A machining method for preventing deformation of a split surface in an upper and lower split nozzle ring

Abstract

The present application relates to nozzle ring processing technical field, specifically disclose a kind of processing method for preventing deformation of middle split surface in upper and lower split type nozzle ring, comprising the following steps: determining the number of prepared nozzle blade is even or odd;When nozzle blade is even, even scribe method is used, when nozzle blade is odd, odd scribe method is used, after drawing middle split processing line in processing starting surface and scribing to each surface;The middle split surface processing line of upper and lower half nozzle ring is corrected respectively, then stress is removed by heat treatment;After heat treatment, nozzle ring is again line cutting along middle split surface, and all excess of nozzle ring two end faces is milled flat;Middle split surface is finely ground, and then connecting hole and positioning pin hole are drilled in middle split surface, the upper and lower half of nozzle ring is connected, and finally the production of finished product is completed by milling outer circle and inner hole as a whole.

Description

Technical Field

[0001] This invention relates to the field of nozzle ring processing technology, and in particular to a processing method for preventing deformation of the split surface of an upper and lower split nozzle ring. Background Technology

[0002] Currently, conventional nozzle rings for steam turbines and expanders consist of upper and lower halves, which are connected by connecting screws and locating pins. To prevent the working fluid from leaking from the inlet side of the nozzle ring through the split surface to the outlet side of the nozzle ring, thus affecting the efficiency within the stage, the free gap of the split surface of the finished nozzle ring is generally no more than 0.05 mm. When the upper and lower halves are freely fitted together, the gap between the mating surfaces is no more than 0.05 mm.

[0003] In the existing technology, the nozzle ring manufacturing process is generally as follows: the blade, outer ring body, and inner ring body are precision cast as a whole, heat treatment is performed to relieve stress, the cast nozzle ring is rough machined, heat treatment is performed again to relieve stress, the cast nozzle ring is aligned to the center, wire cut is performed to split it into two, connecting holes are drilled, positioning pins are installed, the upper and lower halves are assembled and precision machined, and the finished product is obtained.

[0004] However, in the existing technology, the heat treatment temperature control accuracy is high and the process is complex, making it difficult to guarantee the quality of stress relief. As a result, the finished parts often suffer from large deformation of the nozzle ring split surface after wire cutting, leading to unqualified free clearance of the split surface and low overall yield. Summary of the Invention

[0005] The purpose of this invention is to provide a processing method to prevent deformation of the split surface of an upper and lower split nozzle ring. This method aims to solve the technical problem in the prior art where the heat treatment temperature control accuracy is high and the process is complex, making it difficult to guarantee the quality of stress relief. As a result, the finished parts often experience large deformation of the split surface of the nozzle ring after wire cutting, leading to unqualified free clearance of the split surface and low overall yield.

[0006] To achieve the above objectives, the present invention employs a processing method for preventing deformation of the split surface of an upper and lower split nozzle ring, comprising the following steps: Determine whether the number of nozzle blades to be prepared is even or odd; When the number of nozzle blades is even, the even-number scribing method is used; when the number of nozzle blades is odd, the odd-number scribing method is used. After drawing the center machining line on the machining start surface, the scribing line is extended to each surface. Correct the machining lines of the split surfaces of the upper and lower nozzle rings respectively, wire cut the remaining material of the split surface, leave a machining allowance of 2~4mm on the split surface, mill the end face of the nozzle ring, leave a machining allowance of 0.5~1.0mm on both sides, and then perform heat treatment to relieve stress. After heat treatment, the nozzle ring is wire-cut again along the split surface, leaving a machining allowance of 0.1~0.5mm. All the allowance on both ends of the nozzle ring is then milled flat. After finely grinding the center parting surface and completely removing the machining allowance, connecting holes and positioning pin holes are drilled on the center parting surface to connect the upper and lower halves of the nozzle ring. Then, the outer circle and inner hole are milled as a whole to finally complete the finished product.

[0007] In the even-number scribing method, the nozzle ring circumference presents an arc state, and 1 to 2 more blades are cast in one direction, for a total of two pieces. One piece is used as the upper half blank and the other piece is used as the lower half blank. The outer circle of the blank is provided with a reference groove that is symmetrical about the center. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the edge of the blade are left with a machining allowance T2. The edge of the blade and the two end faces are left with machining allowances T1 and T3 respectively. The blade distribution angle is the same as the whole circle casting distribution. The distribution angle is equal to 360° divided by the total number of blades. Using the two symmetrical reference grooves as the machining starting surfaces, find the machining starting reference line. Using the spacing of 1 / 2 of the reference grooves as the reference starting value, draw the machining line of the split surface and extend the scribing line to each surface.

[0008] In the odd-number scribing method, the nozzle ring circumference presents a superior arc state, and 1-2 blades are cast in one direction, for a total of two pieces. One piece is used as the upper half blank, and the other piece is used as the lower half blank. The outer circle of the blank is provided with a reference groove that is symmetrical about the center of the upper half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the edge of the blade are left with a machining allowance of T2. The inner circle of the blank is provided with a reference groove that is symmetrical about the center of the lower half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the edge of the blade are left with a machining allowance of T2. The edge of the blade and the two end faces are left with machining allowances of T1 and T3 respectively. The blade distribution angle is the same as that of the whole circle casting distribution. A blank is used as the upper half of the nozzle ring. The machining starting surface of the two symmetrical reference grooves on the outer circle of the upper half of the nozzle ring is used as the machining reference line. Find the upper half machining starting reference line. With the spacing of 1 / 2 of the upper half reference groove as the reference starting value, draw the mid-section machining line and extend the line to each surface. The other piece serves as the lower half of the nozzle ring blank. The lower half of the nozzle ring is machined with the two symmetrical reference grooves on the inner circle as the machining reference lines. The machining start reference line of the lower half is found. The spacing of 1 / 2 of the lower half reference grooves is used as the reference start value. The machining line of the split surface is drawn and the line is extended to each surface.

[0009] The beneficial effects of the processing method for preventing deformation of the split surface of the upper and lower part of the nozzle ring of the present invention are as follows: by casting the upper and lower halves of the nozzle ring separately, the whole circle is cut off, and there will be no stress deformation on the split surface, which improves the finished product qualification rate and effectively ensures the gap value of the split surface. Compared with the traditional whole circle mold casting, the casting mold pin of the present invention is simple to operate, saves casting costs, and improves casting efficiency. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the nozzle ring precision casting body when the number of blades is even.

[0012] Figure 2 This is a schematic diagram of the first processing step of the nozzle ring when the number of blades is even.

[0013] Figure 3 This is a schematic diagram of the second processing of the nozzle ring when the number of blades is even.

[0014] Figure 4 This is a schematic diagram of the nozzle ring precision casting body when the number of blades is odd.

[0015] Figure 5 This is a schematic diagram of the first processing step of the nozzle ring when the number of blades is odd.

[0016] Figure 6 This is a schematic diagram of the second processing of the nozzle ring when the number of blades is odd. Detailed Implementation

[0017] Please see Figures 1 to 6 The present invention provides a processing method for preventing deformation of the split surface of an upper and lower split nozzle ring, comprising the following steps: Determine whether the number of nozzle blades to be prepared is even or odd; When the number of nozzle blades is even, the even-number scribing method is used; when the number of nozzle blades is odd, the odd-number scribing method is used. After drawing the center machining line on the machining start surface, the scribing line is extended to each surface. Correct the machining lines of the split surfaces of the upper and lower nozzle rings respectively, wire cut the excess material on the split surfaces, leaving a machining allowance of 2-4mm on the split surfaces, mill the end faces of the nozzle rings, leaving a machining allowance of 0.5-1.0mm on both sides, and then perform heat treatment to relieve stress. When the number of nozzle blades is even... Figure 2 As shown, when the number of nozzle blades is odd, as Figure 5 As shown; After heat treatment, the nozzle ring is wire-cut again along the split surface, leaving a machining allowance of 0.1~0.5mm. All remaining material on both ends of the nozzle ring is milled flat. (For nozzle blades with an even number...) Figure 3 As shown, when the number of nozzle blades is odd, as Figure 6 As shown; After finely grinding the center parting surface and completely removing the machining allowance, connecting holes and positioning pin holes are drilled on the center parting surface to connect the upper and lower halves of the nozzle ring. Then, the outer circle and inner hole are milled as a whole to finally complete the finished product.

[0018] Furthermore, in the even-number scribing method, the nozzle ring circumference presents an arc state, and 1 to 2 more blades are cast in one direction, for a total of two pieces. One piece is used as the upper half blank, and the other piece is used as the lower half blank. The outer circle of the blank has a reference groove that is symmetrical about the center. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the edge of the blade have a machining allowance of T2. The edge of the blade and the end face have machining allowances of T1 and T3. The blade distribution angle is the same as the whole circle casting distribution. The distribution angle is equal to 360° divided by the total number of blades. Using the two symmetrical reference grooves as the machining datum lines, find the machining start datum line. Using 1 / 2S as the datum starting value, draw the machining line for the split surface, and then extend the datum line to each surface. Figure 1 As shown.

[0019] Furthermore, in the odd-number scribing method, the nozzle ring circumference presents a superior arc state, and 1-2 additional blades are cast in one direction, for a total of two pieces. One piece serves as the upper half blank, and the other as the lower half blank. The outer circle of the blank has a reference groove that is symmetrical about the center of the upper half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face, and a machining allowance of T2 is left between the bottom of the reference groove and the edge of the blade. The inner circle of the blank has a reference groove that is symmetrical about the center of the lower half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face, and a machining allowance of T2 is left between the bottom of the reference groove and the edge of the blade. Machining allowances T1 and T3 are left between the edge of the blade and the end face. The blade distribution angle is the same as that of the whole circle casting. A blank is used as the upper half of the nozzle ring. The machining starting surface of the two symmetrical reference grooves on the outer circle of the upper half of the nozzle ring is used as the machining reference line. Find the machining starting reference line, and draw the machining line of the split surface with 1 / 2S value as the reference starting value. Then, extend the line to each surface. The other piece serves as the lower half of the nozzle ring blank. The lower half of the nozzle ring is machined using the two symmetrical reference grooves on the inner circle as the machining reference lines. The machining starting reference line is found, and with 1 / 2S1 as the reference starting value, the machining line of the split surface is drawn. This line is then extended to each surface, as shown below. Figure 4 As shown.

[0020] In this embodiment, the upper and lower halves of the nozzle ring are cast separately, avoiding the cutting of the entire circle. There is no stress deformation on the split surface, which improves the finished product qualification rate and effectively ensures the gap value of the split surface. Compared with the traditional whole circle mold casting, the casting mold pin of this invention is simple to operate, saves casting costs, and improves casting efficiency.

[0021] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A processing method for preventing deformation of the split surface of an upper and lower split nozzle ring, characterized in that, Includes the following steps: Determine whether the number of nozzle blades to be prepared is even or odd; When the number of nozzle blades is even, the even-number scribing method is used; when the number of nozzle blades is odd, the odd-number scribing method is used. After drawing the center machining line on the machining start surface, the scribing line is extended to each surface. Correct the machining lines of the split surfaces of the upper and lower nozzle rings respectively, wire cut the remaining material of the split surface, leave a machining allowance of 2~4mm on the split surface, mill the end face of the nozzle ring, leave a machining allowance of 0.5~1.0mm on both sides, and then perform heat treatment to relieve stress. After heat treatment, the nozzle ring is wire-cut again along the split surface, leaving a machining allowance of 0.1~0.5mm. All the allowance on both ends of the nozzle ring is then milled flat. After finely grinding the center parting surface and completely removing the machining allowance, connecting holes and positioning pin holes are drilled on the center parting surface to connect the upper and lower halves of the nozzle ring. Then, the outer circle and inner hole are milled as a whole to finally complete the finished product. In the even-number scribing method, the nozzle ring circumference presents an arc state, and 1 to 2 more blades are cast in one direction, for a total of two pieces. One piece is used as the upper half blank and the other piece is used as the lower half blank. The outer circle of the blank is provided with a reference groove that is symmetrical about the center. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the edge of the blade are left with a machining allowance T2. The edge of the blade and the two end faces are left with machining allowances T1 and T3 respectively. The blade distribution angle is the same as the whole circle casting distribution. The distribution angle is equal to 360° divided by the total number of blades. Using the machining starting surfaces of the two symmetrical reference grooves as machining reference lines, find the machining starting reference line, and use the spacing of 1 / 2 reference grooves as the reference starting value to draw the machining line of the split surface, and extend the scribing line to each surface; In the odd-number scribing method, the nozzle ring circumference presents a superior arc state, and 1 to 2 blades are cast in one direction, for a total of two pieces. One piece is used as the upper half blank, and the other piece is used as the lower half blank. The outer circle of the blank is provided with a reference groove that is symmetrical about the center of the upper half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the blade edge are left with a machining allowance T2. The inner circle of the blank is provided with a reference groove that is symmetrical about the center of the lower half of the nozzle ring. The inner end face of the reference groove is used as the machining starting face. The bottom of the reference groove and the blade edge are left with a machining allowance T2. The blade edge and the two end faces are left with machining allowances T1 and T3 respectively. The blade distribution angle is the same as the whole circle casting distribution. A blank is used as the upper half of the nozzle ring. The machining starting surface of the two symmetrical reference grooves on the outer circle of the upper half of the nozzle ring is used as the machining reference line. Find the upper half machining starting reference line. With the spacing of 1 / 2 of the upper half reference groove as the reference starting value, draw the mid-section machining line and extend the line to each surface. The other piece serves as the lower half of the nozzle ring blank. The lower half of the nozzle ring is machined with the two symmetrical reference grooves on the inner circle as the machining reference lines. The machining start reference line of the lower half is found. The spacing of 1 / 2 of the lower half reference grooves is used as the reference start value. The machining line of the split surface is drawn and the line is extended to each surface.

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