WO1997019782A1

WO1997019782A1 - Laser machining apparatus

Info

Publication number: WO1997019782A1
Application number: PCT/JP1996/003404
Authority: WO
Inventors: Yoshinori Nakata; Kazuhiro Suzuki; Motohiko Sato; Hitoshi Matsuura
Original assignee: Fanuc Ltd
Priority date: 1995-11-27
Filing date: 1996-11-20
Publication date: 1997-06-05
Also published as: JPH09150282A

Abstract

An interpolater (3) outputs an interpolation pulse for each axis in response to a movement command. The speed F of a machining head (35) moving along a machining path is calculated from the interpolation pulse (speed) for each axis and is sent to an output condition determination device (4). Based on the speed F, the output condition determination device (4) calculates the corresponding output power M(F), pulse frequency N(F) and pulse duty Q(F) and outputs them. As a result, the beam from a laser oscillator (20) is controlled by the output conditions of M(F), N(F) and Q(F).

Description

Specification

Laser processing equipment

Technical field

The present invention relates to a type of laser processing apparatus that controls a beam output condition at the time of laser processing according to a moving speed of a processing head with respect to a workpiece.

Background technology

When performing laser processing, it may be necessary to decelerate at a bent portion or a corner to secure dimensional accuracy, depending on the shape of the processing path. Then, the laser beam is irradiated for a long time in the decelerated area (low-speed section). At this time, if the output of the laser beam is maintained at the same power, the width of the processing is increased only in the low-speed part. In particular, excessive heat input occurs at the top of the corners, resulting in poor machining quality, such as the inability to sharpen the corners.

In the past, by controlling the output power of the laser beam according to the speed change, the output power of the laser beam was reduced at the part where the processing speed was low. As a result, it is possible to suppress the deterioration of the processing quality in the low-speed part.

The laser beam output conditions for laser processing include pulse duty and pulse frequency in addition to output power. As in the case of controlling output power, beam output conditions such as pulse duty correspond to speed changes It was also used to change it.

In the past, however, only one of the beam power conditions could be changed in response to the processing speed. Therefore, good machining results can only be obtained with specific machining. For example, if only the pulse duty is changed, good results can only be obtained with wood processing.

In addition, when only the output power of the beam is reduced in accordance with the reduction in the processing speed in the cutting processing, the work may not be cut due to the influence of the dross in the processed part. As a result, the output power cannot be reduced so much, and eventually the deterioration of the processing quality in the low-speed section cannot be prevented.

In addition, in the case of the control method in which only the pulse duty is changed, when the vehicle is decelerated before the corner, etc., the stripe pattern on the processing surface formed by the laser pulse becomes inconsistent, and the processing quality is reduced. Getting worse.

As described above, conventionally, only one of the beam output conditions could be controlled in accordance with the processing speed, so that deterioration of the processing quality could not be prevented.

Disclosure of the invention

It is an object of the present invention to provide a laser processing apparatus capable of controlling a plurality of beam output conditions in accordance with a change in a moving speed.

In order to achieve the above object, a laser processing apparatus according to the present invention is configured such that a movement command value is input to a laser beam on a processing path of a processing head. A moving speed calculating means for calculating and outputting the moving speed of the beam, and inputting the moving speed output from the moving speed calculating means, and values of two or more types of beam output conditions corresponding to the moving speed. And a beam output control means for controlling the laser oscillator based on the value of the beam output condition output by the output condition determining means.

Preferably, for at least one type of beam output condition, the output condition determining means determines the beam output condition based on a relational expression between the moving speed and the value of the output condition. Is provided.

Preferably, the output condition determining means has a data table in which the correspondence between the moving speed and at least one type of beam output condition is defined, and the moving speed is input. Then, referring to the data table and outputting the value of the output condition corresponding to the moving speed.

Since the present invention has the above-described configuration, it is possible to control a plurality of elements of the beam output condition in any combination in response to a change in the feed rate during laser processing. In machining under various conditions, the machining part is uniform and good and optimal machining results can be obtained.

Brief explanation of drawings

FIG. 1 is a block diagram showing each element constituting the laser processing apparatus according to the present invention.

FIG. 2 is a schematic diagram showing one embodiment of a laser processing apparatus according to the present invention. Is a schematic diagram,

FIG. 3 is a diagram showing an example of a processing path when processing is performed by a laser processing apparatus.

Fig. 4 is a diagram showing the moving speed of the machining head when it moves on the machining path shown in Fig. 3,

Figure 5 shows the relationship between the moving speed of the processing head and the pulse frequency of the laser beam.

Fig. 6 shows the output power of the laser beam on the machining path shown in Fig. 3.

Fig. 7 is a diagram showing the pulse frequency of the laser beam on the machining path shown in Fig. 3.

FIG. 8 is a diagram showing an example of a data table in which the relationship between the moving speed of the processing head and the output power of the laser beam is determined.

FIG. 9 is a diagram showing the contents of the data table of FIG. 8 in a graph, and

Fig. 10 shows the relationship between the position on the machining path and the moving speed in Fig. 4 replaced by the relationship between the position on the machining path and the output power of the laser beam using the data table shown in Fig. 8. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION First, the function of the laser processing apparatus according to the present invention, which is constituted by the elements having the functions, will be described with reference to the block diagram of FIG. I do.

Preprocessing calculation means 2 decodes processing program 1 and moves Output command. The interpolation means 3 performs an interpolation process on the movement command and outputs an interpolation pulse for each axis. Further, the interpolation means 3 calculates the relative moving speed F of the machining head 35 with respect to the workpiece from the interpolation pulse for each axis. The servo amplifier 18 controls the rotation of the servomotor 32 of the laser beam machine 30 according to the interpolation pulse. There are as many servo amplifiers 18 and servo motors 32 as the number of axes. In the output condition determining means 4, a plurality of beam output condition values for the moving speed F are defined in advance. In this example, the output power, the pulse frequency, and the value of the pulse duty are defined by the output power definition unit 4a, the pulse frequency definition unit 4b, and the pulse duty definition unit 4c, respectively. The output condition determining means 4 determines the values of the output power M, the pulse duty Q, and the pulse frequency N according to the definition of each beam output condition based on the moving speed F calculated by the interpolation means 3. To define each beam output condition, use a beam output condition calculation formula that uses the moving speed as a variable, or use a data table that registers the correspondence between the moving speed and the set value of each beam output condition. And can be. In the former case, the output power is determined to be M (F), the pulse duty is determined to be Q (F), and the pulse frequency is determined to be N (F). In the latter case, the travel speed F i-1 to F i (i = l, 2, 3, ...)ヮ一 is M i, no ,. The pulse duty is determined to be Q i, and the pulse frequency is determined to be N i. The laser output control means 5 controls the beam output of the laser oscillator 20 according to the beam output conditions calculated by the output condition determining means 4. The laser beam output from the laser oscillator 20 is applied to the work via the processing head 35.

Thus, a plurality of beam output conditions can be simultaneously controlled according to the moving speed during laser processing. Therefore, it is possible to obtain better processing quality in various situations than when one type of beam output condition is controlled.

Next, an embodiment of the laser processing apparatus according to the present invention will be described with reference to the schematic diagram of FIG.

In FIG. 2, the laser processing device includes a numerical controller (CNC) 10, a laser oscillator 20, and a laser processing machine 30.

The CNC 10 is connected to the processor (CPU) 11 via the NOS 50 via the R〇M 12, the nonvolatile memory 13, the RAM 14, and the I / O unit 15. A manual input device with display screen (CRT MDI) 16 and servo amplifiers 17, 18, and 19 are connected to each other.

EPROM or EEPROM is used for R0M12, and the system program is stored. The non-volatile memory 13 uses the CM0S that has been knocked down and stores machining programs and various parameters to be retained even after the power is turned off. Therefore, the processor 11 reads the machining program stored in the non-volatile memory 13 based on the system program stored in the ROM 12. To control the operation of the entire system.

The IZ〇 unit 15 converts the output control signal from the processor 11 and sends it to the laser oscillator 20. The laser oscillator 20 emits a continuous or pulsed laser beam 21 in accordance with the output control signal. The laser beam 21 is reflected by the bending mirror 22 and sent to the laser beam machine 30.

The CRT / MDI16 is used to interactively input various program data to the CNC10.

The laser processing machine 30 includes a processing machine body 34, a processing head 35 for irradiating the work 38 with the laser beam 21, and a table 37 to which the workpiece 38 is fixed. The laser beam 21 introduced into the processing head 35 and condensed is applied to the work 38 from the nozzle 36.

The servo amplifiers 17, 18, and 19 are connected to the X-axis support motor 31 of the laser beam machine 30, the Y-axis servo motor 32, and the Z-axis servo motor 33, and are connected to the processor. The axis control signal from the satellite 11 is transmitted to these satellites 31, 32, 33.

The laser machine body 34 is provided with an X-axis servomotor 31 for controlling the movement of the table 37 in the X-axis direction and a Y-axis servomotor 32 for controlling the movement of the table 37 in the Y-axis direction. . In addition, a Z-axis servo motor 33 is provided for controlling the movement of the machining head 35 in the Z-axis direction. These servo motors 33, 32 and 33 are provided. The CNC 1 It is connected to the servo amplifiers 17, 18 and 19 on the 0 side, respectively, and its rotation is controlled according to the axis control signal from the processor 11. The table 37 and the processing head 35 move in accordance with the rotation of the sub-bodies 31, 32, and 33. The laser beam 21 emitted from the nozzle 36 draws a trajectory on the work 38 in accordance with the movement of the table 37, and cuts the work 38 into a predetermined shape or welds along a predetermined path. Processing such as doing.

A case where a plurality of beam output conditions are controlled in accordance with the moving speed by the laser processing apparatus as described above will be specifically described below.

Fig. 3 shows an example of the processing path when processing with a laser processing device. In the machining path 40, the spots 41 to 43 of the laser beam moving on the path 40 have their center positions moved in the order of point A-point B-point C. In this case, the movement from point A to point B is linear. It makes a right angle turn at point B and moves straight from point B to point C. Therefore, it is necessary to reduce the speed at point B as compared with the movement before and after that point.

Therefore, the speed of the irradiation spot (processing head 35) moving on the processing path 40 in FIG. 3 is represented in a graph as shown in FIG. In FIG. 4, the horizontal axis indicates the center position of the spot on the machining path 40, and the vertical axis indicates the moving speed when passing through that position. Shortly after passing point A, deceleration starts. At point B, the speed is lowest. Acceleration starts after passing point B, before point C But return to and speed. After that, pass point C while maintaining the speed.

When the processing head 35 moves in the mode shown in Fig. 4, the output power M, pulse frequency N, and pulse duty Q corresponding to the speed F are commanded.

For example,

(a) The output power M (F) for the speed F is determined by the following equation.

M (F) = a F ² (1) where α is a proportionality constant.

(b) The pulse frequency N (F) for the speed F is determined by the following formula.

N (F) = / 3 F + N 0 (2) where N O is the set pulse frequency when F = 0. The proportional constant / 3 is calculated by the following formula.

β = (Nc-Ν0) ZFc, where Nc is the optimum pulse frequency when the speed F is Fc. When the above equation (2) is represented by a graph with the horizontal axis representing the speed F and the vertical axis representing the pulse frequency N (F), the result is as shown in FIG.

(c) The pulse duty Q (F) for the speed F is determined by the following equation.

Q (F) = r F + Q 0… · (3) Here, Q 0 is the set pulse duty when F = 0. The proportionality constant r is calculated by the following equation.

r = (Qc-Q0) / Fc, where Qc is the speed F This is the optimum pulse duty for c. When the above equation (3) is represented by a graph of the speed F on the horizontal axis and the pulse duty Q (F) on the vertical axis (not actually shown), the shape is similar to FIG.

As described above, the calculation expressions of the above (1), (2), and (3) are set in the output condition calculating means 4 (shown in FIG. 1).

Therefore, when laser machining is performed while moving the machining path 40 shown in FIG. 3 at the speed F shown in FIG. 4, beam output control (output power M (F), pulse frequency N (F), The determination of the pulse duty Q (F) is made according to equations (1), (2) and (3). That is, the value of each beam output condition changes according to a change in the moving speed of the processing head 35.

FIG. 6 shows the relationship between the position on the machining path and the moving speed F in FIG. 4 replaced with the relationship between the position on the machining path and the output power using the above equation (1). In FIG. 6, the horizontal axis is the position on the movement route, and the vertical axis is the output power Q. As the deceleration starts, the output power is reduced at the same time. When the position reaches point B, the output power becomes minimum at that position. After point B, the output power gradually increases. When the moving speed F returns to the original constant speed, the output power returns to the original constant output.

FIG. 7 shows the relationship between the position on the machining path and the moving speed F in FIG. 4 replaced with the relationship between the position on the machining path and the pulse frequency using the above equation (2). In Figure 7, The horizontal axis is the position on the movement path, and the vertical axis is the pulse frequency N. As the deceleration starts, the pulse frequency decreases at the same time. When the position reaches point B, the pulse frequency becomes minimum and then increases. When the moving speed returns to the original speed, the pulse frequency returns to the original value. The pulse duty changes similarly to the pulse frequency.

In this way, by setting the calculation formula in advance, it is possible to control by arbitrarily combining all the elements of the beam output condition in response to the fluctuation of the machining feed speed. Therefore, even if the processing conditions change due to the fluctuation of the processing speed, it is possible to always perform the processing under the beam output conditions suitable for the processing conditions.

In the above example, the force for deriving the value of each condition using the calculation formula. A data table can be prepared in advance, and the value of each condition can be obtained from the data table.

FIG. 8 is a diagram showing an example of a data table. The data table has two items: "speed" and "element data". In “speed”, threshold values (F 0, F 1, F 2,..., F 5) of the speed at which the output condition should be changed are set. The “element data” includes the output power (M 0, M l, M 2,...) Until the corresponding “speed” threshold is reached.

M 5) is set. This data table is provided individually for each element of the beam output condition.

FIG. 9 is a diagram showing the relationship between the speed F and the output power M when a data table as shown in FIG. 8 is used. speed Output power M 0 when F = F 0, output power M l when the speed is F 0 <F ≤ F 1, output power M 2 when the speed is F l <F ≤ F 2, Output power M 3 when the speed is F 2 <F ≤ F 3, output power M 4 when the speed is F 3 <F ≤ F 4, and output power M 4 when the speed is F 4 <F ≤ F 5 The output power is M5.

FIG. 10 shows the relationship between the position and the output power when the beam output condition control for the movement shown in FIG. 3 is performed using such a data table. That is, the relationship between the position and the output power M in FIG. 4 is replaced by the relationship between the position and the output power M based on the relationship between the speed F and the output power M in FIG. It is. In FIG. 10, the horizontal axis is the position of the processing head, and the vertical axis is the output power M. As shown in FIG. 10, the output power gradually decreases and becomes the lowest at the point B. And, after passing point B, it gradually becomes stronger.

By setting such a data table for each beam output condition, each value changes according to the moving speed. By using the data table, the beam output condition can be obtained by simple comparison of data, so that the load on the processor of the numerical controller is reduced.

Claims

The scope of the claims

A moving speed calculating means for inputting a moving command value, calculating and outputting a moving speed of the machining head on the machining path,

An output condition determining means for inputting the moving speed output from the moving speed calculating means, obtaining and outputting two or more types of beam output condition values corresponding to the moving speed,

Beam output control means for controlling the laser oscillator based on the value of the beam output condition output by the output condition determining means,

Laser processing device equipped with.

For at least one type of beam output condition, the output condition determining means uses the relational expression between the moving speed and the value of the output condition to calculate the beam output condition from the input moving speed. The laser processing apparatus according to claim 1, further comprising means for calculating a value.

The output condition determining means has a data table that defines the correspondence between the moving speed and at least one type of beam output condition. When the moving speed is input, the data table is referred to. The laser processing apparatus according to claim 1, wherein the value of the output condition corresponding to the moving speed is output.

The types of beam output conditions determined by the output condition determining means in accordance with the moving speed are at least any two of output power, pulse frequency, and pulse duty. The laser processing apparatus according to claim 1, wherein