A method for milling a slot insert pocket on a stay bar of a turbine rotor wheel

Abstract

The application discloses a turbine rotor impeller upper supporting strip slot socket milling method in the technical field of rotor impeller machining, which comprises the following steps: S10, moving a T-shaped milling cutter to a milling position; S20, feeding the T-shaped milling cutter along the rotor impeller axis to perform axial linear milling operation; S30, returning the T-shaped milling cutter to a safe position; S40, rotating the T-shaped milling cutter by a preset angle; S50, feeding the T-shaped milling cutter along the rotor impeller axis to perform axial linear milling operation; repeating S30-S50 until the multiple axial linear milling of the T-shaped milling cutter fits a circumferential circular-arc-shaped supporting strip slot socket. The application adopts the axial linear milling operation mode of the T-shaped milling cutter on the supporting strip slot socket, controls the milling angle increment of the T-shaped milling cutter by mathematical analysis, and fits the multiple axial linear milling into the circular-arc-shaped supporting strip slot socket through fitting machining, so that the machining quality is ensured and the machining efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rotor impeller processing, and in particular to a method for milling a tightening strip groove socket on a steam turbine rotor impeller. Background Art

[0002] In steam turbine rotors, the use of tension bars for axially securing side-mounted blades is becoming increasingly common. These bars are T-shaped ring grooves located on both ends of the rotor impeller. Installing tension bars within these grooves restricts the axial movement of the side-mounted blades. To fit the tension bars into the T-shaped ring grooves, a tension bar slot with a similar shape must be machined into the grooves to facilitate insertion.

[0003] Large steam turbine rotors can be processed on wheel groove milling machines, but for small and medium-sized steam turbine rotors, due to the narrow axial spacing between two adjacent rotor impellers, it is impossible to use milling machines to process the tensioning strip slot sockets. They can only be rough-processed using T-type milling cutters on CNC boring machines. At the same time, in order to avoid overcutting the circumferential dimensions of the tensioning strip slot sockets, excessive residue will be caused and the fitter will need to grind them, resulting in a large workload and difficult quality control. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for milling the tightening strip slot socket on the turbine rotor impeller to solve the technical problems of large workload and difficult quality control in the existing tightening strip slot socket processing method.

[0005] The technical solution adopted by the present invention is: a method for milling a tightening groove socket on a steam turbine rotor impeller, comprising the following steps:

[0006] S10: moving the T-shaped milling cutter to a milling position opposite to the socket of the tensioning strip groove, and making the axis of the T-shaped milling cutter intersect perpendicularly with the axis of the rotor impeller;

[0007] S20: feeding the T-shaped milling cutter axially along the rotor impeller to perform axial linear milling on the flange of the T-shaped ring groove on the rotor impeller;

[0008] S30: After the milling is completed, the T-shaped milling cutter is retracted along the axial direction of the rotor impeller to a safe position;

[0009] S40: rotating the T-shaped milling cutter around the axis of the rotor impeller by a preset angle;

[0010] S50: feeding the T-shaped milling cutter axially along the rotor impeller to perform axial linear milling on the flange of the T-shaped ring groove on the rotor impeller;

[0011] Repeat S30 to S50 until the T-shaped milling cutter performs multiple axial linear milling operations to fit the circumferential arc-shaped tightening strip slot insertion.

[0012] Preferably, the angle between the axis of the T-shaped milling cutter and the midplane of the tightening strip slot is β, θ-α B ≦β≦θ-α A ;

[0013] Wherein, θ is the angle between the theoretical edge line of the tightening strip slot and the median plane of the tightening strip slot, α B is the angle between the actual milling edge line of the T-type milling cutter on the end face of the rotor impeller and the projection line of the axis of the T-type milling cutter on the end face of the rotor impeller, α A It is the angle between the actual milling edge line of the T-shaped milling cutter on the working surface of the T-shaped ring groove and the projection line of the axis of the T-shaped milling cutter on the working surface of the T-shaped ring groove.

[0014] Preferably, the

[0015]

[0016]

[0017] Among them, r is the milling radius of the T-type milling cutter; h is the distance that the outer circle of the T-type milling cutter exceeds the working surface of the T-type ring groove; H is the distance from the end face of the rotor impeller to the working surface of the T-type ring groove; R is the large arc radius of the tightening strip groove socket, and L is the chord length corresponding to the tightening strip groove socket.

[0018] Preferably, the T-shaped milling cutter is installed on a five-axis linkage machine tool, and the T-shaped milling cutter coincides with the main axis of the five-axis linkage machine tool.

[0019] Preferably, the preset angle of the T-type milling cutter is 0.5° to 1.5°.

[0020] Preferably, the preset angle of the T-type milling cutter is 1°.

[0021] Beneficial effects of the present invention:

[0022] The present invention adopts a T-type milling cutter to perform axial linear milling operations on the tightening strip slot socket, and uses mathematical analysis to control the milling angle increase of the T-type milling cutter, so that multiple axial linear millings are fitted into an arc-shaped tightening strip slot socket through fitting processing, which not only ensures the processing quality but also improves the processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the milling process of the tightening strip groove socket on the turbine rotor impeller of the present invention;

[0024] Figure 2 is the main view of the rotor impeller;

[0025] Figure 3 for Figure 2 AA view in;

[0026] Figure 4 for Figure 2 BB view in;

[0027] Figure 5 It is a partial three-dimensional schematic diagram of the rotor impeller;

[0028] Figure 6 Schematic diagram of the T-type milling cutter milling the outer contour of the T-shaped ring groove;

[0029] Figure 7 Main view of milling process for tightening strip slot.

[0030] Description of reference numerals in the figures:

[0031] 10. Rotor impeller;

[0032] 20. T-ring groove;

[0033] 21. Working surface;

[0034] 30. Tighten the slot socket;

[0035] 31. Milling arc surface;

[0036] 40. T-type milling cutter. DETAILED DESCRIPTION

[0037] The following is a further detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention.

[0038] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0041] Examples, such as Figure 1-Figure 7 As shown, a method for milling a tightening groove socket on a steam turbine rotor impeller includes the following steps:

[0042] S10 : moving the T-shaped milling cutter 40 along the radial direction of the rotor impeller 10 to a milling position opposite to the tensioning strip slot insertion opening 30 , and making the axis of the T-shaped milling cutter 40 perpendicularly intersect the axis of the rotor impeller 10 .

[0043] S20 : ​​The T-shaped milling cutter 40 is fed axially along the rotor impeller 10 to perform axial linear milling on the flange of the T-shaped ring groove 20 on the rotor impeller 10 .

[0044] S30: After the single axial linear milling is completed, the T-shaped milling cutter 40 is retracted along the axial direction of the rotor impeller 10 to a safe position.

[0045] S40: The T-shaped milling cutter 40 is rotated around the axis of the rotor impeller 10 by a preset angle, so that the T-shaped milling cutter 40 is rotated to the next milling position.

[0046] S50 : The T-shaped milling cutter 40 is fed axially along the rotor impeller 10 to perform axial linear milling on the flange of the T-shaped ring groove 20 on the rotor impeller 10 .

[0047] S30 to S50 are repeated until the T-shaped milling cutter 40 performs multiple axial linear milling operations to fit the circumferential arc-shaped tensioning strip slot insertion opening 30 .

[0048] The present application adopts a T-type milling cutter 40 to perform axial linear milling operations on the tensioning strip slot socket 30, and uses mathematical analysis to control the incremental milling angle of the T-type milling cutter 40, so that multiple axial linear millings can be fitted into an arc-shaped tensioning strip slot socket 30 through fitting processing, which can not only ensure the processing quality, but also improve the processing efficiency.

[0049] In a specific embodiment, if Figure 2-Figure 7As described above, during each axial linear milling operation performed by the T-shaped milling cutter 40, the axis of the T-shaped milling cutter 40 intersects perpendicularly with the axis of the rotor impeller 10, and the T-shaped milling cutter 40 moves axially along the rotor impeller 10 to perform axial milling operations on the tensioning strip slot socket 30 of the rotor impeller 10. The central angle corresponding to the tensioning strip slot socket 30 is 2θ, and the chord length is L, that is, the angle between the theoretical edge line of the tensioning strip slot socket 30 and the median plane of the tensioning strip slot socket 30 is θ; the angle between the actual milling edge line BB of the T-shaped milling cutter 40 on the end face of the rotor impeller 10 and the projection line of the axis OC of the T-shaped milling cutter 40 on the end face of the rotor impeller 10 is α B The angle between the actual milling edge line AA of the T-shaped milling cutter 40 and the projection line of the axis OC of the T-shaped milling cutter 40 on the working surface 21 of the T-shaped ring groove 20 is α A ;θ-α B ≦β≦θ-α A The milling arc surface 31 is formed between the actual milling edge line BB on the end surface of the rotor impeller 10 and the actual milling edge line AA on the working surface 21 of the T-shaped ring groove 20 .

[0050] Specifically, such as Figure 6 、 Figure 7 As shown, during each linear milling operation of the T-type milling cutter 40, the milling radius of the T-type milling cutter 40 is r, the distance that the outer circle of the T-type milling cutter 40 exceeds the working surface 21 of the T-type ring groove 20 is h, the distance from the end face of the rotor impeller 10 to the working surface 21 of the T-type ring groove 20 is H, the distance between the actual milling edge line BB of the T-type milling cutter 40 on the end face of the rotor impeller 10 and the projection line of the axis OC of the T-type milling cutter 40 on the end face of the rotor impeller 10 is BC; the distance between the actual milling edge line AA of the T-type milling cutter 40 on the working surface 21 of the T-type ring groove 20 and the projection line of the axis OC of the T-type milling cutter 40 on the working surface 21 of the T-type ring groove 20 is AC.

[0051] in,

[0052]

[0053] like Figure 6 、 Figure 7 As shown, OC is the axis of the T-type milling cutter 40, the AC straight line is the projection of the actual cutting part of the T-type milling cutter 40 on the working surface 21 of the T-shaped ring groove 20 on the end face of the rotor impeller 10, the BC straight line is the actual cutting part of the T-type milling cutter 40 on the end face of the rotor impeller 10, R is the large arc radius of the tightening groove socket 30, L is the width (chord length) that the tightening groove socket 30 must ensure, θ is half of the theoretical opening angle of the tightening groove socket 30, and α is the angle between the actual processing position of the tool and the axis of the T-type milling cutter 40.

[0054] in,

[0055]

[0056]

[0057] Through actual processing analysis, it is known that the theoretical edge of the tensioning strip slot socket 30 should be located between the actual milling edge BB on the end face of the rotor impeller 10 and the actual milling edge AA on the working surface 21 of the T-shaped ring groove 20. When the theoretical edge and the actual milling edge BB coincide, the actual angle between the axis OC of the T-shaped milling cutter 40 and the median plane of the tensioning strip slot socket 30 is: β min =θ-α B When the theoretical edge coincides with the actual milling edge AA, the actual angle between the axis OC of the T-type milling cutter 40 and the center plane of the tightening slot socket 30 is: β max =θ-α A At this time, the tensioning bar slot socket 30 does not need to be sharpened by a fitter to be installed in the tensioning bar.

[0058] In one embodiment, the T-shaped milling cutter 40 is mounted on a five-axis machine tool, with the T-shaped milling cutter 40 and the five-axis machine tool's main axis coinciding, i.e., OC represents the machine tool's main axis. With this arrangement, the T-shaped milling cutter 40 is mounted on the five-axis machine tool, with the axis of the T-shaped milling cutter 40 coinciding with the machine tool's main axis. The five-axis machine tool can then drive the T-shaped milling cutter 40 to rotate a predetermined angle about the axis of the rotor impeller 10, allowing the next axial linear milling operation to be performed.

[0059] Specifically, such as Figure 7 As shown, during the processing of the tensioning strip slot socket 30, the T-type milling cutter 40 is first positioned along the Z axis to the milling position opposite the tensioning strip slot socket 30, and then axially fed along the Y axis. After the processing is in place, it returns to a safe position. The five-axis linkage machine tool drives the T-type milling cutter 40 to rotate clockwise by a preset angle to perform the next axial linear milling operation, and fits the arc-shaped tensioning strip slot socket 30 through multiple axial linear milling operations, and the center angle of the tensioning strip slot socket 30 is equal to the theoretical center angle. Among them, the linear fitting accuracy is related to the preset angle of rotation of the T-type milling cutter 40. The smaller the preset angle, the more accurate the fitting, and the higher the processing quality of the tensioning strip slot socket 30.

[0060] Preferably, the preset angle of rotation of the T-shaped milling cutter 40 is 0.5° to 1.5°. This is because the smaller the preset angle of rotation of the T-shaped milling cutter 40, the higher the fitting accuracy of the arc-shaped tensioning strip slot 30. When the preset angle is greater than 1.5°, the fitting accuracy is low and cannot meet the required requirements. When the preset angle is less than 0.5°, although the fitting accuracy is high, the T-shaped milling cutter 40 will cause more axial linear milling operations, affecting processing efficiency.

[0061] More preferably, the preset angle of the T-shaped milling cutter 40 during rotation is 1°.

[0062] Compared with the prior art, this application has at least the following beneficial technical effects:

[0063] In this application, a five-axis linkage machine tool drives a T-type milling cutter 40 to perform axial milling operations on the rotor impeller 10, and the theoretical processing data obtained through mathematical model analysis controls the milling angle of the T-type milling cutter 40 to gradually increase, so that multiple axial straight line millings are performed to fit the arc-shaped tightening strip slot socket 30, which not only ensures the processing efficiency of the tightening strip slot socket 30 and reduces the cost, but also improves the processing quality of the tightening strip slot socket 30.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for milling the socket of the support strip groove on the turbine rotor impeller, characterized in that: The steps include: S10: moving the T-shaped milling cutter (40) to a milling position opposite to the support strip slot socket (30), and making the axis of the T-shaped milling cutter (40) intersect perpendicularly with the axis of the rotor impeller (10); S20: feeding the T-shaped milling cutter (40) axially along the rotor impeller (10) to perform axial linear milling on the flange of the T-shaped ring groove (20) on the rotor impeller (10); S30: After milling is completed, the T-shaped milling cutter (40) is retracted axially along the rotor impeller (10) to a safe position; S40: rotating the T-shaped milling cutter (40) around the axis of the rotor impeller (10) by a preset angle; S50: feeding the T-shaped milling cutter (40) axially along the rotor impeller (10) to perform axial linear milling on the flange of the T-shaped ring groove (20) on the rotor impeller (10); Repeating S30 to S50 until the T-shaped milling cutter (40) performs multiple axial linear milling operations to fit the circumferential arc-shaped tightening strip slot socket (30); The included angle between the axis of the T-shaped milling cutter (40) and the midplane of the tightening strip slot socket (30) is β, θ-α B ≦β≦θ-α A ; Wherein, θ is the angle between the theoretical edge line of the tightening strip slot socket (30) and the median plane of the tightening strip slot socket (30), α B is the angle between the actual milling edge line of the T-shaped milling cutter (40) on the end surface of the rotor impeller (10) and the projection line of the axis of the T-shaped milling cutter (40) on the end surface of the rotor impeller (10), α A The angle between the actual milling edge line of the T-shaped milling cutter (40) on the working surface (21) of the T-shaped ring groove (20) and the projection line of the axis of the T-shaped milling cutter (40) on the working surface (21) of the T-shaped ring groove (20); θ= ; α B = ； α A = ； Wherein, r is the milling radius of the T-shaped milling cutter (40); h is the distance between the outer circle of the T-shaped milling cutter (40) and the working surface (21) of the T-shaped ring groove (20); H is the distance between the end face of the rotor impeller (10) and the working surface (21) of the T-shaped ring groove (20); R is the large arc radius of the tightening strip slot socket (30), and L is the chord length corresponding to the tightening strip slot socket (30).

2. A method for milling a tightening groove socket on a steam turbine rotor impeller according to claim 1, characterized in that: The T-shaped milling cutter (40) is installed on a five-axis linkage machine tool, and the T-shaped milling cutter (40) coincides with a main axis of the five-axis linkage machine tool.

3. The method for milling the support groove socket of the turbine rotor impeller according to claim 1, characterized in that: The preset angle of the T-shaped milling cutter (40) is 0.5° to 1.5°.

4. A method for milling a tightening groove socket on a steam turbine rotor impeller according to claim 3, characterized in that: The preset angle of the T-shaped milling cutter (40) is 1°.

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