A trailing arm of a torsion beam, a torsion beam assembly and a method for manufacturing a trailing arm

Abstract

The application discloses a torsion beam longitudinal arm, a torsion beam assembly and a longitudinal arm manufacturing method. The longitudinal arm comprises a first part and a second part which are distributed in a circumferential direction, a transition part is arranged between the first part and the second part, and the first part, the second part and the transition part enclose a tubular structure. The wall thickness of the first part is greater than that of the second part. The longitudinal arm increases the wall thickness of the welding position of the longitudinal arm and the cross beam, and compared with increasing the wall thickness of the whole longitudinal arm, the strength of the longitudinal arm can be improved while the light weight is realized, the fatigue failure risk of the welding position of the longitudinal arm and the cross beam is reduced, and the fatigue life of the welding position of the longitudinal arm and the cross beam can be increased by about 25%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile torsion beam trailing arm, in particular to a torsion beam trailing arm, a torsion beam assembly and a method for manufacturing the trailing arm. BACKGROUND

[0002] The automobile suspension system includes front suspension and rear suspension, which connects the wheels and the body, and ensures the good operation of the automobile by absorbing various excitations of the ground, especially the automobile rear suspension is most important for the operability and comfort of the vehicle. With the continuous development of electric vehicles, the weight brought by the size of the battery is increasingly demanding on the load bearing of the rear axle of the vehicle. Due to the cost pressure, the torsion beam type non-independent suspension is widely used in the rear suspension system of the automobile by many automobile manufacturers. Compared with other suspension structures, it has the advantages of simple structure, low production cost, excellent lightweight and easy maintenance.

[0003] The torsion beam rear axle belongs to a semi-independent suspension system, which has the structural characteristics of a non-independent suspension from the structural analysis, and has the buffering and damping performance of an independent suspension from the performance analysis. The torsion beam rear axle is usually composed of two side trailing arms, a cross beam, a spring, a shock absorber bracket, a rubber bushing, a hub disc and a support seat. The torsion beam rear suspension can balance the body vibration caused during the driving of the automobile, and ensure the smooth operation of the automobile. However, as the trailing arm component connecting the wheels and the body, it bears various loads from the wheel center during the operation of the suspension, and is prone to local stress concentration areas. Therefore, the trailing arm of the torsion beam is a component prone to fatigue damage, so the trailing arm itself must have good stiffness and strength. In addition, the trailing arm is connected with the cross beam by welding, and there is a high risk of fatigue failure at the welding position.

[0004] With the increasing demand for load bearing of the rear axle of the vehicle, the structure of the trailing arm of the torsion beam is becoming more and more complex. On the one hand, the trailing arm structure needs to ensure good strength and stiffness, and on the other hand, it also needs to consider the process feasibility and cost advantage. The structural design and manufacturing process of the torsion beam trailing arm component have become the key work of the vehicle rear axle layout. The common process forms of the trailing arm are sheet metal stamping and welding and hydraulic forming of round pipe. Sheet metal stamping and welding can increase the cross section of the trailing arm in the place where the stress is large, and the stress distribution is reasonable, but it introduces two welds through the trailing arm, which brings risks to the fatigue durability of the structure. Hydraulic forming of round pipe has good stiffness and strength, but the cost is high, and the process has certain requirements for the bend angle, generally requiring the diameter of the inside bend to be greater than 2 times the outer diameter of the pipe.

[0005] During the development and design of the torsion beam rear axle, the trailing arm as a key component, its structural design and process selection are related to the load bearing strength, stiffness, fatigue life and cost advantage of the entire rear axle. SUMMARY

[0006] To solve at least one of the above technical problems, the application provides a trailing arm of a torsion beam, a torsion beam assembly and a trailing arm manufacturing method.

[0007] The application solves the technical problems by using the following technical solutions.

[0008] In a first aspect, the application provides a trailing arm of a torsion beam, which comprises a first part and a second part distributed circumferentially, and has a transition part between the first part and the second part, and the first part, the second part and the transition part enclose a tubular structure; the wall thickness of the first part is greater than that of the second part.

[0009] Further, the first part has a weld extending in the longitudinal direction in the middle, which is arranged at a position with a greater wall thickness, thereby improving the strength of the trailing arm.

[0010] Further, the transition part is arranged in the shape of an isosceles trapezoid, and the acute angle of the isosceles trapezoid is arranged to be 40-60°, so that the first part and the second part can be smoothly transitioned, stress concentration is reduced, and the fatigue durability of the trailing arm is improved.

[0011] Further, the acute angle of the isosceles trapezoid is arranged to be 45°.

[0012] In a second aspect, the application provides a torsion beam assembly, which comprises two or more trailing arms as described above, and further comprises a cross beam, and the two ends of the cross beam are respectively connected to the first parts of the two trailing arms, so that the welding position of the trailing arm and the cross beam is located at a position with a greater wall thickness, thereby reducing the fatigue failure risk of the welding position.

[0013] In a third aspect, the application provides a trailing arm manufacturing method of a torsion beam, which is used to manufacture the trailing arm as described above, and the method comprises the following steps.

[0014] In step 100, a plate material is rolled, and the plate material is rolled into an A region, a transition region, a B region, a transition region and a C region in sequence along a first direction, the thicknesses of the A region, the transition region and the B region correspond to the wall thicknesses of the first part, the transition part and the second part of the trailing arm respectively, and the thicknesses of the A region and the C region are the same;

[0015] In step 200, a first pipe is rolled from the rolled plate material.

[0016] Step 300, stamping, stamping the first pipe to obtain the second pipe, so that the two ends of the second pipe are consistent with the two ends of the longitudinal arm product;

[0017] Step 400, welding, welding the overlapping edges of the pipe.

[0018] Further, the method for rolling the plate comprises:

[0019] Step 101, obtaining a plate blank, the plate blank being a rectangular plate with a length a, a width b, and a thickness c;

[0020] Step 102, first rolling the plate blank to roll the thickness c of the plate blank to c0 to obtain a first plate;

[0021] Step 103, dynamically adjusting the roll gap to match the preset thickness of the to-be-rolled area, and segmentally rolling each area in the first direction to obtain a second plate;

[0022] Step 104, trimming the second plate to obtain a third plate, the outer contour of the third plate matching the contour of the planar development structure of the longitudinal arm along a longitudinal line L of the first part.

[0023] Further, the method for rolling the pipe comprises:

[0024] Step 201, pre-bending the end Q1 and the end Q2 of the third plate with the end P2 of the third plate as the starting end to form a pipe butt joint edge;

[0025] Step 202, in the second direction, dividing the third plate into a plurality of plate segments according to the curvature of each curve segment of the longitudinal line L, approximating each curve segment of the longitudinal line L with a circular arc, determining the radius of each circular arc segment, and rolling each plate segment into a straight pipe with the end P2 of the third plate as the starting end according to the radius of each circular arc segment; and in the rolling process of each straight pipe segment, the roller spacing near the end P1 is smaller than the roller spacing near the end P2;

[0026] Step 203, determining the twist angle of each circular arc segment, and bending each straight pipe segment according to the twist angle to obtain a first pipe.

[0027] Further, the welding method comprises the following steps:

[0028] Step 401, multiple spot welding of the overlapping edges;

[0029] Step 402, full welding of the overlapping edges.

[0030] Further, the manufacturing method further comprises trimming, deburring, and detecting the welded pipe.

[0031] Compared with the prior art, the present application has the beneficial effects that:

[0032] (1) The longitudinal arm increases the wall thickness of the welding position of the longitudinal arm and the cross beam, and compared with increasing the wall thickness of the whole longitudinal arm, the strength of the longitudinal arm can be improved while realizing lightweight, the fatigue failure risk of the welding position of the longitudinal arm and the cross beam can be reduced, and the fatigue life of the welding position of the longitudinal arm and the cross beam can be improved by about 25%.

[0033] (2) The longitudinal arm manufacturing method can manufacture a longitudinal arm with variable cross section in the longitudinal direction and variable thickness in the circumferential direction, has short production rhythm and low production cost; and the longitudinal arm has only one welding seam, the strength of the longitudinal arm can be improved, the longitudinal arm has good rigidity and good fatigue durability, and the fatigue life of the longitudinal arm can be improved by about 15%. BRIEF DESCRIPTION OF DRAWINGS

[0034] For better understanding of the above and other objects, features, advantages and functions of the present application, reference can be made to the embodiments shown in the drawings. The same reference signs in the drawings refer to the same parts. Those skilled in the art should understand that the drawings are intended to illustrate the preferred embodiments of the present application schematically, and have no limiting effect on the scope of the present application, and the various parts in the drawings are not drawn to scale.

[0035] Figure 1 is a longitudinal arm structure schematic diagram of the torsion beam of the present application.

[0036] Figure 2 is an A-A cross section structure schematic diagram.

[0037] Figure 3 is a B-B cross section structure schematic diagram.

[0038] Figure 4 is a torsion beam assembly structure schematic diagram of the present application.

[0039] Figure 5 is a process flow chart of the longitudinal arm manufacturing method of the present application.

[0040] Figure 6 is a rolling process flow chart of the present application.

[0041] Figure 7 is a pipe winding process flow chart of the present application.

[0042] In the drawings: 1, longitudinal arm; 11, first part; 12, second part; 13, transition part; 14, first opening; 15, second opening; 2, cross beam; 3, flange plate; 4, sleeve. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the present application clearer, the following will describe the exemplary embodiments of the present disclosure in conjunction with the drawings, which include various details of the embodiments of the present disclosure to help understanding, and should be considered as merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Also, for the sake of clarity and conciseness, the description below omits the description of well-known functions and structures.

[0044] In the description of the present application, it should be noted that the term "comprising" and its variants means open inclusion, i.e. "including, but not limited to". The terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly and specifically limited.

[0045] In the first aspect, the longitudinal arm 1 is connected with the cross beam 2 by welding, and there is a great risk of fatigue failure at the welding position of the longitudinal arm 1. In order to improve the fatigue characteristics of the part, the present application provides a longitudinal arm of a torsion beam, as shown in the figure, the longitudinal arm 1 includes a first part 11 and a second part 12 distributed circumferentially, the first part 11 and the second part 12 have a transition part 13 therebetween, the first part 11, the second part 12 and the transition part 13 form a tubular structure, and the wall thickness of the first part 11 is greater than that of the second part 12. Figures 1-3 The longitudinal arm 1 has a large change in each cross section in the longitudinal direction, and each part of the longitudinal arm 1 has a different thickness in the circumferential direction, and the wall thickness of each part in the longitudinal direction is the same. The first part 11 and the second part 12 have a thickness difference, and the transition part 13 is arranged between the first part 11 and the second part 12 to allow smooth transition between the first part 11 and the second part 12.

[0046] Preferably, the wall thickness d1 of the first part 11 can be set to 1.2-2 times the wall thickness d2 of the second part 12. For example, the wall thickness d1 of the first part 11 can be set to 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times or 2 times the wall thickness d2 of the second part 12, etc. Exemplarily, the wall thickness d2 of the second part 12 of a certain vehicle model longitudinal arm 1 is 3mm, and the wall thickness d1 of the first part 11 is 4mm, and the wall thickness d2 of the second part 12 of another vehicle model longitudinal arm 1 is 3.5mm, and the wall thickness d1 of the first part 11 is 5mm.

[0047] The longitudinal arm 1 increases the wall thickness of the welding position of the longitudinal arm 1 and the cross beam 2, and compared with increasing the wall thickness of the entire longitudinal arm 1, the strength of the longitudinal arm 1 can be improved while achieving light weight. The welding of the cross beam 2 and the second part 12 can reduce the fatigue failure risk of the welding position of the longitudinal arm 1 and the cross beam 2 and improve the fatigue life of the welding position of the longitudinal arm 1 and the cross beam 2 by about 25%.

[0048] In some embodiments, the middle part of the first part 11 has a welding seam extending in the longitudinal direction. When the longitudinal arm 1 is manufactured by welding process, the welding seam is arranged at the position with larger wall thickness, so that the strength of the longitudinal arm 1 can be improved, the longitudinal arm 1 has good rigidity and fatigue durability, and the fatigue life of the longitudinal arm 1 can be improved by about 15%.

[0049] In some embodiments, the transition part 13 is arranged as an isosceles trapezoid, the acute angle of the isosceles trapezoid is arranged as 40-60°, for example, the acute angle of the isosceles trapezoid can be arranged as 40°, 45°, 50°, 55° or 60°, etc., so that the first part 11 and the second part 12 can be smoothly transitioned, the stress concentration is reduced, and the fatigue durability of the longitudinal arm 1 is improved. Preferably, when the acute angle of the isosceles trapezoid is arranged as 45°, the smooth transition effect is better.

[0050] In a second aspect, the present application also provides a torsion beam assembly, referring to Figures 1-4 the torsion beam assembly includes two longitudinal arms 1 and also includes a cross beam 2, the two ends of the cross beam 2 are connected to the first parts 11 of the two longitudinal arms 1, so that the welding position of the longitudinal arm 1 and the cross beam 2 is located at the position with larger wall thickness, and the fatigue failure risk of the welding position is reduced.

[0051] Generally, the cross beam 2 is connected to the first part 11 of the longitudinal arm 1 by welding, so that the welding position of the longitudinal arm 1 and the cross beam 2 is located at the position with larger wall thickness, and the fatigue failure risk of the welding position is reduced. Preferably, the circumference of the first part 11 at the welding seam of the cross beam 2 and the longitudinal arm 1 is at least 70% of the length of the welding seam in the circumferential direction of the longitudinal arm 1, for example, the circumferential length of the first part 11 at the welding seam can be 70%, 80%, 90%, 100%, 110%, 120% or the like of the length of the welding seam, so that the welding position is located at the first part 11 with larger wall thickness as much as possible, and the fatigue failure risk caused by welding is reduced.

[0052] In a third aspect, the present application provides a manufacturing method of a longitudinal arm of a torsion beam, which is used to manufacture the longitudinal arm 1 of any one of the above embodiments, as shown in Figure 5 the manufacturing method includes the following steps:

[0053] Step 100, rolling the plate, sequentially rolling the plate into A region, transition region, B region, transition region and C region along the first direction, the thicknesses of A region, transition region and B region correspond to the wall thicknesses of the first part 11, transition part 13 and second part 12 of the longitudinal arm 1 respectively, and the thicknesses of A region and C region are the same;

[0054] Step 200, pipe rolling, rolling the rolled plate into a first pipe;

[0055] Step 300, stamping, stamping the first pipe to obtain a second pipe, so that the two ends of the second pipe are consistent with the two ends of the finished longitudinal arm 1;

[0056] Step 400, welding, welding the overlapping edges of the pipe.

[0057] In step 100, different thicknesses of different regions can be realized by dynamically adjusting the roll gap and using longitudinal step rolling process, and the widths of A region and C region are approximately the same.

[0058] In step 300, the first pipe is used to stamp the first opening 14 adapted to the flange plate 3 at one end of the flange plate 3 and the second opening 15 adapted to the sleeve 4 at one end of the sleeve 4 to obtain the second pipe. A multi-process die can be used when stamping the first pipe. The first stamping process realizes the stamping of the first opening 14 at the end W1, and the second stamping process realizes the stamping of the second opening 15 at the end W2. After the first stamping process and the second stamping process, the second pipe can be obtained. The stamping dies of each stamping process can be designed according to the geometric shape of the finished longitudinal arm 1.

[0059] After obtaining the second pipe, final finishing before welding is still needed to ensure the smooth development of subsequent welding. A single-process finishing die with high precision and simple structure can be used to finish the ends W1 and W2, ensuring the flatness of the subsequent welding of the flange plate 3 and the precision of the welding of the sleeve 4. At the same time, the overlapping edges for welding are finished to reserve appropriate welding gaps and improve the welding quality and pipe strength. The finishing die can be designed according to the geometric shape of the finished longitudinal arm 1, and the die has high precision to realize fine finishing before welding. After finishing the second pipe, the overlapping edges of the pipe can be welded.

[0060] In some embodiments, referring to Figure 6 the method for rolling the plate includes:

[0061] Step 101, obtaining a plate blank, the plate blank is a rectangular plate with a length of a, a width of b and a thickness of c;

[0062] Step 102, first rolling the plate blank, rolling the thickness c of the plate blank to c0 to obtain a first plate;

[0063] Step 103, dynamically adjusting the roll gap to adapt the roll gap to the preset thickness of the to-be-rolled region, segmentally rolling each region in the first direction to obtain a second plate;

[0064] Step 104, trimming the second plate to obtain a third plate, the outer contour of the third plate being adapted to the contour of the planar development structure of the longitudinal arm 1 along a longitudinal line L of the first part 11.

[0065] Simulation software suitable for the stamping process, such as AutoForm, Dynaform, PAM-STAMP, etc., can be used for simulation. After importing the 3D model of the product into the software, the plate blank size can be obtained. In step 101, the plate blank can be obtained by traditional mechanical shearing and blanking process. The upper and lower blades can be used to shear the straight edges, and a rectangular plate with a length of a, a width of b, and a thickness of c can be obtained. This process has low cost and simple operation, and is suitable for straight-line blanking of rectangular plates. In step 102, the material thickness can be roughly rolled to be uniform after the first rolling of the plate blank, and a first plate with a relatively clean surface, moderate thickness, and regular shape can be obtained.

[0066] In step 103, the first plate is rolled to meet the specific thickness requirement according to the thickness requirement of different regions to obtain a second plate. Specifically, different thickness requirements of different regions can be achieved by dynamically adjusting the roll gap and using longitudinal step rolling process. First, adjust the roll gap to adapt to the preset thickness c1 of region A, and roll region A for the second time to change the thickness of region A from c0 to c1; the intersection position of region A and region B is rolled by smooth transition to obtain transition region G, the cross section of transition region G is isosceles trapezoidal, and the transition between region A and region B is smooth; then adjust the roll gap to adapt to the preset thickness c2 of region B, and roll region B for the second time to change the thickness of region B from c0 to c2; then roll the intersection position of region B and region C by smooth transition to obtain transition region G, the cross section of transition region G is isosceles trapezoidal, and the transition between region B and region C is smooth; then, adjust the roll gap to adapt to the preset thickness c1 of region C, and roll region C for the second time to change the thickness of region C from c0 to c1, thereby segmentally rolling different thicknesses in the first direction.

[0067] In step 104, the outer profile of the end portion P1 of the third plate material extending in the first direction is adapted to the profile of the end portion W1 of the longitudinal arm 1 rough blank unfolded at the intersection of the longitudinal line L and the profile of the end portion W1; the outer profile of the end portion P2 of the third plate material extending in the first direction is adapted to the profile of the end portion W2 of the longitudinal arm 1 rough blank unfolded at the intersection of the longitudinal line L and the profile of the end portion W2; and the outer profiles of the end portion Q1 and the end portion Q2 of the third plate material in the second direction perpendicular to the first direction are adapted to the longitudinal line L of the longitudinal arm 1.

[0068] According to the structure of the finished longitudinal arm 1, the structure of the longitudinal arm 1 rough blank can be obtained by simulation software of the stamping process, and the planar unfolded structure of the longitudinal arm 1 rough blank unfolded along the longitudinal line L can be obtained. Then, the second plate material with different thicknesses is finely trimmed according to the planar unfolded structure, and a single-process die cutting trimming with a simple shape can be used. The structure of the die cutting die can be designed according to the outer profile around the planar unfolded structure, and then the second plate material is pressed by using a press and a die cutting die, so that the plate material is separated according to the shape of the die cutting die, thereby obtaining a pre-formed third plate material, which meets the size profile requirements of the subsequent process.

[0069] It can be understood that the finished longitudinal arm 1 is a longitudinal arm 1 structure installed on a vehicle, and the longitudinal arm 1 rough blank is a longitudinal arm 1 structure without the first opening 14 and the second opening 15 punched. The longitudinal line is a spatial curve along the axis direction of the pipe fitting, connecting the cross-sectional profiles of the two ends of the pipe fitting, and bending with the change of the cross section. The first direction is the thickness change direction of the plate material.

[0070] In some embodiments, as shown in FIG. 1, the method of rolling a pipe includes: Figure 7

[0071] Step 201, pre-bending the end portion Q1 and the end portion Q2 of the third plate material with the end portion P2 of the third plate material as the starting end to form a pipe butt joint edge;

[0072] Step 202, in the second direction, the third plate material is divided into a plurality of plate segments according to the curvature of each curve segment of the longitudinal line L, and each curve segment of the longitudinal line L is approximated by a circular arc to determine the radius of each circular arc segment. According to the radius of each circular arc segment, the third plate material is rolled into a straight pipe with the end portion P2 as the starting end; and in the rolling process of each straight pipe segment, the roller spacing near the end portion P1 is smaller than the roller spacing near the end portion P2.

[0073] Step 203, determining the torsion angle of each circular arc segment, and bending each straight pipe segment according to the torsion angle to obtain a first pipe fitting.

[0074] ​The simulation software COPRA® RF, AutoForm, Dynaform, PAM-STAMP, etc. suitable for the tube rolling process can be used to calculate the size of the planar development structure according to the geometric parameters of the variable cross-section, which is roughly a sector or trapezoid with a difference in the side length of the large end and the small end, forming an oblique side. In step 201, the two oblique sides of the plate are pre-bent, and the plate rolling machine can be used for pre-bending. When using the plate rolling machine for pre-bending, it is preferred to gradually realize the curvature gradually pre-bending from the end P2 (small end) to the end P1 (large end) to prevent defects such as small end wrinkles, large end springback exceeding the standard, overall axis deviation, etc. The small end has a small curvature radius, and the roller spacing can be adjusted to increase the pressure. The large end has a large curvature radius, and the roller spacing can be adjusted to reduce the pressure. After pre-bending, cut according to the design allowance to form the butt joint edge of the tube.

[0075] In step 202, it is preferred to gradually extend from the end P2 (small end) to the end P1 (large end) of the third plate as a reference, and gradually roll from the small end to the large end. The small end is used as the starting end for rolling, the circumference is short, the bending resistance is small, the stable arc can be quickly established, and the subsequent large end rolling relies on this reference, which can effectively avoid the problems of oblique side wrinkles, stress concentration and butt joint edge misalignment. During the rolling process of each section of straight pipe, as the bending degree of the plate end Q1 and the end Q2 increases, the pressing position of the pressure roller gradually changes from the thick area A region and the C region to the thin area B region. During rolling, the roller spacing near the end P1 is smaller than the roller spacing near the end P2, which can adjust the rolling pressure and control the uniformity of deformation in different thickness regions. The plate rolling machine can preferably use a three-roller plate rolling machine and a four-roller plate rolling machine. During rolling, it is convenient to adjust the spacing and inclination angle of the upper and lower rollers of the plate rolling machine, so that the plate is gradually rolled into a conical pipe along the rolling radius.

[0076] In step 203, a numerical control pipe bender or a special jig can be used to space-bend each section of straight pipe. During bending, the pipe section is rotated according to the torsion angle of each circular arc, and the bending of each section is completed in turn.

[0077] After the tube rolling is completed, final trimming and detection before welding can be performed. For example, after rolling is completed, the butt joint edge is brought together, a inside support tool (such as a rice-shaped support rib) is used to correct the circle of the tube, to ensure that the ellipticity meets the requirements, and a three-dimensional coordinate measuring instrument is used to detect the center line deviation. Flame correction or mechanical correction is used for local excessive deviation positions to ensure the smooth development of subsequent welding.

[0078] In some embodiments, the welding method comprises the following steps:

[0079] Step 401, multiple spot welding is performed on the lap joint edge to fix it;

[0080] Step 402, full welding is performed on the lap joint edge.

[0081] For the joint of the lap joint edge of the pipe, a traditional gas shielded welding process can be used. First, pre-welding is performed for continuous spot welding fixation to prevent subsequent welding deformation. Then, main welding is performed to perform full welding on the weld joint. The main welding can use an outside welding process to achieve the welding forming of the gap. The welding process can be filled with argon on the inside to achieve weld protection to prevent oxidation, and finally achieve the weld joint of the lap joint edges Q1 and Q2. After welding, the A area and the C area are connected into one body to form the first part 11 of the longitudinal arm 1 with a large wall thickness. Although stress concentration is easy to occur at the welding position, the longitudinal arm 1 has only one weld joint and is located at a position with a large wall thickness, which can improve the strength of the longitudinal arm 1, make the longitudinal arm 1 have good rigidity and fatigue durability, and can improve the fatigue life of the longitudinal arm 1 by about 15%.

[0082] After the pipe is welded and formed, the welded pipe needs to be deburred and burr treated. The deburring and straightening are mainly performed on the weld joint position. A hydraulic straightening machine can be used to eliminate welding deformation, make the straightness of the weld joint ≤1mm / m, and polish the weld joint excess height to be flush with the base material. Finally, ultrasonic nondestructive testing is performed to screen pores or cracks, and the qualified product is the longitudinal arm 1 product.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A trailing arm of a torsion beam, characterized in that, The longitudinal arm comprises a first portion and a second portion distributed along a circumference, and a transition portion between the first portion and the second portion, the first portion, the second portion and the transition portion enclosing a tubular structure; the first portion has a same wall thickness in a longitudinal direction, the second portion has a same wall thickness in the longitudinal direction; the wall thickness of the first portion is greater than the wall thickness of the second portion, and a middle part of the first portion in the longitudinal direction is used for welding an end part of the cross beam.

2. The trailing arm of a torsion beam according to claim 1, characterized in that The middle part of the first portion has a welding seam extending along the longitudinal direction.

3. The trailing arm of a torsion beam according to claim 1, characterized in that, The transition portion is arranged as an isosceles trapezoid, and an acute angle of the isosceles trapezoid is arranged as 40-60°.

4. The trailing arm of a torsion beam according to claim 3, characterized in that The acute angle of the isosceles trapezoid is arranged as 45°.

5. A torsion beam assembly, comprising: The method comprises the following steps:

6. A method of manufacturing a trailing arm of a torsion beam, for manufacturing a trailing arm according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: Step 100, rolling a plate, sequentially rolling the plate along a first direction to obtain an A region, a transition region, a B region, a transition region and a C region, the thicknesses of the A region, the transition region and the B region correspond to the wall thicknesses of the first portion, the transition portion and the second portion of the longitudinal arm respectively, and the thicknesses of the A region and the C region are the same; Step 200, rolling a pipe, rolling the plate after rolling to obtain a first pipe; Step 300, stamping, stamping the first pipe to obtain a second pipe, so that the two ends of the second pipe are consistent with the two ends of the finished longitudinal arm; Step 400, welding, welding the overlapping edges of the pipe.

7. The method of claim 6, wherein: The method for rolling a plate comprises: Step 101, obtaining a plate blank, the plate blank is a rectangular plate with a length a, a width b and a thickness c; Step 102, performing first rolling on the plate blank, rolling the thickness c of the plate blank to c0 to obtain a first plate; Step 103, dynamically adjusting a roll gap, so that the roll gap is matched with a preset thickness of a region to be rolled, and sequentially rolling each region in the first direction to obtain a second plate; Step 104, trimming the second plate to obtain a third plate, and an outer contour of the third plate is matched with a contour of a planar development structure of a longitudinal line L of the longitudinal arm.

8. The method of claim 7, wherein: The method for rolling a pipe comprises: Step 201, pre-bending an end part Q1 and an end part Q2 of the third plate with an end part P2 of the third plate as a starting end to form a pipe butt joint edge; Step 202, in a second direction, dividing the third plate into a plurality of plate segments according to the curvatures of each curve segment of the longitudinal line L, approximating each curve segment of the longitudinal line L with a circular arc, determining the radii of each circular arc segment, and rolling each plate segment into a straight pipe with the end part P2 of the third plate as the starting end according to the radii of each circular arc segment; and in the rolling process of each straight pipe, the roll spacing close to the end part P1 is less than the roll spacing close to the end part P2; Step 203, determining a torsion angle of each circular arc segment, and bending each straight pipe according to the torsion angle to obtain a first pipe.

9. The method of claim 6, wherein: The welding method comprises the following steps: Step 401, multiple spot welding is performed on the overlapping edges; Step 402, full welding is performed on the overlapping edges.

10. The method of claim 9, wherein: The manufacturing method further comprises trimming, deburring and detecting the pipe after welding.

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