Forging method of aluminum alloy frame shaped like Chinese character'hui '

Abstract

The invention relates to a forging method of an aluminum alloy rectangular-ambulatory-plane frame, which comprises the following steps: selecting a cast ingot or a bar billet as a raw material, performing three-way upsetting and pulling modification to prepare a square transition billet with a square plate and a concave step, and positioning the concave step between the two ends of the square plate in the length direction; a flat anvil is used for conducting multi-pass forging on the inwards-concave steps, the two ends of the square plate are widened to the matched size after each pass of forging is completed, the square transition blank is flattened to form a square plate blank, and inwards-concave grooves are formed in the center positions of the plate faces of the two sides of the square plate blank; a pre-forging die is used for pre-forging the square plate blank, so that the square plate blank is shaped into a frame type pre-forged piece with a wad in the center; and a finish forging die is used for conducting finish forging on the frame type pre-forged piece, so that the frame type pre-forged piece is forged into a frame finish forged piece shaped like a Chinese character'hui '. According to the method, concave grooves are formed in the center positions of the two side plate surfaces of the square plate blank during pre-forging, so that the square plate blank can be formed into a hollow-square-shaped frame final forging piece only through one-time pre-forging shaping and final forging.

Description

Technical Field

[0001] This invention belongs to the field of materials processing technology, and specifically relates to a forging method for an aluminum alloy "U"-shaped frame. Background Technology

[0002] Helicopter fuselages extensively utilize aluminum alloy "U"-shaped frame structures. These frames have an outer length exceeding 4 meters and a width exceeding 2.5 meters, while their inner length exceeds 3 meters and their width exceeds 2 meters, classifying them as extra-large frames. Historically, these frames have been manufactured using sheet metal, a process that consumes a significant amount of material. To save materials, production of these frames has gradually shifted towards die forging, especially for mass production, where die forging offers greater cost savings.

[0003] In existing technologies, the die forging forming methods for extra-large aluminum alloy "U"-shaped frames mostly involve the gradual forming of slabs or bar billets through multiple forging stages using blanking dies, pre-forging dies, and final forging dies. This process takes a long time and is a significant waste of die forging equipment resources. Moreover, the multiple forging stages can easily affect the final forming effect, resulting in a high scrap rate in the final forging process. Summary of the Invention

[0004] This invention provides a forging method for an aluminum alloy "U"-shaped frame, which solves the technical problem that existing die forging methods for extra-large aluminum alloy "U"-shaped frames require multiple pre-forging and final forging processes to achieve the final shape.

[0005] This invention is achieved through the following technical solution: a forging method for an aluminum alloy "U"-shaped frame, comprising:

[0006] Step 1: Select ingots or billets as raw materials, and after three-dimensional upsetting and elongation modification, prepare a square transition billet with a square plate and a concave step, wherein the concave step is located between the two ends of the square plate in the length direction.

[0007] Step 2: Use a flat anvil to forge the concave steps in multiple passes, and after each forging pass, widen both ends of the square plate to the matching size so that the square transition billet is flattened to form a square plate blank, and a concave groove is formed at the center of both sides of the square plate blank.

[0008] Step 3: Use a pre-forging die to pre-forge the square slab to shape it into a frame-like pre-forged part with a connected skin at the center;

[0009] Step 4: Use a final forging die to perform final forging on the frame-type pre-forging part, so that the frame-type pre-forging part is forged into a "U"-shaped frame final forging part.

[0010] Furthermore, in order to better realize the present invention, the lower part of the flat anvil is a truncated square pyramid with a larger upper part and a smaller lower part, and the bottom edge of the flat anvil is provided with rounded corners.

[0011] Furthermore, in order to better realize the present invention, the angle of the cone surface of the truncated pyramid is less than or equal to 30°, and the radius of the fillet at the bottom edge of the anvil is greater than 50mm.

[0012] Furthermore, in order to better realize the present invention, in step 2, a solid part is formed between the bottom of the grooves on both sides of the square blank, the thickness of the solid part is less than or equal to 40mm, and a transition slope and a transition fillet are provided in the transition area between the solid part and the square blank, the angle between the transition slope and the parting surface is less than or equal to 30°, and the radius of the transition fillet is greater than 50mm.

[0013] Furthermore, in order to better realize the present invention, the concave step is flush with the square plate in the width direction and the concave step is located at the center of the square plate in the length direction.

[0014] Furthermore, in order to better realize the present invention, the outer dimensions of the aluminum alloy "U"-shaped frame are at least 4m in length and at least 2.5m in width, and the inner dimensions are at least 3m in length and at least 2m in width.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The forging method for an aluminum alloy "U"-shaped frame provided by this invention first selects an ingot or billet as raw material, and after three-dimensional upsetting and elongation modification, prepares a square transition billet with a square plate and concave steps. The concave steps are located between the two ends of the square plate in the length direction. Then, the concave steps are forged in multiple passes using a flat anvil. After each forging pass, the two ends of the square plate in the length direction are widened to a matching size so that the square transition billet is flattened to form a square plate. Concave grooves are formed at the center of both sides of the square plate. Then, a pre-forging die is used to pre-forge and shape the square plate to form a frame-like pre-forging part with a connected skin in the center. Finally, a final forging die is used to forge the frame-like pre-forging part to form a "U"-shaped frame final forging part.

[0017] The method provided by the present invention first uses a flat anvil to forge the square transition blank in multiple passes before pre-forging, so that concave grooves are formed at the central positions of both side plates of the square blank during pre-forging. In this way, the above-mentioned square blank only needs to be pre-forged and shaped once and then finally forged to form a "return" shaped frame final forging. Compared with the existing method of directly pre-forging using a flat plate, the method provided by the present invention can reduce multiple pre-forging operations in multiple heats. This can not only reduce the occupation time of the die forging equipment, but also reduce the final forming effect on the forging and improve the yield rate of the final forged product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 is a flowchart of the forging method of the aluminum alloy "return" shaped frame provided by the embodiment of the present invention;

[0020] Figure 2 is a schematic structural diagram of the square transition blank in the embodiment of the present invention;

[0021] Figure 3 is a schematic structural diagram of the flat anvil used in the embodiment of the present invention;

[0022] Figure 4 is a schematic structural diagram of the square blank in the embodiment of the present invention;

[0023] Figure 5 is a schematic structural diagram of the frame pre-forged part in the embodiment of the present invention;

[0024] Figure 6 is the structure of the "return" shaped frame final forging in the embodiment of the present invention;

[0025] Figure 7 is a schematic front view structure diagram when using a flat anvil to forge the square transition blank in the embodiment of the present invention;

[0026] Figure 8 is a schematic top view structure diagram when using a flat anvil to forge the square transition blank in the embodiment of the present invention.

[0027] In the figure:

[0028] 100-Square transition billet, 110-Square plate, 120-Concave step, 200-Flat anvil, 210-Frustum of a square pyramid, 220-Rounded corner, 300-Square slab, 310-Groove, 320-Transition slope, 330-Transition rounded corner, 400-Frame-type pre-forging, 500-"U"-shaped frame final forging. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] Example:

[0031] The forging method for an aluminum alloy "U"-shaped frame provided in this embodiment is used to forge extra-large aluminum alloy "U"-shaped frames. The extra-large aluminum alloy "U"-shaped frame has an outer dimension of at least 4m in length and at least 2.5m in width, and an inner dimension of at least 3m in length and at least 2m in width. The method is as follows: Figure 1 As shown, it includes the following steps:

[0032] Step 1: Select ingots or billets as raw materials, and through three-dimensional upsetting and elongation modification, prepare a square transition billet 100 with a square plate 110 and an inwardly recessed step 120 (specifically as follows). Figure 2 As shown, the concave step 120 is located between the two ends of the square plate in the length direction. Optionally, the concave step 120 is flush with the square plate 110 in the width direction and located at the center of the square plate 110 in the length direction. It is worth noting that the square transition blank 100 is a plate material that is shaped like an "I-beam", and the concave step can be understood as the "web" of the "I-beam".

[0033] Step 2: Use as follows Figure 3 The flat anvil, as shown, forges the aforementioned concave step 120 in more than 200 passes, and after each pass, widens the two ends of the square plate 110 in the length direction to a matching size, so that the square transition blank 100 is flattened to form a square plate blank 300 (specifically as shown). Figure 4 As shown in the figure, recessed grooves 310 are formed at the center of both sides of the square slab 300. Forging with a flat anvil 200 can be completed with the aid of a press, without the need for die forging equipment.

[0034] In addition, the grooves 310 on both sides of the square slab 300 are the same. Specifically, during forging, two flat anvils 200 are used to simultaneously forge the middle positions of the two sides of the concave step 120 (specifically as follows). Figure 7 and Figure 8 As shown in the diagram, a solid portion is formed between the grooves 310 on both sides of the square slab 300. The thickness of the solid portion is less than or equal to 40 mm, for example, 40 mm, 35 mm, or 30 mm. A transition slope 320 and a transition fillet 330 are provided in the transition area between the solid portion and the square slab 300. It is easy to understand that the solid portion is located at the center position in the thickness direction of the square slab. The angle between the transition slope 320 and the parting surface is less than or equal to 30°, specifically, the angle between the transition slope 320 and the parting surface is 30°, 35°, or 40°. The radius of the transition fillet 330 is greater than 50 mm, specifically, the radius of the transition fillet 330 is 55 mm, 60 mm, or 65 mm.

[0035] Optionally, in this embodiment, the lower part of the flat anvil 200 is a frustum 210 with a larger upper part and a smaller lower part. That is, the working section of the flat anvil 200 is a frustum 210, and the bottom edge of the flat anvil 200 is provided with a rounded corner 220. In this way, when the flat anvil 200 is used to forge the square transition blank 100, the metal can be better allowed to flow in all directions (in fact, most of the metal during forging flows towards the concave steps 120 on both sides in the width direction), and finally the groove 310 is formed on the square blank 300. Specifically, the angle of the cone surface of the frustum 210 is less than or equal to 30°, for example, the angle of the cone surface of the frustum 210 is 30°, 25°, or 20°, etc. The radius of the fillet 220 at the bottom edge of the aforementioned flat anvil 200 is greater than 50mm. Optionally, the radius of the fillet 220 at the bottom edge of the aforementioned flat anvil 200 is 55mm, 60mm, or 65mm, etc.

[0036] Step 3: Use a pre-forging die to pre-forge the square slab 300, so that the square slab 300 is shaped into a frame-like pre-forged part 400 with a connected skin at the center (specifically as shown in the figure). Figure 5 (As shown).

[0037] Step 4: Use a final forging die to perform final forging on the frame-type pre-forging part 400, so that the frame-type pre-forging part 400 is forged into a "U"-shaped frame final forging part 500 (specifically as follows). Figure 6 (As shown).

[0038] It should be noted that the pre-forging and final forging in this method are the same as in existing technologies, so they will not be described in detail here.

[0039] Through the above steps, the method provided in this embodiment uses a flat anvil to forge the square transition billet 100 more than 200 times before pre-forging, so that the center positions of both sides of the square slab 300 during pre-forging are formed with concave grooves 310. In this way, the square slab 300 only needs to undergo one pre-forging shaping and final forging to be formed into a "U"-shaped frame final forging part 500. Compared with the existing method of directly pre-forging with a flat plate, the method provided by this invention can reduce the number of pre-forging passes, which can not only reduce the time occupied by the forging equipment, but also reduce the impact on the final forming effect of the forging and improve the yield of the final forging.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A forging method for an aluminum alloy "U"-shaped frame, characterized in that, include: Step 1: Select ingots or billets as raw materials, and after three-dimensional upsetting and elongation modification, prepare a square transition billet (100) with a square plate (110) and a concave step (120), wherein the concave step (120) is located between the two ends of the square plate (110) in the length direction. Step 2: Use a flat anvil (200) to forge the concave step (120) in multiple passes, and after each forging pass, widen both ends of the square plate (110) to the matching size so that the square transition blank (100) is flattened to form a square plate blank (300), and a concave groove (310) is formed at the center of both sides of the square plate blank (300). Step 3: Use a pre-forging die to pre-forge the square slab (300) so that the square slab (300) is shaped into a frame-like pre-forging part (400) with a connected skin at the center; Step 4: Use a final forging die to perform final forging on the frame-type pre-forging (400) so that the frame-type pre-forging (400) is forged into a "U"-shaped frame final forging (500).

2. The forging method of the aluminum alloy "U"-shaped frame according to claim 1, characterized in that: The lower part of the flat anvil (200) is a truncated square pyramid (210) with a larger top and a smaller bottom, and the bottom edge of the flat anvil (200) is provided with a rounded corner (220).

3. The forging method of the aluminum alloy "U"-shaped frame according to claim 2, characterized in that: The angle of the cone surface of the truncated pyramid (210) is less than or equal to 30°, and the radius of the fillet (220) at the bottom edge of the anvil (200) is greater than 50 mm.

4. The forging method of the aluminum alloy "U"-shaped frame according to claim 2, characterized in that: In step 2, a solid part is formed between the bottom of the grooves (310) on both sides of the square blank (300). The thickness of the solid part is less than or equal to 40 mm. A transition slope (320) and a transition fillet (330) are provided in the transition area between the solid part and the square blank (300). The angle between the transition slope (320) and the parting surface is less than or equal to 30°. The radius of the transition fillet (330) is greater than 50 mm.

5. The forging method of the aluminum alloy "U"-shaped frame according to claim 1, characterized in that: The concave step (120) is flush with the square plate (110) in the width direction and is located at the center of the square plate (110) in the length direction.

6. The forging method of the aluminum alloy "U"-shaped frame according to any one of claims 1-5, characterized in that: The outer dimensions of the aluminum alloy "U"-shaped frame are at least 4m in length and at least 2.5m in width, and the inner dimensions are at least 3m in length and at least 2m in width.

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