INTEGRATED VARIABLE-AXIS FREE-BEND FORMING APPARATUS FOR TUBES

Abstract

An integrated variable-axis free-bend forming apparatus for tubes includes a base movement module used to provide translational degrees of freedom for a bending die in X and Y directions, and a precision adjustment module including state switching modules and auxiliary adjustment modules. By changing positions of rotary motors in the state switching modules and driven shafts in the auxiliary adjustment modules, switching of the bending die among three statesfollow-up, semi-active, and activecan be achieved, thereby adjusting the number of processing axes of the apparatus. A fixed guide module is located at a rear side of a bending processing module and remains stationary during processing. A front-end arc surface of a guide mechanism contacts a guide fin to control the processing posture of the bending die in the follow-up and semi-active states. This apparatus improves quality and efficiency of tube bending processing while also expanding an applicable range.

Claims

1. An integrated variable-axis free-bend forming apparatus for tubes, comprising: a base movement module (1), configured to adjust translational degrees of freedom of the apparatus along an X axis and a Y axis; a precision adjustment module (2), fixedly connected to the base movement module (1), and the precision adjustment module (2) being configured to switch a processing state of a bending processing module (4) to thereby adjust a number of processing axes of the apparatus; wherein the precision adjustment module (2) comprises: a main body installation module (23), two state switching modules (24), and two auxiliary adjustment modules (25); the main body installation module (23) comprises: a main body support plate (39), a cross roller bearing (40), a bending die installation seat (41), and a drive shaft (42); the main body support plate (39) of the main body installation module (23) is fixedly connected to the base movement module (1), the bending processing module (4) is disposed within the bending die installation seat (41), four side surfaces of the bending die installation seat (41) are sequentially defined as an RX side surface, an RY side surface, an A side surface, and a B side surface, the RY side surface of the bending die installation seat (41) is installed on the main body support plate (39) via the cross roller bearing (40), the two state switching modules (24) are respectively defined as an RX-axis state switching module and an RY-axis state switching module, the RX-axis state switching module is installed at the RX side surface of the bending die installation seat (41), the RY-axis state switching module is installed at the RY side surface of the bending die installation seat (41), the two auxiliary adjustment modules (25) are respectively disposed at the A side surface and the B side surface of the bending die installation seat (41), and a driven shaft (37) of each of the two auxiliary adjustment modules (25) is connected to the bending processing module (4); the drive shaft (42) is further fixedly installed at the RY side surface of the bending die installation seat (41); the cross roller bearing (40), an RY side plate of the bending die installation seat (41), the drive shaft (42), and the bending processing module (4) are sequentially arranged in that order along an axial direction of an output shaft of the RY-axis state switching module; and a position where the output shaft of the RY-axis state switching module is fixed to the drive shaft (42) is defined as a third position; wherein each of the two state switching module (24) comprises: a rotary motor (29), a rotary motor installation member (34), and an axial position control assembly; and the rotary motor installation member (34) is installed on a corresponding side surface of the bending die installation seat (41) via an axial position control assembly, the rotary motor (29) is fixedly installed in the rotary motor installation member (34), and the axial position control assembly is configured to adjust an axial displacement of the rotary motor (29) to switch a connection state of an output shaft of the rotary motor (29), thereby switching the processing state of the bending processing module (4); wherein each auxiliary adjustment module (25) comprises: a cylinder (38) and the driven shaft (37), an output shaft of the cylinder (38) is fixedly connected to the driven shaft (37), and the driven shaft (37) is connected to the bending processing module (4); a fixed guide module (3), configured to guide a straight tube blank (5); and the bending processing module (4), installed in the precision adjustment module (2), and the bending processing module (4) being configured to process the straight tube blank (5) to complete free-bend forming of the straight tube blank (5).

2. The integrated variable-axis free-bend forming apparatus for tubes according to claim 1, wherein the base movement module (1) comprises: an X-axis linear translation assembly and a Y-axis linear translation assembly, the Y-axis linear translation assembly is fixedly connected to the X-axis linear translation assembly, and the Y-axis linear translation assembly is fixedly connected to the precision adjustment module (2).

3. The integrated variable-axis free-bend forming apparatus for tubes according to claim 1, wherein the axial position control assembly comprises: a second slide rail (27), a second slider (28), a drive gear (31), a linear rack (32), and a gear motor (35); the linear rack (32) is fixedly connected to the bending die installation seat (41), the gear motor (35) is fixedly connected to the rotary motor installation member (34), an output shaft of the gear motor (35) is coaxially fixed to the drive gear (31), and the drive gear (31) meshes with the linear rack (32) to form a gear-rack pair; the second slide rail (27) is fixedly connected to the bending die installation seat (41), and the second slider (28) is slidably installed on the second slide rail (27); and the gear motor (35) is configured to drive the rotary motor installation member (34) to slide along the axial direction of the output shaft of the rotary motor (29) via the gear-rack pair, and to drive the second slider (28) to slide along the axial direction of the output shaft of the rotary motor (29) within the second slide rail (27).

4. The integrated variable-axis free-bend forming apparatus for tubes according to claim 1, wherein the bending processing module (4) comprises: a bending die (46), a bending die support member (45), guide blocks (48), limit blocks (50), and compression springs (49); the bending die support member (45) is disposed within the bending die installation seat (41) of the precision adjustment module (2), the bending die (46) is rotatably installed within the bending die support member (45); two end portions of the bending die (46) respectively define inward recesses and a middle portion of the bending die (46) defines an axial hole, the straight tube blank (5) is disposed within the axial hole of the middle portion of the bending die (46), an inner side wall of the axial hole of the middle portion of the bending die (46) is arc-shaped and serves as an action surface for the straight tube blank (5); a RX side surface and a RY side surface of the bending die (46) respectively defines axial guide grooves, a corresponding one of the guide blocks (48) is installed in each of the guide grooves, an end of each guide groove is open, a corresponding one of the limit blocks is installed at an end surface of the bending die (46) at an open end of each guide groove, and the compression springs (49) are installed in the guide grooves at two ends of the guide blocks (48) at the RX side surface and the RY side surface of the bending die (46), respectively; an A side surface and a B side surface of the bending die (46) respectively define counterbores; and wherein the output shaft of the state switching module (24) and/or the driven shaft (37) of the auxiliary adjustment module (25) cooperates with the bending die support member (45), a position where the output shaft of the state switching module (24) and/or the driven shaft (37) of the auxiliary adjustment module (25) cooperates with the bending die support member (45) is defined as a first position; or the output shaft of the state switching module (24) and/or the driven shaft (37) of the auxiliary adjustment module (25) cooperates with the bending die (46), the output shaft of the state switching module (24) cooperates with the guide block (48) of the bending die (46), and the driven shaft (37) of the auxiliary adjustment module (25) cooperates with the counterbore on the side surface of the bending die (46), a position where the output shaft and/or the driven shaft (37) cooperates with the bending die (46) is defined as a second position.

5. The integrated variable-axis free-bend forming apparatus for tubes according to claim 4, wherein in the RY-axis state switching module, the rotary motor installation member (34) is further provided with a limit post (54), and when the output shaft of the rotary motor (29) in the RY-axis state switching module is fixedly connected to the bending die support member (45) or the guide block (48) in the bending processing module (4), the limit post (54) is engaged in an RY limit hole on the drive shaft (42).

6. The integrated variable-axis free-bend forming apparatus for tubes according to claim 4, wherein the bending processing module (4) further comprises a guide fin (47), and the guide fin (47) is fixedly installed at an input end portion of the bending die (46).

7. A processing method for free-bend forming of tubes, using the integrated variable-axis free-bend forming apparatus for tubes according to claim 6, and the processing method comprising: when performing three-axis processing of the straight tube blank (5), installing the guide fin (47) in the apparatus, bringing the fixed guide module (3) into close contact with the guide fin (47), controlling the output shafts of both the RX-axis state switching module and the RY-axis state switching module and the driven shafts of the auxiliary adjustment modules (25) at the A side surface and the B side surface to be located at the first position, thereby placing the bending die (46) in a follow-up state, and completing the three-axis processing of the straight tube blank (5); when performing four-axis processing of the straight tube blank (5), installing the guide fin (47) in the apparatus, bringing the fixed guide module (3) into close contact with the guide fin (47), controlling the output shaft of one of the RX-axis state switching module and the RY-axis state switching module to be at the second position, the output shaft of the other state switching module to be at the first position, and the driven shafts of the auxiliary adjustment modules (25) at the A side surface and the B side surface to be at the first position, thereby placing the bending die (46) in a semi-active state, and completing the four-axis processing of the straight tube blank (5); and when performing five-axis processing of the straight tube blank (5), controlling the output shaft of the RX-axis state switching module to be at the first position, the output shaft of the RY-axis state switching module to be at the third position, and the driven shafts of the auxiliary adjustment modules (25) at the A side surface and the B side surface to be at the second position, thereby placing the bending die (46) in an active state, and completing the five-axis processing of the straight tube blank (5).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is a schematic diagram of an integrated variable-axis free-bend forming apparatus for tubes according to an embodiment of the disclosure.

[0030] FIG. 2 is a structural schematic diagram of a base movement module; where (a) is a three-dimensional axonometric view of the base movement module, and (b) is an exploded view of the base movement module.

[0031] FIG. 3 is a schematic diagram of a precision adjustment module.

[0032] FIG. 4 is an exploded view of a state switching module.

[0033] FIG. 5 is a schematic diagram of an auxiliary adjustment module.

[0034] FIG. 6 is an exploded view of a main body installation module.

[0035] FIG. 7 is a structural schematic diagram of a drive shaft; where (a) is a front view of the drive shaft, and (b) is a side view of the drive shaft.

[0036] FIG. 8 is a schematic diagram of a bending processing module; where (a) is a first schematic diagram of the bending processing module, and (b) is a second schematic diagram of the bending processing module.

[0037] FIG. 9 is a schematic diagram of a bending die support member.

[0038] FIG. 10 is a schematic diagram of a bending die assembled with various parts.

[0039] FIG. 11 is a schematic diagram of the bending die; where (a) is a first schematic diagram of the bending die, (b) is a second schematic diagram of the bending die, and (c) is a third schematic diagram of the bending die.

[0040] FIG. 12 is a schematic diagram of a limit block; where (a) is a first schematic diagram of the limit block, and (b) is a second schematic diagram of the limit block.

[0041] FIG. 13 is a schematic diagram of a guide block; where (a) is a first schematic diagram of the guide block, (b) is a second schematic diagram of the guide block, and (c) is a third schematic diagram of the guide block.

[0042] FIG. 14 is a schematic diagram of an axis system in a RX-A direction for the bending processing module and the precision adjustment module.

[0043] FIG. 15 is a structural schematic diagram of a fixed guide module; where (a) is an overall schematic diagram of the fixed guide module, (b) is a first schematic diagram of the guide mechanism, (c) is a second schematic diagram of the guide mechanism, and (d) is a schematic diagram of the guide mechanism fixing member.

[0044] FIG. 16 is a schematic diagram of a state switching module, an auxiliary adjustment module, and a guide fin when a bending die is in a follow-up state; where (a) is a first cross-sectional view of the state switching module and the auxiliary adjustment module when the bending die is in the follow-up state; (b) is a second cross-sectional view of the state switching module and the auxiliary adjustment module when the bending die is in the follow-up state; (c) is an axonometric view of the state switching module and the auxiliary adjustment module when the bending die is in the follow-up state.

[0045] FIG. 17 is a schematic diagram of a state switching module, an auxiliary adjustment module, and a guide fin when a bending die is in a semi-active state; where (a) is a first cross-sectional view of the state switching module and the auxiliary adjustment module when the bending die is in the semi-active state; (b) is a second cross-sectional view of the state switching module and the auxiliary adjustment module when the bending die is in the semi-active state; (c) is an axonometric view of the state switching module and the auxiliary adjustment module when the bending die is in the semi-active state.

[0046] FIG. 18 is a schematic diagram of a state switching module, an auxiliary adjustment module, and a guide fin when a bending die is in an active state; where (a) is a cross-sectional view of the state switching module and the auxiliary adjustment module when the bending die is in the active state; (b) is an axonometric view of the state switching module and the auxiliary adjustment module when the bending die is in the active state.

[0047] FIG. 19 is a cross-sectional view of an overall structure of the apparatus proposed by the disclosure.

[0048] FIG. 20 is a processing schematic diagram of the apparatus proposed by the disclosure in the follow-up state.

[0049] Reference Numerals: 1. base movement module, 2. precision adjustment module, 3. fixed guide module, 4. bending processing module, 5. straight tube blank, 6. Y-axis motor, 7. motor installation seat, 8. vertical secondary support plate, 9. X-axis motor, 10. support beam, 11. motor installation plate, 12. first slider, 13. first slide rail, 14. horizontal support plate, 15. ball screw, 16. vertical primary support plate, 17. tail end bearing seat, 18. nut fixing seat, 19. screw nut, 20. front end bearing seat, 21. first key, 22. coupling (i.e., coupler), 23. main body installation module, 24. state switching module, 25. auxiliary adjustment module, 26. slide rail installation member, 27. second slide rail, 28. second slider, 29. rotary motor, 30. second key, 31. drive gear, 32. linear rack, 33. rack installation member, 34. rotary motor installation member, 35. gear motor, 36. gear motor installation member, 37. driven shaft, 38. cylinder, 39. main body support plate, 40. cross roller bearing, 41. bending die installation seat, 42. drive shaft, 43. thrust bearing, 44. flange bearing, 45. bending die support member, 46. bending die, 47. guide fin, 48. guide block, 49. compression spring, 50. limit block, 51. third key, 52. guide mechanism, 53. guide mechanism fixing member, 54. limit post.

DETAILED DESCRIPTION OF EMBODIMENTS

[0050] The disclosure is described in further detail below with reference to the accompanying drawings and embodiments.

[0051] As shown in FIG. 1 and FIG. 19, an integrated variable-axis free-bend forming apparatus for tubes proposed by the disclosure includes: a base movement module 1, a precision adjustment module 2, a fixed guide module 3, and a bending processing module 4.

[0052] The base movement module 1 is configured to adjust translational degrees of freedom of the apparatus along an X axis and a Y axis, providing the apparatus with motion freedom in X and Y directions.

[0053] The precision adjustment module 2 is fixedly connected to the base movement module 1. The precision adjustment module 2 is configured to switch processing state of the bending processing module 4. Specifically, by changing positions of rotary motors 29 in state switching modules 24 and driven shafts 37 in auxiliary adjustment modules 25, a bending die 46 can be switched among three states: follow-up, semi-active, and active, thereby adjusting the number of processing axes of the apparatus. The precision adjustment module 2 is connected in series to the base movement module 1. By changing the positions of the two rotary motors 29 and the two driven shafts 37 in the precision adjustment module 2, the number of processing axes of the apparatus can be switched.

[0054] The fixed guide module 3 is configured to guide a straight tube blank 5. The fixed guide module 3 is located at a rear side of the bending processing module 4. This module forms a physical constraint with a guide fin 47 at the rear side of the bending processing module 4 to control the spatial attitude of the bending die 46 in the follow-up state and the semi-active state. The fixed guide module 3 serves firstly to adjust the attitude (i.e., posture) of the bending die 46 (i.e., rotation about a RX axis and a RY axis) in the follow-up and semi-active states, and secondly to guide the straight tube blank 5, preventing the unprocessed section of the straight tube blank 5 (i.e., the section at the rear side of the bending processing module, in contact with the fixed guide module) from becoming unstable or deforming.

[0055] The bending processing module 4 is installed in a center of the precision adjustment module 2. The bending processing module 4 is configured to process the straight tube blank 5 to complete the free-bend forming of the straight tube blank 5. The bending processing module 4 directly contacts the straight tube blank 5 to apply the forming load required for tube bending.

[0056] As shown in FIG. 2, the base movement module 1 includes an X-axis linear translation assembly and a Y-axis linear translation assembly. The Y-axis linear translation assembly is fixedly connected to the X-axis linear translation assembly, and the Y-axis linear translation assembly is fixedly connected to the precision adjustment module 2.

[0057] The X-axis linear translation assembly includes an X-axis motor 9, first sliders (also referred to as sliding blocks) 12, first slide rails 13, a horizontal support plate 14, a first screw nut, and a ball screw 15. The first slide rails 13 and the X-axis motor 9 are fixedly installed via bolts in a horizontally arranged manner within the horizontal support plate 14. Four first sliders 12 are slidably installed on the first slide rails 13. The ball screw 15 is installed within the horizontal support plate 14 via a bearing seat. The first screw nut is sleeved on the ball screw 15. The axial direction of the ball screw 15 is defined as the X axis, and the track direction of the first slide rails 13 is parallel to the axial direction of the ball screw 15. An end of the ball screw 15 is coaxially connected to the output shaft of the X-axis motor 9. A vertical primary support plate 16 of the Y-axis linear translation assembly is fixedly connected to the first sliders 12 and a first nut fixing seat. Rotation of the X-axis motor 9 drives the ball screw 15 to rotate, thereby driving the Y-axis linear translation assembly to move along the X axis.

[0058] The Y-axis linear translation assembly includes a Y-axis motor 6, a motor installation seat 7, a vertical secondary support plate 8, a support beam 10, a motor installation plate 11, the vertical primary support plate 16, a tail end bearing seat 17, a nut fixing seat 18, a Y-axis screw, Y-axis guide rails, a screw nut 19, a front end bearing seat 20, and a coupling 22. The Y-axis motor 6 is fixedly installed within the vertical primary support plate 16 via the motor installation seat 7. Two ends of the Y-axis screw are installed within the vertical primary support plate 16 via the tail end bearing seat 17 and the front end bearing seat 20. The vertical primary support plate 16 is provided with vertically arranged Y-axis guide rails and the Y-axis screw. Four Y-axis sliders are slidably installed on the Y-axis guide rails. The screw nut 19 is sleeved on the Y-axis screw. The vertical secondary support plate 8 is fixedly connected to the screw nut 19 via the nut fixing seat 18. The axial direction of the Y-axis screw is defined as the Y axis, and the track direction of the Y-axis guide rails is parallel to the axial direction of the Y-axis screw. The output shaft of the Y-axis motor 6 is coaxially connected to the Y-axis screw via a first key 21 and the coupling 22. The support beam 10 is fixedly connected to the vertical secondary support plate 8. The precision adjustment module 2 is fixedly connected to the vertical secondary support plate 8 and the support beam 10. Rotation of the Y-axis motor 6 drives the Y-axis screw to rotate, causing the screw nut 19 to move along the Y axis, thereby driving the precision adjustment module 2 to move along the Y axis.

[0059] As shown in FIG. 3, FIG. 6, and FIG. 14, the precision adjustment module 2 includes a main body installation module 23, two state switching modules 24, and two auxiliary adjustment modules 25. The main body installation module 23 includes a main body support plate 39, a cross roller bearing 40, a bending die installation seat 41, and a drive shaft 42. The main body support plate 39 of the main body installation module 23 is fixedly connected to the vertical secondary support plate 8 of the base movement module 1. A bending die support member 45 of the bending processing module 4 is disposed within the bending die installation seat 41. The bending die support member 45 is connected to the bending die installation seat 41 via the state switching modules 24 and the auxiliary adjustment modules 25. Four side surfaces of the bending die installation seat 41 are sequentially defined as an RX side surface, an RY side surface, an A side surface, and a B side surface. The RY side surface of the bending die installation seat 41 is installed on the main body support plate 39 via the cross roller bearing 40. The inner and outer rings of the cross roller bearing 40 can rotate relative to each other. The outer ring of the cross roller bearing 40 is connected to the main body support plate 39, and the inner ring of the cross roller bearing 40 is connected to the RY side surface of the bending die installation seat 41, thereby providing the bending die installation seat 41 with a rotational degree of freedom relative to the main body support plate 39. The two state switching modules 24 are respectively defined as an RX-axis state switching module and an RY-axis state switching module. The output shaft of the RX-axis state switching module is parallel to the X axis of the base movement module 1. The output shaft of the RY-axis state switching module is parallel to the Y axis of the base movement module 1. The RX-axis state switching module is installed at the RX side surface of the bending die installation seat 41. The RY-axis state switching module is installed at the RY side surface of the bending die installation seat 41. The two auxiliary adjustment modules 25 are respectively disposed at the A side surface and the B side surface of the bending die installation seat 41, and the driven shaft 37 of each auxiliary adjustment module 25 is connected to a guide block 48 or the bending die support member 45 of the bending processing module 4. Thrust bearings 43 are connected between the bending die installation seat 41 and the RX side of the bending die support member 45 and between their respective A side surfaces. The driven shaft of the auxiliary adjustment module 25 at the A side surface is connected to the bending die installation seat 41 via a flange bearing 44. The purpose of installing the thrust bearings 43 and the flange bearing 44 is to eliminate friction caused by relative rotation between different components. In this embodiment, the B side surface of the bending die installation seat 41 is open, and the auxiliary adjustment module 25 at the B side surface is directly connected to the bending processing module 4. The drive shaft 42 is further fixedly installed at the RY side surface of the bending die installation seat 41. The cross roller bearing 40, an RY side plate of the bending die installation seat 41, the drive shaft 42, and the bending processing module 4 are arranged sequentially in that order along the axial direction of the output shaft of the RY-axis state switching module (i.e., the output shaft of the rotary motor 29). The position where the output shaft of the RY-axis state switching module is fixed to the drive shaft 42 is defined as a position 3 (i.e., third position).

[0060] Each state switching module 24 includes a rotary motor 29, a rotary motor installation member 34, and two sets of axial position control assemblies. The rotary motor installation member 34 is installed on a corresponding side surface of the bending die installation seat 41 via the axial position control assemblies. The rotary motor 29 is fixedly installed in the rotary motor installation member 34. The axial position control assemblies are configured to adjust the axial displacement of the rotary motor 29, thereby switching the connection state of the output shaft of the rotary motor 29, i.e., switching the connection state of the output shaft of the rotary motor 29 via a third key 51 with different components (such as the guide block 48, the bending die support member 45, or the drive shaft 42), thus switching the processing state of the bending processing module 4. The two axial position control assemblies of the state switching module 24 have two arrangement modes: diagonally opposite arrangement and same-side parallel arrangement. The diagonally opposite arrangement means gear motors 35 of the two axial position control assemblies are located on opposite edges of the rotary motor installation member 34. The same-side parallel arrangement means the gear motors 35 of the two axial position control assemblies are located on the same edge of the rotary motor installation member 34. The state switching module 24 on the RX-axis side of the main body installation module 23 adopts the diagonally opposite arrangement. The state switching module 24 on the RY-axis side of the main body installation module 23 adopts the same-side parallel arrangement, meaning the gear motors 35 of the two axial position control assemblies are located on the same edge of the rotary motor installation member 34, and the line connecting the two drive gears 31 is parallel to that edge of the rotary motor installation member 34.

[0061] As shown in FIG. 4, each axial position control assembly includes a slide rail installation member 26, a second slide rail 27, a second slider 28, a second key 30, a drive gear 31, a linear rack 32, a gear motor installation member 36, a rack installation member 33, and a gear motor 35. The linear rack 32 is fixedly connected to the bending die installation seat 41 via the rack installation member 33. The gear motor 35 is fixedly connected to the rotary motor installation member 34 via the gear motor installation member 36. The output shaft of the gear motor 35 is coaxially fixed to the drive gear 31 via the second key 30. The drive gear 31 meshes with the linear rack 32 to form a gear-rack pair. The second slide rail 27 is fixedly connected to the bending die installation seat 41 via the slide rail installation member 26. The second slider 28 is slidably installed on the second slide rail 27. The arrangement direction of the linear rack 32 is parallel to the sliding direction of the second slider 28. The axial direction of the output shaft of the gear motor 35 is perpendicular to the axial direction of the output shaft of the rotary motor 29. The gear motor 35 drives the rotary motor installation member 34 to slide along the axial direction of the output shaft of the rotary motor 29 via the gear-rack pair, while the second slider 28 slides along the axial direction of the output shaft of the rotary motor 29 within the second slide rail 27. The second slide rail 27 and the second slider 28 are used to ensure the stability of the motion of the rotary motor installation member 34.

[0062] As shown in FIG. 6 and FIG. 7, in the RY-axis state switching module, the rotary motor installation member 34 is further provided with two limit posts 54. When the output shaft of the rotary motor 29 in the RY-axis state switching module is fixedly connected to the bending die support member 45 or the guide block 48 in the bending processing module 4 via the third key 51, the two limit posts 54 are engaged in RY limit holes on the drive shaft 42. This is used to restrict the rotational degree of freedom of the bending die installation seat 41 about the RY axis, preventing possible rotation of the bending die installation seat 41 about the RY axis when the bending die 46 is in the following or semi-active state.

[0063] As shown in FIG. 5, each auxiliary adjustment module 25 includes cylinders 38 and the driven shaft 37. The output shafts of two cylinders 38, arranged symmetrically about the axis of the driven shaft 37, are fixedly connected to the driven shaft 37. The driven shaft 37 is controlled to connect with the bending die support member 45 or the guide block 48 of the bending processing module 4 via the extension and retraction of the cylinders 38. The positions of the driven shafts 37 on the A side and the B side are determined by the number of axes during processing.

[0064] As shown in FIG. 8, FIG. 9, FIG. 10, and FIG. 11, the bending processing module 4 includes a bending die 46, a bending die support member 45, guide blocks 48, limit blocks 50, and compression springs 49. The bending die support member 45 is disposed within the bending die installation seat 41 of the precision adjustment module 2. The bending die 46 is rotatably installed within the bending die support member 45. The bending die 46 and the bending die support member 45 are fitted together via a spherical surface. Two end portions of the bending die 46 are provided with inward recesses (i.e., the inward inclined surfaces shown in FIG. 11), and a middle portion of the bending die 46 is provided with an axial hole. The straight tube blank 5 is disposed within the axial hole of the middle portion of the bending die 46. Because the two end portions of the bending die 46 are provided with the inward recesses, the shape of the inner side wall of this hole is arc-shaped. The inner side wall of the axial hole of the middle portion of the bending die 46 is arc-shaped and serves as an action surface for the straight tube blank 5. The front end of the straight tube blank 5 is disposed within the axial hole of the middle portion of the bending die 46 and contacts the action surface. Axial guide grooves are provided at the RX side surface and the RY side surface of the bending die 46. Each guide block 48 is installed in the corresponding guide groove. The structure of the guide block 48 is as shown in FIG. 13. The profile shape of the guide groove along the axial direction is arc-shaped. The guide blocks 48 in the guide grooves are used to connect to the output shafts of the two state switching modules 24 and the driven shafts 37 of the two auxiliary adjustment modules 25, respectively. An end of each guide groove is open. The limit block 50 is installed at the end surface of the bending die 46 at the open end of each guide groove (i.e., its input end portion), used for limiting the guide block 48 and the compression spring 49. The structure of the limit block 50 is as shown in FIG. 12. The compression springs 49 are installed in the guide grooves at two ends of the guide blocks 48 at the RX side surface and the RY side surface, respectively, used to prevent the guide blocks 48 from moving when not subjected to force. The RX side and the RY side of the bending die support member 45 are provided with keyway holes. The A side and the B side of the bending die support member 45 are provided with through holes. The guide blocks 48 are provided with keyway holes. Counterbores are provided at the A side surface and the B side surface of the bending die 46, respectively, for embedding the driven shafts 37 of the auxiliary adjustment modules 25. The output shaft of the state switching module 24 and/or the driven shaft 37 of the auxiliary adjustment module 25 cooperates with the corresponding hole of the bending die support member 45, causing the output shaft of the state switching module 24 and the driven shaft 37 to cooperate with the bending die support member 45. The position where the output shaft of the state switching module 24 and/or the driven shaft 37 of the auxiliary adjustment module 25 cooperates with the bending die support member 45 is defined as a position 1 (i.e., first position). Or the output shaft of the state switching module 24 and/or the driven shaft 37 of the auxiliary adjustment module 25 cooperates with the bending die 46, the output shaft of the state switching module 24 cooperates with the guide block 48 of the bending die 46, the driven shaft 37 of the auxiliary adjustment module 25 cooperates with the counterbore on the side surface of the bending die 46, the position where the output shaft and/or the driven shaft 37 cooperates with the bending die 46 is defined as a position 2 (i.e., second position), and the output shaft of the RY-axis state switching module only cooperates with the driving shaft 42, and this position is defined as the position 3 (i.e., third position). The output shaft of the RY-axis state switching module can be set at the first position, the second position, or the third position, meaning the key on the output shaft only forms a cooperative relationship with one keyway. The output shaft of the RX-axis state switching module can be set at the first position or the second position.

[0065] When the bending die 46 is in the follow-up state and the semi-active state, the bending processing module 4 further includes guide fins 47. Multiple guide fins 47 are fixedly installed at the input end portion of the bending die 46 at intervals along the circumference via the limit blocks 50. The output end portion of a guide mechanism 52 of the fixed guide module 3 is disposed within the guide fins 47. The guide fins 47 and the output end of the guide mechanism 52 remain in contact during motion. The output end portion (i.e., the front end) of the guide mechanism 52 has an arc surface structure, used for physical contact with the guide fins 47 to control the spatial attitude of the bending die 46 in the follow-up state and the semi-active state. The guide mechanism 52 is installed on the guide mechanism fixing member 53 via six threaded holes and bolts at its rear side. During the tube bending process, the guide mechanism 52 remains stationary. When the bending die 46 is in the follow-up state, four guide fins are required. When the bending die 46 is in the semi-active state, two guide fins are required. When the bending die 46 is in the active state, no guide fins 47 are needed, i.e., the guide fins 47 are freely detachable. The bending die 46 has three motion states: follow-up, semi-active, and active. In the follow-up state, the bending die 46 possesses relative rotational degrees of freedom about the RX, RY, and RZ directions provided by the spherical surface fit. These three degrees of freedom are passively controlled by the physical contact between the guide fins 47 and the guide mechanism 52 during processing. The X and Y directional degrees of freedom of the bending die 46 are actively controlled by the X-axis motor 9 and the Y-axis motor 6 of the base movement module 1. In the semi-active state, the RX (or RY) degree of freedom of the bending die 46 is actively controlled by the corresponding rotary motor 29 of the state switching module at RX (or RY) side, the RZ degree of freedom is restricted by the motor of the rotary motor 29, and the remaining RY (or RX) degree of freedom is still passively controlled by the guide fins 47. In the active state, the X, Y, RX, and RY degrees of freedom of the bending die 46 are all actively controlled, and the RZ degree of freedom is constrained.

[0066] During processing, the number of processing axes can be autonomously selected according to forming requirements, dynamically balancing the accuracy and stability of tube bending, and expanding the application scope of the apparatus.

[0067] As shown in FIG. 15, the fixed guide module 3 includes a guide mechanism 52 and a guide mechanism fixing member 53. The guide mechanism 52 is fixedly installed on the guide mechanism fixing member 53. The straight tube blank 5 is disposed in the middle of the guide mechanism fixing member 53 and the guide mechanism 52. The straight tube blank 5 passes through an end of the guide mechanism 52 and then enters the bending die 46 of the bending processing module 4.

[0068] The disclosure further proposes a processing method for free-bend forming of tubes. The processing method uses the aforementioned integrated variable-axis free-bend forming apparatus for tubes. The processing method is shown in FIG. 20. The processing method includes the following steps.

[0069] When performing three-axis processing of the straight tube blank 5, the guide fins 47 are installed in the apparatus, the guide mechanism 52 of the fixed guide module 3 closely contacts with the guide fins 47, the output shafts of both the RX-axis state switching module and the RY-axis state switching module and the driven shafts of the auxiliary adjustment modules 25 at the A side surface and the B side surface are controlled to be located at the first position, i.e., fixed to the corresponding side plates of the bending die support member 45, and the limit posts 54 engage with the RY limit holes on the drive shaft 42, as shown in FIG. 16. This places the bending die 46 in the follow-up state. The bending die 46 has relative rotational degrees of freedom about the RX, RY, and RZ directions relative to the bending die support member 45. During the bending forming process, the X-axis motor 9 and the Y-axis motor 6 of the base movement module 1 actively control the motion of the bending processing module 4 in the X and Y directions. The rotary motors 29 on the RX-axis side and the RY-axis side remain stationary. The constraints from the output shafts of the two rotary motors 29 and the two driven shafts 37 cause the bending die support member 45 to move together with the main body installation module 23 in the X and Y directions without rotation. The relative rotation of the bending die 46 is adaptively adjusted through the contact between the guide fins 47 and the guide mechanism 52 during processing, completing the three-axis processing of the straight tube blank 5.

[0070] When performing four-axis processing of the straight tube blank 5, the guide fins 47 are installed in the apparatus, the guide mechanism 52 of the fixed guide module 3 closely contacts with the guide fins 47, the output shaft of either the RX-axis state switching module or the RY-axis state switching module is controlled to be at the second position, i.e., the output shaft is fixed to the corresponding guide block 48 of the bending die 46, the output shaft of the RY-axis state switching module or the RX-axis state switching module is controlled to be at the first position, and the driven shafts of the auxiliary adjustment modules 25 at the A side surface and the B side surface are controlled to be at the first position. This places the bending die 46 in the semi-active state, completing the four-axis processing of the straight tube blank 5. The rotary motor 29 at the RX-axis side or the RY-axis side can be autonomously chosen to be at the second position. If the RY-axis side rotary motor 29 is at the second position and the RX-axis side rotary motor 29 is at the first position, then the rotational degree of freedom of the bending die 46 in the RY direction is controlled by the RY-axis side rotary motor 29, the rotational degree of freedom in the RZ direction is restricted by the output shaft of the RY-axis side rotary motor 29, and the line connecting the two remaining guide fins is parallel to the RY-B axis system. If the RX-axis side rotary motor 29 is at the second position and the RY-axis side rotary motor 29 is at the first position, then the rotational degree of freedom of the bending die 46 in the RX direction is controlled by the RX-axis side rotary motor 29, the rotational degree of freedom in the RZ direction is restricted by the output shaft of the RX-axis side rotary motor 29, and as shown in FIG. 17, the line connecting the two remaining guide fins 47 is parallel to the RX-A axis system. When the third key 51 on the output shaft of the RX-axis side rotary motor 29 cooperates with the keyway of the guide block 48, rotation of the motor shaft of the RX-axis side rotary motor 29 can drive the guide block 48 and the bending die 46 assembled with the guide block to rotate in the RX direction. Simultaneously, when the base movement module 1 controls the bending processing module 4 to move along the X direction, the contact force between the guide fins 47 and the guide mechanism 52 can drive the guide block 48, which is engaged with the third key 51 on the RX-axis side rotary motor 29, to slide within the guide groove to achieve passive motion of the bending die 46 in the RY direction. The presence of the compression springs 49 ensures that the guide block 48 only moves when subjected to the contact force between the guide fins 47 and the guide mechanism 52, thereby ensuring the determinism and stability of the overall motion of the apparatus.

[0071] When performing five-axis processing of the straight tube blank 5, the output shaft of the RX-axis state switching module is controlled to be at the first position, i.e., the output shaft cooperates with the bending die support member 45, the output shaft of the RY-axis state switching module is controlled to be at the third position, and the driven shafts of the auxiliary adjustment modules 25 at the A side surface and the B side surface are controlled to be at the second position. The limit posts 54 do not engage with the RY limit holes on the drive shaft 42, as shown in FIG. 18, the driven shafts 37 on the A side and the B side fix the bending die 46 and the bending die support member 45 together, preventing any relative motion between them. The RY-axis side rotary motor 29 controls the bending die installation seat 41 and the entire bending processing module 4 to rotate in the RY direction. The RX-axis side rotary motor 29 controls the entire bending processing module 4 to rotate in the RX direction. This places the bending die 46 in the active state, completing the five-axis processing of the straight tube blank 5.

[0072] Therefore, the bending die 46 being in the follow-up state, the semi-active state, and the active state respectively represents that the set of free-bend forming apparatus for tubes has three-axis, four-axis, and five-axis processing capabilities. Free-bend forming apparatuses with a lower number of axes have higher processing stability and reliability. Free-bend forming apparatuses with a higher number of axes can perform additional rotational compensation to improve the forming accuracy of bent tubes. This apparatus integrates multiple processing axis numbers, allowing autonomous selection of the number of processing axes according to forming requirements, which can improve the processing efficiency of bent tubes while expanding the application scope of the apparatus.

[0073] Finally, it should be explained that the above embodiments and explanations are only used to illustrate the technical schemes of the disclosure, but not to limit it. Those skilled in the art should understand that the technical schemes of the disclosure can be modified or replaced by equivalents, without departing from the spirit and scope of the technical schemes of the disclosure, which should be included in the scope of protection of the claims of the disclosure.