High-yield aluminum-magnesium alloy automotive panel die staging device and its forming method

Abstract

The present invention discloses a stepped device for an automobile panel die made of a high-yield aluminum-magnesium alloy and a forming method thereof. The device includes a slow-release blank holder, a floating blank holder, and a stepped forming die disposed between a lower die body and an upper die body. The slow-release blank holder is connected to the edge portion of the lower die body, the floating blank holder is connected to the edge portion of the upper die body, and the stepped forming die is connected to the middle position of the upper die body. The forming method includes stepped forming analysis, regional pressure calculation, self-pressure floating combination design, stepped pressure regulation, and hard point debugging. The present invention converts the traditional high-speed deep cavity forming mode into a slow-release shallow drawing forming mode in which the slow-release blank holder and the floating blank holder release pressure and lock the material, the stepped forming die performs first-order forming, the punch moves upward for second-order forming, and the punch and the die are pressed tightly for third-order forming, solving the problem of impossible cold stamping forming caused by the material properties of the high-yield strength aluminum-magnesium alloy, and providing the latest technical and device solutions for the application of high-quality lightweight materials in automobile parts.

Description

Technical Field

[0001] The present invention relates to the technical field of forming high-yield aluminum-magnesium alloy automotive body panels, and particularly to a stepped device for a high-yield aluminum-magnesium alloy automotive body panel die and a forming method thereof. Background Art

[0002] The rise and development of new energy vehicles is an important way for China's automotive technology to overtake on a curve, and also a key direction for the future development of the automotive industry. Along with the rise and development of new energy vehicles, vehicle lightweighting has become an important topic in the automotive industry. Lightweight vehicles will bring about a reduction in energy demand and an improvement in vehicle safety factor.

[0003] Currently, using aluminum-magnesium alloy to replace traditional sheets and using high-strength sheets to reduce the sheet thickness are two relatively mainstream directions for vehicle lightweighting. As an excellent and inexpensive lightweight material, aluminum-magnesium alloy has been highly favored during the development of automobiles. However, due to problems such as poor formability and weak material strength of aluminum-magnesium alloy materials, its application scope and application effect are greatly restricted. The emergence of high-yield new aluminum-magnesium alloy materials combines the performance of steel, exhibits excellent corrosion resistance and tolerance, and also has good lightweight characteristics, making it an ideal material for high-level lightweighting and vehicle high-endization.

[0004] However, aluminum-magnesium alloy materials are inherently difficult to form, and their cold stamping forming is greatly restricted. Moreover, the cold working forming performance of high-yield aluminum-magnesium alloy is even worse, unable to be formed twice, with poor ductility, easy to crack, and sensitive to stress. Therefore, it is difficult to form using the cold stamping mode, and continuous innovation and improvement of forming technology are required to solve the core problems of poor forming performance and difficult forming control caused by its sensitivity to stress.

[0005] It should be particularly noted that the above technical information is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of suggestion that the above technical information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0006] In view of the deficiencies in the above background art, the present invention proposes a stepped device for a high-yield aluminum-magnesium alloy automotive body panel die and a forming method thereof, which solves the technical problems of poor forming performance of high-yield new aluminum-magnesium alloy materials and the inability to form using a cold stamping die due to stress sensitivity.

[0007] The technical solution of the present application is as follows:

[0008] A stepped device for a high-yield aluminum-magnesium alloy automotive panel die, comprising a slow-release blank holder, a floating blank holder, and a stepped forming die disposed between a lower die body and an upper die body. The slow-release blank holder is connected to the edge portion of the lower die body, the floating blank holder is connected to the edge portion of the upper die body, and the stepped forming die is connected to the middle position of the upper die body.

[0009] Preferably, the slow-release blank holder, the floating blank holder, and the stepped forming die all include quick-adjusting pressure source components.

[0010] Preferably, the quick-adjusting pressure source component includes nitrogen gas springs arranged in rows on a quick-adjusting fixing plate through quick-lock screws. The nitrogen gas springs are connected to a pressure cylinder through a pressure-regulating air pipe. The pressure cylinder is connected with a cylinder pressure-regulating port, and the pressure cylinder is connected to the die body through a cylinder bracket.

[0011] Preferably, the quick-adjusting pressure source component of the slow-release blank holder is connected to the lower die body, and the nitrogen gas spring on the quick-adjusting pressure source component on the lower die body is connected to the blank holder for slow release; the quick-adjusting pressure source components of the floating blank holder and the stepped forming die are both connected to the upper die body, and the nitrogen gas springs on the two groups of quick-adjusting pressure source components on the upper die body are respectively connected to the blank holder for floating and the second-order forming body.

[0012] A forming method for a stepped device of a high-yield aluminum-magnesium alloy automotive panel die, comprising the following steps: stepped forming analysis, regional pressure calculation, self-pressure floating combination design, stepped pressure regulation, and hard point debugging;

[0013] When performing the stepped forming analysis, the part is subjected to multi-step forming calculation to simulate the material flow state and material extension condition of the product under the multi-step forming state, plan a suitable parting line and draw surface position, and at the same time, through multiple calculations, find the optimal stepped forming die area to achieve the theoretical feasibility of minimizing the drawing depth to the greatest extent;

[0014] The self-pressure floating combination design is aimed at the slow-release shallow drawing forming mode of the stepped forming die for the first-order forming, the second-order forming with the punch moving upward, and the third-order forming with the punch and die being clamped. The self-pressure floating combination design includes the slow-release blank holder design, the floating blank holder design, and the stepped forming die design.

[0015] Preferably, the operation steps of the stepped forming analysis are as follows: adjust the minimum height of the part without negative angles to determine the stamping direction; initially select the stepped forming die area; perform CAE calculation to determine the stepped forming die area; adjust the parting line and draw surface position to determine the primary process surface.

[0016] Preferably, the operation method for determining the stamping direction is as follows: Rotate the part along the long direction, check the overall negative angle state, find the lowest height state in the state without negative angle surfaces, and then, based on this state, rotate the part along the wide direction, search for the state without negative angles in a state lower than this lowest height state, set the lowest state as the stamping state of the part, and the over-height direction of this state is the stamping direction;

[0017] Preferably, the operation method for the initial selection of the stepped forming die area is as follows: Under the stamping direction, make a flattened surface along the concave contour for the large-area continuous concave area or short-interval dispersed concave area of the part, make the area of this surface as large as possible, and use 1-3 flattened planes to cover all areas greater than 10% of the stamping height state. At this time, the flattened surface area is the initial selection area of the stepped forming die area;

[0018] Preferably, the operation method for determining the stepped forming die area is as follows: In the first stage, perform CAE calculations on the state of the part after flattening the stepped forming die area, obtain the optimal forming parameters, and according to these parameters, perform secondary drawing calculations on the stepped forming die area, check the results. When the result state is poor, enlarge or reduce the stepped forming die area, so as to calculate the stepped forming die area in the optimal forming state, and determine this area as the stepped forming die area;

[0019] Preferably, the operation method for determining the primary process surface is as follows: Raise the position of the drawing surface, raise it by 5 mm at a time, and the drawing surface moves up during the raising state; when there is an interference area at this time, expand the position of the parting line, select the highest drawing surface position within 30 mm of the expanded parting line as the position of the drawing surface, and determine the digital model state at this time as the primary process surface.

[0020] Preferably, when designing the slow-release blank holder, first standardize the layout mode of the air ejector rods in the traditional mode of providing blank holding force by air ejector rods, arrange them as a straight line in the longest possible range, at the same time flatten the bottom surface of the blank holder into a plane, and also flatten the corresponding positions of the lower die and the blank holder to form an installation plane for the quick-adjustable pressure source assembly. Then install the quick-adjustable pressure source assembly on the installation plane, and adjust the quantity and position of the nitrogen springs according to the uniform distribution mode, so that the total pressure of the nitrogen springs reaches the calculated theoretical blank holding force and the positions of the nitrogen springs are evenly distributed. At this time, the quick-adjustable pressure source assembly and the blank holder constitute the slow-release blank holder.

[0021] Preferably, when designing the floating blank holder: Separate the upper die part corresponding to the slow-release blank holder, and then design the quick-adjustable pressure source assembly according to the mode corresponding to the slow-release blank holder to make it a blank holder corresponding to the slow-release blank holder. The combination of this blank holder and the quick-adjustable pressure source assembly is the floating blank holder.

[0022] Preferably, the stepped forming die is designed as follows: the stepped forming die area in the primary process digital model is dug out from the female die, set as a blank holder core mode, and then a quick-adjusting pressure source assembly is arranged at its bottom, and nitrogen gas springs are evenly arranged according to the theoretical pressure of the stepped forming die.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. Through the slow-release pressure stepped forming mode of the slow-release blank holder, floating blank holder, and stepped forming die, the present invention changes the traditional high-speed deep cavity forming mode in which the lower die of the mold is fixed and the upper die presses down rapidly with high speed and heavy load, and transforms it into a slow-release shallow drawing forming mode in which the slow-release blank holder and floating blank holder lock the material with slow-release pressure, the stepped forming die forms in the first stage, the punch moves up to form in the second stage, and the convex and concave dies are pressed tightly to form in the third stage. It successfully solves the problem of inability to cold stamping form caused by the material properties of high yield strength aluminum-magnesium alloy materials, reduces the forming extension amount, eliminates the influence of material sensitivity, and provides the latest technical and device solutions for the application of high-quality lightweight materials in automotive parts.

[0025] 2. Through the slow-release pressure scheme and stepped debugging, hard point debugging mode, the present invention adds a flexible debugging mode for the solidified design of large automotive molds and provides a general technology for cold stamping debugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention, the drawings required for description in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is the general assembly drawing of the local structure of the present invention, including: 1 quick-adjusting fixing plate, 2 nitrogen gas springs, 3 quick-lock screws, 4 pressure regulating air pipe, 5 pressure cylinder, 6 pressure regulating valve, 7 quick-adjusting pressure source assembly.

[0028] Figure 2 It is the drawing of the quick-adjusting pressure source assembly, including: 1 quick-adjusting fixing plate, 2 nitrogen gas springs, 3 quick-lock screws.

[0029] Figure 3 It is the part drawing of the quick-adjusting fixing plate, including: 1.1 nitrogen gas spring quick-installing T groove, 1.2 nitrogen gas spring quick-lock T groove.

[0030] Figure 4 It is the assembly drawing of the pressure cylinder and the pressure regulating valve, including: 5 pressure cylinder, 5.1 cylinder interface, 5.2 cylinder bracket, 5.3 cylinder pressure regulating port, 6 pressure regulating valve.

[0031] Figure 5It is a part drawing of a quick-lock screw, including: 3.1 butterfly screw, 3.2 quick-lock screw locking block, 3.3 quick-lock fixing block.

[0032] Figure 6 It is a structural diagram of the quick-lock screw locking block.

[0033] Figure 7 It is a flow chart of the forming method in the present invention. Specific embodiments

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the core concept of the present invention and the following embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0035] These embodiments are provided in this application to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the components of materials, numerical expressions and values described in these embodiments should be construed as merely exemplary, rather than as limitations.

[0036] It should be noted that in the description of this application, unless otherwise specified, "several" means greater than or equal to two; the orientation or positional relationships indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "axial", "radial", etc. are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of this application. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0037] In addition, the "first", "second" and similar terms used in this application do not denote any order, quantity or importance, but are only used to distinguish different parts. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range. Words such as "including" or "comprising" mean that the elements before this word cover the elements listed after this word, and do not exclude the possibility of also covering other elements.

[0038] It should also be noted that in the description of this application, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances. When it is described that a specific device is 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.

[0039] All terms used in this application have the same meanings as 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 a general dictionary, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such here.

[0040] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the corresponding technologies, methods, and devices should be regarded as part of the specification.

[0041] To solve the problems in the background art, through material forming experiments on high-yield new aluminum-magnesium alloy and comprehensive analysis of the forming process of automotive body panels (hereinafter referred to as parts), the present invention innovatively researches and develops a stepped device for high-yield aluminum-magnesium alloy automotive body panel dies and its forming method by continuously calculating the forming performance using stepped forming technology and combining the craftsman's skill correction mode of releasing pressure gradually. The device and method break through the traditional die forming mode, adopt a double-sided blank holding mode of a floating blank holder and a pressure-release blank holder in cooperation with a stepped forming die to reduce the overall forming depth, thereby reducing the cracking problem caused by poor forming performance. The self-strain pressure-release pressure source gradually releases the blank holding force technology is adopted to further expand the formability of the material, and a movable pressure source plate is constructed to adjust the pressure distribution, thereby making up for the problem that the material is highly sensitive to force and difficult to control. A voltage stabilizing and regulating device is adopted to adjust the pressure difference to control the feeding trend, thereby realizing the step-by-step forming process, realizing the gradual strengthening of the blank holding force and the precise control of the pressure distribution state, solving the problem that the high-yield new aluminum-magnesium alloy material has poor forming performance and cannot be formed by cold stamping dies due to force sensitivity, providing better material applications for the high-order lightweight of new energy vehicles, reducing costs and improving quality, and promoting the in-depth application of high-yield new aluminum-magnesium alloy.

[0042] Based on the batch repetitive tests of artisans, this invention utilizes batch debugging to obtain the variation trend of the forming speed accuracy of materials, and through the combination and calibration of CAE technology and artisans' experience, it invents a precise control and slow-release gradient pressure mode that realizes two-way blank holding to reduce the forming depth by innovatively dividing stages, converts high-speed heavy load into adjustable pressure difference and pressure layout, thereby realizing the stage division of the forming process, overcoming the forming defects of high-yield aluminum-magnesium alloy sheets, and achieving cold stamping die forming of high-yield aluminum-magnesium alloy materials with high precision. This invention is applicable to high-strength aluminum-magnesium alloy materials, aluminum alloy materials, and steel plate materials, and the strength of the test plates in this invention is 260 - 400 MPa.

[0043] The specific embodiments are as follows:

[0044] A staged device for high-yield aluminum-magnesium alloy automotive panel dies includes a slow-release blank holder, a floating blank holder, and a staged forming die disposed between the lower die body and the upper die body. The slow-release blank holder is connected to the edge part of the lower die body, the floating blank holder is connected to the edge part of the upper die body, and the staged forming die is connected to the middle position of the upper die body.

[0045] Preferably, as Figures 1 to 5 shown, the die body is not shown in the figure. The slow-release blank holder, the floating blank holder, and the staged forming die all include a quick-adjusting pressure source assembly. Preferably, the quick-adjusting pressure source assembly includes nitrogen gas springs 2 arranged in rows on a quick-adjusting fixing plate 1 through quick-lock screws 3. The nitrogen gas springs 2 are connected to a pressure cylinder 5 through a pressure-regulating air pipe 4. The pressure cylinder 5 is connected with a cylinder pressure-regulating port 5.3, and the pressure cylinder 5 is connected to the die body through a cylinder bracket 5.2.

[0046] Preferably, the quick-adjusting pressure source assembly of the slow-release blank holder is connected to the lower die body, and the nitrogen gas spring 2 on the quick-adjusting pressure source assembly on the lower die body is connected to the blank holder for slow release; the quick-adjusting pressure source assemblies of the floating blank holder and the staged forming die are both connected to the upper die body, and the nitrogen gas springs 2 on the two groups of quick-adjusting pressure source assemblies on the upper die body are respectively connected to the blank holder for floating and the second-stage forming body.

[0047] As a preferred embodiment of the staged device for high-yield aluminum-magnesium alloy automotive panel dies, as Figures 1 to 5As shown in the figure, the device mainly includes six parts: a quick-adjustment fixed plate 1, a nitrogen spring 2, a quick-lock screw 3, a pressure-regulating air pipe 4, a pressure cylinder 5, and a pressure-regulating valve 6. The nitrogen spring 2 (standard part) is installed on the quick-adjustment fixed plate 1. The card slot on the nitrogen spring 2 is inserted into the quick-adjustment fixed plate 1 through the quick-installation T-slot 1.1 of the nitrogen spring, and the position is adjusted according to the matching method and pressure requirements (described in part of the forming method). After the position adjustment is completed, the quick-lock fixed block 3.3 of the quick-lock screw 3 is inserted into the quick-lock T-slot 1.2 of the nitrogen spring, so that the quick-lock locking block 3.2 of the quick-lock screw clamps the edge of the nitrogen spring 2, and then the butterfly screw 3.1 is rotated to lock it, locking the position of the nitrogen spring 2. Then the nitrogen springs 2 are connected in series (common operating mode of nitrogen springs), thus completing the assembly of the quick-adjustment pressure source assembly 7.

[0048] The quick-adjustment pressure source assembly 7 is fixed to the lower die body of the mold with screws, and then a blank holder is placed on the upper part to form a slow-release blank holder; the quick-adjustment pressure source assembly 7 is fixed to the upper die body of the mold with screws, and a blank holder is installed on the upper part to form a floating blank holder. The quick-adjustment pressure source assembly 7 is fixed to the upper die body of the mold with screws, and a second-order forming body is installed on the upper part to form a stepped forming die (the slow-release blank holder, floating blank holder, and stepped forming die are the innovative modules of the present invention, which will be described in the forming method part). Thus, the three-part structure of the upper die, lower die, and blank holder of the traditional mold is changed to a five-part structure of the upper die, lower die, slow-release blank holder, floating blank holder, and stepped forming die; thereby converting the high-speed heavy-load one-time forming in the mold manufacturing process into a stepped forming mode that combines the two-way slow-release movement of the floating blank holder, the one-time forming of the stepped forming die, and the secondary forming of the upper and lower die bodies.

[0049] Connect the quick-adjustment pressure source assembly 7 under the slow-release blank holder to the cylinder interface 5.1 on the pressure cylinder 5 through the pressure-regulating air pipe 4, and connect the quick-adjustment pressure source assembly 7 under the stepped forming die to the cylinder interface 5.1 on the pressure cylinder 5 through the pressure-regulating air pipe 4; install the intake end of the pressure-regulating air pipe 4 on the pressure cylinder 5 through the cylinder interface 5.1, and connect the other end to the quick-adjustment pressure source assembly 7 under the floating blank holder through the pressure-regulating air pipe 4. Fix the pressure cylinder 5 to the mold body through the cylinder support 5.2, and fill nitrogen into the pressure cylinder 5 through the cylinder pressure-regulating port 5.3 to reach the required pressure. The whole device can be installed in the mold, thus changing the high-speed deep cavity forming mode of the traditional mold with the lower die fixed and the upper die quickly pressing down at high speed and heavy load, and converting it into a slow-release shallow drawing forming mode in which the slow-release blank holder and the floating blank holder release pressure and lock the material, the stepped forming die forms in the first stage, the punch moves up to form in the second stage, and the convex and concave dies are pressed tightly to form in the third stage. At the same speed and pressure, the cavity depth and drawing amount are greatly reduced, and the tensile strength of the material is improved, thus completing the cold stamping die forming of high-strength aluminum-magnesium alloy.

[0050] The forming method of the present invention needs to utilize the device of the present invention. Its forming method mainly calculates the shallow drawing amount through step-by-step forming analysis, determines the blank holding force and the first-order forming force through regional pressure calculation, arranges the quick-adjusting pressure source assembly 7 through self-pressure floating combination design, controls the forming refinement movement through step-by-step pressure regulation, and adjusts the pressure layout through hard point debugging, so as to realize the cold stamping die forming of high-strength aluminum-magnesium alloy.

[0051] A forming method for a stepped device of a high-yield aluminum-magnesium alloy automotive panel die, as Figure 7 shown, includes the following steps: I. Step-by-step forming analysis: mainly perform multi-step forming calculations on the part, so as to simulate the material flow state and material extension of the product under the multi-step forming state, plan the appropriate parting line and draw surface positions, and at the same time, through multiple calculations, find the optimal stepped forming die area to achieve the theoretical feasibility of minimizing the drawing depth to the greatest extent. The main operation methods are as follows:

[0052] 1. Adjust the minimum height of the part without negative angles to determine the stamping direction. The operation method is to rotate the part along the long direction, check the overall negative angle state, find the lowest height state in the state of the surface without negative angles, and then, based on this state, rotate the part along the width direction to find the state of the surface without negative angles in the state lower than this lowest height state, and set the lowest state as the stamping state of the part. The over-height direction of this state is the stamping direction.

[0053] 2. Initial selection of the stepped forming die area; under the stamping direction, make a flattened surface along the concave contour of the large-area continuous concave area or short-interval scattered concave area of the part, so that the area of this surface is as large as possible, and all areas greater than 10% of the stamping height state can be covered by 1-3 flattened planes. The flattened surface area at this time is the initial selection area of the stepped forming die area.

[0054] 3. CAE calculation. In the first stage, perform CAE calculation on the state of the part after flattening the stepped forming die area to obtain the optimal forming parameters. According to these parameters, perform secondary drawing calculation on the stepped forming die area, check the results, and when the result state is poor, enlarge or reduce the stepped forming die area, so as to calculate the stepped forming die area in the optimal forming state, and determine this area as the stepped forming die area.

[0055] 4. Adjust the parting line and draw surface positions; raise the draw surface position, raise it by 5 mm at a time, and the draw surface moves up in the raised state; when there is an interference area at this time, expand the parting line position, select the highest draw surface position within 30 mm of the expanded parting line, and determine it as the draw surface position. At this time, the digital model state is determined as the primary process surface.

[0056] II. Regional Pressure Calculation: Regional pressure calculation is mainly to determine the theoretical optimal slow-release pressure, which is divided into two parts: the theoretical blank-holding force and the theoretical multi-step forming die pressure;

[0057] 1. The theoretical blank-holding force is the blank-holding force calculated under the state of expanding the material yield strength by 8%;

[0058] 2. The theoretical multi-step forming die pressure is 60% of the forming force calculated by the secondary drawing;

[0059] III. Self-Pressure Floating Combination Design: Since the primary process surface is the process surface calculated and designed under the states of secondary drawing and the raised drawing surface, and due to the material properties of high-strength aluminum-magnesium alloy, it does not support secondary forming and has a high forming sensitivity. Using the traditional die design mode cannot achieve part forming. Therefore, it is necessary to design a multi-step forming structure to replace the secondary drawing and reduce the forming extension of the material, and design a floating blank-holder ring and a slow-release blank-holder ring to reduce the forming sensitivity of the material; change the traditional high-speed deep-cavity forming mode where the lower die of the die is fixed and the upper die presses down rapidly at high speed and heavy load during forming, and transform it into a slow-release shallow drawing forming mode where the slow-release blank-holder ring and the floating blank-holder ring release pressure and lock the material, the multi-step forming die forms in the first step, the punch moves up to form in the second step, and the punch and die are pressed tightly to form in the third step. This mode is the self-pressure floating combination design, and its main steps are as follows:

[0060] 1. Slow-Release Blank-Holder Ring Design: The slow-release blank-holder ring is an improvement of the traditional blank-holder ring design. First, standardize the layout mode of the air ejector rods in the traditional mode of using air ejector rods to provide the blank-holding force, arrange them as a straight line within the longest possible range, and at the same time flatten the bottom surface of the blank-holder ring into a plane, and also flatten the corresponding positions of the lower die and the blank-holder ring to form the installation plane of the quick-adjusting pressure source assembly 7. Then install the quick-adjusting pressure source assembly 7 on the installation plane, and adjust the quantity and position of the nitrogen gas springs 2 according to the uniform distribution mode so that the total pressure of the nitrogen gas springs 2 reaches the calculated theoretical blank-holding force and the positions of the nitrogen gas springs 2 are evenly distributed. At this time, the quick-adjusting pressure source assembly 7 and the blank-holder ring form the slow-release blank-holder ring.

[0061] 2. Floating Blank-Holder Ring Design: The function of the floating blank-holder ring is to cooperate with the slow-release blank-holder ring to convert the high-speed and heavy-load blank-holding force into a slow-release blank-holding force, so that the blank-holding force gradually increases during the forming process, thereby reducing the influence of the material forming sensitivity, and at the same time eliminating the forming problems caused by the raised position of the drawing surface. Its design method is to separate the upper die part corresponding to the slow-release blank-holder ring, and then design the quick-adjusting pressure source assembly 7 according to the corresponding mode of the slow-release blank-holder ring to make it a blank-holder ring corresponding to the slow-release blank-holder ring. The combination of this blank-holder ring and the quick-adjusting pressure source assembly 7 is the floating blank-holder ring.

[0062] 3. Design of stepped forming die: The stepped forming die is a convex die built inside the female die that is preferentially formed. Its function is to significantly reduce the height of the die, thereby reducing the material forming extension. Its design method is to dig out the stepped forming die area in the primary process digital model from the female die, set it as a blank holder core mode, then arrange a quick-adjusting pressure source component 7 at its bottom, and at the same time arrange nitrogen gas springs 2 evenly according to the theoretical pressure of the stepped forming die.

[0063] 4. When designing the stepped forming die, pay attention to its height state: When the nitrogen gas spring 2 is in the initial pressure state, its height should be 30 - 70% higher than the stepped forming die surface height of the female die surface (selected according to the stroke of the nitrogen gas spring), and it is flush with the female die surface in the nominal pressure state.

[0064] 5. The design of other parts of the die is the same as that of traditional dies.

[0065] IV. Stepped pressure regulation; Stepped pressure regulation is a debugging process to achieve the best floating forming and stepped forming effects by adjusting the pressure after the die is manufactured. It can control the feeding trend and enlarge the forming margin; the main steps are as follows:

[0066] 1. Pressure balance; Fill the pressure cylinder 5 with nitrogen gas so that its pressure reaches the nominal pressure according to the overall arrangement of the device of the present invention inside the die. The function of the pressure cylinder 5 is to connect the nitrogen gas springs in series through the pressure regulating air pipe 4, so as to ensure the uniform pressure of each nitrogen gas spring 2 in the quick-adjusting pressure source component 7 and maintain the pressure stability for a long time, thereby avoiding forming problems caused by uneven pressure.

[0067] 2. Floating pressure sub-control debugging: Floating pressure sub-control debugging is to adjust the pressure difference between the floating blank holder and the slow-release blank holder through the pressure regulating valve 6, so that the direction of the slowly released pressure during the forming process is determined to be weak at the top and strong at the bottom, and the pressure slowly increases from top to bottom. At the same time, a uniformly distributed blank holding force with an active range is formed by adjusting the pressure difference; the adjustment method is to adjust the pressure of the floating blank holder in the initial state to 60% of the pressure of the slow-release blank holder through the pressure regulating valve 6, and then increase the pressure by 5% each time, so as to select the best forming state and determine the floating pressure of the floating blank holder based on this state.

[0068] 3. Generally, the nominal pressure of a single nitrogen gas spring 2 connected in series in the stepped forming die is the same as the pressure of the pressure cylinder 5, and no pressure regulating valve 6 is added. When defects occur during forming, the pressure regulating valve 6 can be added to the stepped forming die according to the pressure regulating method of floating pressure sub-control debugging and debugged in the same way, and the pressure without defects is selected to complete the pressure adjustment of the stepped forming die.

[0069] V. Hard Point Debugging Hard point debugging is to adjust the position of the nitrogen spring 2. It is a debugging method to eliminate small forming defects through an unbalanced pressure mode. This method can further eliminate the sensitivity of material forming and eliminate defects. The main steps are as follows: According to the position of the forming defect, select the nitrogen spring 2 near the defect, loosen the butterfly screw 3.1 of the quick-lock screw 3, then move the position of the nitrogen spring 2 on the quick-adjust fixing plate 1, and then tighten the butterfly screw 3.1 to continue fixing the nitrogen spring 2. Adjust the defect state by creating unbalanced pressure until the defect is eliminated.

[0070] VI. Finished Product After the overall process is completed, the mold can meet the factory requirements. After surface treatment and quality improvement, it can be shipped as a finished product.

[0071] The details not described in this invention are all conventional technical means well known to those skilled in the art.

[0072] The above content shows and describes the basic principles, main features and the beneficial effects of the present invention. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high yield aluminum-magnesium alloy automobile cover mold grading device, characterized by: It includes a slow-release blank holder ring, a floating blank holder ring and a step-shaped forming die arranged between the lower die body and the upper die body, wherein the slow-release blank holder ring is connected to the edge of the lower die body, the floating blank holder ring is connected to the edge of the upper die body, and the step-shaped forming die is connected to the middle of the upper die body; The slow-release blank holder, floating blank holder, and step-by-step forming die all include a quick-adjustment pressure source assembly, through which the first-step forming of the step-by-step forming die, the second-step forming of the convex die moving upward, and the third-step forming of the convex and concave dies pressing together are performed. The quick-adjustment pressure source assembly comprises nitrogen springs (2) arranged in a row on a quick-adjustment fixing plate (1) via quick-locking screws (3); the nitrogen springs (2) are connected to a pressure cylinder (5) via a pressure-regulating air pipe (4); the pressure cylinder (5) is connected to a cylinder pressure-regulating port (5.3); and the pressure cylinder (5) is connected to the mold body via a cylinder bracket (5.2); The quick-adjusting pressure source assembly of the slow-release blank holder is connected to the lower die body, and the nitrogen spring (2) on the quick-adjusting pressure source assembly on the lower die body is connected to the blank holder for slow release; the quick-adjusting pressure source assembly of the floating blank holder and the quick-adjusting pressure source assembly of the step-forming die are both connected to the upper die body, and the nitrogen springs (2) on the two groups of quick-adjusting pressure source assemblies on the upper die body are respectively connected to the floating blank holder and the second-step forming body.

2. A molding method of a high yield aluminum-magnesium alloy automobile cover mold step device, characterized in that The following steps are adopted to design the high yield aluminum-magnesium alloy automobile cover mold hierarchical device described in claim 1: hierarchical forming analysis, regional pressure calculation, self-pressure floating combination design, hierarchical pressure regulation, and hard point debugging; When performing the step-by-step forming analysis, the parts are subjected to multi-step forming calculations to simulate the material flow state and material extension of the product under the multi-step forming state, plan the appropriate parting line and drawing surface position, and find the best step-by-step forming die area after multiple calculations to achieve the theoretical feasibility of minimizing the drawing depth; The self-pressure floating combination design is aimed at the slow-release shallow drawing forming mode of the first-stage forming of the step-by-step forming die, the second-stage forming of the punch moving up, and the third-stage forming of the punch and concave dies pressing together. The self-pressure floating combination design includes a slow-release edge holder ring design, a floating edge holder ring design, and a step-by-step forming die design.

3. The high yield aluminum-magnesium alloy automobile cover mold step-by-step forming method according to claim 2, characterized in that: The operation steps of the step-by-step forming analysis are as follows: adjust the minimum height of the part without negative angles to determine the stamping direction; initially select the step-by-step forming die area; perform CAE calculations to determine the step-by-step forming die area; adjust the parting line and the drawing surface position to determine the primary process profile.

4. The high yield aluminum-magnesium alloy automobile cover mold step-by-step forming method according to claim 3, characterized in that: The operation method for determining the stamping direction is: rotate the part along the length direction, check the overall negative angle state, find the lowest height state in the state of no negative angle profile, and then based on this state, rotate the part along the width direction, find the state of no negative angle less than this lowest height state, set the lowest state as the stamping state of the part, and the degree direction of this state is the stamping direction; The operation method for the initial selection of the step-by-step forming die area is as follows: in the stamping direction, a large-area continuous concave area or a short-interval dispersed concave area of ​​the part is flattened along the concave contour to make the surface area as large as possible, and 1-3 flattened planes can be used to cover all areas larger than 10% of the stamping height state. At this time, the flattened surface area is the initial selection area of ​​the step-by-step forming die area; The operation method for determining the step-by-step forming die area is as follows: in the first stage, CAE calculation is performed on the state of the part after the step-by-step forming die area is flattened to obtain the optimal forming parameters, and according to the parameters, secondary drawing calculation is performed on the step-by-step forming die area to check the results, and when the result state is not good, the step-by-step forming die area is enlarged or reduced, so as to calculate the step-by-step forming die area under the optimal forming state, and this area is determined as the step-by-step forming die area; The operation method for determining the primary process profile is: raising the drawing surface position by 5 mm at a time, and moving the drawing surface upward in the raised state; at this time, if there is an interference area, the parting line position is expanded, and the highest drawing surface position within 30 mm of the parting line expansion is selected to be determined as the drawing surface position. At this time, the digital model state is determined as the primary process profile.

5. The high yield aluminum-magnesium alloy automobile cover mold step-by-step forming method according to any one of claims 2 to 4, characterized in that: When designing the slow-release blank holder ring, firstly, the arrangement pattern of the gas ejector rod in the mode of providing the blank holder force of the traditional gas ejector rod is standardized, and it is arranged in a straight line over the longest range possible, and at the same time, the bottom surface of the blank holder ring is flattened into a plane, and the corresponding positions of the lower mold and the blank holder ring are also flattened to form an installation plane for the quick-adjustment pressure source assembly, and then the quick-adjustment pressure source assembly is installed on the installation plane, and the number and position of the nitrogen springs are adjusted according to the uniform distribution mode, so that the total pressure of the nitrogen springs reaches the calculated theoretical blank holder force, and the positions of the nitrogen springs are evenly distributed. At this time, the quick-adjustment pressure source assembly and the blank holder ring constitute a slow-release blank holder ring.

6. The high yield aluminum-magnesium alloy automobile cover mold step-by-step forming method according to any one of claims 2 to 4, characterized in that: When designing the floating blank holder ring: separate the upper mold part corresponding to the slow-release blank holder ring, and then design the quick-adjust pressure source assembly according to the pattern corresponding to the slow-release blank holder ring, so that it becomes a blank holder ring corresponding to the slow-release blank holder ring. The combination of this blank holder ring and the quick-adjust pressure source assembly is the floating blank holder ring.

7. The high yield aluminum-magnesium alloy automobile cover mold step-by-step forming method according to claim 6, characterized in that: The step-by-step forming mold is designed as follows: the step-by-step forming mold area within the primary process number is dug out from the concave mold, set to a core pressing mode, and then a quick-adjusting pressure source assembly is arranged at the bottom thereof, and nitrogen springs are evenly arranged according to the theoretical step-by-step forming mold pressure.

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