JP2005138117A - Method and apparatus for manufacturing shell sand mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing a shell sand mold, wherein a shell sand hardening period of time is sufficiently shortened, and odor is reduced. <P>SOLUTION: A mold 1 is heated at a temperature higher than that at which thermosetting resin included in the shell sand 5 can harden, or at a temperature higher than that at which the resin starts hardening, and filled with shell sand 5. The shell sand 5 is hardened by passing superheated steam therethrough whose temperature is higher than that at which thermosetting resin included in the shell sand 5 can harden, or at a temperature higher than that at which the resin starts hardening. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a shell sand mold manufacturing method and apparatus used for casting, and in particular, shell sand mold manufacturing that can shorten shell sand mold molding time and reduce odor by hardening shell sand in a short time. The present invention relates to a method and an apparatus.

The shell sand mold is a kind of mold and is used for casting casting.
In general, shell sand molds are manufactured by filling shell cavities containing a thermosetting resin and foundry sand into mold cavities coated with a release agent, and then heating the mold to form shell sand. Is cured, and the cured shell sand is released from the mold.
Thus, when the mold is heated to harden the shell sand, the heat of the mold is first transferred to the part of the shell sand that contacts the mold, and then heat is transferred from this part to the other part of the shell sand. Therefore, it took a long time for the entire shell sand to be heated to a temperature higher than the temperature at which the thermosetting resin can be cured or to a curing start temperature.

  Therefore, in order to shorten the hardening time of the shell sand, a technique for hardening the shell sand by passing a gas such as high-temperature air as a heating medium in the shell sand (see Patent Document 1), or a mold filled with the shell sand. The technique (refer patent document 2) which hardens shell sand by blowing water vapor | steam inside is devised.

JP 2002-137044 A

JP 2000-107835 A

  In the case of the technique described in Patent Document 1 in which a high-temperature gas is passed through the shell sand as described above, the gas can be brought into contact with the entire shell sand. Heat was not easily transferred to the shell sand, and the hardening time of the shell sand could not be shortened sufficiently.

  In the technique described in Patent Document 2, water vapor is used as a heating medium, but because there is no preheating of the mold, or because the preheating temperature is lower than the temperature at which the thermosetting resin can be cured or the curing start temperature. The heat from the water vapor was absorbed by the mold, and the amount of heat transferred to the shell sand was reduced, and the hardening time of the shell sand could not be shortened sufficiently.

  Therefore, the present invention provides a shell sand mold manufacturing method and apparatus capable of sufficiently shortening the curing time of shell sand and reducing odor.

The shell sand mold manufacturing method and apparatus of the present invention for solving the above-described problems have the following characteristics.
That is, the shell sand mold manufacturing method of the present invention is such that shell sand filled in a mold heated to a temperature higher than the curing temperature of the shell sand resin or higher than the curing start temperature is equal to or higher than the curing temperature of the shell sand resin. Shell sand is hardened by passing superheated steam having a high heat capacity equal to or higher than the curing start temperature.
Specifically, the present shell sand mold manufacturing method includes a step of heating the mold to a temperature at which the shell sand resin can be cured or higher or a curing start temperature or more, and a step of filling the mold cavity with shell sand. Supplying superheated steam to the shell sand to harden the shell sand.
Thus, by using superheated steam as a heating medium, it is possible to shorten the time until the shell sand thermosetting resin is heated to a temperature at which the thermosetting resin of the shell sand is cured or above the curing start temperature. Sand curing time can be shortened.
In addition, by heating and holding the mold so that it is at or above the temperature at which the thermosetting resin of the shell sand can be cured or at the curing start temperature, the temperature at which the shell sand at the interface with the mold can be cured quickly. In addition to heating to the curing start temperature, the heat transmitted from the superheated steam to the shell sand is prevented from escaping to the mold 1 side, and the shell sand curing time is further shortened.
Furthermore, by blowing superheated water vapor, the shell sand mold at the room temperature in the center part away from the surface of the mold can be heated to a temperature that can be cured in a very short time or higher than the temperature at which curing can be started, or the shell sand mold. Is easy to mold.
Thereby, it is possible to greatly shorten the molding time of the shell sand in the cavity.

In addition, the shell sand mold manufacturing apparatus of the present invention includes a mold having a cavity filled with shell sand and a superheated steam generator for generating superheated steam, and the mold supplies superheated steam to the cavity. A supply path for discharging water vapor and a discharge path for discharging water vapor from the cavity are formed.
As a result, it becomes possible to supply superheated steam to the shell sand in the cavity, and shorten the time until the thermosetting resin of the shell sand is heated to a temperature at which it can be cured or above the curing start temperature. As a result, the hardening time of the shell sand can be shortened.
And it becomes possible to shorten significantly the molding time of the shell sand in a cavity.

Furthermore, a plurality of discharge paths are formed in the mold, and a pump for sucking superheated steam in the discharge direction is connected to at least a part of the discharge paths.
If there is a location in the cavity where it is difficult for superheated steam to pass due to the shape of the cavity, mold structure, etc., a discharge path connected with a pump that draws superheated steam in the discharge direction should be placed at that location. Thus, the amount of superheated steam supplied to the location can be increased and cured in the same fast time as the shell sand at other locations.
As a result, the hardening time of the shell sand in the cavity can be shortened as a whole, and the molding time of the shell sand mold can be shortened, and the odor generated when the resin hardens is sucked and discharged, so that the working environment is reduced. It can be significantly improved.

According to the present invention, the hardening time of the shell sand can be shortened, and the molding time of the shell sand in the cavity can be greatly shortened.
Also, even if there is a place where superheated steam is difficult to pass through in the cavity due to the shape of the cavity and the mold structure, etc., the shell sand molding time in the cavity is shortened as a whole, and the molding time of the shell sand mold is reduced. In addition, the working environment can be remarkably improved because the odor generated when the resin is cured is sucked and discharged.

Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.
First, the shell sand mold manufacturing apparatus of the present invention will be described.
As shown in FIG. 1, the shell sand mold manufacturing apparatus includes a mold 1 composed of an upper mold 1 a and a lower mold 1 b, and a superheated steam generator 2 that generates superheated steam. Is provided with a blow plate 4.

The superheated steam generator 2 and the mold 1 are connected by a blower pipe 3 via a blow plate 4, and the superheated steam generated by the superheated steam generator 2 is formed on the blowplate 4 from the blower pipe 3. The air is sent to the mold 1 through the air passage 41.
In addition, superheated steam means what heated further saturated steam, and raised it to the temperature more than the saturation temperature, for example, steam higher than 100 degreeC by atmospheric pressure turns into superheated steam.

A cavity 11 filled with shell sand 5 is formed in the mold 1, and the cavity 11 is connected to a blower path 41 of the blow plate 4 by a plurality of supply paths 12 formed in the mold 1. Yes. Here, “shell sand” refers to “resin coated sand”.
A plurality of discharge paths 13 extending from the cavity 11 to the opposite side of the supply path 12 are formed in the mold 1.
In addition, although the supply path | route 12 and the discharge path | route 13 form multiple paths in this embodiment, it is also possible to form only one path | route.

  In the shell sand mold manufacturing apparatus configured as described above, the superheated steam generated by the superheated steam generator 2 is blown to the supply path 12 through the blower pipe 3 and the blower path 41, and the shell sand 5 filled in the cavity 11 is used. After passing, it is discharged to the outside through the discharge path 13.

The shell sand 5 includes foundry sand and a thermosetting resin as a shell sand resin. When the shell sand 5 is heated, the thermosetting resin hardens, and the shell sand 5 formed into a predetermined shape is obtained. It hardens in that shape.
In the shell sand mold manufacturing apparatus, when the superheated steam passes through the cavity 11, the shell sand 5 filled in the cavity 11 is heated and hardened.
Here, “shell sand resin” refers to “resin used for resin-coated sand”.

Next, the flow at the time of manufacturing a shell sand mold using this shell sand mold manufacturing apparatus will be described. Here, the “shell sand mold” refers to a “mold”.
As shown in FIG. 2, when the shell sand mold is manufactured, the mold 1 is first heated to a predetermined temperature (S01), and the upper mold 1a and the lower mold 1b of the mold 1 are closed (S02). ) The shell sand 5 is filled into the cavity 11 of the closed mold 1 (S03).

Next, superheated steam is generated by the superheated steam generator 2, and superheated steam is supplied into the cavity 11 (S04). The superheated steam supplied into the cavity 11 passes through the shell sand 5 and is discharged from the discharge path 13 to the outside.
The supply of superheated steam is continued until the shell sand 5 is hardened.

After the shell sand 5 is hardened, the supply of superheated steam is stopped, the mold 1 is opened (S05), and the work (hardened shell sand 5) is taken out (S06).
Thereafter, the steps from S02 to S06 are repeated while holding the mold 1 at a predetermined heating temperature.

  Here, the time from filling the shell sand 5 into the cavity 11 and starting the supply of superheated steam until the shell sand 5 is cured is equal to or higher than the temperature at which the thermosetting resin contained in the shell sand 5 can be cured. The time until the thermosetting resin starts to be cured until the end of the curing is added to the time until it is heated to the curing start temperature or higher.

In this shell sand mold manufacturing apparatus, “superheated steam” is used as the heating medium of the shell sand 5, because the use of superheated steam as the heating medium increases the temperature of the object to be heated quickly.
For example, as shown in FIG. 3, when a workpiece that is an object to be heated is heated using a high-temperature gas such as high-temperature air in the technique described in Patent Document 1 as a heating medium, the temperature of the workpiece is Gradually increases with time, and reaches the target temperature T at time t2 from the start of heating.

On the other hand, when superheated steam is used as the heating medium, the temperature suddenly rises from the start of heating and reaches the target temperature at time t1.
The time t1 when using superheated steam is about one tenth of the time t2 when using high-temperature gas.

  As described above, when the superheated steam is used as the heating medium, the temperature rise rate can be remarkably increased. Therefore, until the thermosetting resin of the shell sand 5 is heated to a temperature at which the thermosetting resin is cured or higher than the curing start temperature or higher. Can be shortened, and as a result, the hardening time of the shell sand 5 can be shortened.

Moreover, the temperature of the superheated steam supplied into the cavity 11 is set to be equal to or higher than the temperature at which the thermosetting resin of the shell sand 5 can be cured or the temperature at which the curing starts. .
That is, in this shell sand mold manufacturing apparatus, the heat from the superheated steam to be passed is conducted to the shell sand 5 so that the shell sand 5 is cured, so the superheat at the time when it is supplied into the cavity 11 is performed. The temperature of the water vapor is set to be higher than the temperature at which the thermosetting resin can be cured or the curing start temperature.

In addition, the temperature of the mold 1 that is heated before the shell sand 5 is filled is also set to be equal to or higher than the temperature at which the thermosetting resin of the shell sand 5 can be cured or higher than the curing start temperature for the following reason. doing.
That is, if the heating temperature of the mold 1 is lower than the temperature at which the thermosetting resin can be cured or the curing start temperature, the heat of the mold 1 is absorbed by the shell sand 5 filled in the cavity 11 and the temperature decreases. The temperature at the interface with the mold 1 is also lower than the curing temperature or the curing start temperature. As it is, the shell sand 5 at the interface with the mold 1 is not cured.
Therefore, in order for the shell sand 5 to start hardening, the heat from the supplied superheated steam is transmitted to the shell sand 5 so that the shell sand 5 at the interface with the mold 1 can be hardened or the hardening start temperature. However, it takes a long time for the shell sand 5 to harden.
Furthermore, when the heating temperature of the mold 1 is lower than the temperature at which the thermosetting resin can be cured or the curing start temperature, the heat transferred from the superheated steam to the shell sand 5 escapes to the mold 1 side. It takes time to heat the shell sand 5 to a temperature at which the shell sand 5 can be cured or above the curing start temperature.

  Therefore, in the present shell sand mold manufacturing apparatus, the shell sand 5 at the interface with the mold 1 is heated to a temperature at which it can be hardened quickly or to a temperature at which the hardening is started, and the heat transferred from the superheated steam to the shell sand 5 is increased. In order to prevent escape to the mold 1 side, the mold 1 is heated and held so that the heating temperature of the mold 1 is not less than the temperature at which the thermosetting resin of the shell sand 5 can be cured or not less than the curing start temperature. .

As described above, the curing time of the shell sand 5 is shortened by setting the preheating temperature of the mold 1 and the temperature of the superheated steam to be higher than the temperature at which the thermosetting resin of the shell sand 5 can be cured or higher than the curing start temperature. It is possible to do.
Note that, as shown in FIG. 4, the curing time of the thermosetting resin of the shell sand 5 (indicated by the gelation time in FIG. 4) becomes shorter as the temperature becomes higher. It is desirable to raise the preheating temperature of the mold 1 and the temperature of the superheated steam so that the characteristics of the resin do not change.

  Next, Table 1 shows the result of comparison of the hardened state of the shell sand 5, that is, the moldability of the shell sand 5 filled in the cavity 11, depending on whether or not superheated steam is used and the heating temperature of the mold 1. Show.

The mold temperatures Ta, Tb, and Tc in Table 1 are all higher than the temperature at which the thermosetting resin of the shell sand 5 can be cured or the curing start temperature, and are higher in the order of Ta <Tb <Tc.
Further, ta, tb, tc, td, and te indicating the supply time of superheated steam or the in-mold holding time of the workpiece are longer in the order of ta <tb <tc <td <te.

As can be seen from Table 1, in the case where superheated steam is used as the heating medium and in the case where it is not used, molding is possible when superheated steam is used at all mold temperatures Ta, Tb, and Tc. It is confirmed that the shortest time is considerably shortened.
Moreover, it is confirmed that the shortest time that can be formed becomes shorter as the mold temperature Ta, Tb, and Tc becomes higher in both cases of using superheated steam and not using it.
Then, by using superheated steam as the heating medium and setting the heating temperature of the mold 1 to the highest Tc, the shell sand 5 can be formed in a short time such as ta and tb.

Next, a second embodiment of the shell sand mold manufacturing apparatus will be described.
The shell sand mold manufacturing apparatus shown in FIG. 5 further includes a suction exhaust path 14 as an exhaust path from the cavity 11 in the mold 1 of the shell sand mold manufacturing apparatus shown in FIG.
The suction / exhaust path 14 is connected to the suction pump 7 via the surge tank 6, and is vacuumed by the suction pump 7.

When the shell sand mold is formed, depending on the shape of the cavity 11, the structure of the mold 1, or the like, there may be a portion in the cavity 11 where it is difficult for superheated steam to pass.
Since the hardening time of the shell sand 5 becomes long in such a place where the superheated steam is difficult to pass, the molding time of the shell sand 5 is also extended as a whole.

Therefore, in the shell sand mold manufacturing apparatus of this embodiment, the suction exhaust path 14 is provided at a location where it is difficult for superheated steam to pass through as it is, and the amount of superheated steam supplied to the location is increased by vacuum suction. It is made to harden in the same fast time as the shell sand 5 of the location.
That is, the suction / discharge path 14, which is a discharge path connected to the suction pump 7 that sucks the superheated steam in the discharge direction, is disposed in the cavity 11 at a position where it is difficult for the superheated steam to pass through. The amount of superheated steam supplied can be increased and cured in the same fast time as shell sand in other places.
Thereby, the hardening time of the shell sand 5 in the cavity 11 can be shortened as a whole, and the molding time of the shell sand mold can be shortened.
Note that the suction / exhaust passages 14 for performing vacuum suction can be provided at a plurality of locations as appropriate.

It is the schematic which shows the shell sand type | mold manufacturing apparatus of this invention. It is a figure which shows the flow of the shell sand mold manufacturing method of this invention. It is a figure which shows the raise degree of the workpiece | work temperature by the case where superheated steam is used as a heating medium, and the case where high temperature gas is used. It is a figure which shows the change of the gelatinization time with the temperature of the thermosetting resin of shell sand. It is the schematic which shows 2nd embodiment of a shell sand type | mold manufacturing apparatus.

Explanation of symbols

1 Mold 2 Superheated Steam Generator 5 Shell Sand 11 Cavity 13 Exhaust Route

Claims (4)

  Passing superheated steam at a temperature higher than the setting temperature of the shell sand resin or higher than the starting temperature of the shell sand resin through the shell sand filled in the mold heated to a temperature higher than the setting temperature of the shell sand resin or higher than the starting temperature of the setting. The shell sand mold manufacturing method characterized by hardening shell sand.   The step of heating the mold to a temperature at which the shell sand resin can be cured or above the curing start temperature, the step of filling the mold cavity with shell sand, and supplying superheated steam to the filled shell sand A shell sand mold manufacturing method comprising: a step of curing. A mold having a cavity filled with shell sand, and a superheated steam generator for generating superheated steam,
The shell sand mold manufacturing apparatus, wherein a supply path for supplying superheated steam to the cavity and a discharge path for discharging superheated steam from the cavity are formed in the mold. The shell sand mold manufacturing apparatus according to claim 3, wherein a plurality of discharge paths are formed in the mold, and a pump for sucking superheated steam in the discharge direction is connected to at least a part of the discharge paths. .

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