JPS6261786A - Laser butt welding method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for forming a laser butt weld, and more specifically, a method for forming a laser butt weld, and more specifically, a method for forming a laser butt weld between opposing edges of a plate material formed in a cylindrical shape for manufacturing a can body or the like. The present invention relates to a method for continuously forming laser butt welds between opposing longitudinally extending edges to be welded.

[Prior Art 1] A method of forming a laser butt weld along opposing edges of two members has recently been developed by Sorin.
This is accomplished by the contacting welded edges being anchored together and moving relative to the laser beam, as disclosed in U.S. Pat. No. 4,152,573 by et al. Also, Nilsen
U.S. Pat. No. 4,354,090 discloses a 7-bar guide apparatus.
This has also been accomplished by guiding the opposing edges to be welded into substantial edge-to-edge contact with each other as shown in FIG. 2 for laser welding.

In both of these known laser welding techniques, the edge to be welded is usually a cut edge of a material, such as sheet metal, which extends essentially perpendicular to the plane of the material adjacent to the edge. Adjacent edges are arranged in contact with each other essentially through the entire thickness of the joint to form a closed butt joint.

The joint to be welded is welded by irradiating the joint with a laser beam from one side.

[Problems to be Solved by the Invention] There are the following problems in forming such a butt joint between two members lying almost on the same plane. That is, the member may be subject to problems along its length, particularly metallurgical problems and/or fluid flow problems known as slubbing.
), the problem is that when welding is performed at relatively high speeds and with minimal heat input due to the need to limit the amount of heat input, inconsistent or uneven welds are formed. . Transmission efficiency (transf) of laser energy moving across the welded edge along the length of the weld joint
One of the reasons why this problem occurs is due to fluctuations in the power efficiency. More specifically, it has been found that the presence of burr on the cut edge or edges to be welded contributes to the formation of the inconsistent weld. There is. That is, when a material such as sheet metal is cut, for example, a burr is typically formed on the cut surface that extends out of the plane of the sheet metal and along the direction of the cut. If the burr of the butt joint protrudes toward the side to be welded by the laser beam irradiated to the joint, the laser beam hitting the joint will collide with the burr and its energy will be scattered, causing the welding to occur. The transmission efficiency of the laser energy that should reach the edge is reduced. Furthermore, since the burr itself does not have as much tffi as the edge to be welded, it evaporates in a short time after coming into contact with the laser beam. This evaporation can roughly impede the transmission of laser energy to the welded edge and contribute to the generation of weld plasma at the location of the burr. The presence of plasma further reduces the efficiency of energy transfer to the edges. Therefore, the presence of intermittent and irregular burrs along the edges of the laser butt weld can lead to incomplete penetration and incomplete welds, especially when minimal heat input is used for welding. resulting in the formation of On the other hand, if the laser beam energy is increased enough to weld even in the presence of burrs, in areas where there are only a few burrs or where the burrs are not fully heated, it will be too high to form a normal weld. Heat will be input. This increases the extent of the weld and heat affected zone and also highlights the associated metallurgical problems and possible slubbing problems. In short, the presence of burrs causes defects in the weld and reduces the efficiency with which edges are successively laser butt welded.

Needless to say, the above problems can be avoided by grinding the cut surface to be welded to remove burrs prior to welding. However, this is undesirable because it adds extra manufacturing steps and therefore time and expense. Another possible solution is to arrange the burrs on the contacting edges in such a way that they occur outwardly on a surface opposite to that in the direction of the laser beam. Unfortunately, in many applications, due to the structure and function of the actual slitter or cutting device, the burrs generated on the cut edges of opposing materials are directed in opposite directions. This is also not a practical solution as it is extended. As a result, when the cut pieces are formed into a tube for butt welding, a welded joint is created that has burrs projecting from both sides.

It is an object of the present invention to avoid the disadvantages due to the presence of burrs on the surface of the weld joint that is first irradiated with the laser beam, and to reduce the contact edges while minimizing heat input problems such as slapping. An object of the present invention is to provide a method for forming a laser butt weld that performs effective and uniform welding at high speed.

It is further an object of the present invention to perform laser butt welding between opposing contact edges of two parts in order to enable a more efficient transfer of high energy to the workpiece by performing a high speed weld with a high heat input. The object of the present invention is to provide a method for forming a very fine and uniform welded part in which the heat-affected zone is relatively small and the welded part is continuously formed.

It is further an object of the present invention to keyhole weld contacting edges at high speed and with high efficiency in order to produce a weld having a relatively uniform cross-section throughout the thickness of the parts to be welded, by the method described above. The purpose is to provide a method.

[Means for Solving the Problems] The object of the present invention is achieved by the following method constituting the present invention. That is, two members to be butt welded are prepared, and the two members contact each other at a slight angle, that is, the butt joint formed by the edges is
arranging each edge of the member so that the edges are open toward a first side of the member and contact each other toward a second side of the member opposite the first side; and a laser beam directed at the butt joint from a first side of the members while pressing the edges of the two members toward the butt joint, the laser beam being directed at least partially toward the open side of the butt joint. This method consists of creating a butt weld in a butt joint by irradiating the butt joint with a high energy density laser beam that extends to the edge of the member.

[Operation and Examples] The method of the present invention is illustrated as follows by means of its preferred embodiments.

A butt weld between two members is made along the length of the edge of the member by moving at least one laser beam and another member relative to the direction of the butt joint to continuously weld the edges. Formed continuously.

In this embodiment, the two members consist of opposite sides of a single sheet of material. Preparing two members to be butt welded includes forming a cylindrical workpiece with a longitudinally flared edge to be butt welded from a sheet of sheet material. The step of locating each edge of said member comprises the step of moving said cylindrical workpiece over said Z-bar guide device until said edge contacts as described above by being guided by said device. include. The process further includes a support whose position on the Z-bar guide device can be adjusted such that when the cylindrical workpiece moves on the Z-bar guide device, opposite sides of the workpiece are slightly inclined to each other. supporting the workpiece by means. Although the previously disclosed cylindrical workpiece is usually cylindrical in cross section, the workpiece is provided with a two-bar guide device such that the workpiece has a slightly pear-shaped cross section due to the support means. is supported by That is, the opposite sides of the workpiece are inclined toward each other, and the edge to be welded is located above it so that the joint opens upwards. Because of this, any burrs on the said side (top side) of the fitting will be pulled outward from the center of the fitting, allowing the laser beam to be exposed to conditions with fewer or no obstructions compared to traditional methods. It becomes possible to make an injection.

In the embodiment described, the welded edges of the parts are cut essentially straight, almost perpendicular to the plane of the adjacent parts. Burrs are generated on the edges by the cutting action.

Thus, when the edges are positioned as disclosed in the present invention, the edges are mutually located on the first side of the member, as seen in a cross-sectional view taken across the edge (e.g., FIG. 1). , and come into point contact with each other essentially on said second side of the member.

Further, in accordance with the present invention, the high energy density laser beam preferably provides complete penetration along the butt joint performing the keyhole weld of the edge. In that case, an additional step of the method provides a laser beam dump on the second side of the component to absorb the laser beam passing through the butt joint during keyhole welding. This causes debris coming out of the keyhole (
In addition to collecting debris, it also prevents damage to the inside of can bodies and other cylindrical workpieces, for example. Also,
Prevent unnecessary reflection of laser energy. The use of such a laser beam dump enhances the safety of welding workers. The method may also alternatively provide means for accurately reflecting the laser beam through the butt joint and back to the joint to reduce the cooling rate.

When the laser beam passes completely through the butt joint and forms the keyhole, the molten edge material surrounds the keyhole. By welding two parts in the direction of a butt joint according to the present method, the fused edges are fused together immediately behind the keyhole as the keyhole and laser beam move over the parts in the direction of the butt joint. Ru.

A second embodiment of the invention includes a method of clamping a welded member in a welding jig by means of clamping the respective edges in contact as described above.

Hereinafter, the above and other features, features, and advantages of the present invention will be made clearer by description using the drawings. Note that the drawings illustratively represent two embodiments of the present invention.

FIG. 2 is a diagram of U.S. Pat.
, 354.090, showing the opposing contacting edges of the members (1) and ('2J) to be laser butt welded by the method disclosed in each of the documents. The edges to be welded (
3) and (4) show essentially straight cut edges extending perpendicular to the plane (5) of the respective member.

Furthermore, burrs (6) and (7) remain on the cut surface due to the cutting operation.

In the conventional laser welding of FIG. 2, the laser beam impinges on one side of the part from the direction of arrow (A) toward the butt joint, in this case on the top side of the joint. When the laser beam hits the upper burr (6), the laser beam light is suitably scattered by the presence of the burr and after a very short time the burr is heated and evaporates due to its small amount.

Therefore, the efficiency with which laser energy is transmitted to edges (3) and (4) decreases. That is, the incident laser energy is initially scattered by the burr and cannot be used for welding, and subsequent evaporation of the burr creates a welding plasma on the edges to be connected. The plasma and metal vapor at least partially impede the transmission of laser energy.

The effect of burrs during the welding process is due to the fact that the input of laser energy during welding, i.e. heat input, is a metallurgical problem that occurs when welding thin materials at high speeds to form can bodies, etc. This is especially true when the problem is keeping it to a minimum.

For a given laser beam energy focused on the edges to be continuously welded, the initial location along the weld joint may be unsatisfactory due to the varying size and location of the burr on the edges being connected. Although the weld is made, incomplete penetration or other weld defects may occur at other locations along the joint. Therefore, to form a full penetration weld along the entire length of the joint,
The minimum laser beam energy that should be used will be the welding energy required for the least efficient transfer of laser energy to the edge. Therefore, at locations along the weld joint where energy transfer is more efficient, excess unwanted heat is necessarily input during welding.

A metal cross-section of a butt joint is shown in FIG. 3 that has been laser welded in a conventional manner using a minimal amount of heat to effect a keyhole weld with edges arranged as in FIG. The weld (8) between adjacent edges in the figure has the shape of a wine glass, the widest side of which is on the top side of the joint and the narrowest side on the bottom side. This type of non-uniform weld geometry is problematic in certain cases. For example, in the manufacture of metal cans and other objects, the edges of the can must be rolled, necked-in, flanged on the outside, etc., so that the welds have uniform properties. desired.

In order to reduce or avoid the adverse effects of burrs on cut edges and the non-uniform weld properties that occur when the heat input for welding is limited to a minimum, the method shown in FIG. Detailed description of the invention. Member 01), 0'2J
The facing edges (9), □□□ are the two members 01)
, an OZ is open at the knee on a first side (top) of the member, and a second side (bottom) of the member opposite said first side.
The edges are placed in contact with each other so that the edges touch each other at the position marked ■. Laser butt welding is performed by directing the edges of the two members toward the butt joint and irradiating the butt joint with a high energy density laser beam. The laser beam extends from the first or upper side with at least a portion of the beam extending towards the edge (9) and the open side of the color, as shown by the arrow (B) in FIG.
into the butt joint, so that the In this way, the burr above the joint is pulled substantially to the left and right from the centerline of the joint, avoiding or reducing the effects of scattering and reducing the effects of burr evaporation. By extending at least a portion of the laser beam to the open side of the edge, heating occurs from the moment it hits the edge, as opposed to only the upper side in the prior art method described with reference to FIGS. This is done along all exposed edges to be welded.

In this manner, the method of the present invention achieves relatively uniform weld properties across the thickness of the parts being joined while minimizing heat input.

FIG. 4 shows a cross section of a welded portion formed by such keyhole laser butting. It can be seen that the weld width is relatively uniform throughout the thickness of the material.

a joint which is open towards the upper side of part 011.02), and in the lower position of the other, a third consisting of opposing edges (9), which essentially touch each other only at points; In the arrangement of Figure 1, the high energy density laser beam extending to the open side of the butt joint easily welds the edge contact area 0 and remains on the underside of the joint, forming a keyhole for welding. In a joint made by slightly tilting the member in this way, both edges are separated by a certain distance, and a filler (filter) is used.
In order to avoid adding a + material), it is necessary to press the edges of the two members while keeping the laser beam directed at the joint so that the edges of the two members are welded in the direction of butt. The forces applied in the direction of the joint are schematically indicated by arrows (C) and (D) in FIG. This force must be sufficient to effectively fuse the opposing molten edges of the laser keyhole welded parts together along the joint.

In continuous butt welding along the length of two members to be joined according to the present invention, a high energy density laser beam is irradiated onto the butt joint in order to perform keyhole welding along the joint, and the two members are joined in the direction of the butt joint. by arranging each edge of the member to move the at least one laser beam and other associated members in the direction of the joint to sequentially weld the edges in accordance with the method described above. are formed continuously. The amount of force that presses the members toward the butt joint must be sufficient to fuse the molten edges together without creating a significant upset in the joint.

The required force will vary depending on the thickness of the parts being joined, as will be readily understood by those skilled in the art.

According to a preferred embodiment of the invention, two butt welded
The two members are two opposing sides of a sheet of material formed into a cylindrical workpiece with opposing edges extending longitudinally. The edge is positioned for movement on the Z-bar guide device while being guided into the desired contact by the Z-bar guide device. A known seven-bar guide device and method for using it are described in U.S. Pat. No. 4,354,0.
No. 90 MVI, which is incorporated herein. Figure 5 shows a part of such a device.
and typically terminates at the adjacent laser welding equipment face. As shown in FIG. 5, the top of the center guide member and the top guide bar of the Z bar extend outwardly beyond the open end of the Z bar and beyond the weld point (-). cantilevered noseport
ton) 08. The circular open filling has a protrusion a
It is installed to penetrate through F3. The aperture is coaxial with the welding head (B) so that the energy beam (B) is focused onto the edge of the sheet material passing underneath. As mentioned,
A vertical barrier is provided to further limit relative vertical displacement of the edges of the sheet material.

The material used to manufacture the cans in the apparatus of FIG.
127~0.50 # (0,005~0.02 inch)
preferably about 0.203 mm (0,0
08 inch) thick 75 bond tin plate. The sheet material for making the can bodies is cut with conventional slitting equipment;
Therefore, as shown in FIGS. 1 and 3, a burr is formed that protrudes outward along the edge in the cutting direction. The cut material passes through a roll former, a feed bar of a can former, and is passed through a number of disposed rollers as shown in part in Figures 5, 6A, and 7A. Molded into a cylindrical shape. The guide (44) of Figures 6A and 7A is used in combination with rollers.

A longitudinally arranged sheet material is formed into a generally cylindrical shape by sliding the side edges of the sheet material and resting them in the grooves of the feed bar of the can forming machine. There are several combinations of octopus-like rollers and guides.

In addition to the means for forming the sheet material, there are several means provided for feeding the sheet material along the grooves and Z-bars of the former and through the weld. For this purpose, a conventional chain conveyor (chain-type
e conveyor), drive roller (drive
e roller), reciprocating piston (recil) rO
A catino 11iston or push rod can be used. However, for high speed welding, the apparatus disclosed in US Pat. No. 4,497,995 is preferred, the contents of which are incorporated herein.

The two-bar guide device of FIG. 5 operates according to the prior art;
The force of each sheet material is fed and formed into a general cylindrical shape as shown in Fig. 6A. In this case, the edges to be welded are in contact over the entire thickness of the material as shown in FIG. 6B, as discussed with reference to FIGS. 2 and 3. To carry out the method of the invention, the apparatus of FIG. 5 is modified,
Slightly lower the support roller ■ so that the upper support roller and guide move slightly inward. Accordingly, the 7th A
As shown in the figure in a slightly exaggerated manner, the shape of the cylindrical workpiece (2) has a shape somewhat similar to a pear shape. As a result, the edges to be welded are slightly inclined to each other as shown in FIG. 1 and FIG. 78, and the butt joint formed by the edges is opened toward the outside of the cylindrical workpiece.
touch each other inward. Furthermore, Figures 6B and 7B
In the figure, the members that sandwich the workpiece vertically are the upper guide bar of the Z bar 6 and the upper part of the central guide member of the 7 bar 6, respectively.

The shape of the upper guide bar is pointed at a slight angle in the case of FIG. 6B, whereas it is flat in the case of FIG. 7B. The planar shape of FIG. 7B allows for more stable and uniform guidance of inclined edges.

Preferably, the method of the invention also includes the additional step of providing a laser beam dump inside the cylindrical workpiece, which absorbs the energy of the laser beam passing through the butt joint during welding. This not only collects debris from the keyhole, but also protects the interior of the cylindrical workpiece from damage caused by laser energy during welding.

It also increases worker safety. As shown in FIGS. 8 and 9, the mandrel includes a laser beam dump Q4 for absorbing light from the laser beam (B) generated from the laser welding machine mouth. The mandrel is supported from the Z-bar by the joint bolts as shown in Figure 8.

The trailing portion of the mandrel cantilevers beyond the end of the two-bar guide. In this position, the mandrel extends inwardly and in the direction in which the workpiece moves along the two-bar guide through the laser welder.

The laser beam dump Q4 and the mandrel are located directly below the laser welding machine mouth and absorb the light from the laser beam (B). The laser welding machine is, for example, a 2Kll CO2 laser. The laser beam dump 04 includes a cup-shaped container (2) for receiving light. The cup is provided at the hole through which the light enters. The inside of the cup is painted in a dark color, preferably black, to absorb light. Most of the laser energy is absorbed by the beam dump, but
It is never absorbed with 100% efficiency. According to a preferred embodiment of the invention, the cup is made of an aluminum alloy that is anodized black on its inside. However, it may also be made of copper or other materials.

The container is cylindrical in shape and slides into an opening in a spool-shaped cooler tube placed within a mandrel.
(fit). The container is supported within the spool on a snap ring (2) which is received in a groove in the wall of the cylindrical opening in the center of the spool.

The spool closely surrounds the container with good thermal conductivity. Put thermal grease between the cooler and the container to increase the efficiency of heat transfer.

It is preferable. The spool is preferably made of copper for good heat conduction and corrosion resistance, and is cylindrical in shape so as to sit within a cylindrical hole formed in the mandrel. An annular coolant channel is formed around the outside of the spool. Coolant, such as water, is continuously supplied by inlet and outlet passages through the mandrel, as depicted in FIGS. 8 and 9.

O-ring encapsulation means (0-rin) on the opposite side of the flow path
g sealing member (31) effectively encloses the spool in a cylindrical hole for receiving cooling water. In another embodiment of the invention, the cooler is brazed into the hole. Details of the laser beam dump and mandrel are disclosed in US Pat. No. 4,436,979.

It is also incorporated herein.

In another embodiment of the invention, the method of the invention alternatively includes means for reflecting the laser beam by penetrating the joint and bouncing back onto the joint, thereby providing preheating and postheating and reducing the cooling rate. It can also be included. Reflection means for this purpose are schematically depicted as (32) below the joint in FIG. For example, a highly reflective surface provided on water-cooled steel can be used as the reflecting means. 1st
In FIG. 1 a further embodiment of the method of the invention is depicted. In the same figure, the tightening is done by tightening the members (35), (36) in the welding jig (37) by means (38) to (41) at the respective edges (33), (36) of the members.
4) are positioned so that they are in contact with each other. Relative movement between the laser beam and the workpiece in the welding jig occurs while continuously welding the longitudinal edges of the butt joint. The tangential forces indicated by arrows fE) and (F) in FIG. 11 act during welding to press the edges of the two members toward the butt joint as described above. The tightening force by means (38) to (41) is indicated by the arrow (G)
, (formerly shown in (I) and (J)). A generally cylindrical workpiece to be welded using the method of the invention by the apparatus of FIGS. 5, 7A and 7B. n
The forces acting on are shown schematically in FIG. The roller ■, which supports the workpiece in a generally cylindrical shape, although somewhat pear-shaped, is supported by a spring (42
) are held down respectively. That is, the 10th
In the figure, forces (Fl), (F2), (F6), (Fl) and (F8) are acting on the cylindrical workpiece towards part 6. The guide (44) is placed against the workpiece (F9), (
Flo). Protrusions OF3 extending from the Z-bars on either side of the weld area provide a vertical barrier against relative vertical displacement of the edges of the sheet material, so that the upper surface of the edges of the parts are maintained before and after welding. is in continuous contact with. The radially directed force (F3) shown schematically in FIG. 10 represents the effect of the protrusion in this regard. If there were no protrusion or guide (44), the free end of the part to be welded would be lifted upward by the restoring forces of the workpiece material. The radial force on the cylindrical workpiece induces a tangential force (F4), (F5) that directs the edges of the two members toward the butt joint (43). Therefore, when melted by keyhole welding of the laser beam through the joint and displacement of the lower contact of the edges occurs, the opposing melted edges will be affected by the force (F4) and (F4)
5) brings them closer to each other and practically fuses together.
be done. The molten edges become fused after the keyhole formed as the laser beam moves along the butt joint to successively weld the pieces together.

An example in which the method of the present invention is actually applied will be explained.

In general, cylindrical can bodies are shown in Figures 5, 7A, and 7B.
Laser butt welding was performed using the equipment shown in the figure.

Steel sheet material 0.2031111 (0.008 inch) thick was used to form the can body. The cut edges on opposite sides of the cylindrical workpiece were placed in contact using a two-bar guide device 6. The two ends of the workpiece are tilted to each other at an angle α-17°, and the butt joint formed on the cut edge extends d-0,051 mm (0,0
02 inches). Here d is the first
This is the distance between both open edges in the figure. 2k14
The laser beam generated from a CO2 gas laser has an energy density of at least 10' W/ci and a surface area of 0.076 to 0.102 mm (0.003 to 0.0
In order to perform continuous keyhole welding in the longitudinal direction of the can-body joint, which had a beam width of 0.04 inch) and moved at a speed of 30 m/min, the butt joint was irradiated by the laser welding machine mouth. The weld formed well along the length of the joint despite the presence of burrs on the cut edges, resulting in a relatively uniform weld cross-sectional shape at both the top and bottom. The cross-sectional opening of the welded portion (45) is shown in FIG. As will be readily understood by those skilled in the art, butt welding can be performed using the method of the present invention even when plate materials have different thicknesses and workpiece shapes differ from those of the present embodiment. The angle α formed by the opposing edges may have a value different from that in this example, but it should be such that the open joint does not exceed the maximum diameter of the laser beam passing through it, regardless of the thickness of the material to be welded. It is preferable to take This results in
Pulling any burrs away from the centerline of the joint allows sufficient laser energy to enter the open joint and directly strike the opposing edges.

Although only two embodiments of the present invention have been shown and described above, the present invention is not limited thereto and can be modified in various ways known in the art. For example, it is also conceivable to apply the method of the invention to other island energy density welding methods in which a beam of energy is applied to the workpiece. The method of the invention is therefore also useful with beams such as, for example, high energy density welding beams. Also, although in the disclosed example the materials to be welded were thin sheet materials, the method of the present invention can also be applied to thicker or non-metallic materials, such as plastic parts. When welding parts, several laser beams can also be used on the same or opposite sides of the weld joint. Accordingly, the present invention is not limited to the details shown and described herein, but is intended to include all such changes and modifications.

Advantages of the Invention In particular, the method of the invention avoids the conventional problem of forming irregular welds as a result of the presence of burrs on the edges of cut workpieces. In addition, welding plasma is generated not only on the upper side of the workpiece where the laser beam first strikes, but also on the opposite side, resulting in more efficient and uniform heat distribution, resulting in more efficient welding. The added benefit of increasing the The method of the present invention also provides a reduction in heat input associated with metallurgical problems such as slabbing and damage of the base material in the heat affected zone adjacent to the weld material. This method also assists in keyhole formation of the laser beam through the weld joint, creating a weld of more uniform nature or shape.

Even highly reflective material surfaces do not need to be masked or removed for laser welding, as the reflected laser energy becomes trapped within the open joint. The method of the invention thus enables high speed laser butt welding, for example, where the contact edges are welded at a rate of 15 to 751 per minute.

[Brief explanation of drawings]

FIG. 1 is an enlarged side view showing the edges of two parts being laser butt welded according to the method of the present invention. In the diagram, 2
The two parts are slightly inclined to each other and the joint to be butt welded at the welded edge is open towards the first side of the part. The edges contact each other toward a second side of the member opposite the first side. FIG. 2 is an enlarged side view showing the edges of two parts with a conventional butt joint for laser welding according to the prior art. FIG. 3 is a 100 times enlarged cross-sectional view transverse to the welding direction of a laser butt weld in a member according to the prior art. FIG. 4 is a 100 times enlarged cross-sectional view across the welding direction of a welded laser butt joint according to the invention. FIG. 5 is a side view of an apparatus for laser butt welding opposing contact edges of a longitudinally extending weld joint provided on a can body or other cylindrical member according to the present invention; It is shown. FIG. 6A is a cross-sectional view of the device of FIG. 5 along line I--I according to a prior art method. FIG. 6B is an enlarged cross-sectional view taken along line n-II of the apparatus of FIG. 5, illustrating a conventional technique for bringing edges into contact for laser welding. FIG. 7A is a cross-sectional view similar to FIG. 6A, but for continuous laser butt welding according to the method of the present invention.
6 shows cross-sections of the device of FIG. 5 under different conditions; FIG. 7B is a cross-sectional view similar to FIG. 6B, but showing opposing contact edges welded by the method of the present invention, placed by the modified apparatus of FIG. 7A. Figure 8 shows the two-bar guide of Figure 5 with the mandrel supported on the underlying surface and through which the laser beam dump can be moved to absorb laser energy as it penetrates the edge to be welded during keyhole welding. FIG. 2 is a side view of the device, a portion of which is shown in cross section. FIG. 9 is a cross-sectional view of the device of FIG. 8 taken along line -■. FIG. 10 is a schematic representation of the forces applied to a cylindrical workpiece whose edges are laser welded by the method of the present invention, the forces being effectively applied to opposing, contacting edges, the edges forming a butt joint; Welded in the direction of FIG. 11 is a view similar to FIG. 1, but showing the means for tightening the respective edges in the welding jig of two members slightly inclined to each other to be laser welded by the method of the present invention. ing. FIG. 12 is an enlarged cross-sectional view across a weld formed by the method of the present invention. (Main symbols in the drawing) (6), (7): Burr (9), (To): Edge 01), 021 = Member (13: Contact point guide device (221: Workpiece (24 = Laser beam dump ( 32): Reflection means (37): Welding jig (38) to (41): Tightening means (B): Laser beam Patent applicant Nis.D.B. Figure 10 Figure 11

Claims (1)

[Claims] 1. Two members to be butt welded are prepared, and longitudinally extending edges of the two members to be butt welded, which are slightly inclined to each other, are arranged so that they are in contact with each other. irradiating the butt joint with at least one high-energy-density laser beam from a first side of the member in a direction perpendicular to the longitudinal extension of the edges formed by the contacting edges; a butt joint opening toward a first side of the member in a direction perpendicular to the longitudinal extent of the edge, the abutting edge of the butt joint being opposite the first side; the butt joint of the edges of the two parts being in contact with each other towards a second side, and at least a portion of the laser beam being pressed in the direction of the butt joint when butt welding the parts; A laser butt welding method characterized by extending toward the open side. 2 the butt weld is continuously formed by moving at least one of the laser beams along the length of the edge, and the members are mutually bonded to each other in the direction along the edge; 2. A method according to claim 1, wherein the welding is performed continuously. 3. The method of claim 2, wherein the two members are opposite sides of a sheet of material formed into a cylindrical workpiece having longitudinally extending opposite edges that are butt welded. . 4. The method of claim 3, wherein the method of locating the edge includes moving the cylindrical workpiece over a guide device and guiding the edge into contact by the guide device. 5. said cylindrical workpiece is supported by support means as it moves over said guide device, the position of said support means being adjusted with respect to said guide device such that opposite sides of said workpiece are slightly inclined relative to each other; 4. The method according to claim 4. 6. Said cylindrical workpiece is generally cylindrical in cross-section and its upper edges are tilted toward each other on opposite sides of said workpiece and said workpiece is opened on the upper side of said workpiece. 6. A method as claimed in claim 5, in which the guide device is supported by the support means such that the cross section has a cross-section somewhat resembling a pear shape. 7. The method of claim 1, wherein the high energy density laser beam performs a keyhole weld of the edge completely penetrating the butt joint during welding. 8. The method of claim 7 including the additional step of providing a laser beam dump on the second side of the member to absorb the laser beam that penetrates the butt joint during welding. 9. Providing in the vicinity of the second side of the component means for reflecting the laser beam passing through the butt weld back onto the joint in order to slow down its cooling by preheating and/or postheating the component. 8. The method according to claim 7, comprising the steps of: 10 the edge of said member is an essentially straight cut edge leaving a burr caused by the cutting action, and on a cross-section across said edge the first
2. A method as claimed in claim 1, in which the members are positioned in essentially point contact on a second side of the member, moving gradually apart from each other in a direction towards the sides of the member. 11. The method of claim 1, wherein the members are moved over a guide device such that respective edges of the members are positioned in contact. 12. The method of claim 1, wherein the method of bringing respective edges of the members into contact includes clamping the members within a welding jig by clamping means. 13. The method of claim 1, wherein said member is formed from sheet material. 14. Two parts to be butt welded are provided, the longitudinally extending edges of each of said two parts to be butt welded at a slight angle to each other are arranged so that they touch each other, and at least one height irradiating the butt joint with an energy density laser beam while moving the at least one laser beam and the member relative to each other in a direction along the butt joint in order to continuously butt weld the members; a butt joint formed by the contacting edges is opened toward the first side of the member in a direction perpendicular to the longitudinal extension of the edges; are in contact with each other towards a second side of the member opposite the side of the member, and the laser beam is directed from the first side of the member towards the joint perpendicular to the longitudinal extent of the edge. 2, with at least a portion of the laser beam extending toward the open side of the butt joint, completely penetrating the butt joint and forming a keyhole with the molten member around it; The two parts are pressurized in the direction of the butt joint during welding, causing melting of the part immediately after the keyhole as the keyhole and laser beam move relative to the part in the direction of the butt joint. A laser butt welding method in which the edges of the edges are fused together. 15. Claim 1, wherein said members move on a guide device so as to bring their respective edges into abutting contact.
The method described in Section 4. 16. The method of claim 15, wherein the two members are opposite sides of a sheet of material formed into a cylindrical workpiece having longitudinally extending opposing edges that are butt welded. . 17. Said cylindrical workpiece is supported by support means when moving on said guide device, the position of said support means being adjustable with respect to said guide device such that opposite sides of said workpiece are slightly inclined relative to each other. A method according to claim 16. 18. The cylindrical workpiece is generally cylindrical in cross-section, and the upper edges of the workpiece are tilted toward each other by tilting opposite sides of the workpiece and opening the joint on the upper side of the workpiece. Claim 17 supported by said support means on said guide device so as to have a cross-section somewhat resembling a pear-shape.
The method described in section. 19. Two parts to be butt welded are provided, the longitudinally extending edges of each of said two parts to be butt welded at a slight angle to each other are arranged so that they are in contact with each other, and at least one height irradiating the butt joint with an energy density beam from a first side of the member in a direction perpendicular to the longitudinal extent of the edges, the butt joint formed by the abutting edges towards a second side of the member, the edges being open in a direction perpendicular to the longitudinal extent towards the first side, and the contacting edge of the butt joint being opposite to the first side; in contact with each other, at least a portion of the beam extending towards the open side of the butt joint of the edges of the two parts that are pressed in the direction of the butt joint during butt welding of the parts. A butt welding method that is characterized by 20. The method of claim 19, wherein the high energy density beam is a laser beam.