JPS6027443A - Gas curing type molding method making combination use of suction means - Google Patents

Abstract

PURPOSE:To pack easily molding sand to the part except an air route and to increase the packing density near a blow nozzle with gas curing type molding by sucking the inside of a die cavity to a negative pressure simultaneously with sand blowing or after some time lag. CONSTITUTION:A blow head 2 holding internally sand mold 23 with respect to an upper die 6 suspended to a support 7 and a lower die 8 are brought into press contact with each other, the former by a press-contact head 1 and the latter by a clamping piston 16, thereby forming the cavity B in the dies. A blow nozzle 5 and a blow plate 4 are integrally attached to the head 2. The head 2 suspended by means of a spring 18 to a traversing carriage 3 is made freely movable upward and downward by the head 1 integral with a lifting cylinder. Sand packing is accomplished by introducing compressed air into the inside A of the head 1 as the air arrives at A' and blows the sand 23 in the head 2 into the cavity B through the nozzle 5. The back C of the mold 8, i.e., a suction circuit 13 is subjected to large volume of suction in short time by actuating the valve provided in the direction of a vacuum tank therefrom simultaneously with said blowing or during continuation of the blowing with some time lag.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas curing mold making method using a suction means.

Recently, a suction sand filling and suction gushing molding method has been proposed to compete with the conventionally known sand filling and pressurizing molding method, but the suction method has the following drawbacks. As a result of the experiment, one thing is clear.

(a) There is a direct air flow between the air vent side where the suction passes and the blow nozzle side where sand flows into the mold cavity. In some cases, sand is not filled at all in areas far from the air path.

rb) f The mold part near the low nozzle has a low sand filling density.

(c) The arrangement of air vents to improve sand filling is very complicated and requires several times the number of air vents compared to the blow-in type.

(d) The same tendency as above occurs when gas is vented by suction, as the mold does not harden outside the air flow path.
In order to ventilate gas evenly into the mold, it requires several times or more air vents than pressurized gashing.
In addition, there is a tendency for the arrangement of air vents to be contradictory to sand filling properties and gas permeability (i.e., if the air vent arrangement improves sand filling, the gas permeability effect worsens).
Air vent arrangement becomes more complicated.

(e) The curing time of the mold due to gutting is long.

(f) The maximum pressure difference with the atmosphere is 1 atm, and the dynamic pressure difference inside the mold cavity is about 0.5 atm or less, and even if a larger suction pressure is required, it cannot be supported. .

However, in mold making using the suction method, the part of the cavity far from the blow nozzle + 7) 9i [- can effect can be increased, and the clamping force for sealing the mold without leakage of the reaction gas can be increased by blowing ( The main advantage is that it is smaller than the pressurized type.

In order to eliminate the drawbacks of the conventional suction method, the present inventor has conducted various studies and experiments, and as a result has succeeded in developing a gas-curing mold making method that uses the suction means of the present invention. Although the configuration is specified in each claim, the actual method of the present invention #l! 1flI will be explained in detail based on the accompanying drawings.

In FIG. 1, a blow head 2 holding molding sand 23 is attached to a crimping head 1 with respect to an upper mold 6 suspended from an upper mold support 7.
The figure shows a state in which the lower mold 8 is pressed into contact with the flang piston 16 to form a cavity B in the mold.

Incidentally, the blow nozzle 5 and the blow grating 4 are integrally attached to the blow head 2, and the blow head is suspended on the traversing carriage 3 by a spring 18, and is movable up and down by the crimping head 1. It is constructed integrally with a lifting cylinder (not shown) for one crimping head.

Filling of sand into the mold cavity B is carried out in the state shown in FIG. That is, when compressed air stored in an air tank (not shown) is introduced into the crimping head A by pulp (not shown), it reaches the air channels A751 and A', and blows the sand 23 in the blow head 2 through the blow nozzle 5. Blow into cavity B in the mold. Simultaneously with this blowing, sand is thrown at a slight time difference, and while the blowing continues, the back side C1 of the lower mold 8 is immediately moved from the suction circuit 13 to the surge tank (not shown) kept at 1c. A large volume of suction is performed for a short period of time by activating a pulp (not shown) provided in the chamber. Depending on the shape of the cavity B in the mold, in order to improve the sand filling properties, the suction may be performed first using #F! beginning, then (
Cavity B (may also be filled with sand) by performing a blowing operation while suction is continuing (with a slight time difference).

After sand filling into the mold cavity B is completed, the internal pressure of the blow head 2 is returned to atmospheric pressure, and then the suppression of the blow head 2 by the crimping head 1 is released (the crimping head 1 is raised by the lifting cylinder). ), the blow head 2 is raised by the spring 18 and separated from the upper mold 6.

The two blow heads are moved out from between the crimping head 1 and the upper mold 6 by the traversing cart 3, and the blow head is removed! It replaces the tushing head 21.

Figure 2 is Gatsusing Head 21#! The state in which the EEfi head 1 is pressed against the upper mold B is shown.

Gutting for hardening the mold in the mold cavity B is performed in the state shown in FIG. That is, the low-pressure or micro-pressure curing gas introduced into the gushing path 22 from a gas generator (not shown) reaches the cavity E in the gushing head 21, and is further applied to the outer periphery and top of the mold extrusion/forming pin 20. It passes through the gap between the mold 6 and the blow hole F and the air bed (not shown) provided in the upper mold, and then passes through the n-mold. The waste gas that hardens the mold is passed through the air vent 9 of the lower mold 8 to C, and finally to the waste gas neutralization tank where it is purified.

At the same time as the above-mentioned pressurized gashing using the low-pressure or slight-pressure curing gas, or with a time difference, the back surface C of the lower mold, that is, the suction circuit 1
From step 3, suction is performed under negative pressure in the same manner as in the case of sand filling. Depending on the shape of the target or the arrangement of the air pen, the suction may be started first to ensure uniform gashing on the mold.
Suction gassing is performed by simply creating a negative pressure in the inner F mold 0 and the lower mold back space 0, or by releasing gas. Afterwards (with a time difference), low-pressure or micro-pressure hardening gas may be supplied to the mold (pressurization is applied) while suction continues.

The above-mentioned gassing head performs scavenging using a combination of pressure and suction in the same system as above, and the curing gas remaining in various places is removed with air. The scavenged curing gas is purified in a neutralization tank. After the purging is completed, the pressure contact between the gutting head and the lower mold is released, and the mold is taken out from the cavity B of the mold by the operation of the mold extrusion bins 10 and 20 in the space where the lower mold has descended. .

The method of the present invention performs barrel formation and operation as described above, and the effects achieved are as follows: (1) The above explanation was made with reference to the case of horizontally split molding; It can also be applied to split molds.

(2) In FIGS. 1 and 2, the suction path is introduced from the T-shaped mold, but it is also possible to introduce it only to the upper mold or to both the upper mold and the lower mold.

(3) In the example of vertical splitting as shown in Figure 3, the suction method fills the d part well with sand, but the filling is worse as it reaches bSa and the upper part, and the blowing method fills the albsc well but the d part. The filling may not be sufficient. The combined suction and blowing method compensates for this shortcoming, az bz ez d
Both can provide molds that are reliably filled.

(4) With suction only, the pressure difference between the blowing (pressurizing) side and the back of the mold (atmospheric pressure) is at most 1 atm, and the dynamic pressure difference inside the mold cavity is 0.5 atm or less. However, the combination method can create a large pressure difference, so it is possible to fill the sand incompletely, and it takes a long time for gassing, as well as poor hardening. Defects are eliminated.

(5) By using suction together, it is possible to maintain a substantially higher pressure difference within the mold cavity even if the air supply pressure is lowered compared to the conventional method using only blowing (pressurization). .

(6) During gassing, the suction action maintains the effect of preventing gas leakage from the mold cavity, while the gas is stopped in the mold cavity (Iill type) by pressurization.
When the mold is thoroughly hardened, the mold is completely filled.

Furthermore, since the pressure difference is larger than in the suction method alone, the tucking time is shortened and productivity is improved.

(7) The clamping force for sealing the mold must be increased as the air pressure for blowing (pressurization) is higher than atmospheric pressure in order to withstand the internal pressure inside the mold cavity. In the case of the suction method, the clamping force is small, but a minimum clamping force is required to open and close the heavy mold at a predetermined speed.

Therefore, as long as there is a Kranzka of this level, there is no need to increase the pressure (in the case of the combination method compared to the suction only method). Since the internal pressure is naturally lower in the combination method, the crankshaft can be smaller.

The higher the internal pressure, the higher the possibility of gas leakage, but there is no leakage because the blow head, gassing head, mold, and mold mating surfaces are sealed. Note that the seal is necessary not only for the pressurization method but also for the suction only method in order to prevent air from flowing in from an unspecified part, and there is no cost advantage between the two types of seals. Also, blowing (
When pressurization and suction are used in combination, the pressure difference can be made larger than when using only suction even if the internal pressure of the mold cavity is set to about atmospheric pressure.

Since the combination method can bring the internal pressure of the mold cavity close to atmospheric pressure, there is no need for sophisticated sealing as in the blowing (pressurization) method.

[9] The number of air vents depends on the blowing (pressurization) method and t1.
The air vent arrangement is simpler than the suction method.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional view showing the state in which the upper and lower molds are matched and the blow head is crimped to the back of the upper mold. Figure 3 is a partial cross-sectional view showing an example of vertical splitting. It is a diagram. In the figure, 1 is the crimping head, 2.51 is the blow head, 3 is the traversing trolley, 4.52uf is the losolate, and 5.53 is! Low nozzle, 6 is the upper mold, 7 is the upper mold support, 8 is the lower mold, 9.55B air vent, 10 is the extrusion bottle, 11.1
2.24.25.26 is a seal, 13 is a suction path, 14
Clamp table, 15Fi mold push-up cylinder, 1
6 is the clamp cylinder piston rod, 17 is the clamp cylinder, 18 is the spring, 19 is the mold extrusion cylinder, 20 is the mold extrusion/molding bottle, 21 is the f clamp head, 22 is the ff sink path, 26.54 is the mold Sand, 56.57 is a mold, and 58 is a mold. O 2 Ward Figure 3

Claims (1)

[Claims] (11) In gas-curing mold making, the inside of the mold cavity is suctioned to negative pressure at the same time as molding sand is injected or at a time difference, and molding sand is filled into the mold cavity. A gas-curing mold making method using a suction means. (2) The suction means according to claim 1, wherein the staggered suction is before or after blowing the molding sand. Gas-curing mold-making method used in combination. (3) In gas-curing mold-making, a suction means characterized by pressurized gassing of the reaction gas while suctioning the mold cavity filled with molding sand to negative pressure is used in combination. death,
Gas-curing mold making method.