CN114054585A - Hot press forming method of thin-wall variable-curvature titanium alloy shell - Google Patents
Hot press forming method of thin-wall variable-curvature titanium alloy shell Download PDFInfo
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- CN114054585A CN114054585A CN202111340664.9A CN202111340664A CN114054585A CN 114054585 A CN114054585 A CN 114054585A CN 202111340664 A CN202111340664 A CN 202111340664A CN 114054585 A CN114054585 A CN 114054585A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D31/00—Other methods for working sheet metal, metal tubes, metal profiles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/10—Die sets; Pillar guides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/16—Heating or cooling
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Abstract
A hot press forming method of a thin-wall variable-curvature titanium alloy shell belongs to the technical field of titanium alloy forming. The invention solves the problems that when the existing thin-wall variable-curvature shell part is manufactured, the working procedure is complex and the operation difficulty is higher when the superplastic forming process is adopted, and the requirement on the thickness of the plate is higher when the hot-press forming process is adopted. Adopting a forming die comprising an upper die, a lower die and a blank holder, wherein the design of the die molded surface is based on the curvature characteristics of the part, and the straight line section, the circular arc section and the spherical section of the die molded surface are completely attached to the straight line section, the circular arc section and the spherical section of the part; and (3) heating the die, after heating is finished, contacting the plate with the upper die through the blank holder, keeping the position of the plate until the plate is fully preheated, and finally closing the die and maintaining the pressure. According to the design, a thick plate with the thickness of more than 5mm is not needed, the thin plate with the thickness of only 3mm can be formed, the wall thickness reduction amount of each part is not more than 0.5mm, the linear dimensional tolerance of the actual molded surface is not more than 0.3mm, and sufficient machining allowance is guaranteed for the final machining of the subsequent parts.
Description
Technical Field
The invention relates to a hot press forming method of a thin-wall variable-curvature titanium alloy shell, and belongs to the technical field of titanium alloy forming.
Background
The thin-wall variable-curvature shell is a core component of an aerospace attitude and orbit control engine storage box. When the part works, the air cavity of the storage tank is pressurized through the external connecting pipe, so that the shell is deformed and overturned, the volume of the liquid cavity of the storage tank is controlled to be reduced, the propellant is stably discharged, and the functions of propelling, posture adjusting and the like of the aircraft are realized. The molded surface of the part of the thin-wall variable-curvature shell structure is formed by connecting a straight line section, an arc section and a spherical section, wherein the straight line section and the horizontal plane form a certain angle.
Titanium alloy is the most suitable material for the thin-wall variable-curvature shell due to the advantages of light weight, high strength, corrosion resistance and the like. However, titanium alloy has low plasticity, large rebound resilience and high deformation resistance at normal temperature, so that the titanium alloy plate is subjected to deformation processing by hot press forming or superplastic forming in the prior art. The superplastic forming process in the superplastic forming process is complex and has high cost, the guarantee difficulty of the air pressure loading uniformity of each part is high during forming, and the local blowing-through condition is often generated. Therefore, in the hot processing technology of the titanium alloy plate, the hot press forming is relatively more economical, the cost is lower, and the complexity of the technological process is lower than that of the superplastic forming. In the aspect of process control, the control difficulty of the hot-press forming process is lower than that of superplastic forming, the forming success rate is higher than that of superplastic forming, and the condition that parts are scrapped in the machining process rarely occurs. However, in the prior art, when the thin-wall variable-curvature shell is formed by hot pressing, the molded surface of the hot pressing mold is often manufactured into a spherical surface, and the manufactured part is a spherical shell and is manufactured by machining. The spherical shell has the same integral curvature radius, if a thin plate is adopted for forming, the subsequent machining allowance is often insufficient, so that a thick plate of 5-8mm is required for forming, but the thick plate is difficult to form, the thick plate can be formed by hot pressing for many times, and the damage to a mold is large.
Disclosure of Invention
The invention further provides a hot press forming method of the thin-wall variable-curvature titanium alloy shell, which aims to solve the technical problems.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a hot-press forming method of a thin-wall variable-curvature titanium alloy shell comprises the following steps:
the method comprises the following steps: preparing a mould: adopting a forming die comprising an upper die, a lower die and a blank holder, wherein the design of the die molded surface is based on the curvature characteristics of the part, and the straight line section, the circular arc section and the spherical section of the die molded surface are completely attached to the straight line section, the circular arc section and the spherical section of the part; closing an upper die and a lower die, placing the upper die and the lower die on a platform of a hot press forming machine, placing a blank holder between the lower die and the upper die, moving the upper die upwards to separate the upper die from the lower die, and then heating the die;
step two: preheating a plate material: after the temperature of the die is raised, the blank holder is lifted to a position between the lower die and the upper die and higher than the topmost end of the lower die, after the blank holder is in place, the plate is placed on the blank holder, then the blank holder is moved upwards until the plate is contacted with the upper die, and the position is kept until the plate is fully preheated;
step three: forming: and (4) carrying out die assembly and pressure maintaining after preheating is finished, carrying out die drawing after pressure maintaining is finished, accelerating die drawing after the upper die is completely separated from the part, taking out the part, and finishing hot press forming.
Further, in the first step, before the temperature of the die is increased, the distance between the upper die and the lower die is 30-50 cm.
Further, in the first step, the temperature of the mold is raised to 740-760 ℃.
Further, in the second step, the position is kept for 5-8min after the blank holder is moved upwards.
Furthermore, in the third step, the die closing pressure is 40t-50t, and the upper die pressing rate is 1-2 mm/s.
Further, in the third step, the pressure maintaining time is 12-15min after die assembly.
Further, in the third step, the mold drawing speed is 1mm/s after the pressure maintaining is finished.
Furthermore, the die material is selected from medium silicon molybdenum nodular cast iron, cast steel, carbon steel or stainless steel.
Furthermore, an upper die profile with a downward opening is arranged on the upper die, the upper die profile and the upper surface of the part are arranged in a conformal manner, the spherical diameter of the spherical section, the circular arc radius of the circular arc section, the length of the linear section and the angle of the linear section of the upper die profile are the same as those of the upper surface of the part, and the top end of the upper die is also provided with an exhaust hole; a lower die molded surface is processed on the lower die, the lower die molded surface is arranged along the shape of the lower surface of the part, and the spherical diameter of the spherical section, the circular arc radius of the circular arc section, the length of the straight line section and the angle of the straight line section of the lower die molded surface are the same as those of the lower surface of the part; the middle part of the blank holder is provided with a through hole, the blank holder is sleeved on the lower die through the through hole, and the lower die profile is higher than the upper surface of the blank holder; lifting lugs are fixedly arranged on the side faces of the upper die, the lower die and the blank holder.
Compared with the prior art, the invention has the following effects:
the molded surface of the hot-press forming die is designed according to the molded surface of the shell, the molded surfaces of the upper die and the lower die of the die are matched with the molded surface structure of the part and are formed by connecting three sections, namely a straight section, an arc section and a spherical section, the hot-press forming die designed in the way can be directly manufactured into a variable-curvature shell, a thick plate with the thickness of more than 5mm is not needed, a thin plate with the thickness of only 3mm can be formed, the wall thickness of the final formed part is 2.5-3mm, the thickness reduction of the wall thickness of each part is not more than 0.5mm, the linear dimensional tolerance of the actual molded surface is not more than 0.3mm, the angular dimensional tolerance is not more than 20', and sufficient machining allowance is ensured for the final machining of the subsequent parts.
Drawings
FIG. 1 is a schematic view of a thin-walled variable curvature titanium alloy housing part;
FIG. 2 is a schematic front view of the upper die;
FIG. 3 is a schematic front view of the lower mold;
FIG. 4 is a schematic front view of a blank holder;
FIG. 5 is a schematic front view of step two;
fig. 6 is a schematic front view of the step three-in-one molding state.
Detailed Description
The first embodiment is as follows: in the present embodiment, a hot press forming method for a thin-walled variable-curvature titanium alloy case is described with reference to fig. 1 to 6, and includes the following steps:
the method comprises the following steps: preparing a mould: adopting a forming die comprising an upper die 1, a lower die 2 and a blank holder 3, wherein the design of the die profile is based on the curvature characteristic of the part 4, and the straight line section, the circular arc section and the spherical section of the die profile are completely attached to the straight line section, the circular arc section and the spherical section of the part 4; the upper die 1 and the lower die 2 are closed and placed on a platform of a hot press forming machine, the blank holder 3 is placed between the lower die 2 and the upper die 1, the upper die 1 is moved upwards to separate the upper die 2 from the lower die, and then the temperature of the die is raised; the lower die molded surface is attached to the concave molded surface of the part 4, the upper die molded surface is attached to the convex molded surface of the part 4, and the straight line segment of the die is identical to the straight line segment of the part 4 in angle. After the die is closed, a gap exists between the upper die 1 and the lower die 2, and the value of the gap is equal to the thickness of the used plate 5 and the theoretical thickness of the shell part 4. The heated die comprises an upper die, a lower die and a blank holder.
Step two: preheating a plate material 5: after the temperature of the die is raised, the blank holder 3 is lifted to a position between the lower die 2 and the upper die 1 and higher than the topmost end of the lower die 2, after the blank holder is in place, the plate 5 is placed on the blank holder 3, then the blank holder 3 is moved upwards until the plate 5 is contacted with the upper die 1, and the position is kept until the plate 5 is fully preheated;
step three: forming: and (3) carrying out die assembly and pressure maintaining after preheating is finished, carrying out die drawing after pressure maintaining is finished, accelerating die drawing after the upper die 1 and the part 4 are completely separated, taking out the part 4, and finishing hot press forming.
Although the hot-press forming method is also adopted in the application, the molded surface of the hot-press forming die is designed according to the molded surface of the shell, the molded surfaces of the upper die and the lower die of the die are matched with the structure of the molded surface of the part 4 and are formed by connecting a straight line segment, an arc segment and a spherical segment, the hot-press forming die designed in the way can be directly manufactured into the variable-curvature shell, a thick plate with the thickness of more than 5mm is not needed, the thin plate with the thickness of only 3mm can be formed, the final formed wall thickness is 2.5-3mm, the wall thickness reduction quantity of each part 4 is not more than 0.5mm, the linear dimensional tolerance of the actual molded surface is not more than 0.3mm, and the angular dimensional tolerance is not more than 20', so that sufficient machining allowance is ensured for the final machining of the subsequent part 4.
The method is suitable for forming various grades of titanium alloy plates with the thickness of 2.0-3.0 mm.
In the first step, before the temperature of the die is raised, the distance between the upper die 1 and the lower die 2 is 30-50 cm. In particular to the distance between the lowest point of the upper die and the highest point of the lower die.
In the first step, the temperature of the mold is raised to 740-.
In the second step, the position of the blank holder 3 is kept for 5-8min after moving upwards.
In the third step, the mold closing pressure is 40t-50t, and the pressing rate of the upper mold 1 is 1-2 mm/s.
And in the third step, the pressure maintaining time is 12-15min after the die is closed.
In the third step, the stripping speed is 1mm/s after the pressure maintaining is finished.
The die material is medium silicon molybdenum nodular cast iron, cast steel, carbon steel or stainless steel.
An upper die profile with a downward opening is arranged on the upper die 1, the upper die profile and the upper surface of the part 4 are arranged in a shape following manner, the spherical diameter of the spherical section, the circular arc radius of the circular arc section, the length of the linear section and the angle of the linear section of the upper die profile are the same as those of the upper surface of the part 4, and the top end of the upper die 1 is also provided with an exhaust hole; a lower die molded surface is processed on the lower die 2, the lower die molded surface is arranged along the shape of the lower surface of the part 4, and the spherical diameter of the spherical section, the circular arc radius of the circular arc section, the length of the straight line section and the angle of the straight line section of the lower die molded surface are the same as those of the lower surface of the part 4; a through hole is formed in the middle of the blank holder 3, the blank holder 3 is sleeved on the lower die 2 through the through hole, and the profile of the lower die 2 is higher than the upper surface of the blank holder 3; lifting lugs 6 are fixedly arranged on the side faces of the upper die 1, the lower die 2 and the blank holder 3. The spherical diameter of the spherical section of the thin-wall variable-curvature titanium alloy shell is SR, the circular arc radius of the circular arc section is R, the length of the straight line section is L, the angle of the straight line section is A, and the thickness of the plate is delta. The sphere diameter of the spherical section of the upper die molded surface is SR + delta, the arc radius of the circular arc section is R + delta, the length of the straight line section is L + delta, the angle of the straight line section is A + delta, the sphere diameter of the spherical section of the lower die molded surface is SR, the arc radius of the circular arc section is R, the length of the straight line section is L, and the angle of the straight line section is A.
The design size of the thin-wall variable-curvature titanium alloy shell is preferably 156mm in spherical section spherical diameter SR, 200mm in arc section arc radius R, 86 degrees in straight section angle A and 3mm in plate thickness delta.
Claims (9)
1. A hot press forming method of a thin-wall variable-curvature titanium alloy shell is characterized by comprising the following steps: it comprises the following steps:
the method comprises the following steps: preparing a mould: the method comprises the following steps that a forming die comprising an upper die (1), a lower die (2) and a blank holder (3) is adopted, wherein the design of a die molded surface is based on the curvature characteristics of a part (4), and a straight line section, an arc section and a spherical section of the die molded surface are completely attached to the straight line section, the arc section and the spherical section of the part (4); the upper die (1) and the lower die (2) are closed and placed on a platform of a hot press forming machine, a blank holder (3) is placed between the lower die (2) and the upper die (1), the upper die (1) is moved upwards to separate the upper die from the lower die (2), and then the temperature of the die is raised;
step two: preheating a plate (5): after the temperature of the die is raised, the blank holder (3) is lifted to a position between the lower die (2) and the upper die (1) and higher than the topmost end of the lower die (2), after the blank holder is in place, the plate (5) is placed on the blank holder (3), then the blank holder (3) is moved upwards until the plate (5) is in contact with the upper die (1), and the position is maintained until the plate (5) is fully preheated;
step three: forming: and (3) carrying out die assembly and pressure maintaining after preheating is finished, carrying out die drawing after pressure maintaining is finished, accelerating die drawing after the upper die (1) is completely separated from the part (4), taking out the part (4), and finishing hot press forming.
2. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 1, wherein: in the first step, before the temperature of the die is raised, the distance between the upper die (1) and the lower die (2) is 30-50 cm.
3. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 2, wherein: in the first step, the temperature of the mold is raised to 740-.
4. The method for hot press forming of a thin-walled variable curvature titanium alloy shell according to claim 1, 2 or 3, wherein: in the second step, the position of the blank holder (3) is kept for 5-8min after moving upwards.
5. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 1, wherein: in the third step, the die closing pressure is 40t-50t, and the pressing rate of the upper die (1) is 1-2 mm/s.
6. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 5, wherein: and in the third step, the pressure maintaining time is 12-15min after the die is closed.
7. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 6, wherein: in the third step, the stripping speed is 1mm/s after the pressure maintaining is finished.
8. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 1, wherein: the die material is medium silicon molybdenum nodular cast iron, cast steel, carbon steel or stainless steel.
9. The method for hot press forming of the thin-walled variable-curvature titanium alloy shell according to claim 1, wherein: an upper die molded surface (11) with a downward opening is formed in the upper die (1), the upper die molded surface (11) and the upper surface of the part (4) are arranged in a shape following mode, the spherical diameter of a spherical section, the circular arc radius of a circular arc section, the length of a straight line section and the angle of the straight line section of the upper die molded surface (11) are the same as those of the upper surface of the part (4), and an exhaust hole (12) is formed in the top end of the upper die (1); a lower die molded surface (21) is processed on the lower die (2), the lower die molded surface (21) is arranged along the shape of the lower surface of the part (4), and the spherical diameter of the spherical section, the circular arc radius of the circular arc section, the length of the straight line section and the angle of the straight line section of the lower die molded surface (21) are the same as those of the lower surface of the part (4); a through hole (31) is formed in the middle of the blank holder (3), the blank holder (3) is sleeved on the lower die (2) through the through hole (31), and the profile of the lower die (2) is higher than the upper surface of the blank holder (3); lifting lugs (6) are fixedly arranged on the side surfaces of the upper die (1), the lower die (2) and the blank holder (3).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111340664.9A CN114054585A (en) | 2021-11-12 | 2021-11-12 | Hot press forming method of thin-wall variable-curvature titanium alloy shell |
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| CN202111340664.9A CN114054585A (en) | 2021-11-12 | 2021-11-12 | Hot press forming method of thin-wall variable-curvature titanium alloy shell |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114799001A (en) * | 2022-03-30 | 2022-07-29 | 西安航天发动机有限公司 | Hot processing method for forming large-size storage box hemisphere blank by adopting single-action hydraulic press |
| CN114850304A (en) * | 2022-04-28 | 2022-08-05 | 北京航空航天大学 | Combined forming method of aviation variable-section curvature component |
-
2021
- 2021-11-12 CN CN202111340664.9A patent/CN114054585A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114799001A (en) * | 2022-03-30 | 2022-07-29 | 西安航天发动机有限公司 | Hot processing method for forming large-size storage box hemisphere blank by adopting single-action hydraulic press |
| CN114850304A (en) * | 2022-04-28 | 2022-08-05 | 北京航空航天大学 | Combined forming method of aviation variable-section curvature component |
| CN114850304B (en) * | 2022-04-28 | 2022-12-16 | 北京航空航天大学 | Combined forming method of aviation variable cross-section curvature component |
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