Skin forming die and method

Abstract

The invention relates to the technical field of high-end equipment manufacturing, in particular to a skin forming die and method.The die comprises a lower die and an upper die, a first reinforcing rib is arranged on the top face of a blank holder, and the first reinforcing rib extends along the contour line of the side portion of a product male die; a second reinforcing rib is arranged on the top face of the first reinforcing rib in the area corresponding to the product male die closing-in section, and the plane trend of the second reinforcing rib is consistent with the outline arc line of the product male die closing-in section. A product cavity matched with the product male die is formed in the bottom of the upper die, and rib grooves used for containing the first reinforcing ribs and the second reinforcing ribs during die assembly are formed in the sides of the product cavity. According to the invention, by arranging the reinforcing rib structures which are coordinated in the subareas on the blank holder, redundant plates generated due to sudden change of the cross section in the closing-in area can be conveniently guided and promoted to bulge orderly, local accumulation is effectively relieved, generation of wrinkles is remarkably reduced, and thus the technical problem that serious wrinkles of materials are easily caused at the closing-in section of a traditional die is solved.

Description

Technical Field

[0001] This invention relates to the field of high-end equipment manufacturing technology, and in particular to a skin forming mold and method. Background Technology

[0002] In the aerospace field, nickel-based superalloys are widely used in the manufacture of key skin structures such as engine intermediate sections and combustion chamber casings due to their excellent high-temperature strength and oxidation resistance. These parts typically have complex geometric features that transition from straight sections to tapered sections, with large surface depths and dramatic curvature changes. During the overall hot drawing process, the sheet metal must undergo significant non-uniform flow and local compressive deformation.

[0003] In existing technologies, a planar blank holder ring is commonly used in conjunction with an integral punch for one-time thermoforming. However, when the blank flows through the closing area, the abrupt change in cross-section causes the material to accumulate rapidly. The traditional blank holder structure cannot provide differentiated constraints, resulting in the excess sheet material folding disorderly under the action of compressive principal stress, forming severe wrinkling defects. Summary of the Invention

[0004] In view of this, the present invention proposes a skin forming mold and method, which actively guides the excess sheet material in the closing area to bulge in a controlled manner through a zoned and coordinated reinforcing rib structure, effectively alleviating material accumulation, significantly suppressing wrinkling, and avoiding the risk of cracking, thereby solving the technical problem that traditional forming molds easily lead to severe wrinkling of products.

[0005] The technical solution of this invention is implemented as follows: On one hand, the present invention provides a skin forming mold, comprising a lower mold and an upper mold, wherein, The lower die is provided with a product punch at the top and a pressure ring surrounding the product punch; The top surface of the pressure ring is provided with a first reinforcing rib, which extends along the contour line of the side of the product punch. In the area corresponding to the product punch closing section, the top surface of the first reinforcing rib is provided with a second reinforcing rib, the plane direction of the second reinforcing rib is consistent with the outline arc of the product punch closing section, and its cross-section is U-shaped. The bottom of the upper mold is provided with a product cavity that mates with the product punch, and the side of the product cavity is provided with a rib groove for accommodating the first reinforcing rib and the second reinforcing rib when the mold is closed.

[0006] Based on the above technical solutions, preferably, the lower mold includes a mold base, a vertical plate, and a bottom plate, wherein, The vertical plate slides vertically through the mold base, with the pressure ring fixedly connected to its upper end and the base plate fixed to its lower end; The product punch is fixed to the top of the mold base.

[0007] Based on the above technical solutions, preferably, two vertical plates are provided and symmetrically arranged on both sides of the product punch.

[0008] Based on the above technical solutions, preferably, the mold base has an inner cavity, wherein, The base plate is located within the inner cavity; The bottom of the inner cavity is provided with a pin inlet / outlet hole that runs vertically through it.

[0009] Based on the above technical solutions, preferably, the lower mold further includes a limiting plate, wherein, Two limiting plates are provided and are symmetrically arranged on both sides of the base plate; The side of the limiting plate makes sliding contact with the side of the base plate.

[0010] Based on the above technical solutions, preferably, the first reinforcing rib is provided in two parts and is symmetrically arranged on both sides of the product punch.

[0011] Based on the above technical solutions, preferably, the height of the second reinforcing rib gradually increases from the straight end side to the closed end side along the contour arc of the product punch closing section.

[0012] Based on the above technical solutions, preferably, the top surface of the second reinforcing rib is provided with damping grooves, wherein... The damping texture extends perpendicularly to the contour arc of the product punch closing section.

[0013] Based on the above technical solutions, preferably, the top surface of the first reinforcing rib is provided with guide patterns, wherein... The direction of the flow guide pattern is parallel to the outline of the straight section of the product punch.

[0014] On the other hand, the present invention also provides a skin forming method, using the mold described above, comprising the following steps: S1. After heating the flat blank to the thermoforming temperature, place it on the pressure ring and cover the top of the product punch; S2. Drive the upper die downward to close the die, and perform the first deep drawing of the blank until the product surface height reaches 40%~60%; S3. Open the mold, take out the semi-formed blank, and place it in a vacuum furnace for solution treatment. The solution temperature is 1050~1120℃, and the holding time is 15~30 minutes. S4. Place the solution-treated blank back onto the pressure ring, and drive the upper die downward to close the die again to complete the remaining deep drawing until the blank completely fits the forming surface of the product punch.

[0015] The skin forming mold and method of the present invention have the following advantages over the prior art: (1) By setting a first reinforcing rib extending along the contour line of the product punch on the pressure ring, and a second reinforcing rib arranged in the corresponding contour arc in the closing section area with a U-shaped cross section, the blank is subject to zoned differential constraints: the first reinforcing rib guides the material to flow smoothly along the predetermined path, while the second reinforcing rib, with its U-shaped cross section structure, induces the excess sheet material caused by the abrupt change in cross section to undergo orderly plastic bulging upward along the groove, rather than disordered folding, thereby fundamentally alleviating material accumulation, significantly suppressing the problem of wrinkling in the closing area, and improving product quality.

[0016] (2) By setting the height of the second reinforcing rib to gradually increase from the straight end to the closed end along the contour of the punch section of the product, it is easier to match the distribution law of the increasing accumulation of material during the flow process, so as to realize the gradient enhancement of constraint stiffness; the damping texture set on its top surface is perpendicular to the arc of the closed end contour, which effectively improves the lateral resistance to compression deformation and further suppresses instability and wrinkling. At the same time, the guide texture on the top surface of the first reinforcing rib is parallel to the contour line of the straight end, which reduces the interface friction between the blank and the pressure ring and promotes the smooth flow of material. The three work together to balance strong constraint and low resistance, and greatly improve the forming stability and surface quality.

[0017] (3) By adopting the strategy of first drawing to 40%–60% height and then intermediate solid solution, the work hardening caused by the initial deformation of high temperature alloy is effectively eliminated and the material plasticity is restored; during the second drawing, the bulging guidance function of the reinforcing rib is combined to avoid cracking or severe wrinkling caused by single large deformation, which greatly improves the overall forming qualification rate of deep cavity skin parts. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a side view of a skin forming mold according to the present invention; Figure 2 for Figure 1 Sectional view along axis AA; Figure 3 This is a 3D view of the lower mold area; Figure 4 This is a 3D view of the upper mold area; Figure 5 This is a top view of the pressure ring; Figure 6This is a perspective view of a typical skin part formed according to the present invention; In the diagram: 1. Lower mold; 2. Upper mold; 11. Product punch; 12. Pressure ring; 13. Mold base; 14. Vertical plate; 15. Base plate; 16. Limiting plate; 21. Product cavity; 22. Rib groove; 121. First reinforcing rib; 122. Second reinforcing rib; 1301. Inner cavity; 1302. Ejector pin inlet / outlet hole; 12101. Guide pattern; 12201. Damping pattern. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0026] like Figure 1-5 As shown, the skin forming mold and method of the present invention are applicable to the hot forming of thin-walled skin parts with curved surfaces made of nickel-based superalloys such as GH4169 and Inconel 718, and are particularly suitable for... Figure 6 The illustrated skin product features complex geometric characteristics such as partial tapering, hyperbola, and significant depth. The specific embodiments of the invention will now be described in detail with reference to the accompanying drawings.

[0027] The present invention provides a skin forming mold comprising a lower mold 1 and an upper mold 2. The lower mold 1 is mounted on a hydraulic platform of a hydraulic device, and the upper mold 2 is mounted on a hydraulic rod of the hydraulic device. The mold closing and opening actions are achieved by the hydraulic device. A vertically arranged lower ejector cylinder (as an ejector rod mechanism, also known as an ejector pin mechanism) is provided below the hydraulic platform to drive the pressure ring 12 to rise and fall.

[0028] The lower die 1 has a product punch 11 at its top, and a blank holder 12 is disposed on the top of the lower die 1 and arranged around the product punch 11. The top surface of the blank holder 12 has a first reinforcing rib 121, which extends along the contour line of the side of the product punch 11, and is used to provide circumferential constraint and guidance for the flow of the blank in the early stage of deep drawing, ensuring that the material flows smoothly along the predetermined path. In the area corresponding to the closing section of the product punch 11, the top surface of the first reinforcing rib 121 is further provided with a second reinforcing rib 122, whose planar orientation is consistent with the contour arc of the closing section of the product punch 11, and whose cross-section is U-shaped. This U-shaped structure not only provides local high rigidity support, but also induces the excess sheet material caused by the abrupt change in cross-section to undergo orderly plastic bulging upwards along it, effectively alleviating material accumulation and significantly suppressing wrinkling defects in the closing area.

[0029] The bottom of the upper mold 2 is provided with a product cavity 21 that cooperates with the product punch 11. The side of the product cavity 21 is provided with a rib groove 22 for accommodating the first reinforcing rib 121 and the second reinforcing rib 122 when the mold is closed, so as to avoid interference.

[0030] In the above structure, the lower mold 1 includes a mold base 13, a vertical plate 14, and a base plate 15. The vertical plate 14 slides vertically through the mold base 13, with a pressure ring 12 fixedly connected to its upper end and the base plate 15 fixed to its lower end. The product punch 11 is fixed to the top of the mold base 13.

[0031] Specifically, two upright plates 14 are provided and symmetrically arranged on both sides of the product punch 11 to ensure smooth movement of the pressure ring 12. The mold base 13 is fixed on the hydraulic table and has an inner cavity 1301, in which the base plate 15 is located. A pin inlet / outlet hole 1302 is provided vertically through the bottom of the inner cavity 1301. In the area below the pin inlet / outlet hole 1302, a countersunk hole is provided on the hydraulic table, in which the lower ejector cylinder, serving as the ejector mechanism, is installed. When it is necessary to lift the pressure ring 12, the piston rod of the lower ejector cylinder extends upward, passes through the pin inlet / outlet hole 1302, enters the inner cavity 1301, and pushes the base plate 15 to rise. The base plate 15 then drives the upright plate 14 and the pressure ring 12 to rise synchronously.

[0032] In addition, the lower mold 1 also includes two limiting plates 16 symmetrically arranged on both sides of the base plate 15, whose sides slide in contact with the sides of the base plate 15 to limit the lateral displacement of the base plate 15 and improve the stability of the system.

[0033] In the above structure, there are two first reinforcing ribs 121, which are symmetrically arranged on both sides of the product punch 11 and match the layout of the double vertical plates 14 to form a symmetrical flow channel to enhance the guiding effect.

[0034] Furthermore, the root surface of the first reinforcing rib 121 and the top surface of the pressure ring 12 form a smooth arc transition, as do the root surface of the second reinforcing rib 122 and the top surface of the first reinforcing rib 121. This transition structure avoids stress concentration and scraping of the blank surface caused by sharp corners, guides the sheet metal smoothly over the reinforcing rib steps during high-temperature deep drawing, prevents local jamming or micro-crack initiation, and further ensures forming stability and part surface integrity.

[0035] Based on the above structure, the height of the second reinforcing rib 122 gradually increases from the straight end to the closed end along the contour arc of the closing section of the product punch 11, for example, from 1.2 mm to 2.5 mm, to match the increasing distribution pattern of material accumulation during flow and achieve a gradient enhancement of constraint stiffness. Simultaneously, damping grooves 12201 are provided on the top surface of the second reinforcing rib 122, extending perpendicularly to the contour arc of the closing section of the product punch 11, to increase lateral resistance to compressive deformation and suppress material instability and wrinkling in the closing transition zone.

[0036] Furthermore, the damping texture 12201 consists of multiple textures, arranged at intervals along the contour arc of the product punch 11 closing section. The spacing between adjacent damping textures 12201 decreases from the start point to the end point of the arc, for example, from 2 mm to 0.8 mm. This gradually denser arrangement is adapted to the material stacking gradient, so that the excess sheet material is subjected to gradually enhanced lateral constraint during the bulging process, thereby guiding it to form a regular and continuous bulging band, reducing disordered folding and macroscopic wrinkling.

[0037] In addition, the top surface of the first reinforcing rib 121 is provided with a guide pattern 12101, the extension direction of which is parallel to the outline of the straight section of the product punch 11, which can effectively reduce the interface friction between the blank and the blank holder 12 and promote the smooth flow of material into the deep drawing area.

[0038] Furthermore, multiple flow guide lines 12101 are arranged in parallel, with their spacing increasing from the outer edge of the pressure ring 12 inward, for example, from 0.5mm to 1.2mm, to achieve flow control with strong inlet constraint and low outlet resistance, ensuring a smooth transition of the material when entering the deep drawing stage and avoiding deviation or wrinkles caused by excessive friction.

[0039] In the above structure, the gradient change in the height of the second reinforcing rib 122 works synergistically with the damping texture 12201 and the flow guide texture 12101: the height gradient matches the material packing distribution, realizing the adaptive adjustment of the constraint stiffness; the damping texture 12201 enhances the lateral anti-instability capability of the closing area, and the flow guide texture 12101 reduces the flow resistance of the straight section. The three together improve the stability of the forming process and the surface quality of the final part.

[0040] Based on the above-mentioned mold, the present invention also provides a skin forming method, comprising the following steps: S1. The mold is installed on a hydraulic device with a lower ejector cylinder. Before forming begins, the lower ejector cylinder lifts the base plate 15 and the blank holder 12 to a high position through the ejector pin inlet / outlet hole 1302 on the base plate 15; the high-temperature alloy flat blank is placed directly on the top of the blank holder 12, at which point the blank is in contact with the surfaces of the first reinforcing rib 121 and the second reinforcing rib 122 on the blank holder 12. Subsequently, the upper mold 2 begins to descend, closing in conjunction with the blank holder 12, clamping the blank between the product cavity 21 and the product punch 11. Since the blank is initially located on the blank holder 12, the reinforcing ribs participate in constraining the sheet metal from the initial forming stage; S2, the upper mold 2 continues to descend, and the blank gradually conforms to the product surface under hot conditions. During this process, the material flows smoothly into the cavity in the straight section area, while the material tends to accumulate locally in the transition area due to the shrinkage of the cross section. At this time, the second reinforcing rib 122, with its higher initial height than the straight section, forms preferential contact and local pressure on the blank in the transition area, restricting the disordered lateral flow of material; the first reinforcing rib 121 extends along the side contour line of the product punch 11, providing circumferential constraint to prevent early wrinkling; the height of the second reinforcing rib 122 gradually increases from the straight side to the transition side along the contour arc of the transition section of the product punch 11, matching the spatial distribution of material accumulation. S3. When the forming reaches 40%~60% of the product height, pause the deep drawing. After mold opening, eject the semi-formed blank through the ejector pin inlet / outlet hole 1302, and place it in a vacuum furnace for solution treatment. The solution treatment temperature is 1050~1120℃, and the holding time is 15~30 minutes to eliminate work hardening and restore the plasticity of the material, creating conditions for subsequent deep drawing. S4. After solution treatment, the blank is placed back on top of the blank holder 12, and the upper die 2 descends again to complete the remaining drawing stroke. After entering the severe deformation zone at the end, the material accumulates in large quantities due to the sharp reduction in cross-section. The U-shaped cross-section of the second reinforcing rib 122 forms an upward-opening guide groove, forcing the excess sheet material to bulge upward in a controlled manner along its direction. The top surface of the second reinforcing rib 122 is provided with damping texture 12201, whose extension direction is perpendicular to the contour arc of the end section of the product punch 11. Under high temperature and high pressure, it forms a non-uniform contact interface with the softened blank material, moderately increasing the local frictional resistance to stabilize the bulging position and inducing a micro-area strain gradient to suppress the secondary instability at the bulging front. At the same time, the top surface of the first reinforcing rib 121 is provided with flow guide texture 12101, whose extension direction is parallel to the contour line of the straight section of the product punch 11, reducing interface friction and promoting smooth material flow. Finally, the excess sheet material forms a regular and continuous bulging band under the dual guidance of geometric contour and surface topology, significantly reducing the risk of macroscopic wrinkling. S5. The material is completely attached to the forming surface of the product punch 11 to obtain an integral curved thin-walled skin without wrinkles, cracks, or welds; after the upper die 2 returns, the ejector cylinder pushes the base plate 15 and the pressure ring 12 upward through the ejector pin inlet and outlet hole 1302 to smoothly remove the forming part from the product punch 11. S6. The demolded product is sent to the subsequent cutting station, and excess waste is removed by laser cutting or mechanical punching equipment. The waste includes flange residue distributed along the outer edge of the pressure ring 12, and raised bands formed by controlled material bulging in the areas of the first reinforcing rib 121 and the second reinforcing rib 122, and finally a net-shaped high-temperature alloy skin part that conforms to the design profile is obtained.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A skin forming mold, characterized in that: Includes a lower mold (1) and an upper mold (2), wherein, The lower die (1) is provided with a product punch (11) at the top and a pressure ring (12) surrounding the product punch (11). The top surface of the pressure ring (12) is provided with a first reinforcing rib (121), which extends along the contour line of the side of the product punch (11); In the area corresponding to the closing section of the product punch (11), the top surface of the first reinforcing rib (121) is provided with a second reinforcing rib (122), the plane direction of the second reinforcing rib (122) is consistent with the contour arc of the closing section of the product punch (11), and its cross-section is U-shaped; The bottom of the upper mold (2) is provided with a product cavity (21) that cooperates with the product punch (11), and the side of the product cavity (21) is provided with a rib groove (22) for accommodating the first reinforcing rib (121) and the second reinforcing rib (122) when the mold is closed.

2. The skin forming mold as described in claim 1, characterized in that: The lower mold (1) includes a mold base (13), a vertical plate (14), and a base plate (15), wherein, The vertical plate (14) slides vertically through the mold base (13), with the pressure ring (12) fixedly connected to its upper end and the base plate (15) fixed to its lower end. The product punch (11) is fixed to the top of the mold base (13).

3. The skin forming mold as described in claim 2, characterized in that: Two upright plates (14) are provided and are symmetrically arranged on both sides of the product punch (11).

4. The skin forming mold as described in claim 2, characterized in that: The mold base (13) is provided with an inner cavity (1301), wherein, The base plate (15) is located in the inner cavity (1301); The bottom of the inner cavity (1301) is provided with a pin inlet / outlet hole (1302) that runs vertically through it.

5. A skin forming mold as described in claim 2, characterized in that: The lower mold (1) also includes a limiting plate (16), wherein, Two limiting plates (16) are provided and are symmetrically arranged on both sides of the base plate (15); The side of the limiting plate (16) slides in contact with the side of the bottom plate (15).

6. The skin forming mold as described in claim 1, characterized in that: Two first reinforcing ribs (121) are provided and are symmetrically arranged on both sides of the product punch (11).

7. A skin forming mold as described in claim 1, characterized in that: The height of the second reinforcing rib (122) gradually increases from the straight end to the closed end along the contour arc of the closed section of the product punch (11).

8. A skin forming mold as described in claim 1, characterized in that: The top surface of the second reinforcing rib (122) is provided with damping grooves (12201), wherein, The extension direction of the damping texture (12201) is perpendicular to the contour arc of the closing section of the product punch (11).

9. A skin forming mold as described in claim 1, characterized in that: The top surface of the first reinforcing rib (121) is provided with guide lines (12101), wherein, The extension direction of the guide pattern (12101) is parallel to the outline of the straight section of the product punch (11).

10. A skin forming method, using a mold as described in any one of claims 1 to 9, characterized in that: Includes the following steps: S1. After heating the flat blank to the thermoforming temperature, place it on the pressure ring (12) and cover the top of the product punch (11); S2. Drive the upper mold (2) downward to close the mold, and perform the first deep drawing of the blank until the product surface height reaches 40%~60%; S3. Open the mold, take out the semi-formed blank, and place it in a vacuum furnace for solution treatment. The solution temperature is 1050~1120℃, and the holding time is 15~30 minutes. S4. Place the solution-treated blank back onto the pressure ring (12), and drive the upper die (2) down to close the die again to complete the remaining deep drawing until the blank is completely attached to the forming surface of the product punch (11).

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