Vacuumizing system and pipe sealing machine with same

Abstract

The invention discloses a vacuumizing system and a pipe sealing machine with the vacuumizing system, and relates to the technical field of vacuum quartz pipe sealing machines, the vacuumizing system comprises a molecular pump unit, the molecular pump unit comprises a molecular pump and a backing pump, an isolating valve is arranged between the molecular pump and the backing pump, the isolating valve comprises a shell, an air inlet pipe and an air outlet pipe are arranged on the shell, and the shell is provided with an air inlet pipe and an air outlet pipe. A one-way assembly is arranged in the air outlet pipe; through the arrangement of the fixed cylinder, the baffle, the first elastic piece, the annular plate and the like, when pump pressure drop, power failure and faults occur in the front-stage pump, most backflow gas is blocked on the outer side of the fixed cylinder, only a small amount of gas enters the fixed cylinder, meanwhile, the baffle makes contact with the sealing plate rapidly under the action of the first elastic piece, and therefore the sealing effect is improved. The gas entering the fixed cylinder pushes the baffle in the forward direction, so that the response speed of the baffle is higher, the influence of backflow gas on the molecular pump is reduced or even avoided, and the response speed of the isolating valve is increased.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum quartz tube sealing machines, and in particular to a vacuum pumping system and a tube sealing machine having the same. Background Art

[0002] The vacuum quartz tube sealing machine is a device specially used for vacuum packaging of quartz tubes. It can ensure that the air or other gases in the quartz tube are extracted without introducing impurities, and the quartz tube is sealed under vacuum. It is mainly composed of vacuum system, heating system, cooling system, support and positioning system and control system. Among them, the vacuum system includes components such as the fore pump, molecular pump, vacuum gauge and valve.

[0003] Due to the limitations of molecular pumps, they need to be used in conjunction with fore-stage pumps during vacuum operation; at the same time, an isolation valve (also called fore-stage valve) needs to be set between the molecular pump and the fore-stage pump to prevent the fore-stage pump and the molecular pump from being separated in time in the event of a power outage or failure, thereby preventing the molecular pump from being subjected to air pressure shock and gas contamination.

[0004] If the foreline pump fails to effectively reduce the pressure, the gas flow entering the molecular pump will be too large, which may cause the molecular pump to lose efficiency or even fail to work properly. In addition, if the foreline pump fails to maintain a sufficient pumping rate, oil vapor or other contaminants may diffuse from the low vacuum side to the high vacuum side, causing contamination.

[0005] The Chinese patent application number 202110484899.9 discloses an automatic opening and closing differential pressure valve to prevent backflow of the molecular pump's fore-stage pump. Although the invention uses the gas pressure difference to realize the automatic opening and closing of the valve, it cuts off the connection between the fore-stage vacuum and the molecular pump when the fore-stage vacuum pump fails and the vacuum deteriorates, preventing the fore-stage high pressure from impacting the molecular pump blades and avoiding gas contamination of the vacuum chamber. However, there are at least the following problems: In actual use, the opening and closing module has a long response time when moving upward and its sensitivity is not high. Therefore, during this process, a lot of gas still enters the molecular pump through the pressure differential valve, resulting in unsatisfactory gas backflow prevention effect and other problems.

[0006] In addition, although existing molecular pump units usually have filter components to filter impurities and other pollutants carried in the backflow gas, the isolation valve itself does not have this function. When the filtering accuracy of the filter component decreases, the isolation valve cannot perform additional filtering on the gas, resulting in a lack of corresponding emergency remedial measures for the vacuum system.

[0007] To this end, the present invention proposes a vacuum system and a tube sealing machine having the same to solve the above problems. Summary of the invention

[0008] The object of the present invention is to provide a vacuum pumping system and a tube sealing machine having the same, so as to solve the technical problems of the slow response speed of the isolation valve and the lack of emergency measures for gas filtration proposed in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a vacuum pumping system, comprising a molecular pump unit, wherein the molecular pump unit comprises a molecular pump and a front-stage pump, and an isolation valve is provided between the molecular pump and the front-stage pump; The isolation valve includes a shell, on which an air inlet pipe and an air outlet pipe are arranged, the air inlet pipe is connected to the exhaust end of the molecular pump through a pipeline, the air outlet pipe is connected to the air inlet end of the front-stage pump through a pipeline, a sealing member is arranged on the top of the shell, a knob is arranged on the sealing member, a cavity is formed between the sealing member and the shell, a coaxially arranged piston column is slidably arranged in the cavity, the piston column divides the cavity into an active cavity and a back pressure cavity, an air hole is opened through the circumferential side of the piston column, a bypass pipe connected to the back pressure cavity is arranged on the side wall of the air outlet pipe, a one-way component is arranged in the air outlet pipe, and the one-way component is located between the piston column and the bypass pipe.

[0010] Preferably, the one-way component includes a fixed cylinder coaxially arranged in the air outlet pipe, the fixed cylinder is a cylindrical structure with openings at both ends, and the fixed cylinder includes a horizontal section and an inclined section, the cross-sectional diameter of the inclined section of the fixed cylinder changes in a step-like manner along the length direction of the air outlet pipe, one end of the fixed cylinder close to the piston column is the air inlet end, and the other end is the air outlet end, and the diameter of the air inlet end is greater than the diameter of the air outlet end.

[0011] Preferably, an annular sealing plate is coaxially fixed on the inner wall of the air inlet end, a baffle is coaxially arranged on one side of the sealing plate, the baffle moves in the horizontal section of the fixed cylinder, an annular plate is fixedly connected to the inner wall of the fixed cylinder, and a first elastic member is arranged between the baffle and the annular plate.

[0012] Preferably, a rotating cylinder is rotatably connected to the outer wall of the fixed cylinder, and a plurality of first through holes and second through holes evenly distributed around the circumference are respectively provided on the circumferential sides of the fixed cylinder and the rotating cylinder, and the first through holes and the second through holes are staggered, a connecting rod is coaxially provided on the baffle, a connecting hole matching the connecting rod is provided at one end of the rotating cylinder, a spiral track is provided on the circumferential side of the connecting rod, and a connecting block matching the spiral track is fixedly connected to the inner wall of the connecting hole.

[0013] Preferably, a filter screen is provided on the outer wall of the circumferential side of the fixed cylinder.

[0014] Preferably, an adjusting column which slides up and down is provided in the movable cavity, an adjusting plate is coaxially fixed to the bottom end of the adjusting column located in the movable cavity, a second elastic member is provided between the adjusting plate and the piston column, an air groove is penetrated through the adjusting plate, an adjusting bolt is coaxially fixed on the knob, one end of the adjusting column away from the adjusting plate is threadedly connected to the adjusting bolt, a limiting block is provided on the circumferential side of the adjusting column, and a limiting groove matching the limiting block is provided on the inner wall of the sealing member.

[0015] Preferably, the sealing member comprises a sealing gasket coaxially arranged on the housing, a sealing sleeve is arranged above the sealing gasket, the adjusting column is sealingly and slidingly connected to the sealing sleeve, and the knob is rotatably connected to the top of the sealing sleeve.

[0016] Preferably, the molecular pump unit further comprises a control box, in which a control unit is arranged.

[0017] The present invention also provides a tube sealing machine, comprising the above-mentioned vacuum pumping system and a tube sealing machine body, the tube sealing machine body comprising a workbench and an operating table located on one side of the top of the workbench, the molecular pump unit is located in the operating table, and a control panel is provided on the operating table, and the control panel is connected to the control box by electrical signals.

[0018] Preferably, a tube sealing assembly is provided on the workbench, and the tube sealing assembly comprises a clamping element and a heating element.

[0019] The beneficial effects of the present invention are: 1. The present invention is provided with a fixed cylinder, a baffle, a first elastic member and an annular plate. When the pump pressure of the front-stage pump drops, a power outage or a fault occurs, most of the backflow gas is blocked on the outside of the fixed cylinder, and only a small amount of gas enters the inside of the fixed cylinder. At the same time, the baffle quickly contacts the sealing plate under the action of the first elastic member, and the gas entering the fixed cylinder exerts a positive push on the baffle, making the response speed of the baffle faster, thereby reducing or even avoiding the influence of the backflow gas on the molecular pump and improving the response speed of the isolation valve.

[0020] 2. The present invention is configured by a connecting rod, a spiral track, a connecting block and a rotating cylinder. When the baffle is in an open state, the first through hole is connected to the second through hole, thereby increasing the flow rate of gas passing through the one-way component. This not only avoids the loud noise generated by gas acceleration, but also reduces the wear of the fixed cylinder. When used in the laboratory, it can effectively reduce the impact of noise on the staff, extend the service life of the one-way component, and reduce the maintenance burden of the staff.

[0021] 3. The present invention is provided with baffles, drums and filters. If the filtering accuracy of the filter element in the molecular pump unit decreases, the filter can perform secondary filtration on the oil vapor and other pollutants in the gas when the backflow gas passes through the one-way component, so as to prevent these pollutants from causing damage to the vacuum chamber of the molecular pump, so that the isolation valve has effective emergency remedial measures; in addition, during each rotation of the drum and opening of the baffle, the inner wall of the drum and the gas ejected after the baffle is opened will clean the filter, thereby extending the service life of the filter and improving the universality and reliability of the one-way component. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic diagram of the overall structure of a vacuum pumping system and a tube sealing machine having the same.

[0023] Figure 2 It is a structural schematic diagram of the molecular pump unit of the present invention.

[0024] Figure 3 It is a schematic structural diagram of the isolation valve of the present invention.

[0025] Figure 4 It is a schematic plan cross-sectional view of the isolation valve of the present invention in a closed state.

[0026] Figure 5 It is a schematic plan cross-sectional view of the isolation valve of the present invention in a conducting state.

[0027] Figure 6 It is a schematic diagram of the three-dimensional structure of the one-way component of the present invention.

[0028] Figure 7 It is a schematic plan cross-sectional view of the fixing cylinder of the present invention.

[0029] Figure 8 It is a schematic diagram of disassembly of the one-way component of the present invention.

[0030] Fig. 9 It is a schematic plan cross-sectional view of the one-way component of the present invention in a closed state.

[0031] Fig.10 It is a schematic plan cross-sectional view of the one-way component of the present invention in a conducting state.

[0032] Fig.11 It is a schematic structural diagram of the spiral track of the present invention.

[0033] The accompanying drawings are marked as follows: 1. Tube sealing machine body; 11. Workbench; 12. Operating table; 2. Molecular pump unit; 21. Molecular pump; 22. Fore pump; 23. Control box; 3. Isolation valve; 301. Active chamber; 302. Back pressure chamber; 31. Shell; 32. Inlet pipe; 33. Outlet pipe; 34. Seal; 341. Sealing gasket; 342. Sealing sleeve; 35. Knob; 36. Piston rod; 361. Air hole; 37. Bypass pipe; 4. One-way assembly; 41. Fixed cylinder; 411. First through hole; 42. Sealing plate; 43. Baffle; 44. Ring plate; 45. First elastic member; 46. Rotating cylinder; 461. Second through hole; 462. Connecting hole; 47. Connecting rod; 471. Spiral track; 5. Adjustment column; 51. Adjustment plate; 52. Second elastic member; 6. Adjustment plug; 7. Filter. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1 In the actual production process, due to the limitations of the molecular pump, it is necessary to use it with a fore-stage pump during vacuum operation; at the same time, an isolation valve needs to be set between the molecular pump and the fore-stage pump to prevent the fore-stage pump and the molecular pump from being separated in time when the fore-stage pump has a power outage or failure, thereby preventing the molecular pump from being subjected to air pressure shock and gas contamination; and the sensitivity of the existing isolation valve is relatively low, and in the process of preventing gas backflow, there is still a lot of gas entering the molecular pump through the isolation valve; this embodiment is specially invented to solve the above problems.

[0036] See also Figures 1 to 11 As shown, a vacuum pumping system according to an embodiment of the present invention includes a molecular pump unit 2 , wherein the molecular pump unit 2 includes a molecular pump 21 and a front pump 22 , and an isolation valve 3 is provided between the molecular pump 21 and the front pump 22 .

[0037] See also Figures 3 to 5As shown, the isolation valve 3 includes a shell 31, on which an air inlet pipe 32 and an air outlet pipe 33 are provided. The air inlet pipe 32 is connected to the exhaust end of the molecular pump 21 through a pipeline, and the air outlet pipe 33 is connected to the air inlet end of the front-stage pump 22 through a pipeline. A sealing member 34 is provided on the top of the shell 31, and a knob 35 is provided on the sealing member 34. A cavity is formed between the sealing member 34 and the shell 31, and a coaxially arranged piston column 36 is slidably arranged in the cavity. The piston column 36 divides the cavity into an active cavity 301 and a back pressure cavity 302. An air hole 361 is opened on the circumferential side of the piston column 36. A bypass pipe 37 connected to the back pressure cavity 302 is provided on the side wall of the air outlet pipe 33. A one-way component 4 is provided in the air outlet pipe 33, and the one-way component 4 is located between the piston column 36 and the bypass pipe 37.

[0038] See also Figure 6 and Figure 7 As shown, the one-way component 4 includes a fixed cylinder 41 coaxially arranged in the air outlet pipe 33, the fixed cylinder 41 is a cylindrical structure with openings at both ends, and the fixed cylinder 41 includes a horizontal section and an inclined section, the cross-sectional diameter of the inclined section of the fixed cylinder 41 changes in a step-like manner along the length direction of the air outlet pipe 33, one end of the fixed cylinder 41 close to the piston column 36 is the air inlet end, and the other end is the air outlet end, and the diameter of the air inlet end is greater than the diameter of the air outlet end.

[0039] See also Figure 7 As shown, an annular sealing plate 42 is coaxially fixed on the inner wall of the air inlet end, a baffle 43 is coaxially arranged on one side of the sealing plate 42, the baffle 43 moves in the horizontal section of the fixed cylinder 41, an annular plate 44 is fixedly connected to the inner wall of the fixed cylinder 41, and a first elastic member 45 is arranged between the baffle 43 and the annular plate 44.

[0040] See also Figure 4 and Figure 5 As shown, an adjusting column 5 which slides up and down is provided in the active cavity 301, an adjusting plate 51 is coaxially fixed to the bottom end of the adjusting column 5 located in the active cavity 301, a second elastic member 52 is provided between the adjusting plate 51 and the piston column 36, an air groove is provided through the adjusting plate 51, an adjusting bolt 6 is coaxially fixed to the knob 35, one end of the adjusting column 5 away from the adjusting plate 51 is threadedly connected to the adjusting bolt 6, a limiting block is provided on the circumferential side of the adjusting column 5, and a limiting groove matching the limiting block is provided on the inner wall of the sealing member 34.

[0041] See also Figure 4 and Figure 5 As shown, the seal 34 includes a sealing gasket 341 coaxially arranged on the housing 31, a sealing sleeve 342 is arranged above the sealing gasket 341, the adjustment column 5 is sealingly and slidingly connected to the sealing sleeve 342, and the knob 35 is rotatably connected to the top of the sealing sleeve 342.

[0042] See also Figure 2As shown, the molecular pump unit 2 further includes a control box 23, in which a control unit is disposed.

[0043] During use, when the worker seals the quartz tube, he sends an electrical signal to the control box 23 through the control panel on the operating table 12, and the front-stage pump 22 starts. During the vacuuming process of the front-stage pump 22, the air pressure in the back-pressure chamber 302 drops rapidly, and the piston column 36 moves downward under the action of negative pressure. The air hole 361 gradually connects with the air inlet pipe 32 and the air outlet pipe 33. As the front-stage pump 22 continues to work, the baffle 43 overcomes the elastic force of the first elastic member 45 and moves to the side away from the sealing plate 42. At this time, the one-way component 4 is in a conducting state, and the gas at the exhaust end of the molecular pump 21 enters the front-stage pump 22 through the air inlet pipe 32, the air hole 361, the one-way component 4 and the air outlet pipe 33, and is discharged by the front-stage pump 22.

[0044] When the front-stage pump 22 has a power outage or fails, a backflow phenomenon occurs, that is, the gas moves from the suction end of the front-stage pump 22 to the direction of the molecular pump 21. Due to the conical setting of the fixed cylinder 41, only a part of the backflow gas enters the interior of the fixed cylinder 41. After this part of the gas enters the fixed cylinder 41, the baffle 43 quickly adheres to the sealing plate 42 under the action of the first elastic member 45 to form a seal. Most of the backflow gas is isolated in the outlet pipe 33 by the one-way component 4. At the same time, the pressure in the back pressure chamber 302 gradually increases, and the piston column 36 moves upward under the push of the gas until the air hole 361 is completely sealed.

[0045] Through the arrangement of the fixed cylinder 41, the baffle 43, the first elastic member 45 and the annular plate 44, when the pump pressure of the front-stage pump 22 drops, the power fails or a fault occurs, most of the backflow gas is blocked on the outside of the fixed cylinder 41, and only a small part of the gas enters the inside of the fixed cylinder 41. At the same time, the baffle 43 quickly contacts the sealing plate 42 under the action of the first elastic member 45, and the gas entering the fixed cylinder 41 exerts a positive push on the movement of the baffle 43, so that the response speed of the baffle 43 is faster, thereby reducing or even avoiding the influence of the backflow gas on the molecular pump 21 and improving the response speed of the isolation valve 3.

[0046] Embodiment 2 It is found in actual use that when the gas moves from the molecular pump 21 to the pre-stage pump 22, due to the small diameter of the gas outlet end of the fixed cylinder 41, not only will there be a large noise when the gas passes through, but long-term use will also accelerate the wear of the outlet end; further improvements are made on the basis of the above embodiment.

[0047] See also Figures 8 to 11As shown, a rotating cylinder 46 is rotatably connected to the outer wall of the fixed cylinder 41, and a plurality of first through holes 411 and second through holes 461 uniformly distributed around the circumference are respectively provided on the circumferential sides of the fixed cylinder 41 and the rotating cylinder 46, and the first through holes 411 and the second through holes 461 are staggered, a connecting rod 47 is coaxially provided on the baffle 43, a connecting hole 462 matching the connecting rod 47 is provided at one end of the rotating cylinder 46, a spiral track 471 is provided on the circumferential side of the connecting rod 47, and a connecting block matching the spiral track 471 is fixedly connected to the inner wall of the connecting hole 462.

[0048] During use, when the baffle 43 moves toward the outlet end under the push of gas, the connecting rod 47 produces axial movement, and causes the rotating cylinder 46 to rotate a certain angle under the action of the connecting block and the spiral track 471, and the first through hole 411 on the fixed cylinder 41 is connected to the second through hole 461 on the rotating cylinder 46.

[0049] When the gas flows back, the baffle 43 is quickly re-sealed with the sealing plate 42 under the action of the first elastic member 45, and the connecting rod 47 moves axially again to reset the drum 46. At this time, the first through hole 411 and the second through hole 461 become staggered again.

[0050] At the same time, since the baffle 43 has a fast response speed, even if some gas passes through the second through hole 461 and the second through hole 461 into the interior of the fixed cylinder 41 at the initial stage of backflow, it will not affect the anti-backflow effect of the isolation valve 3 too much.

[0051] Through the arrangement of the connecting rod 47, the spiral track 471, the connecting block and the rotating cylinder 46, when the baffle 43 is in the open state, the first through hole 411 is connected with the second through hole 461, so as to increase the flow of gas through the one-way component 4, avoid the acceleration of the gas and generate loud noise, and reduce the wear of the fixed cylinder 41. When used in the laboratory, it can effectively avoid the impact of noise on the staff, extend the service life of the one-way component 4, and reduce the workload of the staff.

[0052] Embodiment 3 Although the existing molecular pump unit 2 is equipped with a filter element to filter impurities and other pollutants carried in the backflow gas, the isolation valve 3 does not have this function. When the filtering accuracy of the filter element decreases, the isolation valve 3 cannot filter the gas, resulting in a lack of corresponding emergency remedial measures for the vacuum system. In order to further enhance the filtering effect of the isolation valve 3 on the gas.

[0053] See also Fig. 9 and Fig.10 As shown, a filter screen 7 is provided on the outer wall of the circumferential side of the fixed cylinder 41 .

[0054] During use, when the gas passes through the one-way component 4, the oil vapor and pollutants carried inside it will be filtered out by the filter 7 to prevent these pollutants from entering the vacuum chamber of the molecular pump 21. At the same time, every time the drum 46 rotates once, the drum 46 will clean the surface of the filter 7.

[0055] At the same time, when the baffle 43 is opened, the gas pressure entering the fixed cylinder 41 is relatively high and the flow rate is relatively fast. After passing through the first through hole 411, the gas will impact the filter 7, thereby cleaning the filter 7 and further improving the use effect of the filter 7. At the same time, impurities and other pollutants in the second through hole 461 will also be washed away by the action of the gas.

[0056] Through the arrangement of the baffle 43, the drum 46 and the filter 7, if the filtering accuracy of the filter element arranged in the molecular pump unit 2 decreases, when the backflowing gas passes through the one-way component 4, the filter 7 performs secondary filtration on the oil vapor and pollutants in the gas, thereby preventing the pollutants from causing damage to the vacuum chamber of the molecular pump 21, so that the isolation valve 3 has an effective emergency remedial measure; at the same time, whenever the drum 46 rotates and when the baffle 43 is opened, the inner wall of the drum 46 and the gas ejected after the baffle 43 is opened will clean the filter 7, thereby extending the service life of the filter 7 and improving the universality of the one-way component 4.

[0057] Embodiment 4 See also Figure 1 As shown, the present invention also provides a tube sealing machine, which includes the above-mentioned vacuum pumping system, including a tube sealing machine body 1, the tube sealing machine body 1 includes a workbench 11 and an operating table 12 located on the top side of the workbench 11, the molecular pump unit 2 is located in the operating table 12, and a control panel is provided on the operating table 12, and the control panel is electrically connected to the control box 23.

[0058] See also Figure 1 As shown, a tube sealing assembly is provided on the workbench 11, and the tube sealing assembly includes a clamping member and a heating member. The clamping member is used to fix the quartz tube to be processed to ensure that it maintains the correct position during the tube sealing process. The heating member includes a hydrogen-oxygen machine and a spray gun. The spray gun surrounds the sealing position of the quartz tube and softens the quartz material by heating to facilitate the sealing operation. The clamping member and the heating member are both existing technologies and will not be described in detail.

[0059] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A vacuum pumping system, comprising a molecular pump unit (2), characterized in that: The molecular pump unit (2) comprises a molecular pump (21) and a front-stage pump (22), and an isolation valve (3) is provided between the molecular pump (21) and the front-stage pump (22); The isolation valve (3) comprises a housing (31), the housing (31) being provided with an air inlet pipe (32) and an air outlet pipe (33), the air inlet pipe (32) being connected to the exhaust end of the molecular pump (21) via a pipe, the air outlet pipe (33) being connected to the air inlet end of the fore pump (22) via a pipe, a sealing member (34) being provided at the top of the housing (31), a knob (35) being provided on the sealing member (34), and a cavity being formed between the sealing member (34) and the housing (31), A coaxially arranged piston column (36) is slidably arranged in the cavity, and the piston column (36) divides the cavity into an active cavity (301) and a back pressure cavity (302). An air hole (361) is provided through the circumferential side of the piston column (36). A bypass pipe (37) communicating with the back pressure cavity (302) is provided on the side wall of the air outlet pipe (33). A one-way component (4) is provided in the air outlet pipe (33), and the one-way component (4) is located between the piston column (36) and the bypass pipe (37).

2. A vacuum pumping system according to claim 1, characterized in that: The one-way component (4) comprises a fixed cylinder (41) coaxially arranged in the air outlet pipe (33); the fixed cylinder (41) is a cylindrical structure with two ends open, and the fixed cylinder (41) comprises a horizontal section and an inclined section; the cross-sectional diameter of the inclined section of the fixed cylinder (41) changes in a step-like manner along the length direction of the air outlet pipe (33); one end of the fixed cylinder (41) close to the piston rod (36) is an air inlet end, and the other end is an air outlet end, and the diameter of the air inlet end is greater than the diameter of the air outlet end.

3. A vacuum pumping system according to claim 2, characterized in that: An annular sealing plate (42) is coaxially fixed on the inner wall of the air inlet end, a baffle (43) is coaxially arranged on one side of the sealing plate (42), the baffle (43) moves in the horizontal section of the fixed cylinder (41), an annular plate (44) is fixedly connected to the inner wall of the fixed cylinder (41), and a first elastic member (45) is arranged between the baffle (43) and the annular plate (44).

4. A vacuum pumping system according to claim 3, characterized in that: A rotating cylinder (46) is rotatably connected to the outer wall of the fixed cylinder (41); a plurality of first through holes (411) and second through holes (461) evenly distributed around the circumference are respectively provided on the circumferential sides of the fixed cylinder (41) and the rotating cylinder (46); the first through holes (411) and the second through holes (461) are arranged in a staggered manner; a connecting rod (47) is coaxially arranged on the baffle plate (43); a connecting hole (462) matching the connecting rod (47) is provided at one end of the rotating cylinder (46); a spiral track (471) is provided on the circumferential side of the connecting rod (47); and a connecting block matching the spiral track (471) is fixedly connected to the inner wall of the connecting hole (462).

5. A vacuum pumping system according to claim 4, characterized in that: A filter screen (7) is provided on the outer wall of the circumferential side of the fixed cylinder (41).

6. A vacuum pumping system according to claim 5, characterized in that: An adjusting column (5) that slides up and down is arranged in the movable cavity (301); an adjusting plate (51) is coaxially fixed to the bottom end of the adjusting column (5) located in the movable cavity (301); a second elastic member (52) is arranged between the adjusting plate (51) and the piston column (36); an air groove is provided through the adjusting plate (51); an adjusting bolt (6) is coaxially fixed to the knob (35); one end of the adjusting column (5) away from the adjusting plate (51) is threadedly connected to the adjusting bolt (6); a limiting block is arranged on the circumferential side of the adjusting column (5); and a limiting groove matching the limiting block is arranged on the inner wall of the sealing member (34).

7. A vacuum pumping system according to claim 6, characterized in that: The sealing member (34) comprises a sealing gasket (341) coaxially arranged on the housing (31), a sealing sleeve (342) is arranged above the sealing gasket (341), the adjusting column (5) is sealingly and slidably connected to the sealing sleeve (342), and the knob (35) is rotatably connected to the top of the sealing sleeve (342).

8. A vacuum pumping system according to claim 7, characterized in that: The molecular pump unit (2) further comprises a control box (23), wherein a control unit is arranged in the control box (23).

9. A tube sealing machine, characterized in that: The invention comprises a vacuum pumping system and a tube sealing machine body (1) as claimed in any one of claims 1 to 8, wherein the tube sealing machine body (1) comprises a workbench (11) and an operating table (12) located on the top side of the workbench (11), the molecular pump unit (2) is located in the operating table (12), and a control panel is provided on the operating table (12), and the control panel is connected to a control box (23) via an electrical signal.

10. A tube sealing machine according to claim 9, characterized in that: A tube sealing assembly is arranged on the workbench (11), and the tube sealing assembly comprises a clamping element and a heating element.

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