CN111644574A - Preparation method of reinforced thin-wall sand core - Google Patents
Preparation method of reinforced thin-wall sand core Download PDFInfo
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- CN111644574A CN111644574A CN202010620810.2A CN202010620810A CN111644574A CN 111644574 A CN111644574 A CN 111644574A CN 202010620810 A CN202010620810 A CN 202010620810A CN 111644574 A CN111644574 A CN 111644574A
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- sand
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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
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- 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
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Abstract
The invention discloses a preparation method of a reinforced thin-wall sand core. The reinforced aggregate can play a role in reinforcing the aggregate at the weak part of the sand core, so that the problems of deformation, core breaking and the like of the sand core caused in the processes of core making, carrying, baking and pouring of the thin-wall sand core can be effectively avoided, and the casting defect is reduced.
Description
Technical Field
The invention relates to the technical field of casting, in particular to a preparation method of a reinforced thin-wall sand core.
Background
The sand core is a material for manufacturing a core in casting production and consists of casting sand, a molding sand binder and the like. The function is to form the inner cavity, the hole, the appearance and other parts of the casting. The process of making the core sand into the sand core conforming to the shape of the core box is called core making, and the core making is divided into manual core making and machine core making. The precoated sand is prepared by coating a layer of molding sand of a solid resin film on the surface of sand grains before molding and core making, and adding materials such as a latent curing agent (urotropine), a lubricant (calcium stearate) and the like into thermoplastic phenolic resin through a certain precoating process. The core box is a special mould for manufacturing the sand core and is divided into a common core box, a hot core box and a cold core box according to a core manufacturing method.
In the prior art, casting defects are often caused by insufficient strength when complex thin-wall sand cores are manufactured.
The patent with the publication number of CN104722716B provides a method for molding a complex thin-wall sand core, which is characterized in that a conformal core bar is arranged according to the shape of the sand core, a sawtooth-shaped cast iron reinforcing rib is arranged at the weak position of the sand core, and the core is manufactured manually. The sand core forming method improves the connection strength of the sand core and realizes stable production of the complex water cavity sand core. The patent scheme has the following disadvantages: the adopted mode of arranging the metal reinforcing ribs is not suitable for cleaning in the complex water cavity, and the cleaning difficulty is high; the core bar used in the method needs to be extracted in the cleaning process after the pouring is finished, the shape of the core bar cannot be set to be too complex, otherwise, the core bar is difficult to extract; the sand core forming method has relatively complex process and is not suitable for mechanical core making.
The patent with publication number CN110076285A provides a high temperature resistant and deformation resistant sand core material and a preparation method thereof, the sand core material introduces chromite and steel fiber filaments with excellent chilling effect on the basis of common sand core materials, the chilling capability of the sand core is obviously improved, the periphery of the sand core is solidified and molded before other parts, and the surface finish degree and the dimensional position precision of the inner cavity of a casting are improved. Meanwhile, on the basis of a common sand core material, whiskers with high temperature resistance, high strength and toughness and low cost are introduced, the high temperature deformation resistance of the sand core is improved through the high temperature resistance strengthening and deformation resistance of the whiskers, and the high temperature deformation resistance of the sand core is obviously improved through the high temperature resistance strengthening and deformation resistance of steel fiber wires. The patent scheme has the following disadvantages: the mode of adding steel fiber wires and whiskers into the sand can cause the flowability of the sand to be greatly reduced, and the sand core with a complex structure and small local size cannot be molded at all; and after the casting is cooled, the cleaning work of the sand is very difficult, and the method is only suitable for the sand core with large size and simple structure.
Therefore, how to reduce the casting defects caused by manufacturing complex thin-wall sand cores is a technical problem to be solved by those skilled in the art at present.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for preparing a reinforced thin-wall sand core, which can reinforce a local weak part of the sand core and avoid casting defects caused by insufficient strength of the sand core.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for preparing a reinforced thin-wall sand core is characterized in that in the core making process, the thin wall of the sand core needing to be reinforced is formed in a mode of mixing precoated sand and reinforcing aggregate.
Preferably, in the core making process, the thin wall of the sand core to be strengthened is shot by using prefabricated coated sand, wherein the prefabricated coated sand comprises: basic aggregate, reinforcing aggregate, binder, curing agent and lubricant.
Preferably, in the core making process, the prefabricated precoated sand is adopted to perform sand shooting on the thin wall part of the sand core needing to be strengthened, and the reinforcing aggregate is sprayed at the same time.
Optionally, in the core making process, the prefabricated precoated sand is adopted for the whole sand core to perform sand shooting.
Preferably, the precoated sand includes: 100 parts by weight of base aggregate, 3-7 parts by weight of reinforcing aggregate, 2-4 parts by weight of binder, 0.35-0.5 part by weight of curing agent and 0.2-0.4 part by weight of lubricant.
Preferably, the precoated sand includes: 100 parts by weight of base aggregate, 5 parts by weight of reinforcing aggregate, 3 parts by weight of binder, 0.45 part by weight of curing agent and 0.3 part by weight of lubricant.
Preferably, the basic aggregate is silica sand, the binder is phenolic resin or furan resin, the curing agent is urotropine aqueous solution, and the lubricant is calcium stearate.
Preferably, in the core making process, the reinforcing aggregate is firstly placed at the thin wall of the sand core to be reinforced, and then the coated sand is injected at the thin wall of the sand core to be reinforced.
Optionally, the reinforcing aggregate is carbon fiber, or asbestos fiber, or ceramic fiber, or glass fiber.
According to the preparation method of the reinforced thin-wall sand core, in the core making process, the thin wall part of the sand core needing to be reinforced is formed in a mode of mixing the precoated sand and the reinforcing aggregate. The reinforced aggregate can play a role in reinforcing the aggregate at the weak part of the sand core, so that the problems of deformation, core breaking and the like of the sand core caused in the processes of core making, carrying, baking and pouring of the thin-wall sand core can be effectively avoided, and the casting defect is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a method of making a strengthened thin-wall sand core according to a second embodiment of the present invention;
fig. 2 is a schematic diagram of sand shooting at a thin wall of a sand core in the first embodiment of the present invention.
In fig. 2:
1-sand shooting nozzle, 2-core box inner cavity, 3-sand core thin wall, 4-jet nozzle, and 5-prefabricated precoated sand.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 and 2, fig. 1 is a flow chart of a method for preparing a reinforced thin-wall sand core according to an embodiment of the present invention; fig. 2 is a schematic diagram of sand shooting at a thin wall of a sand core in the embodiment of the present invention.
The invention provides a preparation method of a reinforced thin-wall sand core for manufacturing a core by mixing reinforced aggregate into precoated sand, aiming at the problem that the casting defect is easily caused by insufficient strength of a complex thin-wall sand core. The reinforced aggregate can play a role in reinforcing the aggregate at the weak part of the sand core, so that the problems of deformation, core breaking and the like of the sand core caused in the processes of core making, carrying, baking and pouring of the thin-wall sand core can be effectively avoided, and the casting defect is reduced.
The preparation method provided by the scheme can be implemented in various ways according to different modes of mixing the reinforcing aggregate into the precoated sand. Please refer to the following embodiments.
Example one
In the first embodiment, in the core making process, the sand shooting is performed on the thin wall of the sand core needing to be strengthened by using prefabricated precoated sand, wherein the prefabricated precoated sand comprises: basic aggregate, reinforcing aggregate, binder, curing agent and lubricant. In the embodiment, the reinforcing aggregate and the common precoated sand are mixed to prepare the special prefabricated precoated sand, so that the reinforcing aggregate can play a role in reinforcing the aggregate at the weak position when the prefabricated precoated sand is used for carrying out sand shooting on the thin wall position of the sand core.
Referring to fig. 2, in the present embodiment, two sand shooting nozzles 1 are used to shoot precoated sand into an inner cavity 2 of a core box, and in addition, a single injection system is also provided to shoot prefabricated precoated sand 5 into a thin wall part 3 of a sand core through an injection nozzle 4.
In the first embodiment, two sets of sand shooting systems are designed on core making equipment, a spray nozzle 4 is independently arranged at a sand core thin wall part 3, mixed prefabricated precoated sand is injected into the sand core thin wall part 3, and common precoated sand is still used for shooting and making cores at other parts of the sand core.
Example two
In the second embodiment, in the core making process, the prefabricated precoated sand is adopted to perform sand shooting on the thin wall part of the sand core needing to be strengthened, and the reinforcing aggregate is sprayed at the same time. The embodiment is further improved on the basis of the first embodiment, and not only is the prefabricated precoated sand containing the reinforcing aggregate used for shooting the sand at the thin wall part of the sand core, but also the reinforcing aggregate is sprayed at the thin wall part, so that the reinforcing effect of the reinforcing aggregate serving as a reinforcing rib is further enhanced.
Referring to fig. 1, the specific processing flow of the second embodiment is as follows:
s1: the core making machine gives a sand requiring signal, and the sand supply system supplies the prefabricated precoated sand to the upper part of the core making machine and respectively stores the prefabricated precoated sand;
s2: and respectively injecting the prefabricated precoated sand into the inner cavity of the core box, wherein the sand injection pressure is generally 0.3-0.5 Mpa, the sand injection time is 5-9 s, and the exhaust time is 5-9 s. Independently arranging a jet system for jetting the reinforcing aggregate, arranging a jet nozzle at the thin wall of the sand core, starting the reinforcing aggregate jet system at a proper time in the core making process of the sand core, and simultaneously jetting the prefabricated precoated sand, thereby finishing the reinforcement of the thin wall of the sand core;
s3: after sand shooting is finished, curing the sand core by heating the core box, wherein the heating temperature is generally set to be 200-230 ℃, and the curing time is 70-100 s; if the core box is the cold core box, the sand core is solidified by adopting a corresponding cold core solidification mode;
s4: and after the sand core is cured, opening the core box and taking out the qualified sand core.
EXAMPLE III
In the third embodiment, in the core making process, the prefabricated coated sand is adopted for the whole sand core to perform sand shooting, and the second embodiment is further improved, so that the prefabricated coated sand containing the reinforcing aggregate is used for shooting the sand at the thin wall part of the sand core, and other parts of the sand core are also shot, and the whole sand core is reinforced. The embodiment is suitable for the core making process of the integral complex thin-wall sand core, and the core making equipment only needs to be provided with one set of sand shooting system.
Example four
In the fourth embodiment, in the core making process, the reinforcing aggregate is placed at the thin wall of the sand core to be reinforced, and then the coated sand is injected at the thin wall of the sand core to be reinforced. The effect realized in this embodiment is similar to the effect of injecting the pre-coated sand in the above embodiment, and the thin wall of the sand core can be strengthened.
The precoated sand includes: 100 parts by weight of base aggregate, 3-7 parts by weight of reinforcing aggregate, 2-4 parts by weight of binder, 0.35-0.5 part by weight of curing agent and 0.2-0.4 part by weight of lubricant.
Preferably, the precoated sand includes: 100 parts by weight of base aggregate, 5 parts by weight of reinforcing aggregate (such as carbon fiber), 3 parts by weight of binder, 0.45 part by weight of curing agent, and 0.3 part by weight of lubricant.
Preferably, the basic aggregate is ordinary silica sand, the angular coefficient is less than 1.3, the content of silicon dioxide is more than 97.5%, the reinforcing aggregate is preferably carbon fiber, the binder is phenolic resin or furan resin, the curing agent is urotropine aqueous solution, the mass ratio of the urotropine aqueous solution is 1:1, and the lubricant is calcium stearate.
The reinforcing aggregate in the scheme is carbon fiber, and asbestos fiber, ceramic fiber, glass fiber and the like can be selected and used, and the materials can improve the strength of the sand core.
The invention has the following beneficial effects:
1) according to the scheme, the reinforcing aggregates such as carbon fibers and the like play a role of reinforcing ribs after the sand core is prepared, so that the problems of deformation, core breakage and the like of the thin-wall sand core can be effectively avoided, and the casting defect is reduced;
2) the scheme can only strengthen local weak parts of the sand core, and reduces the cost compared with the integral strengthening of the sand core;
3) the scheme has simple operation, simple core making process, suitability for mechanical production and high core making efficiency;
4) the difficulty of foundry goods clearance can not be increased to this scheme.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. The preparation method of the reinforced thin-wall sand core is characterized in that in the core making process, the thin wall part of the sand core needing to be reinforced is formed by adopting a mode of mixing precoated sand and reinforcing aggregate.
2. The method for preparing the reinforced thin-wall sand core according to claim 1, wherein in the core making process, the thin wall of the sand core to be reinforced is shot by using prefabricated coated sand, wherein the prefabricated coated sand comprises: basic aggregate, reinforcing aggregate, binder, curing agent and lubricant.
3. The method for preparing the reinforced thin-wall sand core according to claim 2, wherein in the core making process, the prefabricated precoated sand is adopted to perform sand shooting on the thin wall of the sand core to be reinforced, and the reinforcing aggregate is sprayed at the same time.
4. The method for preparing the reinforced thin-wall sand core according to claim 2, wherein the prefabricated coated sand is adopted for sand shooting on the whole sand core in the core making process.
5. The method for preparing the reinforced thin-walled sand core of claim 2, wherein the pre-coated sand comprises: 100 parts by weight of base aggregate, 3-7 parts by weight of reinforcing aggregate, 2-4 parts by weight of binder, 0.35-0.5 part by weight of curing agent and 0.2-0.4 part by weight of lubricant.
6. The method for preparing the reinforced thin-walled sand core of claim 5, wherein the pre-coated sand comprises: 100 parts by weight of base aggregate, 5 parts by weight of reinforcing aggregate, 3 parts by weight of binder, 0.45 part by weight of curing agent and 0.3 part by weight of lubricant.
7. The method of claim 5, wherein the base aggregate is silica sand, the binder is phenolic resin or furan resin, the curing agent is an aqueous solution of urotropine, and the lubricant is calcium stearate.
8. The method for preparing the reinforced thin-wall sand core according to claim 1, wherein in the core making process, the reinforced aggregate is firstly placed at the thin wall of the sand core to be reinforced, and then the coated sand is injected at the thin wall of the sand core to be reinforced.
9. The method of any one of claims 1 to 8, wherein the reinforcing aggregate is carbon fiber, or asbestos fiber, or ceramic fiber, or glass fiber.
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| CN202010620810.2A CN111644574A (en) | 2020-06-30 | 2020-06-30 | Preparation method of reinforced thin-wall sand core |
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| CN202010620810.2A CN111644574A (en) | 2020-06-30 | 2020-06-30 | Preparation method of reinforced thin-wall sand core |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113020543A (en) * | 2021-03-01 | 2021-06-25 | 潍柴动力股份有限公司 | Sand core forming method and ink-jet printing device |
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