

[Example] An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

Note that the same reference numerals are used for parts common to the conventional example shown in FIG.

This molten metal injection device includes a cylindrical member 1, and an injection port 2 is formed in the upper side surface of the end portion thereof. A piston 3 is slidably housed inside the cylindrical member 1 and is configured to push a molten metal 4 made of molten aluminum injected from an injection port 2. One end of the cylindrical member 1 is connected to a runner 6 of a mold 5.

A water reservoir 7 is formed at the inlet of the runner 6 to perform gas-liquid separation.

Furthermore, a groove-shaped gas discharge part 8 as shown in FIG. 2 is formed on the upper inner surface of the cylindrical member 1 from the injection port 2 to the vicinity of the mold 5 along the direction of pitching force of the cylindrical member 1. The inside of the cylindrical member 1 is communicated with the atmosphere via the injection port 2.

The injection port 2 is formed at a position relatively distant from the mold 5 side, for example, at a position where the height of the molten metal 4 is about 20 to 30% of that when fully filled.

Further, the position of the tip of the gas discharge part 8 (the part closest to the mold 5) is, for example, about 80 degrees with respect to the height of the groove filling state of the molten metal 4.
%, and is formed at a height such that a part of the molten metal 4 enters the pool 7. However, the positions of the injection port 2 and the tip of the gas discharge part 8 can be appropriately selected depending on molding conditions and the like.

Next, the operation of this embodiment will be explained. First, the piston 3 is moved back to the solid line position in Fig. 1, and the molten metal 4 is poured into the injection port 2.
When injected into the cylindrical member 1, the molten metal 4 spreads between the piston 3 and the mold 5 at a height of, for example, about 20 to 30% when fully filled. Since the injected molten metal 4 is cooled at the contact portion with the cylindrical member 1 and the mold 5, the flow becomes relatively slow, but during this time, the lubricating oil in the cylindrical member 1 is burned to generate combustion gas. . A gas 9 consisting of this combustion gas and gas generated from the molten metal 4 itself fills the cylindrical member 1, and a portion of the gas 9 flows out from the injection port 2.

When the piston 3 is pushed in the direction of the mold 5 in this state, the surface of the molten metal gradually rises, and eventually when the tip of the molten metal 4 enters the pool 7, this part is cooled by the mold surface of the mold 5. This is a portion where the flow is relatively slow and prevents the gas 9 from passing through the runner 6 and being degassed. However, at this stage, since the gas discharge part 8 is formed at the upper part of the inner surface of the cylindrical member 1, the gas 9 compressed by the piston 3 passes from the gas discharge part 8 through the inlet 2 and flows into the cylindrical member 1. It is pushed out into the outside atmosphere. Further, push the piston 3 and move it forward while discharging the gas 9, so that the molten metal surface is in the groove filling state, for example, about 8.
When it rises to about 0%, the gas discharge part 8 is closed by the piston 3.

When the piston 3 is further pushed from this state and the molten metal 4 is forced into the mold 5, the amount of gas 9 mixed into the molten metal 4 in the sump 7 portion becomes small. As a result, the amount of gas mixed into the molded product in the mold 5 is extremely reduced, so that the occurrence of cavities inside the die-cast product is prevented to the utmost.

Therefore, when comparing die-cast products molded under the same conditions using a conventional molten metal injection device and the device of this embodiment, for example, the defect rate due to cavities is 15% in the conventional method.
However, in this example, it was possible to reduce it to 0.3%.

[Effects of the Invention] Since the molten metal injection device according to the present invention has a gas discharge part formed near the mold, it is possible to minimize the amount of gas mixed in the molten metal injection device when pressurizing the molten metal into the mold. . Therefore, the occurrence of voids in the product after molding is significantly reduced, and the defective rate due to the occurrence of voids can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the embodiment, Figure 2 is II-I of Figure 1.
The I-line sectional view, FIG. 3, is a diagram corresponding to FIG. 1 of the conventional example. (Explanation of symbols) 1... Cylindrical member, 2... Inlet, 3... Piston, 4... Molten metal, 5... Mold, 6... Runner, 7
...Hot water reservoir, 8...Gas discharge section, 9...Gas.

Claims (1)

[Claims] A cylindrical member having one end connected to a runner of a die-casting mold and having an injection port communicating with the inside at the upper side of the member, and a piston slidably housed inside the cylindrical member. A molten metal injection device for die-casting forming, characterized in that a gas discharge part is formed at an upper position closer to the mold than the injection port of the shaped member to communicate the inside with the atmosphere.