CN-121997483-A - Method for forming continuous bending closed pipe

CN121997483ACN 121997483 ACN121997483 ACN 121997483ACN-121997483-A

Abstract

The invention provides a continuous bending closed pipe forming method which comprises the steps of obtaining a target contour of a bent pipe, determining a theoretical core wire based on the target contour, determining a pipe blank contour and a preformed core wire based on the theoretical core wire, determining the preformed core wire based on the preformed core wire, forming the pipe blank to the preformed core wire in a modeling tool to obtain a first compensation amount, forming the preformed core wire to the target contour in the modeling tool to obtain a second compensation amount, determining a target molded surface of a mold according to the second compensation amount, determining parameters of the mold according to the target core wire and the target molded surface, designing corresponding molds respectively, and sequentially placing the pipe blank into the molds to form the target contour. According to the invention, by adopting the pipe blank to the preform and the preform to the target contour, each part is independently simulated, and the compensation quantity is calculated in advance in the earlier stage of the design of the die, so that the specific parameters of the die are determined, the qualification rate of the formed size of the product is improved, and the subsequent rectifying risk caused by out-of-tolerance rebound is reduced.

Inventors

SU HAIBO
TONG JUN
XIONG YIMOU
YANG JINGAO
LUO QIANGFENG
PENG LI

Assignees

保隆(安徽)汽车配件有限公司

Dates

Publication Date: 20260508
Application Date: 20251226

Claims (10)

1. A method for forming a continuous bending closed tube is characterized by comprising the following steps of Acquiring a target contour of the bent pipe to be molded, and determining a theoretical core wire based on the target contour; determining a tube blank and a preformed blank according to the theoretical core wire, and determining the die opening direction, the die opening position and the preformed core wire of the tube blank in a die according to the preformed blank; Sequentially performing preforming to a preform and performing secondary forming to a target contour on the tube blank in a modeling tool based on the die opening direction and the die opening position, and determining compensation amounts in the preforming and secondary forming processes according to the preformed core wire, the preforming and the secondary forming; determining parameters of the mold according to the compensation amount and respectively designing a preformed mold and a secondary molding mold; And sequentially placing the tube blank into a pre-forming die and a secondary forming die to form the tube blank into a target profile.
2. The method of forming a continuously curved closed tube according to claim 1, wherein said obtaining a target profile of the bent tube and determining a theoretical core line based on said target profile comprises: Acquiring a projection curve of the bent pipe along the extending direction of the bent pipe, and selecting a plurality of projection points on the projection curve at equal intervals; Establishing a plane for each projection point, wherein the planes are normal planes of projection curves, and obtaining a plurality of target contour surfaces according to intersecting lines of the normal planes and the outer contour surfaces of the bent pipes and two end surfaces of the bent pipes; And extracting the center points of the target profile surfaces, and connecting the center points in sequence to obtain a theoretical core wire.
3. The method for forming a continuously curved closed tube according to claim 2, wherein said determining the tube blank from said theoretical core wire comprises: determining the perimeter of each target profile surface according to the target profile surface, and determining the outer diameter of the tube blank according to the perimeter of the largest target profile surface; respectively adding a transition section and a sealing section at two ends of the target profile, and determining the theoretical length of the tube blank according to the theoretical core wire, the transition section and the sealing section; And determining the profile of the tube blank according to the outer diameter of the tube blank, the theoretical length of the tube blank and the wall thickness of the bent tube.
4. The method of forming a continuously curved closed tube as claimed in claim 3, wherein said determining a preformed core wire based on said preform comprises: Determining machining allowance according to the profile of the tube blank and the target profile, and determining the profile of the preform according to the profile of the tube blank and the machining allowance; the preform core wire is determined according to the profile of the preform.
5. The method for forming a continuously curved closed tube according to claim 3, wherein said determining the die opening direction and the die opening position of the tube blank in the die from the preform comprises: Determining the mold opening direction according to the side wall of the preform, wherein the side wall of the preform is parallel to the mold opening direction; The die comprises an upper die and a lower die, theoretical process profiles of the upper die and the lower die are determined according to the preformed blank, and after the upper die and the lower die are clamped, the maximum profile of the tube blank is located in the lower die.
6. The method of forming a continuously curved closed tube according to claim 5, wherein said determining the die opening direction and the die opening position of the tube blank in the die from the preform further comprises: Introducing each theoretical process profile, the tube blank and the preform into analysis software, and carrying out grid division on the theoretical process profiles; Determining, by analysis software, first parameters of tube blank forming to the preform, the first parameters including a low pressure and an expansion pressure; Determining a second parameter of the preform molded to the target profile by analysis software, wherein the second parameter comprises molding pressure and the feeding lengths of the two ports; And determining the actual length of the tube blank through the compensation length and the theoretical length of the tube blank.
7. The method of forming a continuously curved closed tube according to claim 1, wherein said determining the amount of compensation in the preforming and post-forming processes comprises: Determining a first compensation amount according to the preformed blank and the actual profile after the preformed; determining a target core wire according to the preformed core wire and a first compensation amount; determining a second compensation amount according to the target contour and the actual contour after secondary molding; and determining the target molded surface of the secondary molding die according to the second compensation amount.
8. The method of forming a continuously curved closed tube as claimed in claim 7, wherein the determining the target core wire from the preformed core wire and the first compensation amount comprises: guiding the tube blank into a modeling tool, forming the tube blank into a preformed blank to obtain a first rebound contour, and determining a rebound core wire according to the first rebound contour; comparing the rebound core wire with the preformed core wire, and determining the gap value between the rebound core wire and the preformed core wire at each position; And mirroring the rebound core wire according to the gap values at all positions by taking the preformed core wire as a reference, and determining the target core wire.
9. The method of forming a continuously curved closed tube according to claim 7, wherein said determining the target profile of the secondary forming die based on the second compensation amount comprises: introducing the preform into a modeling tool, and forming the preform to a target profile to obtain a second rebound profile; Comparing the second rebound profile with the preform, determining a profile difference between the preform and the second rebound profile; a second compensation amount is determined based on the profile difference.
10. The method of forming a continuously curved closed tube as claimed in claim 9, wherein determining the target profile of the mold based on the second compensation amount comprises: And mirroring the second rebound contour according to the profile difference everywhere by taking the theoretical process profile as a reference, and determining the target profile.

Description

Method for forming continuous bending closed pipe Technical Field The invention relates to the technical field of bending closed tube forming, in particular to a continuous bending closed tube forming method. Background Along with the rapid development of new energy automobiles, the requirements for chassis weight reduction and functionalization are increasingly increased, a hybrid vehicle type is used as an important branch part of new energy, more space is reserved for arranging a complete hybrid system on the basis of reserving the function of a transmission engine, a closed pipe fitting is used as one of important parts of the chassis, and on the basis of having good strength performance, the hybrid vehicle type is often designed into a continuous curved complex shape, and the cross section shape of the hybrid vehicle type is also a special-shaped structure. In the prior art, the bending process of the closed pipe comprises pipe bending and bending, but when the pipe bending process is adopted, in order to ensure that the pipe is not cracked in the pipe bending process, particularly when the pipe with small bending radius is processed, the number of layers of a pipe bending die is large, and the product is easy to wrinkle, slip and break because the cavity of a molding clamping die is difficult to ensure to completely wrap the product in the processing process. When the mandrel supporting bending process is adopted, the mandrel, the core balls and the core balls are connected through chain joints, the mandrel and the core ball assemblies are needed to be plugged into the tube blank before bending, the upper die lower protruding points and the straight tubes are extruded to cause two ends to tilt upwards in the bending process, the two ends of the upper die lower protruding points and the straight tubes are continuously lifted along with the continuous pressing, and therefore the two ends of the upper die lower protruding points and the straight tubes are continuously flattened. Therefore, the bent pipe is processed by adopting the two traditional processing techniques, so that the quality of the product is low. Disclosure of Invention The invention provides a continuous bending closed pipe forming method, which aims to solve the technical problem of low product quality manufactured by a pipe bending processing technology in the prior art. The invention provides a continuous bending closed pipe forming method, which comprises the following steps: Acquiring a target contour of the bent pipe to be molded, and determining a theoretical core wire based on the target contour; determining a tube blank and a preformed blank according to the theoretical core wire, and determining the die opening direction, the die opening position and the preformed core wire of the tube blank in a die according to the preformed blank; Sequentially performing preforming to a preform and performing secondary forming to a target contour on the tube blank in a modeling tool based on the die opening direction and the die opening position, and determining compensation amounts in the preforming and secondary forming processes according to the preformed core wire, the preforming and the secondary forming; determining parameters of the mold according to the compensation amount and respectively designing a preformed mold and a secondary molding mold; And sequentially placing the tube blank into a pre-forming die and a secondary forming die to form the tube blank into a target profile. In an embodiment of the present invention, the obtaining the target profile of the bent pipe, and determining the theoretical core line based on the target profile includes: Acquiring a projection curve of the bent pipe along the extending direction of the bent pipe, and selecting a plurality of projection points on the projection curve at equal intervals; Establishing a plane for each projection point, wherein the planes are normal planes of projection curves, and obtaining a plurality of target contour surfaces according to intersecting lines of the normal planes and the outer contour surfaces of the bent pipes and two end surfaces of the bent pipes; And extracting the center points of the target profile surfaces, and connecting the center points in sequence to obtain a theoretical core wire. In an embodiment of the present invention, the determining the tube blank according to the theoretical core wire includes: determining the perimeter of each target profile surface according to the target profile surface, and determining the outer diameter of the tube blank according to the perimeter of the largest target profile surface; respectively adding a transition section and a sealing section at two ends of the target profile, and determining the theoretical length of the tube blank according to the theoretical core wire, the transition section and the sealing section; And determining the profile of the tube blank according to the outer diameter of the tube bla