DE102012001778A1 - Joining two metal sheet-type workpieces, by placing edge regions of workpieces to be joined at distance from one another, and introducing wire-shaped filler material into a zone between the edge regions before or during the joining process - Google Patents

Abstract

The method comprises placing edge regions (3, 4) of workpieces (1, 2) to be joined at a distance from one another, introducing a wire-shaped filler material (11) into a zone between the edge regions before or during the joining process, heating the edge regions and the filler material to a predefined joining temperature by a first frictional element (5) that moves in relation to the edge regions and the filler material, subjecting the edge regions and the filler material to a certain contact pressure (6), and joining the edge regions and the filler material while being deformed. The method comprises placing edge regions (3, 4) of workpieces (1, 2) to be joined at a distance from one another, introducing a wire-shaped filler material (11) into a zone between the edge regions before or during the joining process, heating the edge regions and the filler material to a predefined joining temperature by a first frictional element (5) that moves in relation to the edge regions and the filler material, subjecting the edge regions and the filler material to a certain contact pressure (6), and joining the edge regions and the filler material while being deformed. The relative movement of the first friction element is applied by a rotation, twisting, an oscillation and/or a longitudinal movement along the edge regions. An additional friction element for heating the edge regions to be joined to the joining temperature before the first friction element is applied on the edge regions. The edge regions are heated by an external heat source such as resistive heating, inductive heating, gas flame, hot gas, laser, arc, electron beam, plasma jet and/or scorching contact. The joined edge regions in the heated state are smoothed by a smoothing element, which executes the relative movement to the edge regions. A rod-shaped element, a cylindrical shaped element, or a roll-shaped element is used as the first friction element, the additional friction element and/or the smoothing element with an end surface providing a radius, where the end surface is applied opposite to the edge regions. The first friction element is moved in a rotating or oscillating relative movement to the edge regions and in a longitudinal movement along the edge regions. The edge regions are rectilinearly formed. The first friction element is supported on the rear side of the workpieces by the additional friction element. Regions of the workpieces to be joined and the filler material are heated to a plasticizing temperature.

Description

The invention relates to a method for joining two substantially sheet-like workpieces.

For cohesive joining of sheets or similar workpieces both melt and pressure welding can be used.

In the fusion welding process, a common molten bath of the two bonding partners is formed, with optional addition of an additional material, usually in the form of a welding wire. This then produces a melt-solidification structure. The temperature load of the components lies in the joining area in the amount of the melting temperatures of the materials to be joined.

In pressure welding process in addition to the heating by various heat sources, such as electrical resistance heating, the material brought to softening temperature and pressed together by a contact pressure, whereby a welded joint is formed.

In the known friction stir welding, the materials to be joined are heated by a stirring process and stirred together in Schweißbbereich. However, this method is limited to certain, easily deformable materials and minimum material thicknesses.

In cold pressure welding, there is also a limitation to softer materials and certain material thicknesses.

The joining of thin-walled workpieces, in particular the joining of sheets, requires special measures, since the material volume provided by the workpieces in the joining area is very small and since damage to the adjacent areas of the sheets must be avoided. It has therefore been proposed in the friction welding already to widen the edge of the metal tube before friction welding for joining thin-walled metal tubes with other bodies to prevent incision. This is in the DE 38 02 300 C1 described. Another method, in which the contact zone is made as large as possible with a friction tool, shows the EP 1 236 533 A1 ,

The invention has for its object to provide a method for joining two substantially sheet-like workpieces, which requires a low mechanical complexity with a simple structure and simple, cost-effective applicability and allows a secure joining of the sheet-like workpieces.

According to the invention the object is achieved by the combination of features of claim 1, the dependent claims show further advantageous embodiments of the invention.

According to the invention, it is provided that the edge regions of the sheet-like workpieces to be joined are each crimped out of a plane of the respective workpiece or deformed by up to 90 °. Thus, a narrow edge region is reshaped, although the joining seam to be achieved in the finished state is such that the two plate-like workpieces are joined together in abutting position and with constant thickness. As a result of the method according to the invention, there is thus essentially no material thickening of the two sheet-like workpieces in the finished state of the joining seam (provided that they have the same thickness).

Beading is understood in the context of the invention, the folding of the edges of sheets or tubes by up to 90 °. There is thus a right-angled bending of the edge by Winkeligstellen the workpiece edges of the sheet metal parts in the joining seam. According to the invention, the joint seam can be rectilinear or curved. In any case, by flanging or forming a rising from the plane of the sheet-like workpieces edge is formed.

In the method according to the invention, the edge regions to be joined are subsequently applied against each other and thus positioned. Subsequently, the edge regions are heated by means of a friction element to a predetermined bonding temperature and thereby acted upon by a contact pressure. The friction element is displaced in a relative movement to the edge regions. Due to the frictional heat, the edge areas are heated and plasticized. The applied by the friction element contact pressure, which acts perpendicular to a center plane of the workpieces and thus presses on the deformed or flanged edge regions, thereby leading to a deformation of the material of the edge regions and thus to a flattening of the edge regions. The material of the formed or crimped edge regions thus serves as a joining material for joining the workpieces.

According to the invention, the friction element is pressed onto the deformed or flanged edge regions on the face side; in contrast to the prior art, it is not located between the flanged edges or deformed, highly curved edge regions.

In a particularly favorable embodiment of the invention, it is provided that the relative movement of the friction element to the edge regions is effected by a rotation and / or rotation and / or oscillation of the friction element. This relative movement generates the frictional heat required for joining. In addition, a relative movement can be effected by a longitudinal movement of the friction element along the edge regions in order to produce a longer joining seam.

The invention is thus suitable both for joining longer edge regions to form a longer joint seam and for selective or spatially limited joining of the workpieces. Thus, it is also possible to produce spot welds by the friction welding method according to the invention. In this case, the edge regions to be joined, flanged or deformed are correspondingly short, be it in a linear direction or in the form of round or part-circular regions.

Depending on the joining parameters, in particular as a function of the geometry and the material of the workpieces, it may be favorable in a further development of the method according to the invention to additionally heat the edge regions either by means of an external heat source or by means of an additional friction element, which during a longitudinal movement of the first , above mentioned friction elements before this is moved to warm. When heated by means of an external heat source, resistance heating, inductive heating, flame (gas flame) heating, hot gas, laser, electric arc, electron beam, plasma jet, or by Schmorkontakte, similar to the flash butt welding can be used.

In order to produce a smooth, non-raised joint seam, which has substantially the same thickness as the workpieces, it may be favorable to smooth the joined edge regions in the heated state by means of a smoothing element. The smoothing element can also perform a relative movement to the edge regions, similar to a roller or a rotating, to be moved along the longitudinal seam pin.

In a preferred embodiment of the invention, either a rod-shaped or a roller-shaped or a roller-shaped element is used as the first friction element and / or as an additional friction element and / or as a smoothing element. When using a rod-shaped element, the axis of rotation is arranged perpendicular to the median plane of the workpieces, it is advantageous if the end face of the rod-shaped element is chamfered or provided with a radius.

According to the invention, the relative movement can also be generated by an oscillating movement of the first friction element.

For joining very thin-walled sheet-like workpieces or for joining edge regions which are inaccurate or imprecise in geometry, it may be advantageous if at least one filler material is introduced between the edge regions, for example in the form of a wire, before or during the joining process.

In order to machine thick workpieces, it may be favorable, in addition to the first friction element, to provide a second friction element on the back of the workpiece, which not only has a supporting function but additionally a friction function.

According to the invention, it has proved to be particularly favorable, in particular, when the friction element is cylindrical or wheel-shaped, as this can provide an increased relative movement for plasticizing the seam area.

• – Es muss kein Zusatzwerkstoff verwendet werden.
• – Geringere Wärmebeeinflussung als bei Schmelzschweißverfahren.
• – Es entsteht eine I-Stoßverbindung mit günstigem Kraftfluss.
• – Geringer maschineller Aufwand.
• – Bei hoher Drehzahl oder Relativgeschwindigkeit zwischen Reibelement und Werkstück sowie optionaler zusätzlicher Wärmeeinbringung sind hohe Schweißgeschwindigkeiten erreichbar.
• – Die Naht kann mit glatter Nahtoberfläche ausgeführt werden, dadurch keine Kerbwirkung der Naht, es muss keine Überlappnaht wie bei anderen Verfahren gefertigt werden, dadurch Materialeinsparung.
• – Für sehr viele, auch schwer schweißbare Werkstoffe wie Al oder Cu einsetzbar.
• – Feinkörniges Nahtgefüge durch Umformvorgang.
• – Kein Schutzgas erforderlich.
• – Vorhandene Oxidschichten werden durch den Reibvorgang sicher entfernt.
• – Kein Schutz vor Lichtbogen- oder Laserstrahlung notwendig.
• – Zwangslagen problemlos schweißbar, da kein flüssiges Schmelzbad.

The method according to the invention has, inter alia, the following advantages:

• - There is no need to use filler material.
• - Lower heat influence than fusion welding.
• - It creates an I-butt connection with favorable power flow.
• - Low mechanical effort.
• - At high speed or relative speed between friction and workpiece and optional additional heat input high welding speeds can be achieved.
• - The seam can be made with a smooth seam surface, thus no notch effect of the seam, it no overlap seam must be made as in other methods, thereby saving material.
• - Can be used for many, even difficult-to-weld materials such as Al or Cu.
• - Fine-grained seam structure by forming process.
• - No inert gas required.
• - Existing oxide layers are safely removed by the rubbing process.
• - No protection against arc or laser radiation necessary.
• - Forced situations easily weldable, since no liquid melt.

In the following the invention will be described by means of embodiments in conjunction with the drawing. Showing:

1 a schematic side view of two flanged and positioned workpieces,

2 a side view, analog 1 , with application of a first friction element,

3 a side view of the situation of 1 and 2 during the joining process,

4 a side view, analog 3 , with a roller-shaped or disc-shaped friction element,

5 a plan view of the situation according to 3 .

6 a plan view, analog 5 , with disc-shaped friction element according to 4 .

7 a side view, analog 3 , with additional heat source and smoothing element,

8th a side view with a point-shaped joint,

9 a side view with additional material,

10 a representation of another embodiment analog 9 .

11 a side view according to 10 .

12 a representation of another embodiment,

13 a side view according to 12 .

14 a schematic side view, analog 9 , an embodiment with a profiled friction element, and

15 a view, analog 14 , another processing situation.

The 1 shows two juxtaposed sheet-metal workpieces 1 and 2 , their edge areas to be joined 3 . 4 flanged, folded or reshaped. It can be seen that the reshaped edge areas 3 . 4 essentially perpendicular to the respective median plane 12 the workpieces 1 and 2 extend. According to the invention, a lesser beading of the edge regions can also take place, so that the flanging angle can be 90 ° or less.

The 2 shows the next method step, in which a first friction element 5 on the edge areas 3 and 4 is put on. The first friction element 5 is rod-shaped and rounded at its end face and is about an axis of rotation 13 rotated to produce the required frictional heat. In addition, a pressing by means of a contact pressure or a contact force 6 , It can be seen that the contact pressure 6 perpendicular to the median plane 12 is applied and thus in the direction of the edge areas 3 and 4 , This results in a squeezing of the material heated to Plastifizierungstemperatur material of the edge regions 3 and 4 , as in the side view of 3 is shown. The first friction element 5 is in the feed direction 7 moved by a longitudinal movement, in addition to the rotation about the axis of rotation 13 to produce an elongated joint seam.

The 4 shows a design variant with a disc-shaped friction element 5 which is about a rotation axis 14 is rotated, which in a plane parallel to the median plane 12 is arranged. It also becomes a contact pressure 6 applied. The disk-shaped friction element is in the feed direction 7 emotional. The relative movement between the friction element 5 and the edge areas 3 and 4 takes place by a suitably high speed around the axis of rotation 14 so that the friction element 5 along the edge areas 3 and 4 not rolled, but is moved in rotation.

The 5 shows a plan view of the situation of 3 with representation of the finished joint seam 10 , It turns out that the joint seam 10 has a thickness which is the material thickness of the workpieces 1 and 2 is equal to.

In 6 is the in 4 shown situation shown in plan view.

In 7 is schematically an additional heat source 8th shown which the edge areas 3 and 4 additionally heated before this with the first friction element 5 get in touch.

In feed direction 7 behind the first friction element 5 is a smoothing element 9 arranged, which the finished joint seam 10 smoothes. The smoothing element 9 may also have a relative movement, it may also be designed as a rolling roller or in a similar form. Also can on the smoothing element 9 a contact pressure 6 be applied.

While in the embodiments described above, the joint seam is formed as a longitudinal seam, which shows 8th a view, analog 4 , with a substantially point-shaped crimping point. This is by properly forming a limited, small area of the workpieces 1 respectively. 2 generated.

The 9 shows an additional embodiment variant in which a filler material 11 , For example, in the form of a wire, in the joining area between the workpieces 1 and 2 is inserted to add additional material.

For welding thicker sheets 1 . 2 and a good welding of the sheets 1 . 2 On the underside of the seam it is possible to weld with two friction elements 5 from top and bottom to edit. This results in an even better connection of the filler material with the sheets 1 . 2 , The material is plasticized by both friction elements and welded to the sheet edges in a crimping seam, as in the 10 and 11 is shown. For simplicity, the flange is not shown. The second friction element has both a support function and a friction and forming function.

In a further variant of the invention for overlapping sheets with through-welding by an upper sheet (s. 12 and 13 ) become two overlapping sheets 1 . 2 welded by a friction element 5 the upper sheet 1 and a small part of the lower sheet 2 plasticized by friction and in the upper 1 and something in the bottom 2 Sheet penetrates and the plasticized material of the two sheets 1 . 2 through the friction element 5 is squeezed into each other. This results in a welded joint, which can be designed as a step seam or point seam or continuous seam. It may be convenient, the edges of the friction element 5 provided with a radius, as a result, the transition of the welded area is uniform. Also a V-shaped design of the friction element 5 is possible to get a narrow seam.

The 14 shows an embodiment in which a roller-shaped or wheel-shaped friction element 5 which is used around its axis of rotation 14 is set in rotation. The middle area of the friction element 5 is concave and thus has an annular portion which has a smaller diameter. In the case of the joining process described above, there is thus the possibility of the joining seam 10 form thicker and thus to realize a seam exaggeration. This can be supported by a reinforced flange. In the 14 The view shown is a sectional view analogous to 5 , So that the 14 only the finished joint seam 10 shows.

The 15 shows a situation analog 14 when putting on the friction element 5 on the bent or beaded edge areas 3 . 4 to the in 14 shown seam 10 to create.

According to the invention, the two sheets to be welded are crimped at their joint, collided with the hemming and softened by friction and optionally additional heat sources with a rotating or oscillating friction element, which is designed in rod or disc shape and connected by a contact force to a squeeze.

The rod-shaped friction element is preferably chamfered on its end face or provided with a radius, whereby the material to be formed is more easily detected.

The disk-shaped friction element is preferably moved in synchronism rotating in the feed direction, but can also rotate in opposite directions.

The curl at the joint and its size is preferably carried out so that the deformed in the subsequent friction and squeezing process material fills the joint gap so that a flat surface is formed.

The heating can be influenced by the relative speed of the friction element against the workpieces.

For an increase in the welding speed as well as for the welding of thicker materials, it may be advantageous if the material is additionally preheated before the welding point by further external heat sources.

For this, the following heat sources come into consideration: an additionally used leading friction element and / or resistance heating, inductive heating, gas flame, hot gas, laser, arc, electron beam, plasma jet, Schmorkontakte as in flash butt welding etc.

It can be advantageous if the seam is subsequently smoothed by a second friction element or a rolling process, preferably while still warm. This is done in the rod-shaped second friction element with an opposite direction of rotation to the first friction element.

In a second disk-shaped friction element, the smoothing process can take place both in the same direction and in the opposite direction relative to the feed direction.

LIST OF REFERENCE NUMBERS

1, 2

workpiece

3, 4

border area

5

first friction element

6

Pressure / pressure force

7

Longitudinal movement / feed direction

8th

heat source

9

smoothing element

10

joint seam

11

Filler / wire

12

midplane

13

axis of rotation

14

axis of rotation

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

• DE 3802300 C1 [0007]
• EP 1236533 A1 [0007]

Claims (10)

Method for joining two substantially sheet-like workpieces ( 1 . 2 ), in which edge areas to be joined ( 3 . 4 ) of the workpieces from a plane of the respective workpiece ( 1 . 2 ) are formed by up to 90 °, wherein the reshaped edge regions ( 3 . 4 ) are placed against each other and in which the edge areas ( 3 . 4 ) subsequently by means of at least a first, a relative movement to the edge regions ( 3 . 4 ) have friction elements ( 5 ) heated to a predetermined joining temperature and with a contact pressure ( 6 ) are applied and added under deformation. A method according to claim 1, characterized in that the relative movement of the first friction element ( 5 ) by rotation and / or rotation and / or oscillation and / or longitudinal movement ( 7 ) along the edge regions ( 3 . 4 ) is applied. A method according to claim 1 or 2, characterized in that for heating the edge areas to be joined ( 3 . 4 ) to the joining temperature before the first friction element ( 5 ) An additional friction element is applied to the edge regions and moved relative to these. Method according to one of claims 1 to 3, characterized in that for heating the edge regions to be joined ( 3 . 4 ) on the joining temperature the edge areas ( 3 . 4 ) by means of an external heat source ( 8th ), in particular by resistance heating, inductive heating, gas flame, hot gas, laser, arc, electron beam, plasma jet and / or Schmorkontakt. Method according to one of claims 1 to 4, characterized in that the joined edge regions ( 3 . 4 ) in the heated state by means of a smoothing element ( 9 ), which has a relative movement to the edge regions ( 3 . 4 ), be smoothed. Method according to one of claims 1 to 5, characterized in that as the first friction element ( 5 ) and / or as an additional friction element and / or as a smoothing element ( 9 ) a rod-shaped element, preferably with a chamfered or radiused end face, which against the edge regions ( 3 . 4 ) or a roll-shaped or cylindrical element is used. Method according to one of claims 1 to 6, characterized in that the first friction element ( 5 ) in a rotating or oscillating relative movement to the edge regions ( 3 . 4 ) and in a longitudinal movement ( 7 ) along the edge regions ( 3 . 4 ) is moved. Method according to one of claims 1 to 7, characterized in that the edge regions ( 3 . 4 ) are formed straight or curved. Method according to one of claims 1 to 8, characterized in that in the region of the edge regions ( 3 . 4 ) before or during the joining process at least one filler material ( 11 ), preferably in the form of a wire. Method according to one of claims 1 to 9, characterized in that the friction element on the back of the workpieces ( 1 . 2 ) is supported by a further friction element.

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