KR20010046274A - Low pressure moulding apparatus having improved dies - Google Patents

Abstract

PURPOSE: A low pressure casting apparatus equipped with improved dies is provided in which combustion gas does not remain in cavities without replacement of any members, thereby shortening the processes and reducing expenses for the low pressure casting. CONSTITUTION: The apparatus comprises a lower die on the lower part of which a sprue into which molten metal is flown is formed, and on the upper surface of which a first parting surface; an upper die (132) on the lower surface of which a second parting surface is formed, and in the inside of which a cavity (136) is formed together with the lower die when the first parting surface (133) and the second parting surface (133) are contacted each other; a molten metal infusion means for flowing the molten metal into the cavity (136) through the sprue by the pressure of gas; an insert inserted into the cavity for forming the molten metal flown in into a desired shape; and a serration connecting from the cavity to the outer space of the upper and lower dies formed on at least of the first parting surface and the second parting surface.

Description

Low pressure molding apparatus having improved dies

TECHNICAL FIELD The present invention relates to a low pressure casting apparatus, and more particularly, to a low pressure casting apparatus which does not leave combustion gas in a cavity without replacing any member, and thus can shorten the maneuver of low pressure casting and reduce the low pressure casting cost. .

The cylinders and engine blocks of automobiles are often made by casting, especially low pressure casting. Low pressure casting is a product of the shape required by injecting aluminum molten metal into the cavity of a metal mold by low pressure air or gas pressure. The processing method to cast.

Referring to the schematic side view of the general low pressure casting apparatus shown in FIG. 1, a conventional low pressure casting apparatus includes a stoke tube 13 connected to an upper mold 32, a lower mold 31, and a lower mold 31. And a heat retaining furnace 11 in which the lower end of the stoke tube 13 is accommodated. The gas duct 12 is formed in the side wall of the heat retention furnace 11, and the gas duct 12 communicates with the upper space 14 of the molten metal 20 inside the heat retention furnace 11.

The lower surface of the lower die 31 is formed with a spout 15, and a stalk tube 13 is connected to the spout 15. Reference numeral 33 denotes a mating surface where the upper mold 32 and the lower mold 31 are in contact with each other, and the core 35 is formed in the cavity 36 formed by the upper mold 32 and the lower mold 31. It is built. The core 35 is generally made of a material coated with resin in sand to generate gas due to combustion of the resin when it comes into contact with the hot molten metal 20.

The upper mold 32 is embedded with a plurality of vent members 34 in the vertical direction, which is shown in more detail in FIG. The vent member 34 is a cylindrical member in which a number of through holes 41 extending in the longitudinal direction are formed.

Referring to the low pressure casting process by the conventional low pressure casting device having the above structure, first, the high temperature molten metal 20 is contained in the heating furnace 11, and then the air of low pressure through the gas duct 12 Or inert gas. When the pressure of the injected gas reaches a predetermined value, the molten metal 20 is injected into the cavity 36 through the stoke tube 13 and the spout 15. The molten metal 20 injected into the cavity 36 flows into the space between the core 35 and the mold 31, and thus the internal shape of the product cast by the core 35 is molded.

At this time, the core 35 is in contact with the hot melt 20 to generate a gas due to the combustion of the resin component, the combustion gas is passed through the through-holes 41 of the vent member 34, the upper die ( 32) to be released to the outside.

However, the diameter of the through-holes 41 for inducing gas discharge is set to 0.4 mm or less so as to prevent the outflow of the molten metal 20, so that the through-holes are penetrated due to the combustion material or other foreign substances of the resin component. It is common that the balls 41 are blocked. Once the through-holes 41 are blocked, the combustion gas remains inside the cavity 36, thereby providing resistance to the upward force of the molten metal 20 by the low pressure gas, which adversely affects the filling properties of the molten metal. .

In order to prevent this, it is necessary to replace the vent member 34 from time to time, the conventional low-pressure casting apparatus has the disadvantage that the cost increases due to the replacement of the vent member 34 and the work is complicated and the number of labor.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems as described above, and therefore the object of the present invention is not to leave combustion gas in the cavity without replacing any member, thus shortening man-hours of low pressure casting and low pressure casting cost. It is to provide a low pressure casting apparatus that can reduce the.

1 is a schematic side view of a general low pressure casting device,

2 is a schematic perspective view of an inverted state of a phase mold used in a conventional low pressure casting apparatus,

3 is an enlarged perspective view of the vent provided in the image mold of FIG.

4 is a schematic perspective view of an inverted state of a phase mold used in a low pressure casting apparatus according to an embodiment of the present invention, and

FIG. 5 is an enlarged perspective view of one groove of a serration formed in the upper mold of FIG. 4.

* Description of the symbols for the main parts of the drawings *

11: insulation furnace 12: gas duct

13: stoke tube 14: internal space

15: molten metal 20: molten metal

31: lower mold 32, 132: upper mold

33, 133: mating surface 34: vent

35: middle 36: cavity

41: through hole 133: serration groove

141: home

In order to achieve the above object, the low-pressure casting apparatus provided by the present invention, the molten metal inlet is formed in the lower portion, the lower mold having a first mating surface on the upper surface; An upper mold having a second mating surface on a bottom surface and forming a cavity therein with the lower mold when the first mold surface and the second mold surface are in contact with each other; Molten metal injection means for allowing the molten metal to flow into the cavity through the molten metal by the pressure of a gas; And a core for molding the molten metal introduced into the cavity into a desired shape, wherein at least one of the first mold face and the second mold face has an outer space of the upper and lower molds from the cavity; The serration which communicates with is formed.

Preferably, the molten metal injection means includes a stoke tube connected to the lower side of the molten metal, a lower end of the stoke tube, and an insulation furnace in which the molten metal is embedded, and a lower end of the stoke tube in the insulation furnace is provided. It is immersed in the molten metal, a gas duct is formed on the side wall of the heat insulating furnace communicating with the upper space of the molten metal, when the low pressure gas is injected through the gas duct by the pressure of the gas is the stoke tube and It is injected into the cavity through the spout.

In addition, the serration includes a plurality of grooves extending from the inner end to the outer end of the first mating surface or the second mating surface, each of the grooves having a V-shaped cross section. More preferably, the gap between each of the grooves is small enough to prevent leakage of the molten metal. Sidewalls of the upper mold may slide and move along a slide surface, and serrations may be formed on the slide surface.

Hereinafter, a low pressure casting apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. 4 is a schematic perspective view showing an inverted state of a phase mold used in a low pressure casting apparatus according to an embodiment of the present invention, and FIG. 1 schematically shows a general low pressure casting apparatus in which the phase mold of FIG. 4 may be adopted. Phosphorus side view is shown.

1 and 4, a low pressure casting apparatus according to an embodiment of the present invention includes an upper die 132 and a lower die 31. The upper mold 132 has a mating surface 133 on the bottom surface, and a serration 134 is formed on the mating surface 133. Although not separately shown, the lower mold 31 also has a mating surface 33 on the upper surface, and a molten iron 15 into which the molten metal 20 flows is formed at the lower portion. When the mating surface of the upper mold 132 and the mating surface of the lower mold 31 contact each other, a cavity 36 is formed inside the upper mold 132 and the lower mold 31.

In the cavity 36, an insert 35 is formed to mold the molten metal 20 flowing into the required shape. The core 35 is generally made of a material coated with resin in sand, and generates gas due to combustion of the resin in contact with hot molten metal.

On the other hand, the stalk tube (13) is connected to the spout (15), the stalk tube (13) extends downward and is embedded in a heating furnace (11). The molten metal 20 is accommodated in the thermal furnace 11, and the lower end of the stoke tube 13 is locked in the molten metal 20. The gas duct 12 which communicates with the upper space 14 of the molten metal 20 is formed in the side wall of the heat retention furnace 11.

On the other hand, referring again to Figure 4, the serration 134 formed on the mating surface 133, from the inner end of the cavity 136, that is, the mating surface 133, the outside of the upper and lower molds (132, 31) It includes a plurality of grooves 141 extending to a space, that is, to the outer end of the mating surface 133. Each groove 141 has a V-shaped cross section as shown in FIG. Depending on the embodiment, not necessarily a groove having a V-shaped cross section, but a groove having a semicircular or other shape may be used. Each gap or gap of the groove 141 has a sufficiently small dimension, such as 0.4 mm, such that the melt 20 does not leak.

In addition, although not shown, a sliding surface is formed at a predetermined position in the middle of the side wall of the upper mold 132, and the side wall may be configured to slide and move along the sliding surface, wherein the sliding surface Serrations may also be formed.

Hereinafter, the operation of the low-pressure casting apparatus according to an embodiment of the present invention having the above configuration will be described.

At the time of low pressure casting, the high temperature molten metal 20 is soaked in the heat retention furnace 11, and low pressure gas is inject | poured through the gas duct 12. Then, as shown in FIG. At this time, an inert gas or air is usually used as the injection gas. When the pressure of the injected gas reaches a predetermined value, the molten metal 20 is injected into the cavity 36 through the stoke tube 13 and the spout 15.

The molten metal 20 injected into the cavity 36 flows into the space between the core 35 and the molds 132 and 31, and thus the internal shape of the product is molded by the core 35. At this time, since the core 35 is made of a material coated with resin in the sand as described above, the core 35 comes into contact with the hot molten metal 20 to generate gas due to the combustion of the resin, and this combustion gas is used in the upper mold ( It leaks through the serration 134 formed between the 132 and the lower mold 31. Therefore, no combustion gas remains in the cavity 36, and as a result, the molten metal can be well filled to the required shape without applying a resistance to the molten metal 20 injected into the cavity 36.

In addition, as described above, each gap or gap of the groove 141 has a dimension sufficiently small that the molten metal 20 does not leak, so that the molten metal 20 outside of the molds 132 and 31 is removed. There is no leakage, and even if the grooves 141 of the serration 134 are blocked by ash or other dirt of the resin, it is only necessary to clean the serration 134 without having to replace any member. By this, the low pressure casting device can be reused.

As described above, according to the present invention, there is provided a low pressure casting apparatus which does not leave combustion gas in the cavity without replacing any member, and thus can shorten the maneuver of the low pressure casting and reduce the low pressure casting cost.

In the above, the present invention has been described in accordance with one preferred embodiment of the present invention, but the present invention is not limited to the described embodiments, but variously within the scope of the technical scope defined by the spirit and claims of the present invention. Modifications and variations are apparent to those skilled in the art.

Claims (5)

A lower mold having a molten metal in which a molten metal is introduced therein, and having a first mold surface on an upper surface thereof; An upper mold having a second mating surface on a bottom surface and forming a cavity therein with the lower mold when the first mold surface and the second mold surface are in contact with each other; Molten metal injection means for allowing the molten metal to flow into the cavity through the molten metal by the pressure of a gas; And It includes a core for molding the molten metal is installed in the cavity into the required shape, At least one of the first mating surface and the second mating surface is a low-pressure casting apparatus, characterized in that the serration is formed to communicate the outer space of the upper and lower molds from the cavity. According to claim 1, wherein the molten metal injection means comprises a stoke tube connected to the lower side of the molten opening, the lower end of the stoke tube and the heat insulating furnace in which the molten metal is built, the lower end of the stoke tube inside the heat insulating furnace Is immersed in the molten metal, and a gas duct communicating with the upper space of the molten metal is formed on the sidewall of the heating path, and when the low pressure gas is injected through the gas duct, the molten metal is stalked by the gas. Low pressure casting device characterized in that it is injected into the cavity through the tube and the hot water spout. 3. The serration according to claim 1 or 2, wherein the serration includes a plurality of grooves extending from an inner end to an outer end of the first mold mating surface or the second mold mating surface, wherein each of the grooves is a V-shaped cross section. Low pressure casting apparatus characterized by having a. 4. The low pressure casting apparatus according to claim 3, wherein the gap of each of the grooves is small enough to prevent leakage of the molten metal. The low pressure casting apparatus of claim 3, wherein the sidewalls of the upper mold may slide along the slide surface, and serrations are formed on the slide surface.