LASER CONTROLLER

Abstract

A laser controller is configured to output a laser beam in response to the input of command power. The laser controller receives the input of the command power and the input of an acceleration of the relative movement of a laser machining head and a workpiece, calculates output power based on the command power and a coefficient corresponding to the acceleration, and outputs the laser beam according to the calculated output power.

Claims

1. A laser controller configured to output a laser beam in response to the input of command power, the laser controller comprising: an input unit configured to accept the input of the command power and the input of an acceleration of the relative movement of a laser machining head and a workpiece; a laser control unit configured to calculate output power based on the command power and a coefficient corresponding to the acceleration; and a D/A conversion unit configured to output the laser beam according to the output power.

2. A laser controller configured to output a laser beam in response to the input of command power, the laser controller comprising: an input unit configured to accept the input of the command power and the input of a speed of the relative movement of a laser machining head and a workpiece; a laser control unit configured to calculate output power based on the command power and a coefficient corresponding to a change of the speed; and a D/A conversion unit configured to output the laser beam according to the output power.

3. The laser controller according to claim 1, wherein the laser control unit performs such control as to gradually increase the output power while the relative movement of the laser machining head and the workpiece is being accelerated.

4. The laser controller according to claim 1, wherein the laser control unit performs such control as to gradually decrease the output power while the relative movement of the laser machining head and the workpiece is being decelerated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a diagram showing a configuration example of a numerical controller for controlling conventional laser machining;

[0018] FIG. 2 is a diagram showing a configuration example of a robot used to perform the conventional laser machining;

[0019] FIG. 3 is a diagram showing the configuration of a laser controller according to Embodiment 1 of the present invention;

[0020] FIG. 4 is a diagram showing the operation of the laser controller according to Embodiment 1 of the present invention;

[0021] FIGS. 5A and 5B are diagrams showing the operation of the laser controller according to Embodiment 1 of the present invention; and

[0022] FIG. 6 is a diagram showing the configuration of a laser controller according to Embodiment 2 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A laser controller according to Embodiment 1 of the present invention will first be described with reference to FIGS. 3 to 5B.

[0024] The configuration of a laser controller 100 according to Embodiment 1 of the present invention will be described with reference to the block diagram of FIG. 3. The laser controller 100 comprises an input unit 110, laser control unit 120, and D/A conversion unit 130.

[0025] The input unit 110 accepts the input of acceleration information in addition to commands such as a power command, frequency command, and duty command. Typically, a robot or numerical controller (CNC) outputs the power, frequency, duty and other commands. An acceleration sensor mounted on a table that carries a laser machining head or workpiece thereon outputs an acceleration. Preferably, these pieces of information should be digital information and the input unit 110 should be provided with a digital input interface such as Ethernet (registered trademark).

[0026] Alternatively, acceleration information generated by an interpolation processing unit of the CNC in place of the acceleration sensor may be input to the input unit 110. The interpolation processing unit, which executes interpolation processing based on an acceleration command, can generate and output the acceleration during the execution.

[0027] The laser control unit 120 monitors the acceleration which is input to the input unit 110. At the same time, it calculates laser output power by multiplying the input command power by a coefficient corresponding to the input acceleration.

[0028] The D/A conversion unit 130 outputs a laser beam based on the output power calculated by the laser control unit 120 and the command frequency and command duty input to the input unit 110.

[0029] The operation of the laser controller 100 according to Embodiment 1 will now be described with reference to the flowcharts of FIGS. 5A and 5B and the chart of FIG. 4.

[0030] The laser controller 100 performs continuous power control by repeatedly carrying out the processing shown in FIGS. 5A and 5B at regular time intervals. In the description to follow, control performed by the laser control unit 120 as the relative movement of the laser machining head and the workpiece is accelerated immediately after the input of the command power will be referred to as power control of Threshold 1; control performed by the laser control unit 120 when the relative movement of the laser machining head and the workpiece is decelerated after becoming uniform as power control of Threshold 2, and control performed by the laser control unit 120 after the relative movement is changed from deceleration to acceleration as power control of Threshold 3 (FIG. 4). [0031] Step S101: The input unit 110 accepts the input of the command power, command frequency, and command duty from the robot or CNC. [0032] Step S102: If the laser control unit 120 is already performing the power control, the program proceeds to Step S107. If not, the program proceeds to Step S103. [0033] Step S103: The laser control unit 120 determines whether or not the command power that is input to the input unit 110 is changed from 0 to a positive value (that is, any command power is input) and the acceleration has a positive value (that is, the speed of the relative movement of the laser machining head and the workpiece is being increased). Whether or not the command power is changed from 0 to the positive value can be determined by comparing the command power read in Step S101 and the command power for the immediately preceding cycle. If the result of the determination is true, the program proceeds to Step S104. If not, the program proceeds to Step S105. [0034] Step S104: The laser control unit 120 performs the power control of Threshold 1. The laser control unit 120 calculates the output power according to equation (1) as follows:

M=M.sub.ck.sub.1.(1)

[0035] Here M is the output power, M.sub.c is the command power, and k.sub.1 is a predefined magnification. Specifically, the laser control unit 120 performs control such that the output power is increased at the rate k.sub.1 per unit time before the speed of the relative movement of the laser machining head and the workpiece becomes uniform and that the command power M.sub.c of 100% is output when the speed of the relative movement of the laser machining head and the workpiece becomes uniform. [0036] Step S105: The laser control unit 120 determines whether or not the command power input to the input unit 110 has a positive value other than 0 and is not changed and that the acceleration has a negative value (that is, the relative movement of the laser machining head and the workpiece is being decelerated). Whether the command power is not changed can be determined by comparing the command power read in Step S101 and the command power for the immediately preceding cycle. If the result of the determination is true, the program proceeds to Step S106. If not, the program proceeds to Step S112. [0037] Step S106: The laser control unit 120 performs the power control of Threshold 2. The laser control unit 120 calculates the output power according to equation (2) as follows:

M=M.sub.c(1k.sub.2).(2)

[0038] Here M is the output power, M.sub.c is the command power, and k.sub.2 is a predefined magnification. Specifically, the laser control unit 120 performs control such that the output power is reduced from the command power M.sub.c of 100% at the rate k.sub.e per unit time when the relative movement of the laser machining head and the workpiece is changed from uniform motion to deceleration. [0039] Step S107: The laser control unit 120 determines whether or not the acceleration that is input to the input unit 110 is 0 (that is, the relative movement of the laser machining head and the workpiece is uniform). If the result of the determination is true, the program proceeds to Step S108. If not, the program proceeds to Step S109. [0040] Step S108: The laser control unit 120 ends the power control. [0041] Step S109: The laser control unit 120 determines whether or not the acceleration is changed from the negative value to a positive value (that is, the relative movement of the laser machining head and the workpiece is changed from deceleration to acceleration). Whether or not the command power is changed from the negative value to the positive value can be determined by comparing the command power read in Step S101 and the command power for the immediately preceding cycle. If the result of the determination is true, the program proceeds to Step S110. If not, the program proceeds to Step S111. [0042] Step S110: The laser control unit 120 performs the power control of Threshold 3. The laser control unit 120 calculates the output power according to equation (3) as follows:

M=M.sub.c(1k.sub.2+k.sub.3).(3)

[0043] Here M is the output power, M.sub.c is the command power, and k.sub.e and k.sub.3 are predefined magnifications. Specifically, the laser control unit 120 performs control such that the output power is increased from the then command power M=M.sub.c(1k.sub.2) at the rate k.sub.3 per unit time when the relative movement of the laser machining head and the workpiece is changed from deceleration to acceleration. [0044] Step S111: The laser control unit 120 continues the ongoing power control. [0045] Steps S112 to S115: The laser control unit 120 calculates the on/off time of the laser beam based on the command frequency and the command duty input to the input unit 110 in Step S101. The laser control unit 120 outputs power, beam-on time, and beam-off time to the D/A conversion unit 130. The D/A conversion unit 130 outputs the laser beam according to the input power, beam-on time, and beam-off time.

[0046] According to the present embodiment, the laser control unit 120 of the laser controller 100 calculates appropriate output power in accordance with the acceleration of the relative movement of the laser machining head and the workpiece, thereby controlling the output of the laser beam. More specifically, the laser control unit performs control such that the output power is gradually increased while the relative movement of the laser machining head and the workpiece is being accelerated. On the other hand, the laser control unit performs control such that the output power is gradually decreased while the relative movement of the laser machining head and the workpiece is being decelerated. Therefore, it is unnecessary to create a power command in consideration of the acceleration and deceleration of the relative movement of the laser machining head and the workpiece on the CNC side. By combining the laser controller 100 with a conventional laser machining robot or the like, the output power can be controlled in consideration of the acceleration and deceleration of the relative movement of the laser machining head and the workpiece.

[0047] A laser controller according to Embodiment 2 of the present invention will now be described with reference to FIG. 6 and FIGS. 5A and 5B.

[0048] A laser controller 100 according to Embodiment 2 is characterized in that speed information is used in place of the acceleration information used in Embodiment 1. Differences of the configuration and operation of Embodiment 2 from those of Embodiment 1 will be mainly described in the following, and a description of points common to these embodiments will be omitted below.

[0049] The configuration of the laser controller 100 according to Embodiment 2 of the present invention will be described with reference to the block diagram of FIG. 6.

[0050] An input unit 110 accepts the input of speed information in addition to commands such as a power command, frequency command, and duty command. Typically, a speed sensor mounted on a table that carries a laser machining head or workpiece thereon outputs a speed.

[0051] Alternatively, speed information generated by the interpolation processing unit of the CNC in place of the speed sensor may be input to the input unit 110. The interpolation processing unit, which executes interpolation processing based on a speed command, can generate and output the speed during the execution.

[0052] The laser control unit 120 monitors the speed input to the input unit 110. At the same time, it calculates laser output power by multiplying the input command power by a coefficient corresponding to the change of the speed.

[0053] The operation of the laser controller 100 according to Embodiment 2 will now be described with reference to the flowcharts of FIGS. 5A and 5B.

[0054] According to Embodiment 1 described above, the laser control unit 120 uses the acceleration information, in Steps S103, S105, S107 and S109, in order to determine whether the relative movement of the laser machining head and the workpiece is being accelerated, in uniform motion, or being decelerated. According to Embodiment 2, in contrast, the laser control unit 120 uses the speed information to determine whether the relative movement of the laser machining head and the workpiece is being accelerated, in uniform motion, or being decelerated.

[0055] For example, the laser control unit 120 can determine whether the relative movement of the laser machining head and the workpiece is being accelerated, in uniform motion, or being decelerated by comparing the speed read in Step S101 and the speed read in the immediately preceding cycle.

[0056] Alternatively, the laser control unit 120 may be configured to read a target speed in addition to the current relative movement speed of the laser machining head and the workpiece in Step S101. In this case, if the current speed is equal to the target speed (or within a fixed error range), the relative movement of the laser machining head and the workpiece can be determined to be in uniform motion. If the current speed is different from the target speed, in contrast, the relative movement of the laser machining head and the workpiece can be determined to be being accelerated or decelerated.

[0057] Also in the present embodiment, the laser control unit 120 of the laser controller 100 can calculate appropriate output power in accordance with the acceleration of the laser machining head, thereby controlling the output of the laser beam. In Embodiment 2, compared with Embodiment 1, extra processing is needed to determine the acceleration, deceleration, and uniform motion. Moreover, if the target speed is used, the input unit 110 is expected to secure variables for accepting the input of the two data, the current and target speeds.

[0058] The present invention is not limited to the above-described embodiment and may be suitably changed without departing from the spirit of the invention. Any of the constituent elements of the embodiments may be modified or omitted without departing from the scope of the present invention.