JPWO2019220731A1 - Chip diagnostic method and laser processing equipment - Google Patents

Abstract

Provided is a method for diagnosing abnormalities such as wear and spatter adhesion of a chip at the tip of a laser processing head in a laser processing apparatus. A jig (1) that can rotate around the rotation shaft (A) and is provided with a conductor (3) in a part around the rotation shaft (A) is used. The laser processing head (21) is moved so that the emission direction of the laser beam coincides with the rotation axis (A) of the jig (1) and the tip (11) is located in the vicinity of the jig (1). The signal processing unit (13) performs measurement while the jig (1) is rotated. When the variation of the detected capacitance value is larger than the predetermined threshold value, the chip (11) is determined to be abnormal.

Description

The present invention relates to a technique for diagnosing abnormalities such as wear and spatter adhesion of a chip at the tip of a laser processing head in a laser processing apparatus.

When cutting a work piece or the like using a laser processing device, it is important to focus the laser beam on or near the surface of the work piece in order to maintain the processing quality. Therefore, it is necessary to keep the distance between the tip of the laser machining nozzle provided on the robot arm or the like and the workpiece at a desired value, and a capacitance type height sensor is generally used for measuring this distance.

In the capacitive height sensor, the chip at the tip of the laser processing head is used as the sensor electrode. However, as the laser processing is repeated, the chip gradually wears and its shape changes. Further, when the spatter generated during processing adheres to the chip, the shape of the chip changes due to the adhered spatter. The change in chip shape affects the measurement by the capacitive height sensor.

Patent Document 1 discloses a configuration of a capacitance type height sensor of a laser processing machine. In this configuration, by increasing the outer diameter of the upper part of the sensor, it is possible to prevent spatter of the workpiece from adhering to the surface of the insulator layer. Patent Document 2 discloses a configuration of a nozzle and a laser processing head that can prevent spatter and dust from adhering to a capacitive height sensor. Patent Document 3 discloses a configuration of a nozzle that can prevent spatter, dust, and the like from adhering to a capacitance type height sensor and can effectively perform cooling.

Japanese Unexamined Patent Publication No. 10-323784 Japanese Unexamined Patent Publication No. 2014-136218 Japanese Unexamined Patent Publication No. 2014-136233

In order to perform accurate measurement by the capacitance type height sensor, it is desirable that the state of the chip can be easily diagnosed before, for example, laser machining. That is, by diagnosing in advance whether or not there is an abnormality such as wear or spatter adhesion on the chip, the user can replace the chip with a normal chip when there is an abnormality in the chip. As a result, it is possible to prevent construction defects caused by chip abnormalities.

The present invention has been made in view of this point, and an object of the present invention is to provide a method for diagnosing abnormalities such as wear and spatter adhesion of a chip at the tip of a laser processing head in a laser processing apparatus.

In order to achieve the above object, in the present invention, a jig that is rotatable about a rotation axis and has a conductor provided in a part around the rotation axis is used. With the jig rotated, the capacitance is detected by the height sensor, and the presence or absence of an abnormality in the chip is diagnosed based on the magnitude of the variation.

Specifically, in the laser processing apparatus, the method of diagnosing the presence or absence of an abnormality in the chip at the tip of the laser processing head is such that the laser processing apparatus supplies the first voltage signal to the chip and from the chip. It is equipped with a signal processing unit that receives a second voltage signal and measures the distance between the tip of the chip and the work piece from the capacitance value detected from the second voltage signal, and can rotate around the rotation axis. Therefore, using a jig provided with a conductor in a part around the rotation axis, the emission direction of the laser beam coincides with the rotation axis of the jig, and the chip is located in the vicinity of the jig. As described above, the step of moving the laser processing head, the step of measuring by the signal processing unit with the jig rotated, and the variation of the capacitance value detected by the signal processing unit are predetermined. When it is larger than the threshold value, the chip includes a step of determining that the chip is abnormal.

According to this configuration, a jig that can rotate around the rotation axis and has a conductor provided in a part around the rotation axis is used. The signal processing unit moves the laser processing head so that the emission direction of the laser beam coincides with the rotation axis of the jig and the chip is located near the jig, and the jig is rotated. Make a measurement. When the shape of the chip is uniform, the capacitance value detected by the signal processing unit has a small variation. On the other hand, when the shape of the chip is non-uniform due to wear, spatter adhesion, or the like, the capacitance value detected by the signal processing unit becomes large in variation as the jig rotates. Therefore, when the variation of the capacitance value is larger than the predetermined threshold value, it can be determined that the chip is abnormal.

Further, the laser processing apparatus includes a laser processing head, a robot arm to which the laser processing head is attached and moves the laser processing head, a chip attached to the tip of the laser processing head, and a first voltage signal to the chip. A signal processing unit that receives a second voltage signal from the chip and measures the distance between the tip of the chip and the work piece from the capacitance value detected from the second voltage signal, and the above. The chip includes a control unit that controls the operation of the robot arm, and the control unit is rotatable about a rotation axis and uses a jig provided with a conductor in a part around the rotation axis. The signal processing unit includes a chip abnormality determination unit that determines an abnormality of the chip, and the diagnosis control unit has a rotation axis of the jig whose emission direction of laser light is the rotation axis of the jig. The laser processing head is moved to the robot arm so that the chip is located in the vicinity of the jig, and the signal processing unit is instructed to perform measurement in a state where the jig is rotated. Then, the chip abnormality determination unit determines that the chip is abnormal when the variation in the capacitance value detected in the state where the jig is rotated is larger than a predetermined threshold value.

According to this configuration, a jig that can rotate around the rotation axis and has a conductor provided in a part around the rotation axis is used. The diagnostic control unit moves the laser processing head so that the emission direction of the laser beam coincides with the rotation axis of the jig and the chip is located near the jig, and the jig is rotated. , Instruct the signal processing unit to measure. When the shape of the chip is uniform, the capacitance value detected by the signal processing unit has a small variation. On the other hand, when the shape of the chip is non-uniform due to wear, spatter adhesion, or the like, the capacitance value detected by the signal processing unit becomes large in variation as the jig rotates. Therefore, the chip abnormality determination unit can determine that the chip is abnormal when the variation in the capacitance value is larger than the predetermined threshold value.

According to the present invention, it is possible to diagnose abnormalities such as wear and spatter adhesion of a chip at the tip of a laser processing head in a laser processing apparatus.

Configuration of jig used in the embodiment Configuration of Laser Machining Equipment According to the Embodiment Functional configuration of the signal processing unit in the embodiment Flow chart showing the flow of the chip diagnosis method in the embodiment

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the present invention, its applications or its uses.

In the present embodiment, a chip diagnosis method, that is, a method of diagnosing the presence or absence of an abnormality in the chip at the tip of the laser processing head in the laser processing apparatus will be described.

FIG. 1 shows the configuration of a jig used in the chip diagnostic method according to the present embodiment. The jig 1 shown in FIG. 1 includes a tubular member 2 formed of an insulating material and a metal 3 attached to the tubular member 2. The insulating material forming the tubular member 2 is, for example, resin, ceramics, or the like. The metal 3 is, for example, iron or copper, and is attached to a part of the tubular member 2 in the circumferential direction. The jig 1 can be rotated around the rotation axis A by a rotation mechanism including, for example, a motor.

In the present embodiment, when the chip diagnosis method is executed, the laser processing head is set so that the emission direction of the laser beam coincides with the rotation axis A of the jig 1 and the chip 11 is located in the vicinity of the jig 1. Move it. Then, with the jig 1 rotated, measurement is performed by a capacitance type height sensor described later. Here, when the shape of the chip 11 is uniform, the variation in the measured capacitance value is small. On the other hand, if the chip 11 is worn or spatter is attached to the chip 11, the shape of the chip 11 becomes non-uniform, and the measured capacitance value varies widely. Therefore, the presence or absence of abnormality in the chip 11 is diagnosed based on the magnitude of the variation in the measured capacitance value.

FIG. 2 shows the configuration of the laser processing apparatus according to the present embodiment. As shown in FIG. 2, the laser processing apparatus includes a laser processing head 21, a robot arm 23, an optical fiber 24, a laser light source 25, and a control unit 30. For convenience of explanation, illustration and description thereof will be omitted for various parts and the like other than the above-mentioned constituent parts. Further, although not shown, the laser processing apparatus also includes a supply path of the assist gas supplied to the laser processing head 21.

The laser machining head 21 includes a capacitance type height sensor 10 (hereinafter, appropriately simply referred to as a height sensor 10) and a machining nozzle 22, and is attached to the tip of the robot arm 23. The height sensor 10 includes a chip 11, a coaxial cable 12, and a signal processing unit 13, and measures the distance between the tip of the chip 11 and the workpiece. The opening at the tip of the chip 11 corresponds to a laser beam emission port and an assist gas injection port. Further, by arranging the workpiece at a predetermined position, the chip 11 is electrically coupled with a capacitance corresponding to the distance from the workpiece. The coaxial cable 12 electrically connects the chip 11 and the signal processing unit 13. The signal processing unit 13 will be described later.

The laser light source 25 collects the laser light into a power source (not shown), a laser resonator (not shown) that receives power supplied from the power source to generate laser light, and couples the laser light to the optical fiber 24. It has an optical system (not shown) for the purpose.

The optical fiber 24 receives the laser light generated by the laser resonator and focused by the optical system, and is waveguideed to the laser processing head 21. An optical fiber 24 such as a single clad type or a double clad type is appropriately selected depending on the type of laser processing, laser light intensity, and the like. Similarly, the core diameter and the clad diameter of the optical fiber 24 can be changed as appropriate.

A laser machining head 21 is attached to the tip of the robot arm 23, and receives a signal from a control unit 30 based on a machining program or the like to move the laser machining head 21 so as to draw a predetermined trajectory. Further, during laser machining, the position of the laser machining head 21 is controlled so that the distance between the tip of the tip 11 which is the tip of the laser machining head 21 and the workpiece is a predetermined distance.

The control unit 30 includes a robot control unit 31 that controls the operation of the robot arm 23, and a laser control unit 34 that controls the amount of light of the laser light source 25 and the like.

The robot control unit 31 supplies a signal for driving or stopping the joint axis of the robot arm 23 so that the tip of the robot arm 23, that is, the tip of the laser machining head 21 draws a predetermined trajectory based on a machining program or the like. .. Further, the robot control unit 31 has a position control unit 32, and the position control unit 32 uses a laser so that the distance between the tip of the chip 11 and the workpiece is a target value based on the distance measured by the height sensor 10. A signal for controlling the position of the processing head 21, specifically, the position of the robot arm 23 is supplied to the robot arm 23.

The laser control unit 34 controls the power supplied from the power source, the temperature of the laser resonator, and the like so that the laser beam of a desired intensity is emitted.

Further, in the present embodiment, the robot control unit 31 includes a diagnostic control unit 33 that executes an abnormality diagnosis of the chip 11 using the jig 1. The diagnostic control unit 33 controls the operation of the signal processing unit 13 in the robot arm 23 and the height sensor 10 when executing the chip diagnosis method. Further, the diagnostic control unit 33 transmits a signal instructing rotation to a mechanism (not shown) for rotating the jig 1.

FIG. 3 shows the functional block configuration of the signal processing unit 13. The signal processing unit 13 includes a signal generation unit 14, a signal detection unit 15, a distance calculation unit 16, and a chip abnormality determination unit 17.

The signal generation unit 14 generates a voltage signal Vo having a predetermined frequency f and amplitude, and supplies the voltage signal Vo to the chip 11 via the external terminal T and the coaxial cable 12.

The signal detection unit 15 has an external terminal T and detects the voltage signal Vin returned from the chip 11. Further, the signal detection unit 15 has an impedance adjusting resistor connected to the external terminal T. The impedance adjusting resistor may be directly connected to the path between the signal generating unit 14 and the external terminal T.

The distance calculation unit 16 calculates the distance between the tip of the chip 11 and the workpiece based on the voltage signal Vin detected by the signal detection unit 15. In the laser machining apparatus shown in FIG. 2, the position of the laser machining head 21 is controlled based on the difference between the distance calculated by the distance calculation unit 16 and the target value.

When performing an abnormality diagnosis of the chip 11, the chip abnormality determination unit 17 determines whether or not there is an abnormality in the chip 11 from the voltage signal Vin detected by the signal detection unit 15.

ここで、
Ｒはインピーダンス調整用抵抗の抵抗値
Ｃは外部端子Ｔに電気的に結合された静電容量値の総和
ωは電圧信号Ｖｏの角周波数であり、ω＝２πｆである。Here, the voltage signal Vin is a modulation signal in which the voltage signal Vo supplied to the chip 11 is amplitude-modulated by the capacitance or the like electrically coupled to the external terminal T, and the voltage signal amplitude | Vo | The relationship between and the amplitude | Vin | of the modulated signal is expressed by Eq. (1).

here,
R is the resistance value of the impedance adjusting resistor C is the sum of the capacitance values electrically coupled to the external terminal T ω is the angular frequency of the voltage signal Vo, and ω = 2πf.

As is clear from the equation (1), the voltage signal Vo output from the external terminal T is amplitude-modulated by a general low-pass filter determined by the resistance value R, the capacitance value C, and the frequency f of the voltage signal Vo. Received and detected as a modulation signal Vin at the external terminal T.

The capacitance value C is represented by the equation (2) using _{C 0} , C ₁ , and C _{W shown in FIG.}
C = C ₀ + C ₁ + C _W ... (2)
here,
C ₀ is the capacitance value electrically coupled to the external terminal T in the signal processing unit 13. C ₁ is the stray capacitance value of the coaxial cable 12 C _W is the capacitance between the tip of the chip 11 and the workpiece. It is a capacitance value.

The capacitance value C ₀ is a value determined by the arrangement of elements in the signal processing unit 13, the wiring layout, and the like, and is substantially constant. _{Similarly, once} the arrangement of the laser processing head 21 and the coaxial cable 12 is determined, the capacitance value C 1 becomes almost constant. On the other hand, the capacitance value C _W changes according to the distance between the tip of the chip 11 and the workpiece. _{Therefore, the capacitance value C W} can be calculated from the value of the signal Vin, and the distance between the tip of the chip 11 and the workpiece can be calculated from this value.

Further, the chip abnormality determination unit 17 determines whether or not there is a large variation in the _{capacitance value C W} calculated from the value of the signal Vin in the state where the jig 1 is rotating. When there is a large variation, it is determined that the chip 11 has an abnormality.

FIG. 4 is a flowchart showing an example of the chip diagnosis method according to the present embodiment. When the chip diagnosis method is started, first, the diagnosis control unit 33 moves the laser machining head 21 to the position of the jig 1 by supplying a control signal to the robot arm 23 (S11). At this time, the emission direction of the laser beam is aligned with the rotation axis A of the jig 1, and the tip 11 is located in the vicinity of the jig 1.

Then, the diagnostic control unit 33 transmits a signal instructing rotation to the rotation mechanism of the jig 1 to rotate the jig 1. Then, a signal instructing the chip diagnosis is transmitted to the signal processing unit 13. When the signal processing unit 13 receives a signal instructing chip diagnosis from the diagnostic control unit 33, the signal generation unit 14 generates a voltage signal Vo, and the chip abnormality determination unit 17 makes a determination (S12).

The chip abnormality determination unit 17 determines whether or not there is a large variation in the _{capacitance value C W} calculated from the value of the signal Vin in the state where the jig 1 is rotating (S13). This determination is made, for example, by comparing the variation of the _{capacitance value C W with a predetermined threshold value.} When there is a large variation in the capacitance value C _{W , that is, when the variation in the capacitance value C W} is larger than a predetermined threshold value, it is determined that the chip 11 has an abnormality (S14). On the other hand, _{when there is no large variation in the capacitance value C W} , it is determined that there is no abnormality in the chip 11 (S15). The chip abnormality determination unit 17 transmits a signal indicating an abnormality determination result to the diagnosis control unit 33.

When the diagnosis control unit 33 receives the signal indicating the abnormality determination result transmitted from the chip abnormality determination unit 17, the diagnosis control unit 33 notifies the user of the abnormality determination result (S16). For example, the abnormality determination result is displayed on a monitor arranged in the laser processing apparatus. When it is determined that the chip 11 has an abnormality, the user replaces the chip 11 with a normal chip.

As described above, according to the present embodiment, in the abnormality diagnosis of the chip 11, a jig 1 that is rotatable about the rotation axis A and has a conductor 3 provided in a part around the rotation axis A is used. A state in which the laser processing head 21 is moved and the jig 1 is rotated so that the emission direction of the laser beam coincides with the rotation axis A of the jig 1 and the chip 11 is located in the vicinity of the jig 1. Then, the signal processing unit 13 performs the measurement. When the shape of the chip is uniform, the capacitance value detected by the signal processing unit 13 has a small variation. On the other hand, when the shape of the chip is non-uniform due to wear, spatter adhesion, or the like, the capacitance value detected by the signal processing unit 13 becomes large in variation as the jig rotates. Therefore, when the variation of the capacitance value is larger than the predetermined threshold value, it can be determined that the chip is abnormal.

The configuration of the jig 1 is not limited to that shown in the embodiment. For example, instead of the metal 3, another type of conductor may be attached to the tubular member 2. Alternatively, instead of using the tubular member 2, a disk-shaped member may be used and a metal piece may be erected on a part of the peripheral edge thereof.

Further, the signal processing unit 13 of the height sensor 10 may be incorporated in the control unit 30 of the laser processing device.

According to the present invention, it is possible to diagnose abnormalities such as wear and spatter adhesion on the chip at the tip of the laser processing head in the laser processing apparatus, which is useful in preventing construction defects.

1 Jig 3 Conductor 11 Chip 13 Signal processing unit 17 Chip abnormality determination unit 21 Laser machining head 23 Robot arm 30 Control unit 33 Diagnostic control unit

Claims (2)

A method of diagnosing the presence or absence of an abnormality in the chip at the tip of the laser processing head in a laser processing apparatus.
The laser processing apparatus supplies the first voltage signal to the chip, receives the second voltage signal from the chip, and receives the second voltage signal from the chip, and from the capacitance value detected from the second voltage signal, the tip of the chip and the machine to be processed Equipped with a signal processing unit that measures the distance to an object,
Using a jig that can rotate around the axis of rotation and has a conductor provided in a part around the axis of rotation.
A step of moving the laser processing head so that the emission direction of the laser beam coincides with the rotation axis of the jig and the chip is located in the vicinity of the jig.
A step in which the signal processing unit performs measurement while the jig is rotated, and
A chip diagnostic method comprising a step of determining that the chip is abnormal when the variation of the capacitance value detected by the signal processing unit is larger than a predetermined threshold value. Laser machining head and
A robot arm to which the laser machining head is attached and moves the laser machining head,
The tip attached to the tip of the laser processing head and
While supplying the first voltage signal to the chip, the second voltage signal from the chip is received, and the distance between the tip of the chip and the workpiece is measured from the capacitance value detected from the second voltage signal. Signal processing unit and
A control unit that controls the operation of the robot arm is provided.
The control unit includes a diagnostic control unit that can rotate around a rotation axis and executes an abnormality diagnosis of the chip using a jig provided with a conductor in a part around the rotation axis.
The signal processing unit includes a chip abnormality determination unit that determines an abnormality of the chip.
The diagnostic control unit
The laser processing head is moved to the robot arm so that the emission direction of the laser beam coincides with the rotation axis of the jig and the chip is located in the vicinity of the jig.
In the state where the jig is rotated, the signal processing unit is instructed to perform measurement.
The chip abnormality determination unit
A laser processing apparatus characterized in that when the variation in the capacitance value detected in a state where the jig is rotated is larger than a predetermined threshold value, the chip is determined to be abnormal.

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