Method for eliminating gap and axial flow fan

Abstract

The invention belongs to the technical field of axial flow fans, and discloses a method for eliminating a gap and an axial flow fan. The method for eliminating the gap comprises the steps that S1, the semi-arc convex face is divided into N arc-shaped sections in the circumferential direction; s2, selecting a measuring point on each arc-shaped section; and S3, measuring the gap at each measuring point. S4, N arc segment gaskets are manufactured, the arc length of the arc segment gaskets is designed according to the arc length of the arc segment, and the thickness of the arc segment gaskets is designed according to the gap at the measuring point; and manufacturing a semi-arc gasket matched with the semi-arc convex surface. And S5, the N arc section gaskets are fixedly attached to the N arc sections in a one-to-one correspondence mode, and the semi-arc gaskets are fixedly attached to the outer surfaces of the N arc section gaskets. According to the method for eliminating the gap, the arc section gaskets with different thicknesses can be arranged according to the gap of each measuring point so as to eliminate the gap, and the semi-arc gaskets can be manufactured so as to increase the magnitude of interference, thereby further ensuring that the gap is completely eliminated, and improving the assembly precision.

Description

Technical Field

[0001] The invention relates to the technical field of axial flow fans, and in particular to a method for eliminating gaps and an axial flow fan. Background Art

[0002] The bearing box of the axial flow fan is installed in the casing, which includes an upper casing and a lower casing, and the bearing box is sandwiched between the support ribs of the upper casing and the support ribs of the lower casing. At the position where the bearing box and the support ribs of the upper casing fit together, the bearing box is provided with a semi-circular convex surface, and the support ribs of the upper casing are provided with a semi-circular concave surface. During installation, the bearing box support is installed on the support ribs of the lower casing, the upper casing is buckled on the lower casing and connected by screws, and the semi-circular concave surface of the upper casing fits with the semi-circular convex surface of the bearing box.

[0003] Due to changes in ambient temperature, fluid medium temperature, and fan shaft power, axial flow fans may experience sudden increases in vibration during operation. Sudden increases in vibration can easily cause equipment shutdown and affect the safe operation of the entire system.

[0004] However, due to processing and installation errors, there is a gap between the semicircular concave surface and the semicircular convex surface. The existence of this gap may cause the vibration to suddenly increase several times, resulting in the reduction of the stiffness of the bearing box and damage, thereby affecting the service life of the entire equipment.

[0005] In the prior art, in order to prevent the bearing box from being damaged, the stiffness of the bearing box is generally increased by welding reinforcing ribs. However, this method has limited effect in enhancing the stiffness, and the bearing box is easily deformed during the welding process, further leading to an increase in the gap. Summary of the invention

[0006] The object of the present invention is to provide a method for eliminating gaps and an axial flow fan, which can eliminate the gap between the bearing box and the upper casing to prevent the axial flow fan from being damaged due to the weakening of the bearing box stiffness due to excessive vibration during operation.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A method for eliminating gaps is applied to an axial flow fan, wherein the axial flow fan comprises a bearing box and an upper casing, wherein the bearing box is provided with a semicircular arc convex surface, and the upper casing is provided with a semicircular arc concave surface that fits the semicircular arc convex surface. The method for eliminating gaps is used to eliminate the gap between the semicircular arc convex surface and the semicircular arc concave surface, and comprises the following steps:

[0009] S1, dividing the semicircular arc convex surface into N arc segments along its circumferential direction;

[0010] S2, selecting a measuring point on each of the arc segments;

[0011] S3, measuring the gap between the semicircular arc convex surface and the semicircular arc concave surface at each measuring point;

[0012] S4, according to the arc length of each arc segment and the gap at the measuring point, making N arc segment gaskets corresponding to the arc segments one by one; and according to the arc length of the semicircular arc convex surface, making a semicircular arc gasket with a thickness of a set value;

[0013] S5, fixing and fitting the N arc segment gaskets on the N arc segments in a one-to-one correspondence, and fixing and fitting the semicircular arc gasket on the outer surfaces of the N arc segment gaskets.

[0014] As an optional solution, in step S1, the N arc segments are a first arc segment, a second arc segment, a third arc segment, a fourth arc segment and a fifth arc segment sequentially distributed along the circumferential direction of the semicircular arc convex surface, the third arc segment is centrally arranged and occupies 1 / 3 of the semicircular arc convex surface, the second arc segment and the fourth arc segment are symmetrically arranged and respectively occupy 1 / 6 of the semicircular arc convex surface, and the first arc segment and the fifth arc segment are symmetrically arranged and respectively occupy 1 / 6 of the semicircular arc convex surface;

[0015] In step S2, the measuring points include a first measuring point, a second measuring point, a third measuring point, a fourth measuring point and a fifth measuring point respectively located in the first arc segment, the second arc segment, the third arc segment, the fourth arc segment and the fifth arc segment.

[0016] As an optional scheme, in step S2, along the circumferential direction of the semicircular arc convex surface, the center of the first arc segment is selected as the first measuring point, the center of the second arc segment is selected as the second measuring point, the center of the third arc segment is selected as the third measuring point, the center of the fourth arc segment is selected as the fourth measuring point, and the center of the fifth arc segment is selected as the fifth measuring point.

[0017] As an optional solution, in step S2, the gap at the first measuring point is set to j1, the gap at the second measuring point is set to j2, the gap at the third measuring point is set to j3, the gap at the fourth measuring point is set to j4, and the gap at the fifth measuring point is set to j5;

[0018] In step S4, the N arc segment gaskets include a first arc segment gasket, a second arc segment gasket, a third arc segment gasket, a fourth arc segment gasket and a fifth arc segment gasket corresponding to the first arc segment, the second arc segment, the third arc segment, the fourth arc segment and the fifth arc segment respectively;

[0019] The thickness of the first arc segment gasket h1=(j1+j5) / 2;

[0020] The thickness of the second arc segment gasket h2=(j2+j4) / 2;

[0021] The thickness of the third arc segment gasket is h3=j3;

[0022] The thickness of the fourth arc segment gasket h4=(j2+j4) / 2;

[0023] The thickness of the fifth arc segment gasket is h5=(j1+j5) / 2.

[0024] As an optional solution, the gap j1 at the first measuring point, the gap j2 at the second measuring point, the gap j3 at the third measuring point, the gap j4 at the fourth measuring point, and the gap j5 at the fifth measuring point are all average values ​​after multiple measurements.

[0025] As an optional solution, in step S4, the N arc segment gaskets include a first arc segment gasket, a second arc segment gasket, a third arc segment gasket, a fourth arc segment gasket and a fifth arc segment gasket corresponding to the first arc segment, the second arc segment, the third arc segment, the fourth arc segment and the fifth arc segment respectively;

[0026] The arc length of the first arc segment gasket c1=πD / 12-A;

[0027] The arc length of the second arc segment gasket c2=πD / 12-A;

[0028] The arc length of the third arc segment gasket is c3=πD / 6-A;

[0029] The arc length of the fourth arc segment gasket c4=πD / 12-A;

[0030] The arc length of the fifth arc segment gasket is c5=πD / 12-A;

[0031] Wherein, D is the diameter of the semicircular arc convex surface, and A is a positive number less than or equal to 20.

[0032] As an optional solution, in step S6, the thickness h0 of the semicircular arc gasket is set within the range of 0.1 mm-0.5 mm;

[0033] The arc length c0 of the semicircular arc gasket is πD / 2-A, wherein D is the diameter of the semicircular arc convex surface, and A is a positive number less than or equal to 20.

[0034] As an optional solution, in step S3, the gap at each measuring point is measured using a lead wire method.

[0035] As an optional solution, in step S5, the arc segment gasket is glued to the corresponding arc segment, and the semicircular arc gasket is glued to the outer surfaces of N arc segment gaskets.

[0036] An axial flow fan adopts the method for eliminating the gap described in any of the above schemes to eliminate the gap between the bearing box and the upper casing.

[0037] Beneficial effects of the present invention:

[0038] The present invention provides a method for eliminating gaps, which divides a semicircular arc convex surface into N arc segments, selects measuring points on each arc segment, measures the gap, and then manufactures arc segment gaskets according to the arc length and gap of each arc segment, so that arc segment gaskets of different thicknesses can be set according to the gaps of each measuring point to eliminate the gap, and manufactures semicircular arc gaskets to increase the interference, further ensuring that the gap is completely eliminated and improving the assembly accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a hidden upper casing of an axial flow fan provided by an embodiment of the present invention;

[0040] Figure 2 is a flow chart of a method for eliminating gaps provided by an embodiment of the present invention;

[0041] Figure 3 It is a structural schematic diagram of a portion of a bearing box provided with a semicircular arc convex surface according to an embodiment of the present invention;

[0042] Figure 4 It is a structural schematic diagram of the arc segment gasket involved in the embodiment of the present invention when it is fixedly attached to the semicircular arc convex surface of the bearing box;

[0043] Figure 5 It is a schematic diagram of the structure of the arc segment gasket and the semicircular arc gasket involved in the embodiments of the present invention.

[0044] In the figure:

[0045] 1. bearing box; 11. arc segment; 111. first arc segment; 112. second arc segment; 113. third arc segment; 114. fourth arc segment; 115. fifth arc segment;

[0046] R1, first measuring point; R2, second measuring point; R3, third measuring point; R4, fourth measuring point; R5, fifth measuring point;

[0047] 2. Lower casing;

[0048] 3. Arc segment gasket; 31. First arc segment gasket; 32. Second arc segment gasket; 33. Third arc segment gasket; 34. Fourth arc segment gasket; 35. Fifth arc segment gasket;

[0049] 4. Semicircular arc gasket;

[0050] 5. Impeller components. DETAILED DESCRIPTION

[0051] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar parts or parts having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0052] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, it can be a mechanical connection or an electrical connection, it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the description of the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0054] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0055] The embodiment of the present invention provides a method for eliminating gaps, which is applied to an axial flow fan, such as Figure 1 As shown, the axial flow fan includes a bearing box 1, an upper casing, a lower casing 2 and an impeller component 5. The upper casing and the lower casing 2 are connected to each other by screws. The bearing box 1 is arranged in the upper casing and the lower casing 2. The impeller component 5 is arranged on both sides of the upper casing and the lower casing 2. At the position where the bearing box 1 and the upper casing contact, the bearing box 1 is provided with a semi-circular convex surface, and the upper casing is provided with a semi-circular concave surface. The semi-circular convex surface can fit with the semi-circular concave surface to limit the bearing box 1. However, due to processing or assembly errors, there is a gap between the semi-circular convex surface and the semi-circular concave surface. In order to eliminate the gap between the semi-circular convex surface and the semi-circular concave surface, the method of eliminating the gap is adopted to solve the above problem.

[0056] Specifically, Figure 2-Figure 5As shown, the method for eliminating the gap includes the following steps: S1, dividing the semicircular arc convex surface into N arc segments 11 along the circumferential direction. S2, selecting a measuring point on each arc segment 11. S3, measuring the gap between the semicircular arc convex surface and the semicircular arc concave surface at each measuring point; during the measurement process, the bearing box 1 is installed on the lower housing 2, and N measuring tools are respectively fixed at the N measuring points, and then the upper housing and the lower housing 2 are connected and fastened, and then the measuring tool can measure the gap at the corresponding measuring point. S4, making N arc segment gaskets 3, the arc length of the arc segment gasket 3 is designed according to the arc length of the arc segment 11, and the thickness of the arc segment gasket 3 is designed according to the gap at the measuring point; and making a semicircular arc gasket 4 matching the semicircular arc convex surface, the arc length of the semicircular arc gasket 4 is designed according to the arc length of the semicircular arc convex surface, and its thickness is a set value. S5, N arc-segment gaskets 3 are fixedly attached to N arc-shaped segments 11 in a one-to-one correspondence, and semicircular arc gaskets 4 are fixedly attached to the outer surfaces of the N arc-segment gaskets 3. When the upper shell and the lower shell are fixedly connected, the gap between the semicircular arc convex surface and the semicircular arc concave surface is eliminated by the arc-segment gasket 3 and the semicircular arc gasket 4 attached to the outer surfaces of the N arc-segment gaskets 3. By adding a semicircular arc gasket 4, an interference fit can be provided between the semicircular arc convex surface and the semicircular arc concave surface to ensure that the gap is completely eliminated.

[0057] It can be understood that the gap at each location in the entire fitted semicircular arc convex surface and semicircular arc concave surface may be different. The method of eliminating the gap is used to divide the semicircular arc convex surface into N arc segments 11, and measuring points are selected on each arc segment 11, and the gap is measured. Then, arc segment gaskets 3 are produced according to the arc length and gap of each arc segment 11, so that arc segment gaskets 3 of different thicknesses can be set according to the gaps at each measuring point to eliminate the gaps, and semicircular arc gaskets 4 are produced to increase the interference fit, thereby further ensuring that the gaps are completely eliminated and improving the assembly accuracy.

[0058] Specifically, in step S1, the N arc segments 11 include a first arc segment 111, a second arc segment 112, a third arc segment 113, a fourth arc segment 114 and a fifth arc segment 115 which are sequentially distributed along the circumferential direction of the semicircular convex surface. The third arc segment 113 is centrally arranged and occupies 1 / 3 of the semicircular convex surface. The second arc segment 112 and the fourth arc segment 114 are symmetrically arranged and respectively occupy 1 / 6 of the semicircular convex surface. The first arc segment 111 and the fifth arc segment 115 are symmetrically arranged and respectively occupy 1 / 6 of the semicircular convex surface. In step S2, the measuring points include a first measuring point R1, a second measuring point R2, a third measuring point R3, a fourth measuring point R4 and a fifth measuring point R5. The first measuring point R1, the second measuring point R2, the third measuring point R3, the fourth measuring point R4 and the fifth measuring point R5 are respectively located at the first arc segment 111, the second arc segment 112, the third arc segment 113, the fourth arc segment 114 and the fifth arc segment 115. The gap between the semicircular arc convex surface and the semicircular arc concave surface at the first measuring point R1 is set to j1, the gap between the semicircular arc convex surface and the semicircular arc concave surface at the second measuring point R2 is set to j2, the gap between the semicircular arc convex surface and the semicircular arc concave surface at the third measuring point R3 is set to j3, the gap between the semicircular arc convex surface and the semicircular arc concave surface at the fourth measuring point R4 is set to j4, and the gap between the semicircular arc convex surface and the semicircular arc concave surface at the fifth measuring point R5 is set to j5. By dividing the semicircular arc convex surface into five arc segments 11 according to the above layout, the arc segment gasket 3 is designed to be simpler and more convenient, and the requirement of eliminating the gap is met.

[0059] In order to make the selection of measuring points more reasonable and the measured gap value more representative, along the circumferential direction of the semicircular convex surface, the center of the first arc segment 111 is selected as the first measuring point R1, the center of the second arc segment 112 is selected as the second measuring point R2, the center of the third arc segment 113 is selected as the third measuring point R3, the center of the fourth arc segment 114 is selected as the fourth measuring point R4, and the center of the fifth arc segment 115 is selected as the fifth measuring point R5. By selecting the center of each arc segment 11 as the measuring point, the measurement result is more reliable.

[0060] Specifically, in step S4, the N arc segment gaskets 3 include a first arc segment gasket 31, a second arc segment gasket 32, a third arc segment gasket 33, a fourth arc segment gasket 34 and a fifth arc segment gasket 35 corresponding to the first arc segment 111, the second arc segment 112, the third arc segment 113, the fourth arc segment 114 and the fifth arc segment 115 respectively. The thickness h1 of the first arc-segment gasket 31 is equal to the thickness h5 of the fifth protective pad gasket, that is, h1=h5=(j1+j5) / 2, that is, h1 and h5 are both the average values ​​of the gap at the first measuring point R1 and the gap at the fifth measuring point R5; the h2 of the second arc-segment gasket 32 ​​is equal to the thickness h4 of the fourth arc-segment gasket 34, that is, h2=h4=(j2+j4) / 2, that is, h2 and h4 are both the average values ​​of the gap at the second measuring point R2 and the gap at the fourth measuring point R4; the thickness h3 of the third arc-segment gasket 33 is h3=j3, that is, h3 is the gap at the third measuring point R3.

[0061] Furthermore, in order to further improve the accuracy of the gap measurement, the gap j1 at the first measuring point R1, the gap j2 at the second measuring point R2, the gap j3 at the third measuring point R3, the gap j4 at the fourth measuring point R4, and the gap j5 at the fifth measuring point R5 are all average values ​​after multiple measurements. In this embodiment, three measurements can meet the requirements.

[0062] Specifically, the arc length c1 of the first arc segment gasket 31, the arc length c2 of the second arc segment gasket 32, the arc length c4 of the fourth arc segment gasket 34 and the arc length c5 of the fifth arc segment gasket 35 are all equal, that is, c1=c2=c4=c5=πD / 12-A; the arc length c3 of the third arc segment gasket 33=πD / 6-A; wherein D is the diameter of the semicircular arc convex surface, and A is a positive number less than or equal to 20 mm. By subtracting a positive number less than or equal to 20 from the arc length of the arc segment 11, the arc length of the arc segment gasket 3 obtained is smaller than the arc length of the corresponding arc segment 11, so as to ensure that the arc segment gasket 3 can be completely fitted to the corresponding arc segment 11. In this embodiment, A is 10.

[0063] Specifically, the thickness h0 of the semicircular arc gasket 4 is set within the range of 0.1mm-0.5mm, and the design of the interference is more reasonable by adding another semicircular arc gasket 4 within the range of 0.1mm-0.5mm to the outer surface of the arc segment gasket 3. In this embodiment, h0=0.3mm.

[0064] Specifically, the arc length c0 of the semicircular arc gasket 4 is πD / 2-A, that is, the arc length of the semicircular arc convex surface is subtracted by a positive number less than or equal to 20, so that the semicircular arc gasket 4 can completely fit on the semicircular arc convex surface.

[0065] Furthermore, the arc segment gasket 3 is glued to the corresponding arc segment 11, and the semicircular arc gasket 4 is glued to the outer surface of the N arc segment gaskets 3. Fixing with glue can effectively prevent the arc segment gasket 3 and the semicircular arc gasket 4 from sliding without increasing the thickness as much as possible.

[0066] After the arc segment gasket 3 and the semicircular arc gasket 4 are attached, the upper casing is hoisted onto the bearing box 1 , and the upper casing and the lower casing 2 are fixedly connected.

[0067] Optionally, in step S3, a lead wire method is used to measure the gap between the semi-circular convex surface and the semi-circular concave surface at each measuring point, that is, a lead wire is used as a measuring tool, and the lead wire is fixed at each measuring point before the upper shell is installed. Then, the upper shell is installed and fixed to the lower shell 2, and the lead wire is clamped between the semi-circular convex surface and the semi-circular concave surface, and the lead wire is flattened. The thickness of the lead wire is the value of the gap.

[0068] The embodiment of the present invention further provides an axial flow fan, which adopts the above-mentioned method for eliminating the gap to eliminate the gap between the bearing box 1 and the upper casing, thereby improving the service life of the bearing box 1 and the stability of the axial flow fan.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for eliminating gaps, characterized in that: Applied to an axial flow fan, the axial flow fan comprises a bearing box (1) and an upper casing, the bearing box (1) is provided with a semicircular arc convex surface, the upper casing is provided with a semicircular arc concave surface abutting against the semicircular arc convex surface, the method for eliminating the gap is used to eliminate the gap between the semicircular arc convex surface and the semicircular arc concave surface, and comprises the following steps: S1, dividing the semicircular arc convex surface into N arc segments (11) along its circumferential direction; S2, selecting a measuring point on each of the arc segments (11); S3, measuring the gap between the semicircular arc convex surface and the semicircular arc concave surface at each measuring point; S4, according to the arc length of each arc segment (11) and the gap at the measuring point, manufacturing N arc segment gaskets (3) corresponding to the arc segments (11) one by one; and manufacturing a semicircular arc gasket (4) with a thickness of a set value according to the arc length of the semicircular arc convex surface; S5, fixing and affixing the N arc segment gaskets (3) to the N arc segments (11) in a one-to-one correspondence, and fixing and affixing the semicircular arc gasket (4) to the outer surfaces of the N arc segment gaskets (3).

2. The method for eliminating gaps according to claim 1, characterized in that: In step S1, the N arc segments (11) are a first arc segment (111), a second arc segment (112), a third arc segment (113), a fourth arc segment (114) and a fifth arc segment (115) which are sequentially distributed along the circumferential direction of the semicircular arc convex surface, the third arc segment (113) is centrally arranged and occupies 1 / 3 of the semicircular arc convex surface, the second arc segment (112) and the fourth arc segment (114) are symmetrically arranged and respectively occupy 1 / 6 of the semicircular arc convex surface, and the first arc segment (111) and the fifth arc segment (115) are symmetrically arranged and respectively occupy 1 / 6 of the semicircular arc convex surface; In step S2, the measuring points include a first measuring point (R1), a second measuring point (R2), a third measuring point (R3), a fourth measuring point (R4) and a fifth measuring point (R5) respectively located at the first arc segment (111), the second arc segment (112), the third arc segment (113), the fourth arc segment (114) and the fifth arc segment (115).

3. The method for eliminating gaps according to claim 2, characterized in that: In step S2, along the circumferential direction of the semicircular arc convex surface, the center of the first arc segment (111) is selected as the first measuring point (R1), the center of the second arc segment (112) is selected as the second measuring point (R2), the center of the third arc segment (113) is selected as the third measuring point (R3), the center of the fourth arc segment (114) is selected as the fourth measuring point (R4), and the center of the fifth arc segment (115) is selected as the fifth measuring point (R5).

4. The method for eliminating gaps according to claim 2, characterized in that: In step S2, the gap at the first measuring point (R1) is set to j1, the gap at the second measuring point (R2) is set to j2, the gap at the third measuring point (R3) is set to j3, the gap at the fourth measuring point (R4) is set to j4, and the gap at the fifth measuring point (R5) is set to j5; In step S4, the N arc segment gaskets (3) include a first arc segment gasket (31), a second arc segment gasket (32), a third arc segment gasket (33), a fourth arc segment gasket (34) and a fifth arc segment gasket (35) corresponding to the first arc segment (111), the second arc segment (112), the third arc segment (113), the fourth arc segment (114) and the fifth arc segment (115), respectively; The thickness of the first arc segment gasket (31) is h1=(j1+j5) / 2; The thickness of the second arc segment gasket (32) is h2=(j2+j4) / 2; The thickness of the third arc segment gasket (33) is h3=j3; The thickness of the fourth arc segment gasket (34) is h4=(j2+j4) / 2; The thickness of the fifth arc segment gasket (35) is h5=(j1+j5) / 2.

5. The method for eliminating gaps according to claim 4, characterized in that: The gap j1 at the first measuring point (R1), the gap j2 at the second measuring point (R2), the gap j3 at the third measuring point (R3), the gap j4 at the fourth measuring point (R4), and the gap j5 at the fifth measuring point (R5) are all average values ​​after multiple measurements.

6. The method for eliminating gaps according to claim 2, characterized in that: In step S4, the N arc segment gaskets (3) include a first arc segment gasket (31), a second arc segment gasket (32), a third arc segment gasket (33), a fourth arc segment gasket (34) and a fifth arc segment gasket (35) corresponding to the first arc segment (111), the second arc segment (112), the third arc segment (113), the fourth arc segment (114) and the fifth arc segment (115), respectively; The arc length c1 of the first arc segment gasket (31) is =πD / 12-A; The arc length c2 of the second arc segment gasket (32) is πD / 12-A; The arc length c3 of the third arc segment gasket (33) is =πD / 6-A; The arc length c4 of the fourth arc segment gasket (34) is =πD / 12-A; The arc length c5 of the fifth arc segment gasket (35) is πD / 12-A; Wherein, D is the diameter of the semicircular arc convex surface, and A is a positive number less than or equal to 20.

7. The method for eliminating gaps according to claim 1, characterized in that: In step S6, the thickness h0 of the semicircular arc gasket (4) is set within the range of 0.1 mm to 0.5 mm; The arc length c0 of the semicircular arc gasket (4) is πD / 2-A, wherein D is the diameter of the semicircular arc convex surface, and A is a positive number less than or equal to 20.

8. The method for eliminating gaps according to claim 1, characterized in that: In step S3, the gap at each measuring point is measured using a lead wire method.

9. The method for eliminating gaps according to claim 1, characterized in that: In step S5, the arc segment gasket (3) is bonded to the corresponding arc segment (11) by glue, and the semicircular arc gasket (4) is bonded to the outer surface of N arc segment gaskets (3) by glue.

10. Axial flow fan, characterized in that: The gap elimination method described in any one of claims 1 to 9 is used to eliminate the gap between the bearing box (1) and the upper casing.

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