A method and a forming die for roll-bulging a large-aspect-ratio cylindrical part

Abstract

The application discloses a large height-diameter ratio cylinder roll drawing forming method and a forming die, the roll drawing forming die comprises a support frame, a core die and a plurality of roll dies, the plurality of roll dies are installed on the support frame, the inside of the roll die is provided with a plurality of rollers, and the plurality of rollers are surrounded to form a cylindrical roll drawing cavity; when the cylinder is prepared, first, a blank is sleeved on the core die, then the core die is driven to go down, sequentially passes through the roll drawing cavities of the plurality of roll dies, the wall thickness of the blank is thinned, the blank is axially elongated to form the cylinder, then a flange is pressed out at the top cylinder opening position of the cylinder through a flanging disc, then a material blocking plate is sleeved on the core die, the material blocking plate is fixed with the support frame, and the bottom surface of the material blocking plate is in contact with the flange, then the core die is driven to go up, and the core die can be smoothly drawn out from the cylinder, so that the separation of the core die and the cylinder is realized, the large height-diameter ratio cylinder is prepared by adopting the roll die drawing technology, the process is simple, the efficiency is high, the cost is low, the demolding operation is simple, and the rapid and efficient demolding can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of plastic working of metal materials, and particularly relates to a roll drawing forming method and forming die for a large height-diameter ratio cylindrical part. BACKGROUND

[0002] At present, the method for preparing a large height-diameter ratio thin-walled cylindrical part is to prepare it through spinning technology, such as patents CN202111420387.2 and CN202011257209.8. The method is to fix one end of a cylindrical blank which is placed on a spinning device spindle or a core die by a hydraulic clamping device, drive the cylindrical blank along the same axis by the core die or the device spindle, and simultaneously perform multi-pass axial feeding and circumferential rotation movement by using a single or multiple spinning wheel dies, so that the wall thickness of the cylindrical part is continuously reduced with the continuous rotation of the spinning wheel, the side wall is continuously elongated, the continuous local plastic deformation of the cylindrical blank wall is realized, and then a large height-diameter ratio thin-walled cylindrical part is prepared.

[0003] However, the method for preparing a large height-diameter ratio cylindrical part through the existing spinning technology has the following defects:

[0004] 1. The cylindrical part after spinning is closely attached to the core die, especially under the condition of hot forming, the material shrinkage intensifies the adhesion of the cylindrical part to the core die, and the traditional demolding method relies on friction force for axial pulling separation. Since the wall thickness of the cylindrical part is extremely thin (less than 10 mm), the wrapping force is strong, the friction force is large, and it is difficult to separate the cylindrical part from the core die, so it is difficult to realize efficient and rapid demolding, the demolding is laborious and time-consuming, and the traditional forced demolding method is also easy to cause deformation or cracking of the cylindrical opening of the cylindrical part;

[0005] 2. Multiple spinning passes are required, the spinning wheel needs to be repositioned for each spinning pass, the spinning wheel trajectory needs to be accurately controlled, the deformation amount of each pass is small, and intermediate annealing is also required frequently, the processing parameters need to be frequently adjusted, time and labor are consumed, the process is complex, and the preparation period is long;

[0006] 3. The sliding friction between the spinning wheel and the blank easily causes surface scratches, a large amount of lubricant is required, and the pollution cost is increased.

[0007] 4. The spinning machine equipment is expensive, and the production cost is high. SUMMARY

[0008] The purpose of the present application is to provide a roll drawing forming method and forming die for a large height-diameter ratio cylindrical part, which uses roll die drawing technology to prepare a large height-diameter ratio cylindrical part, has simple process, high efficiency and low cost, and the demolding operation is simple, so that rapid and efficient demolding can be realized.

[0009] To achieve the above purpose, the solution of the present application is: a roll drawing forming method for a large height-diameter ratio cylindrical part, comprising the following steps:

[0010] S1, preparing a blank: according to the size and shape of the cylindrical part to be prepared, the cylindrical part blank is prepared, and the blank is heated;

[0011] S2, preparing a mold: forming a cylindrical part by using a roll drawing forming mold, the roll drawing forming mold comprises a support frame, a core mold and a plurality of roll molds, the plurality of roll molds are detachable and arranged in upper and lower rows on the support frame, each roll mold is a one-pass extrusion process, and a plurality of rollers are arranged in the interior of each roll mold, the rolling surface of the roller is an arc-shaped surface concave inward, a plurality of rollers are distributed circumferentially to form a cylindrical roll drawing cavity, the diameter of the roll drawing cavity is smaller than the diameter of the blank, and the diameters of the roll drawing cavities of the plurality of roll molds decrease from top to bottom; when the mold is installed, the core mold is first installed on the press, and then the plurality of roll molds are installed on the support frame, the centers of the roll drawing cavities of the plurality of roll molds and the center of the core mold are on the same axis;

[0012] S3, roll drawing forming: the preheated blank is sleeved on the core mold, the core mold is driven to move downward by the press, the core mold drives the blank to pass through the roll drawing cavities of all the roll molds in sequence, so that the plurality of rollers on the roll mold rotate passively at the same speed to the center of the roll drawing cavity to roll the blank, the pass compression rate of the roll mold is 8%-35%, the wall thickness of the blank is thinned to form a cylindrical part, and the multi-pass roll drawing forming of the blank is completed;

[0013] S4, flanging: driving the core mold to move upward, the cylindrical part is withdrawn from the support frame with the core mold, then the roll molds on the support frame are taken out, then the core mold is disassembled, an annular flanging disc is installed on the core mold, the diameter of the flanging disc decreases from top to bottom and the peripheral side surface of the flanging disc is an arc-shaped surface concave inward, the bottom of the flanging disc is inserted between the top of the cylindrical part and the core mold, then the core mold is placed in the support frame, a backing plate is installed in the support frame to support the core mold and the cylindrical part, then the flanging disc is pressed downward by the press, so that the top part of the cylindrical part is flanged along the peripheral side surface of the flanging disc to form a flange;

[0014] S5, demolding: after the flanging is completed, the press is driven to move upward, the flanging disc is disassembled, the blanking plate is sleeved on the core mold, and the blanking plate is fixed with the support frame, the lower end surface of the blanking plate is in contact with the top flange of the cylindrical part, then the core mold is installed on the press, the core mold is driven to move upward to pull out the core mold from the cylindrical part, then the blanking plate is disassembled, and the cylindrical part is taken out from the support frame.

[0015] Further, in step S2, the central axes of the upper rollers and the central axes of the lower rollers in the two adjacent roll molds arranged in upper and lower rows are distributed at a certain angle.

[0016] Further, in steps S2-S3, the number of the roll dies is four, including a first pass roll die, a second pass roll die, a third pass roll die, and a fourth pass roll die, and the pass compression rates of the first pass roll die, the second pass roll die, the third pass roll die, and the fourth pass roll die are 25%-35%, 20%-28%, 15-25%, and 8%-23%, respectively; the support frame is provided with two installation grooves arranged side by side in the up-down direction, the first and second pass roll dies are installed in the two installation grooves, respectively, then the blank is sleeved on the core die, the core die is driven to move downward, the core die drives the blank to pass through the roll drawing cavities of the first and second pass roll dies, respectively, to complete the first and second pass roll drawing, then the core die is driven to move upward, the cylindrical part is withdrawn from the support frame with the core die, then the first and second pass roll dies are removed, the third and fourth pass roll dies are installed in the two installation grooves, respectively, the core die is driven to move downward, the core die drives the blank to pass through the roll drawing cavities of the third and fourth pass roll dies, respectively, to complete the third and fourth pass roll drawing.

[0017] Further, in steps S2-S3, four roll wheels are arranged in each roll die, and the central axes of the roll wheels of the first and third passes are arranged at an angle of 45° with the central axes of the roll wheels of the second and fourth passes.

[0018] Further, in steps S2-S3, the roll die has a box-shaped structure of a cuboid, the middle part of the roll die is provided with an installation cavity penetrating through the up-down direction and used for installing the roll wheels, the support frame has a cuboid frame, the inside of the support frame is hollow, and the inner side wall is provided with an installation groove used for installing the roll die, one side wall of the support frame is provided with a square installation opening in communication with the installation groove, and the roll die is inserted into or extracted from the installation groove through the installation opening.

[0019] Further, in step S2, the upper part of the core die is provided with a pull rod section having a smaller diameter than the middle part and the lower part of the core die, a disc is first sleeved on the bottom of the pull rod section, and then the core die is installed on the press; after the roll drawing forming in step S3, the disc is located on the inner side of the top of the cylindrical part, so that the disc is removed from the core die before the installation of the flanging disc in step S4, so that a space is left between the top of the cylindrical part and the pull rod section for the bottom of the flanging disc to be inserted.

[0020] Further, in steps S2-S5, the lower part of the press is fixed with an upper die plate, the lower part of the upper die plate is fixed with an upper die plate backing plate, the top of the pull rod section of the core die is detachably installed on the bottom of the upper die plate backing plate through a fixing pin, the core die is removed by detaching the pull rod section from the upper die plate backing plate, and the flanging disc is placed on a ring-shaped backing plate, the upper die plate backing plate is driven downward by the press, and the flanging disc is driven to move downward.

[0021] Further, in step S5, the middle part of the material blocking plate is provided with a through hole for the core mold to pass through, and the core mold is sleeved on the pull rod section through the through hole, and the draft angle of the core mold is 0.8°.

[0022] Further, in step S5, the top of the support frame is provided with a circular opening in communication with the inside, the core mold and the cylindrical part enter the support frame from the circular opening, the outer periphery of the circular opening is provided with bolt mounting holes to fix the material blocking plate and the support frame through bolts, and the bottom of the support frame is provided with an ejection rod, after the material blocking plate is disassembled, the cylindrical part is ejected upward out of the support frame through the ejection rod, and then the flange and other size allowance of the cylindrical part are trimmed to make the size of the cylindrical part meet the design requirements, and then the cylindrical part is subjected to solid solution and aging treatment.

[0023] The application also provides a large height-diameter ratio cylindrical part roll drawing forming die, which comprises a support frame, a core mold and a plurality of roll molds.

[0024] After the above scheme is adopted, the application has the following advantages:

[0025] 1. The application adopts a staged demolding mode, a flange is formed at the top of the cylindrical part through a flanging process to form a mechanical stop structure, a material blocking plate is installed on the flange, the material blocking plate is fixed with the support frame, then the core mold is driven to move upward, the material blocking plate forms a mechanical clamping structure which contacts with the flange to prevent the axial movement of the cylindrical part, and provides a reverse support point, so that the demolding force is converted from pure friction force to structural limiting force, and in the demolding process, the material blocking plate provides rigid ejection force to bear most of the demolding force, so that the core mold and the cylindrical part can be smoothly separated, and the demolding operation is convenient and simple, and the success rate is high.

[0026] 2. The formed flange is convenient to abut against the material blocking plate, increases the separation trend of the cylindrical part and the core mold, and forms an annular reinforcing rib structure at the edge of the cylindrical part to strengthen the cylinder port structure of the cylindrical part, so that the flange can disperse stress and improve the anti-deformation ability of demolding when the core mold is separated and the cylindrical part is ejected upward, and deformation or cracking caused by the traditional axial pulling demolding mode is avoided.

[0027] 3、The present application realizes the thinning of the circumferential dimension and the increase of the axial dimension of the blank by the roller die applying radial pressure on the cylindrical part, belongs to the continuous deformation process, the metal fluidity is strong, the rolling friction between the roller die and the blank, the friction coefficient is small, the drawing force is small, the amount of lubricant can be reduced, the cost can be reduced, and the probability of breakage, cracking and tearing can be reduced, the yield can be improved; in addition, the energy consumption is low, and the service life of the die can be prolonged.

[0028] 4、The pass compression rate (wall thickness thinning rate) of the roller die can reach 35%, the roller drawing pass and the intermediate annealing frequency can be reduced, the processing parameters do not need to be frequently adjusted, the process is simple, the preparation period is short, and the production efficiency is high.

[0029] 5、The roller die can be detachably installed in the support frame, the pass deformation amount of the cylindrical part and the roller drawing frequency can be adjusted as required, and cylindrical parts of different sizes can be prepared.

[0030] 6、In the process that the roller and the blank are in contact, the blank is subjected to the radial extrusion force of the roller, and the metal is easy to accumulate at the gap between the rollers when flowing, forming longitudinal flash, so that in the two adjacent roller dies arranged in the upper and lower directions, the central axis of the upper roller and the central axis of the lower roller are distributed at a certain angle, that is, a certain angle is arranged between the upper and lower rollers in the horizontal direction, after the roller drawing of the next pass, the longitudinal flash formed by the roller drawing of the previous pass can be eliminated, and when the last pass is drawn, the size of the longitudinal flash formed is very small and can be ignored, and subsequent flash trimming process is not needed, improving the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the front view of the cylindrical part of the present application;

[0032] Figure 2 It is Figure 1 the sectional view in A-A direction;

[0033] Figure 3 It is the front view of the blank of the present application;

[0034] Figure 4 It is the sectional view in B-B direction of the present application;

[0035] Figure 5 It is the structure schematic view of the roller drawing forming die of the present application;

[0036] Figure 6 It is the three-dimensional structure schematic view of the first and third pass roller dies of the present application;

[0037] Figure 7 It is the top view of the first and third pass roller dies of the present application;

[0038] Figure 8Fig. 2 is a perspective view of the second and fourth pass roller die of the present application;

[0039] Figure 9 Fig. 3 is a top view of the second and fourth pass roller die of the present application;

[0040] Figure 10 Fig. 4 is a perspective view of the support frame of the present application;

[0041] Figure 11 Fig. 5 is a sectional view of the support frame of the present application;

[0042] Figure 12 Fig. 6 is a schematic view of the upward movement of the core die after the roll forming of the present application;

[0043] Figure 13 Fig. 7 is a sectional view of the disc placed on the core die of the present application;

[0044] Figure 14 Fig. 8 is a schematic view of the formed flange of the present application;

[0045] Figure 15 Fig. 9 is a sectional view of the formed flange of the present application;

[0046] Figure 16 Fig. 10 is a schematic view of the separation of the core die and the cylindrical part of the present application;

[0047] Figure 17 Fig. 11 is a sectional view of the separation of the core die and the cylindrical part of the present application.

[0048] Explanation of reference numerals:

[0049] 1, cylindrical part; 11, flange; 2, blank; 3, support frame; 31, mounting groove; 32, mounting hole; 33, circular opening; 34, bolt mounting hole; 35, ejector rod; 4, core die; 41, pull rod section; 42, fixing pin; 5, roller die; 51, roller; 52, roll forming cavity; 53, mounting cavity; 6, press; 7, upper die plate; 71, upper die plate backing plate; 8, disc; 9, flange disc; 91, annular backing plate; 10, material blocking plate. DETAILED DESCRIPTION

[0050] The present application will be described in detail below in conjunction with the accompanying drawings and specific examples.

[0051] The cylindrical part 1 with a large height-diameter ratio to be prepared in the present application has a shape as shown in Fig. 1. Figures 1-2As shown, the bottom of the shown has a boss structure, the wall thickness is very thin, using the existing spinning process, need multi-pass spinning, and each pass deformation is smaller, also need frequent intermediate annealing, need frequent debugging processing parameters, time-consuming and labor-consuming, complex process, long preparation cycle, in addition, the spun cylindrical part 1 and the core mold 4 are closely fitted, it is difficult to separate the cylindrical part 1 and the core mold 4, and separation is also easy to cause the deformation or cracking of the cylinder port of the cylindrical part 1, for this, the present application provides a large height-diameter ratio cylindrical part roll drawing forming method and forming die.

[0052] As shown in the figure, Figures 2-11 The roll drawing forming die includes a support frame 3, a core mold 4 and a plurality of roll dies 5, the plurality of roll dies 5 are detachable and arranged in upper and lower rows on the support frame 3, each roll die 5 is a one-pass extrusion process, each roll die 5 is provided with a plurality of rollers 51 inside, the rolling surface of the roller 51 is an inner concave arc surface, the plurality of rollers 51 are distributed in the circumferential direction to form a cylindrical roll drawing cavity 52, the diameter of the roll drawing cavity 52 is smaller than the diameter of the blank 2, and the diameters of the roll drawing cavities 52 of the plurality of roll dies 5 decrease from top to bottom, and the diameter of the roll drawing cavity 52 of the last pass is the diameter of the cylindrical part 1 to be prepared; the centers of the roll drawing cavities 52 of the plurality of roll dies 5 and the center of the core mold 4 are on the same axis. During roll drawing, only the core mold 4 is installed on the press 6, then the preheated blank 2 is sleeved on the core mold 4, then the core mold 4 is driven downward by the press 6, the core mold 4 drives the blank 2 to pass through the plurality of roll drawing cavities 52, in this process, the plurality of rollers 51 passively roll towards the center of the roll drawing cavity 52 at the same speed, the blank 2 is radially extruded by the rollers 51, so that the circumferential dimension of the blank 2 is thinned and the axial dimension is increased, forming the required cylindrical part 1.

[0053] The cylindrical part 1 can be roll formed by the roll drawing forming die, which belongs to a continuous deformation process, the metal flowability is strong, the friction coefficient between the roll die 5 and the blank 2 is small, the drawing force is small, the amount of lubricant can be reduced, the cost can be reduced, and the probability of breakage, cracking and tearing can be reduced, and the yield can be improved.

[0054] It should be noted that in the contact process between the roller 51 and the blank 2, the blank 2 is subjected to radial extrusion force by the roller 51, and the metal is easy to accumulate at the gap between the rollers 51 when flowing, forming longitudinal flash, so that in the two adjacent roll dies 5 arranged in upper and lower rows, the upper roller 51 and the lower roller 51 are arranged at a certain angle between the central axes, that is, a certain angle is arranged in the horizontal direction between the upper and lower rollers 51 of the two passes, after the roll drawing of the next pass, the longitudinal flash formed by the roll drawing of the previous pass can be eliminated, and the size of the longitudinal flash formed in the last pass is very small and can be ignored, so that the subsequent flash trimming process is not needed, and the production efficiency is improved.

[0055] Referring to Figures 6-11In the embodiment, four roller dies 5 are preferably arranged, including a first-pass roller die, a second-pass roller die, a third-pass roller die, and a fourth-pass roller die, wherein the roller cavity 52 gradually decreases in diameter from the first pass to the fourth pass, that is, the pass compression ratio gradually decreases. The support frame 3 is provided with two installation grooves 31 arranged side by side in the up-down direction. The first-pass and second-pass roller dies are first installed in the two installation grooves 31 respectively, then the blank 2 is sleeved on the core die 4, the core die 4 is driven to move downward to complete the first-pass and second-pass roller drawing, then the first-pass and second-pass roller dies are removed, and the third-pass and fourth-pass roller dies are installed to complete the third-pass and fourth-pass roller drawing. The pass compression ratio (wall thickness reduction rate) of the conventional spinning process is generally 10%-15% (calculated according to the patent CN202111420387.2), and the preparation process of the present application adopts the roller 51 to roll and draw the cylindrical part 1. The compression ratio of each pass is 8-35%, and the highest can reach 35%. The compression ratio is greater than that of the conventional spinning process, and the forming requirement of the cylindrical part 1 can be completed through four passes of roller drawing.

[0056] Further, the number of rollers 51 of the roller die 5 can be arranged as needed. The fewer the number of rollers 51, the greater the pressure borne by a single roller 51, which is easy to cause local wear of the roller 51, affecting the service life of the roller 51 and the surface forming quality of the cylindrical part 1. The more the number of rollers 51, the more complex the structure, and the higher the manufacturing cost. Considering the above factors, as shown in Figures 6-9 In the embodiment, the roller die 5 of each pass is preferably provided with four rollers 51, and the rolling surface of each roller 51 is a quarter of a circular arc surface. Four rollers 51 are used for rolling, so that the circumferential stress of the cylindrical part 1 is uniform, the metal deformation is more uniform, and the forming quality is improved. While ensuring the forming precision of the cylindrical part 1, the cost is controlled within a lower range.

[0057] Preferably, the distribution of the rollers 51 of the first pass and the third pass is as shown in Figures 6-7 The distribution of the rollers 51 of the second pass and the fourth pass is as shown in Figures 8-9 The present application arranges the central axes of the rollers 51 of the first pass and the third pass to be distributed at an angle of 45° with the central axes of the rollers 51 of the second pass and the fourth pass, which ensures that the flash generated by the first-pass and third-pass roller drawing is uniformly eliminated by the rollers 51 of the second pass and the fourth pass, and the compression ratio of the fourth pass is low, so that the size of the flash is extremely small and can be ignored.

[0058] For emphasis, please refer to Figures 6-11The roller die 5 is a cuboid box structure, and a middle part of the roller die 5 is provided with an installation cavity 53 which is vertically through and is used for installing a roller 51, the support frame 3 is a cuboid frame, the inside of the support frame 3 is hollow, and an inner side wall is provided with an installation slot 31 which is used for installing the roller die 5, one side wall of the support frame 3 is provided with a square installation opening 32 which is communicated with the installation slot 31, the roller die 5 is inserted into or extracted from the installation slot 31 through the installation opening 32, and the drawer-like pulling structure is convenient for disassembling and assembling the roller die 5.

[0059] A top part of the support frame 3 is provided with a circular opening 33 which is communicated with the inside, a center of the circular opening 33 is on the same axis as that of the roller pulling cavity 52, the core die 4 and the cylindrical part 1 enter into the support frame 3 from the circular opening 33, and a bottom part of the support frame 3 is provided with an ejection rod 35, after the cylindrical part 1 is formed, the core die 4 is separated from the cylindrical part 1, then the cylindrical part 1 is upwardly ejected from the support frame 3 through the ejection rod 35, and the demolding operation is facilitated.

[0060] In addition, a lower part of the press 6 is fixed with an upper die plate 7, a lower part of the upper die plate 7 is fixed with an upper die plate backing plate 71, an upper part of the core die 4 is provided with a pulling rod section 41 which has a smaller diameter than the middle part and the lower part of the core die 4, and the pulling rod section 41 of the core die 4 is detachably installed on the bottom of the upper die plate backing plate 71 through a fixing pin 42. The core die 4 is not a pure cylindrical structure, and has a roller pulling inclination of 0.8°, that is, the side wall of the core die 4 is not vertical, but has a certain inclination angle, so that the core die 4 is a circular table structure, and the generatrix slightly inclines to the vertical plane and forms an angle of 0.8°, and the design of the roller pulling inclination is to make the core die 4 and the cylindrical part 1 more easily separated.

[0061] By using the roller pulling forming die, the application provides a roller pulling forming method of a large height-diameter ratio cylindrical part, and the method comprises the following steps:

[0062] S1, preparing a blank 2: according to the size and shape of the cylindrical part 1 to be prepared, the cylindrical part blank 2 is prepared, the material can adopt 2A12 aluminum alloy, a boss can be prepared at the bottom of the blank 2 through a reverse extrusion process, and the structure of the blank 2 is as shown in Figures 3-4 Then, the blank 2 is subjected to a heating treatment, and specifically, the blank 2 can be heated to 400℃ for 6 hours by using an electric resistance furnace.

[0063] S2, preparing a die: first, the core die 4 is subjected to the same heating treatment as the blank 2, the roller die 5 is kept at room temperature, a disc 8 is sleeved on the bottom of the pulling rod section 41, and the structure of the disc 8 installed on the pulling rod section 41 is as shown in Figure 13 Then, the core die 4 is installed on the press 6, and then the first and second pass roller dies are inserted into the installation slot 31 of the support frame 3 through the installation opening 32, and the center of the roller pulling cavity 52 of the first and second pass roller dies is on the same axis as that of the core die 4.

[0064] S3. Roll forming, specifically including the following steps:

[0065] First and second rolling processes: The preheated billet 2 is inserted into the core mold 4, such as... Figure 5 As shown, the core mold 4 is driven downward by the press 6, and the core mold 4 drives the blank 2 to pass through the rolling cavities 52 of the first and second rolling dies in sequence. The compression rates of the first and second rolling dies are 25%-35% and 20%-28% respectively, which reduces the thickness of the blank 2 and increases the axial dimension.

[0066] Third and fourth rolling passes: After the first and second rolling passes are completed, the drive mandrel 4 moves upward, causing the mandrel 4 to pull the blank 2 out of the support frame 3. Then, the first and second rolling dies are pulled out from the mounting groove 31 in the support frame 3 through the mounting port 32, and the third and fourth rolling dies are installed in the mounting groove 31 of the support frame 3. Then, the drive mandrel 4 moves downward, causing the blank 2 to pass through the rolling cavities 52 of the third and fourth rolling dies in sequence. The compression rates of the third and fourth rolling dies are 15-25% and 8%-23% respectively, which reduces the wall thickness of the blank 2 again and extends the axial dimension again, forming a cylindrical part 1.

[0067] S4, Flanging 11: After roll forming, drive the core mold 4 upward, causing the cylindrical part 1 to exit the support frame 3 upward with the core mold 4, and the exit state is as follows. Figure 12 As shown, then remove the roller mold 5 from the support frame 3, and then remove the core mold 4, that is, remove the pull rod section 41 of the core mold 4 from the upper template pad 71, and remove the disc 8 on the pull rod section 41, so that there is a certain gap between the top of the cylindrical part 1 and the pull rod section 41; then as shown Figures 14-15 As shown, an annular flange 9 is installed on the core mold 4. The diameter of the flange 9 gradually decreases from top to bottom, and the peripheral side of the flange 9 is a concave arc surface. The bottom of the flange 9 is inserted into the gap between the top of the cylindrical part 1 and the pull rod section 41. Then, the core mold 4 is placed in the support frame 3. A pad (which can be inserted into the mounting groove 31, not shown in the figure) is installed inside the support frame 3 to support the core mold 4 and the cylindrical part 1. Then, an annular pad 91 is placed on the flange 9. The press 6 drives the upper template pad 71 to press down the annular pad 91, thereby driving the flange 9 to move downward, so that the top opening of the cylindrical part 1 is turned outward along the peripheral side of the flange 9 to form a flange 11.

[0068] S5. Demolding: After flanging 11 is completed, drive the press 6 upward, remove the annular pad 91, and remove the flanging disc 9; then proceed as follows Figures 16-17As shown, the baffle plate 10 is sleeved on the core mold 4, the middle part of the baffle plate 10 is provided with a through hole for the core mold 4 to pass through, the baffle plate 10 is sleeved on the pull rod section 41 through the through hole, and the baffle plate 10 is fixed with the support frame 3, preferably a bolt mounting hole 34 is arranged on the outer periphery of the circular opening 33 at the top of the support frame 3, the baffle plate 10 is fixed with the support frame 3 through the bolt, after being fixed, the lower end surface of the baffle plate 10 is in contact with the top flange 11 of the cylindrical part 1, then the core mold 4 is installed on the press 6, the core mold 4 is driven to go up, the core mold 4 is smoothly pulled out from the cylindrical part 1 through the abutment of the baffle plate 10 and the cylindrical part 1 and with the help of the draft angle of the core mold 4, so that the cylindrical part 1 is separated from the core mold 4, then the baffle plate 10 is disassembled, the cylindrical part 1 is taken out from the support frame 3, and subsequent processes are carried out.

[0069] Further, in step S5, the bottom of the support frame 3 is provided with an ejection rod 35, after the baffle plate 10 is disassembled, the cylindrical part 1 can be ejected upward out of the support frame 3 through the ejection rod 35.

[0070] After the cylindrical part 1 is taken out, the flange 11 and other size allowances of the cylindrical part 1 need to be trimmed, so that the size of the cylindrical part 1 meets the design requirements, then the cylindrical part 1 is subjected to solid solution and aging treatment, and the specific steps include: the cylindrical part 1 is heated to 505℃, and kept for 1 hour, then rapidly quenched with water above 40℃, immediately after quenching, the cylindrical part 1 is subjected to aging treatment, and is heated to 180℃, kept for 8 hours, and then air cooled to room temperature.

[0071] In the above forming method, the disc 8, the flange disc 9 and the baffle plate 10 are all provided with threaded holes matched with lifting ring bolts, and the disc 8, the flange disc 9 and the baffle plate 10 can be moved and disassembled through the lifting ring bolts.

[0072] The following is further illustrated through specific examples:

[0073] Example one:

[0074] A cylindrical part with an outer diameter of 159.5mm, a wall thickness of 2.4mm and a height of 500mm is prepared, and a blank with an outer diameter of 166.4mm, a wall thickness of 5.85mm and a height of 140mm is prepared for roll drawing, and the drawing coefficient, pass compression rate, drawing force and diameter and wall thickness of the blank of each pass are shown in Table 1.

[0075] Table 1 - drawing data table of example 1

[0076]

[0077] Example two:

[0078] A cylindrical piece with an outer diameter of 163.5 mm, a wall thickness of 4.4 mm and a height of 500 mm is prepared, and a blank with an outer diameter of 166.4 mm, a wall thickness of 14.4 mm and a height of 180 mm is prepared for roll drawing, the drawing coefficient, pass compression rate, drawing force and diameter and wall thickness of the blank of each pass are shown in Table 2.

[0079] Table 2 - drawing data table of Example 2

[0080]

[0081] Example Three:

[0082] A cylindrical piece with an outer diameter of 167.5 mm, a wall thickness of 6.4 mm and a height of 500 mm is prepared, and a blank with an outer diameter of 194.96 mm, a wall thickness of 20.13 mm and a height of 160 mm is prepared for roll drawing, the drawing coefficient, pass compression rate, drawing force and diameter and wall thickness of the blank of each pass are shown in Table 3.

[0083] Table 3 - drawing data table of Example 3

[0084]

[0085] It can be known from the above examples that the pass compression rate of the four-pass roll drawing forming can reach more than 20%, compared with the spinning process with a compression rate of 10%-15%, the number of drawing passes and intermediate annealing can be reduced, the preparation efficiency is improved, and the drawing force is controlled within 10-100 t, most of the drawing force can be controlled below 80 t, at the same time of high compression rate, the drawing force is small, the energy consumption is less, the probability of breakage, cracking and tearing can be reduced, and the yield is improved.

[0086] The above only describes the preferred embodiments of the present application, and is not intended to limit the design of the present application, and any equivalent changes made according to the key design of the present application fall within the protection scope of the present application.

Claims

1. A method of roll forming a large aspect ratio cylindrical part, characterized by, The method comprises the following steps: S1, preparing a blank: according to the size and shape of the cylindrical part to be prepared, a cylindrical part blank is prepared, and the blank is subjected to a heating treatment; S2, preparing a mold: a cylindrical part is formed by using a roll forming mold, the roll forming mold comprises a support frame, a core mold and a plurality of roll molds, the plurality of roll molds are detachable and arranged in upper and lower rows on the support frame, each roll mold is a one-pass extrusion process, the number of roll molds is four, including a first-pass roll mold, a second-pass roll mold, a third-pass roll mold and a fourth-pass roll mold; a plurality of rollers are arranged in the interior of each roll mold, the rolling surface of the rollers is an inwardly concave arc surface, the plurality of rollers are circumferentially distributed to form a cylindrical roll forming cavity, the diameter of the roll forming cavity is smaller than the diameter of the blank, and the diameters of the roll forming cavities of the plurality of roll molds gradually decrease from top to bottom; when the mold is installed, the core mold is first installed on a press, and then the plurality of roll molds are installed on the support frame, the centers of the roll forming cavities of the plurality of roll molds and the center of the core mold are on the same axis; the upper part of the core mold is provided with a pull rod section with a diameter smaller than the middle part and the lower part of the core mold, a disc is first sleeved on the bottom of the pull rod section, and then the core mold is installed on the press; S3, roll forming: the support frame is provided with two installation grooves arranged in upper and lower rows, the first-pass and second-pass roll molds are first installed in the two installation grooves respectively, then the preheated blank is sleeved into the core mold, the core mold is driven to move downward by the press, the core mold drives the blank to pass through the roll forming cavities of the first-pass and second-pass roll molds in sequence, and the first-pass and second-pass roll forming is completed; then the core mold is driven to move upward, the cylindrical part is withdrawn from the support frame along with the core mold, the first-pass and second-pass roll molds are removed, the third-pass and fourth-pass roll molds are installed in the two installation grooves respectively, the core mold is driven to move downward, the core mold drives the blank to pass through the roll forming cavities of the third-pass and fourth-pass roll molds in sequence, and the third-pass and fourth-pass roll forming is completed, that is, the core mold drives the blank to pass through the roll forming cavities of all the roll molds in sequence, so that the plurality of rollers on the roll molds are passively rotated at the same speed towards the center of the roll forming cavity to roll the blank, the pass compression rate of the roll mold is 8%-35%, the wall thickness of the blank is reduced and formed into a cylindrical part, and the multi-pass roll forming of the blank is completed; after the roll forming, the disc is located on the inside of the top of the cylindrical part; S4, flanging: the core mold is driven to move upward, the cylindrical part is withdrawn from the support frame along with the core mold, then the roll molds on the support frame are removed, then the core mold is removed, an annular flanging disc is installed on the core mold, the diameter of the flanging disc gradually decreases from top to bottom, and the peripheral side surface of the flanging disc is an inwardly concave arc surface, the bottom of the flanging disc is inserted between the top of the cylindrical part and the core mold, before the flanging disc is installed, the disc is first removed from the core mold, so that a space is left between the top of the cylindrical part and the pull rod section for the bottom of the flanging disc to be inserted; then the core mold is placed in the support frame, a backing plate is installed in the interior of the support frame to support the core mold and the cylindrical part, then the flanging disc is pressed downward by the press, so that the top part of the cylindrical part is flanged along the peripheral side surface of the flanging disc, and the flanging is formed. S5, demolding: after the completion of the flanging, drive the press up, remove the flanging disc, put the blocking plate into the core mold, and fix the blocking plate and the support frame, the lower end surface of the blocking plate is in contact with the top flange of the cylindrical part, then install the core mold on the press, drive the core mold up to pull out the core mold from the cylindrical part, in this process, the cylindrical part will be pushed up, the blocking plate prevents the cylindrical part from moving axially while providing a reverse support point, so that the demolding force is converted from pure friction to structural limiting force, and the flange and the blocking plate are in contact, which increases the tendency of the cylindrical part and the core mold to separate, and also forms a ring-shaped reinforcing rib structure on the edge of the cylindrical part, which strengthens the cylinder structure of the cylindrical part and disperses stress; then disassemble the blocking plate and take out the cylindrical part from the support frame.

2. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 1, characterized in that: In step S2, the upper and lower two adjacent roll dies are arranged in a row, and the central axis of the upper roller and the central axis of the lower roller are distributed at a certain angle.

3. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 2, characterized in that: In steps S2-S3, the pass compression rates of the first pass roll die, the second pass roll die, the third pass roll die, and the fourth pass roll die are 25%-35%, 20%-28%, 15-25%, and 8%-23%, respectively.

4. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 3, characterized in that: In steps S2-S3, four rollers are arranged in each pass roll die, and the central axes of the first and third pass rollers are distributed at an angle of 45° with the central axes of the second and fourth pass rollers.

5. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 1, characterized in that: In steps S2-S3, the roll die is a box-shaped structure, and the middle part of the roll die is provided with an installation cavity penetrating upward and downward and used for installing rollers, the support frame is a rectangular frame, the inside of the support frame is hollow, and the inner side wall is provided with an installation slot used for installing the roll die, one side wall of the support frame is provided with a square installation opening in communication with the installation slot, and the roll die is inserted into or extracted from the installation slot through the installation opening.

6. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 1, characterized in that: In steps S2-S5, the lower part of the press is fixed with an upper die plate, the lower part of the upper die plate is fixed with an upper die plate backing plate, the top of the pull rod section of the core mold is detachably installed on the bottom of the upper die plate backing plate through a fixed pin, and the core mold is disassembled by removing the pull rod section from the upper die plate backing plate; an annular backing plate is placed on the flanging disc, and the upper die plate backing plate is driven downward by the press to drive the flanging disc downward.

7. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 1, characterized in that: In step S5, the middle part of the blocking plate is provided with a through hole for the core mold to pass through, and the blocking plate is sleeved on the pull rod section through the through hole, and the core mold has a core mold extraction slope of 0.8°.

8. A method of hydrostatic extrusion of a large aspect ratio cylindrical part as claimed in claim 1, characterized in that: In step S5, the top of the support frame is provided with a circular opening in communication with the inside, the core mold and the cylindrical part enter the support frame from the circular opening, the outer periphery of the circular opening is provided with a bolt mounting hole for fixing the blocking plate and the support frame by bolts, and the bottom of the support frame is provided with an ejection rod, which pushes the cylindrical part out of the support frame after the blocking plate is disassembled, and then the flange and other size allowances of the cylindrical part are trimmed to make the size of the cylindrical part meet the design requirements, and then the cylindrical part is subjected to solid solution and aging treatment.

9. A large aspect ratio tubular roll forming die for use in the method of any one of claims 1 to 8, characterized by: The application relates to a roll drawing forming die which comprises a support frame, a core mold and a plurality of roll molds, the plurality of roll molds are detachably arranged on the support frame in a vertical direction, each roll mold is a one-pass extrusion process, a plurality of rollers are arranged in the roll mold, the rolling surface of the roller is an inner concave arc surface, the plurality of rollers are distributed in a circumferential direction to form a cylindrical roll drawing cavity, the diameter of the roll drawing cavity is smaller than the diameter of a blank, the diameter of the roll drawing cavity of the plurality of roll molds decreases from top to bottom, the center of the roll drawing cavity of the plurality of roll molds and the center of the core mold are on the same axis, four rollers are arranged in each roll mold, the central axes of the rollers in the first and third passes are distributed at an angle of 45 DEG with the central axes of the rollers in the second and fourth passes, the roll mold is a box-shaped structure, a mounting cavity for mounting the rollers is arranged in the middle of the roll mold and penetrates the roll mold in a vertical direction, the support frame is a rectangular frame, the inside of the support frame is hollow, and an installation groove for mounting the roll mold is arranged on the inner side wall of the support frame, a square installation opening which is in communication with the installation groove is arranged on one side wall of the support frame, and the roll mold is inserted into or taken out of the installation groove through the installation opening. The upper part of the core mold is provided with a pull rod section with a diameter smaller than the middle part and the lower part of the core mold, a disc is arranged on the bottom of the pull rod section, an annular flanging disc is arranged on the core mold, the diameter of the flanging disc decreases from top to bottom, and the circumferential surface of the flanging disc is an inner concave arc surface, the bottom of the flanging disc is inserted between the top of the cylindrical part and the core mold, and the disc is taken off from the core mold before the flanging disc is arranged, so that a space is left between the top of the cylindrical part and the pull rod section for inserting the bottom of the flanging disc. The core mold is arranged on a press, an upper die plate is fixed below the press, an upper die plate backing plate is fixed below the upper die plate, the top of the pull rod section of the core mold is detachably arranged on the bottom of the upper die plate backing plate through a fixing pin, the core mold is taken off by taking off the pull rod section from the upper die plate backing plate, an annular backing plate is arranged on the flanging disc, the upper die plate backing plate is driven downward by the press to drive the flanging disc to move downward. The roll drawing forming die further comprises a material blocking plate which is sleeved on the core mold, a through hole is arranged in the middle of the material blocking plate for the core mold to pass through, the material blocking plate is sleeved on the pull rod section through the through hole, and the material blocking plate is fixed with the support frame, screw mounting holes are arranged on the outer periphery of the circular opening at the top of the support frame, and the material blocking plate is fixed with the support frame through the screws, screw holes which are matched with lifting ring bolts are arranged on the disc, the flanging disc and the material blocking plate, and the disc, the flanging disc and the material blocking plate are moved and disassembled through the lifting ring bolts. A circular opening which is in communication with the inside of the support frame is arranged at the top of the support frame, the core mold and the cylindrical part enter the support frame from the circular opening, and screw mounting holes are arranged on the outer periphery of the circular opening to fix the material blocking plate with the support frame through the screws.

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