DE102018112829A1 - Waveguide arrangement of a laser welding system, corresponding laser welding system and associated welding method - Google Patents

Abstract

The present invention relates to a waveguide arrangement. The waveguide assembly includes a waveguide body having an entrance end through which laser light from a laser source enters the waveguide body, and an exit end through which the laser light exits the waveguide body and which is adjacent to two components to be welded together. Furthermore, the waveguide arrangement comprises a heating means, with which at least a first region of the waveguide body adjacent to the outlet end can be heated to a temperature which is above a dew point of the material of at least one of the components to be welded.

Description

Field of the invention

The present invention relates to a waveguide arrangement of a laser welding system, a corresponding laser welding system, the use of a material for at least a first component of the components to be welded with a laser welding system and a laser welding method.

Background of the invention

In all types of welding in which plastic is heated as a material for at least one of the components to be welded together, the plastic, such as a polyamide, outgas and material vapors are formed. These condense on cold surfaces and thereby contaminate the tool required for welding.

In particular, laser beam welding will be considered below. In corresponding laser welding systems, the last element, i. Before the laser light from a laser source strikes the components to be welded, a waveguide is present. In particular, the waveguide has the task of homogenizing the distribution of the laser light, so that the energy of the laser light strikes the components to be welded as uniformly as possible and individual focal points are avoided.

In principle, a distinction is made between two types of waveguide, namely the positive and the negative waveguides. Positive waveguides consist of a body that conducts laser light inside. An example of such a positive waveguide is in DE 10 2004 058 221 A1 described. Negative waveguides are characterized by a channel-shaped cavity coated with a reflective layer, in which the laser light is guided. An example of such a negative waveguide can be found in the DE 11 2007 002 109 T5 ,

Particularly in the case of laser beam welding with a negative waveguide, the vapors produced during the welding of plastic components are particularly critical. This is because the vapors inside the waveguide, i. on the walls of the channel-shaped cavity, knock down. Condensation of the vapors inside the waveguide leads to a negative influence on the transmission of the laser radiation in the waveguide. Therefore, the waveguide no longer works optimally and must be cleaned accordingly. However, the interior of the waveguide is difficult to access for cleaning, so that possible resulting deposits are not easily removed, but require a correspondingly high time and effort.

One solution known in the art for preventing condensation is to blow the interior of the waveguide during welding with air. This procedure is also referred to as air purge.

An example in which an airflow passes through a portion of a negative waveguide is in FIG EP 1 987 944 A1 described. However, the air flow is used here for pressing together the components to be welded together. The corresponding laser transmission welding arrangement for connecting workpieces made of thermoplastic materials comprises a workpiece holder for positioning the workpieces and a processing head into which a laser beam can be coupled in and out, which plasticises the workpieces at their contact surfaces along a welding contour. In the machining head guiding devices for the laser beam are provided. Furthermore, the laser transmission welding arrangement comprises a pressure device for compressing the workpieces during the welding process, wherein the machining head and the workpiece holder are movable relative to each other. The printing device is arranged away from the workpieces and presses the workpieces by applying at least one fluid stream, preferably an air or water stream, to each other and / or against the workpiece holder, so that can be dispensed with individual, adapted to the shape of the workpieces fixtures ,

The object of the present invention is therefore to provide a waveguide arrangement of a laser welding system, in which the condensation of the material vapors of at least one of the components to be welded inside the waveguide is reduced and which is optimized with respect to the known prior art arrangements. It is likewise an object of the present invention to provide a corresponding laser welding system and a laser welding method.

Summary of the Invention

The above object is achieved by a waveguide arrangement of a laser welding system according to independent claim 1, a laser welding system according to independent claim 12, the use of a material for at least a first component according to independent claim 13 and a laser welding method according to independent claim 17. Advantageous embodiments and Further developments result from the following Description, the drawings and the appended claims.

A waveguide assembly of a laser welding system according to the invention comprises a waveguide body having an entrance end through which laser light from a laser source enters the waveguide body during operation, and an exit end through which the laser light leaves the waveguide body during operation and which is adjacent to two components to be welded together during operation and a heating means for heating at least a first portion of the waveguide body adjacent the exit end to a temperature above a dew point of the material of at least one of the two components to be welded together during operation.

For better understanding, the waveguide arrangement according to the invention is now described when used in a laser welding system, in particular a laser welding system for processing components made of plastic, such as a laser transmission welding system. The laser welding system comprises, in addition to the waveguide arrangement, a laser light source and a conductor for the laser light, so that the laser light from the laser light source reaches the entrance end of the waveguide body. The waveguide body itself thus represents along the path of the laser light, the last element of the laser welding system before the laser light strikes the components to be welded together.

During operation of the laser welding system with the waveguide arrangement, the material of at least one of the components is in particular due to the heating of the plastic components. An exemplary component material here is a plastic from the group of polyamides. Due to these outgassing and the associated material vapors is now provided to heat the waveguide body before welding the two components together. This is done via the heating means of the waveguide arrangement. The heating takes place at a temperature which is reliably above the dew point of the material of at least one of the two components to be welded together. In this way, condensation of the vapors or outgassing of the material during welding is reduced or preferably prevented by at least one of the two components. The heating takes place starting from the outlet end, since the waveguide body is usually in direct contact with one of the components, so the material vapors thus come into contact with the waveguide body from the outlet end. Preferably, the waveguide body is heated to a temperature which is above the dew point of the materials or material vapors for both or all components used.

An advantage of this approach is that condensation of the corresponding material vapors is effectively reduced or prevented. Accordingly, the transmission of the laser light in the waveguide body is no longer adversely affected. The solution according to the invention is a structurally simple and cost-effective alternative to air flushing. Since the condensation is preferably prevented altogether, a cleaning cycle of the waveguide body can also be correspondingly increased, which in turn has an advantageous effect on the operating times of the corresponding laser welding system.

In a preferred embodiment, a channel is formed in the waveguide body between the inlet end and the outlet end, through which the laser light runs during operation and on whose side surfaces the laser light is reflected. By these features, the waveguide body is formed as a negative waveguide, so that the temperature required to prevent condensation on the walls of the channel must be achieved. Thus, in this waveguide body is not a solid body, but in the interior of the waveguide body is a coated with a reflective layer channel-shaped cavity exists in which the laser light is guided.

Especially in this embodiment of the waveguide body, the heating of the waveguide body to a temperature that is reliably above the dew point of at least one of the components, a particularly advantageous approach is. In particular, the channel must be cleaned significantly less often due to the heating compared to a waveguide body according to State of the art. In this connection, it is preferable that the waveguide body is made of steel and the channel is coated with gold. However, other thermally conductive materials are preferred for the waveguide body as well as other particularly reflective layers for coating the channel.

Advantageously, the waveguide body is heated over its entire length or the first region is 50% of a length of the waveguide body, preferably 1/3 of the length. The length of the waveguide body is determined by the distance between the entrance end and the exit end along the path that the laser light passes through the waveguide body. With reference to the waveguide body with channel, this also means along the course of the channel.

A selection of the heated length depends in particular on the particular application and thus also on the components to be welded together or their materials. Usually, condensation takes place in a region adjacent to the exit end of the waveguide body. In the case of the channel in the waveguide body, material vapors may flow into the channel opposite the path of the laser light. Therefore, heating of the waveguide body is particularly important in this embodiment, starting at the exit end. In this case, according to a first alternative, the waveguide body is heated so that the channel over its entire length has a temperature which is reliably above the corresponding dew point. In a second alternative, only a portion of the waveguide body is heated beginning at the exit end. This procedure is based on the observation that condensation takes place mainly in the lower half of the waveguide body and in particular in the lower third. The upper half or the upper part of the waveguide body is usually not affected so much. An advantage of this approach is therefore that it particularly efficient and targeted condensation prevents, without requiring a general heating of the waveguide body with the associated costs.

It is furthermore preferred to provide a flow barrier adjacent to the first region at the end of the first region facing the inlet end of the waveguide body, in particular by means of sealing air. This embodiment is particularly useful in connection with a heating of only a portion of the length of the channel or the waveguide body. In this way, the heating to the most relevant for the condensation area, as explained above, be limited, in addition due to the flow barrier from particular blocking air further flow of material vapors against the path of the laser light is prevented by the waveguide body. Advantageously, the fluid used for the flow barrier in this case has at least ambient temperature or is heated above ambient temperature.

In a particularly advantageous embodiment of the waveguide arrangement, this further has a cold trap, so that condensation takes place at a defined location. Due to the cold trap, the condensation can take place deliberately at a predeterminable point in or adjacent to the waveguide body. The selection of this point is made so that it is easily accessible from the outside, so that a simple cleaning is possible.

In a further preferred embodiment of the waveguide arrangement, this has, adjacent to the input end of the waveguide body, a plate for optical fibers of an optical fiber bundle which guide the light from the laser source in the direction of the waveguide body, the plate in particular comprising aluminum. In this way, a reliable coupling of the laser light in the waveguide body at the desired entrance angle, in particular in the channel of the waveguide body.

According to advantageous and alternative embodiments, different heating means are provided in the context of the waveguide arrangement. In general, it applies here that the heating means heats the waveguide body, wherein it is preferably not in direct contact with the channel, in particular in the case of the negative waveguide, ie in particular is not arranged in this or is passed through it. Thus, there is a separation between the heating means and the path of the laser light.

Furthermore, in each of the embodiments described below, a temperature sensor may be present which, in combination with a control unit, adjusts the detected actual temperature to a predefinable setpoint temperature, i. in particular regulates. Especially in combination with the temperature sensor, it is possible to set the temperature in the channel of the waveguide body to a temperature T, which is for example 10 K, preferably 5 K, above the dew point. In this way, the condensation can be effectively reduced or prevented while at the same time limiting the heating of the waveguide body to a required minimum. In this context, the temperature sensor does not have to detect the temperature in the channel itself, for example, but a detection of the temperature of the heating medium is sufficient. The temperature of the heating means is then correlated with the temperature in the channel, which depends on the material used for the waveguide body as well as the heating means used, which will become clear hereinafter.

In a first alternative, the heating means is an electrical heating means. This is, for example, an electric heater which is arranged around the waveguide body and heats it. Depending on the size of the waveguide body and the material used for this purpose, different preheating times arise until the desired temperature is achieved, in particular in the channel of the waveguide body, so that the condensation can be effectively prevented. In a particularly advantageous embodiment, the electrical heating means is therefore integrated in the waveguide body. This significantly reduces preheating time in particular and makes the arrangement more energy efficient overall.

According to a second alternative, the heating means is a liquid heating means. For this purpose, the waveguide body may be provided with a jacket which is flowed through by the liquid heating means and thus transfers the heat to the waveguide body, analogous to the externally arranged electrical heating means. It is preferred that the liquid heating medium flows through the waveguide body. For this purpose, corresponding channels are provided in the waveguide body, in particular meander-shaped channels, which extend over a first length of the waveguide body, so that the first region can be heated as desired. In particular, when using a liquid heating means, a second temperature sensor may be present. In this way, the temperature can be detected on entering the waveguide body and on exit from the waveguide body, which allows a conclusion as to whether the desired temperature has already been reached in the channel of the waveguide body.

A laser welding system according to the invention comprises a laser light source, a conductor for the laser light and a waveguide arrangement according to the invention, wherein laser light can be conducted from the laser light source by means of the conductor to the entrance end of the waveguide body. The conductor for the laser light preferably comprises at least one optical fiber bundle, with which the laser light can be conducted to the inlet end of the waveguide body during operation. Since the laser welding system according to the invention uses the waveguide arrangement according to the invention, reference is made to the above explanations in order to avoid unnecessary repetition in view of the resulting advantages.

According to the invention, a use of a material for at least a first component of the components to be welded with a laser welding system is provided whose dew point is below the temperature of a waveguide body adjacent to an exit end of the waveguide body during operation of the laser welding system. The material is in particular a plastic. Precisely because of the use of the appropriately selected material, the condensation of material vapors when welding the component to another component inside a negative waveguide body of a laser welding system can be reduced or preferably prevented. The other or second component is preferably also made of plastic, wherein a material selection is carried out in particular analogous to the first component. In a further preferred embodiment, therefore, a material is used for the second component whose dew point is below the temperature of the waveguide body adjacent to an exit end of the waveguide body during operation of the laser welding system.

In an equally advantageous embodiment, a laser welding system according to the invention is used for welding. With regard to the resulting advantages, reference is therefore made to the above statements. Thus, besides a selective selection of the material for at least one of the components, heating of the waveguide body also takes place in order to prevent condensation particularly effectively.

An inventive laser welding method in which two components are welded together by means of a laser welding system, in particular a first and a second plastic component, comprising the steps of arranging the components to be welded adjacent to an outlet end of a waveguide body of the laser welding system, driving a laser source and welding the two components together wherein, during welding, a dew point of the material of at least one of the two components to be welded is below a temperature of a first portion of the waveguide body adjacent to the exit end, and then turning off the laser light and removing the welded components from the laser welding system. The advantageous effect resulting from the consideration of the dew point has already been explained in detail above. Therefore, with regard to the corresponding advantages, we refer to the above statements.

In a preferred embodiment, the laser welding method comprises the further step of: selectively selecting the material of at least one component so that, during the welding, the dew point of the material lies below a temperature of a first region of the waveguide body adjacent to the outlet end.

In a further advantageous embodiment, a laser welding system according to the invention is present. The laser welding method therefore preferably comprises the further step of heating the first region of the waveguide body by means of a heating means to a temperature above the dew point for the material of at least one of the components to be welded. With regard to the resulting advantages, reference is made to the above explanations of the laser welding system according to the invention.

The laser welding method preferably has the further step in the presence of the laser welding system: detecting the actual temperature of the waveguide body in the first region by means of a temperature sensor and transmitting the detected actual temperature to a controller and comparing the detected and transmitted actual temperature with a predetermined target - Temperature for the waveguide body in the first region and adjusting the actual temperature of the waveguide body to the predetermined target temperature. According to an alternative, it is preferred that the detection of the actual temperature takes place indirectly by means of detecting the actual temperature of a heating fluid. In this context, it is further advantageous that the temperature is below a melting point of at least one of the components to be welded together. In this way, impressing or impressing, for example, the shape of the waveguide body is prevented in the component, so that an unwanted change in the appearance of the component is also prevented.

These steps are preferably carried out before welding the two components together, so that the waveguide body is preheated accordingly. The selected target temperature depends on the materials of the components to be welded together, in particular plastic components.

list of figures

• 1 eine schematische Schnittansicht eines Wellenleiters,
• 2 eine schematische Schnittansicht eines Wellenleiters mit Kanälen für Spülluft,
• 3 eine schematische Schnittansicht einer Ausführungsform einer erfindungsgemäßen Wellenleiteranordnung und
• 4 ein Flussdiagramm einer Ausführungsform eines erfindungsgemäßen Laserschweißverfahrens.

Hereinafter, the present invention will be described in detail with reference to the drawings. The same reference numerals in the drawings designate the same components and / or elements. Show it:

• 1 a schematic sectional view of a waveguide,
• 2 a schematic sectional view of a waveguide with channels for scavenging air,
• 3 a schematic sectional view of an embodiment of a waveguide assembly according to the invention and
• 4 a flowchart of an embodiment of a laser welding process according to the invention.

Detailed Description of the Preferred Embodiments

Hereinafter and in particular with reference to 1 First, the fundamental problem is shown that the present invention is based. 1 shows a waveguide body 10 a laser welding system. The laser welding system includes adjacent to the waveguide body 10 a laser light source, not shown, and a conductor 20 for the laser light. This directs the laser light from the laser light source to an entrance end 12 of the waveguide body 10 , The laser light then passes through a channel-shaped cavity in the waveguide body 10 , occurs at an exit end 14 out of this and hits the components to be welded 30 , The waveguide body 10 itself thus represents along the path of the laser light the last element of the laser welding system, before the laser light on the components to be welded together 30 meets.

In the operation of the laser welding system guest due to the heating of the plastic components 30 the material of at least one of the components 30 out. The resulting material vapors 40 are a hindrance to the proper functioning of the laser welding system, since the vapors inside the waveguide body 10 , ie on the walls of the channel-shaped cavity, knock down. A condensation of the vapors inside the waveguide body 10 causes the transmission of the laser radiation in the waveguide body 10 is negatively influenced.

Now referring to 2 A solution for preventing condensation is shown, as it is known from the basic operation. In contrast to the representation according to 1 is still a plate 116 provided the connection of the conductor 120 to the waveguide body 110 serves. Furthermore, a flushing channel 150 intended for purge air. A flow path of the purging air is by means of the arrows 154 shown.

Accordingly, the purge air flows from the entrance end 152 of the flushing channel 150 into the waveguide body 110 and between the waveguide body 110 and a bottom of the plate 116 in the direction of the channel for the laser light. Thereafter, the purging air flows through the laser light passage along the path of the laser light and exits at the exit end 156 from the waveguide body. The exit end 156 of the flushing channel 150 and the exit end 114 of the waveguide body 110 therefore agree. Due to this air purge inside the waveguide body 110 the material vapors are prevented from entering the channel.

Now referring to 3 an embodiment of a waveguide arrangement according to the invention is shown. The waveguide body 210 has in a known manner an entrance end 212 as well as an exit end 214 on. Adjacent to the entrance end 212 is a plate 216 provided for connecting the conductor 220 serves for laser light. The waveguide body itself is preferably made of steel and the channel inside the waveguide body 210 is coated with gold. However, other combinations of materials are preferred as long as the coating permits good reflection of the laser beams and the material of the waveguide body 210 has a good thermal conductivity.

Furthermore, in the example shown, heating means 260 into the waveguide body 210 integrated. By means of these heating means 260 will the Fiber body 210 heated before welding the two components together. The heating takes place at a temperature which is reliably above the dew point of the material of at least one of the two components to be welded together. In this way, condensation of the vapors or outgassing of the material during welding is reduced or preferably prevented by at least one of the two components.

The heating means 260 are adjacent to the exit end 214 arranged. Therefore, heating takes place from the exit end 214 , This is due to the fact that the waveguide body 210 at the exit end 214 usually in direct contact with one of the components, ie the material vapors from the outlet end 214 forth in the channel of the waveguide body 210 stream.

Furthermore, and with respect to the illustrated embodiment, the heating means 260 arranged so that the heated area is about 1/3 of the length of the waveguide body 210 starting from the exit end 214 extends. The length of the waveguide body 210 determined by the distance between the entrance end 212 and the exit end 214 along the path that the laser light passes through the waveguide body 210 takes.

A selection of the heated length depends in particular on the particular application and thus also on the components to be welded together or their materials. However, it was found that condensation occurs mainly in the lower half of the waveguide body 210 and especially in the lower third. The upper half and the upper part of the waveguide body 210 is usually not that bad.

However, in addition to the above-described embodiment, it is alternatively preferable to use the waveguide body 210 to heat over its entire length or over a length greater than 1/3, for example 50%.

The in the waveguide body 210 The existing channel can additionally be used to carry out scavenging air, as described in the embodiment according to FIG 2 was explained. Therefore, the waveguide body 210 also a flushing channel 250 with an entry end 252 and an exit end 254 for scavenging air on. This additionally helps to prevent condensation.

Alternatively to flowing through the channel in the waveguide body 210 with scavenging air, it is also preferred adjacent to the heated first area at the entrance end 212 of the waveguide body 210 facing end of the first region to provide a flow barrier, in particular by means of sealing air. In this way, the heating can be limited to the most relevant for the condensation area, in addition, due to the flow barrier of sealing air, a further flow of material vapors against the path of the laser light through the waveguide body 210 effectively preventable. In this case, it is preferred that the fluid used for the flow barrier has at least ambient temperature and is preferably heated to a temperature above it.

In the context of the waveguide arrangement are different heating means 260 intended. In addition to the illustrated integrated form of the heating means, it is also preferred if the heating means outside the waveguide body 210 is arranged and heated from there. Preferably, however, the heating means is not in direct contact with the channel in the waveguide body 210 , is thus in particular not arranged in this or is passed through this. Thus, there is a separation between the heating means and the path of the laser light.

Furthermore, a temperature sensor may be present, which adjusts the temperature in combination with a control unit, ie in particular regulates. Especially in combination with a temperature sensor is the possibility of the temperature in the channel of the waveguide body 210 to set a temperature T, which is for example 10 K, preferably 5 K, above the dew point. In this way, the condensation can be effectively reduced or prevented while at the same time heating the waveguide body 210 is limited to a required minimum.

In this context, the temperature sensor does not have to detect the temperature, for example, in the channel itself, but a detection of the temperature of the heating medium 260 is sufficient. The temperature of the heating medium 260 is then correlated to the temperature in the channel of the waveguide body 210 what depends on the material used for the waveguide body 210 used, as well as the heating medium used.

In a first alternative, the heating medium 260 an electric heating medium. This is, for example, an electric heater. According to a second alternative, the heating means is a liquid heating means. For this purpose, the waveguide body 210 be provided with a jacket in which the heating means is arranged. In the case of the liquid heating means, this jacket can be flowed through accordingly by the liquid heating means and thus transfer the heat to the waveguide body, analogously to an externally arranged electrical heating means.

It is preferred that the liquid heating means through the waveguide body 210 flows. These are in the waveguide body 210 corresponding channels, not shown, provided, in particular meandering channels extending over a first length of the waveguide body 210 extend so that the first area is heated as desired.

Especially when using a liquid heating means, a second temperature sensor may be present. In this way, the temperature of the liquid heating means when entering the waveguide body 210 and at the exit from the waveguide body 210 be detected, which allows a conclusion as to whether the desired temperature in the channel of the waveguide body 210 already achieved.

Referring now to 4 an embodiment of a laser welding method according to the invention is explained in which two components are welded together by means of a laser welding system, in particular a first and a second plastic component.

In a first step D, the material of at least one component is selected in such a way that, during the welding, the dew point of the material is below a temperature of a first region of the waveguide body 210 adjacent to the exit end 214 lies. In particular, due to the use of the appropriately selected material, the condensation of material vapors when welding the component to another component in the interior of the waveguide body 210 reduced or preferably prevented. The other or second component is advantageously also made of plastic, wherein a material selection is analogous to the first component.

The laser welding method preferably employs the above-described embodiment of the laser welding system in which the waveguide assembly has heating means 260 having. After, simultaneously with or before step D therefore takes place in step e heating the first region of the waveguide body 210 by means of the heating medium 260 to a temperature above the dew point for the material of at least one of the components to be welded. The step e includes the further steps F and G ,

In step F becomes the actual temperature of the waveguide body 210 detected in the first area by means of a temperature sensor and transmitted to a controller. Comparing the detected and transmitted actual temperature with a predetermined desired temperature for the waveguide body 210 in the first region and adjusting the actual temperature of the waveguide body 210 to the predetermined target temperature then takes place in step G. The detection of the actual temperature can be done directly or indirectly by detecting the actual temperature of the heating means itself, for example, the heating fluid.

In this context, it is further advantageous that the actual temperature is below a melting point of at least one of the components to be welded together. In this way, unwanted imprints, for example, by the waveguide body 210 avoided in the component. The selected target temperature thus depends on the materials of the components to be welded together, in particular plastic components.

In step A Now arranging the components to be welded adjacent to an outlet end 214 of the waveguide body 210 , Thereafter, the laser source is driven and the two components are interconnected in step B welded, wherein during the welding, a dew point of the material of at least one of the components is below a temperature of a first region of the waveguide body adjacent to the outlet end. Finally, in step C a shutdown of the laser light and a removal of the welded components from the laser welding system.

LIST OF REFERENCE NUMBERS

10

Fiber body

12

entry end

14

exit end

20

Head for laser light

30

components

40

material vapors

110

Fiber body

112

entry end

114

exit end

116

plate

120

Head for laser light

130

components

150

irrigation channel

152

entry end

154

flow

156

exit end

210

Fiber body

212

entry end

214

exit end

216

plate

220

Head for laser light

250

irrigation channel

252

entry end

256

exit end

260

heating

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004058221 A1 [0004]
• DE 112007002109 T5 [0004]
• EP 1987944 A1 [0007]

Claims (22)

Waveguide assembly of a laser welding system comprising a. a waveguide body with a1. an entrance end through which laser light from a laser source enters the waveguide body during operation, and a2. an exit end, through which the laser light leaves the waveguide body during operation and which, in operation, is arranged adjacent to two components to be welded together, and b. a heating means, with which at least a first region of the waveguide body adjacent to the outlet end can be heated to a temperature which is above a dew point of the material of at least one of the two components to be welded together in operation. Waveguide arrangement according to Claim 1 in which a channel is formed in the waveguide body between the inlet end and the outlet end, through which the laser light passes during operation and on whose side surfaces the laser light is reflected. A waveguide arrangement according to any one of the preceding claims, in which the waveguide body is heated over its entire length or the first area is 50% of a length of the waveguide body, preferably 1/3 of the length. Waveguide arrangement according to one of the preceding claims, in which, adjacent to the first region at the inlet end of the waveguide body facing the end of the first region, a flow barrier is provided, in particular by means of sealing air. A waveguide assembly according to any one of the preceding claims, further comprising a cold trap such that condensation occurs at a defined location. Waveguide arrangement according to one of the preceding Claims 2 - 5 wherein the waveguide body is made of steel and the channel is coated with gold. A waveguide assembly as claimed in any one of the preceding claims, further comprising, adjacent the entrance end, a fiber optic fiber optic bundle plate directing the light from the laser source towards the waveguide body, the plate comprising, in particular, aluminum. A waveguide assembly according to any one of the preceding claims, wherein the heating means is an electrical heating means. Waveguide arrangement according to Claim 8 in which the electrical heating means is integrated in the waveguide body. Waveguide arrangement according to one of Claims 1 to 7 in which the heating medium is a liquid heating medium. Waveguide arrangement according to Claim 10 wherein the liquid heating medium flows through the waveguide body. Laser welding system comprising: a laser light source, a conductor for the laser light as well a waveguide arrangement according to one of the preceding claims, wherein laser light from the laser light source by means of the conductor to the inlet end of the waveguide body is conductive. Use of a material for at least a first component of the components to be welded with a laser welding system whose dew point is below the temperature of a waveguide body adjacent to an exit end of the waveguide body during operation of the laser welding system. Use according to Claim 13 , wherein for welding a laser welding system according to Claim 12 is used. Use according to Claim 13 or 14 wherein the material comprises a plastic. Use according to one of Claims 13 to 15 wherein, for a second component, a material is used whose dew point is below the temperature of the waveguide body adjacent to an exit end of the waveguide body during operation of the laser welding system. Laser welding method in which two components are welded together by means of a laser welding system, in particular a first and a second plastic component, comprising the steps: a. Arranging the components to be welded adjacent to an exit end of a waveguide body of the laser welding system, b. Driving a laser source and welding the two components together, wherein during welding a dew point of the material of at least one of the two components to be welded together is below a temperature of a first portion of the waveguide body adjacent the exit end, and thereafter c. Switching off the laser light and removing the welded together components from the laser welding system. Laser welding method according to Claim 17 comprising the further step: d. selectively selecting the material of at least one component such that, during welding, the dew point of the material is below a temperature of a first portion of the waveguide body adjacent the exit end. Laser welding method according to Claim 17 or 18 , which is a laser welding system according to Claim 12 and comprising the further step: e. Heating the first portion of the waveguide body by means of a heating means to a temperature above the dew point for the material of at least one of the components to be welded. Laser welding method according to Claim 19 , which further comprises: f. Detecting the actual temperature of the waveguide body in the first region by means of a temperature sensor and transmitting the detected actual temperature to a controller and g. Comparing the detected and transmitted actual temperature with a predetermined target temperature for the waveguide body in the first region and setting the actual temperature of the waveguide body to the predetermined target temperature. Laser welding method according to Claim 20 wherein the detection of the actual temperature is carried out indirectly by detecting the actual temperature of a heating fluid. Laser welding method according to one of Claims 19 to 21 , wherein the temperature is below a melting point of at least one of the components to be welded together.

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