A blank-making method for open-die forging of a titanium alloy complex die forging with a large drop and thin plate

Abstract

The present invention belongs to the field of titanium alloy forging, and particularly relates to a blank-making method for open-die forging of large-drop thin-plate type titanium alloy complex die forgings. The method includes: blanking; heating the bar stock in a resistance furnace; forging the bar stock on an open-die forging hammer, first upsetting along the streamline direction, then upsetting perpendicular to the streamline direction after sizing and shaping, and then elongating and shaping along the streamline direction after sizing; heating the blank and placing it in a resistance furnace; forging the blank on an open-die forging hammer, using a cylindrical tooling to press on the square blank to forge the required large-radius fillet; then using a flat pressing plate with a length less than the width of the final size of the blank to press and form along the direction of the required thin plate, so that the pressed thin plate is tangent to the large-radius fillet; repeating the above steps for multiple times of cylindrical tooling pressing and flat pressing plate pressing until the required size of the final thin plate is reached; sizing.

Description

Technical Field

[0001] The present invention belongs to the field of titanium alloy forging, and particularly relates to a blank-making method for open-die forging of large-drop thin-plate titanium alloy complex die forgings. Background Art

[0002] Titanium alloys have characteristics such as high specific strength, high temperature resistance, and good corrosion resistance, and are widely used in fields such as aviation, aerospace, high-speed rail, weapons, and ships. Titanium alloys belong to difficult-to-deform alloys, and the main forming method is forging. The design of the rough shape of forgings has an important impact on the forming of the final die forgings. For forgings with a large drop (drop ratio > 4) and a thin plate thickness dimension ≤ 40 mm and complex structures, the traditional manufacturing process is multi-pass pre-forging - machining between passes - final forging. However, its disadvantages such as complex forging process, low material utilization rate, and high forging cost further limit its application. Summary of the Invention

[0003] The purpose of the present invention is to propose a forging method with simple blank-making and forming in view of the above-mentioned deficiencies of the existing technology. By using a forming tooling and adopting open-die forging technology to complete the forging of the blank, it can effectively improve the production efficiency for the subsequent forging of die forgings, and is simple and feasible, providing a reference for blank-making of this type of die forgings.

[0004] Technical Solution:

[0005] A blank-making method for open-die forging of large-drop thin-plate titanium alloy complex die forgings includes:

[0006] Step 1: Cutting the material;

[0007] Step 2: Placing the bar stock in a resistance furnace for heating, with the heating temperature being Tβ - 20°C to Tβ - 60°C and the heat preservation coefficient being 0.8 to 1.2 min / mm; placing the bar stock on an open-die forging hammer for forging. First, upset along the flow line direction, then perform sizing and shaping, and then upset along the direction perpendicular to the flow line direction. After sizing, perform stretching and shaping along the flow line direction to make the height of the blank reach 85% - 95% of the height of the forging, the length reach 65% - 75% of the forging, and the width reach 85% - 95% of the forging; Tβ is the phase transformation temperature;

[0008] Step 3: Heating the blank, placing it in a resistance furnace, with the heating temperature being Tβ - 20°C to Tβ - 60°C and the heat preservation coefficient being 0.8 to 1.2 min / mm; placing the blank on an open-die forging hammer for forging. Use a cylindrical tooling to press on the square blank to forge the required large-radius fillet; then use a flat pressing plate with a length less than the width of the final size of the blank to press and form along the direction of the required thin plate, so that the pressed thin plate is tangent to the large-radius fillet;

[0009] Repeat Step 3 for multiple times of cylindrical tooling pressing and flat pressing plate pressing until the required size of the final thin plate is reached;

[0010] Step Four: Shaping.

[0011] The first pressing amount a1 of the cylindrical tooling and the flat pressing plate is:

[0012] The subsequent pressing amount a each time i is:

[0013] The initial offset b of the axis of the cylindrical tooling from the boundary line between the thick and thin plates of the forging is:

[0014] The width T of the flat pressing plate tooling is:

[0015] Wherein, L is the total length of the blank; L1 is the length of the thick plate; H is the thickness of the blank; H1 is the thickness of the thin plate; i is the number of pressing times; R is the radius of the cylindrical tooling; s is the number of feeding times of the flat pressing plate tooling.

[0016] The process of Step Two allows multiple heat treatments to be completed, and the deformation amount per heat treatment is controlled within 30% - 35%.

[0017] After Step Three, the final length of the blank reaches 90% - 95% of the forging, the drop reaches 55% - 65% of the forging, and the drop ratio > 2.5.

[0018] The process of Step Three allows multiple heat treatments to be completed, and the deformation amount per heat treatment is controlled within 20% - 30%.

[0019] Shaping includes:

[0020] Placing it in a resistance furnace for heating, the heating temperature is Tβ - 20°C to Tβ - 60°C, and the heat preservation coefficient is 0.8 - 1.0 min / mm;

[0021] Placing the blank on a free forging hammer, and locally upsetting and shaping the forging to obtain a final blank that meets the requirements.

[0022] Blanking includes:

[0023] According to the dimensional requirements of the forging, select an appropriate bar stock specification for blanking, and chamfer the two ends.

[0024] Beneficial effects: The present invention realizes the production of blanks for large-drop thin-plate titanium alloy die forgings through the above method. This method has the advantages of simple process, low cost, short forging time, etc., and realizes the qualified production of large-drop thin-plate titanium alloy die forgings. Description of the Drawings

[0025] Figure 1 It is a process route diagram.

[0026] Figure 2Schematic diagram of the anvil pressing down for each hammer blow. Detailed implementation method

[0027] Example 1:

[0028] The forging material: TA18 titanium alloy, phase transformation point 950 °C, the outer contour dimensions of the forging are 445×340×202 mm, both sides of the forging in the width direction are chamfered, the height dimension of the thin plate is 40 mm, and the drop ratio is 5.05. Its process route is as Figure 1 shown, including:

[0029] Step 1: Blanking. According to the forging size requirements, select a bar stock specification of φ200×375 mm for blanking, and chamfer the two ends with a fillet radius of R10.

[0030] Step 2: Heat the bar stock described in Step 1 above, place it in a resistance furnace, with a heating temperature of 930 °C and a holding time of 160 min. Forge the bar stock on a 3T free forging hammer. First, upset it along the streamline direction until reduce and shape it to 210×267, and then upset it along the direction perpendicular to the streamline to 240×204. After reducing, stretch and shape it in the third direction to make the blank size reach 270×300×150 mm, and complete the forging within 3 heat treatments.

[0031] Step 3: Heat the blank described in Step 2 above, place it in a resistance furnace, with a heating temperature of 930 °C and a holding time of 150 min. Forge the blank on a 3T free forging hammer. Place the arc-shaped column tooling above the length of the square blank to ensure that the high part of the final rough shape does not deform, as Figure 2 shown. Forge the required fillet with R≥80 mm; then use a flat pressing plate to press to achieve axial stretching of the blank, repeat the operation of Step 3, and the length of the blank is 380, and this process is completed in 2 heat treatments.

[0032] where i = 5, H = 150; H1 = 60, s = 10; L = 420; L1 = 160;

[0033] As Figure 2 shown, according to the formula, it can be known that:

[0034] Step 4: Heat the blank described in Step 3 above, place it in a resistance furnace, with a heating temperature of 930 °C and a holding time of 120 min. Forge the blank on a 3T free forging hammer. Upset and shape the two front corners of the thin plate of the blank locally. Finally, the length of the blank is 420 mm, the thickness of the thin plate is 60 mm, and the drop ratio is 2.5, obtaining a qualified blank.

[0035] Example 2:

[0036] Forging material: TC4 titanium alloy, phase transformation point 1005°C, forging outer dimension 648×501×300mm, both sides of the forging in the width direction are missing corners, the height dimension of the thin plate is 40mm, and the drop ratio is 6.

[0037] Step 1: Blanking. According to the forging size requirements, select the bar stock specification for blanking, and chamfer the two ends with a fillet of R10.

[0038] Step 2: Heat the bar stock described in Step 1 above, place it in a resistance furnace, heat it to 950°C, and keep it warm for 280 minutes. Place the bar stock on a 16MN hydraulic press for forging. First, upset it along the streamline direction to reduce and shape it to □380×477mm, then upset it along the direction perpendicular to the streamline to □410×410mm, and after reducing, draw out and shape it in the third direction to make the blank size reach 490 (length) × 470 (width) × 300mm (height), which is completed in 3 heating passes.

[0039] Step 3: Heat the blank described in Step 2 above, place it in a resistance furnace, heat it to 955°C, and keep it warm for 300 minutes. Place the blank on a 2500t hydraulic press for forging. Use the arc-shaped column tooling above the length of the square blank to ensure that the high part of the final rough shape does not deform, as shown in the attached drawing. Forge the required fillet with R≥120mm; then use a flat pressing plate to press to achieve axial drawing of the blank, and turn the blank 90°, and press along the direction perpendicular to the axis. Repeat the operation. Finally, the length of the blank is 580mm, and this process is completed in 2 heating passes.

[0040] where i = 10, H = 300; H1 = 60; s = 13; L = 620; L1 = 240; R = 120mm;

[0041] As Figure 2 shown, according to the formula, it can be known that:

[0042] Step 4: Heat the blank described in Step 3 above, place it in a resistance furnace, heat it to 960°C, and keep it warm for 240 minutes. Place the blank on a 2500t hydraulic press for forging. Upset and shape the two front corners of the thin plate of the blank locally. Finally, the length of the blank is 620mm, the thickness of the thin plate is 60mm, and the drop ratio is 5, obtaining a qualified blank that meets the requirements.

Claims

1. A blank-making method for open-die forging of a large-drop thin-plate titanium alloy complex die forging, characterized in that, Including: Step 1: Blanking; Step 2: Place the bar stock in a resistance furnace for heating, with the heating temperature being Tβ - 20°C to Tβ - 60°C and the holding coefficient being 0.8 to 1.2 min / mm; place the bar stock on a free forging hammer for forging. First, upset along the flow line direction, after sizing and shaping, then upset along the direction perpendicular to the flow line, and after sizing, draw out and shape along the flow line direction to make the height of the blank reach 85% - 95% of the height of the forging, the length reach 65% - 75% of the forging, and the width reach 85% - 95% of the forging; Tβ is the phase transformation temperature. Step 3: Heat the blank, place it in a resistance furnace, with the heating temperature being Tβ - 20°C to Tβ - 60°C and the holding coefficient being 0.8 to 1.2 min / mm; place the blank on a free forging hammer for forging, use a cylindrical tooling to press on the square blank to forge the required large radius fillet; then use a flat pressing plate with a length less than the width of the final size of the blank to press and form along the direction of the required thin plate, so that the pressed thin plate is tangent to the large radius fillet. Repeat Step 3 for multiple times of cylindrical tooling pressing and flat pressing plate pressing until the required size of the final thin plate is reached. Step 4: Shaping; The first pressing-down amount a1 using the cylindrical tooling and the flat pressing plate is: ; The subsequent pressing amount a each time i is as follows: ; The initial offset b of the axis of the cylindrical tooling from the boundary line between the thick and thin plates of the forging is: ; The width T of the flat pressing plate tooling is: ; Wherein, L is the total length of the blank; L1 is the length of the thick plate; H is the thickness of the blank; H1 is the thickness of the thin plate; i is the number of down presses; R is the radius of the cylindrical tooling; s is the feed number of the flat pressing plate tooling.

2. The method according to claim 1, wherein The process in Step 2 is completed in multiple heats, and the deformation amount per heat is controlled within 30% - 35%.

3. The method according to claim 1, characterized in that After Step 3, the final length of the blank reaches 90% - 95% of the forging, the drop reaches 55% - 65% of the forging, and the drop ratio > 2.

5.

4. The method according to claim 3, characterized in that Step 3 is completed in multiple heats, and the deformation amount per heat is controlled within 20% - 30%.

5. The method according to claim 1, characterized in that, Shaping includes: Place it in a resistance furnace for heating, with the heating temperature being Tβ - 20°C to Tβ - 60°C and the holding coefficient being 0.8 to 1.0 min / mm; Place the blank on a free forging hammer, and locally upset and shape the forging to obtain the final blank that meets the requirements.

6. The method according to claim 1, wherein Blanking includes: According to the size requirements of the forging, select an appropriate bar stock specification for blanking, and chamfer the two ends.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1 - 6.

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