DE102019203946A1 - Process for laser cutting as well as the associated laser processing machine and computer program product - Google Patents

Abstract

In a method for laser cutting a good part (13) from a particularly plate-shaped workpiece (2) by means of a good part cut (14) and for laser cutting a residual grid (15) surrounding the good part (13) into several residual grid parts (15a-15c) or one within the Good part (13) lying slug (18) into several slug parts (18a-18c) by means of several dividing cuts (16a, 16b), which open into or depart from the good part contour (24), the good part cut (14) is according to the invention into several good part partial cuts (14a-14c) divided. Beginning with a good part partial cut (14a), the good part partial cuts (14a-14c) and the dividing cuts (16a, 16b) are alternately carried out, with a good part partial cut beginning at the end of the previous good part partial cut and between the intersection points (17a, 17b) of the next and the next but one dividing cut (16a, 16b) with the good part contour (24) or between the intersection point (17b) of the last dividing cut (16b) with the good part contour (24) and the free cut point (F) of the good part ( 13) or Butzens (18) ends.

Description

The invention relates to a method for laser cutting a good part from a particularly plate-shaped workpiece by means of a good part cut and for laser cutting a residual lattice surrounding the good part into several remaining lattice parts or a slug lying within the good part into several slice parts by means of several dividing cuts which open into or depart from the good part contour .

When laser cutting of, in particular, plate-shaped materials, workpiece parts are often cut that have openings within their outer contour. These openings must be cut before the good part contour. The resulting waste parts (slugs) are - depending on their size - either ejected downwards from the process zone (by dropping them or by actively pressing them out, as shown in, for example DE 10 2016 208 872 A1 ) or remain in the scrap skeleton together with the good part and must be sorted manually or automatically from the cut workpiece sheet. From the prior art, e.g. from US 8716625 B2 or JPH 10244394 A, it is also known to divide waste parts into smaller pieces before cutting the good part contour, which can be ejected by dropping them.

For the reliable separation of laser-cut workpiece parts, it can also be helpful to partially cut off the scrap skeleton around a good part, i.e. cut into smaller pieces. This can enable a simplified removal of the good part, since the good part is prevented from getting caught in the scrap skeleton. This is particularly advantageous in laser cutting machines in which the workpiece is moved, since every good part must be removed immediately after the free cut and failure to remove it due to tilting or catching in the scrap skeleton can result in machine downtime and necessary intervention by the operator.

From JPH 09285886 A it is known, when cutting several good parts that have common separating cuts (common edges), first to largely cut the outer contour of all parts, then to make the common separating cuts and then to cut the last section of the outer contour. Out US 20050172764 A1 It is also known to define connecting paths between the parts when cutting several good parts in order to reduce the number of necessary grooves. The good part contour of the individual parts is divided into sub-areas for this purpose.

In contrast, the object of the present invention is to provide a method for laser cutting in which the slug or residual lattice parts adjoining the good part are divided and good parts are produced with high quality.

According to the invention, this object is achieved in that the good part cut is divided into several good part partial cuts and that, beginning with a good part partial cut, the good part partial cuts and the dividing cuts are carried out alternately, with a good part partial cut at the end of the previous good part Partial cut begins and ends between the intersection points of the next and the next but one dividing cut with the good part contour or between the intersection point of the last dividing cut with the good part contour and the free cut point of the good part or slug.

It was recognized that dividing cuts made before the good part cut interfere with the cutting process in the subsequent good part cut in such a way that a visible mark (discoloration, mark) remains. When laser cutting with an inert cutting gas such as Nitrogen, the heat flow in the melt cut and the discharge of the melt through the cutting gas are disturbed by the already made cutting cut. The heat dissipation and the effective gas pressure are reduced, so that the melt is no longer expelled sufficiently and / or the cutting edge becomes too hot. When laser cutting with oxygen, the processes in the chemical combustion process in the flame cut are also changed by the existing separating cut, which also has a detrimental effect on the edge quality of the good part.

According to the invention, the good part cut is therefore divided into several good part partial cuts in order to achieve good quality, with a good part partial cut in each case being cut first before an adjacent cutting cut, then the cutting cut is cut and then a return to the good part cut takes place. The dividing cuts for dividing the residual lattice or an inner slug are therefore made towards an already cut good part partial cut or away from an already cut good part partial cut. The good part cut is interrupted, a dividing cut is then carried out and then the good part cut is continued. According to the invention, a partial cut of good parts is carried out beyond the point of intersection with the next fragmentation cut so that the next partial cut of good parts can be continued from an existing cut gap that is “free of intersection” at the resumption point. The good part partial cut is so far beyond the crossing point continued that at the point of re-entry of the next good part partial cut, stable, predictable process conditions prevail, particularly with regard to the gas pressure, in spite of the existing, adjacent dividing cut gap.

In the cutting strategy according to the invention, it is essential that the good part partial cuts and the dividing cuts are made alternately in order to keep the distance between the end point of a good part partial cut and the adjacent dividing cut as small as possible.

Particularly preferably, a partial cut of a good part ends at most so far away from the intersection of the next dividing cut that no bending and / or heat distortion occur on the good part or on the slug. A good part partial cut preferably ends closer to the intersection of the next fragmentation cut than at the intersection of the next but one fragmentation cut or at the free cut point. If the good part partial cut is too long, the part of the good part or the slug that is no longer connected to the good part or the surrounding scrap skeleton is too large, and the good part or the slug can bend (especially with thin sheet metal) and / or a heat distortion of the good part or the slug (especially with higher sheet thicknesses) occurs. If this is the case, the point of intersection of the good part partial cut and the fragmentation cut and / or the re-entry point of the next good part partial cut in the previous good part partial cut are no longer correctly positioned, which in turn leads to a loss of quality on the cut edge of the good part.

Since bent or warped good or slug parts cannot be cut further correctly, in order to guarantee process reliability and the repeatability of the cuts, it must be ensured that at the time of the fragmentation cut the good part or the (remaining) slug part still has a strong bond with the surrounding scrap skeleton or good part possesses, so that the distance between the end point of an executed good part partial cut to the intersection point of the next fragmentation cut is not too great. On the other hand, the distance must be sufficiently long so that stable, predictable process conditions, especially with regard to the gas pressure, prevail at the beginning of the next good-part severing cut at the end of the previous good-part partial cut, despite the already existing dividing cut gap. Therefore, the distance between the end point of a completed partial cut and the crossing point of the next cut should be at least 2 mm.

In a preferred variant of the method it is provided that a dividing cut leading away from the good part begins at least at the kerf of the previously performed good part partial cut or a dividing cut leading to the good part ends at least at the kerf center of the previously performed good part partial cut. The cutting gap overlap of the dividing cut with the good part partial cut is therefore at least 50%. If the dividing cut leads to the good part, there is a somewhat higher tolerance with regard to fluctuations in the kerf overlap of the dividing cut and the good part partial cut. A fragmentation cut leading away from the good part requires an overlap of the kerf with the good part partial cut of advantageously more than 50%, and the fragmentation cut should be started with reduced laser power.

When dividing the scrap lattice or the slug, the dividing cuts are preferably selected so that they begin or end at changes of direction, corners or radii of the good part contour, since any slight re-entry marks on the good part edge at these points are not noticeable.

A good part partial cut to be carried out next preferably begins set back, in particular set back by only a few tenths of a mm, in the kerf of the previously carried out good part partial cut, so that the good part cut is cut further without piercing.

When dividing a slug, the distance between a cutting gas nozzle, from which a laser beam emerges together with a cutting gas, and the workpiece surface can advantageously be increased depending on the size of the slug and particularly preferably be at least 1.2 mm in order to avoid collisions between the cutting gas nozzle and to avoid a tilting slug part. When the cutting nozzle is raised, on the one hand the focus position of the laser beam is correspondingly lowered in opposite directions in order to achieve the same focus conditions as when cutting the good part partial cut, and on the other hand the gas pressure is increased by at least 25% compared to good part cutting.

When dividing slugs, the free cut point of a slug part should preferably not lie on the good part contour, but rather within the slug, for example in the middle of a fragmentation cut, since the cutting gas pressure then acts on the slug part at a more suitable point at the moment the slug part is cut free to achieve the most possible tilt-free falling of the slug part. The dividing cut is therefore preferably made in two partial cuts away from the good-part edge.

Before executing the first good part partial cut, internal slug parts which do not adhere to the good part contour are preferably first cut adjoin, cut out and then external slug parts, which adjoin the good part contour, cut out using the good part partial cuts and dividing cuts. In the case of larger slugs, which are, for example, significantly larger than the distance between two support webs or workpiece support tables or support slides, a grid can first be cut inside the slug. The resulting internal slugs can then be removed by dropping them or actively squeezing them out. Subsequently, partial areas of the good part contour are cut and the adjacent dividing cuts are extended towards the good part contour. When cutting the grid, it is essential that the puncture points of the laser beam lie within the slug and have a distance to the good part contour of at least 3 mm in order to avoid injection splashes on the good part contour. The spacing of the raster lines from one another preferably corresponds to at least half the outer diameter of the cutting nozzle used. In this way, collisions between the cutting nozzle and possibly tilting slug parts are avoided.

The invention also relates to a laser processing machine with a laser beam generator for generating a laser beam, with a laser processing head from which the laser beam emerges, and a workpiece support, both of which can be moved relative to one another, and with a machine control which is programmed to carry out the method according to the invention.

Finally, the invention also relates to a computer program product which has code means which are adapted to carry out all steps of the method according to the invention when the program runs on a machine control of a laser processing machine.

• 1 eine zum Durchführen des erfindungsgemäßen Verfahrens geeignete Laserbearbeitungsmaschine;
• 2a-2f die einzelnen Schritte beim erfindungsgemäßen Verfahren zum Laserschneiden eines Gutteils und eines Restgitters;
• 3 einen Gutteil-Teilschnitt und einen Zerteilungsschnitt im Bereich ihres Kreuzungspunkts entsprechend III in 2d;
• 4 eine Schnittführung beim erfindungsgemäßen Verfahren zum Laserschneiden eines innenliegenden Butzens aus einem Gutteil;
• 5 eine zu 4 modifizierte Schnittführung; und
• 6 ein Schnittraster zum zusätzlichen Ausschneiden von innenliegenden Butzenteilen

Further advantages and advantageous configurations of the subject matter of the invention emerge from the description, the claims and the drawings. The features mentioned above and those listed below can also be used individually or collectively in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for describing the invention. Show it:

• 1 a laser processing machine suitable for performing the method according to the invention;
• 2a-2f the individual steps in the inventive method for laser cutting a good part and a residual lattice;
• 3 a good part partial cut and a fragmentation cut in the area of their crossing point according to III in 2d ;
• 4th a cutting guide in the method according to the invention for laser cutting an inner slug from a good part;
• 5 one to 4th modified cut; and
• 6th a cutting grid for additional cutting out of internal slug parts

In the 1 Laser processing machine shown in perspective and schematically 1 is used for laser cutting of plate-shaped workpieces 2 . The laser processing machine 1 includes a cutting device 3 with a laser beam generator 4th to generate a laser beam 5 , an external beam guide 6th and a machining head 7th , as well as a work table 8th with a workpiece support 9 . The laser beam generator 4th can for example be designed as a CO ₂ , disk, fiber or diode laser. The laser beam 5 can either through a fiber optic cable or with the help of mirrors to the processing head 7th be guided. The processing head 7th has a processing nozzle 7a on from which the laser beam 5 emerges downwards together with a cutting gas. The processing head 7th is on a cross member 10 attached and in a plane parallel to the workpiece support 9 Can be moved in X and Y directions. The workpiece support 9 is through a variety of supports 11 formed with preferably triangular support point tips that form a support plane for the workpiece to be machined 2 define. The supports 11 are arranged in a predetermined grid. From the workpiece 2 Workpiece parts that have been cut free also lie on the supports 11 on. The laser processing machine 1 furthermore has a machine control 12th to control the movements of the machining head 7th and to control the laser beam generator 4th on.

2a-2f show the laser cutting of a good part 13 from a plate-shaped workpiece 2 by means of a good part cut 14th as well as dividing one of the good parts 12th surrounding skeleton 15th into several skeleton parts 15a-15c by means of two dividing cuts 16a , 16b , which in the good part contour shown in dashed lines 24 flow or depart from it. The good part cut to be carried out 14th is divided into several good part partial cuts 14a-14c divided up. Starting with the first good part partial cut 14a are the good part partial cuts 14a-14c and the dividing cuts 16a , 16b carried out alternately, with a good part partial cut beginning at the end of the previous good part partial cut and between the intersection points 17a , 17b the next and the next but one dividing cut 16a , 16b with the good part contour 24 or. between the crossing point 17b of the last cut 15b with the good part contour 24 and the clearance point F of the good part 13 ends. The dividing cuts preferably begin or end 16a , 16b at changes of direction, corners or radii of the good part contour 24 , since any slight re-entry marks on the good part edge are not noticeable at these points.

2a shows the workpiece 2 , in which the first good part partial cut 14a is cut ( 2 B) , about 2-5 mm above the crossing point 17a of the first cut 16a addition, so that when making the first dicing cut 16a on the good part 12th no contour damage or marks occur on the good part edge. Then the first cut is made 16a executed ( 2c ), the one at the intersection 17a begins or ends. Through the first cut 16a becomes the first part of the skeleton 15a severed. Then the second good part partial cut is made 14b cut ( 2d ), the one in the kerf of the first good part partial cut 14a begins and approx. 2-5 mm beyond the crossing point 17b of the second cut 16b out ends. Then the second dividing cut is made 16b executed ( 2e) who is at the crossing point 17b begins or ends. Through the second cut 16b becomes the second part of the skeleton 15b severed. Finally the third good part partial cut is made 14c cut ( 2f) , the one in the kerf of the second good part partial cut 14b begins and at the free intersection point F of the good part 13 ends, making the good part 13 cut free and the third scrap part 15c is separated.

3 shows the good part partial section 14a and the dividing cut 16a in the area of their crossing point 17a . The division cut 16a can from the middle of the kerf of the good part partial cut 14a can be started or at the middle of the kerf of the good part partial cut 14a end up. The cutting gap overlap of the dividing cut 16a with the good part partial cut 14a should advantageously be at least 50%. One of the good parts 13 The dividing cut leading away requires a high overlap of more than 50% with the existing kerf of the good part partial cut, and the dividing cut should be started with reduced laser power.

4th shows the cutting guide when laser cutting a good part 13 with one within the good part 13 lying slugs 18th through two fragmentation cuts 16a , 16b , which in the good part contour 24 run off and come off in three slugs 18a-18c is divided. The good part cut to be carried out 14th is divided into several good part partial cuts 14a-14c divided up. Starting with the first good part partial cut 14a are the good part partial cuts 14a-14c and the dividing cuts 16a , 16b carried out alternately, with a good part partial cut beginning at the end of the previous good part partial cut and between the intersection points 17a , 17b the next and the next but one dividing cut 16a , 16b or between the crossing point 17b of the last cut 16b and the free intersection point F of the slug 18th ends.

The first good part cut 14a starts inside the slug 18th at the puncture site 19th of the laser beam 5 and ends approx. 2-5 mm above the crossing point 17a of the first cut 16a out. The puncture site 19th lies within the slug 18th . Then the first cut is made 16a executed, for example at the intersection 17a begins and at another point of the first good part partial cut 14a ends. Through the first cut 16a becomes the first slug part 18a severed. Then the second good part partial cut is made 14b cut, the one in the kerf of the first good part partial cut 14a begins and approx. 2-5 mm beyond the crossing point 17b of the second cut 16b out ends. Then the second dividing cut is made 16b executed, for example at the intersection 17b begins and at another point of the first good part partial cut 14a ends. Through the second cut 16b becomes the second slug part 18b severed. Finally the third good part partial cut is made 14c cut, the one in the kerf of the second good part partial cut 14b begins and in the free intersection F of the slug 18th ends, making the third slug part 18c is cut free.

wobei s der Werkstückdicke entspricht. Der Abstand sollte mindestens 1,2 mm betragen. Beim Hochfahren der Schneiddüse 7a wird einerseits die Fokuslage des Laserstrahls 5 entsprechend gegenläufig abgesenkt, um gleiche Fokusbedingungen wie beim Schneiden des Gutteil-Teilschnitts zu erreichen, und andererseits der Gasdruck gegenüber dem Guteilschneiden um mindestens 25 % erhöht.When dividing the slug 18th can be the distance between the cutting gas nozzle 7a and the workpiece surface advantageously depending on the size of the slug parts 18a-18c increased to avoid collisions between the cutting gas nozzle 7a and to avoid a tilting slug part. The distance can be changed with the edge lengths L1 and L2 of the bitch 18th can be calculated as follows: $\text{distance}=\sqrt{\left(\mathrm{L.}{1}^2+\mathrm{L.}{2}^2\right)}-s,$

where s corresponds to the workpiece thickness. The distance should be at least 1.2 mm. When the cutting nozzle is raised 7a becomes on the one hand the focus position of the laser beam 5 accordingly lowered in opposite directions in order to achieve the same focus conditions as when cutting the good part partial cut, and on the other hand the gas pressure is increased by at least 25% compared to the good part cutting.

When dividing slugs 18th can do the dividing cuts 16a , 16b , different from in 4th shown, advantageously do not end at the good part contour, but rather as in 5 shown, lie approximately in the middle of the dividing cutting line, since then the cutting gas pressure at the moment the slug part is released acts at a more suitable point on the slug part in order to fall as tilt-free as possible of the slug part down to reach. The division cut is made for this purpose 16a , 16b away from the edge of the good part in two partial cuts 20th that meet in the middle of the division cutting line.

For larger slugs that are, for example, significantly larger than the distance between two supports 11 or two workpiece support tables or support carriages, as in 6th shown, first a grid 21st be cut by means of, for example, intersecting cuts at right angles, around internal slugs 22nd which do not conform to the good part contour 24 adjoin, cut free. These internal slugs 22nd can then be removed by dropping them or actively expressing them. The remaining, external slug parts, which are attached to the good part contour 24 are then cut using the good-part partial cuts and fragmentation cuts described above. When cutting the grid 21st should be the puncture points 23 a distance to the good part contour shown in dashed lines 24 of at least 3 mm. The spacing of the raster lines from one another preferably corresponds to at least half the outer diameter of the cutting nozzle used 7a . This way there will be collisions between the cutting nozzle 7a and if necessary tilting parts 22nd avoided.

The method according to the invention can be performed by the machine control 15th can be carried out in a controlled manner. The sequence program for machining the workpiece 2 , ie for controlling the implementation of the method according to the invention, can be created with an external programming system, ie with programming software that runs on a separate computer.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016208872 A1 [0002]
• US 8716625 B2 [0002]
• US 20050172764 A1 [0004]

Claims (13)

Method for laser cutting a good part (13) from a particularly plate-shaped workpiece (2) by means of a good part cut (14) and for laser cutting a residual grid (15) surrounding the good part (13) into several residual grid parts (15a-15c) or one within the good part ( 13) lying slug (18) into several slug parts (18a-18c) by means of several dividing cuts (16a, 16b) which open into or depart from the good part contour (24), characterized in that the good part cut (14) is divided into several good part partial cuts (14a-14c) is divided and that, beginning with a good part partial cut (14a), the good part partial cuts (14a-14c) and the dividing cuts (16a, 16b) are each carried out alternately, with a good part partial cut at the end of the previous good part partial cut begins and in each case between the intersection points (17a, 17b) of the next and the next but one dividing cut (16a, 16b) with the good part contour (24) or between the cross ngpunkt (17b) of the last dividing cut (16b) ends with the good part contour (24) and the free cut point (F) of the good part (13) or slug (18). Procedure according to Claim 1 , characterized in that a good part partial cut (14a-14c) ends closer to the intersection (17a) of the next fragmentation cut (16a) than at the intersection (17b) of the next but one fragmentation cut (16b) or at the free cut point (F). Procedure according to Claim 1 or 2 , characterized in that a good part partial cut (14a-14c) ends at most so far from the intersection (17a, 17b) of the next dividing cut (16a, 16b) that the good part (13) or slug (18) does not bend and / or no heat distortion occurs. Method according to one of the preceding claims, characterized in that a good part partial cut (14a-14c) ends at least 2 mm away from the intersection point (17a, 17b) of the next fragmentation cut (16a, 16b). Method according to one of the preceding claims, characterized in that a dividing cut (16a, 16b) leading away from the good part (13) begins at least at the cutting gap center of the previously executed good part partial cut (14a-14c) or a dividing cut (13) leading to the good part (13) 16a, 16b) ends at least at the middle of the kerf of the previously performed good part partial cut (14a-14c). Method according to one of the preceding claims, characterized in that the dividing cuts (16a, 16b) begin or end at changes of direction, corners or radii of the good part contour (24). Method according to one of the preceding claims, characterized in that a good part partial cut (14b, 14c) to be executed next begins set back in the kerf of the previously executed good part partial cut (14a, 14b). Method according to one of the preceding claims, characterized in that when dividing the slug (18), the distance between a cutting gas nozzle (7a), from which a laser beam (5) emerges together with a cutting gas, and the workpiece surface depends on the size of the slug parts (18a-18c) is increased and in particular is at least 1.2 mm. Method according to one of the preceding claims, characterized in that when the slug (18) is divided, the free cut point (F) of a slug part (18a-18c) does not lie on the good part contour (24). Method according to one of the preceding claims, characterized in that, before the first good part partial cut (14a) is carried out, first internal slug parts (22) which do not adjoin the good part contour (24) are cut out and then external slug parts which adjoin the good part contour ( 24), by means of which good part partial cuts (14a-14c) and dividing cuts (16a, 16b) are cut out. Procedure according to Claim 10 , characterized in that when the inner slug parts (22) are cut, the puncture points (23) of the laser beam (5) lie within the slug (18) and at least 3 mm from the good part contour (24). Laser processing machine (1) with a laser beam generator (4) for generating a laser beam (5), with a laser processing head (7) from which the laser beam (5) emerges, and a workpiece support (9), both of which can be moved relative to one another, and with a machine controller (12) which is programmed to carry out the method according to one of the preceding claims. Computer program product which has code means which are used to carry out all steps of the method according to one of the Claims 1 to 11 are adapted when the program runs on a machine control (12) of a laser processing machine (1).

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