JPS62203116A - Laser light irradiating device - Google Patents

Abstract

PURPOSE:To dispersing the energy of laser light uniformly and perform a uniform heat treatment, and to simplify the constitution of a device and reduce its cost by slanting the rotating shaft of a rotary mirror which reflects luminous flux from a laser light source to a body surface to its normal. CONSTITUTION:An image forming lens 3 is fixed to a holding cylinder 14, which is mounted at the inner periphery of a cylinder body 12. The rotating shaft 10a is provided slantingly to the normal 10b to the rotary mirror 10b. The rotary mirror 10 is clamped between holding frames 16 and 17 and fixed,the frame 17 is coupled with the output shaft 10a of a motor 13 through a coupling pin 18, and a bearing member 19 is also fixed to the output shaft 10a through the coupling pin 18. Therefore, the output shaft 10a is rotated by the motor 13 to rotate the bearing member 19, coupling pin 18, holding frame 17, holding frame 16, and rotary mirror 10 in one body.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser beam irradiation device that irradiates a spot-shaped laser beam onto the upper surface of a workpiece.

(Prior Art) Conventionally, a laser beam irradiation device hardens a predetermined range of the upper surface of the workpiece by emitting, for example, a spot-shaped laser beam onto the upper surface of the workpiece and scanning the upper surface of the workpiece along a predetermined trajectory. It is used when heat treatment is performed.

However, in conventional laser beam irradiation devices, the spot-shaped laser beam irradiated onto the top surface of the workpiece itself has unevenness, so-called multimode energy distribution, so that the energy of the laser beam irradiated onto the top surface of the workpiece is within the predetermined range. There was a problem in that the heat treatment was not uniformly distributed within the interior of the container, resulting in uneven heat treatment.

To avoid such problems from occurring.

As a conventional laser beam irradiation device, (1) as shown in FIG. It is configured to form a spot-shaped laser beam 1 on the upper surface of a workpiece 2 by shifting the focus position of the imaging lens 3.

(2) As shown in FIG.
By oscillating and inverting the vibrating mirror 4 that reflects the condensed light beam from the workpiece toward the upper surface 2 of the workpiece, a spot-shaped laser beam l is generated as shown in FIGS. 5 and 6.
It is configured to vibrate in the direction of the arrow in the figure.

(3) As shown in FIG. 8, a concave mirror 5 formed by pasting a large number of minute plane mirrors 5a is provided, and the collimated light beam from the laser light source is configured to form an image on the upper surface 2 of the workpiece. be.

However, in the conventional example (1) above, the workpiece E surface 2
The laser beam 1 formed on the top surface of the workpiece is only focused on the spot-shaped laser beam 1, and the energy of the laser beam 1 irradiated onto the upper surface 2 of the workpiece is not evenly distributed within the predetermined range, and the heat treatment In the conventional example (2) above, there is a problem when heat treatment is performed by scanning an area linearly extending in one direction with a spot-shaped laser beam l vibrated in the direction of the arrow in Fig. 6. However, as shown in FIG.
When rotating and scanning in the direction of the arrow in the figure above, the trajectory of the spot-shaped laser beam l vibrating in the direction of the arrow, that is, the trajectory 7 irradiated by the spot-shaped laser beam 1, has an outer diameter that is horizontally elongated and an inner diameter that is elongated. has a vertically elongated oval shape, and the width of the locus 7 is not constant, so the energy density of the spot-shaped laser beam 1 at the narrow part 7a of the locus 7 is equal to the energy density at the wide part 7b of the locus 7. The narrow portion 7a may be melted by the energy of the spot-shaped laser beam 1, and the mechanical configuration for swinging and reversing the vibrating mirror 4 is difficult.As shown in FIG. In the conventional technique (3), the laser beam l focused on the upper surface 2 of the workpiece by the concave mirror 5
Since the energy t is evenly distributed to some extent, the heat treatment is less uneven than the above two conventional examples, but since a large number of plane mirrors 5a must be aligned with the center of curvature of the concave mirror 5, The manufacturing cost of the concave mirror 5 is extremely high, making it uneconomical, and since there is a gap between each plane mirror 5a, there is a problem that the energy loss of the spot-shaped laser beam 1 is large.

(Problems to be Solved by the Invention) The present invention was made by focusing on such conventional problems, and in order to equalize the multimode energy distribution of laser light, it is possible to The incident light intersects the rotation axis perpendicular to the plane of the plane mirror rotating within the plane, and by rotating the plane mirror, which is slightly tilted around a swing axis provided in the same plane, around the rotation axis. The object of the present invention is to provide a laser beam irradiation device that can uniformly heat the upper surface of an object through the rotating plane mirror, has an extremely simple configuration, and is inexpensive to manufacture.

(Means for Solving the Problems) The gist of the present invention for achieving the above object is to provide a laser beam irradiation device that irradiates a spot-shaped laser beam onto an object surface, including: a laser oscillator; and an imaging lens that forms an image of the incident parallel light beam onto the object surface.

a fixed mirror that reflects a condensed light beam from the imaging lens; a rotating mirror that is rotatable about a rotation axis and that reflects the light beam reflected by the fixed mirror toward the object surface; a driving source for rotating the mirror, the reflected light and the incident light of the rotating mirror intersect with each other, and the rotating axis of the rotating mirror is tilted with respect to its normal line. It resides in the light irradiation device.

(Function) In the above laser beam irradiation device, when the rotating mirror is rotated, the rotation axis of the rotating mirror is inclined with respect to its normal line, so that the spot-shaped laser beam formed on the upper surface of the workpiece is It rotates in a ring shape.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. Note that the same parts as in the conventional example are given the same reference numerals.

1 to 4 show an embodiment of the present invention, FIG. 1 is an overall view of a laser processing machine, and FIG. 2 shows the main parts of a laser beam irradiation device according to an embodiment. FIG.

In the laser processing machine shown in FIG. 1, a laser beam irradiation device 8 is installed in a vertically movable head in order to heat-treat the L side of a workpiece 2 placed on a table T that moves on a water movable surface on a bed B. A control panel CM for controlling the movements of the table T and head H is mounted on the front of the processing machine, and a laser oscillator operation panel CL is also arranged on the front of the processing machine.

Furthermore, a laser beam oscillator is provided on the side of the processing machine, and its beam is guided to an irradiation device via a mirror.

As shown in FIGS. 2 and 3, the laser beam irradiation device 8 has a fixed mirror 9 90' with respect to the horizontal plane in order to condense the parallel light beam from the laser oscillator onto the upper surface of the workpiece 2.
An imaging lens 3 that is tilted and fixed to the first holding part 11 and forms an image of the reflected light beam from the first fixed mirror 9, and a second fixed mirror that reflects the condensed light beam from the imaging lens 3. 23
, a rotating mirror 10 that is rotatable around a rotation axis 10a and that reflects the light beam reflected by a second fixed mirror 23 toward the workpiece 2, and a cylinder 12 that holds an imaging lens 3 at one end and is fixed thereto. It is comprised of a mirror 23 and a second holding part 21 holding a motor 13 with a rotating mirror 10 provided at the output shaft end.

The imaging lens 3 is fixed to a holding cylinder 14 , and the holding cylinder 14 is attached to the inner circumference of the cylinder body 12 .

The first fixed mirror 9 is fixed inside a mirror fixing part 15, and this mirror fixing part 15 is fixed to the outer surface of the first holding part 11.

Furthermore, the second fixed mirror 23 is fixed inside a mirror fixing part 22, and this mirror fixing part 22 is fixed to the outer surface of the second holding part 21 at an angle.

As shown in FIGS. 2 and 3, the rotating shaft 10a (
In FIG. 1, the center line of the rotating shaft 10a is indicated by 10a''), which is inclined with respect to the normal 10b of the rotating mirror 10.

The rotating mirror 10 is held and fixed by holding frames 16 and 17, which are connected to the output shaft 10a of the motor 13 via a connecting pin 18. A bearing member 19 is also fixed to the output shaft 10a via this connecting pin 18.

Therefore, the output shaft 10a is rotated by the motor 13, which causes the bearing member 19, the connecting pin 18, and the holding frame 1 to rotate.
7. The holding frame 16 and the rotating mirror 10 are configured to rotate integrally.

Here, the rotation speed of the one-rotation shaft 10a is, for example, 6000 rpm.
That's about it.

The motor 13 is held in the upper opening 12a of the second holding part 21.

The lower opening 12b of the second holding part 21 has a rotary mirror 10
A second light projecting cylinder 20 is installed at the part that projects the luminous flux reflected by the
It is attached to the lower part of the holding part 21.

Further, the upper surface of the workpiece 2 is placed a on the table T shown in FIG. This table is a horizontal plane E
It is made movable.

In the laser beam irradiation device 8 having the above configuration, the parallel light beam from the laser light source is condensed by the imaging lens 3, and this condensed light beam is transmitted to the first and second fixed mirrors 9, 23.
The light is then reflected by the rotating mirror 10, and is once focused on the focal point i3a, and then irradiated onto the workpiece 2. therefore,
As shown in FIGS. 2 and 4(a), a laser beam slightly missed on the surface of the work lh, that is, a spot-shaped laser beam l is formed on the upper surface of the work 2.

At this time, the rotating shaft 10a is rotating at a high speed of about 6000 rpm due to the rotation of the motor 13.

This rotation of the rotating shaft 10a causes the bearing member 19, the connecting pin 18, the holding frame 17, the holding frame 16, and the rotating mirror 10 to
rotates as a unit.

At this time, as described above, the rotating shaft 10a is connected to the rotating mirror 1.
Work 2 is slightly tilted with respect to the normal 10b of 0.
The spot-shaped laser beam 1 irradiated onto the upper surface rotates at a high speed at the same rotation speed as the rotating shaft 10a and the rotating mirror 10, as shown by the ring 30 in FIG. 4(A).

At this time, when the upper surface of the workpiece 2 is rotated by circularly moving the table on the horizontal plane, the spot-shaped laser beam 1 rotating at high speed in the shape of a ring 30 is generated as shown in FIG. 4(a).
The workpiece 2 is moved (scanned) along a circular trajectory 31 shown in FIG.

As a result, the entire circular orbit 31 is irradiated with the laser beam 1 in the shape of a spout and is heat-treated.

In this way, the spot-shaped laser beam 1 moves along the circular orbit 31 while rotating at high speed as shown by the ring 30 which is almost a perfect circle on the upper surface of the workpiece 2, and the circular orbit 3
1 is constant, the energy of the laser beam irradiated over the entire circular orbit 31 on the upper surface of the workpiece 2 is evenly distributed. As a result, even and uniform heat treatment was performed over the entire circular orbit 31.

In addition, by moving the table on which the workpiece 2 is placed in a desired direction depending on the range to be heat-treated, the spot-shaped laser beam l rotating at high speed along the ring 30 can be directed onto the upper surface of the workpiece 2 in a desired direction. can be moved in the direction of The width of this movement locus in the desired direction is constant as in the case where the circular orbit 31 is drawn.

Ideally, the laser beam 1 irradiated onto the top surface of the workpiece is reflected from the rotating rotating mirror 10 and irradiated onto the top surface of the workpiece, so that the locus of motion becomes a perfect circle as shown in FIG. 4 (a). be.

However, although the light reflected from the rotating mirror IO can form a perfect circle if the angle of incidence with respect to the normal is zero, this is difficult due to structural constraints.

Therefore, by reducing the incident angle of the laser beam, a shape close to a perfect circle can be obtained.

When the angle of incidence with respect to the normal line of the rotating mirror 10 when the rotating mirror 10 is tilted with respect to the rotation axis is φ, the shape drawn on the projection plane can be analyzed as described in detail below.

This will be explained based on the principle diagram shown in FIG.

O2: Center of rotation of the mirror OPo: Normal line to the mirror surface at the center of rotation Plo: Incident light P2O: Reflected light P3: Foot surface of a perpendicular line drawn from Pl to the straight line OPo,
It is assumed that point PI is on the y,z plane.

(x!-0) If the angle between PIO and the two axes is φ, and pto 4,
The coordinates of point P1 are (0, -1 sinφ, flcosφ') −・
- (1) When the mirror is tilted at an angle with respect to a plane perpendicular to the mirror rotation center axis OZ, the angle formed by the z-axis and OPo is a pot. now.

0Po-see, OQ-ρ then z6m 1cos IL ρ-1sin leIOmρco's θmJ1cosθ-sin gyo
= ρ sin 0 m1 sin θ − sin
IL Therefore, the coordinates of point PO are (lcos θ−+'ing, , fL sin θ・
5rnp-, l cos x) (a) The direction cosine of the straight line - is, Next, to find one point P3, directly from point P1! 1PoO
When finding the perpendicular line drawn to h, since point P3 is on the straight line POOh, 73 = xztanθ CaSθ ・tan u.

The equation of a perpendicular line is to find a straight line connecting points P1 and P2, and the direction cosine of (o) direct & IP+h is PIP3-L. Since this is orthogonal to the straight line -PLIO, it is cosθ-5inILX −+ sinθ-s+ngX
(2)XL! 3 (cog o s:n IL +
sin θ ・s inp, -tan θ
◆cos 4°)+s
inθ ・sin le・CoSθ −tang lsin φ−cost −fLsin φ
0 Follow! 3 = 1-cosθ-srng (casp, -c
osφ-5irl ・5rn4・sinφ) Similarly, y3- x3tan O-10sinθ-sjng (
cosg ・casφ −5inθ−5rnuL−si
nφ) z3- *l cod (cost-co
sφ-5inθ・cosθ−tang sin end・sinφ) Next, the coordinates of point P3 are determined.

P3 is the midpoint between Pl and 22, so x= 2!3-! l, yz=2y3-y+, 22-
223-21 Here! l"Os Y+--1sin
Since φ+21 fLcosφ, x21I 2!3 −2Jl ・casθ °5in
IL (CO8IL +CO8φ-5inθ-5in
g °sinφ)! 2- 2y3+l sin φ=21 sin
θ−s+nIL(cosg ・cosφ−5inθ −
sing ・sinφ)+jLsinφ22−
2z3-1 cog φm21 cas g (c
asg-casφ-5inθ-sing-sinφ)
-ucos φ (c) If the direction cosine of the paleolinear pressure is ta, then -sinθ-sing ・sinφ) -cosφ-5inθ・sing ・sinφ) +g
inφ−5in θ・sin#L−sinφ) −5i
nφ(d) Find the point where the straight rain crosses the surface H shown in Figure 1θ.

The general formula for surface H (7) is AI + By + Cz +
Since the D-0 plane H is parallel to the X axis, A-02 so 0
When Y-0, B m -sin φ-D, C--cos φ-D
:, -s:n φ-D -y -cosφ-D-z
+ D = 0 Therefore, the formula for the mo surface H is sinφ・y + cosφ・z −1 Also, when substituting the formula for the straight line m into the formula for the mo surface H.

As shown in the figure, the origin is 0', the Y axis is taken, and the X axis is perpendicular to the plane of the paper.

At this time, -tanΦ Therefore, with the configuration shown in Figure 11, if we take the X-Y coordinates on the object as the origin O', then with the X axis perpendicular to the plane of the paper, cosa -2cosθ-5tnp, (cosg °
cosφ-ginθ-5jnIL・sinφ) cosβ g2sirO-sing (cosJL-c
osφ-5ino-sinp,.

−5Inφ)+sinφ CO57=2cos4(cas4−casφ−5i
n θ −5an JL −5in φ−CoSφ is obtained.

In other words, when calculating by inserting numerical values into the above formula, when the rotating mirror is tilted and rotated around the rotation axis, the laser beam incident at an incident angle φ is reflected onto the object plane by the rotating rotating mirror. It can be seen that the smaller the incident angle φ, the closer the drawn trajectory is to a perfect circle, and conversely, the larger the incident angle φ, the longer an ellipse is formed in the Y-axis direction.

In addition, according to the above embodiment, the ring 30 in FIG. 4(a)
The long axis X and short axis Y of the ellipse drawn along However, the overall shape can be adjusted to a state close to a perfect circle, and the diameter 1 of the spot-shaped laser beam 1 can be adjusted by changing the distance between the top surface of the workpiece 2 and the focal position 3a, so this The laser beam irradiation device 8 can be made compatible with various heat treatment operations by adjustment, and has versatility.

In the above embodiment, the rotating mirror 10 is rotated at 600° rpm.
It is rotating at a rotation speed of 8000 r.
It is not limited to pm.

Furthermore, the mirror lO is set to the normal tob of the output shaft 10a of the motor.
If a swinging motion is applied around the connecting pin 18 in synchronization with the rotation around the center, the ring 30 drawn on the surface of the workpiece 2-E can also be made into a perfect circle.

(Effect of the invention) According to the laser light irradiation device according to the present invention.

Rotation that reflects the light flux from the laser light source toward the object surface.By tilting the rotation axis of the mirror with respect to its normal line, when the rotating mirror is rotated, a spot-like shape is formed on the object surface. Since the laser beam rotates while drawing a ring, the energy of the laser beam irradiated onto the object surface is evenly distributed, allowing uniform heat treatment to be performed, and the structure is extremely simple, reducing manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is an overall oblique view of the laser processing machine, Figs. 2 and 3 show an embodiment of the present invention, Fig. 2 is a sectional view showing the main parts, and Fig. Sectional view along the ■-■ line in the figure, No. 4
Figure (a) is a projected enlarged view drawn on the object plane when the ring created by the rotation of the spot-shaped laser beam is approximately a perfect circle.
Figure (a) is an explanatory diagram when the ring is moved circularly on the object plane with an approximately perfect circle with an outer diameter formed by a vertically long ellipse, and Figure 5 is a schematic layout diagram of an optical system showing a conventional example. Figures 6 and 7
The figures show another conventional example; Fig. 6 is a schematic layout of the optical system, Fig. 7 is an explanatory drawing showing how a spot-shaped laser beam moves on the object plane, and Fig. 8 9 is a schematic layout diagram of an optical system showing another conventional example, FIG. 9 is a principle diagram (1) of the trajectory of the reflected light drawn on the object surface when the rotating mirror is rotated with an inclination of P, and FIG. 10 is 11 is a diagram (2) of the same principle as described above, and FIG. 11 is a diagram (3) of the same principle as described above. 1...Spot-shaped laser beam 2...Workpiece 3...Imaging lens 8.
... Laser light irradiation device 9 ... Fixed mirror 10 ... Rotating mirror 1
0a... Rotation axis 10b... Normal line Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 8 Figure 9

Claims (1)

[Scope of Claim] A laser beam irradiation device that irradiates a spot-shaped laser beam onto an object surface, comprising: a laser oscillator; an imaging lens that images a parallel beam incident from the laser oscillator on the object surface; , a fixed mirror that reflects the condensed light beam from the imaging lens; a rotating mirror that is rotatable about a rotation axis and that reflects the light beam reflected by the fixed mirror toward the object surface; and the rotating mirror. and a drive source for rotating the rotating mirror, wherein the reflected light and the incident light of the rotating mirror intersect with each other, and the rotating axis of the rotating mirror is inclined with respect to its normal line. Laser light irradiation device.