JPH05154678A - Laser beam welding method for sheet metals - Google Patents

Abstract

PURPOSE:To obtain the laser beam welding method of the sheet metals capable of economically and efficiently welding and joining the sheet metals from the outside thereof. CONSTITUTION:An end of one sheet metal 9 is bent inside and formed in a stepped shape by the thickness of the other sheet metal 10 to form a joining flange 9a and a joining flange 10a of an upper end of the sheet metal 10 is superposed on the outside of the joining flange 9a. A welding head 4 supplied with a laser beam via an optical fiber 5 from a laser beam generator 1 is arranged on the outside of the sheet metals 9 and 10, the welding head 4 is fitted on the hand 3 of a robot and both joining flanges 9a and 10a are subjected to laser beam welding while the sheet metal 10 is pressurized inwards by an idle rolling roller. It is desirable to perform welding and joining while attracting the sheet metal 9 outwards by an attracting mechanism provided separately, further, joining is performed between a free end of the joining flange 10a and a stepped part of the joining flange 9a and further, joining is sometimes performed in zigzags.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method for thin plates, and more particularly to a method for welding thin plates of a three-dimensional thin plate structure by laser light.

[0002]

2. Description of the Related Art Conventionally, spot welding has been widely used as a technique for welding and joining the ends of thin plates in a three-dimensional thin plate structure such as automobiles and home electric appliances. Weld one thin plate using Joule heat as a heat source by energizing one electrode while striking one electrode while the other end is sandwiched between the two electrodes. It is a technology to do.

In the welding technique by the spot welding, since the spot welding is performed at predetermined intervals, the joint strength and rigidity are poor, and the spot diameter is large, so the width of the joint flange portion is large, and the head of the spot welder is considerably large. Since it is large and heavy, it is difficult to weld in narrow spaces, and a large robot is required as a robot for attaching a spot welder, which are various drawbacks. By the way, recently, a laser welding technique for welding using a laser beam as a heat source has been put into practical use. The welding head is provided with a pair of rollers for forming the joint flange portions and for sandwiching the joint flange portions. While sandwiching both joint flange portions with the pair of rollers, a thin plate is provided at the abutting portion of both joint flange portions. A technique is disclosed in which laser light is emitted from orthogonal directions and butt welding is performed.

However, in order to weld a thin plate of a three-dimensional thin plate structure or the like, a laser light output of 1 kw or more is required. As such a high output laser, a CO ₂ laser, a YAG laser, the present application is applied. Iodine lasers and the like that have been put to practical use by humans are known. However, since the laser light of the CO ₂ laser cannot be guided by the optical fiber, there are various restrictions in use. The YAG laser is capable of guiding the fiber, but has a difficulty in using a small-diameter optical fiber. Although it is difficult to apply to welding thin plates of the body, the iodine laser is suitable for welding thin plates of a three-dimensional thin plate structure because it can guide light with a small diameter optical fiber and increase output.

[0005]

In the spot welding technique, since welding is performed with two thin plates sandwiched between a pair of electrodes, the ends of the two thin plates are overlapped and welded to the outside thereof. Even if it is not impossible to place the head and perform welding, in that case, the back electrode corresponding to multiple welding points must be placed in advance, which makes the welding device large, complicated, and economical. Moreover, there is a problem that welding cannot be performed efficiently. In the laser welding technique described in the above publication, since it is necessary to form a V-shaped joint flange at the ends of two thin plates, it is possible to weld thin plates of a three-dimensional thin plate structure that requires a planar outer surface. It is impossible to apply. It is an object of the present invention to provide a laser welding method for thin plates that enables economical and efficient welding and joining of the thin plates from the outside.

[0006]

According to a first aspect of the present invention, there is provided a laser welding method for a thin plate according to claim 1, wherein the ends of the two thin plates are welded together by a laser beam projected in a plate thickness direction.
One of the ends of the two thin plates is bent and formed inward by a step thickness by the thickness of the other end, and the other end is superposed on the outside of the one end, and the other end is formed. While projecting laser light from the outside of the part, the laser light is moved along both ends, and one end and the other end are welded continuously or intermittently. It is a thing.

According to a second aspect of the present invention, there is provided a laser welding method for a thin plate according to the first aspect, wherein when one end portion is bent and formed, a predetermined width portion on the free end side of the one end portion is substantially inwardly formed. It is characterized in that the reinforcing flange is formed by bending at a right angle.

A thin plate laser welding method according to a third aspect of the present invention is characterized in that, in the method of the first aspect, the other end portion is welded while being pressed inward.

A thin plate laser welding method according to a fourth aspect of the present invention is characterized in that, in the method according to the third aspect, the one end portion is welded while being pulled outward.

A thin plate laser welding method according to a fifth aspect is the method according to the third aspect, wherein the laser beam is moved in the width direction of the other end when the laser beam is moved along both the ends. Is also characterized by reciprocating movement with a predetermined amplitude.

A thin plate laser welding method according to a sixth aspect is the method according to the third aspect, wherein the laser beam is projected between a free end of the other end and a step portion of one end opposite to the free end. It is characterized by being welded and joined.

[0012]

In the laser welding method for thin plates according to the first aspect, one of the ends of the two thin plates is bent inward by a step thickness by the plate thickness of the other end, and one end of the two ends is bent. Since the other end is overlaid on the outside and both ends are welded and joined, the outer surfaces of the two thin plates can be made the same surface to enhance the appearance, and the free end of the other end can be used as one end. By abutting on the stepped portion, the other end can be easily and accurately positioned with respect to the one end. Further, since welding is performed by projecting a laser beam from the outside of the other end in the plate thickness direction, welding can be performed without disposing any welding equipment inside the two thin plates. It is possible to efficiently weld from the outside of the thin plate without being restricted by the shape and structure.

According to the thin plate laser welding method of the second aspect, basically the same operation as that of the first aspect can be obtained.
When one end is bent and formed, a predetermined width portion on the free end side of the one end is bent and formed inward at a substantially right angle to form a reinforcing flange. The shape of the part can be retained, and the adhesion between both ends can be improved.

According to the thin plate laser welding method of the third aspect, basically the same operation as that of the first aspect can be obtained.
Since the other end portion is welded and joined while being pressed inward, it is possible to join the both end portions in a state in which they are in close contact with each other.

According to the thin plate laser welding method of the fourth aspect, the same effect as that of the third aspect can be basically obtained.
Since one end portion is welded and joined while being pulled outward, it is possible to join the both end portions in a state where the adhesion is secured, and welding quality can be secured.

According to the thin plate laser welding method of the fifth aspect, basically the same effect as that of the third aspect can be obtained.
When the laser light is moved along both ends, the laser light is also reciprocally moved with a predetermined amplitude in the width direction of the other end, so that both ends can be joined in a zigzag shape and the welding strength is improved. Can be raised.

According to the thin plate laser welding method of the sixth aspect, basically the same effect as that of the third aspect can be obtained.
Since laser light is projected and welded between the free end of the other end and the step of the one end opposite thereto, the welding strength is increased and the free end of the other end is opposed to this. The appearance can be enhanced by filling a weld bead between the steps of one end.

[0018]

As described in the above section, the present invention provides the following effects. According to the laser welding method for thin plates according to claim 1, the outer surfaces of the two thin plates can be made to be the same surface to enhance the appearance, and the free end of the other end contacts the step part of one end. It is possible to easily and accurately position the other end with respect to one end by contacting, and to efficiently weld from the outer side of the thin plate without being restricted by the shape or structure of the thin plate structure.
And the like.

According to the thin plate laser welding method of the second aspect, basically the same effect as that of the first aspect can be obtained, and the shape of one end can be maintained by the reinforcing action of the reinforcing flange. It is possible to improve the adhesiveness of the ends.

According to the thin plate laser welding method of the third aspect, basically the same effect as that of the first aspect can be obtained. By welding the other end while pressing the other end inward, the two ends can be joined in a state of being substantially in close contact with each other, and the welding quality can be improved.

According to the thin plate laser welding method of the fourth aspect, basically the same effect as that of the third aspect can be obtained.
By welding the one end while pulling it outward, it is possible to perform the welding while ensuring the adhesion of both ends, and it is possible to secure the welding quality.

According to the thin plate laser welding method of the fifth aspect, basically the same effect as that of the third aspect can be obtained. By reciprocating the laser beam in the width direction of the other end portion at a predetermined amplitude during welding and joining, both ends can be joined in a zigzag shape, and welding strength can be significantly increased.

According to the thin plate laser welding method of the sixth aspect, basically the same effect as that of the third aspect can be obtained. Weld strength is improved by projecting laser light between the free end of the other end and the step of the one end opposite to it, thereby increasing the welding strength and facing the free end of the other end. It is possible to enhance the appearance by filling the gap between the steps at one end with welding beads.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment-See Figs. 1 and 2. First, a laser welding device will be described. The laser welding device includes a laser beam generator 1 and a hand 3 at the tip of an arm 2 of an articulating robot for welding. The welding head 4 mounted on the welding head 4 and the roller unit 6 fixed to the welding head 4 are provided.
This is an iodine laser generator that supplies iodine gas into excited active oxygen to generate laser light having a wavelength of about 1.3 μm. The laser light generated by this laser light generator 1 is applied to the welding head 4 by the optical fiber 5. It is configured to guide the fiber. The welding head 4 is
The optical fiber 5 has a convex lens 7 that converts the divergent light of the laser light emitted from the partially convex spherical tip into a convergent light. The convergent light is projected from the welding head 4 to the outside, and a predetermined distance is obtained from the tip of the welding head 4. Since the light beams are converged at the positions separated by a distance, the ends 9a, 10a of the two thin steel plates 9, 10 can be welded and joined to each other at the tip of the converged laser beam 8 as shown in the figure. The welding head 4 may be provided with a gas introduction chamber and a ring-shaped gas ejection hole for gas-shielding the emitted laser beam 8 with argon gas.

The welding head 4 is fixed to the welding head 4 by internally fitting and fixing the welding head 4 to the annular portion 12 of the frame 11 of the roller unit 6, and the welding head 4 is attached to the lower arm 13 of the frame 11 by the thin plate 9. The thin plate 10 in a state of being held at a predetermined distance position suitable for welding with respect to 10
Idler roller 1 that rolls by pressingly contacting the outer surface 10b of the roller
4 is provided via a vertically oriented shaft. The laser light generator 1 is not limited to the one described above, and a YAG laser laser light generator may be used.
The idler roller 14 may be formed in a drum shape in which the ground contact surface contacting the thin plate 10 is in the form of a medium-high drum, or an idler ball may be provided instead of the idler roller 14.

A method for welding and joining the ends 9a, 10a of the two thin plates 9, 10 using the laser welding apparatus will be described. The illustrated thin plates 9 and 10 have a plate thickness of 0.8 to 0.8 that constitutes a part of a three-dimensional thin plate structure for automobiles and home appliances.
Two thin steel plates of about 1.2 mm are shown, and in the processing stage of the thin plates 9 and 10, the lower end of the upper thin plate 9 is bent inward in a stepwise manner by the plate thickness of the lower thin plate 10. The joining flange 9a having a predetermined width is formed, and the joining flange 10a is formed at the upper end of the lower thin plate 10 so as to be assembled in contact with the outer surface of the joining flange 9a. Next, a pair of upper and lower vertical thin plates 9 and 10 are placed in a predetermined positional relationship, the joining flange 10a is overlapped and brought into contact with the outer surface of the joining flange 9a, and both thin plates 9 are attached by an assembling jig (not shown). 10,
Hold fixed.

Next, the welding head 4 is attached to both joint flanges 9.
a, 10a are set to one end side in the length direction, the idler roller 14 is brought into contact with the outer surface of the thin plate 10 to press the thin plate 10 inward, and the welding head 4 is held in a horizontal posture. While the laser light is being supplied from the light generator 1, the robot welds the welding head 4 to the both joint flanges 9
The joint flanges 9a and 10a are weld-joined at a high speed by moving the joint flanges 9a and 10a along the lengths a and 10a at a predetermined speed. Therefore, the two joining flanges 9a and 10a are integrally joined by the welding bead 15 having a width of about 1 to 3 mm as shown in FIG. By moving the welding head 4 along the joint flanges 9a and 10a and reciprocally moving the weld head 4 in the vertical direction at a predetermined amplitude within the width range of the joint flanges, as shown in FIG. Zigzag weld beads 16 may be formed as shown in phantom. With this zigzag weld bead 16,
The bonding strength can be remarkably increased. In the following embodiments, the same components as those of the present embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only different configurations will be supplementarily described.

Second Embodiment: See FIG. 3 When the joint flange 9a is formed by bending, the approximately 1/3 width portion of the joint flange 9a on the free end side (lower end side) is bent inward at a substantially right angle. The reinforcing flange 9b is formed by molding. When the reinforcing flange 9b is formed in this way, the shape of the joining flange 9a is easily maintained in a regular shape due to the reinforcing action, and the joining flange 9a and the joining flange 10a can be welded and joined to each other in a close contact state.

Third Embodiment: See FIG. 4 When the joint flange 9A is formed by bending, the reinforcing flange 9b is formed as in the second embodiment, and the step of the step portion 9c of the joint flange 9A is enlarged. In addition, an outwardly facing groove 9d is formed between the stepped portion 9c and the base end of the reinforcing flange 9b, so that the outer surface of the base end of the reinforcing flange 9b and the inner surface of the joining flange 10a are securely brought into close contact with each other. The outer surface of the base end of the reinforced flange 9b and the joint flange 10
Weld and join a.

Fourth Embodiment ... See FIG. 6 An upper arm 17 is provided on the annular portion 12 of the frame 11 of the roller unit 6A, and the following negative pressure suction mechanism 20 is provided on the upper arm 17. A negative pressure cylinder 21 is attached to the upper arm 17.
The suction pad 23 for sucking the upper thin plate 9 is attached to the tip of the rod 22 of the negative pressure cylinder 21, and the inside of the suction pad 23 is communicated with the negative pressure chamber 25 of the negative pressure cylinder 21 through the communication hole 24. The piston 26 is biased toward the rod 22 by a spring 27, and the negative pressure chamber 27 is connected with a hose 28 for introducing a negative pressure from an external negative pressure source. Using the welding head 4 and the roller unit 6A, the joining flange 9
In the case of intermittent welding by spot welding along a and 10a, the suction pad 23 in a state in which a negative pressure is not introduced is brought into contact with the thin plate 9 at each point to be welded, and then the negative pressure chamber 25 Negative pressure is introduced to the suction plate 23, and the thin plate 9 is sucked by the suction pad 23, and the suction pad 23 is welded and joined by the negative pressure cylinder 21 to the outside, and then the negative pressure is released to suck the suction pad 23. The suction pad 23 is moved toward the thin plate 9 by the elastic force of the spring 27 while being opened, and then the welding head 4 is moved to the next welding point, which is repeated in the same manner as described above. However, the negative pressure cylinder 21 and the suction pad 23 are not integrally provided on the welding head 4, but a plurality of negative pressure cylinders 21 and the suction pad 23 are mounted on an assembly jig or the like. When the thin plates 9 are sucked and attracted to be weld-joined, they can be continuously weld-joined.

Fifth Embodiment--See FIG. 5 An annular portion 12A of the frame 11 of the roller unit 6B.
Is inclined downward about 45 degrees with respect to the horizontal plane, and the welding head 4 is fixed to the annular portion 12A in the same inclination. The welding head 4 projects laser light obliquely from above and joins The welding is continuously performed along the boundary line between the free end 10b of the flange 10a and the step 9c of the joining flange 9a. By doing so, the cross-sectional area of the deposited metal is increased, the joint strength is improved, and the gap between the boundary lines is filled with the deposited metal, so that the appearance is improved.

Sixth Embodiment--See FIG. 7 The upper arm 30 of the frame 11 of the roller unit 6C has
The idler roller 31 made of a permanent magnet that rolls while sucking the outer surface of the thin plate 9 in a state where the welding head 4 is held at a predetermined distance position suitable for welding with respect to the thin plates 9 and 10 is provided with a vertical axis. Is provided. The idler roller 31 made of a permanent magnet is for attracting the upper thin plate 9 to a predetermined position with respect to the welding head 4. The method of welding and joining using the welding head 4 and the roller unit 6C is basically the same as that of the first embodiment, but the idle roller 14 is used.
The difference lies in that the thin plate 10 is pressed by and the thin plate 9 is welded while being sucked by the idler roller 31 made of a permanent magnet. Since the thin plate 10 is welded while pressing the thin plate 9 and sucking the thin plate 9 in this manner, the welding quality can be improved by welding and joining with the joint flange 9a and the joint flange 10a in close contact with each other.

Seventh Embodiment--See FIG. 8 The upper arm 30 of the frame 11 of the roller unit 6D includes:
An attraction magnet 32, which is a permanent magnet or an electromagnet, is provided so that the welding head 4 is located at a predetermined small distance from the outer surface of the thin plate 9 while the welding head 4 is held at a predetermined distance suitable for welding with respect to the thin plates 9 and 10. It is attached. At the time of welding and joining, the welding and welding are basically performed in the same manner as in the first embodiment, but the idler roller 14 presses the thin plate 10 and the attraction magnet 32 attracts the thin plate 9 to perform welding. Thus, as in the sixth embodiment, the joint flange 9a and the joint flange 10a are joined together.
It is possible to improve the welding quality by welding and joining in a state where they are in close contact with each other.

Eighth Embodiment ... See FIG. 9. A rod 34 is slidably inserted into a cylindrical member 33 forming the upper arm of the frame 11 of the roller unit 6E, and the rod 3
An attracting magnet 35 made of an electromagnet is fixed to the tip of 4,
The inner end of the coil spring 36 fitted onto the tubular member 33 is fixed to the attracting magnet 35, and the outer end of the coil spring 36 is attached to the tubular member 3.
3, the coil spring 36 extends a little in the illustrated state to attract the attracting magnet 35 outward. At the time of welding and joining, basically, welding and joining are carried out in the same manner as in the first embodiment, but the idler roller 14 presses the thin plate 10 and the attracting magnet 35 attracts the thin plate 9 for welding. Similar to the seventh embodiment, the welding quality can be improved.

Ninth embodiment: see FIG. 10. The upper arm 40 of the frame 11 of the roller unit 6F is
A double-acting air cylinder 41 is rotatably supported by a pair of shafts 42, a hook 44 is formed at the tip of a rod 43 of the cylinder 41, and a small hole 45 is spot welded to the thin plate 9. It is formed above the welding point, a pair of cams 46 and 47 is fixed to the rod 43, and a pair of cam guides 48 and 49 is provided on the upper arm 40. The illustrated state is maintained by the engagement of the cam 46 and the cam guide 48, and when the welding head 4 and the roller unit 6F are brought closer to the position of the welding point in this state, the hook 44 is inserted into the small hole 45, Then rod 4
When 3 is retracted, the engagement between the cam 47 and the cam guide 49 causes the hook 44 to engage with the thin plate 9 by the engagement with the cam guide 49 so that the thin plate 9 is pulled outward. Spot welding shall be performed.

Tenth Embodiment ... See FIG. 11. A drill unit 50 is fixedly provided on the welding head 4, and the welding head 4 is made to correspond to the position of the welding point to be spot-welded. The welding head 4 performs welding by using the welding head 4 in a state where the drill 53 is driven through the gear box 52 to pierce the joint flanges 9a and 10a and the joint flanges 9a and 10a are in close contact with each other. Although the roller unit is fixedly provided on the welding head in the above-mentioned embodiments, the roller unit may be independently provided on another welding jig or the like with respect to the welding head. Further, the welding head and the roller unit are not limited to those of the embodiment, and various modifications and auxiliary members may be added without departing from the technical idea disclosed in the embodiment. I can.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a laser welding device.

FIG. 2 is a partial front view seen from the outer surface of the thin plate after welding and joining.

FIG. 3 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

FIG. 4 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

FIG. 5 is a side view of a joining flange, a welding head and a roller unit according to another embodiment.

FIG. 6 is a side view of a joining flange, a welding head and a roller unit according to another embodiment.

FIG. 7 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

FIG. 8 is a side view of a joining flange, a welding head and a roller unit according to another embodiment.

FIG. 9 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

FIG. 10 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

FIG. 11 is a side view of a joining flange, a welding head, and a roller unit according to another embodiment.

[Explanation of symbols]

1 Laser Light Generator 4 Welding Head 5 Optical Fiber 6, 6A, 6B, 6C, 6D, 6E Roller Unit 9 Thin Plate 9a Joint Flange 9b Reinforcing Flange 9c Step 10 Thin Plate 10a Joint Flange 14 Roller 20 Negative Pressure Suction Mechanism 31 Permanent Magnet Made Idler roller 32 Suction magnet 35 Suction magnet 36 Coil spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihiro Nomaguchi 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kawasaki Heavy Industries, Ltd. Tokyo Head Office

Claims (6)

[Claims] 1. A method of welding and joining the ends of two thin plates with each other by a laser beam projecting in the plate thickness direction, wherein one of the ends of the two thin plates is inside by the thickness of the other end. Bending in a stepped shape, superimposing the other end on the outside of the one end, while projecting laser light from the outside of the other end, laser light along both ends. A laser welding method for a thin plate, which comprises moving and joining one end and the other end continuously or intermittently by welding. 2. A reinforcing flange is formed by bending a predetermined width portion on the free end side of one end inwardly at a substantially right angle when the one end is bent. The method for laser welding a thin plate according to claim 1. 3. The laser welding method for a thin plate according to claim 1, wherein the other end is welded and joined while being pressed inward. 4. The laser welding method for a thin plate according to claim 3, wherein the one end portion is welded and joined while being pulled outward. 5. When the laser light is moved along both ends, the laser light is also reciprocated with a predetermined amplitude in the width direction of the other end.
A method for laser welding a thin plate according to. 6. The thin plate laser according to claim 3, wherein the laser light is projected and welded between the free end of the other end and the step of the one end facing the free end. Welding method.