A numerical control forming machining method for large water bucket parts of an impulse water turbine

Abstract

The application provides a large water bucket part numerical control forming machining method for an impulse water turbine, and belongs to the technical field of machining, and solves the technical problem of high machining difficulty of the existing large water bucket forging of the impulse water turbine. The large water bucket part numerical control forming machining method for the impulse water turbine comprises the following steps: S1, welding a clamping block on the water bucket forging according to the centroid position of the water bucket forging, and clamping the water bucket forging on a floor type boring machine according to a front face station; S2, machining an auxiliary machining process groove; S3, sequentially machining a first machining area, a second machining area and a third machining area; S4, clamping the water bucket forging on the floor type boring machine according to a back face station; S5, machining a fourth machining area; S6, machining a fifth machining area; S7, machining a sixth machining area; and S8, machining a seventh machining area, and finally obtaining the water bucket part. The application provides a good machining method for large water bucket numerical control machining forming.

Description

Technical Field

[0001] This invention belongs to the field of mechanical processing technology, specifically relating to a CNC forming method for large water bucket parts used in impact turbines. Background Technology

[0002] China's unique three-tiered, terraced topography, sloping from west to east, has spurred the development of numerous impulse turbine hydroelectric power stations. These are almost entirely concentrated in the high mountain valleys of southwestern plateau regions such as Sichuan and Yunnan, where the rivers have significant head differences, making them ideal for impulse turbine power generation. Examples include the Shaping II Hydroelectric Power Station, Jinwo Hydroelectric Power Station, and Suwalong Hydroelectric Power Station. In addition, several world-class impulse turbine hydroelectric power stations are under construction or planned, such as the Lawa Hydroelectric Power Station, Yebatan Hydroelectric Power Station, and Zhala Hydroelectric Power Station.

[0003] An impulse turbine guides a high-speed free jet through a special water guide mechanism to impact the runner buckets tangentially, thereby driving the runner to rotate and converting water energy into mechanical energy. It is a highly efficient hydraulic prime mover that then drives the generator rotor to generate electricity. The runner bucket blades are made of martensitic stainless steel forgings, such as ZG06Cr13Ni5Mo (CA6NM), which have high strength and hardness. The working surface and back surface of the runner bucket blades are very complex, resembling a "double bowl" symmetrically separated by a ridge-like "water-dividing blade" in the middle. In particular, some large buckets have a diameter of more than 1 meter, so not only is the machining surface area large, but the machining of the internal cavity and welding bevel areas is also difficult, and the complex shape makes clamping difficult. Figure 1 This is a three-dimensional schematic diagram of the bucket of an impulse turbine, where a is the working surface and b is the back surface.

[0004] Typically, turbine buckets are machined using a gantry milling machine with an angle milling head. However, when machining the bucket end face, its complex shape makes the tool path difficult to observe, resulting in irregular tool advances and retreats. Frequent tool lifting and shifting lead to low machining efficiency and high risks in machining the bucket blade opening. For deeper areas of the bucket blade cavity, excessive tool overhang reduces feed rate and results in poor surface quality. For outer shape machining, frequent changes to the pressure plate position further reduce machining efficiency and the surface quality of the bucket back. Therefore, there is an urgent need to develop a new machining method to achieve efficient, precise, and stable machining of the entire surface of the turbine bucket forging. Summary of the Invention

[0005] In view of the above-mentioned technical status, the present invention provides a CNC forming and machining method for large water bucket parts for impact turbines, so as to solve the technical problem of high machining difficulty of existing large water bucket forgings for impact turbines.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] This invention provides a CNC forming method for large water bucket parts used in impact turbines, wherein the maximum size of the large water bucket parts is over 1 meter; the method includes the following steps:

[0008] S1: According to the center of gravity of the water bucket forging, weld the clamping block on the water bucket forging, use pads to support the lower right and lower left clamping blocks, use pressure plates to press the upper right and upper left clamping blocks, and clamp the water bucket forging on the floor boring machine according to the front position.

[0009] S2: Maintain the front working position and process auxiliary processing grooves;

[0010] S3: Maintain the front workstation and process in the order of the first processing area, the second processing area, and the third processing area;

[0011] S4: After the front station machining is completed, the bucket blade cavity is facing the worktable. Use adjustable shims to raise the water bucket mouth so that the water dividing blade is higher than the worktable. In step S1, the upper right and upper left clamping blocks press the upper pressure plates and clamp the water bucket forging on the floor boring machine according to the back station.

[0012] S5: The water bucket forging is clamped onto the floor boring machine according to the cutting groove position in the back station, and processed in the fourth processing area;

[0013] S6: Clamp the water bucket forging on the floor boring machine according to the root groove position in the back station, and perform the fifth machining area;

[0014] S7: Mount the water bucket forging on the floor boring machine according to the left side of the back side station in the back side station, and perform processing in the sixth processing area;

[0015] S8: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine and processed in the seventh processing area to finally obtain the water bucket part.

[0016] Furthermore, in step S2, the auxiliary processing grooves include a water inlet groove, a cutting groove, a water-dividing blade groove, and a water-blade cavity groove.

[0017] Furthermore, the water inlet process channel and the water-dividing blade process channel are open planes; the water inlet process channel includes a left water inlet process channel and a right water inlet process channel, wherein the left water inlet process channel includes the upper left water inlet process channel, the middle left water inlet process channel and the lower left water inlet process channel, and the right water inlet process channel includes the upper right water inlet process channel, the middle right water inlet process channel and the lower right water inlet process channel;

[0018] The cutting groove process groove includes a left cutting groove process groove and a right cutting groove process groove;

[0019] The bucket blade cavity process groove includes the left bucket blade cavity process groove and the right bucket blade cavity process groove.

[0020] Furthermore, the left and right middle water inlet process grooves are each composed of an open plane. Both the left and right middle water inlet process grooves are on the same plane as the highest point of the bucket blade cavity. The processing width of the left and right middle water inlet process grooves is comparable to the distance between the upper and lower water inlets of the final formed water bucket part, and is greater than the diameter of the processing cutter head.

[0021] The left and right cutting grooves are two U-shaped opening grooves. The bottom surface of the U-shaped opening groove is perpendicular to the Z-axis of the machine tool spindle. The machining depth of the U-shaped opening groove is consistent with the plane where the lowest point of the bucket blade opening is located after machining. The machining width of the U-shaped opening groove is greater than the diameter of the machining cutter head.

[0022] The upper left water inlet process groove, lower left water inlet process groove, upper right water inlet process groove, lower right water inlet process groove, water-dividing blade process groove, left bucket blade cavity process groove, and right bucket blade cavity process groove are each composed of multiple continuous stepped planes perpendicular to the Z-axis of the machine tool spindle. The inclined surfaces of the multiple steps are consistent with the shapes of the water inlet, water-dividing blade, and bucket blade cavity of the final formed water bucket part. The process groove step planes corresponding to the highest points of the water inlet and water-dividing blade are machined to the body of the final formed water bucket part.

[0023] Furthermore, the sum of the step machining width and the lateral depth of the step in the process grooves of the upper left water inlet, lower left water inlet, upper right water inlet, lower right water inlet, and water-dividing blade process grooves satisfies 0.8d≤K+M≤d; the sum of the step machining width and the lateral depth of the step in the process grooves of the left and right water blade cavities satisfies 0.6d≤K+M≤d; where d represents the diameter of the machining cutter head, K represents the machining width of the process groove step, and M represents the lateral depth of the process groove step, 10mm≤M≤20mm.

[0024] Furthermore, in step S3, the first processing area, the second processing area, and the third processing area are divided by a first dividing plane and a second dividing plane from top to bottom. The first dividing plane is perpendicular to the Z-axis of the machine tool spindle and is determined by the highest point of the bucket blade cavity. The second dividing plane is perpendicular to the Z-axis of the machine tool spindle and is determined by the lowest point of the cutting groove.

[0025] Furthermore, the first processing area is located above the first dividing plane and includes the upper left bucket blade inlet processing sub-area, the lower left bucket blade inlet processing sub-area, the upper right bucket blade inlet processing sub-area, the lower right bucket blade inlet processing sub-area, and the upper part of the water-dividing blade processing sub-area; the upper left bucket blade inlet processing sub-area, the lower left bucket blade inlet processing sub-area, the upper right bucket blade inlet processing sub-area, and the upper part of the water-dividing blade processing sub-area are processed independently; when processing the upper left bucket blade inlet processing sub-area... The cutter head rotates in a circular motion from the left middle water inlet process slot; when machining the lower left bucket blade inlet processing area, the cutter head rotates in a circular motion from the left middle water inlet process slot and the left cutting slot process slot; when machining the upper right bucket blade inlet processing area, the cutter head rotates in a circular motion from the right middle water inlet process slot; when machining the lower right bucket blade inlet processing area, the cutter head rotates in a circular motion from the right middle water inlet process slot and the right cutting slot process slot; when machining the water-dividing blade, the cutter head rotates in a circular motion from the left cutting slot process slot and the right cutting slot process slot.

[0026] Furthermore, the second processing area is located between the first and second dividing planes, including the upper left part of the bucket blade cavity, the upper right part of the bucket blade cavity and the middle part of the water-dividing blade, the left cutting groove reduction and the right cutting groove reduction, or the upper left part of the bucket blade cavity, the upper right part of the bucket blade cavity, the middle part of the water-dividing blade, the left cutting groove reduction, the right cutting groove reduction and the upper left part of the bucket back and the upper right part of the bucket back.

[0027] Furthermore, the third processing area is located below the second dividing plane, including the lower left part of the bucket blade cavity, the lower right part of the bucket blade cavity, and the lower part of the water-dividing blade.

[0028] Furthermore, in steps S5-S8, the fourth processing area includes the end face of the cutting groove and the blade back groove; the fifth processing area includes the end face of the root groove; the sixth processing area includes the left side of the bucket back; and the seventh processing area includes the right side of the bucket back.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. Based on the shape and size characteristics of the water bucket parts, this invention divides the surface of the water bucket forging into seven processing areas. The area division is scientific, which not only matches the shape of the parts but also meets the characteristics of machining. It reduces the drawbacks of frequent pressure plate replacement, making machining smooth and efficient. This provides a good processing method for the CNC machining of large water bucket parts for impact turbines.

[0031] 2. The auxiliary machining process groove of the present invention significantly increases the effective toolpath ratio, shortens the machining time, extends the average tool replacement cycle, improves machining stability, and improves overall manufacturing efficiency. Attached Figure Description

[0032] Figure 1 A three-dimensional schematic diagram of the water bucket of an impulse turbine;

[0033] Figure 2 This is a three-dimensional schematic diagram of the water bucket parts of the present invention;

[0034] Figure 3 for Figure 2 A 3D view of the left side of the water bucket component;

[0035] Figure 4 This is a three-dimensional schematic diagram of the water bucket forging of the present invention;

[0036] Figure 5 This is a schematic diagram of the centroid and clamping block of the front station of the water bucket forging of the present invention;

[0037] Figure 6 This is a schematic diagram showing the three-dimensional model of the water bucket part of the present invention contained within the three-dimensional model of the water bucket forging;

[0038] Figure 7 This is a schematic diagram of the auxiliary machining process groove on the front of the water bucket forging of the present invention;

[0039] Figure 8 for Figure 7 A side view of the stepped process tank;

[0040] Figure 9 This is a schematic diagram of two horizontal cross-sections of the processing area divided at the front of the water tank in this invention;

[0041] Figure 10 This is a schematic plan view of the first processing area of ​​the present invention;

[0042] Figure 11 This is a schematic diagram of the toolpath for the processing of each processing sub-region of the first processing area of ​​the present invention;

[0043] Figure 12 This is a three-dimensional schematic diagram of the second processing area of ​​the present invention;

[0044] Figure 13 This is a schematic plan view of the second processing area of ​​the present invention;

[0045] Figure 14 This is a schematic diagram of the toolpath for the machining process in the second machining area of ​​the present invention;

[0046] Figure 15 This is a three-dimensional schematic diagram of the third processing area of ​​the present invention;

[0047] Figure 16 This is a schematic plan view of the third processing area of ​​the present invention;

[0048] Figure 17 This is a schematic diagram of the toolpath for the machining process in the third machining area of ​​the present invention;

[0049] Figure 18 This is a schematic diagram of the fourth processing area of ​​the present invention;

[0050] Figure 19 This is a schematic diagram simulating the processing of the fourth processing area of ​​the present invention;

[0051] Figure 20 This is a schematic diagram of the fifth processing area of ​​the present invention;

[0052] Figure 21 This is a schematic diagram simulating the processing of the fifth processing area of ​​the present invention;

[0053] Figure 22 This is a schematic diagram of the sixth processing area of ​​the present invention;

[0054] Figure 23 This is a schematic diagram of the seventh processing area of ​​the present invention;

[0055] Figure 24 This is a schematic diagram simulating the processing of the sixth and seventh processing areas of the present invention;

[0056] Figure 25 This is a schematic diagram of the tool trajectory for machining the bucket blade opening in the present invention (comparative example).

[0057] Figure 26 This is a schematic diagram of the tool trajectory for machining the bucket blade cavity in the present invention (comparative example).

[0058] In the diagram: 100 - Water bucket part; 110 - Bucket blade cavity; 120 - Bucket back; 130 - Bucket blade opening; 140 - Root groove; 150 - Water-dividing blade; 160 - Cutting groove; 200 - Water bucket forging; 280 - Center of mass position of water bucket forging; 281 - Upper left clamping block of water bucket forging back; 282 - Upper right clamping block of water bucket forging back; 283 - Lower left clamping block of water bucket forging back; 284 - Lower right clamping block of water bucket forging back; O - XYZ - Basic coordinates in the 3D model of the water bucket part. System; o-xyz-Basic coordinate system of the 3D model of the water bucket forging; 230a-Upper left water bucket inlet process groove; 230b-Middle left water bucket inlet process groove; 230c-Lower left water bucket inlet process groove; 230d-Upper right water bucket inlet process groove; 230e-Middle right water bucket inlet process groove; 230f-Lower right water bucket inlet process groove; 260a-Left cutting groove process groove; 260b-Right cutting groove process groove; 210a-Left bucket blade cavity process groove; 210b-Right bucket blade cavity process groove; 250a-Water divider Blade groove; K - Groove width; 2X0 - Inclined surface; 2X0x - Groove; L - Length of the inclined surface in the transverse direction; H - Height of the inclined surface in the longitudinal direction; M - Depth of the groove step in the transverse direction; h - Height of the step; 001 - First dividing plane; 002 - Second dividing plane; 1301 - Upper left blade opening; 1302 - Lower left blade opening; 1303 - Upper right blade opening; 1304 - Lower right blade opening; 1501 - Upper part of the water-dividing blade; 1101 - Upper left part of the blade cavity ; 1102 - Upper right part of the bucket blade cavity; 1502 - Middle part of the water-dividing blade; 1601 - Left cutting groove; 1602 - Right cutting groove; 1201 - Upper left part of the bucket back; 1202 - Upper right part of the bucket back; 1103 - Lower left part of the bucket blade cavity; 1104 - Lower right part of the bucket blade cavity; 1503 - Lower part of the water-dividing blade; 1603 - End face of the cutting groove; 1203 - Groove on the back of the blade; 300 - Machining tool; 1401 - End face of the root groove; 1204 - Left side of the bucket back; 1205 - Right side of the bucket back. Detailed Implementation

[0059] The following detailed description, in conjunction with specific embodiments, provides a method for CNC forming of large water bucket parts for impact turbines. These embodiments are for illustrative purposes only, and the present invention is not limited to these embodiments.

[0060] The maximum size of the impact turbine water bucket of the present invention is over 1 meter, which belongs to the category of large water buckets. Figure 2 This is a three-dimensional schematic diagram of the water bucket component of the present invention. Figure 3 for Figure 2The left-side perspective view of the water bucket component shows that the water bucket component resembles a "double bowl" divided into two completely symmetrical parts by a central ridge-shaped water-dividing blade. Specifically, the water bucket component 100 includes a bucket blade cavity 110, a bucket back 120, a bucket blade opening 130, a root groove 140, a water-dividing blade 150, and a cutting groove 160. The water-dividing blade 150 extends vertically above the bucket blade opening 130, for example, by approximately 200 mm. Figure 4 This is a three-dimensional schematic diagram of the water bucket forging of the present invention. The water bucket forging 200 is a blank for the water bucket part. The outer dimensions of the water bucket forging are slightly larger than those of the water bucket part, while the inner cavity dimensions are slightly smaller than those of the water bucket part. The water bucket forging is machined to remove the excess parts to obtain the final water bucket part. It should be noted that there are no notches at the positions corresponding to the cutting grooves of the water bucket forging and the water bucket part. That is, the water bucket forging needs to be machined to completely carve out the cutting groove area, rather than modifying the existing cutting grooves of the water bucket forging.

[0061] In summary, based on the shape and size characteristics of various parts of the water bucket component and the basic shape of the water bucket forging, this invention proposes a CNC forming method for large water bucket components used in impact turbines, comprising the following steps:

[0062] S1: According to the center of gravity of the water bucket forging, weld the clamping block on the water bucket forging, use pads to support the lower right and lower left clamping blocks, use pressure plates to press the upper right and upper left clamping blocks, and clamp the water bucket forging on the floor boring machine according to the front position.

[0063] S2: Maintain the front working position and process auxiliary processing grooves;

[0064] S3: Maintain the front workstation and process in the order of the first processing area, the second processing area, and the third processing area;

[0065] S4: After the front station machining is completed, the bucket blade cavity is facing the worktable. Use adjustable shims to raise the water bucket mouth so that the water dividing blade is higher than the worktable. In step S1, the upper right and upper left clamping blocks press the upper pressure plates and clamp the water bucket forging on the floor boring machine according to the back station.

[0066] S5: The water bucket forging is clamped onto the floor boring machine according to the cutting groove position in the back station, and processed in the fourth processing area;

[0067] S6: Clamp the water bucket forging on the floor boring machine according to the root groove position in the back station, and perform the fifth machining area;

[0068] S7: Mount the water bucket forging on the floor boring machine according to the left side of the back side station in the back side station, and perform processing in the sixth processing area;

[0069] S8: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine and processed in the seventh processing area to finally obtain the water bucket part.

[0070] In step S1, the front position of the water bucket forging refers to the position where the bucket blade opening 130 is placed upwards, facing the Z-axis of the machine tool spindle, such as... Figure 1 Figure a in the middle or Figure 2 As shown.

[0071] Specifically, based on the center of gravity of the water bucket forging, four clamping blocks are welded to the upper left, upper right, lower left, and lower right sides of the water bucket forging, so that the water bucket forging can be machined in the front position facing the boring machine spindle. Figure 5 This is a schematic diagram of the centroid and clamping blocks of the front working position of the water bucket forging of the present invention. The centroid is 280, the upper left clamping block is 281, the upper right clamping block is 282, the lower left clamping block is 283, and the lower right clamping block is 284. The position of the centroid of the water bucket forging can be determined using 3D modeling software, such as UG.

[0072] It should be noted that the establishment of the front-side work position of the water bucket forging can be achieved using CAD software. Specifically, firstly, 3D scanning is used to create 3D models of both the water bucket part and the water bucket forging in the CAD software. The basic coordinate system O-XYZ is set in the 3D model of the water bucket part, and the basic coordinate system o-xyz is set in the 3D model of the water bucket forging. Then, the pose of the 3D model of the water bucket forging is adjusted so that the 3D model of the water bucket part is contained within the 3D model of the water bucket forging. The translation and rotation values ​​of the 3D model of the water bucket forging relative to the 3D model of the water bucket part are recorded. Finally, the water bucket forging is adjusted using the translation and rotation values ​​so that it is clamped on the floor boring machine in the front-side work position.

[0073] Specifically, creating a 3D model of the water bucket forging within the CAD software includes: using a gantry milling machine to machine 50mm x 50mm horizontal reference surfaces on both sides of the allowance above the bucket blade opening; and machining 50mm x 50mm angular reference surfaces on both sides of the allowance in front of the root groove. Then, a 3D scanner is used to scan the entire water bucket forging. During the scanning process, the coarse reference position needs to be accurately recorded, and the 3D model of the water bucket forging with the coarse reference is imported into the CAD software. Adjusting the pose of the 3D model of the water bucket forging involves translation and rotation, totaling 6 degrees of freedom. Figure 6 This is a schematic diagram showing the 3D model of the water bucket part of the present invention contained within the 3D model of the water bucket forging.

[0074] In step S2, Figure 7This is a schematic diagram of the auxiliary machining process grooves on the front of the water bucket forging of the present invention. The auxiliary machining process grooves consist of several stepped planes perpendicular to the Z-axis of the machine tool spindle, including a water bucket inlet process groove, a cutting groove process groove, a water-dividing blade process groove, and a bucket blade cavity process groove. The water bucket inlet process groove is located on the top surface of the water bucket inlet to be machined, including a left water bucket inlet process groove and a right water bucket inlet process groove. The left water bucket inlet process groove includes an upper left water bucket inlet process groove 230a, a middle left water bucket inlet process groove 230b, and a lower left water bucket inlet process groove 230c. The right water bucket inlet process groove includes an upper right water bucket inlet process groove 230d, a middle right water bucket inlet process groove 230e, and a lower right water bucket inlet process groove 230f. The cutting groove process groove is located on top of the cutting groove to be machined, including a left cutting groove process groove 260a and a right cutting groove process groove 260b. The bucket blade cavity process groove is located at the bottom of the bucket blade cavity to be processed, including the left bucket blade cavity process groove 210a and the right bucket blade cavity process groove 210b. The water-dividing blade process groove is located on the top surface of the water-dividing blade to be processed, including the water-dividing blade process groove 250a. Figure 7 In the example, K represents the machining width of all stepped planes in the water inlet process groove, cutting groove process groove, water-dividing blade process groove and bucket blade cavity process groove.

[0075] Specifically, the water inlet process groove and the water-dividing blade process groove are open planes. The left and right middle water inlet process grooves 230b and 230e are each composed of a plane. They are on the same plane as the highest point of the bucket blade cavity (the lowest point of the bucket blade inlet), that is, the machining depth extends to the body of the final formed water bucket part. Their machining width K is equivalent to the distance between the upper and lower water inlets of the final formed water bucket part. The cutting groove process groove consists of two U-shaped opening grooves, including the left cutting groove process groove 260a and the right cutting groove process groove 260b. They penetrate from the upper edge of the bucket back into the bucket blade cavity along the direction of the cutting groove to be processed, forming a V-shape. The bottom surface of the U-shaped opening groove is perpendicular to the Z-axis of the machine tool spindle. The machining depth of the cutting groove process groove is consistent with the plane where the lowest point of the bucket blade inlet is located after machining.

[0076] The machining width K of both the left and right center water inlet process grooves 230b and 230e is greater than the diameter of the machining cutter head. In other words, the distance between the upper and lower water inlets of the water inlet part determines the diameter of the machining cutter head; that is, the diameter of the machining cutter head cannot be greater than the distance between the upper and lower water inlets of the water inlet part. For example, if the distance between the upper and lower water inlets of the water inlet part is 250mm, the machining cutter head is D200R8. Similarly, the setting of the cutting groove process groove and its machining width K are greater than the diameter of the machining cutter head. In other words, the machining width K of the cutting groove process groove determines the diameter of the machining cutter head; that is, the diameter of the machining cutter head cannot be greater than the machining width K of the cutting groove process groove. For example, if the machining width K of the cutting groove process groove is 250mm, the machining cutter head is D200R8.

[0077] Since the top surfaces of the water inlet and the water-dividing blade of the water bucket part, as well as the bottom surface of the bucket blade cavity, are all inclined surfaces, the upper left water inlet process groove 230a, the lower left water inlet process groove 230c, the upper right water inlet process groove 230d, the lower right water inlet process groove 230f, the water-dividing blade process groove 250a, the left bucket blade cavity process groove 210a, and the right bucket blade cavity process groove 210b are each composed of multiple continuous stepped planes perpendicular to the Z-axis of the machine tool spindle. The direction of the steps is consistent with the shape of the bottom surface of the water inlet, the water-dividing blade, and the bucket blade cavity of the final formed water bucket part. The process groove step plane corresponding to the highest point of the water inlet and the water-dividing blade is machined to the body of the final formed water bucket part, that is, the highest point of the water inlet and the water-dividing blade.

[0078] Specifically, Figure 8 for Figure 7 This is a side view of a stepped process groove. The inclined plane 2X0 represents the top surface of the water inlet, the top surface of the water-dividing blade, or the bottom surface of the blade cavity. The dashed line represents the outline of the formed workpiece. 2X0x represents the process groove on it. L represents the horizontal length of the inclined plane, H represents the vertical height of the inclined plane, K represents the machining width of the process groove step, M represents the horizontal depth of the process groove step, and h represents the height of the step. It should be noted that since the process groove step plane corresponding to the highest point of the water inlet and water-dividing blade is machined to the final formed water inlet part body, the horizontal depth of the highest step of the process groove for the water inlet and water-dividing blade is 0mm. The M mentioned above refers to the horizontal depth of all process groove steps except for the highest step. For the blade cavity, the M mentioned above refers to the horizontal depth of all process groove steps.

[0079] Specifically, it is required that K+M≤d, where d represents the diameter of the machining head. Further, for the water-dividing blade and water inlet, 0.8d≤K+M≤d, such as K+M=0.9d; for the water-blade cavity, 0.6d≤K+M≤d, such as K+M=0.8d. Further, it can be limited to 10mm≤M≤20mm. It should be noted that limiting the maximum value of K+M aims to prevent tool damage due to tool embedding when the machine head rotates through the process groove to machine the top surface of the water-dividing blade, the top surface of the water-blade, or the bottom surface of the water-blade cavity, thus improving machining efficiency and the quality of the formed workpiece. Limiting the minimum value of K+M aims to reduce inefficient and useless toolpaths, improving machining efficiency. Limiting the maximum value of M aims to reduce the amount of cutting during forming, improving machining efficiency; limiting the minimum value of M aims to improve the surface quality of the formed workpiece and can appropriately reduce the workload of machining the process groove.

[0080] Under the premise of meeting the above-mentioned limiting conditions, the number of steps of the upper left water inlet process groove 230a, lower left water inlet process groove 230c, upper right water inlet process groove 230d, lower right water inlet process groove 230f, water-dividing blade process groove 250a, left bucket blade cavity process groove 210a and right bucket blade cavity process groove 210b are related to the size of the process groove steps, the diameter d of the machining cutter head and the size of the top surface of the water inlet, the top surface of the water-dividing blade and the bottom surface of the bucket blade cavity at the machining position.

[0081] Specifically, the minimum number of steps in the process grooves of the water inlet and the water divider. Minimum number of steps in the process groove of the bucket blade cavity In the formula N min M represents the minimum number of steps in the process tank. min The minimum depth of the process groove step in the horizontal direction is represented by d, and the diameter of the machining head is represented by L and M. min The unit of 'd' should be consistent with that of millimeters (mm), with the same symbol. This indicates rounding up, such as (LM). min ) / (dM min The calculation result for N is 4.1. min =5; (LM) min ) / (dM min The calculated result for N is 3.9. min =4; e.g. (LM) min ) / (dM min The calculation result for N is 5.0, then N min =5. Maximum number of steps in the water inlet and water-dividing blade process channel. Maximum number of steps in the process groove of the bucket blade cavity In the formula N max M represents the maximum number of steps in the process tank. max This represents the maximum depth of the process tank step in the transverse direction; other symbols are the same as above. The average height h of the step. avg =H / N, where h avg H represents the average height of the step, H represents the height of the slope in the longitudinal direction, and N represents the number of steps in the process groove.

[0082] In step S3, based on the shape and size characteristics of each part of the bucket component and the bucket forging, the corresponding processing part of the front station is divided into three processing areas by two horizontal cross sections from top to bottom. The first processing area includes the bucket blade opening and the upper part of the water-dividing blade processing area; the second processing area includes the upper part of the bucket blade cavity and the middle part of the water-dividing blade processing area, or the upper part of the bucket blade cavity, the upper part of the bucket back and the middle part of the water-dividing blade processing area; the third processing area includes the lower part of the bucket blade cavity and the lower part of the water-dividing blade processing area.

[0083] Since the water bucket forgings and water bucket parts are roughly the same shape, and the water bucket parts are standard parts, in order to clearly illustrate each machining area with reference to the drawing, Figure 2 The water bucket parts are illustrated in a three-dimensional diagram for further detailed explanation.

[0084] The machining area corresponding to the front station is divided into three machining areas by two horizontal cross sections from top to bottom. The horizontal cross section refers to the plane perpendicular to the Z-axis of the machine tool spindle when the front station is in operation. Figure 9 This is a schematic diagram of two horizontal cross-sections of the processing area on the front of the water bucket of the present invention. Specifically, the first dividing plane 001 is determined by the highest point of the bucket blade cavity 110 (the lowest point of the bucket blade opening 130), and the portion above the first dividing plane 001 is the first processing area. Figure 10 This is a schematic diagram of the first processing area of ​​the present invention. The processing area is divided into five independent processing sub-areas by the left middle water inlet process groove 230b, the right middle water inlet process groove 230e, the left cutting groove process groove 260a, and the right cutting groove process groove 260b. These are the upper left bucket blade inlet 1301 processing sub-area, the lower left bucket blade inlet 1302 processing sub-area, the upper right bucket blade inlet 1303 processing sub-area, the lower right bucket blade inlet 1304 processing sub-area, and the upper part of the water dividing blade 1501 processing sub-area. When machining the upper left bucket blade opening 1301 sub-area, the cutter head needs to rotate back and forth from the left middle water bucket opening process groove 230b; when machining the lower left bucket blade opening 1302 sub-area, the cutter head needs to rotate back and forth from the left middle water bucket opening process groove 230b and the left cutting groove process groove 260a; when machining the upper right bucket blade opening 1303 sub-area, the cutter head needs to rotate back and forth from the right middle water bucket opening process groove 230e; when machining the lower right bucket blade opening 1304 sub-area, the cutter head needs to rotate back and forth from the right middle water bucket opening process groove 230e and the right cutting groove process groove 260b; when machining the water-dividing blade, the cutter head rotates back and forth from the left cutting groove process groove 260a and the right cutting groove process groove 260b.

[0085] It should be noted that the five processing sub-areas of the first processing area—the upper left bucket blade inlet 1301 processing sub-area, the lower left bucket blade inlet 1302 processing sub-area, the upper right bucket blade inlet 1303 processing sub-area, the lower right bucket blade inlet 1304 processing sub-area, and the upper part of the water-dividing blade 1501 processing sub-area—are processed independently. Figure 11 This is a schematic diagram of the toolpath for the machining process in each sub-region of the first machining area of ​​the present invention. As can be seen from the diagram, the toolpath for each independent area is clear, and the tool entry and exit positions are all in a safe position outside the workpiece. The cutting efficiency is high, there are no inefficient and useless toolpaths such as empty tool transfer, and it is easy for the operator to observe during the actual machining, reducing the probability of human error.

[0086] The second dividing plane 002 below is determined by the lowest point of the cutting groove 160. The portion between the first dividing plane 001 and the second dividing plane 002 is the second processing area. Figure 12 This is a three-dimensional schematic diagram of the second processing area of ​​the present invention. Figure 13 This is a schematic diagram of the second processing area of ​​the present invention. The processing area includes the upper left part 1101 of the bucket blade cavity, the upper right part 1102 of the bucket blade cavity, the middle part 1502 of the water-dividing blade, the cutting of the left cutting groove 1601 and the cutting of the right cutting groove 1602, or the upper left part 1101 of the bucket blade cavity, the upper right part 1102 of the bucket blade cavity, the middle part 1502 of the water-dividing blade, the cutting of the left cutting groove 1601 and the cutting of the right cutting groove 1602, and the upper left part 1201 and the upper right part 1202 of the bucket back. It should be noted that, due to differences in the dimensions of different bucket parts or different bucket forgings, after the first processing area is completed, if the outer edge of the upper part of the bucket back extends beyond the outer edge of the bucket blade opening, the second processing area includes the upper left part 1201 and the upper right part 1202 of the bucket back; conversely, if the outer edge of the upper part of the bucket back does not extend beyond the outer edge of the bucket blade opening, the second processing area does not include the upper left part 1201 and the upper right part 1202 of the bucket back. In this case, the upper left part 1201 of the bucket back belongs to a part of the left side surface 1204 of the bucket back in the sixth processing area of ​​the subsequent step S7, and the upper right part 1202 of the bucket back belongs to a part of the right side surface 1205 of the bucket back in the seventh processing area of ​​the subsequent step S8. Figure 12 and Figure 13 The left cutting groove 1601 and right cutting groove 1602 in the figure are schematic diagrams of the water bucket part after forming. Therefore, these two parts are through holes. However, when processing in the second processing area, these two parts are not through holes. It is necessary to perform surface cutting on these two parts and only complete part of the cutting groove processing. After the processing in the fourth processing area in the subsequent step S5 is completed, the entire cutting groove processing is finally completed.

[0087] Figure 14This is a schematic diagram of the toolpath for the second processing area of ​​the present invention. Figure D shows the toolpath for the upper left part 1101 of the bucket blade cavity, the upper right part 1102 of the bucket blade cavity, the middle part 1502 of the water-dividing blade, the cutting of the left cutting groove 1601 and the cutting of the right cutting groove 1602, or the cutting of the upper left part 1101 of the bucket blade cavity, the upper right part 1102 of the bucket blade cavity, the middle part 1502 of the water-dividing blade, the cutting of the left cutting groove 1601 and the cutting of the right cutting groove 1602. Figure E shows the toolpath for the upper left part 1101 of the bucket blade cavity, the upper right part 1102 of the bucket blade cavity, the middle part 1502 of the water-dividing blade, the cutting of the left cutting groove 1601 and the cutting of the right cutting groove 1602, the upper left part 1201 of the bucket back and the upper right part 1202 of the bucket back. As can be seen from the figure, the second processing area places multiple processing parts in one plane for continuous processing. The toolpath is clear, and the tool entry and exit positions are all in a safe position outside the workpiece. The cutting efficiency is high, there are no inefficient and useless toolpaths such as empty tool transfer, and it is easy for the operator to observe during the actual processing, reducing the probability of human operation error.

[0088] The area below the second dividing plane 002 is the third processing area. Figure 15 This is a three-dimensional schematic diagram of the third processing area of ​​the present invention. Figure 16 This is a schematic diagram of the third processing area of ​​the present invention. The processing area includes the lower left part 1103 of the bucket blade cavity, the lower right part 1104 of the bucket blade cavity, and the lower right part 1503 of the water-dividing blade.

[0089] Figure 17 This is a schematic diagram of the toolpath for the third machining area of ​​the present invention. Figures A to C represent the toolpath diagrams for each stage of the machining process. As can be seen from the figures, after machining the process groove of the bucket blade cavity, the tool path consists of only one cut per cutting layer, and the path follows the outline of the bucket blade cavity. The tool entry and exit positions are both in safe positions outside the workpiece, resulting in high cutting efficiency and no inefficient or useless toolpaths such as empty tool transfer. This also facilitates observation by the operator during actual machining, reducing the probability of human error. Due to the large cutting volume here, the tool diameter needs to be larger than the machine tool spindle diameter to make the cutting more stable. When machining to the lowest point of the bucket blade cavity, a smaller diameter circular arc cutter head is used to extend the tool holder to machine the bevel residue at the bottom and root groove of the bucket blade cavity.

[0090] In step S4, the back-side station refers to the station where the bucket blade opening 130 is placed downwards and the bucket back 120 faces the Z-axis of the machine tool spindle, such as... Figure 1 As shown in Figure b.

[0091] In step S5, the cutting groove station in the back-side station refers to the station where the cutting groove faces the Z-axis of the machine tool spindle when the water tank is placed on the back side. The machining part corresponding to the cutting groove station is the fourth machining area, which includes the cutting groove end face and the blade back groove machining area. Figure 18 This is a schematic diagram of the fourth processing area of ​​the present invention, which includes a cutting groove end face 1603 and a blade back groove 1203.

[0092] Figure 19 This is a schematic diagram simulating the machining process in the fourth machining area of ​​the present invention. The machine tool spindle Z-axis is aligned with the cutting groove. A circular arc cutter head with a diameter larger than the spindle diameter is used to machine the end face of the cutting groove and the blade back groove. The depth direction is machined past the highest point of the workpiece, and the transverse machining area must include the highest point of the workpiece. Then, a smaller diameter circular arc cutter head is used to machine the blade back groove and part of the remaining blank at the cutting groove. Finally, an even smaller diameter ball end mill is used to machine the remaining remaining blank at the cutting groove.

[0093] In step S6, the root groove station in the back-side station refers to the station where the root groove faces the Z-axis of the machine tool spindle when the water tank is placed on the back side. The machining part corresponding to the root groove station is the fifth machining area, which includes the machining area of ​​the end face of the root groove. Figure 20 This is a schematic diagram of the fifth processing area of ​​the present invention, which includes the root groove end face 1401.

[0094] Figure 21 This is a schematic diagram simulating the processing of the fifth processing area of ​​the present invention. The Z-axis of the machine tool spindle is aligned with the root groove. An arc-shaped cutter head with a diameter larger than that of the spindle is used to process the outer contour. The depth direction is processed past the highest point of the workpiece. Then, a smaller diameter arc-shaped cutter head and an even smaller diameter ball end mill are used to process the residual blank at the weld bevel.

[0095] In step S7, the back left side station in the back station refers to the station where the left side of the water tank's back faces the Z-axis of the machine tool spindle when the water tank is placed back. The back left side station corresponds to the sixth machining area, which includes the water tank's back left side machining area. Figure 22 This is a schematic diagram of the sixth processing area of ​​the present invention, which includes the left side 1204 of the bucket back.

[0096] In step S8, the back right side station in the back station refers to the station where the right side of the water tank faces the Z-axis of the machine tool spindle when the water tank is placed back. The back right side station corresponds to the seventh machining area, which includes the right side machining area of ​​the water tank. Figure 23 This is a schematic diagram of the seventh processing area of ​​the present invention, which includes the right side 1205 of the bucket back.

[0097] In steps S7 and S8, the machine tool spindle faces the side of the workpiece, and the position of the pressure plate is adjusted so that the pressure plate is placed on the upper part of the blade back groove.

[0098] Figure 24 This is a schematic diagram simulating the machining process in the sixth and seventh machining areas of the present invention. The machine tool spindle faces the side of the workpiece, and an arc-shaped cutter head with a diameter larger than the spindle diameter is used to machine the outer contour, and the depth direction is machined past the highest point of the workpiece.

[0099] It should be noted that the machining allowance in steps S2-S8 is determined according to the encapsulation allowance of the 3D model of the water bucket part in the CAD software in step S1, which is contained within the 3D model of the water bucket forging.

[0100] The processing method of the present invention shortens the processing time and improves processing efficiency and stability.

[0101] Example

[0102] The maximum dimensions of the large bucket of the impulse turbine are 1.6 meters, with a maximum length of 1.63 meters and a maximum width of 1.5 meters; the distance between the highest and lowest points of the bucket blade opening, i.e., the maximum net height of the bucket blade opening, is 100 mm, and the thickness of the bucket blade opening is 80 mm; the minimum thickness of the bucket blade cavity is 80 mm, and the maximum net depth is 500 mm; the maximum height of the water-dividing blade is 0.7 m, and the maximum length is 0.8 m; the maximum height of the bucket back is 0.7 m; the maximum length of the root groove is 1.0 meter and the maximum width is 0.5 meters; and the maximum length of the cutting groove is 400 mm and the maximum width is 150 mm.

[0103] The external dimensions of the water bucket forging should be slightly larger than those of the water bucket part, averaging 5mm higher in height and 50mm higher in length and width. The internal cavity dimensions of the water bucket forging should be slightly smaller than those of the water bucket part, with the largest difference occurring at the lowest point of the internal cavity, which is 300mm higher than that of the water bucket part.

[0104] A CNC forming method for large water bucket parts used in impulse turbines includes the following steps:

[0105] S1: According to the center of gravity of the water bucket forging, weld the clamping block on the water bucket forging, use pads to support the lower right and lower left clamping blocks, use pressure plates to press the upper right and upper left clamping blocks, and clamp the water bucket forging on the floor boring machine according to the front position.

[0106] The front position of the water bucket forging refers to the position where the bucket blade opening faces upwards, with the opening facing the Z-axis of the machine tool spindle. Specifically, based on the center of gravity of the water bucket forging, four clamping blocks (upper left, upper right, lower left, and lower right) are welded to the back side of the bucket forging, ensuring the water bucket forging is in the front position directly facing the boring machine spindle for machining. The center of gravity of the water bucket forging is determined using UG drawing software. The lower left and lower right clamping blocks are symmetrical about the workpiece's central axis, spaced 600mm apart, with the lowest point of the water bucket forging 350mm above the machine tool bed surface. The upper left and upper right clamping blocks are symmetrical about the workpiece's central axis, spaced 1300mm apart, and 600mm from the lowest point of the water bucket forging, ensuring the water bucket forging is in the front position directly facing the boring machine spindle for machining.

[0107] The front-side mounting position of the water bucket forging is established using CAD software. Specifically, firstly, 3D scanning is used to create 3D models of both the water bucket part and the water bucket forging in the CAD software. A basic coordinate system O-XYZ is set in the 3D model of the water bucket part, and a basic coordinate system o-xyz is set in the 3D model of the water bucket forging. Then, the pose of the 3D model of the water bucket forging is adjusted so that the 3D model of the water bucket part is contained within the 3D model of the water bucket forging. The translation and rotation values ​​of the 3D model of the water bucket forging relative to the 3D model of the water bucket part are recorded. Finally, the water bucket forging is adjusted using the translation and rotation values ​​so that it is clamped on the floor boring machine in the front-side mounting position.

[0108] Specifically, creating a 3D model of the water bucket forging in the CAD software includes: using a gantry milling machine to machine 50mm x 50mm horizontal reference surfaces on both sides of the allowance above the bucket blade opening; and machining 50mm x 50mm angular reference surfaces on both sides of the allowance in front of the root groove. Then, a 3D scanner is used to scan the entire water bucket forging, accurately recording the rough reference position during the scanning process. The 3D model of the water bucket forging with the rough reference is then imported into the CAD software. Adjusting the pose of the 3D model of the water bucket forging involves six degrees of freedom: translation and rotation. The spatial translation values ​​X = -3.2mm, Y = 1.4mm, Z = -5mm and the rotation values ​​Rx = 0.5°, Ry = -0.6° are determined between the two poses. This pose of the 3D model of the water bucket forging is maintained, and a new finishing reference is created on the allowance.

[0109] S2: Maintain the front working position and process auxiliary processing grooves;

[0110] The auxiliary machining process grooves consist of several stepped planes perpendicular to the Z-axis of the machine tool spindle, including a water inlet process groove, a cutting groove process groove, a water-dividing blade process groove, and a bucket blade cavity process groove. The water inlet process groove is located on the top surface of the water inlet to be machined, and includes a left water inlet process groove and a right water inlet process groove. The left water inlet process groove includes an upper left water inlet process groove, a middle left water inlet process groove, and a lower left water inlet process groove; the right water inlet process groove includes an upper right water inlet process groove, a middle right water inlet process groove, and a lower right water inlet process groove. The cutting groove process groove is located on top of the cutting groove to be machined, and includes a left cutting groove process groove and a right cutting groove process groove. The bucket blade cavity process groove is located at the bottom of the bucket blade cavity to be machined, and includes a left bucket blade cavity process groove and a right bucket blade cavity process groove. The water-dividing blade process groove is located on the top surface of the water-dividing blade to be machined, and includes a water-dividing blade process groove.

[0111] Specifically, the water inlet groove and the water-dividing blade groove are open planes. The left and right middle water inlet grooves are each composed of a plane, and they are on the same plane as the highest point of the bucket blade cavity (the lowest point of the bucket blade inlet), meaning the machining depth extends to the final formed water bucket part body. Their machining width K = 250mm is equivalent to the distance between the upper and lower water inlets of the final formed water bucket part. The cutting groove is composed of two U-shaped opening grooves, including the left and right cutting grooves. They penetrate from the upper edge of the bucket back into the bucket blade cavity along the direction of the cutting groove to be processed, forming a V-shape. The bottom surface of the U-shaped opening groove is perpendicular to the Z-axis of the machine tool spindle. The machining depth of the cutting groove is consistent with the plane where the lowest point of the formed bucket blade inlet is located, and the width is 250mm.

[0112] The machining width K of both the left and right center water inlet process grooves is greater than the diameter of the machining cutter head. In other words, the distance between the upper and lower water inlets of the water inlet part determines the diameter of the machining cutter head; that is, the diameter of the machining cutter head cannot be greater than the distance between the upper and lower water inlets of the water inlet part. The distance between the upper and lower water inlets of the water inlet part is 250mm, and the machining cutter head is D200R8. Similarly, the setting of the cutting groove process groove and its machining width K being greater than the diameter of the machining cutter head, or in other words, the machining width K of the cutting groove process groove determines the diameter of the machining cutter head; that is, the diameter of the machining cutter head cannot be greater than the machining width K of the cutting groove process groove. The machining width K of the cutting groove process groove is 250mm, and the machining cutter head is D200R8.

[0113] Since the top surfaces of the water inlet and the water-dividing blade of the water bucket part, as well as the bottom surface of the bucket blade cavity, are all inclined surfaces, the upper left water inlet process groove, the lower left water inlet process groove, the upper right water inlet process groove, the lower right water inlet process groove, the water-dividing blade process groove, the left bucket blade cavity process groove, and the right bucket blade cavity process groove are each composed of multiple continuous stepped planes perpendicular to the Z-axis of the machine tool spindle. The direction of the steps is consistent with the shape of the bottom surface of the water inlet, the water-dividing blade, and the bucket blade cavity of the final formed water bucket part. The process groove step plane corresponding to the highest point of the water inlet and the water-dividing blade is machined to the body of the final formed water bucket part, that is, the highest point of the water inlet and the water-dividing blade.

[0114] The horizontal length L of the top surface of the water inlet is 600mm, the vertical height H of the top surface of the water inlet is 100mm, the horizontal depth M of the process groove step is 15mm, the machining width K of the process groove step is 165mm, K+M is 180mm, the diameter d of the machining cutter head is 200mm, the number of steps N of the process groove is 4, and the height h of the step is 25mm.

[0115] The horizontal length L of the top surface of the drain hopper is 900mm, the vertical height H of the top surface of the drain hopper is 100mm, the horizontal depth M of the process groove step is 15mm, the machining width K of the process groove step is 165mm, K+M is 180mm, the diameter d of the machining cutter head is 200mm, the number of process groove steps N is 5, and the height h of the step is 20mm.

[0116] The horizontal length L of the top surface of the water-dividing blade is 800mm, the vertical height H of the top surface of the water-dividing blade is 100mm, the horizontal depth M of the process groove step is 15mm, the machining width K of the process groove step is 165mm, K+M is 180mm, the diameter d of the machining cutter head is 200mm, the number of steps N of the process groove is 5, and the height h of the step is 20mm.

[0117] The length L of the bottom surface of the bucket blade cavity in the transverse direction is 950mm, the height H of the bottom surface of the bucket blade cavity in the longitudinal direction is 300mm, the depth M of the process groove step in the transverse direction is 10mm, the machining width K of the process groove step is 130mm, K+M is 140mm, the diameter d of the machining cutter head is 200mm, the number of steps N of the process groove is 5, and the height h of the step is 60mm.

[0118] S3: Maintain the front workstation and process in the order of the first processing area, the second processing area, and the third processing area;

[0119] The corresponding processing part of the front station is divided into three processing areas by two horizontal cross sections from top to bottom. The first processing area includes the processing area of ​​the bucket blade opening and the upper part of the water-dividing blade; the second processing area includes the processing area of ​​the upper part of the bucket blade cavity and the middle part of the water-dividing blade, or the processing area of ​​the upper part of the bucket blade cavity, the upper part of the bucket back and the middle part of the water-dividing blade; the third processing area includes the processing area of ​​the lower part of the bucket blade cavity and the lower part of the water-dividing blade.

[0120] The machining section corresponding to the front workstation is divided into three machining areas by two horizontal cross-sections from top to bottom. The horizontal cross-sections refer to the plane perpendicular to the Z-axis of the machine tool spindle when in the front workstation position. Specifically, the first dividing plane is determined by the highest point of the bucket blade cavity (the lowest point of the bucket blade opening), 100mm away from the highest point of the bucket blade cavity. The part above the first dividing plane is the first machining area. This machining area is divided into five independent machining sub-areas by the left middle water bucket opening process groove, the right middle water bucket opening process groove, the left cutting groove process groove, and the right cutting groove process groove, namely the upper left bucket blade opening machining sub-area, the lower left bucket blade opening machining sub-area, the upper right bucket blade opening machining sub-area, the lower right bucket blade opening machining sub-area, and the upper part of the water dividing blade machining sub-area. When machining the upper left bucket blade inlet sub-area, the cutter head needs to rotate back and forth from the left middle bucket blade inlet process groove; when machining the lower left bucket blade inlet sub-area, the cutter head needs to rotate back and forth from the left middle bucket blade inlet process groove and the left cutting groove process groove; when machining the upper right bucket blade inlet sub-area, the cutter head needs to rotate back and forth from the right middle bucket blade inlet process groove; when machining the lower right bucket blade inlet sub-area, the cutter head needs to rotate back and forth from the right middle bucket blade inlet process groove and the right cutting groove process groove; when machining the water-dividing blade, the cutter head rotates back and forth from the left cutting groove process groove and the right cutting groove process groove.

[0121] The five processing sub-areas of the first processing area—the upper left bucket blade inlet processing sub-area, the lower left bucket blade inlet processing sub-area, the upper right bucket blade inlet processing sub-area, the lower right bucket blade inlet processing sub-area, and the upper part of the water-dividing blade processing sub-area—are processed independently. Figure 11 This is a schematic diagram of the toolpath for the machining process of each sub-region of the first machining area in this embodiment.

[0122] The second dividing plane below is determined by the lowest point of the cutting groove and is 200mm away from the first dividing plane. The part between the first dividing plane and the second dividing plane is the second processing area, which includes the upper left part of the bucket blade cavity, the upper right part of the bucket blade cavity and the middle part of the water-dividing blade, the left cutting groove reduction and the right cutting groove reduction. Figure 14 Figure D is a schematic diagram of the toolpath for the machining process in the second machining area of ​​this embodiment.

[0123] The portion below the second dividing plane is the third processing area, which includes the lower left part of the bucket blade cavity, the lower right part of the bucket blade cavity, and the lower right part of the water-dividing blade. Figure 17 This is a schematic diagram of the toolpath for the machining process in the third machining area of ​​this embodiment. Figures A to C represent the toolpath schematic diagrams for each stage of the machining process.

[0124] S4: After the front station machining is completed, the bucket blade cavity is facing the worktable. Use adjustable shims to raise the water bucket mouth so that the water dividing blade is higher than the worktable. In step S1, the upper right and upper left clamping blocks press the upper pressure plates and clamp the water bucket forging on the floor boring machine according to the back station.

[0125] A back-side workstation refers to a workstation where the bucket blades are placed downwards and the back of the bucket faces the Z-axis of the machine tool spindle.

[0126] S5: The water bucket forging is clamped onto the floor boring machine according to the cutting groove position in the back station, and processed in the fourth processing area;

[0127] The cutting groove station in the back-side workstation refers to the station where the cutting groove faces the Z-axis of the machine tool spindle when the water tank is placed on the back side. The machining part corresponding to the cutting groove station is the fourth machining area, which includes the machining area of ​​the cutting groove end face and the blade back groove.

[0128] Figure 19 This is a schematic diagram simulating the machining process in the fourth machining area of ​​this embodiment. The machine tool spindle Z-axis faces the cutting groove. A circular arc cutter head with a diameter larger than the spindle diameter (160mm spindle diameter, 200mm cutter head diameter) is used to machine the end face of the cutting groove and the blade back groove. The depth direction machining extends past the highest point of the workpiece, 1000mm from the starting end face of the cutting groove. The transverse machining area must include the highest point of the workpiece. Then, a smaller diameter circular arc cutter head (125mm diameter) is used to machine the blade back groove and some remaining blank at the cutting groove. Finally, an even smaller diameter ball end mill (40mm diameter) is used to machine the remaining remaining blank at the cutting groove.

[0129] S6: Clamp the water bucket forging on the floor boring machine according to the root groove position in the back station, and perform the fifth machining area;

[0130] The root groove station in the back-side workstation refers to the station where the root groove faces the Z-axis of the machine tool spindle when the water tank is placed on the back side. The machining part corresponding to the root groove station is the fifth machining area, which includes the machining area of ​​the end face of the root groove.

[0131] Figure 21 This is a schematic diagram simulating the machining process in the fifth machining area of ​​this embodiment. The Z-axis of the machine tool spindle is directly opposite the root groove. A circular arc cutter head with a diameter larger than the spindle diameter is used to machine the outer contour. The cutter head diameter is 200mm. The depth direction is machined past the highest point of the workpiece, 700mm away from the starting end face of the root groove at this station. Then, a smaller diameter circular arc cutter head and an even smaller diameter ball end mill are used. Circular arc cutter heads with diameters of 125mm and 63mm, and a ball end mill with a diameter of 40mm are used in sequence to machine the residual blank at the weld bevel.

[0132] S7: Mount the water bucket forging on the floor boring machine according to the left side of the back side station in the back side station, and perform processing in the sixth processing area;

[0133] The back-side workstation in the context of back-side workstations refers to the workstation where, when the water tank is placed with its back side facing the Z-axis of the machine tool spindle. The back-side workstation corresponds to the sixth machining area, which includes the machining area for the left side of the water tank's back side.

[0134] S8: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine and processed in the seventh processing area to finally obtain the water bucket part.

[0135] The back-side workstation in the context of back-side workstations refers to the workstation where, when the water tank is placed back-side down, the right side of the tank's back faces the Z-axis of the machine tool spindle. The back-side workstation corresponds to the seventh machining area, which includes the machining area for the right side of the water tank's back.

[0136] In steps S7 and S8, the machine tool spindle faces the side of the workpiece, and the position of the pressure plate is adjusted so that the pressure plate is placed on the upper part of the blade back groove.

[0137] Figure 24 This is a schematic diagram simulating the machining process in the sixth and seventh machining areas of this embodiment. The machine tool spindle faces the side of the workpiece, and an arc-shaped cutter head with a diameter larger than the spindle diameter is used to machine the outer contour. The spindle diameter is 160mm, and the cutter head diameter is 200mm. The depth direction is machined past the highest point of the workpiece, 400mm away from the starting surface of the workpiece side at this station.

[0138] The machining allowance in steps S2-S8 is determined according to the encapsulation allowance of the 3D model of the water bucket part in the CAD software in step S1, which is contained within the 3D model of the water bucket forging.

[0139] The manufacturing efficiency of this embodiment is shown in Table 1.

[0140] Comparative Example

[0141] This comparative example follows conventional machining processes, using a gantry milling machine to perform full-surface machining on the water bucket forging. No machining zones or process grooves are created; machining is performed only on specific parts of the water bucket component. The machining is divided into five areas: the bucket blade opening (including the upper part of the water-dividing blade), the bucket blade cavity (including the middle and lower part of the water-dividing blade), the middle part of the bucket back bottom (including some cutting grooves), and the upper part of the bucket back (including the remaining cutting grooves). The machining steps are as follows:

[0142] Step T1: Machining the bucket blade opening (including the upper part of the water-dividing blade): The bucket blade cavity of the water bucket forging is placed flat on the worktable with the clamping position set in the two bucket blade cavities, and machining is performed using a 315mm diameter arc cutter head; Figure 25 This is a schematic diagram of the tool path for machining the bucket blade opening in a comparative manner. In the diagram, light blue represents the effective tool path, while red and dark blue represent the ineffective tool paths such as tool movement and tool shifting.

[0143] Step T2, Machining the bucket blade cavity (including the lower part of the water-dividing blade): The bucket blade cavity of the water bucket forging is placed flat on the worktable with the bucket blade cavity facing upward. The clamping positions are set at four evenly distributed positions on the plane of the bucket blade opening. The upper and middle parts of the bucket blade cavity are machined using a 315mm diameter arc cutter head. When machining to the bottom of the bucket blade cavity, the tool is changed. The 125mm diameter and 63mm diameter arc cutter heads are used for machining in sequence. Figure 26 This is a schematic diagram of the tool path for machining the bucket blade cavity in this comparative example. In the diagram, light blue represents the effective tool path, while red and dark blue represent the ineffective tool paths such as tool movement and tool shifting.

[0144] Step T3: Machining the middle part of the bucket back bottom (including part of the cutting groove): Place the bucket forging with the bucket back facing up on the worktable, raise and level the bucket forging, press the pressure plate on both ends of the water-dividing blade, and use a 315mm diameter arc cutter head to machine the middle part of the bucket back bottom.

[0145] Step T4: Machining the upper part of the bucket back (including the remaining cutting groove): Place the bucket forging with the bucket back facing up on the worktable, raise and level the bucket forging, press the pressure plate on the highest point of the bucket back at this station, and use a 315mm diameter arc cutter head to machine the upper part of the bucket back.

[0146] Step T5: Machining the root groove: Place the water bucket forging with the bucket back facing up on the worktable, raise and level the water bucket forging, press the pressure plate on the middle groove of the bucket back on the cutting groove side, and use a 315mm diameter arc cutter head to machine the root groove.

[0147] The manufacturing efficiency of the comparative figures is shown in Table 1.

[0148] Will Figure 11 , Figure 14 (D) Figure 17 and Figure 25-26 As can be seen from the comparison, the number of invalid toolpaths in the comparative machining of the bucket blade opening and bucket blade cavity is significantly increased compared to the example, indicating that the machining method of the example improves machining efficiency.

[0149] Table 1 Manufacturing efficiency of the examples and comparative examples

[0150]

[0151]

[0152] As shown in Table 1, except for the root groove where the manufacturing efficiency of the embodiment and the comparative example is the same, the processing time, average tool change cycle, and processing stability of the embodiment are significantly better than those of the comparative example in the other processing areas. The total processing time of the embodiment is 208 hours, while that of the comparative example is 323 hours, less than 65% of that of the comparative example. Furthermore, the effective toolpath ratio of the first to third processing areas of the embodiment is 96-98%, which is significantly higher than the 80-83% of the comparative example. Therefore, the overall manufacturing efficiency of the embodiment is significantly higher than that of the comparative example.

[0153] The above description of the present invention represents only some embodiments, but the present invention is not limited to the specific implementations described above. The specific implementations described above are illustrative and not restrictive. All specific extensions using the materials and methods of the present invention, without departing from the spirit and scope of the claims, are within the protection scope of the present invention.

Claims

1. A CNC forming method for large water bucket parts used in impact turbines, characterized in that, The maximum size of the large water tank component is over 1 meter; the method includes the following steps: S1: According to the center of gravity of the water bucket forging, weld the clamping block on the water bucket forging, use pads to support the lower right and lower left clamping blocks, use pressure plates to press the upper right and upper left clamping blocks, and clamp the water bucket forging on the floor boring machine according to the front position. S2: Maintain the front working position and process the auxiliary processing grooves; the auxiliary processing grooves include the water inlet groove, the cutting groove, the water-dividing blade groove, and the water blade cavity groove. S3: Maintain the front workstation and process in the order of the first processing area, the second processing area, and the third processing area; S4: After the front station is finished, the bucket blade cavity is facing the worktable. Use adjustable shims to raise the water bucket mouth so that the water dividing blade is higher than the worktable. In step S1, press the upper right and upper left clamping blocks on the upper pressure plate and clamp the water bucket forging on the floor boring machine according to the back station. S5: The water bucket forging is clamped onto the floor boring machine according to the cutting groove position in the back station, and processed in the fourth processing area; S6: Clamp the water bucket forging on the floor boring machine according to the root groove position in the back station, and perform the fifth machining area; S7: Mount the water bucket forging on the floor boring machine according to the left side of the back side station in the back side station, and perform processing in the sixth processing area; S8: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine and processed in the seventh processing area to finally obtain the water bucket part.

2. The method according to claim 1, characterized in that, The water inlet process channel and the water-dividing blade process channel are open planes; the water inlet process channel includes a left water inlet process channel and a right water inlet process channel, wherein the left water inlet process channel includes an upper left water inlet process channel, a middle left water inlet process channel and a lower left water inlet process channel, and the right water inlet process channel includes an upper right water inlet process channel, a middle right water inlet process channel and a lower right water inlet process channel; The cutting groove process groove includes a left cutting groove process groove and a right cutting groove process groove; The bucket blade cavity process groove includes a left bucket blade cavity process groove and a right bucket blade cavity process groove.

3. The method according to claim 2, characterized in that, The left and right middle water inlet process grooves are each composed of an open plane. The left and right middle water inlet process grooves are on the same plane as the highest point of the water inlet cavity. The processing width of the left and right middle water inlet process grooves is comparable to the distance between the upper and lower water inlets of the final formed water inlet part, and is greater than the diameter of the processing cutter disc. The left and right cutting grooves are two U-shaped opening grooves. The bottom surface of the U-shaped opening groove is perpendicular to the Z-axis of the machine tool spindle. The machining depth of the U-shaped opening groove is consistent with the plane where the lowest point of the bucket blade opening is located after machining. The machining width of the U-shaped opening groove is greater than the diameter of the machining cutter head. The upper left water inlet process groove, the lower left water inlet process groove, the upper right water inlet process groove, the lower right water inlet process groove, the water-dividing blade process groove, the left water blade cavity process groove, and the right water blade cavity process groove are each composed of multiple continuous stepped planes perpendicular to the Z-axis of the machine tool spindle. The inclined surfaces of the multiple steps are consistent with the shapes of the water inlet, water-dividing blade, and water blade cavity of the final formed water bucket part. The process groove step planes corresponding to the highest points of the water inlet and water-dividing blade are machined to the body of the final formed water bucket part.

4. The method according to claim 3, characterized in that, The sum of the step processing width and the horizontal depth of the step in the upper left water inlet process groove, the lower left water inlet process groove, the upper right water inlet process groove, the lower right water inlet process groove, and the water-dividing blade process groove satisfies 0.8d≤K+M≤d; the sum of the step processing width and the horizontal depth of the step in the left bucket blade cavity process groove and the right bucket blade cavity process groove satisfies 0.6d≤K+M≤d; where d represents the diameter of the machining cutter head, K represents the processing width of the process groove step, and M represents the horizontal depth of the process groove step, 10mm≤M≤20mm.

5. The method according to claim 1, characterized in that, In step S3, the first processing area, the second processing area, and the third processing area are divided by a first dividing plane and a second dividing plane from top to bottom. The first dividing plane is perpendicular to the Z-axis of the machine tool spindle and is determined by the highest point of the bucket blade cavity. The second dividing plane is perpendicular to the Z-axis of the machine tool spindle and is determined by the lowest point of the cutting groove.

6. The method according to claim 5, characterized in that, The first processing area is located above the first dividing plane and includes the upper left bucket blade inlet processing sub-area, the lower left bucket blade inlet processing sub-area, the upper right bucket blade inlet processing sub-area, the lower right bucket blade inlet processing sub-area, and the upper part of the water-dividing blade processing sub-area; the upper left bucket blade inlet processing sub-area, the lower left bucket blade inlet processing sub-area, the upper right bucket blade inlet processing sub-area, and the upper part of the water-dividing blade processing sub-area are processed independently; when processing the upper left bucket blade inlet processing sub-area, the cutter head rotates and moves from the left middle water bucket inlet process groove; When machining the lower left bucket blade inlet machining area, the cutter head rotates back and forth from the left middle water bucket inlet process groove and the left cutting groove process groove; when machining the upper right bucket blade inlet machining area, the cutter head rotates back and forth from the right middle water bucket inlet process groove. When machining the lower right bucket blade inlet machining area, the cutter head rotates back and forth from the right middle water bucket inlet process slot and the right cutting slot process slot; when machining the water-dividing blade, the cutter head rotates back and forth from the left cutting slot process slot and the right cutting slot process slot.

7. The method according to claim 5, characterized in that, The second processing area is located between the first dividing plane and the second dividing plane, including the upper left part of the bucket blade cavity, the upper right part of the bucket blade cavity and the middle part of the water-dividing blade, the left cutting groove reduction and the right cutting groove reduction, or the upper left part of the bucket blade cavity, the upper right part of the bucket blade cavity, the middle part of the water-dividing blade, the left cutting groove reduction, the right cutting groove reduction and the upper left part of the bucket back and the upper right part of the bucket back.

8. The method according to claim 5, characterized in that, The third processing area is located below the second dividing plane and includes the lower left part of the bucket blade cavity, the lower right part of the bucket blade cavity, and the lower part of the water-dividing blade.

9. The method according to claim 1, characterized in that, In steps S5-S8, the fourth processing area includes the cutting groove end face and the blade back groove; the fifth processing area includes the root groove end face; the sixth processing area includes the left side of the bucket back; and the seventh processing area includes the right side of the bucket back.

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