Method for eliminating linear segregation defect of ZL205A conical rotary body casting

Abstract

The invention relates to a method for eliminating the linear segregation defect of a ZL205A conical rotary body casting, belongs to the technical field of aluminum alloy casting, and solves the problem that linear segregation generated in the casting forming process of the ZL205A conical rotary body casting can only be reduced but cannot be eliminated in the prior art. According to the new thought that the segregation defect is eliminated by improving the casting structure, the cross-shaped grid ribs are additionally arranged at the bottom of the casting, the wall thickness is evenly increased on the inner side of the large end of the casting, stress concentration during casting solidification can be reduced, the rigidity of the casting and the heat crack resistance during solidification can be improved, and the linear segregation defect of the rotary body casting is eliminated; and the method is simple in process, low in cost and high in efficiency, and has better flexibility and stability.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy casting, in particular to a method for eliminating linear segregation defects of a ZL205A conical body of revolution casting. Background Art

[0002] Weight reduction, high reliability, low cost and short manufacturing cycle are the goals of modern weapon equipment development. Aluminum alloys, with their advantages of light weight and high strength and the advancement of modern aluminum alloy casting technology, have made various large-scale, integral aluminum alloy castings more and more widely used in aerospace. Conical rotating body structure is one of the common structures of this type of castings. This type of casting has high requirements for performance and internal quality, and ZL205A alloy is generally used.

[0003] During the casting process of ZL205A conical gyrating body castings, the linear segregation defect rate is very high, which has become the biggest obstacle to the large-scale application of ZL205A alloy castings in aerospace. Traditional methods to solve linear segregation involve multiple aspects such as casting process, alloy composition optimization, smelting method adjustment, and heat treatment process adjustment. However, through actual engineering verification, these process measures can only reduce but not completely eliminate linear segregation, and the adjustment of casting process, alloy composition optimization, smelting method adjustment, and heat treatment process adjustment leads to complex casting manufacturing process, low production efficiency, and high manufacturing cost. Therefore, there is an urgent need for a simple and direct method that can effectively eliminate the linear segregation defects of ZL205A conical gyrating body castings. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a method for effectively eliminating linear segregation defects of ZL205A conical body of revolution castings, so as to solve at least one of the problems of conventional methods for solving linear segregation in the prior art, such as casting process, alloy composition optimization, smelting method adjustment, and heat treatment process adjustment, which can only reduce but not eliminate linear segregation, and have complex processes, low production efficiency, and high manufacturing costs.

[0005] On the one hand, the present invention provides a method for eliminating linear segregation defects of a ZL205A conical body of revolution casting, comprising the following steps:

[0006] S1. Change the original mold structure to increase the wall thickness on the inside of the big end of the casting and form the cross grid ribs required for the casting;

[0007] S2. Using the prepared mold for molding and casting, a casting is obtained in which the inner wall thickness of the large end is increased and a cross grid rib is formed on the inner side;

[0008] S3. Remove the increased wall thickness on the inner side of the large end and the inner cross grid ribs to obtain the target ZL205A conical rotating body casting.

[0009] Furthermore, in S1, changing the original mold structure includes:

[0010] S11, setting a cavity thickening portion inside the big end of the mold to cast and form the thickening portion of the casting inside the big end of the casting;

[0011] S12. A corresponding groove is provided at the thickened portion of the cavity on the inner side of the large end of the mold to cast and form the cross grid ribs required for the casting.

[0012] Furthermore, in S3, a target ZL205A conical body of revolution casting is obtained, the bottom diameter of which is 500-1000 mm; the side wall thickness is a, and the range of a is 18-26 mm.

[0013] Furthermore, in S11, the cavity thickening portion is provided on the inner side of the big end of the mold, which refers to adjusting the mold design, and providing the cavity thickening portion on the inner side of the big end of the mold according to the required increase in wall thickness on the inner side of the big end of the casting, i.e., the thickened portion of the casting; the thickness of the thickened portion of the casting refers to the thickness δ of its bottom, and δ=(1.5~2)×a.

[0014] Furthermore, in S12, the groove is formed on the surface of the thickened portion of the cavity inside the large end of the mold, and a circle of grooves corresponding to the cross grid ribs formed in the casting is machined.

[0015] Furthermore, the cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection.

[0016] Furthermore, in S3, the width of a single rib of the cross grid rib is A, wherein A=(0.5-1)×a, where a is the thickness of the side wall of the conical body of revolution casting; the spacing between two adjacent parallel ribs of the cross grid rib is d, wherein d=80-100 mm; and the height of the cross grid rib is h, wherein h=5-8 mm.

[0017] Further, in S2, after pouring the casting, a casting with a changed structure is obtained, including a casting body and a changed structure part; the casting body is a ZL205A conical rotating body; the changed structure part is located at the bottom of the casting; the changed structure part includes a thickened casting part and a cross grid rib; the thickened casting part has a right triangle cross-section, is arranged on the inner side of the large end of the casting body, and is continuously and evenly distributed in a circle along the circumferential direction of the inner side of the large end of the casting; the cross grid ribs are arranged in a circle along the circumferential direction of the inner side of the large end of the casting, and are laid flat on the outer surface of the thickened part 2 of the casting; the cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection; the outer surface of the thickened part of the casting is connected to the cross grid ribs.

[0018] Furthermore, in S3, the method for removing the increased wall thickness on the inner side of the large end and the cross grid ribs on the inner side includes cleaning and cutting, and finally obtaining a qualified ZL205A conical rotating body casting.

[0019] On the other hand, the present invention provides a ZL205A conical rotating body casting which eliminates linear segregation defects and is prepared by the method described above.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] 1. A novel and effective method for eliminating linear segregation defects in ZL205A conical gyrating body castings is proposed. Different from the traditional method of solving linear segregation involving casting process, alloy composition optimization, smelting method adjustment, heat treatment process adjustment, etc., the present invention adopts a new idea of ​​reducing segregation defects by improving the casting structure. The wall thickness is uniformly increased on the inner side of the large end of the casting to change the bottom structure of the casting, and cross grid ribs are added at the changed structure to reduce stress concentration during casting solidification, increase the rigidity of the casting and its resistance to thermal cracking during solidification, significantly eliminate linear segregation defects in gyrating body castings, and greatly improve the first-time qualified rate of castings.

[0022] 2. The method for eliminating linear segregation defects of ZL205A conical gyrating body castings of the present invention is simple, direct, low-cost and highly efficient. The present invention can reduce segregation defects by optimizing the structure at the casting design stage, and can achieve the purpose of completely eliminating linear segregation without the need for additional equipment and complex process steps. The scrap rate and subsequent processing costs are reduced, and the optimized casting structure usually has better fluidity and shrinkage compensation, which helps to reduce casting defects and improve production efficiency.

[0023] 3. The method for eliminating linear segregation defects of ZL205A conical gyrating body castings of the present invention is highly flexible. By analyzing the solidification process of the castings, the present invention can specifically adjust the casting structure to minimize segregation, can adapt to different types of castings and alloys, and flexibly deal with different segregation problems by adjusting structural parameters to improve the quality of the castings.

[0024] 4. The method for eliminating linear segregation defects in the ZL205A conical gyrating body casting of the present invention has strong durability and stability. Once the casting structure is optimized, the effect of reducing segregation will exist for a long time. Compared with the process parameters that need to be continuously monitored and adjusted, it has higher durability. In addition, structural optimization fundamentally reduces the cause of segregation, so even if the process parameters fluctuate within a certain range, it will not have a significant impact on segregation, and has better stability.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 It is a cross-sectional view of a conical body of revolution casting;

[0028] Figure 2 This is a cross-sectional view of a casting after the structure of the present invention is changed;

[0029] Figure 3 It is an enlarged view of the structural change part of the casting of the present invention;

[0030] Figure 4 It is a schematic plan view of the cross grid rib structure of the casting of the present invention;

[0031] Figure 5 This is an X-ray inspection diagram of a cross section of a casting according to Example 1 of the present invention;

[0032] Figure 6 This is an X-ray inspection diagram of the cross section of the casting of Comparative Example 1 of the present invention;

[0033] Figure 7 This is an X-ray inspection diagram of the cross section of the casting of Comparative Example 3 of the present invention;

[0034] Figure 8This is an X-ray inspection diagram of the cross section of the casting of Comparative Example 4 of the present invention;

[0035] Fig. 9 This is an X-ray inspection diagram of the cross section of the casting of Comparative Example 5 of the present invention.

[0036] Reference numerals:

[0037] 1- casting body; 2- thickened part of casting; 3- cross grid ribs; 4- changed structural part. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0039] On the one hand, a specific embodiment of the present invention discloses a method for eliminating linear segregation defects of a ZL205A conical body of revolution casting, comprising the following steps:

[0040] S1. Change the original mold structure to increase the wall thickness on the inside of the big end of the casting and form the cross grid ribs required for the casting;

[0041] S2. Using the prepared mold for molding and casting, a casting is obtained in which the inner wall thickness of the large end is increased and a cross grid rib is formed on the inner side;

[0042] S3. Remove the increased wall thickness on the inner side of the large end and the inner cross grid ribs to obtain the target ZL205A conical rotating body casting.

[0043] Furthermore, before S1, it also includes a properly designed pouring system, and the properly designed pouring system includes a designed cross runner, a gap runner and a chiller.

[0044] Existing methods for solving linear segregation involve multiple aspects such as casting process, alloy composition optimization, smelting method adjustment, and heat treatment process adjustment. However, these process measures can only reduce but not completely eliminate linear segregation, and the process is complex, the production efficiency is low, and the manufacturing cost is high. The present invention adopts a new idea to eliminate segregation defects by improving the structure of the casting, adding cross grid ribs at the bottom of the casting, and uniformly increasing the wall thickness on the inner side of the large end of the casting, which can reduce stress concentration during solidification of the casting, increase the rigidity of the casting and the resistance to thermal cracking during solidification, eliminate linear segregation defects of the rotating body casting, and greatly improve the first-time qualified rate of the casting. The method and process are simple, low cost, high efficiency, and have better flexibility and stability.

[0045] Further, in S1, changing the original mold structure includes:

[0046] S11, setting a cavity thickening portion inside the big end of the mold to cast and form a thickening portion 2 of the casting inside the big end of the casting;

[0047] S12. A corresponding groove is provided at the thickened portion of the cavity on the inner side of the large end of the mold to cast and form the cross grid ribs required for the casting.

[0048] The cone-shaped rotating body casting prepared by the above method has a bottom diameter of 500 to 1000 mm and a side wall thickness a, wherein a ranges from 18 to 26 mm. Figure 1 As shown, it is a conical rotating body structure.

[0049] When the diameter is greater than 1000mm, it is easy to cause a large temperature gradient and heat node in the solidification process of the casting, thereby increasing the risk of segregation and shrinkage defects; when the diameter is less than 500mm, it cannot provide sufficient mechanical properties to meet the load-bearing requirements of conical gyratory castings in practical applications. Therefore, the present invention is mainly aimed at ZL205A conical gyratory castings with a bottom diameter of 500 to 1000mm.

[0050] Specifically, in S11, the thickened cavity portion is provided inside the large end of the mold, which means adjusting the mold design according to the required increase in the wall thickness inside the large end of the casting, i.e., the thickened portion 2 of the casting, such as Figure 2 and Figure 3 As shown, a cavity thickening portion is provided on the inner side of the large end of the mold; the thickness of the casting thickening portion 2 refers to the thickness δ of its bottom, as shown in FIG. Figure 3 As shown, the δ=(1.5~2)×a.

[0051] Specifically, the present invention adds a circle of continuous triangular-section and uniformly distributed cavities in the circumferential direction of the inner side of the large end of the mold to adapt to the change of the wall thickness of the casting. Through the adjustment of the mold structure, when the casting is cast using the mold, the wall thickness can be increased on the inner side of the large end of the casting, the solidification temperature gradient of the corresponding position of the casting can be improved, so that a reasonable solidification sequence is formed there, and segregation can be avoided.

[0052] Specifically, the optimal thickness of the thickened part can be determined by finite element analysis and process simulation to achieve the optimization of casting design and the rationalization of process. The optimal thickness is taken as the δ value. Generally, the δ value is in the range of (1.5~2)×a.

[0053] Specifically, in S12, the groove is a circle of grooves corresponding to the cross grid ribs of the casting formed on the surface of the thickened part of the cavity inside the large end of the mold. By adjusting the mold structure, the cross grid ribs 3 of the casting can be formed when the casting is cast using the mold. The specific structure can be referred to Figure 2 and Figure 3The protruding grid portion on the surface of the circumferential casting thickened portion 2, namely the cross grid rib 3, can change the stress distribution during solidification, increase the rigidity of the casting and the resistance to thermal cracking during solidification, and eliminate the linear segregation defects of the rotating body casting.

[0054] Furthermore, the cross grid ribs are composed of two groups of mutually perpendicular ribs, such as Figure 4 As shown, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection.

[0055] Furthermore, if Figure 4 As shown, the width of a single rib of the cross grid rib is A, wherein A=(0.5-1)×a, where a is the thickness of the side wall of the conical body of revolution casting; the spacing between two adjacent parallel ribs of the cross grid rib 3 is d, wherein d=80-100 mm; the height of the cross grid rib 3 is h, wherein h=5-8 mm.

[0056] Specifically, if the width of the rib is too wide, it is easy to cause uneven cooling and shrinkage stress during the casting process, thereby causing cracks and deformation. In order to ensure the structural strength and rigidity of the casting, improve the bearing capacity and anti-deformation ability of the casting, and achieve uniform cooling and reduce casting defects, the present invention sets the width A within the range of (0.5-1)×a.

[0057] Specifically, the specific value of the rib spacing d can be adjusted according to the use environment and stress conditions of the casting. Generally, the higher the load requirement, the smaller the d value needs to be, so as to improve the local rigidity and strength. In addition, considering that a smaller spacing will increase the difficulty of casting and easily lead to casting defects, for castings with a wall thickness of 18 to 26 mm, the present invention sets the spacing d at 80 to 100 mm to avoid insufficient strength in local areas of the casting.

[0058] Furthermore, considering the stability of the structure, in order to make the grid ribs play a better supporting role in the casting, the angle between two crossed ribs of the cross grid rib 3 is set to 90°.

[0059] Further, in S2, the casting obtained after pouring is a casting with a changed structure, and its schematic diagram is as follows Figure 2 As shown, it includes a casting body 1 and a changed structure part 4; the casting body 1 is a ZL205A conical rotating body; the changed structure part 4 is located at the bottom of the casting; the changed structure part 4 includes a casting thickened part 2 and a cross grid rib 3; the casting thickened part 2 has a right triangle cross section, is arranged on the inner side of the large end of the casting body 1, and is continuously and uniformly distributed in a circle along the circumferential direction of the inner side of the large end of the casting; the cross grid rib 3, as shown Figure 2 and Figure 3As shown, it is a grid protruding from the surface of the circumferential casting thickening part 2, and its plane schematic diagram is as follows Figure 4 As shown, it is composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The outer surface of the thickened portion 2 of the casting is connected to the cross grid rib 3.

[0060] Furthermore, in S3, the method for removing the increased wall thickness on the inner side of the large end and the cross grid ribs on the inner side includes cleaning and cutting, and finally obtaining a qualified ZL205A conical rotating body casting.

[0061] Specifically, after the casting is demoulded, the sand, molding sand and other impurities on the surface of the casting are first cleaned. Then the unnecessary parts of the casting, such as runners, risers, extra protrusions or grooves, are cut and removed. At this time, the cross grid ribs and the thickened part of the casting can be cut and removed together on the inside of the big end of the casting. Since this part itself is the part added on the inside of the big end of the casting, it will not affect the size of the casting after removal, so a qualified casting can be obtained.

[0062] The obtained ZL205A conical body of revolution casting combines the advantages of the S1 casting mold structure change. After X-ray detection, it can significantly eliminate the linear segregation defects of the body of revolution casting and greatly improve the qualified rate of the casting.

[0063] On the other hand, the present invention also provides a ZL205A conical rotating body casting which eliminates the linear segregation defect, and the casting is prepared by the above method.

[0064] Furthermore, no obvious density change or discontinuity was found in the ZL205A conical body of revolution casting of the present invention, and no linear or strip-shaped density abnormality area appeared, that is, no linear segregation defect appeared, after X-ray detection.

[0065] This embodiment provides a new idea for eliminating segregation defects by optimizing the structure of ZL205A conical gyroscope castings, which solves the problem that the prior art can only reduce but not eliminate the linear segregation problem of ZL205A conical gyroscope castings during the casting process. The segregation defects can be reduced by optimizing the structure in the casting design stage, and the linear segregation can be completely eliminated without the need for additional equipment and complex process steps. The method is simple in process, low in cost and high in efficiency, and has good application prospects.

[0066] The present invention is further described below with reference to the specification using examples, but the examples are only used for the present invention and are not intended to limit the present invention.

[0067] Example 1

[0068] A method for eliminating linear segregation defects of a ZL205A conical body of revolution casting comprises the following steps:

[0069] S1. The target casting is a ZL205A conical rotating body, whose side wall thickness is 18mm. Its bottom diameter is 500mm. Based on this mold, the mold structure is changed, and a circle of continuous triangular cross-section and uniformly distributed cavity is added in the circumferential direction of the inner side of the large end of the mold, that is, the thickened part of the cavity. The thickness of the bottom of the thickened part is 30mm. Through the adjustment of the casting mold structure, the wall thickness can be increased on the inner side of the large end of the casting when the casting is cast using the mold.

[0070] S2. Set corresponding grooves at the place where the mold structure is changed: a circle of grooves corresponding to the cross grid ribs of the casting is processed on the surface of the thickened part of the cavity inside the large end of the mold (the height of the cross grid ribs is 5mm, and it consists of two groups of mutually perpendicular ribs, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib is 10mm, and the spacing between two adjacent parallel ribs is 80mm). By adjusting the mold structure, the cross grid ribs 3 of the casting can be formed when the casting is cast using the mold. The specific structure can be referred to Figure 2 and Figure 3 .

[0071] S3, using the prepared mold to shape and pour the casting to obtain a casting with a changed structure, the structure of which is as follows Figure 2 As shown. It includes a casting body 1 and a changed structure part 4; the casting body 1 is a ZL205A conical rotating body, and its side wall thickness is 18mm. The diameter of its bottom is 500mm; the changed structure part 4 is located at the bottom of the casting; the changed structure part 4 includes a casting thickened part 2 and a cross grid rib 3; the casting thickened part 2 has a right triangle cross-section, which is arranged on the inner side of the large end of the casting body 1, and is continuously and evenly distributed along the circumferential direction of the inner side of the large end of the casting. The thickness of the thickened part refers to the thickness δ of its bottom, δ=30mm; the cross grid rib 3 has a height of 5mm, is distributed along the circumferential direction of the inner side of the large end of the casting, and is laid flat on the outer surface of the casting thickened part 2. Its structural plane diagram is shown as follows Figure 4 As shown, the cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib 3 is 10 mm. The spacing between two adjacent parallel ribs of the cross grid rib 3 is 80 mm. The angle between the two intersecting ribs of the cross grid rib 3 is 90°. The outer surface of the thickened portion 2 of the casting is connected to the cross grid rib 3.

[0072] S4, post-processing such as cleaning and cutting to remove the cross grid ribs and the thickened part of the casting to obtain the ZL205A conical rotating body casting.

[0073] Test results:

[0074] The optimized ZL205A conical rotating body casting was tested by X-ray, and the results are as follows: Figure 5 As shown in the figure, the internal structure of the casting is uniform, there is no obvious density change or discontinuity, and no linear or strip-shaped density abnormal area appears, indicating that the linear segregation defect of the casting has been eliminated.

[0075] Example 2

[0076] A method for eliminating linear segregation defects of a ZL205A conical body of revolution casting comprises the following steps:

[0077] S1. The target casting is a ZL205A conical rotating body, whose side wall thickness is 24mm. Its bottom diameter is 800mm. Based on this mold, the mold structure is changed, and a circle of continuous triangular cross-section and evenly distributed cavities is added in the circumferential direction of the inner side of the large end of the mold. The thickness of the bottom of the thickened part of the cavity is 40mm. Through the adjustment of the casting mold structure, the wall thickness can be increased on the inner side of the large end of the casting when the casting is cast using the mold.

[0078] S2. Set corresponding grooves at the place where the mold structure is changed: a circle of grooves corresponding to the cross grid ribs of the casting is processed on the surface of the thickened part of the cavity inside the large end of the mold (the height of the cross grid ribs is 7mm, and it consists of two groups of mutually perpendicular ribs, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib is 20mm, and the spacing between two adjacent parallel ribs is 90mm). By adjusting the mold structure, the cross grid ribs 3 of the casting can be formed when the casting is cast using the mold. The specific structure can be referred to Figure 2 and Figure 3 .

[0079] S3, using the prepared mold to shape and pour the casting to obtain a casting with a changed structure, the structure of which is as follows Figure 2As shown. It includes a casting body 1 and a changed structure part 4; the casting body 1 is a ZL205A conical rotating body, and its side wall thickness is 24mm. The diameter of its bottom is 800mm; the changed structure part 4 is located at the bottom of the casting; the changed structure part 4 includes a casting thickened part 2 and a cross grid rib 3; the casting thickened part 2 has a right triangle cross-section, which is arranged on the inner side of the large end of the casting body 1, and is continuously and evenly distributed along the circumferential direction of the inner side of the large end of the casting. The thickness of the thickened part refers to the thickness δ of its bottom, δ=40mm; the cross grid rib 3 has a height of 7mm, is distributed along the circumferential direction of the inner side of the large end of the casting, and is laid flat on the outer surface of the casting thickened part 2. Its structural plane diagram is shown as follows Figure 4 As shown, the cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib 3 is 20 mm. The spacing between two adjacent parallel ribs of the cross grid rib 3 is 90 mm. The angle between the two intersecting ribs of the cross grid rib 3 is 90°. The outer surface of the thickened portion 2 of the casting is connected to the cross grid rib 3.

[0080] S4, post-processing such as cleaning and cutting to remove the cross grid ribs and the thickened part of the casting to obtain the ZL205A conical rotating body casting.

[0081] Test results:

[0082] The optimized ZL205A conical rotor casting was subjected to X-ray inspection, and the results were similar to those of Example 1. The internal structure of the casting was uniform, without obvious density changes or discontinuities, and no linear or strip-shaped density abnormal areas appeared, indicating that the linear segregation defects of the casting were eliminated.

[0083] Example 3

[0084] A method for eliminating linear segregation defects of a ZL205A conical body of revolution casting comprises the following steps:

[0085] S1. The target casting is a ZL205A conical rotating body, whose side wall thickness is 26mm. Its bottom diameter is 1000mm. Based on this mold, the mold structure is changed, and a circle of continuous triangular cross-section and evenly distributed cavities is added in the circumferential direction of the inner side of the large end of the mold. The thickness of the bottom of the thickened part of the cavity is 45mm. Through the adjustment of the casting mold structure, the wall thickness can be increased on the inner side of the large end of the casting when the casting is cast using the mold.

[0086] S2. Set corresponding grooves at the place where the mold structure is changed: a circle of grooves corresponding to the cross grid ribs of the casting is processed on the surface of the thickened part of the cavity inside the large end of the mold (the height of the cross grid ribs is 8mm, and it consists of two groups of mutually perpendicular ribs, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib is 20mm, and the spacing between two adjacent parallel ribs is 100mm). By adjusting the mold structure, the cross grid ribs 3 of the casting can be formed when the casting is cast using the mold. The specific structure can be referred to Figure 2 and Figure 3 .

[0087] S3, using the prepared mold to shape and pour the casting to obtain a casting with a changed structure, the structure of which is as follows Figure 2 As shown. It includes a casting body 1 and a changed structure part 4; the casting body 1 is a ZL205A conical rotating body, and its side wall thickness is 26mm. The diameter of its bottom is 1000mm; the changed structure part 4 is located at the bottom of the casting; the changed structure part 4 includes a casting thickened part 2 and a cross grid rib 3; the casting thickened part 2 has a right triangle cross-section, which is arranged on the inner side of the large end of the casting body 1, and is continuously and evenly distributed along the circumferential direction of the inner side of the large end of the casting. The thickness of the thickened part refers to the thickness δ of its bottom, δ=45mm; the cross grid rib 3 has a height of 8mm, is distributed along the circumferential direction of the inner side of the large end of the casting, and is laid flat on the outer surface of the casting thickened part 2. Its structural plane diagram is shown as follows Figure 4 As shown, the cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection. The width of a single rib of the cross grid rib 3 is 20 mm. The spacing between two adjacent parallel ribs of the cross grid rib 3 is 100 mm. The angle between the two intersecting ribs of the cross grid rib 3 is 90°. The outer surface of the thickened portion 2 of the casting is connected to the cross grid rib 3.

[0088] S4, post-processing such as cleaning and cutting to remove the cross grid ribs and the thickened part of the casting to obtain the ZL205A conical rotating body casting.

[0089] Test results:

[0090] The optimized ZL205A conical rotor casting was subjected to X-ray inspection, and the results were similar to those of Example 1. The internal structure of the casting was uniform, without obvious density changes or discontinuities, and no linear or strip-shaped density abnormal areas appeared, indicating that the linear segregation defects of the casting were eliminated.

[0091] Comparative Example 1

[0092] The only difference from Example 1 is that step (2) is missing, that is, no cross grid ribs are added.

[0093] Test results:

[0094] The ZL205A conical rotor casting of this comparative example was subjected to X-ray inspection, and the results are as follows: Figure 6 As shown in the figure, a white line similar to the crack morphology appears, indicating the occurrence of linear segregation defects. This may be because although the solidification temperature gradient at this location is improved by adjusting the thickened part structure, the stress distribution during the solidification of the casting is still not improved, resulting in a small amount of linear segregation defects.

[0095] Comparative Example 2

[0096] The only difference from Example 1 is that step (1) is missing, that is, the thickening portion is missing.

[0097] Test results:

[0098] The X-ray test results of the ZL205A conical rotor casting of this comparative example are also similar to those of Figure 6 Similarly, a white line similar to the crack morphology appears in the figure, indicating the occurrence of linear segregation defects. This may be because although the stress distribution of the casting during solidification is improved by adjusting the cross rib structure, the solidification temperature gradient at this location is still not improved, resulting in a small amount of linear segregation defects.

[0099] Comparative Example 3

[0100] The only difference from Example 1 is that the bottom diameter of the conical rotor casting is 1200 mm.

[0101] Test results:

[0102] The ZL205A conical rotor casting of this comparative example was subjected to X-ray inspection, and the results are as follows: Fig. 9 As shown in the figure, a white line similar to the crack morphology appears, indicating the occurrence of linear segregation defects. This is because the diameter of the casting is too large, resulting in large shrinkage internal stress in the casting, which exceeds the tensile strength at the lower end of the casting.

[0103] Comparative Example 4

[0104] The only difference from Example 1 is that the specific value of the thickness δ of the thickened portion of the casting is 25 mm, which is not within the range of (1.5-2)×a.

[0105] Test results:

[0106] The ZL205A conical rotor casting of this comparative example was subjected to X-ray inspection, and the results are as follows: Figure 8 As shown in the figure, a line similar to the crack morphology appears at the big end of the casting, indicating that there is a linear segregation defect at the big end of the casting. This is because the big end of the casting is thick and the solidification time in this area is long, resulting in segregation defects in this area.

[0107] Comparative Example 5

[0108] The only difference from Example 1 is that the specific value of the width A of a single rib of the cross grid rib is 8 mm, which is not within the range of (0.5-1)×a.

[0109] Test results:

[0110] The ZL205A conical rotor casting of this comparative example was subjected to X-ray inspection, and the results are as follows: Fig. 9 As shown in the figure, a white line similar to the crack morphology appears, indicating that a linear segregation defect has occurred. This may be due to the fact that the width A of the rib is not wide enough, the strength and stiffness of this part are not enough, resulting in segregation defects in this part during the solidification process.

[0111] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for eliminating linear segregation defects of ZL205A conical body of revolution casting, characterized in that: The following steps are involved: S1. Change the original mold structure to increase the wall thickness on the inside of the big end of the casting and form the cross grid ribs required for the casting; S2. Using the prepared mold for molding and casting, a casting is obtained in which the inner wall thickness of the large end is increased and a cross grid rib is formed on the inner side; S3. Remove the increased wall thickness on the inner side of the large end and the inner cross grid ribs to obtain the target ZL205A conical rotating body casting.

2. The method according to claim 1, characterized in that In S1, the changes to the original mold structure include: S11, setting a cavity thickening portion inside the big end of the mold to cast and form the thickening portion of the casting inside the big end of the casting; S12. A corresponding groove is provided at the thickened portion of the cavity on the inner side of the large end of the mold to cast and form the cross grid ribs required for the casting.

3. The method according to claim 1, characterized in that In S3, the target ZL205A conical rotating body casting is obtained, the diameter of the bottom of which is 500-1000 mm; the thickness of the side wall is a, and the range of a is 18-26 mm.

4. The method according to claim 2 or 3, characterized in that: In S11, the cavity thickening portion is provided on the inner side of the big end of the mold, which refers to adjusting the mold design, and providing the cavity thickening portion on the inner side of the big end of the mold according to the required increase in wall thickness on the inner side of the big end of the casting, i.e., the thickened portion of the casting; the thickness of the thickened portion of the casting refers to the thickness δ of its bottom, and δ=(1.5~2)×a.

5. The method according to claim 2, characterized in that: In S12, the groove is formed on the surface of the thickened part of the cavity inside the large end of the mold, and a circle of grooves corresponding to the cross grid ribs formed in the casting is machined.

6. The method according to claim 5, characterized in that The cross grid ribs are composed of two groups of mutually perpendicular ribs, one group extending in one direction at an inclination of 45°, and the other group extending perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection.

7. The method according to claim 6, characterized in that In S3, the width of a single rib of the cross grid rib is A, wherein A=(0.5-1)×a, where a is the thickness of the side wall of the conical body of revolution casting; the spacing between two adjacent parallel ribs of the cross grid rib is d, wherein d=80-100 mm; the height of the cross grid rib is h, wherein h=5-8 mm.

8. The method according to claim 1, characterized in that In S2, after pouring the casting, a casting with a changed structure is obtained, which includes a casting body and a changed structure part; the casting body is a ZL205A conical rotating body; the changed structure part is located at the bottom of the casting; the changed structure part includes a thickened part of the casting and a cross grid rib; the thickened part of the casting has a right triangle cross-section, is arranged on the inner side of the large end of the casting body, and is continuously and evenly distributed in a circle along the circumferential direction of the inner side of the large end of the casting; the cross grid rib is arranged along the circumferential direction of the inner side of the large end of the casting, and is laid flat on the outer surface of the thickened part 2 of the casting; the cross grid rib is composed of two groups of mutually perpendicular ribs, one group extends in one direction at an inclination of 45°, and the other group extends perpendicular to the first group at an inclination of 45°, forming a cross-shaped intersection; the outer surface of the thickened part of the casting is connected to the cross grid rib.

9. The method according to claim 1, characterized in that: In S3, the method of removing the increased wall thickness on the inner side of the large end and the cross grid ribs on the inner side includes cleaning and cutting, and finally obtaining a qualified ZL205A conical rotating body casting.

10. A ZL205A conical body of revolution casting with linear segregation defects eliminated, characterized in that: Prepared by the method described in any one of claims 1 to 9.

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