Patent Application
20220118557
The present invention relates to a laser processing head that emits a laser beam emitted by a laser oscillator toward a workpiece, and a laser processing device including the laser processing head.
PTL 1 discloses a laser processing head that emits a laser beam emitted by a laser oscillator toward a workpiece through a protective glass. The laser processing head includes a shield holder, an optical sensor attached to the shield holder, and the protective glass provided on the shield holder. The shield holder includes an opening formed through the shield holder, and a light passing hole formed in an inner peripheral surface of the opening. The optical sensor is attached to the shield holder while having a light receiving surface facing the inside of the opening through the light passing hole. The protective glass is provided in the opening of the shield holder while having an outer peripheral surface facing the light receiving surface of the optical sensor. In this laser processing head, a part of the laser beam emitted by the laser oscillator is scattered by contamination adhering to a front surface of the protective glass and reflected by the front surface, a back surface, and the outer peripheral surface of the protective glass, and the inner peripheral surface of the opening of the shield holder. The reflected laser beam is emitted from an opposed region on the outer peripheral surface of the protective glass, the opposed region facing the light receiving surface of the optical sensor. Then, the amount of scattered light emitted from the opposed region is detected by the optical sensor as a numerical value indicating a degree of contamination on the front surface of the protective glass.
PTL 1: Japanese Translation of PCT International Application No. 2002-515341
Unfortunately, the outer peripheral surface of the protective glass and the inner peripheral surface of the opening of the shield holder disclosed in PTL 1 are generally low in reflectance, so that fine contamination adhering to the front surface of the protective glass may not be reflected in a detection value of the optical sensor.
The present invention has been made in view of such a point, and an object of the present invention is to enable finer contamination to be reflected in a detection value of an optical sensor and enable contamination on a protective glass to be detected at an early stage.
To achieve the above object, the present invention provides a laser processing head including: a shield holder that has an opening formed through the shield holder and at least one light passing hole formed in an inner peripheral surface of the opening; at least one optical sensor that has a light receiving surface facing the inside of the opening through the at least one light passing hole and is attached to the shield holder; and a protective glass that has an outer peripheral surface facing the light receiving surface of the at least one optical sensor and is provided in the opening of the shield holder, the protective glass transmitting a laser beam emitted by a laser oscillator to emit the laser beam toward a workpiece, and the protective glass including a reflective coating film formed in a region in the outer peripheral surface except an opposed region facing the light receiving surface of the at least one optical sensor, or the shield holder including the reflective coating film formed in a region in the inner peripheral surface of the opening except the light passing hole.
This configuration increases reflectance on the outer peripheral surface of the protective glass or the inner peripheral surface of the opening of the shield holder as compared with the case where the reflective coating film is not formed on the outer peripheral surface of the protective glass or the inner peripheral surface of the opening of the shield holder, so that the amount of scattered light incident on the light receiving surface of the optical sensor increases. Thus, as compared with the case where the reflective coating film is not formed on the outer peripheral surface of the protective glass or the inner peripheral surface of the opening of the shield holder, finer contamination can be reflected in a detection value of the optical sensor, and thus contamination on the protective glass can be detected at an early stage.
The present invention enables finer contamination to be reflected in the detection value of the optical sensor, and enables contamination on the protective glass to be detected at an early stage.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred exemplary embodiments is inherently only an example and is not intended at all to limit the present invention, applications of the present disclosure, or use of the present invention.
In the following description, the term, “aligning”, means not only strict aligning but also aligning reflecting assembly tolerance and processing tolerance in manufacturing.
Laser processing head 50 irradiates workpiece W with laser beam LB from optical fiber 90. Laser processing head 50 is attached to a leading end of manipulator 60. Manipulator 60 moves laser processing head 50. Controller 70 controls operation of laser processing head 50, operation of manipulator 60, and laser oscillation of laser oscillator 80. Laser oscillator 80 generates laser beam LB by oscillation and emits laser beam LB to optical fiber 90. Optical fiber 90 guides laser beam LB emitted from laser oscillator 80 to laser processing head 50. The configuration described above allows laser processing device 100 to irradiate workpiece W with laser beam LB emitted from laser oscillator 80 along a desired trajectory by operating laser processing head 50 and manipulator 60.
Laser processing device 100 is used to weld workpiece W.
As illustrated in
Lens case 2 is provided inside with lens holder 5 in a substantially tubular shape that is disposed substantially along lens case 2. Lens holder 5 is provided inside near its end portion on a side close to body case 3 with collimation lens 6 and focus lens 7 that are disposed from a side opposite to body case 3 while having front and back surfaces facing an axial direction of lens holder 5. Inside lens holder 5, emission end A of optical fiber 90 is located. Collimation lens 6 collimates laser beam LB emitted from emission end A of optical fiber 90 and spread. Focus lens 7 concentrates laser beam LB collimated by collimation lens 6 to focus laser beam LB on near a processing point on workpiece W.
Body case 3 is provided inside with first and second holders 8, 9 each in a substantially tubular shape that are disposed in order from a side close to lens case 2 substantially along body case 3. Inside first holder 8, first parallel plate 10 is fixed. First holder 8 is provided on its outer peripheral side with first belt pulley 11 disposed with its axial direction oriented in an axial direction of first holder 8. First belt pulley 11 is attached to first servomotor 12 that rotates first belt pulley 11. To first belt pulley 11 and first holder 8, first timing belt 13 is attached. Thus, first holder 8 can be rotated by rotating first belt pulley 11 with first servomotor 12. First servomotor 12 is provided around its periphery with first encoder (illustrated in only
Inside second holder 9, second parallel plate 15 is fixed. Second holder 9 is provided on its outer peripheral side with second belt pulley 16 disposed with its axial direction oriented in an axial direction of second holder 9. Second belt pulley 16 is attached to second servomotor 17 that rotates second belt pulley 16. To second belt pulley 16 and second holder 9, second timing belt 18 is attached. Thus, second holder 9 can be rotated by rotating second belt pulley 16 with second servomotor 17. Second servomotor 17 is provided around its periphery with second encoder (illustrated in only
Inner nozzle 4 is provided near its end portion on a side close to inlet 4a with first protective glass 20 that is disposed with front and back surfaces facing an axial direction of inner nozzle 4. Inner nozzle 4 is provided in its part in a circumferential direction slightly closer to outlet 4b than first protective glass 20 with holder insertion port 4c that is formed passing through the part and extending in the circumferential direction. Inner nozzle 4 is also provided in its inner peripheral surface near the end portion on the side close to inlet 4a with stepped portion 4d that is formed over the entire periphery excluding holder insertion port 4c while having an inner edge on a side close to outlet 4b that is positioned inward from that on a side close to inlet 4a. Inner nozzle 4 is provided on its outer peripheral side with nozzle holder 21 in a substantially tubular shape that is disposed to cover an outer peripheral surface of inner nozzle 4 in a region from a portion slightly below an end edge of inner nozzle 4 on a side close to inlet 4a toward outlet 4b to a substantial center in the axial direction. Nozzle holder 21 is provided on its side close to outlet 4b with outer nozzle 22 that is disposed to cover an end portion of inner nozzle 4 on the side close to outlet 4b from an outer peripheral side.
Into holder insertion port 4c of inner nozzle 4, shield holder 23 in a substantially rectangular plate-like shape illustrated in
In opening 23b of shield holder 23, second protective glass 25 in a circular plate-like shape, which is also illustrated in
In opening 23b of shield holder 23, pressing ring 26 in an annular plate-like shape is disposed to press an outer peripheral portion of second protective glass 25 from both sides in a direction passing through opening 23b along with ridge portion 23d. Pressing ring 26 is made of, for example, an aluminum alloy, a steel material, or stainless steel. Pressing ring 26 has an outer peripheral surface on which a male thread (not illustrated) is cut, and the male thread is screwed with the female thread in the inner peripheral surface of opening 23b of shield holder 23. Shield holder 23, optical sensor 24, second protective glass 25, and pressing ring 26 constitute protective glass unit 27. Thus, protective glass unit 27 can be integrally assembled by inserting optical sensor 24 into optical sensor mounting hole 23c of shield holder 23 and screwing the male thread of pressing ring 26 with the female thread of shield holder 23 while second protective glass 25 is placed on ridge portion 23d of shield holder 23. Pressing ring 26 is not limited to a circular shape, and may have an outer shape of a polygon such as a triangle, a square, or a hexagon.
As illustrated in
Controller 70 includes control unit 71, display 72, and input unit 73.
Control unit 71 is configured to control output of a laser beam from laser oscillator 80 according to a control program received from input unit 73.
Control unit 71 controls rotation speed and the amount of rotation of first and second servomotors 12, 17 by transmitting a rotation command to first and second servomotors 12, 17 according to the control program received from input unit 73 and feedback signals from first and second encoders 14, 19 provided in laser processing head 50.
Control unit 71 also controls rotation speed and the amount of rotation of servo motor 61 by transmitting a position command to servo motor 61 provided in manipulator 60 according to the control program received from input unit 73 and a feedback signal from encoder 62 provided in manipulator 60.
As illustrated in
Display 72 is configured to display an output state of laser oscillator 80, an operation state of manipulator 60, a warning, and the like under control of control unit 71.
Input unit 73 is configured to set an output of laser oscillator 80 and an input of a control program for determining movement speed and the amount of movement of manipulator 60. Input unit 73 is also configured to set an input of a control program or the like for determining rotation speed and rotation time of first and second servomotors 12, 17.
Controller 70 may be provided with a teaching pendant that creates (teaches) and executes programs, and the teaching pendant may implement functions of display 72 and input unit 73. The teaching pendant also may create the control program.
Then, laser processing device 100 described above is configured such that when laser oscillator 80 emits laser beam LB, emitted laser beam LB is guided to laser processing head 50 through optical fiber 90. Laser beam LB guided to laser processing head 50 is collimated by collimation lens 6 and then concentrated by focus lens 7. First and second parallel plates 10, 15 adjust an optical axis of laser beam LB having passed through focus lens 7, and then laser beam LB passes through first protective glass 20 and second protective glass 25 to irradiate workpiece W. Then, when contamination D adheres to front surface 25b of second protective glass 25 as illustrated in
Another structure is identical to that of the first exemplary embodiment, so that the same components are denoted by the same reference numerals and duplicated detailed description thereof will be eliminated.
Thus, reflective coating films 23e, 26a are respectively formed on shield holder 23 and pressing ring 26 that are to be replaced less frequently than second protective glass 25 in the second exemplary embodiment, so that costs can be reduced as compared with the case where reflective coating film 25a is formed on second protective glass 25 as in the first exemplary embodiment.
Additionally, reflective coating film 23e is also formed on the surface of ridge portion 23d of shield holder 23 on the side close to outlet 4b and the surface of pressing ring 26 on the side close to inlet 4a, so that the reflectance on the surface of ridge portion 23d on the side close to outlet 4b and the surface of pressing ring 26 on the side close to inlet 4a increases as compared with the case where the reflective coating film is formed only on the inner peripheral surface of opening 23b of shield holder 23, thereby increasing the amount of scattered light SL to be incident on light receiving surface 24a of optical sensor 24. Thus, finer contamination can be reflected in a detection value of optical sensor 24, and as a result, the timing of output of a warning due to contamination adhering to second protective glass 25 and the timing of stopping laser oscillation can be more appropriately controlled.
Although the first and second exemplary embodiments cause controller 70 to output a warning display when the amount of light detected by optical sensor 24 exceeds first threshold value Vsca1, a warning sound may be output, or a warning signal received by a device outside controller 70 may be output.
Although the first and second exemplary embodiments cause controller 70 to perform processing of outputting a warning when the amount of light detected by optical sensor 24 exceeds first threshold value Vsca1, another predetermined processing may be performed. Similarly, although controller 70 is caused to perform processing of stopping laser oscillation of laser oscillator 80 when the amount of light detected by optical sensor 24 exceeds second threshold value Vsca2, another predetermined processing may be performed.
Although one set of optical sensor mounting hole 23c and optical sensor 24 is provided in the first and second exemplary embodiments, a plurality of sets may be provided. When detection values of the plurality of optical sensors 24 satisfy predetermined conditions, controller 70 may perform predetermined processing such as outputting a warning and performing control of stopping laser oscillation of laser oscillator 80.
Although in the second exemplary embodiment, reflective coating film 23e is formed on the region of the inner peripheral surface of opening 23b of shield holder 23 except optical sensor mounting hole 23c and the surface of ridge portion 23d on the side close to outlet 4b, reflective coating film 23e may not be provided on the surface of ridge portion 23d on the side close to outlet 4b.
Although in the second exemplary embodiment, reflective coating film 26a is formed over the entire surface of pressing ring 26 on the side close to inlet 4a, reflective coating film 26a may not be formed.
The laser processing head of the present invention can reflect finer contamination on a detection value of the optical sensor, and is useful for application to a laser processing device.
23: shield holder
23
b: opening
23
c: optical sensor mounting hole (light passing hole)
23
d: ridge portion
23
e: reflective coating film
24: optical sensor
24
a: light receiving surface
25: second protective glass
25
a: reflective coating film
25
b: front surface of second protective glass
25
c: back surface of second protective glass
25
d: outer peripheral surface of second protective glass
25
e: opposed region in outer peripheral surface of second protective glass
25
f: region in outer peripheral surface of second protective glass except opposed region
26: pressing ring
26
a: reflective coating film
50: laser processing head
70: controller
80: laser oscillator
90: optical fiber
100: laser processing device
LB: laser beam
W: workpiece
Vsca1: first threshold value
Vsca2: second threshold value
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-103835 | Jun 2019 | JP | national |
This application is a continuation of the PCT International Application No. PCT/JP2020/017623 filed on Apr. 24, 2020, which claim the benefit of foreign priority of Japanese patent application No. 2019-103835 filed on Jun. 3, 2019, the contents all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/017623 | Apr 2020 | US |
| Child | 17531291 | US |
