JPH0489193A - Laser beam machine - Google Patents

Abstract

PURPOSE:To allow high-speed and exact laser processing of a time division system by admitting the visible laser beam projected coaxially with laser beams via a turning mirror to distribute light in a radial direction to position sensor. CONSTITUTION:The laser beam emitted from a laser oscillator 1 is reflected by a dichroic mirror 4 and is condensed by a condenser lens 5. The turning mirror 6 which reflects this light and distributes the light in the radial direction around an incident optical axis 10 is driven by a galvanometer 8 to time- dividedly admit the laser beams to the end faces of plural optical fibers 7a to 7c. The visible laser beam from a visible laser oscillator 11 provided coaxially with the optical axis of the above-mentioned laser oscillator 1 is introduced to the above-mentioned condenser lens 5 and is reflected and distributed by the above-mentioned turning mirror 6 so as to make incident on the position sensors 19a to 19c provided in correspondence to the positions of the above-mentioned plural optical fibers 7a to 7c. The laser beam switching system having high-speed switching performance and high reliability over a long period of time in combination is obtd. by adopting the above-mentioned angle correction system of the photoelectric type.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a laser processing device using, for example, a YAG laser.

(Prior art) Generally, when processing metal or other materials using a YAG laser, for example, when processing a workpiece by directly focusing the laser light obtained from a YAG laser oscillation device with a lens without using an optical fiber. In other cases, processing is performed through an optical fiber, that is, by condensing the light energy emitted from the optical fiber with a lens, and the present invention relates to a YAG laser processing apparatus using the latter optical fiber.

Furthermore, if YAG laser processing equipment using optical fibers is further classified, the laser light obtained from the laser oscillation equipment is
There are two methods: one method uses energy division to process multiple points at the same time, and the other uses time sharing to process multiple points in chronological order.
Each is used depending on its purpose. The present invention relates to a YAG laser processing apparatus that performs the latter time-series multi-point processing.

Now, FIG. 5 shows a typical conventional time-division type fiber optic optical system. In this Fig. 5, during operation, Y
A laser beam 2 oscillated by an AG laser oscillation device 1 is collimated by a collimator 3, enters a switching mirror 4, is reflected in a right angle direction, and travels along a reflection optical axis 5. This laser light is condensed by an incident lens 6, becomes a minute spot, and enters the end face of an optical fiber 7. This incident light is transmitted through the optical fiber 7 for a predetermined distance, exits from the output end face, is condensed again by another lens (not shown), and is used to process a workpiece (not shown).

One system of the input optical system has been explained above, but the other two
The same is true for the two lineages.

By the way, in the above case, in addition to the switching mirror 4, there are switching mirrors 8 and 9, and these switching mirrors 4, 8, and 9 move as shown by the arrows at any time in response to external signals, and The switching mirror designated by the signal is located on the axis of the incident optical axis 10. Laser light then enters the optical fiber 7 corresponding to the switching mirror 4, for example. In FIG. 5, the switching mirror 4 is located on the axis of the incident optical axis 10, or in boat fishing, the switching mirror is normally designated completely randomly.

Further, although the switching mirror 4.8.9 may be moved in the direction of the arrow as described above, there is also a method in which the switching mirror 4.8.9 is moved in a direction perpendicular to the figure (perpendicular to the plane of the paper). In any case,
When switching, it is necessary to move a stroke of about 30 mm.

(Problems to be Solved by the Invention) As described above, in the conventional device, the switching mirror 4.8
．． 9 requires a stroke movement of about 30 mm, and the direction of reflection of the laser beam reflected by the switching mirror must always be maintained in a constant direction with correct reproducibility.

For this reason, the moving mechanism of the switching mirror 4.8.9 must be sufficiently robust to withstand repeated operations, and since the switching mirror 4.8.9 and the holding mechanism have large inertia, it takes approximately It will take about 200m5.

Incidentally, since actual switching involves a round trip operation, it requires nearly twice as much time. Therefore, it is impossible to perform time-sequential switching at high speed.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a high-speed and accurate time-division laser processing apparatus.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a laser oscillation device, a dichroic mirror that reflects laser light emitted from the laser oscillation device, and a dichroic mirror that focuses the reflected light of the dichroic mirror. a condensing lens, a rotating mirror disposed to reflect the light of the condensing lens and distributing the light in a radial direction around the incident optical axis, a galvanometer for driving the rotating mirror; In the laser processing device described above, the laser processing device is composed of a plurality of optical fibers provided corresponding to the rotating mirror, and further includes a switching optical system provided so as to make the light incident on the end faces of the plurality of optical fibers in a time-division manner. A visible laser oscillation device is provided that is coaxial with the optical axis of the laser oscillation device, and the visible laser light from this visible laser oscillation device is guided to the above-mentioned condensing lens, reflected and distributed by the above-mentioned rotating mirror, and then distributed. This laser processing apparatus is configured to make visible laser light incident on position sensors provided corresponding to the positions of the plurality of optical fibers.

(Function) According to this invention, by employing a photoelectric angle correction system,
A laser beam switching system that combines high-speed switching performance and long-term high reliability can be realized.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The laser processing apparatus according to the present invention is constructed as shown in FIGS. 1 to 4, in which FIG. 1 is a perspective view showing the laser processing apparatus according to the invention, FIG. FIG. 4 is a plan view taken along line xx' in the figure and viewed in the direction of the arrow, and a block diagram showing a control system in the laser processing apparatus of the present invention.

That is, if the same parts as in the conventional example (FIG. 5) are given the same reference numerals, a He-Ne laser oscillation device 11, which is a visible laser oscillation device, is provided near the YAG laser oscillation device 1, and this He-Ne laser oscillation device 11 is provided near the YAG laser oscillation device 1. A deflection mirror 13 is located on the optical axis of the He-Ne laser beam 12 oscillated from the Ne laser oscillation device 11.
14 are provided.

On the other hand, on the optical axis 15 of the laser beam 2 emitted from the YAG laser oscillation device 1, a collimator 3, a dichroic mirror 4, and a deflection mirror 16 are arranged at predetermined intervals. On the optical axis 10 of the laser beam reflected by the dichroic mirror 4, a condenser lens 5 and a rotating mirror 6 are arranged at a predetermined distance on one side.

This rotating mirror 6 is attached to a so-called galvanometer 8 having, for example, a movable ring-shaped part movement mechanism, and its mounting is performed at an angle of 45'' to the reflecting surface of the rotating mirror 6 or the rotating axis 9 of the galvanometer 80. Furthermore, the rotating axis of the galvanometer 8 is coaxial with the incident optical axis 10. Therefore, as shown in FIG.
The deflection angles θ1 and θ2 of the reflected optical axes are the same as the rotation angle of the galvanometer 8. Further, the angle of the galvanometer 8 is determined depending on the applied DC current value, so the angle is controlled by controlling the current value.

Furthermore, a plurality of optical fibers "7" corresponding to the rotating mirror 6 are provided.
A % 7 b % 7 c (optical fiber 7 in FIG. 2) is provided, and a plurality of position sensors 19a, 19b, 19c (position sensor 19 in FIG. 2) are provided.

As shown in FIG. 3, each position sensor 19 a -
, 19b s 19 c consists of a center detector and two direction discrimination sensors. For example, in the position sensor 1.9a, the center detector 19a-1 detects that the YAG laser beam 2 is accurately incident on the optical fiber 7a. The direction discrimination sensor 19a-2 detects the deviation in the negative direction, and the direction discrimination sensor 19a-3 detects the deviation in the negative direction.
performs shift detection in the positive direction. Both direction discrimination sensors 19a-2 and 19a-3 are sensors for detecting the direction of deviation and correcting the rotation angle when the rotation angle of the rotation mirror 6 is incorrect for some reason. be.

It goes without saying that the other position sensors 19b and 19c have exactly the same functions and operations.

Further, on the other side on the optical axis of the laser beam reflected by the dichroic mirror 4, there is a partially transmitting mirror 17 and a lens 20.
, television cameras 21 are arranged at predetermined intervals, and the television cameras 21 are connected to a monitor television 22.

Furthermore, the control system in the laser processing apparatus of the present invention has a fourth control system.
It is configured as shown in the figure, and 24.42 in the figure is an amplifier circuit, 30.43 is an AND circuit, 32.33.34 is a digital setting device, 26.35 is a logic circuit, and 37 is three up/down counters. 40 is a galvanometer driver, 45 is a clock generation circuit, and 28 is a delay circuit.

Next, the operation of the laser processing apparatus of the present invention will be explained.

First, the YAG laser beam 2 oscillated from the YAG laser oscillation device 1 is collimated by the collimator 3 and enters the dichroic mirror 4 . The YAG laser beam reflected by the dichroic mirror 4 is not condensed by the condenser lens 5 and then enters the rotating mirror 6, and the reflected light from the rotary mirror 6 is still condensed by the condenser lens 5. The light becomes a minimum spot at the focal position of , and enters the end face of the optical fiber 7.

On the other hand, H oscillated from the He-Ne laser oscillation device 11
The e-Ne laser beam 12 is guided to the YAG laser oscillation device 1 by a deflection mirror 13 , 14 , travels along an optical axis 15 coaxially with the YAG laser beam 2 , passes through a collimator 3 and a dichroic mirror 4 , and is directed to a deflection mirror 16 . reach.

Furthermore, it is reflected by the deflecting mirror 16 and is transmitted to the partially transmitting mirror 17.
The light passes through the dichroic mirror 4 again, is condensed through the condenser lens 5, and then enters the rotating mirror 6.

The He-Ne laser beam 18 reflected from the rotating mirror 6 is sent to position sensors 19a and 19b.

19c. Each position sensor 1
．． 9a, 19b, 19c are optical fiber halves a, 7b,
7c, and for example, when the YAG laser beam 2 is incident on the optical fiber 7a, the He
-Ne laser beam 18 is a position sensor], 9 a
It is designed to be incident on .

The rotating mirror 6 is a slightly convex mirror, and is designed to have a long focal length when combined with the condensing lens 5.

That is, as shown in FIG. 2, by positioning the position sensor 19 at a position t behind the end surface position of the optical fiber 7, it is possible to magnify and detect minute positional angle deviations of the rotary mirror 6.

In the structure and operation of the optical system as described above, there are two points that are markedly different from the conventional ones.

(2) Since the laser beam is distributed depending on the angle of the rotating mirror 6, the inertia of the drive unit is small and high-speed rotation is possible.

■ Light is distributed radially around the rotation axis of the rotating mirror 60, so each optical fiber 7a s 7 b s7c
However, the incident conditions can be made equal.

Are these two points a decisive advantage compared to the past?
In practical terms, there is a problem to be overcome, and this invention provides a solution.

That is, the rotary mirror 6 is driven by the galvanometer 8 and emits a laser beam in a specified direction, or the optical fiber 7 disposed in front of the rotating mirror 6 is driven by a galvanometer 8 and has a diameter of 0.4 to 0.5 mm.
It has a minute diameter of about 6mm. Originally, the galvanometer 8 has excellent angular accuracy and angular resolution with respect to the excitation current, and in principle can be used sufficiently for the purpose of this invention. Due to drift or the like, the rotation angle of the rotation mirror 6 may change, albeit slightly.

In this optical system, it is extremely important to always keep the rotation angle accurate, as this slight deviation in the rotation angle will lead to a loss of the incident light beam and even cause damage to the optical fiber 7. be.

Next, we will discuss the operation to keep this rotation angle accurate at all times.

As already mentioned, each optical fiber 7a, 7b.

7C has a position sensor 19a corresponding to each
, 1.9b, and 19c are arranged, and their positional relationship with each other is perfectly maintained. Therefore, by monitoring which position of the position sensors 19a119b and 19c the HeNe laser beam 18 is incident on, it is possible to know the deviation in the rotation angle of the rotation mirror 6.

That is, in FIG. 3, consider the case where the He-Ne laser beam 18 is now incident on the position sensor 19a. In the figure, if it is incident on the center detector 19a-1, no deviation has occurred, or if it is incident on the direction discrimination sensor 19a-2 or the direction discrimination sensor 19a-3,
This means that there is a misalignment, and if it continues in this state, YA
G laser light cannot be incident.

Therefore, the rotation angle is automatically corrected by the following method, which will be described in accordance with an embodiment of the present invention with reference to FIG.

Now, if the rotation angle of the rotation mirror 6 deviates from a predetermined value to the + side, the He-Ne laser beam 18 enters the direction determination sensor 19a-3. A photoelectric signal 23 is output from the direction discrimination sensor 19a-3, amplified by an amplifier circuit 24, and
The signal is input to the ND circuit 30.

On the other hand, when the channel command signal 25 (a signal for selecting which optical fiber the laser beam should enter into) is input,
A timing signal 27 is output by the logic circuit 26,
The delay circuit 28 sends a determination command signal 29 to the AND circuit 30 after the rotation of the rotating mirror 6 is completed. The AND circuit 3o outputs an output signal 31 since both power inputs are in an active state.

Now, in order to determine the original rotation angle, the digital setting devices 32, 33, and 34 are used to correspond to channel 1, channel 2, and channel 3, respectively. The signals from the digital setters 32, 33, and 34 enter the logic circuit 35 and are selected by the channel command signal 36.

Now, if data from the digital setter 32 is selected, this signal is added to the up/down counter 37. On the other hand, the up/down counter 37 performs subtraction counting while receiving the output signal 31, and stops counting when the output signal 31 disappears. This reduced count number corresponds to the correction value.

That is, the digital signal 38 corrected in this way is
The voltage is converted into a DC voltage by the DA converter 39, and applied to the galvanometer 8 via the galvanometer driver 4o. Therefore, the reflected light of the He-Ne laser beam 18 from the rotary mirror 6 driven by the galvanometer 8 captures the center detector 19a-1, and the center detector 19
Signal 41 from a-1 is sent to amplifier 42 and AND circuit 43
After that, it becomes a laser emission permission signal 44 and is sent to the YAG laser oscillator 1.

Note that the clock generation circuit 45 is an up/down counter 3.
This circuit supplies 7 clock pulses.

[Effects of the Invention] As explained above, according to the present invention, by employing a photoelectric angle correction system, it is possible to realize a laser beam switching system that has both high-speed switching performance and high reliability over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a laser processing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is a
FIG. 4 is a block diagram showing a control system in the laser processing device of the present invention, and FIG. 5 is a plan view showing a conventional laser processing device. be. DESCRIPTION OF SYMBOLS 1... Laser oscillation device, 4... Dichroic mirror 5... Condensing lens, 6... Rotating mirror 7...
Optical fiber 8... Galvanometer, 19... Position sensor, 11... Visible laser oscillation device. 9a-3 Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] A laser oscillation device, a dichroic mirror that reflects laser light emitted from the laser oscillation device, and a condensing lens that condenses the reflected light of the dichroic mirror.
a rotating mirror arranged to reflect the light from the condensing lens and distribute the light in the radial direction around the incident optical axis;
It consists of a galvanometer that drives this rotating mirror, and a plurality of optical fibers provided corresponding to the rotating mirror, and a switching optical system that is further provided to make the light incident on the end faces of the plurality of optical fibers in a time-division manner. A laser processing device comprising: a visible laser oscillation device coaxial with the optical axis of the laser oscillation device; a visible laser beam from the visible laser oscillation device is guided to the condenser lens; A laser processing device characterized in that it is configured to reflect and distribute visible laser light by a rotating mirror and to make the distributed visible laser light enter a position sensor provided corresponding to the position of the plurality of optical fibers.