A breakage-proof press forming die

Abstract

The present application relates to the technical field of intelligent manufacturing equipment industry, and particularly relates to a stamping forming die capable of preventing breakage, which comprises a rack, an upper die assembly and a lower die assembly, the rack is provided with an upper mounting plate and a lower mounting plate; the upper die assembly comprises a punch, a pressing ring and a suction pipe; the punch is arranged on the upper mounting plate, and the lower end of the punch is provided with a suction passage; the pressing ring is coaxially arranged outside the punch, and the suction pipe is coaxially arranged in the punch; the lower die assembly comprises an annular seat and a concave die; the annular seat is arranged on the lower mounting plate, the concave die is arranged in the annular seat, and the inside of the concave die is provided with a cavity; when the upper die assembly approaches the lower die assembly and performs stamping on a blank to be processed, the punch can be inserted into the cavity and draw the center part of the blank to be processed into a cylindrical part, at the same time, the punch can be lowered relative to the suction pipe, so that the suction passage is communicated with the suction pipe, so that the inner wall of the cylindrical part is attached to the outer circumferential surface of the punch, thereby avoiding breakage of the cylindrical part and improving the stamping forming quality.

Description

Technical Field

[0001] This invention relates to the field of intelligent manufacturing equipment technology, and in particular to a fracture-resistant stamping die. Background Technology

[0002] Stamping is the mainstream processing technology for producing thin-walled metal parts. It covers complex forming structures such as ordinary bending, flanging, punching and deep drawing. For cylindrical, box-shaped and various irregular deep cavity parts, it is usually equipped with special stamping forming dies to carry out large-scale operations. Patent document CN121446914B discloses a stamping die for irregularly shaped parts and its method of use. The stamping die includes an upper die assembly, a lower die assembly, and a graded drive mechanism. The upper die assembly includes at least two coaxially arranged forming units, each forming unit including a punch and at least one sleeve sleeved outside the punch. The graded drive mechanism is connected to the upper die assembly and is used to selectively drive different forming units. The lower die assembly includes a die cavity, a die core, and at least one movable nest. The movable nest can move axially relative to the die core to change the cavity diameter of the lower die assembly, matching it with the working diameter of the selected forming unit in the upper die assembly. The die also includes a blank holder. During operation, the blank holder is first used to fix the sheet-like workpiece, and then a power rod drives the punch, sleeve, and die cavity to cooperate and complete multiple deep-drawing forming processes, thereby gradually forming a cylindrical part from the sheet-like workpiece. However, using this type of stamping die can easily lead to uneven wall thickness in the cylindrical parts after deep drawing. Specifically, the lower sidewalls of the cylindrical parts are slightly thinner, the tangent to the rounded corners at the bottom is significantly thinner, and the opening of the cylindrical parts is the thickest. This can easily cause the parts to crack during deep drawing, thus affecting the stamping quality. Summary of the Invention

[0003] Therefore, it is necessary to provide a fracture-resistant stamping die to address the technical problem that current stamping dies easily cause uneven wall thickness of parts, which affects the stamping quality. The above objectives are achieved through the following technical solutions: A fracture-resistant stamping die includes a frame, an upper die assembly, and a lower die assembly. The frame has a horizontally arranged upper mounting plate and a lower mounting plate corresponding to each other, with the upper mounting plate sliding vertically relative to the lower mounting plate. The upper die assembly includes a punch, a pressure ring, and a suction tube. The punch is fixedly mounted on the upper mounting plate, with its axis extending vertically. A suction cavity is located at the center of the punch, and a radially penetrating suction channel is located at the lower end of the punch. The pressure ring is coaxially sleeved outside the punch and can slide vertically relative to the upper mounting plate. The suction tube is coaxially disposed inside the punch and can slide vertically relative to the upper mounting plate. The lower end of the suction tube is sealed and slidably fitted within the suction cavity, and the upper end of the suction tube is connected to an external vacuum pump. Connection; The lower die assembly includes an annular seat and a die cavity. The annular seat is fixedly mounted on the lower mounting plate. The annular seat is coaxial with the pressure ring and corresponds vertically. The die cavity is coaxially fixed inside the annular seat, and the die cavity has a cavity inside. The punch corresponds vertically with the cavity. In the initial state, the lower end of the suction tube blocks the suction channel. When the upper die assembly approaches the lower die assembly and stamps the workpiece to be processed, the pressure ring can press the edge part of the workpiece to be processed onto the annular seat. The punch can extend into the cavity and draw the center part of the workpiece to be processed into a cylindrical part. At the same time, the punch can move downward relative to the suction tube, so that the suction channel is connected to the suction tube, so that the inner wall of the cylindrical part can fit against the outer peripheral surface of the punch. Furthermore, the suction channel includes multiple suction holes, which are evenly distributed along the circumferential and axial directions of the punch. Furthermore, the lower mounting plate is provided with multiple guide rods extending in the vertical direction, and the upper mounting plate is slidably mounted on the guide rods; the upper mounting plate is provided with multiple guide rods extending in the vertical direction, and the pressure ring is slidably mounted on the multiple guide rods, each guide rod being fitted with a first compression spring, the first compression spring having a tendency to move the pressure ring downward. Furthermore, the center of the punch is provided with a sliding groove extending in the vertical direction. The sliding groove is located above the suction cavity and communicates with the suction cavity. The suction tube is slidably disposed in the sliding groove. The outer peripheral surface of the suction tube is provided with an annular protrusion. The inner peripheral surface of the sliding groove is provided with a first inner stop edge. The annular protrusion and the first inner stop edge are in a blocking engagement in the vertical direction. Furthermore, a movable disk that can slide up and down is coaxially provided inside the cavity. The movable disk is coaxially arranged with the die. Multiple rolls are evenly distributed circumferentially inside the annular seat. The axis of the rolls extends horizontally. Each roll is wound with a tensile strip. Multiple tensile strips are arranged radially through the side walls of the annular seat and the die. The end of each tensile strip away from the roll is connected to the bottom surface of the movable disk. When the punch is drawing the center part of the blank to be processed, it can push the movable disk to move down in the cavity. The downward movement of the movable disk pulls the tensile strip down along the inner wall of the cavity, so that the tensile strip is clamped between the inner wall of the cavity and the blank to be processed, and drives the rolls to unwind. Furthermore, the annular seat is provided with a plurality of mounting slots evenly distributed around the circumference, and each mounting slot is provided with a horizontal shaft. A spiral spring is provided on the horizontal shaft. The drum corresponds to the mounting slot one by one, and the drum is sleeved on the corresponding horizontal shaft through the spiral spring. The spiral spring has the tendency to cause the drum to wind up the tensile strip. Furthermore, the inner wall of the cavity is provided with an elastic rubber ring, and the inner wall surface of the elastic rubber ring is coated with a low-friction coating, which is used to reduce the downward resistance of the tensile band. Furthermore, the end of the tensile belt away from the drum is provided with a fan-shaped connecting part, which is detachably and fixedly connected to the bottom surface of the movable disc. Furthermore, the lower end of the movable disk is provided with a fixed shaft, and the center of the concave mold, the annular seat and the lower mounting plate are provided with a through hole. The fixed shaft can slide up and down through the through hole. The lower mounting plate is provided with a second inner retaining edge at the position corresponding to the through hole. The second inner retaining edge is coaxially arranged with the through hole. A second compression spring is sleeved on the fixed shaft. The upper end of the second compression spring is in a stop engagement with the bottom surface of the movable disk, and the lower end of the second compression spring is in a stop engagement with the second inner retaining edge. The second compression spring has a tendency to make the movable disk move upward. Furthermore, the tensile tape is a Kevlar PU composite tape. The beneficial effects of this invention are: The anti-fracture stamping die provided by the present invention firstly allows for negative pressure suction of the cylindrical part through the suction channel on the punch, causing the inner wall of the cylindrical part to adhere to the outer circumferential surface of the punch, thereby increasing the friction between the cylindrical part and the punch, preventing the lower side wall of the cylindrical part and the tangent point between the side wall and the bottom rounded corner from being subjected to concentrated tensile force and breaking, while making the wall thickness of the cylindrical part more uniform and improving the stamping quality. Secondly, during the deep drawing process of the blank into a cylindrical part, the tensile bands generate a downward frictional force on the blank. This frictional force allows the tensile bands to share the tensile stress on the blank, preventing it from breaking. Furthermore, this frictional force only occurs during the deep drawing process and does not damage the blank surface. Multiple tensile bands are evenly distributed along the circumference of the annular seat, ensuring balanced circumferential stress on the blank, thus resulting in high-quality deep drawing. Third, the first compression spring can provide elastic pressing force, enabling the pressure ring to press the edge of the workpiece to be processed. As the pressure ring gradually approaches the workpiece, the elastic force of the first compression spring gradually increases, which can better prevent the edge of the workpiece from wrinkling during the stretching process. Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of a fracture-resistant stamping die provided in an embodiment of the present invention. Figure 2 This is a front view schematic diagram of a fracture-resistant stamping die provided according to an embodiment of the present invention; Figure 3 This is a side view of a fracture-resistant stamping die provided according to an embodiment of the present invention. Figure 4 for Figure 3 Schematic diagram of sectional view AA (corresponding to the initial state); Figure 5 for Figure 4 A schematic diagram of the second state; Figure 6 for Figure 4 A schematic diagram of the third state; Figure 7 for Figure 6 Enlarged view of the structure at point B in the middle; Figure 8 This is an exploded view of a fracture-resistant stamping die provided in an embodiment of the present invention. in: 101. Lower mounting plate; 1011. Second inner retaining edge; 102. Guide rod; 103. Upper mounting plate; 201. Annular seat; 2011. Spiral spring; 2012. Drum; 202. Die; 2021. Elastic rubber ring; 203. Moving disc; 2031. Second compression spring; 2032. Fixed shaft; 204. Tensile band; 301. Punch; 3011. Suction hole; 3012. Suction cavity; 3013. Slide groove; 3014. First inner retaining edge; 302. Pressure ring; 3021. First compression spring; 3022. Guide rod; 303. Suction tube; 304. Flexible hose; 400. Blank to be processed. Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The component designations used in this document, such as "first" and "second," are merely for distinguishing the described objects and do not have any sequential or technical meaning. The terms "connection" and "linkage" used in this invention, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. like Figures 1 to 8 As shown, an embodiment of the present invention provides a fracture-resistant stamping die (hereinafter referred to as stamping die), which includes a frame, an upper die assembly and a lower die assembly; the frame has an upper mounting plate 103 and a lower mounting plate 101 that are horizontally arranged and correspond to each other, and the upper mounting plate 103 can slide up and down relative to the lower mounting plate 101. The upper mold assembly includes a punch 301, a pressure ring 302, and a suction tube 303. The punch 301 is fixedly mounted on the upper mounting plate 103, and its axis extends vertically. A suction cavity 3012 is located at the center of the punch 301, and a radially penetrating suction channel is located at its lower end. The pressure ring 302 is coaxially sleeved outside the punch 301 and can slide vertically relative to the upper mounting plate 103. The suction tube 303 is coaxially disposed inside the punch 301 and can slide vertically relative to the upper mounting plate 103. The lower end of the suction tube 303 is sealed and slidably fitted within the suction cavity 3012, and the upper end of the suction tube 303 is connected to an external vacuum pump. Specifically, a flexible tube 304 is provided at the upper end of the suction tube 303, and the flexible tube 304 is connected to the external vacuum pump. The lower mold assembly includes an annular seat 201 and a concave mold 202. The annular seat 201 is fixedly mounted on the lower mounting plate 101. The annular seat 201 is coaxial with the pressure ring 302 and corresponds vertically. The concave mold 202 is coaxially fixedly mounted inside the annular seat 201, and the interior of the concave mold 202 is provided with a cavity. The punch 301 corresponds vertically with the cavity. In the initial state, such as Figure 4 As shown, the lower end of the suction tube 303 blocks the suction channel; when the upper mold assembly approaches the lower mold assembly and stamps the blank 400 to be processed, the pressure ring 302 can press the edge part of the blank 400 to be processed onto the annular seat 201, the punch 301 can extend into the cavity and draw the center part of the blank 400 to be processed into a cylindrical part, and at the same time the punch 301 can move down relative to the suction tube 303, so that the suction channel is connected to the suction tube 303, so that the inner wall of the cylindrical part can fit against the outer peripheral surface of the punch 301. In this way, the cylindrical part can be suctioned under negative pressure through the suction channel on the punch 301, so that the inner wall of the cylindrical part is attached to the outer peripheral surface of the punch 301, thereby increasing the friction between the cylindrical part and the punch 301, avoiding the lower side wall of the cylindrical part and the tangent of the side wall and the bottom rounded corner being subjected to concentrated tensile force and breaking, while making the wall thickness of the cylindrical part more uniform and improving the stamping quality. Furthermore, the suction channel includes multiple suction holes 3011, which are evenly distributed along the circumference and axial direction of the punch 301. This allows for uniform suction of the inner wall of the cylindrical part. Simultaneously, as the punch 301 moves downward relative to the suction tube 303, the suction holes 3011 sequentially connect with the suction tube 303 from bottom to top, enabling the cylindrical part to be gradually suctioned from bottom to top, thus maintaining a consistent wall thickness in the deep-drawn cylindrical part. Furthermore, the lower mounting plate 101 is provided with multiple guide rods 102 extending in the vertical direction, and the upper mounting plate 103 is slidably disposed on the guide rods 102; the upper mounting plate 103 is provided with multiple guide rods 3022 extending in the vertical direction, and the pressure ring 302 is slidably disposed on the multiple guide rods 3022. Each guide rod 3022 is fitted with a first compression spring 3021, which has a tendency to move the pressure ring 302 downward. The guide rods 102 ensure the smooth vertical sliding of the upper mounting plate 103, thereby enabling the upper mold assembly to be smoothly aligned with the lower mold assembly. The first compression spring 3021 can provide elastic pressing force, enabling the pressure ring 302 to press the edge portion of the blank 400 to be processed, and as the pressure ring 302 gradually approaches the blank 400 to be processed, the elastic force of the first compression spring 3021 gradually increases, which can better prevent wrinkling of the edge portion of the blank during the stretch forming process. Furthermore, the center of the punch 301 is provided with a groove 3013 extending in the vertical direction. The groove 3013 is located above and communicates with the suction cavity 3012. The suction tube 303 is slidably disposed within the groove 3013. Figure 5 and Figure 7 As shown, the outer circumferential surface of the suction tube 303 is provided with an annular protrusion, and the inner circumferential surface of the slide groove 3013 is provided with a first inner stop 3014. The annular protrusion and the first inner stop 3014 are engaged in a blocking action in the vertical direction. This arrangement limits the sliding stroke of the suction tube 303 and the punch 301, ensuring that the lower end of the suction tube 303 always slides in a sealed manner within the suction cavity 3012, preventing air leakage. The upper mounting plate 103 is driven by a first driving mechanism (not shown in the figure), which drives the upper mounting plate 103 to move up and down along the guide rod 102. The suction tube 303 is driven by a second driving mechanism (not shown in the figure), which drives the suction tube 303 to move up and down relative to the upper mounting plate 103. Furthermore, a movable disk 203 that can slide up and down is coaxially provided inside the cavity. The movable disk 203 is coaxially arranged with the die 202. Multiple rolls 2012 are evenly distributed circumferentially inside the annular seat 201. The axis of the rolls 2012 extends horizontally. Each roll 2012 is wound with a tensile strip 204. The multiple tensile strips 204 are arranged radially through the side walls of the annular seat 201 and the die 202. The end of each tensile strip 204 away from the roll 2012 is connected to the bottom surface of the movable disk 203. When the punch 301 is drawing the center part of the blank 400 to be processed, it can push the movable disk 203 to move down in the cavity. The downward movement of the movable disk 203 pulls the tensile strip 204 down along the inner wall of the cavity, so that the tensile strip 204 is clamped between the inner wall of the cavity and the blank 400 to be processed, and drives the rolls 2012 to unwind. Specifically, the surface of the tensile band 204 facing the blank 400 to be processed is a frosted surface. During the deep drawing process of the blank 400 into a cylindrical part, the tensile band 204 generates a downward frictional force on the blank. This frictional force allows the tensile band 204 to share the tensile stress on the blank, preventing it from breaking. Furthermore, this frictional force only occurs during the deep drawing process and does not damage the surface of the blank. Multiple tensile bands 204 are evenly distributed along the circumference of the annular seat 201, ensuring balanced circumferential stress on the blank and resulting in high-quality deep drawing. Furthermore, the annular seat 201 is provided with multiple circumferentially evenly distributed mounting slots, each containing a horizontal shaft. A spiral spring 2011 is mounted on each horizontal shaft. The drum 2012 corresponds to each mounting slot and is sleeved on the corresponding horizontal shaft via the spiral spring 2011. The spiral spring 2011 has a tendency to cause the drum 2012 to wind up the tensile strip 204. In this way, the tensile strip 204 is always kept taut, automatically adapting to changes in the drawing stroke and automatically resetting without additional drive. Furthermore, the inner wall of the cavity is provided with an elastic rubber ring 2021, and the inner surface of the elastic rubber ring 2021 is coated with a low-friction coating. The low-friction coating is used to reduce the downward resistance of the tensile band 204. The elastic rubber ring 2021 allows the tensile band 204 to adhere to the outer wall of the cylindrical part, and the low-friction coating facilitates the smooth downward movement of the tensile band 204, causing the tensile band 204 to generate frictional force on the cylindrical part. The low-friction coating is a diamond-like carbon coating with a surface roughness Ra of 0.01 μm to 0.1 μm. Furthermore, the end of the tensile band 204 furthest from the drum 2012 is provided with a fan-shaped connecting part, which is detachably and fixedly connected to the bottom surface of the movable disc 203. The fan-shaped structure design makes it easier to fit the bottom surface of the movable disc 203, reduces the likelihood of wrinkles, and makes the tensile band 204 more evenly stressed. Furthermore, the lower end of the movable disk 203 is provided with a fixed shaft 2032. The center of the die 202, the annular seat 201, and the lower mounting plate 101 are all provided with a through hole. The fixed shaft 2032 can slide up and down through the through hole. The lower mounting plate 101 is provided with a second inner retaining edge 1011 at the position corresponding to the through hole. The second inner retaining edge 1011 is coaxially arranged with the through hole. A second compression spring 2031 is sleeved on the fixed shaft 2032. The upper end of the second compression spring 2031 is in a stop engagement with the bottom surface of the movable disk 203, and the lower end of the second compression spring 2031 is in a stop engagement with the second inner retaining edge 1011. The second compression spring 2031 has a tendency to move the movable disk 203 upward. This design facilitates the upward reset of the movable disk 203 and avoids the movable disk 203 from tilting. Furthermore, the tensile belt 204 is a Kevlar-PU composite belt. The Kevlar-PU composite belt will not stretch or deform under stress, ensuring precise force transmission. The PU material's surface is wear-resistant and has a moderate coefficient of friction, thus distributing tensile force without scratching the blank. Based on the above embodiments, the usage principle and working process of the embodiments of the present invention are as follows: In the initial state, such as Figure 4As shown, under the pushing action of the second compression spring 2031, the moving disk 203 is located at the upper position inside the cavity. Under the winding action of the spiral spring 2011, the tensile band 204 remains taut and adheres tightly to the preset position on the inner wall of the cavity. At this time, the lower end of the suction pipe 303 can completely block the suction hole 3011 on the punch 301, and the external vacuum pump is in standby mode. Initiating the stamping operation: First, the blank 400 to be processed is placed on the upper end of the die 202 and the annular seat 201 for positioning. Then, the first drive mechanism is controlled to drive the upper mounting plate 103 to slide downwards along the guide rod 102, causing the upper die assembly to move downwards synchronously. The pressure ring 302 first contacts the edge of the blank 400, and under the elastic action of the first compression spring 3021, presses the edge of the blank against the upper end surface of the annular seat 201, achieving edge positioning. As the upper mounting plate 103 continues to move downwards, the punch 301 extends into the cavity of the die 202, pressing and drawing the center portion of the blank. Figure 5 As shown, the stamping die is in the second state at this time, and the blank is gradually formed into a cylindrical part. As the punch 301 continues to press down, it contacts and pushes the movable disk 203 inside the cavity to move downwards synchronously against the elastic force of the second compression spring 2031. The downward movement of the movable disk 203 pulls multiple tensile bands 204 to move synchronously, and drives the roll 2012 to unwind. At this time, the tensile bands 204 slide downwards along the inner wall of the cavity. Under the action of the elastic rubber ring 2021, the tensile bands 204 always adhere to the outer wall of the cylindrical part, generating uniform downward frictional resistance on the outer wall of the cylindrical part, thereby sharing the tensile force on the lower side wall of the cylindrical part and the tangent point between the side wall and the bottom fillet. Finally, as... Figure 6 and Figure 7 As shown, the stamping die is in the third state, at which point the blank is drawn into a cylindrical part. During the process of drawing the central part of the blank into a cylindrical part, the second drive mechanism keeps the suction tube 303 relatively stationary. The continued downward movement of the punch 301 will cause displacement relative to the suction tube 303, thereby causing the lower end of the suction tube 303 to gradually detach from the blockage of the suction hole 3011, so that the suction hole 3011 is connected to the interior of the suction tube 303 from bottom to top. In this way, the external vacuum pump can uniformly suction the inner wall of the cylindrical part through the suction tube 303, the suction chamber 3012 and the suction hole 3011, so that the inner wall of the cylindrical part can be tightly attached to the outer circumferential surface of the punch 301, increasing the friction between the cylindrical part and the punch 301, avoiding the breakage of the cylindrical part, and ensuring the uniform wall thickness of the cylindrical part, thus improving the stamping quality. After the deep drawing is completed, the first drive mechanism drives the upper mounting plate 103, punch 301, and pressure ring 302 to move upward and reset. The pressure ring 302 gradually separates from the edge of the blank and releases the pressure edge. Under the action of the first compression spring 3021, the pressure ring 302 resets downward. At the same time, the second drive mechanism drives the suction pipe 303 to move upward synchronously with the punch 301, and the lower end of the suction pipe 303 re-seals the suction hole 3011. The moving disk 203 returns to its original position under the elastic reset action of the second compression spring 2031. At the same time, each drum 2012 automatically winds up the tensile strip 204 under the torque of the spiral spring 2011, so that the tensile strip 204 returns to its initial state, thereby completing a single stamping. By repeating the above process, blank feeding and continuous stamping operations can be realized. The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A fracture-resistant stamping die, characterized in that, include: The frame has a horizontally arranged upper mounting plate and a lower mounting plate that are vertically corresponding to each other, and the upper mounting plate can slide up and down relative to the lower mounting plate. The upper mold assembly includes a punch, a pressure ring, and a suction tube. The punch is fixedly mounted on an upper mounting plate, with its axis extending vertically. A suction cavity is located at the center of the punch, and a radially penetrating suction channel is located at its lower end. The pressure ring is coaxially sleeved outside the punch and can slide vertically relative to the upper mounting plate. The suction tube is coaxially disposed inside the punch and can slide vertically relative to the upper mounting plate. The lower end of the suction tube is sealed and slidably fitted within the suction cavity, and the upper end of the suction tube is connected to an external vacuum pump. The lower mold assembly includes an annular seat and a die. The annular seat is fixedly mounted on the lower mounting plate and is coaxial with the pressure ring and corresponds vertically. The die is coaxially fixedly mounted inside the annular seat and has a cavity inside. The punch corresponds vertically with the cavity. In the initial state, the lower end of the suction tube blocks the suction channel. When the upper die assembly approaches the lower die assembly and stamps the workpiece to be processed, the pressure ring can press the edge part of the workpiece to be processed onto the annular seat. The punch can extend into the cavity and draw the center part of the workpiece to be processed into a cylindrical part. At the same time, the punch can move down relative to the suction tube, so that the suction channel is connected to the suction tube, so that the inner wall of the cylindrical part can fit against the outer peripheral surface of the punch.

2. The anti-fracture stamping die according to claim 1, characterized in that, The suction channel includes multiple suction holes, which are evenly distributed along the circumference and axial direction of the punch.

3. The anti-fracture stamping die according to claim 2, characterized in that, The lower mounting plate is provided with multiple guide rods extending in the vertical direction, and the upper mounting plate is slidably mounted on the guide rods; the upper mounting plate is provided with multiple guide rods extending in the vertical direction, and the pressure ring is slidably mounted on the multiple guide rods, each guide rod being fitted with a first compression spring, the first compression spring having a tendency to move the pressure ring downward.

4. The anti-fracture stamping die according to claim 1, characterized in that, The center of the punch is also provided with a sliding groove extending in the vertical direction. The sliding groove is located above the suction cavity and communicates with the suction cavity. The suction tube is slidably disposed in the sliding groove. The outer peripheral surface of the suction tube is provided with an annular protrusion. The inner peripheral surface of the sliding groove is provided with a first inner stop edge. The annular protrusion and the first inner stop edge are in a blocking cooperation in the vertical direction.

5. The anti-fracture stamping die according to claim 1, characterized in that, A movable disk that can slide up and down is coaxially arranged inside the cavity. The movable disk is coaxially arranged with the die. Multiple rolls are evenly distributed circumferentially inside the annular seat. The axis of the rolls extends horizontally. Each roll is wound with a tensile strip. Multiple tensile strips are arranged radially through the side walls of the annular seat and the die. The end of each tensile strip away from the roll is connected to the bottom surface of the movable disk. When the punch is drawing the center part of the blank to be processed, it can push the movable disk to move down in the cavity. The downward movement of the movable disk pulls the tensile strip down along the inner wall of the cavity, so that the tensile strip is clamped between the inner wall of the cavity and the blank to be processed, and drives the rolls to unwind.

6. The anti-fracture stamping die according to claim 5, characterized in that, The annular seat is provided with multiple mounting slots evenly distributed around the circumference. Each mounting slot is provided with a horizontal shaft. A spiral spring is provided on the horizontal shaft. The drum corresponds to each mounting slot, and the drum is sleeved on the corresponding horizontal shaft through the spiral spring. The spiral spring has the tendency to cause the drum to wind up the tensile strip.

7. The anti-fracture stamping die according to claim 5, characterized in that, The inner wall of the cavity is provided with an elastic rubber ring, and the inner wall surface of the elastic rubber ring is coated with a low-friction coating, which is used to reduce the downward resistance of the tensile band.

8. The anti-fracture stamping die according to claim 6, characterized in that, The end of the tensile belt away from the drum is provided with a fan-shaped connecting part, which is detachably and fixedly connected to the bottom surface of the movable disk.

9. The anti-fracture stamping die according to claim 8, characterized in that, The lower end of the movable disk is provided with a fixed shaft. The center of the concave mold, the annular seat and the lower mounting plate are provided with a through hole. The fixed shaft can slide up and down through the through hole. The lower mounting plate is provided with a second inner retaining edge at the position corresponding to the through hole. The second inner retaining edge is coaxially arranged with the through hole. A second compression spring is sleeved on the fixed shaft. The upper end of the second compression spring is in a stop engagement with the bottom surface of the movable disk, and the lower end of the second compression spring is in a stop engagement with the second inner retaining edge. The second compression spring has a tendency to make the movable disk move upward.

10. The anti-fracture stamping die according to claim 9, characterized in that, The tensile tape is a Kevlar PU composite tape.

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