Method and tooling for machining a hollow web slot R of an aerofoil blade

Abstract

A method for machining the anti-icing groove R of a hollow support plate for aircraft blades using a precision engraving machine. The precision engraving machine mills the hollow support plate, based on the following fixture: The fixture includes a base plate with dimensions larger than the hollow support plate; positioning blocks are provided on the base plate; two pads are fixed to the base plate by threads; the base plate is also fixed to the two positioning blocks by threads and pin holes; each positioning block has an anti-icing groove limiting strip groove on its upper surface; the two anti-icing groove limiting strips are respectively inserted into the two anti-icing groove limiting strip grooves; the limiting strips and limiting strip grooves are clearance fit, allowing 0.02-0.03 mm of freedom in the width direction and less than 0.1 mm of freedom in the length direction, to position the hollow support plate; pressure plates are provided to press down on both ends of the hollow support plate; the blank blade is measured with a probe to obtain actual measurement data, and based on the data to be processed, the deviation between the first surface to be processed and the theoretical value is determined; the remaining surfaces to be processed are measured based on the actual measurement value of the first surface to be processed.

Description

TECHNICAL FIELD

[0001] The application relates to a machining method for machining an R-shaped notch of an anti-icing groove of a hollow support plate of an aviation blade and matched tooling. BACKGROUND

[0002] An aero-engine is the heart of an airplane, and is not only the power of the airplane flight, but also an important driving force for promoting the development of the aviation industry. Every important change in the history of human aviation is closely related to the technological progress of the aero-engine. The aero-engine has developed into a mature product with extremely high reliability. The aero-engines in use include turbojet / turbofan engines, turbo-shaft / turboprop engines, ramjet engines and piston engines, and are not only used as the power of various civil airplanes, unmanned aerial vehicles and rockets, but also used in the fields of ground power generation, marine power, mobile power stations, natural gas and oil pipeline pump stations and the like by virtue of the derivative development of the aero-engine.

[0003] When a plane is designed, the parts that are easily hit by birds, such as the windshield, the radar cover and the wing leading edge, should be strengthened to withstand the impact of large birds. The above-mentioned parts are fixed on the plane, and are relatively easy to solve, but for the engine, it is more difficult because the fan blades behind the engine inlet are high-speed rotating, long and thin, and are easy to break when hit by a bird, which not only causes the engine vibration to increase, but also the broken pieces flow along the airflow to the rear of the engine and damage the subsequent components, and even cause the engine to stop. In order to solve the above problems, the hollow blade is currently generated, and the current hollow support plate still has a large space for improvement in the absorption of kinetic energy to adapt to more stringent requirements. In the face of such demand, how to improve the machining precision of the blade is worth pursuing.

[0004] The prior art for machining the notch includes CN201510158531.8 groove position adjustable core rod groove grinding device, which can automatically grind the groove on the core rod, and has high grinding precision and processing efficiency. The groove position adjustable core rod groove grinding device comprises a machine body, a feeding box, a feeding mechanism, an upper grinding mechanism, a lower grinding mechanism and a side pressing mechanism. A discharge opening through which the core rod can enter and exit is formed between the feeding box and the workbench. The push plate of the feeding mechanism pushes the core rod into the lower part of the upper grinding wheel and the upper part of the lower grinding wheel. The upper grinding mechanism is slidably arranged on the upper guide rail arranged on the machine body in parallel with the axis of the core rod. The upper translation screw is rotatably arranged on the machine body, and the upper translation slide block connected with the upper grinding mechanism is matched with the upper translation screw. The upper box body is arranged on the machine body and moves up and down in the direction perpendicular to the axis of the core rod.

[0005] The above mechanism is not suitable for processing the R of the ice prevention groove of the blade, and the ice prevention groove has a small size, the R of the groove is 0.2±0.05, and the ice prevention groove will be deformed, which causes great difficulty in processing

[0006] CN201310412511.X Slotting processing method, slotting processing tool and slotting processing tool holding structure, slotting processing tool and slotting processing tool holding structure, in the processing process, the chip is not easy to stay between the cutting edges and can reduce the load applied to the tool. The tool (1) is formed: a plurality of cutting edges (11) are arranged on the left and right sides of the blade (10) arranged in the longitudinal direction, and the cutting edges (11) arranged on one side are oriented downward, and the cutting edges (11) arranged on the other side are oriented upward, so that the tool (1) performs circular motion in the plane formed by the cutting edges (11) to cut.

[0007] The front process tolerance of the hollow strut workpiece of the aerofoil blade is large, which greatly affects the processing of the R of the ice prevention groove of the hollow strut of the aerofoil blade, and the tolerance is not easy to guarantee. In addition, the hollow strut workpiece of the aerofoil blade is processed after welding, and the slot shape, size, angle and position of the ice prevention groove on the workpiece change greatly and have no rules, which leads to the fact that the size, shape tolerance and surface roughness of the processed part cannot be guaranteed during processing.

[0008] In summary, at present, the R of the ice prevention groove of the hollow strut is generally repaired by clamping, and when the R of the ice prevention groove of the hollow strut of the aerofoil blade is repaired by clamping, the surface roughness will have processing marks and irregular microscopic cracks. The front process tolerance of the workpiece is large, which greatly affects the processing of the R of the ice prevention groove of the hollow strut of the aerofoil blade, and the tolerance is not easy to guarantee. In addition, the workpiece is processed after welding, and the workpiece has the defects that the slot shape, size, angle and position change greatly and have no rules, which leads to the fact that the size, shape tolerance and surface roughness of the processed part cannot be guaranteed during processing.

[0009] From the analysis of the processing technology of the R of the ice prevention groove of the hollow strut and the application of the prior art, it can be seen that when the R of the ice prevention groove of the hollow strut is processed by repairing, it is difficult to guarantee the precision of R.

[0010] The R of the ice prevention groove of the hollow strut needs to guarantee precision and roughness, and milling is the best way, but the existing way cannot guarantee precision and roughness. At present, there is no good method for processing. SUMMARY

[0011] In order to solve the above machining problems, the purpose of the present application is to provide a machining method for machining the R of the ice-preventing groove of the hollow support plate of the aviation blade by the precision carving machine, the workpiece can be precisely positioned in the axial and longitudinal directions by the ice-preventing groove limiting strip, the workpiece clamping efficiency is high, the device (tooling) for machining the R of the ice-preventing groove of the hollow support plate is used, the conventional machining method needs to be repaired to realize, and the precision carving machine can be used to realize the present application, the rigidity of the workpiece machining is increased, the tool shaking during machining is avoided, the deformation during machining can be effectively prevented, and the machining precision and roughness of the workpiece are ensured.

[0012] The technical scheme of the present application is a machining method for machining the R of the ice-preventing groove of the hollow support plate of the aviation blade by the precision carving machine, the hollow support plate is milled by the precision carving machine, and the tooling is based on the following tooling, the tooling includes a bottom plate with a size and shape larger than the hollow support plate, the bottom plate is provided with a positioning block accommodating and matching the shape of the hollow support plate blank (the lower surface shape of the hollow support plate blank is matched), the bottom plate 1 is fixed with two pads 2 and 11 through threads, the bottom plate 1 is fixed with two positioning blocks 7 and 10 through threads and pin holes, the upper surfaces of the positioning blocks 7 and 10 are respectively provided with an ice-preventing groove limiting strip slot, two ice-preventing groove limiting strips are respectively inserted into the two ice-preventing groove limiting strip slots, the limiting strip and the limiting strip slot are gap-fitted, the width direction allows a freedom of 0.02-0.03 mm, and the length direction allows a freedom of within 0.1 mm, so as to position the hollow support plate 3 by the ice-preventing groove limiting strip; the (upper) pressing plate 4 and 14 are provided and press the two ends of the hollow support plate 3, the upper pressing plate tightly presses the upper surface of the hollow support plate through the outer hexagonal nut, and the upper pressing plate and the hollow support plate are fixed; finally, the ice-preventing groove limiting strips in the ice-preventing groove limiting strip slots are pulled out, if the ice-preventing groove limiting strips are smoothly pulled out, it indicates that the blade does not displace and deform after being pressed, the machining is performed according to the measured size, if the ice-preventing groove limiting strips are difficult to pull out, it indicates that the blade displaces and deforms after being pressed, the blade needs to be re-measured by the measuring needle on the surface to be machined, and the measured data are obtained, so as to ensure the accuracy of the fixed part.

[0013] The probe is used to measure the blank blade to obtain the measured data before R groove machining, and the deviation of the first surface to be machined of the blank blade from the theoretical value is found according to the data to be machined; the remaining surfaces to be machined are measured according to the measured value of the first surface to be machined, and the tolerance is set, if the range is exceeded, there will be feedback, the data are adjusted on site, the coordinate calibration (reference point) of the workpiece is performed after the tooling of the actual precision carving machine (machine tool) is assembled, and the fine adjustment is performed, and then the milling machining is performed.

[0014] The actual fine carving machine (machine tool) is used for installing the coordinate calibration (reference point) of the workpiece and fine adjustment, the purpose is to measure all the size data to be processed, adjust the tolerance according to the measured size, assign values through the field macro program, to meet the requirements of single slot shape tolerance and roughness, and use the super-speed small-amount fine carving machine to mill the R of the ice-preventing groove of the hollow support plate, so as to reduce the surface vibration and defects, and ensure the consistency and stability.

[0015] Two pads are used for supporting the hollow support plate 3 (blank); after the hollow support plate blank is installed, an upper pressing plate is arranged above the edge of the hollow support plate blank to press tightly, the upper pressing plate and the bottom plate are fixed through screwing; the bottom plate and the positioning block are fixed through pin positioning and screwing, the positioning block and the hollow support plate are positioned through the ice-preventing groove limiting strip, and the workpiece, the bottom plate, the positioning block and the upper pressing plate are pressed tightly through screws, and then milling is carried out.

[0016] Compared with the prior art, the present application has the following advantages: the hollow support plate is positioned by the ice-preventing groove limiting strip on the upper surface of the positioning block, and the upper and lower ends of the hollow support plate are positioned and fastened by the pads and the upper pressing plate, so that the hollow support plate will not displace during processing, the rigidity and accuracy of the workpiece can be improved during processing of the hollow support plate, and the surface vibration and defects are reduced. The machining precision of the fine carving machine can reach more than 0.01 mm (and the quality fully meets the requirements, the stress distribution is uniform when used, and no cracks are generated at the slot), the precision fully meets the standard, the quality requirements of the hollow support plate are met, the equipment runs stably and reliably, the processing quality is good, the processing cost is low, the efficiency is high, the operation is simple, and the maintenance is convenient. The existing hollow support plate workpiece of the aviation blade is processed after welding, and the slot hole shape, size, angle and position of the ice-preventing groove on the workpiece change greatly and have no rules, so that the size, shape tolerance and surface roughness of the processed part cannot be guaranteed.

[0017] In practice, the present application can still achieve a precision of 0.01 mm (the error is within 10 microns) when processing the R of the ice-preventing groove of the hollow support plate, which is high enough for the precision of the R of the ice-preventing groove of the hollow support plate, and is much better than other methods. Moreover, the overall rigidity of the clamped workpiece is good, and the fixation is very firm and reliable. If the part precision and surface requirements are high, the fine carving machine is preferred for better effect. The present application can increase the accuracy of the reference point of the workpiece rigidity, avoid tool vibration during processing, effectively prevent deformation during processing, and ensure the workpiece machining precision. The fine carving machine processing device provided by the present application can effectively lock the axial and longitudinal positions of the workpiece, and the positioning is accurate, so that the workpiece is convenient to clamp, the method is simple, the use is very convenient, the clamping time of the workpiece is greatly shortened, and the processing efficiency is improved. The conventional processing method needs to be repaired, and the present application can use the fine carving machine to achieve the purpose, reduce the production cost, and ensure the surface roughness and machining precision.

[0018] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the anti-icing groove R device for the hollow support plate of the aircraft blade processed by a precision engraving machine.

[0020] Figure 2 This is a schematic diagram of the anti-icing groove R of the hollow support plate of an aircraft blade processed by a precision engraving machine;

[0021] Figure 3 This is a schematic diagram of the anti-icing groove R of the hollow support plate of an aircraft blade before machining;

[0022] Figure 4 This is a magnified 50x photo of the anti-icing groove and groove R of the hollow support plate of the aircraft blade after machining by a precision engraving machine. Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings.

[0024] like Figure 1 As shown, the device for machining the anti-icing groove R of the hollow support plate of aircraft blades using a precision engraving machine includes a base plate 1.

[0025] The base plate 1 has three threaded holes M10 at each end. The base plate 1 supports the hollow support plate 3 through threaded mating pads 2 and 11. The base plate 1 has countersunk holes, pin holes, and threaded holes. The base plate and the hollow support plate are supported by pads at both ends, and the pads at both ends are fixed to the base plate by screws. After the hollow support plate blank is installed, a pressure plate is provided to press it from above the edge of the hollow support plate blank. The upper pressure plate is fixed to the base plate by screws. The base plate and the hollow support plate are positioned in the length direction and side by anti-icing groove limiting strips. The base plate 1 is fixed to positioning blocks 7 and 10 by threads and pin holes. The upper surface of positioning blocks 7 and 10 has grooves as anti-icing groove limiting strip grooves 13. The anti-icing groove limiting strips are inserted into the limiting strip grooves and fixed to positioning blocks 7 and 10. The positioning block is only used to hold the anti-icing groove limit strip and does not directly contact the hollow support plate of the aircraft blade; the anti-icing groove limit strip is inserted into the anti-icing groove limit strip groove, with clearance fit, allowing 0.02 to 0.03 degrees of freedom in the width direction and less than 0.1 degrees of freedom in the length direction. The anti-icing groove limit strip positions the hollow support plate 3.

[0026] The anti-icing groove limit strip serves as a reference for the transfer of the processing device and provides basic positioning. The anti-icing groove limit strip 14 is the positioning reference for the processing device. It can also be used as a positioning reference for processing the next workpiece.

[0027] The bottom plate 1 is provided with a threaded hole M12, the stud bolts 5, 10 are threadedly connected with the threaded hole, the stud bolts 5, 10 are provided with the pressing plates 4, 12, which press the hollow support plate 3 at two ends respectively, the stud bolts 5, 10 are provided with the nuts 6, 11 at top ends, the upper pressing plate is pressed tightly on the upper surface of the hollow support plate through the outer hexagonal nut, the outer hexagonal nut is tightened to fix the upper pressing plate and the hollow support plate, finally, the ice prevention groove limiting strips 14 in the ice prevention groove limiting strip grooves are pulled out respectively, if the ice prevention groove limiting strips are pulled out smoothly, it indicates that the blade does not displace and deform after being pressed tightly, the actual measured size is measured to process, if the ice prevention groove limiting strips are pulled out with great effort, it indicates that the blade displaces and deforms after being pressed tightly, the blade needs to be measured again by using the measuring needle on the surface to be processed, and the actual measured data is obtained, so that the accuracy of the fixed part is ensured.

[0028] The upper pressing plate is pressed tightly on the upper surface of the hollow support plate through the outer hexagonal bolt, the inner hexagonal screw is tightened to fix the upper pressing plate and the hollow support plate; the hollow support plate is fixed on the bottom plate and fixed with the working platform of the engraving and milling machine, and then milling is performed.

[0029] The machining device for the ice prevention groove slot R of the hollow support plate of the aviation blade provided by the application can effectively lock the axial and longitudinal positions of the workpiece, is accurate in positioning, is convenient in workpiece clamping, is simple in method, is very convenient to use, greatly shortens the clamping time of the workpiece, and improves the machining efficiency. The conventional machining method needs to be repaired, and the machining method can be realized by using the engraving and milling machine, so that the production cost is reduced, the surface roughness and the machining precision are ensured.

[0030] The upper pressing plate and the screw are on the upper surface of the hollow support plate, and the hollow support plate is positioned in the length direction and the side surface through the ice prevention groove limiting strip, so that the accuracy of the whole machining body is ensured.

[0031] The bottom plate is directly fixed on the working platform of the engraving and milling machine (CNC) numerical control machine tool. In use, the hollow support plate 3 of the blade is placed on the upper surfaces of the pads 2, 9, the ice prevention groove limiting strips pass through the ice prevention grooves 15 of the hollow support plate 3 (the ice prevention grooves have been processed on the hollow support plate 3, Figure 3There are 17 anti-icing grooves 15 (in this invention, the groove opening is processed into an R-groove). The anti-icing groove through which the anti-icing groove limiting strip passes refers to the two anti-icing grooves located on the two sides in the middle. The precision of the anti-icing groove limiting strip and the fit between the groove and the recess are as described above: the width direction allows 0.02 to 0.03 degrees of freedom, the length direction allows 0.1 degrees of freedom, and the anti-icing groove limiting strip freely passes through the anti-icing groove and matches the anti-icing groove limiting strip groove) is inserted into the anti-icing groove limiting strip groove, so that the position of the hollow support plate 3 is fixed. The double-ended studs 5 and 10 are screwed into the threaded holes M12 on the base plate 1 respectively. The pressure plates 4 and 12 pass through the double-ended studs 5 and 10 respectively, and press the two ends of the hollow support plate 3 respectively. Nuts 6 and 11 are screwed into the double-ended studs 5 and 10, and the hollow support plate 3 is pressed tightly by the pressure plates 4 and 12, while fixing the hollow support plate 3 and the pads 2 and 9. When machining R-grooves with a CNC engraving machine, the insert specification is an R0.4 carbide ball end mill. The specific process for machining R-grooves is as follows: a unidirectional helical rotary sinking machining method is used, employing high-speed, low-cutting-amount (typically 50-70% of the feed rate) at high speeds (above 3000 RPM). CNC engraving machines can machine all R-grooves in one go through programming (the origin can be defined as an edge point of a specific anti-icing groove limit strip during programming), instead of multiple grooves... Figure 3 The machining of the 17 grooves is done by sawing with a milling cutter. The position of all the anti-icing grooves is confirmed. The smoothness of the R groove machining in this invention is extremely important and is an important means to ensure that the machine parts can overcome stress.

[0032] In summary, the invention uses pads 2 and 9 and pressure plates 4 and 12 to position the hollow support plate 3 vertically. The anti-icing groove limiting strip passes through the anti-icing groove of the hollow support plate 3 and inserts into the anti-icing groove limiting strip groove, thus fixing the position of the hollow support plate 3. It is then secured with double-ended studs 5 and 10 and nuts 6 and 11. The nuts press the workpiece, pads, and pressure plates tightly. This method increases the rigidity of the workpiece during processing, preventing displacement of the hollow support plate and avoiding vibration, tool deflection, and deformation. It effectively prevents processing errors caused by deformation during processing and ensures surface roughness. The upper surfaces of positioning blocks 7 and 8 are provided with anti-icing groove limiting strip grooves. The anti-icing groove limiting strip is inserted into the anti-icing groove limiting strip groove, positioning the hollow support plate 3 and thus ensuring the rigidity of the fixed parts.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications can also be regarded as the protection scope of the present invention.

Claims

1. A machining method for machining the R of the notch of the ice-prevention groove of the hollow strut of an aerofoil blade by a fine carving machine, characterized in that, The hollow support plate is milled by using a precision carving machine, and based on the following tooling, the tooling includes a bottom plate with a size and shape larger than the hollow support plate, the bottom plate is provided with positioning blocks, i.e., positioning block one and positioning block two, the bottom plate (1) is fixed with two pads, i.e., pad one and pad two, by threads, and the bottom plate is fixed by threads and pin holes; the upper surfaces of the positioning block one and the positioning block two (7, 10) are each provided with an anti-icing groove limiting strip groove, two anti-icing groove limiting strips are respectively inserted into the two anti-icing groove limiting strip grooves, the anti-icing groove limiting strip and the anti-icing groove limiting strip groove are gap-fitted, the width direction allows a freedom of 0.02-0.03mm, and the length direction allows a freedom of within 0.1mm, so as to prevent the anti-icing groove limiting strip from positioning the hollow support plate; the pressing plates, i.e., pressing plate one and pressing plate two (4, 12), press the two ends of the hollow support plate respectively, the upper surface of the hollow support plate is pressed tightly by an outer hexagonal nut, the upper pressing plate is fixed, and the hollow support plate is fixed; finally, the anti-icing groove limiting strips in the anti-icing groove limiting strip grooves are pulled out respectively, if the anti-icing groove limiting strips are pulled out smoothly, it indicates that the blade does not displace or deform after being pressed tightly, the actual measured size is measured, and the blade is processed according to the measured data, if the anti-icing groove limiting strips are pulled out with difficulty, it indicates that the blade displaces or deforms after being pressed tightly, the blade needs to be measured again by using a measuring needle for the surface to be processed, and actual measured data is obtained, so as to ensure the accuracy of the fixed part. The actual measured data of the blank blade is measured by using a probe, and the deviation between the first surface to be processed of the blank blade and the theoretical value is found according to the data to be processed; the remaining surfaces to be processed are measured according to the actual measured value of the first surface to be processed, the coordinates of the tooling and the workpiece are calibrated after the precision carving machine is installed, and then milling is performed.

2. The method of claim 1, wherein: The upper surfaces of the bottom plate are used for installing the positioning block one, the positioning block two, the pad one and the pad two, and the lower surfaces of the bottom plate are respectively provided with four inner hexagonal screws arranged on the numerical control precision carving machine.

3. The method of claim 1, wherein: The pressing plate one and the pressing plate two are metal plates with a thickness of 15mm, the lower surfaces of the pressing plate one and the pressing plate two are surfaces in contact with the upper surface of the hollow support plate, the surfaces of the pressing plate one and the pressing plate two are provided with through holes, and the pressing plate one and the pressing plate two are fixed to the bottom plate by double-headed bolts.

4. The method of claim 2, wherein: The pad one and the pad two (11) are flat pads, the surfaces of the pad one and the pad two are provided with countersunk holes, the two ends of the bottom plate are respectively provided with threaded holes, and the pad one and the pad two are fixed to the bottom plate by three inner hexagonal screws.

5. The method of claim 1 wherein: The positioning block one and the positioning block two are four-sided bodies, the lower surfaces of the positioning block one and the positioning block two are surfaces in contact with the bottom plate (1), the lower surfaces of the positioning block one and the positioning block two are provided with threaded holes and pin holes, the two ends of the bottom plate (1) are respectively provided with countersunk holes as pin holes, and the positioning block one and the positioning block two can be fixed to the bottom plate.

6. The method of claim 1, wherein: The anti-icing groove limiting strip is a metal strip with the shape of the anti-icing groove limiting strip groove, the upper surfaces of the positioning block one and the positioning block two are respectively provided with recesses as the anti-icing groove limiting strip grooves, and the anti-icing groove limiting strip can be inserted into the anti-icing groove limiting strip groove to be fixed to the positioning block one and the positioning block two.

7. The method of claim 1 wherein: The precision carving machine is a numerical control machine tool.

8. The method of claim 1 wherein: The pressing plate one and the pressing plate two are metal plates with a height of 20mm, the lower surfaces of the pressing plate one and the pressing plate two are stepped surfaces in contact with the upper surface of the hollow support plate, the surfaces of the pressing plate one and the pressing plate two are provided with countersunk holes, and the pressing plate one and the pressing plate two can be fixed to the bottom plate.

9. The method of claim 1 wherein: The specification of the cutter is R0.4 hard alloy ball head cutter when processing the anti-icing groove notch R. The specific process of processing the anti-icing groove notch R is as follows: one-way spiral rotation sinking processing, high-speed micro cutting amount, and high-speed processing mode.

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