Blade top machining method of steam turbine rotor blade

Abstract

The invention provides a blade top processing method of a steam turbine rotor blade, which comprises the following steps of: S1, wrapping a plurality of stages of rotor blades on a rotor in a closed space enclosed by a molten wax pouring fence, and reserving a pouring port at the upper part of the molten wax pouring fence; s2, a molten wax solution is poured into the closed space through the pouring opening, so that a gap between every two adjacent rotor blades and a gap between the outer circumferential faces of the rotor blades and the molten wax pouring fence are filled with the molten wax solution; wherein the wax melting solution is a mixed solution of paraffin and rosin; s3, after the molten wax solution is solidified, the molten wax pouring fence is removed; and S4, the rotor is placed on a numerical control lathe to be turned. According to the blade top machining method of the steam turbine rotor blade, the blade top machining efficiency of the rotor blade can be greatly improved, and blade deformation is avoided; and vibration generated during machining is also avoided, and the machining stability and the machining quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical processing, and in particular to a method for processing the blade tip of a steam turbine rotor blade. Background Art

[0002] like Figure 1 As shown, the turbine rotor 100 is assembled from a rotor body 102 and multiple stages of rotor blades 101. Each stage of blades is independent of each other, that is, there is a set gap between two adjacent rotor blades (that is, the blade tips of each stage of rotor blades are free blade tips). Each stage of rotor blades has a machining allowance, and the blade tips of each stage of rotor blades 101 have a specific outer diameter φD and an angle α° with the horizontal direction (such as Figure 2 As shown in the figure, after the rotor blades are assembled, the blade tips of the multi-stage rotor blades need to be processed.

[0003] At present, there are two commonly used processing methods for the free blade tips of rotor blades. One is through grinding, that is, a grinding power head is installed on the grinding machine, and the blade tip is ground by grinding wheel profile grinding or profile grinding. This grinding method requires the configuration of a grinding power head, which is costly. Moreover, due to the different sizes of the blade tips at each level in the multi-stage blades, the space between the blades at each level is narrow, which is not conducive to avoidance. It is necessary to develop special grinding equipment and customize a variety of different grinding wheels, which is expensive and not conducive to single-piece small-batch processing. At the same time, the grinding wheel wears quickly, and the blade tip size and angle cannot be accurately controlled during grinding. The second is through turning, that is, the turning tool is used on a lathe to complete the pin turning of the blade top. Due to the insufficient rigidity of the blade, in order to prevent the blade from deforming during cutting, the tool path parameters during turning are not high, and the processing efficiency is low. In addition, since there is a set gap between two adjacent blades, during turning, the turning tool frequently switches between the blade top (cutting state) and the gap between the blade tops (non-cutting state), that is, intermittent cutting, which will cause large processing vibration, resulting in poor processing quality and low precision. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for machining the blade tip of a steam turbine rotor blade, so as to solve the problems existing in the prior art in machining the blade tip of a rotor blade.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a method for machining a blade tip of a steam turbine rotor blade, comprising the following steps:

[0006] S1. Wrap the multi-stage rotor blades on the rotor in a closed space surrounded by a molten wax casting enclosure, and a pouring port is left at the upper part of the molten wax casting enclosure;

[0007] S2, pouring a molten wax solution into the enclosed space through the pouring port, so that the molten wax solution fills the gap between two adjacent rotor blades and the gap between the outer peripheral surface of the rotor blade and the molten wax pouring enclosure; wherein the molten wax solution is a mixture of paraffin wax and rosin;

[0008] S3, after the molten wax solution solidifies, remove the molten wax pouring enclosure;

[0009] S4. Place the rotor on a CNC lathe for turning.

[0010] Preferably, the molten wax casting enclosure includes a first annular plate, a second annular plate and a middle enclosure, wherein the first annular plate and the second annular plate are respectively arranged at the left and right ends of the multi-stage rotor blades, and the middle enclosure is arranged around the circumferential direction of the multi-stage rotor blades, and one end of the middle enclosure is connected to the first annular plate, and the other end of the middle enclosure is connected to the second annular plate, so as to wrap the multi-stage rotor blades on the rotor in a closed space surrounded by the first annular plate, the second annular plate and the middle enclosure.

[0011] Preferably, the first annular plate and the second annular plate are both made of wood, and the middle enclosure is made of plastic.

[0012] Preferably, in step S1, "wrapping the multi-stage rotor blades on the rotor in a closed space surrounded by a molten wax casting enclosure" specifically includes: making the gap between the outer peripheral surface of the multi-stage rotor and the molten wax casting enclosure greater than 20 mm.

[0013] Preferably, the weight percentage of paraffin wax and rosin in the molten wax solution in step S2 is: when the room temperature is greater than or equal to 20°C, the weight percentage of paraffin wax and rosin is 2-2.5:1; when the room temperature is less than 20°C, the weight percentage of paraffin wax and rosin is 1-1.5:1.

[0014] Preferably, in step S3, "after the molten wax solution solidifies" specifically means: standing for 12 hours.

[0015] Preferably, in step S4, the rotation speed of the CNC lathe during turning is 20-25 r / min, the feed rate is 0.15-0.2 mm / r, and the single-side cutting depth is 0.4-0.8 mm.

[0016] Preferably, the method further comprises step S5: after the blade top of the rotor blade is processed, using a grooving tool to remove excess molten wax between two adjacent rotor blades.

[0017] Preferably, the method further comprises step S6: removing the rotor from the CNC lathe and washing the rotor with a high-pressure water gun.

[0018] As described above, the blade tip processing method of the steam turbine rotor blade of the present invention has the following beneficial effects: the blade tips of multiple rotor blades are wrapped together to form a whole by means of molten wax casting, so that sufficient rigidity can be obtained, the cutting parameters can be improved during turning, and blade deformation can also be avoided, thus greatly improving the processing efficiency compared with the prior art; and during turning, the turning tool is converted from intermittent cutting to continuous cutting, which also avoids processing vibration and improves processing stability and processing quality. At the same time, since the molten wax is non-toxic and harmless, the molten wax after turning can be processed together with the iron filings, and the residual molten wax can be reused after washing, which is harmless to the environment and the operator. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a schematic structural diagram of a steam turbine rotor in the prior art provided by the present invention.

[0020] Figure 2 Shown is a schematic diagram of the blade tip structure of a rotor blade in the prior art provided by the present invention.

[0021] Figure 3 Shown is a flow chart of the steps of the method for machining the tip of a steam turbine rotor blade provided by the present invention.

[0022] Figure 4 It is a schematic diagram showing the rotor provided by the present invention being subjected to molten wax casting.

[0023] Figure 5 It is a schematic diagram showing the rotor being turned after the molten wax provided by the present invention solidifies.

[0024] Figure 6 It is a schematic diagram showing the rotor provided by the present invention after processing.

[0025] Figure 7 It is a schematic diagram showing the rotor provided by the present invention after the excess molten wax is removed and rinsed.

[0026] Description of reference numerals:

[0027] 10. Wax casting enclosure

[0028] 11. First annular plate

[0029] 12. Second annular plate

[0030] 13 Middle hoarding

[0031] 20 melted wax solution

[0032] 201 Rubber hose

[0033] 100 Rotors

[0034] 101 Rotor Blades

[0035] 102 rotor body DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] The terms "first" and "second" and the like in the specification and drawings of this application are used to distinguish different objects, or to distinguish different processing of the same object, rather than to describe a specific order of objects.

[0038] In addition, the terms "including" and "having" and any variations thereof mentioned in the description of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include other steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices.

[0039] It should be mentioned before discussing exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe various operations (or steps) as sequential processes, many operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of various operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to methods, functions, procedures, subroutines, subprograms, etc. In addition, the embodiments in the present invention and the features in the embodiments can be combined with each other without conflict.

[0040] See also Figures 1 to 7 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0041] The present invention provides a method for machining a blade tip of a steam turbine rotor blade, such as Figure 3 As shown, the processing method comprises the following steps:

[0042] S1, wrapping the multi-stage rotor blades 101 on the rotor 100 in a closed space surrounded by a molten wax casting enclosure 10, and a casting port is left at the upper part of the molten wax casting enclosure 10;

[0043] Specifically, Figure 4 As shown, in this embodiment, the molten wax casting enclosure 10 includes a first annular plate 11, a second annular plate 12 and a middle enclosure 13, wherein the first annular plate 11 and the second annular plate 12 are respectively arranged at the left and right ends of the multi-stage rotor blades on the rotor 100, and the middle enclosure 13 is arranged around the circumferential direction of the multi-stage rotor blades, and one end of the middle enclosure 13 is connected to the first annular plate 11, and the other end of the middle enclosure 13 is connected to the second annular plate 12, so as to wrap the multi-stage rotor blades on the rotor 100 in a closed space surrounded by the first annular plate 11, the second annular plate 12 and the middle enclosure 13. Specifically, the pouring port is arranged on the circumferential surface of the middle enclosure 13. Of course, it should be noted that in other optional embodiments, those skilled in the art can also select any other structure to form the molten wax casting enclosure 10, as long as it can meet the requirements of enclosing the multi-stage rotor blades on the rotor 100 in a closed space.

[0044] Specifically, as a preferred embodiment, in this embodiment, the first annular plate 11 and the second annular plate 12 are made of wood, that is, the first annular plate 11 and the second annular plate 12 are both wooden boards, and the middle enclosure 13 is made of plastic. Through this design, the structure is simple and the cost is low. And by selecting the material of the middle enclosure 13 as plastic, the middle enclosure 13 can be specifically a rectangle. When the multi-stage rotor blade 101 is enclosed, the rectangular middle enclosure 13 is wound into a cylindrical tube along the circumferential direction of the multi-stage rotor blade 101, so as to achieve the circumferential surface of the multi-stage rotor blade 101, and then one end of the middle enclosure 13 is connected to the first annular plate 11, and the other end is connected to the second annular plate 12, so that the middle enclosure 13 and the first annular plate 11 and the second annular plate 12 form a closed space that wraps the multi-stage rotor blade.

[0045] Specifically, the pouring port may be a slit provided in the middle enclosure 13 along the axial direction of the rotor.

[0046] Furthermore, in order to ensure that the entire rotor can be wrapped by the molten wax, preferably, in this step S1, "the multi-stage rotor blades on the rotor are wrapped in a closed space surrounded by the molten wax casting enclosure", specifically, the gap between the outer peripheral surface of the multi-stage rotor and the molten wax casting enclosure must be greater than 20mm. Even if the diameters of the first annular plate 11 and the second annular plate 12 are greater than the maximum diameter of the rotor blades by 20mm. Through this design, Figure 4As shown, the rotor blade can be completely wrapped in the molten wax, so that the stability of turning can be improved.

[0047] S2, pouring a molten wax solution 20 into the enclosed space through the pouring port, so that the molten wax solution 20 fills the gap between two adjacent rotor blades and the gap between the outer peripheral surface of the rotor blade and the molten wax pouring enclosure; wherein the molten wax solution is a mixture of paraffin wax and rosin;

[0048] Specifically, in this step S2, the weight percentage of paraffin wax and rosin in the molten wax solution needs to be determined according to the room temperature during operation. Specifically, when the room temperature is greater than or equal to 20°C, the weight percentage of paraffin wax and rosin is 2 to 2.5:1, that is, the weight percentage of paraffin wax and rosin is controlled within the range of 2:1 to 2.5:1; when the room temperature is less than 20°C, the weight percentage of paraffin wax and rosin is 1 to 1.5:1. Specifically, it should be noted that the melting point of the above-mentioned paraffin wax is 50°C to 58°C, the melting point of rosin is 70°C to 80°C, and the above-mentioned paraffin wax is flaky paraffin wax.

[0049] Specifically, when pouring molten wax, Figure 4 As shown, paraffin wax and rosin need to be put into the wax melting furnace in advance to melt and mix the two, and then the wax melting solution, i.e., the mixture of paraffin wax and rosin, is injected into the closed space wrapped around the multi-stage rotor blades through the pouring port on the wax melting pouring enclosure 10 through the rubber tube 201 connected to the wax melting furnace. Specifically, in order to improve the pouring effect, the pouring temperature needs to be controlled during pouring, that is, when the weight percentage of paraffin wax and rosin is 2 to 2.5:1, it is better to start pouring when the temperature in the wax melting furnace is 80°C; when the weight percentage of paraffin wax and rosin is 1 to 1.5:1, it is better to start pouring when the temperature in the wax melting furnace is 65°C-70°C.

[0050] Furthermore, in order to improve the uniformity of pouring the molten wax solution, during pouring, the pouring can be performed separately at multiple positions including the front, middle and rear along the axial direction of the rotor 100, and intermittent pouring can be performed when pouring at one position, that is, pouring for a certain period of time and then pausing for a period of time (for example, 5 minutes) before continuing pouring, thereby further improving the uniformity of pouring.

[0051] S3, after the molten wax solution solidifies, remove the molten wax pouring enclosure;

[0052] Specifically, in step S3, "after the molten wax solution solidifies" specifically means: leaving the cast rotor to stand for 12 hours.

[0053] S4. Place the rotor on a CNC lathe for turning.

[0054] Specifically, in step S4, the turning parameters of the CNC lathe when turning the rotor 100 are: a rotation speed of 20 to 25 r / min, a feed rate of 0.15 to 0.2 mm / r, and a single-side cutting depth of 0.4 to 0.8 mm.

[0055] Specifically, in this step S4, if Figure 5 As shown, the turning tool used is a diamond turning tool with a main rake angle of 93 degrees and a tool tip radius of R1.2.

[0056] Furthermore, in order to improve the efficiency of removing excess molten wax, in this embodiment, step S5 is also included: after the blade tip of the rotor blade is processed (such as Figure 6 As shown), a slotting tool is used to remove the excess melted wax between two adjacent rotor blades (as shown Figure 7 As shown). This can reduce the workload of subsequent manual cleaning.

[0057] Furthermore, in order to thoroughly clean the melted wax on the rotor 100, preferably, in this embodiment, step S6 is further included: removing the rotor from the CNC lathe and washing the rotor with a high-pressure water gun to improve the cleanliness of the rotor to meet the requirements of the drawings.

[0058] The beneficial effects of the blade tip processing method of the steam turbine rotor blade of the present invention are: the blade tips of multiple rotor blades are wrapped together to form a whole by melt wax casting, so that sufficient rigidity can be obtained, and the cutting parameters can be improved during turning (the cutting parameters in the prior art without melt wax casting are: speed 12r / min, feed 0.08mm / r, single-sided cutting depth 0.15mm; the cutting parameters after melt wax casting in the present application are: speed 20-25r / min, feed 0.15-0.2mm / r, single-sided cutting depth 0.4-0.8mm.) and blade deformation can be avoided, so the processing efficiency is greatly improved compared with the prior art; and during turning, the turning tool is converted from intermittent cutting to continuous cutting, which also avoids processing vibration and improves processing stability and processing quality. At the same time, since the melt wax is non-toxic and harmless, the melt wax after turning can be processed together with iron filings, and the residual melt wax can be reused after rinsing, which is harmless to the environment and the operator.

[0059] Of course, it should be noted that the processing method of the present invention is not only applicable to the processing of the blade tips of steam turbine rotor blades, but can also be applied to the processing of parts similar to steam turbine rotor blades.

[0060] In summary, the blade tip processing method of the steam turbine rotor blade of the present invention uses the method of molten wax casting to form the free blade tip of the multi-stage blade into a whole, obtains sufficient rigidity, converts intermittent turning into continuous turning, and greatly improves the turning efficiency while meeting the processing size accuracy. The entire processing scheme (including casting, turning, cleaning, etc.) only takes 1 / 3 of the total time of intermittent cutting in the prior art. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0061] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for machining a blade tip of a steam turbine rotor blade, characterized in that: include: S1. Wrap the multi-stage rotor blades on the rotor in a closed space surrounded by a molten wax casting enclosure, and a pouring port is left at the upper part of the molten wax casting enclosure; S2, pouring a molten wax solution into the enclosed space through the pouring port, so that the molten wax solution fills the gap between two adjacent rotor blades and the gap between the outer peripheral surface of the rotor blade and the molten wax pouring enclosure; wherein the molten wax solution is a mixture of paraffin wax and rosin; S3, after the molten wax solution solidifies, remove the molten wax pouring enclosure; S4. Place the rotor on a CNC lathe for turning.

2. A method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: The molten wax casting enclosure includes a first annular plate, a second annular plate and a middle enclosure, wherein the first annular plate and the second annular plate are respectively arranged at the left and right ends of the multi-stage rotor blades, and the middle enclosure is arranged around the circumferential direction of the multi-stage rotor blades, and one end of the middle enclosure is connected to the first annular plate, and the other end of the middle enclosure is connected to the second annular plate, so as to wrap the multi-stage rotor blades on the rotor in a closed space surrounded by the first annular plate, the second annular plate and the middle enclosure.

3. The method for machining a blade tip of a steam turbine rotor blade according to claim 2, characterized in that: The first annular plate and the second annular plate are both made of wood, and the middle enclosure plate is made of plastic.

4. The method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: In the step S1, "wrapping the multi-stage rotor blades on the rotor in a closed space surrounded by a molten wax casting enclosure" specifically includes: making the gap between the outer peripheral surface of the multi-stage rotor and the molten wax casting enclosure greater than 20 mm.

5. The method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: The weight percentage of paraffin wax and rosin in the molten wax solution in step S2 is: when the room temperature is greater than or equal to 20°C, the weight percentage of paraffin wax and rosin is 2-2.5:1; when the room temperature is less than 20°C, the weight percentage of paraffin wax and rosin is 1-1.5:

1.

6. The method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: In the step S3, "after the molten wax solution solidifies" specifically means: standing for 12 hours.

7. The method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: In step S4, the rotation speed of the CNC lathe during turning is 20-25 r / min, the feed rate is 0.15-0.2 mm / r, and the single-side cutting depth is 0.4-0.8 mm.

8. The method for machining a blade tip of a steam turbine rotor blade according to claim 1, characterized in that: The method further comprises step S5: after the blade top of the rotor blade is processed, a grooving tool is used to remove excess molten wax between two adjacent rotor blades.

9. The method for machining a blade tip of a steam turbine rotor blade according to claim 8, characterized in that: The method further comprises step S6: removing the rotor from the CNC lathe and washing the rotor with a high-pressure water gun.

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