JP5631138B2 - Laser cutting method and apparatus - Google Patents

Description

  The present invention relates to a laser cutting method and apparatus for laser cutting a plate-like workpiece. More specifically, the present invention detects an appropriate focal position with respect to the workpiece by piercing the workpiece. The present invention relates to a laser cutting method and apparatus for performing laser cutting of a workpiece with a detected focal position.

  2. Description of the Related Art Conventionally, in a laser processing machine that performs laser cutting processing of a plate-shaped workpiece, a CNC device that controls the laser processing machine is provided with a condition file in which processing conditions for each workpiece are registered in advance. When cutting the workpiece, a condition file corresponding to the workpiece set in the laser beam machine is called, and the workpiece is laser-cut according to the machining conditions registered in the condition file.

  By the way, in order to perform stable processing in laser cutting processing, the focal position of the laser beam with respect to the surface of the workpiece is an important condition. Therefore, even when the position of the condenser lens is adjusted so that the focal position is adjusted to the position of the processing condition registered in the condition file, the deterioration state of the condenser lens used or the individual lenses used Since there is no function for correcting disturbances such as differences in focal length due to differences in laser oscillators over time, stable processing may not be possible due to the disturbances. In this case, it is necessary to detect and re-register the focal position of the condenser lens.

  That is, when laser cutting is performed, the focal position of the condensing lens is an important element, and thus the focal position of the condensing lens is detected (for example, see Patent Documents 1 and 2).

JP-A-7-132391 JP 2005-334928 A

  In the invention described in Patent Document 1, when the focal position of the condenser lens with respect to the surface of the workpiece is adjusted up and down, the focal position matches the surface of the workpiece, and the detected processing light intensity becomes maximum. In addition, there is a configuration in which it is detected that the focal position coincides with the workpiece surface.

  In the invention described in Patent Document 2, when the focal position coincides with the surface of the workpiece, a high-luminance blue plasma is generated. When the generation of this plasma is detected, the focal position is the surface of the workpiece. Is detected as a match.

  That is, conventionally, the position of the condenser lens when the focal position coincides with the surface of the workpiece is detected, and various laser processings are performed by adjusting the focal position with respect to the workpiece based on the detected position. That is, conventionally, a process for detecting the focal position is necessary before laser cutting the workpiece, and a process for adjusting the focal position is necessary after detecting the focal position, which is problematic in improving work efficiency. .

The present invention has been made in view of the conventional problems as described above, and is a laser cutting processing method. Prior to performing laser cutting processing of a plate-shaped workpiece, various approach positions of the condensing lens with respect to the workpiece are various. The piercing process is performed multiple times with various changes in the focal position of the workpiece, and the detected value of the amount of scattered light detected at the time from the start of the piercing process until the hole penetrates is minimized. The workpiece is laser cut while holding the focal position at the value.

  Further, the laser cutting method is a plurality of piercing processes in which the focal position with respect to the workpiece is changed variously by variously changing the approach position of the condensing lens with respect to the workpiece prior to laser cutting of the plate-like workpiece. And performing laser cutting of the workpiece while maintaining the focal position when the machining time detected during the plurality of times of piercing is minimized.

Further, a laser processing head provided with a condensing lens for condensing laser light oscillated from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to the work, and piercing of the work Photo / electric conversion means for detecting the amount of scattered light in the time from the start of piercing processing to the time when the hole penetrates and converting it to a voltage, and the detected light voltage converted by the light / electric conversion means and the focal position The first memory for storing the focal position adjusted by the adjusting means in association with the detected photovoltage and the focal position detected at the time from the start of the piercing process until the hole penetrates at the next piercing process The second memory to be stored and the detected light voltage of the first memory and the detected light voltage of the second memory are compared to select a smaller value, and the first memory is updated. A comparison unit, and is characterized in that it comprises a, and the focal point position adjusting means for adjusting the focal position in the associated focal position detection light voltage selected by the comparison means.

  Further, a laser processing head provided with a condensing lens for condensing laser light oscillated from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to the work, and piercing of the work A first memory for storing a penetrating time detecting means for detecting a penetrating time at the time of processing; a penetrating time detected by the penetrating time detecting means; and a focal position adjusted by the focal position adjusting means; The second memory for storing the penetrating time and the focal position detected during the piercing process in association with each other, the penetrating time of the first memory and the penetrating time of the second memory are compared, and a smaller value is selected. Comparing means for updating the memory, and the focal position adjusting means for adjusting the focal position to a focal position related to the penetration time selected by the comparing means. It is characterized in.

Further, a laser processing head provided with a condensing lens for condensing laser light oscillated from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to a work, and the laser processing Including a focal position at a machining condition selected from a machining condition file in a control device for controlling the movement of the head, and adjusting the focal position in the + direction and the − direction with respect to this focal position, At the time of piercing processing, the light / electricity conversion means that detects the amount of scattered light in the time from the start of piercing processing until it penetrates the hole and converts it into voltage each time , and multiple detections converted by this light / electricity conversion means A memory storing the light voltage and the focal position adjusted by the focal position adjusting means in association with each other and the detected light voltage of the memory a plurality of times are compared with each other. Comparing means for selecting a value, and the focal position adjusting means for adjusting the focal position to a focal position related to the minimum detected light voltage selected by the comparing means. is there.

  Further, a laser processing head provided with a condensing lens for condensing laser light oscillated from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to a work, and the laser processing Including a focal position at a machining condition selected from a machining condition file in a control device for controlling the movement of the head, and adjusting the focal position in the + direction and the − direction with respect to this focal position, A penetrating time detecting means for detecting the penetrating time at the time of piercing processing each time, and a memory for storing a plurality of penetrating times detected by the penetrating time detecting means and the focal position adjusted by the focal position adjusting means in association with each other And a comparing means for selecting the minimum value by comparing the penetration time of the memory, and the penetration time of the minimum value selected by the comparison means. And it is characterized in that it comprises said focal position adjusting means for adjusting the focal position communicating the focal position.

  According to the present invention, an appropriate focal position at the time of piercing processing is obtained by performing piercing in advance, and laser cutting processing is performed under the conditions of the obtained focal position. Even in such a case, an appropriate focal position can be obtained immediately, and laser cutting of the workpiece can be efficiently started while maintaining good cutting plane accuracy.

It is explanatory drawing which showed notionally and schematically the whole structure of the laser cutting processing apparatus which concerns on embodiment of this invention. It is explanatory drawing of a piercing process. It is explanatory drawing which shows the relationship between the focus position at the time of a piercing process, and a detection photovoltage.

  Referring to FIG. 1, as conceptually and schematically, a laser cutting machine 1 that performs laser cutting of a plate-like workpiece W is similar to a general laser processing machine in the X, Y, Z A laser processing head 3 is provided that can be moved and positioned in the axial direction. As is well known, a condensing lens 5 is provided in the laser processing head 3, and a bend mirror 9 for reflecting the laser beam LB oscillated from the laser oscillator 7 in the direction of the condensing lens 5. Is provided.

  Further, in order to adjust the focal position with respect to the workpiece W, the laser processing head 3 adjusts the position of the condensing lens 5 in a direction approaching and moving away from the workpiece W (vertical direction in FIG. 1). A servo motor 11 is provided. Further, the laser processing head 3 is provided with an appropriate number of optical sensors 13 for detecting scattered light (visible light) from the laser processing position of the workpiece W. The scattered light is visible light that is emitted when the workpiece W is irradiated with the laser light LB and the metal melts, and is not reflected light of the laser light LB from the processing position.

  The control device 15 for controlling the laser cutting processing device 1 is a CNC control device or the like, and includes a CPU 17, input means 19, ROM 21, RAM 23, and display means 25. Further, the control device 15 is provided with a processing condition file 27 in which processing conditions for performing laser cutting processing of the workpiece W are registered in advance corresponding to the materials and plate thicknesses of the various workpieces W. The processing conditions registered in the processing condition file 27 include, for example, a cutting focal position with respect to the workpiece surface, a cutting speed, a laser output, a pulse laser frequency, a duty ratio, a gas type used, a gas pressure, and a laser processing head. For example, the cutting gap between the nozzle and the workpiece surface. Then, the laser oscillator 7 and the servo motor 7 are controlled based on the processing conditions stored in advance in the processing condition file 27, and the laser cutting processing of the workpiece W is performed.

  Further, the control device 15 is a light / voltage converting means for converting the amount of light detected by the optical sensor 13 for detecting scattered light at the laser processing position into a voltage (detected light voltage) during laser processing of the workpiece W. 29 and a focus position adjusting means 31 for controlling the servo motor 11 to adjust the focus position of the condenser lens 5 with respect to the surface of the workpiece W.

  Further, when the workpiece W is subjected to piercing processing, the control device 15 detects the amount of scattered light detected by the optical sensor 13 (this amount of light is from the start of piercing processing until the hole penetrates. (A light amount detected in a very short time) is stored in association with the value of the detected light voltage converted into a voltage by the light / electric converter 29, that is, the detected value of the scattered light amount and the focal position at the time of piercing. A first memory 33 is provided. In addition, a second memory 35 is provided that stores the focal position and the detected value of the detected light voltage in association with each other when the focal position is changed and piercing is performed.

  Further, the control device 15 is provided with a comparison means 37 for comparing the detected values of the detected light voltage stored in the first and second memories 33 and 35. The comparison means 37 compares the detected light voltages of the first and second memories 33 and 35 to select a small value, and updates the contents of the first memory 33 to the selected small value and the work W The function of updating the focal position parameter in the machining program stored in advance in the RAM 23 to the focal position stored in the first memory 33 in order to perform the laser cutting process. Therefore, the first memory 33 stores the minimum detected light voltage value detected when the workpiece W is pierced and the focal position at that time in association with each other.

  Further, the control device 15 performs laser cutting of the workpiece W according to the machining program stored in the RAM 23 in a state where the focal position of the condenser lens 5 is adjusted to the focal position stored in the first memory 33. In order to perform processing, an axis operation control means 39 for controlling movement of the laser processing head 3 in the X, Y, and Z axis directions is provided.

  In the configuration as described above, in order to perform laser cutting of the workpiece W, piercing is performed a plurality of times in order to adjust the focal position of the condenser lens 5 with respect to the surface of the workpiece W to an appropriate position. . In this case, the piercing process is performed on a part to be an end material of the workpiece W. Then, when performing the piercing process, a corresponding processing condition is selected from the processing condition file 27 corresponding to the material and thickness of the workpiece W. There is no problem if the focal position in the selected processing condition is correct, but the focal position may be slightly changed due to, for example, deterioration of the condenser lens 5.

  Therefore, as shown in (A), (B), (C), (D), and (E) of FIG. 2, parameters B1, The focal position is changed to the upper surface side (A + B1, A + B2) and the lower surface side (A-B1, A-B2) of the workpiece W by B2, and piercing is performed a plurality of times, for example, A + B2, A + B1, A, A-B1. , A-B2. When the piercing process is sequentially performed as described above, the light amount of the scattered light detected by the optical sensor 13 is converted into a voltage by the photoelectric conversion means 29. Then, comparison of the sequentially detected voltages (detected light voltages) by the comparison unit 37 is repeated, the minimum detected light voltage is stored in the first memory 33, and the contents of the first memory 33 are updated.

  Further, the focal position parameter in the machining program stored in the RAM 23 for performing laser cutting according to the machining conditions selected from the machining condition file 27 corresponding to the workpiece W to be machined, input from the input means 19, The focus position stored in the first memory 33 and updated is updated.

  That is, as described above, when the detected light voltage when the piercing process is sequentially performed a plurality of times, as shown in FIG. 3, the minimum value is the focal position of A-B1, it is registered in the processing condition file 27. The focus position A is updated to the focus position A-B1 in the processing program for performing laser cutting, and the workpiece W is subjected to laser cutting while holding the focus position at the focus position A-B1. It is.

  By the way, when the workpiece W is pierced, the minimum value of the detected light voltage is that the amount of scattered light received by the optical sensor 13 is small. In other words, the piercing time is the shortest. The shortest piercing time means that the focal position with respect to the surface of the workpiece W is adjusted to an optimum position. Therefore, high-precision laser processing can be performed by performing laser cutting processing by adjusting the focal position to the focal position when the piercing processing time is minimum.

  As already understood, prior to performing laser cutting processing of the workpiece W, the focal position with respect to the workpiece W is changed by variously changing the approach position of the condenser lens 5 with respect to the workpiece W, and a plurality of piercing processes are performed. Since the workpiece W is subjected to laser cutting processing by adjusting the focal position to the focal position when the detected value of the scattered light amount detected at the time becomes the minimum value, the focal position is caused by deterioration of the condenser lens 5 or the like. Even in the case of changing, the laser cutting process is performed with the focal position adjusted to an appropriate position with respect to the surface of the workpiece W during the laser cutting process. Therefore, laser cutting can always be performed with high accuracy.

  By the way, in the above description, the piercing process is started on the workpiece W, the amount of scattered light until the hole penetrates is detected, and the focal position with the minimum detected value is obtained. However, minimizing the amount of scattered light is equivalent to minimizing the piercing processing time, so the time from the start of piercing processing to the time of hole penetration is detected, and the processing time detected during multiple piercing operations is minimized. It is also possible to store the current focal position in the first memory 33 and update the focal position parameter in the machining program to the focal position stored in the first memory 33.

  In this case, the control device 15 includes a penetrating time detection means 41. Then, when piercing processing is started by irradiating the workpiece W with the laser beam LB, the metal on the workpiece surface melts and emits scattered light, so that the penetrating time (from when the scattered light is detected by the optical sensor 13 ( Start timing of piercing time. When the hole is penetrated through the workpiece W, the portion of the workpiece W where the metal is melted is drastically reduced and the amount of scattered light is drastically reduced. Can be detected.

  Therefore, as described above, the detected piercing processing time and the focal position at that time are associated and stored in the first memory 33, and the piercing processing time at the next piercing processing and the focal position at that time are associated with each other in the second memory. 35. As described above, the minimum piercing time can be obtained by sequentially repeating the comparison of the piercing times stored in the first and second memories 33 and 35 by the comparison means 37. Therefore, by adjusting the focal position of the condenser lens 5 to the focal position corresponding to the obtained minimum piercing processing time and performing laser cutting processing, the same effects as described above can be obtained.

  The present invention is not limited to the embodiment as described above, and can be implemented in other forms by making appropriate changes. That is, in the above description, the detected photovoltage or the piercing time is detected each time the focal position is sequentially changed to A + B2, A + B1, A, A-B1, A-B2 and a plurality of times of piercing is sequentially performed. The previous detection value and the current detection value are compared, and when the current detection value is small, the data is stored in the memory repeatedly. When the current detection value becomes larger than the previous detection value, the previous detection value is assumed to be the minimum value.

  However, including the focal position A in the processing conditions, the focal position is adjusted in the + direction and the − direction (vertical direction) around the focal position A (A + B1, A + B2: A−B1, A−B2), A value (detected value) detected each time the amount of scattered light at the time of multiple times of piercing processing is associated with the focal position at that time, and stored in the first memory 33 each time, for example. Then, all the detection values stored in the memory 33 are compared by the comparison means 37, and the minimum detection value is selected. And it can also be set as the structure which adjusts a focus position to the position corresponding to this selected minimum detection value, and performs a laser cutting process.

DESCRIPTION OF SYMBOLS 1 Laser cutting processing apparatus 3 Laser processing head 5 Condensing lens 7 Laser oscillator 13 Optical sensor 15 Control apparatus 27 Processing condition file 29 Photoelectric conversion means 31 Focus position adjustment means 33 1st memory 35 2nd memory 37 Comparison means 39 Axis Operation control means 41 Penetration time detection means

Claims (6)

Prior to laser cutting of a plate-shaped workpiece, the laser cutting method is used for multiple times of piercing processing in which the focusing position with respect to the workpiece is variously changed by variously changing the approach position of the condenser lens with respect to the workpiece. , Laser cutting of the workpiece while holding the focal position when the detected value of the amount of scattered light detected in the time from the start of the piercing process to the time when the hole penetrates during the multiple piercing processes A laser cutting method characterized by the above.   Prior to laser cutting of a plate-shaped workpiece, the laser cutting method is used for multiple times of piercing processing in which the focusing position with respect to the workpiece is variously changed by variously changing the approach position of the condenser lens with respect to the workpiece. A laser cutting method characterized in that a laser cutting process is performed on a workpiece while maintaining a focal position when the processing time detected during the plurality of times of piercing is minimum. A laser processing head having a condensing lens for condensing laser light emitted from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to the workpiece, and piercing of the workpiece; The light / electric conversion means for detecting the amount of light scattered during the time from the start of piercing until the hole penetrates and converting it to a voltage, the detected light voltage converted by the light / electric conversion means and the focal position adjusting means A first memory for storing the focal position adjusted by the correlation in association with the detected photovoltage and the focal position detected at the time from the start of the piercing process until the hole penetrates in the next piercing process. Comparing the detected light voltage of the second memory with the detected light voltage of the first memory and the detected light voltage of the second memory, selecting a smaller value, and updating the first memory Stage and laser cutting apparatus characterized by comprising a said focal position adjusting means for adjusting the focal position in the associated focal position detection light voltage selected by the comparison means.   A laser processing head having a condensing lens for condensing laser light emitted from a laser oscillator, a focal position adjusting means for adjusting a focal position of the condensing lens with respect to the workpiece, and piercing of the workpiece; A penetrating time detecting means for detecting the penetrating time of the first time, a first memory for storing the penetrating time detected by the penetrating time detecting means in association with the focal position adjusted by the focal position adjusting means, and the next piercing The second memory for storing the penetrating time detected at the time of processing and the focal position in association with each other, the penetrating time of the first memory and the penetrating time of the second memory are compared, and a small value is selected. Comparing means for updating, and the focal position adjusting means for adjusting the focal position to a focal position related to the penetration time selected by the comparing means. Laser cutting device according to claim. A laser processing head including a condensing lens for condensing laser light oscillated from a laser oscillator; a focal position adjusting unit that adjusts a focal position of the condensing lens with respect to a work; and Multiple times of piercing for a workpiece including a focal position at a machining condition selected from a machining condition file in a control device for controlling movement, and adjusting the focal position in the + direction and the-direction with respect to the focal position Light / electric conversion means that detects the amount of scattered light in the time from the start of piercing processing to the time when the hole penetrates and converts it into a voltage each time , and a plurality of detection light voltages converted by this light / electricity conversion means And a memory for associating and storing the focal position adjusted by the focal position adjusting means, and comparing a plurality of detection photovoltages of the memory with a minimum value. A laser cutting processing apparatus comprising: a comparing means for selecting; and the focus position adjusting means for adjusting a focus position to a focus position related to a minimum detected light voltage selected by the comparing means. .   A laser processing head including a condensing lens for condensing laser light oscillated from a laser oscillator; a focal position adjusting unit that adjusts a focal position of the condensing lens with respect to a work; and Multiple times of piercing for a workpiece including a focal position at a machining condition selected from a machining condition file in a control device for controlling movement, and adjusting the focal position in the + direction and the-direction with respect to the focal position A penetrating time detecting means for detecting the penetrating time of each time, a memory for associating and storing a plurality of penetrating times detected by the penetrating time detecting means and the focal position adjusted by the focal position adjusting means, Comparing means for comparing the penetration time of the memory to select a minimum value, and a relation of the minimum penetration time selected by the comparison means. Laser cutting apparatus characterized by comprising said focal position adjusting means for adjusting the focal position at the focal position.

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