Laser wire welding device and method

Abstract

A laser wire-filling welding device comprises a laser head connected to a laser source and outputting laser light, and a wire guide head connected to a wire feeding mechanism and outputting welding wire. The output of laser light from the laser head and the output of welding wire from the wire guide head are controlled in time by feedback regulation, that is, the laser wire-filling welding device comprises a detection mechanism. The feedback regulation detects the position through the detection mechanism and adjusts the position of the welding wire and the focusing spot of the laser beam and the output timing of the welding wire and the laser beam. The wire is continuously fed before and after the welding starts and ends, respectively, to solve the problems of gaps and poor connections caused by insufficient filling metal.

Description

Technical Field

[0001] The invention belongs to the field of welding, and in particular relates to a laser wire-filling welding device and a welding method. Background Art

[0002] Laser wire welding is a welding method that uses laser energy to melt the filler wire, and at the same time, the laser energy melts the material body. The molten wire and the material body are mixed to form a molten pool, which is cooled and solidified to form a weld. In practical applications, the start and end positions of the welding combination are usually located at the edge of the workpiece. When the laser beam acts on the above two positions, due to the flow of the molten pool and the lack of replenishment, gaps usually appear on the edge, which brings problems to the subsequent processing and use of the welded parts. Especially in the application scenario of thin plate butt welding, large gaps are prone to appear due to insufficient filling at the head and tail, such as laser welded plates in the automotive industry. The appearance of gaps at the end of the weld will increase the risk of cracking of parts during subsequent stamping. In steel plates with low matrix strength, due to the phase transformation hardening of the weld, the weld strength is at a high level, and direct laser welding can usually meet the use requirements; however, in steel plates with high matrix strength, such as high-strength steel of 1200MPa and above, the welded weld has a tendency to harden and is prone to cracking. When gaps exist, the risk of cracking will be aggravated. Another example is hot-formed steel, whose matrix strength after hot stamping can reach 1500MPa. The notch at the end of the weld can also cause cracking of the weld during stamping or subsequent use. Especially for hot-formed steel, the notch may become a weak position for hydrogen embrittlement cracking, which is not conducive to long-term storage. In practical applications, the weld at the notch is usually cut off. This is also an important application area of ​​laser cutting in the automotive industry, that is, the hot-stamped parts are cut and removed including the head and tail of the weld. In addition, when there is aluminum or aluminum-based coating on the surface of hot-pressed steel, the impact is even greater, because the presence of the coating itself increases the difficulty of obtaining qualified weld formation and weld strength. Summary of the invention

[0003] The purpose of the present invention is to provide a laser wire-filling welding device and a welding method to achieve effective filling of the head and tail parts of the weld, avoid defects such as gaps, make the head and tail parts of the weld shape equivalent to the middle of the weld, and ensure the consistency of the weld quality.

[0004] The laser wire welding device of the present invention has the following characteristics:

[0005] It includes a laser head connected to a laser source and outputting a laser beam, and a wire head connected to a wire feeding mechanism and outputting a welding wire. The position and time at which the laser head outputs the laser beam and the wire head outputs the welding wire are controlled by a feedback adjustment system. The feedback adjustment control process includes:

[0006] At a position Xm in front of the welding start position of the workpiece to be welded, the laser head outputs the laser beam in advance, the wire head outputs the welding wire in advance at a speed V1, and the laser beam acts on the welding wire until it reaches the welding start position X1 of the workpiece to be welded; the wire head outputs the welding wire at a speed V0 until it reaches the welding end position X2 of the workpiece to be welded; the wire head outputs the welding wire at a speed V2, and the laser head continues to output the laser beam, so that the laser beam acts on the welding wire until it reaches the position Xn behind the welding end position of the workpiece to be welded;

[0007] The distance S1 from Xm to X1 satisfies the following relationship: S1 = (3.5-5.5)*V0*D / (π*r 2 *V1);

[0008] The distance S2 from X2 to Xn satisfies the following relationship: S2 = (2.5-4.5)*V0*D / (π*r 2 *V2);

[0009] In the above relationship, D is the average plate thickness of the workpiece combination to be welded, which ranges from 1.0 to 3.2 mm; r is the radius of the welding wire used, which ranges from 0.4 to 0.8 mm;

[0010] Preferably, the welding wire output speeds V0, V1 and V2 satisfy the following relationship:

[0011] V1=(0.4~0.8)*V0, V2=(0.4~0.8)*V0.

[0012] In a preferred example, before the welding start position, the laser head outputs the laser beam in advance and the wire guide head outputs the welding wire in advance by 0.1 to 0.5 seconds; after the welding end position, the laser head delays the output of the laser beam and the wire guide head delays the output of the welding wire by 0.1 to 0.5 seconds.

[0013] In another preferred example, the laser wire welding device also includes a displacement adjustment mechanism, which adjusts the position of the laser head according to the thickness of the workpiece to be welded and the requirements for defocusing and focusing of the laser beam; then adjusts the position of the wire guide head so that the end of the output welding wire is located in the spot of the laser beam acting on the upper surface of the workpiece to be welded when it contacts the upper surface of the workpiece to be welded.

[0014] In another preferred example, the laser wire-filling welding device also includes a detection mechanism, which detects in advance the plate thickness of the workpiece combination to be welded, the start and end welding positions, and the relative distance between the laser head and the upper surface of the workpiece to be welded, and the detection data is fed back to the displacement adjustment mechanism to adjust the position of the laser head and the wire guide head; and fed back to the control system to adjust the advance or delay output of the laser beam and the welding wire.

[0015] A laser wire-filling welding method comprises the following steps:

[0016] Inputting laser parameters into the welding control system, including the laser beam defocus amount;

[0017] Input the plate thickness data of the workpiece combination to be welded, or obtain the plate thickness data through the detection agency;

[0018] The detection mechanism detects the welding start position in advance and calculates the position Xm ahead of the welding start position;

[0019] The laser beam is output at Xm, and the welding wire is output at a speed V1, so that the laser beam acts on the welding wire until it reaches the welding start position X1 of the workpiece to be welded;

[0020] The welding wire is output at a speed V0, and the laser beam acts partially on the welding wire and partially on the workpiece to be welded until the welding end position X2 of the workpiece to be welded is reached;

[0021] The welding wire is output at a speed V2, and the laser beam acts on the welding wire until it reaches a position Xn behind the welding end position of the workpiece to be welded;

[0022] In the above process, the laser beam and the workpiece to be welded maintain relative motion at a welding speed V;

[0023] The distance S1 from Xm to X1 satisfies the following relationship: S1 = (3.5-5.5)*V0*D / (π*r 2 *V1);

[0024] The distance S2 from X2 to Xn satisfies the following relationship: S2 = (2.5-4.5)*V0*D / (π*r 2 *V2);

[0025] In the above relationship, D is the average plate thickness of the workpiece combination to be welded, and r is the radius of the welding wire used;

[0026] Preferably, the welding wire output speeds V0, V1 and V2 satisfy the following relationship:

[0027] V1=(0.4~0.8)*V0, V2=(0.4~0.8)*V0.

[0028] In a preferred example, the workpiece combination to be welded is a butt-welded combination, and the average plate thickness D of the butt-welded plates ranges from 1.0 to 3.2 mm; the radius r of the welding wire used ranges from 0.4 to 0.8 mm.

[0029] In another preferred example, the matrix of the workpiece to be welded or the matrix after heat treatment has a tensile strength of not less than 1200 MPa, and there is an aluminum or aluminum-based coating on the matrix surface. The workpieces to be welded are butt-welded. The mass percentage content of alloying elements in the welding wire at least satisfies the following relationships: 0.1% < C < 0.2% < Si < 1.2% < Mn < 3% < Ni, 2% < Cr + Mo < 4%, and 8% < Cr + Mo + Ni < 15%. In the butt-welding without a welding gap, the values of the wire feeding speed V0, the welding speed V, and the combined average plate thickness D of the workpieces to be welded satisfy the relationship: V0 = (0.8 - 1.1) * (D - 0.8) * V.

[0030] Preferably, the mass percentage content of alloying elements in the welding wire also includes: 0.5% - 1.5% of Cu, 0.05% - 0.1% of Ti, and multiple or all of Nb, W, B, and V with a content of 0.001% - 0.006%. The contents of P and S are both controlled within 0.008%.

[0031] The present invention has the following technical effects: 1) Solve the problems of insufficient filling such as collapse and notch caused by material loss at the starting and ending positions of the welding of the sheet metal edge; 2) Solve the problems of the lack in the weld length direction or the discontinuous connection of the two butted plates at the weld ends of the automotive laser tailor-welded blanks, i.e., the starting and ending positions of the welding, to ensure the continuous, uniform, and effective connection of the entire weld and avoid cracking caused by the head and tail during the stamping of the weld; 3) Use the welding wire and the wire filling ratio (the ratio parameter of the wire feeding speed to the welding speed for different plate thicknesses) provided by the technical solution of the present invention to achieve good forming at the beginning and end of the butt-welded seams of ultra-high strength steels of 1200 MPa and above, including hot stamping steels with aluminum or aluminum-based coatings, and ensure that the weld reinforcement requirements in the case of butt-welding without a gap meet the industrial requirements. At the same time, suppress the adverse effects of the aluminum element in the coating, meet the joint strength requirements, that is, the tensile joint fractures in the base material; 4) Under the given welding parameter conditions, such as the wire feeding time in advance and in delay of 0.1 - 0.5 s, and the wire feeding speed in advance and in delay being 40% - 80% of the normal wire feeding speed, it can ensure that there is sufficient molten filling metal at the weld ends to meet the connection of the butted plates, and at the same time, it will not form excessive metal accumulation or protrusion; 5) Reduce or eliminate a large amount of cutting loss at the starting and ending positions of the weld seams. Description of the Drawings

[0032] Figure 1 It is a welding schematic diagram of a laser wire filling welding device;

[0033] Figure 2 It is a schematic diagram of the notch at the end of a conventional thin plate welding;

[0034] Figure 3 It is a photo of the unconnected end of the existing technology of actual laser wire filling and welding;

[0035] Figure 4 The photo of the well-formed weld end is obtained by the technology of the present invention;

[0036] Figure 5 This is a photo of the tensile fracture of 1500MPa aluminum-silicon coated hot-formed steel welded according to this technical solution.

[0037] Notes in the figure: 1 is a laser head, 11 is a laser beam, 12 is a component connected to the laser source, 2 is a wire guide head, 21 is a welding wire, 22 is a component connected to a wire feeding mechanism, 3 is a welding position detection mechanism, 31 is an angle adjustment mechanism, 32 is an XY position adjustment mechanism, 33 is a Z position adjustment mechanism, 4 is a workpiece to be welded, and 41 is a butt welding area.

[0038] The purpose of the above drawings is to describe the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0040] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0041] like Figure 1 As shown, it is a schematic diagram of a laser wire welding device and its butt welding, the device includes a laser head 1 and a wire head 2, the laser head 1 is connected to the laser source through a component 12, and outputs a laser beam 11, the wire head 2 is connected to the wire feeding mechanism through a component 22, and outputs a welding wire 21. In the figure, the laser beam 11 and the workpiece 4 to be welded move relative to each other in the positive direction of the X-axis, that is, the left side of the butt welding area 41 is the welding start position X1, and the right side is the welding end position X2. The welding position detection mechanism 3 can detect the butt welding area 41 in advance and identify the welding start and end positions. The feedback adjustment system and the displacement adjustment mechanism 31~33 can adjust the relative position of the laser head and the wire guide head in XYZ to meet the needs of different parameter adjustments, such as different laser beam defocus amounts, different welding wire output angles, etc. The key to the adjustment is: when the end of the welding wire 21 is located on the upper surface of the thicker workpiece 4 to be welded, it is also located in the spot where the laser beam 11 acts on the upper surface of the thicker workpiece 4 to be welded, that is, part of the laser beam acts on the welding wire, and part of it acts on the workpiece to be welded.

[0042] Example 1

[0043] The welding position detection mechanism 3 detects the welding start position X1 of the butt welding area 41 in advance. According to the welding speed V and the advance wire feeding speed V1 set in advance, at the Xm position before the welding wire 21 reaches the welding start position, the laser beam 11 and the welding wire 21 are output respectively. Within 0.1 to 0.5 seconds, the laser beam 11 and the welding wire 21 reach the welding start position X1, and the welding wire melted in advance enters the butt welding area 41, which supplements the lack of end filling metal in the subsequent normal welding process, and obtains good end forming. Subsequently, the welding position detection mechanism 3 detects the welding end position X2 of the butt welding area 41 in advance. According to the welding speed and the delayed wire feeding speed V2 set in advance, 0.1 to 0.5 seconds after the welding wire 21 passes the welding end position, the laser beam 11 and the welding wire 21 are continuously output respectively, and the melted welding wire metal is filled to the end of the welding wire, and the end position of the laser beam is at Xn at this time. Between the welding start position X1 and the welding end position X2, the wire feeding speed is V0.

[0044] Example 2

[0045] According to the scheme of Example 1, the workpiece to be welded is a butt-welded assembly. According to the different average plate thickness D of the assembly, the positions and wire feeding speeds of the advance and retard wire feeding satisfy the following relationship:

[0046] The distance S1 from Xm to X1 satisfies the following relationship: S1 = (3.5-5.5)*V0*D / (π*r 2 *V1);

[0047] The distance S2 from X2 to Xn satisfies the following relationship: S2 = (2.5-4.5)*V0*D / (π*r 2 *V2);

[0048] In the above relationship, D is the average plate thickness of the workpiece combination to be welded, which ranges from 1.0 to 3.2 mm; r is the radius of the welding wire, which ranges from 0.4 to 0.8 mm.

[0049] At the same time, the wire output speeds V0, V1 and V2 satisfy the following relationship:

[0050] V1=(0.4~0.8)*V0, V2=(0.4~0.8)*V0.

[0051] According to the implementation of the above two solutions, the ends of the welds of the tailor-welded plates with a thickness of 1.0 to 3.2 mm can be effectively filled to avoid the formation of gaps.

[0052] Example 3

[0053] Similar to the foregoing embodiments, the difference lies in that the workpiece 4 to be welded is composed of at least one kind of hot-formed steel with an aluminum-silicon coating on the surface, and no butt welding gap is set for the butt joint combination; the mass percentage content of alloying elements in the welding wire used simultaneously satisfies the following relationships: 0.1% < C < 0.2% < Si < 1.2% < Mn < 3% < Ni, 2% < Cr + Mo < 4% and 8% < Cr + Mo + Ni < 15%, 1.0% of Cu, 0.06% of Ti, about 0.004% of Nb, W, P, S; in the butt welding without a butt welding gap, the values of the wire feeding speed V0, the welding speed V, and the average plate thickness D of the workpiece combination to be welded satisfy the relationship:

[0054] V0 = (0.8 - 1.1) * (D - 0.8) * V; After welding using the above scheme, the formed butt weld is uniform and the quality is stable. After the welded part is heated, heat-insulated and stamped, the weld does not crack during the stamping and use processes.

[0055] Figure 4 Shows the effect of achieving effective end connection using the technical scheme of the present invention, with the plate thickness combination of 1.4mm + 2.0mm; Figure 5 Demonstrates the effect that the tensile fracture of the laser wire filling butt welding of aluminum-silicon coated hot-formed steel obtained by using the technical scheme of the present invention, the wire and filling parameters is in the base metal, with the plate thickness combination of 1.5mm + 1.5mm and the matrix strength of the hot-stamped sheet being greater than 1500MPa.

[0056] Comparative example

[0057] If the laser wire filling welding device of the present invention is not adopted, or the wire feeding scheme is advanced or delayed, a notch as shown in Figure 2 will be formed at the weld end, or the butt end connection will be poor as shown in Figure 3 .

[0058] The purpose of the above embodiments is to make further detailed descriptions of the present invention in combination with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the claims of the present invention, optimizing or equivalently replacing the components or methods involved, and combining the implementation manners in different embodiments without conflict in principles all fall within the protection scope of the present invention.

Claims

1. A laser wire welding device, comprising a laser head connected to a laser source and outputting a laser beam, and a wire guide head connected to a wire feeding mechanism and outputting a welding wire, wherein the position and time at which the laser head outputs the laser beam and the wire guide head outputs the welding wire are controlled by a feedback adjustment system, and the feedback adjustment control process comprises: At a position Xm in front of the welding start position of the workpiece to be welded, the laser head outputs the laser beam in advance, the wire head outputs the welding wire in advance at a speed V1, and the laser beam acts on the welding wire until it reaches the welding start position X1 of the workpiece to be welded; the wire head outputs the welding wire at a speed V0 until it reaches the welding end position X2 of the workpiece to be welded; the wire head outputs the welding wire at a speed V2, and the laser head continues to output the laser beam, so that the laser beam acts on the welding wire until it reaches the position Xn behind the welding end position of the workpiece to be welded; The distance S1 from Xm to X1 satisfies the following relationship: S1 = (3.5-5.5)*V0*D / (π*r 2 *V1); The distance S2 from X2 to Xn satisfies the following relationship: S2 = (2.5-4.5)*V0*D / (π*r 2 *V2); In the above relationship, D is the average plate thickness of the combination of workpieces to be welded, which ranges from 1.0 to 3.2 mm; r is the radius of the welding wire used, which ranges from 0.4 to 0.8 mm.

2. The laser wire welding device according to claim 1, characterized in that: The welding wire output speeds V0, V1 and V2 satisfy the following relationship: V1 = (0.4-0.8)*V0, V2 = (0.4-0.8)*V0.

3. The laser welding device with filler wire according to claim 1, characterized in that: Before the welding start position X1, the laser head outputs the laser beam in advance and the wire head outputs the welding wire in advance by 0.1 to 0.5 s; after the welding end position X2, the laser head delays the output of the laser beam and the wire head delays the output of the welding wire by 0.1 to 0.5 s.

4. The laser welding device with filler wire according to claim 1, characterized in that: It also includes a displacement adjustment mechanism, which adjusts the position of the laser head according to the thickness of the workpiece to be welded and the requirement for laser beam defocusing; then adjusts the position of the wire guide head so that the end of the output welding wire is located in the spot of the laser beam acting on the upper surface of the workpiece to be welded when it contacts the upper surface of the workpiece to be welded.

5. The laser wire welding device according to claim 1 or 4, characterized in that: It also includes a detection mechanism, which detects in advance the plate thickness of the combination of workpieces to be welded, the start and end positions of welding, and the relative distance between the laser head and the upper surface of the workpieces to be welded. The detection data is fed back to the displacement adjustment mechanism to adjust the position of the laser head and the wire guide head; and the feedback is fed back to the control system to adjust the advance or delay output of the laser beam and the welding wire.

6. A laser wire welding method, characterized in that the steps include: Inputting laser parameters into the welding control system, including the laser beam defocus amount; Input the plate thickness data of the workpiece combination to be welded, or obtain the plate thickness data through the detection agency; The detection mechanism detects the welding start position in advance and calculates the position Xm ahead of the welding start position; The laser beam is output at position Xm, and the welding wire is output at a speed V1, so that the laser beam acts on the welding wire until it reaches the welding start position X1 of the workpiece to be welded; The welding wire is output at a speed V0, and the laser beam acts partially on the welding wire and partially on the workpiece to be welded until the welding end position X2 of the workpiece to be welded is reached; The welding wire is output at a speed V2, and the laser beam acts on the welding wire until it reaches a position Xn behind the welding end position of the workpiece to be welded; In the above process, the laser beam and the workpiece to be welded maintain relative motion at a welding speed V; The distance S1 from Xm to X1 satisfies the following relationship: S1 = (3.5-5.5)*V0*D / (π*r 2 *V1); The distance S2 from X2 to Xn satisfies the following relationship: S2 = (2.5-4.5)*V0*D / (π*r 2 *V2); In the above relationship, D is the average plate thickness of the workpiece combination to be welded, and r is the radius of the welding wire used.

7. The laser wire welding method according to claim 6, characterized in that: The wire output speeds V0, V1, and V2 satisfy the following relationships: V1 = (0.4 - 0.8) * V0, V2 = (0.4 - 0.8) * V0.

8. The laser wire welding method according to claim 6, characterized in that: The workpiece combination to be welded is a butt welding combination, and the range of the average plate thickness D of the butt plates is 1.0 - 3.2 mm; the range of the wire radius r used is 0.4 - 0.8 mm.

9. The laser wire welding method according to any one of claims 6 to 8, characterized in that: The base body of the workpiece to be welded or the base body after heat treatment has a tensile strength of not less than 1200 MPa, and there is an aluminum or aluminum-based coating on the surface of the base body. The workpiece to be welded is butt-welded. The mass percentage content of alloying elements in the wire at least satisfies the following relationships: 0.1% < C < 0.2% < Si < 1.2% < Mn < 3% < Ni, 2% < Cr + Mo < 4%, and 8% < Cr + Mo + Ni < 15%; in the butt welding without a welding gap, the values of the wire feeding speed V0, the welding speed V, and the average plate thickness D of the workpiece combination to be welded satisfy the relationship: V0 = (0.8 - 1.1) * (D - 0.8) * V.

10. The laser wire welding method according to claim 9, characterized in that: The mass percentage content of alloying elements in the wire also includes: 0.5% - 1.5% of Cu, 0.05% - 0.1% of Ti.

Images