Dovetail blade root blade machining method

Abstract

The invention discloses a dovetail blade root blade machining method, relates to the technical field of turbine blade machining, and aims to solve the problems that an existing blade forging blank structure is not suitable for clamping, a blade machining method selects sequential machining, the datum conversion in the machining process is more, and the machining precision is unstable. The number of tools is large, and the tool cost is high; the method comprises the following steps that firstly, a three-axis vertical milling machine is adopted for machining, a blade root end ejector pin of a machine tool abuts against two blade root side ejector pin holes of a blade blank, a blade crown end ejector pin abuts against a blade crown ejector pin hole, clamping of the blade blank is completed, and the blade root side ejector pin hole and the blade crown side ejector pin hole are formed; the blade root process clamping handle and the blade crown process clamping handle are machined through a milling cutter with the diameter being 20-25 and embedded with hard alloy pieces; and secondly, a four-axis milling machine is adopted for machining, a blade root end ejector pin of a machine tool abuts against a blade root center ejector pin hole of the blade blank, and the dovetail blade root machining method is used for dovetail blade root machining.

Description

Technical Field

[0001] This invention relates to the field of turbine blade processing technology, and in particular to a method for processing dovetail blade roots. Background Technology

[0002] A gas turbine is a power machine that uses continuous combustion to generate high-temperature, high-pressure gas to drive a turbine. Its core structure consists of three parts: a compressor, a combustion chamber, and a power turbine. During operation, the compressor draws in air, pressurizes it, and sends it into the combustion chamber, where it mixes and burns with injected fuel to form high-temperature gas. This gas then expands and impacts the turbine blades at high speed, driving the turbine to rotate at high speed and output mechanical work. Gas turbines are characterized by high power density, rapid start-up, and low vibration, but their manufacturing process is complex and requires extremely high-temperature resistant materials, making them key equipment in the energy, transportation, and defense sectors. Gas turbine compressors often employ dovetail-root, crownless blade structures. The blade materials are often made of difficult-to-machine titanium alloys and other high-temperature alloys. To control the machining allowance of the blades, the blade blanks are forged.

[0003] However, the blank structure of the blade forging in the past was not suitable for clamping, and the blade processing method was also to select sequential processing. The processing process involved many reference conversions, resulting in unstable processing accuracy; the number of tooling was large, and the tooling cost was high; the waiting between each process in sequential processing and the multiple clamping resulted in excessively long processing cycles. Summary of the Invention

[0004] In order to solve the problems mentioned in the background art, the present invention provides a method for processing swallowtail blade roots to solve the problems mentioned above. These problems include the unsuitability of the blank structure of existing blade forging forging for clamping, the selection of sequential processing methods for blade processing, the large number of reference transformations in the processing process, the high cost of tooling, and the excessively long processing cycle caused by waiting between each process and multiple clamping.

[0005] The technical solution of this invention is:

[0006] A method for processing swallowtail leaf roots and leaves, the method comprising the following steps:

[0007] Step 1: Using a three-axis vertical milling machine, clamp the blade root end ejector pins to the two blade root side ejector pin holes of the blade blank, and clamp the blade crown end ejector pins to the blade crown ejector pin holes to complete the clamping of the blade blank. Use a φ20-25 carbide-insulated milling cutter to process the blade root process chuck and the blade crown process chuck.

[0008] Step 2: Using a four-axis milling machine, the blade root end ejector pin is pressed against the center ejector pin hole of the blade blank, the blade crown end ejector pin is pressed against the crown ejector pin hole, and the blade root process chuck is clamped with a jaw clamp to complete the clamping of the blade blank. The blade blank is then rough-machined using a φ40 end mill with an R6 high-cutting-edge insert.

[0009] Step 3: Use a five-axis linkage CNC machining center for precision machining. Tighten the blade root end pin to the center pin hole of the blade blank, and tighten the crown end pin to the crown pin hole. Clamp the blade root process chuck and the crown process chuck with two jaws to complete the clamping of the blade blank. Use the end cutting edge of a φ20 solid carbide end mill to machine the dovetail surface of the dovetail blade root. After completing the dovetail surface machining, rotate the spindle 60 degrees and use the end cutting edge to machine the quasi-dovetail chamfer surface. Then, with the tool spindle perpendicular to the blade centerline, use the side cutting edge of the tool to machine the end face of the dovetail blade root.

[0010] Step 4: Wire cut the blade crown end face;

[0011] Step 5: Wire cut the leaf root end face;

[0012] Step 6: Grind the blade root end face. Place the blade vertically with the blade root facing upwards, clamp the blade root with a blade root clamp, and grind the blade root end face using a horizontal spindle surface grinder.

[0013] Furthermore, in step one, when machining the leaf root process clamp and the leaf crown process clamp, the roughing depth is 0.5-0.7mm, the machine tool speed is 60-100r / min, and the feed is 30mm / min for one cut; the finishing depth is 0-0.1mm, the machine tool speed is 60-100r / min, and the feed is 100mm / min for one cut.

[0014] Furthermore, in step two, during roughing, the cutting depth is 1mm, the machine tool speed is 636r / min, and the feed rate is 250mm / min;

[0015] Set the milling allowance as follows: 0.5mm for the dovetail surface of the blade root, 0.5mm for the large surface of the air intake side of the blade root, 0.7mm for the air passage, and 0.5-1mm for the remaining surfaces.

[0016] Furthermore, step three, finishing, consists of two steps: semi-finishing and finishing. The semi-finishing depth of cut is 0.1-0.2 mm, the machine tool speed is 1200 r / min, and the feed is 100 mm / min. The finishing depth of cut is 0-0.1 mm, the machine tool speed is 1200 r / min, and the feed is 100 mm / min.

[0017] Furthermore, the perpendicularity of the blade root end face to the intake side is 0.3, and the wire EDM is 0-0.5mm higher than the five-axis machining surface;

[0018] The cutting parameters are: pulse width 48μs, current 2A, voltage 90V, wire feed speed 60mm² / min.

[0019] Furthermore, step six involves grinding the blade root end face, which consists of two steps: semi-finishing and finishing. The roughing cutting parameters are a depth of cut of 0.02 mm, a rotation speed of 1440 r / min, and a feed rate of 140-150 mm / s. The finishing parameters are a depth of cut of 0.01 mm, a rotation speed of 1440 r / min, and a feed rate of 140-150 mm / s.

[0020] Furthermore, the blade blank includes the blade, the leaf root process clamp, and the leaf crown process clamp;

[0021] The blade root end is machined with a blade root process clamp, the blade crown end is machined with a blade crown process clamp, the connection between the blade root process clamp and the blade is machined with a hollow groove, and the connection between the blade crown process clamp and the blade is machined with a retraction extension section.

[0022] Furthermore, a leaf root center pin hole is provided at the center of the end face of the leaf root process clamp, and leaf root side pin holes are provided on both sides of the leaf root center pin hole. A leaf crown pin hole is provided at the center of the end face of the leaf crown process clamp.

[0023] Furthermore, the central pinhole at the leaf root and the pinhole at the leaf crown are coaxially arranged.

[0024] Furthermore, two leaf root side pin holes are symmetrically arranged along the center line of the leaf.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. A method for processing swallowtail blade roots, which optimizes the structure of the blade forging blank, designs a blade root process clamp and a blade crown process clamp, and opens a blade root center ejector hole at the center of the end face of the blade root process clamp, opens blade root side ejector holes on both sides of the blade root center ejector hole, and opens a blade crown ejector hole at the center of the end face of the blade crown process clamp. This reduces the reference conversion in the processing process, makes the relative positional relationship between the processed blade root profile and the steam passage more accurate, and reduces the number of tooling designs, thus lowering tooling costs.

[0027] 2. The design of using general-purpose carbide bar cutters instead of dedicated milling cutters is adopted. Five-axis linkage equipment is used to integrate the machining of blade passages and blade root profiles, which improves the machining accuracy of blades, reduces the design of dedicated blade root milling cutters, and greatly reduces the cost and cycle of blade machining. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the blade blank structure;

[0029] Figure 2 This is a schematic diagram of the pin hole structure;

[0030] Figure 3 This is a schematic diagram of the five-axis machining process;

[0031] Figure 4 This is a schematic diagram of a carbide end mill.

[0032] In the diagram: 1. Blade; 2. Blade root process clamp; 3. Blade crown process clamp; 4. Empty tool groove; 5. Retracting tool extension section; 6. Blade root center pin hole; 7. Blade root side pin hole; 8. Blade crown pin hole. Detailed Implementation

[0033] Specific implementation method one: See Figure 1-4 As shown, a method for processing swallowtail leaf roots and leaves includes the following steps:

[0034] Step 1: Using a three-axis vertical milling machine, the blade root end ejector pin is clamped to the two blade root side ejector pin holes 7 of the blade blank, and the blade crown end ejector pin is clamped to the blade crown ejector pin hole 8 to complete the clamping of the blade blank. The blade root process shank 2 and the blade crown process shank 3 are machined using a φ20-25 carbide inlaid milling cutter.

[0035] Step 2: Using a four-axis milling machine, the blade root end ejector pin is pressed against the center ejector pin hole 6 of the blade blank, and the blade crown end ejector pin is pressed against the crown ejector pin hole 8. The blade root process chuck 2 is clamped with a jaw clamp to complete the clamping of the blade blank. The blade 1 is rough machined using a φ40 end mill with an R6 high cutting edge insert.

[0036] Step 3: Use a five-axis linkage CNC machining center for precision machining. Tighten the blade root end pin to the blade blank's blade root center pin hole 6, and the blade crown end pin to the blade crown pin hole 8. Clamp the blade root process chuck 2 and the blade crown process chuck 3 with two jaws to complete the clamping of the blade blank. Use the end cutting edge of a φ20 solid carbide end mill to machine the dovetail surface of the dovetail blade root. After completing the dovetail surface machining, rotate the spindle 60 degrees and use the end cutting edge to machine the quasi-dovetail chamfer surface. Then, with the tool spindle perpendicular to the center line of blade 1, use the side cutting edge of the tool to machine the dovetail blade root end face.

[0037] Step 4: Wire cut the blade crown end face;

[0038] Step 5: Wire cut the leaf root end face;

[0039] Step 6: Grind the blade root end face. Place the blade root of blade 1 vertically upward, clamp the blade root with a blade root clamp, and grind the blade root end face using a horizontal axis surface grinder.

[0040] Furthermore, in Step 1, an XK715C non-lifting workbench CNC vertical milling machine is used for machining. During machining, ensure that the minimum allowance on both sides of the blade root process handle 2 is machined out to be ≥29, and the parallelism is ≤0.1, to avoid gaps between the clamp jaws and the handle during subsequent clamp jaw clamping, which may lead to failure to clamp. In Step 3, during the machining of this process, a 0.2 mm allowance is set on the blade root end face according to the product drawing. Among them, 0.15 is the assembly allowance, and 0.05 is the allowance for subsequent fine grinding of the blade root end face. After completing the machining in Step 3, the blade root profile and end face allowance are detected using an angle template. The template is designed with an end face allowance of 0.6 mm. During detection, when the two inclined surfaces are closely attached to the template and the end face and the template are inserted with a feeler gauge of 0.3 - 0.4 mm, the blade root size is qualified. The remaining dimensions are detected using the general three-coordinate detection method. In Step 6, to ensure the clamping accuracy of the blade, an integral blade root grinding fixture is designed for this process. The fixture is made of 45# square steel. The blade root positioning and clamping part is cut out by wire cutting, and a space for avoiding the blade steam passage is machined by fast wire cutting. The blade can be inverted in the fixture for clamping. The thickness of the positioning side wall of the fixture is designed to be 50 mm to ensure the clamping rigidity, and the thickness of the clamping side wall is designed to be 25 mm to ensure the elasticity of the fixture. At about 1 / 3 of the total height of the fixture, a M12 bolt is centrally arranged on the clamping side. The length of the bolt is such that it can push against the inner wall of the positioning side to spring open the blade root clamping part. After inserting the blade root, the bolt is loosened, and a C-type clamp is installed outside the fixture to clamp the fixture and simultaneously clamp the blade root, making the blade root end face exposed upward from the blade root fixture for easy grinding. The present invention replaces the design of a special milling cutter with a general cemented carbide rod cutter, and uses a five-axis linkage device to integrally process the blade steam passage and the blade root profile, improving the blade machining accuracy, reducing the design of special blade root milling cutters, and greatly reducing the blade machining cost and cycle.

[0041] Specific Embodiment 2: Refer to Figure 1-2 As shown, in Step 1 of this embodiment for machining the blade root process handle 2 and the blade crown process handle 3, the rough machining cutting depth is 0.5 - 0.7 mm, the machine tool speed is 60 - 100 r / min, and the feed rate is 30 mm / min for one cut; the finish machining cutting depth is 0 - 0.1 mm, the machine tool speed is 60 - 100 r / min, and the feed rate is 100 mm / min for one cut.

[0042] Specific Embodiment 3: Refer to Figure 1-2 As shown, in the rough machining of Step ② of this embodiment, the machining cutting depth is 1 mm, the machine tool speed is 636 r / min, and the feed rate is 250 mm / min;

[0043] Set the finish milling allowance: 0.5 mm for the blade root dovetail surface, 0.5 mm for the large surface on the air inlet side of the blade root, 0.7 mm for the air passage, and 0.5 - 1 mm for the other surfaces.

[0044] Specific Embodiment 4: Refer to Figure 1-2As shown, step three of this embodiment, finishing, consists of two steps: semi-finishing and finishing. The semi-finishing depth is 0.1-0.2 mm, the machine tool speed is 1200 r / min, and the feed is 100 mm / min. The finishing depth is 0-0.1 mm, the machine tool speed is 1200 r / min, and the feed is 100 mm / min.

[0045] Specific implementation method five: See Figure 1-2 As shown, in step five of this embodiment, the perpendicularity of the wire-cut blade root end face to the air intake side is 0.3, and the wire-cut surface is 0-0.5mm higher than the five-axis machining surface;

[0046] The cutting parameters are: pulse width 48μs, current 2A, voltage 90V, wire feed speed 60mm² / min.

[0047] Specific implementation method six: See Figure 1-2 As shown, in step six of this embodiment, the flat grinding of the blade root end face consists of two steps: semi-finishing and finishing. The roughing cutting parameters are a depth of cut of 0.02 mm, a rotation speed of 1440 r / min, and a feed of 140-150 mm / s. The finishing parameters are a depth of cut of 0.01 mm, a rotation speed of 1440 r / min, and a feed of 140-150 mm / s.

[0048] Detailed implementation method seven: See Figure 1-2 As shown, the blade blank of this embodiment includes a blade 1, a blade root process clamp 2, and a blade crown process clamp 3.

[0049] The blade root end of blade 1 is machined with a blade root process clamp 2, the blade crown end of blade 1 is machined with a blade crown process clamp 3, the connection between the blade root process clamp 2 and blade 1 is machined with a hollow tool groove 4, and the connection between the blade crown process clamp 3 and blade 1 is machined with a retraction extension section 5.

[0050] Furthermore, the blade root chamfer and the CNC-machined blade root end are both forged and shaped with a single-sided allowance of 5mm. Without affecting the clamping rigidity, a hollow tool groove 4 is opened on the blade root end face, and a retraction extension section 5 is made on the blade crown shank to avoid ineffective machining quotas during tool cutting and reduce idle tool travel time.

[0051] The distance from the end face of the blade root process shank 2 to the end face of the product is 40mm, and the height of the clamping part is 15mm. The width of the empty tool groove 4 is 20mm, and the bottom of the groove is 9mm lower than the two sides of the blank. The retraction extension section of the blade crown process head is 10mm, and the height of the blade crown process shank 3 is 20mm. The blade crown process shank 3 is used for clamping in a dual-drive device to ensure the stability of the blade posture during processing and avoid surface quality defects caused by twisting.

[0052] This invention optimizes the structure of the blade forging blank, designs a blade root process clamp and a blade crown process clamp, and opens a blade root center pin hole 6 at the center of the end face of the blade root process clamp 2, opens blade root side pin holes 7 on both sides of the blade root center pin hole 6, and opens a blade crown pin hole 8 at the center of the end face of the blade crown process clamp 3. This reduces the reference conversion in the processing process, makes the relative positional relationship between the processed blade root profile and the steam passage more accurate, and reduces the number of tooling designs, thus reducing tooling costs.

[0053] Detailed Implementation Method Eight: See also Figure 1-2 As shown, the leaf root process clamp 2 of this embodiment has a leaf root center pin hole 6 at the center of its end face, leaf root side pin holes 7 on both sides of the leaf root center pin hole 6, and a leaf crown pin hole 8 at the center of its end face.

[0054] Furthermore, to ensure the consistency of the depth of the three ejector pin holes at the blade root, a flat surface must be machined on the end face of the blade root clamp before drilling the ejector pin holes. A φ10 steel ball is used to check the hole depth to ensure that the 5.07 dimensional tolerance is ±0.05. The distance between the ejector pin hole 6 at the center of the blade root and the ejector pin hole 7 on the side of the blade root is 45mm.

[0055] Detailed implementation method nine: See Figure 1-2 As shown, in this embodiment, the leaf root center pin hole 6 and the leaf crown pin hole 8 are coaxially arranged.

[0056] Detailed Implementation Method Ten: See [link] Figure 1-2 As shown, the two leaf root side pin holes 7 in this embodiment are symmetrically arranged along the center line of the blade 1.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of dovetail root blade machining, characterized by: The method comprises the following steps: Step one, using three-axis vertical milling machine processing, the machine tool tip needle tight blade blank two blade root side top pin hole (7), blade crown end needle tight blade crown top pin hole (8), complete blade blank clamping, using φ20-25 insert hard alloy piece milling cutter on the blade root process handle (2) and blade crown process handle (3) are processed; Step two, using four-axis milling machine processing, the machine tool tip needle tight blade blank blade root center top pin hole (6), blade crown end needle tight blade crown top pin hole (8), and use jaw clamping blade root process handle (2), complete blade blank clamping, using φ40 end mill insert R6 high cutting blade edge on the blade (1) is rough machining; Step three, using five-axis linkage numerical control machining center for finishing, the machine tool tip needle tight blade blank blade root center top pin hole (6), blade crown end needle tight blade crown top pin hole (8), and use two jaw clamping blade root process handle (2) and blade crown process handle (3), complete blade blank clamping, using φ20 integral hard alloy milling cutter end blade processing dovetail blade root dovetail face, complete dovetail face processing spindle turn 60 degrees, using end blade processing dovetail chamfer face, then the tool spindle and blade (1) center line perpendicular to the tool side blade processing dovetail blade end face; Step four, wire cutting blade crown end face; Step five, wire cutting blade root end face; Step six, grinding accurate blade root end face, blade (1) blade root is placed vertically upward, using blade root clamp clamping blade root, using horizontal shaft square surface grinding machine grinding blade root end face.

2. The dovetail root blade machining method according to claim 1, characterized in that: In step one, the rough machining depth is 0.5-0.7mm, the machine tool speed is 60-100r / min, and the feed is 30mm / min for one cut; the finishing machining depth is 0-0.1mm, the machine tool speed is 60-100r / min, and the feed is 100mm / min for one cut.

3. The method of claim 1, wherein: In step two, the machining depth is 1mm, the machine tool speed is 636r / min, and the feed is 250mm / min; The finishing allowance is set as follows: the dovetail face of blade root is 0.5mm, the large face of blade root inlet side is 0.5mm, the air duct is 0.7mm, and the rest of the faces are 0.5-1mm.

4. The method of claim 1, wherein: In step three, the semi-finishing machining depth is 0.1-0.2mm, the machine tool speed is 1200r / min, and the feed is 100mm / min; the finishing machining depth is 0-0.1mm, the machine tool speed is 1200r / min, and the feed is 100mm / min.

5. The method of claim 1, wherein: In step five, the wire cutting blade root end face relative to the inlet side perpendicularity is 0.3, and the wire cutting is higher than the five-axis machining face by 0-0.5mm; The cutting parameters are as follows: pulse width 48μs, current 2A, voltage 90V, and wire speed 60mm² / min.

6. The dovetail root blade machining method according to claim 1, characterized by: In step six, the grinding of blade root end face comprises semi-finishing and finishing, the rough machining parameters are as follows: cutting depth 0.02mm, speed 1440r / min, and feed 140-150mm / s; the finishing parameters are as follows: cutting depth 0.01mm, speed 1440r / min, and feed 140-150mm / s.

7. The method of claim 1, wherein: The blade blank comprises a blade (1), a root process handle (2) and a crown process handle (3); The root process handle (2) is processed at the root end of the blade (1), and the crown process handle (3) is processed at the crown end of the blade (1), the connecting part of the root process handle (2) and the blade (1) is processed with an empty knife groove (4), and the connecting part of the crown process handle (3) and the blade (1) is processed with a tool withdrawal extension section (5).

8. The method of claim 7, wherein: A root center center pin hole (6) is arranged at the center of the end face of the root process handle (2), and root side center pin holes (7) are arranged on both sides of the root center center pin hole (6), and a crown center center pin hole (8) is arranged at the center of the end face of the crown process handle (3).

9. The method of claim 8, wherein: The root center center pin hole (6) and the crown center center pin hole (8) are coaxially arranged.

10. The method of claim 8, wherein: Two root side center pin holes (7) are symmetrically arranged along the center line of the blade (1).

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