Transition die and method for necking down large aspect ratio thin-walled annular parts

Abstract

The application discloses a necking forming transition die and a necking forming method for a large-expansion-ratio thin-wall annular part. The necking forming transition die realizes the rotation of a rotating forming block pushed by a side pushing block through a lever principle to apply a necking forming force, so that the necking forming force is uniformly dispersed on an inner circular arc generatrix of a part wave trough, a force application position is changed from a point to a line, a bearing area is increased, a deformation stress is reduced, stress concentration in a necking process is eliminated, a material thinning degree during necking is reduced, material thinning uniformity is improved, necking cracks at an inner fillet of a wave-shaped edge are prevented, a material forming limit is improved, a part forming expansion ratio is improved, and the necking forming of the large-expansion-ratio thin-wall annular part can be well applied. Meanwhile, during the rotating forming process, there is basically no relative movement between the rotating forming block and a part outer shape surface, surface scratches of the part are avoided, and the part surface quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sheet metal forming, in particular, to a closing forming transition die and closing forming method for a large-expansion-ratio thin-walled annular part. BACKGROUND

[0002] As shown in Figures 1 to 3 , the circumferential wave-shaped end face of the large-expansion-ratio thin-walled annular part has a length-to-circumference ratio (expansion ratio) of 2 or more, and the profile of the wave-shaped section fluctuates sharply. The blank is usually formed by a radial side-pushing method, and the side-pushing closing die used is shown in Figure 4 . The die closing forming process is as follows: the upper die plate 200 drives the wedge 300 to move downward, and the wedge 300 pushes the side-pushing punch 100 to move radially on the positioning outer ring 400 during the downward movement of the wedge 300. The outer profile of the wave-shaped section is extruded by the side-pushing punch 100 to realize the stamping forming of the wave-shaped section. The specific structure of the side-pushing closing die is shown in the patent CN202110318098.5 previously applied by the applicant. However, in the side-pushing forming process, the force application part of the die closing is always the fillet part of the side-pushing punch, the contact mode between the side-pushing punch and the wave-shaped section is point contact, the contact area is small, stress is concentrated, the inner fillet of the wave-shaped edge is seriously thinned after forming and is prone to cracking, and the contact surface is prone to scratches. At the same time, before the die is attached to the mold, the outer surface of the transition part of the conical surface is not constrained, and under the action of the downward force of the profile conical surface stretching, the material at the transition part of the profile and the conical surface is prone to instability and bulging downward and outward. Especially, the larger the circumferential expansion ratio of the part is, the higher the wave-shaped height is, and the more prone the inner fillet of the wave-shaped edge is to thinning and cracking after forming, and the more serious the material instability and bulging at the transition part of the part conical surface are, which seriously affects the profile precision of the part. SUMMARY

[0003] The present application provides a closing forming transition die and closing forming method for a large-expansion-ratio thin-walled annular part to solve the technical problem of thinning and cracking of the inner fillet of the wave-shaped edge after forming caused by the existing side-pushing closing die.

[0004] According to one aspect of the present application, a necking forming transition die for a large-expansion-ratio thin-wall annular part is provided, comprising a lower die plate, a positioning outer ring, a wedge block, a side push block, a rotary forming block, a combined core block, a support ring and an upper die plate, the positioning outer ring is fixedly installed on the lower die plate, the upper die plate is installed on a machine tool, the wedge block and the support ring are installed on the upper die plate, the side push block is radially slidably connected with the positioning outer ring, the combined core block is radially slidably connected with the lower die plate, the rotary forming block is rotatably supported on the side push block, by pressing down the upper die plate, the combined core block is moved radially outward under the extrusion of the support ring and tightly supports the inner profile of the cylindrical section of the part, the side push block is synchronously moved radially inward under the extrusion of the wedge block and pushes the rotary forming block to rotate around the supporting point, the rotary forming block extrudes the outer profile of the wave-shaped section of the part during the rotation, thereby realizing the wave-shaped inward collection of the wave-shaped section of the part through the extrusion cooperation of the combined core block and the rotary forming block.

[0005] Further, the side push block comprises a sliding part, a slope part and a supporting part, a guide groove is radially formed on the positioning outer ring, the sliding part is installed in the guide groove, the wedge block is pressed against the slope part, the rotary forming block is rotatably supported on the supporting part, the sliding part, the slope part and the supporting part are integrally formed or fixedly connected as a whole after being separately manufactured.

[0006] Further, an angular positioning groove is formed on the supporting part, before necking forming, the rotary forming block is hung on the angular positioning groove.

[0007] Further, the height of the supporting surface on the supporting part is 1 / 3-3 / 4 of the length of the generatrix of the wave-shaped section of the part.

[0008] Further, the height of the supporting surface on the supporting part is 2 / 3 of the length of the generatrix of the wave-shaped section of the part.

[0009] Further, the rotary forming block comprises an angular positioning section and a rotary supporting section which are connected in series, the thickness of the angular positioning section is greater than that of the rotary supporting section, before necking forming, the angular positioning section is hung on the angular positioning groove, at this time, the rotary supporting section is in a vertical suspended state and is in contact with the part, during necking forming, the rotary forming block is arcually rotated around the rotary supporting point on the supporting part until it is tightly supported on the supporting surface of the supporting part.

[0010] Further, the thickness of the rotary supporting section is 9mm-15mm.

[0011] Further, at the initial forming position, the bottom end of the rotary supporting section is lower than the wave-shaped root of the wave-shaped section of the part and a gap is reserved between the rotary supporting section and the positioning outer ring.

[0012] Further, the working profile of the rotating forming block is cylindrical.

[0013] In addition, the application also provides a necking forming method for a large-expansion-ratio thin-wall annular part, which adopts the necking forming transition die described above and comprises the following contents.

[0014] The part is placed into the positioning outer ring, the combined core block is placed into the sliding groove of the lower die plate and adjusted to be symmetrical and integral, the rotating forming block is supported on the side pushing block, and after the part blank profile is angularly aligned with the rotating forming block, the side pushing block is manually pushed to make the rotating forming block closely contact with the part blank profile;

[0015] The machine is started to be pressed down, the combined core block is moved outward along the radial direction under the extrusion of the supporting ring and extrudes the inner profile of the part wave-shaped section, the side pushing block is synchronously moved inward along the radial direction under the extrusion of the wedge block and pushes the rotating forming block to rotate around the supporting point, and the rotating forming block extrudes the outer profile of the part wave-shaped section in the rotating process, so that the wave-shaped inward collection of the part wave-shaped section is realized through the extrusion cooperation of the combined core block and the rotating forming block.

[0016] The part is heat treated to eliminate hardening, and is shaped by the side pushing necking die to meet the final size requirements of the part.

[0017] The application has the following effects:

[0018] The necking forming transition die for a large-expansion-ratio thin-wall annular part provided by the application drives the upper die plate, the supporting ring and the wedge block to move downward as a whole through the pressing down of the machine, so that the combined core block is moved outward along the radial direction under the extrusion of the supporting ring and tightly supports the inner profile of the part cylindrical section, and the side pushing block is synchronously moved inward along the radial direction under the extrusion of the wedge block and pushes the rotating forming block to rotate around the supporting point, and the rotating forming block extrudes the outer profile of the part wave-shaped section in the rotating process, so that the wave-shaped inward collection of the part wave-shaped section is realized through the extrusion cooperation of the combined core block and the rotating forming block. The application improves the side pushing point contact forming mode of the existing side pushing necking die into a side pushing rotating line contact forming mode, realizes the rotation of the rotating forming block pushed by the side pushing block through the lever principle to apply the necking forming force, makes the necking forming force uniformly dispersed on the inner circular arc generatrix of the part wave trough, changes the force application position from a point to a line, increases the bearing area, reduces the deformation stress, eliminates the stress concentration in the necking process, reduces the material thinning degree during necking, improves the material thinning uniformity, prevents the necking cracks from occurring at the inner circular corner of the wave-shaped edge, improves the material forming limit, improves the expansion ratio of the part forming, and can be well applied to the necking forming of a large-expansion-ratio thin-wall annular part. Meanwhile, there is basically no relative movement between the rotating forming block and the part outer profile in the rotating forming process, avoids the scratching of the part surface, and improves the part surface quality.

[0019] In addition, the large-expansion-ratio thin-wall ring part necking forming method of the present application first adopts a necking forming transition die to perform rough necking on the outer surface of the part, realizes integral forming of the main dimensions of the outer surface of the part, and then performs shaping and sizing by a side pushing necking die to meet the design surface dimension requirements. The necking forming transition process is added between the part blank and the necking forming, compared with the existing mode of directly necking the blank by the side pushing necking die, the deformation stress is reduced, the stress concentration in the necking process is eliminated, the material thinning degree during necking is reduced, the material thinning uniformity is improved, the necking cracks at the wave-shaped edge inner corner are prevented, the material forming limit is improved, the expansion ratio of the part forming is improved, and the necking forming of the large-expansion-ratio thin-wall ring part can be well applied, while the part surface scratch is avoided and the part surface quality is improved.

[0020] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the application, and are incorporated herein for purposes of illustrating the illustrative embodiments of the present application and the explanations provided herein. In the drawings:

[0022] Figure 1 is a top view structural schematic diagram of a large-expansion-ratio thin-wall ring part.

[0023] Figure 2 is a side view structural schematic diagram of a large-expansion-ratio thin-wall ring part.

[0024] Figure 3 is a schematic diagram of the existing radial side pushing forming mode for necking forming of a large-expansion-ratio thin-wall ring part.

[0025] Figure 4 is a partial cross-sectional structural schematic diagram of an existing side pushing necking die.

[0026] Figure 5 is a cross-sectional structural schematic diagram of a necking forming transition die of a large-expansion-ratio thin-wall ring part of a preferred embodiment of the present application.

[0027] Figure 6 is a schematic diagram of necking forming of a part by a rotating forming block under the side pushing action of a side pushing block according to the preferred embodiment of the present application.

[0028] Figure 7 is a cross-sectional structural schematic diagram of a side pushing block according to the preferred embodiment of the present application.

[0029] Figure 8is a schematic view of the top structure of the side push block of the preferred embodiment of the present application.

[0030] Figure 9 is a schematic view of the front structure of the rotary forming block of the preferred embodiment of the present application.

[0031] Figure 10 is a schematic view of the top structure of the rotary forming block of the preferred embodiment of the present application.

[0032] Figure 11 is a schematic view of the structure of the positioning of the blank in the necking forming transition die before necking forming of the preferred embodiment of the present application.

[0033] Figure 12 is a schematic view of the necking forming of the part by the necking forming transition die of the large-expansion-ratio thin-walled ring-shaped part of the preferred embodiment of the present application.

[0034] Explanation of Reference Signs

[0035] 100, side push punch; 300, wedge; 1, lower die plate; 400, 2, positioning outer ring; 3, wedge block; 4, side push block; 5, rotary forming block; 6, combined core block; 7, support ring; 200, 8, upper die plate; 41, sliding portion; 42, slope portion; 43, abutting portion; 44, angular positioning groove; 45, abutting surface; 51, angular positioning section; 52, rotary abutting section. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following.

[0037] As Figures 5 to 12As shown, the preferred embodiment of the present application provides a necking forming transition die for a large-expansion-ratio thin-walled annular part, which comprises a lower die plate 1, a positioning outer ring 2, a wedge block 3, a side push block 4, a rotating forming block 5, a combined core block 6, a support ring 7, and an upper die plate 8, the positioning outer ring 2 is fixedly installed on the lower die plate 1, the upper die plate 8 is installed on a machine tool, the wedge block 3 and the support ring 7 are installed on the upper die plate 8, the side push block 4 is in radial sliding connection with the positioning outer ring 2, the combined core block 6 is in radial sliding connection with the lower die plate 1, the rotating forming block 5 is rotatably supported on the side push block 4, by the pressing of the upper die plate 8, the combined core block 6 moves outward along the radial direction under the extrusion of the support ring 7 and supports the inner profile of the cylindrical section of the part, the side push block 4 moves inward along the radial direction under the extrusion of the wedge block 3 and pushes the rotating forming block 5 to rotate around the supporting point, and the rotating forming block 5 extrudes the outer profile of the wave-shaped section of the part during rotation, so that the wave-shaped inward collection of the wave-shaped section of the part is realized through the extrusion cooperation of the combined core block 6 and the rotating forming block 5. It can be understood that the large-expansion-ratio thin-walled annular part comprises a wave-shaped section and a cylindrical section in the shape of a cone, during necking forming, the combined core block 6 is located on the inner side of the part, the positioning outer ring 2 and the side push block 4 are located on the outer side of the part, during the pressing of the upper die plate 8, the combined core block 6 first supports the inner profile of the cylindrical section, and the positioning outer ring 2 is attached to the outer profile of the cylindrical section, so that the cylindrical section is clamped and positioned through the positioning outer ring 2 and the combined core block 6, so as to realize the positioning of the entire part, and at the same time, the inward pushing and turning of the side push block 4 and the rotating forming block 5 makes the inner profile of the wave-shaped section slowly attach to the combined core block 6, at this time, the combined core block 6 supports the inner profiles of the cylindrical section and the wave-shaped section, and then realizes necking forming under the support of the combined core block 6 and the inward pushing and turning of the side push block 4 and the rotating forming block 5. Among them, the number of the wedge block 3, the side push block 4 and the rotating forming block 5 is equal to and corresponds to the number of wave valleys of the wave-shaped section of the part. In addition, the specific structure and specific connection relationship of the lower die plate 1, the positioning outer ring 2, the wedge block 3, the combined core block 6, the support ring 7, and the upper die plate 8 belong to the prior art, and specific reference is made to patent application CN202110318098.5.

[0038] It can be understood that the large expansion ratio thin-walled annular part closing forming transition die of the embodiment is driven by the machine tool to move the upper die plate 8, the support ring 7 and the wedge block 3 downward as a whole, so that the combined core block 6 moves outward along the radial direction under the extrusion and support of the support ring 7 and tightens the inner profile of the cylindrical section of the part, and at the same time, the side pushing block 4 moves inward along the radial direction under the extrusion of the wedge block 3 and pushes the rotating forming block 5 to rotate around the supporting point, the rotating forming block 5 extrudes the outer profile of the wave-shaped section of the part during the rotation, and the wave-shaped section of the part is formed by the extrusion of the combined core block 6 and the rotating forming block 5, so that the main dimension of the outer profile of the part is formed as a whole, and then the side pushing closing die is used for shaping and sizing to meet the design profile size requirement. The side pushing point contact forming mode of the existing side pushing closing die is improved to the side pushing rotating line contact forming mode, the lever principle is used to push the rotating forming block 5 to rotate by the side pushing block 4 to apply the closing forming force, the closing forming force is uniformly dispersed on the inner circular arc generatrix of the wave valley of the part, the force application position is changed from point to line, the bearing area is increased, the deformation stress is reduced, the stress concentration in the closing process is eliminated, the material thinning degree during closing is reduced, the material thinning uniformity is improved, the closing cracks at the inner round corners of the wave-shaped edge are prevented, the forming limit of the material is improved, the expansion ratio of the part forming is improved, and the closing forming of the large expansion ratio thin-walled annular part is well applicable.

[0039] Specifically, the side pushing block 4 includes a sliding part 41, a slope part 42 and a supporting part 43, a guide groove is formed on the positioning outer ring 2 along the radial direction, the sliding part 41 is installed in the guide groove, the wedge block 3 is pressed against the slope part 42, and the rotating forming block 5 is rotatably supported on the supporting part 43, and the sliding part 41, the slope part 42 and the supporting part 43 are integrally formed or fixedly connected as a whole after being manufactured in parts. During the closing forming process, the pressing force of the wedge block 3 is applied to the slope surface of the slope part 42, so as to convert the pressing force into the side pushing force, and then push the whole side pushing block 4 to move inward along the radial direction on the guide groove of the positioning outer ring 2, and push the rotating forming block 5 to rotate around the rotating supporting point until the rotating forming block 5 is closely pressed against the supporting surface 45 of the supporting part 43, the rotating forming block 5 rotates clockwise, and the working profile of the rotating forming block 5 extrudes and forms the wave valley of the part during the rotation of the rotating forming block 5.

[0040] Optionally, an angular positioning groove 44 is formed on the abutting part 43, and the rotating forming block 5 is hung in the angular positioning groove 44 before the closing forming. The angular positioning groove 44 angularly positions the rotating forming block 5 before the closing forming, ensures the angular positioning accuracy between the rotating forming block 5 and the part valley, and ensures the forming precision of the part outer surface. The width of the angular positioning groove 44 is 18 mm, and the depth is 5 mm.

[0041] Optionally, the height H of the abutting surface 45 determines the force application position during the closing forming. Since the material overturning fulcrum during the closing is at the transition between the wave-shaped section and the cylindrical section, the greater the H, the closer the force application point to the wave-shaped top. Based on the lever principle, the required closing force is smaller, the pressure applied by the rotating forming block 5 to the transition is smaller, and the transition is more prone to downward bulging instability, thereby affecting the part surface precision. The smaller the H, the closer the force application point to the wave-shaped bottom, and the greater the required closing force. The pressure applied by the rotating forming block 5 to the transition is greater, which is beneficial to prevent the transition from downward bulging instability, but if the H is too small and the closing force is too large, the side pushing block 4 and the rotating forming block 5 are prone to damage or even unable to be pushed sideways (because the equipment tonnage may not be enough). Therefore, from the perspective of considering the side pushing force and reducing the risk of instability bulging at the transition, the height H of the abutting surface 45 is controlled to be 1 / 3-3 / 4 of the length of the part wave-shaped section generatrix. As a preferred, the height of the abutting surface 45 is 2 / 3 of the length of the part wave-shaped section generatrix, that is, the upper end of the abutting surface 45 corresponds to the 2 / 3 of the length of the part wave-shaped section generatrix from bottom to top.

[0042] Specifically, the rotating forming block 5 includes an angular positioning section 51 and a rotating abutting section 52 connected in sequence, the thickness of the angular positioning section 51 is greater than that of the rotating abutting section 52, and the angular positioning section 51 is hung in the angular positioning groove 44 before the closing forming. At this time, the rotating abutting section 52 is in a vertically suspended state and in contact with the part, and in the process of the closing forming, the rotating forming block 5 rotates clockwise around the rotating fulcrum on the abutting part 43 until it abuts against the abutting surface 45 of the abutting part 43. The rotating fulcrum on the abutting part 43 is designed as a curved surface, and the connection between the angular positioning section 51 and the rotating abutting section 52 is designed with a round corner transition to ensure the smoothness of rotation.

[0043] Optionally, in the initial forming position, the bottom end of the rotating abutting section 52 should be lower than the wave-shaped root of the part wave-shaped section and maintain a gap with the positioning outer ring 2, which ensures that the rotating abutting section 52 can constrain the transition before the closing forming, prevents the transition between the wave-shaped section and the cylindrical section from outward bulging instability during the closing forming, and prevents the rotating forming block 5 from interfering with the top of the positioning outer ring 2 during the rotation.

[0044] It can be understood that the thickness L of the rotating supporting section 52 should be as small as possible under the premise of ensuring strength, because at the beginning of the side pushing, the angle between the line connecting the supporting points A and B of the rotating forming block 5 and the side pushing direction is greater than 90°, the greater the thickness L of the rotating supporting section 52, the greater the angle, the greater the downward side pushing force, and the greater the downward sliding amount of the rotating forming block 5, which is not conducive to preventing the instability protrusion at the transition. Therefore, as preferred, the thickness of the rotating supporting section 52 is 9mm-15mm, and further preferably 10mm.

[0045] Optionally, the working profile of the rotating forming block 5 is cylindrical. The machining size of the cylindrical shape is not only easy to ensure, but also reduces the machining difficulty and cost, and the stress state of the part is stable and unchanged during the closing forming process, and the forming stability is good. If the working profile of the rotating forming block 5 is designed to be consistent with the outer profile of the part, since the supporting point positions of the working profile of the rotating forming block 5 and the outer profile of the part are constantly changing during the rotating forming process, the working profile cannot always be in close contact with the outer profile of the part, and the profile forming precision is difficult to guarantee. It can be understood that the working profile of the cylindrical shape naturally transitions with the outer profile of the part, thereby realizing the overall forming of the main size of the outer profile of the part, realizing rough closing, and after solid solution stress relief, reshaping and shaping are performed by the existing side pushing closing die to meet the design profile size requirements.

[0046] It can be understood that the present application has also been verified in practice, Figure 1 The wave-shaped root of the part has a circumference of 1281.2mm, the unfolded circumference of the large end before the blank closing is 2895.47mm, and the unfolded circumference of the large end after the closing by the closing forming transition die of the present application is 2983.94mm, the circumference after the closing increases by 88.47mm, the average elongation rate after the closing is about 3.1%, that is, the blank will be thinned to a certain extent after the deformation, and the total length ratio is 2.33. After multiple verifications, the maximum thinning rate after the closing by the closing forming transition die of the present application is less than 10%, while the maximum thinning rate of the wave-shaped top blank due to stress concentration after the closing by the existing closing method is more than 20%, so it can be seen that the closing forming transition die of the present application greatly improves the deformation condition of the blank and improves the forming limit after the closing.

[0047] In addition, another embodiment of the present application also provides a closing forming method for a large-length-ratio thin-walled annular part, preferably using the closing forming transition die as described above, including the following contents:

[0048] Step S1: placing the part into the positioning outer ring 2, then placing the combined core block 6 in the sliding groove of the lower die plate 1 and adjusting it to be symmetrical and integral, supporting the rotating forming block 5 on the side pushing block 4, and after the part blank profile is angularly aligned with the rotating forming block 5, pushing the side pushing block 4 by hand to make the rotating forming block 5 closely contact with the part blank profile;

[0049] Step S2: Start the machine to press down, make the combined core block 6 move outward along the radial direction under the extrusion of the support ring 7 and support the inner profile of the part cylindrical section, make the side push block 4 move inward along the radial direction under the extrusion of the wedge block 3 and push the rotary forming block 5 to rotate around the supporting point, and the rotary forming block 5 extrudes the outer profile of the part wave-shaped section during the rotation, so that the wave-shaped inward retraction of the part wave-shaped section is realized through the extrusion cooperation of the combined core block 6 and the rotary forming block 5.

[0050] Step S3: Heat treatment is performed on the part to eliminate hardening, and the side push closing die is used for shaping to meet the final size requirements of the part.

[0051] Specifically, after the positioning outer ring 2 is fixedly installed on the lower die plate 1, the part is placed in the positioning outer ring 2, the outer profile of the part cylindrical section is attached to the positioning outer ring 2, then the combined core block 6 is placed in the radial sliding groove of the lower die plate 1 and adjusted to be symmetrical and integral, then the rotary forming block 5 is placed in the angular positioning groove 44 of the side push block 4 and closely attached, the angular position of the part closing blank is adjusted, the blank profile is angularly aligned with the rotary forming block 5, and then each side push block 4 is manually pushed to closely attach the rotary forming block 5 to the part blank, thereby completing the preliminary positioning of the part.

[0052] After the part is positioned, the machine is started to press down to drive the upper die plate 8, the support ring 7 and the wedge block 3 to move downward as a whole, so that the combined core block 6 moves outward along the radial direction under the extrusion of the support ring 7 and supports the inner profile of the cylindrical section, the part cylindrical section is clamped and positioned through the inner and outer extrusion of the combined core block 6 and the positioning outer ring 2, thereby realizing the positioning of the entire part. At the same time, the side push block 4 moves inward along the radial direction under the extrusion of the wedge block 3 and pushes the rotary forming block 5 to rotate around the supporting point, the rotary forming block 5 extrudes the outer profile of the part wave-shaped section during the rotation, so that the inner profile of the wave-shaped section is slowly attached to the combined core block 6, at this time, the combined core block 6 supports the inner profiles of the cylindrical section and the wave-shaped section, then the inward pushing, turning and supporting of the combined core block 6 are realized under the inward pushing, turning and supporting of the combined core block 6.

[0053] After the waveform inward collection is completed, the overall shaping of the main size of the outer surface of the part is realized, but the forming precision of the outer surface at this time cannot meet the size requirements. After heat treatment of the part to eliminate hardening, i.e. stress, the side push block 4 and the rotating forming block 5 are replaced with the existing side push punch, and the existing side push closing die is used again for closing forming, i.e. finishing the rough surface formed after the closing forming transition die, to meet the final size requirements of the part. Therefore, the closing forming transition die of the present application can also share part of the existing side push closing die, greatly reducing the development difficulty and manufacturing cost of the die. The specific structure of the side push closing die belongs to the prior art, and specific reference is made to patent CN202110318098.5, so it is not repeated here.

[0054] It can be understood that the closing forming method of the large expansion ratio thin-walled annular part in the embodiment first coarsely closes the outer surface of the part by using the closing forming transition die of the above-mentioned embodiment, realizes the overall shaping of the main size of the outer surface of the part, and then shapes and corrects the part by the side push closing die to meet the design surface size requirements, completes the fine closing, and increases the closing forming transition process between the part blank and the closing forming. Compared with the existing way of directly closing forming the blank by the side push closing die, the deformation stress is reduced, the stress concentration in the closing process is eliminated, the material thinning degree during closing is reduced, the material thinning uniformity is improved, the closing cracks at the waveform edge inner corner are prevented, and the material forming limit is improved, the expansion ratio of the part forming is improved, and the closing forming of the large expansion ratio thin-walled annular part can be well applied, while avoiding the surface scratch of the part and improving the surface quality of the part.

[0055] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A necking transition die for the forming of large spread ratio thin walled annular parts, characterized by, The assembly includes a lower template (1), a positioning outer ring (2), a wedge block (3), a side push block (4), a rotating forming block (5), a combined core block (6), a support ring (7), and an upper template (8). The positioning outer ring (2) is fixedly installed on the lower template (1), the upper template (8) is installed on a machine tool, the wedge block (3) and the support ring (7) are installed on the upper template (8), the side push block (4) is radially slidably connected to the positioning outer ring (2), the combined core block (6) is radially slidably connected to the lower template (1), and the rotating forming block (5) is rotatable. The part is supported on the side push block (4). The upper template (8) presses down, causing the combined core block (6) to move radially outward under the squeezing action of the support ring (7) and tighten the inner surface of the cylindrical section of the part. The side push block (4) moves radially inward synchronously under the squeezing action of the wedge block (3) and pushes the rotating forming block (5) to rotate around the support point. During the rotation, the rotating forming block (5) squeezes the outer surface of the waveform section of the part, thereby achieving the inward contraction of the waveform section of the part through the squeezing cooperation of the combined core block (6) and the rotating forming block (5).

2. The necking transition die for large-draw-ratio thin-wall ring parts according to claim 1, wherein The side push block (4) includes a sliding part (41), a ramp part (42) and a support part (43). A guide groove is provided radially on the positioning outer ring (2). The sliding part (41) is installed in the guide groove. The wedge block (3) presses against the ramp part (42). The rotating forming block (5) is rotatably supported on the support part (43). The sliding part (41), the ramp part (42) and the support part (43) are integrally formed or are manufactured separately and then fixedly connected as a whole.

3. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 2, wherein, The support part (43) is provided with an angular positioning groove (44). Before the end forming is performed, the rotating forming block (5) is attached to the angular positioning groove (44).

4. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 2, wherein, The height of the support surface (45) on the support part (43) is 1 / 3 to 3 / 4 of the length of the busbar of the waveform segment of the part.

5. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 2, wherein, The height of the support surface (45) on the support part (43) is 2 / 3 of the length of the busbar of the waveform segment of the part.

6. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 3, wherein, The rotating forming block (5) includes an angular positioning section (51) and a rotating support section (52) connected vertically. The thickness of the angular positioning section (51) is greater than that of the rotating support section (52). Before the closing forming is performed, the angular positioning section (51) is attached to the angular positioning groove (44). At this time, the rotating support section (52) is in a vertically suspended state and in contact with the part. During the closing forming process, the rotating forming block (5) rotates around the rotating fulcrum arc surface on the support part (43) until it is pressed against the support surface (45) of the support part (43).

7. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 6, wherein, The thickness of the rotating support section (52) is 9mm to 15mm.

8. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 6, wherein, At the initial forming position, the bottom end of the rotating support section (52) is lower than the root of the waveform of the part waveform section and a gap is maintained between it and the positioning outer ring (2).

9. The necking transition die for large-draw-ratio thin-wall ring part forming according to claim 6, wherein, The working surface of the rotating forming block (5) is cylindrical.

10. A method of necking forming a large spread ratio thin-walled ring member using the necking forming transition die according to any one of claims 1 to 9, characterized by, Includes the following: Put the part into the positioning outer ring (2), then put the combined core block (6) into the sliding groove of the lower die plate (1) and adjust to the symmetrical whole ring, put the rotary forming block (5) on the side push block (4), and after the part blank profile is angularly aligned with the rotary forming block (5), push the side push block (4) by hand, so that the rotary forming block (5) is closely attached to the part blank profile; Start the machine to press down, so that the combined core block (6) moves outward along the radial direction under the extrusion of the supporting ring (7) and tightly supports the inner profile of the part cylindrical section, so that the side push block (4) moves inward along the radial direction under the extrusion of the inclined wedge block (3) and pushes the rotary forming block (5) to rotate around the supporting point, and the rotary forming block (5) extrudes the outer profile of the part wave section during the rotation, so that the wave inward convergence of the part wave section is realized through the extrusion cooperation of the combined core block (6) and the rotary forming block (5); Heat treatment is performed on the part to eliminate hardening, and the side push closing die is used for shaping to meet the final size requirements of the part.

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