Press bending apparatus and forming method
By heating the inner side of the tube blank and cooling the outer side in the pressure bending forming device to create a temperature difference state, the problem of thinning on the outer side of the tube is solved, the bending strength and wall thickness uniformity of the tube are improved, and the efficiency and accuracy of pressure bending forming are enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANCHANG HANGKONG UNIVERSITY
- Filing Date
- 2024-03-15
- Publication Date
- 2026-07-31
AI Technical Summary
Existing bending processes can easily lead to significant thinning of the outer side of the pipe, and even cause cracks in the outer wall and internal wrinkles, affecting the reliability and safety of the pipe.
A bending forming device is used to heat the inner side of the tube blank with a heating component to improve its plasticity, and to cool the outer side with a cooling component to create a temperature difference state, which reduces the flow of material on the outer side, resists tensile stress, and hinders the reduction of wall thickness.
It improves the strength and wall thickness uniformity of the outer side of the pipe bending, reduces the outer thinning amount, and improves the efficiency and precision of pressure bending.
Smart Images
Figure CN118080633B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of pipe bending forming, and particularly to a bending forming apparatus and its forming method. Background Technology
[0002] In modern aviation, aerospace, and automotive industries, to achieve weight reduction and save usable space, most tubular components are manufactured using integral molding technology. Typically, when a tube is bent, the outer side is thinned by tensile force, while the inner side thickens by compressive force. Therefore, there is always a difference in wall thickness between the inner and outer walls of a bent tube. In particular, the thinning of the outer wall caused by bending has a significant impact on the reliability and safety of the tube in its later use. Therefore, various bending processes aim to minimize the thinning of the outer wall of the tube to avoid excessive thickness loss. Among existing tube bending processes, pressure bending is a common method. During pressure bending, the tube is subjected to external force, causing the lower part of the tube to bend under tensile force, resulting in thinning of the outer wall. Meanwhile, the internal pressure of the tube also causes bending deformation, resulting in thickening of the inner wall. This is especially true for some special parts. For these types of tubes, conventional pressure bending methods can easily cause significant thinning of the outer wall, and even lead to cracking of the outer wall and internal wrinkling. Summary of the Invention
[0003] Therefore, it is necessary to provide a bending forming device and its forming method to solve the problem that conventional bending methods can easily cause significant thinning of the outer side of the pipe, or even cracking of the outer wall and wrinkling of the inside.
[0004] A bending forming apparatus, comprising:
[0005] A bending die includes a concave die and a convex die, the shapes of which are adapted to each other. The concave die and the convex die are arranged opposite to each other, with the convex die located above the concave die. A tube blank is placed between the convex die and the concave die, and the concave die and the convex die cooperate to bend the tube blank to obtain a bent tube.
[0006] The differential temperature assembly includes a heating assembly and a cooling assembly. The heating assembly is disposed on the convex mold and is used to heat the inner side of the tube blank to improve the plasticity of the tube blank. The cooling assembly is disposed on the concave mold and is used to cool the outer side of the tube blank to improve the strength of the outer side of the tube blank.
[0007] Optionally, the concave mold includes a concave mold portion and a first cavity, the first cavity being formed on the top surface of the concave mold, the tube blank being placed in the first cavity, and the convex mold being able to move in a direction toward the concave mold so that the convex mold and the tube blank come into contact and the tube blank is bent and deformed.
[0008] Optionally, the convex mold includes a punch and a protrusion. The protrusion is disposed at the bottom end of the punch. The punch and the protrusion have a second cavity on their sides. The tube blank is placed in the second cavity. The bottom end of the protrusion is used to contact the tube blank and to bend the tube blank along the second cavity.
[0009] Optionally, the heating assembly includes a heating element and a first thermocouple. The heating element is disposed on the punch portion and is used to heat the punch mold, thereby heating the inner side of the tube blank. The first thermocouple is disposed on the punch mold and is used to detect the temperature of the punch mold.
[0010] Optionally, the cooling assembly includes a cooling tank and a second thermocouple. The cooling tank is disposed in the concave mold portion and is used to introduce a cooling medium to cool the concave mold, thereby cooling the bent outer side of the tube blank. The second thermocouple is disposed in the concave mold portion and is used to detect the temperature of the concave mold.
[0011] Optionally, it may also include a first support component and a second support component, which are respectively disposed at both ends of the tube blank to support the tube blank.
[0012] Optionally, the first support assembly includes a first support base and a first bracket, the first bracket being disposed at one end of the tube blank, and the first bracket being rotatably connected to the first support base to provide support for one end of the tube blank.
[0013] Optionally, the second support assembly includes a second support base and a second bracket. The second support base is disposed at the other end of the tube blank, and the second bracket is rotatably connected to the second support base to provide support for the other end of the tube blank.
[0014] Optionally, it may also include a support filler, which is filled and disposed inside the tube blank and is used to support the interior of the tube blank.
[0015] A bending forming method, the method using the above-mentioned apparatus, the method comprising the following steps:
[0016] The electric heating component heats the convex mold to a preset temperature, while the cooling medium is injected into the cooling tank. The flow of the cooling medium carries away the heat inside the concave mold, thereby reducing the temperature outside the concave mold. This increases the strength of the tube blank material, reduces the flow of tube blank material when the outer side is bent, and resists the tensile stress during the tube blank forming process, thus hindering the thinning of the wall thickness on the outer side of the tube blank when bent.
[0017] The middle part of the tube blank is placed in the first cavity and the second cavity. The two ends of the tube blank are fixedly connected to the first support and the second support, respectively. When the convex mold reaches the set pressure, the convex mold and the concave mold slowly drive the tube blank to move downward. During the movement of the tube blank, the first support rotates relative to the first support seat, and the second support rotates relative to the second support seat, so that the first support and the second support provide support force to the two ends of the tube blank, respectively. Finally, the tube blank is bent into shape to obtain a bent tube.
[0018] The bending forming apparatus provided in this application heats the inner side of the tube blank by providing a heating component in the convex mold, thereby increasing the forming temperature of the inner side of the tube blank, which improves the plasticity of the tube blank, reduces the deformation resistance, promotes the uniform flow of its own material during the forming process in the convex mold, slows down the thickening caused by material accumulation, and improves the bendability of the tube blank, making the tube blank easier to bend. Furthermore, a cooling component is provided in the concave mold to reduce the temperature of the outer side of the concave mold, thereby reducing the temperature of the outer side of the tube blank, increasing the strength of the tube blank material on the outer side of the bend, reducing the flow of its own material on the outer side of the bend during deformation, and thus resisting the tensile stress on the outer side of the tube blank during the forming process, hindering the thinning of the outer wall thickness of the tube blank, and thus reducing the amount of thinning of the outer wall thickness of the tube blank, thereby improving the wall thickness uniformity of the tube blank during bending forming and improving the efficiency of tube blank bending forming. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the bending process of the bending forming device in one embodiment;
[0021] Figure 2 This is a schematic diagram of the concave mold of the bending forming device in one embodiment;
[0022] Figure 3 This is a schematic diagram of the convex mold of the bending forming device in one embodiment;
[0023] Figure 4 This is a schematic diagram of the bending forming device in one embodiment.
[0024] 1. Bending die; 11. Concave die; 111. Concave die part; 112. First cavity; 12. Convex die; 121. Convex die part; 122. Protrusion; 123. Second cavity; 2. Tube blank; 3. Differential temperature assembly; 31. Heating assembly; 311. Heating element; 312. First thermocouple; 32. Cooling assembly; 321. Cooling tank; 322. Second thermocouple; 4. First support assembly; 41. First support base; 42. First bracket; 5. Second support assembly; 51. Second support base; 52. Second bracket; 6. Support filler.
[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.
[0028] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the term "and / or" throughout the text includes three solutions; taking A and / or B as an example, it includes technical solution A, technical solution B, and a technical solution that simultaneously satisfies A and B. Furthermore, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0029] refer to Figure 1 and Figure 4This application provides a bending forming apparatus and a forming method thereof. The bending forming apparatus includes a bending die 1 and a temperature differential assembly 3. The bending die 1 includes a concave die 11 and a convex die 12. The shapes of the concave die 11 and the convex die 12 are adapted to each other. The concave die 11 and the convex die 12 are arranged opposite to each other, and the convex die 12 is located above the concave die 11. The tube blank 2 is disposed between the convex die 12 and the concave die 11. The concave die 11 and the convex die 12 cooperate to bend the tube blank 2 to obtain a bent tube. The temperature differential assembly 3 includes a heating assembly 31 and a cooling assembly 32. The heating assembly 31 is disposed on the convex die 12 and is used to heat the inner side of the bent tube blank 2 to improve the material plasticity of the inner side of the bent tube blank 2. The cooling assembly 32 is disposed on the concave die 11 and is used to cool the outer side of the bent tube blank 2 to improve the material strength of the outer side of the bent tube blank 2.
[0030] The bending forming apparatus provided in this application heats the inner side of the tube blank 2 by providing a heating component 31 to the convex mold 12, thereby increasing the forming temperature of the inner side of the tube blank 2, which improves the plasticity of the tube blank 2, reduces the deformation resistance, promotes the uniform flow of its own material during the forming process in the convex mold, slows down the thickening caused by material accumulation, and improves the bendability of the tube blank, making the bending of the tube blank 2 easier. Furthermore, by providing a cooling component 32 to the concave mold 11, the temperature of the outer side of the concave mold 11 is reduced, thereby reducing the temperature of the outer side of the tube blank 2 during bending, which increases the strength of the tube blank material on the outer side of the tube blank 2 during deformation, thereby reducing the flow of its own material on the outer side of the tube blank 2 during forming, thus resisting the tensile stress on the outer side of the tube blank 2 during the forming process, hindering the thinning of the outer wall thickness of the outer side of the tube blank 2, thereby reducing the amount of thinning of the outer wall thickness of the outer side of the tube blank 2, thereby improving the uniformity of the wall thickness of the tube blank 2 during bending, and thus improving the efficiency of the bending forming of the tube blank 2.
[0031] Specifically, the material of tube blank 2 is cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel or non-ferrous metal.
[0032] refer to Figure 1 and Figure 2 The concave mold 11 includes a concave mold portion 111 and a first cavity 112. The first cavity 112 is formed on the top surface of the concave mold 11. The convex mold 12 can move in a direction toward the concave mold 11 so that the convex mold 12 and the tube blank 2 come into contact and the tube blank 2 is bent and deformed.
[0033] refer to Figure 3 and Figure 4The convex mold 12 includes a punch part 121 and a protrusion 122. The protrusion 122 is disposed at the bottom end of the punch part 121 and is semi-circular. The sides of the punch part 121 and the protrusion 122 are provided with a second cavity 123. The second cavity 123 is arc-shaped. The middle part of the tube blank 2 is placed in the mold cavity formed by the first cavity 112 and the second cavity 123. The bottom end of the protrusion 122 is used to contact the tube blank 2 and to bend the tube blank 2 along the second cavity 123.
[0034] Specifically, the shape and size of the second cavity 123 are selected according to the actual needs of bending the tube blank 2.
[0035] Specifically, the convex mold 12 is mounted on an external press. The press provides a preset pressure to the convex mold 12. The convex mold 12 can reciprocate in a direction away from or towards the concave mold 11 under the drive of the press. When the convex mold 12 and the concave mold 11 are closed, the second cavity 123 and the first cavity 112 are connected to form a mold cavity, which is used to accommodate the tube blank 2 to be processed.
[0036] The heating assembly 31 includes a heating element 311 and a first thermocouple 312. The heating element 311 is disposed on the punch portion 121 and is used to heat the punch mold 12, thereby heating the inner side of the tube blank 2. The first thermocouple 312 is disposed on the punch mold 12 and is used to detect the temperature of the punch mold 12.
[0037] Specifically, the heating element 311 is a heating rod, which is used to heat the outer side of the concave mold 11 to a preset temperature and control the temperature within ±2℃. The preset temperature is set according to the different forming materials, and the preset temperature is 200~400℃.
[0038] Specifically, the heating element 311 and the first thermocouple 312 are disposed inside the punch portion 121 along the axial direction of the punch portion 121. Furthermore, the heating element 311 and the first thermocouple 312 are arranged vertically at intervals. Furthermore, there are multiple heating elements 311 and multiple first thermocouples 312, with the first thermocouple 312 disposed between two heating elements 311.
[0039] The cooling assembly 32 includes a cooling tank 321 and a second thermocouple 322. The cooling tank 321 is disposed in the die portion 111 and is used to introduce a cooling medium to cool the die 11, thereby cooling the curved outer side of the tube blank 2. The second thermocouple 322 is disposed in the die portion 111 and is used to detect the temperature of the die 11.
[0040] Specifically, the cooling tank 321 has an inverted U-shaped structure to increase the cooling range. Furthermore, a length is reserved between the inlet of the cooling tank 321 and the bottom of the first cavity 112. Preferably, the inlet is located at the end of the die portion 111 furthest from the first cavity 112, i.e., the bottom end of the die portion 111, so that the tube blank 2 can be cooled to a lower forming temperature. The second thermocouple 322 is located below the cooling tank 321 and in the middle of the cooling tank 321. In this embodiment, the cooling medium is cooling water, and the initial temperature of the cooling water is room temperature.
[0041] In this embodiment, there are two cooling tanks 321 and two second thermocouples 322. The second thermocouples 322 are arranged one-to-one below the cooling tanks 321, and the two cooling tanks 321 are arranged opposite each other to improve cooling efficiency.
[0042] Specifically, by heating the outside of the convex mold 12 and cooling the outside of the concave mold 11, a temperature difference is formed. Depending on the forming material, the heating temperature is different, and the temperature difference between the inside and outside can reach 100 to 300°C.
[0043] The bending forming device of this application further includes a first support component 4 and a second support component 5. The first support component 4 and the second support component 5 are respectively disposed at both ends of the tube blank 2, so that during the bending forming process, the first support component 4 and the second support component 5 always provide an upward support force perpendicular to the axial direction of both ends of the tube blank 2 to the undeformed areas at both ends of the tube blank 2.
[0044] refer to Figure 1 The first support assembly 4 includes a first support base 41 and a first bracket 42. The first bracket 42 is disposed at one end of the tube blank 2 and is rotatably connected to the first support base 41 to provide upward support to one end of the tube blank 2 in an axial direction perpendicular to one end of the tube blank 2. The second support assembly 5 includes a second support base 51 and a second bracket 52. The second support base 51 is disposed at the other end of the tube blank 2, and the second bracket 52 is rotatably connected to the second support base 51 to provide upward support to the other end of the tube blank 2 in an axial direction perpendicular to one end of the tube blank 2.
[0045] Specifically, the first support base 41 and the second support base 51 are placed on the table, and the top surface of the first support base 41 is flush with the top surface of the second support base 51, and the top surface of the first support base 41 is flush with the bottom end of the tube blank 2.
[0046] During the bending process, the tube blank 2 is bent downwards and driven the first support 42 and the second support 52 to rotate in opposite directions. The rotation direction of the first support 42 is opposite to that of the second support 52.
[0047] A bending forming method, the method using the forming apparatus described above, the method comprising the following steps:
[0048] S1, blank 2 blanking and external coating of lubricant on blank 2;
[0049] Cut a tube blank 2 of length m, where m is much larger than πD. Clean the outside of the tube blank 2 thoroughly. Spray the inside of the tube blank 2 with a high-temperature resistant boron nitride lubricant to protect the surface of the tube blank 2 from scratches and prevent wrinkling.
[0050] S2. The heating component 31 is energized to heat the outer side of the convex mold. The heating temperature is set to 200-400℃. The heat from the outer side of the convex mold 12 is transferred to the inner side of the tube blank 2 during bending, thereby increasing the deformation temperature of the inner side of the tube blank 2 during the forming process. This increases the plasticity of the material on the inner side of the tube blank 2 during bending, thereby reducing the deformation resistance of the inner side of the tube blank 2. This promotes the uniform flow of the material of the tube blank 2 during the forming process in the convex mold, improves the bendability of the tube blank, and makes the tube blank 2 easier to bend. It also reduces springback and improves the bending forming accuracy. At the same time, the cooling tank 321 circulates a cooling medium to cool the outer side of the concave mold. The initial temperature of the cooling medium is room temperature. The flow of the cooling medium carries away the heat from the inner side of the concave mold 11, thereby reducing the temperature of the outer side of the concave mold 11. This increases the strength of the material of the tube blank 2, reduces the flow of the tube blank material during the deformation of the outer side of the bend, and thus resists the tensile stress on the tube blank 2 during the forming process. This hinders the thinning of the wall thickness on the outer side of the tube blank during bending, thereby improving the overall wall thickness uniformity of the bent tube.
[0051] S3. The middle part of the tube blank 2 is placed in the first cavity 112 and the second cavity. The two ends of the tube blank 2 are fixedly connected to the first support 42 and the second support 52 respectively. The convex mold 12 and the concave mold 11 fix the middle part of the tube blank from the top and bottom. When the convex mold 12 reaches the set pressure, the convex mold 12 and the concave mold 11 slowly drive the tube blank 2 to move downward. During the movement of the tube blank 2, the first support 42 rotates relative to the first support seat 41, and the second support 52 rotates relative to the second support seat 51, so that the first support 42 and the second support 52 provide support force for the two ends of the tube blank 2 respectively. Finally, it is bent into shape to obtain a bent tube.
[0052] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.
Claims
1. A bending forming method, characterized in that, The method uses a bending forming device, the bending forming device comprising: A bending die includes a concave die and a convex die, the shapes of which are adapted to each other. The concave die and the convex die are arranged opposite to each other, with the convex die located above the concave die. A tube blank is placed between the convex die and the concave die, and the concave die and the convex die cooperate to bend the tube blank to obtain a bent tube. A differential temperature assembly includes a heating assembly and a cooling assembly. The heating assembly is disposed on the convex mold and is used to heat the inner side of the tube blank to improve the plasticity of the tube blank. The cooling assembly is disposed on the concave mold and is used to cool the outer side of the tube blank to improve the strength of the outer side of the tube blank. The method includes the following steps: The electric heating component heats the convex mold to a preset temperature, while the cooling medium is injected into the cooling tank. The flow of the cooling medium carries away the heat inside the concave mold, thereby reducing the temperature outside the concave mold. This increases the strength of the tube blank material, reduces the flow of tube blank material when the outer side is bent, and resists the tensile stress during the tube blank forming process, thus hindering the thinning of the wall thickness on the outer side of the tube blank when bent. The middle part of the tube blank is placed in the first cavity and the second cavity. The two ends of the tube blank are fixedly connected to the first support and the second support, respectively. When the convex mold reaches the set pressure, the convex mold and the concave mold slowly drive the tube blank to move downward. During the movement of the tube blank, the first support rotates relative to the first support seat, and the second support rotates relative to the second support seat, so that the first support and the second support provide support force to the two ends of the tube blank, respectively. Finally, the tube blank is bent into shape to obtain a bent tube.
2. The bending forming method according to claim 1, characterized in that, The concave mold includes a concave mold portion and a first cavity. The first cavity is formed on the top surface of the concave mold. The tube blank portion is placed in the first cavity. The convex mold can move in a direction toward the concave mold so that the convex mold and the tube blank come into contact and the tube blank is bent and deformed.
3. The bending forming method according to claim 2, characterized in that, The convex mold includes a punch and a protrusion. The protrusion is disposed at the bottom end of the punch. The punch and the protrusion have a second cavity on their sides. The tube blank is placed in the second cavity. The bottom end of the protrusion is used to contact the tube blank and bend the tube blank along the second cavity.
4. The bending forming method according to claim 3, characterized in that, The heating assembly includes a heating element and a first thermocouple. The heating element is disposed on the punch portion and is used to heat the punch mold, thereby heating the inner side of the tube blank. The first thermocouple is disposed on the punch mold and is used to detect the temperature of the punch mold.
5. The bending forming method according to claim 2, characterized in that, The cooling assembly includes a cooling tank and a second thermocouple. The cooling tank is disposed in the concave mold portion and is used to introduce a cooling medium to cool the concave mold, thereby cooling the bent outer side of the tube blank. The second thermocouple is disposed in the concave mold portion and is used to detect the temperature of the concave mold.
6. The bending forming method according to claim 1, characterized in that, The bending forming device further includes a first support component and a second support component, which are respectively disposed at both ends of the tube blank to support the tube blank.
7. The bending forming method according to claim 6, characterized in that, The first support assembly includes a first support base and a first bracket. The first bracket is disposed at one end of the tube blank and is also rotatably connected to the first support base to provide support for one end of the tube blank.
8. The bending forming method according to claim 7, characterized in that, The second support assembly includes a second support base and a second bracket. The second support base is disposed at the other end of the tube blank, and the second bracket is rotatably connected to the second support base to provide support for the other end of the tube blank.
9. The bending forming method according to claim 1, characterized in that, The bending forming device further includes a support filler, which is filled inside the tube blank and is used to support the inside of the tube blank.