Welding method and welding machine

Abstract

The invention relates to a welding method comprising the steps of: joining a first joining part (1) to a second joining part (2) by means of a pressure welding method, wherein, after the joining, a weld bead (4) is formed on the edge of the joint of the first joining part (1) and of the second joining part (2), the weld bead protruding beyond the surface (3) of the joined first joining part (1) and second joining part (2); and subsequently remelting the weld bead (4) by means of a fusion welding method such that the elevation formed by the protruding weld bead (4) is flattened and / or levelled out. The invention also relates to a welding machine (7) for carrying out such a welding method.

Description

[0001] Welding process and welding machine

[0002] The invention relates to a welding method comprising the step of joining a first joining part to a second joining part by means of a pressure welding method, in which, after joining, a welding bead projecting beyond the surface of the joined first joining part and second joining part is formed at the edge of the joint between the first joining part and the second joining part. The invention also relates to a welding machine for carrying out such a welding method.

[0003] CN 103008897 A describes a composite welding process that combines laser and friction stir welding. In this composite welding process, a first laser beam is directed at the back of a plate to be welded, and a second laser beam is directed at the front of the plates to be welded using a friction stir head. Immediately before welding, the first laser beam softens the part to be welded on the plate to be welded along the welding direction using the friction stir head. The friction stir head then carries out the friction stir welding to join the parts. Finally, the second laser beam remelts the parts that have been welded by friction stir welding.

[0004] The object of the invention is to further develop a welding process in such a way that a welding bead produced by the pressure welding process can be eliminated or at least reduced, thereby improving the quality of the weld seam.

[0005] The object is achieved by a welding method comprising the steps of: joining a first joining part to a second joining part by means of a pressure welding method, in which after the joining a welding bead projecting beyond the surface of the joined first joining part and second joining part is formed at the edge of the joint of the first joining part and the second joining part,

[0006] - subsequent remelting of the welding bead by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or levelled out.

[0007] During pressure welding, the parts to be joined, i.e. the first part to be joined and the second part to be joined, are pressed together with their joining surfaces by means of a force, while and / or after the parts to be joined have been heated in the area of ​​their joining surfaces to a welding temperature at which the parts to be joined are melted in the area of ​​their joining surfaces. Due to the pressing of the parts to be joined together, the molten material of the parts to be joined is, among other things, deformed, whereby part of the molten material of the parts to be joined swells over the surface of the joined parts and thus forms a weld bead which represents a protrusion protruding from the surface of the joined parts.

[0008] In many applications, such a raised area, i.e., such a weld bead, is undesirable. For example, when joining two rotationally symmetrical parts, such as shafts, which are joined end-to-end, the weld beads created during pressure welding can be undesirable for geometric reasons. Until now, such undesirable weld beads have been removed by machining. For example, the undesirable weld beads can be turned off on a lathe or ground off. In some cases, the undesirable weld beads can also be removed by punching.

[0009] Depending on the specific application, turning, grinding or punching off the weld bead may either not be possible, for example due to the component's geometric conditions, or turning, grinding or punching off the weld bead may adversely affect the weld seam quality of the flat welded joint produced using the pressure welding process.

[0010] By carrying out a pressure welding process for joining the first joining part and the second joining part, according to the invention a subsequent remelting of the welding bead by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or compensated, the weld seam quality of the flat welded connection produced in the pressure welding process can be positively influenced in contrast to the prior art.

[0011] According to the invention, a distinction must be made between the pressure weld seam created in the pressure welding process on the contact surfaces of the parts to be joined and the weld bead. The pressure weld seam extends over the entire contact surface between the first part to be joined and the second part to be joined. In contrast, the weld bead is formed by molten and re-solidified material of the first part to be joined and / or the second part to be joined, which in the molten state pushes out of the joint gap from the area of ​​the entire contact surface between the first part to be joined and the second part to be joined due to the pressing process during pressure welding, namely beyond the surface of the first part to be joined and / or the second part to be joined. The weld bead is therefore the portion of material that oozes out of the joint gap during pressure welding.

[0012] When the welding bead is remelted according to the invention by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or leveled out, the actual pressure weld seam is not remelted, but only the portion of the material which protrudes beyond the surface of the first joining part and / or the second joining part and forms the elevation. By remelting, the projecting welding bead can, for example, be flattened so that it protrudes only less or even no longer at all beyond the surface of the joined parts. On the other hand, it can be sufficient if the projecting welding bead is only leveled out, so that, for example, the surface of the welding bead is made more uniform, without the projecting welding bead being flattened.This can be the case, for example, when unwanted solidified weld drops on the surface of the protruding weld bead are removed.

[0013] Remelting does not completely remelt the existing pressure weld. However, the pressure weld may also be only thermally influenced by the additional heat introduced during the fusion welding process. This can therefore represent a post-heat treatment, which may be associated with quenching and / or tempering effects, stress reduction, and / or hardness reduction.

[0014] Conversely, hardening can also be achieved by subsequent quenching, for example, with water or oil. For example, friction-welded drill rods are hardened by inductive heating followed by quenching under a water jet.

[0015] In particular, an improvement in toughness, especially in notched impact strength, can be expected in friction welding.

[0016] Furthermore, this remelting can produce a type of combined joining connection.

[0017] The elevation of the weld bead, which is flattened and / or leveled after remelting using the fusion welding process, can form a final fusion ring, which shrinks after the remelted material of the flattened and / or leveled weld bead has solidified and subsequently cooled, which can lead to increased tensile stress in the material. This can increase potential stress on the joint or the joined component. As a result, this can result in opportunities for lightweight construction, particularly through a possible reduction in wall thickness.

[0018] The fusion welding process can, if necessary, also be carried out manually after the pressure welding process has been carried out automatically in a welding machine. Preferably, however, the fusion welding process can also be carried out automatically after the pressure welding process has been carried out automatically in a welding machine.

[0019] Accordingly, the welding process may comprise the following steps:

[0020] - automatic joining of a first joining part to a second joining part by means of a pressure welding process in a welding machine, in which after joining a welding bead projecting beyond the surface of the joined first joining part and second joining part is formed at the edge of the joint between the first joining part and the second joining part,

[0021] - subsequent automatic remelting of the welding bead by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or levelled out.

[0022] Automatic remelting in the melt welding process can be performed in the same welding machine that also performs the pressure welding process. This has the advantage that the parts joined by the pressure welding process do not have to be removed from the welding machine prior to automatic remelting for the pressure welding process, nor do they have to be fed to a separate welding machine where the automatic remelting would take place. This eliminates the need for transport and also saves transport time.A further advantage can arise if the automatic remelting in the fusion welding process is carried out in the same welding machine that also performs the pressure welding process. This can be achieved by performing the remelting in the fusion welding process while the parts to be joined still retain residual heat from the pressure welding process. This allows the remelting in the fusion welding process to begin at a higher initial temperature. This can have a positive effect on the temperature profile during the fusion welding process, which can lead to positive effects after the remelting of the weld bead.With regard to cycle times, it is also advantageous if the parts to be joined can remain in the welding machine in the previous clamping after pressure welding and if the remelting of the welding bead can also be carried out using the fusion welding process in this original clamping in the welding machine.

[0023] If necessary, the range of materials suitable for welding can be expanded by remelting the welding bead according to the invention.

[0024] A welding machine which is designed and equipped to carry out the pressure welding process also offers the possibility of carrying out the subsequent remelting on the rotating joined component due to the rotatability of the clamping devices of the parts to be joined, whereby this has the advantage that in particular the welding device for carrying out the fusion welding process can be designed to be stationary, i.e. not rotating.

[0025] Contacting the rotating tool or a chip chuck can be achieved with a simple sliding contact, as is common in welding technology. This is also required for most arc welding processes. However, blasting processes do not require contacting.

[0026] However, in a modified version, it is also possible, particularly in the case of small welding beads, to actively guide the welding device around the component, i.e. the joined first joining part and second joining part, in order to carry out the fusion welding process.

[0027] In another variant, the remelting can take place outside the welding machine which is designed and equipped to carry out the pressure welding process, in particular in a separate, second welding machine which is designed and equipped to carry out the fusion welding process.

[0028] This can, for example, save cycle time on the welding machine used for pressure welding. The welding machine used for pressure welding can therefore perform two welds in the same time.

[0029] It can thus be provided that the first step of the basic method, according to which a first joining part is joined to a second joining part by means of a pressure welding process, in which after joining a welding bead projecting beyond the surface of the joined first joining part and second joining part is formed at the edge of the joint between the first joining part and the second joining part, is carried out on a first welding machine. Such a first welding machine can be, for example, a friction welding machine, a resistance welding machine or an MBP welding machine. The second step of the basic method, according to which a melting of the welding bead then takes place by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or leveled out, can be carried out on a second welding machine which is different from the first welding machine.In particular, it can be provided that the second welding machine is positioned in close proximity to the first welding machine, so that only a very short transport route is necessary to transport the component joined from the first welding machine, comprising the first joining part and the second joining part, to the second welding machine. The transfer time can therefore be kept very short and, if necessary, the components joined on the first welding machine can be reworked on the second welding machine while still exhibiting residual heat in order to flatten the weld bead. If it is not necessary or not intended that residual heat from the joined component is to be used, the second welding machine can also be positioned spatially away from the first welding machine.

[0030] Overall, very cost-intensive machining machines can be saved in any case, since, for example, a fusion welding device causes comparatively lower costs than a machining machine.

[0031] As a downstream process, it can also be assumed that the bead melting does not extend the cycle time. In the second step of the process, after which the weld bead is remelted using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled out, the weld bead is reduced in its geometric height, over which the weld bead rises, i.e. protrudes, above the other surface or shell wall of the joined parts. Depending on the individual case, the height of the weld bead can even be reduced to such an extent that the weld bead is almost completely eliminated, i.e. the weld bead is remelted by the remelting to such an extent that it is completely absorbed into the surface of the joined parts.

[0032] In the case of rotationally symmetrical joining parts, such as shafts, pipes or cylinder rods, a circular ring-shaped welding bead can result. Such a circular ring-shaped welding bead can best be machined in the second step of the process, after which the welding bead is melted using a fusion welding process in such a way that the elevation formed by the protruding welding bead is flattened and / or leveled out, by leaving the parts joined in the first step of the process using the pressure welding process in the clamping of the pressure welding machine and allowing the parts to be rotated in this clamping so that the circular ring-shaped welding bead is guided in rotation along a stationary fusion welding device, whereby the welding bead is flattened and / or leveled out over the circumference of the joined parts.

[0033] As an alternative to a fixed fusion welding device, the fusion welding device can also be mounted movably, so that a machining tip of the

[0034] The fusion welding device can be moved along the welding bead, in particular can be moved along automatically. The processing tip of the fusion welding device can be movably mounted, regardless of whether the joined parts are rotatably mounted in the welding machine or are fixedly arranged in the welding machine, in order to move the processing tip of the fusion welding device along the welding bead, in particular to move it automatically.

[0035] In particular, pressure welding processes such as MBP welding or MagnetArc welding and friction welding produce a particularly circular weld bead which can be at least flattened and / or levelled or even completely removed or eliminated by means of the process according to the invention.

[0036] However, the method according to the invention can also be used in other pressure welding processes, such as pressure butt welding, flash butt welding, linear friction welding or friction stir welding.

[0037] In friction stir welding, for example, such a process can be used to remelt / remove the burr that often occurs. The burr is understood as a special form of the weld bead. Deburring in friction stir welding can be made more repeatable and monitored through this process. For example, in friction stir welding, the weld bead can also be a weld bead bead or burr that extends straight along the edges of the two parts to be joined. In a first basic embodiment,

[0038] Pressure welding process a friction welding process is carried out.

[0039] In the friction welding process, the first and second parts to be joined are pressed against each other with their opposing joining surfaces perpendicular to the joining surfaces that form the joint. The two parts to be joined are moved relative to each other transversely to the pressure direction, i.e. in the plane of the joining surfaces. One or both parts can be moved. Due to the movement against each other and the pressure perpendicular to the joining surfaces, friction at the joining surfaces creates heat, which causes the material of the two parts to be joined to be plasticized near the joint. Due to the plasticization, the two parts to be joined are welded together at the joint. Due to the pressing force, material swells out of the joining surface and forms a weld bead that protrudes above the surface of the two parts to be joined.

[0040] In various first variants of the first basic embodiment, the friction welding process can be carried out according to a welding process from the group comprising linear friction welding, friction stir welding, rotary friction welding and orbital friction welding.

[0041] Linear friction welding is a special form of friction welding in which the relative movement of the first and second parts to be joined is a straight movement and therefore not a rotating movement. The two parts to be joined are moved back and forth in the joining plane and are pressed together perpendicular to the joining plane. Linear friction welding is particularly advantageous when parts that are not rotationally symmetrical are to be joined. A special feature of linear friction welding is that the linear relative movement of the first part to be joined with respect to the second part, with simultaneous pressure being applied to the joint, creates a weld bead that is uneven around the circumference of the parts to be joined. This is because significantly more molten, plasticized material is forced out of the joint in the linear back and forth directions than perpendicular to these directions.This results in a weld bead that is very uneven around the circumference. By remelting the uneven weld bead after linear friction welding using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or equalized, the weld bead can also be made more uniform, specifically by flattening and / or equalizing those areas of the weld bead that are higher in the linear back and forth direction of the linear friction welding. The areas of the weld bead that are less high perpendicular to the linear back and forth direction of the linear friction welding can either not be flattened and / or equalized at all or only to a lesser extent.Of course, the uneven elevation can also be compensated or even completely eliminated over the circumference of the uneven welding bead by remelting using the fusion welding process.

[0042] Friction stir welding is a special form of friction welding in which the two parts to be joined are not moved relative to one another under pressure in order to generate frictional heat, but rather a friction tool different from the two parts being joined is used. The friction tool can in particular be designed as a rotating mandrel. This rotating mandrel is inserted into the joining gap between the first part to be joined and the second part to be joined and moved in a rotating manner along the joining gap. The mandrel thus rubs against a first joining surface of the first part to be joined and against a second joining surface of the second part to be joined. The friction creates heat which leads to the material of the first part to be joined plasticising in the area of ​​the joining gap and the material of the second part to be joined plasticising in the area of ​​the joining gap.The rotation of the mandrel not only generates frictional heat, but also mixes the plasticized material of the first joining part with the plasticized material of the second joining part. At the same time, the mandrel is moved along the joining gap between the first and second joining parts in a feed direction. In the process, the plasticized material of both joining parts is mixed and transported against the feed direction into the widened joining gap, where it solidifies to form a linear weld bead or a linear burr. In the second step of a further developed welding process, according to which the welding bead is melted by means of a fusion welding process following friction stir welding in such a way that the elevation formed by the projecting welding bead is flattened and / or leveled out, the material of the linear welding bead or the protruding welding bead lying behind the mandrel in the feed direction of the mandrel can be melted.of the linear ridge and thus flattened and / or leveled.

[0043] Rotational friction welding is a special form of

[0044] Friction welding, in which the relative movement of the first joining part and the second joining part against each other is a rotating movement. At least one of the two joining parts or both joining parts can preferably be rotationally symmetrical components, such as cylinders, pipes or rods. Optionally only one of the two joining parts can be driven in rotation or both joining parts can be driven in rotation. The two joining parts are generally joined end-to-end by rotational friction welding, in that the two joining parts are pressed axially against each other while they rotate relative to each other. This creates a weld bead that is very evenly formed over the circumference.The subsequent remelting of the weld bead after rotary friction welding by means of a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled out can here in particular be carried out immediately after rotary friction welding, preferably in the same clamping setup as the rotary friction welding. In this case, it is particularly expedient if the remelting of the weld bead takes place by means of a fusion welding process with a stationary fusion welding device and the rotating clamping from the rotary friction welding process is used to automatically guide the circumferential weld bead along a processing tip of the fusion welding device by rotating the joined parts. The fusion welding process can therefore be carried out directly in the welding machine in which the previous rotary friction welding was carried out.

[0045] Orbital friction welding is a special form of

[0046] Friction welding, in which the relative movement of the first

[0047] joining part and second joining part relative to each other does not result from a rotating movement of the first joining part and / or the second joining part. Rather, the first joining part and / or the second joining part are each held in a fixed clamping device in which the joining parts do not rotate. This means that joining parts that do not have a rotationally symmetrical shape can be joined in particular. The two joining parts are moved relative to each other in that one clamping of the first joining part is moved relative to the clamping of the second joining part transversely to the joint, and not just in a linear movement as in linear friction welding, but in circular or oval, i.e. orbital movements within the joining plane. The first joining part is therefore moved in circular movements relative to the second joining part and at the same time in the axial direction, i.e. A pressing force is applied perpendicular to the joining plane.During orbital friction welding, a weld bead also forms due to the displacement of the plasticized material molten by the frictional heat during pressing. Removal of this weld bead is not easily possible, for example by conventional turning using a turning tool in the machine, due to the non-rotationally symmetrical shape of the parts to be joined and / or due to the orbital movement of the parts to be joined. On the other hand, with the welding method according to the invention, such a non-rotationally symmetrical weld bead formed during orbital friction welding can be easily removed by remelting the weld bead using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled out or even completely eliminated by the fusion welding.In a second basic embodiment, a resistance welding process is carried out as the pressure welding process.

[0048] In the resistance welding process, the first and second parts to be joined are pressed against each other statically, i.e., without relative movement transverse to the contact direction, with the joining surfaces of both parts facing each other perpendicular to the joining surfaces that form the joint. At the same time, electrical energy is conducted from one part to be joined to the other part across the joint. At the joint, the material of the two joining partners heats up due to the Joule heat that is introduced into the joining partners by the electrical energy. The process according to the invention is particularly useful when used in a resistance welding process in which the joining partners are also pressed against each other with contact force, i.e., contact pressure. Here, too, plasticized material of the joining partners is forced out of the joint gap due to the contact force, and a weld bead forms.Here too, removal of this welding bead, for example by a conventional turning process using a turning tool in the machine, is not easily possible, especially when the parts to be joined are not rotationally symmetrical. On the other hand, with the welding method according to the invention, such a welding bead, which may be non-rotationally symmetrical and which arises during resistance welding, can be easily removed by remelting the welding bead using a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or leveled out or even completely eliminated by the fusion welding. In various second variants of the second basic embodiment, the resistance welding process can be carried out using a welding process from the group comprising resistance butt welding, pressure butt welding and flash butt welding.

[0049] Resistance butt welding is a special form of resistance welding in which the electrically conductive parts to be joined are first pressed together at the joint to ensure a good electrical connection. Once a good electrical connection has been created, electrical energy is passed across the joint so that the areas where the parts are to be joined heat up due to Joule heat until they melt. Once the required temperature has been reached, the current flow can be stopped and the two parts to be joined can be pressed further together perpendicular to the joining surface so that both parts are joined. As a result of the pressing together, plasticized material is forced out of the joint area. This forms the weld bead.Here too, removal of this weld bead, for example by the conventional turning process using a turning tool in the machine, is not easily possible, especially when the parts to be joined are not rotationally symmetrical. On the other hand, such a weld bead, which may not be rotationally symmetrical, can be easily removed with resistance butt welding by remelting the weld bead using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled out or even completely eliminated by the fusion welding. Pressure butt welding is a special form of.

[0050] Resistance welding, similar to

[0051] Resistance butt welding, in which the electrically conductive joining partners are first pressed together at the joint to ensure a good electrical connection. Once a good electrical connection has been created, electrical energy is passed across the joint so that the areas where the joining partners are joined heat up due to Joule heat until they melt. Once the required temperature has been reached, the current flow can be turned off and the two joining partners can be pressed further together perpendicular to the joining surface so that both joining partners are joined. Due to the compression, plasticized material is forced out of the joint area. This forms the weld bead.Here, too, removing this weld bead, for example by conventional turning using a turning tool in the machine, is not easily possible, especially when the parts to be joined are not rotationally symmetrical. However, with pressure butt welding, such a possibly non-rotationally symmetrical weld bead can be easily removed by remelting the weld bead using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled, or even completely eliminated, by the fusion welding.

[0052] Flash butt welding is a special form of resistance welding in which, in contrast to resistance butt welding and pressure butt welding, the two parts to be joined are not pressed together over their entire surface under high pressure at the joint during the flow of electrical energy, but only have loose electrical contact, i.e. only at specific points in individual smaller areas of the joint, so that the electrical energy only flows over a small area of ​​the joint. The result is that there is a very high current density in this smaller partial area, which not only liquefies the material of the parts to be joined in this area, but also partially evaporates it or causes it to be thrown off in the form of material splashes. The parts to be joined are therefore burned off in these areas. This means that a pressing together takes place even while the current is flowing.Once the areas of the joint have been sufficiently heated and enough material from the joining partners has melted, the electrical power is switched off and the two joining partners are pressed together under high pressure to create the joint. This also forms the weld bead. Here too, removal of this weld bead, for example by the usual turning process using a turning tool in the machine, is not easy, especially when the parts to be joined do not have a rotationally symmetrical shape. On the other hand, such a weld bead, which may not be rotationally symmetrical, can be easily removed with flash butt welding by remelting the weld bead using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled out or even completely eliminated by the fusion welding.

[0053] In a third basic embodiment, an MBP welding process is carried out as a pressure welding process.

[0054] The MBP welding process is also known as magnetic arc welding. In the MBP welding process, the two electrically conductive joining partners are brought into contact at their joining surfaces so that electrical energy can be conducted across the joining surfaces. The two joining partners are then moved away from each other and separated so that a gap forms between the two joining partners, across which an arc is created due to the continued current flow. Using an additional magnetic field, the arc can be set in motion so that it moves along the joining surfaces and evenly heats the material of the two joining partners near the joining surfaces until it melts and plasticizes. The two joining partners are then pressed against each other with pressure and both the current flow and the magnetic field are switched off. This also forms the weld bead here.Here, too, removing this weld bead, for example by conventional turning using a turning tool in the machine, is not easily possible, especially when the parts to be joined are not rotationally symmetrical. However, with the MBP welding process, such a possibly non-rotationally symmetrical weld bead can be easily removed by remelting the weld bead using a fusion welding process in such a way that the elevation formed by the protruding weld bead is flattened and / or leveled, or even completely eliminated, by the fusion welding.

[0055] In the second process step of the basic welding process, after which a subsequent remelting of the welding bead takes place by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead is flattened and / or leveled out, laser welding can be carried out as a further development of the fusion welding process.

[0056] In laser welding, heating energy is introduced into the joining partners by a laser beam in order to melt and plasticize the material of the joining partners in the area of ​​the joining surfaces. In order to enable the weld bead to melt using laser welding, the laser beam is directed against the weld bead that was created in the first step of the welding process by pressure welding. Since the laser beam applies its melting energy largely in a point-like manner to the weld bead, the laser beam must be moved relative to the weld bead. This can be achieved by actively guiding the laser beam around the weld bead when the joining partners are stationary. For example, the laser beam can be guided around the weld bead by a robot. Alternatively, the laser beam can be stationary.The joining partners must then be moved, especially rotated, so that the entire weld bead can be guided past the laser beam. This can be advantageously achieved by rotating the joining partners joined using the pressure welding process during clamping within the pressure welding machine, and by integrating the laser welding device into the pressure welding machine as a component.

[0057] In another further development, gas shielded welding can be carried out as a fusion welding process. Since here too a so-called gas shielded welding gun applies the melting energy largely in a point-like manner to the weld bead, the gas shielded welding gun must be moved relative to the weld bead. This can be achieved by actively guiding the gas shielded welding gun around the weld bead when the joining partners are stationary. For example, the gas shielded welding gun can be guided around the weld bead by a robot. Alternatively, the gas shielded welding gun can be stationary. In this case too the joining partners must be moved, in particular rotated, so that the entire weld bead can be guided past the gas shielded welding gun.This can be achieved in an advantageous manner by rotating the joining partners joined in the pressure welding process during clamping within the pressure welding machine and by integrating the inert gas welding gun as a component of the pressure welding machine.

[0058] In an alternative further development, TIG welding can be carried out as a fusion welding process.

[0059] TIG welding, or tungsten inert gas welding, is similar to gas shielded arc welding, except that the electrode remains in place rather than burning away. The melting point of the tungsten electrode is higher than the melting point of the two joining partners. This TIG welding process is particularly suitable for remelting the weld bead, as no filler material is added from the electrode. This makes it particularly advantageous to flatten and / or level the protrusion formed by the protruding weld bead.

[0060] In a further development, plasma welding may also be used as a fusion welding process. In another further development, electron beam welding may also be used as a fusion welding process.

[0061] Electron beam welding is similar to laser welding with the difference that no laser beam is applied to the welding bead, but an electron beam.

[0062] In order to enable the weld bead to be melted using electron beam welding, the electron beam is directed against the weld bead that was created by pressure welding in the first step of the welding process. Since the electron beam applies its melting energy largely in a point-like manner to the weld bead, the electron beam must be moved relative to the weld bead. This can be achieved by actively guiding the electron beam around the weld bead when the joining partners are stationary. For example, the electron beam can be guided around the weld bead by a robot. Alternatively, the electron beam can be stationary. In this case, the joining partners must be moved, in particular rotated, so that the entire weld bead can be guided past the electron beam.This can be achieved in an advantageous manner by rotating the joining partners joined using the pressure welding process during clamping within the pressure welding machine and by integrating the electron beam welding device into the pressure welding machine as a component.

[0063] The object is also achieved by a welding machine having first devices which are designed to carry out a pressure welding process within the welding machine, and having second devices for carrying out a fusion welding process within the welding machine, as well as having a machine control which is designed and configured to automatically control the first devices and the second devices and to carry out a welding process according to one of the described embodiments.

[0064] Specific embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures. Regardless of the specific context in which they are mentioned, specific features of these exemplary embodiments may, if appropriate, also represent general features of the invention when considered individually or in further combinations.

[0065] It shows :

[0066] Fig. 1 is a flow chart of the steps in the basic inventive

[0067] Procedure,

[0068] Fig. 2 is a schematic representation of an exemplary welding arrangement for carrying out a

[0069] Friction welding process,

[0070] Fig. 3 is an enlarged partial sectional view of the welding arrangement according to Fig. 2 in the area of ​​the joining point of a first joining part and a second joining part with unprocessed

[0071] Welding bead, Fig. 4 is a schematic representation of an exemplary welding arrangement for carrying out a

[0072] resistance welding process,

[0073] Fig. 5 is an enlarged partial sectional view of the welding arrangement according to Fig. 4 in the region of the joining point of a first joining part and a second joining part with a welding bead reworked by the step of the fusion welding process,

[0074] Fig. 6 is a schematic representation of an exemplary welding arrangement for carrying out an MBP-

[0075] welding process,

[0076] Fig. 7 is an enlarged partial sectional view of the welding arrangement according to Fig. 6 in the region of the joining point of a first joining part and a second joining part with a welding bead reworked by the step of the melt welding process, and

[0077] Fig. 8 is a perspective view of an exemplary welding machine in the design of a friction welding machine. In Fig. 1, the welding method according to the invention is shown in

[0078] Schematically shown in the form of a flow chart with the steps S 1 and S2.

[0079] In the basic welding process, in the first step S 1 a first joining part 1 is joined to a second joining part 2 by means of a pressure welding process, in which after the joining a welding bead 4 projecting beyond the surface 3 of the joined first joining part 1 and second joining part 2 is formed at the edge of the joint 5 of the first joining part 1 and the second joining part 2.

[0080] In the basic welding process, in the following second step S2, the welding bead 4 is subsequently melted by means of a melt welding process in such a way that the elevation formed by the projecting welding bead 4 is flattened and / or leveled out.

[0081] According to step S1.1, the pressure welding process can be a friction welding process. As an alternative to a friction welding process, a resistance welding process can be carried out as the pressure welding process in a modified step S1.2. As an alternative to a friction welding process and a resistance welding process, an MBP welding process can be carried out as the pressure welding process in a modified further step S1.3.

[0082] According to step S2.1, the subsequent fusion welding process can be laser welding. As an alternative to laser welding, in a modified step S2.2, gas shielded welding can be carried out as the fusion welding process. As an alternative to laser welding or gas shielded welding, in a modified further step S2.3, TIG welding can be carried out as the fusion welding process. Again as an alternative to laser welding, gas shielded welding, or TIG welding, electron beam welding can be carried out in a modified further step S2.4.

[0083] Fig. 2 shows a schematic representation of a first basic embodiment in the form of a friction welding process.

[0084] In various first variants of the first basic embodiment, the friction welding process can be carried out according to a welding process from the group comprising linear friction welding, friction stir welding, rotary friction welding and orbital friction welding.

[0085] According to the invention, a distinction must be made between the pressure weld seam 10 created in the pressure welding process on the contact surfaces of the parts 1 and 2 to be joined and the welding bead 4. The pressure weld seam 10 and the welding bead 4 are therefore shown in Fig. 3, Fig. 5 and Fig. 7 with different hatching, even if under real conditions they are formed from the same molten, plasticized material of the two parts 1 and 2. The pressure weld seam 10 extends over the entire contact surface between the first part 1 and the second part 2.In contrast, the welding bead 4 is formed by molten and re-solidified material of the first joining part 1 and / or the second joining part 2, which in the molten state pushes out of the joint gap from the area of ​​the entire contact surface between the first joining part 1 and the second joining part 2 due to the pressing process (arrows PI) during pressure welding, namely beyond the surface 3 of the first joining part 1 and / or the second joining part 2. The welding bead 4 is therefore the part of the material that swells out of the joint gap during pressure welding.

[0086] In the case of rotationally symmetrical joining parts 1 and 2, such as shafts, pipes or cylinder rods, a circular ring-shaped welding bead 4 can result. Such a circular ring-shaped welding bead 4 can best be produced in the second step of the method, after which the welding bead 4, which has an original shape according to Fig. 3 after pressure welding and before remelting by means of the fusion welding process, is melted by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead 4 is flattened and / or leveled out, as is the case, for example, in Fig. 5 and Fig. 7 is indicated, in that the joining parts 1 and 2 joined in the first step S 1 of the process by means of the pressure welding process remain in the respective clamping 5 and 6 of the pressure welding machine 7 ( Fig . 8 ) and the joining parts 1 and 2 this

[0087] Clamping can be rotated, as indicated by the arrow PI in Fig. 2, so that the circular welding bead 4 is guided in a rotating manner along a fixed fusion welding device 8, whereby the welding bead 4 is flattened and / or equalized over the circumference of the joined parts 1 and 2.

[0088] As an alternative to a stationary fusion welding device 8, the fusion welding device 8 can optionally also be movably mounted, so that a processing tip 9 of the fusion welding device 8 can be moved along the welding bead 4, in particular can be moved along automatically. The processing tip 9 of the fusion welding device 8 can be movably mounted, regardless of whether the joined parts 1 and 2 are rotatably mounted in the welding machine 7 or are fixedly arranged in the welding machine 7, in order to move the processing tip 9 of the fusion welding device 8 along the welding bead 4, in particular to move it automatically.

[0089] In particular, in pressure welding processes such as MBP welding or MagnetArc welding and friction welding, a particularly circular ring-shaped welding bead 4 is created, which can be at least flattened and / or leveled or even completely removed or eliminated by means of the process according to the invention.

[0090] Fig. 4 shows a schematic representation of a second basic embodiment in the form of a resistance welding process.

[0091] In various second variants of the second basic embodiment, the resistance welding process can be carried out according to a welding process from the group comprising resistance butt welding, pressure butt welding and flash butt welding.

[0092] During the resistance welding process, as indicated in Fig. 4, the first joining part 1 and the second joining part 2 are pressed against one another statically, i.e. without relative movement transverse to the pressing direction, with the joining surfaces of both joining parts 1 and 2 lying opposite one another, perpendicular to the joining surfaces which form the joint, as indicated by the arrows PI. At the same time, electrical energy is conducted from one joining part 1 to the other joining part 2 across the joint. This is indicated by the electrical contacts 11 and the current flow lines 12 in Fig. 4. The material of the two joining partners heats up at the joint, i.e. of the first joining part 1 and the second joining part 2 , due to the Joule current heat which is introduced into the joining partners by the electrical energy .The method according to the invention is particularly useful when used in a resistance welding process in which the joining partners are pressed against one another with contact force, i.e. contact pressure. Here, too, plasticized material of the joining partners is forced out of the joining gap due to the contact force, and the welding bead 4 is formed. Here, too, removal of this welding bead 4, for example by a known turning process using a turning tool in the machine, is not easily possible, especially when the joining parts do not have a rotationally symmetrical shape.On the other hand, with the welding method according to the invention, such a welding bead 4 which may be non-rotationally symmetrical and which is produced during resistance welding can be easily removed by remelting the welding bead 4 by means of a melt welding process in such a way that the elevation formed by the projecting welding bead 4 is flattened and / or leveled out or even completely eliminated by the melt welding, as is shown in Fig. 5.

[0093] Fig. 4 shows a schematic representation of a third basic embodiment in the form of an MBP welding process.

[0094] In the MBP welding process, as indicated in Fig. 6, the two electrically conductive joining partners, i.e. the first joining part 1 and the second joining part 2, are brought into contact at their joining surfaces so that electrical energy can be conducted across the joining surfaces. The two joining partners are then moved away from each other and separated, as indicated by the double arrows P3, so that a gap forms between the two joining partners, across which gap an arc 13 is created due to the continued current flow. By means of an additional magnetic field the arc 13 can be set in motion so that it moves along the joining surfaces and evenly heats the material of the two joining partners in the vicinity of the joining surfaces until it melts and plasticizes.The two joining partners are then pressed against each other with pressure and both the current flow and the magnetic field are switched off. This also forms the welding bead 4. Here too, removal of this welding bead 4, for example by a conventional turning process using a turning tool in the machine, is not easy, especially when the parts to be joined do not have a rotationally symmetrical shape. On the other hand, with the MBP welding process, such a possibly non-rotationally symmetrical welding bead 4 can be easily removed by remelting the welding bead 4 using a fusion welding process in such a way that the elevation formed by the protruding welding bead 4 is flattened and / or leveled out or even completely eliminated by the fusion welding.

[0095] In Fig. 3, Fig. 5 and Fig. 7 the processing tip 9 of the fusion welding device 8 is shown only schematically and abstractly. In a first development the processing tip 9 of the fusion welding device 8 can be a laser welding tip. In a second development the processing tip 9 of the fusion welding device 8 can be a gas-shielded welding tip. In a third development the processing tip 9 of the fusion welding device 8 can be a TIG welding tip. In a fourth development the processing tip 9 of the fusion welding device 8 can be an electron beam welding tip.

[0096] In Fig. 8, a welding machine 7 is shown, comprising first devices 14 which are designed to carry out a pressure welding process within the welding machine 7, and comprising second devices 15 for carrying out a fusion welding process within the welding machine 7, as well as comprising a machine control 16 which is designed and configured to automatically control the first devices 14 and the second devices 15 and in doing so to carry out a combined welding process with the steps S1 and S2 according to one of the described embodiments.

Claims

Patent claims 1. Welding process comprising the steps of: - joining a first joining part (1) to a second joining part (2) by means of a pressure welding process, in which, after joining, a welding bead (4) projecting beyond the surface (3) of the joined first joining part (1) and second joining part (2) is formed at the edge of the joint between the first joining part (1) and the second joining part (2), - subsequent remelting of the welding bead (4) by means of a fusion welding process in such a way that the elevation formed by the projecting welding bead (4) is flattened and / or levelled.

2. Welding method according to claim 1, characterized in that a friction welding method is carried out as the pressure welding method.

3. Welding method according to claim 2, characterized in that the friction welding method is carried out according to a welding method from the group comprising linear friction welding, friction stir welding, rotary friction welding and orbital friction welding.

4. Welding method according to claim 1, characterized in that a resistance welding method is carried out as the pressure welding method.

5. Welding method according to claim 4, characterized in that the resistance welding method is carried out according to a welding method from the group comprising resistance butt welding, pressure butt welding and flash butt welding.

6. Welding method according to claim 1, characterized in that an MBP welding method is carried out as the pressure welding method.

7. Welding method according to one of claims 1 to 6, characterized in that laser welding is carried out as the fusion welding method.

8. Welding method according to one of claims 1 to 6, characterized in that the fusion welding method is carried out by inert gas welding.

9. Welding method according to one of claims 1 to 6, characterized in that TIG welding is carried out as the fusion welding method.

10. Welding method according to one of claims 1 to 6, characterized in that electron beam welding is carried out as the fusion welding method.

11. Welding machine, comprising first devices (14) which are designed to carry out a pressure welding process within the welding machine (7), and comprising second devices (15) for carrying out a fusion welding process within the welding machine (7) and comprising a Machine control (16), which is configured and arranged to automatically control the first devices (14) and the second devices (15) and to carry out a welding process according to one of claims 1 to 10.

Images