A forming process method for a complex multi-boss box-shaped titanium alloy sheet metal part

Abstract

The application discloses a forming process method of a complex multi-convex-box-shaped titanium alloy sheet metal part, and the titanium alloy blank is preliminarily hot-pressed to preliminarily form the forming surface of the titanium alloy part and facilitate positioning of the position and shape of the convex on the titanium alloy part. Then, a flexible pad layer is laid on the forming surface of the titanium alloy part, and the forming surface of the titanium alloy part is compensated by the flexible pad layer in the hot-pressing gap, so that the problem that the forming surface of the titanium alloy part is prone to generating wave lines or wrinkles in the conventional hot-pressing mode due to machining precision error of a die, die use loss and thin titanium alloy sheet metal is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of compressor assembly, and relates to a forming process method of a complex multi-boss box-shaped titanium alloy sheet metal part. BACKGROUND

[0002] With the urgent demand of the aerospace industry for high-mach number, high-maneuverability and high-carrying performance aircraft, the demand for lightweight of aircraft structures is increasingly strong on the premise of ensuring strength and rigidity. The high strength and corrosion resistance of titanium alloy make it increasingly used on aircraft in a large area.

[0003] Titanium alloy has poor plasticity at room temperature, and is usually formed by heating. The commonly used forming process method is hot pressing forming. For thin plate multi-boss complex titanium alloy parts, due to the complex structure and thin plate, the closing gap of the forming tool cannot be completely consistent. Therefore, it is easy to cause the titanium alloy blank to be in contact in some areas after closing, and under the action of the top touch of the first contact area, the local area of the titanium alloy blank is empty and cannot be completely attached, finally leading to the non-standard of the film adhesion degree of the formed part.

[0004] In addition, in the hot pressing forming, the hot pressing and hot deep drawing forming dies are deformed due to long-term bearing of high temperature and high pressure in batch production, thereby causing the surface pressure of the part to be unevenly stressed in the forming process, the local material is difficult to reach the yield strength to produce plastic deformation, and the sheet metal is easy to flow to the direction of the large gap of the die during forming, so that the area with poor film adhesion degree of the part appears corrugation.

[0005] The above situations all affect the forming quality of the multi-boss complex structure box-shaped titanium alloy part, therefore, the application discloses a forming process method of a complex multi-boss box-shaped titanium alloy sheet metal part. SUMMARY

[0006] The application aims to provide a forming process method of a complex multi-boss box-shaped titanium alloy sheet metal part, which adopts preliminary hot pressing forming in the process of hot pressing forming of the titanium alloy blank, then adds a flexible pad layer as a medium on the forming surface of the preliminarily formed titanium alloy part and performs secondary high-temperature shaping, so as to solve the problems of non-film adhesion of the forming surface of the titanium alloy part with bosses and wave wrinkles on the surface of the forming surface in the hot pressing forming process.

[0007] The application is achieved by the following technical scheme:

[0008] A complex multi-boss box-shaped titanium alloy sheet metal part forming process method adopts a hot pressing die to preliminarily hot press form a blank to determine the boss position, then prepares a flexible pad layer of a corresponding shape according to the shape projection shape of the formed part and the boss position, lays the flexible pad layer on the forming surface of the part, and re-presses and shapes the formed part, and separates the flexible pad layer from the formed part after the re-pressing and shaping.

[0009] To better realize the present application, further, the following steps are specifically included:

[0010] Step 1, a hot pressing die is used to preliminarily hot press form a titanium alloy blank under a first temperature condition with a first clamping force, and the pressure is maintained for a first time;

[0011] Step 2, the hot pressing die is opened, the projection of the pressed surface of the formed part is obtained to obtain the shape projection shape, and the boss position is positioned on the shape projection shape;

[0012] Step 3, the flexible pad layer of the corresponding shape is prepared according to the shape projection shape, and the flexible pad layer is laid on the forming surface of the formed part;

[0013] Step 4, a hot pressing die is used to re-press and shape the formed part under a second temperature condition with a second clamping force, and the pressure is maintained for a second time;

[0014] Step 5, the hot pressing die is opened, after the formed part is cooled to room temperature, the flexible pad layer is peeled off from the forming surface of the formed part, and the forming quality of the forming surface is checked, if the forming quality of the forming surface meets the standard, the part preparation is completed, if the forming quality of the forming surface does not meet the standard, the flexible pad layer is re-laid on the area of the forming surface with substandard quality and step 4 is repeated until the forming quality of the forming surface meets the standard.

[0015] By preliminarily hot pressing the titanium alloy blank, the forming surface of the titanium alloy part can be preliminarily formed, and the position and shape of the boss on the titanium alloy part can be positioned. Then the flexible pad layer is laid on the forming surface of the titanium alloy part, and the flexible pad layer compensates for the hot pressing gap of the forming surface of the titanium alloy part, which can solve the problem that the forming surface of the titanium alloy part is prone to wave or wrinkle under the conventional hot pressing mode due to the machining precision error of the die, the use and loss of the die, and the thin titanium alloy sheet.

[0016] On the other hand, by laying a flexible pad layer with appropriate thickness on the forming surface, the problem that the die is difficult to guarantee the quality of the profile surface due to the deformation of the die profile surface during long-term hot forming can be solved, and the forming surface of the titanium alloy part can be fully calibrated through the heat pressure gap compensation of the flexible pad layer; in addition, the forming and heat pressing mode combining preliminary hot pressing and re-pressing calibration can effectively reduce the forming damage of the die under long-time high-temperature and high-pressure environment, greatly prolong the service life of the die, thereby reducing the repair rate and scrap rate of the die tooling, saving the cost and guaranteeing the forming quality of the titanium alloy part.

[0017] In order to better realize the present application, further, the thickness of the flexible pad layer is 0.2mm-0.3mm, and the distance between the edge of the flexible pad layer and the bending edge of the formed part is 2mm-3mm.

[0018] In order to better realize the present application, further, the flexible pad layer is laid on the forming surface of the formed part in step 4, and the formed part and the flexible pad layer are preheated for 5min-10min.

[0019] In order to better realize the present application, further, the flexible pad layer is laid in the order of laying away from the boss area first and laying close to the boss area.

[0020] In order to better realize the present application, further, the flexible pad layer is graphite paper.

[0021] In order to better realize the present application, further, the first temperature is 660℃-700℃, the first die clamping force is 20kg / cm 2 -25kg / cm 2 , and the first time is 5min-10min.

[0022] In order to better realize the present application, further, the second temperature is 720℃-750℃, the second die clamping force is 35kg / cm 2 -50kg / cm 2 , and the second time is 15min-20min.

[0023] In order to better realize the present application, further, the gap is 0.2mm-0.5mm.

[0024] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0025] The present application carries out preliminary hot press forming on the titanium alloy blank under the first temperature condition with the first die closing force, so that the titanium alloy blank is preliminarily formed into a titanium alloy part and the boss position and the boss shape are determined, then a flexible pad layer with a corresponding shape is prepared according to the projection shape of the forming surface of the titanium alloy part, and an avoiding opening is arranged on the flexible pad layer corresponding to the position of the boss, the flexible pad layer is uniformly laid on the forming surface of the titanium alloy part, then the forming surface of the titanium alloy part covered with the flexible pad layer is re-pressed and shaped under the second temperature condition with the second die closing force, the gap between the forming surface of the titanium alloy part and the pressing die surface of the hot press die is compensated through the flexible pad layer, so as to ensure that the forming surface of the titanium alloy part can be fully shaped; at the same time, the forming hot press mode combining preliminary hot press forming and re-pressing and shaping can effectively reduce the forming damage of the die under the long-time high-temperature and high-pressure environment, greatly prolong the service life of the die, thereby reducing the repair rate and scrap rate of the die tooling, saving the cost and ensuring the forming quality of the titanium alloy part. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic view of a hot press die;

[0027] Figure 2 is a schematic view of a titanium alloy part;

[0028] Figure 3 is a schematic view of a flexible pad layer after cutting;

[0029] Figure 4 is a schematic view of the laying of a flexible pad layer. DETAILED DESCRIPTION

[0030] The following detailed description is exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0031] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, unless otherwise explicitly stated by the present application, the singular form is intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0032] For the convenience of description, if "upper", "lower", "left" and "right" appear in the present application, they only mean the same as the upper, lower, left and right directions of the drawing itself, and do not limit the structure, but only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application, which indicates or implies that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0033] The terms "mounting", "connecting", "connecting", "fixing" and the like in the present application should be understood broadly, for example, it can be fixed connection, or detachable connection, or one body; it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, it can be internal connection of two elements, or interaction relationship of two elements, for ordinary skilled in the art, the above-mentioned terms can be understood according to the specific meaning of the present application.

[0034] Embodiment 1:

[0035] The forming process method of the complex multi-boss box-shaped titanium alloy sheet metal part of the embodiment adopts a hot pressing die to preliminarily hot press form the blank to determine the boss position, then prepares a flexible pad layer with a corresponding shape according to the shape projection shape of the formed part and the boss position, lays the flexible pad layer on the forming surface of the part, and re-presses and shapes the formed part, and separates the flexible pad layer from the formed part after the re-pressing and shaping.

[0036] Specifically includes the following steps:

[0037] Step 1, using a hot pressing die to preliminarily hot press form the titanium alloy blank under the first temperature condition with the first closing force, and pressurizing for the first time;

[0038] Step 2, open the hot pressing die, project the pressure surface of the formed part to obtain the shape projection shape, and position the boss position on the shape projection shape;

[0039] Step 3, according to the shape projection shape, cut and prepare a flexible pad layer with a corresponding shape, and cut out an avoidance port on the flexible pad layer corresponding to the boss position and the boss shape, and lay the cut flexible pad layer on the forming surface of the formed part;

[0040] Step 4, using a hot pressing die to re-press and shape the formed part under the second temperature condition with the second closing force, and pressurizing for the second time;

[0041] Step 5, open the hot press mold, after the formed part cools to room temperature, peel off the flexible pad layer from the formed surface of the formed part and check the forming quality of the formed surface, if the forming quality of the formed surface meets the standard, the part preparation is completed, if the forming quality of the formed surface does not meet the standard, re-lay the flexible pad layer on the area of the formed surface where the quality does not meet the standard and repeat step 4 until the forming quality of the formed surface meets the standard.

[0042] As shown in Figure 1 , the hot press forming mold includes a concave mold and a convex mold, the TC4 titanium alloy sheet blank is placed between the concave mold and the convex mold, the concave mold and the convex mold press the TC4 titanium alloy sheet blank at a first temperature condition with a first mold closing force for the first time, so that the TC4 titanium alloy sheet blank is preliminarily hot pressed and formed, after a first pressure holding time, the concave mold and the convex mold are opened and the preliminarily formed titanium alloy part is taken out and cooled to room temperature, the preliminarily formed titanium alloy part is as shown in Figure 2 .

[0043] As shown in Figure 3 and Figure 4 , a flexible pad layer of a corresponding shape is prepared according to the projection shape of the formed surface of the titanium alloy part, and an avoidance opening is cut out on the flexible pad layer corresponding to the boss position and the boss shape, that is, to ensure that the non-boss area on the formed surface of the titanium alloy part is covered with the flexible pad layer, and the boss area on the formed surface of the titanium alloy part is not covered with the flexible pad layer. Further ensure that in the subsequent re-pressing and shaping process, the non-boss area on the formed surface of the titanium alloy part is in contact with the mold pressing surface in advance, ensuring that the non-boss area on the formed surface of the titanium alloy part is hot pressed and formed before the boss area. After the flexible pad layer is laid, the concave mold and the convex mold are pressed and shaped at a first temperature condition with a first mold closing force, and the titanium alloy part is finally formed after a second pressure holding time.

[0044] Through the above steps, the film adhesion of the formed surface of the titanium alloy part can be improved, and wrinkles or ripples on the formed surface can be avoided, thereby improving the forming quality of the formed surface of the titanium alloy part.

[0045] The other parts of this embodiment are the same as those of embodiment 1, and will not be described again.

[0046] Example 2

[0047] The forming process method of the complex multi-boss box-shaped titanium alloy sheet metal part of this embodiment is improved on the basis of embodiment 1, the thickness of the flexible pad layer is 0.2-0.3 mm, and the distance between the edge of the flexible pad layer and the bending edge of the formed part is 2-3 mm.

[0048] The thickness of the flexible pad layer is too thin to compensate for the hot pressing gap, and thus cannot guarantee that sufficient and uniform pressure is applied to the forming surface of the titanium alloy part during the re-pressing and shaping process. The thickness of the flexible pad layer is too thick to cause the shaping pressure to be too large, which in turn causes the forming surface of the titanium alloy part and the flexible pad layer itself to wrinkle. Therefore, in order to ensure that the compensation amount of the flexible pad layer is appropriate, the thickness of the flexible pad layer is preferably set to 0.2mm-0.3mm. The areas where wrinkles or corrugations are prone to occur on the forming surface of the titanium alloy part, such as the areas near the bending edges and the areas near the bosses, can appropriately increase the thickness of the flexible pad layer to 0.3mm-0.35mm.

[0049] Further, after the flexible pad layer is laid on the forming surface of the formed part in step 4, the formed part and the flexible pad layer are preheated for 5min-10min, so that the temperature of the formed part is between the first temperature and the second temperature.

[0050] Further, the flexible pad layer is laid in the order of laying the flexible pad layer away from the boss area first and then laying the flexible pad layer near the boss area, to ensure that the non-boss area is fully covered with the flexible pad layer.

[0051] The flexible pad layer is graphite paper.

[0052] The other parts of this embodiment are the same as those of Example 1, and thus will not be described again.

[0053] Example 3:

[0054] The forming process method of a complex multi-boss box-shaped titanium alloy sheet metal part of this embodiment is improved based on Example 1 or 2, wherein the first temperature is 660℃-700℃, the first clamping force is 20kg / cm 2 -25kg / cm 2 , and the first time is 5min-10min.

[0055] Preferably, the first temperature is controlled to be between 670℃ and 685℃, and the first clamping force is controlled to be between 22kg / cm 2 -25kg / cm 2 .

[0056] The second temperature is 720℃-750℃, the second clamping force is 35kg / cm 2 -50kg / cm 2 , and the second time is 15min-20min.

[0057] Preferably, the second temperature is controlled to be between 730℃ and 740℃, and the second clamping force is controlled to be between 35kg / cm 2 -45kg / cm 2 .

[0058] The other parts of this embodiment are the same as those of Embodiment 1 or 2, and thus are not described again.

[0059] Embodiment 4

[0060] The forming process method of the complex multi-tubercle box-shaped titanium alloy sheet metal part of this embodiment is improved on the basis of any one of Embodiments 1-3. The gap is reserved between the escape opening and the edge of the tubercle, and the gap is 0.2mm-0.5mm. By setting the gap, the flexible pad layer has sufficient extension beam in the area close to the tubercle when it is pressed, thereby avoiding the flexible pad layer from being pressed to generate wrinkles in the position close to the tubercle during the hot pressing process.

[0061] The other parts of this embodiment are the same as those of any one of Embodiments 1-3, and thus are not described again.

[0062] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A process for forming a complex multi-boss box-shaped titanium alloy sheet metal part, characterized in that: The blank is preliminarily hot-pressed using a hot-pressing die to determine the boss position. A flexible cushion layer of corresponding shape is then prepared based on the projected shape of the formed part and the boss position. The flexible cushion layer is laid on the forming surface of the part, and the formed part is re-pressed and reshaped. After the re-pressing and re-shaping is completed, the flexible cushion layer is separated from the formed part. The specific steps include: Step 1: Using a hot pressing mold to perform preliminary hot pressing on the titanium alloy blank at a first temperature and with a first clamping force, and maintaining the pressure for a first time; Step 2: Open the hot pressing mold, project the pressure surface of the formed part to obtain the surface projection shape, and locate the boss position on the surface projection shape; Step 3: Cut and prepare a flexible cushion layer of corresponding shape according to the projection shape of the surface, and cut out an avoidance opening on the flexible cushion layer corresponding to the position and shape of the boss, and lay the cut flexible cushion layer flat on the forming surface of the formed part; Step 4: Using a hot pressing mold to re-press and correct the formed part at a second temperature with a second clamping force, and holding the pressure for a second time; Step 5: Open the hot pressing mold. After the formed part cools to room temperature, peel off the flexible cushion layer from the forming surface of the formed part and check the forming quality of the forming surface. If the forming quality of the forming surface meets the standard, the part preparation is completed. If the forming quality of the forming surface does not meet the standard, re-lay the flexible cushion layer on the area on the forming surface that does not meet the quality standard and repeat step 4 until the forming quality of the forming surface meets the standard. The first temperature is lower than the second temperature, the first mold clamping force is lower than the second mold clamping force, and the first time is lower than the second time.

2. The method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to claim 1, characterized in that: The thickness of the flexible pad is 0.2mm-0.3mm, and the distance between the edge of the flexible pad and the bending edge of the formed part is 2mm-3mm.

3. The method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to claim 2, characterized in that: After laying the flexible cushion layer on the forming surface of the formed part in step 4, the formed part and the flexible cushion layer are preheated for 5 minutes to 10 minutes.

4. The method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to claim 3, characterized in that: Lay the flexible cushion layer in the order of laying the area away from the boss first and then the area close to the boss.

5. The method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to claim 4, characterized in that: The flexible cushion layer is graphite paper.

6. A method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to any one of claims 2 to 5, characterized in that: The first temperature is 660°C-700°C, and the first clamping force is 20kg / cm 2 -25kg / cm 2 , the first time is 5min-10min.

7. A method for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to any one of claims 2 to 5, characterized in that: The second temperature is 720°C-750°C, and the second clamping force is 35kg / cm 2 -50kg / cm 2 , the second time is 15min-20min.

8. A process for forming a complex multi-boss box-shaped titanium alloy sheet metal part according to any one of claims 2 to 5, characterized in that: A gap is reserved between the avoidance opening and the edge of the boss, and the gap is 0.2mm-0.5mm.

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