WO2008125573A1

WO2008125573A1 - Gas and coolant nozzle

Info

Publication number: WO2008125573A1
Application number: PCT/EP2008/054305
Authority: WO
Inventors: Detlef Meyer; Werner Staudinger; Michael Mues
Original assignee: Thyssenkrupp Steel Ag
Priority date: 2007-04-12
Filing date: 2008-04-09
Publication date: 2008-10-23
Also published as: DE102007017616B3

Abstract

The invention relates to a device (1) for supplying gas and coolant to the process zone during welding, particularly laser welding, comprising at least one gas nozzle (2) having a gas conducting channel (3) and at least one coolant nozzle (4) arranged beneath the gas nozzle, the coolant nozzle having a coolant conducting channel (5), wherein the gas conducting channel (3) of the gas nozzle (2) is arranged such that the gas is fed to the process zone (S) in a piercing manner and the coolant nozzle (4) is arranged such that it is in thermal contact with the gas nozzle (2) and cooling of the gas nozzle (2) occurs. The aim of providing a generic device, which allows high process reliability when welding, or laser welding, critical materials at high speed, is achieved in that the coolant nozzle (4) has a coolant outlet bore (7) connected to the coolant conducting channel (5), wherein the coolant outlet bore (7) runs counter to the welding direction (A) in the coolant outlet direction and ends in an outer groove (8) of the coolant nozzle (4).

Description

Gas and coolant nozzle

The invention relates to a device for feeding gas and coolant into the process zone during welding, in particular during laser welding, with at least one gas nozzle with a gas guide channel and at least one coolant nozzle with a coolant guide channel, wherein the gas guide channel of the gas nozzle is arranged such that the gas stabbing the process zone is supplied and the Kuhlmittelduse is arranged so that it is in thermal contact with the Gasduse and cooling of the gas nozzle takes place. In addition, the invention relates to a method for laser welding of components, in particular sheets or strips.

When welding or laser welding sheet metal, which are used for example for the body shop, the weld quality is particularly important. This is determined on the one hand by the heat transfer and on the other hand by a good cooling of the weld in order to avoid thermal expansion effects of the sheets. For this purpose, known from the prior art gas and Kuhlmitteldusen, which supply the process zone to increase the heat input on the one hand an inert gas, preferably helium, and on the other hand cool the weld by a coolant, usually a gas-water mixture, sluggish to the welding direction , The gas supply is usually stinging, ie in the welding direction or opposite to the transport direction of the sheets to be welded. For example, German Patent Application DE 195 37 924 A1 discloses a nozzle for supplying process gas and coolant to the process zone during laser welding, the gas nozzle of which has a gas guide channel and its coolant nozzle a coolant guide channel, the gas being supplied to the process zone in a piercing manner and the weld behind the process zone is cooled by the supply of cooling agents. The achieved with the known device welding speeds, however, no longer meet today's cost-effectiveness requirements, especially if not technically difficult

Steel alloys, such as 22MnB5 steel alloys to be welded. In addition, the previously known devices were limited to the use of helium as an inert gas. Helium, however, is a very expensive inert gas whose use should be minimized wherever possible.

The same applies to those from the German

Offenlegungsschπft DE 197 08 047 Al known device for supplying gas and Kuhlmittel in the process zone during the laser welding, which has a slotted nozzle for applying a gas-water mixture to the weld to cool the weld.

Proceeding from this, the present invention has the object to provide a generic device for disposal, which allows high process reliability welding or laser welding of critical materials at high speed. About that In addition, the invention has for its object to propose an advantageous laser welding process.

According to a first teaching of the present invention, the above-described object is achieved for a generic device for supplying gas and Kuhlmittel in the process zone during welding, in particular during laser welding characterized in that the Kuhlmittelduse having a Kuhlmittelfuhrungskanal Kuhlmittelaustπttsbohrung, wherein the Kuhlmittelaustrittsbohrung runs in Kuhlmittelaustrittsrichtung opposite to the welding direction and ends in an outer groove of Kuhlmittelduse.

It has surprisingly been found that the coolant at the Kuhlmittelaustπttsoffnung forms a parallel to the weld extending Kuhlmittelvorhang due to the existing groove, which achieves excellent cooling of the weld with reduced use of coolant, with very good shrinkage stresses are achieved at the weld joint. Since the Kuhlmittelzufuhrung, preferably used as Kuhlmittel water, sluggish to the welding direction, the water is not introduced into the process zone. This significantly increases the process reliability of welding or laser welding. The reason for the good Kuhlverhalten while low flow rate of coolant is seen in the fact that even at low Kuhlmitteldurchflussmengen due to the groove on the Kuhlmittelduse a relatively large Kuhlmitt curtain forms. This changes its size depending on the coolant flow rate. According to a first embodiment of the present invention, the Kuhlemittelduse Kuhlverhalten is further improved in that the groove is disposed on the Kuhlmittelduse immediately opposite the weld and runs from the Kuhlmittelaustrittsoffnung opposite to the welding direction. On the one hand, the coolant curtain forming in this case automatically wets the weld seam, on the other hand, as a result the coolant curtain increases as the coolant flow rate increases in the opposite direction to the welding direction. The cooling can be easily adapted to the welding speed with little use of coolant.

A running along the Kuhlmittelvorhangs below the Kuhlmittelduse and thus its enlargement without tearing the Kuhlmittelvorhangs of Kuhlmittelduse is facilitated by the fact that the groove has a chamfer at the opposite end of Kuhlmittelaustrittsoffnung.

If the coolant guide channel of the coolant nozzle extends at least partially parallel to the gas guide channel of the gas nozzle, it can be cooled particularly effectively, as a result of which the density of the gases supplied to the process zone can be kept constant. This additionally improves the process reliability of the welding or laser welding.

The design of the Kuhlmittelvorhangs is further improved by the fact that the angle between the Kuhlmittelfuhrungskanal and Kuhlmittelaustrittsbohrung 20 ° to 50 °, preferably 30 ° to 40 ° amounts.

In addition, the inventive device allows the use of mixed gases as process gases in that the angle between the gas and / or Kuhlmittelduse to be welded sheet or component amounts to 10 ° to 40 °, preferably 20 ° to 30 °. The angle that is more acute than the use of helium is due to the increased density of the mixed gases, for example consisting of argon, helium and carbon dioxide or oxygen.

Preferably, the gas nozzle and / or the Kuhlmittelduse are constructed of a Dusenkorper and a losbarbar attached to this Dusenendstuck, which are preferably pinned together. The Dusenendkorper in its geometry and its distance from the process zone of welding has a significant Emfluss on the plasma shielding in the welding process and thus on the Emkopplung, for example, the laser power in the material. In this respect, the losbaren Dusenendkorper on the material, the laser power and the process used. Inert gas tuned Dusenendkorper be used. For example, an altered process gas mixture can thus also be taken into account. The optional pinning of the Dusenendkorpers with the Dusenkorper a particularly accurate positioning of Dusenendkorpers is achieved even after a change of Dusenendkorpers.

If the Kuhlmittelduse at least in the area of Dusenendstucks directly to the Gasduse on, can particularly effective cooling of the gas nozzle can be achieved by the coolant. As already stated, this further stabilizes the welding process.

To improve the heat conduction between the gas nozzle and the coolant nozzle, the gas nozzle and / or the coolant nozzle consist of a highly thermally conductive metal, in particular copper or a copper alloy. Copper has the advantage that it is also easily machinable.

An optimal cooling of the gas nozzle by the coolant nozzle is achieved in that the gas nozzle are integral with the coolant nozzle or its nozzle body and / or nozzle end pieces.

Preferably, the cross-sectional area of the gas guide channel, in particular in the region of the gas outlet, is at least 10 mm ² , preferably at least 25 mm ² . With a cross-sectional area of at least 10 mm ² , pure helium can also be used as the process gas. Optimal for the use of mixed gases as process gases is a cross-sectional area of at least 25 mm ² . Relative to a circular cross-section of

Gas outlet means that the diameter is at least 3.5 mm or at least 6 mm. The gas outlet opening of the gas nozzle may have any cross-sectional shapes. Preference is given to circular, oval or polygonal cross-sectional shapes.

Since the gas and coolant nozzle must be precisely aligned in order to achieve optimum process control, it is advantageous if for Alignment of the gas and / or coolant nozzle Justagemittel are provided.

A particularly easy replacement of the gas and / or coolant nozzle can be ensured that an adapter plate is provided as a nozzle holder, which preferably has receptacles for the Justagemittel. The adapter plate is also suitable to provide, for example, the supply of gas and coolant with quick couplings, so that a very fast, reliable exchange of the nozzle body can be done with the nozzle end. About the Justagemittel, which are received in the adapter plate, the nozzle body including nozzle end piece can be easily adjusted.

According to a second teaching of the present invention, the object indicated above is achieved by a method for laser welding of components, in particular metal sheets, using the device according to the invention. As already stated, when using the device according to the invention in laser welding, the laser welding speed can be increased despite reduced coolant consumption.

The cost of the inventive method for welding components or sheets can be reduced by using a mixed gas comprising helium, argon and carbon dioxide or oxygen. This mixed gas is significantly cheaper to manufacture, since a smaller proportion of helium is included. An increase in cost-effectiveness can be achieved according to a next embodiment of the method according to the invention in that the

Laser welding speed is at least 8 to 10 m / min. In particular when using mixed gases, such a high laser welding speed has not yet been reliably achieved.

Advantages result from the fact that, according to a further embodiment of the method according to the invention sheets of a soft, high or very high strength steel alloy, in particular a steel alloy type 22MnB5 are welded, wherein the sheets preferably have a coating, in particular an Al-Si coating. Soft steel alloys are in principle easier to weld than high-strength or ultra-high-strength steel alloys. However, advantages arise with these steel alloys by the method according to the invention due to the increased process reliability, which allows higher welding speeds and the reduced costs. The high and ultra-high strength steel alloys as well as the steel alloy type 22MnB5 do not have such good welding properties. But they are preferred due to their excellent strength and deformation properties in the body, mostly coated, used. However, coatings such as aluminum-silicon (Al-Si) coating negatively affect the welding process. The same applies, but to a lesser extent, for elo- or hot-dip galvanized sheets. The high process reliability in laser welding using the device according to the invention enables the welding of the latter, coated High-speed metal sheets using mixed gases as the process gas.

There are now a variety of ways to further develop and design the device according to the invention or the inventive method. For this purpose, on the one hand reference is made to the patent claims 1 and 14 subordinate claims, on the other hand to the description of an embodiment of a device in conjunction with the drawing. The drawing shows in

1 shows an embodiment of an apparatus according to the invention for supplying gas and coolant into the process zone during welding in a lateral cross-sectional view,

Fig. 2 in an enlarged view the

Cross-sectional view of the tip of the nozzle end of the embodiment of FIG. 1 and FIG

3 is a plan view of the nozzle end of the

Embodiment of FIG. 1.

FIG. 1 shows an exemplary embodiment of the device 1 according to the invention for feeding gas and coolant into the process zone during welding in a lateral cross-sectional view with a sectional plane in the welding direction. The apparatus 1 for supplying gas and coolant into the process zone during welding consists of a gas nozzle 2 with a gas guide channel 3 and a below The gas nozzle 2 is arranged with respect to the welding direction A so that the gas flowing through the gas guide channel 3 process gas of the welding zone S stabbing, ie opposite to the transport direction T of the sheets 6 is supplied. In the present embodiment, the beam path of a laser welding beam is shown with L, which causes the welding of the sheets 6 in the process zone S. The coolant nozzle 4 is arranged so that the gas nozzle 2 is cooled by the coolant flowing through the coolant guide channel 5, for example water, the gas nozzle 2. This results in that the density of the gas medium, which flows through the gas guide channel 3, can be kept constant during the laser welding. The process gas is particularly important to control the plasma shield and thus the heat input during laser welding. Due to the constant density of the gases, process reliability is therefore increased. The coolant guide channel 5 of the coolant nozzle has a coolant outlet bore 7, which will be described in detail later in detail. This coolant outlet bore extends opposite to the welding direction A or in the transport direction T of the plates 6. The coolant nozzle 4 is intended to effect a particularly effective cooling of the weld seam of the plates 6. To this ends according to the invention, as shown in the present embodiment, the

Coolant outlet bore in an outer groove 8 of the coolant nozzle 4. This configuration of the coolant outlet bore 7, depending on the medium flowing through a coolant curtain 9 is generated, which is in the transport direction T on the weld the sheets 6 extends. The size of the coolant curtain 9 is influenced by the flow rate of the coolant. For example, the coolant curtain 9 can be extended by increasing the flow rate in the transport direction T. This is necessary, for example, if the

Welding speeds are increased. The groove 8 of the coolant nozzle 4 is preferably, as in the illustrated embodiment, arranged directly opposite the weld, so that the coolant curtain 9 can be positioned exactly above the weld.

The angle α between the coolant guide channel 5 and the coolant outlet bore 7 is between 20 ° and 50 °, preferably between 30 ° and 40 °. For better heat transfer, the gas nozzle 2 and the coolant nozzle 4 are made in one piece from a single piece of metal, to increase the flexibility with respect to the use of different process gases or laser welding conditions, the device 1 has a nozzle end 10, a nozzle body 11 and an adapter plate 12. The nozzle end 10 is connected via screws 13 and 14 to the nozzle body 11. In addition, the nozzle end piece is pinned to improve the positioning accuracy thereof with the nozzle body 11 via pins not shown in FIG.

As already stated, the supply of the process gas and the subsequent cooling is decisive for the quality of the welded seam of the welded sheets. To allow an adjustment of the device 1 according to the invention in a simple manner, are in the embodiment shown in FIG. 1 adjustment means 15, 16 and the associated receptacles 17 and 18 are provided in the nozzle body 11 and in the adapter plate 12. In Fig. 1, only two screws 15,16 are shown as adjusting means, but usually at least three screws are provided to allow adjustment in all three spatial directions. In the illustrated embodiment also quick-release couplings 19 and 20 are provided to allow a particularly rapid replacement of the device according to the invention. All transitions between the adapter plate 12, nozzle body 11 and nozzle end 10 are sealed via not shown O-rings, so that no gas or coolant losses occur.

The embodiment of a device for supplying gas and coolant into the process zone during welding, illustrated in FIG. 1, is designed for the use of mixed gases instead of pure helium. For this purpose, the angle β between the sheets 6 to be welded and the gas nozzle 2 is 10 ° to 40 °, preferably 20 ° to 30 °. Due to this shallow inlet angle β of the process gas, the density of the mixed gas, which is significantly larger compared to helium, is taken into account. Compared to the optimized for the use of helium gas nozzles, the embodiment of the invention also has a larger cross-sectional area of the gas guide channel 3. This is in the illustrated embodiment about 28 mm ² , which corresponds to a diameter of the gas guide channel 3 of 6 mm.

With the exemplary embodiment illustrated in FIG. 1, welding speeds of more than 8 to 10 m / min have been achieved in practice, even if critical welding steel alloys, such as 22MnB5 steel alloys were welded. This was achieved in particular using mixed gases, which consist of a gas mixture of helium, argon and carbon dioxide or oxygen.

The cross-sectional view of the tip of the nozzle end 10 is additionally shown in detail in FIG. The gas guide channel 3 and the coolant guide channel 5 extend parallel to one another in the area of the tip of the nozzle end piece, with the coolant nozzle 4 resting directly on the gas nozzle 2. In the present case this is achieved in that the gas nozzle 2 and the coolant nozzle 4 are integral. Of the

Coolant guide channel 5 is in welding direction A, i. closed in the gas outlet direction and formed as a blind hole. The beginning of the bottom of the blind hole and aligned in the direction of transport A.

Coolant outlet bore 7 terminates at the other end in an outer groove 8 of the coolant nozzle 4. By this arrangement it is achieved that the speed of the exiting coolant is reduced and between the end of the coolant outlet bore 7 and the coolant nozzle 4 itself a downwardly hanging coolant curtain 9, which is not shown in Fig. 2, results in flow of the coolant through the coolant guide channel 5. The arrows in Fig. 2 indicate in the coolant guide channel, the direction of movement of the coolant, preferably water. Likewise, in the gas guide channel 3, the direction of the gas outlet is shown by an arrow. In order to improve the design of the coolant curtain, the groove 8 of the coolant nozzle 4, opposite the coolant outlet bore 7, has a chamfer 21. This transition to the outer surface of the coolant nozzle 4 allows the coolant curtain to run along the coolant nozzle 4, for example, as the flow rate of coolant increases, rather than tearing it off. As a result, a stronger wetting of the weld with coolant is achieved and the cooling effect is enhanced.

Fig. 3 now shows a plan view of the nozzle end 10 of the embodiment of Fig. 1 of the device according to the invention for supplying gas and coolant in the process zone during welding. First, the screws 13, 14, with which the nozzle end 10 is screwed to the nozzle body 11 can be seen.

In addition, the pins 22, 23 are shown, with which the nozzle body 11 is pinned to the nozzle end piece 10. As a result, a very exact positioning of the nozzle end piece is achieved relative to the nozzle body 11. Finally, FIG. 3 shows that the nozzle end piece has been produced from a single piece of metal, so that the heat transfer between the coolant nozzle 4 and the gas nozzle 2 is optimized and effective cooling of the process gas by the coolant nozzle 4 can take place. Preferably, both the nozzle body 11 and the nozzle end 10 is constructed of a material with very good heat conduction, for example copper or a copper alloy. However, it is also quite possible to use other materials for producing the nozzle body 11, the adapter plate 12 and the nozzle end piece 10.

Claims

PATENT AT SPRU

Anspruch [en] A device (1) for feeding gas and coolant into the process zone during welding, in particular during laser welding, with at least one gas nozzle (2) having a gas guide channel (3) and at least one coolant nozzle (4) arranged below the gas nozzle Kühlmittelfuhrungskanal

(5), wherein the Gasfuhrungskanal (3) of the gas nozzle (2) is arranged so that the gas piercing the process zone

(S) is supplied and the Kuhlmittelduse (4) is arranged so that it is in thermal contact with the Gasduse (2) and a cooling of the Gasduse (2), characterized in that the Kuhlmittelduse (4) with the Kuhlmittelfuhrungskanal (5 ) Kuhlmittelaustπttsbohrung (7), wherein the Kuhlmittelaustrittsbohrung in

Kuhlmittelaustrittsnchtung opposite to the welding direction (A) runs and in an outer groove

(8) the coolant nozzle (4) ends.

2. Device according to claim 1, characterized in that the groove (8) on the Kuhlmittelduse (4) is arranged directly opposite the weld and from the Kuhlmittelaustπttsoffnung (7) from opposite to the welding direction (A) runs.

3. A device according to claim 1 or 2, d a d u r c h e c e n e c e s e s, e e s the groove (8) at the opposite end of the coolant outlet opening has a chamfer (21).

4. Device according to one of claims 1 to 3, d a d u r c h e k e n e c e s e, s t a s s the coolant supply channel (5) of the coolant nozzle (4) at least partially parallel to the gas guide channel (3) of the gas nozzle (2).

5. Device according to one of claims 1 to 4, d a d u r c h e c e n e c e s e s, the angle (α) between the coolant guide channel

(4) and the coolant outlet bore (7) is 20 ° to 50 °, preferably 30 ° to 40 °.

6. Device according to one of claims 1 to 5, characterized in that the angle (ß) between the gas and / or coolant nozzle (2, 4) to the welded components or sheets (6) 10 ° to 40 °, preferably 20 ° to 30 °.

7. Device according to one of claims 1 to 6, characterized in that the gas nozzle and / or the coolant nozzle (2, 4) of a nozzle body (11) and a releasably secured thereto nozzle end piece (10) are constructed, which are preferably pinned together.

8. Device according to one of claims 1 to 7, d a d u r c h e c e n e c e s in that the coolant nozzle (4) rests directly against the gas nozzle (2) at least in the area of the nozzle end piece (10).

9. Device according to claim 1, wherein the gas nozzle and / or the coolant nozzle (2, 4) consist at least partially of a highly thermally conductive metal, preferably copper or a copper alloy.

10. The apparatus as claimed in claim 1, wherein the gas nozzle is integrated in one piece with the coolant nozzle or its nozzle body and / or nozzle end pieces.

11. Device according to one of claims 1 to 10, characterized in that the cross-sectional area of the gas guide channel (5), in particular in the region of the gas outlet at least 10 mm ² , preferably at least 25 mm ² .

12. Device according to one of claims 1 to 11, d a d u c h e c e n e c e s e s, e s s s for alignment of the gas and / or coolant nozzle (2, 4) adjustment means (15, 16) are provided.

13. Device according to one of claims 1 to 12, characterized in that provided as a nozzle holder, an adapter plate (12) is, which preferably has receptacles for the adjustment means (15, 16).

14. A method for laser welding of sheets and strips using a device according to one of claims 1 to 13.

15. The process of claim 14, wherein a mixed gas comprising helium, argon and carbon dioxide or oxygen is used as the process gas.

16. The method of claim 14 or 15, wherein said laser welding speed is at least 8 to 15 seconds

10 m / min.

17. Method according to claim 14, wherein the sheets are welded from a soft, high or very high strength steel alloy, in particular a steel alloy of the 22MnB5 type, wherein the sheets preferably have a coating, in particular an AlSi coating.