High-temperature forming vacuum jacket for forming metal sheet and sheet forming method

Abstract

The present invention belongs to the technical field of sheet metal vacuum thermoforming, and particularly relates to a high-temperature forming vacuum envelope for forming metal sheets and a sheet forming method, including: a high-temperature forming vacuum envelope for forming metal sheets, including: an inner soft vacuum envelope with a cavity for accommodating a forming blank inside, and the cavity is in a vacuum environment; a hard envelope, which is wrapped outside the inner soft vacuum envelope. And a sheet forming method, including the following steps: S1. Place the forming blank in the cavity of the inner soft vacuum envelope, evacuate the cavity and then seal it; S2. Place the inner soft vacuum envelope containing the forming blank in the hard envelope; S3. Place the hard envelope in a hot press for processing; S4. After cooling, separate the formed component from the inner soft vacuum envelope and the hard envelope to obtain a formed metal part. The present invention can reduce the pumping cost, improve the pumping quality, and reduce the cost of vacuum hot pressing of the blank.

Description

Technical Field

[0001] The present invention belongs to the technical field of sheet metal vacuum thermoforming, and particularly relates to a high-temperature forming vacuum envelope for forming metal sheets and a sheet forming method. Background Art

[0002] Vacuum forming, with its special properties and wide application fields, has become an important force driving industrial progress. With the rapid development of the aviation industry, the demand for high-temperature vacuum formed parts of large-size and small-batch metal sheets is increasing. How to construct a high-temperature vacuum forming environment for large-size metal sheets at low cost and high quality has become a key issue in the aviation industry.

[0003] During the forming process of large-size metal sheets, to reduce the springback of the sheets, there needs to be a stress relaxation stage after sheet forming to improve the forming accuracy, and it is necessary to keep the metal sheets warm during this stage. Since the time required for heat preservation is relatively long, the oxidation of the sheets is serious. To improve the quality of metal sheets and reduce the oxidation degree during heat preservation, it is necessary to move the metal sheets to a vacuum environment for forming and heat preservation.

[0004] Common vacuum forming methods in industry include vacuum hot pressing furnaces and welded metal envelopes. A vacuum hot pressing furnace mainly consists of a furnace body, a furnace door, a heating, heat preservation and temperature measurement system, a vacuum system, an inflation system, a water cooling system, a control system, a hydraulic system, etc. It can effectively ensure the vacuum environment during high-temperature forming. However, due to the scarcity of large-size vacuum hot pressing furnace equipment, it is difficult to call the equipment and the furnace opening cost is relatively high, which greatly limits the vacuum forming of large-size metal sheets.

[0005] Although welded metal envelopes can effectively reduce the cost of vacuum forming, it is difficult to weld large-size envelopes and they are prone to air leakage. At the same time, the forming shape is limited and the deformation is too large, and weld cracking and air leakage are likely to occur, so it is impossible to effectively ensure the stability of the vacuum environment. Generally, it is commonly used for the heat preservation of materials with low vacuum degree requirements.

[0006] In summary, how to provide a large-size metal sheet forming device with good vacuum environment stability and low cost has become an urgent problem to be solved. Therefore, we propose a high-temperature forming vacuum envelope for forming metal sheets and a sheet forming method to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-temperature forming vacuum envelope for forming metal sheets and a sheet forming method to solve the above problems.

[0008] To achieve the above purpose, the present invention provides the following solutions:

[0009] A high-temperature forming vacuum envelope for forming metal sheets, comprising:

[0010] An inner soft vacuum envelope, with a cavity for accommodating a formed plate blank inside, and the cavity is used to be connected to a vacuum pumping device. Wherein, the cavity is evacuated by the vacuum pumping device to form a vacuum environment inside the cavity;

[0011] A hard envelope, wrapped outside the inner soft vacuum envelope.

[0012] Preferably, the inner soft vacuum envelope includes a copper foil placement layer, a composite hot melt adhesive film placement layer, a composite hot melt adhesive film covering layer, and a copper foil covering layer arranged in sequence from top to bottom;

[0013] The copper foil placement layer is fixedly connected to the composite hot melt adhesive film placement layer, the copper foil covering layer is fixedly connected to the composite hot melt adhesive film covering layer, and the cavity is located between the composite hot melt adhesive film placement layer and the composite hot melt adhesive film covering layer;

[0014] The edges of the copper foil placement layer and the copper foil covering layer are fixed.

[0015] Preferably, the hard envelope includes an upper sealing cover plate of the hard envelope, a lower placement bottom plate of the hard envelope, and a thermal expansion envelope fixing strip;

[0016] An accommodation cavity for accommodating the inner soft vacuum envelope is formed between the upper sealing cover plate of the hard envelope and the lower placement bottom plate of the hard envelope. The size of the accommodation cavity matches that of the inner soft vacuum envelope. The thermal expansion envelope fixing strip is in interference fit with the upper sealing cover plate of the hard envelope and the lower placement bottom plate of the hard envelope respectively, and the thermal expansion envelope fixing strip is used for fixing between the upper sealing cover plate of the hard envelope and the lower placement bottom plate of the hard envelope.

[0017] Preferably, a formed plate blank placement groove is formed in the middle of the lower placement bottom plate of the hard envelope. The inner soft vacuum envelope is placed in the formed plate blank placement groove, and the size of the formed plate blank placement groove matches the size of the inner soft vacuum envelope;

[0018] Interleaved sealing stepped grooves for the sliding and sealing of the upper sealing cover plate of the hard envelope are respectively formed on the left and right sides of the lower placement bottom plate of the hard envelope;

[0019] A fixing strip single - port card slot is formed at the front end of the lower placement bottom plate of the hard envelope along the sliding direction of the upper sealing cover plate of the hard envelope, and the fixing strip single - port card slot is in interference fit with one side of the thermal expansion envelope fixing strip;

[0020] One end of the single-port card slot of the fixed strip penetrates through the side wall of the lower placement bottom plate of the rigid sleeve, the other end of the single-port card slot of the fixed strip is in limiting fit with the fixed strip of the thermal expansion sleeve, a through hole is communicated at the limiting position of the single-port card slot of the fixed strip and the fixed strip of the thermal expansion sleeve, and the through hole is used for a ejector rod to pass through to eject the fixed strip of the thermal expansion sleeve out of the single-port card slot of the fixed strip.

[0021] A Z-shaped sealing step groove is formed at the tail end of the lower placement bottom plate of the rigid sleeve along the sliding direction of the upper sealing cover plate of the rigid sleeve, and the Z-shaped sealing step groove is used for sealing and limiting fit with the upper sealing cover plate of the rigid sleeve.

[0022] Preferably, staggered sealing steps for sliding and sealing fit with the staggered sealing step groove are formed on both sides of the upper sealing cover plate of the rigid sleeve;

[0023] An upper cover plate fixing groove is formed at the front end of the upper sealing cover plate of the rigid sleeve in the sliding direction, and the upper cover plate fixing groove is in interference fit with the other side of the fixed strip of the thermal expansion sleeve;

[0024] A Z-shaped sealing step is formed at the tail end of the upper sealing cover plate of the rigid sleeve in the sliding direction, and the Z-shaped sealing step is in sealing and limiting fit with the Z-shaped sealing step groove.

[0025] A sheet metal forming method uses the above-mentioned high-temperature forming vacuum sleeve for forming metal sheets, and includes the following steps:

[0026] S1. Place the forming plate blank in the cavity of the inner soft vacuum sleeve, and seal it after evacuating the cavity;

[0027] S2. Place the inner soft vacuum sleeve containing the forming plate blank in the rigid sleeve;

[0028] S3. Place the rigid sleeve in a hot press for processing;

[0029] S4. After cooling, separate the forming plate blank from the inner soft vacuum sleeve and the rigid sleeve to obtain a formed metal part.

[0030] Preferably, in S1, after an upper isolation graphite paper is covered on the upper surface of the forming plate blank and a lower isolation graphite paper is covered on the lower surface of the forming plate blank, it is placed in the cavity.

[0031] Preferably, in S1, first use a hot press sealer to seal three sides of the inner soft vacuum envelope, leaving an opening for placing the formed plate blank. After placing the formed plate blank into the inner soft vacuum envelope, use a hot press sealer to seal the edge of the opening and leave a vacuum pumping port adapted to a vacuum pump. Connect the vacuum pumping port to the vacuum pump, use the vacuum pump to evacuate the cavity. After the vacuum degree meets the forming requirements, use a hot press sealer to hot press seal the vacuum pumping port from the inside to the outside of the cavity, and then disconnect the vacuum pump.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] During use, by placing the formed plate blank in the cavity inside the inner soft vacuum envelope and evacuating the cavity to form a vacuum environment, the inner soft vacuum envelope serves as a guarantee for the first-layer vacuum environment, which can meet the vacuum requirements of the formed plate blank during hot pressing and cooling processes, and avoid the formed plate blank from contacting and oxidizing with air during hot pressing and cooling processes. Compared with the traditional use of a vacuum hot press for sheet forming, the application of the double-layer composite vacuum envelope can reduce the pumping cost, improve the pumping quality at the same time, and the double-layer composite vacuum envelope is easy to manufacture and can be used with a traditional hot press, reducing the cost of vacuum hot pressing of the formed plate blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings:

[0035] Figure 1 is a schematic structural diagram of the present invention;

[0036] Figure 2 is an exploded view of the schematic structure of the present invention;

[0037] Figure 3 is an exploded view of the structure of the inner soft vacuum envelope of the present invention;

[0038] Figure 4 is a top view of the structure of the hard envelope of the present invention;

[0039] Figure 5 is of the present invention Figure 4 in the A-A sectional structure diagram;

[0040] Figure 6 is of the present invention Figure 4 in the B-B sectional structure diagram;

[0041] Figure 7 It is the longitudinal parameter design drawing of the outer rigid fixing sheath of the present invention;

[0042] Figure 8 For the present invention Figure 5 The partial enlarged view at position C in it;

[0043] Figure 9 For the present invention Figure 5 The partial enlarged view at position D in it;

[0044] Figure 10 For the present invention Figure 6 The partial enlarged view at position E in it;

[0045] Among them, 1. Upper isolation graphite paper; 2. Forming plate blank; 3. Lower isolation graphite paper; 4. Inner soft vacuum sheath; 5. Sealing cover plate on the rigid sheath; 6. Thermal expansion sheath fixing strip; 7. Placing bottom plate under the rigid sheath; 401. Placing copper foil; 402. Placing composite hot melt adhesive film; 403. Covering composite hot melt adhesive film; 404. Covering copper foil; 501. Interleaved sealing step; 502. Z-shaped sealing step; 503. Upper cover plate fixing groove; 701. Through hole; 702. Single-port card slot for fixing strip; 703. Forming plate blank placing groove; 704. Interleaved sealing step groove; 705. Z-shaped sealing step groove; 706. Single-opening fixing strip guiding groove. Detailed implementation method

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] Refer to Figures 1 to 10 , the present invention discloses a high-temperature forming vacuum sheath for forming metal sheets, including:

[0049] The inner soft vacuum sheath 4 is provided with a cavity for accommodating the forming plate blank 2 inside, and the cavity is used to be connected to a vacuum pumping device. Among them, the cavity is evacuated by the vacuum pumping device to form a vacuum environment inside the cavity;

[0050] The rigid sheath is wrapped outside the inner soft vacuum sheath 4.

[0051] During use, by placing the formed plate blank 2 inside the cavity within the inner soft vacuum envelope 4, evacuating the cavity to create a vacuum environment, the inner soft vacuum envelope 4 serves as the guarantee for the first-layer vacuum environment, which can meet the vacuum requirements of the formed plate blank 2 during hot pressing and cooling processes, avoiding the oxidation of the formed plate blank 2 due to contact with air during hot pressing and cooling. Compared with the traditional use of a vacuum hot press for sheet forming, the application of the inner soft vacuum envelope 4 can reduce the air extraction cost, improve the air extraction quality at the same time, and the double-layer composite vacuum envelope is easy to manufacture and can be used with a traditional hot press, reducing the cost of vacuum hot pressing of the formed plate blank 2.

[0052] In a further optimized solution, the inner soft vacuum envelope 4 includes a copper foil 401 for placement, a composite hot-melt adhesive film 402 for placement, a composite hot-melt adhesive film 403 for covering, and a copper foil 404 for covering, which are arranged in sequence from top to bottom;

[0053] The copper foil 401 for placement is fixedly connected to the composite hot-melt adhesive film 402 for placement, the copper foil 404 for covering is fixedly connected to the composite hot-melt adhesive film 403 for covering, and the cavity is located between the composite hot-melt adhesive film 402 for placement and the composite hot-melt adhesive film 403 for covering;

[0054] The edges of the copper foil 401 for placement and the copper foil 404 for covering are fixed.

[0055] Through the above settings, during the hot pressing process, the composite hot-melt adhesive film 402 for placement and the composite hot-melt adhesive film 403 for covering are heated and melted to fill the gaps in the cavity formed by the copper foil 401 for placement and the copper foil 404 for covering, avoiding breakage and air leakage during the forming process, and greatly improving the stability of the vacuum sealing environment during the forming process.

[0056] Furthermore, the composite hot-melt adhesive film 402 for placement and the composite hot-melt adhesive film 403 for covering are preferably HR-8787 sodium silicate composite hot-melt adhesive films.

[0057] Furthermore, the design and preparation method of the inner soft vacuum envelope 4 is as follows:

[0058] The inner soft vacuum envelope 4 includes two layers of copper foil and two layers of sodium silicate composite hot-melt adhesive film,

[0059] First, fix the placed copper foil 401 and the placed composite hot melt adhesive film 402, and fix the covered copper foil 404 and the covered composite hot melt adhesive film 403. Taking the placed copper foil 401 and the placed composite hot melt adhesive film 402 with a smaller size as a reference, according to the design size requirements, use a hot pressing and sealing machine to fix the larger-sized covered composite hot melt adhesive film 403 and the covered copper foil 404 to the smaller-sized placed film according to the designed steps. Leave the placement opening of the forming plate blank 2 for the first edge sealing, and perform edge sealing on the remaining edges according to the designed size requirements. After the forming plate blank 2 is placed, perform the second edge sealing. The second edge sealing treatment leaves an air extraction port adapted to the vacuum pump. Use the vacuum pump to extract air from the inner soft vacuum envelope 4 of the second edge sealing until the vacuum degree requirement is met, and then perform the third edge sealing. For the third edge sealing, first use a hot pressing and sealing machine to seal the inside of the air extraction port close to the forming plate blank 2, and then while disconnecting the vacuum pump, seal the air extraction port completely from the inside to the outside to ensure the uniformity of the soft envelope around after three seals.

[0060] In a further optimized solution, the rigid envelope includes a rigid envelope upper sealing cover plate 5, a rigid envelope lower placement bottom plate 7, and a thermal expansion envelope fixing strip 6;

[0061] An accommodation cavity for accommodating the inner soft vacuum envelope 4 is formed between the rigid envelope upper sealing cover plate 5 and the rigid envelope lower placement bottom plate 7. The size of the accommodation cavity matches that of the inner soft vacuum envelope 4. The thermal expansion envelope fixing strip 6 is in interference fit with the rigid envelope upper sealing cover plate 5 and the rigid envelope lower placement bottom plate 7 respectively, and the thermal expansion envelope fixing strip 6 is used for fixing between the rigid envelope upper sealing cover plate 5 and the rigid envelope lower placement bottom plate 7.

[0062] In a further optimized solution, a forming plate blank placement groove 703 is opened in the middle of the rigid envelope lower placement bottom plate 7, and the inner soft vacuum envelope 4 is placed in the forming plate blank placement groove 703. The size of the forming plate blank placement groove 703 matches the size of the inner soft vacuum envelope 4;

[0063] Interleaved sealing step grooves 704 for the sliding sealing of the rigid envelope upper sealing cover plate 5 are respectively opened on the left and right sides of the rigid envelope lower placement bottom plate 7;

[0064] A fixing strip single-port card slot 702 is opened at the front end of the rigid envelope lower placement bottom plate 7 along the sliding direction of the rigid envelope upper sealing cover plate 5. The fixing strip single-port card slot 702 is in interference fit with one side of the thermal expansion envelope fixing strip 6;

[0065] One end of the fixing strip single-port card slot 702 penetrates through the side wall of the rigid envelope lower placement bottom plate 7, and the other end of the fixing strip single-port card slot 702 is in limit fit with the thermal expansion envelope fixing strip 6. A through hole 701 is communicated with the limit position of the fixing strip single-port card slot 702 and the thermal expansion envelope fixing strip 6. The through hole 701 is used for a push rod to pass through to push the thermal expansion envelope fixing strip 6 out of the fixing strip single-port card slot 702.

[0066] A bottom plate 7 is placed under the rigid sleeve. At the end of the bottom plate 7 along the sliding direction of the sealing cover plate 5 on the rigid sleeve, a Z-shaped sealing step groove 705 is provided, and the Z-shaped sealing step groove 705 is used for sealing and limiting cooperation with the sealing cover plate 5 on the rigid sleeve.

[0067] In a further optimized solution, staggered sealing steps 501 that are in sliding and sealing cooperation with the staggered sealing step grooves 704 are provided on both sides of the sealing cover plate 5 on the rigid sleeve;

[0068] At the front end of the sealing cover plate 5 on the rigid sleeve along the sliding direction, an upper cover plate fixing groove 503 is provided, and the upper cover plate fixing groove 503 is in interference fit with the other side of the thermal expansion sleeve fixing strip 6;

[0069] At the end of the sealing cover plate 5 on the rigid sleeve along the sliding direction, a Z-shaped sealing step 502 is provided, and the Z-shaped sealing step 502 is in sealing and limiting cooperation with the Z-shaped sealing step groove 705.

[0070] Furthermore, the bottom plate 7 placed under the rigid sleeve and the sealing cover plate 5 on the rigid sleeve are made of materials with the same or similar forming properties as the forming plate blank 2, reducing the influence of the rigid sleeve on the forming plate blank 2 during the forming process. The thermal expansion sleeve fixing strip 6 is made of a material with a slightly higher thermal expansion coefficient than the rigid sleeve. The thermal expansion sleeve fixing strip 6 is in interference fit with the rigid sleeve, facilitating the installation and disassembly of the thermal expansion sleeve fixing strip 6. At the same time, during the heating and forming process, the expansion of the thermal expansion sleeve fixing strip 6 can further squeeze the sealing edge of the inner soft vacuum sleeve 4 and the fixing edge between the bottom plate 7 placed under the rigid sleeve and the sealing cover plate 5 on the rigid sleeve, improving the sealing performance of the inner soft vacuum sleeve 4 and the structural stability of the outer rigid fixing sleeve during the forming process.

[0071] Furthermore, the bottom plate 7 placed under the rigid sleeve is provided with a forming plate blank placement groove 703 for placing the inner soft vacuum sleeve 4 covering the forming plate blank 2. Staggered sealing step grooves 704 are provided on the left and right sides of the forming plate blank placement groove 703 for sealing and fixing both sides in the direction of the air extraction port of the inner soft vacuum sleeve 4, and at the same time for the staggered sealing steps 501 provided on both sides of the sealing cover plate 5 on the rigid sleeve to slide in. On the upper and lower sides of the forming plate blank placement groove 703, a Z-shaped sealing step groove 705 and a single-opening fixing strip guiding groove 706 are respectively provided for sealing the inner soft vacuum sleeve 4 and fixing the sealing cover plate 5 on the rigid sleeve. A fixing strip single-port card slot 702 is provided at the extension end of the single-opening fixing strip guiding groove 706 for further fixing the thermal expansion sleeve fixing strip 6 to prevent the thermal expansion sleeve fixing strip 6 from shifting during the forming process. A through hole 701 serving as a fixing strip extraction mark is provided outside the fixing strip single-port card slot 702 for marking the position of the thermal expansion sleeve fixing strip 6 and facilitating the removal of the thermal expansion sleeve fixing strip 6 after forming.

[0072] On the hard jacket, the upper sealing cover plate 5 and the lower placement bottom plate 7 of the hard jacket are correspondingly provided with staggered sealing steps 501, Z-shaped sealing steps 502 and upper cover plate fixing grooves 503. At the same time, upper cover plate fixing grooves 503 are provided on the upper sealing cover plate 5 of the hard jacket. A mortise groove for placing the thermal expansion jacket fixing strip 6 is formed by splicing the upper cover plate fixing groove 503 and the single-opening fixing strip guiding groove 706. The thermal expansion jacket fixing strip 6, as a tenon, is inserted into the mortise groove, and is inserted into the mortise eye of the upper sealing cover plate 5 of the hard jacket through the open end of the single-opening fixing strip guiding groove 706 of the lower placement bottom plate, so that the upper and lower cover plates are connected and fixed.

[0073] A sheet metal forming method uses the above-mentioned high-temperature forming vacuum jacket for forming metal sheets, and includes the following steps:

[0074] S1. Place the forming blank 2 in the cavity of the inner soft vacuum jacket 4, and seal it after evacuating the cavity.

[0075] S2. Place the inner soft vacuum jacket 4 containing the forming blank 2 in the hard jacket.

[0076] S3. Place the hard jacket in a hot press for processing.

[0077] S4. After cooling, separate the forming blank 2 from the inner soft vacuum jacket 4 and the hard jacket to obtain a formed metal part.

[0078] In a further optimized solution, in S1, after the upper surface of the forming blank 2 is covered with the upper isolation graphite paper 1 and the lower surface of the forming blank 2 is covered with the lower isolation graphite paper 3, it is placed in the cavity.

[0079] In a further optimized solution, in S1, first use a hot press sealer to seal three sides of the inner soft vacuum jacket 4, leaving an opening for placing the forming blank 2. After placing the forming blank 2 in the inner soft vacuum jacket 4, use a hot press sealer to seal the edge of the opening and leave a vacuum pumping port adapted to the vacuum pump. The vacuum pumping port is connected to the vacuum pump. Use the vacuum pump to evacuate the cavity. After the vacuum degree meets the forming requirements, use a hot press sealer to thermally seal the vacuum pumping port from the inside to the outside of the cavity, and then disconnect the vacuum pump.

[0080] The manufacturing and working principle of the high-temperature forming vacuum jacket for large-size metal sheets, taking a rectangular structure as an example, includes the following steps:

[0081] S101. The specific process of the first edge sealing of the inner soft vacuum envelope 4 is as follows: Overlap the HR-8787 sodium silicate composite hot-melt adhesive films with designed sizes of one large and one small. Then, place a copper foil of corresponding size on each side. Fix three of the sealing edges at the designed peripheral size positions through a hot press sealer, leaving an opening for placing the plate.

[0082] S102. The specific process of the second edge sealing of the inner soft vacuum envelope 4 is as follows: Wrap the formed plate blank 2 with graphite paper to avoid direct contact between the formed plate blank 2 and the HR-8787 sodium silicate composite hot-melt adhesive film. Then, use the hot press sealer again to seal the opening of the inner soft vacuum envelope 4, leaving a vacuum pumping port adapted to the vacuum pump.

[0083] S103. The specific process of the third edge sealing of the inner soft vacuum envelope 4 is as follows: Connect the vacuum pumping port of the inner soft vacuum envelope 4 to the vacuum pump. After the vacuum degree meets the forming requirements, use the hot press sealer to thermally seal one end of the inner soft vacuum envelope 4 close to the formed plate blank 2. Then, disconnect the vacuum pump and completely thermally seal the inner soft vacuum envelope 4 from the inside to the outside along the vacuum pumping port, squeezing out the air in the pumping port while ensuring the consistency of the surrounding structure of the inner soft vacuum envelope 4.

[0084] S201. Place the raised covering end of the inner soft vacuum envelope 4 that has completed three edge sealings into the designed formed plate blank placement groove 703. The flat placement end of the inner soft vacuum envelope 4 fits with the sealing groove of the lower placement bottom plate 7 of the hard envelope. Then, use a long strip scraper to scrape and fit the four surrounding sealing edges of the inner soft vacuum envelope 4 with the staggered sealing step grooves 704, Z-shaped sealing step grooves 705, and single-opening fixed strip guide grooves 706 of the outer hard envelope respectively, so as to facilitate the placement and pressing of the upper sealing cover plate 5 of the hard envelope.

[0085] S202. Slowly push the upper sealing cover plate 5 of the hard envelope along the staggered sealing step groove 704 of the lower placement bottom plate 7 of the hard envelope to ensure the uniform discharge of the gas in the outer hard envelope and the extrusion and fitting with the inner soft vacuum envelope 4. Then, insert the thermal expansion envelope fixing strip 6 into the mortise holes of the upper sealing cover plate 5 of the hard envelope through the single-opening fixed strip guide groove 706. The tongue fits with the upper sealing cover plate 5 of the hard envelope, and the shoulder fits with the fixed strip single-port card slot 702 and the insertion end of the single-opening fixed strip guide groove 706 to connect and fix the upper and lower cover plates.

[0086] S301, place the prepared high-temperature forming vacuum sheath of large-sized metal sheet in large-sized hot forming equipment. During the heating process of the high-temperature forming vacuum sheath of large-sized metal sheet in the equipment, the heat expansion sheath fixing strip 6 expands due to the heat and fixes the sealing cover plate 5 on the hard sheath and the bottom plate 7 under the hard sheath more tightly together. At the same time, the HR-8787 water glass composite hot melt adhesive film in the soft vacuum sheath is heated. While the HR-8787 water glass ensures the stable connection of the inner soft vacuum sheath 4, part of the internal composite components melt and soften, and flow to fill every corner of the inner soft vacuum sheath 4, thereby ensuring the stability of the vacuum environment during the high-temperature forming process.

[0087] S302, in the common mold bending and rolling extension forming process, the sealing ends of the sealing cover plate 5 on the hard sleeve and the bottom plate 7 placed under the hard sleeve will be continuously squeezed and fitted, which can further enhance the sealing stability of the inner soft vacuum sleeve 4 on all sides. At the same time, the composite components of the internal HR-8787 water glass composite hot melt adhesive film that are partially melted by heat can also flow in time under the action of extrusion to fill the gaps with smaller extrusion pressure, thereby stably ensuring the airtightness of the overall structure.

[0088] S401, after the hot forming of the formed plate blank 2 is completed, the high-temperature formed vacuum sheath of the large-sized metal plate will be re-solidified during the overall cooling process. The solidified components can better fit the plate blank and the surrounding of the sheath, effectively ensuring the airtightness during the cooling process. At the same time, the heat expansion sheath fixing strip 6 will also cool and shrink. After the forming is completed, an iron nail is used to knock and insert it from the through hole 701, and the heat expansion sheath fixing strip 6 can be pushed out from the other end to a certain length. After that, the heat expansion sheath fixing strip 6 can be pulled out. After the upper and lower hard sheaths are separated, the inner soft vacuum sheath 4 is taken out, and it is cut along the junction of the soft sheath covering surface and the plate blank placement surface to take out the high-temperature vacuum formed product after vacuum thermoforming wrapped with graphite paper.

[0089] Furthermore, the dimension design method of the inner soft vacuum bag 4 comprises the following steps:

[0090] The first step is to place the single-side dimensions of the copper foil 401 and the composite hot melt adhesive film 402. The composition includes staggered sealing sections , Deformation reserved segment , and the length of the plate blank L. Among them, the staggered sealing section In the middle, two horizontal sealing sections as well as Take 0.5H to 2H according to the design experience, where H is the thickness of the slab. At the same time, to reduce the influence of the jacket on the forming of the slab, the sizes of the sealing structures at both ends of the inner soft vacuum jacket 4 should be symmetrically arranged, and the staggered section should be 0.5H, so that the jacket sealing sections of the inner soft vacuum jacket 4 are located at the bottom surface and the neutral layer of the slab respectively. Therefore, the total value range of the staggered sealing sections at both ends is 3H to 9H. The deformation reserved section Design according to the simulation results of abaqus and the sheet metal analysis of NX. Among them, rolling is the change value of length and thickness before and after deformation, and bending forming is the extension value of dimensions before and after deformation. At the same time, it is corrected in combination with actual experience. At the same time, a pre-estimated error value of the slab thickness H is reserved on both sides. According to the above design method, the unilateral sizes for placing the copper foil 401 and the composite hot melt adhesive film 402 are finally:

[0091] ;

[0092] Second step, the unilateral sizes for covering the composite hot melt adhesive film 403 and covering the copper foil 404 On the basis of the unilateral sizes for placing the copper foil 401 and the composite hot melt adhesive film 402 , there are two more slab thicknesses H. Therefore, the unilateral sizes for covering the composite hot melt adhesive film 403 and covering the copper foil 404 are designed as

[0093] ;

[0094] Third step, after determining the relevant sizes of the covering layer and the placing layer, take one side as the reference and hot-press and fix the distance of the staggered sealing section . Then place the copper foil 401 and the composite hot melt adhesive film 402 to leave the blank placing section and the deformation reserved section , cover the composite hot melt adhesive film 403 and cover the copper foil 404 to leave the corresponding blank covering section and the deformation reserved section . Then, according to the reserved dimensions, hot-press and form the other section from the inside to the outside to complete the dimension design and fixation of the inner soft vacuum jacket 4 in one direction. The dimension design of the non-vacuum pumping end in the other direction is similar to the previous dimension determination steps, and the dimensions of the vacuum pumping end are determined according to the existing vacuum pump. After completing the vacuum pumping, further trimming is carried out according to the size of the jacket to complete the design of the inner soft vacuum jacket 4.

[0095] Furthermore, the method for designing the size of the outer hard fixing jacket includes the following steps:

[0096] First step, in the thickness direction, the maximum thickness of the outer rigid fixed sleeve after assembly is 3H. Among them, at the position where the forming plate is placed, the thickness of the placing base plate 7 under the rigid sleeve is H, the thickness of the forming plate blank placing groove is H, and the thickness of the covering plate of the sealing cover plate 5 on the rigid sleeve is H. And to ensure the uniformity and reliability of the formed plate blank after being formed integrally with the sleeve, the design always ensures that the neutral layer of the plate blank is located in the middle layer of the sleeve thickness. At the same time, the thickness of the thermal expansion sleeve fixing strip is designed as H. At the same time, the lower end surface of the single-opening fixing strip guiding groove 706 is also arranged at the neutral layer of the plate blank to reduce the interference with the forming process of the plate blank.

[0097] Second step, in the width direction, the isolation dimension n between the forming plate blank and the fixing strip is taken as 0.5H to 1.5H to avoid the interference of the fixing strip on the deformation of the plate blank. At the same time, the width of the thermal expansion sleeve fixing strip 6 is designed as 1.5H, and its mating method with the outer rigid sleeve is a transition fit, and the connection method is a mortise and tenon connection, which is convenient for the installation and removal of the thermal expansion sleeve fixing strip 6. At the same time, it is ensured that the outer rigid fixed sleeve can be well fixed during the heating and forming process. The distance of the Z-shaped sealing section is designed in combination with the sleeve fixing section f of the outer rigid sleeve. At the same time, the peripheral width m of the sleeve should be kept consistent around, and it is ensured that to ensure the overall strength of the sleeve.

[0098] Third step, in the length direction, the middle working section of the sleeve is designed to be consistent with the soft sleeve, and the peripheral width is taken as m. At the same time, it is ensured that the overall design detail dimensions of the sleeve are consistent in the width and length directions.

[0099] Fourth step, the position of the fixing strip extraction mark should be consistent with the position of the thermal expansion sleeve fixing strip, and the width is taken as about 0.5H. There are no strict design dimension requirements, and it is only necessary to ensure that its positioning dimension is accurate and avoid interfering with the internal plate blank.

[0100] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0101] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-temperature forming vacuum envelope for forming metal sheets, characterized in that, Comprising: An inner soft vacuum envelope (4) with a cavity inside for accommodating a formed plate blank (2), and the cavity is used to be connected to a vacuum pumping device. Wherein, the cavity is evacuated by the vacuum pumping device to create a vacuum environment inside the cavity; A hard envelope, wrapped outside the inner soft vacuum envelope (4); The inner soft vacuum envelope (4) includes a copper foil for placement (401), a composite hot melt adhesive film for placement (402), a composite hot melt adhesive film for covering (403), and a copper foil for covering (404) arranged in sequence from top to bottom; The copper foil for placement (401) is fixedly connected to the composite hot melt adhesive film for placement (402), the copper foil for covering (404) is fixedly connected to the composite hot melt adhesive film for covering (403), and the cavity is located between the composite hot melt adhesive film for placement (402) and the composite hot melt adhesive film for covering (403); The edges of the copper foil for placement (401) and the copper foil for covering (404) are fixed; A design method for the inner soft vacuum envelope (4), comprising the following steps: The first step is the unilateral dimension of placing the copper foil (401) and placing the composite hot-melt adhesive film (402) The composition includes two staggered sealing segments , two deformation reserved segments , and a slab length segment L; The staggered seal section includes a horizontal seal section and a horizontal seal section as well as a staggered section ; Among them, the staggered seal section In it, the two horizontal seal sections and According to the design experience, it is taken as 0.5H to 2H, where H is the thickness of the slab; at the same time, to reduce the influence of the jacket on the forming of the slab, the left and right end seal structures of the inner soft vacuum jacket (4) are symmetrically arranged, and the staggered section is taken as 0.5H, so that the jacket seal sections of the inner soft vacuum jacket (4) are respectively located at the bottom surface of the slab and the neutral layer of the slab, and finally the total value range of the staggered seal sections at both ends is 3H to 9H; The horizontal sealing section is denoted as dimension a, the staggered section is denoted as dimension b, the horizontal sealing section is denoted as dimension c, and the deformation reserved section is denoted as dimension d; The deformation reserved section It is designed according to the simulation results of abaqus and the sheet metal analysis of NX, where rolling is the change value of length and thickness before and after deformation, bending forming is the dimension extension value before and after deformation, and it is corrected by combining actual experience. At the same time, an error estimate value of the thickness H of the slab is reserved on both sides. According to the above method, the single-side dimension of the placed copper foil (401) and the placed composite hot melt adhesive film (402) is finally obtained as follows: ； Step 2: Cover the unilateral dimensions of the composite hot melt adhesive film (403) and the covered copper foil (404). Based on the unilateral dimensions of the placed copper foil (401) and the placed composite hot melt adhesive film (402), there are two additional slab thicknesses H. Therefore, the unilateral dimensions of the covered composite hot melt adhesive film (403) and the covered copper foil (404) are as follows: ​ ； In the third step, after determining the relevant dimensions of the covering layer and the placement layer, with one side as the reference, hot-press and fix the staggered sealing section at a distance, and then leave a blank placement section and a deformation reserve section for the placed copper foil (401) and the placed composite hot-melt adhesive film (402) , and leave corresponding blank covering sections and deformation reserve sections for the covered composite hot-melt adhesive film (403) and the covered copper foil (404) , and then according to the reserved dimensions, hot-press and form the other section from the inside to the outside to complete the dimensional design and fixation of the inner soft vacuum envelope (4) in one direction. The dimensions of the vacuum pumping end are determined according to the existing vacuum pump. After the vacuum pumping is completed, further cutting can be carried out according to the size of the envelope; A preparation method for the inner soft vacuum envelope (4) is: First, fixedly connect the copper foil for placement (401) to the composite hot melt adhesive film for placement (402), and fixedly connect the copper foil for covering (404) to the composite hot melt adhesive film for covering (403). Taking the copper foil for placement (401) and the composite hot melt adhesive film for placement (402) as a reference, according to the design dimension requirements, use a hot press sealer to fix the composite hot melt adhesive film for covering (403) and the copper foil for covering (404) to the placement film according to the design steps. Leave a placement opening for the formed plate blank (2) during the first edge sealing, and seal the remaining edges according to the designed dimension requirements. After the formed plate blank (2) is placed, perform the second edge sealing. The second edge sealing treatment leaves an air extraction port adapted to a vacuum pump. Use the vacuum pump to evacuate the inner soft vacuum envelope (4) with the second edge sealing until the vacuum degree requirement is met, and then perform the third edge sealing. For the third edge sealing, first use a hot press sealer to seal the inside of the air extraction port close to the inner soft vacuum envelope (4), and then while disconnecting the vacuum pump, completely seal the air extraction port from inside to outside to ensure the uniformity of the periphery of the soft envelope after three seals.

2. The hot forming vacuum jacket for forming a metal sheet according to claim 1, characterized in that, The hard envelope includes an upper sealing cover plate (5) of the hard envelope, a lower placement bottom plate (7) of the hard envelope, and a thermal expansion envelope fixing strip (6); An accommodation cavity for accommodating the inner soft vacuum envelope (4) is formed between the upper sealing cover plate (5) of the hard envelope and the lower placement bottom plate (7) of the hard envelope. The size of the accommodation cavity matches that of the inner soft vacuum envelope (4). The thermal expansion envelope fixing strip (6) is in interference fit with the upper sealing cover plate (5) of the hard envelope and the lower placement bottom plate (7) of the hard envelope respectively, and the thermal expansion envelope fixing strip (6) is used for fixing between the upper sealing cover plate (5) of the hard envelope and the lower placement bottom plate (7) of the hard envelope.

3. The hot forming vacuum jacket for forming a metal sheet according to claim 2, wherein A bottom plate (7) is placed under the rigid sleeve. A forming plate blank placement groove (703) is formed in the middle of the bottom plate (7). The inner soft vacuum sleeve (4) is placed in the forming plate blank placement groove (703). The size of the forming plate blank placement groove (703) matches the size of the inner soft vacuum sleeve (4). On the left and right sides of the bottom plate (7) placed under the rigid sleeve, staggered sealing stepped grooves (704) for the sliding seal of the upper sealing cover plate (5) of the rigid sleeve are respectively formed. At the front end of the bottom plate (7) placed under the rigid sleeve along the sliding direction of the upper sealing cover plate (5) of the rigid sleeve, a fixed strip single-port card slot (702) is formed. One side of the fixed strip single-port card slot (702) is in interference fit with the thermal expansion sleeve fixed strip (6). One end of the fixed strip single-port card slot (702) penetrates through the side wall of the bottom plate (7) placed under the rigid sleeve. The other end of the fixed strip single-port card slot (702) is in limit fit with the thermal expansion sleeve fixed strip (6). A through hole (701) is communicated with the limit position of the fixed strip single-port card slot (702) and the thermal expansion sleeve fixed strip (6). The through hole (701) is used for a push rod to pass through to push out the thermal expansion sleeve fixed strip (6) from the fixed strip single-port card slot (702). At the tail end of the bottom plate (7) placed under the rigid sleeve along the sliding direction of the upper sealing cover plate (5) of the rigid sleeve, a Z-shaped sealing stepped groove (705) is formed. The Z-shaped sealing stepped groove (705) is used for sealing and limit fit with the upper sealing cover plate (5) of the rigid sleeve.

4. The hot forming vacuum jacket for forming metal sheets according to claim 3, characterized in that: On both sides of the upper sealing cover plate (5) of the rigid sleeve, staggered sealing steps (501) that are in sliding seal fit with the staggered sealing stepped grooves (704) are formed. At the front end of the upper sealing cover plate (5) of the rigid sleeve in the sliding direction, an upper cover plate fixing groove (503) is formed. The other side of the upper cover plate fixing groove (503) is in interference fit with the thermal expansion sleeve fixed strip (6). At the tail end of the upper sealing cover plate (5) of the rigid sleeve in the sliding direction, a Z-shaped sealing step (502) is formed. The Z-shaped sealing step (502) is in sealing and limit fit with the Z-shaped sealing stepped groove (705).

5. A sheet metal forming method, using the high-temperature forming vacuum envelope for forming metal sheets according to any one of claims 1-4, characterized in that, It includes the following steps: S1. Place the forming plate blank (2) in the cavity of the inner soft vacuum sleeve (4). After the cavity is evacuated, it is sealed. S2. Place the inner soft vacuum sleeve (4) containing the forming plate blank (2) in the rigid sleeve. S3. Place the rigid sleeve in a hot press for processing. S4. After cooling, separate the forming plate blank (2) from the inner soft vacuum sleeve (4) and the rigid sleeve to obtain a formed metal part.

6. A sheet metal forming method according to claim 5, characterized in that: In step S1, after an upper isolation graphite paper (1) covers the upper surface of the forming plate blank (2) and a lower isolation graphite paper (3) covers the lower surface of the forming plate blank (2), it is placed in the cavity.

7. A sheet metal forming method according to claim 5, characterized in that: In the step S1, first, use a hot press sealer to seal three sides of the inner soft vacuum envelope (4), leaving an opening for placing the formed plate blank (2). After placing the formed plate blank (2) into the inner soft vacuum envelope (4), use a hot press sealer to seal the edge of the opening and leave a vacuum pumping port adapted to a vacuum pump. The vacuum pumping port is connected to the vacuum pump. Use the vacuum pump to evacuate the cavity. After the vacuum degree meets the forming requirements, use a hot press sealer to hot press seal the vacuum pumping port from the inner side to the outer side of the cavity, and then disconnect the vacuum pump.

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