Sheet metal hydraulic forming device and method

Abstract

The present invention discloses a sheet metal hydraulic forming device and method, wherein the sheet metal liquid forming device includes an upper mold and a lower mold, wherein the upper mold includes an upper template, and a hydraulic forming mold containing a sheet metal workpiece is fixed to the bottom of the upper template; the lower mold includes a lower template and a lower support plate located around the lower template, the lower template and the lower support plate are slidably and sealedly connected, the upper surface of the lower support plate is higher than the upper surface of the lower template, and the upper surface of the lower template and the inner side wall of the lower support plate form a hydraulic chamber; when the upper and lower templates are closed, the upper template drives the lower support plate to move downward relative to the lower template, causing the liquid medium in the hydraulic chamber to move toward the surface of the sheet metal workpiece fixed to the bottom of the upper template, thereby generating hydraulic pressure. The present invention generates high pressure on the sheet metal workpiece by means of the volume change of the hydraulic chamber, thereby causing it to be hydraulically formed. The structure is simple and the operation is convenient, effectively reducing the cost of hydraulic forming and improving the efficiency of hydraulic forming.

Description

Technical Field

[0001] The present invention relates to the field of sheet metal hydraulic forming, and in particular to a sheet metal hydraulic forming device and method. Background Art

[0002] Currently, sheet metal hydroforming technology often relies on specialized hydraulic forming equipment to generate hydraulic pressure, which is then applied to form the sheet metal into the desired shape. This existing technology requires the purchase of new hydraulic forming equipment, resulting in high costs. Furthermore, hydraulic forming equipment requires a process of filling and pressurizing the liquid and then draining the liquid to release the pressure, resulting in long forming cycles and low forming efficiency.

[0003] Patent number CN112122438A discloses a liquid-filled forming mold and method for thin-walled sheet metal parts. However, the hydraulic forming mold must be installed on a CNC press with a liquid-filling function. A prefabricated blank is placed on a rubber bladder. The upper platform of the press moves downward, pressing the upper mold core against the upper surface of the lower mold core to form a closed chamber. Liquid is injected into the rubber bladder from an inlet through a booster attached to the press. Under the action of the liquid pressure, the blank outside the rubber bladder undergoes plastic deformation until the pressure in the booster reaches the preset pressure of the press program, ensuring that the blank is in contact with the upper and lower mold core surfaces, thereby completing the forming of the liquid-filled blank. This invention requires a CNC press with a liquid-filling function, which is costly and inefficient.

[0004] Patent No. CN109127851A discloses a hydraulic-based forming method for aluminum alloy thin plate parts. However, this technology uses a supercharger to pressurize the cavity, and the pressure range is limited (5MPa-50MPa). It also has the defects of high forming cost and low efficiency. Summary of the Invention

[0005] The present invention aims to address, at least to a certain extent, one of the problems in the related art. To this end, the present invention provides a sheet metal hydroforming device and method that utilizes the volume changes of a hydraulic chamber to generate high pressure on a sheet metal workpiece, thereby enabling hydroforming. This device and method have a simple structure and are easy to operate, effectively reducing the cost of hydroforming and improving its efficiency.

[0006] In order to achieve the above objectives, the present application adopts the following technical solution: a sheet metal hydraulic forming device, comprising:

[0007] an upper die, comprising an upper platen, wherein a hydroforming die containing a sheet metal workpiece is secured to the bottom of the upper platen;

[0008] A lower mold, comprising a lower mold plate and a lower supporting plate located around the lower mold plate, wherein the lower mold plate and the lower supporting plate are slidably and sealedly connected, an upper surface of the lower supporting plate is higher than an upper surface of the lower mold plate, and the upper surface of the lower mold plate and an inner side wall of the lower supporting plate form a hydraulic chamber;

[0009] When the upper and lower molds are closed, the upper mold drives the lower support plate to move downward relative to the lower mold, so that the liquid medium in the hydraulic chamber moves toward the surface of the sheet metal workpiece fixed to the bottom of the upper mold, forming hydraulic pressure.

[0010] Furthermore, a groove is provided on the upper surface of the lower template, and the groove and the inner side wall of the lower support plate form a hydraulic chamber.

[0011] Furthermore, the lower mold also includes a lower support plate insert, which is fixed to the inner side wall of the lower support plate, and the lower support plate insert is fixedly connected to the lower support plate, and the lower support plate insert is slidably and sealedly connected to the lower template.

[0012] Furthermore, a first sealing member is provided on the upper surface of the lower support plate insert, and when the upper template and the lower template are in a mold closing state, the first sealing member abuts against the upper template.

[0013] Furthermore, a second sealing member is provided on the inner side wall of the lower support plate insert.

[0014] Furthermore, a compression spring is provided at the bottom of the lower supporting plate, the bottom end of the compression spring is fixed to the forming platform, and the top end is fixed to the bottom of the lower supporting plate.

[0015] Furthermore, a guide column is provided on the outer edge of the lower support plate, and a socket adapted to the guide column is provided in the upper template.

[0016] Furthermore, a pressure sensor is provided at the bottom of the hydraulic chamber.

[0017] Furthermore, it also includes a control component and a drive component, the drive component is fixedly connected to the upper template, and can drive the upper template to move toward or away from the lower template; the control component is communicatively connected to the drive component and the pressure sensor; the control component calculates the volume of liquid medium required for the hydraulic forming of the sheet metal workpiece according to the target shape of the sheet metal workpiece, and controls the control component to drive the upper template to move downward to a corresponding stroke; the control component fine-tunes the stroke of the upper template according to the monitoring value of the pressure sensor.

[0018] A method for performing sheet metal hydroforming using the sheet metal hydroforming device as described above comprises:

[0019] A hydraulic forming die containing a sheet metal workpiece is fixed to the bottom of an upper die plate; a liquid medium is filled inside a hydraulic chamber; the upper die plate drives a lower support plate to move downward relative to the lower die plate, causing the liquid medium in the hydraulic chamber to move toward the surface of the sheet metal workpiece fixed to the bottom of the upper die plate, forming hydraulic pressure; and the sheet metal workpiece is forced to be hydraulically formed under the action of the hydraulic forming die and hydraulic pressure.

[0020] The above-mentioned technical solution provided by the embodiment of the present application has the following advantages compared with the existing technology: in the present application, the lower template and the lower support plate are slidably and sealedly connected, the upper surface of the lower support plate is higher than the upper surface of the lower template, the upper surface of the lower template and the inner wall of the lower support plate form a hydraulic chamber, and when the upper template and the lower template are closed, the upper template drives the lower support plate to move downward relative to the lower template, so that the liquid medium in the hydraulic chamber moves toward the surface of the sheet metal workpiece fixed at the bottom of the upper template, forming hydraulic pressure; the sheet metal workpiece is fixed in the hydraulic forming mold, and under the action of the liquid, the sheet metal workpiece is hydraulically formed in accordance with the hydraulic forming mold; the device of the present application has a simple structure and a convenient operation method, which effectively reduces the efficiency of hydraulic forming and reduces the cost of hydraulic forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] In the attached figure:

[0024] Figure 1 This is a schematic diagram of the structure when the upper mold and the lower mold are not closed in this application;

[0025] Figure 2 This is a schematic diagram of the structure of the upper mold and the lower mold when they are closed in this application;

[0026] Figure 3 A schematic diagram of the structure of one of the hydroforming dies;

[0027] Figure numbers: 11. Upper mold insert; 12. Sheet metal workpiece; 13. Upper mold plate; 14. Liquid medium; 21. Lower support plate insert; 22. Lower support plate; 23. Lower mold plate; 24. Pressure sensor; 25. Nitrogen spring; 26. First seal; 27. Second seal; 28. Guide column; 29. ​​Jack; 30. Aviation plug. DETAILED DESCRIPTION

[0028] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the technical solution and do not indicate that the mechanisms or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0029] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", "fixed", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0030] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, mechanisms, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0031] See also Figure 1-Figure 3 , the present application provides a sheet metal hydraulic forming device, comprising:

[0032] an upper die, comprising an upper die plate 13 , wherein a hydroforming die containing a sheet metal workpiece 12 is fixed to the bottom of the upper die plate 13 ;

[0033] The lower mold includes a lower mold plate 23 and a lower supporting plate 22 located around the lower mold plate 23. The lower mold plate 23 and the lower supporting plate 22 are slidably and sealedly connected. The upper surface of the lower supporting plate 22 is higher than the upper surface of the lower mold plate 23. The upper surface of the lower mold plate 23 and the inner side wall of the lower supporting plate 22 form a hydraulic chamber.

[0034] When the upper mold plate 13 and the lower mold plate 23 are closed, the upper mold plate 13 drives the lower support plate 22 to move downward relative to the lower mold plate 23, so that the liquid medium 14 in the hydraulic chamber moves toward the surface of the sheet metal workpiece 12 fixed at the bottom of the upper mold plate 13, forming hydraulic pressure.

[0035] In the present application, the lower template 23 and the lower support plate 22 are slidingly and sealingly connected, the upper surface of the lower support plate 22 is higher than the upper surface of the lower template 23, and the upper surface of the lower template 23 and the inner side wall of the lower support plate 22 form a hydraulic chamber. When the upper template 13 and the lower template 23 are closed, the upper template 13 drives the lower support plate 22 to move downward relative to the lower template 23, so that the liquid medium 14 in the hydraulic chamber moves toward the surface of the sheet metal workpiece 12 fixed at the bottom of the upper template 13, forming hydraulic pressure; the sheet metal workpiece 12 is fixed in the hydraulic forming mold, and under the action of the liquid, the sheet metal workpiece 12 is hydraulically formed in contact with the hydraulic forming mold; the device of the present application has a simple structure and a convenient operation method, which effectively reduces the efficiency of hydraulic forming and reduces the cost of hydraulic forming.

[0036] As a specific embodiment, an upper mold insert 11 is provided at the center of the upper mold plate 13 of the present application. The bottom of the upper mold insert 11 can be set as a hydraulic forming mold, or a separate hydraulic forming mold can be fixed to the bottom of the upper mold insert 11, so that an upper mold cavity is formed between the sheet metal workpiece and the hydraulic forming mold. Before the hydraulic pressure starts, the lower surface of the sheet metal workpiece is flush. After the hydraulic pressure starts, the sheet metal workpiece moves toward the inside of the upper mold cavity until it forms the same shape as the hydraulic forming.

[0037] The upper mold insert 11 is detachable relative to the upper mold plate 13, which is convenient for fixing the hydraulic forming mold. The sheet metal workpiece 12 is fixed under the hydraulic forming mold. When the lower surface of the sheet metal workpiece 12 is pressurized, it will move in accordance with the hydraulic forming mold to achieve hydraulic forming of the sheet metal workpiece 12. Figure 1 and Figure 3 As shown, the lower surface of the upper mold insert 11 is fixed with a concave and convex hydraulic forming die, and the initial shape of the sheet metal workpiece 12 is a flat plate structure; Figure 2 As shown, the sheet metal workpiece 12 after hydraulic forming moves toward the hydraulic forming die on the lower surface of the upper die insert 11. Under the action of the hydraulic forming die and hydraulic pressure, the sheet metal workpiece 12 is formed into a concave-convex shape consistent with the structure of the hydraulic forming die.

[0038] Specifically, the upper mold insert 11 and the upper mold plate 13 can be made of Cr12MoV material with a heat treatment hardness of HRC58-60 and a surface roughness of Ra0.2 to improve their wear resistance and service life.

[0039] As a specific embodiment, the lower mold plate 23 of the present application corresponds to the upper mold insert 11. A lower support plate 22 is provided on the periphery of the lower mold plate 23, and the position of the lower support plate 22 corresponds to the position of the upper mold plate 13. A lower support plate insert 21 is provided between the lower support plate 22 and the lower mold plate 23. The lower support plate insert 21 is provided to ensure the sealing of the hydraulic chamber. The lower support plate insert 21 and the lower support plate 22 are fixedly connected and move synchronously.

[0040] The upper surface of the lower template 23 is provided with a groove, which, together with the inner sidewall of the lower support plate 22, forms a hydraulic chamber. The hydraulic medium filled in the hydraulic chamber in this application can be an emulsion, hydraulic oil, or water. The specific shape of the groove can be designed according to actual use.

[0041] The lower mold further includes a lower support plate insert 21 , which is fixed to the inner side wall of the lower support plate 22 , and is fixedly connected to the lower support plate 22 , and is slidingly and sealingly connected to the lower mold plate 23 .

[0042] A first seal 26 is provided on the upper surface of the lower support plate insert 21. When the upper and lower mold plates 13 and 23 are in the closed mold state, the first seal 26 abuts the upper mold plate 13. A second seal 27 is provided on the inner sidewall of the lower support plate insert 21. In this application, the first seal 26 is made of a relatively high-hardness polyurethane rubber, while the second seal 27 is made of both polyurethane rubber and Teflon to ensure a system sealing performance of 100 MPa.

[0043] The lower stripping insert and the lower template 23 of this application are made of Cr12MoV material, with heat treatment hardness HRC58-60 and surface roughness Ra0.2 to improve their wear resistance and life.

[0044] As another specific embodiment, the present application may only set up the lower template 23 and the lower support plate 22, omit the lower support plate insert 21, and directly set the first seal 26 and the second seal 27 on the upper surface and inner wall of the lower support plate 22.

[0045] As a specific embodiment, a compression spring is provided at the bottom of the lower support plate 22, the bottom end of the compression spring is fixed to the forming platform, and the top end is fixed to the bottom of the lower support plate 22. In this application, the forming platform is the support base of the entire forming device, and a lower template 23 is fixed on the upper surface of the forming platform. The lower support plate 22 around the lower template 23 is fixed to the forming platform by a compression spring, that is, the lower template 23 is fixed relative to the forming platform, and the lower support plate 22 can slide relative to the lower template 23 and the forming platform. During the mold closing process, the lower template 23 is fixed, and the upper template 13 drives the lower support plate 22 to move downward, so that the liquid medium 14 inside the hydraulic chamber moves toward the sheet metal workpiece 12, applying hydraulic pressure to the sheet metal workpiece 12, so that it is hydraulically formed.

[0046] The specific compression spring may be a nitrogen spring 25 .

[0047] To ensure a smooth mold closing process, guide posts 28 are provided on the outer edge of the lower support plate 22, and sockets 29 are provided in the upper mold plate 13 to accommodate the guide posts 28. The bottom ends of the guide posts 28 are fixed to the upper surface of the forming platform, and the upper ends extend through the lower support plate 22. During the mold closing process, the guide posts 28 are aligned with the sockets 29, ensuring that the downward movement direction of the upper mold plate 13 is accurate and without deviation.

[0048] A pressure sensor 24 is provided at the bottom of the hydraulic chamber of the present application; the pressure sensor 24 is connected to an external power source via an aviation plug 30. The sheet metal hydraulic forming apparatus also includes a control assembly and a drive assembly. The drive assembly is fixedly connected to the upper plate 13 and can drive the upper plate 13 toward or away from the lower plate 23. The control assembly is in communication with the drive assembly and the pressure sensor 24. The control assembly calculates the volume of liquid medium 14 required for hydraulic forming of the sheet metal workpiece 12 based on its target shape and controls the control assembly to move the upper plate 13 downward by a corresponding stroke. The control assembly fine-tunes the formation of the upper plate 13 based on the monitoring value of the pressure sensor 24.

[0049] Please continue reading Figure 1-Figure 3 , the present application also provides a sheet metal hydraulic forming method, comprising the following steps:

[0050] A hydroforming die containing a sheet metal workpiece 12 is fixed to the bottom of an upper die plate 13, wherein an upper die insert 11 is provided in the middle of the upper die plate 13, the bottom of the upper die insert 11 is fixed to the hydroforming die, and the sheet metal workpiece 12 is fixed below the hydroforming die;

[0051] The hydraulic chamber is filled with a liquid medium 14 , and the filling amount of the liquid medium 14 can be determined according to the forming process of the sheet metal workpiece 12 .

[0052] The control component calculates the volume of liquid medium 14 required for the hydroforming of the sheet metal workpiece 12 based on the target shape, i.e., the shape after forming, and controls the control component to drive the upper plate 13 downward to a corresponding stroke, wherein the stroke of the upper plate 13 downward movement is equal to the stroke of the upper plate 13 contacting the liquid medium 14, plus the stroke of the lower plate 23 insert of the upper plate 13 to be determined to move downward relative to the lower plate 23; and the stroke of the lower plate 23 insert driven by the upper plate 13 to move downward relative to the lower plate 23 multiplied by the bottom area of ​​the lower plate 23 is equal to the volume of liquid medium 14 required for the hydroforming of the sheet metal workpiece 12. In the present application, the surface of the lower plate 23 is provided with a groove, and the horizontal cross-sectional area of ​​the groove is smaller than the horizontal cross-sectional area of ​​the lower plate 23, i.e., the lower support plate insert 21 cannot move downward further when it moves downward to the top of the lower plate 23. The present application can achieve hydroforming of different sheet metal workpiece 12 shapes by designing the height difference between the upper surface of the lower plate 23 and the lower support plate 22.

[0053] The control component controls the drive component to move the upper template 13 downward. The upper template 13 stops after moving down to the set position. The pressure sensor 24 monitors the pressure inside the hydraulic chamber. Usually, the pressure monitored at this time is equal to or slightly less than the pressure required for forming. The drive component drives the upper template 13 to continue to move downward to achieve fine-tuning of the upper template 13 until the pressure monitored by the pressure sensor 24 reaches the preset value and is maintained for a period of time to ensure the hydraulic forming of the sheet metal workpiece 12. It is worth noting that the pressure sensor 24 in this application monitors the pressure at the bottom of the liquid chamber, and the forming pressure refers to the pressure at the bottom of the liquid chamber. Since the forming pressure is relatively large, usually greater than 100Mpa, and the height of the liquid chamber is relatively small, the pressure difference between the bottom and the bottom of the liquid chamber is negligible relative to 100Mpa and can be ignored.

[0054] During this process, the internal volume of the hydraulic chamber becomes smaller, and the pressure of the hydraulic medium continues to increase, forcing the sheet metal workpiece 12 to continuously fit the sheet metal workpiece 12 and the hydraulic forming mold in the upper template 13. The liquid medium 14 and the sheet metal workpiece 12 are pressed upward into the hydraulic forming mold together, so that the sheet metal workpiece 12 is hydraulically formed.

[0055] After the sheet metal workpiece 12 is formed, the control component controls the driving component to drive the upper template 13 to start moving up and down. The lower support plate 22 and the lower support plate insert 21 are reset under the action of the nitrogen spring 25. The liquid medium 14 pressed into the sheet metal workpiece 12 and the hydraulic forming mold also flows back to the liquid chamber, and the sheet metal workpiece 12 is taken out, completing a hydraulic forming process.

[0056] The present application converts the lower template 23 of the stamping die into a "plunger" for extruding the liquid medium 14. The stamping pressure of ordinary stamping equipment is used to work on the lower template 23. The lower template 23 pressurizes the liquid medium 14 added to the liquid chamber in advance, converting the stamping pressure into liquid pressure, thereby forming the desired product shape; no additional hydraulic forming equipment and its filling and discharging process are required, thereby improving forming efficiency and reducing forming costs.

[0057] The hydraulic pressure in this invention can be adjusted continuously based on the position of the lower support plate 22 relative to the lower mold plate 23 during mold closing. The hydraulic pressure is monitored in real time by a pressure sensor 24. When the required hydraulic pressure is reached, the pressure sensor 24 transmits a signal to the control unit, shutting down the equipment. This prevents excessive pressure from causing product quality problems and protects the hydroforming mold.

[0058] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A sheet metal hydraulic forming device, characterized in that: include: an upper die, comprising an upper platen, wherein a hydroforming die containing a sheet metal workpiece is secured to the bottom of the upper platen; A lower mold, comprising a lower mold plate and a lower supporting plate located around the lower mold plate, wherein the lower mold plate and the lower supporting plate are slidably and sealedly connected, an upper surface of the lower supporting plate is higher than an upper surface of the lower mold plate, and the upper surface of the lower mold plate and an inner side wall of the lower supporting plate form a hydraulic chamber; When the upper and lower mold plates are closed, the upper mold plate drives the lower support plate to move downward relative to the lower mold plate, so that the liquid medium in the hydraulic chamber moves toward the surface of the sheet metal workpiece fixed to the bottom of the upper mold plate, forming hydraulic pressure; A groove is provided on the upper surface of the lower template, and the groove and the inner wall of the lower support plate form a hydraulic chamber; the lower mold also includes a lower support plate insert, which is fixed to the inner wall of the lower support plate, and the lower support plate insert is fixedly connected to the lower support plate, and the lower support plate insert is slidingly and sealedly connected to the lower template; a first seal is provided on the upper surface of the lower support plate insert, and when the upper template and the lower template are in a closed mold state, the first seal abuts against the upper template; a second seal is provided on the inner wall of the lower support plate insert.

2. A sheet metal hydraulic forming device according to claim 1, characterized in that: A compression spring is provided at the bottom of the lower supporting plate, the bottom end of the compression spring is fixed on the forming platform, and the top end is fixed on the bottom of the lower supporting plate.

3. The sheet metal hydraulic forming device according to claim 1, characterized in that: The outer edge of the lower supporting plate is provided with a guide column, and the upper template is provided with a socket adapted to the guide column.

4. The sheet metal hydraulic forming device according to claim 1, characterized in that: A pressure sensor is provided at the bottom of the hydraulic chamber.

5. The sheet metal hydraulic forming device according to claim 4, characterized in that: It also includes a control component and a drive component, wherein the drive component is fixedly connected to the upper template and can drive the upper template to move toward or away from the lower template; the control component is communicatively connected to the drive component and the pressure sensor; the control component calculates the volume of liquid medium required for the hydraulic forming of the sheet metal workpiece based on the target shape of the sheet metal workpiece, and controls the control component to drive the upper template to move downward to a corresponding stroke; the control component fine-tunes the stroke of the upper template based on the monitoring value of the pressure sensor.

6. A method for sheet metal hydroforming using the sheet metal hydroforming device according to any one of claims 1 to 5, characterized in that: include: A hydraulic forming die containing a sheet metal workpiece is fixed to the bottom of an upper die plate; a liquid medium is filled inside a hydraulic chamber; the upper die plate drives a lower support plate to move downward relative to the lower die plate, causing the liquid medium in the hydraulic chamber to move toward the surface of the sheet metal workpiece fixed to the bottom of the upper die plate, forming hydraulic pressure; and the sheet metal workpiece is forced to be hydraulically formed under the action of the hydraulic forming die and hydraulic pressure.

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