EP1832358B1 - Casting mold making method and casting mold making system - Google Patents
Casting mold making method and casting mold making system Download PDFInfo
- Publication number
- EP1832358B1 EP1832358B1 EP07004056A EP07004056A EP1832358B1 EP 1832358 B1 EP1832358 B1 EP 1832358B1 EP 07004056 A EP07004056 A EP 07004056A EP 07004056 A EP07004056 A EP 07004056A EP 1832358 B1 EP1832358 B1 EP 1832358B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- casting sand
- receiver
- casting
- sand
- stirring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
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- 238000005266 casting Methods 0.000 title claims description 219
- 238000000034 method Methods 0.000 title claims description 28
- 239000004576 sand Substances 0.000 claims description 199
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 80
- 238000003756 stirring Methods 0.000 claims description 79
- 239000002904 solvent Substances 0.000 claims description 65
- 238000007664 blowing Methods 0.000 claims description 40
- 238000012856 packing Methods 0.000 claims description 37
- 239000011230 binding agent Substances 0.000 claims description 21
- 238000000465 moulding Methods 0.000 claims description 16
- 238000001514 detection method Methods 0.000 claims description 10
- 239000007921 spray Substances 0.000 claims description 8
- 238000005507 spraying Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 description 14
- 238000004898 kneading Methods 0.000 description 10
- 239000011347 resin Substances 0.000 description 7
- 229920005989 resin Polymers 0.000 description 7
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000005011 phenolic resin Substances 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 239000005056 polyisocyanate Substances 0.000 description 3
- 229920001228 polyisocyanate Polymers 0.000 description 3
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 description 1
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- -1 alicyclic hydrocarbons Chemical class 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- MHDVGSVTJDSBDK-UHFFFAOYSA-N dibenzyl ether Chemical group C=1C=CC=CC=1COCC1=CC=CC=C1 MHDVGSVTJDSBDK-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 229920003986 novolac Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
- B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor
- B22C5/044—Devices having a vertical stirrer shaft in a fixed receptacle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C15/00—Moulding machines characterised by the compacting mechanism; Accessories therefor
- B22C15/23—Compacting by gas pressure or vacuum
- B22C15/24—Compacting by gas pressure or vacuum involving blowing devices in which the mould material is supplied in the form of loose particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
- B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor
- B22C5/044—Devices having a vertical stirrer shaft in a fixed receptacle
- B22C5/0445—Devices having a vertical stirrer shaft in a fixed receptacle the material flowing continuously through the device
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/12—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose for filling flasks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/12—Treating moulds or cores, e.g. drying, hardening
- B22C9/123—Gas-hardening
Definitions
- This invention relates to the technical field of a casting mold making method and system in which gas-curing casting sand is blown and packed into a cavity created by molding dies.
- gas-curing casting sand containing a binder (a phenol resin and a polyisocyanate compound) and a solvent (such as toluene) is previously accommodated in a blow head, the casting sand is blown and packed through the blow nozzles into a cavity in molding dies by feeding pressurized gas into the blow head and a curing gas (such as triethylamine gas) is then introduced into the cavity to cure the casting sand packed in the cavity, thereby making a casting mold.
- a binder a phenol resin and a polyisocyanate compound
- a solvent such as toluene
- casting sand in a blow head is suspended and fluidized by air, lumps of the casting sand are broken up by passing them through a cutter and the casting sand is then blown and packed into the cavity by pressurized air.
- Gas-curing casting sand as described above has a sticky particle surface owing to the binder. Therefore, the bulk density of gas-curing casting sand in the blow head greatly varies. This makes it difficult to ensure a constantly good packability of casting sand into the cavity.
- the solvent adhering to the surfaces of the sand particles together with the binder is blown off by the air to increase the concentration of the binder on the sand particle surface and thereby accelerate the curing reaction of the casting sand.
- the casting sand is cured prior to its packing into the cavity of the molding dies, thereby degrading the quality of a casting mold to be formed.
- the solvent coated on the sand particles is highly likely to be reduced.
- Document JP-A 58 196 145 discloses a mold forming method.
- a high-pressure gas for curing is supplied into a blow head.
- a valve is opened to supply the compressed air in a receiver tank into the head.
- the sand in the blow head is mixed wit the gas for curing and in this state, the sand is blown into split patterns.
- Document US 3 934 858 discloses a method of and apparatus for mixing foundry sand, resin binder and catalyst, wherein sand/resin and sand/catalyst mixtures are prepared separately in continuous mixers and conveyed to a final mixing chamber having a vertical high speed rotating shaft with downwardly inclined mixer blades and upwardly inclined deflector blades.
- Document US 3 994 332 discloses an apparatus and method for forming foundry cores and molds includes staging hoppers for storing a first mass of sand coated with a catalyst-polymerizable resin film, and a second mass of sand coated with a catalyst film for polymerizing the resin.
- these masses are evenly dispersed into a high velocity carrier air-sand stream and directed through a static mixer, wherein the resin and catalyst-coated sand particles are intermingled and at least a partial inttegration of the films takes place, into a shaping mold cavity, wherein the sand mixture hardens into a desired shape.
- Document JP A 55 001 961 discloses a casting-mold molding machine. Casting sand, binder and volatile flux dissolving said binder are supplied from a sand hopper, binder pump and a flux pump into a blow head, which is closed in a hermetic state by a plug member, where they are kneaded. Further a device which recovers the volatile gas of the flux evaporating from the kneaded sand into the molds is provided.
- the present invention has been made in view of the foregoing points and, therefore, advantageously, it is possible to blow and pack gas-curing casting sand into a cavity created by molding dies while ensuring good, constant packability without curing the casting sand prior to the packing into the cavity.
- casting sand in a blow head is stirred with a stirrer prior to its blowing and packing into the cavity until the stirring resistance of the stirrer enters within a predetermined range corresponding to an optimum bulk density range wherein the kinetic energy of the casting sand is maximised during blowing.
- a method for making a casting mold of the present invention comprises: a blowing and packing step of feeding pressurized gas into a receiver that is provided in a blow head and accommodates gas-curing casting sand, thereby blowing the casting sand in the receiver into a cavity in molding dies through a blow nozzle that is provided in the blow head and communicates with the receiver and packing the casting sand into the cavity; a curing step of, after the blowing and packing step, introducing curing gas into the cavity to cure the casting sand packed in the cavity; and a stirring step of, before the blowing and packing step, stirring the casting sand in the receiver with a stirrer until the stirring resistance of the stirrer enters within a predetermined range corresponding to an optimum bulk density range wherein the kinetic energy of the casting sand is maximised during blowing.
- the casting sand in the receiver is stirred and unstiffened. If the bulk density of casting sand thus stirred is too high, the casting sand clogs the blow nozzle and thereby becomes difficult to get out of the blow nozzle. On the contrary, if the casting sand is excessively unstiffened to reach an excessively small bulk density, only the pressurized gas quickly blows out through the blow nozzle and, also in this case, the casting sand becomes difficult to get out of the blow nozzle. In other words, there exists an optimum bulk density range within which casting sand can efficiently blow out through the blow nozzle.
- casting sand in the receiver is not stirred, its bulk density is generally higher than the optimum bulk density range.
- the bulk density of casting sand becomes higher and higher owing to pressures applied from pressurized gas.
- the stirring resistance of the stirrer is in correspondence with the bulk density of casting sand so that as the bulk density increases, the stirring resistance becomes higher.
- the stirring step, the blowing and packing step and the curing step are sequentially repeated and the predetermined range is set in each stirring step. More preferably, the predetermined range is set based on the amount of casting sand in the receiver in each stirring step.
- the predetermine range can be appropriately set based on the amount of casting sand in the receiver in each stirring step. Specifically, when the blowing and packing step is carried out once, the amount of casting sand in the receiver is reduced by the amount of casting sand packed into the cavity. If in this case no casting sand is supplementally fed into the receiver, the amount of casting sand in the receiver in the next stirring step differs from that in the previous stirring step. If the amount of casting sand changes thus, the relation between the bulk density of casting sand and the stirring resistance of the stirrer also changes. However, since in the present invention the range of stirring resistances corresponding to the optimum bulk density range can be set to the predetermined range, this provides good, constant packability in every stirring step.
- the casting sand contains a binder and a solvent and the method further comprises a solvent feed step of, before or during the stirring step, supplementally feeding the solvent into the receiver.
- the solvent coated on the sand particles can be prevented from being reduced.
- pressurized air is fed into the receiver in order to blow and pack casting sand into the cavity, whereby the solvent on the sand particles is blown away and reduced to a certain extent by the pressurized gas.
- the amount of solvent reduced can be supplementally fed, this prevents the quality of a produced casting mold from being degraded. Even if the solvent is supplementally fed thus, the binder, the solvent and sand can be stirred uniformly by stirring in the stirring step, which avoids that the solvent becomes locally excessive in the receiver.
- a casting mold making system of the present invention includes a blow head having a receiver for accommodating gas-curing casting sand and a blow nozzle communicating with the receiver and a pressurized gas feed system for feeding pressurized gas into the receiver of the blow head and is configured to feed pressurized gas into the receiver through the pressurized gas feed system and thereby blow the casting sand in the receiver through the blow nozzle into the cavity and pack the casting sand into the cavity.
- the casting mold making system further comprises: a stirrer for stirring the casting sand in the receiver; a stirrer drive unit for driving the stirrer; a stirring resistance detection device for detecting the stirring resistance of the stirrer; and an operation controller for controlling the operation of the stirrer drive unit, the operation controller being configured to, prior to the feeding of pressurized gas into the receiver through the pressurized gas feed system, operate the stirrer drive unit until the stirring resistance detected by the stirring resistance detection device enters within a predetermined range.
- the above casting mold making system further comprises a casting sand amount detection device for detecting the amount of casting sand in the receiver, wherein the operation controller is configured to set the predetermined range based on the amount of casting sand detected by the casting sand amount detection device.
- the casting sand contains a binder and a solvent
- the casting mold making system further comprises a solvent spray device for supplementally feeding, under the control of the operation controller, the solvent into the receiver by spraying, and the operation controller is configured to, before or during the operation of the stirrer drive unit, operate the solvent spray device to supplementally feed the solvent into the receiver.
- the above casting mold making method can be easily implemented and the same operations and effects as according to the above casting mold making method can be obtained.
- FIG. 1 schematically shows a casting mold making system according to an embodiment of the present invention.
- the casting mold making system is a cold box casting mold making system including a blow head 1 with a receiver 2 for accommodating gas-curing casting sand 41 .
- the casting sand 41 contains a binder composed of a phenol resin and a polyisocyanate compound and a solvent so that the surfaces of sand particles are coated with the binder and the solvent.
- the phenol resin in the binder include phenol resins having at least one benzyl ether group in its molecule, novolak resins and their derivative resins.
- the polyisocyanate compound examples include diphenylmethane diisocyanate, hexamethylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate.
- the solvent is an organic solvent including aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ketones, esters, ethers and alcohols, or their mixtures.
- the casting sand 41 is fed from a kneading unit 3 disposed above the receiver 2 to the receiver 2 .
- the binder, the solvent and sand are charged into the kneading unit 3 and uniformly kneaded by a kneader 4 driven into rotation in the kneading unit 3 , thereby providing casting sand 41 in which sand particles are coated with the binder and the solvent as described above.
- a shutter 5 opened and closed by a shutter drive mechanism 6 , is disposed between the receiver 2 and the kneading unit 3 .
- the operation of the shutter drive mechanism 6 is controlled by a controller 31 .
- the shutter 5 is opened by the shutter drive mechanism 6
- the casting sand 41 falls down from the kneading unit 3 by its own weight and is fed to the receiver 2 .
- the bottom of the blow head 1 is provided with a plurality of blow nozzles 9 , communicated with the receiver 2 , for blowing out casting sand 41 in the receiver 2 therethrough.
- the blow nozzles 9 are presented to a cavity 36 created by a plurality of molding dies 35 set up below the casting mold making system. Casting sand 41 blown out through the blow nozzles 9 is packed into the cavity 36 to have a shape of a casting mold to be made by the casting mold making system.
- Casting molds made by the casting mold making system include casting molds for cylinder blocks or cylinder heads and cores for water jackets of the cylinder heads.
- An upper portion of any one of the side walls defining the receiver 2 in the blow head 1 is formed with an air feed port 1a through which pressurized air serving as pressurized gas is fed into the receiver 2.
- the air feed port 1a is connected to an air tank 12 through a solenoid valve 11 whose actuation is controlled by the controller 31 .
- the air tank 12 is supplied with air in the factory while the air to the air tank 12 is kept at a constant pressure (about 0.2 MPa to about 1 MPa) by a regulator (not shown). The air supplied is stored as the pressurized air in the air tank 12 .
- the solenoid valve 11 When the solenoid valve 11 is actuated, the pressurized air in the air tank 12 is fed into the receiver 2 , whereby casting sand 41 in the receiver 2 is blown through the blow nozzles 9 into the cavity 36 in the molding dies 35 and packed into the cavity 36 .
- the solenoid valve 11 , the air tank 12 and the controller 31 constitute pressurized gas feed system for feeding pressurized gas into the receiver 2 .
- the pressurized air, blown into the cavity 36 together with the casting sand 41 is vented out of the cavity 36 through air vents 37 attached to the bottom of the molding die 35 .
- An upper portion of any one of the side walls defining the receiver 2 is formed with a solvent feed port 1b through which the solvent is supplementally fed into the receiver 2.
- the solvent feed port 1b is connected to a solvent spray device 15 for supplementally feeding the solvent into the receiver 2 by spraying it.
- the operation of the solvent spray device 15 is controlled by the controller 31 and operates prior to the actuation of a drive motor 22a of the after-mentioned stirrer drive unit 22 to supplementally feed a given amount of solvent into the receiver 2 by spraying.
- the solvent on the sand particles has been blown away and reduced to a certain extent by pressurized air. Therefore, the solvent is supplementally fed into the receiver 2 by substantially the same amount as the amount of solvent reduced.
- a casting sand amount sensor 16 serving as a casting sand amount detection device for detecting the amount of casting sand 41 in the receiver 2 .
- the casting sand amount sensor 16 is configured to emit infrared rays downward, receive infrared rays reflected from the top surface of the casting sand 41 and detect the amount of casting sand 41 in the receiver 2 based on the intensity of the reflected infrared rays.
- any appropriate sensors having other configurations can also be employed. Data on the amount of casting sand 41 in the receiver 2 detected by the casting sand amount sensor 16 is input to the controller 31 .
- a lower part of the interior of the receiver 2 of the blow head 1 is provided with a stirrer 21 for stirring casting sand 41 in the receiver 2 .
- the stirrer 21 is an element for unstiffening casting sand 41 to bring it to an optimum bulk density as described later.
- the stirrer 21 is composed of a rotary shaft 21a vertically extending and rotatably supported, a base plate 21b fixed to the lower end of the rotary shaft 21a and extending horizontally, and a plurality of stirring bars 21c disposed on the base plate 21b .
- the upper end of the rotary shaft 21a is connected to the stirrer drive unit 22 .
- the stirrer drive unit 22 includes a drive motor 22a , a connecting member made, for example, of flexible wire and connecting the rotary shaft of the drive motor 22a to the rotary shaft 21a , and a drive circuit for driving the drive motor 22a .
- the drive circuit includes a current detecting element 22b for detecting the value of current flowing into the drive motor 22a .
- the operation of the drive motor 22a of the stirrer drive unit 22 is controlled by the controller 31 .
- the controller 31 constitutes an operation controller for controlling the operation of the drive motor 22a of the stirrer drive unit 22 .
- data on the value of current detected by the current detecting element 22b is input to the controller 31 .
- the controller 31 is configured to, prior to the blowing and packing of casting sand 41 in the receiver 2 into the cavity 36 , operate the drive motor 22a until the stirring resistance of the stirrer 21 enters within a predetermined range.
- the stirring resistance of the stirrer 21 is detected by the current detecting element 22b .
- the value of current of the drive motor 22a is in correspondence with the motor torque required to rotate the stirrer 21 , i.e., the stirring resistance of the stirrer 21 , so that as the stirring resistance of the stirrer 21 increases, the value of current of the drive motor 22a increases.
- the current detecting element 22b constitutes a stirring resistance detection device for detecting the stirring resistance of the stirrer 21 .
- the predetermined range of stirring resistances i.e., the predetermined range of current values, is set at a range within which casting sand 41 in the receiver 2 can efficiently blow out through the blow nozzles 9 .
- the relation between the bulk density of casting sand 41 in the receiver 2 and the kinetic energy thereof blown out through the blow nozzles 9 was examined by changing the bulk density of casting sand 41 in the receiver 2 while keeping the amount thereof constant. The kinetic energy was determined from the mass of the casting sand 41 in the receiver 2 and the velocity of it blown out through the blow nozzles 9 . The examination results are shown in Figure 2 .
- Figure 2 indicates that there exists a bulk density range within which the kinetic energy reaches the maximum value or near the maximum value, in other words, an optimum bulk density range within which casting sand 41 efficiently blows out through the blow nozzles 9 .
- the reason for this is as follows. If the bulk density of casting sand 41 is excessively high, casting sand 41 clogs the blow nozzles 9 and thereby becomes difficult to get out of the blow nozzles 9 . On the other hand, if casting sand 41 is excessively unstiffened to reach an excessive low bulk density, only pressurized air quickly blows out through the blow nozzles 9 and, also in this case, casting sand 41 becomes difficult to get out of the blow nozzles 9 .
- Figure 3 indicates that the stirring resistance of the stirrer 21 is in correspondence with the bulk density of casting sand 41 so that as the bulk density increases, the stirring resistance also increases. Therefore, the blowing of casting sand 41 into the cavity 36 will do well if a range of stirring resistances corresponding to the optimum bulk density range is set at the above-described predetermined range of stirring resistances.
- a range of current values corresponding to the predetermined range of stirring resistance can be set at the above-described predetermined range of current values.
- the optimum bulk density range varies depending upon the amount of casting sand 41 in the receiver 2 . Therefore, the amount of casting sand 41 in the receiver 2 is detected by the casting sand amount sensor 16 . Specifically, an examination is previously made of the relation between the amount of casting sand 41 and the optimum bulk density range (i.e., the predetermined range of current values), the examination results are mapped in a table and the table is stored in the controller 31 . When receiving data on the amount of casting sand 41 from the casting sand amount sensor 16 during operation of the casting mold making system, the controller 31 sets, based on the table, a predetermined range of current values corresponding to the detected amount of casting sand 41 .
- the controller 31 actuates the shutter drive mechanism 6 to feed casting sand 41 from the kneading unit 3 into the receiver 2 .
- the solvent spray device 15 is operated to supplementally feed the given amount of solvent into the receiver 2 by spraying it.
- a predetermined range of current values is set. Specifically, the predetermined range of current values is set based on the amount of casting sand 41 in the receiver 2 detected by the casting sand amount sensor 16 and the table.
- step S3 the drive motor 22a of the stirrer drive unit 22 is operated in step S3 and it is then determined in step S4 whether the value of current detected by the current detecting element 22b is within the predetermined range of current values.
- step S4 If the determination in step S4 is NO, the procedure goes back to step S3. If the determination in step S4 is YES, the procedure goes to step S5 to stop the drive motor 22a and then goes to step S6 to actuate the solenoid valve 11 and thereby feed pressurized air in the air tank 12 into the receiver 2 .
- step S7 it is determined whether the amount of casting sand 41 detected by the casting sand amount sensor 16 is smaller than the predetermined amount. In the determination in step S7 is NO, the procedure ends. If the determination in step S7 is YES, the procedure goes to step S8 to actuate the shutter drive mechanism 6 and then ends.
- the molding dies 35 are set up in the casting mold making system and the casting mold making system is activated by switch operation or in other manners.
- the given amount of solvent is supplementally fed into the receiver 2 (a solvent feed step).
- the base plate 21b of the stirrer 21 rotates about the rotary shaft 21a , whereby the plurality of stirring bars 21c on the base plate 21b stir the casting sand 41 in the receiver 2 to unstiffen it (a stirring step).
- the binder, the solvent (including supplementally fed solvent) and sand in the receiver 2 are uniformly mixed.
- the bulk density of casting sand 41 in the receiver 2 is usually higher than the optimum bulk density range.
- the bulk density gradually decreases and then reaches the optimum bulk density range.
- the value of current detected by the current detecting element 22b enters within the predetermined range of current values and the operation of the stirrer 21 is stopped.
- the molding dies 35 are moved to an unshown curing gas introduction device disposed separately from the blow head 1 in order to introduce curing gas into the cavity 36 in the molding dies 35 , and placed in the curing gas introduction device. Then, curing gas (such as triethylamine gas) is introduced into the cavity 36 to cure the casting sand 41 packed in the cavity 36 (a curing step), thereby completing the making of a high-quality casting mold.
- curing gas such as triethylamine gas
- the molding dies 35 may be set up again in the casting mold making system in order to make another casting mold.
- the solvent feed step, the stirring step and the blowing and packing step are similarly sequentially carried out.
- the solvent on the sand particles however, has been blown away and reduced to a certain extent by pressurized air in the previous blowing and packing step. Therefore, in this solvent feed step, the solvent is supplementally fed by substantially the same amount as the amount of solvent reduced.
- the binder, the solvent (including supplementally fed solvent) and sand in the receiver 2 are further uniformly mixed. Furthermore, the amount of casting sand 41 generally becomes smaller than that in the previous stirring step (but becomes larger when casting sand 41 is fed from the kneading unit 3 into the receiver 2 ). Therefore, in such cases, the optimum bulk density range (the predetermined range of current values) corresponding to the amount of casting sand 41 is set again. In this manner, in each stirring step, the optimum bulk density range (the predetermined range of current values) is set based on the amount of casting sand 41 in the receiver 2 .
- the bulk density of casting sand 41 in the receiver 2 at the beginning of the stirring step is higher than the optimum bulk density range owing to the pressure applied from pressurized air in the previous blowing and packing step but the bulk density thereof at the end of the stirring step enters within the optimum bulk density range corresponding to the amount of casting sand 41 .
- the casting sand 41 can be well packed into the cavity 36 .
- the curing step is carried out. If the above steps are repeated in this manner, a large number of casting molds can be made.
- the shutter drive mechanism 6 is actuated to put the shutter 5 to an open position, whereby casting sand 41 is fed from the kneading unit 3 into the receiver 2 .
- casting sand 41 is stirred by the stirrer 21 prior to the blowing and packing of casting sand 41 into the cavity 36 , whereby the bulk density of casting sand 41 enters within the optimum bulk density range within which casting sand 41 can efficiently blow out through the blow nozzles 9 . Therefore, casting sand 41 can be constantly well packed into the cavity 36 .
- the solvent on the sand particles is not reduced in the stirring step.
- the solvent on the sand particles is reduced to a certain extent in the previous blowing and packing step, the amount of solvent thus reduced is supplementally fed by operating the solvent spray device 15 . This prevents the quality of a produced casting mold from being degraded.
- the stirring resistance of the stirrer 21 is detected by the current detecting element 22b for detecting the value of current flowing into the drive motor 22a of the stirrer drive unit 22
- the manner of detecting the stirring resistance of the stirrer 21 is not limited to this.
- the stirrer 21 may be provided with a torque sensor and its stirring resistance may be detected by the torque sensor.
- the casting sand amount sensor 16 may not be used, for example, in the case of making a large number of casting molds of the same configuration. Specifically, in this case, the amount of casting sand 41 reduced in a single blowing and packing step is substantially constant.
- the solvent is supplementally fed into the receiver 2 prior to the stirring step
- the solvent may be supplementally fed during the stirring step.
- the solvent may not be fed or the amount of solvent fed may be small.
- the solvent feed step antecedent to each stirring step may not be eliminated. This should not be a serious problem because the amount of solvent reduced in each blowing and packing step is very small.
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- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Casting Devices For Molds (AREA)
Description
- This invention relates to the technical field of a casting mold making method and system in which gas-curing casting sand is blown and packed into a cavity created by molding dies.
- In a well-known casting mold making method, such as disclosed in Published
Japanese Patent Application No. H03-47647 - In another known casting mold making method, such as disclosed in Published
Japanese Patent Application No. 2001-225148 - Gas-curing casting sand as described above has a sticky particle surface owing to the binder. Therefore, the bulk density of gas-curing casting sand in the blow head greatly varies. This makes it difficult to ensure a constantly good packability of casting sand into the cavity.
- To cope with this, it can be considered, as disclosed in the above Published
Japanese Patent Application No. 2001-225148 - However, if the latter method is applied to gas-curing casting sand, the following problems may occur. When air is blown to casting sand in order to suspend and fluidize it, the solvent adhering to the surfaces of the sand particles together with the binder is blown off by the air to increase the concentration of the binder on the sand particle surface and thereby accelerate the curing reaction of the casting sand. Thus, the casting sand is cured prior to its packing into the cavity of the molding dies, thereby degrading the quality of a casting mold to be formed. Furthermore, when lumps of the casting sand are passed through the cutter in order to break them up, the solvent coated on the sand particles is highly likely to be reduced.
- Document
JP-A 58 196 145 - Document
US 3 934 858 discloses a method of and apparatus for mixing foundry sand, resin binder and catalyst, wherein sand/resin and sand/catalyst mixtures are prepared separately in continuous mixers and conveyed to a final mixing chamber having a vertical high speed rotating shaft with downwardly inclined mixer blades and upwardly inclined deflector blades. - Document
US 3 994 332 discloses an apparatus and method for forming foundry cores and molds includes staging hoppers for storing a first mass of sand coated with a catalyst-polymerizable resin film, and a second mass of sand coated with a catalyst film for polymerizing the resin. In forming the cores or molds these masses are evenly dispersed into a high velocity carrier air-sand stream and directed through a static mixer, wherein the resin and catalyst-coated sand particles are intermingled and at least a partial inttegration of the films takes place, into a shaping mold cavity, wherein the sand mixture hardens into a desired shape. - Document
JP A 55 001 961 - Document
US 4 570 694 discloses a mold-blowing apparatus. A freshly mixed quick-setting sand mix is blown from a blow box into a mold while a plunger moves through the blow box to chase all of the fluidized sand into the mold. - Thus, according to an aspect, it is a problem to provide a method and apparatus for more efficiently making casting molds.
- This problem is solved by a method for making a casting mold having the features disclosed in
claim 1 and a casting mold making system disclosed inclaim 5. Preferred embodiments are defined in the dependent subclaims. - The present invention has been made in view of the foregoing points and, therefore, advantageously, it is possible to blow and pack gas-curing casting sand into a cavity created by molding dies while ensuring good, constant packability without curing the casting sand prior to the packing into the cavity.
- To attain the above object, in the present invention, casting sand in a blow head is stirred with a stirrer prior to its blowing and packing into the cavity until the stirring resistance of the stirrer enters within a predetermined range corresponding to an optimum bulk density range wherein the kinetic energy of the casting sand is maximised during blowing.
- Specifically, a method for making a casting mold of the present invention comprises: a blowing and packing step of feeding pressurized gas into a receiver that is provided in a blow head and accommodates gas-curing casting sand, thereby blowing the casting sand in the receiver into a cavity in molding dies through a blow nozzle that is provided in the blow head and communicates with the receiver and packing the casting sand into the cavity; a curing step of, after the blowing and packing step, introducing curing gas into the cavity to cure the casting sand packed in the cavity; and a stirring step of, before the blowing and packing step, stirring the casting sand in the receiver with a stirrer until the stirring resistance of the stirrer enters within a predetermined range corresponding to an optimum bulk density range wherein the kinetic energy of the casting sand is maximised during blowing.
- Thus, prior to the blowing and packing of casting sand into the cavity, the casting sand in the receiver is stirred and unstiffened. If the bulk density of casting sand thus stirred is too high, the casting sand clogs the blow nozzle and thereby becomes difficult to get out of the blow nozzle. On the contrary, if the casting sand is excessively unstiffened to reach an excessively small bulk density, only the pressurized gas quickly blows out through the blow nozzle and, also in this case, the casting sand becomes difficult to get out of the blow nozzle. In other words, there exists an optimum bulk density range within which casting sand can efficiently blow out through the blow nozzle. On the other hand, if casting sand in the receiver is not stirred, its bulk density is generally higher than the optimum bulk density range. In addition, as the number of blowing and packing steps carried out increases, the bulk density of casting sand becomes higher and higher owing to pressures applied from pressurized gas. To avoid this, prior to the blowing and packing step, casting sand in the receiver is stirred by the stirrer to bring the bulk density of casting sand into the optimum bulk density range. Specifically, the stirring resistance of the stirrer is in correspondence with the bulk density of casting sand so that as the bulk density increases, the stirring resistance becomes higher. Therefore, if a range of stirring resistances corresponding to the optimum bulk density range is set to the predetermined range and casting sand is stirred until the stirring resistance enters within the predetermined range, the optimum bulk density range is reached. Thus, in the blowing and packing step, casting sand is constantly well packed into the cavity. Furthermore, in the stirring step, casting sand is simply stirred without using air or a cutter and the solvent coated on the sand particles is not reduced. This is rather preferable because the binder, the solvent and sand are further uniformly mixed.
- In the above casting mold making method, preferably, the stirring step, the blowing and packing step and the curing step are sequentially repeated and the predetermined range is set in each stirring step. More preferably, the predetermined range is set based on the amount of casting sand in the receiver in each stirring step.
- Thus, the predetermine range can be appropriately set based on the amount of casting sand in the receiver in each stirring step. Specifically, when the blowing and packing step is carried out once, the amount of casting sand in the receiver is reduced by the amount of casting sand packed into the cavity. If in this case no casting sand is supplementally fed into the receiver, the amount of casting sand in the receiver in the next stirring step differs from that in the previous stirring step. If the amount of casting sand changes thus, the relation between the bulk density of casting sand and the stirring resistance of the stirrer also changes. However, since in the present invention the range of stirring resistances corresponding to the optimum bulk density range can be set to the predetermined range, this provides good, constant packability in every stirring step.
- Furthermore, in the above casting mold making method, preferably, the casting sand contains a binder and a solvent and the method further comprises a solvent feed step of, before or during the stirring step, supplementally feeding the solvent into the receiver.
- Thus, particularly in repeating the stirring step, the blowing and packing step and the curing step, the solvent coated on the sand particles can be prevented from being reduced. Specifically, in the blowing and packing step, pressurized air is fed into the receiver in order to blow and pack casting sand into the cavity, whereby the solvent on the sand particles is blown away and reduced to a certain extent by the pressurized gas. However, since in the present invention the amount of solvent reduced can be supplementally fed, this prevents the quality of a produced casting mold from being degraded. Even if the solvent is supplementally fed thus, the binder, the solvent and sand can be stirred uniformly by stirring in the stirring step, which avoids that the solvent becomes locally excessive in the receiver.
- A casting mold making system of the present invention includes a blow head having a receiver for accommodating gas-curing casting sand and a blow nozzle communicating with the receiver and a pressurized gas feed system for feeding pressurized gas into the receiver of the blow head and is configured to feed pressurized gas into the receiver through the pressurized gas feed system and thereby blow the casting sand in the receiver through the blow nozzle into the cavity and pack the casting sand into the cavity. The casting mold making system further comprises: a stirrer for stirring the casting sand in the receiver; a stirrer drive unit for driving the stirrer; a stirring resistance detection device for detecting the stirring resistance of the stirrer; and an operation controller for controlling the operation of the stirrer drive unit, the operation controller being configured to, prior to the feeding of pressurized gas into the receiver through the pressurized gas feed system, operate the stirrer drive unit until the stirring resistance detected by the stirring resistance detection device enters within a predetermined range.
- Preferably, the above casting mold making system further comprises a casting sand amount detection device for detecting the amount of casting sand in the receiver, wherein the operation controller is configured to set the predetermined range based on the amount of casting sand detected by the casting sand amount detection device.
- Furthermore, in the above casting mold making system, preferably, the casting sand contains a binder and a solvent, the casting mold making system further comprises a solvent spray device for supplementally feeding, under the control of the operation controller, the solvent into the receiver by spraying, and the operation controller is configured to, before or during the operation of the stirrer drive unit, operate the solvent spray device to supplementally feed the solvent into the receiver.
- According to the above configurations of the casting mold making system, the above casting mold making method can be easily implemented and the same operations and effects as according to the above casting mold making method can be obtained.
-
-
Figure 1 is a schematic block diagram showing a casting mold making system according to an embodiment of the present invention. -
Figure 2 is a graph showing the relation between the bulk density of casting sand in a receiver and the kinetic energy of casting sand blown out through blow nozzles. -
Figure 3 is a graph showing the relation between the bulk density of casting sand in the receiver and the stirring resistance of a stirrer. -
Figure 4 is a flowchart showing a processing procedure of a controller. - An embodiment of the present invention will be described below with reference to the drawings.
-
Figure 1 schematically shows a casting mold making system according to an embodiment of the present invention. The casting mold making system is a cold box casting mold making system including ablow head 1 with areceiver 2 for accommodating gas-curingcasting sand 41. The castingsand 41 contains a binder composed of a phenol resin and a polyisocyanate compound and a solvent so that the surfaces of sand particles are coated with the binder and the solvent. Examples of the phenol resin in the binder include phenol resins having at least one benzyl ether group in its molecule, novolak resins and their derivative resins. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, hexamethylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate. The solvent is an organic solvent including aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ketones, esters, ethers and alcohols, or their mixtures. - The casting
sand 41 is fed from a kneading unit 3 disposed above thereceiver 2 to thereceiver 2. Specifically, the binder, the solvent and sand are charged into the kneading unit 3 and uniformly kneaded by akneader 4 driven into rotation in the kneading unit 3, thereby providing castingsand 41 in which sand particles are coated with the binder and the solvent as described above. Ashutter 5, opened and closed by ashutter drive mechanism 6, is disposed between thereceiver 2 and the kneading unit 3. The operation of theshutter drive mechanism 6 is controlled by a controller 31. When theshutter 5 is opened by theshutter drive mechanism 6, the castingsand 41 falls down from the kneading unit 3 by its own weight and is fed to thereceiver 2. - The bottom of the
blow head 1 is provided with a plurality ofblow nozzles 9, communicated with thereceiver 2, for blowing out castingsand 41 in thereceiver 2 therethrough. Theblow nozzles 9 are presented to acavity 36 created by a plurality of molding dies 35 set up below the casting mold making system. Castingsand 41 blown out through theblow nozzles 9 is packed into thecavity 36 to have a shape of a casting mold to be made by the casting mold making system. Casting molds made by the casting mold making system include casting molds for cylinder blocks or cylinder heads and cores for water jackets of the cylinder heads. - An upper portion of any one of the side walls defining the
receiver 2 in theblow head 1 is formed with an air feed port 1a through which pressurized air serving as pressurized gas is fed into thereceiver 2. The air feed port 1a is connected to anair tank 12 through asolenoid valve 11 whose actuation is controlled by the controller 31. Theair tank 12 is supplied with air in the factory while the air to theair tank 12 is kept at a constant pressure (about 0.2 MPa to about 1 MPa) by a regulator (not shown). The air supplied is stored as the pressurized air in theair tank 12. When thesolenoid valve 11 is actuated, the pressurized air in theair tank 12 is fed into thereceiver 2, whereby castingsand 41 in thereceiver 2 is blown through theblow nozzles 9 into thecavity 36 in the molding dies 35 and packed into thecavity 36. Thus, thesolenoid valve 11, theair tank 12 and the controller 31 constitute pressurized gas feed system for feeding pressurized gas into thereceiver 2. The pressurized air, blown into thecavity 36 together with the castingsand 41, is vented out of thecavity 36 throughair vents 37 attached to the bottom of the molding die 35. - An upper portion of any one of the side walls defining the
receiver 2 is formed with asolvent feed port 1b through which the solvent is supplementally fed into thereceiver 2. Thesolvent feed port 1b is connected to asolvent spray device 15 for supplementally feeding the solvent into thereceiver 2 by spraying it. The operation of thesolvent spray device 15 is controlled by the controller 31 and operates prior to the actuation of adrive motor 22a of the after-mentionedstirrer drive unit 22 to supplementally feed a given amount of solvent into thereceiver 2 by spraying. Specifically, the last time when castingsand 41 was blown and packed into thecavity 36, the solvent on the sand particles has been blown away and reduced to a certain extent by pressurized air. Therefore, the solvent is supplementally fed into thereceiver 2 by substantially the same amount as the amount of solvent reduced. - An upper part of the interior of the
receiver 2 of theblow head 1 is provided with a castingsand amount sensor 16 serving as a casting sand amount detection device for detecting the amount of castingsand 41 in thereceiver 2. In this embodiment, the castingsand amount sensor 16 is configured to emit infrared rays downward, receive infrared rays reflected from the top surface of the castingsand 41 and detect the amount of castingsand 41 in thereceiver 2 based on the intensity of the reflected infrared rays. However, any appropriate sensors having other configurations can also be employed. Data on the amount of castingsand 41 in thereceiver 2 detected by the castingsand amount sensor 16 is input to the controller 31. - Furthermore, a lower part of the interior of the
receiver 2 of theblow head 1 is provided with astirrer 21 for stirring castingsand 41 in thereceiver 2. Thestirrer 21 is an element forunstiffening casting sand 41 to bring it to an optimum bulk density as described later. Thestirrer 21 is composed of arotary shaft 21a vertically extending and rotatably supported, abase plate 21b fixed to the lower end of therotary shaft 21a and extending horizontally, and a plurality of stirringbars 21c disposed on thebase plate 21b. The upper end of therotary shaft 21a is connected to thestirrer drive unit 22. Thestirrer drive unit 22, whose detailed configuration is not described here, includes adrive motor 22a, a connecting member made, for example, of flexible wire and connecting the rotary shaft of thedrive motor 22a to therotary shaft 21a, and a drive circuit for driving thedrive motor 22a. The drive circuit includes a current detectingelement 22b for detecting the value of current flowing into thedrive motor 22a. - The operation of the
drive motor 22a of thestirrer drive unit 22 is controlled by the controller 31. Specifically, the controller 31 constitutes an operation controller for controlling the operation of thedrive motor 22a of thestirrer drive unit 22. During operation of thedrive motor 22a, data on the value of current detected by the current detectingelement 22b is input to the controller 31. - The controller 31 is configured to, prior to the blowing and packing of casting
sand 41 in thereceiver 2 into thecavity 36, operate thedrive motor 22a until the stirring resistance of thestirrer 21 enters within a predetermined range. In this embodiment, the stirring resistance of thestirrer 21 is detected by the current detectingelement 22b. Specifically, the value of current of thedrive motor 22a is in correspondence with the motor torque required to rotate thestirrer 21, i.e., the stirring resistance of thestirrer 21, so that as the stirring resistance of thestirrer 21 increases, the value of current of thedrive motor 22a increases. Therefore, a predetermined range of current values is previously set corresponding to the predetermined range of stirring resistances and thedrive motor 22a is operated until the value of current detected by the current detectingelement 22b enters within the predetermined range of current values. Thus, the current detectingelement 22b constitutes a stirring resistance detection device for detecting the stirring resistance of thestirrer 21. - The predetermined range of stirring resistances, i.e., the predetermined range of current values, is set at a range within which casting
sand 41 in thereceiver 2 can efficiently blow out through theblow nozzles 9. In this respect, the relation between the bulk density of castingsand 41 in thereceiver 2 and the kinetic energy thereof blown out through theblow nozzles 9 was examined by changing the bulk density of castingsand 41 in thereceiver 2 while keeping the amount thereof constant. The kinetic energy was determined from the mass of the castingsand 41 in thereceiver 2 and the velocity of it blown out through theblow nozzles 9. The examination results are shown inFigure 2. Figure 2 indicates that there exists a bulk density range within which the kinetic energy reaches the maximum value or near the maximum value, in other words, an optimum bulk density range within which castingsand 41 efficiently blows out through theblow nozzles 9. The reason for this is as follows. If the bulk density of castingsand 41 is excessively high, castingsand 41 clogs theblow nozzles 9 and thereby becomes difficult to get out of theblow nozzles 9. On the other hand, if castingsand 41 is excessively unstiffened to reach an excessive low bulk density, only pressurized air quickly blows out through theblow nozzles 9 and, also in this case, castingsand 41 becomes difficult to get out of theblow nozzles 9. - Furthermore, the relation between the bulk density of casting
sand 41 and the stirring resistance of the stirrer 21 (the motor torque of the drive motor) was also examined. The examination results are shown inFigure 3. Figure 3 indicates that the stirring resistance of thestirrer 21 is in correspondence with the bulk density of castingsand 41 so that as the bulk density increases, the stirring resistance also increases. Therefore, the blowing of castingsand 41 into thecavity 36 will do well if a range of stirring resistances corresponding to the optimum bulk density range is set at the above-described predetermined range of stirring resistances. A range of current values corresponding to the predetermined range of stirring resistance can be set at the above-described predetermined range of current values. - The optimum bulk density range varies depending upon the amount of casting
sand 41 in thereceiver 2. Therefore, the amount of castingsand 41 in thereceiver 2 is detected by the castingsand amount sensor 16. Specifically, an examination is previously made of the relation between the amount of castingsand 41 and the optimum bulk density range (i.e., the predetermined range of current values), the examination results are mapped in a table and the table is stored in the controller 31. When receiving data on the amount of castingsand 41 from the castingsand amount sensor 16 during operation of the casting mold making system, the controller 31 sets, based on the table, a predetermined range of current values corresponding to the detected amount of castingsand 41. - When the amount of casting
sand 41 detected by the castingsand amount sensor 16 reaches below a predetermined amount, i.e., when the remaining amount of castingsand 41 gets too low to provide enough to pack castingsand 41 into thecavity 36, the controller 31 actuates theshutter drive mechanism 6 to feed castingsand 41 from the kneading unit 3 into thereceiver 2. - Next, a processing procedure of the controller 31 is described with reference to the flowchart of
Figure 4 . - In the first step S1, the
solvent spray device 15 is operated to supplementally feed the given amount of solvent into thereceiver 2 by spraying it. In the next step S2, a predetermined range of current values is set. Specifically, the predetermined range of current values is set based on the amount of castingsand 41 in thereceiver 2 detected by the castingsand amount sensor 16 and the table. - Subsequently, the
drive motor 22a of thestirrer drive unit 22 is operated in step S3 and it is then determined in step S4 whether the value of current detected by the current detectingelement 22b is within the predetermined range of current values. - If the determination in step S4 is NO, the procedure goes back to step S3. If the determination in step S4 is YES, the procedure goes to step S5 to stop the
drive motor 22a and then goes to step S6 to actuate thesolenoid valve 11 and thereby feed pressurized air in theair tank 12 into thereceiver 2. - In the next step S7, it is determined whether the amount of casting
sand 41 detected by the castingsand amount sensor 16 is smaller than the predetermined amount. In the determination in step S7 is NO, the procedure ends. If the determination in step S7 is YES, the procedure goes to step S8 to actuate theshutter drive mechanism 6 and then ends. - Next, a description is given of a method for making a casting mold using the above casting mold making system.
- First, the molding dies 35 are set up in the casting mold making system and the casting mold making system is activated by switch operation or in other manners. Thus, the given amount of solvent is supplementally fed into the receiver 2 (a solvent feed step). Then, the
base plate 21b of thestirrer 21 rotates about therotary shaft 21a, whereby the plurality of stirringbars 21c on thebase plate 21b stir the castingsand 41 in thereceiver 2 to unstiffen it (a stirring step). During the stirring, the binder, the solvent (including supplementally fed solvent) and sand in thereceiver 2 are uniformly mixed. At the beginning of operation of thestirrer 21, the bulk density of castingsand 41 in thereceiver 2 is usually higher than the optimum bulk density range. However, with increasing duration of stirring of thestirrer 21, the bulk density gradually decreases and then reaches the optimum bulk density range. When the optimum bulk density range is reached, the value of current detected by the current detectingelement 22b enters within the predetermined range of current values and the operation of thestirrer 21 is stopped. - Subsequently, pressurized air in the
air tank 12 is fed into thereceiver 2, whereby castingsand 41 in thereceiver 2 is blown through theblow nozzles 9 into thecavity 36 in the molding dies 35 and packed into it (a blowing and packing step). Since the bulk density of castingsand 41 has been set, prior to the blowing and packing step, at the optimum bulk density range within which castingsand 41 can efficiently blow out through theblow nozzles 9, the castingsand 41 is well packed into thecavity 36 in the blowing and packing step. - After the blowing and packing step, in this embodiment, the molding dies 35 are moved to an unshown curing gas introduction device disposed separately from the
blow head 1 in order to introduce curing gas into thecavity 36 in the molding dies 35, and placed in the curing gas introduction device. Then, curing gas (such as triethylamine gas) is introduced into thecavity 36 to cure the castingsand 41 packed in the cavity 36 (a curing step), thereby completing the making of a high-quality casting mold. - Then, the molding dies 35 may be set up again in the casting mold making system in order to make another casting mold. In this case, when the casting mold making system is activated again, the solvent feed step, the stirring step and the blowing and packing step are similarly sequentially carried out. The solvent on the sand particles, however, has been blown away and reduced to a certain extent by pressurized air in the previous blowing and packing step. Therefore, in this solvent feed step, the solvent is supplementally fed by substantially the same amount as the amount of solvent reduced.
- Then, in the next stirring step, the binder, the solvent (including supplementally fed solvent) and sand in the
receiver 2 are further uniformly mixed. Furthermore, the amount of castingsand 41 generally becomes smaller than that in the previous stirring step (but becomes larger when castingsand 41 is fed from the kneading unit 3 into the receiver 2). Therefore, in such cases, the optimum bulk density range (the predetermined range of current values) corresponding to the amount of castingsand 41 is set again. In this manner, in each stirring step, the optimum bulk density range (the predetermined range of current values) is set based on the amount of castingsand 41 in thereceiver 2. In each stirring step, the bulk density of castingsand 41 in thereceiver 2 at the beginning of the stirring step is higher than the optimum bulk density range owing to the pressure applied from pressurized air in the previous blowing and packing step but the bulk density thereof at the end of the stirring step enters within the optimum bulk density range corresponding to the amount of castingsand 41. Thus, in the next blowing and packing step, the castingsand 41 can be well packed into thecavity 36. After the blowing and packing step, similarly, the curing step is carried out. If the above steps are repeated in this manner, a large number of casting molds can be made. - When the amount of casting
sand 41 in thereceiver 2 becomes smaller than the predetermined amount after the blowing and packing step, theshutter drive mechanism 6 is actuated to put theshutter 5 to an open position, whereby castingsand 41 is fed from the kneading unit 3 into thereceiver 2. - As described above, in this embodiment, casting
sand 41 is stirred by thestirrer 21 prior to the blowing and packing of castingsand 41 into thecavity 36, whereby the bulk density of castingsand 41 enters within the optimum bulk density range within which castingsand 41 can efficiently blow out through theblow nozzles 9. Therefore, castingsand 41 can be constantly well packed into thecavity 36. - Furthermore, since in the stirring
step casting sand 41 is simply stirred without using air or a cutter, the solvent on the sand particles is not reduced in the stirring step. Although the solvent on the sand particles is reduced to a certain extent in the previous blowing and packing step, the amount of solvent thus reduced is supplementally fed by operating thesolvent spray device 15. This prevents the quality of a produced casting mold from being degraded. - Although in the above embodiment the stirring resistance of the
stirrer 21 is detected by the current detectingelement 22b for detecting the value of current flowing into thedrive motor 22a of thestirrer drive unit 22, the manner of detecting the stirring resistance of thestirrer 21 is not limited to this. For example, thestirrer 21 may be provided with a torque sensor and its stirring resistance may be detected by the torque sensor. - Although in the above embodiment the amount of casting
sand 41 is detected by the castingsand amount sensor 16 in each stirring step, the castingsand amount sensor 16 may not be used, for example, in the case of making a large number of casting molds of the same configuration. Specifically, in this case, the amount of castingsand 41 reduced in a single blowing and packing step is substantially constant. On the basis of this fact, if after every given times of the blowing and packing step a given amount of casting sand 41 (i.e., the given times multiplied by the amount of casting sand reduced in a single blowing and packing step) is fed from the kneading unit 3 into thereceiver 2, the respective amounts of castingsand 41 in the respective stirring steps in the given times can be determined. Therefore, if the controller 31 stores the respective optimum bulk density ranges (the respective predetermined ranges of current values) corresponding to the respective amounts of castingsand 41 in the respective stirring steps, a large number of casting molds of the same configuration can be made without using the castingsand amount sensor 16. - Furthermore, although in the above embodiment the solvent is supplementally fed into the
receiver 2 prior to the stirring step, the solvent may be supplementally fed during the stirring step. Just after castingsand 41 is fed from the kneading unit 3 into thereceiver 2 by the actuation of theshutter drive mechanism 6, the solvent may not be fed or the amount of solvent fed may be small. Alternatively, the solvent feed step antecedent to each stirring step may not be eliminated. This should not be a serious problem because the amount of solvent reduced in each blowing and packing step is very small.
Claims (7)
- A method for making a casting mold, comprising:a blowing and packing step of feeding pressurized gas into a receiver (2) that is provided in a blow head (1) and accommodates gas-curing casting sand (41), thereby blowing the casting sand in the receiver into a cavity (36) in molding dies (35) through a blow nozzle (9) that is provided in the blow head (1) and communicates with the receiver (2) and packing the casting sand (41) into the cavity (36);a curing step of, after the blowing and packing step, introducing curing gas into the cavity (36) to cure the casting sand (41) packed in the cavity (36); anda stirring step of, before the blowing and packing step, stirring the casting sand (41) in the receiver (2) with a stirrer (21) until the stirring resistance of the stirrer (21) enters within a predetermined range,characterized in thatthe predetermined range corresponds to a bulk density range, wherein within said bulk density range, the kinetic energy of the casting sand (41) reaches a maximum value or near the maximum value when the casting sand (41) is blown out through the blow nozzle (9).
- The method of claim 1, wherein
the stirring step, the blowing and packing step and the curing step are sequentially repeated, and
the predetermined range is set in each stirring step. - The method of claim 2, wherein the predetermined range is set based on the amount of casting sand (41) in the receiver (2) in each stirring step.
- The method of any of claims 1 to 3, wherein
the casting sand (41) contains a binder and a solvent, and
the method further comprises a solvent feed step of, before or during the stirring step, supplementally feeding the solvent into the receiver (2). - A casting mold making system which includes a blow head (1) having a receiver (2) for accommodating gas-curing casting sand (41) and
a blow nozzle (9) communicating with the receiver and
a pressurized gas feed system, which is configured to feed pressurized gas into the receiver (2) of the blow head (1) and thereby blow the casting sand (41) in the receiver (2) through the blow nozzle (9) into a cavity (36) in molding dies (35) and pack the casting sand (41) into the cavity (36), the casting mold making system further comprising:a stirrer (21) for stirring the casting sand (41) in the receiver (2);a stirrer drive unit (22) for driving the stirrer (21); anda curing gas introduction device, wherein the curing gas introduction device is designed to introduce curing gas into the cavity (36) to cure the casting sand (41) packed in the cavity (36);characterized bya stirring resistance detection device (22b) for detecting the stirring resistance of the stirrer (21); andan operation controller (31), for controlling the operation of the stirrer drive unit (22), being configured to, prior to the feeding of pressurized gas into the receiver (2) through the pressurized gas feed system, operate the stirrer drive unit (22) until the stirring resistance detected by the stirring resistance detection device (22b) enters within a predetermined range;wherein the predetermined range corresponds to a bulk density range, wherein within said bulk density range, the kinetic energy of the casting sand (41) reaches a maximum value or near the maximum value when the casting sand (41) is blown out through the blow nozzle (9). - The casting mold making system of claim 5, further comprising
a casting sand amount detection device (16), which is designed for detecting the amount of casting sand in the receiver (2),
wherein the operation controller (31) is configured to set the predetermined range based on the amount of casting sand (41) detected by the casting sand amount detection device (16). - The casting mold making system of claim 5 or 6, wherein
the casting sand (41) contains a binder and a solvent,
the casting mold making system further comprises a solvent spray device (15), which is designed for supplementally feeding, under the control of the operation controller (31), the solvent into the receiver (2) by spraying, and
the operation controller (31) is configured to, before or during the operation of the stirrer drive unit (22), operate the solvent spray device (15) to supplementally feed the solvent into the receiver (2).
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JP2006063022A JP4706511B2 (en) | 2006-03-08 | 2006-03-08 | Mold making method and apparatus |
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JPS601100B2 (en) * | 1978-09-18 | 1985-01-11 | 新東工業株式会社 | mold making machine |
US4570694A (en) * | 1982-01-25 | 1986-02-18 | Lund Robert S | Mold-blowing apparatus |
JPS58196145A (en) * | 1982-05-08 | 1983-11-15 | Sintokogio Ltd | Mold forming method |
DE4208647C2 (en) * | 1992-03-18 | 1995-06-29 | Hottinger Adolf Masch | Device for shooting foundry cores or molds with molding materials |
JPH07232233A (en) * | 1994-02-23 | 1995-09-05 | Nagakawara Kinzoku:Kk | Method reconditioning molding sand |
JPH08257679A (en) * | 1995-03-24 | 1996-10-08 | Sintokogio Ltd | Device for continuously kneading molding sand |
JP3341626B2 (en) * | 1997-04-17 | 2002-11-05 | 三菱自動車工業株式会社 | Cold box molding method |
BR0104490A (en) * | 2000-02-17 | 2002-05-21 | Sintokogio Ltd | Apparatus and method for introducing molding sand into a mold space defined by a standard plate |
US20040031580A1 (en) * | 2002-08-15 | 2004-02-19 | Smith Douglas W. | Contour mold casting method |
-
2006
- 2006-03-08 JP JP2006063022A patent/JP4706511B2/en active Active
-
2007
- 2007-02-26 CN CN2007100847018A patent/CN101032735B/en not_active Expired - Fee Related
- 2007-02-27 DE DE602007013830T patent/DE602007013830D1/en active Active
- 2007-02-27 EP EP07004056A patent/EP1832358B8/en not_active Ceased
- 2007-03-06 US US11/682,591 patent/US20070209772A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
DE602007013830D1 (en) | 2011-05-26 |
JP2007237234A (en) | 2007-09-20 |
JP4706511B2 (en) | 2011-06-22 |
EP1832358B8 (en) | 2011-09-21 |
US20070209772A1 (en) | 2007-09-13 |
CN101032735A (en) | 2007-09-12 |
CN101032735B (en) | 2011-07-20 |
EP1832358A1 (en) | 2007-09-12 |
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