Laser processing machine

Abstract

Laser processing machines, such as laser cutting machine (LM), including a work table receiving workpiece (W), and work arm (1) with a laser cutting head (2). Laser cutting head (2) includes nozzle receiving device (7) and nozzle (D). Via nozzle (D) laser beam (11) may be directed onto work piece (W). Machine (LM) includes main drives moving work arm (1) and/or the laser cutting head (2) on X-Y-Z axes to process work piece (W), as well as an alignment unit to adjust laser beam (11). An adjusting station (3) includes receiving unit (31) fixing nozzle (D) and/or the nozzle receiving device (7) during centering of nozzle (D). The alignment unit has head element (5B) in laser cutting head (2). Head element (5B) receives nozzle (D) and/or the nozzle receiving device (7) and is slidable in X-Y directions, via the main drives. Head element (5B) may be fixed in a selected position, within the laser cutting head (2), via clamping device (12) releasable during nozzle centering at adjusting station (3).

Claims

1. A laser processing machine comprising: a work arm; a laser cutting head mounted on said work arm; a nozzle receiver arranged in said work arm; a nozzle configured to pass a laser beam, said nozzle connected to said nozzle receiver; an alignment unit for adjusting the laser beam relative to said nozzle, said alignment unit including a head arrangement receiving said nozzle receiver; an upper head section in said head arrangement; a nozzle adjusting station, said nozzle adjusting station including a nozzle receiving unit configured to fix said nozzle against movement; said alignment unit including a releasable clamping device configured to controllably release said nozzle for relative movement relative to said work arm and said laser cutting head; laser head main drives operatively connected to controllably move said work arm and said laser cutting head relative to said nozzle when said nozzle receiving unit fixes said nozzle against movement and said clamping device releases said nozzle, said laser head main drives operatively connected to controllably move said work arm, said laser cutting head, and said nozzle for laser processing of workpieces; and, a lower head section in said head arrangement, said lower head section including a laterally-slidable head piece connected to said nozzle receiver.

2. The laser processing machine as claimed in claim 1, wherein: said head piece is a cylindrical-core piece connected to said nozzle receiver.

3. A laser processing machine as claimed in claim 1, further comprising: said lower head section including an exterior housing operatively connected to said work arm through said upper head section, for movement with said work arm.

4. A laser processing machine as claimed in claim 1, further comprising: said releasable clamping device including an annular piston, said annular piston being arranged in an axially-extending annular space and being moveable between, (a) a first position in which said annular piston fixes said laterally-slidable head piece, and (b) a second position in which said annular piston releases said laterally-slidable head piece.

5. A laser processing machine as claimed in claim 4, further comprising: said annular piston is pneumatically biased to said second position; and, at least one clamping surface is connected to said annular piston to release said laterally-slidable head piece in said second position.

6. A laser processing machine as claimed in claim 4, further comprising: said annular piston is spring-biased to said first position; and, at least one clamping surface is connected to said annular piston to clamp said laterally-slidable head piece in said first position.

7. A laser processing machine as claimed in claim 4, further comprising: said annular piston is pneumatically biased to said second position, and a first clamping surface is connected to said annular piston to release said laterally-slidable head piece in said second position; said annular piston is spring-biased to said first position, and a second clamping surface is connected to said annular piston to clamp said laterally-slidable head piece in said first position; and, an interior flange of said annular piston forms said first and second clamping surfaces.

8. A laser processing machine as claimed in claim 7, further comprising: said laterally-slidable head piece has an exterior flange, and said annular piston has an interior flange circumferentially spaced from said exterior flange.

9. A laser processing machine as claimed in claim 1, further comprising: said releasable clamping device includes a clamping unit; and, said clamping unit includes at least one spring unit.

10. A laser processing machine as claimed in claim 9, further comprising: said clamping unit includes three spring assemblies.

11. The laser processing machine as claimed in claim 1, wherein: said laterally-slidable head piece is arranged with a radial play having value in the range of 1.0 to 5.0 mm.

12. The laser processing machine as claimed in claim 1, wherein: said laterally-slidable head piece is integral with said nozzle receiver.

13. A laser processing machine as claimed in claim 1, further comprising: a work table for receiving material to be processed.

14. A laser processing machine as claimed in claim 1, further comprising: a camera system provided underneath said nozzle receiving unit of said nozzle adjusting station, said camera system having a target for laser beam, said camera system having a removable absorption plate, and said camera system having a camera.

15. A laser processing machine as claimed in claim 14, further comprising: an image processing unit operatively communicating with said camera to process laser penetration hole images.

16. A laser processing machine beam alignment system comprising: a work arm; a laser cutting head mounted on said work arm; a nozzle receiver arranged in said work arm; a nozzle configured to pass a laser beam, said nozzle connected to said nozzle receiver; an alignment unit for adjusting the laser beam relative to said nozzle, said alignment unit including a head arrangement receiving said nozzle receiver; an upper head section in said head arrangement; laser head main drives operatively connected to controllably move said work arm and said head arrangement in an X-Y coordinate space relative to said nozzle when said nozzle receiving unit fixes said nozzle against movement and said clamping device releases said nozzle, said laser head main drives operatively connected to controllably move said work arm, said laser cutting head, and said nozzle for laser processing of workpieces; a nozzle adjustment station disposed in the X-Y coordinate space, said nozzle adjustment station having a nozzle receiving unit fixing said nozzle against movement in the X-Y coordinate space; said alignment unit including a releasable clamping device configured to controllably release said head arrangement for controlled X-Y coordinate positioning alignment by said at least one main laser head drive, relative to said work arm and said nozzle fixed in said nozzle adjustment station; and a lower head section in said head arrangement, said lower head section including a laterally-slidable head piece connected to said nozzle receiver.

17. A laser processing machine beam alignment system as claimed in claim 16, further comprising: a laterally-slidable head piece included in said releasable clamping device; said releasable clamping device including an annular piston, said annular piston being arranged in an axially-extending annular space and being moveable between, (a) a first position in which said annular piston fixes said laterally-slidable head piece, and (b) a second position in which the said annular piston releases said laterally-slidable head piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below in more detail with reference to the enclosed drawings that illustrate a preferred exemplary version of the laser processing machine according to the invention, in which:

(2) FIG. 1 is a diagrammatic section view of a first version of a work arm with a cutting head of the laser processing machine according to the invention in an adjusting station;

(3) FIG. 2 is a cross section, shown in enlarged scale, of a part shown in FIG. 1;

(4) FIG. 3 is a diagrammatic view of a second exemplary version of the laser processing machine according to the invention in the adjusting station.

DETAILED DESCRIPTION

(5) FIG. 1 diagrammatically shows the first version, that is, a part of a work arm 1 of a laser processing machine LM according to the invention, with a laser cutting head 2 arranged in an adjusting station 3. Preferably the adjusting station 3 is arranged beside a cutting region of the machine LM (not shown), but still in an effective working region of main drives of the machine LM, e.g. on a known work table (not shown).

(6) The work arm 1 comprises, in the present version, known main laser head drives (not shown) with a central control system, preferably a CNC control system, which main drives are suitable for moving the work arm 1 together with the laser cutting head 2 according to the coordinates specified in each case (in the directions of the X-Y-Z axes) for processing a work piece W that has been affixed to the work table (e.g. in a manner described in EP-0680805B1, having counterpart U.S. Pat. No. 5,667,707A which is incorporated by reference, into the present disclosure).

(7) FIG. 1 shows a partial section view of the design and arrangement of the laser cutting head 2 according to the invention. In this version, the laser cutting head 2 has a split design; it comprises two parts, namely an upper head section 4 and a lower head section 5. The upper head section 4 is affixed to the work arm 1 so that it can move together with the work arm 1. In the upper head section 4 optical elements (not shown) of the laser cutting head 2 (lens, lens holder, mirror, etc.) are arranged in a known manner.

(8) However, the lower head section 5 has a special design according to the invention. Said lower head section 5 has a laterally displaceable head element and comprises an exterior housing 5A that is disconnectably connected to the upper head section 4, as well as a core piece 5B of annular design, which core piece 5B can be laterally displaced relative to the housing 5A for centering a nozzle D of the laser cutting head 2, and can be fixed after adjustment.

(9) So in this version, the core piece 5B forms the laterally displaceable head element mentioned in the introduction. In a central aperture 6 of the core piece 5B a cylindrical nozzle receiving device 7 is arranged which at its lower end comprises a thread connection 36 with the coaxial nozzle D (FIG. 1).

(10) In the lower head section 5, i.e. between the housing 5A and the core piece 5B, there is a cylindrical interior space 8 for the lateral relative adjustment of the core piece 5B (see FIGS. 1 and 2), together with the nozzle receiving device 7 and the nozzle D. In FIG. 1 the nozzle receiving device 7 is positionally attached in the aperture 6 of the core piece 5B by means of a union nut 9 that is connected to external threads 10 of the core piece 5B.

(11) Thus, according to the invention the mutual radial/lateral position of the core piece 5B can be adjusted together with the nozzle receiving device 7 and the nozzle D (in X-Y directions) relative to the housing 5A for centering the nozzle D, which guides a laser beam 11 through the laser cutting head 2, but without additional adjustment devices between the nozzle D and the work arm 1 (as is the case in the state of the art).

(12) A mirror (not shown) in the upper head section 4 is designed to reflect the laser beam 11 along an axis A-A, which laser beam 11 in a centered desired position comes in along the centre of the laser cutting head 2 and extends coaxially to a geometrical axis (designated by 35) of the nozzle D (see FIG. 1).

(13) On the one hand, to fix the core piece 5Btogether with the nozzle receiving device 7 and the nozzle Din its centered position, and on the other hand to release this affixation for a new centering/adjustment, according to the invention a special releasable clamping device 12 is provided. In the exemplary version, this clamping device 12 is arranged between the housing 5A and the core piece 5B and in this way it makes possible a relative X-Y displacement of the core piece 5B with the nozzle receiving device 7 and the nozzle D in the lower head section 5. However, this clamping device 12 is constructed in such a manner that the core piece 5B with the nozzle receiving device 7 and the nozzle D are fixed in the cutting head 2 during the normal cutting operation of the machine LM. This will be explained in more detail below with reference to FIG. 2.

(14) In FIG. 2, the details of the releasable clamping device 12 according to the invention are shown more clearly. This clamping device 12 makes possible, as explained above, predetermined relative X-Y displacement of the core piece 5B, together with the nozzle receiving device 7 and the nozzle D, in the lower head section 5 during the centering step. In this exemplary version the annular space 8 is formed between an exterior mantle surface 13 of the core piece 5B and an interior mantle surface 14 of the housing 5A in which, as an actuating unit 15 of the clamping device 12, preferably an annular piston 16 is arranged so as to be slidable in axial direction.

(15) In FIG. 2 the radial play of the movable core piece 5B is designated with the reference character 17, while the axial play of the annular piston 16 is designated with the reference character 18. The values of the plays or clearances 17 and 18 are preferably between 1.0 and 5.0 mm.

(16) In this version, a pneumatic working space 19 is provided in the annular space 15 underneath the annular piston 16. In this case, the annular piston 16 comprises a radial exterior flange 20 and a radial interior flange 21. A lower clamping surface 22 of the interior flange 21 is seated on an upper clamping surface 23 of a radial exterior flange 24 of the core piece 5B in the shown affixing home/basic position (see FIG. 2). The radial exterior flange 20 of the annular piston 16 interacts with an elastic clamping unit 25, which in this version comprises four spring assemblies 26. These spring assemblies 26 are preferably designed in the form of coaxial disc springs and are preferably arranged in the housing 5A beside the annular space 8 so as to be offset from each other by 90.

(17) This co-operation between the clamping unit 25 and the annular piston 16 consists of the lowermost spring element of the spring assemblies 26 (see FIG. 2) continuously pushing downwards an upper supporting surface 27 of the exterior flange 20 of the annular piston 16 and in this manner forcing the annular piston 16 into its lower home position shown in which the annular piston 16 jams, i.e. fixes, the core piece 5B, together with the nozzle receiving device 7 and the nozzle D, in its position by means of the clamping surfaces 22 and 23 in the lower head section 5.

(18) If the annular piston 16 is subjected to a pressure mediumin this case to compressed airthrough holes 28 and the working space 19, the annular piston 16 moves upwards in axial direction against the spring force of the spring assemblies 26 of the elastic clamping unit 25. In this way the clamping effect of the clamping unit 25 is thus determined.

(19) In this state, the mutual position of the core piece 5B, together with the nozzle receiving device 7 and the nozzle D, as well as of the housing 5A in the lower head section 5 (and also the position to the work arm 1, see FIG. 1) can be easily and reliably centered, between the nozzle D and the work arm 1, without any additional adjusting devices by means of the existing X-Y main drives of the machine LM.

(20) After blocking the flow of compressed air to the working space 19 the spring assemblies 26 press the annular piston 16 downwards again into its home position, in which the core piece 5B, together with the nozzle receiving device 7 and the nozzle D, is jammed or fixed again in its centered position by the clamping surfaces 22 and 23. In other words, this mechanism is constructed in such a manner that the movable part of the construction, i.e. in this version the core piece 5B of the lower head section 5, during normal cutting operation of the machine LM is fixed at all times.

(21) In a given case, according to the invention it is also possible to have such an inverse arrangement in which the laterally movable head element is formed by the housing 5A.

(22) Turning our attention once more to FIG. 1, the adjusting station 3 according to the invention is now described in more detail. As mentioned above, the adjusting station 3 is, for example, arranged beside a cutting region, but within the effective region of the present main drives (X-Y-Z) of the laser processing machine LM and is used as a receiving device and affixation device for the nozzle receiving device 7 during centering. To this effect the adjusting station 3 comprises a centering support 29 which is preferably affixed to a frame (not illustrated) beside the work table of the machine LM. In a recess 30 of the centering support 29 a receiving unit 31 is held and fixed.

(23) The receiving unit 31 is thus used as an adjusting unit and comprises a center hole 32 into which in the present case three rollers 33 partly reach in order to center and fix the inserted nozzle receiving device 7 in the adjusting station 3. The three centering rollers 33 are arranged circumferentially along the hole 32, preferably so as to be offset by 120 relative to each other.

(24) In FIG. 1 a hole of the nozzle D is designated by 34 and the geometrical axis of the nozzle is designated by 35, which in the centered state of the nozzle D is coaxial to the axis A-A of the laser beam 11. The above-mentioned thread connection between the nozzle D and the nozzle receiving device 7 is designated in FIG. 1 with reference number 36.

(25) The method of operation of the machine LM according to the invention according to FIGS. 1 and 2 is as follows:

(26) If the nozzle D is to be adjusted or centered, the laser cutting head 2 is moved, by means of normal adjustment of the work arm 1, to the determined position of the centering support 29 in the adjusting station 3. After this step, the clamping of the core piece 5B, together with the nozzle receiving device 7 and the nozzle D, is released. This means that the annular piston 16 of the clamping device 12 is subjected to compressed air through the holes 28, and then the annular piston 16 moves upwards in axial direction against the spring force of the elastic clamping unit 25. In this way the clamping effect of the clamping unit 25 is thus released.

(27) Thereafter the lower head section 5 can be moved downwards in the direction of the Z axis, wherein the movable core piece 5B of the lower head section 5 of the laser cutting head 2together with the nozzle receiving device 7 and the nozzle Din its released state is vertically moved to the nozzle receiving unit 31 of the centering support 29 of the adjusting station 3, where it is received and fixed.

(28) Any checking or adjusting the laser beam 11 can then most easily be carried out in such a manner that from below some plastic tape (not shown) is stuck onto the underside of the nozzle D so that the briefly switched-on laser beam 11 can penetrate it and forms a hole in it. The actual position of this hole thus formed in the plastic tape is in the simplest case visually confirmed by the operator. Thereafter the optical position of the laser beam 11 is determined manually or automatically.

(29) In another exemplary version of the invention the image of the hole is acquired by means of a camera module directed onto the stuck-on plastic tape (in a manner similar to that in EP-1,561,538) and is transferred as an image signal to a monitor (not shown) of the machine LM. The actual position of the hole (and indirectly also of the laser beam) is shown on the monitor preferably by means of a target.

(30) If applicable, the hole image of the laser beam 11 can be subjected to an image analysis and can be immediately evaluated in a computer-controlled manner or manually, and thereafter corresponding corrections of positioning are carried out. However, according to the invention, the determined offset of the optical position of the laser beam 11 is correspondingly corrected by means of the present main axes drives X and Y of the machine LM, or by means of the CNC control system. In this way the centering process of the laser beam 11 is completed.

(31) Since by means of this centering method the nozzle receiving device 7, together with the nozzle D and the core piece 5B, is fixed in the centering support 29 of the adjusting station 3, the housing 5A of the lower head section 5 can be correctly aligned/adjusted relative to the centre and to the geometrical axis 35 of the nozzle D by means of the main axes drives of the machine LM in the direction of the X-Y axes.

(32) Subsequently the core piece 5B, together with the set centered position of the nozzle receiving device 7 and of the nozzle D, is clamped again by activating the clamping device 12. After this step the entire laser cutting head 2 can be moved by the work arm 1, from the adjusting station 3 in the direction of the Z axis by means of the main drive. Thereafter the nozzle D is, and remains, reliably fixed in the adjusted and centered state.

(33) FIG. 3 diagrammatically shows a further exemplary version of the laser cutting machine LM according to the invention, in which the machine LM according to FIGS. 1 and 2 for the purpose of correctly aligning the laser beam 11 to the nozzle hole of the cutting nozzle D comprises an additional camera system 37 in the adjusting station 3.

(34) For this purpose, in a manner similar to that mentioned above, the nozzle D is locked in the receiving unit 31 of the adjusting station 3, and adjustment itself is accomplished by laterally sliding the remaining cutting head relative to the nozzle D, wherein for this purpose, however, it is necessary to release first the clamping device 12.

(35) In the version shown in FIG. 3 the camera system 37 of the adjusting station 3 comprises a target (target piece) 38 that is penetrated by means of a laser pulse (e.g. the target comprises a plastic film or a metal foil that is as thin as possible); an absorption plate 39 that can be moved away; a height-adjustable camera 40 associated with a known image processing unit 41 (not shown in further detail); a housing 42 that provides protection e.g. against dust.

(36) As shown in FIG. 3, the camera system 37, which comprises the target 38, the removable absorption plate 39 and the height-adjustable camera 40, is underneath the receiving unit 31 provided for fixing the nozzle D in the adjusting station 3. The camera 40 is associated with the image processing unit 41.

(37) Before the camera system 37 can be used, a calibration should be carried out: with the correctly adjusted nozzle D, a movement into the receiving unit 31 takes place to fix the nozzle; the target 38 is transported into one position; by means of a laser pulse a hole is made into the target 38; the absorption plate 39 is then moved away; the camera 40 acquires the hole and stores its position and size; this position is stored as zero in the system; the absorption plate 39 is moved back into place.

(38) Subsequently the adjustment method is carried out as follows on the laser cutting machine LM according to the invention, as shown in FIG. 3: a) the laser cutting head 2 first moves over the receiving unit 31 of the adjusting station 3; b) the clamping device 12 of the laser cutting head 2 is then released; c) the laser cutting head 2 is moved into the receiving unit 31 to fix the nozzle; d) the clamping device 12 of the laser cutting head 2 is locked; e) the target 38 is transported into a predetermined position; f) by means of a laser pulse a hole is made in the target 38; g) the absorption plate 39 is then moved away; h) the camera 40 acquires the size and position of the hole; i) the absorption plate 39 is moved back into place; j) the position of the hole is compared to the calibration values by means of the image processing unit 41; k) if the position of the penetration hole does not coincide with the calibration position, the clamping device 12 of the laser cutting head 2 is released and the error is corrected with the main drives of the machine LM in the CNC axes; the clamping device 12 of the laser cutting head 2 is then locked again; l) for control purposes the above-mentioned procedure can be repeated; m) the laser cutting head 2 is moved out of the receiving unit 31 of the adjusting station 3, and thereafter normal operation of the machine LM can commence.

(39) In a further version, the focal position can be determined. To this effect with various focal positions holes are made in the target, which after each firing is displaced by one working position. The camera evaluates the holes size. In the smallest hole the focus was in the target.

(40) The invention thus makes it possible to achieve a semi-automatic or fully automatic centering of the nozzle, for which, however, no additional servo-motors or other adjusting devices are necessary between the nozzle head and the work arm, as is the case in the state of the art. By the invention the adjustment and construction of the laser cutting machine is significantly facilitated. The solution according to the invention makes it possible, without much effort, to reliably detect any deviation of the position of the laser beam from the desired/predetermined value, and to carry out suitable, simple, fast and reproducible correction for centering.

(41) It should be emphasized that, within the scope of protection according to the enclosed claims, further embodiments of the laser processing machine according to the invention may be carried out, for which, knowing the present disclosure of the invention, a person having ordinary skill in the art would not, however, require any further technical teaching.

(42) For example, in the releasable clamping device 12 the annular piston 16 could also be operated hydraulically or electro-magnetically. The spring assemblies 26 could, if applicable, be replaced by a coil spring or other spring elements, e.g. pneumatic spring units. In a further embodiment option, the nozzle receiving device 7 and the core piece 5B could be designed as an integrated, preferably single-part element. In this way the construction of the cutting head 5 could be further simplified.

(43) The single annular piston 16 (of the versions shown) could, if applicable, be replaced by piston elements or piston segments that are arranged so as to be offset along the annular gap. Furthermore, such a design is also possible in which the machine LM comprises two or more laser cutting heads 2 (not illustrated).

(44) Of course, it is also feasible for a laser cutting machine to be provided without a work table. This can apply, for example, to mobile laser cutting machines and oversize work pieces where the laser cutting machine is moved towards the work piece, wherein the work piece is affixed elsewhere, or wherein as a result of its size and weight does not require any affixation at all.

LIST OF REFERENCE CHARACTERS

(45) A-AAxis of laser beam DNozzle LMLaser cutting machine WWork piece to be processed 1Work arm 2Laser cutting head 3Nozzle adjusting station 4Upper head section 5Lower head section 5AHousing 5BCore piece 6Aperture 7Nozzle receiving device 8Cylindrical interior space 9Union nut 10External threads 11Laser beam 12Releasable clamping device 13Exterior mantle surface (of the core piece) 14Interior mantle surface (of the housings) 15Actuating member 16Annular piston 17Radial play (of core piece) 18Axial play (of the piston) 19Working space 20Exterior flange 21Interior flange 22Lower clamping surface (of the interior flange) 23Upper clamping surface (of the exterior flange of the core piece) 24Exterior flange (of the core piece) 25Clamping unit 26Spring assembly 27Upper supporting surface (of the annular piston) 28Hole (for compressed air) 29Centering support 30Recess 31Nozzle receiving unit 32Cylindrical hole 33Centering roller 34Nozzle hole 35Geometrical axis of nozzle 36Thread connection 37Camera system 38Target 39Absorption area 40Camera 41Image processing unit 42Housing