JPH07239221A - Bending angle detector and linear extracting device and device for setting bending angle detection position therefor - Google Patents

Abstract

PURPOSE:To detect bending angle of a work with high accuracy by referring to data on an acutual tilt angle corresponding to the tilt angle and position of a test piece that has an already-known tilt angle in advance. CONSTITUTION:A laser light is projected onto a calibration block as a test piece while it is held at a specified position and angle and a projecting picture on the calibration block is sensed by a CCD camera 9. Then, the tilt angle and position of the projecting picture on its screen are obtained to calculate the correction quantity of work angle. A calibration table is prepared based on many data thereafter. Then, the picture of an objective work to be sensed by the CCD camera 9 is displayed on a monitor television 11 through a calculation part 10 and at the same time it is stored as a picture data in a recording part 12. The picture data is inputted by an inputting part 13 and computed by the part 10 referring to the table data of the calibration table, etc., storing in a storage part 12, thereby obtaining a bending angle of the work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending angle detecting device for detecting a bending angle when a plate-like work is bent to a required angle, a straight line extracting device used for the bending angle detecting device, and a bending angle of the work. At this time, the present invention relates to a bending angle detection position setting device for setting the detection position.

[0002]

2. Description of the Related Art Conventionally, as a bending angle detecting device in a bending machine such as a press brake, (a) a contact type device for detecting a bending angle of a workpiece by bringing a probe into contact with an inclined surface of the workpiece (eg, (JP-A-1-273618) and (b) A plurality of distance sensors such as an eddy current sensor, an electrostatic capacitance sensor, and an optical sensor are provided, and the distance sensor measures the difference in distance to the work. Non-contact type ones for detecting the bending angle of a work (eg, JP-A-63-49327, JP-A-64-2723, JP-A-1-271013) are known.

However, these conventional bending angle detecting devices have the following problems. That is, in the case of a contact type detection device, it is difficult to apply it to a work with a short leg length because it requires a relatively long bending leg length in order to secure the measurement accuracy of the bending angle, and when it is used for a long period of time, it can be measured. The child wears and deforms due to contact with the work, and the measurement accuracy decreases. Also, in the case of non-contact type detection device, the distance to the work bent by multiple distance sensors is measured and calculated, but it is sufficient because the distance between each distance sensor cannot be long. Accuracy cannot be obtained. In the case of using the above-mentioned eddy current sensor and capacitance sensor, the output changes depending on the material of the work, so that the measurement condition must be changed every time the material changes. On the other hand, in the case of using the optical sensor, the irradiated light is scattered depending on the surface state of the work, and the measurement error is increased or the measurement accuracy is lowered, and the measurement accuracy depends on the resolution of the sensor or the receiver. .

In order to solve these problems, in JP-A-4-145315, the surface of the work is irradiated with slit light or spot light of two points, and the image drawn on the surface of the work is captured by an image pickup means. A bending angle detection device has been proposed which detects a bending angle by processing. That is, as shown in FIG. 28, the optical axis incident on the image pickup means (camera) is arranged so as to be located in a plane perpendicular to the irradiation surface of the work W, and the surface of the work W is irradiated. Slit light (or 2
Assuming that the beam direction angle of the spot light) is α, the angle formed by the slit light on the image is θ ′, and the bending angle of the work W (hereinafter referred to as “work angle”) is θ, the length shown in the figure is obtained. The following equation is established using the heights d, h, and l. tan θ ′ = d / l ... (a) tan θ = h / l ... (b) tan α = d / h ... (c) Formula (a), Formula (b), (c) From the formula, tan θ ′ = d / l = d / h · h / l = tan α · tan θ ··· (d) Since the beam direction angle α is known in the formula (d), the angle θ ′ is determined by image processing. By detecting, the work angle θ can be calculated.

As an image processing technique, there is known a linear approximation processing device which extracts a linear component from a binary image, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-62683. In the linear approximation processing device described in this publication, the number of pixels is reduced for a given binary image without breaking the linear approximation of the binary image, and the binary image is processed based on the remaining number of pixels. A straight line component composed of the value image is extracted.

On the other hand, Japanese Patent Publication No. 4-70091 discloses a device in which a detecting device attached to a press brake can be selectively and freely moved when the bending angle of a work is detected by using the bending angle detecting device. Has been done.

[0007]

[Problems to be Solved by the Invention]
In the calculation of the work angle θ using the equation (d),
The field of view of the camera as a means is expanded by the lens (image
Angle to obtain the work angle θ accurately
Has proved to be difficult. Sanawa
The angle θ ′ between the work angle θ and the slit light on the image
Considering the influence of the angle of view of the lens, the relationship with
Is not so simple, and the work angle θ can be calculated more accurately.
The distance between the camera and the work_a， Focus of lens
Consider various parameters such as point distance f and image receiving element size w
Considered function (optical conditions) F (α, l _a, F, w, ...
・ ・) Need to be brought in. In this case, equation (d) is
It becomes like a formula. tan θ ′ = F (α, l_a, F, w, ...) ・ tan θ ... (e)

[0008] To obtain a work angle θ by using the equation (e), the function _{F (α, l a, f} , w, ···) it is conceivable determined by mathematical methods, and thus In that case, the error becomes large because the variation of the individual such as the lens cannot be taken into consideration. For this reason, it is required to experimentally obtain these various parameters for each device, but it is extremely difficult to perform strict measurement in the optical system. Further, since the distance l _a between the camera and the work, which is one of the parameters, changes depending on the bending conditions (die size, plate thickness, etc.), _a separate means for measuring this distance l _a is required. , The mechanism becomes complicated.

In addition, when the image (linear light projection image) drawn on the surface of the work is captured by the image pickup means and image processing is performed, there are the following problems. That is, in the image measurement in the realization field, the optimum threshold for binarization varies due to the influence of external light and the instability of the light source. It will change. In addition, due to uneven color on the surface of the work and irregular beam reflection due to rolling marks peculiar to the steel plate, the bright area may not be straight, or the edges may be uneven, or as shown in FIG.
As shown in FIG. 9, holes B are formed in the bright area A, and it becomes difficult to obtain a sufficiently thin linear image. As a result, as shown in FIG. 30, the image C after thinning by image processing has a waveform portion and whiskers (short straight line portions) D, and these waveform portions, whiskers and the like extract representative straight lines. It will cause the above error.

Further, when actually bending a work using the upper and lower molds, not only a flat work is captured as an image, but a work having a bent portion is bent. In this case, the bent part of the work may be imaged on the camera, or a part of the lower die may be imaged. Binarization processing and thinning processing were performed based on such images. In this case, an error occurs in the position of the center of gravity and the inclination of this image.

On the other hand, when the bending angle of the work is detected by using the bending angle detection device, it may be impossible or difficult to detect the bending angle depending on the shape of the work or the shape of the bent product. Conventionally, the information related to such a bending angle detecting device has not been considered as control information of the NC device. For this reason, there is a problem that it is difficult to perform processing control using the NC device in a bending machine equipped with such a bending angle detection device.

The present invention has been made in view of the above-mentioned problems, and it is possible to detect the bending angle of a work with high accuracy without performing complicated calculation and without complicating the mechanism. It is an object of the present invention to provide a bending angle detecting device capable of performing the above.

Further, the present invention relates to a straight line extracting device used in such a bending angle detecting device, and an object thereof is to enable a representative straight line to be accurately extracted from a linear image. To do. Further, the present invention relates to a straight line extracting device also used in the bending angle detecting device, so that even when a portion other than the work is captured as an image, only the necessary straight line can be extracted. The purpose is to do.

A further object of the present invention is to enable the bending angle detection position to be set smoothly when the bending angle of a workpiece is detected by the bending angle detection device.

[0015]

In order to achieve the above-mentioned object, a bending angle detecting device according to the present invention is a bending angle detecting device for detecting a bending angle of a work by image processing. Projecting means for forming a linear projected image on the surface of the work by projecting light at a projection angle, (b) imaging the surface of the work on which the linear projected image is formed by the projecting means. Image pickup means, (c) Light projection image detection means for detecting the tilt angle and position of the linear light projection image on the image picked up by this image pickup means, (d) Test piece having a known tilt angle in advance The storage means for storing data relating to the actual tilt angle of the test piece corresponding to the tilt angle and position on the image of the test piece obtained by imaging Inclination angle of the linear projection image detected Based on the a position, and further comprising a calculating means for calculating the bending angle of the workpiece by referring to the data stored in the storage means.

The straight line extracting device used in the bending angle detecting device according to the present invention is, firstly, a straight line extracting device for extracting a representative straight line of a bright portion region from a multi-valued image having a straight bright portion region. Then, (a) a brightness value detecting means for detecting a brightness value of each pixel forming the multi-valued image, and (b) a predetermined value of a screen coordinate system from a distribution of the brightness value of each pixel detected by the brightness value detecting means. Representative pixel calculating means for calculating a representative pixel associated with the optical axis of the bright area along the coordinate axis of (1) and repeating this calculation along another coordinate axis having a predetermined distance from the coordinate axis to calculate a plurality of representative pixels. And (c) a representative straight line calculating means for calculating a representative straight line in the bright area from a plurality of representative pixels calculated by the representative pixel calculating means.

Further, the straight line extracting device used in the bending angle detecting device according to the present invention secondly (a) projects a work and a part of the lower die on which the work is placed at a predetermined projection angle. A light projecting means for forming a linear light projected image on the surfaces of the work and the lower die; and (b) a surface of the work and the lower die on which the linear light projected image is formed by the light projecting means. Image pickup means for picking up an image, (c) binarization and thinning of the image picked up by this image pickup means to represent a set of dot rows in units of one pixel, (d) by this point row forming means Based on the straight line component extracted by the straight line component extracted by the straight line component extraction means for extracting the straight line component related to the image of the work connected to the straight line component related to the image of the lower mold from the obtained point sequence, and (e) Image taken by the imaging means Is characterized in further comprising a projected light image detecting means for detecting an inclination angle and position of the linear projected light image of the workpiece in.

The bending angle detection position setting device according to the present invention is a bending angle detection position setting device for setting the detection position when the bending angle of the work is detected by the bending angle detection means. Bending of the work by the bending angle detection means based on the simulation information calculated by the simulation information calculation means for calculating simulation information relating to the bending state of the work for each bending step from the processing conditions, and (b) the simulation information calculation means. It is characterized in that it comprises an angle-detectable step calculation means for calculating a bending step capable of detecting an angle.

[0019]

In the bending angle detecting device according to the present invention, a linear projection image is formed by projecting light at a predetermined projection angle on the surface of a work which is bent to a required angle, and the linear projection image is formed. The light image is picked up by the image pickup means, and the tilt angle and position of the linear light projection image on the picked-up image are detected by the light projection image detection means. On the other hand, in the storage means, data relating to the actual tilt angle of the test piece corresponding to the tilt angle and the position on the image of the test piece obtained by imaging the test piece having a known tilt angle in advance. Is remembered. By referring to these stored data from the inclination angle and the position of the linear projection image detected by the projection image detection means, the bending angle of the work is calculated by the calculation means. Therefore, the bending angle of the workpiece can be calculated with high precision without performing complicated calculations, and by controlling the upper die or the lower die of the bending machine based on this calculation result, highly accurate bending can be achieved. Processing can be realized.

The data stored in the storage means is
It can be the data of the correction amount of the actual tilt angle of the test piece corresponding to the tilt angle and the position on the image of the test piece, and the tilt angle and the position on the image of the test piece It can also be data of the corresponding actual tilt angle of the test piece.

It is preferable that the calculation means calculates the bending angle of the work by interpolation calculation of the data stored in the storage means. By doing this,
The bending angle of the work can be accurately determined.

The light projecting means and the image pickup means can be arranged on at least one side of a bending line of the work,
The detection accuracy can be further improved by disposing one set on each side of the bending line.

Here, the light projecting means may be one that forms a linear projected image on the surface of the work by projecting slit light or a plurality of spot lights in series.

Further, in the straight line extracting device used in the bending angle detecting device having the first characteristic, the brightness value of each image forming the multi-valued image is detected by the brightness value detecting means, and the brightness value of each image is detected. A representative pixel related to the optical axis of the bright area of the multi-valued image is calculated along the predetermined coordinate axis of the screen coordinate system from the distribution of, and this calculation is performed along another coordinate axis having a predetermined distance from the coordinate axis. The plurality of representative pixels are repeatedly calculated. Then, a representative straight line of the bright area is calculated from the plurality of representative pixels obtained in this way. In this way, since the original multi-valued image is processed without performing the binarization process, it is possible to accurately extract the representative straight line without being affected by the fluctuation of the optimum threshold value.

In the present invention, further, if noise eliminating means for eliminating noise in the multi-valued image is provided before the luminance value detecting means detects the luminance value of each pixel, the extraction accuracy of the representative line Can be further improved.

Here, the noise elimination means eliminates the noise by subtracting the luminance value of each pixel before and after the formation of the multi-valued image, and makes the luminance value below a predetermined threshold value zero. It is preferable to employ the one that eliminates the noise, or the one that eliminates the noise by setting the luminance value of the isolated pixel in which the luminance value of the adjacent pixel is zero to zero.

Further, as the representative pixel calculation means, the pixel having the largest brightness value is used as a representative pixel along a predetermined coordinate axis, and the distribution centroid of the brightness values is calculated from the distribution of the brightness values of each pixel along the predetermined coordinate axis. The distribution center of gravity is used as the representative pixel, or the half value width of the brightness values is calculated from the distribution of the brightness values of each pixel along a predetermined coordinate axis, and the center value of the half value width is calculated. There are things such as pixels.

Further, as the representative straight line calculating means,
There is one in which a representative straight line is calculated by calculating an approximate straight line from the plurality of representative pixels by the method of least squares. In this case, the approximate straight line is given a predetermined width to obtain a predetermined straight line region, the pixels most distant from the straight line region are deleted, and the approximate straight line is again calculated based on the remaining pixels. It is preferable to calculate the representative straight line by repeating the process until the pixel of

Further, in the straight line extracting device used in the bending angle detecting device having the second feature, the light projecting means projects light at a predetermined light projecting angle onto the surfaces of the work and the lower die, and linearly projects the light. An optical image is formed, the linear projected image is captured by the image capturing means, and the captured image is binarized and thinned by the point arraying means to be represented as a set of point sequences in units of one pixel. To be done. Then, a linear component related to the image of the work connected to the linear component related to the image of the lower mold is extracted from the point sequence thus obtained, and linear projection of the work on the captured image is performed based on the linear component. The tilt angle and position of the image are detected. In this way, it is possible to extract only the necessary straight lines even when the work already bent and the part other than the work are captured as an image, improving the accuracy of bending angle measurement in actual bending and speeding up the processing. Can be achieved.

It is preferable that the point sequence forming means erases points at a predetermined interval and displays the image as a set of the points based on the remaining points.

Further, it is preferable that the straight line component extracting means determines a straight line which is applied to a lower end of an image pickup screen by the image pickup means as a straight line component relating to the image of the lower mold. In this case, a straight line connecting the first point at the lower end of the imaging screen and the second point adjacent to the first point is obtained,
A calculation for obtaining a predetermined straight line area by giving a predetermined width to this straight line, and when the third point adjacent to the second point is included in this straight line area, including the third point to obtain a straight line again When a point that does not fall within the linear range obtained in this way appears, the point up to that point is determined as one line segment so that the linear component related to the image of the work is extracted. It is preferable that the line segment is deleted as an unnecessary portion when the line segment is generated only by two point sequences.

The light projecting means and the image pickup means can be arranged on at least one side of a bending line of the work,
The detection accuracy can be further improved by disposing one set on each side of the bending line.

Here, the light projecting means may be one that forms a linear projected image on the surface of the work by projecting slit light or a plurality of spot lights in series.

Further, in the bending angle detection position setting device according to the present invention, the simulation information calculating means calculates the simulation information relating to the bending state of the work for each bending step from the bending processing conditions of the work, and the simulation information is used as the simulation information. Based on the angle-detectable-process calculating means, a bending process in which the bending angle of the workpiece can be detected by the bending-angle detecting means is calculated. In this way, the position where the bending angle of the work can be detected can be set smoothly, and by extension, highly accurate bending can be realized.

In this case, the position detected by the bending angle detecting means is further specified for the bending step capable of detecting the bending angle calculated by the angle detectable step calculating means, and the instructed detection position is set for each bending step. If the detection pattern storage means for storing the detection pattern is provided, the instructed speed of the detection position for the repetitive work or the similar work can be improved, and the setting time of the detectable position can be shortened.

It is preferable that the simulation information includes a cross-sectional shape of each bending step of the work and a pre-processed shape of the work. In this case, the pre-processed shape includes holes and notches formed on the surface of the work. And it is preferable to include irregularities.

Other objects of the present invention will become apparent from the detailed description given below. However, while the detailed description and specific examples describe the most preferred embodiments, various modifications and variations within the spirit and scope of the invention will be apparent to those skilled in the art from the detailed description, and therefore, specific examples It is only mentioned as.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of a bending angle detecting device, a straight line extracting device used for the same, and a bending angle detecting position setting device according to the present invention will be described with reference to the drawings.

[1] Bending Angle Detection Device FIG. 1 is a side view of the main parts of a press brake according to an embodiment of the present invention. Press brake 1 of this embodiment
Is a lower die (die) 3 supported by the gantry 2 and an upper die attached to a lower portion of a ram 4 which is provided above the lower die 3 so as to be vertically movable. (Punch) 5, a work W made of a metal plate is inserted between the upper die 5 and the lower die 3, and the ram 4 is placed with the work W placed on the lower die 3. Lower the work W
The work W is bent by sandwiching between the upper mold 5 and the lower mold 3.

A bracket 6 is supported on the front portion (man side) of the gantry 2, and a work W is attached to the bracket 6.
A slit-shaped light source 7 for projecting a linear light projection image on the bent outer surface Wa, and C for capturing a linear light projection image by the light source 7.
An angle measurement unit 9 including a CD camera 8 is provided. The angle measuring unit 9 may be provided at the rear part (machine side) of the gantry 2 instead of being provided at the front part of the gantry 2, or both at the front part and the rear part of the gantry 2.

Also, as shown in FIG.
The image captured by the camera 8 is displayed on the monitor television 11 via the calculation unit 10 and stored in the storage unit 12 as image data. This image data is calculated by the calculation unit 10 in consideration of table data of a later-described calibration table which is input from the input unit 13 and stored in the storage unit 12, and the bending angle of the work W is obtained by this calculation. The bending angle obtained by this calculation is given to the ram control device 14, and the ram control device 1
The bottom dead center of the ram 4 is controlled by 4 and the work W is bent at a desired angle.

By the way, as shown in FIG. 3, when the CCD camera 8 captures an image of a linearly projected light U, which is generally formed by projecting the slit light L to the bent outer surface Wa of the work W, this image is obtained. Linearly projected image U ′ on the captured image
The projection image angle θ ′, the projection angle α of the slit light, and the work angle θ have the following relationship in the same way as the above-mentioned expression (d) when considered in the plane projection. tan θ ′ = tan α · tan θ ··· (1)

Since the influence of the angle of view of the lens is not taken into consideration in the equation (1), the linear projection image U ′ displayed on the monitor television 11 is specified as a straight line by image processing in this embodiment. The relationship between the inclination angle θ ′ of the straight line on the screen and the work angle θ is calibrated using the data relating to the position of the straight line as a parameter. Here, the data relating to the position of this straight line is, for example, as shown in FIG.
Draw a line of Y / 2 (where Y is the number of pixels in the y-axis direction),
The linear projection image U ′ is given by the x coordinate of the intersection with the straight line (for example, ax + by + c = 0).

Next, a specific method of this calibration will be described. 5 and 6 are respectively a front view and a plan view of the calibration device used in this embodiment. As shown, in this calibration device, the platen 15
A rail 16 for optical equipment is provided on the rail 16.
An optical unit 19 including a CCD camera 17 and a laser oscillator 18 is movably mounted on the upper part, and a calibration block 20 as a test piece having a known angle is also spaced apart from the optical unit 19 by a predetermined distance. It is movably mounted. Further, the position of the optical unit 19 and the calibration block 20 can be adjusted in the vertical direction.

In the calibration apparatus having such a configuration, the laser beam from the laser oscillator 18 is projected onto the calibration block 20 while the calibration block 20 is held at the predetermined position and the predetermined angle β, and the calibration block 20 is exposed. The projected image of is captured by the CCD camera 17. Then, the inclination angle θ ′ of the projected image on the screen and the position x (see FIG. 4) are calculated to calculate the correction amount δ of the work angle θ. Next, the calibration block 20 is sequentially moved in the z direction (FIGS. 5 and 6) to similarly calculate the correction amount δ, and the calibration block 20 is sequentially changed to one having a different block angle, and the correction amount δ is also changed. Is calculated, and a calibration table is created using the large number of data thus obtained.

Next, the procedure for creating this calibration table is shown in FIG.
This will be described with reference to the flowchart shown in FIG. Here, the angle measurement range, in other words, the angle range to be calibrated is set to β = 60 ° to 120 °. S1 to S6 The angle β of the calibration block 20 is first set to 60 °, the calibration block 20 of this angle β is set, and then the calibration block 20 is moved (retracted) until the image of the laser beam (beam) reaches the left end of the screen. Let Then, the tilt angle θ ′ of the projected image on the screen corresponding to the block angle β and the position x are calculated by image processing, and the correction amount δ corresponding to the tilt angle θ ′ and the position x thus obtained is Formula δ = β-t
The calculated tilt angle θ ′, position x, and correction amount δ calculated by an ⁻¹ (tan α · tan θ ′) are stored and held in the storage unit 12 (see FIG. 2). S7 to S8 The calibration block 20 is moved forward by 2 mm, and when the beam image does not reach the right end of the screen even by this movement, the processes of steps S4 to S7 are repeated at the calibration block position after this movement. It should be noted that the measurement depth range of the calibration block 20 is about 40 mm, and sufficient measurement accuracy can be ensured by collecting data on about 20 points in this range. Therefore, the movement pitch of the calibration block 20 is set to 2 mm. There is. S9 to S11 When the beam image reaches the right end of the screen due to the movement of the calibration block 20, the block angle β of the calibration block 20 is set to the preset maximum angle (120
Angle), that is, when it is not the last calibration block, the block angle β is set to a predetermined angle (3 °).
Only, and the processing from step S2 onward by the next calibration block is repeated, and when the final calibration block is reached, the data string (θ ′, x,
A calibration table is created in the form of an approximate curved surface or an approximate linear expression obtained from the rearrangement of δ) or the data string. The block angle β is β = 60 ° to 120 °
By performing calibration in the range of 3 ° to 5 °,
It has been confirmed that a measurement accuracy of about 0.1 ° can be secured.

An example of the calibration table created in this way is shown in FIG. By using this calibration table, the correction amount δ of the work angle θ can be obtained from the tilt angle θ ′ of the projected image on the screen and the position x, and the correction amount δ is obtained by the above-mentioned equation (1). The final work angle θ is obtained by adding the work angle θ. In addition, in FIG.
The number of data points in the direction is z of the calibration block 20 in FIG.
The number of data points in the θ ′ direction corresponds to the number of calibration blocks 20 having different block angles β, corresponding to the movement pitch in the direction. Then, the data obtained as the calibration block 20 moves in the z direction moves in the direction of arrow P in FIG. 8, and the data obtained as the block angle β increases moves in the direction of arrow Q in FIG. Here, it is necessary to select the number of data points according to the required accuracy.

The above-mentioned correction amount δ is actually obtained by referring to the data of the calibration table from the tilt angle θ ′ and the position x of the projected image obtained by the image processing method, and then using the mathematical interpolation method. It is calculated. Next, a method using a piecewise polynomial will be described as an example of the interpolation method. This method
As shown in FIG. 9, it is a method of approximating a curved surface by a linear expression of a plane with three points that are close to an arbitrary curved surface of three variables (θ ′, x, δ) as shown in FIG. That is, first, the data point (θ ₀ ', x ₀ ) on the θ'-x plane.
Table data (θ ₁ ', x ₁ , δ ₁ ) surrounding
(Θ ₂ ', x ₂ , δ ₂ ) and (θ ₃ ', x ₃ , δ ₃ ) are extracted, and then the plane aθ '+ bx determined by these three points is extracted.
Calculate + cδ + d = 0. And this plane aθ '+
The correction amount δ ₀ obtained from bx + cδ + d = 0 is obtained from the following equation. δ ₀ =-(aθ ₀ '+ bx ₀ + d) / c

By using such an interpolation method, the curved surface can be represented by a large number of first-order polynomials, and the interpolation calculation becomes easy. In addition, it goes without saying that this interpolation method is only an example, and other interpolation methods may be used.

Next, the correction amount δ is calculated by such interpolation.
Fig. 10 shows the procedure for measuring the work angle with consideration of the appearance.
This will be described with reference to the flowchart of FIG. T1 to T3 Tilt angle θ formed by the projected image on the screen₀And place
Setting x₀And are calculated by image processing. Next, θ'-x-
Call the calibration table consisting of the three-dimensional data sequence of δ,
On the θ′-x plane of this called calibration table, the points
(Θ₀’, X₀) 3 points on the closest table surrounding
(Θ₁’, X₁, Δ₁), (Θ₂’, X₂, Δ₂),
(Θ₃’, X₃, Δ₃) Is extracted. T4 to T6 3 extracted points (θ₁’, X₁, Δ₁),
(Θ₂’, X₂, Δ₂), (Θ₃’, X₃, Δ₃) Through
Plane equation aθ ′ + bx + cδ + d = 0 is calculated, and then
In the calculated plane expression aθ ′ + bx + cδ + d = 0
θ '= θ₀′, X = x ₀Substituting₀Calculate
It Then, the equation θ = tan^-1(Tan α · tan θ ′)
+ Δ₀(However, α: Beam projection angle) Workpiece angle θ
Is calculated, and the calculated work angle θ is set to the ram control device 14
(See FIG. 2).

In this embodiment, the correction amount δ is calculated from the calibration table from the inclination angle θ ′ of the linear projection image on the image and the position x, and the work angle is calculated based on the correction amount δ thus calculated. Although the method of calculating θ has been described, a data table capable of directly calculating the work angle θ from the tilt angle θ ′ and the position x is created, and the work angle θ is obtained by referring to the data in this data table. You may do it.

In the present embodiment, the calibration table is shown in FIG.
As described above, the calibration table is composed of a three-dimensional point coordinate group, but this calibration table is also composed of a three-dimensional straight line group obtained from the point coordinate group by an approximation method such as the least square method. It can be expressed in various forms such as an object or an object composed of a three-dimensional curved surface. However,
As described above, the one calibrated with the three-dimensional straight line group and the three-dimensional curved surface has an advantage that the calculation time can be shortened, but on the other hand, the accuracy is deteriorated when the uncertain factors such as the variation of the image receiving element and the lens distortion are large. There are drawbacks.

In this embodiment, the linear projection image is obtained by the slit light, but a plurality of spot lights in series are used instead of the slit light, and the projected spot light of each spot light is used. Obtain an approximate curve passing through the center by calculation,
It is also possible to obtain the projection image angle.

[2] Representative straight line extraction device for extracting a representative straight line from the projected image Next, in the bending angle detection device described above, the tilt angle θ ₀ 'formed by the projected image on the screen and the position x ₀ are calculated. In doing so (see step T1 in FIG. 10), a concrete example of the representative straight line extracting device for extracting the representative straight line from the projected image by image processing will be described.

As shown in FIG. 11, the above-described linear projection image is captured as it is as a multi-valued image through the image input unit 22 in the representative straight line extracting device 21 of this embodiment. The multi-valued image thus captured is, for example, 420 × 510 in width.
Each pixel has a luminance value of 256 (0 to 255) gradation.

The representative straight line extracting device 21 includes a noise erasing section 23 for erasing noise in the multi-valued image captured via the image input section 22, and a multi-valued image in which noise is eliminated by the noise erasing section 23. A brightness value detection unit 24 for detecting the brightness value of each pixel, and a representative pixel calculation for calculating a representative pixel related to the optical axis of the bright area from the distribution of the brightness value of each pixel detected by the brightness value detection unit 24. A unit 25 and a representative straight line calculation unit 26 that calculates a representative straight line from a plurality of representative pixels calculated by the representative pixel calculation unit 25 using a mathematical approximation method such as the least square method.

In the representative straight line extracting device 21 having such a structure, a multi-valued image having a straight bright portion area a as shown in FIG. Then, after the noise in the multi-valued image is erased by the noise elimination unit 23, as shown in FIG. 12B, in the screen coordinate system (xy) of the multi-valued image, The brightness value of each pixel along one pixel band b in the x-axis direction is detected by the brightness value detection unit 24, and the representative pixel c related to the optical axis of the bright area a is detected from the distribution of the brightness values thus detected.
Is calculated in the representative pixel calculator 25. Next, as shown in FIG. 12C, the above-described calculation of the representative pixel is performed on other pixel bands b ′, b ″ ... In parallel with the pixel band b (which may not be parallel). .. are repeatedly performed, and representative pixels c ′, c ″ ... Are extracted as a dot sequence in a pixel unit on the screen. Then, from the point sequence of the representative pixels c ′, c ″ ... Extracted in this way, a representative straight line as shown in FIG. 12D is obtained by a mathematical approximation method such as the least square method. (Approximate straight line) d is obtained.

In order to improve the extraction accuracy of the representative straight line thus obtained, as shown in FIG. 12 (e), the approximate straight line d obtained as described above has a predetermined width (for example, 1 pixel). ) Is added to set the representative linear area e,
The point c _e farthest from the representative straight line area e is deleted. Next, as shown in FIG. 12F, the approximate straight line d'is obtained again based on the remaining representative pixels, and the representative straight line area e'is set again in the same manner as described above. Then, the above-described calculation procedure is repeated until all the representative pixels fall within the representative straight line area (until they converge), thereby finally determining the representative straight line.

Next, the procedure for extracting the representative straight lines shown in FIGS. 12A to 12D will be described more specifically with reference to the flowchart of FIG. U1 to U6 The light source for projecting the linearly projected image on the work is turned off, the 256-gradation image is input to the image memory (M1), and then the light source is turned on to display the 256-gradation image on the image memory (M2). ). Then, the two memories M1,
Subtraction (M3 = M2-M1) is performed between the images input to M2, and the light source is turned off again. An image to be processed is captured by these processes, and noise (luminance value of an unnecessary portion) on the screen is erased by subtraction processing between the images before and after the beam from the light source is projected. U7 to U10 A number i representing the number of optical axis center coordinates is set to 0, an initial value (y ₀ ) of the scanning line y _i is set to 0, and then an image of 256 gradations on the image memory (M3) is set. Regarding the data, the luminance distribution (X, d on the scanning line y = y _i
X) is taken out. Here, dX represents the brightness value (0 to 255) at the position x = X, and X satisfies 0 <X <X _max (where X _max represents the number of pixels in the x-axis direction of the screen). I shall. Next, in order to obtain the distribution centroid of the luminance distribution, the sum N = ΣdX of the luminance values dX is obtained, and the sum S of the products of the coordinate X and the luminance value dX corresponding to the coordinate X is obtained.
= Σ (dX · X) is calculated. Then, the calculated N, S
From each value of the optical axis position x _i at the scanning line y = y _i , x _i =
Calculate by N / S. FIG. 14 shows an explanatory view showing the concept of obtaining the optical axis position from the distribution center of gravity of the luminance distribution (shown by a chain line). The method using this average value is
This is effective, for example, when the brightness value distribution does not become a normal distribution due to color unevenness on the surface of the work. When U11 to U13 y _i have not reached y _max (the number of pixels in the y-axis direction of the screen), the number i is incremented by 1 and the scanning line y _i is divided by the scanning interval p (pitch) in the y-axis direction. (Y _i = y ₀ + ip) and the processes from step U8 onward are repeated, and when y _i reaches y _max , the least squares method is calculated from the obtained plurality of optical axis center coordinates (x _i , y _i ). Representative straight line (approximate straight line) ax + by + c
= 0 is obtained.

In the present embodiment, the description has been given of the case where the noise elimination is performed by the subtraction processing between the images before and after the beam projection, but as another means, a predetermined threshold value is set for the luminance value and There are a method of eliminating noise by setting the luminance value below the threshold value to zero, a method of eliminating noise by setting the luminance value of an isolated pixel in which the luminance value of an adjacent pixel is zero, and the like. Can also be used.

Further, in the present embodiment, in calculating the representative pixel, the distribution centroid of the brightness values of the pixels along the predetermined coordinate axis is obtained from the distribution of the brightness values of the respective pixels. As a method of setting the pixel having the largest luminance value as the representative pixel (see FIG. 15), the half value width g of the luminance values is calculated from the distribution of the luminance values of each pixel along a predetermined coordinate axis, and the center value of the half value width g is calculated. Is obtained, and this central value is used as a representative pixel (see FIG. 16).
The method (1) is effective when there is no color unevenness on the surface of the work and the distribution of the luminance values is a normal distribution.The method (2) is similar to the method of obtaining the distribution centroid described above. It is effective when it does not.

Next, the control flow for improving the accuracy at the time of extracting the representative straight line shown in FIGS. 12 (e) and 12 (f) will be described more specifically with reference to the flowchart of FIG. V1 to V2 representative straight line width (for example, width
= 1 pixel), and the representative straight line (approximation straight line) ax + by + c from the k optical axis center coordinates (x _i , y _i ) (where 0 ≦ i ≦ k) representing the optical axis position on the screen by the least square method. =
Ask for 0. V3 to V6 The number i representing the number of optical axis center coordinates is set to 0, and the distance L _i between the point (x _i , y _i ) and the straight line ax + by + c = 0 is calculated. Then, when i has not reached k, i is incremented by 1 and the distance L _i is sequentially calculated. The distance L _j at the point (x _j , y _j ) where the distance between the optical axis center coordinate and the approximate straight line becomes maximum when V7 to V11 i reaches k is referred to. If the distance L _j is not within the representative straight line width, the coordinate data (x _j , y _j ) is deleted to remove points that are not within the representative straight line width, and k is only 1. Subtracting and returning to step V2, all points (x _j , y _j ) are in the representative linear area wid
If it is within th, the representative straight line (ax + by +
c = 0) is determined.

When the representative straight line extracted by using the representative straight line extracting device 21 according to the present embodiment and the representative straight line extracted by the binarization process are compared in terms of angles on the screen, as shown in FIG. In addition, it was confirmed that the variation in the detection value of the bending angle in this example was small and the detection accuracy was improved.

[3] Straight Line Extracting Device for Extracting Only Required Straight Lines on Image Next, in the bending angle detecting device described above, the tilt angle θ ₀ ′ and the position x ₀ formed by the projected image on the screen are determined. A specific example of a straight line extraction device that extracts only the straight lines required on an image when calculating a work (see step T1 in FIG. 10) and handling a work having a plurality of bending points will be described.

In the bending angle detecting device of this embodiment,
As shown in FIG. 19, the slit light emitted from the light source 7 causes the bending outer surface Wa of the work W and the lower die 3 to be bent.
The light source 7 is arranged so as to hang on a part of
The CD camera 8 is arranged so that the lower mold 3 is imaged in the corner area of the visual field. FIG. 20 shows a captured image when the workpiece W and the lower mold 3 shown in FIG. 19 are captured.
In FIG. 20, 1 is an image of the lower mold 3, n is an image of the already bent portion of the tip of the work W,
These l and n are images that are not directly related to the detection of the bending angle of the work W. The present embodiment proposes a method of extracting only the straight line (the portion m in the example of FIG. 20) necessary for detecting the bending angle in the captured image.

In the straight line extracting apparatus of this embodiment, required straight lines are extracted as follows. That is, C
The image captured by the CD camera 8 is binarized by an appropriate threshold value by using a known image processing technique, and is thinned to have a width of 1 pixel. It is expressed as a set of points (x, y) in units of pixels. Then, from the obtained point sequence image, as shown in FIG. 21A, a straight line s is drawn between the point q at the lower end of the screen and the point r adjacent to the point q, When a predetermined width (for example, one pixel width) t (see FIG. 21B) is given, if the next point u adjacent to the point r falls within the width t, a straight line including the point u is newly provided. If v is redrawn and the next point u does not fall within the width t, the point up to the previous point r is determined as one line segment. By repeating such an operation, a figure consisting of several straight lines can be extracted (see FIG. 21).
(See (c)), the target straight line portion can be extracted by taking out the next straight line w connected to the straight line v that hangs on the lower end of the screen. In the procedure of determining the line segment described above, when the obtained line segment is generated only by the point sequence of two points, it is preferable to delete the line segment as unnecessary.

Next, the straight line extracting procedure shown in FIGS. 21 (a) to 21 (c) will be described more specifically with reference to the flowchart of FIG. Image processing is performed on the beam image captured as the W1 to W3 images, and this image is represented by n coordinate values (x _i , y _i ) (where 0 ≦ i ≦ n) as a set of points in units of one pixel. Next, i = n−1 is set to start from the lowest point on the screen, and the coordinate value (x _i , y _i ) of the start point is set.
And a coordinate value (x _i-1 , y _{i- 1} ) adjacent to the point are calculated by the least squares method, which is a linear expression ax + by + c = 0 that passes through two points. W4 to W8 The number k is set to 2, and the coordinate value (x _ik , y _ik ) of the point (point located in the direction away from the lower edge of the screen) immediately before the point adjacent to the start point is expressed by the above linear equation. The distance l _k from ax + by + c = 0 is calculated. Then, the calculated distance l _k has a preset width W (2
If it is within a pixel (preferably in pixels), the point (x _i , y
For all (k + 1) points from ( _i ) to the point (x _ik , y _ik ), the linear equation ax +
By + c = 0 is calculated, the number k is incremented by 1, and the process returns to step W5. W9 to W10 points (x _ik , y _ik ) are linear expressions ax + b
if the y + c = 0 exceeds the set width W, k of the point (x _i, y _i) from the point _{(x i-k + 1,} y i-k + 1)
It is determined that these points are included in the obtained straight line ax + by + c = 0, and points (x _i , y _i ) to points (x _{i-k + 1} , y _{i-k + 1} )
The length L of the straight line given by is calculated by the following equation. _{L = ((x i-k} + 1 -x i) 2 + (y i-k + 1 -y i) 2)
^1/2 W11 to W15 The obtained length L is a predetermined value H set for judging the length of a straight line (this predetermined value H is set to, for example, 1/2 of the screen, that is, 250 pixels or more. Is preferable.), The next processing is performed. When i−k + 1> 0, in other words, when there is still a point to be extracted, i = i−k is set to start from the next point, and the process returns to step W3. When i−k + 1 ≦ 0, in other words, when there is no point to be extracted, it is judged as an error and the flow is ended. On the other hand, when the length L exceeds the predetermined value H, it is determined that the obtained linear expression ax + by + c = 0 is a point to be extracted on the work, and the inclination θ of the straight line on the screen is determined based on this straight line. 'And the position x are calculated by the following equations, respectively, and this flow is finished. θ ′ = tan ⁻¹ (a / b) x = − (b · Y / 2 + c) / a) where Y represents the number of pixels in the y direction of the screen.

In the straight line extracting apparatus of this embodiment, when representing a thinned continuous line of one pixel width as a set of a large number of points, the straight lines are separated at predetermined intervals according to the accuracy required for the purpose of shortening the calculation time. You can also delete points.

[4] Bending Angle Detection Position Setting Device Next, the work W is detected using the bending angle detection device as described above.
A specific example of the bending angle detection position setting device for setting the bending angle detection position when detecting the bending angle will be described.

As shown in FIG. 23, in the present embodiment, a simulation relating to the bending state of the work W in each bending step from the machining conditions such as machine / equipment conditions, work shape and die shape. A simulation information calculation unit 27 that calculates information (simulation information for each bending process, for example, a sash is shown in FIG. 24) is provided, and the information from this simulation information calculation unit 27 is used to set the bending angle detection position. It is adapted to be input to the device 28. Here, the machine / equipment conditions are machine specifications (shapes of table and ram) and angle detection device specifications (number of units, number of moving axes / distances, effective detection range). The conditions are corners, bending length, leg length, material, notch shape at the time of blanking, concavo-convex shape, etc., and the die shape is V width, die shape, punch shape, die holder shape, etc.

In this bending angle detection position setting device 28, the cross-sectional shape and pre-processed shape (pierce, emboss, etc.) of the work W are detected by the detectable position analysis section 29 based on the input information from the simulation information calculation section 27. The bending angle detectable position of the work W is analyzed separately.
Further, based on the analysis result, the detection position designating unit 30 designates specific detection positions such as the longitudinal position and the vertical position of the bending angle detecting device, and further the detection designated by the detection position designating unit 30 is realized. In order to do so, the detection position setting unit 31 calculates the control data of the bending angle detection device. And
The bending angle detection device is controlled by the detection position control device 32 based on the control data calculated by the detection position setting part 31. Further, in order to reduce the instruction time of the repetitive work and the similar work, the detection pattern of the bending angle detection device instructed by the detection position instructing unit 30 is registered and updated in the storage unit 33 so that it can be used. . The detection position setting unit 31 also sets the position of the bending angle detection device when there are a plurality of bending angle detection devices and when there is a progressive machining. Further, the detection position control device 32 controls a bending angle detection device unitized with a light source and a CCD camera so as to move in the longitudinal direction of the machine body, and also the projection angle of the light source and the reception angle of the CCD camera. Control to change.

The bendable angle detectable position in the detectable position analyzing unit 29 is analyzed as follows.

(A) Detectable position analysis based on the sectional shape of the work W (see FIG. 25) In order to accurately detect the bending angle of the work W, the slit light L projected from the light source onto the work W is the work. W
It is necessary to judge whether or not a predetermined width is applied in the same plane. This determination is performed by the procedure shown below. In addition, in FIG. 25 explaining this determination procedure, (b) shows a partially enlarged view of (a). Line segments GI, JK, G'I ', J'K' offset by a minute distance ε around the work W are defined, and line segments EK, E'K 'outside the slit light L are defined. These line segments GI, JK, G'I ', J'K', E
Each side of K, E'K 'and work W 0-1, 1-2, 2-
Check for intersections with 3, 3-4, 4-5. It is checked whether the point 0 or the point 5, which is the end portion of the work W, exists in the area surrounded by GIJK or G'I'J'K '. With the above checks, it is determined that the bending angle can be detected if there is no intersection between the work W and the line segment and there is no work end in the area.

(B) Detectable position analysis based on the pre-processed shape of the work W (see FIG. 26) If there is a hole, a notch, an unevenness or the like in the work portion where the slit light L is projected, the bending angle cannot be detected well. Therefore, it is necessary to determine whether or not the bending angle can be detected by determining whether or not there are such holes. This determination is performed by the procedure shown below. In addition, in FIG. 26 for explaining this determination procedure, FIG. 26B is a diagram showing the work W in a developed state. The work W is unfolded, and the slit light L is expanded in the unfolded state in consideration of the bending margin expansion margin, the projection position of the slit light L, and the like.
Find the range hit. The pre-processed part is divided into individual units such as hole A, hole B, hole C, and so on. The maximum value Y _nmax and the minimum value Y _nmin of the Y-axis are obtained for each pre-processed portion, and the positional relationship between these maximum values Y _nmax and minimum value Y _nmin with respect to the straight lines Ya and Yb showing the projection range of the slit light L is shown. It is checked, and the presence or absence of influence on the detection is determined as follows. (i) Y _nmax , Y _nmin > Ya or Y _nmax , Y _nmin <Y
In the case of b, it is determined that there is no influence, and when these conditions are not satisfied, it is determined that there is influence. (ii) For the affected unit, the undetectable range is determined from the shape (circle, corner, etc.) of each unit, the position of these units, and the positional relationship with respect to the straight lines Ya and Yb.

Next, the procedure for setting the bending angle detecting device by the bending angle detecting position setting device 28 of this embodiment will be described with reference to the flowchart of FIG. X1 to X3 Enter machine / equipment conditions, work shape, mold shape. X4 to X5 The bending order analysis of the work W is performed to calculate the simulation information related to the bending state of each bending step, and the detectable position analysis unit 29 determines the cross-sectional shape and the pre-processing shape of the work W from this simulation information. The position where the bending angle of the workpiece W can be detected is analyzed separately, and the analysis result is displayed. Note that a plurality of solutions are output in the bending order analysis. X6 to X9 The quality of the obtained analysis result is determined, and if the analysis result is not good, the process returns to step X4 to perform the analysis again. On the other hand, if the result of the quality determination is good, the detection position instructing unit 30 indicates a specific detection position such as the longitudinal position or the vertical position of the bending angle detection device from the analysis result, and the bending angle detection device 30 Set the control data of. In this case, a pre-registered detection pattern (for example, a pattern indicating an eccentric position from the work center) is used, and a new detection pattern (updated data) is registered. Next, if the setting of all processes is not completed, the process is changed and the detection position is instructed and set again in step X7. If the setting of all processes is completed, the flow is ended.

In the flow chart shown in FIG. 27, it is preferable to consider not only the above-described analysis of the detectable position but also the ease of image processing in the bending angle detecting device when the bending order is analyzed in step X4.

Bending angle detection position setting device 28 of this embodiment
In the above, it is preferable to retract the bending angle detecting device to a position that does not interfere with the processing after detecting the bending angle.

Further, when the bending angle detecting device is moved to a predetermined position, it is preferable that the detection data is automatically calibrated along with the movement by using, for example, a calibration table.

Bending angle detection position setting device 28 of this embodiment
In the above, we explained that the detectable position of the bending angle is obtained and the detected position is indicated based on the obtained detectable position. On the contrary, it is automatically detected at the specified detected position. An embodiment is also possible in which the determination is made and the detection position is determined.

As described above, it is obvious that the present invention can be modified in various ways. Such modifications are within the spirit and scope of the invention and all such variations and modifications apparent to those skilled in the art are intended to be within the scope of the following claims.

[0081]

According to the bending angle detecting apparatus of the present invention, complicated calculation can be performed without measuring the distance between the work and the image pickup means or the direction angle of the beam from the light projecting means. Without performing it, the bending angle of the workpiece can be detected with high accuracy by calibrating indeterminate factors such as lens distortion and image receiving element variation with a simple mechanism.

Further, according to the straight line extraction device used in the bending angle detection device having the first feature of the present invention, the representative pixel of the bright area of the multi-valued image is obtained without performing the binarization process, and Since the representative straight line is extracted from the representative pixel, the accuracy in extracting the straight line can be dramatically improved.

Further, according to the straight line extracting device used in the bending angle detecting device having the second feature of the present invention, the image pickup means is arranged so that the image of the lower mold is shown, and the image of the lower mold is also displayed. Since the connected straight line components are extracted, even if a work that has already been bent or a part other than the work is captured as an image, only the straight line necessary for bending angle detection can be extracted, and the bending angle can be measured. The accuracy of can be improved. Further, if the straight line at the lower end of the screen and the straight line connected to the straight line can be extracted, the subsequent data becomes unnecessary, which can greatly contribute to the reduction of the calculation time.

Further, according to the bending angle detection position setting device of the present invention, it is possible to smoothly set the position where the bending angle of the workpiece can be detected, and thereby it is possible to realize highly accurate bending. Become. Is.

[Brief description of drawings]

FIG. 1 is a side view of a main part of a press brake to which a bending angle detecting device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating an image processing method and a ram control method in the bending angle detection device.

FIG. 3 is a diagram showing a positional relationship between a light source, a work, and a CCD camera in the bending angle detection device.

FIG. 4 is a diagram showing an example of an image in the bending angle detection device.

FIG. 5 is a front view of a calibration device used in the bending angle detection device.

FIG. 6 is a plan view of a calibration device used in the bending angle detection device.

FIG. 7 is a flowchart showing a procedure for creating a calibration table in the bending angle detection device.

FIG. 8 is a diagram showing a calibration table in the bending angle detection device.

FIG. 9 is a diagram for explaining data interpolation of a correction amount of a work angle in the bending angle detection device.

FIG. 10 is a flowchart showing a procedure for measuring a work angle in the bending angle detecting device.

FIG. 11 is a block diagram of a representative straight line extracting apparatus according to an embodiment of the present invention.

FIG. 12 is a diagram illustrating a processing procedure in the representative straight line extraction device.

FIG. 13 is a flowchart showing a processing procedure in the representative straight line extraction device.

FIG. 14 is a diagram showing an example of a representative pixel calculation method in the representative straight line extraction device.

FIG. 15 is a diagram showing another example of a representative pixel calculation method in the representative straight line extraction device.

FIG. 16 is a diagram showing still another example of the representative pixel calculation method in the representative straight line extraction device.

FIG. 17 is a flowchart showing a processing procedure for improving accuracy in the representative straight line extracting device.

FIG. 18 is a diagram showing the detection accuracy of the representative straight line extracting apparatus of the present embodiment in comparison with the conventional example.

FIG. 19 is a diagram showing a device configuration of a straight line extracting device according to an embodiment of the present invention.

FIG. 20 is a diagram showing an example of an image in the straight line extracting device.

FIG. 21 is a diagram illustrating a processing procedure in the straight line extracting device.

FIG. 22 is a flowchart showing a processing procedure in the straight line extracting device.

FIG. 23 is a block diagram showing a configuration of a bending angle detection position setting device.

FIG. 24 is a diagram showing a bending state in each bending step.

FIG. 25 is a diagram for explaining the procedure of the detectable position analysis based on the sectional shape of the work.

FIG. 26 is a diagram illustrating a procedure of a detectable position analysis based on a pre-processed shape of a work.

FIG. 27 is a flowchart showing a setting procedure of the bending angle detecting device by the bending angle detecting position setting device.

FIG. 28 is a diagram illustrating a relationship between a beam direction angle, an angle formed by an image on an image, and a bending angle.

FIG. 29 is a diagram showing an example of a linear projected image.

FIG. 30 is a diagram showing another example of the linear projection image.

[Explanation of symbols]

 1 Press Brake 3 Lower Die 5 Upper Die 8 Light Source (Light Emitting Means) 9 CCD Camera (Imaging Means) 10 Computing Unit (Computing Means) 11 Monitor Television 12 Storage Unit (Storage Means) 20 Calibration Block (Test Pieces) 21 Representative straight line extraction device 22 Image input unit 23 Noise elimination unit 24 Luminance value detection unit 25 Representative pixel calculation unit 26 Representative straight line calculation unit 27 Simulation information calculation unit 28 Bending angle detection position setting device 29 Detectable position analysis unit 30 Detected position instruction unit 31 detection device setting unit 32 detection device control device 33 storage unit W work

Claims (27)

[Claims] 1. A bending angle detection device for detecting a bending angle of a work by image processing, comprising: (a) projecting a linear projection image on a surface of the work by projecting light at a predetermined projection angle. Light means, (b) image pickup means for picking up the surface of the work on which the linear light projection image is formed by the light projection means, (c) the linear light projection on the image picked up by the image pickup means Projection image detection means for detecting the tilt angle and position of the image, (d) Corresponding to the tilt angle and position on the image of the test piece obtained by imaging a test piece having a known tilt angle in advance. Storage means for storing data relating to the actual inclination angle of the test piece, and (e) the storage means based on the inclination angle and position of the linear projection image detected by the projection image detection means. By referring to the stored data A bending angle detection device comprising a calculation means for calculating the bending angle of the workpiece. 2. The data stored in the storage means is data of the correction amount of the actual tilt angle of the test piece corresponding to the tilt angle and position on the image of the test piece. The bending angle detection device described in. 3. The data stored in the storage means is data of the actual tilt angle of the test piece corresponding to the tilt angle and position on the image of the test piece.
The bending angle detection device described in. 4. The bending angle detection device according to claim 1, wherein the calculation means calculates the bending angle of the work by interpolation calculation of the data stored in the storage means. 5. The bending angle detecting device according to claim 1, 2, 3 or 4, wherein the light projecting means and the imaging means are arranged on at least one side of a bending line of the work. 6. The bending angle according to claim 5, wherein the light projecting means forms a linear projected image on the surface of the work by projecting slit light or a plurality of spot lights in series. Detection device. 7. A straight line extracting device for extracting a representative straight line of a bright area from a multi-valued image having a linear bright area, comprising: (a) determining a brightness value of each pixel constituting the multi-valued image. Luminance value detecting means for detecting, (b) A representative pixel relating to the optical axis of the bright area is calculated along a predetermined coordinate axis of the screen coordinate system from the distribution of the luminance value of each pixel detected by the luminance value detecting means. The representative pixel calculating means for calculating a plurality of representative pixels by repeating this calculation along another coordinate axis having a predetermined distance from the coordinate axis, and (c) the plurality of representative pixels calculated by the representative pixel calculating means. A straight line extracting device used in a bending angle detecting device, comprising a representative straight line calculating means for calculating a representative straight line of the bright area. 8. The noise erasing means for erasing noise in the multi-valued image prior to detecting the luminance value of each pixel by the luminance value detecting means is further provided. A straight line extraction device used for the bending angle detection device described. 9. The straight line used in the bending angle detecting device according to claim 8, wherein the noise elimination means eliminates the noise by subtracting the luminance value of each pixel before and after the formation of the multi-valued image. Extractor. 10. The straight line extraction device used in the bending angle detection device according to claim 8, wherein the noise elimination means eliminates the noise by setting a luminance value equal to or less than a predetermined threshold value to zero. 11. The bending angle detection device according to claim 8, wherein the noise elimination means eliminates the noise by reducing the luminance value of an isolated pixel in which the luminance value of an adjacent pixel is zero. Line extraction device used for. 12. The straight line extraction device used in the bending angle detection device according to claim 7, wherein the representative pixel calculation means sets a pixel having the largest luminance value as a representative pixel along a predetermined coordinate axis. 13. The representative pixel calculating means obtains a distribution centroid of luminance values of each pixel along a predetermined coordinate axis, and sets the distribution centroid as a representative pixel. Straight line extraction device used in the bending angle detection device. 14. The representative pixel calculation means obtains a half value width of the luminance values from a distribution of the luminance values of each pixel along a predetermined coordinate axis, obtains a center value of the half value width, and sets the center value as a representative pixel. The straight line extraction device used for the bending angle detection device according to claim 7. 15. The straight line used in the bending angle detecting device according to claim 7, wherein the representative straight line computing means computes a representative straight line by computing an approximate straight line from the plurality of representative pixels by a least square method. Extractor. 16. The representative straight line calculating means obtains a predetermined straight line area by giving the approximate straight line a predetermined width, deletes a pixel farthest from the straight line area, and approximates again based on the remaining pixels. The straight line extracting device used in the bending angle detecting device according to claim 15, wherein the representative straight line is calculated by repeating the calculation for obtaining the straight line until all the pixels fall within the straight line region. 17. (a) A linear projection image is formed on the surfaces of the work and the lower die by projecting the work and a part of the lower die on which the work is placed at a predetermined projection angle. Light projecting means, (b) an image capturing means for capturing an image of the surface of the work and the lower die on which the linear light projected image is formed by the light projecting means, and (c) two images captured by the image capturing means. Point sequence conversion means that is expressed as a set of point sequences in units of one pixel after being binarized and thinned, and (d) the point sequence obtained by the point sequence conversion means is connected to a straight line component relating to the image of the lower mold. A straight line component extracting means for extracting a straight line component relating to the image of the work; and (e) a linear projection of the work on the image picked up by the image pick-up means based on the straight line component extracted by the straight line component extracting means. Projection image detection for detecting the tilt angle and position of the image A straight line extracting device for use in a bending angle detecting device, comprising: 18. The bending angle detecting device according to claim 17, wherein the point sequence forming means erases points at predetermined intervals and displays the image as a set of points based on the remaining points. Straight line extraction device. 19. The straight line component extracting means determines a straight line which is applied to a lower end of an image pickup screen by the image pickup means as a straight line component relating to an image of the lower mold.
A straight line extraction device used in the bending angle detection device according to. 20. The straight line component extracting means includes a first point at a lower end of the imaging screen and a second point adjacent to the first point.
A straight line that connects the point and is obtained, a predetermined width is obtained by giving this straight line a predetermined width, and when a third point adjacent to the second point falls within this straight line, the third line Repeating the calculation to obtain a straight line again including the point, when a point that does not fall within the straight line region obtained in this way appears, the point up to that point is judged as one line segment The straight line extraction device used for the bending angle detection device according to claim 19, which extracts the straight line component. 21. The bending angle detection according to claim 20, wherein the straight line component extracting means deletes the line segment as an unnecessary portion when the line segment is generated only by a sequence of two points. A straight line extraction device used in the device. 22. The straight line extracting device used in the bending angle detecting device according to claim 17, 18, 19, 20 or 21, wherein the light projecting means and the imaging means are arranged on at least one side of a bending line of the work. . 23. The light projecting means forms a linear projected image on the surfaces of the work and the lower die by projecting slit light or a plurality of spot lights in series. A straight line extraction device used for the bending angle detection device described. 24. A bending angle detection position setting device for setting the detection position when detecting the bending angle of a work by the bending angle detection means, comprising: (a) a bending process condition of the work for each bending step of the work. Simulation information calculating means for calculating simulation information relating to a bending state, and (b) an angle for calculating a bending process capable of detecting a bending angle of a workpiece by the bending angle detecting means based on the simulation information calculated by the simulation information calculating means. A bending angle detection position setting device comprising a detectable process calculation means. 25. Further, the position detected by the bending angle detecting means is specified for the bending step capable of detecting the bending angle calculated by the angle detectable step calculating means, and the detected position is bent. 25. The bending angle detection position setting device according to claim 24, further comprising detection pattern storage means for storing a detection pattern for each process. 26. The bending angle detection position setting device according to claim 24 or 25, wherein the simulation information includes a cross-sectional shape of each bending step of the work and a pre-processed shape of the work. 27. The pre-processed shape includes a hole, a notch, and an unevenness formed on the surface of the work.
Bending angle detection position setting device described in.