阅读说明：本技术 一种带有环形凹槽结构的中管以及装入滚珠轴承的工艺 (Middle pipe with annular groove structure and process for installing ball bearing ) 是由 贾自周 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种带有环形凹槽结构的中管,包括中管,所述中管装设在静叶轮毂内部,所述中管一端通过粘结剂粘结固定装设有第一滚珠轴承,另一端通过粘结剂粘结固定装设有第二滚珠轴承,所述中管一端设有第一径向支撑圆环面,另一端设有第二径向支撑圆环面,所述第一径向支撑圆环面设有第一环形凹槽,所述第一环形凹槽的高度高于第一滚珠轴承的高度,所述第二径向支撑圆环面设有第二环形凹槽,所述第二环形凹槽的高度高于第二滚珠轴承的高度,本发明提高了组装后两个滚珠轴承的同心度,提升了风扇的可靠度和寿命。(The invention discloses a middle pipe with an annular groove structure, which comprises a middle pipe, wherein the middle pipe is arranged in a static impeller hub, one end of the middle pipe is fixedly provided with a first ball bearing through bonding agent, the other end of the middle pipe is fixedly provided with a second ball bearing through bonding agent, one end of the middle pipe is provided with a first radial supporting circular ring surface, the other end of the middle pipe is provided with a second radial supporting circular ring surface, the first radial supporting circular ring surface is provided with a first annular groove, the height of the first annular groove is higher than that of the first ball bearing, the second radial supporting circular ring surface is provided with a second annular groove, and the height of the second annular groove is higher than that of the second ball bearing.)

1. The middle pipe with an annular groove structure is characterized by comprising a middle pipe (3), the middle pipe (3) is arranged in the static impeller hub (1), one end of the middle pipe (3) is fixedly provided with a first ball bearing (41) by bonding with an adhesive, the other end of the middle pipe is fixedly provided with a second ball bearing (42) by bonding with an adhesive, one end of the middle pipe (3) is provided with a first radial supporting ring surface (32), the other end is provided with a second radial supporting ring surface (34), the first radial support torus (32) is provided with a first annular groove (61), the height of the first annular groove (61) is higher than the height of the first ball bearing (41), the second radial support torus (34) is provided with a second annular groove (62), the height of the second annular groove (62) is higher than the height of the second ball bearing (42).

2. The middle pipe with an annular groove structure as claimed in claim 1, wherein the impeller hub (1) is installed inside the outer frame (2).

3. The middle tube with an annular groove structure as claimed in claim 1, wherein a first open communication chamber for containing an adhesive is formed among the first annular groove (61), the first ball bearing (41) and the middle tube (3); and a second open communication chamber for containing the adhesive is formed among the second annular groove (62), the second ball bearing (42) and the middle pipe (3).

4. The middle pipe with an annular groove structure as claimed in claim 1, wherein the middle pipe (3) is further provided with a first axial supporting ring end face (31) at one end and a second axial supporting ring end face (33) at the other end, the first ball bearing (41) has a height H1, the first radial supporting ring face (32) has a height H2, and the height from the top of the first annular groove (61) to the first axial supporting ring end face (31) is H3, wherein H1, H2 and H3 satisfy the following relations: h3 > H1; 0.25 < H2/H1 < 1, the second ball bearing (42) has a height H4, the second radial support torus (34) has a height H5, the second annular groove (62) has a top to second axial support torus end face (33) height H6, wherein H4, H5 and H6 satisfy the following relationships: h6 > H4; 0.25 < H5/H4 < 1.

5. The middle pipe with an annular groove structure as claimed in claim 1, wherein the groove cross-sectional profiles of the first annular groove (61) and the second annular groove (62) are square, rectangular, semicircular, semi-elliptical or triangular.

6. The middle pipe with the annular groove structure as claimed in claim 1, wherein the grooves of the first annular groove (61) and the second annular groove (62) are formed in a whole circle along the circumferential direction of the middle pipe (3), or a plurality of grooves are formed along the circumferential direction of the middle pipe (3), or a plurality of circles along the axial direction of the middle pipe (3), and the grooves are communicated with each other.

7. The middle pipe with an annular groove structure as claimed in claim 1, wherein the upper ends of the first annular groove (61) and the second annular groove (62) are provided with groove chamfers (63) for facilitating the injection of the adhesive.

8. A middle tube with an annular groove structure according to claim 1, wherein the upper groove ends of the first annular groove (61) and the second annular groove (62) extend to the end face of the middle tube (3).

9. A process for assembling a middle tube with an annular groove structure for a ball bearing according to any one of claims 1 to 8, comprising the steps of:

step S1: placing the bottom surface of the outer frame (2) downwards, and installing a first ball bearing (41) into the inner part of one end of the middle pipe (3);

step S2: the liquid injection nozzle extends into the outer leakage part of the first annular groove (61), the adhesive is injected into the first annular groove (61), the adhesive is kept stand for a period of time to fully flow into the space between the first ball bearing (41) and the middle pipe (3), and the adhesive is preliminarily solidified between the first ball bearing (41) and the middle pipe (3) so as to preliminarily fix the first ball bearing (41);

step S3: placing the bottom surface of the outer frame (2) upwards, and installing a second ball bearing (42) into the inner part of the other end of the middle pipe (3);

step S4: the liquid injection nozzle extends into the outer leakage part of the second annular groove (62), the adhesive is injected into the second annular groove (62), the adhesive is kept stand for a period of time to fully flow into the space between the second ball bearing (42) and the middle pipe (3), and the adhesive is preliminarily solidified between the second ball bearing (42) and the middle pipe (3) so as to preliminarily fix the second ball bearing (42);

step S5: and standing for a period of time to solidify the adhesive among the first ball bearing (41), the second ball bearing (42) and the middle pipe (3), wherein the first ball bearing (41) and the second ball bearing (42) are assembled.

10. The process for installing the middle tube with the annular groove structure into the ball bearing according to claim 9, wherein in the step S1, a first open communication chamber for containing the adhesive is formed among the first annular groove (61), the first ball bearing (41) and the middle tube (3);

a second open communication chamber for containing the adhesive is formed among the second annular groove (62), the second ball bearing (42) and the middle pipe (3) in the step S3;

in the step S4, the outer frame (2) is turned over again, the spring and the rotor assembly are installed at the upper end of the middle tube (3), the retaining ring is installed at the lower end of the middle tube, the first ball bearing (41) and the second ball bearing (42) are corrected and positioned in concentricity by using the shaft core of the rotor assembly, the first ball bearing (41) is axially positioned by using the spring, and the second ball bearing (42) is axially positioned by using the retaining ring.

Technical Field

The invention relates to the technical field of fan middle tube structure improvement, in particular to a middle tube with an annular groove structure and a process for installing a ball bearing.

Background

At present, the size of an electronic equipment system is gradually reduced, the heat dissipation fan needs to provide the highest heat dissipation performance in a limited installation space to meet the market demand, so that the industry has more and more demands on high-speed fans, and in order to reduce the overall vibration and ensure the service life of the high-speed fans, the high-speed fans generally adopt an assembly process of fixing a ball bearing outer ring and a middle pipe.

At present, two fixing methods are generally adopted for fixing a middle pipe and a ball bearing outer ring of a high-speed fan: firstly, adopting adhesive to bond and fix; secondly, the fixing is carried out in an interference fit mode. The process of bonding and fixing by using the adhesive comprises the steps of firstly coating a layer of adhesive on the inner surface of the middle pipe, then installing the ball bearing in the middle pipe, and fixing the ball bearing in the middle pipe by using the adhesive. The assembly process adopting the interference fit has the advantages that firstly, the interference fit needs more production equipment, the assembly is more complex, the production cost is higher, then the concentricity of the upper ball bearing and the lower ball bearing after the assembly is greatly influenced by the middle pipe, and the concentricity is difficult to guarantee.

The assembly process of the two structures cannot meet the fixing requirement of the market on the ball bearing in the high-speed fan.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides the middle tube with the annular groove structure and the process for installing the ball bearings, improves the concentricity of the two assembled ball bearings, avoids the possibility that an adhesive passes through the dust cap of the ball bearing and enters the ball bearing, reduces the failure caused by insufficient concentricity and the adhesive entering the ball bearing, improves the product yield, prolongs the service life of the fan, and simplifies the fixing process of the ball bearings and the middle tube.

In order to achieve the purpose, the invention provides a middle pipe with an annular groove structure, which comprises a middle pipe, wherein the middle pipe is arranged in a static impeller hub, one end of the middle pipe is fixedly provided with a first ball bearing through bonding of an adhesive, the other end of the middle pipe is fixedly provided with a second ball bearing through bonding of an adhesive, one end of the middle pipe is provided with a first radial supporting circular ring surface, the other end of the middle pipe is provided with a second radial supporting circular ring surface, the first radial supporting circular ring surface is provided with a first annular groove, the height of the first annular groove is higher than that of the first ball bearing, the second radial supporting circular ring surface is provided with a second annular groove, and the height of the second annular groove is higher than that of the second ball bearing.

Preferably, the stator hub is mounted inside the outer frame.

Preferably, the first annular groove, the first ball bearing and the middle pipe form a first open communication chamber for containing the adhesive therebetween; a second open communication chamber for receiving the adhesive is formed between the second annular groove, the second ball bearing and the middle tube.

Preferably, one end of the middle pipe is further provided with a first axial supporting circular ring end face, the other end of the middle pipe is further provided with a second axial supporting circular ring end face, the height of the first ball bearing is H1, the height of the first radial supporting circular ring face is H2, the height from the top of the first annular groove to the first axial supporting circular ring end face is H3, and H1, H2 and H3 satisfy the following relations: h3 > H1; 0.25 < H2/H1 < 1, the second ball bearing has a height H4, the second radial support torus has a height H5, the second annular groove top to second axial support torus end surface has a height H6, wherein H4, H5 and H6 satisfy the following relationships: h6 > H4; 0.25 < H5/H4 < 1.

Preferably, the cross-sectional profile of the first annular groove and the second annular groove is square, rectangular, semicircular, semi-elliptical or triangular.

Preferably, the grooves of the first annular groove and the second annular groove are formed in a whole circle along the circumferential direction of the middle pipe or are provided with a plurality of grooves along the circumferential direction of the middle pipe or are formed in a plurality of circles along the axial direction of the middle pipe, and the grooves are communicated with each other.

Preferably, the upper ends of the first annular groove and the second annular groove are provided with groove chamfers for facilitating the injection of the adhesive.

Preferably, the upper ends of the first annular groove and the second annular groove extend to the end face of the middle pipe.

The invention also provides a process for assembling the middle pipe with the annular groove structure into the ball bearing, which comprises the following steps:

step S1: placing the bottom surface of the outer frame downwards, and installing a first ball bearing into the inner part of one end of the middle pipe;

step S2: the liquid injection nozzle extends into the outer leakage part of the first annular groove, the adhesive is injected into the first annular groove, the first annular groove is kept stand for a period of time, so that the adhesive fully flows into the space between the first ball bearing and the middle pipe, and meanwhile, the adhesive is preliminarily solidified between the first ball bearing and the middle pipe, so that the first ball bearing is preliminarily fixed;

step S3: placing the bottom surface of the outer frame upwards, and installing a second ball bearing into the inner part of the other end of the middle pipe;

step S4: the liquid injection nozzle extends into the outer leakage part of the second annular groove, the adhesive is injected into the second annular groove, the second annular groove is kept stand for a period of time, so that the adhesive fully flows into a space between the second ball bearing and the middle pipe, and meanwhile, the adhesive is preliminarily solidified between the second ball bearing and the middle pipe, so that the second ball bearing is preliminarily fixed;

step S5: and standing for a period of time to enable the adhesive to be solidified among the first ball bearing, the second ball bearing and the middle pipe, wherein the first ball bearing and the second ball bearing are assembled completely.

Preferably, in the step S1, a first open communication chamber for receiving the adhesive is formed among the first annular groove, the first ball bearing and the middle pipe;

a second open communication chamber for accommodating the adhesive is formed among the second annular groove, the second ball bearing and the middle pipe in the step S3;

in step S4, the outer frame is turned over again, the spring and the rotor assembly are installed at the upper end of the middle tube, the retaining ring is installed at the lower end of the middle tube, the first ball bearing and the second ball bearing are corrected and positioned in concentricity by using the shaft core of the rotor assembly, the first ball bearing is axially positioned by using the spring, and the second ball bearing is axially positioned by using the retaining ring.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention is characterized in that one end of the middle pipe is provided with a first annular groove, the other end of the middle pipe is provided with a second annular groove, the first annular groove and the first ball bearing form a chamber, the second annular groove and the second ball bearing form another chamber, the two chambers are internally provided with adhesives for bonding the first ball bearing and the second ball bearing, when the first ball bearing and the second ball bearing are arranged in the middle pipe, the two chambers are higher than the first ball bearing and the second ball bearing and higher than the first ball bearing and the second ball bearing, the parts of the chambers are used for injecting the adhesives, the upper ends of the first annular groove and the second annular groove are provided with groove chamfers for facilitating the injection of the adhesives, the assembly structure is favorable for improving the concentricity of the first ball bearing and the second ball bearing after assembly, and the possibility that the adhesives pass through a dust cap of the ball bearing and enter the ball, the failure caused by insufficient concentricity and the fact that the binder enters the ball bearing is reduced, the product assembly yield is improved, the service life of the fan is prolonged, and the fixing process of the ball bearing and the middle pipe is simplified.

2. The first radial support ring surface is a first ball bearing radial support, the height H2 of the first radial support ring surface is greater than 1/4 of the height H1 of the first ball bearing (namely H2/H1 is greater than 0.25), so that the support area is prevented from being too small, the first ball bearing is favorably and firmly fixed with the middle pipe, and the service life of the fan is prolonged; the second radial support ring surface is the radial support of second ball bearing, the height H5 of the second radial support ring surface is greater than 1/4 of second ball bearing height H4 (H5/H4 > 0.25) to avoid supporting the area undersize, be favorable to second ball bearing and well pipe fixed firm, be favorable to prolonging the life-span of fan, simultaneously the height H5 of the second radial support ring surface is less than second ball bearing height H4 (H5/H4 < 1) to avoid unable more binder of holding, lead to the bonding area undersize, be favorable to second ball bearing and well pipe fixed firm, be favorable to prolonging the life-span of fan.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic cross-sectional view of a middle tube with an annular groove structure according to the present invention;

FIG. 2 is an enlarged schematic view of I in FIG. 1;

FIG. 3 is an enlarged schematic view of II of FIG. 1;

FIG. 4 is a schematic view of the first annular groove of FIG. 2 with the upper end extending to the end face of the middle tube;

fig. 5 is a schematic view showing the structure in which the upper end of the second annular groove in fig. 3 extends to the end surface of the middle pipe.

The figure includes:

1-static impeller hub, 2-outer frame, 3-middle tube, 41-first ball bearing, 42-second ball bearing, 31-first axial supporting ring end face, 32-first radial supporting ring face, 61-first annular groove, 33-second axial supporting ring end face, 34-second radial supporting ring face, 62-second annular groove and 63-groove chamfer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are one embodiment of the present invention, and not all embodiments of the present invention. All other embodiments obtained by a person skilled in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.

Example one

Referring to fig. 1 to 5, the present invention provides a middle tube with an annular groove structure, including a middle tube 3, where the middle tube 3 is installed inside a static impeller hub 1, the static impeller hub 1 is installed inside an outer frame 2, one end of the middle tube 3 is fixedly provided with a first ball bearing 41 through an adhesive, and the other end of the middle tube 3 is fixedly provided with a second ball bearing 42 through an adhesive, and both the first ball bearing 41 and the second ball bearing 42 are fixedly installed on the middle tube 3 through an adhesive.

As shown in fig. 2, one end of the middle pipe 3 is provided with a first axial supporting ring end surface 31 and a first radial supporting ring surface 32, the first axial supporting ring end surface 31 is axially supported by the first ball bearing 41, the first radial supporting ring surface 32 is radially supported by the first ball bearing 41, the first radial supporting ring surface 32 is provided with a first annular groove 61, and the height of the first annular groove 61 is higher than that of the first ball bearing 41.

First annular groove 61 highly must be higher than first ball bearing 41's height, otherwise will unable to pour into the binder into first annular groove 61 inside, more unable make the binder flow into between first ball bearing 41 and the well pipe 3, above-mentioned package assembly need not to press and joins in marriage, be favorable to improving first ball bearing 41 and well pipe 3's concentricity, the while has avoided the binder to pass the shield of first ball bearing 41 and has got into the inside possibility of first ball bearing 41, the inefficacy that causes because of the concentricity is not enough and the binder gets into first ball bearing 41 has been reduced, the product assembly yields has been promoted, the fan life has been improved, the fixing process of first ball bearing 41 and well pipe 3 has been simplified.

Mounting manner of the first ball bearing 41: first, the first ball bearing 41 is fitted into the interior of one end of the middle tube 3; secondly, the adhesive is injected into the first annular groove 61; again, the adhesive automatically flows into between the first ball bearing 41 and the center tube 3; finally, the adhesive is left for a period of time to solidify between the first ball bearing 41 and the center tube 3, and the first ball bearing 41 is assembled.

As shown in fig. 3, the other end of the middle tube 3 is provided with a second axial supporting ring end surface 33 and a second radial supporting ring surface 34, the second axial supporting ring end surface 33 is axially supported by the second ball bearing 42, the second radial supporting ring surface 34 is radially supported by the second ball bearing 42, the second radial supporting ring surface 34 is provided with a second annular groove 62, and the height of the second annular groove 62 is higher than the height of the second ball bearing 42.

The height of second annular groove 62 is higher than the height of second ball bearing 42, otherwise can't pour into the binder into second annular groove 62 inside, more can't make the binder flow into between second ball bearing 42 and the well pipe 3, above-mentioned package assembly need not to press and joins in marriage, be favorable to improving the concentricity of second ball bearing 42 and well pipe 3, avoided the binder to pass the shield of second ball bearing 42 and got into the inside possibility of second ball bearing 42 simultaneously, the inefficacy that causes because of the concentricity is not enough and the binder gets into second ball bearing 42 has been reduced, the product assembly yields has been promoted, the fan life has been improved, the fixing process of second ball bearing 42 and well pipe 3 has been simplified.

Mounting manner of the second ball bearing 42: first, the second ball bearing 42 is fitted into the inside of the other end of the middle tube 3; next, the adhesive is injected into the interior of the second annular groove 62; again, the adhesive automatically flows into between the second ball bearing 42 and the center tube 3; finally, the adhesive is left for a period of time to solidify between the second ball bearing 42 and the center tube 3, and the second ball bearing 42 is assembled.

A first open communication chamber for containing the adhesive is formed among the first annular groove 61, the first ball bearing 41 and the middle tube 3; second open intercommunication cavity that is used for holding the binder has been formed between second annular groove 62, second ball bearing 42 and the well pipe 3, first open intercommunication cavity and second open intercommunication cavity all are the intercommunication formula cavity, and the technology of binder evenly distributed in the cavity realizes comparatively simply, is favorable to reducing manufacturing cost and the degree of difficulty that reduces assembly process, can reduce manufacturing cost, is favorable to improving the bonding effect of first ball bearing 41 and second ball bearing 42 and well pipe 3 simultaneously.

As shown in fig. 2, the height of the first ball bearing 41 is H1, the height of the first radial support ring surface 32 is H2, and the height from the top of the first annular groove 61 to the first axial support ring end surface 31 is H3, wherein H1, H2 and H3 satisfy the following relationships: h3 > H1; 0.25 < H2/H1 < 1, the first radial supporting ring surface 32 is used for radial supporting of the first ball bearing 41, so the height H2 of the first radial supporting ring surface 32 is greater than 1/4 of the height H1 of the first ball bearing 41 (namely H2/H1 > 0.25), which is beneficial to avoiding the supporting area from being too small, and is beneficial to firmly fixing the first ball bearing 41 and the middle pipe 3, and prolonging the service life of the fan, meanwhile, the height H2 of the first radial supporting ring surface 32 is less than the height H1 of the first ball bearing 42 (namely H2/H1 < 1), so as to avoid the situation that more adhesive cannot be contained, which results in the adhesive area being too small, and is beneficial to firmly fixing the first ball bearing 41 and the middle pipe 3, and prolonging the service life of the fan.

As shown in fig. 3, the height of the second ball bearing 42 is H4, the height of the second radial support torus 34 is H5, and the height from the top of the second annular groove 62 to the second axial support torus end face 33 is H6, wherein H4, H5 and H6 satisfy the following relationships: h6 > H4; H5/H4 is more than 0.25 and less than 1, the second radial supporting ring surface 34 is used for radially supporting the second ball bearing 42, the height H5 of the second radial supporting ring surface 34 is more than 1/4 of the height H4 of the second ball bearing 42 (namely H5/H4 is more than 0.25), so that the supporting area is prevented from being too small, the second ball bearing 42 and the middle pipe 3 are fixed firmly, the service life of the fan is prolonged, meanwhile, the height H5 of the second radial supporting ring surface 34 is less than the height H4 of the second ball bearing 42 (namely H5/H4 is less than 1), so that the situation that more adhesives cannot be contained is avoided, the bonding area is too small, the second ball bearing 42 and the middle pipe 3 are fixed firmly, and the service life of the fan is prolonged.

The groove cross-sectional profile of the first and second annular grooves 61, 62 may be polygonal, for example: the shape of the triangle, the square, the rectangle, etc., may also be a semicircle or a semi-ellipse, which may be selected according to the actual situation, and is not limited in this embodiment.

The recess of first annular groove 61 and second annular groove 62 is for being equipped with a plurality of recesses or having a plurality of rings of recesses along well 3 axial of well 3 or along 3 circumferencial directions of well pipe for along 3 circumferencial directions of well pipe, communicate each other between the recess, be favorable to the binder to circulate between the recess, be favorable to the binder fully circulate and smoothly coat between first annular groove 61 and second annular groove 62 and well pipe 3.

The upper ends of the first annular groove 61 and the second annular groove 62 are provided with groove chamfers 63 for facilitating the injection of the adhesive.

As shown in fig. 4 and 5, the upper ends of the first annular groove 61 and the second annular groove 62 extend to the end surface of the middle pipe 3, and the structure can facilitate processing and reduce manufacturing cost.

Example two

The second embodiment of the invention provides a process for assembling the middle pipe with the annular groove structure into the ball bearing, which comprises the following steps:

step S1: the bottom surface of the outer frame 2 is placed downwards, the first ball bearing 41 is arranged inside one end of the middle pipe 3, and specifically, a first open communication chamber for containing the adhesive is formed among the first annular groove 61, the first ball bearing 41 and the middle pipe 3.

Step S2: will annotate the liquid mouth and stretch into the outer hourglass part to first annular groove 61, pour into the binder into first annular groove 61 inside, it makes the binder fully flow into to between first ball bearing 41 and the well pipe 3 to stew a period of time, and the binder is tentatively solidified between first ball bearing 41 and well pipe 3 simultaneously to carry out preliminary fixed to first ball bearing 41.

Step S3: the bottom surface of the outer frame 2 is placed upwards, the second ball bearing 42 is arranged in the inner part of the other end of the middle pipe 3, and specifically, a second open type communication chamber for containing the adhesive is formed among the second annular groove 62, the second ball bearing 42 and the middle pipe 3.

Step S4: will annotate the liquid mouth and stretch into the outer hourglass part to second annular groove 62, pour into the binder into inside second annular groove 62, a period of time of stewing makes the binder fully flow into between second ball bearing 42 and well pipe 3, the binder is simultaneously tentatively solidified between second ball bearing 42 and well pipe 3, so as to tentatively fix second ball bearing 42, it is further again, overturn frame 2 once more, pack into spring and rotor group in well pipe 3 upper end, the buckle is packed into to the lower extreme, the axle core that utilizes the rotor group to establish carries out concentricity correction and location to first ball bearing 41 and second ball bearing 42, utilize the spring to carry out axial positioning to first ball bearing 41, utilize the buckle to carry out axial positioning to second ball bearing 42.

Step S5: and standing for a period of time to solidify the adhesive between the first ball bearing 41, the second ball bearing 42 and the middle pipe 3, wherein the first ball bearing 41 and the second ball bearing 42 are assembled.

The assembling method is simple to operate, the assembly and fixation yield of the first ball bearing 41, the second ball bearing 42 and the middle pipe 3 is improved, the concentricity of the first ball bearing 41, the second ball bearing 42 and the middle pipe 3 is ensured, and meanwhile the service life of the fan is prolonged.

In conclusion, the beneficial effects of the invention are as follows:

according to the invention, the middle tube 3 is provided with the first annular groove 61 at one end and the second annular groove 62 at the other end, the first annular groove 61 and the first ball bearing 41 form a chamber, the second annular groove 62 and the second ball bearing 42 form another chamber, the two chambers are internally provided with the adhesive for bonding the first ball bearing 41 and the second ball bearing 42, when the first ball bearing 41 and the second ball bearing 42 are arranged in the middle tube 3, the two chambers are higher than the first ball bearing 41 and the second ball bearing 42 and higher than the first ball bearing 41 and the second ball bearing 42 for injecting the adhesive, the upper ends of the first annular groove 61 and the second annular groove 62 are provided with the groove chamfer 63 for facilitating the injection of the adhesive, the assembly structure is favorable for improving the concentricity of the first ball bearing 41 and the second ball bearing 42 after assembly, and the possibility that the adhesive enters the ball bearing through the dustproof cover of the ball bearing is avoided, the failure caused by insufficient concentricity and the adhesive entering the ball bearing is reduced, the product assembly yield is improved, the service life of the fan is prolonged, and the fixing process of the ball bearing and the middle pipe 3 is simplified; the first radial support circular ring surface 32 is used for radially supporting the first ball bearing 41, the height H2 of the first radial support circular ring surface 32 is greater than 1/4 of the height H1 of the first ball bearing 41 (namely H2/H1 is greater than 0.25), so that the support area is prevented from being too small, the first ball bearing 41 and the middle pipe 3 are favorably and firmly fixed, and the service life of the fan is prolonged; the second radial support ring surface 34 is radially supported by the second ball bearing 42, the height H5 of the second radial support ring surface 34 is greater than 1/4 of the height H4 of the second ball bearing 42 (i.e., H5/H4 is greater than 0.25), so as to avoid the undersize of the support area, so as to facilitate the fixation of the second ball bearing 42 and the middle pipe 3, so as to prolong the service life of the fan, and meanwhile, the height H5 of the second radial support ring surface 34 is less than the height H4 of the second ball bearing 42 (i.e., H5/H4 < 1), so as to avoid the incapability of accommodating more adhesives, so as to cause the undersize of the bonding area, so as to facilitate the fixation of the second ball bearing 42 and the middle pipe 3, so as to facilitate the.