JPH06170567A - Lap beam welding method - Google Patents

Abstract

PURPOSE:To reduce the deterioration of the joining strength and variation of the joining strength by irradiating the high density energy beam from the side of a member of thicker plate in welding the lapped members in a condition with a clearance. CONSTITUTION:Irradiation of the high density energy beam is executed from the side of a member of thicker plate in achieving the beam welding of the lapped plate members in a condition where there is a clearance between the contact surfaces. When the contact surfaces are plated, irradiation of the high density energy beam is executed from the side of the member having a thinner- plated contact surface or the member having the non-plated contact surface. This constitution allows the excellent welding of the respective members providing a stable welding strength without opening holes in the weld zone, and also allows the improvement of the productivity and maintenance of the parts precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superposition beam welding method for welding superposed members using a high-density energy beam.

[0002]

2. Description of the Related Art In the welding of relatively large members such as the assembly of automobile body panels,
After the appropriate parts are tack welded in advance, additional welding is performed. For this reason, in tack welding, although the joining strength between members is not required to be so high, an important characteristic is to minimize the amount of deformation of each member caused by welding.

Conventionally, laser welding as disclosed in, for example, Japanese Patent Laid-Open No. 60-49883 has been widely used as the tack welding and the additional welding.
In this laser welding, for example, when there is a clearance (hereinafter, referred to as a gap) between both contact surfaces of the superposed members, the members are clamped by a jig such as a roller and the welding parts are pressure-welded. By doing so, welding is performed.

[0004]

However, in the conventional laser welding described above, when there is almost no gap between the contact surfaces of the superposed members, the members are clamped and pressure-welded to each other. Although the amount of deformation of the member is small, if the gap becomes large, it is necessary to increase the pressure applied by the jig or press the number of jigs in order to press the welded part, and therefore, it is proportional to the size of the gap. Then, there is a problem that welding distortion, that is, the amount of deformation of each member increases, and the precision of the parts deteriorates.
In particular, when each of the above-mentioned members is a long object, when the surface roughness is rough, when the contact area is wide, or when the places where the members are clamped are limited, the gap between both contact surfaces is large. Therefore, the amount of deformation of each member is further increased, and the accuracy of parts is significantly reduced.

Therefore, for example, in tack welding, a non-contact welding method has been proposed in which welding is performed without pressing the welded portion. Since this non-contact welding method does not press-weld the welded portion, it is possible to reduce the amount of deformation of each member even if there is a gap between both contact surfaces, but on the other hand, the welded portion does not contact. For this reason, if the gap between both contact surfaces becomes large, welding defects will occur, which will cause new problems such as reduction in joint strength and variation in joint strength. Further, when the plate thickness of the member on the laser light irradiation side is thin and the gap is large, the metal at the welded portion may melt down and a hole may be opened in the member.

The superposed beam welding method of the present invention has been made in view of the above problems. Even when there is a gap between both contact surfaces of members, the joining strength of the welded portion is reduced and the joining is performed. It is an object of the present invention to provide a good welding method capable of maintaining the accuracy of parts by reducing the variation in strength and the amount of deformation of each member.

[0007]

In order to solve the above-mentioned problems, the superposed beam welding method according to the first aspect of the present invention comprises:
A superposition beam welding method for welding superposed members using a high-density energy beam with a clearance between the contact surfaces, and irradiating the high-density energy beam from the side of a member with a thick plate thickness. Is characterized by.

In order to solve the above-mentioned problems, the superposed beam welding method according to the second aspect of the present invention uses a high-density energy beam in a state where the superposed members have a clearance between both contact surfaces. A superposed beam welding method for welding is characterized in that when both the contact surfaces are plated, the high-density energy beam is irradiated from the side of the member having the contact surfaces with the thin plating thickness.

In order to solve the above-mentioned problems, the superposed beam welding method according to the third aspect of the present invention uses a high-density energy beam in a state where the superposed members have a clearance between both contact surfaces. A superposed beam welding method for welding, in which when one of the above contact surfaces is plated, a high-density energy beam is irradiated from the side of the member that has the contact surface that is not plated. Is characterized by.

[0010]

According to the method of claim 1, since the high-density energy beam is irradiated from the side of the member having a large plate thickness, the superposed members are welded with a clearance between both contact surfaces. Even if the clearance is large, it is possible to perform welding without forming a hole in the member on the side irradiated with the high-density energy beam.

Therefore, for example, even if each member is a long object, has a large surface roughness, has a large contact area, or has a limited number of parts to be clamped between the members, the welding parts are joined together. It is possible to reduce the strength, the variation in joining strength, and the amount of deformation of each member, and it is possible to perform good welding while maintaining the component accuracy.

According to the method of claim 2, when both contact surfaces are plated, high-density energy beams are irradiated from the side of the member having the contact surface with a small plating thickness to superimpose them. Since the members are welded together with a clearance between the contact surfaces, it is possible to suppress the evaporation amount of the plating material that is evaporated by the heat of the high-density energy beam.

Therefore, it is possible to suppress the steam generation amount of the plating material, which is a factor that hinders good welding, so that the joint strength at the welded portion is reduced, the joint strength is varied, and the deformation amount of each member is reduced. Can be reduced, and good welding can be performed while maintaining the precision of the parts.

According to the method of claim 3, when one of the contact surfaces is plated, the high-density energy beam is irradiated from the side of the member having the contact surface which is not plated. Due to this, the superposed members are welded together with a clearance between both contact surfaces,
It is possible to suppress the evaporation amount of the plated material that is evaporated by the high-density energy beam.

Therefore, it is possible to suppress the amount of vapor generated from the plating material, which is a factor that hinders good welding, so that the joint strength at the welded part is reduced, the joint strength varies, and the amount of deformation of each member. Can be reduced, and good welding can be performed while maintaining the precision of the parts.

[0016]

【Example】

[Embodiment 1] The following description will discuss Embodiment 1 of the present invention with reference to FIGS. 1 and 2. In this embodiment, as shown in FIG. 1, a flat plate-shaped first member 1
A flat plate-shaped second member 2 having a thickness smaller than that of the first member 1 is superposed, and both contact surfaces of the first and second members 1 and 2 are welded by a laser beam as a high-density energy beam. The superposition beam welding method is shown as an example.

A steel plate having a plate thickness of 1.2 mm was used as the first member 1 and a steel plate having a plate thickness of 0.7 mm was used as the second member 2. In addition, these first and second members 1 and
A CO ₂ laser welding machine is used as a laser welding machine for performing beam welding (hereinafter, referred to as laser welding) on ₂
Laser light was irradiated from the first member 1 side (direction A in FIG. 1). Welding conditions are welding output of CO ₂ laser welder 2.0
kw, welding time 0.4 sec, defocusing 0, spot welding, clearance between contact surfaces of the first and second members 1 and 2 (hereinafter referred to as gap) amount in the range of 0 mm to 1.0 mm I set it to.

For comparison, comparative laser welding was also performed in which laser light was emitted from the second member 2 side (B direction in the figure) under the same welding conditions as laser welding. Then, the welding strength (joint strength) of the welded portion subjected to the laser welding and the comparative laser welding was measured. The results of these measurements are shown in FIG.

As shown in FIG. 2, the welding strength (indicated by ● in the figure) when laser welding is performed from the first member 1 side to the superposed first and second members 1 and 2 is the gap. It can be seen that the amount is approximately constant at around 80 kgf over the range of 0 mm to 1.0 mm, has stable welding strength, and has a large gap allowable limit. As described above, the laser welding can satisfactorily weld the first and second members 1 and 2 even when the gap amount between both contact surfaces is 1.0 mm, for example.

On the other hand, the superposed first and second members 1
・ For the welding strength (indicated by ○ in the figure) when comparative laser welding was applied to 2 from the second member 2 side, the gap amount was 0 mm to
In the range of 0.3 mm, it is almost constant around 110 kgf and has stable welding strength, but when the gap amount becomes larger than 0.3 mm, the welding strength sharply decreases. As described above, the comparative laser welding cannot satisfactorily weld the first and second members 1 and 2 when the gap amount is large.

When comparative laser welding is performed from the second member 2 side in this way, the welding strength sharply decreases for the following reason. That is, the welding strength increases as the area of the molten metal portion in the welded portion increases. In the comparative laser welding, since the laser beam is irradiated from the side of the second member 2 having a thin plate thickness, when the gap amount is 0.3 mm or less, the area of the molten metal portion is widened by the heat of the laser beam, and the welding strength is large. On the other hand, when the gap amount is larger than 0.3 mm, the molten metal portion of the second member 2 is completely melted down and a hole is opened in the second member 2, and the first and second members 1, 2
This makes it difficult to weld.

From the above measurement results, in laser welding as superposed beam welding in which laser light is radiated from the side of the first member 1 having a large plate thickness, for example, the gap amount between both contact surfaces is 1.0 mm.
Even in such a case, it is understood that it is possible to satisfactorily weld the first and second members 1 and 2 with stable welding strength without forming a hole in the welding site. Therefore, for example, when the first and second members 1 and 2 are long objects, when the surface roughness is rough, and when the contact area is large, there are places where the first and second members 1 and 2 are clamped. Even when the number is limited or when the number of clamped portions is reduced, it is possible to reduce the welding strength of the welded portion and the variation of the welding strength, which improves the productivity and the first and second members 1 -It becomes possible to perform good welding while maintaining the part precision of 2.

In the first embodiment described above, the case where the first and second members 1 and 2 that have been overlapped are spot-welded has been described as an example, but of course, the first and second members 1 and 2 are used. Even in the case of continuous welding, laser welding can satisfactorily perform welding with stable welding strength. Further, the material of each member 1 and 2 is not limited to the above steel plate, and for example, each member 1 and 2 may be different materials. Further, the plate thickness of each member 1 and 2 is not limited to the thickness used in the first embodiment. In addition, the welding conditions are not limited to those in the first embodiment, and various changes can be made so that the welding conditions are optimal conditions according to the material and plate thickness of each member 1 and 2.

[Second Embodiment] The second embodiment of the present invention will be described below with reference to FIGS. 3 and 4. In this embodiment, as shown in FIG. 3, a flat plate-shaped first member 3 having a plating layer 5 formed on one surface and a flat plate-shaped second member 4 having a plating layer 6 formed on one surface are provided. As an example, a superposed beam welding method is shown in which the surfaces on which the plating layers 5 and 6 are formed are overlapped with each other to be contact surfaces, and the first and second members 3 and 4 are welded by laser light. .

The above-mentioned first and second members 3 and 4 have the same plate thickness, and a steel plate having a plate thickness of 0.7 mm is used. The first and second members 3 and 4 are plated so that the plating amount of the plating layer 5 is larger than the plating amount of the plating layer 5 (plating thickness). Was formed.
Further, the welding conditions of the laser welding are the same as those of the first embodiment, the laser beam is irradiated from the first member 3 side (C direction in FIG. 3), and both the first and second members 3 and 4 come into contact with each other. The gap between the surfaces was set to a size in the range of 0 mm to 0.4 mm.

For comparison, comparative laser welding was also performed in which laser light was emitted from the second member 4 side (D direction in the figure) under the same welding conditions as laser welding. Then, the welding strength of the welded portion subjected to the laser welding and the comparative laser welding was measured. The results of these measurements are shown in FIG.

As shown in FIG. 4, the welding strength (indicated by ● in the figure) when laser welding is performed from the first member 3 side to the superposed first and second members 3 and 4 is the gap. It can be seen that the amount is approximately constant at around 115 kgf over the range of 0 mm to 0.3 mm and has stable welding strength.

On the other hand, the superposed first and second members 3
・ For the welding strength (indicated by ○ in the figure) when comparative laser welding was applied to 4 from the second member 4 side, the gap amount was 0.1 mm.
In the range of up to 0.3 mm, the value is almost the same as that when laser welding is performed, and although the welding strength is stable, the welding strength drops sharply when the gap amount is 0 mm. As described above, in the comparative laser welding, it is difficult to satisfactorily weld the first and second members 3 and 4 when the gap amount is small.

When the comparative laser welding is performed from the second member 4 side in this way, the welding strength sharply decreases for the following reason. That is, in the comparative laser welding, since the laser beam is irradiated from the side of the plating layer 6 having a large plating amount, when the gap amount is 0 mm, the vapor of the plating material evaporated by the heat of the laser beam stays at the welding site. This is because the absorption of the laser beam by the second member 4 becomes unstable and blow holes are generated, which adversely affects the molten state of the metal at the welded portion of the second member 4.

From the above measurement results, laser welding as superposition beam welding in which laser light is irradiated from the side of the first member 3 on which the plating layer 5 having a small amount of plating is formed is the evaporation of the plating material evaporated by the laser light. Since the amount can be suppressed and the generation of blow holes is suppressed, the first and second members 3 and 4 can be welded well with stable welding strength even when the gap amount between both contact surfaces is 0 mm. You can see that it is possible. Therefore, since it is possible to suppress the amount of steam generated from the plated material, which is a factor that hinders good welding, it is possible to reduce the welding strength of the welded portion and reduce the dispersion of the welding strength, and to improve productivity. It is possible to improve the quality and perform good welding while maintaining the parts accuracy of the first and second members 3 and 4.

In the second embodiment described above, the case where the first and second members 3 and 4 that have been overlapped are spot-welded has been described as an example, but of course, the first and second members 3 and 4 are used. Even in the case of continuous welding, laser welding can satisfactorily perform welding with stable welding strength. Further, the material of each member 3 and 4 is not limited to the above steel plate, and for example, each member 3 and 4 may be different materials. Further, the plate thickness of each member 3 and 4 is not limited to the thickness used in the above-described second embodiment. Moreover, the welding conditions are not limited to those in the second embodiment, and various changes can be made so that the welding conditions are optimal conditions according to the material and plate thickness of each member 3 and 4.

[Third Embodiment] The third embodiment of the present invention will be described below with reference to FIGS. 5 to 9. In the present embodiment, as shown in FIG. 5, the first member 7 having a flat plate shape and the second member 8 having a substantially V-shape are overlapped with each other to form the first and second members 7 and 8. As an example, a superposed beam welding method of welding three points with laser light is shown.

As the above-mentioned first member 7, a mild steel plate (Stored Programming Control: SPC material) having a plate thickness of 1.2 mm is used, and as the second member 8, a plated layer (not shown) is applied on both sides. ) -Formed electroplated steel sheet with a thickness of 0.7 mm (Zn-Ni plating, plating amount: 30 g / m ^{2 on} both sides)
Was used. Further, the welding conditions of the laser welding were the same as in Example 1 except that the welding output of the CO ₂ laser welding machine was 2.4 kw and the welding time was 0.5 seconds, and the first member 7 side (E in FIG. 5). Direction) to irradiate a laser beam, and the gap amount between both contact surfaces of the first member 7 (hereinafter referred to as mild steel plate) and the second member 8 (hereinafter referred to as plated steel plate) is 0 mm to 1.0 mm.
The size was set in the range of mm.

For comparison, comparative laser welding was also performed in which laser light was irradiated from the plated steel plate 8 side (F direction in the figure) under the same welding conditions as laser welding. further,
For comparison with the above laser welding, spot welding was performed as a comparative example using the same mild steel plate 7 and plated steel plate 8. A portable single-phase AC welding machine was used as the spot welding machine for performing spot welding. The welding conditions were a welding current of 0.85 kA for a single-phase AC welding machine, an energization time of 13 cycles, and a pressure of 250 kg.

The amount of deformation of the mild steel plate 7 and the plated steel plate 8 due to welding is as shown in FIG. 6, with the mild steel plate 7 fixed and the rising portion 8a of the plated steel plate 8 before and after welding in the G direction. It was determined by measuring the displacement amount with the displacement meter 10. Further, the tensile load was measured in order to obtain the joint strength of the welded portion, and the standard deviation of the measured values of the tensile load was calculated. 7 to 9 show the measurement results of the welded portions to which the above three types of welding have been applied.
As for the amount of deformation, the deformation in the G direction has a + value, and the deformation in the opposite direction has a − value.

As shown in FIG. 7, the mild steel plates 7 are stacked together.
And the amount of deformation (indicated by ● in the figure) when the plated steel plate 8 is laser-welded is within ± 0.2 mm over the range of the gap amount of 0 mm to 1.0 mm.
It can be seen that in the range of 0.3 mm to 1.0 mm, it is approximately constant at 0.1 mm to 0.2 mm, and has good welding accuracy. As described above, laser welding can be performed without causing deformation of the mild steel plate 7 and the plated steel plate 8 even when the gap amount between both contact surfaces is 1.0 mm.

On the other hand, when the mild steel plate 7 and the plated steel plate 8 are spot-welded, the deformation amount (indicated by Δ in the figure) is
It can be seen that the welding accuracy increases as the gap amount increases, and especially when the gap amount exceeds 0.3 mm, it becomes 0.4 mm or more. Thus, in spot welding, if the gap amount exceeds 0.3 mm, it becomes impossible to perform welding without causing deformation of the mild steel plate 7 and the plated steel plate 8.

Further, as shown in FIG. 8, the tensile load (indicated by ● in the figure) when laser welding the mild steel plate 7 and the plated steel plate 8 is 150 kgf over the range of the gap amount of 0 mm to 1.0 mm. It is almost constant before and after, indicating that the welded part has stable joint strength. Further, as shown in FIG. 9, the standard deviation σ of the measured values of the tensile load (indicated by ● in the figure) is substantially constant at 10 or less, and the above-mentioned bonding strength can be obtained with good reproducibility. I understand. As described above, laser welding is performed on the mild steel plate 7 and the plated steel plate 8.
Can be welded with good reproducibility and stable joint strength.

On the other hand, as shown in FIG. 8, the tensile load (indicated by Δ in the figure) when spot welding is performed on the mild steel plate 7 and the plated steel plate 8 decreases as the gap amount increases, It can be seen that the joint strength of the welded part depends on the size of the gap amount. In addition, the tensile load (indicated by ○ in the figure) when comparative laser welding is applied to the mild steel plate 7 and the plated steel plate 8 has a gap amount of 0 mm to 1.0 mm.
Although it is about 200 kgf over the range of, and is slightly larger than the tensile load when the above laser welding is performed, as shown in FIG. 9, the standard deviation σ of the measured values of the tensile load (in the figure, (Indicated by ○) is 15 or more,
It can be seen that there are variations in the bonding strength of the welded parts. That is, the comparative laser welding makes it impossible to weld the mild steel plate 7 and the plated steel plate 8 with good reproducibility and stable joining strength.

The reason why the measured value of the tensile load varies when the comparative laser welding is performed from the side of the plated steel plate 8 is as follows. That is, in the comparative laser welding, since the laser beam is irradiated from the plated steel plate 8 side, the plating layers formed on both surfaces of the plated steel plate 8 are evaporated by the heat of the laser light. Therefore, the vaporized vapor of the plating material stays in the welded portion, the absorption of the laser beam by the plated steel sheet 8 becomes unstable, and the welded state of the metal in the welded portion of the plated steel sheet 8 varies, and this welded state varies. Will cause variations in the bonding strength of the welded part. Further, since the plated steel plate 8 is thinner than the mild steel plate 7, the allowable limit of the gap amount is about 0.8 mm, and when the gap amount becomes 1.0 mm, the laser beam is irradiated on the plated steel plate 8. The part completely melts and a hole is formed in the plated steel plate 8, making it impossible to perform welding.

From the above measurement results, laser welding as superposed beam welding in which laser light is radiated from the side of the mild steel plate 7 where the plate thickness is thick and the plating layer is not formed, is the evaporation amount of the plating material evaporated by the laser light Therefore, even when the gap amount between both contact surfaces is 1.0 mm, it is possible to weld the mild steel plate 7 and the plated steel plate 8 with stable reproducible joint strength and without causing deformation. You can see that it is possible. Therefore, since it is possible to suppress the amount of steam generated from the plated material, which is a factor that hinders good welding, it is possible to reduce the welding strength of the welded portion and reduce the dispersion of the welding strength, and to improve productivity. As a result, it is possible to improve the quality of the mild steel plate 7 and the plated steel plate 8 while maintaining good part precision. In addition, for example, when the first and second members 1 and 2 are long ones, when the surface roughness is rough, and when the contact area is large, there are places where the first and second members 1 and 2 are clamped. Even if there is a limit or if the number of clamped parts is reduced, it is possible to perform good welding while maintaining the component accuracy of the mild steel plate 7 and the plated steel plate 8.

In the third embodiment, the case where the superposed mild steel plate 7 and plated steel plate 8 are welded at three points has been described as an example, but of course, the mild steel plate 7 and plated steel plate 8 are continuously welded. Even in the case of performing laser welding, it is possible to perform welding with reproducible and stable joint strength without causing deformation. Further, the materials of the first and second members 7 and 8 are not limited to the above-described mild steel plate and plated steel plate, and for example, the members 7 and 8 may be the same material. Further, the plate thickness of each member 7 and 8 is not limited to the thickness used in the above-mentioned third embodiment. In addition, the welding conditions are not limited to those in the third embodiment, but can be variously changed so as to be the optimum conditions according to the material and plate thickness of the members 7 and 8.

[0043]

As described above, the superposed beam welding method according to the first aspect of the present invention is a method of irradiating a high-density energy beam from the side of a member having a large plate thickness.

Therefore, for example, even if each member is a long product, has a large surface roughness, has a large contact area, or has a limited number of parts to be clamped between the members, the welding parts are joined together. It is possible to reduce the strength, reduce the variation in the bonding strength, and reduce the amount of deformation of each member, and it is possible to perform good welding while maintaining the component accuracy.

In the superposed beam welding method according to the second aspect of the present invention, as described above, when both contact surfaces are plated, the high-density energy is applied from the side of the member having the contact surface with the thin plating thickness. This is a method of irradiating a beam.

Therefore, it is possible to suppress the steam generation amount of the plating material, which is a factor that hinders good welding, so that the joint strength at the welded portion is reduced, the joint strength is varied, and the deformation amount of each member is reduced. It is possible to reduce the welding cost, and it is possible to perform good welding while maintaining the component accuracy.

In the superposed beam welding method according to the third aspect of the present invention, as described above, when any one of the contact surfaces is plated, the member has a contact surface which is not plated. This is a method of irradiating a high-density energy beam from the side.

Therefore, it is possible to suppress the amount of vapor generated from the plating material, which is a factor that hinders good welding, so that the joint strength at the welded part is reduced, the joint strength varies, and the deformation amount of each member. It is possible to reduce the welding cost, and it is possible to perform good welding while maintaining the component accuracy.

[Brief description of drawings]

FIG. 1 is a front view of essential parts of first and second members to which laser welding as superposed beam welding according to a first embodiment of the present invention is applied.

2 of the welding applied to the first and second members of FIG.
It is a graph which shows the relationship between a gap amount and welding strength.

FIG. 3 is a front view of essential parts of first and second members to which laser welding as superposed beam welding according to a second embodiment of the present invention is applied.

FIG. 4 is a representation of the welding performed on the first and second members of FIG.
It is a graph which shows the relationship between a gap amount and welding strength.

FIG. 5 is a perspective view of first and second members to which laser welding as superposed beam welding according to a third embodiment of the present invention is applied.

FIG. 6 is an explanatory diagram showing a method of measuring the deformation amount of the first and second members of FIG.

7 is a view of the welding applied to the first and second members of FIG.
It is a graph which shows the relationship between the amount of gaps, and the amount of deformation.

FIG. 8 of the welding applied to the first and second members of FIG.
It is a graph which shows the relationship between a gap amount and a tensile load.

9 is a graph showing the relationship between the gap amount and the standard deviation of the tensile load of FIG.

[Explanation of symbols]

 1 1st member 2 2nd member 3 1st member 4 2nd member 5 plating layer 6 plating layer 7 mild steel plate (1st member) 8 plating steel plate (2nd member)

Claims (3)

[Claims] 1. A superposition beam welding method for welding superposed members using a high-density energy beam in a state where there is a clearance between both contact surfaces, wherein high-density energy is applied from the side of a member having a thick plate thickness. A superposed beam welding method characterized by irradiating a beam. 2. A superposition beam welding method for welding superposed members to each other with a clearance between both contact surfaces by using a high-density energy beam, wherein both contact surfaces are plated. In this case, the superposed beam welding method is characterized in that the high-density energy beam is irradiated from the side of a member having a contact surface with a thin plating thickness. 3. A superposition beam welding method for welding superposed members to each other with a clearance between both contact surfaces using a high-density energy beam, wherein plating is performed on one of the contact surfaces. A high-density energy beam is radiated from the side of a member having a non-plated contact surface when the superposed beam welding method is used.