JPH07155899A - Device for molding gas hardening mold - Google Patents

Abstract

PURPOSE:To eliminate the uneven hardening at the time of blowing hardening gas by eliminating the uneven air filling at the time of blow-filling the air. CONSTITUTION:Vent holes 12a, 12b for exhausting the blowing air or the hardening gas from a metallic mold 10 are formed in a low mold 12 and the vent hole 12b near a blowing hole 11a is communicated with a through-hole 14a vertically penetrating the metallic mold 10. A sprue 15a as an opening/closing means and a return spring 16 for energizing the sprue 15a to the opening direction (upper direction in the figure) in the normal condition are interposed in the through-hole 14a. Further, a through-hole (14b) is arranged in an upper mold 11, too at the position faced to the through-hole 14a in the lower mold 12, and the sprue 15c and the return spring 16 are interposed in the through-hole. The lower end surface of the sprue 15a and the upper end surface of the sprue 15c are abutted in the condition of connecting the upper mold 11 with the lower mold 12, and the upper end part of the sprue 15c is energiged to the position projected at a prescribed size from the upper surface of the upper mold 11 in the normal condition with the return spring 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for a mold using gas-curable molding sand, and more particularly to a technique for eliminating defective filling during blow filling and eliminating defective curing during blowing of a curing gas.

[0002]

2. Description of the Related Art Conventionally, as a molding apparatus for a gas curing mold, there is, for example, one shown in FIGS. That is, this one uses the mold 10 in which the upper mold 11 and the lower mold 12 are free to open and combine as shown in FIGS. 5 and 6, and as shown in FIG. The blow head 17 in which the kneading sand 13 in which the sand and the binder are kneaded is injected in a state where the blow opening 17a and the blow opening 17a are provided so that the surface provided with the blow opening 17a contacts the upper surface of the upper mold 11, Blow air is blown from 17b to blow the kneading sand 13 into the blow port 17
The mold 10 is configured to be blow-filled from a.

The air in the mold 10 at the time of blow filling is
As the hollow portion inside the mold 10 is filled with the kneading sand 13, it is discharged to the outside of the mold 10 through the plurality of vent holes 12a and 12a.

[0004]

By the way, a phenolic resin or the like used in such a gas-curing mold is used as a binder (for binding sand to each other to give a caking property to facilitate molding of the mold). Since the binder is a liquid at room temperature, the state of the kneading sand 13 before hardening of the gas-hardening foundry sand is wet, and the kneading sand is more fluid than the near-dry kneading sand used in conventional shell molds. It is not very popular. Therefore, in a mold having a complicated shape, when the kneading sand 13 is blow-filled in the mold 10, as shown in FIG. 8, a filling failure part A of the mold is apt to occur, which causes a waste of the casting. However, since the filling density is low, there is a problem in that the molten metal is likely to be soaked into the mold, seizure, etc., and a good casting cannot be obtained.

Therefore, in order to solve such a problem, for example, as shown in FIG. 9, the existing vent holes 12a and 12a are installed.
Separately from 2a, vent holes 12b and 12b are newly formed at the corners of the mold where the filling failure of the kneading sand 13 is likely to occur, to improve the air bleeding in the mold 10 when the kneading sand 13 is blow-filled. It has been proposed to prevent the filling failure of the kneading sand 13.

However, this method by adding a vent hole can effectively prevent defective filling during blow filling processing of the kneading sand 13, as shown in FIG.
As shown in, in the step of introducing the curing gas into the kneading sand 13 in the mold 10 to cure the kneading sand 13, the discharge amount of the curing gas from the vent holes 12b, 12b near the blow port increases, Bent hole 12 far from the blow port
In the portions a and 12a, there is a problem that the curing gas is hard to spread and a defective curing portion B is generated.

Therefore, as a means for preventing such defective filling of the kneading sand and poor curing of the mold, the method is disclosed in Japanese Utility Model Laid-Open No. 4-434.
A gassing vent hole as disclosed in Japanese Patent No. 41 has been proposed. This one is equipped with a valve body that opens against the elastic force when the pressure in the mold becomes high, and functions as a vent hole that opens the valve body and discharges air under high pressure during blow filling of kneading sand, Under low pressure when the curing gas is blown, the valve body is closed by elastic force to prevent the curing gas from escaping too much.

[0008] However, in this device, since the valve body using the pressure in the mold as a drive source is used, as shown in FIG. 11, the vent hole exhaust pressure (exhaust flow rate) at the time of kneading sand blow filling is used There is a problem that a time lag is generated and a pressure loss for opening and closing the valve is generated between the air blow blowing port and the vent hole exhaust port. Further, this product has a problem in terms of reliability because the binder adheres to the valve body and the valve body is apt to malfunction.

The present invention has been made in view of the above-mentioned conventional problems, and provides a molding apparatus for a gas-curing mold that eliminates defective filling during blow filling and eliminates defective curing during blowing of a curing gas. The purpose is to do.

[0010]

In order to achieve the above object, the present invention blow-fills the kneading sand injected into the blow head with the blow air supplied from the blow air supply means into the mold through the blow port. Along with the curing gas supplied from the curing gas supply means, by introducing to the kneading sand blow-filled in the mold, the molding device of the gas curing mold for curing the kneading sand to mold the mold, the blow air Alternatively, a plurality of exhaust passages for discharging the curing gas from a plurality of locations in the mold, and an opening / closing means that is interposed in the exhaust passages closer to the corners of the mold among the plurality of exhaust passages and can open and close the passages. And an opening / closing switching unit that opens the opening / closing unit in the blow filling process and closes the opening / closing unit in the gas curing process.

[0011]

According to this structure, when the kneading sand is blow-filled, the opening / closing means is opened to open the exhaust passage nearer to the corner of the mold to improve the air bleeding in the mold and to improve the mixing of the kneading sand. Poor filling can be prevented. Further, during the gas curing process, the opening / closing means is closed to close the exhaust passage nearer to the corner of the mold to prevent the curing gas from escaping too much and prevent the occurrence of curing failure.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIGS. 1 to 4, a gas curing mold making apparatus according to an embodiment of the present invention will be described. That is, as shown in FIG. 1 and FIG. 2, the upper mold 11 and the lower mold 12 form a mold 10 that can be freely opened and combined, and the kneading sand 13 is formed inside the mold 10 on the upper surface of the upper mold 11. Blow mouth for blow filling 1
1a is formed.

Further, the lower mold 12 is formed with a plurality of vent holes 12a, 12b, ... As exhaust passages for discharging blow air or curing gas from a plurality of places in the mold, and is close to the corners of the mold. The other vent hole 12b communicates with a through hole 14a that penetrates the mold 10 in the vertical direction.
The through hole 14a has a sprue 15 as an opening / closing means.
A return spring 16 that normally biases a and the sprue 15a in the opening direction (upward direction in the drawing) is provided. That is, the valve 15b of the sprue 15a moves vertically in the through hole 14a, so that the outlet 12 of the exhaust passage is
It is designed to open and close c.

The upper die 11 also has a through hole 1 in the lower die 12.
4a, a through hole 14b is provided at a position facing the 4a, and the sprue 15c and the return spring 1 are provided in the through hole 14b.
6 is interposed, the lower end surface of the sprue 15a and the upper end surface of the sprue 15c abut with the upper mold 11 and the lower mold 12 coupled, and the upper end of the sprue 15c is always in contact with the upper mold 1
The return spring 16 urges the position of 1 above a predetermined amount.

Then, in order to blow-fill the kneading sand 13 into the die 10, as shown in FIG.
Kneading sand 13 in which sand and a binder are kneaded in a state of being combined with
The blow head 17 into which the air is injected is disposed so that the surface provided with the blow port 17a contacts the upper surface of the upper mold 11, and blow air is blown from the air port 17b to mix the kneading sand 1
3 is blow-filled into the mold 10 through the blow port 17a.
In this case, the upper end of the sprue 15c is
Since it is located at a position away from 7, it is located at a position projecting from the upper surface of the upper mold 11 by a predetermined amount.

Therefore, the sprue 15a is in the open state, and the air in the mold 10 at the time of blow filling is completely filled as the cavity in the mold 10 is filled with the kneading sand 13 as shown by the arrow in the figure. Vent holes 12a, 12b
It is designed to be discharged to the outside of the mold 10 via. Since the sprue 15a is in the open state and the valve 15b is located away from the inlet portion of the vent hole 12b, there is no possibility that a malfunction will occur due to the sticking agent adhering to the valve 15b.

Next, when the blow-filling of the kneading sand 13 into the mold 10 is completed, the blow head 17 is removed from the mold 10 and the blow-filling kneading sand 13 is gas-cured as shown in FIG. As described above, the curing gas blowing chamber 18 is attached to the upper surface of the upper mold 11, and the exhaust chamber 19 is attached to the lower surface of the lower mold 12. A hardening gas supply passage 21 communicating with a hardening gas generator 20 is connected to the hardening gas blowing chamber 18, and the hardening gas is introduced into the kneading sand 13 in the mold 10 to harden the kneading sand 13. ing.

In this case, the curing gas blowing chamber 1
A push-in pin 18a is provided inside 8 at a position opposed to the upper end of the sprue 15c, and the upper end of the sprue 15c is pushed down by the push-in pin 18a against the urging force of the return spring 16. The valve 15b of the sprue 15a interlocking therewith moves downward to close the outlet 12c of the exhaust passage. Therefore, the hardening gas is prevented from escaping too much, and the hardening gas is spread to every corner of the kneading sand 13, so that the hardening failure of the kneading sand 13 is prevented.

When the hardening gas is introduced, the exhaust blower 22 communicating with the exhaust chamber 19 is driven so that the exhaust blower 22 sucks the kneading sand 13 in the mold 10.
A large amount of curing gas is introduced to suppress the curing failure, and the suction negative pressure tightens the kneading sand 19 to improve the packing density of the mold 15, so that the molten metal penetrates into the mold 15 during casting. By preventing the occurrence of seizure, etc., a good casting is obtained.

When the molding of the mold is completed, the upper mold 11
The lower mold 12 is separated from the lower mold 12, and the mold is taken out from the mold 10. At this time, the sprues 15a and 15c are moved upward by the urging force of the return spring 16 to restore the exhaust passage to the opening direction. After the completion of molding of the mold, a return pin is attached to a push plate (not shown) that pushes the mold out of the mold 10 to forcibly push up the sprue 15a to prevent malfunction of the return spring 16. May be.

Thus, during blow-filling of kneading sand,
By opening the exhaust passage of the vent hole closer to the corner of the mold and discharging the air through all the vent holes 12a, 12b, ... Improves the air bleeding in the mold and prevents the filling failure of the kneading sand. In addition, at the time of the gas curing process, it is possible to prevent the curing failure from occurring by closing the exhaust passage of the vent hole closer to the corner of the mold to prevent the curing gas from escaping too much.

[0022]

As described above, according to the present invention,
A plurality of exhaust passages for discharging blow air or curing gas from a plurality of locations in the mold, and an opening / closing opening provided in the exhaust passage closer to the corner of the mold among the plurality of exhaust passages so that the passages can be opened and closed. Means, and in the blow filling process step,
Since the opening / closing means is opened, and the opening / closing means is closed in the gas curing process, the opening / closing means is opened and the exhaust passage nearer to the corner of the mold is also opened during blow filling of the kneading sand. Opening prevents defective filling of kneading sand, and during gas curing treatment,
By closing the opening / closing means and closing the exhaust passage nearer to the corner of the mold, the escape of the curing gas is prevented and the curing failure does not occur.

[Brief description of drawings]

FIG. 1 is a view showing a state in which an upper mold and a lower mold of a mold used in a gas curing mold making apparatus according to the present invention are separated.

FIG. 2 is a view showing a state in which an upper die and a lower die of the mold are also joined together.

FIG. 3 is a diagram for explaining blow-filling processing of kneading sand in a gas-curing mold making apparatus according to the present invention.

FIG. 4 is a diagram illustrating a gas curing process in a gas curing mold making apparatus according to the present invention.

FIG. 5 is a view showing a state in which a mold in a conventional example is separated into an upper mold and a lower mold.

FIG. 6 is a view showing a state in which an upper die and a lower die of a mold in a conventional example are joined.

FIG. 7 is a diagram illustrating a blow-filling process of kneading sand in a conventional example.

FIG. 8 is a diagram illustrating a blow-filling process of kneading sand in a conventional example.

FIG. 9 is a view for explaining blow-filling processing of kneading sand in a conventional example.

FIG. 10 is a diagram illustrating a gas curing process in a conventional example.

FIG. 11 is a diagram showing a relationship between time and gas pressure in a conventional example.

[Explanation of symbols]

 10 mold 11 upper mold 11a blow port 12 lower mold 12a, b vent hole 12c outlet 13 kneading sand 14a, b through hole 15a, c sprue 15b valve 16 return spring 17 blow head 17a blow port 17b air port 18 curing gas blowing chamber 18a Push-in pin 19 Exhaust chamber 20 Curing gas generator 21 Curing gas supply passage 22 Exhaust blower

Claims (1)

[Claims] 1. A kneading sand injected into a blow head by blow air supplied from a blow air supply means is blow-filled into a mold through a blow port, and a hardening gas supplied from a hardening gas supply means is supplied to the metal mold. In a molding apparatus for a gas-curing mold that cures the kneading sand and molds the mold by introducing the blow-filled kneading sand into the mold, the blow air or the curing gas is discharged from a plurality of locations in the mold. An exhaust passage, an opening / closing means that is interposed in the exhaust passage closer to the mold corner among the plurality of exhaust passages, and that can open and close the passage; and in the blow filling process step, opening and closing the opening and closing means, In the gas curing step, an opening / closing switching unit for closing the opening / closing unit is included, and a molding device for a gas curing mold.