阅读说明：本技术 一种具有曲面流道的叶轮陶瓷型芯的制备方法 (Preparation method of ceramic core of impeller with curved-surface flow channel ) 是由 彭兴彦 彭刚 万冬梅 陈国伟 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种具有曲面流道的叶轮陶瓷型芯的制备方法,包括以下步骤：A、镶入式陶瓷活动块的制备；B、叶轮陶瓷型芯蜡胚的制备：将所述步骤A制得的镶入式陶瓷活动块装配于陶瓷型芯模具的内腔,经射蜡成型后制得叶轮陶瓷型芯蜡胚；C、对所述步骤B制得的叶轮陶瓷型芯蜡胚进行烧结,烧结后清除所述镶入式陶瓷活动块。采用预制的陶瓷型活动块替代金属型活动块,陶瓷型活动块与陶芯模具组合经射蜡脱模后留在陶瓷型芯蜡胚内部,制得的具有曲面流道的叶轮陶瓷型芯的尺寸精度高、变形量小,解决了现有使用金属活动块组合模具制备具有曲面流道的叶轮陶瓷型芯容易产生合模线,增加了蜡胚的修理难度的问题。(The invention discloses a preparation method of an impeller ceramic core with a curved-surface flow channel, which comprises the following steps: A. preparing an embedded ceramic movable block; B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block prepared in the step A in an inner cavity of a ceramic core mold, and performing wax injection molding to prepare an impeller ceramic core wax blank; C. and B, sintering the ceramic core wax blank of the impeller prepared in the step B, and removing the embedded ceramic movable block after sintering. The prefabricated ceramic movable block is adopted to replace a metal movable block, the ceramic movable block and the ceramic core die are combined and left in a ceramic core wax blank after wax injection and demoulding, the size precision of the prepared impeller ceramic core with the curved-surface runner is high, the deformation is small, and the problems that a mold closing line is easily generated and the repair difficulty of the wax blank is increased when the impeller ceramic core with the curved-surface runner is prepared by using the metal movable block combined die are solved.)

1. The preparation method of the ceramic core of the impeller with the curved surface flow channel is characterized in that a prefabricated embedded ceramic movable block is adopted to replace a local or whole metal movable block and is applied to the preparation of the ceramic core of the impeller with the curved surface flow channel, the ceramic core of the impeller is provided with a plurality of impeller blade flow channels, the impeller blade flow channels are arranged in a bending and partial twisting mode, and the preparation method comprises the following steps:

A. preparing an embedded ceramic movable block: uniformly stirring and mixing a ceramic material, a pore-forming agent and a binder to obtain a mixture, carrying out extrusion forming and drying solidification on the mixture to obtain an embedded ceramic movable block, wherein the embedded ceramic movable block is provided with a twisted surface;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to prepare an impeller ceramic core wax blank, wherein the embedded ceramic movable block is embedded and wrapped in the impeller ceramic core wax blank;

C. and C, sintering the ceramic core wax blank of the impeller prepared in the step B, removing the embedded ceramic movable blocks after sintering, forming impeller blade runners with the same shapes as the embedded ceramic movable blocks on the sintered body after removing each embedded ceramic movable block, and obtaining the ceramic core of the impeller with the curved runners after removing.

2. The method for preparing the ceramic core of the impeller with the curved-surface flow channel as claimed in claim 1, wherein when a prefabricated embedded ceramic movable block is used to replace a local metal movable block, in the step B, the embedded ceramic movable block is embedded and wrapped in a twisted area in the flow channel of the wax blank of the ceramic core of the impeller.

3. The method for preparing the ceramic core of the impeller with the curved-surface flow channel as claimed in claim 1, wherein in the step A, the raw materials of the embedded ceramic movable block comprise 75-85 parts by weight of ceramic material, 5-10 parts by weight of pore-forming agent and 8-12 parts by weight of binder.

4. The method for preparing the ceramic core of the impeller with the curved-surface runner according to claim 1, wherein the ceramic material of the embedded ceramic movable block is one or a combination of two of fused corundum and silicon carbide;

the grain composition of the ceramic material is as follows according to the weight percentage: 20-30% of raw materials with the granularity of 80 meshes and 70-80% of raw materials with the granularity of 40 meshes.

5. The method for preparing the ceramic core for the impeller with the curved flow channel as claimed in claim 1, wherein the pore-forming agent embedded in the ceramic movable block is at least one of graphite fine powder, flour and millet powder, and the particle size of the pore-forming agent is 1000 meshes.

6. The method for preparing the ceramic core of the impeller with the curved-surface flow channel as claimed in claim 1, wherein in the step A, the extrusion forming pressure is 5-10 MPa, and the forming temperature is 100-150 ℃;

the drying temperature for drying and curing is 140-160 ℃.

7. The method for preparing the ceramic core of the impeller with the curved-surface flow channel according to claim 1, wherein in the step C, in the process of sintering the wax blank of the ceramic core of the impeller prepared in the step B, the glue removing stage is to heat the ceramic core from 100 ℃ to 450 ℃ at a heating rate of 1-2 ℃/min, and the sintering stage is to keep the temperature at 1150-1200 ℃ for 4-8 hours.

8. The method for preparing the ceramic core of the impeller with the curved-surface flow channel according to claim 1, wherein in the step B, the wax injection temperature of the wax injection molding is 65-75 ℃, and the wax injection pressure is 0.4-0.8 MPa.

9. The method for preparing the ceramic core of the impeller with the curved-surface flow channel as claimed in claim 1, wherein the strength of the embedded ceramic movable block is not less than 1 MPa.

10. The method for preparing the ceramic core for the impeller with the curved flow channel as claimed in claim 1, wherein in the step C, the embedded ceramic movable block in the impeller blade flow channel is partially cleaned by using a tool, and then the cleaning of the rest part of the embedded ceramic movable block in the impeller blade flow channel is completed by using compressed air.

Technical Field

The invention relates to the technical field of ceramic cores, in particular to a preparation method of an impeller ceramic core with a curved-surface flow channel.

Background

In the manufacturing process of the impeller casting, because the curved surface of the inner runner of the impeller casting has various changes according to different design requirements, the ceramic core can be adopted for producing the impeller casting by precision casting, but because the inner runner structure of the ceramic core of the impeller is complex, the mold design difficulty of the ceramic core of the impeller is high, a plurality of types of products can not be formed by fixed molds, in the runner areas with complex curvature, the ceramic core of the impeller can be formed by usually needing some auxiliary movable modules, at present, some problems can occur when the ceramic core of the impeller is manufactured by matching the metal movable blocks with the ceramic core mold of the impeller, such as the occurrence of a mold closing line caused by the combination of the metal movable blocks and the increase of the repair difficulty of a wax blank, and simultaneously, the metal movable blocks are required to be pulled out independently after forming, and the movable blocks are difficult to pull out at the positions with too high curvature, can cause the deformation of the wax embryo and affect the product quality.

Disclosure of Invention

Aiming at the problems brought forward by the background technology, the invention aims to provide a preparation method of an impeller ceramic core with a curved-surface runner, wherein a prefabricated ceramic movable block is adopted to replace a metal movable block, the ceramic movable block is left in a ceramic core wax blank after being demoulded, the prepared impeller ceramic core with the curved-surface runner is high in size precision and small in deformation, the problems that a mold closing line is easy to generate and the wax blank repair difficulty is increased when the existing impeller ceramic core with the curved-surface runner is prepared by using a metal movable block combined mold are solved, and the problems that the wax blank is deformed and the product quality is influenced because the metal movable block needs to be pulled out independently are solved.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of an impeller ceramic core with a curved surface flow channel adopts a prefabricated embedded ceramic movable block to replace a local or whole metal movable block, and is applied to the preparation of the impeller ceramic core with the curved surface flow channel, the impeller ceramic core is provided with a plurality of impeller blade flow channels, the impeller blade flow channels are arranged in a bending and partial twisting mode, and the preparation method comprises the following steps:

A. preparing an embedded ceramic movable block: uniformly stirring and mixing a ceramic material, a pore-forming agent and a binder to obtain a mixture, carrying out extrusion forming and drying solidification on the mixture to obtain an embedded ceramic movable block, wherein the embedded ceramic movable block is provided with a twisted surface;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to prepare an impeller ceramic core wax blank, wherein the embedded ceramic movable block is embedded and wrapped in the impeller ceramic core wax blank;

C. and C, sintering the ceramic core wax blank of the impeller prepared in the step B, removing the embedded ceramic movable blocks after sintering, forming impeller blade runners with the same shapes as the embedded ceramic movable blocks on the sintered body after removing each embedded ceramic movable block, and obtaining the ceramic core of the impeller with the curved runners after removing.

Further, when the prefabricated embedded ceramic movable block is used for replacing a local metal movable block, in the step B, the embedded ceramic movable block is embedded and wrapped in a twisted area in a flow channel of the ceramic core wax blank of the impeller.

Further, in the step A, the raw materials of the embedded ceramic movable block comprise 75-85 parts by weight of a ceramic material, 5-10 parts by weight of a pore-forming agent and 8-12 parts by weight of a binder.

Furthermore, the ceramic material of the embedded ceramic movable block is one or a combination of two of fused corundum and silicon carbide;

the grain composition of the ceramic material is as follows according to the weight percentage: 20-30% of raw materials with the granularity of 80 meshes and 70-80% of raw materials with the granularity of 40 meshes.

Further, the pore-forming agent of the inserted ceramic movable block is at least one of graphite fine powder, flour and millet powder, and the particle size of the pore-forming agent is 1000 meshes.

In the step A, the forming pressure of the extrusion forming is 5-10 MPa, and the forming temperature is 100-150 ℃;

the drying temperature for drying and curing is 140-160 ℃.

Further, in the step C, in the process of sintering the ceramic core wax blank of the impeller prepared in the step B, the binder removal stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at a heating rate of 1-2 ℃/min, and the sintering stage is to keep the temperature at 1150-1200 ℃ for 4-8 hours.

In the step B, the temperature of the wax injection for the wax injection molding is 65-75 ℃, and the pressure of the wax injection is 0.4-0.8 MPa.

Further, the strength of the ceramic insert movable block is not less than 1 MPa.

In step C, a tool is used to partially clean the embedded ceramic movable block in the impeller blade flow passage, and then compressed air is used to complete the cleaning of the remaining embedded ceramic movable block in the impeller blade flow passage.

Compared with the prior art, the embodiment of the invention has the following beneficial effects:

1. the embedded ceramic movable blocks are prepared by ceramic materials, pore-forming agents and binders through extrusion forming, drying and curing, have certain strength and high refractoriness, are not sintered during the sintering process, do not react with an impeller ceramic core body during the sintering process, and are not deformed during wax injection molding, and simultaneously, because the pore-forming agents and the binders are added, cavities are formed after glue removal and sintering, so that the embedded ceramic movable blocks embedded in a wax blank of the impeller ceramic core are easy to clean, the embedded ceramic movable blocks are cleaned after sintering, impeller blade runners with the same shapes as the embedded ceramic movable blocks are formed on a sintered body after cleaning of each embedded ceramic movable block, and finally, the impeller ceramic core with a curved runner is prepared, and the embedded ceramic movable blocks are used for replacing metal movable blocks, after wax injection molding, the ceramic core wax blank of the impeller is taken out of the mold, the embedded ceramic movable block does not need to be pulled out of the ceramic core wax blank of the impeller, and the embedded ceramic movable block and the ceramic core wax blank of the impeller are integrally sintered at high temperature, so that the prepared ceramic core of the impeller with the curved-surface runner has high dimensional precision and small deformation, the problems that a mold closing line is easy to generate and the wax blank repair difficulty is increased when the ceramic core of the impeller with the curved-surface runner is prepared by using a metal movable block combined mold in the prior art are solved, and the problems that the wax blank is deformed and the product quality is influenced because the metal movable block needs to be pulled out independently are solved;

2. b, sintering the ceramic core wax blank of the impeller ceramic core prepared in the step B, specifically, loading the ceramic core wax blank of the impeller into a sagger by adopting alumina embedded powder and then sintering, heating the temperature from 100 ℃ to 450 ℃ at a heating rate of 1-2 ℃/min in a glue discharging stage, and in the low-temperature glue discharging process, controlling the heating rate to prevent the ceramic core from cracking caused by rapid thermal decomposition of the embedded ceramic movable block, and naturally cooling after the sintering stage of keeping the temperature at 1150-1200 ℃ for 4-8 h, so that the prepared ceramic core of the impeller with the curved-surface flow channel has high dimensional accuracy and small deformation;

3. the raw materials of the embedded ceramic movable block are uniformly mixed through stirring, and are prepared after extrusion forming and drying solidification, the strength of the embedded ceramic movable block is not less than 1MPa, so that the embedded ceramic movable block cannot deform in the step B wax injection molding process, and therefore the size precision of the impeller ceramic core is guaranteed to be prepared, and the impeller ceramic core is prevented from deforming.

Drawings

FIG. 1 is a schematic perspective view of a ceramic core for an impeller having curved flow channels in accordance with one embodiment of the present invention;

FIG. 2 is a schematic front view of the ceramic core of the impeller shown in FIG. 1 with curved flow channels;

FIG. 3 is a schematic perspective view of a ceramic core for an impeller having curved flow channels in accordance with one embodiment of the present invention;

FIG. 4 is a schematic front view of the ceramic core of the impeller shown in FIG. 3 with curved flow channels;

wherein: the device comprises an impeller ceramic core 1, an impeller blade runner 2 and an embedded ceramic movable block 3.

Detailed Description

A preparation method of an impeller ceramic core with curved surface flow channels adopts a prefabricated embedded ceramic movable block 3 to replace a local or whole metal movable block, and is applied to an impeller ceramic core 1 with curved surface flow channels, as shown in figures 1 to 4, the impeller ceramic core 1 is provided with a plurality of impeller blade flow channels 2, the impeller blade flow channels 2 are arranged in a bending and partial twisting mode, and the preparation method comprises the following steps:

A. preparation of the embedded ceramic movable block 3: uniformly stirring and mixing a ceramic material, a pore-forming agent and a binder to obtain a mixture, carrying out extrusion forming and drying solidification on the mixture to obtain an embedded ceramic movable block 3, wherein the embedded ceramic movable block 3 is provided with a twisted surface;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block 3 prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to prepare an impeller ceramic core wax blank, wherein the embedded ceramic movable block 3 is embedded in the impeller ceramic core wax blank;

C. and B, sintering the ceramic core wax blank of the impeller prepared in the step B, removing the embedded ceramic movable blocks 3 after sintering, forming impeller blade flow channels 2 with the same shape as the embedded ceramic movable blocks 3 on the sintered body after removing each embedded ceramic movable block 3, and obtaining the ceramic core 1 of the impeller with the curved flow channels after removing.

The embedded ceramic movable block 3 is prepared by adopting a ceramic material, a pore-forming agent and a binder through extrusion forming, drying and curing, has certain strength and high refractoriness, does not react with a wax blank body of an impeller ceramic core, and does not deform during wax injection molding, and simultaneously, because the pore-forming agent and the binder are added, a cavity is formed after glue removal and sintering, so that the embedded ceramic movable block 3 embedded in the wax blank of the impeller ceramic core is easy to clean, the embedded ceramic movable block 3 is cleaned after sintering, an impeller blade runner 2 with the same shape as the embedded ceramic movable block 3 is formed on a sintered body after cleaning each embedded ceramic movable block 3, and finally, the impeller ceramic core 1 with a curved surface runner structure is prepared, and the embedded ceramic movable block 3 is adopted to replace a metal movable block, after wax injection molding, the ceramic core wax blank of the impeller is taken out of the mold, the embedded ceramic movable block 3 does not need to be pulled out of the ceramic core wax blank of the impeller, the embedded ceramic movable block 3 and the ceramic core wax blank of the impeller are subjected to integral high-temperature sintering, the prepared ceramic core 1 of the impeller with the curved-surface runner structure is high in size precision and small in deformation, the problems that a mold closing line is easily generated and the wax blank repair difficulty is increased when the ceramic core of the impeller with the curved-surface runner structure is prepared by using a metal movable block combined mold in the prior art are solved, and the problems that the wax blank is deformed and the product quality is influenced due to the fact that the metal movable block needs to be pulled out independently are solved.

Further, when the prefabricated embedded ceramic movable block is used for replacing a local metal movable block, in the step B, after the ceramic core wax blank of the impeller is manufactured through wax injection molding, the method further comprises the step of removing the metal movable block in the ceramic core wax blank of the impeller, wherein the embedded ceramic movable block is embedded and wrapped in a twisted area in a runner of the ceramic core wax blank of the impeller, the metal movable block is difficult to pull out in the twisted area in the runner due to the complex runner, and the metal movable block needs to be split (namely, split into two movable blocks) in the area, so that the prefabricated embedded ceramic movable block 3 is used for replacing the local metal movable block, the metal movable block is still used in other positions, the metal movable block can be reused, and the preparation cost can be effectively reduced.

Further, in the step a, the raw materials of the embedded ceramic movable block 3 include, by weight, 75-85 parts of a ceramic material, 5-10 parts of a pore-forming agent, and 8-12 parts of a binder.

In the step a, the raw materials of the embedded ceramic movable block 3 include ceramic materials, the amount of the ceramic materials depends on the size and the shape of the embedded ceramic movable block 3, the size of the embedded ceramic movable block 3 is larger, then the amount of the ceramic materials in the embedded ceramic movable block 3 is increased, the amount of the binder is reduced, the binder is ensured, when the strength of the embedded ceramic movable block 3 is sufficient, glue can be easily discharged, the smaller the size of the embedded ceramic movable block 3 is, the smaller the amount of the ceramic materials needs to be reduced, the amount of the binder is increased, the strength of the embedded ceramic movable block 3 is ensured, and the collapsibility of the embedded ceramic movable block after the completion of sintering is improved.

Furthermore, the ceramic material of the embedded ceramic movable block 3 is one or a combination of two of fused corundum and silicon carbide;

the grain composition of the ceramic material is as follows according to the weight percentage: 20-30% of raw materials with the granularity of 80 meshes and 70-80% of raw materials with the granularity of 40 meshes.

In the raw materials of embedded ceramic movable block 3, ceramic material choose for use with the material that impeller ceramic core wax embryo can not take place the reaction under sintering temperature, like electric smelting corundum and carborundum, guarantee embedded ceramic movable block 3 with impeller ceramic core wax embryo can not take place the reaction, can not warp when penetrating the wax shaping, among the ceramic material, thicker granule is more, makes embedded ceramic movable block 3 conveniently clears up after the sintering is accomplished, through adding the less fine granule of part, is for improving the smooth finish on embedded ceramic movable block 3 surface, if thicker granule is too much, and less than fine granule leads to easily embedded ceramic movable block 3's intensity is poor, and the smooth finish on runner surface is poor after the clearance.

Preferably, the pore-forming agent of the inserted ceramic movable block 3 is at least one of graphite fine powder, flour and millet powder, and the particle size of the pore-forming agent is 1000 meshes.

The porosity of the embedded ceramic movable block 3 after sintering is increased by adding the pore-forming agent, so that the collapsibility of the embedded ceramic movable block 3 is increased, collapsibility cleaning is facilitated, meanwhile, the hardness of the embedded ceramic movable block 3 can be increased, the graphite fine powder has a pore-forming effect and is equivalent to a lubricant, and the performance of the embedded ceramic movable block 3 after extrusion forming is effectively improved;

the granularity of pore-forming agent is 1000 meshes, and pore-forming agent granule can disperse inside the ceramic body of embedded ceramic movable block, increases the collapsibility performance after the sintering, can provide lubricated effect at the in-process of extrusion simultaneously, improves the performance of extrusion.

Preferably, the binder of the ceramic movable insert 3 is at least one of water-soluble polypropylene emulsion, water-soluble phenolic resin, hypromellose emulsion and gum arabic.

Through with ceramic material with the binder mixes, the binder can be right ceramic material plays the effect of bonding, guarantees the intensity of embedded ceramic movable block 3 makes after extrusion forming and drying solidification embedded ceramic movable block 3 can not warp when penetrating the wax shaping.

Preferably, in the step A, the extrusion forming pressure is 5-10 MPa, and the forming temperature is 100-150 ℃;

the drying temperature for drying and curing is 140-160 ℃.

Preferably, the drying temperature of the drying and curing is 150 ℃.

The ceramic raw material and the binder are mixed, then extrusion molding is carried out, 5-10 MPa of molding pressure is applied, the raw material is hardened at 100-150 ℃, the embedded ceramic movable block 3 is obtained, wherein the pressure is adjusted according to the size and the structure of the embedded ceramic movable block 3, if the molding pressure of the extrusion molding is too low and the molding temperature is too low, the embedded ceramic movable block 3 is possibly poor in molding quality, and is easy to deform during wax injection molding.

Further, in the step C, in the process of sintering the ceramic core wax blank of the impeller prepared in the step B, the binder removal stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at a heating rate of 1-2 ℃/min, and the sintering stage is to keep the temperature at 1150-1200 ℃ for 4-8 hours.

Preferably, in the step C, in the process of sintering the ceramic core wax blank of the impeller prepared in the step B, the binder removal stage is to heat the ceramic core wax blank of the impeller from 100 ℃ to 450 ℃ at a heating rate of 1 ℃/min.

And B, sintering the ceramic core wax blank of the impeller ceramic core prepared in the step B, specifically, loading the ceramic core wax blank of the impeller into a sagger by adopting alumina embedded powder, then sintering, heating from 100 ℃ to 450 ℃ at a heating rate of 1-2 ℃/min in a glue discharging stage, and in the low-temperature glue discharging process, controlling the heating rate to prevent the ceramic core from cracking caused by rapid thermal decomposition of the embedded ceramic movable block 3, and naturally cooling after the sintering stage of keeping the temperature at 1150-1200 ℃ for 4-8 h.

Specifically, an adjustable intermittent sintering furnace is adopted for sintering, so that different sintering curves can be controlled, and the sintering effect is ensured.

Preferably, in the step B, the wax injection temperature of the wax injection molding is 65-75 ℃, and the wax injection pressure is 0.4-0.8 MPa.

And C, assembling the embedded ceramic movable block 3 prepared in the step A in a ceramic core mold, then carrying out wax injection molding, preparing the ceramic core wax blank of the impeller after the wax injection molding, controlling the wax injection temperature to be 65-75 ℃ and the wax injection pressure to be 0.4-0.8 MPa, taking the ceramic core wax blank of the impeller out of the mold after the molding, embedding the embedded ceramic movable block 3 in an impeller blade runner 2 of the ceramic core wax blank of the impeller, and then sintering, wherein the wax injection pressure is set within the range, so that the embedded ceramic movable block 3 is prevented from being shot off due to overlarge wax injection pressure.

Further, the strength of the ceramic insert movable block 3 is not less than 1 MPa.

The raw materials of the embedded ceramic movable block 3 are uniformly mixed through stirring, and are prepared after extrusion forming and drying solidification, the embedded ceramic movable block 3 has the strength not less than 1MPa, so that the embedded ceramic movable block 3 cannot deform in the wax injection molding process in the step B, and therefore the size precision of the impeller ceramic core 1 is ensured to be prepared, and the deformation of the impeller ceramic core 1 is avoided.

Specifically, in the step C, a tool is used to partially clean the embedded ceramic movable block 3 in the impeller blade flow passage 2, and then compressed air is used to complete the cleaning of the remaining part of the embedded ceramic movable block 3 in the impeller blade flow passage 2.

After the ceramic core wax blank of the impeller prepared in the step B is sintered, firstly, tools such as a drill bit or other sharp objects are used for partially cleaning the embedded ceramic movable block in the impeller blade runner 2, then, compressed air is used for cleaning the rest part of the embedded ceramic movable block in the impeller blade runner, the cleaning is simple and convenient, the cleaning effect is good, the prepared embedded ceramic movable block 3 is high in quality, and specifically, after the embedded ceramic movable block 3 is cleaned, the surface of the ceramic core 1 of the impeller can be polished by fine sand paper so as to improve the surface flatness and the size precision of the ceramic core 1 of the impeller.

The technical solution of the present invention is further explained by the following embodiments.

In order to facilitate an understanding of the present invention, a more complete description of the present invention is provided below. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

A method for preparing an impeller ceramic core with a curved surface runner structure adopts a prefabricated embedded ceramic movable block 3 to replace a local metal movable block to prepare an impeller ceramic core 1 shown in figures 1 and 2, and comprises the following steps:

A. preparation of the embedded ceramic movable block 3: according to the weight parts, 80 parts of ceramic material (specifically the combination of electro-fused corundum and silicon carbide, wherein the raw material with the granularity of 80 meshes accounts for 30% and the raw material with the granularity of 40 meshes accounts for 70% according to the weight percentage), 8 parts of pore-forming agent (specifically graphite fine powder with the granularity of 1000 meshes) and 10 parts of binder (specifically water-soluble polypropylene emulsion) are stirred and mixed uniformly to obtain a mixture, and the mixture is subjected to extrusion forming and drying curing to obtain an embedded ceramic movable block, wherein the extrusion forming pressure is 8MPa, the forming temperature is 120 ℃, and the drying temperature for drying and curing is 150 ℃;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block 3 prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to obtain an impeller ceramic core wax blank, wherein the wax injection temperature of the wax injection molding is 70 ℃, the wax injection pressure is 0.6MPa, the embedded ceramic movable block 3 is embedded in an impeller blade runner of the impeller ceramic core wax blank, and metal movable blocks in the impeller ceramic core wax blank are removed;

C. and B, sintering the ceramic core wax blank of the impeller prepared in the step B, wherein in the process of sintering, the glue discharging stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at the heating speed of 1 ℃/min, the sintering stage is to keep the temperature at 1180 ℃ for 6h, a drill is used for partially cleaning the embedded ceramic movable block 3 in the impeller blade runner 2, and then compressed air is used for completing the cleaning of the rest part of the embedded ceramic movable block 3 in the impeller blade runner 2, so that the ceramic core of the impeller with the curved surface runner structure is prepared.

Example 2

A method for preparing an impeller ceramic core with a curved surface runner structure adopts a prefabricated embedded ceramic movable block 3 to replace a local metal movable block to prepare the impeller ceramic core shown in figures 1 and 2, and comprises the following steps:

A. preparing an embedded ceramic movable block: according to the weight parts, 75 parts of a ceramic material (specifically, fused corundum, wherein the raw material with the granularity of 80 meshes accounts for 30% and the raw material with the granularity of 40 meshes accounts for 70% in percentage by weight), 5 parts of a pore-forming agent (specifically, the combination of graphite fine powder and flour, the granularity of 1000 meshes) and 8 parts of a binder (specifically, water-soluble polypropylene emulsion and water-based phenolic resin) are stirred and mixed uniformly to obtain a mixture, and the mixture is subjected to extrusion forming and drying curing to obtain the embedded ceramic movable block, wherein the extrusion forming pressure is 8MPa, the forming temperature is 120 ℃, and the drying temperature for drying and curing is 150 ℃;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to obtain an impeller ceramic core wax blank, wherein the wax injection temperature of the wax injection molding is 70 ℃, the wax injection pressure is 0.6MPa, the embedded ceramic movable block is embedded in an impeller blade runner of the impeller ceramic core wax blank, and the metal movable block in the impeller ceramic core wax blank is removed;

C. and B, sintering the ceramic core wax blank of the impeller prepared in the step B, wherein in the process of sintering, the glue discharging stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at the heating speed of 1 ℃/min, the sintering stage is to keep the temperature at 1180 ℃ for 6h, a drill bit is used for partially cleaning the embedded ceramic movable block in the impeller blade flow passage, and then compressed air is used for completing the cleaning of the rest part of the embedded ceramic movable block in the impeller blade flow passage, so that the ceramic core of the impeller with the curved surface flow passage structure is prepared.

Example 3

A method for preparing an impeller ceramic core with a curved surface runner structure adopts a prefabricated embedded ceramic movable block 3 to replace a local metal movable block to prepare the impeller ceramic core shown in figures 1 and 2, and comprises the following steps:

A. preparing an embedded ceramic movable block: according to the weight parts, 85 parts of ceramic material (specifically electric melting corundum, wherein the raw material with the granularity of 80 meshes accounts for 30% and the raw material with the granularity of 40 meshes accounts for 70% in percentage by weight), 10 parts of pore-forming agent (specifically the combination of graphite fine powder, flour and millet powder, the granularity of 1000 meshes) and 12 parts of binder (specifically water-soluble polypropylene emulsion and water-based phenolic resin) are stirred and mixed uniformly to obtain a mixture, and the mixture is subjected to extrusion forming and drying curing to obtain the embedded ceramic movable block, wherein the extrusion forming pressure is 8MPa, the forming temperature is 120 ℃, and the drying temperature for drying and curing is 150 ℃;

B. preparing a ceramic core wax blank of the impeller: assembling the embedded ceramic movable block prepared in the step A in an inner cavity of a ceramic core mold to form a composite mold, and performing wax injection molding to obtain an impeller ceramic core wax blank, wherein the wax injection temperature of the wax injection molding is 70 ℃, the wax injection pressure is 0.6MPa, the embedded ceramic movable block is embedded in an impeller blade runner of the impeller ceramic core wax blank, and the metal movable block in the impeller ceramic core wax blank is removed;

C. and B, sintering the ceramic core wax blank of the impeller prepared in the step B, wherein in the process of sintering, the glue discharging stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at the heating speed of 1 ℃/min, the sintering stage is to keep the temperature at 1180 ℃ for 6h, a drill bit is used for partially cleaning the embedded ceramic movable block in the impeller blade flow passage, and then compressed air is used for completing the cleaning of the rest part of the embedded ceramic movable block in the impeller blade flow passage, so that the ceramic core of the impeller with the curved surface flow passage structure is prepared.

Example 4

Compared with the example 1, in the ceramic material of the step A, the raw materials with the granularity of 80 meshes account for 20 percent, the raw materials with the granularity of 40 meshes account for 80 percent, and the components of the rest raw materials and the preparation method are consistent with those of the example 1, so that the impeller ceramic core with the curved-surface flow channel structure is prepared.

Example 5

Compared with the embodiment 1, in the step C, in the process of sintering the ceramic core wax blank of the impeller prepared in the step B, the glue discharging stage is to heat the ceramic core wax blank of the impeller from 100 ℃ to 450 ℃ at the heating rate of 2 ℃/min, and the other raw material components and the preparation method are the same as those in the embodiment 1, so that the ceramic core of the impeller with the curved-surface flow channel structure is prepared.

Example 6

Compared with the example 1, in the step B, the temperature of the wax injection for the wax injection molding is 75 ℃, the pressure of the wax injection is 0.8MPa, and the other raw material components and the preparation method are all the same as those in the example 1, so that the impeller ceramic core with the curved surface runner structure is prepared.

Example 7

Compared with the example 1, in the step B, the temperature of the wax injection for the wax injection molding is 65 ℃, the pressure of the wax injection is 0.4MPa, and the other raw material components and the preparation method are all the same as those in the example 1, so that the impeller ceramic core with the curved surface runner structure is prepared.

Example 8

Compared with the embodiment 1, in the step C, the sintering stage is specifically that the temperature is kept at 1150 ℃ for 8 hours, and the other raw material components and the preparation method are all the same as those in the embodiment 1, so that the impeller ceramic core with the curved flow passage structure is prepared.

Example 9

Compared with the embodiment 1, in the step C, the sintering stage is specifically that the temperature is kept at 1200 ℃ for 4h, and the rest raw material components and the preparation method are all the same as those in the embodiment 1, so that the impeller ceramic core with the curved surface flow channel structure is prepared.

Example 10

Compared with the example 1, in the ceramic material of the step A, the raw materials with the granularity of 80 meshes account for 10 percent and the raw materials with the granularity of 40 meshes account for 90 percent, and the components of the rest raw materials and the preparation method are consistent with those of the example 1, so that the impeller ceramic core with the curved-surface flow channel structure is prepared.

Example 11

Compared with the embodiment 1, in the step C, in the process of sintering the ceramic core wax blank of the impeller prepared in the step B, the glue discharging stage is to heat the ceramic core wax blank of the impeller from 100 ℃ to 450 ℃ at a heating rate of 3 ℃/min, and the other raw material components and the preparation method are the same as those in the embodiment 1, so that the ceramic core of the impeller with the curved-surface flow channel structure is prepared.

Example 12

Compared with the embodiment 1, in the step A, the extrusion forming pressure is 4MPa, the forming temperature is 90 ℃, and the other raw material components and the preparation method are all the same as those in the embodiment 1, so that the ceramic core of the impeller with the curved-surface flow channel structure is prepared.

Example 13

Compared with the example 1, in the step B, the temperature of the wax injection for the wax injection molding is 70 ℃, the pressure of the wax injection is 0.9MPa, and the other raw material components and the preparation method are all the same as those in the example 1, so that the impeller ceramic core with the curved surface runner structure is prepared.

Comparative example 1

A method for preparing an impeller ceramic core with a curved flow passage structure, which is used for preparing the impeller ceramic core shown in figures 1 and 2, comprises the following steps:

A. preparing a ceramic core wax blank of the impeller: assembling the metal movable block in a ceramic core mould, and performing wax injection molding to obtain an impeller ceramic core wax blank, wherein the wax injection temperature of the wax injection molding is 70 ℃, the wax injection pressure is 0.6MPa, and then drawing out the metal movable block from an impeller blade flow passage of the impeller ceramic core wax blank;

B. and B, sintering the ceramic core wax blank of the impeller ceramic core prepared in the step A, wherein in the sintering process, the glue discharging stage is to heat the ceramic core wax blank from 100 ℃ to 450 ℃ at the heating speed of 1 ℃/min, and in the sintering stage, the ceramic core wax blank is to be insulated for 6 hours at 1180 ℃ to prepare the ceramic core of the impeller with the curved-surface flow channel structure.

The ceramic inserts of example 1 to example 13 were tested for flexural strength (flexural strength was measured by a three-point method), and the deformation of the impeller blade flow channels in the ceramic cores of the impellers of example 1 to example 13 and comparative example 1 was observed, and the results of the performance tests of the examples and comparative examples are shown in the following table:

from the test results, the ceramic cores of the impellers prepared in the embodiments 1 to 9 adopt the embedded ceramic movable block to replace the metal movable block, after wax injection molding, the embedded ceramic movable block does not need to be pulled out from the inside of the ceramic core wax blank of the impeller, the embedded ceramic movable block has high strength and does not deform in the wax injection process, the embedded ceramic movable block and the ceramic core wax blank of the impeller are directly sintered integrally, and the impeller blade flow channel in the prepared ceramic cores of the impellers has complete structure and no deformation;

example 10 when the insert ceramic movable block is prepared, the ceramic material has too many coarse particles and too few fine particles, so that the folding strength of the insert ceramic movable block is poorer than that of example 1, the smoothness of the flow channel surface after cleaning is poor, and the quality of the flow channel surface of the impeller blade in the ceramic core of the impeller is poor after sintering is completed;

in the embodiment 11, in the process of sintering the wax blank of the ceramic core of the impeller, the temperature rising speed from 100 ℃ to 450 ℃ is too fast in the glue removing stage, so that the thermal decomposition speed of the embedded ceramic movable block is accelerated, the surface of the runner has fine cracks, and the runner slightly deforms;

example 12 since the molding pressure of the extrusion molding was too low and the molding temperature was too low in the process of preparing the insert ceramic movable block, the flexural strength of the insert ceramic movable block was inferior to that of example 1 and slight deformation occurred during sintering, resulting in slight deformation of the runner of the impeller blade in the ceramic core of the impeller;

in the process of wax injection molding in the step B, the embedded ceramic movable block is slightly deformed in the wax injection process due to the overlarge wax injection pressure, so that the runner of the impeller blade in the ceramic core of the impeller is slightly deformed after sintering is completed;

the comparative example 1 directly uses the metal movable block to prepare the impeller ceramic core with the curved surface flow channel structure, when the metal movable block is pulled out from the impeller blade flow channel of the impeller ceramic core wax blank in the step A, the metal movable block can be pulled out only by using a larger external force, and the position with large flow channel bending curvature is seriously deformed, so that the prepared impeller ceramic core with the curved surface flow channel structure can not be normally used.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.