High-strength lightweight airbag base and its welding process

Abstract

The present invention discloses a high-strength lightweight airbag base and its welding process, which includes an outer cylinder, an inner cylinder and a bottom plate. The bottom plate is circular, and on the upper surface of the bottom plate, there are concentrically arranged first clamping rings, second clamping rings and third clamping rings with vertical protrusions. Among them, the first clamping ring and the second clamping ring are arranged at the middle position of the radius of the bottom plate. Between the first clamping ring and the second clamping ring is a weld assembly groove, and the bottom end surface of the inner cylinder is vertically clamped in the weld assembly groove. The third clamping ring is close to the edge of the bottom plate, and between the third clamping ring and the edge of the bottom plate is an annular clamping surface. The bottom of the outer cylinder clamps the third clamping ring from the outside, and the bottom end surface of the outer cylinder fits with the annular clamping surface. A filler convex ring is provided on the lower surface of the bottom plate, and the filler convex ring is arranged corresponding to the bottom end surface of the inner cylinder. The airbag base made of high-strength titanium alloy can improve the specific strength of the airbag base material, simplify the complexity of the welding trajectory, and meet the requirements of lightweight and high-strength manufacturing of the product.

Description

Technical Field

[0001] The present invention belongs to the field of automotive parts, and particularly relates to a high-strength lightweight airbag base and its welding process. Background Art

[0002] An automotive suspension is a general term for the force transmission connecting device between the vehicle body or frame and the wheels or axles. Its main function is to transmit the forces and torques between the wheels and the vehicle body, such as supporting force, braking force, and driving force, so as to mitigate the impact load transmitted from the uneven road surface to the vehicle body, attenuate the vibration caused thereby, and ensure the comfort of the occupants, as well as the dynamic load of the goods and the vehicle itself. As an important part of the automotive air suspension system, the air spring bears a large dynamic load and static load. Currently, the materials used to manufacture the airbag base of the air spring are mainly traditional carbon steels such as Q235. With the development of lightweight, the application of aluminum alloy in the airbag base is becoming more and more widespread. However, there are many welding porosity defects in aluminum alloy fusion welding, and the subsequent non-destructive testing and repair welding after the occurrence of porosity defects will increase the complexity of the overall manufacturing process.

[0003] In the selection of welding process, since the tensile strength of high-strength aluminum alloy or Q235 steel is generally between 500 - 600 Mpa, and the strength of common aluminum alloys such as 6061 is even lower (300 MPa). To ensure the effective load of the airbag, when designing the connection parts of the outer cylinder - bottom plate and the column - bottom plate, since this connection part is the welding position, considering the softening effect of welding, in order to ensure the bearing capacity and for the convenience of welding operation, the connection part has to be designed to be relatively thick, and the welding process generally used is wire-filled argon arc welding or gas shielded welding.

[0004] For example Figure 1 In the airbag scheme of a common aluminum alloy shown in [reference], the thickened parts are the welds at the connections of the outer cylinder - bottom plate and the column - bottom plate respectively. It can be seen from the figure that due to the use of common aluminum alloy, the thickness at the outer cylinder - bottom plate is relatively large, and at the same time, the bottom plate presents a cylindrical shape outside. The weld of the outer cylinder - bottom plate is a standard circumferential weld, and the weld connection at the column - bottom plate is also a circumferential weld. A relatively high circumferential step is designed for both welds, and its main purpose is to ensure the bearing capacity. As the main load-bearing airbag base, its thickness is distributed between 8 - 10 mm. To ensure full penetration welding, traditional wire-filled argon arc welding is mainly used. This also fully shows that the airbag base made of traditional high-strength aluminum alloy and Q235 steel not only fails to achieve the purpose of weight reduction and lightweight, but also is very limited in terms of the structural scheme and welding process scheme of the airbag.

[0005] Generally speaking, for materials with a relatively large thickness, beveling is usually adopted, and multi-layer and multi-pass wire filling welding is carried out. The processing efficiency is low, and porosity defects are likely to occur, affecting the sealing performance of the product. Therefore, when using ordinary aluminum alloy materials, it is impossible to reduce the material thickness while ensuring the overall rigidity, and the high strength and light weight requirements of the airbag base cannot be met simultaneously. Summary of the Invention

[0006] In view of the above problems and technical requirements, the present invention provides a high-strength and lightweight airbag base and its welding process. It uses high-strength titanium alloy as the material of the airbag base to improve the specific strength of the airbag base material, and simplifies the complexity of the welding trajectory by optimizing the design of the airbag base structure. On the premise of ensuring the product strength, the lightweight manufacturing of the product is further realized.

[0007] The technical solution of the present invention is as follows: A high-strength and lightweight airbag base includes an outer cylinder, an inner cylinder and a bottom plate. The bottom plate is circular, and on the upper surface of the bottom plate, there are concentrically arranged first clamping rings, second clamping rings and third clamping rings which are vertically convex. Among them, the first clamping ring and the second clamping ring are arranged at the middle position of the bottom plate radius. Between the first clamping ring and the second clamping ring is a weld assembly groove. The bottom end surface of the inner cylinder is vertically clamped in the weld assembly groove. The third clamping ring is close to the edge of the bottom plate. Between the third clamping ring and the bottom plate edge is an annular clamping surface. The bottom of the outer cylinder is clamped to the third clamping ring from the outside, and the bottom end surface of the outer cylinder is attached to the annular clamping surface; on the lower surface of the bottom plate, there is a filler convex ring which is correspondingly arranged with the bottom end surface of the inner cylinder. The weld assembly groove formed between the first clamping ring and the second clamping ring facilitates the insertion and pre-fixation of the inner cylinder. The filler convex ring arranged on the back of the weld assembly groove can not only mark the welding position but also supplement welding materials during the subsequent laser welding process, eliminating the need for manual wire filling welding; the third clamping ring and the annular clamping surface facilitate the assembly of the outer cylinder on the bottom plate edge and pre-fix the outer cylinder. The concentric arrangement of the first clamping ring, the second clamping ring and the third clamping ring makes the assembled inner cylinder and outer cylinder also have the same center.

[0008] Furthermore, on the circumferential surface of the outer cylinder, there are at least three circles of reinforcing layer structures along the length direction. The reinforcing layers are outwardly convex arcs, and the reinforcing layers are equidistantly spaced. The multiple curled structures are equivalent to the function of reinforcing ribs and can increase the overall compressive and buckling resistance of the outer cylinder structure.

[0009] Furthermore, the bottom plate is an integrally formed part. At the center of the bottom surface of the bottom plate, there is a downwardly convex assembly column, and the cross-section of the bottom plate is arc-shaped.

[0010] Further, the first snap ring, the second snap ring, and the third snap ring are all upward rectangular protrusions, and the packing convex ring is a downward arc-shaped protrusion. The first snap ring, the second snap ring, and the third snap ring are to clamp and fix the inner cylinder and the outer cylinder. Setting them as rectangles has a better clamping effect. And the packing convex ring is set as an arc. When laser welding, the packing convex ring melts from the middle and fills inward, and melts on both sides and fills towards the middle. After welding, the position of the packing convex ring is relatively flat without overly prominent welding scars.

[0011] Further, the thickness of the bottom plate is 2 - 3 mm.

[0012] Further, the inner cylinder, the outer cylinder, and the bottom plate are all formed by titanium alloy. The chemical composition of the titanium alloy is Ti - 4Al - 3Cr - 2V - 3Mo - 2Fe. By mass fraction, the Al content is 3.6 - 4.6%, the Cr content is 2.5 - 3.5%, the V content is 1.5 - 2.5%, the Mo content is 2.5 - 3.5%, the Fe content is 1.5 - 2.2%, and the balance is Ti. Compared with ordinary aluminum alloy and Q235 steel, under the condition of unchanged bearing load, the specific strength of the titanium alloy is higher than that of the aluminum alloy and Q235 steel. The thickness of the bottom plate made of titanium alloy will be significantly reduced. The thickness of the titanium alloy bottom plate is only 2 - 3 mm. This thickness is suitable for the penetration pulsed laser autogenous welding process to weld the bottom plate with the inner cylinder and the outer cylinder together.

[0013] The welding process of the high-strength lightweight airbag base includes the following steps:

[0014] Step1: Place the bottom plate horizontally, insert the bottom end face of the inner cylinder into the bottom of the weld assembly groove, and tightly surround the third snap ring with the outer cylinder and insert it until it fits with the annular clamping surface.

[0015] Step2: Perform welding by pulsed laser autogenous welding. The laser is vertically upward and aligned with the packing convex ring, and weld along the packing convex ring. The laser penetrates the bottom plate, melts the packing convex ring and fills upward to supplement the material loss during the welding process, and weld the inner cylinder and the bottom plate together.

[0016] Step3: Align the laser from the lower surface of the bottom plate with the annular clamping surface and weld around the edge of the bottom plate. The laser penetrates the bottom plate and welds the bottom end face of the outer cylinder with the annular clamping surface. After the edge of the lower surface of the bottom plate melts, supplement the material for the welding surface.

[0017] The advantages of using the laser penetration welding process are as follows: The weld track is a circular track that is approximately a plane. By using a robot or a machine tool to drive the laser welding head, the welding can be completed without the cooperation of mechanisms such as a positioner. It has the advantages of stable welding quality, small welding deformation, and small residual stress.

[0018] Furthermore, the pulse energy of the pulsed laser autogenous welding is 5 - 12 J, the pulse time is 5 - 10 milliseconds, the welding speed is 5 mm / s, the spot diameter is 0.65 mm, and the defocus distance is -2 mm.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The airbag base is made of titanium alloy material. The specific strength of titanium alloy is higher than that of aluminum alloy and Q235 steel. Under the same load, the thickness of the base plate made of titanium alloy can be reduced to 2 - 3 mm, and this thickness is suitable for penetration welding by pulsed laser autogenous welding; 2) Compared with the traditional tungsten inert gas welding with filler wire, laser welding can use a robot or a machine tool to drive the laser welding head for automatic penetration welding, with stable welding quality, small welding deformation, and small residual stress; 3) Three snap rings are used to clamp the outer cylinder and the inner cylinder respectively to ensure accurate positioning before welding. The good pre-fixing effect is conducive to the progress of automatic welding; 4) The filler convex ring on the back of the weld can not only mark the welding position, but also the protruding design can effectively supplement the burn loss of the titanium alloy material during the welding process, and play a reinforcing role in compensating for the decline in the mechanical properties of the material caused by the welding process. Description of the Drawings

[0020] Figure 1 is a welding schematic diagram of the airbag solution of ordinary aluminum alloy in the prior art;

[0021] Figure 2 is a three-dimensional structure diagram of the high-strength and lightweight airbag base of the present invention;

[0022] Figure 3 is a cross-sectional schematic diagram of the high-strength and lightweight airbag base of the present invention;

[0023] Figure 4 is a connection schematic diagram of the inner cylinder and the base plate in the present invention;

[0024] Figure 5 is a connection schematic diagram of the outer cylinder and the base plate in the present invention;

[0025] The markings in the figure are: outer cylinder 1, reinforcing layer structure 11, inner cylinder 2, base plate 3, first snap ring 31, second snap ring 32, third snap ring 33, weld assembly groove 34, annular clamping surface 35, filler convex ring 36, assembly post 37. Detailed Embodiments

[0026] The following further describes the present invention with reference to the drawings and embodiments.

[0027] As Figure 2-5 shown, the high-strength and lightweight airbag base of the present invention includes an outer cylinder 1, an inner cylinder 2, and a base plate 3. The base plate 3 is a circular integrally formed part. An assembly post 37 protruding downward is provided at the center of the bottom surface of the base plate 3, and the cross-section of the base plate 3 is arc-shaped.

[0028] On the upper surface of the bottom plate 3, there are vertically protruding and concentrically arranged first clamping ring 31, second clamping ring 32 and third clamping ring 33. Among them, the first clamping ring 31 and the second clamping ring 32 are arranged at the middle position of the radius of the bottom plate 3. Between the first clamping ring 31 and the second clamping ring 32 is a weld assembly groove 34, and the bottom end surface of the inner cylinder 2 is vertically clamped in the weld assembly groove 34. The weld assembly groove 34 formed between the first clamping ring 31 and the second clamping ring 32 facilitates the insertion and pre-fixation of the inner cylinder 2. The filler convex ring 36 arranged on the back of the weld assembly groove 34 can not only mark the welding position but also supplement welding materials during the subsequent laser welding process, eliminating the need for manual wire filling welding.

[0029] The third clamping ring 33 is close to the edge of the bottom plate 3. Between the third clamping ring 33 and the edge of the bottom plate 3 is an annular clamping surface 35. The bottom of the outer cylinder 1 is clamped to the third clamping ring 33 from the outside, and the bottom end surface of the outer cylinder 1 is attached to the annular clamping surface 35. The third clamping ring 33 and the annular clamping surface 35 facilitate the assembly of the outer cylinder 1 on the edge of the bottom plate 3 and pre-fix the outer cylinder 1. The concentric arrangement of the first clamping ring 31, the second clamping ring 32 and the third clamping ring 33 makes the assembled inner cylinder 2 and outer cylinder 1 also have the same center. Preferably, the first clamping ring 31, the second clamping ring 32 and the third clamping ring 33 are all upward rectangular protrusions, and the rectangular protrusions have a better clamping effect on the inner cylinder 2 and the outer cylinder 1.

[0030] On the lower surface of the bottom plate 3, there is a filler convex ring 36. The filler convex ring 36 is arranged corresponding to the bottom end surface of the inner cylinder 2. The filler convex ring 36 is a downward arc-shaped protrusion. By setting the filler convex ring 36 as an arc shape, when laser welding, the filler convex ring 36 melts and fills inward from the middle, and melts and fills towards the middle on both sides. After welding, the position of the filler convex ring 36 is relatively flat without overly prominent welding scars.

[0031] On the circumferential surface of the outer cylinder 1, there are at least three circles of reinforcing layer structures 11 arranged along the length direction. The reinforcing layers are outward convex arcs, and the reinforcing layers are arranged at equal intervals. The multiple curling structures are equivalent to the function of reinforcing ribs, which can increase the overall compressive and buckling resistance of the structure of the outer cylinder 1.

[0032] The thickness of the bottom plate 3 is 2 - 3 mm. The inner cylinder 2, the outer cylinder 1 and the bottom plate 3 are all made of titanium alloy. The chemical composition of the titanium alloy is Ti - 4Al - 3Cr - 2V - 3Mo - 2Fe. By mass fraction, the Al content is 3.6 - 4.6%, the Cr content is 2.5 - 3.5%, the V content is 1.5 - 2.5%, the Mo content is 2.5 - 3.5%, the Fe content is 1.5 - 2.2%, and the balance is Ti.

[0033] The welding process of the high-strength lightweight airbag base includes the following steps:

[0034] Step1: Horizontally place the bottom plate 3, insert the bottom end face of the inner cylinder 2 into the bottom of the weld assembly groove 34, and closely surround the third snap ring 33 with the outer cylinder 1 and insert it until it fits with the annular clamping surface 35;

[0035] Step2: Perform welding using pulsed laser autogenous welding. The laser is vertically upward and aligned with the filler boss 36, and weld along the filler boss 36. The laser penetrates the bottom plate 3, melts the filler boss 36 and fills upward to supplement the material loss during the welding process, and welds the inner cylinder 2 and the bottom plate 3 together;

[0036] Step3: Align the laser from the lower surface of the bottom plate 3 with the annular clamping surface 35 and weld around the edge of the bottom plate 3. The laser penetrates the bottom plate 3 and welds the bottom end face of the outer cylinder 1 to the annular clamping surface 35. After the edge of the lower surface of the bottom plate 3 is melted, supplement the material to the welding surface.

[0037] During the penetration welding process of pulsed laser autogenous welding, the pulse energy of the pulsed laser autogenous welding is 5 - 12 J, the pulse time is 5 - 10 milliseconds, the welding speed is 5 mm / s, the spot diameter is 0.65 mm, and the defocus distance is -2 mm.

[0038] As described above, only several preferred embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any changes and substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A high-strength lightweight airbag base, characterized in that: It includes an outer cylinder, an inner cylinder and a bottom plate. The bottom plate is circular. On the upper surface of the bottom plate, there are concentrically arranged first, second and third clamping rings which are vertically raised. Among them, the first and second clamping rings are arranged at the middle position of the radius of the bottom plate. Between the first and second clamping rings is a weld assembly groove. The bottom end face of the inner cylinder is vertically clamped in the weld assembly groove. The third clamping ring is close to the edge of the bottom plate. Between the third clamping ring and the edge of the bottom plate is an annular clamping surface. The bottom of the outer cylinder clamps the third clamping ring from the outside, and the bottom end face of the outer cylinder fits with the annular clamping surface. The inner cylinder, the outer cylinder and the bottom plate are all formed by titanium alloy material. The chemical composition of the titanium alloy is Ti-4Al-3Cr-2V-3Mo-2Fe. By mass fraction, the Al content is 3.6-4.6%, the Cr content is 2.5-3.5%, the V content is 1.5-2.5%, the Mo content is 2.5-3.5%, the Fe content is 1.5-2.2%, and the balance is Ti. On the lower surface of the bottom plate, there is a packing convex ring which is arranged corresponding to the bottom end face of the inner cylinder. Pulse laser autogenous welding is used for welding. The laser is vertically upward and aligned with the packing convex ring, and welded along the packing convex ring. The laser penetrates the bottom plate, melts the packing convex ring and fills it upward to supplement the material loss during the welding process, and welds the inner cylinder and the bottom plate together.

2. The high-strength and lightweight airbag base according to claim 1, wherein: On the circumferential surface of the outer cylinder, there are at least three circles of reinforcing layer structures arranged along the length direction. The reinforcing layers are outwardly convex arcs, and the reinforcing layers are arranged at equal intervals.

3. The high-strength and lightweight airbag base according to claim 2, characterized in that: The bottom plate is an integrally formed part. At the center of the bottom surface of the bottom plate, there is an upwardly raised assembly post, and the cross-section of the bottom plate is an arc.

4. The high-strength and lightweight airbag base according to claim 3, wherein: The first, second and third clamping rings are all upward rectangular protrusions, and the packing convex ring is a downward arc-shaped protrusion.

5. The high-strength and lightweight airbag base according to claim 1, wherein: The thickness of the bottom plate is 2-3 mm.

6. The welding process of the high-strength and lightweight airbag base according to claim 1, characterized in that: It includes the following steps: Step1: Place the bottom plate horizontally, insert the bottom end face of the inner cylinder into the bottom of the weld assembly groove, and the outer cylinder closely surrounds the third clamping ring and inserts it until it fits with the annular clamping surface. Step2: Use pulse laser autogenous welding for welding. The laser is vertically upward and aligned with the packing convex ring, and welded along the packing convex ring. The laser penetrates the bottom plate, melts the packing convex ring and fills it upward to supplement the material loss during the welding process, and welds the inner cylinder and the bottom plate together. Step3: The laser is aligned with the annular clamping surface from the lower surface of the bottom plate and welded around the edge of the bottom plate. The laser penetrates the bottom plate, welds the bottom end face of the outer cylinder and the annular clamping surface together, and supplements the material to the welding surface after the edge of the lower surface of the bottom plate is melted.

7. The welding process of the high-strength lightweight airbag base according to claim 6, characterized in that: The pulse energy of the pulse laser autogenous welding is 5-12 J, the pulse time is 5-10 milliseconds, the welding speed is 5 mm / s, the spot diameter is 0.65 mm, and the defocusing distance is -2 mm.

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