Method for connecting wire ends of wires of two wire coils and assembly with two wire ends

Abstract

In order to connect wires (2, 5) for feeding to a processing machine, the invention proposes to weld wire ends (1, 4) by orbital welding not continuously, but only in a circumferential surface area (11) with a limited welding depth.

Description

The invention relates to a method and an arrangement for connecting wire ends of wires of two wire coils having the features of the preambles of claims 1 and 14.For the production of, for example, pin-shaped fastening or connecting elements such as, for example, bolts, threaded pins, screws and the like, it is known to unwind wire from a wire coil, to form the wire in a wire processing machine, wire processing device or the like, also to form it in multiple stages, optionally also other than to process it by forming and to separate it from the wire. When the wire coil is used up, a wire from a new wire coil has to be introduced into the wire processing machine, wire processing device or the like for processing, for which purpose a front wire end of the wire from the new wire coil can be connected to a rear wire end of the wire from the used-up wire coil and the wire from the new wire coil can be drawn in or through the wire from the used-up wire coil in the wire processing installation, wire processing device or the like.US 5,992,726 discloses a welding device for welding wire ends of two wires of wire coils. The welding device comprises a clamping device for clamping the two wire ends during welding. The clamping device has two lateral clamping jaws and a support jaw which is moved from below to the wire ends. By means of the welding, when a first wire coil is used up, the wire does not have to be rethreaded, inserted or introduced into a wire processing machine or wire processing device, but rather the wire of a new, second wire coil with the remaining wire can be drawn into the wire processing machine or wire processing device from the used-up first wire coil.It is an object of the invention to propose an alternative method for welding the wire ends of two wires for a subsequent machining of the wire and an arrangement of the wire ends.This object is achieved according to the invention by a method having the features of claim 1 and an arrangement according to claim 14.The method according to the invention, having the features of the preamble of claim 1, for connecting the two wires for supplying the second wire to a processing machine by drawing with the first wire, provides for wire ends of two wires for connecting to a weld seam not to be welded completely over an entire wire cross section, i.e. not to weld the entire end faces of the wire ends, but instead to weld the wire ends to one another only close to the surface, i.e. in at least one surface region, in such a way that a central portion of the end faces of the wire ends remains unwelded. "weld seam" here generally means the weld location at which the weld is carried out. This welding point can be punctiform or planar and the term "weld seam" is not limited here to a specific geometric configuration. By "close to the surface" is meant that the welding is then effected only in an outer region of the cross section of the wire ends. A "surface region" is a region which is bounded on the outside at the wire ends of the wires by the circumferential surface of the wires, in particular starts there, and which extends radially inward with respect to the longitudinal axis of the wires, in particular over less than half of a radius of the two cross sections of the wire ends to be welded and / or not as far as the middle of the two cross sections of the wire ends. This means that a central portion of the welded end faces of the two wires, in particular a region in the center of the cross sections of the wire ends, remains unwelded. The central portion, which remains unwelded, is located in particular in a center of the end faces of the wire ends, but can also be eccentric and / or extend at one or more circumferential points as far as the surface or circumferential surface of the wires. In the latter case, the welding of the wire ends is interrupted at one or more circumferential locations.The term "wire processing machine" also includes wire processing devices such as drawing dies and / or the like.In particular, the wire ends are not moved relative to one another during welding, in particular not toward one another, and / or the wires are not rotated about their longitudinal axes during welding.By "wire" is meant an elongated steel which is thin in relation to its length and which in particular has a circular and, in contrast to a tube, a full-surface cross-section. The two wires can be in the form of rod stock, but in particular in the form of wire coils, i.e. of coils of metal wire. The first wire is then part of a first wire coil and the second wire is part of a second wire coil.With the method according to the invention, the wire ends of the two wires can be welded together quickly, wherein a sufficient tensile strength of the weld is possible to draw a second, new wire, in particular from a second, new wire coil, with the remaining wire of a nearly used-up first wire, in particular a first wire coil, through or into the subsequent wire processing machine. The invention uses the finding that the welding over only a partial region of the wire ends is sufficient for this purpose.As a further advantage, the invention enables the welding of the wire ends in such a way that no welding bead, welding spots or the like protruding outwards beyond the circumference of the unwelded wires are produced, which would impede the drawing in or pulling through of the welding point of the wires through or into the wire processing machine following the welding or would require removal of lateral welding supernatants before the drawing in or through the following wire processing machine.The dependent claims are subject to advantageous embodiments and developments of the invention specified in claim 1.A continuous welding of the wire ends in a circumferential direction, i.e. over the entire circumference thereof, is preferred, which leads to a uniform distribution of occurring forces.Preferably, the wire ends are welded to one another by arc welding and in particular by inert gas welding.A preferred welding method according to the invention for connecting the wire ends of the two wires is orbital welding. Orbital welding is an automated arc inert gas welding around the two wires or wire ends, in particular around 360°. Preferably, the wire ends are welded around the circumference without interruption of the weld over 360°, the invention not excluding interrupted welding. Moreover, embodiments of the invention which do not have all features of orbital welding are also possible.Welding methods preferred according to the invention are a tungsten inert gas welding (TIG) or a metal inert gas welding (MSG). These welding methods are preferably carried out as orbital welds.One embodiment of the invention provides that an arc for welding the two wire ends is guided around the wire ends in such a way that the wire ends are welded close to the surface and the central section of the end faces of the wire ends remains unwelded. A radial depth of the weld or a depth of the weld transversely to the wires can be adjusted by a strength of a welding current and a rotational speed of the arc around the wire ends.According to the invention, the wire ends can be connected with a constant, a continuous or at least uninterrupted welding current. One embodiment of the invention provides a pulsed welding current. That is, the welding current has interruptions. In the case of an arc which is circulated around the wire ends, the weld can nevertheless be continuous if the interruptions in the current are short and the rotational speed is not too high. However, it is also possible to carry out interrupted welding in the circumferential direction with one welding point or a plurality of welding points or a (multiple) interrupted welding line or welding bead.Arc welding with a pulsed welding current is also possible, wherein the arc is guided several times, for example two to three times, around the wire ends of the wires to be connected and the welding current is pulsed in such a way that welding is carried out between the previously welded points on each further revolution. The weld then arises during different revolutions at different circumferential locations of the wires.Unlike in the case of customary arc welding methods or also other welding methods, no welding filler material is supplied in embodiments of the invention. This makes it easier not to produce any welding bead, welding spots or the like which project outwards beyond the circumference of the unwelded wires and which would have to be removed / n before the wire can be drawn into a wire processing machine following the welding.In order to obtain easily weldable wire ends in radial planes, transverse planes or also planes oriented differently with respect to the wires or generally surfaces, one embodiment of the invention provides for end sections of the two wires to be cut off from the wires, in particular sheared off, before the welding.One embodiment of the invention provides for the two wires connected to form a wire by the welding according to the invention to be drawn through. By "pulling through" is meant herein wire pulling as a manufacturing method, which is effected in particular by a drawing die. The drawing through achieves a wire cross section defined in shape and size.A further development of the invention provides that, as a result of the wires welded according to the invention to form a wire being drawn through, a cavity is formed in the unwelded central portion between or within the welded surface region or regions between the end faces of the wire ends of the welded wires. The cavity is formed by a reduction in the cross-section of the wires during pulling, which stretches the wire / wires, and by tensile forces which act on the wire during pulling.The arrangement according to the invention having the features of claim 14 has wire ends of two wires connected by welding, in particular of two wires of two wire coils. In particular, the wire ends are connected according to one or more variants of the method explained above. The arrangement according to the invention has the two wire ends which are in particular arranged flush with their end faces lying against one another or at a distance and are welded continuously without interruptions or intermittently circumferentially in a surface region or in surface regions separated by interruptions. During welding, the wires are preferably not turned, but the welding is performed circumferentially around the wire ends. The wire ends are preferably held immovable with respect to each other during welding. A central portion of end surfaces of the wire ends between or within the welded surface areas of the wires is unsealed. In particular, a cavity exists between the end faces of the wire ends in the unwelded central portion between the welded surface regions or within the circumferential welded surface region.The features and combinations of features mentioned above in the description, embodiments and configurations of the invention, and the features and combinations of features mentioned below in the description of the figures and / or shown in a figure, can be used not only in the respectively specified or shown combination, but also in fundamentally any other combinations or else individually. Embodiments of the invention are possible which do not have all the features of a dependent claim. Also, individual features of a claim may be replaced by other disclosed features or combinations of features. Embodiments of the invention which do not have all features of the exemplary embodiment but rather a fundamentally arbitrary part of the features of the exemplary embodiment which are characterized are possible.The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing. The figures show successive method steps of the method according to the invention, some method steps being optional. The following are shown: FIG. 1 shows a severing of an end section of a wire as an optional first method step of the method according to the invention; FIG. 2 shows welding wire ends of two wires of two wire coils in a surface region according to the invention; FIG. 3 shows a drawing through of the wires after the welding as an optional method step of the method according to the invention; and FIG. 4 shows an arrangement of wire ends of wires of two wire coils welded in a surface region according to the invention.With the method according to the invention, a rear wire end 1 of a first wire 2 of a first wire coil, not shown in detail, is connected to a front wire end 4 of a second wire 5 of a second wire coil 6 by welding to form a wire 2, 5. The method is to draw the second wire 5 from the second wire coil 6 with the first wire 2 through a die 7 (FIG. 3 ) when the first wire coil is used up. The second wire coil 6 is a new wire coil 6, and the second wire 5 of the new, second wire coil 6 does not have to be threaded into the die 7 with a draw angle. The draw angle is a tapered wire section in an end section of the second wire 5 adjoining the front wire end 4, which, before being threaded into or through the die 7, has to be formed by forming on the second wire 5 if the new second wire 5 is not drawn with the preceding first wire 2 by the used-up wire coil, not shown, through the die 7. The welding of the wire ends 1, 4 replaces the time-consuming forming of the drawing angles and threading into the die 7. the rear wire end 1 of the first wire 2 is an end of the first wire 2 which, during unwinding from the first wire coil, is finally unwound from the first wire coil when the first wire coil is completely unwound, i.e. used up. The front wire end 4 of the second wire 5 is an end of the second wire 5 which is first unwound during unwinding from the second, new wire coil 6.The die 7 is a forming tool having an opening 8 which typically tapers in a funnel shape in a direction of pulling through and the cross section of which forms a cross section of the wire 2, 5. The cross section of the wire 2, 5 is changed, normally reduced, when it is pulled through the die 7, wherein the cross section can be reduced to scale or a shape of the cross section of the wire 2, 5 can also be changed. The die 7 can also be referred to as a die.The pulling through is a tension-compression forming method, by means of which the wire 2, 5 receives a cross section determined in shape and size by the opening 8 of the die 7 for further processing of the wire 2, 5. In particular, after the wire 2, 5 has been drawn through, it is further processed to form pin-shaped fastening or connecting elements such as, for example, bolts, threaded pins, screws or the like. For this purpose, the wire 2, 5 is in particular shaped, for example a thread is rolled onto the wire 2, 5 and / or a head or a collar is compressed onto the wire 2, 5 (not shown). For this purpose, blanks of the fastening or connecting elements are cut off from the wire 2, 5, for example sheared off (not shown).FIG. 2 shows the welding of the two wire ends 1, 4. in the exemplary embodiment, the wire ends 1, 4 of the two wires 2, 5 are joined according to the invention only near the surface by orbital welding, that is to say by an arc inert gas welding method in which an arc 9 for welding is led around the two wire ends 1, 4 in an inert gas atmosphere, as a result of which the weld seam 3 is formed. The exemplary embodiment of the invention provides a circumferential tungsten inert gas welding (TIG) for welding the wire ends 1, 4 of the two wires 2, 5, so that the weld seam 3 is configured continuously and circumferentially in the form of a circular ring.The arc 9 for welding the wire ends 1, 4 is wound around the two wire ends 1, 4 by at least one full revolution, i.e. by at least 360° in a circumferential direction. In the exemplary embodiment, the arc 9 for welding the wire ends 1, 4 is led around the two wire ends 1, 4 by more than 360°, namely approximately twice to three times.According to the invention, no welding filler material is supplied.The welding is carried out in such a way that no welding points, welding beads or the like of the weld seam 3 project radially beyond a circumference of the two wires 2, 5, so that the wires 2, 5 can be pulled through the opening 8 of the die 7 without further machining after the welding of their wire ends 1, 4. The welding can be carried out in such a way that a circumferential, channel-like depression is produced at the welding seam 3. Alternatively, the weld seam 3 has the same outer diameter as the wires 2, 5 outside the weld.During welding, the two wires 2, 5 are clamped in place in clamping jaws 10-in the embodiment fixed and fixed against rotation-at a distance from their wire ends 1, 4 and thus at a distance from the welding point. The wire ends 1, 4 can abut each other or have a small distance from each other.A welding current for generating the arc 9 for welding the wire ends 1, 4 of the two wires 2, 5 can be continuous or at least uninterrupted. In the exemplary embodiment, the arc 9 is generated with a pulsed welding current, i.e. the welding current is interrupted. A type of spot welding is therefore carried out with welding points distributed over the circumference of the wires 2, 5, which, however, can be so close to one another that they merge into one another and the continuous weld 3 is produced over the circumference of the wires 2, 5. In particular, in the case of a plurality of revolutions of the arc 9 for welding the wire ends 1, 4 of the two wires 2, 5 with the pulsed welding current, the welding points are placed between the welding points of a preceding revolution in a subsequent revolution.According to the invention, the wires 2, 5 are not welded through, but rather the welding current and a circumferential speed of the arc 9 around the wires 2, 5 are selected such that the wire ends 1, 4 are welded in a circumferential surface area 11, the weld seam 3, which is radially smaller than a half diameter of the wires 2, 5 such that a central section 12 at end faces of the wire ends 1, 4 within the circumferential welded surface area 11 remains unwelded. For example, a welding depth, i.e. a dimension of the circumferential welded surface region 11 radially with respect to the wires 2, 5, is approximately a quarter of the diameter of the wires 2, 5 or somewhat less.Before the welding of the wire ends 1, 4, end sections 13 of the wires 2, 5 are cut off in order to ensure radial end faces for welding at the wire ends 1, 4. In the exemplary embodiment, the end sections 13 of the wires 2, 5 are separated from the wires 2, 5 by shearing with a separating shear 14. FIG. 1 shows the shearing of the end section 13 at the front wire end 4 of the new, second wire 5. the end section 13 at the rear wire end 1 of the first wire 2 of the used-up first wire coil is likewise cut off (not shown). The second wire coil 6 is shown in reduced form in FIG. 1.After welding their wire ends 1, 4, the two wires 2, 5 connected to form a wire 2, 5 are drawn through the opening 8 of the die 7, wherein the diameter or generally a cross section of the wire 2, 5 is reduced and the wire 2, 5 is elongated, i.e. becomes longer. In this case, a cavity 15 is formed between the end faces of the wire ends 1, 4 in the unwelded central section 12 within the circumferential, welded surface region 11 of the wires 2, 5 or of the wire ends 1, 4. The wire ends 1, 4 of the two wires 2, 5 connected by orbital welding in the circumferential surface region 11 with the cavity 15 within the circumferential welded surface region 11 between the end faces of the two wire ends 1, 4 forms an arrangement according to the invention, wherein the wires 2, 5 or end sections of the two wires 2, 5 or sections of the wires 2, 5 adjoining on both sides of the welding point can be understood as components of the arrangement according to the invention.In the exemplary embodiment, a diameter of the wires 2, 5 is between approximately 5-20 mm, wherein wires with angular cross-sections can also be welded according to the invention.List of reference characters1 Rear wire end 2 First wire 3 Weld seam 4 Front wire end 5 Second wire 6 Second wire coil 7 Die 8 Opening 9 Arc 10 Clamping jaw 11 Surface region 12 Central portion 13 End portion 14 Cutting scissors 15 CavityReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 5,992,726

[0003]

Claims

A method for connecting wire ends (1, 4) of a first wire (2) and a second wire (5) for connecting the two wires (2, 5) for supplying the second wire (5) to a processing machine by drawing with the first wire (2), wherein the wire ends (1, 4) are welded to each other with a weld seam (3), characterized in that the wire ends (1, 4) are welded only near the surface in such a way that a central portion (12) of end faces of the wire ends (1, 4) remains unwelded.Method according to claim 1, characterised in that the wire ends (1, 4) are welded together over their entire circumference.Method according to claim 1 or 2, characterised in that the wire ends (1, 4) are connected by arc welding, in particular inert gas welding.Method according to one or more of the preceding claims, characterized in that the wire ends (1, 4) are joined by orbital welding.Method according to one or more of the preceding claims, characterized in that the wire ends (1, 4) are joined by tungsten inert gas welding or by metal inert gas welding.Method according to one or more of the preceding claims, characterized in that the wire ends (1, 4) are welded to one another by means of an arc (9) which is moved circumferentially around the wires (2, 5).Method according to one or more of the preceding claims, characterized in that a welding current is pulsed.Method according to Claim 7, characterized in that the arc (9) is guided around the wires (2, 5) several times and in such a way that the weld seam (3) is produced at different circumferential locations of the wires (2, 5) during different revolutions.Method according to one or more of the preceding claims, characterized in that no welding filler material is supplied during welding.Method according to one or more of the preceding claims, characterized in that the weld seam (3) does not project beyond a circumference of the connected wires (2, 5).Method according to one or more of the preceding claims, characterized in that end sections (13) of the two wires (2, 5) are cut off, in particular sheared off, before welding.Method according to one or more of the preceding claims, characterized in that the wires (2, 5) are formed by drawing after welding.Method according to claim 12, characterised in that a cavity (15) is formed in the unwelded central section (12) between the wire ends (1, 4) welded in the surface region (11) as a result of the pulling.Arrangement with two wire ends (1, 4) of two wires (2, 5), characterized in that the wire ends (1, 4) are welded according to the method according to one or more of claims 1 to 13, in that a central section (12) of end faces of the wire ends (1, 4) is unwelded, and in that a cavity (15) exists in the unwelded central section (12) between the wire ends (1, 4).

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