Multistage roots pump shaft

Abstract

The utility model provides a pump shaft of a multistage roots pump, and aims to solve the technical problems of large cutting output and low processing efficiency in pump shaft preparation in the prior art. The pump shaft comprises: a main shaft, the axis of which is a straight line; through holes are formed in the middles of the rotor monomers, the rotor monomers are all arranged on the main shaft in a sleeving manner, a plurality of convex surfaces and a plurality of concave surfaces which are arranged at intervals are arranged on the outer wheel surface of each rotor monomer, the concave surfaces and the convex surfaces are arc-shaped surfaces, and all the convex surfaces are uniformly distributed in the circumferential direction; the plurality of sleeve pieces are in a hollow cylindrical shape and are all arranged on the main shaft in a sleeving manner; wherein the number of the concave surfaces on the rotor single bodies is equal to the number of the convex surfaces on the rotor single bodies, one external member is arranged between every two adjacent rotor single bodies, and the rotor single bodies are in interference fit with the main shaft. The rotor monomer and the main shaft respectively select blanks to be independently machined, then the pump shaft is manufactured in an assembling mode, the pump shaft is manufactured in the mode of independently machining the rotor monomer and the main shaft, the cutting amount can be reduced by nearly 50%, and therefore the production efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of shaft assembly, in particular to a multi-stage Roots pump shaft. Background Art

[0002] In the current vacuum pump market, multi-stage Roots rotors are mostly made of integral cast bars during the manufacturing process, and then cut. The main process flow is: the blank is roughly cut from the bar to form the appearance - stress relief and tempering - semi-finishing the Roots contour - finishing the center shaft end face and hole system - finishing the axial part size - finishing the Roots contour - fine grinding the shaft neck - fine machining the thread - finished product burr and dynamic balancing treatment.

[0003] Since the production method of the prior art is one-piece manufacturing, the blank volume required for processing is large, resulting in a large amount of cutting and low processing efficiency. Utility Model Content

[0004] In view of the technical problems of large amount of cutting and low processing efficiency in the preparation of pump shafts in the above-mentioned prior art, the present invention provides a multi-stage Roots pump shaft and a manufacturing method thereof, which has the advantages of small amount of cutting and high processing efficiency.

[0005] The technical solution of the utility model is:

[0006] A multi-stage Roots pump shaft, comprising:

[0007] the principal axis, whose axis is a straight line;

[0008] A plurality of rotor units, each having a through hole in the middle, and all being sleeved on the main shaft, with a plurality of convex surfaces and a plurality of concave surfaces spaced apart on the outer surface thereof, wherein the concave and convex surfaces are both arc-shaped, and all the convex surfaces are evenly distributed in the circumferential direction;

[0009] A plurality of sets of hollow cylindrical components are all sleeved on the main shaft;

[0010] The number of concave surfaces and convex surfaces on the rotor monomer is equal, one of the sleeves is provided between two adjacent rotor monomers, and the rotor monomer and the main shaft are in interference fit.

[0011] Optionally, the main shaft is provided with a plurality of rotor groups, each of the rotor groups includes a plurality of identical rotor monomers, and the rotor monomers in each rotor group have the same number of concave surfaces.

[0012] Optionally, the concave surfaces on all rotor units in the same rotor group are arranged on the same cylindrical curved surface.

[0013] Optionally, all rotor units in the rotor group have the same rotation radius when rotating.

[0014] Optionally, all the rotor groups are arranged in sequence on the main shaft according to the number of concave surfaces of their rotor units.

[0015] Optionally, the main shaft is a stepped shaft.

[0016] Optionally, a transition surface is provided at the connection between the concave surface and the convex surface, and two ends of the transition surface are tangentially connected to the concave surface and the convex surface respectively.

[0017] Optionally, both ends of the kit are provided with a protrusion structure, and the side of the rotor unit is provided with a groove structure, and the protrusion structure can be placed in the groove structure.

[0018] Optionally, a positioning ring is provided on one end of the pump shaft.

[0019] Optionally, a plurality of protruding structures are provided at the end of the sleeve, and all of the protruding structures are distributed in a ring shape to form a ring-shaped tooth structure;

[0020] The side of the rotor unit has a plurality of groove structures matching the tooth-shaped structures.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The rotor unit and the main shaft are separately processed as blanks, and then the pump shaft is prepared by assembly. Preparing the pump shaft by separately processing the rotor unit and the main shaft can reduce the cutting amount by nearly 50%, thereby improving production efficiency.

[0023] Furthermore, during assembly, the rotor unit is heated to enlarge the through-hole in its center. The heated rotor unit is then placed over the main shaft and cooled, achieving an interference fit between the rotor unit and the main shaft. This assembly method, unlike traditional keyed connections, eliminates the need for keyway installation and key installation in the rotor unit and main shaft. Furthermore, the interference fit ensures a tight connection between the pump shaft and the rotor unit, preventing vibration when the main shaft drives the rotor unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0026] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0027] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art will recognize the application of other processes and / or the use of other materials.

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Example 1: Figure 1 As shown, this embodiment discloses a multi-stage Roots pump shaft, comprising a main shaft 10, a rotor unit 21, and a sleeve 30. Specifically, the axis of the main shaft 10 extends in a straight line. The main shaft 10 can be either a straight or stepped shaft. A positioning ring 11 can also be provided at one end of the main shaft 10 to facilitate the installation and positioning of the rotor unit 21 and the sleeve 30. The sleeve 30 is hollow cylindrical, and the rotor unit 21 has a through hole in the middle. There are multiple rotor units 21 and multiple sleeves 30.

[0030] The rotor monomer 21 is a columnar structure, and has a plurality of concave surfaces 211 and a plurality of convex surfaces 212 on the outer ring surface of the rotor monomer 21. The number of concave surfaces 211 and convex surfaces 212 is the same, and there are at least two of them. At the same time, the concave surfaces 211 and convex surfaces 212 on the rotor monomer 21 are arranged at intervals, and the convex surfaces 212 and concave surfaces 211 on the rotor monomer 21 are both arc-shaped structures.

[0031] The rotor monomers 21 are sleeved on the main shaft 10 , and at least one sleeve 30 is provided between two adjacent rotor monomers 21 , so that one side surface of the rotor monomer 21 abuts against one end surface of the sleeve 30 , thereby separating adjacent rotor monomers 21 by a certain distance.

[0032] The multi-stage Roots pump has two pump shafts inside. The two pump shafts have the same structure. After the pump shafts are assembled in the Roots pump, the rotor monomers 21 on the two pump shafts are in a mutually meshing state. That is, the convex surface 212 of a rotor monomer 21 on one pump shaft is located within the concave surface 211 of a rotor monomer 21 on the other pump shaft. Then, the purpose of vacuuming is achieved by the opposite high-speed rotation of the two pump shafts.

[0033] Preferably, the location where the outer surface of the main shaft 10 connects to the rotor unit 21 can be cylindrical or polygonal. If the outer surface of the main shaft 10 is cylindrical, the through hole in the rotor unit 21 is a circular hole. If the outer surface of the main shaft 10 is polygonal, the through hole in the rotor unit 21 is a polygonal hole, and the number of sides of the through hole is equal to the number of sides of the outer surface of the main shaft 10.

[0034] The size of the outer axial surface of the main shaft 10 is larger than the size of the through hole in the middle of the rotor monomer 21. The rotor monomer 21 and the main shaft 10 are interference fitted, so that the rotor monomer 21 and the main shaft 10 are in a tightly connected state.

[0035] In this embodiment, the rotor unit 21 and the main shaft 10 are selected as blanks and processed separately, and then the pump shaft is prepared by assembly. By preparing the pump shaft by separately processing the rotor unit 21 and the main shaft 10, the cutting amount can be reduced by nearly 50%, thereby improving production efficiency.

[0036] In one specific embodiment:

[0037] In a specific production structure, a plurality of rotor groups 20 are arranged on the main shaft 10 of the multi-stage Roots pump shaft, and each rotor group 20 includes a plurality of rotor monomers 21. The number of concave surfaces 211 of all rotor monomers 21 in each rotor group 20 is the same, and the number of concave surfaces 211 of the rotor monomers 21 in different rotor groups 20 is different.

[0038] Specifically, such as Figure 1 As shown, the rotor units 21 in one rotor assembly 20 have five concave surfaces 211, the rotor units 21 in another rotor assembly 20 have four concave surfaces 211, and another rotor assembly 20 has two concave surfaces 211. When all rotor assemblies 20 are assembled on the spindle 10, the concave surfaces 211 of all rotor units 21 in each rotor assembly 20 are aligned with each other (i.e., all concave surfaces 211 are on the same cylindrical arc surface).

[0039] The rotor assembly 20 with five concave surfaces 211 on its rotor unit 21 is the first assembly, the rotor assembly 20 with four concave surfaces 211 on its rotor unit 21 is the second assembly, and the rotor assembly 20 with two concave surfaces 211 on its rotor unit 21 is the third assembly. The order of arrangement of the first, second, and third assemblies on the spindle 10 is as follows: along the axis of the spindle 10, the first assembly is mounted on one end of the spindle 10, the second assembly is mounted between the first and third assemblies, and the third assembly is mounted on the other end of the spindle 10. The installation pattern is as follows: All rotor assemblies 20 are arranged on the spindle 10 in order of the number of concave surfaces 211 on their internal rotor units 21.

[0040] When all the rotor units 21 are mounted on the main shaft 10 and the main shaft 10 drives all the rotor units 21 to rotate, the radius of the space occupied by all the rotor units 21 during rotation is the same.

[0041] In another specific embodiment:

[0042] On the rotor unit 21, a transition surface 213 is provided at the connection between the concave surface 211 and the convex surface 212. The two ends of the transition surface 213 are tangentially connected to the concave surface 211 and the curved surface respectively. The concave surface 211, the transition surface 213 and the convex surface 212 together make the outer ring surface of the rotor unit 21 present a smooth surface.

[0043] In another specific embodiment:

[0044] In order to improve the connection strength between the kit 30 and the rotor monomer 21, and to prevent the single rotor monomer 21 from sliding due to assembly reasons, a protrusion structure (not shown in the figure) is provided at both ends of the kit 30, and then a groove structure (not shown in the figure) is provided on the side of the rotor monomer 21. The characteristic that the protrusion structure can be placed in the groove structure is utilized to establish a connection relationship between the kit 30 and the rotor monomer 21.

[0045] Preferably, the end of the kit 30 is provided with several protrusion structures, all of which are distributed in a ring shape and constitute an annular tooth structure. Similarly, several annularly distributed groove structures are provided on the side of the rotor monomer 21, and the protrusion structure of the tooth structure matches all the groove structures, thereby increasing the connection strength between the kit 30 and the rotor monomer 21.

[0046] Example 2: This example discloses a method for manufacturing a multi-stage Roots pump shaft. The method is primarily used to prepare the pump shaft described in Example 1. The pump shaft, as described in Example 1, comprises a main shaft 10, a sleeve 30, and a rotor unit 21. The rotor unit 21 and the sleeve 30 are mounted on the main shaft 10. The specific manufacturing method includes:

[0047] First, select suitable blanks for the rotor unit 21, spindle 10, and sleeve 30. For the spindle 10, choose a cylindrical, elongated metal material. For the rotor unit 21, choose either a round or cylindrical metal material. For the sleeve 30, preferably a tubular metal material.

[0048] After the blank is selected, it is processed by turning, milling or grinding to form the corresponding blank into a rotor unit 21, a main shaft 10 or a sleeve 30.

[0049] During the assembly process, the rotor unit 21 is heated and then placed onto the spindle 10. The rotor unit 21 and the sleeve 30 are then installed sequentially on the spindle 10, with the rotor unit 21 and the sleeve 30 spaced one after the other. After the rotor unit 21 is installed on the spindle 10, the rotor unit 21 and the spindle 10 are cooled to room temperature.

[0050] Preferably, the rotor unit 21 and the sleeve 30 are heated together by means of induction pulses, and the heating temperature is between 150° C. and 400° C., and the heating time is between 5s and 30s.

[0051] When the temperature is lower than 150°C and the heating time is 5s-30s, or when the temperature is between 150°C and 400°C and the heating time is less than 5s, the rotor monomer 21 cannot expand due to the heat. Therefore, when the heating temperature is lower than 150°C, the size of the through hole in the middle of the rotor monomer 21 cannot expand to a size larger than the shaft diameter of the main shaft 10, resulting in the inability to assemble.

[0052] When the temperature is greater than 400°C and the heating time is 5s-30s, or when the temperature is between 150°C and 400°C and the heating time is greater than 30s, the metallographic structure inside the rotor monomer 21 will change, thereby affecting the strength of the rotor monomer 21 material and reducing the life of the rotor monomer 21 during use.

[0053] In actual production, the rotor monomer 21 and the sleeve 30 are heated together at a temperature of 330°C and a heating time of 15 seconds. At this time, the through-hole size in the rotor monomer 21 can be just larger than the outer diameter of the main shaft 10, so that the rotor monomer 21 can be just mounted on the main shaft 10 and the cooling time can be effectively shortened.

[0054] Preferably, when machining the main shaft 10 , after selecting a suitable blank, rough machining is performed. The main shaft 10 can be rough machined by milling, turning or grinding.

[0055] Rough machining reserves allowance for fine machining, and then the rough finished product is tempered to relieve stress.

[0056] Then, one end portion is fine-machined to ensure the flatness of the end portion and the perpendicularity to the axis. After fine-machined, the end face is used as the reference surface to fine-machine the axial surface of the main shaft 10.

[0057] When the axial surface of the main shaft 10 is finely machined, the position on the outer axial surface of the main shaft 10 where the rotor unit 21 is mounted is mainly machined, and the position where the kit 30 is mounted may reduce the machining accuracy.

[0058] During the machining process, the straightness error of the main shaft 10 should be less than or equal to 0.05 mm, and the coaxiality error of the axial surfaces of all the rotor units 21 mounted on the main shaft 10 should be less than or equal to 0.01 mm.

[0059] Finally, the spindle 10 is processed, and burrs are removed and dynamic balancing is performed.

[0060] Preferably, when machining the rotor unit 21 , a blank of the rotor unit 21 is selected, and then the outer contour and the inner through hole are roughly machined.

[0061] The through hole in the middle of the rotor body 21 is finely machined, and then positioning is performed based on the through hole, and the outer contour is finely machined based on the through hole.

[0062] The machined rotor body 21 is subjected to quenching treatment.

[0063] Finally, the heated rotor unit 21 is assembled on the main shaft 10 .

[0064] In this embodiment, the rotor unit 21 is heated to enlarge the size of the through-hole in its center. The heated rotor unit 21 is then fitted over the spindle 10 and cooled, achieving an interference fit between the rotor unit 21 and the spindle 10. This assembly method, unlike traditional keyed connections, eliminates the need for keyway installation and key installation in the rotor unit 21 and spindle 10. Furthermore, the interference fit ensures a tight connection between the pump shaft and the rotor unit 21, preventing vibration in the rotor unit 21 when the spindle 10 drives the rotor unit 21.

[0065] In one preferred embodiment:

[0066] During the assembly process, the processed main shaft 10 is first fixed on a special fixture, and then all the rotor units 21 and all the kits 30 are installed on the main shaft 10 one by one along a straight line using assembly tools, and it is ensured that during the installation process, the axis of the main shaft 10 and the axis of the through hole in the middle of the rotor unit 21 are on the same straight line.

[0067] The specific assembly method is as follows: After the main shaft 10 is fixed, the first rotor unit 21 to be installed is heated to a predetermined temperature, then installed on the main shaft 10. The main shaft 10 and the rotor unit 21 are cooled to room temperature by air cooling. The next kit 30 is then assembled in sequence, and all rotor units 21 and kits 30 are installed in sequence.

[0068] While the previously installed rotor unit 21 is being cooled, the next rotor unit 21 or the kit 30 to be installed may be heated, thereby improving assembly efficiency.

[0069] In addition, in the present application, the rotor unit 21 and the kit 30 can be an integral whole, produced and processed from a blank. During the assembly process, the integrated rotor unit 21 and the kit 30 are heated to 150°C-400°C and then assembled to the main shaft 10.

[0070] In this embodiment, when installing the rotor monomer 21, cooling is performed immediately after the installation of one rotor monomer 21 is completed, so that the single rotor monomer 21 can be immediately fixedly installed at the specified position of the main shaft 10, avoiding affecting the rotor monomer 21 at a determined position when installing other rotor monomers 21 or the kit 30, thereby affecting its position and reducing assembly errors.

[0071] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A multi-stage Roots pump shaft, characterized in that: include: the principal axis, whose axis is a straight line; A plurality of rotor units, each having a through hole in the middle, and all being sleeved on the main shaft, with a plurality of convex surfaces and a plurality of concave surfaces spaced apart on the outer surface thereof, wherein the concave and convex surfaces are both arc-shaped, and all the convex surfaces are evenly distributed in the circumferential direction; A plurality of sets of hollow cylindrical components are all sleeved on the main shaft; The number of concave surfaces and convex surfaces on the rotor monomer is equal, one of the sleeves is provided between two adjacent rotor monomers, and the rotor monomer and the main shaft are in interference fit.

2. The multi-stage Roots pump shaft according to claim 1, characterized in that: The main shaft is provided with a plurality of rotor groups, each of the rotor groups includes a plurality of identical rotor monomers, and the rotor monomers in each rotor group have the same number of concave surfaces.

3. The multi-stage Roots pump shaft according to claim 2, characterized in that: The concave surfaces on all rotor units in the same rotor group are arranged on the same cylindrical curved surface.

4. The multi-stage Roots pump shaft according to claim 2, characterized in that: When the rotor units in all the rotor groups rotate, the rotation radius is the same.

5. The multi-stage Roots pump shaft according to claim 2, characterized in that: All the rotor groups are arranged in sequence on the main shaft according to the number of concave surfaces of their rotor units.

6. The multi-stage Roots pump shaft according to claim 1, characterized in that: The main shaft is a stepped shaft.

7. The multi-stage Roots pump shaft according to claim 1, characterized in that: A transition surface is provided at the connection between the concave surface and the convex surface, and two ends of the transition surface are tangentially connected to the concave surface and the convex surface respectively.

8. The multi-stage Roots pump shaft according to any one of claims 1 to 7, characterized in that: Both ends of the kit are provided with a protruding structure, and the side of the rotor unit is provided with a groove structure, and the protruding structure can be placed in the groove structure.

9. The multi-stage Roots pump shaft according to any one of claims 1 to 7, characterized in that: A positioning ring is provided on one end of the pump shaft.

10. The multi-stage Roots pump shaft according to claim 8, characterized in that: The end of the sleeve is provided with a plurality of protruding structures, all of which are distributed in a ring shape and form a ring-shaped tooth structure; The side of the rotor unit has a plurality of groove structures matching the tooth-shaped structures.

Images