Die and method for segmented forging forming of large symmetrical double-hole frame forge piece

Abstract

The invention discloses a die and method for segmented forging forming of a large symmetrical double-hole frame forge piece, the die is composed of an upper die and a lower die, the upper die and the lower die are arranged in a butt joint mode, the butt joint faces of the upper die and the lower die are provided with an upper die cavity and a lower die cavity respectively, and the upper die cavity and the lower die cavity define a forming cavity; the cavity is provided with a transverse extension section, an edge section I and an edge section II. According to the die, flowing of materials around the ribs can be promoted, prefabrication forming is conducted on the forge piece through low forming load, arc-shaped concaves are prevented from occurring in the segmented staggered positions of the large-scale symmetrical double-hole forge piece, metal flow lines in the segmented staggered positions of the large-scale symmetrical double-hole forge piece are evenly distributed, and the forming quality is improved. And then the final forging shaping die is used for shaping and forming, and the problems of warping possibly occurring in segmented forming, incomplete filling of edge positions, forge piece size difference caused by transverse extension of blanks and the like are solved.

Description

Technical Field

[0001] The invention relates to the technical field of plastic forming of metal materials, and in particular to a die and a forming method for segmented forging of a large symmetrical double-hole frame forging. Background Art

[0002] The rapid development of the aviation industry has put forward higher requirements on the mechanical properties, service stability and bearing capacity of large components, which has led to the increasingly prominent development trend of large components towards integration, complexity and precision. Large symmetrical double-hole aluminum alloy forgings have broad application prospects in the fields of aviation, aerospace, etc. At present, the overall plastic forming methods of large symmetrical double-hole aluminum alloy forgings mainly include: pre-forging-final forging forming technology, multi-fire die forging forming technology and die forging local loading forming technology. However, these methods have many problems: (1) The use of pre-forging-final forging forming technology for the forming of large symmetrical double-hole forgings has problems such as large machining allowance, low material utilization rate, poor forming process stability, and uncontrollable deformation uniformity of forgings; (2) The basic steps of multi-fire die forging forming technology are to partially form the blank within the limit load, then trim, punch and heat the partially deformed blank, and then form it again within the limit load, repeating many times until the forging is fully formed; multi-fire die forging forming technology does not require the design and manufacture of pre-forging dies, and can only use one die to manufacture large forgings, but due to its lack of The method of controlling the forming fire times is not feasible, resulting in long production time, large die wear, and low material utilization rate. (3) The basic principle of the die forging local loading forming technology is to use an upper die divided into several sections and a lower die with the same length as the forging cavity to locally press the blank, and then achieve the overall die forging of large symmetrical double-hole aluminum alloy forgings by precisely controlling the position of applying the load on the blank. The die forging local loading forming technology can effectively reduce the forming load and solve the problem of insufficient forming capacity of the press. However, since its upper die usually adopts a rounded transition structure, it will cause arc depressions and uneven distribution of metal streamlines at the staggered positions of the segments of large symmetrical double-hole forgings. Especially when using the traditional pre-forging-final forging forming technology, due to the limited forging tonnage, a lot of material will be wasted and the forging forming cannot be carried out well. If the traditional segmented forming method is used for forging, multiple sets of dies will be required, and the material streamlines will be uneven and disordered in the segmented area. Therefore, the traditional pre-forging-final forging or segmented forming methods have problems such as large machining allowance, low material utilization, poor forming process stability, and uncontrollable deformation uniformity of forgings. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a die and forming method for the segmented forging of large symmetrical double-hole frame forgings, so as to solve the problems of the prior art in which the nominal pressure of the press for integral forging of large symmetrical double-hole aluminum alloy forgings is limited, and the metal streamlines at the staggered positions are unevenly distributed during the segmented forming of large symmetrical double-hole forgings.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A die for segmented forging of large symmetrical double-hole frame forgings, the die consisting of an upper die and a lower die, the upper and lower dies being arranged in opposition, and an upper die cavity and a lower die cavity being respectively provided on the opposing surfaces of the upper and lower dies, the upper die cavity and the lower die cavity enclosing a forming cavity; one end of the cavity is an open end, and the other end is a closed end; the cavity is provided with a transverse extension section, an edge section I and an edge section II; one end of the edge section I is connected to the open end, and the other end is connected to one end of the transverse extension section; one end of the edge section II is connected to the closed end, and the other end is connected to the other end of the transverse extension section; the cavity walls at both ends of the transverse extension section are convex toward the direction away from the interior of the cavity, and are formed along the distal end. A transition slope I is formed by obliquely extending in the direction of the lateral extension section, and the cavity wall between the transition slope I and the edge section II is convex in the direction away from the interior of the cavity to form a transition arc surface; the cavity wall near the closed end of the edge section II is obliquely extended in the direction away from the interior of the cavity to form a transition slope II, so that a chamfered transition structure is formed between the edge section II and the closed end; in the lateral extension section, the cavity wall of the lower mold cavity is convex in the direction of the upper mold cavity to form a lower boss, and the lower boss is a truncated cone structure; the cavity wall of the upper mold cavity is convex in the direction of the lower mold cavity to form an upper boss, and the upper boss is a truncated cone structure, and the side surface of the lower boss facing the upper boss is in contact with the side surface of the upper boss facing the lower boss.

[0006] Preferably, the angle between the transition slope II and the horizontal plane is 30°.

[0007] The present invention also provides a segmented forging method for a large symmetrical double-hole aluminum alloy forging. The segmented forging method for a large symmetrical double-hole aluminum alloy forging is performed using the above-mentioned die. The specific steps are as follows:

[0008] Step 1: Preheat the upper die and lower die of the segmented forging prefabricated die and install them on the workbench of the press respectively;

[0009] Step 2: placing the preheated metal blank into the cavity of the lower die, and sequentially performing the first segmented preforming process and the second segmented preforming process to obtain a large symmetrical double-hole aluminum alloy preform after segmented forming;

[0010] Step 3: Preheat the upper and lower dies of the final forging die and install them on the workbench of the press respectively;

[0011] Step 4: Place the aluminum alloy preform after the second segmented preforming process in step 2 into the lower mold cavity of the final forging shaping die, and perform shaping and deformation on it using a press to obtain the symmetrical double-hole aluminum alloy forging.

[0012] Preferably, in step 1, the upper die and the lower die of the segmented forging prefabricated die are preheated to 400-420°C.

[0013] Preferably, in step 2, the specific process of the first segmented preforming process is as follows:

[0014] The press drives the segmented forging prefabricated upper die to move downward in the vertical direction to perform the first segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

[0015] Preferably, in step 2, after the first segmented pre-forming is completed, the metal blank is rotated 180° in the horizontal direction and placed at the second segmented forming position to ensure that the circular hole portion on the metal blank after the first segmented forming is not within the pressing range of the segmented forging preform mold for the second segmented forming.

[0016] Preferably, in step 2, the specific process of the second segmented preforming process is as follows:

[0017] The press drives the segmented forging prefabricated upper die to move downward in the vertical direction for the second segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

[0018] Preferably, in step 3, the upper die and the lower die of the final forging and shaping die are preheated to 400-420°C.

[0019] Preferably, in step 3, the press drives the upper die of the final forging shaping die to move downward in the vertical direction for shaping and deformation; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 5 mm set in the forming process.

[0020] Preferably, the loads of the first segmented preforming process, the second segmented preforming process and the final forging and shaping process are all less than the nominal pressure of the press.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the prior art, when performing integral forging of double-hole forgings, problems such as folding and streamline disorder are easily generated due to poor flow. The method described in the present invention divides the pre-forging into two steps. The double-hole forging is partially formed in advance through the first segmented pre-forming, and the preliminary overall forming is completed through the second segmented pre-forming. Combined with the reduced deformation resistance of the preheated mold, the streamline uniformity of the double-hole forging is improved and the occurrence of defects is reduced. At the same time, the prior art generally believes that the forging of large forgings must be matched with a press of the same tonnage for forming. However, the method described in the present invention can reduce the load required for a single deformation and reduce the dependence on large presses. The overall force is decomposed into local gradual loading through segmented deformation. Each deformation only needs to overcome the resistance of part of the blank, reducing the pressure required per unit time and significantly reducing equipment investment. Moreover, the two segmented deformations allow the metal to flow gradually, avoiding local excessive stretching or extrusion. At the same time, preheating the mold can reduce brittle cracks caused by rapid cooling of the blank.

[0023] 2. The method of the present invention adopts a segmented forging forming method, so it is not required to fill the cavity during the first forming. Compared with the traditional pre-forging-final forging forming method, the thickness of the sheet material used in the method of the present invention can be significantly reduced. This thickness reduction directly reduces the initial input of raw materials; more importantly, since the sheet material will be extended in the direction of the lateral extension section during the segmented forming process, the lateral length of the sheet material can be further shortened, and ultimately the overall size of the sheet material is greatly shortened, further reducing the amount of material used; the traditional pre-forging-final forging forming method has an overall material utilization rate of only 47.44%, while the method of the present invention has an overall material utilization rate of 71.2%, which means that when producing large symmetrical double-hole frame forgings of the same quantity and specifications, the method of the present invention can more efficiently utilize raw materials, reduce a large amount of material waste, and also reduce the energy consumption and cost of subsequent material handling, processing and other links.

[0024] 3. The present invention extends the right ends of the upper and lower dies of the segmented forging prefabricated mold to fully fit the forging structure design without designing rounded corners. At the same time, a boss structure is designed at the position of the inner circular hole to promote the flow of material around the ribs. A lower forming load is used to prefabricate the forging to avoid arc-shaped depressions in the segmented staggered positions of large symmetrical double-hole forgings, so that the metal streamlines at the segmented staggered positions of large symmetrical double-hole forgings are evenly distributed, and then the final forging is shaped through the final forging shaping mold to solve the problems of warping, incomplete filling of edge positions, and size differences of forgings caused by lateral extension of the billet that may occur in segmented forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the die for segmented forging of the large symmetrical double-hole frame forging according to the present invention.

[0026] Figure 2 It is a schematic diagram of the segmented forging process of the present invention.

[0027] Figure 3 This is a comparison chart of the blank size used in Comparative Example 1 and the blank size used in Example 1.

[0028] Figure 4 Load diagram for the forming process of Comparative Example 1.

[0029] Figure 5 This is the load diagram of the forming process of Example 1.

[0030] Figure 6 This is a metal streamline diagram of the middle cross section in the width direction of the formed forging obtained by forging using the method of the present invention in Example 1.

[0031] In the figure: upper die 1, lower die 2, open end 3, closed end 4, transverse extension section 5, edge section I 6, edge section II 7, transition slope I 8, transition arc surface 9, transition slope II 10, lower boss 11, upper boss 12. DETAILED DESCRIPTION

[0032] The present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments derived by persons of ordinary skill in the art based on the present invention are within the scope of protection of the present invention.

[0033] Unless otherwise indicated in specific cases, the numerical ranges listed herein include the upper and lower limits, and all integers and fractions within the range, and are not limited to the specific values ​​listed when defining the range.

[0034] 1. A die for segmented forging of large symmetrical double-hole frame forgings

[0035] The mold of the present invention is composed of an upper mold 1 and a lower mold 2, and the structure is as follows Figure 1As shown, the mold consists of an upper mold 1 and a lower mold 2, and the upper mold and the lower mold are arranged in abutment with each other, and an upper mold cavity and a lower mold cavity are respectively provided on the mating surfaces of the upper mold and the lower mold, and the upper mold cavity and the lower mold cavity surround a molding cavity; one end of the cavity is an open end 3, and the other end is a closed end 4; the cavity is provided with a transverse extension section 5, an edge section I 6 and an edge section II 7; one end of the edge section I is connected with the open end, and the other end is connected with one end of the transverse extension section; one end of the edge section II is connected with the closed end, and the other end is connected with the other end of the transverse extension section; the cavity walls at both ends of the transverse extension section bulge in the direction away from the interior of the cavity, and extend obliquely in the direction away from the transverse extension section to form a transition inclined surface I 8, and the cavity wall between the transition inclined surface I and the edge section II bulges in the direction away from the interior of the cavity to form a transition arc surface 9; the cavity wall near the closed end of the edge section II is obliquely extended in the direction away from the interior of the cavity to form a transition inclined surface II 10, so that a chamfered transition structure is formed between the edge section II and the closed end; in the transverse extension section, the cavity wall of the lower mold cavity protrudes toward the upper mold cavity to form a lower boss 11, and the lower boss is a truncated cone-shaped structure; the cavity wall of the upper mold cavity protrudes toward the lower mold cavity to form an upper boss 12, and the upper boss is a truncated cone-shaped structure, and the side surface of the lower boss facing the upper boss is in contact with the side surface of the upper boss facing the lower boss.

[0036] When studying the molds of the prior art, the present invention found that since the upper mold of the existing pre-forging mold usually adopts a rounded transition structure, it will cause arc-shaped depressions and uneven distribution of metal streamlines at the segmented interlaced positions of large symmetrical double-hole forgings. Based on this, the present invention improves the structure of the prefabricated mold for segmented forging, further extends the length of the transverse extension section in the cavity, and extends the transverse extension section near the closed end in the direction away from the transverse extension section, so that it completely fits the forging structure design without designing rounded corners; at the same time, the upper and lower boss structures are designed at the location of the inner circular hole, which can promote the flow of material around the upper and lower bosses, and use a lower forming load to preform the forging, avoiding the arc-shaped depressions at the segmented interlaced positions of large symmetrical double-hole forgings, so that the metal streamlines at the segmented interlaced positions of large symmetrical double-hole forgings are evenly distributed. Then, the final forging shaping mold is used for shaping to solve the problems of warping, incomplete filling of the edge position, and size differences of forgings caused by the lateral extension of the billet that may occur in segmented forming.

[0037] In some embodiments of the present invention, the angles between the transition slope I, the transition slope II and the horizontal plane are both 30°.

[0038] In some embodiments of the present invention, Figure 1 The final forging and shaping die used in the intermediate final forming is a conventional die in the prior art.

[0039] In some embodiments of the present invention, the length of the transverse extension section is 80-130 mm, the height of the transition slope I in the vertical direction is 35-55 mm, the length of the transition slope I in the horizontal direction is 50-60 mm, and the length of the hypotenuse of the transition slope I is 20-30 mm.

[0040] 2. A Segmented Forging Method for Large Symmetrical Double-Hole Aluminum Alloy Forgings

[0041] The above die is used to perform segmented forging of a large symmetrical double-hole aluminum alloy forging. The specific steps are as follows:

[0042] Step 1: Preheat the upper die and lower die of the segmented forging prefabricated die and install them on the workbench of the press respectively;

[0043] Step 2: placing the preheated metal blank into the cavity of the lower die, and sequentially performing the first segmented preforming process and the second segmented preforming process to obtain a large symmetrical double-hole aluminum alloy preform after segmented forming;

[0044] Step 3: Preheat the upper and lower dies of the final forging die and install them on the workbench of the press respectively;

[0045] Step 4: Place the aluminum alloy preform after the second segmented preforming process in step 2 into the lower mold cavity of the final forging shaping die, and perform shaping and deformation on it using a press to obtain the symmetrical double-hole aluminum alloy forging.

[0046] In some embodiments of the present invention, in step 1, the upper die and the lower die of the segmented forging preform die are preheated to 400-420°C.

[0047] In some embodiments of the present invention, in step 2, the specific process of the first segmented preforming process is as follows:

[0048] The press drives the segmented forging prefabricated upper die to move downward in the vertical direction to perform the first segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

[0049] In some embodiments of the present invention, in step 2, after the first segmented pre-forming is completed, the metal blank is rotated 180° in the horizontal direction and placed at the second segmented forming position to ensure that the circular hole portion on the metal blank after the first segmented forming is not within the pressing range of the segmented forging preform mold for the second segmented forming.

[0050] In some embodiments of the present invention, in step 2, the specific process of the second segmented preforming process is as follows:

[0051] The press drives the segmented forging prefabricated upper die to move downward in the vertical direction for the second segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

[0052] In some embodiments of the present invention, in step 3, the upper die and the lower die of the final forging and shaping die are preheated to 400-420°C.

[0053] In some embodiments of the present invention, in step 3, the press drives the upper die of the final forging shaping die to move downward in the vertical direction for shaping deformation; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 5 mm set by the forming process.

[0054] In some embodiments of the present invention, the loads of the first segmented preforming process, the second segmented preforming process, and the final forging and shaping process are all less than the nominal pressure of the press.

[0055] 3. Examples and Comparative Examples

[0056] Example 1: Taking 20 series aviation high-strength and toughness aluminum alloy as an example

[0057] Step 1: Preheat the upper and lower dies of the segmented forging die to 400°C and install them on the upper and lower working surfaces of the press;

[0058] Step 2: Forming method:

[0059] A. Place the heated metal blank (the length of the metal blank is the transverse length of the final forging die minus the length of the transverse extension section in the prefabricated die) into the cavity of the prefabricated lower die for segmented forging;

[0060] B. The press drives the upper die of the segmented forging forming prefabricated to move downward to perform the first segmented preforming, pressing to the underpressure set by the forming process of 8mm; wherein, the initial forging temperature is 450℃ and the pressing speed is 5mm / s.

[0061] C. After the first segmented preforming is completed, the press returns to lift the segmented forging prefabricated upper die, then operates the manipulator to clamp the metal billet, rotate it 180°, and move it forward to the second segmented position. The second segmented position refers to the position where the slope edge of the circular hole after the first segmented forming is tangent to the right edge of the pre-forging die, ensuring that the circular hole after the first forming is not within the pressing range of the segmented forging prefabricated die;

[0062] D. The press drives the upper die of the segmented forging forming prefabricated to move downward to perform the second segmented preforming, pressing to the underpressure of 8mm set in the forming process; wherein, the initial forging temperature is 450℃ and the pressing speed is 5mm / s.

[0063] E. After the second segmented preforming is completed, the press returns to lift the segmented forging prefabricated upper die, and the formed large symmetrical double-hole preform is taken out from the cavity of the segmented forging prefabricated lower die;

[0064] Step 3: Final Forging: Preheat the upper and lower dies of the final forging die to 400°C. Place the large symmetrical double-hole preform after segmented forming into the cavity of the final forging die. The press drives the final forging die downward to perform shaping and deformation, pressing to the reduction set by the forming process. The initial forging temperature is 410°C, the pressing speed is 5mm / s, and the pressure is pressed to the underpressure set by the forming process of 5mm. The press lifts the final forging die in the return stroke and removes the formed large symmetrical double-hole forging from the cavity of the final forging die.

[0065] During the forming process of Example 1, the nominal pressure of the press is 80,000 tons, and the maximum load that the press can provide is 800MN. The load during the entire forming process is relatively low, basically not exceeding 547MN, and the maximum forming load reaches 672MN.

[0066] Comparative Example 1

[0067] The existing pre-forging-final forging forming method was adopted. The press used in Comparative Example 1 was the same as that used in Example 1, and the metal forging samples made of the same material as that in Example 1 were processed.

[0068] The material utilization rate of the products obtained by processing Example 1 and Comparative Example 1 was calculated. The length, width and four-corner dimensions of the materials used in Example 1 and Comparative Example 1 were the same, but the thickness of the materials used in Example 1 and Comparative Example 1 was different to meet the processing requirements. Therefore, the material utilization rate = the weight of the material after processing (the material after processing will cut off the defects caused by processing) / the weight of the material before processing × 100%. Figure 3 As shown, in Comparative Example 1, in order to better fill the pre-forging die cavity, the thickness of the sheet metal needs to be increased to make up for the insufficient load of the current equipment. The sheet metal thickness selected is 180 mm, and the overall material utilization rate is 47.44%, which is a low material utilization rate. In Example 1, the large symmetrical double-hole frame forging is formed without requiring the die cavity to be fully filled during the first forming process. The sheet metal thickness selected is slightly lower than that of Comparative Example 1, which is 170 mm. Since the sheet metal will be extended in the transverse direction during segmented forming, the sheet metal length can be reduced by 480 mm on one side in the transverse length relative to the sheet metal formed in Comparative Example 1 based on the extended length. The overall material utilization rate is 71.2%, which is a high material utilization rate.

[0069] like Figure 4As shown, when comparative example 1 adopts the pre-forging-final forging forming method for forming treatment, due to the large size of the material, theoretically a press with a higher nominal pressure is required for processing. However, the press used in Example 1 cannot directly process the forgings using the pre-forging-final forging forming method, so comparative example 1 can only use 1 / 4 of the forgings for simulation calculations, and then actually produce; from the simulation results, the theoretical maximum load for processing 1 / 4 of the forgings reaches 192MN. If the forgings as a whole are to be directly formed, the theoretical load must be at least above 768NM, even far exceeding the maximum load that the press can provide. This is also the reason why comparative example 1 cannot use the pre-forging-final forging forming method to process large symmetrical double-hole forgings, and a press with a higher load is required. Moreover, even if comparative example 1 is divided into parts for processing, it is easy to cause mold collapse, wear and other losses, thereby reducing the life of the mold. As shown in the figure, Figure 5 As shown, Example 1 uses the method of the present invention to form a large symmetrical double-hole frame forging. The load during the entire forming process is relatively low, and the maximum forming load reaches 672MN.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A die for forming a large symmetrical double-hole frame forging piece by segmented forging, the die comprising an upper die (1) and a lower die (2), the upper die and the lower die being arranged in a mating relationship, and an upper die cavity and a lower die cavity being respectively provided on the mating surfaces of the upper die and the lower die, the upper die cavity and the lower die cavity enclosing a forming cavity; characterized in that: One end of the mold cavity is an open end (3), and the other end is a closed end (4); the mold cavity is provided with a transverse extension section (5), an edge section I (6) and an edge section II (7); one end of the edge section I is connected to the open end, and the other end thereof is connected to one end of the transverse extension section; one end of the edge section II is connected to the closed end, and the other end thereof is connected to the other end of the transverse extension section; the cavity walls at both ends of the transverse extension section are convex in a direction away from the interior of the mold cavity, and extend obliquely in a direction away from the transverse extension section to form a transition slope I (8), and the mold cavity between the transition slope I and the edge section II is The wall is convex in the direction away from the interior of the cavity to form a transition arc surface (9); the cavity wall near the closed end of the edge section II is inclined and extended in the direction away from the interior of the cavity to form a transition inclined surface II (10), so that a chamfered transition structure is formed between the edge section II and the closed end; in the transverse extension section, the cavity wall of the lower mold cavity is convex in the direction of the upper mold cavity to form a lower boss (11), and the lower boss is a truncated cone structure; the cavity wall of the upper mold cavity is convex in the direction of the lower mold cavity to form an upper boss (12), and the upper boss is a truncated cone structure, and the side surface of the lower boss facing the upper boss is in contact with the side surface of the upper boss facing the lower boss.

2. The mold according to claim 1, characterized in that: The included angle between the transition slope II and the horizontal plane is 30°.

3. A segmented forging method for a large symmetrical double-hole aluminum alloy forging, characterized in that: The die according to any one of claims 1 to 2 is used to perform segmented forging of a large symmetrical double-hole aluminum alloy forging, and the specific steps are as follows: Step 1: Preheat the upper die and lower die of the segmented forging prefabricated die and install them on the workbench of the press respectively; Step 2: placing the preheated metal blank into the cavity of the lower die, and sequentially performing the first segmented preforming process and the second segmented preforming process to obtain a large symmetrical double-hole aluminum alloy preform after segmented forming; Step 3: Preheat the upper and lower dies of the final forging die and install them on the workbench of the press respectively; Step 4: Place the aluminum alloy preform after the second segmented preforming process in step 2 into the lower mold cavity of the final forging shaping die, and perform shaping and deformation on it using a press to obtain the symmetrical double-hole aluminum alloy forging.

4. The segmented forging method according to claim 3, characterized in that: In step 1, the upper die and the lower die of the segmented forging prefabricated die are preheated to 400-420°C.

5. The segmented forging method according to claim 3, characterized in that: In step 2, the specific process of the first segmented preforming process is as follows: The press drives the segmented forging prefabricated upper die to move downward in the vertical direction to perform the first segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

6. The segmented forging method according to claim 3, characterized in that: In step 2, after the first segmented pre-forming is completed, the metal blank is rotated 180° in the horizontal direction and placed at the second segmented forming position to ensure that the circular hole portion on the metal blank after the first segmented forming is not within the pressing range of the segmented forging prefabricated mold for the second segmented forming.

7. The segmented forging method according to claim 3, characterized in that: In step 2, the specific process of the second segmented preforming process is as follows: The press drives the segmented forging prefabricated upper die to move downward in the vertical direction for the second segmented preforming; wherein, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 8 mm set in the forming process.

8. The segmented forging method according to claim 3, characterized in that: In step 3, the upper die and the lower die of the final forging and shaping die are preheated to 400-420°C.

9. The segmented forging method according to claim 3, characterized in that: In step 3, the press drives the upper die of the final forging shaping die to move vertically downward to perform shaping and deformation; Among them, the initial forging temperature is 410-470°C, the pressing speed is 2-5 mm / s, and the pressing is performed to the underpressure of 5 mm set in the forming process.

10. The segmented forging method according to claim 3, characterized in that: The loads of the first segmented preforming treatment, the second segmented preforming treatment and the final forging and shaping are all less than the nominal pressure of the press.

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