Uniform deformation control process for Ti65 alloy air inlet cap forge piece

Abstract

The invention relates to the technical field of air inlet cap hood forming, in particular to a Ti65 alloy air inlet cap hood forge piece uniform deformation control process which comprises the following steps: firstly, preparing an original blank with a specific fillet characteristic and a bevel edge positioning characteristic; then forming through two-stage hot die forging: pre-forging at the temperature of 990-1010 DEG C to obtain a pre-forged blank with a bottom trapezoidal bulge, a conical inclined surface and a groove; and finally, carrying out finish forging at 1000-1030 DEG C to obtain a final forge piece. Through the optimization design of the shape of the pre-forged blank, the deformation amount of the conical thin-wall section is transferred to the small-diameter solid bottom, the overall coordinated and uniform deformation of the forged piece is achieved, the problems of surface cracking and uneven structure are effectively solved, the forming load is reduced from 14000 tons to about 7000 tons, and the service life of a die is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air inlet cap forming, and particularly relates to a Ti65 alloy air inlet cap forging uniform deformation control process. BACKGROUND

[0002] The air inlet cap is a key component of an aero-engine, and its main function is to prevent foreign matter from entering the engine and to regulate and pre-compress the air inlet airflow. The structure of the air inlet cap is usually a thin-walled horn-shaped structure with a large-diameter thin-walled opening, a small-diameter solid bottom and a thin-walled conical section.

[0003] Ti65 is a high-performance titanium alloy, and a sufficient and uniform deformation in the two-phase region is needed to obtain a microstructure with excellent comprehensive performance. However, when the traditional pie blank direct die forging process is used to form such an air inlet cap forging, the following problems may occur: (1) the conical thin-walled section has a long metal flow distance, a severe deformation and a fast surface temperature drop during the forming process, which leads to a decrease in the plasticity of the blank and a surface cracking of the forging; (2) the small-diameter solid bottom limits the metal flow, forming a small deformation zone, which is in sharp contrast with the large deformation zone of the conical thin-walled section, resulting in a large difference in the microstructure and performance of the forging; (3) due to the large projected area of the forging and the low deformation temperature of the conical thin-walled section, the metal deformation resistance is large, resulting in a large forming load (up to 14000 tons) during die forging; (4) the "horn-shaped" structure causes the problems of high punch and deep die in the die, and the punch is severely worn, and the die is stress concentrated, which finally leads to a short die life and a high cost. Figure 1 As shown in the figure, the strain distribution of the forging under the traditional pie blank + die forging process is uneven. SUMMARY

[0004] The purpose of the present application is to provide a Ti65 alloy air inlet cap forging uniform deformation control process, which solves the problems of surface cracking, uneven deformation, large forming load and severe die wear of the Ti65 alloy air inlet cap forging during die forging.

[0005] To achieve the above purpose, the present application adopts the following technical scheme: A Ti65 alloy air inlet cap forging uniform deformation control process, comprising the following steps: Step 1: preparation of the original rough blank; According to the volume of the final forging, a Ti65 alloy cylindrical bar is obtained, and the bar is processed to form an original rough blank with a fillet feature a and a bevel positioning feature b; The fillet feature a has a fillet radius of 30mm-50mm, and the fillet radius is not less than one-third of the diameter D of the bar; The bevel positioning feature b is a bevel with a length of 20mm-50mm; Step 2: pre-forging forming; The original blank obtained in step 1 is heated at a temperature of 990-1010 DEG C and kept for not less than 4 hours, and then pre-forging forming is carried out at a temperature range of 980±30 DEG C with a deformation of not less than 30%, to obtain a pre-forging blank; The shape of the pre-forging blank comprises: a trapezoidal protruding feature c at the bottom, the top width w of the protruding feature c is 1 / 6-2 / 9 of the diameter D of the bar, and the height is not greater than the height of the small end of the final forging; A tapered slope feature d with the same slope as the tapered section of the final forging; A groove feature e on the tapered slope feature d; Step 3: pre-forging forming; The pre-forging blank obtained in step 2 is heated at a temperature of 1000-1030 DEG C and kept for not less than 2 hours, and then final forging forming is carried out at a temperature range of 1000±20 DEG C, to obtain the air inlet cap cover forging; The final forging forming mold is provided with a protruding feature f matched with the groove feature e and the trapezoidal protruding feature c, and the sum of the heights of the groove feature e and the trapezoidal protruding feature c is equal to the height of the protruding feature f.

[0006] Further, the Ti65 alloy cylindrical bar for the final forging is: pi x D x H / 4=V, wherein V is the volume of the final forging, and D and H are the diameter and length of the bar respectively. 2 ×H / 4=V, wherein V is the volume of the final forging; D, H are the diameter and length of the bar respectively.

[0007] Further, the height and width of the groove feature (e) and the trapezoidal protruding feature (c) are equal.

[0008] Compared with the prior art, the present application has the following beneficial effects: (1) By ingenious design of the shape of the pre-forging blank, the deformation of each part of the forging is redistributed, so that the deformation of the difficult deformation area (small diameter solid bottom) is improved, and the deformation of the large deformation area (tapered thin wall section) is controlled, and finally the overall uniform deformation is realized, ensuring the consistency of the microstructure and performance.

[0009] (2) The severe deformation and temperature drop of the tapered thin wall section in the first forming are reduced, and the plasticity of the region is improved, which fundamentally inhibits the generation of surface cracking.

[0010] (3) Through the deformation distribution of pre-forging and final forging, the final forging forming load is reduced from about 14000 tons in the traditional method to about 7000 tons, with a reduction of 50%.

[0011] (4) The reduction of forming load and the optimization of deformation distribution effectively reduce the stress and wear of the die, especially improve the problems of punch wear and die stress concentration, thereby significantly improve the service life of the die and reduce the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The strain distribution diagram of the forged piece of the biscuit + die forging process.

[0013] Figure 2 The schematic diagram of the original rough blank shape used in the present application.

[0014] Figure 3 The schematic diagram of the pre-forging blank shape prepared in the present application.

[0015] Figure 4 The schematic diagram of the positioning condition of the final forging process of the present application.

[0016] Figure 5 The schematic diagram of the deformation distribution of the forged piece after the final forging of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0018] The Ti65 alloy intake cap forging uniform deformation control process described in the present embodiment optimizes through numerical simulation, designs a special pre-forging blank shape, transfers part of the deformation of the conical thin wall section to the solid bottom of small diameter, and finally realizes the coordinated and uniform deformation of the whole forging. The specific steps are as follows: Step 1: Preparation of original rough blank; adopt Ti65 alloy cylindrical bar stock, calculate and determine the diameter D and length H of the bar stock according to the volume V of the final forging. Process the bar stock to form an original rough blank with two key features, as shown in Figure 2 The feature a: R30~50mm fillet; this feature can avoid too large temperature difference at the sharp corner and the blank body, which is beneficial to the control of microstructure uniformity. The fillet radius should be not less than one third of the diameter D of the bar stock. Feature b: 20~50mm long bevel; this feature is used to realize accurate positioning of the blank during pre-forging, and ensure the process stability between batches.

[0019] Step 2: Pre-forging; heat the above original rough blank at 990~1010℃ for not less than 4 hours, then deform not less than 30% in the temperature range of 980±30℃ by using the pre-forging die, and obtain Figure 3The pre-forging blank is shown. The pre-forging blank comprises three key shape features: feature c: a bottom trapezoidal protrusion. The protrusion top width w is between 1 / 6 and 2 / 9 of the diameter D of the bar stock, and the height thereof should not be greater than the height of the small end of the forged piece. The portion plays a role of guiding metal flow and increasing bottom deformation during finish forging. Feature d: a tapered slope. The slope is the same as that of the tapered section of the final forged piece. The feature pre-allocates the deformation of the tapered section to a reasonable level in the pre-forging stage, avoids excessive deformation in one time during finish forging, thereby realizing coordinated deformation of each part and significantly reducing forming load and die stress. Feature e: a groove structure. The feature is in correspondence with feature c.

[0020] Step 3: finish forging, heating the pre-forging blank at 1000-1030 °C for not less than 2 hours, and then finish forging by using a finish forging die at a temperature range of 1000±20 °C to obtain a final forged piece with uniform deformation as shown in Figure 5 The finish forging die is provided with feature f as shown in Figure 4 、 5 The feature f, together with features e and c of the pre-forging blank, further controls and improves the deformation of the bottom of the forged piece.

[0021] Taking a Ti65 alloy air inlet cap cover forged piece of an aero-engine as an example, the volume V of the final forged piece is obtained by three-dimensional modeling calculation; according to the value of V, a Ti65 alloy bar stock with a diameter D of φ350 mm is selected, and the blanking length H thereof is determined by calculation. Subsequently, the original rough blank with a fillet radius R=40 mm (feature a) and a bevel length of 30 mm (feature b) is machined by a lathe.

[0022] The original rough blank is heated at 1000 °C for 4.5 hours, and then pre-forging is performed at 970 °C. The pre-forging die cavity is designed according to the numerical simulation results, and the pre-forging blank obtained has a feature c with a top width w of 65 mm and a height of 90% of the height of the small end of the forged piece; feature d has a slope of 45°; feature e is the same height and width as feature c.

[0023] The pre-forging blank is heated at 1015 °C for 2.5 hours, and then finish forging is performed at 1010 °C. The finish forging process is smooth and has no cracking phenomenon. It is detected that the deformation of each part of the forged piece is uniform, the microstructure and performance meet the requirements of the technical standard, and the finish forging tonnage is about 7200 tons, and the die wear condition is greatly improved compared with the traditional process.

[0024] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change within the technical range disclosed by the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A Ti65 alloy inlet cap swage forging uniform deformation control process characterized by, The method comprises the following steps: Step 1: original blank preparation; According to the volume of the final forging, a Ti65 alloy cylindrical bar is obtained, and the bar is processed to form an original blank with a fillet feature a and a bevel positioning feature b; The fillet radius of the fillet feature a is 30mm~50mm, and the fillet radius is not less than one-third of the diameter D of the bar; The bevel positioning feature b is a bevel with a length of 20mm~50mm; Step 2: pre-forging forming; The original blank obtained in step 1 is heated at a temperature of 990℃~1010℃ and kept for not less than 4 hours, and then pre-forging forming is carried out at a temperature range of 980±30℃, with a deformation of not less than 30%, to obtain a pre-forging blank; The shape of the pre-forging blank includes: a trapezoidal protruding feature c at the bottom, the top width w of the protruding feature c is 1 / 6~2 / 9 of the diameter D of the bar, and the height is not greater than the height of the small end of the final forging; A conical bevel feature d with the same slope as the conical section of the final forging; A groove feature e on the conical bevel feature d; Step 3: pre-forging forming; The pre-forging blank obtained in step 2 is heated at a temperature of 1000℃~1030℃ and kept for not less than 2 hours, and then final forging forming is carried out at a temperature range of 1000±20℃ to obtain the inlet cap cover forging; A protruding feature f is provided in the final forging die to cooperate with the groove feature e and the trapezoidal protruding feature c, and the sum of the height of the groove feature e and the trapezoidal protruding feature c is equal to the height of the small end of the final forging.

2. A Ti65 alloy inlet cowl forging uniform deformation control process according to claim 1, characterized in that, Based on the volume of the final forging, the Ti65 alloy cylindrical bar stock is obtained as: π×D 2 ×H / 4=V, where V is the volume of the final forging; D and H are the diameter and length of the bar stock, respectively.

3. A Ti65 alloy inlet cowl forging uniform deformation control process according to claim 1, characterized in that, The height and width of the groove feature (e) and the trapezoidal protruding feature (c) are equal.

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