JP6512685B2 - Laser cutting method - Google Patents

Description

  The present invention relates to a laser cutting method.

  When cutting metal workpieces with a laser, it is necessary to remove the molten metal from the cutting points in order to maintain the cutting quality. Conventionally, a nozzle is disposed in the vicinity of the cut portion, and the assist gas is injected to the cut portion through the nozzle, so that the molten metal is removed from the cut portion by the pressure by the injection.

  According to Patent Document 1 below, when cutting a steel plate by irradiating a laser beam while injecting gas onto the surface of the steel plate, the water for cooling is sprayed in the form of a mist around the laser light irradiated portion on the surface of the steel plate. The laser cutting method which cooled the laser beam irradiation part circumference | surroundings of the surface of the said steel plate by this, and suppressed the thermal deformation of the plate thickness direction of a steel plate is described.

Japanese Patent Laid-Open No. 2000-052081

  By the way, when there is a distance between the nozzle and the workpiece, and the pressure by injection of the assist gas can not act on the cut portion, the workpiece can be cut only by the irradiation of the laser; The molten metal generated by the laser irradiation continues to adhere to the cut portion of the workpiece by surface tension, and the amount of secondary products involved in the melting increases, which may lower the cutting quality. If the laser cutting location is a wall extending in the vertical direction, the laser irradiation location is broadened to make a wide area including the cutting location in a molten state, and the molten metal weighs itself from the cutting location of the workpiece Although it is possible to remove the molten metal from the cut portion by dropping the molten metal, the energy required for cutting may be increased by the amount of the spread of the laser irradiation portion and the cutting efficiency may be reduced. .

  From the above, the present invention has been made to solve the above-mentioned problems, and a laser cutting method capable of efficiently cutting a workpiece despite the absence of using an assist gas It is intended to be provided.

In the laser cutting method according to the first aspect of the present invention for solving the above-mentioned problems, a laser is transmitted, and a liquid film having a thickness at which liquid is vaporized by the laser irradiation is formed on the surface of the workpiece. was supplied by spraying the liquid against the workpiece, and the while intermittently imparting an impact to the irradiation position of the laser in workpiece, the molten region consisting of melt the workpiece is melted The molten material flows from the melting region by the impact by continuing to irradiate the laser with a pulse to the workpiece so that the melting region expands in the thickness direction of the workpiece. It is characterized by having done so.

A laser cutting method according to a second aspect of the present invention for solving the above-mentioned problems is the laser cutting method according to the first aspect described above, wherein the supply of the liquid is carried out at a place away from the irradiation point of the laser. It is characterized by

Laser cutting method according to a third invention for solving the above problems, a laser cutting method according to the first or the second invention described above, the liquid is characterized in that it is water.

A laser cutting method according to a fourth invention for solving the above-mentioned problems is the laser cutting method according to any one of the first to third inventions, wherein the work is a pipe, The inside of the pipe is closed by a closing member so as to include the irradiation point of the laser, and the inside of the line closed by the closing member is depressurized.

A laser cutting method according to a fifth aspect of the present invention for solving the above-mentioned problems is the laser cutting method according to any one of the first to the fourth aspects described above, wherein the irradiation of the laser is the workpiece It is characterized by being performed to the wall surface extended in the up-and-down direction in the above.

According to the laser cutting method according to the first aspect of the present invention, the recoil pressure accompanying metal vapor generation at the time of irradiation with the pulse of the laser repeatedly acts on the molten pool, and the vapor pressure at the time of vaporization of the liquid is also a workpiece To facilitate the flow of the melt out of the melting zone. Thereby, compared with the case where only the laser is continuously irradiated without using the assist gas, the workpiece can be cut efficiently , and the deterioration of the cutting quality can be suppressed. Furthermore, a liquid film of uniform thickness can be easily formed on the surface of the workpiece, and a reduction in the cutting efficiency of the workpiece due to the size of the liquid film can be suppressed. The pressure resulting from the pressure can be reliably transmitted to the workpiece.

According to the laser cutting method relating to the second aspect of the present invention, it is possible to prevent the laser from being scattered by coming into contact with the liquid.

According to the laser cutting method relating to the third aspect of the present invention, since the vapor pressure of water is large, the pressure resulting from the impact can be efficiently transmitted to the workpiece, and the workpiece can be made more efficient. It can be cut off.

According to the laser cutting method relating to the fourth aspect of the present invention, it is possible to promote the outflow of the melt from the melting region, and it is possible to cut the workpiece more efficiently.

According to the laser cutting method relating to the fifth aspect of the present invention, the gravity of the melt also acts on the outflow of the melt from the melting region, and the workpiece can be cut more efficiently.

It is explanatory drawing of the laser cutting method which concerns on 1st embodiment of this invention, Comprising: The state at the time of laser irradiation is shown in FIG. 1 (a), and the state at the time of cutting is shown in FIG.1 (b). It is explanatory drawing of the laser cutting method which concerns on 2nd embodiment of this invention, Comprising: The state at the time of laser irradiation is shown in FIG. 2 (a), and the state at the time of cutting is shown in FIG.2 (b). It is explanatory drawing of the laser cutting method which concerns on 3rd embodiment of this invention, Comprising: The whole is shown in FIG. 3 (a), and expansion of the surrounding line III is shown in FIG.3 (b).

  Although the embodiment of the laser cutting method according to the present invention will be described based on the drawings, the present invention is not limited to only the following embodiments described based on the drawings.

First Embodiment
A laser cutting method according to a first embodiment of the present invention will be described based on FIG.

  The laser cutting apparatus used in the laser cutting method according to the present embodiment is, as shown in FIG. 1A, a laser oscillator 11, an optical fiber 12 connected to the laser oscillator 11, and a laser at the other end of the optical fiber 12. The laser processing head 13 connected via the emitting unit 14 is provided. The laser processing head 13 is provided with a nozzle 15. The nozzle 15 is disposed with its tip directed to the side. The workpiece (workpiece) W1 to be cut by the laser cutting device has a surface (wall surface) W1a extending in the vertical direction. That is, the nozzle 15 is disposed to face the surface W1a of the workpiece W1. The workpiece W1 is, for example, a metal plate (for example, a steel plate) or a pipe (for example, a steel pipe) which has a thickness of 1 mm to 200 mm and can be cut by laser irradiation using an assist gas.

  The above-mentioned laser cutting apparatus further includes a control device 50 that controls the laser oscillator 11. The laser oscillator 11 is controlled by the controller 50 to adjust the laser output and pulse width oscillated from the laser oscillator 11. Further, the laser oscillator 11 is controlled by the control device 50, and the cutting speed at which the workpiece W1 is cut by the laser 1 emitted from the nozzle 15 is adjusted.

Here, the laser cutting method by the above-mentioned laser cutting apparatus is demonstrated using FIG. 1 (a) and FIG.1 (b).
First, as shown in FIG. 1A, the nozzle 15 is disposed so as to face the surface W1a of the workpiece W1 which is a cutting point, and the control device 50 controls the laser oscillator 11. As a result, the laser 1 oscillated from the laser oscillator 11 is irradiated with a pulse onto the surface W1a of the workpiece W1 which is a cut portion through the optical fiber 12, the laser emitting unit 14, the laser processing head 13 and the nozzle 15. The workpiece W1 is heated by the irradiation of the laser 1, and a molten region W1d made of the molten material W1e in which the workpiece W1 is melted is generated.

  By continuing the irradiation with the pulse of the laser 1, the melting region W1d is expanded in the thickness direction of the workpiece W1. When the laser 1 is applied to the workpiece W1 in pulses, the laser 1 intermittently applies the recoil pressure 4 to the workpiece W1 to the workpiece W1.

  Further, when the molten region W1d is expanded from the front surface W1a to the rear surface W1b of the work W1 by continuing the irradiation of the laser 1, as shown in FIG. 1B, the metal vapor at the time of irradiating the work W1 with the laser 1 The recoil pressure 4 accompanying the generation is intermittently transmitted from the surface W1a side to the back surface W1b side of the work W1, and the pressure P1 applied intermittently promotes the flow of the molten material W1e from the melting region W1d, and the melting is concerned The thing W1e will flow out.

  Therefore, according to the laser cutting method according to the present embodiment, while intermittently applying an impact to the portion of the workpiece W1 irradiated with the laser 1, the molten region W1d made of the molten material W1e in which the workpiece W1 is melted is generated By irradiating the workpiece W1 with a pulse of laser so that the melted region W1d expands in the thickness direction of the workpiece W1, the recoil pressure 4 accompanying metal vapor generation at the time of the irradiation is the thickness of the workpiece W1 It is transmitted in the direction to encourage the flow of the melt (dross) W1e from the melting region W1d. Thereby, compared with the case where only the laser is continuously irradiated without using the assist gas, the melt W1e can be efficiently removed from the cut portion, and the work W1 can be cut efficiently. Thereby, the deterioration of the cutting quality can be suppressed.

The peak power density of the above-described laser 1 is preferably 10 kW / mm ² or more. The pulse width of the laser 1 is preferably 0.1 ms to 500 ms. This is because if the peak power density and pulse width of the laser 1 are within the above-mentioned range, the distance between the nozzle 15 and the work W1 is 3 of the diameter of the assist gas nozzle where the assist gas can not apply sufficient pressure to the laser irradiation location. Even when the distance is twice or more, the above-mentioned work W1 is heated by the irradiation of the pulse of the laser 1 to generate a molten region W1d composed of the molten material W1e which is melted the work W1 and irradiate the work W1 with the laser 1 This is because the recoil pressure 4 accompanying metal vapor generation at the time is transmitted in the thickness direction of the work W1, and the flow of the melt W1e from the melting region W1d is surely promoted.

  As described above, the surface W1a of the workpiece W1 is preferably extended in the vertical direction. As a result, the gravity of the molten material W1e also acts on the outflow of the molten material W1e from the melting region W1d, and the work W1 can be cut more efficiently.

Second Embodiment
A laser cutting method according to a second embodiment of the present invention will be described based on FIG. In this embodiment, an apparatus is used in which a water supply apparatus is added to the laser cutting apparatus used in the laser cutting method according to the above-described first embodiment. In the present embodiment, the same reference numerals are appended to the same devices as in the first embodiment.

  The laser cutting apparatus used by the laser cutting method which concerns on this embodiment is provided with the water supply apparatus (water spray apparatus) 20, as shown in FIG. The water supply device 20 includes a spray nozzle 21, a water supply pipe 22, a pump 23, and a water storage tank 24. The water (liquid) 2 is stored in the water storage tank 24. The proximal end side of the water supply pipe 22 is connected to the water storage tank 24. The distal end side of the water supply pipe 22 is connected to the proximal end side of the spray nozzle 21. The pump 23 is provided to the water supply pipe 22.

  The control device 50 included in the above-described laser cutting device is connected to the pump 23 of the water supply device 20 by a signal line, and the control device 50 can control the operation of the pump 23. The control device 50 controls the operation of the pump 23 so that the water 2 in the water storage tank 24 flows through the water supply pipe 22 and is sprayed from the spray nozzle 21 onto the surface W1a of the workpiece W1. The amount of spray (supply) is adjusted. The spray amount (supply amount) of the water 2 to the surface W1a of the workpiece W1 by the spray nozzle 21 sprays water on the laser irradiation location so as to suppress the thermal deformation of the steel plate in the thickness direction, and around the laser irradiation location Unlike the laser cutting method described in the above-mentioned Patent Document 1 for cooling the liquid film 3 having a thickness t (for example, several tens of μm to 100 μm) which transmits the laser 1 and vaporizes the water 2 by the irradiation of the laser 1. It is preferable to adjust to form on the surface W1a of the work W1. As a result, the laser 1 reliably irradiates the surface W1a of the workpiece W1, and the portion of the workpiece W1 irradiated with the laser 1 can be reliably heated to generate the melted region W1d in the workpiece W1. The vapor pressure when the water 2 is vaporized can be transmitted to the work W1.

Here, the laser cutting method by the above-mentioned laser cutting apparatus is demonstrated using FIG. 2 (a) and FIG.2 (b).
First, as shown in FIG. 2 (a), the nozzle 15 is disposed opposite to the surface W1a of the workpiece W1 which is the cutting location, while the spray nozzle 21 is separated from the cutting location (the laser 1 in FIG. 2 (a)). The laser oscillator 11 and the pump 23 are controlled by the control device 50 so as to face the upper side of the irradiation point). As a result, the laser 1 oscillated from the laser oscillator 11 is irradiated with a pulse onto the surface W1a of the workpiece W1 which is a cut portion through the optical fiber 12, the laser emitting unit 14, the laser processing head 13 and the nozzle 15. Further, the water 2 in the water storage tank 24 is sprayed from the spray nozzle 21 to the surface W1a of the work W1 through the water supply pipe 22. While the liquid film 3 of the above-mentioned thickness t is formed on the surface W1a of the work W1, the work W1 is heated by the irradiation of the laser 1, and a molten region W1d made of the molten material W1e in which the work W1 is melted is generated. .

  By continuing the irradiation with the pulse of the laser 1, the melting region W1d is expanded in the thickness direction of the workpiece W1. When the laser 1 is irradiated to the workpiece W1 by a pulse, the impact W5 at the time when the laser 1 hits the workpiece W1 and the vapor pressure when the water 2 is vaporized by the laser 1 is the workpiece W1. Will be applied intermittently.

  Furthermore, when the melting region W1d is expanded from the front surface W1a to the rear surface W1b of the work W1 by continuing the irradiation with the pulse of the laser 1, as shown in FIG. 2 (b), the pressure P2 due to the impact 5 is intermittent. The intermittent pressure P2 accelerates the flow of the melt W1e from the melting region W1d and the flow of the melt W1e starts flowing out from the surface W1a side of the work W1.

  Therefore, according to the laser cutting method according to the present embodiment, the shock 5 due to the time when the laser 1 hits the surface W1a of the work W1 and the vapor pressure at the time of vaporization of the water 2 by the laser 1 becomes the pressure P2 of the work W1. Since it acts intermittently in the thickness direction, the molten material W1e can be efficiently removed from the molten region W1d generated by the irradiation of the laser 1.

  In addition, it is preferable that the spraying (supply) of the water 2 to the surface W1a of the workpiece W1 by the spray nozzle 21 be performed at a place away from the irradiation place of the laser 1. Thereby, the laser 1 can be prevented from being scattered by the contact with the water 2.

  The water 2 is preferably supplied to the surface W1a of the work W1 by spraying. Thereby, the liquid film 3 of uniform thickness can be easily formed in a wide area of the surface W1a of the work W1, and the reduction of the cutting efficiency of the work W1 caused by the size of the liquid film 3 can be suppressed. Can. Further, the pressure P2 caused by the impact 5 can be reliably transmitted to the workpiece W1.

  It is preferable to supply water 2 as a liquid to the surface W1a of the work W1. This is because the steam pressure of the water 2 is large, the pressure P2 resulting from the impact 5 can be efficiently transmitted to the work W1, and the work W1 can be cut more efficiently.

Third Embodiment
A laser cutting method according to a third embodiment of the present invention will be described based on FIG. In the present embodiment, an apparatus is used in which a pressure reducing device is added to the laser cutting apparatus used in the laser cutting method according to the second embodiment described above. In the present embodiment, the same devices as those of the second embodiment are indicated by the same reference numerals.

  The laser cutting apparatus used by the laser cutting method which concerns on this embodiment is provided with the pressure reduction apparatus 30, as shown to Fig.3 (a). The workpiece (workpiece) W2 to be cut by the laser cutting device has a surface (wall surface) W2a extending in the vertical direction. The workpiece W2 is, for example, a metal pipe (for example, a steel pipe) which has a thickness of 1 mm to 20 mm and can be cut by laser irradiation using an assist gas. The pressure reducing device 30 includes closing members 31 and 32, an exhaust pipe 33 and a blower 34. The closing members 31 and 32 are arranged such that the region surrounded by the closing members 31 and 32 includes the cut portion in the workpiece W2. That is, one closing member 31 is disposed in the work W 2 so as to close the upper side of the irradiation position of the laser 1. The other closing member 32 is disposed in the workpiece W2 so as to close the lower side of the irradiation point of the laser 1. An opening 31 a is provided in the one closing member 31. The proximal end of the exhaust pipe 33 is provided in connection with the opening 31 a of the closing member 31. The blower 34 is provided in the exhaust pipe 33.

  The control device 50 included in the above-described laser cutting device is connected to the blower 34 of the pressure reducing device 30 by a signal line, and the control device 50 can control the operation of the blower 34. The control device 50 controls the operation of the blower 34 to adjust the closed space formed by the closing members 31 and 32 to a negative pressure.

Here, the laser cutting method by the above-mentioned laser cutting apparatus is demonstrated using FIG. 3 (a) and FIG.3 (b).
First, as shown in FIG. 3A, the nozzle 15 is disposed to face the wall surface W2a of the workpiece W2 which is the cutting location, while the spray nozzle 21 is separated from the cutting location (the laser 1 in FIG. 3A). The laser oscillator 11 and the pump 23 and the blower 34 are controlled by the control unit 50 so as to face the upper side of the irradiation point). As a result, the laser 1 oscillated from the laser oscillator 11 is irradiated with a pulse onto the surface W2a of the workpiece W2 which is a cut portion through the optical fiber 12, the laser emitting unit 14, the laser processing head 13 and the nozzle 15. Further, the water 2 in the water storage tank 24 is sprayed from the spray nozzle 21 to the surface W2a of the workpiece W2 through the water supply pipe 22. Air 6 is exhausted from the area surrounded by the closing members 31 and 32 through the exhaust pipe 33. At this time, while the inside of the region has a negative pressure, the liquid film 3 of the above-mentioned thickness t is formed on the surface W2a of the workpiece W2, and the workpiece W2 is heated by the irradiation of the laser 1, and the workpiece W2 is melted. A molten zone W2d made of the molten material W2e is produced.

  By continuing the irradiation with the pulse of the laser 1, the melting region W2d is expanded in the thickness direction of the workpiece W2. When the laser 1 irradiates the workpiece W2 with a pulse, the workpiece W2 is shocked with the vapor pressure when the laser 1 hits the workpiece W2 and when the water 2 is vaporized by the laser 1 It will be applied intermittently.

  Furthermore, when the melting region W2d is expanded from the surface W2a of the workpiece W2 to the inner surface W2c by continuing the irradiation with the pulse of the laser 1, as shown in FIGS. 3 (a) and 3 (b), the laser 1 Shock P5 due to the vapor pressure when the water 2 is vaporized by the laser 1, and the pressure P3 that the pressure in the area is negative pressure with respect to the work W2 It will be transmitted to As a result, the flow of the melt W2e from the melting region W2d is promoted, and the melt W2e flows out.

  Therefore, according to the laser cutting method according to the present embodiment, the impact 5 by the laser 1 hitting the surface W 2 a of the workpiece W 2 and the vapor pressure at the time of vaporization of the water 2 by the laser 1 Since the pressure P3 of being a pressure acts intermittently in the thickness direction of the work W2, the melt W2e can be efficiently removed from the melting region W2d generated by the irradiation of the laser 1.

  As described above, the surface W2a of the workpiece W2 is preferably extended in the vertical direction. As a result, the gravity of the melt W2e also acts on the outflow of the melt W2e from the melting region W2d, and the work W2 can be cut more efficiently.

  INDUSTRIAL APPLICABILITY The laser welding method according to the present invention can cut a workpiece efficiently even without using an assist gas, and therefore can be extremely usefully used in various industries.

1 Laser 2 Water (Liquid)
3 Liquid film 4 Recoil pressure 5 Impact 11 Laser oscillator 12 Optical fiber 13 Laser processing head 14 Laser emitting portion 15 Nozzle 20 Water supply device (water spray device)
21 spray nozzle 22 water supply pipe 23 pump 24 water storage tank 30 pressure reducing device 31 closing member (closing plate)
31a opening 32 closing member (closing plate)
33 exhaust pipe 34 blower 50 controller t thickness P1, P2, P3 pressure W1 workpiece (workpiece)
W1a surface (wall surface)
W1b Back side W1d Melting area W1e Melt (Dross)
W2 Workpiece (workpiece)
W2a surface (wall surface)
W2c Inner surface W2d Melting zone W2e Melt (Dross)

Claims (5)

The liquid is supplied to the workpiece by spraying so as to form a liquid film on the surface of the workpiece through which the laser is transmitted and the liquid is vaporized by the irradiation of the laser, and while intermittently imparting an impact to the irradiation position of the laser in workpiece, the workpiece to generate a molten region consisting of melt and melt, the molten area in the thickness direction of the workpiece A laser cutting method characterized in that the molten material is made to flow from the melting region by the impact by continuing to irradiate the laser with a pulse to the workpiece so as to expand. The laser cutting method according to claim 1 , wherein
The supply of the liquid is performed at a place away from the irradiation place of the laser. A laser cutting method according to claim 1 or claim 2 , wherein
The said liquid is water. The laser cutting method characterized by the above-mentioned. A laser cutting method according to any one of claims 1 to 3 , wherein
The workpiece is a pipe,
The inside of the pipe is closed by a closing member so as to include the irradiation point of the laser, and the inside of the line closed by the closing member is depressurized. A laser cutting method according to any one of claims 1 to 4 , wherein
The laser cutting method is characterized in that the irradiation of the laser is performed on a wall surface extending in the vertical direction of the workpiece.

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