Stamping equipment and pressing process for ultra-high-strength steel semi-spherical head

Abstract

The application relates to a stamping device and pressing process of a super-high-strength-steel hemispherical head, which comprises a fixed die, a movable die, a block round corner, a material dragging plate, a stretching punch, an ejection support, a bottom plate, the bottom plate is provided with a plurality of bottom plate through holes, the stretching punch is detachably connected with the bottom plate, the material dragging plate is arranged at the upper end of the ejection support, the ejection support is arranged at the upper end of the bottom plate through hole, the stretching punch is connected in the inner hole of the material dragging plate, the block round corner is detachably connected at the bottom of the fixed die, the inner hole bottom end of the block round corner is in an arc shape, the movable die is connected in the inner hole of the fixed die, a stamping blank is arranged on the material dragging plate, and the upper die set composed of the movable die, the fixed die and the block round corner is arranged above the stamping blank. The application has good pressing effect and high precision, and is suitable for stamping of hemispherical heads of super-high-strength-steel blanks with various thicknesses.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel material preparation and processing, in particular to a stamping equipment and pressing process for ultra-high strength steel hemispherical head. BACKGROUND

[0002] The pressure-resistant structure such as manned cabin and ballast water tank is a closed shell structure that can bear seawater external pressure, and can ensure the normal operation of non-pressure-resistant equipment and the health and safety of personnel. Internationally, titanium alloy is usually used to prepare pressure-resistant spherical shell. Due to the influence of factors such as material large-scale, homogeneity, deformation ability and weldability, the size specification of the pressure-resistant structure is limited, and it is difficult to meet the demand of large-scale and large-scale deep-sea operation equipment. In addition, the precision of the hemispherical head formed by pressing is low, the machining allowance is high, the processing amount is large, and the waste rate is high. In the preparation of steel pressure-resistant shell, only small-scale industrial production of hemispheres is currently explored in the world. There is little information on the process of hemispherical stamping equipment. The typical technical solutions are as follows: the Chinese patent with application number 201510345588.9 discloses a preparation process for pressure-resistant titanium alloy hemispheres for manned spherical deep-sea vehicles, which can manufacture large titanium alloy spherical deep-sea manned cabins. The Chinese patent with application number 202021232217.2 discloses an industrial production hemispherical stamping equipment, which solves the problem of automatic manufacturing of industrial production hemispheres. The Chinese patent with application number 202021232217.2 discloses a hemispherical stamping tool for hollow steel ball processing, which has simple device and is easy to maintain, improves the safety and efficiency of use.

[0003] However, the spherical pressure-resistant shell for deep-sea vehicle manufacturing requires very high manufacturing precision. The deep-sea vehicle manned spherical semi-pressure-resistant titanium alloy hemispherical stamping equipment with application number 201510345588.9 has low stamping precision. In order to leave enough machining allowance for later machining, the original plate material selected is relatively thick, resulting in low utilization of raw materials, large amount of machining, and the need for a larger tonnage oil press for stamping. In addition, the hemispheres manufactured by other hemispherical pressing process equipment disclosed at present are mostly small-scale industrial production hemispheres, which cannot be used for deep-sea vehicles. Ultimately, the following four problems are summarized:

[0004] 1. The pressing precision is generally low, the original plate material selected is relatively thick, resulting in low utilization of raw materials, large amount of machining, and the need for a larger tonnage press for stamping.

[0005] 2. A single set of molds can only press one size of hemispherical head, and cannot be adjusted and corrected in time according to demand changes.

[0006] 3. The existing molds have large initial defect inside corners during pressing, which cannot be repaired even by later machining, resulting in defects in the finally manufactured pressure-resistant spherical shell.

[0007] 4. Since most existing molds cannot be automatically demolded after pressing, it is necessary to use tools such as pry bars to lift the end cap and remove it. However, since the end cap has not been completely cooled at this time, the end cap will deform during the lifting process, which will ultimately affect the overall accuracy. Summary of the Invention

[0008] This invention provides a stamping equipment and pressing process for ultra-high strength steel hemispherical heads. The present invention has good pressing effect and high precision, and is suitable for stamping hemispherical heads of ultra-high strength steel slabs of various thicknesses.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] A stamping device for an ultra-high strength steel hemispherical head includes a fixed die, a movable die, a fillet block, a drag plate, an extension punch, an outlet support, and a base plate. The base plate has multiple through holes. The extension punch is detachably connected to the base plate. The drag plate is located on the upper end of the outlet support, which is located on the upper end of the through holes in the base plate. The extension punch passes through the inner hole of the drag plate. The fillet block is detachably connected to the bottom of the fixed die. The bottom end of the inner hole of the fillet block is arc-shaped. The movable die passes through the inner hole of the fixed die. The stamping blank is placed on the drag plate. The upper die assembly, consisting of the movable die, the fixed die, and the fillet block, is placed on the stamping blank.

[0011] Several connecting brackets are welded and fixed to the outer circumference of the rounded corner of the block, and the connecting brackets are connected to the fixed concave mold by bolts.

[0012] Several guide positioning blocks are bolted to the outer circumference of the drag plate. Each guide positioning block has a longitudinal protrusion, which forms a stamped positioning groove at the upper end of the drag plate. The outer circumference of the drag plate is also provided with a lifting pin hole.

[0013] The fixed die has an inner boss in its inner hole, and the moving die also has an outer boss on its outer circumference that mates with the inner boss.

[0014] The outer circumference of the fixed die is provided with a hydraulic press connection groove and a lifting pin hole.

[0015] The support includes an upper support pad, a bottom support plate, and a support column. One end of the support column is welded and fixed to the bottom support plate. The upper support pad is connected to the support column by connecting bolts. The bottom surface of the bottom support plate has a circular positioning protrusion that can be fitted into the through hole of the bottom plate.

[0016] A pressing process for a stamping equipment for an ultra-high strength steel hemispherical head includes the following steps:

[0017] 1) heating the stamping blank, the furnace temperature when the stamping blank is put into the furnace is greater than 600℃, the holding time is 1-5 min / mm, then heating to 850-1050℃ with the furnace, the holding time is 2-6 min / mm.

[0018] 2) the drag plate is lifted to above the extension punch by the out support, the heated stamping blank is placed on the end of the drag plate, the stamping machine is started, the upper die set is lowered to contact the stamping blank, then the pressure is started, with the downward pressure of the moving die, the out support is lowered with the downward pressure and pushes the drag plate, the stamping blank is deformed and gradually wrapped around the surface of the extension punch, at this time, the head stamping is semi-formed.

[0019] 3) when the temperature of the semi-formed head is below 800℃, the stamping is terminated, when the temperature is below 700℃, the upper and lower dies are separated, the stamping blank is heated to 850-1050℃ in the furnace again, the holding time is 2-6 min / mm, the stamping blank is taken out and placed on the lifted drag plate for secondary stamping.

[0020] 4) the drag plate is lowered until the semi-formed head contacts the extension punch, the upper die set is lowered to contact the semi-formed head, the size of the head is lowered, at this time, the semi-formed head is only lifted by the extension punch, the upper stamping machine is started to press from the upper die set, until the lower pressure contacts the drag plate, the stamping is completed.

[0021] 5) the initial pressure of the stamping machine when the upper die set contacts the blank is recorded, the pressure value of the stamping machine is recorded every 30-60 mm downward, until the pressing of the semi-spherical head is completed, then the change curve of the pressure value and the pressing depth value is drawn.

[0022] 6) after the stamping is completed, the temperature is lowered below 700℃ for demolding, the temperature is lowered below 600℃ to take out the spherical head from the extension punch, the taking out method is: lifting the upper die set, and lifting the drag plate by the out support, so that the pressed head is separated from the extension punch.

[0023] The diameter of the stamping blank before stamping is 800-3000 mm, and the thickness is 18-80 mm.

[0024] A lubricant is coated on the upper die set, the drag plate and the extension punch before stamping, the lubricant is made of 35%-45% graphite powder and 55%-65% machine oil.

[0025] The die steel HRC 50-55 HRC, △HRC <1 HRC, the quenched and tempered state room temperature impact energy kv2≥20 J, and meets 0.8≤X / Y≤1, 0.8≤Z / Y≤1, the annealed state room temperature impact isotropic performance: 0.8≤X / Y≤1, 0.8≤Z / Y≤1) is used for each part of the stamping equipment.

[0026] Compared with the prior art, the application has the beneficial effects that:

[0027] 1. Due to the use of a new secondary pressing process, the mold set is designed in a modular manner, and a hot work die steel material with high performance is used, different module parts can be replaced according to the size and characteristics of the material plate, the precision is improved by improving the pressing fit of the mold, the thickness of the required raw plate can be greatly reduced, the processing amount is reduced, and the required oil press tonnage is also lower.

[0028] 2. According to the different initial thicknesses of the material plate, different inner diameter movable concave dies can be replaced to press different thicknesses of the head, and different shapes of movable concave dies and extension punches, such as egg-shaped or other shapes, can also be replaced.

[0029] 3. Due to the addition of a fillet module, the initial defect inner fillet size can be minimized by suitable block fillet inward extrusion during pressing, so as to reduce the influence of the defect on the strength of the head.

[0030] 4. The movable material plate is used, and the material plate is lifted or lowered by the lower oil press to realize automatic mold loading or mold dragging. Since the material plate is uniformly stressed during the process, unnecessary deformation of the material plate during demolding can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a sectional view of a stamping head;

[0032] Figure 2 is a front view of a hemispherical stamping mold with the existing application number 201510345588.9;

[0033] Figure 3 is a front view of the application;

[0034] Figure 4 is a sectional view of the movable concave die of the application;

[0035] Figure 5 is a sectional view of the fixed concave die of the application;

[0036] Figure 6 is a top view of the fixed concave die of the application;

[0037] Figure 7 is a sectional view of the block fillet of the application;

[0038] Figure 8 is a top view of the block fillet of the application;

[0039] Figure 9 is a sectional view of the material plate dragging plate of the application;

[0040] Figure 10 is a top view of the material plate dragging plate of the application;

[0041] Figure 11 Figure 1 is a sectional view of the support for the invention;

[0042] Figure 12 Figure 2 is a sectional view of the assembled punch and base plate for the invention;

[0043] Figure 13 Figure 3 is a top view of the assembled punch and base plate for the invention;

[0044] Figure 14 Figure 4 is a schematic diagram of the hemispherical head stamping process for the invention;

[0045] Figure 15 Figure 5 is a flow chart of the hemispherical head stamping process;

[0046] Figure 16 Figure 6 is a flow chart of the hemispherical head stamping process for the invention.

[0047] Wherein: 1 - moving die, 2 - fixed die, 3 - block round corner, 4 - material dragging plate, 5 - punch, 6 - support, 7 - base plate, 8 - connecting bracket, 9 - bolt I, 10 - guide positioning block, 11 - bolt II, 12 - bolt III, 13 - fixed positioning block, 14 - base plate through hole, 15 - lifting pin hole, 16 - base body, 17 - support upper pad, 18 - connecting bolt, 19 - support column, 20 - support base plate, 22 - oil press connecting groove, 21 - inner round corner, 23 - positioning protrusion, 24 - 2600 ton oil press, 25 - hydraulic top rod, 26 - stamping blank. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer and more apparent, the specific embodiments of the present invention will be further described below in combination with examples. The following examples are used to specifically describe the present invention, and these examples are only a general description of the present invention and do not limit the present invention.

[0049] See Figure 3 A hemispherical head stamping device for ultra-high strength steel, comprising a fixed die 2, a moving die 1, a block round corner 3, a material dragging plate 4, a punch 5, a support 6, and a base plate 7, wherein the base plate 7 is provided with a plurality of base plate through holes 14, the punch 5 is detachably connected with the base plate 7, the material dragging plate 4 is seated on the upper end of the support 6, the support 6 is on the upper end of the base plate through hole 14, the punch 5 is inserted into the inner hole of the material dragging plate 4, the block round corner 3 is detachably connected at the bottom of the fixed die 2, the inner hole of the block round corner 3 is arc-shaped at the bottom end, the moving die 1 is inserted into the inner hole of the fixed die 2, a stamping blank 26 is placed on the material dragging plate 4, and the upper die set composed of the moving die 1, the fixed die 2 and the block round corner 3 is above the stamping blank 26.

[0050] The whole set of equipment from top to bottom is in turn movable die 1, fixed die 2, block round corner 3, material dragging plate 4, extension punch 5, out support 6, bottom plate 7. The upper die set in the whole set of device is composed of movable die 1, fixed die 2 and block round corner 3, and the lower die set is composed of material dragging plate 4, extension punch 5, out support 6 and bottom plate 7.

[0051] As shown in Figure 4 , the movable die 1 body is a semispherical recessed cylindrical component, which serves as a pressing semispherical outer surface, and can be replaced by movable dies with different inner diameters according to the requirements of pressing semispherical heads with different thicknesses. The movable die 1 is sleeved in the fixed die 2 and is installed together with the fixed die 2 on the upper oil press. The inner hole of the fixed die 2 is provided with an inner boss, and the outer circumference of the movable die 1 is provided with an outer boss which is lapped with the inner boss, and there is an assembly allowance between the inner boss and the outer boss.

[0052] As shown in Figure 5 , Figure 6 , the fixed die 2 body is an annular cylindrical component, which serves as a replaceable assembly movable die 1 with different shapes. Since the inner ring of the fixed die 2 leaves an assembly allowance for the up-down adjustment of the movable die 1, the position of the movable die 1 can be adjusted according to actual needs during assembly to achieve the best pressing state. The main function of the lifting pin shaft hole 15 is to facilitate the installation of the pin shaft for lifting the fixed die body, and the fixed die 2 is installed and fixed on the upper oil press.

[0053] As shown in Figure 7 , Figure 8 , the outer circumference of the block round corner 3 is welded and fixed with a plurality of connecting brackets 8, and the connecting brackets 8 are connected with the fixed die 2 through bolts I 9.

[0054] The block round corner 3 body is an annular cylindrical component, which serves as a replaceable pressing different inner round corners 21 (see Figure 1 ) according to the requirements of different stamping forming head inner round corners 21. The connecting brackets 8 are welded and fixed on the side surface of the block round corner 3, and the block round corner 3 is connected and fixed on the fixed die 2 through the bolts I 9.

[0055] As shown in Figure 9 , Figure 10 , a plurality of guide positioning blocks 10 are connected with the outer circumference of the material dragging plate 4 through bolts II 11, and the guide positioning blocks 10 are provided with longitudinal protrusions. The longitudinal protrusions of the plurality of guide positioning blocks 10 form a stamping positioning groove at the upper end of the material dragging plate 4. The stamping blank is placed in the stamping positioning groove. The inner side surface of the guide positioning block 10 is an inclined surface towards the center of the material dragging plate 4. When the upper die set runs downward, it plays a guiding role, so that the upper die set can have the same center as the material dragging plate 4.

[0056] The main body of the drag plate 4 is a ring-shaped columnar component, which supports the stamping blank 26. The guide positioning block 10 is installed on the main body of the drag plate 4 by bolt II 11. The stamping blank 26 can be limited by the guide positioning block 10 to prevent the stamping blank 26 from shifting position during the pressing process. The drag plate 4 is mounted on the support 6.

[0057] The outer circumference of the drag plate 4 is also provided with a lifting pin hole 15.

[0058] The outer circumference of the fixed die 2 is provided with a hydraulic press connection groove 22 and a lifting pin shaft hole 15.

[0059] like Figure 11 As shown, the outlet support 6 includes an outlet support upper pad 17, an outlet support base plate 20, and an outlet support column 19. One end of the outlet support column 19 is welded and fixed to the outlet support base plate 20. The outlet support upper pad 17 is connected to the outlet support column 19 by connecting bolts 18. The bottom surface of the outlet support base plate 20 has a circular positioning protrusion 23, which can be engaged with the through hole 14 of the base plate.

[0060] The main body of the support 6 is a dumbbell-shaped component with larger diameters at both ends and a smaller diameter in the middle. Its function is to support the material tray 4 to move up and down. The support 6 is welded to the support base plate 20 and the support column 19, and then fixed to the support upper pad 17 by connecting bolts 18. The support 6 is installed on the hydraulic push rod 25 of the lower hydraulic press through the through hole 14 in the base plate.

[0061] like Figure 12 , Figure 13 As shown, the main body of the extending punch 5 is a cylinder with one end in a hemispherical shape, used to press the inner surface of the hemisphere; the main body of the base plate 7 is a thick plate with six through holes 14 on its surface. The lower hydraulic press lifts the support 6 through the hydraulic jack 25. The base plate 7 serves to fix the extending punch 5 and support the entire device. The lifting pin hole 15 mainly facilitates the installation of the pin for lifting the base plate 7 and the main body of the extending punch 5. The extending punch 5 and the base plate 7 are connected and fixed by bolts III 12 through the fixing positioning block 13.

[0062] See Figure 14-16 A pressing process for a stamping equipment for ultra-high strength steel hemispherical heads includes the following steps:

[0063] 1) Cut the steel plate used for stamping into a circle according to the target head size, as the blank to be stamped; the diameter of the blank to be stamped is 800-3000mm, and the thickness can be selected by changing the moving die according to the requirements. The selectable thickness range is 18-80mm.

[0064] 2) Test run for a few minutes before pressing to confirm that the equipment is in good working order for stamping.

[0065] 3) Select the correct mold according to the requirements of the process documents. After the mold is installed, check the position and gap of the upper and lower molds, and tighten all fasteners to ensure safety.

[0066] 4) Before stamping, a lubricant can be applied to the mold. The lubricant is made of 40% graphite powder and 60% machine oil.

[0067] 5) Heating the stamping blank 26. Before heating, the thermocouple needs to be calibrated to ensure accurate recording by the measuring machine. When the stamping blank 26 enters the furnace, the furnace temperature is greater than 600℃. The holding time is 1 to 5 min / mm. Then, it is heated to 850 to 1050℃ with the furnace and the holding time is 2 to 6 min / mm before the stamping blank 26 can be taken out for pressing.

[0068] 6) such as Figure 15 The diagram shows the specific steps of the hemispherical stamping process. A 2600-ton hydraulic press is used for stamping. The material plate 4 is lifted onto the extension punch 5 by the support 6. The heated stamping blank 26 is placed on the upper end of the material plate 4, and the stamping blank 26 is aligned with the material plate 4 by the guide positioning block 10. The press is started, and when the upper die assembly is lowered to contact the plane of the stamping blank 26, pressure is applied. As the moving die 1 is pressed down, the support 6 is lowered along with the material plate 4 by the downward pressure. The stamping blank 26 is deformed and gradually wraps around the surface of the extension punch 5. At this time, the end cap is partially formed by stamping.

[0069] 7) Due to the cooling and shrinkage of the material, it tightly wraps around the upper die. When the temperature of the semi-formed head drops below 800℃, the stamping is terminated; when the temperature drops below 700℃, it is removed from the upper and lower dies, and the stamped blank 26 is reheated in the furnace to 850~1050℃, held for 2~6min / mm, and then taken out and placed on the raised drag plate 4 for secondary stamping.

[0070] 8) Lower the material tray 4 until the semi-formed end cap contacts the extension punch 5, then lower the upper concave die assembly so that it contacts the semi-formed end cap. During this process, ensure that the upper concave die assembly is aligned with the semi-formed end cap using the guide positioning block 10. After alignment, lower the material tray 4 according to the required final end cap size. At this point, the semi-formed end cap is only lifted by the extension punch 5. Start the upper stamping press and begin pressing with the upper concave die assembly until it contacts the material tray 4 and the stamping stops. The stamping is then complete.

[0071] 9) Record the initial pressure of the press when it contacts the blank in the upper concave die. Record the press pressure value every 30-60mm as the press moves down until the hemispherical head is pressed. Then draw a curve showing the change in pressure value and pressing depth.

[0072] 10) After stamping, when the temperature drops below 700℃, the upper and lower dies are removed. When the temperature drops below 600℃, the spherical head is removed from the extension punch 5. The removal method is as follows: the upper hydraulic press raises the upper concave die assembly, and at the same time, the hydraulic ejector rod 25 of the lower hydraulic press raises the support 6 to lift the material drag plate 4, so that the pressed head is separated from the extension punch 5. To prevent deformation, the head must not be placed at the air vent after removal to prevent uneven cooling and deformation.

[0073] Through dimensional inspection and performance comparison, the stamped ultra-high strength steel (≥600MPa) hemispherical head meets the design requirements. This indicates that the design and process are feasible.

[0074] All parts of the stamping equipment are made of high-isotropic hot work die steel with an HRC of 50-55 HRC, ΔHRC < 1 HRC, room temperature impact energy kv2 ≥ 20 J in the quenched and tempered state, and satisfying 0.8 ≤ X / Y ≤ 1, 0.8 ≤ Z / Y ≤ 1 in the annealed state (room temperature impact isotropic properties: 0.8 ≤ X / Y ≤ 1, 0.8 ≤ Z / Y ≤ 1).

[0075] Example:

[0076] High-grade isotropic hot work die steel (HRC: 50~52HRC, △HRC: 0.5~0.8HRC, average room temperature impact energy kv2≥23J in quenched and tempered state, and should satisfy X / Y=0.92, Z / Y≤1, annealed room temperature impact isotropic properties: 0.8≤X / Y≤1, 0.8≤Z / Y≤1) is used to manufacture various parts of the stamping equipment.

[0077] According to the target head size, the steel plate with a yield strength of 1000Mpa used for stamping is cut into a circle as the blank to be stamped; the diameter of the stamping blank is 914mm, and the thickness can be selected by changing the moving die as required, and the thickness can be 30mm.

[0078] After confirming the equipment is in good working order, select the correct mold according to the process documents. After mold installation, check the position and clearance of the upper and lower molds, and tighten all fasteners to ensure safety. Before stamping, lubricate the mold with 40% graphite powder and 60% machine oil. Before heating the blank steel plate, calibrate the thermocouples to ensure accurate recording by the measuring machine; the billet should be placed in the furnace at 650℃ and held for 30 minutes, then heated to 950℃ and held for 60 minutes before being removed for pressing. Use the following... Figure 10The specific steps of the hemispherical stamping process are as follows: The support 6 lifts the drag plate 4 onto the extension punch 5. The heated blank steel plate is then placed on the lower die ring of the drag plate 4 and aligned with the lower die ring via the guide positioning block 10. The stamping press is started until the upper die assembly descends to contact the plane of the blank steel plate, and then pressure is applied. The steel plate deforms as the moving die 1 presses down. The support 6 also descends with downward pressure, pushing against the drag plate 4, and the stamped blank 26 encloses the surface of the extension punch 5. At this point, the end cap has been stamped, but due to the cooling and shrinkage of the material, it tightly encloses the extension punch 5. Stamping should be stopped when the temperature of the end cap during forming drops below 800℃. When the temperature drops below 700℃, remove the upper and lower dies, reheat the stamped blank 26 to 900℃, hold for 60 minutes, and then place it on the raised drag plate 4 for a second stamping. Lower the drag plate 4 until the semi-formed head contacts the extending punch 5, then lower the upper concave die assembly so that it contacts the semi-formed head. During this process, ensure alignment using the guide positioning block 10. After alignment, lower the drag plate 4 according to the required final head size. The semi-formed head is now only lifted by the extending punch 5. Start the upper hydraulic press and begin pressing with the upper concave die assembly until it contacts the drag plate 4, at which point stamping is complete. Record the initial pressure of the upper concave die assembly contacting the blank. Record the press pressure value every 50mm of downward movement until the hemispherical head is pressed. After stamping, the die is removed when the temperature drops below 700℃. The spherical head can be carefully removed from the extension punch 5 when the temperature drops below 600℃. The upper hydraulic press raises the upper concave die assembly, and at the same time, the support 6 lifts the drag plate 4, so that the pressed head is removed from the extension punch 5.

[0079] The dimensions of the stamped hemispheres in the examples are shown in Table 1, and the performance test results of the stamped hemispheres in the examples are shown in Table 2.

[0080] Table 1. Dimensional Inspection (mm) of Examples

[0081]

[0082]

[0083] Table 2 Performance test results of the embodiments

[0084] Surface pickling passivation In accordance with the pattern and standard In accordance with Class A weld X-ray detection JB / T4730 III In accordance with Class B, C weld PT detection JB / T4730 II In accordance with VT detection In accordance with the pattern and standard In accordance with Container inner and outer surface quality In accordance with the pattern and standard In accordance with

[0085] Through dimensional inspection and performance comparison, the 1000MPa steel hemispherical head manufactured by stamping meets the design requirements. This indicates that the design and process are feasible.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A pressing process for a stamping equipment for ultra-high strength steel hemispherical heads, characterized in that, The stamping equipment includes a fixed die, a movable die, a fillet block, a slip plate, an extension punch, an outlet support, and a base plate. The base plate has multiple through holes. The extension punch is detachably connected to the base plate. The slip plate is located on the upper end of the outlet support, which is located on the upper end of the through holes in the base plate. The extension punch passes through the inner hole of the slip plate. The fillet block is detachably connected to the bottom of the fixed die. The bottom end of the inner hole of the fillet block is arc-shaped. The movable die passes through the inner hole of the fixed die. The stamping blank is placed on the slip plate. The upper die assembly, consisting of the movable die, the fixed die, and the fillet block, is placed on the stamping blank. The support is installed on the hydraulic push rod of the lower hydraulic press through the through hole in the base plate; Several connecting brackets are welded and fixed to the outer circumference of the rounded corner of the block, and the connecting brackets are connected to the fixed concave mold by bolts; Several guide positioning blocks are bolted to the outer circumference of the drag plate. The guide positioning blocks are provided with longitudinal protrusions, and the longitudinal protrusions of the several guide positioning blocks form a stamped positioning groove at the upper end of the drag plate. The pressing process of the stamping equipment for ultra-high strength steel hemispherical heads includes the following steps: 1) Heat the stamping slab. When the stamping slab enters the furnace, the furnace temperature is greater than 600℃. Hold the temperature for 1 to 5 minutes / mm, and then heat it to 850 to 1050℃ with the furnace. Hold the temperature for 2 to 6 minutes / mm. 2) The support lifts the slab onto the punch, and the heated blank is placed on the upper part of the slab. The press is started, and the upper die descends to contact the blank plane and begins to apply pressure. As the moving die presses down, the support, along with the downward pressure, pushes the slab down and the blank is lowered. The blank deforms and gradually wraps around the surface of the punch. At this time, the end cap is half-formed. 3) When the temperature of the semi-formed head drops below 800℃, stop the stamping; when the temperature drops below 700℃, remove the upper and lower dies, reheat the stamped blank to 850~1050℃ in the furnace, hold for 2~6min / mm, and then take it out and place it on the raised drag plate for secondary stamping. 4) Lower the material tray until the semi-formed end cap contacts the extension punch, then lower the upper concave die assembly so that it just contacts the semi-formed end cap. Lower the material tray according to the required final end cap size. At this time, the semi-formed end cap is only lifted by the extension punch. Start the upper punching machine to start pressing by the upper concave die assembly until it is pressed down to contact the material tray and the punching is stopped. The punching is completed. 5) Record the initial pressure of the press when it contacts the blank in the upper concave die. Record the press pressure value every 30-60mm as the press moves down until the hemispherical head is pressed. Then draw a curve showing the change in pressure value and pressing depth. 6) After stamping, demold when the temperature drops below 700℃, and remove the spherical end cap from the extension punch when the temperature drops below 600℃. The removal method is as follows: raise the upper concave die assembly, and at the same time, the support lifts the drag plate to make the pressed end cap separate from the extension punch.

2. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The outer circumference of the drag plate is also provided with a lifting pin hole.

3. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The fixed die has an inner boss in its inner hole, and the moving die has an outer boss on its outer circumference that mates with and overlaps with the inner boss.

4. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The outer circumference of the fixed die is provided with a hydraulic press connection groove and a lifting pin hole.

5. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The support includes an upper support pad, a bottom support plate, and a support column. One end of the support column is welded and fixed to the bottom support plate. The upper support pad is connected to the support column by connecting bolts. The bottom surface of the bottom support plate has a circular positioning protrusion that can be fitted into the through hole of the bottom plate.

6. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The diameter of the stamped slab before stamping is 800-3000 mm, and the thickness is 18-80 mm.

7. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, Before stamping, a lubricant is applied to the upper concave die, the material guide plate, and the extension punch. The lubricant is made by mixing 35% to 45% graphite powder and 55% to 65% machine oil.

8. The pressing process of the stamping equipment for an ultra-high strength steel hemispherical head according to claim 1, characterized in that, The die steel used for each part of the stamping equipment has an HRC of 50-55 HRC, ΔHRC < 1 HRC, a room temperature impact energy kv2 ≥ 20 J in the quenched and tempered state, and satisfies 0.8 ≤ X / Y ≤ 1, 0.8 ≤ Z / Y ≤ 1. The room temperature impact isotropic properties in the annealed state are 0.8 ≤ X / Y ≤ 1, 0.8 ≤ Z / Y ≤ 1.

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