JPS5916664A - Low pressure casting device - Google Patents

Abstract

PURPOSE:To provide a low pressure casting device which can maintain a specified charging speed and feeding pressure constant by forming a stalk into a bisected construction, connecting the same to a casting mold, connecting a means for detecting pressure in the sealed space thereof and controlling a supply system for pressurized gas. CONSTITUTION:A control panel 15 for charging is operated to open a gas feed valve 13 to feed a pressurized gas to the space part in a holding furnace 1. The molten metal 7 in the furnace 1 ascends in a large diameter stalk 4 and a small diameter stalk 5 and enters the inside of a casting mold 3. The gas sealed by the molten metal 7 on the outside circumferential side of the stalk 5 is compressed into an expansion joint 6, and the pressure thereof is compared with the set value of a pressure switch 10. The opening of the valve 13 is controlled by the signal thereof, by which the gas is maintained at a prescribed pressure. The feeding pressure is made uniform by the low pressure casting device using the above-mentioned bisected stalk, whereby the quality of the product is improved. The mutual positional relation between the furnace 1 and the mold 3 is relieved and the combination of the furnace 1 are the casting machine is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-pressure casting apparatus for stably casting castings of uniform quality by constantly applying a constant pressing force as pouring progresses.

Conventionally, in low-pressure casting equipment, a mold is placed above an insulating furnace that holds a constant amount of molten metal, and the sprue of the mold and the molten metal in the insulating furnace are connected by a casting pipe, that is, a stalk, to keep the insulating furnace airtight. As a structure, the molten metal is pushed up and cast into the mold by pressurizing the space inside the heat retention furnace, but as the casting progresses, the WJmm inside the heat retention furnace decreases, so the predetermined feeder pressure cannot be obtained with a constant pressurizing force. There was a problem.

For this reason, a method is usually used to increase the pressurizing pressure in the space inside the heat-retaining furnace by a constant pressure every time it is poured.However, in the first pour after replenishing molten metal, the initial pressure is unstable and There was a problem in that the feeder pressure could not be maintained constant by increasing the constant pressure due to the adhesion of slag, etc.

Furthermore, a mold is usually composed of a metal mold, which is a large heavy chain structure including a mold opening/closing mechanism, and is set above the insulating furnace while being centered with the insulating furnace to prevent leakage. However, it has not been easy to connect the mold and the insulating furnace through a stalk, which is relatively structurally weak, from a structural and operational standpoint.

In order to solve the above problems, the present invention realizes constant casting speed and feeder pressure regardless of the amount of molten metal in the incubation furnace, and also achieves positional accuracy in setting the mold in the incubation furnace. The purpose is to ease the problem and make installation easier.

In order to achieve this object, in the low-pressure casting apparatus of the present invention, the stalk is divided into two parts, one stalk being attached to the mold side and the other stalk being attached to the insulating furnace side. In this case, the insulating furnace-side stalk has a larger pipe diameter than the mold-side stalk, and the insulating furnace-side stalk is inserted into the mold-side stalk from the upper end downward. The large-diameter stalk attached to the heat-retaining furnace side and the mold sprue are airtightly connected by an expansion joint disposed around the small-diameter stalk.

During pouring, a sealed gas space is formed on the upper surface of the molten metal between the outer periphery of the small-diameter stalk and the inner periphery of the expansion joint and large-diameter stalk. is fed back to the pressurized gas supply system. Therefore, by controlling the pressure in the closed space to be constant, constant casting speed and feeder pressure can be achieved. In addition, since the stalk is divided into two parts, the mold can be installed above the heating furnace with a misalignment within the range where the small-diameter stalk on the mold side does not interfere with the large-diameter stalk on the insulation side, which reduces positioning accuracy. This simplifies the joining process and achieves the desired purpose.

Preferred embodiments of the low pressure casting apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, 1 is a heat-retaining furnace having an airtight structure, and the upper part is covered with 11a. A mold mounting member 2 is provided above the heat retention furnace 1, and a casting mold 3 for casting is installed on this mold mounting member 2.

The lid 1a of the heat retention furnace 1 has a casting pipe hanging downward,
4 is installed. The stalk 4 is constructed from a relatively large-diameter tube. On the other hand, a relatively small-diameter stalk 5 is attached to the mold sprue of the mold 3, and the lower end of the small-diameter stalk 5 is inserted downward into the upper end of the large-diameter stalk 4. A double composite stalk consisting of the large-diameter stalk 4 and the small-diameter stalk 5 constitutes a stalk that guides the molten metal to the mold 3.

Further, an expansion joint 6 is arranged around the small diameter stalk 5. The expansion joint 6 consists of a metal bellows, for example,
The upper end flange of the large diameter stalk 4 and the mold mounting member 2 are airtightly connected.

When the molten metal 7 in the insulating furnace 1 is pushed up into the mold 3 through the stalk 4.5, the gas around the outer circumference of the small diameter stalk 5 has no place to escape, so the outer circumferential surface of the small diameter stalk 5, the expansion joint 6 and the large A space surrounded by the inner peripheral surface of the diameter stalk 4 and the upper surface of the molten metal forms a sealed space 8. A pressure detection conduit 9 opens into the sealed space 8, and the pressure in the region 8 is guided to a pressure detection device [10, for example a pressure switch 10].

4-11 is a pressurizing gas communication port to the heat retention furnace 1, and the pressurizing gas 1
Connected to 1112. An air supply valve 13 and an exhaust valve 14 are provided in the middle of the pressurizing gas piping. Reference numeral 15 is a casting control panel composed of a timer relay and the like. The signal from the pressure switch 10 is fed back to a pressurization system, for example, an air supply valve 13, and the amount of pressurized gas supplied is controlled so that the pressure in the closed space 8 is constant.

FIG. 2 shows another embodiment of the low-pressure casting apparatus according to the present invention, which differs from the previous embodiment only in the pressure control system. In FIG. 2, 16 is a pressure-voltage converter;
17 is a controller, and 18 is a pressurization pattern setting device, which is composed of a relay, a timer, a potentiometer, and the like. Here, the pressure signal converted into an electric signal by the pressure-voltage converter 16 is compared with the signal sent from the pressurization pattern setting device 18 by the controller 17, and the pressurization signal is sent to the air supply valve 13. It is now possible to send out messages.

In the low-pressure casting apparatus configured as described above, the feeder pressure is controlled as follows.

First, the air supply valve 13 is opened by the casting control 11i15 or the controller 17, and pressurized gas is sent into the internal space of the heat retention furnace 1 from the pressurization system. The molten metal 7 in the heat-retaining furnace 1 is moved up through the large-diameter stalk 4 and the small-diameter stalk 5 into the mold 3 by pressurized gas. The gas body pushed into the small diameter stalk 5 is pushed into the mold 3 and escapes from the gap in the mold 3 to the outside.

On the other hand, the gas that enters the outer circumferential side of the small diameter stalk 5 and is sealed by the melt Ii 7 is compressed into the expansion joint 6 and is compared with the set value of the pressure switch 10 or the set value of the pressurization pattern setter 18. The opening degree of the air supply valve 13 is adjusted by the controller 17 and maintained at a predetermined pressure.

FIG. 3 shows an example of pressure control characteristics, where PI indicates the pressure in the closed space 8, and PF indicates the pressure in the internal space of the heat retention furnace 1. As shown in the figure, by controlling PI to a constant pressure Pi, the feeder pressure can be kept constant for each shot, improving the quality of the product.

10,000 PF is the pressure PO added to the above PI until the molten metal reaches the small diameter slots 1 to 5, and the drop in the tide level for each shot is automatically compensated for.

In addition, when setting the mold 3 above the heat insulating furnace 1, if the small diameter stalk 5 is inserted into the large diameter stalk 4, positional accuracy is especially required in any of the front and back, left and right, and up and down directions. This eases the need for centering between the mold 3 and the heat-retaining furnace 1, making setup and installation work much easier.

As described above, when using the low pressure casting apparatus of the present invention, the following various effects can be obtained.

First, the stalk is divided into two stalks and composite polymerized,
Since the pressurization of the heat-retaining furnace is controlled by the pressure in the closed space of the area, it is possible to equalize the feeder pressure and improve the quality of the product.

Further, since the stalk 4r2 is divided into two parts, the mutual positional relationship between the heat insulating furnace and the mold is relaxed, making it easy to combine the insulating furnace 7- and the casting machine, and shortening the working time.

Since the stalk is structured in two parts, the lifting height for attaching and detaching the heat insulating furnace and mold is reduced, and equipment costs can be reduced.

Furthermore, since the stalk is divided into two parts, the structure can be simplified, which avoids applying excessive pressure to the heat insulating furnace and mold.

Furthermore, since the stalk is divided into two parts, the cost of consumable parts can be reduced and quality can be lowered, making it possible to reduce the cost of the stalk.

In general, since the outer periphery of the small-diameter stalk is blocked from air, solidification of the molten metal at the mouthpiece is avoided, and directional solidification from each part of the product to the side mouth is promoted, improving quality.

[Brief explanation of drawings]

FIG. 1 is a sectional view also showing a pressurizing system of a low-pressure casting apparatus according to an embodiment of the present invention, and FIG. 2 is a system diagram of a pressurizing system of an apparatus according to another embodiment of the present invention. Figure 3 is a pressure characteristic diagram of a pigeon holding furnace showing a pressure casting pattern. 1......Heating furnace 2...Mold mounting member 3...Mold 4...Large diameter stalk 5 ......Small diameter stroke 6...Expansion joint 7... Molten metal 8...... Sealed space 9. ...... Pressure detection conduit 10 ...... Pressure detection device 13 ...... Air supply valve 15 ...... Timer relay

Claims (1)

[Claims] (1) The stalk that guides the molten metal in the insulating furnace to the mold above the insulating furnace is divided into two parts: a large diameter stalk attached to the insulating furnace side and a small diameter stalk attached to the mold side, and the small diameter stalk is installed inside the large diameter stalk. When inserted, the large diameter stalk is airtightly connected to the mold via an expansion joint provided around the small diameter stalk, and a sealed space is formed during casting between the outer periphery of the small diameter stalk and the inner periphery of the large diameter stalk and the expansion joint. 1. A low-pressure casting apparatus characterized in that a pressure detection device is connected to the pressure detection device, and a signal from the pressure detection device is fed back to a pressurized gas supply system to a heat retention furnace to control pressurization.