JP2010052030A - Numerical control apparatus for controlling laser beam machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical control apparatus for controlling a laser beam machine which can select optimum machining conditions by predicting residual heat on the basis of distances and time periods from the portion of a workpiece machined in the past. <P>SOLUTION: The numerical control apparatus for controlling the laser beam machine includes: a heat dissipation base time memory a4; a machining history memory a3 which memorizes a machining position and the machining time for each certain moving distance predetermined during laser beam machining as the past machining position and the past machining time; a machining history acquisition means a5 which obtains, from the machining history memory a3 during laser beam machining, the past machining position nearest to a present machining position and the past machining time; a ratio computing means a6 which computes the time difference between the past machining time obtained by the machining history acquisition means a5 and the present machining time, and computes the ratio of the computed time difference to the heat dissipation base time memorized by the heat dissipation base time memory; a machining condition memory a7 which memorizes laser beam machining conditions according to the ratio; and a laser beam machining condition selecting means a8 which selects the laser beam machining conditions memorized in the machining condition memory a7 according to the ratio computed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a numerical control device that controls a laser processing machine that performs processing using laser light, such as welding, cutting, and heat treatment.

  In a processing apparatus such as a laser processing machine, the temperature of a processed portion of a workpiece increases due to laser light or the like, and this temperature increase causes a decrease in processing accuracy and causes processing defects. For this reason, cooling by natural heat dissipation of the processing part, or the worker changes the processing order intentionally so that the parts where heat is not stored are processed in order, or processing commensurate with the temperature rise of the processing part Changes to condition parameters have been made.

  The cooling by the natural heat radiation of the processing part needs to be interrupted until the processing part is cooled, which increases the processing time and decreases the processing efficiency.

  When the parameter of the machining condition is changed by the operator, the burden on the operator is large, and the operator needs knowledge such as a numerical control program to change the parameter. In addition, every time the parameter is changed, the processing operation by the laser processing machine must be temporarily interrupted, leading to a reduction in the operating rate of the laser processing apparatus, which is an obstacle to the promotion of automatic operation.

  When changing the processing order, the processing is not performed in an efficient order, and the time required for the processing becomes longer. In addition, there is a limit to the heat countermeasures by this processing order, and there is no heat escape at the end of the workpiece. Therefore, it cannot be avoided that processing defects occur.

  For example, Patent Literature 1 to Patent Literature 3 are disclosed as a technique for disclosing a technique for changing to a parameter of a machining condition corresponding to a temperature rise of a machining portion. Patent Document 1 discloses an edge processing technique that automatically changes the laser processing conditions of a block in consideration of the influence of heat generated during laser processing in a numerical control device that controls a laser processing machine. This edge processing technique is to change the laser processing conditions (movement speed, power, frequency, duty) at the start of movement of the next block according to the corner angle between blocks of the processing program. Patent Document 2 discloses a technique for measuring a surface temperature at a workpiece machining position during laser machining and correcting machining condition data when the measured value exceeds a preset reference value. Patent Document 3 discloses a technique for automatically correcting a machining condition to an optimum value according to a temperature detected by a temperature sensor that detects a temperature of a processed part of a workpiece.

JP 10-258374 A JP-A-8-39273 Japanese Patent Application Laid-Open No. 7-100674

  In a laser processing machine, if the part currently being processed is close to the processed part of the workpiece, or if the elapsed time after processing is short, sufficient heat is dissipated from the part currently being processed on the workpiece. Processing may be performed without being performed, and processing quality may be affected.

  The technique disclosed in Patent Document 1 described in the background art is based on a laser beam because a processed part other than a corner part between blocks is close when a micro-process in which a micro-block is continuous is performed on a workpiece. There is a problem that it is necessary to change the laser machining conditions for each block in consideration of the influence of heat and to create a machining program. In addition, the techniques disclosed in Patent Document 2 and Patent Document 3 require that a laser processing machine be provided with a temperature sensor that measures the temperature of a workpiece in order to set laser processing conditions, and there is a problem that the apparatus becomes complicated. there were.

  The object of the present invention is to predict the residual heat from the distance and time from the previously processed part (processed part) to the part to be processed of the workpiece, and to set the processing conditions of the laser processing machine optimally. Thus, it is an object of the present invention to provide a numerical control device that controls a laser processing machine capable of obtaining stable processing quality.

  The invention according to claim 1 of the present application is a laser processing in which processing is performed by irradiating a laser beam while relatively moving the processing object and a laser head that irradiates the laser beam to a plurality of processing points in the processing object. In a numerical control device for controlling a machine, a heat dissipation reference time storage means for storing a reference time for heat dissipation of a laser processing machine, a processing position and a processing time during laser processing at a predetermined fixed moving distance or every predetermined time The machining history storage means for storing the past machining position and its past machining time, the position currently machining during laser machining, the past machining position closest to that position, and the past machining time from the machining history storage means Calculating the difference between the machining history acquisition means to be acquired and the past machining time acquired by the machining history acquisition means and the current machining time that is currently being machined. Ratio calculating means for calculating the ratio of the difference time and the reference time for heat dissipation stored in the heat dissipation reference time storage means, processing condition storage means for storing laser processing conditions in association with the ratio, and Laser processing condition selection means for selecting a laser processing condition stored in the processing condition storage means based on the ratio calculated by the ratio calculation means, and a laser based on the laser processing condition selected by the laser processing condition selection means. A numerical control device for controlling a laser processing machine, characterized by controlling the processing machine.

  The invention according to claim 2 is characterized in that the processing condition storage means stores the laser processing condition for each predetermined ratio, and controls the laser processing machine based on the laser processing condition of the ratio corresponding to the calculated ratio. A numerical controller for controlling the laser beam machine according to claim 1.

  In the invention according to claim 3, when the calculated ratio is between the ratios stored in the processing condition storage means, the laser processing conditions are calculated by interpolation from the laser processing conditions stored in the processing condition storage means. The numerical control device for controlling a laser beam machine according to claim 2, further comprising: an interpolation unit configured to control the laser beam machine according to the calculated laser beam machining condition.

  In the invention according to claim 4, the heat dissipation reference time storage means stores a reference time for ignoring the influence of heat dissipation together with a reference time for heat dissipation, and the machining history acquisition means is stored in the machining history acquisition means. When the time of the difference between the past machining time and the current machining time currently being machined is outside the reference time for the heat dissipation or within the reference time for ignoring the influence of the heat dissipation, the processing history acquisition means The past machining position corresponding to the past machining time is excluded from the past machining positions stored in, and the current machining position during laser machining, the past machining position closest to the position, and the past machining time are determined. It is a numerical control apparatus which controls the laser processing machine as described in any one of Claims 1-3 acquired from the said process log | history memory means.

  According to the present invention, it is possible to predict the residual heat from the distance and time from the previously processed part (processed part) to the part to be processed in the past, and to set the processing conditions of the laser processing machine optimally. It is possible to provide a numerical control device for controlling a laser processing machine capable of obtaining stable processing quality.

  The principle of the present invention is that the distance from the previously processed part (processed part) to the part of the workpiece to be processed (in other words, the position currently processed during laser processing) and the elapsed time from the processing. And predicting the residual heat and controlling the processing conditions of the laser processing machine based on this prediction. In the present invention, the machining position and the machining time of the part machined in the past used for predicting the residual heat are obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining that the current processing position and processing time are stored in the processing history storage means for each predetermined moving distance or every predetermined time during laser processing. Here, the case where it memorize | stores for every fixed movement distance is demonstrated as an example. The machining position and the machining time stored in the machining history storage means are physical quantities used for predicting the residual heat from the previously machined part (machined part) with respect to the part to be machined from now on. . The machining position and its machining time stored in the machining history storage means are hereinafter referred to as a past machining position and its past machining time, respectively.

  As shown in FIG. 1, the machining position and the machining time are acquired for each predetermined moving distance during laser machining, and stored in the machining history storage means in the order of acquisition. In FIG. 1, the machining position and the machining time at the position indicated by the machining position index i (1) are acquired. Then, the machining position and the machining time at the position indicated by the machining position index i (2) obtained by moving the laser machining machine by a predetermined moving distance are acquired. Hereinafter, similarly, the machining position from the machining position index i (3) to the position of the machining position index i (11) and the machining time are sequentially acquired.

  FIG. 2 is a diagram for explaining past machining positions and past machining times stored in the machining history storage means. The past machining position and the number of past machining times stored in the machining history storage means can be set by parameters. The machining position and the machining time at the position for each fixed movement distance obtained along the machining path are sequentially stored in the machining history storage means, and the old machining position exceeding the storage area and the information of the machining time are sequentially deleted. . For example, FIG. 2 shows that past machining positions and past machining times at 12 positions are stored in the machining history storage means.

  In FIG. 1, when the laser processing proceeds and the machining position and the machining time at the next position of the machining position index i (12) are acquired, the machining position index i (1) as shown in FIG. The past machining position and the past machining time information are deleted, and the past machining position and the past machining time of the machining position index i (13) are stored in the storage column c (0). In FIG. 2 and FIG. 4, the storage area of the processing history storage means for storing the past processing position and the past processing time is twelve from c (0) to c (11). The number of storage areas is set by parameters. it can.

  In the above description, the machining position and the machining time are acquired for each fixed movement distance. However, the machining position and the machining time may be acquired for each fixed time. The machining position acquired at regular intervals and the machining time are also stored in the machining history storage means (memory of the numerical controller) as shown in FIGS.

Next, a flowchart of an algorithm for storing the machining position and the machining time in the machining history storage means for each fixed movement distance of the laser machining path shown in FIG. 5 will be described.
(Step SA1) The moving distance L of the processing position of laser processing is integrated. The movement distance calculates the movement distance to the current machining position based on the machining program. For example, the movement distance of the machining position can be obtained by calculating the distribution movement amount for each interpolation cycle or by adding the displacement amount for each interpolation cycle of the current position stored in the current position register. . When integration is performed for each interpolation cycle, L = 0 is set as the initial value of the movement distance for the first time.
(Step SA2) It is determined whether or not the movement distance calculated in Step SA1 has reached a predetermined fixed movement distance. If the fixed moving distance has not been reached, the processing in the interpolation cycle is terminated. If the fixed moving distance has been reached, the process proceeds to step SA3.
(Step SA3) The position of each axis as the machining position and the machining time at this machining position are stored in the machining history storage means as the past machining position and the past machining time, and the process proceeds to Step SA4. The position of each axis is stored in the current position register and the position data, and the time is read out from the time data stored in the current position register and stored in the machining history storage means.
(Step SA4) In order to calculate the movement distance to the next machining position, the movement distance L is reset to 0 (zero), and the process in the cycle ends.

FIG. 6 is a flowchart of an algorithm for storing the processing position and the processing time in the processing history storage means for every predetermined elapsed time of laser processing. The flowchart shown in FIG. 6 is a flowchart of an algorithm in which the steps set for each constant movement distance in the flowchart shown in FIG.
(Step SB1) The elapsed time of laser processing is counted (T = T + ΔT). The elapsed time can be counted using, for example, a timer. When integration is performed for each interpolation cycle, T = 0 is set as the initial value of the elapsed time for the first time.
(Step SB2) It is determined whether or not the elapsed time counted in step SB1 has reached a predetermined time. If the fixed time has not been reached, the processing in the interpolation cycle is terminated, and if the fixed time has been reached, the process proceeds to step SB3.
(Step SB3) The position of each axis as the machining position and the machining time at this machining position are stored in the machining history storage means as the past machining position and the past machining time, and the process proceeds to Step SB4. The position of each axis is stored in the current position register and the position data, and the time is read out from the time data stored in the current position register and stored in the machining history storage means.
(Step SB4) In order to calculate the movement distance to the next machining position, the elapsed time T is reset to 0 (zero), and the processing in the cycle ends.

  Next, the processing condition storage means used for setting the laser processing conditions will be described. FIG. 7 is a diagram for explaining storing laser processing conditions corresponding to the ratio of the reference time for heat dissipation. The “ratio to the reference time for heat dissipation” described in FIG. 7 is the ratio of the elapsed time from the time of laser processing to the workpiece (work) and the reference time for heat dissipation.

  A ratio that becomes a reference when changing to a laser processing condition corresponding to a ratio to a reference time for heat dissipation is determined, and a processing condition corresponding to the ratio is stored in the processing condition storage unit together with the ratio. The ratio that can be set can be freely set between 0% and 100%. The reference time for heat dissipation sets the time when the workpiece (work) is heated by laser processing and is predicted to be sufficiently radiated from the heated workpiece (work). The estimated time for heat dissipation, which is the expected time, differs depending on the laser processing conditions, the material of the workpiece (workpiece), and the thickness. Ask. Therefore, the reference time for heat dissipation in the embodiment of the present invention is set for each laser processing condition. The laser processing conditions include the moving speed, power, frequency, and duty of the laser head.

  In the laser processing conditions for each ratio shown in FIG. 7, when the ratio to the reference time for heat dissipation is 0%, the processing condition is 1, the processing condition is 2 when the ratio is 1, the processing condition is 3 when the ratio is 2, and the processing condition is 4 when the ratio is 3. In the ratio 4, the processing condition 5 is set. In addition, when it is 100% or more, a command read from the NC program may be stored as a machining condition (standard value). In addition, if it is 100% or more, machining may be performed in accordance with an NC program command.

  Next, referring to FIG. 1, the processing position and processing time stored in the processing history storage means are used to describe the influence of residual heat on the current processing position (hereinafter referred to as “current processing position”) during laser processing. In order to predict by the above, it will be described that the past machining position closest to the current machining position is obtained from the machining history storage means.

  In FIG. 1, a past machining position having the shortest distance from the current machining position P to the past machining position (machining position index i (1) to machining position index i (11)) is acquired. Since the past machining positions acquired as the current machining position P and the machining position index i (1) to the machining position index i (11) are identified, the shortest machining position can be easily identified. In FIG. 1, the machining position closest to the current machining position P is the machining position index i (9), and the coordinates are indicated by P9 (see FIG. 2).

  The past machining time of the past machining position P9 indicated by the machining position index i (9) is T9. If the current time at which the current machining position is being machined (hereinafter referred to as “current machining time”) is T, the difference time between the current machining time T and T9 is calculated, and the calculated difference time and heat dissipation are required. The ratio with the reference time is calculated. Using this calculated ratio, the processing conditions of the laser processing machine can be selected based on the laser processing conditions for each ratio shown in FIG.

  In FIG. 1, the past machining position closest to the current machining position P is extracted from all machining positions stored in the machining history storage means. However, as shown in FIG. 3, in the case of a past machining position close to the current machining position as shown in the machining position index i (12) as the machining position stored in the machining history storage means, immediately before the current machining position. The residual heat at the machining position is taken into consideration. Then, the laser processing conditions are changed based on the past processing position, and there is a possibility that the laser processing control may become unstable, which is inconvenient.

  Further, it is assumed that the machining position index i (1) to i (3) represents a machining position where the elapsed time from the past machining time to the current machining time exceeds the reference time for heat dissipation. Then, the influence of the residual heat on the current machining position from the past machining position can be ignored. For this reason, as shown in FIG. 3, machining positions corresponding to the reference time in which the influence of heat radiation stored in the machining history storage means is ignored and the time outside heat radiation time are excluded, and the current machining position P Get the machining position closest to.

FIG. 8 is a diagram for explaining that the laser power is changed as a laser processing condition in accordance with the ratio to the reference time for heat dissipation. In the graph shown in FIG. 8, the laser power is set when the ratio to the reference time for heat dissipation is 0%, ratio 1, ratio 2, ratio 3, ratio 4, and 100%. If this ratio is between the set ratios, the laser power setting condition is obtained by interpolating from the processing conditions of two adjacent laser powers by the interpolating means. The interpolation means calculates the laser power corresponding to the ratio by dividing the processing conditions of the two adjacent laser powers according to the ratio.
The interpolation method can be used in the same way even when the processing conditions are other than the laser power. FIG. 8 also shows the reference time during which the influence of heat dissipation described above is ignored and the time outside the reference time required for heat dissipation.

Next, a flowchart of an algorithm for selecting the laser processing conditions shown in FIG. 9 will be described.
(Step SC1) The past machining position closest to the current machining position and the past machining time are acquired. Since the current machining position and the past machining position can be acquired, the distance between the past machining position stored in the machining history storage means and the current machining position is calculated, the past machining position with the shortest distance is specified, The past machining position and the past machining time are acquired.
(Step SC2) The elapsed time from the past machining time acquired in step SC1 to the current machining time at the current machining position during laser machining is calculated.
(Step SC3) The ratio between the elapsed time calculated in step SC2 and the reference time for heat dissipation is calculated.
(Step SC4) Selection is made from the machining condition storage means based on the ratio calculated in Step SC3.
(Step SC5) The laser processing machine is controlled in accordance with the laser processing conditions selected in step SC4.

  Next, the present invention will be described using the functional block diagram shown in FIG. FIG. 10 shows numerical values for controlling a laser processing machine that performs processing by irradiating laser light while relatively moving the processing object and a laser head that irradiates laser light to a plurality of processing points in the processing object. A schematic functional block of the control device is shown.

  The numerical control unit a1 analyzes the machining program and performs interpolation processing in the same manner as a normal numerical control device, calculates the movement amount for each interpolation period to each axis, and outputs it to the axis control circuit a10. The amplifier a11 drives a servo motor connected to the amplifier a11 based on a command from the axis control circuit a10.

In the present invention, a heat dissipation reference time storage unit a4 that stores a reference time for heat dissipation of the laser processing machine, and a past processing at a predetermined moving distance or every predetermined time for a processing position and processing time during laser processing. The processing history storage unit a3 that stores the position and its processing time, and the position currently processed during laser processing, the past processing position closest to that position, and the past processing time are acquired from the processing history storage unit a3. The machining history acquisition unit a5, the difference time between the past machining time acquired by the machining history acquisition unit a5 and the current machining time currently being processed are calculated, and the calculated difference time and the heat radiation reference time storage unit a4 A ratio calculation unit a6 that calculates a ratio to the reference time for heat dissipation stored in the process, a processing condition storage unit a7 that stores a laser processing condition in association with the ratio, and a laser processing condition selection It is provided with a means a8.
Based on the ratio calculated in the ratio calculation unit a6, the laser processing condition selection unit a8 selects the laser processing condition stored in the processing condition storage unit a7, and the laser control unit based on the selected laser processing condition. The moving speed of a9 to the numerical controller a1 is controlled (for example, speed control by override) to control the laser processing machine.

FIG. 11 is a schematic block diagram for explaining an embodiment of a laser processing system for selecting laser processing conditions and executing laser processing according to the present invention.
The numerical control device 1 is configured around a processor (CPU) 10. The processor (CPU) 10 is connected to the ROM 11, FROM 12, RAM 13, timer 14, clock circuit 15, I / O unit 16, LCD / MDI 17, and axis control circuit 18 via a bus 19.

  The ROM 11 stores a system program for controlling the entire numerical controller. Further, the FROM 12, which is a non-volatile memory, stores a machining program to be retained even after the power is turned off, a program for executing the present invention, and various parameters. The heat radiation reference time storage means and the processing condition storage means correspond to the FROM 12.

  The RAM 13 stores temporary calculation data and display data, various data input by the operator via the LCD / MDI unit 17, and the like. The RAM 13 has a machining history storage unit, a current position register for storing the current position of the machining head 35, and a current time register area for storing the current time.

  The timer 14 is a means for measuring time, which can be started, reset, and turned off by a command from the processor (CPU) 10. The clock circuit 15 is a clock that holds the date and time. The RAM 13 current time register holds the current time based on the date and time information of the clock circuit 15.

  The I / O unit 16 receives a control signal from the processor (CPU) 10 and sends the control signal to the laser light oscillation unit 20. The laser beam oscillation unit 20 reflects the pulsed laser beam 21 by the reflection mirror 22 according to the received control signal and sends it to the laser processing machine 30.

  The LCD / MDI 17 is a manual input device with a liquid crystal display device, and an operator can input various programs and data interactively using the LCD / MDI 17. The axis control circuit 18 drives and controls servo motors 31, 32, and 33 provided in the laser processing machine through a servo amplifier (not shown) in accordance with a movement command from the processor (CPU) 10.

  The laser processing machine 30 includes a processing machine main body 34, a processing head 35 that irradiates the workpiece 38 with the laser beam 21, and a table 37 on which the work 38 is fixed. The laser beam 21 introduced into the processing head 35 and condensed is irradiated onto the workpiece 38 from the nozzle 36.

It is a figure explaining storing the present position and processing time for every predetermined distance or every fixed time during laser processing in processing history storage means. It is a figure explaining the processing position memorize | stored in a process history memory | storage means, and its process time. This figure explains how to exclude the processing position and the processing time within the reference time for ignoring the influence of heat dissipation outside the reference for heat dissipation when specifying the processing position closest to the current processing position during laser processing. is there. It is a conceptual diagram of the process position memorize | stored in the process history memory | storage means updated sequentially, and its process time. It is a flowchart of the algorithm which memorize | stores a process position and its process time in a process history memory | storage means for every fixed movement distance of a laser processing course. It is a flowchart of the algorithm which memorize | stores a process position and its process time in a process history memory | storage means for every fixed elapsed time of a laser process. It is a figure explaining memorizing | storing the laser processing conditions corresponding to the ratio of the reference time concerning heat dissipation. It is a figure explaining changing a laser power according to a ratio as processing conditions. It is a flowchart of the algorithm which selects laser processing conditions. It is a general | schematic functional block diagram of this invention. It is a block diagram explaining a laser processing system.

Explanation of symbols

P Current machining position (current machining position during laser machining)
1 Numerical control device 10 Processor (CPU)
11 ROM
12 FROM
13 RAM
14 Timer 15 Clock circuit 16 I / O unit 17 LCD / MDI
18 Axis Control Circuit 19 Bus 20 Laser Light Oscillator 30 Laser Processing Machine 31, 32, 33 Servo Motor 34 Laser Processing Machine Body 35 Head 36 Nozzle 37 Table 38 Workpiece

Claims (4)

In a numerical control apparatus for controlling a laser processing machine that performs processing by irradiating laser light while relatively moving the processing object and a laser head that irradiates laser light with respect to a plurality of processing points in the processing object,
A heat dissipation reference time storage means for storing a reference time for heat dissipation of the laser processing machine;
Machining history storage means for storing a machining position and its machining time during laser machining as a past machining position and its past machining time every predetermined moving distance or every predetermined time;
Processing history acquisition means for acquiring the position currently processed during laser processing, the past processing position closest to that position, and the past processing time from the processing history storage means;
The difference time between the past machining time acquired by the machining history acquisition means and the current machining time currently being processed is calculated, and the calculated difference time and the heat dissipation stored in the heat dissipation reference time storage means are applied. A ratio calculating means for calculating a ratio to the reference time;
Processing condition storage means for storing laser processing conditions in association with the ratio;
Laser processing condition selection means for selecting a laser processing condition stored in the processing condition storage means by the ratio calculated by the ratio calculation means,
A numerical control apparatus for controlling a laser processing machine, wherein the laser processing machine is controlled based on a laser processing condition selected by the laser processing condition selecting means.   2. The laser according to claim 1, wherein the processing condition storage unit stores the laser processing conditions for each predetermined ratio, and controls the laser processing machine based on the laser processing conditions of the ratio corresponding to the calculated ratio. A numerical control device that controls the processing machine.   When the calculated ratio is between the ratios stored in the processing condition storage means, the laser processing conditions are calculated by interpolation from the laser processing conditions stored in the processing condition storage means, The numerical control device for controlling a laser beam machine according to claim 2, wherein the laser beam machine is controlled according to the calculated laser beam machining condition. The heat dissipation reference time storage means stores a reference time for ignoring the influence of heat dissipation together with a reference time for heat dissipation,
The processing history acquisition means includes
If the time of the difference between the past machining time stored in the machining history acquisition means and the current machining time currently being processed is outside the reference time for the heat dissipation or within a reference time for ignoring the influence of the heat dissipation In this case, the past machining position corresponding to the past machining time is excluded from the past machining positions stored in the machining history acquisition unit, and the position currently being machined during laser machining and the position closest to the position. The numerical control apparatus for controlling a laser beam machine according to any one of claims 1 to 3, wherein a past machining position and a past machining time are acquired from the machining history storage unit.

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