JP4833773B2 - Micro drilling method - Google Patents

Description

  The present invention relates to an improvement of a fine drilling method.

As a conventional fine processing method, first, a workpiece is irradiated with nanosecond laser light to preheat the workpiece, and then processed by irradiating the workpiece with femtosecond laser light. (For example, refer to Patent Document 1).
JP 2001-212865 A

FIG. 1 of Patent Document 1 will be described with reference to FIG. In addition, the code | symbol was reassigned.
FIG. 4 is a block diagram showing a laser processing apparatus that performs a conventional fine processing method. The laser processing apparatus 100 includes a YAG laser 102 that outputs a pulse laser beam (nanosecond laser beam) 101 and a femtosecond laser beam 103. And a titanium sapphire laser 104 that outputs.

  The pulse laser beam 101 output from the YAG laser 102 is reflected by the beam splitter 106, condensed by the condenser lens 107, and applied to the chromium film 111 formed on the quartz substrate 108.

  The femtosecond laser beam 103 output from the titanium sapphire laser 104 is reflected by the total reflection mirror 112, then passes through the beam splitter 106, and is applied to the chromium film 111 collected by the condenser lens 107.

  First, the pulse laser beam 101 is irradiated to the chromium film 111 to increase the temperature of the chromium film 111, and then the femtosecond laser beam 103 is irradiated to the chromium film 111, so that the chromium in a state where the thermal potential is high. The film 111 is vaporized and ablated.

  Since the femtosecond laser beam 103 has a very short pulse width and thus has a small pulse energy, it is convenient to accurately process a narrow range with the femtosecond laser beam 103 without affecting the heat. For example, when drilling a minute deep hole, since the processing is gradually performed, a long time is required for the processing.

  An object of the present invention is to provide a fine drilling method that can perform machining with high accuracy and can perform drilling at high speed.

The invention according to claim 1 is a pilot hole machining step of irradiating a member with a nanosecond laser beam to open a pilot hole, and a finishing machining step of irradiating the inner wall of the pilot hole with a picosecond laser beam to finish the inner wall smoothly. It is characterized by having.
As an action, the member is previously irradiated with nanosecond laser light to form a pilot hole, and then the inner wall of the pilot hole is irradiated with picosecond laser light to finish the inner wall of the pilot hole.

  The nanosecond laser beam has a larger pulse width than conventional ultrashort pulse laser beams such as picosecond laser beams and femtosecond laser beams, and the energy per pulse, that is, the pulse energy is large. Drilling deep holes at high speed.

  With a picosecond laser beam, the pulse width is smaller than that of a nanosecond laser beam and the irradiation time per pulse repetition period is short. Because it is difficult, the finishing accuracy of the inner wall of the pilot hole is improved and the inner wall of the pilot hole becomes smoother.

The invention according to claim 2 is characterized in that, in the pilot hole machining step, the nanosecond laser beam is irradiated without rotating the optical axis, and the member is evaporated and removed.
As an effect, when drilling is performed by rotating the optical axis with nanosecond laser light, the condensing position may be slightly decentered, so when rotated, the inner diameter of the pilot hole increases by the amount of decentration. However, if the optical axis is not rotated, the irradiation range can be reduced and the processing diameter can be reduced.

  According to a third aspect of the present invention, in the evaporative removal process of the pilot hole machining step, the layer thickness of the solidified portion that is once melted and solidified to form the pilot hole is 10% to 40% with respect to the inner diameter of the pilot hole. It is characterized by that.

  As an effect, when the pilot hole is opened by the evaporative removal process using the nanosecond laser beam, the solidified part that is once melted and solidified on the inner wall of the pilot hole is formed due to the large pulse energy. This solidified portion reduces the accuracy of the pilot hole.

  When the layer thickness of the solidified part exceeds 40%, the amount of processing in the finishing process, which is a subsequent process, increases, and a long time is required for processing. If the layer thickness of the solidified portion is suppressed to 10% to 40%, the processing time in the finishing process can be shortened.

The invention according to claim 4 is characterized in that the picosecond laser beam is condensed smaller than the inner diameter of the pilot hole, and the inner wall of the pilot hole is evaporated and removed.
As a function, if the picosecond laser beam is focused to be smaller than the inner diameter of the pilot hole, the inner wall of the pilot hole is irradiated to melt and evaporate the inner wall, and then removed gradually, the finishing accuracy of the inner wall of the pilot hole Will improve. Further, since the heat-affected zone is less likely to be generated by the picosecond laser light, the finishing accuracy of the inner wall of the pilot hole is further improved, and the inner wall of the pilot hole becomes smoother.

The invention according to claim 5 is characterized in that, in the finishing process, the picosecond laser beam is irradiated while rotating relative to the member.
As an effect, picosecond laser light is evenly applied to each part of the inner wall of the prepared hole, and the finishing accuracy of the inner wall is further improved. In addition, since the picosecond laser beam is not locally irradiated to the pilot hole, the heat affected zone is less likely to occur.

According to a sixth aspect of the present invention, in at least one of the pilot hole machining step and the finishing machining step, vapor generated by evaporating and evaporating the inner wall when the inner wall is irradiated with nanosecond laser light or picosecond laser light. Is sucked or pumped by a vapor removing device.
As an effect, the generated vapor is sucked or pumped by the vapor removing device, so that the nanosecond laser beam or the picosecond laser beam is not blocked by the vapor.

The invention according to claim 7 is characterized in that the peak output of the laser oscillator that oscillates the picosecond laser beam is 300 kW to 1 MW.
As an effect, when the peak output of the laser oscillator is less than 300 kW, for example, when the member is made of metal, metal evaporation hardly occurs and much time is required for evaporation removal processing.
When the peak output of the laser oscillator exceeds 1 MW, a heat affected zone is likely to occur on the inner wall of the prepared hole.

The invention according to claim 8 is characterized in that the non-irradiation time in the pulse repetition period of the picosecond laser beam is 500 times or more of the pulse width in the pulse repetition period.
As an effect, if the non-irradiation time in the pulse repetition period of the picosecond laser beam is less than 500 times the pulse width of the pulse repetition period, the amount of heat input to the member is increased, and the heat effect on the inner wall of the pilot hole Part tends to occur.

  In the invention according to claim 1, a pilot hole machining step of irradiating a member with nanosecond laser light to open a pilot hole, and a finishing machining step of irradiating the inner wall of the pilot hole with picosecond laser light to finish the inner wall smoothly Therefore, in the pilot hole machining step, the pilot hole can be opened at a high speed with a nanosecond laser beam having a large pulse energy. Further, in the finishing process, by irradiating a picosecond laser beam having a small pulse width, a heat-affected zone is hardly generated on the inner wall of the prepared hole, and the inner wall of the prepared hole can be finished with high accuracy and smoothness.

  In the invention according to claim 2, in the pilot hole machining step, the nanosecond laser beam is irradiated without rotating the optical axis, and the member is evaporated and removed, so the optical axis is rotated by the nanosecond laser beam. Compared to the case of drilling, the irradiation range of the nanosecond laser beam can be reduced, and a pilot hole with a small inner diameter can be formed.

  In the invention according to claim 3, when evaporating and removing in the pilot hole machining step, the thickness of the solidified part that is once melted and solidified to form the pilot hole is 10% to 40% with respect to the inner diameter of the pilot hole. Therefore, by controlling the layer thickness of the solidified part to 10% to 40% of the inner diameter of the pilot hole, the processing amount in the finishing process, which is a subsequent process, can be reduced, and the processing time can be shortened. Can do.

  In the invention according to claim 4, since the picosecond laser beam is condensed smaller than the inner diameter of the pilot hole and the inner wall of the pilot hole is removed by evaporation, the picosecond laser beam condensed smaller than the inner diameter of the pilot hole is collected. Thus, a small range of the inner wall of the pilot hole can be gradually removed by evaporation, and the inner wall of the pilot hole can be processed more accurately and smoothly.

  In the invention according to claim 5, in the finishing process, the picosecond laser beam is irradiated while being rotated relative to the member, so that the picosecond laser beam can be uniformly irradiated by each part of the inner wall of the pilot hole, The inner wall of the pilot hole can be finished more smoothly. Moreover, since the pilot hole is not locally irradiated, the heat affected zone can be made more difficult to occur.

  In the invention according to claim 6, in at least one of the pilot hole machining step and the finishing machining step, vapor generated by melting and evaporating the inner wall when the inner wall is irradiated with nanosecond laser light or picosecond laser light. Is sucked or pumped by the vapor removing device, so that the nanosecond laser beam or the picosecond laser beam is not blocked by the vapor, and can be finished satisfactorily.

  In the invention according to claim 7, since the peak output of the laser oscillator that oscillates the picosecond laser beam is set to 300 kW to 1 MW, evaporation removal processing of the inner wall of the pilot hole can be performed in a short time and the inner wall of the pilot hole is heated. The affected part can be made difficult to occur.

  In the invention according to claim 8, since the non-irradiation time in the pulse repetition period of the picosecond laser light is set to 500 times or more of the pulse width in the pulse repetition period, the non-irradiation time of the picosecond laser light is increased. By doing so, it is possible to make it difficult to produce a heat affected zone on the inner wall of the prepared hole.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is an explanatory diagram of a laser processing apparatus according to the present invention. A laser processing apparatus 10 includes a nanosecond laser oscillator 12 that oscillates a nanosecond laser beam 11 and an ultrashort pulse laser oscillator that oscillates a picosecond laser beam 13. 14, an amplifier 16 that amplifies the picosecond laser light 13 oscillated from the ultrashort pulse laser oscillator 14, a mirror 18 that reflects the picosecond laser light 17 output from the amplifier 16, and a picosecond laser light 17 And a mirror 21 that reflects the nanosecond laser light 11 oscillated by the nanosecond laser oscillator 12, a beam rotator 22 that changes a condensing position of the nanosecond laser light 11 or the picosecond laser light 17, and A condenser lens 24 for condensing the nanosecond laser beam 11 or the picosecond laser beam 17 onto a workpiece 23 (for example, a steel material), and the workpiece 23 are mounted. A suction device 27 for sucking vapor generated from the work 23 when the work 23 is irradiated with the nanosecond laser light 11 or the picosecond laser light 17, a nanosecond laser oscillator 12, an ultrashort pulse laser oscillator 14, It comprises a control device 28 for controlling the operation of the beam rotator 22 and the horizontal movement of the table 26. Reference numeral 31 denotes a suction duct provided in the suction device 27.

The nanosecond laser beam 11 is a pulse laser beam generated by pulse oscillation with the nanosecond laser oscillator 12 and has a pulse width of the order of nanoseconds, that is, the order of 10 ⁻⁹ seconds.
The nanosecond laser oscillator 12 uses YAG or the like as a laser medium (that is, a light emitting substance).

The picosecond laser beam 13 is a pulse laser beam generated by pulse oscillation in the ultrashort pulse laser oscillator 14 and has a pulse width on the order of picoseconds, that is, on the order of ^10-12 seconds.

  The ultrashort pulse laser oscillator 14 uses ytterbium as a laser medium. For example, a seed light laser capable of oscillating a seed light (seed light) laser having a pulse repetition frequency of 500 kHz to 100 MHz. It is an oscillator. Since such a laser oscillator for seed light is commercially available, it can be obtained at low cost.

First, a pilot hole machining process for making a pilot hole in the work 23 with the nanosecond laser beam 11 described above will be described next.
2 (a) to 2 (e) are operational views showing a prepared hole machining step by the laser machining apparatus according to the present invention.
In (a), adjustment is made so that the focal point of the condenser lens coincides with the upper surface 23 a of the work 23, and the upper surface 23 a of the work 23 is irradiated with the nanosecond laser beam 11. Note that D0 is a condensing diameter (that is, a spot diameter) of the nanosecond laser beam 11 at the focal point, for example, a condensing diameter D0 = about 100 μm.
Thereby, the upper surface 23a of the work 23 reaches the melting point and starts to melt. 23b is a melting part.

  When the cross-sectional shape of the nanosecond laser beam 11 is not circular, the cross-section may be circular by rotating its optical axis. However, when the optical axis is rotated, the portion irradiated with the nanosecond laser light on the workpiece is widened by the accuracy of the rotating device, and the processing diameter is increased.

  In this embodiment, since the optical axis of the nanosecond laser beam 11 is not rotated, the irradiation range can be reduced. However, since the irradiated portion of the work 23 may not be circular, it is processed so as to be circular together with finishing in the finishing process, which is a subsequent process. Therefore, there is no special process for processing into a circle.

In (b), the workpiece 23 irradiated with the nanosecond laser beam 11 has a larger melted part 23d than in (a).
Since the temperature of the central part of the melting part 23d is higher than that of the surroundings, the boiling point reaches the boiling point, and the steam 23e is actively generated. Therefore, the melt part 23d is pushed outward by the pressure of the steam 23e. When the vapor 23e blocks the nanosecond laser beam 11, the hole 23 in the workpiece 23 is obstructed, so that the suction is performed from the suction duct 31 of the suction device.

(C) shows the state in the non-irradiation time when the nanosecond laser beam is not irradiated. The part close to the base material of the melted part 23d shown in (b) is solidified to become a solidified part 23f, and an unsolidified melted part 23g remains inside the solidified part 23f.
Thereafter, irradiation and non-irradiation similar to (b) and (c) are repeated.

  (D) shows a state in which a pilot hole 23L penetrating from the upper surface 23a to the lower surface 23j of the work 23 is opened. 23k is a cylindrical solidified portion which is once melted during processing and solidified to form a surface layer of the pilot hole 23L, and 23m is a heat affected zone (layered portions indicated by a plurality of points) formed around the solidified portion 23k. , 33 is an inner surface of the pilot hole 23L.

The heat-affected zone 23m is a portion between the solidified portion 23k and a portion not affected by the heat of the work 23 (that is, a base material raw material region), and is a portion where the structure is changed with respect to the base material. is there.
Here, the inner diameter of the pilot hole 23L (that is, the inner diameter of the solidified portion 23k) is D1, the outer diameter of the solidified portion 23k is D2, the outer diameter of the heat affected zone 23m is D3, and the hole depth of the lower hole 23L (here, De equals the thickness of the work 23). The hole depth de of the lower hole 23L is, for example, at least 1 mm.
The layer thickness (D2-D1) / 2 of the solidified portion 23k described above is 10 to 40% of the inner diameter D1 of the pilot hole 23L.

(E) is a graph which shows the relationship between the output of nanosecond laser oscillator 12 (refer FIG. 1) which is an oscillator of the nanosecond laser beam shown to (a)-(c), and time, and a vertical axis | shaft is output. The horizontal axis represents time.
The output of the nanosecond laser oscillator changes in a pulse shape from zero to the peak output P1. In the figure, T1 is the pulse width, that is, the irradiation time of the nanosecond laser beam (that is, the pulse width T1 is on the order of ^10-9 seconds), T2 is the non-irradiation time of the nanosecond laser beam, and T0 is the pulse repetition period. It is. The pulse repetition frequency (oscillation frequency) obtained from this pulse repetition period T0 is, for example, 1 kHz to 50 kHz.

  In this way, by irradiating the workpiece with the nanosecond laser beam, which is a pulsed laser beam, for the irradiation time T1 at each pulse repetition period T0, the base material can be melted and evaporated stepwise to form the pilot hole.

  With nanosecond laser light, the irradiation time is longer than with picosecond laser light, so the pulse energy can be increased, the amount of evaporation removal can be increased, and the pilot hole can be opened at a higher speed. .

Next, the finishing process for finishing the inner wall of the pilot hole 23L of the work 23 with the picosecond laser beam 17 described above will be described.
3 (a) to 3 (d) are operational views showing a finishing process of the prepared hole by the laser processing apparatus according to the present invention.
In (a), in the pilot hole machining step, which is the previous process, the solidified portion 23k that reduces the accuracy remains on the surface layer of the pilot hole 23L, so this solidified portion 23k (or the solidified portion 23k and the surrounding heat affected zone) 23 m) is removed by the picosecond laser beam 17. In the present embodiment, the solidified portion 23k formed in the prepared hole 23L is used as an inner wall having a thickness, and the inner wall is removed by irradiating the picosecond laser beam 17 to form a smooth hole with high accuracy on the inner surface.

First, adjustment is made so that the focal point of the condensing lens coincides with the upper end surface of the solidified part 23k of the work 23, and the end face of the cylindrical solidified part 23k is always irradiated by the beam rotator. Change the position of the spiral irradiation. (When removing the solidified part 23k and the heat affected part 23m, the picosecond laser beam 17 is irradiated to both end faces of the solidified part 23k and the heat affected part 23m.)
Thereby, the solidified part 23k of the workpiece 23 is removed in a spiral shape.

  (B) shows the state in the middle of removal of the solidification part 23k. During the irradiation with the picosecond laser beam 17, the solidification part 23k reaches the boiling point and the vapor 23p is generated. Suction is performed to prevent the finishing process from being hindered by the steam 23p.

  As the finishing process progresses, it is better to suck by the suction duct 31b on the side opposite to the light incident side of the picosecond laser 17. This is because processing can be performed without blocking the laser beam. For example, it may be controlled by a control means (not shown) so as to increase the negative pressure of the suction duct 31b as compared with the distance from the light incident side to the focal position, or by using the suction duct 31a. Gas may be ejected from 31a to create an air flow, and the vapor 23p may be sucked together with the gas by the suction duct 31b from the side opposite to the light incident side.

  The removal of the solidified portion 23k is continued up to the lower surface of the work 23. Reference numeral 35 denotes a finishing completion hole in which the finishing process of the pilot hole 23L is completed, and the inner surface 36 of the finishing completion hole 35 is finished with high accuracy and smoothness.

During evaporation removal processing by the picosecond laser 17, a heat-affected zone is unlikely to occur in a portion close to the processing portion, that is, the finish completion hole 35 as described later. The inner wall 36 of the finish completion hole 35 is originally the heat affected zone 23m. However, even if the degree of heat affected by the heat affected zone 23m is processed by the picosecond laser 17, the inner wall 36 is hardly increased.
When both the solidified part 23k and the heat affected part 23m are evaporated and removed by the picosecond laser 17, the heat affected part hardly occurs in the base material adjacent to the heat affected part 23m.

  (C) is a plan view of the coagulation part 23k, and shows a state in which the coagulation part 23k is irradiated with the picosecond laser light 17 having a condensed diameter D4 rotated in the direction of the arrow. The condensing diameter D4 of the picosecond laser beam 17 is, for example, 5 μm.

(D) is a graph showing the relationship between the output and time of the ultrashort pulse laser oscillator 14 (see FIG. 1) which is an oscillator of the picosecond laser beam shown in (a) and (b), and the vertical axis is Output, horizontal axis represents time.
The output of the ultrashort pulse laser oscillator changes in a pulse shape from zero to the peak output P2. In the figure, T4 is the pulse width, that is, the irradiation time of the picosecond laser beam (that is, the pulse width T4 is on the order of ^10-12 seconds), T5 is the non-irradiation time of the picosecond laser beam, and T3 is the pulse repetition period. It is.

The non-irradiation time T5 is, for example, a time that is 500 times or more the pulse width T4.
The pulse repetition frequency (oscillation frequency) obtained from the pulse repetition period T3 is, for example, 100 kHz to 1.1 MHz.

  In this way, by irradiating the workpiece with the picosecond laser beam capable of increasing the energy density for the irradiation time T4 every pulse repetition period T3, the base material is instantaneously melted and evaporated step by step. The 23L solidified part 23k can be deleted and finished at high speed.

  In addition, when finishing with picosecond laser light, the pulse repetition period T3 has a non-irradiation time T5. Therefore, the heat input to the workpiece can be controlled by this non-irradiation time T5, and laser by continuous oscillation is used. Compared with light, the temperature rise in the vicinity of the irradiated part of the workpiece can be suppressed, and the heat-affected zone can be made difficult to occur.

  As shown in FIGS. 2 (a) to 2 (e) and FIGS. 3 (a) to 3 (d), the present invention firstly irradiates the workpiece 23 as a member with the nanosecond laser beam 11 as follows. It is characterized by having a pilot hole machining step of opening the hole 23L and a finishing machining step of irradiating the inner wall (solidified portion 23k) of the pilot hole 23L with the picosecond laser light 17 to finish the inner wall smoothly.

  Thereby, in the pilot hole machining step, the pilot hole 23L can be opened at high speed with the nanosecond laser beam 11 having a large pulse energy. In the finishing process, by irradiating the picosecond laser beam 17 having a small pulse width T4, a heat-affected zone is less likely to occur on the inner wall of the pilot hole 23L, and the inner wall of the pilot hole 23L can be accurately and smoothly finished. .

  Secondly, the present invention is characterized in that, in the pilot hole machining step, the nanosecond laser beam 11 is irradiated without rotating the optical axis, and the work 23 is removed by evaporation.

  As a result, the irradiation range of the nanosecond laser beam 11 can be reduced compared with the case where the drilling process is performed by rotating the optical axis with the nanosecond laser beam 11, and the pilot hole 23 having a small inner diameter D1 can be opened. it can.

  Thirdly, according to the present invention, in the evaporative removal process of the pilot hole machining step, the thickness of the solidified portion 23k that is once melted and solidified to form the pilot hole 23 is 10% of the inner diameter D1 of the pilot hole 23. It is characterized by being ˜40%.

  By suppressing the layer thickness of the solidified portion 23k to 10% to 40% of the inner diameter D1 of the pilot hole 23, the amount of processing in the finishing process, which is a subsequent process, can be reduced, and the processing time can be shortened. it can.

Fourth, the present invention is characterized in that the picosecond laser beam 17 is condensed to be smaller than the inner diameter D1 of the pilot hole 23L, and the inner wall of the pilot hole 23L is removed by evaporation.
If the picosecond laser beam 17 is condensed to be smaller than the inner diameter D1 of the pilot hole 23L, the inner wall of the pilot hole 23L is irradiated to melt and evaporate the inner wall, and a small range is gradually removed to remove the pilot hole The finishing accuracy of the inner wall of 23L can be improved.
Furthermore, since the heat affected zone due to the picosecond laser beam 17 is less likely to occur, the finishing accuracy of the inner wall of the pilot hole 23L can be further improved, and the inner wall of the pilot hole 23L can be made smoother.

Fifth, the present invention is characterized in that the picosecond laser beam 17 is irradiated while being rotated relative to the work 23.
Thereby, the picosecond laser beam 17 can be evenly irradiated to each part of the inner wall of the pilot hole 23L, and the inner wall of the pilot hole 23L can be finished more smoothly. Further, since the picosecond laser beam 17 is not locally irradiated on the inner wall of the pilot hole 23L, the heat affected zone can be made more difficult to occur.

According to the sixth aspect of the present invention, in at least one of the pilot hole machining process and the finishing machining process, the inner wall is melted and evaporated when the nanosecond laser beam 11 or the picosecond laser beam 17 is irradiated to the inner wall. The steam 23p is sucked by a suction device 27 as a steam removing device.
Thereby, the nanosecond laser beam 11 or the picosecond laser beam 17 is not blocked by the vapor, and can be finished satisfactorily.

Seventh, the present invention is characterized in that the peak output of the ultrashort pulse laser oscillator 14 (see FIG. 1) that oscillates the picosecond laser light 17 is 300 kW to 1 MW.
When the output of the ultrashort pulse laser oscillator 14 is less than 300 kW, for example, when the workpiece 23 is made of metal, metal evaporation hardly occurs and much time is required for evaporation removal processing.
When the output of the ultrashort pulse laser oscillator 14 exceeds 1 MW, a heat-affected zone is likely to occur on the inner wall of the prepared hole 23L.

  Therefore, in the present invention, since the output of the ultrashort pulse laser oscillator 14 is set to 300 kW to 1 MW, the inner wall of the pilot hole 23L can be evaporated and removed in a short time, and the heat affected zone is formed on the inner wall of the pilot hole 23L. Can be made difficult to occur.

  Eighthly, the present invention is characterized in that the non-irradiation time T5 in the pulse repetition period T3 of the picosecond laser light 17 is 500 times or more the pulse width T4 in the pulse repetition period T3.

  If the non-irradiation time T5 in the pulse repetition period T3 of the picosecond laser beam 17 is less than 500 times the pulse width T4 in the pulse repetition period T3, the amount of heat input to the work 23 increases, and the pilot hole 23L A heat-affected zone is likely to be generated on the inner wall.

  Therefore, in the present invention, the non-irradiation time T5 of the picosecond laser light 17 is set to 500 times or more of the pulse width T4, so the non-irradiation time T5 of the picosecond laser light 17 can be increased, and the inner wall of the pilot hole 23L The heat-affected zone can be made difficult to occur.

  In the present embodiment, as shown in FIG. 1, the suction device 27 is used as the vapor removing device. However, the present invention is not limited to this, and the vapor removing device blows compressed air to the vapor to pump the vapor. A pumping device that prevents the vapor from blocking the picosecond laser beam may be used.

  The fine hole drilling method of the present invention is suitable for deep hole drilling of members.

It is explanatory drawing of the laser processing apparatus which concerns on this invention. It is an effect | action figure which shows the pilot hole manufacturing process by the laser processing apparatus which concerns on this invention. It is an effect | action figure which shows the finishing process process of the pilot hole by the laser processing apparatus which concerns on this invention. It is a block diagram which shows the laser processing apparatus which enforces the conventional fine processing method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Nanosecond laser beam, 14 ... Laser oscillator (ultrashort pulse laser oscillator), 17 ... Picosecond laser beam, 22 ... Beam rotator, 23 ... Member (workpiece), 23p ... Steam, 23k ... Inner wall (solidification part), 23L ... pilot hole, 27 ... vapor removal device (suction device), D0 ... condensing diameter of nanosecond laser beam, D1 ... inner diameter of pilot hole (inner diameter of solidified portion), T3 ... pulse repetition period of picosecond laser beam, T4: pulse width of picosecond laser beam, T5: non-irradiation time of picosecond laser beam, P2: output of laser oscillator (peak output of ultrashort pulse laser oscillator).

Claims (8)

A pilot hole processing step of piercing a member with nanosecond laser light to open a pilot hole;
A fine drilling method, comprising: finishing the inner wall smoothly by irradiating the inner wall of the prepared hole with a picosecond laser beam.   2. The micro-drilling method according to claim 1, wherein, in the pilot hole machining step, the nanosecond laser beam is irradiated without rotating its optical axis, and the member is evaporated and removed.   In evaporative removal processing in the pilot hole machining step, the layer thickness of the solidified portion that is solidified after being once melted and formed in the pilot hole is 10% to 40% with respect to the inner diameter of the pilot hole. The fine drilling method according to claim 2.   2. The micro-drilling method according to claim 1, wherein the picosecond laser beam is condensed to be smaller than an inner diameter of the pilot hole, and an inner wall of the pilot hole is removed by evaporation.   5. The fine drilling method according to claim 1, wherein in the finishing process, the picosecond laser light is irradiated while being rotated relative to the member.   In at least one of the pilot hole machining step and the finishing machining step, vapor generated by evaporating the inner wall when the inner wall is irradiated with the nanosecond laser beam or the picosecond laser beam is removed by vapor. 6. The micro-drilling method according to claim 4, wherein suction or pressure feeding is performed by an apparatus.   The micro-drilling method according to claim 4, 5, or 6, wherein a peak output of the laser oscillator that oscillates the picosecond laser beam is 300 kW to 1 MW.   8. The non-irradiation time in the pulse repetition period of the picosecond laser beam is 500 times or more of the pulse width in the pulse repetition period. 8. Fine drilling method.

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