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

Abstract

The utility model belongs to the technical field of annular section shape and wall thickness control of a metal thin-wall pipe fitting, and provides a section shape and wall thickness control device for a hot air pressure formed pipe fitting of a large-size thin-wall pipe fitting. 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 is locally raised and locally recessed at the same time, and the stability of the pipe blank in the machining process is improved only by changing the 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 utility model relates to the technical field of controlling the circumferential cross-sectional shape and wall thickness of metal thin-walled pipe fittings, and particularly relates to a device for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe fitting in hot gas pressure forming. Background Technique

[0002] The hot gas pressure forming process of pipe materials is an efficient metal processing technology, which is widely used in the forming of metal thin-walled pipe fittings with complex special-shaped cross-sections. In the manufacturing fields such as aerospace and automobiles, the hot gas pressure forming process of pipe materials can be used to produce lightweight, high-strength components with complex cross-sectional characteristics. For example, when large-size complex special-shaped cross-section thin-walled pipe fittings are used in the wing, fuselage and tail parts of an aircraft in the aerospace field, the weight can be reduced while ensuring its structural strength and stiffness. With the rapid development of the automobile industry, components such as the chassis and body structure parts of automobiles need to be further lightened and the strength improved to enhance the power performance and safety of the automobiles. Therefore, the hot gas pressure forming process of pipe materials has outstanding advantages in the forming of large-size complex special-shaped cross-section thin-walled components in the aerospace and automobile industries.

[0003] Before the hot gas pressure forming of a large-size thin-walled pipe fitting with a complex special-shaped cross-section, the pipe blank placed in the hot gas pressure forming die often undergoes multiple pre-treatment processes such as bending, flattening, and pre-forming. At the beginning of the hot gas pressure forming, the cross-sectional outer contour at different axial positions of the pipe blank is smaller than the cross-sectional contour at the corresponding position in the die cavity, and the degree of difference between the cross-sectional shapes of the pipe blank at each position and the cross-sectional shape at the corresponding position in the die cavity is different. The hot gas pressure forming process of the pipe fitting is essentially a process in which the cross-section of the pipe blank approaches the cross-section of the corresponding die cavity, and this process directly determines the quality of the formed pipe fitting at each part and the wall thickness distribution, etc. Therefore, it is necessary to perform reasonable pre-forming on the original pipe blank to achieve a good matching relationship between the cross-sectional shape of the preform and the cross-section of the corresponding die cavity.

[0004] In addition, in the hot state, because the yield strength of the material is low and its load transfer ability is also weakened, it is difficult to achieve large load transfer between adjacent regions of the pipe blank, resulting in tensile thinning and compressive wrinkling. When the diameter of the pipe blank is large, the deformations at different circumferential positions of the pipe blank do not affect each other. Although the pipe blank is a closed structure, it can no longer transfer the circumferential stress, and the deformation of the pipe blank becomes, to a certain extent, the deformation of a slab. That is, when there is a large amount of material stored in a certain area of the pipe blank, it is easy to form wrinkles that cannot be flattened after fitting against the inner wall of the die, and when there is less material stored in a certain area of the pipe blank, it is easy to crack due to excessive thinning of the material. Since the pipe blank cannot transfer materials through the mutual load transfer of materials in adjacent regions in the hot state, it is very easy to have serious local wrinkling and local thinning defects due to unreasonable material distribution at each part of the initial pipe blank.

[0005] In order to solve the problems that when a large-size thin-walled pipe fitting is rapidly formed by hot gas pressure in the length direction and diameter direction, it is difficult to match the shape of the preform with the mold cavity, and it is difficult for the materials in adjacent regions of the pipe blank to transfer to each other under the hot state, and serious local wrinkles and local thinning defects are likely to occur, a method for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe fitting formed by hot gas pressure is required. Summary of the Utility Model

[0006] The purpose of the present utility model is to provide a device and method for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe fitting formed by hot gas pressure, 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 difficult transfer of materials in adjacent regions of the pipe blank under the hot state.

[0007] The technical solution of the present utility model is as follows: A device for controlling the cross-sectional shape and wall thickness of a large-size thin-walled pipe fitting formed by hot gas pressure includes a circumferential cross-section control device for the pipe blank and a final forming die for controlling the circumferential flow of materials to achieve local stamping.

[0008] The circumferential cross-section control device for the pipe blank controls the cross-sectional shape, and it includes a lifting component, a transverse movement component, an inner extrusion component, an outer extrusion component, and a limit locking component; the target pipe is fixed by the limit locking component, and the inner extrusion component and the outer extrusion component are moved to the position to be stamped through the lifting component and the transverse movement component for stamping.

[0009] The final forming die is used to control the wall thickness, and its shape is conformable to the target stamping shape, and a cooling water channel 30 is arranged thereon for achieving rapid local cooling during the hot gas pressure forming process.

[0010] The lifting component includes a vertical operation 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 operation 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 bottom plate 28; both 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 bottom plate 28, and a blocking ring 6 is installed at the other end of the positioning rod 5; operating the vertical operation disc 1 to rotate the lifting screw 2, thereby driving the main support plate 3 to lift and lower.

[0011] The transverse movement component includes a horizontal operation disc 7, a transverse movement screw 8, a horizontal movement support frame 9, and a protection ring 10; one end of the transverse movement screw 8 is connected to the horizontal operation disc 7, and the other end is connected to the protection ring 10 after passing through the horizontal movement support frame 9; the horizontal movement support frame 9 is in an inverted L shape, and the outer extrusion component is installed on its top surface; operating the horizontal operation disc 7 to drive the transverse movement screw 8 to rotate, thereby driving the horizontal movement support frame 9 to move horizontally, and the protection ring 10 is used for limiting and ensuring the stability of the rotation of the transverse movement screw 8.

[0012] The described 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.

[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 chute 15, a sliding rod 16, a slider 17, and an internal pressure ball 18; on both sides at one end of the internal extrusion fixed frame 14, there are chutes 15, and a horizontal hydraulic cylinder 11 is installed inside 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; both ends of the internal pressure ball support plate 13 are connected to the slider 17, the sliding rod 16 is fixed inside the chute 15, and the slider 17 moves on the sliding rod 16; the internal pressure ball support plate 13 is fixed; the horizontal hydraulic cylinder 11 pushes the trapezoidal block 12 to move horizontally, and the internal pressure ball support plate 13 makes a lifting movement under the push of the trapezoidal block 12, thereby driving the internal pressure ball 18 to make a lifting movement.

[0014] The limit locking assembly includes a partial connecting frame 21, a transverse connecting plate 22, an upper pressing 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; one end of the partial connecting frame 21 is fixedly connected to the transverse connecting plate 22, and the other end of the transverse connecting plate 22 is fixedly connected to the upper pressing ring 23; the lower support ring 24 is fixed on 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 pressing ring 23 to move up and down; the upper pressing ring 23 and the lower support ring 24 jointly act to limit and lock the tube blank; the stabilizing ring 25 is fixed on the upper pressing 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 up and down movement of the upper pressing ring 23 to prevent deviation.

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

[0016] The beneficial effects of the present utility model are as follows:

[0017] First, a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting by hot gas pressure forming proposed by the present utility model makes the cross-sectional change of the pipe more flexible and diversified. Through the synergistic effect of the internal pressure ball and the external pressure ball, local protrusions and local depressions are simultaneously generated on the cross-section of the tube blank. If other cross-sectional shapes are needed, only the shape of the pressure ball needs to be changed. It allows for a more flexible and diversified cross-sectional design during the production process of the tube blank, can meet the customized requirements of specific applications, and thus can significantly improve the market competitiveness of the product.

[0018] II. A device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming proposed by the present utility model is applicable to the processing of large-sized pipe blanks with complex cross-sectional shapes. For pipe blanks with specific shapes and diameters, only the clamping grooves of the upper pressing ring and the lower pressing ring need to be changed. By the proposed method, the stability in the process of pipe blank processing can be improved.

[0019] III. A device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming proposed by the present utility model can make the cross-sectional wall thickness distribution of the formed pipe fitting more uniform. Through the special design of the cooling water channels of the final forming die, the local area of the pipe blank can be rapidly cooled during hot gas pressure forming, and the fluidity of the material at specific positions of the pipe blank is improved to coordinate the local large deformation and small-round-corner filling of the material in its adjacent areas, thereby effectively preventing the phenomenon of local thinning and cracking of the pipe blank. Brief Description of the Drawings

[0020] Figure 1 is a three-dimensional schematic diagram of the structure of a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming according to the present utility model;

[0021] Figure 2 is a three-dimensional exploded schematic diagram of the structure of a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming according to the present utility model;

[0022] Figure 3 is a three-dimensional schematic diagram of the inner extrusion fixing frame of the pipe blank circumferential cross-section control device of a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming according to the present utility model;

[0023] Figure 4 is a three-dimensional schematic diagram of the inner extrusion fixing frame of the pipe blank circumferential cross-section control device of a device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting in hot gas pressure forming according to the present utility model;

[0024] Figure 5 is Figure 2 the enlarged schematic diagram at A in

[0025] Figure 6 is a three-dimensional schematic diagram of a partial structure of the limit locking component of the present utility model;

[0026] Figure 7 is Figure 4 the enlarged schematic diagram at B in

[0027] Figure 8 is the schematic diagram of the circumferential cross-section change of the pipe blank of the present utility model; (a) is the initial cross-section, (b) is the convex cross-section, and (c) is the concave cross-section;

[0028] Figure 9Schematic diagram of the cooling water channel arrangement of the final forming die for controlling the circumferential flow of the control material of the present utility model.

[0029] In the figure: 1 - vertical operation disc; 2 - lifting screw; 3 - main support plate; 4 - round block; 5 - positioning rod; 6 - blocking ring; 7 - horizontal operation disc; 8 - transverse movement screw; 9 - horizontal movement support frame; 10 - protection ring; 11 - horizontal hydraulic cylinder; 12 - trapezoidal block; 13 - inner pressure ball support plate; 14 - inner extrusion fixing frame; 15 - chute; 16 - sliding rod; 17 - slider; 18 - inner pressure ball; 19 - vertical hydraulic cylinder; 20 - outer pressure ball; 21 - local connecting frame; 22 - transverse connecting plate; 23 - upper pressing 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 die. Specific implementation mode

[0030] A device for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting by hot gas pressure forming includes a circumferential cross-section control device for the pipe blank and a final forming die for controlling the circumferential flow of the material.

[0031] The circumferential cross-section control device includes a lifting assembly, a transverse movement assembly, an inner extrusion assembly, an outer extrusion assembly, a limit locking assembly, and a temperature control assembly.

[0032] The lifting assembly includes a vertical operation disc 1, a lifting screw 2, a main support plate 3, a round block 4, a positioning rod 5, and a blocking ring 6. Operating the vertical operation disc 1 rotates the lifting screw 2, thereby driving the main support plate 3 to lift and lower. The bottom of the lifting screw 2 contacts the round block 4, and the round block 4 is fixed at 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 restricts the lifting of the main support plate 3.

[0033] The transverse movement assembly includes a horizontal operation disc 7, a transverse movement screw 8, a horizontal movement support frame 9, and a protection ring 10. Operating the horizontal operation disc 7 drives the transverse movement screw 8 to rotate, thereby driving the horizontal movement support frame 9 to move horizontally, and the protection ring 10 ensures the stability of the rotation of the transverse movement screw 8.

[0034] The inner extrusion assembly includes a horizontal hydraulic cylinder 11, a trapezoidal block 12, an inner pressure ball support plate 13, an inner extrusion fixing frame 14, a chute 15, a sliding rod 16, a slider 17, and an inner pressure ball 18. The slider 17 is connected to the inner pressure ball support plate 13 and moves up and down in the chute 14. The horizontal hydraulic cylinder 11 pushes the trapezoidal block 12 to move horizontally, and the inner pressure ball support plate 13 moves up and down under the push of the trapezoidal block 12, thereby driving the inner pressure ball 18 to move up and down.

[0035] The described 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.

[0036] The described limit locking assembly includes a partial connecting frame 21, a horizontal connecting plate 22, an upper pressing ring 23, a lower support ring 24, a stabilizing ring 25, and a stabilizing rod 26. The partial connecting frame 21 drives the horizontal connecting plate 22 to move up and down, thereby driving the upper pressing ring 23 to move up and down. The upper pressing ring 23 and the lower support ring 24 work together to limit and lock the tube blank. The stabilizing ring 25 and the stabilizing rod 26 control the stability of the up and down movement of the upper pressing ring 23 to prevent deviation.

[0037] The described temperature control component is an induction coil 27.

[0038] A method for controlling the cross-sectional shape and wall thickness of a large-sized thin-walled pipe fitting during hot gas pressure forming specifically includes the following steps:

[0039] Step 1: Conduct a cross-sectional analysis of the target pipe material to determine the position and shape of the local deformation of the tube blank. Through the cross-sectional analysis of the pipe material, design the shape and size of the internal pressure ball and the external pressure ball, and determine the size and feed of the horizontal hydraulic cylinder and the vertical hydraulic cylinder.

[0040] Step 2: Design the upper pressing ring and the lower support ring. According to the cross-sectional shape at both ends of the tube blank, reasonably design the clamping grooves of the upper pressing ring and the lower support ring to ensure effective locking of the tube blank when the upper pressing ring and the lower support ring are closed.

[0041] Step 3: Design the water circuit of the final forming die. According to the thermodynamic simulation calculation, set cooling water channels at appropriate parts of the die so that the tube blank can be locally cooled during the final forming process.

[0042] Step 4: Assemble the tube blank. Place the tube blank on the support ring, and operate the vertical operation disc to lock the tube blank with the upper pressing ring. Operate the horizontal operation disc to move the horizontal hydraulic cylinder to the position where the tube material needs local deformation.

[0043] Step 5: Heat the tube blank. The induction coil is energized, and the temperature change of the tube blank is monitored. For some materials with relatively high elongation at room temperature, this step can be cancelled.

[0044] Step 6: Locally punch the tube blank. After the tube blank is heated to the appropriate temperature, the induction coil is powered off. Start the horizontal hydraulic cylinder and the vertical hydraulic cylinder, and respectively push the internal pressure ball and the external pressure ball to locally punch the tube blank.

[0045] Step 7: Remove the formed tube blank. Retract the horizontal hydraulic cylinder and the vertical hydraulic cylinder, operate the vertical operation disc to raise the upper pressing ring, and remove the formed pipe material.

[0046] Step VIII: Transfer the tube blank to the final forming die, introduce cooling water into the cooling water channels, and locally cool the tube blank during the final forming process, thereby achieving control over the wall thickness of the tube blank.

[0047] The technical solution of this solution will be further described below in conjunction with the drawings and through specific embodiments.

[0048] Specific Embodiment 1: In conjunction with Figures 1 to 9 Description. A method for controlling the cross-section of a large-sized thin-walled pipe fitting by hot gas pressure forming proposed by the present utility model is carried out according to the following steps:

[0049] Step I: Conduct a cross-section analysis of the target pipe to determine the position and shape of the local deformation of the tube blank. Through the cross-section analysis of the pipe, design the shapes and sizes of the internal pressure ball 18 and the external pressure ball 20, and determine the sizes and feed amounts of the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19.

[0050] Step II: Design the upper clamping ring 23 and the lower support ring 24. According to the cross-section shapes at both ends of the tube blank, reasonably design the clamping grooves of the upper clamping ring and the lower support ring to ensure that the upper clamping ring 23 and the lower support ring 24 effectively lock the tube blank 29 when closed.

[0051] Step III: Design the water circuit of the final forming die. According to the thermodynamic simulation calculation, set the cooling water channels 30 at appropriate positions on the final forming die 31 so that the tube blank 29 can be locally and rapidly cooled during the hot gas pressure forming process.

[0052] Step IV: Assemble the tube blank 29. Place the tube blank 29 on the lower support ring 24, and operate the vertical operation disc 1 to lock the tube blank 29 with the upper clamping ring 23. Operate the horizontal operation disc 7 to move the horizontal hydraulic cylinder 11 to the position where the tube blank 29 needs local deformation.

[0053] Step V: Heat the tube blank 29. Energize the induction coil 27 and monitor the temperature change of the tube blank.

[0054] Step VI: Locally stamp the tube blank 29. After the tube blank 29 is heated to an appropriate temperature, the induction coil 27 is powered off. Start the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19, and respectively push the internal pressure ball 18 and the external pressure ball 20 to locally stamp the tube blank 29 to form local protrusion and depression cross-section features, as Figure 8 shown.

[0055] Step VII: Take out the formed tube blank 29. Retract the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19, and operate the vertical operation disc 1 to raise the upper clamping ring 23 to take out the formed tube blank.

[0056] Step VIII. 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 gas pressure forming process, the tube blank 29 is locally cooled to improve the circumferential fluidity of the material at this position to coordinate the material filling in its adjacent fillet areas, thereby achieving the control of the wall thickness of the tube blank 29.

[0057] Specific Embodiment 2: For some materials with relatively high elongation at normal temperature, the heating link of the tube blank 29 in Step V can be cancelled. Other steps are the same as those in Specific Embodiment 1.

[0058] Specific Embodiment 3: For preformed tube blanks with high surface quality requirements, in Step I, cross-section analysis of the preformed tube blank can be carried out to determine the position and shape of the local deformation of the preformed tube blank. Through the cross-section analysis of the preformed tube blank, the shapes and sizes of the internal pressure ball 18 and the external pressure ball 20 are designed, and at the same time, the materials of the internal pressure ball 18 and the external pressure ball 20 are designed. High-performance alloy steel is selected as the material of the internal pressure ball 18 and the external pressure ball 20, and through precision grinding and polishing processes, its surface finish is improved to below Ra0.1μm, and then the sizes and feed amounts of the horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are determined. In Step V, local stamping of the tube blank 29. After the tube blank 29 is heated to an appropriate temperature, the induction coil 27 is powered off. The horizontal hydraulic cylinder 11 and the vertical hydraulic cylinder 19 are started to push the internal pressure ball 18 and the external pressure ball 20 respectively to perform local stamping on the tube blank 29. The contact state between the internal pressure ball 18 and the external pressure ball 20 and the tube material 29 is monitored in real time by sensors, and the propulsion speed of the sensors is adjusted according to the monitoring results to ensure the forming accuracy. Other steps are the same as those in Specific Embodiment 1.

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-sized 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 slider (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 end of the trapezoidal block (12) is connected to the inner pressure ball support plate (13); the inner pressure ball (18) is provided with a slide groove (15) on both sides at one end of the internal extrusion fixed frame (14), ... inner pressure ball (18) is provided with a slide groove (15) on both sides at one end of the internal extrusion fixed frame (14), and the inner pressure ball (18) is provided with a slide groove (15) on both sides at the other end of the internal extrusion fixed frame (14); the inner pressure ball (18) is provided with a slide groove (15) on both sides at one end of the internal extrusion fixed frame (14), and the inner pressure ball (18) is provided with a slide groove (15) on both sides at the other end of the internal extrusion fixed frame (14); the inner pressure ball (18) is provided with a slide groove (15) on both sides at one end of the internal extrusion fixed frame (14), and the inner pressure ball (18) The inner pressure ball support plate (13) is in contact with the side; the two ends of the inner pressure ball support plate (13) are connected to the slide block (17); the slide bar (16) is fixed in the slide groove (15); the slide block (17) moves on the slide bar (16); the inner pressure ball support plate (13) is fixed; the horizontal hydraulic cylinder (11) pushes the trapezoidal block (12) to move horizontally, and the inner pressure ball support plate (13) is lifted and lowered under the push of the trapezoidal block (12), thereby driving the inner pressure ball (18) to lift and lower.

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 limit 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 limit locking on 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).

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