Device and method for controlling section shape and wall thickness of large-size thin-wall pipe fitting hot air pressure forming pipe fitting

Abstract

The invention belongs to the technical field of metal thin-wall pipe fitting annular section shape and wall thickness control, and provides a large-size thin-wall pipe fitting hot air pressure forming pipe fitting section shape and wall thickness control device and method. The device comprises a pipe blank annular section control device and a final forming die for controlling annular flowing of materials to achieve local stamping. The pipe blank annular section control device controls the section shape, and the final forming die is used for controlling the wall thickness and achieving local rapid cooling in the hot air pressure forming process. Through the synergistic effect of the inner pressing ball and the outer pressing ball, the cross section of the pipe blank generates local convex and local concave characteristics at the same time, and the stability of the pipe blank in the machining process is improved only by changing clamping grooves of the upper pressing ring and the lower pressing ring for the pipe blank with the specific shape and diameter. And a cooling water channel of the final forming die is specially designed, so that the specific position of the pipe blank is locally and rapidly cooled during hot air pressure forming, and the phenomenon of local thinning and cracking of the pipe blank is effectively prevented.

Description

Technical Field

[0001] The invention relates to the technical field of circumferential cross-sectional shape and wall thickness control of metal thin-walled pipe fittings, and in particular to a device and method for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe fitting formed by hot air pressing. Background Art

[0002] The hot gas forming process for pipes is an efficient metal processing technology that is widely used in the forming of thin-walled metal pipes with complex and irregular cross-sections. In the aerospace, automotive and other manufacturing fields, the hot gas forming process for pipes can produce lightweight, high-strength parts with complex cross-sectional features. For example, in the aviation field, the use of large-sized, complex and irregular cross-sectional thin-walled pipes in the wings, fuselage and tail of aircraft can reduce weight while ensuring their structural strength and rigidity. With the rapid development of the automotive industry, the chassis, body structural parts and other components of automobiles need to be further lightweight and strengthened to improve the power performance and safety of the automobile. Therefore, the hot gas forming process for pipes has outstanding advantages in the forming of large-sized, complex and irregular cross-sectional thin-walled parts in the aerospace and automotive industries.

[0003] Before hot press forming of large-sized, thin-walled, complex and irregular-section pipe fittings, the tube blanks placed in the hot press forming molds are often processed through multiple pre-processing steps such as bending, flattening, and preforming. At the beginning of hot press forming, the outer contour of the cross section at different axial positions of the tube blank is smaller than the cross section contour at the corresponding position in the mold cavity, and the degree of difference between the cross section shape of the tube blank at each position and the cross section shape at the corresponding position in the mold cavity is different. The hot press forming process of pipe fittings is essentially a process in which the cross section of the tube blank approaches the cross section of the corresponding mold cavity. This process directly determines the quality of the mold adhesion and wall thickness distribution of various parts of the pipe fittings after hot press forming. Therefore, it is necessary to reasonably preform the original tube blank to achieve a good matching relationship between the cross section shape of the preform and the corresponding mold cavity cross section.

[0004] In addition, in the hot state, because the yield strength of the material is low, its ability to transfer loads is also weakened, so it is difficult to achieve large load transfer in adjacent areas of the tube blank, tensile thinning, and compressive wrinkling. When the diameter of the tube blank is large, the deformation of the tube blank in the circumferential direction does not affect each other. Although the tube blank is a closed structure, it is no longer able to transfer circumferential stress, and the deformation of the tube blank becomes a plate deformation to a certain extent. That is, when there is a lot of material stored in a certain area on the tube blank, it is easy to form wrinkles that cannot be flattened after fitting the inner wall of the mold, and when there is less material stored in a certain area on the tube blank, it is easy to crack due to excessive thinning of the material. Since the tube blank cannot achieve material transfer through the mutual load transfer of materials in adjacent areas in the hot state, it is easy to cause serious local wrinkles and local thinning defects due to unreasonable material distribution at various locations on the initial tube blank.

[0005] In order to solve the problems of high difficulty in matching the shape of the preform with the mold cavity, difficulty in transferring materials from adjacent areas of the tube blank to each other in the hot state, and easy occurrence of serious local wrinkles and local thinning defects during rapid hot air forming of thin-walled tubes in the length and diameter directions of large-sized tubes, a method for controlling the cross-sectional shape and wall thickness of hot air forming tubes of thin walls of large-sized tubes is needed. Summary of the invention

[0006] The purpose of the present invention is to provide a device and method for controlling the cross-sectional shape and wall thickness of large-sized thin-walled pipes formed by hot air pressing, so as to achieve a good match between the shape of the preform and the corresponding mold cavity cross-section and solve the problems of local wrinkles and local thinning defects caused by the difficulty of transferring materials in adjacent areas of the pipe in a hot state.

[0007] The technical solution of the present invention is as follows: a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressing formed pipe, comprising a device for controlling the circumferential cross-sectional shape of a pipe blank and a final forming die for controlling the circumferential flow of materials to realize local stamping;

[0008] The tube blank annular cross-section control device controls the cross-section shape, and includes a lifting assembly, a transverse movement assembly, an inner extrusion assembly, an outer extrusion assembly, and a limit locking assembly; the target tube is fixed by the limit locking assembly, and the inner extrusion assembly and the outer extrusion assembly are moved to the position to be stamped by the lifting assembly and the transverse movement assembly for stamping;

[0009] The final forming die is used to control the wall thickness, and its shape follows the target stamping shape. A cooling water channel 30 is arranged on the final forming die to achieve local rapid cooling during the hot air pressure forming process.

[0010] The lifting assembly includes a vertical operating disc 1, a lifting screw 2, a main support plate 3, a round block 4, a positioning rod 5 and a blocking ring 6; one end of the lifting screw 2 is connected to the vertical operating disc 1, and the other end contacts the round block 4 after passing through the main support plate 3; the round block 4 is fixed on the mechanism support base plate 28; a positioning rod 5 passes through each of the two ends of the main support plate 3; one end of the positioning rod 5 is fixed on the mechanism support base plate 28, and a blocking ring 6 is installed on the other end of the positioning rod 5; the vertical operating disc 1 is manipulated to rotate the lifting screw 2, thereby driving the main support plate 3 to rise and fall.

[0011] The transverse movement assembly includes a horizontal operating disc 7, a transverse movement screw 8, a horizontal moving support frame 9, and a protective ring 10; one end of the transverse movement screw 8 is connected to the horizontal operating disc 7, and the other end is connected to the protective ring 10 after passing through the horizontal moving support frame 9; the horizontal moving support frame 9 is an inverted L-shape, and an external extrusion assembly is installed on its top surface; the horizontal operating disc 7 is operated to drive the transverse movement screw 8 to rotate, thereby driving the horizontal moving support frame 9 to move horizontally, and the protective ring 10 is used to limit and ensure the stability of the rotation of the transverse movement screw 8.

[0012] The external extrusion assembly includes a vertical hydraulic cylinder 19 and an external pressure ball 20; the vertical hydraulic cylinder 19 drives the external pressure ball 20 to perform lifting motion.

[0013] The internal extrusion assembly includes a horizontal hydraulic cylinder 11, a trapezoidal block 12, an internal pressure ball support plate 13, an internal extrusion fixed frame 14, a slide groove 15, a slide rod 16, a slider 17 and an internal pressure ball 18; the internal extrusion fixed frame 14 is provided with slide grooves 15 on both sides of one end, and the horizontal hydraulic cylinder 11 is installed in the other end; one end of the horizontal hydraulic cylinder 11 is connected to one side of the trapezoidal block 12, and the other side of the trapezoidal block 12 contacts the internal pressure ball support plate 13; the two ends of the internal pressure ball support plate 13 are connected to the slider 17, the slide rod 16 is fixed in the slide groove 15, and the slider 17 moves on the slide rod 16; 18 is fixed on the internal pressure ball support plate 13; the horizontal hydraulic cylinder 11 pushes the trapezoidal block 12 to move horizontally, and the internal pressure ball support plate 13 performs lifting movement under the push of the trapezoidal block 12, thereby driving the internal pressure ball 18 to perform lifting movement.

[0014] The limit locking assembly includes a partial connecting frame 21, a transverse connecting plate 22, an upper clamping ring 23, a lower support ring 24, a stabilizing ring 25, and a stabilizing rod 26; the partial connecting frame 21 is fixed on the main support plate 3 of the lifting assembly; the partial connecting frame 21 is fixedly connected to one end of the transverse connecting plate 22, and the other end of the transverse connecting plate 22 is fixedly connected to the upper clamping ring 23; the lower support ring 24 is fixed to the mechanism support bottom plate 28; the partial connecting frame 21 drives the transverse connecting plate 22 to move up and down, thereby driving the upper clamping ring 23 to move up and down; the upper clamping ring 23 and the lower support ring 24 work together to achieve limit locking of the tube blank; the stabilizing ring 25 is fixed on the upper clamping ring 23, and the stabilizing rod 26 is fixed on the mechanism support bottom plate; the stabilizing ring 25 and the stabilizing rod 26 control the stability of the upper clamping ring 23 moving up and down to prevent deviation.

[0015] The tube blank annular cross-section control device further includes a temperature control component; the temperature control component is an induction coil 27.

[0016] A method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressed formed pipe is implemented by a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressed formed pipe, and specifically comprises the following steps:

[0017] Step 1: Perform cross-sectional analysis on the target pipe to determine the position and shape of the local deformation of the pipe blank; through cross-sectional analysis of the pipe, design the shape and size of the inner pressure ball 18 and the outer pressure ball 20, and determine the size and feed amount of the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19;

[0018] Step 2: Design the upper clamping ring 23 and the lower support ring 24; design the clamping grooves of the upper clamping ring 23 and the lower support ring 24 according to the cross-sectional shapes of the two ends of the tube blank to ensure that the upper clamping ring 23 and the lower support ring 24 effectively lock the tube blank when closed;

[0019] Step 3: Design of the water channel of the final forming mold; according to the thermodynamic simulation calculation, cooling water channels 30 are arranged at the two side edges of the local raised fillet area of ​​the final forming mold cavity, so that the tube blank can be locally cooled during the final forming process;

[0020] Step 4: Assembling the tube blank; placing the tube blank on the lower support ring 24, operating the vertical operating disc 1 to lock the upper clamping ring 23 on the tube blank; operating the horizontal operating disc 7 to move the horizontal hydraulic cylinder to the part of the tube that needs local deformation;

[0021] Step 5: local stamping of the tube blank; after the tube blank is heated to the set temperature, the induction coil 27 is powered off; the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are started to push the inner pressure ball 18 and the outer pressure ball 20 to perform local stamping on the tube blank;

[0022] Step 6: Take out the formed tube blank; retract the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19, operate the vertical operating disc 1 to raise the upper clamping ring 23, and take out the formed tube;

[0023] Step 7: The tube blank is transferred to the final forming die, and cooling water is introduced into the cooling water channel 30 to locally cool the tube blank during the final forming process, thereby achieving control of the tube blank wall thickness.

[0024] Between step 4 and step 5, the following steps are added: heating the tube blank; energizing the induction coil 27 to monitor the temperature change of the tube blank.

[0025] Beneficial effects of the present invention:

[0026] 1. The present invention proposes a method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressed forming pipe, which makes the cross-sectional changes of the pipe more flexible and diversified. The present invention uses the synergistic effect of the inner pressure ball and the outer pressure ball to simultaneously produce local convex and local concave features in the cross-sectional area of ​​the pipe blank. If other cross-sectional shapes are required, it is only necessary to change the shape of the pressure ball, allowing the pipe blank to achieve more flexible and diversified cross-sectional designs during the production process, which can meet the customized needs of specific applications, and thus can significantly improve the market competitiveness of the product.

[0027] Second, the cross-sectional shape and wall thickness control method of a large-sized thin-walled pipe hot-pressing forming pipe proposed in the present invention is suitable for processing large-sized pipe blanks with complex cross-sectional shapes. For pipe blanks of specific shapes and diameters, only the clamping grooves of the upper clamping ring and the lower clamping ring need to be changed. The proposed method can improve the stability of the pipe blank during processing.

[0028] 3. The cross-sectional shape and wall thickness control method of a large-size thin-walled pipe hot-pressing formed pipe proposed by the present invention can make the cross-sectional wall thickness distribution of the formed pipe more uniform. By specially designing the cooling water channel of the final forming mold, the specific position of the pipe blank can be quickly cooled during hot-pressing forming, and the fluidity of the material at the specific position of the pipe blank can be improved to coordinate the local large deformation and small fillet filling of the material in the adjacent area, thereby effectively preventing the local thinning and cracking of the pipe blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a three-dimensional schematic diagram of the cross-sectional shape and wall thickness control device structure of a large-size thin-walled pipe hot-pressing forming pipe of the present invention;

[0030] Figure 2 It is a structural three-dimensional exploded schematic diagram of a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressed formed pipe according to the present invention;

[0031] Figure 3 A three-dimensional schematic diagram of an inner extrusion fixing frame of a tube blank annular section control device of a large-size thin-walled tube hot-pressing forming tube section shape and wall thickness control device of the present invention;

[0032] Figure 4 A three-dimensional schematic diagram of an inner extrusion fixing frame of a tube blank annular section control device of a large-size thin-walled tube hot-pressing forming tube section shape and wall thickness control device of the present invention;

[0033] Figure 5 for Figure 2 The enlarged schematic diagram at A in the middle;

[0034] Figure 6 It is a three-dimensional schematic diagram of a partial structure of a limit locking assembly of the present invention;

[0035] Figure 7 for Figure 4 The enlarged schematic diagram of point B in the middle;

[0036] Figure 8 Schematic diagram of the change in the circumferential cross-section of a tube blank in a method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled tube hot-pressed formed by the present invention; (a) is the initial cross-section, (b) is the convex cross-section, and (c) is the concave cross-section;

[0037] Fig. 9 The present invention is a schematic diagram of the cooling water channel arrangement of a final forming die for controlling the annular flow of materials in a method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing.

[0038] In the figure: 1-vertical operating disc; 2-lifting screw; 3-main support plate; 4-round block; 5-positioning rod; 6-blocking ring; 7-horizontal operating disc; 8-transverse screw; 9-horizontal moving support frame; 10-protective ring; 11-horizontal hydraulic cylinder; 12-trapezoidal block; 13-inner pressure ball support plate; 14-inner extrusion fixed frame; 15-slide; 16-slide bar; 17-sliding block; 18-inner pressure ball; 19-vertical hydraulic cylinder; 20-outer pressure ball; 21-local connecting frame; 22-lateral connecting plate; 23-upper clamping ring; 24-lower support ring; 25-stabilizing ring; 26-stabilizing rod; 27-induction coil; 28-mechanism support bottom plate; 29-tube blank; 30-cooling water channel; 31-final forming mold. DETAILED DESCRIPTION

[0039] A device for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe formed by hot air pressure forming comprises a device for controlling the circumferential cross-sectional area of ​​a pipe blank and a final forming die for controlling the circumferential flow of materials.

[0040] The circumferential cross-section control device comprises a lifting component, a lateral movement component, an inner extrusion component, an outer extrusion component, a limit locking component and a temperature control component.

[0041] The lifting assembly includes a vertical operating disc 1, a lifting screw 2, a main support plate 3, a round block 4, a positioning rod 5, and a blocking ring 6. The vertical operating disc 1 is operated to rotate the lifting screw 2, thereby driving the main support plate 3 to rise and fall. The bottom of the lifting screw 2 contacts the round block 4, and the round block 4 is fixed to the bottom of the device. The positioning rod 5 is used to improve the stability of the lifting of the main support plate 3 and prevent deviation, and the blocking ring 6 has a restraining effect on the lifting of the main support plate 3.

[0042] The lateral movement assembly includes a horizontal operating disc 7, a lateral movement screw 8, a horizontal movement support frame 9, and a protective ring 10. The horizontal operating disc 7 is operated to drive the lateral movement screw 8 to rotate, thereby driving the horizontal movement support frame 9 to move horizontally, and the protective ring 10 ensures the stability of the rotation of the lateral movement screw 8.

[0043] The internal extrusion assembly includes a horizontal hydraulic cylinder 11, a trapezoidal block 12, an internal pressure ball support plate 13, an internal extrusion fixed frame 14, a slide 15, a slide bar 16, a slider 17, and an internal pressure ball 18. The slider 17 is connected to the internal pressure ball support plate 13 and moves up and down in the slide 14. The horizontal hydraulic cylinder 11 pushes the trapezoidal block 12 to move horizontally, and the internal pressure ball support plate 13 moves up and down under the push of the trapezoidal block 12, thereby driving the internal pressure ball 18 to move up and down.

[0044] The external extrusion assembly includes a vertical hydraulic cylinder 19 and an external pressure ball 20. The vertical hydraulic cylinder 19 drives the external pressure ball 20 to move up and down.

[0045] The position limiting and locking assembly includes a local connecting frame 21, a transverse connecting plate 22, an upper clamping ring 23, a lower support ring 24, a stabilizing ring 25, and a stabilizing rod 26. The local connecting frame 21 drives the transverse connecting plate 22 to move up and down, thereby driving the upper clamping ring 23 to move up and down. The upper clamping ring 23 and the lower support ring 24 work together to achieve position limiting and locking of the tube blank. The stabilizing ring 25 and the stabilizing rod 26 control the stability of the upper clamping ring 23 in the up and down movement to prevent deviation.

[0046] The temperature control component is an induction coil 27 .

[0047] A method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing, specifically comprising the following steps:

[0048] Step 1: Perform cross-sectional analysis on the target pipe to determine the location and shape of the local deformation of the pipe blank. Through cross-sectional analysis of the pipe, design the shape and size of the inner and outer pressure balls, and determine the size and feed rate of the horizontal and vertical hydraulic cylinders.

[0049] Step 2: Design the upper clamping ring and the lower support ring. According to the cross-sectional shapes of the two ends of the tube, the clamping grooves of the upper clamping ring and the lower support ring are reasonably designed to ensure that the upper clamping ring and the lower support ring can effectively lock the tube when closed.

[0050] Step 3: Design of the water channel of the final forming mold. According to the thermodynamic simulation calculation, cooling water channels are set at appropriate parts of the mold so that the tube blank can be locally cooled during the final forming process.

[0051] Step 4: Assemble the tube blank. Place the tube blank on the support ring, and operate the vertical operating disc to lock the upper clamping ring on the tube blank. Operate the horizontal operating disc to move the horizontal hydraulic cylinder to the part of the tube that needs local deformation.

[0052] Step 5: Heating the tube. The induction coil is energized to monitor the temperature change of the tube. For some materials with relatively high elongation at room temperature, this step can be omitted.

[0053] Step 6: Local stamping of the tube. When the tube is heated to a suitable temperature, the induction coil is powered off. The horizontal hydraulic cylinder and the vertical hydraulic cylinder are started to push the inner pressure ball and the outer pressure ball to perform local stamping on the tube.

[0054] Step 7: Take out the formed tube. Retract the horizontal hydraulic cylinder and the vertical hydraulic cylinder, operate the vertical operating disc to raise the upper clamping ring, and take out the formed tube.

[0055] Step 8: The tube is transferred to the final forming mold, and cooling water is introduced into the cooling water channel to locally cool the tube during the final forming process, thereby achieving control of the tube wall thickness.

[0056] The technical solution of this solution will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0057] Specific implementation method 1: Combination Figures 1 to 9 Description. The present invention proposes a method for controlling the cross section of a large-sized thin-walled pipe formed by hot air pressing. The method is performed according to the following steps:

[0058] Step 1: Perform cross-sectional analysis on the target pipe to determine the location and shape of the local deformation of the pipe blank. By analyzing the cross-sectional shape of the pipe, the shape and size of the inner pressure ball 18 and the outer pressure ball 20 are designed, and the size and feed rate of the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are determined.

[0059] Step 2: Design of the upper clamping ring 23 and the lower support ring 24. According to the cross-sectional shapes of the two ends of the tube blank, the clamping grooves of the upper clamping ring and the lower support ring are reasonably designed to ensure that the upper clamping ring 23 and the lower support ring 24 effectively lock the tube blank 29 when closed.

[0060] Step 3: Design of the water channel of the final forming mold: According to thermodynamic simulation calculations, cooling water channels 30 are arranged at appropriate locations of the final forming mold 31 so that the tube blank 29 can be locally and rapidly cooled during the hot air pressure forming process.

[0061] Step 4: Assembling the tube blank 29. Place the tube blank 29 on the lower support ring 24, and operate the vertical operating disc 1 to lock the upper clamping ring 23 on the tube blank 29. Operate the horizontal operating disc 7 to move the horizontal hydraulic cylinder 11 to the part of the tube blank 29 that needs to be partially deformed.

[0062] Step 5: Heating the tube blank 29. The induction coil 27 is energized to monitor the temperature change of the tube blank.

[0063] Step 6: Local stamping of the tube blank 29. After the tube blank 29 is heated to a suitable temperature, the induction coil 27 is powered off. The horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are started to push the inner pressure ball 18 and the outer pressure ball 20 to perform local stamping on the tube blank 29, forming local convex and concave cross-sectional features, such as Figure 8 shown.

[0064] Step 7: Take out the formed tube blank 29. Retract the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19, operate the vertical operating disc 1 to raise the upper clamping ring 23, and take out the formed tube blank.

[0065] Step eight, the tube blank 29 is transferred to the final forming die 31, and cooling water is introduced into the cooling water channel 30. During the hot air pressing forming process, the tube blank 29 is locally cooled to improve the annular fluidity of the material at this position to coordinate the material filling of the adjacent fillet area, thereby achieving control of the wall thickness of the tube blank 29.

[0066] Specific implementation method 2: For some materials with relatively high elongation at room temperature, the step of heating the tube blank 29 in step 5 can be eliminated. The other steps are the same as those in specific implementation method 1.

[0067] Specific implementation method three: For preformed tube blanks with high surface quality requirements, in step one, a cross-sectional analysis can be performed on the preformed tube blank to determine the position and shape of the local deformation of the preformed tube blank. Through the cross-sectional analysis of the preformed tube blank, the shape and size of the inner pressure ball 18 and the outer pressure ball 20 are designed, and the materials of the inner pressure ball 18 and the outer pressure ball 20 are designed. High-performance alloy steel is selected as the material of the inner pressure ball 18 and the outer pressure ball 20. Through precision grinding and polishing processes, the surface finish is improved to less than Ra0.1μm, and then the size and feed rate of the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are determined. In step five, the tube blank 29 is partially stamped. After the tube blank 29 is heated to a suitable temperature, the induction coil 27 is powered off. The horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are started to push the inner pressure ball 18 and the outer pressure ball 20 to perform local stamping on the tube blank 29. The contact state between the inner pressure ball 18 and the outer pressure ball 20 and the pipe 29 is monitored in real time by the sensor, and the advancing speed of the sensor is adjusted according to the monitoring result to ensure the forming accuracy. The other steps are the same as those in the first embodiment.

Claims

1. A device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing, characterized in that: The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe hot-pressing forming pipe comprises a pipe blank circumferential cross-sectional control device and a final forming die for controlling the circumferential flow of the material to realize local stamping; The tube blank annular cross-section control device controls the cross-section shape, and includes a lifting assembly, a transverse movement assembly, an inner extrusion assembly, an outer extrusion assembly, and a limit locking assembly; the target tube is fixed by the limit locking assembly, and the inner extrusion assembly and the outer extrusion assembly are moved to the position to be stamped by the lifting assembly and the transverse movement assembly for stamping; The final forming die (31) is used to control the wall thickness, and its shape is in accordance with the target stamping shape. A cooling water channel (30) is arranged on it to achieve local rapid cooling during the hot air pressure forming process.

2. The device for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe formed by hot air pressing according to claim 1 is characterized in that: The lifting assembly comprises a vertical operating disc (1), a lifting screw (2), a main support plate (3), a round block (4), a positioning rod (5) and a blocking ring (6); one end of the lifting screw (2) is connected to the vertical operating disc (1), and the other end contacts the round block (4) after passing through the main support plate (3); the round block (4) is fixed on the mechanism support base plate (28); two ends of the main support plate (3) pass through a positioning rod (5) respectively; one end of the positioning rod (5) is fixed on the mechanism support base plate (28), and the other end of the positioning rod (5) is installed with a blocking ring (6); the vertical operating disc (1) is manipulated to rotate the lifting screw (2), thereby driving the main support plate (3) to rise and fall.

3. The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to claim 1, characterized in that: The transverse movement assembly comprises a horizontal operating disc (7), a transverse movement screw (8), a horizontal moving support frame (9), and a protective ring (10); one end of the transverse movement screw (8) is connected to the horizontal operating disc (7), and the other end is connected to the protective ring (10) after passing through the horizontal moving support frame (9); the horizontal moving support frame (9) is in an inverted L shape, and an external extrusion assembly is installed on its top surface; the horizontal operating disc (7) is operated to drive the transverse movement screw (8) to rotate, thereby driving the horizontal moving support frame (9) to move horizontally, and the protective ring (10) is used to limit and ensure the stability of the rotation of the transverse movement screw (8).

4. The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to claim 1, characterized in that: The external extrusion assembly comprises a vertical hydraulic cylinder (19) and an external pressure ball (20); the vertical hydraulic cylinder (19) drives the external pressure ball (20) to perform lifting motion.

5. The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to claim 1, characterized in that: The internal extrusion assembly comprises a horizontal hydraulic cylinder (11), a trapezoidal block (12), an internal pressure ball support plate (13), an internal extrusion fixed frame (14), a slide groove (15), a slide rod (16), a slide block (17) and an internal pressure ball (18); the internal extrusion fixed frame (14) is provided with slide grooves (15) on both sides at one end, and the horizontal hydraulic cylinder (11) is installed in the other end; one end of the horizontal hydraulic cylinder (11) is connected to one side of the trapezoidal block (12), and the other side of the trapezoidal block (12) is connected to the inner pressure ball (18); The inner pressure ball support plate (13) touches the inner pressure ball support plate (13); two ends of the inner pressure ball support plate (13) are connected to sliders (17), the slide bar (16) is fixed in the slide groove (15), and the slider (17) moves on the slide bar (16); (18) is fixed on the inner pressure ball support plate (13); the horizontal hydraulic cylinder (11) pushes the trapezoidal block (12) to move horizontally, and the inner pressure ball support plate (13) performs lifting movement under the push of the trapezoidal block (12), thereby driving the inner pressure ball (18) to perform lifting movement.

6. The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to claim 1, characterized in that: The position limiting and locking assembly comprises a partial connecting frame (21), a transverse connecting plate (22), an upper clamping ring (23), a lower supporting ring (24), a stabilizing ring (25), and a stabilizing rod (26); the partial connecting frame (21) is fixed on the main supporting plate (3) of the lifting assembly; the partial connecting frame (21) is fixedly connected to one end of the transverse connecting plate (22), and the other end of the transverse connecting plate (22) is fixedly connected to the upper clamping ring (23); the lower supporting ring (24) is fixed on the mechanism supporting bottom plate (28); the partial connecting frame (21) drives the transverse connecting plate (22) to move up and down, thereby driving the upper clamping ring (23) to move up and down; the upper clamping ring (23) and the lower supporting ring (24) work together to achieve position limiting and locking of the tube blank; the stabilizing ring (25) is fixed on the upper clamping ring (23), and the stabilizing rod (26) is fixed on the mechanism supporting bottom plate; the stabilizing ring (25) and the stabilizing rod (26) control the stability of the upper clamping ring (23) in the up and down movement to prevent deviation.

7. The device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to any one of claims 1 to 6, characterized in that: The tube blank annular cross-section control device further comprises a temperature control component; the temperature control component is an induction coil (27).

8. A method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing, characterized in that: The method is realized by the device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressure forming according to any one of claims 1 to 7, specifically comprising the following steps: Step 1: Perform cross-sectional analysis on the target pipe to determine the position and shape of the local deformation of the pipe blank; through the cross-sectional analysis of the pipe, design the shape and size of the inner pressure ball (18) and the outer pressure ball (20), and determine the size and feed rate of the horizontal hydraulic cylinder (11) and the vertical hydraulic cylinder (19); Step 2, designing an upper clamping ring (23) and a lower support ring (24); designing clamping grooves of the upper clamping ring (23) and the lower support ring (24) according to the cross-sectional shapes of the two ends of the tube blank, so as to ensure that the upper clamping ring (23) and the lower support ring (24) effectively lock the tube blank when closed; Step 3: Design of the water channel of the final forming mold; according to thermodynamic simulation calculation, cooling water channels (30) are arranged at the two side edges of the local raised fillet area of ​​the final forming mold cavity, so that the tube blank can be locally cooled during the final forming process; Step 4: Assembling the tube blank; placing the tube blank on the lower support ring (24), operating the vertical operating disc (1) to lock the upper clamping ring (23) on the tube blank; operating the horizontal operating disc (7) to move the horizontal hydraulic cylinder to the part of the tube that needs local deformation; Step 5: local stamping of the tube blank; after the tube blank is heated to the set temperature, the induction coil (27) is powered off; the horizontal hydraulic cylinder (11) and the vertical hydraulic cylinder (19) are started to push the inner pressure ball (18) and the outer pressure ball (20) respectively to perform local stamping on the tube blank; Step 6: Take out the formed tube blank; retract the horizontal hydraulic cylinder (11) and the vertical hydraulic cylinder (19), operate the vertical operating disc (1) to raise the upper clamping ring (23), and take out the formed tube; Step 7: The tube blank is transferred to the final forming die, and cooling water is introduced into the cooling water channel (30) to locally cool the tube blank during the final forming process, thereby achieving control of the tube blank wall thickness.

9. The method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe formed by hot air pressing according to claim 8, characterized in that: Between step 4 and step 5, the following steps are added: heating the tube blank; energizing the induction coil (27) to monitor the temperature change of the tube blank.

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