Method for centering of fir-tree wheel groove of steam turbine rotor

Abstract

A kind of secondary machine tool centering method of fir type wheel groove of steam turbine rotor, it is related to a kind of rotor centering method, to solve the problem that steam turbine rotor fir type wheel groove secondary machine tool machining cannot be centered.The present application installs shaft on machine tool spindle, moves shaft into wheel groove from wheel groove end face, makes the depth reference position line of shaft coincide with the depth size reference line position of wheel groove;When clearance value L1 is greater than L2, rotate rotor impeller counterclockwise;Conversely, rotate rotor impeller clockwise;If clearance value L1 is greater than L3, machine tool spindle is adjusted upwards along Y axis;Conversely, machine tool spindle is adjusted downwards along Y axis;When clearance value L1, clearance value L2, clearance value L3 and clearance value L4 are equal to theoretical value M;Shaft is taken off from machine tool spindle, wheel groove milling cutter for product machining is installed, product machining is carried out, and centering is completed.The beneficial effect is to realize the centering of rotor wheel groove secondary machine tool.

Description

Technical Field

[0001] This invention relates to a rotor centering method. Background Technology

[0002] The root grooves of the turbine rotor blades are generally machined using a forming groove milling cutter on a dedicated CNC groove milling machine. During groove machining, the grooves must be evenly distributed around the outer circumference of the impeller according to the design drawings, and the machining center of the grooves must pass through the rotor impeller center. Due to the rotor's own weight causing deflection, the rotor impeller center must be determined according to the impeller where each stage of grooves is located. Before machining the grooves, based on geometric principles: select a point on the outer circumference of the impeller; if two points of equal arc length relative to this point have the same height, it indicates that this point passes through the impeller center. This principle can be used to find the center position on the outer circumference of the impeller. However, if the machine tool malfunctions during the groove machining process, and some grooves are finished but others are not, requiring repair and a second machining of the rotor, the high point of the impeller's outer circumference center will have been removed. To ensure the correct position of the already machined grooves, the current method cannot find the rotor impeller center position, and it cannot guarantee that the machined groove center will pass through the rotor center. Therefore, this problem urgently needs to be solved. Summary of the Invention

[0003] The purpose of this invention is to solve the problem of failure to center the turbine rotor fir tree-shaped groove during secondary machining on a machine tool, and to propose a method for centering the turbine rotor fir tree-shaped groove during secondary machining on a machine tool.

[0004] The present invention discloses a method for secondary centering of the fir tree-shaped groove of a steam turbine rotor on a machine tool, which includes the following steps:

[0005] Step 1: Install the shaft onto the machine tool spindle, move the shaft into the wheel groove from the end face of the wheel groove, and adjust the depth position of the shaft so that the depth reference position line of the shaft coincides with the depth dimension reference line of the wheel groove.

[0006] Step 2: Measure the clearance value L1 between the upper taper measuring surface of the shaft and the first straight segment of the gear tooth surface, and measure the clearance value L2 between the upper taper measuring surface of the shaft and the second straight segment of the gear tooth surface. Compare the clearance values ​​L1 and L2. If the clearance value L1 is greater than the clearance value L2, rotate the rotor impeller counterclockwise and measure again until the clearance value L1 equals the clearance value L2. Conversely, if the clearance value L1 is less than the clearance value L2, rotate the rotor impeller clockwise and measure again until the clearance value L1 equals the clearance value L2.

[0007] Step 3: Measure the clearance value L3 between the lower taper measuring surface of the shaft and the third straight segment of the gear tooth surface. Compare the clearance values ​​L1 and L3. If the clearance value L1 is greater than the clearance value L3, adjust the machine tool spindle upward along the Y-axis until the clearance value L1 equals the clearance value L3; conversely, if the clearance value L1 is less than the clearance value L3, adjust the machine tool spindle downward along the Y-axis until the clearance value L1 equals the clearance value L3.

[0008] Step 4: Measure the dimensions of the gap values ​​L1, L2, L3, and L4 respectively. At this point, the gap values ​​L1, L2, L3, and L4 must be equal to the theoretical value M.

[0009] Step 5: Remove the shaft from the machine tool spindle, install the wheel groove milling cutter for product machining, perform product machining, and complete the centering.

[0010] Furthermore, the shaft has a central shaft tailstock;

[0011] The tailstock of the central shaft is the same as that of the wheel groove milling cutter.

[0012] Furthermore, the axis of symmetry of the wheel groove is the center line 1 of the wheel groove;

[0013] The angle between the center line of the wheel groove and the upper reference line of the wheel groove taper is angle A; the angle between the center line of the wheel groove and the lower reference line of the wheel groove taper is angle B.

[0014] The included angle A is equal to the included angle B;

[0015] The first straight segment and the second straight segment of the wheel groove tooth surface are parallel to the reference line on the center of the wheel groove taper, and the distance between the first straight segment of the wheel groove tooth surface and the reference line on the center of the wheel groove taper is the theoretical value M.

[0016] The third and fourth straight segments of the wheel groove tooth surface are parallel to the lower reference line of the wheel groove taper center, and the distance between the third straight segment of the wheel groove tooth surface and the lower reference line of the wheel groove taper center is the theoretical value M.

[0017] Furthermore, the front end of the shaft is conical; the central axis of the shaft is the center line of the shaft.

[0018] The angle between the centerline of the shaft and the upper taper measuring surface is angle C; the angle between the centerline of the shaft and the lower taper measuring surface is angle D.

[0019] The included angles D, C, B, and A have the same degree measure;

[0020] The length of the front end of the shaft is H3, where H3 = H1 - H2, and H1 is the depth of the groove, and H2 is the distance between the measuring tool and the bottom of the groove.

[0021] Furthermore, the theoretical value M is 0.5 mm, and the error of the theoretical value M is ±0.02 mm.

[0022] The beneficial effects of this invention are as follows: This invention solves the problem of centering the fir tree-shaped grooves of steam turbine rotors during secondary machining on a machine tool, and provides a method for centering the fir tree-shaped grooves of steam turbine rotors during secondary machining on a machine tool; the centering error is within ±0.02mm, which can meet the machining requirements of the design drawings; the invented process method is simple and easy to operate, and is an efficient and practical method for centering the fir tree-shaped grooves during secondary machining on a machine tool, which has been widely used in production practice. Attached Figure Description

[0023] Figure 1 This is a diagram showing the arrangement of the rotor fir tree-shaped grooves on the impeller in specific implementation method one;

[0024] Figure 2 This is a schematic diagram of the rotor fir tree-shaped wheel groove in specific implementation method one;

[0025] Figure 3 This is a structural schematic diagram of the shaft component in Specific Implementation Method 1;

[0026] Figure 4 This is a schematic diagram illustrating the principle of finding the center of the wheel groove in the first specific implementation method. Detailed Implementation

[0027] Specific Implementation Method 1: Combination Figures 1 to 4 This embodiment describes a method for secondary alignment of the fir tree-shaped wheel groove of a steam turbine rotor on a machine tool. The alignment method includes the following steps:

[0028] Step 1: Install the shaft 10 onto the machine tool spindle, move the shaft 10 into the wheel groove from the end face of the wheel groove, and adjust the depth position of the shaft 10 so that the depth reference position line 11 of the shaft 10 coincides with the depth dimension reference line 4 of the wheel groove.

[0029] Step 2: Measure the clearance value L1 between the upper taper measuring surface 12 of the shaft 10 and the first straight segment 5 of the gear tooth surface, and measure the clearance value L2 between the upper taper measuring surface 12 of the shaft 10 and the second straight segment 6 of the gear tooth surface. Compare the clearance values ​​L1 and L2. If the clearance value L1 is greater than the clearance value L2, rotate the rotor impeller counterclockwise and measure again until the clearance value L1 equals the clearance value L2. Conversely, if the clearance value L1 is less than the clearance value L2, rotate the rotor impeller clockwise and measure again until the clearance value L1 equals the clearance value L2.

[0030] Step 3: Measure the clearance value L3 between the lower taper measuring surface 13 of the shaft 10 and the third straight line segment 7 of the gear tooth surface. Compare the clearance values ​​L1 and L3. If the clearance value L1 is greater than the clearance value L3, adjust the machine tool spindle upward along the Y-axis until the clearance value L1 equals the clearance value L3; conversely, if the clearance value L1 is less than the clearance value L3, adjust the machine tool spindle downward along the Y-axis until the clearance value L1 equals the clearance value L3.

[0031] Step 4: Measure the dimensions of the gap values ​​L1, L2, L3, and L4 respectively. At this point, the gap values ​​L1, L2, L3, and L4 must be equal to the theoretical value M.

[0032] Step 5: Remove shaft 10 from the machine tool spindle, install the wheel groove milling cutter for product machining, perform product machining, and complete the centering.

[0033] In a preferred embodiment, the shaft 10 has a central shaft tailstock;

[0034] The tailstock of the central shaft is the same as that of the wheel groove milling cutter.

[0035] In a preferred embodiment, the axis of symmetry of the wheel groove is the center line 1 of the wheel groove;

[0036] The angle between the wheel groove centerline 1 and the upper reference line 2 of the wheel groove taper center is angle A; the angle between the wheel groove centerline 1 and the lower reference line 3 of the wheel groove taper center is angle B.

[0037] The included angle A is equal to the included angle B;

[0038] The first straight segment 5 and the second straight segment 6 of the wheel groove tooth surface are parallel to the reference line 2 on the center of the wheel groove taper, and the distance between the first straight segment 5 and the reference line 2 on the center of the wheel groove taper is the theoretical value M.

[0039] The third straight segment 7 and the fourth straight segment 8 of the wheel groove tooth surface are parallel to the lower reference line 3 of the wheel groove taper center, and the distance between the third straight segment 7 and the lower reference line 3 of the wheel groove taper center is the theoretical value M.

[0040] In a preferred embodiment, the front end of the shaft 10 is conical; the central axis of the shaft 10 is the shaft centerline 9;

[0041] The included angle between the center line 9 of the shaft and the upper taper measuring surface 12 is angle C; the included angle between the center line 9 of the shaft and the lower taper measuring surface 13 is angle D.

[0042] The included angles D, C, B, and A have the same degree measure;

[0043] The length of the front end of the shaft 10 is H3, where H3 = H1 - H2, and H1 is the depth of the groove, and H2 is the distance between the measuring tool and the bottom of the groove.

[0044] In a preferred embodiment, the theoretical value M is 0.5 mm, and the error of the theoretical value M is ±0.02 mm.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for secondary centering of the fir tree-shaped grooves of a steam turbine rotor on a machine tool, characterized in that, The method for finding the center includes the following steps: Step 1: Install the shaft (10) on the machine tool spindle, move the shaft (10) into the wheel groove from the end face of the wheel groove, and adjust the depth position of the shaft (10) so that the depth reference position line (11) of the shaft (10) coincides with the depth dimension reference line (4) of the wheel groove. Step 2: Measure the gap value L1 between the upper taper measuring surface (12) of the shaft (10) and the first straight segment (5) of the gear tooth surface, and measure the gap value L2 between the upper taper measuring surface (12) of the shaft (10) and the second straight segment (6) of the gear tooth surface; compare the gap value L1 and the gap value L2. When the gap value L1 is greater than the gap value L2, rotate the rotor impeller counterclockwise and measure again until the gap value L1 is equal to the gap value L2; conversely, if the gap value L1 is less than the gap value L2, rotate the rotor impeller clockwise and measure again until the gap value L1 is equal to the gap value L2. Step 3: Measure the clearance value L3 between the lower taper measuring surface (13) of the shaft (10) and the third straight line segment (7) of the gear tooth surface. Compare the size of the clearance value L1 and the clearance value L3. If the clearance value L1 is greater than the clearance value L3, adjust the machine tool spindle upward along the Y-axis until the clearance value L1 is equal to the clearance value L3. Conversely, if the clearance value L1 is less than the clearance value L3, adjust the machine tool spindle downward along the Y-axis until the clearance value L1 is equal to the clearance value L3. Step 4: Measure the dimensions of the gap values ​​L1, L2, L3, and L4 respectively. If the gap values ​​L1, L2, L3, and L4 are all equal to the theoretical value M, proceed to Step 5. Step 5: Remove the shaft (10) from the machine tool spindle, install the wheel groove milling cutter for product processing, perform product processing, and complete the centering.

2. The method for secondary centering of the fir tree-shaped wheel groove of a steam turbine rotor on a machine tool according to claim 1, characterized in that, The shaft (10) has a central shaft tail shank; The tailstock of the central shaft is the same as that of the wheel groove milling cutter.

3. The method for secondary centering of the fir tree-shaped wheel groove of a steam turbine rotor on a machine tool according to claim 1, characterized in that, The axis of symmetry of the wheel groove is the center line of the wheel groove (1); The angle between the center line (1) of the wheel groove and the upper reference line (2) of the wheel groove taper center is angle A; the angle between the center line (1) of the wheel groove and the lower reference line (3) of the wheel groove taper center is angle B. The included angle A is equal to the included angle B; The first straight segment (5) and the second straight segment (6) of the wheel groove tooth surface are parallel to the upper reference line (2) of the wheel groove taper center, and the distance between the first straight segment (5) of the wheel groove tooth surface and the upper reference line (2) of the wheel groove taper center is the theoretical value M, and the distance between the second straight segment (6) of the wheel groove tooth surface and the upper reference line (2) of the wheel groove taper center is the theoretical value M; The third straight segment (7) and the fourth straight segment (8) of the wheel groove tooth surface are parallel to the lower reference line (3) of the wheel groove taper center, and the distance between the third straight segment (7) of the wheel groove tooth surface and the lower reference line (3) of the wheel groove taper center is the theoretical value M, and the distance between the fourth straight segment (8) of the wheel groove tooth surface and the lower reference line (3) of the wheel groove taper center is the theoretical value M.

4. The method for secondary centering of the fir tree-shaped wheel groove of a steam turbine rotor on a machine tool according to claim 3, characterized in that, The front end of the shaft (10) is conical; the central axis of the shaft (10) is the shaft centerline (9); The included angle between the center line (9) of the shaft and the upper taper measuring surface (12) is angle C; the included angle between the center line (9) of the shaft and the lower taper measuring surface (13) is angle D; The included angles D, C, B, and A have the same degree measure; The length of the front end of the shaft (10) is H3, where H3 = H1 - H2, and H1 is the depth of the groove and H2 is the distance between the measuring tool and the bottom of the groove.

5. A method for secondary centering of the fir tree-shaped wheel groove of a steam turbine rotor on a machine tool according to claim 1 or 3, characterized in that, The theoretical value M is 0.5 mm, and the error of the theoretical value M is ±0.02 mm.

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