Hollow tube bending system and bending method

Abstract

The present invention relates to the technical field of hollow tube forming, and in particular, to a hollow tube bending system and a bending method. A forming die, a supporting die and a hollow tube; the forming die has an extrusion channel, the extrusion channel includes a straight channel and a bending channel, the hollow tube bending system has a forming state, the forming state includes a first tube located in the bending channel, and a second tube is in a bent state and located in the bending channel, the supporting die includes a supporting shaft and a thread groove assembly, the thread groove assembly includes a first section spiral groove, a second section spiral groove, a third section spiral groove and a fourth section spiral groove which are sequentially spirally arranged on the outer circumference of the supporting shaft, the supporting shaft is located inside the hollow tube, the first section spiral groove, the second section spiral groove and the third section spiral groove are located in the bending channel, and the fourth section spiral groove is located in the straight channel, according to the depth and / or width of the four sections spiral grooves, the first section spiral groove < the third section spiral groove < the third section spiral groove < the fourth section spiral groove, thereby realizing rapid removal of the supporting shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of hollow tube forming, and in particular to a hollow tube bending system and a bending method. Background Art

[0002] Titanium alloy has the characteristics of low density, high specific strength and strong corrosion resistance. It has been widely used in the fields of aviation, aerospace, chemical industry and marine engineering. In the chemical industry and marine engineering industry, a large number of equipment need to use titanium alloy flow-through parts, among which titanium alloy elbows are relatively typical parts. In the industry, elbow parts are mostly processed and manufactured by profile bending + welding (flange or joint). With the improvement of equipment performance, more and more elbow parts require overall processing and manufacturing to improve their safety.

[0003] At present, there are commercial products and automated processing equipment for the second tube of ordinary pure titanium (TA1, TA2) profiles, but they are only suitable for simple thin-walled (≤4mm) tubes. For parts with wall thickness >4mm and structures such as flanges or joints and made of medium-to-high-strength titanium alloys such as TC4 or TA15, it is difficult to bend and process them as a whole through bending automation equipment. Although the casting or 3D printing + machining method can obtain parts with an overall hollow elbow structure, the material utilization rate and processing efficiency are low, and the overall manufacturing cost is high. And when the parts are processed into elbows. Summary of the invention

[0004] In order to solve the problem of how to remove the supporting shaft, the present invention provides a hollow tube bending system and a bending method.

[0005] According to a first aspect of the present invention, a hollow tube bending system comprises:

[0006] Forming dies, support dies and hollow tubes;

[0007] The forming die has an extrusion channel, the extrusion channel includes a straight channel and a bending channel, and the straight channel is connected to the bending channel;

[0008] The hollow tube includes a first tube and a second tube, the first tube is fixedly connected to the second tube, and the first tube is communicated with the second tube; the hollow tube bending system has a forming state, the forming state includes the first tube being located in the bending channel, the outer peripheral surface of the first tube abutting against the straight channel, the second tube being in a bent state and located in the bending channel, and the outer peripheral surface of the second tube abutting against the bending channel;

[0009] The supporting mold includes a supporting shaft and a thread groove assembly, and the thread groove assembly is arranged on the outer circumferential surface of the supporting shaft. The thread groove assembly includes a first section of spiral groove, a second section of spiral groove, a third section of spiral groove and a fourth section of spiral groove which are spirally arranged on the outer circumferential surface of the supporting shaft in sequence, and the four sections of spiral grooves can be connected to each other. Both ends of the supporting shaft have spiral groove openings connected to the four sections of spiral grooves. The supporting shaft is located inside the hollow tube, and the outer circumferential surface of the supporting shaft abuts against the hollow tube. The first section of spiral groove, the second section of spiral groove and the third section of spiral groove are located in the bending channel, and the fourth section of spiral groove is located in the straight channel. According to the depth and / or width of the four sections of spiral grooves, the first section of spiral groove < the third section of spiral groove < the third section of spiral groove < the fourth section of spiral groove.

[0010] According to an embodiment of the present invention, the side wall of the spiral groove is an inclined surface, a tooth surface, or an inclined surface with a tooth surface.

[0011] According to one embodiment of the present invention, the forming die comprises a positioning assembly and a bending assembly, and the positioning assembly and the bending assembly are arranged side by side;

[0012] The positioning assembly includes an upper positioning unit and a lower positioning unit, the upper positioning unit is arranged opposite to the lower positioning unit; the upper positioning unit includes a first positioning plate and a first positioning groove, the first positioning groove is arranged at the bottom of the first positioning plate; the lower positioning unit includes a second positioning plate and a second positioning groove, the second positioning groove is arranged at the top of the second positioning plate, the first positioning groove corresponds to the second positioning groove, and the first positioning groove and the second positioning groove constitute the linear channel;

[0013] The bending assembly includes an upper bending unit and a lower bending unit, and the upper bending unit is arranged opposite to the lower bending unit; the upper bending unit includes a first bending plate and a first bending groove, and the first bending groove is arranged at the bottom of the first bending plate; the lower bending unit includes a second bending plate and a second bending groove, and the second bending groove is arranged at the top of the second bending plate, the first bending groove corresponds to the second bending groove, and the first bending groove and the second bending groove constitute the bending channel; the first bending groove extends in a direction away from the positioning assembly and bends in a direction close to the second bending plate, and the bending direction of the second bending groove is consistent with the bending direction of the first bending groove; the first bending groove and the first positioning groove have the same axis of symmetry, and the second bending groove and the second positioning groove have the same axis of symmetry.

[0014] According to an embodiment of the present invention, the first tube has a first force-bearing portion, a second force-bearing portion and a third force-bearing portion, the first force-bearing portion corresponds to the first section of the spiral groove, the second force-bearing portion corresponds to the second section of the spiral groove, and the third force-bearing portion corresponds to the third section of the spiral groove; the second tube has a fourth force-bearing portion, and the fourth force-bearing portion is arranged opposite to the fourth section of the spiral groove; the force relationship of the four force-bearing portions is: the first force-bearing portion> the third force-bearing portion> the second force-bearing portion> the fourth force-bearing portion;

[0015] The first bending groove has a first pressure portion, a second pressure portion and a third pressure portion, the first pressure portion corresponds to the first force-bearing portion, the second pressure portion corresponds to the second force-bearing portion, and the third pressure portion corresponds to the third force-bearing portion; the first positioning groove is provided with a fourth pressure portion, and the fourth pressure portion is arranged opposite to the fourth force-bearing portion; the pressure relationship of the four pressure portions is: first pressure portion>third pressure portion>second pressure portion>fourth pressure portion.

[0016] According to one embodiment of the present invention, the upper positioning unit further includes a third positioning plate and a pre-tightening member;

[0017] The preload member comprises a first guide shaft, a spring and a first guide hole, wherein the first guide hole is arranged on the first positioning plate, the spring is sleeved on the first guide shaft, one end of the first guide shaft is fixedly connected to the third positioning plate, the other end of the first guide shaft is connected to the first guide hole, the first guide hole is provided with a clamping portion, and the first guide shaft is provided with a clamping block that can be connected to the clamping portion;

[0018] The forming state includes that the first positioning plate and the third positioning plate are in contact with each other, the spring is in a compressed state and is located in the first guide hole, and there is a gap between the clamping block and the clamping portion.

[0019] According to one embodiment of the present invention, the positioning assembly further comprises a locking unit;

[0020] The locking unit includes a locking hook and a locking protrusion, the locking hook is rotatably connected to the first positioning plate, the locking protrusion is fixedly connected to the second positioning plate, and the formed state includes the locking hook and the locking protrusion being clamped together.

[0021] According to an embodiment of the present invention, the locking hook has a first abutting surface that is engaged with the locking protrusion, the first abutting surface is provided with a groove, and the end of the locking protrusion has an arc surface that can slide in contact with the groove.

[0022] According to one embodiment of the present invention, the forming die further comprises a condensation component;

[0023] The condensation assembly includes a first condensation tube, a second condensation tube and a third condensation tube. The first positioning plate is provided with a first condensation groove for accommodating the first condensation tube, the first bending plate is provided with a second condensation groove for accommodating the second condensation tube, and the second positioning plate and the second bending plate are provided with a third condensation groove for accommodating the third condensation tube.

[0024] According to one embodiment of the present invention, the support shaft is provided with a hollow channel, and the hollow channel can be communicated with the four sections of the spiral groove.

[0025] According to a second aspect of the present invention, the present invention provides a hollow tube bending method, comprising the following steps:

[0026] heating the hollow tube until the temperature of the hollow tube is a first temperature, and inserting a support shaft into the hollow tube;

[0027] The foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the

[0028] The hollow tube is maintained in a state of forming a second tube until the first temperature drops to a second temperature, and the hollow tube is immersed in a dissolving liquid, the dissolving liquid flows into the spiral groove on the support shaft, and the dissolving liquid dissolves the support shaft to obtain a bent tube.

[0029] According to one embodiment of the present invention, during the process in which the driving component drives the first bending plate and the third positioning plate to move, the hollow tube bending system has a hollow tube installation state, an unformed state and a formed state that change in sequence; the hollow tube installation state includes one end of the hollow tube being located on the second positioning groove, the other end of the hollow tube being suspended between the first bending groove and the second bending groove, and there is a spacing between the first positioning plate and the third positioning plate; the unformed state includes the first positioning groove abutting against the outer peripheral surface of the hollow tube based on the hollow tube installation state, the spacing between the first positioning plate and the third positioning plate remains unchanged or becomes smaller, and the first pressure part of the first bending groove abuts or does not abut against the outer peripheral surface of the hollow tube; the formed state includes the first bending groove and the second bending groove abutting against the outer peripheral surface of the hollow tube based on the unformed state, the first positioning plate abuts against the third positioning plate, and one end of the hollow tube forms the second tube.

[0030] According to one embodiment of the present invention, in the process from the unformed state to the formed state, the hollow tube bending system has a first extrusion state, a second extrusion state and a third extrusion state that change in sequence, the first extrusion state includes the first pressure portion abutting or not abutting against the outer circumferential surface of the hollow tube, and the fourth pressure portion of the first positioning groove abutting against the outer circumferential surface of the hollow tube; based on the first extrusion state, the second extrusion state includes the first pressure portion abutting against the outer circumferential surface of the hollow tube, and the second pressure portion of the first bending groove abutting against the outer circumferential surface of the hollow tube; the third extrusion state includes the third pressure portion of the first bending groove abutting against the outer circumferential wall of the hollow tube based on the second extrusion state.

[0031] According to one embodiment of the present invention, the hollow tube is made of titanium alloy, the support shaft is made of low carbon steel, and the dissolving liquid includes, by mass fraction, 25% to 40% nitric acid solution, or a mixed solution of 20% to 25% hydrochloric acid and +3% to 5% nitric acid.

[0032] To solve the problem of how to remove the support shaft, the present invention has the following advantages:

[0033] 1. In the present invention, a first section of spiral groove, a second section of spiral groove, a third section of spiral groove and a fourth section of spiral groove are sequentially spirally arranged on the outer circumference of the support shaft, the four sections of spiral grooves can be connected to each other, both ends of the support shaft have spiral groove openings connected to the four sections of spiral grooves, and according to the position and size of the four sections of spiral grooves, i.e., the depth and / or width, the area of ​​the spiral groove is increased while ensuring the performance of the support shaft, so as to facilitate the rapid removal of the support shaft by the dissolving liquid.

[0034] 2. In the present invention, the first temperature is reduced to the second temperature as a reference for taking out the hollow tube, providing a suitable deformation time for the hollow tube to form a bent state, and avoiding the rebound phenomenon of the bent second tube. The process of bending the hollow tube is easy to operate, and the overall processed second tube improves the dimensional accuracy and surface quality of the second tube. The overall processing improves the working effect, has the advantage of greatly reducing the production cost, and is suitable for popularization and application. In addition, a support shaft is installed into the hollow tube, and then the hollow tube is bent. The support shaft has a supporting effect on the hollow tube, which can avoid the second tube structure from changing diameter, wrinkling, and cracking when the hollow tube is bent. In this embodiment, it is easy to remove the support shaft from the hollow tube, and the method for obtaining a bent tube is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic structural diagram of a forming die according to an embodiment is shown;

[0036] Figure 2 A schematic cross-sectional structure diagram of a forming die according to an embodiment is shown;

[0037] Figure 3 A schematic diagram of the structure of a die forming an extrusion channel in an embodiment is shown;

[0038] Figure 4 A schematic structural diagram of a support shaft according to an embodiment is shown;

[0039] Figure 5 A structural schematic diagram showing a hollow tube bending system in an embodiment of the present invention in a state where a hollow tube is installed;

[0040] Figure 6 A schematic cross-sectional structure diagram of a hollow tube bending system in an embodiment of the present invention is shown;

[0041] Figure 7 A schematic cross-sectional structure diagram of an unformed state of a hollow tube bending system according to an embodiment is shown;

[0042] Figure 8 A schematic cross-sectional structure diagram of a hollow tube bending system in a forming state according to an embodiment is shown;

[0043] Fig. 9 A schematic diagram of the structure of an anti-unhooking embodiment is shown;

[0044] Fig.10 A schematic diagram of the structure of a first condenser tube, a second condenser tube and a third condenser tube in an embodiment is shown;

[0045] Fig.11 A flow chart of hollow tube bending according to an embodiment is shown.

[0046] Reference numerals: 01-forming mold; 11-positioning assembly; 111-upper positioning unit; 1111-third positioning plate; 1112-first positioning plate; 1113-first positioning groove; 1114-first clamping groove; 1115-preload; 11151-first guide shaft; 11152-spring 11153-first guide hole; 112-lower positioning unit; 1121-second positioning plate; 1122-second positioning groove; 1123-second clamping groove; 113-locking unit; 1131-locking hook; 1132-locking protrusion; 12-bending assembly; 121-upper bending unit; 1211-first bending plate; 1212- The first bending groove; 122-lower bending unit; 1221-second bending plate; 1222-second bending groove; 123-guide unit; 1231-second guide hole; 1232-second guide shaft; 13-extrusion channel; 131-straight channel; 132-bending channel; 14-condensation assembly; 141-first condensation tube; 142-second condensation tube; 143-third condensation tube; 02-hollow tube; 21-first tube; 22-second tube; 03-support mold; 31-support shaft; 32-thread groove assembly; 321-first section spiral groove; 322-second section spiral groove; 323-third section spiral groove; 324-fourth section spiral groove. DETAILED DESCRIPTION

[0047] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0048] As used herein, the term "including" and its variants are to be interpreted as open terms meaning "including but not limited to". The term "based on" is to be interpreted as "based at least in part on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like is based on the orientation or position relationship shown in the drawings. These terms are mainly for better describing the present application and its embodiments, and are not used to limit the indicated system, element or component to have a specific orientation, or to be constructed and operated in a specific orientation. In addition, in addition to being used to indicate an orientation or position relationship, some of the above terms may also be used to indicate other meanings, such as the term "upper" may also be used to indicate a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances. In addition, the terms "install", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two systems, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different systems, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated systems, elements or components. Unless otherwise specified, "plurality" means two or more.

[0049] This embodiment discloses a hollow tube bending system, such as Figure 1-8 As shown, it may include:

[0050] Forming die 01, supporting die 03 and hollow tube 02;

[0051] The forming die 01 has an extrusion channel 13, and the extrusion channel 13 includes a straight channel 131 and a bending channel 132, and the straight channel 131 is connected to the bending channel 132;

[0052] The hollow tube 02 includes a first tube 21 and a second tube 22, the first tube 21 is fixedly connected to the second tube 22, and the first tube 21 is communicated with the second tube 22; the hollow tube bending system has a forming state, the forming state includes the first tube 21 being located in the bending channel 132, the outer peripheral surface of the first tube 21 abutting against the straight channel 131, the second tube 22 being in a bent state and located in the bending channel 132, and the outer peripheral surface of the second tube 22 abutting against the bending channel 132;

[0053] The supporting mold 03 includes a supporting shaft 31 and a thread groove assembly 32, wherein the thread groove assembly 32 is arranged on the outer peripheral surface of the supporting shaft 31, and the thread groove assembly 32 includes a first section spiral groove 321, a second section spiral groove 322, a third section spiral groove 323 and a fourth section spiral groove 324 which are spirally arranged on the outer peripheral surface of the supporting shaft 31 in sequence, and the four sections of the spiral grooves can be connected to each other, and both ends of the supporting shaft 31 have spiral groove openings connected to the four sections of the spiral grooves, and the supporting shaft 31 is located inside the hollow tube 02, and the outer peripheral surface of the supporting shaft 31 abuts against the hollow tube 02, the first section spiral groove 321, the second section spiral groove 322 and the third section spiral groove 323 are located in the bending channel 132, and the fourth section spiral groove 324 is located in the straight channel 131, and according to the depth and / or width of the four sections of the spiral grooves, the first section spiral groove 321 < the third section spiral groove 323 < the third section spiral groove 323 < the fourth section spiral groove 324.

[0054] When carrying out this embodiment, the hollow tube bending system is in a forming state, that is, the hollow tube 02 is bent to form a bent tube state, and the forming mold 01 bends the hollow tube 02 into a bent state. The hollow tube 02 in the bent state is located in the extrusion channel 13. Since the bending channel 132 is a bent hollow tube 02, that is, the bending channel 132 applies pressure to the hollow tube 02, thereby bending the hollow tube 02. Since the hollow tube 02 is easily deformed when it is bent, a support shaft 31 is added to the hollow tube 02. The support shaft 31 provides support performance for the hollow tube 02 when it is subjected to extrusion pressure, which can avoid the hollow tube 02 from changing diameter, wrinkling, and cracking when it is bent. After the hollow tube 02 is bent, the support shaft 31 is also bent. The support shaft 31 is in the state at this time, and it is not easy to take out the support shaft 31 from the hollow tube 02. Based on this, the support shaft 31 can be removed from the hollow tube 02 by means of a dissolving liquid. Therefore, a threaded groove component 32 is provided on the outer circumferential surface of the support shaft 31. Through the provision of the threaded groove component 32, the dissolving liquid that dissolves the support shaft 31 has more contact area with the support shaft 31 through the threaded groove component 32, so that the support shaft 31 can be quickly removed. Furthermore, in order to ensure the supporting performance of the support shaft 31 and to quickly remove the support shaft 31, a first section spiral groove 321, a second section spiral groove 322, a third section spiral groove 323 and a fourth section spiral groove 324 are spirally provided on the outer circumferential surface of the support shaft 31 in sequence. The four sections of the spiral grooves can be interconnected, and both ends of the support shaft 31 have a spiral groove connected to the four sections. The spiral groove opening connected by the groove, and the setting method according to the position and size of the four-section spiral groove, that is, the depth and / or width, make the size of the spiral groove be adaptively set according to the amount of pressure applied by the extrusion channel 13 to the support shaft 31. Since the part where the bending channel 132 corresponding to the first-section spiral groove 321 abuts against the hollow tube 02 is the part with the largest bending amount of the hollow tube 02, the part of the hollow tube 02 with the bending amount is subjected to the greatest pressure. Therefore, the depth and / or width of the first-section spiral groove 321 is set to the minimum to ensure the supporting performance of the support shaft 31, and the bending channel 132 corresponding to the third-section spiral groove 323 is close to the straight channel 131. When the hollow tube 02 corresponding to the third-section spiral groove 323 is subjected to the extrusion pressure, the straight channel 131 is located The abutment between the first tube 21 of the hollow tube 02 on the straight channel 131 forms a reverse force applied to the straight channel 131. The first reverse force on the straight channel 131 causes the second tube 22 corresponding to the portion of the hollow tube 02 and the third section of the spiral groove 323 to be subjected to a pressure greater than that of the portion of the second tube 22 corresponding to the second section of the spiral groove 322. This reduces the depth and / or width of the spiral groove of the support shaft 31 subjected to a large extrusion pressure to ensure the performance of the support shaft 31, and increases the depth and / or width of the spiral groove of the support shaft 31 subjected to a small extrusion pressure. While ensuring the performance of the support shaft 31, the area of ​​the spiral groove is increased to facilitate the dissolving liquid to enter the spiral groove through the spiral groove mouth, thereby quickly removing the support shaft 31.

[0055] According to an embodiment of the present invention, the side wall of the spiral groove is an inclined surface, a tooth surface, or an inclined surface with a tooth surface.

[0056] In this embodiment, the area of ​​the spiral groove is increased by providing the spiral groove.

[0057] According to one embodiment of the present invention, Figure 1-8 As shown, the forming die 01 includes a positioning component 11 and a bending component 12, and the positioning component 11 and the bending component 12 are arranged side by side;

[0058] The positioning assembly 11 includes an upper positioning unit 111 and a lower positioning unit 112, wherein the upper positioning unit 111 is arranged opposite to the lower positioning unit 112; the upper positioning unit 111 includes a first positioning plate 1112 and a first positioning groove 1113, wherein the first positioning groove 1113 is arranged at the bottom of the first positioning plate 1112; the lower positioning unit 112 includes a second positioning plate 1121 and a second positioning groove 1122, wherein the second positioning groove 1122 is arranged at the top of the second positioning plate 1121, the first positioning groove 1113 corresponds to the second positioning groove 1122, and the first positioning groove 1113 and the second positioning groove 1122 constitute the linear channel 131;

[0059] The bending assembly 12 includes an upper bending unit 121 and a lower bending unit 122, wherein the upper bending unit 121 is arranged opposite to the lower bending unit 122; the upper bending unit 121 includes a first bending plate 1211 and a first bending groove 1212, wherein the first bending groove 1212 is arranged at the bottom of the first bending plate 1211; the lower bending unit 122 includes a second bending plate 1221 and a second bending groove 1222, wherein the second bending groove 1222 is arranged at the top of the second bending plate 1221, and the first bending groove 1212 and the second bending groove 1212 are arranged at the top of the second bending plate 1221. The first bending groove 1212 and the second bending groove 1222 correspond to each other, and the first bending groove 1212 and the second bending groove 1222 constitute the bending channel 132; the first bending groove 1212 extends in the direction away from the positioning assembly 11 and bends in the direction close to the second bending plate 1221, and the bending direction of the second bending groove 1222 is consistent with the bending direction of the first bending groove 1212; the first bending groove 1212 and the first positioning groove 1113 have the same axis of symmetry, and the second bending groove 1222 and the second positioning groove 1122 have the same axis of symmetry.

[0060] In this embodiment, by setting the first positioning plate 1112 and the first bending plate 1211, when the hollow tube bending system is in the process of forming a forming state, when the first positioning plate 1112 is pressed down, the first positioning groove 1113 first abuts against the first tube 21 of the hollow tube 02, and the first positioning groove 1113 and the second positioning groove 1122 cooperate to position the hollow first tube 21, so that when the first bending plate 1211 applies a bending extrusion pressure to the second tube 22 of the hollow tube 02, the second tube 22 is prevented from warping and moving, etc., which may affect the forming of the hollow tube 02. The first bending plate 1211 and the second bending plate 1221 cooperate to bend the hollow tube 02. The first bending groove 1212 and the second bending groove 1222 cooperate to provide a suitable accommodation space for the hollow tube 02 to ensure the shape of the hollow tube 02 after bending. The first bending groove 1212 and the first positioning groove 1113 have the same symmetry axis, and the bending groove and the second positioning groove 1122 have the same symmetry axis, which further ensures the shape of the hollow tube 02 after bending and also facilitates the first bending plate 1211 to bend the hollow tube 02.

[0061] In some embodiments, the curvature of the first bending groove 1212 and the second bending groove 1222 is obtained according to the curvature of the bending section of the second tube 22 of the required hollow tube 02 to ensure that the shape of the second tube 22 after bending the hollow tube 02 is consistent with the required shape of the second tube 22.

[0062] In some embodiments, the length of the first positioning groove 1113 is less than the length of the first tube 21 of the hollow tube 02, ensuring that the hollow tube 02 with flanges or joints can be located outside the extrusion channel 13 to prevent the flanges or joints from affecting the bending of the hollow tube 02. The depth and / or width of the spiral groove arranged on the outer peripheral surface of the support shaft 31 corresponding to the extrusion channel 13 is greater than the depth and / or width of the fourth section spiral groove 324, such as Figure 5-8 shown.

[0063] In some embodiments, Figure 1-3 As shown, the first positioning plate 1112 is provided with a first clamping groove 1114, and the second positioning plate 1121 is provided with a second clamping groove 1123, and the first clamping groove 1114 corresponds to the second clamping groove 1123. Through the corresponding arrangement of the first clamping groove 1114 and the second clamping groove 1123, the hollow tube 02 with the flange can be accommodated, and the first clamping groove 1114 and the second clamping groove 1123 cooperate to position the flange, so that the hollow tube 02 can also be positioned when it is bent.

[0064] In some embodiments, the forming mold 01 further includes a driving assembly. When the hollow tube bending system is in the forming state, the driving end of the driving assembly can be connected to the first positioning plate 1112 and the first bending plate 1211 at the same time. Then, after the outer peripheral surface of the second tube 22 of the hollow tube 02 abuts against the first bending groove 1212 and the second bending groove 1222, the outer peripheral surface of the first tube 21 abuts against the first positioning groove 1113 and the second positioning groove 1122.

[0065] Preferably, the driving end of the driving component is respectively connected to the first positioning plate 1112 and the first bending plate 1211 at the same time, and the driving component can first drive the first positioning plate 1112 to move, so that the outer peripheral surface of the first tube 21 abuts against the first positioning groove 1113 and the second positioning groove 1122, so that after the straight channel 131 positions the first tube 21, the driving component drives the first bending plate 1211 to move, and the first bending plate 1211 applies bending extrusion pressure to the second tube 22, so as to better bend the hollow tube 02.

[0066] In some embodiments, the forming mold 01 includes a guide unit 123, the guide unit 123 includes a second guide hole 1231 and a second guide shaft 1232, the second guide hole 1231 is arranged on the first bending plate 1211, the second guide shaft 1232 is arranged on the second bending plate 1221, and the second guide shaft 1232 can be slidably connected to the second guide hole 1231. Through the arrangement of the second guide hole 1231 and the second guide shaft 1232, a guiding function is provided for the movement of the first bending plate 1211.

[0067] Or the second bending plate 1221 is provided with a fixing groove which is interference fit with the second guide shaft 1232 , and the second guide shaft 1232 is pre-embedded in the fixing groove to facilitate the removal of the second guide shaft 1232 .

[0068] According to one embodiment of the present invention, Figure 4-8 As shown, the first tube 21 has a first force-bearing portion, a second force-bearing portion and a third force-bearing portion, the first force-bearing portion corresponds to the first section spiral groove 321, the second force-bearing portion corresponds to the second section spiral groove 322, and the third force-bearing portion corresponds to the third section spiral groove 323; the second tube 22 has a fourth force-bearing portion, and the fourth force-bearing portion is arranged opposite to the fourth section spiral groove 324; the force relationship of the four force-bearing portions is: the first force-bearing portion> the third force-bearing portion> the second force-bearing portion> the fourth force-bearing portion;

[0069] The first bending groove 1212 has a first pressure portion, a second pressure portion and a third pressure portion, the first pressure portion corresponds to the first force-bearing portion, the second pressure portion corresponds to the second force-bearing portion, and the third pressure portion corresponds to the third force-bearing portion; the first positioning groove 1113 is provided with a fourth pressure portion, and the fourth pressure portion is arranged opposite to the fourth force-bearing portion; the pressure relationship of the four pressure portions is: first pressure portion>third pressure portion>second pressure portion>fourth pressure portion.

[0070] In this embodiment, by setting the position correspondence between the force-bearing parts of the first tube 21 and the second tube 22 and the four-segment spiral grooves, as well as the position correspondence between the force-bearing parts of the first tube 21 and the second tube 22 and the pressure parts of the first bending groove 1212 and the second bending groove 1222, the support shaft 31 can ensure the supporting performance while increasing the contact area between the solution and the support shaft 31.

[0071] According to one embodiment of the present invention, Figure 1-8 As shown, the upper positioning unit 111 further includes a third positioning plate 1111 and a pre-tightening member 1115;

[0072] The preload member 1115 includes a first guide shaft 11151, a spring 11152 and a first guide hole 11153, wherein the first guide hole 11153 is provided on the first positioning plate 1112, the spring 11152 is sleeved on the first guide shaft 11151, one end of the first guide shaft 11151 is fixedly connected to the third positioning plate 1111, and the other end of the first guide shaft 11151 is connected to the first guide hole 11153, the first guide hole 11153 is provided with a clamping portion, and the first guide shaft 11151 is provided with a clamping block that can be connected to the clamping portion;

[0073] The forming state includes the first positioning plate 1112 abutting against the third positioning plate 1111, the spring 11152 is in a compressed state and is located in the first guide hole 11153, and there is a gap between the clamping block and the clamping portion.

[0074] In this embodiment, by setting the third positioning plate 1111, the first guide shaft 11151, the elastic sleeve and the first guide hole 11153, when the hollow tube bending system is in the forming state, a part of the spring 11152 is located in the first guide hole 11153, and the other part of the spring 11152 is located in the gap between the third positioning plate 1111 and the first positioning plate 1112, and the clamping portion abuts against the clamping block. Specifically, the space diameter of the first guide hole 11153 accommodating the clamping block is larger than the space diameter of the first guide hole 11153 accommodating the first guide shaft 11151, which is convenient for forming the clamping portion, and then for clamping the clamping block of the first guide shaft 11151 with the connectable portion. When the third positioning plate 1111 is pressed down in the direction close to the second template, the third positioning plate 1111 drives the first positioning plate 11 12 is pressed down, when the first positioning groove 1113 of the first positioning plate 1112 contacts the first tube 21 of the hollow tube 02, under the action of the spring 11152, the first positioning groove 1113 of the first positioning plate 1112 cooperates with the second positioning groove 1122 to provide a pre-tightening force for the first tube 21 of the hollow tube 02, that is, to position the hollow tube 02 to prevent the first tube 21 from tilting when the first bending groove 1212 abuts against the second tube 22 of the hollow tube 02. In the process of further pressing down the third positioning plate 1111, after the third positioning plate 1111 abuts against the first positioning plate 1112, the spring 11152 is completely located in the first guide hole 11153, and the guide shaft continues to slide along the first guide hole 11153. There is a spacing between the clamping portion and the clamping block, and the clamping portion is suspended in the first guide hole 11153. By setting the elastic sleeve, during the continuous downward pressure of the third positioning plate 1111 and the first bending plate 1211, the spring 11152 is compressed by the downward pressure force applied by the third positioning plate 1111, and the third positioning plate 1111 and the first positioning plate 1112 approach each other until the third positioning plate 1111 and the first positioning plate 1112 abut against each other, so that the compression process of the spring 11152 does not affect the cooperation of the first bending plate 1211 and the second bending plate 1221 with the bending hollow tube 02.

[0075] In some embodiments, a protrusion is provided on the side of the clamping block, and a sliding groove is provided on the side of the first guide hole 11153 for the protrusion to slide; or, a protrusion is provided on the first guide hole 11153, and a sliding groove is provided on the side of the first guide shaft 11151 for the protrusion to slide. When the third positioning plate 1111 and the first positioning plate 1112 are not in contact, the first positioning plate 1112 is only clamped with the clamping block by the clamping portion to form a positioning state, but the position of the first positioning plate 1112 may be unstable. By providing the protrusion and the sliding groove, the first positioning plate 1112 is prevented from deflecting on the first guide shaft 11151, and the connection stability between the first positioning plate 1112 and the first guide shaft 11151 is improved.

[0076] In some embodiments, since there is a distance between the third positioning plate 1111 and the first positioning plate 1112 when the hollow tube 02 forming system is in an unformed state, the distance between the third positioning plate 1111 and the first positioning plate 1112 can be set to be equal to or greater than the movement stroke of the first bending plate 1211 when it contacts the hollow tube 02 until the first bending groove 1212 and the second bending groove 1222 are fully in contact with the second tube 22 of the hollow tube 02, thereby ensuring that the structure of the first tube 21 is not deformed, and avoiding being affected by the first positioning plate 1112 and the third positioning plate 1111, resulting in the first bending plate 1211 being unable to continue to press down, causing the bent tube to be not formed in place.

[0077] In some embodiments, the third positioning plate 1111 is provided with a threaded channel for threaded connection of the first guide shaft 11151 , and the first guide shaft 11151 is partially connected to the threaded channel, thereby reserving a portion of the threaded channel, and the reserved portion of the threaded channel provides an anti-dead space for the first guide shaft 11151 .

[0078] In some embodiments, a protrusion is provided on the side of the clamping portion, and a sliding groove is provided on the side of the first guide groove for the protrusion to slide; or a protrusion is provided on the side of the first guide groove, and a sliding groove is provided on the side of the clamping portion for the protrusion to slide. It also prevents the second pressing plate from deflecting on the second guide shaft 1232, and provides reliable connection stability between the second pressing plate and the second guide shaft 1232.

[0079] In some embodiments, when the hollow tube 02 has a flange or a joint, one end having the flange or the joint is placed outside the mold.

[0080] According to one embodiment of the present invention, Figure 1 , 5 As shown in , 9, the positioning assembly 11 also includes a locking unit 113;

[0081] The locking unit 113 includes a locking hook 1131 and a locking protrusion 1132 . The locking hook 1131 is rotatably connected to the first positioning plate 1112 , and the locking protrusion 1132 is fixedly connected to the second positioning plate 1121 . The formed state includes the locking hook 1131 and the locking protrusion 1132 being clamped together.

[0082] In this embodiment, when the first positioning plate 1112 and the second positioning plate 1121 are approaching each other, the anti-disconnection hook will automatically separate outward after contacting the side end inclined surface of the locking protrusion 1132. When the first positioning plate 1112 and the second positioning plate 1121 are abutted, the locking hook 1131 is engaged with the locking protrusion 1132. When in the formed state, the locking hook 1131 is still engaged with the locking protrusion 1132. Through the setting of the locking unit 113, the first tube 21 of the hollow tube 02 is prevented from warping during the bending process of the hollow tube 02, thereby further providing a stable positioning capability for the first tube 21 of the hollow tube 02.

[0083] In some embodiments, both sides of the positioning assembly 11 are connected to the locking unit 113 to further improve the reliability of the structure.

[0084] According to one embodiment of the present invention, Figure 1 and Fig. 9 As shown, the locking hook 1131 has a first abutting surface that is engaged with the locking protrusion 1132, the first abutting surface is provided with a groove, and the end of the locking protrusion 1132 has an arc surface that can be in sliding contact with the groove.

[0085] In this embodiment, the locking protrusion 1132 is provided with an arc surface, so that when the first bending plate 1211 is pressed downward, the groove of the first abutting surface of the locking hook 1131 can easily slide into contact with the locking protrusion 1132, thereby reducing the wear caused by the contact between the first abutting surface and the locking protrusion 1132.

[0086] In some embodiments, the depth of the groove of the first abutting surface is 1 mm to 3 mm.

[0087] According to one embodiment of the present invention, Figure 1-8 and Fig.10 As shown, the forming mold 01 also includes a condensation component 14;

[0088] The condensation assembly 14 includes a first condensation tube 141, a second condensation tube 142 and a third condensation tube 143. The first positioning plate 1112 is provided with a first condensation groove for accommodating the first condensation tube 141, the first bending plate 1211 is provided with a second condensation groove for accommodating the second condensation tube 142, and the second positioning plate 1121 and the second bending plate 1221 are provided with a third condensation groove for accommodating the third condensation tube 143.

[0089] In this embodiment, through the arrangement of the first condenser 141, the second condenser 142 and the third condenser 143, low-temperature flowing water can be passed into the condenser to facilitate cooling of the first positioning plate 1112, the second positioning plate 1121, the first bending plate 1211 and the second bending plate 1221.

[0090] In some embodiments, the first positioning plate 1112 , the second positioning plate 1121 , the first bending plate 1211 and the second bending plate 1221 are provided with condensation grooves for accommodating the condensation tubes, and preferably there is a distance between the condensation grooves and the condensation tubes.

[0091] In some embodiments, the first positioning plate 1112, the second positioning plate 1121, the first bending plate 1211 and the second bending plate 1221 are each split into two plates, a groove is opened on each plate, and a condensation groove is obtained by assembling the first positioning plate 1112, the second positioning plate 1121, the first bending plate 1211 and the second bending plate 1221.

[0092] According to an embodiment of the present invention, the support shaft 31 is provided with a hollow channel, and the hollow channel can be communicated with the four sections of the spiral grooves.

[0093] In this embodiment, the area of ​​the support shaft 31 that can contact the dissolving liquid is increased.

[0094] In some embodiments, there are at least four hollow channels, and each hollow channel is connected to four sections of spiral grooves respectively.

[0095] According to the second aspect of the present invention, this embodiment provides a method for bending a hollow tube 02, such as Fig.11 As shown, the bending method includes the following steps:

[0096] Heating the hollow tube 02 until the temperature of the hollow tube 02 is a first temperature, and inserting the support shaft 31 into the hollow tube 02;

[0097] The hollow tube 02 is placed in the hollow tube bending system, and the driving component is connected to the third positioning plate 1111 and the first bending plate 1211, and the driving component drives the first bending plate 1211 to move in the direction close to the second bending plate 1221, and at the same time, the driving component drives the third positioning plate 1111 to drive the first positioning plate 1112 to move in the direction close to the second positioning plate 1121, until the first bending plate 1211 abuts against the second bending plate 1221, and the third positioning plate 1111 abuts against the first positioning plate 1112, and the outer peripheral surface of one end of the hollow tube 02 abuts against the first positioning groove 1113 of the first positioning plate 1112 and the second positioning groove 1122 of the second positioning plate 1121 to form a first tube 21 in a straight state, and the outer peripheral surface of the other end of the hollow tube 02 abuts against the first bending groove 1212 of the first bending plate 1211 and the second bending groove 1222 of the second bending plate 1221 to form a second tube 22 in a bent state;

[0098] The hollow tube 02 is maintained in a state of forming the second tube 22 until the first temperature drops to the second temperature, and the hollow tube 02 is immersed in a dissolving liquid, the dissolving liquid flows into the spiral groove on the support shaft 31, and the dissolving liquid dissolves the support shaft 31 to obtain a bent tube.

[0099] In this embodiment, the first temperature is reduced to the second temperature as a reference for taking out the hollow tube 02, providing a suitable deformation time for the hollow tube 02 to form a bent state, and avoiding the rebound phenomenon of the bent second tube 22. The process of bending the hollow tube 02 is easy to operate, and the overall processed second tube 22 improves the dimensional accuracy and surface quality of the second tube 22. The overall processing improves the working effect, has the advantage of greatly reducing the production cost, and is suitable for popularization and application. The support shaft 31 is installed into the hollow tube 02, and then the hollow tube 02 is bent. The support shaft 31 has a supporting effect on the hollow tube 02, which can avoid the second tube 22 structure from changing diameter, wrinkling, and cracking when the hollow tube 02 is bent. In this embodiment, it is easy to remove the support shaft 31 from the hollow tube 02, and the method for obtaining the bent tube is simple.

[0100] In some embodiments, the first temperature is 750°C-900°C, and the second temperature is 300°C-500°C.

[0101] In some embodiments, the difference between the inner diameter of the hollow tube 02 and the diameter of the support shaft 31 does not exceed 0.1 mm, so that the support shaft 31 is easy to insert into the hollow tube 02 and provides reliable support performance for the hollow tube 02.

[0102] In some embodiments, the length of the support shaft 31 may be consistent with the length of the hollow tube 02 .

[0103] In some embodiments, the difference between the inner diameter of the bending channel 132 formed by the first bending groove 1212 and the second bending groove 1222 and the inner diameter of the hollow tube 02 does not exceed 0.2 mm, and the difference between the inner diameter of the straight channel 131 formed by the first positioning groove 1113 and the second positioning groove 1122 and the inner diameter of the hollow tube 02 does not exceed 0.2 mm, further ensuring the reliability of the mold bending hollow tube 02.

[0104] In some embodiments, after the bent tube is taken out of the mold, condensed water is introduced into the condenser to cool the forming mold 01 to prevent the forming mold 01 from generating high temperature due to contact with the high-temperature hollow tube 02 and thus affecting its service life.

[0105] According to one embodiment of the present invention, Figure 5-8As shown, during the process in which the driving component drives the first bending plate 1211 and the third positioning plate 1111 to move, the hollow tube bending system has a state of installing the hollow tube 02, an unformed state and a formed state that change in sequence; the state of installing the hollow tube 02 includes that one end of the hollow tube 02 is located on the second positioning groove 1122, and the other end of the hollow tube 02 is suspended between the first bending groove 1212 and the second bending groove 1222, and there is a distance between the first positioning plate 1112 and the third positioning plate 1111; the unformed state includes based on the installation of the hollow tube 02 In the core tube 02 state, the first positioning groove 1113 abuts against the outer peripheral surface of the hollow tube 02, the distance between the first positioning plate 1112 and the third positioning plate 1111 remains unchanged or decreases, and the first pressure portion of the first bending groove 1212 abuts or does not abut against the outer peripheral surface of the hollow tube 02; the formed state includes the first bending groove 1212 and the second bending groove 1222 abutting against the outer peripheral surface of the hollow tube 02 based on the unformed state, the first positioning plate 1112 abuts against the third positioning plate 1111, and the second tube 22 is formed at one end of the hollow tube 02.

[0106] In this embodiment, the positioning groove is provided so that the positioning groove can accommodate the protrusion that is not at the end of the hollow tube 02, thereby preventing the protrusion from affecting the effect of the mold clamping the hollow tube 02.

[0107] According to one embodiment of the present invention, in the process from the unformed state to the formed state, the hollow tube bending system has a first extrusion state, a second extrusion state and a third extrusion state that change in sequence, the first extrusion state includes the first pressure portion abutting or not abutting against the outer peripheral surface of the hollow tube 02, and the fourth pressure portion of the first positioning groove 1113 abutting against the outer peripheral surface of the hollow tube 02; based on the first extrusion state, the second extrusion state includes the first pressure portion abutting against the outer peripheral surface of the hollow tube 02, and the second pressure portion of the first bending groove 1212 abutting against the outer peripheral surface of the hollow tube 02; the third extrusion state includes the third pressure portion of the first bending groove 1212 abutting against the outer peripheral wall of the hollow tube 02 based on the second extrusion state.

[0108] According to one embodiment of the present invention, the hollow tube 02 is made of titanium alloy, the support shaft 31 is made of low carbon steel, and the dissolving liquid includes 25%~40% nitric acid solution, or a mixed solution of 20%~25% hydrochloric acid and +3%~5% nitric acid by mass fraction.

[0109] In this embodiment, the hollow tube 02 and the support shaft 31 are made of different materials, so that when the dissolving liquid dissolves the support shaft 31 , the hollow tube 02 is not affected.

[0110] In some embodiments, the forming mold 01 may be made of heat-resistant steel or high-temperature alloy to ensure that the forming mold 01 can maintain sufficient strength when the forming mold 01 repeatedly contacts the heated hollow tube 02 .

[0111] Example 1

[0112] An overall processing method for a special-shaped titanium alloy thick-walled hollow elbow comprises the following steps:

[0113] (1) According to the straight state structure and size of the hollow tube 02 after unfolding, the outer shape and inner hole of the hollow tube 02 are processed in place by machining equipment; if the structure needs to be fine-machined after bending, a certain process margin can be reserved at the corresponding position according to the process requirements. The inner hole of the hollow tube 02 can be processed by drilling first and then boring, and the outer shape can be processed by turning or milling according to the specific structure of the workpiece.

[0114] (2) Design and manufacture a hollow tube bending system. The forming die 01 can be made of heat-resistant steel or high-temperature alloy to ensure that the die can maintain sufficient strength when repeatedly in contact with the high-temperature hollow tube 02.

[0115] (3) According to the actual size of the inner hole of the hollow tube 02 and the principle of clearance fit, a steel support shaft 31 is machined. The material of the support shaft 31 is Q235 low-carbon steel, and a spiral groove is machined on the outer circumference of the support shaft 31 by a CNC lathe.

[0116] (4) Install the steel support shaft 31 into the inner hole of the hollow tube 02;

[0117] (5) Place the hollow tube 02 in a heat treatment furnace or a heating furnace for heating. For the hollow tube 02 with a wall thickness of 10 mm to 20 mm, the heating temperature is set at 850°C to 900°C; for the hollow tube 02 with a wall thickness of 5 mm to 10 mm, the heating temperature is set at 750°C to 850°C;

[0118] (6) Take the hollow tube 02 out of the heat treatment furnace and quickly put it into the lower mold of the mold;

[0119] (7) Start the hydraulic equipment to close the upper mold (first positioning plate 1112 and first bending plate 1211) and the lower mold (second positioning plate 1121 and second bending plate 1221) of the forming mold 01 and maintain pressure. For the hollow tube 02 with a wall thickness of 10mm~20mm, apply 100 tons of pressure; for the hollow tube 02 with a wall thickness of 5mm~10mm, apply 50 tons of pressure. When the temperature of the hollow tube 02 drops to 500℃, first manually open the anti-unhooking hook, then control the hydraulic equipment to separate the forming mold 01 and take out the hollow tube 02;

[0120] (8) For hollow tubes 02 with a wall thickness of 5 mm to 10 mm, prepare a nitric acid solution with a mass fraction of 25% to 40%; for hollow tubes 02 with a wall thickness of 10 mm to 20 mm, prepare a mixed solution of hydrochloric acid with a mass fraction of 20% to 25% + nitric acid with a mass fraction of 3% to 5%;

[0121] (9) Soak the hollow tube 02 in a nitric acid solution (volatile corrosive gases are generated during the dissolution process, so the operation needs to be carried out in a site with safety protection and exhaust measures; operators should wear safety protection equipment; the discharge of hazardous waste products should comply with safety and environmental protection requirements). After the support shaft 31 in the hollow tube 02 is dissolved and disappears, take out the hollow tube 02, and rinse the acid solution on the surface of the hollow tube 02 with clean water to obtain a hollow elbow.

[0122] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made thereto in form and detail without departing from the scope of the present disclosure.

Claims

1. A hollow tube bending system, characterized in that: include: Forming dies, support dies and hollow tubes; The forming die has an extrusion channel, the extrusion channel includes a straight channel and a bending channel, and the straight channel is connected to the bending channel; The hollow tube includes a first tube and a second tube, the first tube is fixedly connected to the second tube, and the first tube is communicated with the second tube; the hollow tube bending system has a forming state, the forming state includes the first tube being located in the straight channel, the outer peripheral surface of the first tube abutting against the straight channel, the second tube being in a bent state and located in the bending channel, and the outer peripheral surface of the second tube abutting against the bending channel; The supporting mold includes a supporting shaft and a thread groove assembly, the thread groove assembly is arranged on the outer circumferential surface of the supporting shaft, the thread groove assembly includes a first section of spiral groove, a second section of spiral groove, a third section of spiral groove and a fourth section of spiral groove which are spirally arranged on the outer circumferential surface of the supporting shaft in sequence, the four sections of spiral grooves are connected to each other, both ends of the supporting shaft have spiral groove openings connected to the four sections of spiral grooves, the supporting shaft is located inside the hollow tube, the outer circumferential surface of the supporting shaft abuts against the hollow tube, the first section of spiral groove, the second section of spiral groove and the third section of spiral groove are located in the bending channel, the fourth section of spiral groove is located in the straight channel, according to the depth and / or width of the four sections of spiral grooves, the depth of the first section of spiral groove is less than the depth of the third section of spiral groove < the depth of the second section of spiral groove < the depth of the fourth section of spiral groove, and / or the width of the first section of spiral groove is less than the width of the third section of spiral groove < the width of the second section of spiral groove < the width of the fourth section of spiral groove.

2. A hollow tube bending system according to claim 1, characterized in that: The side wall of the spiral groove is an inclined surface, a tooth surface or an inclined surface with a tooth surface.

3. A hollow tube bending system according to claim 1, characterized in that: The forming die comprises a positioning assembly and a bending assembly, wherein the positioning assembly and the bending assembly are arranged side by side; The positioning assembly includes an upper positioning unit and a lower positioning unit, the upper positioning unit is arranged opposite to the lower positioning unit; the upper positioning unit includes a first positioning plate and a first positioning groove, the first positioning groove is arranged at the bottom of the first positioning plate; the lower positioning unit includes a second positioning plate and a second positioning groove, the second positioning groove is arranged at the top of the second positioning plate, the first positioning groove corresponds to the second positioning groove, and the first positioning groove and the second positioning groove constitute the linear channel; The bending assembly includes an upper bending unit and a lower bending unit, and the upper bending unit is arranged opposite to the lower bending unit; the upper bending unit includes a first bending plate and a first bending groove, and the first bending groove is arranged at the bottom of the first bending plate; the lower bending unit includes a second bending plate and a second bending groove, and the second bending groove is arranged at the top of the second bending plate, the first bending groove corresponds to the second bending groove, and the first bending groove and the second bending groove constitute the bending channel; the first bending groove extends in a direction away from the positioning assembly and bends in a direction close to the second bending plate, and the bending direction of the second bending groove is consistent with the bending direction of the first bending groove; the first bending groove and the first positioning groove have the same axis of symmetry, and the second bending groove and the second positioning groove have the same axis of symmetry.

4. A hollow tube bending system according to claim 3, characterized in that: The first tube has a first force-bearing portion, a second force-bearing portion and a third force-bearing portion, the first force-bearing portion corresponds to the first section of the spiral groove, the second force-bearing portion corresponds to the second section of the spiral groove, and the third force-bearing portion corresponds to the third section of the spiral groove; The second tube has a fourth force-bearing portion, and the fourth force-bearing portion is arranged opposite to the fourth section of the spiral groove; the force relationship of the four force-bearing portions is: the first force-bearing portion> the third force-bearing portion> the second force-bearing portion> the fourth force-bearing portion; The first bending groove has a first pressure portion, a second pressure portion and a third pressure portion, the first pressure portion corresponds to the first force-bearing portion, the second pressure portion corresponds to the second force-bearing portion, and the third pressure portion corresponds to the third force-bearing portion; the first positioning groove is provided with a fourth pressure portion, and the fourth pressure portion is arranged opposite to the fourth force-bearing portion; the pressure relationship of the four pressure portions is: first pressure portion>third pressure portion>second pressure portion>fourth pressure portion.

5. A hollow tube bending system according to claim 3, characterized in that: The upper positioning unit also includes a third positioning plate and a pre-tightening member; The preload member comprises a first guide shaft, a spring and a first guide hole, wherein the first guide hole is arranged on the first positioning plate, the spring is sleeved on the first guide shaft, one end of the first guide shaft is fixedly connected to the third positioning plate, the other end of the first guide shaft is connected to the first guide hole, the first guide hole is provided with a clamping portion, and the first guide shaft is provided with a clamping block clamped with the clamping portion; The forming state includes that the first positioning plate and the third positioning plate are in contact with each other, the spring is in a compressed state and is located in the first guide hole, and there is a gap between the clamping block and the clamping portion.

6. A hollow tube bending system according to claim 3, characterized in that: The positioning assembly also includes a locking unit; The locking unit includes a locking hook and a locking protrusion, the locking hook is rotatably connected to the first positioning plate, the locking protrusion is fixedly connected to the second positioning plate, and the formed state includes the locking hook and the locking protrusion being clamped together.

7. A hollow tube bending system according to claim 6, characterized in that: The locking hook has a first abutting surface that is engaged with the locking protrusion, the first abutting surface is provided with a groove, and the end of the locking protrusion has an arc surface that can be in sliding contact with the groove.

8. The hollow tube bending system according to claim 3, characterized in that: The forming die also includes a condensation assembly; The condensation assembly includes a first condensation tube, a second condensation tube and a third condensation tube. The first positioning plate is provided with a first condensation groove for accommodating the first condensation tube, the first bending plate is provided with a second condensation groove for accommodating the second condensation tube, and the second positioning plate and the second bending plate are provided with a third condensation groove for accommodating the third condensation tube.

9. The hollow tube bending system according to claim 1, characterized in that: The support shaft is provided with a hollow channel, and the hollow channel can be communicated with the four sections of the spiral grooves.

10. A bending method applied to the hollow tube bending system as claimed in claim 5, characterized in that: The bending method comprises the following steps: heating the hollow tube until the temperature of the hollow tube is a first temperature, and inserting a support shaft into the hollow tube; The foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the second folding plate, and the foldable plate is adapted to move toward the The hollow tube is maintained in a state of forming a second tube until the first temperature drops to a second temperature, and the hollow tube is immersed in a dissolving liquid, the dissolving liquid flows into the spiral groove on the support shaft, and the dissolving liquid dissolves the support shaft to obtain a bent tube.

11. The bending method according to claim 10, characterized in that: In the process of the driving assembly driving the first bending plate and the third positioning plate to move, the hollow tube bending system has a hollow tube installation state, an unformed state and a formed state that change in sequence; The hollow tube installation state includes one end of the hollow tube being located on the second positioning groove, the other end of the hollow tube being suspended between the first bending groove and the second bending groove, and there being a distance between the first positioning plate and the third positioning plate; The unformed state includes the first positioning groove abutting against the outer peripheral surface of the hollow tube based on the installed hollow tube state, the distance between the first positioning plate and the third positioning plate remains unchanged or becomes smaller, and the first pressure part of the first bending groove abuts against or does not abut against the outer peripheral surface of the hollow tube; the formed state includes the first bending groove and the second bending groove abutting against the outer peripheral surface of the hollow tube based on the unformed state, the first positioning plate abuts against the third positioning plate, and the second tube is formed at one end of the hollow tube.

12. The bending method according to claim 11, characterized in that: In the process from the unformed state to the formed state, the hollow tube bending system has a first extrusion state, a second extrusion state and a third extrusion state that change in sequence. The first extrusion state includes the first pressure portion abutting or not abutting against the outer circumferential surface of the hollow tube, and the fourth pressure portion of the first positioning groove abutting against the outer circumferential surface of the hollow tube; based on the first extrusion state, the second extrusion state includes the first pressure portion abutting against the outer circumferential surface of the hollow tube, and the second pressure portion of the first bending groove abutting against the outer circumferential surface of the hollow tube; the third extrusion state includes the third pressure portion of the first bending groove abutting against the outer circumferential wall of the hollow tube based on the second extrusion state.

13. The bending method according to claim 10, characterized in that: The hollow tube is made of titanium alloy, the support shaft is made of low carbon steel, and the dissolving solution includes 25% to 40% nitric acid solution, or a mixed solution of 20% to 25% hydrochloric acid and +3% to 5% nitric acid, by mass fraction.

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