Method for forming large-size unequal-height lip skin part

Abstract

The invention provides a large-size unequal-height lip skin part forming method, a lip skin part comprises an inner side part and an outer side part, and the method comprises the steps that 1, the outer side double-curvature part of the lip skin part is used for constructing the bottom of a forming cavity structure process molded surface, and the outer side double-curvature part of the lip skin part is used for forming the outer side double-curvature part of the lip skin part; forming the outer side part of the lip skin part through a deep drawing or liquid filling process; step 2, taking the part formed in the step 1 as a process part, cutting redundant process surface plate materials, taking the outer side of the lip skin part formed in the step 1 as a material pressing surface, constructing a process surface with groove characteristics on the inner side of the formed lip skin part, and forming the inner side part of the lip skin part through a deep drawing process, and finally, two-pass forming of the large-size unequal-height lip skin part is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of plastic forming of skin parts with complex curvature, and specifically relates to a forming method of large-sized lip skin parts with unequal heights. Background Art

[0002] With the development of domestic large civil passenger aircraft and transport aircraft, the passenger and load capacity of aircraft has continued to increase. At the same time, in order to increase the aircraft range and reduce fuel consumption, the engine diameter has gradually increased. At present, the overall diameter of the lip parts of domestic engines has reached a maximum of 3.5 meters.

[0003] At the same time, in order to further reduce the air turbulence caused by the step difference between the lip skin and the nacelle skin, the edge of the seam is gradually extended from the high wind speed area to the low wind speed area, that is, the outer edge of the nacelle lip skin is extended in the opposite direction of the heading, resulting in the part height reaching 650-800mm and the inner side height of the lip part reaching 350mm, which further increases the manufacturing difficulty of the part.

[0004] At present, due to the limitations of sheet width, heat treatment equipment, oxidation production lines and other conditions, it is very difficult to achieve the overall forming of 3.5-meter-level lip parts. Therefore, lip parts of this size level are usually formed by dividing them into 3 to 4 petals. Due to the large curvature of the parts and the small opening angle of the parts, the skinning and pulling process cannot be used for forming. There is no experience in forming this type of parts by drop forming, and the surface quality of the parts formed by drop forming is poor and the internal damage is large, which cannot meet the surface and manufacturing accuracy requirements of the parts. Summary of the invention

[0005] Purpose of the invention: In order to meet the requirements of the surface and manufacturing accuracy of parts, this application proposes a stable and low-cost forming method to solve the forming of this type of parts.

[0006] The present application provides a method for forming a large-sized lip skin part with unequal heights, wherein the lip skin part comprises an inner part and an outer part, and the method comprises:

[0007] Step 1: construct the outer hyperbolic part of the lip skin part into the bottom of the molding cavity structure process profile, and form the outer part of the lip skin part by deep drawing or liquid filling process;

[0008] Step 2: Use the part formed in step 1 as a process part, cut the excess process panel material, use the outer side of the lip skin part formed in step 1 as a pressing surface, construct a process surface with groove features on the inner side of the formed lip skin part, and form the inner part of the lip skin part through a deep drawing process.

[0009] Preferably, the step 1 comprises:

[0010] Step 101, adjust the spatial position of the part, cut the lip skin along the ridge line, retain the outer curved surface of the lip, adjust the entire outer curved surface of the lip to be perpendicular to the drawing direction, and keep the height of the two ends consistent along the length direction;

[0011] Step 102, constructing a concave model surface;

[0012] Step 103: construct the convex model surface and the edge-pressing surface.

[0013] Preferably, the step 102 includes:

[0014] The outer circumference of the lip profile after cutting and adjustment is extended by 20mm, and semicircular process profiles are added at both ends in the length direction. The constructed profile is then stretched and rounded in the drawing direction, and the stretching height is about 2-2.5 times the arc length of the inner short side of the lip; the die flange surface is a single curvature profile, and the flange surface and the stretching surface intersect and round.

[0015] Preferably, the step 103 includes:

[0016] The flange surface of the concave model surface is extracted and offset by 1.1 times the material thickness to obtain the blank holding surface. The other surfaces of the concave model surface except the flange surface are offset by 1.1 times the material thickness to obtain the convex model surface.

[0017] Preferably, the step 2 comprises:

[0018] Step 201, constructing the initial sheet material before forming, i.e., the process part;

[0019] Step 202, constructing the lower model surface;

[0020] Step 203, constructing an upper model surface and a pressing surface;

[0021] Step 204: forming the process part into a final lip part state according to the constructed forming die.

[0022] Preferably, the step 201 includes:

[0023] Cut the molded surface after step 1, keep the outer surface of the lip and leave a 100mm margin, keep the stretching surface inside the lip, and keep a 200mm margin on both sides and edges.

[0024] Preferably, the step 202 includes:

[0025] Extract the inner surface of the part, extend the outer circumference of the lip by 200mm, and construct a groove structure with a pressure edge surface on the inner part of the lip based on the stretching surface of the convex model surface in step 1.

[0026] Preferably, the step 203 includes:

[0027] The groove structure of the lower model surface is extracted and the normal offset is 1.1 times the material thickness to obtain the upper model surface. The edge holding surface and the outer side of the lip of the lower model surface are extracted and the normal offset is 1.1 times the material thickness to obtain the pressing surface.

[0028] Beneficial technical effects of this application:

[0029] This application can solve the problem of lip forming parts with a height of 800mm. The overall diameter of the lip parts of domestic engines currently under development reaches a maximum of 3.5 meters, and the lip height reaches 600mm. There is currently no effective process method to achieve low-cost and rapid development of this type of parts. The above-mentioned forming method can effectively solve the forming problem of this type of parts and promote the development of domestic engines.

[0030] The surface quality of the parts is good. The outer surface of the lip is used as the bottom surface of the first step of forming. During the forming process, the sheet metal does not slide relative to the mold, and no scratches will occur on the surface of the parts. The surface quality of the parts after forming is good.

[0031] The manufacturing cost is low. The process methods and processes described in this method all adopt conventional and mature process methods. Compared with some special process methods such as cold mold hot forming, warm mold forming and other process methods, the costs of mold manufacturing, processing process, special process confirmation, etc. have great advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of an aircraft engine lip part provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of a concave model surface provided in an embodiment of the present application;

[0034] Figure 3 A formed process part provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of a lower model surface provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of a forming die structure provided in an embodiment of the present application;

[0037] Among them: 1 lip outer side, 2 lip inner side, 3 ridge line, 4 part edge line, 5 semicircular process surface, 6 flange surface, 7 vertical surface, 8 groove structure, 9 pressing surface, 10 lower die, 11 process part, 12 edge holding die, 13 upper die. DETAILED DESCRIPTION

[0038] The present invention discloses a forming method for a large-sized lip skin part with unequal heights, which is formed twice by constructing different process profiles. In the first step, the outer hyperbolic part of the lip skin part is used to construct the bottom of the process profile of the forming cavity structure, and the outer part of the lip skin part is formed by a deep drawing or liquid filling process. In the second step, the part formed in the first step is used as a process part, the excess process panel material is cut, and the outer side of the lip skin part formed in the first step is used as a pressing surface to construct a process profile with a groove feature on the inner side of the formed lip skin part, and the inner part of the lip skin part is formed by a deep drawing process, and finally the two-pass forming of the large-sized lip skin part with unequal heights is achieved.

[0039] In the embodiment of the present application, a forming method for a large-sized unequal-height lip skin part is provided. The main idea is to form the part in two passes, first forming the outer part of the lip, and then forming the inner part of the lip. Each pass constructs a process profile according to the structural characteristics of the part. The specific steps are as follows:

[0040] 1. Adjust the spatial position of the part, cut the lip skin along the ridge line, retain the outer curved surface of the lip, adjust the entire outer curved surface of the lip to be basically perpendicular to the drawing direction, and keep the height of the two ends basically consistent along the length direction.

[0041] 2. Construct the first step of forming the concave mold surface, extend the outer circumference of the trimmed and adjusted lip by about 20mm, add semicircular process surfaces at both ends in the length direction, and then stretch and round the constructed surface along the drawing direction. The stretching height is about 2-2.5 times the arc length of the inner short side of the lip. The flange surface of the concave mold is a single curvature surface, and the flange surface intersects and rounds with the stretching surface.

[0042] 3. Construct the first step of the convex model surface and the edge holding surface, extract the flange surface of the concave model surface and offset it by 1.1 times the material thickness to obtain the edge holding surface, and the other surfaces of the concave model surface except the flange surface are offset by 1.1 times the material thickness to obtain the convex model surface.

[0043] 4. Construct the initial sheet before the second step of forming, cut the profile after the first step of forming, retain the outer profile of the lip and leave a margin of about 100mm, retain the tensile surface on the inner side of the lip, and leave a margin of about 200mm on both sides and edges.

[0044] 5. Construct the lower model surface in the second step, extract the inner surface of the part, extend the outer part of the lip by 200mm, and construct a groove structure with a pressure edge surface on the inner part of the lip based on the stretching surface of the convex model surface in the first step.

[0045] 6. Construct the second step upper model surface and pressing surface, extract the groove structure of the lower model surface and normal offset 1.1 times the material thickness to obtain the upper model surface, extract the edge pressing surface and the outer side of the lip of the lower model surface and normal offset 1.1 times the material thickness to obtain the pressing surface.

[0046] 7. According to the constructed second step forming die, the process part is formed into the final lip part state.

[0047] Among them, step 2 constructs the first step forming concave model surface, and constructs the outer surface of the lip into the bottom of the first step concave model surface and serves as the right side pressing surface. The vertical surface of the first step concave model surface constructed in step 2 serves as the left side pressing surface.

[0048] Among them, step 2 constructs the first step forming concave model surface, and the height of the vertical surface is about 2-2.5 times the arc length of the inner short side of the lip.

[0049] Among them, step 7 constructs the second step forming concave model surface, which has a groove feature. The left side of the groove structure is consistent with the inner side surface of the lip, and a process margin of about 50 mm is left in the height direction.

[0050] In other embodiments of the present application, a forming method for a large-sized unequal-height lip skin part is provided. The main idea is to form the part in two passes, first forming the outer part of the lip, and then forming the inner part of the lip. Each pass constructs a process profile according to the structural characteristics of the part. The specific steps are as follows:

[0051] 1. Adjust the spatial position of the part, cut the lip skin along the ridge line, retain the outer curved surface of the lip, adjust the entire outer curved surface of the lip to be basically perpendicular to the drawing direction, and keep the height of the two ends basically consistent along the length direction.

[0052] 2. Construct the first step of forming the concave mold surface, extend the outer circumference of the trimmed and adjusted lip by about 20mm, add semicircular process surfaces at both ends in the length direction, and then stretch and round the constructed surface along the drawing direction. The stretching height is about 2-2.5 times the arc length of the inner short side of the lip. The flange surface of the concave mold is a single curvature surface, and the flange surface intersects and rounds with the stretching surface.

[0053] 3. Construct the first step of the convex model surface and the edge holding surface, extract the flange surface of the concave model surface and offset it by 1.1 times the material thickness to obtain the edge holding surface, and the other surfaces of the concave model surface except the flange surface are offset by 1.1 times the material thickness to obtain the convex model surface.

[0054] 4. Construct the initial sheet before the second step of forming, cut the profile after the first step of forming, retain the outer profile of the lip and leave a margin of about 100mm, retain the tensile surface on the inner side of the lip, and leave a margin of about 200mm on both sides and edges.

[0055] 5. Construct the lower model surface in the second step, extract the inner surface of the part, extend the outer part of the lip by 200mm, and construct a groove structure with a pressure edge surface on the inner part of the lip based on the stretching surface of the convex model surface in the first step.

[0056] 6. Construct the second step upper model surface and pressing surface, extract the groove structure of the lower model surface and normal offset 1.1 times the material thickness to obtain the upper model surface, extract the edge pressing surface and the outer side of the lip of the lower model surface and normal offset 1.1 times the material thickness to obtain the pressing surface.

[0057] 7. According to the constructed second step forming die, the process part is formed into the final lip part state.

[0058] In other embodiments of the present application, Figure 1-Figure 5 As shown, in this embodiment, the outer side height of the lip skin part is 650mm, the inner side height is 350mm, the material thickness is 2.5mm, the maximum length of the part is 2600mm, and 2A12 aluminum alloy is selected. The key to this forming method is to construct the first step forming concave model surface and the second step forming lower model surface, and the specific steps are as follows:

[0059] 1. Adjust the spatial position of the part. The lip part is divided into the outer lip 1 and the inner lip 2 according to the ridge line. The lip part surface is cut according to the ridge line to retain the outer lip 1, and the part edge line 4 and the outer edge of the lip are left with a process allowance of 100mm. Adjust the drawing direction of the outer lip 1 to make the drawing height of the part edge line 4 consistent.

[0060] 2. Construct the first concave model surface, construct a semicircular process profile 5 at the end of the part edge line 4, and construct a vertical surface 7 along the drawing direction by combining the curved surface of the lip outer side 1 and the semicircular process profile 5. The flange surface 6 is a single curvature arc surface, and the curvature change is consistent with the curvature change of the lip outer side 1. The distance between the flange surface 6 and the lip outer side 1 and the height of the vertical surface 7 are about 2-2.5 times the arc length of the short side of the lip inner side 2.

[0061] 3. Based on the first step of the concave model surface, the flange surface 6 is extracted and offset by 1.1 times the material thickness (2.75mm) to obtain the blank holder ring, and the surface of the concave model surface other than the flange surface 6 is extracted and offset by 1.1 times the material thickness (2.75mm) to obtain the convex mold. Based on the obtained concave model surface, blank holder ring, and convex model surface, deep drawing or liquid filling forming is performed to obtain a part consistent with the concave model surface.

[0062] 4. The parts formed in the first step are cut with a process allowance, and the outer side of the lip 1 and the vertical surface 7 are retained as process parts 11.

[0063] 5. Construct the second step lower model surface, leave a process allowance around the lip part, and keep the second step lower model surface consistent with the first step concave model surface. Construct a groove structure 8 on the inner side 2 of the lip, the left side of the groove structure 8 is consistent with the inner side 2 of the lip and a process allowance of about 50mm is left in the height direction, the pressing surface 9 is consistent with the vertical surface 7, and the constructed lower model surface is used for the manufacture of the mold 10.

[0064] 6. Based on the lower model surface of the second step, the outer side of the lip 1 and the pressing surface 9 are normally offset by 1.1 times the material thickness (2.75 mm) to construct the edge holding die 12, and the groove structure 8 is normally offset by 1.1 times the material thickness (2.75 mm) to construct the upper die 13.

[0065] 7. Use deep drawing to form the process part 11 into a part consistent with the lower model surface, and finally cut it along the edge line of the lip part to obtain the final lip part.

Claims

1. A method for forming large-sized lip skin parts with different heights, characterized in that: The lip skin part includes an inner portion and an outer portion, and the method includes: Step 1: construct the outer hyperbolic part of the lip skin part into the bottom of the molding cavity structure process profile, and form the outer part of the lip skin part by deep drawing or liquid filling process; Step 2: Use the part formed in step 1 as a process part, cut the excess process panel material, use the outer side of the lip skin part formed in step 1 as a pressing surface, construct a process surface with groove features on the inner side of the formed lip skin part, and form the inner part of the lip skin part through a deep drawing process.

2. The method according to claim 1, characterized in that The step 1 comprises: Step 101, adjust the spatial position of the part, cut the lip skin along the ridge line, retain the outer curved surface of the lip, adjust the entire outer curved surface of the lip to be perpendicular to the drawing direction, and keep the height of the two ends consistent along the length direction; Step 102, constructing a concave model surface; Step 103: construct the convex model surface and the edge-pressing surface.

3. The method according to claim 2, characterized in that The step 102 includes: The outer circumference of the lip profile after cutting and adjustment is extended by 20mm, and semicircular process profiles are added at both ends in the length direction. The constructed profile is then stretched and rounded in the drawing direction, and the stretching height is about 2-2.5 times the arc length of the inner short side of the lip; the die flange surface is a single curvature profile, and the flange surface and the stretching surface intersect and round.

4. The method according to claim 3, characterized in that The step 103 comprises: The flange surface of the concave model surface is extracted and offset by 1.1 times the material thickness to obtain the blank holding surface. The other surfaces of the concave model surface except the flange surface are offset by 1.1 times the material thickness to obtain the convex model surface.

5. The method according to claim 1, characterized in that The step 2 comprises: Step 201, constructing the initial sheet material before forming, i.e., the process part; Step 202, constructing the lower model surface; Step 203, constructing an upper model surface and a pressing surface; Step 204: forming the process part into a final lip part state according to the constructed forming die.

6. The method according to claim 5, characterized in that The step 201 includes: Cut the molded surface formed in step 1, keep the outer surface of the lip and leave a 100mm margin, keep the stretching surface on the inner side of the lip, and keep a 200mm margin on both sides and edges.

7. The method according to claim 6, characterized in that The step 202 includes: Extract the inner surface of the part, extend the outer circumference of the lip by 200mm, and construct a groove structure with a pressure edge surface on the inner part of the lip based on the stretching surface of the convex model surface in step 1.

8. The method according to claim 7, characterized in that The step 203 includes: The groove structure of the lower model surface is extracted and the normal offset is 1.1 times the material thickness to obtain the upper model surface. The edge holding surface and the outer side of the lip of the lower model surface are extracted and the normal offset is 1.1 times the material thickness to obtain the pressing surface.

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