EP2022577A1 - Method for producing salt core for casting and salt core for casting - Google Patents
Method for producing salt core for casting and salt core for casting Download PDFInfo
- Publication number
- EP2022577A1 EP2022577A1 EP07743674A EP07743674A EP2022577A1 EP 2022577 A1 EP2022577 A1 EP 2022577A1 EP 07743674 A EP07743674 A EP 07743674A EP 07743674 A EP07743674 A EP 07743674A EP 2022577 A1 EP2022577 A1 EP 2022577A1
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- EP
- European Patent Office
- Prior art keywords
- melt
- salt
- expendable
- core
- salt core
- 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.)
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- 150000003839 salts Chemical group 0.000 title claims abstract description 136
- 238000005266 casting Methods 0.000 title claims description 64
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 239000000155 melt Substances 0.000 claims abstract description 83
- 239000011833 salt mixture Substances 0.000 claims abstract description 49
- 239000007788 liquid Substances 0.000 claims abstract description 40
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims abstract description 6
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
- 239000007790 solid phase Substances 0.000 claims description 17
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 13
- 239000007791 liquid phase Substances 0.000 claims description 13
- 150000001450 anions Chemical class 0.000 claims description 12
- 150000001768 cations Chemical class 0.000 claims description 12
- 229910001414 potassium ion Inorganic materials 0.000 claims description 12
- 229910001415 sodium ion Inorganic materials 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 5
- 238000007711 solidification Methods 0.000 abstract description 31
- 229910052751 metal Inorganic materials 0.000 abstract description 29
- 239000002184 metal Substances 0.000 abstract description 29
- 230000008023 solidification Effects 0.000 abstract description 29
- 238000004512 die casting Methods 0.000 abstract description 14
- 230000003247 decreasing effect Effects 0.000 abstract description 4
- 239000000498 cooling water Substances 0.000 description 42
- 238000005452 bending Methods 0.000 description 40
- 238000012360 testing method Methods 0.000 description 31
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 24
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 24
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 23
- 238000000465 moulding Methods 0.000 description 16
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 16
- 239000000203 mixture Substances 0.000 description 15
- 238000005259 measurement Methods 0.000 description 14
- 238000000034 method Methods 0.000 description 14
- 238000003756 stirring Methods 0.000 description 14
- 238000002347 injection Methods 0.000 description 12
- 239000007924 injection Substances 0.000 description 12
- 238000002844 melting Methods 0.000 description 12
- 230000008018 melting Effects 0.000 description 12
- 229910000029 sodium carbonate Inorganic materials 0.000 description 12
- 239000011780 sodium chloride Substances 0.000 description 12
- 239000001103 potassium chloride Substances 0.000 description 11
- 235000011164 potassium chloride Nutrition 0.000 description 11
- 238000004891 communication Methods 0.000 description 10
- 230000013011 mating Effects 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 238000004090 dissolution Methods 0.000 description 8
- 229910000027 potassium carbonate Inorganic materials 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000007598 dipping method Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000001746 injection moulding Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 3
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical compound [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 description 1
- 235000015895 biscuits Nutrition 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 235000011148 calcium chloride Nutrition 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- PQLXHQMOHUQAKB-UHFFFAOYSA-N miltefosine Chemical compound CCCCCCCCCCCCCCCCOP([O-])(=O)OCC[N+](C)(C)C PQLXHQMOHUQAKB-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 235000007715 potassium iodide Nutrition 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000012744 reinforcing agent Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- -1 sodium and potassium Chemical class 0.000 description 1
- 235000009518 sodium iodide Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/10—Cores; Manufacture or installation of cores
- B22C9/105—Salt cores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
- B22D29/002—Removing cores by leaching, washing or dissolving
Abstract
Description
- The present invention relates to a method of manufacturing a water soluble expendable salt core for casting, and an expendable salt core for casting.
- As is known well, casting such as aluminum high pressure die casting (HPDC) is a technique that injects a molten aluminum alloy into a metal mold at high speed under a high pressure to cast a near-net-shape structure. In this casting, when molding a cast product having a hollow structure, e.g., a water cooling water jacket in the closed-deck type cylinder block of an internal combustion engine, an expendable core is used. The expendable core used in such a case must have a strength that can withstand a high pressure and high temperature because it may be subject to a large impact or impulse force fluctuation upon collision of a molten metal injected from the gate at high speed mold filling and because a high static compressive casting pressure is applied until solidification completion. After casting, the expendable core is removed from the cast product. When the cast product has a complicated internal structure, if a generally used phenol resin bonded sand core is used as the expendable core, it is not easy to remove. In contrast to this, a water soluble expendable salt core is available as the expendable core that can be removed by dissolution with, e.g., high-temperature water (reference 1: Japanese Patent Laid-Open No.
48-039696 50-136225 52-010803 - The expendable salt core as described above is formed by using a salt mixture of, e.g., sodium carbonate (Na2CO3), potassium chloride (KCl), and sodium chloride (NaCl), melting these components, and molding. Hence, a high static compressive casting pressure resistance is obtained, and workability and stability of dimension accuracy in casting are improved.
- When an expendable fused salt core is formed by melting a salt and casting, however, the formation of a shrinkage cavity, micro-porosity, small heat crack, and the like would be caused in the salt core due to a change in volume such as solidification shrinkage occurring in the solidification process. It is therefore not easy to mold the expendable fused salt core conforming to the mold precisely. Also, depending on the composition of the respective components, the resultant melting point is 700°C or more, which is not suitable for molding by melting. In this manner, with the prior art, an expendable fused salt core cannot be manufactured easily by casting using a molten salt.
- The present invention has been made to solve the above problems, and has as its object to facilitate manufacture of a water soluble expendable salt core for casting which is formed of a salt cast product obtained by molding after melting salts such as sodium and potassium.
- A method of manufacturing an expendable salt core for casting according to the present invention comprises at least the first step of heating a salt mixture containing at least a potassium salt and a sodium salt to form a melt in a solid-liquid coexisting state in which a solid phase and a liquid phase coexist, the second step of charging the melt in the solid-liquid coexisting state into a core mold, and the third step of solidifying the melt in the mold to mold an expendable salt core for casting. Therefore, at the point when the mold is charged with the melt, the melt is partly solidified.
- An expendable salt core for casting according to the present invention is molded by heating a salt mixture containing at least a potassium salt and a sodium salt to form a melt in a solid-liquid coexisting state in which a solid phase and a liquid phase coexist, charging the melt in the solid-liquid coexisting state into a core mold, and solidifying the melt in the mold. This expendable salt core for casting comprises, e.g., a core to mold a water jacket for water cooling a closed-deck type cylinder block of engine.
- According to the present invention, an expendable salt core is cast using a melt in a solid-liquid coexisting state. Therefore, a water soluble expendable salt core for casting made of a salt cast product, which is molded by melting salts such as sodium and potassium, can be manufactured easily.
-
-
Fig. 1 is a perspective view of a cylinder block which is cast using an expendable salt core for casting according to the present invention; -
Fig. 2 is a photograph which is obtained by a metallographic microscope (optical microscope) and shows the state of the solidification structure of asalt core 2; -
Fig. 3 is a graph showing the temperature dependence of the solid phase ratio of a melt in a semi-solidified state; -
Fig. 4 is a photograph of a solidification structure obtained by a scanning electron microscope when a salt mixture with a composition containing a large amount of chloride is melted and molded, and solidified without stirring; -
Fig. 5 is a photograph of a solidification structure obtained by a scanning electron microscope when a salt mixture with a composition containing a large amount of carbonate is melted and molded, and solidified without stirring; -
Fig. 6A is a graph showing the bending strengths of bending test pieces of sample Nos. 1 to 9; -
Fig. 6B is a graph showing the bending strengths of bending test pieces of sample Nos. 10 to 12; -
Fig. 6C is a graph showing the bending strengths of bending test pieces of sample Nos. 13 to 17; -
Fig. 7A is a graph showing the bending strengths of bending test pieces of sample Nos. 18 to 23; -
Fig. 7B is a graph showing the bending strengths of bending test pieces of sample Nos. 24 to 27; -
Fig. 8 is a phase diagram showing the relationship among the cation ratio of potassium ions vs. sodium ions, the anion ratio of carbonate ions vs. chloride ions, and the liquidus temperature; -
Fig. 9A is a view showing the state of a test piece used for bending strength measurement; -
Fig. 9B is a sectional view showing part of the test piece used for bending strength measurement; -
Fig. 10 is a view for explaining bending strength measurement; -
Fig. 11 is a photograph for explaining pressure measurement portions in the cavity of an expendable salt core during injection molding; -
Fig. 12 is a graph showing the measurement result of the pressure in the cavity of the expendable salt core during injection molding; -
Fig. 13 is a perspective view of another cylinder block which is cast using an expendable salt core for casting according to the present invention; and -
Fig. 14 is a photograph of anexpendable salt core 1302 shown inFig. 13 . - The embodiment of the present invention will be described hereinafter with reference to the drawings. First, how an expendable salt core for casting according to the embodiment of the present invention is used will be described with reference to
Fig. 1. Fig. 1 is a partially cutaway perspective view of a closed-deck type cylinder block which is cast using the expendable salt core for casting according to the present invention. Referring toFig. 1 ,reference numeral 1 denotes a closed-deck type cylinder block of engine, which is made of an aluminum alloy and cast using anexpendable salt core 2 as an expendable salt core for casting according to the present invention. Thecylinder block 1 is part of a water cooling 4-cycle 4-cylinder engine for a motorcycle which is molded into a predetermined shape by high pressure die casting (HDPC). - The
cylinder block 1 shown inFig. 1 integrally has fourcylinder bores 3, acylinder body 4 having thecylinder bores 3, and anupper crank case 5 extending downward from the lower end of thecylinder body 4. A lower crank case (not shown) is attached to the lower end of theupper crank case 5. Theupper crank case 5, together with the lower crank case, rotatably, axially supports a crank shaft (not shown) through a bearing. - The
cylinder body 4 is a so-called closed-deck-type cylinder body, and has awater jacket 6 which is formed in it using theexpendable salt core 2. Thewater jacket 6 is formed to include a cooling waterpassage forming portion 7, coolingwater inlet port 8, maincooling water passage 9, andcommunication passage 10. The cooling waterpassage forming portion 7 projects on one side of thecylinder body 4 and extends in the direction in which the cylinder bores 3 line up. The coolingwater inlet port 8 is formed in the cooling waterpassage forming portion 7. The maincooling water passage 9 is formed to communicate with a cooling water distribution passage (not shown) formed in the cooling waterpassage forming portion 7 and cover all thecylinder bores 3. Thecommunication passage 10 extends upward inFig. 1 from the maincooling water passage 9 and opens to a mating surface 4a with respect to a cylinder head (not shown) at the upper end of thecylinder body 4. - The
water jacket 6 described above supplies cooling water flowing in from the coolingwater inlet port 8 to the maincooling water passage 9 around the cylinder bores through the cooling water distribution passage, and guides the cooling water from the maincooling water passage 9 to a cooling water passage in the cylinder head (not shown) through thecommunication passage 10. Since thewater jacket 6 is formed in this manner, thecylinder body 4 is covered with the ceiling wall (the wall that forms the mating surface 4a) of thecylinder body 4 except that thecommunication passage 10 of thewater jacket 6 opens to the mating surface 4a at the upper end to which the cylinder head is connected. Hence, a closed-deck-type arrangement is formed. - The
expendable salt core 2 to form thewater jacket 6 has a shape identical to that obtained by integrally connecting the respective portions of thewater jacket 6. InFig. 1 , thecylinder body 4 is partly cut away to facilitate understanding of the shape of the expendable salt core 2 (the shape of the water jacket 6). - The expendable salt core (salt core for casting) 2 according to this embodiment is formed using a plurality of types of salts such as sodium carbonate, sodium chloride, and potassium chloride by, e.g., die casting in a solid-liquid coexisting state such as a semi-solidified state into the shape of the
water jacket 6. Theexpendable salt core 2 may be formed by heating a salt mixture containing at least a potassium salt and a sodium salt to form a melt in a solid-liquid coexisting state in which a solid phase and liquid phase coexist, charging the melt into a core mold, and solidifying the melt in the mold. A method of manufacturing theexpendable salt core 2 will be described later in detail. - Note that the
expendable salt core 2 can be formed by a casting method other than die casting, e.g., gravity casting. In formation of theexpendable salt core 2 which employs die casting, first, a mixture consisting of a plurality of salts (to be described later) is melted by heating to obtain a melt. Then, the temperature of the melt is decreased to set the melt in a semi-solidified (solid-liquid coexisting) state. The melt in the semi-solidified state is injected into an expendable salt core forming metal mold under a high pressure and solidified. After solidification, the obtainedexpendable salt core 2 is taken out from the mold. - As shown in
Fig. 1 , in theexpendable salt core 2, thepassage forming portion 2a which forms the coolingwater inlet port 8 and the cooling water distribution passage, anannular portion 2b which surrounds the four cylinder bores 3, and a plurality ofprojections 2c extending upward from theannular portion 2b are formed integrally. Theprojections 2c form thecommunication passage 10 of thewater jacket 6. As is conventionally known, theexpendable salt core 2 is supported at a predetermined position in the metal mold (not shown) by a core print (not shown) during casting, and is removed by dissolution with hot water or vapor after casting. - To remove the
expendable salt core 2 after casting, thecylinder block 1 may be dipped in a dissolution tank (not shown) which contains dissolving liquid consisting of hydrochloric acid and hot water. When dipping thecylinder block 1 in the dissolving liquid, thepassage forming portion 2a and theprojections 2c exposed to the mating surface 4a, of theexpendable salt core 2 come into contact with the dissolving liquid and dissolve. The dissolved portions expand gradually until all the portions dissolve finally. In this core removing process, to promote dissolution of theexpendable salt core 2 left in thewater jacket 6, hot water or vapor may be sprayed under a pressure from a hole. In theexpendable salt core 2, in place of theprojections 2c, a core print may be inserted in portions where theprojections 2c are to be formed. - If hydrochloric acid is used in the process of removing the
expendable salt core 2 from thecylinder block 1 as a cast product, carbon dioxide gas foams. The foam provides a stirring function and promotes dissolution effectively. As theexpendable salt core 2 contains potassium carbonate and sodium carbonate, when it dissolves in water, the resultant water exhibits alkaline. This alkali state poses problems such as corrosion of thecylinder block 1 as an aluminum cast product. Regarding this problem, corrosion of the cylinder block can be prevented by adding hydrochloric acid to control pH to near 7. - The method of manufacturing the
expendable salt core 2 will now be described in detail. First, a case will be described in which the melt is not injected (pressure-injected) under a high pressure as in die casting, but flowed (poured) into the metal mold to manufacture the expendable salt core 2 (gravity casting). To form theexpendable salt core 2 of this embodiment, first, sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride are mixed and heated until they are melted, thus preparing a melt of a salt mixture. For example, when the salts are mixed such that a molar ratio XK+ (= [K+]/([Na+] + [K+]) x 100) of potassium ions in the entire cations is 33 mol% and that a molar ratio YCO3 2- (= [CO3 2-]/([CO3 2-] + [Cl-]) x 100) of carbonate ions in the entire anions is 67 mol%, the salt mixture dissolves at 647°C. For example, the salt mixture described above may be put in an alumina crucible and dissolved in an electric furnace. - Subsequently, when the temperature of the salt mixture accommodated in the crucible reached 647°C, which is a liquidus temperature or more, the crucible was taken out from the electric furnace and air-cooled. The cooling speed was 0.3°C to 1.2°C per sec. At this time, the salt mixture in the crucible was stirred with an alumina stirrer with a rotation speed of 3 rps, and was poured into the metal mold when the temperature of the melt of the salt mixture was 638°C. When the melt of the salt mixture is 638°C, the melt is in a semi-solidified state in which the solid phase and liquid phase coexist. The melt in this state is charged into a metal mold for an expendable salt core and solidified, and is taken out from the metal mold after solidification. In the above description, after the salt mixture was heated to set it in a liquid-phase-only state, it was cooled, thus obtaining a melt in a solid-liquid coexisting state. However, the present invention is not limited to this. A melt in the semi-solidified state may be obtained by heating the salt mixture to a semi-solidification temperature.
- The thus obtained
expendable salt core 2 had a strength (bending strength) of as high as 21.4 MPa to 24.6 MPa. The solidification structure of theexpendable salt core 2 comprised fine crystal particles as is seen from the photograph shown inFig. 2 which is obtained by a metallographic microscope. As shown inFig. 3 , in the salt mixture having the above composition, the solid-liquid coexisting temperature range is as wide as about 60°C, and the temperature dependence of the solid phase ratio is small in the solid phase ratio range of 0 to 40%. Hence, a melt of a salt mixture with an even solid-liquid coexisting state can be obtained easily. In this manner, according to the manufacturing method of this embodiment, theexpendable salt core 2 can be manufactured without strict temperature control or isothermal holding. The range of a temperature where the melt entirely exhibits a solid phase to a temperature where the melt entirely exhibits a liquid phase, in other words, the temperature range where the solid-liquid coexisting state is maintained, changes depending on the composition ratio of the respective components of the salt mixture. - As described above, in the process of cooling the dissolved melt, when the melt temperature reaches the liquidus temperature (melting point) or less, a plurality of solid phase particles are formed and dispersed in the remaining liquid phase. At this time, when stirring the melt in the semi-solidified state, a state can be obtained in which the solid phase is dispersed more evenly in the liquid phase. Note that stirring is not always necessary.
- As an example,
Fig. 4 shows a photograph of a solidification structure obtained by a scanning electron microscope (SEM) when a salt mixture with a composition of 0 mol% of XK+ (= [K+]/([Na+] + [K+]) x 100) and 10 mol% of YCO3 2- (= [CO3 2-]/([CO3 2-] + [Cl-]) x 100) is formed by melting and solidified without stirring. With this composition, primary crystals tend to grow into dendrites, and accordingly stirring is preferred. As another example,Fig. 5 shows an SEM photograph of a solidification structure obtained when a salt mixture with a composition of 0 mol% of XK+ (= [K+]/([Na+] + [K+]) x 100) and 70 mol% of YCO3 2- (= [CO3 2-]/([CO3 2-] + (Cl-]) x 100) is formed by melting and solidified without stirring. With this composition, primary crystals tend to crystallize, and accordingly stirring may not be necessary. - As described above, stirring may be performed although it is not necessary. Stirring can decrease the temperature distribution in the salt mixture in the solid-liquid coexisting state, so that a salt mixture with an even solid phase ratio can be obtained more easily. Also, because stirring can miniaturize and spheroidize solid phase particles in the salt mixture in the solid-liquid coexisting state, the moldability is improved. When molding a core with a high solid phase ratio, stirring is preferred. When mechanical stirring is to be performed, a ceramic stirrer which is resistant to corrosion by a molten salt may be employed.
- When core molding is initiated in the semi-solidified state having the characteristic features as described above, the amount of solidification shrinkage occurring in the solidification process can be suppressed. Thus, a shrinkage cavity, micro-porosity, small heat crack, or the like which is formed in the expendable salt core can be suppressed. As the amount of solidification shrinkage can be suppressed, the expendable salt core can be molded true to the mold more precisely. When casting is initiated in the completely molten state as in the conventional case, the amount of solidification shrinkage is large, so that a shrinkage cavity, micro-porosity, small heat crack, or the like is formed often. The semi-solidification method can suppress these defects, thus improving the strength.
- According to the melting molding method, the amount of solidification shrinkage of the core to be molded is larger than the amount of shrinkage of the metal mold. When molding a cylindrical annular core such a water jacket in a cylinder, a shrinkage cavity, micro-porosity, small heat crack, or the like may be formed in the expendable salt core. Depending on the case, the expendable salt core may be broken in the mold. In contrast to this, as described above, use of a melt in the semi-solidified state can reduce the ratio of solidification shrinkage. As a result, a cylindrical annular core such as a water jacket can be formed.
- In injection molding using a melt, if the melt is injected with an injection force larger than the machine clamp force of the mold, the melt is scattered from the parting surface, i.e., so-called flushing occurs. In contras to this, in injection molding using a melt in a solid-liquid coexisting state, the leading end of the melt solidifies immediately. Even if the melt is injected with an injection force larger than the mold cavity projected area, flushing does not occur. Therefore, during solidification shrinkage of the melt, a large injection pressure can be applied to replenish the melt, so that the shrinkage cavity can be eliminated. When the melt in the solid-liquid coexisting state is employed, casting can be performed at a temperature lower than that required by the completely molten state. This can improve the workability and decrease the heat load to the casting mold.
- Different from metals, salt is not oxidized. Even when stirring described above is performed in the atmosphere, no oxide is caught in the melt. Thus, the melt can be stirred easily for a long period of time. Even when molding an annular shape from a semi-solidified state, no oxide skin is formed on a confluence-junction portion on the opposite side of the melt which separates from the gate into two groups in the circumferential direction. Hence, cold shut does not occur, so that separation at the bonding portion does not occur after molding.
- In order to obtain the solid-liquid coexisting state, the melt is cooled from the molten state to a semi-solidified range, thus achieving the solid-liquid coexisting state. However, the present invention is not limited to this. For example, a salt mixture in the solid phase may be heated to a semi-molten range so that a solid-liquid coexisting state is obtained. A solid powder salt (salt mixture) may be added to a molten salt so that a solid-liquid coexisting state is obtained. Alternatively, a molten salt may be added to a preheated solid salt (salt mixture) so that a solid-liquid coexisting state is obtained.
- In the above description, a case is described in which sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride are mixed such that the molar ratio XK+ (= [K+]/([Na+] + [K+]) x 100) of potassium ions in the entire cations is 33 mol% and that the molar ratio YCO3 2- (= [CO3 2-]/(CO3 2-] + [C1-]) x 100) of carbonate ions in the entire anions is 67 mol%. However, the present invention is not limited to this. For example, when the salt mixture has any one of the compositions shown in the following Tables 1 and 2, casting using a melt in a semi-solidified state is possible. In any case, the salt mixture is formed of only potassium ions, sodium ions, chloride ions, and carbonate ions.
- Table 1 also shows the measurement results (maximum bending loads) of the bending strengths of the fabricated test pieces, and Table 2 also shows the measurement results (maximum bending strengths) of the bending strengths of the fabricated test pieces. Tables 1 and 2 are identical except that representations of the measurement results are different. The state of the bending load and that of the bending strength are shown in
Figs. 6A to 6C andFigs. 7A and 7B in the form of bar graphs. The concentration of each ion is measured according to the analysis method determined by the rules of ion chromatograph analysis of JIS standard K0127. -
Table 1 Sample Number Cation Ratio mol% Anion Ratio mol% Liquidus Temperature °C Molding Temperature °C Bending Load N XNa+ XK+ YCl- YCO3 2- 1st Time 2nd Time 3rd Time 1 67 33 33 67 647 638 2566 2947 2574 2 70 30 40 60 649 632 3229 3192 3274 3 70 30 30 70 665 648 3430 3158 2916 4 60 40 40 60 615 597 3021 2190 2382 5 60 40 30 70 630 619 2150 2662 2606 6 100 0 50 50 675 648 2852 4149 3322 7 100 0 30 70 753 740 3037 2535 3108 8 80 20 50 50 645 625 2526 2566 2350 9 80 20 30 70 704 678 2662 2606 2606 10 70 30 60 40 605 588 2105 3067 3177 11 50 50 30 70 604 592 2566 2347 2268 12 60 40 20 80 652 642 2290 1295 2338 13 90 10 70 30 652 635 2670 818 787 14 75 25 70 30 575 572 2424 2532 1460 15 40 60 40 60 575 565 779 668 904 16 100 0 10 90 827 821 970 1126 1112 17 60 40 10 90 685 671 1474 1533 1630 18 33 67 67 33 648 638 2048 1901 1609 19 40 60 60 40 620 606 1002 1769 1402 20 40 60 70 30 643 630 1426 1763 1410 21 30 70 70 30 655 638 1897 1345 1850 22 30 70 60 40 630 620 1354 657 1096 23 50 50 50 50 590 575 1208 910 1243 24 50 50 80 20 630 622 1394 231 821 25 40 60 80 20 652 644 424 348 625 26 60 40 70 30 602 589 1761 1553 1152 27 20 80 50 50 595 588 1290 1368 1135 -
Table 2 Sample Number Cation Ratio ol% Anion Ratio mol% Liquidus Temperature °C Molding Temperature °C Bending Strength MPa XNa+ XK+ YCl- YCO3 2- 1st Time 2nd Time 3rd Time 1 67 33 33 67 647 638 21.4 24.6 21.4 2 70 30 40 60 649 632 26.9 26.6 27.3 3 70 30 30 70 665 648 28.6 26.3 24.3 4 60 40 40 60 615 597 25.2 18.3 19.9 5 60 40 30 70 630 619 17.9 22.2 21.7 6 100 0 50 50 675 648 23.8 34.6 27.7 7 100 0 30 70 753 740 25.3 21.1 25.9 8 80 20 50 50 645 625 21.0 21.4 19.6 9 80 20 30 70 704 678 22.2 21.7 21.7 10 70 30 60 40 605 588 17.5 25.6 26.5 11 50 50 30 70 604 592 21.4 19.6 18.9 12 60 40 20 80 652 642 19.1 10.8 19.5 13 90 10 70 30 652 635 22.3 6.8 6.6 14 75 25 70 30 575 572 20.2 21.1 12.2 15 40 60 40 60 575 565 6.5 5.6 7.5 16 100 0 10 90 827 821 8.1 9.4 9.3 17 60 40 10 90 685 671 12.3 12.8 13.6 18 33 67 67 33 648 638 17.1 15.8 13.4 19 40 60 60 40 620 606 8.4 14.7 11.7 20 40 60 70 30 643 630 11.9 14.7 11.7 21 30 70 70 30 655 638 15.8 11.2 15.4 22 30 70 60 40 630 620 11.3 5.5 9.1 23 50 50 50 50 590 575 10.1 7.6 10.4 24 50 50 80 20 630 622 11.6 1.9 6.8 25 40 60 80 20 652 644 3.5 2.9 5.2 26 60 40 70 30 602 589 14.7 12.9 9.6 27 20 80 50 50 595 588 10.8 11.4 9.5 -
Fig. 8 shows the relationship (Phase diagram of the Na-K-Cl-CO3 system) among the cationic ratio of potassium ions, the anionic ratio of carbonate ions, and the melting temperature (liquidus temperature).Fig. 8 shows the correspondence between the respective compositions shown in Table 1 and sample numbers.Fig. 8 also shows the liquidus temperature of NaCl when K+ is 0 mol% and CO3 2- is 0 mol%, that of KCl when Na+ is 0 mol% and C03 2- is 0 mol%, that of Na2CO3 when K+ is 0 mol% and Cl- is 0 mol%, and that of K2CO3 when Na+ is 0 mol% and Cl- is 0 mol%. InFig. 8 , thick lines represent eutectic lines. - As is apparent from Tables 1 and 2,
Figs. 6A to 6C ,Fig. 7A ,Fig. 7B , andFig. 8 , the bending test results exhibit high bending strengths in a region where XK+ is 0 to 50 mol% and YCO3 2- is 30 to 80 mol%. Also, the bending test results exhibit particularly high bending strengths in a region where XK+ is 0 to 40 mol% and YCO3 2- is 50 to 70 mol%. - Measurement of the bending strength will be described. To measure the bending strength, a prismatic test piece with a predetermined size is fabricated. A load is applied to the test piece, and the bending load is obtained from the maximum load needed to break the test piece. Fabrication of the test piece will be described first. A rod-
like test piece 901 as shown inFigs. 9A and 9B is formed using a predetermined metal mold. The employed metal mold is made of chrome molybdenum steel, e.g., SCM440H.Fig. 9A also showsriser portions 902 used when charging the metal mold with a melt in a semi-solidified state. In measurement of the bending strength, theportions 902 are cut off.Fig. 9A is a side view, andFig. 9B is a sectional view taken at the position b - b inFig. 9A . The sizes indicated inFigs. 9A and 9B are design values of the metal mold. - To measure the bending strength of the rod-
like test piece 901 fabricated in the above manner, first, as shown inFig. 10 , thetest piece 901 is supported by twosupport portions 1001 arranged at the center of thetest piece 901 at a gap of 50 mm from each other. In this support state, at the intermediate portion of the twosupport portions 1001, twoload portions 1002 at a gap of 10 mm from each other apply a load to thetest piece 901. The load to be applied to thetest piece 901 is gradually increased. The load applied when thetest piece 901 was broken was the bending load shown in Table 1. - A bending strength σ (MPa) can be obtained from a bending load P in accordance with an equation σ = 3LP/BH2 where H is the length of the load direction in the section of the test piece, B is a length perpendicular to the load direction in the section of the test piece, and L is the distance from the
support portions 1001 serving as fulcrums to theload portions 1002 where the load acts. Although thetest piece 901 is formed by pouring the melt in the solid-liquid coexisting state into the metal mold, it is difficult to form a test piece completely free from flow marks or shrinkage cavity and having a shape completely coinciding with the size true to the mold. Therefore, the bending strength is calculated based on an approximation that the test piece has a rectangular section and that H ≈ 20 mm, B ≈ 18 mm, and L = 20 mm. Due to this approximation, the estimated strength is lower than the actual strength by approximately 0% to 20%. For example, it can be assumed that a test piece which is broken by a bending load of 1200N is stronger than an ideal test piece having a bending strength of 10 MPa. - A method of manufacturing another expendable salt core according to the embodiment of the present invention will be described. The following description exemplifies a case in which a mold (metal mold) is charged with a melt under a pressure to manufacture an expendable salt core 2 (die casting). As the crucible, a close-packed alumina crucible made of the same material as that of a Tamman tube is employed. A predetermined amount of salt mixture consisting of sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride is put in the crucible, the crucible is placed in a heating furnace, and the temperature is raised. For the purpose of protection of the crucible, the temperature is raised gradually to reach the target temperature in about 14 hours.
- The target temperature is set at a value higher than the liquidus temperature corresponding to the molar ratio of the salt mixture by 10 to 30°C. Once the temperature reaches the target temperature, it is held at the target temperature. The temperatures of the metal mold and injection sleeve are set to approximately 180 to 220°C. As the metal mold, one that can be heated to a mold temperature of about 250°C is preferable. Also, a metal mold is preferred the casting cavity of which can be eliminated by applying a casting injection pressure of as high as about 120 MPa at maximum.
- Subsequently, the melt of the salt mixture which is molten in the crucible is dipped up with a dipper. Prior to dipping up, the dipper must be heated to about 500 to 600°C by a heating means such as a burner. As soon as the melt in the crucible is dipped up with the dipper, it is started to be gradually deprived of heat by the dipper. Thus, the temperature of the melt decreases to be lower than the liquidus temperature, thus providing the solid-liquid coexisting state. During dipping up, the melt is stirred as it is shaken in the moving dipper, and primary crystals are deposited to form particles. In this manner, during the process of transporting the melt from the crucible and pouring it into the injection sleeve, the melt of the salt mixture in the dipper is set in the solid-liquid coexisting state.
- When pouring the melt of the salt mixture in the semi-solidified state into the injection sleeve in this manner, the semi-solidified state progresses in the sleeve as well. Subsequently, the melt is injected into the cavity under a high pressure. After charging with the melt, the casting pressure is continuously applied into the mold. For example, a pressure of 120 MPa in the pressure ratio of a hydraulic cylinder which advances the plunger is applied into the mold. In this process, the plunger is advanced to replenish solidification shrinkage that takes place during solidification, thus continuously applying the pressure of 120 MPa. The solidification time is about 65 to 75 sec. In the solidification process, the plunger is continuously moved forward as long as solidification shrinkage can be replenished, thus continuously applying the pressure of 120 MPa.
- After charging the mold with the melt under the pressure and solidifying the melt in the above manner, the solidified expendable salt core is taken out from the mold. A push pin and return pin may be placed in the stationary mold so that when the mold is opened, the obtained salt core is released from the stationary mold well. The taken-out expendable salt core may be gradually cooled, and the cooled expendable salt core may be put in a dried container.
- An example will be described regarding the manufacturing conditions and strength measurement result of the expendable salt core which is manufactured by injecting into a metal mold under a high pressure a melt of a salt mixture in a semi-solidified state in which the solid phase and liquid phase coexist.
- The conditions are as follows.
- (1) The test piece subjected to strength measurement had an almost rectangular solid shape in the same manner as in
Figs. 9A and 9B . - (2) The melt was fabricated by mixing sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride and melting them. The resultant melt was adjusted such that the molar ratio XK+ (= [K+]/([Na+] + [K+]) x 100) of potassium ions in the entire cations was 30 mol% and that a molar ratio YCO3 2- (= [CO3 2]/([CO3 2-] + [Cl-]) x 100) of carbonate ions in the entire anions was 54 mol%.
- (3) The liquidus temperature of the salt mixture is 630°C.
- (4) The salt mixture contained in the crucible was dissolved by gradually raising the temperature to exceed the liquidus temperature of 630°C in 14 hours. Then, the dissolved melt was held at 640 to 660°C. The temperature was controlled automatically.
- (5) The dipper was heated to 500 to 600°C.
- (6) The melt was dipped up with the dipper and cooled in the dipper to 630°C or less, so that the melt was set in the semi-solidified state.
- (7) The sleeve temperature and metal mold temperature were 180 to 220°C.
- (8) When the temperature of the melt of the salt mixture was 620°C in the injection sleeve, the melt was injected into the metal mold under a high pressure as indicated by an injection curve to be described later. When the temperature of the melt of the mixture salt is 620°C, the melt is in the semi-solidified state in which the solid and liquid coexist.
- To measure the pressure in the cavity, the pressures acting on the push pins provided to two portions, i.e., a gate portion 1101 shown in
Fig. 11 and a portion 1102 inside the mold, were measured. The measured pressures were both about 60 MPa, as represented by the injection curves inFig. 12 . InFig. 12 , the solid line represents the measurement result obtained at the portion 1101, and the dashed line represents the measurement result obtained at the portion 1102. Since the injection start time point until immediately before (by about 5 sec) the solidification end point when the mold was opened, the pressures to be measured were about 60 MPa, thus maintained almost the same state. Then, at the mold opening time point, the pressures sharply decreased. Actually, the pressures to be measured gradually decrease, as shown inFig. 12 . This may be because the expendable salt core solidifies starting with its surface to interfere with the pressure from being transmitted well. A directional solidification state was exhibited in which the pressure inside the mold dropped prior to the pressure at the gate portion. As described above, the pressure of about 120 MPa was applied to the plunger. Part of the melt solidified into gel in the injection sleeve interfered with driving of the plunger. Accordingly, the pressure actually acting on the melt in the cavity was approximately 60 MPa. - In die casting of a metal such as aluminum, the melt has high thermal conductivity and requires a short solidification time. Hence, that portion of the melt which is located at the intermediate portion of the mold often solidifies before that portion of the melt which is located at the distal end of the mold. Then, the distal end of the mold may not be sufficiently replenished with the melt. In contrast to this, a molten salt has low thermal conductivity and requires a solidification time about three times that of aluminum. Accordingly, as shown in
Fig. 12 , an almost constant pressure can be continuously applied to the entire cavity until mold opening. In this manner, to apply a pressure evenly to the cavity until opening the mold, e.g., to always apply the same pressure to the cavity until mold opening or gradually change the pressure to apply to the cavity with the same change amount until mold opening, is the condition necessary to obtain a high strength. - Test pieces manufactured as described above were subjected to bending strength measurement in the same manner as described above. A high strength exceeding 40 MPa was obtained as shown in the following Tables 3 and 4. In general, a bending strength of about 20 to 37 MPa is obtained by a widely employed expendable salt core which is manufactured by sintering after press molding (reference 4:
US3,963,818 ). According to this embodiment, a higher bending strength is obtained. With an expendable salt core which is manufactured by sintering after press molding, a complicated shape such as a water jacket cannot be formed. According to this embodiment, however, an expendable salt core with a complicated shape can be manufactured easily. As the expendable salt core of this embodiment is formed by solidifying a molten salt, the surface state of the expendable salt core reflects the surface state of the metal mold, so that a smooth surface can be obtained. Therefore, in a cast product using the expendable salt core according to this embodiment, a portion which is in contact with the expendable salt core is formed to be highly smooth. -
Table 3 Sample Number Cation Ratio mol% Anion Ratio mol% Liquidus Temperature °C Molding Temperature °C Bending Load N XNa+ XK+ YCl- YCO3 2- 1st Time 2nd Time 3rd Time 28 70 30 67 54 630 620 4812 5251 5008 -
Table 4 Sample Number Cation Ratio mol% Anion Ratio mol% Liquidus Temperature °C Molding Temperature °C Bending Strength MPa XNa+ XK+ YCl- YCO3 2- 1st Time 2nd Time 3rd Time 28 70 30 67 54 630 620 40.1 43.8 41.7 - Although a salt mixture of sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride is used in the above description, the present invention is not limited to this. For example, potassium carbonate, sodium chloride, and potassium chloride may be mixed, or sodium carbonate, sodium chloride, and potassium chloride may be mixed. Alternatively, other salts such as sodium bromide, potassium bromide, sodium iodide, potassium iodide, calcium chloride, potassium nitrate, sodium nitrate, potassium sulfate, lithium sulfate, magnesium sulfate, sodium sulfate, barium carbonate, and calcium carbonate may be mixed. A reinforcing ceramic material or another reinforcing agent may be contained in the mixture.
- Another example of how an expendable salt core for casting according to the embodiment of the present invention is used will be described with reference to
Figs. 13 and14 .Fig. 13 is a partially cutaway perspective view of a cylinder block which is cast using an expendable salt core for casting according to the present invention. Referring toFig. 13 ,reference numeral 1301 denotes an engine cylinder block which is made of an aluminum alloy and cast using anexpendable salt core 1302 as an expendable salt core for casting according to the present invention. Theexpendable salt core 1302 is manufactured in the same manner as theexpendable salt core 2 shown inFig. 1 . Thecylinder block 1301 is part of a water cooling 4-cycle 1-cylinder engine for a motorcycle which is molded into a predetermined shape by die casting. - The
cylinder block 1301 shown inFig. 13 comprises acylinder bore 1303 and acylinder body 1304 having thecylinder bore 1303. Although not shown, a crank case is attached to the lower portion of thecylinder body 1304 and rotatably, axially supports a crank shaft through a bearing. - The
cylinder body 1304 is a so-called closed-deck-type cylinder body, and has awater jacket 1306 which is formed in it using theexpendable salt core 1302. Thewater jacket 1306 is formed to include a cooling water passage forming portion (not shown), a cooling water inlet port (not shown), a maincooling water passage 1309, and acommunication passage 1310. The cooling water passage forming portion projects on one side of thecylinder body 1304. The cooling water inlet port is formed in the cooling water passage forming portion. The maincooling water passage 1309 is formed to communicate with a cooling water supply passage (not shown) formed in the cooling water passage forming portion and cover thecylinder bore 1303. Thecommunication passage 1310 extends upward inFig. 13 from the maincooling water passage 1309 and opens to amating surface 1304a with respect to a cylinder head (not shown) at the upper end of thecylinder body 1304. - The
water jacket 1306 described above supplies cooling water flowing in from the cooling water inlet port (not shown) to the maincooling water passage 1309 around the cylinder bore through the cooling water supply passage, and guides the cooling water from the maincooling water passage 1309 to a cooling water passage in the cylinder head (not shown) through thecommunication passage 1310. Since thewater jacket 1306 is formed in this manner, thecylinder body 1304 is covered with the ceiling wall (the wall that forms themating surface 1304a) of thecylinder body 1304 except that thecommunication passage 1310 of thewater jacket 1306 opens to themating surface 1304a at the upper end to which the cylinder head is connected. Hence, a closed-deck-type arrangement is formed. - The
expendable salt core 1302 to form thewater jacket 1306 has a shape identical to that obtained by integrally connecting the respective portions of thewater jacket 1306, as shown in the photograph ofFig. 14 as well. InFig. 13 , thecylinder body 1304 is partly cut away to facilitate understanding of the shape of the expendable salt core 1302 (the shape of the water jacket 1306). Note thatreference numeral 1311 denotes a passage for a cam shaft driving chain; and 1312, a chain tensioner attaching hole. - The
expendable salt core 1302 shown inFig. 13 (Fig. 14 ) is formed using a plurality of types of salts such as sodium carbonate, sodium chloride, and potassium chloride by, e.g., die casting in a solid-liquid coexisting state such as a semi-solidified state into the shape of thewater jacket 1306, in the same manner as theexpendable salt core 2 described above. Note that theexpendable salt core 1302 can be formed by a casting method other than die casting, e.g., gravity casting. In formation of theexpendable salt core 1302 which employs die casting, first, a mixture consisting of a plurality of salts (to be described later) is melted by heating to obtain a melt. Then, the temperature of the melt is decreased to set the melt in a semi-solidified (solid-liquid coexisting) state. The melt in the semi-solidified state is injected into a metal mold for an expendable salt core under a high pressure and solidified. After solidification, the obtained expendable salt core is taken out from the metal mold. - As shown in
Fig. 13 , in theexpendable salt core 1302, the cooling water passage forming portion (not shown) which forms the cooling water inlet port and cooling water supply passage, anannular portion 1302b which surrounds thecylinder bore 1303, and a plurality ofprojections 1302a extending upward from theannular portion 1302b are formed integrally. Theprojections 1302a form thecommunication passage 1310 of thewater jacket 1306. As is conventionally known, theexpendable salt core 1302 is supported at a predetermined position in the metal mold (not shown) by a core print (not shown inFig. 13 ) during casting, and is removed by dissolution with hot water or vapor after casting. - To remove the
expendable salt core 1302 after casting, thecylinder block 1301 may be dipped in a dissolution tank (not shown) which contains dissolving liquid consisting of hydrochloric acid, hot water, and the like. When dipping thecylinder block 1301 in the dissolving liquid, the cooling water inlet port of the cooling water passage forming portion (not shown) and theprojections 1302a exposed to themating surface 1304a, of theexpendable salt core 1302 come into contact with the dissolving liquid and dissolve. The dissolved portions expand gradually until all the portions dissolve finally. In this core removing process, to promote dissolution of theexpendable salt core 1302 left in thewater jacket 1306, hot water or vapor may be sprayed under a pressure from a hole. In theexpendable salt core 1302, in place of theprojections 1302a, a core print may be inserted in portions where theprojections 1302a are to be formed. - As described above, according to the present invention, the annular
expendable salt core 1302 can be formed easily. Note that the region of the core print shown in the photograph ofFig. 14 is a region that projects upward from themating surface 1304a ofFig. 13 . Although the overflow, gate, runner, and biscuit portions shown in the photograph ofFig. 14 remain when casting theexpendable salt core 1302, they are removed when using theexpendable salt core 1302 for casting thecylinder block 1301. - The present invention can be suitably used as a core in casting such as aluminum die casting.
Claims (13)
- A method of manufacturing an expendable salt core for casting, characterized by comprising at least:a first step of heating a salt mixture containing at least a potassium salt and a sodium salt to form a melt in a solid-liquid coexisting state in which a solid phase and a liquid phase coexist;a second step of charging said melt in the solid-liquid coexisting state into a core mold; anda third step of solidifying said melt in said mold to mold an expendable salt core for casting.
- A method of manufacturing an expendable salt core for casting according to claim 1, characterized in that
in said first step, said salt mixture is heated to be set in a liquid-phase-only state, and thereafter said salt mixture is cooled, thus forming said melt in the solid-liquid coexisting state. - A method of manufacturing an expendable salt core for casting according to claim 1, characterized in that
in said second step and said third step, said mold is charged with said melt under a pressure and said melt is solidified. - A method of manufacturing an expendable salt core for casting according to claim 3, characterized in that
said pressure is applied evenly until said mold is opened. - A method of manufacturing an expendable salt core for casting according to claim 1, characterized in that
said salt mixture is formed of only potassium ions, sodium ions, chloride ions, and carbonate ions, and
a molar ratio of said potassium ions in all the cations is 50 mol% at maximum and a molar ratio of carbonate ions in all the anions is 30 to 80 mol%. - A method of manufacturing an expendable salt core for casting according to claim 5, characterized in that
in said salt mixture, the molar ratio of the potassium ions in all the cations is 40 mol% at maximum and the molar ratio of carbonate ions in all the anions is 50 to 70 mol%. - An expendable salt core for casting, characterized by
being molded by heating a salt mixture containing at least a potassium salt and a sodium salt to form a melt in a solid-liquid coexisting state in which a solid phase and a liquid phase coexist, charging said melt in the solid-liquid coexisting state into a core mold, and solidifying said melt in said mold. - An expendable salt core for casting according to claim 7, characterized in that
said melt in the solid-liquid coexisting state is formed by heating said salt mixture to be set in a liquid-phase-only state, and thereafter cooling said salt mixture. - An expendable salt core for casting according to claim 7, characterized in that
said expendable salt core for casting is formed by charging said mold with said melt under a pressure and solidifying said melt. - An expendable salt core for casting according to claim 9, characterized in that
said pressure is applied evenly until said mold is opened. - An expendable salt core for casting according to claim 7, characterized in that
said salt mixture is formed of only potassium ions, sodium ions, chloride ions, and carbonate ions, and
a molar ratio of the potassium ions in all cations is 50 mol% at maximum and a molar ratio of carbonate ions in all the anions is 30 to 80 mol%. - An expendable salt core for casting according to claim 11, characterized in that
in said salt mixture, the molar ratio of the potassium ions in all the anions is 40 mol% at maximum and the molar ratio of carbonate ions in all the cations is 50 to 70 mol%. - An expendable salt core for casting according to claim 7, characterized in that
said expendable salt core for casting comprises a core to mold a water jacket for water cooling of a closed-deck type cylinder block of engine.
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JP2006138879 | 2006-05-18 | ||
PCT/JP2007/060239 WO2007135995A1 (en) | 2006-05-18 | 2007-05-18 | Method for producing salt core for casting and salt core for casting |
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---|---|---|---|
EP07743674A Withdrawn EP2022577A4 (en) | 2006-05-18 | 2007-05-18 | Method for producing salt core for casting and salt core for casting |
Country Status (4)
Country | Link |
---|---|
US (1) | US20090205801A1 (en) |
EP (1) | EP2022577A4 (en) |
JP (1) | JP4685933B2 (en) |
WO (1) | WO2007135995A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110062624A1 (en) * | 2008-05-09 | 2011-03-17 | Yamaha Hatsudoki Kabushiki Kaisha | Method of manufacturing expendable salt core for casting |
EP2586546A1 (en) * | 2011-10-31 | 2013-05-01 | Bühler AG | Method for preparing salt cores |
DE102012022390B3 (en) * | 2012-11-15 | 2014-04-03 | Audi Ag | Preparing a salt core for the formation of cavities in a light-metal die-casting, comprises introducing a paste-like salt-liquid mixture into cavity of compression mold, and compressing the mixture to expel fluid contained in the mixture |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5419549B2 (en) * | 2009-05-01 | 2014-02-19 | ビューラー・アクチエンゲゼルシャフト | Manufacturing method of salt core for casting |
EP2647451A1 (en) | 2012-04-04 | 2013-10-09 | Bühler AG | Method for manufacturing salt cores |
ITMI20120950A1 (en) | 2012-06-01 | 2013-12-02 | Flavio Mancini | METHOD AND PLANT TO OBTAIN DIE-CASTING JETS IN LIGHT ALLOYS WITH NON-METALLIC SOURCES |
KR101637638B1 (en) * | 2014-02-18 | 2016-07-07 | 현대자동차주식회사 | Casting product and manufacturing method thereof |
CN108237206A (en) * | 2018-02-28 | 2018-07-03 | 厦门格欧博新材料科技有限公司 | A kind of salt core former |
KR102176149B1 (en) * | 2018-12-04 | 2020-11-09 | 한국생산기술연구원 | Method for manufacturing a hollow wheel having a hollow structure by using a melt type core |
CN114951556A (en) * | 2022-05-31 | 2022-08-30 | 西北橡胶塑料研究设计院有限公司 | Preparation method of low-cost water-soluble core material for compression molding process |
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US5303761A (en) * | 1993-03-05 | 1994-04-19 | Puget Corporation | Die casting using casting salt cores |
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JPS5210803B1 (en) * | 1968-01-20 | 1977-03-26 | ||
JPS4839696B1 (en) * | 1969-12-27 | 1973-11-26 | ||
JPS4839696A (en) | 1971-09-27 | 1973-06-11 | ||
US3963818A (en) | 1971-10-29 | 1976-06-15 | Toyo Kogyo Co., Ltd. | Water soluble core for pressure die casting and process for making the same |
JPS5210803A (en) | 1975-07-12 | 1977-01-27 | Inst Gorunogo Dera Akademii Na | Device for retaining shank of cold chisel |
JPS5314618A (en) * | 1976-07-28 | 1978-02-09 | Hitachi Ltd | Water soluble casting mould |
US4446906A (en) * | 1980-11-13 | 1984-05-08 | Ford Motor Company | Method of making a cast aluminum based engine block |
US4840219A (en) * | 1988-03-28 | 1989-06-20 | Foreman Robert W | Mixture and method for preparing casting cores and cores prepared thereby |
JPH0815647B2 (en) * | 1990-06-28 | 1996-02-21 | 宇部興産株式会社 | Engine block casting equipment |
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2007
- 2007-05-18 JP JP2008516667A patent/JP4685933B2/en not_active Expired - Fee Related
- 2007-05-18 WO PCT/JP2007/060239 patent/WO2007135995A1/en active Application Filing
- 2007-05-18 EP EP07743674A patent/EP2022577A4/en not_active Withdrawn
- 2007-05-18 US US12/301,073 patent/US20090205801A1/en not_active Abandoned
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JPS50136225A (en) * | 1974-04-19 | 1975-10-29 | ||
US4694881A (en) * | 1981-12-01 | 1987-09-22 | The Dow Chemical Company | Method for making thixotropic materials |
US5303761A (en) * | 1993-03-05 | 1994-04-19 | Puget Corporation | Die casting using casting salt cores |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110062624A1 (en) * | 2008-05-09 | 2011-03-17 | Yamaha Hatsudoki Kabushiki Kaisha | Method of manufacturing expendable salt core for casting |
EP2277644A4 (en) * | 2008-05-09 | 2013-07-10 | Yamaha Motor Co Ltd | Process for producing salt core for casting |
US8574476B2 (en) | 2008-05-09 | 2013-11-05 | Buhler Ag | Method of manufacturing expendable salt core for casting |
EP2586546A1 (en) * | 2011-10-31 | 2013-05-01 | Bühler AG | Method for preparing salt cores |
WO2013064304A1 (en) * | 2011-10-31 | 2013-05-10 | Bühler AG | Method for producing salt cores |
DE102012022390B3 (en) * | 2012-11-15 | 2014-04-03 | Audi Ag | Preparing a salt core for the formation of cavities in a light-metal die-casting, comprises introducing a paste-like salt-liquid mixture into cavity of compression mold, and compressing the mixture to expel fluid contained in the mixture |
Also Published As
Publication number | Publication date |
---|---|
JPWO2007135995A1 (en) | 2009-10-01 |
EP2022577A4 (en) | 2013-03-20 |
WO2007135995A1 (en) | 2007-11-29 |
US20090205801A1 (en) | 2009-08-20 |
JP4685933B2 (en) | 2011-05-18 |
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