JP5971001B2 - Material heat propagation simulation device for thermal cutting machine - Google Patents

Description

  The present invention relates to a material heat propagation simulation apparatus for a heat cutting machine that simulates the state of heat propagation of a material such as a sheet metal by heat input during processing in a heat cutting machine that performs laser cutting, plasma cutting, or the like.

  Conventionally, in laser processing of a sheet metal material, it has been empirically known that heat accumulation due to laser irradiation causes thermal distortion of the material and affects product accuracy.

Japanese Patent No. 4385724

  In the cutting process with a simple shape, the influence of heat is relatively small. For example, in the case of cutting a gear-shaped product w whose outer periphery is a gear-shaped portion wa as shown in FIG. For cutting, a long length is cut in a small range, so the amount of heat input per area of the material W increases. As a result, the material temperature rises and thermal distortion increases. If the processing is continued in a state where the thermal strain is large, a stress due to heat is generated in the material, so that the processing accuracy is lowered, and if the strain is increased to some extent, plastic deformation may occur. Further, in the case of processing a product w having a complicated shape as shown in the figure, since the processing is continued in a state where the material W has the stress caused by the heat, the last part of the outer periphery of the product w is separated from the material W. When the product w is released, the product w may be greatly warped or the like so that the stress is released. When such a large warpage occurs, the laser processing machine having a laser head interference error monitoring function may cause processing to stop.

  Although the above-described accuracy degradation and processing troubles due to thermal strain have been known empirically, it has not been known yet how and under what conditions. Therefore, if the temperature change in each part of the material caused by heat input during processing is known before actual processing, the state of thermal strain can be predicted to some extent, and the material due to thermal strain can be predicted. I thought it would lead to the prediction of deformation.

An object of the present invention is to provide a material heat propagation simulation device for a thermal cutting machine capable of simulating what kind of temperature change occurs in the material as the cutting by the thermal cutting machine progresses.
Another object of the present invention is to perform the simulation of the temperature change with higher accuracy.
Still another object of the present invention is to propose an apparatus having a specific calculation formula that can simulate the temperature change with higher accuracy.
Still another object of the present invention is to make it possible to perform a more accurate simulation of temperature change in consideration of up to a portion melted by the progress of cutting.
Still another object of the present invention is to make the state of temperature change visible.
Still another object of the present invention is to enable simulation of the deformation state of a material due to a temperature change.

The material heat propagation simulation device of the thermal cutting machine according to the present invention is configured to detect a heat propagation state generated in the material (W) in a process of melting and cutting a portion to be cut of a plate-like material by heat input by the thermal cutting machine. A simulation device,
A part or the whole of the material (W) is approximated by voxels so that each voxel (S) has a temperature, and heat is easily transferred between adjacent voxels (S) and between the voxels (S) and the space. Model generation means (4) for creating a voxel model (M) having a diffusion coefficient indicating the degree of the degree;
Cutting area calculation means (5) for calculating an area (Ra) cut per unit time on the cutting path (R) of the material (W);
Heat input voxel calculation means (6) for calculating the voxel (S) to be heat input of the voxel model (M) from the area (Ra) calculated by the cutting area calculation means (5) according to a predetermined rule.
For each voxel (S) to which heat input calculated by the heat input voxel calculating means (6) is applied, the material (W) corresponding to each voxel (S) by heat input at the time of cutting by the thermal cutting machine. A heat input temperature setting means (7) for setting the heat input temperature generated in the site;
Voxel temperature calculation means (8) for calculating the temperature change per unit time using the heat input temperature and the diffusion coefficient (D) for each voxel (S) of the voxel model (M),
With.
The thermal cutting machine is a device that cuts a portion of the material (W) to be cut by heat input, for example, a laser processing machine, a plasma cutting machine, an electron beam processing machine, a gas cutting machine. There are processing machines.

According to this configuration, each model voxel (S) is given a temperature by the model generation means (4), and heat is easily transmitted between the adjacent voxels (S) and between the voxels (S) and the space. A voxel model (M) having a diffusion coefficient (D) indicating the degree is created.
The cutting area calculation means (5) calculates an area (Ra) to be cut every unit time (Δt) on the cutting path (R) of the material (W). The cutting area calculation means (5) obtains machining figure data by analyzing the NC program (13), for example, and calculates the area (Ra) from the machining figure data. Instead of (13), the region (Ra) may be calculated directly from the processed figure data.
The heat input voxel calculating means (6) sets the voxel to be heat input of the voxel model (M) from the area (Ra) calculated by the cutting area calculating means (5) according to a predetermined rule. . This defined rule is that if the line to be the cutting area (Ra) is selected and connected to any voxel (S) arranged in a vertical and horizontal matrix, the line has a shape closer to the above. For example, a Bresenham algorithm is used.
The heat input temperature setting means (7) is configured such that each voxel (S) set by the heat input voxel calculation means (6) is subjected to heat input at the time of cutting by the heat cutting machine. The heat input temperature generated at the portion of the material (W) corresponding to (S) is set.
The voxel temperature calculating means (8) calculates a temperature change per unit time (Δt) for each voxel (S) of the voxel model (M) using the heat input temperature and the diffusion coefficient (D). To do.
By performing each calculation as described above, what temperature change occurs in the material (W) as the cutting result by the thermal cutting machine is obtained as the calculation result of the voxel temperature calculation means (8). Can be simulated.
In this case, heat propagation is completely different between the surface adjacent to the space of the material (W) and the inside of the material. Therefore, two types of diffusion coefficients (D) are determined as described above, and the diffusion coefficient (D) is properly used for the surface in contact with the space and the adjacent surfaces of the voxels, so that the temperature change can be accurately simulated. be able to.
The simulation result may be visualized as an image as described later, or may be used for calculation of deformation of the material (W).

ここで、Δｔ：単位時間（任意に設定する）
Δｘ：ボクセルのＸ軸方向の長さ
ΔＹ：ボクセルのＹ軸方向の長さ
ΔＺ：ボクセルのＺ軸方向の長さ
この数式（１）は、拡散が生じている物質あるいは物理量の密度のゆらぎを記述する微分方程式であり、熱の伝播もこの方程式に従う。この発明は、この拡散方程式を用い、この方程式内の拡散係数として、素材（Ｗ）内と境界とで異なるものを用いる工夫を図ることで、板状の素材（Ｗ）における熱切断における熱伝播状況のシミュレーションを実現したものである。
この数式（１）を用いることで、精度の良い前記温度変化のシミュレーションを具現化できる。 As described above, when a plurality of diffusion coefficients (D) are used, the voxel temperature calculation means (8) uses a discretized diffusion equation (that is, a heat conduction equation) represented by the following equation (1). line the calculation of the temperature Te intends.

Here, Δt: unit time (set arbitrarily)
Δx: Length of voxel in the X-axis direction
ΔY: Voxel length in the Y-axis direction
ΔZ: Length of voxel in the Z-axis direction This equation (1) is a differential equation describing the density fluctuation of the substance or physical quantity in which diffusion occurs, and the propagation of heat follows this equation. The present invention uses this diffusion equation, and devise to use a different diffusion coefficient in the equation between the material (W) and the boundary, thereby allowing heat propagation in thermal cutting in the plate-shaped material (W). This is a simulation of the situation.
By using this mathematical formula (1), it is possible to realize a highly accurate simulation of the temperature change.

When using the above equation (1) and regardless of whether the above equation (1) is used or not, when using different diffusion coefficients (D) between the material (W) and the boundary as described above The voxel temperature calculation means (8) preferably calculates the temperature per unit time (Δt) using each voxel (S) in the cut region (Ra) as a space.
In the thermal processing, since the cut portion of the material (W) is melted away, each voxel (S) that becomes the cut region (Ra) changes its temperature by calculating heat propagation as a space. This simulation can be performed with higher accuracy.

In this invention, the temperature change visualization for displaying the temperature of each voxel (S) calculated by the voxel temperature calculation means (8) on the screen of the image display device (3) as an image that changes as the cutting time elapses. Means (9) may be provided . Visualization of the temperature change is performed by, for example, changing the shade or hue so that the high temperature portion on the voxel model (M) is red and the low temperature portion is blue.
If the temperature of each voxel (S) is displayed on the screen of the image display device (3) as an image that changes as the cutting time elapses, how the temperature of the material (W) changes as the cutting progresses However, it can be recognized by the visual observation of the operator. By recognizing this change, the operator can appropriately determine whether or not the thermal cutting process can be performed appropriately.

In the present invention, there may be provided material shape change calculating means (10) for calculating the deformation state of the material (W) according to a rule determined by using the temperature value calculated by the voxel temperature calculating means (8). . For example, in the voxel model (M), the determined rule is that a model in which each voxel (S) of the cut region (Ra) is a space is a shape of the material (W), and a line of the material (W) A deformation state of the material (W) is calculated using a material such as an expansion coefficient and an elastic coefficient and the value of the temperature. This deformation state may be calculated as a state in which deformation is constrained and distortion is generated.
If the temperature change of each part of the material (W), the shape of the material (W), the linear expansion coefficient of the material (W), the elastic coefficient, etc. are used, the deformation state of the material (W), that is, the shape after deformation, The state of occurrence can be calculated. If the deformation state of the material (W) is known, this is visualized and displayed on the screen, so that the operator can determine whether or not appropriate processing can be performed more appropriately than when only the temperature change is recognized. be able to. Further, by using numerical data of the deformation state, for example, numerical data of how much the deformed portion protrudes from the upper surface of the material (W) before the deformation, and comparing with the set allowable range, appropriate processing can be performed. Automatic determination of whether or not it can be performed.

  The material heat propagation simulation device for a thermal cutting machine according to the present invention is a device for simulating a heat propagation state generated in the material in the process of melting and cutting a portion to be cut of a plate-like material by heat input by the heat cutting machine And a diffusion coefficient indicating the degree of heat transfer between adjacent voxels and between voxels and space by approximating a part or the whole of the material to voxels and giving each voxel a temperature. From the model generation means for creating the given voxel model, the cutting area calculation means for calculating the area to be cut per unit time on the cutting path of the material, and the area calculated by the cutting area calculation means, The heat input voxel calculation means for calculating the voxel to be heat input of the voxel model according to a predetermined rule and the heat input voxel calculation means A heat input temperature setting means for setting a heat input temperature generated in a part of a material corresponding to each voxel by heat input at the time of cutting by the thermal cutting machine, and each of the voxel models Since the voxel includes a voxel temperature calculating means for calculating a temperature change per unit time using the heat input temperature and the diffusion coefficient, any temperature change in the material according to the progress of cutting by a thermal cutting machine Can be simulated.

Since the voxel temperature calculation means calculates the temperature using the diffusion equation (1) , the temperature change simulation can be realized with higher accuracy.
When the voxel temperature calculation means calculates the temperature per unit time using each voxel in the cut area as a space, the temperature change with higher accuracy considering the part melted by the progress of cutting. Simulation is possible.
The calculated the temperature of each voxel in the voxel temperature calculating means, the screen of the image display apparatus, if equipped with a temperature change visualizing means for displaying an image which changes with the passage of the cutting time, visually the status of the temperature change Can be recognized.
When the material shape change calculation means showing the deformation state of the material according to the rule determined using the temperature value calculated by the voxel temperature calculation means is provided , the deformation state of the material due to the temperature change can be simulated. .

It is a block diagram which shows the conceptual structure of the raw material heat | fever propagation simulation apparatus of the heat cutting processing machine which concerns on one Embodiment of this invention. It is a top view which shows a part of the raw material used as the simulation object, and the example of a product shape. It is explanatory drawing of voxelization and thermal diffusion by the simulation apparatus. It is explanatory drawing of the process of each process in the simulation apparatus. It is the schematic of the example of an input screen of the simulation apparatus. It is the schematic of the example of an output screen of the simulation apparatus. It is explanatory drawing which shows the problem of the deformation | transformation in the example of a thermal cutting process, and the example.

  An embodiment of the present invention will be described with reference to FIGS. This material heat propagation simulation device is a device for simulating a heat propagation state generated in the material W in a process of melting and cutting a portion to be cut of the plate-like material W by heat input by a heat cutting machine. This material heat propagation simulation apparatus comprises the following function achievement means by an information processing apparatus 1 (including an operation program) such as a personal computer and a program (not shown) executed thereon. .

  The information processing apparatus 1 includes or is connected to an input device 2 such as a keyboard, a mouse, and a touch panel and an image display device 3 that displays an image such as a liquid crystal display device. The thermal cutting machine is a device for cutting by heat cutting, that is, a part to be cut of a material by heat input, for example, laser processing machine, plasma cutting machine, electron beam processing machine, gas cutting machine, etc. There is. This embodiment is an example of a laser processing machine. The material W is an iron plate.

  The simulation apparatus includes, as the above-described function achievement means, model generation means 4, cutting area calculation means 5, heat input voxel calculation means 6, heat input temperature setting means 7, voxel temperature calculation means 8, temperature change visualization means 9, and A material shape change calculating means 10 is provided.

  The model generation means 4 creates a voxel model M in which a part or the whole of the material W is approximated by voxels. The voxel model M is a model in which the modeling target range of the material W is divided into cubic voxels S arranged in the three-dimensional directions of front and rear, left and right, and top and bottom. One voxel S is assumed to have uniform properties and physical quantities. In this example, the voxel S is assumed to have temperature as its properties and physical quantities. Further, the model generating means 4 gives respective diffusion coefficients between the voxels S and between the voxels S and the space. The diffusion coefficient is a coefficient indicating the degree of ease of heat transfer to the adjacent voxel S. More specifically, the diffusion coefficient indicates a temperature that passes through a unit area per unit time.

  As the size of one side of one voxel S can be reduced, a more accurate simulation can be performed. However, if the size is reduced, the amount of calculation increases and the calculation time becomes longer. Set to Further, the dimensions of the voxel S can be arbitrarily changed within the setting range by the input setting. In the case of cutting the product w having the gear-shaped portion wa on the outer periphery as shown in FIG. 7, at least the shape of the gear-shaped portion wa is a voxel S having a size that can be represented by the arrangement of the voxels S.

The range E of the material W as the voxel model M may be set arbitrarily. However, this embodiment is an example applied to a cutting process in which a plurality of products w having the same shape are cut from the material W, and FIG. As shown in FIG. 3, the range is a predetermined rectangle including one product w and its periphery. FIG. 2 (B)
In addition, as described later, it may be a range including a plurality of adjacent products w and their surroundings. Note that the range E as the voxel model M is a range in which at least one voxel S exists on the outer periphery of the product w when applied to the cutting of the product w. This is to calculate the melted voxel S as a space as will be described later.
The automatic setting of the range E as the voxel model M will be described later with reference to FIG.

  The cutting area calculation means 5 is a means for calculating an area to be cut per unit time on the cutting path of the material W. FIG. 4B shows a region Ra to be cut during the unit time Δt from time t to t + Δt on the cutting path R indicated by a thin line, and the position at time t and time t + Δt is indicated by a black circle. Shown with dots. The unit time Δt may be set arbitrarily and is preferably freely changeable by an input operation.

  In the cutting area calculation means 5, the cutting path R is obtained by analyzing the NC program 13 (FIG. 1, FIG. 4 (A)) for performing the thermal cutting processing of the product w. The NC program 13 has a command of a coordinate position or a movement distance for moving a laser head (not shown) relative to the material W, and the cutting path R can be analyzed from these commands. The cutting area calculation means 5 may recognize the cutting path R from graphic data such as CAD data, or may recognize from the NC program 13 and graphic data.

  The heat input voxel calculating means 6 is a means for calculating the voxel to be heat input of the voxel model M from the region R calculated by the cutting region calculating means 5 according to a predetermined rule. The predetermined rule is a rule calculated by the Bresenham algorithm, for example. Specifically, among the discretized voxels S, the voxel S is selected so as to show a straight line or a curve indicating the region R when the selected voxels S are connected. In other words, the calculation is performed as to which voxel S arranged in a matrix on the plane looks like a curve indicating the region Ra. Therefore, as can be seen from the example of FIG. 4C, there may be a voxel S that is not selected even if it is in the region R.

The heat input temperature setting means 7 is configured such that each voxel S to be heat input set by the heat input voxel calculation means 6 has a material portion corresponding to each voxel S by heat input at the time of cutting by the thermal cutting machine. It is a means for setting the heat input temperature generated in. This heat input temperature can be set to an arbitrary temperature from the input device 2, for example. Further, the heat input to the voxel S is determined so that there is an input difference between the front surface and the back surface of the material W. For example, as shown in FIG. 4 (D), the heat input temperature setting means 7 displays a heat input temperature entry field A and a temperature drop entry field B on the screen of the image display device 3, The temperature entered in the temperature entry column A is the temperature of the voxel S on the most front side of the input voxels S. Hereinafter, the voxel S closer to the back side is entered in the entry column B for the temperature drop. The temperature is set in the voxel S of the entire material thickness so that the temperature decreases linearly in sequence.
Specifically, the temperature drop entry column B is filled with the temperature drop per unit depth ΔZ from the material surface. The heat input temperature setting means 7 calculates the temperature of each voxel S in the Z-axis direction from the temperature drop per unit depth ΔZ, and sets the calculated temperature in the voxel S.

  The voxel temperature calculating means 8 is a means for calculating a temperature change per unit time Δt for each voxel S of the voxel model M using the heat input temperature and the diffusion coefficient. In this case, the propagation of heat is calculated so as to exchange heat with the adjacent voxels S as shown in FIG. 3B. Adjacent voxels S are six voxels S of front and rear, left and right, and upper and lower. This is a calculation method based on the “cell automaton discrete calculation model”.

ここで、Δｔ：単位時間（任意に設定する）
Δｘ：ボクセルのＸ軸方向の長さ
Δｙ：ボクセルのＹ軸方向の長さ
Δｚ：ボクセルのＺ軸方向の長さ
である。
添字ｉ，ｊ，ｋは、ボクセルモデルＭの原点となる角Ｏ（図３（Ａ））から、直交する３軸（Ｘ，Ｙ，Ｚ軸）方向に並ぶボクセルＳの並び順を示す。ａ，ｂ，ｃおよびｄ，ｅ，ｆは、ｉ，ｊ，ｋの任意の値である。
ｎは単位時間Δｔ当たりの個数、換言すれば各単位時間Δｔに付した順番であり、
次の関係を表す。

The calculation of the temperature change by the voxel temperature calculation means 8 is specifically performed according to the following three-dimensional discretized diffusion equation.

Here, Δt: unit time (set arbitrarily)
Δx: Length of voxel in the X-axis direction
Δy: length of voxel in Y-axis direction
Δz: the length of the voxel in the Z-axis direction.
The subscripts i, j, and k indicate the arrangement order of the voxels S arranged in the direction of three orthogonal axes (X, Y, and Z axes) from the angle O (FIG. 3A) that is the origin of the voxel model M. a, b, c and d, e, f are arbitrary values of i, j, k.
n is the number per unit time Δt, in other words, the order given to each unit time Δt,
Represents the following relationship:

  The diffusion coefficient D in the diffusion equation is discretized as a different value in the material W and the boundary (boundary between the material W and the space). As the diffusion coefficient D, two types, a value having a value in the material W and a value having a boundary value, are determined, and for each surface of the cell S characterized by the symbols i, j, and k, A diffusion coefficient D determined according to whether it is within the material or the boundary is used.

この式を３次元に展開すると、上記の（１）式となる。 The establishment of the three-dimensional diffusion equation (1) will be described. The one-dimensional diffusion equation can be discretized as the following equation (2).

When this expression is expanded three-dimensionally, the above expression (1) is obtained.

  This equation (2) is a partial differential directional equation describing the density fluctuation of a substance or physical quantity in which diffusion occurs, and it is known that the propagation of heat follows this equation. Therefore, in this embodiment, “f” in the above equation is replaced by density to temperature, and development in three dimensions is performed, and the above equation (1) is obtained.

  Further, the voxel temperature calculation means 8 assumes that the path portion indicated by the arrow in FIG. 3A is a region Ra that has been cut during the unit time Δt, and heats the region Ra to cut it. In the calculation of thermal diffusion when processed, it is treated as a voxel S that receives heat, but in the calculation of thermal diffusion when cutting the subsequent area, it is calculated as a part that has melted away, that is, a space (outside air layer). To do. The width regarded as a space is, for example, one row of voxels S.

  In this way, the voxel temperature calculation means 8 calculates the temperature change due to thermal diffusion, assuming that the heat input processing is sequentially performed on all the regions on the cutting path R.

  The temperature change visualization means 9 is an image that changes the temperature of each voxel S calculated by the voxel temperature calculation means 8 on the screen of the image display device 3 as the cutting time elapses, for example, as shown in FIG. indicate. This figure is an example of an image showing the temperature of each part at a certain point of time in the voxel model M displayed by the temperature change visualization means 9. In the figure, three types of images are displayed: an image Ga showing the temperature distribution when the voxel model M is viewed from the upper surface serving as the heat input surface, and images Gb and Gc showing the temperature distribution in the X-axis cross section and the Y-axis cross section. ing. In the image Ga showing the temperature distribution viewed from the upper surface, for example, the high temperature portion is red and the low temperature portion is blue, and the density and hue are changed according to the temperature. In the images Gb and Gc showing the temperature distribution in the X-axis cross section and the Y-axis cross section, the axial position on the cross section and the temperature are taken as two axes, and the temperature is shown as a graph. The position of each cross-section is the position indicated by the cross-line cursor shown on the image Ga viewed from above. By moving the cursor, the temperature of an arbitrary cross-section to be moved is displayed.

  Further, the temperature change visualization means 9 can display the images Ga, Gb, Gc so as to change at an arbitrary double speed as the processing time elapses, and can display a still image at an arbitrary time. The image Ga showing the temperature distribution seen from the upper surface can be displayed by designating not only the uppermost layer but also the temperature of an arbitrary layer of voxels S in the plate thickness direction (Z-axis direction).

The material shape change calculating means 10 is a means for calculating the deformation state of the material W according to a rule determined using the temperature value calculated by the voxel temperature calculating means 9. For example, in the voxel model M, the determined rule is that the voxel model M in which each voxel S in the cut region is a space is a material shape, and the material such as a linear expansion coefficient and an elastic coefficient of the material and the temperature Is used to calculate the deformation state of the material. As for the linear expansion coefficient and elastic coefficient of the material, the coefficient corresponding to the material is registered in the material shape change calculating means 10 or other appropriate means, and the material described in the NC program 13 is registered as described above. Use the coefficient of linear expansion and elastic modulus obtained by comparing with the material. When it is not registered or when the material is not described in the NC program 13, it is input on an arbitrary input screen or the like.
The material shape change calculation means 10 has a material change visualization unit (not shown), and displays the shape of the deformed voxel model M specified by the deformation calculation result on the screen of the image display device 3. It can be displayed.

In FIG. 1, an output processing means 12 is a means for performing processing for displaying as an image on the image display device 12 in accordance with the output and request of each means 4-11 constituting the material heat propagation simulation apparatus.
The input processing means 11 displays an input screen on the image display device 3 via the output processing means 12, stores the data input from the input device 2, and stores the stored data in the material heat propagation simulation device. It is a means given to each means 4-10 to comprise according to a request | requirement.

FIG. 5 shows an example of the input screen. This screen also serves as an operation screen for displaying a desired screen when inputting data necessary for the simulation and displaying the result after the simulation.
In this example of the input screen, as can be seen from the illustrated content, the material and thickness of the material W and the size of the voxel model (the number of voxels in each axial direction of the voxel model) are displayed, and the displayed content is displayed from the input device 2. It can be changed by operation. Since the material and the plate thickness are generally described in the NC program 13 (FIG. 1), the values are read from the NC program 13 and displayed. In the same figure, the letter “cell” indicates a voxel. The cell size (number of voxels in each axial direction of the voxel model) is displayed as a default value, and the number of voxels in each axial direction can be arbitrarily changed within a predetermined range.
In addition, on this input screen, the diffusion coefficient inside the material and the diffusion coefficient at the boundary can be set, and the dimensions Δx, Δy, Δz of each voxel S in each axial direction and the unit time Δt are displayed. The Default values are also displayed for these two types of diffusion coefficients and the values of Δx, Δy, Δz, and Δt, and can be arbitrarily changed within a predetermined range.

  In addition, the input screen displays the initial material temperature, the outside air temperature, the heat input temperature (surface), and the temperature drop per unit time Δt, and can be input. On this input screen, an image Gw indicating the shape of the product w processed by the NC program 13 is also displayed on any of the screens.

  As the display for the operation after the simulation, "Redraw", "Rewind", "Frame advance", "Play", "Processing status", "Temperature distribution", "Strain distribution" are displayed as software keys. By selecting a desired software key, the material heat propagation simulation apparatus performs processing corresponding to the key.

Next, processing and input operations of this material heat propagation simulation apparatus will be described in the order of processing.
First, the NC program 13 is read by the input processing means 11, and necessary data is input from the input screen described with reference to FIG. In particular, when no change is input, a default value is used.

In the simulation process, the voxel model M is generated by the model generation means 4.
The setting of the range E as the voxel model M by the model generation means 4 may be performed automatically according to a predetermined rule, or may be performed by an input from the input device 2 by an operator or the like. In the case of performing automatically, for example, as shown in FIG. 2B, from the graphic data of the cutting path R analyzed from the NC program 13 or the graphic data such as CAD data, the processed figure wg that becomes the product w And a minimum rectangle RE in which the processed figure wg is accommodated on the outer periphery of the processed figure wg is obtained. A range obtained by taking a predetermined margin range (margin) on the outer periphery of the minimum rectangle RE is defined as a range E as a voxel model M. Note that FIG. 2B defines a minimum rectangle RE including two processed figures wg. When the minimum rectangle RE is obtained for each processed figure wg, if a plurality of processed figures wg are close to each other such that the margin range partially overlaps, a group of processed figures wg in which the overlapped portion is generated. The minimum rectangle RE is obtained around the periphery as shown in the figure, and a range in which the margin range is provided on the outer periphery thereof is set as a range E as a voxel model M. The means for analyzing the cutting path R from the NC program 13 may be shared with the cutting path calculation means 5R.

Next, the cutting area R is calculated by the cutting area calculation means 5 from the read data of the NC program as shown in FIG. 4B, and the cutting area Ra for each unit time Δt in the cutting path R is calculated. The
Next, the heat input voxel S that is the voxel S corresponding to the cutting path R is calculated by the heat input voxel calculating means 6 as shown in FIG. When the heat input voxel S is determined, the heat input temperature is set to each heat input voxel S by the heat input temperature setting means 7. As described above, the heat input temperature is the highest in the uppermost layer of the voxel S and is set to a lower temperature as going to the lower layer (lower side).

  The voxel temperature calculation means 8 calculates the temperature of each voxel S using the above-described diffusion equation (1) using the set heat input temperature. The cutting path R for one product w is calculated by calculating the cutting area Ra every unit time Δt in the cutting path R, setting the heat input temperature, and calculating the voxel temperature using the diffusion equation (1). It repeats sequentially according to the processing order over the whole. The unit time Δt is, for example, 1 second. In this case, only the heat input voxel S, which is the first region Ra, has a high temperature at the first time, and the other voxels S calculate the propagation of heat during the unit time Δt as the initial material temperature. In the second and subsequent times, the voxel S that has entered heat before the previous time is replaced with a space (outside air layer), and each voxel S has the temperature calculated in the previous calculation of heat propagation, and enters the new cutting region Ra. Calculate by giving temperature. In this way, calculation is sequentially performed for the entire cutting region Ra of the cutting path R.

  The temperature of each voxel S calculated in this way is displayed on the screen of the image display device 3 by the temperature change visualization means 9 as an image that changes as the cutting time elapses as illustrated in FIG. Further, the deformation state of the material W is calculated by the material shape change calculating means 10 from the temperature of each voxel S calculated as described above. The shape of the deformed material is displayed on the screen of the image display device 3.

According to the material heat propagation simulation apparatus of the thermal cutting machine having this configuration, each means 4 to 10 performs calculation and processing by approximating the voxel as described above, so that the material W can be processed according to the progress of cutting by the thermal cutting machine. It is possible to simulate what kind of temperature change occurs.
In this case, since the above diffusion equation (1) is used, an accurate simulation can be performed. When the above diffusion equation (1) is used, two types of heat diffusion coefficient D are used for the in-material and for the interface between the space and the propagation in the actual material and the propagation in the interface. Therefore, it is possible to reflect an appropriate diffusion according to the temperature, and it is possible to perform a temperature change simulation more accurately.
In particular, since the voxel temperature calculation means calculates the diffusion using each voxel S in the cut area as a space, the temperature change simulation can be performed with higher accuracy.

  The calculation result of the temperature change is displayed by the temperature change visualization means 9 as an image that changes as the cutting time elapses, so that the operator can recognize how the temperature of the material changes as the cutting progresses. By recognizing this change, the operator can appropriately determine whether or not the thermal cutting process can be performed appropriately.

  Also, since the material shape change calculation means 10 calculates the deformation state of the material W using the temperature value calculated by the voxel temperature calculation means 8 and displays it as an image, whether or not appropriate processing can be performed. However, it can be judged by the operator more appropriately than when only the temperature change is recognized. In addition, by using numerical data of the deformation state, for example, numerical data of how much the part deformed above the material protrudes from the upper surface of the material before deformation, and comparing with the set allowable range, appropriate processing Automatic determination of whether or not can be performed.

3 ... Image display device 4 ... Model generation means 5 ... Cutting area calculation means 6 ... Heat input voxel calculation means 7 ... Heat input temperature setting means 8 ... Voxel temperature calculation means 9 ... Temperature change visualization means 10 ... Material shape change calculation means 13 ... NC program E ... Range Ga, Gb, Gc ... Image M ... Voxel model S ... Voxel W ... Material w ... Product

Claims (4)

An apparatus for simulating the heat propagation state generated in the material in the process of melting and cutting the portion to be cut of the plate-like material by heat input by a thermal cutting machine,
Voxel that approximates a part or the whole of the material to give a temperature to each voxel, and has a diffusion coefficient indicating the degree of heat transfer between adjacent voxels and between voxels and space. A model generation means for creating a model;
Cutting area calculation means for calculating an area to be cut every unit time on the cutting path of the material,
From the area calculated by the cutting area calculation means, heat input voxel calculation means for calculating voxels to be heat input of the voxel model according to a predetermined rule;
The heat input temperature for setting the heat input temperature generated at the part of the material corresponding to each voxel by the heat input at the time of cutting by the thermal cutting machine, to each voxel to be heat calculated by the heat input voxel calculating means Setting means;
Voxel temperature calculating means for calculating a temperature change per unit time using the heat input temperature and the diffusion coefficient for each voxel of the voxel model,
For example Bei the door,
The voxel temperature calculating means calculates the temperature using the following equation (1):

Here, Δt: unit time (set arbitrarily)
Δx: Length of voxel in the X-axis direction
ΔY: Voxel length in the Y-axis direction
ΔZ: Voxel length in the Z-axis direction
Material heat propagation simulation equipment for thermal cutting machines. The voxel temperature calculating means, the pre-cut area thermal cutting machine the material heat propagation simulation apparatus according to claim 1, wherein the calculation of the temperature of each of the unit time of each voxel as a space. Wherein the calculated the temperature of each voxel in the voxel temperature calculating unit, on the screen of the image display apparatus, according to claim 1 or claim 2, wherein with a temperature change visualizing means for displaying an image which changes with the passage of the cutting time Material heat propagation simulation equipment for thermal cutting machines. Using the value of the calculated voxel temperature calculating means temperature, the stipulated rules to any one of the material shape changes calculated claims 1 to 3 comprising means for calculating a state of deformation of the material The material heat propagation simulation device for the described thermal cutting machine.

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