Numerical control forming design and machining method of large water bucket part for impulse turbine

Abstract

The invention provides a numerical control forming design and machining method for a large water bucket part for an impulse turbine, belongs to the technical field of machining, and solves the technical problem that an existing large water bucket forge piece for the impulse turbine is high in machining difficulty. The numerical control forming design method comprises the following steps: step 1, establishing a three-dimensional model of the water bucket part; 2, outputting the three-dimensional model of the water bucket forge piece into a software CAD function; 3, the three-dimensional model of the water bucket part is contained in the three-dimensional model of the water bucket forge piece, and a translation value and a rotation value are recorded; step 4, designing a clamping position during front station processing of the water bucket forge piece; 5, designing and dividing all-surface machining stations and all machining areas; 6, an auxiliary machining process groove is designed; and 7, setting a machining tool path, generating a machining tool path code, and generating a numerical control program after post-processing. The machining time is shortened, the average replacement period of the blade is prolonged, and the manufacturing efficiency is improved.

Description

Technical Field

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

[0002] China's unique three-tiered, terraced topography, sloping from west to east, has given rise to a large number of impulse turbine hydroelectric power stations. These are almost entirely concentrated in the high mountains and deep valleys of the southwestern plateau regions, including Sichuan, Yunnan, and Tibet. The rivers in these areas have very large drops (water heads), making them ideal for impulse turbine power generation, as exemplified by the Shaping II Hydroelectric Power Station, Jinwo Hydroelectric Power Station, and Suwalong Hydroelectric Power Station. In addition, there are several world-class impulse turbine hydroelectric power stations under construction or in the planning stages, 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 water 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 design and processing method for large water bucket parts for impact turbines, so as to solve the technical problem of high processing 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 design method for large water bucket parts used in impulse turbines, wherein the maximum size of the large water bucket parts is over 1 meter; the method includes the following steps:

[0008] Step 1: Enable the CAD function of the software and create a 3D model of the water bucket parts;

[0009] Step 2: Machining a rough datum for the water bucket forging, then performing 3D scanning and outputting the 3D model of the water bucket forging into the CAD function of the software;

[0010] Step 3: Adjust the pose of the 3D model of the water bucket forging so that the 3D model of the water bucket part is contained within the 3D model of the water bucket forging. Record the translation and rotation values ​​of the 3D model of the water bucket forging relative to the 3D model of the water bucket part. Then, make a new finishing datum on the allowance according to the rough datum in Step 2.

[0011] Step 4: Based on the centroid position and finishing datum of the 3D model of the water bucket forging, design the clamping position for machining the front of the water bucket forging.

[0012] Step 5: Based on the shape and size characteristics of each part of the water bucket parts and water bucket forgings, design and divide the workstations and processing areas for full surface machining;

[0013] Step 6: Design auxiliary machining process grooves according to the machining area corresponding to the front station of the water bucket forging;

[0014] Step 7: Enable the CAM function in the software, select the cavity milling mode, set the machining toolpaths in each machining area of ​​the 3D model of the water bucket forging, generate the machining toolpath code, and generate the CNC program after post-processing.

[0015] Furthermore, in step 5, the workstation includes a front workstation and a back workstation; the front workstation corresponds to the first processing area, the second processing area, and the third processing area; the back workstation corresponds to the fourth processing area, the fifth processing area, the sixth processing area, and the seventh processing area.

[0016] Furthermore, the first processing area is located above the first dividing plane and includes the upper left bucket blade opening processing sub-area, the lower left bucket blade opening processing sub-area, the upper right bucket blade opening processing sub-area, the lower right bucket blade opening processing sub-area, and the upper part of the water-dividing blade processing sub-area; 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.

[0017] 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; 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.

[0018] 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; 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.

[0019] Furthermore, 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.

[0020] Furthermore, in step 6, the auxiliary processing grooves include a water inlet groove, a cutting groove, a water-dividing blade groove, and a water-blade cavity groove; the water inlet groove and the water-dividing blade groove are open planes.

[0021] The water inlet process trough includes a left water inlet process trough and a right water inlet process trough. The left water inlet process trough includes an upper left water inlet process trough, a middle left water inlet process trough and a lower left water inlet process trough. The right water inlet process trough includes an upper right water inlet process trough, a middle right water inlet process trough and a lower right water inlet process trough.

[0022] The cutting groove process groove includes a left cutting groove process groove and a right cutting groove process groove;

[0023] The bucket blade cavity process groove includes the left bucket blade cavity process groove and the right bucket blade cavity process groove.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] This invention also provides a CNC forming method for large water bucket parts for impact turbines, implemented according to the above-mentioned design method, including the following steps:

[0029] S1: According to the designed clamping position, weld clamping blocks 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, clamp the water bucket forging on the floor boring machine according to the front position, and then process the auxiliary machining process groove according to the design.

[0030] S2: Follow the designed toolpath and perform machining in the order of the first machining area, the second machining area, and the third machining area;

[0031] S3: 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.

[0032] S4: The water bucket forging is clamped on the floor boring machine according to the cutting groove station in the back station, and processed in the fourth machining area according to the designed toolpath;

[0033] S5: 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 according to the designed toolpath;

[0034] S6: Mount the water bucket forging on the left side of the back side of the back side station on the floor boring machine and process it in the sixth machining area according to the designed toolpath;

[0035] S7: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine. It is then machined in the seventh machining area according to the designed toolpath to finally obtain the water bucket part.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] 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. It provides a good design template for the CNC machining of large water bucket parts for impact turbines.

[0038] 2. The design of the auxiliary machining process groove in this invention significantly increases the effective toolpath ratio, shortens machining time, extends the average tool replacement cycle, improves machining stability, and improves overall manufacturing efficiency. Attached Figure Description

[0039] Figure 1 A three-dimensional schematic diagram of the water bucket of an impulse turbine;

[0040] Figure 2 This is a three-dimensional schematic diagram of the water bucket component of the present invention;

[0041] Figure 3 for Figure 2 A 3D view of the left side of the water bucket component;

[0042] Figure 4 This is a three-dimensional schematic diagram of the water bucket forging of the present invention;

[0043] Figure 5 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;

[0044] Figure 6 This is a schematic diagram showing the centroid and clamping position of the front work station of the water bucket forging of the present invention;

[0045] Figure 7 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;

[0046] Figure 8 This is a schematic plan view of the first processing area of ​​the present invention;

[0047] Figure 9 This is a three-dimensional schematic diagram of the second processing area of ​​the present invention;

[0048] Figure 10 This is a schematic plan view of the second processing area of ​​the present invention;

[0049] Figure 11This is a three-dimensional schematic diagram of the third processing area of ​​the present invention;

[0050] Figure 12 This is a schematic plan view of the third processing area of ​​the present invention;

[0051] Figure 13 This is a schematic diagram of the fourth processing area of ​​the present invention;

[0052] Figure 14 This is a schematic diagram of the fifth processing area of ​​the present invention;

[0053] Figure 15 This is a schematic diagram of the sixth processing area of ​​the present invention;

[0054] Figure 16 This is a schematic diagram of the seventh processing area of ​​the present invention;

[0055] Figure 17 This is a schematic diagram of the auxiliary machining process groove on the front of the water bucket forging of the present invention;

[0056] Figure 18 for Figure 17 A side view of the stepped process tank;

[0057] Figure 19 This is a schematic diagram of the toolpath settings for the processing of each processing sub-region in the first processing area of ​​the present invention;

[0058] Figure 20 This is a schematic diagram of the toolpath setting during the machining process in the second machining area of ​​the present invention;

[0059] Figure 21 This is a schematic diagram of the toolpath setting in the third processing area of ​​the present invention;

[0060] Figure 22 This is a schematic diagram simulating the processing of the fourth processing area of ​​the present invention;

[0061] Figure 23 This is a schematic diagram simulating the processing of the fifth processing area of ​​the present invention;

[0062] Figure 24 This is a schematic diagram simulating the processing of the sixth and seventh processing areas of the present invention;

[0063] Figure 25 This is a schematic diagram of the tool trajectory for machining the bucket blade opening in the present invention (comparative example).

[0064] Figure 26 This is a schematic diagram of the tool trajectory for machining the bucket blade cavity in the present invention (comparative example).

[0065] 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; O - XYZ - Basic coordinate system in the 3D model of the water bucket part; o - xyz - Basic coordinate system in the 3D model of the water bucket forging; 280 - Center of mass position of the water bucket forging; 281 - Upper left clamping position of the bucket back of the water bucket forging; 282 - Upper right clamping position of the bucket back of the water bucket forging; 283 - Bucket forging bucket Lower left clamping position; 284 - Lower right clamping position of bucket back forging; 001 - First dividing plane; 002 - Second dividing plane; 1301 - Upper left bucket blade opening; 1302 - Lower left bucket blade opening; 1303 - Upper right bucket blade opening; 1304 - Lower right bucket blade opening; 1501 - Upper part of water-dividing blade; 1101 - Upper left part of bucket blade cavity; 1102 - Upper right part of bucket blade cavity; 1502 - Middle part of water-dividing blade; 1601 - Left cutting groove; 1602 - Right cutting groove; 1201 - Upper left of bucket back Part; 1202 - Upper right part of bucket back; 1103 - Lower left part of bucket blade cavity; 1104 - Lower right part of bucket blade cavity; 1503 - Lower part of water-dividing blade; 1603 - End face of cutting groove; 1203 - Groove on blade back; 1401 - End face of root groove; 1204 - Left side face of bucket back; 1205 - Right side face of bucket back; 230a - Process groove of upper left water bucket mouth; 230b - Process groove of middle left water bucket mouth; 230c - Process groove of lower left water bucket mouth; 230d - Process groove of upper right water bucket mouth; 230e - Process groove of middle right water bucket mouth Water inlet process groove; 230f - lower right water 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-dividing blade process groove; K - process groove machining width; 2X0 - inclined surface; 2X0x - process 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 process groove step in the transverse direction; h - height of the step; 300 - machining tool. Detailed Implementation

[0066] The following detailed description, in conjunction with specific embodiments, provides a method for the design and processing of CNC forming of large water bucket parts for impulse turbines. These embodiments are for illustrative purposes only, and the present invention is not limited to these embodiments.

[0067] The impact turbine water bucket of the present invention has a maximum size of more than 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.

[0068] 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 design method for large water bucket components used in impact turbines, comprising the following steps:

[0069] Step 1: Enable the CAD function of the software and create a 3D model of the water bucket parts;

[0070] Step 2: Machining a rough datum for the water bucket forging, then performing 3D scanning and outputting the 3D model of the water bucket forging into the CAD function of the software;

[0071] Step 3: Adjust the pose of the 3D model of the water bucket forging so that the 3D model of the water bucket part is contained within the 3D model of the water bucket forging. Record the translation and rotation values ​​of the 3D model of the water bucket forging relative to the 3D model of the water bucket part. Then, make a new finishing datum on the allowance according to the rough datum in Step 2.

[0072] Step 4: Based on the centroid position and finishing datum of the 3D model of the water bucket forging, design the clamping position for machining the front of the water bucket forging.

[0073] Step 5: Based on the shape and size characteristics of each part of the water bucket parts and water bucket forgings, design and divide the workstations and processing areas for full surface machining;

[0074] Step 6: Design auxiliary machining process grooves according to the machining area corresponding to the front station of the water bucket forging;

[0075] Step 7: Enable the CAM function in the software, select the cavity milling mode, set the machining toolpaths in each machining area of ​​the 3D model of the water bucket forging, generate the machining toolpath code, and generate the CNC program after post-processing.

[0076] In step 2, the method for machining the rough datum of the water bucket forging is as follows: a horizontal datum surface of 50mm × 50mm is machined on both sides of the allowance above the bucket blade opening, and an angular datum surface of 50mm × 50mm is machined on both sides of the allowance in front of the root groove. The function of the datum surface is to obtain the workpiece posture determined by this datum after 3D scanning.

[0077] After machining the rough datum of the water bucket forging using a gantry milling machine, the entire water bucket forging is scanned using a 3D scanner. During the scanning process, the position of the rough datum needs to be accurately recorded, and the 3D model of the water bucket forging with the rough datum is imported into CAD software.

[0078] In step 3, 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 with a coarse datum. First, the two coordinate systems are aligned, and then the position of the 3D model of the water bucket forging is adjusted. When the 3D model of the water bucket part is completely contained within the 3D model of the water bucket forging, the spatial translation and rotation values ​​of the basic coordinate system o-xyz of the 3D model of the water bucket forging relative to the basic coordinate system O-XYZ of the 3D model of the water bucket part are recorded. The adjustment process includes six degrees of freedom: translation and rotation. Figure 5 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.

[0079] Specifically, in step 4, the centroid position of the 3D model of the water bucket blank is determined using 3D modeling software, such as UG. Based on the centroid position of the water bucket, four clamping positions (upper left, upper right, lower left, and lower right) are designed on the back side of the water bucket forging, so that the water bucket forging can be machined in the front position facing the boring machine spindle. Figure 6 This is a schematic diagram of the centroid and clamping position of the front station of the water bucket forging of the present invention. The centroid is 280, the upper left clamping position is 281, the upper right clamping position is 282, the lower left clamping position is 283, and the lower right clamping position is 284.

[0080] In step 5, the water bucket forging is divided into a front station and a back station. The corresponding machining portion of the front station is divided into three machining areas by two horizontal cross-sections from top to bottom. The first machining area includes the machining area of ​​the bucket blade opening and the upper part of the water-dividing blade. The second machining area includes the machining area of ​​the upper part of the bucket blade cavity and the middle part of the water-dividing blade, or the machining 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 machining area includes the machining area of ​​the lower part of the bucket blade cavity and the lower part of the water-dividing blade. The back station is divided into a cutting groove station, a root groove station, a back left side station, and a back right side station. The machining portion 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. The machining portion corresponding to the root groove station is the fifth machining area, which includes the root groove end face machining area. The back left side station corresponds to the sixth machining area, which includes the bucket back left side machining area. The back right side station corresponds to the seventh machining area, which includes the bucket back right side machining area.

[0081] During processing, starting from the first processing area, the second, third, fourth, fifth, and sixth processing areas are processed sequentially until the seventh processing area is completed, thus completing the full surface processing of the water bucket forging and obtaining the water bucket part.

[0082] 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.

[0083] 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. Figure 1 Figure a in the middle or Figure 2 As shown; the opposite back position refers to the position where the bucket blade opening 130 is placed downwards and the bucket back 120 faces the Z-axis of the machine tool spindle, as shown. Figure 1 As shown in Figure b.

[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 7 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 8This is a schematic plan view of the first processing area of ​​the present invention. This processing area includes five sub-processing areas: the upper left bucket blade inlet 1301, the lower left bucket blade inlet 1302, the upper right bucket blade inlet 1303, the lower right bucket blade inlet 1304, and the upper part of the water-dividing blade 1501. The lower second dividing plane 002 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 constitutes the second processing area. Figure 9 This is a three-dimensional schematic diagram of the second processing area of ​​the present invention. Figure 10 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 the left side 1204 of the bucket back in the sixth processing area, and the upper right part 1202 of the bucket back belongs to the right side 1205 of the bucket back in the seventh processing area. Figure 9 and Figure 10 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 subsequent fourth processing area, the entire cutting groove processing is finally completed.

[0085] The area below the second dividing plane 002 is the third processing area. Figure 11 This is a three-dimensional schematic diagram of the third processing area of ​​the present invention. Figure 12 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.

[0086] Specifically, 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; the root groove 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; the left side back-side workstation refers to the station where the left side of the water tank back faces the Z-axis of the machine tool spindle when the water tank is placed on the back; and the right side back-side workstation refers to the station where the right side of the water tank back faces the Z-axis of the machine tool spindle when the water tank is placed on the back.

[0087] The cutting groove station corresponds to the fourth processing area. Figure 13 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. The processing portion corresponding to the root groove station is the fifth processing area. Figure 14 This is a schematic diagram of the fifth processing area of ​​the present invention, which includes the root groove end face 1401. The processing portion corresponding to the workstation on the left side of the back is the sixth processing area. Figure 15 This is a schematic diagram of the sixth processing area of ​​the present invention, which includes the left side of the bucket back 1204. The processing portion corresponding to the workstation on the right side of the back is the seventh processing area. Figure 16 This is a schematic diagram of the seventh processing area of ​​the present invention, which includes the right side 1205 of the bucket back.

[0088] In step 6, Figure 17 This 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 17 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.

[0089] 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.

[0090] The left middle water bucket inlet process groove 230b, the right middle water bucket inlet process groove 230e, the left cutting groove process groove 260a, and the right cutting groove process groove 260b divide the water bucket inlet and the water dividing blade into five independent processing sub-areas, namely the left upper bucket blade inlet processing sub-area, the left lower bucket blade inlet processing sub-area, the right upper bucket blade inlet processing sub-area, the right lower bucket blade inlet processing sub-area, and the upper part of the water dividing blade processing sub-area of ​​the first processing area. When machining the upper left and lower left bucket blade areas, the cutter head needs to rotate from the middle left bucket blade process groove 230b; when machining the upper right and lower right bucket blade areas, the cutter head needs to rotate from the middle right bucket blade process groove 230e. Therefore, the machining width K of the middle left bucket blade process groove 230b and the middle right bucket blade process groove 230e is greater than the diameter of the cutter head. In other words, the distance between the upper and lower bucket blade openings of the bucket part determines the diameter of the cutter head. That is, the diameter of the cutter head cannot be greater than the distance between the upper and lower bucket blade openings of the bucket part. For example, if the distance between the upper and lower bucket blade openings of the bucket part is 250mm, the cutter head is D200R8. The cutting groove process slot is set up, and the machining width K of the cutting groove process slot is greater than the diameter of the machining cutter head. In other words, the machining width K of the cutting groove process slot 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 slot. For example, if the machining width K of the cutting groove process slot is 250mm, the machining cutter head is D200R8. The purpose is to ensure that when machining the lower bucket blade opening and the water-dividing blade, the cutter head can rotate around from the cutting groove process slot. That is, when machining the lower left bucket blade opening, the cutter head rotates around from the left cutting groove process slot; when machining the lower right bucket blade opening, the cutter head rotates around from the right cutting groove process slot; when machining the water-dividing blade, the cutter head rotates around from both the left and right cutting groove process slots.

[0091] 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.

[0092] Specifically, Figure 18 for Figure 17 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.

[0093] 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, 10mm≤M≤20mm can be specified. It should be noted that limiting the maximum value of K+M aims to ensure that the machining head can rotate through the process groove according to the toolpath design, preventing tool damage from tool embedding when machining the top surface of the water-dividing blade, the top surface of the water-dividing 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 machining, improving machining efficiency; limiting the minimum value of M aims to improve the surface quality of the formed workpiece and appropriately reduce the workload of machining the process groove.

[0094] 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.

[0095] 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), and the symbol should be consistent. 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 The maximum depth of the process tank step in the transverse direction is represented by the symbol; 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.

[0096] In step 7, the five processing sub-regions of the first processing area—the upper left bucket blade inlet 1301 processing sub-region, the lower left bucket blade inlet 1302 processing sub-region, the upper right bucket blade inlet 1303 processing sub-region, the lower right bucket blade inlet 1304 processing sub-region, and the upper part of the water-dividing blade 1501 processing sub-region—are processed independently. Figure 19This diagram illustrates the toolpath settings for each sub-region of the first processing area in this invention. As can be seen, the toolpath for each independent region is clear, with the tool entry and exit positions all located in safe positions outside the workpiece. This results in high cutting efficiency, eliminates inefficient and useless toolpaths such as idle tool transfer, and facilitates operator observation during actual processing, reducing the probability of human error.

[0097] Figure 20 This is a schematic diagram of the toolpath setting for the second processing area of ​​the present invention. Figure D shows the toolpath setting 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 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 setting 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.

[0098] Figure 21 This is a schematic diagram of the toolpath setup for the third processing area of ​​the present invention. Figures A to C represent the toolpath diagrams for each stage of the processing. 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.

[0099] Figure 22 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.

[0100] Figure 23This 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.

[0101] 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.

[0102] Secondly, based on the above design method, this invention also proposes a CNC forming method for large water bucket parts for impact turbines, comprising the following steps:

[0103] S1: According to the designed clamping position, weld clamping blocks 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, clamp the water bucket forging on the floor boring machine according to the front position, and then process the auxiliary machining process groove according to the design.

[0104] S2: Follow the designed toolpath and perform machining in the order of the first machining area, the second machining area, and the third machining area;

[0105] S3: 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.

[0106] S4: The water bucket forging is clamped on the floor boring machine according to the cutting groove station in the back station, and processed in the fourth machining area according to the designed toolpath;

[0107] S5: 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 according to the designed toolpath;

[0108] S6: Mount the water bucket forging on the left side of the back side of the back side station on the floor boring machine and process it in the sixth machining area according to the designed toolpath;

[0109] S7: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine. It is then machined in the seventh machining area according to the designed toolpath to finally obtain the water bucket part.

[0110] In step S1, the water bucket forging is adjusted by the spatial translation and rotation values ​​of the basic coordinate system o-xyz of the three-dimensional model of the water bucket forging relative to the basic coordinate system O-XYZ of the three-dimensional model of the water bucket part, so that it is clamped on the floor boring machine in the front position.

[0111] In steps S6 and S7, 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.

[0112] The design and processing method of this invention shorten processing time and improve processing efficiency and stability.

[0113] Example

[0114] 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.

[0115] 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.

[0116] A CNC forming design method for large water bucket parts for impulse turbines includes the following steps:

[0117] Step 1: Enable the CAD function of the software and create a 3D model of the water bucket parts;

[0118] Step 2: Machining a rough datum for the water bucket forging, then performing 3D scanning and outputting the 3D model of the water bucket forging into the CAD function of the software;

[0119] The method for machining the rough datum of the water bucket forging is to machine a horizontal datum surface of 50mm×50mm on both sides of the allowance above the bucket blade opening, and an angular datum surface of 50mm×50mm on both sides of the allowance in front of the root groove.

[0120] Step 3: Adjust the pose of the 3D model of the water bucket forging so that the 3D model of the water bucket part is contained within the 3D model of the water bucket forging. Compare the actual workpiece pose required when adjusting the 3D model in the software, and determine the spatial translation values ​​X = -3.2mm, Y = 1.4mm, Z = -5mm and the rotation values ​​Rx = 0.5°, Ry = -0.6° between the two poses. Maintain this pose of the 3D model of the water bucket forging, and re-establish the finishing datum based on the rough datum plane sizes in Step 2, within the allowance.

[0121] Step 4: Based on the centroid position and finishing datum of the 3D model of the water bucket forging, design the clamping position for machining the front of the water bucket forging.

[0122] The centroid position of the 3D model of the water bucket forging was determined using UG drawing software. Based on the centroid position of the water bucket, four clamping positions (upper left, upper right, lower left, and lower right) were designed on the back side of the water bucket forging. The lower left and lower right clamping blocks were symmetrical about the workpiece's central axis, with a spacing of 600mm, and the lowest point of the water bucket forging was 350mm above the machine tool bed surface. The upper left and upper right clamping blocks were symmetrical about the workpiece's central axis, with a spacing of 1300mm, and 600mm away from the lowest point of the water bucket forging, so that the water bucket forging could be machined directly facing the boring machine spindle in the front working position.

[0123] Step 5: Based on the shape and size characteristics of each part of the water bucket parts and water bucket forgings, design and divide the workstations and processing areas for full surface machining;

[0124] The water bucket forging is divided into a front station and a back station. The corresponding machining part of the front station is divided into three machining areas by two horizontal cross sections from top to bottom. The first machining area includes the machining area of ​​the bucket blade opening and the upper part of the water-dividing blade. The second machining area includes the machining area of ​​the upper part of the bucket blade cavity and the middle part of the water-dividing blade, or the machining 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 machining area includes the machining area of ​​the lower part of the bucket blade cavity and the lower part of the water-dividing blade. The back station is divided into a cutting groove station, a root groove station, a back left side station, and a back right side station. 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. The machining part corresponding to the root groove station is the fifth machining area, which includes the machining area of ​​the root groove end face. The back left side station corresponds to the sixth machining area, which includes the machining area of ​​the left side of the bucket back. The back right side station corresponds to the seventh machining area, which includes the machining area of ​​the right side of the bucket back.

[0125] 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 upper 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 area above the first dividing plane is the first machining area, which includes five sub-machining areas: 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. The lower second dividing plane is determined by the lowest point of the cutting groove, 200mm away from the first dividing plane. The area between the first and second dividing planes is the second machining area, which includes 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 cutting, and the right cutting groove cutting.

[0126] 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 part of the water-dividing blade.

[0127] Specifically, 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; the root groove 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; the left side back-side workstation refers to the station where the left side of the water tank back faces the Z-axis of the machine tool spindle when the water tank is placed on the back; and the right side back-side workstation refers to the station where the right side of the water tank back faces the Z-axis of the machine tool spindle when the water tank is placed on the back.

[0128] The cutting groove station corresponds to the fourth processing area, which includes the cutting groove end face and the blade back groove. The root groove station corresponds to the fifth processing area, which includes the root groove end face. The back left side station corresponds to the sixth processing area, which includes the left side of the bucket back. The back right side station corresponds to the seventh processing area, which includes the right side of the bucket back.

[0129] Step 6: Design auxiliary machining process grooves according to the machining area corresponding to the front station of the water bucket forging;

[0130] 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.

[0131] 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 are each composed of an independent plane. 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 process groove consists of two U-shaped opening grooves, including the left and right cutting groove process 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 process groove is on the plane where the lowest point of the bucket blade inlet is located, with a width of 250mm.

[0132] The left and right middle water inlet process channels, the left cutting channel process channel, and the right cutting channel process channel divide the water inlet and the water-dividing blade into five independent processing sub-areas, namely 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 of ​​the first processing area. When machining the upper left and lower left bucket blade inlet sub-areas, the cutter head needs to rotate back and forth from the middle left bucket inlet process groove; when machining the upper right and lower right bucket blade inlet sub-areas, the cutter head needs to rotate back and forth from the middle right bucket inlet process groove. Therefore, the machining width K of the middle left and middle right bucket inlet process grooves is greater than the diameter of the cutter head. In other words, the distance between the upper and lower bucket inlets of the bucket part determines the diameter of the cutter head. That is, the diameter of the cutter head cannot be greater than the distance between the upper and lower bucket inlets of the bucket part. The distance between the upper and lower bucket inlets of the bucket part is 250mm, and the cutter head is D200R8. The cutting groove process slot is set up, and the machining width K of the cutting groove process slot is greater than the diameter of the machining cutter head. In other words, the machining width K of the cutting groove process slot 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 slot. The machining width K of the cutting groove process slot is 250mm, and the machining cutter head is D200R8. The purpose is to enable the cutter head to rotate and move around in the cutting groove process slot when machining the lower bucket blade opening and the water-dividing blade. That is, when machining the lower left bucket blade opening, the cutter head rotates and moves around in the left cutting groove process slot; when machining the lower right bucket blade opening, the cutter head rotates and moves around in the right cutting groove process slot; when machining the water-dividing blade, the cutter head rotates and moves around in the left and right cutting groove process slots.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] Step 7: Enable the CAM function of the software, select the cavity milling mode, set the machining toolpaths in each machining area of ​​the 3D model of the water bucket forging, generate the machining toolpath code, and generate the CNC program after post-processing.

[0139] The five processing sub-areas of the first processing area are processed independently. Figure 19 This is a schematic diagram of the toolpath settings for the processing of each sub-region of the first processing area in this embodiment. Figure 20 Figure D is a schematic diagram of the toolpath setting in the second processing area of ​​this embodiment. Figure 21 This is a schematic diagram of the toolpath setting in the third processing area of ​​this embodiment. Figures A to C represent the toolpath schematic diagrams at each stage of the processing.

[0140] Figure 22 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.

[0141] Figure 23This 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.

[0142] 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.

[0143] Based on the above design method, a CNC forming machining method for large water bucket parts for impact turbines includes the following steps:

[0144] S1: According to the designed clamping position, weld clamping blocks 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, clamp the water bucket forging on the floor boring machine according to the front position, and then process the auxiliary machining process groove according to the design.

[0145] The water bucket forging is adjusted by using the spatial translation and rotation values ​​of the basic coordinate system o-xyz of the three-dimensional model of the water bucket forging relative to the basic coordinate system O-XYZ of the three-dimensional model of the water bucket part, so that it can be clamped on the floor boring machine in the front position.

[0146] S2: Follow the designed toolpath and perform machining in the order of the first machining area, the second machining area, and the third machining area;

[0147] S3: 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.

[0148] S4: The water bucket forging is clamped on the floor boring machine according to the cutting groove station in the back station, and processed in the fourth machining area according to the designed toolpath;

[0149] S5: 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 according to the designed toolpath;

[0150] S6: Mount the water bucket forging on the left side of the back side of the back side station on the floor boring machine and process it in the sixth machining area according to the designed toolpath;

[0151] S7: The water bucket forging is clamped on the right side of the back side of the back side station on the floor boring machine. It is then machined in the seventh machining area according to the designed toolpath to finally obtain the water bucket part.

[0152] In steps S6 and S7, 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.

[0153] The manufacturing efficiency of this embodiment is shown in Table 1.

[0154] Comparative Example

[0155] This comparative example follows conventional machining processes, using a gantry milling machine to perform full-surface machining on the water bucket forging. No specific machining zones or machining grooves are designed; 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 part of the cutting groove), and the upper part of the bucket back (including the remaining cutting groove). The machining steps are as follows:

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] The manufacturing efficiency of the comparative model is shown in Table 1.

[0162] Will Figure 19 , Figure 20 (D) Figure 21 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.

[0163] Table 1 Manufacturing efficiency of the examples and comparative examples

[0164]

[0165] 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.

[0166] 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 method for numerically controlled forming design of a large bucket part for a Pelton turbine, characterized by, The maximum size of the large bucket part is more than 1 meter; the method comprises the following steps: Step 1: enable the software CAD function to establish a three-dimensional model of the bucket part; Step 2: process a rough reference for the bucket forging, then perform 3D scanning and output the three-dimensional model of the bucket forging to the software CAD function; Step 3: adjust the pose of the three-dimensional model of the bucket forging, so that the three-dimensional model of the bucket part is contained in the three-dimensional model of the bucket forging, record the translation value and rotation value of the three-dimensional model of the bucket forging relative to the three-dimensional model of the bucket part, and re-roughen the fine machining reference on the margin according to the rough reference in step 2; Step 4: according to the centroid position of the three-dimensional model of the bucket forging and the fine machining reference, design the clamping position of the bucket forging when the front position is machined; Step 5: according to the shape and size characteristics of each part of the bucket part and the bucket forging, design the position and each machining area of the full-surface machining; Step 6: according to the machining area corresponding to the front position of the bucket forging, design the auxiliary machining process groove; Step 7: enable the software CAM function, select the cavity milling mode, set the machining tool path in each machining area of the three-dimensional model of the bucket forging, generate the machining tool path code, and generate the numerical control program after post-processing.

2. The method of claim 1, wherein, In step 5, the position includes a front position and a back position; the front position corresponds to a first machining area, a second machining area and a third machining area; the back position corresponds to a fourth machining area, a fifth machining area, a sixth machining area and a seventh machining area.

3. The method of claim 2, wherein, The first machining area is located above the first division plane and includes a left upper bucket blade opening machining sub-area, a left lower bucket blade opening machining sub-area, a right upper bucket blade opening machining sub-area, a right lower bucket blade opening machining sub-area and a water distribution blade upper machining sub-area; the first division plane is perpendicular to the machine tool spindle Z axis and is determined by the highest point of the bucket blade cavity.

4. The method of claim 2, wherein, The second machining area is located between the first division plane and the second division plane and includes a bucket blade cavity left upper part, a bucket blade cavity right upper part and a water distribution blade middle part, a left cutting groove reduction and a right cutting groove reduction, or a bucket blade cavity left upper part, a bucket blade cavity right upper part, a water distribution blade middle part, a left cutting groove reduction, a right cutting groove reduction and a bucket back left upper part and a bucket back right upper part; the first division plane is perpendicular to the machine tool spindle Z axis and is determined by the highest point of the bucket blade cavity; the second division plane is perpendicular to the machine tool spindle Z axis and is determined by the lowest point of the cutting groove.

5. The method of claim 2, wherein, The third machining area is located below the second division plane and includes a bucket blade cavity left lower part, a bucket blade cavity right lower part and a water distribution blade lower part; the second division plane is perpendicular to the machine tool spindle Z axis and is determined by the lowest point of the cutting groove.

6. The method of claim 2, wherein, The fourth machining area includes a cutting groove end face and a blade back groove; the fifth machining area includes a root groove end face; the sixth machining area includes a bucket back left side face; and the seventh machining area includes a bucket back right side face.

7. The method of claim 1 wherein, In step 6, the auxiliary machining process groove includes a bucket mouth process groove, a cutting groove process groove, a water distribution blade process groove and a bucket blade cavity process groove; the bucket mouth process groove and the water distribution blade process groove are open planes. The water bucket mouth process tank comprises a left water bucket mouth process tank and a right water bucket mouth process tank, wherein the left water bucket mouth process tank comprises an upper left water bucket mouth process tank, a middle left water bucket mouth process tank and a lower left water bucket mouth process tank, and the right water bucket mouth process tank comprises an upper right water bucket mouth process tank, a middle right water bucket mouth process tank and a lower right water bucket mouth process tank; The cutting groove process tank comprises a left cutting groove process tank and a right cutting groove process tank; The bucket blade cavity process tank comprises a left bucket blade cavity process tank and a right bucket blade cavity process tank.

8. The method of claim 7, wherein, The middle left water bucket mouth process tank and the middle right water bucket mouth process tank are respectively composed of an open plane, the middle left water bucket mouth process tank and the middle right water bucket mouth process tank are on the same plane with the highest point of the bucket blade cavity, the processing width of the middle left water bucket mouth process tank and the middle right water bucket mouth process tank is equivalent to the interval between the upper water bucket mouth and the lower water bucket mouth of the finally formed water bucket part, and is greater than the diameter of the processing cutter head; The left cutting groove process tank and the right cutting groove process tank are two U-shaped open grooves, the bottom surface of the U-shaped open groove is perpendicular to the Z-axis of the machine tool main shaft, the processing depth of the U-shaped open groove is consistent with the plane where the lowest point of the processed bucket blade mouth is located, and the processing width of the U-shaped open groove is greater than the diameter of the processing cutter head; The upper left water bucket mouth process tank, the lower left water bucket mouth process tank, the upper right water bucket mouth process tank, the lower right water bucket mouth process tank, the water distribution blade process tank, the left bucket blade cavity process tank and the right bucket blade cavity process tank are respectively composed of a plurality of continuous step-shaped planes perpendicular to the Z-axis of the machine tool main shaft, the inclines of the plurality of steps are respectively consistent with the shapes of the water bucket mouth, the water distribution blade and the bucket blade cavity of the finally formed water bucket part, and the step plane corresponding to the highest point of the water bucket mouth and the water distribution blade is processed to the finally formed water bucket part body.

9. The method of claim 8, wherein, The sum of the step processing width and the step depth in the transverse direction of the upper left water bucket mouth process tank, the lower left water bucket mouth process tank, the upper right water bucket mouth process tank, the lower right water bucket mouth process tank and the water distribution blade process tank satisfies 0.8d≤K+M≤d; the sum of the step processing width and the step depth in the transverse direction of the left bucket blade cavity process tank and the right bucket blade cavity process tank satisfies 0.6d≤K+M≤d; in the formula, d represents the diameter of the processing cutter head, K represents the processing width of the process tank step, and M represents the depth in the transverse direction of the process tank step, 10mm≤M≤20mm.

10. A numerical control forming machining method for a large water bucket part for a Pelton turbine, characterized by, The processing method is implemented according to any one of the methods in claims 1-9, and the processing method comprises the following steps: S1: welding clamping blocks on the water bucket forging according to the designed clamping position, using a pad to pad on the right lower and left lower clamping blocks, using a pressing plate to press on the right upper and left upper clamping blocks, clamping the water bucket forging on the floor boring machine according to the front position, and then processing the auxiliary process tank according to the design; S2: processing in the order of the first processing area, the second processing area and the third processing area according to the designed tool path; S3: after the front position processing is completed, the bucket blade cavity is opposite to the workbench, the water distribution blade is higher than the workbench by using an adjustable pad iron to pad the water bucket mouth, the upper part of the right upper and left upper clamping blocks in step S1 is pressed by the pressing plate, and the water bucket forging is clamped on the floor boring machine according to the back position. S4: the water bucket forge piece is clamped on the floor boring machine according to the cutting groove position in the back position, and the fourth machining area is machined according to the designed tool path; S5: the water bucket forge piece is clamped on the floor boring machine according to the root groove position in the back position, and the fifth machining area is machined according to the designed tool path; S6: the water bucket forge piece is clamped on the floor boring machine according to the back left side position in the back position, and the sixth machining area is machined according to the designed tool path; S7: the water bucket forge piece is clamped on the floor boring machine according to the back right side position in the back position, and the seventh machining area is machined according to the designed tool path, and finally the water bucket part is obtained.

Images