Method for manufacturing core and method for casting casting

Abstract

The present invention provides a core manufacturing method and a casting method of a casting, which can suppress the occurrence of protrusion or defect in a female thread part when casting a casting having a threaded hole in which the female thread part is formed. A method for manufacturing a core having a head part and a shaft part in which a male thread part is formed, the method comprising: a step for micronizing a powder containing a salt until the average particle diameter becomes submicron or less; filling powder into a mold provided with a first cavity in which the head part is molded and a second cavity in which the shaft part is molded; and pressurizing the powder through the mold.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a core and a method for casting a casting. Background Technology

[0002] Patent document 1 discloses a method for casting liquid-cooled radiators using a water-soluble core, wherein the water-soluble core is a salt core composed of water-soluble substances such as sodium chloride, and the water-soluble core is formed by compacting granular sodium hydroxide using a mold.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-167274 Summary of the Invention

[0004] When using salt cores or sand cores to cast parts with threaded holes forming internal threads, the large particle size of the salt or sand in the core causes molten metal to enter between the particles and solidify, sometimes resulting in protrusions or defects in the internal threads. In this case, if the inner diameter of the threaded hole is small, the protrusions or defects in the internal threads may prevent the bolt from engaging with the threaded hole.

[0005] In order to solve this problem, the present invention provides a manufacturing method for suppressing the formation of protrusions or defects in the internal thread portion of a core when casting a casting having a threaded hole with an internal thread portion, and a casting method for the casting.

[0006] The present invention discloses a method for manufacturing a core having a head and a shaft having an external thread. The method comprises the following steps: micronizing a salt-containing powder until the average particle size becomes submicron or less; filling the powder into a mold having a first cavity for forming the head and a second cavity for forming the shaft; and pressurizing the powder through the mold.

[0007] With this structure, when casting a part having a threaded hole with an internal thread, if a core manufactured by the core manufacturing method of the present invention is used, it is possible to suppress the occurrence of protrusions or defects in the internal thread.

[0008] The method for manufacturing the core includes: a mortar having an upper mortar and a lower mortar, wherein grooves with a depth and width of less than submicron are formed on the lower surface of the upper mortar and the upper surface of the lower mortar; and a step of refining the powder can be a step of feeding the powder between the upper mortar and the lower mortar and rotating the upper mortar. With this structure, the average particle size of the powder can be easily refined to less than submicron.

[0009] The casting method of the present invention includes the following steps: placing a core manufactured by the core manufacturing method of the present invention into a mold; injecting molten metal into the cavity of the mold; cooling and solidifying the molten metal; and removing the core from the casting.

[0010] This structure helps to prevent protrusions or defects from forming in the internal thread.

[0011] Invention Effects

[0012] This invention provides a manufacturing method for suppressing the formation of protrusions or defects in the internal thread portion of a core when casting a casting having a threaded hole with an internal thread portion, and a casting method for the casting. Attached Figure Description

[0013] Figure 1 This is a schematic perspective view of the core manufactured in this embodiment.

[0014] Figure 2 This is a schematic structural diagram of the mortar used in the core manufacturing method according to this embodiment.

[0015] Figure 3 yes Figure 2 The diagram shows a schematic bottom view of the upper mortar.

[0016] Figure 4 yes Figure 2 The mortar shown is a schematic partial cross-sectional view of the grinding part.

[0017] Figure 5 This is a schematic structural diagram of the mold used in the core manufacturing method according to this embodiment.

[0018] Figure 6 This is a schematic structural diagram of a mold used to cast castings using a core manufactured in this embodiment. Detailed Implementation

[0019] The following uses Figures 1-6 The embodiments of the present invention will be described. Figure 1 This is a schematic perspective view of the core manufactured in this embodiment. Figure 2 This is a schematic structural diagram of the mortar used in the core manufacturing method according to this embodiment. Figure 3 yes Figure 2 The diagram shows a schematic bottom view of the upper mortar. Figure 4 yes Figure 2 The mortar shown is a schematic partial cross-sectional view of the grinding part. Figure 5 This is a schematic structural diagram of the mold used in the core manufacturing method according to this embodiment. Figure 6This is a schematic structural diagram of a mold used to cast castings using a core manufactured in this embodiment.

[0020] [Core Description]

[0021] refer to Figure 1 The core 1 manufactured in this embodiment will be described. The core 1 manufactured in this embodiment is a core 1 for casting a casting having a threaded hole with an internal thread portion, and is a core 1 for forming the threaded hole portion.

[0022] like Figure 1 As shown, the core 1 is in the shape of a hexagonal bolt and has a head 2 and a shaft 3. The head 2 is hexagonal when viewed axially. An external thread 4 is formed on the shaft 3. The external thread 4 is integrally formed from one end of the shaft 3 that engages with the head 2 to the other end of the shaft 3 that has a front end portion.

[0023] Core 1 is formed using salt as a raw material. The salt used as a raw material can be sodium chloride, potassium chloride, magnesium chloride, or a mixture thereof. It can also be a salt containing bromide or carbonate ions. Furthermore, inorganic materials such as quartz, or phenolic resin, can be added as a binder.

[0024] [Explanation of the manufacturing method for the core]

[0025] Next, refer to Figures 2-5 The manufacturing method of the core 1 according to this embodiment will be described. The manufacturing method of the core 1 includes: a step of micronizing powder; a step of filling the powder into a mold; and a step of pressurizing the powder.

[0026] The process of refining powder is explained.

[0027] The salt used as the raw material for core 1 was prepared as sodium chloride powder with a purity of 99.0% or higher and an average particle size of 0.4 mm.

[0028] Next, in order to refine the sodium chloride powder, a process was prepared. Figure 2 The mortar 10 shown has an upper mortar 11 and a lower mortar 15. The upper mortar 11 is positioned relative to the lower mortar 15 in the direction of gravity. Figure 2 The upper side (in the Z direction). A handle 25 is installed on the outer periphery of the upper mortar 11. By turning the handle 25, the upper mortar 11 rotates via the bearing 21 located at the center of the shaft of the mortar 10.

[0029] A supply hole 19 for adding sodium chloride powder is provided on the upper mortar 11. A receiving portion 20 is provided between the upper mortar 11 and the lower mortar 15, near the bearing 21. The receiving portion 20 is formed by a gap between the lower surface 12 of the upper mortar 11 and the upper surface 16 of the lower mortar 15, and the gap decreases from the axial center of the mortar 10 towards the outer periphery. The receiving portion 20 communicates with the supply hole 19. A grinding portion 22 is provided on the outside of the receiving portion 20, in which the lower surface 12 of the upper mortar 11 contacts the upper surface 16 of the lower mortar 15.

[0030] The mortar 10 is formed of a superhard material. Examples of superhard materials include WC-Co alloys, WC-TiC-Co alloys, WC-TaC-Co alloys, WC-TiC-TaC-Co alloys, and WC-Ni alloys. Alternatively, the mortar 10 does not need to be made entirely of a superhard material; a superhard material can be used to cover the lower surface 12 of the upper mortar 11 and the upper surface 16 of the lower mortar 15.

[0031] like Figure 3 , Figure 4 As shown, a plurality of grooves 13 and 14 are formed on the lower surface 12 of the upper socket 11. The grooves 13 and 14 are composed of a plurality of grooves 13 extending radially from the axial center of the upper socket 11 and a plurality of grooves 14 branching from the grooves 13 and extending outwards. Figure 4 As shown, the cross-sections of grooves 13 and 14 are roughly U-shaped.

[0032] like Figure 4 As shown, grooves 17 and 18 are formed on the upper surface 16 of the lower socket 15. Although not shown, grooves 17 and 18, like grooves 13 and 14, are composed of a plurality of grooves 17 extending radially from the axial center of the lower socket 15 and a plurality of grooves 18 branching from the grooves 17 and extending outwards. The cross-sections of grooves 17 and 18 are generally V-shaped.

[0033] The depth and width of grooves 13, 14, 17, and 18 are formed to be below submicron (below 1 μm), preferably around 0.5 μm. To achieve this submicron depth and width, femtosecond laser processing or similar methods are used. By setting the depth and width of grooves 13, 14, 17, and 18 to below submicron, the average particle size of the sodium chloride powder 5 can be refined to below submicron.

[0034] After preparing sodium chloride powder 5 and mortar 10, sodium chloride powder is fed into the supply hole 19, and the handle 25 is turned to rotate the upper mortar 11. The sodium chloride powder entering the receiving part 20 from the supply hole 19 is ground to the size of the gap in the receiving part 20 by the rotation of the upper mortar 11.

[0035] Sodium chloride powder in the receiving section 20 is moved to the grinding section 22 outside the receiving section 20 by the rotation of the upper mortar 11. For example... Figure 4 As shown, in the grinding section 22, sodium chloride powder 5 partially enters the grooves 17 and 18, and the portion protruding from the grooves 17 and 18 is sheared by the lower surface 12 of the upper mortar 11. In this way, the sodium chloride powder is refined to form sodium chloride powder with an average particle size of submicron or less.

[0036] Next, the process of filling the mold with powder will be explained.

[0037] like Figure 5 As shown, a mold 30 filled with finely powdered sodium chloride is prepared. The mold 30 has a die 31, an upper punch 32, and a lower punch 33. The die 31 is generally cylindrical and configured such that its central axis is along the direction of gravity (…). Figure 5 (Extending in the Z direction). An upper punch 32 is fitted on the upper side of the die 31, and a lower punch 33 is fitted on the lower side of the die 31.

[0038] A first cavity 35 is formed between the lower surface of the upper punch 32 and the upper surface of the lower punch 33. Figure 5 (The area shown is higher than the single-dot line). The first cavity 35 is shaped like the head 2 to form the head 2 of the core 1. In order to make the head 2 of the core 1 hexagonal when viewed axially, the inner periphery of the die 31 is formed into a hexagon when viewed axially.

[0039] A generally cylindrical cylindrical portion 33a is provided on the upper side of the lower punch 33, and a second cavity 36 is formed inside the cylindrical portion 33a. Figure 5 (The area shown is lower than the single-dot dashed line). The second cavity 36 is shaped like a shaft 3 for forming the shaft portion 3 of the core 1. A thread for forming the external thread portion 4 formed on the shaft portion 3 is provided on the inner circumference of the cylindrical portion 33a. The first cavity 35 is connected to the second cavity 36.

[0040] After preparing the mold 30, remove the upper punch 32 from the mold 30 and fill the first cavity 35 and the second cavity 36 with finely ground sodium chloride powder.

[0041] Next, the process of pressurizing the powder will be explained.

[0042] After filling the mold 30 with finely powdered sodium chloride, the upper punch 32 is fitted into the die 31. Then, a predetermined pressure is applied to the upper punch 32 from above using a press (not shown). In this way, the sodium chloride powder filled in the mold 30 is pressurized. The pressure applied can be, for example, 10 MPa to 5000 MPa.

[0043] After pressurizing the sodium chloride powder for a specified time, the upper punch 32 and lower punch 33 are removed from the mold 30, yielding... Figure 1 Core 1 is shown.

[0044] [Explanation of casting method]

[0045] Next, refer to Figure 6 The method for casting a part using the core 1 manufactured in this embodiment will be described. The cast part is a regular dodecahedron, and threaded holes with internal threads are provided on all faces of the regular dodecahedron.

[0046] The casting method includes the steps of placing a core in a mold, injecting molten metal into the cavity of the mold, cooling and solidifying the molten metal, and removing the core from the casting.

[0047] The process of placing the core into the mold is explained.

[0048] In order to cast a regular dodecahedron, preparations were made Figure 6 The mold 50 shown is a mold made of hot work tool steel or the like. A cavity 51 is formed inside the mold 50, and the cavity 51 is in the shape of a regular dodecahedron. Twelve faces 52 are provided around the periphery of the cavity 51, and the core 1 is disposed on all faces 52. The front end of the shaft portion 3 of the core 1 is disposed in the cavity 51, and the head portion 3 and the head 2 are disposed on the outside of the cavity 51.

[0049] Next, the process of injecting molten metal into the cavity of the mold will be explained.

[0050] Molten aluminum is poured into cavity 51 through a gate not shown in the diagram. The molten metal is poured into cavity 51 while a specified pressure is applied. The melting point of aluminum (660°C) is lower than that of sodium chloride (1470°C), which constitutes core 1, so core 1 will not collapse during casting. The molten metal is not limited to aluminum; any metal with a melting point lower than that of sodium chloride (1470°C) can be used, such as tin (melting point 232°C), copper (melting point 1085°C), magnesium (melting point 650°C), zinc (melting point 419°C), etc.

[0051] Next, the process of cooling the molten metal to solidify it and removing the core from the casting will be explained.

[0052] After molten metal is poured into the cavity 51, it is cooled for a predetermined time to solidify. Once solidified, the core 1 is rotated and removed from the casting. Alternatively, since sodium chloride is water-soluble, the core 1 can also be removed by dissolving it in water. After removing the core 1, the mold 50 is opened. Thus, a dodecahedral casting with threaded holes having internal threads formed on all faces is obtained. Furthermore, the removed core 1 can be crushed and reused.

[0053] The core 1 manufactured by the core manufacturing method of the present invention is formed from sodium chloride powder with an average particle size refined to submicron or less. Since the average particle size is submicron or less, there are almost no gaps between the particles of sodium chloride powder.

[0054] Therefore, when casting a part having a threaded hole with an internal thread, if the threaded hole is formed using a core 1 manufactured by the core manufacturing method of the present invention, the molten metal will not enter between the particles of sodium chloride powder and solidify, thus suppressing the formation of protrusions or defects in the internal thread. Therefore, even if the inner diameter of the threaded hole in the cast part is small, the bolt can be screwed into the threaded hole because the formation of protrusions or defects in the internal thread is suppressed.

[0055] Furthermore, by using a stone mortar with grooves of submicron depth and width formed on the lower surface of the upper mortar and the upper surface of the lower mortar, the average particle size of sodium chloride powder can be easily refined to submicron.

[0056] Furthermore, the present invention is not limited to the above-described embodiments and can be appropriately modified without departing from the spirit of the invention.

[0057] Symbol Explanation

[0058] 1-Core, 2-Head, 3-Shaft, 4-External thread, 5-Sodium chloride powder, 10-Groove, 11-Upper mortar, 15-Lower mortar, 13, 14, 17, 18-Groove, 30-Mold, 35-First cavity, 36-Second cavity, 50-Casting mold.

Claims

1. A method for manufacturing a core, the core having a head and a shaft portion having an external thread, the method for manufacturing the core being characterized by comprising the following steps: The salt-containing powder is refined until the average particle size becomes submicron. The powder is filled into a mold having a first cavity for forming the head and a second cavity for forming the shaft; and The powder is pressurized using the mold.

2. The method for manufacturing a core according to claim 1, characterized in that, have: A stone mortar, which has an upper mortar and a lower mortar, The mortar has grooves with a depth and width of less than submicrometer formed on the lower surface of the upper mortar and the upper surface of the lower mortar. The process of micronizing the powder involves feeding the powder between the upper and lower mortars and rotating the upper mortar.

3. A casting method for a casting having a threaded hole with an internal thread, the casting method being characterized by comprising the following steps: The core manufactured by the core manufacturing method according to claim 1 or 2 is placed in the mold; Molten metal is injected into the cavity of the mold; and The molten metal is cooled and solidified, and the core is removed from the casting.

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