A machining method for a high-pressure nozzle steam channel of a C-type steam turbine and a clamping device thereof

Abstract

The present application relates to the technical field of steam turbine production, in particular to a C-type steam turbine high-pressure nozzle steam channel processing method, comprising the following steps: S1, positioning the center of the nozzle ring, fixing two groups of cylinders on the angle iron through screws, and then placing the nozzle ring on the two groups of cylinders to limit the center of the nozzle ring; S2, fixing the position of the nozzle ring, clamping the nozzle ring at the front end of the angle iron through the two groups of clamps by screws, so as to stably fix the nozzle ring; S3, using a boring and milling machine to process the ball bottom hole, the ball bottom hole is difficult to process, and the boring and milling machine directly processes the front end of the nozzle ring through a numerical control program. Through the improvement of the clamping mode, the ball bottom hole is processed as a division reference, and then the pin hole is processed with the pin, so that the division is carried out, the positioning accuracy can reach about 0.05 mm, the part quality is greatly improved, the stability of the unit is improved, the processing time of 80 hours per piece is reduced to 48 hours per piece, and the efficiency is improved by 40%.

Description

A method for machining the steam passage of a high-pressure nozzle for a C-type steam turbine and its clamping device. Technical Field

[0001] This invention relates to the field of steam turbine manufacturing technology, and in particular to a method for machining the high-pressure nozzle steam passage of a C-type steam turbine and its clamping device. Background Technology

[0002] The nozzle ring is an important component of the steam turbine. Its function is to rectify the flow of boiler steam as it enters the turbine's flow path. The 36 15-degree steam passages on the nozzle ring are the core structure of this component, and their shape and position errors directly determine the thermal efficiency of the steam turbine.

[0003] The nozzle ring is machined as a whole circle. The method usually involves first scribing according to the position data on the drawing, marking the pitch circle line of the nozzle hole and the radial line passing through the center, and taking their intersection point. Then, the part is placed against the angle iron, the machine table is rotated 15 degrees, a machining block is placed on it, and machining is carried out. After machining each steam passage, the pressure plate is loosened once, and after rotating to the next intersection point, it is tightened and adjusted again before machining the next steam passage hole. Visually observing the drill tip to scribing is a complex operation. During the observation process, the rotation of the nozzle ring must also be controlled. The accuracy error is about 0.3. This error will affect the indexing accuracy of the nozzle, and the accumulation of scribing error will greatly reduce the accuracy.

[0004] The tapered hole requires high precision and needs to be finished with a tapered reamer. Therefore, it is necessary to first drill a stepped hole with a drill bit. The step variation of the hole should be controlled between 0.3mm and 0.5mm. Generally, 8-10 drill bits are needed for rough machining of the tapered hole to meet the tapered reaming requirements. Since the nozzle and the end face of the nozzle cone ring are at a 15-degree angle, the machine tool spindle diameter is limited. Only some slender drill bits and reamers can be selected to machine the nozzle. The workpiece diameter is about 800mm. Most companies do not have such a large horizontal indexing head, so it is necessary to use a 90-degree angle iron for clamping and machining. This makes the clamping and rough machining of the tapered hole complicated. In addition, it takes a lot of time to find and grind the drill bit used for rough machining before each operation. Workers need to frequently change drill bits and set tools for drilling, which is labor-intensive and results in a long processing time.

[0005] To address this, a method for machining the high-pressure nozzle steam passage of a C-type steam turbine and its clamping device are proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for machining the high-pressure nozzle steam passage of a C-type steam turbine and its clamping device, so as to solve the problems of low precision and low efficiency mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for machining a high-pressure nozzle steam passage for a C-type steam turbine and its clamping device, wherein the front end of the nozzle ring is provided with a nozzle steam passage including a spherical bottom hole and a conical hole, comprising the following steps: S1, positioning the center of the nozzle ring by fixing two sets of cylinders to an angle iron with screws, and then placing the nozzle ring on the two sets of cylinders, thereby defining the center of the nozzle ring; S2, fixing the position of the nozzle ring by clamping the nozzle ring to the front end of the angle iron with two sets of clamping plates using screws, thereby stably fixing the nozzle ring; S 3. Use a boring and milling machine to machine the ball bottom hole. The ball bottom hole is easy to machine and can be directly machined at the front end of the nozzle ring using a CNC program. S4. Make a pin hole according to the ball bottom hole. Use the ball bottom hole as the indexing reference and then machine the pin hole to match it for indexing. S5. Machine a tapered hole according to the pin hole. Rotate the screw rod to adjust the position of the machining auxiliary block inside the bridge-type pressure plate so that the machining auxiliary block is attached to the front end of the nozzle ring. Drill the hole by fixing the machining auxiliary block with a bridge-type pressure plate. Then, use a special drill bit to drill the machining auxiliary block to form a tapered hole.

[0008] A high-pressure nozzle steam passage clamping device for a C-type steam turbine includes a nozzle ring, a nozzle steam passage at the front end of the nozzle ring, the nozzle steam passage also includes a ball bottom hole and a conical hole, a pin hole at the rear end of the nozzle ring, the nozzle ring is set at the front end of an angle iron, a cylinder and a clamping plate are fixedly connected to both sides of the front end of the angle iron by screws, a bridge-type pressure plate is fixedly connected to the middle of the front end of the angle iron, and a processing auxiliary block is clamped at the rear end of the bridge-type pressure plate by a screw rod, and a hole is drilled on one side of the processing auxiliary block by a special drill bit.

[0009] Preferably, two sets of symmetrical triangular iron plates are provided at the rear end of the angle iron to enhance its supporting capacity.

[0010] Preferably, the two sets of cylinders are symmetrically arranged about the central axis of the angle iron, and the cylinders are arranged in a cylindrical shape.

[0011] Preferably, the inner spherical radius of the bottom hole is 11 mm, and the distance between the center of the inner spherical surface of the bottom hole and the front end face of the nozzle ring is 13.40 mm.

[0012] Preferably, the pin hole is circular and has a diameter of 22mm.

[0013] Preferably, the bridge-shaped pressure plate is located at the front end of the nozzle ring, and the bridge-shaped pressure plate is L-shaped.

[0014] Preferably, the processing auxiliary block is rectangular, and the rear end of the bridge-type pressure plate has a notch that matches the processing auxiliary block.

[0015] Preferably, the machining auxiliary block is used to assist in chip breaking that cannot be directly performed by the drill bit and reamer, facilitating the breaking of the tapered hole structure.

[0016] Preferably, the upper end of the special drill bit is provided with a drill head and a conical part, the diameter of the drill head is 7.10 mm, the slope of the conical part is 12 degrees, and the length of the conical part is 28.78 mm.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention improves the clamping method by first machining the ball bottom hole as the indexing reference, and then machining the pin hole to match it, thereby performing indexing. This can achieve a positioning accuracy of about 0.05mm, which greatly improves the quality of parts, improves the stability of the unit, and reduces the processing time per piece from 80 hours to 48 hours, increasing efficiency by 40%.

[0019] 2. This invention improves the drill bit by providing a specially designed drill bit with a drill head and a conical part at the upper end. The drill head has a diameter of 7.10 mm, the conical part has a slope of 12 degrees and a length of 28.78 mm, which is more suitable for machining conical holes. This replaces the method of using 8-10 drill bits for rough machining, reducing the workload of operators changing drill bits and frequently setting tools. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this 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 for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a schematic diagram of the overall process of a C-type steam turbine high-pressure nozzle steam passage machining method and its clamping device according to an embodiment of the present invention.

[0022] Figure 2 is an overall perspective view of a C-type steam turbine high-pressure nozzle steam passage processing method and its clamping device according to an embodiment of the present invention.

[0023] Figure 3 is a two-dimensional schematic diagram of a C-type steam turbine high-pressure nozzle steam passage processing method and its clamping device according to an embodiment of the present invention.

[0024] Figure 4 is an enlarged cross-sectional view of the nozzle steam passage of a C-type steam turbine high-pressure nozzle steam passage according to an embodiment of the present invention and its clamping device.

[0025] Figure 5 is an enlarged cross-sectional view of a specially made drill bit for processing a high-pressure nozzle steam passage of a C-type steam turbine and its clamping device according to an embodiment of the present invention.

[0026] The markings in the diagram are: 1. Nozzle ring; 2. Nozzle steam passage; 3. Ball bottom hole; 4. Tapered hole; 5. Pin hole; 6. Angle iron; 7. Cylinder; 8. Clamping plate; 9. Bridge-type pressure plate; 10. Machining auxiliary block; 11. Screw rod; 12. Special drill bit. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0028] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0029] Please refer to Figures 1 to 5. This invention provides a technical solution: a method for machining the steam passage of a high-pressure nozzle for a C-type steam turbine, comprising the following steps: S1, positioning the center of the nozzle ring by fixing two sets of cylinders to an angle iron with screws, and then placing the nozzle ring on the two sets of cylinders to define the center of the nozzle ring; S2, fixing the position of the nozzle ring by clamping the nozzle ring to the front end of the angle iron with two sets of clamping plates using screws, thereby stabilizing and fixing the nozzle ring; S3, machining the ball-bottom hole using a boring and milling machine. The ball-bottom hole is easy to machine and can be directly machined at the front end of the nozzle ring using a CNC program; S4, making a pin hole according to the ball-bottom hole, using the ball-bottom hole as the indexing reference, and then machining the pin hole to match it, thereby performing indexing; S5, machining a tapered hole according to the pin hole, adjusting the position of the machining auxiliary block inside the bridge-type pressure plate by rotating the screw rod, so that the machining auxiliary block is attached to the front end of the nozzle ring, drilling is performed by fixing the machining auxiliary block with a bridge-type pressure plate, and then a special drill bit is used to drill the machining auxiliary block to form a tapered hole.

[0030] A high-pressure nozzle steam passage clamping device for a C-type steam turbine includes a nozzle ring 1, a nozzle steam passage 2 at the front end of the nozzle ring 1, the nozzle steam passage 2 further including a ball bottom hole 3 and a conical hole 4, a pin hole 5 at the rear end of the nozzle ring 1, the nozzle ring 1 being positioned at the front end of an angle iron 6, a cylinder 7 and a clamping plate 8 being fixedly connected to both sides of the front end of the angle iron 6 by screws, a bridge-type pressure plate 9 being fixedly connected to the middle of the front end of the angle iron 6, and a machining auxiliary block 10 fixed by a screw rod 11 at the rear end of the bridge-type pressure plate 9. Holes are drilled on the side using a special drill bit 12; two sets of symmetrical triangular iron plates are set at the rear end of the angle iron 6 to strengthen the support capacity of the angle iron 6; two sets of cylinders 7 are symmetrically arranged about the central axis of the angle iron 6; the cylinders 7 are cylindrical; the clamping method is to fix the two cylinders 7 on the angle iron 6 to locate the center of the nozzle ring 1, and to process the pin hole 5 according to the center position of the nozzle ring 1; then, two clamping plates 8 are arranged in the horizontal direction to stably fix the nozzle ring 1, thereby increasing the stability and convenience of processing the nozzle ring 1.

[0031] As shown in Figures 2 and 4, the inner spherical radius of the ball bottom hole 3 is 11mm, and the distance between the center of the inner spherical surface of the ball bottom hole 3 and the front end face of the nozzle ring 1 is 13.40mm. The pin hole 5 is circular with a diameter of 22mm. The nozzle ring 1 is machined as a whole circle. The method is mostly to first scribing according to the position data of the drawing, mark the pitch circle line of the nozzle steam passage 2 and the radial line passing through the center, and take their intersection point. Then, the nozzle ring 1 is placed against the angle iron, the machine tool table is rotated 15 degrees, and a machining block is placed on it before machining. Visually observing the drill tip for scribing is a complex operation. During the observation process, the rotation of the nozzle ring must also be controlled. The accuracy error is about 0.3, which will affect the indexing accuracy of the nozzle. In addition, the accumulation of scribing error will greatly reduce the accuracy. Furthermore, since the nozzle and the end face of the nozzle cone ring are at a 15-degree angle, the machine tool spindle... Due to diameter limitations, only slender drill bits and reamers can be used to process the nozzle. The workpiece diameter is around 800mm. Most companies don't have such a large horizontal indexing head, so a 90-degree angle iron must be used for clamping. This makes the clamping and roughing of the tapered hole complex. Now, we first process the nozzle passage 2 on the reverse side of the passage. Then, using the ball bottom hole 3 as the indexing reference, we process the pin hole 5 and its pin to perform indexing. The ball bottom hole 3 is easy to process and can be directly processed on the end face using a CNC program on a boring and milling machine. Through the improvement of the clamping method, the positioning accuracy can be achieved to about 0.05mm, which greatly improves the quality of the parts and the stability of the unit. The processing time per piece has been reduced from 80 hours to 48 hours, and the efficiency has increased by 40%. Calculated at 300 yuan / hour, the cost can be saved by 9600 yuan per piece.

[0032] As shown in Figures 3 and 5, the bridge-type pressure plate 9 is set at the front end of the nozzle ring 1. The bridge-type pressure plate 9 is L-shaped, and the machining auxiliary block 10 is rectangular. The rear end of the bridge-type pressure plate 9 has a notch that matches the machining auxiliary block 10. The machining auxiliary block 10 is used to assist in chip breaking that cannot be directly performed by the drill bit and reamer, facilitating the breaking of the structure of the conical hole 4. The upper end of the special drill bit 12 is provided with a drill head and a conical part. The diameter of the drill head is 7.10 mm, the slope of the conical part is 12 degrees, and the length of the conical part is 28.78 mm. The conical hole 4 has high precision requirements and needs to be finished with a conical reamer. Therefore, a stepped hole needs to be drilled first. The step change of the hole is controlled between 0.3 mm and 0.5 mm. Generally, 8-10 drill bits are needed for rough machining of the conical hole to meet the conditions for conical reaming. Since the nozzle steam passage 2 is at a 15-degree angle to the end face of the nozzle ring 1, the diameter of the machine tool spindle is limited, and only one can be selected. For machining nozzles using slender drill bits and reamers, with workpiece diameters around 800mm, most companies lack horizontal indexing heads of this size, requiring 90-degree clamping. This complicates the clamping and taper hole 4 machining processes, and the roughing drill bits require significant time to find and re-sharpen before each operation. Workers frequently need to change drill bits and perform tool setting, resulting in high labor intensity and long machining times. The machining auxiliary block 10 assists the drill bits and reamers in chip-breaking drilling. It is essential for machining the taper hole structure because the specially designed drill bit 12 has a drill head and a conical section at its upper end. The drill head has a diameter of 7.10mm, the conical section has a slope of 12 degrees, and a length of 28.78mm. This improved drill bit is more suitable for machining the taper hole 4, replacing the need for 8-10 drill bits for roughing and reducing the workload of changing drill bits and frequent tool setting for operators.

[0033] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0034] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for machining the high-pressure nozzle steam passage of a C-type steam turbine, characterized in that, The process includes the following steps: S1. Locate the center of the nozzle ring by fixing two sets of cylinders to the angle iron with screws, and then placing the nozzle ring on the two sets of cylinders to define the center of the nozzle ring; S2. Fix the position of the nozzle ring by clamping the nozzle ring to the front end of the angle iron with two sets of clamping plates using screws, thus stabilizing the nozzle ring; S3. Machining the ball-shaped bottom hole using a boring and milling machine. Machining the ball-shaped bottom hole is relatively easy; it can be directly machined on the front end of the nozzle ring using a CNC program; S4. Create a pin hole based on the ball-shaped bottom hole, using the ball-shaped bottom hole as the indexing datum. The pin hole is then machined to match the pin, thus indexing is performed; S5, a tapered hole is machined according to the pin hole, the position of the machining auxiliary block inside the bridge-type pressure plate is adjusted by rotating the screw rod, so that the machining auxiliary block is attached to the front end of the nozzle ring, and the machining is machined by fixing the machining auxiliary block with a bridge-type pressure plate, and then a special drill bit is used to drill the machining auxiliary block to form a tapered hole; the front end of the nozzle ring (1) is provided with a nozzle steam passage (2), the nozzle steam passage (2) also includes a ball bottom hole (3) and a tapered hole (4), and the rear end of the nozzle ring (1) is provided with a pin hole (5). The nozzle ring (1) is located at the front end of the angle iron (6). Both sides of the front end of the angle iron (6) are fixedly connected to a cylinder (7) and a clamping plate (8) by screws. A bridge-shaped pressure plate (9) is fixedly connected to the middle of the front end of the angle iron (6). A processing auxiliary block (10) is fixed to the rear end of the bridge-shaped pressure plate (9) by a screw rod (11). One side of the processing auxiliary block (10) is drilled using a special drill bit (12). The bridge-shaped pressure plate (9) is located at the front end of the nozzle ring (1). The processing auxiliary block (10) is arranged in an L-shape; the processing auxiliary block (10) is arranged in a rectangle, and the rear end of the bridge-type pressure plate (9) is provided with a notch that matches the processing auxiliary block (10); the processing auxiliary block (10) is used to assist the drill bit and reamer in chip breaking, which is not possible to be done directly, and facilitates the hole breaking processing of the structure of the conical hole (4); the upper end of the special drill bit (12) is provided with a drill head and a conical part, the diameter of the drill head is 7.10mm, the slope of the conical part is 12 degrees, and the length of the conical part is 28.78mm.

2. The method for machining the high-pressure nozzle steam passage of a C-type steam turbine according to claim 1, characterized in that, Two sets of symmetrical triangular iron plates are provided at the rear end of the angle iron (6) to enhance the supporting capacity of the angle iron (6).

3. The method for machining the high-pressure nozzle steam passage of a C-type steam turbine according to claim 1, characterized in that, The two sets of cylinders (7) are symmetrically arranged about the central axis of the angle iron (6), and the cylinders (7) are cylindrical.

4. The method for machining the high-pressure nozzle steam passage of a C-type steam turbine according to claim 1, characterized in that, The inner spherical radius of the ball bottom hole (3) is 11 mm, and the distance between the center of the inner spherical surface of the ball bottom hole (3) and the front end face of the nozzle ring (1) is 13.40 mm.

5. The method for machining the high-pressure nozzle steam passage of a C-type steam turbine according to claim 1, characterized in that, The pin hole (5) is circular and has a diameter of 22 mm.

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