Deep cylinder thinning drawing die

Abstract

The invention relates to the technical field of metal plasticity, and provides a deep cylinder thinning drawing die which comprises a pre-forging assembly and a drawing assembly, the drawing assembly and the pre-forging assembly each comprise a die mounting base, and four fixing columns evenly distributed in a rectangular array are fixedly connected to the top of each die mounting base; and the tops of the four fixing columns are jointly and fixedly connected with a fixing plate, a hydraulic oil cylinder is installed at the top of the fixing plate, the output end of the hydraulic oil cylinder is fixedly connected with a lifting column, and the bottom of the lifting column is fixedly connected with a limiting plate. By arranging the first lower die, the second lower die and the third lower die of which the inner diameter sizes are gradually reduced, the step-by-step deformation of a material in the thinning and stretching process is realized in the continuous stretching process of a blank, so that the size and the shape of a product can be more accurately controlled, the deformation of single-time stretching is reduced, the machining precision is improved, and the machining quality is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of metal plasticity, and in particular to a deep barrel thinning and drawing die. Background Art

[0002] At present, the deep tube thinning and stretching process aims to thin thick plates by stretching to meet precision requirements and improve mechanical manufacturing efficiency. After the process is implemented, the surface finish of the deep tube is effectively improved, thereby improving product quality. This process can also make the wall thickness tend to be consistent and can accurately control the wall thickness of the deep tube, thereby ensuring the consistency of the appearance of the deep tube. Compared with the traditional casting process, it effectively shortens the processing time and improves the overall processing efficiency.

[0003] The authorization announcement in the prior art is: CN102266889B, and its name is: A continuous stamping thinning stretching process. The technical problem to be solved by the present invention is to provide a continuous stamping thinning stretching process, which makes full use of the advantages and disadvantages of gap stretching, thinning stretching, and flanging thinning stretching, so that the inner hole and outer circle diameter accuracy reaches IT11 level. The technical solution to this problem is: a continuous stamping thinning stretching process, the thickness t of the material to be processed is 0.5-2mm, and it is characterized by the following steps: cutting the flanged sheet according to the diameter Ds of the flange sheet shape; stretching 1-3, which is gap stretching; stretching 4, which is thinning stretching; stretching 5, which is R stretching; punching by conventional process; stretching 6, which is flanging thinning stretching.

[0004] However, the stamping thinning and stretching forming process in the patent and the prior art generally uses multiple stamping to extend in batches, and often requires the setting of multiple sets of dies and stamping tables. More dies and stamping tables will bring more problems, which will not only increase the workload of designers, but also take more time in later maintenance and overhaul. Therefore, a die that can directly perform composite stretching is urgently needed to avoid this situation;

[0005] In addition, during the use of the composite mold in the prior art, the lubricating oil on the material and the mold surface will gradually decrease during the continuous stamping process, which will increase the wear of the mold. Repeated filling of lubricating oil will cause the surface quality of the material to deteriorate, and it will also cause damage to the environment when the tank surface is cleaned later. Summary of the invention

[0006] The invention provides a deep barrel thinning stretching die, which solves the problems of low efficiency and uneven use of lubricating oil in the related art.

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

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a deep barrel thinning stretching die, comprising a pre-forging component and a stretching component, the stretching component and the pre-forging component both comprise a die mounting seat, the top of the die mounting seat is fixedly connected with four fixed columns evenly distributed in a rectangular array, the tops of the four fixed columns are commonly fixedly connected with a fixed plate, a hydraulic cylinder is installed on the top of the fixed plate, a lifting column is fixedly connected to the output end of the hydraulic cylinder, the bottom of the lifting column is fixedly connected with a limiting plate, four guide grooves are opened inside the limiting plate, the four fixed columns respectively pass through the inside of the four guide grooves, and the bottom of the limiting plate is fixedly connected with an upper die.

[0009] Preferably, the stretching assembly also includes a stretching die fixedly connected to the inside of the die mounting seat, the stretching die includes a die fixing seat, the inside of the die fixing seat is respectively fixedly connected with a first lower die, a second lower die and a third lower die evenly distributed in a rectangular array, the inner diameters of the first lower die, the second lower die and the third lower die are gradually reduced, and a limiting block is fixedly connected to the inside of the die fixing seat, the limiting block is located at the top of the first lower die, the inner diameter of the limiting block is larger than the inner diameter of the first lower die, and the die with gradually changing radius and inner diameter in multiple stages can well ensure that the material is deformed step by step during the thinning and stretching process, thereby more accurately controlling the size and shape of the product, helping to reduce the deformation of a single stretching, and improving the processing accuracy. In addition, arranging the multi-stage die inside the same die allows the material to be continuously processed inside the die without having to replace the die multiple times or interrupting the processing process, thereby improving production efficiency and dispersing the stress on the die during the stretching process, thereby extending the service life of the die.

[0010] Preferably, the top of the third lower mold and the top of the second lower mold are both provided with a lubrication assembly, the lubrication assembly includes a mounting block, a coating block is arranged inside the mounting block, four symmetrically arranged sliding grooves are opened inside the coating block, a guide shaft is slidably connected inside the sliding groove, a guide block is fixedly sleeved on the outer circumference of the guide shaft, the guide block is made of polyimide material, and a linkage block is fixedly sleeved on the outer circumference of the guide shaft;

[0011] The lubrication assembly also includes a linkage cable, and four symmetrically arranged trigger blocks are arranged on the top of the linkage cable. A slide groove is opened inside the trigger block, and the linkage block is slidably connected to the inside of the slide groove. A return spring is welded between the side wall of the slide groove and the linkage block. A pressure button is installed on the side wall of the slide groove, and the return spring is sleeved on the outer peripheral surface of the pressure button. The four pressure buttons are connected together through a linkage cable. Four oil outlets corresponding to the four coating blocks are arranged on the surface of the mounting block close to the coating block. A lubricating oil storage barrel is arranged on one side of the mold mounting seat, and a submersible pump is installed inside the lubricating oil storage barrel. An oil pipeline is connected between the output end of the submersible pump and the oil outlet hole. The submersible pump and the four pressure buttons are electrically connected. When the stretching mold is working, the guide shaft will move with the movement of the material, thereby driving the linkage block to slide in the slide groove, compressing the return spring and triggering the pressure button. When the pressure reaches a certain value, the pressure button will send a signal to the submersible pump to start the lubricating oil supply, thereby achieving the effect of automatic lubrication.

[0012] Preferably, an annular groove is provided inside the first lower die and the second lower die, and a filter is provided inside the annular groove, the top of the two annular grooves is flush with the inner surface of the first lower die and the second lower die, and a recovery barrel is provided on the top of the lubricating oil storage barrel, and return oil pipes are respectively provided between the two annular grooves and the recovery barrel, and the interior of the annular groove is connected with the interior of the recovery barrel through the return oil pipe, and the filter can effectively prevent the material from being stuck in the filter during the stretching process, causing damage to the mold, and in addition, the annular groove is provided to recover excess lubricating oil during thinning and stretching, and to apply it before the next extension step, so as to ensure that the lubricating oil on the surface of the blank is vertically uniform and appropriate each time the radius is changed for stretching, which can well ensure the quality of the product surface and reduce the risk of material rupture or deformation while protecting the mold.

[0013] Preferably, the pre-forging assembly also includes a pre-forging die fixedly connected to the inside of the die mounting seat, and a pre-forging groove is provided inside the pre-forging die. Through the setting of the pre-forging groove, the shape of the blank is pre-forged before each thinning and stretching, and its outer shape is forged to reduce the deformation amount of thinning and stretching in the next step.

[0014] Preferably, a deep barrel thinning and stretching die comprises the following steps:

[0015] S1: Blanking processing: select the appropriate size of the stretching die and pre-forging die according to the product size, and select the appropriate weight of the initial billet according to the product size;

[0016] S2: initial heating: placing the blank obtained in step S1 into a heating furnace for initial heating treatment to make the blank reach a temperature suitable for pre-forging;

[0017] S3: Pre-forging blank: pre-forging the blank heated in step S2 in a pre-forging assembly, and obtaining a pre-forged blank with a suitable shape by a pre-forging die;

[0018] S4: secondary heating: placing the prefabricated blank obtained in step S3 into the heating furnace again for secondary heating treatment to make the blank reach a temperature suitable for thinning and stretching;

[0019] S5: Thinning and stretching: The prefabricated blank heated in step S4 is placed in a stretching assembly for thinning and stretching treatment. The blank is thinned and stretched into shape by a stretching die to obtain a metal forging of a desired shape and size.

[0020] Preferably, the heating furnace in steps S2 and S4 is a resistance furnace, an induction furnace or a gas furnace, the heating temperature is 800-1200° C., and the heating time is 1-3 hours.

[0021] The working principle and beneficial effects of the present invention are:

[0022] 1. The present invention realizes step-by-step deformation of the material during the thinning and stretching process by arranging multiple lower dies, and arranging the first lower die, the second lower die and the third lower die with gradually decreasing inner diameters. This helps to more accurately control the size and shape of the product, reduce the deformation of a single stretch, improve the processing accuracy, and ensure the processing quality.

[0023] 2. The present invention arranges structures such as a lubrication component and cooperates with four guide wheels and pressure buttons. After the guide wheel is squeezed by the blank, the guide wheel will drive the linkage block to squeeze the pressure button. After all four pressure buttons are pressed, a submersible pump arranged inside the lubrication storage barrel will draw the lubricating oil and transport it to the coating block, and then coat it on the surface of the blank through the coating block, thereby ensuring that the surface lubricating oil is evenly distributed during each thinning and stretching.

[0024] 3. The present invention provides a recovery barrel and other structures, provides an annular groove on the mold, and provides a filter screen on the annular groove that is flush with the inner surface of the mold, so that the lubricating oil accumulated during extrusion can be recovered, the residual lubricating oil on the mold can be reduced, and the amount of residual lubricating oil when cleaning the mold can be reduced.

[0025] 4. The present invention pre-forges the blank through the pre-forging groove by setting up the pre-forging die and other structures, thereby reducing the deformation amount of the next step of thinning and stretching, which helps to improve the forming quality and processing efficiency of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 It is a schematic diagram of the overall structure of another perspective of the present invention;

[0029] Figure 3 is a side sectional view of the present invention;

[0030] Figure 4 For the present invention Figure 3 Enlarged view of the center labeled A;

[0031] Figure 5 It is a schematic diagram of the internal structure of the present invention;

[0032] Figure 6 It is a schematic diagram of the structure of the lubrication assembly of the present invention;

[0033] Figure 7 It is a schematic diagram of the guide block structure of the present invention;

[0034] Figure 8 It is a schematic diagram of the structure of the pre-forging die of the present invention.

[0035] In the figure: 1. mold mounting seat; 2. lubricating oil storage barrel; 3. fixed column; 4. limit plate; 5. lifting column; 6. fixed plate; 7. hydraulic cylinder; 8. upper mold; 9. limit block; 10. first lower mold; 11. second lower mold; 12. third lower mold; 13. recovery barrel; 14. ring groove; 15. mold fixing seat; 16. mounting block; 17. guide block; 18. coating block; 19. slide groove; 20. reset spring; 21. linkage block; 22. linkage cable; 23. pre-forging groove; 24. filter screen; 25. lubrication assembly; 26. trigger block; 27. pre-forging mold; 28. stretching mold. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] like Figures 1 to 8As shown, this embodiment proposes a deep barrel thinning stretching die, including a pre-forging component and a stretching component, both of which include a die mounting seat 1, the top of the die mounting seat 1 is fixedly connected with four fixed columns 3 evenly distributed in a rectangular array, the tops of the four fixed columns 3 are commonly fixedly connected with a fixed plate 6, the top of the fixed plate 6 is installed with a hydraulic cylinder 7, the output end of the hydraulic cylinder 7 is fixedly connected with a lifting column 5, the bottom of the lifting column 5 is fixedly connected with a limiting plate 4, the inside of the limiting plate 4 is provided with four guide grooves, the four fixed columns 3 respectively pass through the inside of the four guide grooves, and the bottom of the limiting plate 4 is fixedly connected with an upper die 8.

[0038] like Figures 1 to 8 As shown, the stretching assembly also includes a stretching die 28 fixedly connected to the inside of the die mounting seat 1, and the stretching die 28 includes a die fixing seat 15, and the inside of the die fixing seat 15 is respectively fixedly connected with a first lower die 10, a second lower die 11 and a third lower die 12 evenly distributed in a rectangular array, and the inner diameters of the first lower die 10, the second lower die 11 and the third lower die 12 are gradually reduced. The inside of the die fixing seat 15 is fixedly connected with a limit block 9, and the limit block 9 is located at the top of the first lower die 10. The inner diameter of the limit block 9 is larger than the inner diameter of the first lower die 10. Through the die with gradually changing radius and inner diameter in multiple stages, it can be well ensured that the material is deformed step by step during the thinning and stretching process, so as to more accurately control the size and shape of the product, which helps to reduce the deformation of a single stretching and improve the processing accuracy. In addition, the multi-stage die is set inside the same die, allowing the material to be continuously processed inside the die without changing the die multiple times or interrupting the processing process, thereby improving the production efficiency, and can also disperse the stress on the die during the stretching process, thereby extending the service life of the die.

[0039] like Figures 1 to 8 As shown, the top of the third lower mold 12 and the second lower mold 11 are both provided with a lubrication assembly 25, the lubrication assembly 25 includes a mounting block 16, a coating block 18 is arranged inside the mounting block 16, four symmetrically arranged sliding grooves are opened inside the coating block 18, a guide shaft is slidably connected inside the sliding groove, a guide block 17 is fixedly sleeved on the outer circumference of the guide shaft, the guide block 17 is made of polyimide material, and a linkage block 21 is fixedly sleeved on the outer circumference of the guide shaft;

[0040] The lubrication assembly 25 also includes a linkage cable 22, and four symmetrically arranged trigger blocks 26 are arranged on the top of the linkage cable 22. A slide groove 19 is opened inside the trigger block 26, and the linkage block 21 is slidably connected to the inside of the slide groove 19. A return spring 20 is welded between the side wall of the slide groove 19 and the linkage block 21. A pressure button is installed on the side wall of the slide groove 19. The return spring 20 is sleeved on the outer peripheral surface of the pressure button. The four pressure buttons are connected together through the linkage cable 22. Four contact springs are arranged on the surface of the mounting block 16 close to the coating block 18. 18 correspond to the oil outlet holes one by one, a lubricating oil storage barrel 2 is arranged on one side of the mold mounting base 1, a submersible pump is installed inside the lubricating oil storage barrel 2, an oil pipeline is connected between the output end of the submersible pump and the oil outlet hole, the submersible pump is electrically connected to four pressure buttons, when the stretching mold 28 is working, the guide shaft will move with the movement of the material, and then drive the linkage block 21 to slide in the slide groove 19, compress the reset spring 20 and trigger the pressure button, when the pressure reaches a certain value, the pressure button will send a signal to the submersible pump, start the lubricating oil supply, and achieve the effect of automatic lubrication.

[0041] like Figures 1 to 8 As shown, an annular groove 14 is provided inside the first lower die 10 and the second lower die 11, and a filter screen 24 is arranged inside the annular groove 14. The tops of the two annular grooves 14 are flush with the inner surfaces of the first lower die 10 and the second lower die 11. A recovery barrel 13 is arranged on the top of the lubricating oil storage barrel 2, and return oil pipes are respectively arranged between the two annular grooves 14 and the recovery barrel 13. The interior of the annular groove 14 is connected with the interior of the recovery barrel 13 through the return oil pipe. The filter screen 24 can effectively prevent the material from being stuck in the filter screen 24 during the stretching process, causing damage to the mold. In addition, the annular groove 14 is provided to recover excess lubricating oil during thinning and stretching, and to apply it before the next extension step, so as to ensure that the lubricating oil on the surface of the blank is vertically uniform and appropriate each time the radius is changed for stretching, which can well ensure the quality of the product surface and reduce the risk of material rupture or deformation while protecting the mold.

[0042] like Figures 1 to 8 As shown, the pre-forging assembly also includes a pre-forging die 27 fixedly connected to the inside of the die mounting base 1, and a pre-forging groove 23 is provided inside the pre-forging die 27. Through the setting of the pre-forging groove 23, the shape of the blank is pre-forged before each thinning and stretching, and its outer shape is forged to reduce the deformation amount of thinning and stretching in the next step.

[0043] In this embodiment, firstly, according to the size of the forging to be manufactured, lower dies of different sizes are selected, and different numbers of lower dies can also be selected according to the needs. By setting the lower dies that gradually decrease, the uniform flow of the material during the stretching process is ensured each time. As the inner diameter of the die gradually decreases, the tensile force on the material will gradually increase, thereby achieving a smoother deformation process;

[0044] After selecting a suitable die, a suitable blank is selected, and pre-treated by heating and the like to make it meet the pre-forging conditions. After the pre-treatment is completed, the blank is placed in the pre-forging groove 23 inside the pre-forging die 27, and the lower die is driven downward by starting the hydraulic cylinder 7 to extrude the blank, and the blank is pressed into the required pre-forging shape and size to obtain the pre-forged blank;

[0045] The pre-forged billet is further heated to reach the temperature requirement for forging. After the pretreatment before forging is completed, the pre-forged billet can be placed inside the limit block 9. The inner diameter of the limit block 9 is the same as the inner diameter of the pre-forging groove 23, which is convenient for positioning the billet and ensuring the accuracy of processing. After the billet is placed inside the limit block 9, the hydraulic cylinder 7 is started to drive the lifting column 5 and the upper die 8 to move downward, thereby extruding the billet. Because the inner diameter of the first lower die 10 is smaller than the outer diameter of the pre-forged billet, the material can gradually reduce its wall thickness while maintaining the height increase when subjected to external force. When the billet is extruded by the lower die, the oil on the billet will be squeezed and accumulated at the contact position between the billet and the lower die, and finally pass through the filter screen 24 and flow into the inside of the annular groove 14, and finally flow into the inside of the recovery barrel 13 through the return oil pipe to recover the excess oil.

[0046] After the blank passes through the first lower die 10, four guide blocks 17 will be squeezed downward at the same time. The guide blocks 17 can not only guide the direction of the blank, but also move backward after being squeezed by the blank, driving the linkage block 21 to enter the interior of the trigger block 26, thereby pressing the pressure button. After all four pressure buttons are pressed, the submersible pump installed inside the lubricating oil storage barrel 2 will be started. The submersible pump will absorb the lubricating oil inside the storage barrel and transport it to the four coating blocks 18 through the oil pipe. The coating block 18 is provided with a polyester fiber brush head, which can apply the lubricating oil to the blank in contact with it. After the lubricating oil is evenly coated, as the upper die 8 continues to be squeezed downward, the blank will continue to move downward, pass through the second lower die 11 and the third lower die 12, until the forging is completed.

[0047] like Figures 1 to 8 As shown Figure 4 As shown, the present invention proposes a stretching process of a deep barrel thinning stretching die of the above embodiment, comprising the following steps:

[0048] S1: Blanking process: Select the appropriate size of the stretching die 28 and the pre-forging die 27 according to the product size, and then select the appropriate weight of the initial blank according to the product size;

[0049] S2: initial heating: placing the blank obtained in step S1 into a heating furnace for initial heating treatment to make the blank reach a temperature suitable for pre-forging;

[0050] S3: Pre-forging billet: pre-forging the billet heated in step S2 in a pre-forging assembly, and forming a pre-forged billet of suitable shape by a pre-forging die;

[0051] S4: secondary heating: placing the prefabricated blank obtained in step S3 into the heating furnace again for secondary heating treatment to make the blank reach a temperature suitable for thinning and stretching;

[0052] S5: Thinning and stretching: The prefabricated blank heated in step S4 is placed into a stretching assembly for thinning and stretching treatment. The blank is thinned and stretched into shape by a stretching die 28 to obtain a metal forging of a desired shape and size.

[0053] like Figures 1 to 8 As shown, the heating furnace in steps S2 and S4 is a resistance furnace, an induction furnace or a gas furnace, the heating temperature is 800-1200° C., and the heating time is 1-3 hours.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A deep barrel thinning and stretching die, characterized in that: The invention comprises a pre-forging component and a stretching component, wherein the stretching component and the pre-forging component both comprise a die mounting seat (1), the top of the die mounting seat (1) is fixedly connected to four fixed columns (3) evenly distributed in a rectangular array, the tops of the four fixed columns (3) are commonly fixedly connected to a fixed plate (6), a hydraulic cylinder (7) is installed on the top of the fixed plate (6), the output end of the hydraulic cylinder (7) is fixedly connected to a lifting column (5), the bottom of the lifting column (5) is fixedly connected to a limit plate (4), the inside of the limit plate (4) is provided with four guide grooves, the four fixed columns (3) respectively pass through the inside of the four guide grooves, and the bottom of the limit plate (4) is fixedly connected to an upper die (8).

2. A deep barrel thinning and drawing die according to claim 1, characterized in that: The stretching assembly also includes a stretching die (28) fixedly connected to the inside of the die mounting seat (1), the stretching die (28) includes a die fixing seat (15), the inside of the die fixing seat (15) is respectively fixedly connected with a first lower die (10), a second lower die (11) and a third lower die (12) uniformly distributed in a rectangular array, the inner diameters of the first lower die (10), the second lower die (11) and the third lower die (12) gradually decrease, the inside of the die fixing seat (15) is fixedly connected with a limit block (9), the limit block (9) is located at the top of the first lower die (10), and the inner diameter of the limit block (9) is larger than the inner diameter of the first lower die (10).

3. A deep barrel thinning and drawing die according to claim 2, characterized in that: The top of the third lower mold (12) and the top of the second lower mold (11) are both provided with a lubrication assembly (25), the lubrication assembly (25) comprising a mounting block (16), a coating block (18) being arranged inside the mounting block (16), four symmetrically arranged sliding grooves being provided inside the coating block (18), a guide shaft being slidably connected inside the sliding groove, a guide block (17) being fixedly sleeved on the outer circumference of the guide shaft, the guide block (17) being made of a polyimide material, and a linkage block (21) being fixedly sleeved on the outer circumference of the guide shaft; The lubrication assembly (25) further comprises a linkage cable (22), the top of which is provided with four symmetrically arranged trigger blocks (26), a slide groove (19) is provided inside the trigger block (26), the linkage block (21) is slidably connected inside the slide groove (19), a return spring (20) is welded between the side wall of the slide groove (19) and the linkage block (21), a pressure button is installed on the side wall of the slide groove (19), and the return spring (20) is sleeved on the slide groove (19). On the outer peripheral surface of the pressure button, the four pressure buttons are connected together through a linkage cable (22); four oil outlet holes corresponding to the four coating blocks (18) are arranged on the surface of the mounting block (16) on the side close to the coating block (18); a lubricating oil storage barrel (2) is arranged on one side of the mold mounting seat (1); a submersible pump is installed inside the lubricating oil storage barrel (2); an oil pipeline is connected between the output end of the submersible pump and the oil outlet hole; the submersible pump and the four pressure buttons are electrically connected.

4. A deep barrel thinning and drawing die according to claim 3, characterized in that: The first lower mold (10) and the second lower mold (11) are each provided with an annular groove (14), a filter screen (24) is provided inside the annular groove (14), the tops of the two annular grooves (14) are flush with the inner surfaces of the first lower mold (10) and the second lower mold (11), a recovery barrel (13) is provided on the top of the lubricating oil storage barrel (2), and oil return pipes are respectively provided between the two annular grooves (14) and the recovery barrel (13), and the interior of the annular groove (14) is connected to the interior of the recovery barrel (13) through the oil return pipe.

5. A deep barrel thinning and drawing die according to claim 4, characterized in that: The pre-forging assembly further comprises a pre-forging die (27) fixedly connected to the inside of the die mounting seat (1), and a pre-forging groove (23) is provided inside the pre-forging die (27).

6. A deep tube thinning and stretching process, comprising a deep tube thinning and stretching die as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: blanking process: selecting a stretching die (28) and a pre-forging die (27) of appropriate size according to the product size, and selecting an initial blank of appropriate weight according to the product size; S2: initial heating: placing the blank obtained in step S1 into a heating furnace for initial heating treatment to make the blank reach a temperature suitable for pre-forging; S3: Pre-forging billet: pre-forging the billet heated in step S2 in a pre-forging assembly, and forming a pre-forged billet of suitable shape by a pre-forging die; S4: secondary heating: placing the prefabricated blank obtained in step S3 into the heating furnace again for secondary heating treatment to make the blank reach a temperature suitable for thinning and stretching; S5: Thinning and stretching: The prefabricated blank heated in step S4 is placed in a stretching assembly for thinning and stretching. The blank is thinned and stretched into shape by a stretching die (28) to obtain a metal forging of a desired shape and size.

7. A deep barrel thinning and stretching process according to claim 6, characterized in that: The heating furnace in steps S2 and S4 is a resistance furnace, an induction furnace or a gas furnace, the heating temperature is 800-1200° C., and the heating time is 1-3 hours.

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