JP2008012552A - Method and apparatus for producing molding sand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing molding sand for performing coating of raw material sand with resin, cooling and hardening of the resin at the most suitable timing. <P>SOLUTION: The method for producing the molding sand includes: charging the raw material sand into a kneading tank 3 based on a kneading tank temperature t1; supplying the resin into the sand based on a sand temperature st1; supplying hexa-water into the sand based on a peak loading current i1 of a stirring motor 6; supplying calcium stearate into the sand based on a sand temperature st2; and discharging the molding sand based on a lowered load current i2 and a sand temperature st3. The apparatus for producing the molding sand is characterized in that the stirring motor 6 for driving a stirring blades 4 and kneading tank rollers 5 is fitted to a top plate part of the kneading tank provided with a raw material sand charging hole 1a, a resin supplying hole 7, a calcium stearate supplying hole 8, a hexa-water supplying hole and a molding sand discharging hole 11, and in that a temperature detecting means for detecting the kneading tank temperature t1 and the sand temperatures st1, st2, st3 and a load current detecting means for the stirring motor 6 for detecting the peak loading current i1 of the stirring motor 6 and the lowered load current i2 added to the above sand temperature st3 are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a casting sand production method and apparatus for obtaining casting sand by melting and coating resin on raw sand such as new sand and recycled sand.

  Conventionally, when reclaiming casting sand, there is a method in which a stirring load value of a stirrer is measured, and a predetermined amount of a replenishing material is added to a kneading tank and kneaded so that the measured stirring load value becomes a desired value ( For example, see Patent Document 1). Also, there is a type that detects the load power value of the drive motor and discharges foundry sand having a necessary degree of kneading by continuously detecting that the load power value has reached a predetermined value or less for a predetermined time. . (For example, refer to Patent Document 2).

However, in Patent Document 1, an optimum fluidity is obtained by adding a replenishment material based on the stirring load value, that is, the fluidity of the foundry sand, and does not determine the timing of the kneading process of the foundry sand. Further, in Patent Document 2, since the load power value of the drive motor is based on the degree of kneading of all of the initial sand, intermediate sand, and kneaded sand, there is a problem that the discharge timing of the foundry sand is not necessarily optimized. Development of an apparatus for efficiently producing foundry sand by optimizing the timing of the entire processing process has been demanded.
JP-A-7-232233 JP-A-8-257679

  An object of the present invention is to provide a casting sand manufacturing method and an apparatus therefor capable of performing resin deposition, cooling, and hardening on raw material sand at an optimal timing.

  In the present invention, the raw material sand is put into the kneading tank based on the kneading tank temperature t1 detected by the temperature detecting means provided in the temperature-adjustable cylindrical kneading tank, and is detected by the temperature detecting means. The resin is supplied into the sand based on the sand temperature st1, the hexa water is supplied based on the peak load current i1 of the stirring motor detected by the load current detecting means, and further detected by the temperature detecting means. Steady feeding is performed based on the sand temperature st2, and the kneading process is completed based on the reduced load current i2 detected by the load current detection means and the sand temperature st3 detected by the temperature detection means, and the foundry sand is discharged. In the top plate of a cylindrical kneading tank equipped with a casting sand production method and a raw material sand inlet, resin supply port, steal supply port, hexa water supply port and casting sand discharge port Let A stirrer blade and a kneading roller for driving the kneading roller are attached, and the kneading tank temperature t1 for determining the sand charging timing and the sand temperature st1, st2 for determining the resin and steal supplying timing and the kneading treatment are completed. The temperature detecting means for detecting the sand temperature st3 which is one condition for determining the discharge of the foundry sand, the peak load current i1 of the stirring motor for determining the supply timing of the hexa water and the kneading process are completed, and the foundry sand A casting sand manufacturing apparatus provided with a load current detecting means of a stirring motor for detecting a reduced load current i2 applied to the sand temperature st3 condition for determining discharge, wherein in the casting sand manufacturing method, the steal supply is performed at the sand temperature st2 And kneading tank humidity ht1 is more preferable. Further, in the foundry sand production apparatus, the kneading tank is provided with a humidity detecting means for detecting the kneading tank humidity ht1, and the kneading roller is made of a spring material disposed at a position higher than the supply level of the raw material sand introduced into the kneading tank. It is more preferable if it is attached to the agitation motor via an attachment bracket.

  In the present invention, the load current detecting means detects the peak load current i1 and the reduced load current i2 flowing through the agitating motor, and the temperature detecting means detects the kneading tank temperature t1 or the sand temperatures st1, st2, st3 and detects them. Further, based on the kneading tank temperature t1 or the sand temperatures st1, st2, st3 and the detected peak load current i1 and the reduced load current i2 of the stirring motor, the raw material sand is charged, the resin is fed, the hexa water is fed, the steak is fed, and the kneading Since the processing is completed and the discharge of the foundry sand is controlled, each processing can be performed at an optimal timing, and the foundry sand can be manufactured efficiently and in a short time. In addition, since the foundry sand is discharged as soon as the sand treatment by the steak is completed, it is possible to prevent the resin attached to the sand from peeling off by repeating kneading more than necessary. For this reason, if it is incorporated in a casting system, the supply of foundry sand is stabilized and the molded product can be produced efficiently. Moreover, since the supply of foundry sand is stable, it is not necessary to store a large amount of foundry sand for backup, thus saving space.

  If the steal supply is based on the sand temperature st2 and the kneading tank humidity ht1, as in claim 2, the amount of water in the sand can be optimized for the steal treatment, so that the sand can be dispersed efficiently. Fluidity.

  As in claim 5, the kneading roller is attached to the agitating motor via a mounting bracket made of a spring material arranged at a position higher than the supply level of the raw material sand introduced into the kneading tank. Since the bracket does not touch the raw material sand, the fluctuation of the load current value of the stirring motor is limited mainly to the sand viscosity received by the stirring blade, and the sand viscosity can be detected with higher accuracy.

  In addition, since the mounting bracket is not subject to resistance by sand, the load on the agitation motor can be reduced and power consumption can be reduced. Can be reduced. In addition, since the mounting bracket is a spring material, the kneading roller does not apply excessive pressure to the sand, so it can be prevented from crushing the sand, and even if it hits the solidified sand attached to the tank, the spring material As a result, the kneading roller escapes, so that a large load is not applied to the stirring motor, and fluctuations in the load current of the stirring motor can be suppressed and power consumption can be reduced.

Next, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
In the figure, reference numeral 1 denotes a kneading machine for melt-coating a coating resin on a raw material sand. The kneading machine 1 has a stirring blade 4 for dispersing sand staying at the bottom and side of the kneading tank 3, and a kneading tank 3 A kneading roller 5 that rotates along the peripheral wall of the drum and presses the sand to adhere the resin, and a stirring blade 4 and a stirring motor 6 that rotates the kneading roller 5 are provided.

  Further, the kneading tank 3 has a temperature detecting means (not shown) for detecting the kneading tank temperature t1 or the sand temperatures st1, st2, st3, and a load for detecting a load current such as a peak load current i1 and a reduced load current i2 of the stirring motor 6. Current detection means and humidity detection means for detecting the kneading tank humidity ht1 are provided. The kneading tank temperature t1 or the sand temperatures st1, st2, st3, the peak load current i1, the reduced load current i2, and the kneading tank humidity. Based on ht1, etc., the steps from the introduction of raw material sand, the supply of additives such as resin, hexa water, and stekal to the completion of the kneading process to the discharge of foundry sand are controlled.

  Since the agitation motor 6 is provided at the upper part of the tank via a bearing 6a attached to the top plate portion of the kneading tank 3, it is possible to accurately prevent the fine powder of raw material sand from entering the bearing 6a.

  The kneading tank 3 is provided with a raw material sand inlet 1a provided on the top surface of the top plate and a casting sand outlet 1b formed on the peripheral wall, and a resin supply port 7 and a steak supply port on the top surface of the top plate. 8, an exhaust duct 9 and an inspection window 10 are provided. The kneading tank 3 is provided with cooling means including a cooling pipe and a cooling space (not shown) on the side wall and the bottom thereof so that the kneading tank temperature and sand temperature can be cooled. 2 is an open / close lid provided at the discharge port 1b, and 2a is a chute for guiding the discharge of the foundry sand. In addition, the steak supply port 8 is one in which calcium stearate (stekal) as a lubricant is weighed and supplied into the kneading tank 3, and the sand in which the resin is coated on the casting sand is dispersed by the stekal to impart fluidity. The

  The tank body of the kneading tank 3 is composed of a lining metal thin plate 3a made of stainless steel or iron and a structural metal plate 3b made of stainless steel, iron or the like, and between the lining metal thin plate 3a and the structural metal plate 3b. The cooling means is configured by arranging a cooling pipe for water cooling, a cooling space, etc. (not shown).

  The thin lining metal plate 3a is worn quickly, but the bottom of the kneading tank 3 is detachable so that the thin lining metal plate 3a can be replaced quickly. Even if the frequency of replacement is increased, the decrease in operating rate can be suppressed. Furthermore, by making the bottom of the kneading tank 3 detachable, not only maintenance and inspection work such as kneading rollers and stirring springs, but also replacement of these can be made extremely simple, reducing maintenance time and restarting in a short time. It will be possible to suppress a decrease in the operating rate.

  Further, the kneading roller 5 is a pair of rollers disposed at an interval of 180 ° on the output rotating shaft 15 of the stirring motor 6 suspended in the kneading tank 3 via the positioning block 20 and the mounting bracket 16. The mounting bracket 16 is made of a spring material, so that when the kneading roller 5 is subjected to a force for crushing sand, the kneading roller 5 is released by the elasticity of the spring material so that the sand is not crushed. . Due to this escape, a large load is not applied to the stirring motor 6, so that the load current of the stirring motor 6 can be prevented from greatly fluctuating and the power consumption can be reduced.

  Further, as shown in FIG. 5, the load current value of the agitating motor 6 detected by the load current detecting means is mainly the increase in sand viscosity due to the deposition of the resin to be kneaded and the decrease in sand viscosity due to the steak. Therefore, the supply of hexa water and the discharge of foundry sand are controlled based on the load current value and the sand temperature detected by the temperature detecting means.

  Further, the mounting bracket 16 is attached to the output rotary shaft 15 so as to be disposed above the supply level of the sand introduced into the kneading tank 3, and is not buried in the sand. The load current values such as the peak load current i1 and the reduced load current i2 of the stirring motor 6 detected by the means are mainly due to the viscosity of the sand applied to the stirring blade 4 immersed in the sand.

  Moreover, since the mounting bracket 16 is not immersed in the sand, the power consumption of the stirring motor 6 can be reduced, and the mounting bracket 16 is prevented from being worn out by the sand. The kneading roller 5 applies the compression action and the shearing action by pressing the sand against the side wall and performs kneading of the resin. The kneading roller 5 is not soaked deeply in the sand and is affected by the viscosity of the sand. It is difficult and the load current value of the stirring motor 6 does not fluctuate greatly.

  The stirring blade 4 is composed of an inner blade 4a that brings the sand staying in the tank side part to the center and a pair of scraping blades 4b that picks up the sand staying in the tank bottom, so that it depends on the viscosity of the sand. It is directly affected. The inward blades 4 a of the stirring blade 4 are a pair of members disposed at an interval of 180 ° on the output rotation shaft 15 of the stirring motor 6 suspended in the kneading tank 3. Further, the scraping blade 4b is also a pair disposed at 180 ° intervals on the output rotation shaft 15 of the stirring motor 6 suspended in the kneading tank 3, and by stirring the sand by these, The density is not biased.

  The arrangement position of the scraping blade 4b and the kneading roller 5 is shifted by about 60 °. The inward blade 4 a is attached between the scraping blade 4 b and the kneading roller 5, and is attached toward the approximate center of the output rotating shaft 15.

  Reference numeral 30 denotes an injection device that heats or cools the kneading tank 3 and the raw material sand by spraying room temperature air, cold air, hot air, or an appropriate combination thereof. The injection device 30 is attached to the body wall near the bottom of the kneading tank. A nozzle 30a that jets a medium such as room temperature air or cold air in a diagonally downward tangential direction and directly injects it into the raw material sand, and a nozzle 30b that jets hot air that is attached to the lower side wall of the kneading tank and heated by a heater. And a nozzle 30c that is attached to the bottom of the tank and injects normal temperature air or cold air upward and directly injects into the raw material sand, and the injection device 30 raises the temperature of the overcooled kneading tank 3 at the initial startup, The preheated sand is cooled to the processing temperature.

  Four nozzles 30a are arranged at equal intervals on the tank body wall, and the medium is ejected obliquely downward in a substantially tangential direction, whereby the sand at the bottom of the tank is stirred and suspended and the flow in the rotating direction of the stirring blade 4 is made. By promoting, the sand is diffused and flowed so that the medium is surely brought into contact with the sand grains, so that the transition to the predetermined temperature is rapidly performed. Also, one of the nozzles 30a is a hexa water supply port that switches the room temperature / cold air supply line to a hexa water supply line and injects hexa water into the raw material sand. Hexawater is a mixture of hexamethylenetetramine as a curing agent and cooling water. After the resin is melted and deposited on sand, the resin is sprayed with hexawater to accelerate curing and cooling of the resin. .

  In addition, two nozzles 30b are arranged at the lower part of the tank body wall so as to face each other with the output rotation shaft 15 therebetween, and air heated by the heater is fed into the kneading tank 3 to raise the temperature of the kneading tank 3 and sand. It is something to be made. The mounting position of the nozzle 30b is not limited to the lower part of the tank body wall, and may be the upper part of the kneading tank body wall or the top plate part. This is not a problem when the temperature of the kneading tank 3 is raised when the mounting position is limited to the lower part of the tank shell wall. However, when the temperature of the sand is adjusted by blowing hot air and room temperature air or cold air, hot air is blown into the sand. This is because when the direct injection is performed, the temperature of the sand partially rises and it is difficult to make the sand temperature uniform.

  Further, the nozzle 30c is a pair arranged with the output rotation shaft 15 interposed therebetween, and is used to move the sand to a predetermined temperature while agitating and floating the sand by directly spraying normal temperature air or cold air from the bottom of the tank into the sand. However, at the initial stage of the kneading process, when a small amount of raw material sand is introduced into the kneading tank 3, normal temperature air is directly injected into the sand to cause the sand to flow, and the sand is used as shot blast to cause the inner surface of the kneading tank and the stirring blade 4 If the sand or resin adhering to the kneading roller 5 is removed, the sand or resin adhering to the inner surface of the kneading tank or the stirring blade 4 is peeled off, and defective casting sand mixed in the sand being processed is produced. Can be prevented.

  Reference numeral 40 denotes a thermocouple as temperature detecting means, and the thermocouple 40 is attached to the body wall and bottom of the kneading tank 3. The kneading tank temperature and the sand temperature are monitored via a thermocouple 40 as a temperature detecting means, and the injection flow rate of normal air, cold air, hot air, etc. injected from the injection device 30 is set, or the sand temperatures st1, st2, Based on st3 and load current values such as peak load current i1 and reduced load current i2 of kneading motor 6 described above or kneading tank humidity ht1, the feed time of raw material sand, the feed time of hexa water, the feed time of stekal and The discharge time of the foundry sand is controlled. Decreasing load current i2 is obtained by supplying sand as a lubricant to the sand and kneading and kneading to disperse the sand and increase the fluidity. Is obtained.

  In such a configuration, first, the kneading tank temperature is detected by the temperature detecting means, and the kneading tank 3 is cooled or heated by using the cooling means or the injection device 30 so as to be the kneading tank temperature t1. When the kneading tank 3 reaches the kneading tank temperature t <b> 1, pre-heated raw material sand is charged from the charging port 1 a of the kneading tank 3. At this time, the amount of sand introduced from the introduction port 1a is set so that the mounting bracket 16 of the kneading roller 5 is not immersed. Since the sand is preheated in advance, the air is cooled to a predetermined sand temperature st1 while the molding sand is agitated and flowed by direct injection of normal temperature air or cold air from the cooling means of the kneading tank 3 or the nozzles 30a and 30c of the injection device 30.

  When the sand temperature st1 is detected by the temperature detecting means, a predetermined amount of resin is supplied from the resin supply port 7. The resin and sand supplied into the kneading tank 3 are agitated by the agitating blade 4 composed of the inner blade 4a and the scraping blade 4b rotated by the agitating motor 6. The resin melted by the kneading roller 5 rotated by the stirring motor 6 is pressed against the sand and attached.

  During this resin kneading, the cooling means of the kneading tank 3 and the injection device 30 are operated based on the sand temperature detected by the thermocouple 40 as temperature detecting means so that the sand temperature st1 is maintained. When normal temperature air, cold air, hot air, or these are injected into the sand by the nozzles 30a and 30c of the injection device 30, the sand is stirred and fluidized, so that the normal temperature air, cold air, hot air, etc. come into contact with the sand particles and the sand temperature is increased. The temperature can be rapidly shifted to a predetermined temperature.

  Further, during the kneading process, the mounting bracket 16 can reduce the load on the agitating motor 6 that is not immersed in the raw material sand, so that power is saved, and it can be used for a long time without being worn by the sand. Moreover, since the kneading roller 5 is attached by a mounting bracket 16 made of a spring material, the kneading roller 5 does not crush the sand even when it rides on the solidified sand adhered to the thin metal plate 3a for lining, etc. Since the kneading roller 5 escapes by the mounting bracket 16 made of a material, an excessive load is not applied to the stirring motor 6. For this reason, the load current value detected by the load current detecting means does not fluctuate greatly to show a load current value greatly different from the actual sand viscosity.

  By kneading the sand in this manner, the resin is deposited on the sand and the load applied to the stirring motor 6 increases. Then, the resin is applied to the sand particles, the viscosity of the sand becomes maximum, and the peak load current i1 flowing through the agitating motor 6 is detected by the load current detecting means.

  When the completion of the resin deposition is detected in this manner, hexa water is jetted and supplied into the sand from the nozzle 30a serving as a hexa water supply port to cool and cure the resin. At this time, the cooling time can be shortened by accelerating the cooling of the sand on which the resin is deposited by injecting normal temperature air or cold air from the other nozzles 30a and 30c of the injection device 30. Moreover, when the temperature of sand falls too much by injection of hexa water, a hot air is injected a little from the injection apparatus 30. FIG.

  In this manner, the resin is cooled and hardened, and the sand temperature st3 is detected by the thermocouple 40 of the temperature detection means, and is measured from the steer supply port 8 based on the kneading tank humidity ht1 detected by the humidity detection means. Calcium stearate (stecar) as a lubricant is supplied.

  By introducing the stekal into the resin-coated sand, the lump sand is dispersed by the resin and free fluidity is imparted, so the load current of the agitating motor 6 decreases rapidly. When the load current detecting means detects the reduced load current i2 and the sand temperature st3 is detected, the processing by the steal is completed, so the discharge port 1b of the kneading tank 3 is opened and the foundry sand is discharged. Discharge from 1b.

It is a front view which shows preferable embodiment of this invention. It is a side view similarly. It is also a plan view. It is a cross-sectional view similarly. It is a graph which shows the load current of the motor for stirring.

Explanation of symbols

1a inlet
1b Discharge port 3 Kneading tank 4 Agitation blade 5 Kneading roller 6 Agitation motor 7 Resin supply port 8 Steal supply port
16 Mounting bracket made of spring material
30 Injection device
30a Nozzle as hexa water supply port

Claims (5)

  Based on the kneading tank temperature t1 detected by the temperature detecting means provided in the temperature-adjustable cylindrical kneading tank, the raw material sand is put into the kneading tank, and the sand temperature st1 detected by the temperature detecting means. The resin is supplied into the sand based on the pressure, the hexagonal water is supplied based on the peak load current i1 of the stirring motor detected by the load current detecting means, and the sand temperature st2 detected by the temperature detecting means. The kneading process is completed based on the reduced load current i2 detected by the load current detecting means and the sand temperature st3 detected by the temperature detecting means, and the foundry sand is discharged. A method for producing foundry sand.   2. The foundry sand manufacturing method according to claim 1, wherein the steal supply is based on the sand temperature st2 and the kneading tank humidity ht1.   A stirring blade and a kneading roller arranged in the tank are placed on the top plate of a cylindrical kneading tank provided with a raw material sand inlet, a resin supply port, a steak supply port, a hexa water supply port, and a casting sand discharge port. A driving agitating motor is installed, and the sand kneading tank temperature t1 for determining the sand charging time, the sand temperatures st1 and st2 for determining the resin and steal supply timing, and the kneading treatment are completed, and the discharge of the foundry sand is determined. Temperature detecting means for detecting the sand temperature st3 which is one of the conditions, the peak load current i1 of the stirring motor for determining the supply timing of the hexa water and the sand for determining the discharge of the foundry sand after completing the kneading process A foundry sand manufacturing apparatus, comprising: a load current detecting means of a stirring motor for detecting a reduced load current i2 applied to a temperature st3 condition.   3. The foundry sand production apparatus according to claim 2, wherein the kneading tank is provided with humidity detecting means for detecting the kneading tank humidity ht1. The kneading roller is attached to the agitating motor via a mounting bracket made of a spring material disposed at a position higher than the supply level of the raw material sand to be put into the kneading tank. The casting sand manufacturing apparatus as described.

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