WO2021002188A1 - Laser processing head, laser processing device and laser processing control method - Google Patents

Abstract

A laser processing head according to the present invention is provided with: a first mirror and a second mirror that split a portion of reflected light reflected from a workpiece, said portion being collimated by a first condenser lens, into return light, second mirror transmitted light, and second mirror reflected light; a first shielding member in which a first opening is formed, wherein the first opening allows, of the second mirror transmitted light, light having a reflection angle at the workpiece within a first range to pass therethrough as first passage light; a second shielding member in which a second opening is formed, wherein the second opening allows, of the second mirror reflected light, light having a reflection angle at the workpiece within a second range, which is different from the first range, to pass therethrough as second passage light; a first optical sensor that detects the light quantity of the first passage light; and a second optical sensor that detects the light quantity of the second passage light.

Description

Laser machining head, laser machining equipment and laser machining control method

The present disclosure relates to a laser processing head that emits laser light emitted by a laser oscillator and passed through an optical fiber toward a work, a laser processing apparatus provided with the laser processing head, and a laser processing control method by the laser processing apparatus. ..

Patent Document 1 describes a collimating lens that parallelizes the laser light emitted from the exit end face of the optical fiber, and a condensing lens that collects the laser light parallelized by the collimating lens and emits it toward the work. A bend mirror that reflects a part of the reflected light reflected from the work and parallelized by the condensing lens toward the collimating lens as return light and transmits the rest of the reflected light. A laser processing head including an optical sensor that detects the amount of reflected light transmitted through a bend mirror is disclosed.

Japanese Unexamined Patent Publication No. 2012-17962

By the way, in a laser processing apparatus provided with a laser processing head as in Patent Document 1, in general, at least a part of the reflected light from the work passes through a collimating lens as return light and passes through a core or a cladding of an optical fiber. In contrast, the light enters a plurality of places of the laser processing apparatus such as the inside of the oscillator, the connection portion of the optical fiber, and the protective layer arranged on the outer periphery of the clad of the optical fiber. Then, a problem such as damage occurs at a place where the incident light amount of the return light exceeds a predetermined allowable value. In a normal laser processing apparatus, the permissible values of the amount of incident light at a plurality of locations where the return light is incident often differ. Therefore, there is a desire to individually acquire the incident light amount of the return light at a plurality of locations of the laser processing apparatus and to predict or warn the degree of danger by comparing with the permissible value of each location. However, in Patent Document 1, since only one optical sensor is provided for detecting the amount of reflected light from the work, it is not possible to individually acquire the amount of incident light of the return light at a plurality of locations of the laser processing apparatus.

The present disclosure has been made in view of such a point, and the purpose of the present disclosure is to individually acquire the incident light amount of the return light at a plurality of locations of the laser processing apparatus and set the allowable value of the incident light amount at each location. The purpose is to be able to predict or warn the degree of danger accordingly.

In order to achieve the above object, the present disclosure is a laser processing head that emits laser light emitted from a laser oscillator and passed through an optical fiber toward a work, and the laser light emitted from the optical fiber is emitted. A collimating lens to be parallelized, a condensing lens that condenses the laser light parallelized by the collimating lens and emits it toward the work, and a condensing lens that reflects from the work and is parallelized by the condensing lens. An optical system that divides the reflected light into a plurality of divided lights including a return light returning to the collimating lens, a first divided light, and a second divided light, and the first divided light, the reflected angle of the work is the first. A first window portion is formed through which light within the range of 1 is passed as the first passing light, and among the first divided lights, the first one that shields the light whose reflection angle in the work is outside the first range. A shielding member and a second window portion for passing light having a reflection angle in the work within a second range different from the first range among the second divided lights as the second passing light are formed. Of the second divided light, the second shielding member that shields the light whose reflection angle in the work is outside the second range, the first optical sensor that detects the amount of the first passing light, and the first. 2 It is characterized by including a second optical sensor that detects the amount of passing light.

As a result, the amount of light detected by the first optical sensor becomes a value corresponding to the amount of return light whose reflection angle in the work is within the first range, and the amount of light detected by the second optical sensor is the amount of light detected by the work. The reflection angle in is a value corresponding to the amount of return light within the second range. Then, the return light whose reflection angle on the work is within the first range and the return light whose reflection angle on the work is within the second range are oppositely incident on different parts of the laser processing apparatus. The amount of light detected by the first and second optical sensors is a value corresponding to the amount of incident light of the return light at different points of the laser processing apparatus. Therefore, it is possible to individually measure the incident light amount of the return light at a plurality of locations of the laser processing apparatus and predict or warn the degree of danger according to the permissible value of the incident light amount at each location.

It is possible to individually acquire the incident light amount of the return light at a plurality of locations of the laser processing device and predict or warn the degree of danger according to the permissible value of the incident light amount at each location.

It is the schematic which shows the structure of the laser processing apparatus which concerns on Embodiment 1 of this disclosure. It is the schematic which shows the structure of the laser processing head. (A) is a plan view of the first shielding member, and (b) is a cross-sectional view taken along the line IIIb-IIIb of FIG. 3 (a). (A) is a plan view of the second shielding member, and (b) is a cross-sectional view taken along the line IVb-IVb of FIG. 4 (a). It is a graph which illustrates the amount of light detected by the 1st optical sensor. It is a graph which illustrates the amount of light detected by the 2nd optical sensor. It is sectional drawing which shows the outline of the exit end portion of an optical fiber 90. FIG. 2 is a view corresponding to FIG. 2 of the second embodiment. (A) is a diagram corresponding to FIG. 4 (a) of the second embodiment, and (b) is a diagram corresponding to FIG. 4 (b) of the second embodiment. (A) is a plan view of the third shielding member, and (b) is a cross-sectional view taken along the line IXb-IXb of FIG. 9 (a). (A) is a diagram corresponding to FIG. 3 (a) of the third embodiment, and (b) is a diagram corresponding to FIG. 3 (b) of the third embodiment. (A) is a diagram corresponding to FIG. 4 (a) of the third embodiment, and (b) is a diagram corresponding to FIG. 4 (b) of the third embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

(Embodiment 1)
Hereinafter, embodiments of the present disclosure 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 disclosure, its application or its use.

Also, in the following explanation, "matching" includes not only those that exactly match, but also those that include manufacturing tolerances and processing tolerances. The term "approximately parallel" includes not only those that are strictly parallel but also those that are almost parallel within a certain predetermined error range.

(Embodiment 1)
FIG. 1 shows the configuration of the laser processing apparatus 100 according to the first embodiment. The laser processing apparatus 100 includes a laser processing head 30, a manipulator 60, a controller 70, a laser oscillator 80, and an optical fiber 90. There is.

The laser processing head 30 irradiates the work W with the laser light LB from the optical fiber 90. A laser machining head 30 is attached to the tip of the manipulator 60 to move the laser machining head 30. The controller 70 controls the operation of the laser processing head 30, the operation of the manipulator 60, and the laser oscillation of the laser oscillator 80. The laser oscillator 80 emits the laser beam LB to the optical fiber 90 by oscillation. The optical fiber 90 guides the laser beam LB emitted by the laser oscillator 80 to the laser processing head 30. With such a configuration, the laser processing apparatus 100 causes the laser processing head 30 and the manipulator 60 to operate the laser processing head 30 and the manipulator 60 to irradiate the work W with the laser light LB emitted from the laser oscillator 80 in a desired trajectory.

The laser processing device 100 is used for cutting the work W, welding, and the like.

As shown in FIG. 2, the laser processing head 30 is emitted by a collimating lens 31 and a collimating lens 31 that parallelize the emitting beam OB (laser light) emitted from the emitting end surface of the optical fiber 90 and emit it as a collimating beam CB. The collimated beam CB (laser light) is focused so as to be focused at the processing point in the work W and emitted toward the work W as the processing beam PB, and the reflected light from the work W is parallelized. The condenser lens 32 of 1 and the protective glass 33 interposed between the first condenser lens 32 and the work W are provided. In FIG. 2, θ0 indicates the emission angle of the emission beam OB actually emitted from the optical fiber 90.

A state in which the first mirror 34 is tilted between the collimating lens 31 and the first condensing lens 32 at a predetermined tilt angle with respect to the optical axis OA1 of the collimating lens 31 and the first condensing lens 32. It is arranged by. The predetermined tilt angle can be set arbitrarily, but it is desirable to set it to approximately 45 degrees. The first mirror 34 transmits most of the collimated beam CB emitted by the collimating lens 31 toward the first condensing lens 32. It is desirable that the first mirror 34 is configured to transmit 99.0% or more of the collimated beam CB. Further, the first mirror 34 reflects a part of the reflected light reflected from the work W and passed through the first condensing lens 32 as the first mirror reflected light RB1 and passes the rest of the reflected light. It returns to the collimating lens 31 and is emitted as light FB. As the first mirror 34, a quartz glass mirror in which antireflection film coating for preventing reflection of the collimated beam CB is similarly applied to both surfaces thereof can be used. It is desirable to set the reflectance of the antireflection film as low as possible, and specifically, it is desirable to set it to 1.0% or less. In FIG. 1, the work W is arranged near the focal point of the first condensing lens 32 so that the power density of the laser beam incident on the work W is high. Therefore, the return light FB reflected from the work W and passing through the first condenser lens 32 becomes substantially parallel light. However, the work W is arranged at a position away from the focal point of the first condensing lens 32, and only a part of the return light FB reflected from the work W and passing through the first condensing lens 32 is approximately parallel light. It may be set to.

A second mirror 35 is arranged in parallel with the first mirror 34 at a position separated from the first mirror 34 in the emission direction of the first mirror reflected light RB1. The second mirror 35 transmits a part of the first mirror reflected light RB1 as the second mirror transmitted light TB2, and reflects the rest of the first mirror reflected light RB1 as the second mirror reflected light RB2. Therefore, the reflected light reflected from the work W by the first mirror 34 and the second mirror 35 and parallelized by the first condensing lens 32 is the return light FB and the second mirror as the first divided light. An optical system that divides the transmitted light TB2 and the second mirror reflected light RB2 as the second divided light is configured. The reflectance of the first mirror reflected light RB1 in the second mirror 35 is not particularly limited, but may be set to 50% so that the second mirror transmitted light TB2 and the second mirror reflected light RB2 are substantially equal. desirable.

At a location distant from the second mirror 35 in the emission direction of the second mirror transmitted light TB2, the square plate-shaped first shielding member 36 also shown in FIG. 3 is perpendicular to the optical axis of the second mirror transmitted light TB2. It is arranged. The first shielding member 36 is made of an aluminum alloy, a metal such as copper, iron, or stainless steel, or a resin having a property of not transmitting the second mirror transmitted light TB2. A first opening 36a as a circular first window portion is formed through the center of the first shielding member 36. The center of the first opening 36a coincides with the optical axis OA2 of the second mirror transmitted light TB2. The diameter D1 of the first opening 36a is set so that, of the second mirror transmitted light TB2, the light whose reflection angle at the work W is within the first range is passed as the first passing light PB1. Further, due to the non-formed region of the first opening 36a in the first shielding member 36, the reflection angle of the second mirror transmitted light TB2 of the second mirror transmitted light TB2 is out of the first range. Some light) is shielded. That is, the first shielding member 36 has a first window portion (first opening 36a) in a circular region having a diameter D1 and shields light incident on the outside of the circular region. Specifically, the first range is a range corresponding to a predetermined first set angle SA1 or less at 0 degrees or more. The first set angle SA1 is the return light FB, when the light whose reflection angle at the work W is the first set angle SA1 returns to the emission end of the optical fiber 90, the light has an incident angle equal to the maximum light receiving angle θ1. It is set to enter the fiber 90. The maximum light receiving angle θ1 is the maximum value of the incident angle of light that can propagate in the opposite direction (toward the laser oscillator 80) through the core 91 (see FIG. 6) of the optical fiber 90. That is, this θ1 corresponds to the NA (Numerical Aperture) of the optical fiber 90. Therefore, the diameter D1 of the first opening 36a corresponds to the maximum diameter of the incident beam that can propagate through the core 91 (see FIG. 6) of the optical fiber 90 in the opposite direction (laser oscillator 80 side) as a whole. Further, in FIG. 3, D0 corresponds to the diameter of the incident beam of the return light FB when the return light FB returns by the path opposite to the emission beam OB actually emitted from the optical fiber 90.

A second condensing lens 37 is arranged in parallel with the first shielding member 36 at a position separated from the first shielding member 36 in the emission direction of the second mirror transmitted light TB2. The optical axis of the second condenser lens 37 coincides with the center of the first opening 36a (the optical axis OA2 of the second mirror transmitted light TB2).

A first optical sensor 38 is arranged at a position away from the second condensing lens 37 in the emission direction of the second mirror transmitted light TB2 with its light receiving surface facing the second condensing lens 37. Has been done. The light receiving surface of the first optical sensor 38 is preferably located at the focal point of the second condenser lens 37, but this is not the case. The amount of light detected by the first optical sensor 38 is the amount of light of the first passing light PB1.

Further, at a location separated from the second mirror 35 in the emission direction of the second mirror reflected light RB2, the square plate-shaped second shielding member 39 also shown in FIG. 4 is perpendicular to the optical axis of the second mirror reflected light RB2. It is arranged in a state. The second shielding member 39 is also made of a metal such as an aluminum alloy, copper, iron, or stainless steel, or a resin having a property of not transmitting the second mirror reflected light RB2. The second shielding member 39 has a pair of elongated hole-shaped second window portions 39a extending in a semicircular shape centered on a common point, with their open sides facing each other. It is formed through at intervals from each other. The distance DE1 between the second openings 39a is preferably set short as long as the mechanical strength for supporting the circular region surrounded by the second openings 39a can be secured. The diameter D1 of the inner peripheral edge of both the second openings 39a is the same as the diameter D1 of the first opening 36a of the first shielding member 36. The radial position and width of the second opening 39a are set so that, of the second mirror reflected light RB2, the light whose reflection angle in the work W is within the second range is passed as the second passing light PB2. To. Specifically, the second range is a range that exceeds the first set angle SA1 and is equal to or less than the predetermined second set angle SA2. Further, due to the non-formed region of the second opening 39a in the second shielding member 39, the reflection angle of the second mirror reflected light RB2 of the second mirror reflected light RB2 is out of the second range. Some light) is shielded. That is, the second shielding member 39 has a second window portion (both second openings 39a) in an annular region formed by an inner peripheral edge having a diameter D1 and an outer peripheral edge having a diameter D2 larger than the diameter D1. Then, the light incident on the outside of this annular region is shielded. The second set angle SA2 exceeds the maximum light receiving angle θ1 and the maximum projection angle when the light whose reflection angle at the work W is the second set angle SA2 among the return light FB returns to the emission end of the optical fiber 90. It is set to be incident on the optical fiber 90 at an incident angle that exceeds θ3 and is equal to or less than the maximum incident angle θ2. The maximum projection angle θ3 is the maximum value of the incident angle of light that can propagate in the clad 92 of the optical fiber 90 in the opposite direction. The maximum incident angle θ2 is the maximum value of the incident angle of light that can be incident on the protective layer 93 of the optical fiber 90. The maximum incident angle θ2 may be set to a predetermined angle that exceeds the maximum projection angle θ3. Therefore, the diameter D2 of the outer peripheral edge of the second opening 39a exceeds the diameter of the incident beam of light that can propagate in the opposite direction through the clad 92 of the optical fiber 90.

A third condensing lens 40 is arranged in parallel with the second shielding member 39 at a position separated from the second shielding member 39 in the emission direction of the second mirror reflected light RB2. The optical axis OA3 of the third condenser lens 40 coincides with the center of both second openings 39a (the optical axis of the second mirror reflected light RB2).

A second optical sensor 41 is arranged at a position away from the third condenser lens 40 in the emission direction of the second mirror reflected light RB2 with its light receiving surface facing the third condenser lens 40. Has been done. The light receiving surface of the second optical sensor 41 is preferably located at the focal point of the third condenser lens 40, but this is not the case. The amount of light detected by the second optical sensor 41 is the amount of light of the second passing light PB2.

The manipulator 60 has a servomotor (not shown) and an encoder (not shown) for each joint axis.

The controller 70 has a control unit 71 and a display unit 72.

The control unit 71 is configured to control the laser light output of the laser oscillator 80 according to the input control program.

Further, the control unit 71 transmits a position command to the servomotor (not shown) provided in the manipulator 60 according to the feedback signal from the control program and the encoder (not shown) provided in the manipulator 60, and the servomotor Control the rotation speed and the amount of rotation (not shown).

Further, as shown in FIG. 5A, the control unit 71 causes the display unit 72 to display and output a warning when the amount of light detected by the first optical sensor 38 exceeds a predetermined first warning threshold value Vfa1. .. Further, the control unit 71 refers to the laser oscillator 80 with respect to the laser when the amount of light detected by the first optical sensor 38 exceeds a predetermined first stop threshold value Vfs1 larger than the first warning threshold value Vfa1. Controls to stop oscillation.

Further, as shown in FIG. 5B, the control unit 71 causes the display unit 72 to display and output a warning when the amount of light detected by the second optical sensor 41 exceeds a predetermined second warning threshold value Vfa2. .. Further, the control unit 71 refers to the laser oscillator 80 with respect to the laser when the amount of light detected by the second optical sensor 41 exceeds a predetermined second stop threshold value Vfs2, which is larger than the second warning threshold value Vfa2. Controls to stop oscillation.

The display unit 72 is configured to display the output state of the laser oscillator 80, the operating state of the manipulator 60, a warning, and the like under the control of the control unit 71.

Then, in the laser processing apparatus 100 configured as described above, the laser oscillator 80 emits the laser light LB. The emitted laser light LB is guided to the laser processing head 30 by the optical fiber 90. Then, the laser beam LB is emitted from the emission end of the optical fiber 90 as an emission beam OB, parallelized by the collimating lens 31, and incident on the first mirror 34 as the collimating beam CB. The collimated beam CB transmitted through the first mirror 34 is focused by the first focusing lens 32 and emitted as a processed beam PB. The processed beam PB emitted from the first condenser lens 32 passes through the protective glass 33 and is irradiated to the work W, and a part of the processed beam PB is reflected from the work W. The reflected light reflected from the work W passes through the first condenser lens 32 and is incident on the first mirror 34. Then, a part of the reflected light that has reached the first mirror 34 passes through the first mirror 34 as return light FB and is incident on the exit end of the optical fiber 90 by the collimating lens 31. This light propagates in the optical fiber 90, and a plurality of laser processing devices 100 such as the inside of the laser oscillator 80, the connection portion of the optical fiber 90, and the protective layer 93 arranged on the outer periphery of the clad 92 shown in FIG. It is incident on the spot. FIG. 6 shows the return lights FB1, FB2 and FB3. The return light FB1 is light whose reflection angle in the work W is equal to or less than the first set angle SA1. The return light FB1 is incident on the optical fiber 90 at an incident angle equal to or less than the maximum light receiving angle θ1 of the optical fiber 90, propagates in the core 91, and is incident on the inside of the laser oscillator 80. Further, the return light FB2 is light whose reflection angle in the work W is equal to or less than the third set angle SA3 and exceeds the first set angle SA1. The return light FB2 is incident on the optical fiber 90 at an incident angle that exceeds the maximum light receiving angle θ1 and is equal to or less than the maximum projection angle θ3, propagates in the cladding 92, and is incident on the inside of the laser oscillator 80. The return light F3 is light whose reflection angle in the work W exceeds the third set angle SA3 and is equal to or less than the second set angle SA2. The return light FB3 is incident on the optical fiber 90 at an incident angle exceeding the maximum projection angle θ3, passes through the clad 92, and then is incident on the protective layer 93. The return light FB3 in this range passes through the protective layer 93 of the optical fiber 90, is absorbed by the protective layer 93, and is converted into heat. Although not shown in FIG. 6, the exit end of the optical fiber 90 usually includes a light absorbing structure that penetrates the clad 92 and absorbs the return light FB3 that can enter the protective layer 93. The light absorption structure converts this return light FB3 into heat. Further, by cooling the light absorbing structure with cooling water, the risk of the return light FB3 not damaging the optical fiber 90 is avoided. On the other hand, a part of the reflected light that has reached the first mirror 34 is reflected by the first mirror 34 and is incident on the second mirror 35 as the first mirror reflected light RB1. A part of the first mirror reflected light RB1 incident on the second mirror 35 passes through the second mirror 35 as the second mirror transmitted light TB2 and is incident on the first shielding member 36. Then, among the second mirror transmitted light TB2 incident on the first shielding member 36, the light whose reflection angle in the work W is equal to or less than the first set angle SA1 passes through the first opening 36a as the first passing light PB1. , The second condensing lens 37 condenses the light so as to focus on the light receiving surface of the first optical sensor 38. On the other hand, a part of the first mirror reflected light RB1 incident on the second mirror 35 is reflected by the second mirror 35 as the second mirror reflected light RB2 and is incident on the second shielding member 39. Then, of the second mirror reflected light RB2 incident on the second shielding member 39, the light whose reflection angle in the work W exceeds the first set angle SA1 and is equal to or less than the second set angle SA2 is the second opening 39a. Is passed as the second passing light PB2, and is condensed by the third condensing lens 40 so as to be focused on the light receiving surface of the second optical sensor 41. As a result, the amount of light detected by the first optical sensor 38 is a value corresponding to the amount of light of the return light FB1 whose reflection angle in the work W is equal to or less than the first set angle SA1, that is, the amount of light that can propagate through the core 91. It becomes. The amount of light detected by the second optical sensor 41 is the amount of light of the return lights FB2 and FB3 whose reflection angle in the work W exceeds the first set angle SA1 and is equal to or less than the second set angle SA2, that is, the clad 92 and the protective layer. The value corresponds to the amount of light that can propagate in 93. Therefore, the amount of incident light of the return light FB1 that can propagate through the core 91 and reach the inside of the laser oscillator 80, and propagate through the clad 92 or the protective layer 93 to reach the end face of the optical fiber 90 or the inside of the laser oscillator 80. The amount of incident light of the return light FB2 and FB3 can be measured individually. As described above, the return light FB3 that can be incident on the protective layer 93 is absorbed by the light absorption structure provided at the exit end of the optical fiber 90. However, if the return light FB3 increases too much, it cannot be completely absorbed by the light absorption structure.

Then, when the amount of light detected by the first optical sensor 38 exceeds the first warning threshold value Vfa1, the display unit 72 displays and outputs a warning under the control of the control unit 71. Further, even when the amount of light detected by the second optical sensor 41 exceeds the second warning threshold value Vfa2, the display unit 72 displays and outputs a warning under the control of the control unit 71. Further, when the amount of light detected by the first optical sensor 38 exceeds the first stop threshold value Vfs1, the laser oscillator 80 stops the laser oscillation under the control of the control unit 71. Further, even when the amount of light detected by the second optical sensor exceeds the second stop threshold value Vfs2, the laser oscillator 80 stops the laser oscillation under the control of the control unit 71. For example, the first warning threshold value Vfa1 and the first stop threshold value Vfs1 are individually set to values corresponding to the locations where the return light FB1 passes through the core 91 and is incident in the opposite direction, that is, the internal structure of the laser oscillator 80. May be done. As a result, damage to the laser oscillator 80 can be reliably suppressed, and it is possible to prevent the warning output and the stop of the laser oscillation from being wasted when the laser oscillator 80 can tolerate more incident light. Further, the second warning threshold value Vfa2 and the second stop threshold value Vfs2 are the internal structure of the portion where the return light FB2 and FB3 pass through the clad 92 and enter in the opposite direction, and the protective layer 93 and the light absorption structure. The values may be set individually according to the characteristics. As a result, damage to the optical fiber 90 or the laser oscillator 80 is surely suppressed, and the warning output and the stop of the laser oscillation are wasted in a state where the optical fiber 90 or the laser oscillator 80 can tolerate more incident light. Can be prevented.

(Embodiment 2)
In the second embodiment, as shown in FIG. 7, a third mirror 42 is arranged between the first mirror 34 and the second mirror 35 in parallel with the first mirror 34 and the second mirror 35. The third mirror 42 transmits a part of the first mirror reflected light RB1 as the third mirror transmitted light TB3, and reflects the rest of the first mirror reflected light RB1 as the third mirror reflected light RB3. Then, a part of the third mirror transmitted light TB3 is transmitted through the second mirror 35 as the second mirror transmitted light TB2, and the rest of the third mirror transmitted light TB3 is reflected by the second mirror 35 as the second mirror reflected light RB2. To do. Therefore, the reflected light reflected from the work W by the first mirror 34, the second mirror 35, and the third mirror 42 and passed through the first condensing lens 32 is used as the return light FB and the first divided light. An optical system that divides the light into the second mirror transmitted light TB2, the second mirror reflected light RB2 as the second divided light, and the third mirror reflected light RB3 as the third divided light is configured. The reflectance of the first mirror reflected light RB1 in the third mirror 42 is not particularly limited, but may be set to 50% so that the third mirror transmitted light TB3 and the third mirror reflected light RB3 are substantially equal. desirable. Further, as shown in FIG. 8, the width of the second opening 39a of the second shielding member 39 is narrower than that of the first embodiment. Specifically, regarding the position and width of the second opening 39a in the radial direction, the reflection angle of the work W in the second mirror reflected light RB2 exceeds the first set angle SA1 and is equal to or less than the third set angle SA3. The light is set to pass as the second passing light PB2. Therefore, in the second embodiment, the second range is a range that exceeds the first set angle SA1 and is equal to or less than the third set angle SA3. The second range corresponds to the range of the return light FB2 that can propagate in the opposite direction through the clad 92 of the optical fiber 90. Therefore, the diameter D3 of the outer peripheral edge of the second opening 39a corresponds to the maximum diameter of the incident beam that can propagate through the clad 92 of the optical fiber 90 as a whole. Needless to say, the diameter D1 of the inner peripheral edge of the second opening 39a corresponds to the maximum diameter of the incident beam that can propagate through the core 91 of the optical fiber 90, and is equal to the diameter D1 of FIG.

Further, at a location separated from the third mirror 42 in the emission direction of the third mirror reflected light RB3, the square plate-shaped third shielding member 43 shown in FIG. 9 is perpendicular to the optical axis of the third mirror reflected light RB3. It is arranged in a state. The third shielding member 43 is also made of a metal such as an aluminum alloy, copper, iron, or stainless steel, or a resin having a property of not transmitting the third mirror reflected light RB3. The third shielding member 43 has a pair of elongated hole-shaped third openings 43a as a third window portion extending in a semicircular shape centered on a common point, with their open sides facing each other. It is formed through at intervals from each other. The distance DE1 between the third openings 43a is preferably set short as long as the mechanical strength for supporting the circular region surrounded by the third openings 43a can be secured. The diameter D3 of the inner peripheral edge of both third openings 43a is equal to the diameter D3 of the outer peripheral edge of the second opening 39a of the second shielding member 39. The radial position and width of the third opening 43a are set so that the light of the third mirror reflected light RB3 whose reflection angle in the work W is within the third range is passed as the third passing light PB3. To. Further, the remaining portion of the third mirror reflected light RB3 (that is, the light whose reflection angle in the work W is outside the third range) is shielded by the third opening 43a non-forming region in the third shielding member 43. Specifically, the third range is a range that exceeds the third set angle SA3 and is equal to or less than the second set angle SA2. The diameter D2 of the outer peripheral edge of both third openings 43a is equal to the diameter D2 of the outer peripheral edge of the second opening 39a.

A fourth condensing lens 44 is arranged in parallel with the third shielding member 43 at a position separated from the third shielding member 43 in the emission direction of the third mirror reflected light RB3. The optical axis OA4 of the fourth condenser lens 44 coincides with the center of both third openings 43a (the optical axis of the third mirror reflected light RB3).

A third optical sensor 45 is arranged at a position away from the fourth condensing lens 44 in the emission direction of the third mirror reflected light RB3 with its light receiving surface facing the fourth condensing lens 44. Has been done. The light receiving surface of the third optical sensor 45 is preferably located at the focal point of the fourth condenser lens 44, but this is not the case. Therefore, the amount of light detected by the third optical sensor 45 is the amount of light of the third passing light PB3, that is, the amount of light of the return light FB3 that can pass through the protective layer 93 of the optical fiber 90.

Further, the control unit 71 of the controller 70 causes the display unit 72 to display and output a warning even when the amount of light detected by the third optical sensor 45 exceeds a predetermined third warning threshold value. Further, even when the amount of light detected by the third optical sensor 45 exceeds a predetermined third stop threshold value larger than the third warning threshold value, the laser oscillator 80 is controlled to stop the laser oscillation. Do.

Since the other configurations are the same as those in the first embodiment, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

In the second embodiment, for example, the second warning threshold value Vfa2 and the second stop threshold value Vfs2 are internal structures (laser oscillators) of locations where the return light FB2 passes through the clad 92 of the optical fiber 90 and is incident in the opposite direction. The value may be set according to the internal structure of 80). As a result, damage to the laser oscillator 80 can be reliably suppressed, and it is possible to prevent the laser oscillator 80 from outputting a warning or stopping the laser oscillation in a state where more incident light can be tolerated. Further, the third warning threshold value and the third stop threshold value may be set to values according to the location where the return light FB3 is incident, that is, the characteristics of the protective layer 93 and the light absorption structure. As a result, damage to the optical fiber 90 can be reliably suppressed, and it is possible to prevent the output of the warning and the stop of the laser oscillation from being wasted in a state where the optical fiber 90 can tolerate more incident light.

(Embodiment 3)
In the third embodiment, as shown in FIGS. 10 and 11, the first shielding member 36 is a square first plate-shaped member 36b made of translucent glass or resin, and the first plate-shaped member 36b. It is composed of a translucent first coating layer 36c formed in a region excluding the central portion on one surface. The first coating layer 36c is made of a metal or resin having a property of not transmitting the second mirror transmitted light TB2. The non-formed region of the first coating layer 36c of the first plate-shaped member 36b constitutes the first window portion 36d having translucency. The region of the first window portion 36d corresponds to the region of forming the first opening portion 36a of the first embodiment. Similarly, the second shielding member 39 is also a region excluding a square second plate-shaped member 39b made of translucent glass or resin and an annular region on one surface of the second plate-shaped member 39b. It is composed of a translucent second coating layer 39c formed in. The second coating layer 39c is made of a metal or resin having a property of not transmitting the second mirror reflected light RB2. The non-formed region of the second coating layer 39c of the second plate-shaped member 39b constitutes the second window portion 39d having translucency. The region of the second window portion 39d corresponds to the formation region of the second opening portion 39a of the first embodiment.

Since the other configurations are the same as those in the first embodiment, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

In the second embodiment as well, as the first shielding member 36, the second shielding member 39, and the third shielding member 43, the translucent plate-shaped member is coated with the impermeable coating layer as in the third embodiment. You may use the one which formed.

Further, in the above-described first and third embodiments, the first shielding member 36 and the second shielding member 39 have a square plate shape, but other shapes such as a rectangular plate shape and a circular plate shape may be used. Similarly, in the second embodiment, the third shielding member 43 may have a shape other than the square plate shape.

In the first embodiment, the laser processing head 30 detects the amount of light in the first range from the second mirror transmitted light TB2, and detects the amount of light in the second range from the second mirror reflected light RB2. doing. Not limited to this, the laser processing head 30 may detect the amount of light in the second range from the second mirror transmitted light TB2 and detect the amount of light in the first range from the second mirror reflected light RB2. Good. In the second embodiment, the laser processing head 30 detects the amount of light in the first range from the second mirror transmitted light TB2, and detects the amount of light in the second range from the second mirror reflected light RB2. The amount of light within the third range from the third mirror reflected light RB3 is detected. Not limited to this, the laser processing head 30 detects, for example, the amount of light in the range from the second mirror transmitted light TB2 to the third range, and detects the amount of light in the first range from the second mirror reflected light RB2. , The amount of light within the second range from the third mirror reflected light RB3 may be detected.

As described above, in the present disclosure, the incident light amount of the return light at a plurality of locations of the laser processing apparatus can be individually acquired, and the degree of danger can be predicted or warned according to the permissible value of the incident light amount at each location. It is extremely useful and highly industrially useful because it has a highly practical effect.

30 Laser processing head 31 Collimating lens 32 First condensing lens 34 First mirror (optical system)
35 Second mirror (optical system)
36 First shielding member 36a First opening (first window)
36d 1st window 38 1st optical sensor 39 2nd shielding member 39a 2nd opening (2nd window)
39d 2nd window 41 2nd optical sensor 42 3rd mirror (optical system)
43 Third shielding member 43a Third opening (third window)
45 Third optical sensor 70 Controller 80 Laser oscillator 90 Optical fiber 91 Core 93 Protective layer 100 Laser processing device LB Laser light FB Return light TB2 Second mirror transmitted light (first division light)
RB2 2nd mirror reflected light (2nd divided light)
RB3 3rd mirror reflected light (3rd division light)
PB1 1st passing light PB2 2nd passing light PB3 3rd passing light Vfa1 1st warning threshold Vfs1 1st stop threshold Vfa2 2nd warning threshold Vfs2 2nd stop threshold θ1 Maximum light receiving angle θ2 Maximum incident angle θ3 Maximum projection Corner W work

Claims (10)

A laser processing head that emits laser light emitted by a laser oscillator and passed through an optical fiber toward a workpiece.
A collimating lens that parallelizes the laser beam emitted from the optical fiber and
A condenser lens that collects the laser beam parallelized by the collimating lens and emits it toward the work.
An optical system that divides the reflected light reflected from the work and parallelized by the condenser lens into a plurality of divided lights including a return light returning to the collimating lens, a first divided light, and a second divided light.
A first window portion is formed to allow light having a reflection angle within the first range of the work among the first divided light to pass as the first passing light, and the reflected light of the first divided light in the work is reflected. A first shielding member that shields light whose corners are outside the first range,
Of the second divided light, a second window portion is formed to allow light having a reflection angle in the work within a second range different from the first range to pass as the second passing light, and the second divided light is formed. Of the light, a second shielding member that shields the light whose reflection angle in the work is outside the second range, and
The first optical sensor that detects the amount of light of the first passing light and
A laser processing head including a second optical sensor that detects the amount of light of the second passing light. In the laser processing head according to claim 1,
Of the return light, light whose reflection angle in the work is within the first range is incident on the optical fiber at an incident angle equal to or less than the maximum light receiving angle of light that can propagate through the core of the optical fiber. Of the return light, the light whose reflection angle in the work is within the second range exceeds the maximum light receiving angle and is incident at least the maximum incident angle of light that can be incident on the protective layer of the optical fiber. A laser processing head characterized in that it is incident on the optical fiber at an angle. In the laser processing head according to claim 2,
The plurality of divided lights further include a third divided light.
The laser processing head is a third window through which, of the third divided light, light whose reflection angle in the work is in a third range different from the first and second ranges is passed as the third passing light. A third shielding member for which a portion is formed and shields the rest of the third divided light,
A third optical sensor for detecting the amount of the third passing light is further provided.
Of the return light, the light whose reflection angle in the work is within the second range exceeds the maximum light receiving angle and is equal to or less than the maximum projection angle of light capable of propagating through the clad of the optical fiber. Of the return light that is incident on the optical fiber, the light whose reflection angle in the work is within the third range exceeds the maximum projection angle and is equal to or less than the maximum incident angle. A laser processing head characterized by being incident on an optical fiber. The laser processing head according to any one of claims 1 to 3 and
With the laser oscillator
With the optical fiber
When the amount of light detected by the first optical sensor exceeds a predetermined first threshold value, and when the amount of light detected by the second optical sensor exceeds a predetermined second threshold value. A laser processing apparatus including a controller that performs a predetermined process. In the laser processing apparatus according to claim 4,
A laser processing apparatus characterized in that the predetermined processing is a warning output. In the laser processing apparatus according to claim 4,
The laser processing apparatus, wherein the predetermined process is a control for stopping the laser oscillation of the laser oscillator. A laser machining control method using a laser machining apparatus including the laser machining head according to any one of claims 1 to 3, the laser oscillator, and the optical fiber.
When the amount of light detected by the first optical sensor exceeds a predetermined first threshold value, and when the amount of light detected by the second optical sensor exceeds a predetermined second threshold value. A laser processing control method characterized by performing a predetermined process. The laser processing head according to claim 1.
The optical system is
It is arranged between the collimating lens and the condensing lens, receives the reflected light, transmits a part of the reflected light as the return light, and the remaining part of the reflected light is the first divided light. And the first mirror, which is reflected as the first mirror reflected light including the second divided light,
In response to the first mirror reflected light, the first divided light in the first mirror reflected light is directed to the first shielding member, and the second divided light in the first mirror reflected light is directed to the second shielding member. The second mirror facing the member,
Laser machining head equipped with. The laser processing head according to claim 1.
The first range is a range in which the reflection angle of the work is 0 degrees or more and is equal to or less than the first set angle.
The second range is a range in which the reflection angle of the work exceeds the first set angle and is equal to or less than the second set angle larger than the first set angle.
Laser machining head. The laser processing head according to claim 1.
The first shielding member has the first window portion in a circular region having a first diameter, and shields light incident on the outside of the circular region.
The second shielding member has the second window portion in an annular region formed by an inner peripheral edge having the first diameter and an outer peripheral edge having a second diameter larger than the first diameter. , Shields light incident outside the annular region,
Laser machining head.

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