Precision machining method for conical section with convex hulls and dense film holes

Abstract

The invention discloses a precision machining method for a conical section with convex hulls and dense film holes. Comprising the following steps of: preparing a conical cylinder blank, rolling a flange edge, correcting a molded surface of the conical cylinder blank, thermally correcting the profile of the molded surface of the conical cylinder blank, cutting a small-diameter end and a positioning hole of the conical cylinder blank, inflating an air film hole by electric spark, indenting and punching, and processing a large-diameter end of the conical cylinder blank to obtain the outer diameter and the height of the conical cylinder blank. According to the machining method, the same positioning reference and reference transfer are adopted, correction and thermal correction are matched, the dimensional precision of the cone profile and the accurate distance between the convex hull and the concentric small holes and the gas film holes in the convex hull are guaranteed, and the machining efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft engine processing, in particular to a processing method for an aircraft engine cone section with a convex hull and dense air film holes. Background Art

[0002] like Figure 1 The cone section with convex hull and dense air film holes shown in the figure is a hot end part of an aircraft engine. The part is a thin-walled conical cylindrical part with a very high roundness requirement. The surface profile is 0.4mm. There are 6 evenly distributed inwardly concave hulls on the part. There are concentric small holes on the hulls. There are 10 rows of small holes as air film holes at the small diameter end (the diameter of the small holes is ), the holes are evenly distributed, the number of holes in the bottom row is 140, the number of holes in the top row is 50, and the number of holes increases by 10 holes per row, and the hole spacing between the holes in the same row is 10mm. The current processing idea is to weld the sheet into a cone and then manually calibrate the circle, then process the large and small diameter ends, and then process the air film holes, convex hulls and concentric holes. The profile is difficult to guarantee, the manual correction amount is large, the surface quality is poor, and due to the uneven processing end surface, the spacing between the air film holes and the concentric holes on the convex hull cannot be guaranteed. Therefore, it is particularly urgent to study a reasonable and feasible processing method. Summary of the invention

[0003] In view of the problems described in the background technology, the present invention aims to provide a method for precision machining of a cone segment with a convex hull and dense air film holes, thereby improving machining efficiency while improving part quality and pass rate.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for precision machining a cone section with a convex hull and dense air film holes, comprising the following steps:

[0006] Step 1: Prepare the cone blank. The cone blank is processed by sheet metal, cutting the sheet metal into sectors, and then rolling and welding it into the cone blank;

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

[0008] Step 3: Correction: Correct the conical surface of the conical cylinder blank;

[0009] Step 4: Heat calibration to remove the welding stress in step 1 and correct the roundness of the cone blank by heat calibration;

[0010] Step 5: Cut the small diameter end and positioning hole of the cone blank, position and press it according to the profile of the cone blank, cut the small diameter end first, and then move a distance to the large diameter end and cut the positioning hole;

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

[0012] Step 7: Press the dimple and punch the hole. Use the positioning hole in step 5 to position the dimple and then punch the hole.

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

[0014] Specifically, in step 1, when preparing the cone blank, the radial size of the cone blank shrinks inward based on the final required size of the part, and the small diameter end and the large diameter end are extended along the part surface for a distance and then unfolded into a fan-shaped material, and the fan-shaped material is divided into two pieces (halved along the fan-shaped generatrix), rolled, polished, and position welded, and finally the two pieces are welded to form a cone blank, which is used for standby after the airtightness inspection is qualified;

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

[0016] Specifically, in step 2, a two-axis rolling mill is used for rolling the flange edge, and the rollers of the two-axis rolling mill are cylindrical rollers without profiles. The large diameter end of the tapered cylinder blank is rolled over the flange edge, and the flange edge is perpendicular to the axis of the tapered cylinder blank.

[0017] Specifically, in step 3, the correction equipment used is a hydraulic press, and the correction mold has a clamping structure. The correction mold is lifted up and the flange edge is clamped to correct the conical surface of the conical cylinder blank.

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

[0019] Specifically, in step 4, the thermal calibration is carried out using a vacuum heat treatment furnace in conjunction with a thermal calibration tooling, which includes a punch and a die. The thermal calibration is achieved through the difference in thermal expansion coefficients of the punch and die materials and the part material, thereby stabilizing the part surface contour and removing welding stress.

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

[0021] Specifically, in step 5, in the profile positioning fixture for cutting, the positioning surface is the inner profile surface of the cone at the non-hole portion of the cone blank, and the positioning surface is divided into two sections along the axial direction of the cone blank, and there is a gap between the two positioning surfaces;

[0022] Specifically, in step 5, after aligning the axis of the conical cylinder blank, the small diameter end of the conical cylinder blank is cut first, and then at a certain height from the large diameter end of the conical cylinder blank, on the same circular line, with the circumference's equally divided point as the center, a pair of small holes are cut symmetrically on both sides of the equally divided point as positioning holes for subsequent pressing dimples.

[0023] Specifically, in step 6, the electric spark drilling is positioned with the inner surface of the conical cylinder blank, and the surface positioning fixture in step 5 is used to align the end face of the small diameter end, and the air film hole is processed according to the requirements of the drawing.

[0024] Specifically, the device used for pressing the dimple in step 7 is a punch press, which is positioned using the positioning hole in step 5, and the dimple is pressed first and then the hole is punched.

[0025] Specifically, in step 8, the large diameter end is cut using a laser cutting machine, and the inner surface of the conical tube blank is used for positioning to ensure the outer diameter of the large diameter end and the height of the conical tube blank.

[0026] Compared with the prior art, the present invention proposes a precision machining method for a cone section with a convex hull and dense air film holes. Through a reasonable process route and machining method, the same positioning reference and reference transfer are adopted to ensure the dimensional accuracy of the cone surface of the part and the accurate spacing of the convex hull, the concentric small holes on the convex hull and the air film holes, greatly improving the labor efficiency. At present, the machining method has been used on site and has achieved the purpose and requirements of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the front view of the cone section with convex hull and dense air film holes;

[0028] Figure 2 It is a schematic diagram of cutting the small diameter end, cutting the positioning holes and rolling the edges of the cone section with convex hull and dense air film holes. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0030] like Figure 1 and Figure 2 As shown, in this embodiment, a method for precision machining of a cone section with a convex hull and dense air film holes is designed, comprising the following steps:

[0031] Step 1: Prepare the cone blank. The cone blank is processed from sheet metal and laser cut into two identical sector-shaped materials, which are then rolled and welded for subsequent processing (of course, a sector-shaped material can also be directly rolled and welded into a cone blank);

[0032] Step 2: Roll the flange edge. Roll the large diameter end of the cone blank on a two-axis rolling bed to form a flange edge perpendicular to the axis of the cone blank.

[0033] Step 3: Correction: Correct the conical surface of the conical cylinder blank on the correction mold;

[0034] Step 4: Heat correction to remove welding stress and correct the roundness of the cone blank in the heat correction mold;

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

[0036] Step 6: EDM drilling, with the small diameter end as the processing reference, press Figure 1 It is required to punch 10 rows of small holes to form air film holes;

[0037] Step 7: Press the dimple and punch the hole, use the positioning hole cut in step 5 to position, then press the dimple to form a convex hull and then punch the hole to form a concentric small hole;

[0038] Step 8: Process the large diameter end of the cone blank and cut 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 material. The diameter of the cone blank is proportionally shrunk by 1 to 5 mm compared with the final required outer diameter of the part, and the small diameter end is upward along the mold surface ( Figure 1 The small diameter end of the mold extends 5 to 8 mm, and the large diameter end also extends downward along the mold surface ( Figure 1 The cone blank is extended 15 to 20 mm below the large diameter end in the middle, and then the cone blank is unfolded into a fan-shaped material, which is then split into two identical fan-shaped materials and then rolled, polished, tack welded, and argon arc welded to form a cone blank. The cone blank is subjected to an airtight inspection and is ready for use after passing the inspection.

[0040] The roundness of the cone blank prepared in step 1 is corrected to be no greater than 5 after argon arc welding, and the weld is not allowed to bulge, but may be concave, but the concave amount is no greater than the bulging amount during correction in step 3;

[0041] In the above step 2, the flange edge rolling equipment is a two-axis rolling bed, and the roller used is a cylindrical roller without a profile. The large diameter end of the cone blank is rolled over to form a flange edge. The flange edge is perpendicular to the axis of the cone blank, and the flange edge width B is not less than 10 mm.

[0042] In the above step 3, the correction equipment is a hydraulic press, and the correction mold is a stretching mold with a clamping structure. The correction mold lifts the clamping structure to press the flange edge of the conical cylinder blank, and the punch fixed on the lower mold plate is not held. The upper mold plate drives the concave mold and the conical cylinder blank to fall together and fit the forming surface of the punch. Finally, the conical surface of the conical cylinder blank is corrected, and the clamping force is not less than 100T. After correction, the flange edge is allowed to be straightened, that is, the flange edge is stretched and turned over to extend along the conical surface, or the flange edge is corrected to become a part of the conical surface (coplanar);

[0043] In the above step 4, the hot-setting equipment is a vacuum heat treatment furnace, and a special hot-setting tool is used. The cone blank is placed in the gap between the mold surface after the male and female molds are closed and heated. The surface of the male and female molds is consistent with the cone section with convex hull and dense air film holes ( Figure 1 The profile of the conical blank is consistent with that of the conical blank. The difference in thermal expansion coefficient between the convex die and the conical blank material of the hot-setting tooling should be considered. The difference in thermal expansion between the two is used to realize the extrusion setting of the conical blank during the heating and insulation process. The surface profile of the conical blank is stabilized by hot-setting and the welding stress is removed.

[0044] In the above step 5, the equipment used for cutting the small diameter end and the positioning hole is a laser cutting machine, and the surface positioning fixture is used to install and process the cone blank;

[0045] The positioning surface corresponding to the profile positioning fixture used in the above step 5 is the inner profile of the cone at the non-hole portion (i.e., no opening position) on the cone blank. The positioning surface is divided into two sections. The length of each positioning surface (corresponding to the axial length of the cone blank) is not less than 50 mm. The axial distance between the two positioning surfaces is as long as possible to ensure the accuracy of positioning the cone blank.

[0046] In the above step 5, after aligning the axis of the cone blank, first cut the small diameter end of the cone blank to ensure that the size of the small diameter end is D1±0.2mm, and then process the positioning hole at the large diameter end of the part, that is, at a height of (H+5)±0.1mm from the small diameter end. The positioning hole is centered on the Φd1 small hole in the circumferential direction, and two holes are cut at the position with a symmetry line length of 10mm. The small hole serves as the reference positioning hole for subsequent dimple pressing;

[0047] In the above step 6, the equipment used is an electric spark drilling equipment, and the laser cutting end face fixture in step 5 is used for clamping, and the inner surface of the cone blank is positioned to align the small diameter end face, and then the end face is cut according to the laser cutting end face. Figure 1It is required to process 10 exhaust film holes;

[0048] In step 7 above, the denting and punching equipment is a 5000KN punch press, with two Φd1 holes on both sides. Positioning in groups, first pressing dimples and then punching holes, ensuring the depth of the dimples and the diameter of the concentric holes;

[0049] In the above step 8, the large diameter end is cut by a laser cutting machine, and the cone inner surface of the cone blank is also used for positioning. After clamping with the same surface positioning fixture as in step 5, the large diameter end is cut (including removing the flange edge) to ensure Figure 1 The size D2±0.2mm of the large diameter end and the height H of the tapered blank are shown in FIG.

[0050] by Figure 1 As an example, take the dimensions shown in the figure, take D1 = Φ46mm, D2 = Φ287mm, H = 187mm, L = 20.3mm, Φd = Φ0.8mm, Φd1 = Φ6mm, the precision machining method of the cone section with convex hull and dense air film hole is as follows:

[0051] Step 1: Prepare the cone blank. Figure 1 The cone section with convex hull and dense air film holes in the middle is proportionally reduced by 4mm in radial direction, the small diameter end is extended by 8mm, and the large diameter end is extended by 20mm. It is unfolded into a fan-shaped material and cut into two identical fan-shaped pieces. After rolling and welding into a cone blank, the roundness is manually corrected to no more than 5mm. The weld is not allowed to be convex outward, and the concave is allowed to be no more than 1.5mm.

[0052] Step 2: Roll the flange edge. Roll the large diameter end of the cone blank on a two-axis rolling bed to form a flange edge perpendicular to the axis of the cone blank. The width of the flange edge is 13mm.

[0053] Step 3: Correction: Press the flange edge on the correction die to correct the conical surface of the conical cylinder blank, allowing the roundness of the part to be no more than 3mm in the free state;

[0054] Step 4: Heat calibration to remove welding stress. At the same time, the surface profile of the cone blank is not more than 0.4mm in the heat calibration mold to stabilize the surface dimensional accuracy.

[0055] Step 5: Cut the small diameter end and positioning holes. Position the inner surface on the laser cutting equipment, press the outer surface, cut the small diameter end, ensure the diameter size, and move down 192±0.1mm at the same time. Two small holes are a group. Cut 6 groups of positioning holes evenly distributed along the circumference. The circumferential center distance of the small holes is 10±0.2, and the hole diameter is

[0056] Step 6: EDM drilling, locate the inner surface of the cone blank, align the small diameter end and the central axis of the cone blank perpendicularly, take the small diameter end as the processing reference, press Figure 1 As shown, n rows of i Φ0.8 mm small holes are punched as air film holes;

[0057] Step 7: Press and punch holes to Position the small hole, press the dimple and punch the hole on the punch press, it is required to press the dimple first and then punch the Φ6mm small hole;

[0058] Step 8: Process the large diameter end, position it on the laser cutting machine with the inner surface of the cone blank, press the outer surface, cut the large diameter end, and ensure the size is Φ287±0.2mm and the height is 187mm.

[0059] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A precision machining method for a cone section with a convex hull and dense air film holes, characterized in that: The following steps are involved: Step 1: Prepare the cone blank. The cone blank is processed by sheet metal, cutting the sheet metal into sectors, and then rolling and welding it into the cone blank; Step 2: Roll the flange edge. Roll the large diameter end of the cone blank on a two-axis rolling bed to form a flange edge perpendicular to the axis of the cone blank. Step 3: Correction: Correct the conical surface of the conical cylinder blank; Step 4: Heat calibration to remove the welding stress in step 1 and correct the roundness of the cone blank by heat calibration; Step 5: Cut the small diameter end and positioning hole of the cone blank, position and press it according to the profile of the cone blank, cut the small diameter end first, and then move a distance to the large diameter end and cut the positioning hole; Step 6: Electric spark drilling, taking the small diameter end of the cone blank as the processing reference, use electric spark drilling to process the air film hole according to the requirements of the drawing; Step 7: Press the dimple and punch the hole, and then punch the hole after positioning the dimple with the positioning hole in step 5; Step 8: Cut the large diameter end to obtain the required outer diameter and height dimensions.

2. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In the step 1, when preparing the cone blank, the radial dimension of the cone blank shrinks inward based on the final required dimension of the part, and the small diameter end and the large diameter end are extended along the part profile for a distance and then unfolded into a fan-shaped material, the fan-shaped material is divided into two pieces, then rolled, polished, and position welded, and finally the two pieces are welded to form the cone blank, and the blank is used for standby after the airtightness inspection is qualified; In the step 1, after the cone barrel blank is welded, the roundness is corrected, and the weld is not allowed to protrude to the outside of the cone barrel blank.

3. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 2, a two-axis rolling machine is used for rolling the flange edge, and the rollers of the two-axis rolling machine are cylindrical rollers without profiles. The large diameter end of the cone blank is rolled over the flange edge, and the flange edge is perpendicular to the axis of the cone blank.

4. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In the step 3, the correction equipment is a hydraulic press, and the correction mold has a edge pressing structure. The correction mold is lifted up and the flange edge is pressed to correct the conical surface of the conical cylinder blank.

5. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 3, the flange edge forms a part of the large-diameter end conical surface of the conical cylinder blank during the correction process.

6. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 4, the thermal calibration is carried out using a vacuum heat treatment furnace in combination with a thermal calibration tool. The thermal calibration tool includes a punch and a die. The thermal calibration is achieved by using the difference in thermal expansion coefficients of the punch and die materials and the part material to stabilize the part surface profile and remove welding stress.

7. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 5, the small diameter end and the positioning hole are cut using a laser cutting machine, and a profile positioning fixture is used for installation and processing; In the step 5, in the profile positioning fixture for cutting, the positioning surface is the inner profile surface of the cone at the non-hole portion of the cone blank, and 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 of the positioning surface; In the step 5, after aligning the axis of the conical cylinder blank, the small diameter end of the conical cylinder blank is cut first, and then at a height away from the large diameter end of the conical cylinder blank, on the same circular line, with the circumference equally divided point as the center, a pair of small holes are cut symmetrically on both sides of the equally divided point as positioning holes for subsequent pressing dimples.

8. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 6, the electric spark drilling is positioned with the inner profile of the conical cylinder blank, and the profile positioning fixture in step 5 is used to align the end face of the small diameter end, and the air film hole is processed according to the requirements of the drawing.

9. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: The device used for pressing the dimple in step 7 is a punch press, which is positioned by the positioning hole in step 5, and the dimple is pressed first and then the hole is punched.

10. The method for precision machining of a cone section with a convex hull and dense air film holes according to claim 1, characterized in that: In step 8, the large diameter end is cut using a laser cutting machine, and the inner surface of the cone blank is used for positioning to ensure the outer diameter of the large diameter end and the height of the cone blank.

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