JP3726774B2 - Laser welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a laser welding apparatus, and in particular, welding is performed while the filler wire as a welding material is aligned with the focal position of a laser beam irradiated on an object to be welded and the filler wire is sequentially fed out. The present invention relates to a laser welding apparatus.
[0002]
[Prior art]
As a technique related to this type of conventional laser welding, for example, as described in Japanese Patent Application Laid-Open No. 2001-17941, a laser head portion that functions as a laser optical system and a filler wire that is a welding material are guided. While supporting the wire supply unit (wire nozzle unit) to be sequentially fed to the wrist unit of the industrial robot that will function as a welding mother machine, the laser head unit and the wire supply unit are set in advance. It is known that welding is performed by moving at a predetermined speed using the degree of freedom of the robot itself along the welding locus data.
[0003]
In this case, as described in Japanese Patent Application Laid-Open No. 6-71470, the edge of the workpiece is an actual welding locus by a predetermined sensor arranged on the front side in the welding direction with respect to the wire supply portion. The laser head unit and the wire supply unit are respectively moved so as to be detected as the power position and to follow the welding locus.
[0004]
[Problems to be solved by the invention]
In such conventional laser welding technology, the entire processing head including the laser head and the wire supply unit is integrated as one unit, for example, supported on the wrist unit at the tip of the robot arm and then moved using the movement of the robot itself. Therefore, the volume of the movable part at the most advanced part of the robot arm becomes large, and problems such as interference with incidental devices that are arranged in proximity are likely to occur.
[0005]
In addition, the laser beam irradiation position, which is the most important for the welding function, and the distance from the tip position of the filler wire to the drive fulcrum are inevitably large, so the movement at the time of minute displacement is particularly slow. The irradiation position of the laser beam and the tip position of the filler wire are likely to vary due to the influence of vibration and rattling other than the movable part, and as a result, improvement in welding quality cannot be expected.
[0006]
The present invention has been made paying attention to such conventional problems, and in particular, the movable part at the most advanced part of the welding mother machine such as an industrial robot can be made as small as possible to enable high-speed and high-precision welding work. A laser welding apparatus is provided .
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a laser head unit capable of irradiating a workpiece with a laser beam and displacing a focal position of the laser beam on the workpiece along a predetermined locus; While guiding the filler wire that is the welding material, the wire is sequentially supplied to the focal position of the laser beam, and the focal position of the laser beam is maintained while maintaining the relative positional relationship between the focal position of the laser beam and the tip position of the filler wire. At least one of a wire supply section that is displaced in conjunction with the displacement of the laser beam, a support that supports both the laser head section and the wire supply section, and a laser head position to displace the focal position of the laser beam along a predetermined locus. and laser light irradiation position changing means for driving the parts, is interposed between the support and the wire feed unit, the when the wire supply part to the displacement of the focus position of the laser beam is interlocked Characterized by comprising a floating mechanism which allows relative positional relationship relative displacement between the support and the wire feed unit while maintaining the focal position and the filler wire tip position of the laser light, a.
[0008]
In this case, the welding mother machine is, for example, an industrial robot (welding robot itself).
[0010]
According to the first aspect of the present invention, it is desirable to irradiate the laser beam to a position offset from the axis of the laser head part itself from the laser head part as described in the second aspect. In addition to the method using the refracting means as described in claim 3, the optical axis of the laser beam itself may be inclined at a predetermined angle with respect to the axis of the laser head portion itself.
[0012]
Furthermore, as described in claim 3 , the laser beam irradiation position changing means is provided in the laser head part so as to be displaceable, and directs the laser beam to a position offset from the axis of the laser head part itself with respect to the workpiece. It is desirable to include a refracting means for refracting the laser light to be irradiated and a driving means for displacing the refracting means. More preferably, as described in claim 4, the refracting means is rotatably provided in the laser head portion, and the focal position of the laser beam on the workpiece to be welded according to the rotational displacement of the refracting means by the driving means. Is rotated and displaced on a circular trajectory centered on the axis of the laser head, and the wire supply unit is rotationally displaced so that the tip of the filler wire is rotationally displaced on the same circular trajectory. .
[0013]
In particular, for further downsizing of the entire apparatus, as described in claim 5 , the refracting means and the wire supply section are rotationally driven by the common driving means with the same rotation ratio. Is desirable.
[0014]
Also, floating freedom by floating mechanism according to claim 1, as claimed in claim 6, sufficient if configured as flexibility in a plane perpendicular to the axis of the laser head.
[0015]
Thus, in the invention the mounting serial to these claims 1-6, when the refracting means is rotationally displaced by the driving means constitute the laser light irradiation position changing means, the focal position of the laser beam in the welding Butsujo Since the rotational amount of the offset from the axis of the laser head itself is rotationally displaced on a circular locus having a radius, the continuous movement in the welding direction depends on the movement of the welding mother machine such as a welding robot. However, for example, in the direction orthogonal to the welding direction, it is possible to change the irradiation position of the laser beam with the rotational displacement on the circular locus.
[0016]
On the other hand, when the focal position of the laser beam on the workpiece is displaced, the relative positional relationship between the focal position and the tip of the filler wire still needs to be maintained as before. Therefore, when the irradiation position of the laser beam is changed with the rotational displacement on the circular locus as described above, the relative position relationship between the focal position of the laser beam and the tip of the filler wire is maintained in conjunction with that, and on the same circular locus. The wire supply unit rotates with the rotational displacement. In this case, as described in claim 5, if the refracting means and the wire supply unit are rotationally driven by the common driving means with the same rotation ratio, the floating mechanism of the floating mechanism according to claim 6 is used. The refraction means and the wire supply unit are completely synchronized with a degree of freedom, and the wire supply unit automatically follows the movement of the focal position of the laser beam.
[0017]
According to a seventh aspect of the invention, on the premise of any one of the first to sixth aspects , at least a laser beam irradiation position change is made to move the laser head unit and the wire supply unit along preset ideal welding trajectory data. Control means for controlling the means, detection means for detecting the edge of the workpiece to be welded as a detection target on the front side in the welding direction from the actual welding position by the wire supply unit, and detection by the detection means Based on the output and preset ideal welding trajectory data, the difference between the two at the corresponding part is calculated as correction amount data, and this correction amount data is used as the displacement amount of the focal position of the laser beam by the laser beam irradiation position changing means. And an arithmetic means for giving to the control means as a command.
[0019]
Therefore, according to the seventh aspect of the present invention, even if the edge position of the workpiece to be the actual welding locus is deviated from the ideal welding locus position taught in advance, The focal position of the laser beam is automatically corrected while keeping the relative positional relationship with the tip of the filler wire so as to follow the edge position of the weldment.
[0020]
【The invention's effect】
According to the first and second aspects of the invention, unlike the method in which the entire processing head unit including the laser head unit and the wire supply unit is driven as a single unit, only the minimum necessary portion is driven by the minimum required amount. Since it is a system, the movable part at the tip can be reduced in size, the irradiation position of the laser beam can be changed at high speed, and it is less susceptible to the vibration and rattling of the non-movable part. The laser beam irradiation position accuracy and filler wire supply position accuracy are improved, welding accuracy is greatly improved , and a floating mechanism is interposed between the support and the wire supply unit, so the focus of the laser beam is increased. There is an effect that the wire supply unit can be linked mechanically and smoothly to the displacement of the position.
[0022]
According to the third and fourth aspects of the invention, the refracting means provided in the laser head section is driven by the driving means, or the refracting means provided rotatably in the laser head section is used as the driving means. Therefore, there is an advantage that the movable part can be further reduced in size.
[0023]
According to the fifth aspect of the invention, since the refracting means and the wire supply unit are rotationally driven by the common driving means, the driving means and the drive control system can be further reduced in size and simplified, and the refraction is also performed. The synchronization accuracy between the means and the wire supply unit can be increased.
[0024]
According to the sixth aspect of the present invention, since the degree of freedom of floating by the floating mechanism is set as the degree of freedom in a plane orthogonal to the axis of the laser head, even if the wire supply section is displaced, the wire supply The orientation of the part itself and the filler wire supply orientation do not change at all, and there is an advantage that the filler wire can always be stably supplied to the laser beam focal position from a certain direction.
[0025]
According to the seventh aspect of the present invention, since the laser beam irradiation position is changed so as to conform to the actual edge position shape of the workpiece, so-called copying control is performed. Variations in shape are less likely to affect welding quality and can contribute to improving and stabilizing welding quality.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 to 3 are views showing a preferred first embodiment of a laser welding apparatus according to the present invention, in particular FIG. 1 is an explanatory side view thereof, FIG. 2 is an enlarged plan view at a laser beam irradiation position, 3A and 3B are a side explanatory view and a plane explanatory view when the structure of FIG. 1 is schematically shown.
[0027]
As shown in FIG. 1, the laser welding apparatus has a laser head portion 1 with a built-in laser optical system and a filler wire 2 that is a welding material, and its tip always coincides with a laser beam irradiation position (focal position) P. As shown in FIG. 3, the laser head unit 1 and the wire supply unit 3 are bifurcated brackets as a support. 4 is supported by a wrist portion R of a welding robot (industrial robot) (not shown) that functions as a welding mother machine.
[0028]
In the cylindrical head body 5 in the laser head unit 1, a wedge plate 6, a collimation lens 7 and a focusing lens 8 are arranged as an optical system in order from the upper side, and the wedge plate 6 is shown in FIG. As shown in FIG. 2, the focal position P of the laser beam L is offset by a predetermined amount R1 with respect to the center Q of the head body 5 (the emission optical axis before the laser beam L passes through the wedge plate 6) Q according to the inclination of itself. It has a function. Accordingly, the laser light L output from a laser oscillator (not shown) passes through the wedge plate 6, the collimation lens 7, and the focusing lens 8, and then is a distance R1 from the emission optical axis Q at the focal position P on the workpiece W. Only the offset position is irradiated.
[0029]
A laser side rotating body 9 whose center is coincident with the center Q of the head body 5 is provided in the head body 5, and a wedge plate 6 is attached to the laser side rotating body 9. As a result, the wedge plate 6 rotates together with the laser-side rotator 9 so that the focal position P of the laser light L moves on the circumference M of the radius R1 with the emission optical axis Q as the center.
[0030]
A laser-side driven gear 10 is integrally formed on the outer periphery of the laser-side rotating body 9. On the other hand, in the gear box 11 adjacent to the laser head portion 1, both the driven gears 10 and 12 in addition to the wire-side driven gear 12 are provided. An intermeshing small-diameter drive gear (intermediate gear) 13 is provided, and the drive gear 13 is rotationally driven by a servo motor 14 as drive means. Here, since the laser-side driven gear 10 and the wire-side driven gear 12 have the same gear specifications including the pitch circle diameter and the number of teeth, the laser-side driven gear 10 and the wire-side driven gear 12 have a 1: 1 speed. They rotate synchronously in the same direction with a ratio. Therefore, when the servo motor 14 is started, the wedge plate 6 is rotationally driven together with the laser side rotator 9, and the servo motor 14, the drive gear 13, the laser side driven gear 10, the laser side rotator 9, and the wedge plate 6 are driven. Thus, the laser beam irradiation position changing means 15 is configured.
[0031]
The wire-side driven gear 12 is provided with another wire-side rotating body 16 integrally therewith, and a ball joint 17 is provided at the lower end of the wire-side rotating body 16 at a position offset by a distance R2 from the center of rotation. It has been. This offset amount R2 is set so as to be equal to the rotation radius R1 of the focal position P around the emission optical axis Q described above.
[0032]
On the other hand, the wire supply unit 3 that guides the filler wire 2 is fixedly supported by a horizontal stay 18 with a downwardly inclined posture, and the tip of the stay 18 is supported by the wire side rotating body 16 via a ball joint 17. In addition, the stay 18 itself is slidably inserted and supported by the slider joint 19. The servo motor 14 and the drive gear 13 rotate the laser side rotating body 9 via the laser side driven gear 10 and simultaneously rotate the wire side rotating body 16 via the wire side driven gear 12. Therefore, the servo motor 14 and the drive gear 13 also serve as driving means for rotating and displacing the wire supply unit 3 as will be described later.
[0033]
As shown in FIG. 3, the slider joint 19 is a combination of a pair of joint sleeves 20, 21 so that their axes are orthogonal to each other, and one joint sleeve 20 is attached to the support bar 22 on the bracket 4 side. The other joint sleeve 21 is inserted and supported by the stay 18 so as to be slidable. The stay 18, slider joint 19 and support bar 22 together with the ball joint 17 constitute a floating mechanism 23 that supports the wire supply unit 3 so that it can float. The wire supply unit 3 includes the ball joint 17 and the floating mechanism 23. It is supported so as to be slidable in two orthogonal directions in a horizontal plane orthogonal to the rotation center of the wire-side rotating body 16 with a degree of freedom.
[0034]
Therefore, when the wire side rotating body 16 is rotationally driven, the wire supply unit 3 is rotationally displaced on the circumference having a radius R2 from the center of the wire side rotating body 16 to the ball joint 17 in the horizontal plane. However, since the posture of the wire supply unit 3 itself is restrained by the stay 18 and the slider joint 19 so that the posture of the wire supply unit 3 itself does not change, the movement at the tip of the filler wire 2 guided to the wire supply unit 3 is The movement is set on the same circumference as the circumference M of the radius R1 drawn by the focal position P while the tip and the focal position P of the laser beam L coincide with each other.
[0035]
According to this embodiment configured as described above, as shown in FIG. 2, the tip position of the filler wire 2 fed out while being guided by the wire supply unit 3 is positioned on the extension axis of the wire supply unit 3 itself. In addition, the rotation of the rotating bodies 9 and 16 on the laser side and the wire side is performed so that the focal position P and the tip position of the filler wire 2 coincide with each other on the circumference M drawn by the focal position P of the laser beam L. Assume that the start positions are adjusted in advance. Note that the inclination angle α in FIG. 2 is always constant.
[0036]
When the servo motor 14 is started in this state, the focal position P on the workpiece W is rotationally displaced along the circumference M of the radius R1 with the rotation of the wedge plate 6 supported by the laser side rotating body 9. The wire supply unit 3 supported by the wire-side rotating body 16 in purely mechanical synchronization with this movement is also rotationally displaced on the circumference of the same radius R2 (R1 = R2). If the focal position P and the tip position of the filler wire 2 are matched in advance on the weld W, and the filler wire 2 is sent out in synchronization therewith, the focal position P of the laser light L and the filler wire 2 The tip position is always rotationally displaced along the circumference M of the radius R1 while the position remains the same.
[0037]
Therefore, while the main welding feed is given by the welding robot, the focal position P of the laser beam L and the tip position of the filler wire 2 whose positions coincide with each other in advance as described above are synchronized with each other as described above. By moving along the circumference M, laser welding along an arbitrary welding trajectory can be performed.
[0038]
4A and 4B show a second embodiment of the present invention. However, the same reference numerals are given to the parts common to the first embodiment.
[0039]
In the second embodiment, apart from the wire-side rotating body 16 that is forcibly driven to rotate by the servo motor 14 shown in FIG. 1, the wire-side rotating body 16 and the shaft are parallel, have the same diameter, and are driven. An auxiliary rotating body 26 capable of rotating is added. A ball joint 27 is provided on the lower surface of the auxiliary rotator 26 at a position away from the axis of the auxiliary rotator 26, and the upper side of the wire supply portion 33 in a downward inclined posture is interposed between the auxiliary rotator 26 and the ball joint 27. It is supported by. The distance between the center of the auxiliary rotating body 26 and the ball joint 27 is set to the same size as the distance between the center of the wire side rotating body 16 and the ball joint 17, and the center of the auxiliary rotating body 26 and the ball joint 27. The rotational phase positions of both rotary bodies 16 and 26 are set so that the line connecting the two and the ball joint 17 is parallel to the line connecting the center of the wire side rotary body 16 and the shorter one as a result. A four-joint parallel link mechanism having a radius R3 of the length of the arm is formed. The radius R3 is set to be equal to the radius R1 of the circumference M drawn by the focal position of the laser light L. Accordingly, the ball joints 17 and 27 and the auxiliary rotating body 26 forming the four-bar parallel link mechanism form a floating mechanism 30 that supports the wire supply unit 33 so as to be able to float.
[0040]
Therefore, according to the second embodiment, the wire-side rotating body 16 and the auxiliary rotating body 26 are rotated, so that the wire supply unit 33 is restrained by the four-bar parallel link mechanism and the radius R1 (= R3). Thus, the same function as that of the first embodiment is exhibited.
[0041]
FIGS. 5 and 6 are views showing a third embodiment of the present invention, and the same reference numerals are given to the parts common to the first embodiment shown in FIG.
[0042]
As shown in FIG. 5, the focal position P of the laser light L on the workpiece W and the tip position of the filler wire 2 fed out from the wire supply unit 3 are matched in advance, and preset ideal trajectory data. The control circuit 40 gives a forward / reverse drive command to the servo motor 14 to move the laser head unit 1 and the wire supply unit 3 along the locus F based on (teaching data taught in advance). The tip end position of the filler wire 2 is rotationally displaced on the circumference M of the radius R1 while being in agreement with each other.
[0043]
On the other hand, in the present embodiment, a non-contact type edge sensor 41 is provided adjacent to the wire supply unit 3 as a detection means and directs in the direction of the workpiece W. The edge sensor 41 includes the laser head unit 1 and It is supported by the same support body with the wire supply part 3. The edge sensor 41 irradiates the laser slit light S in such a manner as to be orthogonal to the welding feed direction in front of the welding direction of the workpiece W from the actual welding position by the welding torch 3. The edge position of the welded portion W is continuously detected by capturing the reflected light of the above. Here, for example, since lap joint welding is assumed, as shown in FIG. 6, the edge (edge part) E of one workpiece W1 on the upper side is detected, and the position is set as an actual welding locus. In the case of butt joint welding, a butt portion or a gap between workpieces can be detected in the same manner. In short, it is only necessary to be able to detect the edge position of the workpiece W (W1) to be welded. Instead of the edge sensor 41 integrated with the light projecting / receiving unit as described above, for example, the reflected light of the laser slit light S is CCD or the like. A solid-state image pickup device may be used.
[0044]
As shown in FIG. 6 in addition to FIG. 5, the detection position by the edge sensor 41 always precedes the actual welding position by the wire supply unit 3 by the offset amount S1, and the detection output of the edge sensor 41 is the arithmetic circuit 42. And the difference between the current actual welding position (the focal position P of the laser beam L and the tip position of the filler wire 2 that coincide with each other) is calculated as the correction amount data D. However, here, it is assumed that the trajectory F based on the ideal trajectory data matches the current actual welding position, and the above arithmetic processing is performed. The correction amount data D is sequentially input to the control circuit 40, converted into a drive command for the servo motor 14, that is, a laser beam L or a rotational displacement amount command for the wire supply unit 3, and then the offset amount S1. The servo motor 14 is given with a corresponding time delay.
[0045]
In the example of FIG. 6, when it is assumed that welding has progressed from the state of (A) in the figure by the offset amount S <b> 1 and the state of FIG. In response, the laser beam L and the wire supply unit 3 are driven to rotate by the servo motor 14, so that the focal position P of the laser beam L and the welding position, which is the tip position of the filler wire 2, move by a distance D. Become. Accordingly, the focal position P of the laser beam L and the tip position of the filler wire 2 are always applied to the edge E of the workpiece W (W1) regardless of changes in the shape and position of the edge E of the workpiece W (W1). Can be matched.
[Brief description of the drawings]
FIG. 1 is an explanatory side view showing a first embodiment of a laser welding apparatus according to the present invention.
FIG. 2 is an explanatory plan view of the vicinity of a laser beam focal position in FIG. 1;
3A is an explanatory side view schematically showing the structure of FIG. 1, and FIG. 3B is an explanatory plan view of FIG.
FIGS. 4A and 4B are diagrams showing a second embodiment of the laser welding apparatus according to the present invention, in which FIG. 4A is a side view thereof, and FIG. 4B is a plan view of FIG.
FIG. 5 is an explanatory side view of an essential part showing a third embodiment of a laser welding apparatus according to the present invention.
6A and 6B are plan explanatory views showing the operation of the laser welding apparatus of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser head part 2 ... Filler wire (welding material)
3 ... Wire supply part 4 ... Bracket (support)
6 ... Wedge plate (refractive means)
DESCRIPTION OF SYMBOLS 9 ... Laser side rotary body 10 ... Laser side driven gear 12 ... Wire side driven gear 13 ... Drive gear 14 ... Servo motor (drive means)
DESCRIPTION OF SYMBOLS 15 ... Laser beam irradiation position change means 16 ... Wire side rotating body 17 ... Ball joint 19 ... Slider joint 23 ... Floating mechanism 26 ... Auxiliary rotating body 27 ... Ball joint 30 ... Floating mechanism 40 ... Control circuit 41 ... Edge sensor (detection means) )
42 ... arithmetic circuit D ... correction amount data E ... edge F of workpiece to be welded ... locus L based on ideal locus data ... laser beam P ... focus position W, W1 of laser beam ... workpiece

Claims (7)

A laser head unit capable of irradiating the workpiece with laser light and displacing the focal position of the laser beam on the workpiece along a predetermined locus;
While guiding the filler wire that is the welding material, the wire is sequentially supplied to the focal position of the laser beam, and the focal position of the laser beam is maintained while maintaining the relative positional relationship between the focal position of the laser beam and the tip position of the filler wire. A wire supply section that is displaced in conjunction with the displacement of
A support for supporting both the laser head unit and the wire supply unit;
Laser light irradiation position changing means for driving at least a part of the laser head part to displace the focal position of the laser light along a predetermined locus;
It is interposed between the support and the wire supply unit, and when the wire supply unit is interlocked with the displacement of the focal position of the laser beam, the relative positional relationship between the focal position of the laser beam and the tip position of the filler wire is maintained. A floating mechanism that allows relative displacement between the support and the wire supply unit,
A laser welding apparatus comprising:   2. The laser welding apparatus according to claim 1, wherein the laser head unit irradiates the workpiece with laser light at a position offset from the axis of the laser head unit itself. The laser beam irradiation position changing means is
A refracting means provided in the laser head portion so as to be displaceable, and refracting the laser beam so as to irradiate the laser beam to a position offset from the axis of the laser head portion itself with respect to the workpiece;
Drive means for displacing the refraction means;
The laser welding apparatus according to claim 1, further comprising: The refracting means is rotatably provided in the laser head part,
In accordance with the rotational displacement of the refracting means by the driving means, the focal position of the laser beam on the workpiece is rotationally displaced on a circular locus with the axis of the laser head as the rotation center,
Serial mounting laser welding apparatus in claim 3, wherein a tip of the filler wire in conjunction therewith and is adapted to rotate displacing the wire supply part to rotational displacement in the same circular trajectory on. Refracting means and the wire supply and a common drive means that are adapted to be rotationally driven with a same rotation ratio by serial mounting laser welding apparatus to claim 4, characterized in. 2. The laser welding apparatus according to claim 1, wherein the degree of freedom of floating by the floating mechanism is set as a degree of freedom in a plane perpendicular to the axis of the laser head portion. Control means for controlling at least the laser light irradiation position changing means to move the laser head part and the wire supply part along the preset ideal welding trajectory data;
Detection means for detecting the edge of the workpiece to be welded with the welding direction front side from the actual welding position by the wire supply unit as a detection target;
Based on the detection output from the detection means and preset ideal welding trajectory data, the difference between the two is calculated as correction amount data, and this correction amount data is used as the focal point of the laser light by the laser light irradiation position changing means. Arithmetic means for giving to the control means as a positional displacement command;
The laser welding apparatus according to claim 1, comprising:

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