JPS5932186A - Output control system for silent discharge type pulse laser device - Google Patents

Abstract

PURPOSE:To enable to form a silent discharge type pulse laser device as prescribed irrespective of the forming speed by varying the intermittent frequency of an intermittently applied voltage, the rate of voltage application time and voltage zero peak value and the like in response to the processing speed from a processing speed sensor. CONSTITUTION:A high frequency wave is applied in a pulse state through a transformer 5 from a high frequency power source 6 between a metal electrode and a dielectric electrode 2. The pulse laser output is applied through a condensing lens 12 to a moving article 13 to be processed. A forming speed sensor 14 detects the moving speed of the article 13 to be processed, and controls the output of an application voltage control circuit 15 with the detected output. The intermittent voltage output of the circuit 15 is applied to the power source 6. In this structure, any two or more of the intermittent frequency of the intermittently applied voltage of the circuit 15, the rate of the voltage application time, the voltage zero peak value and the discharge power and current are varied in response to the processing speed from the sensor 14. In this manner, the prescribed processing can be performed irrespective of the processing speed, the material can be saved, and the processing time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an output control method for a silent discharge pulse laser device, and particularly to an applied voltage control method for a pulse laser device in laser processing.

Conventionally, there is one shown in FIG. 1 as a typical example of this type of laser device. In this rotation, 1 is a metal electrode and 2 is a dielectric electrode. Metal electrode 1 is grounded 3, lightning induced, body 1
! The pole 2 is composed of a metal part 21 and a dielectric material 22 covering it. 4 is a discharge space between the electrodes 1 and 2;
5 is a transformer, and 6 is a high frequency power source. 1 is a total reflection mirror, 8 is a partial reflection mirror, and the total reflection mirror I, the partial reflection mirror 8, and the discharge space 4 form an optical co-photographer.

9 An arrow indicating the flow of Gt-laser gas, 10 an arrow indicating the laser output, 11 a bending mirror that bends the laser output, 12 a condensing lens, and 13 a workpiece moving at a speed V.

Figure 2 is a diagram showing the voltage waveform and oscillation output waveform applied to the silent discharge pulse laser device. Figure 2 (a) shows the applied voltage waveform, VO, is the zero peak value of the high frequency voltage, To = l /f indicates the high frequency voltage period, T indicates the applied voltage pulse width, and T2 indicates the pulse interval. Figure 2 (tb) shows the oscillation output waveform, W, (pk) is the peak value of the oscillation output, T is the pulse width of the oscillation output, and i'', is the oscillation delay time. The laser gas used in the pulsed laser device is carbon dioxide (CO2), nitrogen gas (N,
), helium gas ()-(e) with a molar fraction of 5-60-35° and a pressure of about 200 Torr.

Next, the operating pressure of the silent discharge type pulse laser device will be explained. K between the metal pole 1 and the dielectric electrode 2, high frequency!
#! 6 through the transformer 5, the frequency f as shown in FIG. 2(a). , zero peak value V. .

(8KV) high frequency pulse width 'I'l (0,5r
ns), and is applied in a pulsed manner with a pulse interval 'I'2 (0,51 nS).

The lifetime of the excited molecules of the laser is about 100 μs, and the period T of the applied high-frequency voltage. = ear is approximately 10 μs, so the laser output becomes a pulse-like one as shown in Fig. 2 (tb). That is, it is a pulse-like output with a width Tp having a cycle of period T, +T. The pulse width T of this output pulse,
, is the pulse width T of the applied pulse, which is smaller than 0.3 m
This is because an oscillation delay time T of about 0.2 m5 is required from when the voltage is applied until the output pulse rises. Therefore, the relationship between the pulse width T of the applied 'α pressure, the oscillation delay time TI, and the output pulse width T is T1+T.

If the laser output is emitted and laser processing is performed under the above conditions, the processing performance will change depending on the processing speed.

FIG. 3 shows the pattern using a ceramic scribinder (marking process) as an example. In Fig. 3(a), the machining speed v = 1 m/min, and in Fig. 3 tb), v = 2 m.
This shows the state of scribing when the speed is /min. As is clear from Fig. 3, the change in machining speed
), major axis A, minor axis B.

The hole spacing C2 and the penetration depth D vary. Here, the major axis A, minor axis B, hole interval C2, melt penetration depth I) are each a function of the machining speed V, and the following (1) to (3)
) can be shown by the formula.

A-T-v...River...River...
...(11B-D" W (p k ) ・v-
' ・=121C= (1', 4-T2) v
'E fp-' ·v --(3) In conventional pulsed laser processing, Fig. 3(a) shows.

(11) As shown in K1, the machining accuracy varied greatly depending on the machining speed V. The reason for the difference was that the machining area per pulse of the laser output differs from the machining speed vK, and the input energy per 130 unit length of the workpiece differs.

In this invention, the above points are considered to be cancerous, and the pulse wave number f2 and the duty α. , the zero peak value V of the applied voltage. 1. By changing two or more discharge power wd and discharge current ■ according to the machining speed 1/with a certain relationship, the heel output per pulse can be adjusted regardless of the machining speed V or the IC. We provide an output control method for a silent discharge pulse laser device that can perform constant scribing, drilling, etc. regardless of the machining speed V and the machining area and approximately equal input energy per 130-jaw length of the workpiece. The purpose is to do something. The present invention will be explained below based on the drawings.

FIG. 4 is a diagram showing a silent discharge type pulse laser device as an embodiment of the present invention. In this figure, parts given the same reference numerals as those in FIG. 1 indicate the same parts, and therefore their explanation will be omitted. 14 is a processing speed sensor that detects the moving speed of the workpiece 13; 15 is an applied voltage control circuit that controls applied voltage and pressure; 16 is an applied voltage from the high-frequency power source 6 controlled by the applied voltage control circuit 15; This is an example of a waveform.

Next, regarding the operation of the silent discharge type pulsed laser device, L'-
I will explain. First, if the machining area per 1 pulse of laser output is constant regardless of the moving speed of the workpiece 13, that is, the machining speed vlC, then the major axis A shown in equations (1) and (3) above is , it is sufficient that the hole interval C remains constant regardless of the machining speed V. The above formula (11) can be rewritten as follows〇= C1Tlv +C, A = C1i,'z v + C2...
(4) Therefore, by applying the following two items of applied voltage, the machining area per output pulse becomes independent of the machining speed V. C,, C2 is a constant, and the pulse frequency f is set to (1) v-CI fp.

are synchronized with the machining speed vK.

(11) Synchronize K Chufu αゎ with machining speed V so that αD = CI TIV +C2.

Here, the pulse width of the applied voltage +lI, == (p-1α
. FIG. 5 shows the measurement results of the oscillation delay time Tl. As clearly shown in FIG. 5, when the pulse width is 0.3 ms or more, the oscillation delay time is approximately constant at about 0.2 ms.

Next, in order to make the input energy per unit length of the workpiece 130 constant regardless of the processing speed V, it is necessary to satisfy the following equation (5) from the above equation (2).

Wr'pk)・v-'=constant ・・・・・・・・・
(5) Applied voltage zero peak value V. , and the oscillation output peak value W, (pk) have a relationship as shown in FIG. , W, (1) k ) ” (Vop %”op
) '・・・・・・・・・16) can be expressed as 1°. From equations (5) and (6) above, by applying the following (lli) to the applied voltage with C and l as constants, the input energy per unit length of the workpiece 130 is related to the processing speed V. Can you make it constant?

(ill (V., -v".-v-' = C3, therefore, V,, "V op + C, v...
・・・・・・・・・・・・・・・・・・(7) The applied voltage zero peak value■. Synchronize Il+ with machining speed V.

Taking ceramic fly pink as an example, FIGS. 7(a) and 7(b) show the case where pulse frequency r, duty αDft and machining speed V are synchronously controlled, and the applied voltage zero peak value V. FIGS. 8(a) and 8(b) show the case where p is also controlled in synchronization with the machining speed V at the same time. In Figures 7 and 8, each figure (a) shows the machining speed v = 1 m/m i
n, each (b) figure shows the case of v = 2 m/min. D
is changing from the machining speed vK. In FIG. 8, regardless of the machining speed V, +ji uniform machining accuracy can be obtained.

Figure 9 shows the emission IW, [force Wd and oscillation output peak value W, (p
FIG. 10 is a diagram showing the relationship between the discharge current and the oscillation output peak value W, (pk).

In FIGS. 9 and 10, the oscillation output peak value Wr (pk
) is 00, the discharge power and discharge ml flow, that is, the threshold discharge at which laser oscillation occurs, m, the power and the threshold discharge current are Wd, It. The relationship corresponding to the above (llllI) can also be considered for the discharge power Wd, radiation, 'i, and current IK.In other words, when laser oscillation occurs The discharge power W becomes Wd=W d+C4v'
) By synchronizing K with the machining speed V, the input energy per length of the workpiece m can be increased at a constant rate, which is related to the speed V. Similarly, the Jd roller threshold value of laser oscillation can be Regarding the discharge current B, let C3 be a constant and I
” l −4−C!l v By synchronizing the discharge current] with the machining speed V, the workpiece 1
30 The input energy per unit length can be made constant regardless of the processing speed V.

Note that this invention can be applied to general processing, and is also effective for, for example, punching holes in paper.

As explained above, the output control method of the silent discharge pulsed laser device according to the present invention is based on any two of the continuous frequency of the intermittent applied voltage, the ratio of the voltage application time, the voltage zero peak value, the discharge power, or the discharge current. By synchronizing the above relationship with the machining speed, or by changing the discharge power or discharge current in a certain relationship according to the machining speed instead of the voltage zero peak value, it is possible to perform constant machining regardless of the machining speed. For example, machining can be carried out even before the machining table is busy at a constant speed, resulting in material savings and shortening of machining time.In addition, machining speed can be reduced depending on the machining shape. It also has the excellent effect of being able to perform processing with uniform accuracy even when changes are required.

[Brief explanation of drawings]

Figure 1 is a principle diagram showing the configuration of a conventional silent discharge pulse laser device, Figure 2 (a) is its applied voltage waveform diagram, Figure 2 (+3) is its oscillation output waveform diagram, and Figure 3 +a). , (b
) is a diagram showing an example of ceramic scribing using a conventional pulse laser, FIG. 4 is a diagram showing a silent discharge type pulse laser device according to the present invention, and FIG.
Figure 6 is a diagram showing the measurement results of l, and the applied voltage is zero peak voltage V. , and excavation output peak value W,! Figures 7(a), (b), and 8(a) show the relationship with pk).
), (b) is a diagram showing the relationship between the oscillation output peak value and discharge power of ceramic fly pink and the oscillation output peak value and discharge current according to the output control method 29 of the silent discharge pulse laser device according to the present invention, FIGS. 9 and 10 are diagrams showing the relationship between the discharge power Wd, the discharge current ■, and the oscillation output peak value W, (pk), respectively. In the figure, 1 is a metal electrode, 2 is a dielectric electrode, 4 is a discharge space,
5 is a transformer, 6 is a high frequency power supply, 1 is a total reflection mirror, 8 is a partial reflection mirror, 11 is a benzo ink mirror, 12 is a condensing lens, 13 is an object to be processed, 14 is a processing speed sensor,
15 is an applied voltage control circuit, 21 is a metal part, and 22 is a dielectric. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno (1 other person) Figure 7 (b) Figure 8 Figure 9 Figure 10 Figure 11 Secretary 1 Ru1, 'I (f'l table small Ti")" M (5
7-t 424 o s No. 2 Invention') Name 44:
No 7" Output control method of discharge type pulsed laser device 3, Ura i1i k 1' ancient table R piece 1 + V section 4, agent 6 Drawing subject to amendment 7 Contents of amendment drawing Fig. 8 as attached. Correct. 8th λ (b)

Claims (1)

[Claims] At least one of the two electrodes is a dielectric electrode having a structure in which the metal surface is coated with a dielectric, and a high frequency voltage is intermittently applied between the two electrodes to generate a pulse oscillation output. Silent discharge pulse laser device button - [, a processing speed sensor that detects the moving speed of the workpiece, an applied voltage control circuit that controls the applied voltage based on the output of this processing speed sensor, and outputs an intermittent applied voltage. The applied voltage control circuit controls the intermittent frequency of the intermittent applied voltage, the ratio of the voltage application time, the zero peak value of the voltage, or the voltage release value. ,
The present invention is characterized in that two or more of m power or discharge current are changed according to the machining speed from the machining speed sensor to generate a pulse oscillation output that performs predetermined machining regardless of the speed of the workpiece. Output control method for silent discharge pulse laser equipment.