JPS60130461A - Pressure casting method - Google Patents

Abstract

PURPOSE:To enable higher efficiency of a casting operation by providing a pressurizing cap for forming a pressurizing chamber on dies, holding airtightly the pressurizing cap to the dies, supplying a pressure gas to the inside of the pressurizing chamber and performing pressure casting. CONSTITUTION:Dies 11 which are divided to and constituted of plural parts are clamped and after a molten metal is poured from a riser 13 into a product cavity 12, a pressurizing cap 14 is airtightly held to the dies 11 via a packing 14a by a hydraulic cylinder 25. A valve 24 is opened to communicate a vacuum tank 22 and a pressurizing chamber 15 after prescribed time, thereby reducing the pressure in the chamber 15. The pressure decreasing is stopped before the solidification of the molten metal advances too much and at the same time a valve 23 is opened to feed the pressure gas from a compressor 19 to the inside of the chamber 15. The solidification is thus completed. The extremely highly efficient casting operation is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure casting apparatus, and more particularly to a pressure casting apparatus that can achieve high productivity and can be provided at low cost.

It is well known to cast aluminum alloys etc. using metal molds, but in this case, it is possible to prevent casting defects such as blowholes and porosity that occur in castings, and to reduce the feeder volume to improve casting yield. For the purpose of improving the quality, pressure casting method is sometimes adopted.

This pressure casting method is a casting method in which the molten metal in the solidification process is pressurized by pressurized air, and the equipment conventionally used in this casting method is as shown in FIG. 2 is arranged to guide pressurized air into the container 1 from the air supply hole 3 to pressurize the molten metal.

By the way, when performing casting using the above-mentioned device,
A mold 2 is prepared outside the pressure vessel 1, the prepared mold 2 is carried into the vessel 1, molten metal is poured in, and then the top cover 4 of the pressure vessel 1 is fixed and supply of pressurized air is started. However, after the molten metal has solidified, it is necessary to take out the casting through a process reverse to that described above, which requires a lot of work. Therefore, although the quality of the produced castings improves, the production cost increases, and as a result,
Although the pressure casting method described above has been carried out on a trial basis, the reality is that it has not yet been introduced into mass production lines.

This invention has been made in view of the above, and an object thereof is to provide a pressure casting apparatus that can perform the pressure casting method described above with high efficiency and can be manufactured at low cost.

The pressure casting apparatus of the present invention, which achieves the above object, includes a mold having an opening that opens upward, a pressure lid that covers the opening and forms a pressure chamber in the upper part, and It is characterized by having an air supply means for supplying pressurized air into the room, and a holding means for holding the pressurizing lid to the mold.

As a result of the above, pressurized casting can be performed by simply placing a pressurizing lid on the mold, holding it with a holding means, and introducing pressurized air into the pressurizing chamber, which was required in conventional equipment. This eliminates the need for loading and unloading containers and attaching and removing container lids, making it possible to carry out casting operations with extremely high efficiency. In addition, unlike conventional equipment, a large pressure vessel is not required, and only a small pressurized chamber is required.
The device is compact and therefore can be manufactured at low cost.

Next, specific embodiments of the pressure casting apparatus of the present invention will be described in detail with reference to the drawings.

In FIG. 2, reference numeral 11 denotes a mold that is divided into a plurality of parts (in the case of the figure, two parts). ,
A riser portion 13 that opens on the upper surface of the mold 11 is formed. The riser portion 13 serves as a portion for holding the riser after pouring, but also serves as a sprue during pouring. Reference numeral 14 denotes a pressurizing lid, which has a box-like shape with a downward opening.
When placed on the upper surface of 1, it covers the opening of the feeder section 13 and forms a pressurizing chamber 15 above the opening. A packing 14a is attached to the lower edge of the pressurizing lid 14, that is, the portion that contacts the upper surface of the mold 11, so as to maintain airtightness within the pressurizing chamber 15. Further, an air supply hole 16 and an exhaust hole 17 are provided in the upper part of the pressurizing lid 14, respectively.
The air supply hole 16 is connected via a pipe 18 to a compressor 19 serving as an air supply means. On the other hand, the exhaust hole 17
is connected to a vacuum pump 21 via a pipe 2o, and a vacuum tank 22 having a relatively large volume is interposed in the middle thereof. Incidentally, each pipe 18.2° is provided with a valve 23.24 for opening and closing, respectively.

Reference numeral 25 denotes a hydraulic cylinder as a holding means, and the bottom of this hydraulic cylinder 25 is attached to the upper wall surface 27, while the tips of its ronds 28 are respectively connected to the upper part of the pressurizing lid 14. As a result, The pressurizing lid 14 is made movable in the vertical direction by the action of the hydraulic cylinder 25, and when pressurized air is introduced into the pressurizing chamber 15, the pressurizing lid 14 closes to the mold]
1 so as not to separate from the upper surface thereof.

Next, the procedure for performing pressure casting using the above-mentioned apparatus will be explained based on FIG. 3.

First, the mold 11 is clamped, molten metal is poured into the feeder section 13, the mold 11 is moved to a position below the pressure lid 14, and the hydraulic cylinder 25 is operated to close the pressure lid 14. It is lowered to cover the upper opening (boiler part) of the mold 11. Next, a predetermined period of time (for example, in the case of an aluminum alloy, a solidified shell is formed at the part where the /8 hot water contacts the casting surface).
After approximately 0 seconds have elapsed, the pulp 24 is released. At this time, the vacuum tank 22 maintained at a high degree of vacuum by the vacuum pump 21 and the inside of the pressurizing chamber 15 communicate with each other, and the air inside the pressurizing chamber 15 is sucked into the vacuum tank 22 and the pressurizing chamber 1
5 is depressurized, and at the same time, the vacuum pump 21 and the pressurizing chamber 15 communicate with each other, so that the pressurizing chamber 15 is further depressurized by the vacuum pump 21. The reason for reducing the pressure in the pressurizing chamber 15 prior to pressurizing in this way is to actively remove gas generated from the core and molten metal. Therefore, the inside of the pressurizing chamber 15 is 200 mb or less, preferably 100 mb or less.
Reduce the pressure to about mb. Then, in consideration of the next pressurization process, the depressurization is stopped before the solidification of the molten metal progresses much. This depressurization time is greatly affected by the type of molten metal, the dimensions of the product, etc., so it is impossible to define it unambiguously. However, for example, when manufacturing cylinder blocks for motorcycles using aluminum alloy, It takes about 30 seconds.

Note that in the above, depressurization is started after a solidified shell is formed on the surface of the casting, but if the depressurization timing is too early, leakage may occur from the mating surfaces of the mold 11 into the molten metal. This is to prevent this phenomenon. Next, the valve 24 is closed, and the other valve 23 is opened to guide pressurized air from the compressor 19 into the pressurizing chamber 15, thereby raising the pressure inside the pressurizing chamber 15. The reason for increasing the pressure in the pressurizing chamber 15 in this way is to prevent casting defects such as blowholes and porosity that occur during the solidification process of the molten metal. The pressure required at this time is, for example, 1500 to 3000 mb (in the case of aluminum alloy).
The gauge pressure is approximately 500 to 2000 mb). When 78 m of solidification is completed, the inside of the pressurizing chamber 15 is returned to atmospheric pressure, the pressurizing lid 14 is raised, the mold 11 is moved, the mold 11 is divided, and the product casting is taken out. Completed casting work.

In the pressure casting apparatus described above, there is no need to perform operations such as loading the pressure vessel into the pressure vessel and attaching and removing the vessel lid, unlike the conventional apparatus, and the mold is moved to a position below the pressure lid 14. Since pressure casting can be performed with a simple operation, it does not require much manpower, and therefore work efficiency can be improved. Furthermore, since it is only necessary to configure a small pressurizing chamber, the device can be manufactured at low cost. Moreover, if an exhaust means is provided to reduce the pressure inside the pressurizing chamber 15 as described above and the molten metal is degassed before pressurizing, it is possible to manufacture castings with even more stable quality. It becomes possible.

Although one embodiment of the pressure casting apparatus of the present invention has been described above, the pressure casting apparatus of the present invention is not limited to the above embodiment, and can be implemented with various modifications. For example, in the above example, an exhaust means is used to reduce the pressure inside the pressurized chamber, but since there is no need to use a core,
If gas is not generated much, it is possible to omit this exhaust means. Additionally, in the above, a hydraulic cylinder is used as the holding means for holding the pressurizing lid against the mold, but the point is that any device that can hold the pressurizing lid during pressurization is sufficient. Therefore, various means such as air cylinders, other structures using levers, etc. can be employed. Further, the air supply means is the same as described above, and any other arbitrary means may be employed.

The pressure casting apparatus of this invention is configured as described above, and therefore, according to the pressure casting apparatus of this invention,
Pressure casting can be performed simply by placing a pressurization lid on the mold, holding it with a holding means, and introducing pressurized air into the pressurization chamber. Since various operations such as attaching and removing the container lid are not necessary, it becomes possible to carry out casting operations with extremely high efficiency. Further, unlike conventional devices, a large pressure vessel is not required, and only a small pressurizing chamber is required, so the device is compact and can be manufactured at low cost.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of a conventional pressure casting device, Figure 2 is an explanatory diagram showing an example of a conventional pressure casting device.
The figure is an explanatory diagram of one embodiment of the pressure casting apparatus of the present invention, and the third
The figure is a graph schematically showing the pressure transition in the pressurizing chamber when casting is performed using the above-mentioned apparatus. 11... Mold, 14... Pressurizing lid, 15... Pressurizing chamber, 19... Compressor, 25... Hydraulic cylinder. Patent applicant: Kawasaki Heavy Industries, Ltd.

Claims (1)

[Claims] 1. A mold having an upwardly opening opening, a pressurizing lid for covering this opening and forming a pressurizing chamber above it, and an air supply means for supplying pressurized air into the pressurizing chamber. and,
A pressure casting apparatus comprising: a holding means for holding the pressure lid against the mold.