CN107931535B - Core bar of volute casing casting sand core and manufacturing method thereof - Google Patents
Core bar of volute casing casting sand core and manufacturing method thereof Download PDFInfo
- Publication number
- CN107931535B CN107931535B CN201711202627.5A CN201711202627A CN107931535B CN 107931535 B CN107931535 B CN 107931535B CN 201711202627 A CN201711202627 A CN 201711202627A CN 107931535 B CN107931535 B CN 107931535B
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- core
- casting
- core bar
- volute
- sand
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Classifications
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- 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
- B22C9/106—Vented or reinforced cores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
- B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
Abstract
The invention relates to a core bar of a volute casting sand core for a large-scale compressor and a manufacturing method thereof in the technical field of casting, wherein the core bar comprises an outer ring core bar and an inner ring core bar which are concentric, a plurality of radial beams are connected to the inner ring core bar and the outer ring core bar, the outer ring core bar is positioned in the central area of a convoluted passage sand core of a volute, and the inner ring core bar is positioned at the inner side of a narrow slit part of the volute. The core bone structure adopts the radiation beam with the hollow structure, and the cooling gas is used for forced cooling in the casting process, so that the problem that the core bone at the thin neck part is broken due to the reduction of strength caused by overhigh temperature in the casting process is solved.
Description
Technical Field
The invention relates to the technical field of casting, in particular to a core bar for a large compressor volute casting sand core and a manufacturing method thereof.
Background
An air compressor is a device commonly used in the industry for producing compressed air, wherein a volute is the core component of a centrifugal compressor. The inner surface of the volute is of an irregular curved surface structure, the volute is generally produced by a casting mode, the structure of the volute is shown in figures 1 and 2, and the volute 1 is structurally characterized by a spiral channel 1A with gradually changed cross section and a circle of narrow slits 1B arranged on the inner side of the wall of the channel 1A in the direction of a centre of gyration. The sand core structure for casting is shown in fig. 3, a cylindrical annular channel sand core 2A for forming a channel 1A is connected with a central cylindrical core head 2C through a narrow-neck sand core 2B for forming a narrow slit to form a typical cantilever core with a large head and a narrow neck, during pouring, the channel sand core 2A is surrounded by high-density metal liquid and is subjected to great buoyancy, the narrow-neck part of the narrow-neck sand core 2B for forming the narrow slit is easy to break, and the channel sand core 2A with the large head floats on the surface, so that the upper skin thickness is insufficient and even the skin is transparent.
In order to avoid the problems, the conventional solution is to embed a chaplet in the skin thickness position at the upper part of the casting in the casting pouring direction so as to resist the floating action of the sand core, but the chaplet is surrounded by high-temperature liquid metal, the temperature of the chaplet is rapidly increased, the strength of the chaplet material is rapidly reduced, and thus the chaplet cannot resist the buoyancy action and is deformed. Or the core support can resist the buoyancy of the sand core, but the surface of the sand core where the core support is arranged can not resist the buoyancy effect under the high-temperature condition and is damaged, so that a large amount of adoption is not recommended.
Because the strength of the sand core is low, particularly the high-temperature strength, the steel/iron beam type structure embedded in the sand core is used as a core bar during the sand core molding, and the strength and the rigidity of the sand core are improved. In the patent application specification of the invention with the publication number of CN105945231A and the name of 'core drift prevention and bending resistance core bar for volute casting sand core', the strength of the sand core is increased by a method of increasing the size of the core bar and the spoke density of the core bar. The rigidity of the sand core can be improved to a certain extent by the scheme, but the practical effect is limited because the size of the core bone at the thin neck position is limited by the narrow slit structure of the volute, the upper surface and the lower surface of the core bone at the thin neck position are free of molding sand only by increasing the size of the core bone, and the core bone is in direct contact with high-temperature molten metal to cause the temperature rise of the core bone and the reduction of the strength, so that the core bone is bent and deformed. In addition, as the core bar is directly contacted with molten metal, the core bar can also have a strong chilling effect on the metal, and similar to chilling blocks, the graphite morphology of the cast product at the position is abnormal and the hardness problem is caused.
Disclosure of Invention
The invention provides a core skeleton of a volute casing casting sand core, aiming at the problem that a large-head thin-neck structure of a compressor casing casting sand core in the prior art is easy to deform under the action of buoyancy in the casting process, so as to solve the problems of deformation and fracture of a thin-neck part in the casting process.
The core bar of the volute casting sand core comprises an outer ring core bar and an inner ring core bar which are concentric, a plurality of radial radiation beams are connected to the inner ring core bar and the outer ring core bar, the outer ring core bar is located in the central area of a convoluted passage sand core of a volute, the inner ring core bar is located on the inner side of a narrow slit of the volute, the outer end of each radiation beam extends out of the outer ring core bar, the inner end of each radiation beam extends into the inner side of the inner ring core bar, each radiation beam is of a through hollow structure, and two ends of each radiation beam are respectively connected with a cooling pipe for introducing cooling gas.
Aiming at the problem that the strength of the core sand core bone at the thin neck part is reduced at high temperature in the casting process, the core bone is designed into an inner ring core bone and an outer ring core bone which are respectively used for strengthening the strength of the passage part and the central core head part of the sand core, the inner ring core bone and the outer ring core bone are connected through a radiation beam, the radiant beam is designed into a through hollow structure and is connected with an air inlet pipe and an air outlet pipe for cooling, in the casting process, cooling gas is introduced into the hollow channel of the radiant beam for forced cooling so as to ensure that the radiant beam is at a lower temperature, thus, for the radiant beam mainly bearing bending deformation, the rigidity of the beam cannot be greatly lost due to the hollow structure, the forced cooling through the hollow structure can ensure the rigidity of the core bar in the use state to the maximum extent, thereby preventing the radiation beam from bending and deforming under the action of sand core buoyancy during casting to cause the sand core fracture of the thin neck part. By adopting the core structure, the cross section size of the core can be relatively reduced, and the number of the radiation beams in the core structure can be properly reduced, so that the purposes of optimizing the core structure and preventing the sand core from being broken are achieved.
In order to fix the core bar main body conveniently, the outer ring core bar extends to the core head part outside the volute air inlet corresponding to the sand core.
In order to prevent the forced cooling core bone at the thin neck part from chilling the surrounding pouring liquid, the periphery of the part, corresponding to the casting narrow slit, of the radiant beam is brushed with a high-temperature-resistant casting coating, and the corresponding periphery is wrapped with asbestos cloth.
Preferably, the radiation beam is a hollow square tube structure.
In order to facilitate the manufacture of the core bar, the core bar of the sand core is formed by integral casting.
The invention also provides a manufacturing method of the sand core bar of the volute casing casting, which adopts the lost foam pattern to be embedded in a box for molding and then pouring, when the lost foam is manufactured, the hollow part of the radiation beam is embedded with the embedded casting pipes, and the length of two ends of each embedded casting pipe extending out of two ends of the lost foam is 50-60 mm. According to the manufacturing method of the sand core rib, the lost foam is integrally cast and molded aiming at the integral structure of the core rib, so that the manufacturing process of the core rib can be simplified.
In order to ensure the strength of the radiant beam, the cast-in pipe is made of austenitic stainless steel, the yield strength is greater than 400MPa, and the wall thickness is 6-10 mm.
Drawings
FIG. 1 is a schematic view of a centrifugal compressor volute casting.
Fig. 2 is a cross-sectional view taken along a-a of fig. 1.
FIG. 3 is a schematic structural view of a centrifugal compressor volute casting sand core.
Fig. 4 is a schematic structural view of the core bar of the volute casting sand core of the present invention.
FIG. 5 is a schematic view of the assembly of the core rod, the sand core, the pattern and the cooling tube.
FIG. 6 is a schematic view showing the spatial positions of the core, the casting, and the cooling tube.
Wherein, 1, volute casing casting; 1A channel and 1B narrow slit; 2, sand core; 2A channel sand core; 2B thin-neck sand core: 2C cylindrical core print; 3, a core rod; 3A, an outer ring core bar; 3B, inner ring core ribs; a 3C radiation beam; 4, loading a pattern; 5, discharging a pattern; and 6, cooling the tube.
Detailed Description
As shown in fig. 4, the core bar of the volute casing casting sand core disclosed by the invention comprises an outer ring core bar 3A and an inner ring core bar 3B which are concentric, the inner ring core bar 3B and the outer ring core bar 3A are connected with a plurality of radial radiation beams 3C which are radially arranged, the outer ring core bar 3A is positioned in the central area of the convoluted passage sand core 2A of the volute casing casting 1, the inner ring core bar 3B is positioned at the inner side of the volute narrow slit 1B, the outer ends of the radiation beams 3C extend out of the outer ring core bar 3A, the inner ends of the radiation beams extend into the inner side of the inner ring core bar 3B, the radiation beams 3C are of a through hollow structure, and the two ends of the radiation beams 3C are respectively connected with cooling pipes 6 for. In order to facilitate the fixation of the core bar main body, the outer ring core bar 3A extends to the core head part outside the volute air inlet corresponding to the sand core; in order to prevent the forced cooling core bone at the thin neck part from chilling the surrounding pouring liquid, the periphery of the radiation beam 3C corresponding to the casting narrow slit part is brushed with a high-temperature-resistant casting coating, and the corresponding periphery is wrapped with asbestos cloth; in order to ensure the strength of the radiation beam 3C, the radiation beam 3C in this embodiment is a hollow square tube structure; to facilitate the fabrication of the core rod 3, the core rod of the present embodiment is formed by integral casting.
The core frame structure of the sand core of the invention aims at the problem that the strength of the core frame at the thin neck part is reduced at high temperature in the casting process, the core frame is designed into an inner ring core frame 3A and an outer ring core frame 3B which are respectively used for strengthening the strength of a sand core channel part and a central cylindrical core head 2C part, the inner ring core frame 3A and the outer ring core frame 3B are connected through a radiation beam 3C, the radiation beam 3C is designed into a through hollow structure and is connected with a cooling pipe for introducing cooling gas, the hollow channel of the radiation beam 3C is introduced with cooling gas for forced cooling in the casting process to ensure that the radiation beam is at a lower temperature, thus, for the radiation beam 3C mainly bearing bending deformation, the rigidity of the beam cannot cause too large loss due to the hollow structure, and the rigidity of the core frame in the use state can be ensured to the maximum degree due to the forced cooling through the hollow structure, thereby preventing the radiation beam from bending and deforming under the action of sand core buoyancy during casting to cause the sand core fracture of the thin neck part. In order to prevent the forcibly cooled radiation beam from chilling casting liquid at the narrow gap part of the casting, coating paint on the thin neck part of the radiation beam and wrapping asbestos cloth to prevent the radiation beam at the part from heat transfer with surrounding sand cores. By adopting the core structure, the cross section size of the core can be relatively reduced, and the number of the radiation beams in the core structure can be properly reduced, so that the purposes of optimizing the core structure and preventing the sand core from being broken are achieved.
The sand core frame with the structure of the embodiment has various manufacturing methods, and according to the structural characteristics of the core frame, the sand core frame can be manufactured by adopting an integral casting forming method, wherein the sand core frame is particularly convenient to pour after being embedded and molded in a box in a lost foam pattern, when the lost foam is manufactured, the hollow part of the radiation beam is embedded with the embedded casting pipes, and the length of two ends of each embedded casting pipe extending out of two ends of the lost foam is 50-60 mm. In order to ensure the strength of the radiant beam, the cast-in pipe is made of austenitic stainless steel, the yield strength is greater than 400MPa, and the wall thickness is 6-10 mm.
In the method for manufacturing the sand core by embedding the lost foam in the embodiment, the lost foam is integrally cast and molded aiming at the integral structure of the core, so that the manufacturing process of the core can be simplified.
As shown in figure 5, when the sand core is manufactured by the sand core framework of the invention, firstly, a casting coating is coated on the corresponding thin neck part in the middle of the radiant beam 3C, then 3-5 layers of asbestos cloth are coated on the periphery, high temperature resistant coating is brushed outside the asbestos cloth, drying treatment is carried out, then the core framework is placed between an upper model 4 and a lower model 5 of a core box, sand filling operation is carried out, when sand is filled to the horizontal plane of the core framework, cooling pipes 6 for air inlet and outlet are respectively arranged at the two ends of each radiant beam, sand filling is continued, and the edge of each cooling pipe extends to the upper part of the central cylindrical core head 2C, and an inlet and an outlet are exposed. The schematic spatial position diagram of the sand core frame, the casting and the cooling pipe of the invention is shown in FIG. 6. When the sand mold is closed, cooling extends to the side surface of the upper mold to extend out, and a channel for accommodating the cooling pipe to enter and exit the road is correspondingly arranged in the upper sand mold, so that gas is cooled from the outside of the sand mold during pouring. The introduction of compressed cooling air or other cooling fluid is generally started immediately before the pouring, and the forced cooling time is maintained at least until 24 hours after the pouring is completed. Cooling the mould to a proper temperature and then carrying out sand falling treatment. After the sand is fallen, the core bone can be taken out after cutting.
Claims (5)
1. The core bar of the volute casting sand core comprises an outer ring core bar and an inner ring core bar which are concentric, wherein the inner ring core bar and the outer ring core bar are connected with a plurality of radial radiation beams, the outer ring core bar is positioned in the central area of a convoluted passage sand core of a volute, the inner ring core bar is positioned on the inner side of a narrow slit part of the volute, the outer ends of the radiation beams extend out of the outer ring core bar, the inner ends of the radiation beams extend into the inner side of the inner ring core bar, the radiation beams are of a through hollow structure, and two ends of each radiation beam are respectively connected with a cooling pipe for introducing cooling gas; the casting device is characterized in that the periphery of the radiation beam corresponding to the narrow gap part of the casting is brushed with a high-temperature-resistant casting coating, and the corresponding periphery is wrapped with asbestos cloth; the core bone of the sand core is formed by integral casting.
2. The core leg of a volute casting sand core as defined in claim 1, wherein the outer race leg extends to a core head portion outside the volute air inlet corresponding to the sand core.
3. The corebone of a volute casting sand core of claim 1, wherein said radiant beam is a hollow square tube structure.
4. The manufacturing method of the core frame of the sand core of the volute casing casting according to claim 1, characterized in that after the core frame is molded by embedding in a box in a lost foam pattern, the cast pipes are embedded in the hollow part of the radiant beam during the lost foam molding, and the length of the two ends of each cast pipe extending out of the lost foam is 50-60 mm.
5. The method of making a corewire for a volute casting sand core of claim 4, wherein said insert tube is austenitic stainless steel, has a yield strength greater than 400MPa, and a wall thickness of 6-10 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711202627.5A CN107931535B (en) | 2017-11-27 | 2017-11-27 | Core bar of volute casing casting sand core and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711202627.5A CN107931535B (en) | 2017-11-27 | 2017-11-27 | Core bar of volute casing casting sand core and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107931535A CN107931535A (en) | 2018-04-20 |
| CN107931535B true CN107931535B (en) | 2019-12-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201711202627.5A Active CN107931535B (en) | 2017-11-27 | 2017-11-27 | Core bar of volute casing casting sand core and manufacturing method thereof |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114799051B (en) * | 2022-03-07 | 2023-06-09 | 共享铸钢有限公司 | Casting method for preventing drifting of valve casing casting |
| CN116786765B (en) * | 2023-03-14 | 2024-03-19 | 湖州中联机械制造有限公司 | Mud core structure and preparation method thereof |
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|---|---|---|---|---|
| CN1404941A (en) * | 2002-11-04 | 2003-03-26 | 沪东重机股份有限公司 | Method for casting cast-steel piece with deep-long through hole |
| CN201500765U (en) * | 2009-09-28 | 2010-06-09 | 河南欧迪艾铸造有限公司 | Slender cooling core bar for casting |
| CN202732482U (en) * | 2012-08-30 | 2013-02-13 | 桐乡合德机械有限公司 | Integral arbor for cast spiral case parts |
| CN104043783A (en) * | 2014-06-17 | 2014-09-17 | 中核苏阀横店机械有限公司 | Small-caliber high-class valve body casting core |
| CN105945231A (en) * | 2016-06-02 | 2016-09-21 | 共享装备股份有限公司 | Core drifting-prevention and bending-resistance arbor for volute type casting sand core |
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2017
- 2017-11-27 CN CN201711202627.5A patent/CN107931535B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1404941A (en) * | 2002-11-04 | 2003-03-26 | 沪东重机股份有限公司 | Method for casting cast-steel piece with deep-long through hole |
| CN201500765U (en) * | 2009-09-28 | 2010-06-09 | 河南欧迪艾铸造有限公司 | Slender cooling core bar for casting |
| CN202732482U (en) * | 2012-08-30 | 2013-02-13 | 桐乡合德机械有限公司 | Integral arbor for cast spiral case parts |
| CN104043783A (en) * | 2014-06-17 | 2014-09-17 | 中核苏阀横店机械有限公司 | Small-caliber high-class valve body casting core |
| CN105945231A (en) * | 2016-06-02 | 2016-09-21 | 共享装备股份有限公司 | Core drifting-prevention and bending-resistance arbor for volute type casting sand core |
Non-Patent Citations (1)
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| 蜗壳;缑鹏森等;《金属加工热加工》;20171005(第19期);第59-61页 * |
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| CN107931535A (en) | 2018-04-20 |
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Address after: 750000 No. 298 South st street, Yinchuan economic and Technological Development Zone, the Ningxia Hui Autonomous Region, China Applicant after: Shared Intelligent Equipment Co., Ltd. Address before: 750000 No. 298 South st street, Yinchuan economic and Technological Development Zone, the Ningxia Hui Autonomous Region, China Applicant before: Ningxia Kocel Pattern Co., Ltd. |
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Effective date of registration: 20210819 Address after: 750011 building 4, TMT R & D center, east of No. 5 road, science and Technology Park, Jinfeng District, Yinchuan City, Ningxia Hui Autonomous Region Patentee after: KOCEL INTELLIGENT FOUNDRY INDUSTRY INNOVATION CENTER Co.,Ltd. Address before: 750000 the Ningxia Hui Autonomous Region Yinchuan economic and Technological Development Zone ningshuo South Street No. 298 Patentee before: KOCEL INTELLIGENT EQUIPMENT Co.,Ltd. |
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Effective date of registration: 20211110 Address after: 224599 north of Century Avenue, west of Erkan road and east of Xingfu North Road, Binhai County, Yancheng City, Jiangsu Province Patentee after: Jiangsu gongchi Technology Co., Ltd Address before: 750011 building 4, TMT R & D center, east of No. 5 road, science and Technology Park, Jinfeng District, Yinchuan City, Ningxia Hui Autonomous Region Patentee before: Shared intelligent Casting Industry Innovation Center Co., Ltd |