JPH03259705A - Angle measuring instrument for bending machine - Google Patents

Abstract

PURPOSE:To mount the angle measuring instrument on a bending machine, and to measure the angle of inside part from a work end surface with high accuracy by providing image pickup devices which can find the tilt angles of corresponding surfaces of a work in front of and behind a die, and composing an image of their picked-up images and finding the bending angle of the work. CONSTITUTION:The image pickup devices 9F and 9B are provided on both the front and rear surface sides of the punch 6 and connected to an image processor on the ground. A laser diode 14 which irradiates the top surface of the work bent by the punch 6 and a die 5 with slit plane light and a visual sensor 15 which picks up an image of a linear light beam pattern appearing on the work surface with the plane light are provided in both the devices 9F and 9B. Then the work being bent is measured at an optional position inside its end surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an angle measuring device for a bending machine suitable for measuring the current bending angle of a workpiece during bending.

(Prior Art) Conventionally, for example, when measuring the bending angle of a bent workpiece, it is common to inspect the workpiece by applying an angle measuring jig such as a scorer or protractor having a predetermined angle to the workpiece.

However, these methods have problems in that individual errors of the measurer occur and measurement takes a lot of time. Additionally, with the trend towards factory automation, it has been impossible to automate the inspection process. Furthermore, bending machines perform bending by the relative approach and separation movements of the upper die (punch) and lower die (die), but the angle is measured during bending and the bending process is automatically performed. That is, the moving position of the mold could not be automatically determined so that the final bending angle would be the target bending angle.

Therefore, conventionally, for example, in Japanese Patent Publication No. 63-2687 (press brake plate bending angle detection device), the minimum bending angle of the workpiece is detected by capturing an image of the end face of the workpiece during bending with a visual sensor. We are trying to perform automatic bending.

However, including the above-mentioned Special Publication No. 63-2687,
The conventional method of detecting the bending angle of a workpiece using a visual sensor images the end face of the workpiece and detects the slight bending angle on the end face of the workpiece, which makes it impossible to accurately detect the bending angle. Even if automatic bending is performed using the values, there is a problem in that highly accurate bending cannot be performed and it cannot be put to practical use.

In other words, when it comes to plate-shaped workpieces that are bent, it is common for the end faces to be distorted in the raw material stage, have cracks, or have a tapered cross section. It is difficult to detect the correct bend angle.

In particular, when imaging the end face of a workpiece using a reflective imaging method,
If the workpiece end face of the material is a tapered surface, the reflected light will be uneven, and the image obtained by this reflected light will differ from the actual shape. In particular, when constructing a transmission type imaging device, a projector must be provided for that purpose, which increases the size of the device and makes it difficult to generalize the device.

In addition, in angle detection at the end face of the workpiece, the setting position of the visual sensor is limited to the direction of the end face of the workpiece, so there is also a problem that the frame configuration of the bending machine is limited.

In addition, when detecting the angle at the end face of the workpiece, the workpiece is distorted in an arch shape when viewed from the front side of the bending machine due to the so-called sagging phenomenon, as shown in Figure 1.3, so the detected bending angle is There was a problem that the value was not representative of the bending angle of the workpiece.

Therefore, the present inventors proposed an angle measurement method for measuring the intersection angle of two planes as measurement surfaces of a workpiece bent into a V-shape when viewed from the lateral direction of a bending machine. A single planar light by scanning a light or a linear beam is irradiated, and the linear light ray patterns appearing on each of the two planes are imaged from an imaging direction that is in a fixed relationship with the two planes and the irradiation surface of the planar light. An angle measurement method has been proposed in which an image is captured on plane coordinates and the intersecting angle of the two planes is measured from the angle made with respect to a reference line of a light ray pattern on the plane coordinates.

According to this proposal, by irradiating one planar light onto two planes as the surfaces to be measured, and imaging the light ray pattern appearing on each surface to be measured by this planar light using an imaging device,
From the relationship between the irradiation direction or posture of the planar light and the imaging direction, it is possible to measure the intersection angle of the two planes, that is, the bending angle of the workpiece.

(Problem to be Solved by the Invention) However, in the angle measurement method proposed as described above, in the bending machine, the work is interposed between the molds consisting of a punch and a die, and both molds approach and separate. Since the workpiece is bent by motion, there is a mold at the position where the image is to be taken, making it difficult to mount it on the bending machine.

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art described above, improves the above proposal, can be implemented in a bending machine, and measures the bending angle of a portion inside the end face of a workpiece with high precision during bending. The object of the present invention is to provide an angle measuring device for a bending machine.

[Structure of the Invention] (Means for Solving the Problems) The present invention, which solves the problems described in item 1, involves interposing a plate-shaped workpiece between a mold consisting of a punch and a die, and reducing the relative proximity of the punch and die.・An angle meter 7 of a bending machine that bends the workpiece back and forth with respect to the bending line of the mold by separating the workpiece.
In the 1111 device, corresponding surfaces of the workpiece are set as surfaces to be measured in front and rear of the mold, and planar light by scanning a slit light or a linear beam is irradiated onto the surfaces to be measured, and the surfaces to be measured are An imaging device is provided for imaging a linear light beam pattern appearing on a plane coordinate from an imaging direction that has a fixed relationship with the surface to be measured and the surface irradiated with the planar light, and the plane coordinates imaged by each imaging device are provided. An image processing device is provided for determining the bending angle of the workpiece by synthesizing the inclination angles of each measured surface with respect to each imaging direction determined from the angle made with respect to the reference line of the light beam pattern in step 2. do.

Also, considering a three-dimensional XYZ in which the plane coordinate YZ includes the normal line of one measurement surface to be imaged by one imaging device, the above-mentioned 72
A surface obtained by tilting the surface by an angle β toward the X-axis side is used as the irradiation surface, and the light beam pattern is imaged on the XY plane coordinates from the Z-axis,
The method is characterized in that, assuming that the angle of the imaged light beam pattern with respect to the X-axis is θ, the inclination angle α of the surface to be measured with respect to the Z-axis is determined by α=tant−′ (tanθ·tanβ).

In addition, in this case, by setting β to 45 degrees, α −
It is characterized by θ.

Further, the imaging device is characterized in that it is movable in the left-right direction with respect to the mold.

Further, the imaging device is characterized in that a plurality of imaging devices are provided with respect to the mold at appropriate intervals in the left-right direction, and the imaging devices are appropriately switched and used for a portion to be measured in angle.

Further, a plurality of the imaging devices are provided with respect to the mold at appropriate intervals in the left-right direction, and the measured angle is an average value of angle data measured by the plurality of imaging devices.

(Function) The angle measuring device for the bending machine of the present invention is provided with imaging devices capable of determining the inclination angles of the surfaces corresponding to the front and rear of the mold, and combines the imaging results of both imaging devices to Since the bending angle is determined, it can be mounted on a bending machine, and the angle can be measured inside the end surface of the workpiece being bent.

Furthermore, if the imaging device is movable left and right, an appropriate position can be measured depending on the length of the workpiece.

Furthermore, when a plurality of imaging devices are provided on the left and right, any imaging device can be selected and the angle can be measured at any position. In addition, when taking the average value of the measurement surface using multiple imaging devices installed in the left and right direction, even if the so-called sagging phenomenon occurs, in which the bending angle at the middle part becomes less than the bending angle at the end face part, A suitable bending angle can be obtained.

(Example) The present invention will be explained in detail below.

First, an overview of the folding machine that implements the present invention will be shown.
As shown in the front view in FIG. 2, the bending machine (bender) has a side frame 2 that is C-shaped when viewed from the side, and a lower part that connects the side frame 2 at the lower and upper sides. It comprises a frame 3 and a two-part frame 4.

A die 5 extending in the left-right direction via a die boulder is fixedly disposed at the second portion of the lower frame 3.

Further, a ram that can be raised and lowered up and down is provided along the upper frame 4, and a punch 6 facing the die 5 is connected directly below this ram.

The upper end of the ram is provided with cylinder devices S3/L and syR connected via spherical bearings to both upper ends thereof, and the punch 6 is moved closer to the die 5 by simultaneous operation of both cylinder devices SVL and SYH.・It is designed to make people leave.

The operation of the punch 6, that is, the cylinders SyL, S
The operating state of the YH is determined by detecting a linear scale provided inside the side frame 2 with a rotary encoder provided on the side of the ram, and managing the ram position. The operating axis of the ram is called a depth (D) axis, and the position of the ram is controlled by an electro-hydraulic servo circuit (not shown).

An example of a position control method is to use a pre-created speed pattern to lower the punch 6 at high speed until the tip of the punch 6 approaches the workpiece placed on the die 5, and then the workpiece reaches the bending target. It operates at low speed until it gets close to the corner.
The system then switches to slow-speed operation, temporarily stops at the final bending position determined in consideration of springback of the workpiece, and then rises.

An arm 7 rotatable in a horizontal plane is provided on the left side of the upper frame 4, and a pendant 8 serving as an operation panel is suspended from the lower end of the arm 7.

The operation surface of the pendant 8 is provided with a display and various operation switches. Further, although not shown, for example, an NC operation panel is provided on the left side of the figure.

On the other hand, in the bending machine 1 of this example, an imaging device 9 for angle measurement is provided on the front side and the rear side of the punch 6, and an image processing device 10 placed on the ground, a power line 11, and a signal line 1 are provided.
Connected via 2.

An angle display 13 and appropriate operation keys are arranged on the panel of the image processing device 10. This image processing device 10 is connected to the NC operation panel.

Details of the imaging device 9 are shown in FIG. The imaging devices installed before and after punching are shown as 9P%19B, respectively. Similarly, connect the front and rear wiring 11.12 to 11p, i
Indicated by ln and 12p, 12B.

As shown in the figure, each of the imaging devices 9p and 9n has a laser diode 1 inside thereof that irradiates a slit light as a planar light toward the upper surface of the workpiece to be bent between the two full molds 5.6.
4, and a visual sensor 15 equipped with a CCD area sensor for respectively capturing images of linear light beam patterns appearing on the upper surface of the workpiece by these planar lights.

3 and 4 show a front view and a right side view of the imaging device 9.

In the figure, it is assumed that both visual sensors 15 are arranged on a vertical axis along the punch 6 and image a light beam pattern appearing on the workpiece W directly below them.

The vertical axis is Z (ZF, 'ZB), the bending line direction is X1
Take the front-back direction as the Y-axis. In this case the axes zP, ZB are parallel.

In this state, it is assumed that the slit light SL exists in a plane shape in which the YZ plane is tilted by an angle β in the X-axis direction.

FIG. 5 is an explanatory diagram of a method for mounting an imaging device, modeling the relationship shown in FIG. 4.

In the relationship shown in FIG. 5, if both imaging axes zP and ZB are made to coincide, as shown in FIG. The bending angle is an inclination angle α1 of the planes WF and WB with respect to the Z axis. It can be expressed as the sum of αB.

α=α, +α8...(1) Therefore,
Inclination angle α1. By measuring α8 and finding the sum, the intersection angle α between the two planes can be found.

7(a) is a plan view of FIG. 6, FIG. 7(b) is a front view of FIG. 6, and FIG. 7() is a right side view of FIG. 6.

In the figure, the upper half and lower half of the plan view of FIG. 7(a) can be imaged on each area sensor of the visual sensor 15 of each imaging device 9p, 9n.

Therefore, in the plan view of FIG. 7(a), the angles formed by the light beam pattern PP and the pH X-axis on the front and rear planes are Or and β8, respectively, and the height of each plane in the front view is HF,
HR1 The projection length of each ray pattern PrPB on the X axis is L
When P and LB are used, the following equation holds true for the plane Wr.

As a result, α is tan a F = tan θ, , -tan βFa p
= jan −” (tan θp−janβF).

Similarly, on the plane WB, tx B = jan '-' (tanθ,, -ja
nβF)...(5)...(6)

Therefore, the bending angle α of the workpiece can be determined using equation (1).

When β, -β8=45 degrees, α=θ, +08, so there is no need to perform the calculations of equations (5) and (6).

In the second embodiment, the planar light is composed of the slit light SL, but the planar light can also be obtained by scanning a linear beam on the irradiation surface.

Further, in the above embodiment, a CCD camera is used as the visual sensor 9, but other cameras may be used as long as they can capture two-dimensional images.

Moreover, although the slit light SL from the laser diode 14 is taken as an example of the light emitting device, any light emitting device may be used as long as it can emit planar light. However, since the linearity of planar light affects angle detection accuracy, a light emitter with high linearity such as a laser beam can detect angles with higher accuracy.

FIG. 8 shows an image processing device 1 connected to the visual sensor 9.
FIG. 2 is a block diagram showing the internal configuration of 0.

The image processing device 10 of this example has a CP on the system bus 16.
U17, ROM18, RAM19, output device (Ilo) 20, display ink face 2]-1
The image memory 22 is connected to the image memory 22, and the image memory 22 is provided with a binarization (A/D) circuit 23 for converting the video signal of the visual sensor 9 into a binarized signal.

The display 13 described above is connected to the display interface 21 . The input/output device 20 is connected to an NC device 24 provided in the NC operation panel.

In the above configuration, the image memory 22 includes a visual sensor 9
Images taken at r or 9B, respectively, are obtained, and CP
At U 1.7, the process shown in FIG. 9 is executed to obtain the angles α and αB, and the bending angle α of the workpiece W is measured by the sum of the angles α and αB. Output.

In FIG. 9, in step 901 the angle β (β1.βB
) is input. If not input, the angle β is set in step 902.

Next, in step 903, image data is input, and in step 904, the inclination angle θ1. θ8 is detected, and if it is not detected, the process returns to step 903 via step 508, but if it is detected, the process proceeds to step 906 and (1) to
Calculate the workpiece bending angle α from equation (6), and step 907
and output it.

The NC device 24 inputting the measured bending angle α can perform automatic bending in the same manner as the control method shown in Japanese Patent Publication No. 63-2687.

That is, the NC device 24 manually calculates the current bending angle α, controls the position of the punch 6 so that this angle α becomes the target angle α0, and controls the bending angle after springback to the product accuracy. be able to.

However, the bending angle α measured in this example is not obtained from the end face shape of the workpiece W, but as described above, the two planes W p and W B at the front and back of the workpiece W are measured surfaces, and the bending angle α is obtained from the inner side of the end face. Since it is obtained by imaging the workpiece surface, the measured angle can be treated as the workpiece bending angle, and from a practical standpoint, a different effect from that of the conventional example can be obtained.

FIG. 10 shows an example in which imaging devices 9F' and 9'B are provided before and after the die 5. FIG. 11 is an explanatory diagram modeled as a right side view. wF', wB'' in Figure 11
indicates the front and rear surfaces of the lower surface of the workpiece.

In this case as well, the inclination angle of the lower surface of the workpiece W with respect to the imaging direction can be detected as in the case of FIG.
The bending angle α can be found.

In the model shown in correspondence with FIG. 11, imaging devices are installed at the rear of the punch and at the front of the die, and the bending angle α of the work W is obtained by imaging the rear upper surface WB and the front lower surface WP° of the work W.
It was designed to seek.

In this way, the angle measuring device includes an imaging device 9 that can determine the workpiece inclination angle by imaging the rear and front of the workpiece.
They do not necessarily have to be arranged facing each other on the punch side or the die side.

Also, for convenience of explanation, the imaging device 9 (9'p, 9
s) is shown as being directly fixed to the punch 6 or die 5, but it may be fixed to a holder or frame, or it may be configured to be movable.

As an example of configuring the imaging device 9 to be movable, it can be driven up and down at the time of imaging, or moved in the longitudinal direction of the workpiece W depending on the length of the workpiece W, or a structure that combines both. .

Furthermore, by installing multiple sets of imaging devices along the longitudinal direction of the workpiece and using angle meters at multiple positions, it is possible to measure according to the length of the workpiece and calculate the average value to determine the appropriate bending angle α. can be obtained.

By measuring the bending angle of the workpiece at multiple positions, it is possible to actually measure the sagging phenomenon of the workpiece and optimize the intermediate plate and shim adjustment amounts. Furthermore, when a central cylinder is provided, the amount of adjustment thereof can be made appropriate.

The present invention is not limited to the above-mentioned embodiments, but can be implemented in any appropriate manner by making appropriate design changes.

9 [Effects of the Invention] As described above, since the present invention is an angle measuring device for a folding machine as described in the claims, it can be implemented in a folding machine.
The workpiece W being bent can be measured with high precision at any position inside the end face of the workpiece.

Furthermore, since measurement can be performed at any arbitrary position relative to the length of the workpiece W, the representative value of the bending angle of the workpiece can be known, and a remarkable effect is achieved in that automatic bending can be put to practical use.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a mold mounting structure for an imaging device according to an embodiment of the present invention, FIG. 2 is a front view of a bending machine equipped with an angle measuring device, and FIGS. A front view and a right side view of the imaging device shown in FIG. 1, FIG. 5 is an explanatory diagram modeling FIG. 4, and FIG. 6 shows the optical relationship of the embodiment shown in FIGS. Explanatory diagram, Figure 7 (a), (b), (c)
are the plan view, front view, and right side view of Fig. 6, Fig. 8 is a block diagram of the image processing device, Fig. 9 is a flowchart showing the angle measurement algorithm, and Fig. 10 is the mounting structure of the imaging device. FIG. 11 is an explanatory diagram showing a model of the embodiment shown in FIG. 10, FIG. 12 is an explanatory diagram showing a model of still another mounting structure of the imaging device, and FIG. FIG. 3 is a perspective view of a workpiece in which a phenomenon has occurred. 5...Die 6...Punch 9 (9F, 9B)...Imaging device 10...Image processing device 14...Laser diode 15...Visual sensor 24...NC device W... Workpiece WF...Front surface of the workpiece WB...Back surface of the workpiece Pp, Pa...Light ray pattern SL...Slit light αP, αB...Inclination angle β...Irradiation angle of the slit light B ZF s Special JP-A-3 259705 (8) Figure 7 (b) 9 Figure 7 (C) JP-A-3 259705 (11)

Claims (6)

[Claims] (1) A plate-shaped workpiece is interposed between a mold consisting of a punch and a die, and the workpiece is bent back and forth with respect to the bending line of the mold by relative approaching and separating movements of the punch and die. In the angle measuring device for a bending machine, the corresponding surfaces of the workpiece are used as measurement surfaces in front and rear of the mold, and the measurement surfaces are irradiated with planar light by scanning a slit light or a linear beam. , an imaging device is provided for imaging a linear light beam pattern appearing on the surface to be measured on a plane coordinate from an imaging direction that has a fixed relationship with the surface to be measured and the surface irradiated with the planar light, and each imaging device captures an image. an image processing device that determines the bending angle of the workpiece by synthesizing the inclination angles of each measurement target surface with respect to each imaging direction determined from the angle made with respect to the reference line of the light beam pattern on the plane coordinates that are An angle measuring device for a bending machine characterized by the following. (2) In claim 1, a three-dimensional
Considering Z, the irradiation surface is a surface obtained by tilting the YZ plane by an angle β toward the The inclination angle α of the surface to be measured with respect to the Z axis is α=tant^-^1(tanθ・tanβ
) An angle measuring device characterized by the following: (3) The angle measuring device according to claim 2, characterized in that α=θ by setting β=45 degrees. (4) The angle measuring device for a bending machine according to claim 1, wherein the imaging device is movable in the left and right directions with respect to the mold. (5) In claim 1, the angle bending machine is characterized in that a plurality of the imaging devices are provided at appropriate intervals in the left-right direction with respect to the mold, and are switched and used as appropriate for a portion to be measured. Measuring device. (6) In claim 1, a plurality of said imaging devices are provided at appropriate intervals in the left-right direction with respect to said mold, and the measured angle is an average value of angle data measured by the plurality of imaging devices. Angle measuring device for bending machines.