Pipe fitting free bending forming device and method with smooth machining track

Abstract

The invention discloses a pipe fitting free bending forming device and method with a smooth machining track. Comprising a motion control module, a bending machining module and a deviation compensation module, the bending machining module directly controls the local shaping deformation degree of a straight pipe blank, and the motion control module is used for providing translation of the bending machining module in the X-axis direction and rotation around the Z-axis; and the deviation compensation module is used for carrying out rebounding secondary compensation on the formed pipe section pushed out of the bending die. An overall kinematic chain is optimized to be Z-C-X-B, a C-axis motion module in the motion control module can control the bending die to directly achieve rotary motion with the offset of the bending die as the radius and the center of the bending die in the static state as the circle center, then a smooth machining track is generated, the machining stability of the geometrical characteristics of the spatial bent pipe is improved, and the machining efficiency of the spatial bent pipe is improved. And the risk of mutual interference of various molds in the machining process is reduced through cooperative use of the deviation compensation module and the compensation coefficient, and the application range of the device is effectively expanded.

Description

Technical Field

[0001] The present invention belongs to the field of free bending forming of metal pipes and relates to a device and method for free bending forming of pipes, and in particular to a device and method for free bending forming of pipes with smooth processing tracks. Background Art

[0002] The rapid development of high-end manufacturing has led to increasing demands for structural complexity and forming quality in metal pipe bends. Pipe free bending technology precisely controls the local plastic deformation of straight pipe blanks by dynamically adjusting the spatial position of the bending die during processing. This technology offers a high degree of processing flexibility and is particularly suitable for the continuous bending of complex three-dimensional pipes.

[0003] Currently, free-bending devices for pipe fittings have processing axes ranging from three, four, five, and six, and free-bending devices with different numbers of axes have different applicability ranges. However, these devices share a common problem: the processing trajectory of the bending die is discrete. Specifically, the process parameters of the bending die include offset, forming angle, and swing angular velocity. The swing angular velocity refers to the angular velocity of the bending die rotating around the center of the bending die in a stationary state, with the offset as the radius. Due to the device structure, traditional free-bending devices can only first sample a series of discrete points on an ideal smooth processing trajectory and then control the bending die to bend the pipe through linear motion between adjacent points. This discrete trajectory not only causes the offset and forming angle of the bending die to change frequently during processing, but also inevitably introduces motion errors, thereby reducing the forming quality of the three-dimensional pipe. In addition, due to structural constraints, traditional devices have limited springback compensation capabilities. For large-angle three-dimensional pipe bends with bending-torsion coupling characteristics, springback defects still have a significant impact on the forming accuracy.

[0004] Therefore, in order to further improve the free bending forming quality of spatial bends and meet the growing application needs of various industries for complex structure bends, it is urgent to develop a new type of pipe free bending forming device that can produce a smooth processing trajectory and implement additional rebound compensation. Summary of the Invention

[0005] To address the problems described in the background art, the present invention provides a device and method for free-bending pipes with a smooth machining trajectory. This device optimizes the structure of a conventional six-axis free-bending device by adjusting the original C-axis from front to rear, and optimizing the transmission chain from the original ZXYCBA to ZCXB. This not only produces a continuous and smooth machining trajectory, but also effectively reduces redundant motion axes, improving the device's structural compactness and operational stability. Furthermore, by adjusting the spatial position of the rollers in the deviation compensation module, highly flexible comprehensive compensation for the curvature and torsion of the formed pipe segment can be achieved, effectively improving the forming quality of spatial bending.

[0006] The technical solution adopted in the present invention is as follows:

[0007] 1. A free bending forming device for pipe fittings with smooth processing trajectory

[0008] The free bending forming device for pipe fittings includes a guide module, a motion control module, a bending processing module and a deviation compensation module; the guide module is connected to the motion control module, the motion control module is connected to the bending processing module, the guide module and the bending processing module are installed on both sides of the motion control module, and the bending processing module is connected to the deviation compensation module; the motion control module is used to adjust the spatial position of the bending processing module; the guide module is used to ensure the stability of the straight tube blank to be bent during the processing process; the bending processing module is used to control the local plastic deformation of the straight tube blank; the deviation compensation module is used to perform secondary compensation for the changes in the geometric characteristics of the formed tube section caused by springback.

[0009] The motion control module includes an integral mounting seat, a C-axis motion module and an X-axis motion module; the C-axis motion module is installed on the side of the integral mounting seat close to the bending processing module, and the X-axis motion module is installed on the side of the C-axis motion module close to the bending processing module. The guide module is installed in the integral mounting seat and the guide section of the guide module passes through the integral mounting seat, the C-axis motion module and the X-axis motion module in sequence and is then arranged near the bending processing module.

[0010] The C-axis motion module includes an outer gear ring, a turntable bearing, a driving gear, a C-axis motor and a first motor mounting seat; the outer gear ring is mounted on the side of the integral mounting seat close to the bending processing module through the turntable bearing, the X-axis motion module is fixedly connected to the end face of the outer ring of the turntable bearing close to the bending processing module, the C-axis motor is connected to the integral mounting seat through the first motor mounting seat, the output shaft of the C-axis motor is coaxially fixedly connected to the driving gear, and the driving gear is meshed with the outer gear ring to form a gear pair.

[0011] The X-axis motion module includes an X-axis motor, a second motor mounting seat, a first screw bearing seat, a screw nut, a ball screw, a second screw bearing seat, a first-level support plate, a first slide rail, a first slider and a first-level support plate; the first-level support plate is fixedly connected to the C-axis motion module, the X-axis motor is fixedly connected to the first-level support plate through the second motor mounting seat, the ball screw is installed on the side of the first-level support plate close to the bending processing module through the first screw bearing seat and the second screw bearing seat, the first slide rail is also installed on the side of the first-level support plate close to the bending processing module, the sliding direction of the first slide rail is parallel to the axial direction of the ball screw, the ball screw outer sleeve is provided with a screw nut, the first slider is slidably installed in the first slide rail, the screw nut and the first slider are both fixedly connected to the first-level support plate, the first-level support plate and the first-level support plate are parallel and spaced apart, and the bending processing module is fixedly connected to the side of the first-level support plate close to the bending processing module.

[0012] The guide module assembly includes a guide module, a guide module mounting seat, a guide module movable plate, a second slider and a second slide rail; the second slide rail is fixedly connected to the integral mounting seat, the second slider is slidably installed in the second slide rail, the guide module mounting seat is fixedly connected to the second slider through the guide module movable plate, and the guide module is installed in the guide module mounting seat.

[0013] The bending processing module includes a bending die support, a rotation support assembly, a bending die, a bending die base and a B-axis motor; the bending die base is fixedly connected to the X-axis motion module, a deviation compensation module is installed on the side of the bending die base, a bending die support is arranged in the bending die base, the B-axis motor is fixedly connected to the bending die base, the output shaft axial direction of the B-axis motor is arranged perpendicular to the axial direction of the guide module, the output shaft of the B-axis motor is fixedly connected to one side of the bending die support, the side surface of the bending die support opposite to the side surface where the output shaft of the B-axis motor is located is connected to the bending die base through the rotation support assembly, and the bending die is fixedly installed in the bending die support; the B-axis motor drives the bending die support and the bending die to rotate in the bending die base.

[0014] The deviation compensation module includes a primary rotation module, a secondary rotation module, a first rotating motor, a roller support module, a linear motion module, a second secondary support plate and a second primary support plate; the primary rotation module is fixedly connected to the bending processing module, the primary rotation module is connected to the secondary rotation module through the second primary support plate, the secondary rotation module is connected to the linear motion module through the second secondary support plate, the first rotating motor is connected to the linear motion module, and the rotor end of the first rotating motor is connected to the roller support module.

[0015] The rotating support assembly includes a first support shaft, a first thrust bearing and a flange double bearing seat; one end of the first support shaft is connected to the bending mold base, and a flange double bearing seat is installed on the side of the bending mold support opposite to the side where the output shaft of the B-axis motor is located, and the other end of the first support shaft is connected to the flange double bearing seat through the first thrust bearing.

[0016] The first-stage rotating module includes a second support shaft, a third motor mounting seat, a third thrust bearing, a motor transmission member and a second rotating motor; the second rotating motor is fixedly connected to the third motor mounting seat, the motor transmission member is arranged in the third motor mounting seat, the output shaft of the second rotating motor is coaxially fixedly connected to one end of the motor transmission member, one end of the active second-level support plate is fixedly connected to the motor transmission member, the output shaft outer sleeve of the second rotating motor between the third motor mounting seat and the end of the active second-level support plate is provided with a corresponding third thrust bearing, and one end of the second support shaft is connected to the third motor mounting seat; one end of the passive second-level support plate is fixedly connected to the other end of the second support shaft, and the second support shaft outer sleeve between the third motor mounting seat and the end of the passive second-level support plate is provided with a corresponding third thrust bearing.

[0017] The secondary rotation module includes a fourth thrust bearing, a third support shaft, a third rotating motor and a fifth thrust bearing; the output shaft of the third rotating motor sequentially passes through the other end of the active second-level support plate, the fifth thrust bearing and one end of the active second-level support plate and then extends into the interior of the second motor transmission member; the active second-level support plate is fixedly connected to the second motor transmission member; the third support shaft is coaxially arranged with the output shaft of the third rotating motor, the other end of the passive second-level support plate is fixedly connected to one end of the third support shaft, and the other end of the third support shaft sequentially passes through the fourth thrust bearing and the passive second-level support plate.

[0018] The roller support module includes a roller support seat, a flange bearing, a roller shaft, a roller and a third retaining spring; the roller support seat is fixedly connected to the rotor end of the first rotating motor, the roller shaft is installed in the roller support seat through the flange bearing and the third retaining spring, and the roller is provided on the outer sleeve of the roller shaft.

[0019] 2. A method for free bending of pipe fittings

[0020] The forming method adopts the free bending forming device for pipe fittings with smooth processing trajectory, and the forming method includes the following steps:

[0021] Step 1: Calculate the processing parameters of the bending die corresponding to each point based on the base circle radius R and pitch P of each point on the axis of the target space bend; then calculate the processing time required for the target space bend based on the total length of the target space bend and the feed speed; and generate a bending die processing parameter sequence based on the processing parameters of the bending die at each point and the processing time required for the target space bend;

[0022] Step 2: Control the X-axis motion module, B-axis motor, C-axis motion module, and deviation compensation module in the tube free bending forming device according to the processing parameter sequence of the bending die to achieve bending forming of the straight tube blank.

[0023] In step 1, the base circle radius R and the pitch P of any point on the axis of the target space bend satisfy the following formula:

[0024]

[0025] Among them, t is the curve parameter representing any point on the axis of the target space bend, κ(t) is the curvature of any point, and τ(t) is the torsion of any point;

[0026] The processing parameters of the bending die include the offset U, the forming angle α, and the swing angular velocity ω. The processing parameters of any point on the axis of the target space bend satisfy the following formula:

[0027] U(t)=R(t)-R(t)cos(α(t))

[0028]

[0029] Among them, U(t) is the offset of any point, α(t) is the forming angle of any point, ω(t) is the swing angular velocity of any point, A is the projection of the distance from the front end of the guide die to the center of the bending die on the central axis of the guide die, v is the feed speed of the boosting mechanism, k1 and k2 are the compensation coefficients of curvature and torsion, respectively.

[0030] The step 2 is specifically as follows:

[0031] Step 2.1: Control the X-axis motion module, B-axis motor, and C-axis motion module in the tube free bending forming device so that the bending die changes linearly from a static state to a stable processing state;

[0032] Step 2.2: Control the X-axis motion module, B-axis motor, and C-axis motion module in the tube free bending forming device according to the processing parameter sequence, and simultaneously control the deviation compensation module to perform secondary compensation on the geometric features of the formed tube segment until the processing is completed;

[0033] Step 2.3: Control the bending die to linearly change from a stable processing state to a static state.

[0034] The beneficial effects of the present invention are as follows:

[0035] (1) The present invention does not require sampling of discrete points of the trajectory and can directly generate a smooth bending die processing trajectory, ensuring the stability of the bending die offset and forming angle as well as the continuity of the movement speed during the processing, thereby improving the stability of the geometric features during the free bending forming process of the spatial bend tube.

[0036] (2) The deviation compensation module introduced in the present invention enables designers to adopt smaller compensation coefficients k1 and k2 when calculating the bending die process parameters, and to perform additional springback compensation by adjusting the position of the deviation compensation module, which effectively reduces the risk of interference between the bending die and the guide die. This not only improves the processing capability of the free bending device, but also significantly expands the scope of application of the device. In addition, the secondary springback compensation based on the deviation compensation module is more intuitive and convenient than the primary compensation.

[0037] (3) The present invention eliminates redundant motion axes while retaining complete processing capabilities, making the structural layout of the entire device more compact, reducing the C-axis load, reducing costs, and improving the overall operating stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0039] Figure 2 It is a side sectional view of the present invention.

[0040] Figure 3 This is a structural diagram of the motion control module.

[0041] Figure 4 Schematic diagram of the structure of the C-axis motion module, where (a) is the schematic diagram of the structure of the C-axis motion module Figure 1 , (b) is the structural diagram of the C-axis motion module Figure 2 .

[0042] Figure 5 This is an exploded view of the X-axis motion module.

[0043] Figure 6 Exploded view of the guide module.

[0044] Figure 7 Schematic diagram of the bending processing module Figure 1 , where (a) is an exploded view of the bending processing module, (b) is a side view of the bending die support, and (c) is a top view of the bending die support.

[0045] Figure 8 This is a structural diagram of the deviation compensation module.

[0046] Figure 9 Schematic diagram of the bending processing module Figure 2 , where (a) is the exploded view of the first-level transmission module, (b) is the exploded view of the second-level transmission module, and (c) is the exploded view of the roller support module.

[0047] Figure 10 This is a working diagram of the deviation compensation module.

[0048] Figure 11 Schematic diagram of the processing process of the device of the present invention.

[0049] Figure 12 Schematic diagram of a traditional six-axis free bending forming device for pipes that can only produce discrete processing trajectories.

[0050] Figure 13 Schematic diagram of the processing parameters used in the present invention.

[0051] Figure 14 Schematic diagram of the smooth processing trajectory and discrete processing trajectory of the bending die.

[0052] In the figure: 1. Deviation compensation module, 2. Motion control module, 3. Bending processing module, 4. Straight tube blank, 5. Integral mounting seat, 6. C-axis motion module, 7. X-axis motion module, 8. Guide module, 9. Outer gear ring, 10. Turntable bearing, 11. Driving gear, 12. C-axis motor, 13. First motor mounting seat, 14. Support beam, 15. X-axis motor, 16. Second motor mounting seat, 17. First screw bearing seat, 18. Screw nut, 19. Ball screw, 20. Second screw bearing seat, 21. First and second support plate, 22. First slide rail, 23. First slider, 24. First and second support plates, 25. Guide die, 26. Guide die mounting seat, 27. Guide die moving plate, 28. Second slider, 29. Second slide rail, 30. Bending die support, 31. First support shaft, 32. A thrust bearing, 33. Flange double bearing seat, 34. Bending mold, 35. Bending mold base, 36. Second thrust bearing, 37. B-axis motor, 38. First-level rotation module, 39. Second-level rotation module, 40. Connecting rod, 41. First rotating motor, 42. Roller support module, 43. Linear motion module, 44. Second-level support plate, 45. Second-level support plate, 46. Second support shaft, 47. Third motor mounting seat, 48. Third thrust bearing, 49. First retaining spring, 50. Motor transmission part, 51. Second rotating motor, 52. Second retaining spring, 53. Fourth thrust bearing, 54. Third support shaft, 55. Third rotating motor, 56. Fifth thrust bearing, 57. Roller support seat, 58. Flange bearing, 59. Roller shaft, 60. Roller, 61. Third retaining spring, 62. Boosting mechanism. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation examples.

[0054] like Figure 1 and Figure 2 As shown, the present invention proposes a free-bending device for pipe fittings with a smooth machining path, comprising a guide module 8, a motion control module 2, a bending module 3, and a deviation compensation module 1. One side of the guide module 8 is connected to the motion control module 2, which is in turn connected to the bending module 3. The guide module 8 and the bending module 3 are mounted on either side of the motion control module 2. The bending module 3 is connected to the deviation compensation module 1, with the actuator end of the deviation compensation module 1 and the motion control module 2 positioned on either side of the bending module 3. The guide module 8 houses a straight tube 4, with the guide section of the guide module 8 passing through the motion control module 2 and positioned adjacent to the bending module 3. The motion control module 2 is used to adjust the spatial position of the bending module 3. The guide module 8 ensures the stability of the section of the straight tube 4 to be bent during machining. The bending module 3 controls the local plastic deformation of the straight tube 4. The deviation compensation module 1 provides secondary compensation for changes in the geometric characteristics of the formed tube section caused by springback. In actual processing, a boosting mechanism 62 is placed on the other side of the guide module 8. The boosting mechanism 62 contacts or is fixed to one end of the straight tube blank 4. The other end of the straight tube blank 4 passes through the guide module 8 and the motion control module 2 and is set in the bending die support 30 of the bending processing module 3.

[0055] like Figure 3 As shown, the motion control module 2 includes an integral mounting seat 5, a C-axis motion module 6 and an X-axis motion module 7; the integral mounting seat 5 is installed on an external frame, and the C-axis motion module 6 is installed on the side of the integral mounting seat 5 close to the bending processing module 3, and the X-axis motion module 7 is installed on the side of the C-axis motion module 6 close to the bending processing module 3. The second slide rail 29, the guide die mounting seat 26, the guide die moving plate 27 and the second slider 28 of the guide module 8 are all installed in the integral mounting seat 5 and the guide section of the guide module 8 passes through the integral mounting seat 5, the C-axis motion module 6 and the X-axis motion module 7 in sequence and is arranged near the bending die support 30 of the bending processing module 3. The straight tube blank 4 extending from the guide module 8 will extend into the bending die support 30 for bending processing.

[0056] like Figure 4 (a) and Figure 4As shown in (b), the C-axis motion module 6 includes a support beam 14, an outer gear ring 9, a turntable bearing 10, a driving gear 11, a C-axis motor 12 and a first motor mounting seat 13; the outer gear ring 9 is mounted on the side of the integral mounting seat 5 close to the bending processing module 3 through the turntable bearing 10, that is, the inner ring of the turntable bearing 10 is mounted on the integral mounting seat 5, and the outer ring and the outer gear ring 9 are nested together and remain relatively stationary. The first-level support plate 21 of the X-axis motion module 7 is fixedly connected to the end face of the outer ring of the turntable bearing 10 close to the bending processing module 3, and the C-axis motor 12 is connected to the integral mounting seat 5 through the first motor mounting seat 13 and the support beam 14. The two support beams 14 arranged side by side are used to improve the installation rigidity of the C-axis motor 12. The output shaft of the C-axis motor 12 is coaxially fixedly connected to the driving gear 11, and the driving gear 11 is meshed with the outer gear ring 9 to form a gear pair. The guide section of the guide module 8 is arranged inside the turntable bearing 10. The C-axis motor 12 drives the outer gear ring 9 and the X-axis motion module 7 mounted on the outer ring of the turntable bearing 10 to rotate around the Z-axis by controlling the rotation of the driving gear 11.

[0057] like Figure 5As shown, the X-axis motion module 7 includes an X-axis motor 15, a second motor mounting seat 16, a first screw bearing seat 17, a screw nut 18, a ball screw 19, a second screw bearing seat 20, a first-level support plate 21, a first slide rail 22, a first slider 23 and a first-level support plate 24; the first-level support plate 21 is fixedly connected to the outer ring end face of the turntable bearing 10 of the C-axis motion module 6, the X-axis motor 15 is fixedly connected to the first-level support plate 21 through the second motor mounting seat 16, and the ball screw 19 is installed on the side of the first-level support plate 21 close to the bending processing module 3 through the first screw bearing seat 17 and the second screw bearing seat 20. A first slide rail 22 is also installed on the side of the first-level support plate 21 near the bending module 3. The sliding direction of the first slide rail 22 is parallel to the axial direction of the ball screw 19. In the initial state, the axial direction of the ball screw 19 is located in the horizontal plane. The ball screw 19 is covered with a screw nut 18. The first slider 23 is slidably installed in the first slide rail 22. The screw nut 18 and all the first sliders 23 are fixedly connected to the first-level support plate 24. The first-level support plate 21 and the first-level support plates 24 are arranged parallel and spaced apart. The bending die base 35 of the bending module 3 is fixedly connected to the side of the first-level support plate 24 near the bending module 3. In this embodiment, the first slide rail 22 and the first slider 23 are provided in two pairs, respectively installed above and below the ball screw 19. The presence of the first slider 23 ensures the smooth movement of the first-level support plates 24. Guide holes are defined in the middle of the first and second support plates 21, 24. The guide segments of the guide module 8 are sequentially inserted through the guide holes of the first and second support plates 21, 24. The rotation of the motor shaft of the X-axis motor 15 drives the lead screw nut 18 to move parallel to the ball screw 19, thereby controlling the movement of the first and second support plates 24 and the bending module 3 mounted thereon in the X-axis direction.

[0058] like Figure 6 As shown, the guide die assembly 8 includes a guide die 25, a guide die mounting base 26, a guide die movable plate 27, a second slider 28, and a second slide rail 29. The two second slide rails 29 are fixedly connected to the integral mounting base 5. The two second slide rails 29 are parallel and spaced apart, and the sliding direction of each second slide rail 29 is parallel to the axial direction of the guide die 25. Each second slider 28 is slidably mounted in a corresponding second slide rail 29. The guide die mounting base 26 is fixedly connected to the second slider 28 via the guide die movable plate 27, and the guide die 25 is mounted in the guide die mounting base 26. In this way, the sliding freedom between the second slider 28 and the second slide rail 29 allows the guide die 25 to have a translational freedom in the Z-axis direction. Adjusting the position of the guide die 25 in the Z-axis direction can change the parameter A in the calculation formula for the forming angle of the bending die 34, thereby providing the device with more parameter selection space and enhancing the device's applicability.

[0059] like Figure 7 (a) Figure 7 (b) and Figure 7 As shown in (c), the bending processing module 3 includes a bending mold support 30, a rotation support assembly, a bending mold 34, a bending mold base 35, a second thrust bearing 36 and a B-axis motor 37; the bending mold base 35 is fixedly connected to the first and second support plates 24 of the X-axis motion module 7 near the side of the bending processing module 3, and the first-level rotation module 38 of the deviation compensation module 1 is installed on the side of the bending mold base 35. A mounting cavity is opened inside the bending mold base 35, and a bending mold support 30 is provided in the mounting cavity inside the bending mold base 35. The B-axis motor 37 is fixedly connected to the bending mold base 35, and the output shaft of the B-axis motor 37 is axially perpendicular to the axial direction of the guide module 8. The output shaft of the B-axis motor 37 is connected to a side surface of the bending mold support 30 through a key ( Figure 7 In order to avoid friction between the bending die base 35 and the bending die support 30, a second thrust bearing 36 is provided between the lower surface of the top of the bending die base 35 and the upper surface of the top of the bending die support 30. The output shaft of the B-axis motor 37 passes through the top of the bending die base 35 and the second thrust bearing 36 in sequence and is then provided on the top of the bending die support 30. In order to ensure the stability of the rotational movement of the bending die support 30, the side surface ( Figure 7 The bottom surface in the center) and the bending die base 35 are connected by a rotating support assembly, and the bending die 34 is fixedly installed in the bending die support 30; the B-axis motor 37 drives the bending die support 30 and the bending die 34 to rotate in the bending die base 35. The second thrust bearing 36 and the first thrust bearing 32 are to avoid friction between parts. The shaft structure at the upper end of the bending processing module 3 is B-axis motor 37-bending die base 35-second thrust bearing 36-bending die support 30, and the shaft structure at the lower end is first support shaft 31-bending die base 35-first thrust bearing 32-flange double bearing seat 33-bending die support 30. After the bending processing module 3 is assembled, the central axis of the B-axis motor 37 and the first support shaft 31 will pass through the center of the bending die 34, thereby ensuring that the center of the bending die 34 is located on the rotation center.

[0060] The rotating support assembly includes a first support shaft 31, a first thrust bearing 32 and a flange double bearing seat 33; one end of the first support shaft 31 is connected to the lower bottom surface of the bending mold base 35, and a flange double bearing seat 33 is installed on the side of the bending mold support 30 opposite to the side where the output shaft of the B-axis motor 37 is located. The other end of the first support shaft 31 is connected to the flange double bearing seat 33 through the first thrust bearing 32.

[0061] like Figure 8As shown, the deviation compensation module 1 includes a primary rotation module 38, a secondary rotation module 39, a connecting rod 40, a first rotary motor 41, a roller support module 42, a linear motion module 43, a second secondary support plate 44, and a second primary support plate 45. The third motor mounting base 47 of the primary rotation module 38 is fixedly connected to the bending die base 35 of the bending processing module 3. The primary rotation module 38 is connected to the second rotary module 39 via the second primary support plate 45. The second rotary module 39 is connected to the linear motion module 43 via the second secondary support plate 44. The two second secondary support plates 44 are connected by multiple connecting rods 40 to enhance the structural rigidity of the entire module and transmit motor torque. The connecting rod 40 is an aluminum column. The linear motion module 43 is a screw-slider assembly consisting of a motor, a lead screw, and a lead screw slider. The first rotary motor 41 is connected to the lead screw slider of the linear motion module 43, and the rotor end of the first rotary motor 41 is connected to the roller support base 57 of the roller support module 42. The primary rotation module 38 and the secondary rotation module 39 form a secondary adjustment module, which is used to adjust the distance between the roller support module 42 and the straight tube 4 in the axial direction of the straight tube 4. The linear motion module 43 is used to drive the first rotary motor 41 to move linearly in a direction perpendicular to the axial direction of the straight tube 4, thereby adjusting the distance between the roller support module 42 and the straight tube 4 in the direction perpendicular to the axial direction of the straight tube 4. The first rotary motor 41 is used to drive the rotation of the roller support module 42. The range of motion of the roller support module is limited to 90° clockwise and 90° counterclockwise. When the rotation angle is 0°, the axis of the roller 60 is parallel to the axis of the B-axis motor 37. The secondary adjustment module is used to ensure that the roller 60 is in contact with the formed tube section of the straight tube 4.

[0062] like Figure 9As shown in (a), the first-level rotating module 38 includes a second support shaft 46, a third motor mounting seat 47, a third thrust bearing 48, a first retaining spring 49, a motor transmission member 50 and a second rotating motor 51; the third motor mounting seat 47 is located at the center position of the left side of the bending mold base 35, the second rotating motor 51 is fixedly connected to the third motor mounting seat 47, the interior of the third motor mounting seat 47 is hollow, the motor transmission member 50 is arranged in the third motor mounting seat 47, the output shaft of the second rotating motor 51 is coaxially fixed with one end of the motor transmission member 50, one end of the active second-level support plate 45 is fixedly connected to the motor transmission member 50, and the output shaft of the second rotating motor 51 between the third motor mounting seat 47 and the end of the active second-level support plate 45 is provided with a corresponding third thrust bearing 48, which is used to prevent friction between the third motor mounting seat 47 and the active second-level support plate 45. One end of the second support shaft 46 is connected to the bottom of the third motor mounting seat 47; one end of the passive second-level support plate 45 is fixedly connected to the other end of the second support shaft 46, and a first retaining spring 49 is installed at the other end of the second support shaft 46 to limit the passive second-level support plate 45. A corresponding third thrust bearing 48 is provided on the outer sleeve of the second support shaft 46 between the third motor mounting seat 47 and the end of the passive second-level support plate 45 to prevent friction between the third motor mounting seat 47 and the passive second-level support plate 45. The shaft system structure of the active end of the first-level rotating module 38 is the second rotating motor 51-third motor mounting seat 47-third thrust bearing 48-active second-level support plate 45-motor transmission member 50, and the shaft system structure of the passive end is the second support shaft 46-third motor mounting seat 47-third thrust bearing 48-passive second-level support plate 45-first retaining spring 49.

[0063] like Figure 9As shown in (b), the secondary rotation module 39 includes a second retaining spring 52, a fourth thrust bearing 53, a third support shaft 54, a third rotary motor 55, and a fifth thrust bearing 56. The output shaft of the third rotary motor 55 sequentially passes through the other end of the active second-primary support plate 45, the fifth thrust bearing 56, and one end of the active second-secondary support plate 44 before extending into the interior of the second motor transmission member. The active second-secondary support plate 44 is fixedly connected to the second motor transmission member. The third rotary motor 55 drives the second motor transmission member to rotate, which in turn drives the active second-secondary support plate 44 to rotate. The third support shaft 54 ​​is coaxially arranged with the output shaft of the third rotary motor 55, and the upper end of the third support shaft 54 ​​contacts the base of the third rotary motor 55. The other end of the passive second-primary support plate 45 is fixedly connected to one end of the third support shaft 54. The other end of the third support shaft 54 ​​sequentially passes through the fourth thrust bearing 53, the passive second-secondary support plate 44, and the second retaining spring 52. The second retaining spring 52 is used to limit the passive second-secondary support plate 44. The shaft structure of the active end of the secondary rotation module 39 is the motor transmission part 50-the second secondary support plate 44-the fifth thrust bearing 56-the second primary support plate 45-the third rotating motor 55, and the shaft structure of the passive end is the second retaining spring 52-the second secondary support plate 44-the fourth thrust bearing 53-the third support shaft 54-the second primary support plate 45; the first retaining spring 49 and the second retaining spring 52 are used for axial limitation.

[0064] like Figure 9 As shown in (c), the roller support module 42 includes a roller support seat 57, a flange bearing 58, a roller shaft 59, a roller 60, and a third retaining spring 61. The roller support seat 57 is fixedly connected to the rotor end of the first rotating motor 41. The roller shaft 59 is mounted within the roller support seat 57 via the flange bearing 58 and the third retaining spring 61. The roller 60 is mounted on the outer surface of the roller shaft 59 and can roll freely on the roller shaft 59. The shaft system structure of the roller support module 42 is third retaining spring 61-flange bearing 58-roller support seat 57-roller 60-roller support seat 57-flange bearing 58-third retaining spring 61. The third retaining spring 61 is used to axially limit the roller shaft 59. The roller 60 is directly mounted on the roller shaft 59 and can roll freely. This ensures that the friction between the roller 60 and the formed pipe section is rolling friction, reducing damage to the bent pipe surface caused by secondary rebound compensation.

[0065] like Figure 10As shown, the contact between the roller 60 and the formed pipe section generates two components of force: F1 and F2. The direction of F1 points to the center of the base circle of the contact point between the roller 60 and the formed pipe section, and the direction of F2 points to the pitch direction of the contact point between the roller 60 and the formed pipe section. These two forces respectively perform secondary compensation for the curvature and torsion of the formed pipe section. The deflection angle of the first rotary motor 41 determines the magnitude of these two components of force. When the first rotary motor 41 does not deflect, the center axis of the roller 60 is aligned with the second rotary motor 51 and the third rotary motor 5 5, the central axis of the roller 60 only provides F1. When the first rotary motor 41 deflects 90°, the central axis of the roller 60 is perpendicular to the central axes of the second rotary motor 51 and the third rotary motor 55. At this time, the roller 60 only provides F2. During the free bending forming process of the pipe, the first rotary motor 41 will maintain a certain deflection angle to compensate for both curvature and torsion. The function of the primary rotary module 38, the secondary rotary module 39 and the linear motion module 43 is to control the spatial position of the roller 60 so that it contacts the formed pipe section.

[0066] like Figure 11-14 As shown, the present invention proposes a free bending forming method for pipe fittings, which adopts a free bending forming device for pipe fittings with a smooth processing trajectory. The forming method includes the following steps:

[0067] Step 1: Calculate the processing parameters of the bending die 34 corresponding to each point according to the base circle radius R and pitch P of each point on the axis of the target space bend; then calculate the processing time required for the target space bend according to the total length of the target space bend and the feed speed, and generate the processing parameter sequence of the bending die 34 according to the processing parameters of the bending die 34 at each point and the processing time required for the target space bend.

[0068] For a space bend with known curvature and torsion, the base circle radius R(t) and pitch P(t) at any point on the bend axis can be calculated using the following formula:

[0069]

[0070] Among them, t is the curve parameter of any point on the axis of the target space bend, κ(t) is the curvature of any point on the axis of the target space bend, and τ(t) is the torsion of any point on the axis of the target space bend.

[0071] The calculation formula for the total length L of the elbow is:

[0072]

[0073] Among them, θ is the central angle of the bend, t0 is the initial curve parameter, t1 is the terminal curve parameter, R′(t) is the derivative of the base circle radius R(t), and θ′(t) is the derivative of the pitch P(t).

[0074] The processing parameters of the bending die 34 include the offset U, the forming angle α, and the swing angular velocity ω. The processing parameters of any point on the axis of the target space bend satisfy the following formula:

[0075] U(t)=R(t)-R(t)cos(α(t))

[0076]

[0077] Among them, U(t) is the offset corresponding to any point, α(t) is the forming angle corresponding to any point, ω(t) is the swing angular velocity corresponding to any point, A is the projection of the distance from the front end of the guide die 25 to the center of the bending die 34 on the central axis of the guide die 25, v is the feed speed of the booster mechanism 62, which maintains a uniform speed during the processing, k1 and k2 are the compensation coefficients of curvature and torsion, respectively, and their values ​​are set according to actual needs.

[0078] Step 2: Control the X-axis motion module 7, B-axis motor 37, C-axis motion module 6, and deviation compensation module 1 in the tube free bending forming device according to the processing parameter sequence of the bending die 34 to achieve bending of the straight tube 4. During the tube bending process, the offset of the bending die 34 is controlled by the X-axis motion module 7, the forming angle is controlled by the B-axis motor 37, and the swing angular velocity is controlled by the C-axis motion module 6. Because the C-axis motion module 6 is positioned post-process in the present invention, the movement of the bending die 34 along the X-axis does not change the position of the C-axis motion module 6. When the bending die 34 reaches the specified offset U and forming angle α, the rotation of the outer ring of the turntable bearing 10 directly causes the bending die 34 to rotate about the offset as the radius and the center of the bending die 34 when it is in a stationary state, thereby producing a smooth arc-shaped processing trajectory.

[0079] In contrast, the traditional free bending device can only produce discrete processing trajectories. The six-axis free bending device is now explained in detail using the example of a six-axis free bending device. The motion chain of the six-axis free bending device is ZXYCBA. Because the C-axis is located in front of the X-axis and the Y-axis, the movement of the X-axis or the Y-axis will change the position of the C-axis. Under this condition, the rotation of the C-axis cannot realize the rotational motion of the bending mold, and can only be approximated by the coupled motion of the four axes X, Y, A, and B. Specifically, the device first samples a series of discrete points on the ideal processing trajectory, and then approximates the ideal processing trajectory through the linear motion between two adjacent discrete points. The resulting processing trajectory is discrete.

[0080] Step 2 is as follows:

[0081] Step 2.1: Control the X-axis motion module 7, B-axis motor 37 and C-axis motion module 6 in the tube free bending forming device so that the bending die 34 changes linearly from the static state U, α and ω are both 0 to the initial stable processing state. The initial stable processing state is the state corresponding to the first processing parameter in the processing parameter sequence; wherein the movement direction of the C-axis motion module 6 is counterclockwise.

[0082] Step 2.2: Control the X-axis motion module 7, B-axis motor 37, and C-axis motion module 6 in the tube free bending forming device according to the processing parameter sequence. At the same time, control the deviation compensation module 1 to perform secondary compensation on the geometric features of the formed tube segment until the processing is completed; the trajectory shape of the bending die 34 is determined by the offset and the forming angle.

[0083] The posture of the deviation compensation module 1 during the machining process is determined by the coordinates of the ideal axis of the target space bend. The geometric properties of any point on the ideal axis of the target space bend can be described by the Frenet frame, satisfying the following formula:

[0084]

[0085] in, is the derivative of the tangent vector a(t) at any point, is the derivative of the normal vector n(t) at any point, is the derivative of the binormal vector b(t) at any point, and dl is the unit arc length of the curve.

[0086] The coordinates of any point on the ideal axis can be obtained by integrating the Frenet frame:

[0087] r(t)=∫0 t a(t)dldt

[0088] Among them, r(t) is the three-dimensional coordinate of any point, which can be further expressed as P t (x t ,y t ,z t ), the origin O′ of the coordinate system is the center of the front end of the wire mold 25, the direction of movement of the X-axis motion module 7 is recorded as the x-axis, the direction of feed of the booster mechanism 62 is recorded as the z-axis, and the direction perpendicular to both the x-axis and the z-axis is set as the y-axis.

[0089] In step 2.2, the deviation compensation module 1 is controlled to perform secondary compensation of the geometric features of the formed pipe segment, specifically including:

[0090] First, all points on the ideal axis of the formed pipe section of the target space bend constitute the original space point set {P s}, take the original space point set {P sThe y coordinates and z coordinates of all points in the first plane point set {P i}, where P i The coordinates can be expressed as (y i ,z i ). Use the following formula to update the first plane point set {P i}, thereby obtaining a relative point set {p i ′}:

[0091]

[0092] Here, y0 and z0 are the y-coordinate and z-coordinate of the center of the primary rotating module 38 in a global coordinate system with the center O′ of the front end of the wire mold 25 as the origin.

[0093] Next, the geometric accessibility of the deviation compensation module 1 is determined, that is, {P s} contains how many points that the roller 60 can reach. This is determined from two aspects: First, it is determined whether the rotation of the primary rotating module 38 and the secondary rotating module 39 can control the roller 60 to approach the relative point set {p i Which points in the '} are named the first control plane point set {P p1}; Then, assign the first control point set {P p1} and convert them back into three dimensions and name them the first control space point set {P p2}, and then determine whether the motion of the linear motion module 43 can control the roller 60 to approach the first control space point set {P p2}, which points in the first control space point set {P p2 The points in the controllable linear motion module 43 constitute the second control space point set {P p3}.

[0094] Among them, the first control point set {P p1 The points in} satisfy the following conditions at the same time:

[0095] |l1-l2|≤d≤|l1+l2|

[0096]

[0097] Wherein, || represents the absolute value operation, l1 is the distance from the second rotary motor 51 to the third rotary motor 55, l2 is the distance from the third rotary motor 55 to the center axis of the roller 60, and the relative point concentration point (y i ′,z i The calculation formula of the distance d is θ1 is the rotation angle of the second rotary motor 51, and θ2 is the rotation angle of the third rotary motor 55. θ1 and θ2 are used to determine whether the rotation angle of the primary rotary module 38 and the secondary rotary module 39 corresponding to each point is within the allowable rotation angle range of the primary rotary module 38 and the secondary rotary module 39.

[0098] The second control space point set {P p3} point x i The following conditions are met:

[0099] x i ≤M

[0100] Wherein, M is the maximum allowable movement distance of the linear motion module 43 .

[0101] Finally, in the second control space point set {P p3}Select a point as the actual position of the roller 60 during the tube bending process. For the space bending tube with constantly changing base circle radius and pitch, continuously update the second control space point set {P p3}And generate the actual position of the roller 60 during the tube bending process, and realize the dynamic adjustment of the spatial posture of the roller 60.

[0102] The first rotary motor 41 has two functions: first, it further controls the position of the roller 60, ensuring contact with the formed pipe segment; second, it simultaneously provides forces to compensate for both curvature and torsion by adjusting the deflection angle of the roller 60. The deflection angle of the roller 60 directly determines the magnitude of both forces. During the pipe bending process, the operator can dynamically adjust the deflection angle of the roller 60 based on the degree of rebound of the curvature and torsion, thereby adapting to different working conditions.

[0103] Step 2.3: Control the bending die 34 to linearly change from the last stable processing state (ie, the last U, α and ω values ​​of the processing parameter sequence) to the static state U, α and ω are both 0.

[0104] The motion chain of the present invention is ZCXB, and the bending mold 34 with the offset U as the radius and the center O of the bending mold 34 when in a stationary state as the center of the circle can be directly realized by the C-axis motion module 6, and the resulting motion trajectory of the bending mold 34 is smooth and continuous.

[0105] The primary compensation of the free bending forming of spatial bends is the compensation coefficients k1 and k2 introduced when calculating the process parameters of the bending die 34. The secondary compensation is the direct control of the geometric shape of the formed pipe section by the deviation compensation module 1. These two rebound compensation methods are used in combination during the pipe bending forming process.

[0106] The contact between the roller 60 in the deviation compensation module 1 and the formed pipe segment generates two force components: F1 and F2. The directions of F1 and F2 are the center direction of the base circle of the contact point and the pitch direction, respectively, which are used to control the curvature and torsion of the formed pipe segment. The spatial position of the roller 60 is controlled by the primary rotation module 38, the secondary rotation module 39, the linear motion module 43 and the first rotary motor 41. The deflection angle of the first rotary motor 41 determines the size of F1 and F2. When the first rotary motor 41 does not deflect, that is, the roller 60 When the central axis of roller 60 is parallel to the central axis of the second rotary motor 51 or the third rotary motor 55, roller 60 will only generate F1. When the first rotary motor 41 is deflected 90°, that is, when the central axis of roller 60 is perpendicular to the central axis of the second rotary motor 51 or the third rotary motor 55, roller 60 will only generate F2. In order to enable the deviation compensation module 1 to simultaneously compensate for the curvature and torsion of the formed pipe section, the first rotary motor 41 will maintain a certain deflection angle during the pipe bending process, and the deflection angle will be adaptively adjusted according to the ideal geometric parameters of the pipe bend.

Claims

1. A free bending forming device for pipes with smooth processing trajectory, characterized in that: The invention comprises a guide module (8), a motion control module (2), a bending processing module (3) and a deviation compensation module (1); the guide module (8) is connected to the motion control module (2), the motion control module (2) is connected to the bending processing module (3), the guide module (8) and the bending processing module (3) are installed on both sides of the motion control module (2), and the bending processing module (3) is connected to the deviation compensation module (1); the motion control module (2) is used to adjust the spatial position of the bending processing module (3); the guide module (8) is used to ensure the stability of the straight tube blank (4) to be bent during the processing; the bending processing module (3) is used to control the local plastic deformation of the straight tube blank (4); and the deviation compensation module (1) is used to perform secondary compensation for the change in the geometric characteristics of the formed tube section caused by springback.

2. A free bending forming device for pipes with smooth processing trajectory according to claim 1, characterized in that: The motion control module (2) comprises an integral mounting seat (5), a C-axis motion module (6) and an X-axis motion module (7); the C-axis motion module (6) is mounted on the side of the integral mounting seat (5) close to the bending processing module (3); the X-axis motion module (7) is mounted on the side of the C-axis motion module (6) close to the bending processing module (3); the guide module (8) is mounted in the integral mounting seat (5), and the guide section of the guide module (8) passes through the integral mounting seat (5), the C-axis motion module (6) and the X-axis motion module (7) in sequence and is then arranged near the bending processing module (3).

3. The free bending forming device for pipes with smooth processing trajectory according to claim 2, characterized in that: The C-axis motion module (6) comprises an outer gear ring (9), a turntable bearing (10), a driving gear (11), a C-axis motor (12) and a first motor mounting seat (13); the outer gear ring (9) is mounted on the side of the integral mounting seat (5) close to the bending processing module (3) through the turntable bearing (10); the X-axis motion module (7) is fixedly connected to the end face of the outer ring of the turntable bearing (10) close to the bending processing module (3); the C-axis motor (12) is connected to the integral mounting seat (5) through the first motor mounting seat (13); the output shaft of the C-axis motor (12) is coaxially fixedly connected to the driving gear (11); and the driving gear (11) and the outer gear ring (9) are meshed to form a gear pair.

4. The free bending forming device for pipes with smooth processing trajectory according to claim 2, characterized in that: The X-axis motion module (7) comprises an X-axis motor (15), a second motor mounting seat (16), a first screw bearing seat (17), a screw nut (18), a ball screw (19), a second screw bearing seat (20), a first level support plate (21), a first slide rail (22), a first slider (23) and a first level support plate (24); the first level support plate (21) is fixedly connected to the C-axis motion module (6), the X-axis motor (15) is fixedly connected to the first level support plate (21) via the second motor mounting seat (16), and the ball screw (19) is mounted on the first level support plate (21) near the first level support plate through the first screw bearing seat (17) and the second screw bearing seat (20). A first slide rail (22) is installed on the side of the bending processing module (3) and the first primary support plate (21) near the side of the bending processing module (3). The sliding direction of the first slide rail (22) is parallel to the axial direction of the ball screw (19). The ball screw (19) is provided with a screw nut (18) on the outer shell. The first slider (23) is slidably installed in the first slide rail (22). The screw nut (18) and the first slider (23) are both fixedly connected to the first and second support plates (24). The first primary support plate (21) and the first and second support plates (24) are parallel and spaced apart. The bending processing module (3) is fixedly connected to the first and second support plates (24) near the side of the bending processing module (3).

5. The free bending forming device for pipes with smooth processing trajectory according to claim 1, characterized in that: The guide die assembly (8) comprises a guide die (25), a guide die mounting seat (26), a guide die moving plate (27), a second slider (28) and a second slide rail (29); the second slide rail (29) is fixedly connected to the integral mounting seat (5), the second slider (28) is slidably mounted in the second slide rail (29), the guide die mounting seat (26) is fixedly connected to the second slider (28) via the guide die moving plate (27), and the guide die (25) is mounted in the guide die mounting seat (26).

6. The free bending forming device for pipes with smooth processing trajectory according to claim 1, characterized in that: The bending processing module (3) comprises a bending die support (30), a rotation support assembly, a bending die (34), a bending die base (35) and a B-axis motor (37); the bending die base (35) is fixedly connected to the X-axis motion module (7); a deviation compensation module (1) is installed on the side of the bending die base (35); a bending die support (30) is provided in the bending die base (35); the B-axis motor (37) is fixedly connected to the bending die base (35); the output shaft of the B-axis motor (37) is axially The output shaft of the B-axis motor (37) is fixedly connected to one side of the bending die support (30) and is arranged perpendicular to the axial direction of the guide die group (8). The side of the bending die support (30) opposite to the side where the output shaft of the B-axis motor (37) is located is connected to the bending die base (35) via a rotating support assembly. The bending die (34) is fixedly installed in the bending die support (30); the B-axis motor (37) drives the bending die support (30) and the bending die (34) to rotate in the bending die base (35).

7. The free bending forming device for pipes with smooth processing trajectory according to claim 1, characterized in that: The deviation compensation module (1) comprises a primary rotation module (38), a secondary rotation module (39), a first rotation motor (41), a roller support module (42), a linear motion module (43), a second secondary support plate (44) and a second primary support plate (45); the primary rotation module (38) is fixedly connected to the bending processing module (3), the primary rotation module (38) is connected to the secondary rotation module (39) via the second primary support plate (45), the secondary rotation module (39) is connected to the linear motion module (43) via the second secondary support plate (44), the first rotation motor (41) is connected to the linear motion module (43), and the rotor end of the first rotation motor (41) is connected to the roller support module (42).

8. A method for free bending of pipe fittings, characterized in that: The forming method adopts the free bending forming device for pipe fittings with smooth processing trajectory as claimed in claim 1, and the forming method comprises the following steps: Step 1: Calculate the processing parameters of the bending die (34) corresponding to each point according to the base circle radius R and the pitch P of each point on the axis of the target space bend; then calculate the processing time required for the target space bend according to the total length of the target space bend and the feed speed, and generate the processing parameter sequence of the bending die (34) according to the processing parameters of the bending die (34) at each point and the processing time required for the target space bend; Step 2: Control the X-axis motion module (7), the B-axis motor (37), the C-axis motion module (6), and the deviation compensation module (1) in the tube free bending forming device according to the processing parameter sequence of the bending die (34) to achieve bending forming of the straight tube blank (4).

9. A pipe free bending forming method according to claim 8, characterized in that: In step 1, the base circle radius R and the pitch P of any point on the axis of the target space bend satisfy the following formula: Among them, t is the curve parameter representing any point on the axis of the target space bend, κ(t) is the curvature of any point, and τ(t) is the torsion of any point; The processing parameters of the bending die (34) include the offset U, the forming angle α and the swing angular velocity ω. The processing parameters of any point on the axis of the target space bend satisfy the following formula: U(t)=R(t)-R(t)cos(α(t)) Wherein, U(t) is the offset of any point, α(t) is the forming angle of any point, ω(t) is the swing angular velocity of any point, A is the projection of the distance from the front end of the guide die (25) to the center of the bending die (34) on the central axis of the guide die (25), v is the feed speed of the boosting mechanism (62), k1 and k2 are the compensation coefficients of curvature and torsion, respectively.

10. A pipe free bending forming method according to claim 8, characterized in that: The step 2 is specifically as follows: Step 2.1: Control the X-axis motion module (7), the B-axis motor (37), and the C-axis motion module (6) in the tube free bending forming device so that the bending die (34) changes linearly from a stationary state to a stable processing state; Step 2.2: Control the X-axis motion module (7), the B-axis motor (37), and the C-axis motion module (6) in the tube free bending forming device according to the processing parameter sequence, and simultaneously control the deviation compensation module (1) to perform secondary compensation of the geometric features of the formed tube segment until the processing is completed; Step 2.3: Control the bending die (34) to linearly change from a stable processing state to a stationary state.

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