Welding process for automotive aluminum alloy front subframes

Abstract

This invention provides a welding process for automotive aluminum alloy front subframes, comprising the following steps: S1, welding the rear support, longitudinal beam, and front tower to form a longitudinal beam welded sub-assembly; during the welding process, the fixture rotates 90° so that the weld between the rear support and the longitudinal beam is in a horizontal position; the welding torch is offset from the rear support by 1.0-2.0 mm, with a forward tilt angle of 5-15°, a side tilt angle of 60-70°, a welding speed of 60-75 cm / min, and a wire feed speed of 8-10 m / min. This invention, through innovations in workpiece posture, welding torch tilt angle, welding process parameters, and weld arrangement, solves difficulties such as welding dissimilar aluminum alloys, welding aluminum alloys with varying thicknesses, root fusion incompleteness, and porosity, significantly improving weld quality, enhancing weld strength, reducing joint stress, increasing bench fatigue life by 3.4 times, and improving production efficiency. It can be widely applied to the welding process of aluminum alloy chassis for new energy vehicles.

Description

Technical Field

[0001] This invention relates to the field of automotive parts welding, and in particular to a welding process for automotive aluminum alloy front subframes. Background Technology

[0002] Currently, developing energy-saving and new energy vehicles and breaking through a series of key technologies for automotive lightweighting, represented by aluminum alloys, has become an inevitable choice and a major measure for my country to cope with energy shortages and environmental challenges.

[0003] Traditional steel front subframes cannot adapt to the development of new energy vehicles. Aluminum alloys are one of the preferred materials for automotive lightweighting. They are lightweight, only 1 / 3 the weight of steel, have high strength and good plasticity, and their mechanical properties can be changed through heat treatment. They also have good low-temperature performance.

[0004] Aluminum alloys offer excellent processing performance and corrosion resistance. They also exhibit good shock absorption, long fatigue life, and good impact resistance. Furthermore, they are non-magnetic, non-toxic, and do not produce sparks. In addition, aluminum alloys are recyclable and reusable, making them excellent "green materials." Research on lightweight aluminum structural components is of great significance for the lightweighting of vehicles.

[0005] In view of this, the inventors of this application have designed a welding process for aluminum alloy front subframes of automobiles in order to overcome the above-mentioned technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing steel front subframe that cannot adapt to the development of new energy vehicles, and to provide a welding process for aluminum alloy front subframes of automobiles.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] A welding process for an aluminum alloy front subframe for automobiles, characterized in that the welding process includes the following steps:

[0009] S1. Weld the rear support, longitudinal beam, and front tower to form the longitudinal beam welded sub-assembly; during the welding process, the fixture rotates 90° so that the weld between the rear support and the longitudinal beam is in a horizontal position;

[0010] The welding torch is offset from the rear support by 1.0-2.0 mm, the forward tilt angle is 5-15°, the side tilt angle is 60-70°, the welding speed is 60-75 cm / min, and the wire feeding speed is 8-10 m / min.

[0011] According to one embodiment of the present invention, the arc length of the weld is -15 to -5, and the inductance is 0 to 10.

[0012] According to one embodiment of the present invention, the welding process further includes:

[0013] S2. Weld the front beam, middle beam and rear beam to the longitudinal beam respectively to form a front subframe frame welding assembly;

[0014] Clean the parts to be welded before welding, heat the aluminum welding wire to 50°C to 65°C, and preheat the thick plate to 90°C to 120°C before welding.

[0015] The parts to be welded are rotated horizontally by 90°, with the rear support below and the rear beam above, for welding. According to one embodiment of the present invention, in step S2, the welding torch is offset from the rear support by 1.0-2.0 mm, the forward tilt angle is 0-8°, the side tilt angle is 60-80°, the welding speed is 60-80 cm / min, and the wire feed speed is 9-11 m / min.

[0016] According to one embodiment of the present invention, in step S2, the arc length of the welding is -8 to -18, and the inductance is 0 to 10.

[0017] According to one embodiment of the present invention, in step S2, the diameter of the welded pores is less than 1.0 mm.

[0018] According to one embodiment of the present invention, the welding process further includes:

[0019] S3. The first front subframe frame welding assembly is welded to the stabilizer bar bracket, the left steering gear bracket, the right steering gear bracket, the rear suspension beam, and the front suspension bracket to form the second front subframe frame welding assembly.

[0020] The welding process begins with the arc starting at both ends and ends in the middle. The arc introduction length is 5-15mm, the arc introduction angle is 90-110°, and the weld overlap at the middle arc end is 10-20mm.

[0021] According to an embodiment of the present invention, the weld formed by welding each part in step S3 includes a first weld, a second weld and a third weld, wherein the arc introduction length of the first weld is 10-20mm, the arc introduction angle is 80-100°, and the arc termination gap is 5-10mm.

[0022] The second weld has an arc starting in the middle and ending at both ends, with a 10-20mm interval between the two arc starting points and a 5-15mm gap at the two arc ending points;

[0023] The third weld has an arc starting at both ends and ending in the middle, with an arc introduction length of 10-20mm and an arc introduction angle of 130-150°. The weld overlaps by 10-20mm at the arc ending point.

[0024] According to one embodiment of the present invention, the welding process further includes:

[0025] S4. The second front subframe frame welding assembly is welded to the left control arm bracket, the right control arm bracket, the rear suspension bracket, the left and right reinforcing plates, and the front suspension beam to form the third front subframe frame welding assembly.

[0026] The arc starts at both ends and ends and ends at the middle 2 / 3 of the length. The arc initiation length is 30-50mm, the arc initiation angle is 135-155°, and the weld overlap at the arc end is 10-20mm.

[0027] According to one embodiment of the present invention, the welding process further includes:

[0028] S5. The front subframe frame welding assembly is welded to the right suspension bracket to form the front subframe welding assembly.

[0029] The positive and progressive effects of this invention are as follows:

[0030] This invention relates to the welding process of aluminum alloy front subframes for automobiles. Through innovations in workpiece posture, welding torch angle, welding process parameters, and weld arrangement, it solves challenges such as welding dissimilar aluminum alloys, welding aluminum alloys of varying thicknesses, root incomplete fusion, and porosity. This significantly improves weld quality, enhances weld strength, reduces joint stress, increases bench fatigue life by 3.4 times, and boosts production efficiency. It can be widely applied to the welding process of aluminum alloy chassis for new energy vehicles. Attached Figure Description

[0031] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein:

[0032] Figure 1 This is a structural diagram of an aluminum alloy front subframe for automobiles.

[0033] Figure 2 This is an improved schematic diagram of step one of the welding process for the aluminum alloy front subframe of an automobile according to the present invention.

[0034] Figure 3 This is an improved schematic diagram of step two of the welding process for the aluminum alloy front subframe of an automobile according to the present invention.

[0035] Figure 4 This is a schematic diagram of the steering gear bracket weld in step three of the welding process of the aluminum alloy front subframe of an automobile according to the present invention.

[0036] Figure 5 This is a schematic diagram of the suspended rear beam weld in step three of the welding process of the aluminum alloy front subframe of an automobile according to the present invention.

[0037] Figure 6This is a schematic diagram of the control arm bracket weld in step four of the welding process of the aluminum alloy front subframe of an automobile according to the present invention.

[0038] [Attached image labels]

[0039] Left rear support 10

[0040] Right rear support 11

[0041] Left longitudinal beam 20

[0042] Right longitudinal beam 21

[0043] Left front tower 30

[0044] Right front tower 31

[0045] Front beam 40

[0046] Zhongliang 50

[0047] Rear beam 60

[0048] Stabilizer bar bracket 70

[0049] Left steering gear bracket 80

[0050] Right steering gear bracket 90

[0051] 100mm Suspended Rear Beam

[0052] Front suspension bracket 110

[0053] Left control arm support 120

[0054] Right control arm bracket 130

[0055] Rear suspension bracket 140

[0056] Left reinforcing plate 150

[0057] Right reinforcing plate 160

[0058] 170mm front suspension beam

[0059] Right suspension bracket 180 Detailed Implementation

[0060] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0061] Embodiments of the invention will now be described in detail with reference to the accompanying drawings. Preferred embodiments of the invention will now be described in detail, examples of which are shown in the drawings. Wherever possible, the same reference numerals will be used in all the drawings to denote the same or similar parts.

[0062] Furthermore, although the terminology used in this invention is selected from commonly known and used terms, some terms mentioned in this specification may have been selected by the applicant in his or her judgment, and their detailed meanings are explained in the relevant sections of the description herein.

[0063] Furthermore, the invention should be understood not only through the actual terminology used, but also through the meaning implied by each term.

[0064] like Figure 1 As shown, the automotive aluminum alloy front subframe includes a rear support (including a left rear support 10 and a right rear support 11), longitudinal beams (including a left longitudinal beam 20 and a right longitudinal beam 21), front towers (including a left front tower 30 and a right front tower 31), a front beam 40, a center beam 50, a rear beam 60, a stabilizer bar bracket 70, a left steering gear bracket 80, a right steering gear bracket 90, a rear suspension beam 100, a front suspension bracket 110, a left control arm bracket 120, a right control arm bracket 130, a rear suspension bracket 140, a left reinforcing plate 150, a right reinforcing plate 160, a front suspension beam 170, and a right suspension bracket 180.

[0065] The left rear support 10, left longitudinal beam 20, and left front tower 30 are welded together to form a longitudinal beam welded sub-assembly. The right suspension bracket 11, right longitudinal beam 21, and right front tower 31 are welded together to form a longitudinal beam welded sub-assembly. The front beam 40, middle beam 50, and rear beam 60 are welded to the aforementioned longitudinal beam welded sub-assemblies to form the first front subframe frame welded assembly. The first front subframe frame welded assembly is welded to the stabilizer bar bracket 70, left steering gear bracket 80, right steering gear bracket 90, rear suspension beam 100, and front suspension bracket 110 to form the second front subframe frame welded assembly. The second front subframe frame welded assembly is welded to the left control arm bracket 120, right control arm bracket 130, rear suspension bracket 140, left reinforcing plate 150, right reinforcing plate 160, and front suspension beam 170 to form the third front subframe frame welded assembly. Finally, the front subframe frame welding assembly three is welded to the right suspension bracket 180 to form the front subframe welding assembly.

[0066] The aluminum alloy front subframe uses cast aluminum AlSi7Mg0.7 and aluminum profile 6082-T6 as raw materials, reducing weight by 40-50% compared to steel components. Welding uses ER5356 aluminum welding wire, 1.6mm in diameter, 99.999% Ar. This application describes a welding process for automotive aluminum alloy front subframes that utilizes multiple sub-assembly steps to release welding deformation. Critical dimensions are machined after welding, allowing dimensional tolerances to be controlled within ±0.5mm, thus improving product dimensional accuracy.

[0067] like Figure 2 As shown, this invention discloses a welding process for an aluminum alloy front subframe for automobiles, comprising the following steps:

[0068] Step S1: Weld the rear support, longitudinal beam, and front tower to form the longitudinal beam welded sub-assembly; during the welding process, the fixture rotates 90° so that the weld between the rear support and the longitudinal beam is in a horizontal position;

[0069] The welding torch is offset from the rear support by 1.0-2.0 mm, the forward tilt angle is 5-15°, the side tilt angle is 60-70°, the welding speed is 60-75 cm / min, and the wire feeding speed is 8-10 m / min.

[0070] Preferably, the arc length of the weld is -15 / -5, and the inductance is 0-10.

[0071] Since the thickness of the left and right rear suspension plates is usually 10mm, while the thickness of the left and right longitudinal beam plates is usually 2.5mm, the difference in plate thickness exceeds the recommended value of 1 times in the welding manual. The difference in plate thickness reaches 4 times, which is very easy to cause weld burn-through or no fusion defects. It has always been a difficult point in welding.

[0072] According to conventional welding knowledge, burn-through means either reducing the wire feed speed or increasing the welding speed, while incomplete root fusion means either increasing the wire feed speed or decreasing the welding speed—these are contradictory. In addition to wire feed speed and welding speed, welding involves multiple parameters such as torch pointing deviation, torch tilt angle, welding side tilt angle, weld extension, arc length, inductance, pulse frequency, pulse peak value, and workpiece placement angle (uphill or downhill), each with multiple parameter levels. Single-parameter factors can yield conclusions through a limited number of experiments. However, as the number of parameters increases, relying solely on manual experimentation becomes impossible, costly, and unacceptable.

[0073] Therefore, the welding process described in this application aims at the internal fusion size and weld appearance quality of the weld. It uses linear regression and variance models to evaluate the main parameter factors and interaction relationships, performs data analysis, and obtains the optimal parameter combination in step S1 above.

[0074] The method in step S1 above solves the defects of incomplete fusion and burn-through at the root of the weld in thick plates with different aluminum alloys, and can improve the weld quality by more than 40%.

[0075] like Figure 3 As shown, preferably, the welding process further includes:

[0076] Step S2: Weld the front beam 40, middle beam 50 and rear beam 60 to the longitudinal beam welding sub-assemblies respectively to form the front subframe frame welding assembly.

[0077] Clean the parts to be welded before welding, heat the aluminum welding wire to 50°C to 65°C, and preheat the thick plate to 90°C to 120°C before welding.

[0078] The parts to be welded are rotated horizontally by 90°, with the rear support below and the rear beam above, for welding.

[0079] Preferably, in step S2, the welding torch is offset from the rear support by 1.0-2.0 mm, the forward tilt angle is 0-8°, the side tilt angle is 60-80°, the welding speed is 60-80 cm / min, and the wire feeding speed is 9-11 m / min.

[0080] More preferably, in step S2, the arc length of the welding is -8 / -18, and the inductance is 0-10.

[0081] Currently, one of the challenges in welding dissimilar aluminum alloys, AlSi7Mg0.3 (cast aluminum) and 6082-T6 (extruded aluminum), is the tendency for porosity to form in the weld, which reduces weld strength. Aluminum oxidizes very easily, forming a dense oxide film (Al2O3) on the material surface. This oxide film has a melting point of 2050℃, far exceeding the melting point of aluminum (660℃).

[0082] Therefore, welding requires a high current to break down the oxide film, but this can lead to burn-through, especially when the base material is thin. The oxide film also readily absorbs moisture, resulting in defects such as hydrogen porosity.

[0083] In this step, the weld between the rear support and the central beam exhibited numerous pores, with individual pore diameters exceeding 2.0 mm and displaying a honeycomb-like pattern, failing to meet quality requirements. The primary solution to aluminum welding porosity is to use 99.999% pure argon as the shielding gas and increase its flow rate, but these measures were ineffective in this process. Secondly, cleaning the parts before welding to remove oil and moisture, heating the aluminum welding wire (50-65℃) to keep it dry and prevent moisture absorption, and preheating thick plates (90-120℃) provided some relief but did not fundamentally solve the problem. Finally, parameters such as wire feed speed, welding speed, welding torch pointing offset, welding torch tilt angle, welding side tilt angle, wire extension, arc length, inductance, and workpiece placement angle (uphill or downhill) were analyzed using linear regression and variance models to assess the main parameter factors and their interactions, aiming at the weld's internal fusion dimensions and weld appearance quality. This data analysis yielded the optimal parameter combination for step S2.

[0084] Furthermore, in step S2 described here, the diameter of the welded pores is preferably less than 1.0 mm. This method eliminates honeycomb-like pores, meets quality requirements, and fundamentally solves the welding pore defects in dissimilar aluminum differential thickness plates (2.5+10 mm).

[0085] like Figure 4 As shown, more preferably, the welding process further includes:

[0086] Step S3: The first front subframe frame welding assembly is welded to the stabilizer bar bracket 70, the left steering gear bracket 80, the right steering gear bracket 90, the rear suspension beam 100 and the front suspension bracket 110 to form the second front subframe frame welding assembly.

[0087] The welding process begins with the arc starting at both ends and ends in the middle. The arc introduction length is 5-15mm, the arc introduction angle is 90-110°, and the weld overlap at the middle arc end is 10-20mm.

[0088] Here, the initial weld arrangement of the steering gear bracket involved welding the contact edges of two parts in a single pass, without any arc initiation or termination length. During the fatigue test of the steering gear frame, weld cracking occurred at only 65% ​​of the lifespan, leading to frame failure. Failure analysis revealed that the crack started at the weld termination point and extended to the longitudinal and rear beam materials, with a crack length of 9-12 mm, primarily due to the failure to release welding stress in a timely manner. Based on the magnitude, direction, and frequency of the load force, the weld location and length were simulated and calculated. The concepts of "weld initiation length and initiation angle" were added, resulting in a significant improvement in the frame fatigue performance, achieving a crack-free improvement of 3.4 times.

[0089] The initial weld arrangement of the suspended rear beam was to weld the contact edge of the two parts, with only the second weld B and the third weld. Each weld was formed in one go, without the first weld and without the introduction and extension length for arc initiation and termination. When the part was subjected to 24-channel bench performance fatigue test, the weld cracked and the bench failed when the life was only 37%.

[0090] Failure analysis revealed that the crack started at the arc initiation point of the second weld and extended into the rear beam material, with a crack length of 20-30 mm. This was primarily caused by the failure to release welding stress in a timely manner. Simultaneously, the absence of a weld seam at the first weld, under Z-axis load, created a vibration gap, which strained the second weld B, accelerating its failure. Positive thinking included increasing the weld seam A at the first weld seam to avoid the strain from the vibration gap, and welding the welds with high stress (first, second, and third welds) first. Conversely, negative thinking involved avoiding welding at areas of high stress and shortening weld seams to reduce stress.

[0091] This design defines the welding process for the suspended rear beam in this application. The welding sequence is the first weld A, the second weld B, and the third weld C, with the left and right welds being symmetrical.

[0092] Therefore, the weld formed by welding each part in step S3 includes a first weld A, a second weld B, and a third weld C. The arc initiation length of the first weld A is 10-20 mm, the arc initiation angle is 80-100°, and the arc termination gap is 5-10 mm. The second weld B has an arc initiation in the middle and termination at both ends, with a 10-20 mm interval between the two arc initiations and a 5-15 mm gap at the two arc terminations. The third weld C has an arc initiation at both ends and termination in the middle, with an arc initiation length of 10-20 mm, an arc initiation angle of 130-150°, and a 10-20 mm overlap at the middle arc termination. This weld structure significantly improves the fatigue performance of the test bench by 3.4 times without cracking.

[0093] like Figure 5 As shown, preferably, the welding process further includes:

[0094] Step S4: The second front subframe frame welding assembly is welded to the left control arm bracket 120, the right control arm bracket 130, the rear suspension bracket 140, the left reinforcing plate 150, the right reinforcing plate 160 and the front suspension beam 170 to form the third front subframe frame welding assembly.

[0095] The initial weld arrangement of the control arm bracket was to weld the contact edges of the two parts, forming the weld in one go, without any arc initiation or termination length. When the part was subjected to a 12-channel bench performance fatigue test, the weld cracked and the bench failed when the lifespan was only 58.5%.

[0096] Failure analysis revealed that the cracks started at the weld termination point and extended into the longitudinal beam material, with a crack length of 6-25 mm. This was primarily caused by the failure to release welding stress in a timely manner. Based on the magnitude, direction, and frequency of the load, the weld location and length were simulated and calculated. The concepts of "weld introduction length and introduction angle" were introduced, and a new welding process for the control arm support was designed.

[0097] Preferably, the arc begins at both ends and ends and ends at the middle two-thirds of the length, with an arc initiation length of 30-50mm and an arc initiation angle of 135-155°. The weld overlap at the arc termination point is 10-20mm. This weld structure significantly improves the fatigue performance of the test bench by 3.4 times without cracks.

[0098] like Figure 6 As shown, the welding process further includes:

[0099] Step S5: The front subframe frame welding assembly 3 is welded to the right suspension bracket 180 to form the front subframe welding assembly.

[0100] In summary, this invention, applied to the welding process of automotive aluminum alloy front subframes, overcomes challenges such as welding dissimilar aluminum alloys, welding aluminum alloys of varying thicknesses, root incomplete fusion, and porosity through innovative aspects including workpiece posture, welding torch tilt angle, welding process parameters, and weld arrangement. This significantly improves weld quality, enhances weld strength, reduces joint stress, increases bench fatigue life by 3.4 times, and boosts production efficiency. It can be widely applied to the welding process of aluminum alloy chassis for new energy vehicles.

[0101] For those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0102] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0103] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A welding process for an automotive aluminum alloy front subframe, characterized by, The welding process comprises the following steps: S1, welding the rear support, the longitudinal beam and the front tower to form a longitudinal beam welding sub-assembly; during the welding process, the clamp is rotated by 90°, so that the weld joint of the rear support and the longitudinal beam is in a horizontal position; The pointing of the welding gun is offset by 1.0-2.0mm from the rear support, the front inclination angle is 5-15°, the side inclination angle is 60-70°, the welding speed is 60-75cm / min, and the wire feeding speed is 8-10m / min; S2, welding the front beam, the middle beam and the rear beam with the longitudinal beam welding sub-assembly to form a front subframe frame welding assembly one; The parts to be welded are cleaned before welding, the aluminum welding wire is heated at 50-65°C, and the thick plate is preheated at 90-120°C before welding; the parts to be welded are rotated horizontally by 90°, the rear support is at the bottom, and the rear beam is at the top for welding; S3, welding the front subframe frame welding assembly one with the stabilizer bar support, the steering engine support left, the steering engine support right, the suspended rear beam and the front suspension support to form a front subframe frame welding assembly two; The welding starts from both ends to the middle, the arc introduction length is 5-15mm, the arc introduction angle is 90-110°, and the weld joint at the middle is overlapped by 10-20mm; S4, welding the front subframe frame welding assembly two with the control arm support left, the control arm support right, the rear suspension support, the left and right reinforcing plates and the suspended front beam to form a front subframe frame welding assembly three; The welding starts from both ends to the middle 2 / 3 length, the arc introduction length is 30-50mm, the arc introduction angle is 135-155°, and the weld joint at the middle is overlapped by 10-20mm; S5, welding the front subframe frame welding assembly three with the right suspension support to form a front subframe welding assembly.

2. The welding process for an automotive aluminum alloy front subframe according to claim 1, wherein In the step S2, the pointing of the welding gun is offset by 1.0-2.0mm from the rear support, the front inclination angle is 0-8°, the side inclination angle is 60-80°, the welding speed is 60-80cm / min, and the wire feeding speed is 9-11m / min.

3. The welding process for an automotive aluminum alloy front subframe according to claim 2, wherein In the step S2, the gas hole diameter of the welding is less than 1.0mm.

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