JP2022066081A - Laser welding head - Google Patents

Abstract

To provide a laser welding head that has a measurement system made changeable in a beam radiation position, shortened in a focal length and also shorten in movement time to the radiation position of the head, and accurately measuring a position of a radiation object united with the head, and further has an independent optical measurement system capable of measuring a molten pool shape, a temperature, luminance, and further a key hole depth incorporated thereto.SOLUTION: A laser welding head 1 which comprises a mechanism processing a workpiece W through laser radiation comprises: a trunk part 30 which is fixed to a laser welding robot moved freely in a predetermined movable region in a coordinate space having three orthogonal axes; a revolving unit 50 which is supported rotatably on a center of a parallel beam passing the trunk part; and a dichroic mirror 51 and a parabolic mirror 52 which are fixed to the revolving unit. The parallel beam passes through the dichroic mirror, and is reflected and converged by a concave surface of the parabolic mirror to become a processing beam B, which radiates the workpiece.SELECTED DRAWING: Figure 3

Description

The present invention relates to a laser processing apparatus, and more particularly to a compact and lightweight laser welding head.

In recent laser processing, laser welding using a solid-state laser has dramatically improved productivity by combining it with a robot. For example, in the invention disclosed in Patent Document 1, a laser welding robot provided with an irradiation head that intensively irradiates a laser beam from a light source is controlled by a computer program according to the type of a vehicle body.

In addition, the development of a technique for acquiring information in the vicinity of the machined portion by using an optical sensor for laser machining is also in progress. Patent Document 2 discloses an invention in which scattered light of a welded portion generated at the same time as laser processing is acquired by a photodiode and the presence or absence of a defect is confirmed.

The invention of further advancing the technology using the sensor, using a welded part detection sensor such as a camera in combination with the irradiation head, calculating the target welding position from the imaging information, and performing laser welding while correcting the position of the irradiation head is patented. It is disclosed in Document 3.

Japanese Unexamined Patent Publication No. 4-220187 Japanese Unexamined Patent Publication No. 11-058046 Japanese Unexamined Patent Publication No. 2002-192373

Since the general-purpose laser head has a fixed linear or right-angled refracted optical path and the focal optical system is designed to be long, there are multiple target irradiation positions, and the target plane has an angle and is scattered. In some cases, the equipment size is large, the head movement time and the positioning time are long, and the productivity may decrease.

There is also equipment that mounts a galvanometer mirror type optical system device that can quickly irradiate multiple points over a wide range on the robot, but it may be difficult to adopt due to the balance of cost, space, production efficiency, etc., so it is compact and lightweight and the amount of head movement is small. High productivity equipment may be desired.

Therefore, in the present invention, the head is configured with the minimum necessary dimensions, the beam irradiation position is variable, the focal length is shortened, the movement time of the head to the irradiation position is shortened, and the position of the irradiation target is accurately measured. It is an object of the present invention to provide a laser welding head in which a measurement system is integrated with a head and an independent optical measurement system capable of measuring the shape, temperature, brightness, and keyhole depth of a molten pool is incorporated.

The laser welding head of the present invention is intended to achieve the above-mentioned object, and the means of claim 1 is a laser welding head provided with a mechanism for processing a workpiece by laser irradiation, in which the laser welding head is orthogonal to the laser welding head. A trunk portion fixed to a laser welding robot that freely moves within a predetermined movable range of the three-axis coordinate space, and a swivel unit that is rotatably supported around the center of a parallel beam passing through the backbone portion. , A dichroic mirror and a parabolic mirror fixed to the swivel unit, the parallel beam is transmitted through the dichroic mirror, reflected and focused on the concave surface of the parabolic mirror, and becomes a processed beam. Is irradiated to the workpiece.

Further, according to the second aspect, the swivel unit includes a first illuminating device and a camera unit, and the first illuminating device directs the illuminating light to an arbitrary vicinity of the focal point of the processed beam of the workpiece. The camera unit irradiates linear light, and the camera unit senses the illuminated reflected light to acquire information on the state of the workpiece.

Further, in the means of claim 3, the camera unit includes a second lighting device, the second lighting device irradiates an workpiece with infrared light, and the camera unit emits infrared reflected light. It is characterized by sensing and acquiring information on the state of the workpiece.

Further, the means of claim 4 is that the camera unit includes a first camera and a second camera, and the first camera senses the illumination reflected light from a hole provided in the parabolic mirror. , And the second camera acquires the infrared reflected light reflected by the parabolic mirror and the dichroic mirror.

According to the configuration of claim 1, the laser welding head of the present invention is provided with a rotation mechanism of a swivel unit and a cooling unit in addition to the three-axis movement by the laser welding robot, so that the orientation of the machined surface of the workpiece is taken into consideration. It has the effect of enabling free beam irradiation. Further, since the drive system provided in the laser welding head is only the rotation mechanism of the swivel unit and the cooling unit, the size and weight can be reduced.

According to the second aspect, the position immediately before the molten pool of the work physical joint surface to be welded, the so-called seam, is accurately calculated from the image acquired by the camera unit of the laser welding head of the present invention. In addition, the position and rotation of the laser welding head so that the analysis calculation device compares the position information of the programmed straight line with the position information obtained from the linear shape of the image and irradiates the seam to be welded with an appropriate processing beam. Calculate the amount of rotation of the unit.

According to the third aspect, the camera unit of the laser welding head of the present invention obtains the temperature distribution of the workpiece and measures the temperature gradient of the designated points distributed around the keyhole in real time. Abnormalities can be detected from the pattern tendency.

According to the fourth aspect, the camera unit of the laser welding head of the present invention can achieve both control of operation of the laser welding head and detection of abnormality in a compact configuration.

It is a perspective view of the whole of the laser welding head of this invention. It is a front view of the whole of the laser welding head of this invention. It is sectional drawing of the laser welding head of this invention. It is a perspective view of the whole of the laser welding head which shows the state which the swivel unit and the cooling unit rotated 90 degrees from the state of FIG. It is an enlarged perspective view and schematic cross-sectional view of a work piece. It is a schematic diagram of the image acquired by the second camera.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is an overall perspective view of the laser welding head 1 of the present invention. Further, FIG. 2 is an overall front view of the laser welding head 1 of the present invention. The laser welding head 1 is provided with a mechanism for processing the workpiece W by laser irradiation, and has an optical connector 10 to which an optical fiber cable for transmitting a laser beam is transmitted from a laser oscillation unit and a laser beam that has passed through the optical connector 10. 20 is provided with a collimator unit 20 that converts the light into a parallel beam.

The collimator unit 20 is connected to a core unit 30 fixed to the laser welding robot. The laser welding robot freely moves the fixed laser welding head 1 within a predetermined movable range in the coordinate space of three orthogonal axes. The trunk portion 30 includes a first flange 31 for connecting the collimator portion 20 and a second flange 32 for fixing to the laser welding robot. The first flange 31 is provided with a first screw hole group 33 for screwing to the third flange 21 of the collimator portion 20 in the vicinity of the edge portion of the first flange 31, and the second flange 32 is a laser. A second screw hole group 34 for screwing to the welding robot is provided near the edge of the second flange 32. A third screw hole group 22 is provided at a position corresponding to the first screw hole group 33 in the vicinity of the edge portion of the third flange 21.

FIG. 3 is a cross-sectional view taken along the line III-III of the laser welding head 1. The inside of the trunk portion 30 is processed into a hollow cylindrical shape, and a bearing mechanism is provided on the inner wall. The bearing mechanism of this embodiment adopts the bearing 35. The cooling unit 40 supported by the bearing mechanism receives power from the motor 36 installed in the trunk portion 30 and rotates around the center of the optical path of the parallel beam. The motor 36 has a rotation position camera function, and the rotation position information of the motor 36 is transferred wirelessly or by wire to an analysis calculation device (not shown) and used for controlling the rotation direction of the rotation unit 50 described later.

Further, the inside of the cooling unit 40 is processed into a hollow cylindrical shape through which a parallel beam passes. The cooling unit 40 is provided with cooling water connectors 41 at two locations on the outer peripheral side surface. The cooling water flows in and out of the cooling water connector 41.

A swivel unit 50 is provided on the front side of the parallel beam optical path of the cooling unit 40. The swivel unit 50 is rotatably supported around the center of the parallel beam passing through the trunk portion 30 together with the cooling unit 40. FIG. 4 shows a state in which the swivel unit 50 and the cooling unit 40 are rotated 90 degrees from the state of FIG. The laser welding head 1 of this embodiment is provided with a rotation mechanism of the swivel unit 50 and the cooling unit 40 in addition to the three-axis movement by the laser welding robot, so that the orientation of the machined surface of the workpiece W can be freely considered. Enables beam irradiation.

The swivel unit 50 has a square cylindrical structure, and mirrors are fixed to the vicinity of the end portion on the cooling unit 40 side and the intermediate portion inside the swivel unit 50, respectively. A cooling water channel (not shown) is provided inside the swivel unit 50. Cooling water flowing in and out of the cooling unit 40 circulates in the cooling water channel and is used for cooling the entire swirling unit 50 including the mirror. The mirror fixed in the vicinity of the intermediate portion on the cooling unit 40 side is the dichroic mirror 51, and the mirror fixed to the end portion is the parabolic mirror 52.

The dichroic mirror 51 of this embodiment transmits a parallel beam. The parallel beam transmitted through the dichroic mirror 51 is reflected and focused on the concave surface of the parabolic mirror 52, becomes a processed beam B, and is irradiated from the beam opening 53 toward the workpiece W. A protective glass 54 is detachably attached to the beam opening 53. The protective glass 54 prevents damage to the parabolic mirror 52 due to adhesion of scattered foreign matter such as fume and spatter due to melting of the workpiece W to the parabolic mirror 52. The protective glass 54 transmits the processed beam B and the scattered light of the processed beam B. If the protective glass 54 becomes dirty, replace it immediately.

The laser welding head 1 of the present invention controls the rotation of the laser welding robot and the swivel unit 50 so that the focus of the machining beam B focused by the parabolic mirror 52 is aligned with the machining position of the workpiece W, and the workpiece is covered. The work piece W is processed. A reflective coating is applied to the concave surface of the parabolic mirror 52, and a water channel for reducing the energy absorption of the parabolic mirror 52 and effectively discharging the generated heat is formed inside the mirror.

A first lighting device 55 is attached to the tip of the swivel unit 50. The first illuminating device 55 irradiates the illumination light L from the illumination opening 56 to an arbitrary vicinity of the focal point of the processing beam B of the workpiece W and reflects the illumination light L. As a specific example, the illumination light L is a blue laser in the vicinity of 450 nm, and irradiates the seam of the workpiece W linearly with a width of 10 μm and a length of about 10 mm from a position inclined at 30 degrees. The illumination reflected light is incident on the inside of the swivel unit 50 from the beam opening 53.

The swivel unit 50 has four sides parallel to the traveling direction of the parallel beam. A camera unit 60 is provided on the outside of the upper side surface 50b of the turning unit facing the lower side surface 50a of the turning unit provided with the beam opening 53. The camera unit 60 senses the illumination reflected light incident on the inside of the swivel unit 50 and acquires information on the state of the workpiece W.

Here, the parabolic mirror 52 is provided with a perforation 57 that penetrates in the incident direction of the illumination reflected light, that is, in the direction from the lower side surface 50a of the swivel unit to the upper side surface 50b of the swivel unit. In this embodiment, a first camera 61 that senses illuminated reflected light is installed at a position directly above the perforation 57 in the camera unit 60, and the first camera 61 passes through the perforation 57 and is near the processing portion of the workpiece W. It is configured to acquire the image of. The perforation 57 has a large diameter on the side of the first camera 61 and a small diameter on the side of the beam opening 53, expanding the field of view of the first camera 61. The position of the perforation 57 is preferably the central portion or the vicinity of the central portion of the parabolic mirror 52. The first camera 61 of this embodiment is a CMOS camera.

FIG. 5 is an enlarged perspective view and a schematic cross-sectional view of the workpiece W. FIG. 5A is a perspective view of the workpiece W, and FIG. 5B is an image diagram of a cross section of the workpiece W that can be acquired by the first camera 61. The first camera 61 acquires an image of the vicinity of the processed portion of the workpiece. Specifically, the illumination light L radiated linearly from the first illumination device 55 at an angle recognizes the unbalanced cross-sectional state of the seam W1 due to a processing error or a slight step as an image to the first camera 61. Let me. By enlarging the narrow groove W2 of the seam W1 with an optical system, the position of the bottom of the V-shaped groove W2 is determined. The acquired image is transferred to an analysis calculation device (not shown) wirelessly or by wire, and the position immediately before the molten pool of the work physical joint surface to be welded, the so-called seam W1, is accurately calculated from the image data. The analysis calculation device compares the position information of the programmed straight line with the position information obtained from the linear shape of the image, and the position of the laser welding head 1 and the position of the laser welding head 1 so as to irradiate the seam W1 to be welded with an appropriate processing beam B. The amount of rotation of the swivel unit 50 is calculated.

In this embodiment, the camera unit 60 is provided with the second camera 62. A second lighting device 63 is installed at the tip of the second camera 62, and the wavelength of the lighting is infrared light in the vicinity of 800 nm. The infrared light emitted from the second illuminating device 63 is reflected by the dichroic mirror 51 and the parabolic mirror 52, is irradiated to the workpiece W from the beam opening 53, and becomes the infrared reflected light, which is the second light. It is detected by the camera 62. The scattered light of the processed beam B mixed with the infrared reflected light passes through the dichroic mirror 51. The second camera 62 of this embodiment can be replaced with a purpose-specific camera having a measurement function capable of acquiring the temperature and brightness distribution of the molten pool and its vicinity, the depth of the keyhole, and the like, and is to be processed. Acquires information about the state of the object W. The acquired information is transferred wirelessly or by wire to an analysis calculation device (not shown) and used for temperature and luminance distribution measurement and the like.

FIG. 6 is a schematic diagram of an image acquired by the second camera 62. In FIG. 6, the temperature distribution of the workpiece W is acquired as contour lines W3. From the image, the seam W1, the keyhole W4, the molten pool W5 and the molten bead W6 can be discriminated. Welding proceeds in the direction of the arrow in FIG. By measuring the temperature gradient of the designated points distributed around the keyhole W4 in real time, the abnormality can be detected from the obtained pattern tendency.

The laser welding head 1 of the present invention can correspond to various laser oscillators by appropriately selecting an optical connector 10, a collimator unit 20, a dichroic mirror 51, a parabolic mirror 52, and a camera unit 60. For example, a YAG laser, a fiber laser, a disk laser, and a semiconductor laser are suitable.

1 ... Laser welding head.
10 ... Optical connector.
20 ... Collimator section, 21 ... Third flange, 22 ... Third screw hole group.
30 ... backbone, 31 ... first flange, 32 ... second flange, 33 ... first screw hole group, 34 ... second screw hole group, 35 ... bearing, 36 ... motor.
40 ... Cooling unit, 41 ... Cooling water connector.
50 ... swivel unit, 50a ... swivel unit lower side, 50b ... swivel unit upper side, 51 ... dichroic mirror, 52 ... parabolic mirror, 53 ... beam opening, 54 ... protective glass, 55 ... first lighting device, 56 ... Illumination opening, 57 ... perforation.
60 ... camera unit, 61 ... first camera, 62 ... second camera, 63 ... second lighting device.
W ... workpiece, W1 ... seam, W2 ... groove, W3 ... contour lines, W4 ... keyhole, W5 ... molten pond, W6 ... molten bead.
B ... Processed beam L ... Illumination light

Claims (4)

In a laser welding head equipped with a mechanism for processing a workpiece by laser irradiation,
A core portion fixed to a laser welding robot that freely moves the laser welding head within a predetermined movable range in coordinate spaces of three orthogonal axes, and a trunk portion.
A swivel unit that is rotatably supported around the center of a parallel beam that passes through the backbone, and
A dichroic mirror and a parabolic mirror fixed to the swivel unit are provided.
The laser welding head is characterized in that the parallel beam passes through the dichroic mirror, is reflected and condensed on the concave surface of the parabolic mirror to become a processed beam, and the processed beam is applied to the workpiece. The swivel unit includes a first lighting device and a camera unit.
The first illuminating device irradiates the illumination light linearly in an arbitrary vicinity of the focal point of the processing beam of the workpiece, and the camera unit senses the illumination reflected light to acquire information on the state of the workpiece. The laser welding head according to claim 1, wherein the laser welding head is made. The camera unit includes a second lighting device.
The second illuminating device irradiates an workpiece with infrared light, and the camera unit senses the infrared reflected light to acquire information on the state of the workpiece. 2. The laser welding head according to 2. The camera unit includes a first camera and a second camera.
The first camera senses the illumination reflected light from the perforation provided in the parabolic mirror, and
The laser welding head according to claim 3, wherein the second camera acquires the infrared reflected light reflected by the parabolic mirror and the dichroic mirror.

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