DE102017101952A1 - Milling tool for welding electrodes and method to use this - Google Patents

Abstract

A milling tool capable of simultaneously milling and restoring asymmetrical weld side geometries of two welding electrodes subjected to different deterioration mechanisms is disclosed, along with a method of using such a milling tool during resistance spot welding of workpiece stacks containing dissimilar metal workpieces. The milling tool contains a first milling receptacle and a second milling receptacle. The first milling receptacle is defined by one or more first shear surfaces and the second milling receptacle is defined by one or more second shear surfaces. The first shear surfaces and the second shear surfaces are contoured to mill and recover a first weld side geometry and a second weld side geometry, which are different from each other, after recording electrode weld times in the milling fixtures and rotating the milling tool.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of US Provisional Application No. 62 / 291,030, filed Feb. 4, 2016. The disclosure of the above-mentioned provisional application is incorporated herein by reference.

TECHNICAL AREA

The technical field of this disclosure relates generally to a milling tool for reworking welding electrodes used for resistance spot welding of workpiece stacks containing dissimilar workpieces, such as an aluminum workpiece and an adjacent steel workpiece.

BACKGROUND

Resistance spot welding is a process used in a number of industries to join two or more metal workpieces together. The automotive industry, for example, often uses resistance spot welding to join metal workpieces, inter alia, during the manufacture of structural frame members (eg, body side and cross members) and vehicle closure members (eg, vehicle doors, hoods, trunk lids, and tailgates). At various points along one edge of the workpieces of metal or other connection region, a number of welds are often formed to ensure that the part is structurally stable. Although spot welding has typically been practiced to assemble certain similarly assembled metal workpieces - such as steel to steel and aluminum to aluminum - the desire to incorporate lighter materials into a vehicle body structure has been of interest in joining steel workpieces to aluminum workpieces by resistance spot welding generated. The above-mentioned desire for resistance spot welding of dissimilar workpieces made of metal is not unique to the automotive industry; in fact, it extends to other industries that can use spot welding, including the aerospace, marine, railway and construction industries.

Resistance spot welding generally relies on the flow of electrical current through overlapping metal workpieces to generate heat in the intended weld location. To perform such a welding process, a set of opposed welding electrodes are pressed in facing orientation against opposite sides of the workpiece stack, which typically includes two or three metal workpieces arranged in an overlapping configuration. Then, electric current is passed from one welding electrode through the metal workpieces to the other. Resistance to the flow of this electrical current generates heat in the metal workpieces and at their abutment surfaces. When the workpiece stack includes an aluminum workpiece and an adjacent steel overlapping workpiece, the heat generated at the abutting surface and within the material mass of these dissimilar metal workpieces causes the formation of a molten aluminum melt pool which extends from the abutting surface The aluminum workpiece penetrates and allows it to grow. This molten bath of molten aluminum wets the adjacent impact surface of the workpiece made of steel and solidifies after stopping the flow of current to a welded joint, which connects the two workpieces by welding.

Each of the welding electrodes used for performing resistance spot welding includes a welding side disposed at one end of an electrode body. The weld side is the portion of the welding electrode that contacts and electrically communicates the stack of workpieces. Over the course of repeated resistance spot welding operations, the welding sides of the welding electrodes are prone to deterioration due to the large amount of heat generated at the welding sides during current flow and the high compressive force used to press the welding sides against the workpiece stack. This degradation may include plastic deformation of the weld side and / or the occurrence of contamination resulting from a reaction between the electrode and the respective contacted workpiece at elevated temperatures. To extend the life of the welding electrodes, especially in a production environment, the original geometry of the welding sides of the welding electrodes can be periodically restored. This recovery process should be fast, convenient and accurate so that it does not disrupt production operations by leaving the welding electrodes unattainable for extended periods of time.

The resistance spot welding of a workpiece made of aluminum to a workpiece made of steel is subject to problems. Apart from the The need for periodically reworking weld sides that undergo different degradation mechanisms makes the completely different intrinsic switching of the two workpieces and the presence of a mechanically strong, electrically insulating and self healing refractory oxide layer (or layers) on the aluminum workpiece difficult to weld to achieve adequate peel and transverse stress strength in a consistent manner. Since previous efforts in spot welding have not been particularly successful, mainly mechanical fasteners comprising punch rivets and flow-drill screws have been used to fasten aluminum and steel workpieces together. However, mechanical fasteners require more time to install and have high consumption costs compared to spot welding. They also add weight to the vehicle body structure - weight that is avoided when mating is accomplished by means of spot welding - which counteracts some of the weight savings achieved primarily through the use of aluminum workpieces. In addition, mechanical fasteners can introduce sites for galvanic corrosion on the aluminum workpiece, since the fasteners are typically made of steel.

SUMMARY OF THE REVELATION

One embodiment of a milling tool capable of reworking asymmetric weld side geometries of first and second welding electrodes includes a body and a milling element within the body. The body has a first end having a first opening and a second end having a second opening. The milling element has one or more Fräsfurchen. Each of the one or more trench grooves extends inwardly from an interior surface of the body and includes a trimming blade having axially spaced apart and opposite first and second shear surfaces. The one or more milling grooves therefore form a first milling receptacle defined by the first scraping surfaces and accessible through the first opening of the body, and a second milling receptacle defined by the second scraping surfaces and through the second opening of the body is accessible. The first milling receptacle is constructed to mill a first weld side geometry into a weld side of a first weld electrode, and the second mill receptacle is constructed to mill a second weld sidewall geometry into a weld side of a second weld electrode when the weld sides of the first and second weld electrodes in the first and second Fräsaufnahme are received and the milling tool is rotated. The first weld side geometry and the second weld side geometry are different from each other.

The design of the milling tool is subject to a certain variability without losing its ability to rework. For example, each of the one or more milling grooves may comprise an elongate root supporting the cutting blade against the inner surface of the body. The elongate root of each of the one or more trench grooves may be press fit into a retaining channel defined by a lowered surface in the interior surface of the body to rigidly retain the milling element within the body. Or, in another implementation, the elongated foot of each of the one or more milling grooves may be integrally formed with the inner surface of the body to rigidly retain the milling element within the body.

As another example of a specific design of the milling tool, the milling element may include a first milling groove having a first cutting blade, a second milling groove having a second cutting blade, a third milling groove having a third cutting blade, and a fourth milling groove having a fourth milling blade comprising. The first, second, third and fourth cutters are circumferentially spaced from one another such that each of the first, second, third and fourth cutters is oriented transversely of each of its two circumferentially adjacent cutters. In addition, each of the first, second, third and fourth milling blades includes axially spaced and opposite first and second shearing surfaces. The first shearing surfaces of the first, second, third and fourth cutting blades define the first milling receptacle, and the second shearing surfaces of the first, second, third and fourth milling blades define the second milling receptacle.

Further, when the cutting element includes the first, second, third and fourth cutting blades, both the first scraping surface of the first cutting blade and the first scraping surface of the third cutting blade aligned with each other have a lower end portion having an upwardly profiled leading edge and an upwardly profiled trailing edge which is offset by a positive clearance angle below the leading edge. Similarly, both the second shearing surface of the second cutting blade and the second shearing surface of the fourth cutting blade, which are aligned but oriented transverse to the first shearing surface of the first shaving blade and the first shearing surface of the third shaving blade, have a lower end portion following one has a profiled leading edge and an upwardly profiled rear edge, which is offset by a positive clearance angle below the front edge.

The first and second shearing surfaces of the first, second, third and fourth cutting blades may have additional structures adjacent their respective lower end portions. For example, the first shearing surfaces of each of the first, second, third and fourth cutting blades may also include an upper end portion having a convex shape. The upper end portion of the first shearing surface of each of the first, second, third and fourth cutting blades has a leading edge and a trailing edge. Similarly, the second shearing surface of each of the first, second, third and fourth cutting blades may include an upper end portion having a convex shape. The upper end portion of the second shearing surface of each of the first, second, third and fourth cutting blades has a leading edge and a trailing edge.

As yet another example of a particular design of the milling tool, the body of the milling tool may include an annular wall having an outer surface containing an integral retaining nut having a plurality of planar surfaces disposed about the outer surface and abutting cutting circumferentially spaced axial edges. In addition, the body of the milling tool may further include an integral radial flange adjacent and supporting an axial end of the integrated retaining nut to provide a semi-circular bearing surface which projects transversely to each of the planar surfaces of the integral retaining nut. Of course, other constructions and variations of the body of the milling tool may be used to both support the milling element and allow the milling tool to be received and coupled in a rotating milling tool holder.

Another embodiment of a milling tool capable of post-machining asymmetric weld side geometries of first and second welding electrodes includes a body and a milling element within the body. The body extends longitudinally along a central axis between a first end and a second end. The milling element forms a first milling receptacle accessible through the first opening at the first end of the body and further forms a second milling receptacle accessible through a second opening at the second end of the body. The cutting element comprises a milling groove containing a cutting blade having axially spaced apart and opposite first and second shear surfaces which at least partially define the first and second milling receivers, respectively. The first shear surface includes a lower end portion that is contoured to mill a first weld side geometry, and the second shear surface includes a lower end portion that is profiled to mill a second weld side geometry that is different than the first weld side geometry.

The first and second weld side geometries that can be reworked by the milling tool include many different combinations. For example, in one embodiment, the first weld side geometry includes a planar or domed weld side base surface having a diameter between 3 mm and 16 mm, and the second weld side geometry includes a domed weld side base surface having a diameter between 8 mm and 20 mm, and further includes a central plateau centered on the domed weld-side base surface. In another example, the first weld side geometry includes a planar or domed weld side base surface having a diameter between 3 mm and 16 mm, and the second weld side geometry includes a domed weld side base surface having a diameter between 8 mm and 20 mm, and further includes a central plateau centered on the domed weld-side base surface and a plurality of terraces surrounding the central plateau.

In yet another example, the first weld side geometry includes a domed weld side base surface having a diameter between 8 mm and 20 mm and further including a central plateau disposed on the domed weld side base surface and the second weld side geometry includes a domed weld side base surface having a diameter between 8 mm and 20 mm and a series of upstanding circular ridges that project outwardly from the domed weld side base surface. The series of upright circular ridges may contain between two and ten upstanding circular ridges, the diameter of which increases from an innermost upright circular ridge to an outermost upright circular ridge. The upstanding circular ridges may be spaced apart on the arcuate weld-side base surface by a distance of 50 μm to 1800 μm, each of the ridges having a ridge height ranging from 20 μm to 500 μm. And in yet another example, the first weld side geometry includes a domed weld side base surface that has a diameter between 8 mm and 20 mm and further includes a central plateau centered on the domed weld side base surface and the second weld side geometry includes a domed one Weld-side base surface having a diameter between 8 mm and 20 mm and further containing a central plateau centered on the curved weld-side base surface and a plurality of terraces surrounding the central plateau.

The design of the milling tool is subject to a certain variability, without losing its ability to rework. For example, the milling element may comprise a first milling groove having a first milling blade, a second milling groove having a second milling blade, a third milling groove having a third milling blade, and a fourth milling groove having a fourth milling blade. The first, second, third and fourth cutters are circumferentially spaced such that each of the first, second, third and fourth cutters is laterally oriented transversely to each of its two circumferentially adjacent cutters. In addition, each of the first, second, third and fourth milling blades includes axially spaced and opposite first and second shearing surfaces. The first shearing surfaces of the first, second, third and fourth cutting blades define the first milling receptacle, and the second shearing surfaces of the first, second, third and fourth milling blades define the second milling receptacle.

Further, when the cutting element includes the first, second, third and fourth cutting blades, each of the first scraping surface of the first cutting blade and the first scraping surface of the third cutting blade aligned with each other has a lower end portion having an upwardly profiled leading edge and an upwardly profiled trailing edge which is offset by a positive clearance angle below the leading edge. Similarly, both the second shearing surface of the second cutting blade and the second shearing surface of the fourth cutting blade, which are aligned but oriented transverse to the first shearing surface of the first shearing blade and the first shearing surface of the third shaving blade, have a lower end portion which faces one has a profiled leading edge and an upwardly profiled rear edge, which is offset by a positive clearance angle below the front edge.

A method of reworking welding electrodes having asymmetric weld side geometries includes several steps in accordance with an embodiment of the disclosure. In particular, a milling tool is provided which includes a body and a milling element within the body. The milling element comprises one or more milling grooves which form a first milling receptacle and a second milling receptacle. The first milling receptacle is accessible through a first opening at a first end of the body, and the second milling receptacle is accessible through a second opening at a second end of the body. A first welding side of a first welding electrode is received in the first milling receiver, and a second welding side of a second welding electrode is received in the second milling receiver. Once the first and second weld sides are received in the first and second mill receivers, respectively, the mill is rotated to mill and restore a first weld side geometry in the first weld side and a second weld sidewall geometry in the second weld side. The first weld side geometry is different from the second weld side geometry.

The method of reworking welding electrodes having asymmetric weld side geometries may be practiced with particular preference. For example, the milling tool may be rotated between axes of the first and second weld sides at between one and ten complete revolutions, such that a material depth in the range of 10 μm to 500 μm from both the first weld side and the second weld side will restore the first weld side geometry and the second weld side geometry is removed. In addition, a set of ten to one hundred welds may be formed between overlapping and adjacent steel and aluminum workpieces before the first weld side is received in the first mill receptacle of the mill and the second weld side is received in the second mill receptacle of the mill tool. Of course, many other variations of the method of resistance spot welding can be put into practice.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 13 is a perspective view of a milling tool in accordance with an embodiment of the present disclosure, and specifically the first milling receptacle of the milling tool; FIG.

2 is a perspective view of the in 1 illustrated Fräswerkzeugs, and especially the second Fräsaufnahme the milling tool;

3 is an exploded view of the in 1 - 2 shown milling tool, a body and a milling element, which are separated from each other, in Showing conformity with an embodiment of the disclosure;

4 is a cross-sectional view of the in 1 - 2 illustrated milling tool in accordance with an embodiment of the disclosure;

5 is a plan view of the first milling of the in 1 - 2 illustrated milling tool in accordance with an embodiment of the disclosure;

6 is a plan view of the second milling of the in 1 - 2 illustrated milling tool in accordance with an embodiment of the disclosure;

7 FIG. 12 is a cross-sectional view of a blade portion of one of the milling grooves taken along section lines 7-7 in FIG 5 ;

8th FIG. 12 is a cross-sectional view of a blade portion of one of the milling grooves taken along section lines 8-8 in FIG 6 ;

9 FIG. 10 is a general perspective view of a welding electrode including a first welding side geometry in accordance with an embodiment of the disclosure; FIG.

10 FIG. 4 is a general perspective view of a welding electrode including a second welding side geometry different from that in FIG 9 a first weld side geometry shown in accordance with an embodiment of the disclosure;

11 FIG. 10 is a general perspective view of another welding electrode including a first welding side geometry in accordance with an embodiment of the disclosure; FIG.

12 FIG. 12 is a general perspective view of another welding electrode including a second welding side geometry different from the first welding side geometry shown in FIG 11 shown differs in accordance with an embodiment of the disclosure;

13 FIG. 10 is a general perspective view of yet another welding electrode including a first welding side geometry in accordance with an embodiment of the disclosure; FIG.

14 FIG. 4 is a general perspective view of yet another welding electrode including a second welding side geometry different from that in FIG 13 a first weld side geometry shown in accordance with an embodiment of the disclosure;

15 is an enlarged cross-sectional view of the welding side of the in 14 shown welding electrode;

16 FIG. 10 is a general perspective view of yet another welding electrode including a first welding side geometry in accordance with an embodiment of the disclosure; FIG.

17 FIG. 4 is a general perspective view of yet another welding electrode including a second welding side geometry different from that in FIG 16 a first weld side geometry shown in accordance with an embodiment of the disclosure;

18 Figure 11 is a general cross-sectional view of a workpiece stack including a steel workpiece and an adjacent aluminum workpiece overlapped and disposed between a first welding electrode and a second welding electrode, the first and second welding electrodes having different welding side geometries;

19 FIG. 3 is a general cross-sectional view of a workpiece stack including a steel workpiece and an adjacent aluminum workpiece overlapped and disposed between a first welding electrode and a second welding electrode, the first and second welding electrodes having different welding side geometries, although here Workpiece stack includes an additional steel workpiece (ie, two steel workpieces and one aluminum workpiece) in accordance with an embodiment of the disclosure;

20 FIG. 12 is a general cross-sectional view of a workpiece stack including a steel workpiece and an adjacent aluminum workpiece overlapped and disposed between a first welding electrode and a second welding electrode, wherein the first and second welding electrodes have different welding side geometries, although here Workpiece stack contains an additional workpiece made of aluminum (ie, two workpieces made of aluminum and a workpiece made of steel), in accordance with an embodiment of the disclosure;

21 is a general cross-sectional view of the workpiece stack and welding electrodes used in FIG 18 during conduction of electric current between the welding electrodes and through the stack, and wherein the flow of electrical current causes melting of the aluminum workpiece adjacent thereto to the workpiece is made of steel, and has caused the production of a molten pool of molten aluminum within the workpiece made of aluminum;

22 is a general cross-sectional view of the workpiece stack and welding electrodes used in FIG 18 after the flow of electric current between the welding electrodes and through the stack has been completed, and wherein the molten bath of molten aluminum is solidified into a welded joint which adheres the adjacent steel and aluminum workpieces to each other by welding;

23 provides a reworking of at least the welding sides of the first and second welding electrodes, which in 9 - 10 are shown, wherein the first welding electrode ( 9 ) is received in the first milling receptacle of the milling tool and the second welding electrode ( 10 ) is received in the second milling receptacle;

24 provides a reworking of at least the welding sides of the first and second in 11 - 12 shown welding electrodes, wherein the first welding electrode ( 11 ) is received in the first milling receptacle of the milling tool and the second welding electrode ( 12 ) is received in the second milling receptacle; and

25 provides a reworking of at least the welding sides of the first and second in 13 - 14 shown welding electrodes, wherein the first welding electrode ( 13 ) is received in the first milling receptacle of the milling tool and the second welding electrode ( 14 ) is received in the second milling receptacle; and

26 provides a reworking of at least the welding sides of the first and second in 16 - 17 shown welding electrodes, wherein the first welding electrode ( 16 ) is received in the first milling receptacle of the milling tool and the second welding electrode ( 17 ) is received in the second milling receptacle.

PRECISE DESCRIPTION

A milling tool is disclosed that can simultaneously mill and restore asymmetrical weld side geometries of two welding electrodes that are subjected to different degradation mechanisms. The milling tool can be used as part of a method of resistance spot welding a stack of workpieces containing adjacent and overlapping steel and aluminum workpieces. Specifically, a first welding electrode having a first welding side and a second welding electrode having a second welding side may be used to conduct an electric current to a welding machine through the workpiece stack. The geometry of the first weld side and the geometry of the second weld side are asymmetric due to the need to compensate for the different physical properties of the steel and aluminum workpieces. Over time, the first and second weld sides degrade to such an extent that adversely affects spot welding operations. To address this problem, the milling tool may be used to periodically rework both the first and second welding sides of the first and second welding electrodes. Reworking the weld sides involves picking up the first weld side into a first milling receptacle and receiving the second weld side into a second milling receptacle, and then rotating the milling tool about the axes of the first and second weld sides to mill the weld sides and restore their geometries ,

A milling tool and method of using the milling tool in the context of resistance spot welding a workpiece stack that includes adjacent and overlapping steel and aluminum workpieces are described with reference to FIG 1 - 26 described. The milling tool is designed to simultaneously rework the weld sides of both welding electrodes, although the geometries of the weld sides are due to the significant differences in physical properties between the steel and aluminum workpieces (eg, melting point, thermal conductivity, electrical conductivity, elevated temperature strength etc.) are constructed asymmetrically. In this way, the weld sides of both welding electrodes can be periodically reworked with the same milling tool in a single operation to restore their original unique geometries, rather than being reworked separately through their own dedicated milling tools. Reworking the weld sides with the same milling tool is more efficient and can be performed whenever it is desired to counteract weld side degradation mechanisms which, if allowed to proceed without interference, would quickly degrade the quality of the welding electrodes and the spot weld and eventually put them in an inappropriate condition for continued use in spot welding operations. The milling tool can be used to rework the weld sides as much as possible until the weld sides can not support reworking due to the cumulative loss of material due to the reworking operations.

A preferred embodiment of the milling tool is in 1 - 8th shown and by reference numerals 10 designated. The milling tool 10 includes a body 12 and a milling element 14 , The body 12 defines a through hole 16 extending lengthwise along a central axis 18 between a first opening 20 at a first end 22 of the body 12 and a second opening 24 at a second end 26 of the body 12 extends. Each of the openings 20 . 24 is at right angles to the central axis 18 of the through hole 16 so that one level 28 the first opening 20 and a plane 30 the second opening 22 are parallel to each other and from the central axis 18 cut at 90 ° angles, as in 4 is shown. The milling element 14 gets from the body 12 within the through hole 16 held rigidly. The milling element 14 forms a first milling holder 32 and a second milling holder 34 out. The first milling holder 32 is through the first opening 20 of the body 12 accessible through and the second milling receptacle 34 is through the second opening 24 of the body 12 accessible through.

The body 12 and the cutting element 14 are constructed of a hard material capable of withstanding rework operations on welding electrodes. For example, both the body 12 as well as the milling element 14 be formed of a tool steel, such as an S7 or M2 tool steel.

In addition, the milling element 14 from the body 12 be rigidly held in a variety of ways, which prevent these two sections of the tool 10 move relative to each other when the tool 10 is in operation. In one embodiment, the body may 12 and the cutting element 14 discrete single pieces that are assembled and fastened together to the milling tool 10 manufacture. This can be achieved in a number of ways, including mechanical locking, fusion welding, brazing, brazing, adhesive bonding, or a combination of any of these techniques. In another embodiment, the body 12 and the cutting element 14 integrally formed, z. Made of a single solid piece of tool steel to form a single integral piece in the sense that the body 12 and the cutting element 14 previously did not exist as discrete objects.

The body 12 contains a circular wall 36 extending between the axially spaced first and second ends 22 . 26 of the body 12 extends. The circular rim 36 has an inner surface 38 and an outer surface 40 on. The inner surface 38 the annular wall 36 defines the through hole 16 which is through the body 12 including the first and second openings 20 . 24 passes through. The inner surface 38 has a base surface 42 and one or more lowered surfaces 44 on that in the circular wall 36 are lowered in to one or more holding channels 46 to sketch. The one or more retaining channels 46 serve to hold the milling element 14 within the through hole 16 in the event that the body 12 and the cutting element 14 are not formed in one piece. And the holding channels 46 can, like here in 3 is shown, a plurality of axial holding channels 46a included, extending axially from the first end 22 of the body 12 to the second end 26 extend and circumferentially around the inner surface 38 are spaced around, and they may further comprise a circumferential retaining channel 46b included in the circumferential direction around the inner surface 38 extends around and each of the axial retaining channels 46a cuts.

The outer surface 40 the annular wall 36 contains an integrated retaining nut 48 and an integrated radial flange 50 , The integrated. retaining nut 48 stands out of a central part of the annular wall 36 between the first and second ends 22 . 26 of the body 12 and has a variety of flat surfaces 52 on, which are circumferentially spaced from each other axial edges 54 to cut ( 2 ). In a preferred embodiment, the integrated retaining nut 48 six flat surfaces 52 of equal size, hexagonal around the outer surface 40 the annular wall 36 are arranged around. The integrated radial flange 50 Adjacent to an axial end of the integrated retaining nut 48 near either the first or the second end 22 . 26 of the body 12 and supports these. Here is the integrated radial flange 50 in 1 - 9 next to the first end 22 although, if desired, it is just as close to the second end 26 could be arranged. The integrated radial flange 50 extends radially outward over the flat surfaces 52 the integrated retaining nut 48 out to a semi-circular bearing surface 56 to be provided across each of the flat surfaces 52 protrudes, as in 2 and 6 is best shown. The combination of the integrated retaining nut 48 and the integrated radial flange 50 allows the milling tool 10 is received and coupled in a rotatable Fräswerkzeughalterung, such as in a chuck.

The milling element 14 Contains one or more milling grooves 58 which the first and second milling holder 32 . 34 form. The one or more milling grooves 58 are designed to rework welding sides, which are in the first and second milling receptacle 32 . 34 be included, and around to restore asymmetric geometries at these weld sides by a shearing action that results when the milling tool 10 around the central axis 18 of the through hole 16 is turned around. Each of the milling grooves 58 contains a blade 60 on the inside surface 38 the annular wall 36 through an elongated foot piece 62 is supported, which the entire axial dimension of the annular wall 36 spans. As part of the milling element 14 can have one to four milling grooves 58 to be available. In a preferred embodiment, as here in 1 - 6 shown contain the one or more Fräsfurchen 58 a first Fräsfurche 58a , a second milling groove 58b , a third milling groove 58c and a fourth milling groove 58d , The blades 60 and the elongated foot pieces 62 the four milling grooves 58a . 58b . 58c . 58d are in 1 - 6 consequently by reference numerals 60a . 60b . 60c . 60d , respectively. 62a . 62b . 62c . 62d designated.

In the embodiment shown, each of the elongated foot pieces 62a . 62b . 62c . 62d axially in one of the axial retaining channels 46a the inner surface 38 the annular wall 36 introduced and is due to friction due to the exact complementary shape of the retaining channels 46a and the elongated foot pieces 62 firmly held in place, as in 3 is best shown. In addition, the Fräsfurchen 58a . 58b . 58c . 58d Continue to fix in place and in particular an unwanted axial movement of the Fräsfurchen 58a . 58b . 58c . 58d within the through hole 16 To prevent this, a radial spring washer can be used 64 is biased radially outward in the circumferential retaining channel 46b be absorbed and through a transverse groove 66 extend therethrough in a rear end of each of the elongate legs 62a . 62b . 62c . 62d is defined. In addition to or instead of the axially insertable elongate leg pieces 62a . 62b . 62c . 62d and the radial spring washer 64 Other mechanisms can be used to rigidly hold the milling grooves 58a . 58b . 58c . 58d on the inner surface 38 the annular wall 36 within the through hole 16 be used. For safety, in another embodiment, as previously indicated, the elongated foot pieces 62a . 62b . 62c . 62d the milling grooves 58a . 58b . 58c . 58d with the inner surface 38 the annular wall 36 be formed integrally, so that the body 12 and the cutting element 14 to form a single piece of one piece.

The blades 60a . 60b . 60c . 60d the milling grooves 58a . 58b . 58c . 58d stand from the inner surface 38 the annular wall 36 inward and are centrally located within the through hole 16 connected. The blades 60a . 60b . 60c . 60d are circumferentially spaced from each other at regular intervals about the central axis 18 spaced around so that each blade 60 to each of its two circumferentially adjacent blades 60 is oriented across. Each of the blades 60a . 60b . 60c . 60d includes axially spaced and opposite first and second shear surfaces 68 . 70 , Specifically, in this embodiment, the blade contains 60a the first milling groove 58a a first shearing surface 68a next to the first end 22 of the body 12 and a second shearing surface 70a next to the second end 26 of the body 12 , The blades 60b . 60c . 60d the other milling grooves 58b . 58c . 58d contain analogously arranged first and second shear surfaces 68b . 70b . 68c . 70c . 68d . 70d relative to the first and second ends 22 . 26 of the body 12 , Consequently, in this embodiment, those of the milling grooves 58 formed first and second milling recordings 32 . 34 together through the first shearing areas 68a . 68b . 68c . 68d or the second shearing surfaces 70a . 70b . 70c . 70d Are defined.

The first shearing surfaces 68a . 68b . 68c . 68d are profiled to mill and restore an electrode weld side of a first geometry, and the second shear surfaces 70a . 70b . 70c . 70d are profiled to mill and restore an electrode weld side of a second geometry that differs from the first geometry. The different profiles of the first shearing surfaces 68a . 68b . 68c . 68d and the second shearing surfaces 70a . 70b . 70c . 70d allow that the milling tool 10 restores the first weld side geometry to a welding electrode that is in the first milling receptacle 32 was recorded, and at the same time, that the second weld side geometry for another welding electrode, which in the second milling 34 was recorded, restores while the tool 10 around the central axis 18 of the through hole 16 is turned around. This is the milling tool 10 be able to rework two welding electrodes with asymmetrical weld side geometries, which is a useful reworking practice when performing resistance spot welding with significantly different welding electrodes, such as when the workpiece stack being welded includes an aluminum workpiece and an adjacent steel workpiece.

The first and second weld side geometries from the first shear surfaces 68 or the second shear surfaces 70 are designed for resistance spot welding of a workpiece stack containing adjacent and overlapping steel and aluminum workpieces. The design of the weld side geometries is based to a large extent on the different material physical properties of the workpiece made of steel and the workpiece made of aluminum, which are spot welded together. Specifically, the first weld side geometry used on the steel side welding electrode is designed to concentrate a flow within the steel workpiece (relative to the aluminum workpiece) and also to cause a certain deformation of the steel workpiece during electrical current flow. This advantageously utilizes the low conductivity - both thermal and electrical - of the steel workpiece and its increased melting point relative to the aluminum workpiece. In a somewhat different manner, the second weld side geometry used on the aluminum side electrode is designed to break up the refractory oxide layers on the aluminum workpiece and to contain the molten bath of molten aluminum that grows within the aluminum workpiece. Both the size and shape of the second weld side geometry have an effect on the content of the molten bath of molten aluminum as it grows.

With reference now to 1 . 5 and 7 contains at least one of the first shearing surfaces 68a . 68b . 68c . 68d a lower end portion 72 and an upper end portion 74 , The lower end section 72 extends at least to the central axis 18 of the through hole 16 and points. a leading edge 76 and a trailing edge 78 on. The leading edge 76 is from a distal tip 80 is profiled from the top and is contoured to mill at least the first weld side geometry and any surrounding transitional approach in a welding electrode. After restoration, the first geometry weld site has a specified diameter and, in addition, a specified planar or domed shape that may include additional protruding or engaging surface features. The trailing edge 78 of the lower end portion 72 is like the leading edge 76 profiled upwards, but under the front edge 76 offset so that the shear surface 68 within the lower end section 72 from the front edge 76 to the trailing edge 78 is inclined at a positive clearance angle, which is in a range of 3 ° to 8 °. The positive clearance angle is in 7 generally shown.

The upper end section 74 the first shearing surface 68 has a convex shape and extends from the lower end portion 72 to the elongated foot piece 62 the milling groove 58 , The upper end section 74 has a leading edge 82 and a trailing edge 84 on. These two edges 82 . 84 can have a positive clearance angle like the lower end section 72 but it does not necessarily have to be offset because the upper end section 74 not necessarily involved in the milling of the first weld side geometry. Instead, the upper end section is used 74 during a rotation of the milling tool 10 around the axis 18 of the through hole 16 around for centering and guiding the welding electrode down to the lower end portion 72 out. When a welding electrode in the first milling receptacle 32 is recorded and the milling tool 10 is rotated to restore the first Schweißseitengeometrie, comes the upper end portion 74 the shearing surface 68 Indeed, typically not in contact with the neighboring regions of the welding electrode, which are located outside the welding side and the transition approach, and therefore not milled them.

Included here in the embodiment of 1 . 5 and 7 two of the aligned first shear surfaces 68a . 68c the lower end portion just described 72 while the other two aligned first shear surfaces 68b . 68d a variation of the lower end portion 72 in which the only significant difference is that the distal tip 80 not all the way to the middle axis 18 of the through hole 16 extends. Each of the four shearing surfaces 68a . 68b . 68c . 68d also includes the upper end portion described above 74 for guiding and centering the welding electrode. All four first shearing surfaces 68a . 68b . 68c . 68d In this embodiment, therefore, they are profiled to participate in the milling of a weld side to restore the first geometry, while also helping to align the welding side of the welding electrode and placing it in the correct position within the first milling receptacle 32 respectively. In this embodiment, the four shear surfaces 68a . 68b . 68c . 68d used together to make restoring the first geometry easier and less time-consuming.

With reference now to 2 . 6 and 8th contains at least one of the second shearing surfaces 70 a lower end portion 86 and an upper end portion 88 similar to the first shearing surfaces 68 , The lower end section 86 extends at least to the central axis of the through hole 16 and has a leading edge 90 and a trailing edge 92 on. The leading edge 90 is from a distal tip 94 from upwardly profiled and contoured to mill at least the second weld side geometry and any surrounding transition lug into a welding electrode. After restoration, the second geometry weld site has a specified diameter and, in addition, a specified domed shape that may include additional protruding or engaging surface features. The trailing edge 92 of the lower end portion 86 is like the leading edge 90 profiled upwards, but is under the leading edge 90 offset so that the shearing surface 70 within the lower end section 86 from the front edge 90 to the trailing edge 92 inclined at a positive clearance angle ranging from 3 ° to 8 °. The positive clearance angle is in 8th shown.

The upper end section 88 the second shearing surface 70 has a convex shape and extends from the lower end portion 86 up to the elongated foot piece 62 the milling groove 58 , The upper end section 88 has a leading edge 98 and a trailing edge 100 on. These two edges 98 . 100 can by a positive clearance angle as in the lower end portion 86 be offset, but this is not necessarily because the upper end section 88 not necessarily involved in milling the second weld side geometry. Instead, the upper end section is used 88 as before during a rotation of the milling tool 10 around the central axis 18 of the through hole 16 around for centering and guiding the welding electrode down to the lower end portion 86 out. If a welding electrode in the second milling receptacle 34 is recorded and the milling tool 10 is rotated to restore the second Schweißseitengeometrie, comes the upper end portion 88 the second shearing surface 70 In fact, typically not in contact with the adjacent regions of the welding electrode, which are outside the welding side and the transition lug, and therefore does not milled them.

In the embodiment of 2 . 6 and 8th comprise two of the aligned second shear surfaces 70b . 70d the lower end portion just described 86 while the other two aligned second shear surfaces 70a . 70c a variation of the lower end portion 86 in which the only significant difference is that the distal tip 94 not over the entire distance to the central axis 18 of the through hole 16 extends. Each of the second shearing surfaces 70a . 70b . 70c . 70d also contains the upper end section 88 as described above for guiding and centering the electrode. All four second shearing surfaces 70a . 70b . 70c . 70d are therefore profiled in this embodiment to participate in the milling of a weld side to restore the second geometry while also aligning and guiding the weld side of the weld electrode to the correct position within the second mill receptacle 34 support. In this embodiment, the four shear surfaces 70a . 70b . 70c . 70d used together to make restoring the first geometry easier and less time-consuming. In addition, as shown, the second shear surfaces 70b . 70d , the distal tips 94 which extend to the central axis 18 of the through hole 16 extend, not on the same blades 60 present like the first shearing surfaces 68a . 68c analogous to distal tips 80 have up to the central axis 18 of the through hole 16 extend. The two sets of first and second shear surfaces 68a . 68c . 70b . 70d instead are at the cutting element 14 oriented transversely to each other.

It will be appreciated that other mill ridge constructions designed to rework the asymmetric first and second weld side geometries are, of course, possible and as an alternative to the mill ruts 58a . 58b . 58c . 58d - with their opposite first and second shear surfaces 68a . 68b . 68c . 68d . 70a . 70b . 70c . 70d - which are shown in the figures and described above, can be used. The milling element 14 For example, only one Fräsfurche 58 with a first shearing surface 68 and a second shearing surface 70 contain. The axially spaced apart first and second shear surfaces 68 . 70 may be the lower end portions described above 72 . 86 contain. In another example, the milling element 14 two opposite milling grooves 58 each of which contains a first scraping surface 68 and a second shearing surface 70 having. The first shearing surfaces 68 and the second shearing surfaces 70 the opposite Fräsfurchen 58 can be constructed in the same way as the surfaces described above 68a . 68c or surfaces 70b . 70d ,

The first and second weld side geometries created by the first and second milling fixtures, respectively 32 . 34 can be milled and restored, can take a variety of configurations. Some of the specific combinations of first and second weld side geometries are in 9 - 14 shown. In these examples, the first and second weld side geometries are designed for resistance spot welding of workpiece stacks containing adjacent overlapping steel and aluminum workpieces. The very different weld side geometries are used to address and address the unique problems created by the dissimilar steel and aluminum workpieces in resistance spot welding, and ultimately to make it easier to consistently achieve weld bonds with good strength properties. Although the special weld side geometries used in 9 - 14 Although illustrated and described in the following text are useful in combination with each other, it should be understood that other weld side geometries may be adjusted to achieve similar goals, although not explicitly shown and described herein.

A special combination of weld side geometries is in 9 - 10 shown. Here is a welding electrode 200 (which also as the " first welding electrode 200 "), Which contains the first weld side geometry and through the first shear surfaces 68 the one or more Fräsfurchen 58 can be reworked in 9 shown, and a welding electrode 220 (also called the "second welding electrode 220 Contains second weld side geometry and through second shear surfaces 70 the one or more Fräsfurchen 58 can be reworked is in 10 shown. The first and second welding electrodes 200 . 220 can be made of any electrically and thermally conductive material that is suitable for spot welding applications and that may deteriorate during welding. The welding electrodes 200 . 220 may for example consist of a copper alloy having an electrical conductivity of at least 80% IACS or more preferably of at least 90% IACS and a thermal conductivity of at least 300 W / mK or more preferably of at least 350 W / mK. A specific example of a copper alloy that may be used is a copper-zirconium alloy (CuZr alloy) containing about 0.10 to about 0.20% by weight zirconium and otherwise copper. Copper alloys that meet this ingredient composition and are referred to as C15000 are preferred. Other suitable materials that make up the welding electrodes 200 . 220 may comprise a copper-chromium alloy (CuCr alloy) C18200, a copper-chromium-zirconium alloy (CuCrZr alloy) C18150 or a heat-resistant metal composite such as a tungsten-copper composite.

The first welding electrode 200 contains an electrode body 202 and a welding side 204 , The electrode body 202 preferably has a cylindrical shape and includes a front end 206 with a scope 2060 , A diameter 2062 of the body 202 at its front end circumference 2060 is preferably in the range of 12 mm to 22 mm or narrower in the range of 16 mm to 20 mm. The welding side 204 is at the front end 206 of the body 202 arranged and has a scope 2040 on, with the scope 2060 of the front end 206 of the body 202 coincides (a "full page electrode") or by a transient approach 208 with a frusto-conical or cut spherical shape to the circumference 2060 of the front end 206 is shifted upwards by a distance between 2 mm and 10 mm. If the transitional approach 208 is frusto-conical, the truncation angle is preferably between 15 ° and 40 ° from a horizontal plane of the weld side perimeter 2040 out. If the transitional approach 208 is spherical, the radius of curvature of the transitional approach is 208 preferably between 6 mm and 20 mm or narrower between 8 mm and 12 mm.

The welding side 204 preferably has one at its periphery 2040 measured diameter 2042 which is in the range of 3 mm to 16 mm or narrower in the range of 4 mm to 8 mm. With regard to its shape, the welding side contains 204 a weld-side base surface 210 that can be level or curved. When the welding side base surface 210 arched, it rises from the perimeter 2040 the welding side 204 upward and inward to achieve an upwardly curved convex shape. For example, the weld-side base surface 210 in a particular embodiment, be spherically curved to have a spherical profile with a radius of curvature that is preferably in the range of 8 mm to 400 mm or narrower in the range of 25 mm to 100 mm. The geometry of the welding side 204 - regardless of whether they have a flat or curved shape with their prescribed diameter 2042 - can be milled and restored by the deteriorated welding side 204 in the first milling holder 32 of the milling tool 10 is recorded and then the tool 10 around an axis 212 the welding side 204 is turned around. In this way, the first shearing surfaces shear 68 the one or more Fräsfurchen 58 Welding side material to expose new Schweißseitenmaterial and restore the first Schweißseitengeometrie.

The second electrode 220 contains an electrode body 222 and a welding side 224 , The electrode body 222 preferably has a cylindrical shape and includes a front end 226 with a scope 2260 , A diameter 2262 of the body 222 the one at its periphery 2260 is measured in the front end, is preferably in the range of 12 mm to 22 mm or narrower in the range of 16 mm to 20 mm. The welding side 224 is at the front end 226 of the body 222 arranged and has a scope 2240 on, with the scope 2260 of the front end 226 of the body 222 matches (a "full page electrode") or the circumference 2260 of the front end 226 through a transitional approach 228 with a frusto-conical or cut spherical shape offset by a distance between 2 mm and 10 mm upwards. If the transitional approach 228 is frusto-conical, the truncation angle is preferably between 30 ° and 60 ° from a horizontal plane of the weld side perimeter 2040 out. If the transitional approach 228 is spherical, the radius of curvature of the transitional approach is 228 preferably between 6 mm and 12 mm.

The welding side 224 preferably has a diameter 2242 on, at its periphery 2240 is measured and in the range of 8 mm to 20 mm or narrower in the range of 10 mm to 15 mm. With regard to its shape, the welding side contains 224 a weld-side base surface 230 and a central plateau 232 , The welding side base surface 230 is curved and therefore rises from the perimeter 2240 the welding side 224 from upwards and inwards to reach an upwardly curved convex shape. For example, in one particular embodiment, the weld-side base surface may be 230 be spherically curved in that it has a spherical profile with a radius of curvature which is preferably in the range of 15 mm to 300 mm or narrower in the range of 20 mm to 50 mm. The central plateau 232 is on the weld-side base surface 230 around an axis 234 the welding side 224 centered around it and it is surrounded by a circular section of the weld-side base surface 230 surround. The central plateau 232 is a surface feature that allows the second welding electrode 220 can be used in conjunction with many types of workpiece stacks in resistance spot welding operations, as in U.S. Patent No. 8,525,066 is described. In addition to the central plateau 232 can the welding side 224 if desired, upright circular ridges or circular penetration grooves (relative to the weld side base surface) 230 ) containing the central plateau 232 surround.

The central plateau 232 contains a plateau surface 236 and a side surface 238 , The plateau surface 236 is 0.1 mm to 0.5 mm above the surrounding weld-side base surface 230 moved constructively and is shallower than the welding side base surface 230 , The plateau surface 236 For example, it may be flat or may have a spherical radius of curvature greater than the spherical radius of curvature of the weld-side base surface 230 is. When the plateau surface 236 is spherically shaped, the radius of curvature of the plateau surface 236 preferably 40 mm or larger. In addition, the plateau surface 236 in plan view (ie, view from top to bottom) be circular and the side surface 238 showing the plateau surface 236 constructively over the weld side base surface 230 shifts, may have a cylindrical shape. When the plateau surface 236 is circular in plan view, it may have a diameter which is in the range of 3 mm to 7 mm.

The second geometry of the welding side 224 In particular, the domed weld side base surface 230 with the upright central plateau 232 and the prescribed diameter 2242 the welding side 224 - Can by picking up the deteriorated welding side 224 in the second milling holder 34 of the milling tool 10 and then by turning the tool 10 around the axis 234 the welding side 224 milled and restored around. In this way, the central plateau 232 the welding side 224 engaged in a corresponding engagement extending at least over part of the distance from the leading edge 90 up to the trailing edge 92 of the lower end portion 86 the second shearing surfaces 70 the one or more Fräsfurchen 58 extends, and the rotation of the milling tool 10 shears off weld side material to expose new weld side material and restore the second weld side geometry. The first and second weld side geometries of the first and second welding electrodes 200 . 220 can be done by turning the milling tool 10 be restored at the same time while both the first welding side 204 as well as the second welding side 224 in the first or second milling holder 32 . 34 are included.

Another special combination of weld side geometries is in 11 - 12 shown. There is in 11 a welding electrode 300 (also called the "first welding electrode 300 "), Which contains the first weld side geometry and through the first shear surfaces 68 the one or more milling grooves 58 can be reworked, and a welding electrode 320 (also called the "second welding electrode 320 "), Which contains the second weld side geometry and through the second shear surfaces 70 the one or more milling grooves 58 can be reworked is in 12 shown. The first and second welding electrodes 300 . 320 can be made of any electrically and thermally conductive material that is suitable for spot welding applications and may experience degradation in welding. For example, the welding electrodes 300 . 320 as before, consist of a copper alloy which has an electrical conductivity of at least 80% IACS or more preferably at least 90% IACS and a thermal conductivity of at least 300 W / mK or more preferably at least 350 W / mK, and of other electrically and thermally conductive Materials.

The first welding electrode 300 is equal to the first welding electrode 200 , in the 9 is shown. In particular, the first welding electrode contains 300 a body 302 and a welding side 304 structurally equal to the body 202 and the welding side 204 the first welding electrode described above 200 are. Therefore, corresponding reference numerals in FIG 11 used to structural aspects of the first welding electrode 300 to describe the same as those of the first welding electrode described above 200 and further the above disclosure with respect to these Include structure attributes. Due to the structural similarity between the two electrodes 200 . 300 does not become a redundant description of the first welding electrode 300 from 11 needed. The difference of the weld side geometry combination of 11 - 12 in comparison with 9 - 10 based solely on the second welding electrode 320 , in the 12 is shown.

The second welding electrode 320 resembles the second welding electrode 220 , in the 10 is shown, in many aspects. Here contains the second welding electrode 320 as shown a body 322 and a welding side 324 which are structurally equal to the body 222 and the welding side 224 the second welding electrode described above 220 are - and therefore designated by corresponding reference numerals - with the exception that the welding side 324 In addition, a variety of terraces 340 which contains a central plateau 332 surround. The variety of terraces 340 can be from two to ten terraces 340 each comprising an upper terrace surface 342 and a side surface 344 Contains by a rounded circumferential shoulder surface 346 are connected. The upper terrace surface 342 every terrace 340 is axially below the upper terrace surface 342 their radially inward adjacent terrace 340 moved, or in the case of the terrace 340 that the central plateau 332 immediately surrounds, under a plateau surface 336 , The upper terrace surface 342 every terrace 340 may be planar or spherical with a radius of curvature ranging from 100 to 400 mm, and the shoulder surfaces 346 the multitude of terraces 340 are preferably separated by a radial distance which is in a range of 200 μm to 1500 μm.

From a side surface 338 of the central plateau 332 Starting from there, depends the multitude of terraces 340 to each other; that is, the upper terrace surface 342 every terrace 340 the side surface 344 their radially inward adjacent terrace 340 (or the page surface 338 of the central plateau 332 in the case of the innermost terrace 340 ) and extends radially outward from it. In fact, in the embodiment shown here, the welding side contains 324 the second welding electrode 320 three terraces 340 , A first terrace 340a hangs with the central plateau 332 together and contains an upper terrace surface 342a extending from the side surface 338 of the central plateau 332 out to their own page surface 344a extends. A second terrace 340b hangs with the first terrace 340a together and contains an upper terrace surface 342b extending from the side surface 344a the first terrace 340a out to their own page surface 344b extends. And in a similar way hangs a third terrace 340c with the second terrace 340b together and contains an upper terrace surface 342c extending from the side surface 344b the second terrace 340b out to their own page surface 344c extends. Any additional terraces 340 that are radially outside the third terrace 344c may be present in the same way with the rest of the terraces 340 together.

The first and second geometries of the welding pages 304 . 324 can be milled and restored by the deteriorated welding side 304 . 324 in the first or second milling holder 32 . 34 of the milling tool 10 be included and then the tool 10 around the axes 312 . 334 the welding pages 304 . 324 is rotated around as above with reference to 9 - 10 is described. The main difference here is that the second welding side 324 now in addition to the central plateau 332 a variety of terraces 340 contains. In this regard, the second shear surfaces included 70 the one or more Fräsfurchen 58 now several interventions, covering at least part of the distance from the leading edge 90 to the trailing edge 92 of the lower end portion 86 extend. The central plateau 332 and the multitude of terraces 340 are locked within these respective interventions so that during a rotation of the milling tool 10 the second shearing surfaces 70 Shear off the weld side material to expose new weld side material and restore the second weld side geometry.

Another special combination of weld side geometries is in 13 - 14 shown. There is in 13 a welding electrode 420 (also referred to as the "first welding electrode 420 "), Which contains the first weld side geometry and through the first shear surfaces 68 the one or more Fräsfurchen 58 can be reworked, and a welding electrode 520 (also called the "second welding electrode 520 "), Which contains the second weld side geometry and through the second shear surfaces 70 the one or more Fräsfurchen 58 can be reworked is in 14 shown. The first and second welding electrodes 420 . 520 can be made of any electrically and thermally conductive material that is suitable for spot welding applications and may deteriorate during welding. For example, the welding electrode 420 . 520 as before consist of a copper alloy having an electrical conductivity of at least 80% IACS or more preferably at least 90% IACS and a thermal conductivity of at least 300 W / mK or more preferably at least 350 W / mK and other electrically and thermally conductive materials.

The first welding electrode 420 is equal to the second welding electrode 220 , in the 10 is shown. In particular, the first welding electrode contains 420 a body 422 and a welding side 424 structurally equal to the body 222 and the welding side 224 the second welding electrode described above 220 are. In 13 Accordingly, corresponding reference numerals are used to structural aspects of the first welding electrode 420 to denote those equal to those of the second welding electrode described above 220 and further to incorporate the above disclosure regarding these similar structural attributes. Because of the structural similarity between the two electrodes 420 . 220 Here is a redundant description of the first welding electrode 420 from 13 not required. Like the first welding electrode 420 also contains the second welding electrode 520 at least one weld side surface feature.

The second electrode 520 is similar in many ways to the one in 10 shown second welding electrode 220 , Here contains the second welding electrode 520 as shown a body 522 and a welding side 524 structurally equal to the second welding electrode described above 220 are - and therefore described with corresponding reference numerals - with the exception that the welding side 524 does not contain a central plateau, but instead a series of upright circular ridges 550 , These upright, circular ridges 550 stand from a weld-side base surface 530 out to the outside and allow the second welding electrode 520 makes good mechanical and electrical contact with the surface of an aluminum workpiece by stressing and piercing the mechanically strong and electrically insulating refractory oxide layers which typically coat the surface of an aluminum workpiece.

The row of upright, circular ridges 550 is preferably about an axis 534 the welding side 524 centers around and surrounds them. The welding side base surface 530 from which the burrs 550 can protrude 50% or more, and preferably between 50% and 80% of the surface of the welding side 524 occupy. The remaining surface is the series of upright circular ridges 550 assigned, which preferably from two to ten burrs 550 or narrower from three to five burrs 550 includes. The several upright circular ridges 550 are on the weld-side base surface 530 spaced radially from each other such that the upstanding ridges 550 have a larger diameter when moving from the innermost, upright ridge 550a ( 15 ), which is the axis 534 the welding side 524 immediately surrounds, to the outermost upright ridge 550b ( 15 ), which is the scope 5240 the welding side 524 is closest and therefore off the axis 534 the welding side 524 farthest away.

The size and shape of the upright, circular ridges 550 are subject to a certain variability without losing their ability to rework. In one embodiment, the best in 14 1, each of the upstanding circular ridges faces 550 a closed perimeter, which means that the circumference of the ridge 550 is continuously curved and therefore is not interrupted by significant separation points, and is additionally defined by a cross-sectional profile having no sharp corners while having a curved or flat upper surface (as shown). In addition, each of the circular ridges points 550 , as in 15 shown is also a ridge height 550h on - at the midpoint of the ridge 550 measured - which differs from the weld-side base surface 530 when viewed in cross section extends upward. The ridge height 550h every ridge 550 is preferably in a range of 20 microns to 500 microns or narrower from 30 microns to 300 microns. And the space between the ridges 550 that is between the centers of two adjacent ridges 550 is measured, is preferably in a range of 50 microns to 1800 microns or narrower from 80 microns to 1500 microns. Each of the circular ridges 550 is preferably semi-circular in cross-section, truncated semi-circular or triangular.

The first and second geometries of the welding pages 424 . 524 can be milled and restored by the deteriorated weld sides 424 . 524 in the first or second milling holder 32 . 34 of the milling tool 10 be included and then the tool 10 around the axes 434 . 534 the welding pages 424 . 524 is turned around. More specifically, the first welding side 424 through the first shearing surfaces 68 the one or more Fräsfurchen 58 milled. In this way and very much like in 10 is the central plateau 432 the first welding side 424 engaged in a corresponding engagement extending at least over part of the distance from the leading edge 76 to the trailing edge 78 of the lower end portion 72 the first shearing surfaces 68 the one or more Fräsfurchen 58 extends, and the rotation of the milling tool 10 shears off weld side material to expose new weld side material and to restore the first weld side geometry.

The second side of welding 524 is through the second shear surfaces 70 [English: cutting surfaces] of the one or more milling grooves 58 milled. This defines the second shearing surface 70 the one or more Fräsfurchen 58 a variety of penetration grooves extending from the leading edge 90 from at least part of the way to the trailing edge 92 in the lower end portion 86 extend. The penetration grooves, over the second shear surfaces 70 can be straight or curved, preferably comprise between two and ten grooves extending over the entire length of the shear surfaces 70 from the front edge 90 up to the trailing edge 92 extend. Each of the penetration grooves has a height (measured as the maximum penetration distance from the shear surface 70 at the front edge 90 from) ranging from 20 μm to 500 μm or narrower from 50 μm to 300 μm. The penetration grooves are also along the shear surface 70 spaced apart (measured as the distance between the centers of adjacent grooves along the shear surface 70 at the front edge 90 ), wherein the distance is in a range of 50 microns to 1800 microns or narrower from 80 microns to 1500 microns. In a preferred embodiment, the underside of each of the penetrating grooves has a constant radius of curvature to produce a blunt or rounded shape in cross-section, although of course other alternative cross-sectional shapes are possible, including truncated semicircular and triangular shapes.

The penetration grooves may be different from the leading edge 90 over the second shearing surfaces 70 extend at a positive clearance angle equal to the clearance angle of the shearing surface 70 is or differs from it. In particular, the positive clearance angle of the penetration grooves from the leading edge 90 to the trailing edge 92 in a range of 1.5 ° to 20 ° or narrower from 5 ° to 15 °. When the penetration grooves just over the second shearing surface 70 extend, is the clearance angle of the grooves 96 preferably greater than 8 ° to allow sufficient clearance between the groove inner walls and the upstanding ridges, during rotation of the milling tool 10 milled and restored. However, if the penetration grooves over the second shearing surface 70 In order to conform to the curvature of the ridges that are milled and restored, the positive clearance angle may be equal to or even less (eg, down to 1.5 °) than the clearance angle of the second shear surface 70 because the curvature of the grooves naturally limits interference between the groove inner walls and the ridges that are milled and restored. A discussion of an embodiment of penetration grooves extending into the second shear surfaces 70 can be included in US application number 15 / 418,768, the entire disclosure of which is incorporated herein by reference.

Yet another special combination of weld side geometries is in 16 - 17 shown. There is in 16 a welding electrode 620 (also referred to as the "first welding electrode 620 "), Which contains the first weld side geometry and through the first shear surfaces 68 the one or more Fräsfurchen 58 can be reworked, and a welding electrode 720 (also called the "second welding electrode 720 "), Which contains the second weld side geometry, and through the second shear surfaces 70 the one or more Fräsfurchen 58 can be reworked is in 17 shown. The first and second welding electrodes 620 . 720 may be made of any electrically and thermally conductive material that is suitable for spot welding applications and may experience degradation during welding. For example, the welding electrodes 620 . 720 as before, consist of a copper alloy having an electrical conductivity of at least 80% IACS or more preferably at least 90% IACS and a thermal conductivity of at least 300 W / mK or more preferably at least 350 W / mK, as well as other electrically and thermally conductive Materials.

The first welding electrode 620 is equal to the second welding electrode 220 , in the 10 is shown, and the second welding electrode 720 is equal to the second welding electrode 320 , in the 12 is shown. In particular, the first welding electrode contains 620 a body 622 and a welding side 624 structurally equal to the body 222 and the welding side 224 the second welding electrode described above 220 are. Analog contains the second welding electrode 720 a body 722 and a welding side 724 structurally equal to the body 322 and the welding side 324 the second welding electrode described above 320 are. Therefore, in 16 - 17 corresponding reference numerals are used to describe structural aspects of the first and second welding electrodes 620 . 720 to designate those equal to those of the second welding electrodes described above 220 . 320 and to incorporate the above disclosure with respect to these similar structural attributes. Because of the structural similarity between the two electrodes 220 . 620 . 320 . 720 becomes a redundant description of the first and second welding electrodes 620 . 720 from 16 - 17 not needed here.

The first and second geometries of the welding pages 624 . 724 can be milled and restored by the deteriorated welding side 624 . 724 in the first or second milling cutter holding fixture 32 . 34 of the milling tool 10 be included and then the tool 10 around the axes 634 . 734 the welding pages 624 . 724 is turned around. In particular, the first welding side 624 through the first shearing surfaces 68 the one or more Fräsfurchen 58 milled and the second welding side 724 is through the second shear surfaces 70 milled. In this way and in a very similar way as in 10 is the central plateau 632 the first welding side 624 engaged in a corresponding engagement extending at least over part of the distance from the leading edge 76 to the trailing edge 78 of the lower end portion 72 the first shearing surfaces 68 the one or more Fräsfurchen 58 extends, and the rotation of the milling tool 10 shears off weld side material to expose new weld side material and to restore the first weld side geometry. Analogously, in a very similar way as in 12 the central plateau 732 and the multitude of terraces 740 the second welding side 724 engaged in appropriate interventions, extending at least over part of the distance from the leading edge 90 to the trailing edge 92 of the lower end portion 86 the second shearing surfaces 70 the one or more Fräsfurchen 58 extend, and the rotation of the milling tool 10 shears off weld side material to expose new weld side material and to restore the second weld side geometry.

The milling tool 10 can be used to rework a pair of welding electrodes, as needed, at the resistance spot welding of a workpiece stack 800 which contains dissimilar workpieces, as in 18 - 26 is shown. The workpiece stack 800 has a first page 802 and a second page 804 on and contains at least one workpiece 806 made of steel and a workpiece 808 made of aluminum, which overlap each other and are adjacent to each other, about a butt interface 810 to be produced by a welding site 812 passes through. The first page 802 of the workpiece stack 800 is through a surface 814 a workpiece made of steel and the second side 804 is through a surface 816 a workpiece made of aluminum provided. The workpiece stack 800 may therefore be a "2T" stack containing only the adjacent pair of workpieces 806 . 808 made of steel and aluminum, or it may be a "3T" stack of adjacent workpieces 806 . 808 made of steel and aluminum plus an additional workpiece 818 made of steel (steel-steel-aluminum, as in 19 shown) or an additional workpiece 820 made of aluminum (steel-aluminum-aluminum, as in 20 as long as the two workpieces having the same parent metal composition are juxtaposed. In other embodiments, the workpiece stack 800 even a "4T" stack, such as steel-steel-steel-aluminum, steel-steel-aluminum-aluminum or steel-aluminum-aluminum-aluminum.

The workpiece 806 Steel includes a steel substrate having any of a wide variety of strengths and grades, either coated or uncoated (ie, blank). The coated or uncoated steel substrate may be hot rolled or cold rolled, and may be made of any steel such as mild steel, interstitial-free steel, sintered-hardened steel, low alloy high-strength steel (HSLA steel), two-phase steel (DP steel ), a complex phase steel (CP steel), a martensite steel (MART steel), a conversion-induced plasticity steel (TRIP steel), a twin-induced plasticity steel (TWIP steel), and a boron steel, for example if the workpiece 806 Made of steel, a pressure-hardened steel (PHS steel) contains. When the steel substrate is coated, it preferably contains a surface layer of zinc (eg, hot-dip galvanized or electrogalvanized), zinc-iron (galvanized), zinc-nickel alloy, nickel, aluminum, or aluminum-silicon -Alloy. Thus, the term "steel workpiece" as used herein includes a wide variety of steel substrates, coated or uncoated, of varying degrees and strengths, and further includes those that have undergone treatments prior to welding, such as annealing, Quenching and / or tempering, for example in the production of pressure-hardened steel. Taking into account the thickness of the steel substrate and any surface coating that may be present, the workpiece has 806 made of steel a thickness 8060 in the range of 0.3 mm to 6.0 mm and narrower from 0.6 mm to 2.5 mm, at least at the welding site 812 ,

The workpiece 808 Aluminum contains an aluminum substrate which is either coated or uncoated (ie bright). The aluminum substrate may be made of a non-alloyed aluminum or an aluminum alloy containing at least 85% by weight of aluminum. Some noteworthy aluminum alloys that can form the coated or uncoated aluminum substrate are an aluminum-magnesium alloy, an aluminum-silicon alloy, an aluminum-magnesium-silicon alloy, or an aluminum-zinc alloy. The aluminum substrate, when coated, preferably contains a surface layer of its native refractory oxide layers or, alternatively, it may contain a surface layer of zinc, tin or a metal oxide conversion layer consisting of oxides of titanium, zirconium, chromium or silicon, as in US 2014/0360986 is described. Considering the thickness of the aluminum substrate and any surface coating that may be present, the workpiece has 808 made of aluminum a thickness 8080 which ranges from 0.3 mm to about 6.0 mm and narrower from 0.5 mm to 3.0 mm, at least at the welding site 812 ,

The aluminum substrate of the workpiece 808 Aluminum may be provided in machined or cast form. For example, the aluminum substrate may consist of a sheet of machined aluminum alloy of a 4xxx, 5xxx, 6xxx or 7xxx series, an extrusion article, a forged article or other machined article. Alternatively, the aluminum substrate may consist of an aluminum alloy casting of a 4xx.x, 5xx.x or 7xx.x series. Some more specific types of aluminum alloys that can form the aluminum substrate include, but are not limited to, AA5182 and AA5754 aluminum-magnesium alloys, AA6011 and AA6022 aluminum-magnesium-silicon alloys, AA7003 and AA7055 aluminum-zinc alloys, and a Aluminum injection-alloy Al-10Si-Mg. The aluminum substrate may also be used, if desired, in a variety of curing steps, including annealing (O), hardening (H) and solution annealing (T). As used herein, the term "aluminum workpiece" therefore includes non-alloyed aluminum and a wide variety of aluminum alloy substrates, coated or uncoated, in various spot-weldable shapes, including processed sheet layers, extrusions, forgings, etc., as well as casting operations , and also includes those that have undergone treatments prior to welding, such as annealing, curing and solutionizing.

The surface 814 of the workpiece made of steel and the surface 816 of the workpiece made of aluminum, which is the first and second side 802 . 804 of the workpiece stack 800 can provide through the adjacent and overlapping workpieces 806 . 808 be presented in steel and aluminum. If the two workpieces 806 . 808 for example, for spot welding in the context of 18 are shown stacked, contains the workpiece 806 made of steel an impact surface 822 and an outer surface 824 , and analogously contains the workpiece 808 made of aluminum an impact surface 826 and an outer surface 828 , The abutment surfaces 822 . 826 of the two workpieces 806 . 808 overlap and contact each other to the impact interface 810 to form, through the weld 812 passes through. The outer outer surfaces 824 . 828 the workpieces 806 . 808 Steel and aluminum on the other hand point away from each other in opposite directions at the welding site 812 and form the surfaces 814 . 816 the workpieces made of steel or aluminum of the workpiece stack 800 ,

The term "impact interface 810 "Is used in the present disclosure in a broad sense and is intended to mean instances of direct and indirect contact between the abutment surfaces 822 . 826 the adjacent workpieces 806 . 808 Made of steel and aluminum. The abutment surfaces 822 . 826 are in direct contact with each other when physically adjacent to each other and not separated by a discrete intervening layer of material. The abutment surfaces 822 . 826 are in indirect contact with each other when separated by a discrete intervening layer of material - and thus do not experience the kind of physical contiguousness at the interface found in direct contact - but are in sufficiently close proximity to each other that resistance spot welding still can be done. Indirect contact between the abutment surfaces 822 . 826 the workpieces 806 . 808 Steel and aluminum typically results when an optional layer of material (not shown) between the abutting surfaces 822 . 826 is applied before the workpieces 806 . 808 when forming the workpiece stack 800 be superimposed.

An intermediate material layer between the abutting surfaces 822 . 826 the adjacent workpieces 806 . 808 steel and aluminum is an uncured but heat curable structural adhesive. Such intermediate material typically has a thickness of 0.1 mm to 2.0 mm, which allows spot welding through the intermediate layer without great difficulty. A structural adhesive may be between the abutment surfaces 822 . 826 the workpieces 806 . 808 Made of steel and aluminum, so that the workpiece stack 800 after spot welding in an ELPO oven or other device can be heated to cure the adhesive and additional adhesion between the workpieces 806 . 808 provide. A specific example of a suitable thermosetting structural adhesive is a thermosetting epoxy that may contain filler particles, such as silica particles, to modify the viscosity or other mechanical properties of the adhesive as it is cured. A variety of thermosetting epoxies are commercially available, including DOW Betamate 1486 , Henkel 5089 and uniseal 2343 include. Of course, other types of materials may form the intermediate material layer instead of a thermosetting structural adhesive.

Of course, the workpiece stack 800 , as in 19 - 20 is shown, not only on containing the workpiece 806 made of steel and the adjacent workpiece 808 limited to aluminum. The workpiece stack 800 can also the additional workpiece 818 made of steel or the additional workpiece 820 made of aluminum - in addition to the adjacent workpieces 806 . 808 made of steel and aluminum alloy - as long as the additional workpiece adjacent to that workpiece 806 . 808 having the same base metal composition; that is, the extra workpiece 818 steel (if present) adjacent to the other workpiece 806 is made of steel and the additional workpiece 820 made of aluminum (if present) adjacent to the other workpiece 808 made of aluminum. With regard to the properties of the additional workpiece, the descriptions of the workpiece 806 made of steel and the workpiece 808 made of aluminum, which have been provided above, on the additional workpiece made of steel or the additional workpiece made of aluminum, which in the workpiece stack 800 may be included, applicable. It should be noted, however, that while the same general descriptions apply, there is no need for the two steel workpieces or the two aluminum 3T stacked workpieces to be machined (eg machined) in terms of composition, thickness, or shape or cast) are identical.

Such as in 19 is shown, the workpiece stack 800 the neighboring workpieces 806 . 808 of steel and aluminum described above, together with the additional workpiece 818 Made of steel containing the workpiece 806 overlapped steel and adjacent thereto is arranged. If the extra workpiece 818 made of steel is so positioned, forming the outer outer surface 828 of the workpiece 808 made of aluminum as before the surface 816 of the aluminum workpiece, which is the second side 804 of the workpiece stack 800 provides while the workpiece 806 made of steel, which is adjacent to the workpiece 808 made of aluminum, now a pair of opposite abutment surfaces 822 . 830 contains. The impact surface 822 of the workpiece 806 made of steel, that of the adjacent impact surface 826 of the workpiece 808 made of aluminum and these contacted (directly or indirectly) forms the impact interface 810 between the two workpieces 806 . 808 Like previously described. The other impact surface 830 of the workpiece 806 made of steel lies an impact surface 832 of the additional workpiece 818 made of steel opposite and makes an overlapping contact (directly or indirectly) with it. Therefore, forms in this particular arrangement of overlapping workpieces 806 . 808 . 818 an outer outer surface 834 of the additional workpiece 818 made of steel now the surface 814 of the workpiece made of steel, which is the first side 802 of the workpiece stack 800 provides.

In another example, as in 20 is shown, the workpiece stack 800 the above-described adjacent workpieces 806 . 808 made of steel and aluminum together with the additional workpiece 820 made of aluminum containing the workpiece 808 overlapped aluminum and adjacent thereto is arranged. If the extra workpiece 820 made of aluminum is thus formed, the outer outer surface 824 of the workpiece 806 made of steel the surface 814 the workpiece made of steel, which as before the first page 802 of the workpiece stack 800 provides while the workpiece 808 made of aluminum adjacent to the workpiece 806 made of steel, now a pair of opposite abutment surfaces 826 . 836 contains. The impact surface 826 of the workpiece 808 made of aluminum, that of the adjacent impact surface 822 of the workpiece 806 made of steel and contacted (directly or indirectly), forms the shock interface 810 between the two workpieces 806 . 808 as described above. The other impact surface 836 of the workpiece 808 made of aluminum lies an impact surface 838 of the additional workpiece 820 made of aluminum and thus forms an overlapping contact (directly or indirectly). Consequently, in this particular arrangement, it forms overlapped workpieces 806 . 808 . 820 an outer outer surface 840 of the additional workpiece 820 made of aluminum now the surface 816 of the aluminum workpiece, which is the second side 804 of the workpiece stack 810 provides.

With reference now to 21 - 22 may be any of the above-described combinations of the first welding electrode 200 . 300 . 420 . 620 (together by reference numerals 901 with welding side 902 designated) and the second welding electrode 220 . 320 . 520 . 720 (together by reference numerals 911 with welding side 912 used) to a resistance spot welding of the workpiece stack 800 perform. The welding side 902 the first welding electrode 901 indicates the first geometry (the one through the first milling fixture 32 of the milling tool 10 can be reworked), and the second welding side 912 the second welding electrode 911 has the second geometry (the one through the second milling fixture 34 of the milling tool 10 can be worked on). The welding electrodes 901 . 911 are supported by a welding gun (not shown) of any suitable type including a C-type or X-type welding gun, and are electrically coupled to a power supply capable of providing electrical power, preferably DC electrical power in the range from 5 kA to 50 kA - between the welding electrodes 901 . 911 and by the Workpiece stack 800 through in accordance with a programmed welding process. The welding gun may also be equipped with coolant lines and associated controllers to direct a coolant fluid, such as water, during spot welding operations to each of the welding electrodes 901 . 911 to deliver.

The method of resistance spot welding begins by placing the first and second welding electrodes 901 . 911 relative to the workpiece stack 800 be positioned so that the first welding side 902 the surface 814 of the workpiece is made of steel and the second welding side 912 the surface 816 the workpiece is made of aluminum, as in 21 is shown. The first welding page 902 and the second welding side 912 then be against their respective workpiece surfaces of steel and aluminum 814 . 816 in alignment with each other with an imposed clamping force at the weld location 812 pressed. The imposed clamping force is preferably in the range of 1780 N to 8896 N (400 lb to 2000 lb) or narrower from 2670 N to 5780 N (600 lb to 1300 lb). Although only the workpieces 806 . 808 made of steel and aluminum, which overlap and lie adjacent to each other, creating the impact interface 810 The following discussion of the method of resistance spot welding applies equally to instances in which the workpiece stack 800 the additional workpiece 818 made of steel or the additional workpiece 820 made of aluminum ( 19 - 20 ), although these additional workpieces 318 . 320 [ 818 . 820 ] have been omitted in the figures for the sake of clarity.

Once the first welding side 902 and the second welding side 912 against the surfaces 814 . 816 the workpieces made of steel or aluminum of the workpiece stack 800 Press, an electric current between the welding electrodes 901 . 911 with the help of their welding sides oriented towards each other 902 . 912 directed. The between the welding electrodes 901 . 911 exchanged electrical current flows through the stack of workpieces 800 through and over the shock interface 810 away, between the adjacent workpieces 806 . 808 made of steel and aluminum. A resistance to the flow of electric current, which is preferably a DC electrical current with a current level ranging from 5 kA to 50 kA, leaves the workpiece 808 made of aluminum melt and produces a molten bath 850 made of molten aluminum within the workpiece 808 made of aluminum, as in 21 is shown. The molten bath 850 made of molten aluminum wets the impact surface 822 of the workpiece 808 Made of steel and penetrates by a distance in the workpiece 808 made of aluminum, which ranges from 20% to 100% of the thickness 8080 of the workpiece 808 made of aluminum at the welding site 812 lies.

After completion of the electric current flow, the molten pool solidifies 850 from molten aluminum to a welded joint 852 that the workpieces 806 . 808 made of steel and aluminum at the welding site 812 by welding, as in 22 shown without the abutment surface 810 between the workpieces 806 . 808 to consume. The welded joint 852 contains again solidified material of the workpiece 808 aluminum and may also include one or more reaction layers of Fe-Al intermetallic compounds adjacent the impact surface 822 of the workpiece 806 Made of steel. The one or more Fe-Al intermetal layers may comprise FeAl ₃ compounds, Fe ₂ Al ₅ compounds, and possibly other intermetallic compounds, and typically have a combined total thickness of 1 μm to 5 μm. The welded joint 852 extends into the workpiece 808 made of aluminum to a distance in, often in the range of 20% to 100% of the thickness 8080 of the workpiece 808 made of aluminum at the welding site 812 lies (with 100% completely through the workpiece 808 made of aluminum), just like the existing molten bath 850 made of molten aluminum.

After passing the electrical current between the welding electrodes 901 . 911 was finished and that of the electrodes 901 . 911 imposed clamping force is no longer needed, the welding electrodes 901 . 911 from their respective surfaces 814 . 816 the workpieces of steel and aluminum withdrawn. The method of resistance spot welding then becomes at other welding locations 812 on the same or on another stack of workpieces 800 repeated. The continued use of the first and second welding electrodes 901 . 911 in resistance spot welding operations finally causes the first welding side 902 and the second welding side 912 become worse. This deterioration of the weld sides 902 . 912 is generally unavoidable and begins at some point, transmitting the electrical current between the welding electrodes 901 . 911 and through the stack of workpieces 800 through it. When the flow of current is disturbed as a result of perceptible weld-side degradation, the formation of the weld becomes 852 disturbed, which makes it difficult to have properties with good strength in the connection 852 consistently reach.

The combination of dissimilar materials in the stack of workpieces 800 and the different weld side geometries of the first and second welding electrodes 901 . 911 lead to different forms of deterioration at the first welding side 902 and the second welding side 912 occur. For example, the first welding side 902 the first welding electrode 901 a macro-deformation in the form of growths due to the high temperatures experienced at the surface 814 of the workpiece occur from steel, and due to the clamping pressure of the welding side 902 is imposed, especially if the workpiece 806 made of steel, a high-strength steel such as DP, TRIP or others. In addition, the first welding side 902 if it is made of a copper alloy, with zinc on the workpiece 806 made of steel, if present, react to a layer of copper-zinc alloy on the welding side 902 which accelerates macrodeformation. The second side of welding 912 the second welding electrode 911 on the other hand, if it is made of a copper alloy, a metallurgical reaction between copper and aluminum can be experienced which forms a reaction product of copper and aluminum. The reaction product of copper and aluminum can be the welding side 912 splinter and attack. In addition, the upright circular ridges 550 from 14 deformed or flattened over time, reflecting the ability of the welding side 524 for conducting electrical current into the stack of workpieces 800 in or out of this impaired.

The first welding page 902 and the second welding side 912 can through the milling tool 10 be reworked periodically whenever it is desired to counteract deterioration of the weld sides and thereby the useful life of the first and second welding electrode 901 . 911 to extend. The first and second welding electrodes 901 . 911 Can be specially reworked after having between 10 and 100 welded joints 852 have trained. That is, the first and second welding electrodes 901 . 911 Can be used to make a first set of welded joints 852 which ranges from 10 to 100, followed by reworking by the milling tool 10 , After reworking, the first and second welding electrodes 901 . 911 used to make a second set of welded joints 852 again in the range of 10 to 100, followed by another reworking with the milling tool 10 , For every welding electrode 901 . 911 This process of welding and reworking may continue until the accumulated consumption of weld side material resulting from the rework operations, the electrodes 901 . 911 placed in a condition in which they are not suitable for further use. Because every reworking operation with the milling tool 10 a material depth in the range of 10 microns to 500 microns, and more preferably from 50 microns to 200 microns away, can each of the welding electrodes 901 . 911 usually withstand between 10 and 500 rework operations before having to be replaced with a new electrode of the same weld side geometry.

Using the milling tool 10 for reworking the first welding side 902 and the second welding side 912 can be performed without the first and second welding electrodes 901 . 911 to remove from the welding gun. The reworking operation involves mounting the milling tool 10 in a rotatable holder. The first and second welding electrodes 901 . 911 then be along the central axis 18 of the through hole 16 of the milling tool 10 simultaneously moved together so that the first side of welding 902 in the first milling holder 32 is added and the second welding side 912 in the second milling holder 34 is recorded as in 23 - 26 for each of the weld side geometry combinations shown previously with reference to FIG 9 - 17 have been described. This picking up the welding pages 902 . 912 brings them in contact with the first and second shear surfaces 68 . 70 , one or more milling grooves 58 of the milling element 14 , 23 - 26 each illustrate the above-described weld-side geometry combinations in their respective milling receptacles 32 . 34 of the milling tool 10 are included. When the first welding side 902 ( 204 . 304 . 424 . 624 ) and the second welding side 912 ( 224 . 324 . 524 . 724 ) are recorded in this way are the axis 212 . 312 . 434 . 634 the first welding side 902 and the axis 234 . 334 . 534 . 734 the second welding side 912 coaxial to the central axis 18 of the through hole 16 of the milling tool 10 aligned.

After picking up the welding pages 902 ( 204 . 304 . 424 . 624 ) and 912 ( 224 . 324 . 524 . 724 ) in their respective milling recordings 32 . 34 become all upright surface features - namely the central plateau 232 . 332 . 432 . 632 . 732 , the variety of terraces 340 . 740 and the upright, circular ridges 550 - which can be present, taken in the appropriate interventions and locked into it, in the appropriate shear surfaces 68 . 70 the one or more Fräsfurchen 58 are defined. The milling tool 10 will then be around the central axis 18 of the through hole 16 rotated at a speed typically in the range of 100 rpm to 1000 rpm or narrower from 200 rpm to 500 rpm for a minimum of one to ten or more narrowly four to six complete revolutions around the axes 212 . 234 . 312 . 334 . 434 . 534 . 634 . 734 the welding pages 902 ( 204 . 304 . 424 . 624 ) and 912 ( 222 . 324 . 524 . 724 ) around. During this rotation, the leading edges become 76 . 90 the shearing surfaces 68 . 70 the one or more Fräsfurchen 58 analogous to the axes 212 . 234 . 312 . 334 . 434 . 534 . 634 . 734 their respective welding pages 902 ( 204 . 304 . 424 . 624 ) and 912 ( 224 . 324 . 524 . 724 ), being in contact with the welding sides 902 ( 204 . 304 . 424 . 624 ) and 912 ( 224 . 324 . 524 . 724 ) stay.

The rotational movement of the leading edges 76 . 90 around the welding sides 902 ( 204 . 304 . 424 . 624 ) and 912 ( 224 . 324 . 524 . 724 ) mills the first and second weld sides 902 . 912 and their associated transitional approaches 208 . 228 . 308 . 328 . 428 . 528 . 628 . 728 to expose new weld side material and to restore the first and second weld side geometry. Any previous deterioration of the welds 902 ( 204 . 304 . 424 . 624 ) and 912 ( 224 . 324 . 524 . 724 ) - be it plastic deformation or deposition of reaction materials (eg, the result of reactions between copper / zinc or copper / aluminum) - is thus virtually eliminated in a single reworking operation which requires no labor or significant process downtime. Once the first welding side 902 ( 204 . 304 . 424 . 624 ) and the second welding side 912 ( 224 . 324 . 524 . 724 ) have been appropriately reworked, the welding electrodes 901 ( 200 . 300 . 420 . 620 ), and 911 ( 220 . 320 . 520 . 720 ) from the first and second milling holder 32 . 34 pulled out and as they are still carried by the welding gun, they can quickly be put back into service.

The foregoing description of preferred exemplary embodiments and specific examples is merely descriptive; they are not intended to limit the scope of the following claims. All terms used in the appended claims are intended to retain their ordinary and general meaning, unless specifically and clearly stated otherwise in the description.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 8525066 [0070]
• US 2014/0360986 [0091]

Claims (10)

A milling tool capable of reworking asymmetric weld side geometries of first and second welding electrodes, the milling tool comprising: a body extending lengthwise along a central axis between a first end and a second end; and a milling element within the body forming a first milling receptacle accessible through a first opening at the first end of the body and further forming a second milling receptacle accessible through a second opening at the second end of the body; Milling element comprises a milling groove containing a cutting blade having axially spaced apart and opposite first and second shear surfaces at least partially defining the first and second milling mounts, respectively, wherein the first shear surface comprises a lower end portion profiled to mill a first weld side geometry and the second shear surface comprises a lower end portion that is contoured to mill a second weld side geometry that is different from the first weld side geometry. The milling tool of claim 1, wherein the first weld side geometry comprises a planar or domed weld side base surface having a diameter between 3mm and 16mm, and wherein the second weld side geometry comprises a domed weld side base surface having a diameter between 8mm and 20mm and further includes a central plateau centered on the domed weld-side base surface. The milling tool of claim 1, wherein the first weld side geometry comprises a planar or domed weld side base surface having a diameter between 3mm and 16mm, and wherein the second weld side geometry comprises a domed weld side base surface having a diameter between 8mm and 20mm and further includes a central plateau centered on the domed weld-side base surface and a plurality of terraces surrounding the central plateau. 3. The milling tool of claim 1, wherein the first weld side geometry comprises a domed weld side base surface having a diameter between 8 mm and 20 mm and further including a central plateau centered on the domed weld side base surface and wherein the second weld side geometry is a domed one Weld-side base surface comprising a diameter between 8 mm and 20 mm and a series of upstanding circular ridges projecting outwardly from the curved weld-side base surface. The milling tool of claim 4, wherein the series of upstanding circular ridges includes between two and ten upright circular ridges, the diameter of which increases from an innermost upright circular ridge to an outermost upstanding circular ridge, the upstanding circular ridges on the domed one Welding side base surface are spaced by a distance of 50 microns to 1800 microns apart and each of the upstanding circular ridges has a ridge height which is in a range of 20 microns to 500 microns. 3. The milling tool of claim 1, wherein the first weld side geometry comprises a domed weld side base surface having a diameter between 8 mm and 20 mm and further including a central plateau centered on the domed weld side base surface and wherein the second weld side geometry is a domed one Weld-side base surface having a diameter between 8 mm and 20 mm and further including a central plateau centered on the curved weld-side base surface and a plurality of terraces surrounding the central plateau. The milling tool of claim 1, wherein the milling element comprises a first milling groove having a first milling blade, a second milling groove having a second milling blade, a third milling groove having a third milling blade and a fourth milling groove having a fourth milling blade, wherein the first, second, third and fourth Scaling blade are spaced apart in the circumferential direction such that each of the first, second, third and fourth Fräsklingen oriented transversely to each of its two circumferentially adjacent Fräsklingen, each of the first, second, third and fourth Fräsklingen axially spaced apart and opposite first and second Shearing surfaces contains, wherein the first Abscherflächen the first, second, third and fourth Fräsklingen define the first Fräsaufnahme and define the second Abscherflächen the first, second, third and fourth Fräsklingen the second Fräsaufnahme. A method of reworking welding electrodes having asymmetrical weld side geometries, the method comprising: providing a milling tool including a body and a cutting element within the body, the cutting element comprising one or more milling grooves forming a first milling receptacle and a second milling receptacle wherein the first milling receptacle is accessible through a first opening at a first end of the body and the second milling receptacle is accessible through a second opening at a second end of the body; a first welding side of a first welding electrode is received in the first milling receptacle of the milling tool; a second welding side of a second welding electrode is received in the second milling receptacle of the milling tool; and rotating the milling tool to mill and restore a first weld side geometry in the first weld side and a second weld side geometry in the second weld side, wherein the first weld side geometry of the first weld side is different from the second weld side geometry of the second weld side. The method of claim 8, wherein rotating the milling tool comprises rotating the milling tool between one and ten complete revolutions about axes of the first and second weld sides such that a depth of material ranging from 10 μm to 500 μm, of both of the first welding side as well as the second welding side during a restoration of the first welding side geometry and the second welding side geometry is removed. The method of claim 8, further comprising: a set of ten to one hundred welds between overlapping and adjacent steel and aluminum workpieces is formed before the first weld side is received in the first milling seat of the milling tool and the second welding side is received in the second milling seat of the milling tool.

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