A forging method for titanium alloy oblique T-shaped forging

Abstract

The present invention belongs to the field of forging and die design, and specifically relates to a forging method of a titanium alloy inclined T-shaped forging. The method comprises: heating a titanium alloy bar to a deformation temperature, and forging a blank to obtain a T-shaped blank by free forging; heating the T-shaped blank to a deformation temperature, rotating it 90 degrees on a horizontal plane and placing it in a preforming die, and forging a preformed part by using the preforming die, wherein the preformed part comprises an inclined boss and a bottom plate, wherein the inclined boss protrudes downward from the middle section of the bottom plate, and the inclined boss occupies at least 3 / 4 of the space in the middle section; the parting surface of the preforming die is the maximum cross section of the standing preformed part, and the maximum cross section is a curved surface; heating the preformed part to a deformation temperature, and forging it with a preforging die to obtain a preforging; heating the preforging part to a deformation temperature, and forging it with a final forging die to obtain a die forging.

Description

Technical Field

[0001] The invention belongs to the field of forging and die design, and in particular relates to a forging method of a titanium alloy oblique T-shaped forging. Background Art

[0002] Titanium alloy inclined T-shaped forgings are complex die forgings used in aviation. Due to their complex structural characteristics, they are not easy to form in one die forging during die design, and have a great impact on the die and forging equipment. On the other hand, the rough blanks are complex and difficult to realize, and cracks are prone to occur due to large deformation, and the performance is not easy to meet the standards. Summary of the invention

[0003] The purpose of the present invention is to design a forging method for a titanium alloy oblique T-shaped forging, so as to ensure that the forging is well filled, the size meets the requirements of the drawings, the performance is qualified, and the blank is simple and easy to realize.

[0004] The invention solves the problem of difficult forging by designing preforming, preforging and final forging and controlling reasonable forging process parameters, while causing less damage to the die and forging equipment, making the blank simple and easy to implement, and having qualified physical and chemical properties.

[0005] To solve this technical problem, the technical solution of the present invention is:

[0006] A forging method for a titanium alloy oblique T-shaped forging, the method comprising:

[0007] The titanium alloy bar is heated to a deformation temperature and free forged to obtain a T-shaped blank;

[0008] The T-shaped blank is heated to a deformation temperature, rotated 90 degrees on a horizontal plane and placed on a preforming die, and forged using the preforming die to obtain a preformed part, the preformed part comprising an inclined boss and a bottom plate, the inclined boss protruding downward from the middle section of the bottom plate, and the inclined boss occupies at least 3 / 4 of the space in the middle section; the parting surface of the preforming die is the maximum cross section of the standing preformed part, and the maximum cross section is a curved surface;

[0009] The preform is heated to a deformation temperature and forged with a preforging die to obtain a preforged part;

[0010] The pre-forging is heated to the deformation temperature and forged with a final forging die to obtain a die forging.

[0011] Before heating the titanium alloy bar to a deformation temperature and free forging the blank to obtain a T-shaped blank, the method further comprises:

[0012] Design matching dies according to the outer dimensions of die forgings, including preforming dies, pre-forging dies, and final forging dies;

[0013] The T-shaped blank is designed according to the outer dimensions of the preformed forging.

[0014] For preforming dies, matching dies are designed according to the outer dimensions of the die forgings, including:

[0015] According to the maximum cross section of the standing preform, the characteristic points of the preform on the parting surfaces of the upper and lower molds are determined;

[0016] The starting point and the end point of the characteristic points are connected in sequence to form a curve. The surface formed by this curve is the curved parting surface of the mold, which can evenly divide the preformed part into upper and lower parts. The preform mold is determined according to the parting surface and the outer dimensions of the preformed forging.

[0017] Among them, the preform can be designed according to the outer dimensions of the preforging, with equal cross-section and equal volume conversion, and it is ensured that the deformation of the preform is uniform when forging to the preforging, and the deformation is about 20% to 50%.

[0018] Design matching dies according to the outer dimensions of die forgings, including:

[0019] First, design the final forging die that matches the shape of the hot forging according to its dimensions;

[0020] Secondly, the design of the pre-forging die is based on the outer dimensions of the pre-forging and the design of the final forging die that matches its shape; among them, the pre-forging is designed based on the outer dimensions of the forging, with equal cross-section and equal volume conversion, to ensure that the deformation of the pre-forging is uniform when forging to the final forging, and the deformation is about 20% to 35%.

[0021] The size of the final forging die is designed using a design formula, which states that the size of the final forging die is equal to ((forging size × (1 + material thermal shrinkage)).

[0022] Design T-shaped blank according to the dimensions of preformed forgings, including:

[0023] According to the outer dimensions of the preform close to the oblique T-shape, 5mm underpressure and 30mm wide and 8mm deep burrs are added to the equal cross-section, and the oblique T-shaped blank is obtained by equal volume conversion;

[0024] The method is to convert the oblique T-shaped blank into a T-shaped blank with equal cross-section and volume.

[0025] The preforming process includes:

[0026] Put the T-shaped blank into the electric furnace for heating. The heating specification is 35℃ below the phase change point. The holding time is calculated according to the holding coefficient of 0.6~0.8min / mm.

[0027] Put the heated and insulated T-shaped blank into the preforming mold;

[0028] The preforming die is hammered with three hammers of 2800t energy to fill the cavity of the T-shaped blank. The hammering interval is 15s. The first hammer strikes lightly to position the die. The second and third hammers are forged until the die is closed and the forging is under-stressed by ≤5mm. The final forging temperature is not less than 820℃ to obtain a preformed part.

[0029] The pre-forging process includes:

[0030] The preform is placed in an electric furnace for heating. The heating specification is: 35°C below the phase change point, and the holding time is calculated based on the insulation coefficient of 0.6 to 0.8 min / mm;

[0031] placing the heated and heat-insulated preform into a pre-forging die;

[0032] The pre-forging die is hammered 3 times with an interval of 15s. The first hammer has an impact energy of 2800t, the second hammer has an impact energy of 4000t, and the third hammer has an impact energy of 5600t. The die is forged until the underpressure of the forging is ≤5mm and the final forging temperature is not less than 820℃ to obtain a pre-forged die.

[0033] The final forging process includes:

[0034] The pre-forged parts are heated in an electric furnace. The heating specifications are as follows: preheating to 35°C below the phase change point, and the holding time is calculated based on the holding coefficient of 0.6-0.8min / mm. After preheating, heat to 15°C above the phase change point, and the holding time is calculated based on the holding coefficient of 0.25-0.5min / mm.

[0035] Put the heated and insulated pre-forging into the final forging die;

[0036] The final forging die is hammered 3 times with an interval of 15s. The first hammer has a 20mm thick pad with an impact energy of 2800t; the second hammer has a 10mm thick pad with an impact energy of 4000t, and the third hammer has no pad with an impact energy of 5600t until the die is closed, the forging is under-pressured ≤5mm, and the final forging temperature is not lower than 820℃ to obtain the die forging.

[0037] The beneficial effects of the present invention are as follows: by designing T-shaped blank, free forging blank, preforming, preforging and final forging, reasonable forging parameters are controlled so that each process meets the requirements and forgings with good filling and qualified performance are successfully obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions implemented in the present invention, the following is a brief explanation of the drawings required to be used in the embodiments of the present invention. Obviously, the drawings described below are only embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0039] Figure 1A schematic diagram of a forging provided by the present invention.

[0040] Figure 2 It is a schematic diagram of a T-shaped blank of the present invention.

[0041] Figure 3 This is a diagram of a preform of the present invention.

[0042] Figure 4 This is a diagram of a pre-forging according to the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0044] The various aspects and features of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to fully understand the present invention. However, it is obvious to those skilled in the art that the present invention can also be implemented without these specific details. The following description of the embodiments is only for a better understanding of the present invention by illustrating examples of the present invention. The present invention is not limited to any specific settings and methods provided below, but covers all product structures, any improvements, replacements, etc. of methods covered without departing from the spirit of the present invention.

[0045] The present invention provides a forming method of a titanium alloy oblique T-shaped die forging, including free forging T-shaped blank, preforming, preforging, die forging and other steps, and strictly controlling the heating temperature, holding time, striking energy and pressing distance respectively, so as to obtain a forging with qualified filling performance. Figure 1 shown.

[0046] Free forging T-shaped blank (such as Figure 2 As shown in the figure), preforming, pre-forging, the heating temperatures of the three links are all the same. The forging is heated to 35℃ below the phase change point, and the insulation coefficient is calculated as 0.6~0.8mm / s; the die forging adopts a step heating method, preheating is heated to 35℃ below the phase change point, and the insulation coefficient is calculated as 0.6~0.8mm / s. After the preheating, the temperature is raised to 15℃ above the phase change point, and the insulation coefficient is calculated as 0.25~0.5mm / s.

[0047] The forming method of titanium alloy oblique T-shaped die forgings has the following specific steps:

[0048] Step 1: First, the design of the final forging die is based on the dimensions of the hot forging ((forging dimensions × (1 + material thermal shrinkage)) to design a die that matches its shape; second, the design of the pre-forging die is based on the dimensions of the pre-forging to design a die that matches its shape, and the pre-forging is designed based on the dimensions of the forging, equal cross-section and equal volume conversion to ensure that the deformation of the pre-forging is uniform when forging to the final forging, and the deformation is about 20% to 35%; third, the design of the pre-forming die is based on the dimensions of the pre-forming forging to design a die that matches its shape , analyze the structural features of the preform, determine the characteristic points of the preform on the upper and lower mold parting surfaces (the curved surface formed by the characteristic points divides the upper and lower volumes of the preform equally), connect the starting points and end points of the characteristic points in sequence to form a curve, and the curved surface formed by this curve is the curved parting surface of the mold. The preform mold is determined based on the parting surface and the outer dimensions of the preform forging. The preform is designed based on the outer dimensions of the preform, with equal cross-section and equal volume conversion, and it is ensured that the deformation of the preform is uniform when forging to the preform, and the deformation is about 20% to 50%;

[0049] Step 2: Design T-shaped blank. The shape of the preform is close to the oblique T shape. Therefore, according to the shape size of the preform, 5mm underpressure and 30mm wide and 8mm deep burrs are added on the basis of equal cross-section, and the equal volume is converted to obtain an oblique T-shaped blank. However, the production of oblique T-shaped blanks is difficult. Therefore, the oblique T-shaped blank with equal cross-section and equal volume is converted into a T-shaped blank. When the T-shaped blank is preformed, it is rotated 90° on the horizontal plane and placed on the mold for preforming. It is ensured that the T-shaped blank is slowly transitioned from the forging to the preform, and the deformation is uniform. The main deformation is 20% to 50%, and 10% to 15% in some parts.

[0050] Step 3: Free forging T-shaped blank, put the titanium alloy bar into the electric furnace for heating, heating specification: 35℃ below the phase change point, holding time is calculated according to the holding coefficient of 0.6~0.8min / mm, free forging blank includes two steps of material division, drawing and shaping, deformation is controlled within 20%~50%, and the final forging temperature is not less than 820℃;

[0051] Step 4: Heat the blank to the deformation temperature, and preform the T-shaped blank to obtain a preformed part (such as Figure 3 as shown).

[0052] The T-shaped blank is heated in an electric furnace. The heating specification is: 35℃ below the phase change point, the holding time is calculated according to the holding coefficient of 0.6~0.8min / mm, and the cavity is filled with three hammers with 2800t energy. The first hammer strikes lightly to position, and the second and third hammers are struck 10s apart. The mold is closed, and the forging is under-pressurized ≤5mm. The final forging temperature is not less than 820℃ to obtain a preform.

[0053] Step 5: The preform is heated to the deformation temperature, and the preform is pre-forged to obtain a pre-forged part (such as Figure 4 The preform is heated in an electric furnace. The heating specification is: 35°C below the phase change point, the holding time is calculated according to the holding coefficient of 0.6-0.8min / mm, the number of forging hammer blows is 3 times, the hammer blow interval is 15s, the first hammer has a striking energy of 2800t, the second hammer has a striking energy of 4000t, and the third hammer has a striking energy of 5600t. The forging is forged until the die is closed, the forging is under-pressured ≤5mm, and the final forging temperature is not less than 820°C to obtain a pre-forged part.

[0054] Step 6: Heat the pre-forging to the deformation temperature, and use the final forging die to forge to obtain the die forging. The pre-forging is heated in an electric furnace. The heating specification is: preheating to 35°C below the phase change point, and the holding time is calculated according to the insulation coefficient of 0.6-0.8min / mm. After preheating, heat to 15°C above the phase change point, and the holding time is calculated according to the insulation coefficient of 0.25-0.5min / mm. The number of forging hammers is 3 times, and the hammer interval is 15s. The first hammer is padded with a 20mm thick pad and 2800t impact energy; the second hammer is padded with a 10mm thick pad and 4000t impact energy. The third hammer is not padded with a pad and 5600t impact energy is forged until the die is closed, the forging is under-pressure ≤5mm, and the final forging temperature is not lower than 820°C to obtain the die forging.

[0055] Embodiment 1

[0056] Step 1: First, the design of the final forging die is based on the hot forging (see Figure 1 ) The outer dimensions ((forging outer dimensions × (1 + material thermal shrinkage)) are designed to match the shape of the die; secondly: the design of the pre-forging die is based on the pre-forging (see Figure 4 ) The design of the die matches its shape according to the outer dimensions of the forging, and the pre-forging is designed according to the outer dimensions of the forging, with equal cross-section and equal volume conversion, to ensure that the deformation of the pre-forging is uniform when forging to the final forging, and the deformation is about 20% to 35%; again: the design of the pre-forming die is based on the pre-forming forging (see Figure 4 ) Design a mold that matches its shape according to its dimensions, analyze the structural features of the preform, determine the characteristic points of the preform on the parting surface of the upper and lower molds (the curved surface formed by the characteristic points divides the upper and lower volumes of the preform equally), connect the starting and end points of the characteristic points in sequence to form a curve, and the curved surface formed by this curve is the curved parting surface of the mold. Determine the preforming mold based on the parting surface and the dimensions of the preformed forging. The preform is designed based on the dimensions of the preform, with equal cross-section and equal volume conversion, and ensures that the deformation of the preform is uniform when forging to the preform, and the deformation is about 20% to 50%;

[0057] Step 2: Design T-shaped blank (see Figure 2 ), the shape of the preform is close to an oblique T shape, so according to the preform ( Figure 3) is added with 5mm underpressure and 30mm wide and 8mm deep burrs on the basis of equal cross-section, and the equal volume conversion is obtained to obtain an oblique T-shaped blank. However, the production of oblique T-shaped blanks is difficult. Therefore, the oblique T-shaped blanks with equal cross-section and equal volume are converted into T-shaped blanks. When the T-shaped blanks are preformed, they are rotated 90° on the horizontal plane and placed on the mold for preforming. It is ensured that the T-shaped blanks are slowly transitioned from forging to preformed parts, and the deformation is uniform. The main deformation is 20% to 50%, and 10% to 15% in some parts.

[0058] Step 3: Determine the blanking specification of Φ250×300mm according to the size of the titanium alloy oblique T-shaped blank. Heat the bar to 934℃ (phase transition point of this batch of materials is 969℃) for insulation, insulation time is 180min, insulation coefficient is 0.7min / mm, and forge the T-shaped blank out of the furnace, including two steps of material division, lengthening and shaping. The deformation is controlled within 20% to 50%, and the final forging temperature is measured to be 832℃;

[0059] Step 4: Heat the T-shaped blank to 934℃ (phase transition point of this batch of materials is 969℃) for insulation, insulation time is 130min, insulation coefficient is 0.7min / mm, take out of the furnace and preform the T-shaped blank, fill the cavity with three hammers of 2800t energy, the first hammer strikes lightly to position, and the second and third hammers are struck at intervals of 10s, the mold is closed, the vertical dimension of the forging is 192 and the actual measurement is 191; the final forging temperature is measured at 866℃, and the preform is obtained;

[0060] Step 5: Heat the preform to 934°C (phase transition point of this batch of materials is 969°C) for insulation, insulation time is 100min, insulation coefficient is 0.7min / mm, pre-forge the preform after it is taken out of the furnace, forging hammer times are 3 times, hammer interval time is 15s, the first hammer has a striking energy of 2800t, the second hammer has a striking energy of 4000t, and the third hammer has a striking energy of 5600t. Forge until the die is closed, the vertical dimension of the forging is 90 and the actual measurement is 90; the final forging temperature is measured at 872°C, and the preforging is obtained;

[0061] Step 6: Preheat the pre-forging to 934°C and keep it warm for 90 minutes, with a thermal insulation coefficient of 0.7min / mm. After preheating, heat it to 984°C and keep it warm for 50 minutes, with a thermal insulation coefficient of 0.3min / mm. The number of forging hammer strikes is 3 times, with a hammer strike interval of 15s. The first hammer strikes a 20mm thick pad with a striking energy of 2800t; the second hammer strikes a 10mm thick pad with a striking energy of 4000t, and the third hammer strikes without a pad with a striking energy of 5600t until the die is closed. The vertical dimension of the forging is 55 and the actual measurement is 57; the final forging temperature is measured at 872°C to obtain the die forging.

[0062] The forgings were inspected and accepted according to the technical requirements. The forgings were full of good dimensions and qualified, and the performance was qualified after physical and chemical testing.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A forging method for a titanium alloy oblique T-shaped forging, characterized in that: The method comprises the following steps: The titanium alloy bar is heated to a deformation temperature and free forged to obtain a T-shaped blank; The T-shaped blank is heated to a deformation temperature, rotated 90 degrees on a horizontal plane and placed on a preforming die, and forged using the preforming die to obtain a preformed part, the preformed part comprising an inclined boss and a bottom plate, the inclined boss protruding downward from the middle section of the bottom plate, and the inclined boss occupies at least 3 / 4 of the space in the middle section; the parting surface of the preforming die is the maximum cross section of the standing preformed part, and the maximum cross section is a curved surface; The preform is heated to a deformation temperature and forged with a preforging die to obtain a preforged part; The pre-forging is heated to a deformation temperature and forged with a final forging die to obtain a die forging; The titanium alloy bar is heated to the deformation temperature, and before the free forging process is performed to obtain a T-shaped blank, the process also includes: Design matching dies according to the outer dimensions of die forgings, including preforming dies, pre-forging dies, and final forging dies; Design T-shaped blank according to the dimensions of the preform; For preforming dies, matching dies are designed according to the outer dimensions of the die forgings, including: According to the maximum cross section of the standing preform, the characteristic points of the preform on the parting surfaces of the upper and lower molds are determined; Connect the starting point and the end point of the characteristic points in sequence to form a curve. The surface formed by this curve is the curved parting surface of the mold, which can evenly divide the preformed part into upper and lower parts. The preform mold is determined according to the parting surface and the outer dimensions of the preformed part. The preform is designed according to the external dimensions of the preforging, with equal cross-section and equal volume conversion, and the deformation of the preform is ensured to be uniform when forging to the preforging, and the deformation is about 20% to 50%; According to the external dimensions of the die forgings, matching pre-forging dies and final forging dies are designed, including: First, design the final forging die that matches the shape of the die forging according to its external dimensions; Secondly, the design of the pre-forging die is to design a pre-forging die that matches its shape based on the outer dimensions of the pre-forging; among them, the pre-forging is designed based on the outer dimensions of the die forging, with equal cross-section and equal volume conversion, to ensure that the deformation of the pre-forging is uniform when forging into the die forging, and the deformation is about 20% to 35%.

2. The method according to claim 1, characterized in that The size of the final forging die is designed using a design formula, which states that the size of the final forging die is equal to the forging outer dimensions × (1 + material thermal shrinkage).

3. The method according to claim 2, characterized in that Design T-shaped blank according to the dimensions of the preform, including: According to the outer dimensions of the preform close to the oblique T-shape, 5mm underpressure and 30mm wide and 8mm deep burrs are added to the equal cross-section, and the oblique T-shaped blank is obtained by equal volume conversion; Convert the oblique T-shaped blank with equal cross section and volume into a T-shaped blank.

4. The method according to claim 3, characterized in that The preforming process includes: Put the T-shaped blank into the electric furnace for heating. The heating specification is 35℃ below the phase change point. The holding time is calculated according to the holding coefficient of 0.6~0.8min / mm. Put the heated and insulated T-shaped blank into the preforming mold; The preforming die is hammered with three hammers of 2800t energy to fill the cavity of the T-shaped blank. The hammering interval is 15s. The first hammer strikes lightly to position the die. The second and third hammers are forged until the die is closed and the forging is under-stressed by ≤5mm. The final forging temperature is not less than 820℃ to obtain a preformed part.

5. The method according to claim 4, characterized in that The pre-forging process includes: The preform is placed in an electric furnace for heating. The heating specification is: 35°C below the phase change point, and the holding time is calculated based on the insulation coefficient of 0.6 to 0.8 min / mm; placing the heated and heat-insulated preform into a pre-forging die; The pre-forging die is hammered 3 times with an interval of 15s. The first hammer has an impact energy of 2800t, the second hammer has an impact energy of 4000t, and the third hammer has an impact energy of 5600t. The die is forged until the underpressure of the forging is ≤5mm and the final forging temperature is not less than 820℃ to obtain a pre-forged die.

6. The method according to claim 5, characterized in that The final forging process includes: The pre-forged parts are heated in an electric furnace. The heating specifications are as follows: preheating to 35°C below the phase change point, and the holding time is calculated based on the holding coefficient of 0.6-0.8min / mm. After the preheating, heat to 15°C above the phase change point, and the holding time is calculated based on the holding coefficient of 0.25-0.5min / mm. Put the heated and insulated pre-forging into the final forging die; The final forging die is hammered 3 times with an interval of 15s. The first hammer has a 20mm thick pad with an impact energy of 2800t; the second hammer has a 10mm thick pad with an impact energy of 4000t, and the third hammer has no pad with an impact energy of 5600t until the die is closed, the forging is under-pressured ≤5mm, and the final forging temperature is not lower than 820℃ to obtain the die forging.

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