WO2012063668A1

WO2012063668A1 - Laser machining method and laser machining device

Info

Publication number: WO2012063668A1
Application number: PCT/JP2011/075039
Authority: WO
Inventors: 増田　健司
Original assignee: 株式会社アマダ
Priority date: 2010-11-09
Filing date: 2011-10-31
Publication date: 2012-05-18
Also published as: JP2012115899A

Abstract

In this laser machining method, which performs laser cutting of a steel sheet along a closed path, when the position of the closed path to be cut reached from a piercing machining position is position A, a position that is a predetermined distance in the direction of process of cutting machining from position A is position B, and a position that is a predetermined distance in the reverse direction with respect to the direction of process from position A is position C, during cutting machining from position C through position A to position B after cutting machining from position A through position B to position C, cutting machining is performed from position C through position A to position B at a lower laser output and a slower cutting speed compared to the laser output and cutting speed from position A through position B to position C, and the laser output is caused to be zero at position B. By means of the laser machining method, it is possible to increase machining efficiency without causing the formation of pits or the adherence of molten material to the inner peripheral surface of the cut closed path when laser cutting a work along a closed path.

Description

Laser processing method and laser processing apparatus

The present invention relates to a laser processing method and a laser processing apparatus for cutting a steel plate into an annular shape with a laser.

When cutting a steel sheet (workpiece) with a laser along a closed path [closed path], a laser beam is radiated to the processing position of the work and an assist gas is injected. The cut-out piece [blanked] piece] may be inclined at the processing end position, and the inclined cut-out piece is melted by the laser and the melt adheres to the inner peripheral surface of the cut-out hole [blanked hole], or the inclined cut-out piece As a result, the laser beam is reflected and the inner peripheral surface is melted to form a recess (for example, Patent Document 1 or 2 below).

Patent Document 1 discloses an apparatus (method) for performing a secondary process of cutting and removing a projecting part after performing a primary process of cutting a workpiece so as to form a projecting part on an inner peripheral surface of a cutout hole. ing. Here, since the primary processing described above is completed at the position of the protrusion, adhesion of the melt to the inner peripheral surface and formation of the recess are formed in the protrusion that will be cut off later. Accordingly, it is possible to finally prevent the melt from being attached to the inner peripheral surface of the cut-out hole and the formation of a recess.

In Patent Document 2, laser cutting is started from the start position, cutting is performed along the closed path, the cutting start position is returned again, and the cutting start position is passed by a distance corresponding to the melting delay of the lower surface with respect to the upper surface of the workpiece. An apparatus (method) for sometimes stopping laser irradiation is disclosed. Since the laser irradiation is stopped when the cutting of the melting delay portion is completed, the adhesion of the melt and the formation of the concave portion on the inner peripheral surface as described above are suppressed.

Japanese Unexamined Patent Publication No. 2004-122217 Japanese Unexamined Patent Publication No. 2006-218535

However, in the apparatus of Patent Document 1 described above, melt adhesion to the inner peripheral surface of the cut-out hole and formation of a concave portion can be prevented, but secondary processing for removing the protruding portion is necessary, so that processing ease and processing efficiency are improved. There was a problem in terms of sex. Further, in the apparatus of Patent Document 2 described above, since the laser cutting is performed twice during the distance corresponding to the melting delay, the cutting slit width may be widened, and further improvement has been desired.

Accordingly, an object of the present invention is to produce a product without causing adhesion of melt or formation of recesses on the inner peripheral surface of the cut closed path when the workpiece is laser cut along the closed path. It is an object to provide a laser processing method and a laser processing apparatus that can improve efficiency.

A first feature of the present invention is a laser processing method in which oxygen gas is used as an assist gas to perform laser cutting along a closed path of a steel sheet, and the position reached from the piercing position to the closed path to be cut Is a position A, a position a predetermined distance from the A position in the advancing direction of the cutting process is a B position, and a position a predetermined distance from the A position to the direction opposite to the advancing direction is a C position. Laser cutting and cutting from the A position through the B position to the C position at the time of cutting from the C position to the B position through the A position after cutting from the position to the C position through the B position The laser output is reduced with respect to the speed, and the cutting speed is lowered to perform the cutting process from the C position to the B position through the A position, and the laser output is made zero at the B position. To provide a factory method.

According to the above feature, when cutting a closed path on the workpiece, the laser output is controlled to be small and the cutting speed is controlled to be low before reaching the start position after starting laser cutting. Therefore, even when the cutting position reaches the start position again and the cutout piece is inclined, the irradiation energy of the laser light is reduced, so that adhesion of the melt to the inner peripheral surface and formation of the recess can be suppressed.

Here, it is preferable to switch the assist gas to air, nitrogen gas, or a mixed gas in which at least one of air or nitrogen gas is mixed with oxygen gas at the position C.

The second feature of the present invention is a laser processing apparatus, a laser oscillator, a laser processing head for condensing laser light and irradiating a work, and an assist gas supply unit for supplying an assist gas to the laser processing head A control unit that controls a laser output of the laser oscillator and a relative moving speed of the laser processing head with respect to the workpiece, and the laser cutting along the closed path by using oxygen as an assist gas. A machining condition table that stores in advance machining conditions in the cutting end region of the closed path corresponding to the material and thickness of the workpiece, and a machining that is applied from the machining condition table corresponding to the material and thickness of the workpiece to be machined A search unit that searches for a condition, and the control unit is configured to search for a previous position in the cutting end region based on a search result of the search unit. Controlling the laser output and the moving speed, to provide a laser machining apparatus.

According to the above feature, when cutting the closed path on the workpiece, the laser output and the cutting speed in the cutting end region of the closed path are controlled by the control unit. Therefore, even if the cutting position reaches the start position again and the cut piece is inclined, the laser beam irradiation energy can be controlled to suppress the adhesion of the melt to the inner peripheral surface and the formation of the recess.

The third feature of the present invention is a laser processing apparatus, a laser oscillator, a laser processing head for condensing laser light and irradiating a work, and an assist gas supply unit for supplying an assist gas to the laser processing head A control unit for controlling the laser output of the laser oscillator and the relative moving speed of the laser processing head with respect to the workpiece, and when cutting the laser along the closed path using oxygen as an assist gas A memory for storing the processing conditions in the cutting end region of the closed path in correspondence with the material and thickness of the workpiece, and an input unit for inputting the processing conditions in the cutting end region to the memory. The control unit, based on the processing conditions in the cutting end area input to the memory, the cutting end area in the cutting end area Controlling the over The output and the moving speed, to provide a laser machining apparatus.

According to the above feature, when cutting the closed path on the workpiece, the laser output and the cutting speed in the cutting end region of the closed path are controlled by the control unit based on the input processing conditions. Therefore, even if the cutting position reaches the start position again and the cut piece is inclined, the laser beam irradiation energy can be controlled to suppress the adhesion of the melt to the inner peripheral surface and the formation of the recess.

It is a schematic block diagram which shows the main structures of the laser processing apparatus which concerns on embodiment. It is a functional block diagram of the control part of the said processing apparatus. It is explanatory drawing of the cutting process of the closed path | route. It is a top view which shows a product shape. It is explanatory drawing of the example of process data which shows the shape, dimension, and coordinate for the process of the said product shape. It is a flowchart of a laser cutting process. It is a flowchart (modification) of laser cutting processing.

As shown in FIG. 1, the laser processing apparatus 1 of the present embodiment cuts a thick steel plate (workpiece) W having a plate thickness of about 16.0 mm to 25.0 mm, for example. The laser processing apparatus 1 includes a laser processing head 7 that condenses the laser beam LB oscillated from the laser oscillator 3 by a built-in condensing lens 5 and irradiates the workpiece W. The laser processing head 7 is movable relative to the workpiece W in the X, Y, and Z axis directions. An assist gas supply unit 9 for injecting an assist gas to the workpiece W at the time of laser cutting of the workpiece W is connected to the laser processing head 7.

The assist gas supply unit 9 includes an oxygen supply unit [oxygen supplier] 11 such as an oxygen cylinder storing high-purity oxygen of 99.99% or more as an assist gas and a nitrogen gas supply unit [nitrogen] that supplies a nitrogen gas as an assist gas. gad supplier] 13. Furthermore, the assist gas supply unit 9 is also provided with an air supply unit [air supplier] 15 for supplying air as assist gas. The oxygen supply unit 11, the nitrogen gas supply unit 13, and the air supply unit 15 are connected to the connection path 17 of the laser processing head 7 via

control valves

11V, 13V, and 15V, respectively. The

control valves

11V, 13V, and 15V are, for example, known electromagnetic proportional valves. The

control valves

11V, 13V, and 15V can communicate / shut off the gas flow through the connection path 17, and can control the flow rate of the gas flow.

By controlling the

control valves

11V, 13V, and 15V, oxygen, nitrogen gas, or air can be individually supplied as an assist gas, and a mixed gas in which two or more of oxygen, nitrogen gas, and air are mixed can also be supplied. it can.

The laser processing apparatus 1 controls the operation of the output of the laser oscillator 3, the servo motors M for moving the laser processing head 7 in the X, Y, and Z axis directions, and the

control valves

11V, 13V, and 15V. A controller 19 is provided. The control unit 19 is, for example, a CNC control device, and includes a CPU 20, a ROM 21, a RAM 23, an input unit [input part] 25, a display unit [display] 27, and a memory 39 as shown in FIG. 2. Furthermore, the control unit 19 also includes a machining condition table 29 that stores machining conditions for a cutting end region, which will be described later. Note that the processing condition table 29 may be stored in the ROM 21, RAM 23, memory 29, or the like.

As shown in FIG. 3, when oxygen is used as an assist gas and a thick workpiece (for example, about 16.0 mm to 25.0 mm) is cut along a circular path (closed path) L on a workpiece W, The A position that has reached the annular path L to be cut from the piercing position P corresponds to the laser cutting start position.

Then, a predetermined position that has advanced from the A position in the cutting direction (arrow R direction shown in FIG. 3) is defined as the B position. The distance between the A position and the B position is a distance corresponding to the melting delay of the lower surface (back surface) with respect to the upper surface (front surface) when cutting the workpiece W, and is appropriate by performing the cutting processing on a trial basis. A correct value is set. Further, a predetermined position that has advanced from the A position in the opposite direction to the aforementioned traveling direction is defined as a C position. The C position is set in advance corresponding to the material and thickness of the workpiece W, and is set to an appropriate position by performing a cutting process on a trial basis.

The machining condition table 29 includes a first machining condition table 29A and a second machining table 29B. The first machining condition table 29A includes general machining conditions (piercing time, laser cutting speed, output / frequency / duty of the laser oscillator 3) when cutting from the P position to the C position through the A position and the B position. Ratio, gas pressure of oxygen as an assist gas, etc.) are stored. On the other hand, in the second machining condition table 29B, machining conditions (laser cutting speed, output / frequency / duty ratio of the laser oscillator 3, duty ratio, etc.) when performing cutting from the C position as the cutting end region to the B position through the A position. Assist gas type / gas pressure, distance from A position to B position, distance from C position to A position, etc.) are stored. Therefore, if the material and thickness of the workpiece W are known, the machining conditions of the cutting end region of the workpiece W can be retrieved from the second machining condition table 29B.

The control unit 19 includes a retrieval unit [retriever] 31 for retrieving an appropriate machining condition from the machining condition table 29 corresponding to the material and thickness of the workpiece W input from the input unit 25 such as a keyboard. . The control unit 19 also has a laser output control unit 33 that controls the output of the laser oscillator 3 based on the processing conditions searched by the search unit 31, and a relative movement speed of the laser processing head 7 with respect to the workpiece W (laser cutting). A cutting speed control unit 35 for controlling the speed) and a valve control unit 37 for controlling the type and gas pressure of the assist gas of the assist gas supply unit 9.

When an annular cutting process is performed on a thick plate-shaped workpiece W using oxygen as an assist gas, the material and thickness of the workpiece W and processing data for cutting the product are input from the input unit 25. The For example, FIG. 5 shows processing data indicating the shape and coordinates of the product WA when the product is a product WA having a shape as shown in FIG. Here, the annular hole HA is circular, and (E001) designates the distance from C to A of the cutting end region. Further, (G112X15Y10I10L4) designates the processing content. Here, in the code (G112X15Y10I10L4), (G112) indicates a circle, (X15Y10) indicates a coordinate, and (I10) indicates a radius. Further, (L4) indicates that the machining conditions for the cutting end region are stored in the second machining condition table 29B.

Similarly, the hole HB has a polygonal shape, and (E002) designates the distance from C to A of the cutting end region. The code (G101X50Y10L4) designates the processing content. In the code (G101X50Y10L4), (G101) indicates a polygonal shape, and (X50Y10) indicates coordinates. Further, (L4) indicates that the machining conditions for the cutting end region are stored in the second machining condition table 29B. Similarly, (E003) and (G111X90Y30I40J25R3K-90L4) are designated for the hole HC. Regarding the cutting of the entire product WA, (E004) designates the distance C to A in the cutting end region. However, since it is the cutting process of the outer shape of the entire product WA, the specification of the processing condition of the cutting end region in (L4) is omitted.

The above-mentioned codes G111, G112, and G101 are codes set in advance corresponding to the shape of the hole when the hole is cut by the closed path. The above-mentioned E001, E002, E003, E004,... Are the machining condition change positions when the cut pieces in the holes HA, HB, HC from the product WA are cut off or the product WA is cut off from the workpiece W. This is a code for setting (C position: change position from normal machining condition to cutting end region machining condition). That is, preset E001, E002,... Are appropriately designated in accordance with the material and thickness of the workpiece W, and the shapes and dimensions of the holes HA, HB, HC and the product WA, and the A position from the C position. The dimension to the position is set.

The material and thickness of the workpiece W and the machining data input from the input unit 25 are stored in the memory 39 of the control unit 19. Then, an appropriate machining condition is retrieved from the first and second machining condition tables 29A and 29B of the machining condition table 29 by the search unit 31. The input value and input data, and the searched processing conditions are displayed on the display unit 27.

Specific explanation. For example, when SS400 is input as the material of the workpiece W and 19 mm is input as the thickness, the processing conditions in the normal region from the P position to the C position through the A and B positions are set to a cutting speed of 800 mm / min. The output 4000 W, the frequency 700 Hz, the duty ratio 70%, the selection of oxygen as the assist gas, and the gas pressure 0.07 MPa are retrieved from the first machining condition table 29A and set. Then, as processing conditions of the cutting end region from the C position through the A position to the B position, the cutting speed is 100 mm / min, the output of the laser oscillator 3 is 4000 W, the frequency is 5 Hz, the duty ratio is 40%, and the assist gas is nitrogen gas or air. Switching, gas pressure 0.70 MPa, distance from A position to B position 0.2 mm within the range of 0.1 mm to 1.0 mm, distance from C position to A position 0.5 mm to 3.0 mm Among them, 1.5 mm is retrieved from the second processing condition table 29B and set. Note that the distance from the A position to the B position and the distance from the C position to the A position are set as parameters (for example, C to A are E001, E002, etc.) and can be changed.

The laser output is controlled by the laser output controller 33 and the cutting speed is controlled by the cutting speed controller 35 so as to conform to the set value described above. Further, the type and gas pressure of the assist gas are also controlled so as to match the set value. Since the cutting process in the normal region from the P position to the C position through the A position and the B position is a cutting process using oxygen as an assist gas, the work W is not only generated by the irradiation energy of the laser beam LB but also by the oxidation reaction heat. Is promoted to melt. For this reason, for example, even a thick steel plate of 16.0 mm to 25.0 mm can be cut at high speed.

When the cutting process proceeds and reaches a preset C position, the cutting speed is controlled to a low speed based on the machining conditions retrieved from the second machining condition table 29B, and the laser output is reduced by reducing the frequency / duty ratio. It is controlled to be smaller. The irradiation energy at the time of cutting from the C position to the B position is smaller than the irradiation energy in the normal region according to the processing conditions retrieved from the first processing condition table 29A. When the laser output and the cutting speed are made zero at the B position and the cutting process is finished, the laser beam reflected by the inclined cutout piece S tends to be irradiated on the inner peripheral surface.

However, the irradiation energy of the laser beam reflected and applied to the inner peripheral surface is controlled to be small. Further, after the C position, the assist gas is switched from oxygen to nitrogen gas, air, or a mixed gas thereof by the valve switching control unit 37, so that the oxidation reaction of the workpiece W is also suppressed. For this reason, melt adhesion and recess formation on the inner peripheral surface can be suppressed. In addition, although it cut | disconnects twice from A position after passing C position to B position, since irradiation energy is controlled small as mentioned above and an oxidation reaction is also suppressed, cutting slit width | variety Is prevented from becoming wide.

The laser processing described above will be described with reference to the flowchart shown in FIG. First, it is determined whether or not the material and thickness of the workpiece W and the machining data (see FIG. 5) are input to the input unit 25 (step S10). If the material and thickness of the workpiece W and the machining data are not input (NO in step S10), the process in step S10 is repeated and the input is waited for. When the material and thickness of the workpiece W and the machining data are input (YES in step S10), the input value of the material and thickness of the workpiece W and the input data of the machining data are stored in the memory 39 (step S15). ).

Next, the above-described P, A, B, and C positions are determined based on the input value and the input data (step S20). As described above, the input machining data includes codes E001, E002, E003, E004,..., And P, A, B, and C positions are determined based on these codes. Based on the input value and the input data, the processing condition of the normal region is searched from the first processing condition table 29A by the search unit 31 and determined (step S25). Further, based on the input value and the input data, the processing conditions for the cutting end region are also retrieved from the second processing condition table 29B and determined (step S30). As described above, the input machining data includes a code that specifies to search the second machining condition table 29B by the code L4. The processing conditions in the cutting end region are set so that the cutting speed is controlled at a low speed and the laser output is reduced by reducing the frequency / duty ratio. The irradiation energy of the laser beam is higher than the irradiation energy in the normal region. Set small.

The determined machining conditions are also temporarily stored in the memory (step S35), and laser cutting is started according to the machining conditions determined by the control unit 19 (step S40). First, laser cutting in the normal region is performed according to the processing conditions determined in step S25 (step S45). During the laser cutting process in the normal region, it is determined whether or not the processing position has reached the C position (step S50). If the machining position has not reached the C position (NO in step S50), the process of step S50 is continued to continue the laser cutting process in the normal region.

On the other hand, when the processing position has reached the C position (YES in step S50), the processing conditions are changed to the processing conditions determined in step S30, and the process proceeds to laser cutting processing in the cutting end region (step S55). During the laser cutting process in the cutting end region, it is determined whether or not the processing position has reached the B position (step S60). If the machining position has not reached the B position (NO in step S60), the process of step S60 is continued to continue the laser cutting process in the cutting end region.

On the other hand, when the processing position has reached the B position (YES in step S60), the laser output is made zero (step S65) in order to end the laser cutting processing. If there are other laser cutting processes along the closed path, the processes in steps S45 to S65 are repeated based on the input process data and the determined process conditions.

In addition, this invention is not limited to embodiment mentioned above, It can implement also in another form by making an appropriate change. For example, in the above embodiment, the processing conditions of the cutting end region corresponding to the plate material and thickness of the workpiece W are stored in the processing condition table 29 in advance. However, the cutting end region processing conditions may be input from the input unit 25 to the memory 39, and the cutting end region may be cut under the input processing conditions.

The laser processing in this case will be described with reference to the flowchart shown in FIG. Note that the same processing steps as those of the laser processing shown in FIG. 6 described above are denoted by the same reference numerals and description thereof is omitted. Here, in addition to the material and thickness of the workpiece W and the machining data (see FIG. 5), the machining conditions in the cutting end region are also input to the input unit 25, so whether these are input to the input unit 25 or not. Determination is made (step S10A).

If these are not input (NO in step S10A), the process in step S10A is repeated to wait for input. When these are input (YES in step S10A), the input value of the material and thickness of the workpiece W, the input data of the processing data, and the processing conditions in the cutting end region are stored in the memory 39 (step S15A). Thereafter, after the processes in steps S20 and S25, the processing conditions of the input cutting end region are confirmed (step S30A). Note that the confirmation processing in step S30A may be omitted. Thereafter, the processes of steps S35 to S65 are executed.

Further, in the above embodiment, the laser beam irradiation energy is reduced by reducing the frequency and duty ratio while keeping the output of the laser oscillator 3 constant, but the output energy of the laser oscillator 3 is reduced and the irradiation energy is reduced. May be. That is, the laser beam irradiation energy in the cutting end region (the cutting region from the C position through the A position to the B position) is smaller than the laser beam irradiation energy in the cutting region from the A position through the B position to the C position. It suffices to be controlled.

As a method of controlling the irradiation energy of the laser beam in the cutting end region to be small, it is possible to reduce the irradiation energy at the time of cutting processing from the A position to the C position through the B position to a desired ratio. In this case, when the laser beam irradiation energy in the cutting region from the A position through the B position to the C position is 100%, the laser beam irradiation energy in the cutting end region is reduced to 10% to 50%. Is desirable. In particular, it is desirable that the laser power is reduced to 10% to 50% and the cutting speed is reduced to 10% or less.

In the above embodiment, the assist gas is switched from oxygen to nitrogen gas, air, or a mixed gas thereof in the cutting end region. However, a mixed gas obtained by mixing oxygen with at least one of nitrogen gas or air may be used as the assist gas, and the oxidation reaction heat can be suppressed even with such an assist gas.

Claims

A laser processing method in which oxygen gas is used as an assist gas and laser cutting is performed along a closed path of the steel sheet,
A position that reaches the closed path to be cut from the piercing position is defined as A position, a position that is a predetermined distance from the A position in the traveling direction of the cutting process is defined as B position, and the reverse direction from the A position to the traveling direction When the position at a predetermined distance is the C position, the cutting position from the C position to the B position through the A position to the B position after cutting from the A position to the C position through the B position. Cutting the laser output from the position through the B position to the C position and reducing the laser output relative to the cutting speed and reducing the cutting speed from the C position through the A position to the B position, A laser processing method in which the laser output is made zero at the B position.
2. The laser processing method according to claim 1, wherein at the position C, the assist gas is switched to air, nitrogen gas, or a mixed gas obtained by mixing at least one of air or nitrogen gas with oxygen gas. 3.
A laser processing apparatus,
A laser oscillator;
A laser processing head for condensing laser light and irradiating the workpiece;
An assist gas supply unit for supplying an assist gas to the laser processing head;
A controller that controls the laser output of the laser oscillator and the relative moving speed of the laser processing head with respect to the workpiece;
A machining condition table that stores in advance the machining conditions in the cutting end region of the closed path corresponding to the material and thickness of the workpiece when the workpiece is laser cut along the closed path using oxygen as an assist gas; ,
A search unit for searching for a machining condition to be applied from the machining condition table corresponding to the material and thickness of the workpiece to be machined,
The laser processing apparatus, wherein the control unit controls the laser output and the moving speed in the cutting end region based on a search result of the search unit.
A laser processing apparatus,
A laser oscillator;
A laser processing head for condensing laser light and irradiating the workpiece;
An assist gas supply unit for supplying an assist gas to the laser processing head;
A control unit for controlling a laser output of the laser oscillator and a relative moving speed of the laser processing head with respect to a workpiece;
A memory for storing processing conditions in the cutting end region of the closed path corresponding to the material and thickness of the work when laser cutting the work along the closed path using oxygen as an assist gas;
An input unit for inputting the processing conditions in the cutting end region to the memory,
The laser processing apparatus, wherein the control unit controls the laser output and the moving speed in the cutting end region based on the processing conditions in the cutting end region input to the memory.