A forming method of a large-size unequal-height lip skin part

Abstract

The application provides a forming method of a large-size unequal-height lip skin part, the lip skin part comprising an inner side part and an outer side part, and the method comprises the following steps: step 1, configuring an outer side hyperbolic part of the lip skin part as a bottom of a cavity structure process surface, and forming the outer side part of the lip skin part through deep drawing or liquid filling process; and step 2, taking the part formed in step 1 as a process part, cutting the excess process surface plate material, taking the outer side of the lip skin part formed in step 1 as a pressing surface, configuring a process surface with groove features of the inner side of the formed lip skin part, and forming the inner side part of the lip skin part through deep drawing process, so as to finally realize two-pass forming of the large-size unequal-height lip skin part.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plastic forming of complex curvature skin parts, and particularly relates to a forming method for large-size unequal-height lip skin parts. BACKGROUND

[0002] With the development of domestic large civil aircraft and transport aircraft, the passenger and load capacity of the aircraft is continuously increasing. In order to improve the aircraft range and reduce fuel consumption, the diameter of the engine is gradually increased. At present, the overall diameter of the domestic engine lip part reaches 3.5 meters.

[0003] At the same time, in order to further reduce the air turbulence phenomenon caused by the butt joint step difference of 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 reversely elongated to the heading direction, resulting in that the height of the part reaches 650-800 mm, the inner height of the lip part reaches 350 mm, and the manufacturing difficulty of the part is further increased.

[0004] At present, due to the limitations of sheet width, heat treatment equipment, oxidation production line and other conditions, it is difficult to realize the overall forming of the 3.5-meter-level lip part, so the lip part of this size level is usually formed into 3-4 petals. Due to the large curvature of the part and the small opening angle of the part, the skin drawing process cannot be used for forming. There is no experience in forming this type of part by using the drop press forming, and the surface quality of the part formed by using the drop press forming is poor and the internal damage is large, which cannot meet the surface and manufacturing precision requirements of the part. SUMMARY

[0005] The application aims to meet the surface and manufacturing precision requirements of the part, and provides a stable and low-cost forming method to solve the forming of the part.

[0006] The application provides a forming method for a large-size unequal-height lip skin part. The lip skin part comprises an inner side part and an outer side part. The method comprises the following steps:

[0007] Step 1: forming the outer side double curvature part of the lip skin part into the bottom of a cavity structure process surface, and forming the outer side part of the lip skin part by deep drawing or liquid filling process;

[0008] Step 2: taking the part formed in step 1 as a process part, cutting the excess process surface sheet, taking the outer side of the lip skin part formed in step 1 as a pressing surface, constructing a process surface with groove characteristics for forming the inner side of the lip skin part, and forming the inner side part of the lip skin part by deep drawing process.

[0009] Preferably, the step 1 comprises the following steps:

[0010] Step 101, adjust the part space position, cut the lip skin along the ridge line, keep the lip outside curve, adjust the entire lip outside curve to be perpendicular to the drawing direction, keep the height of both ends consistent in the length direction;

[0011] Step 102, construct the concave model surface;

[0012] Step 103, construct the convex model surface and the blank holder surface.

[0013] Preferably, the step 102 comprises:

[0014] The cut and adjusted lip outside profile is extended by 20mm in excess outside the circle, the length direction both ends are supplemented with semicircular process profiles, and the constructed profile is stretched and rounded in the drawing direction, with the stretching height being about 2-2.5 times the arc length of the lip inside short side; the concave die flange surface is a single curvature profile, and the flange surface is rounded when intersecting with the stretching surface.

[0015] Preferably, the step 103 comprises:

[0016] The blank holder surface is obtained by offsetting the flange surface of the concave die model surface by 1.1 times the material thickness, and the convex model surface is obtained by offsetting the remaining profile of the concave die model surface by 1.1 times the material thickness.

[0017] Preferably, the step 2 comprises:

[0018] Step 201, construct the initial plate before forming, i.e. the process piece;

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

[0020] Step 203, construct the upper model surface and the blank holder surface;

[0021] Step 204, form the process piece into the final lip part state according to the constructed forming die.

[0022] Preferably, the step 201 comprises:

[0023] The profile after forming in step 1 is cut, the lip outside profile is kept and 100mm excess is left, the lip inside stretching surface is kept, and both sides and edges keep 200mm excess.

[0024] Preferably, the step 202 comprises:

[0025] The part inner surface is extracted, the lip outside part is extended by 200mm excess outside the circle, and the lip inside part is constructed to have a recess structure with a blank holder surface based on the stretching surface of the convex model surface in step 1.

[0026] Preferably, the step 203 comprises:

[0027] The upper model surface is obtained by extracting the groove structure of the lower model surface and offsetting it by 1.1 times the material thickness in the normal direction. The blank holder surface and the outer side of the lip of the lower model surface are extracted and offset by 1.1 times the material thickness in the normal direction to obtain the pressure surface.

[0028] The beneficial technical effects of the present application are:

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

[0030] The surface quality of the part is good. The outer side profile of the lip is used as the bottom surface of the first forming. During the forming process, the sheet metal does not slide relative to the mold, and the surface of the part will not be scratched. The surface quality of the formed part is good.

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

[0032] Figure 1 An aero-engine lip part is provided for the embodiments of the present application;

[0033] Figure 2 A concave model surface is provided for the embodiments of the present application;

[0034] Figure 3 A formed workpiece is provided for the embodiments of the present application;

[0035] Figure 4 A lower model surface is provided for the embodiments of the present application;

[0036] Figure 5 A forming mold structure is provided for the embodiments of the present application;

[0037] Wherein: 1 lip outer side, 2 lip inner side, 3 ridge line, 4 part edge line, 5 semicircular process profile, 6 flange surface, 7 vertical surface, 8 groove structure, 9 pressure surface, 10 lower mold, 11 workpiece, 12 blank holder mold, 13 upper mold. DETAILED DESCRIPTION

[0038] The application discloses a forming method for a large-size unequal-height lip skin part, which is formed by constructing different process surfaces twice. In the first step, the outer hyperbolic part of the lip skin part is constructed as the bottom of a cavity structure process surface, and the outer part of the lip skin part is formed by deep drawing or liquid filling process. In the second step, the part formed in the first step is taken as a process part, the excess process surface plate material is cut, the outer side of the lip skin part formed in the first step is taken as a pressing surface, a process surface with a groove feature forming the inner side of the lip skin part is constructed, and the inner side of the lip skin part is formed by deep drawing process, so that the two-pass forming of the large-size unequal-height lip skin part is finally realized.

[0039] In the embodiment of the application, a forming method for a large-size unequal-height lip skin part is provided, and the main idea is to form the part in two passes, form the outer side of the lip first, and then form the inner side of the lip. The process surface is constructed according to the structure features of the part in each pass, and the specific steps are as follows.

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

[0041] 2. Construct the first forming concave die surface, extend the outer side surface of the cut and adjusted lip by about 20 mm, supplement the semicircular process surface at the two ends in the length direction, stretch the constructed surface in the deep drawing direction, and round the stretched part, and the stretching height is about 2-2.5 times the arc length of the short side of the inner side of the lip. The flange surface of the concave die is a single-curvature surface, and the flange surface and the stretched surface are rounded.

[0042] 3. Construct the first forming convex die surface and the blank holder surface, offset the flange surface of the concave die surface by 1.1 times the thickness of the material to obtain the blank holder surface, and offset the remaining surface of the concave die surface by 1.1 times the thickness of the material to obtain the convex die surface.

[0043] 4. Construct the initial plate before the second forming, cut the surface formed in the first step, keep the outer side surface of the lip and leave a surplus of about 100 mm, keep the stretched surface of the inner side of the lip, and keep the surplus of about 200 mm at the two sides and the edge.

[0044] 5. Construct the lower die surface of the second step, extract the inner surface of the part, extend the outer side surface of the lip by about 200 mm, and construct the groove structure with the blank holder surface based on the stretched surface of the convex die surface of the first step.

[0045] 6. Construct the upper die surface and the pressing surface of the second step, offset the groove structure of the lower die surface by 1.1 times the thickness of the material to obtain the upper die surface, and offset the blank holder surface and the outer side of the lip of the lower die surface by 1.1 times the thickness of the material to obtain the pressing surface.

[0046] 7. Form the process piece into the final lip part state according to the second step forming die structure.

[0047] Wherein, step 2 constructs the first step forming concave die surface, the lip outer side profile is constructed as the bottom of the first step concave die surface and as the right side blanking surface, and the vertical surface of the first step concave die surface is constructed as the left side blanking surface.

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

[0049] Wherein, step 7 constructs the second step forming concave die surface, which has a groove structure, the left side of the groove structure is consistent with the lip inner side profile, and there is a process allowance of about 50 mm in the height direction.

[0050] In other embodiments of the present application, a forming method for a large-size unequal-height lip skin part is provided, which mainly adopts a two-pass forming method, i.e., first forming the lip outer side part and then forming the lip inner side part. Each pass is constructed according to the structural characteristics of the part, and 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 lip outer side curved surface, adjust the entire curved surface of the lip outer side to be substantially perpendicular to the drawing direction, and keep the height of the two ends in the length direction substantially consistent.

[0052] 2. Construct the first step forming concave die surface, extend the lip outer side profile after cutting and adjusting by about 20 mm of excess outside the circumference, supplement the semicircular process profile at the two ends in the length direction, then stretch and round the constructed profile in the drawing direction, and the stretching height is about 2-2.5 times the arc length of the short side of the lip inner side. The concave die flange surface is a single curvature profile, and the flange surface is rounded at the intersection with the stretching surface.

[0053] 3. Construct the first step convex die surface and the blank holder surface, offset the flange surface of the concave die surface by 1.1 times the material thickness to obtain the blank holder surface, and offset the remaining profile of the concave die surface by 1.1 times the material thickness to obtain the convex die surface.

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

[0055] 5. Construct the second step lower die surface, extract the inner surface of the part, extend the lip outer side part by 200 mm of excess outside the circumference, and construct the groove structure with a blank holder surface based on the stretching surface of the first step convex die surface.

[0056] 6. Construct the upper model surface and the pressing surface in the second step. Extract the groove structure of the lower model surface and offset it normally by 1.1 times the material thickness to obtain the upper model surface. Extract the pressing surface and the outer side of the lip of the lower model surface and offset it normally by 1.1 times the material thickness to obtain the pressing surface.

[0057] 7. Using the second-step forming mold constructed, shape the workpiece to the final lip part state.

[0058] In other embodiments of this application, such as Figures 1-5 As shown, in this embodiment, the outer height of the lip skin part is 650mm, the inner 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 lies in constructing the first-step forming concave mold surface and the second-step forming lower mold surface. The specific steps are as follows:

[0059] 1. Adjust the spatial position of the parts. The lip part is divided into outer lip 1 and inner lip 2 according to the ridge line. Cut the lip part surface according to the ridge line, retaining outer lip 1. Leave a 100mm process allowance for the part edge line 4 and the outer edge of the lip. Adjust the drawing direction of outer lip 1 to make the drawing height of part edge line 4 consistent.

[0060] 2. Construct the first concave model surface. At the end of the part edge line 4, construct a semi-circular process surface 5. The curved surface where the outer lip 1 meets the semi-circular process surface 5 is constructed along the drawing direction to form a vertical surface 7. The flange surface 6 is a single-curvature arc surface, with its curvature variation consistent with that of the outer lip 1. The distance between the flange surface 6 and the outer lip 1, and the height of the vertical surface 7, are approximately 2-2.5 times the arc length of the shorter side of the inner lip 2.

[0061] 3. Based on the concave mold surface from step one, extract flange surface 6 by offsetting it normally by 1.1 times the material thickness (2.75mm) to obtain the blank holder. Extract the other surfaces of the concave mold surface (excluding flange surface 6) by offsetting them normally by 1.1 times the material thickness (2.75mm) to obtain the punch. Based on the obtained concave mold surface, blank holder, and punch surface, perform deep drawing or liquid filling forming to obtain a part consistent with the concave mold surface.

[0062] 4. Cut the parts formed in the first step and leave a process allowance, retaining the outer lip 1 and the vertical surface 7 as the process part 11.

[0063] 5. Construct the second lower model surface, leaving a process allowance around the lip part. The second lower model surface is consistent with the first 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 blank holder surface 9 is consistent with the vertical surface 7. The constructed lower model surface is used for the manufacturing of mold 10.

[0064] 6. Based on the second step lower die surface, the lip outer side 1 and the pressure surface 9 are offset by 1.1 times the material thickness (2.75 mm) to form the blank holder 12, and the groove structure 8 is offset by 1.1 times the material thickness (2.75 mm) to form the upper die 13.

[0065] 7. The workpiece 11 is formed into a part conforming to the lower die surface by deep drawing, and finally cut along the edge line of the lip part to obtain the final lip part.

Claims

1. A method of forming a large scale unequal height lip skin part, characterized by, The lip skin part comprises an inner side portion and an outer side portion, and the method comprises: Step 1, configuring the outer side hyperbolic portion of the lip skin part as the bottom of the cavity structure process surface, and forming the outer side portion of the lip skin part through deep drawing or liquid filling process; Step 2, taking the part formed in step 1 as the process part, cutting the excess process surface plate material, taking the outer side of the lip skin part formed in step 1 as the pressure surface, configuring the process surface with the groove feature of the inner side of the formed lip skin part, and forming the inner side portion of the lip skin part through deep drawing process; The step 1 comprises: Step 101, adjusting the spatial position of the part, cutting the lip skin along the ridge line, retaining the outer side curve of the lip, and adjusting the entire curve of the outer side of the lip to be perpendicular to the deep drawing direction, and keeping the height of the length direction both ends consistent; Step 102, configuring the concave model surface; Step 103, configuring the convex model surface and the blank holder surface; The step 102 comprises: Extending the outer side surface of the cut and adjusted lip by 20mm, supplementing the semicircular process surface at the length direction both ends, and then stretching the formed surface along the deep drawing direction to round off, and the stretching height is 2-2.5 times the arc length of the short side of the inner side of the lip; the flange surface of the concave die is a single curvature surface, and the flange surface is rounded off at the intersection with the stretching surface; The step 103 comprises: Extracting the blank holder surface by offsetting the flange surface of the concave model surface by 1.1 times the material thickness in the normal direction to obtain the convex model surface, and offsetting the remaining surface of the concave model surface by 1.1 times the material thickness in the normal direction to obtain the convex model surface; The step 2 comprises: Step 201, configuring the initial plate before forming, i.e. the process piece; Step 202, configuring the lower model surface; Step 203, configuring the upper model surface and the pressure surface; Step 204, forming the process piece to the final lip part state according to the configured forming die; The step 201 comprises: Cutting the surface formed after step 1, retaining the outer side surface of the lip and leaving a 100mm excess, retaining the stretching surface of the inner side of the lip, and retaining a 200mm excess on both sides and edges; The step 202 comprises: Extracting the inner surface of the part, extending the outer side portion of the lip by 200mm, and configuring the groove structure with the blank holder surface based on the stretching surface of the convex model surface of step 1; The step 203 comprises: Extracting the groove structure of the lower model surface and offsetting by 1.1 times the material thickness in the normal direction to obtain the upper model surface, and extracting the blank holder surface of the lower model surface and the outer side of the lip and offsetting by 1.1 times the material thickness in the normal direction to obtain the pressure surface.

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