TW201741057A - Laser cutting processing method and laser cutting processing apparatus for plated steel sheet - Google Patents

Abstract

Provided is a laser cutting processing method for plated steel sheet, wherein the method generates plasma on the top surface of the laser cutting processing position of plated steel sheet to perform laser cutting processing when causing a part of plating material that is melted and/or evaporated by irradiation of laser light LB, to the cutting surface of the plated steel sheet W by assist gas ejected to laser processing portion, to coat the cutting surface with the plating material during performing lase cutting processing by irradiating laser light LB on the top surface of the plated steel sheet W.

Description

Laser cutting processing method for plated steel plate and laser cutting processing device

The laser cutting processing method and the laser cutting processing device for a plated steel sheet according to the present invention, in detail, when laser cutting processing for a plated steel sheet is performed, it is melted by irradiation of laser light and/or One part of the plating of the evaporated surface flows (guides) to the cut surface by the assist gas, and when the cut surface is covered by the molten metal which is melted and/or evaporated, plasma is generated to perform laser cutting Laser cutting processing method and laser cutting processing device for cutting processing.

In the past, when a workpiece such as a plated steel sheet is cut, the laser cutting of the workpiece is performed after the surface of the workpiece is removed (see, for example, Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 7-236984

According to the configuration described in the above Patent Document 1, after the laser cutting process is performed after the plating of the workpiece surface is removed, there is a problem in the efficiency of the laser cutting process for lifting the workpiece. Further, according to the configuration described in Patent Document 1, since the cut surface subjected to the laser cutting has no surface to be coated with plating, it is necessary to use a problem of appropriate surface treatment such as rustproof treatment.

The present invention has been made in view of the above problems, and is a laser cutting processing method for a plated steel sheet, which is a laser beam when a laser beam is irradiated onto a surface of a plated steel sheet to perform laser cutting processing. One part of the plated metal on the surface that is melted and/or evaporated by irradiation is guided to the cut surface side of the plated steel sheet by the auxiliary gas sprayed from the laser processed portion, and is cut on the cut surface When the metal plating is applied, plasma is generated on the upper surface of the laser cutting portion of the plated steel sheet to perform laser cutting processing.

Further, in the laser cutting method of the plated steel sheet, the laser beam is irradiated with the laser light which is heated and evaporated by the irradiation of the laser light on the upper surface of the plated steel sheet to generate plasma.

Further, in the laser cutting method of the plated steel sheet, the focus position of the laser light is adjusted within a range of +0.5 mm to -4.5 mm.

Moreover, in the laser cutting processing method of the plated steel sheet, the nozzle gap between the nozzle of the laser processing head and the upper surface of the plated steel sheet is adjusted within a range of 0.3 mm to 1.0 mm, and the auxiliary gas is used. The pressure is adjusted in the range of 0.5 MPa to 1.2 MPa.

Further, in the laser cutting processing method for the plated steel sheet, the laser cutting processing speed is adjusted in the range of 1000 mm/min to 5000 mm/min.

Further, in the laser cutting method of the plated steel sheet, the nozzle for discharging the assist gas has a diameter of 2.0 mm to 7.0 mm.

Further, the laser cutting apparatus of the present invention includes: a workpiece workpiece stage that supports a plate-shaped workpiece; and a laser processing head that can relatively freely determine a moving position in the X, Y, and Z axis directions of the workpiece; a control device for controlling the action of the aforementioned laser processing head; The control device includes a cutting condition data table in which a laser cutting processing condition is stored for each of the plated steel sheets and a plating thickness, and the laser cutting processing conditions are performed on the workpiece table. When the steel sheet is irradiated with laser light to perform laser cutting, one part of the plated metal to be melted and/or evaporated by the irradiation of the laser light is applied to the steel sheet by the auxiliary gas sprayed from the laser processing unit. The cut surface side is guided, and the plated metal is coated on the cut surface.

1‧‧‧Laser cutting and processing device

3‧‧‧Working table

5‧‧‧Laser processing head

7‧‧‧ Positioning motor

9‧‧‧Z-axis motor

11‧‧‧Laser oscillator

13‧‧‧Mirror

15‧‧‧ Concentrating lens

17‧‧‧Optical device

19‧‧‧ nozzle

21‧‧‧Auxiliary gas supply device

23‧‧‧Nitrogen supply device

25‧‧‧Oxygen supply device

27‧‧‧ Mixer

29‧‧‧Pressure regulator

31‧‧‧Control device

33‧‧‧Several Conditions Data Sheet

35‧‧‧ Input means

W‧‧‧ plated steel

LB‧‧‧illuminated laser light

M‧‧‧ plating layer

Fig. 1 is a schematic explanatory view showing the configuration of a laser cutting apparatus according to an embodiment of the present invention in a conceptual and schematic manner.

Fig. 2 is a result of EMPA analysis of the cut surface at the time of oxygen cutting, clean cutting, and simple cutting.

Fig. 3 (A) to (C) show enlarged photographs of the cut surface at the time of clean cutting, oxygen cutting, and simple cutting.

Fig. 4 is an enlarged photograph showing the state of coating of the metal containing the plating layer on the cut surface when the laser cutting processing conditions are changed.

Fig. 5 is an enlarged photograph showing the state of the coating of the metal containing the plating layer on the cut surface when the laser cutting processing conditions are changed.

Fig. 6 is an enlarged photograph showing the state of coating of the metal containing the plating layer on the cut surface when the laser cutting processing conditions are changed.

Fig. 7 is an enlarged photograph showing the state of coating of the metal containing the plating layer on the cut surface when the laser cutting processing conditions are changed.

Fig. 8 is a photograph showing the state of generation of plasma.

Fig. 9 is an enlarged photograph showing the results of evaluation of the corrosion resistance of the cut surface.

Fig. 10 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 11 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 12 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 13 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 14 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 15 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 16 (A) to (D) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 17 (A) to (C) are explanatory diagrams and photographs showing the evaluation results at the time of plasma generation and exposure test.

Fig. 18 is an explanatory view showing the relationship between the occurrence of plasma at the time of clean cutting and simple cutting and the occurrence of rust in the exposure test.

Fig. 19 is a photograph showing the difference between the EDS analysis result and the occurrence of rust caused by the difference in processing speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the first embodiment, a configuration of a laser cutting apparatus according to an embodiment of the present invention is conceptually and conceptually shown.

Referring to Fig. 1, a laser cutting apparatus 1 according to an embodiment of the present invention is provided with a workpiece table 3 that supports a plate-shaped workpiece W, and is provided to irradiate the workpiece W with laser light LB. The laser processing head 5 of the laser cutting process of the workpiece W. The workpiece table 3 is provided to the laser processing head 5 so as to be relatively movable in the X and Y axis directions, and is provided to move the workpiece table 3 relative to each other in the X and Y axis directions. A positioning motor 7 like a servo motor. Further, a Z-axis motor 9 that moves and positions the laser processing head 5 in a direction in which the workpiece W is relatively moved away from the direction (Z-axis direction) is provided.

Further, the laser cutting apparatus 1 includes a laser oscillator 11 such as a fiber laser oscillator or a CO ₂ laser oscillator. Further, the processing head 5 includes an optical mirror 13 that reflects the laser beam LB oscillated by the laser oscillator 11 in the direction of the workpiece W, or an optical lens that condenses the laser beam LB. Device 17. Further, in the laser processing head 5, the nozzle 19 for discharging the assist gas by the laser cutting device having the laser beam W to the workpiece W is detachably exchangeable.

On the other hand, in the configuration in which the auxiliary gas is ejected to the laser cutting processing portion, the laser processing head 5 may be provided with a side nozzle, and the auxiliary gas may be ejected toward the laser processing unit from the side nozzle. .

Further, the laser cutting apparatus 1 includes an assist gas supply device 21. The auxiliary gas supply device 21 supplies a mixed gas of, for example, about 97% of nitrogen gas and about 3% of oxygen, and includes a nitrogen gas supply device 23, an oxygen supply source (air supply source) 25, and a mixer 27 that generates a mixed gas. Further, the assist gas supply device 21 is provided with a pressure regulating valve 29 for adjusting the pressure of supplying the assist gas to the laser processing head 5. Further, when the oxygen supply source 25 of the assist gas supply device 21 is stopped and only the nitrogen gas supply device 23 is operated, the auxiliary gas which is only nitrogen gas can be supplied to the processing portion.

The configuration in which the mixed gas having a nitrogen gas content of about 97% and an oxygen gas of about 3% is supplied as an assist gas to the laser processing unit is not limited to the above configuration, and may be configured separately. That is, for example, as described in Japanese Patent No. 3291125, nitrogen gas and oxygen gas in the supplied compressed air can be separated by the separation device of the hollow fiber membrane. Further, a mixed gas of about 97% (96% or more) of nitrogen gas and about 3% (4% or less of oxygen) is used as a laser cutting process for the assist gas, and hereinafter simply referred to as simple cutting.

Moreover, the laser cutting apparatus 1 is provided with the control apparatus 31. The control device 31 is constituted by a computer, and has a function of controlling the relative movement of the laser processing head 5 of the workpiece W, and a laser output controlled by the laser oscillator 11. The function of controlling and supplying pressure to the assist gas of the aforementioned laser processing head 5.

According to the above configuration, after the workpiece W is placed on the workpiece table 3, the laser processing head 5 is relatively moved and positioned in the X, Y, and Z-axis directions with respect to the workpiece W. Further, the laser beam LB oscillated from the laser oscillator 11 is condensed by the condensing lens 15 to be irradiated onto the workpiece W. Further, the auxiliary gas supplied from the assist gas supply device 21 to the laser processing head 15 is ejected from the nozzle 19 to the laser processing portion of the workpiece W, whereby the laser cutting process of the workpiece W is performed.

In the case of performing the laser cutting process of the workpiece W, the workpiece W is a plated steel sheet. As described in the 21st of the above-mentioned Patent Document 1, the evaporation material of the plating layer may enter the processing range. And the processing quality has defects. Therefore, in the description of Patent Document 1, as shown in Fig. 1 of Patent Document 1, the surface of the plated steel sheet is irradiated with laser light to remove the plating layer in advance. Then, the laser cutting processor of the same trajectory is implemented next.

According to the above configuration, since there is no evaporation of the plating during the laser cutting process, the processing quality can be improved, but the laser processing of the plating layer removal and the cutting process must be performed twice. Moreover, since the cut surface of the plated steel sheet is still subjected to laser cutting processing State, there is a problem that it is necessary to cut off the surface of the rust-proof treatment.

In the embodiment of the present invention, it is found that during the laser cutting process of the plated steel sheet, the plating and/or evaporation of the plating layer on the upper surface of the plated steel sheet can be melted and/or evaporated. The metal of the layer flows toward the cut surface, and the cut surface is covered by the flowing metal containing the plating layer.

In the embodiment of the present invention, as an example of the plated steel sheet, a molten plated steel sheet in which a plating layer of 6% of aluminum, 3% of magnesium, and 91% of zinc is coated on the surface of the steel sheet (hereinafter referred to as plating) is used. Steel plate).

Further, oxygen cutting which is generally performed in laser cutting processing uses oxygen as an auxiliary gas. Then, an analysis of an EPMA (Electron Probe Micro Analyzer) for cutting the processed surface was carried out, and as a result of the oxygen cut, as shown in Fig. 2, the cut surface was covered with an oxide film. Therefore, it can be seen that when laser cutting of a plated steel sheet is performed, if it is intended to be coated with a metal containing a plating layer which is melted or evaporated, the oxygen cutting system is not suitable for laser cutting processing of the plated steel sheet. .

Next, in the case of performing a laser cutting processing method using nitrogen gas as an auxiliary gas (hereinafter, simply referred to as clean cutting), depending on the cutting conditions, as shown in the enlarged photograph of FIG. 3(A), plating is performed. The laser cutting process of the cut surface CF of the base material B of the steel sheet is performed satisfactorily. Further, the plating layer M on the upper surface in the vicinity of the upper end portion of the cut surface CF is removed to be extremely thin. Further, there is no oxide film or the like on the cut surface CF, and almost all of the original plate component (Fe) of the plated steel sheet is exhibited (see FIG. 2). Moreover, the coating layer (plating surface) of the cut surface CF is also extremely thin. Therefore, in a clean cut In the middle of the break, the cut surface CF can be covered by the molten metal containing the plating by appropriate cutting conditions, and rust (rust) may not be generated.

Next, as in the case of performing the simple cutting described above, as shown in Fig. 2 and Fig. 3(C), a thin oxide film is formed on the cut surface. Further, zinc, aluminum, and magnesium which are components of the plating layer M are formed on the upper portion of the cut surface. That is, a part of the molten plating layer in the vicinity of the upper end portion of the cut surface CF flows into the cut surface CF, and the concentrated portion of the molten plating layer appears in a white stripe shape. Further, a molten plating layer exists thinly between the stripe-shaped portions.

In other words, it has been found that the laser cutting process of the steel sheet is generally performed by a clean cutting or a simple cutting, whereby the metal containing the plating layer M is wound into the plated steel sheet (workpiece) W. By cutting the surface, the cut surface CF can be covered.

Then, various processing conditions such as the cutting speed at the time of laser processing, the focus position of the condensing lens, the gas pressure of the assist gas, and the frequency of the pulse of the laser light are variously changed, and the test is performed on the plated layer of the cut surface. Coverage status. Further, the test conditions are as follows.

Laser cutting machine: Amada (share) company, FOM2-3015R1

Material: plated steel plate coated with 6% of aluminum, 3% of magnesium and 91% of residual zinc on the surface, plate thickness t=2.3mm, K35 (one-side plating metal adhesion 175g/m ² )

Cut sample shape: 130mm × 30mm

Standard processing conditions

‧Nozzle diameter: D4.0 (4.0mm)

‧ Cutting speed: F1600 (1600mm/min)

‧Auxiliary gas type: EZ (indicates the auxiliary gas used for the simple cut-off described above. The auxiliary gas at this time is a mixed gas of about 97% nitrogen and 3% oxygen)

‧Auxiliary gas pressure: 0.9MPa

‧ Nozzle gap: 0.3mm (the gap between the nozzle and the plated steel plate)

‧ Focus position: -4.5mm (Set the upper side as + with the top of the workpiece as 0 and the lower side as -)

The results of processing by changing the conditions of the above standard processing conditions are as follows.

As can be seen from Fig. 4, when the cutting speed is adjusted in the range of 1120 mm/min to 3840 mm/min, the coating amount of the plated metal on the cut surface (cut end surface) is increased, and the amount of coating is gradually increased.

As can be seen from Fig. 5, when the focus position of the condensing lens is adjusted in the range of -6.5 mm to +0.5 mm, and the focus position is gradually set to the + side, the coating amount of the plated metal on the cut surface is gradually increased. .

As shown in Fig. 6, when the assist gas pressure is adjusted in the range of 0.5 MPa to 0.9 MPa, the lower the assist gas pressure, the more the coating coverage of the cut end face is gradually increased.

As shown in Fig. 7, when the pulse frequency of the laser light was adjusted in the range of 800 Hz to CW (continuous), the amount of coating of the plated metal on the cut end face did not show a large change.

As can be seen from the results shown in Figures 4 to 7, In the cutting, the coating amount of the metal containing the plating layer on the laser cut surface of the plated steel sheet is increased as the cutting speed is increased (for example, 3840 mm/min). Further, the focus position is on the + side (for example, +0.5 mm), and the amount of metal containing the plating layer is increased. However, when the focus position is increased on the (+) side, since the energy density on the upper surface of the plated steel sheet is lowered, it is preferable to set it to the side in the laser cutting process. Further, the lower the auxiliary gas pressure (for example, 0.5 MPa), the more the coating amount of the metal containing the plating layer. Further, when the laser light is adjusted to a pulsed laser or a continuous laser, the amount of coating of the plated metal does not show a large change.

As is understood, in the laser cutting process of a plated steel sheet, when the laser cutting process of the plated steel sheet is performed by simple cutting, for example, the laser cutting process conditions are cut off. Various changes such as the speed, the focus position of the condensing lens, and the assist gas pressure change the amount of coating of the metal containing the plating layer on the laser cut surface of the plated steel sheet. Further, in terms of laser cutting processing conditions, it is also conceivable to change the interval between the nozzle 19 of the laser processing head and the upper surface of the workpiece W, that is, the nozzle gap.

That is, it has been found that the coating amount of the metal containing the plating layer on the laser cut surface varies depending on the processing conditions at the time of laser cutting processing of the plated steel sheet. In other words, when the laser cutting conditions of the plated steel sheet are appropriately cut, the metal containing the plating layer is appropriately covered on the laser cut surface.

According to the simple cutting, it was found that the cut surface of the plated steel sheet can be covered by the metal containing the plating layer.

Secondly, in order to find the appropriate cut strips when clean cutting The laser cutting process of the plated steel sheet was carried out by various cutting conditions, and an exposure test was performed to observe the state of occurrence of rust on the laser cut surface. In the exposure test, the cut surface of the laser cut processed product subjected to the laser cutting process of the plated steel sheet was held on the top and placed in the field for one month.

When the laser cut product is cut and separated from the plated steel sheet by clean cutting, as shown in Fig. 8, there is a case where plasma is generated on the laser cutting processing position, and it does not occur. situation. Further, even in the case where plasma is generated, the state of generation of weak plasma and generation of strong plasma (not weak plasma) can be distinguished by visual observation. Then, it is set to "none" in the case where no plasma is generated, "p" in the case where weak plasma is generated, and "P" in the case where strong plasma is generated. In addition, if the cutting condition is unsuitable and the laser cutting process cannot be performed, it is set to "No".

Further, in the one-month exposure test, as shown in Fig. 9, "○" is set in the case where no rust occurs, and "x" is set in the case where rust is generated. Here, the aforementioned exposure test is a result of one month in the field. Therefore, in the laser cut processed product, even if it is evaluated as "X", depending on the environment used, it is still possible to use it.

Next, a clean cut using nitrogen gas as an auxiliary gas is carried out, and the result of the exposure test of the plated steel sheet having a thickness t=2.3 mm, t=3.2 mm, t=4.5 mm, and t=6.0 mm is performed as described above. 10 to 17 shown. In Figs. 10 to 17 , K14, K27, and K35 are indications of the adhesion amount of the plated metal, respectively, and the respective plating metal adhesion amounts are as follows. That is, K14 (one-side plating metal adhesion amount: 70 g/m ² ), K27 (one-side plating metal adhesion amount: 145 g/m ² ), and K35 (one-side plating metal adhesion amount: 175 g/m ² ).

Further, in Figs. 10 to 17, S denotes a single nozzle, and D denotes a double nozzle. A double nozzle system is known as disclosed in Japanese Laid-Open Patent Publication No. Hei 11-90672. Further, S2.0, D4.0, and D7.0 represent the nozzle diameter (mm), respectively. That is, S2.0 = 2.0 mm, D4.0 = 4.0 mm, and D7.0 = 7.0 mm. Further, the nozzle gap corresponding to each nozzle was set to 0.3 mm at S2.0, 0.5 mm at D4.0, and 1.0 mm at D7.0. That is, when the diameter of the nozzle is increased, splashes or the like generated at the laser processing position are easily entered into the nozzle, so that the larger the nozzle diameter, the larger the nozzle gap is set.

Further, the parameters of the laser processing other than the parameters specifically described are those having the same values as those of the standard processing conditions described above.

Furthermore, as shown in FIG. 10, in the case where the focus position is -0.5 mm (the focus position is shown in each drawing), the plate thickness is t = 2.3 mm, and the plating metal adhesion amount K14 is applied, the nozzle diameter S2.0 is In the case, at 1000 mm/min, the auxiliary gas pressure does not occur in the plasma at 0.9 MPa, 0.7 MPa, and 0.5 MPa. Then, the evaluations in the exposure test were all "x", which produced rust comprehensively. Further, as shown in Fig. 11, Fig. 12, Fig. 13, Fig. 14, and Fig. 15, the cutting speed is 1000 mm/min, and in the nozzle having the nozzle diameter S2.0, there is no auxiliary gas pressure. There is no plasma. Also, the evaluation of the exposure test is "X", and the prevention of the cut surface The rust effect is not worth expecting.

Therefore, when the nozzle having a nozzle diameter of 2.0 is used and the laser cutting process of the plated steel sheet is performed at a cutting speed of 1000 mm/min, the metal containing the plating layer which is melted and/or evaporated during the laser cutting process is The cut surface flows, and it is difficult to cover the cut surface.

Next, in the case of Fig. 10, Fig. 11, and Fig. 12, the case of the nozzle diameter D4.0 was investigated. In Figs. 10 and 11, there was no occurrence of plasma, and the evaluation of the exposure test was "x". However, when the assist gas pressure is 0.7 MPa in Fig. 11, the improvement is "○". Also, in the case of the nozzle diameter D7.0, there is a weak plasma. The evaluation of the exposure test is "X" in Figure 10, but it is "○" and "X" in Figure 11. Then, in the 12th figure, it is "X".

In the figures from Fig. 10 to Fig. 17, when the evaluation of the exposure test is "○" or "X", there is a case where plasma is generated (P), and it is almost "○". Therefore, when the laser cutting of the plated steel sheet is performed by clean cutting, the molten and/or evaporated metal containing the plating layer flows toward the cut surface, and the cut surface is melted and/or The evaporated metal containing the plating layer is covered, and it is desirable to perform the laser cutting process while generating plasma.

As can be seen from Fig. 11, in the case of the plating metal adhesion amount K27 and the nozzle diameter D4.0, although no plasma occurred, the evaluation of the exposure test was "○". Further, in the nozzle diameter D7.0 and the assist gas pressure of 0.9 MPa in Fig. 10, although slight plasma generation occurred, the above evaluation was "x".

Further, in Fig. 10, Fig. 11, and Fig. 12, the cutting speed is in the range of 3000 mm/min to 5000 mm/min, and the occurrence of plasma can be seen in all of them, and the result of the observation is The faster the cutting speed, the stronger the plasma is. Further, the above evaluations in the entire range except the nozzle diameter S2.0, the assist gas pressure of 0.9 MPa, and the 0.7 MPa (3000 mm/min) in Fig. 10 are all "○". In addition, in Fig. 10, the nozzle diameter is 2.0 mm, and the assist gas pressure is 0.7 MPa from 4000 mm/min to 5000 mm/min, which is "○".

Therefore, in order to make the evaluation of the exposure test "○", in the case where the plate thickness of the plated steel sheet is t = 2.3 mm, and the plating metal adhesion amount K14 is the nozzle diameter S2.0, it is preferable that the auxiliary gas pressure is 0.7 MPa. And the cutting speed is in the range of 4000 mm/min to 5000 mm/min. Further, in the case where the assist gas pressure is 0.5 MPa, it is preferably in the range of 3000 mm/min to 5000 mm/min. In the case where the nozzle diameter is D4.0 or D7.0, the assist gas pressure is not limited to 0.9 MPa, 0.7 MPa, 0.5 MPa, and preferably the cutting speed is in the range of 3000 mm/min to 5000 mm/min.

As shown in Fig. 11, in the case where the plated steel sheet is the same plate (t = 2.3 mm), when the amount of plating metal is K27 and increases (thickened), the nozzle diameter D4.0 and the assist gas pressure are 0.7 MPa. At the cutting speed of 1000 mm/min, although no plasma occurred, the evaluation was "○". Therefore, if the plated steel plate has a plate thickness (t=2.3 mm), a plated metal adhesion amount K27, a nozzle diameter D4.0, an assist gas pressure of 0.7 MPa, and a cutting speed of 1000 mm/min, the conditions are appropriately adjusted, even if not The plasma is generated and the evaluation can be set to "○". In other words, when the above conditions are met, In the case where the electric paddle is not generated, the metal containing the plating layer which is melted and/or evaporated during the laser cutting process may flow on the cut surface and cover the cut surface.

Next, referring to Fig. 12, although only the plating metal adhesion amount is changed to K35, the cutting speed is 1000 mm/min, the nozzle diameter D4.0, the assist gas pressure 0.7 MPa, the nozzle diameter D0.7, and the assist gas. Under the conditions of a pressure of 0.9 MPa and 0.7 MPa, although a slight plasma generation was observed, the evaluation was "x".

In general, when laser cutting is performed on a metal plate, if plasma is generated, the plasma has the property of absorbing laser light, and the irradiation of the laser light promotes the generation of continuous plasma. Further, it is known that the plasma system deteriorates the roughness of the cut surface. However, for example, in the case of non-oxidative cutting of stainless steel, there is a plasma cutting method using heat of plasma. In this case, the processing conditions are set in such a manner as to promote the generated plasma.

That is, in the above case, (i) the auxiliary gas system is set to a low pressure. (ii) The nozzle gap between the nozzle and the workpiece is a space for forming plasma to grow, which is slightly larger than usual. (iii) The amount of driving in the focus position is set to the (+) direction above the workpiece surface, and is set to the (-) direction lower than the workpiece surface, which is more toward the normal focus position (+ ) Move in the direction. (iv) In order to reduce the heat input of the laser light toward the workpiece, the cutting speed is made higher. The conditions (i) to (iv) described above are conditions in which plasma is likely to occur when laser cutting of a metal plate is performed.

If the above conditions (i) to (iv) are considered and the figure 10 is viewed, in the plating metal adhesion amount K14, the cutting speed is in the range of 1000 mm/min to 2000 mm/min, and the plasma generation nozzle diameter is D4.0 More than S2.0, more people in D7.0 than D4.0. Moreover, the cutting speed is gradually increased from 1000 mm/min to 5000 mm/min, and the generation of plasma is enhanced. Then, when the generation of the plasma becomes strong, the result of the exposure test is increased by "○". Furthermore, even in the 11th and 12th figures, the same tendency can be seen.

Therefore, in the laser cutting process of the plated steel sheet, the molten metal containing the plating layer on the upper surface is caused to flow toward the cut surface, and the cut surface is covered by the part of the plated metal. It is preferred to produce a plasma.

Fig. 13, Fig. 14 and Fig. 15 are the cases of clean cutting, and the plate thickness of the plated steel plate is t=3.2 mm, and the amount of plating metal adhesion is the exposure test in the case of K14, K27, K35. result. Furthermore, in the 13th to 14th drawings, "no" indicates that it is impossible to cut off. That is, the cutting condition is not suitable. The results from Fig. 13 to Fig. 15 are also apparent, and it is understood that the assist gas pressure is low, and those having a faster cutting speed tend to have less tendency to generate plasma.

Fig. 16 and Fig. 17 are the cases of clean cutting, and the results of the exposure test in the case of the plate thickness t = 4.5 mm, t = 6.0 mm, even in this case, the auxiliary gas pressure is lower, in other words The larger the diameter of the nozzle, the faster the cutting speed and the stronger the generation of plasma. Further, the stronger the generation of the plasma, the more the result of the exposure test becomes "○". Further, in the sixteenth and seventeenthth drawings, "d" indicates that the amount of dross attached is large.

The knot of the exposure test shown in the above 10th to 17th The result is stored in the cutting condition data table 33 included in the control device 31 of the laser cutting apparatus 1 described above. That is, in the above-described cutting condition data table 33, the thickness of each of the plated steel sheets is applied, and the diameter of the nozzle to which the amount of plating metal is applied to each of the plate thicknesses is the nozzle gap of each nozzle diameter. Applicable to the focus position of each plate thickness, as well as the processing conditions of the cutting speed. Further, in the cutting condition data table 33, the data generated by the plasma during the laser cutting process of the plated steel sheet and the evaluation results of the exposure test are stored. Further, the control device 31 also includes a cutting condition data sheet in which processing conditions at the time of simple cutting are stored.

Therefore, when various processing conditions are input from the input means 35 connected to the control device 31, the laser cutting process which can obtain the same evaluation as the evaluation shown in Figs. 10 to 17 is carried out. In other words, for example, in the plate thickness t=2.3 mm shown in FIG. 10, the conditions of the plating metal adhesion amount K14, the nozzle diameter D4.0, the assist gas pressure 0.7 MPa, and the cutting speed 5000 mm/min are input from the input means. When 35 is input to the control device 31 and laser cutting is performed, a plasma is generated and a laser cutting process is performed. Also, if a one-month exposure test is carried out, the evaluation can obtain "○".

Further, when the exposure test is carried out, the changer is sometimes evaluated depending on the environment or weather conditions such as the vicinity of the sea.

In order to perform laser cutting of the plated steel sheet, the melted and/or evaporated metal containing the plating layer flows on the cut surface, and when the cut surface is covered, the melting range of the plated metal is regarded as the sheet of the workpiece. Depending on the thickness of the plated metal and the laser cutting bar, it is only from the cut end of the workpiece. A range of 0.03 mm to 0.5 mm is preferred.

That is, when the range in which the plating layer is melted and/or evaporated is 0.5 mm or more, the laser cutting speed is slow, and the amount of heat input is large. In this case, it is considered that the amount of plating metal which is melted and/or evaporated is increased, and the amount of inflow into the laser cutting groove is increased. However, since the laser cutting speed is slow, the irradiation time of the laser light is long, the heating time becomes long, and the molten and/or evaporated metal containing the plating layer is kept at a high temperature for a long time, and the auxiliary gas acts. The time becomes long, and it is easy to be blown off by the assist gas before adhering to the cut surface and solidified, and the amount of the metal containing the plating layer which is melted and/or evaporated on the cut surface is reduced (for example, refer to FIG. 12 D4.0, D7.0).

However, when the melting and/or evaporation range of the plating layer is in a small range of 0.03 mm, the laser cutting speed is fast, and the amount of heat input is small. In this case, it is considered that the amount of melting and/or evaporation is reduced, and the amount of heat input to the laser cut surface is reduced.

Therefore, the melting and/or evaporation range of the plating layer is preferably in the range of 0.03 mm to 0.5 mm from the cut surface. In the above range, the irradiation time of the laser light and the time of the auxiliary gas action become appropriate time, and the amount of the molten metal which is melted and/or evaporated is reduced by the assist gas. Therefore, it is considered that the solidified surface is easily covered by the cut surface, and the amount of the metal containing the plating layer is increased (for example, refer to D4.0 and D7.0 in Fig. 12).

As is known, in the laser cutting process of a plated steel plate, a clean cut using nitrogen as an auxiliary gas or nitrogen is used. When a mixed gas of about 97% and about 3% of oxygen is simply cut off as an assist gas, the cut surface may be coated with the metal containing the plating layer. Further, if plasma is generated during the laser cutting process, it is found that the above coating can be effectively performed.

Then, the clean cut and the simple cut of the plated steel sheet having the thickness t=2.3 mm, the plasma generation, and the exposure test one month later were carried out, and the results as shown in Fig. 18 were obtained. From the results shown in Fig. 18, it can be seen that both the net cutting and the simple cutting can generate the plasma while performing the laser cutting, and the cut surface can be effectively made by the metal containing the plating layer. The ground is covered and can prevent the occurrence of rust.

Further, the faster the processing speed, the more effectively the coating of the cut surface of the metal containing the plating layer can be effectively prevented, and the occurrence of rust can be prevented. Then, the observation result of the cut surface at the time of laser cutting of the plated metal adhesion amount K14 at a processing speed of 2200 mm/min and 5000 mm/min is shown in Fig. 19 .

As can be seen from Fig. 19, the case where the processing speed is 2200 mm/min is the occurrence of rust. However, when the processing speed is 5000 mm/min, the metal component containing the plating layer can be completely detected on the cut surface, and the occurrence of rust is not observed. This result is consistent with the results shown in Figure 18.

From the analysis results of the EDS (Energy Dispersive X-ray Spectrometry) and the exposure test results (after 4 weeks) of the laser cut surface shown in Fig. 19, the following items were known. At the time of clean cutting in Fig. 2, a very small amount of metal containing a plating layer was examined from the laser cut surface. Therefore, the processing speed which is slightly equivalent to the clean cutting condition of Fig. 2 is 2200 mm/min. When the laser cut surface was subjected to EDS analysis, it was found that the Zn (zinc), Al (aluminum), and Mg (magnesium) components, that is, the metal containing the plating layer were extremely small, and the amount of photodetection was less than or equal to that of the photographing image. The laser cut surface is uncovered on the metal containing the plating layer. In addition, as shown in the photograph of the EDS analysis result of the processing speed of 5000 mm/min as shown in Fig. 19, it is known that the plated metal is detected in the entire area of the laser cut surface, and the laser is detected. The entire area of the cut surface is covered with a metal containing a plating layer. That is, according to the cut surface of the standard condition (machining speed: 2200 mm/min), the iron content is about 90% (weight % of Fe: 89.16), and the metal components of the plating (Zn, Al, and Mg are all at Weight %: 1.45 or less) was hardly detected. Therefore, rust is easily generated. On the other hand, when cutting is performed according to the current processing conditions (processing speed: 5000 mm/min), the iron content of the cut surface is greatly reduced to about 30% (weight % of Fe: 32.48), and instead, the Zn system is greatly reduced. Increasing to % by weight: 43.57, even if it is increased by several times or more in Al and Mg, it is understood that the plating component covers the entire cut surface and covers the surface thereof. Therefore, it is understood that the person who suppresses the occurrence of rust flows from the top during the laser cutting process, and is a plated metal component covering the surface of the cut surface.

As can be understood from the above description of the embodiment, the laser cutting process is performed under appropriate processing conditions in accordance with the thickness of the plated steel sheet and the amount of deposited metal, and the melting is performed on the upper surface during the electric cutting. And/or the evaporated metal containing the plating layer flows to the cut surface, and the cut surface is easily covered. Therefore, the thickness of the plating layer in the vicinity of the upper edge of the cut surface of the plated steel sheet is smaller than the portion away from the cut surface, that is, it is not subjected to melting and/or evaporation at the time of laser cutting. Metal flow of the plating layer The thickness of the plating layer at the portion of the thermal influence of the moving degree is thinner.

In the foregoing description, the case of a plated steel sheet of 6% aluminum, 3% magnesium, and 91% of the remaining zinc is exemplified. However, the plated steel sheet is not limited to the above-described plated steel sheet, and may be applied to other cases of plated steel sheets.

Further, in the laser cutting processing method of the plated steel sheet, the plate thickness is preferably 2.3 mm, the plating metal adhesion amount is K14, the nozzle diameter is 2.0 mm to 7.0 mm, and the assist gas pressure is 0.5 to 0.9 ( MPa), the cutting speed is 3000 to 5000 (mm/min).

Further, in the laser cutting processing method for a plated steel sheet, the thickness of the plate is preferably 2.3 mm, the amount of plating metal is K27 or K35, the diameter of the nozzle is 2.0 mm to 7.0 mm, and the pressure of the auxiliary gas is 0.5 to 0.9. (MPa), the cutting speed is 3000 to 5000 (mm/min).

Further, in the laser cutting method for a plated steel sheet, the thickness of the plate is preferably 3.2 mm, the amount of plating metal is K27 or K35, the diameter of the nozzle is 7.0 mm, and the pressure of the auxiliary gas is 0.5 to 0.9 (MPa). The cutting speed is 2000 to 3000 (mm/min).

Further, in the laser cutting method for a plated steel sheet, the thickness of the plate is 4.5 mm, the amount of plating metal is K27 or K35, the diameter of the nozzle is 7.0 mm, and the pressure of the assist gas is 0.7 to 0.9 (MPa). The cutting speed is 1500 to 2000 (mm/min).

[Industrial availability]

According to the present invention, the laser cutting process can be performed without removing the plating of the plated steel sheet. Further, when performing laser cutting of the plated steel sheet, one part of the plated metal which is melted and/or evaporated may be used. It flows (guides) on the cut surface, and covers the cut surface. Therefore, it is possible to efficiently perform the laser cutting process of the plated steel sheet, and it is not necessary to perform the rustproof treatment of the cut surface after the laser cutting process.

1‧‧‧Laser cutting and processing device

3‧‧‧Working table

5‧‧‧Laser processing head

7‧‧‧ Positioning motor

9‧‧‧Z-axis motor

11‧‧‧Laser oscillator

13‧‧‧Mirror

15‧‧‧ Concentrating lens

17‧‧‧Optical device

19‧‧‧ nozzle

21‧‧‧Auxiliary gas supply device

23‧‧‧Nitrogen supply device

25‧‧‧Oxygen supply device

27‧‧‧ Mixer

29‧‧‧Pressure regulator

31‧‧‧Control device

33‧‧‧Several Conditions Data Sheet

35‧‧‧ Input means

W‧‧‧ plated steel

LB‧‧‧illuminated laser light

M‧‧‧ plating layer

Claims (8)

A laser cutting processing method for a plated steel sheet, which is a metal plated metal that is melted and/or evaporated by irradiation of laser light when the upper surface of the plated steel sheet is irradiated with laser light to perform laser cutting processing. A part of the laser beam is irradiated on the cut surface side of the plated steel sheet by the auxiliary gas discharged from the laser processing unit, and the plated metal is coated on the cut surface to provide a laser beam on the plated steel sheet. A plasma is generated on the upper surface of the cut processing portion to perform laser cutting processing. The laser cutting processing method of the plated steel sheet according to the first aspect of the invention, wherein the vaporizing of the plated metal heated by evaporation of the laser light on the upper surface of the plated steel sheet is irradiated Laser light to produce plasma. The laser cutting processing method for a plated steel sheet according to the first or second aspect of the invention, wherein the focus position of the laser light is adjusted within a range of +0.5 mm to -4.5 mm. The laser cutting processing method for a plated steel sheet according to any one of the preceding claims, wherein the nozzle gap between the nozzle of the laser processing head and the upper surface of the plated steel sheet is The adjustment is carried out in the range of 0.3 mm to 1.0 mm, and the assist gas pressure is adjusted in the range of 0.5 MPa to 1.2 MPa. The laser cutting processing method for a plated steel sheet according to any one of the preceding claims, wherein the laser cutting processing speed is in a range of from 1000 mm/min to 5000 mm/min. Adjustment. Plating as described in any one of claims 1 to 5 In the electric radiation cutting method of a steel sheet, the nozzle for discharging the assist gas has a diameter of 2.0 mm to 7.0 mm. The laser cutting processing method for a plated steel sheet according to any one of the preceding claims, wherein the auxiliary gas system is a mixed gas of nitrogen gas or nitrogen gas of 97% and oxygen gas of 3%. A laser cutting processing apparatus comprising: a workpiece table that supports a plate-shaped workpiece; a laser processing head that can relatively freely determine a moving position in the X, Y, and Z-axis directions of the workpiece, and is used for controlling a control device for operating the laser processing head; the control device includes a cutting condition data table in which a laser cutting processing condition is stored for each of the plated steel sheets and a plating thickness, and the laser cutting processing is performed The condition is that when a plated steel plate on the workpiece table is irradiated with laser light to perform laser cutting, one part of the plated metal to be melted and/or evaporated by the irradiation of the laser light is used by the thunder The assist gas discharged from the shot processing unit is guided to the cut surface side of the steel sheet, and the plated metal is coated on the cut surface.