Cooling system

Abstract

[Problem] To reduce the frequency of nozzle clogging and to reduce defects caused by sticking. [Solution] The present invention relates to a cooling system 1 provided in a core making machine M comprising a core mold 60 having a cavity inside for molding a core m, and a blow nozzle 40 for supplying a kneaded sand mixture d obtained by mixing an inorganic binder b with casting sand s to the inside of the cavity of the core mold, the cooling system 1 being for cooling the blow nozzle. The cooling system 1 comprises a cooling device 120 for cooling the blow nozzle, a thermohygrometer 90 installed in the vicinity of the core making machine, a control device 130 for controlling the cooling device, and a calculation / communication device 110 for calculating a dew point temperature TDP after acquiring information on temperature and humidity from the thermohygrometer, computing a temperature rise occurring partway along the cooling path, and computing a temperature by correcting the dew point temperature using the temperature rise. The control device controls the cooling device on the basis of the corrected temperature computed by the calculation / communication device.

Description

Cooling system

[0001] The present invention relates to a cooling system.

[0002] Numerous casting techniques have been known for some time. In the production of molds such as cores, an inorganic binder, primarily composed of a water-soluble inorganic compound, is mixed with foundry sand, and the resulting mixed sand is then filled into a mold and fired to produce the inorganic core.

[0003] JP 2009-241135 A

[0004] The inventors have focused on the following problem with the above-described mold formation. Specifically, mixed sand is filled into the cavity space inside the mold through a nozzle, but if the nozzle is not cooled sufficiently, the mixed sand at the nozzle tip solidifies, potentially causing the nozzle to clog. On the other hand, if the nozzle is cooled too strongly, moisture in the air condenses on the outer wall of the nozzle, increasing the moisture content of the mixed sand at the nozzle tip, causing the sand to stick to the mold directly below the nozzle. This can result in a "staining defect" in which the core shape is torn off during demolding.

[0005] An object of the present invention is to reduce the frequency of nozzle clogging and to suppress the adhesion of sand to the mold.

[0006] One aspect of the present invention is a cooling system for cooling a blow nozzle in a core molding machine having a core mold with an internal cavity space for molding a core, and a blow nozzle that supplies mixed sand, which is a mixture of inorganic binder and molding sand, into the cavity space of the core mold. The cooling system includes a cooling device, a thermo-hygrometer, a control device, and a computing device. The cooling device cools the blow nozzle. The thermo-hygrometer is installed near the core molding machine. The control device is configured to control the cooling device. The computing device calculates a dew point temperature after obtaining air temperature and humidity information from the thermo-hygrometer, calculates a temperature rise midway through the cooling path, and calculates a temperature obtained by correcting the dew point temperature by the temperature rise.

[0007] The cooling system described above can reduce the frequency of nozzle clogging and prevent sand from sticking to the mold.

[0008] 1 is a schematic diagram showing a cooling system according to an embodiment; FIG. 2 is a simplified diagram of the cooling system of FIG. 1; FIG. 3 is a schematic diagram showing a blow head and a blow nozzle that constitute the cooling system; FIG. 4 is a schematic diagram showing a cooling circuit of a blow nozzle that constitutes the cooling system; FIG. 5 is a schematic diagram showing water mixing into mixed sand at the tip of a blow nozzle due to condensation; FIG. 6 is a schematic diagram showing nozzle clogging of a blow nozzle; FIG. 7 is a schematic diagram showing the mechanism by which sand sticking to a core mold occurs; FIG. 8 is a schematic diagram showing the mechanism by which poor core adhesion occurs; FIG. 9 is a graph showing the relationship between air temperature, humidity, and dew point temperature around a molding machine; FIG. 10 is a flowchart for setting the cooling water temperature of the cooling circuit of a blow nozzle; FIG. 11 is a schematic diagram showing a core molding process; and FIG. 12 is a graph showing the transition of the set temperature of a cooling device in an experiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted. In the drawings, the size and proportions of each component are exaggerated to facilitate understanding of the embodiments, and may differ from the actual size and proportions.

[0010] Fig. 1 is a schematic diagram showing a cooling system 1 according to an embodiment. Fig. 2 is a simplified diagram of the cooling system 1 shown in Fig. 1. Fig. 3 is a schematic diagram showing a blow head 30 and a blow nozzle 40 that constitute the cooling system 1.

[0011] 1 and 2 , the cooling system 1 in this embodiment includes a kneading kettle 10, a chute 20, a blow head 30, a blow nozzle 40, a molding plate 50, a core mold 60, an unloader 70, a robot 80, and a thermo-hygrometer 90. The cooling system 1 also includes a calculation and communication device 110 (corresponding to a calculation device and a communication means), a cooling device 120, and a control device 130. The cooling system 1 cools the blow nozzle 40 in a core molding machine M, which includes the core mold 60 having a cavity space therein for molding a core m, and the blow nozzle 40 for supplying mixed sand d, which is a mixture of an inorganic binder b and foundry sand s, into the cavity space of the core mold 60. This will be described in detail below.

[0012] (Mixing kettle) The mixing kettle 10 is configured as a portion where the materials for the core m are mixed. A stirring rod or the like can be operably accommodated inside the mixing kettle 10. Foundry sand s, a liquid inorganic binder b such as water glass, and the like can be charged into the mixing kettle.

[0013] (Chute) The chute 20 is configured to form a passage for moving the mixed sand to the blow head 30. The chute 20 is formed in a generally downward frustum shape and is positioned so as to transport the mixed sand d delivered from the mixing tank 10 to the blow head 30.

[0014] (Blow Head) The blow head 30 forms an internal space 31 for accommodating the mixed sand d, and is arranged so that a blow nozzle 40 is attached to its tip. The blow head 30 is arranged on the side where the chute 20 is provided, and is equipped with a base portion provided with a cooling circuit 32, and a tip portion that is connected to the base in the vertical direction and has a wider width than the base portion. The cooling circuit 32 of the blow head 30 is provided so that when the temperature of the blow head 30 rises, the moisture in the mixed sand d will evaporate and the mixed sand d will not solidify.

[0015] (Blow Nozzle) The blow nozzle 40 is disposed at the tip of the blow head 30. The blow nozzle 40 is configured to fill the cavity space of the core mold 60 with mixed sand d, which is a mixture of inorganic binder b and foundry sand s. In this embodiment, the blow nozzle 40, together with the fixed mold 62 and the movable mold 61, forms the closed space of the core mold 60. To accelerate hardening of the mixed sand d filled in the core mold, the blow nozzle 40 has a function of purging heated air from the molding plate 50 into the cavity space of the core mold 60 and an electric heater installed within the core mold 60. In FIGS. 1 to 4, four blow nozzles 40 are illustrated as being installed at the tip of the blow head 30; however, the number and installation positions of the blow nozzles 40 are not limited to those illustrated, as long as the desired shape can be formed with a good yield.

[0016] 4 is a schematic diagram showing the cooling circuit 42 of the blow nozzle 40. A blow tip 41 can be provided at the tip of the blow nozzle 40. Inside the blow nozzle 40, there is provided a space for circulating cooling water from the cooling device 120, and a cooling circuit 42 for discharging cooling water to the cooling device 120. The cooling circuit 32 of the blow head 30 and the cooling circuit 42 of the blow nozzle 40 can be configured to communicate with each other.

[0017] 5 is a diagram showing condensation on the blow nozzle 40. When condensation occurs on the blow nozzle 40, water droplets mt drip from the blow nozzle 40 and may get mixed into the mixed sand d discharged from the tip of the blow nozzle 40.

[0018] 6 is a diagram showing nozzle clogging of the blow nozzle 40. The temperature of the tip of the blow nozzle 40 rises due to heat input from the mold when the mixed sand d is filled, so if the blow nozzle 40 is not cooled enough, the mixed sand d may solidify at the tip of the blow nozzle 40, causing blockage and nozzle clogging (see portion pr1). Therefore, in this embodiment, in order to suppress condensation on the blow nozzle 40 and prevent nozzle clogging, the cooling water temperature setting of the cooling circuit 42 installed in the blow nozzle 40 is appropriately adjusted by the cooling device 120.

[0019] (Molding Plate) The molding plate 50 is configured to be movable toward and away from the core mold 60 in one direction, such as the height direction (vertical direction), so as to apply pressure to the core mold 60. The molding plate 50 is provided with a plurality of molding pins 51 at the tip on the core side in the moving direction. As a result, when the molding plate 50 moves, the molding pins 51 adjust the shape of the mixed sand d filled in the core mold 60, so that the finished core does not or is less likely to have unevenness.

[0020] (Core Mold) Figures 7 and 8 are diagrams illustrating the mechanisms of sand adhesion to the core mold 60 and the occurrence of defects due to the staining of the core m. The core mold 60 is configured to form a molding space inside for forming the core m and includes a pair of molds: a movable mold 61 such as an upper mold and a fixed mold 62 such as a lower mold. Regarding sand adhesion to the mold (described later), when the mixed sand d is filled into the core mold 60, the mixed sand d is slammed against the fixed mold 62, causing the inorganic binder b, which contains a large amount of water, to easily adhere to the fixed mold 62. Furthermore, accumulation 63 formed by the inorganic binder b adhering to the fixed mold 62 may cause the core m to be underfilled during demolding. Regarding this issue, as described above, the occurrence of such a phenomenon is suppressed by adjusting the temperature of the cooling water supplied to the cooling circuit 42 provided in the blow nozzle 40.

[0021] (Unloader, Robot) The unloader 70 can be used to move the core m formed by the core mold 60 to a nearby table or the like. The robot 80 (hand) can be used to load the core moved by the unloader 70 onto an AGV or the like.

[0022] (Thermo-hygrometer) One thermo-hygrometer 90 is installed near the core molding machine M. The location for measuring temperature and humidity can be determined to be one location within the production line. In addition, a calculation and communication device 110, which will be described later, is installed alongside the thermo-hygrometer 90, so that a correction temperature can be calculated by the single calculation and communication device 110 based on the measurement results from one thermo-hygrometer 90, and the calculation results can be communicated to multiple control devices 130. This makes it possible to reduce the introduction cost of this system.

[0023] (Computing and Communication Device) The computing and communication device 110 includes a PLC, a display with a touch panel, and hardware necessary for communication, and is configured to be able to communicate with the control device 130, etc. The computing and communication device 110 acquires information on the temperature and humidity from the thermo-hygrometer 90 and calculates the dew point temperature T ＤＰ Calculate the temperature rise during the cooling path, and calculate the dew point temperature T ＤＰThe calculation and communication device 110 then communicates with the control device 130 at regular intervals to control the cooling device 120 at the corrected temperature.

[0024] When the mixed sand d is filled, the mixed sand d is slammed against a mold such as the core mold 60, and the inorganic binder b, which contains a large amount of water, tends to adhere to the mold.

[0025] If the blow nozzle 40 is cooled too strongly, moisture in the air will condense on the outer wall of the blow nozzle 40, increasing the moisture content of the mixed sand d at the nozzle tip (see Figure 5). This will cause the sand to stick to the mold directly below the nozzle, resulting in poor adhesion. In other words, the inorganic binder b will accumulate and adhere to the fixed mold 62, causing the core m to be underfilled (stripped off) when released from the mold. Furthermore, even if the cooling temperature for the blow nozzle 40 is set as low as possible within the temperature range where condensation does not occur, the conditions under which condensation will occur on the outer wall of the blow nozzle 40 will change depending on weather conditions.

[0026] In response to this, the computing device and communication device 110 controls the cooling device 120 to calculate the dew point temperature T ＤＰ By outputting a value corrected for the temperature rise along the cooling path, it becomes possible to actively cool the blow nozzle 40. This reduces the frequency of nozzle clogging and improves output. In addition, by eliminating condensation, sand adhesion to the mold is suppressed, reducing staining defects and contributing to improved quality.

[0027] (Cooling Device) The cooling device 120 is configured to cool the blow nozzle 40 and suppress a rise in temperature of the blow nozzle 40. The cooling device 120 is configured to cool the blow nozzle 40 by circulating cooling water in a chiller cooling device. The cooling device 120 can be configured to operate when the device is powered on.

[0028] (Controller) The controller 130 includes a PLC, a display with a touch panel, and hardware necessary for communication, and controls the operation of the molding machine M and the cooling device 120.

[0029] FIG. 9 shows the dew point temperature T calculated from the temperature and humidity using Equation 2 described later.ＤＰ In mixed sand d, which is a mixture of inorganic binder b and foundry sand s, the water in the sand evaporates when the temperature of the mixed sand d itself rises, shortening the time it takes to solidify.

[0030] Therefore, the water used to cool the blow nozzle 40 is also supplied to the cooling circuit 32 in the blow head 30 to cool the mixed sand d in the blow head 30. If the temperature of the mixed sand d in the blow head 30 exceeds a certain temperature, it may solidify during continuous operation, hindering the supply of sand to the blow nozzle 40 (see parts pr2 and pr3). In response to this, the inventors came up with the idea of ​​setting an upper limit on the temperature of the cooling water supplied to the cooling device 120, based on the relationship shown in Figure 9. By setting an upper limit on the temperature of the cooling water supplied to the cooling device 120 in this way, solidification of the mixed sand d in the blow head 30 can be suppressed, and the frequency of cleaning the solidified sand in the blow head 30 can be reduced.

[0031] Next, a method for manufacturing the core m according to this embodiment will be described. Fig. 10 is a flow chart showing the temperature setting of the cooling device 120 that cools the blow nozzle 40. Fig. 11 is a schematic diagram showing the molding process of the core m.

[0032] First, foundry sand s, inorganic binder b, etc. are loaded into the kneading tank 10. The loaded materials are mixed in the kneading tank 10 and transferred to the blow head 30 via the chute 20. Next, the core mold 60 is clamped, the blow nozzle 40 is pressed against the core mold 60, and mixed sand d is filled into the core mold 60 from the blow nozzle 40. The blow nozzle 40 is then retracted from the core mold 60. Next, the molding pins 51 of the molding plate 50 are pressed to shape the mixed sand d. The core m is heated (fired) by purging heated air into the core mold 60 and heating with an electric heater, and the moisture in the binder is vaporized (gassing). Once the core m is completed, the mold is opened, and the core m is transferred from the core mold 60 to the deburring table using the ejector pin p and unloader 70, where it is deburred. The deburred core m is then transferred to an AGV by a robot 80 and transported to another location.

[0033] In this process, the computing and communication device 110 acquires the temperature and humidity measured by the thermo-hygrometer 90 (S1). When the computing and communication device 110 acquires the temperature and humidity from the thermo-hygrometer 90, the computing and communication device 110 calculates the dew-point temperature T ＤＰ The set temperature T of the cooling circuit 42 of the blow nozzle 40 is calculated. ｃｈｉｌｌｅｒ (see Equation 1) is determined (S2). ｃｈｉｌｌｅｒ is a correction value T obtained empirically from the measured values ​​of one thermo-hygrometer 90 for each core molding machine M. ｏｆｆｓｅｔ The dew point temperature T ＤＰ The correction value T ｏｆｆｓｅｔ By adjusting the temperature for each core molding machine M, the set temperature T ｃｈｉｌｌｅｒ can be calculated for each core molding machine M (see Equation 1). ｃｈｉｌｌｅｒ is calculated with a lower limit and an upper limit set. The following formula can be stored as a program in the calculation and communication device 110.

[0034]

[0035]

[0036]

[0037] The correction value T in Equation 1 ｏｆｆｓｅｔ is the numerical value of the increase in cooling water temperature when the cooling water circulates in the cooling device 120 for each core molding machine M. In addition, in equation 2, A = 6.1078, B = 7.5, and C = 237.3, and RH is the atmospheric humidity around the core molding machine M. In addition, in equation 3, t is the atmospheric temperature around the core molding machine M.

[0038] The calculation and communication device 110 calculates the dew point temperature T ＤＰ A correction value T is added to take into account the temperature rise. ｏｆｆｓｅｔ The set temperature T ｃｈｉｌｌｅｒ Then, the computing and communication device 110 determines whether a predetermined time has elapsed since the start of temperature and humidity measurement (S3). If the predetermined time has not elapsed (S3: NO), the computing and communication device 110 calculates the temperature and humidity measurement and the dew-point temperature TＤＰ Calculation of the set temperature T ｃｈｉｌｌｅｒ If the predetermined time has elapsed (S3: YES), the calculation and communication device 110 communicates with the control device 130 and calculates the set temperature T ｃｈｉｌｌｅｒ (S4, S5). Then, for each core molding machine M, it is determined whether or not to continue the operations of S1 to S5 based on the state of the molding machine power supply (S6). If the power supply of the core molding machine M is ON (S6: ON), the processing continues, and if the power supply is OFF (S6: OFF), the processing ends. This processing prevents nozzle clogging of the blow nozzle 40 and prevents staining defects.

[0039] (Experiment) Next, an experiment on the cooling of the blow nozzle 40 was conducted, which will be described. In this experiment, clogging and staining defects of the blow nozzle 40 were confirmed under the following circumstances. In this experiment, an actual cooling system 1 was used to compare nozzle clogging and staining defects between a case where the set temperature of the blow nozzle 40 from midnight on a certain day to midnight 24 hours later was manually set by an operator and a case where the set temperature was set by the calculation and communication device 110. Figure 12 is a graph showing the transition of the set temperature of the blow nozzle 40 in the experiment.

[0040] Dew point temperature T ＤＰ The temperature remained almost constant from midnight to just after 4:00, but rose by nearly 5°C from around 5:00 to 8:00. The set temperature of the cooling device 120 was almost the same between the set by the operator and the set by the calculation and communication device 110 from midnight to around 5:00. However, when the temperature was set by the operator, the blow nozzle 40 frequently became clogged with mixed sand d at around 8:00, so the set temperature was raised with a delay of about 2 to 3 hours compared to the set by the calculation and communication device 110. After that, the dew point temperature T ＤＰ While the temperature was generally on a downward trend, the temperature set by the operator was set at a constant temperature from 8:00 to around 19:00, and since many problems with ink adhesion were observed after 19:00, the temperature was suddenly lowered. Conversely, the settings made by the calculation and communication device 110 did not result in the nozzle clogging and ink adhesion problems seen with the settings made by the operator.

[0041] It has been confirmed that by using the cooling system 1 including the calculation / communication device 110, the cooling device 120, and the control device 130 in this manner, nozzle clogging in the blow nozzle 40 can be suppressed and staining defects can also be suppressed.

[0042] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. The computing and communication device 110 may be separate from the control device 130 for controlling the cooling device 120 as described above, and the computing and communication device 110 may be configured to perform calculations within the control device for controlling the cooling device 120.

[0043] 30 Blow head, 32 Cooling circuit, 40 Blow nozzle, 42 Cooling circuit, 60 Core mold, 90 Thermo-hygrometer, 110 Calculation and communication device (calculation device, communication means), 120 Cooling device, 130 Control device, b Inorganic binder, d Mixed sand, M Core molding machine, s Foundry sand, T ＤＰ Dew point temperature, T ｏｆｆｓｅｔ Correction value, T ｃｈｉｌｌｅｒ Set temperature.

Claims

1. A cooling system for cooling the blow nozzle in a core molding machine having a core mold with a cavity space inside for molding a core, and a blow nozzle that supplies mixed sand, which is a mixture of inorganic binder and molding sand, into the cavity space of the core mold, comprising: a cooling device that cools the blow nozzle; a thermo-hygrometer installed near the core molding machine; a control device that controls the cooling device; and a computing device that calculates a dew point temperature after obtaining air temperature and humidity information from the thermo-hygrometer, calculates a temperature rise midway through the cooling path, and calculates a temperature obtained by correcting the dew point temperature by the temperature rise, wherein the control device controls the cooling device using the corrected temperature calculated by the computing device.

2. A cooling system as described in claim 1, wherein the blow nozzle is provided with a cooling circuit that supplies the blow head with water used to cool the blow nozzle, and the control device controls the temperature of the water supplied to the cooling circuit so that it does not exceed a predetermined value.

3. A cooling system as described in claim 1, wherein one thermo-hygrometer and one computing device are installed for each of the core molding machines, and the system has communication means for calculating the correction temperature using one computing device based on the measurement results from one thermo-hygrometer and transmitting the calculation results to the multiple control devices.

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