JPH0534837Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to a vent hole for mold making in which a vent hole is provided through the upper wall of the upper end of the cylindrical body.

<<Prior Art>> This type of vent hole is used, for example, in a mold making apparatus shown in FIGS. 7 and 8. That is, molding sand 11 mixed with a binder is filled into the cavity 2a inside the mold 2 with compressed air 8, and the mold 10 is filled with molding sand 11 mixed with a binder.
When molding, an air vent hole 6 is provided in the wall of the upper mold 3 and lower mold 4 of the mold 2, and the air vent hole 6
By inserting the vent hole 12 into the mold, the filling pressure of the compressed air 8 compacts the molding sand 11 and brings it into close contact with the mold inner surface 7, and prevents the molding sand 11 from flowing out from the air vent hole 6.

After filling the molding sand 11, the molding sand hardening gas 9 is blown into the mold cavity 2a to react with the binder to harden the molding sand 11. Then, the upper mold 3 and the lower mold 4 are opened to open the mold 10. I'm trying to take it out.

As shown in FIG. 9, the conventional vent hole 12 used in this mold making apparatus 1 is constructed by providing a vent hole 16 in the upper wall 15 through the vent hole 17 in the cylinder body 13. The upper and lower parts of the vent hole 12 are always communicated with each other.

<<Problem to be solved by the invention>> However, since the conventional vent hole 12 has a ventilation hole 16 formed through the upper wall 15 to constantly communicate the upper and lower parts of the vent hole 12, the molding sand hardening gas 9 Even in the case of filling, the curing gas 9 passes through the air holes 16 of the vent hole 12 and flows out from the air vent holes 6 provided in the upper mold 3 and the lower mold 4.

As a result, not only is the hardening gas 9 wasted, but a hardening gas flow path from the injection port 5 to the air vent hole 6 is formed in the molding sand 11 in the mold cavity 2a, and the hardening gas 9 is Since it is difficult to spread the sand to other parts within the cavity 2a, there is a problem in that the molding sand 11 hardens poorly.

In addition, if the curing gas is toxic, the mold 2
The working environment deteriorates due to the hardening gas 9 flowing out from the hardening gas 9, and workers must wear gas masks and dustproof goggles to avoid the effects of the hardening gas 9.
There was a problem with poor workability.

The present invention allows the hardening gas 9 to be sufficiently distributed in the cavity 2a of the mold 2 without wasting it, hardens the molding sand 11 to every corner, and has a hard surface that is densely packed and has a stable surface. The purpose of the present invention is to provide a vent hole that allows molding with good quality.

<<Means for Solving the Problems>> In order to achieve the above object, the present invention has an upper wall with a ventilation hole formed through the upper end of the cylinder body, and the ventilation hole and the opening at the lower end of the cylinder body. In a vent hole that communicates with an air passage, an on-off valve is attached inside the cylinder body, and a valve body that enables the on-off valve to seal the vent hole or the air passage, and this valve body is attached to the upper wall with elastic pressure. The setting pressure of the valve closing spring is set lower than the foundry sand filling pressure and higher than the foundry sand hardening gas filling pressure.

<Operation> In this invention, the closing spring setting pressure of the on-off valve built into the vent hole is set lower than the molding sand filling pressure and higher than the molding sand curing gas filling pressure, so that compression is not performed when filling the molding sand. The filling pressure of the air closes the opening/closing valve against the valve closing spring, and the compressed air can escape through the ventilation passage from the ventilation hole provided in the upper wall of the vent hole.

In addition, when filling the curing gas, the closing spring closes the opening/closing valve against the filling pressure of the curing gas, sealing the vent hole or air passage, thereby sealing the air vent hole and curing. Gas outflow can be prevented.

<<Effects of the invention>> Since the present invention is constructed and operates as described above, it has the following effects.

B. The on-off valve is opened when filling with foundry sand, so
The compressed air at the time of filling can be discharged from the ventilation hole provided in the upper wall of the vent hole to the air vent hole through the ventilation path, and the filling density can be increased without leaving any air bubbles in the molding sand.

(b) Since the air vent hole is sealed when filling the curing gas, the curing gas does not leak out from the mold, making it possible to use the curing gas effectively. It is possible to spread the molding sand to every corner within the molding sand, thereby reliably preventing the occurrence of poor hardening of the molding sand.

C. The filling pressure allows the curing gas to spread throughout the mold cavity, so even when molding thick molds, the curing gas can be spread to the inside of the molding sand in a short time, resulting in uniform hardening and strength. It is possible to create molds with high performance.

D. Since the curing gas does not leak out from the mold, the working environment does not deteriorate, and furthermore, the work efficiency is good because the worker does not need to wear a gas mask or dust-proof glasses.

E. It has a simple structure in which the on-off valve is placed on the lower end side of the upper wall of the vent hole, and it is not only available at low cost, but also can be installed in the mold by simply attaching the vent hole to the air vent hole. Therefore, even if the air vent hole is provided in a complicated part of the mold, it can be attached extremely easily.

Moreover, when the valve body and the valve closing spring are integrally constructed, the number of parts can be reduced, and the vent hole can be easily assembled and provided at a lower cost.

F. If the valve body of the on-off valve is in contact with the lower surface of the upper wall, the vent hole will be sealed when the hardening gas is filled.
Since hardening gas does not enter the vent hole, even if fine molding sand powder enters the vent hole from the vent hole during filling with molding sand, it will not harden and block the ventilation path. Never.

"Example" Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show Example 1 of the present invention,
FIG. 1 is a partially cutaway perspective view of the vent hole, and FIG. 2 is a plan view of the on-off valve.

The cylindrical body 13 of the vent hole 12 has an annular upper wall fixing part 14 projecting from the inner surface of the upper end thereof, and a circular upper wall 15 is attached inside the upper wall fixing part 14.

The upper wall 15 is made of a thin stainless steel plate, and has ventilation holes 16 formed by punching out a large number of round holes.

In this embodiment, the upper wall 15 is made of a thin stainless steel plate with a large number of round holes punched out, but the upper wall 15 is not limited to this, and can be made of a thin metal plate with long hole slits, a wire mesh, etc. It may be composed of, or
It may also be a plastic molded product. Alternatively, the cylinder main body 13 and the upper wall 15 may be integrally formed and the upper wall 15 may be provided with a ventilation hole 16 therethrough.

An opening/closing valve 20 is disposed on the lower side of the upper wall 15 and is formed by integrally forming a valve closing spring 19 and a circular valve element 18. By bringing the valve element 18 into contact with the lower surface of the upper wall 15, the opening and closing valve 20 is installed. The pores 16 are configured to be sealable.

The on-off valve 20 is made of a circular thin plate made of stainless spring steel, and as shown in FIG. 2, a C-shaped slit groove is provided along the periphery of the disk, and an annular support part 25 on the outer periphery and a circular valve body inside. 18 are connected by a plate spring portion 19.

The valve body 18 of the on-off valve 20 is not limited to stainless steel and may be made of plastic, rubber, etc., but if stainless spring steel is used, it will not deteriorate due to the organic binder in the foundry sand 11 or the hardening gas 9.
In addition, there is no damage due to pressure during filling, there is no adhesion of fine sand powder, and there is no rust, so it can be used for a long time.

Further, the leaf spring portion 19 holds the valve body 18 in the closed position when the pressure received by the valve body 18 is 2 kg/cm ² or less, and when the pressure received by the valve body 18 is higher than that, the leaf spring portion 19 moves the valve body 18 as shown in FIG. The width of the leaf spring portion 19 is set so as to provide a spring pressure that causes the valve to move to the position shown by the imaginary line and open the valve.

On the other hand, the annular support part 25 of the opening/closing valve is provided with a cutting part 26 on the opposite side of the leaf spring part 19 so that it can be easily attached into the cylindrical body 13 of the vent hole 12.

This on-off valve 20 and the upper wall 15 are
It is clamped and fixed between the upper wall fixing part 14 of the upper end of the cylinder body 13 and the upper end of the inner cylinder 21 which is fitted and screwed together from the lower end of the vent hole 12.

The procedure for molding the mold 10 using the mold making apparatus 1 using the vent hole 12 configured as described above will be explained based on FIGS. 7 and 8.

FIG. 7 is a cross-sectional view showing the foundry sand filling process;
An injection port 5 for filling molding sand is provided in the upper mold upper wall 3a of the mold 2 of the mold making apparatus 1, and a plurality of air vent holes 6 are provided in the walls of the upper mold 3 and the lower mold 4. be.

A vent hole 12 is fitted into each air vent hole 6, and the upper wall 15 of the vent hole 12 is substantially flush with the inner surface 7 of the mold.

Molding sand 11 mixed with a binder such as phenolic resin is filled into the mold cavity 2a through the injection port 5 of the upper mold upper wall 3a together with compressed air 8 having a pressure of 3 kg/cm ² . At this time, the valve body 18 of the on-off valve 20 is in contact with the lower surface of the upper wall 15 of the vent hole 12.
receives the pressure of the compressed air 8 and opens the valve against the spring pressure of the leaf spring portion 19 constituting the valve closing spring.
Move to the position indicated by the imaginary line in the figure.

As a result, the sealing of the vent hole 16 is released, and the compressed air 8 in the mold cavity 2a is released into the vent hole 1.
Since the molding sand 11 is discharged from the air vent hole 6 through the inside of the cavity 2a, the molding sand 11 in the cavity 2a is filled with high density.

When the filling of the foundry sand 11 is completed, as shown in ^FIG . The mold 10 is formed by hardening the molding sand 11 by reacting with the binder.

At this time, since the filling pressure of the hardening gas 9 is lower than the spring pressure of the leaf spring part 19 of the on-off valve 20, the valve body 18 is held in the closed position by the leaf spring part 19, and the vent hole 16 is sealed. Ru.

As a result, the hardening gas 9 does not flow out of the mold cavity 2a, but is spread to every corner of the cavity 2a due to the filling pressure, reacts with the binder, and can harden all the molding sand 11 inside the cavity 2a.

When the hardening of the molding sand 11 is completed, the upper mold 3 and the lower mold 4
is opened, the mold 10 is taken out, and the molding is completed.

FIG. 3 shows a second embodiment of the present invention, in which a disc-shaped valve body 18 is brought into contact with the lower surface of the upper wall 15, and a leg portion 18a extends downward from the center of the valve body, and the cylindrical body of the vent hole 12 is A through hole 23 is provided in the center of the spring support member 22 fitted to the lower end of the spring support member 13, and the leg portion 18a is slidably supported in the through hole 23. A valve-closing spring 19 made of a compression coil spring is installed between the valve body 18 and the spring support member 22, and the valve body 18 is elastically biased toward the upper wall 15 to form a ventilation hole 16 formed through the upper wall 15. It is configured to seal.
Further, a communication hole 24 is provided in the spring support member 22 so that the ventilation hole 16 and the lower outside of the vent hole 12 can communicate with each other via the ventilation path 17 in the cylinder body 13.

FIG. 4 shows a third embodiment, in which a vent hole 16 is formed by an annular slit in the upper wall 15 of the vent hole 12, and a spring support fitted to the lower end of the cylinder body 13. A valve closing spring 19 made of a compression coil spring is mounted between the member 22 and the upper wall 15.

This valve closing spring 19 has a coil diameter of an annular ventilation hole 16.
A ring-shaped valve body 18 having the same diameter is integrally formed at the upper end.
The mounting position of the valve closing spring 19 is adjusted so that the annular vent hole 16 is sealed by the ring-shaped valve body 18.

In addition, since the upper wall 15 has an inner disk portion 15a and an outer annular portion 15b separated by an annular ventilation hole 16, the inner disk portion 15a is connected to the column portion 22a extending upward from the spring support member 22. However, when the inner disk portion 15a and the outer annular portion 15b are partially connected, it is not necessary to extend the column portion 22a upward from the spring support member 22.

5 and 6 show Example 4, FIG. 5 is a partially cutaway perspective view of the vent hole, and FIG. 6 is a bottom view thereof.

The upper wall 15 of this vent hole 12 is as shown in Example 1.
As in the above case, the upper wall 15 is clamped and fixed between the upper end of the inner cylinder 21 fitted from the lower end inside the cylinder main body 13 and the upper wall fixing part 14 at the upper end of the cylinder main body 13.

A spring fixing part 21a is formed at the lower end of the inner cylinder 21, and an on-off valve 20 made of a thin plate of stainless steel spring is attached so as to be able to seal the air passage 17 in the vent hole 12.

This on-off valve 20 is integrally constructed with a leaf spring 19 by protruding a part of the periphery of a circular valve body 18, and a part near the tip of the leaf spring 19 is attached to a spring fixing part 21a at the lower end of the inner cylinder 21. It's secured with screws. At this time, by adjusting the width and length of the leaf spring 19, when the pressure received by the valve body 18 is the hardening gas 9 filling pressure, the valve body 18 is held in the closed position and the ventilation passage 17 is sealed. The spring pressure of the plate spring 19 is set so that when the molding sand 11 is filled with pressure, the valve body 18 is moved to the position shown in the imaginary diagram in FIG. 5 and the seal is released.

[Brief explanation of the drawing]

1 to 6 show embodiments of the present invention, FIG. 1 is a partially cutaway perspective view of the vent hole of Embodiment 1, FIG. 2 is a plan view of the on-off valve of Embodiment 1, and FIG. 3 4 is a sectional view of the main part of the vent hole of Example 2, FIG. 4 is a view equivalent to FIG. 1 of Example 3, FIG. 5 is a view equivalent to FIG. 1 of Example 4, and FIG. 6 is a bottom view of Example 4. It is.
Figure 7 is a sectional view showing the molding sand filling process of the mold making equipment, Figure 8 is a sectional view showing the hardening gas blowing process of the mold making equipment, and Figure 9 is a view equivalent to Figure 1 showing a conventional vent hole. It is. 1... Mold making device, 9... Curing gas, 11...
...Casting sand, 13...Cylinder body, 15...Top wall, 16
...Vent hole, 17...Vent passage, 18...Valve body, 1
9... Valve closing spring, 20... Opening/closing valve.

Claims (1)

[Claims for Utility Model Registration] 1. An upper wall 15 is provided at the upper end of the cylinder body 13, and a ventilation hole 16 is provided in the upper wall 15 to allow ventilation between the ventilation hole 16 and the opening at the lower end of the cylinder body 13. In the vent hole used in the blow-type mold making apparatus 1, which is communicated with the passage 17, an on-off valve 20 is attached to the lower end side of the upper wall 15, and this on-off valve 20 is connected to the vent hole 16 or the air passage 17. a valve body 18 that enables sealing;
The valve body 18 is composed of a valve closing spring 19 that elastically urges the valve body 18 toward the upper wall 15 side, and the spring setting pressure of the valve closing spring 19 is set by the casting sand 11.
A vent hole 2 for mold making characterized in that the pressure is set lower than the filling pressure and higher than the filling pressure of the foundry sand hardening gas 9.The vent hole 2 is formed by bringing the valve body 18 into contact with the lower surface of the upper wall 15 when the valve is closed. 16. The vent hole for mold making according to claim 1 of the registered utility model, characterized in that the vent hole 16 is configured to be sealable. 3. The vent hole for mold making according to claim 1 or 2, wherein the valve body 18 of the on-off valve 20 and the valve-closing spring 19 are integrally constructed.