DE102022123555A1 - Work spindle for a deposition welding machine for coating a rotational workpiece, as well as a deposition welding machine for coating a rotational workpiece - Google Patents

Abstract

The invention relates to a work spindle (1) for a deposition welding machine (2) for coating a rotating workpiece (3, 4), having at least the following components: a spindle shaft (5) with a spindle axis (6), which is connected to a workpiece holder (7, 8) can be connected or connected to accommodate a rotating workpiece (3,4) and can be rotated about the spindle axis (6); - a bearing device (9) comprising at least one radial bearing (10) for supporting the spindle shaft (6) rotatable about the spindle axis (6). 5); and- a guide device (11) for guiding an actively temperable fluid, by means of which at least the radial bearing (10) of the bearing device (9) can be actively tempered. The work spindle (1) is primarily characterized in that the guide device (11) is fluidly connected to a workpiece holder (7,8) during use, so that a rotating workpiece (3,4) held in the workpiece holder (7,8) is transferred the guide device (11) of the work spindle (1) can be actively tempered. The invention further relates to a deposition welding machine for coating a rotating workpiece. With the work spindle or deposition welding machine proposed here, effects due to the temperature dependency in storage can be eliminated during operation.

Description

The invention relates to a work spindle for a deposition welding machine for coating a rotational workpiece, a deposition welding machine for coating a rotational workpiece, and a method with such a deposition welding machine for preheating a rotational workpiece for deposition welding.

It was found that with a build-up welding machine, unlike other processing machines, such as a milling machine or similar, due to the high process temperatures required during build-up welding, a significant heat input occurs not only into the workpiece itself, but also into the components of the machine tool. For increasingly high process speeds, for example with extreme high-speed laser deposition welding [EHLA], ever higher (laser) welding energies are required. This brings with it a variety of problems and the issue of heating of the spindle axis is addressed here.

Proceeding from this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features according to the invention result from the independent claims, to which advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically sensible manner, for which the explanations from the following description and features from the figures, which include additional embodiments of the invention, can also be consulted.

• - eine Spindelwelle mit einer Spindelachse, welche mit einer Werkstückaufnahme zum Aufnehmen eines Rotationswerkstücks verbindbar oder verbunden ist und um die Spindelachse rotierbar ist;
• - eine Lagereinrichtung umfassend zumindest ein Radiallager zum um die Spindelachse rotierbaren Abstützen der Spindelwelle; und
• - eine Leiteinrichtung zum Leiten eines aktiv temperierbaren Fluids, mittels welcher zumindest das Radiallager der Lagereinrichtung aktiv temperierbar ist.

The invention relates to a work spindle for a deposition welding machine for coating a rotary workpiece, having at least the following components:

• - a spindle shaft with a spindle axis, which can be connected or is connected to a workpiece holder for receiving a rotating workpiece and can be rotated about the spindle axis;
• - a bearing device comprising at least one radial bearing for supporting the spindle shaft so that it can rotate about the spindle axis; and
• - a guide device for guiding an actively temperable fluid, by means of which at least the radial bearing of the bearing device can be actively tempered.

The work spindle is primarily characterized in that the guide device is fluidly connected to a workpiece holder when in use, so that a rotary workpiece held in the workpiece holder can be actively tempered via the guide device of the work spindle.

In the following, reference is made to the spindle axis mentioned if the axial direction, radial direction or circumferential direction and corresponding terms are used without explicitly stating otherwise. Ordinal numbers used in the preceding and following descriptions, unless explicitly stated to the contrary, only serve to clearly distinguish them and do not reflect the order or ranking of the designated components. An ordinal number greater than one does not mean that another such component must necessarily be present.

A work spindle is proposed here, which is set up for a build-up welding machine, but is also suitable for other machine tools for machining a workpiece or for a measuring device. The work spindle is particularly preferred for a deposition welding machine for extremely high-speed laser deposition welding [EHLA], in which laser energies above 12 kW [twelve kilowatts] and up to 20 KW and more are used.

The work spindle comprises a spindle shaft which can be connected or is connected to a workpiece holder and can be rotated about a spindle axis. The workpiece holder can be permanently connected to an associated spindle shaft or, depending on the position, to a spindle shaft (preferably usable together with another workpiece holder). By means of the spindle shaft of the work spindle, a torque from a drive machine can be transferred to the (respective) workpiece holder and thus to the recorded rotating workpiece.

For example, the workpiece holder is an (almost) rotationally symmetrical component (such as a brake disc or a piston, for example for a pneumatic or hydraulic system). In one embodiment, the workpiece holder is designed, for example, as a chuck. The spindle shaft is usually connected to the workpiece holder as two separate components, alternatively formed in one piece with at least part of the workpiece holder.

Furthermore, the work spindle comprises a bearing device in which at least one radial bearing, for example two or more radial bearings, preferably as a fixed-loose bearing arrangement and / or as a preloaded bearing (for example in a so-called O-arrangement for the widest possible Support width) and at the same time an axial bearing component. Alternatively or additionally, a separate thrust bearing is provided. The bearing device is set up to provide suitable support for the spindle shaft and, if necessary, directly for the (respective) workpiece holder, so that process forces can be absorbed during design-based production while maintaining the required high level of precision.

In one embodiment (for example as a hydrostatic bearing) of the bearing device, the individual hydrostatic elements (the pockets and bearing surfaces of the hydrostatic bearings) can be functionally assigned to an axis, but are not necessarily formed as a structural unit. For example, a plurality of pockets and bearing surfaces are provided which are aligned radially to the spindle axis, i.e. form a tangential surface or a cylinder jacket (section). These can collectively be referred to as radial bearings. Pockets and bearing surfaces that are set up for axial support, i.e. in a plane to which the spindle axis is normally aligned, can be referred to as axial bearings.

In the case of a bearing device with roller bearings, the design is, for example, conventional, with in one or the other application case at least one of the bearing rings being formed in one piece with an element of the work spindle, for example with an outer housing and/or with the spindle shaft.

Furthermore, a guide device is provided with which an actively temperature-controlled fluid can be conducted, i.e. a liquid or a gas, which can be brought to a changed, preferably predetermined or controllable, temperature, for example, by a heat exchange device (external to the work spindle).

It should be noted that for a workpiece that is currently being machined, cooling the spindle shaft and/or the radial bearing and possibly another bearing is usually the predominant mode of operation. However, in order to set a uniform temperature level, it is (alternatively or additionally) desirable, in one embodiment, to keep the temperature of the radial bearing (preferably the entire bearing device, particularly preferably also the spindle shaft) at a temperature level that is different from the environment (preferably constant). This enables very small deviations in terms of position and also in terms of friction effects (i.e. resistance) when operating the work spindle. Especially with very thin deposition weld layers (such as those applied in EHLA), it is desirable to eliminate the factors influencing the position of the rotating workpiece as much as possible. This is made possible.

It is proposed here that the guide device is designed in such a way that it can be fluidly connected to the workpiece holder or is connected in use, so that when there is an operational connection between the guide device and the workpiece holder, the workpiece holder or a rotary workpiece received by the workpiece holder can be tempered. The guide device therefore comprises at least one connection that is directed towards the workpiece holder or can be fluidly connected to the workpiece holder. In an advantageous embodiment, the workpiece holder itself comprises a line section or a heat transfer surface (preferably encapsulated from the environment) for absorbing and/or releasing heat, which can be connected to the guide device via the at least one connection or is connected in use.

• - eine Auftragschweißeinrichtung;
• - zumindest eine Werkstückaufnahme zum Aufnehmen eines Rotationswerkstücks, mittels welcher ein aufgenommenes Rotationswerkstück zu der Auftragschweißeinrichtung ausgerichtet und rotierbar haltbar ist;
• - zumindest eine Arbeitsspindel mit einer um eine Spindelachse rotierbare Spindelwelle und mit einer Lagereinrichtung;
• - eine Antriebsmaschine zum Rotieren der Spindelwelle um die Spindelachse;
• - ein Leitungssystem zum Zirkulieren eines aktiv temperierbaren Fluids;
• - eine in dem Leitungssystem angeordnete Wärmetauscheinrichtung zum, mittels Zugeben oder Abgeben von Wärme des Fluids an ein Tauschmittel, aktiven Temperieren des Fluids; und
• - eine in dem Leitungssystem angeordnete Fördereinrichtung zum Erzeugen eines Druckgefälles in dem Leitungssystem und in der Wärmetauscheinrichtung für ein Fördern und aktives Temperieren des Fluids.

wobei die Lagereinrichtung der Arbeitsspindel zumindest ein Radiallager zum um die Spindelachse rotierbaren Abstützen der Spindelwelle umfasst, und wobei die Spindelwelle mit jeweils einer der Werkstückaufnahmen drehmomentübertragend verbindbar oder verbunden ist.According to a further aspect, a deposition welding machine for coating a rotary workpiece is proposed, having at least the following components:

• - a deposition welding device;
• - at least one workpiece holder for holding a rotational workpiece, by means of which a recorded rotational workpiece is aligned with the deposition welding device and can be rotated;
• - at least one work spindle with a spindle shaft that can be rotated about a spindle axis and with a bearing device;
• - a drive machine for rotating the spindle shaft about the spindle axis;
• - a line system for circulating an actively temperature-controlled fluid;
• - a heat exchange device arranged in the line system for actively controlling the temperature of the fluid by adding or releasing heat from the fluid to an exchange medium; and
• - A conveying device arranged in the line system for generating a pressure gradient in the line system and in the heat exchange device for conveying and actively controlling the temperature of the fluid.

wherein the bearing device of the work spindle comprises at least one radial bearing for supporting the spindle shaft rotatable about the spindle axis, and wherein the spindle shaft can be connected or is connected to one of the workpiece holders in a torque-transmitting manner.

The deposition welding machine is characterized in particular by the fact that a guide device is also provided, which is arranged in the line system, by means of which the actively temperature-controlled fluid can be guided for actively temperature control of at least the radial bearing of the bearing device.

The deposition welding machine proposed here is set up to coat a rotational workpiece, which is accommodated in a workpiece holder, on a surface of the rotational workpiece to be coated using a welding filler material using a deposition welding device. The welding filler material is provided, for example, in the form of a wire or a powder. The deposition welding device is set up, for example, for plasma welding, arc welding, laser welding or high-speed flame spraying. In an advantageous embodiment, the deposition welding machine or the deposition welding device is for extremely high-speed laser deposition welding [EHLA], such as from the DE 10 2011 100 456 A1 known, established.

The surface of the rotary workpiece to be coated is flat in an advantageous embodiment; alternatively, the surface has elevations and/or depressions, so that it has a 2.5-D topology. The workpiece holder and/or the deposition welding device is movable, so that a relative advance between the deposition welding device and the workpiece holder and/or an alignment of the deposition welding device relative to the workpiece holder or to the surface of the rotational workpiece to be coated is possible. The workpiece holder can be rotated (around the spindle axis). During build-up welding, the feed in the rotating workpiece is made up of the rotation of the rotating workpiece (around the spindle axis) and a relative radial feed, preferably by moving the build-up welding device. In one embodiment, the deposition welding device and/or the workpiece holder is axially movable, for example to adjust a height, to adapt to a workpiece dimension (for different rotational workpieces) and/or to adapt to the current thickness of the coating.

The build-up welding machine includes a drive machine by means of which the spindle shaft can be driven to rotate about the spindle axis. The workpiece holder can be permanently connected to an associated spindle shaft of the work spindle or, depending on the position, to a spindle shaft (preferably usable together with another workpiece holder). By means of the spindle shaft of the work spindle, a torque from the drive machine can be transferred to the (respective) workpiece holder and thus to the recorded rotating workpiece.

For example, the workpiece holder is an (almost) rotationally symmetrical component (such as a brake disc or a piston, for example for a pneumatic or hydraulic system). In one embodiment, the workpiece holder is designed, for example, as a chuck. The spindle shaft is usually connected to the workpiece holder as two separate components, alternatively formed in one piece with at least part of the workpiece holder.

Furthermore, the work spindle comprises a bearing device in which at least one radial bearing, for example two or more radial bearings, preferably as a fixed-loose bearing arrangement and / or as a preloaded bearing (for example in a so-called O-arrangement for the widest possible support width) and at the same time an axial bearing portion . Alternatively or additionally, a separate thrust bearing is provided. The bearing device is set up to provide suitable support for the spindle shaft and, if necessary, directly for the (respective) workpiece holder, so that process forces can be absorbed during design-based production while maintaining the required high level of precision.

The deposition welding machine comprises a line system for circulating an actively temperature-controlled fluid and a heat exchange device arranged in the line system for actively temperature control of the fluid, the further comprising conveyor device being set up to generate a pressure gradient in the line system and in the heat exchange device for conveying and actively temperature control of the fluid . The conveying device is, for example, a circulation pump or a compressor. The heat exchange device comprises, for example, a heat exchanger, for example for giving off or absorbing heat to or from an environment, for example supported by a fan. The heat exchange device includes, for example, an evaporator and/or condenser for releasing or absorbing heat to or from an environment, for example supported by a fan.

It is proposed here that the deposition welding machine further includes a guide device with which an actively temperature-controlled fluid can be conducted, i.e. a liquid or a gas, which is heated to a changed, preferably predetermined or controllable, temperature, for example by means of the heat exchange device can be brought. By means of the guide device, at least the radial bearing, preferably the entire bearing device, can be tempered. In one embodiment, the guide device is part of the work spindle. Alternatively or additionally, the guide device is part of a machine-side holder for the work spindle.

It should be noted that for a workpiece that is currently being machined, cooling the spindle shaft and/or the radial bearing and possibly another bearing is usually the predominant mode of operation. However, in order to set a uniform temperature level, it is (alternatively or additionally) desirable, in one embodiment, to keep the temperature of the radial bearing (preferably the entire bearing device, particularly preferably also the spindle shaft) at a temperature level that is different from the environment (preferably constant). This enables very small deviations in terms of position and also in terms of friction effects (i.e. resistance) when operating the work spindle. Especially with very thin deposition weld layers (such as those applied in EHLA), it is desirable to eliminate the factors influencing the position of the rotating workpiece as much as possible. This is made possible.

In an advantageous embodiment, the guide device can be fluidly connected to the workpiece holder, so that when there is an operational connection between the guide device and the workpiece holder, the temperature of the workpiece holder or a rotary workpiece held by the workpiece holder can be controlled.

It is further proposed in an advantageous embodiment of the build-up welding machine that the bearing device further comprises an axial bearing for axially fixing the spindle shaft, wherein preferably the axial bearing can also be temperature-controlled by means of the actively temperature-controllable fluid via the guide device.

The spindle shaft is fixed in the axial direction by means of the axial bearing, i.e. the axial bearing is designed as a fixed bearing. Alternatively, axial fixation of the spindle shaft is achieved via an integrated function (for example by means of an angular contact ball bearing or a tapered roller bearing). In one embodiment, for example, the spindle shaft is axially fixed exclusively on one side, i.e. on the other side solely via gravity. Alternatively, the spindle shaft is enclosed on both sides and is therefore axially braced or at least can be braced.

Depending on the embodiment and/or the mode of operation, the axial bearing has a temperature-dependent, variable axial bearing position for the spindle shaft. By controlling the temperature of the axial bearing, any possible deviation is eliminated or significantly reduced.

It is further proposed in an advantageous embodiment of the build-up welding machine that the radial bearing, and preferably the axial bearing according to an embodiment according to the above description, is a hydrostatic bearing with a hydraulic fluid, the hydraulic fluid preferably also being the actively temperature-controllable fluid of the guide device.

In this embodiment, the individual hydrostatic elements, i.e. the pockets and bearing surfaces of the hydrostatic bearing, of the bearing device can be functionally assigned to an axis, but are not necessarily formed as a structural unit. For example, a plurality of pockets and bearing surfaces are provided which are aligned radially to the spindle axis, i.e. form a tangential surface or a cylinder jacket (section). These can collectively be referred to as radial bearings. Pockets and bearing surfaces that are set up for axial support, i.e. in a plane to which the spindle axis is normally aligned, can be referred to as axial bearings.

It is now proposed here that the hydraulic fluid is also the temperature-controlled fluid of the guide device, i.e. the pockets of the hydrostatic bearing are part of the guide device or integrated into the guide device. This allows efficient heat transfer to be achieved. For this purpose, active throttles for the hydraulic fluid are preferably provided in the line system directly at a respective pocket of the hydrostatic bearing. Alternatively or additionally, a change in bearing stiffness as a result of the interaction of the gap size between pockets and bearing surfaces, viscosity of the hydraulic fluid and delivery volume is accepted, preferably within a predetermined control window, taking into account the temperature and at least one of the parameters mentioned as a control input variable.

It is further proposed in an advantageous embodiment of the build-up welding machine that the radial bearing, and preferably the axial bearing according to an embodiment according to the above description, is a rolling bearing with at least one ceramic contact surface, with the actively temperature-controlled fluid preferably flowing through the guide device as a gas stream during operation provided.

In the case of a bearing device with rolling bearings, the design is, for example, conventional, with in one or the other application case at least one of the bearing rings being formed in one piece with an element of the work spindle, for example with an outer housing and/or with the spindle shaft. In one embodiment, a guide device is arranged such that at least one of the bearing rings is in close (preferably direct) contact with a line element or with the fluid for temperature control. In one embodiment, a guide device is alternatively or additionally designed such that a lubricant of the at least one roller bearing is provided by the fluid for temperature control and is exchanged for temperature control (preferably continuously).

For a ceramic rolling bearing, a gaseous fluid is preferably used for temperature control and no lubricant is provided. This means that the rolling bearing can be operated at a high temperature and at the same time requires little maintenance. In a ceramic rolling bearing (as we understand it here), the rolling bodies and/or the bearing surfaces are made of a ceramic material or are provided with a ceramic coating, so that at least one ceramic contact surface is formed. It should be noted that a rolling bearing is, for example, a ball bearing, a cylindrical roller bearing or a tapered roller bearing.

It is further proposed in an advantageous embodiment of the deposition welding machine that a heat absorber device is also included, which is set up to collect waste heat during deposition welding,
wherein the heat absorber device is fluidly connected to the line system and can be tempered by means of the actively temperature-controlled fluid that can be conveyed therein.

Waste heat absorbed in the rotating workpiece or the coating formed on the surface of the workpiece is diffusely radiated, but due to the surface formation, a main direction for radiation is formed normal to the surface to be coated. A main direction is characterized by the fact that most of the thermal radiation is emitted in this direction, preferably more than 20% [twenty percent], particularly preferably at least 50% of the thermal radiation. The term thermal radiation here preferably refers not only to a radiation frequency range which directly leads to the heating of an affected component, but also to those which occur as a result of a phase shift that occurs (with a certain probability or to a certain extent, for example immediately upon impact) (for example as a result of a Refraction) can cause a component that is hit to heat up.

When welding energy is introduced in the form of light, for example with a flame, plasma or laser light, the law of reflection applies, so that the angle of incidence equal to the angle of reflection represents the main direction for radiating the welding energy provided in the form of light. In a preferred embodiment, the surface of the workpiece to be coated is inclined relative to the welding device or to the direction of input of the welding energy, for example by 15° [fifteen degrees from 360°] to 45°, preferably 25°, so that there is a corresponding surface normal (i.e. with an ideally smooth and reflective surface of the same amount) the discharge angle forms as the main direction. It should be noted that the surface is generally not ideally mirror-smooth and, due to scattering effects when welding filler material is provided, in particular as powder, a considerable proportion of the light-shaped welding energy introduced is emitted outside the main direction, for example in a cone shape from the surface to be coated.

It is proposed here that the device has a heat absorber device which is set up to absorb or conduct away part of the waste heat radiated from the surface to be coated from the previously described process. For this purpose, a collecting surface is provided, which is designed (at least in the broadest sense) to absorb the radiated waste heat. This collecting surface is set up in such a way that the smallest possible proportion of the waste heat radiated and radiated into the collecting surface is reflected. In a preferred embodiment, the collecting surface is also set up in such a way that it has a low tendency to release absorbed heat in the form of thermal radiation. Furthermore, a cooling surface is provided which is solidly and thermally connected to the collecting surface and can be actively flowed through with a cooling fluid and is actively flowed through during operation. This cooling surface is supplied by the heat absorbed by the collecting surface. In a preferred embodiment, the cooling surface (in continuous operation) is supplied with more than 50% [fifty percent], preferably at least 80%, of the heat absorbed by the collecting surface. The remaining heat is stored in the component (i.e. the substrate) with the collecting surface or an adjacent component. Preferably, a proportion of the heat that is radiated again is less than the heat stored in the component mentioned with or near the collecting surface. Preferably, the cooling surface is used to dissipate heat stored in the component mentioned directed. Preferably, a portion of the absorbed or reflected thermal radiation that is re-emitted as thermal radiation from the collecting surface is deflected or scattered in such a way that the resulting heat input into a further component, and above all the deposition welding device, is small, preferably negligible.

It is now further proposed here that the heat absorber device is connected to the line system, so that waste heat absorbed by the heat absorber device can be used to control the temperature of at least one component of the storage device. Thus, with the waste heat from a previous process when the storage device cools down, it can be brought (again) to a desired operating temperature or cooling can be prevented.

It is further proposed in an advantageous embodiment of the build-up welding machine that an indexing table is also included, by means of which the workpiece holder can be moved, preferably together with the work spindle, at least into a processing position and into an assembly position,
wherein preferably a plurality of identical workpiece holders are provided, particularly preferably with a work spindle permanently assigned to the respective workpiece holder.

In this embodiment, it is proposed that a further workpiece holder is provided, which can be equipped outside of a position for processing by means of the welding device, or from which a rotary workpiece can be removed outside of said position. For this purpose, the multiple workpiece holders can be moved into the respective position, i.e. at least one processing position for processing and one loading position for removing and inserting a rotary workpiece, by means of a common switching table. It should be noted that in one embodiment additional workpiece holders are provided. The majority of the workpiece holders can be moved together on the common indexing table, so that moving a workpiece holder into the position for machining simultaneously causes another workpiece holder to move out of this position.

It is further proposed in an advantageous embodiment of the deposition welding machine that the deposition welding device is set up for extremely high-speed laser deposition welding.

In this advantageous embodiment, the deposition welding machine or the deposition welding device is for extremely high-speed laser deposition welding [EHLA], such as from the DE 10 2011 100 456 A1 known, set up in which laser energies above 12 kW [twelve kilowatts] and up to 20 KW and more are preferably used.

It is further proposed in an advantageous embodiment of the build-up welding machine that a heat conduction device is also provided in the workpiece holder, which is fluidly connected directly to the conduction device of the work spindle and/or the heat exchange device for temperature control of a received rotary workpiece.

In an advantageous embodiment, the workpiece holder itself comprises a line section or a heat transfer surface (preferably encapsulated from the environment) for absorbing and/or releasing heat, which can be connected to the guide device via the at least one connection or is connected in use.

In an advantageous embodiment, this heat-conducting device is supplied with heat supplied (preferably also collected by the heat absorber device described above) during machining by means of the deposition welding device during a recorded rotational workpiece in the machining position (preferably held by a common indexing table). This waste heat is dissipated by means of the heat conduction device in order to keep the rotary workpiece being processed at a desired temperature or at least to slow down heating. In a particularly advantageous embodiment, the heat conduction device is fluidly connected to the line system with the fluid for temperature control of at least one component of the storage device. In a particularly advantageous embodiment, the heat-conducting device is the only heat source for the operating temperature of the at least one component of the storage device.

In an advantageous embodiment, this heat-conducting device can alternatively or additionally be supplied beforehand during a recorded rotational workpiece outside the machining position (preferably held by a common indexing table) by means of externally supplied heat (preferably that collected by the heat absorber device), for example via the line system with the fluid for temperature control at least one component of the storage facility. In a particularly advantageous embodiment, the heat absorber device is the only heat source for the process heat, which is the heat conduction device of the workpiece holder needed to preheat the rotating workpiece. Reference is hereby made to the above statements regarding the use of the collected heat of the heat absorber device.

1. a. mittels der Wärmeleiteinrichtung Auffangen von Abwärme bei einem Bearbeiten eines in einer ersten Werkstückaufnahme aufgenommenen ersten Rotationswerkstücks in einer Bearbeitungsposition; und
2. b. mittels des aktiv temperierbaren Fluids in dem Leitungssystem Zuführen zumindest eines Teils der aufgefangenen Abwärme zu in die Leiteinrichtung zum aktiven Temperieren zumindest des Radiallagers der Lagereinrichtung und/oder einem in einer zweiten Werkstückaufnahme aufgenommenen zweiten Rotationswerkstück, welches sich außerhalb einer Bearbeitungsposition befindet.

According to a further aspect, a method for preheating a rotational workpiece for deposition welding is proposed, wherein the method can be carried out with a deposition welding machine according to an embodiment according to the above description, comprising the following steps:

1. a. collecting waste heat by means of the heat-conducting device when machining a first rotational workpiece held in a first workpiece holder in a machining position; and
2. b. by means of the actively temperature-controllable fluid in the line system, supplying at least part of the collected waste heat to the guide device for active temperature control of at least the radial bearing of the bearing device and / or a second rotational workpiece accommodated in a second workpiece holder, which is located outside a machining position.

In an alternative embodiment, in an analogous step b. the heat for temperature control of at least one component of the storage device and / or at least one rotating workpiece is supplied exclusively from external sources, for example by means of a heat exchange device. In one embodiment, in step b. both the collected waste heat and (preferably additionally if necessary) supplied from external sources.

• 1: eine Auftragschweißmaschine in einer schematischen Seitenansicht; und
• 2: ein Kraftfahrzeug mit Bremsscheiben in einer schematischen Draufsicht.

The invention described above is explained in detail below against the relevant technical background with reference to the associated drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, although it should be noted that the drawings are not true to size and are not suitable for defining size relationships. It is presented in

• 1 : a cladding welding machine in a schematic side view; and
• 2 : a motor vehicle with brake discs in a schematic top view.

In 1 a build-up welding machine 2 is shown in a schematic side view. The deposition welding machine 2 includes a deposition welding device 12 and a feed device 22, which are set up for coating a (first shown here) rotary workpiece 3. The first rotary workpiece 3 is received by a first workpiece holder 7, the first workpiece holder 7 comprising a heat-conducting device 21. In this exemplary embodiment, a second workpiece holder 8 is arranged next to the first workpiece holder 7, the second workpiece holder 8 being designed analogously to the first workpiece holder 7, i.e. equipped with a heat-conducting device 21 and set up to hold a second rotating workpiece 4. The workpiece holders 7, 8 are arranged here on a common indexing table 20, the indexing table 20 being set up to rotate about a rotation axis 23 on the indexing table side, so that one workpiece holder 7, 8 can be positioned in such a way that the rotary workpiece 3, 4 is received for coating by means of the Deposition welding device 12 and the feed device 22 is arranged. The workpiece holders 7,8 are set up to tilt the rotational workpieces 3,4 along a main direction 24. It should be noted that some components of the build-up welding machine 2 are designated here pars-pro-toto.

The deposition welding device 12 and the feed device 22 are set up for extremely high-speed laser deposition welding [EHLA], with a welding filler material 25 being able to be fed above a surface 26 of the rotation workpiece 3 to be coated by means of the feed device 22. The welding filler material 25 is set up for melting by means of the deposition welding device 12, the deposition welding device 12 being used to introduce welding energy in the form of laser light 27 into the supplied welding filler material 25 above the surface 26 to be coated and into the surface 26 of the (here first) rotary workpiece 3 to be coated is set up. The surface 26 of the rotary workpiece 3 to be coated is flat in this exemplary embodiment; alternatively, the surface 26 has elevations and/or depressions, so that it has a 2.5-D topology. The workpiece holder 7 and/or the build-up welding device 12 is movable, so that a relative feed direction 28 between the build-up welding device 12 and the workpiece holder 7 and/or an alignment of the build-up welding device 12 relative to the workpiece holder 7 or to the surface 26 to be coated is possible. In addition, the two workpiece holders 7, 8 are set up for rotation about a spindle axis 6.

The deposition welding machine 2 also includes a work spindle 1 for each workpiece holder 7.8. Each work spindle 1 in turn includes a spindle shaft 5, which is connected to the respective work piece holder 7,8 can be connected or is connected, and can be rotated about a spindle axis 6. The workpiece holder 7, 8 can be permanently connected to an associated spindle shaft 5 or, depending on the position, to a spindle shaft 5 (preferably usable together with another workpiece holder 8). By means of the spindle shaft 5 of the work spindle 1, a torque of a drive machine 13 can be transferred to the (respective) workpiece holder 7.8 and thus to the recorded rotary workpiece 3.4.

Furthermore, the work spindle 1 comprises a bearing device 9, in which at least one radial position 10 is preferably used as a fixed-loose bearing arrangement or as a prestressed bearing (for example in a so-called O-arrangement for the widest possible support width) and at the same time an axial bearing component. A separate thrust bearing 18 is provided here. The storage device 9 is set up to provide suitable support for the spindle shaft 5 and, if necessary, directly for the (respective) workpiece holder 7, 8, so that process forces can be absorbed during the design-based production while maintaining the required high level of precision. In this exemplary embodiment, the radial bearing 10 and the axial bearing 18 are each designed as a hydrostatic bearing, which can be supplied with lubricant by means of a guide device 11.

Furthermore, it is provided with the guide device 11 that an actively temperature-controlled exchange medium 16 can be conducted, i.e. a liquid or a gas, which can be brought to a changed, preferably predetermined or controllable, temperature, for example, by a heat exchange device 15 (external to the work spindle 1). The guide device 11 is designed in such a way that it can be fluidly connected to the workpiece holder 7.8 or is connected in use, so that when there is an operational connection between the guide device 11 and the workpiece holder 7.8, the workpiece holder 7.8 can be temperature-controlled or one of the workpiece holders 7.8 recorded rotating workpiece 3.4. The guide device 11 therefore comprises at least one connection that is directed towards the workpiece holder 7.8 or can be fluidically connected to the workpiece holder 7.8.

Due to the laser of the deposition welding device 12 used in this exemplary embodiment, the law of reflection applies to the laser light 27, so that the following applies: angle of incidence 29 equals angle of reflection 30. Thus, a main direction 24 represents the direction of radiation of the welding energy provided in the form of light, with a small proportion of scattered light 31 is emitted.

The workpiece holders 7, 8 are designed in this exemplary embodiment in such a way that a recorded rotational workpiece 3 is tilted relative to the earth's gravity field in the position for processing by means of deposition welding. In this exemplary embodiment, the surface 26 of the workpiece to be coated is inclined relative to the deposition welding device 12, for example by 25° here.

It should be noted that the surface 26 to be coated is not ideally mirror-smooth and, due to scattering effects when welding filler material 25 is provided, in particular as powder, a considerable proportion of the welding energy introduced (not just the laser light 27) is emitted outside the main direction 24, for example conical from the surface 26 to be coated.

The tilting of the rotating workpiece 3 is selected such that the emerging laser light 27 strikes a (here purely optional) collecting surface 32 of a heat absorber device 19. It is proposed here that the collecting surface 32 forms a radiation trap, so that a minimum of the input radiation (shown here in simplified form only of the laser light 27) is reflected and this reflected thermal radiation is scattered in such a way that the radiated welding energy heats the heat absorber device 19.

Due to the topology of the surface 26 of the rotating workpiece 3 to be coated, there is usually a scattering of the laser light 27. The scattering cone 33 has an (approximate) Gaussian distribution, so that the majority of the energy is in a cone with the scattering angle 34 of, for example, 15°.

The heat absorber device 19 can be moved in a fixed manner relative to the deposition welding device 12 at least along the feed direction 28 (here purely optionally fixed by means of a connecting arm 35 to the deposition welding device 12 and the feed device 22), so that the heat absorber device 19 or the collecting surface 32 is compared to the surface to be coated 26 of the rotating workpiece 3 can be made smaller.

The heat absorber device 19 comprises a cooling surface 36 arranged on the rear of the collecting surface 32, which can be cooled by means of an exchange medium 16 (here (purely optional) as a liquid within the line system 14) and is also designed as a heat exchange device 15. In this exemplary embodiment, the line system 14 is connected in a thermally conductive manner to the collecting surface 32, the heat-conducting device 21 and the storage device 9.

It is now proposed here that the exchange medium 16, which is temperature-controlled on the cooling surface 36 of the heat absorber device 19, by means of a conveyor device 17 for temperature control of the rotating workpieces 3, 4 and/or the storage devices 9 of the workpiece holders 7, 8 via the heat-conducting devices 21 on the workpiece holders 7,8 or at the storage devices 9 by means of the heat exchange device 15 is used. The conveying device 17 is set up to generate a pressure gradient in the line system 14 and in the heat exchange device 15, so that conveying and active temperature control of the exchange medium 16 can be achieved. The conveying device 17 is, for example, a circulation pump, a throttle or a compressor.

In 2 a motor vehicle 37 with brake discs 38 is shown in a schematic top view. The motor vehicle 37 has four wheels 39, with two wheels 39 being arranged opposite each other on a common wheel axle. In this example, each of the wheels 39 has a brake disc 38, with the wheel 39 and brake disc 38 being connected in a torque-tight manner.

For example, on each of the two axially opposite sides of the brake disc 38 by means of the in 1 cladding machine 2 shown, a finishing layer is applied to the surface 26 of a rotary workpiece 3,4 to be coated. A pair of brake pads 40 is arranged on each of the brake disks 38, the brake pads 40 being firmly connected to the vehicle body. To decelerate the motor vehicle 37, a respective brake pad 40 is pressed (each or individually controlled) against the respective brake disc 38. The braking energy is largely introduced into the respective brake disc 38 as waste heat, which is why the finishing layer is subjected to high temperatures and high shear loads and high pressure. The finishing layer must be able to withstand this load.

With the work spindle or deposition welding machine proposed here, effects due to temperature dependence in storage can be eliminated during operation.

Reference symbol list

1

work spindle

2

Hardfacing welding machine

3

first rotation workpiece

4

second rotating workpiece

5

spindle shaft

6

Spindle axis

7

first workpiece holder

8th

second workpiece holder

9

Storage facility

10

Radial bearing

11

Guidance device

12

Deposition welding device

13

prime mover

14

Piping system

15

Heat exchange device

16

medium of exchange

17

funding facility

18

Thrust bearing

19

Heat absorber device

20

switch table

21

Heat conduction device

22

Feeding device

23

Axis of rotation

24

main direction

25

Welding filler material

26

surface to be coated

27

Laser light

28

feed direction

29

Angle of incidence

30

angle of reflection

31

Stray light

32

Collection area

33

Scatter cone

34

scattering angle

35

connecting arm

36

cooling surface

37

motor vehicle

38

Brake disc

39

wheel

40

Brake pad

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 102011100456 A1 [0018, 0044]

Claims (10)

Work spindle (1) for a deposition welding machine (2) for coating a rotary workpiece (3,4), comprising at least the following components: - a spindle shaft (5) with a spindle axis (6), which has a workpiece holder (7,8) for receiving a rotary workpiece (3,4) can be connected or connected and can be rotated about the spindle axis (6); - a bearing device (9) comprising at least one radial bearing (10) for supporting the spindle shaft (5) so that it can rotate about the spindle axis (6); and - a guide device (11) for guiding an actively temperable fluid, by means of which at least the radial bearing (10) of the bearing device (9) can be actively tempered, characterized in that the guide device (11) is also in use with a workpiece holder (7, 8 ) is fluidly connected, so that a rotating workpiece (3,4) held in the workpiece holder (7,8) can be actively tempered via the guide device (11) of the work spindle (1). Deposition welding machine (2) for coating a rotary workpiece (3,4), having at least the following components: - a deposition welding device (12); - at least one workpiece holder (7,8) for holding a rotary workpiece (3,4), by means of which a received rotary workpiece (3,4) is aligned with the deposition welding device (12) and can be rotatably held; - at least one work spindle (1) with a spindle shaft (5) which can be rotated about a spindle axis (6) and with a bearing device (9); - a drive machine (13) for rotating the spindle shaft (5) about the spindle axis (6); - a line system (14) for circulating an actively temperature-controlled fluid; - a heat exchange device (15) arranged in the line system (14) for actively controlling the temperature of the fluid by adding or releasing heat from the fluid to an exchange medium (16); and - a conveying device (17) arranged in the line system (14) for generating a pressure gradient in the line system (14) and in the heat exchange device (15) for conveying and actively controlling the temperature of the fluid. wherein the bearing device (9) of the work spindle (1) comprises at least one radial bearing (10) for supporting the spindle shaft (5) so that it can rotate about the spindle axis (6), and wherein the spindle shaft (5) each has one of the workpiece holders (7, 8) can be connected or connected in a torque-transmitting manner, characterized in that a guide device (11) is also provided, which is arranged in the line system (14), by means of which the actively temperature-controlled fluid can be conducted for active temperature control of at least the radial bearing (10) of the bearing device (9). is. Build-up welding machine (2). Claim 2 , wherein the bearing device (9) further comprises an axial bearing (18) for axially fixing the spindle shaft (5), wherein preferably the axial bearing (18) can also be tempered by means of the actively temperature-controlled fluid via the guide device (11). Build-up welding machine (2). Claim 2 or Claim 3 , wherein the radial bearing (10), and preferably the axial bearing (18) after Claim 3 , is a hydrostatic bearing with a hydraulic fluid, the hydraulic fluid preferably also being the actively temperature-controllable fluid of the guide device (11). Build-up welding machine (2) according to one of Claim 2 until Claim 4 , wherein the radial bearing (10), and preferably the axial bearing (18) after Claim 3 , is a rolling bearing with at least one ceramic contact surface, wherein during operation the actively temperable fluid is preferably provided as a gas stream via the guide device (11). Build-up welding machine (2) according to one of Claim 2 until Claim 5 , further comprising a heat absorber device (19), which is set up to collect waste heat during deposition welding, wherein the heat absorber device (19) is fluidly connected to the line system (14) and can be tempered by means of the actively temperable fluid that can be conveyed therein. Build-up welding machine (2) according to one of Claim 2 until Claim 6 , further comprising an indexing table (20), by means of which the workpiece holder (7, 8), preferably together with the work spindle (1), can be moved at least into a processing position and into an assembly position, preferably a plurality of identical workpiece holders (7, 8), particularly preferably with a work spindle (1) permanently assigned to the respective workpiece holder (7, 8). Build-up welding machine (2) according to one of Claim 2 until Claim 7 , wherein the deposition welding device (12) is set up for extremely high-speed laser deposition welding. Build-up welding machine (2) according to one of Claim 2 until Claim 8 , whereby a heat-conducting device (21) is also provided in the workpiece holder (7,8), which is used to control the temperature of a recorded rotary workpiece (3,4) directly with the guide device (11). Work spindle (1) and / or the heat exchange device (15) is fluidly connected. Method for preheating a rotary workpiece (4) for deposition welding, the method using a deposition welding machine (2). Claim 9 is executable, comprising the following steps: a. by means of the heat-conducting device (21) collecting waste heat when machining a first rotary workpiece (3) held in a first workpiece holder (7) in a machining position; and b. by means of the actively temperable fluid in the line system (14) supplying at least part of the collected waste heat into the guide device (11) for active temperature control of at least the radial bearing (10) of the bearing device (9) and/or one in a second workpiece holder (8) recorded second rotation workpiece (4), which is located outside a machining position.

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