A method for manufacturing a precision compatible mold for an aluminum alloy automobile fender

Abstract

The present invention discloses a method for manufacturing a precision compatible mold for an aluminum alloy automobile fender, which solves the technical problem that the prior art cannot achieve mold forming of automobile cover parts of aluminum alloy deep cavity fenders while meeting high surface quality accuracy, and at the same time meet the technical problem of common mold interchangeable manufacturing of aluminum alloy plates and traditional materials. The technical solution provided by the present invention includes the following steps: compatible material surface forming calculation, floating forming and partition forming, step-by-step arrangement of drawbeads, surface control reverse drawing extension, high-fit processing, rolling oil protection debugging and corner cutting debugging, and secondary fine-tuning determination. The technical solution provided by the present invention not only solves the problem that aluminum alloy deep cavity fenders cannot be formed by cold stamping molds due to their surface quality problems and material property problems, but also creates a classic technical model for the forming of parts of similar shapes, which can be promoted and applied in a variety of forming processes.

Description

Technical Field

[0001] The invention relates to the technical field of cold stamping dies for automobile fenders, and in particular to a method for manufacturing a precision compatible die for aluminum alloy automobile fenders. Background Art

[0002] Among automobile covering parts (referred to as parts), outer panels are responsible for the quality of covering parts and have strict quality requirements. Due to the small number of shape control points, molding control is extremely difficult. Fenders are the most difficult typical outer panel parts. They have many overlapping parts, large molding depth, high overall streamline requirements, and weak shape continuity, making them typical difficult parts of automobile covering parts molds (referred to as molds).

[0003] With the increasing demand for lightweight vehicles, aluminum alloy has become the first choice for lightweighting due to its high degree of lightweighting, low price, excellent performance and strong corrosion resistance. However, as fenders are typical difficult covering parts, they have many overlaps on the body, the overall covering parts have high requirements for appearance, are characterized by deep cavities and have few molding control lines, and it is already very difficult to mold them using traditional materials.

[0004] However, aluminum alloy sheets have many surface defects such as large rebound, poor ductility, easy cracking, and roughening, which makes forming more difficult. Only simple shapes can be debugged in a complicated way that relies on the craftsman's skills. The development and production of automobile cover molds that are compatible with aluminum alloy sheets and other sheets is currently impossible. Although new technologies for ordinary automobile covers can achieve multi-material co-mold manufacturing through technical solutions such as drawbead control, fenders, as the quality of the surface, require high surface quality. The drawbead control mode cannot meet the surface quality requirements, so co-mold manufacturing cannot be implemented.

[0005] Therefore, developing a new technical solution to achieve the mold forming of automobile cover parts of aluminum alloy deep cavity fenders while meeting high surface quality accuracy, and at the same time meeting the common mold interchangeable manufacturing of aluminum alloy sheets and traditional materials is a key problem in the industry. Its main technical difficulties are reflected in the following aspects:

[0006] 1. Material viscosity problem of aluminum alloy and the resulting surface problems such as slip line and roughness;

[0007] 2. The springback and uncertainty issues of deep cavity fenders;

[0008] 3. The problem of being unable to use drawbeads to control forming due to high surface quality requirements;

[0009] 4. Compatible with the key feature distortion problem caused by material property differences when molding other materials.

[0010] It should be particularly noted that the above technical information is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as admitting or implying in any form that the above technical information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0011] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a method for manufacturing a precision compatible mold for an aluminum alloy automobile fender, which solves the technical problem that the prior art is unable to achieve mold forming of automobile covering parts of an aluminum alloy deep-cavity fender while meeting the requirements of high surface quality accuracy, and at the same time meet the requirements of common mold interchangeable manufacturing of aluminum alloy sheets and traditional materials.

[0012] The technical solution of this application is:

[0013] A method for manufacturing a precision compatible mold for an aluminum alloy automobile fender comprises the following steps:

[0014] Step 1: Compatible material surface forming calculation: Use CAE analysis to provide suitable process modeling for high-precision surface forming, distinguish the forming differences of different materials, select the forming difficult areas and differentiated areas, and provide basic support for subsequent processes;

[0015] Step 2: Floating molding and partition molding; Floating molding and partition molding mainly solve the molding problems of deep cavity top and difficult-to-form area left over from the first-order process number, and optimize the overall molding force of the fender shape, while protecting the molding of key areas to form a total force change trend, reduce molding defects and the generation of burrs and slip lines;

[0016] Step 3: Arrange the drawbeads in stages;

[0017] Step 4: Surface control reverse drawing and extension: reverse drawing and extension are performed on the overlapped side of the part and the wheel cover, and the overall S-shaped trend is formed in coordination with the partition molding to reduce molding defects. At the same time, the rebound trend after cutting is inward, forming a trend that is conducive to overall molding and eliminating the uncertainty of secondary molding.

[0018] Step 5: High-fitting processing: Improve the partition molding and surface molding control through the processing mode, provide adjustment amount for the later debugging of craftsman skills, avoid repeated adjustment and repeated processing, and consist of two parts: program preprocessing and super finishing;

[0019] Step 6: Calendering oil protection debugging and corner cutting debugging;

[0020] Step 7: Secondary finishing is confirmed; during trimming and forming, for the overlapping edges of complex-shaped edges and corners with complex shape changes, the method of rough trimming first, then flanging and shaping, and then secondary finishing and punching is adopted.

[0021] Step 8: Finished Product.

[0022] Preferably, the main operation mode of step 1 is as follows:

[0023] Step 1.1: Perform a general forming analysis on the fender, and then select the high curvature area that cannot be formed for digital model optimization to reduce the high curvature risk points;

[0024] Step 1.2: Construct a process digital model according to the aluminum alloy material. During the construction process, weak drawbead control is adopted, that is, the drawbead is as short as possible and appropriately widened, and the drawbead is arranged in a single-bead mode. The position of the drawbead should be close to the part contour, and the position close to the part contour and where the drawbead can be smoothly placed is repeatedly calculated to place the drawbead; then optimize the process adjustment, repeatedly calculate and continuously adjust, so that the difficult forming area is concentrated on the top of the deep cavity and some difficult-to-form areas, thereby obtaining the first-order process type;

[0025] Step 1.3: Take the first-order process type as the basic process type for calculation, set the parameters to the parameters of the common sheet material that needs to be compatible, and then expand the blank line. The expansion method is to first expand the overlap area between the part and the bonnet and the overlap area with the side panel. The initial expansion amount is 30mm, and then construct the second-order draw ribs from the outside to the inside of the expanded area by 15mm. Calculate whether the common sheet material can be fully formed; if it can be formed, this process type is a second-order process type; if it cannot be fully formed, extend the blank line to the headlight area and part of the wheel overlap area until the common sheet material can be fully formed. At this time, the process type is a second-order drawing process type.

[0026] Preferably, when performing the step 1.2, it is necessary to pay attention to weakening or eliminating some draw ribs as much as possible in the wheel overlap area where the fender undulation is smaller; when performing the step 1.3, it is necessary to pay attention that the wheel overlap area cannot be completely provided with second-order draw ribs, and at least 75 mm or more of the draw rib-free area is left to form a reverse drawing fracture.

[0027] Preferably, the steps of step 2 are as follows:

[0028] Step 2.1: For the top difficult-to-form area, set rectangular or circular inserts according to the atmosphere that can cover 60%-80% of the area inside, establish floating forming blocks, and pay attention to the edge lines of the floating blocks to divide them along the concave area or corner lines of the parts as much as possible;

[0029] Step 2.2: For other difficult-to-form convex areas, a floating forming block is established by local segmentation, which is not limited by the coverage range, but must comply with the requirements of segmentation along the concave area or the corner line. At the same time, the number of segments should be as small as possible, and the minimum diameter or side length of the segment should not be less than 50mm, otherwise the floating forming block cannot be formed;

[0030] Step 2.3: Add a bottom pressure source to the floating forming block, do pre-forming in advance, the floating height is generally within 50mm of the overall height, and use CAE to analyze and calculate the height and corresponding pressure that can achieve full forming;

[0031] Step 2.4: When the material is changed to compatible ordinary material molding, remove the pressure source and cancel floating molding;

[0032] Step 2.5: Zoning molding: Zoning molding is a method of combining strong pressure with weak pressure, and prioritizing the overall noodle quality and local complex features to ensure the noodle quality and feature accuracy of the overall product;

[0033] Step 2.6: The process type after floating molding and partition molding arrangement is a three-stage process type.

[0034] Preferably, the zone forming described in step 2.5 is from the overall shape, starting from the overlapping edge of the overlapping hair cover, upward to the highest area of ​​the product, which is the first strong pressure forming area, and the area is subject to key strong pressure forming, and the gap is gradually enlarged from the outside to the inside, forming a state of gradually decreasing strong pressure, so that the forming force of the overall part forms a total forming strain trend in which one side is tightened and the other parts are uniformly inward; the other three sides form a strong pressure belt 50mm outward along the overlapping edges, which is the second strong pressure area.

[0035] Preferably, the step 3 is: putting the third-order process type and the second-order process type together, and then comparing and optimizing, optimizing the inward retraction of the billet line in the drawbead area of ​​the third-order process type, so that all or all except the overlap edge with the wheel enter the second-order drawbead of the second-order process type, and constantly calculating the flow demand, while ensuring that the billet line of the third-order process type is within the second-order drawbead, the distance between the second-order drawbead and the drawbead on the third-order process type is the shortest, so as to save sheet material and reduce cost; after the optimization is completed, The second-order drawbeads are eliminated at the intersection of the lamp holder and the vehicle, and the elimination length is 25-35mm along the intersection line; then the ends of the drawbeads are blurred to form a cut-angle fracture; a flow gap is made for cut-angle debugging; at this time, a two-bead and two-fracture pattern of the overall drawbead is formed; the first-order drawbeads control the forming of the aluminum alloy sheet, and the first-order drawbeads and the second-order drawbeads jointly control the forming of the ordinary material sheet; the cut-angle fracture reserves a gap for cut-angle debugging, and the reverse drawing fracture leaves a gap for reverse drawing extension.

[0036] Preferably, step 4 comprises the following steps:

[0037] Step 4.1: Determine the width and height of the reverse drawing extension; the reverse drawing position extends outward from the reverse drawing fracture as the center, the left and right extension widths are to cover the entire wheel overlap area, and the front and rear extensions are bounded by the edge of the billet line that does not exceed the second-order process number. In this area, a product arc transition is made in the opposite direction of the parts in the wheel overlap area. The height of the reverse drawing arc is determined according to the undulation of the overall fender;

[0038] Step 4.2: Analyze and calculate the digital model of reverse drawing to confirm the smoothness of material feeding and the forming effect, batch calculate the forming state of reverse drawing height plus or minus 20%, and select the optimal state as the best choice for reverse drawing;

[0039] Step 4.3: The overall analysis process uses surface forming as the operation mode, and the reverse drawing area is subjected to a strong pressure treatment that gradually increases from the outside to the inside.

[0040] Preferably, during the program preprocessing in step 5, when the processing program is compiled, the first strong pressing zone is reserved for processing allowance from the outside to the inside, and a uniform allowance transition is made from the outer allowance to the inner allowance;

[0041] The reservation method is: outer allowance = 0.15*material thickness; inner allowance = 0;

[0042] The super finishing in step 5 is a super finishing mode for mold manufacturing, but note that an inclined axis processing method is used, and the tool path is a Z-shaped tool path from the outside to the inside.

[0043] Preferably, the rolling oil protection debugging in step 6 is to spray the rolling oil on the material of the convex part during the debugging of the aluminum alloy fender, select the convex parts on both sides of the lamp overlap and the side panel overlap for rolling oil spraying, spray 2 places first, and then try spraying combinations at different positions, check the state of the formed surface, select the surface quality combination with the best state, reduce the number of spraying points according to this combination, or expand the spraying area at a single place to connect the areas, and finally control the spraying amount within four places, and then install an oil spray pipe on the mold;

[0044] Preferably, the corner cutting debugging in step 6 is to concentrate the debugging difficulties in the area near the corner cutting fracture by reducing material, and then reduce friction by reducing the material near the corner cutting fracture, so as to achieve the forming of the difficult-to-form area of ​​the accessory and reduce the debugging workload; its mode is to remove the material outside the corner cutting fracture by 3 mm each time, compare the debugging effect, until the forming problem in the rear area is eliminated and the surface quality is stable, and then record the removal amount, modify the line shape of the blank again, and realize the solidification of the debugging result.

[0045] Preferably, step 7 includes the following contents: when trimming, a 3-8 mm margin is reserved for outward expansion, and at the same time, a 5-15 mm transition is made to the areas on both sides, leaving a cut-off overlap interface; and overall shaping is performed on the overlap area.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The present invention realizes the cold stamping die forming of aluminum alloy deep cavity fenders through surface forming control mode, floating forming, partition forming, corner cutting and debugging and other technical innovations, thereby solving the problem that aluminum alloy deep cavity fenders cannot be formed by cold stamping dies due to their surface quality and material properties, and greatly contributes to the advancement of vehicle lightweight technology.

[0048] 2. By controlling the reverse drawing extension of the mold surface, an S-shaped overall part forming trend is constructed. Combined with high-fit processing, the forming rebound and uncertainty of the deep-cavity fender are established as the main strain trend, thereby offsetting the impact of springback and uncertainty, creating a classic technical model for the forming of parts of similar shapes, which can be promoted and applied in various forming processes.

[0049] 3. Through the staged arrangement of drawbeads, different molding schemes can be perfectly arranged in the same mold, thus solving the problem that the molding of this type of parts is not compatible with the molding of other materials; through the surface molding control mode, the problem that drawbead control molding cannot achieve high surface quality accuracy is solved, so that the mold can be specialized and multi-functional, providing multiple possibilities for the optimal configuration of the vehicle, and greatly reducing the cost and cycle of vehicle development.

[0050] 4. The pressure source of floating molding can be disassembled and assembled, which solves the problem of key feature distortion caused by the difference in material properties of other materials, and establishes a mature technical solution for the mold facing multiple application modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0052] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the core concept of the present invention and the following embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The present application provides these embodiments to make the present application thorough and complete, and to fully express the scope of the present application to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0055] It should be noted that, in the description of this application, unless otherwise specified, the meaning of "several" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", "axial", "radial" and the like indicate positions or positional relationships only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on this application. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0056] In addition, the words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0057] It should also be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0058] All terms used in this application have the same meaning as those understood by those of ordinary skill in the art to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0059] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the corresponding technologies, methods, and equipment should be considered part of the specification.

[0060] In order to solve the technical problems raised in the background technology, the present invention has innovatively developed a method for manufacturing precision compatible molds for aluminum alloy automobile fenders through forming analysis and technical calculation of fender parts, especially deep cavity parts, multiple batches of repeated tests based on craftsmanship, and combined with CAE data deviation correction tests. This technology utilizes a high-fitting surface forming mode to improve the high surface quality and product precision of the product, and utilizes compatible material calculations to subdivide the forming control mode, while screening areas with large variables; utilizes floating forming and partitioned forming to solve the problem of poor forming performance of aluminum alloy materials, while realizing different forming methods of the same mold for compatible materials; utilizes a stepped arrangement of wide-distance draw ribs to achieve compatible surface forming while controlling the surface forming. The forming of compatible materials is differentiated to control the flow and reduce surface quality problems such as slip lines; the reverse stretching is used to control the surface to solve the deep cavity forming difficulty and secondary forming uncertainty of aluminum alloy materials; the rolling oil protection is used to further improve the surface quality; the shape characteristics of the fender are used to innovate the corner cutting adjustment to solve the cracking and uncontrollable springback problems in the large curvature deformation area; the secondary finishing is used to solve the splicing dimensional accuracy of complex small shapes at corners, so as to realize the development and application of precise compatible molds for automobile fenders, solve the problem that deep cavity fenders made of aluminum alloy cannot be formed by cold stamping molds, and realize the common mold manufacturing of compatible materials, reduce development costs and the workload of craftsmen for adjustment, shorten the cycle, and promote the development of lightweight automobile technology.

[0061] The present invention is based on repeated batch experiments by craftsmen, and through the combination of CAE technology and craftsmen's experience, it performs mold cold stamping forming of high-difficulty deep-cavity fenders. By utilizing compatible calculations, floating forming and partition forming of differential materials, step-by-step arrangement of drawbeads, surface control reverse drawing extension, high-fit processing, rolling oil protection and corner cutting debugging and other systematic technical innovations, high-precision mold cold stamping forming and manufacturing of deep-cavity automobile fenders made of aluminum alloy is achieved, and at the same time, the mold is made compatible with traditional materials, thereby making a new technical breakthrough in the difficulty of lightweighting the entire vehicle, and realizing low-cost and high-quality compatible cold stamping mold manufacturing. The present invention is suitable for the manufacture of compatible molds for aluminum alloy materials, steel plate materials, and magnesium-aluminum alloy sheet materials. The thickness of the plate used in the experiment of the present invention is 0.5-1.5mm.

[0062] The main process of the present invention is as follows Figure 1 As shown, the specific steps are as follows:

[0063] 1. Compatible material surface forming operation; this operation mainly uses CAE analysis to provide suitable process modeling for high-precision surface forming, while distinguishing the forming differences of different materials, selecting forming difficult areas and differentiated areas, and providing basic support for subsequent processes. The main operation methods are as follows:

[0064] 1.1. Perform a general forming analysis on the fender, and then select the high curvature area that cannot be formed for digital model optimization to reduce the high curvature risk points.

[0065] 1.2. Build a process digital model according to the aluminum alloy material. Use weak drawbead control during the construction process, that is, the drawbead should be as short as possible and appropriately widened, and the drawbead arrangement should only use a single-bead mode. The location of the drawbead should be close to the part contour, and repeated calculations are performed to find a location close to the part contour and where the drawbead can be smoothly placed. At the same time, pay attention to weakening or canceling some drawbeads in the wheel overlap area where the fender has small fluctuations. Then optimize the process adjustment, repeatedly calculate and continuously adjust, so that the difficult forming areas are concentrated on the top of the deep cavity and some difficult forming areas, thus obtaining the first-order process type.

[0066] 1.3, take the first-order process type as the basic process type for calculation, set the parameters to the parameters of the ordinary sheet material that needs to be compatible, and then expand the blank line. The expansion method is to first expand the overlap area between the part and the hood and the overlap area with the side panel, and the initial expansion amount is 30mm. Then, the expanded area is constructed with second-order draw ribs from the outside to the inside by 15mm. Calculate whether the ordinary sheet material can be fully formed. If it can be formed, this process type is a second-order process type; if it cannot be fully formed, extend the blank line to the headlight area and part of the wheel overlap area until the ordinary sheet material can be fully formed. Note that the wheel overlap area cannot be completely set with second-order draw ribs, and at least 75mm of the area without draw ribs should be left to form a reverse drawing fracture; at this time, the process type is a second-order drawing process type.

[0067] 2. Floating molding and partition molding: Floating molding and partition molding mainly solve the molding problems of deep cavity top and difficult-to-form area left over from the first-order process number. At the same time, the overall molding force optimization is implemented for the fender shape, while protecting the molding of key areas to form a total force change trend, reduce molding defects and the generation of burrs and slip lines. The steps are as follows:

[0068] 2.1. For the top difficult-to-form area, set rectangular or circular inserts according to the atmosphere that can cover 60%-80% of the internal area (the difficult-to-form area is an irregular shape, and a small area is required for easy forming). Establish floating forming blocks and pay attention to the edge lines of the floating blocks to divide them along the concave area or corner lines of the parts as much as possible.

[0069] 2.2. For other difficult-to-form convex areas, floating forming blocks are established by local segmentation, which is not limited by the coverage range, but must comply with the requirements of segmentation along concave areas or corner lines. At the same time, the number of segments should be as small as possible, and the minimum diameter or side length of the segments should not be less than 50mm, otherwise floating forming blocks cannot be formed.

[0070] 2.3. Add a bottom pressure source (usually a nitrogen cylinder) to the floating forming block to pre-form it in advance. The floating height is generally within 50mm of the overall height. CAE analysis can be used to calculate the height and corresponding pressure that can achieve full forming. The aluminum alloy material can be pre-formed before the overall forming, thereby solving the problem that deep cavities and difficult-to-form areas cannot be formed.

[0071] 2.4. When the material is changed to compatible ordinary material molding, remove the pressure source and cancel floating molding.

[0072] 2.5, Zoning molding; Due to the particularity of fender parts, their overall shape is wide at the top and narrow at the bottom, with a bulge in the middle, and the circumference needs to overlap with other products. There are complex features such as flanging at the overlapping parts, and the appearance of complex features greatly affects the consistency of the overall surface, thereby reducing the surface quality of the parts. Zoning molding is a combination of strong pressure and weak pressure, and the overall surface quality and local complex features are sequenced in order to ensure the surface quality and feature accuracy of the overall product; the zoning starts from the overlapping edge of the overlapping cover in terms of the overall shape, and goes up to the highest area of ​​the product. This area is the first strong pressure molding area, and key strong pressure molding is implemented in this area, and the gap is gradually enlarged from the outside to the inside, forming a state of gradually decreasing strong pressure, so that the molding force of the overall part forms a total molding strain trend of tightening on one side and evenly inwardly excessive in other parts; the other three edges form a strong pressure zone 50mm outward along the overlapping edge, which is the second strong pressure area, ensuring the molding of typical features while minimizing the impact on the surface quality of the internal overall smooth surface.

[0073] 2.6, the process type after floating molding and partition molding arrangement is a three-order process type.

[0074] 3. Arrange the drawbeads in stages; put the third-order process type and the second-order process type together, and then compare and optimize them. The blank line of the drawbead area of ​​the third-order process type is optimized and inwardly adjusted, so that all or all of it except the overlap edge with the wheel enters the second-order drawbead of the second-order process type, and the flow demand is continuously calculated. Under the condition of ensuring that the blank line of the third-order process type is within the second-order drawbead, the distance between the second-order drawbead and the drawbead on the third-order process type (this drawbead is the first-order drawbead) is minimized to save sheet material and reduce costs; after the optimization is completed, the second-order drawbead is eliminated at the intersection of the second-order drawbead lamp and the vehicle, and the elimination length is 25-35mm along the intersection line; then the end of the drawbead is over-virtualized to form a cut-angle fracture; and a flow gap is made for the cut-angle debugging. At this time, a two-rib and two-fracture pattern of the overall draw bead is formed; the first-order draw bead controls the forming of the aluminum alloy sheet, and the first-order draw bead and the second-order draw bead jointly control the forming of the ordinary material sheet; the angle cutting fracture reserves a gap for angle cutting debugging, and the reverse drawing fracture leaves a gap for reverse drawing extension.

[0075] 4. Reverse drawing and extension of the mold surface control; Reverse drawing and extension mainly solves the problems of insufficient molding, poor surface quality and uncertainty of secondary molding in deep cavity molding; Due to the properties of aluminum alloy materials, secondary molding has great uncertainty, and the molding margin is small, and the surface quality is not easy to control. Therefore, reverse drawing and extension are performed on the overlapping side of the part and the wheel cover, and the overall S-shaped modeling trend is formed in conjunction with the partition molding to reduce molding defects. At the same time, the rebound trend after cutting is inward, forming a trend that is conducive to overall molding and eliminating the influence of secondary molding uncertainty.

[0076] 4.1. Determination of the width and height of the reverse drawing extension. The reverse drawing position extends outward from the reverse drawing fracture as the center, and the left and right extension widths cover the entire wheel overlap area. The front and rear extensions are bounded by the edge of the blank line that does not exceed the second-order process number. In this area, a product arc transition is made in the opposite direction of the parts in the wheel overlap area. The height of the reverse drawing arc is determined according to the undulation of the overall fender. Generally, 100mm + the height from the highest point of drawing to the blank holder * 10% is used as the approximate reverse drawing height.

[0077] 4.2. Analyze and calculate the digital model of reverse drawing to confirm the smoothness of material feeding and the forming effect. Batch calculate the forming state of reverse drawing height plus or minus 20%, and select the optimal state as the best choice for reverse drawing.

[0078] 4.3. The overall analysis process takes surface forming as the operation mode, and the anti-drawing area is subjected to a strong pressure treatment that gradually increases from the outside to the inside to achieve its surface controllability.

[0079] 5. High-fitting processing: High-fitting processing is to improve the partition molding and surface molding control through the processing mode, provide adjustment amount for the later debugging of craftsman skills, avoid repeated adjustment and repeated processing, and consists of two parts: program preprocessing and super finishing;

[0080] 5.1, Program preprocessing, that is, when compiling the processing program, reserve the processing allowance for the first strong pressure zone from the outside to the inside, and make a uniform allowance transition from the outer allowance to the inner allowance; the reservation method is: outer allowance = 0.15*material thickness; inner allowance = 0.

[0081] 5.2, super finishing is the super finishing mode of mold manufacturing, but pay attention to the use of inclined axis processing method, and the tool path is from outside to inside Z-shaped tool path.

[0082] 6. Calendering oil protection debugging and corner cutting debugging;

[0083] 6.1. During the commissioning of aluminum alloy fenders, the rolling oil protection debugging is to spray the material of the convex parts with rolling oil. Because there are many convex parts, only the convex parts on both sides of the headlight overlap and the side panel overlap are selected for rolling oil spraying. First spray 2 places, and then try spraying combinations at different positions to check the state of the molding surface quality. Select the combination with the best surface quality. According to this combination, reduce the number of spraying points or expand the spraying area at a single place to connect the areas. Finally, control the spraying amount within four places, and then install an oil spray pipe on the mold (Note: rolling oil protection debugging is an experimental method for the debugging process and a supplementary method for high-difficulty molding. Generally, try to do process experiments before trimming the mold surface. Install an oil spray pipe only when high-quality molding is not possible in the end).

[0084] 6.2. Corner cutting debugging. Corner cutting debugging mainly concentrates the debugging difficulties in the area near the corner cutting fracture by reducing the material, and then reduces the friction by reducing the material near the corner cutting fracture, so as to realize the forming of the difficult-to-form area of ​​the accessory and reduce the debugging workload. The mode is to remove the material outside the corner cutting fracture by 3mm each time, and compare the debugging effect until the forming problem in the rear area is eliminated and the surface quality is stable. Then record the removal amount, modify the blank line shape again, and realize the solidification of the debugging result (Note: this method is not used when the current process forming can be completed perfectly).

[0085] 7. Secondary finishing is determined; in order to ensure the molding quality of each overlapping area of ​​the fender, during trimming and forming, for the overlapping edges of the vertical surfaces with complex shapes and complex corners, rough trimming is adopted first, then flanging and shaping, and then secondary finishing and punching are adopted to ensure that the dimensional accuracy of the area is improved while maximally protecting the subsequent processes from affecting the quality of the surface.

[0086] When trimming this type of area, reserve a 3-8mm margin outward, and at the same time make a 5-15mm transition on both sides to leave a cut overlap interface; shape the overlap area as a whole to ensure accuracy and quality; perform secondary cutting and trimming to ensure dimensional accuracy and surface quality.

[0087] 8. Finished product: After the whole process is completed, the mold can meet the factory requirements and can be shipped as a finished product after appearance processing and quality control.

[0088] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0089] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a precision compatible mold for an aluminum alloy automobile fender, characterized in that The following steps are involved: Step 1: Compatible material surface forming calculation: Use CAE analysis to provide suitable process modeling for high-precision surface forming, distinguish the forming differences of different materials, select the forming difficult areas and differentiated areas, and provide basic support for subsequent processes; Step 2: Floating molding and partition molding; Step 3: Arrange the drawbeads in stages; Step 4: Surface control reverse drawing and extension; reverse drawing and extension are performed on the overlapped side of the part and the wheel cover, and the overall S-shaped trend is formed in coordination with the partition molding; Step 5: High-fitting processing: Improve the partition molding and surface molding control through the processing mode, provide adjustment amount for the later debugging of craftsman skills, avoid repeated adjustment and repeated processing, and consist of two parts: program preprocessing and super finishing; Step 6: Calendering oil protection debugging and corner cutting debugging; Step 7: Secondary finishing and confirmation; during trimming and forming, for the overlapping edges of complex corners and facades with complex shape changes, the method of first rough trimming, then flanging and shaping, followed by secondary finishing and punching is adopted; Step 8: Finished product; The steps of step 2 are as follows: Step 2.1: For the top difficult-to-form area, set rectangular or circular inserts according to the atmosphere that can cover 60%-80% of the area inside, establish floating forming blocks, and pay attention to the edge lines of the floating forming blocks as much as possible along the concave area or corner lines of the parts; Step 2.2: For other difficult-to-form convex areas, a floating forming block is established by local segmentation, which is not limited by the coverage range, but must comply with the requirements of segmentation along the concave area or the corner line. At the same time, the number of segments should be as small as possible, and the minimum diameter or side length of the segment should not be less than 50mm, otherwise the floating forming block cannot be formed; Step 2.3: Add a bottom pressure source to the floating forming block, do pre-forming in advance, the floating height is generally within 50mm of the overall height, and use CAE to analyze and calculate the height and corresponding pressure that can achieve full forming; Step 2.4: When the material is changed to compatible ordinary material molding, remove the pressure source and cancel floating molding; Step 2.5: Zoning molding: Zoning molding is a method of combining strong pressure with weak pressure, and prioritizing the overall noodle quality and local complex features to ensure the noodle quality and feature accuracy of the overall product; Step 2.6: The process type after floating molding and partition molding is a three-stage process type; The partition forming described in step 2.5 is based on the overall shape, starting from the overlapping edge of the overlapping hair cover, and upward to the highest area of ​​the product. This area is the first strong pressure forming area, and the area is subject to focused strong pressure forming, and the gap is gradually enlarged from the outside to the inside, forming a state where the strong pressure gradually decreases, so that the forming force of the overall part forms a total forming strain trend of one side being tightened and other parts being uniformly inward; the other three sides form a strong pressure belt 50mm outward along the overlapping edge, which is the second strong pressure area; The step 3 is: putting the third-order process type and the second-order process type together, and then comparing and optimizing, optimizing the inward retraction of the blank line of the draw bead area of ​​the third-order process type, so that all or all of them except the overlap edge with the wheel enter the second-order draw bead of the second-order process type, and constantly calculating the flow demand, while ensuring that the blank line of the third-order process type is within the second-order draw bead, the distance between the second-order draw bead and the draw bead on the third-order process type is the shortest, so as to save sheet material and reduce cost; after the optimization is completed, the second-order The second-order drawbeads are eliminated at the intersection of the drawbead lamp holder and the vehicle, and the elimination length is 25-35mm along the intersection line; then the end of the drawbead is over-virtualized to form a cut-angle fracture; a flow gap is made for cut-angle debugging; at this time, a two-bead and two-fracture pattern of the overall drawbead is formed; the first-order drawbead controls the forming of the aluminum alloy sheet, and the first-order drawbead and the second-order drawbead jointly control the forming of the steel plate material sheet; the cut-angle fracture reserves a gap for cut-angle debugging, and the reverse drawing fracture leaves a gap for reverse drawing extension.

2. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 1, characterized in that: The main operation method of step 1 is as follows: Step 1.1: Perform a general forming analysis on the fender, and then select the high curvature area that cannot be formed for digital model optimization to reduce the high curvature risk points; Step 1.2: Construct a process digital model according to the aluminum alloy material. During the construction process, weak drawbead control is adopted, that is, the drawbead is as short as possible and appropriately widened, and the drawbead is arranged in a single-bead mode. The position of the drawbead should be close to the part contour, and the position close to the part contour and where the drawbead can be smoothly placed is repeatedly calculated to place the drawbead; then optimize the process adjustment, repeatedly calculate and continuously adjust, so that the difficult forming area is concentrated on the top of the deep cavity and some difficult-to-form areas, thereby obtaining the first-order process type; Step 1.3: Take the first-order process type as the basic process type for calculation, set the parameters to the parameters of the common sheet material that needs to be compatible, and then expand the blank line. The expansion method is to first expand the overlap area between the part and the bonnet and the overlap area with the side panel. The initial expansion amount is 30mm, and then construct the second-order draw ribs from the outside to the inside of the expanded area by 15mm. Calculate whether the common sheet material can be fully formed; if it can be formed, this process type is a second-order process type; if it cannot be fully formed, extend the blank line to the headlight area and part of the wheel overlap area until the common sheet material can be fully formed. At this time, the process type is a second-order drawing process type.

3. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 2, characterized in that: When performing step 1.2, it is necessary to pay attention to weakening or eliminating some draw ribs as much as possible in the wheel overlap area where the fender undulation is smaller; when performing step 1.3, it is necessary to pay attention that the wheel overlap area cannot be completely provided with second-order draw ribs, and at least 75 mm or more of the draw rib-free area should be left to form a reverse drawing fracture.

4. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 1, characterized in that The step 4 comprises the following steps: Step 4.1: Determine the width and height of the reverse drawing extension; the reverse drawing position extends outward from the reverse drawing fracture as the center, the left and right extension widths are to cover the entire wheel overlap area, and the front and rear extensions are bounded by the edge of the billet line that does not exceed the second-order process number. In this area, a product arc transition is made in the opposite direction of the parts in the wheel overlap area. The height of the reverse drawing arc is determined according to the undulation of the overall fender; Step 4.2: Analyze and calculate the digital model of reverse drawing to confirm the smoothness of material feeding and the forming effect, batch calculate the forming state of reverse drawing height plus or minus 20%, and select the optimal state as the best choice for reverse drawing; Step 4.3: The overall analysis process uses surface forming as the operation mode, and the reverse drawing area is subjected to a strong pressure treatment that gradually increases from the outside to the inside.

5. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 4, characterized in that: During the program preprocessing in step 5, when the processing program is compiled, the first strong pressure zone is reserved for processing allowance from the outside to the inside, and a uniform allowance transition is made from the outer allowance to the inner allowance; The reservation method is: outer allowance = 0.15*material thickness; inner allowance = 0; The super finishing in step 5 is a super finishing mode for mold manufacturing, but note that an inclined axis processing method is used, and the tool path is a Z-shaped tool path from the outside to the inside.

6. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 5, characterized in that: The rolling oil protection debugging in step 6 is to spray the rolling oil on the material of the convex part during the debugging of the aluminum alloy fender, select the convex parts on both sides of the lamp overlap and the side panel overlap for rolling oil spraying, spray 2 places first, and then try spraying combinations at different positions, check the state of the formed surface, select the best surface quality combination, reduce the number of spraying points according to this combination or expand the spraying area at a single place to connect the areas, and finally control the spraying amount within four places, and then install an oil spray pipe on the mold; The corner cutting debugging in step 6 is to concentrate the debugging difficulties in the area near the corner cutting fracture by reducing material, and then reduce friction by reducing the material near the corner cutting fracture, so as to achieve the forming of the difficult-to-form area of ​​the accessory and reduce the debugging workload; its mode is to remove the material outside the corner cutting fracture by 3 mm each time, compare the debugging effect, until the forming problem in the rear area is eliminated and the surface quality is stable, and then record the removal amount, modify the line shape of the blank again, and realize the solidification of the debugging result.

7. The method for manufacturing a precision compatible mold for an aluminum alloy automobile fender according to claim 6, characterized in that The step 7 includes the following contents: when trimming, a 3-8mm margin is reserved for outward expansion, and at the same time, a 5-15mm transition is made to the areas on both sides, leaving a cut-off overlap interface; and overall shaping is performed on the overlap area.

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