JPH0522366Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a mold used in a casting method that utilizes differential pressure (hereinafter referred to as differential pressure casting method), and more specifically relates to a mold that is equipped with a gas venting structure. Regarding types.

(Prior Art) Conventionally, there is a method known as differential pressure casting, in which an airtight case is provided outside a mold to improve the circulation of molten metal, and the pressure inside the airtight case is reduced during casting. This differential pressure casting method is generally carried out using an apparatus as shown in FIG. In this device, a mold 31 is provided in an airtight chamber 32 that can be depressurized, and a holding furnace 3 that can be pressurized is located below the mold 31.
The molten metal 34 in the mold 3 is poured through a stalk 36 communicating with the lower part of the lower mold 35 into a gear space 38 formed by the upper mold 37 and the lower mold 35.

A vent 40 with a depth of about 2 mm is carved in the cutout surface 39b of the lower mold 35 for discharging the gas inside the cavity 38 to the outside of the mold 31, that is, into the airtight chamber 32. This vent 40 may be carved in the parting surface 39a of the upper mold 37 in some cases. In the figure, 41 is a boss forming part provided on the upper mold 37, 42 is a floor of the airtight chamber 32, 43 is a seal rubber that keeps the airtight chamber 32 sealed, 44 is a furnace lid of the holding furnace 33, 45,
Reference numerals 46 denote hoses connected to vacuum pumps (not shown) that change the pressures of the airtight chamber 32 and the holding furnace 33, respectively.

In addition, the differential pressure casting method using such a device is a suction casting method in which the inside of the airtight chamber 32 is depressurized and the inside of the holding furnace 33 is opened to the atmosphere, and the inside of the airtight chamber 32 is opened to the atmosphere and the inside of the holding furnace 33 is pressurized. It can be roughly divided into three methods: a pressure casting method, and a method in which the inside of the airtight chamber 32 is pressurized and the inside of the holding furnace 33 is pressurized with a higher pressure.

Incidentally, in the suction casting method, the furnace cover 44 and the hose 46 of the holding furnace 33 may not be provided, and in the pressure casting method, the airtight chamber 32 and the hose 45 of the airtight chamber 32 may not be provided.

By the way, in the mold 31 in which the vent 40 is provided on the mold parting surface, the boss molding part 41 provided on the upper mold 37 is connected to the vent 4 provided on the mold parting surface 39.
Since it is located at a higher position than 0 and has a recess formed upward, the poured molten metal flows through the vent 4.
When the temperature reaches above 0, the gas is stored in the boss molded product 41 as shown in FIG. For this reason, the molten metal 34 does not flow until it reaches the boss forming portion 41, resulting in a problem that casting defects occur due to poor molten metal flow.

Therefore, in view of this point, the applicant
The gas stored in the boss molded product 41 in the mold 31
Mold 3 equipped with a gas venting structure to discharge the gas to the outside.
1 and has already filed an application for utility model registration (Utility Model Application No. 147695, 1983). As shown in FIG. 7, the surface of the mold inner surface extending from the boss forming part 41 to the upper mold parting surface 39a is made of ceramics such as zirconia, ittria, etc. or Ni-Co-Al with a thickness of about 100 μm to 500 μm. A composite metal sprayed layer 51 is provided.

In this way, the sprayed layer 51 has a structure in which the sprayed particles 52 are fused to the laminated layer while maintaining their particle shape, so that voids 53 are present in the laminated portion, and the inner surface of the mold 31 A degassing passage is formed in the thermal spray layer 51 provided on the surface extending from the boss molded product 41 to the mold parting surface 39. As a result, the gas stored in the boss forming portion 41 is discharged out of the mold 31 through this passage. Therefore, as shown in FIG. 9, the boss forming portion 41 is filled with the molten metal 34, and there is no problem in the flow of the molten metal.

The present invention further improves this structure so that the grooves and the sprayed layer form a reliable degassing passage, allowing gas to be sucked in and discharged smoothly.

(Means for solving the problem) In order to solve the above problem, the mold 3 of the present invention has the following features:
From the boss molding part 13 on the inner surface of the mold 3 to the mold parting surface 14
A structure 15 is provided on the surface extending to the outermost end of the groove 15, and a sprayed layer 16 is provided within the groove 15.

This structure 15 may have any shape such as a square groove, a U groove, or a V groove of a required width.

The sprayed layer 16 may be made of a ceramic material such as zirconia or itria, or a metal material such as a Ni--Cr--Mo composite. And this sprayed layer 16
The entire groove portion 15 may be filled with the groove portion 15, or the entrance side of the groove portion 15 may be covered with the groove bottom 19 to form a cavity 20.

This groove 15 is required to have a required width from at least the top of the boss forming part 13 to the outermost edge of the mold parting surface 14, or to the vent if a vent is formed. .

(Function) The sprayed layer 16 in the groove 15 of the mold 3 configured as described above is formed by stacking the sprayed particles 17 while almost maintaining their particle shape, so that there are holes 18 in the sprayed layer 16. As a result, a gas vent passage is formed in the groove 15 provided on the inner surface of the mold 3 extending from the boss molding part 13 to the outermost end of the mold parting surface 14. As a result, the gas stored in the boss forming portion 13 is discharged to the outside of the mold 3 through this passage. Furthermore, when the entrance side of the groove 15 is covered with a sprayed layer 16 and the groove bottom 19 is made into a cavity 20, the gas stored in the boss forming part is mainly discharged to the outside of the mold 3 through the groove bottom 19 of the cavity 20. Ru. Therefore, poor water flow will not occur in the boss molded portion.

(Example) Next, an example of the present invention will be described based on the drawings. FIG. 1 is a sectional view of a casting apparatus using a mold having a gas venting structure according to the present invention.

In this apparatus, a mold 3 consisting of a combination of an upper mold 1 and a lower mold 2 is installed in an airtight chamber 4 and on a floor 5. The sprue 6 of the mold 3 is connected to a stalk 7 provided through the floor 5 of the airtight chamber 4. Further, the lower end of the stalk 7 is inserted into a molten metal 9 of a light alloy inside a holding furnace 8 below the mold 3. The airtight chamber 4 and the upper mold 1 are connected to a cylinder rod (not shown) provided above, and the airtight chamber 4 and the upper mold 1 can be separated and combined with the floor 5 and the lower mold 2 by raising and lowering the rod. ing.

10 is a rubber seal used to maintain the pressure inside the airtight chamber 4, and 11 is a hose connected to a vacuum pump (not shown) that pressurizes and depressurizes the inside of the airtight chamber 4.

On the other hand, a boss forming part 13 for forming a round boss is provided in the upper part of the cavity 12 formed by the upper mold 1 and the lower mold 2, that is, on the upper mold 1 side. In order to improve the flow of hot water inside the boss forming part 13, the mold parting surface 1 is
Square groove 1 of the required width on the surface of the parting surface extending to the outermost edge of 4.
5 (this may be a U-groove or a V-groove) is formed, and a metal sprayed layer 16 of Ni--Cr--Mo is embedded in this square groove 15 (see FIG. 2). As shown in FIG. 3, this sprayed layer 16 has a structure in which sprayed particles 17 are fused to the laminated layers within the square grooves 15, so that voids 18 are present in the laminated portions. Therefore, a degassing passage is formed from the boss forming part 13 to the outermost end of the mold parting surface 14.

Low-pressure casting is performed using the mold 3 configured as described above. First, the inside of the airtight chamber 4 is depressurized by a vacuum pump (not shown), the inside of the cavity 12 is depressurized through the sprayed layer 16 in the square groove 15, and the molten metal 9 in the holding furnace 8 flows into the cavity 12 through the stalk 7. . At this time, the gas in the cavity 12 is discharged to the outside of the mold 3 through the holes 18 of the sprayed layer 16 in the square groove 15, that is, the gas vent passage, and no gas is stored in the boss molding portion 13. Therefore, the molten metal 9 reaches every corner of the boss forming part 14, and no malfunction occurs. The molten metal 9 does not penetrate into the sprayed layer 16 in the square groove 15.

In this embodiment, the sprayed layer 16 is embedded in the entire square groove 15 (see FIG. 2), but the invention is not limited thereto. It may be set to 20. This has the effect of allowing the gas to pass more actively.

Further, although this embodiment has been described using a suction casting method, a pressure casting method or a casting method in which the airtight chamber 4 and the holding furnace 8 are pressurized may also be used. In either casting method, gas is discharged to the outside of the mold 3 to completely fill the mold with molten metal.

(Effects of the invention) As described above in detail, the present invention provides a groove on the inner surface of the mold extending from the boss forming part to the mold parting surface, and also forms a sprayed layer within this groove. Because of this, the gas stored in the boss molding section is discharged to the outside of the mold through the sprayed layer in the groove. Therefore, casting defects due to poor hot water circulation are eliminated and the yield is greatly improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a suction casting device showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 is a main part of the mold of one embodiment, that is, the interior of the groove. Figure 4 is an enlarged cross-sectional view showing the sprayed layer of Figure 1.
5 is a sectional view showing an example of a device used in a conventional casting method using differential pressure; FIG. Figure 7 is a cross-sectional view of a device using a mold with a sprayed layer formed on the boss molding part and the parting surface.
FIG. 8 is an enlarged sectional view showing the sprayed layer of the mold, and FIG. 9 is a sectional view showing the cavity of the mold provided with the sprayed layer filled with molten metal. 3...Mold, 13...Boss forming portion, 14...Parting surface, 15...Groove (square groove), 16...Sprayed layer.

Claims (1)

[Scope of utility model registration request] In a mold used in a casting method using differential pressure, a groove is provided on the surface from the boss forming part on the inner surface of the mold to the outermost end of the mold parting surface, and a thermal spray layer is provided within the groove. A mold with a characteristic gas venting structure.