DE102019115531A1 - Coaxial powder nozzle tip module for surface treatment of a workpiece - Google Patents

Abstract

The invention relates to a coaxial powder nozzle tip module for a coaxial powder nozzle for surface treatment of a workpiece, in particular for surface treatment of a workpiece with a laser beam. The invention also relates to the coaxial powder nozzle with the coaxial powder nozzle tip module. A coaxial powder nozzle according to the invention has a coaxial powder nozzle tip module and a coaxial powder nozzle base body, the coaxial powder nozzle tip module being arranged on the side of the coaxial powder nozzle base body facing the workpiece surface to be processed. The inventive coaxial powder nozzle tip module has an inner part and an outer part and is suitable for workpiece surface machining by means of laser radiation. Between the inner part and the outer part there is an annular gap for a powder gas mixture to flow through, the annular gap being arranged coaxially to the axis of propagation of the laser radiation. The coaxial powder nozzle tip module is characterized in that it has a quasi-monolithic structure.

Description

The invention relates to a coaxial powder nozzle tip module for a coaxial powder nozzle for surface treatment of a workpiece, in particular for surface treatment of a workpiece with a laser beam. The invention also relates to the coaxial powder nozzle with the coaxial powder nozzle tip module.

The term surface processing is to be understood as broadly as possible and includes, for example, the processes of dispersing, alloying, coating and additive manufacturing using laser radiation (also referred to as laser deposition welding or laser generation). These processes are used for surface treatment, repair and additive manufacturing of components with filler materials. A laser beam is used to create a molten bath on the surface of a component, into which a solid or already melted, powdery filler material is injected via a powder nozzle by means of conveying gas. Moving the component relative to the laser beam creates a layer on the component surface that is fused with the base material via the connection zone. In addition, a heat-affected zone is created in the base material. The powder feed plays an important role in this process. A distinction is essentially made between three ways of adding the powder. The first option is the side powder feed, in which the powder is injected into the weld pool from only one side at a certain angle. In the second option, the powder is injected through several partial beams that are positioned around the laser beam. In addition, the coaxial powder feed is also known, in which the powder is injected into the molten bath in a ring shape at a certain angle. The coaxial powder nozzle systems have the advantage over the side systems that the processing result in the plane is less direction-dependent. This means that 3-D components can also be manufactured using additive manufacturing. With the coaxial powder nozzle systems, significantly higher powder efficiencies can be achieved than with the side powder feed systems. The powder efficiency indicates the ratio of the amount of powder made available to the molten bath to the amount of powder applied.

• Erstens, indem mittels einer Pulverzufuhr einem Schmelzbad festes Pulver zugeführt wird. Das Schmelzbad wird durch Einstrahlung eines Laserstrahls im flüssigen Zustand gehalten. Festes Pulver trifft in dem Bereich des Schmelzbades ein und wird dort durch den Laser aufgeschmolzen. Wird nun das Bauteil gegenüber dem Laser und der Pulverzufuhr bewegt, so bewegt sich das Schmelzbad aus dem Einflussbereich des Lasers heraus und erstarrt. Ein Teil der eingestrahlten Laserenergie wird aufgewendet, um den Grundwerkstoff aufzuschmelzen und dadurch eine schmelzmetallurgische Verbindung zwischen dem Grundwerkstoff und dem Zusatzwerkstoff herzustellen. Hierdurch entsteht auch eine Wärmeeinflusszone. Abhängig von der Leistung des Lasers findet daher eine Durchmischung von Zusatzwerkstoff und Bauteilwerkstoff statt. Mit dem beschriebenen Verfahren lassen sich Prozessgeschwindigkeiten, d. h. Vorschubgeschwindigkeiten des Bauteils gegenüber dem Laserstrahl, zwischen typischerweise 0,2 m/min und 2 m/min erreichen. Die höchsten bisher erreichten Prozessgeschwindigkeiten liegen im Bereich bis zu 20 m/min.

In the prior art, two method variants for producing a layer from the filler material are known:

• Firstly, by feeding solid powder into a molten bath by means of a powder feeder. The weld pool is kept in a liquid state by irradiating a laser beam. Solid powder arrives in the area of the melt pool and is melted there by the laser. If the component is now moved in relation to the laser and the powder feed, the weld pool moves out of the area of influence of the laser and solidifies. Part of the laser energy radiated in is used to melt the base material and thereby create a metallurgical bond between the base material and the filler material. This also creates a heat-affected zone. Depending on the power of the laser, the filler material and component material are mixed. With the method described, process speeds, ie feed speeds of the component with respect to the laser beam, between typically 0.2 m / min and 2 m / min can be achieved. The highest process speeds achieved so far are in the range of up to 20 m / min.

Second, from the German Offenlegungsschrift DE 10 2011 100 456 A1 the so-called EHLA procedure is known. With the EHLA process, a significant increase in the achievable processing speed is achieved by feeding at least one filler material in completely molten form to a molten bath on a surface to be processed. For this purpose, the filler material, which is initially in powder form, is melted by means of a laser beam at a distance greater than zero from the weld pool and then fed to the melt pool in liquid form. The powder can be melted at the specified distance from the weld pool and the base material can be heated and melted using the same laser beam. The laser beam shining on the weld pool also causes the filler metal to melt at the specified distance from the weld pool.

Because the filler material is fed to the weld pool in the liquid state, there is no time to melt the powder particles in the weld pool. This in turn reduces the time required for layer formation, which means that the process speed can be increased significantly. If the powder is injected into the laser beam above the weld pool before it gets into the weld pool, the powder particles' residence time in the laser beam is significantly longer than if the filler metal is only irradiated by the laser beam in the weld pool. A high intensity of the laser radiation shortens the time it takes to melt the particles of the powdered filler metal. The intensity of the laser radiation can be increased on the one hand by increasing the laser power, but on the other hand also by reducing the beam area. The area in which the material is molten is the area in which the intensity of the beam is sufficiently high as a result of the focusing to achieve the To melt powder particles in the time since they entered the laser beam. This area can also extend in front of and / or behind the laser beam focus in the direction of the optical axis of the laser beam. The powdery filler material is preferably injected into the laser beam as a beam. The powder can be transported by a gas jet. It is particularly preferred if the powder jet is focused in a small area. So essentially all powder particles pass through this small area. Such a focusing can be brought about, for example, in that the powder jet is generated by means of a coaxial powder nozzle. A powder jet focused in this way has a conical shape, the tip of the cone being precisely that area on which the powder jet is focused. With such an arrangement, the laser beam and powder gas beam can run coaxially to one another. The particles are then focused above the substrate, the aforementioned powder focus area, where they interact with the laser radiation in order to hit the weld pool from there. The filler material is then liquid.

For a cost-effective implementation of a coaxial powder nozzle, it is advantageous to assemble the nozzle from an inner part and an outer part. It is possible to form a powder chamber and / or an annular gap between the inner part and the outer part. A powder chamber is used to generate a uniform and coaxial powder gas cloud around the laser beam. Due to the two-part design with an inner and an outer part, the size of the chamber and the annular gap can be varied. By changing the size of the chamber and / or the annular gap, the flow of the powder gas mixture or the particle speed can be influenced. The nozzle can therefore be used optimally for different powder gas mixtures and / or different powder grain sizes.

The flow of the powder gas mixture in the chamber and in particular in the annular gap can, under certain circumstances, be sensitive to the geometric dimensions of the annular gap and chamber. If the annular gap and chamber are formed between the inner part and the outer part, the flow can be influenced by fine adjustment of the inner part and the outer part with respect to one another. This fine adjustment is necessary because, according to the prior art, the inner part and the outer part are usually screwed together with a comparatively coarse thread. In addition, minor manufacturing errors in the inner part and outer part can be compensated for. In addition, the fine adjustment of the nozzle and the chamber can be optimized for different flows of powder gas mixtures. The powder gas mixture can have different concentrations of powder in the gas, gas volume flows and different particle sizes of the powder. This also requires an adaptation of the geometric dimensions of the chamber and annular gap by fine adjustment of the distance between the inner part and the outer part of the nozzle. In this way, the proportion that does not contribute to the formation of the layer, the so-called overspray, can also be influenced.

• Die Intensität der Laserstrahlung ist hier definiert als Quotient aus Laserleistung und Querschnittsfläche des Strahls senkrecht zur optischen Achse des Strahls.
• Unter einer koaxialen Pulverdüse wird hier eine Düse zur Zuführung von pulverförmigen Material und eines Laserstrahls verstanden, wobei der Laserstrahl und der Pulverstrahl koaxial zueinander verlaufen, also die gleiche Strahlachse aufweisen.

The following terms are explained:

• The intensity of the laser radiation is defined here as the quotient of the laser power and the cross-sectional area of the beam perpendicular to the optical axis of the beam.
• A coaxial powder nozzle is understood here to mean a nozzle for supplying powdery material and a laser beam, the laser beam and the powder beam running coaxially to one another, that is to say having the same beam axis.

Overspray is understood here as the proportion of the sprayed powder that does not reach the intended location on the workpiece. This powder can escape into the environment or reach the workpiece surface outside of the laser's track width, so that it does not contribute to the desired layer structure.

If the nozzle is damaged due to thermal or mechanical stress, components must be replaced accordingly. There are different solutions for this: either the entire nozzle is replaced or the lower part of the nozzle with the corresponding two conical tips. The second variant is preferred for cost reasons. Generally these nozzle tips are attached via threads. Since the nozzle tips have manufacturing tolerances, are not manufactured in one setting and have play in the thread, the resultant powder gas jet has deviations, for example with regard to the size of the powder jet focus, the symmetry of the powder distribution and / or the overspray. With laser deposition welding, these deviations lead to significant losses in quality (lower degree of powder utilization, insufficiently produced layer thickness). This problem is solved by the fact that the nozzle is laboriously adjusted after changing the tips. This leads to massive interruptions in the process, which is particularly undesirable for series production. Up until now, the two conical nozzle tips were aligned with one another using adjusting screws. The existing play is used to adjust the gap between the two cones so that an even and symmetrical powder jet is created. This adjustment can generally not be carried out by the end user. Other solutions provide for an exchange of the nozzle syringes via thread, whereby the deviations must be accepted in the quality of the powder gas jet. As a high and uniform quality of the powder gas jet is required to carry out the EHLA process, these nozzles are only suitable to a very limited extent for the EHLA process.

The object of the invention is to provide a coaxial powder nozzle tip module for a coaxial powder nozzle for surface treatment of a workpiece, in particular for surface treatment of a workpiece with a laser beam and in particular for laser deposition welding according to the EHLA method, which can be exchanged by the end user, whereby the exchange effort In particular, the necessary interruption in the process is minimized compared to the prior art. This object of the invention is achieved with a coaxial powder nozzle tip module according to independent claim 1. Advantageous further developments of the coaxial powder nozzle tip module emerge from claims 2 to 12. Furthermore, it is the object of the invention to specify a coaxial powder nozzle with the coaxial powder nozzle tip module. This further object is achieved with a coaxial powder nozzle according to claim 13. Advantageous further developments of the coaxial powder nozzle emerge from claims 14 to 15.

The inventive coaxial powder nozzle tip module has an inner part and an outer part and is suitable for workpiece surface machining by means of laser radiation. Between the inner part and the outer part there is an annular gap for a powder gas mixture to flow through, the annular gap being arranged coaxially to the axis of propagation of the laser radiation. The coaxial powder nozzle tip module is characterized in that it has a quasi-monolithic structure.

• Unter einem koaxialen Pulverdüsenspitzenmodul wird bei einem modularen Aufbau einer Pulverdüse zur Zuführung von pulverförmigen Material und eines Laserstrahls zu einer Bearbeitungsstelle auf der Oberfläche eines Werkstücks das Modul verstanden, das die Spitze der Pulverdüse darstellt, wobei der Laserstrahl und der Pulverstrahl koaxial zueinander verlaufen, also die gleiche Strahlachse aufweisen.

Conceptually, the following is explained:

• With a modular structure of a powder nozzle for feeding powdery material and a laser beam to a processing point on the surface of a workpiece, a coaxial powder nozzle tip module is understood to mean the module that represents the tip of the powder nozzle, the laser beam and the powder jet running coaxially to one another, i.e. the have the same beam axis.

The inner part of the coaxial powder nozzle tip module is the part that includes the axis of propagation of the laser radiation as the central axis of the module. The inner part has a bore through which the laser beam can be passed.

The outer part of the coaxial powder nozzle tip module is the part that encloses the inner part of the coaxial powder nozzle tip module.

Workpiece surface machining is understood here to mean machining the surface of a workpiece. The processing can take place in a material-building, material-degrading or neutral manner with regard to material application or removal.

Laser radiation is understood to mean electromagnetic waves, where laser beams are characterized by a combination of high intensity, a very narrow frequency range, sharp focus of the beam and a long coherence length.

The term "end user" is understood here to mean the operator of a workpiece surface processing system which has the coaxial powder nozzle tip module according to the invention. The end user processes workpieces and uses the system as operating equipment and usually has neither the knowledge nor the technical possibilities to set the coaxial powder nozzle tip module.

The term quasi-monolithic is understood here to mean that the coaxial powder nozzle tip module has a preassembled inner and outer cone, an annular gap being formed between the inner and outer cones in which the powder-gas flow can be formed.

The quasi-monolithic powder nozzle tip module is preassembled with corresponding shape and bearing tolerances and can be easily exchanged without the need for manual adjustment. This exchange can be carried out by the end user, since no settings have to be made. The exchange can be carried out in a short time, which also minimizes the necessary interruption in the process. Even after replacing the coaxial powder nozzle tip module, the quality of the powder-gas jet remains the same in terms of powder particle density distribution and uniformity of the powder-gas jet, which also ensures the constant quality of the surface treatment. If a special surface quality of the flow channel of the powder-gas jet is required for the processing of a certain filler material, then a certain surface quality of the flow channel can be set, for example for highly precise focusability of the powder-gas jet, and maintained even after the coaxial powder nozzle tip module has been replaced. Likewise, depending on the application, a desired wear resistance can be set and maintained. In the same way, depending on the filler material, for example depending on the grain size distribution and / or the powder mass flow, an adapted gap dimension can be set and maintained. Furthermore, the quality of the powder-gas jet can be measured with the help of a measuring device, such as that from the German patent DE 10 2011 009 345 B3 is known, described quantitatively and certified.

In an advantageous embodiment, the coaxial powder nozzle tip module has a perforated circle pattern with bores on its back, through which a powder-gas mixture can be guided, the perforated circle pattern being a ring with an inner diameter, formed by the tangent to the bore edges pointing to the axis of propagation of the laser radiation, and an outer diameter, formed by the tangent to the bore edges facing away from the axis of propagation of the laser radiation, and wherein the ring has web surfaces, the web surfaces taking up a maximum of 61% of the total area of the ring. The back of the coaxial powder nozzle tip module is the side opposite the tip and thus the workpiece surface to be machined during operation. The additional material in the form of a powder-gas mixture can be guided through the bores in the direction of the workpiece surface to be machined. The fact that the web surfaces take up a maximum of 61% of the total area of the ring ensures that the additional material is introduced into the coaxial nozzle tip module evenly distributed over the circumference, which means that the additional material can be melted evenly over the circumference and thus the quality of the surface processing is increased. The bores can be designed as countersunk or non-countersunk circular bores or alternatively also as elongated holes, the edges of the elongated holes being able to be broken or unbroken.

In a further advantageous embodiment, the holes forming the hole pattern are conical, their diameter tapers in the direction of the tip. This further increases the quality of the surface treatment.

It has proven to be particularly advantageous if the coaxial powder nozzle tip module has a module chamber encircling the annular gap, the module chamber forming the rear end of the annular gap and being arranged in such a way that the holes forming the hole circle pattern open into it. The distribution of the additional material supplied via the bores of the hole circle pattern is thereby further evened out, whereby the quality of the surface processing is further increased.

In a further advantageous embodiment, the outer part has a flange on its side facing the rear of the coaxial powder nozzle tip module, the inner part also forming a flange on its side facing the rear of the coaxial powder nozzle tip module, and the flange of the outer part and the flange of the inner part in the assembled state pointing towards each other, a spacer ring can be mounted between the two flanges. These can be brought into operative connection with one another via the flanges of the inner and outer parts. The flanges can come to rest on one another in the assembled state. In addition, a spacer ring can also be inserted between the two flanges. Using different strong spacer rings, i.e. Spacer rings that have different material thicknesses in the direction of the axis of propagation of the laser radiation, the annular gap between the inner and outer parts can be adjusted to the size of the gap, i.e. in the height of the gap. The gap size depends on the filler material, in this case mainly on the grain size distribution and the desired powder mass flow. By using spacer rings with different material thicknesses, it is possible to produce coaxial powder nozzle modules that are optimally adapted to the powder mass flow used.

It has also proven to be advantageous if the outer surface of the inner part that forms the annular gap and / or the inner surface of the outer part have a surface hardness of at least 500 HV 0.3. The additional materials used can have an abrasive effect. The abrasive effect is reinforced by the fact that the filler material is in powder form and is passed through the annular gap at high speed by means of a gas flow. Measures for protecting the surface of the surfaces forming the annular gap are therefore advantageous. All known measures for surface protection, such as hardening and / or surface coating, can be considered as measures here.

In an advantageous embodiment, the inner part has a centrally arranged conical bore along the axis of propagation of the laser radiation, the cone tapering towards the tip. A laser beam can be passed through this hole for surface treatment.

It has furthermore proven to be advantageous if the outer part forms a cone tapering towards the tip on its inner surface.

In a further advantageous embodiment, the inner part forms a cone tapering towards the tip on its outer surface.

In one embodiment, the annular gap has a constant gap size from the module chamber to the tip.

In an alternative embodiment, the annular gap tapers from the module chamber to the tip.

Depending on the additional material used, its grain size, the composition of the powder-gas mixture used and the desired volume flow, it may be advantageous to use an annular gap with a constant gap height or with a gap height that changes in the tip direction, ie decreases or increases.

In a further advantageous embodiment, the outer part has an outer cone that tapers from the rear towards the tip. Since the laser beam is focused on the surface of the workpiece to be machined or just above it during operation, the bore can be tapered, which means that the entire coaxial powder nozzle tip module can taper towards its tip, which has advantages in terms of machining narrow geometries and the required dimensions of the coaxial powder nozzle tip module. This is advantageous for the dynamics with which the powder nozzle can be moved.

A coaxial powder nozzle according to the invention is characterized in that it has a coaxial powder nozzle tip module and a coaxial powder nozzle base body, the coaxial powder nozzle tip module being arranged on the side of the coaxial powder nozzle base body facing the workpiece surface to be processed.

In an advantageous embodiment, the powder nozzle base body has at least one powder feed and a circumferential base body chamber, with at least one powder feed opening into the base body chamber and the base body chamber forming a ring coaxial to the axis of propagation of the laser radiation, with at least one peripheral wall of the ring tapering towards the tip, and with the main body chamber forms an open ring surface towards the coaxial powder nozzle tip module, the open ring surface covering the hole circle pattern of the coaxial powder nozzle tip module in the assembled state. The filler material is fed to the coaxial powder nozzle via at least one powder feed and distributed in the circumferential direction over the base body chamber. The filler material passes from the base body chamber through the bores on the hole circle pattern of the coaxial powder nozzle tip module into the annular gap, its distribution in the circumferential direction being further optimized as a result.

It has also proven to be advantageous if the coaxial powder nozzle base body has active cooling. Due to the proximity to the surface of the workpiece to be processed, the powder nozzle becomes warm during operation. The active cooling can be liquid cooling, for example, the cooling liquid flowing in a circumferential channel through the powder nozzle base body and dissipating excess heat.

The coaxial powder nozzle can be used as a combination nozzle for laser deposition welding as well as for pure welding without additional material.

• Unter einem Pulver-Gas-Gemisch wird hier ein Gemisch des zuzuführenden pulverförmigen Zusatzwerkstoffes mit einem Trägergas verstanden. Das Trägergas dient dazu, den Zusatzwerkstoff zu transportieren und ist üblicherweise ein Inertgas, das den Zutritt von Sauerstoff zu dem erhitzten Zusatzwerkstoff beziehungsweise dem Grundwerkstoff verhindert, bzw. minimiert.

Conceptually, it should be explained:

• A powder-gas mixture is understood here to mean a mixture of the powdery filler material to be supplied with a carrier gas. The carrier gas is used to transport the filler material and is usually an inert gas that prevents or minimizes the access of oxygen to the heated filler material or the base material.

A hole circle pattern or hole circle is understood to mean the arrangement of a plurality of bores, the center points of the bores being arranged on a circle in a plane perpendicular to the bore center axes.

A web surface is understood here to mean the surface which a web located between two adjacent bores lying on a hole circle has. The web is formed on the one hand by the edges of the two adjacent bores and on the other hand by the tangent to the bore edges pointing to the axis of propagation of the laser radiation or by the tangent to the bore edges facing away from the axis of propagation of the laser radiation.

The rear side of the coaxial powder nozzle tip module is the side of the coaxial powder nozzle tip module which is opposite the tip and thus the side of the coaxial powder nozzle tip module which is opposite the workpiece surface to be machined during operation. In other words, the rear side of the coaxial powder nozzle tip module is the side of the coaxial powder nozzle tip module facing the powder nozzle base body.

In general, it should be noted that in the context of this document, the indefinite numerals “one”, “two” etc. should not be understood as “exactly one”, “exactly two” etc., but normally as an indefinite article. A statement of the type “one ...”, “two ...” etc. is therefore to be understood as “at least one ...”, “at least two ...” etc., unless it is clear from the respective context shows that only "exactly one", "exactly two", etc. are meant.

In the context of the present patent application, the term “in particular” should always be understood to mean that an optional, preferred feature is introduced with this term. The expression is not to be understood as “and indeed” and not as “namely”.

It should be expressly pointed out that all numerical values given should not be understood as sharp limits, but rather should be able to be exceeded or fallen below on an engineering scale without departing from the aspect of the invention described.

Further advantages, special features and expedient developments of the invention emerge from the subclaims and the following illustration of preferred exemplary embodiments using the figures.

• 1 eine erfindungsgemäße koaxiale Pulverdüse im Schnitt,
• 2 eine erfindungsgemäße koaxiale Pulverdüse in einer Seitenansicht,
• 3 ein erfindungsgemäßes koaxiales Pulverdüsenspitzenmodul in einer Seitenansicht,
• 4 ein erfindungsgemäßes koaxiales Pulverdüsenspitzenmodul in einer Draufsicht.

Show it:

• 1 a coaxial powder nozzle according to the invention in section,
• 2 a coaxial powder nozzle according to the invention in a side view,
• 3 a coaxial powder nozzle tip module according to the invention in a side view,
• 4th a coaxial powder nozzle tip module according to the invention in a plan view.

1 shows a coaxial powder nozzle according to the invention 100 on average. The coaxial powder nozzle 100 has a coaxial powder nozzle tip module 110 and a coaxial powder nozzle body 150 on. The coaxial powder nozzle tip module 110 is with its back 119 on the side of the coaxial powder nozzle body facing the workpiece surface to be processed 150 arranged and has at its opposite end, ie the side facing the workpiece surface to be machined during operation, a point 118 on. Through the entire coaxial powder nozzle 100 runs a conical, extending to the tip 118 tapered bore 114 through which a laser beam can be directed. The powder nozzle body 150 has three powder feeders 153 (only one of these is visible in the section shown) and a circumferential base body chamber 152 on. The powder feeds open into the main body chamber 152 . The body chamber 152 forms one to the axis of propagation 200 the laser radiation coaxial ring. The inner wall of the coaxial ring tapers towards the tip 118 towards. The body chamber 152 forms one to the coaxial powder nozzle tip module 110 towards an open ring surface, wherein the open ring surface is a hole circle pattern 120 of the coaxial powder nozzle tip module 110 covered.

The filler material is fed through the powder feed system 153 the coaxial powder nozzle 100 fed and via the main body chamber 152 distributed in the circumferential direction. From the body chamber 152 the filler material gets through bores 112 on a hole circle pattern 120 (please refer 4th ) of the coaxial powder nozzle tip module 110 into an annular gap 130 that is between an inner part 111 and an outer part 115 of the coaxial powder nozzle tip module 110 is formed. The coaxial powder nozzle body 150 has active cooling in the form of a circumferential cooling channel 151 on, which has a coolant supply 155 and a coolant drain 156 is charged with coolant.

The inner part 111 is with the outer part 115 via a flange 113 of the inner part 111 and a flange 116 of the outer part 115 connected with each other. Furthermore is the coaxial powder nozzle tip module 110 over the flanges 111 , 115 with the coaxial powder nozzle body 150 connected. Between the two flanges 113 , 116 there is a spacer ring 140 . Via different strong spacer rings 140 , ie spacer rings 140 running in the direction of the axis of propagation 200 the laser radiation have different material thicknesses, the between the inner part 111 and the outer part 115 lying annular gap 130 vary in the gap dimension, ie in the height of the gap. The gap size depends on the filler material, in this case mainly on the grain size distribution and the desired powder mass flow.
The coaxial powder nozzle tip module 110 has a quasi-monolithic structure. The quasi-monolithic powder nozzle tip module 110 is preassembled with corresponding shape and bearing tolerances and can be easily exchanged without the need for manual adjustment. This exchange can be carried out by the end user, since no settings have to be made. The exchange can be carried out in a short time, which also minimizes the necessary interruption in the process.

The coaxial powder nozzle tip module 110 has one in the annular gap 130 circumferential module chamber 131 on, with the module chamber 131 the rear end of the annular gap 130 forms. The holes 112 open into the module chamber. In other words, it is the main body chamber 152 about the holes 112 with the module chamber 131 connected.

The outer part 115 points on its inner surface towards the tip 118 tapering cone while the inner part 111 on its outer surface it turns towards the top 118 also has a tapering cone. The annular gap is created through these two cones 130 formed, which is conical to the tip 118 runs tapering and has a constant gap. The cone angles can, however, also be different, so that the gap dimension of the annular gap 118 changed over its height.

In an alternative embodiment, the annular gap tapers from the module chamber to the tip.

The outer part 115 shows you yourself from the back 119 to the top 118 towards tapering outer cone. Since the laser beam is focused on the surface of the workpiece to be machined or just above it during operation, the bore can 114 tapered, creating the entire coaxial powder nozzle tip module 110 to its top 118 can taper conically, which has advantages in terms of machining narrow geometries and in terms of the required mass of the coaxial powder nozzle tip module 110 has the consequence. This is advantageous for the dynamics with which the powder nozzle can be moved.

2 shows a coaxial powder nozzle according to the invention 100 in a side view. In this view are the three powder feeders 153 as well as the coolant supply 155 and the coolant drain 156 to recognize.

3 shows a coaxial powder nozzle tip module according to the invention 110 in a side view. In this view is the spacer ring 114 between the flange 113 of the inner part 111 and the flange 116 of the outer part 115 recognizable.

4th shows a coaxial powder nozzle tip module according to the invention 110 in a plan view of its back 119 . In this view is the flange 113 of the inner part 111 as well as the tapered bore 114 in the middle of the coaxial powder nozzle tip module 110 to recognize. Furthermore, the hole circle pattern is 120 with the holes 112 can be seen through the powder-gas mixture can be conducted. The hole circle pattern 120 forms a ring with an inner diameter, formed by the tangent to the axis of propagation 200 the bore edges pointing towards the laser radiation, and an outer diameter formed by the tangent to that of the axis of propagation 200 the edges of the bore facing away from the laser radiation. This ring has land surfaces between the individual holes 112 on, with the land areas taking up a maximum of 15% of the total area of the ring. Through the holes 112 the additional material can be guided in the form of a powder-gas mixture in the direction of the workpiece surface to be machined. The fact that the web surfaces take up a maximum of 15% of the total area of the ring ensures that the additional material is introduced into the coaxial nozzle tip module evenly distributed over the circumference, which means that the additional material can be melted evenly over the circumference and thus the quality of the surface processing is increased.

The embodiments shown here are only examples and should therefore not be understood as restrictive. Alternative embodiments contemplated by those skilled in the art are equally encompassed by the scope of the present invention.

List of reference symbols

100

Coaxial powder nozzle

110

coaxial powder nozzle tip module

111

inner part

112

drilling

113

flange

114

drilling

115

Outer part

116

flange

118

top

119

back

120

Hole circle pattern

130

Annular gap

131

Module chamber

140

Spacer ring

150

coaxial powder nozzle body

151

Cooling duct

152

Main body chamber

153

Powder feed

155

Coolant supply

156

Coolant discharge

200

Axis of propagation of the laser radiation

QUOTES INCLUDED IN THE DESCRIPTION

This list of the 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.

Patent literature cited

• DE 102011100456 A1 [0004]
• DE 102011009345 B3 [0020]

Claims (15)

Coaxial powder nozzle tip module (110) for workpiece surface processing by means of laser radiation, which has a tip (118) facing the workpiece surface to be processed and a rear side (119) opposite the tip (118) and an inner part (111) and an outer part (115) with an annular gap (130) between the inner part (111) and the outer part (115) for a powder gas mixture to flow through, the annular gap (130) being arranged coaxially to the axis of propagation (200) of the laser radiation, characterized in that the coaxial powder nozzle tip module (110) has a quasi-monolithic structure is. Coaxial powder nozzle tip module (110) according to Claim 1 , characterized in that the coaxial powder nozzle tip module (110) on its rear side (119) has a hole circle pattern (120) with bores (112) through which a powder-gas mixture can be guided, the hole circle pattern (120) having a ring with a The inner diameter, formed by the tangent to the hole edges pointing to the axis of propagation of the laser radiation (200), and an outer diameter, formed by the tangent to the hole edges facing away from the axis of propagation of the laser radiation (200), and the ring having web surfaces, the web surfaces at a maximum Occupy 61% of the total area of the ring. Coaxial powder nozzle tip module (110) according to Claim 2 , characterized in that the holes (112) forming the hole pattern (120) are conical, their diameter tapers in the direction of the tip (118). Coaxial powder nozzle tip module (110) according to one of the Claims 2 or 3 , characterized in that the coaxial powder nozzle tip module (110) has a module chamber (131) running around the annular gap (130), the module chamber (131) forming the rear end of the annular gap (130) and being arranged such that the hole circle pattern ( 120) forming bores (112) open into it. Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the outer part (115) has a flange (116) on its side facing the rear side (119) of the coaxial powder nozzle tip module (110), the inner part (111) also having its side facing the rear side (119) of the coaxial powder nozzle tip module (110) forms a flange (113), and the flange (116) of the outer part (115) and the flange (113) of the inner part (111) face one another in the assembled state , a spacer ring (140) being mountable between the two flanges (113, 116). Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the outer surface of the inner part (111) forming the annular gap (130) and / or the inner surface of the outer part (115) has a surface hardness of at least 500 HV0.3. Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the inner part (111) has a centrally arranged conical bore (114) along the axis of propagation (200) of the laser radiation, the cone tapering towards the tip (118). Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the outer part (115) forms a cone on its inner surface which tapers towards the tip (118). Coaxial powder nozzle tip module (110) according to Claim 8 , characterized in that the inner part (111) forms a cone which tapers towards the tip (118) on its outer surface. Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the annular gap (130) has a constant gap dimension from the module chamber (131) to the tip (118). Coaxial powder nozzle tip module (110) according to one of the Claims 1 to 9 , characterized in that the annular gap (130) changes from the module chamber (131) to the tip (118). Coaxial powder nozzle tip module (110) according to one of the preceding claims, characterized in that the outer part (115) has an outer cone which tapers from the rear side (119) towards the tip (118). Coaxial powder nozzle (100), characterized in that the coaxial powder nozzle (100) has a coaxial powder nozzle tip module (110) according to one of the preceding claims and a coaxial powder nozzle base body (150), the coaxial powder nozzle tip module (110) facing the workpiece surface to be processed Side of the coaxial powder nozzle base body (150) is arranged. Coaxial powder nozzle (100) according to Claim 13 , characterized in that the coaxial powder nozzle main body (150) has at least one powder feed (153) and one circumferential Base body chamber (152), at least one powder feed (153) opening into the base body chamber (152) and the base body chamber (152) forming a ring coaxial to the axis of propagation (200) of the laser radiation, with at least one peripheral wall of the ring conical to the tip (118) The main body chamber (152) forms an open ring surface towards the coaxial powder nozzle tip module (110), the open ring surface covering the hole circle pattern (120) of the coaxial powder nozzle tip module (110) in the assembled state. Coaxial powder nozzle (100) according to one of the Claims 13 or 14th , characterized in that the coaxial powder nozzle body (150) has an active cooling.

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