DE3304717A1 - METHOD AND DEVICE FOR WELDING PLASTICALLY DEFORMABLE MATERIALS - Google Patents

Abstract

The welding speed of plastically deformable materials when using high power density energy sources, for example a focused laser beam (34) is limited by the formation of defects (cracks, shrinkage cavities, pinholes etc.) in the welding or closed to the latter (butt-joint 11). In order to increase the welding speed while avoiding those defects, the present invention proposes the deformation of the welding (butt-joint welding 11) and the neighbouring areas of the metal sheets (14, respectively 15) so as to press the melted mass formed for the welding and provided by the welding seam, to avoid shrinkage cavities as well as pinholes and to prevent welding strains by plastic deformation in the butt-joint welding area (11). Simultaneously to the deformation of the butt-joint welding (11), it is possible to proceed to its smoothing.

Description

Method and device for welding

plastically deformable materials Description The invention relates to a method for welding plastically deformable materials according to the preamble of claim 1. The invention also relates to a device according to the preamble of claim 12.

Used to weld continuous seams at high speeds a targeted and rapid heating of the joint surfaces of the weld joint is necessary. Energy sources of high power density, namely focused ones, meet these requirements Laser beams or electron beams, ideally. With a laser beam in particular a focused CO2 laser is a power density more than 105W / cm2 achievable. With laser beams all are plastically deformable Materials heatable.

In the known laser fusion welding, which is preferably without Welding consumables are carried out, are seams of perfect quality at welding speeds up to 15 mlmin achievable. Higher welding speeds lead to discontinuities, such as cracks, voids and pores. These discontinuities arise from the unfavorable solidification conditions formed by concentrated laser energy Melt at high speeds. Edge notches and pearl-like cords are formed in the process Weld beads on the surface of the weld seam. These arise among other things. through turbulence in the weld pool, which solidifies quickly. Such welds are due to their bad surface unsuitable for practice. Discontinuities also arise from a steep temperature gradient in the areas of the Sheet metal or sheets. This temperature gradient is due to the rapid warming of the material over the melting range and through rapid, uneven solidification of the weld pool.

After all, this is caused by rapid cooling in the area of the weld seam Shrinkages that lead to significant shrinkage stresses within the same. As a result of these defects, the weld seam is impaired in terms of strength.

The invention is based on the object of a method and a device for welding all plastically deformable materials at high speeds and to create while avoiding the aforementioned discontinuities.

To solve this problem, the method according to the invention has characterizing features of claim 1.

By pressing the welding surfaces together while pressing out the The melt formed on the heated welding surfaces becomes a flawless union the welding surfaces of the weld joint to the weld seam reached.

In the gap formed between the weld surfaces of the weld joint the melt is squeezed by the deformation in such a way that it covers the entire gap fills and, in addition, melt is also pressed out of the gap. qs So there is a flow of the melt in the cleavage plane, mainly in opposite directions, to the edges of the weld seam.

The squeezing or deforming of the sweatband does not take place exclusively in the liquid phase, but also during the transition to the solid phase, when the material has already reached a doughy state.

This effectively counteracts the formation of cavities in the weld seam. Pore formation in the weld seam is also caused by the deformation or pinching prevented.

According to a further proposal of the invention, the deformation is limited not only on the 'melt, but also on those adjacent to the abutment surfaces Edge areas of the sheet metal or sheets deformed. These areas become plastic, thus permanently deformed, the deformation preferably in a transverse to the plane of the gap between the joint surfaces follows. Depending on the weld seam, the direction of deformation can also be inclined to the plane of the gap run with different degrees of deformation over the thickness of the sheet metal.

Since there is mostly permanent deformation in and around the weld seam is carried out, the rapid cooling of the melt and the adjacent Shrinkage stresses occurring in the areas of the butt surfaces are largely compensated or dismantled. The risk of cracking in the weld is reduced in this way counteracted. Depending on the type of weld to be produced, there is a deformation of the sheets by 10% of their thickness possible. The deformation thus exceeds the scope the shrinkage of the sheets as a result of their cooling from the welding temperature to the nominal temperature.

In a particularly advantageous embodiment of the # according to the invention During the process, the sheets or the sheet with the weld joint are continuously focused Laser beam moves past. This creates a continuous, continuous weld seam. As a result, welding speeds are possible with the welding method according to the invention of more than 80 m / min can be achieved. The high efficiency of this welding process allows economical use of the same for seam welding of pipes and Containers or cans for holding liquids or gaseous fillings.

To improve the performance of the welding process according to the invention as well as to improve the weld seam achieved in this way, the abutment surfaces can with Additives are provided. So z. B. a # powder made of the same material be applied lacquer-like to the abutment surfaces to be welded. This serves to increase the absorption of the laser on the Abutment surfaces, where the grain size for the powdery additive preferably over 10 / µm (micrometers) lies. Alternatively, other additives can be used for the targeted alloying of the melt of the sheets to be welded are used, for example Ni powder or Ni foil for welding ferrous materials. An alloy of the melt with such Additive prevents the material from becoming brittle when heated to the melting point and subsequent cooling. Further additives are conceivable for improvement the welding properties of the metal sheets or the sheet metal.

The welding process of the invention can be carried out in a wide variety of gases. In this way, inert gas welding is possible to prevent scaling of the sheets on the to avoid heated edge areas of the abutting surfaces and pollutant diffusions from the atmospheric air into the melt.

Further features of the process relate to the production of an overlap and butt weld. In addition, the method according to the invention can also be used for production other common types of welds are suitable.

The device according to the invention has the characteristic features of claim 12. The pressure organs exert a pressure on the side of the Abutment surfaces bordering area of the metal sheets or of the sheet metal, the arrangement of the pressure elements on the metal sheets, depending on the type of weld is.

According to a further proposal of the invention, the pressure elements are on opposite surfaces of the sheets or

of the sheet metal arranged at a distance from one another which is less than is the thickness of the weld joint or the weld seam. At between the pressure organs As a result of the weld seam being moved through, a continuous deformation of the sheets occurs in the area of the weld joint and the weld seam. The degree of deformation and that The amount of permanent deformation depends on the ratio between the distance the pressure organs among each other and the thickness of the weld joint. To achieve this an optimal weld seam or to adapt to different seam types and To be able to change sheet thicknesses, at least one pressure element can be adjusted in such a way that that the center distances between the opposing pressure elements change.

Depending on the extent of the deformation of the weld seam and the sheets in the area the same can have several groups of opposing pairs of rollers in the longitudinal direction the weld seam be arranged one behind the other. There is a compression of the weld seam thus to be carried out gradually to limit the degree of deformation in the sheets and the weld seam and to reduce the load on the pressure organs.

In addition to a deformation or compression of the weld seam, the Pressure organs are simultaneously made a smoothing of the same, for example through the butt joint covering pressure elements. A smoothing of the weld seam can either directly behind the welding zone by hot deformation or after the The weld seam is carried out at the nominal temperature by cold forming.

In a particularly advantageous embodiment of the invention in a group of opposing pressure elements at least one pressure element at the same time as an drive organ trained. One of the trained as a pressure organ Upsetting rollers acts as a drive roller for this purpose. The drive roller thus combines the Function of a pressure and transport organ. Depending on the driving force required can drive two or more compression rollers opposite one another in a group be, so be designed as drive rollers. Between the opposite Upsetting or drive rollers are the sheets in the area of the weld joint under frictional engagement Entrainment in the longitudinal direction of the weld seam on the focused laser beam or on one Electron beam can be moved past.

Furthermore, the device according to the invention has an adjustable one Welding optics. This is used to focus an incoming laser beam and diverting it specifically into the weld joint. With the one so focused through the welding optics and outward laser beam, the weld joint is targeted and effective to heat the laser beam.

The focused laser beam preferably enters the plane of the weld seam directed into the gap of the weld joint formed between the joint surfaces. Depending on the type of weld to be produced, the laser beam can be perpendicular or parallel to the sheet metal surface or a different inclination to have the same.

Further features of the invention relate to the design of the device to produce an overlap or

Butt weld.

Two exemplary embodiments of the invention are described below with reference to the drawing explained.

Show it: Fig. 1 is a schematic front view a device for welding a lap joint, FIG. 2 is a schematic side view of the device of FIG. 1, and FIG. 3 is a schematic front view of a second Embodiment of a device for welding a butt joint.

The exemplary embodiments show two devices for production continuous weld seams, namely either an overlap seam 10 or a butt seam 11.

The device for forming an overlap seam 10 is shown in FIGS. 1 and 2 shown. With it are two sheets 10 which are flat in the transverse direction to the overlap seam 12 and 13 to be welded. The sheets 12 and 13 are between an upsetting roller 16 and a drive roller 17, which also exerts an upsetting force on the sheets 12, 13, can be moved through. For this purpose, the compression roller 16 and the drive roller 17 are with one another horizontally running, axially parallel axes of rotation in an upright plane opposite.

The compression roller 16 located under the drive roller 17 has in FIG this embodiment has no drive, so it can be freely rotated.

The upsetting roller 16 and the drive roller 17 are spaced apart from one another mounted on a common base plate 24. The distance between a coat 18 of the upsetting roller 16 and a jacket 19 of the drive roller 17 is such selected that this is smaller than the thickness of the 28 in the area of their abutment surfaces or 29 superimposed sheets 12 and 13. In this way occurs between the Coats 18, 19 of the upsetting roller 16 and the drive roller 17 cause deformation of the metal sheets 12, 13 in the area of the overlap seam 10 and the overlap seam 10 itself.

From Fig. 2 is the formation of the lap joint from the metal sheets 12 and 13 can be seen; namely, these are converging from two different planes guided between the oppositely rotating feed roller 17 and compression roller 16. In front of these two rollers 17, 16, the metal sheets 12 and 13 thus converge in a V-shape.

The abutment surfaces 28 and 29 of the sheets 1.2, 13 meet briefly in front of the point at which the jackets 18, 19 of the upsetting roller 16 or the drive roller 17 have the smallest distance from each other.

At the point where the sheets 12, 13 meet, there is a Welding point 20, which is marked schematically in FIG. 2 by a point. Of the Weld point 20 lies approximately in the middle of the weld joint and coincides with the focal point of the focused laser beam 21.

A welding optics arranged at a distance in front of the welding point 20 22 is used to form the focused laser beam 21. In this embodiment a horizontal center line of the welding optics 22 coincides with the one here also horizontally lying plane of the overlap seam 10 together. The welding optics 22 are designed in this way and adjusted so that a laser beam 30 entering the latter perpendicularly is horizontal, d. H. deflected by 900, as a focused laser beam 21 from the welding optics 22 steps out. The focal length of the focal point of the focused one lying at the welding point 20 The laser beam 21 corresponds approximately to the horizontal distance between the welding optics 22 to welding point 20.

The drive roller 17 has in the present embodiment a cylindrical jacket 19. This rests partially on the (upper) plate 12. Stored is the drive roller 17 on one end face by a rigid with a base plate 24 connected support arm 25.

The freely rotatable compression roller 16 resting on the (lower) sheet 13 has a domed skirt 18, i. H.

it is barrel-shaped. The compression roller 16 is supported on their opposite end faces by a U-shaped support arm 27. This is arranged on the base plate 24 so as to be adjustable in height.

This is the distance between the axes of rotation of the drive roller 17 on the one hand and the compression roller 16 on the other hand changeable for enlargement or Reduction of the distance between the jackets 18 and 19 of the same.

This device is used in the area of the abutment surfaces 28 and 29 the height of the sheets 12 and 13 reduced by permanent deformation, so that the The height of the finished lap seam 10 is less than the sum of the original thicknesses the sheets 12, 13 is. The one shown schematically in Fig. 1 - fully blackened - Cross-section of a welding zone 31 runs over the entire width of the abutment surfaces 28 or 29. The welding zone 31 can, however, also be wider if there is melt as a result the deformation has flowed beyond the areas of the abutment surfaces 28, 29.

The device is through the spherical jacket 18 of the upsetting roller 16 this exemplary embodiment also for welding curved metal sheets, in particular for welding the seam of a tube or pipe made of sheet metal.

a can jacket.

Fig. 3 shows a second embodiment of the device for Welding two metal sheets 14 and 15 to form a butt weld 11. With this device a cylindrical drive roller 32 is arranged under the metal sheets 14 and 15. Of the Opposite drive roller 32 are two compression rollers above the metal sheets 14, 15 33 and 34 arranged. Each of the two upsetting rollers 33, 34 is a sheet 14 or 15 assigned, namely the upsetting roller 34 to the sheet 14 and the upsetting roller 33 to the Sheet metal 15. The axes of rotation of the two compression rollers 33, 34 and the drive roller 32 run transversely to the longitudinal direction of the butt seam 11, namely in a common lying vertical plane. With regard to a vertical plane along the butt joint 11, the two upsetting rollers 33 and 34 are arranged symmetrically. The two axes of rotation the upsetting rollers 33 and 34 have the same, oppositely inclined axis of rotation starting from the upright center plane of the device to the metal sheets 14 or 15 is inclined towards. The mutually trimmed end faces of the upsetting rollers 33, 34 thus converge in the direction of the butt joint 11.

The upsetting rollers 33 and 34 are directed away from the butt seam 11 at their ends Front sides each supported on a bearing arm 35 and 36, respectively.

Between the two compression rollers 33 and 34 and the drive roller 32 the two flat sheets .14, 15 are brought together in one plane to form a butt joint with abutment surfaces 37 and 38 extending upright to the plane of the metal sheets 14 and 15. A pressing transversely to the upright abutment surfaces 37 and 38 takes place in this device by the inclined arrangement of the upsetting rollers 33 and 34. In addition, have both compression rollers 33, 34 one at their mutually facing end faces circumferential Bead 39 or 40, each with a semicircular cross-section. The compression rollers 33 and 34 are only with these beads 39, 40 on the upper side of the metal sheets 14, 15 at the edge of the abutment surfaces 37 and 38, respectively. The transverse compressive force on the sheets 14, 15 and the relatively small contact surface of the beads 39 and 40 on the top the same cause deformation in the longitudinal and transverse directions of the abutment surfaces 37 or 38. In this way, particularly on the upper side of the metal sheets 14, 15 next to the weld seam, accumulations of material that have a bead-like shape of the Result in weld seam.

Immediately below the overlap seam 10 is in the cylindrical jacket the drive roller 32 introduced a circumferential annular groove 41, which the drive roller 32 divides into two jacket halves 42 and 43, respectively. This annular groove 41 is used to remove the Flue gas produced when the melt is formed in the weld joint. It is also a Embodiment of the drive roller conceivable in which the annular groove 41 is missing, see above that the jacket of the drive roller also rests on the underside of the butt seam 11, So this smoothes.

In the embodiment of Figure 3, the welding optics 22 is above of the upsetting rollers 33, 34 lying in the upright longitudinal center plane of the butt seam 11 arranged. Here, too, a laser beam 30 enters the welding optics 22 perpendicularly one and occurs in the opposite direction at the bottom of the same than more focused Laser beam 44 from. This accordingly runs upright to the plane of the sheets 14 and 15, is thus directed parallel to the plane of the opposing abutment surfaces 37 and 38, respectively and enters the weld joint approximately in the middle between them. The in The focal point of the focused laser beam 44, not shown in FIG. 3, lies approximately in the middle of the butt joint 11.

Reference numbers 10 overlap seam 11 butt seam 12 block 13 block 14 block 15 block 16 compression roller 17 drive roller 18 jacket 19 jacket 20 spot weld 21 laser beam 22 welding optics 23 24 base plate 25 bearing arm 26 27 support arm 28 abutment surface 29 Joint surface 30 Laser beam 31 Welding zone 32 Drive roller 33 Compression roller 34 Compression roller 35 bearing arm 36 bearing arm 37 abutment surface 38 abutment surface 39 bead 40 bead 41 ring groove 42 shell half 43 shell half 44 laser beam

Claims (27)

Method and device for welding plastically deformable materials Claims method for welding plastically deformable materials, wherein two Joint surfaces to be welded of at least one workpiece (sheet metal) to form a weld joint summarized and by a high power density energy source, in particular at least one focused laser beam, heated to at least melting temperature are used to form a melt that is the (heated) abutment surfaces (28, 29, 37, 38) are pressed together and the melt is deformed is used to unite the abutment surfaces (28, 29, 37, 38) to form a weld seam (lap seam 10, butt weld 11). 2. The method according to claim 1, characterized in that a between'den Joint surfaces (28, 29, 37, 38) gap formed in the weld joint by the melt completely filled and the melt is pressed out of the gap. 3. The method according to claim 1 and 2, characterized in that the Areas of the weld seam adjoining the melt (overlap seam 10, butt seam 11) are compressed with permanent deformation, preferably in a transverse direction to the level of the gap of the weld joint. 4. The method according to claim 3 and one or more of the other Claims, characterized in that the abutment surfaces (28, 29, 37, 38) by approximately 10% of the thickness of the sheet metal or sheets (12, 13, 14, 15) transversely to the plane of the weld joint be compressed. 5. The method according to claim 1 and one or more of the other Claims, characterized in that the melt or the weld seam (lap seam 10, butt weld 11) is deformed p-elastically by compression in such a way that the at When the weld seam cools down, the shrinkage stresses that occur are almost eliminated andfor the weld seam is smoothed. 6. The method according to claim 1 and one or more of the other Claims, characterized in that the sheet or sheets (12..15) with the Weld joint are continuously moved past the laser beam (21, 44) to form a continuous weld seam (lap seam 10, butt seam 11). 7. The method according to claim 1 and one or several of the further claims, characterized in that the abutment surfaces (28, 29, 37, 38) and / or the weld joint formed by the same before or during the heating at least one additive is supplied to the abutment surfaces (28, 29, 37, 38) for improvement the absorption of the light of the laser beam and / or for alloying the liquefied metallic material of the abutment surfaces (28, 29, 37, 38). 8. The method according to claim 1 and one or more of the other Claims, characterized in that the welding is carried out under protective gas is used to prevent scaling on the butt surfaces (28, 29, 37, 38) and Diffusion of elements from the atmospheric air into the metallic materials. 9. The method according to claim 1 and one or more of the other Claims, characterized in that to form a lap joint in two different levels as well as abutting surfaces lying next to one another in the longitudinal direction (28, 29) one or more sheets (12, 13) converging to form the weld joint are brought together to overlap abutment surfaces (28, 29) and the focused Laser beam (21) in the longitudinal direction of the weld joint (lap joint) on the same is straightened with a focal point lying approximately in the middle of the weld joint. 10. The method according to claim 9 and one or more of the further Claims, characterized in that the lap seam (10) is compressed in such a way that that the thickness of the same is less than the sum of the thickness of the two sheets (12, 13) is. 11. The method according to claim 1 and one or more ren of the further claims, characterized in that to form a butt joint the abutting surfaces (37, 38) lying in a plane at a distance from one another or several sheets (14, 15) are brought together and the focused laser beam (44) directed transversely to the plane of the metal sheets (14, 15) or the metal sheet on the butt joint with the focal point in the middle of the weld joint. 12. Device for welding plastically deformable materials with an energy source of high power density, in particular at least one focused Laser beam for heating the joint surfaces that are joined together to form a weld joint at least one workpiece (sheet) at least at melting temperature for formation of melt, characterized in that the sheet or sheets (12..15) through at least two pressure elements (compression roller 16, 33, 34; drive roller 17, 32) can be compressed are under deformation of the melt. 13. The apparatus according to claim 12, characterized in that the Pressure elements (compression roller 16,33,34; drive roller 17, 32) on opposite sides the metal sheets (12..15) or the sheet metal are arranged. 14. Apparatus according to claim 12 or 13, characterized in that that the distance between the opposing pressure elements (compression roller 16, 33, 34; drive roller 17.32) smaller than the thickness of the sheets (12..15) passed between them is. 15. The device according to claim 12 and one or more of the other Claims, characterized in that that the distance between the opposite pressure elements (drive roller or compression roller) is changeable. 16. The device according to claim 20 and one or more of the other Claims, characterized in that welding optics (22) are assigned to the laser is adjustable in such a way that the focal point of the welding optics (22) focused laser beam (21, 44) in the one between the abutting surfaces (28, 29, 37, 38) formed weld joint lies. 17. The device according to claim 12 and one or more of the other Claims, characterized in that the sheet or sheets (12..15) in the longitudinal direction of the weld joint or the weld seam to be produced (overlap seam 10, butt seam 11) can be moved past the focused laser beam (21, 44) by at least one transport element are. 18. The device according to claim 12 and one or more of the other Claims, characterized in that at least one pressure member at the same time as Transport organ serves. 19. The device according to claim 12 and one or more of the other Claims, characterized in that the pressure elements as compression rollers (16,33,34) or the compression rollers serving as a transport element at the same time as a drive roller (17.32) are designed with transverse to the longitudinal direction of the weld seam or the weld joint running axes of rotation for frictional driving of the sheets (12..15) or the Sheet between the drive roller (17, 32) and the opposite upsetting roller (s) (16, 33, 34). 20. The device according to claim 19 and one or more of the other Claims, characterized in that the upsetting rollers (16, 33, 34) have a convex have domed jacket (18,19). 21. The device according to claim .19 and one or more of the other Claims, characterized in that at one. Butt joint joined together, overlapping abutment surfaces (28, 29) a pressure roller (17) and a compression roller (16), preferably axially parallel to each other, opposite each other on a joint surface (28, 29) are arranged adjacent. 22. The device according to claim 21 and one or more of the other Claims, characterized in that the drive roller (17) and the compression roller (16) face each other at a distance slightly smaller than that Thickness of the abutting surfaces (28, 29) lying one above the other. 23. The device according to claim 21 and one or more of the other Claims, characterized in that the compression roller (16) at a distance from the drive roller (17) is adjustable by moving the same transverse to its axis of rotation in the direction to the axis of rotation of the drive roller (17). 24. The device according to claim 19 and one or more of the other. Claims, characterized in that when joined together to form a butt joint Abutment surfaces (37,38) of the sheets (.14,15) or the sheet of a drive roller (17) opposite two compression rollers (16) are assigned, each one (lateral) Touch the edge of the butt joint. 25. The device according to claim 24 and one or more of the further Claims, characterized in that the upsetting rollers (33, 34) are on one side of the metal sheets (14, 15) or the metal sheet to each other with the same, opposite inclination opposite, the inclination of the upsetting rollers (33, 34) is such that of their axes of rotation transverse to the longitudinal direction of the butt joint towards the latter to the sheet metal or sheets (14, 15) run inclined to compress the material in the direction approximately transversely to the plane of the butt joint. 26. The device according to claim 25 and one or more of the further Claims, characterized in that the drive roller (32) has a circumferential annular groove (41) has in its lateral surface, which lies centrally below the butt seam (11) for the removal of vapors or gases formed during welding. 27. The device according to claim 25 and one or more of the further Claims, characterized in that the upsetting rollers (33, 34) have a rotating Bead (39, 40) have semicircular cross-section, which is attached to the metal sheets (14, 15) is present.