JP2902550B2 - Laser processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam machine,
Particularly, the present invention relates to a laser processing machine capable of performing high-quality welding.

[0002]

2. Description of the Related Art By condensing a laser beam on a small spot and irradiating it on a processing target such as a metal, processing such as cutting and welding can be performed.

By irradiating a single laser beam spot onto a processing object and relatively scanning the processing object and the laser beam spot, processing of a desired shape can be performed. Heating may cause adverse effects such as distortion.

As a countermeasure against such a phenomenon, a method of defocusing a laser beam and expanding the beam diameter, and a method of operating a laser beam spot while rotating the laser beam spot by a trepanning head or the like are known.

However, when performing laser lap welding, laser butt welding, or the like, it may be desirable to perform auxiliary heating before or after the main welding with a laser beam. In order to perform such auxiliary heating, if another laser is prepared and a plurality of laser beams are irradiated, improvement in welding quality and stability can be realized, but the configuration of the laser processing machine becomes complicated. I will.

In butt welding of different materials having different heat capacities and melting points, the energy suitable for each material is different, and in order to perform high quality welding, a laser beam energy suitable for each different material is applied. It is desired.

[0007] In the case of performing such butt welding of different kinds of materials with a single laser beam, a technique for decentering the butt position and the center position of the laser beam is used. In this case, high-precision position control is required.

[0008]

In order to simplify the structure of a laser beam machine, it is desirable to carry out machining with one laser beam source.

However, a case where auxiliary heating is required together with the main processing such as welding or a case where laser beams having different energy intensities suitable for the dissimilar materials to be abutted are required can be easily dealt with by a single laser beam. Did not.

An object of the present invention is to provide a laser beam machine that can form a plurality of laser beam spots having desired properties using a single laser beam.

[0011]

SUMMARY OF THE INVENTION A laser beam machine according to the present invention has an optical transmission system for transmitting and emitting a laser beam, a plurality of surfaces in contact with edges, and an area of the laser beam incident on the plurality of surfaces. A beam splitting unit that splits a laser beam according to a ratio, a supporting unit that movably supports the beam splitting unit, and a beam splitting unit that splits a laser beam emitted from an optical transmission system at a variable splitting ratio; A condensing lens unit common to a plurality of laser beams emitted from the splitting unit, a condensing lens unit for condensing a plurality of laser beams at different positions, and the beam splitting unit and the condensing lens unit And a rotation drive mechanism for simultaneously and simultaneously rotating them.

[0012]

By using a beam splitting section that can split a laser beam at a variable splitting ratio according to an area ratio and a common condenser lens section for a plurality of split laser beams,
A plurality of laser beams having a desired energy intensity ratio can be obtained with a simple configuration. By the rotation driving mechanism, the beam splitting unit and the condenser lens unit can be integrally rotated, and the laser beam splitting direction can be set arbitrarily. By using these plural variable and movable laser beams, it is possible to perform main heating and auxiliary heating and various heating processes using plural laser beams having different laser energy intensities.

[0013]

FIG. 1 schematically shows the construction of a laser welding machine according to one embodiment of the present invention. The laser beam emitted from the laser oscillator is transmitted through the fiber and is emitted downward from the fiber tip 1 in the figure.

The laser light diverging and emitted from the fiber end 1 is collimated by a collimating lens 2 to become a parallel light beam. The parallel light beam travels straight and enters the roof prism 3. The roof-shaped prism 3 has a symmetrical entrance surface inclined left and right upward in the figure.

The roof-shaped prism 3 deflects the laser beam incident on the left half in the figure to the lower right, and deflects the laser beam incident on the right half in the lower left. Thus, the roof prism 3 plays a role of splitting an incident laser beam into two beams.

The two laser beams split by the prism 3 are condensed by the condensing lens 4 and condensed in different spots at different points. The position of the focal point is determined by the deflection (refraction) angle given by the prism 3, the distance between the prism 3 and the condenser lens 4, the focal distance of the condenser lens 4, and the like.

The roof prism 3 is a prism cell 6
, And the condenser lens 4 is retained in the condenser lens cell 7. The lower end of the prism cell 6 and the upper end of the condenser lens cell 7 are threaded to engage with each other. By screwing the condenser lens cell 7 into the prism cell 6, the two are integrated.

The collimating lens 2 is held in a collimating lens case 5. The fiber case holding the fiber tip 1 is fixed by screwing a thread formed at the lower end thereof into a thread formed at the upper end of the collimator lens case 5.

A bearing 8 is provided at the lower end of the collimating lens case 5, and a pulley 11 is connected to the opposite side of the bearing 8. A screw portion is formed at the lower end of the pulley 11, and is screwed into and engaged with a screw portion formed at the upper end of the prism cell.

That is, the prism cell 6 and the condenser lens 7 are integrated and held rotatably by bearings 8. Fiber tip 1, collimating lens 2,
The condenser lens 4 is arranged coaxially.

In the drawing, a fixed structure to which the collimating lens case 5 is fixed is disposed on the left side, and a stepping motor 9 is installed inside the fixed structure. The rotation shaft of the motor 9 extends downward in the figure and is connected to the pulley 10. The pulley 10 and the pulley 11 are arranged in the same height direction, and a belt 12 is connected around the pulley 10 and the pulley 10.

The diameter of the pulley 10 is smaller than the diameter of the pulley 11. The belt 12 is driven in accordance with the rotation of the motor 9, and the reduced rotation is given to the pulley 11. When the pulley 11 is rotated by being guided by the bearing 8, the pulley 11 is rotated.
The prism cell 6 and the condensing lens cell 7 coupled to the above rotate, and the prism 3 and the condensing lens 4 rotate.

The stepping motor 9 is provided with an encoder. By applying a predetermined number of pulses, the stepping motor 9 can be rotated by a predetermined angle. The rotation of the stepping motor 9 is reduced through the small pulley 10 and the large pulley 11 to rotate the prism 3 and the condenser lens 4 by a predetermined angle.

It should be noted that other driving methods such as gear driving and friction driving can be adopted instead of belt driving. In addition,
As will be described in detail later, the prism 3 is movable in the left-right direction in the figure, and by changing its position, the division ratio of the incident laser beam can be changed.

FIG. 2 shows a state in which the optical system is extracted from the laser processing machine described above, and the ridge of the roof prism 3 is arranged on the optical axis. The fiber tip 1 corresponds to the core of the fiber, and diverges and emits a laser beam from the end. The diameter of the fiber tip 1 is, for example, about 1 mm.

The collimating lens 2 which receives the laser beam diverging from the fiber end 1 converts the diverging laser beam into a parallel light beam. Focus f1 of collimating lens 2
Is substantially equivalent to the distance between the collimating lens 2 and the fiber end 1.

The two entrance surfaces of the roof prism 3 divide the incident laser beam into two and have symmetrical surface normals inclined at an angle θ with respect to the parallel laser beam. The exit surface of the prism 3 is flat, and the laser beam emitted from the prism 3 has a deflection angle inclined by δ from the original direction. The parallel laser beam emitted from the prism 3 is incident on the condenser lens 4 and is condensed and collected in two spots.

Assuming that the refractive index of the prism 3 is n, the angle θ is small, and the focal length of the focusing lens 4 is f2, the focusing spot diameter φD and the interval d between the focusing spots are φD = 1 mmφ × (f2 / f1) d = 2 × f2 × tan δ Here, δ (<or ≒) (n−1) θ.

That is, the diameter of the focused spot with respect to the fiber diameter is determined by the ratio of the focal length of the lenses 2 and 4, and the distance d between the focused spots is determined by the deflection angle of the prism 3 and the focal length of the focusing lens 4.

In the configuration shown in FIG. 1, the position of the prism 3 can be changed in the horizontal direction in the figure. Further, the prism cell 6 and the condenser lens cell 7 are of a screw type and can be removed from the pulley 11. Combining a prism and a condensing lens having desired characteristics, pulley 1
By screwing into 1, the beam splitting characteristics and the light collecting characteristics can be changed. From another viewpoint, the prism cell 6 or a plurality of sets of the prism cells constitute a beam splitting unit having a variable split ratio.

FIG. 3 is a diagram for explaining the function of the prism 3 in the prism cell 6. FIG. 3A shows a schematic top view of a prism cell, and FIG. 3C shows a change in optical characteristics accompanying a change in the position of the prism.

As shown in FIG. 3A, the prism 3 is held by a prism holder 13 and is supported in the prism cell 6 via an adjusting screw 19. The adjustment screw 19 has a right-hand and left-hand relationship with respect to the right and left, and holds the prism holder 13 horizontally by two sets of upper and lower. By adjusting the adjusting screw 19, the position of the prism 3 in the prism cell 6 can be adjusted right and left.

FIG. 3B shows the relationship between the prism 3 and the collimated laser beam L incident on the prism.
The prism 3a indicated by the solid line has its ridge Ta coincident with the center L3 of the laser beam L, and the laser beam L is evenly distributed by two.
Split into two beams.

The laser beam incident on the left slope of the roof prism 3a is refracted by the roof prism to become a laser beam Bb, and the laser beam incident on the right slope of the roof prism 3a is refracted by the roof prism 3a. ,
It becomes a laser beam Ba.

As described above, the edge Ta of the roof prism 3a is
Coincides with the center of the laser beam L, the laser beams Ba and Bb having two equal energy intensities
Is obtained.

Next, the roof prism is moved to the right,
The light beam L whose ridge Tb is located on the right side in the laser beam L
Suppose that it matched 4. In this state, the roof prism 3
The beam area incident on the left slope of b is large, and the beam area incident on the right slope is small.

The laser beam incident on the left slope of the roof prism 3b is refracted by the roof prism 3b to form a laser beam By, and the laser beam incident on the right slope of the roof prism 3b is To form Bx. The beam intensity of the formed laser beams Bx and By changes depending on the ratio of the areas of the laser beams incident on the left and right slopes.

Since the angle of the inclined surface of the roof prism is constant and the bottom surface thereof is kept horizontal, the angle in the traveling direction does not change even when the intensity ratio of the emitted beam is changed.
By driving the stepping motor 9 and rotating the bearing 8, the direction of laser beam division can be set arbitrarily.

FIG. 4 shows a laser welding machine shown in FIG.
The operation when performing butt welding is schematically shown. The objects to be processed 13 and 14 are arranged facing each other. Here, the ridge of the roof prism is decentered from the center of the incident laser beam, and the laser beam spot By has a large intensity.
It is assumed that a laser beam spot Bx having a small intensity is formed. It is assumed that the objects 13 and 14 move relative to the laser beam spots Bx and By without changing their relative positions.

Although the spot diameters are shown as different in order to indicate the magnitude of the intensity, the spot diameters are practically the same in practice because parallel light beams are collected. FIG.
(A) shows the operation when auxiliary heating is performed before welding.
A small laser beam spot Bx is arranged in front of the high-intensity laser beam spot By.
It is relatively moved rightward along the fourteen butting positions.

On the abutting surfaces of the processing objects 13 and 14, first, the laser beam spot Bx of small intensity is supplementarily heated, and the laser beam spot By of high intensity is irradiated in a preheated state. By irradiating the preheated workpiece with the main laser beam to perform welding, high-quality welding can be performed.

FIG. 4B shows a main laser beam spot B
The configuration in which the auxiliary laser beam spot Bx is arranged behind y is shown. After welding, when the workpiece is rapidly cooled,
This arrangement is suitable for the case where distortion or the like adversely affects cracks or the like.

The main laser beam spot By moves to the right side in the figure along the position where the workpieces 13 and 14 meet. Auxiliary laser beam Bx behind main laser beam By
Are arranged, and follow the same trajectory as the main laser beam while maintaining a predetermined interval.

The processed portion irradiated with the main laser beam By and welded starts cooling as the main laser beam By separates, but the auxiliary laser beam Bx is irradiated next, so that rapid cooling is prevented. And show a gradual temperature drop. Thus, by preventing the rapid cooling, high-quality welding can be realized.

FIG. 4C shows butt welding of different materials having different heat capacities and melting points. The processing object 13 has a higher heat capacity and a higher melting point than the processing object 14. Therefore, a large energy intensity is required to melt the workpiece 13.

The energy intensity ratio between the laser beam spots By and Bx is selected according to the energy intensity required to melt the workpieces 13 and 14. These two laser beam spots with different energy intensities are
By arranging the workpieces 13 and 14 on both sides of the butting position and moving the workpieces 13 and 14 along the abutting position, the workpieces 13 and 14 having different characteristics can be melted in an optimum state and welded. .

A lens-prism system having the above-mentioned fiber exit end having a diameter of 1 mm, a condensing spot diameter of 600 μmφ, and a condensing spot diameter interval of 1 mm was used.
Lap welding and butt welding of an 8 mm stainless steel plate were performed. 400W Y as laser light source
Using an AG laser, the energy intensity ratio is 5J: 15J =
Beam splitting was performed so as to be 1: 3.

A low intensity laser beam spot was used for preheating, and a high intensity laser beam was used for welding. The processing speed was 100 mm / min. By this preheating laser beam welding, a stainless steel plate was successfully welded. Compared to the case where one laser beam spot is defocused and spread and welded,
In the appearance of the weld bead, the welding according to this example gave better results.

It should be noted that a trapezoidal prism may be used instead of the roof prism to divide the beam into three. Preliminary heating, welding, and slow cooling auxiliary heating can be performed by the three-part beam.

FIG. 5 partially shows the configuration of a gas assist laser processing machine according to another embodiment of the present invention. In the present embodiment, a housing 16 having an assist gas inlet 15 surrounds the periphery of the prism cell 6 and the condenser lens cell 7 that hold the prism 3 and the condenser lens 4 at the laser beam emission portion.

The assist gas introduced from the assist gas inlet 15 is guided by the housing 16 and jets downward from the lower jet port 17. The opening of the lower jet port 17 is designed so as not to come into contact with the laser beam condensed via the prism 3 and the condensing lens 4 shown in the upper part of the figure. As the assist gas, oxygen or the like is used for cutting, and an inert gas or the like is used for the solvent.

Although the case has been described in which the roof beam prism and the trapezoid prism are used to divide the laser beam into two and three on a straight line, other division modes may be used. For example,
A prism having a polygonal pyramid shape such as a triangular pyramid may be used to obtain three or more beams. Beam splitting may be performed by using a roof mirror, a corner cube mirror, or the like instead of the prism.

Although the case of performing welding by laser processing has been described, it is also possible to perform laser cutting using a similar configuration. Even in such a case, it is considered that by dividing the laser beam and irradiating a plurality of points, the heating points are dispersed, and it is possible to reduce thermal distortion or the like applied to the workpiece.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0055]

As described above, according to the present invention,
By performing laser processing using two or more branched laser beams simultaneously, it becomes possible to perform higher-quality laser processing than conventional laser processing.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of a laser welding machine according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing an extracted optical system in the laser welding machine of FIG. 1;

FIGS. 3A and 3B are a plan view and a schematic view for explaining a configuration and a function of a prism cell 6. FIGS.

FIG. 4 is a conceptual diagram illustrating a procedure for performing butt welding using the laser welding machine of FIG. 1;

FIG. 5 is a schematic partial cross-sectional view showing a configuration of a gas assist laser processing machine according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber tip 2 Collimating lens 3 Prism 4 Condensing lens 5 Collimating lens case 6 Prism cell 7 Condensing lens cell 8 Bearing 9 Stepping motor 10, 11 Pulley 12 Belt 13, 14 Workpiece 15 Assist gas inlet 16 Housing 17 Lower part Spout L, B Laser beam

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 26/00-26/08

Claims (2)

(57) [Claims] 1. An optical transmission system for transmitting and emitting a laser beam, a beam splitting means having a plurality of surfaces in contact with edges, and splitting the laser beam according to an area ratio of the laser beam incident on the plurality of surfaces; A beam splitting unit for movably supporting the beam splitting unit, the beam splitting unit splitting a laser beam emitted from the optical transmission system at a variable splitting ratio, and a plurality of laser beams emitted from the beam splitting unit. A condensing lens unit that collects a plurality of laser beams at different positions, and a rotation driving mechanism that simultaneously rotates the beam splitting unit and the condensing lens unit simultaneously. Having a laser processing machine. 2. The laser beam machine according to claim 1, wherein the beam splitter emits the plurality of split laser beams in different directions by refraction.