Abstract:
A method of neutralizing an amine gas odor in a cold box process, and an amine gas generator using the method are disclosed. The method includes: making molding sand by mixing sand and forming resin; putting the molding sand into a mold; hardening the molding sand by injecting an amine gas into the molding sand in the mold; and removing an amine gas odor remaining in the mold by injecting an amine gas odor neutralizer into the mold. Accordingly, it is possible to inject an amine gas odor neutralizer in casting of a core or a mold in order to reduce the amine gas odor that remains and leaks through a gap of a mold in the casting. Further, an odor neutralizer is immediately injected simultaneously with discharging of an amine gas, so it is possible to simply remove an odor.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of Korean Patent Application No. 10-2015-0011241 filed on Jan. 23, 2015, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a method of neutralizing an amine gas odor in a cold box process and a gas generator using the method. More particularly, the present invention relates to a method of neutralizing an amine gas odor in a cold box process that injects an odor neutralizer for an amine gas after hardening in order to reduce the amine gas odor that remains or leaks through a gap of a mold in the processing of manufacturing a core or a mold, and an amine gas generator using the method. 
     BACKGROUND OF THE INVENTION 
     A mold used for making the shape of a hole for manufacturing a hollow part such as a column in general casting is called a core. Casting for manufacturing a hollow cast is made by putting a core into a mold, injecting molten metal into the mold, taking out the cast and the core from the mold after the molten metal hardens, and then separating the core from the cast. 
     A core or a mold for casting is manufactured, for example, by making molding sand, in which dry sand and a plurality of forming resins are uniformly mulled by a mixer, putting the molding sand into a mold, hardening the molding sand by injecting an amine gas into the molding sand in the mold, and taking out the hardened object. 
     Such a technique has been disclosed in Korean Patent No. 10-1131033, titled “Use of amine blends for foundry shaped cores and casting metals”. In this related art, phenolic resin and polyisocyanate are used as a forming resin, and molding sand is obtained by mixing the forming resin with sand. The molding sand is hardened at room temperature, using an amine blend as a hardener and a core or a mold made of polyurethane can be obtained through the hardening. This process is called a PUCB (Polyurethane Cold Box) process. 
     Hardening a core or a mold using an amine gas has various advantages, for example: it can be hardened at room temperature without heating at a high temperature, the hardening speed is higher than high-temperature hardening, and not only the surface of molding sand, but the entirety of the molding sand can be hardened. However, when an amine gas is used as a hardener, a worker may have difficulty in working due to the amine gas odor remaining after hardening or due to an amine gas leak through a gap of a mold. 
     Documents of Related Art 
     (Patent Document 1) Korean Patent No. 10-1131033 
     (Patent Document 2) Korean Patent Application Publication No. 10-2009-0011520 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose a method of neutralizing the odor of an amine gas for a cold box process that injects an odor neutralizer for an amine gas after hardening in order to reduce the odor of an amine gas that remains or leaks through a gap of a molding in a processing of manufacturing a core or a mold, and an amine gas generator using the method. 
     Further, the present invention provides a method of neutralizing an odor of an amine gas for a cold box process that can simply remove an odor by injecting an odor neutralizer directly into a mold simultaneously with discharge of an amine gas, and an amine gas generator using the method. 
     In order to achieve the objects of the present invention, there is provided a method of neutralizing an odor of an amine gas for a cold box process that includes: making molding sand by mixing sand and forming resin; putting the molding sand into a mold; hardening the molding sand by injecting an amine gas into the molding sand in the mold; and removing an amine gas odor remaining in the mold by injecting an amine gas odor neutralizer into the mold. 
     In the removing the amine gas odor, the odor neutralizer may be injected into the mold simultaneously with discharging of the amine gas to the outside from the mold and an amount of the odor neutralizer injected may be 5 to 15 parts by weight based on 100 parts by weight of the amine gas. 
     In order to achieve the objects of the present invention, there is provided an amine gas generator that includes: an amine supplier supplying a stored amine gas; an odor neutralizer supplier supplying an odor neutralizer for removing the amine gas odor; an injection line through which the amine gas or the odor neutralizer is injected with compressed air into a mold; a regulator disposed in the injection line and maintaining an injection pressure of the compressed air at a predetermined level; a first valve disposed between the amine supplier and the injection line and stopping or passing the amine gas; and a second valve disposed between the odor neutralizer supplier and the injection line and stopping or passing the odor neutralizer. 
     The injection line may be divided into a gassing line through which the amine gas is injected with heated-compressed air into the mold and a purging line through which the odor neutralizer is injected with heated-compressed air into the mold, and the regulator may be composed of a first regulator disposed in the gassing line and maintaining injection pressures of the amine gas and the compressed air at predetermined level and a second regulator disposed in the purging line and maintaining injection pressures of the odor neutralizer and the compressed air at predetermined levels. 
     The amine gas generator may further include a third valve disposed in the gassing line and stopping or passing the compressed air and a fourth valve disposed in the purging line and stopping or passing the compressed air, and may further include a first check cylinder disposed in the gassing line for checking a supply amount of the amine gas and a fourth valve disposed in the purging line for checking a supply amount of the odor neutralizer, and the second valve may open simultaneously with closing of the first valve so that the odor neutralizer is supplied. 
     The first valve may have a first valve timer for adjusting opening and closing of the first valve at predetermined times and the second valve may have a second valve timer for adjusting opening and closing of the second valve at predetermined times. The amine gas generator may further include an air tank supplying the compressed air and an air heater heating the compressed air discharged from the air tank at 40 to 100° C. 
     According to the present invention, it is possible to inject an amine gas odor neutralizer after hardening in order to reduce the amine gas odor that remains and leaks through a gap of a mold in a process of manufacturing a core or a mold. 
     Further, an odor neutralizer is immediately injected simultaneously with discharging of an amine gas, so it is possible to simply remove an amine gas odor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a view of an amine gas generator according to a first embodiment of the present invention; 
         FIG. 2  is a view of an amine gas generator according to a second embodiment of the present invention; and 
         FIG. 3  is a flowchart illustrating a method of neutralizing an amine gas odor according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a method of neutralizing an amine gas odor for a cold box process according to the present invention and amine gas generators  100  and  200  using the method will be described in detail with reference to the accompanying drawings. 
     First, as shown in  FIG. 1 , an amine gas generator  100  according to a first embodiment includes an amine gas supplier  110  storing an amine gas, an odor neutralizer supplier  120  supplying an amine gas odor neutralizer, and a gassing line  130  and a purging line  140  through which an amine gas is injected into a mold  10 . 
     An amine gas in the amine gas supplier  110  is supplied to the mold  10  through the gassing line  130 . A first regulator  131  connected to an air tank  150  and receiving compressed air from the air tank  150  to maintain the pressure of injected amine gas at a predetermined level is disposed in the gassing line  130 . 
     As compressed air passes through the first regulator  131  from the air tank  150  for supplying the compressed air, the first regulator  131  adjusts the pressure of the compressed air to a predetermined level, and when the compressed air is sent into the mold  10 , an amine gas is supplied into the mold  10  with the compressed air by the pressure of the compressed air. 
     The generator further includes an air heater  151  that heats the compressed air from the air tank  150  at 40 to 100° C., when it flows into the gassing line  130 . When the temperature of the compressed air is lower than 40° C., an odor neutralizer may turn to liquid, and when it is higher than 100° C., the amine generator  100  may be damaged. Accordingly, it is important to maintain and supply compressed air at an appropriate temperature using the air heater  151 . 
     A first valve  133  stopping/passing an amine gas is disposed between the amine supplier  110  and the gassing line  130 . When the first valve  133  is open, an amine gas is supplied to the gassing line  130  from the amine generator  110 , and when the first valve  133  is closed, an amine gas is not supplied to the gassing line  130  from the amine supplier  110 . The first valve  133  has a first valve timer  133   a  that opens/closes the first valve at predetermined times. 
     A third valve  135  that opens/closes the gassing line  130  is disposed in the gassing line  130 . The third valve  135  opens or closes to adjust the amount of the compressed air that has passed through the first regulator  131 , so the compressed air and the amine gas that are supplied into the mold  10  are adjusted. The third valve  135  may have a third valve timer  135   a  that controls opening/closing of the third valve  135  at predetermined times. 
     The supply amount of an amine gas adjusted by the first valve  133  can be checked through a first check cylinder, if necessary. The check cylinder comes from the gassing line  130  and it is possible to check the supply amount of an amine gas in real time, using a graduation marked on the first check cylinder. 
     A second regulator  141  that maintains the compressed air from the air tank  150  at a predetermined pressure is disposed in the purging line  140 . Similar to the first regulator  131 , as compressed air passes through the second regulator  141  from the air tank  150 , the second regulator  131  adjusts the pressure of the compressed air to a predetermined level, and when the compressed air is sent into the mold  10 , an odor neutralizer is supplied into the mold  10  with the compressed air by the pressure of the compressed air. 
     A second valve  143  stopping/passing an odor neutralizer is disposed between the amine neutralizer supplier  120  and the purging line  140 . Similar to the first valve  133 , when the second valve  143  is open, an odor neutralizer is supplied into the purging line  140 , and when the second valve  143  is closed, an odor neutralizer is not supplied. The second valve  143 , similar to the first valve  133 , has a second valve timer  143   a.    
     A fourth valve  145  that opens/closes the purging line  140  is disposed in the purging line  140 . The fourth valve  145  adjusts supply and stoppage of the compressed air that has passed through the second regulator  141 . The fourth valve  145  may have a fourth valve timer  145   a  that controls opening/closing of the fourth valve  145 . 
     The supply amount of the odor neutralizer adjusted by the third valve  143  and the fourth valve  145  can be checked by the second check cylinder, similar to the first check cylinder. 
     When the amount of an amine gas supplied to the mold  10  and checked through the first check cylinder reaches to a predetermined level, the supply of the amine gas is stopped by the first valve  133  or the third valve  135 . Further, when the information about the supply amount of the amine gas is transmitted to a controller  160  or a user inputs it to the controller  160 , the controller  160  sends a signal to the second valve  143  or the fourth valve  145  so operate them. When the supply of the amine gas is stopped, the compressed air and the odor neutralizer are injected into the mold  10 . 
     The second valve  143  or the fourth valve  145  may operate such that the odor neutralizer is injected in an amount of 5 to 15 parts by weight based on 100 parts by weight of amine gas. When the amount of the odor neutralizer injected is less than 5 parts by weight, it cannot sufficiently neutralize remaining amine gas, and when the amount of the odor neutralizer injected is more than 15 parts by weight, it can sufficiently remove the odor of amine gas, but the cost is high. Accordingly, the odor neutralizer may be injected in the amount of 5 to 15 parts by weight based on 100 parts by weight of amine gas 
     An amine gas generator  200  of a second embodiment is the same as the first embodiment in the configuration of the amine supplier  210  and the odor neutralizer supplier  220 , but different in that the gassing line  130  and the purging line  140  are integrated into one injection line  230 . 
     An amine gas in the amine gas supplier  210  is supplied to the mold  10  through the injection line  230 . A regulator  230  connected to an air tank  250  to maintain the injection pressure of the amine gas at a predetermined level and receiving compressed air heated by the air tank  250  and an air heater  251  is disposed in injection line  230 . When compressed air is supplied into the mold  10  through the regulator  231 , an amine gas is supplied into the mold  10  or stopped by the amine supplier  210  and the first valve  233  in the injection line  230 . The odor neutralizer to be supplied to the injection line  230  is adjusted by a second valve  235  disposed between the odor neutralizer supplier  220  and the injection line  230  and stopping/passing the odor neutralizer. 
     When a necessary amount of an amine gas is injected into the mold  10 , the supply of the amine gas to the injection line  230  through the first valve  233  is stopped and the second valve  235  is opened, so the odor neutralizer is injected with compressed air into the mold  10  and neutralizes the amine gas odor. The first valve  233  and the second valve  235  may be simultaneously controlled by a controller  260 . The first valve  233  and the second valve  235  may have a first valve timer  233   a  and a second valve timer  235   a , respectively. 
     In the related art, when an amine gas supply is stopped, only compressed air is supplied into the mold  10  to discharge the amine gas in the mold to the outside. However, when only compressed air is supplied, as described above, the amine gas remaining in the mold  10  and the amine gas leaking through a gap of the mold gives off a bad smell, so a worker feels discomfort. However, according to the present invention, it is possible to reduce an amine gas odor by supplying an odor neutralizer with compressed air. 
     A method of neutralizing an amine gas using the amine gas generators  100  and  200  is as follows. 
     As shown in  FIG. 2 , molding sand  30  is made by mixing sand and forming resin (S 1 ). 
     The sand and the forming resin are used as materials for manufacturing a core or a molding and they are mulled by a blender such as a mixer, thereby making the molding sand  30 . 
     The molding sand  30  is put into the mold  10  (S 2 ). 
     The molding sand composed of the sand and the forming resin is put into the mold  10  fitting to the shape of a core or a mold. The mold  10  is divided left and right and the molding sand  30  is put into the mold  30  through the upper portion of the mold  10 . An amine gas or an odor neutralizer is also injected through the portion for injecting the molding sand  30 . 
     The molding sand  30  is hardened by injecting an amine gas into the mold  10  (S 3 ). 
     Compressed air and an amine gas are injected into the mold  10  having the shape of a core or a mold and filled with the molding sand  30 , through the same inlet of the mold  10 . When the amine gas is injected as a catalyst for the molding sand  30  composed of the sand and the forming resin, the forming resin hardens by reacting with the amine gas. When the molding sand is hardened by amine gas, a core or a mold made of polyurethane can be finally obtained. 
     The amine gas odor is removed by injecting an odor neutralizer (S 4 ). 
     After the molding sand  30  hardens in the mold  10 , the amine gas is discharged into a neutralizing tank  50 , and is then neutralized in the neutralizing tank  50  and discharged to the atmosphere. Some of the amine gas may remain in the mold  10  or the amine gas may leak through a gap of the mold  10  while it flows into the neutralizing tank  50 , and in this case, the amine gas emits a bad smell discomforting a worker. Accordingly, with discharging of the amine gas, compressed air and an odor neutralizer are injected into the mold  10  through the inlet through which the amine gas was injected. When an odor neutralizer is injected through the inlet of the mold  10 , it neutralizes the amine gas remaining in the mold  10  or in the gap of the mold  10 , so the distinct odor of ammonia is reduced. Accordingly, a worker does not feel excessively uncomfortable. 
     Since the odor neutralizer is injected into the mold  10  simultaneously with discharging of the amine gas, there is no additional step and there is no difference between the process time and the process times of the related art, so a worker is not troubled. 
     In some cases, it may be possible to additionally neutralize the amine gas discharged to the atmosphere through the neutralizing tank  50  by additionally installing the odor neutralizer supplier  120  to the neutralizing tank  50 . 
     The odor neutralizer may be injected in an amount of 5 to 15 parts by weight based on 100 parts by weight of the amine gas. When the amount of the odor neutralizer injected is less than 5 parts by weight, it cannot sufficiently neutralize the remaining amine gas, and when the amount of the odor neutralizer injected is more than 15 parts by weight, the odor neutralizer is too much in comparison to the remaining amine gas, so the odor neutralizer may be wasted. 
     When the amine gas in the mold  10  or in a gap of the mold  10  remains, a worker may be discomforted by the gas odor. However, as in the present invention, when an odor neutralizer is injected into the mold  10 , it neutralizes the amine gas remaining in the mold  10  or in the gap, so a worker can more easily work. Further, since the process of injecting an odor neutralizer is performed simultaneously with discharging of the amine gas from the mold  10 , there is no need for an additional process and the work time does not increase, so it is efficient. 
     Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.