A die for large-size conical cylindrical die forging and a forming method thereof

Abstract

The present application discloses a die and a forming method for a large-sized conical cylindrical die forging, which relates to the field of aerospace hot forming technology, wherein the method comprises: forging an ingot into a billet, wherein the billet is an annular cylindrical billet with a hollow interior; assembling the billet with a forging die; using the forging die to expand the hollow inner cavity of the billet toward the outside of the billet, and then compositely extruding the inner and outer walls of the billet to form a conical cylindrical die forging with a bottom inner flange structure; the present application solves the problems of large projected area and high forming load requirement during the die forging forming process by "expanding first and then extruding" the billet, and at the same time, a conical cylindrical structure with a bottom inner flange structure is formed by the forging die, which has the characteristics of reducing the forming projected area and load requirement, facilitating the separation of the die forging after forming from the forming die, and improving the raw material utilization rate of the die forging.

Description

Technical Field

[0001] The present application relates to the field of aerospace hot forming technology, and in particular to a die and a forming method of a large-sized conical cylindrical die forging. Background Art

[0002] In recent years, die forgings have been favored by more and more forging industries due to their good quality consistency, high mechanical property margin and fiber streamline distribution along the forging contour, good application prospects and greater economic benefits.

[0003] In the related art, the production of large-sized die forgings has the problems of large projected area and high forming load requirements. Ordinary lower tonnage presses are difficult to meet the forming requirements. At the same time, the material utilization rate of the die forgings is low and the deformation dead zone at the bottom of the cylindrical forgings cannot be removed.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The technical task of the present application is to address the above deficiencies and provide a die and a forming method for a large-sized conical cylindrical die forging. By "expanding first and then extruding" the blank, the problems of large projected area and high forming load requirement during the die forging forming process are solved. At the same time, a conical cylindrical structure with a bottom inner flange structure is formed by the forging die, which has the advantages of reducing the forming projected area and load requirement, facilitating the separation of the formed die forging from the forming die, and improving the raw material utilization rate of the die forging.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] According to one aspect of the present application, a forming method for a large-sized conical cylindrical die forging is provided, comprising: forging an ingot into a blank, wherein the blank is an annular cylindrical blank with a hollow interior; assembling the blank with a forging die; using the forging die to expand the hollow inner cavity of the blank toward the outside of the blank, and then compositely extruding the inside and outside of the blank to form a conical cylindrical die forging with a bottom inner flange structure.

[0008] In some embodiments, the step of assembling the blank with the forging die includes: heating the blank to 460-470°C and keeping the heated blank warm for 1.5-2.0 min / mm×D 坯料 , where D 坯料is the effective thickness of the blank; preheating the forging die to above 400° C.; placing the blank in the lower concave die of the forging die, and placing the upper convex die just above the hollow cavity of the blank.

[0009] In some embodiments, the expansion is a process in which, during the process of pressing the upper punch downward using a pressure device, the hollow inner cavity of the blank is expanded toward the outside of the blank until the outer wall of the upper punch gradually contacts and completely fits the inner wall of the blank; the composite extrusion is a process in which the upper punch continues to be pressed downward, and the upper punch and the lower die extrude the blank in both positive and negative directions, ultimately forming the conical cylindrical die forging with a bottom inner flange structure; the final forging temperature after the composite extrusion is completed is greater than or equal to 370°C.

[0010] In some embodiments, the initial extrusion rate of the composite extrusion is 3-5 mm / s. When the extrusion stroke reaches three-fifths of the inner cavity height of the conical cylindrical die forging or the forming load exceeds two-thirds of the capacity load of the pressure equipment, the extrusion rate drops to 1.6-2.2 mm / s, and the upper punch continues to extrude downward. When the extrusion stroke has the last 10 mm left or the forming load reaches 90% of the capacity load of the pressure equipment, the extrusion rate drops to 0.6-0.7 mm / s until the die forging is formed. After the conical cylindrical die forging is formed, the pressure is maintained for 1.5-2.5 minutes.

[0011] In some embodiments, forging the ingot into a blank comprises: heating the ingot to 470-480° C. and keeping the heated ingot warm for a holding time of T ingot = 2.5-3.5 min / mm×D 铸锭 , where D 铸锭 is the ingot diameter, the final forging temperature of the billet is greater than or equal to 380°C; the ingot is subjected to four-pier and three-draw multi-directional forging on a pressure device, and after the multi-directional forging, it is subjected to punching, mandrel drawing, and hole expansion processes to make the billet into a hollow cylindrical billet.

[0012] According to another aspect of the present application, a die for a large-sized conical cylindrical die forging is also provided, which is used in a forming method for a large-sized conical cylindrical die forging, and includes: a lower die, an upper punch, and a second ejection mechanism and a first ejection mechanism inserted and arranged at the bottom of the lower die.

[0013] In some embodiments, the top of the first ejection mechanism is an ejection portion, the top of the second ejection mechanism is a lifting portion, the lifting portion is an annular disc, and the ejection portion is engaged in the lifting portion.

[0014] In some embodiments, a groove is provided at the bottom of the upper punch, the shape of the groove is adapted to the shape of the ejection portion, and the height of the ejection portion is greater than the sum of the height of the groove and the height of the lifting portion.

[0015] In some embodiments, the bottom diameter of the ejection portion is smaller than the inner diameter of the bottom surface of the conical cylindrical die forging after forming, so as to form an inner flange structure at the bottom of the conical cylindrical die forging.

[0016] In some embodiments, the mold further includes a punching plate, which is detachably connected to the top of the lower die and is used to prevent the die forging from moving upward together with the upper punch when the upper punch moves upward during demolding.

[0017] Compared with the prior art, the advantages and positive effects of this application are:

[0018] 1. This application effectively reduces the projected area and load requirements of the pressure equipment during the forming process by "expanding first and then extruding" the blank, which can reduce the load requirement by at least 27%.

[0019] 2. This application forms a conical cylindrical die forging with a bottom inner flange structure through a forming method and die design. This die forging has only an inner flange structure and no skin at the bottom, which can increase the utilization rate of the raw materials of the die forging by more than 8%.

[0020] 3. The present application provides a composite ejection mechanism consisting of a first ejection mechanism and a second ejection mechanism, so that the die forging can be smoothly demolded after being formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A method flow chart of Example 1 of the present application is shown.

[0023] Figure 2 A schematic diagram of the blank of Example 1 of the present application is shown.

[0024] Figure 3 A schematic cross-sectional view of the assembly of the blank and the forging die before forming in Example 1 of the present application is shown.

[0025] Figure 4 A schematic cross-sectional view of the assembly of the die forging and the forging die after forming in Example 1 of the present application is shown.

[0026] Figure 5 A schematic diagram of the die-holding phenomenon of the die forging in Example 1 of the present application is shown.

[0027] Figure 6 A schematic cross-sectional view of the die forging after forming in Example 1 of the present application is shown.

[0028] Figure 7 A schematic diagram of the projection area and load curve of the comparative forging of the present application are shown.

[0029] Figure 8 A schematic diagram of the projection area and load curve of the forging according to the embodiment of the present application is shown.

[0030] In the figure: 100, lower concave die; 200, upper convex die; 210, groove; 300, second ejection mechanism; 310, lifting part; 400, first ejection mechanism; 410, ejection part; 500, punching plate. DETAILED DESCRIPTION

[0031] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0032] The present application is further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] Embodiment 1:

[0034] Taking the forming of a 60mm thick aluminum alloy 2A14 conical cylindrical die forging as an example, a hydraulic press equipment of a domestic manufacturer is used as a die forging forming load pressure equipment to illustrate a forming method of a large-size conical cylindrical die forging in this application. Figure 1 As shown, the specific steps S100-S400 are as follows:

[0035] S100, using an ingot of Φ480×1035mm, the ingot is heated to 480℃, then kept warm for 25h, and after multi-directional forging with four piers and three draws on a pressure device, it is made into a billet through the processes of punching → mandrel drawing → hole expansion. The final forging temperature is 385℃ to form a cylindrical billet, such as Figure 2 As shown, the inner diameter of the bottom of the blank is φ580±1mm, the outer diameter of the bottom is φ750±1mm, the inner diameter of the top is φ650±1mm, the outer diameter of the top is φ850±1mm, the height of the blank is 800±1mm, and the radius of the outer diameter of the bottom of the blank is R25.

[0036] S200, heat the billet to 470℃, keep it warm for 150min, preheat the forging die to 420℃, assemble the billet and the forging die, the assembly section diagram of the billet and the forging die is shown in Figure 3 shown.

[0037] S300, using a forging die to form a conical cylindrical die forging with a bottom inner flange structure by means of "expansion and extrusion combination" of the blank.

[0038] In this embodiment, in the hole expansion forming stage in the "expansion and extrusion combination" method, the upper punch 200 moves downward at a rate of 4 mm / s, and the forging die is used to expand the hollow inner cavity of the billet toward the outside of the billet. When the extrusion stroke reaches 680 mm or the forming load exceeds the equipment capacity load of 4000 t, the outer wall of the billet gradually fits the inner wall of the lower concave die 100, the hole expansion ends, and the extrusion begins. The extrusion rate drops to 2 mm / s, and the extrusion continues. When the extrusion stroke remains for the last 10 mm or the forming load reaches the equipment capacity requirement of 5400 t, the extrusion rate is reduced to 0.6 mm / s until the die forging is completed (such as Figure 4 The figure shows the assembly cross-section diagram of the die forging and the forging die after forming. After the die forging is completed, the pressure is maintained for 2 minutes.

[0039] It should be noted that the "expansion" in the "expansion-extrusion combination" method refers to the process in which the hollow inner cavity of the blank is expanded toward the outside of the blank until the outer wall of the upper punch 200 gradually contacts and completely fits the inner wall of the blank; the "extrusion" refers to the process in which the upper punch 200 continues to press downward, and the upper punch 200 and the lower die 100 extrude the blank in both positive and negative directions, ultimately forming the conical cylindrical die forging with a bottom inner flange structure.

[0040] S400, forging demoulding.

[0041] In this embodiment, the demolding of the forging is to move the first ejector mechanism 400 upward to eject the upper punch 200, so that the upper punch 200 is separated from the forging, remove the punching plate, and then move the second ejector mechanism 300 upward to separate the forging from the lower die 100. As the first ejector mechanism 400 and the second ejector mechanism 300 continue to move upward, the first ejector mechanism 400, the second ejector mechanism 300 and the forging are ejected from the forging die together, and the forging forming process is terminated.

[0042] It should be noted that, in the process of moving the first ejection mechanism 400 upward to eject the upper punch 200, in order to prevent the demolding failure caused by the adhesion of the forging to the upper punch 200, a punching plate 500 is detachably connected to the top of the lower die 100. In the process of the upper punch 200 being ejected, the forging is clamped at the lower part of the punching plate 500, thereby ensuring that the upper punch 200 is ejected smoothly. After the upper punch 200 is ejected, the punching plate 500 is removed, and the demolding step of the forging is continued. Among them, the connection method between the punching plate 500 and the lower die 100 is a detachable connection. The specific detachable connection method is not limited in this application. For example, the detachable connection can be a bolt connection.

[0043] In this embodiment, in order to prevent Figure 5 The die forging has a "die-holding" phenomenon, and the first ejection mechanism 400 and the second ejection mechanism 300 are used together to enable the die forging to be smoothly demolded after being formed.

[0044] In this embodiment, the final forging specifications are as follows: Figure 6 As shown, the diameter of the hollow part in the bottom of the forging is φ580±2mm, the outer diameter of the top is φ1020±2mm, the height of the forging is 1010±2mm, the angle between the inner wall of the forging and the vertical direction is 8°, and the wall thickness of the forging is 60mm.

[0045] Comparative example: A 2A14 aluminum alloy conical cylindrical die forging with a wall thickness of 60 mm was manufactured using a solid rod extrusion method.

[0046] The projected area and load of the die forgings produced in Example 1 and the comparative example are compared. Figure 7 and Figure 8 The schematic diagrams of the projected areas and the load curves of the die forgings produced in the comparative example and embodiment 1 are shown respectively. Figure 7 - Figure 8 As shown, the projection area in the comparative example is the side wall and bottom surface of the die forging, and the projection area in Example 1 is only the side wall of the die forging; the actual load of the forming completion equipment in the comparative example is 8.61e+03, and the actual load of the forming completion equipment in Example 1 is 6.14e+03. Therefore, the die forging forming method of Example 1 can effectively reduce the projection area and load requirements.

[0047] Furthermore, three kinds of rotary forgings with tapers were compared, namely, free forging rectangular cross-section barrel forgings, free forging conical barrel forgings (small end with bottom, no flange structure), and die forging tapered shell forgings (method of Example 1, i.e., small end without bottom, bottom with flange structure), and then machined to manufacture the parts. As shown in Table 1, compared with the first two free forging schemes, die forging has the characteristics of good quality consistency, high performance margin, and fiber streamline distribution along the part contour; in addition, the die forging scheme saves at least 28.6% of the production cycle and more than 28% of the production cost compared with free forging, and the die forging scheme has a great advantage.

[0048] Table 1 Comparison of product quality and economy of three manufacturing schemes and conical cylindrical die forgings

[0049]

[0050] Embodiment 2:

[0051] like Figure 3-Figure 4As shown, in this embodiment, a die for a large-sized conical cylindrical die forging is provided, which is used in a forming method for a large-sized conical cylindrical die forging in Example 1, and includes: a lower die 100, an upper punch 200, and a second ejection mechanism 300 and a first ejection mechanism 400 inserted and arranged at the bottom of the lower die 100.

[0052] It should be noted that the lower concave die 100 and the second ejection mechanism 300, and the lower concave die 100 and the first ejection mechanism 400 are connected in a plug-in manner. In order to make the various parts relatively fixed during the forming process, a fixing device can also be added between the lower concave die 100 and the second ejection mechanism 300, and between the lower concave die 100 and the first ejection mechanism 400 when in use. Whether to add a fixing device is not restricted in this application.

[0053] In this embodiment, the top of the first ejection mechanism 400 is an ejection part 410, and the top of the second ejection mechanism 300 is a lifting part 310, which is in the shape of an annular disc, and the ejection part 410 is engaged in the lifting part 310; a groove 210 is arranged at the bottom of the upper punch 200, and the shape of the groove 210 is adapted to the shape of the lifting part 410, and the height of the ejection part 410 is greater than the sum of the height of the groove 210 and the height of the lifting part 310; the bottom surface diameter of the ejection part 410 is smaller than the inner diameter of the bottom surface of the conical cylindrical die forging after forming, and is used to form the bottom inner flange structure of the conical cylindrical die forging; the forging die also includes a punching tray 500, which is detachably connected to the top of the lower die 100, and is used to prevent the die forging from moving upward together with the upper punch 200 when the upper punch 200 moves upward during demolding.

[0054] It should be noted that, in the process of moving the first ejection mechanism 400 upward to eject the upper punch 200, in order to prevent the forging from adhering to the upper punch 200 and causing demoulding failure (such as Figure 5 As shown), a punching plate 500 is detachably connected to the top of the lower die 100. During the ejection of the upper punch 200, the forging is clamped at the lower part of the punching plate 500, thereby ensuring that the upper punch 200 is ejected smoothly. After the upper punch 200 is ejected, the punching plate 500 is removed, and then the demolding step of the forging is continued. The connection method between the punching plate 500 and the lower die 100 is a detachable connection. The application does not limit the specific detachable connection method. For example, the detachable connection can be a bolt connection.

[0055] The method for using a die for a large-sized conical cylindrical die forging in the present embodiment is as follows: the first ejector mechanism 400 is moved upward to eject the upper punch 200, so that the upper punch 200 is separated from the forging, the punching plate is removed, and then the second ejector mechanism 300 is moved upward to separate the forging from the lower die 100. As the first ejector mechanism 400 and the second ejector mechanism 300 continue to move upward, the first ejector mechanism 400, the second ejector mechanism 300 and the forging are ejected from the forging die together, and the forging die forging production process is terminated.

[0056] Through the above specific implementations, those skilled in the art can easily implement the present application. However, it should be understood that the present application is not limited to the above specific implementations. Based on the disclosed implementations, those skilled in the art can arbitrarily combine different technical features to achieve different technical solutions.

Claims

1. A forming method for a large-size conical cylindrical die forging, characterized in that: include: Forging the ingot into a billet, wherein the billet is a hollow cylindrical billet; Assembling the blank with a forging die; The forging die is used to expand the hollow inner cavity of the blank toward the outside of the blank, and then the inner and outer walls of the blank are compositely extruded to form a conical cylindrical die forging with a bottom inner flange structure.

2. The forming method of a large-size conical cylindrical die forging according to claim 1 is characterized in that: The step of assembling the blank and the forging die comprises: The blank is heated to 460-470°C and kept warm for a time of 1.5-2.0 min / mm×D. 坯料 , where D 坯料 is the effective thickness of the blank; Preheating the forging die to above 400° C. The blank is placed in the lower concave die (100) of the forging die, and the upper convex die (200) is placed just above the hollow cavity of the blank.

3. The forming method of a large-size conical cylindrical die forging according to claim 2, characterized in that: The expansion is a process in which, during the process of pressing the upper punch (200) downward using a pressure device, the hollow inner cavity of the blank is expanded toward the outside of the blank until the outer wall of the upper punch (200) gradually contacts and completely fits the inner wall of the blank; the composite extrusion is a process in which the upper punch (200) and the lower die (100) continue to press downward and extrude the blank in both positive and negative directions, ultimately forming the conical cylindrical die forging with a bottom inner flange structure; the final forging temperature after the composite extrusion is completed is greater than or equal to 370°C.

4. A forming method for a large-size conical cylindrical die forging according to claim 3, characterized in that: The initial extrusion rate of the composite extrusion is 3-5 mm / s. When the extrusion stroke reaches three-fifths of the inner cavity height of the conical cylindrical die forging or the forming load exceeds two-thirds of the capacity load of the pressure equipment, the extrusion rate drops to 1.6-2.2 mm / s, and the upper punch (200) continues to extrude downward. When the extrusion stroke has the last 10 mm left or the forming load reaches 90% of the capacity load of the pressure equipment, the extrusion rate drops to 0.6-0.7 mm / s until the die forging is formed. After the conical cylindrical die forging is formed, the pressure is maintained for 1.5-2.5 minutes.

5. The forming method of a large-size conical cylindrical die forging according to claim 1 is characterized in that: The step of forging the ingot into a blank comprises: The ingot is heated to 470-480°C and the heated ingot is kept warm for a holding time T 铸锭 =2.5~3.5min / mm×D 铸锭 , where D 铸锭 is the ingot diameter, and the final forging temperature of the billet is greater than or equal to 380°C; The ingot is subjected to four-pier and three-draw multi-directional forging on a pressure device, and then subjected to punching, mandrel drawing and hole expansion processes after the multi-directional forging, so that the billet is an annular cylindrical billet with a hollow interior.

6. A die for a large-sized tapered cylindrical die forging, used in a forming method for a large-sized tapered cylindrical die forging as claimed in any one of claims 1 to 5, characterized in that: include: A lower concave die (100), an upper convex die (200), and a second ejection mechanism (300) and a first ejection mechanism (400) which are plugged and arranged at the bottom of the lower concave die (100).

7. The die for a large-size conical cylindrical die forging according to claim 6, characterized in that: The top of the first ejection mechanism (400) is an ejection portion (410), and the top of the second ejection mechanism (300) is a lifting portion (310). The lifting portion (310) is in the shape of an annular disc, and the ejection portion (410) is engaged in the lifting portion (310).

8. The die for a large-size conical cylindrical die forging according to claim 7, characterized in that: A groove (210) is provided at the bottom of the upper punch (200), the shape of the groove (210) is adapted to the shape of the ejection portion (410), and the height of the ejection portion (410) is greater than the sum of the height of the groove (210) and the height of the lifting portion (310).

9. The die for a large-size conical cylindrical die forging according to claim 8, characterized in that: The bottom diameter of the ejection portion (410) is smaller than the inner diameter of the bottom of the conical cylindrical die forging after forming, and is used to form an inner flange structure at the bottom of the conical cylindrical die forging.

10. The die for a large-size conical cylindrical die forging according to claim 6, characterized in that: The die also includes a punching plate (500) which is detachably connected to the top of the lower die (100) and is used to prevent the die forging from moving upward together with the upper punch (200) when the upper punch (200) moves upward during demolding.

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