Extrusion forming die for cylindrical member and extrusion forming method thereof

Abstract

The die comprises an upper die assembly and a lower die assembly, the lower die assembly comprises a lower die, the lower die is provided with a die core, and the upper die assembly comprises a fixed die and a movable die detachably connected to the end face of the side, facing the lower die, of the fixed die. The fixed die is provided with an upper die cavity with an opening facing one side of the die core, the movable die is provided with a die hole penetrating through the upper end and the lower end of the movable die, the cavity diameter of the upper die cavity is larger and larger from top to bottom or keeps unchanged, and the hole diameter of the die hole is smaller and smaller from top to bottom. And the space among the upper die cavity, the die hole and the die core forms a forming die cavity of the cylindrical component. The forming flow path of the blank can be regulated and controlled, excessive material overflowing on the parting surface of the upper die assembly and the lower die assembly is avoided, and therefore the material utilization rate and the forming yield of parts are improved.

Description

Technical Field

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

[0002] Lightweighting is one of the fundamental ways to improve equipment performance. Aluminum alloy is the most widely used non-ferrous metal structural material in industry, occupying important structural parts of aerospace, automobile, shipbuilding and other equipment. Among them, 7A04 aluminum alloy has high strength, good heat treatment strengthening effect and is quite mature among super-hard aluminums, so it has become the most commonly used ultra-high-strength aluminum alloy.

[0003] The excellent mechanical properties of the alloy itself are the basis for the high strength of the component. However, the further improvement of the component strength also depends on the specific forming process. Plastic forming is a common way to form metal components. It has high forming efficiency and can effectively improve the mechanical properties. 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-dimensional compressive stress, which greatly improves the organizational performance and further strengthens the component.

[0004] The reverse extrusion process is a commonly used forming process for straight-walled cylindrical parts, which has the advantages of being simple and fast. However, for inverted tapered-wall cylindrical components, the outer portion of the lower half of the component is inclined toward the axis at a certain angle (for example, 6°, that is, the slope or taper is 6°). Therefore, during the specific forming process, reverse extrusion can only be used to extrude the blank into a straight-wall shape (that is, to form a straight-walled cylindrical part), and then turned into the required slope or formed into the required slope using a closing mold, which results in too low material utilization and increases the cost of part processing.

[0005] The forward extrusion process is also subject to the interference of the slope of the outer wall of the part. First, in order to make the part demoulding parting surface after forming, the part must be selected at the position where the slope starts. Due to the action of the core, the lower part of the blank is quickly upset in the early stage of forming until the diameter of the blank exceeds the diameter of the lower die. When the blank contacts the lower die, the flow of part of the material is hindered by the edge of the lower die. As the mold is pressed down, the material whose longitudinal flow is hindered will flow radially along the parting surface, resulting in a large amount of blank accumulation near the lower die. Finally, the upper die is hindered by a large amount of overflow and cannot continue to move downward, resulting in the bottom of the part not being fully filled, and there is a large amount of flash around the part, resulting in waste; at the same time, since the blank can only be placed on the core and extruded downward by the punch, the top corner of the core is large (R30) and the surface is relatively smooth, which causes the blank to be positioned unsteadily. During the forming process, the blank is easy to slide sideways and fall off the core, or the mold drift occurs, causing the core to bend. In order to at least partially solve the above-mentioned deficiencies of the prior art, the present invention is proposed. Summary of the invention

[0006] Therefore, the present invention provides an extrusion forming die for a cylindrical component and an extrusion forming method thereof, which can solve the technical problems of unstable blank positioning, uneven material flow, large part cutting amount, excessive overflow on the parting surface, and poor forming quality in the process of extruding inverted cone wall cylindrical components in the prior art.

[0007] In order to solve the above problems, the present invention provides an extrusion forming die for a cylindrical component, comprising an upper die assembly and a lower die assembly, the lower die assembly comprising a lower die, the lower die having a die core, the upper die assembly comprising a fixed die and a movable die detachably connected to the fixed die on one end face facing the lower die, the fixed die having an upper die cavity opening toward the die core, the movable die having a die hole passing through its upper and lower ends, wherein the cavity diameter of the upper die cavity increases from top to bottom or remains unchanged, and the hole diameter of the die hole decreases from top to bottom, and when the upper die assembly and the lower die assembly are molded together, the space between the upper die cavity, the die hole and the die core forms a forming die cavity for the cylindrical component.

[0008] In some embodiments, a plurality of first connecting grooves are evenly spaced on the outer peripheral wall of the fixed mold, and a plurality of second connecting grooves are evenly spaced on the outer peripheral wall of the movable mold, and the positions of the first connecting grooves correspond one-to-one to the positions of the second connecting grooves. The movable mold also includes a plurality of connecting components, and the connecting components include a connecting strip and a first connecting portion and a second connecting portion connected to both ends of the connecting strip, and the first connecting portions are respectively inserted into the first connecting grooves one-to-one, and the second connecting portions are respectively inserted into the second connecting grooves one-to-one.

[0009] In some embodiments, the connecting strip is a chain, each of the first connecting grooves has a first groove on a side close to the movable mold, and each of the second connecting grooves has a second groove on a side close to the fixed mold. When the movable mold and the fixed mold are assembled into one, the connecting strip is accommodated in a connecting groove formed by the first groove and the second groove.

[0010] In some embodiments, the bottom side opening of the mold hole has a first external expansion opening, the lower mold also includes a mold disc, the mold core is located in the central area of ​​the top surface of the mold disc, the connection position between the mold core and the mold disc forms an annular boss, and the outer circumferential wall of the annular boss forms a first guide cone surface that cooperates with the first external expansion opening.

[0011] In some embodiments, the outer circumferential wall of the movable mold near the bottom end surface forms a second guide cone surface, and a positioning ring is formed in the edge area of ​​the top surface of the mold plate body. The inner ring surface of the positioning ring has a second outer expansion opening. During the mold closing process of the upper mold assembly and the lower mold assembly, the second outer expansion opening and the second guide cone surface form a guiding fit, and the extension length of the second guide cone surface in the axial direction of the movable mold is greater than the extension length of the first outer expansion opening in the axial direction of the movable mold, and the extension length of the second outer expansion opening in the axial direction of the mold plate body is greater than the extension length of the first guide cone surface in the axial direction of the mold plate body.

[0012] In some embodiments, the center of the mold core has a push rod channel that runs through from top to bottom, and a push rod assembly that can be driven to rise and fall is installed in the push rod channel. The push rod assembly includes a push rod and a push plate connected to the top of the push rod, and a receiving groove for receiving the push plate is formed on the top surface of the mold core.

[0013] In some embodiments, a plurality of circles of blank engaging ring grooves are formed on the top surface of the ejector plate and are arranged around the ejector rod; and / or a chamfer is formed between the top surface and the side elevation surface of the mold core, and the radius of the chamfer is equal to the radius of the bottom corner of the inner hole of the cylindrical component; and / or the draft angle of the mold core is a, a=1°.

[0014] In some embodiments, the inner wall of the upper mold cavity has a plurality of stepped ring platforms from top to bottom, and the diameter of each of the stepped ring platforms increases from top to bottom, and the connection position of two adjacent stepped ring platforms is smoothly transitioned.

[0015] The present invention also provides an extrusion forming method using the extrusion forming die of the above-mentioned cylindrical member, comprising the following steps:

[0016] Preparing a rod-shaped blank;

[0017] Preheating the lower mold, the fixed mold, the movable mold and the blank to a preset temperature and keeping them warm for a preset time;

[0018] Assembling the fixed mold and the lower mold on the upper and lower working ends of the press respectively, and connecting the movable mold to the lower end surface of the fixed mold;

[0019] placing the blank on top of the mold core;

[0020] Controlling the upper working end of the press to drive the upper die assembly downward to realize positive extrusion forming of the blank;

[0021] The connection between the fixed mold and the movable mold is released, and the upper working end of the press is controlled to move upward to a preset height.

[0022] In some embodiments, when preparing a rod-shaped blank, a positioning groove is processed on the bottom end face of the blank, and the groove shape of the positioning groove matches the top shape of the mold core. When the blank is placed on the top of the mold core, the positioning groove and the top of the blank are formed to accommodate and fit; and / or, when a ejector rod assembly is installed in the mold core, after controlling the upper working end of the press to move upward to a preset height, the ejector rod assembly is controlled to rise to eject the formed cylindrical component from the mold hole.

[0023] The present invention provides an extrusion forming die and an extrusion forming method of a cylindrical component, which has the following characteristics:

[0024] Beneficial effects:

[0025] The upper die assembly includes a fixed die and a movable die, wherein the die hole of the movable die is an inverted cone hole matching the inverted cone wall of the cylindrical component. During the extrusion forming process of the component, the movable die and the fixed die are connected as a whole to form an upper die assembly to form a complete forming cavity for the cylindrical component together with the die core. The movable die can guide the roughened blank during the extrusion process toward one side of the lower die to prevent the blank from being obstructed during the extrusion deformation process, resulting in excessive overflow of the parting surface, and ensure uniform flow of the material. The blank is more reliably positioned due to the guiding effect of the aforementioned movable die, thereby improving the forming quality of the metal material; at the same time, the corresponding inverted cone outer wall surface is formed after the cylindrical component is extruded, and there is no need to cut parts to form an inverted cone, thereby improving the material utilization rate. It can be understood that after the extrusion forming of the cylindrical component with an inverted cone outer wall surface is completed, the movable die and the fixed die can be disassembled to realize the convenient demolding of the cylindrical component. The present invention combines a fixed mold and a movable mold into a whole, which can adjust the forming flow path of the blank and avoid excessive overflow to the parting surface of the upper mold assembly and the lower mold assembly, thereby improving the material utilization rate and the forming yield rate of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 Schematic diagram of the internal structure of the extrusion forming die of the cylindrical member according to the embodiment of the present invention, showing a blank, and the extrusion forming die at this time is in a state before extrusion forming;

[0028] Figure 2 yes Figure 1A schematic diagram of the state in which the 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;

[0029] Figure 3 1 is a schematic longitudinal section diagram of a cylindrical member formed in a specific embodiment of the present invention (being a body of revolution), and the units of the dimensions shown in the figure are mm;

[0030] Figure 4 is a schematic longitudinal section diagram of a blank (a body of revolution) in one embodiment, and the units of the dimensions shown in the figure are mm;

[0031] Figure 5 yes Figure 1 A schematic diagram of the state in which the fixed mold and the movable mold are assembled and connected as one;

[0032] Figure 6 yes Figure 5 Structural schematic diagram of the fixed mold in (being a rotating body);

[0033] Figure 7 yes Figure 5 A schematic diagram of the structure of the movable mold in FIG. 1 (a rotating body);

[0034] Figure 8 yes Figure 1 Schematic diagram of the structure of the lower mold (a rotating body);

[0035] Fig. 9 yes Figure 1 Schematic diagram of the structure of the ejector plate (a rotating body).

[0036] The accompanying drawings are marked as follows:

[0037] 1. Lower mold; 11. Mold core; 111. Ejector rod channel; 112. Accommodating groove; 12. Mold plate; 13. Annular boss; 131. First guide cone; 14. Positioning ring; 141. Second outer expansion opening; 15. Lower connecting plate; 2. Fixed mold; 21. Upper mold cavity; 211. Stepped ring platform; 22. First connecting groove; 23. First groove; 24. Upper connecting plate; 3. Movable mold; 31. Mold hole; 32. Second connecting groove; 33. Second groove; 34. First outer expansion opening; 35. Second guide cone; 4. Connecting assembly; 41. First connecting part; 42. Second connecting part; 43. Connecting strip; 5. Ejector rod assembly; 51. Ejector rod; 52. Ejector plate; 521. Billet bite ring groove; 100. Billet; 101. Positioning groove. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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, wherein the lower wall surface is an inverted cone section. Figure 3In the embodiment shown, the angle between the generatrix of the inverted cone section and the axis is 6°. It should be noted that Figure 3 The dimensions are only specific values ​​used in a specific embodiment, and their specific values ​​can be reasonably selected according to actual needs, and do not mean that they necessarily limit the technical solution of the present invention. Furthermore, the upper section of the cylindrical component is avoided to be 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 bottom of the cylindrical component to the barrel mouth, and the outer diameter of the first step is greater than the outer diameter of the second step.

[0043] See also Figures 1 to 9 As shown, according to an embodiment of the present invention, there is provided an extrusion forming die for a cylindrical component, comprising an upper die assembly (not labeled in the figure) and a lower die assembly (not labeled in the figure), the lower die assembly comprising a lower die 1, the lower die 1 having a die core 11, the die core 11 being protruded toward one side of the upper die assembly, and being used to form an inner cylindrical hole of the cylindrical component, the upper die assembly comprising a fixed die 2 and a movable die 3 detachably connected to an end surface of the fixed die 2 on one side facing the lower die 1, that is, the movable die 3 can be assembled on the bottom end of the aforementioned fixed die 2 and can be disassembled and removed, the fixed die 2 has an upper die cavity 21 opening toward one side of the die core 11, the movable die 3 has a die hole 31 passing through its upper and lower ends, wherein the cavity diameter of the upper die cavity 21 increases from top to bottom or remains unchanged, for example, it is a straight cylindrical hole or a cavity structure with a small top and a large bottom, so as to facilitate the component and the upper die The demolding between the two cavities 21, the diameter of the die hole 31 becomes smaller from top to bottom, that is, an inverted cone-shaped hole (large at the top and small at the bottom) is formed. When the upper mold assembly and the lower mold assembly are molded together, the space between the upper mold cavity 21, the die hole 31 and the mold core 11 forms a forming mold cavity for the cylindrical component. It can be understood that the aforementioned upper mold cavity 21 is used to form the upper wall surface of the cylindrical component, and the die hole 31 is used to form the lower wall surface of the cylindrical component, and the assembly surfaces of the movable mold 3 and the fixed mold 2 correspond to the connection position between the upper wall surface and the lower wall surface of the cylindrical component; it can be understood that the top end surface of the fixed mold 2 is detachably connected to the upper connecting plate 24, and the bottom end surface of the lower mold 1 is detachably connected to the lower connecting plate 15, so that a reliable connection can be formed with the upper working end of the press through the upper connecting plate 24, and a reliable connection can be formed with the lower working end of the press through the lower connecting plate 15.

[0044] In this technical solution, the upper die assembly includes a fixed die 2 and a movable die 3, wherein the die hole 31 of the movable die 3 is an inverted cone hole matching the inverted cone wall of the cylindrical component. During the extrusion forming process of the component, the movable die 3 and the fixed die 2 are connected as a whole to form an upper die assembly to form a complete forming cavity for the cylindrical component together with the die core 11. The movable die 3 can guide the roughened blank 100 during the extrusion process toward one side of the lower die 1 to prevent the blank 100 from being blocked during the extrusion deformation process, resulting in excessive overflow of the parting surface, and ensure uniform flow of the material. The blank 100 is more reliably positioned due to the guiding effect of the aforementioned movable die 3, thereby improving the forming quality of the metal material; at the same time, the corresponding inverted cone outer wall surface is formed after the cylindrical component is extruded, and there is no need to cut parts to form an inverted cone, thereby improving the material utilization rate. It can be understood that after the extrusion forming of the cylindrical component with an inverted cone outer wall surface is completed, the movable die 3 and the fixed die 2 are disassembled to realize the convenient demoulding of the cylindrical component. That is, the present invention combines the fixed mold 2 and the movable mold 3 into a whole, which can regulate the forming flow path of the blank 100 and avoid excessive overflow to the parting surface of the upper mold assembly and the lower mold assembly, thereby improving the material utilization rate and forming yield rate of the parts.

[0045] In some embodiments, a plurality of first connecting grooves 22 are evenly spaced on the outer peripheral wall of the fixed mold 2, and a plurality of second connecting grooves 32 are evenly spaced on the outer peripheral wall of the movable mold 3, and the positions of the first connecting grooves 22 and the second connecting grooves 32 correspond one-to-one. A plurality of connecting components 4 are also included, and the connecting components include a connecting strip 43 and a first connecting portion 41 and a second connecting portion 42 connected to both ends of the connecting strip 43, and each of the first connecting portions 41 is respectively and one-to-one inserted (clearance fit) into each of the first connecting grooves 22, and each of the second connecting portions 42 is respectively and one-to-one inserted (clearance fit) into each of the second connecting grooves 32.

[0046] In this technical solution, the connection component 4 realizes the connection between the upper and lower components through various connection grooves respectively constructed on the outer peripheral walls of the fixed mold 2 and the movable mold 3. During the specific loading and unloading process, it can be operated from the outer peripheral area of ​​the mold, and the operation process is more convenient.

[0047] In a specific embodiment, the first connecting portion 41 and the second connecting portion 42 both use a convex-shaped clamping head with a cross-sectional shape, a maximum width of 30 mm, and a maximum height of 30 mm. The "convex"-shaped cross-section can enable the clamping head to be more stably placed in the corresponding connecting groove. In order to facilitate the clamping of the clamping head, a rounded corner transition with a radius of R2 (the unit is mm, and the same unit shall apply unless otherwise specified below) is used at the edge position of the clamping head.

[0048] In a preferred embodiment, the connecting bar 43 is a chain, and each of the first connecting grooves 22 has a first groove 23 on the side close to the movable mold 3, and each of the second connecting grooves 32 has a second groove 33 on the side close to the fixed mold 2. When the movable mold 3 and the fixed mold 2 are assembled as one, the connecting bar 43 is accommodated in the connecting groove formed by the first groove 23 and the second groove 33; the first connecting part 41 and the second connecting part 42 are flexibly connected (that is, the length can be adjusted within a certain range, rather than a rigid connection) by the chain. Compared with the rigid connection method, the flexible connection method of the chain has a high fault tolerance rate, which is convenient for the installation and disassembly of the aforementioned clamp (that is, the connecting part), and can avoid the dimensional error of the rigid connection due to the thermal expansion of the mold (which requires the movable mold 3 and the fixed mold 2 to be preheated before the two are connected), thereby resulting in insufficient length of the connection and the inability to connect the fixed mold 2 and the movable mold 3. At the same time, it can also avoid the rigid connection. The mold bends the connection position during the mold closing process, causing damage to the connecting component 4. More importantly, the connecting groove is used to accommodate the chain. When the movable mold 3 swings laterally due to uneven radial force during the forming process, the connecting groove can clamp the chain, thereby limiting the lateral displacement of the movable mold 3 and avoiding excessive wall thickness error of the finished part.

[0049] In a specific embodiment, the chain specification is M3 and the thickness is 2.98mm. Correspondingly, the depth of each connecting groove is 40mm, which is consistent with the length of each connecting part; the length of the first groove 23 and the second groove 33 forming the connecting groove are both 20mm, and together with the two connecting grooves, they can accommodate a chain of 40mm to 50mm in length. The width and depth of the first groove 23 and the second groove 33 are both 10mm.

[0050] See Figure 7 As shown, in some embodiments, the bottom side opening of the die hole 31 has a first outer expansion opening 34, such as Figure 7 As shown, it forms a cone-shaped structure. Correspondingly, Figure 8 As shown, the lower mold 1 also includes a mold plate 12, the mold core 11 is located in the central area of ​​the top surface of the mold plate 12, and the connection position between the mold core 11 and the mold plate 12 forms an annular boss 13, and the outer circumferential wall of the annular boss 13 forms a first guide cone 131 that cooperates with the first outer expansion opening 34. In this way, when the upper mold assembly and the lower mold assembly are in a mold closing state, the first guide cone 131 and the first outer expansion opening 34 are completely matched in shape, which can further improve the extrusion forming quality of the cylindrical component and prevent excessive wall thickness deviation.

[0051] In some embodiments, a second guide cone 35 is formed on the outer circumferential wall of the movable mold 3 near the bottom end surface, and a positioning ring 14 is formed in the top edge area of ​​the mold plate 12, and the inner ring surface of the positioning ring 14 has a second outer expansion opening 141. During the mold closing process of the upper mold assembly and the lower mold assembly, the second outer expansion opening 141 forms a guiding fit with the second guide cone 35, and the extension length of the second guide cone 35 in the axial direction of the movable mold 3 is greater than the extension length of the first outer expansion opening 34 in the axial direction of the movable mold 3, and the extension length of the second outer expansion opening 141 in the axial direction of the mold plate 12 is greater than the extension length of the first guide cone 131 in the axial direction of the mold plate 12.

[0052] In this technical solution, the second outer flared opening 141 and the second guide conical surface 35 form a guiding fit during the extrusion forming process, thereby ensuring that the upper die assembly and the lower die assembly have a high degree of coaxiality, preventing the movable die 3 from being displaced laterally due to uneven material of the blank 100 or movement of the placement position, thereby ensuring the material uniformity of the component forming. That is, during the extrusion forming process, due to the guiding fit between the second outer flared opening 141 and the second guide conical surface 35, the lateral displacement error of the movable die 3 is gradually corrected, the axes of the lower die 1 and the movable die 3 gradually tend to coincide, and the wall thickness of the component gradually tends to be uniform, until the blank 100 is formed. The bottom end contacts the top surface of the annular boss 13 of the lower mold 1. Under the continuous pressure of the fixed mold 2, the first outer expansion port 34 gradually cooperates with the first guide cone 131. Subsequently, a small amount of blank gradually overflows from the gap between the first outer expansion port 34 and the first guide cone 131 to form a flash. Since the flash forms an angle with the axis (15° in the following text), it has little effect on unloading. Finally, since the downward flow of the blank is hindered, the upward flow gradually fills the upper mold cavity 21. Due to the extremely small gap between the fixed mold 2 and the lower mold 1, the blank will first fill the entire mold cavity and there is very little overflow between the fixed mold 2 and the lower mold 1, so there is less flash and turning residue on the parts.

[0053] In a specific embodiment, the angle between the generatrix of the die hole 31 and the axis is equal to the angle between the generatrix of the tapered section of the cylindrical component and the axis, both of which are 6°, and the axial extension length, i.e., the height, is 85.5 mm, while the first flared opening 34 forms an flared angle of 15° opposite to its axis, i.e., the angle between the generatrix of the flared opening and the axis is 15°, and the axial extension length, i.e., the height, is 10 mm. The second guide cone 35 is inclined toward the axis, and has an angle of 15° with the axis, and the axial extension length, i.e., the height, is 45.5 mm.

[0054] See Figure 8As shown, the center of the mold core 11 has a push rod channel 111 which runs through from top to bottom, and the push rod channel 111 is equipped with a push rod assembly 5 which can be driven (manually or mechanically) to rise and fall, and the push rod assembly 5 includes a push rod 51 and a push plate 52 connected (threadedly connected in a specific embodiment) to the top of the push rod 51, and a receiving groove 112 (in a specific embodiment, the diameter is φ38mm and the depth is 15mm) for receiving the push plate 52 is formed on the top surface of the mold core 11. It can be understood that the depth of the aforementioned receiving groove 112 is preferably equal to the thickness of the push plate 52 to ensure smooth extrusion forming of the bottom wall of the inner cylinder hole of the cylindrical component.

[0055] In this technical solution, on the one hand, the ejector rod assembly 5 can be provided to push the component upward after forming to realize demoulding of the component, and on the other hand, the ejector rod 51 can be made of a material with higher hardness, thereby improving the bending resistance of the mold core 11. In particular, when the protrusion height (i.e., extension length) of the mold core 11 is large, the ejector rod 51 can be made of a material with higher hardness than the mold core 11, while ensuring the bending resistance of the mold core 11 and reducing the production cost of the mold. The clearance between the ejector rod 51 and the ejector rod channel 111 should be matched to ensure smooth lifting and lowering, and the smaller the better.

[0056] In some embodiments, a plurality of circles of blank engaging grooves 521 are formed on the top surface of the ejector plate 52 and are arranged around the ejector rod 51. In a specific embodiment, each circle of blank engaging grooves 521 is arranged at equal radial intervals, and the specific number of grooves can be reasonably selected according to the diameter of the ejector plate 52. At the beginning of forming, the material first flows into the blank engaging grooves 521, so that the bottom of the blank is "bitten" by the blank engaging grooves 521, preventing the blank 100 from sliding and collapsing due to unbalanced force, and avoiding bending of the mold core 11. The blank engaging grooves 521 can also control the uniform flow of material in the subsequent forming process, avoiding uneven distribution of the bottom material of the blank on the surface of the mold core 11 due to uneven flow friction, thereby improving the forming quality of the component.

[0057] In a specific embodiment, the radial width of the blank bite ring groove 521 is 1.5mm, the depth is 0.6mm, and the edges of the blank bite ring groove 521 are smoothly transitioned; among the blank bite ring grooves 521 distributed in equidistant concentric circles, the middle diameter of the innermost circle is φ20mm, the radial spacing between each blank bite ring groove 521 is 3mm, and three circles are set.

[0058] A chamfer is formed between the top surface of the mold core 11 and the side elevation (the outer circumferential wall of the mold core 11), and the radius of the chamfer is equal to the radius of the bottom corner of the inner hole of the cylindrical component. At this time, a corresponding positioning groove 101 is constructed on the bottom end surface of the blank 100, so that the bottom end surface of the blank 100 can match with the top end of the mold core 11 to ensure that the position of the blank 100 is reliable and stable. In a specific embodiment, the chamfer radius is R, R = 30mm. It can be understood that the shape of the corresponding positioning groove 101 is the same as the shape of the top end of the mold core 11. In a specific embodiment, see Figure 4 As shown, the positioning groove 101 on the bottom end surface of the aforementioned blank 100 has a depth of 10 mm and a diameter of φ83 mm, while the diameter of the blank 100 is φ114 mm.

[0059] In order to reduce the unloading force, the draft angle of the mold core 11 is a, a=1°. In some embodiments, the inner wall of the upper mold cavity 21 has a plurality of stepped ring platforms 211 from top to bottom, and the diameter of each of the stepped ring platforms 211 increases from top to bottom, so as to be able to form a shape match with the upper wall segment, i.e., the stepped segment, on the outer peripheral wall of the cylindrical component. The connection position of the two adjacent stepped ring platforms 211 is smoothly transitioned to facilitate material flow and filling. Specifically, the aforementioned stepped ring platform 211 includes an upper stepped ring platform matching the aforementioned first step and a lower stepped ring platform matching the second step. The inner ring diameter of the upper stepped ring platform should not be less than the top diameter of the blank 100 (i.e., φ114mm in the previous text), so that the material can first fill the inner ring cavity of the upper stepped ring platform in the early stage of forming, thereby preventing the upper end of the blank 100 from sliding laterally. In another preferred embodiment, the upper mold cavity 21 also has a draft angle of 1°, so that the fixed mold 2 can be demolded smoothly first at the end of forming. In a specific embodiment, the fillet of the upper step ring is R6, the transition fillet radius between the upper step ring and the lower step ring is R5, the fillet of the lower step ring is R2, and the fillet of the bottom end of the lower step ring is R5.

[0060] In a specific embodiment, in order to address the potential problem of insufficient material filling at the corner of the first step of the component, the depth of the lower step ring platform of the mold cavity of the fixed mold 2 is increased by 2 mm on the original basis, so that the end face height of the first step of the component after forming is raised by 2 mm. After optimization, the depth of the first step of the inner cavity of the fixed mold 2 is 18.5 mm, and the depth of the second step is 29.53 mm.

[0061] According to an embodiment of the present invention, there is also provided an extrusion forming method using the extrusion forming die of the above-mentioned cylindrical member, comprising the following steps:

[0062] Preparing a rod-shaped blank 100;

[0063] The lower mold 1, the fixed mold 2, the movable mold 3 and the blank 100 are sent to a furnace for preheating to a preset temperature (430° C. in a specific embodiment) and kept warm for a preset time (3 hours in a specific embodiment);

[0064] Assemble the fixed mold 2 and the lower mold 1 on the upper and lower working ends of the press respectively, and connect the movable mold 3 to the lower end surface of the fixed mold 2;

[0065] Placing the blank 100 on the top of the mold core 11;

[0066] Controlling the upper working end of the press to drive the upper die assembly downward to realize positive extrusion forming of the blank 100;

[0067] The connection between the fixed mold 2 and the movable mold 3 is released, and the upper working end of the press is controlled to move upward to a preset height.

[0068] In some embodiments, when preparing a rod-shaped blank 100, a positioning groove 101 is processed on the bottom end face of the blank 100, and the groove shape of the positioning groove 101 matches the top shape of the mold core 11. When the blank 100 is placed on the top of the mold core 11, the positioning groove 101 and the top of the blank 100 are formed to accommodate and fit; and / or, when a ejector rod assembly 5 is installed in the mold core 11, after controlling the upper working end of the press to move upward to a preset height, the ejector rod assembly 5 is controlled to rise to eject the formed cylindrical component from the mold hole 31.

[0069] The extrusion forming method of the present invention is further described below in conjunction with a specific embodiment:

[0070] Prepare 7A04 metal bar (i.e. the aforementioned blank 100, the same below), turn a positioning groove (i.e. the aforementioned positioning groove 101, the same below) at the bottom of the bar according to the required size, the diameter of the blank is φ114mm, the height is 118mm; the bottom positioning groove has a depth of 10mm, a diameter of φ83mm, and an internal fillet radius of R30;

[0071] The blank 100 is sent to a furnace for preheating to 460°C, and the molds except the buckle (i.e. the aforementioned connecting component 4, the same below) are sent to a furnace for preheating to 430°C, and the blank and the mold are kept warm for 3 hours;

[0072] Take out the mold, and install the fixed mold 2 and the lower mold 1 on the upper and lower working ends of the press respectively;

[0073] The press machine moves down to the mold closing position, and the buckle is installed to connect the fixed mold 2 and the movable mold 3 to form a combined upper mold as a whole;

[0074] The press drives the combined upper die upward;

[0075] Place the ejector device (i.e. the ejector rod assembly 5 mentioned above, the same below) in the mold cavity of the mold core 11;

[0076] The inner cavity of the fixed mold 2 (i.e., the upper mold cavity 21), the inner cavity of the movable mold 3 (i.e., the mold hole 31), the outer surface of the mold core 11 and the upper end surface of the ejector plate 5 are uniformly sprayed with liquid graphite lubricant;

[0077] Take out the blank 100 from the furnace, with the positioning groove of the blank 100 facing downward, and place the blank 100 steadily on the end surface of the mold core 11;

[0078] The press machine presses the combined upper die downward to start positive extrusion forming the part, and the forming ends when it reaches the die closing position. Figure 1 to Figure 2 The upper part of the blank 100 gradually fills the stepped inner cavity (i.e., the upper die cavity 21) of the fixed mold 2, and the lower part is gradually upset. In the process of the lower part of the blank 100 flowing downward, it is constrained by the die hole 31 of the movable mold 3 and continues to flow downward along the die hole 31. Since the die hole 31 constrains the flow direction of the blank, the die opening of the movable mold 3 is prevented from obstructing the thicker lower half of the blank 100, thereby avoiding excessive overflow of the parting surface between the fixed mold 2 and the movable mold 3. When the movable mold 3 descends to contact the second outer expansion opening 141 of the lower mold 1, the second guide cone 35 of the movable mold 3 will slide along the second outer expansion opening 141 of the lower mold 1. As the movable mold 3 continues to descend, under the cooperation and constraint of the second outer expansion opening 141 of the lower mold 1 on the second guide cone 35 of the movable mold 3, the lateral displacement error of the movable mold 3 is gradually corrected, the axes of the two gradually tend to coincide, and the wall thickness of the part gradually tends to be uniform, until the bottom end of the blank 100 contacts the bottom wall of the lower mold 1 (that is, the top surface of the annular boss 13), and the fixed mold 2 Under the continuous pressure of the mold 3, the first outer expansion opening 34 of the movable mold 3 gradually cooperates with the first guiding cone 131 of the lower mold 1, and then a small amount of the blank gradually overflows from the gap between the first outer expansion opening 34 and the first guiding cone 131 to form flash. Since the downward flow of the blank is hindered, it flows upward and gradually fills the stepped corner (that is, the upper mold cavity 21). Due to the extremely small gap between the fixed mold 2 and the lower mold 1, the blank will first fill the entire mold cavity and there is very little overflow between the fixed mold 2 and the lower mold 1, so that the material utilization rate and the forming yield rate of the parts are greatly improved.

[0079] After forming, the press machine keeps the mold clamping position unchanged, removes the buckle, and then the press machine only drives the fixed mold 2 to return to its original position;

[0080] Finally, the ejector plate 52 is pushed by the ejector rod 51 to eject the parts.

[0081] 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.

[0082] 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. An extrusion forming die for a cylindrical component, characterized in that: The invention comprises an upper mold assembly and a lower mold assembly, wherein the lower mold assembly comprises a lower mold (1), the lower mold (1) has a mold core (11), the upper mold assembly comprises a fixed mold (2) and a movable mold (3) detachably connected to the fixed mold (2) on one side end surface facing the lower mold (1), the fixed mold (2) has an upper mold cavity (21) opening toward the mold core (11), the movable mold (3) has a mold hole (31) passing through the upper and lower ends thereof, wherein the cavity diameter of the upper mold cavity (21) increases from top to bottom or remains unchanged, and the hole diameter of the mold hole (31) decreases from top to bottom, and when the upper mold assembly and the lower mold assembly are completely molded, the space between the upper mold cavity (21), the mold hole (31) and the mold core (11) forms a forming mold cavity for a cylindrical component.

2. The extrusion die according to claim 1, characterized in that: The fixed mold (2) has a plurality of first connection grooves (22) evenly spaced apart on its outer peripheral wall, and the movable mold (3) has a plurality of second connection grooves (32) evenly spaced apart on its outer peripheral wall, and each of the first connection grooves (22) corresponds to each of the second connection grooves (32) in a one-to-one manner. The movable mold (3) further comprises a plurality of connection components (4), and the connection components comprise a connection bar (43) and a first connection portion (41) and a second connection portion (42) connected to two ends of the connection bar (43), and each of the first connection portions (41) is inserted into each of the first connection grooves (22) in a one-to-one manner, and each of the second connection portions (42) is inserted into each of the second connection grooves (32) in a one-to-one manner.

3. The extrusion die according to claim 2, characterized in that: The connecting bar (43) is a chain, and each of the first connecting grooves (22) has a first groove (23) on a side close to the movable mold (3), and each of the second connecting grooves (32) has a second groove (33) on a side close to the fixed mold (2). When the movable mold (3) and the fixed mold (2) are assembled into one, the connecting bar (43) is accommodated in a connecting groove formed by the first groove (23) and the second groove (33).

4. The extrusion forming die according to claim 1, characterized in that: The bottom side opening of the mold hole (31) has a first external expansion opening (34), the lower mold (1) also includes a mold plate (12), the mold core (11) is located in the central area of ​​the top surface of the mold plate (12), the connection position between the mold core (11) and the mold plate (12) forms an annular boss (13), and the outer circumferential wall of the annular boss (13) forms a first guiding cone surface (131) that cooperates with the first external expansion opening (34).

5. The extrusion die according to claim 4, characterized in that: The outer circumferential wall of the movable mold (3) close to the bottom end surface forms a second guiding conical surface (35), and the top edge area of ​​the mold plate (12) forms a positioning ring (14), and the inner ring surface of the positioning ring (14) has a second outer expansion opening (141). During the mold closing process of the upper mold assembly and the lower mold assembly, the second outer expansion opening (141) and the second guiding conical surface (35) form a guiding fit, and the extension length of the second guiding conical surface (35) in the axial direction of the movable mold (3) is greater than the extension length of the first outer expansion opening (34) in the axial direction of the movable mold (3), and the extension length of the second outer expansion opening (141) in the axial direction of the mold plate (12) is greater than the extension length of the first guiding conical surface (131) in the axial direction of the mold plate (12).

6. The extrusion forming die according to claim 1, characterized in that: The center of the mold core (11) is provided with a push rod channel (111) which passes through from top to bottom. A push rod assembly (5) which can be driven to rise and fall is installed in the push rod channel (111). The push rod assembly (5) comprises a push rod (51) and a push plate (52) connected to the top end of the push rod (51). A receiving groove (112) for receiving the push plate (52) is formed on the top surface of the mold core (11).

7. The extrusion die according to claim 6, characterized in that: The top surface of the ejector plate (52) is formed with a plurality of circles of blank engaging annular grooves (521) arranged around the ejector rod (51); and / or a chamfer is formed between the top surface and the side elevation of the mold core (11), and the radius of the chamfer is equal to the radius of the bottom fillet of the inner hole of the cylindrical component; and / or the draft angle of the mold core (11) is a, a=1°.

8. The extrusion die according to claim 1, characterized in that: The inner wall of the upper mold cavity (21) has a plurality of stepped ring platforms (211) from top to bottom, and the diameter of each stepped ring platform (211) increases from top to bottom, and the connection position of two adjacent stepped ring platforms (211) is smoothly transitioned.

9. An extrusion molding method using the extrusion molding die of any one of claims 1 to 8, characterized in that: The steps include: Preparing a rod-shaped blank (100); Sending the lower mold (1), the fixed mold (2), the movable mold (3) and the blank (100) to a furnace for preheating to a preset temperature and keeping the temperature for a preset time; The fixed mold (2) and the lower mold (1) are respectively assembled on the upper and lower working ends of the press, and the movable mold (3) is connected to the lower end surface of the fixed mold (2); Placing the blank (100) on the top of the mold core (11); Controlling the upper working end of the press to drive the upper die assembly downward to achieve positive extrusion forming of the blank (100); The connection between the fixed mold (2) and the movable mold (3) is released, and the upper working end of the press is controlled to move upward to a preset height.

10. The extrusion forming method according to claim 9, characterized in that: When preparing a rod-shaped blank (100), a positioning groove (101) is processed on the bottom end face of the blank (100), and the groove shape of the positioning groove (101) matches the top shape of the mold core (11). When the blank (100) is placed on the top of the mold core (11), the positioning groove (101) and the top of the blank (100) are formed to accommodate and fit; and / or, when a ejector rod assembly (5) is installed in the mold core (11), after controlling the upper working end of the press to move upward to a preset height, the ejector rod assembly (5) is controlled to rise to eject the formed cylindrical component from the mold hole (31).

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