Auxiliary machining tool and method for rotor assembly of centrifugal compressor

Abstract

The invention relates to a machining tool and a machining method of a rotor assembly, in particular to an auxiliary machining tool and an auxiliary machining method of a centrifugal compressor rotor assembly, which are used for solving the problem that an existing rotor machining method depends on a center machining hole in the shaft end of a main shaft, so that the machining efficiency is high when the shaft end of the main shaft in the centrifugal compressor rotor assembly does not have the center machining hole. And high-precision machining of the rotor assembly of the centrifugal compressor is difficult to complete. The device comprises a fastening section, a positioning section and a connecting section which are coaxially and fixedly connected in sequence; external threads are arranged on the outer surface of the connecting section and used for being screwed into a connecting hole of a rotor assembly of the centrifugal compressor; the outer diameter of the positioning section is greater than that of the connecting section; a center hole extending in the axial direction of the central axis is formed in the end face of the fastening section and used for being matched with a tip of machining equipment when the fastening section is installed at the shaft end of a main shaft in the centrifugal compressor rotor assembly so as to assist in fixing and positioning of the centrifugal compressor rotor assembly on the machining equipment in the machining process.

Description

Technical Field

[0001] This invention relates to machining fixtures and machining methods for rotor assemblies, and more specifically to auxiliary machining fixtures and auxiliary machining methods for centrifugal compressor rotor assemblies. Background Technology

[0002] Centrifugal compressors are key power equipment in industrial production. Their rotor assembly, as the core rotating component, typically consists of a main shaft and multiple impeller stages. The first-stage impeller is often cantilevered at the end of the main shaft. To ensure the dynamic balance of the rotor assembly during high-speed operation, the entire rotor assembly must be precision-machined after all impellers are assembled. This ensures extremely high coaxiality in key dimensions such as the outer diameter of each impeller stage, the sealing grooves, and the support journals.

[0003] Currently, in the machining of shaft parts, it is common practice to set a central machining hole extending axially along the central axis on the end faces of the two shaft ends as a unified machining datum. For example, Chinese patent CN104476107B discloses a machining process for a turbine rotor, the core of which lies in repeatedly using the central machining holes at both ends of the turbine shaft for positioning, alignment, and finishing. By precisely grinding the central machining holes at both ends of the turbine shaft and always holding the central machining holes with double centers, the rotational accuracy of each level of outer circle and end face is ensured.

[0004] However, the above method is difficult to apply when the rotor assembly of a centrifugal compressor lacks a center-machined hole at one or both shaft ends due to the installation of the first-stage impeller or other structural components. If other parts are used as the machining reference, it is difficult to guarantee the coaxiality between the support journals on both sides of the rotor assembly and each stage of the impeller, failing to meet the coaxiality accuracy requirement of no more than 0.01 mm, which seriously affects the operating efficiency and reliability of the centrifugal compressor. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that existing rotor machining methods rely on a central machining hole on the spindle end, which makes it difficult to complete high-precision machining of centrifugal compressor rotor assemblies when there is no central machining hole on the spindle end of the spindle. The invention provides an auxiliary machining fixture and method for centrifugal compressor rotor assemblies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An auxiliary machining fixture for centrifugal compressor rotor assembly is provided for auxiliary machining of the centrifugal compressor rotor assembly. The centrifugal compressor rotor assembly includes a main shaft without a central machining hole at the shaft end and a multi-stage impeller mounted on the main shaft. The end face of the main shaft without a central machining hole is provided with positioning holes and connecting holes with internal threads that extend axially along the central axis and are arranged sequentially. Its special feature is that it includes a fastening section, a positioning section and a connecting section that are coaxially fixed together in sequence.

[0008] The connecting section is a cylindrical structure with external threads on its outer surface for screwing into the connecting hole;

[0009] The positioning section is a cylindrical structure with an outer diameter larger than that of the connecting section and is adapted to the positioning hole for abutting against the positioning hole.

[0010] The fastening section is a polygonal prism structure with a central hole extending axially along the central axis on its end face. It is used to cooperate with the center point of the processing equipment when installed on the main shaft end of the centrifugal compressor rotor assembly, so as to assist in the fixation and positioning of the centrifugal compressor rotor assembly on the processing equipment during the processing.

[0011] Furthermore, the connecting section includes a threaded section and a smooth section coaxially fixed to the threaded section; the surface of the threaded section is provided with external threads for screwing into the connecting hole;

[0012] The smooth section has a smooth surface and is coaxially fixed to the positioning section, and its outer diameter is smaller than that of the threaded section.

[0013] Furthermore, the outer diameter of the fastening section is smaller than the outer diameter of the positioning section;

[0014] The end face edge of the positioning segment that connects with the smooth segment is provided with a guide chamfer with a radius of 0.1 mm.

[0015] Furthermore, the central hole is a through hole that passes through the fastening section, the positioning section, and the connecting section.

[0016] Furthermore, the central hole located at the outer end of a section of the fastening segment is a tapered hole with a cone angle of 60°.

[0017] Furthermore, the fastening section, positioning section, and connecting section are all made of high-strength alloy steel, and their surfaces are heat-treated to improve wear resistance and rigidity.

[0018] Meanwhile, the present invention also provides an auxiliary processing method for a centrifugal compressor rotor assembly, which is characterized by including the following steps:

[0019] Step 1. Prepare auxiliary machining fixtures for the above-mentioned centrifugal compressor rotor assembly;

[0020] Step 2. Assemble the multi-stage impellers onto the main shaft to form the centrifugal compressor rotor assembly;

[0021] Step 3. Clamp the fastening section of the auxiliary machining fixture with a fastening tool, and screw the connecting section into the connecting hole of the main shaft until the positioning section is completely abutted in the positioning hole of the main shaft, thereby achieving radial positioning of the auxiliary machining fixture and the centrifugal compressor rotor assembly.

[0022] Step 4. Install the centrifugal compressor rotor assembly with auxiliary machining fixtures onto the machining equipment using the positioning reference;

[0023] The positioning reference is specifically:

[0024] If an auxiliary machining fixture is installed on one end of the main shaft in the centrifugal compressor rotor assembly, the positioning reference is formed by the center hole of the auxiliary machining fixture and the center machining hole of the other end of the main shaft in the centrifugal compressor rotor assembly.

[0025] If auxiliary machining fixtures are installed on both ends of the main shaft in the centrifugal compressor rotor assembly, the positioning reference is formed by the center holes of the two auxiliary machining fixtures.

[0026] Step 5. Use measuring instruments to align all the support journals of the main shaft in the centrifugal compressor rotor assembly installed on the processing equipment, so that the coaxiality error of the journals on both sides of the main shaft is no more than 0.01mm;

[0027] Step 6. After aligning the support journal of the main shaft, lock the machining equipment and perform turning and / or grinding on the outer diameter of the multi-stage impeller, the sealing groove, and the journal of the main shaft in the centrifugal compressor rotor assembly according to the process requirements to complete the auxiliary machining of the centrifugal compressor rotor assembly.

[0028] Furthermore, in step 3, the fastening tool is an open-end wrench, a box wrench, or a socket wrench, the opening size or inner hole shape of which is adapted to the outer contour of the polygonal prism of the fastening section.

[0029] Furthermore, in step 4, the processing equipment is a horizontal lathe or a grinding machine.

[0030] Furthermore, in step 5, the measuring instrument used is a dial indicator or a laser alignment instrument.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. This invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly. The fixture comprises a connecting section, a positioning section, and a fastening section with a central hole. This fixture enables the creation of a stable and reliable axial positioning reference at the end of the main shaft without a central machining hole, thus replacing the reliance on the central machining hole of the main shaft itself in traditional machining. This effectively solves the problem in the prior art where the lack of a central machining hole at the main shaft end prevents the use of double-center positioning for high-precision machining. It allows this type of main shaft to still undergo precision machining based on a unified reference after impeller assembly, ensuring the coaxiality of the outer diameter of each impeller stage, the sealing groove, and the main shaft support journal.

[0033] 2. This invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly. By setting a smooth section on the connecting section and placing this smooth section between the threaded section and the positioning section, an annular gap is formed between the smooth section and the inner wall of the connecting hole. This provides a temporary storage channel for small chips or cooling fluid that may be generated during machining, helping to prevent debris from accumulating on the threaded mating area, thereby protecting the thread accuracy. During thread machining, it can also serve as a relief groove, facilitating the machining of the threads on the surface of the connecting section.

[0034] 3. This invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly. The outer diameter of the fastening section is smaller than the outer diameter of the positioning section, ensuring that after installation, the outer contour of the fastening section will not interfere with the end face of the main shaft or surrounding structures. This facilitates the operation of fastening tools such as wrenches and ensures the stability and safety of the auxiliary machining fixture and the rotor assembly clamped on the machining equipment. Furthermore, by providing a guiding chamfer at the edge of the end face where the positioning section meets the smoothing section, alignment and insertion of the auxiliary machining fixture during screwing are facilitated, reducing bumps and friction during assembly and improving the smoothness and positioning reliability of the auxiliary machining fixture installation.

[0035] 4. This invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly. By setting the center hole as a through hole that runs through the entire auxiliary machining fixture, it not only facilitates center holding but also allows coolant or chip removal during machining. Simultaneously, it reduces the overall weight of the auxiliary machining fixture and facilitates machining and inspection during manufacturing. Furthermore, by using a 60° tapered center hole, which is the standard machine tool center angle, it can directly and perfectly mate with the centers of most general-purpose machine tools, improving the fixture's versatility and clamping repeatability, and ensuring the accurate transfer of positioning references.

[0036] 5. The present invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly. Each section of the auxiliary machining fixture is made of high-strength alloy steel, which ensures that the fixture has sufficient strength, rigidity and wear resistance when subjected to machining load and fastening torque. It can maintain accuracy for a long time, extend service life, and adapt to the harsh working conditions of precision machining of rotor assembly.

[0037] 6. This invention provides an auxiliary machining method for centrifugal compressor rotor assemblies. By first assembling the rotor assembly and then using auxiliary machining fixtures to establish and align the positioning reference, this method systematically solves the technological challenge of high-precision machining of rotor assemblies without a center machining hole at the shaft end. This method eliminates the reliance on the original center machining hole at the spindle end, utilizes auxiliary machining fixtures to reconstruct the reference, and ensures coaxiality ≤0.01mm through precise alignment, thereby achieving high-precision and repeatable machining of such rotor assemblies.

[0038] 7. This invention provides an auxiliary machining method for a centrifugal compressor rotor assembly. Alignment is achieved using a dial indicator or a laser alignment instrument. Both instruments possess high-precision measurement capabilities, accurately detecting and correcting minute deviations in the support journals on both sides of the main spindle. This is a key means to ensure stringent coaxiality requirements are met, thus improving the reliability and accuracy of the machining method. Simultaneously, a horizontal lathe or grinding machine is used as the machining equipment. Both are precision machine tools commonly used in this field, combining rigidity and precision, and are particularly suitable for turning and grinding shaft parts, ensuring the feasibility and process quality of this method in actual production. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of an embodiment of an auxiliary machining tooling for a centrifugal compressor rotor assembly according to the present invention;

[0040] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure;

[0041] Figure 3 This is a schematic diagram of an embodiment of an auxiliary machining tooling for a centrifugal compressor rotor assembly of the present invention, installed on the main shaft of a centrifugal compressor.

[0042] The attached figures are labeled as follows:

[0043] 1-Connecting section, 11-Smooth section, 12-Threaded section, 2-Positioning section, 3-Fastening section, 4-Center hole, 5-Main shaft, 51-Positioning hole, 52-Connecting hole. Detailed Implementation

[0044] To better understand the purpose, structure, and function of this invention, the auxiliary machining tooling and method for a centrifugal compressor rotor assembly of this invention will be described in further detail below with reference to the accompanying drawings.

[0045] This invention provides an auxiliary machining fixture for a centrifugal compressor rotor assembly, used for auxiliary machining of the centrifugal compressor rotor assembly. The centrifugal compressor rotor assembly includes a main shaft 5 without a central machining hole at its shaft end and a multi-stage impeller mounted on the main shaft 5. The shaft end face without a central machining hole has locating holes 51 extending axially along the central axis and arranged sequentially, and connecting holes 52 with internal threads. Figures 1-3 As shown, the auxiliary machining fixture includes: a connecting section 1, a positioning section 2, and a fastening section 3 that are coaxially and fixedly connected in sequence; the connecting section 1, the positioning section 2, and the fastening section 3 are all integrally formed from high-strength alloy steel, and their surfaces are heat-treated to improve wear resistance and rigidity.

[0046] The connecting section 1 is a cylindrical structure with external threads on its outer surface for screwing into the connecting hole 52. The positioning section 2 is a cylindrical structure with an outer diameter larger than that of the connecting section 1 and adapted to the positioning hole 51 for abutting within the positioning hole 51, thereby achieving radial positioning of the auxiliary machining fixture and the main shaft 5 in the centrifugal compressor rotor assembly. The connecting section 1 includes a threaded section 11 and a smooth section 12 coaxially fixed to the threaded section 11. The surface of the threaded section 12 is provided with external threads for screwing into the connecting hole 52. The surface of the smooth section 12 is smooth and coaxially fixed to the positioning section 2, with an outer diameter smaller than that of the threaded section 11. The end face edge of the positioning section 2 that connects with the smooth section 11 has a guide chamfer with a radius of 0.1 mm to facilitate the positioning of the main shaft 5 in the centrifugal compressor rotor assembly into the positioning hole 51.

[0047] The fastening section 3 is a polygonal prism structure with a central hole 4 extending axially along its end face. This hole 4 mates with the center point of the machining equipment when installed on the main shaft 5 of the centrifugal compressor rotor assembly, assisting in the fixation and positioning of the centrifugal compressor rotor assembly on the machining equipment during processing. The outer diameter of the fastening section 3 is smaller than the outer diameter of the positioning section 2. The polygonal prism structure can be pentagonal, hexagonal, or octagonal.

[0048] In this embodiment, the central hole 4 is a through hole that passes through the fastening section 3, the positioning section 2, and the connecting section 1. The central hole 4 is a tapered hole located at the outer end of the fastening section 3, with a tapered angle of 60°, which matches the tapered angle of the tip of the processing equipment.

[0049] An auxiliary machining method for a centrifugal compressor rotor assembly, based on the aforementioned auxiliary machining fixture for the centrifugal compressor rotor assembly, includes the following specific steps:

[0050] Step 1. Assemble the multi-stage impeller onto the main shaft 5 to form the centrifugal compressor rotor assembly.

[0051] Step 2. Clamp the fastening section 3 of the auxiliary machining fixture with a fastening tool, and screw the connecting section 1 into the connecting hole 52 of the main shaft 5 until the positioning section 2 is completely abutted in the positioning hole 51 of the main shaft 5, thereby achieving radial positioning of the auxiliary machining fixture and the centrifugal compressor rotor assembly. The fastening tool is an open-end wrench, box wrench, or socket wrench, and its opening size or inner hole shape is adapted to the polygonal prism outer contour of the fastening section 3. The outer cylindrical surface of the positioning section 2 and the stepped hole at the shaft end of the centrifugal compressor rotor assembly are in clearance fit or transition fit, with a fit clearance of 0.005mm to 0.025mm.

[0052] Step 3. Install the centrifugal compressor rotor assembly, equipped with auxiliary machining fixtures, onto the machining equipment using a positioning reference. The machining equipment is a horizontal lathe or grinding machine.

[0053] The positioning reference is specifically:

[0054] If an auxiliary machining fixture is installed on one end of the main shaft 5 in the centrifugal compressor rotor assembly, the positioning reference is formed by the center hole 4 of the auxiliary machining fixture and the center machining hole of the other end of the main shaft 5 in the centrifugal compressor rotor assembly.

[0055] If auxiliary machining fixtures are installed on both ends of the main shaft 5 in the centrifugal compressor rotor assembly, the positioning reference is formed by the center holes 4 of the two auxiliary machining fixtures.

[0056] Step 4. Use measuring instruments to align all the support journals of the main shaft 5 in the centrifugal compressor rotor assembly installed on the processing equipment, so that the coaxiality error of the journals on both sides of the main shaft 5 is no greater than 0.01mm; wherein, the measuring instruments used are dial indicators or laser alignment instruments.

[0057] Step 5. After aligning the support journal of the main shaft 5, lock the machining equipment and perform turning and / or grinding on the outer diameter of the multi-stage impeller, the sealing groove, and the journal of the main shaft 5 in the centrifugal compressor rotor assembly according to the process requirements to complete the auxiliary machining of the centrifugal compressor rotor assembly.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An auxiliary machining tool for a centrifugal compressor rotor assembly, used for auxiliary machining of a centrifugal compressor rotor assembly, the centrifugal compressor rotor assembly comprising a main shaft (5) with no center machining hole at a shaft end and a plurality of stages of impellers assembled on the main shaft (5); a positioning hole (51) and a connecting hole (52) with internal threads are arranged in sequence on the end face of the main shaft (5) with no center machining hole at the shaft end and extend axially along the central axis; characterized in that: It comprises a fastening segment (3), a positioning segment (2) and a connecting segment (1) which are coaxially fixed in sequence; The connecting segment (1) is a cylindrical structure, and an outer thread is arranged on the outer surface of the connecting segment (1) for being screwed into the connecting hole (52); The positioning segment (2) is a cylindrical structure, and the outer diameter of the positioning segment (2) is greater than the outer diameter of the connecting segment (1) and is matched with the positioning hole (51) for abutting in the positioning hole (51); The fastening segment (3) is a polygonal prism structure, and a center hole (4) extending along the central axis is arranged on the end face of the fastening segment (3) for cooperating with the center of the machining equipment when the fastening segment (3) is installed on the shaft end of the main shaft (5) of the centrifugal compressor rotor assembly, so as to assist the fixation and positioning of the centrifugal compressor rotor assembly on the machining equipment during the machining process.

2. The auxiliary machining tool for the centrifugal compressor rotor assembly according to claim 1, wherein: The connecting segment (1) comprises a threaded segment (11) and a smooth segment (12) which is coaxially fixed with the threaded segment (11); an outer thread is arranged on the surface of the threaded segment (12) for being screwed into the connecting hole (52); The surface of the smooth segment (12) is smooth, and the smooth segment (12) is coaxially fixed with the positioning segment (2), and the outer diameter of the smooth segment (12) is less than the outer diameter of the threaded segment (11).

3. The auxiliary machining tool for the centrifugal compressor rotor assembly according to claim 1 or 2, wherein: The outer diameter of the fastening segment (3) is less than the outer diameter of the positioning segment (2); A guide chamfer with a radius of 0.1 mm is arranged on the end face edge of the positioning segment (2) which is connected with the smooth segment (11).

4. The auxiliary machining tool for the centrifugal compressor rotor assembly according to claim 1, wherein: The center hole (4) is a through hole penetrating through the fastening segment (3), the positioning segment (2) and the connecting segment (1).

5. The auxiliary machining tool for the centrifugal compressor rotor assembly according to claim 1 or 4, wherein: The center hole (4) is a tapered hole at the outer end of the fastening segment (3), and the taper angle of the center hole (4) is 60°.

6. The auxiliary machining tool for the centrifugal compressor rotor assembly according to claim 1, wherein: The fastening segment (3), the positioning segment (2) and the connecting segment (1) are all made of high-strength alloy steel.

7. A method of secondary machining of a centrifugal compressor rotor assembly, characterized in that, The method comprises the following steps: Step 1. Preparing the auxiliary machining tool for the centrifugal compressor rotor assembly according to any one of claims 1-6; Step 2. Assembling the multi-stage impeller on the main shaft (5) to form the centrifugal compressor rotor assembly; Step 3. Clamping the fastening segment (3) of the auxiliary machining tool by a fastening tool, screwing the connecting segment (1) into the connecting hole (52) of the main shaft (5) until the positioning segment (2) completely abuts in the positioning hole (51) of the main shaft (5), and realizing the radial positioning of the auxiliary machining tool and the centrifugal compressor rotor assembly; Step 4. Installing the centrifugal compressor rotor assembly provided with the auxiliary machining tool on the machining equipment through the positioning reference; the positioning reference is specifically: If the auxiliary machining tool is installed on one end of the main shaft (5) in the centrifugal compressor rotor assembly, the positioning reference is formed by the center hole (4) of the auxiliary machining tool and the center machining hole of the other end of the main shaft (5) in the centrifugal compressor rotor assembly. If the auxiliary machining tool is installed on both ends of the main shaft (5) in the centrifugal compressor rotor assembly, the positioning reference is formed by the center holes (4) of the two auxiliary machining tools. Step 5. Use measuring instruments to align all the supporting journals of the main shaft (5) in the centrifugal compressor rotor assembly installed on the machining equipment, so that the coaxial error of the journals on both sides of the main shaft (5) is not greater than 0.01mm. Step 6. After completing the alignment of the supporting journals of the main shaft (5), lock the machining equipment, and perform turning and / or grinding machining on the outer circle of the multi-stage impeller, the sealing groove, and the journals of the main shaft (5) in the centrifugal compressor rotor assembly according to the process requirements, to complete the auxiliary machining of the centrifugal compressor rotor assembly.

8. The auxiliary machining method of the centrifugal compressor rotor assembly according to claim 7, characterized in that: In step 3, the tightening tool is an open-end wrench, a spanner wrench, or a socket wrench, and the opening size or inner hole shape thereof is adapted to the polygonal prism outer contour of the fastening segment (3).

9. The auxiliary machining method of the centrifugal compressor rotor assembly according to claim 7, characterized in that: In step 4, the machining equipment is a horizontal lathe or a grinding machine.

10. The auxiliary machining method of the centrifugal compressor rotor assembly according to any one of claims 7-9, characterized in that: In step 5, the measuring instrument used is a dial gauge or a laser alignment instrument.

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