CN113628947A

CN113628947A - Liquid metal bearing and assembling method thereof

Info

Publication number: CN113628947A
Application number: CN202110855146.4A
Authority: CN
Inventors: 胡强; 王瑞海; 龚海华; 吕向英
Original assignee: Cetc Ruishi Technology Beijing Co ltd
Current assignee: Cetc Ruishi Technology Beijing Co ltd
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2021-11-09

Abstract

The invention provides a liquid metal bearing and an assembling method thereof, wherein the liquid metal bearing comprises a first structural member; the second structural part is fixedly combined with the first structural part; and a seal ring made of a ductile metallic material; at least one sealing groove for accommodating a sealing ring is formed between the first structural member and the second structural member; the cross-sectional shape of the seal groove comprises two inclined edges which gradually gather towards the rotating shaft. The liquid metal bearing has the advantages of good sealing effect, small processing difficulty and high stability.

Description

Liquid metal bearing and assembling method thereof

Technical Field

The invention relates to the technical field of X-ray tubes. And more particularly, to a liquid metal bearing and a method of assembling the same.

Background

In the existing liquid metal bearing, for the convenience of process and use, the structural parts are mostly connected by screws, so that the liquid metal sealed in the bearing gap has the possibility of leakage. Because the liquid metal has higher surface tension, the surface roughness of the liquid metal is better than Ra0.2 through the matching surface of the structural part, and the flatness is below 2 mu m to realize better sealing. However, during the operation of the X-ray tube, the anode rotates at a high speed, the rotation speed of the liquid bearing supporting the anode reaches 10000 rpm, and the high pressure caused by the high rotation speed may still cause the leakage of the liquid metal bearing. Meanwhile, the bearing is subjected to high temperature in the working process, and the high temperature is not beneficial to sealing of liquid metal.

The further treatment is to coat an aluminum oxide or titanium oxide film on the surface of the structural part, and the anti-wetting property of the film layer to the liquid metal is utilized to improve the sealing property of the liquid metal bearing. And because the alumina film and the titanium oxide film are stable at high temperature, the sealing capability of the bearing at high temperature can be improved. However, the aluminum oxide film and the titanium oxide film are relatively hard, and the defects of the matching surfaces cannot be filled by the film coating method or the film thickness unevenness, and the film coating mode, so that a large leakage risk still exists when the bearing rotates at a high speed or further rotates at a high speed.

Disclosure of Invention

In view of the above problems, the present invention provides a liquid metal bearing, which has a good sealing effect, a small processing difficulty, and a high stability.

The invention also provides a liquid metal bearing assembly method.

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

in one aspect, the present invention provides a liquid metal bearing comprising:

a first structural member;

the second structural part is fixedly combined with the first structural part; and

a seal ring made of a ductile metallic material;

at least one sealing groove for accommodating a sealing ring is formed between the first structural member and the second structural member;

the cross-sectional shape of the seal groove comprises two inclined edges which gradually gather towards the rotating shaft.

Further, it is preferable that the sealing groove includes a first groove portion provided in the first member and a second groove portion provided in the second member.

Further, it is preferable that the first groove portion and the second groove portion have a sectional shape which is symmetrical with respect to the contact surface.

In addition, it is preferable that the cross-sectional shape of the sealing groove is a triangle or a trapezoid.

In addition, it is preferable that the cross-sectional shape of the seal groove includes a head portion and a wedge-shaped tail portion communicating with the head portion.

Furthermore, it is preferable that the head portion has a rectangular shape, and the depth of the rectangular shape is the same as the depth of the wedge-shaped tail portion.

In addition, preferably, the included angle formed by the two oblique edges of the sealing groove is 60-80 degrees.

In addition, preferably, the inner diameter of the sealing groove is 0.5 mm-2 mm away from the edge of the rotating shaft.

The invention provides a liquid metal bearing assembly method, which comprises a first structural member and a second structural member fixedly combined with the first structural member;

at least one sealing groove for accommodating a sealing ring is arranged between the first structural member and the second structural member, and the cross section of the sealing groove comprises two inclined edges gradually gathered towards the rotating shaft;

the width of the metal ring is less than or equal to that of the sealing groove, the volume of the metal ring is 5 to 30 percent larger than that of the sealing groove,

the first member and the second member are in frictional contact and tightly fixed by fastening, and the metal ring forms a sealing ring in the sealing groove.

In addition, it is preferable that the inner side of the seal ring is in close contact with the seal groove, and the outer side of the seal ring has a gap from the seal groove.

The invention has the beneficial effects that:

according to the invention, the sealing groove is matched with the sealing ring made of an extensible metal material, the metal ring is arranged in the sealing groove, so that the metal ring can be deformed into the sealing ring to a certain extent when the first structural member and the second structural member are fastened, and the sealing effect of the bearing is enhanced. In addition, after the sealing groove is filled with the sealing ring, the sealing area can be increased, the risk of liquid metal leakage is reduced, the sealing effect of the bearing is effectively improved, the surface quality requirement of the liquid metal bearing is reduced, the processing difficulty of the liquid metal bearing is reduced, the stability is improved, and the service life is prolonged.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Figure 1 is a cross-sectional view of a sealing groove having a triangular cross-section according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of a sealing groove of another embodiment of the present invention, the cross-section of which is triangular.

Fig. 3 is a cross-sectional view of a sealing groove having a trapezoidal cross-section according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view of a sealing groove of another embodiment of the present invention, the cross-section of which is trapezoidal.

Figure 5 is an enlarged view at the seal groove of one embodiment of the present invention.

Fig. 6 is a cross-sectional view of one embodiment of the present invention.

Fig. 7 is an enlarged view at the seal groove of another embodiment of the present invention.

Fig. 8 is an enlarged view of the junction of the extension and the wedge-shaped tail of one embodiment of the present invention.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be considered a part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In order to effectively improve the sealing effect of the liquid metal bearing, reduce the surface quality requirement of the liquid metal bearing, reduce the processing difficulty of the liquid metal bearing, increase the stability and prolong the service life of the liquid metal bearing. The invention provides a liquid metal bearing, which is shown in a combined manner in fig. 1 to 8, and specifically comprises: a first structural member 01; a second structural member 02 combined and fixed with the first structural member 01; and a sealing ring 04 made of a ductile metal material; at least one sealing groove for accommodating a sealing ring 04 is formed between the first structural member 01 and the second structural member 02; the cross-sectional shape of the seal groove includes two hypotenuses that gradually converge toward the shaft 03.

Referring to fig. 5, when the first structural member 01 and the second structural member 02 are not assembled and fixed, the metal ring 05 is not deformed between the two structural members, and the cross section of the metal ring 05 is rectangular.

The invention arranges the metal ring 05 in the sealing groove by matching the sealing groove with the sealing ring 04 made of ductile metal material, so that the metal ring 05 can generate certain deformation to become the sealing ring 04 when the first structural member 01 and the second structural member 02 are fastened, thereby enhancing the sealing effect of the bearing, and the section of the sealing ring is designed to comprise two sealing grooves with bevel edges which gradually converge towards the rotating shaft 03, so that the contact area between the sealing ring 04 and the liquid metal is greatly reduced, in the invention, after the metal ring 05 is positioned in the sealing groove and is pressed, the prestress applied to the first structural component 01 and the second structural component 02 is obviously weakened compared with the sealing groove with other cross sections, so that a gap can be prevented from being generated between the first structural component 01 and the second structural component 02 due to the excessive prestress applied to the first structural component 01 and the second structural component 02, thereby causing liquid metal leakage that affects the normal use of the liquid metal bearing. In addition, after the sealing groove is filled with the sealing ring 04, the sealing area can be increased, the risk of liquid metal leakage is reduced, the sealing effect of the bearing is effectively improved, the surface quality requirement of the liquid metal bearing is reduced, the processing difficulty of the liquid metal bearing is reduced, the stability is improved, and the service life is prolonged.

It can be understood that the liquid metal bearing belongs to a sliding bearing, and has the advantages of low noise, long service life and the like when being applied to the X-ray tube, so that the liquid metal bearing becomes an essential part of a high-end product of the X-ray tube. Liquid metal bearings generally comprise a housing; and a rotating shaft 03 rotatable with respect to the housing; the housing comprises a first structural member 01; and a second structural member 02 combined and fixed with the first structural member 01; the sealing ring 04 is located between the first structural part 01 and the second structural part 02.

The cross-sectional shape of the sealing groove includes two oblique sides that gradually converge toward the rotating shaft 03, and specifically, the cross-sectional shape of the sealing groove is triangular or trapezoidal.

As mentioned in the background of the invention, the sealing of liquid metal bearings has always been an important consideration for liquid metal bearings, and bearing failure due to liquid metal leakage is a high contributor to bearing failure. On one hand, the liquid metal leakage can reduce the internal lubrication of the bearing, increase the friction coefficient of the bearing, increase the abrasion of the bearing and finally cause the failure of the bearing; on the other hand, leakage of liquid metal into the high-pressure region of the X-ray tube will affect the withstand voltage of the X-ray tube.

It will be appreciated that liquid metal bearings are plain bearings in which the liquid metal acts as a bearing lubrication, the liquid metal being present in the bearing gap. Liquid metal is highly corrosive and corrodes most metal materials, and in order to reduce corrosion of the liquid metal to the structural component, the structural component is generally made of molybdenum, tungsten or alloy materials thereof, which are resistant to corrosion of the liquid metal.

The sealing groove is matched with the sealing ring 04 to achieve a good sealing effect, the sealing groove can be independently used as a bearing sealing structure, and can be simultaneously used with other sealing forms to form a composite sealing form with a better sealing effect.

It will be appreciated that the thickness of the metal ring 05 should be slightly greater than the depth of the sealing groove, and will deform during the tightening process to fill in machining defects in the surface of the structural member. The volume of the metal ring 05 is 20-30% larger than that of the sealing groove with the triangular or trapezoidal section. Therefore, after extrusion, the sealing ring 04 can be filled inside the sealing groove, and appropriate prestress is generated to achieve a good sealing effect.

In a specific embodiment, with respect to the provision of the sealing groove, the sealing groove includes a first groove portion provided in the first structural member 01 and a second groove portion provided in the second structural member. Further, the first groove portion and the second groove portion are provided symmetrically with respect to the contact surface in cross-sectional shape. As shown in fig. 1, liquid metal exists in the bearing gap, and the positions a, b and c are filled with the liquid metal. Specifically, when the first groove portion and the second groove portion are disposed on the upper side and the lower side of the contact surface, that is, when the first groove portion on the first structural member 01 and the second groove portion on the second structural member 02 together form a seal groove, the first groove portion and the second groove portion are disposed opposite to each other and cooperate with the metal ring 05 together to seal the bearing.

In the above embodiment, a plurality of sealing grooves may be provided, and a plurality of metal rings 05 may be correspondingly disposed between the two structural members and engaged with the sealing grooves.

Referring to the illustrated structure, the structure shown in fig. 1 is provided with groove portions on both the first structural member 01 and the second structural member 02 which are matched with each other, and similarly, a sealing groove can be provided on only one side of the component as shown in fig. 2 to achieve similar effects.

In one embodiment, the sealing ring 04 is made of a ductile material; such as: gold, copper, platinum, nickel, etc., which, in addition to being ductile, also need to have certain high temperature resistance, be able to withstand the operating temperatures of the bearing not exceeding 600 ℃, and be able to withstand repeated temperature increases.

In addition, the ductile material is further beneficial to sealing of the bearing after being treated by adopting an annealing treatment method. If the copper is not annealed, the maximum elongation is 15-25%, and the elongation after annealing can reach 30-50%; the maximum elongation of the nickel after annealing treatment is 10-30%. The copper can be annealed at 450-600 ℃, and the annealing temperature of the nickel is about 660 ℃. The material should be high-purity metal material with purity above 99.99%, specifically, the copper should be high-purity oxygen-free copper with low oxygen content, because the copper pad with high oxygen content is easy to crack in the high-temperature treatment process.

In an alternative embodiment, a metal ring with a triangular or trapezoidal cross section can be used, which can effectively save the amount of the sealing ring required to be manufactured and the manufacturing cost. The sealing function can be achieved, and processing defects of the sealing ring can be reduced, so that the sealing effect is enhanced.

In order to enable the metal ring 05 to be tightly filled into the sealing groove and prevent a gap from being left on one side close to the rotating shaft 03 to influence the sealing effect, an included angle formed by two inclined edges of the sealing groove is 60-80 degrees.

In a particular embodiment, the cross-sectional shape of the seal slot includes a head and a wedge-shaped tail in communication with the head. The inward extending part extends from the end part of the wedge-shaped tail part close to the rotating shaft 03 to the direction close to the rotating shaft 03. In this embodiment, the head is rectangular, the depth of the rectangle being the same as the depth of the wedge-shaped tail. Specifically, as shown in fig. 6 and 7. Liquid metal exists in the bearing gap, and the positions a, b and c are filled with the liquid metal. When fasteners such as screws are adopted to fasten the two structural members so as to enable the ductile metal ring 05 to deform to a certain extent, the head of the whole sealing groove is filled with the ductile metal ring, and a certain pretightening force is generated, so that the bearing can be compressed and sealed. In the fastened state, the sealing ring 04 fills the head, preventing the formation of air chambers due to voids. If the air chamber is formed, the air in the air chamber is slowly released, the vacuum degree in the vacuum cavity of the X-ray tube is influenced for a long time, and the product testing time is prolonged or the product testing fails.

In this embodiment, the volume of the metal ring 05 is 5% to 10% larger than the volume of the seal groove. The thickness of the metal ring 05 is slightly higher than the depth of the inward extending part of the two structural members after being fastened, and the metal ring 05 deforms in the fastening process so as to make up for the processing defects on the surfaces of the two structural members. The coverage area of the sealing surface is increased, and the risk of liquid metal leakage is reduced. When the volume of the metal ring 05 is 5% -10% larger than that of the sealing groove, and the metal ring 05 is compressed and filled in the inward extending part and the wedge-shaped tail part of the sealing groove, the prestress of the first structural member 01 and the second structural member 02 is within a reasonable bearing range, so that the first structural member 01 and the second structural member 02 can be effectively prevented from generating a gap with each other due to the fact that the first structural member 01 and the second structural member 02 are subjected to overlarge prestress, liquid metal leakage is caused, and normal use of the liquid metal bearing is influenced.

Fig. 7 shows the assembly condition before the two structural members are fastened, and at this time, the metal ring 05 is not deformed yet, and the cross section of the metal ring 05 is rectangular, and by designing the depth of the sealing groove and the inner diameter of the metal ring 05 into reasonable dimensions, the sealing ring 04 can be filled in the cavity of the inner extension part on the inner side of the whole wedge-shaped tail part after extrusion deformation, so that the sealing effect is achieved. Specifically, for example, under the action of the fastening force, the amount of change of the metal ring 05 reaches 5% to 10%, and effective sealing can be achieved. Further, the metal ring 05 has a reasonable inner diameter allowance, so that the sealing ring 04 formed after being extruded can fill the whole sealing groove. It will be appreciated that the depth of the slots in the two structural members will take into account the amount of deformation of the metal ring 05, and that due to the spacing means, the actual amount of deformation of the metal ring 05 will be less than its maximum achievable. The design value of the deformation of the metal ring 05 is within the range of 5-10%, so that good sealing can be realized, and the maximum deformation of materials such as gold, silver, copper, platinum, nickel and the like can not be exceeded.

In addition, an included angle formed by the connecting part of the wedge-shaped tail part and the inward extending part

A specific embodiment is shown in fig. 8. The depth of the sealing grooves on the first structural member 01 and the second structural member 02 is 1-1.5 mm, and the width is 4-6 mm. A metal ring 05 made of gold, copper, platinum, nickel, stainless steel, etc. is disposed in the sealing groove. Under the action of fastening force, the corner formed at the joint of the wedge-shaped tail part and the head part of the sealing groove extrudes the metal ring 05 to generate large deformation, the head part is filled with the sealing ring 04 formed after the deformation, the processing defect of the surface of a structural part can be filled, the first structural part 01 and the second structural part 02 are in close contact with the sealing ring 04 and keep certain pretightening force, and effective sealing can be realized.

It can be understood that, because the corner stroke is relatively large, the elongation of the metal ring made of copper is 30% -50% and the elongation of the metal ring made of nickel is 10% -30% under the action of the corner stroke, which are both far greater than the required deformation amount, and the effect of completely filling the sealing groove can be achieved. A better sealing effect is obtained when the angle of the corners is 70 deg..

When the first structural member 01 and the second structural member 02 are connected in a plane contact friction mode, the mode requires that the surface roughness of the contact surfaces of the two structural members reaches below 2 mu m, the part processing requirement is high, and the processing cost is also high; when the sealing groove and the metal ring 05 are matched and sealed, the requirement on the surface roughness of a structural part can be relaxed to 0.7-0.9 mu m, and the requirement level of common parts is met, so that the part processing mode can be changed, the part processing cost can be reduced, the part processing and assembling process can be simplified, the realization is easier, and the cost is more economical and saved.

In a specific implementation process, after the fastening member is pressed, the first structural member 01 and the second structural member 02 of the bearing jointly press the metal ring 05, and the metal ring 05 is deformed to form the sealing ring 04 in the sealing groove and is filled in the sealing groove. The metal ring 05 is made of a ductile material, and the sealing ring 04 positioned in the sealing groove can generate certain prestress under the fastening force, so that the processing defect of a structural member of the bearing is overcome, and the sealing requirement is met. At this time, the first structural member 01 and the second structural member 02 should be closely attached so that the side of the sealing ring 04 close to the rotating shaft 03 does not contact with the liquid metal, thereby preventing the sealing ring 04 from being corroded. In a compressed state, when the cross section of the sealing groove is triangular, the inner side of the sealing ring 04, i.e., the side of the sealing ring close to the rotating shaft 03, is extruded into a sharp shape, so as to reduce the contact area between the sealing ring 04 and the liquid metal as much as possible.

Further, since the material used for the sealing ring 04 is generally a material that is not resistant to corrosion by liquid metal, the reaction between the two is more severe especially at high temperatures. In order to solve the problems, the inner diameter of the sealing groove is 0.5-2 mm away from the edge of the rotating shaft 03. That is to say, the contact surfaces of the first structural member 01 and the second structural member 02 are provided with the ring surfaces with the ring width of 0.5 mm-2 mm, the ring surfaces can play a limiting role on one hand, when the two structural members are fastened, the surfaces of the two opposite structural members are tightly attached and then are assembled in place by using the fastening piece, the axial height of the bearing assembly is ensured, and the filling effect of the sealing groove is also ensured; on the other hand, after the bearing is fastened in place, the circular ring surfaces on the two structural parts are tightly attached together, so that the liquid metal and the sealing ring 04 are isolated, and the liquid metal is prevented from corroding the sealing ring 04 under the working condition.

In a specific embodiment, the invention also provides a liquid metal bearing assembly method, wherein the liquid metal bearing comprises a first structural component 01 and a second structural component 02 combined and fixed with the first structural component 01; at least one sealing groove for accommodating a sealing ring is arranged between the first structural member 01 and the second structural member 02, and the cross section of the sealing groove comprises two inclined edges gradually gathered towards the rotating shaft; the width of the metal ring 05 is smaller than or equal to that of the sealing groove, the volume of the metal ring 05 is 5% -30% larger than that of the sealing groove, the first component 01 and the second component 02 are in friction contact and are tightly fixed through a fastening mode, and the metal ring 05 forms a sealing ring 04 in the sealing groove. It can be understood that the metal ring 05 becomes the sealing ring 04 after being inserted into the sealing groove and being pressed and fixed by the first structural member 01 and the second structural member 02.

In the present embodiment, the sealing ring 04 is closely contacted with the sealing groove on the inner side and has a gap with the sealing groove on the outer side. Through the above setting, the inboard and the seal groove of sealing ring 04 closely laminate as sealed face, prevent that liquid metal from leaking, and the clearance between the sealing ring 04 outside and the seal groove can be used for when liquid metal leaks, stores the liquid metal of revealing, prevents that it from directly getting into the X-ray tube, causes the damage.

In conclusion, the sealing groove and the metal ring are matched to form the sealing ring so as to seal the liquid metal bearing, and the processing difficulty of the first structural component and the second structural component can be obviously reduced. Usually, the working speed of the liquid metal bearing can reach 10000 r/min, the requirements on the conditions of mechanical performance, liquid metal sealing and the like are very high, the requirements on the dimensional tolerance, the form and position tolerance, the surface roughness of the bearing surface, the surface roughness of the sealing surface and the like of the bearing are also very high, and the processing cost is also very high. The invention has good bearing sealing effect by adopting a mode that the metal ring is extruded to form the sealing ring in the sealing groove, and can be independently used as a sealing structure of the bearing, so that the processing requirement of the sealing surface of the bearing is reduced, and the cost can be effectively reduced; in addition, the complex processes such as coating on the surface of the bearing are reduced, so that the processing process of the bearing is simplified. Therefore, the processing cost of the liquid metal bearing adopting the sealing mode is greatly reduced, and the production period is also shortened.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims

1. A liquid metal bearing, comprising:

a first structural member;

a seal ring made of a ductile metallic material;

2. The liquid metal bearing of claim 1, wherein the seal groove comprises a first groove portion disposed in a first component and a second groove portion disposed in a second component.

3. A liquid metal bearing according to claim 2, wherein the first and second groove cross-sectional shapes are symmetrically disposed about the contact surface.

4. The liquid metal bearing of claim 1, wherein the seal groove has a triangular or trapezoidal cross-sectional shape.

5. A liquid metal bearing according to claim 1, wherein the cross-sectional shape of the seal groove comprises a head and a wedge-shaped tail in communication with the head.

6. A liquid metal bearing according to claim 5, wherein the nose is rectangular, the depth of the rectangle being the same as the depth of the wedge-shaped tail.

7. A liquid metal bearing according to claim 1, wherein the two oblique edges of the sealing groove form an angle < 60 ° to 80 °.

8. A liquid metal bearing according to claim 1, wherein the inside diameter of the seal groove is 0.5mm to 2mm from the shaft edge.

9. The liquid metal bearing assembly method is characterized by comprising a first structural component and a second structural component which is fixedly combined with the first structural component;

10. A liquid metal bearing assembly method as claimed in claim 9, wherein the sealing ring is closely contacted with the sealing groove on the inner side and has a gap with the sealing groove on the outer side.