JPS59206190A - 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 The present invention relates to the welding of metals, generally ferrous metals, in the form of structural members and to improvements in factory layout and practices using this welding technique.

BACKGROUND OF THE INVENTION Welding of butt edges of metal plates, or butt welding, is commonly accomplished by moving a welding arc along the adjacent upper edges of the plates to melt the material. However, since the depth of melting (penetration) is limited, in the case of thick plates, it is necessary to weld the other side of the plates to be joined.

This involves picking up and inverting the partially joined plates before the first run (this can cause damage).

(which may require expensive lane equipment) and by making the ath run from the bottom of the plate (which is a slower and more dangerous operation for the welder). In the case of a particularly thick plate, composite penetration alone is insufficient, and as a preliminary operation, grooves were formed at the upper and lower edges of the plate edge (lI
) Perform welding using filler material in the V-shaped groove.

Another common welding requirement is to weld seven plates to another plate in a roughly orthogonal configuration. This is typically done by forming a weld fillet along each inside corner, which also requires several runs. If the plate is thick, it may be necessary to form grooves at the corners of the plate to be welded. Similar techniques are used to secure roll-formed or manufactured formations to plates.

Laser beams are a convenient and known means for cutting a variety of materials. The use of laser cutting has been suggested for relatively thin plates or sheets to provide a clean cut with minimal thermal stress on the sheet.

Powerful laser beams are considered as an energy source in welding processes because of their potential deep penetration. However, the experimental results of laser welding on relatively thick iron-based materials were not necessarily satisfactory. In particular, it has been found necessary to cut the edges to be welded in the absence of oxygen and then to clean and machine these edges so that they fit in close contact along their entire length. did. Welding is only possible under these laboratory conditions.

In shipbuilding and other heavy industry factory practices.

It is known that laboratory conditions are not achieved and laser welding experiments are unsuccessful. The reason for this is thought to be the condition of the edges of the plate. First, the cut edges are
It's not straight, but somewhat curved. Second, the cut usually has a somewhat oxidized surface with rough ribs or striations extending perpendicular to the surface of the board. This can be oxygen fuel or laser
This is due to the disturbance when the plate was first cut to size using gas. For these reasons, 1 width/~, 2 m
Regular or random gaps of m may occur between the abutting surfaces. Any powerful laser beam must be very closely focused or focused (less than 7 degrees) to transmit enough energy to melt a pool of molten material.

e.g. o, rw or less) and gaps of the size seen in practice will initiate melting with the focused part of the beam not making contact with the metal or only contacting it above or below the focal point. There are areas where it is not allowed.

Surprisingly, the inventor of the present invention was able to weld by only operating from one side of the plate, without extensive adjustment of the plate parts in contact, and by making full use of the deep penetration characteristic of the laser beam, the shipbuilding We have found a method for laser welding metal, especially ferrous metal plates, which can be easily applied under other working conditions.

The present invention provides a method for welding parts of metal sheets together, with the cuts or shapes to be welded in as close contact as their surfaces will allow, using a focused or focused high-energy laser beam. Moving along said line of best contact, at the focal point of the laser beam, another familiar material is placed that intercepts the beam, and on said beam intercepting material, said (ri) condensing material is placed. welding characterized in that a quantity of gas is directed to the focal point of the laser beam in order to at least partially confine the plasma formed by the impingement of the laser beams. provide a method.

The surface of the part to be welded does not need to be specially adjusted beyond cutting, rolling or rolling, but the present invention is of course applicable to any case where this adjustment has been made.

Usually both the plates and the material blocking the beam are made of ferrous metals. The term "plate" as applied to ferrous metals means at least three dimensions thick. The "familiar" metal may be of the same composition as the plate, but is typically a slightly different alloy with the same properties.

In operation of the method, a plasma is formed whether or not any part of the plate blocks the focused beam, at least from the material that blocks the beam.

What gas is supplied?

The plasma is directed to a predetermined area, at least enough to cooperate with the laser beam in an amount sufficient to transfer energy to the surfaces of the plates on either side of the gap, but not so much as to block the beam above the level of the weld. hold in position. The actual gas supply pattern can be adjusted by the operator in terms of beam width and weld pool size. In practice, uncut thermally cut or laser cut edges from 3 to 3 inches thick can be welded to their full depth in seven passes using the laser technique. If desired, this welding may be repeated on the underside, and laser techniques are useful for either "downhand" or "uphand" vertical or horizontal welding.

The material blocking the beam is theoretically a powdered or particulate material that fills a gap and is held in place by a welded backing piece. However, this is not preferred and it is more preferred to supply the material during welding so that the required amount can be controlled. One way to do this is to feed a grain of material into the focal area, but it is preferred to feed a feed wire into the focal area to block the beam.

The wire is usually fed from the front of the weld, but the reverse is also possible.

A distinction is made between the integration of the welding filler wire and the wire blocking the beam. Weld filler wire is commonly used to supplement or change the composition of the metal in the weld. The wire is placed in the weld line at the weld point, but the energy transfer is non-selective from the energy source to the weld surface and the wire so that both co-fuse. According to the invention, the use of filler wire itself is not suitable. Any wire must be precisely positioned with respect to the focal point so that if a gap occurs, vaporization of the wire and formation of a plasma will occur around the seam, allowing energy to be transferred to the points to be joined together. Ru.

The method of the present invention is easily used for butt welding as described above, and in addition, from the negative side, in 7 passes.

It is also useful for forming a weld between the stem and head of a T-weld if desired. actually.

The axis of the laser beam is below so0, more commonly
SO~/! Enter one side of the desired weld line at an angle r0,
The beam is focused or focused onto a beam blocking member on or just inside the outer surface of the plates to be joined. Similarly, a T-weld is formed in this way, where the stem has a rolled edge rather than a cut edge.

/7/1傛-] 7/77/'/' (//) Using too large an angle usually means that both inside corners need to be welded.

This is perfectly acceptable, but the special advantages of the inventive path are of course lost.

The present invention is a workstation device for use in assembly by welding metal sheets, such as steel sheets, comprising at least a such stations at separate locations in the flow chain of the workpieces, each The station is
a movable laser beam focusing head that can be selectively optically coupled to the optical path of an intense laser beam generator common to the one or more workstations;
The two workstations are welding stations that use the welding techniques described above.

The at least one workstation may be a laser cutting station, for example for initial cutting and trimming. Laser cutting is a well-known technique for a variety of materials and is advantageously used to cut thin ferrous metal sheets to reduce distortion due to thermal cutting.

Typically up to five welding stations may be used. Five is the preferred maximum, although a higher number is theoretically possible (since in use any one station disables the other stations).

Selective optical coupling to the generated beam is achieved by "moving optics". It is not appropriate to move large gauge or thick steel plates so that the butt (weld) line passes through a stationary focused laser beam. Similarly, high energy (S-co5ki) generators of laser beams are heavy, expensive and also cannot be moved along the weld line. Therefore, typical configurations according to the invention include (a)
(b) one or more angled laser beam mirrors disposed at or more positions, and (c) an equal number of movable focusing heads; each said focusing head comprises another angled laser beam mirror and focusing means for focusing the beam onto a small cross-section, by selectively interposing the angled mirror in the generated beam;
The beam is deflected to a focusing Radomirror and then further to said focusing means.

The angled mirror, which can be selectively interposed in the main beam, is itself movable in the longitudinal direction of the beam. The angled mirror on the focusing head may itself be a focusing mirror and form the focusing means or part thereof, especially if the laser power is relatively high. A typical sequence of operations is: (1) Laser cut the first board, (II)! Laser butt welded the first plate unit into 7 panels (il+)
To fit the reinforcing bar to the panel, laser "skid" welding was performed using the same barring means.
The same laser skid welding technique may include securing large spacing of girders across the bars and panels.

Fitting a reinforcing bar to the bottom surface of the panel, process (1) ~
The through-weld technique according to a pending patent application based on UK application no.

The invention will now be described in more detail with reference to the accompanying drawings.

In FIG. S, one plate /, - is shown in theoretically perfect alignment along line 3.

A laser beam beam enters this line 3 and is focused directly below the surface. The energy of the beam vaporizes a keyway-shaped section S through the material, and the vapor pressure in this section S supports the molten wall 6.

In reality, the vapor will not be able to escape from the keyway S and will form a laser-blocking plasma by means of a controlled jet of helium (see FIG. 1). As the piece moves along the seam, the keyway-shaped portion S moves. This is because Peemda dissolves the existing keyway portion 57t, and the material solidifies behind it. A deep penetration weld is usually formed in one pass.

Fig. 1 shows the welding method according to the present invention <15;
) is a schematic cross-sectional view along the welding line of the main part of the device that can be used for.

The laser beam 7 enters the wire /J slightly above the focal point /I. The wire 2 is continuously fed through a wire feed nozzle 9 by a feed roll driven by an electric motor (not shown). If desired, the feed of the wire saw can be related to the speed of movement of the welding pass and/or to the measurement of the actual gap between the plates /, J, for example by a gap sensor in front of the welding point. Can be done.

Wire saws cut the board/,! Even if there is a lateral gap between them, they will be vaporized by the incidence of the laser beam 7. The metal in the wire saw vaporizes and forms plasma.

The gas supply hood j is connected to the bottom passageway/41. in a gas flow condition confining the plasma. A shielding gas, usually containing helium, is supplied via the central duct h/, and the peripheral duct /6.

British Patent No. 139/? No. 93 discloses a typical feed hood in detail. When this plasma beam collides with the IO, energy is absorbed and transferred to the surrounding gold, forming a continuous molten wall/9 (the wall 19 defines a keyway-shaped portion: IO). , gradually solidifies as welded part-7).

FIG. 3 conceptually illustrates the technique according to the present invention on an enlarged scale in a cross-sectional view perpendicular to the plane of the paper of FIG. The beam 7 impinges on the wire/J to form a plasma 7a, which is held in the gap by a gas supply (not shown) and is not completely blown away, but stays at the top of the gap and generates a laser beam. Nor does it prevent the beam from reaching the wire l- (which blocks the laser) with sufficient strength.

Figure 3a is an h-plane view of a weld that is often (but not always) formed using this technique (depending on thickness, gap, speed, material, etc.).

In this cross-sectional view, C/a is the "conducting bowl" area with the number "6" circled. At the actual focal point there is a slightly narrower constricted region, 21b, and a wider bottom region 1c, where the beam spreads out again, but only enough to keep the weld material melted. It has strength.

Laser welding as described above produces significantly less thermal distortion in the welded object than prior art methods. It has been found that when applying the welding method according to the invention, there is a wide latitude regarding the main parameters such as focus position, filler feed rate, seam tracking, ie the overall seam line.

In FIG. 9, a typical butt weld according to the present invention is shown in cross-section. This weld has the characteristic cross-sectional shape of the bath metal, 22, being wider at the top than at the bottom and slightly bulging before tapering towards the bottom. On either side of the weld metal are two similarly tapered regions of heat-affected metal; A T-shaped weld (referred to as a skid weld) according to the invention with a weld metal zone and a heat-affected zone is shown. The weld shown in Figure S is formed in one pass using a device similar to that shown in Figure 2, except that the laser beam angle is 50 to 5' to the direction shown in the figure. , - so as to be able to enter the gap between them.

Thus, according to the present invention, a skid weld can be formed even for a poorly aligned seam by introducing the wire so as to impinge on the beam body, as in the case of a flat butt weld configuration. The wire/co may also provide filler, but may also be used to modify the metallurgical composition of the weld.

Although this skid welding technique typically forms a sound connection in one pass from one side, a first pass from the other side may be used.

Figure 6a shows a practical example of the hardness characteristics of a T-weld formed in one pass between (lγ) two similar plates, each with a thickness of 6, with an air laser cut edge. have,
This is 0 from the surface. ．． Using impingement wires spaced 711θ and of the same kind of material, the moving speed of the weld is Ant
/second. The figure shows a Vickers pyramid stiffness display using a skg load.

Figure 6b is a similar diagram using a welding speed of 11117 seconds.

Figure 6d shows welds on both sides (l pass on the - side), with 0.
With a spacing of 3a, the respective speeds on the 6 dragon oxygen laser cutting edges are 7.2111/sec and /41 frames/sec.

Figure 7 shows different techniques of laser welding in cross section,
Although this itself is not in accordance with the invention, UK application No. 3 106
No. 3θ, a pending patent application filed on the same date. According to this alternative method, the weld, e.g. , no blocking means such as the impingement wires used in the present invention are used. The inventor is
It has been found that the above-mentioned invention can be utilized on a production line in connection with the welding technology of the present invention to be used for manufacturing by welding large multi-weld units and bring benefits to the entire equipment and process. The second prisoner is similar to Figure 7 and has the same type of "Through Weld" 3.
3 (joining plates 3Q, 3!) is shown.

However, in this case the skid weld 36 according to the invention is
A plate 37 is further joined at right angles to the plate 3S.

FIG. 2 shows a typical composite panel product, to which the welding technique according to the invention is applied. This product has a flat /J audience plate of 3t, which itself is made of butt-welded steel as shown in Figure 2. Illustrated as. Stiffeners 39 (five in the illustrated example) are welded to one surface of the plate 3r, and each stiffener has a fifth stiffener.
It is welded to the plate 3j along its length using the technique shown. Deep webs 4to are welded across the stiffener 39, these webs contacting both plates 3t and the stiffener 3de (at least on one side of the recess lθa). Weld at these contact lines by the technique of Figure S.

A deep web θ typically has a rolled upper edge θa for reasons explained below.

In this example, the length of the panel is 1Offl, and the width is m.

The total weld length IfOm of the stiffener seam and the corresponding length of the deep web seam 30 m.

Figure 10 shows a fixed gun moving along the line Dada to join the adjacent edges of the metal piece DADA3)
It is shown how to install the apparatus for producing butt welds (Fig. 3, 3) on the IJ-.

The gantry is equipped with a support leg 1/ that supports a hollow crosspiece 11k for moving the transverse carriage II6 along it. At one protruding end of the crosspiece 13 there is an angled mirror 7 for blocking the laser beam lIt that has not reached the focal point (this will be explained below) and reflecting it along the inside of the crosspiece IIS. ◇Another angled mirror t moves with the transverse carrier and is placed in the transverse member lIS to always intercept the reflected laser beam and reflect it downward into the stem jO, and another mirror in the swivel focus head 341 In S-, 33 there is a wire which acts to interrupt the beam focal point in the gap between the zero plates 4tJ, 4(J), which orients the adjustment part 3 according to the height and thus produces a focused beam at the exit 35. A wire supply mechanism SA is also attached to the stem S[theta] to constantly supply the S[theta].

7th QB, the figure shows outlet 3 with gas supply duct 57!
Showing possible forms of r, duct! The wire feed guide 39 is placed on one side of the focused beam 3g and the wire feed guide 39 on the other side, giving a compact configuration.

Figure 11 is the ! i, Aa-6C shows a welding device according to the invention for obtaining the welds shown in Figures 6C, which device is mounted on a movable gun) IJ-;

The movable gun (IJ-) includes a support leg 60 that is movable along the rail A/K, and has an angular shape at the protruding end to block the unfocused laser beam 6da like the beam lIt, as shown in FIG. A horizontal carriage t3 that is movable together with 0 horizontal members supporting 6 horizontal members equipped with mirrors 63
supports an angled mirror A6 in the crosspiece to further deflect the laser beam. To accommodate the additional movement possibilities, a multi-axis robot arm A6 (swivel focus head 54t in Figure 1O) A flexible laser beam guide is provided inside the robot arm terminating in the focus head Aff, and the focus head At is The wire is fed from the member 6? and the gas supply as shown in FIG. It is given by the movement of IJ-, the movement of the lateral carriage, and the movement about the axis of the robot arm.

The apparatus of Figures 10 and 11 can be incorporated into equipment for manufacturing improved welds of composite panels or similar structures. This is shown in Figure 1. Before considering Figure 1j, it is necessary to evaluate the nature of the prior art method. Typical known configurations of basic panel construction for use in ship construction include the following layout:

(a) Initial trimming and preparation stage for checking the board received from the supplier for size and performing the required trimming. At this stage, for the assembly of the desired number of plates, selected plate edges are chamfered to facilitate weld penetration during later butt welding of two such plate edges.

(1)) conveying the board from one stage to the next on a series of supports comprising spaced apart parallel lateral rollers;
Perform welding in several stages.

A typical welding sequence includes:

(1) To form one large board of desired size,
Butt weld several trimmed plates. Usually three, one or three such plates are butted together, first along the top of the butt plane, by the welder controlling the welding tool across the plates, and then along the bottom line, by heat welding or arc welding. Weld. This latter step can be done by "up-hand" welding or by inverting the half-welded plates (the latter requiring expensive lane equipment and risking accidents).

(11) At right angles to the first butt weld or from this to 3θ
θ T-welds or other methods for attaching stiffeners or reinforcement plates. Typically 10
The plates are welded along their entire length (at the rolled edges, if any). Additionally, typically one welding bath is used for each plate, one along each side edge.

(iii) Weld one or more substantially deep web structures to the plate and bar in a 90' orientation to the bar, as these can reach more than /rn onto the plate and allow welding to a single structure; The lower edge is formed with a cutout portion that receives the stiffening bar and is formed to contact at least a portion (eg, the negative side) of the bar.

(iv) (when double skin panel is covered),
Steps (1), (+1)
) and weld it in place. The main deep web is sandwiched between and separating one assembled reinforcing panel. The necessary welding is done from the "crawl space" thus created,
It is an unpleasant and costly task.

As such, complex lane equipment, multiple welding stations with separate equipment, and expensive and dangerous welding techniques are required.
All are included in this typical structure. Another feature of the equipment is that thermal distortion, which requires expensive lamps or straightening equipment, can actually occur during welding. Figure 1 shows an aspect of the invention for composite panels produced in welding. Shows the production line according to. This example includes three in-line workstations I-4 serviced by a common overhead crane for simple transfer motion (schematically indicated by RI θ) and a common laser facility 71. The in width is typically suitable for boards up to maximum size.

Station I includes a magnetic bed wolfberry supporting a plate (not shown) whose grade is on the inspection pit wolfberry;
Butt a similar piece along a line perpendicular to the production direction, just below the gantry as shown in Figure 0. The laser beam lIg in Figure 10 reaches the gantry as shown and the movement of the lateral carrier O is directed to the butt line in order to perform welding and focus the beam as shown in Figure J.7.41. Support the welding head along. A large number of strips can thus be incorporated into one plate 3g (see FIG. 7). This station I may, if necessary, have rollers for movement in the line direction, and the same can be done for the other stations if desired.

Station ■ itself is attached to a turntable and held at γt. It is equipped with a conventional rail-mounted transverse arc support arm 5 for initially tack welding the metal fitting 3 across the butt weld plate. The turntable allows the stiffener to be positioned across or parallel to the initial butt weld (FIG. 9).

Station (2) includes a movable gantry shown in FIG. The laser beam X+ travels along the crosspiece 6.2 to the horizontal carriage t! The laser beam is then deflected toward the focus head 6g and downwardly of the robot arm in a laser beam guide. This station allows stiffener 3
9 (the tacking is already fixed by welding) can be welded to the plate 3j as shown in FIG.

The movements of the gantry, lateral carriage and robot arm follow the required weld line.

Station ■ is similar to station ■, but the gantry, lateral carriage and robot arm move differently to weld the deep web 4to fed by the crane 70 to the previous assembly.

Station V is a conventional inspection, repair and loadout station.

Laser equipment? The properties of / are generally self-evident.

Typically, a t □ KW laser microscope 7 is used with a beam expander 7S to combine the beam before outward deflection and direct the beam to the beam path 4Zf.
, 64 (and can be interrupted by the mirror mirror 7.3). The various mirrors can be controlled to be selectively positioned in or moved from the unfocused beam path. .

The presence of heavy duty laser equipment for the welding procedure according to the invention on the line of FIG. 72 allows the incorporation of further equipment or stations. For example, by extending the outer laser beam lIt in the direction of arrow A,
The beam is appropriately reflected and focused to perform a pre-cutting or trimming step (not shown) on the steel billet obtained from the supplier. Laser cutting is a known expedient, and a beam powerful enough for welding purposes is well suited for (31) cutting.

FIG. 73 schematically shows the operations carried out in another manufacturing process conceptually interposed between stations ① and ②. The composite panel of Figure 7 can itself be welded (with a deep web rolled edge θa) to another plate 3g, 39 to produce a double skin panel, which is a standard structural unit of ships. I can do it. The gantry shown in Fig. 1/i (or perhaps the gantry with the turntable).

The "through-weld" shown in FIG. 79g (described in the above-cited pending prior application) can be easily fabricated using the gantry shown in the figure) and an extra laser beam path to feed the focus head. It can be formed along the dotted lines using the downward welding technique. In this way, there is no need to use welding equipment in confined, inconvenient spaces or use expensive and dangerous overhand welding.
This standard unit can be manufactured on a production line.

[Brief explanation of drawings]

(3 items) Figure 1 is a perspective view showing theoretical laser welding of three plates in one pass from above, and Figure 2 is a perspective view showing one form of welding device according to the present invention along the welding line. FIG. 3 is an explanatory diagram showing the laser beam colliding with the interfering wire in the gap between the plates to be welded; FIG. The figure is a cross-sectional view of a butt weld formed according to the method of the present invention, and FIG. S is a cross-sectional view of a T-weld formed according to the method of the present invention. Figure 40 is an illustration showing hardness value readings across three exemplary weld cross-sections; Figure 7 is a cross-sectional view of a weld obtained using different techniques of laser welding; FIG. 9 is a perspective view of a welded bottom panel used in the construction of ships; FIG. 70 is a cross-sectional view showing a weld obtained using a technique similar to that of FIG. FIG. 1 is a perspective view showing a fixed gantry supporting a welding assembly suitable for obtaining the weld shown in FIG. Especially the t, x
Another movable gun supporting an assembly suitable for obtaining the weld shown in Figures a-xc) IJ- in a perspective view, 1st.
FIG. 2 is a perspective view showing a production line using the laser welding technique according to the present invention, and FIG. 73 is a schematic perspective view showing welding of a double skin panel. Explanation of symbols l, Koni plate, tick laser beam, 17 = focal point, l Koni wire. (3ri

Claims (1)

[Claims] l A method for welding parts of metal sheets together, with the cut parts or shapes to be welded in as close a contact as their surfaces will permit, in which the Move the laser beam along the line of best contact until it is at the focal point of the laser beam. arranging another material that blocks the beam, and at least partially confines the plasma formed at least partially by the impact of the focused beam on the beam blocking material; A welding method characterized in that a beneficial quantity of gas is directed into the focal point of a laser beam. The welding method according to claim 1, wherein the metal plate has a thickness of 3 to 13 mm. j,! The welding method according to claim 1, characterized in that welding is performed in seven passes using a laser beam of -, 2 left KW. A welding method according to claim 1 or claim 2, characterized in that the weld line is a weld line of a butt weld between generally a series of adjacent plate edges. Left: The weld line is a T-weld between the rolled or cut edge of the plate and a series of plate surfaces, and the axis of the focused or focused beam is at an angle smaller than θ0 with respect to the series of plate surfaces. Claims 1 to 3 characterized in that they include
The welding method described in any 7 items. The welding method according to claim S, wherein the perpendicularity is S0 to /&'. 7. A welding method according to any one of claims 1 to 1, characterized in that the material blocking the beam is a material that is continuously fed so as to be located approximately at the focal point of the beam. t means for concentrating or focusing a powerful laser beam and means for delivering a beam blocking material to said focal point;
and gas supply means directed towards said focal point for localizing and confining the energy transfer plasma obtained by impinging the focused or focused beam on said beam-obstructing material. A welding head featuring 9. Workstation equipment for use in assemblies by welding metal sheets, such as steel sheets, with at least one such station located at different locations in the flow chain of the workpieces, Each station has a movable laser beam focusing head that can be selectively optically coupled to the optical path of an intense laser beam generator common to the one or more workstations, and at least one of the workstations. A workstation device that is a welding station using a welding procedure. A workstation device according to claim 1, characterized in that a workstation with 5 or less IOs is used as a welding station. II. A generator of a powerful laser beam providing an unfocused coherent beam and one or more angled laser beam mirrors arranged in one or more positions, each of which has seven mirrors. can be selectively interposed in the beam path and have the same number of movable focusing heads, each of which focuses a separate angled laser beam mirror and the beam to a small cross-section. Equipped with a focusing means to Claim 9, characterized in that the beam is deflected to a focusing head mirror comprising an angled mirror selectively interposed in the generated beam and from there to said focusing means. or the workstation device according to any one of Clause 1O. The workstation device according to claim 1, wherein the angled mirror itself is movable in the length direction of the beam. (3)