An electric-assisted forming process for a titanium alloy spherical tank

Abstract

The present invention discloses an electrically assisted forming process for a titanium alloy spherical tank, comprising the following steps: a slab is clamped on the top surface of an annular pressure plate substrate; a three-coordinate positioning mechanism drives the stamping assembly to be positioned layer by layer from the inside to the outside in accordance with a preset forming route, directly above the die assembly unit in each annular layer, and the stamping electrode plate and the back-pressure electrode plate located therebelow are both energized through an external power supply device; the stamping electrode plate moves downward, and the stamping electrode plate and the back-pressure electrode plate energize and heat the local area of ​​the slab located therebetween and load the stamping; the hemispherical structure is energized as a whole to complete stress relaxation; and each functional component is reset. The present invention adopts a local area micro-stamping and annular layer partition cumulative stamping forming process, combined with a short-time high-current energized auxiliary heating process, to improve the forming performance of the sheet while avoiding significant changes in the internal structure and surface of the material; the various functional components of the forming device are assembled in a detachable manner, which is convenient for local replacement when a local area is damaged.

Description

Technical Field

[0001] The invention relates to the technical field of metal stamping and forming, in particular to an electric-assisted forming process for a titanium alloy spherical tank. Background Art

[0002] At present, the commonly used methods for the production and manufacturing of titanium alloy spherical tanks mainly include traditional hot forming and spinning. The traditional hot forming process has the following shortcomings:

[0003] A. Since the size of the titanium alloy spherical tank is large, the size of the press required for overall manufacturing is also large, making the supporting equipment complex, large in number, and high in cost;

[0004] B. The most critical equipment for traditional hot forming is the heating furnace and the press. Large-sized spherical storage tanks are difficult to transport, and heat dissipation occurs during transportation. The large size means a large heat dissipation area. The heat dissipation temperature drops by up to 200°C within 1 minute, so the heating energy consumption is high. The 800°C high-temperature thin-walled sheet contacts the 20°C cold mold. The heat is transferred from the high-temperature object to the low-temperature object. The high-temperature thin-walled sheet cools quickly, the material fluidity is weak, and the forming quality is poor.

[0005] C. In order to minimize the forming temperature drop problem, the preheating temperature of thin-walled plates needs to be increased. However, the higher the temperature, the stronger the oxidation of titanium alloy. Long-term high-temperature environment causes titanium alloy to be oxidized, making the plate easy to crack during the forming process. Thin-walled plates have to experience a long-term high-temperature environment in the heating furnace. After heating to the preset temperature, they still need to be kept warm for a period of time. The internal structure and properties of the material change, which is quite different from the original structure. The low-quality parts are formed at the cost of changing the structure and properties;

[0006] D. Thin-walled sheets have obvious springback phenomenon during the stamping process, and subsequent heat treatment experiments are required to achieve the purpose of stress relaxation.

[0007] There are the following deficiencies in the spinning process:

[0008] A. First spin the large hemispherical surface, then spin the flanged spherical surface, and then perform a long-term heat treatment after spinning to eliminate residual stress, and finally perform precision machining. The process steps are complicated and still require large-scale supporting equipment and workshops;

[0009] B. Spin forming has high requirements on the thickness of raw materials, at least on the basis of a certain thickness. Because the thickness of spin forming decreases gradually, spin forming is difficult to achieve on ultra-thin plates (t = 1mm);

[0010] C. The sheet needs to be heated before spinning. Frictional heat will also occur during the spinning process, resulting in obvious oxidation color on the surface of the sheet and overburning in some areas.

[0011] D. The speed in the spinning process has been summarized through many experiments. It is concluded that if the speed is too low, the thickness of the plate will be reduced slightly, and if the speed is too fast, the thickness of the plate will be severely reduced and the surface will be oxidized and become brittle. Summary of the invention

[0012] In view of the above-mentioned defects and shortcomings, the present invention provides an electrically assisted forming device and process for a titanium alloy spherical tank. The device and process adopt a stamping process of local area micro-stamping forming and ring layer partition cumulative stamping forming, which are similar to the shot peening process and are different from the traditional hot forming process and the spinning forming process. The local area micro-stamping process is combined with a short-time high-current power-assisted heating process to improve the forming performance of the sheet while avoiding significant changes in the internal structure of the material and significant oxidation on the surface. The functional components of the forming device are assembled in a detachable manner to facilitate local replacement when a local area is damaged.

[0013] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0014] A titanium alloy spherical tank electric-assisted forming device comprises a supporting base plate, a plurality of base plate supporting columns fixedly arranged on the edge of the bottom surface of the supporting base plate, a plurality of pressure plate supporting columns fixedly arranged on the edge of the top surface of the supporting base plate, an annular pressure plate base plate fixedly arranged on the top of the pressure plate supporting columns, a clamping assembly fixedly arranged above the annular pressure plate base plate, and a three-coordinate positioning mechanism fixedly arranged above the annular pressure plate base plate and outputting vertically;

[0015] The support substrate is provided with a die assembly, the die assembly comprises a plurality of die ring assemblies which are coaxially adjacent to each other in sequence, and each die ring assembly is composed of a plurality of die assembly units which are adjacent to each other in sequence;

[0016] The die assembly unit comprises a back pressure cylinder vertically fixedly arranged on a supporting base plate, and a back pressure electrode plate fixedly connected to an output shaft end at the top of the back pressure cylinder. The back pressure electrode plates of each die assembly unit are commonly connected to an output electrode of an external power supply device and the back pressure electrode plates are insulated from each other. The top surfaces of all the back pressure electrode plates in the same die annular assembly form an annular plane, and the annular planes of all the die annular assemblies form a circular plane.

[0017] The output end of the three-coordinate positioning mechanism is fixedly provided with a vertically positionable stamping assembly, the stamping assembly includes a stamping cylinder, the bottom output end of the stamping cylinder is fixedly connected with a stamping electrode plate, and the stamping electrode plate is connected to another output electrode of an external power supply device;

[0018] The slab to be formed is fixed on the top surface of the annular pressure plate base by the clamping assembly, and the top surface of each back pressure electrode plate contacts the bottom surface of the slab. The three-coordinate positioning mechanism drives the stamping assembly to be located circumferentially and successively above each die assembly unit in each die annular assembly, and from the inside to the outside, it is located successively above each die annular assembly. The stamping cylinder drives the stamping electrode plate downward to apply stamping pressure to the top surface of the slab to cause local drawing and deformation of the slab. During the stamping process, the stamping electrode plate and the back pressure electrode plate located directly below it are energized at the same time.

[0019] Furthermore, the clamping assembly includes a cylinder bracket fixedly connected to the outer side of the top of the pressure plate support column, a slide rail fixedly connected to the top of the cylinder bracket and distributed radially along the annular pressure plate base plate, a push-pull cylinder fixedly installed on the outer end of the top surface of the slide rail, a slider slidably connected to the top of the slide rail, a mobile cylinder bracket fixedly connected to the output rod end of the push-pull cylinder and fixedly arranged on the top surface of the slider, at least one clamping cylinder fixedly installed on the top of the mobile cylinder bracket and a pressure plate fixedly connected to the output shaft end of the clamping cylinder and arranged parallel to the annular pressure plate base plate, and the pressure plates in each clamping assembly are spliced ​​to form a complete annular plate.

[0020] Furthermore, the die assembly unit also includes a first cylinder mounting bracket fixedly connected to the supporting base plate, a limit plate movably mounted on the outside of the first cylinder mounting bracket, and a plurality of studs fixedly connected to the top surface of the supporting base plate. The back pressure cylinder is fixedly mounted on the top of the first cylinder mounting bracket, and each of the studs is threadedly connected with an adjusting nut. The limit plate is mounted on the outside of the stud and is placed on the top surface of the adjusting nut.

[0021] Furthermore, the stamping assembly also includes a second cylinder mounting bracket fixedly connected to the output end of the three-coordinate positioning mechanism, the stamping cylinder is fixedly installed in the second cylinder mounting bracket, and at least one guide column is fixedly connected to both sides of the top surface of the stamping electrode plate, and the top of the guide column movably passes through the bottom of the second cylinder mounting bracket.

[0022] Furthermore, an insulating guide sleeve is fixedly provided on the outer side of the bottom of the back-pressure electrode plate, and the cross-sectional shape of the insulating guide sleeve matches the contour shape of the back-pressure electrode plate, and the vertical plane side walls of two adjacent insulating guide sleeves in the same die ring assembly are slidably fitted, and the vertical arc-shaped side walls of two adjacent insulating guide sleeves in two adjacent die ring assemblies are slidably fitted.

[0023] Furthermore, the top of the insulating guide sleeve is provided with an embedding groove matching the contour of the back pressure electrode plate, the back pressure electrode plate is embedded in the embedding groove, and the top surface of the back pressure electrode plate is located above the top surface of the insulating guide sleeve.

[0024] Furthermore, the annular pressure plate base plate is formed by splicing a plurality of arc-shaped plates, and a side panel with an arc-shaped cross-section is integrally provided on the inner side of each arc-shaped plate, and the side panel is slidably fitted with the outer vertical arc-shaped side wall of the insulating guide sleeve in the outermost die annular component.

[0025] Furthermore, an insulating connector is fixedly connected to the bottom surface of the back-pressure electrode plate, a wiring terminal is fixedly clamped between the insulating connector and the back-pressure electrode plate, and the output shaft end of the back-pressure cylinder is fixedly connected to the insulating connector.

[0026] Furthermore, a travel control switch is provided at the bottom end of the inner wall of the insulating guide sleeve.

[0027] A titanium alloy spherical tank electric-assisted forming process is also provided, which is applied to the titanium alloy spherical tank electric-assisted forming process, and comprises the following steps:

[0028] S1. Place the slab to be formed on the top surface of the annular platen substrate, and clamp and fix the edges of the slab by various clamping assemblies, each back pressure electrode plate contacts the bottom surface of the slab, and each back pressure cylinder provides back pressure to the bottom surface of the slab through the corresponding back pressure electrode plate;

[0029] S2, driving the stamping assembly to be positioned directly above one of the die assembly units of the innermost die ring assembly through the three-coordinate positioning mechanism, the stamping electrode plate on the stamping assembly and the back pressure electrode plate on the die assembly unit located below it are both powered by an external power supply device, and the electrical properties of the stamping electrode plate and the back pressure electrode plate are opposite;

[0030] S3, the stamping cylinder drives the stamping electrode plate downward, and after the stamping electrode plate contacts the top surface of the slab and the back pressure electrode plate contacts the bottom surface of the slab, the stamping electrode plate, the back pressure electrode plate and the local area of ​​the slab between the two electrode plates instantly form a closed current path, and a short-term high-current power-on mode is adopted to form a high-temperature environment in the local area where the slab contacts the two electrode plates. The difference between the stamping pressure provided by the stamping cylinder and the back pressure provided by the back pressure cylinder directly below it forms a downward local load on the heated local area of ​​the slab, so that the local area is concave by a preset vertical distance, completing the stamping forming of the local area, and the stamping cylinder drives the stamping electrode plate upward to reset;

[0031] S4, the three-coordinate positioning mechanism drives the stamping assembly to be positioned directly above the next die assembly unit in the same die ring assembly adjacent to the aforementioned die assembly unit, and performs the same process as step S3 to complete the stamping forming of the corresponding local area on the slab;

[0032] S5, repeating step S4 until each of the concave die assembly units in the same concave die annular assembly located on the inner side cooperates with the stamping electrode plate to complete the stamping forming of the corresponding local area;

[0033] S6, the three-coordinate positioning mechanism drives the stamping assembly to be positioned directly above one of the die assembly units in the outer die ring assembly adjacent to the inner die ring assembly, and executes steps S3 to S5 until all the die assembly units in each die ring assembly respectively cooperate with the stamping electrode plate to complete the stamping forming of the corresponding local area, and the blank after stamping forms a hemispherical structure with a concave middle portion and a stepped cross section;

[0034] S7, using the same process as step S6 to complete the stamping forming of the corresponding local areas of the remaining ring layers of the slab layer by layer;

[0035] S8. The three-coordinate positioning mechanism drives the stamping assembly to be positioned at the center of the top surface of the hemispherical structure. The stamping electrode plate on the stamping assembly and the back-pressure electrode plates on all the die assembly units are powered on through an external power supply device. The electrical properties of the stamping electrode plate and the back-pressure electrode plate are opposite. The stamping electrode plate, all the back-pressure electrode plates and the hemispherical structure form a closed current path, and the hemispherical structure is powered on as a whole to quickly heat up, thereby completing stress relaxation of the semi-formed part in a pressure-maintained state.

[0036] S9, the external power supply equipment stops working, the stamping cylinder drives the stamping electrode plate to reset upward, the clamping assembly resets, and all the back pressure cylinders simultaneously drive the corresponding back pressure electrode plates to rise, pushing the hemispherical structure upward.

[0037] Furthermore, in step S3, the preset concave distance of a single stamping forming is determined by setting the output current of the external power supply device, the difference between the stamping force and the back pressure, and the duration of the electrical contact.

[0038] Furthermore, in step S4, the vertical distances of the back pressure electrode plates of each die assembly unit in each die ring assembly moving downward in the same loading cycle are the same.

[0039] Furthermore, in step S6, the remaining back-pressure electrode plates on the inner side of the back-pressure electrode plate matched with the stamping electrode plate are in a non-contact state with the plate blank, that is, the corresponding back-pressure cylinders are in a contracted state.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] 1. The present invention realizes rapid heating of the plate blank by adopting the method of power-on auxiliary heating, which can avoid the plate blank being in a heated state for a long time, avoid grain coarsening and performance degradation of the internal structure of the material, thereby making the surface forming quality of the semi-formed part better and the modeling accuracy higher;

[0042] 2. The present invention adopts a local area micro-stamping process similar to the shot peening process, and a stamping process route of ring layer partition cumulative stamping. In the local area micro-stamping process, a short-time high-current power-on auxiliary heating process is combined to achieve centralized and rapid heating of the local forming area of ​​the slab, which can effectively improve the heating efficiency of the slab, and can avoid significant changes in the internal structure of the material and significant oxidation on the surface while improving the forming performance of the sheet, thereby improving the forming quality of the product. After stamping, the whole is electrically heated to achieve stress relaxation, the residual stress decreases quickly, and the springback is reduced, so that the surface accuracy of the formed part is high;

[0043] 3. The present invention combines a short-time high-current power-on auxiliary heating process in the local area micro-stamping forming process to achieve centralized and rapid heating of the local forming area of ​​the slab without the need to transfer the slab. Different from the traditional hot forming process and the spinning forming process, the temperature drop problem during the transfer process can be avoided, the heat energy loss can be reduced, and the production cost can be reduced;

[0044] 4. All functional components of the forming device of the present invention are detachably assembled, which is convenient for local replacement when a local area is damaged. The assembly and disassembly operations of the device are relatively easy, thereby reducing the production, maintenance, transfer and other use costs of the mold;

[0045] 5. The present invention pre-sets the vertical stamping cumulative depth of the back-pressure electrode plates of each ring layer, so that the plate blank can eventually form a hemispherical shell structure with different elliptical cross-sections in the vertical direction, which is convenient for the stamping forming of hemispherical shell structures of different specifications; by setting the number of layers of the die ring component, the radius size of the stamping area can be adjusted to meet the stamping forming of hemispherical shell structures with different horizontal radius sizes, and has flexible applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is one of the three-dimensional structural schematic diagrams of the titanium alloy spherical tank electric-assisted forming device of the present invention;

[0047] Figure 2 This is the second schematic diagram of the three-dimensional structure of the electric-assisted forming device for a titanium alloy spherical tank of the present invention;

[0048] Figure 3 is a schematic diagram of the three-dimensional structure of the three-coordinate positioning mechanism;

[0049] Figure 4 It is a schematic diagram of the three-dimensional structure of the stamping component;

[0050] Figure 5 is a schematic diagram of the three-dimensional structure of the annular pressure plate substrate;

[0051] Figure 6It is a three-dimensional structural schematic diagram of the annular pressure plate base plate, the clamping assembly and the concave mold assembly in an assembled state;

[0052] Figure 7 is one of the three-dimensional structural schematic diagrams of the clamping assembly;

[0053] Figure 8 The second is a schematic diagram of the three-dimensional structure of the clamping assembly;

[0054] Fig. 9 It is a three-dimensional structural schematic diagram of the slab being clamped;

[0055] Fig.10 It is one of the three-dimensional structural schematic diagrams of the assembly state of the back pressure electric clamping plate and the insulating guide sleeve;

[0056] Fig.11 The second is a three-dimensional structural schematic diagram of the assembled state of the back pressure electric clamping plate and the insulating guide sleeve;

[0057] Fig.12 is a schematic diagram of the three-dimensional structure of the concave mold assembly unit;

[0058] Fig.13 is a three-dimensional structural schematic diagram of the back pressure electrode plate assembly state;

[0059] Fig.14 A schematic diagram of the punching route of the punching electrode plate;

[0060] Fig.15 The present invention is a flow chart of the electric-assisted forming process of the titanium alloy spherical tank.

[0061] In the figure: 1, support base plate; 2, base plate support column; 3, pressure plate support column; 4, annular pressure plate base plate; 401, side panel; 5, three-coordinate positioning mechanism; 501, base; 502, horizontal transverse linear module; 503, horizontal longitudinal linear module; 504, positioning frame plate; 505, vertical linear module; 6, clamping assembly; 601, cylinder bracket; 602, clamping cylinder; 603, pressure plate; 604, slide rail; 605, push-pull cylinder; 606, movable cylinder bracket; 607, slider; 7, die assembly unit; 701, back pressure cylinder; 702, back pressure electrode plate; 703, first cylinder mounting frame; 704, limit plate; 705, stud; 706, insulating guide sleeve; 7061, through port; 707, insulating connector; 8, stamping assembly; 801, stamping cylinder; 802, stamping electrode plate; 803, guide column; 804, second cylinder mounting frame; 10, slab. DETAILED DESCRIPTION

[0062] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0063] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may be a central component at the same time.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0065] The present invention provides an electric-assisted forming device for a titanium alloy spherical tank, comprising a supporting base plate 1, a plurality of base plate supporting columns 2 fixedly arranged on the bottom edge of the supporting base plate 1, a plurality of pressure plate supporting columns 3 fixedly arranged on the top edge of the supporting base plate 1, an annular pressure plate base plate 4 fixedly arranged on the top of the pressure plate supporting columns 3, a clamping assembly 6 fixedly arranged above the annular pressure plate base plate 4, a three-coordinate positioning mechanism 5 fixedly arranged above the annular pressure plate base plate 4 and outputting vertically, and a vertically positionable stamping assembly 8 fixedly arranged at the output end of the three-coordinate positioning mechanism 5. A die assembly is arranged on the supporting base plate 1, and the die assembly comprises a plurality of die annular assemblies coaxially adjacently sleeved in sequence, and each die annular assembly is composed of a plurality of die assembly units 7 adjacently spliced ​​in sequence.

[0066] Since the forming object used by the electric-assisted forming device is relatively large, the volume and weight of the corresponding functional components are relatively large. If each functional component adopts an integral structure, there will be problems of inconvenience in transfer and assembly. In addition, due to the high requirements on the forming quality of the formed part, once the functional component (especially the forming part) is partially damaged, the corresponding functional component needs to be replaced as a whole. There are still problems of time-consuming and labor-intensive disassembly and assembly. At the same time, the integral structure also has problems of difficult processing and high cost of use. Based on the above problems, each functional component of the present invention adopts a detachable assembly structure, which is convenient for the assembly and disassembly of each functional component, especially a certain assembly unit in the functional component can be directly replaced in situ when damaged, and it is convenient for storage and transfer after overall disassembly, which effectively reduces the maintenance and use costs.

[0067] The specific structure and use process of each functional component of the present invention are described in detail below.

[0068] Since the object formed by the forming device is a hemispherical shell structure with a flanged edge, the supporting base plate 1 is a circular plate formed by sequentially splicing a plurality of fan-shaped plates, and the main bodies of the base plate supporting column 2 and the pressure plate supporting column 3 are both made of steel sections, with connecting flanges welded at both ends of the main bodies, the base plate supporting columns 2 are evenly distributed on the circumference of the bottom edge of the supporting base plate 1 and are fixed by bolts, and the bottom ends of the base plate supporting columns 2 are fixed to the foundation of the work site by bolts, and the pressure plate supporting columns 3 are correspondingly arranged directly above the base plate supporting columns 2 and are fixed to the supporting base plate 1 by bolts, forming the overall supporting frame of the equipment, and facilitating the disassembly, transportation and assembly of the equipment.

[0069] In order to facilitate assembly and disassembly and save costs, the three-coordinate positioning structure 5 is constructed using a ball screw linear module driven by a servo motor, and is used in conjunction with an existing motion controller to achieve motion control in the three-coordinate directions. Figure 3 As shown, the three-coordinate positioning structure 5 includes a base 501, a horizontal transverse linear module 502 fixedly arranged on both sides of the top surface of the base 501 and arranged in parallel, a horizontal longitudinal linear module 503 fixedly arranged on the top surface of the power output end of the horizontal transverse linear module 502, a positioning frame plate 504 fixedly arranged on the top surface of the power output end of the horizontal longitudinal linear module 503, and a vertical linear module 505 fixedly connected to the side of the positioning frame plate 504. Among them, the base 501 is a frame structure welded by square steel, and is fixedly connected to the foundation of the work site through a bracket (not shown in the figure), or fixedly connected to the outside of the base support column 2. The two horizontal transverse linear modules 502 move synchronously, driving the horizontal longitudinal linear module 503 to move horizontally (in the X-axis direction as shown in the figure). The horizontal longitudinal linear module 503 is arranged perpendicularly to the horizontal transverse linear module 502, driving the positioning frame plate 504 and the vertical linear module 505 to move horizontally and longitudinally (in the Y-axis direction as shown in the figure). The vertical linear module 505 is arranged vertically, driving the stamping assembly 8 to move vertically up and down. The stroke range of each linear module is determined according to the radius and diameter of the hemispherical shell-shaped parts to be processed, so that the horizontal transverse linear module 502 and the horizontal longitudinal linear module 503 can drive the vertical linear module 505 to be positioned in any processing area above the top surface of the plate blank 10, and the vertical linear module 505 can drive the stamping electrode plate 802 of the stamping assembly 8 to be positioned at any position within the range from the top surface of the plate blank 10 to the lowest point of the concave top surface of the hemispherical shell to meet the processing requirements.

[0070] like Figure 3 and Figure 4As shown, the stamping assembly 8 includes a stamping cylinder 801, and the bottom output end of the stamping cylinder 801 is fixedly connected to a stamping electrode plate 802, and the stamping electrode plate 802 is connected to another output electrode of an external power supply device. The stamping assembly 8 also includes a second cylinder mounting frame 804 fixedly connected to the output end of the three-coordinate positioning mechanism 5, the stamping cylinder 801 is fixedly installed in the second cylinder mounting frame 804, and at least one guide column 803 is fixedly connected to both sides of the top surface of the stamping electrode plate 802, and the top of the guide column 803 is movable through the bottom of the second cylinder mounting frame 804. Specifically, the second cylinder mounting frame 804 is vertically arranged, and its top end is fixedly connected to the power output end of the vertical linear module 505, and the stamping cylinder 801 is fixedly installed at the bottom end of the second cylinder mounting frame 804, and its output shaft is vertically arranged downward. The vertical linear module 505 drives the stamping cylinder 801 and the stamping electrode plate 802 to move vertically to achieve vertical positioning. The stamping cylinder 801 drives the stamping electrode plate 802 to move downward to cooperate with the back pressure electrode plate 702 directly below it to provide energized electrodes for the upper and lower ends of the sheet blank 10, and at the same time cooperate with the back pressure electrode plate 702 directly below it to provide a pressure difference between the upper and lower surfaces of the sheet blank 10, thereby applying forming pressure to the corresponding area of ​​the sheet blank 10. The guide column 803 plays a guiding role in the vertical movement of the stamping electrode plate 802.

[0071] like Figure 5 As shown, the annular pressure plate base plate 4 is composed of several arc-shaped plates spliced ​​together to form a complete circular ring plate, and is fixedly connected to the top surface of the pressure plate support column 3 by bolts to support the slab 10. During the forming process, the portion of the slab 10 located on the inner side of the annular pressure plate base plate 4 is recessed downward to form a hemispherical shell structure, and the portion located on the top surface of the annular pressure plate base plate 4 forms a flange at its top edge. A side panel 401 with an arc-shaped cross-section is integrally provided on the inner side of each arc-shaped plate, and each side panel 401 is spliced ​​in sequence to form a cylindrical structure. The side panel 401 slides and fits with the outer vertical arc-shaped side wall of the insulating guide sleeve 706 in the outermost die ring assembly, thereby forming an outer encirclement for the inner die assembly and guiding the vertical movement of the outer insulating guide sleeve 706, as shown in FIG. Figure 6 shown.

[0072] like Figure 7 and Figure 8As shown, the clamping assembly 6 includes a cylinder bracket 601 fixedly connected to the outer side of the top of the pressure plate support column 3, a slide rail 604 fixedly connected to the top of the cylinder bracket 601 and distributed radially along the annular pressure plate base plate 4, a push-pull cylinder 605 fixedly installed on the outer end of the top surface of the slide rail 604, a slider 607 slidably connected to the top of the slide rail 604, a mobile cylinder bracket 606 fixedly connected to the output rod end of the push-pull cylinder 5 and fixedly arranged on the top surface of the slider 607, at least one clamping cylinder 602 fixedly installed on the top of the mobile cylinder bracket 606 and a pressure plate 603 fixedly connected to the output shaft end of the clamping cylinder 602 and arranged parallel to the top of the annular pressure plate base plate 4, and the pressure plates 603 in each clamping assembly 6 are spliced ​​to form a complete annular plate. Before forming, the output shafts of each push-pull cylinder 605 are in a retracted state. At this time, each pressing plate 603 is dispersed and located on the outside above the top surface of the annular pressing plate substrate 4, so that the circular slab 10 can be placed vertically underground above the annular pressing plate substrate 4. After adjusting the clamping position of the slab 10, each push-pull cylinder 605 pushes each movable cylinder bracket 606 and the clamping cylinder 602 and pressing plate 603 thereon to gather inward, so that each pressing plate 603 is located directly above the annular pressing plate substrate 4 and spliced ​​together to form a complete annular plate, and then each clamping cylinder 602 drives each pressing plate 603 to move downward at the same time, and the bottom surface of the pressing plate 603 contacts the top surface of the slab 10 and applies a clamping force, so that the slab 10 is fixedly clamped on the annular pressing plate substrate 4, as shown in FIG. Fig. 9 shown.

[0073] like Figures 10 to 12 As shown, the die assembly unit 7 includes a back pressure cylinder 701 vertically fixedly arranged on the supporting substrate 1, and a back pressure electrode plate 702 fixedly connected to the top output shaft end of the back pressure cylinder 701, the back pressure electrode plate 702 of each die assembly unit 7 is commonly connected to an output electrode of an external power supply device and each back pressure electrode plate 702 is insulated from each other, the top surfaces of all the back pressure electrode plates 702 in the same die annular assembly constitute an annular plane, and each annular plane of all the die annular assemblies constitutes a circular plane, which corresponds to the entire recessed forming area of ​​the slab 10. During the forming process, one of the back pressure electrode plates 702 located directly below the stamping electrode plate 802 is in an energized state, and cooperates with the energized stamping electrode plate 802, adopting a short-time high current energization mode, forming a high temperature environment in the local area where the slab 10 contacts the two electrode plates, and the difference between the stamping pressure provided by the stamping cylinder 801 and the back pressure provided by the back pressure cylinder 701 directly below it forms a downward local load on the heated local area of ​​the slab 10, so that the local area is concave by a preset vertical distance, completing a single stamping forming of the local area. The preset concave distance of the single stamping forming is determined by setting the output current of the external power supply device, the difference between the stamping pressure and the back pressure, and the duration of the energized contact.

[0074] like Fig.10 and Fig.11 As shown, an insulating guide sleeve 706 is fixedly arranged on the outer side of the bottom of the back pressure electrode plate 702, and the cross-sectional shape of the insulating guide sleeve 706 matches the contour shape of the back pressure electrode plate 702, and the vertical plane side walls of two adjacent insulating guide sleeves 706 in the same die ring assembly slide in contact with each other, and the vertical arc-shaped side walls of two adjacent insulating guide sleeves 706 in two adjacent die ring assemblies slide in contact with each other, as shown in FIG. Fig.13 As shown. The insulating guide sleeve 706 is made of hard insulating material, and a groove matching the contour of the back pressure electrode plate 702 is opened on the top thereof. The back pressure electrode plate 702 is embedded in the groove, and the top surface of the back pressure electrode plate 702 is located above the top surface of the insulating guide sleeve 706. In this way, the insulation between the back pressure electrode plates 702 is achieved through each insulating guide sleeve 706, and the vertical movement of the back pressure electrode plates 702 is guided by the sliding fit between each other. Since the blank 10 after stamping forms a hemispherical structure with a concave middle part and a stepped cross-section, the total vertical downward movement distance of the back-pressure electrode plate 702 in the inner die ring assembly is greater than the total vertical downward movement distance of the back-pressure electrode plate 702 in the adjacent outer die ring assembly. Therefore, the vertical height of the insulating guide sleeve 706 on the outside must be no less than the difference in the total vertical downward movement distance, so that the vertical arc-shaped side walls of the insulating guide sleeves 706 of the inner and outer rings are always in contact, and the vertical height of any insulating guide sleeve 706 is no less than the total vertical downward movement height of the back-pressure electrode plate 702 thereon, so that the vertical plane side walls of each insulating guide sleeve 706 located in the same die ring assembly are always in contact, ensuring that they are mutually positionally restricted and vertically guided.

[0075] The bottom surface of the back pressure electrode plate 702 is fixedly connected with an insulating connector 707, and a wiring terminal is fixedly clamped between the insulating connector 707 and the back pressure electrode plate 702, which is used to connect with the output electrode of the external power supply device through a wire, and the output shaft end of the back pressure cylinder 701 is fixedly connected to the insulating connector 707. A through hole 7061 is opened at the top of the vertical plane side wall of the insulating guide sleeve 706 to facilitate the loading and unloading operation of the insulating connector 707 on the output shaft end of the back pressure cylinder 701.

[0076] The die assembly unit 7 also includes a first cylinder mounting frame 703 fixedly connected to the support base plate 1, a limit plate 704 movably sleeved on the outside of the first cylinder mounting frame 703, and a plurality of studs 705 fixedly connected to the top surface of the support base plate 1. The back pressure cylinder 701 is fixedly mounted on the top of the first cylinder mounting frame 703, and each stud 705 is threadedly connected with an adjusting nut (not shown in the figure). The limit plate 704 is sleeved on the outside of the stud 705 and is placed on the top surface of the adjusting nut. The vertical positioning of the back pressure cylinder 701 is achieved through the first cylinder mounting frame 703. By adjusting the vertical position of the adjusting nut on the stud 705, the vertical height of the limit plate 704 can be adjusted, so that when the output rod of the back pressure cylinder 701 is fully extended, the distance between the highest position of the bottom surface of the corresponding insulating guide sleeve 706 and the top surface of the limit plate 704 is the total vertical downward movement distance of the corresponding back pressure electrode plate 702. In this way, when the back pressure electrode plate 702 cooperates with the stamping electrode plate 802 to complete the local stamping of the slab 10 to the preset cumulative depth (the total vertical downward movement distance of the back pressure electrode plate 702), the bottom surface of the insulating guide sleeve 706 contacts the top surface of the corresponding limit plate 704 and stops moving downward, and the stamping electrode plate 802 no longer performs subsequent stamping on this area. Preferably, a stroke control switch is provided at the bottom end of the inner wall of each insulating guide sleeve 706. The stroke control switch can be any one of a Hall proximity switch, a pressure sensor, and a mechanical switch. Each stroke control switch is connected to the control system of the device. When the stroke control switch is triggered, it indicates that the local area corresponding to the slab 10 has been formed to the preset depth, and the three-coordinate positioning mechanism 5 will no longer drive the stamping assembly 8 to be positioned directly above the local area.

[0077] By adjusting the vertical height of the limit plate 704 of each ring layer, the vertical stamping cumulative depth of the back pressure electrode plate 702 of each ring layer can be set, so that the plate blank 10 will eventually form a hemispherical shell structure with different elliptical cross-sections in the vertical direction, which is convenient for the stamping forming of hemispherical shell structures of different specifications; by setting the number of layers of the die ring component, the radius size of the stamping area can be adjusted to meet the stamping forming of hemispherical shell structures with different horizontal radius sizes.

[0078] See also Fig.15 , also provides a titanium alloy spherical tank electric-assisted forming process, which is applied to the titanium alloy spherical tank electric-assisted forming device, comprising the following steps:

[0079] S1. Place the slab 10 to be formed on the top surface of the annular platen substrate 4, and clamp and fix the edges of the slab 10 through the clamping assemblies 6. Each back pressure electrode plate 702 contacts the bottom surface of the slab 10, and each back pressure cylinder 701 provides back pressure to the bottom surface of the slab 10 through the corresponding back pressure electrode plate 702;

[0080] Before placing the slab 10, the output shaft of the back pressure cylinder 701 in each die assembly unit 7 is in a fully extended state, each back pressure electrode plate 702 and the corresponding insulating guide sleeve 706 are in the highest position, the stamping electrode plate 802 is connected to the positive output terminal of the external power supply device through a wire, and each back pressure electrode plate 702 is respectively connected to the negative output terminal of the external power supply device through a wire, and a relay is arranged in the connection line to control the power on or off of each back pressure electrode plate 702.

[0081] The downward movement height of the back-pressure electrode plate 702 of the die assembly unit 7 in each ring is calculated according to the radial width of the die assembly unit 7 in each ring and the number of ring layers of the die ring assembly. The vertical height of the limit plate 704 in each ring layer is adjusted by adjusting the nut, so that the distance between the top surface of the limit plate 704 in each ring layer and the bottom surface of the insulating guide sleeve 706 is equal to the total height that the back-pressure electrode plate 702 in the corresponding ring layer needs to move downward.

[0082] After placing the slab 10, the position of the slab 10 on the annular pressure plate base plate 4 is adjusted, and each push-pull cylinder 605 pushes each movable cylinder bracket 606 and the clamping cylinder 602 and the pressure plate 603 thereon to gather inward, so that each pressure plate 603 is located directly above the annular pressure plate base plate 4 and is spliced ​​together to form a complete annular plate, and then each clamping cylinder 602 simultaneously drives each pressure plate 603 to move downward, and the bottom surface of the pressure plate 603 contacts the top surface of the slab 10 and applies a clamping force, so that the slab 10 is fixedly clamped on the annular pressure plate base plate 4.

[0083] like Fig.14 As shown, the die ring assembly is divided into five ring layers A, B, C, D, and E from the inside to the outside as an example to specifically explain the stamping process of each local area of ​​the slab 10. In the figure, a, b, c, d, and e correspond to the total number of die assembly units 7 in the A, B, C, D, and E ring layers, respectively, and Aa represents the number of the a-th die assembly unit 7 in the A-th ring layer.

[0084] S2. Drive the stamping assembly 8 through the three-coordinate positioning mechanism 5 to be positioned directly above one of the die assembly units 7 of the innermost die ring assembly, for example, directly above numbered A1. The stamping electrode plate 802 on the stamping assembly 8 and the back-pressure electrode plate 702 on the die assembly unit 7 (numbered A1) located below it are both powered by an external power supply device, and the electrical connections between the stamping electrode plate 802 and the back-pressure electrode plate 702 are opposite.

[0085] S3, the stamping cylinder 801 drives the stamping electrode plate 802 downward, and after the stamping electrode plate 802 contacts the top surface of the sheet blank 10 and the back pressure electrode plate 702 contacts the bottom surface of the sheet blank 10, the stamping electrode plate 802, the back pressure electrode plate 702 and the local area of ​​the sheet blank 10 located between the two electrode plates instantly form a closed current path, and a short-term high-current power-on mode is adopted to form a high-temperature environment in the local area where the sheet blank 10 contacts the two electrode plates. The difference between the stamping pressure provided by the stamping cylinder 801 and the back pressure provided by the back pressure cylinder 701 directly below it forms a downward local load on the heated local area of ​​the sheet blank 10, so that the local area is concave by a preset vertical distance, completing a single stamping forming of the local area, and the stamping cylinder 801 drives the stamping electrode plate 802 upward to reset. The preset concave distance of a single stamping forming is determined by setting the output current of the external power supply device, the difference between the stamping pressure and the back pressure, and the duration of the power-on contact.

[0086] S4. The three-coordinate positioning mechanism 5 drives the stamping assembly 8 to be positioned directly above the next die assembly unit 7 (numbered A2) in the same die ring assembly adjacent to the aforementioned die assembly unit 7, and executes the same process as step S3 to complete the stamping of the corresponding local area on the slab 10.

[0087] In this process, since the preset concave vertical distance of a single stamping is small, the local areas of the slab 10 corresponding to two adjacent die assembly units 7 in the same ring layer are still in the same horizontal plane after a single stamping, that is, the back pressure electrode plates 702 of each die assembly unit 7 in each die annular assembly move downward the same vertical distance in the same loading cycle.

[0088] S5, repeating step S4 until each of the die assembly units 7 in the same die ring assembly located on the inner side cooperates with the stamping electrode plate 802 to complete a single stamping forming of the corresponding local area.

[0089] like Fig.14 As shown in the figure, the stamping electrode plates 802 cooperate with the back pressure electrode plates 702 in the concave die assembly units 7 numbered A1, A2, A3, ... Aa one by one in the counterclockwise direction to complete the stamping of the innermost local position of the plate blank 10 corresponding to the innermost A ring layer. After the stamping is completed, the corresponding area of ​​the plate blank 10 forms a circular plate that is concave (the preset single concave vertical distance is small).

[0090] S6, the three-coordinate positioning mechanism 5 drives the stamping assembly 8 to be positioned directly above one of the die assembly units 7 in the outer die ring assembly adjacent to the aforementioned inner die ring assembly, for example, directly above B1, and executes steps S3 to S5 until all the die assembly units 7 in each die ring assembly respectively cooperate with the stamping electrode plate 802 to complete the stamping forming of the corresponding local area, and the plate blank 10 after stamping forms a hemispherical structure with a concave middle and a stepped cross-section. In the process of the stamping electrode plate 802 respectively cooperating with the back pressure electrode plate 702 of each die assembly unit 7 in the B ring layer to complete the stamping forming, the output shaft of the back pressure cylinder 701 in each die assembly unit 7 corresponding to the A ring layer is in a contracted state, that is, the inner area of ​​the plate blank 10 that has completed a single stamping forming is in a free suspension state.

[0091] S7, using the same process as step S6 to complete the stamping forming of the corresponding local areas of the remaining ring layers of the slab layer by layer.

[0092] like Fig.14 As shown in , the stamping electrode plate 802 cooperates with the back pressure electrode plates 702 in the die assembly units 7 numbered B1, B2, B3...Bb one by one in the counterclockwise direction to complete the stamping forming of the annular local position of the slab 10 corresponding to the B ring layer. After the stamping forming of the corresponding area of ​​the slab 10 is completed, the local area forms an annular plate that is concave by a preset concave vertical distance, and the previously formed circular plates are cumulatively moved down by a preset concave vertical distance. By analogy, the stamping electrode plate 802 cooperates with the back pressure electrode plates 702 in the die assembly units 7 numbered C1, C2, C3...Cc one by one in the counterclockwise direction to complete the stamping forming of the annular local position of the slab 10 corresponding to the C ring layer. After the corresponding area of ​​the sheet blank 10 is stamped, the local area forms an annular plate that is concave by a preset vertical distance, and the previously formed annular plates are cumulatively moved down by a preset vertical distance, and the first formed circular plates are cumulatively moved down by a preset vertical distance. Until the stamping electrode plate 802 cooperates with the back pressure electrode plate 702 in each die assembly unit 7 in the E ring layer, after the stamping of the outermost side of the sheet blank 10 is completed, the outermost annular plate is concave by a preset vertical distance, and the innermost circular plate is cumulatively concave by a total of 5 preset vertical distances, so that the sheet blank 10 is formed from a plane into a conical surface with a concave middle (the cross section is a continuous stepped surface).

[0093] Control all the back pressure cylinders 701 of a certain ring layer and its outer side to drive all the back pressure electrode plates 702 to rise to contact with the bottom surface of the arc surface, and repeat the subsequent multiple stamping and forming of the ring plate corresponding to the ring layer. The total concave distance of the corresponding ring layer can be controlled, so that the conical surface gradually tends to the arc surface, until the bottom surface of the insulating guide sleeve 706 of each ring layer contacts the top surface of the corresponding limit plate 704 and triggers the corresponding stroke control switch. The control system of the equipment controls the three-coordinate positioning mechanism 5 to no longer drive the stamping assembly 8 to be positioned directly above the local area of ​​the plate blank 10 corresponding to the ring layer, and the stamping electrode plate 802 will no longer perform subsequent stamping and forming on this area. After all the stroke control switches are triggered, it means that the hemispherical shell structure has been stamped and formed.

[0094] S8. The three-coordinate positioning mechanism 5 drives the stamping assembly 8 to be positioned above the center of the top surface of the hemispherical structure. The stamping electrode plate 802 on the stamping assembly 8 and the back-pressure electrode plates 702 on all the die assembly units 7 are powered by an external power supply device. The electrical properties of the stamping electrode plate 802 and the back-pressure electrode plate 702 are opposite. The stamping electrode plate 802, all the back-pressure electrode plates 702 and the hemispherical structure form a closed current path, and the hemispherical structure is powered on as a whole to quickly heat up, thereby completing stress relaxation of the semi-formed part while maintaining pressure.

[0095] S9, the external power supply equipment stops working, the stamping cylinder 801 drives the stamping electrode plate 802 to reset upward, the clamping assembly 6 resets, and all the back pressure cylinders 701 simultaneously drive the corresponding back pressure electrode plates 702 to rise, pushing the hemispherical structure upward.

[0096] The hemispherical shell structure after electrically assisted forming can be transferred to the shaping equipment. In a manner similar to step S7, a short-term high current is respectively passed through the upper and lower surfaces of the hemispherical shell structure through the shaping punch and the shaping die to quickly heat the hemispherical shell structure as a whole, and the upper and lower surfaces of the hemispherical shell structure are smoothly shaped through the extrusion force between the shaping punch and the shaping die, and the remaining material of the top flange of the hemispherical shell structure is cut and polished to finally form a hemispherical shell.

[0097] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A titanium alloy spherical tank electric-assisted forming process, applied to a titanium alloy spherical tank electric-assisted forming device, the die assembly of the titanium alloy spherical tank electric-assisted forming device comprises a plurality of die ring assemblies which are coaxially adjacent to each other in sequence, the top surfaces of all back pressure electrode plates in the same die ring assembly form a ring-shaped plane, and the respective ring-shaped planes of all the die ring assemblies form a circular plane, which corresponds to the entire concave forming area of ​​the slab, and is characterized in that: the electric-assisted forming process comprises the following steps: S1, the clamping assembly fixes and clamps the slab to be formed on the annular pressing plate base plate, and the back pressure electrode plate contacts the bottom surface of the slab and provides back pressure to the bottom surface of the slab; S2, the stamping electrode plate is positioned directly above one of the back-pressure electrode plates of the innermost ring layer, and both the stamping electrode plate and the back-pressure electrode plate located below it are powered by an external power supply device, and the electrical properties of the two are opposite; S3, the stamping electrode plate moves downward and contacts the top surface of the slab, cooperates with the back pressure electrode plate below, and instantly passes a short-term high current into a local area of ​​the slab to quickly heat the local area. The downward local load causes the local area to be concave by a preset vertical distance, and then the stamping electrode plate moves upward to reset; S4, the stamping electrode plate is positioned directly above the next stamping electrode plate in the same ring layer adjacent to the aforementioned back pressure electrode plate, and the same process as step S3 is performed to complete the stamping forming of the corresponding local area on the plate blank, and each back pressure electrode plate in the same ring layer moves downward by the same vertical distance in the same loading cycle; S5, repeating step S4 until each back pressure electrode plate in the innermost ring layer cooperates with the stamping electrode plate to complete the stamping forming of the corresponding local area; S6, the stamped electrode plate is positioned directly above one of the back-pressure electrodes in the outer ring layer adjacent to the innermost ring layer, and steps S3 to S5 are executed until each back-pressure electrode plate in the outer ring layer cooperates with the stamped electrode plate to complete the stamping forming of the corresponding local area, and the plate blank after stamping forms a hemispherical structure with a concave middle and a stepped cross-section; each back-pressure electrode plate is insulated from each other, and the remaining back-pressure electrode plates on the inner side of the back-pressure electrode plate that cooperates with the stamped electrode plate are in a non-contact state with the plate blank; S7, using the same process as step S6 to complete the stamping forming of the corresponding local areas of the remaining ring layers of the slab layer by layer; S8. The stamping electrode plate is positioned at the center of the top surface of the hemispherical structure. The stamping electrode plate and all the back-pressure electrode plates are powered by an external power supply device, and the electrical properties of the two are opposite. The hemispherical structure is powered on as a whole to quickly heat up and complete stress relaxation in a pressure-maintained state. S9, the external power supply equipment stops working, the stamping electrode plate resets upward, the clamping assembly resets, all the back pressure electrode plates rise, and the hemispherical structure is pushed upward.

2. The electric-assisted forming process of a titanium alloy spherical tank according to claim 1 is characterized in that: In step S3, the preset concave distance of a single stamping forming is determined by setting the output current of the external power supply device, the difference between the stamping force and the back pressure, and the duration of the electrical contact.

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