Multi-degree-of-freedom point enveloping forming method for thin-walled high-rib aircraft wing rib

Abstract

The present application relates to a kind of thin-walled high rib aircraft wing rib multi-degree-of-freedom point envelope forming method, and the forming device used includes spherical envelope die, die, rectangular slab, blank holder and top block;Thin-walled high rib aircraft wing rib multi-degree-of-freedom point envelope forming method includes the following steps: S1, rectangular slab is placed in die;S2, drive spherical envelope die to complete multiple cycles of broken line type trajectory multi-degree-of-freedom point envelope movement, until die pushes rectangular slab to feed upwards to the distance set;Rectangular slab occurs continuous local large plastic deformation under the joint action of spherical envelope die and die, and the cavity surface of spherical envelope model cavity surface is collectively enveloped to form aircraft wing rib high rib profile at different time, finally realize thin-walled high rib aircraft wing rib one-time overall forming, obtain aircraft wing rib forge piece;S3, top block ejects forge piece from the cavity of die, realizes the separation of forge piece and die.The present application can realize one-time overall forming manufacturing of aircraft wing rib, and can greatly improve manufacturing efficiency and material utilization.

Description

Technical Field

[0001] This invention relates to the field of aircraft wing rib forming and manufacturing technology, and more specifically, to a method for multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs. Background Technology

[0002] Thin-walled, highly stiffened structural members are lightweight, rigid, strong, and have high load-bearing capacity, making them key load-bearing structures widely used in aerospace equipment. Aircraft wing ribs are typical examples of thin-walled, highly stiffened structural members, characterized by large dimensions, thin webs, and complex highly stiffened structures. They are made of high-strength aluminum alloy, which has high strength and low plasticity. The extreme geometry and difficult-to-machine characteristics of the material make the manufacture of aircraft wing ribs extremely challenging. Current manufacturing processes for aircraft wing ribs involve milling. Milling cannot refine the grain structure or cut off metal flow lines, resulting in localized material damage and poor surface integrity. Furthermore, it is inefficient, has low material utilization, and is costly, severely reducing the load-bearing capacity and lightweighting level of aircraft wing ribs, and failing to meet the high-performance, high-efficiency, and low-cost manufacturing requirements of next-generation aircraft wing ribs.

[0003] If an integral die forging process is used to form aircraft wing ribs, the material has great resistance to metal flow, making it very difficult to fill the high-rib section. Rigid impacts will occur between the dies, and the load conditions of the dies and forming equipment will be very harsh, which will significantly reduce the service life of the dies and equipment. Therefore, the integral die forging process is difficult to achieve plastic forming of thin-walled high-rib aircraft wing ribs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs, which can realize the one-time integral forming and manufacturing of aircraft wing ribs, and can greatly improve manufacturing efficiency and material utilization.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs is constructed. The multi-degree-of-freedom point envelope forming device includes a spherical envelope mold, a concave mold, a rectangular blank, a pressure plate, and a top block. The multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs includes the following steps:

[0006] S1. Place the rectangular blank in the cavity mold, with the lower surface of the rectangular blank in contact with the bottom surface of the cavity mold. Install a pressure plate above the cavity mold, with the pressure plate in contact with the upper surface of the rectangular blank and fixing the rectangular blank in the cavity mold. Install a spherical enveloping mold above the rectangular blank, with the cavity surface of the spherical enveloping mold in contact with the upper surface of the rectangular blank.

[0007] S2. First, move the spherical enveloping mold to the long side l of the rear of the rectangular slab. a Above one vertex, the concave die pushes the rectangular blank upwards a distance s, causing the spherical enveloping die to press into the rectangular blank; the spherical enveloping die is driven along the long side l.a Move to the other vertex of the long side, and then move along the path that intersects with the long side l. a Move diagonally forward at an angle θ to the opposite short side, then move along the long side l. a The spherical enveloping mold moves obliquely forward at an angle of π-θ to the other short side, repeating the above movement until it reaches the front long side l of the rectangular slab. b Until the vertex; thereafter continue driving the spherical envelope mold along the long side l of the front side of the rectangular slab. b Move to the other vertex of the long side, and then move along the path that intersects with the long side l. b Move diagonally backward at an angle θ to the opposite short side, then move towards the long side l. b The spherical enveloping die continues to move obliquely backward in the π-θ direction to the other short side, repeating the above movement until the spherical enveloping die moves to the initial position, completing one cycle of multi-degree-of-freedom point enveloping motion of a broken line trajectory; the spherical enveloping die is driven to complete multiple cycles of multi-degree-of-freedom point enveloping motion of a broken line trajectory according to the above rules, until the die pushes the rectangular slab upward to the set distance S; under the combined action of the spherical enveloping die and the die, the rectangular slab undergoes continuous local large plastic deformation, the metal flows in multiple directions and continuously fills the high-rib cavity of the spherical enveloping die, the rectangular slab gradually thins while the high rib gradually grows, and at different times the cavity surface of the spherical enveloping die together envelops and forms the high-rib surface of the aircraft wing rib, finally realizing the one-time integral forming of the thin-walled high-rib aircraft wing rib, and obtaining the aircraft wing rib forging;

[0008] S3. Drive the die cavity downward to gradually separate the forging from the spherical enveloping die; remove the pressure plate and use the ejector block arranged in the die cavity to eject the forging from the die cavity, thus separating the forging from the die cavity.

[0009] 2. The method for forming thin-walled, high-rib aircraft wing ribs using multi-degree-of-freedom point envelope as described in claim 1, characterized in that, in step S2, during the multi-degree-of-freedom point envelope motion of the spherical envelope mold, the spherical envelope mold always rolls purely along a polygonal trajectory on the surface of the rectangular slab; the number of polygonal segments traversed by the spherical envelope mold during one cycle of multi-degree-of-freedom point envelope motion along a polygonal trajectory is n, where n and θ satisfy the following relationship:

[0010]

[0011] In the formula, a is the length of the long side of the rectangular slab; b is the length of the short side of the rectangular slab; and n is an integer.

[0012] In the above scheme, the spherical envelope mold is used to form the high-rib profile of aircraft wing rib forgings. The design method of the cavity surface of the spherical envelope mold includes the following steps:

[0013] S41. Establish a coordinate system O-xyz with a straight line perpendicular to the upper surface of the rectangular slab and passing through the geometric center of the rectangular slab as the z-axis, the intersection of the z-axis and the upper surface of the rectangular slab as the origin O, and a straight line passing through the origin O and parallel to the length direction of the rectangular slab as the x-axis.

[0014] S42. The high-rib surface of the thin-walled high-rib aircraft wing rib component is discretized into a point cloud. Under the coordinate system established in step S41, the coordinates of all points in the point cloud are obtained. The coordinate transformation is performed by the coordinate transformation formula (1) to form a spherical envelope model surface point cloud.

[0015]

[0016] In the formula, (x,y,z) are the coordinates of any point in the point cloud of the high-rib profile of the thin-walled high-rib aircraft wing, (x′,y′,z′) are the coordinates of the spherical envelope module point corresponding to point (x,y,z), R is the radius of the spherical envelope module, and i=1,2,…,n;

[0017] S43 and S42: The point cloud of the spherical envelope model surface is fitted into a curved surface to obtain the spherical envelope model cavity surface for multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs.

[0018] The design method for the aircraft wing rib forgings in the above scheme includes:

[0019] The high-rib section of the thin-walled high-rib aircraft wing rib consists of five short ribs and two long ribs. Based on the dimensions of the aircraft wing rib parts, a machining allowance of 1-2 mm is added to both the high rib and the web surface of the aircraft wing rib. A draft angle of 2°-5° is added to the side of the high rib. First, longitudinal flash is designed around the web, and then transverse flash is designed at the top of the longitudinal flash, forming a stepped flash structure for the aircraft wing rib forging. The web is extended 10-15 mm in all directions to form a pressure flash, which is used to constrain the forging in the die cavity through the pressure plate to prevent the forging from warping and deforming.

[0020] In the above scheme, the outer contour of the pressure plate is consistent with the outer contour of the die, and the inner contour is consistent with the outer contour of the longitudinal flash of the forging. The pressure plate is divided into two halves along the center line of the width direction of the pressure plate to form a split pressure plate that facilitates demolding of the forging.

[0021] In the above scheme, a top block is set in the cavity. The top block is located below the short rib of the forged aircraft wing rib after forming. The top block is rectangular in shape, with its width consistent with the width of the short rib of the forging, its length less than the length of the short rib of the forging, and its thickness 5-10 mm thicker than the cavity of the cavity.

[0022] The multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs of the present invention has the following beneficial effects:

[0023] 1. The thin-walled, high-rib aircraft wing rib multi-degree-of-freedom point envelope forming method of the present invention can realize the one-time integral forming manufacturing of aircraft wing ribs, which can greatly improve manufacturing efficiency and material utilization, while obtaining fine grains and conformal continuous metal flow lines, thereby greatly improving the load-bearing capacity and fatigue life of aircraft wing ribs.

[0024] 2. In the multi-degree-of-freedom point envelope forming method for thin-walled high-rib aircraft wing ribs of the present invention, the spherical envelope mold and the aircraft wing rib are in point contact, which results in low forming force and low energy consumption. It can realize the forming and manufacturing of thin-walled high-rib aircraft wing ribs with small tonnage equipment.

[0025] 3. In the multi-degree-of-freedom point envelope forming method for thin-walled high-rib aircraft wing ribs of the present invention, the spherical envelope mold and the aircraft wing rib are in point contact, and the envelope mold performs multi-degree-of-freedom flexible motion, which can realize active control of metal flow, thereby realizing active control of thinning of the web of the aircraft wing rib and high-rib growth, ensuring the forming quality and forming accuracy of the aircraft wing rib. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0027] Figure 1 A schematic diagram of the structure of a thin-walled, high-rib aircraft wing component;

[0028] Figure 2 A schematic diagram of a thin-walled, high-rib aircraft wing forging structure;

[0029] Figure 3 This is a schematic diagram of the coordinate transformation of the module points of the spherical envelope;

[0030] Figures 4-5 A diagram of a spherical envelope model;

[0031] Figure 6 This is a schematic diagram of the polygonal trajectory of a spherical envelope model.

[0032] Figure 7 Schematic diagram of a thin-walled, high-ribbed aircraft wing rib pressure plate;

[0033] Figure 8 This is an assembly drawing of the forming mold and blank for thin-walled, high-rib aircraft wing;

[0034] Figure 9 A schematic diagram of the multi-degree-of-freedom point envelope forming process of thin-walled, high-rib aircraft wing ribs;

[0035] Figure 10 A comparison diagram of the forming forces of single-degree-of-freedom die forging and multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs;

[0036] Figure 11 A comparison diagram of the theoretical design rib height and the rib height of multi-degree-of-freedom point envelope forming for thin-walled, high-rib aircraft wing. Detailed Implementation

[0037] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] The aircraft wing rib member studied in this example has external dimensions of 740mm in length, 180mm in width, 1.27mm in web thickness, and 2mm in rib thickness. Figure 1 As shown. A high-performance, high-efficiency, multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs includes the following steps:

[0039] S1. Forging Design: Based on the dimensions of the aircraft wing rib parts, a 2mm machining allowance is added to the upper and lower surfaces of the web, and a 2mm machining allowance is added to both sides of the high rib. A 3° draft angle is set on each vertical surface of the forging, and a flash structure is added to the edge of the web, with a flash thickness of 2mm and a longitudinal flash height of 8mm. Because the aircraft wing rib is large and the web is thin, warping deformation is prone to occur during local loading of the spherical envelope die. To prevent warping, the circumferential width of the aircraft wing rib web needs to be increased by 10mm for blank holders, such as... Figure 2 As shown;

[0040] S2. Spherical Envelope Mold Design: The spherical envelope mold is used to form the high rib section of aircraft wing rib forgings. The design steps for the cavity surface of the spherical envelope mold are as follows:

[0041] S21. Establish a coordinate system O-xyz with the straight line perpendicular to the upper surface of the rectangular slab and passing through the geometric center of the rectangular slab as the z-axis, the intersection of the z-axis and the upper surface of the rectangular slab as the origin O, and the straight line passing through the origin O and parallel to the length direction of the rectangular slab as the x-axis.

[0042] S22. Discretize the inner stiffened surface of the thin-walled, high-rib aircraft wing rib component into a point cloud. Obtain the coordinates of all points in the point cloud under the coordinate system established in step S11, and transform them using the coordinate transformation formula (1).

[0043]

[0044] In the formula, (x, y, z) represents the coordinates P of any point in the point cloud of the inner ribbed surface of a thin-walled, high-ribbed aircraft wing, and (x′, y′, z′) represents the coordinates P′ of the upper mold point corresponding to point (x, y, z). Figure 3 As shown, R is the required radius of the sphere, where i = 1, 2, ..., n; the final transformed point cloud coordinates can be obtained from the above relationship;

[0045] S23. Fit the point cloud data obtained in step S22 into a curved surface to obtain a spherical envelope mold for multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs, such as... Figures 4-5 As shown;

[0046] S3. Trajectory Design Method: The spherical envelope mold performs a pure rolling motion in a zigzag pattern on the upper surface of the rectangular slab. The specific zigzag motion trajectory design method is as follows:

[0047] S31. The rectangular slab has a rectangular outer frame with a length of 814mm and a width of 264mm. The spherical enveloping mold starts from point A and moves along the long side at a speed of 814mm / s to point B, completing motion one. Then, with an angle of 9.211° with the long side as the direction of movement, it moves at a speed of 824.633mm / s to point C, completing motion two. Next, with an angle of 9.211° with the long side as the direction of movement, it moves at a speed of 824.633mm / s to point F, completing motion three.

[0048] S32. Based on step S21, starting from point F, first move along the long side of the rectangular slab at a speed of 814 mm / s to point E to complete motion four. Then, with the angle between the slab and the long side being 9.211° as the direction of movement and the speed being 824.633 mm / s, move to point E to complete motion five. Next, with the angle between the slab and the long side being 9.211° as the direction of movement and the speed being 824.633 mm / s, motion A completes motion six. This completes one full cycle of the zigzag path movement. Figure 6 As shown;

[0049] S33. When the spherical enveloping mold moves along a broken path, the spherical enveloping mold rolls around the center of the sphere and along an axis perpendicular to the direction of the horizontal broken line movement. The rolling angular velocity on the long side is 0.0698 rad / s, and the rolling angular velocity on the inclined side is 0.0707 rad / s. The entire forming process requires 11 complete cycles, and each complete cycle is 6s.

[0050] S34. While the spherical enveloping die is moving, the die cavity moves vertically upward along the z-axis at a speed of 0.0833 mm / s.

[0051] S4. Process Design: The multi-degree-of-freedom point envelope forming device for thin-walled high-rib aircraft wing consists of a spherical envelope mold, a concave mold, a rectangular slab, a pressure plate, and a top plate.

[0052] S41. Mold and blank assembly: Place the rectangular blank 4 inside the die 2, with the lower surface of the rectangular blank 4 contacting the bottom surface of the cavity of the die 2. Install the pressure plate 3 above the die, the structure of which is as follows: Figure 7 As shown, the pressure plate 3 contacts the upper surface of the rectangular blank 4, fixing the rectangular blank 4 inside the die 2; the spherical enveloping die 1 is installed above the rectangular blank 4, with the axis of the spherical enveloping die 1 coinciding with the z-axis, and the cavity surface of the spherical enveloping die 1 contacting the upper surface of the rectangular blank 4, as shown. Figure 8 As shown;

[0053] S42. Multi-degree-of-freedom point enveloping forming: The spherical enveloping die rolls along the broken line trajectory on the upper surface of the rectangular blank, while the die moves upward along the z-axis. Under the combined action of the spherical enveloping die and the die, the metal flows in multiple directions and continuously fills the high-rib cavity of the spherical enveloping die. The rectangular blank gradually thins while the high rib gradually grows, realizing the integral forming of thin-walled high-rib aircraft wing ribs and obtaining aircraft wing rib forgings.

[0054] Figure 9 The diagram shows the forming process of an aircraft wing rib. As can be seen from the diagram, under the action of the spherical enveloping mold, the web of the preform gradually thins and the high ribs gradually grow, eventually resulting in a thin-walled, high-rib aircraft wing rib component. In summary, the high-performance, high-efficiency, multi-degree-of-freedom point enveloping forming method for thin-walled, high-rib aircraft wing ribs proposed in this invention is feasible.

[0055] This invention presents a high-performance, high-efficiency, multi-degree-of-freedom point envelope forming method for thin-walled, high-rib aircraft wing ribs. Through continuous, localized multi-degree-of-freedom loading of the mold, multi-directional coordinated metal flow is achieved, resulting in the one-time integral forming of the thin-walled, high-rib aircraft wing rib. Because the spherical envelope mold and the aircraft wing rib are in point contact, the forming force is small, allowing for active control of the metal flow. Currently, there are no reports on high-performance, high-efficiency, multi-degree-of-freedom point envelope forming methods for thin-walled, high-rib aircraft wing ribs.

[0056] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs, characterized in that, The multi-degree-of-freedom point envelope forming device includes a spherical envelope mold, a concave mold, a rectangular blank, a pressure plate, and a top block; thin-walled The method for forming high-rib aircraft wing multi-degree-of-freedom point envelopes includes the following steps: S1. Place the rectangular blank in the cavity mold, with the lower surface of the rectangular blank in contact with the bottom surface of the cavity mold. Install a pressure plate above the cavity mold, with the pressure plate in contact with the upper surface of the rectangular blank and fixing the rectangular blank in the cavity mold. Install a spherical enveloping mold above the rectangular blank, with the cavity surface of the spherical enveloping mold in contact with the upper surface of the rectangular blank. S2. First, move the spherical enveloping mold to the long side of the back of the rectangular slab. l a Above one of the apexes, the die pushes the rectangular slab upwards. s The distance causes the spherical envelope die to press into the rectangular slab; the spherical envelope die is driven along the long side. l a Move to the other vertex of the long side, and then along the same long side... l a The included angle is θ Move diagonally forward to the opposite short side, then move along the long side. l a The included angle is π- θ The direction moves diagonally forward to the other short side, and the above movement is repeated until the spherical envelope mold moves to the front long side of the rectangular slab. l b Up to the vertex; thereafter continue driving the spherical envelope mold along the long front side of the rectangular slab. l b Move to the other vertex of the long side, and then along the same long side... l b The included angle is θ Move diagonally backward to the opposite short side, then move along the long side. l b The included angle is π- θ The direction continues to move diagonally backward to the other short side, repeating the above movement until the spherical envelope mold moves to the initial position, completing one cycle of multi-degree-of-freedom point envelope motion along a polygonal trajectory; the spherical envelope mold is driven to complete multiple cycles of multi-degree-of-freedom point envelope motion along a polygonal trajectory according to the above rules, until the die pushes the rectangular blank upward to the set distance. S Under the combined action of the spherical enveloping die and the die, the rectangular slab undergoes continuous local large plastic deformation. The metal flows in multiple directions and continuously fills the high-rib cavity of the spherical enveloping die. As the rectangular slab gradually thins, the high ribs gradually grow. At different times, the cavity surface of the spherical enveloping die together envelops and forms the high-rib surface of the aircraft wing rib, ultimately achieving the one-time integral forming of the thin-walled high-rib aircraft wing rib and obtaining the aircraft wing rib forging. S3. Drive the die cavity downwards to gradually separate the forging from the spherical enveloping die; remove the pressure plate, and use the ejector blocks arranged in the die cavity to eject the forging from the die cavity, thus separating the forging from the die cavity; the spherical enveloping die is used to form the high-rib profile of aircraft wing rib forgings, and the design method of the spherical enveloping die cavity surface includes the following steps: S41. A straight line perpendicular to the upper surface of the rectangular slab and passing through the geometric center of the rectangular slab is taken as... z Axis, with z The origin is the point where the axis intersects with the upper surface of the rectangular slab. O to pass through the origin O And the straight line parallel to the length direction of the rectangular slab is x Establish coordinate system O-xyz ; S42. The high-rib surface of the thin-walled high-rib aircraft wing rib component is discretized into a point cloud. Under the coordinate system established in step S41, the coordinates of all points in the point cloud are obtained. The coordinate transformation is performed by the coordinate transformation formula (1) to form a spherical envelope model surface point cloud. （1） In the formula Let the coordinates be any point in the point cloud of the high-rib profile of a thin-walled, high-rib aircraft wing. For points The corresponding coordinates of the spherical envelope module points, where R is the radius of the spherical envelope module. ; S43 and S42: The point cloud of the spherical envelope model surface is fitted into a curved surface to obtain the spherical envelope model cavity surface for multi-degree-of-freedom point envelope forming of thin-walled, high-rib aircraft wing ribs.

2. The method for forming thin-walled, high-rib aircraft wing ribs using a multi-degree-of-freedom point envelope, as described in claim 1, is characterized in that... In step S2, during the multi-degree-of-freedom enveloping motion of the spherical enveloping mold, the spherical enveloping mold continuously rolls along a polygonal trajectory on the surface of the rectangular slab; the number of polygonal segments traversed by the spherical enveloping mold during one cycle of multi-degree-of-freedom enveloping motion along the polygonal trajectory is... n ,in n and θ The following relationship must be satisfied: In the formula, a The length of the long side of the rectangular slab; b The length of the shorter side of the rectangular slab; n It is an integer.

3. The method for forming thin-walled, high-rib aircraft wing ribs using a multi-degree-of-freedom point envelope, as described in claim 1, is characterized in that... The design methods for aircraft wing rib forgings include: The high-rib section of the thin-walled high-rib aircraft wing rib consists of five short ribs and two long ribs. Based on the dimensions of the aircraft wing rib parts, a machining allowance of 1-2 mm is added to both the high rib and the web surface of the aircraft wing rib. A draft angle of 2°-5° is added to the side of the high rib. First, longitudinal flash is designed around the web, and then transverse flash is designed at the top of the longitudinal flash, forming a stepped flash structure for the aircraft wing rib forging. The web is extended 10-15 mm in all directions to form a pressure flash, which is used to constrain the forging in the die cavity through the pressure plate to prevent the forging from warping and deforming.

4. The method for forming thin-walled, high-rib aircraft wing ribs using a multi-degree-of-freedom point envelope, as described in claim 1, is characterized in that... The outer contour of the pressure plate is consistent with the outer contour of the die, and the inner contour is consistent with the outer contour of the longitudinal flash of the forging. The pressure plate is divided into two halves along the center line of the width direction of the pressure plate to form a split pressure plate that facilitates demolding of the forging.

5. The method for forming thin-walled, high-rib aircraft wing ribs using a multi-degree-of-freedom point envelope, as described in claim 1, is characterized in that... A top block is set inside the die cavity. The top block is located below the short rib of the formed aircraft wing rib forging. The top block is rectangular in shape, with its width matching the width of the short rib of the forging, its length less than the length of the short rib of the forging, and its thickness 5~10mm thicker than the die cavity.

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