WO2017078524A1

WO2017078524A1 - Method for laser cladding

Info

Publication number: WO2017078524A1
Application number: PCT/NL2016/050765
Authority: WO
Inventors: Joseph Wilhelmus Maria MENS; Wim HUSSLAGE
Original assignee: Laser Clad Company B.V.
Priority date: 2015-11-06
Filing date: 2016-11-04
Publication date: 2017-05-11
Also published as: NL2015734B1

Abstract

The invention relates to a method for laser cladding an interior surface of a hollow open ended pipe, the method comprising; -manipulating of a laser beam over the interior surface of the pipe to form a line shaped melting, -supplying powder to the melting pool simultaneously and evenly along the entire length of the melting pool in order to uniformly grow a material layer on the interior surface of the hollow pipe.

Description

Method for laser cladding

Background The present invention relates to a method for laser cladding an interior surface of a hollow open ended pipe.

It is known to direct a laser beam to the interior surface of the pipe to provide a dot shaped melting pool, and then to supply powder to the melting pool to grow a material layer on the interior surface of the hollow pipe. The dot shaped melting pool slowly moves along the interior surface to grow the material layer.

Regarding coating in general, from BE1000078A6 it is known to internally coat a tube by plasma powder spraying to form a deposit which inhibits crack formation or propagation in the tube resulting from stress corrosion. The range in length of pipe that can be plasma sprayed seems limited.

The invention further relates to a device for laser cladding an interior surface of a hollow open ended pipe.

Laser cladding is a type of material adding technology. In general laser cladding is a method of depositing material. A powdered or wire feedstock material is melted and consolidated by use of a laser. Laser cladding is used to coat parts of a substrate or even fabricate a near-net shape part referred to as additive manufacturing technology. In case of coating parts, the cladded coating improves mechanical properties of the coated part, increases corrosion resistance, increases wear resistance and/or repairs worn out parts.

Summary of the invention

The invention aims to provide a method for cladding an interior surface of a hollow pipe which method is more affordable and provides a better quality of the coating layer. Another object of the invention is to improve a known method for cladding an interior surface of a hollow pipe in that a drawback associated with that method is at least partly solved.

Yet another object of the invention is to provide an alternative method for cladding an interior surface of a hollow pipe. According to a first aspect of the invention this is realized with a method for laser cladding an interior surface of a hollow open ended pipe, the method comprising;

manipulating of a laser beam over the interior surface of the pipe to form a line shaped melting pool,

- supplying powder to the melting pool simultaneously and evenly along the entire length of the melting pool in order to uniformly grow a material layer on the interior surface of the hollow pipe.

Manipulating of the laser beam over the interior surface of the pipe to form a line shaped melting pool enables to grow a more uniform material layer on the interior surface of the pipe. In addition, the process is potentially faster since the material layer can grow along the entire length of the melting pool. The material layer is also referred to as a laserclad layer.

Thus, according to the invention, power of the laser is distributed to cause a line shaped melting pool having a melting pool length, while powder is supplied to the melting pool simultaneously and evenly along the entire length of the melting pool. In contrast, in the art the laserclad layer only grows spot wise.

Optionally, the pipe is maintained in a stationary position while manipulating the laser beam over the interior surface of the pipe to form a line shaped melting pool. This is beneficial since theses pipes can have a considerable weight and have a length of more than several meters.

The method of the invention has its use in demanding industries like the oil, gas and chemical industry.

In connection with the invention a high power laser beam is as an example able to supply 10 kW for treatment of a pipe with a diameter of 100 mm.

It will be clear the invention is not limited to pipes that are entirely hollow. It is conceivable that the pipe has a closed or solid section. The invention is in particular beneficial for cladding a cavity of a hollow that has a minimal length of e.g. at least about 2 meters.

In an embodiment of the method, the manipulating of a laser beam comprises;

- introducing the laser beam into the interior of the pipe so that a center line of the laser coincides with a longitudinal axis of the pipe, and

deflecting the laser beam towards the interior surface of the pipe. This enables to cover the entire interior surface of the pipe while using one source of laser light.

In an embodiment of the method, the deflecting the laser beam towards the interior surface of the pipe comprises deflecting the laser beam at an included angle δ of less than 90°, in particular at an included angle δ of about 35°.

The manipulating a laser beam to form a melting pool comprises manipulating the laser beam to form a melting pool that extends around the inner circumference of the pipe to form a continuous annular shaped melting pool.

This even more enables to grow a more uniform material layer on the interior surface of the pipe.

In an embodiment of the method, the manipulating a laser beam to form a melting pool comprises manipulating the laser beam to form a melting pool that extends around the inner circumference of the pipe to form an discontinuous annular shaped melting pool, wherein discontinuities of the melting pool are caused by switching the laser beam on and off.

This enables to create discontinuities in the laserclad layer. This can be advantageous when e.g. a connection to the pipe must be made at a specific pipe section. In an embodiment of the method, the manipulating a laser beam to form a melting pool comprises manipulating the laser beam to form a melting pool that extends transverse with respect to the longitudinal axis of the pipe.

The melting pool extending transverse with respect to the longitudinal axis of the pipe facilitates to distribute the energy of the laser in a uniform way along the interior surface of the pipe.

In an embodiment of the method, the melting pool is continuous and has a circular shape. For that purpose, the laser beam continuously scans the interior surface of the pipe along a circular path.

This continuous and circular melting pool even more enables to grow a more uniform material layer on the interior surface of the pipe and aids in driving impurities away from the material layer already deposited on the interior surface of the pipe. In an embodiment, the method comprises manipulating the laser beam to move the melting pool along the longitudinal axis of the pipe.

Moving the melting pool along the longitudinal axis of the pipe enables growth of the material layer.

According to a further aspect of the invention this is realized with a device for laser cladding an interior surface of an hollow open ended pipe, the device comprising; a vehicle for travelling along a longitudinal axis of the hollow pipe and supporting an optical system and a powder distributing system,

- the optical system being configured for receiving and deflecting a high power laser beam,

wherein the optical system comprises means for manipulating the laser beam over an interior surface of the pipe to form a melting pool that extends around the inner circumference of the pipe to form an continuous annular shaped melting pool, and - the powder distributing system being configured for supplying powder to the melting pool simultaneously and evenly along the entire length of the melting pool in order to uniformly grow a material layer (6) on the interior surface of the hollow pipe to form a material layer on the interior surface of the hollow pipe.

The vehicle for travelling along a longitudinal axis of the hollow pipe allows to clad the entire interior surface of the pipe. The vehicle may roll or slide or move in any suitable manner through the pipe. It will be clear that the device is able to perform the method according to the invention and brings the same benefits associated therewith. In an embodiment of the device, the means for manipulating the laser beam comprises a movably arranged mirror, in particular a rotatably arranged mirror. The mirror reflects the laser towards the interior surface of the pipe. By moving the mirror, the laser beam is manipulated over the interior surface of the pipe to form a line shaped melting pool. The power of the laser is distributed over the melting pool. The power of the laser is distributed over the melting pool by continuously moving the laser beam, in particular repeatedly moving of laser beam along the melting pool. The rotatably arranged mirror is beneficial for continuously and repeatedly moving the laser beam along a circular melting pool. Therefore, the rotatably arranged mirror has an angular velocity which velocity is sufficient to distribute the power of the laser over the melting pool. As an example, the rotatably arranged mirror has an angular velocity of between 100 and 1000 rad/s or even more.

In an embodiment of the device, the powder distributing system comprises a nozzle arranged with respect to the means for manipulating the laser beam such that the laser beam is deflected past the nozzle and turns to the melting pool.

This arrangement of the nozzle and mirror facilitates the supply of powder to the melting pool. In an embodiment of the device, the powder distributing system comprises a rotatably arranged member, and wherein the nozzle is mounted with the rotatably arranged member for supplying powder simultaneously and evenly along the length of the melting pool in order to uniformly grow the material layer.

The rotatably arranged member provided with the nozzle enables to create a uniform flow of powder towards the interior surface of the pipe. The flow of powder can also be referred to as "powder front". The "uniformity" is related to the powder front over the circumference, as well as the powder front over time.

In an embodiment of the device, the rotatably arranged member comprises a supply channel for powder supply to the nozzle, wherein at least a section of the supply channel extends at an angle φ with respect to a radius r of the rotatably arranged member in order to effect the supply of powder in particular the powder velocity. In an embodiment of the device, the supply channel has a supply channel length 1, the nozzle has an outflow opening having an outflow diameter d, and wherein the supply channel length, the radius r of the rotatably arranged member, the angle φ and the outflow diameter are configured such that at a predetermined angular velocity of the rotatably arranged member, a uniform flow of powder flows towards the melting pool..

In an embodiment of the device, the powder distributing system comprises a plurality of nozzles mutually arranged for evenly supplying of powder along a length of the melting pool. Each nozzle may have its own respective supply channel. In an embodiment, the device comprises a gas powered drive system coupled with the powder distributing system and the means for manipulating the laser beam for rotating the rotatably arranged mirror and/or the rotatably arranged member.

This way, a flow of pressurized gas can both generate the flow of powder and drive the mirror.

In an embodiment of the device, the rotatably arranged mirror and the rotatably arranged member are coupled such that they rotate in unity.

The invention further relates to pipe laser cladded with the method according to the invention.

The invention further relates device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The invention further relates to a method comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages.

Description of the drawings The invention will be further elucidated referring to a preferred embodiment shown in the schematic drawings wherein shown in:

Fig. 1 in cross sectional side view a device according the invention in a hollow pipe; and

fig. 2 a detail of the device according to fig. 1 in a partially sectional- and cut-away view.

Detailed description of embodiments

In the figure 1 a device 9 according the invention is depicted in the interior 7 of a hollow pipe 2.

The device 9 is suitable and intended for laser cladding an interior surface 1 of a hollow open ended pipe 2. The device 9 comprising vehicle 10 for travelling along a longitudinal axis 8 of the hollow pipe 2. The vehicle 10 advances through the pipe in any suitable manner. The vehicle 10 moves to the right as seen in the fig. 1.

The vehicle 10 supports an optical system 11. The optical system 11 is configured for receiving and deflecting a high power laser beam 3. The optical system comprises a mirror 13 for manipulating the laser beam 3 over an interior surface 1 of the pipe 2. The laser beam 3 is manipulated according a pattern such that a line shaped melting pool 4 is formed. The melting pool 4 is depicted with a dashed line. The mirror 13 is arranged with the optical system 11 in a movable manner, in this case in a rotatable manner. The mirror 13 is rotatable around an axis of rotation that coincides here with the central longitudinal axis 8 of the pipe 2.

The vehicle 10 supports a powder distributing system 12. The powder distributing system 12 is configured for supplying powder 5 to the melting pool 4 to form a material layer 6 on the interior surface 1 of the hollow pipe 2.

For supplying the powder 5 to the melting pool 4, the powder distributing system 12 comprises a nozzle 14. Here, the nozzle 14 is arranged with respect to the mirror 13 such that the laser beam 3 is deflected past the nozzle 14, referring to the traveling direction of the laser, and turns to the melting pool 4.

The powder distributing system comprises a rotatably arranged member 15, in this case a disc shaped member 15. The nozzle 14 is mounted with the rotatably arranged member 15. Here the nozzle 14 is arranged at the outer circumference of the rotatably arranged member 15. Here, the powder distributing system comprises a plurality of nozzles 14 mutually arranged with the rotatably arranged member 15 for supplying powder 5 simultaneously and evenly along the length of the melting pool 4 in order to uniformly grow the material layer 6. Here, all of the plurality of nozzles 14 are arranged at the outer circumference of the rotatably arranged circular member 15. The powder is supplied to the powder distributing system through a main powder supply conduit 18. The rotatably arranged member 15 has a central cavity 19 for containing powder. This cavity 19 enables to buffer powder to cause a more even supply of powder to the nozzles 14.

The conduit 18 supplies the powder to the central cavity 19. Therefore, the conduit 18 enters the cavity 19 through a central opening 20. As is best shown in fig. 2, the rotatably arranged member 15 comprises a supply channel 16 for powder supply to the nozzle 14. The supply channel 16 has a supply channel length 1. The nozzle 14 has an outflow opening 17 where the powder 5 exits. The outflow opening 17 is arranged at an outflow radius r. The outflow opening 17 has an outflow diameter d. The supply channel length, the outflow radius and the outflow diameter are configured such that at a predetermined angular velocity of the rotatably arranged member 15, a uniform flow of powder 5 flows towards the melting pool 4. The supply channel or channels 16 transport the powder 5 from the cavity 19 tot the nozzle(s) 17.

The device 9 comprising a gas powered drive system (not shown) coupled with the powder distributing system 12 and the optical system 11 for rotating the rotatably arranged mirror 13 and the rotatably arranged member 15. Here, the rotatably arranged mirror 13 and the rotatably arranged member 15 are coupled such that they rotate in unity.

During use of the above described device, the following steps are performed.

Manipulating of a laser beam 3 over the interior surface 1 of the pipe 2 to form a line shaped melting pool 4. Meanwhile the pipe 2 is preferably maintained in a stationary position. Maintaining the pipe 2 in a stationary position is advantageous since these pipes typically may have a considerable weight and have a length of more than several meters.

At the same time, powder 5 is supplied to the melting pool 4 simultaneously and evenly along the entire length of the melting pool 4 in order to uniformly grow a material layer 6 on the interior surface 1 of the hollow pipe 2.

The laser beam is introduced into the interior 7 of the pipe 2. The laser beam 3 extends with respect to the longitudinal axis 8 as a center line of the pipe 2. The laser beam 3 is deflected towards the interior surface 1 of the pipe 2. Here, the laser is deflected by the mirror 11 at an included angle δ of about 35°. The laser beam 3 is focused on the interior surface 1 of the pipe 2.

In this case the melting pool 4 extends around the inner circumference of the pipe 2 to form a continuous annular shaped melting pool 4 or in other words circular shaped. The melting pool 4 extends transverse with respect to the longitudinal axis 8 of the pipe 2. The vehicle 10 is advanced through the pipe 2 to move the melting pool 4 along the longitudinal axis 8 of the pipe 2.

It will also be obvious after the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person which are within the scope of protection and the essence of this invention and which are obvious combinations of prior art techniques and the disclosure of this patent.

Claims

1. Method for laser cladding an interior surface (1) of a hollow open ended pipe (2), the method comprising;

- manipulating of a laser beam (3) over the interior surface of the pipe to form a melting pool that extends around the inner circumference of the pipe to form an continuous annular shaped melting pool, supplying powder (5) to the melting pool simultaneously and evenly along the entire length of the melting pool in order to uniformly grow a material layer (6) on the interior surface of the hollow pipe.

2. Method according to claim 1, wherein the manipulating of a laser beam

comprises;

- introducing the laser beam into the interior (7) of the pipe so that a

center line of the laser coincides with a longitudinal axis (8) of the pipe and,

deflecting the laser beam towards the interior surface of the pipe.

3. Method according to claim 1 or 2, wherein the deflecting the laser beam towards the interior surface of the pipe comprises deflecting the laser beam at an included angle δ of less than 90°.

4. Method according to claim 3, comprising deflecting the laser beam at an included angle δ of about 35°.

5. Method according to any of the preceding claims, wherein the manipulating a laser beam to form a melting pool comprises manipulating the laser beam to form a melting pool that extends around the inner circumference of the pipe to form an discontinuous annular shaped melting pool, wherein discontinuities of the melting pool are caused by switching the laser beam on and off.

6. Method according to any of the preceding claims, wherein the manipulating a laser beam to form a melting pool comprises manipulating the laser beam to form a melting pool that extends transverse with respect to the longitudinal axis of the pipe.

7. Method according to any of the preceding claims, further comprising

manipulating the laser to move the melting pool along the longitudinal the pipe.

8. Device (9) for laser cladding an interior surface of a hollow open ended pipe, the device comprising;

- a vehicle (10) for travelling along a longitudinal axis of the hollow pipe and supporting an optical system (11) and a powder distributing system (12),

wherein the optical system comprises means (13) for manipulating the laser beam over an interior surface of the pipe to form a melting pool that extends around the inner circumference of the pipe to form an continuous annular shaped melting pool, and

- the powder distributing system being configured for supplying powder to the melting pool simultaneously and evenly along the entire length of the melting pool in order to uniformly grow a material layer (6) on the interior surface of the hollow pipe.

9. Device according to claim 8, wherein the means for manipulating the laser beam comprises a movably arranged mirror (13).

10. Device according to claim 9, wherein the mirror is rotatably arrang

11. Device according to any preceding claim 8-10, wherein the powder distributing system comprises a nozzle (14) arranged with respect to the means for manipulating the laser beam such that the laser beam is deflected past the nozzle and turns to the melting pool.

12. Device according to any preceding claim 8-11, wherein the powder distributing system comprises a rotatably arranged member (15), and wherein the nozzle is mounted with the rotatably arranged member for supplying powder

simultaneously and evenly along the length of the melting pool in order to uniformly grow the material layer.

13. Device according to claim 12, wherein the rotatably arranged member

comprises a supply channel (16) for powder supply to the nozzle, wherein at least a section of the supply channel extends at an angle φ with respect to a radius r of the rotatably arranged member.

14. Device according to claim 13, wherein the supply channel has a supply channel length 1, the nozzle has an outflow opening (17) having an outflow diameter d, and wherein the supply channel length, the radius r of the rotatably arranged member, the angle φ and the outflow diameter are configured such that at a predetermined angular velocity of the rotatably arranged member, a uniform flow of powder flows towards the melting pool.

15. Device according to any preceding claim 8-14, wherein the powder distributing system comprises a plurality of nozzles mutually arranged for evenly supplying of powder along a length of the melting pool.

16. Device according to any preceding claim 12-15, comprising a gas powered drive system coupled with the powder distributing system and the means for manipulating the laser beam for rotating the rotatably arranged mirror and/or the rotatably arranged member.

17. Device according to any preceding claim 12-16, wherein the rotatably arranged mirror and the rotatably arranged member are coupled such that they rotate in unity.