JPH05309484A - Control method for cutting machine - Google Patents

Abstract

PURPOSE:To prevent excessive heat input and defective cutting by calculating the temperature of each division at a work and determining a target output value of a beam for cutting based on the temperature at the division where a cutting point is located. CONSTITUTION:In the cutting machine 1, the work W is divided into many divisions and in a temperature calculation part 13, various data inputted from a memory 10 for setting a constant, a temperature sensor 12, a memory 14 for storing the temperature, etc., are used to calculate the temperature of each division for every specified time at the time of cutting work. Further, in an output value determination part 15, an output value of the beam V for cutting is determined based on the temperature obtained at the temperature calculation part 13 and a beam generator 2 is controlled according to this output value, by which the excessive heat input to the work W is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of a cutting apparatus for cutting a plate-shaped work by a cutting beam such as a laser beam or a plasma beam.

[0002]

2. Description of the Related Art A conventional cutting apparatus A shown in FIG. 5 is equipped with a beam generator B and an XY table C, and a beam D for cutting laser, plasma or the like from the beam generator B is A plate-shaped work W placed on the XY table C
Irradiating the workpiece W and moving the workpiece W relative to the cutting beam D by the X-axis drive motor Cx and the Y-axis drive motor Cy of the XY table C, so that the workpiece W is set at a predetermined position, that is, preset. Cutting is performed on the cut locus. Further, in the conventional cutting processing apparatus A, the relative moving speed of the cutting beam D with respect to the work W is detected, and the output of the cutting beam D is controlled based on this relative moving speed, or the work W When the edge part is detected, the beam D
Is controlled so as to change the output of the work W, and the work W is appropriately cut.

[0003]

By the way, when cutting the work W with a complicated shape as shown in the cutting locus E shown in FIG. 6, a small cutting angle such as the Ea portion in the cutting locus E has a small cutting angle. In the portion that is folded back at, the heat input to the work W is locally excessive because the cutting beam is continuously irradiated in a narrow area on the work W, and as a result, the cutting width is expanded and self-burning is performed. There is a risk of causing cutting failure such as. For such a situation, output control of the cutting beam D based on the relative movement speed of the work W and the cutting beam D described above, or output of the cutting beam D when the edge portion of the work W is detected. Can not be dealt with sufficiently by means such as changing. Therefore, in order to eliminate the above-mentioned inconvenience, the beam generator B is arranged to reduce the output of the cutting beam D in a portion where the heat input to the work W in the cutting trajectory is expected to be excessive.
A coping method for controlling the power supply has been proposed. However, in the above-mentioned coping method, it is necessary to create a complicated control program, and since the control program is a series of programs from the work start time, the cutting work is stopped midway and the execution of the control program is interrupted. In this case, there is a disadvantage that it becomes extremely difficult to restart the control program. In view of the above situation, the present invention provides a control method of a cutting apparatus capable of performing a cutting operation of a complicated shape on a work without causing a cutting failure due to excessive heat input. With the goal.

[0004]

Therefore, in the control method of the cutting apparatus according to the present invention, the work is divided into a large number of sections adjacent to each other, and the material of the work, the thickness of the work, and the surface state of the work. , The output value of the cutting beam, the shape of the cutting beam, the cutting trajectory, the ambient temperature, and the cooling condition of the work, the temperature in each of the above sections is calculated for each predetermined time, and the section where the cutting point is located is calculated. The above object is achieved by controlling the output value of the cutting beam based on the temperature.

[0005]

According to the above construction, the temperature of each section of the work is calculated, and based on the temperature of the section where the cutting point is located, an appropriate cutting beam that does not give excessive heat input to the work W is obtained. Since the target output value of is determined,
An optimum cutting beam output is set even for a cutting trajectory having a complicated shape, and the cutting beam output is optimally controlled even when the machining is restarted after being interrupted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing an embodiment. FIG. 1 shows an example of a cutting processing apparatus whose operation is controlled based on the control method according to the present invention.

The cutting apparatus 1 is an apparatus configured to perform a cutting process on a plate-shaped work by using a laser beam as a cutting beam, and includes a beam generator 2 for generating a laser beam. , An XY table 3 for moving the workpiece W relative to the cutting beam V.

The cutting machine 1 has a numerical control program memory 4, a numerical control unit 5, and a servo control unit 6, and a numerical control unit based on the program stored in the numerical control program memory 4. According to the command from 5, the control such as the irradiation start and the irradiation stop of the cutting beam V in the beam generator 2 is executed.

On the other hand, the XY table 3 on which the work W is placed
Is cut on the work W by the operation control of the X-axis drive motor 3x and the Y-axis drive motor 3y according to commands from the servo control unit 6 based on the numerical control program memory 4 and the numerical control unit 5, respectively. The work W is moved so that the working beam V moves along a preset cutting trajectory.
Relative to the cutting beam V.

That is, in the cutting processing apparatus 1, while the work W is irradiated with the cutting beam V from the beam generator 2, the XY table 3 moves the work W relative to the cutting beam V. Thus, the workpiece W is cut along the cutting locus, and the configuration up to this point is basically the same as that of the above-described conventional cutting apparatus (see FIG. 5A).

As shown in FIG. 1, the cutting device 1
In addition to the above-mentioned components such as the beam generator 2 and the XY table 3, a constant setting memory 10, a temperature sensor 11 for detecting an ambient temperature, a start-up timer 12, a temperature calculation unit 13, and a temperature. The memory 14 for storage and the output value determination unit 15 are provided.

In the cutting device 1, for example, Xmm * Y
The workpiece W having a mm plate shape is divided into a large number of N * M sections, and the temperature calculation unit 13 inputs the workpieces from the constant setting memory 10, the temperature sensor 11, the temperature storage memory 14, and the like. The temperature of each section for each predetermined time (for example, TBms) at the time of cutting work is calculated using various data to be cut, and the output value determination unit 15 uses the temperature calculated by the temperature calculation unit 13 for cutting. By determining the output value of the beam V and controlling the beam generator 2 according to this output value, excessive heat input to the work W is prevented.

In the constant setting memory 10, the work W
The material, the thickness of the work W, the surface state of the work W, the shape of the cutting beam V, and the cooling conditions for the work W are set and stored. The constant setting memory 10 stores the above-mentioned set values as constants that are appropriately converted in order to facilitate calculation of the temperature, which will be described later in detail.

In the temperature calculation unit 13, the constant setting memory 1
The above constants stored in 0 and the temperature sensor 1
2, the ambient temperature detected by 2, the cutting locus from the numerical control unit 5 described above, the output value of the cutting beam V based on the previous calculation result (temperature) from the output value determination unit 15, and the temperature storage memory. With the previous calculation result (contact status and temperature in each section) stored in 14 as input,
The temperature in each section of the work W is calculated every predetermined time. Further, in the temperature calculation unit 13, the change of the contact situation in each section along with the progress of the cutting process of the work W by the cutting beam V is judged, and the variable representing the contact situation is updated.

The temperature storage memory 14 stores the temperature of each section calculated by the temperature calculation unit 13 and the contact status with other sections in each section. Further, the output value determination unit 15 determines the target output value of the cutting beam V based on the temperature of the processed portion calculated by the temperature calculation unit 13 described above.

Here, in order to calculate the temperature in each section of the work W in the temperature calculation unit 13, the cutting beam V to each section in the work W will be described in detail later.
It is necessary to obtain the amount of heat input from, the amount of conduction heat between each section of the work W, and the amount of heat dissipation of each section of the work W.

The amount of heat input (QH) from the cutting beam V to each section of the work W is proportional to the output value (CW) of the cutting beam V, and at the cutting point (the point where the cutting beam hits). Is in proportion to the number of times it enters into one section, in other words, it is inversely proportional to the cutting speed,
It changes depending on the plate thickness and the material.

The plate thickness of the work W is related to the contact area between the part melted by the cutting beam and the work W. The thicker the heat input amount, the more the material of the work W is melted by the cutting beam. It influences the beam energy absorption rate of the part that is being heated and the amount of heat of reaction with the assist gas.

The plate thickness and material of the work W are fixed, and are represented by predetermined coefficients (KS and KM) obtained from experiments, experience, and calculations. The cutting beam V in the section not at the cutting point, that is, the section in which the cutting trajectory does not pass
The amount of heat input from is naturally 0.

That is, the heat input amount (QH) is calculated by the following equation. QH (n, m) = KS * KM * CW n = k, m =
When j: QH (n, m) = 0 otherwise: n = 1 to N, m = 1 to M The subscript (n, m) distinguishes each section, and the subscript (k,
J) indicates that the section has a cutting point (cutting locus).

On the other hand, the amount of conductive heat (QF) between the respective sections of the work W changes depending on the plate thickness of the work W and the material (heat conductivity) of the work W, and is proportional to the temperature difference. The plate thickness and material of the work W are fixed, and predetermined coefficients (KT and K) obtained from experiments, experience, and calculations.
It is represented by F).

The amount of conduction heat (QF) is the work W.
Since heat conduction is not performed at the end portion (peripheral edge portion) or the cut portion, it changes depending on the shape and cutting locus of the work W.

The shape of the work W and the cutting locus depend on the state of the four sides in each section, that is, whether or not the section is in contact with the adjacent section. 0 as variables FL1, FL2, F respectively
It is represented by L3 and FL4.

That is, the amount of heat of conduction (QF) is calculated by the following equation. QF (n, m) = KT * KF * {FL1 (n, m) * (TP (n, m) -TP (n-1, m)) + FL2 (n, m) * (TP (n, m) -TP (n, m-1)) + FL3 (n, m) * (TP (n, m) -TP (n + 1, m)) + FL4 (n, m) * (TP (n, m) -TP (n , M + 1))} n = 1 to N, m = 1 to M. In addition, TP
(N, m) is the previous temperature in each section. If the subscript exceeds the range, that is, outside the section on the work W, the temperature difference is 0 and the corresponding FLx is also 0.

By the way, the above variables FLx (FL1, FL
2, FL3, FL4) are updated at any time according to the movement of the cutting point by the cutting beam V as the cutting work on the work W progresses.

As shown in FIG. 2A, the section where the cutting point is currently located is O (k, j), and the sections surrounding the section O are A, B, C, D, E, and F,
In the case of G and H, the above variables FL1, FL2, FL3 are determined by the combination of the section (previous position) where the cutting point was previously located and the section (next position) to be moved from now on.
FL4 is changed as shown in the table of FIG.

In the table of FIG. 2 (b), each variable F
The state of Lx is expressed by the following symbols 1 to 12. For example, in the symbol 10, only FL1 is 0, and other FL2, FL3, FL4 are 1. 1: FL2 = 0, FL3 = 0, FL4 = 0 2: FL2 = 0 3: FL2 = 0, FL3 = 0 4: FL1 = 0, FL3 = 0, FL4 = 0 5: FL3 = 0, FL4 = 0 6 : FL3 = 0 7: FL1 = 0, FL4 = 0 8: FL1 = 0, FL2 = 0, FL4 = 0 9: FL4 = 0 10: FL1 = 0 11: FL1 = 0, FL2 = 0 12: FL1 = 0 , FL2 = 0, FL3 = 0 where FL1, FL2, FL3 and FL4 are variables of side a, side b, side c and side d in section O shown in FIG. 2 (a), for example, As shown in FIG. 3A, when the cutting point passes from the section F to the section A or the section B, or when the cutting point passes from the section G to the section O to the section A or the section B. When heading,
Regarding the heat conduction, assuming that the side a is cut off and there is no adjacent section, as indicated by reference numeral 10 in FIG.
It is set to 1 = 0.

Further, as shown in FIG. 3B, when the cutting point goes from the section F or the section G to the section C or the section E through the section O, the section adjacent to the side a and the side b in the section O. As shown by reference numeral 11 in FIG. 2B, FL1 = 0 and FL2 = 0 are set.

Further, as shown in FIG. 3 (c), when the cutting point goes from the section F or section G to the section G or section H through the section O, the section A has sides a, b and c. Assuming that there are no adjacent sections, FIG.
FL1 = 0, FL2 = 0, FL
3 = 0 is set.

Amount of heat radiation (QM) for each category of work W
Is proportional to the area (SP) of each section of the work W, is proportional to the temperature difference from the ambient temperature (TO), and changes depending on the surface condition of the work W and the cooling conditions of the work W.

The surface condition of the work W and the cooling condition of the work W are fixed, and are represented by predetermined coefficients (KG and KH) obtained from experiments, experience, and calculations. The area of each section is calculated from SP = X * Y / N / M. That is, the heat radiation amount (QM) is calculated by the following formula. QM (n, m) = KG * KH * SP * (TP (n, m)
-TO) n = 1 to N, m = 1 to M.

The temperature of each section of the work W can be calculated from the temperature change amount = (heat input amount + conduction heat amount−heat radiation amount) / heat capacity based on the previous temperature calculated value.
The heat capacity is uniquely determined from the material of the work W, the plate thickness of the work W, and the area of each section, and has a predetermined coefficient (HM).
Represented by

That is, the calculated temperature value (TP ') this time
Is the previous temperature calculation value (TP), heat input amount (QH), conduction heat amount (QF), heat radiation amount (QM), and heat capacity (HM)
Therefore, TP '(n, m) = {TP (n, m) + QH (n, m)
+ QF (n, m) -QM (n, m)} / HM, which is obtained by the above equation.

The output value of the cutting beam can be obtained from the temperature of the section having the processing point by using the table shown in FIG. For example, when the cutting point is in the section (k, j), the temperature TP
If (k, j) is 40 ℃, the peak output is 1000 (W)
, The duty becomes 98 (%).

Further, the output value TP (k,
j) can also be obtained by the following approximate expression. When TP (k, j) <TA Peak output = 1000
(W) Duty = 100-KD * (TA-TP (k, j)) (%) When TP (k, j)> = TA Peak output = 1000-KT
* (TM-TP (k, j)) (W) Duty = 100-KF * (TM-TP (k, j)) (%) However, TA, KD, KT, KF, TM are constants.

When the output value of the cutting beam V is obtained by the output value determining unit 15, the beam generator 2 is controlled in accordance with the output value as described above, so that the work W from the beam generator 2 is controlled. Therefore, the cutting beam V having an appropriate output is emitted.

As described above, in the cutting processing apparatus 1, the temperature in each section is calculated, and based on the temperature in the section where the cutting point is located, an appropriate heat input to the work W without giving excessive heat input to the work W is performed. Since the target output value of the cutting beam is determined, it is possible to set the optimum cutting beam output for any cutting shape (cutting locus) and also when restarting after processing interruption. The output of the cutting beam can be optimally controlled.

In the above-described embodiment, the temperatures are calculated for all N * M sections, but the range for obtaining the temperature is in the vicinity of the cutting point, that is, the section through which the cutting locus passes and its surroundings. It may be limited to categories. For example, “n = 1 to N, m = 1 to M” in each of the above-mentioned calculation formulas is “n = k−10 to k + 10, m = j−1.
0 to j + 10 ”, and the temperature may be calculated only in the section of ± 10 from the section where the cutting point is located. However, it cannot be denied that the control accuracy is slightly reduced.

Further, the portion (section) cut off by cutting the work W may not be calculated. However, it goes without saying that in this case, an algorithm for confirming the cutoff is required.

On the other hand, when calculating the heat conduction between each section, in the above-mentioned embodiment, FLx = 0 is set when the section is not in contact with the adjacent section, but the above FLx is a coefficient of heat conduction to the air. Replace with KZ, ie FLx = K
By setting Z, the control accuracy can be improved.

Further, in FIG. 1, the numerical control unit 5, the servo control unit 6, the temperature calculation unit 13, and the output value determination unit 15 are shown as independent blocks, respectively. It is also possible to realize the functions of the above respective parts by the CPU, and it is also possible to combine each memory of the numerical control program memory 4, the constant setting memory 10, and the temperature storage memory 14 into one memory.

Further, in the above-mentioned embodiment, each section is made into a quadrangle by dividing the work into a square shape, but the shape of the above-mentioned section is not limited to the quadrangle, and the shapes are arranged without any gaps therebetween. In that case, for example, a triangle or a hexagon can be used. Needless to say, when the shape of the section is not a quadrangle like this, it is necessary to change the above-described calculation method of heat conduction in detail.

Further, the control method according to the present invention is not limited to the cutting apparatus using a laser beam as a cutting beam as shown in the embodiment, and a cutting processing for cutting a work by using various beams such as a plasma beam. Of course, it can be effectively applied to a device.

[0044]

As described above in detail, according to the present invention, the temperature of each section in the work is calculated, and an excessive heat input is given to the work W based on the temperature in the section where the cutting point is located. Since the target output value of a proper cutting beam with no cutting is determined, all cutting shapes (cutting locus)
It is possible to set the optimum output of the cutting beam, and it is possible to optimally control the output of the cutting beam even when the processing is restarted after the interruption. That is, according to the control method of the cutting apparatus according to the present invention, it is possible to prevent excessive heat input to the work in advance, without causing cutting failure due to excessive heat input, to the work. It is possible to carry out cutting work having a complicated shape.

[Brief description of drawings]

FIG. 1 is a conceptual overall view of a cutting device that employs a control method according to the present invention.

2A and 2B are tables showing notation examples of other divisions with respect to the current position of the cutting point, and variable setting manners according to the movement manners of the cutting point according to the division notation.

3 (a), (b), and (c) are conceptual diagrams showing movement modes of cutting points, respectively.

FIG. 4 is a table for obtaining an output value of a cutting beam from the temperature of a section having a cutting point.

FIG. 5 is a conceptual diagram showing an example of a conventional cutting device.

FIG. 6 is a plan view showing an example of a work to be cut.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cutting processing device, 2 ... Beam generator, 3 ... XY table, 3x ... X-axis drive motor, 3y ... Y-axis drive motor, 4 ... Numerical control program memory, 5 ... Numerical control part, 6 ... Servo control part, 10 ... Constant setting memory, 11 ... Timer, 12 ... Temperature sensor, 13 ... Temperature calculating unit, 14 ... Temperature storage memory, 15 ... Output value determining unit, V ... Cutting beam, W ... Work.

Claims (1)

[Claims] 1. A method of controlling a cutting device for cutting a plate-shaped work by a cutting beam, the work being divided into a plurality of adjacent sections, and the material of the work, Using the thickness of the work, the surface state of the work, the output value of the cutting beam, the shape of the cutting beam, the cutting trajectory, the ambient temperature, and the cooling condition of the work, the temperature in each of the sections is predetermined. A cutting processing apparatus comprising: a step of calculating for each time; and a step of controlling the output value of the cutting beam based on the temperature of the section where the cutting point calculated in the step is located. Control method.