Forming Die Surface Compensation and Correction Method for Hat-Shaped Composite Parts

Abstract

The present invention discloses a method for compensating and correcting the forming die surface of a hat-shaped composite part, which belongs to the technical field of composite part manufacturing, and includes: comparing and calculating the measured data set of the actual part with the target data set of the target part to obtain the springback deformation angle; taking the die surface of the forming die as the research object, on each cross-section, taking the intersection point of the curvature extension lines of the two line segments on both sides of each fillet as the rotation point, and performing reverse rotation compensation in the springback direction according to the springback deformation angle; performing fillet processing on the included angle A between the curvature extension lines of the two line segments on both sides of the fillet after the reverse rotation compensation to obtain each compensated cross-section; using the connecting ridge lines of each fillet on the target part as the guiding lines, connecting each compensated cross-section to construct the compensated die surface, and performing compensation and correction of the die surface of the forming die based on this die surface.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material part manufacturing, and particularly relates to a method for compensating and correcting the forming die surface of a hat-shaped composite material part. Background Art

[0002] The application of composite materials in the aviation field can effectively improve the performance of modern aviation. While improving performance, it can also reduce manufacturing costs and operation and maintenance costs. Currently, composite materials have become the application materials for aerospace vehicles such as spacecraft, satellites, airplanes, rockets, and even unmanned aerial vehicles.

[0003] Aerospace vehicles have relatively high requirements for the assembly surface accuracy of main load-bearing structural parts or parts involving key assembly areas to avoid problems such as increased weight of gaskets and stress assembly during subsequent assembly processes. Hat-shaped composite material parts are generally processed by autoclave molding technology and experience the entire heating and cooling curing cycle process in the autoclave. Due to the differences in thermal expansion coefficients of different materials, the curing reaction shrinkage of the polymer matrix, and the interaction between the mold and the product, there will inevitably be a certain surface deviation between the final formed shape of the part and the theoretical model.

[0004] As Figure 1 shown, the hat-shaped composite material part includes a hat top 10, a hat waist 20, and a hat bottom 30. The connections between the hat top 10 and the hat waist 20 and between the hat waist 20 and the hat bottom 30 are all provided with rounded corners 40. The deformation of one rounded corner 40 will affect the deformation of other rounded corners 40. For long-truss parts with a large aspect ratio, there are not only angular springback deformations in the cross-section but also torsional deformations in the axial direction of the part. The actual obtained product is the comprehensive result of the deformation in the cross-section and the axial twist.

[0005] Currently, the die surface compensation is mainly carried out by the method of springback angle compensation. Specifically, the rotation base point for deformation compensation is the tangent point of the rounded corner for rotation, and the rotated graph is smoothly transitioned and approximately replaced by the compensated graph. This processing method does not conform to the actual deformation behavior of the rounded corner and has a large deviation when controlling the surface with high precision. Moreover, this method has certain limitations. When compensating for the deformation of parts with complex cross-sectional shapes, especially those with arcs in the cross-sectional shape or torsions and warps in the overall axial direction of the part, it is difficult to obtain a high surface control accuracy. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for compensating and correcting the forming die surface of a hat-shaped composite material part, which reduces the compensation deviation of the springback deformation of the rounded corners of the hat-shaped part, completes the compensation for the axial torsional deformation of the part, and improves the precision control of the part surface.

[0007] Based on the above concept, the technical solution adopted by the present invention is as follows:

[0008] A method for compensating and correcting the forming die surface of a hat-shaped composite part, comprising:

[0009] Step 1: Compare and calculate the measured data set of the actual part with the target data set of the target part to obtain the springback deformation angle, including:

[0010] Step 11: Along the length direction of the die-contact surface of the target part, select several cross-sections. Each cross-section consists of five line segments and four fillets. The adjacent two line segments are connected by fillets. Uniformly select several measurement points on each line segment within each cross-section to form the target data set. Measure the surface of the actual part according to each measurement point in the target data set to obtain the measured data set;

[0011] Step 12: Connect the two measurement points farthest from each other on each line segment on both sides of the fillet. The included angle between the extension lines of the adjacent two connections is defined as the nominal angle of the fillet. In this way, obtain the actual nominal angles of the fillets on each cross-section of the actual part and the target nominal angles of the corresponding fillets on each cross-section of the target part;

[0012] Step 13: On each cross-section, at each fillet, use the angle difference between the actual nominal angle and the target nominal angle as the springback deformation angle of the fillet on this cross-section;

[0013] Step 2: Take the die surface of the forming die as the research object. On each cross-section, take the intersection point of the curvature extension lines of the two line segments on both sides of each fillet as the rotation point, and perform reverse rotation compensation in the springback direction according to the springback deformation angle;

[0014] Step 3: Perform filleting on the included angle A between the curvature extension lines of the two line segments on both sides of the fillet after reverse rotation compensation to obtain each compensated cross-section;

[0015] Step 4: Take the connecting ridge lines of the fillets on the target part as the guiding lines, connect each compensated cross-section, construct the compensated die surface, and perform the compensation and correction of the die surface of the forming die based on this die surface;

[0016] Step 5: Use the compensated forming die to manufacture the secondary actual part, measure the die surface of the secondary actual part, and compare it with the target part. If the die surface deviation does not meet the requirements, repeat Steps 1 - 4 to continue the compensation and correction of the die surface until the die surface deviation meets the requirements.

[0017] Wherein, in Step 12, in a single cross-section, on each line segment on both sides of the fillet, connect the two measurement points farthest from each other to respectively obtain two straight lines located on both sides of the fillet. Intersect the extension lines of the two straight lines, and use the formed angle as the nominal angle.

[0018] Among them, for the rounded corner at the junction of the cap bottom and the cap waist, in the cap bottom area, the first straight line is obtained by connecting the measurement points, and in the cap waist area, the second straight line is obtained by connecting the measurement points. The extension line of the first straight line intersects with the extension line of the second straight line, and the formed nominal angle is used as the female nominal angle;

[0019] For the rounded corner at the junction of the cap top and the cap waist, in the cap top area, the third straight line is obtained by connecting the measurement points. The extension line of the second straight line intersects with the extension line of the third straight line, and the formed nominal angle is used as the male nominal angle.

[0020] Among them, in step 3, the rounded corner processing is carried out, including:

[0021] According to the arc length formula, on the premise that the arc length remains unchanged before and after deformation compensation, the rounded corner processing is carried out for each included angle A in each cross-section to obtain a new rounded corner.

[0022] Among them, the arc length formula is L = nπr / 180, where the central angle of the rounded corner on the target part is n and the central radius is r. Assuming that the central angle of the new rounded corner is n' and the central radius is r', according to n×r = n'×r', the central radius r' of the new rounded corner is calculated, and r' is used to carry out the rounded corner processing for the included angle A.

[0023] Among them, before step 1, it also includes:

[0024] Step 01: Based on the mold-attached surface of the target part, in the part coordinate system, a tooling data set is created. Based on the tooling data set, a forming mold is manufactured, and the actual part is manufactured using the forming mold.

[0025] Among them, in step 11, the distance between adjacent cross-sections is 5 - 20 cm, each cross-section is parallel to each other, and 3 - 5 measurement points are evenly selected on each line segment in each cross-section.

[0026] The beneficial effects of the present invention:

[0027] The method for compensating and correcting the forming die surface of the hat-shaped composite part proposed by the present invention selects several cross-sections along the length direction of the die-attached surface of the target part. Each cross-section consists of five line segments and four rounded corners, and adjacent two line segments are connected by rounded corners. A number of measurement points are evenly selected on each line segment within each cross-section to form a target data set. The surface of the actual part is measured according to each measurement point in the target data set to obtain an actual measurement data set; the two measurement points farthest from each other on each line segment on both sides of the rounded corner are connected, and the angle between the extension lines of adjacent two connection lines is defined as the nominal angle of the rounded corner, so as to obtain the actual nominal angles of each rounded corner on each cross-section of the actual part and the target nominal angles of each rounded corner on the corresponding cross-sections of the target part; on each cross-section, at each rounded corner, the angle difference between the actual nominal angle and the target nominal angle is used as the springback deformation angle of the rounded corner on this cross-section. For complex structure parts, especially when there are arcs in the cross-sectional shape elements, the nominal angle definition is used to complete the quantitative characterization of the characteristic angle, and the comparison between the target position and the actual deformation position is completed through the nominal angle, so as to complete the deformation compensation of the springback surface; when performing reverse rotation compensation, the intersection point of the curvature extension lines of the two line segments on both sides of the rounded corner is used as the rotation point, and reverse rotation compensation is performed in the springback direction according to the springback deformation angle; through the deformation compensation within several single cross-sections, the surface compensation of the forming die is completed, and the high-precision control of the final surface of the actual product is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of an existing hat-shaped composite part;

[0029] Figure 2 is a schematic structural diagram of the measurement points selected on the target part provided by the embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of a single cross-section of the actual part provided by the embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of the measurement points on a single cross-section of the actual part provided by the embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of the nominal angle and the rotation point of the actual part provided by the embodiment of the present invention;

[0033] Figure 6 is Figure 5 partial schematic Figure 1 ;

[0034] Figure 7 is Figure 5 partial schematic Figure 2 ;

[0035] Figure 8 isFigure 7 Enlarged view at position B;

[0036] Figure 9 It is a schematic diagram before and after the surface compensation of the forming die provided by the embodiment of the present invention.

[0037] In the figure:

[0038] 10, cap top; 20, cap waist; 30, cap bottom; 40, rounded corner; 50, female nominal corner; 60, rotation point. Specific embodiments

[0039] The following details the embodiments of the present invention. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation of the present invention.

[0040] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] Refer to Figures 2 to 9 , this embodiment provides a method for compensating and correcting the surface of a forming die for a cap-shaped composite part. By using the actual part produced by the forming die and taking the target part as a reference, the surface of the forming die is compensated and corrected so that the actual part produced by the forming die has a smaller deviation from the target part. Among them, the target part is a cap-shaped structural part.

[0042] The method for compensating and correcting the surface of a forming die for a cap-shaped composite part includes:

[0043] Step 1: Compare and calculate the measured data set of the actual part with the target data set of the target part to obtain the springback deformation angle, including:

[0044] Step 11: Along the length direction of the die-contact surface of the target part, select several cross-sections. Each cross-section is composed of five line segments and four rounded corners 40. The adjacent two line segments are connected by the rounded corner 40. Select several measurement points evenly on each line segment in each cross-section to form a target data set. Measure the surface of the actual part according to each measurement point in the target data set to obtain the measured data set;

[0045] Step 12: Connect the two measurement points farthest from each other on each line segment on both sides of the rounded corner 40. The included angle between the extension lines of the adjacent two connections is defined as the nominal angle of the rounded corner 40. In this way, obtain the actual nominal angles of the rounded corners 40 on each cross-section of the actual part and the target nominal angles of the corresponding rounded corners 40 on each cross-section of the target part;

[0046] Step 13: On each cross-section, at each fillet 40, use the angular difference between the actual nominal angle and the target nominal angle as the springback deformation angle of the fillet 40 on this cross-section.

[0047] Step 2: Take the surface of the forming die as the research object. On each cross-section, take the intersection point of the curvature extension lines of the two line segments on both sides of each fillet 40 as the rotation point 60, and perform reverse rotation compensation in the springback direction according to the springback deformation angle.

[0048] Step 3: Perform filleting on the included angle A between the curvature extension lines of the two line segments on both sides of the fillet 40 after reverse rotation compensation to obtain each compensated cross-section.

[0049] Step 4: Take the connecting ridge lines of each fillet 40 on the target part as the guiding lines, connect each compensated cross-section, construct the compensated surface, and perform surface compensation and correction of the forming die based on this surface.

[0050] Step 5: Use the compensated forming die for manufacturing to obtain the secondary actual part. Measure the surface of the secondary actual part and compare it with the target part. If the surface deviation does not meet the requirements, repeat Steps 1 - 4 to continue surface compensation and correction until the surface deviation meets the requirements.

[0051] In Step 1, both the target data set and the measured data set are based on the part coordinate system, using a unified coordinate system to facilitate one-to-one correspondence of the corresponding data. The target data set is the data obtained based on the target part, and the target part is a hat-shaped structure part, whose inner surface is the die-contact surface. The measured data set is the data obtained by measuring the surface on the actual part based on the target data set. It can be understood that the actual part is also a hat-shaped structure part, and its inner surface is the surface.

[0052] Specifically, the target data set of the target part can be obtained through measurement software, and the measured data set of the actual part can be obtained by using a coordinate measuring machine to measure the actual part according to the target data set.

[0053] When obtaining the target data set, as in Step 11, along the length direction of the die-contact surface of the target part, select several cross-sections. Each cross-section consists of five line segments and four fillets 40, and the adjacent two line segments are connected by the fillet 40. Uniformly select several measurement points on each line segment within each cross-section to form the target data set. Generally, the hat-shaped structure part includes a hat top 10, a hat waist 20, and a hat bottom 30. The fillet 40 at the junction of the hat top 10 and the hat waist 20 is a male fillet, and the fillet 40 at the junction of the hat bottom 30 and the hat waist 20 is a female fillet.

[0054] In this embodiment, the distance between adjacent cross-sections is 5 to 20 cm, and each cross-section is parallel to each other. On each line segment within each cross-section, 3 to 5 measurement points are evenly selected. By analogy, all the measurement points on the mold-attached surface are determined along the length direction of the target part. Optionally, 1 measurement point can be selected at each fillet 40 position.

[0055] It can be understood that the cross-sections on the target part correspond one-to-one with the cross-sections of the actual part, which is convenient for data comparison. Therefore, in the measured data set, there are the same number of cross-sections and the same number of measurement points as in the target data set.

[0056] In step 12, in a single cross-section, on each line segment on both sides of the fillet 40, the two measurement points with the farthest distance are connected to obtain two straight lines located on both sides of the fillet 40 respectively. The extension lines of the two straight lines intersect, and the formed angle is used as the nominal angle.

[0057] In this embodiment, for the fillet 40 at the junction of the cap bottom 30 and the cap waist 20, a first straight line is obtained by connecting the measurement points in the cap bottom area, and a second straight line is obtained by connecting the measurement points in the cap waist area. The extension line of the first straight line intersects with the extension line of the second straight line, and the formed nominal angle is used as the female nominal angle 50; for the fillet 40 at the junction of the cap top 10 and the cap waist 20, a third straight line is obtained by connecting the measurement points in the cap top area. The extension line of the second straight line intersects with the extension line of the third straight line, and the formed nominal angle is used as the male nominal angle.

[0058] It can be understood that in the cap-shaped structural part, some cap bottom areas are arc surfaces, some cap bottom areas are flat surfaces, some cap waist areas are arc surfaces, and some cap waist areas are flat surfaces. However, the junctions between the cap bottom area and the cap waist area are all arc curves, that is, fillets 40. In a single cross-section, if there is one or two arcs on the line segments on both sides of the fillet 40, for the arcs, there is no intersecting angle between the two arcs or between the arc and the straight line, so the nominal angle is defined. The quantitative characterization of the feature angle is completed by using the nominal angle, and the comparison between the theoretical position and the actual deformation position is completed through the nominal angle, so as to complete the deformation compensation of the springback surface.

[0059] For example, in a single cross-section, if the two line segments on both sides of the fillet 40 are both arcs, then the two measurement points with the farthest distance on the arcs are connected to form a straight line, and the angle formed by extending and intersecting the two straight lines on both sides of the fillet 40 is the nominal angle. In Figure 5 , the cap bottom area is an arc surface, the cap waist area is a flat surface, and the two line segments on both sides of the fillet 40 at the junction of the cap bottom 30 and the cap waist 20 are an arc and a straight line respectively. On the straight line, the connection of the two measurement points with the farthest distance is still the straight line itself. On the arc, the connection of the two measurement points with the farthest distance is a straight line, and the female nominal angle 50 is the included angle between the two straight lines, as shown in Figure 6 shown.

[0060] According to the method in Step 1, the springback deformation angles of each fillet 40 in each cross-section can be obtained.

[0061] Before Step 1, it further includes:

[0062] Step 01: Based on the die-contacting surface of the target part, create a tooling dataset in the part coordinate system. Manufacture a forming die based on the tooling dataset, and obtain the actual part by using the forming die for manufacturing.

[0063] In this embodiment, for all the data of the die-contacting surface of the target part, the surface of the actual part, and the surface of the forming die, it is necessary to ensure that they are in the same coordinate system so that the corresponding data can be in one-to-one correspondence. Therefore, the forming die surface has the same number of cross-sections and the same number of measurement points as the target dataset.

[0064] In Step 01, when manufacturing the forming die, a deformation compensation with a preset angle is given to the fillet 40 in advance on the surface of the forming die; in Step 2, reverse rotation compensation is performed according to the springback deformation angle.

[0065] For example, if the nominal angle of the fillet on the target part is 100°, and the nominal angle of the fillet on the actual part is 98°, according to experience, a deformation compensation with a preset angle of 3° can be preset on the surface of the forming die, that is, the nominal angle of the fillet on the surface of the forming die is set to 103°. Assuming that the nominal angle of the fillet of the actual part produced by the forming die at this time is 101.2°, when performing reverse rotation compensation, the springback deformation angle is 1.2°, then after reverse rotation compensation, the nominal angle of the surface is adjusted to 103° - 101.2° = 101.8°. Use the forming die with the nominal angle of the fillet on its surface being 101.8° to produce the actual part again.

[0066] In Step 2, in the part coordinate system, select the surface of the forming die as the research object. On each cross-section, take the intersection point of the curvature extension lines of the two line segments on both sides of each fillet 40 as the rotation point 60, and perform reverse rotation compensation in the springback direction according to the springback deformation angle.

[0067] For example, on a single cross-section, if the two line segments on both sides of the fillet 40 are both arcs, then extend the arcs according to the curvature of the arcs so that the two arcs intersect, and the intersection point is the rotation point 60. On a single cross-section, if the two line segments on both sides of the fillet 40 are an arc and a straight line respectively, the rotation point 60 is the intersection point of the extension line of the straight line and the curvature extension line of the arc, as Figure 8 shown. In Figures 5 to 8 the dotted line represents the connection line of the measurement points.

[0068] It should be noted that the vertex of the nominal angle and the rotation point 60 may or may not be the same point. In this embodiment, the rotation point 60 is not the tangent point of the rounded corner 40, which fully considers the actual deformation behavior of the rounded corner 40. When compensating for the deformation of parts with complex cross-sectional shapes, especially those with arcs in the cross-sectional shape or torsion and warping in the overall axial direction of the workpiece, higher surface control accuracy can be obtained.

[0069] Based on the method for obtaining the rotation point 60 in step 2 and combined with the springback deformation angle obtained in step 1, reverse rotation compensation is performed on each rounded corner 40 in each cross-section.

[0070] It can be understood that the reverse rotation compensation will cause the current rounded corner 40 not to match the two line segments after compensation. After the reverse rotation compensation, the included angle A between the curvature extension lines of the two line segments on both sides of the rounded corner 40 needs to be chamfered again.

[0071] Among them, the rounded corner is replaced by an arc that is tangent to both sides of the angle. In actual production, chamfering is a machining technique, which refers to the machining of cutting the edges of the workpiece into an arc surface and is a commonly used machining method.

[0072] The "chamfering" mentioned in this embodiment refers to processing the included angle A on each cross-section into a rounded corner on the digital model of the part.

[0073] In step 3, chamfering is performed, including:

[0074] According to the arc length formula, based on the premise that the arc length remains unchanged before and after deformation compensation, chamfering is performed on each included angle A in each cross-section to obtain a new rounded corner. Figure 9 Part of the schematic diagrams of the cross-sections before and after compensation deformation are shown, and the included angle A between the curvature extension lines of the two line segments on both sides of the rounded corner after compensation deformation is as Figure 9 identified in.

[0075] Specifically, the arc length formula is L = nπr / 180, where the central angle of the rounded corner on the target part is n and the central radius is r. Assuming that the central angle of the new rounded corner is n' and the central radius is r', n×r = n'×r'. Calculate the central radius r' of the new rounded corner, and use r' to perform chamfering on the included angle A. The calculation method of the central angle of the new rounded corner is as follows: After the reverse rotation compensation, the sum of the included angle between the tangents of the endpoints of the two line segments on both sides of the rounded corner 40 and the central angle of the new rounded corner is 180°, and then the central angle of the new rounded corner is calculated. Based on the premise that the arc length remains unchanged before and after deformation compensation, the chamfering is more accurate, and the newly chamfered rounded corner can smoothly connect the two side line segments. Based on the above step 3, chamfering is performed on each included angle A on each cross-section.

[0076] In step 4, the connecting ridge lines of the fillets on the target part are used as guide lines to connect the compensated sections to construct the compensated surface. This is a software operation method and is an existing operation method, which will not be repeated here.

[0077] Taking the door wall panel of a certain aircraft as an example, its structure is a large-size hat-shaped long stringer reinforced wall panel structure, which is manufactured using an autoclave co-bonding process. After the hat-shaped long stringer is cured and formed, it is bonded to the uncured skin as a whole. The molding mold surface compensation and correction method for the hat-shaped composite material part provided in this embodiment is used to compensate and correct the molding mold surface.

[0078] In general, the hat-shaped structural parts include a hat top, a hat waist and a hat bottom. The fillet at the junction of the hat top and the hat waist is a positive fillet, and the fillet at the junction of the hat bottom and the hat waist is a negative fillet. It can be understood that the hat-shaped long girder structure forms a "geometric interlocking" structure on the cross section, and the rebound deformation behaviors of the negative fillet area and the positive fillet area will affect each other. The final deformation behavior on the cross section is the coupling result of the deformation of the two areas. In addition, the length of the hat-shaped long girder structure is relatively large, far exceeding the length of conventional hat-shaped long girder structural parts. In this embodiment, the hat-shaped long girder structure is a hyperbolic free-form surface, and the projection in the length direction is 1442mm, and the projection in the width direction is 254mm.

[0079] On the digital model of the target part, a section is taken at intervals of 100 mm, and a total of 16 sections are taken. It can be understood that the interval between the last section and the adjacent section is less than 100 mm. In actual operation, the number and interval of sections can be selected as needed, and there is no limitation here. Four measurement points are evenly taken on each line segment of each section. The points on the remaining sections can be arrayed using the points on the first section, and automatic measurement is run to obtain a point cloud set as the target data set to obtain the spatial coordinates of the measurement points.

[0080] Taking the mold surface of the target part as the reference, in the part coordinate system, create a tooling data set according to the engineering modeling method, perform structural modeling based on the tooling data set, manufacture the physical molding mold, use the molding mold to manufacture the actual part, and complete the manufacturing of the first actual part according to the process control requirements.

[0081] Among them, based on previous engineering experience, the deformation direction of the part can be determined in advance. During the design of the initial molding mold, all female fillets are given a deformation angle pre-compensation of +2.7° (between 1 and 3°), and all male fillets are given a deformation angle pre-compensation of +1.7° (between 1 and 2°).

[0082] After obtaining the actual part for the first time, the surface of the actual part is measured according to each measurement point position in the target data set to obtain the measured data set; in the measured data set, there are also 16 cross-sections, and 4 measurement point positions are evenly taken on each line segment of each cross-section, so that the measured data set corresponds one by one with the target data set.

[0083] According to Step 12, the nominal angle obtained by extending the line connecting the measurement point positions on both sides of the fillet at the junction of the cap bottom and the cap waist is the female nominal angle, which is about 92°. The nominal angle obtained by extending the line connecting the measurement point positions on both sides of the fillet at the junction of the cap top and the cap waist is the male nominal angle, which is about 100°. Among them, the vertical distance from the cap top to the cap bottom is 100 mm. The influence of the angle deviation in the fillet area on the surface deviation is that when the male fillet has an angle deviation of 0.1°, the maximum surface deviation of 0.2 mm will be generated in the bottom area of the cap waist.

[0084] On the target part, the angles of the target nominal angles of each fillet on each cross-section are obtained respectively, which are divided into the target values of the female nominal angle and the male nominal angle. On the actual part, the angles of the actual nominal angles of each fillet on each cross-section are obtained respectively, which are divided into the actual values of the female nominal angle and the male nominal angle. Since there are two female nominal angles and two male nominal angles on each cross-section, the measurement results are as follows:

[0085]

[0086] Based on the angle differences between the actual nominal angles and the target nominal angles of each fillet in each cross-section obtained by comparison and calculation, the springback deformation angle is obtained, and the angles of each fillet in each cross-section are adjusted. Specifically, on each cross-section, the intersection point of the curvature extension lines of the two line segments on both sides of each fillet is used as the rotation point, and reverse rotation compensation is performed according to the springback deformation angle.

[0087] According to the data in the table, taking the male nominal angle 2 of the first cross-section as an example, the target value of the male nominal angle 2 is 100°, the actual value of the male nominal angle 2 is 100.439°, and the male nominal angle 2 has a positive deviation of 100.439° - 100° = +0.439°. Therefore, the springback deformation angle is +0.439°. Because a preset angle of +1.7° is given in the design process of the initial forming die, the +1.7° pre-compensation of the male fillet 2 is adjusted reversely to +1.261° according to the calculation results of the springback deformation angle and the preset angle, so that the male fillet 2 of the surface is 101.261°. Among them, 1.261° = 1.7° - 0.439°.

[0088] Perform a fillet operation on the included angle A between the curvature extension lines of the two line segments on both sides of the fillet after reverse rotation compensation. Taking the male nominal angle 2 of the first section as an example, the central angle of the fillet on the target part is 80°, and the central radius is r = 5 mm. Assuming the central angle of the new fillet is 78.74°, calculate the new fillet radius r' = 5.08 mm, and perform a fillet operation using the new chamfer radius.

[0089] Among them, the calculation method for the central angle of the new fillet being 78.74° is as follows: As described above, reverse adjust the pre-compensated +1.7° of the male fillet 2 to +1.261°, so that the actual value of the compensated male nominal angle 2 is 101.26°. Since the two line segments on both sides of the fillet are straight lines, the included angle between the tangents at the endpoints of the two line segments is equal to the actual value of the male nominal angle 2. According to the fact that the sum of the included angle between the tangents at the endpoints of the two line segments on both sides of the fillet and the central angle of the new fillet is 180°, the central angle of the new fillet is 78.74°.

[0090] According to this method, specifically complete the reverse compensation work for all fillets in all cross-sections.

[0091] For all cross-section graphics after compensation, using the connecting ridge line of the fillet as the guiding line, connect the compensated cross-sections to construct the compensated surface, and based on this surface, perform surface compensation and correction on the forming die.

[0092] Use the compensated forming die to manufacture the secondary actual part, measure the surface of the secondary actual part, and compare it with the target part. If the surface deviation does not meet the requirements, repeat the surface compensation and correction until the surface deviation meets the requirements.

[0093] After using the method of this embodiment to correct the surface of the forming die, the surface deviation range of the product can be reduced from ±1.3 mm to below ±0.3 mm.

[0094] In traditional fillet springback deformation compensation, usually use the tangent point of the fillet as the rotation point for deformation compensation rotation, and smoothly transition the rotated graph, approximately substituting it as the compensated graph. This processing method uses a unified springback angle for all angle deformation compensations, which does not conform to the actual deformation behavior of the fillet area. Firstly, reliable cross-section springback adjustment data cannot be obtained, and secondly, effective compensation for axial torsional deformation cannot be carried out, resulting in a large deviation when there is high-precision surface control.

[0095] For the traditional springback deformation compensation method of the fillet area and the forming die surface compensation and correction method of the hat-shaped composite part in this embodiment, the maximum alignment deviation of the cross-sectional curves obtained by the two processing methods can reach about 1.5 mm. Therefore, in this embodiment, on the cross-section, for the case where the cross-sectional shape is an arc, the nominal angle is used to calculate all the characteristic angle deformations, and the intersection point of the curvature extension lines of the line segments on both sides of the fillet is used as the rotation point for cross-sectional deformation compensation. In the length direction, multiple cross-sections are used for separate compensation and the overall surface simulation method can enable the final formed product to obtain a more efficient die surface control result.

[0096] The above embodiments only illustrate the basic principles and characteristics of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, there are various changes and modifications to the present invention, and these changes and modifications all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. Forming die surface compensation and correction method for hat-shaped composite material parts, characterized in that Including: Step 1: Compare and calculate the measured data set of the actual part with the target data set of the target part to obtain the springback deformation angle, including: Step 11: Along the length direction of the mold-contact surface of the target part, select several cross-sections. Each cross-section consists of five line segments and four fillets. The adjacent two line segments are connected by fillets. Uniformly select several measurement points on each line segment within each cross-section to form the target data set. Measure the surface of the actual part according to each measurement point in the target data set to obtain the measured data set; Step 12: Connect the two measurement points farthest from each other on each line segment on both sides of the fillet. The included angle between the extension lines of the adjacent two connections is defined as the nominal angle of the fillet, so as to obtain the actual nominal angles of the fillets on each cross-section of the actual part and the target nominal angles of the corresponding fillets on each cross-section of the target part; Step 13: On each cross-section, take the angle difference between the actual nominal angle and the target nominal angle at each fillet as the springback deformation angle of the fillet on this cross-section; Step 2: Take the surface of the forming mold as the research object. On each cross-section, take the intersection point of the curvature extension lines of the two line segments on both sides of each fillet as the rotation point, and perform reverse rotation compensation in the springback direction according to the springback deformation angle; Step 3: Perform filleting on the included angle A between the curvature extension lines of the two line segments on both sides of the fillet after reverse rotation compensation to obtain each compensated cross-section; Step 4: Take the connecting ridge lines of the fillets on the target part as the guiding lines, connect each compensated cross-section, construct the compensated surface, and perform surface compensation and correction on the forming mold based on this surface; Step 5: Use the compensated forming mold to manufacture the secondary actual part, measure the surface of the secondary actual part, and compare it with the target part. If the surface deviation does not meet the requirements, repeat Steps 1 - 4 to continue the surface compensation and correction until the surface deviation meets the requirements.

2. The method for compensating and correcting the forming die surface of the hat-shaped composite material part according to claim 1, wherein, In Step 12, in a single cross-section, on each line segment on both sides of the fillet, connect the two measurement points farthest from each other to respectively obtain two straight lines located on both sides of the fillet. Extend the two straight lines until they intersect, and the formed angle is used as the nominal angle.

3. The method for compensating and correcting the forming die surface of the hat-shaped composite material part according to claim 2, characterized in that, For the fillet at the junction of the cap bottom and the cap waist, obtain the first straight line by connecting the measurement points in the cap bottom area, obtain the second straight line by connecting the measurement points in the cap waist area, extend the first straight line and intersect it with the extension line of the second straight line, and the formed nominal angle is used as the female nominal angle; For the fillet at the junction of the cap top and the cap waist, obtain the third straight line by connecting the measurement points in the cap top area, extend the second straight line and intersect it with the extension line of the third straight line, and the formed nominal angle is used as the male nominal angle.

4. The method for compensating and correcting the forming die surface of the hat-shaped composite material part according to claim 1, characterized in that, In Step 3, the filleting process includes: According to the arc length formula, based on the premise that the arc length remains unchanged before and after deformation compensation, perform filleting on each included angle A within each cross-section to obtain a new fillet.

5. The method for compensating and correcting the forming die surface of the hat-shaped composite part according to claim 4, characterized in that The arc length formula is L = nπr / 180. The central angle of the fillet on the target part is n and the central radius is r. Assuming that the central angle of the new fillet is n' and the central radius is r', according to n×r = n'×r', the central radius r' of the new fillet is calculated, and r' is used to perform a chamfering process on the included angle A.

6. The method for compensating and correcting the forming die surface of the hat-shaped composite material part according to claim 1, characterized in that, Before step 1, it also includes: Step 01: Based on the die-contact surface of the target part, in the part coordinate system, create a tooling data set. A forming die is manufactured based on the tooling data set, and an actual part is obtained by manufacturing with the forming die.

7. The method for compensating and correcting the forming die surface of the hat-shaped composite part according to claim 1, wherein In step 11, the spacing between adjacent cross-sections is 5 - 20 cm, and each cross-section is parallel to each other. 3 - 5 measurement points are evenly selected on each line segment within each cross-section.

Images