BEAM-FORMING UNITS WITH COOLING SYSTEMS FOR HIGH-POWER LASERS

Abstract

A beam-forming unit for forming a laser beam and focusing the laser beam onto a workpiece, the unit including a movable component, an immovable component, and a cooling system configured for movement of a cooling medium to actively cool the movable component, wherein the cooling system has a cooling water circuit on the immovable component configured for water cooling of the immovable component and the cooling medium, and wherein the cooling system is within an outer housing of that is sealed from the environment.

Claims

1. A beam-forming unit for forming a laser beam and focusing the laser beam onto a workpiece, the beam-forming unit comprising: a movable component; an immovable component; and a cooling system configured for forced movement of a cooling medium to actively cool the movable component, wherein the cooling system has a cooling water circuit arranged on or within the immovable component for water cooling of the immovable component and of the cooling medium, and wherein the cooling system is arranged within an outer housing that is sealed from the environment.

2. The beam-forming unit of claim 1, further comprising a highly reflective coating on at least a portion of the beam-forming unit to reduce heating of the beam-forming unit.

3. The beam-forming unit of claim 2, wherein the movable component is coated with the highly reflective coating.

4. The beam-forming unit of claim 1, wherein the cooling system has a fan for one or both of forced-air and gas cooling of the movable component.

5. The beam-forming unit of claim 4, further comprising an inner housing in which the movable component is arranged.

6. The beam-forming unit of claim 5, wherein the inner housing has a through passage on which the fan is arranged.

7. The beam-forming unit of claim 1, further comprising a bellows on the movable component configured to shield an interior of the movable component from the moving cooling medium.

8. The beam-forming unit of claim 7, wherein the immovable component at least partially forms an inner housing.

9. The beam-forming unit of claim 1, further comprising at least one radiation absorbent surface on the immovable component.

10. The beam-forming unit of claim 9, wherein the immovable component with the radiation absorbent surface is cylindrical in its interior and directly surrounds the laser beam.

11. The beam-forming unit of claim 10, further comprising a bellows on the movable component configured to shield an interior of the movable component from the moving cooling medium, wherein the immovable component is connected to the movable component via the bellows.

12. A laser processing machine comprising: a beam-forming unit for forming a laser beam and focusing the laser beam onto a workpiece, the beam-forming unit comprising: a movable component; an immovable component; and a cooling system configured for forced movement of a cooling medium to actively cool the movable component, wherein the cooling system has a cooling water circuit arranged on or within the immovable component for water cooling of the immovable component and of the cooling medium, and wherein the cooling system is arranged within an outer housing that is sealed from the environment.

Description

DESCRIPTION OF DRAWINGS

[0031] Additional features and advantages can be found in the following detailed description, in claims and the drawings. The various features can each be implemented in isolation or together in any desired combinations in variants of the invention. The features shown in the drawings are presented such that the particularities of the invention can be made clearly visible.

[0032] FIG. 1 is a perspective view of a laser processing machine with a beam-forming unit.

[0033] FIG. 2 is a first cross section through the beam-forming unit of FIG. 1.

[0034] FIG. 3 is a second cross section through the beam-forming unit of FIG. 1.

DETAILED DESCRIPTION

[0035] FIG. 1 is by way of example a perspective view of a laser processing machine 10. The laser processing machine 10 shown has, for example, a CO.sub.2 laser, diode laser or solid-state laser as the laser beam generator 12, a beam-forming unit 14 that can be moved in the X and Y directions (such as a laser machining head), and a workpiece support 16. In the laser beam generator 12, a laser beam 18 is generated, which is guided by a (not shown) fiber-optic cable or (not shown) deflecting mirrors from the laser beam generator 12 to the machining head or to the beam-forming unit 14. A plate-shaped workpiece 20 is arranged on the workpiece support 16. The laser beam 18 is directed onto the workpiece 20 by focusing optics arranged in the machining head 14. The laser processing machine 10 (e.g., a laser cutting machine and/or laser welding machine) is also supplied with process gases 22, for example oxygen and/or nitrogen. The use of the respective process gas 22 is dependent on the machining process, workpiece material and quality requirements for the cutting edges or welding seams. Furthermore, a suction device 24 is present, which is connected to a suction channel 26 located below the workpiece support 4. The process gas 22 is supplied to a process gas nozzle, such as a cutting gas nozzle 28 of the machining head 14, from which it emerges together with the laser beam 18. The laser processing machine 10 also has a machine control unit 30.

[0036] FIG. 2 is a cross section through the beam-forming unit 14, being a laser machining head for forming a laser beam and for collimation and focusing a laser beam onto a workpiece 20. The beam-forming unit 14 has an outer housing 32 and an inner housing 34. The inner housing 34 is within the outer housing 32. Parts of the inner housing 34 are immovable components, three of which are exemplified by 36a, 36b, 36c. First and second movable components 40a, 40b are attached to the immovable components 36a, 36b, 36c via bellows, one of which is denoted by 42 here by way of example. The movable components 40a, 40b are respectively formed as a lens mount for a collimating lens 44a and a focusing lens 44b. The movable components 40a, 40b are moved by motors 46a, 46b and threaded rods 48a, 48b parallel to the direction of the longitudinal axis 50 of the beam-forming unit 14 or the optical axis. The movable and immovable components 36a, 36b, 36c, 40a, 40b form an interior cylindrical tube 52. The laser beam 18 passes through the cylindrical tube 52 from an inlet 56a to an outlet 56b at which a process gas nozzle (not shown) can be arranged.

[0037] A cooling system 58 of the beam-forming unit 14 has cooling plates, two of which are denoted by 60a, 60b here by way of example, of a cooling water circuit 62. The cooling plates 60a, 60b are attached to the outside of the inner housing 34. Cooling water enters each cooling plate 60a, 60b through an input, for example input 64a, in the form of an input current 66a into the cooling plate, for example cooling plate 60a, and exits through an output, for example output 64b, in the form of an output current 66b from the respective cooling plate, for example cooling plate 60b. Thereby, the cooling plates 60a, 60b can be connected to one another by fluidic connections (not shown) for transporting the cooling water.

[0038] FIG. 3 is a cross section through the beam-forming unit 14 with a switched-on fan 68 as part of the cooling system 58. The cooling system 58 can include a plurality of fans 68 at different locations of the beam-forming unit 14. The fan 68 is located outside the inner housing 34 at an entrance recessed passage 70a of the inner housing 34 in front of the first movable component 40a. An air flow 74 is sucked in by the fan 68 and conveyed to the first movable component 40a for cooling. The air is guided around the first movable component 40a and exits the inner housing 34 on the opposite side through an exit recessed passage (through bore) 70b. The bellows 42 prevents entry of air into the cylindrical tube 52 and into the interior of the first movable component 40a. The air is sucked in by the fan 68 and thereby guided around the inner housing 34 after exiting the exit recessed passage (through bore) 70b and is guided past the cooling water circuit 62 attached to the inner housing 34. This cools the air before it is returned to the movable component 40a in the interior of the inner housing 34 by the fan 68. The immovable components 36a, 36b, 36c have at least partial laser radiation absorbent surfaces on their radially inner surfaces, which are indicated by double dashed lines, and one of which is denoted by 38 here by way of example. The radiation absorbent surfaces can be produced for example by black chrome plating, anodizing, powder coating, spraying graphite lacquer, or by surface treatment of the immovable components 36a, 36b, 36c with laser radiation. The movable components 40a, 40b each have a coating that reflects laser radiation, one of which is denoted by 72 here with small light flashes by way of example, on its radially inner surface to reduce heating of the movable components 40a, 40b by scattered laser radiation. This coating can be, for example, gold or a gold alloy (e.g., AuCo0.2).

[0039] In general, the beam-forming unit 14 for focusing a laser beam 18 onto a workpiece 20 for laser machining includes a cooling system 58 that can actively drive the flow of a cooling medium. The beam-forming unit 14 can be at least partially coated with a coating 72 configured for reflecting the laser beam 18 to reduce heating of the beam-forming unit 14. The beam-forming unit 14 can have an outer housing 32. An immovable component 36a, 36b, 36c can be immovably arranged or formed relative to the outer housing 32. A movable component 40a, 40b may be movably arranged or formed relative to the immovable component 36a, 36b, 36c. The movable component 40a, 40b can have a reflective interior and the immovable component 36a, 36b, 36c an radiation absorbent interior coating. The movable component 40a, 40b can be cooled by a fan and/or the immovable component 36a, 36b, 36c by flow-through cooling plates 60a, 60b.

OTHER EMBODIMENTS

[0040] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

LIST OF REFERENCE SIGNS

[0041] 10 Laser processing machine [0042] 12 Laser beam generator [0043] 14 Beam-forming unit/Laser machining head [0044] 16 Workpiece support [0045] 18 Laser beam [0046] 20 Workpiece [0047] 22 Process gases [0048] 24 Suction device [0049] 26 Suction channel [0050] 28 Cutting gas nozzle [0051] 30 Machine control unit [0052] 32 Outer housing [0053] 34 Inner housing [0054] 36a, b, c Immovable components [0055] 38 Radiation absorbent coatings [0056] 40a, b Movable components [0057] 42 Bellows [0058] 44a Collimating lens [0059] 44b Focusing lens [0060] 46 Motors [0061] 48 Threaded rods [0062] 50 Longitudinal axis [0063] 52 Cylindrical tube [0064] 56a, b Inlet, outlet tube [0065] 58 Cooling system [0066] 60a, b Cooling plates [0067] 62 Cooling water circuit [0068] 64a, b Input, output cooling plate [0069] 66a, b Input current, output current [0070] 68 Fan [0071] 70a, b Entrance/exit recessed passage (through bore) of the inner housing [0072] 72 Reflective coating [0073] 74 Air flow