Backward extrusion forming die of cylindrical component and backward extrusion forming method of backward extrusion forming die

Abstract

The invention provides a backward extrusion forming die of a cylindrical component and a backward extrusion forming method thereof.The die comprises an upper die assembly and a lower die assembly, the upper die assembly comprises an upper die plate and a punch, the lower die assembly comprises a lower die plate, a bottom die and a dismounting die, a lower die hole is formed in the top face of the bottom die, and a lower die hole is formed in the bottom die; the detachable die is provided with an upper die hole penetrating through the upper end and the lower end of the detachable die, the hole diameter of the upper die hole is larger and larger from top to bottom, and the detachable die comprises a plurality of split dies arranged in the circumferential direction of the lower die hole. The split dies have the closing state that the split dies are spliced to form the upper die hole and the demolding state that the split dies are separated from one another, and when the split dies are in the closing state and die closing of the upper die assembly and the lower die assembly is completed, the space among the lower die hole, the upper die hole and the punch forms a forming die cavity of the cylindrical component. According to the mold, excessive waste of materials in the prior art is effectively avoided, and convenient demolding of the conical shell with the steps formed through the backward extrusion process can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of die extrusion forming, and in particular relates to a reverse extrusion forming die of a cylindrical component and a reverse extrusion forming method thereof. Background Art

[0002] Lightweighting is one of the fundamental ways to improve equipment performance. As a light metal material, aluminum alloy has a density of only one-third of that of iron and has excellent ductility and corrosion resistance. These characteristics make aluminum alloy widely used in aerospace, automobile manufacturing, construction and other fields. 7A04 aluminum alloy is an ultra-high strength aluminum alloy with high strength, good heat treatment strengthening effect and is quite mature in super-hard aluminum. The excellent mechanical properties of the alloy itself are the basis of the high strength of the component. However, the further improvement of the component strength also depends on the specific forming process. Common plastic deformation methods include rolling, extrusion, forging, etc. Extrusion is a processing method that uses a punch or a punch to pressurize the blank placed in the die to produce plastic flow, thereby obtaining a part corresponding to the die hole. During the forming process, the blank will be subjected to three-way compressive stress, which greatly improves the organizational performance and further strengthens the component. Reverse extrusion is an extrusion process in which the direction of the punch movement is opposite to the direction of the blank flow. It has the advantages of simple process and quick forming, and is often used for the forming of cylindrical parts. However, for shells with tapered outer walls, since the diameter of the die opening is smaller than the tapered wall of the shell, the traditional reverse extrusion process has the problem of being unable to demold. If the straight-wall shell is formed first and then turned, it will cause excessive material waste. Summary of the invention

[0003] Therefore, the present invention provides a reverse extrusion forming die and reverse extrusion forming method for a cylindrical component, which can solve the technical problems in the prior art that the cylindrical component with a tapered outer wall cannot be demolded by the reverse extrusion process or that excessive material waste occurs by first forming a straight wall shell and then turning it.

[0004] In order to solve the above problems, the present invention provides a reverse extrusion forming die for a cylindrical component, comprising an upper die assembly and a lower die assembly, wherein the upper die assembly comprises an upper die plate and a punch connected to the bottom surface of the upper die plate, and the lower die assembly comprises a lower die plate, a bottom die connected to the top surface of the lower die plate, and a disassembly die connected to the bottom die, wherein a lower die hole is formed on the top surface of the bottom die, and the aperture of the lower die hole increases from bottom to top or remains unchanged, the disassembly die has an upper die hole passing through its upper and lower ends, and the aperture of the upper die hole increases from top to bottom, the disassembly die comprises a plurality of split dies arranged circumferentially around the lower die hole, each of the split dies has a closed state in which the upper die hole is assembled to form the upper die hole and a demolding state in which the split dies are separated from each other, and when each of the split dies is in the closed state and the upper die assembly and the lower die assembly are molded, the space between the lower die hole, the upper die hole and the punch forms a forming cavity for the cylindrical component.

[0005] In some embodiments, each petal of the split mold is horizontally slidably connected to the bottom mold to enable each petal of the split mold to switch between the closed state and the demolding state in a linear sliding manner.

[0006] In some embodiments, a plurality of shrinkage grooves extending radially inward and outward are formed on the top surface of the base mold, and a sliding guide rail is provided on the bottom surface of each petal of the split mold, and the sliding guide rails of each petal of the split mold are respectively and one by one slidably connected to each of the shrinkage grooves; and / or, a connecting structure is formed on the outer vertical wall of each split mold, and the connecting structure is used to connect with an external push-pull device to realize the state switching of the corresponding split mold by the external push-pull device.

[0007] In some embodiments, the upper die hole includes a forming hole and a matching circular hole at the top of the forming hole, the punch includes a forming core segment and a blocking ring at the top of the forming core segment, the diameter of the blocking ring is equal to the aperture of the matching circular hole; and / or, a plurality of concentrically arranged process grooves are formed on the end face of the punch head.

[0008] In some embodiments, the upper die hole also includes an axial limit groove above the mating circular hole, and the punch also includes an axial limit ring. When the upper die assembly and the lower die assembly are molded together, the bottom surface of the axial limit ring fits against the bottom wall of the axial limit groove.

[0009] In some embodiments, the upper mold assembly also includes an outer sleeve annular mold, which is connected to the bottom surface of the upper mold plate and is coaxially arranged with the punch. When the upper mold assembly approaches the lower mold assembly, the outer sleeve annular mold can be mounted on the radial outer side of the disassembly mold.

[0010] In some embodiments, the outer circumferential wall of the disassembly mold is a first conical side surface that is larger at the bottom and smaller at the top, and the inner ring wall surface of the outer sleeve annular mold is a second conical side surface that is larger at the bottom and smaller at the top, and when the upper mold assembly and the lower mold assembly are molded together, the first conical side surface and the second conical side surface are fitted inside and outside.

[0011] In some embodiments, a plurality of guide posts are connected to the upper template, and the outer sleeve annular mold is sleeved on the outer sides of each of the guide posts through sleeve hole gaps constructed thereon, and each of the guide posts is also sleeved with a spring, and the spring is clamped between the top surface of the outer sleeve annular mold and the bottom surface of the upper template.

[0012] In some embodiments, when a sliding guide rail is provided on the bottom surface of each petal of the split mold, the guide posts are respectively provided on the sliding center line of the sliding guide rail of each petal of the split mold.

[0013] The present invention also provides a reverse extrusion forming method using the reverse extrusion forming die of the cylindrical member, comprising the following steps:

[0014] Preparing a rod-shaped blank;

[0015] Preheating the upper mold assembly, the lower mold assembly and the blank feeding furnace to a preset temperature and keeping them warm for a preset time;

[0016] Assembling the upper die assembly and the lower die assembly on the upper and lower working ends of the press respectively, and applying force to each petal of the split die to put it in the closed state;

[0017] Placing the blank in the lower die hole;

[0018] Controlling the upper working end of the press to drive the upper die assembly downward to achieve reverse extrusion forming of the blank;

[0019] Controlling the upper working end of the compressor to move upward to a preset height so that the bottom surface of the outer sleeve annular mold is higher than the top surface of the disassembly mold;

[0020] The mold splitting of each petal is controlled to switch from the closing state to the demoulding state.

[0021] The reverse extrusion forming die and reverse extrusion forming method of a cylindrical component provided by the present invention have the following beneficial effects:

[0022] The conical portion of the stepped conical shell is formed by splicing a multi-petal split mold. Since the split mold has a closed state and a demolding state, the cylindrical component can be reversely extruded by switching the state of each split mold, thereby effectively avoiding the phenomenon of excessive material waste caused by the prior art of first forming a straight-wall shell and then turning to form a stepped conical shell. At the same time, it can also achieve convenient demolding of the stepped conical shell formed by the reverse extrusion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0024] Figure 1 1 is a schematic structural diagram of a reverse extrusion forming die of a cylindrical member according to an embodiment of the present invention, in which a blank is shown, and the extrusion forming die is in a state before extrusion forming;

[0025] Figure 2 yes Figure 1 A schematic diagram of the state in which the reverse extrusion forming die of the middle cylindrical component is controlled to be extruded by the upper die assembly to achieve mold closing with the lower die assembly and complete the extrusion forming;

[0026] Figure 3 1 is a schematic diagram of the dimensions of a final part formed in a specific embodiment of the present invention (a) and a schematic diagram of the dimensions of a cylindrical component after extrusion forming, and the units of the dimensions not shown in the figure without units are mm;

[0027] Figure 4 yes Figure 1 The cross-sectional view of the punch in FIG. 1 (a body of revolution);

[0028] Figure 5 yes Figure 1 A cross-sectional view of the outer sleeve annular die in FIG. 1 (a body of revolution);

[0029] Figure 6 yes Figure 1 A cross-sectional view of the disassembly mold in FIG. 1 (a rotating body);

[0030] Figure 7 yes Figure 6 A top view of

[0031] Figure 8 yes Figure 1 The cross-sectional view of the bottom mold in (being a body of revolution);

[0032] Fig. 9 yes Figure 8 Top view of the .

[0033] The accompanying drawings are marked as follows:

[0034] 11. Upper template; 12. Punch; 121. Forming die core segment; 122. Blocking ring; 123. Process groove; 124. Axial limit ring; 13. Outer sleeve annular die; 131. Sleeve hole; 21. Lower template; 22. Bottom die; 221. Lower die hole; 222. Shrinking groove; 223. Positioning groove; 224. First step groove; 225. Second step groove; 23. Disassembly die; 230. Parting die; 2301. Sliding guide rail; 2302. Lifting ear connection hole; 231. Upper die hole; 2311. Forming hole; 2312. Matching circular hole; 2313. Axial limit groove; 31. Ejector plate; 32. Ejector rod; 41. Guide column; 411. Spring; 100. Blank; 200. Cylindrical component. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0037] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90° or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0038] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0039] Figure 3 The cylindrical component formed by the technical solution of the present invention is shown. In a specific embodiment, the material is 7A04 aluminum alloy. The cylindrical component has an inner cylindrical hole (not marked in the figure) and an outer circumferential wall. The outer circumferential wall has an upper wall surface and a lower wall surface. The upper wall surface is an inverted cone section. Figure 3 In the embodiment shown in (b), the angle between the generatrix of the inverted cone section and the axis is 4°. It should be noted that Figure 3 The dimensions are only specific values ​​used in a specific embodiment. The specific values ​​can be reasonably selected according to actual needs, and do not necessarily limit the technical solution of the present invention. Furthermore, the lower wall of the cylindrical component is a step section, and the step section has a first step and a second step. The first step and the second step are continuously arranged from the barrel mouth to the barrel bottom of the cylindrical component, and the outer diameter of the first step is greater than the outer diameter of the second step. Figure 3 (b) After a small amount of machining, the final cylindrical component can be formed, such as Figure 3 As shown in (a), the cylindrical component formed by the reverse extrusion forming die and the reverse extrusion forming method of the present invention has a certain processing margin.

[0040] See also Figures 1 to 9As shown, according to an embodiment of the present invention, a reverse extrusion forming die for a cylindrical component is provided, comprising an upper die assembly (not labeled in the figure) and a lower die assembly (not labeled in the figure), wherein the upper die assembly comprises an upper die plate 11 and a punch 12 connected to the bottom surface of the upper die plate 11, and the lower die assembly comprises a lower die plate 21, a bottom die 22 connected to the top surface of the lower die plate 21, and a disassembly die 23 connected to the bottom die 22, wherein a lower die hole 221 is formed on the top surface of the bottom die 22, the aperture of the lower die hole 221 increases from bottom to top or remains unchanged, and the specific size matches the lower size of the cylindrical component to be formed, and the disassembly die 23 has an upper die hole 231 passing through the upper and lower ends thereof, the aperture of the upper die hole 231 increases from top to bottom, and the specific size matches the upper size of the cylindrical component to be formed, for specific cylindrical components, please refer to Figure 3 As shown in (b), the disassembly mold 23 includes a plurality of split molds 230 circumferentially arranged around the lower mold hole 221, and each of the split molds 230 has a closed state in which the upper mold hole 231 is formed and a demolded state in which the split molds 230 are separated from each other. When each of the split molds 230 is in the closed state and the upper mold assembly and the lower mold assembly are completely molded, the space between the lower mold hole 221, the upper mold hole 231 and the punch 12 forms a forming mold cavity (not marked in the figure) of the cylindrical component.

[0041] In this technical solution, the conical part of the conical shell with a step is formed by splicing a multi-petal split mold 230. Since the split mold 230 has a closed state and a demolding state, the reverse extrusion forming of the cylindrical component can be achieved by switching the state of each split mold 230, thereby effectively avoiding the phenomenon of excessive material waste caused by the prior art method of first forming a straight-wall shell and then turning to form a conical shell with a step, and at the same time, it can also achieve convenient demolding of the conical shell with a step formed by the reverse extrusion process.

[0042] In some embodiments, each petal of the split mold 230 is horizontally slidably connected to the bottom mold 22 to enable each petal of the split mold 230 to switch between the closed state and the demolding state in a linear sliding manner.

[0043] In this technical solution, the state switching of the split molds 230 is achieved through the sliding connection between each split mold 230 and the bottom mold 22, which can ensure the accuracy and smoothness of the movement and achieve lateral demoulding.

[0044] In a specific embodiment, a plurality of shrinking grooves 222 extending radially inward and outward are formed on the top surface of the bottom mold 22, and a sliding guide rail 2301 is provided on the bottom surface of each petal of the split mold 230. The sliding guide rails 2301 of each petal of the split mold 230 are respectively and one by one slidably connected to each shrinking groove 222. It can be understood that the cross-sectional shape and size of the aforementioned sliding guide rails 2301 match the cross-sectional shape and size of the shrinking groove 222, so as to achieve a reliable connection between the two and ensure that the two can slide smoothly when needed. The aforementioned shrinking groove 222, that is, the slot size is smaller than the slot cavity size, specifically as Figure 6 and Figure 8 As shown, the cross-sections of the aforementioned shrinking groove 222 and the sliding guide rail 2301 are both T-shaped (or called convex shape).

[0045] In this technical solution, the sliding guide rail 2301 is arranged on the bottom surface of each split mold 230, which can not only realize the sliding connection between it and the bottom mold 22, but also improve the structural strength of each split mold 230, and prevent the weakening of the structural strength of the split mold 230 by opening the aforementioned shrinking groove 222 on the split mold 230; and it can be understood that the thickness (that is, the height) of the aforementioned split mold 230 is limited by the axial length of the tapered outer wall of the tubular component, and the thickness of the aforementioned bottom mold 22 can be thickened below the premise of satisfying the corresponding axial length of the lower part of the tubular component (that is, excluding the part corresponding to the upper mold hole 231), thereby compensating for the weakening of its structural strength due to the construction of the aforementioned shrinking groove 222.

[0046] In a specific embodiment, the aforementioned sliding guide rail 2301 is located on the angular bisector of each split mold 230, and each sliding guide rail 2301 and each shrinking groove 222 have a H7 / h6 clearance fit relationship. The sliding guide rail 2301 starts from the edge of the bottom of the outer inclined wall of the corresponding split mold 230 (that is, the bottom of the side of the first truncated cone described later), and extends 150mm radially inward along the split mold 230. The cross section of the sliding guide rail 2301 connected to the aforementioned outer inclined wall is a straight wall. The total width of the "convex"-shaped cross section of the sliding guide rail 2301 is 120mm, the total height is 40mm, and the height of the first step of the "convex" cross section is 20mm, and the width is 40mm.

[0047] A connection structure (not marked in the figure) is formed on the outer wall of each split mold 230, and the connection structure is used to connect with an external push-pull device (not shown in the figure) to realize the state switching of the corresponding split mold 230 by the external push-pull device. In a specific embodiment, the aforementioned connection structure can be specifically a lifting ear connection hole 2302, which is specifically a threaded hole, and the hole depth extension direction of the threaded hole coincides with the sliding guide direction of the aforementioned sliding guide rail 2301. In the specific operation process, the lifting ear (not shown in the figure) is threadedly connected to the corresponding lifting ear connection hole 2302, and then connected to the aforementioned lifting ear through the corresponding push-pull rod on the aforementioned external push-pull device, thereby realizing the smooth switching of the state of each split mold 230, and the entire closing and demolding operation is very simple and convenient, which is conducive to industrial mass production. It is worth noting that when the aforementioned push-pull rod is used to connect with the lifting ear, the push-pull direction should be consistent with the length extension direction of the sliding guide rail 2301 to ensure smooth sliding.

[0048] In a specific embodiment, the center of the aforementioned lifting ear connection hole 2302 is located at a position 20 mm away from the upper end surface (ie, the top surface) of the split mold 230, and the lifting ear connection hole 2302 is adapted to the lifting ear of M24.

[0049] In some embodiments, the upper die hole 231 includes a forming hole 2311 and a matching circular hole 2312 at the top of the forming hole 2311, and the punch 12 includes a forming core segment 121 and a blocking ring 122 at the top of the forming core segment 121, and the diameter of the blocking ring 122 is equal to the aperture of the matching circular hole 2312. In this way, when the upper die assembly and the lower die assembly are completed, the blocking ring 122 and the matching circular hole 2312 form a complete inner and outer fitting, preventing the blank from overflowing from the top of the upper die hole 231 during the reverse extrusion process, thereby ensuring that the material is filled during the reverse extrusion process.

[0050] In a preferred embodiment, a plurality of concentrically arranged process grooves 123 are formed on the end face of the head of the punch 12, into which the blank is flowed in the initial stage of forming to fix the blank, thereby preventing the blank from slipping and ensuring the forming quality. In a specific embodiment, the process grooves 123 are arranged in three circles, and the three circles of process grooves 123 are distributed in equidistant concentric circles. The width of the process grooves 123 is 1.5 mm, the depth is 0.6 mm, the mid-diameter spacing of the process grooves 123 is 6 mm, and the mid-diameter of the innermost circle process groove 123 is φ10 mm. The edges of the process grooves 123 are all smooth transitions, so that the flow resistance of the material in the process grooves 123 can be reduced.

[0051] In some embodiments, the upper die hole 231 also includes an axial limit groove 2313 located above the matching circular hole 2312, that is, from top to bottom in the axial direction of the upper die hole 213, the axial limit groove 2313, the matching circular hole 2312 and the forming hole 2311 are arranged adjacent to each other in sequence, and the punch 12 also includes an axial limit ring 124. When the upper die assembly and the lower die assembly are molded, the bottom surface of the axial limit ring 124 fits with the bottom wall of the axial limit groove 2313. In the actual forming process, the upper die assembly descends under the action of the press, and the axial limit ring 124 will eventually fit with the bottom wall of the axial limit groove 2313 and form an axial limit for the downward movement of the press.

[0052] It can be understood that the punch 12 at this time forms a structure with multiple steps from top to bottom. At this time, the bottom end face of the punch 12 (that is, the head end face mentioned above) is defined as the first working end, the bottom end face of the blocking ring platform 122 is the second working end, and the bottom end face of the axial limiting ring platform 124 is the third working end. In a specific embodiment, the first working end of the punch 12 and the adjacent side wall are transitioned by a fillet with a radius of R30. Taking the first working end as a reference, the distance from the first working end to the second working end is 122.5 mm, which is 9 mm more than the depth of the inner cavity of the part. In this way, see Figure 3 (b) A 9mm height margin is added to the tapered outer wall of the part; the diameter of the second working end is φ139.8mm, which is larger than the φ34.9mm of the first working end; the diameter of the third working end is φ200mm, which is larger than the diameter of the second working end; the distance between the second working end and the third working end is 15mm, and the second working end, the third working end and the adjacent side wall are all rounded with a radius of R3; in this way, see Figure 2 The second working end enters into the matching circular hole 2312 of the disassembly die 23 in the later stage of forming, providing downward resistance for the blank, so that the blank flows to the positions such as the stepped corners with large flow resistance, and gradually fills the entire cavity; the third working end of the punch 12 enters into the axial limit groove 2313 of the disassembly die 23, and fits with the bottom wall of the axial limit groove 2313, preventing the upper die assembly from further descending, and providing a downward limit for the press.

[0053] In a specific embodiment, the side wall between the first working end and the second working end of the punch 12 has a draft angle of 2°, so that the punch 12 is easily demolded from the inner cavity of the part. In another specific embodiment, the diameter of the aforementioned axial limit groove 2313 is φ200mm and the depth is 10mm, and the forming die core segment 121 of the punch 12 and the axial limit groove 2313 form an internal and external clearance fit.

[0054] In some embodiments, the upper mold assembly also includes an outer sleeve annular mold 13, which is connected to the bottom surface of the upper mold plate 11 and is coaxially arranged with the punch 12. When the upper mold assembly approaches the lower mold assembly, the outer sleeve annular mold 13 can be mounted on the radial outer side of the disassembly mold 23, so that during the reverse extrusion forming process, the outer sleeve annular mold 13 covers each of the split molds 230. In this way, the lateral deformation resistance of the blank 100 can be prevented from pushing open each of the split molds 230, thereby ensuring the forming quality. What needs to be particularly emphasized is that the aforementioned outer sleeve annular mold 13 rises and falls synchronously with the upper mold assembly. When performing reverse extrusion, it wraps and holds each petal of the split mold 230 tightly to ensure the forming quality of the blank. After forming is completed, it rises along with the rise of the upper mold assembly, releasing the holding and closing force on each petal of the split mold 230, so that each split mold 230 can be smoothly switched from a closed state to a demolding state, which makes the forming method of the present invention more automated, further improves production efficiency, and is conducive to mass production.

[0055] In some embodiments, the outer circumferential wall of the disassembly mold 23 is a first truncated cone side surface that is larger at the bottom and smaller at the top, and the inner circumferential wall surface of the outer sleeve annular mold 13 is a second truncated cone side surface that is larger at the bottom and smaller at the top, and when the upper mold assembly and the lower mold assembly are molded together, the first truncated cone side surface and the second truncated cone side surface fit together inside and outside, so that the outer sleeve annular mold 13 can wrap each split mold 230 while ensuring the concentricity of the two. In a specific embodiment, the inclination angles of the first truncated cone side surface and the second cone side surface are equal, both of which are 1°.

[0056] In some embodiments, a plurality of guide posts 41 are connected to the upper template 11, and the outer sleeve annular mold 13 is gap-fitted to the outer sides of each of the guide posts 41 through a socket hole 131 constructed thereon. Each of the guide posts 41 is also provided with a spring 411 (also known as a compression spring), and the spring 411 is clamped between the top surface of the outer sleeve annular mold 13 and the bottom surface of the upper template 11. The aforementioned guide posts 41 can be specifically formed by bolts and nuts threadedly connected to the bolt heads (in a specific embodiment, M30 bolts and matching nuts).

[0057] Specifically, a gap is left between the outer sleeve annular mold 13 and the upper mold plate 11, and the aforementioned spring 411 is located on the guide column 41 corresponding to the gap. During the forming process, the upper and lower ends of the compression spring respectively press the upper mold plate 11 and the outer sleeve annular mold 13 tightly, prompting the outer sleeve annular mold 13 to push down the split molds 230 of each petal, offsetting the upward deformation resistance, thereby avoiding warping and deformation of the sliding guide rail 2301, improving the structural stiffness of the outer sleeve annular mold 13, and avoiding dislocation of the outer sleeve annular mold 13 due to uneven radial force.

[0058] In a specific embodiment, the width of the gap between the outer sleeve annular mold 13 and the upper mold plate 11 is 90mm; the wire diameter of the compression spring is φ8mm, the inner diameter is φ34mm, and the outer diameter is φ40mm; the compression spring brand is 30W4Cr2VA, so that the compression spring has the property of high temperature resistance.

[0059] In some embodiments, when a sliding guide rail 2301 is provided on the bottom surface of each petal of the split mold 230, the guide column 41 is respectively arranged on the sliding center line of the sliding guide rail 2301 of each petal of the split mold 230, that is, the projection of the center line of each guide column 41 in the vertical direction is on the center line of the sliding guide rail 2301 (that is, the sliding center line, which is in the diameter direction of the disassembly mold 23). With such an arrangement, during the reverse extrusion forming process, each split mold 230 is subjected to the influence of radial deformation resistance under the deformation of the blank 100 therein, and has the effect of sliding along the aforementioned sliding guide rail. The guide rail 2301 has a tendency to slide in the guiding direction, so that each split mold 230 applies a force to the outer sleeve annular mold 13 in the corresponding area. At this time, a guide column 41 is set on the area to offset the above-mentioned force, that is, the guide column 41 is set on the sliding center line of the sliding guide rail 2301 of each split mold 230, which can improve the structural rigidity of the outer sleeve annular mold 13. At the same time, it can also prevent the sliding center line of the sliding guide rail 2301 from deviating from the above-mentioned action to form a bending moment on the sliding guide rail 2301, and prevent the bending of the sliding guide rail 2301 to increase its service life. Of course, it can be understood that in addition to setting each guide column 41 on the center line of each sliding guide rail 2301, multiple guide columns 41 can be added in other areas to further improve the overall structural rigidity of the outer sleeve annular mold 13. In another preferred embodiment, each of the above-mentioned guide columns 41 is on the same equal diameter circle, and the above-mentioned equal diameter circle is coaxial with the punch 12.

[0060] In a specific embodiment, Figure 7 As shown, the disassembly mold 23 is formed by combining four sub-molds 230 with completely identical structures. At this time, the upper mold hole 231 is formed on each sub-mold 230 by one quarter, and a complete upper mold hole 231 is formed when each sub-mold 230 is in a closed state. In another specific embodiment, a total of 6 guide posts 41 are provided, of which four guide posts 41 correspond to the left-right symmetrical center lines of the sliding guide rails 2301 of each sub-mold 230 (that is, the aforementioned sliding center lines), that is, they are perpendicular to each other, and the other two are respectively located on a 180° parting surface of the disassembly mold 23.

[0061] The lower die hole 221 is specifically a stepped inner cavity, which includes a positioning groove 223, a first stepped groove 224, and a second stepped groove 225 from bottom to top, and the aperture is getting larger and larger. In a specific embodiment, the end surface of the first stepped groove 224 is 5mm lower than the bottom end of the first step corresponding to the part. Figure 3 (b), which adds 5mm thickness margin to the bottom wall of the part; the end surface of the second stepped groove 225 moves 5mm downward compared to the end surface of the second step of the part, so, see Figure 3 (b), which adds 5mm height margin to the second step of the part; the top of the lower die hole 221 moves 5mm downward than the part, so, again refer to Figure 3 (b) This adds 5mm of height margin to the third step down of the part. Figure 3 As shown in (b), the slope of the forming hole 2311 of the upper die hole 231 is 4°, which is 2° smaller than the slope of the tapered outer wall of the part. In this way, the thickness margin of the outer tapered wall of the part is increased.

[0062] In a preferred embodiment, the side walls of the first stepped groove 224 and the second stepped groove 225 of the lower die hole 221 are both provided with a draft angle of 1°, and the step corners are both smoothly transitioned, thereby reducing the flow friction resistance of the material.

[0063] See also Figure 8 The positioning groove 223 of the lower die hole 221 is located below the first stepped groove 224, so that the blank can be accurately placed in the center of the inner cavity of the lower die hole 221, improving the uniformity of the blank flowing to the surroundings. In a specific embodiment, the positioning groove 223 has a depth of 1mm and a diameter of φ101mm, which is larger than the diameter of the blank φ100mm, so that it is convenient to place the blank in the positioning groove 223; the edge of the positioning groove 223 adopts a smooth transition, so that the fluidity of the blank in the positioning groove 223 can be improved.

[0064] In a specific embodiment, it also includes a ejector plate 31 in the aforementioned positioning groove 223. The ejector plate 31 participates in the forming of the part as a part of the inner cavity of the lower mold hole 221. The ejector plate 31 and the ejector rod 32 are screwed together and placed in the cavity at the bottom of the lower mold hole 221 during the forming process. The diameter of the ejector plate 31 is φ80 mm, and the diameter of the ejector rod is φ30 mm.

[0065] According to an embodiment of the present invention, there is also provided a reverse extrusion forming method using the reverse extrusion forming die of the above-mentioned cylindrical member, comprising the following steps:

[0066] Preparing a rod-shaped blank 100;

[0067] Send the upper mold assembly, the lower mold assembly and the blank 100 to a furnace for preheating to a preset temperature and keeping the temperature for a preset time;

[0068] Assemble the upper mold assembly and the lower mold assembly on the upper and lower working ends of a press (not shown in the figure), respectively, and apply force to each petal of the split mold 230 to put it in the closed state;

[0069] The blank 100 is placed in the lower die hole 221;

[0070] Controlling the upper working end of the press to drive the upper die assembly downward to achieve reverse extrusion forming of the blank 100;

[0071] Controlling the upper working end of the compressor to move upward to a preset height so that the bottom surface of the outer sleeve annular mold 13 is higher than the top surface of the disassembly mold 23;

[0072] The split mold 230 of each petal is controlled to switch from the closed state to the demoulding state.

[0073] The above-mentioned reverse extrusion forming method of the present invention is described below in conjunction with a specific embodiment:

[0074] Cut 7A04 aluminum alloy bars and prepare blanks with a size of φ100×166mm to ensure that the cut end surface is flat;

[0075] Preheat the mold assembly (i.e., the upper mold assembly and the lower mold assembly) to 430° C. (the ejector plate 31 and the ejector rod 32 are not preheated) and keep the temperature for 5 to 6 hours; and preheat the blank 100 to 460° C. and keep the temperature for 3 to 4 hours;

[0076] Take out the mold from the furnace, and install the upper mold assembly and the lower mold assembly on the upper and lower working ends of the press respectively;

[0077] The press drives the upper die assembly upward and returns to its original position;

[0078] Install four M24 lifting ears on the lifting ear connection holes 2302 of the split mold 230, pull to separate the split molds 230 from each other, connect the ejection plate 31 with the ejection rod 32 and place it in the inner cavity of the lower mold hole 221;

[0079] The first working end surface, the second working end surface, the side wall surface between the first working end and the second working end of the punch 12, the inner cavity of the lower die hole 221 and the upper surface of the ejector plate 31 are evenly coated with liquid graphite lubricant; the outer inclined wall of the split die 230 (i.e., the first truncated cone side surface mentioned above) and the surface of the sliding guide rail 2301 are evenly coated with high temperature resistant grease;

[0080] The blank is taken out from the furnace and placed in the positioning groove 223 at the bottom of the cavity of the lower die hole 221;

[0081] Combine the separated split molds 230 together, and remove the lifting ears on the outer inclined walls of the split molds 230;

[0082] The blank 100 is taken out of the furnace and stably placed in the positioning groove 223 in the cavity of the lower die hole 221;

[0083] Bring together the separated split molds 230 and remove the lifting ears;

[0084] The press moves downward and begins to back-extrude the part.

[0085] Specifically, see Figure 1 to Figure 2 At the beginning of forming, the first working end of the punch 12 presses the blank 100 downward, and the upper end of the blank 100 first flows radially along the surface of the first working end, and at the same time, the lower end flows radially along the surface of the positioning groove 223 of the lower die hole 221, and the middle part of the blank 100 flows in the radial direction where the flow resistance is the smallest, and undergoes upsetting deformation. The roughening speed of the middle part of the blank 100 is faster than that of the upper and lower ends; as the press machine descends, the middle part of the blank 100 gradually thickens until it approaches the inner inclined wall of the parting die 230 (that is, the forming hole 2311), at which time the outer ring die 13 has descended to the parting die 230 position; the press machine continues to descend, and the inner inclined wall of the outer ring die 13 (that is, the aforementioned second truncated cone side) begins to cover the outer inclined wall of the parting die 230, and the upper part of the blank 100 The upper and middle parts gradually fill the cavity between the punch 12 and the parting die 230, and the lower part gradually fills the cavity between the lower die hole 221 and the punch 12. In this process, the blank 100 forms a radial deformation resistance and an upward deformation resistance to the parting die 230, which are respectively offset by the outer ring die 13 itself and the compression spring between the outer ring die 13 and the upper die plate 1 (that is, the aforementioned spring 411); in the later stage of forming, the blank 100 flows upward and contacts the second working end of the punch 12. After being resisted by the second working end, the blank 100 begins to flow to the corner area with greater friction resistance and gradually fills the entire mold cavity; when the third working end of the punch 12 touches the bottom wall of the axial limit groove 2313 of the parting die 230, the pressure increases sharply, and the press stops descending at this time.

[0086] The press machine is operated to drive the upper mold assembly to return to its original position, the ear is installed on the ear connection hole 2302 of the split mold 230, and the split mold 230 is pulled to separate the split molds 230 from each other along the sliding guide rail 2301; finally, the ejector rod 32 pushes the ejector plate 31 to eject the formed cylindrical component 200. Figure 3 (b)) is designed for margin, so the cylindrical member 200 is finally machined to the corresponding size by turning (i.e. Figure 3 (a)).

[0087] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A reverse extrusion forming die for a cylindrical component, characterized in that: The invention comprises an upper die assembly and a lower die assembly, wherein the upper die assembly comprises an upper die plate (11) and a punch (12) connected to the bottom surface of the upper die plate (11), and the lower die assembly comprises a lower die plate (21), a bottom die (22) connected to the top surface of the lower die plate (21), and a disassembly die (23) connected to the bottom die (22), wherein a lower die hole (221) is formed on the top surface of the bottom die (22), and the hole diameter of the lower die hole (221) increases from bottom to top or remains unchanged, and the disassembly die (23) has an upper die hole (221) penetrating the upper and lower ends thereof. 231), the diameter of the upper die hole (231) increases from top to bottom, the disassembly die (23) includes a plurality of split dies (230) arranged circumferentially around the lower die hole (221), each of the split dies (230) having a closed state in which the upper die hole (231) is assembled and formed, and a demolding state in which the split dies (230) are separated from each other, and when each of the split dies (230) is in the closed state and the upper die assembly and the lower die assembly are completely molded, the space between the lower die hole (221), the upper die hole (231) and the punch (12) forms a forming cavity for the cylindrical component.

2. The reverse extrusion forming die according to claim 1, characterized in that: Each petal of the split mold (230) is horizontally slidably connected to the bottom mold (22) so as to enable each petal of the split mold (230) to switch between the closed state and the demoulding state in a linear sliding manner.

3. The reverse extrusion forming die according to claim 2, characterized in that: A plurality of shrinking grooves (222) extending radially inward and outward are formed on the top surface of the bottom mold (22), and each petal of the split mold (230) has a sliding guide rail (2301) on the bottom surface, and each petal of the split mold (230) has a sliding guide rail (2301) that is respectively and one-to-one slidably connected to each shrinking groove (222); and / or, a connecting structure is formed on the outer wall of each split mold (230), and the connecting structure is used to connect with an external push-pull device to realize the state switching of the corresponding split mold (230) by the external push-pull device.

4. The reverse extrusion forming die according to claim 1, characterized in that: The upper die hole (231) comprises a forming hole (2311) and a matching circular hole (2312) at the top of the forming hole (2311); the punch (12) comprises a forming die core segment (121) and a blocking ring (122) at the top of the forming die core segment (121); the diameter of the blocking ring (122) is equal to the aperture of the matching circular hole (2312); and / or a plurality of concentrically arranged process grooves (123) are formed on the end face of the head of the punch (12).

5. The reverse extrusion forming die according to claim 4, characterized in that: The upper die hole (231) further includes an axial limit groove (2313) located above the matching circular hole (2312), and the punch (12) further includes an axial limit ring (124). When the upper die assembly and the lower die assembly are completely molded, the bottom surface of the axial limit ring (124) fits with the bottom wall of the axial limit groove (2313).

6. The reverse extrusion die according to any one of claims 1 to 5, characterized in that: The upper die assembly also includes an outer sleeve annular die (13), which is connected to the bottom surface of the upper die plate (11) and is coaxially arranged with the punch (12). When the upper die assembly approaches the lower die assembly, the outer sleeve annular die (13) can be mounted on the radial outer side of the disassembly die (23).

7. The reverse extrusion forming die according to claim 6, characterized in that: The outer circumferential wall of the disassembly mold (23) is a first truncated cone side surface that is larger at the bottom and smaller at the top, and the inner ring wall surface of the outer sleeve annular mold (13) is a second truncated cone side surface that is larger at the bottom and smaller at the top, and when the upper mold assembly and the lower mold assembly are molded together, the first truncated cone side surface and the second truncated cone side surface are fitted inside and outside.

8. The reverse extrusion forming die according to claim 6, characterized in that: A plurality of guide posts (41) are connected to the upper template (11); the outer sleeve annular mold (13) is sleeved on the outer sides of each of the guide posts (41) through sleeve holes (131) constructed thereon; each of the guide posts (41) is also sleeved with a spring (411), and the spring (411) is clamped between the top surface of the outer sleeve annular mold (13) and the bottom surface of the upper template (11).

9. The reverse extrusion forming die according to claim 8, characterized in that: When a sliding guide rail (2301) is provided on the bottom surface of each petal of the split mold (230), the guide column (41) is respectively arranged on the sliding center line of the sliding guide rail (2301) of each petal of the split mold (230).

10. A reverse extrusion forming method using the reverse extrusion forming die of any one of claims 6 to 9, characterized in that: The steps include: Preparing a rod-shaped blank (100); Sending the upper mold assembly, the lower mold assembly and the blank (100) to a furnace for preheating to a preset temperature and keeping the temperature for a preset time; Assembling the upper mold assembly and the lower mold assembly on the upper and lower working ends of the press respectively, and applying force to each petal of the split mold (230) to put it in the closed state; Placing the blank (100) in the lower die hole (221); Controlling the upper working end of the press to drive the upper die assembly downward to achieve reverse extrusion forming of the blank (100); Controlling the upper working end of the compressor to move upward to a preset height so that the bottom surface of the outer sleeve annular mold (13) is higher than the top surface of the disassembly mold (23); The split mold (230) of each petal is controlled to switch from the closed state to the demoulding state.

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