JPH0829426B2 - Laser beam welding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding, for example, a laser beam to an overlapping portion composed of a flange portion and a lid of a container, and an overlapping portion composed of a cup-shaped lid fitted in the mouth portion of the container.

[0002]

2. Description of the Related Art Since a laser beam is capable of concentrating energy in a narrow region, it has recently been widely used for welding metal plates and the like. When a laser beam is applied to the welding of overlapping parts of metal plates, usually the laser beam is irradiated vertically to the overlapping part to melt one plate and then melt the material near the interface of the overlapping part. Weld. In this type of welding, the welding efficiency is poor because extra material that does not contribute to welding must be melted, and a laser beam generator with a considerably large laser output is required to increase the welding speed. There is a problem that a trace of melting remains on one plate to impair the appearance.

Recently, a fillet welding method has been proposed in which only the vicinity of a portion to be welded is melted by irradiation with a laser beam (Japanese Patent Laid-Open No. 57-112986). This method is applied to fillet welding of tin-free steel, but the overlapping portion is clamped by a cooling member and the fillet portion is irradiated with a laser beam to perform welding. In the case of this type of welding, the welding efficiency is higher than in the case of the above-mentioned conventional method because it does not melt the excess material, but the welding efficiency is still due to the loss due to the reflection of the laser beam from the material surface. Is hard to say enough.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a welding method using a laser beam for an overlapping portion, which enables high-speed welding with relatively high welding efficiency, that is, with a laser having a relatively small output. With the goal.

[0005]

According to the laser beam welding method of the overlapping portion of the present invention, the overlapping portion of the overlapping portion is overlapped so that the end surface of the first welding member and the end surface of the second welding member are aligned. A method of performing laser beam welding along the end face, along the vicinity of the end face of the surface to be the inner surface of the overlapping portion of at least one of the welding members, after forming a large number of grooves of minute depth, The overlapping part is formed, and the laser beam hits at least the end face part around the void while pressurizing the overlapping part with a pressing force such that the close contact part and the void part are alternately formed along the vicinity of the end face. The welding is performed by irradiating a laser beam along the direction in which the end face extends substantially at right angles to the plate thickness direction of the end face.

Further, the laser beam welding method of the superposed portion of the present invention is a superposition in which the end surface of the first welding member is superposed on the surface of the second welding member to form a step. A method of performing laser beam welding along the end face of a portion, wherein a large number of concave grooves having a minute depth are formed at least along the vicinity of the end face of the surface to be the inner surface of the overlapping portion of the first welding member. After that, the overlapping portion is formed, and the inner surface of the overlapping portion of the second welding member is pressed while pressing the overlapping portion with a pressing force such that the close contact portion and the void portion are alternately formed along the vicinity of the end face. A laser beam whose central axis has an angle of 10 to 60 degrees with respect to at least the end face portion around the void and the vicinity of the end face of the surface (hereinafter referred to as the surface vicinity portion).
It is characterized in that the irradiation is performed along the direction in which the end face extends so that the welding is performed.

[0007]

In the case of the first aspect of the invention, the laser beam impinges on the void portion and the end face portion around the void portion due to the concave groove having a minute depth. Since the height of the laser beam entering the void is very small, it is effectively reflected multiple times in the void,
That is, reflection is repeated between the walls of the void to efficiently melt the portion around the void. At the same time, the end face portion around the void and the end face portion near the contact portion are also melted. Therefore, the close contact portion is melted from three directions, and the solid phase portion which is not melted is also heated to a temperature close to the melting temperature by heat conduction. Therefore, the unmelted solid phase portion of the close contact portion is easily brought into pressure contact with each other by a light pressure such that the close contact portion is formed, and thus the overlapping portion is not crushed during welding. Therefore, the energy required for welding can be reduced as compared with the case of uniformly melting and welding along the end face of the overlapping portion. That is, laser beam welding can be performed with higher energy efficiency. Since the void has a small height, it is substantially filled with the molten material. Since the pressing force is within the above range, there is no possibility that the molten material will squeeze out or scatter due to the crushing during welding.

The operation in the case of the invention described in claim 2 is almost the same as that of the invention described in claim 1, but in this case, the end face of the first welding member is on the surface of the second welding member. Therefore, the irradiation direction of the laser beam is restricted, and the laser beam is irradiated so that the central axis has an angle of 10 to 60 degrees with respect to the inner surface of the overlapping portion of the second welding member.

If the angle of the central axis of the laser beam is smaller than 10 degrees, the amount of the molten material in the vicinity of the end face of the surface becomes small, and the unfilled portion is likely to be left in the void during high speed welding, which is not preferable. If the angle of the central axis exceeds 60 degrees, the amount of the laser beam that enters the void decreases, and the melting around the void slows down, making it difficult to perform high-speed welding, and in the vicinity of the end face of the surface. The melting depth in the plate thickness direction increases, which adversely affects the appearance and properties of that portion, which is not preferable.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, 1 is a first welding member made of a metal plate (for example, a low carbon steel plate), 2 is a second welding member made of the same metal plate, both of which are end faces 1a and 2
The overlapping portions 3 are formed so that a is aligned, that is, the same surface is formed. As shown in FIG. 2, along the vicinity of the end surface 1a of the inner surface 1b of the overlapping portion 3 of the first welding member 1, a large number of concave grooves 4 having a small depth h are formed close to each other. In the case of FIG. 1, the length, that is, the depth of the concave groove 4 is smaller than the width of the overlapping portion 3. Accordingly, along the vicinity of the end faces 1a, 2a, the cavity 5 formed by the concave groove 4 having a small height h and the close contact portion 6 having a small lateral width w are alternately formed.

Reference numeral 10 in FIG. 3 denotes an end surface 1 of the first welding member 1.
It shows an example of a device for forming the concave groove 4 on the surface of the vicinity of a, 11 is a lower guide tool, 12 is an upper holding tool, 13 is a feed finger, 14 is a support roll, 15 is a concave It is a knurling roll in which a ridge 15a corresponding to the groove 4 is formed. The first welding member 1 is transferred between the lower guide tool 11 and the upper press tool 12 by the feed finger 13, and along the vicinity of the end surface 1a of the surface to be the inner surface 1b of the overlapping portion 3, the knurling roll. The concave groove 4 is formed by 15.

In FIG. 1, 7 and 8 are pressing members, which are near the end face of the overlapping portion 3 with a pressing force that allows the contact portion 6 to be formed and does not crush the overlapping portion during welding. Pressurize the part.

Reference numeral 9 is a laser beam, and 9a is its central axis. The central axis 9a of the laser beam 9 is the end surface 1
Irradiation is performed so as to be a direction substantially perpendicular to the plate thickness directions of a and 2a, and the focal plane is near the end face and strikes at least the end face portion around the void portion 5. In this case, the laser beam 9 can be inclined from the direction perpendicular to the longitudinal direction of the end faces 1a, 2a, that is, the welding direction, and is usually within the range of 45 degrees in the welding direction or 45 degrees in the anti-welding direction from the orthogonal direction. Can tilt. The diameter D of the laser beam 9 at the laser irradiation portion varies depending on the type of laser used, but is usually about 0.1 to 0.5 mm. As a laser for the laser beam 9, a carbon dioxide gas laser, a YAG laser, or the like is preferably used.

The height h of the void 5 is equal to or longer than the wavelength of the laser so that the laser beam 9 can enter, and is a value that is appropriately filled with the molten metal generated around the void 5 as described later. It is less than or equal to 50% of the diameter D at the laser beam irradiation portion, and more preferably 30% or less.
% Or less. When using a carbon dioxide laser, the height h is 0.01 mm or more and 0.1 mm or less, more preferably 0.02 mm.
Therefore, it is desirable that the thickness is 0.07 mm or less. Further, it is desirable that the width d of the void portion 5 into which the laser beam 9 can easily enter be as large as possible, while the width w of the contact portion 6 be as small as possible. Usually, the width w of the contact portion 6 is preferably equal to or less than the diameter D of the laser beam 9, and more preferably the diameter D of the laser beam 9.
It is set to 50% or less. The width d of the void 5 is set to 30% or more, preferably 50% or more of the width w of the close contact portion 6. The optimum value is influenced by the type of metal plate, plate thickness, welding speed, laser wavelength, laser output, diameter on the irradiation surface of the laser beam, energy distribution of the laser beam, etc. Determined by experiment.

Welding in the vicinity of the end face of the overlapping portion 3 is performed as follows. When the overlapping portion 3 is moved in the direction of arrow A while being pressed by the pressing members 7 and 8 with an appropriate pressurizing force capable of being pressed and irradiated with the laser beam 9, the void portion 5 is formed.
The entering laser beam 9 undergoes multiple reflection in the void 5, that is, impinges on the side wall and the back wall of the void and is repeatedly reflected to melt the metal around the void 5. Since the void portion 5 has a small height, the molten metal near the end face of the void portion 5 is drawn into the inside by the surface tension and fills the void portion 5.

On the other hand, since the laser beam 9 is reflected on the upper and lower end faces of the contact portion 6, the output of the laser beam 9 is relatively small, and when the irradiation time is short because of the high speed movement, the depth at which the metal melts Is shallower than the void 5. However, the temperature rises to about 1000 ° C. or more due to the temperature rise due to the laser beam irradiation and the heat conduction from the molten metal around the void 5, so that the portion remaining in the solid phase of the contact portion 6 remains in the pressing members 7 and 8. The welded portion 16 is pressed by pressure.
Is formed. Since the pressing force is not so large as to crush the overlapping portion 3 during welding, there is no risk that the welded portion 16 will be crushed and the molten metal will squeeze out or scatter.

In FIG. 4, the end surface 1a of the first welding member 1 is on the surface 2b of the second welding member 2, and the end surface 1a is a step. Similar to the case of FIG. 1, a large number of concave grooves 4 having a small height h are formed along the inner surface 1b of the overlapping portion 3 of the first welding member 1 along the vicinity of the end surface 1a. There is. The length, that is, the depth of the groove 4 is smaller than the width of the overlapping portion 3. Therefore, along the vicinity of the end face 1a, the cavity 5 formed by the concave groove 4 having a minute height and the contact portion 6 having a small lateral width w are alternately and repeatedly formed. It is similar to the case of 1.

In the case of FIG. 4, the surface 2 of the second welding member 2
Since b extends to the laser beam 9 side, the irradiation direction of the laser beam 9 is different from that in the case of FIG. That is, the laser beam 9 has an angle θ between the inner surface 2c and the central axis 9a of the overlapping portion 3 of the second welding member 2 of 10 to 60 degrees, more preferably 15 to 45 degrees, and at least a gap. Part 5
Irradiation is performed so as to hit the peripheral end face 1a portion and the portion 2d of the surface 2b in the vicinity of the end face 1a, and to bring the focal plane almost at the end face 1a.

The diameter D of the laser beam in this case means, as shown in FIG. 4, the outermost portion 2d ₁ of the end face vicinity portion 2d of the surface, and the uppermost portion 1a ₁ of the end face 1a, which is hit by the laser beam 9. The diameter of an imaginary cylinder having a center line passing through (the outermost portion when hitting the outer surface 1c of the first welding member 1) and parallel to the central axis 9a. A laser beam 9 having a diameter D relatively larger than the plate thickness of the first welding member 1.
When the laser beam 9 is used,
Irradiation is performed over the end surface 1a and a part of the outer surface 1c. The same applies to the case of FIG.

Also in this case, the welded portion 16 can be formed by irradiating the laser beam 9 while moving the overlapping portion 3 in the direction of the arrow A in substantially the same manner as in FIG. However, in this case, since the laser beam 9 strikes the end face vicinity portion 2d of the surface of the second welding member 2 obliquely, multiple reflection in the void portion 5 is performed more actively than in the case of FIG. Further, since the laser beam 9 reflected from the end face vicinity portion 2d of the surface also strikes the end face 1a on the close contact portion 6, under other conditions, the welding efficiency is higher than that in the case of FIG. 1, that is, at a higher speed. Welding can be performed.

FIG. 5 is a plan view of the welded portion 16 formed as shown in FIG. 4, and FIGS. 6 and 7 are portions corresponding to the original void portion 5 and the close contact portion 6, respectively. FIG. In FIG. 5, 1a 'is the original end face 1a
And 5'is the original void 5 corresponding to the intersection of the surface and the surface 2b.
And 6'is a portion corresponding to the original contact portion 6. Reference numeral 17 indicated by diagonal lines is a melt-solidified portion, and reference numeral 18 in which a large number of points are formed is a pressure contact portion.

As shown in FIG. 8, the depth of the gap 5, that is, the depth, is larger than the width of the overlapping portion 3, and the void 5 may penetrate through the overlapping portion 3. Also in this case, the welded portion 16 can be formed efficiently by irradiating the laser beam 9 as in the case of FIG.

Specific data in the case of FIG. 4 are shown below.
Knurling the vicinity of the end surface of the tin-free steel blank having a plate thickness of 0.21 mm by the device 10 shown in FIG. 3 has a depth h of 0.04 mm, a width d of about 0.09 mm, and a long length. A large number of concave grooves 4 having an arcuate cross-section of about 0.3 mm were made so that the pitch was 0.2 mm. This blank 1 and the same blank 2 except that the knurling process was not performed were overlapped to form an overlapping portion 3 of the type shown in FIG. 4 having an overlapping width of 2 mm.

The superposing section 3 is pressurized by the pressing members 7 and 8 with a pressing force of about 2 kgf per 10 mm width in the welding direction, and the output is 1.2 kW while moving at a speed of 40 m / min.
Then, a carbon dioxide laser focused by a lens having a focal length of 95.3 mm was irradiated onto the overlapping portion 3 so that the irradiation angle θ was 25 degrees, and welding was performed to form a welded portion 16. The welded portion 16 was fusion-welded or pressure-welded over a depth of about 0.2 to 0.3 mm, and had a preferable weld strength.

For comparison, laser welding was performed in the same manner as described above except that the blank 1 similar to the blank 2 not subjected to knurling was used. In the obtained welded portion, only a molten bead having a depth of about 0.05 mm was formed in the vicinity of the end face of the blank 1, and it was not possible to obtain a preferable welding strength.

The concave groove 4 is also formed on the inner surface of the overlapping portion 3 of the second welding member 2, and the void portion 5 as shown in FIG. 9 and FIG. 10 is provided, and the laser welding is performed as described above. You may do it. Further, the concave groove 4 may be formed only in the second welding member 2.

FIG. 11 shows an application example in the case of the system of FIG. Reference numeral 20 denotes a metal can body having a flange portion 21 (made of, for example, a tin-plated steel plate), 22 denotes a metal lid (made of, for example, a tin-plated steel sheet), and the flange portion 21 and the peripheral edge portion 22a of the metal lid 22 are overlapped with each other. Thus, the circumferential overlapping portion 23 is formed. A concave groove is formed in advance on the inner surface near the end surface of the peripheral edge portion 22a, so that a large number of voids 5 exist in the circumferential direction near the end surface of the overlapping portion 23. By pressing the overlapping portion 23 with the flange receiver 24 and the pressing tool 25, and at the same time rotating the can body 20 and the lid 22 around the axis, the end face is irradiated with the laser beam 9 to form the welded portion 16. The can body 20 and the lid 22 can be joined together.

FIG. 12 shows an application example in the case of the system of FIG. Reference numeral 26 is a metal can body having a throttle opening 27, and 28 is a cup-shaped metal lid. The lid 27 is the mouth 27
A peripheral overlapping portion 29 is formed by being fitted in exactly. A large number of concave grooves are formed in advance on the inner surface near the end surface of the mouth portion 27, so that a large number of voids 5 exist in the circumferential direction near the end surface of the overlapping portion 29. The overlapping portion 29 is pressed by the core 30 and the pressing roll 31, and at the same time, the end face is irradiated with the laser beam 9 and the welding portion 16 is formed while rotating the can body 26 and the lid 28 around the axis. The can body 26 and the lid 28 can be joined together. Next, as shown in FIG. 13, a portion 28a of the peripheral wall portion of the lid 28 protruding from the mouth portion 27 is wound so as to cover the outer periphery of the mouth portion 27, so that the mouth end portion 32 that is safe and has an excellent appearance can be obtained. Can be formed.

FIG. 14 shows two pairs of rolls 36 while moving in the direction of arrow A a metal can body preform 35 having a stacking portion 34 having a void portion 5 and a contact portion 6 of the type shown in FIG. , 37, the laser beam 9 is radiated from the oblique direction (the angle with respect to the reference plane is θ) at an angle α to the direction perpendicular to the moving direction while pressing the welding part 16 in the middle of the pressing part of each roll. It shows a state of forming and manufacturing the metal can body 38.

Although the overlapping width of the overlapping portion 3 is extremely small (for example, 0.2 mm), the void portion 5 is inside the overlapping portion 3 and does not penetrate the overlapping portion 3. The pressure applied in this case is also such that the contact portion 6 is formed, and excessive pressurization that causes the molten metal to squeeze out or scatter is not performed. When manufacturing a can body, after the welded portion 16 is solidified,
It is desirable to apply pressure with a roll or the like to substantially eliminate the step portion.

The present invention is not limited to the above embodiments, and the welding member may be made of thermoplastic, for example. Further, the shape of the concave groove 4 may be any suitable shape, and for example, as shown in FIG. 15, it may be composed of concave groove portions 4a and 4b intersecting in a grid pattern. Further, as shown in FIG. 16, the groove 4 may be formed by knurling in a wave shape.

In FIG. 15, on the inner surface 1b of the overlapping portion 3 of the first welding member 1, inclined concave groove portions 4 intersecting each other are formed.
a and 4b are formed. These recessed groove portions 4a, 4b
Can be used as the void portion 5 of the overlapping portion 3. Such concave groove portions 4a and 4b are, for example, first processed by using a knurling roll having an oblique convex stripe, and then the concave groove 4b is formed by a knurling roll having a convex stripe inclined in the opposite direction. It is obtained by similarly processing in. In this case, there is an advantage that the lateral width of the void portion 5 of the overlapping portion 3 can be made relatively large and the lateral width of the contact portion 6 can be made relatively small.

In the case of FIG. 16, the portion near the end surface of the first welding member 1 is corrugated, and the groove 4 having a relatively wide width d is formed.
Can be used as the void portion 5 of the overlapping portion 3. Such a corrugated end face vicinity is obtained by, for example, processing by combining the knurling roll 15 and the supporting roll 14 made of an elastic body having a thin cylindrical surface in FIG.
That is, the concave groove 4c is formed by the knurling roll 15, the thin elastic body on the surface of the supporting roll on the opposite side is further deformed to form the protrusion 40, and the comparatively wide concave groove 4 is formed on the supporting roll side. It Also in this case, since the width of the contact portion 6 in the overlapping portion 3 can be narrowed and the width of the void portion 5 can be widened, welding with relatively high efficiency can be performed.

[0034]

According to the laser beam welding method of the overlapping portion of the present invention, high-speed welding is performed on the overlapping portion of the welding member with relatively high welding efficiency, that is, by irradiating a laser beam having a relatively small output. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a laser beam is applied to an overlapping portion which is a first aspect of the present invention.

FIG. 2 is a perspective view of the first welding member of FIG. 1 seen from the back side, showing the concave groove of the first example.

FIG. 3 is a partially cut front view showing an example of an apparatus for forming a groove of the first welding member shown in FIG.

FIG. 4 is a perspective view showing a state in which a laser beam is applied to the overlapping portion which is the second aspect of the present invention.

5 is a plan view of a weld formed by the method of FIG.

6 is a vertical cross-sectional view taken along the line VI-VI of FIG.

7 is a vertical cross-sectional view taken along the line VII-VII of FIG.

FIG. 8 is irradiating a laser beam on the overlapping portion which is the third aspect of the present invention. It is a perspective view showing a state.

FIG. 9 is a front view of an overlapping portion that is a fourth aspect of the present invention.

FIG. 10 is a front view of an overlapping portion that is a fifth aspect of the present invention.

FIG. 11 is a partially cut front view showing a first application example of the present invention.

FIG. 12 is a partially cut front view showing a second application example of the present invention.

13 is a longitudinal cross-sectional view of relevant parts showing a state after the welding portion in FIG. 12 is covered by being wound and wound.

[Explanation of symbols]

 1 1st welding member 1a End surface 1b Surface which becomes an inner surface 2 Second welding member 2a End surface 2b Surface 2d Surface end face vicinity part 3 Lapping part 4 Groove 5 Void part 6 Contact part 9 Laser beam 9a Center axis 23 Overlap Laying section 29 Lapping section 34 Lapping section

Claims (2)

[Claims] 1. A method of performing laser beam welding along an end face of a superposed portion, wherein the end faces of a first welding member and an end face of a second welding member are superposed so that they are aligned with each other, and at least one welding member is provided. After forming a large number of grooves with minute depth along the vicinity of the end face of the surface that should be the inner surface of the overlapping part, the overlapping part is formed, and close contact and voids alternate along the vicinity of the end surface. While pressurizing the overlapping portion with a pressurizing force that is formed in, the laser beam hits at least the end face portion around the void so that the laser beam strikes the end face substantially in the plate thickness direction along the direction in which the end face extends. A laser beam welding method for overlapping portions, which comprises irradiating a laser beam at a right angle to perform welding. 2. An end surface of the first welding member is superposed on the surface of the second welding member so as to form a step.
In the method of performing laser beam welding along the end face of the overlapping portion, a large number of concave grooves having a minute depth are formed at least along the vicinity of the end face of the surface to be the inner surface of the overlapping portion of the first welding member. After that, the overlapping portion is formed, and the inner surface of the overlapping portion of the second welding member is pressed while pressing the overlapping portion with a pressing force such that the close contact portion and the void portion are alternately formed along the vicinity of the end face. With respect to the central axis of the laser beam having an angle of 10 to 60 degrees, at least the end face portion around the void portion, and so as to hit the vicinity of the end face of the surface, irradiate along the extending direction of the end face for welding. A laser beam welding method for overlapping portions, which is characterized by carrying out.