A method for machining a conical section with convexity and dense air film hole

Abstract

The application discloses a kind of convex hull and dense gas film hole cone section precision machining method, including successively preparing cone cylinder blank, roll flange edge, correcting the profile of cone cylinder blank, heat correcting the profile contour of cone cylinder blank, cutting the small diameter end of cone cylinder blank and positioning hole, electric spark blows gas film hole, presses nest and punches, processes the large diameter end of cone cylinder blank to obtain the outer diameter and height of cone cylinder blank.The machining method of the application uses the same positioning datum and datum transmission, cooperates correction and heat correction, ensures the size accuracy of conical surface and the accurate spacing of convex hull, concentric small hole on convex hull and gas film hole, greatly improves the processing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine processing technology, and in particular, it is a processing method for a conical section of an aero-engine with a convex bulge and dense film gas holes. Background Technology

[0002] like Figure 1 The cone section with protrusions and densely packed film-forming holes shown is a hot-end component of an aero-engine. The part is a thin-walled conical cylindrical part with very high roundness requirements, a surface profile tolerance of 0.4 mm, and six evenly distributed inwardly concave protrusions. Each protrusion has concentric small holes, and at the smaller diameter end, there are 10 rows of small holes (with a diameter of [missing information]) serving as film-forming holes. The holes are evenly distributed, with 140 holes in the bottom row and 50 holes in the top row, increasing by 10 holes per row. The spacing between holes in the same row is 10mm. The current processing method involves welding sheet metal into a conical cylinder, manually rounding it, then machining the large and small diameter ends, followed by machining the air film holes, bulges, and concentric holes. This process makes it difficult to guarantee the surface profile, requires a large amount of manual correction, results in poor surface quality, and, due to uneven machined end faces, the spacing between air film holes and concentric holes on the bulges cannot be guaranteed. Therefore, researching a reasonable and feasible processing method is particularly urgent. Summary of the Invention

[0003] In view of the problems described in the background art, the present invention aims to provide a precision machining method for a tapered section with a convex hull and dense air film holes, which improves machining efficiency while improving part quality and yield.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for precision machining a tapered segment with a convex hull and densely packed air film holes includes the following steps:

[0006] Step 1: Prepare the cone blank. The cone blank is made of sheet metal. The sheet metal is cut into fan-shaped pieces, and then rolled and welded into a cone blank.

[0007] Step 2: Roll the flange edge. Roll a flange edge perpendicular to the axis of the cone blank on a two-axis rolling machine at the large-diameter end of the cone blank.

[0008] Step 3: Correction, correct the cone profile of the cone blank;

[0009] Step 4: Hot straightening, to remove the welding stress from Step 1, and at the same time correct the roundness of the cone blank through hot straightening;

[0010] Step 5: Cut the small diameter end and positioning hole of the cone blank, and use the profile of the cone blank for positioning and clamping. First cut the small diameter end, then move it a distance to the large diameter end and cut the positioning hole.

[0011] Step 6: Electric spark hole drilling, taking the small diameter end of the cone blank as the machining reference, and using electric spark hole drilling to process the air film hole according to the drawing requirements;

[0012] Step 7: Pressing and punching, positioning the indent after positioning the hole in step 5, and then punching;

[0013] Step 8: Cutting the large diameter end to obtain the required outer diameter and height size.

[0014] Specifically, in step 1, when preparing the cone blank, the radial dimension of the cone blank is inwardly contracted based on the final required size of the part, and the small diameter end and the large diameter end are both extended along the part profile for a distance and then unfolded into a fan-shaped material. The fan-shaped material is divided into two halves (split along the fan generatrix), rolled, polished, and positioned and welded, and finally the two halves are welded to form a cone blank, which is ready for use after passing the air tightness check;

[0015] Specifically, in step 1, after the cone blank is welded, the roundness is corrected, and the weld is not allowed to protrude outwardly from the cone blank.

[0016] Specifically, in step 2, the flange edge is rolled using a two-axis rolling bed, and the rollers of the two-axis rolling bed are cylindrical rollers without profile. The large diameter end of the cone blank is rolled to process the flange edge, and the flange edge is perpendicular to the axis of the cone blank.

[0017] Specifically, in step 3, the correction device is a hydraulic machine, and the correction die has a pressing edge structure. The correction die is lifted up while pressing the flange edge, and the conical surface of the cone blank is corrected.

[0018] As an option, in step 3, the flange edge forms part of the large diameter end of the cone blank during the correction process, i.e. the flange edge is straightened to the direction of the conical surface generatrix during the correction process, becoming a part of the large diameter end of the conical surface of the cone blank.

[0019] Specifically, in step 4, the hot correction is carried out using a vacuum heat treatment furnace, and a hot correction tooling is used. The hot correction tooling includes a male die and a female die. The hot correction is achieved by the difference between the material thermal expansion coefficient of the male die and the female die and the thermal expansion coefficient of the part material, and the part surface profile is stabilized and the welding stress is removed.

[0020] Specifically, in step 5, the small diameter end and the positioning hole are cut using a laser cutting machine, and a profile positioning clamp is used for installation and processing;

[0021] Specifically, in step 5, the profile positioning clamp used for cutting has a positioning surface that is the conical inner profile of the non-hole part of the cone blank. The positioning surface is divided into two sections along the axial direction of the cone blank, and there is a gap between the two sections.

[0022] Specifically, in step 5, after the axis of the conical cylinder blank is aligned, the small-diameter end of the conical cylinder blank is first cut, and then a pair of small holes are cut on the same circumferential line at a height from the large-diameter end of the conical cylinder blank, with the equidivision points of the circumference as the center and symmetrically on both sides of the equidivision points, as the positioning holes for subsequent indentation.

[0023] Specifically, in step 6, the electric spark drilling is positioned by the inner profile of the conical cylinder blank, the profile positioning clamp in step 5 is used, the small-diameter end face is aligned, and the gas film hole is processed according to the drawing requirements.

[0024] Specifically, in step 7, the indentation adopts a punch as the equipment, and is positioned by the positioning hole in step 5, and then the indentation is pressed and the hole is punched.

[0025] Specifically, in step 8, the cutting of the large-diameter end adopts a laser cutting machine as the equipment, and is positioned by the inner profile of the conical cylinder blank to ensure the outer diameter of the large-diameter end and the height of the conical cylinder blank.

[0026] Compared with the prior art, the present application proposes a precise machining method for a conical section with a convex bundle and dense gas film holes, which adopts the same positioning reference and reference transmission through a reasonable process route and machining method, ensures the dimensional accuracy of the conical profile of the part and the accurate spacing of the convex bundle, the concentric small holes on the convex bundle and the gas film holes, and greatly improves the labor efficiency. The machining method has been used in the field, and the purpose and requirements of the present application have been achieved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a front view of a conical section with a convex bundle and dense gas film holes;

[0028] Figure 2 is a schematic view of cutting the small-diameter end, cutting the positioning hole and rolling the edge of the conical section with a convex bundle and dense gas film holes. DETAILED DESCRIPTION

[0029] The present application will be further described below in conjunction with the drawings and specific embodiments, but it should not be understood that the scope of the subject matter described herein is limited to the following embodiments. Any modifications, substitutions and changes made according to ordinary technical knowledge and conventional means without departing from the above technical idea of the present application are included in the scope of the present application.

[0030] As shown in Figure 1 and Figure 2 , a precise machining method for a conical section with a convex bundle and dense gas film holes is designed in the present embodiment, which includes the following steps:

[0031] Step 1: preparation of the cone blank, the cone blank is processed from sheet metal, laser cutting into two identical fan-shaped materials, and then respectively bending and welding for subsequent processing (of course, it can also be directly bent and welded into a cone blank from a fan-shaped material);

[0032] Step 2: roll the flange, roll a flange perpendicular to the axis of the cone blank on the two-axis roll bed at the large diameter end of the cone blank;

[0033] Step 3: correction, correct the conical surface of the cone blank on the correction die;

[0034] Step 4: hot correction, remove the welding stress, and at the same time, correct the roundness of the cone blank in the hot correction die;

[0035] Step 5: cutting the small diameter end and positioning hole, positioning and pressing the conical surface of the cone blank on the laser cutting equipment, cutting the small diameter end to ensure its diameter, and cutting the positioning hole (6) downward (i.e. Figure 1 from the small diameter end of the cone blank to the large diameter end) by a certain size; Figure 2

[0036] Step 6: electric spark drilling, taking the small diameter end as the processing reference, drilling 10 rows of small holes to form the air film hole according to the requirements; Figure 1

[0037] Step 7: pressing and punching, positioning with the positioning hole cut in step 5, then pressing to form a convexity and then punching to form a concentric small hole;

[0038] Step 8: processing the large diameter end of the cone blank, cutting the large diameter end to ensure that the outer diameter of the large diameter end and the height of the cone blank meet the requirements of the drawing.

[0039] In the above step 1, the cone blank is processed from sheet metal, the diameter of the cone blank is proportionally shrunk inward by 1-5mm compared to the final required outer diameter size of the part, the small diameter end extends upward (above the small diameter end in Figure 1 ) by 5-8mm along the profile, and the large diameter end also extends downward (below the large diameter end in Figure 1 ) by 15-20mm along the profile, then the cone blank is unfolded into a fan-shaped material, split into two identical fan-shaped materials, and then bent, polished, positioned, welded by argon arc welding to form a cone blank, which is ready for use after passing the air tightness check;

[0040] After the cone blank prepared in the above step 1 is welded by argon arc welding, the roundness after correction is not greater than 5, the weld is not allowed to protrude, and can be concave, but the concave amount is not greater than the bulging amount during correction in step 3;

[0041] ​​​In step 2 above, the flange edge is rolled using a two-axis rolling machine with profileless cylindrical rollers. The flange edge is rolled on the large-diameter end of the conical blank. The flange edge is perpendicular to the axis of the conical blank, and the flange edge width B is not less than 10mm.

[0042] In step 3 above, the equipment used for correction is a hydraulic press, and the correction mold is a stretching mold with a pressing edge structure. The correction mold lifts the pressing edge structure to press the flange edge of the cone blank, and the punch is fixed on the lower template. The upper template drives the die and the cone blank to fall together and fit against the forming surface of the punch. Finally, the cone shape of the cone blank is corrected. The pressing force is not less than 100T. After correction, the flange edge is allowed to be straightened, that is, the flange edge is stretched and flipped to extend along the cone surface, or the flange edge is corrected to become a part of the cone surface (coplanar).

[0043] In step 4 above, the heat-calibrating equipment is a vacuum heat treatment furnace, using a special heat-calibrating fixture. The cone blank is placed in the gap between the mold surfaces after the punch and die are closed and heated. The surfaces of the punch and die are aligned with the cone section with the convex bulge and dense air film holes. Figure 1 The profile of the cone blank is consistent with that shown. The punch and die of the hot straightening tooling should take into account the difference between their thermal expansion coefficients and those of the cone blank material. The difference in thermal expansion between the two is used to achieve the extrusion straightening of the cone blank during the heating and holding process. The surface profile of the cone blank is stabilized and welding stress is removed through hot straightening.

[0044] In step 5 above, the equipment used for cutting the small diameter end and positioning holes is a laser cutting machine, and the profile positioning fixture is used for the installation and processing of the cone blank;

[0045] The positioning surface of the profile positioning fixture used in step 5 above is the inner profile of the cone blank in the part without holes (i.e., the part without openings). The positioning surface is divided into two sections. The length of each section (corresponding to the axial length of the cone blank) is not less than 50mm. The axial distance between the two sections of the positioning surface should be extended as much as possible to ensure the accuracy of the positioning of the cone blank.

[0046] In step 5 above, after aligning the axis of the conical blank, first cut the small-diameter end of the conical blank, ensuring the size of the small-diameter end is D1±0.2mm. Then, machine a positioning hole at the large-diameter end of the part, i.e., at a height of (H+5)±0.1mm from the small-diameter end. Two positioning holes are cut circumferentially at positions 10mm apart, centered on the Φd1 small hole. The small hole serves as the reference positioning hole for subsequent indentation.

[0047] In step 6 above, an electrical discharge machining (EDM) device is used, and the laser cutting end face fixture from step 5 is used for clamping. The inner surface of the conical blank is used for positioning, and the small-diameter end face is aligned. Figure 110 exhaust film holes are required to be processed;

[0048] In step 7, the indenting and punching are performed by a 5000KN puncher, and the two small holes with diameter of Φd1 are used to position the two sides of the small hole The indenting is performed first, and then the punching is performed, so as to ensure the depth of the indenting and the diameter of the concentric small hole;

[0049] In step 8, the large-diameter end is cut by a laser cutting machine, and the same inner conical surface of the conical blank is used for positioning. After being clamped by the same surface positioning clamp in step 5, the large-diameter end (including the flange edge) is cut, so as to ensure the size D2±0.2mm of the large-diameter end and the height H of the conical blank. Figure 1

[0050] For example, the sizes shown in the table are taken as an example, D1=Φ46mm, D2=Φ287mm, H=187mm, L=20.3mm, Φd=Φ0.8mm, Φd1=Φ6mm, and the precise machining method of the conical segment with convex and dense gas film holes is as follows: Figure 1 Step 1: preparing a conical blank, the conical blank is prepared by

[0051] Figure 1 In step 7, the indenting and punching are performed by a 5000KN puncher, and the two small holes with diameter of Φd1 are used to position the two sides of the small hole

[0052] Step 2: rolling the flange edge, the large-diameter end of the conical blank is rolled on a two-axis rolling machine to form a flange edge which is perpendicular to the axis of the conical blank, and the width of the flange edge is 13mm;

[0053] Step 3: correction, the conical surface of the conical blank is corrected by pressing the flange edge on a correction die, and the roundness of the part in a free state is not greater than 3mm;

[0054] Step 4: hot correction, the welding stress is removed, and at the same time, the surface profile of the conical blank is corrected in the hot correction die, and the surface profile is not greater than 0.4mm, so as to stabilize the size precision of the surface profile;

[0055] Step 5: cutting the small-diameter end and positioning hole, the inner surface is positioned on a laser cutting device, the outer surface is pressed, the small-diameter end is cut, the diameter size is ensured, and at the same time, the two small holes are moved downward by 192±0.1mm, six groups of positioning holes are cut, the circumferential center distance of the small holes is 10±0.2, and the hole diameter is

[0056] ​​Step 6: Electric spark drilling, positioning with the inner profile of the cone blank, aligning the small diameter end with the center axis of the cone blank, taking the small diameter end as the machining reference, drilling n i rows of Φ0.8mm small holes as the air film holes according to the drawing; Figure 1

[0057] Step 7: Pressing the pocket and punching, positioning with the small hole, pressing the pocket and punching on the punch press, requiring to press the pocket first and then punch the Φ6mm small hole;

[0058] Step 8: Machining the large diameter end, positioning with the inner profile of the cone blank on the laser cutting machine, pressing the outer profile, cutting the large diameter end, ensuring the size Φ287±0.2mm and the height 187mm.

[0059] The content not described in detail in the specification of the present application belongs to the prior art known to those skilled in the art. Although the above describes the specific embodiments of the present application in a descriptive manner, so that those skilled in the art can understand the present application, it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and limited by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.​​

Claims

1. A method for precision machining of a conical section with a convexity and dense gas film hole, characterized in that, It comprises the following steps: Step 1: preparing a conical cylinder blank, the conical cylinder blank is processed by sheet metal, the sheet metal is cut into a fan-shaped material, then rolled and welded into a conical cylinder blank; Step 2: rolling flange, rolling a flange perpendicular to the axis of the conical cylinder blank on the two-axis rolling bed of the large diameter end of the conical cylinder blank; Step 3: correction, correcting the conical surface of the conical cylinder blank; Step 4: hot correction, removing the welding stress in step 1, and correcting the roundness of the conical cylinder blank by hot correction; Step 5: cutting the small diameter end and positioning hole of the conical cylinder blank, positioning and pressing the conical surface of the conical cylinder blank, cutting the small diameter end first, then cutting the positioning hole after moving a distance to the large diameter end; Step 6: electric spark drilling, taking the small diameter end of the conical cylinder blank as the machining reference, and processing the gas film hole by electric spark drilling according to the drawing requirements; Step 7: pressing and punching, positioning and pressing the positioning hole in step 5, and then punching; Step 8: cutting the large diameter end to obtain the required outer diameter and height size; In step 3, the correction device is a hydraulic machine, the correction die has a pressing edge structure, the correction die is lifted up while pressing the flange, and the conical surface of the conical cylinder blank is corrected; In step 3, the flange forms part of the conical surface of the large diameter end of the conical cylinder blank during the correction process; In step 5, the small diameter end and the positioning hole are cut by a laser cutting machine, and a surface positioning clamp is used for installation and processing; In step 5, the surface positioning clamp used for cutting has a conical inner surface as the positioning surface on the non-hole part of the conical cylinder blank, the positioning surface is divided into two sections along the axial direction of the conical cylinder blank, and there is a gap between the two sections; In step 5, after the axis of the conical cylinder blank is aligned, the small diameter end of the conical cylinder blank is cut first, then a pair of small holes are cut as positioning holes for subsequent pressing at a height from the large diameter end of the conical cylinder blank on the same circular line, with the equidivision points of the circle as the center and symmetrically on both sides of the equidivision points; In step 6, the electric spark drilling is positioned by the inner surface of the conical cylinder blank, the surface positioning clamp in step 5 is used to align the small diameter end face, and the gas film hole is processed according to the drawing requirements; In step 7, the pressing is performed by a punch, and the positioning is performed by the positioning hole in step 5.

2. The precision machining method of the conical segment with convex bundles and dense gas film holes according to claim 1, characterized in that: In step 1, when the conical cylinder blank is prepared, the radial size of the conical cylinder blank is inwardly contracted based on the final required size of the part, the small diameter end and the large diameter end are both extended for a distance along the part surface and then unfolded into a fan-shaped material, the fan-shaped material is divided into two halves after rolling, polishing and positioning welding, and finally the two halves are welded to form a conical cylinder blank, which is ready for use after passing the air tightness check; In step 1, after the conical cylinder blank is welded, the roundness is corrected, and the weld is not allowed to protrude outwardly from the conical cylinder blank.

3. The precision machining method of the conical segment with convex bundles and dense gas film holes according to claim 1, characterized in that: In step 2, the flange is rolled by a two-axis rolling bed, the rollers of the two-axis rolling bed are cylindrical rollers without profile, and the large diameter end of the conical cylinder blank is rolled to form a flange perpendicular to the axis of the conical cylinder blank.

4. The method according to claim 1, wherein the method further comprises the following steps: 4.

1. heating and correcting the shape of the conical segment; 4.

2. cutting the large-diameter end of the conical segment; and 4.

3. cutting the small-diameter end of the conical segment. In step 4, the equipment for heating and correcting the shape is a vacuum heat treatment furnace, and the heating and correcting is performed by using a hot correcting tooling which comprises a convex die and a concave die. The difference between the thermal expansion coefficients of the convex die and the concave die and the thermal expansion coefficient of the part material is used to realize the hot correcting, stabilize the surface profile of the part, and remove the welding stress.

5. The method according to claim 1, wherein: In step 8, the equipment for cutting the large-diameter end is a laser cutting machine, and the inner surface of the conical blank is used for positioning to ensure the outer diameter of the large-diameter end and the height of the conical blank.

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