Free bending forming apparatus and small radius bending forming method thereof

Abstract

The invention discloses a free bending forming device and its small radius bending forming method. The pushing mechanism pushes the guide pipe through the guide mechanism and the die hole of the bending die. A pressing wheel is installed on the front side of the bending die and can move with the bending die. The guide pipe changes the orientation of the die hole when bending freely. The part of the guide pipe extending from the die hole can be in contact with the pressing wheel, so that the guide pipe can be bent once between the guide mechanism and the bending die, and then the guide pipe can be further pressed or bent twice between the pressing wheel and the bending die. The space used for bending the pipe is increased, the rebound of the bent guide pipe is avoided, the bending angle with a bending radius less than twice the outer diameter of the guide pipe itself is avoided in a smaller space, and the qualified rate and the good product rate of the product are improved.

Description

Technical Field

[0001] This invention relates to the field of free bending pipes, and more particularly to a free bending forming apparatus and a small radius bending forming method. Background Technology

[0002] Three-dimensional free bending forming, as a significant technological innovation in the field of metal tube plastic forming, offers substantial advantages over traditional bending methods in forming components with multiple bending radii, variable bending radii, small bending radii, and continuous bending without straight sections. It holds significant application prospects in aerospace, nuclear energy equipment, and the automotive industry. Free bending forming of metal tubes is a flexible forming technology based on mold motion trajectory control, possessing considerable technological advantages in manufacturing components with complex three-dimensional axes and continuous bending without straight sections. It represents another breakthrough in recent technological advancements.

[0003] Patent document CN111545608B discloses a device and method for reducing the relative bending radius of a freely bending part, including a spherical bearing, a bending die, and a guide mechanism. The end of the bending die is spherically connected to the front end of the guide mechanism. The bending die and the guide mechanism are located on the same axis and can achieve vector deflection around the guide mechanism. The inner wall of the end of the bending die is a gently spherical surface, and the diameter of the spherical surface at the end of the bending die is slightly larger than the diameter of the spherical surface at the front end of the guide mechanism, ensuring that the spherical surface at the front end of the guide mechanism can move freely axially within the spherical surface at the end of the bending die to change the position of the guide mechanism and adjust the distance from the front end of the guide mechanism to the center of the bending die in real time. The guide mechanism is installed on a base using a threaded connection. This design is suitable for different cross-sectional shapes... Hollow components of different materials are used to adjust the position of the guide mechanism by changing the distance of the threaded movement, thereby adjusting the distance from the front end of the guide mechanism to the center of the bending die in real time and reducing the actual bending radius. A self-lubricating flexible mandrel is added inside the pipe. The self-lubricating flexible mandrel consists of a rod body and several ball heads. The ball heads are connected to each other and to the rod body by ball chains, which provide support to the inner wall of the pipe during the bending process. The exit section of the bending die is a conical structure that gradually increases in size or a "round top and square bottom" structure that gradually increases in size. The conical structure is suitable for round pipes, and the "round top and square bottom" structure is suitable for square pipes. A chamfer is added to the inner wall of the front end of the guide mechanism to reduce the pressure on the pipe during the bending process. The length of the guide mechanism is increased to 5A, where A is the distance from the front end of the guide mechanism to the center of the bending die.

[0004] However, the forming process with small bending radius has not been overcome in the field of free bending forming technology because small bending radius pipes are prone to instability and wrinkling failure during the bending forming process. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a free bending forming device for small-radius bending forming. A pressure roller is installed on the front side of the bending die, allowing the portion of the pipe extending from the die hole to abut against the pressure roller. This allows for pressure holding or secondary bending of the pipe between the pressure roller and the bending die, thereby increasing the space used for bending the pipe and realizing free bending forming processing with small bending radius, thus improving the quality of the bent pipe.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A free bending forming device includes a bending die and a guiding mechanism, and further includes a pressure roller for abutting the outside of a pipe protruding from the die hole of the bending die. A base is fixedly mounted on the bending die, and the pressure roller is rotatably mounted on the base.

[0008] Preferably, the pressure roller is mounted on the base in a manner that allows it to be close to or away from the axis of the die hole of the bending die.

[0009] Preferably, a slider that slides up and down is mounted on the base, and the slider is driven to move up and down by a servo motor, with the pressure roller mounted on the slider.

[0010] Preferably, a wedge block that slides left and right is installed on the base, and a slider is located above the wedge block. The slider has an inclined surface that matches the wedge block and the two slide together, so that when the wedge block moves left and right on the base, it can drive the slider to move up and down. The wedge block is driven to move left and right by a servo motor.

[0011] Preferably, the base has two first connecting parts protruding from it, and the wedge and the slider are both located between the two first connecting parts. The left and right ends of the slider are respectively slidably connected to the two first connecting parts up and down. The slider is located above the wedge, and the wedge slides left and right between the two first connecting parts.

[0012] Preferably, an annular groove is formed on the outer circumference of the pressure roller.

[0013] Preferably, the inner diameter of the annular groove is not less than the outer diameter of the pipe fitting.

[0014] Preferably, the longitudinal section of the annular groove and the longitudinal section of the mold hole are located in the same plane.

[0015] Preferably, the bending die is provided with a clearance groove; the bending die is rotatably mounted on the bracket and driven to rotate back and forth by a servo motor; a limiting rod is fixedly installed on the bracket, and the limiting rod is located above the rear of the bending die.

[0016] A small-radius bending forming method employs a free bending forming device as described above, wherein during the bending forming process of the pipe, the pressure roller always presses tightly against the outer side of the bent part of the pipe.

[0017] The beneficial effects of the technical solution of the present invention are as follows:

[0018] 1) Solved the problem of free bending forming of conduits with small bending radii in complex aerospace pipeline systems, and realized the bending forming capability with bending radius ≤ 2 times the conduit diameter on a three-dimensional flexible free bending forming device.

[0019] 2) During the pipe bending process, the pressure roller device can always press tightly against the outer side of the pipe bending part as the bending radius changes. This allows the pipe to be subjected to both the bending torque of the bending die and the outer pressure of the pressure roller device. Consequently, bending forces are applied to both parts of the pipe located on both sides of the bending die. This extends the length of the bent deformation part of the pipe from the area between the existing guide mechanism and the bending die to the area between the guide mechanism and the pressure roller. This makes the stress on the pipe more evenly distributed, resulting in better processing quality and higher processing accuracy when the free bending device performs free bending.

[0020] 3) Because the pressure roller always presses against the outer side of the already bent portion of the pipe, it counteracts the springback force of the bent portion, improving the dimensional accuracy of small-radius bent pipes. Preliminary tests show that with the addition of this small-radius bending forming pressure roller device, the three-dimensional flexible free bending forming device has the ability to bend pipes with small bending radii. The pass rate for free-bending small-radius pipes is higher, and the equipment can process pipes with more complex shapes. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the free bending forming device for small radius bending forming in this invention;

[0022] Figure 2 This is a schematic diagram of the structure of a free bending forming device for small-radius bending forming in its initial state;

[0023] Figure 3 This is a schematic diagram of a free bending forming device used for small-radius bending under small-radius bending conditions.

[0024] Figure 4 Schematic diagram of the connection structure between the pressure roller and the bending die Figure 1 ;

[0025] Figure 5 Schematic diagram of the connection structure between the pressure roller and the bending die Figure 2 ;

[0026] Figure 6 Schematic diagram of the connection structure between the pressure roller and the lifting mechanism Figure 1 ;

[0027] Figure 7 Schematic diagram of the connection structure between the pressure roller and the lifting mechanism Figure 2 ;

[0028] Figure 8 This is a schematic diagram illustrating the working principle of a free bending forming equipment in the existing technology.

[0029] Figure 9 This is a schematic diagram illustrating the working principle of the free bending forming equipment in this invention.

[0030] Figure 10 This is a schematic diagram of the bending die in this invention.

[0031] Reference numerals: 1. Bending die; 11. Die hole; 111. Front side wall; 112. Rear side wall; 12. Mounting plate; 13. Second servo motor; 14. Base plate; 15. Mounting seat; 16. Clearance groove; 151. Second connecting part; 2. Pressure roller; 21. Groove; 22. Slider; 221. Opening; 222. Sliding part; 23. Base; 231. First connecting part; 2311. Sliding groove; 2312. Pad; 232. Side baffle; 233. Front baffle; 24. First servo motor; 25. Wedge block; 26. Lead screw; 27. Rotating shaft; 28. Positioning block; 29. ​​Slide rail; 3. Pipe fitting; 4. Guide mechanism. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] The orientation described in the following embodiments is... Figure 1 The directions shown are for reference. Figure 1 The position of the bending die is taken as the base point, the position of the pressure roller is taken as the front, the position of the first servo motor is taken as the bottom, and the position of the second servo motor is taken as the left.

[0038] Example

[0039] A free bending forming device includes a bending die 1 and a guiding mechanism 4, and also includes a pressure roller 2 for abutting the outer side of the pipe protruding from the die hole 11 of the bending die 1. A base 23 is fixedly installed on the bending die 1, and the pressure roller 2 is rotatably installed on the base 23.

[0040] The method for bending pipe fittings to a small radius using the above-mentioned free bending forming device is as follows:

[0041] Step 1) as Figure 1 and Figure 2 As shown, the jacking mechanism can push the tube 3 through the discharge end 41 of the guide mechanism 4 and the die hole 11 of the bending die 1 in sequence and move it to the top of the pressure roller 2.

[0042] Step 2) as Figure 3As shown, the bending die 1 is moved and the orientation of the die hole 11 is changed. The pressure roller 2 moves radially along the die hole 1 and abuts against the part of the pipe 3 that extends out of the die hole 11. The pressure roller 2 is installed in front of the bending die 1, and the pressure roller 2 moves synchronously with the bending die 1 when the bending die 1 moves.

[0043] Step 3) Remove the bent pipe from the protruding direction of pipe 3.

[0044] like Figure 1-3 As shown, when the pipe 3 is bent to a small radius, the bending die 1 and the pressure roller 2 both move, which changes the original movement path of the pipe 3, causing the pipe 3 to deform.

[0045] like Figure 10 As shown, the die hole 11 of the bending die 1 includes a front sidewall 111 and a rear sidewall 112. The front sidewall 111 and the rear sidewall 112 both extend from the outside to the inside and intersect in the die hole 11. The cross section at the intersection of the front sidewall 111 and the rear sidewall 112 is the middle surface of the bending die. The cross section of the front sidewall 111 is an arc surface with a radius that gradually decreases from the outside to the inside, and the cross section of the rear sidewall 112 is an arc surface with a radius that gradually decreases from the outside to the inside. This makes the die hole 11 present a state of convexity in the middle.

[0046] like Figure 8 As shown, the process of small radius bending in the prior art free bending forming equipment is as follows: the bending die 1 rotates and changes the orientation of the die hole 11, causing the pipe to bend. At this time, the pipe 3 is subjected to a force from position A on the discharge end of the guide mechanism 4 and a force from position B on the rear side wall 112 of the die hole 11 located outside the bent part of the pipe, causing the pipe to deform and bend. Then, after the pipe bends, the outer wall of the inner side of the bent part of the pipe abuts against position C on the die hole 11 located on the front side wall 111 of the inner side of the bent part of the pipe, and is subjected to a force from position C on the front side wall 111. In this situation, because the pipe is in a free state during bending, the existing technology will have the following problems: Problem 1) Since the main deformation area and stress area of ​​the pipe are concentrated between position B and position A, the jacking mechanism continues to push, causing the pipe to generate relatively intense friction at position B and position C, resulting in instability in the pipe processing, wrinkles and uneven wall thickness on the pipe, leading to substandard pipe quality; Problem 2) Since the pipe will come into contact with the front side wall 111 at position C after bending, the deformed pipe will be subjected to an outward force. In addition, the springback characteristics of the pipe itself will cause the bent pipe to spring back further, making it impossible for the actual bending radius to reach the design value. This is especially obvious in small-radius free bending.

[0047] like Figure 9As shown, when processing small-radius bent pipes using the above-mentioned small-radius bending forming method for pipe fittings in this invention, the deformation process of the pipe fitting is as follows: when the bending die 1 changes orientation, the pipe fitting 3 deforms. At this time, the pipe fitting 3 is subjected to a force from position A on the discharge end of the guide mechanism 4 and a force from position B on the rear sidewall 112 of the part outside the bent portion of the pipe fitting on the die hole 11, causing the pipe fitting to deform and bend. Then, after the pipe fitting bends, the outer wall of the inner side of the bent portion of the pipe fitting abuts against position C on the front sidewall 111 of the inner side of the bent portion of the pipe fitting on the die hole 11, and is subjected to a force from position C on the front sidewall 111. In addition, the outer wall of the pipe fitting outside the bending die and located on the bent portion of the pipe fitting is also subjected to a force from position D on the pressure roller 2. The bending method of the present invention has the following advantages: Advantage 1) Since the pressure roller 2 is located on the front side of the bending die 1, the main stress area of ​​the pipe is increased from between position B and position A in the prior art to between position A, position B and position D. This increases the stress surface of the pipe, making the stress on the pipe more uniform during the small radius bending process; Advantage 2) Since position B and position C are located between position A and position D, both ends of the bending section of the pipe are restricted, thereby making the bending process of the pipe more stable and reducing the occurrence of wrinkles and wall thickness changes in the bending part of the pipe; Advantage 3) Since the pressure roller is located on the front side of the bending die, the force applied by the pressure roller at position D on the outside of the pipe can offset the rebound force of the pipe itself, and can also offset the outward pushing force from position C on the outer side 111 of the die hole 11, avoiding rebound after the pipe is formed, improving the processing quality and accuracy of pipe bending with a bending radius less than twice the diameter of the pipe itself, reducing production costs and reducing material waste.

[0048] To ensure a more stable contact between the pressure roller and the pipe fitting, in this embodiment, an annular groove 21 is formed on the outer circumference of the pressure roller 2. The groove 21 is located in front of the die hole 11. The cross-section of the groove is arc-shaped, and the inner diameter of the groove cross-section is not less than the outer diameter of the pipe fitting. The longitudinal section of the annular groove 21 and the longitudinal section of the die hole 11 are located in the same plane, and the axis of the die hole 11 is perpendicular to the axis of the pressure roller 2. This ensures a more secure contact between the pipe fitting and the pressure roller, and makes the bending process more stable.

[0049] In order to enable the roller to move synchronously with the bending mold 1, in this embodiment, as follows: Figure 2-7As shown, the pressure roller is mounted on the bending die via a lifting mechanism. The lifting mechanism includes a base 23, a slider 22, a wedge 25, a lead screw 26, and a first servo motor 24. The base 23 is fixedly connected to the bending die 1, with a portion of the base 23 located on the front side of the bending die 1. First connecting portions 231 protrude from both ends of the base 23. The slider 22 is located between two first connecting portions 231, and both ends of the slider 22 are slidably connected to the two first connecting portions 231 respectively. The wedge 25 is slidably mounted on the base 23 via a slide rail 29. The wedge 25 is located below the slider 22. The wedge 25 has an inclined connecting surface, and the bottom surface of the slider 22 is an inclined surface that matches the connecting surface. The slider 22 and the wedge 25 are slidably connected. The lead screw 26 is located between the two first connecting parts 231. The two ends of the lead screw 26 are rotatably connected to the two first connecting parts 231 respectively. The lead screw 26 passes through the wedge 25 and is threaded. The first servo motor 24 is mounted on the bottom surface of the base 23, and the output end of the first servo motor 24 is drivenly connected to one end of the lead screw 26. With this configuration, the first servo motor 24 outputs a forward or reverse rotation action to drive the lead screw 26 to drive the wedge 25 to slide left and right on the base 23. When the wedge 25 slides, it drives the slider 22 to move up and down through the inclined surface, thereby causing the pressure roller 2 mounted on the slider 22 to move up and down, thereby adjusting the contact position between the pressure roller 2 and the pipe and the force applied to the pipe. Furthermore, a dovetail groove is formed on the inclined surface of the bottom of the base 23, and a dovetail portion protrudes from the inclined surface of the wedge 25 to match the dovetail groove. The dovetail portion is inserted into the dovetail groove and slides in fit, thereby enabling the wedge 25 to drive the slider 22 to move up and down when it moves left and right. Furthermore, a front baffle 233 is provided between the two first connecting parts to block the wedge and part of the slider.

[0050] To make the equipment structure more compact, in this embodiment, such as Figure 4-7As shown, the top of the slider 22 has an opening 221 and two positioning slots. The opening 221 extends rearward through the slider 22 and is located between the two positioning slots, both of which are connected to the opening 221. A rotating shaft passes through the pressure roller 2, which is located inside the opening 221. Part of the pressure roller 2 protrudes from the upper side of the slider 22, and part of the pressure roller 2 protrudes from the rear side of the slider 22. The two ends of the rotating shaft 27 are respectively mounted on two positioning blocks 28, and the two positioning blocks 28 are respectively fixed in the two positioning slots. This makes the lifting mechanism more compact and facilitates the positioning and installation of the pressure roller 2. Furthermore, a transmission groove is provided on the side of the base 23, one end of the lead screw 26 extends into the transmission groove, the output end of the first servo motor 24 extends into the transmission groove, a first gear is installed on the lead screw 26, a second gear is installed on the output end of the first servo motor 24, the first gear and the second gear mesh, and a side baffle 232 for sealing the transmission groove is fixedly installed on the side of the base 23.

[0051] To facilitate the installation of slider 22, in this embodiment, as follows: Figure 4-7 As shown, the bending die 1 is fixed to the front end of the mounting base 15. The die hole 11 of the bending die 1 communicates with the through hole of the mounting base 15. Sliding grooves 2311 are provided on the end faces of the two first connecting parts 231 on the base 23, which are close to each other. The sliding grooves 2311 extend rearward through the first connecting parts 231. Sliding parts 222 protrude from both the left and right ends of the slider 22. Thus, when installing the slider 22, the sliding parts 222 of the slider 22 can be inserted from back to front into the two sliding grooves 2311. The base 23 is fixed. First, two pads 2312 are fixed to the rear ends of the two first connecting parts 231 respectively. Then, the pads 2312 are fixed to the front end of the mounting base 15 with multiple bolts. The bending mold 1 is located between the two pads. The pads 2312 can also block the rear end of the sliding groove 2311. Part of the base 23 is located below the mounting base 15 and is fixedly connected with bolts. This completes the connection between the slider 22 and the base 23, and also completes the connection between the base 23 and the bending mold 1. The components are easy to connect and easy to position. Furthermore, the mounting base is provided with an inclined clearance groove 16, which extends forward and passes through the bending mold 1. In this way, interference from other equipment can be avoided when processing long pipes.

[0052] To improve the movement accuracy of the slider 22 and prevent it from swaying during its up-and-down movement, in this embodiment, a vertically arranged first friction plate is fixedly installed at the front end of each of the two pads 2312, a second friction plate is installed on the sidewalls of the two sliding grooves 2311 that are far apart from each other, and a third friction plate is installed on the front side of each of the two sliding grooves 2311. The first friction plate, the second friction plate, and the third friction plate all abut against the sliding part of the slider 22, thereby improving the machining accuracy of the equipment.

[0053] To facilitate the driving of the bending mold 1, in this embodiment, the mounting base 15 is rotatably mounted on a bracket. The bracket includes a base plate 14 and two mounting plates 12. The two mounting plates 12 are arranged horizontally and fixed to the base plate 14. The mounting base 15 is located between the two mounting plates 12 and is rotatably connected. A second servo motor 13 is mounted on one of the mounting plates 12, and the output end of the second servo motor 13 is connected to the second connecting part 151 protruding from the mounting base 15. Furthermore, a limiting rod 5 is fixedly installed between the two mounting plates 12. The limiting rod is located above the rear side of the mounting base 15 to prevent the forming part of the tube from being too long and interfering with the guiding mechanism.

[0054] To achieve free bending, this embodiment also includes a third servo motor for driving the support to rotate, a fourth servo motor for driving the support to move left and right, and a fifth servo motor for driving the support to move up and down. In this embodiment, the support is rotatably mounted on a base, the third servo motor is mounted on the base and drives the support to rotate; the base is slidably mounted on a horizontal guide rail, the fourth servo motor is mounted on the horizontal guide rail and drives the base to move left and right; the horizontal guide rail is slidably mounted on a vertical guide rail, the fifth servo motor is mounted on the vertical guide rail and drives the horizontal support to move up and down.

[0055] In this embodiment, the guiding mechanism and the pushing mechanism can be referenced from patent documents with publication numbers CN111545608B, US7290422B2, CN100506419C, CN101707940B, EP1413369B1, etc.

[0056] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A free bending forming device, comprising a bending die (1) and a guiding mechanism (4), characterized in that, It also includes a pressure roller (2) for abutting the outside of the bent portion of the pipe protruding from the die hole (11) of the bending die (1). A base (23) is fixedly installed on the bending die (1), and the pressure roller (2) is rotatably installed on the base (23). The die hole (11) of the bending die (1) includes a front sidewall (111) and a rear sidewall (112). The front sidewall (111) and the rear sidewall (112) both extend from the outside to the inside and intersect in the die hole (11). The cross section at the intersection of the front sidewall (111) and the rear sidewall (112) is the middle surface of the bending die. The cross section of the front sidewall (111) is an arc surface with the radius gradually decreasing from the outside to the inside, and the cross section of the rear sidewall (112) is an arc surface with the radius gradually decreasing from the outside to the inside, so that the die hole (11) presents a state of convexity in the middle.

2. The free bending forming device according to claim 1, characterized in that: The pressure roller (2) is mounted on the base (23) in such a way that it can be close to or away from the axis of the die hole (11) of the bending die (1).

3. The free bending forming device according to claim 2, characterized in that: A slider that slides up and down is installed on the base (23). The slider is driven to move up and down by the first servo motor. The pressure roller (2) is installed on the slider.

4. The free bending forming device according to claim 3, characterized in that: A wedge that slides left and right is installed on the base (23). The slider is located above the wedge. The slider has an inclined surface that matches the wedge and the two slide together. So when the wedge moves left and right on the base (23), it can drive the slider to move up and down. The wedge is driven to move left and right by the first servo motor.

5. The free bending forming device according to claim 4, characterized in that: The base (23) has two first connecting parts protruding on it. The wedge and the slider are both located between the two first connecting parts. The left and right ends of the slider are respectively connected to the two first connecting parts in a sliding manner, and the wedge slides left and right between the two first connecting parts.

6. The free bending forming device according to claim 1, characterized in that: An annular groove (21) is provided on the outer circumference of the pressure roller (2).

7. The free bending forming device according to claim 6, characterized in that: The inner diameter of the cross-section of the annular groove (21) is not less than the outer diameter of the pipe fitting (3).

8. The free bending forming device according to claim 7, characterized in that: The longitudinal section of the annular groove (21) and the longitudinal section of the mold hole (11) are located in the same plane.

9. The free bending forming device according to claim 1, characterized in that: The bending die (1) is provided with a clearance groove (16); the bending die (1) is rotatably mounted on the bracket and driven to rotate back and forth by the second servo motor; a limiting rod (5) is fixedly installed on the bracket, and the limiting rod (5) is located above and behind the bending die (1).

10. A method for forming small-radius bending, characterized in that: Using any one of the free bending forming devices as described in any one of claims 1-9, during the bending forming process of the pipe, the pressure roller always presses firmly against the outer side of the already bent portion of the pipe.

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