Laser beam machine for thermally treating workpieces with a cable guidance system having a fitted deflection unit

Abstract

A laser beam machine has a laser head (3) for emitting a laser beam onto a workpiece which is to be treated, and a movement unit (1, 2, 9) for physically moving the laser head (3), which movement unit has a linearly moving machine portal (1) and a transverse carriage (2) which is held such that it can be moved on said machine portal in a transverse manner, wherein a flexible fiber cable (10) with a minimum permissible bending radius enters at an inlet point on the upper laser head end for transmitting the laser beam, and wherein a cable guidance system (12, 13) is provided in order to guide the fiber cable (10) at least over a portion of its length. In order to provide a laser beam machine proceeding from the above, in which laser beam machine inclined positions of the laser head (3) are also possible without the fiber cable (10) being subjected to excessive loading, the invention proposes that the cable guidance system (12, 13) has a deflection unit (13) which is fitted to the laser head (3) and which prespecifies a flexurally rigid deflection arc which extends above the inlet point and closely adjoins the inlet point, and by means of which deflection arc the fiber cable (10) is guided to the inlet point, and the radius of which deflection arc is greater than the minimum permissible bending radius of the fiber cable (10).

Claims

1. A laser beam emitting machine comprising: a laser head emitting a laser beam onto a workpiece that is to be treated, a movement unit spatially moving the laser head, movement unit having a linearly moving machine portal on which a transverse carriage is supported such that said carriage can be moved transversely, and the laser head being mounted on said carriage, a flexible fiber cable with a minimum permissible bending radius, said fiber cable transmitting the laser beam to the laser head and entering therein at an inlet point on an upper laser head end thereof, and a cable guidance system guiding the fiber cable at least over a portion of a length thereof, wherein the cable guidance system has a deflection unit that is mounted on the laser head and that predetermines a rigid deflection curve that extends above the inlet point and adjacent to the inlet point, and guides the fiber cable to the inlet point, and has a radius that is greater than the minimum permissible bending radius of the fiber cable.

2. The laser beam machine according to claim 1, wherein the fiber cable enters the deflection curve at a first contact point spaced from the laser head and extends downwards from the deflection curve to the inlet point at a second contact point close to the laser head.

3. The laser beam machine according to claim 2, wherein the deflection curve has a radius in a range of 100 to 150 mm.

4. The laser beam machine according to claim 2, wherein a distance between the first contact point remote from the laser head and a laser-head longitudinal axis extending through the inlet point is smaller than a diameter of the deflection curve.

5. The laser beam machine according to claim 1, wherein the deflection unit comprises a bracket and an adapter that is fixed via the bracket to the laser head and connects the deflection curve to a protective tube on the fiber cable.

6. The laser beam machine according to claim 5, wherein the bracket has a bracket center axis that with a laser-head longitudinal axis encloses an angle of less than 30 degrees.

7. The laser beam machine according to claim 5, wherein the protective tube extends sectionwise within a movement space defined between the machine portal and the laser head, wherein the protective tube is connected with an end thereof to the adapter and with another end thereof to the transverse carriage.

8. The laser beam machine according to claim 5, wherein the protective tube is a flexible ribbed tube of metal and the deflection curve is of aluminum or a carbon fiber-reinforced material.

9. The laser beam machine according to claim 1, wherein the deflection curve has a wall that is configured to be sectionwise tubularly closed and/or sectionwise in cross section in the form of a shell.

Description

EMBODIMENT

(1) The invention will now be described in more detail with reference to an embodiment and drawings. In a schematic illustration,

(2) FIG. 1 shows an embodiment of the laser beam machine according to the invention with a positioning unit and a deflection unit in a three-dimensional view,

(3) FIG. 2 shows a section of the laser beam machine with the deflection unit in an enlarged three-dimensional illustration, and

(4) FIG. 3 shows the deflection unit in a front view on the laser beam.

(5) The laser beam machine according to the invention is a laser cutting machine in the embodiment and the laser head is configured as a laser cutting torch 3. The laser cutting torch 3 is composed of a beam supply unit 27 and the adjoining laser cutting head 24 proper.

(6) FIG. 1 gives a survey of the movement unit of the laser cutting machine and the supply for the fiber cable to the laser cutting torch 3.

(7) The basic components and functions of the movement unit are known from DE 10 2012 008 122 A1. It comprises a machine portal 1 and a transverse carriage 2 on which the laser cutting torch 3 is mounted. Machine portal 1 and transverse carriage 2 are movable along the two linear axes 5, 6 which are orthogonal to each other. The laser cutting torch 3 is movable independently thereof by means of a linear guidance system 9 with a displacement kinematics along the displacement axes 7 and 8 (directional arrows 7; 8) in two spatial directions. Along the lift axis 7 the laser cutting torch 3 can be lifted or lowered for adjusting the height. The displacement axis 8 extends in parallel with the linear axis 5 (directional arrows) of the movement unit and is thus redundant thereto. Both displacement axes 7; 8 extend perpendicular to the linear axis 6, so that small movements of the laser cutting torch 3 can be performed in the direction of the redundant axes 5 by the linear guide system via a displacement along the displacement axis 8. Great movements of the laser cutting torch 3 along said axis are assumed by the machine portal 1.

(8) The laser cutting machine has an ytterbium fiber laser (not shown in the figure). The ytterbium fiber laser emits radiation of a working wavelength of about 1070 nm with a high laser power (several kW). The laser beam is guided via a fiber cable 10 to the laser cutting torch 3. The fiber cable 10 is configured as a flexible optical individual fiber which is provided with a plastic covering for protection against mechanical load. The free minimal bending radius of the fiber cable upon dynamic load is specified to be 200 mm.

(9) The fiber cable 10 passes via an energy chain 11, which is mounted on the transverse carriage 2, downwards into a movement space 14 in which the laser cutting torch 3 and the workpiece to be treated (not shown) are also positioned. On this cable section the fiber cable 10 is covered by a protective tube 12 of metal with corrugated profile for additional mechanical protection and is supplied in an arc to a deflection unit 13, which shall be explained in more detail hereinafter with reference to FIG. 2. To achieve a movement of the fiber cable 10 within the movement space that is as minimal as possible, the cable is guided as close as possible along the tool axis. The energy chain 11 is therefore arranged such that one leg is fixed to the transverse carriage 2 and the other leg is fixed to the linear guidance system 9 of the movement unit of the laser head. The energy chain 11 thereby performs the movements of the laser head not only in the vertical (z-direction) and the movement direction of the transverse carriage 2 (y-direction), but also in x-direction. The laying length of the fiber cable 10 in the movement space 14 can thereby be kept short and the fiber cable can be guided as close as possible along the tool axis.

(10) FIG. 2 shows the linear guidance system 9 on an enlarged scale. It has a biaxially serial displacement kinematics which allows a displacement of the laser cutting torch 3 along the displacement axes 7 and 8. A telescopic unit 22 which is configured in the manner of a drawer that is displaceable via a drive 23 is provided for a movement along the displacement axis 8. At its distal end the drawer is fork-shaped and forms a pivot joint for the laser cutting head 24. In addition, two struts 31a, 31b of invariable length are connected to the laser cutting head 24 via ball joints. The struts 31a, 31b are movably supported along slide axes by means of slides 32; 32b, each of which has a drive. The slide axes enclose an angle of 53? with each other and generate a plane which extends tilted by an angle of 36? relative to the displacement direction 8.

(11) The tool center point is the focus of the laser beam which is normally positioned on the surface of the workpiece to be treated or slightly thereunder. Upon change of the orientation of the laser cutting head 24 the tool center point can be held in an approximately spatially fixed manner, assisted by the linear guidance system.

(12) To avoid a collision with the linear guidance system upon tilting of the laser cutting head 24 in the direction of the bearing arrangement, the laser cutting torch 3 comprises a beam deflection unit 26 which guides the laser beam to the laser cutting head 24. A beam supply axis 28 extends through the beam deflection unit 26 and, offset thereto, a tool symmetry axis 25 through the laser cutting head 24 (symmetry axis of the laser cutting head). This offset arrangement results in a smaller extension of the laser cutting head 24 in the direction of the symmetry axis of the laser cutting head and in a reduced space requirement of the laser cutting head 24. As a result, the laser cutting head 24 can pass into the indentation 33 upon tilting, which on the whole allows a great tilt angle and a large work area for the laser cutting head 24.

(13) The great freedom of movement of the laser cutting head 24 is promoted according to the invention by a special way of the supply of the fiber cable 10 by using a deflection unit 13, which shall be explained in more detail hereinafter.

(14) The deflection unit 13 comprises a metallic holding bracket 131 which is fastened to the laser cutting torch 3, a metallic adapter 132 which is held by the holding bracket, and a deflection bow 133 of carbon fiber-reinforced material. It consists essentially of two bent side cheeks which are interconnected via webs on the underside. The side cheeks have a wall thickness of 2 mm. The deflection bow 133 is so rigid that in view of the normally occurring mechanical loads it ensures the constructionally predetermined bending radius of 150 mm. The adapter 132 is provided at its lower end with a receptacle for the protective tube 12 and at its upper end with a receptacle for the deflection bow 133.

(15) The holding bracket 131 extends at an acute angle from the laser cutting head 24 obliquely upwards, as shall be explained in further detail with reference to FIG. 3. The fiber cable 10 is guided out of the protective tube 12 via the adapter 132 over the static deflection bow 133 and from there in an almost straight line to an inlet point 35 of the beam supply unit 27. Due to the connection to the laser cutting head 24 the deflection unit 13 also performs all movements of the laser cutting head 24 within the space without the shape of the deflection bow 133 being changed thereby.

(16) The lateral cheeks of the deflection bow 133 guide the fiber cable 10 and protect it against mechanical damage. The upper outlet end of the deflection bow 133 closely adjoins the inlet point 35 of the fiber cable 10 into the beam supply unit 27 in the sense that after departure from the deflection bow 133 it extends almost in a straight line to the inlet point 35.

(17) Due to the co-moved and constructionally statically predetermined deflection bow 133 the position of the fiber cable 10 up to the inlet point 35 is mechanically stabilized, namely also upon tilting of the laser cutting head 24 relative to the vertical. Centrifugal forces caused by fast directional changes of the laser cutting head 3 are barred from the fiber cable 10 and removed by the deflection unit 13.

(18) Moreover, the bending radius predetermined by the mechanical rigid deflection bow 133 can be made much smaller in the embodiment 150 mm than the bending radius which must be conceded to the fiber cable in the case of free arc formation (at least 200 mm are here standard). Since the smaller bending radius is less extensive laterally, it requires less space and allows a more compact construction. Specifically, it is subjected to a smaller centrifugal acceleration upon directional changes or rotation of the laser cutting head 24 than would be the case with a free fiber-cable arc with a larger lateral extension. In this respect, too, the forces acting on the fiber cable 10 are kept small.

(19) The fiber cable 10 impinges at a contact point 134 remote from the laser cutting head (this is the inlet point into the deflection bow 133; in FIG. 2, it is concealed by the wall of the deflection bow 133) on the deflection bow 133 and extends at a contact point 136 close to the laser cutting head (this is the outlet point out of the deflection bow 133) from the deflection point 133 to the inlet point 35 of the fiber cable almost in a straight line downwards.

(20) FIG. 3 is a front view on the laser cutting torch 3, the bent laser cutting head 24 and the deflection unit 13. In this view the beam supply axis 28 and the tool symmetry axis 25 extend one after the other.

(21) The fiber cable 10 is guided around the deflection bow 133 up to the contact point 136 close to the laser cutting head, at which it leaves the deflection bow again. The fiber cable 10 describes a three-quarter circle around the deflection bow 133 from the deflection-arc inlet point 134 up to the outlet point 136.

(22) The center axis 135 of the holding bracket 131 encloses an acute angle ? of less than 30 degrees with said axes 25; 28. The deflection bow 133 has a diameter of 230 mm (radius: 115 mm) and is arranged as close as possible to the axes 25 and 28. This manifests itself in that the distance A between the axes 25, 28 and the contact point 134 remote from the laser cutting head is smaller than the diameter of the deflection bow 133. The distance is 200 mm in the embodiment.

(23) Hence, the fiber cable 10 impinges on the deflection bow 133 at the deflection-arc inlet point 134 which is not at a maximum distance from the laser cutting head 24. Since the fiber cable 10 impinges on the deflection bow 133 at a point closer to the laser cutting head 24, the fiber cable 10 and the protective tube 12 are guided as close as possible to the axes 25; 28 of the laser cutting head 24 and the pivot point of the tool axis (C-axis). As a result, the fiber cable 10 is subjected to smaller mechanical loads caused by centrifugal forces upon fast motional changes and to a small torsion upon rotation of the laser cutting head 24.