JPH01143751A - Low-pressure casting device and casting method thereof - Google Patents

Abstract

PURPOSE: To improve product quality by dividing a stalk to a stationary stalk and a moving stalk, forming a valve and a valve seat part at butt ends and supplying inert gas to the upper part of molten metal at the time of descending of the moving stalk. CONSTITUTION: The stalk 7 is divided to the stationary stalk 9 and the lower moving stalk 10. The valve seat part 12a and the valve part 12b are disposed at their respective ends. Further, bellows 17 is installed between the cover plates of a crucible 8 on the outer periphery of the stalk 10. When the melt surface of the molten metal M exists in the stalk 10, the inert gas B is supplied to the upper part of the molten metal via the aperture between the valve 12b and the valve seat 12a. The valve 12b and the valve seat part 12a are closed and the molten metal is injected into a cavity 6 when the molten metal is risen by the pressurization of the innert gas A. As a result, the oxidation of the molten metal is surely prevented and, therefore, the product quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-pressure casting apparatus that pressurizes molten metal heated in a crucible to form it in a cavity, and a method for manufacturing the same.

[Conventional technology]

In conventional low-pressure casting equipment, wJ is connected to the bottom of the mold.
A known method is to connect an inert gas supply pipe to the field supply stalk and supply the inert gas to the top of the molten metal in the stalk to prevent the formation of oxides and oxidative combustion. Before the workpiece is sufficiently solidified,
There is a risk that the molten metal in the chamber may solidify first or the casting function may stop due to gas leakage from the inert gas supply pipe.
There is one shown in Publication No. 4850.

This technology involves forming a plurality of thin air passages in the circumferential direction at the lower end of the member forming the sprue, opening at the circumferential surface of the sprue, and connecting an inert gas source to an inert gas inlet that communicates with these air passages. Inert gas is supplied through the thin air passage.

[Problem that the invention seeks to solve]

However, in the above-mentioned method, no matter how thin it is, the ventilation passage is opened in the passage for the molten metal, and when the molten metal is injected into the cavity, the supply of inert gas is stopped, so the molten metal enters the ventilation passage. There was a risk that the ventilation path would be blocked.

The present invention was made against the background of the above circumstances, and an object of the present invention is to provide a low-pressure casting device and a method for manufacturing the same that can prevent molten metal from entering the inert gas supply path and produce good workpieces. There is.

[Means for solving problems]

In order to achieve the above-mentioned object, the low-pressure casting apparatus of the first invention pressurizes the molten metal stored in the crucible to rise in the stalk, and fills the molten metal into the cavity of the mold placed in the upper part of the stalk to form the mold. In a low-pressure casting apparatus for performing this process, the stalk is divided into an upper fixed stalk and a lower movable stalk, and the abutting ends of both stalks form a valve part and a valve seat part, and the valve part and the valve seat part are separated. is surrounded by a sealing means, and an inert gas supply pipe is connected to the sealing means for supplying an inert gas to the upper part of the molten metal through an opening between a valve part and a valve seat part that are separated when the movable stalk is lowered. The low-pressure casting apparatus of the second invention is characterized in that the molten metal stored in the crucible is pressurized to rise in the stalk, and the molten metal is filled into a cavity of a mold placed in the upper part of the stalk to perform molding. In casting tiffi, the stalk is divided into an upper fixed stalk and a lower movable stalk, a spherical valve portion and a valve seat are formed at the butt ends of both stalks, and the upper end of the movable stalk is formed into a spherical valve portion and a valve seat portion. A bellows covering the movable stalk is provided between the part and the crucible, and a sealing means surrounds the valve part and the valve seat part, and the sealing means includes a valve part that separates when the movable stalk is lowered. It is characterized in that an inert gas supply pipe for supplying inert gas to the upper part of the molten metal is connected through the opening between the valve seats.

In addition, the low-pressure casting method of the third invention is a low-pressure casting method in which the molten metal stored in the crucible is pressurized and raised in the stalk, and the molten metal is filled into a cavity of a mold placed in the upper part of the stalk to perform molding. The stalk is divided into an upper fixed stalk and a lower movable stalk, and the butt ends of both stalks are used as a valve part and a valve seat part, and the valve part and valve seat are separated when the movable stalk is lowered. An inert gas supply pipe is connected to the opening between the seats, and after the level of the molten metal that has finished filling the cavity descends into the interior of the movable stalk, the inert gas supply pipe is passed through the opening to the upper part of the molten metal. During molding when the molten metal rises, the movable stalk is raised to close the opening between the abutting ends and stop the supply of the inert gas.

[For production]

The movable stalk descends when the molten metal level is within the movable stalk to open the space between the valve part and the valve seat, and supplies the inert gas supplied from the inert gas supply pipe to the inside of the sealing means to the valve part. The molten metal is supplied to the upper space through the opening between the valve seats and the air inside the space is purged.

Also, when the molten metal rises or falls within the stalk,
The movable stalk is raised to close the opening and shut off the inside and outside of the stalk, stopping the supply of inert gas and allowing the flow of molten metal.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The low-pressure casting apparatus 1 includes a mold 5 consisting of a fixed mold 3 and a movable mold 4 arranged on a bed plate 2. The mold 5 is disposed below the fixed mold 3.
The upper end of a vertical stalk 7 communicating with the inner cavity 6 is connected, and the lower end of the stalk 7 is immersed in molten IM of aluminum alloy or the like heated and stored in a crucible 8.

The stalk 7 is divided into an upper fixed stalk 9 whose upper end is connected to the fixed mold 3 and a lower movable stalk 10, and a seal 11 is provided around the lower end of the fixed stalk 9 which is the abutting end. The upper end of the movable stalk 10 is made into the valve seat part 12a, and the joint surface has a length J with a radius in order to improve the joining property and centering of both stalks 9 and 10. It is formed by a part of the downward spherical surface G.

At the upper end of the movable stalk 10, an upper ring 14 and a lower ring 15, whose peripheral edges are held between clamps 13, are provided with seven flange 10a sandwiched between them. 8 cover plate 1
6, a bellows 17 and a guide ring 18 are provided inside and outside.

The bellows 17 has an opening 16a in the cover plate 16.
It communicates with the Lupo 8 through which it passes, makes the outer periphery of the movable stalk 10 the atmosphere of the crucible 8, maintains the temperature inside the movable stalk 10, and expands and contracts as the movable stalk 10 moves up and down.

In addition, an operating lever 19 for vertically moving a movable stalk 1° is pivotally supported on the guide ring 18, and its lower end is fitted into the guide 1i116b of the cover plate 16 to connect the valve seat portion 12a and the valve portion 12b. Sometimes the guide groove 16
The upward movement of the movable stalk 10 guided by b and the bellows 1
Due to the restoring force of 7, the fixed and movable stalks 9 and 1o can be centered more accurately.

At the bottom of the fixed stalk 9, there are a small diameter 7 flange 9a and a large diameter 7
A small-diameter 7 flange 9 disposed on the inner periphery of the upper ring 14 near the valve seat portion 12a.
A plurality of through holes 20 are formed in the upper outer periphery of the hole 20.
A stop ring 14a extending around the inner circumference of the upper ring 14
The moving group of the movable stalk 10 is set by the gap C between the stop ring 14a and the small diameter flange 9a, and the lower limit is defined by the contact between the stop ring 14a and the small diameter flange 9a. &+1 is given.

A bellows 21 is provided between the large diameter 7 flange 9b and the upper ring 14 so as to surround the fixed stalk 9, so that a bellows 21 is provided between the large diameter 7 flange 9b and the valve seat portion 12a and the valve portion 12b. , a sealing means 22 is constructed.

A pressure circuit 23 is connected to the crucible 8, a supply circuit 24 is connected to the sealing means 22, and a displacement circuit 25 is connected to the mold 5.

The pressure circuit 23 is connected to the WJ heated and stored in the crucible 8.
It supplies inert gas A under pressure to fill the cavity 6 with WM from the stalk 7. A pressurizing device 28 is interposed in the pipe 27 connected to the inert gas supply source 26, and The opening is provided above the melt 111M in the crucible 8.

The supply circuit 24 is designed to prevent air from entering the space above the molten metal level and mixing into the molten metal M when the level of the molten metal IM in the stalk 7 descends into the movable stalk 10. Activated gas B is supplied, and since this inert gas B comes into contact with the atmosphere, an inert gas material having a higher antioxidant effect than inert gas A is used.

The end of the inert gas supply piping 29 for feeding the inert gas B is opened from the large diameter 7 flange 9b of the fixed stalk 9 to the sealing means 22, and the inert gas The inert gas B supplied from the supply source 30 is dissolved in
A heat exchanger 31 is installed to raise the temperature to about 400°C to 600°C, which is close to 400°C to 600°C.

Further, the displacement circuit 25 promotes the inflow of the inert gas B supplied from the supply circuit 24, and sucks and exhausts air remaining in the upper space and the cavity 6 in order to create a higher-density gas atmosphere therein. Piping 34 connects the vacuum pump 33 driven by the motor 32 and the mold 5.
A heat exchanger 35 is interposed therein.

Since the air sucked from the stalk 7 and the cavity 6 reaches a high temperature of about 400°C to 500°C, this heat exchanger 35 lowers this air to about 0°C to 30°C, which is about room temperature, and vacuums it. Provided to protect the pump 33.

Next, the operation of this embodiment configured as described above will be explained with reference to the time chart of FIG.

The molten metal M17) inside the stalk 7 is located inside the movable stalk 10 and melts into the cavity 6! When clamping the mold 5 which is not filled with iiM, the movable stalk 10 is at the lower limit position where the stop ring 14a contacts the small diameter 7 flange 9a, and the space between the valve seat portion 12a and the valve portion 12b is open and there is no problem. The inert gas 8 from the active gas supply pipe 29 is continuously supplied to the upper space of the molten IM and the cavity 6 through the opening 20 of the sealing means 22.

When the replacement circuit 25 is turned on with the supply of inert gas B,
The movable stalk 10 moves upward, and the valve portion 1 is attached to the valve seat als12a.
2b is seated to cut off the supply of inert gas B, the supply circuit 24 is turned off, and emptying is performed in which residual air and inert gas B are discharged from the cavity 6.

Next, the pressurizing circuit 23 is ONL, and an inert gas is supplied to the crucible 8, and the liM in the crucible 8 is injected into the cavity 6 from the stalk 7, completing filling and solidification.

And 1! ) After the hardening is completed, turn off the pressure circuit 23.
When the pressurized supply of inert gas A is stopped, the molten IM separated from the lower end of the fixed mold 3 moves down inside the stalk 7, completes exhaustion, and the scene of the molten IM changes to the movable stalk 10.
When the movable stroke 10 is lowered, the valve seat portion 12 is lowered.
A and the valve part 12b are opened, and the supply circuit 24 is ONL/
Then, the inert gas 8 is supplied to the upper space of the molten sM through the opening 20 of the sealing means 22.

The inert gas B is continuously supplied even when the mold 5 is released and the workpiece W is taken out from the cavity 6.
This prevents air from entering the molten AM, and the mold is opened after the workpiece W is taken out to complete one molding step.

Therefore, when pouring the molten metal, the valve seat part 12a and the valve part 12b, which serve as inert gas supply ports, are closed and the molten metal is poured into the molten metal.
This prevents the intrusion of gas and secures an inert gas supply path, thereby preventing the formation of oxides and oxidative combustion, making it possible to obtain good workpieces.

Further, in the above embodiment, the displacement circuit 25 is connected to the cavity 6 to exhaust the residual air in the cavity 6 and the upper space to increase the filling density of the inert gas B, but especially in the first molding. During molding, it is effective in discharging the air remaining in the cavity 6, and during the second and subsequent molding, the inert gas B is discharged from the upper space of the stalk 7 to the fixed mold 3, preventing air from entering. Although the suction by the displacement circuit 25 is not necessarily required, the supply circuit 2
This does not preclude its use in combination with 4.

In addition, the valve part and valve seat part of the Kinomi quasi-example are opposite to those of the above embodiment.
It may also be formed by a portion of an upward spherical surface.

〔Effect of the invention〕

As explained above, in the first and third inventions, the stalk is divided into an upper fixed stalk and a lower movable stalk, and the butt ends of both stalks are used as a valve part and a valve seat part,
The valve part and the valve seat part are surrounded by a sealing means, and an inert gas is supplied to the upper part of the molten metal through the opening between the valve part and the valve seat part, which are separated when the movable stalk is lowered. When the inert gas supply pipe is connected and molten metal is injected into the opening, the valve part and valve seat are closed by connecting both stalks, and the inert gas supply is stopped to ensure smooth flow of the molten metal. At the same time, when the pressurization of the molten metal is released, inert gas is supplied from the opening between both stalks to the space above the molten metal inside the stalk, so that the molten metal does not enter the inert gas supply path. oxidation of the molten metal is ensured, and a good workpiece can be obtained.

Further, in the second invention, in addition to the structure of the first invention, a spherical valve part and a valve seat part are formed at the abutting end of the fixed stalk and the lower movable stalk, and the movable stalk is... Since a bellows covering the movable stalk is provided between the upper end of the crucible and the crucible, it is possible to improve the centering and connection between the fixed stalk and the movable stalk that moves up and down.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, in which Fig. 1 is a cross-sectional front view of essential parts of a low-pressure casting device, Fig. 2 is a system diagram in which a pressure circuit, a supply circuit, and a displacement circuit are connected to the low-pressure casting device, and Fig. 3 The figure is a time chart. 1...Low pressure casting device 3...Fixed type 4...
Movable mold 5... Mold 6... Cavity 7
... Stoke 8... Crucible 9... Upper fixed stalk 9a... Small diameter 7 langes 9b... Large diameter flange 10... Lower movable stalk 12a.
...Valve seat part 12b...Valve part 14...Upper ring 14a...Stop ring 16...Cover plate 17...Bellows 18...Guide ring 20...Through hole 21... Bellows 22
... Sealing means 23 ... Pressure circuit 24 ... Supply circuit 25 ... Replacement circuit 26.30 ... Inert gas supply source 29 ... Inert gas supply piping A, B
...Inert gas C...Gap between stop ring 14a and small diameter 7 flange 98 D...Upper space G
... Spherical surface M ... Molten metal J ... Radius length boat I factor

Claims (1)

[Scope of Claims] 1. In a low-pressure casting device that pressurizes molten metal stored in a crucible and raises it in a stalk, and performs molding by filling the molten metal into a cavity of a mold placed above the stalk, the stalk is divided into an upper fixed stalk and a lower movable stalk, the abutting ends of both stalks are used as a valve part and a valve seat part, and the valve part and the valve seat part are surrounded by a sealing means, and the valve part and the valve seat part are surrounded by a sealing means. A low-pressure casting apparatus characterized in that an inert gas supply pipe is connected to the sealing means to supply an inert gas to the upper part of the molten metal through an opening between a valve part and a valve seat part that are separated when the movable stalk is lowered. 2. In a low-pressure casting device that pressurizes the molten metal stored in a crucible and causes it to rise through the stalk, filling the molten metal into the cavity of a mold placed above the stalk to perform molding, the stalk is connected to an upper fixed stalk. a lower movable stalk, a spherical valve portion and a valve seat are formed at the abutting ends of both stalks, and a bellows covering the movable stalk is provided between the upper end of the movable stalk and the crucible. At the same time, the valve portion and the valve seat portion are surrounded by a sealing means, and the sealing means is provided with an inert gas to the upper part of the molten metal through an opening between the valve portion and the valve seat portion that are separated when the movable stalk is lowered. A low-pressure casting device characterized in that an inert gas supply pipe for supplying gas is connected. 3. In a low-pressure casting method in which molten metal stored in a crucible is pressurized to rise in the stalk and the molten metal is filled into a cavity of a mold placed above the stalk to perform molding, the stalk is connected to an upper fixed stalk. The lower movable stalk is divided into two parts, and the butt ends of both stalks are used as a valve part and a valve seat part, and an inert gas supply pipe is connected to the opening between the valve part and the valve seat part, which are separated when the movable stalk is lowered. After connecting and filling the cavity, the level of the molten metal falls into the movable stalk, and then inert gas is supplied from the inert gas supply pipe to the upper part of the molten metal through the opening, and the molten metal rises. A low-pressure casting method characterized by raising a movable stalk during molding, closing the opening between the butt ends, and stopping the supply of inert gas.