JP6122347B2 - Method for detecting dirt on protective glass and laser processing head - Google Patents

Description

  The present invention relates to a method for detecting dirt on a protective glass provided in a laser processing head and a laser processing head. More specifically, the present invention relates to a method for detecting dirt on a protective glass by irradiating detection light from the outer peripheral surface of the protective glass, detecting the amount of detection light reflected from the outer peripheral surface and leaked from the outer peripheral surface, and a laser processing head. .

  A laser processing head in a laser processing machine is provided with a condensing lens that condenses laser light emitted from a laser oscillator and irradiates the workpiece. When laser processing is performed on a workpiece by irradiating the workpiece with laser light, spatter and fumes generated during the laser processing may scatter around and contaminate the condenser lens. When spatter or the like adheres to the condensing lens and is contaminated, the condensing lens is severely deteriorated. Therefore, a protective glass is provided in the laser processing head in order to protect the condenser lens from contaminants such as spatter and fumes.

  As described above, in the configuration including the protective glass, the condensing lens can be protected from sputtering or the like, but the protective glass is contaminated. Therefore, means for protecting the protective glass from contaminants such as spatter and fumes generated during laser processing are taken, and means for detecting contamination of the protective glass are taken (see, for example, Patent Document 1).

JP 2013-52440 A

  The configuration of the laser processing head described in Patent Document 1 is as shown in FIG. In other words, the conventional laser processing head 1 is appropriately attached to the head support member 3 that can move in the X, Y, and Z axis directions, such as a robot arm, through the attachment attachment 5. That is, the laser processing head 1 includes a processing head main body 7, and a support bracket 9 provided in the processing head main body 7 is connected to the attachment attachment 5.

  An optical fiber receiver 11 is provided on the upper end side of the processing head body 7, and the other end portion of the optical fiber F having one end connected to a laser oscillator (not shown) is connected to the optical fiber receiver 11. . A collimating lens 13 for collimating the laser beam LB emitted from the optical fiber F is provided at a position facing the other end of the optical fiber F.

  The laser beam LB converted into parallel rays by the collimating lens 13 is bent in the direction of the condensing lens 17 provided by the first reflecting mirror 15 provided in the processing head body 7. Then, the laser beam LB condensed by the condenser lens 17 is bent toward the laser nozzle 21 provided in the processing head body 7 by the second reflecting mirror 19 provided in the processing head body 7 and is a workpiece (not shown). The workpiece is laser processed.

  A protective glass 23 for protecting the second reflecting mirror 19 and the condenser lens 17 from spatter and fumes generated during laser processing is provided above the laser nozzle 21 and below the second reflecting mirror 19. Is provided. In order to detect contamination of the protective glass 23, the protective glass 23 is irradiated on the protective glass 23 from above through the second reflective mirror 19 above the second reflective mirror 19. Irradiation means 25 for irradiating the laser processing position through the laser beam is provided. Furthermore, an imaging means 27 for imaging the laser processing position is provided.

  In order to protect the protective glass 23 from contaminants such as spatter and fumes generated during laser processing, an air curtain is formed between the protective glass 23 and the laser nozzle 21 to blow the contaminants to the outside. Means 29 are provided. That is, a hollow box-shaped casing 31 is provided between the protective glass 23 and the laser nozzle 21, and the casing 31 is provided with an air ejection means 35 connected with an air supply path 33. Yes.

  The air jetting means 35 forms an air curtain in a direction orthogonal to the laser beam LB, and blows the spatter and fumes scattered from the laser processing position toward the protective glass 23 to the outside from the air discharge port 37. It is what you make. An end portion of the optical fiber 39 for detecting the reflected light irregularly reflected from the sputter or the like is appropriately disposed on a part of the outer peripheral surface of the protective glass 23 in order to detect that spatter or fume has adhered. Is connected to.

  In the above configuration, when the workpiece is subjected to laser processing by irradiating the workpiece with the laser beam LB, contaminants such as spatter and fume are generated at the laser processing position. Then, most of the contaminants scattered from the laser processing position toward the protective glass 23 are discharged from the air discharge port 37 to the outside by the air curtain ejected from the air ejection means 25 in the air curtain forming means 29. However, some of the contaminants adhere to the lower surface of the protective glass 23.

  As described above, when a contaminant adheres to the protective glass 23, a part of the light irradiated from above by the irradiation means 25 is irregularly reflected by the contaminant and is emitted from the outer peripheral surface of the protective glass 23 to the outside. When a part of the reflected light emitted to the outside enters the optical fiber 39 and the light quantity of the incident light becomes larger than a preset value, the protection glass 23 is replaced.

  As already understood, light (detection light) for detecting that spatter or the like has adhered to the protective glass 23 is irradiated from above the protective glass 23. Therefore, most of the detection light passes through the protective glass 23. And the light reflected in the lower surface of the said protective glass 23, and irregularly reflected by a contaminant and is radiate | emitted to the outer peripheral surface of the protective glass 23 is detected. Therefore, a slight amount of light is detected, the detection level is low, and it is easily affected by externally incident disturbance, and further improvement has been desired.

  The present invention has been made in view of the problems as described above, and is a method for detecting dirt on a protective glass provided in a laser processing head, and the detection light is incident on the protective glass from the outer peripheral surface of the protective glass, Detecting the amount of detection light reflected from the peripheral surface of the protective glass and diffused by a contaminant attached to the protective glass and leaking from the outer peripheral surface by a light detection means provided on the peripheral surface of the protective glass By this, the dirt on the protective glass is detected.

  Further, in the method for detecting dirt on the protective glass, the detection light is incident on the protective glass within an angle of 45 ° or less between the detection directing direction of the light detection means and the incident direction of the detection light. It is what.

  The laser processing head includes a condensing lens and a protective glass for protecting the condensing lens, and detection light for detecting dirt on the protective glass is incident on the protective glass from the outer peripheral surface of the protective glass. Detection light incident means, and light detection means for detecting the amount of detection light reflected from the peripheral surface of the protective glass and diffused by a contaminant attached to the protective glass and leaked from the outer peripheral surface. It is characterized by that.

  In the laser processing head, an angle formed by an incident direction of the detection light incident unit and a detection directing direction of the light detection unit is 45 ° or less.

  In the laser processing head, air curtain forming means for blowing off spatter and fumes generated during laser processing is provided on the lower side of the protective glass, and corresponds to the downstream side of the air flow by the air curtain forming means. The detection light incident means is arranged at an upstream position where the downstream end side of the protective glass is irradiated.

  In the laser processing head, the protective glass is provided on the upper side of the irradiation means for irradiating the laser processing position.

  According to the present invention, since the detection light enters the protective glass from the outer peripheral surface of the protective glass, the incident detection light is reflected by the upper and lower inner surfaces and the inner peripheral surface of the protective glass. Therefore, even if the incident position of the detection light is one, the detection light is transmitted over the entire inside of the protective glass. And when sputter | spatter etc. adhere, detection light will be irregularly reflected by spatter | spatter etc., and when it radiate | emits outside from the outer peripheral surface of a protective glass, it will be detected by a photon detection means.

  Therefore, the amount of light detected by the light detection means is large, and adhesion such as sputtering can be reliably detected. Further, since the amount of detection light is large, the detection level can be increased and the influence of disturbance can be suppressed.

It is a section explanatory view showing the composition of the principal part of the laser processing head concerning the embodiment of the present invention. It is explanatory drawing of the structure which injects the detection light with respect to protective glass. It is explanatory drawing which shows the positional relationship of a detection light incident means and a light detection means. It is explanatory drawing which shows the structure of the conventional laser processing head.

  Hereinafter, the configuration of the laser processing head according to the embodiment of the present invention will be described with reference to the drawings. Most of the configuration of the laser processing head according to the embodiment is the same as that of the conventional laser processing head described above. Therefore, the structure which detects the stain | pollution | contamination of the protective glass with which the laser processing head was equipped is demonstrated. Note that components having the same functions as those of the laser processing head described above are denoted by the same reference numerals, and redundant description is omitted.

  Referring to FIG. 1, a laser processing head 1A according to an embodiment of the present invention includes a processing head main body 7 provided with a condenser lens (not shown), similar to the conventional laser processing head described above. A glass holder unit 41 detachably provided with a protective glass 23 is provided on the lower side of the processing head body 7, that is, on the laser nozzle (not shown in FIG. 1) side. On the lower side of the glass holder unit 41, an irradiation means 43 is provided in place of the irradiation means 25 described above. A casing 31 </ b> A having the same configuration as the casing 31 described above is provided below the irradiation unit 43.

  The glass holder unit 41 includes an annular unit main body 45 attached to the lower side of the processing head main body 7. In the unit main body 45, a cylindrical glass holder 46 provided with the disk-shaped protective glass 23 is provided. The glass holder 46 is provided with a light transmission hole through which incident light and reflected light can be transmitted at positions corresponding to detection light incident means and light detection means described later.

  The unit main body 45 is provided with an LED 47 as an example of detection light incident means for allowing detection light to enter the protective glass 23 from the outer peripheral surface of the protective glass 23. Further, the unit main body 45 has an optical fiber 49 as an example of a light detection means for detecting detection light reflected in the protective glass 23 and emitted (leaked) from the outer peripheral surface of the protective glass 23. Is provided.

  With the above configuration, when contaminants such as spatters and fumes generated during laser processing by irradiating a workpiece (not shown) with the laser beam LB adhere to the protective glass 23, the detection light incident from the LED 47 is converted into the contaminants. Is irregularly reflected. This irregularly reflected light is detected by the optical fiber 49. Note that as the amount of spatter or the like attached to the protective glass 23 increases, the amount of light incident on the optical fiber 49 increases.

  Therefore, the detection light incident on the optical fiber 49 is converted into a voltage by a light receiving element (not shown). Then, by comparing the reference voltage set in advance with the converted voltage by means of voltage comparison means (not shown), it is possible to know the adhesion amount (contamination degree) such as sputtering on the protective glass 23.

  The irradiation means 43 includes a cylindrical illumination housing 51 attached to the lower surface of the unit main body 45. In the illumination housing 51, a cylindrical reflecting member 53 having a tapered reflecting surface 53F on the outer peripheral surface is provided. A plurality of LEDs 55 are provided around the reflecting surface 53F as illumination light sources for irradiating a laser processing position.

  Therefore, the light emitted from the LED 55 is reflected downward by the tapered reflecting surface 53F to illuminate the laser processing position. Therefore, the laser processing position can be easily imaged by the imaging means (not shown). As already understood, the irradiation means 43 is provided on the lower side of the glass holder unit 41 provided with the protective glass 23, and reflects the illumination light downward by the tapered reflecting surface 53F. Therefore, the protective glass 23 is not irradiated with light from the LED 55.

  Since the casing 31A provided below the irradiation means 43 has the same configuration as the conventional casing 31 described above, most of the spatter and fumes scattered from the laser processing position toward the protective glass 23 are transferred to the casing 31A. The air discharge port (not shown in FIG. 1) provided can be blown off to the outside.

  By the way, as already understood, the detection light for detecting the contamination of the protective glass 23 is incident on the protective glass 23 from the outer peripheral surface of the disk-shaped protective glass. As shown, the incident detection light DL is reflected by both the upper and lower inner surfaces of the protective glass 23 and also by the inner peripheral surface. Therefore, a large amount of detection light DL emitted from the LED 47 scans the inside of the protective glass 23. Therefore, one LED 47 is sufficient. When spatter or the like adheres to the lower surface of the protective glass 23, a large amount of the detection light DL is irregularly reflected by contaminants such as spatter, and the adhesion of contaminants such as spatter can be easily detected. is there. Since the amount of light is large, it is not affected by disturbance.

  As shown in FIG. 2B, when the protective glass 23 is irradiated with the detection light DL from above the protective glass 23, most of the detection light DL passes through the protective glass 23. The amount of the detection light DL reflected from the inner lower surface of the protective glass 23 and entering the protective glass 23 is very small. Therefore, as described in Patent Document 1, it is necessary to irradiate the entire surface of the protective glass 23, which requires many LEDs.

  By the way, when the detection light DL is incident from the outer peripheral surface of the protective glass 23, whether or not one LED 47 is sufficient, and a desirable positional relationship between the incident direction of the detection light by the LED 47 and the detection directing direction by the optical fiber 49. I investigated the relationship. That is, the detection level (light reception level) of the light amount when the LED 47 is arranged at the position A facing the optical fiber 49 and the detection light is incident is set to 1000. The detection level when the position of the LED 47 is changed every 22.5 ° and the detection light is incident is as shown in FIG.

  That is, the detection level was 1000 when the detection light was incident in a range of 45 ° in both directions with the facing position A in between (a range P1 of 90 ° as a whole). Therefore, when the LED 47 is arranged near the position A facing the optical fiber 49 and the detection light is incident on the protective glass 23, the detection light is directly incident on the optical fiber 49. Therefore, when the LED 49 is arranged in the range P1 where the detection light is directly incident on the optical fiber 49, the detection level is high, and in the configuration in which the detection light detects the reflected light irregularly reflected by sputtering or the like, the change in the light reception level is small. It is not desirable.

  The detection level when the detection light is incident in the 90 ° range P2 on both sides with the detection level (light reception level) in the range of 1000 is 300 or less and a low numerical value as shown in FIG. there were. That is, in the 90 ° range P2 on both sides, indirect light and scattered light, which are weak detection light incident from the LED 47 into the protective glass 23, are incident on the optical fiber 49. And in the structure which detects the reflected light irregularly reflected by the sputter | spatter etc., the change of a detection level is small and it is easy to receive to the influence of disturbances, such as external illumination, for example. Therefore, it is not desirable to arrange the LED 47 within the range P2 with respect to the arrangement position of the optical fiber 49.

  Next, when the LED 47 is arranged in a range of 45 ° to the both sides with the optical fiber 49 in between, that is, in a range P3 of 90 ° centering on the optical fiber 49, the light receiving level of the detection light incident on the optical fiber 49 Was as shown in FIG. That is, the light reception level was in the range of 400 to 600. When the LED 47 is arranged in this range P3 and enters the protective glass 23, the temporarily reflected light from the inner peripheral surface facing the LED 47 enters the optical fiber 49. When the LED 47 is arranged in this range P3, when the detection light is irregularly reflected by the spatter or the like attached to the protective glass 23 and enters the optical fiber 49, the change in the incident light is large and desirable.

  In the above-described configuration, the workpiece is laser processed by condensing the laser beam LB with the condensing lens provided in the laser processing head 1A and irradiating the workpiece with the laser beam LB. And most of the sputter and fume contaminants scattered from the laser processing position toward the protective glass 23 are discharged to the outside by the air curtain ejected by the air curtain forming means provided in the casing 31A. A part of the contaminant may adhere to the lower surface of the protective glass 23.

  In this case, the air curtain often adheres to the protective glass 23 while flowing downstream. Therefore, the contaminants tend to adhere to the downstream end side of the protective glass 23 when viewed in the flow direction of the air curtain. Therefore, it is desirable that the LED 47 is provided at an upstream position where the downstream end side of the protective glass 23 is irradiated.

  As understood from the above description, since the detection light is incident on the protective glass 23 from the outer peripheral surface by the LED 47, most of the detection light emitted from the LED 47 is incident on the protective glass 23. can do. Therefore, only one LED 47 for detection light may be used, and the configuration can be simplified.

  Further, when the detection light is incident from the outer peripheral surface of the protective glass 23, the incident detection light is reflected by the upper and lower inner surfaces and the inner peripheral surface of the protective glass 23. Therefore, the detection light incident on the protective glass 23 is irradiated over the entire protective glass 23 by reflection. In other words, the amount of detection light is kept large over the entire protective glass 23. In addition, the amount of detection light irregularly reflected by sputtering or the like can be kept large, the detection level can be increased, and the influence of disturbance can be suppressed.

  That is, the detection light is incident from the outer peripheral surface of the protective glass 23, and it is detected that the reflected light irregularly reflected by sputtering or the like is emitted from the outer peripheral surface of the protective glass 23 to detect adhesion of the sputter or the like. . Therefore, the detection of spatter and the like is more reliably performed as compared with the case where the detection light is emitted from the upper surface side or the lower surface side of the protective glass 23 and the reflected light irregularly reflected by the contaminant is emitted from the outer peripheral surface. Is something that can be done.

1A Laser processing head 23 Protective glass 41 Glass holder unit 43 Irradiation means 45 Unit main body 47 LED (detection light incident means)
49 Optical fiber (light detection means)
51 Lighting housing 55 LED (light source)

Claims (6)

  A method for detecting dirt on a protective glass provided in a laser processing head, wherein detection light is incident on the protective glass from the outer peripheral surface of the protective glass, is reflected by the peripheral surface of the protective glass, and adheres to the protective glass The protective glass is characterized in that the contamination of the protective glass is detected by detecting the amount of detection light diffused by the contaminated material and leaking from the outer peripheral surface by a light detection means provided on the peripheral surface of the protective glass. Dirt detection method.   2. The method for detecting dirt on a protective glass according to claim 1, wherein the detection light is incident on the protective glass within an angle of 45 ° or less between a detection directing direction of the light detection means and an incident direction of the detection light. A method for detecting dirt on a protective glass.   A laser processing head provided with a condensing lens and a protective glass for protecting the condensing lens, for making detection light for detecting dirt on the protective glass incident on the protective glass from the outer peripheral surface of the protective glass Detection light incident means and light detection means for detecting the amount of detection light reflected from the peripheral surface of the protective glass and leaked from the outer peripheral surface after being irregularly reflected by contaminants attached to the protective glass. A laser processing head characterized by that.   4. The laser processing head according to claim 3, wherein an angle formed by an incident direction of the detection light incident means and a detection directing direction of the light detection means is 45 ° or less.   5. The laser processing head according to claim 3, further comprising an air curtain forming means for blowing spatter and fumes generated during laser processing below the protective glass, and downstream of the air flow by the air curtain forming means. A laser processing head, wherein the detection light incident means is arranged at a position on the upstream side where the downstream end side of the protective glass corresponding to the side is irradiated.   6. The laser processing apparatus according to claim 3, wherein the protective glass is provided above an irradiation means for irradiating a laser processing position.

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