# US 11,440,141 B2 · Devices and methods for monitoring, in particular for regulating, a cutting process

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- Number: US 11,440,141 B2
- Document ID: US11440141B2
- Status: Granted
- Kind: B2
- Application number: 16/545,273
- Filed: 2019-08-20
- Published: 2019-12-12
- Granted: 2022-09-13
- Earliest claimed: 2013-09-13
- Assignees: TRUMPF Werkzeugmaschinen GmbH + Co. KG
- Applicants: TRUMPF Werkzeugmaschinen GmbH + Co. KG
- Inventors: Boris Regaard; David Schindhelm
- Web page: https://patentgrep.com/patent/US11440141B2

## CPC

- B23K 26/032: {using optical means}
- B23K 26/38: by boring or cutting
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM

## Abstract

The invention relates to devices and methods for monitoring or regulating a cutting process on a workpiece. A focusing element focuses a high-energy beam onto the workpiece. An image capture apparatus captures a region at the workpiece to be monitored. The region includes an interaction region of the high-energy beam with the workpiece. An control apparatus determines at least one characteristic variable of the cutting process, in particular of a kerf formed during the cutting process, on the basis of the captured interaction region.

## Claims

### Claim 1

A device for monitoring a cutting process on a workpiece comprising:
a focusing element for focusing a high-energy beam onto the workpiece;
an image capture apparatus for capturing a region at the workpiece to be monitored, the region comprising an interaction region of the high-energy beam with the workpiece,
wherein the image capture apparatus forms an observation beam for observing the interaction region from an observation direction extending at an angle to a beam axis of the high-energy beam in a convergent beam path between the focusing element and the workpiece, and
wherein the image capture apparatus comprises an imaging optic system configured to generate an image of the interaction region from along the observation beam, wherein the image capture apparatus has a stop for modifying an alignment of the observation direction of the observation beam; and
a control apparatus configured to modify the alignment of the observation direction in a projection into a plane perpendicular to the beam axis in a manner dependent on an advance direction of the cutting process.

### Claim 2 (depends on 1)

The device of claim 1, wherein the high-energy beam is a laser beam.

### Claim 3 (depends on 1)

The device of claim 1, wherein the image capture apparatus is configured to modify the alignment of the observation direction of the observation beam in a plane perpendicular to the beam axis of the high-energy beam.

### Claim 4 (depends on 3)

The device of claim 3, wherein the image capture apparatus has a stop for modifying the alignment of the observation direction of the observation beam.

### Claim 5 (depends on 1)

The device of claim 1, wherein the imaging optic system is configured to generate a plurality of images of the interaction region from differently aligned observation directions.

### Claim 6 (depends on 5)

The device of claim 5, wherein the imaging optic system has a plurality of imaging optical elements for generating the plurality of images.

### Claim 7 (depends on 6)

The device of claim 6, wherein the plurality of imaging optical elements form a grid arrangement.

### Claim 8 (depends on 5)

The device of claim 5, wherein, for the purposes of generating the plurality of images, the imaging optic system has an apparatus configured to form a respective observation beam by influencing a beam direction of an observation beam path.

### Claim 9 (depends on 1)

The device of claim 1, further comprising a control apparatus configured to modify the alignment of the observation direction in a plane perpendicular to the beam axis in a manner dependent on an advance direction of the cutting process.

### Claim 10 (depends on 8)

The device of claim 8, wherein the control apparatus is configured to keep the alignment of the observation direction constant relative to the advance direction.

### Claim 11 (depends on 1)

The device of claim 1, wherein the observation direction extends counter to an advance direction of the cutting process in a plane perpendicular to the beam axis of the high-energy beam.

### Claim 12 (depends on 11)

The device of claim 11, wherein the control apparatus is configured to determine one or more of a cutting front angle of the kerf, an overshoot of a predetermined cutting front angle of the kerf, and an undershoot of the predetermined cutting front angle of the kerf as the at least one characteristic variable of the kerf on the basis of the captured interaction region.

### Claim 13 (depends on 11)

The device of claim 11, wherein the angle at which the observation direction extends in relation to the beam axis of the high-energy beam deviates by less than 5° from the predetermined cutting front angle.

### Claim 14 (depends on 12)

The device of claim 12, wherein the angle at which the observation direction extends in relation to the beam axis of the high-energy beam deviates by less than 2° from the predetermined cutting front angle.

### Claim 15 (depends on 1)

The device of claim 1, wherein the angle from the observation direction to the beam axis of the high-energy beam is in the range of 5°-15°.

### Claim 16 (depends on 1)

The device of claim 1, wherein the angle from the observation direction to the beam axis of the high-energy beam is in the range of 5°-10°.

### Claim 17 (depends on 1)

The device of claim 1, wherein the image capture apparatus is configured to form a further observation beam for observing the interaction region from a further observation direction and wherein the imaging optic system is configured to generate a further image of the interaction region from the further observation direction.

### Claim 18 (depends on 17)

The device of claim 17, wherein the control apparatus is configured to compare a first intensity value determined on the basis of the further image of the interaction region with a second intensity value determined on the basis of another image of the interaction region captured counter to the advance direction in a plane perpendicular to the beam axis of the high-energy beam.

### Claim 19 (depends on 5)

The device of claim 5, wherein at least one of the observation directions in a plane perpendicular to the beam axis of the high-energy beam does not extend in, or counter to, the advance direction of the cutting process and wherein the control apparatus is configured to determine at least one of a burr formation, a roughness, and a furrow formation as the at least one characteristic variable of the kerf on the basis of the generated image.

### Claim 20 (depends on 1)

The device of claim 1, further comprising an illumination source for illuminating the workpiece in the region to be monitored.

### Claim 21 (depends on 1)

The device of claim 1, wherein the image capture apparatus is configured to record the image through a nozzle opening of a laser processing nozzle for the passage of a laser beam to the workpiece.

### Claim 22 (depends on 1)

The device of claim 1, wherein the image capture apparatus has a detector with a detector surface, at which the image is generated.

### Claim 23 (depends on 1)

The device of claim 1, wherein the image capture apparatus includes a camera, with a detector surface, at which the image is generated.

### Claim 24 (depends on 23)

The device of claim 23, further comprising: at least one of an open-loop and a closed-loop control apparatus for controlling parameters of the cutting process in a manner dependent on the at least one determined characteristic variable.

### Claim 25 (depends on 1)

The device of claim 1, wherein the control apparatus is configured to determine at least one of a cutting front angle of the kerf, an overshoot of a predetermined cutting front angle, and an undershoot of the predetermined cutting front angle of the kerf as the at least one characteristic variable of the kerf on the basis of the captured interaction region, and wherein the device further comprises a closed-loop control apparatus for regulating the cutting front angle to a predetermined constant value by influencing at least one manipulated parameter of the cutting process.

### Claim 26 (depends on 25)

The device of claim 25, in which the closed-loop control apparatus is configured to select the manipulated parameter for regulating the cutting front angle in a manner dependent on a contour to be cut into the workpiece.

### Claim 27 (depends on 25)

The device of claim 25, wherein the closed-loop control apparatus is configured to influence the advance speed between the high-energy beam and the workpiece as a manipulated parameter for regulating the cutting front angle if the advance speed is restricted to a maximum value by the material and the thickness of the workpiece.

### Claim 28 (depends on 27)

The device of claim 27, wherein the closed-loop control apparatus is configured to keep the power of the high-energy beam at a constant value while influencing the advance speed.

### Claim 29 (depends on 25)

The device of claim 25, wherein the closed-loop control apparatus is configured to influence the power of the high-energy beam as a manipulated parameter for regulating the cutting front angle if the advance speed between the high-energy beam and the workpiece is restricted to a maximum value by the geometry of a contour to be cut into the workpiece.

### Claim 30 (depends on 29)

The device of claim 29, wherein the closed-loop control apparatus is configured to keep the advance speed at the maximum value while influencing the power of the high-energy beam.

### Claim 31 (depends on 29)

The device of claim 29, wherein the closed-loop control apparatus is configured to modulate the power of the high-energy beam and influence the modulation of the power of the high-energy beam as a manipulated parameter for regulating the cutting front angle.

### Claim 32 (depends on 25)

The device of claim 25, wherein the control apparatus is configured to determine at least one of an overshoot and an undershoot of the predetermined cutting front angle of the kerf and wherein the closed-loop control apparatus for regulating the cutting front angle has a discontinuous-action controller.

### Claim 33 (depends on 32)

The device of claim 32, wherein the discontinuous-action controller includes at least one of a two-position controller and a three-position controller.

### Claim 34 (depends on 25)

The device of claim 25, wherein the control apparatus is configured to determine the cutting front angle of the kerf and wherein the closed-loop control apparatus for regulating the cutting front angle has a continuous-action controller, in particular a PID controller.

### Claim 35 (depends on 34)

The device of claim 34, wherein the continuous-action controller comprises a PID controller.