JPS5853365A - Method and device for pressure casting - Google Patents

Abstract

PURPOSE:To improve the quality and yield of castings by allowing the molten metal charged into cavities from a supply part for molten metal in a pressurized atmosphere to solidify under pressure. CONSTITUTION:A metallic mold 3 which is opened with a sprue 4 in the upper part is supported freely luffably with respect to a base plate. A receiving tray 9 for molten metal where a charging port 8 faces is supported freely oscillatably and pivotally to the upper part of the sprue 4. Further an air chamber 16 having a pressurizing chamber 15 in the upper part of the mold 3 is supported freely openably and closably to a fulcrum shaft 17. After the molten metal is supplied into the tray 9 when said chamber is opened, the chamber 16 is put on the mold 3, and compressed air is supplied into the chamber 15, by which the molten metal stored in the tray 9 is charged into cavities 5. The molten metal in the cavities 5 is solidified under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for improving the quality of cast products and the casting yield.

In general, when molten metal such as aluminum alloy or aluminum bronze comes into contact with nitrogen, an oxide film forms on the surface of the molten metal.In order to prevent this from being drawn into the cast product and to prevent the generation of air bubbles, it is necessary to place the molten metal in the mold cavity as much as possible. It is necessary to pour all the molten metal quickly and quietly. In this general gravity casting method, in the case of thin-walled castings or castings with complex external shapes, it is necessary to heat the mold to a high temperature before pouring the molten metal. Cooling time is too long and efficient casting work cannot be performed. Moreover, in this method, the volume of the sprue must be increased due to the need for a feeder action, resulting in waste of material.

For this reason, a casting method has been proposed in which, after injecting molten metal into the cavity of a mold, the mold is completely covered with a lid using a pressurized container that communicates with the cavity 1VC pressurizing chamber, and the molten metal is solidified under pressure. However, with this method, it takes time to pressurize the molten metal, so thin parts or corners solidify before pressurization, and not only can the overall pressurizing effect not be expected, but also defective products with internal stress. There are many cases where this occurs.

In order to solve the above-mentioned drawbacks, the present invention supplies compressed gas to a pressurized chamber containing a molten metal supply section (1), injects the molten metal into the cavity from the molten metal supply section in this pressurized state, and removes the molten metal in the cavity. The present invention proposes a pressure casting method and an apparatus therefor, which can improve the quality of cast products and the casting yield by solidifying the compressed gas under pressure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the pressure casting method and apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a pressure casting apparatus of the present invention, in which a mold support frame 2 is pivotally supported to a base 1 by a support shaft 2a, and this mold support 7 The frame 2 is rotated by an angle .alpha. relative to the perpendicular line as a full fulcrum of the support shaft 2a by driving the cylinder c1. Therefore, the mold 3 attached to the horizontal frame 2a of the mold support frame 2 is supported in an angularly upright and collapsed state with respect to the base 1 by the rotation of the mold support frame 2. . -In addition, cylinders C3 and C+1 are respectively installed between the vertical frame 2b and horizontal frame 2a of the mold support frame 2.
The mold 3 is opened and closed from side to side by the expansion and contraction operations of these cylinders C3 and C11. As shown in FIG. 3, the mold 3 has a sprue 4 opened upward, and a cavity 5 communicating with the sprue 4 carved in the mold 3. The sprue 4 is a cylindrical body 6 made of a heat-resistant material such as ceramic.
is fixed to the mold 3 located at the upper part of the cavity 5. A fulcrum shaft 7 is horizontally suspended on the mold support frame 2 located above the sprue 4, and a molten metal receiving tray 9 with a spout 8 facing the sprue 4 is fixed to one end of the fulcrum shaft 7.

Further, an actuation arm 10 is fixed to the other end of the fulcrum shaft 7,
A cylinder rod 12 of an air cylinder 11 is connected to the free end of the operating arm 10 by a pin 13. The base of this air cylinder 11 is connected to the horizontal frame 2a with a pin 14. Therefore, the molten metal tray 9 is driven to swing from the solid line to the imaginary line in the second figure by the expansion and contraction of the cylinder rod 12, and the molten metal held in the molten metal tray 9 flows from the spout 8 through the sprue 4. and injected into the cavity 5.

Further, an air chamber 16 having a pressurizing chamber 15 communicating with the cavity 15 via the sprue 4 is provided in the upper part of the mold 3.
is pivotally supported on a support shaft 17 so as to be openable and closable. The pressurized chamber 15
A molten metal receiving tray 9 is located in the molten metal receiving tray 9, and the molten metal receiving tray 9
The gap is large enough not to impede the operation of the machine. There is still an air cylinder 18 on the upper side of the air chuck 16.
cylinder rods 19 are connected by pins 20. The base of this air cylinder 18 is connected to the horizontal frame 2a with a pin 21. Therefore, by the expansion M operation of the cylinder rod 19 of the air chamber 161d,
It is opened and closed from the virtual line shown in the second figure to the solid line shown. Further, on the ceiling 22 of the air chamber 16, there is a hose port 23 that forms an inflow 022 for completely supplying compressed gas (air, inert gas, etc.) from a compressed gas source (not shown) to the pressurizing chamber 15; The gauge dam opening 24 for detecting the full sealed pressure in the pressure chamber 15 is fixed. Also,
A sealing member ts4 made of a single bar of ceramic material is interposed at the joint between the air chamber 16 and the mold support frame 2 in order to maintain the airtightness of the pressurizing chamber 15.

A case in which pressure casting is performed using the pressure casting apparatus configured as described above will be described.

First, the mold 3 in the state shown in the first diagram is supported in a collapsed state at an angle d=i with respect to the perpendicular, as shown by the solid line in the second diagram, and as the mold 3 moves to collapse, the cylinder rod After positioning the molten metal receiving tray 9 completely horizontally at step 12 and opening the air chamber 16 using the cylinder rod 19, molten metal is supplied to the molten metal receiving tray 9. Then, the air chamber 16 is placed over the mold 3 using the cylinder rod 19, and the cavity 1 is closed.
Compressed gas is supplied into the pressurizing chamber 15 connected to the cavity 5 to pressurize it, and the molten metal X is injected into the cavity 5 by rotating the molten metal receiving tray 9 using the cylinder 1ivc. Next, after the supply of the molten metal is completed, solidification is completed in a state where the cylinder is rotated by one rotation as shown in FIG.

Therefore, according to the present invention, since the molten metal is injected from the molten metal receiving tray 9 into the cavity while supplying compressed gas into the pressurizing chamber 15, the pressurizing time in the pressurizing chamber 15 can be shortened. Solidification is still complete from the start of pouring into the cavity 1
During the process, all of the molten metal is pressurized with compressed gas, so the molten metal inside the cavity quickly and reliably circulates through the thin-walled parts and corners, improving sprueability and ensuring good reproducibility of the cavity shape. becomes. By forming the trench sprue 4 with a heat-resistant material such as ceramic, the sprue-receiving part formed in the sprue 4 is solidified last, so that the unsolidified molten metal is preferentially forced to flow into the solidification contraction part. By improving the feeder performance and preventing the occurrence of shrinkage cavities, manufactured products without internal defects can be obtained. moreover,
Since the molten metal can be solidified under pressure, there is no need to suppress the weight of the molten metal at the conventional sprue, so the volume of the sprue can be reduced, and the amount of molten metal at the sprue can be reduced, reducing material waste. It can be omitted. Furthermore, since the molten metal solidifies under full pressure, the adhesion between the mold and the molten metal is improved.
The efficiency of heat transfer to the mold is improved, resulting in efficient cooling, and by reducing the amount of feeder in the final solidification section, the solidification time is shortened, making it possible to shorten one casting cycle, and furthermore, the injection of molten metal is Since the mold 3 is laid down at this time, the molten metal is injected along the inner wall of the sprue 4, so the molten metal does not ripple.
This elimination of air bubbles in the cast product, as well as the improvement in sprueability and pourability, makes it possible to create hot water locations that were previously considered impossible, and the range of casting methods is widened by increasing the degree of freedom in casting methods. It produces new effects such as

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the casting apparatus of the present invention, Fig. 2 is an enlarged cross-sectional view of the same essential parts and shows the mold in a collapsed state, and Fig. 3 shows the mold in an upright state. FIG. 1... Base, 3... Mold, 4... Sprue, 5...
〒Yaviti, 9... Molten metal receiver [11, 1, 5,... Pressure chamber, 16... Air chamber.

Claims (3)

[Claims] (1) A pressurized chamber communicating with the sprue of cavity 1 of the mold is provided, compressed gas is supplied to the pressurized chamber, and in this pressurized state, molten metal is introduced into the cavity from the molten metal supply section built into the pressurized chamber. supply 1
/, A pressure casting method in which the molten metal in the cavity is then solidified under pressure of compressed gas. (2) A mold with a spout opened at the top is supported on a base so that it can be raised and lowered, a molten metal receiving tray with a spout is pivotally supported on the top of the sprue, and the mold 1. A pressurized casting apparatus, characterized in that an air chamber is provided in the upper part of the molding apparatus, the air chamber having a pressurized chamber which can house a sprue tray and which communicates with the cavity through the sprue, the air chamber being fully openable and closable. (3) The pressure casting apparatus according to claim 2, wherein the sprue is made of a heat-resistant material such as ceramic.