Forming die, equipment and forming method for large-caliber thick-wall elbow

Abstract

The present invention provides a forming die, equipment and forming method for a large-diameter thick-wall bent pipe, belonging to the technical field of bent pipe equipment, including an upper die, a lower die and an inner die core; the upper die and the lower die can be buckled with each other; the buckling surfaces of the upper die and the lower die both have a material placing groove and a bending groove that communicate with each other; the inner die core can be placed in the bending groove between the upper die and the lower die; the inner die core is used for plugging and matching with the pipe fitting, and there is a space for the pipe fitting to pass between the outer peripheral wall of the inner die core and the inner peripheral wall of the bending groove; wherein, a plurality of first avoidance grooves are provided in the bending groove; a set of bending section auxiliary roller groups are arranged in each first avoidance groove; by arranging the bending section auxiliary roller groups in the upper die and the lower die, the combined use of the inner and outer dies and the roller groups can be realized, the plastic deformation resistance of the pipe fitting during the bending process can be reduced, and further the situation of forming defects can be reduced, and the yield and product quality can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipe bending equipment, and particularly relates to a forming die, equipment and forming method for large-diameter thick-wall pipes. Background Art

[0002] The bending process refers to a manufacturing process in which an external force is applied to a material to cause plastic deformation or elastic deformation, so that the material is bent along a specific curve shape.

[0003] During the bending process of tubular parts, due to the complex and unbalanced tensile and compressive stresses distributed on the inner and outer sides of the pipe fittings, when the pipe is bent and formed, the outer material is subjected to tangential tensile stress and the wall thickness is reduced, while the inner material is subjected to tangential compressive stress and the wall thickness is increased. Among them, the materials at the outermost and innermost sides of the bending deformation zone are subjected to the largest absolute value of tangential stress, so their wall thickness changes are also the largest, and various defects such as pipe wall wrinkles, excessive wall thickness reduction, pipe cross-section distortion, and pipe fitting unloading springback are likely to occur; this is particularly obvious in the bending forming of large-diameter pipe fittings and thick-wall pipe fittings.

[0004] The tensile and compressive stresses distributed on the inner and outer sides of the pipe fittings mainly come from the friction between the rigid outer die and the pipe fittings. This is because in traditional rigid pipe bending dies, the bending part of the die is a fixed rigid body. When the pipe fitting flows through here during the deformation process, bending deformation and contact sliding friction occur; the bending action of the bending part of the die hardens the material and increases the deformation resistance of the material. The sliding friction is opposite to the direction of plastic flow and also plays a role in hindering deformation.

[0005] Therefore, traditional pipe bending processes often use internal lubrication in the die or use materials with a small coefficient of friction to make the die, in order to reduce the friction suffered by the pipe fitting during bending forming, and thus improve the forming quality of the bent pipe fitting; however, this method does not change the friction action mode of the rigid pipe bending die itself on the pipe fitting, so the traditional pipe bending process has little effect when applied to large-diameter thick-wall pipe fittings with greater frictional resistance and material deformation resistance. Summary of the Invention

[0006] The embodiments of the present invention provide a forming die, equipment and forming method for large-diameter thick-wall pipes, aiming to solve the problem that the pipe bending process in the prior art is prone to cause defects in large-diameter thick-wall pipe fittings during bending forming.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] Provide a forming die for large-diameter thick-wall pipes, including:

[0009] An upper die and a lower die that can be buckled with each other; the buckling surfaces of the upper die and the lower die both have a material feeding groove and a bending groove that communicate with each other;

[0010] The inner mold core can be placed in the bending groove between the upper mold and the lower mold; the inner mold core is used to be plugged with the pipe fitting, and there is a space for the pipe fitting to pass between the outer peripheral wall of the inner mold core and the inner peripheral wall of the bending groove;

[0011] Among them, the inner wall of the bending groove is provided with a plurality of first avoidance grooves along the bending direction, and each of the first avoidance grooves is arranged along the radial direction of the bending groove; each of the first avoidance grooves is provided with a group of bending section auxiliary roller groups, and each group of bending section auxiliary roller groups is rotatably arranged in the corresponding bending groove, and each group of bending section auxiliary roller groups is rotatably matched with the outer wall of the pipe fitting.

[0012] In a possible implementation, each group of the bending section auxiliary roller group includes a large roller, a second large roller, a middle roller, a second small roller and a small roller, and the large roller, the second large roller, the middle roller, the second small roller and the small roller are all tangent to the outer peripheral wall of the pipe;

[0013] Among them, the small roller contacts the position of the pipe fitting with the smallest bending radius, and the large roller contacts the position of the pipe fitting with the largest bending radius.

[0014] In a possible implementation, the outer peripheral walls of the large roller, the second large roller, the middle roller, the second small roller and the small roller are all concave surfaces in contact with the outer peripheral wall of the pipe.

[0015] In a possible implementation, a second avoidance groove is provided at the connection position of the discharge groove and the bending groove, and a straight wall section auxiliary roller group is provided in the second avoidance groove. The straight wall section auxiliary roller group includes a plurality of auxiliary rollers, and each auxiliary roller is rotatably arranged in the second avoidance groove.

[0016] In a possible implementation, the number of auxiliary rollers is 5, the size of each auxiliary roller is the same, and the outer peripheral wall of each auxiliary roller is a concave surface in contact with the outer peripheral wall of the pipe.

[0017] In a possible implementation, the position of each roller facing the pipe is the inner side, and the position away from the pipe is the outer side; the ends of two adjacent rollers contact each other near the inner side, so that the concave surface of the roller forms a complete circumferential surface.

[0018] The large-diameter thick-walled bending pipe forming die provided by the present invention, compared with the prior art, can realize the coordinated use of inner and outer dies and roller groups by arranging bending section auxiliary roller groups in the upper die and the lower die, thereby reducing the plastic deformation resistance of the pipe during the bending process, thereby reducing the occurrence of forming defects and improving the yield rate and product quality.

[0019] To achieve the above object, another technical solution adopted by the present invention is:

[0020] Provide a large-diameter thick-wall elbow forming device, including a frame and the above-mentioned forming die, and the lower die is fixed on the ground; a die-closing hydraulic cylinder is provided on the frame, and the piston rod of the die-closing hydraulic cylinder is connected to the upper die;

[0021] A pushing hydraulic cylinder is further provided on the frame, and a punch is connected to the piston rod of the pushing hydraulic cylinder, and the punch is used to push the pipe fitting in the feeding groove;

[0022] A turning platform is provided on one side of the frame, and one end of the inner die core is connected to the turning platform.

[0023] The beneficial effects of the forming device provided by the present invention are the same as those of the forming die, and will not be elaborated here.

[0024] To achieve the above object, another technical solution adopted by the present invention is:

[0025] Provide a forming method applying the above-mentioned forming die, including the following steps:

[0026] Place the pipe fitting in the feeding groove of the lower die, and close the upper die and the lower die to circumferentially limit the pipe fitting;

[0027] The punch slides in the feeding groove to push the pipe fitting in the feeding groove; the pipe fitting is inserted and matched with the inner die core under the pushing action of the punch, and the outer peripheral wall of the pipe fitting rotates and cooperates with the bending section auxiliary roller group;

[0028] When the punch pushes in place, the pipe fitting is formed;

[0029] The upper die resets upward, the inner die core drives the pipe fitting to turn out of the feeding groove, and the bent and formed pipe fitting is separated from the inner die core.

[0030] The beneficial effects of the forming method provided by the present invention are the same as those of the forming die, and will not be elaborated here. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of a large-diameter thick-wall elbow forming die provided by an embodiment of the present invention;

[0032] Figure 2 It is a cross-sectional view of a large-diameter thick-wall elbow forming die provided by an embodiment of the present invention;

[0033] Figure 3 For Figure 2 The schematic diagram of part A-A in

[0034] Figure 4 For Figure 2 The schematic diagram of part B-B in

[0035] Description of reference numerals: 1. Upper die; 2. Auxiliary roller group for bending section; 2-1. Large roller; 2-2. Second large roller; 2-3. Medium roller; 2-4. Second small roller; 2-5. Small roller; 3. Inner die core; 4. Lower die; 5. Auxiliary roller group for straight wall section; 51. Auxiliary roller; 6. Pipe fitting; 7. Punch. Detailed implementation manners

[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Please refer to Figures 1 to 4 , and now a forming die and a forming method for a large-diameter thick-wall bent pipe provided by the present invention will be described. The forming die for a large-diameter thick-wall bent pipe includes an upper die 1, a lower die 4 and an inner die core 3; the upper die 1 and the lower die 4 can be buckled with each other; the buckling surfaces of the upper die 1 and the lower die 4 both have a material feeding groove and a bending groove that communicate with each other; the inner die core 3 can be placed in the bending groove between the upper die 1 and the lower die 4; the inner die core 3 is used for plugging and matching with the pipe fitting 6, and there is a space for the pipe fitting 6 to pass between the outer peripheral wall of the inner die core 3 and the inner peripheral wall of the bending groove; wherein, a plurality of first avoidance grooves are arranged along the bending direction on the inner peripheral wall of the bending groove, and each first avoidance groove is arranged along the radial direction of the bending groove; a set of auxiliary roller groups 2 for the bending section is arranged in each first avoidance groove, and each set of auxiliary roller groups 2 for the bending section is rotatably arranged in the corresponding bending groove, and each set of auxiliary roller groups 2 for the bending section is rotatably matched with the outer peripheral wall of the pipe fitting 6.

[0038] Compared with the prior art, the forming die for a large-diameter thick-wall bent pipe provided by the present invention can realize the combined use of the inner and outer dies and the roller groups by arranging the auxiliary roller groups 2 for the bending section in the upper die 1 and the lower die 4, reduce the plastic deformation resistance of the pipe fitting 6 during the bending process, and further reduce the occurrence of forming defects, thereby improving the yield and product quality.

[0039] In some embodiments, such as Figures 1 to 4As shown, each group of auxiliary rollers 2 of the bending section includes a large roller 2-1, a second large roller 2-2, a middle roller 2-3, a second small roller 2-4 and a small roller 2-5, and the diameters of the large roller 2-1, the second large roller 2-2, the middle roller 2-3, the second small roller 2-4 and the small roller 2-5 gradually decrease; the large roller 2-1, the second large roller 2-2, the middle roller 2-3, the second small roller 2-4 and the small roller 2-5 are all tangent to the outer peripheral wall of the pipe 6; wherein the small roller 2-5 contacts the position with the smallest bending radius of the pipe 6, and the large roller 2-1 contacts the bending radius of the pipe 6 The position with the largest radius is in contact, the second largest roller 2-2, the middle roller 2-3 and the second smallest roller 2-4 are located between the large roller 2-1 and the small roller 2-5, and the roller diameter increases with the increase of the bending radius; the outer peripheral walls of the large roller 2-1, the second largest roller 2-2, the middle roller 2-3, the second smallest roller 2-4 and the small roller 2-5 are all concave surfaces in contact with the outer peripheral wall of the pipe fitting 6; the position of each roller facing the pipe fitting 6 is the inner side, and the position away from the pipe fitting 6 is the outer side; the ends of two adjacent rollers are in contact with each other near the inner side, so that the concave surfaces of the rollers form a complete circular surface.

[0040] It should be noted that the sizes of the rollers in the bending section are inconsistent. The size of each roller in the bending section is calculated based on the bending radius of the pipe 6, so that the materials at different bending positions of the pipe 6 are at equal bending angular velocities, thereby reducing the cross-sectional distortion during bending deformation, reducing the occurrence of forming defects, and effectively improving the forming quality of the bent pipe 6.

[0041] Exemplarily, this embodiment is explained by taking five rollers as an example, that is, each first avoidance groove of the upper mold 1 has five rollers, and the corresponding position of the lower mold 4 also has five rollers; through the cooperation of ten rollers, the concave surface of the roller can form a complete circular surface; therefore, when the pipe fitting 6 passes through the position of the auxiliary roller group 2 of the bending section, the positions of different bending radii on the pipe fitting 6 contact with the corresponding rollers, which can improve the problem of inconsistent bending angular velocity of the material at different bending radius positions on the pipe fitting 6, reduce the occurrence of defects in the pipe fitting 6, and improve the forming quality of the pipe fitting 6.

[0042] Through the above-mentioned arrangement of the present application, during the bending process of the pipe 6, the rollers in the same first avoidance groove have the same angular velocity, ensuring that the points on each cross section of the pipe 6 have the same angular velocity of bending deformation, so that the bending deformation is carried out stably and the occurrence of deformation defects is reduced.

[0043] In addition, by setting a bending section auxiliary roller group 2 in the mold, the part of the pipe fitting 6 that is subject to a large deformation resistance during the forming process of the pipe fitting 6 is converted into rolling friction, thereby reducing the deformation resistance; at the same time, the diameters of each roller in the bending section auxiliary roller group 2 are designed according to the process parameters of the bending pipe fitting 6. Therefore, the present application can design corresponding models of bending section auxiliary roller groups 2 for thick-walled pipe fittings 6 of different calibers and different materials, and can adapt to the bending and forming of thick-walled pipe fittings 6 of different calibers and different materials; by setting up multiple groups of bending section auxiliary roller groups 2, the friction resistance of the pipe fitting 6 can be reduced while improving the processing quality of the pipe fitting 6.

[0044] In some embodiments, Figures 1 to 4 As shown, a second avoidance groove is provided at the connection position of the discharge groove and the bending groove, and a straight wall section auxiliary roller group 5 is provided in the second avoidance groove. The straight wall section auxiliary roller group 5 includes a plurality of auxiliary rollers 51, and each auxiliary roller 51 is rotatably arranged in the second avoidance groove; the number of auxiliary rollers 51 is 5, and the size of each auxiliary roller 51 is the same, and the outer peripheral wall of each auxiliary roller 51 is a concave surface in contact with the outer peripheral wall of the pipe fitting 6; the position of each roller facing the pipe fitting 6 is the inner side, and the position away from the pipe fitting 6 is the outer side; the ends of two adjacent rollers are in contact with each other near the inner side, so that the concave surface of the roller forms a complete circumferential surface. The size of the auxiliary roller 51 is the same as that of the small rollers 2-5.

[0045] It should be noted that since the second avoidance groove is located at the connecting position of the discharge groove and the bending groove, the pipe fitting 6 has not yet undergone bending deformation, so the sizes of the auxiliary rollers 51 here are the same; by arranging a straight-wall section auxiliary roller group 5 at this location, the sliding friction between the pipe fitting 6 and the bending groove can be converted into rolling friction, thereby improving the friction state, thereby reducing friction, reducing deformation resistance, and solving the problem that large-diameter thick-walled pipe fittings 6 are difficult to form.

[0046] Based on the same inventive concept, the present application also provides a large-diameter thick-walled bending pipe forming equipment, including a frame and the above-mentioned forming mold, the lower mold 4 is fixed on the ground; the frame is provided with a mold closing hydraulic cylinder, the piston rod of the mold closing hydraulic cylinder is connected to the upper mold 1; the frame is also provided with a pushing hydraulic cylinder, the piston rod of the pushing hydraulic cylinder is connected to a punch 7, the punch 7 is used to push the pipe fitting 6 in the discharge trough; a turning platform is provided on one side of the frame, and one end of the inner mold core 3 is connected to the turning platform; it should be noted that the turning platform is a prior art and will not be repeated here.

[0047] Based on the same inventive concept, the present application also provides a molding method using the above-mentioned molding die, comprising the following steps:

[0048] Place the pipe fitting 6 in the feeding groove of the lower die 4, and close the upper die 1 and the lower die 4 to circumferentially limit the pipe fitting 6; the punch 7 slides in the feeding groove to push the pipe fitting 6 in the feeding groove; the pipe fitting 6 is inserted and matched with the inner die core 3 under the pushing action of the punch 7, and the outer peripheral wall of the pipe fitting 6 rotates and cooperates with the bending section auxiliary roller set 2; when the punch 7 is pushed in place, the pipe fitting 6 is formed; the upper die 1 resets upward, the inner die core 3 drives the pipe fitting 6 to turn out of the feeding groove, and the bent pipe fitting 6 is separated from the inner die core 3. It should be noted that the process of the pipe fitting 6 separating from the inner die core 3 is the prior art and will not be elaborated here.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A large-caliber thick-walled bending pipe forming die, characterized in that: include: The upper mold and the lower mold can be buckled with each other; the buckling surfaces of the upper mold and the lower mold are both provided with a discharge groove and a bending groove which are interconnected; The inner mold core can be placed in the bending groove between the upper mold and the lower mold; the inner mold core is used to be plugged with the pipe fitting, and there is a space for the pipe fitting to pass between the outer peripheral wall of the inner mold core and the inner peripheral wall of the bending groove; The inner circumferential wall of the bending groove is provided with a plurality of first avoidance grooves along the bending direction, and each of the first avoidance grooves is arranged along the radial direction of the bending groove; each of the first avoidance grooves is provided with a group of bending section auxiliary roller groups, and each group of bending section auxiliary roller groups is rotatably arranged in the corresponding bending groove, and each group of bending section auxiliary roller groups is rotatably matched with the outer circumferential wall of the pipe fitting; Each group of the auxiliary rollers of the bending section includes a large roller, a second large roller, a middle roller, a second small roller and a small roller, and the large roller, the second large roller, the middle roller, the second small roller and the small roller are all tangent to the outer peripheral wall of the pipe; Among them, the small roller contacts the position of the pipe fitting with the smallest bending radius, and the large roller contacts the position of the pipe fitting with the largest bending radius.

2. A large-diameter thick-walled bending tube forming die as claimed in claim 1, characterized in that: The outer peripheral walls of the large roller, the second large roller, the middle roller, the second small roller and the small roller are all concave surfaces contacting the outer peripheral wall of the pipe fitting.

3. A large-diameter thick-walled bending tube forming die as claimed in claim 1, characterized in that: A second avoidance groove is provided at the connection position of the discharge groove and the curved groove, and a straight wall section auxiliary roller group is provided in the second avoidance groove. The straight wall section auxiliary roller group includes a plurality of auxiliary rollers, and each auxiliary roller is rotatably arranged in the second avoidance groove.

4. A large-diameter thick-walled bending tube forming die as claimed in claim 3, characterized in that: The number of the auxiliary rollers is 5, the size of each of the auxiliary rollers is the same, and the outer peripheral wall of each auxiliary roller is a concave surface in contact with the outer peripheral wall of the pipe.

5. A large-diameter thick-walled bending tube forming die as claimed in claim 2 or 4, characterized in that: The position of each roller facing the pipe is the inner side, and the position away from the pipe is the outer side; the ends of two adjacent rollers contact each other near the inner side, so that the concave surfaces of the rollers form a complete circumferential surface.

6. A large-diameter thick-walled bending tube forming equipment, characterized in that: It comprises a frame and a molding die as claimed in any one of claims 1 to 5, wherein the lower die is fixed on the ground; the frame is provided with a mold clamping hydraulic cylinder, and the piston rod of the mold clamping hydraulic cylinder is connected to the upper die; The frame is also provided with a push hydraulic cylinder, the piston rod of which is connected with a punch, and the punch is used to push the pipe fittings in the discharge trough; A turning platform is provided on one side of the frame, and one end of the inner mold core is connected to the turning platform.

7. A molding method using the molding die according to any one of claims 1 to 5, characterized in that: The following steps are involved: The pipe fitting is placed in the discharge groove of the lower mold, and the upper mold and the lower mold are closed to limit the pipe fitting in the circumferential direction; The punch slides in the discharge trough to push the pipe in the discharge trough; the pipe is plugged into the inner die core under the pushing action of the punch, and the outer peripheral wall of the pipe rotates with the auxiliary roller group of the bending section; When the punch is pushed into place, the pipe is formed; The upper mold is reset upward, and the inner mold core drives the pipe fitting to flip out of the discharge chute, and the pipe fitting after bending and forming is separated from the inner mold core.

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