Rotor for dry vacuum pump, forming method and vacuum pump

Abstract

The invention relates to the technical field of vacuum acquisition, and provides a rotor for a dry vacuum pump, a forming method and a vacuum pump, the rotor for the dry vacuum pump comprises: a body, a through hole being formed in the rotation center of the body; the convex part and the body are integrally arranged, and the convex part is arranged on the periphery of the body and extends towards one side far away from the through hole; wherein a first cavity is formed in the body, and the first cavity is arranged around at least part of the circumferential area of the through hole. According to the invention, the first cavity at least partially surrounding the central through hole is arranged in the rotor body, so that high-efficiency light weight and low rotation inertia are realized, and the driving load is obviously reduced; meanwhile, the closed cavity structure avoids deposition of particulate matters or by-products in the process gas, and the dynamic balance stability of the rotor during high-speed operation is effectively maintained.

Description

Technical Field

[0001] This invention relates to the field of vacuum generation technology, and more particularly to a rotor, forming method, and vacuum pump for a dry vacuum pump. Background Technology

[0002] In the field of vacuum acquisition technology, particularly in the design of vacuum pumps for high-precision process environments, rotor weight reduction has become a key factor in improving equipment performance. The traditional approach involves creating weight-reduction holes on the circumferential or end faces of the rotor body to reduce weight and rotational inertia. However, while this method can alleviate the problems caused by the rotor's own weight to some extent, its limitations and potential risks cannot be ignored.

[0003] Firstly, while some progress has been made in reducing rotor weight through the use of weight-reducing hole design, the overall weight reduction effect is limited and cannot fully meet the stringent requirements of modern high-efficiency vacuum pumps for weight and rotational inertia.

[0004] Secondly, with the increasing application of vacuum pumps in fields such as semiconductor, LCD panel, photovoltaic, and lithium battery manufacturing, especially in processes like chemical vapor deposition (CVD) and dry etching that require handling condensable gases or generating solid byproducts, the weight reduction hole design has revealed more serious problems. Because particulate matter, dust, and other byproducts generated during these processes easily deposit and adhere inside the weight reduction holes, over time, uneven deposits gradually disrupt the rotor's original precise dynamic balance. Once the dynamic balance is disrupted, the high-speed rotating rotor and its shaft system will experience significant vibration, leading to a shift in the center of rotation or rotational imbalance. This can cause abnormal friction and wear between rotors or between the rotor and the pump casing, resulting in excessive vibration and significantly increased noise during equipment operation; in extreme cases, it may even cause the vacuum pump to seize up. These problems seriously affect the continuity and stability of production and significantly shorten the actual service life of the equipment.

[0005] Therefore, there is an urgent need to design an improved rotor lightweight solution that can overcome the defects and shortcomings of existing technologies. Summary of the Invention

[0006] This invention provides a rotor, a forming method, and a vacuum pump for a dry vacuum pump, to solve technical problems such as the weak weight reduction effect of existing rotor weight reduction designs and the easy deposition of by-products in the weight reduction holes, which affects the dynamic balance of the rotor.

[0007] This invention provides a rotor for a dry vacuum pump, comprising: The body has a through hole formed at its rotation center; The protrusion is integrally formed with the body, and the protrusion is disposed on the outer periphery of the body and extends away from the through hole; The body has a first cavity inside, which is disposed around at least a portion of the circumferential region of the through hole.

[0008] According to the present invention, a rotor for a dry vacuum pump is provided. The protrusion has a second cavity inside, which is connected to the first cavity.

[0009] According to the present invention, a rotor for a dry vacuum pump is provided. The number of the first cavities is multiple, and the multiple first cavities are arranged at intervals along at least a portion of the circumferential region of the through hole.

[0010] A rotor for a dry vacuum pump according to the present invention further includes: Multiple reinforcing ribs are disposed inside the first cavity and / or the second cavity, and the reinforcing ribs are spaced apart circumferentially along the through hole.

[0011] According to the present invention, a rotor for a dry vacuum pump, The number of protrusions is one; The outer peripheral surface of the body on one side of the protrusion is an outwardly convex pitch circle surface, and the outer peripheral surface of the body on the other side of the protrusion is recessed, which is suitable for cooperating with the protrusion of another rotor.

[0012] According to the present invention, a rotor for a dry vacuum pump, The number of protrusions is multiple, and the multiple protrusions are evenly distributed along the circumference of the body; The outer peripheral surface of the body between adjacent protrusions is recessed.

[0013] The present invention also provides a method for forming the rotor of the above-mentioned dry vacuum pump, comprising the following steps: Rotors for dry vacuum pumps are prepared using sand casting or lost foam casting methods.

[0014] According to the forming method for the rotor of the dry vacuum pump provided by the present invention, the step of preparing the rotor for the dry vacuum pump using a sand casting method specifically includes: The casting process of the three-dimensional model of the rotor used in the dry vacuum pump was analyzed, and the metal outer mold and the core box for core making were machined. Prepare multiple core blocks and assemble them into a monolithic inner cavity sand core; Prepare upper and lower sand molds, place the integral inner cavity sand core into the lower sand mold, and after positioning, close and tighten the upper sand mold. The molten metal is poured into the mold cavity and opened after solidification. The rotor for the dry vacuum pump, after casting, undergoes post-processing. Perform precision machining and dynamic balancing of the rotor used in the dry vacuum pump.

[0015] According to the forming method for the rotor of a dry vacuum pump provided by the present invention, the step of preparing the rotor for the dry vacuum pump using a lost foam casting method specifically includes: A core is made according to the shape of the internal cavity of the rotor for the dry vacuum pump, and a foam pattern is prepared to enclose the core. A refractory coating layer is impregnated onto the surface of the foam pattern and then dried to form a shell. The foam pattern is placed in a sand box, filled with dry quartz sand, vacuumed to form a stable mold, and then molten metal is poured in. After the casting cools, the vacuum is released, the internal ceramic core is removed, and a rotor for the dry vacuum pump with uniform wall thickness is obtained. Perform precision machining and dynamic balancing of the rotor used in the dry vacuum pump.

[0016] The present invention also provides a vacuum pump, including the rotor for a dry vacuum pump described above, and further comprising: Two parallel rotating shafts are provided, and multiple sets of rotors for the dry vacuum pump are arranged axially at intervals on the rotating shafts. Each set of the dry vacuum pump has two rotors, and the two rotors are respectively mounted on two rotating shafts and cooperate with each other. Each group of rotors for dry vacuum pumps is of the same type, or includes at least two different types of rotors for dry vacuum pumps.

[0017] The above-mentioned one or more technical solutions provided by the present invention have at least the following beneficial technical effects: by setting a first cavity with uniform wall thickness inside the rotor body and at least partially surrounding the central through hole, high efficiency and lightweight and low rotational inertia are achieved, significantly reducing the drive load; at the same time, the closed cavity structure avoids the deposition of particulate matter or by-products in the process gas, effectively maintaining the dynamic balance stability of the rotor during high-speed operation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is one of the schematic diagrams of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 2 This is a second schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 3 This is the third schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 4 This is the fourth schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 5 This is the fifth schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 6 This is the sixth schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 7 This is the seventh schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 8 This is the eighth schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 9 This is the ninth schematic diagram of a rotor for a dry vacuum pump provided in an embodiment of the present invention; Figure 10 This is a partial structural schematic diagram of the vacuum pump provided in an embodiment of the present invention.

[0020] Figure label: 1. Body; 11. Through hole; 12. First cavity; 2. Protrusion; 21. Second cavity; 3. Reinforcing rib; 4. Rotating shaft. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] The following is combined with Figures 1-10 This invention describes a rotor, a molding method, and a vacuum pump for a dry vacuum pump, according to embodiments of the present invention.

[0023] like Figure 1-9As shown, an embodiment of the present invention provides a rotor for a dry vacuum pump, comprising: a body 1, wherein a through hole 11 is formed at the rotation center of the body 1; a protrusion 2, integrally disposed with the body 1, the protrusion 2 being disposed on the outer periphery of the body 1 and extending away from the through hole 11; wherein a first cavity 12 is formed inside the body 1, the first cavity 12 being disposed around at least a portion of the circumferential region of the through hole 11.

[0024] In some possible implementations, the rotor is an integral rotating structure, suitable for positive displacement vacuum equipment such as dry screw vacuum pumps, Roots pumps, or claw vacuum pumps. The body 1 is integrally molded from high-strength metal or high-performance engineering plastic to ensure structural integrity and dimensional stability. A through-hole 11 is formed axially through the rotation center of the body 1 for mounting with the drive shaft. The inner wall of this through-hole 11 can be provided with keyways, splines, or interference fit surfaces to achieve effective torque transmission. A protrusion 2 is provided on the outer periphery of the body 1. The protrusion 2 is an integral structure with the body 1, without welding or connection interfaces, thereby avoiding the risk of stress concentration or failure due to assembly errors or differences in thermal expansion. The protrusion 2 extends radially outward, and its contour is optimized according to the working chamber profile of the pump to achieve efficient gas transmission and sealing performance.

[0025] It should be understood that this embodiment achieves high efficiency, lightweight design, and low rotational inertia by providing a first cavity 12 with uniform wall thickness inside the rotor body 1 and at least partially surrounding the central through hole 11, significantly reducing the drive load. At the same time, this closed cavity structure avoids the deposition of particulate matter or by-products in the process gas, effectively maintaining the dynamic balance stability of the rotor during high-speed operation. It is particularly suitable for high-cleanliness vacuum process scenarios such as semiconductors and photovoltaics.

[0026] like Figure 2 , Figure 5 and Figure 8 As shown, according to an embodiment of the present invention, a rotor for a dry vacuum pump has a second cavity 21 formed inside the protrusion 2, and the second cavity 21 is connected to the first cavity 12.

[0027] It should be understood that the second cavity 21 is arranged along the extension direction of the protrusion 2 and is interconnected with the first cavity 12 inside the main body 1, forming an integral and continuous internal cavity system. The wall thickness of the second cavity 21 is uniform, and its wall thickness is equal to that of the first cavity 12, ensuring continuous and symmetrical material distribution throughout the rotor and effectively avoiding stress concentration or manufacturing deformation caused by sudden changes in local thickness. This design further reduces the overall weight of the rotor while maintaining the structural coordination and mechanical consistency between the protrusion 2 and the main body 1. Since both the first cavity 12 and the second cavity 21 are closed cavities and are not directly connected to the external process environment, even when handling process gases containing particulate matter or easily generating byproducts, it can prevent contaminants from depositing inside the weight-reducing structure and ensure dynamic balance stability under high-speed rotation.

[0028] Furthermore, the wall thickness of each first cavity 12 remains uniform, meaning the material thickness from the outer wall of the through hole 11 to the inner wall of each first cavity 12 is constant. More preferably, the wall thickness of each first cavity 12 is consistent and equal to the wall thickness of the second cavity 21 that may be disposed inside the protrusion 2. This uniform wall thickness design not only helps to maintain the structural rigidity and torsional resistance of key areas of the body 1 while reducing weight, but also significantly improves the controllability of forming processes such as casting, powder metallurgy, or additive manufacturing, and reduces defects such as shrinkage cavities, cracks, or residual stress caused by abrupt changes in wall thickness.

[0029] like Figure 3 , Figure 6 and Figure 9 As shown, according to an embodiment of the present invention, a rotor for a dry vacuum pump has a plurality of first chambers 12, which are arranged at least partially spaced along the circumferential direction of the through hole 11.

[0030] It should be understood that the multiple first cavities 12 are independent of each other or connected through microchannels, but the whole remains closed and does not penetrate the outer surface or end face of the body 1 or directly connect with the external process cavity. The cross-sectional shape of each first cavity 12 can be designed as circular, elliptical, racetrack-shaped or polygonal, etc., according to structural strength, manufacturing process and dynamic balance requirements, and its axial extension length can cover the entire length or part of the working section of the body 1.

[0031] like Figure 3 , Figure 6 and Figure 9 As shown, a rotor for a dry vacuum pump provided according to an embodiment of the present invention further includes: a plurality of reinforcing ribs 3 disposed inside the first cavity 12 and / or the second cavity 21, and the reinforcing ribs 3 are arranged at intervals along the circumferential direction of the through hole 11.

[0032] It should be understood that, depending on strength requirements or dynamic balance requirements, reinforcing ribs 3 can be provided inside the first cavity 12 and / or the second cavity 21. The reinforcing ribs 3 are spaced apart along the axial direction of the through-hole 11, thereby effectively suppressing the deformation and vibration of the thin-walled structure under high-speed rotation without significantly increasing mass. The cross-sectional shape of the reinforcing ribs 3 can be rectangular, trapezoidal, T-shaped, arc-shaped, or honeycomb-shaped, etc., and their thickness, height, and spacing are optimized according to the rotor's operating speed, material properties, and dynamic balance requirements. For example, under high-speed conditions, a smaller spacing and streamlined cross-section can be used to balance strength and aerodynamic / structural compatibility; in weight-sensitive applications, hollow or variable cross-section reinforcing ribs 3 can be used to further reduce weight. Preferably, all reinforcing ribs 3 are integrally formed with the inner wall of the first cavity 12 and / or the second cavity 21 to ensure structural continuity and avoid interface defects or stress concentration introduced during assembly.

[0033] It should be noted that although adding reinforcing rib 3 will slightly increase the local mass, the overall mass is still significantly lower than that of a solid structure because it is arranged inside the already formed weight-reducing cavity. Furthermore, by increasing the structural rigidity, a thinner cavity wall thickness design can be allowed. In addition, since reinforcing rib 3 is completely enclosed inside the first cavity 12 and does not come into contact with the external process environment, it will not become a deposition site for particulate matter or by-products, and therefore will not affect the cleanliness of the rotor or the long-term stability of its dynamic balance.

[0034] like Figure 1-3 As shown, according to an embodiment of the present invention, a rotor for a dry vacuum pump has one protrusion 2; wherein, the outer peripheral surface of the body 1 on one side of the protrusion 2 is an outwardly convex pitch circle surface, and the outer peripheral surface of the body 1 on the other side of the protrusion 2 is recessed, which is suitable for cooperating with the protrusion 2 of another rotor.

[0035] In some possible implementations, the rotor is a single-claw rotor structure suitable for dry claw vacuum pumps. There is one protrusion 2, which has a raised claw-like profile and is integrally formed with the rotor body 1. The body 1 is generally cylindrical or approximately elliptical in shape, and its outer circumferential surface is asymmetrically designed according to its meshing relationship with the paired rotor: specifically, the outer circumferential surface of the body 1 on one side of the protrusion 2 is an outwardly convex arc surface, which together with the protrusion 2 forms an active meshing profile; while the outer circumferential surface of the body 1 on the other side of the protrusion 2 is concave, forming a receiving space that matches the protrusion 2 of the paired rotor. The contour curve of this concave region (such as a cycloid, involute, conjugate arc, or optimized spline curve) is precisely designed to ensure that during the synchronous counter-rotation of the two rotors, the protrusion 2 of this rotor can smoothly embed into the concave region of the other rotor, achieving contactless or micro-gap meshing, thereby effectively sealing the working chamber and completing the stepwise compression and delivery of gas. Since the body 1 and the protrusion 2 are an integral structure without welding or fastening, the risk of connection failure caused by thermal expansion differences or high-frequency alternating loads is avoided, while ensuring high-precision dynamic balance performance.

[0036] It should be noted that, due to the geometric requirements for precise meshing with the mating rotor, the claw-shaped rotor has an asymmetrical structure on its outer circumferential surface: one side has an outwardly convex protrusion 2, while the other side forms an inwardly concave meshing groove. This structural characteristic determines that the material distribution inside the body 1 is uneven, and some areas (especially the concave side) have thinner walls or functional contour limitations. Therefore, the first cavity 12 cannot be continuously arranged along the entire circumference of the through hole 11. Accordingly, the first cavity 12 is rationally arranged in areas of the body 1 where the structure allows and the mechanical conditions are suitable, such as mainly located near the root of the protrusion 2 or in the thick-walled area corresponding to the outwardly convex arc surface, and extends at least partially along the circumference of the through hole 11 (e.g., covering a circumferential range of 90° to 270°). The shape, position, and extension angle of the first cavity 12 are optimized according to the local wall thickness, stress distribution, and dynamic balance requirements to ensure that while effectively reducing weight, the structural strength and meshing stability of the rotor at high speeds are not weakened.

[0037] like Figure 4-9 As shown, according to an embodiment of the present invention, a rotor for a dry vacuum pump has a plurality of protrusions 2, which are evenly distributed along the circumference of the body 1; wherein, the outer circumferential surface of the body 1 between adjacent protrusions 2 is recessed.

[0038] In some possible implementations, the rotor is a multi-lobed rotor structure suitable for Roots-type vacuum pumps. The number of lobes 2 is multiple (e.g., two, three, four, or more), evenly distributed circumferentially along the body 1, with equal included angles between adjacent lobes 2, forming a highly symmetrical rotating body configuration. This uniform distribution not only facilitates smooth gas delivery and compression within the working chamber but also significantly improves the rotor's dynamic balance performance under high-speed rotation, reducing vibration and noise. Furthermore, due to the structural symmetry resulting from the uniform distribution of lobes 2, this type of rotor is more likely to form a continuous or segmented weight-reducing cavity surrounding the through-hole 11 within the body 1 compared to claw-type rotors. Preferably, the first cavity 12 has a uniform wall thickness, and the material thickness remains consistent in the root region of the multiple lobes 2, thereby significantly reducing rotor mass and moment of inertia while maintaining sufficient bending and torsional stiffness.

[0039] The present invention also provides a method for forming the rotor of the dry vacuum pump described above, comprising the following steps: preparing the rotor of the dry vacuum pump using a sand casting method or a lost foam casting method.

[0040] It should be understood that the advantages of the above two forming methods are: they can form an integral rotor structure with a complex internal closed cavity in one step, avoiding interface defects caused by welding or assembly; sand casting is suitable for large-size, multi-variety production, while lost foam casting is particularly suitable for small and medium batch rotor manufacturing with complex internal cavities and high dimensional accuracy requirements; in addition, since the internal cavity is formed in the casting stage, there is no need for subsequent drilling or milling, which not only saves material and machining costs, but also fundamentally eliminates the risk of contamination deposition caused by surface weight reduction holes.

[0041] According to the above-described method for forming a rotor for a dry vacuum pump provided in the embodiments of the present invention, the steps of preparing the rotor using sand casting specifically include: analyzing the casting process of the three-dimensional model of the rotor and machining the metal outer mold and the core box for core making; preparing multiple core blocks and assembling them into an integral inner cavity sand core; preparing upper and lower sand molds, placing the integral inner cavity sand core into the lower sand mold, positioning it, closing the upper sand mold and tightening it; injecting molten metal liquid into the mold cavity, and opening the mold after solidification; performing post-processing on the cast rotor; and performing precision machining and dynamic balance adjustment on the rotor.

[0042] In one specific embodiment, the preparation of a rotor for a dry vacuum pump using a sand casting method includes the following steps: 1. Process Modeling and Core Box Fabrication: Based on the rotor's 3D CAD model, the casting process of the structure, including the outer contour and the internal conformal uniform thickness cavity, is analyzed, and dimensional compensation is performed according to the material shrinkage rate. Subsequently, the metal outer mold and the core box for core making are machined separately. The inner cavity sand core is designed to be formed by two or more core blocks along the symmetry plane or process reference plane to ensure that the complex curved surface can be demolded.

[0043] 2. Sand core preparation and assembly: Prepare sand core blocks, assemble the blocks in a special fixture and coat them with refractory adhesive to form an integral inner cavity sand core; for core segments with long cantilever, embed core skeletons to enhance rigidity, and pre-set metal core support mounting holes at key locations.

[0044] 3. Sand molding and mold assembly: Prepare upper and lower sand molds using a molding machine; after cleaning the cavity, place the entire inner cavity sand core into the lower sand mold, and use the core head and core seat to achieve precise positioning; insert the designed number of ductile iron core supports to prevent the sand core from drifting during the pouring process; close the sand mold and tighten it.

[0045] 4. Pouring and solidification control: A bottom-pouring open gating system is adopted to smoothly pour molten ductile iron melted to a specific temperature into the mold cavity at a certain filling speed; after being kept warm and slowly cooled in the sand mold to below 300℃, the mold is opened to reduce thermal stress.

[0046] 5. Post-treatment: Shot blasting is performed on the castings to remove surface sand; followed by stress-relieving annealing heat treatment. 6. Finishing and dynamic balancing: The rotor is finished by CNC machining center and the rotor is dynamically balanced.

[0047] It should be understood that due to the special structure of the rotor, sand casting also presents some technical challenges: the first cavity 12 and the second cavity 21 are closed, thin-walled structures that may have reinforcing ribs 3. The sand cores are slender, cantilevered, or multi-branched, making them prone to breakage, deformation, or displacement during handling, mold assembly, or pouring, leading to uneven wall thickness or even casting scrap. It is difficult to set effective venting channels in the closed cavity sand cores, preventing gas from escaping during molten metal filling and easily forming porosity. However, improving the permeability of the sand cores may sacrifice strength. The closed inner cavities have no openings, making it difficult to completely remove residual molding sand after casting, affecting dynamic balance and even clogging the cavities. Therefore, improvements can be made by using high-strength coated sand or cold-box resin sand for core making, combined with internal metal core reinforcement; designing micro-process holes in non-functional areas (which can be sealed later) to assist in venting and sand removal; optimizing the gating system, especially the setting of the risers and gating gates, to achieve stable filling and reduce the impact force of molten metal; and combining this with vibration-induced sand removal with high-pressure water jet / thermal shock sand removal processes.

[0048] According to the rotor forming method provided in the embodiments of the present invention, the steps of preparing the rotor using the lost foam casting method specifically include: making a core according to the shape of the internal cavity of the rotor, and preparing a foam pattern to wrap the core; impregnating the surface of the foam pattern with a refractory coating layer and drying it to form a shell; placing the foam pattern in a sand box, filling it with dry quartz sand, drawing a vacuum to form a stable mold, and pouring molten metal; after the casting cools, releasing the vacuum, removing the internal ceramic core, and obtaining a rotor with uniform wall thickness; and performing precision machining and dynamic balance adjustment of the rotor.

[0049] In one specific embodiment, the preparation of the rotor for the vacuum pump using the lost foam casting method includes the following steps: 1. Core and Pattern Preparation: A ceramic core is made according to the target cavity shape of the rotor and precisely fixed in the foaming mold; expandable polystyrene beads are injected and steam foaming is performed to form an overall foam pattern that encapsulates the core.

[0050] 2. Coating and drying: A uniform refractory coating layer is applied to the surface of the foam pattern, and then dried to form a sturdy and breathable shell.

[0051] 3. Molding and casting: Place the foam pattern in the sand box, fill it with dry quartz sand without binder, and after micro-vibration, vacuum is drawn to form a stable mold; pour molten metal under negative pressure, and the foam at the front of the molten metal vaporizes and fills the mold cavity.

[0052] 4. Sand removal and cleaning: After the casting cools, the vacuum is released and the dry sand flows out automatically; the internal ceramic core is removed by chemical dissolution or high-pressure water jet method to obtain a closed hollow rotor casting with uniform wall thickness; stress-relief annealing is then performed.

[0053] 5. Finishing and dynamic balancing: The rotor is finished by CNC machining center and the dynamic balancing is adjusted.

[0054] It should be understood that due to the special structure of the rotor, the lost foam casting method also presents some technical challenges: traditional adhesive foam patterns are difficult to accurately construct internally connected, uniformly thick closed cavities, especially multi-cavity or reinforced structures, which are prone to adhesive misalignment or wall thickness deviation; the risk of gasification product entrapment is high: complex internal cavities obstruct the path of foam pyrolysis gas, making it easy for it to be encapsulated by molten metal, forming carbon defects or pores; the large shrinkage rate of foam materials and the cumulative error of multi-segment bonding affect the consistency of cavity wall thickness. Based on this, improvements can be made by using CNC machining of integral EPS foam or 3D printing of foam patterns using soluble support materials to achieve high-precision one-piece molding; optimizing coating thickness and permeability, and using negative pressure control to promote gas discharge; and performing CT scanning or coordinate measuring machine inspection on key wall thickness areas to correct pattern dimensions in a closed loop.

[0055] In other feasible embodiments of the present invention, in order to realize the aforementioned hollow rotor structure with a cavity of uniform internal wall thickness, two process paths can also be adopted: split manufacturing-connection forming or additive manufacturing.

[0056] The first approach is the split-piece welding forming method: the rotor is divided into two semi-shell-like components along its axial or circumferential plane of symmetry. Each semi-shell is pre-formed with a portion of its outer contour and corresponding inner cavity surface through precision casting, forging, or machining. During assembly, the two semi-shells are precisely aligned, so that their respective inner cavity surfaces align to form a complete, closed first cavity 12 and / or second cavity 21. Subsequently, a high-precision welding process is used to seal the joint, ensuring a dense, porosity-free weld, and residual stress is eliminated through post-weld heat treatment. This method is suitable for high-strength alloy materials where complex internal cavities are difficult to achieve through integral casting, but strict control of welding deformation is required to ensure dynamic balance performance.

[0057] The second approach is metal additive manufacturing (i.e., metal 3D printing): Based on a complete three-dimensional digital model of the rotor, metal additive manufacturing technologies such as selective laser melting, electron beam melting, or directional energy deposition are used to melt and coat metal powder layer by layer, directly forming an integrated rotor structure including an external protrusion 2, a central through hole 11, and an internal closed cavity. This process does not require molds or sand cores and can freely construct complex internal cavity geometries that are difficult to achieve with traditional processes (such as annular cavities with uniform wall thickness, interconnected multi-cavities, and built-in reinforcing ribs). It also has high material utilization and near-net-shape forming accuracy. After printing, the rotor can be obtained by removing supports, hot isostatic pressing densification, stress relief annealing, and finishing key surfaces, thus achieving high cleanliness and high dynamic balance requirements.

[0058] Both methods described above can effectively achieve the hollow, lightweight rotor structure of this invention, avoiding the risk of contamination deposition caused by external weight-reduction holes. The split-piece welding method is suitable for manufacturing large-size rotors or rotors made of specific high-performance materials, while the metal 3D printing method has significant advantages in scenarios involving small batches, high complexity, and rapid iteration.

[0059] like Figure 10 As shown, this embodiment of the invention also provides a vacuum pump, including the rotor for a dry vacuum pump described above, and further including: two parallel rotating shafts 4, with multiple sets of rotors spaced axially on the rotating shafts 4; each set of rotors consists of two rotors, which are respectively mounted on the two rotating shafts 4 and cooperate with each other; wherein each set of rotors is of the same type, or includes at least two different types of rotors.

[0060] It should be understood that in practical applications of dry vacuum pumps, a multi-stage series rotor structure is often used to balance high pumping speed, low ultimate pressure, and a wide pressure adaptability range. Typical configurations include 3 to 7 stages of rotors, with each stage being the same or different types of positive displacement rotors.

[0061] In one specific embodiment, the first stage employs a two-lobe Roots rotor to achieve high-speed pre-pumping; the second to fourth stages employ hollow claw rotors, with their profile equations and axial thicknesses differentiated according to the compression ratio, gas temperature, and back pressure of their respective stages; the fifth stage employs a five-lobe Roots rotor to improve sealing and exhaust stability under high compression ratios. In this multi-stage architecture, although each rotor has a different function, they all adhere to the principle of conformal, uniform-thickness internal cavity design: that is, the internal cavity profile of each stage rotor maintains a constant distance from its outer working surface, thereby achieving lightweighting, reducing rotational inertia, and improving thermal expansion uniformity while satisfying their respective aerodynamic performance. It is worth noting that because each stage of the rotor bears different thermo-mechanical loads, its wall thickness, rib layout, and local material reinforcement strategies also need to be adjusted accordingly. However, the geometric characteristics of the internal cavity's "conformal, uniform-thickness" (the thickness of a certain structure or material layer remains constant, and its shape completely conforms to / follows the geometry of the substrate or target surface) remain consistent to ensure the dynamic balance consistency and structural reliability of the entire pump rotor assembly under high-speed operation.

[0062] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rotor for a dry vacuum pump, characterized in that Comprise: A body (1), the rotation center of the body (1) is formed with a through hole (11); A convex part (2) is integrally arranged with the body (1), the convex part (2) is arranged on the outer periphery of the body (1) and extends to the side away from the through hole (11); Wherein, the inside of the body (1) is formed with a first cavity (12), the first cavity (12) is arranged around at least part of the circumferential area of the through hole (11).

2. The rotor for dry vacuum pump according to claim 1, wherein, The inside of the convex part (2) is formed with a second cavity (21), and the second cavity (21) is arranged in communication with the first cavity (12).

3. The rotor for dry vacuum pump according to claim 1, wherein, The number of the first cavities (12) is multiple, and the multiple first cavities (12) are arranged at intervals along at least part of the circumferential area of the through hole (11).

4. The rotor for a dry vacuum pump according to claim 2, characterized in that, Further comprise: A plurality of reinforcing ribs (3) are arranged inside the first cavity (12) and / or the second cavity (21), and the reinforcing ribs (3) are arranged at intervals along the circumference of the through hole (11).

5. The rotor for dry vacuum pump according to claim 1 or 2, wherein, The number of the convex parts (2) is one; Wherein, the outer peripheral surface of the body (1) on one side of the convex part (2) is an outer convex pitch circle surface, and the outer peripheral surface of the body (1) on the other side of the convex part (2) is arranged concave, which is suitable for cooperating with the convex part (2) of another rotor for dry vacuum pump.

6. The rotor for dry vacuum pump according to claim 1 or 2, wherein, The number of the convex parts (2) is multiple, and the multiple convex parts (2) are uniformly distributed along the circumference of the body (1); Wherein, the outer peripheral surface of the body (1) between adjacent convex parts (2) is arranged concave.

7. A method of forming a rotor for a dry vacuum pump according to any one of the preceding claims 1 to 6, characterized in that Comprise the following steps: Preparation of the rotor for dry vacuum pump using sand casting method or lost foam casting method.

8. The forming method of a rotor for a dry vacuum pump according to claim 7, characterized in that, The step of preparing the rotor for dry vacuum pump using sand casting method specifically comprises: Casting process analysis is performed on the three-dimensional model of the rotor for dry vacuum pump, and a metal outer mold and a core box for preparing a core are processed; A plurality of core blocks are prepared and assembled into an integral internal cavity sand core; An upper sand mold and a lower sand mold are prepared, the integral internal cavity sand core is placed in the lower sand mold, and after positioning, the sand mold is closed and fastened; The molten metal liquid is poured into the cavity, and after solidification, the box is opened; The finished rotor for dry vacuum pump is post-processed; Finish machining and dynamic balance adjustment of the rotor for dry vacuum pump are performed.

9. The forming method of a rotor for a dry vacuum pump according to claim 7, characterized in that, The step of preparing the rotor for dry vacuum pump using lost foam casting method specifically comprises: A core is made according to the shape of the internal cavity of the rotor for dry vacuum pump, and a foam pattern wrapping the core is prepared; A refractory coating layer is coated on the surface of the foam pattern, and is dried to form a mold shell; The foam pattern is placed in a sand box, dry quartz sand is filled, vacuum is formed to form a stable mold, and metal liquid is poured; After the casting is cooled, the vacuum is released, the internal ceramic core is removed, and a rotor for a dry vacuum pump with uniform wall thickness is obtained; The rotor for a dry vacuum pump is subjected to finishing and dynamic balance adjustment.

10. A vacuum pump, characterized by The rotor for a dry vacuum pump of any one of claims 1-6, further comprising: Two parallel rotating shafts (4) are provided, and a plurality of groups of rotors for dry vacuum pumps are arranged axially between the rotating shafts (4); Each group of rotors for dry vacuum pumps is two, and the two rotors for dry vacuum pumps are arranged on the two rotating shafts (4) and cooperate with each other; Each group of rotors for dry vacuum pumps is of the same type, or at least includes two different types of rotors for dry vacuum pumps.

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