METHOD FOR THERMALLY CONNECTING TWO WORKPIECE SECTIONS

Abstract

The invention relates to a method for thermally connecting at least two workpiece sections, wherein at least a first and second workpiece section are provided, wherein at least the first workpiece section comprises an edge (1.1, 1.1′, 1.1″, 1.1′″) and the edge (1.1, 1.1′, 1.1″, 1.1′″) defines a termination of an edge section (1.2, 1.2′, 1.2″, 1.2′″), the first and second workpiece sections are positioned relative to one another in such a way that they are connected to one another at least in certain sections in their longitudinal extent, wherein the edge section (1.2, 1.2′, 1.2″, 1.2′″) has a defined geometry. According to the invention, the defined geometry of the edge section (1.2, 1.2′, 1.2″, 1.2′″) is dimensioned in such a way that a local region in the cross section of the edge section (1.2′) is provided with a maximum thickness (t.sub.max1′) at a distance (1.3′) from the edge (1.1′).

Claims

1. A method for thermally connecting at least two workpiece sections, wherein at least a first and a second workpiece section are provided, wherein at least the first workpiece section comprises an edge that defines a termination of an edge section, the first and second workpiece sections are positioned relative to one another in such a way that they are connected to one another at least in certain sections in their longitudinal extent, wherein the edge section has a defined geometry, wherein the defined geometry of the edge section is dimensioned in such a way that a local region in the cross section of the edge section is provided with a maximum thickness at a distance from the edge or at least one section in the transverse extent of the edge section is provided with a maximum thickness proceeding from the edge.

2. The method as claimed in claim 1, wherein a workpiece with a first and a second workpiece section is provided, wherein the second workpiece section comprises an edge and the edge defines a termination of an edge section, and the two edges are connected to one another at least in certain sections in their longitudinal extent in order to generate an at least partially closed profile.

3. The method as claimed in claim 1, wherein a first workpiece with a first workpiece section and a second workpiece with a second workpiece section are provided, and the two workpiece sections are connected to one another at least in certain sections in their longitudinal extent in order to generate a workpiece group.

4. The method as claimed in claim 1, wherein the edges are positioned at a distance from one another in a butt joint.

5. The method as claimed in claim 4, wherein the edges are positioned so as to be in contact with one another at least in certain sections in the butt joint.

6. The method as claimed in claim 5, wherein the edges are positioned with an edge height offset (6) relative to one another in the butt joint.

7. The method as claimed in claim 6, wherein the edge sections (1.2′, 2.2′) are each positioned at an angle (α.sub.1′, 2′) relative to one other.

8. The method as claimed in claim 1, wherein the second workpiece section defines an edge section of the second workpiece, wherein the edge sections are positioned relative to one another in a lap joint.

9. The method as claimed in claim 1, wherein the second workpiece section defines a section of the second workpiece, wherein the edge section of the first workpiece and the section of the second workpiece are positioned relative to one another in a T-joint.

10. The method as claimed in claim 1, wherein the thermal connection is sensor-controlled.

11. The method as claimed in claim 1, wherein the thermal connection is effected by means of arc fusion welding, beam welding, pressure welding, soldering or hybrid methods including combinations thereof.

12. The method as claimed in claim 1, wherein the workpiece used is an uncoated or coated steel material with a tensile strength R.sub.m>600 MPa.

13. A workpiece group produced as claimed in claim 3, wherein the workpiece group is used as part of a chassis or as part of a body of a vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention is explained in more detail below with reference to drawings. Identical parts are always provided with identical reference designations. In detail:

[0039] FIG. 1) shows a schematic partial sectional view of a first exemplary embodiment of a workpiece group,

[0040] FIG. 2) shows a schematic partial sectional view of a second exemplary embodiment of a workpiece group,

[0041] FIG. 3) shows a schematic partial sectional view of a third exemplary embodiment of a workpiece group,

[0042] FIG. 4) shows a schematic partial sectional view of a fourth exemplary embodiment of a workpiece group,

[0043] FIG. 5) shows a schematic partial sectional view of a fifth exemplary embodiment of a workpiece group and

[0044] FIG. 6) shows a schematic partial sectional view of a sixth exemplary embodiment of a workpiece group.

DESCRIPTION OF THE PREFERRED EMBODIMENTS (BEST MODE FOR CARRYING OUT THE INVENTION)

[0045] FIG. 1 illustrates a schematic partial sectional view of a first exemplary embodiment of a workpiece group (10). The workpiece group (10) has been produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1) with a first workpiece section, which comprises an edge (1.1) and the edge (1.1) defines a termination of an edge section (1.2), and a second workpiece (2) with a second workpiece section, which comprises an edge (2.1) and the edge (2.1) defines a termination of an edge section (2.2), have been provided, wherein, in order to generate a workpiece group (10), the two workpiece sections have been connected to one another at least in certain sections in longitudinal extent, preferably completely in longitudinal extent, or are connected to one another via a connection seam (3). The thermal connection can be effected by means of arc fusion welding, beam welding (laser welding), soldering or hybrid methods including combinations thereof, wherein the edges (1.1, 2.1) are positioned at a distance from one another substantially in the butt joint. In this exemplary embodiment, the connection seam (3) was produced by means of laser hybrid welding. The workpieces (1, 2) can consist of the same or different material with the same or different thickness, the thicknesses (t.sub.1,2) of the workpieces (1, 2) being the same in this exemplary embodiment. At least one of the workpieces (1, 2), in particular both workpieces (1, 2), consists/consist of an uncoated or coated steel material with a tensile strength R.sub.m>600 MPa. At least one of the workpieces (1, 2) preferably consists of a dual-phase, complex-phase or Q+P steel material with a tensile strength R.sub.m>700 MPa.

[0046] At least one of the edge sections (1.2, 2.2), in particular both edge sections (1.2, 2.2), has/have a defined geometry which is dimensioned in such a way that at least one section (1.3, 2.3) in the transverse extent of the edge section (1.2, 2.2) is provided with a maximum thickness (t.sub.max1,max2), in particular with a substantially constant maximum thickness (t.sub.max1,max2), proceeding from the edge (1.1, 2.1). The section (1.3, 2.3) or the width thereof is determined, inter alia, in dependence on the HAZ (3.1) and in particular on the region (5) of the metallurgical notch. The geometry of the edge section (1.2, 2.2) differs in particular from the geometry, in particular from the thickness (t.sub.1,2), of the rest of the region of the workpiece (1, 2) and extends in a transverse direction substantially in the region (4) of the geometric notch and in particular in the region (5) of the metallurgical notch or covers said region.

[0047] FIG. 2 illustrates a schematic partial sectional view of a second exemplary embodiment of a workpiece group (10′). The workpiece group (10′) has been produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1′) with a first workpiece section, which comprises an edge (1.1′) and the edge (1.1′) defines a termination of an edge section (1.2′), and a second workpiece (2′) with a second workpiece section, which comprises an edge (2.1′) and the edge (2.1′) defines a termination of an edge section (2.2′), are provided, wherein, in order to generate a workpiece group (10′), the two workpiece sections have been connected to one another at least in certain sections in longitudinal extent, preferably completely in longitudinal extent, or are connected to one another via a connection seam (3′). The thermal connection can be effected by means of arc fusion welding, beam welding, soldering or methods including combinations thereof, wherein the edges (1.1′, 2.1′) are positioned so as to be in contact with one another at least in certain sections substantially in the butt joint, and the edge sections (1.2′, 2.2′) are each positioned at an angle (α.sub.1,2) relative to one another. In this exemplary embodiment, the connection seam (3′) was produced by means of MAG welding. The angle (α.sub.1′,2′) is <180°, in particular <170°, with an angle of for example 150° not being undershot. The workpieces (1′, 2′) can consist of the same or different material with the same or different thickness, the thicknesses (t.sub.1′,2′) of the workpieces (1′, 2′) being the same in this exemplary embodiment. At least one of the workpieces (1′, 2′), in particular both workpieces (1′, 2′), consists/consist of an uncoated or coated steel material with a tensile strength R.sub.m>600 MPa. At least one of the workpieces (1′, 2′) preferably consists of a dual-phase, complex-phase or Q+P steel material with a tensile strength R.sub.m>700 MPa.

[0048] At least one of the edge sections (1.2′, 2.2′), in particular both edge sections (1.2′, 2.2′), has/have a defined geometry which is dimensioned in such a way that a local region in the cross section of the edge section (1.2′, 2.2′) is provided with a maximum thickness (t.sub.max1′,max2′) at a distance (1.3′, 2.3′) from the edge (1.1′, 2.1′). The geometry of the edge section (1.2′, 2.2′) differs in particular from the geometry, in particular from the thickness (t.sub.1′,2′), of the rest of the region of the workpiece (1′, 2′) and extends in the transverse direction substantially in the region (5) of the metallurgical notch or covers said region. The thickness of the workpiece (1′, 2′) increases from the edge (1.1′, 2.1′) as far as the local region (1.3′, 2.3′) with the maximum thickness (t.sub.max1′,max2′). In particular, the increase in thickness takes place within the region (4′) of the geometric notch. Within the edge section (1.2′, 2.2′), the thickness decreases from the local region (1.3′, 2.3′) with the maximum thickness (t.sub.max1′,max2′), and leading away from the edge (1.1′, 2.1′), back to the (initial) thickness (t.sub.1′,2′) of the workpiece (1′, 2′). The thickness thus varies along the cross section in the edge section (1.2′, 2.2′).

[0049] FIG. 3 illustrates a schematic partial sectional view of a third exemplary embodiment of a workpiece group (10″). The workpiece group (10″) has been produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1″) with a first workpiece section, which comprises an edge (1.1″) and the edge (1.1″) defines a termination of an edge section (1.2″), and a second workpiece (2″) with a second workpiece section, which comprises an edge (2.1″) and the edge (2.1″) defines a termination of an edge section (2.2″), are provided, wherein, in order to generate a workpiece group (10″), the two workpiece sections have been connected to one another at least in certain sections in longitudinal extent, preferably completely in longitudinal extent, or are connected to one another via a connection seam (3″). According to the invention, only the edge section (1.2″) of the first workpiece (1″) has been dimensioned in such a way that a section (1.3″) in the transverse extent of the edge section (1.2″) is provided with a maximum thickness (t.sub.max1″) proceeding from the edge (1.1″). The edge section (2.2″) of the second workpiece (2″) has a thickness (t.sub.2″) that is substantially constant with the rest of the region of the workpiece (2″). Furthermore, the region (4″) of the geometric notch and the region (5″) of the metallurgical notch, and also the regions of the HAZ (3.1″), are illustrated. The edges (1.1″, 2.1″) have been positioned with an edge height offset (6) relative to one another, in particular with at least section-wise contact, substantially in the butt joint. This edge height offset (6) has been set on the side facing the side which is thermally loaded in order to generate the connection seam (3″). As a result, in combination with sensor-based seam tracking, the edge joint was detected and a connection was made in the ideal zero gap by means of triangulation. The thermal connection in this exemplary embodiment as well as in the other exemplary embodiments was carried out in a sensor-controlled manner, as a result of which the connection quality was increased owing to the precise orientation/control of the thermal source.

[0050] FIG. 4 illustrates a schematic partial sectional view of a fourth exemplary embodiment of a workpiece group (10′″). The workpiece group (10′″) has been produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1″) with a first workpiece section, which comprises an edge (1.1″) and the edge (1.1″) defines a termination of an edge section (1.2″), and a second workpiece (2″) with an edge (2.1″) and a second workpiece section, which defines an edge section (2.2″), are provided, wherein, in order to generate a workpiece group (10″), the two workpiece sections have been connected to one another at least in certain sections in longitudinal extent, preferably completely in longitudinal extent, or are connected to one another via a connection seam (3′″). The edge sections (1.2″, 2.2″) have been positioned relative to one another in the lap joint. The edge sections (1.2″, 2.2″) are oriented substantially parallel to one another. In this case, only the edge (1.1″) or the associated edge section (1.2″) of the first workpiece (1″) has a geometry which has been changed compared with the rest of the region of the workpiece (1″), wherein a section (1.3″) in the transverse extent of the edge section (1.2″) is provided with a maximum thickness (t.sub.max1″) proceeding from the edge (1.1″). This maximum thickness defines the maximum fillet weld thickness that can be realized. The edge section (2.2″) of the second workpiece (2″) has a thickness (t.sub.2″) that is substantially constant with respect to the rest of the region of the workpiece (2″).

[0051] FIG. 5 illustrates a schematic partial sectional view of a fifth exemplary embodiment of a workpiece group (10′″). In comparison with the fourth exemplary embodiment, a second workpiece (2′″) has been taken into account which, like the first workpiece (1″), has a defined geometry of the edge (2.1′″) or of the edge section (2.2′−), wherein a section (2.3′″) in the transverse extent of the edge section (2.2′″) is provided with a maximum thickness (t.sub.max2′″) proceeding from the edge (2.1′″). The section (1.3″, 2.3′″) or the width thereof is determined, inter alia, in dependence on the HAZ (3.1″″) and in particular on the region (5″″) of the metallurgical notch.

[0052] In addition to arc fusion welding for generating the connection seams (3′″, 3″″) in the fourth and fifth exemplary embodiments, pressure welding, in particular resistance spot welding, can alternatively also be used.

[0053] FIG. 6 illustrates a schematic partial sectional view of a sixth exemplary embodiment of a workpiece group (10′″″). The workpiece group (10′″″) has been produced according to the method according to the invention for thermally connecting at least two workpiece sections. A first workpiece (1′″) with a first workpiece section, which comprises an edge (1.1′″) and the edge (1.1′″) defines a termination of an edge section (1.2′″), and a second workpiece (2″″) with a second workpiece section, which defines a section (2.2″″) as a connecting section, are provided, wherein, in order to generate a workpiece group (10′″″), the two workpiece sections have been connected to one another at least in certain sections in longitudinal extent, preferably completely in longitudinal extent, or are connected to one another via two connection seams (3′″″). The edge section (1.2′″) of the first workpiece (1′″) and the section (2.2″″) of the second workpiece (2″″) have been positioned relative to one another in the T-joint, wherein the edge section (1.2′″) is oriented substantially perpendicular to the section (2.2″″). Only the edge (1.1′″) or the associated edge section (1.2′″) of the first workpiece (1′″) has a geometry which has been changed compared with the rest of the region of the workpiece (1′″), wherein a section (1.3′″) in the transverse extent of the edge section (1.2′″) is provided with a maximum thickness (t.sub.max1′″) proceeding from the edge (1.1′″) The section (2.2″″) of the second workpiece (2″″) has a thickness (t.sub.2″″) that is substantially constant with respect to the rest of the region of the workpiece (2″″). The section (1.3′″) or the width thereof is determined, inter alia, in dependence on the HAZ (3.1′″″) and in particular on the region (5′″″) of the metallurgical notch.

[0054] In principle, it is also possible for a profile/component which is made of a one-piece workpiece and which is closed at least in certain sections in longitudinal extent to be produced, the workpiece sections to be connected of the one workpiece being able to be designed, for example, like those in one of the six exemplary embodiments shown.

[0055] A standard workpiece group was produced from two workpieces made of an uncoated complex-phase steel material of HDT780C grade, each with a thickness t=2 mm, by means of a MAG weld. The two workpieces had a substantially constant thickness also in the edge sections as far as to the edges. The edges were positioned at a distance from one another which was smaller than the thickness of the workpieces, and the edge sections were positioned at an angle of approximately 160° relative to one another and connected to one another completely in longitudinal orientation. Investigations on the workpiece group showed that a region of a geometric notch had formed to the left and right of the edges with approximately +/−2.5 mm, and a region of a metallurgical notch, which substantially reflected and covered the HAZ, had formed to the left and right of the edges with approximately +/−5 mm. The hardness in the cross section of the workpieces was substantially approximately 300 HV 0.5, Vickers hardness determined in accordance with DIN EN ISO 6507-2. In the outer region of the HAZ, said region facing away from the connection seam, the hardness was approximately 250 HV 0.5, which corresponded to a relative drop in hardness of 20%. Analogously to the second exemplary embodiment, two workpieces (1′, 2′) with a defined edge section (1.2′, 2.2′) were connected to one another to form a workpiece group (10′) in the same way as the previously described workpieces. To compensate for the region (5′) of the metallurgical notch, the region in which the minimum hardness was determined in the HAZ of the workpiece group described above was locally reinforced. In order to compensate for the difference in hardness, a maximum thickness (t.sub.max1′,max2′) of 2.4 mm was provided in the edge section (1.2′, 2.2′) at a distance (1.3′, 2.3′) of approximately 4 mm from the edge (1.1′, 2.1′), the relative increase corresponding to 20%. The edge section (1.2′, 2.2′) had a transverse extent of, or the width thereof was, approximately 7.5 mm. The standard workpiece group and the workpiece group (10′) were tested in a force-controlled cyclic vibration test and illustrated in a Wöhler diagram. On the one hand, it could be shown that the failure location for the standard workpiece group was in the region of the HAZ, and for the workpiece group (10′) failure occurred in the (base) material of the one workpiece and not in the connection region. Furthermore, this fracture behavior results in a higher dynamic fatigue strength of the workpiece group (10′).

[0056] The invention is not limited to the embodiments shown, but rather the individual features can be combined with one another as desired. Workpiece groups/component groups of different design can also be presented. By way of example, it is possible for only the edges of a one-piece workpiece to be connected to one another in order to generate a component/profile with closed cross section. The workpiece group (10, 10′, 10″, 10′″, 10″″) is used as part of a chassis or as part of a body of a vehicle. Use in other regions is also conveivable.