JP2007296580A - Laser piercing method and machining equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser piercing method and a machining equipment capable of forming a piercing hole of a desired diameter with the high machining efficiency and reducing the manufacturing cost while preventing an increase of the piercing hole diameter when piercing a metallic work such as a steel plate. <P>SOLUTION: In a processing equipment 1, a machining portion of a metallic subject W to be machined is irradiated with a laser beam L2, an assist gas G is jetted toward the machining portion from a nozzle 3 coaxially arranged with the laser beam L2 to cover the machining portion, and a piercing hole is machined in the metallic subject W. The machining equipment is provided with a control means 10 for machining the piercing hole H while circumferentially shifting the nozzle 3 within a range from a machining start point to 5 mm, after offsetting the nozzle 3 from the machining start point for starting the machining of the piercing hole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of piercing a workpiece by a laser cutting machine and a processing apparatus using the piercing method.

Conventionally, when a workpiece such as a steel plate is to be cut with a laser cutting machine, a small through hole of φ several millimeters is provided by laser piercing at a position that is a starting point for cutting, and cutting is performed from there. Done.
This through-hole is important for increasing the finishing accuracy of the workpiece without reducing the material yield, and is as small as possible and within the desired dimensions as long as it does not interfere with the subsequent cutting process. It is desirable to be formed.

FIG. 11 shows a schematic configuration of a laser torch 100 of a laser cutting machine. The laser torch 100 includes a nozzle 102 and a condenser lens 104, and the nozzle 102 is formed in a cylindrical body. The laser light L2 can pass from the base end part 102a toward the opening part 102b on the front end side, and the condenser lens 104 is disposed on the base end part 102a side.
Further, the opening 102 b of the nozzle 102 is coaxial with the laser light L 2 that has passed through the condenser lens 104.
In addition, when the workpiece W is melted and evaporated by the irradiated laser beam L2, the nozzle 102 is provided with an introduction path for introducing an assist gas G for burning the workpiece W by an oxidation reaction into the nozzle 102. 103 is provided.

When processing the piercing hole H2 in the workpiece W using the laser torch 100, the opening of the nozzle 102 is opposed to the workpiece W, and the assist gas G is introduced into the nozzle 102 from the introduction path 103. The introduced assist gas G is jetted from the opening 102b of the nozzle 102 so as to cover the processed portion of the workpiece W.
Next, when the laser beam L1 is irradiated from the laser torch 100, the laser beam L2 having a focal point near the surface of the workpiece W is condensed by the condenser lens 104. In this way, the laser beam L2 focused on the focal point in the vicinity of the surface of the workpiece W melts and evaporates the workpiece W to form the molten pool 105, and the assist gas G injected from the opening 102b. By being oxidized and burned, the melt is removed by the jet of the assist gas G. As such a technique for processing the piercing hole H2 by laser light, for example, a technique disclosed in Patent Document 1 is disclosed.

Further, when the piercing hole H2 is machined, if excessive oxidation or combustion reaction occurs in the molten metal generated in the molten pool 105 formed in the workpiece W, the diameter of the piercing hole H2 increases, and the material path is increased. The yield drops.
On the other hand, for example, when laser light is oscillated in the form of pulses and piercing hole processing is performed, the accuracy of the piercing hole diameter is improved, but the processing efficiency is remarkably reduced.
Therefore, for example, Patent Document 2 discloses a technique for improving the cutting accuracy of the piercing hole H2 when piercing hole processing is performed using laser light.
JP 2001-47268 A Japanese Patent No. 3292201

However, according to the above method, it is necessary to previously provide a groove for discharging the melt, and there is a problem that the piercing hole becomes large due to the presence of the discharge groove.
Therefore, there has been a demand for a laser piercing method and a processing apparatus that can process a piercing hole having a desired dimension with high accuracy while maintaining high processing efficiency.

  The present invention has been made in consideration of such circumstances, and when performing piercing processing on a metal workpiece such as a steel plate, the piercing hole diameter is prevented from becoming large, and with high processing efficiency. It is an object of the present invention to provide a laser piercing method and a processing apparatus capable of forming a piercing hole having a desired diameter and reducing the manufacturing cost.

In order to solve the above problems, the present invention proposes the following means.
According to the first aspect of the present invention, an assist gas is jetted from a nozzle arranged coaxially with the laser beam toward the processing portion while irradiating the processing portion of the workpiece with the laser light, and the processing is performed by the assist gas. A laser piercing method of processing a piercing hole in the processing portion, wherein the piercing hole is processed while moving the nozzle within a range of 5 mm from the processing starting point after the irradiation of the laser beam is started. Features.

According to a seventh aspect of the present invention, an assist gas is jetted from a nozzle disposed coaxially with the laser beam toward the processing portion while irradiating the processing portion of the workpiece with a laser beam. A processing apparatus that covers the processing portion and processes a piercing hole in the processing portion,
It is characterized by comprising control means for processing the piercing hole while moving the nozzle within a range of 5 mm from the processing starting point after the start of irradiation with the laser beam.

  According to the laser piercing method and the processing apparatus of the present invention, after starting to irradiate the laser beam and starting to process the piercing hole, the center of the nozzle is offset from the processing start point and moved within a range of 5 mm from the processing start point. Therefore, the center of the pressure distribution of the assist gas is offset from the center of the molten pool. As a result, the pressure distribution of the assist gas is not concentric with the center of the molten pool, the pressure distribution of the assist gas at the opening of the molten pool becomes asymmetrical at the center of the molten pool, and the pressure balance at the opening of the molten pool is biased .

When the pressure distribution of the assist gas was concentric with the center of the molten pool, the assist gas acted like a lid of the molten pool, and the melt was stably held in the molten pool. Are biased, and a region where the pressure applied to the melt is high and a region where the pressure is low are generated in the opening of the molten pool. As a result, the melt is moved by the pressure difference from the high pressure area to the low pressure area, and the discharge out of the molten pool is promoted.
As a result, the molten material stored in the molten pool is reduced, and excessive oxidation reaction and combustion are suppressed, so that the piercing hole diameter is reduced.

In addition, since the melt discharged from the molten pool is dispersed and discharged around the molten pool by moving the nozzle within the range of 5 mm from the processed starting point in the vicinity of the processed starting point, the heat released from the discharged material Are not concentrated in one place, and the workpiece around the piercing hole is locally overheated and excessive oxidation reaction is suppressed, and expansion of the piercing hole is suppressed.
As a result, the molten dross is suppressed from staying in the molten pool, and the expansion of the piercing hole is suppressed.
As a result, even when laser light is continuously irradiated, piercing holes with high hole diameter accuracy can be easily and reliably formed while ensuring high productivity by continuous irradiation.
Here, the significance of the movement of the nozzle within a range of 5 mm from the processing start point is that the piercing hole to be processed becomes large when the distance from the processing start point is 5 mm or more, and a difference from the case where the nozzle is not moved cannot be found. .

  A second aspect of the present invention is the laser piercing method according to the first aspect, characterized in that the nozzle is moved around the processing starting point.

  The invention according to claim 8 is the processing apparatus according to claim 7, wherein the control means includes a circulation control means for moving the nozzle around the machining start point. To do.

  According to the laser piercing method and the processing apparatus according to the present invention, after starting the processing of the piercing hole, the center of the nozzle is offset from the processing start point, and is moved around the processing start point within a range of 5 mm from the processing start point. Therefore, after the offset, the center of the pressure distribution of the assist gas is always offset from the center of the molten pool until the piercing finishes the hole processing. As a result, the pressure balance at the opening of the molten pool is biased, the discharge of the melt to the outside of the molten pool is promoted, the molten material stored in the molten pool is reduced, and excessive oxidation reactions and combustion are suppressed. Thus, the diameter of the piercing hole is reduced.

  A third aspect of the present invention is the laser piercing method according to the first aspect, wherein the nozzle is moved along a trajectory including reciprocation.

  The invention according to claim 9 is the processing apparatus according to claim 7, wherein the control means includes reciprocation control means for moving the nozzle along a locus including reciprocation. Do

According to the laser piercing method and the processing apparatus according to the present invention, after starting to process the piercing hole, the nozzle is moved along a locus including reciprocating movement within a range of 5 mm from the processing starting point.
The reciprocating movement of the nozzle with a simple trajectory makes the nozzle easy to move and enables high-speed movement. Abrupt pressure bias is applied to the molten material in the molten pool, and large pressure fluctuations cause the nozzle to move out of the molten pool. The discharge of the melt is promoted. As a result, the melt in the molten pool is reduced, and the piercing hole diameter is reduced by suppressing the oxidation reaction and combustion.

  According to a fourth aspect of the present invention, in the laser piercing method according to the first aspect, the moving is characterized in that the nozzle is moved in a zigzag manner.

  The invention according to claim 10 is the processing apparatus according to claim 7, wherein the control means includes zigzag control means for moving the nozzle in a zigzag manner.

According to the laser piercing method and the processing apparatus according to the present invention, after starting to process the piercing hole, the nozzle is moved in a zigzag manner within a range of 5 mm from the processing start point.
The nozzle moves in a zigzag manner with a reciprocating movement with a simple trajectory and a movement in a direction perpendicular to the reciprocating movement, so that the nozzle can be moved easily and at a high speed, and a movement perpendicular to the reciprocating movement direction can be performed. By doing so, a pressure bias is imparted over a wide range in the molten pool, so that an abrupt pressure bias is applied to the melt in the molten pool, and discharge of the melt out of the molten pool is promoted. As a result, the melt in the molten pool is reduced, and the piercing hole diameter is reduced by suppressing the oxidation reaction and combustion.

Invention of Claim 5 is the laser piercing method in any one of Claims 1-4, Comprising:
The oxygen concentration C of the assist gas injected from the nozzle is determined in accordance with the thickness t of the processing part that performs the piercing hole processing,
The oxygen concentration C is
In the range of 0 <t <8 mm, 0 <C <99.9
In the range of 8 ≦ t <13.5 mm, 0 <C ≦ −1.65t + 111.2
In the range of 13.5 ≦ t ≦ 26.33 mm,
5.28t−71.28 ≦ C ≦ −1.65t + 111.2
C: oxygen concentration (Vol%), t: thickness of processed part (mm)
It is characterized by being.

  Invention of Claim 11 is a processing apparatus in any one of Claims 7-10, Comprising: The said control means uses oxygen concentration C of the assist gas injected from the said nozzle as said piercing hole processing. An oxygen concentration adjusting means for determining the thickness corresponding to the thickness t of the processed portion is provided.

According to the laser piercing method and the processing apparatus according to the present invention, the oxygen concentration C of the assist gas injected from the nozzle is set to the thickness t, for example, the plate thickness t, of the processing portion that performs the piercing hole processing of the metal workpiece. Since the piercing hole machining is performed at the oxygen concentration C, excessive oxidation and combustion of the workpiece are suppressed, and the amount of noro is reduced. Therefore, in the plate thickness t of each workpiece A piercing hole having a smaller diameter can be easily and reliably formed in terms of material yield and quality.
In addition, by adjusting the oxygen concentration C of the assist gas, even when laser light is continuously irradiated, excessive oxidation and combustion are suppressed, and while maintaining high productivity by continuous irradiation, the pore diameter is reduced. A small piercing hole can be formed easily and reliably.
In addition, even when laser light is continuously irradiated, excessive oxidation and combustion are suppressed by adjusting the oxygen concentration C of the assist gas, and piercing with high hole diameter accuracy is ensured while ensuring high productivity by continuous irradiation. Holes can be made easily and reliably without relying on skilled technicians.

  A sixth aspect of the present invention is the laser piercing method according to any one of the first to fifth aspects, wherein after passing through the piercing hole, the nozzle is placed on the surface of the workpiece around the piercing hole. After moving upward and penetrating the piercing hole, the nozzle is moved above the surface of the workpiece around the piercing hole, and the laser beam is irradiated to remelt the dross and the assist gas from the nozzle. It is characterized in that the dross formed around the piercing hole is removed by revolving around the piercing hole while spraying.

  A twelfth aspect of the present invention is the processing apparatus according to any one of the seventh to eleventh aspects, wherein the control means passes through the piercing hole and then passes through the piercing hole, and then the nozzle. Is moved above the surface of the workpiece around the piercing hole, irradiates the laser beam to remelt the dross and circulates around the piercing hole while jetting assist gas from the nozzle, A dross removing means for removing dross formed around the piercing hole is provided.

According to the laser piercing method and the processing apparatus according to the present invention, after the piercing hole penetrates, the nozzle is moved above the surface of the workpiece around the piercing hole, and the dross is remelted by irradiating the laser beam. Since it moves around the piercing hole while injecting the assist gas from the nozzle, the dross formed on the workpiece surface around the piercing hole is easily melted and removed by the assist gas injection pressure, It can be easily and efficiently removed, and as a result, finishing around the piercing hole can be easily and reliably performed to produce a high quality piercing hole.
In addition, since the assist gas is injected from a short distance while the nozzle is moved around and the laser beam is irradiated to remelt the dross, the dross can be reliably removed with a small amount of assist gas. As a result, the processing time and processing cost can be greatly reduced.

  According to the laser piercing method and the processing apparatus according to the present invention, for example, when processing a piercing hole in a workpiece such as a steel plate, the pressure distribution of the assist gas formed at the opening of the molten pool during the piercing hole processing The piercing hole with the desired hole diameter can be formed with high efficiency and high accuracy by suppressing the excessive oxidation reaction in the hole by smoothly discharging the dross generated in the hole to the outside of the hole. The manufacturing cost can be reduced while forming.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a state in which the laser torch 2 and the piercing hole H according to this embodiment are processed. The laser torch 2 includes a nozzle 3 and a condenser lens 6, and the nozzle 3 is a cylindrical body. The laser light L1 that has been formed through the condenser lens 6 is condensed and irradiated as laser light L2 from the ejection port 3b.
The optical axis of the laser beam L2 and the nozzle 3 are configured coaxially and share the axis O1, and the axis O1 is coaxial with the central axis OG of the pressure distribution of the assist gas G injected from the nozzle 3. .

An assist gas is introduced into the nozzle 3 from the introduction path 4, and the workpiece W melted and evaporated by the laser beam L2 irradiated by being injected from the injection port 3b is burned by an oxidation reaction.
In this embodiment, the processing starting point when processing the piercing hole in the workpiece W and the position of the center of the piercing hole H substantially coincide with each other, and the direction in which the piercing hole H extends through the center of the piercing hole H. Since the axis OH extending in the direction passes through the processing starting point, the processing starting point can be specified on the surface of the workpiece W.

  FIG. 1 is a view showing the nozzle 3 immediately after starting to process the piercing hole H. The assisting gas G is injected with the injection port 3b of the nozzle 3 facing the workpiece W, and the workpiece W Are covered with the assist gas G, and the laser beam L2 is irradiated to melt and evaporate the workpiece W. At this time, the workpiece W is melted to form a molten pool 60, which is oxidized and burned by the assist gas G, and the melt is removed by the jet of the assist gas G. Further, a material that is melted, evaporated, oxidized, and burned becomes dross and is stored in the molten pool 60 as a melt, or around the piercing hole H of the material W by a jet of assist gas G. To be attached to.

FIG. 2 is a schematic view of a machining apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a machining apparatus, reference numeral 2 denotes a laser torch, and reference numeral 10 denotes a piercing control unit (control means).
The processing apparatus 1 includes a laser torch 2, a piercing control unit 10, a processing data input unit 30, an oxygen supply source 41, a nitrogen supply source 43, a laser oscillator 45, and a nozzle 3 nozzle provided in the laser torch 2. And a driving member 80 such as an XYZ table for moving the position of the workpiece in the XYZ coordinate direction of the three-dimensional space (in this embodiment, the surface of the workpiece is in the XY coordinate direction and the Z coordinate is the height direction). ing.

The piercing control unit 10 includes a processing unit 12, a data table 13, a nozzle movement control unit 11, an oxygen concentration adjustment unit (oxygen concentration adjustment unit) 20, and a dross removal control unit (dross removal unit) 40. Based on the input data input from the processing data input unit 30, an appropriate processing condition is determined and the driving member 80 is driven to move the laser torch 2 in the XYZ directions of the three-dimensional space, thereby ejecting the nozzle 3. The position of 3b is moved, and the assist gas G is supplied to the nozzle 3 through the introduction path 4.
The processing data input unit 30 includes a plate thickness input unit (thickness input unit) 31a, a piercing hole size input unit 31b, a piercing hole processing condition input unit 31c, a pressure mode input unit 31d, and a dross removal mode input. Part 31e.

The processing unit 12 and the data table 13 include processing units 12a, 12b, and 12c that share the nozzle movement control unit 11, the oxygen concentration adjustment unit 20, and the dross removal control unit 40, and data tables 13a, 13b, and 13c. Yes.
Further, in this embodiment, the assist gas G processes the piercing hole H having a desired piercing hole diameter by adjusting and mixing the amounts of oxygen and nitrogen supplied from the oxygen supply source 41 and the nitrogen supply source 43. And an assist for removing dross deposited on the surface of the workpiece W around the piercing hole H from the nozzle 3 as necessary. Gas G is injected.

  The nozzle movement control unit 11 includes a processing unit 12a, a data table 13a, an X driver 16a that drives the driving member 80 to control the X coordinate position of the laser torch 2, a Y driver 16b that controls the Y coordinate position, and a Z The processing unit 12a transmits an instruction signal to the X driver 16a, the Y driver 16b, and the Z driver 16c via the cables 15a, 15b, and 15c, and the X driver 16a. The Y driver 16b and the Z driver 16c supply power for moving the X coordinate position, the Y coordinate position, and the Z coordinate position to the drive member 80 via the cables 17a, 17b, and 17c.

The processing unit 12a receives the data on the plate thickness t to be pierced from the data table 13a via the signal cable 14 based on the data on the plate thickness t, the data on the piercing hole diameter d1, etc. input and transmitted by the machining data input unit 30. Data suitable for obtaining a desired piercing hole diameter in the steel sheet W, for example, the amount of eccentricity of the laser torch 2 (that is, the axis O1 of the nozzle 3 and the central axis OG of the pressure distribution of the assist gas G), the speed of the nozzle 3, the number of turns, Data such as the rotational movement speed is acquired and the X driver 16a, Y driver 16b, and Z driver 16c are instructed.
Here, moving the laser torch 2 means moving the axis O1 of the nozzle 3 and the central axis OG of the assist gas G.

The drive member 80 is mechanically connected to the laser torch 2, and by driving the drive member 80, the laser torch 2 and the nozzle 3 can be moved in the XYZ coordinate directions.
In this embodiment, the data table 13a stores the plate thickness t input from the piercing processing condition input unit 31c of the processing data input unit 30 and the movement trajectory format of the laser torch 2 corresponding to the piercing hole diameter d1. For example, (1) Circulating movement trajectory (the shape and size of a moving trajectory such as a circle or a polygon), torch speed, the number of laps, (2) The data constituting the reciprocating control means, such as the trajectory including the reciprocating movement (reciprocating stroke, etc.), the torch speed, the number of reciprocating movements, and the like (3) the data constituting the zigzag control means. A zigzag movement (for example, a reciprocating stroke in a reciprocating movement and a movement in a direction orthogonal to the reciprocating movement, a movement amount in the orthogonal direction, etc.) and a torch Time, data such as the number of such reciprocating movement are stored.

Here, the reciprocating movement of the laser torch 2 in (2) and (3) is one time when the offset laser torch 2 returns to the machining start point via the reciprocating stroke, but the movement of the laser torch 2 in the piercing hole machining. At this time, it is not always necessary to return to the position corresponding to the machining starting point. Therefore, the movement from the machining start point to any end of the reciprocating stroke and the number of reciprocations when returning from any end to the machining start point are each 1/4 times.
The data table 13a can also store other movement trajectories, and includes, for example, a case where the laser torch 2 is moved to a Z shape in zigzag movement.

  Based on the data input from the plate thickness input part 31a and the piercing hole size input part 31b of the processing data input part 30, the laser torch 2 is moved in the X-coordinate and Y-coordinate directions of the three-dimensional space, thereby ejecting the nozzle 3 The assist gas G pressure distribution applied to the opening 61 of the molten pool 60 is offset from the processing starting point by moving the central axis OG of the assist gas G injected from the port 3b, and the assist gas in the opening 61 of the molten pool 60 is offset. The pressure distribution of G becomes asymmetrical at the center of the molten pool 60, and the pressure balance at the opening of the molten pool 60 is biased.

The oxygen concentration adjustment unit (oxygen concentration adjustment means) 20 includes a processing unit 12b, a data table 13b, an oxygen flow rate adjustment circuit 21a, a nitrogen flow rate adjustment circuit 21b, a mixer 24, and a pressure adjustment valve 25. The processing unit 12b is connected to the data table 13b, the oxygen flow rate adjustment circuit 21a, the nitrogen flow rate adjustment circuit 21b, and the pressure adjustment valve 25 via signal cables 26a, 26b, and 28, respectively.
The data table 13b stores control data for obtaining an assist gas G having a predetermined oxygen concentration and injection pressure in the oxygen flow rate adjustment circuit 21a, the nitrogen flow rate adjustment circuit 21b, and the pressure adjustment valve 25.

  The oxygen flow rate adjustment circuit 21a and the nitrogen flow rate adjustment circuit 21b are connected to an oxygen supply source 41 and a nitrogen supply source 43, respectively. The oxygen supply source 41 and the nitrogen supply source 43 store liquefied oxygen and liquefied nitrogen, respectively. These liquefied oxygen and liquefied nitrogen are vaporized and supplied to the oxygen flow rate adjustment circuit 21a and the nitrogen flow rate adjustment circuit 21b.

The oxygen flow rate adjustment circuit 21a includes a mass flow controller 27a and a pipe, connects the oxygen supply source 41 and the mixer 24, and converts the flow rate of oxygen supplied from the oxygen supply source 41 through the pipe into the mass flow controller 27a. To adjust.
The nitrogen flow rate adjustment circuit 21b includes a mass flow controller 27b and a pipe, and connects the nitrogen supply source 43 and the mixer 24 to change the flow rate of nitrogen supplied from the nitrogen supply source 43 through the pipe. To adjust.

The oxygen and nitrogen whose flow rates are adjusted by the mass flow controllers 27a and 27b are supplied to the mixer 24, mixed, generated into the assist gas G having a predetermined oxygen concentration, and supplied to the nozzle 3 through the introduction path 4. It has become.
Further, for example, in order to obtain an assist gas G having a predetermined injection pressure P in the nozzle 3, for example, the pressure adjustment valve 25 adjusts the pressure to a predetermined pressure corresponding to the injection pressure P by control data from the processing unit 12a. It has come to be. In this embodiment, the nozzle 3 is provided with a storage portion for the assist gas G having a sufficiently large volume with respect to the injection port, and the injection pressure P of the assist gas G at the injection port is supplied from the pressure adjustment valve 25. The pressure is kept substantially equal to the pressure of the assist gas G.
In this embodiment, the control data for controlling the oxygen flow rate adjustment circuit 21a and the nitrogen flow rate adjustment circuit 21b is composed of opening degree data of the mass flow controllers 27a and 27b.

  Further, as necessary, when an instruction regarding pressure adjustment of the assist gas is input to the pressure mode input unit 31d, the processing unit 12a is input from the plate thickness input unit 31a by a signal from the pressure mode input unit 31d. In order to inject the assist gas G having the injection pressure P corresponding to the thickness t of the processed part of the workpiece W from the nozzle 3, the assist gas G having the pressure corresponding to the injection pressure P is supplied to the nozzle via the pressure adjustment valve 25. 3 is obtained from the data table 13 and instructed to the pressure regulating valve 25 via the signal cable 28.

The dross removal control unit (dross removal unit) 40 includes a processing unit 12c, a data table 13c, an X driver 16a, a Y driver 16b, and a Z driver 16c. The processing unit 12a includes the X driver 16a, Signals are transmitted to the Y driver 16b and the Z driver 16c, and the X driver 16a, the Y driver 16b, and the Z driver 16c supply power to the driving member 80.
The data table 13c also includes a distance offset from the axis OH of the piercing hole H (in this embodiment, (circular locus diameter d2) / 2), the height from the surface of the workpiece W, the nozzle Control data such as the orbital movement speed, the number of revolutions, and the orbital movement locus are stored.

  The processing data input unit 30 includes a plate thickness input unit 31a, a piercing hole size input unit 31b, a piercing hole processing condition input unit 31c, a pressure mode input unit 31d, and a dross removal mode input unit 31e. These are connected to the processing unit 12 via data cables 33a, 33b, 33c, 33d, and 33e, respectively.

The plate thickness input unit 31a inputs data related to the plate thickness (the thickness of the processed portion) t of a steel plate (metal workpiece) W, which is the workpiece W, for example.
The piercing hole size input unit 31b is configured to receive data of the piercing hole diameter d1 with respect to the plate thickness t of the steel plate W among the processing data for piercing.

  The piercing hole processing condition input unit 31c is, for example, (1) a circular movement trajectory (circular or polygonal and its size, which is data constituting the circular control means) for moving the laser torch 2 during the piercing hole processing. ), Torch speed, number of laps, orbital movement speed, etc. (2) trajectory including reciprocating movement (reciprocating stroke, etc.), data constituting the reciprocating control means, torch speed, number of reciprocating movements, (3) Zigzag movement (for example, a reciprocating stroke in a reciprocating movement and a movement in a direction orthogonal to the reciprocating movement, a movement amount in the orthogonal direction, etc.) that is data constituting the zigzag control means; Data such as the torch speed and the number of reciprocating movements can be input.

In the piercing process, the pressure mode input unit 31d supplies the assist gas G supplied to the nozzle 3 so that the melt in the piercing hole being processed is discharged outside the piercing hole so that the melt does not remain. When the pressure is increased (lower) and the assist gas G is injected from the nozzle 3 at a higher (lower) injection pressure P, an instruction is input and instruction data is transmitted to the processing unit 12. .
The dross removal mode input unit 31e is configured to input an instruction as to whether or not to operate the dross removal control unit after piercing hole processing.

Next, the operation of the processing apparatus 1 according to this embodiment will be described. Here, the case of the circular movement locus 71 including the circle shown in FIG. 5A will be described as an example.
(Nozzle movement controller)
First, the laser torch 2 is moved in the X-coordinate and Y-coordinate directions defined by the two orthogonal directions of the surface along the steel plate W by an operation unit (not shown), and the processing position of the piercing hole H (corresponding to the processing start point). Stop at the same time.
Next, piercing hole processing conditions are set, and data of the plate thickness t and the piercing hole diameter d1 are input to the plate thickness input unit 31a and the piercing hole size input unit 31b of the processing data input unit 30. (Step S1 in FIG. 3)
In this case, it is also possible for a person to directly input data relating to circular movement, movement including reciprocation, zigzag movement, and the like to the piercing hole processing condition input unit 31c and perform manual control.

Data relating to the plate thickness t and the piercing hole diameter d1 input to the plate thickness input unit 31a and the piercing hole size input unit 31b are transmitted to the processing unit 12 via the data cables 33a and 33b, respectively.
The processing unit 12a transmits the data regarding the plate thickness t and the piercing hole diameter d1 of the steel plate W transmitted from the plate thickness input unit 31a and the piercing hole size input unit 31b to the data table 13a, and the plate thickness t and the piercing hole diameter. Data relating to nozzle position control corresponding to d1 is acquired from the data table 13a. (Step S2 in FIG. 3)

The data received from the data table 13a by the processing unit 12a includes, for example, when the laser torch 2 makes a circular movement, a circular movement locus (for example, see FIG. 5A) of the axis O1 of the laser torch 2, an offset amount, and a circular movement speed. This corresponds to the number of laps.
Based on these data received from the data table 13, the processing unit 12 calculates time / position information for moving the drive member 80, and a start switch (not shown) is turned on to start piercing hole machining. Then, the calculation result is transmitted to the X driver 16a, Y driver 16b, and Z driver 16c via the signal cables 15a, 15b, and 15c, and each driver is driven.
In the description of this embodiment, the X driver 16a and the Y driver 16b move the drive member 80 in the X coordinate direction and the Y coordinate direction to move the axis O1 of the laser torch 2 around the machining start point.

When the start switch is turned on, the laser oscillator 45 is activated to irradiate the laser beam L1, and the irradiated laser beam L1 is guided to the condenser lens 6 via an optical path (not shown). It passes through and is focused on L2, and is applied to the steel sheet W.
At this time, the assist gas G is introduced into the nozzle 3 of the laser torch 2 prior to the irradiation with the laser light L1, and the assist gas G is ejected from the ejection port 3b at the tip of the nozzle 3 toward the processed portion of the steel plate W. Then, a coating of the assist gas G is formed between the nozzle 3 and the steel plate W.
In the irradiation of the laser beam L2 from the laser torch 2, the injection of the assist gas G from the nozzle 3 is started, and at the same time as the piercing hole processing is started, the circulation control (circulation control means) of the laser torch 2 is started. (Step S3 in FIG. 3)

The laser beam L2 is applied to the steel plate W covered with the coating of the assist gas G, and heats and melts the steel plate W. By melting the steel plate W, a molten pool 60 is formed at the starting point of processing, and the molten material 64 is stored in the molten pool 60.
At this time, the melt 64 is oxidized and burned by the assist gas G and the assist gas G coating.

This melting and oxidation reaction is then continued until the piercing hole H is penetrated.
When the nozzle turning control is started, the laser torch 2 starts moving in accordance with an instruction from the processing unit 12b. (FIG. 3, step S4)
In the case of moving the circular movement locus 71, the distance from the machining starting point is offset by a distance corresponding to the radius of the circle that moves around the machining starting point. As shown in FIG. 4, the axis O1 of the laser torch is moved from the machining starting point. Eccentric piercing hole machining is performed. (Fig. 3, step S5 1))
Subsequently, a circular motion of a predetermined number of laps N is performed around the machining start point. (FIG. 3 step S52), 3))
Return to the starting point of machining again. (Fig. 3, step S5 4))

When moving along this circular movement locus 71, the axis O1 of the laser torch 2 is first moved and offset along the straight line 71a from the machining starting point within the range of the molten pool 60, and then the machining starting point along the circular locus 71b. Move around the circle.
The circular movement may be performed a plurality of times in accordance with the instruction of the processing unit 12b. When the circular movement is completed, the circular movement returns to the machining starting point along the straight line 71c.
In the case of a circular locus, the diameter d2 is preferably about 0.1 mm to 10 mm, for example.

During this time, the laser torch 2 injects the assist gas G from the nozzle 3 and continues to irradiate the laser beam L2, and the penetration of the piercing hole H is completed before the laser torch 2 returns to the processing starting point.
The relationship of the time T (SEC) required for the orbital movement of the laser torch 2, the number of revolutions N (times), the orbital movement speed V (mm / min), and the diameter d2 (mm) of the drawn circular locus are as follows:
T (sec) = ((d2) + πN (d2)) / (V / 60)
The T (sec) may be equal to or longer than the time required for the laser torch 2 to penetrate the piercing hole H of the steel sheet W having a thickness t (mm).
In this embodiment, the offset amount is the radius (d2) / 2 of the circular locus.

The center axis O1 of the nozzle 3 of the laser torch 2, that is, the center axis OG of the pressure distribution of the assist gas G is offset from the processing start point and moved around the processing start point, as shown in FIGS. 6A and 6B. The central axis OG of the pressure distribution of the assist gas G is offset from the machining starting point that is the center of the opening 61 of the molten pool 60, and as a result, the pressure distribution of the assist gas G is concentric with the machining starting point that is the center of the molten pool 60. As a result, there is an asymmetrical bias at the starting point of machining, and the pressure balance of the assist gas G at the opening 61 of the molten pool 60 is biased to generate a high pressure portion 61s and a low pressure portion 61w.
FIG. 7 shows an example of the pressure distribution of the assist gas G having a pressure at the center of the pressure distribution of about 0.0255 (MPa). Even in this pressure distribution, the axis O1 of the laser torch 2 and For example, when the processing starting point is offset by 0.25 mm, a pressure difference of 0.0015 MPa is generated.

  When the pressure distribution of the assist gas G is concentric with the processing starting point that is the center of the molten pool 60, the pressure of the assist gas G acts like a lid of the molten pool 60, so that the melt 64 is contained in the molten pool 60. The pressure distribution balance of the assist gas G is biased and the high pressure portion 61s and the pressure pulling portion 61w are generated, so that the molten gas is melted depending on the position of the opening 61 of the molten pool 60. It is considered that there is a large difference in the pressure applied to the object 64, the melt 64 is moved from the 61s side to the 61w side, and the discharge outside the molten pool 60 is promoted. The discharged melt 64 adheres to the surface of the steel plate W as a deposit 65 such as dross.

  As a result, while the assist gas G is offset from the processing starting point that is the center of the molten pool 60 (including the offset during the circular movement), the storage of the melt 64 in the molten pool 60 is suppressed, and excessively. By suppressing the oxidation reaction and combustion, it is presumed that the diameter expansion of the piercing hole H is suppressed and the small diameter piercing hole H can be formed.

In addition, since the laser torch 2 moves around the processing start point, the melt 64 discharged from the molten pool 60 is dispersed and discharged around the molten pool 60, and thus is discharged from the discharged melt 64. Heat does not concentrate in one place, local overheating and excessive oxidation reaction to the steel plate W around the piercing hole H are suppressed, and expansion of the piercing hole diameter d1 is suppressed.
As a result, even when laser light is continuously irradiated, piercing holes with high hole diameter accuracy can be easily and reliably formed while ensuring high productivity by continuous irradiation.

In the above-described embodiment, the case of the circular movement locus drawn by the laser torch 2 around the machining start point is the circular movement locus 71 including a circle, but the locus drawn by the laser torch 2 is a straight line as shown in FIG. 5B. 72a is offset from the machining start point along 72a, and then moves along a straight line 72b, 72c, 72d while drawing a triangle. After the circular movement (which may be a plurality of times) is completed, the machining is performed along the straight line 72e. It may be a circular movement locus 72 including a triangle returning to the starting point.
Further, as shown in FIG. 5C, the laser torch 2 is offset from the machining starting point along the straight line 73a, and then moves along a straight line 73b, 73c,. It is also possible to apply a circular movement locus 73 including a polygon that returns to the machining start point along the straight line 73n + 2 after the circular movement (which may be a plurality of times) is completed.

  Further, as shown in FIG. 8, the locus drawn by the laser torch 2 is offset from the machining start point along the straight line 75a, and then reciprocated with the stroke of st1 like the straight lines 75b, 75c, 75d, or such reciprocation. It is also possible to use a movement trajectory 75 including reciprocating movement that moves while drawing a trajectory including movement.

Further, as shown in FIG. 9, the locus drawn by the laser torch 2 is offset from the machining starting point along the straight line 76a, and then reciprocated along the straight lines 76b, 76c,. It is also possible to apply a movement trajectory 76 that moves in a zigzag that moves with a movement amount M per reciprocation in a direction orthogonal to the reciprocating direction.
In the zigzag movement, for example, when the movement per reciprocation is a predetermined angle other than 90 ° in the reciprocating movement direction, it is possible to move to a Z shape.
As described above, when the laser torch 2 is moved by the movement locus 75 including the reciprocating movement or the movement locus 76 that moves in a zigzag manner, the laser torch 2 is not necessarily required to return to the position corresponding to the machining start point.

  According to the laser piercing method and the processing apparatus 1 according to the above-described embodiment, the laser torch 2 is offset from the processing start point and moves around while drawing a circular locus, for example, thereby assisting the opening 61 of the molten pool 60. The molten material 64 in the molten pool 60 is moved from the portion 61 s where the pressure of the gas G is high to the portion 61 w where the momentum of the assist gas G is low. As a result, the molten material 64 of the molten pool 60 moves in the circumferential direction of the molten pool 60. Dispersed and discharged, the molten material 64 in the molten pool 60 is discharged in a short time, and as a result, the oxidation of the molten material 64 can be suppressed and the piercing hole diameter d1 can be reduced.

[Oxygen concentration control unit]
First, the processing unit 12b receives data related to a plate thickness t (processed portion thickness t) and a piercing hole diameter d1 for performing the piercing hole processing of the steel plate W from the plate thickness input unit 31a and the piercing hole size input unit 31b.
It is determined whether or not the oxygen concentration C of the assist gas G injected from the nozzle 3 needs to be adjusted based on the input thickness t of the steel plate W and the piercing hole diameter d1. The oxygen concentration C of the assist gas G is determined by the following equations (1) to (3) corresponding to the plate thickness t.
The oxygen concentration C is
In the range of 0 <t <8 mm,
0 <C <99.9 (1)
In the range of 8 ≦ t <13.5 mm,
0 <C ≦ −1.65t + 111.2 (2)
In the range of 13.5 ≦ t ≦ 26.33 mm,
5.28t−71.28 ≦ C ≦ −1.65t + 111.2 (3)
C: oxygen concentration (Vol%), t: plate thickness of steel plate W (mm)

Further, if necessary, an instruction regarding the injection pressure P of the assist gas G injected from the nozzle 3 may be input from the pressure mode input unit 31d, and the piercing hole is based on the equations (1) to (3). In performing the processing, the assist gas injection pressure P for processing the piercing hole,
In the range of 0 <t <13 mm, 0.015 ≦ P ≦ 0.05 (4)
In the range of 13 ≦ t ≦ 26.33 mm,
0.002t−0.011 ≦ P ≦ 0.002t + 0.024 (5)
And is preferred to
Also, the assist gas injection pressure P is
In the range of 0 <t <13 mm, P = 0.03 (6)
In the range of 13 ≦ t ≦ 26.33 mm,
P = 0.002t + 0.004 (7)
P: Assist gas G injection pressure (MPa), t: Steel plate W thickness (mm)
Then, the molten material 64 in the molten pool 60 is discharged almost completely, which is optimal for reducing the piercing hole diameter d1.

  Next, the processing unit 12b obtains the opening data of the mass flow controllers 27a and 27b corresponding to the oxygen concentration of the assist gas G calculated (calculated) by the above formula, and the pressure for obtaining the calculated injection pressure P of the assist gas G. Control data of the regulating valve 25 is acquired from the data table 13 via the signal cable 14 and transmitted to the mass flow controllers 27a, 27b and the pressure regulating valve 25 via the signal cables 26a, 26b, 28, respectively.

The mass flow controllers 27a and 27b are controlled to open and close the flow path according to the opening degree data transmitted from the processing unit 12b, and the amounts of oxygen and nitrogen necessary to generate the assist gas G having a desired oxygen concentration, The mixture is supplied from the oxygen supply source 41 and the nitrogen supply source 43 to the mixer 24.
A predetermined amount of oxygen and nitrogen supplied to the mixer 24 are mixed by the mixer 24 to be an assist gas G having a predetermined oxygen concentration, supplied to the nozzle 3, and injected to the steel plate W from the injection port 3 b of the nozzle 3. At the same time, the laser beam L2 is applied to the steel plate W to perform piercing.
In this case, the piercing hole H can be formed with high efficiency by adjusting the oxygen concentration of the assist gas G so that excessive oxidation and combustion do not occur even in continuous irradiation with the laser beam L2 instead of pulse irradiation. .
In this case, the pressure adjustment valve 25 is controlled by the control data transmitted from the processing unit 12b, and the assist gas G supplied to the nozzle 3 is set to a desired injection pressure P.

According to the laser piercing method and the processing apparatus 1 according to the above embodiment, the oxygen concentration C of the assist gas G injected from the nozzle 3 is determined according to the plate thickness t of the steel plate W, which is the steel plate W, and the oxygen Since the piercing hole processing is performed at the concentration C, excessive oxidation and combustion of the steel sheet W are suppressed, and the amount of dross is reduced. Therefore, the thickness of each steel sheet W has a smaller diameter in terms of material yield and quality. The piercing hole H can be easily and reliably formed.
In addition, by adjusting the oxygen concentration of the assist gas G, even when laser light is continuously irradiated, excessive oxidation and combustion are suppressed, and while maintaining high productivity by continuous irradiation, the pore diameter is reduced. A small piercing hole can be formed easily and reliably.

[Dross removal control unit]
First, it is determined whether or not the dross removing operation is performed after the piercing hole processing. If necessary, the dross removing operation is selected after the piercing hole processing, and an instruction is input to the dross removal mode input unit 31e.
The signal input from the dross removal mode input unit 31e is transmitted to the processing unit 12c via the data cable 33e.
The processing unit 12c transmits the data regarding the plate thickness t and the piercing hole diameter d1 of the steel plate W transmitted from the plate thickness input unit 31a and the piercing hole size input unit 31b to the data table 13c, and the hole diameter of the piercing hole H to be processed. And the data regarding the position and operation | movement of the nozzle 3 suitable for dross removal of the piercing hole H are received from the data table 13c.

Examples of the data regarding the position and operation that the processing unit 12c receives from the data table 13c include the distance from the axis OH of the piercing hole H and the height from the surface of the steel plate W, the circumferential movement speed of the nozzle, the number of circulations, and the circular movement locus. (Including information on the distance from the peripheral edge of the shaft edge OH or the piercing hole H) and the like.
The processing unit 12c calculates time / position information for moving the driving member 80 based on these data received from the data table 13c, and the calculation result is transmitted via the signal cables 15a, 15b, and 15c. The data is transmitted to the X driver 16a, Y driver 16b, and Z driver 16c to drive each driver.
The X driver 16a, the Y driver 16b, and the Z driver 16c move the laser torch 2 by driving the driving member 80.

The operation order is as follows.
The laser torch 2 is arranged at a predetermined position, for example, at the machining start point.
The dross removal control is automatically activated following the piercing hole machining in the automatic operation. The dross removal control may be performed manually by turning on the start switch.
The laser torch 2 is raised to a predetermined height by the Z driver 16c.
Next, the laser beam L 2 is emitted from the laser torch 2, and the assist gas G is ejected from the nozzle 3.
Here, the raising of the laser torch 2, the irradiation with the laser light L2, and the injection of the assist gas G may be performed simultaneously.

Next, the drive member 80 is driven by the X driver 16a and the Y driver 16b to move the laser torch 2 to a position where the axis O1 is a predetermined distance from the periphery of the piercing hole H.
Next, the driving member 80 is driven by the X driver 16a and the Y driver 16b to move the laser torch 2 around the surface of the steel plate W around the piercing hole H, while heating the dross accumulated by the laser light L2. At the same time, the dross is melted and oxidized and burned by the assist gas G, and the melted and oxidized dross is removed by the assist gas G.
If it moves around the processing starting point for a predetermined number of times, the irradiation of the laser beam L2 and the injection of the assist gas G are terminated, and the process returns to the processing starting point to complete the dross removal control.

In the above embodiment, the data relating to the flow rate and pressure of the assist gas G are stored in the data table 13c, but may be calculated in the processing unit 12c.
Further, the axis O1 of the laser torch 2 with respect to the piercing hole H is usually from the periphery of the piercing hole H, for example, radially outward from 0 (corresponding to the periphery of the piercing hole H) to the surface of the steel plate W at a position of 3.0 mm or less. The upper part of is preferable.
In the case of continuous irradiation laser output 6 kW, steel plate W plate thickness t22 mm,
The height of the nozzle 3 from the surface of the steel plate W: 50 mm, the assist gas pressure: 0.1 MPa, the position of the circular locus drawn by the axis O1 of the laser torch 2: the piercing hole with respect to the piercing hole with the piercing hole diameter d1 = 4.5 mm When the axis O1 was moved to a position with a radius of 4.25 mm from the axis OH, that is, 2 mm outward in the radial direction of the diameter of the piercing hole, a good result was obtained.

According to the laser piercing method and the processing apparatus 1 according to the above embodiment, after the piercing hole H penetrates, the nozzle 3 is moved above the surface of the workpiece around the piercing hole H and irradiated with laser light. The accumulated dross is remelted so that it is easily peeled off from the surface of the workpiece W. Further, the dross is easily burned, and moves around the piercing hole H while injecting the assist gas G from the nozzle 3. Therefore, the dross formed on the surface of the workpiece near the opening of the piercing hole H around the piercing hole H can be easily and efficiently removed, and as a result, the high quality piercing hole H is processed. Can do.
Further, since the nozzle 3 is moved around the piercing hole H and the assist gas G is injected from a short distance with respect to the dross, the dross can be reliably removed at a small flow rate. Processing time and processing cost can be greatly reduced.

In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention.
In the above embodiment, the case of continuous irradiation in which the steel plate W is continuously irradiated with the laser beam L has been described. However, the laser beam L to be irradiated may be pulse irradiation, and in particular, pulse irradiation with a duty of 90% or more. In, substantially the same effect as in the case of continuous irradiation can be obtained.

  Further, in the above-described embodiment, the case where the oxygen concentration adjustment of the assist gas G is combined with the rotation control of the laser torch 2 has been described, but the movement control of the laser torch 2 and the oxygen concentration adjustment of the assist gas G have been described. The combination conditions can be freely set.

  In the above embodiment, the case where the laser torch 2 moves in a circle around the center of the piercing hole has been described. However, the shape drawn by the tip of the laser torch 2 is not limited to a circle, but a triangle, It can also be a polygon such as a rectangle.

In the said embodiment, although the case where the workpiece W was a steel plate was demonstrated, the workpiece W applied to the method and the processing apparatus 1 which concern on this invention is restricted to the board | plate material with uniform thickness t. Alternatively, the processed part may have a thickness t different from that of the periphery thereof, or may be made of another metal such as stainless steel, aluminum, copper, titanium, or an alloy thereof.
Further, as part of the gas constituting the assist gas G, an inert gas such as argon or helium can be used.

  In addition, although (1) to (3) are shown as mathematical formulas for specifying the oxygen concentration C of the assist gas G, the processing apparatus 1 has a control pattern based on mathematical formulas other than this mathematical formula and is applied to piercing hole machining. May be. In addition, the oxygen concentration and the injection pressure P are controlled by a scale provided on the mass flow controllers 27a, 27b, etc., or an opening adjusting device using gears, a link mechanism, etc. May be.

  Further, in the above embodiment, the trajectory drawn by the laser torch 2 and the number of laps corresponding to the thickness t of the workpiece W based on the data such as the thickness t input to the machining data input unit 30. The processing unit 12 calculates the control data from the data table 13 and moves the laser torch 2. However, based on the input information such as the plate thickness t, the processing unit 12 a obtains the control data. It is also possible to directly calculate and move the laser torch 2 according to the result.

  The case where the oxygen concentration of the assist gas G is calculated by the processing unit 12b and control data is acquired from the data table 13b to control the mass flow controllers 27a and 27b has been described. However, based on the input information such as the thickness t Thus, the control data may be directly calculated to adjust the oxygen concentration C and the injection pressure P.

Here, the verification test about the effect of the piercing hole processing which concerns on one embodiment of this invention was implemented.
FIG. 10 shows the verification results when the circular movement locus drawn by the laser torch 2 around the machining start point is a circular movement locus 71 including a circle. F, J, and K are Comparative Examples 1, respectively. Example 1 and Example 2 are shown, and a steel plate having a thickness of 6 mm, 9 mm, 12 mm, 16 mm, and 19 mm is irradiated with laser light by a laser processing machine, and assist gas is injected from a nozzle to pierce holes. The relationship between the plate thickness t (mm) of the steel plate W and the piercing hole diameter d1 (mm) is shown.
The processing conditions of the laser processing machine are as follows.
(1) Irradiation form and output of laser processing machine; continuous irradiation, 2.5 kW
(2) Distance from steel plate W to nozzle opening; 6 mm
Are common to Example 1, Example 2, and Comparative Example 1.
In Example 1, after starting the piercing hole machining on the steel plate, the axis O1 of the laser torch 2 is offset from the machining starting point, and then the circular movement is drawn around the machining starting point by a predetermined number of times N (times). The piercing holes were machined again by returning to the machining starting point.
In Example 2, in addition to the processing conditions of Example 1, the oxygen concentration C of the assist gas G was adjusted to 52.6 (vol%) to process the piercing holes.
In the comparative example, the piercing hole was processed while the axis O1 of the nozzle 3 was made to coincide with the processing start point even after the processing of the piercing hole H was started.
In addition, the processing conditions varied depending on the thickness t of the steel sheet are as follows. Here, the speed of the torch, the number of laps, and the diameter d2 of the circular locus are the conditions related to Example 1 and Example 2. is there.
〔Processing conditions〕
Steel sheet thickness t Torch speed Number of laps Circular trajectory diameter Assist gas pressure 6mm 1500mm / min 1 time 0.5mm 0.04MPa
9mm 500mm / min 2 times 2.0mm 0.04MPa
12mm 500mm / min 5 times 4.0mm 0.04MPa
16mm 1500mm / min 5 times 4.0mm 0.23MPa
19mm 1500mm / min 5 times 4.0mm 0.23MPa

〔inspection result〕
The piercing hole diameter d1 processed under the above processing conditions is as follows.
Thickness t of steel plate Example 1 Example 2 Comparative example 1
6mm 2.2mm 2.2mm 4.1mm
9mm 3.3mm 3.2mm 4.4mm
12mm 3.4mm 3.3mm 4.8mm
16mm 7.1mm 4.5mm 8.7mm
19mm 6.5mm 5.2mm 9.7mm

As described above, in both Example 1 and Example 2, effects were confirmed with respect to Comparative Example 1 in any of the steel plate thicknesses of 6 mm, 9 mm, 12 mm, 16 mm, and 19 mm.
In addition, when Example 2 and Example 1 are compared, Example 2 has a small change in the range where the plate thickness t is 6 mm to 12 mm, but the plate thickness t is 16 mm and 19 mm. There was a large change (the reduction ratio was about 37% at the maximum), and it was confirmed that there was a further effect by adjusting the oxygen concentration of the assist gas.

Similarly, verification results for a steel plate having a thickness of 22 mm are shown below.
The processing conditions of the laser processing machine are as follows.
(1) Irradiation form and output of laser processing machine; continuous irradiation, 6.0 kW
(2) Distance from steel plate W to nozzle opening; 4 mm
Is common to Example 3, Example 4, and Comparative Example 2, and the processing conditions are the same as those of Example 1, Example 2, and Comparative Example 1, the speed of the torch; 150 mm / min, the number of turns; Twice, the diameter d2 of the circular locus was 0.5 mm, and the assist gas pressure was 0.04 MPa.

〔inspection result〕
The piercing hole diameter d1 processed under the above processing conditions is as follows.
Thickness t of steel plate Example 3 Example 4 Comparative example 2
22mm 6.2mm 4.5mm 7.6mm

As described above, both Example 3 and Example 4 were confirmed to be effective with respect to Comparative Example 2.
Further, there was a large change (reduction rate of about 28%) in the comparison between Example 4 and Example 3, and it was confirmed that there was a further effect by adjusting the oxygen concentration of the assist gas.

Next, in this embodiment, a verification result when the laser torch 2 processes the piercing hole while moving the moving locus 75 including the reciprocating movement and the zigzag moving locus with respect to the steel plate having a thickness of 22 mm is shown. The case where the laser torch 2 is moved as shown in the movement locus 75 is the fifth embodiment, and the case where the laser torch 2 is moved as shown in the movement locus 76 is the sixth embodiment.
The processing conditions of the laser beam machine in Example 5 and Example 6 are as follows.
(1) Irradiation form and output of laser processing machine; continuous irradiation, 6.0 kW
(2) Distance from steel plate W to nozzle opening; 6 mm
(3) Torch speed: 600 mm / min, assist gas pressure: 0.35 MPa
(3) The trajectory including the reciprocating movement of the laser torch 2 in Example 5 is the reciprocating stroke st1; 0.5 mm, the number of reciprocations: 5 times. (4) The zigzag moving trajectory of the laser torch 2 in Example 6 is the reciprocating direction. Stroke st2: 0.5 mm, number of reciprocations: 5 times, movement amount M per reciprocating movement of the direction component orthogonal to the reciprocating movement direction: 0.2 mm
In Comparative Example 2, those according to Example 3 and Example 4 described above were used.

〔inspection result〕
The piercing hole diameter d1 of Example 5 under the above processing conditions is
Thickness t of steel plate Example 5 Comparative example 2
22mm 3.5mm 7.6mm
And also
The piercing hole diameter d1 of Example 6 under the above processing conditions is
Thickness t of steel plate Example 6 Comparative example 2
22mm 3.5mm 7.6mm
It is.
As described above, it was confirmed that Example 5 and Example 6 have a great effect over Comparative Example 2.

It is a figure which shows the ashing hole process which concerns on one embodiment of this invention, and is a figure which shows the case where a nozzle exists in a process starting point. It is a figure which shows the outline of a structure of the processing apparatus which concerns on one embodiment of this invention. It is a figure which shows the flow of the piercing hole processing which concerns on one embodiment of this invention. It is a figure which shows the case where a nozzle is offset in the laser piercing process which concerns on one embodiment of this invention. FIG. 5A is a diagram showing a trajectory of a laser torch according to an embodiment of the present invention, FIG. 5A is a case of a moving trajectory including a circle, FIG. 5B is a case of a moving trajectory including a triangle, and FIG. The case of a moving trajectory including is shown. It is a figure which shows the pressure distribution of assist gas when the nozzle which concerns on one embodiment of this invention is offset from the center of a molten pool, FIG. 6A is a top view, FIG. 6B is a side view. It is a figure which shows the pressure distribution of the assist gas which concerns on this invention. It is a figure which shows the movement locus | trajectory of the laser torch which concerns on one embodiment of this invention, and is an example in case a nozzle moves the locus | trajectory containing a reciprocation. It is a figure which shows the movement locus | trajectory of the laser torch which concerns on one embodiment of this invention, and is an example in case a nozzle moves zigzag. It is a figure which shows the effect of the piercing hole processing which concerns on one embodiment of this invention. It is a figure which shows the outline of the nozzle part of the conventional laser cutting machine.

Explanation of symbols

H Piercing hole L1, L2 Laser beam t Thickness (thickness of processed part)
OH Piercing hole axis G Assist gas W Steel plate (metal workpiece)
C Oxygen concentration 1 Processing device 2 Laser torch 3 Nozzle 10 Piercing control unit (control means)
11 Nozzle movement control unit 20 Oxygen concentration adjusting unit (oxygen concentration adjusting means)
40 Dross removal control unit (Dross removal means)
60 molten pool 64 molten material

Claims (12)

While irradiating the processing portion of the workpiece with laser light, the assist gas is sprayed from the nozzle arranged coaxially with the laser light toward the processing portion, and the processing portion is covered with the assist gas. A laser piercing method for machining a piercing hole,
A laser piercing method characterized by processing a piercing hole while moving the nozzle within a range of 5 mm from the processing starting point after the start of irradiation with the laser beam. The laser piercing method according to claim 1,
The nozzle,
A laser piercing method characterized by moving around a processing starting point. The laser piercing method according to claim 1,
The nozzle,
A laser piercing method, wherein the laser piercing is performed along a trajectory including reciprocal movement. The laser piercing method according to claim 1,
The nozzle,
A laser piercing method characterized by moving in a zigzag manner. A laser piercing method according to any one of claims 1 to 4,
The oxygen concentration C of the assist gas injected from the nozzle is determined in accordance with the thickness t of the processing part that performs the piercing hole processing,
The oxygen concentration C is
In the range of 0 <t <8 mm, 0 <C <99.9
In the range of 8 ≦ t <13.5 mm, 0 <C ≦ −1.65t + 111.2
In the range of 13.5 ≦ t ≦ 26.33 mm,
5.28t−71.28 ≦ C ≦ −1.65t + 111.2
C: oxygen concentration (Vol%), t: thickness of processed part (mm)
A laser piercing method characterized in that: A laser piercing method according to any one of claims 1 to 5,
After penetrating the piercing hole, the nozzle is moved above the surface of the workpiece around the piercing hole, the laser beam is irradiated to remelt the dross and the assist gas is injected from the nozzle. A laser piercing method characterized by removing the dross formed around the piercing hole by moving around the piercing hole. While irradiating the processing portion of the workpiece with laser light, the assist gas is sprayed from the nozzle arranged coaxially with the laser light toward the processing portion, and the processing portion is covered with the assist gas. A processing device for processing a piercing hole,
A processing apparatus comprising: control means for processing the piercing hole while moving the nozzle within a range of 5 mm from the processing starting point after the start of irradiation with the laser beam. The processing apparatus according to claim 7,
The control means includes
A processing apparatus comprising a rotation control means for moving the nozzle around the processing start point. The processing apparatus according to claim 7,
The control means includes
A processing apparatus comprising a reciprocating control means for moving the nozzle along a trajectory including reciprocating movement. The processing apparatus according to claim 7,
The control means includes
A processing apparatus comprising zigzag control means for moving the nozzle in a zigzag manner. The processing apparatus according to any one of claims 7 to 10,
The control means includes
A processing apparatus comprising oxygen concentration adjusting means for determining an oxygen concentration C of the assist gas injected from the nozzle in accordance with a thickness t of a processing portion that performs the piercing hole processing. The processing apparatus according to any one of claims 7 to 11,
The control means includes
After penetrating the piercing hole, the nozzle is moved above the surface of the workpiece around the piercing hole, the laser beam is irradiated to remelt the dross and the assist gas is injected from the nozzle. A processing apparatus comprising dross removing means for moving around the piercing hole and removing dross formed around the piercing hole.

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