JPH04145315A - Bending device capable of detecting bend angle - Google Patents

Abstract

PURPOSE:To precisely bend a plate material to a desired bend angle by calculating the bend angle of the plate material based on the inclination angle signal outputted from a visual sensor, and controlling the position of an upper die or a lower die based on the bend angle signal. CONSTITUTION:The image data of the inclination angle of a linear radiation section measured and stored by a visual sensor constituted of an image receiver such as a CCD camera 12 and a frame memory are fed to an arithmetic processing means and arithmetically processed here, thus the bend angle thetais calculated. The value of the calculated bend angle theta is compared with the target bend angle, and the bend angle theta is correction-calculated in the next stage based on the difference. A drive section with a driving system is controlled, and a ram is vertically moved to adjust the position of an upper die 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bending device capable of detecting a bending angle, and more specifically, the present invention relates to a bending device capable of detecting a bending angle. The present invention relates to a bending device that detects angles.

[Conventional technology]

Mechanisms for detecting bending angles of plate materials by bending machines can be roughly divided into contact methods and non-contact methods.

As the former, Japanese Patent Laid-Open No. 1-273618 discloses a continuous tracking angle detection device using a rectangular link. In this device, the inclination of the probe in contact with the inclined surface is read by an encoder located within the link mechanism.

In the latter case, it has conventionally been common to detect the bending angle from the difference in distances measured by a plurality of distance sensors. A distance sensor using a capacitance sensor is disclosed in JP-A-64-2723, an eddy-current sensor is disclosed in JP-A-63-49327, and a distance sensor using an optical sensor is disclosed in JP-A-1989-1. It is disclosed in the publication No.-271013.

[Problem to be solved by the invention]

In the case of the contact method described in JP-A-1-273618, the angle is measured by bringing the plate into contact with the probe, so if the plate is thin, the plate will bend due to contact, making it difficult to measure the angle accurately. It is. In addition, wear or deformation occurs in the probe due to aging. Furthermore, in order to improve measurement accuracy, the plate material must have a certain length, and a relatively large measurement space must be secured.

Conventionally, in a non-contact bending angle detection mechanism, the angle is calculated from the difference in distance, so the distance sensor needs to have high resolution. Moreover, JP-A-64-2
The output of the capacitance sensors and eddy current sensors described in JP-A No. 723 and JP-A-63-49327, respectively, changes depending on the surface condition of the measurement surface of the plate material. Requires revision every time there is a change. Furthermore, in a device that uses an optical sensor as a distance sensor, such as the one described in Japanese Patent Application Laid-open No. 1-271013, depending on the surface condition and material of the plate, light may be scattered or absorbed, resulting in large measurement errors. There are also problems such as insufficient detection accuracy.

Therefore, the object of the present invention is to provide a plate material that is not subject to change over time, regardless of its material, thickness, length, or surface condition.
It is an object of the present invention to provide a bending device capable of bending to a desired bending angle with high precision.

[Means to solve the problem]

Since angle detection using a contact method has a problem with detection accuracy as described above, bending angle detection will be performed using a non-contact method using light and visual sensors. In addition, with the conventional non-contact method that detects the bending angle from the difference in distance, the detection accuracy and sensitivity vary depending on the condition of the measurement surface. If image processing is performed using a sensor, it is possible to accurately detect the angle regardless of the state of the measurement surface.

Therefore, in order to solve the above object, the present invention provides a bending machine that bends a plate material inserted between an upper die and a lower die, in which a) a slit light or a plurality of spots arranged in series are applied to the plate material; a) a light source that emits light obliquely at a predetermined irradiation angle; b) a visual sensor that reads the inclination angle of the linear irradiation part by the projected light beam on the plate material at a predetermined light receiving angle; d) a control means for adjusting the position of the upper die or the lower die based on the bending angle signal outputted from the arithmetic processing means; The main point is to be prepared.

[For production]

The plate material inserted between the upper mold and the lower mold is bent as the upper mold descends or the lower mold rises.

In the first step, the plate is bent at an angle smaller than the target bending angle, taking into account the elasticity inherent in the plate. When the plate is bent to a certain extent, a slit light or a plurality of permuted spot lights are projected onto the plate. At this time, the slit light or the line connecting the plurality of spot lights is linearly irradiated onto the plate material at an inclination angle corresponding to the bending angle of the plate material. Therefore, the inclination angle can be measured by capturing an image of the linear irradiation portion on the plate material using a visual sensor and processing the image. Furthermore, the bending angle of the plate material at that point in time is calculated by calculating the obtained inclination angle of the linear irradiation section together with the preset irradiation angle and light reception angle. This bending angle is output as a signal to the control means for the position of the upper die or lower die, and the plate material can be bent to a predetermined angle by performing a pressing operation with the upper die or lower die until the target bending angle is reached. can.

〔Effect of the invention〕

According to the present invention, a bending angle detection means using an oblique light beam projected onto a bent piece of a plate material has been established. Since it is a non-contact method, there is no wear or deformation of the contacts due to changes over time, and stable measurement accuracy can be obtained even for thin plates. Also,
Accuracy is high because the inclination angle is directly read by image processing of the linear irradiation section. Moreover, the accuracy and sensitivity are not affected by the material or surface condition of the plate, and therefore there is no need to calibrate the sensor as in the conventional example. Further, the visual sensor is not required to have high resolution as in the conventional example. Furthermore, the angle can be detected with high precision even in a narrow detection space.

[Example] Next, an example of the present invention will be described with reference to the drawings.

The bending device 1 shown in FIG. 1 includes a lower die 3 supported by a pedestal 8, a ram 7 provided opposite to and above the lower die 3 so as to be movable up and down, and a ram 7 attached to the ram 7. This is an example having an upper mold 2. The plate material W to be bent is inserted between the upper die 2 and the lower die 3, and when the upper die 2 descends and is bunched, the plate material W is pinched between the upper die 2 and the lower die 3, and further W'' It bends like this.

Further, on either side of the lower die 3, a light source 11 and an image receptor such as a CCD camera 12 are attached on a bracket 10 supported by a backstop 9. These light sources 1
1 and the image receptor 12 are both movable back and forth, left and right,
The angle of the plate material W can be detected at any position depending on the size of the plate material W, etc. A slit light 13 such as a laser beam is irradiated obliquely onto the plate material W from the light source 11 . The linear irradiation portion of the light irradiated onto the plate material W is imaged by the CCD camera 12, displayed on the monitor screen of the CCD camera, and stored in a frame memory or the like as image data.

Then, the inclination angle of the linear irradiation section is measured by image processing.

In the embodiment shown in FIG. 1, the upper die 2 descends and the plate material W is pressed between the upper die 2 and the lower die 3, but in another embodiment, the lower die 3 rises and the plate material W rises. It may also be configured to be pressed between the mold 2 and the lower mold 3.

Even in such an embodiment, since the light source 11 and the image receptor such as the CCD camera 12 can be installed in a fixed positional relationship with respect to the lower mold 3, there is no problem in measuring the angle of the linear irradiation section. does not occur.

The image data of the inclination angle of the linear irradiation section measured and stored by a visual sensor having an image receptor such as a CCD camera 12 and a frame memory in this manner is sent to a calculation processing means, where it is subjected to calculation processing. By this, the bending angle is calculated. The principle of arithmetic processing in the case of slit light will be explained as follows.

First, as shown in Fig. 2, the irradiation angle of the light beam on the plate material W before bending is β, and the light receiving angle of the CCD camera is T.
, the bending angle of the plate material W' after bending is θ, and the inclination angle of the linear irradiation portion on the monitor screen is α. The relationship among the plate material W or W', the slit light, and the CCD camera in this case is schematically shown in FIGS. 2(a), (b), (C), and (d). In FIG. 2, (a) is a front view, (b) is a side view, and (C) and (d) are bottom views, that is, images displayed on the monitor screen. From this, the following formula 2 is derived.

In addition, as shown in FIG. 3 (a) as a front view, (c) as a side view, and (c) as a bottom view, the light source 11 and the CCD camera 12 are arranged parallel to the plate material W, If the angle between the axis of the slit light irradiation light source 11 and the axis of the CCD camera 12 that receives the light is δ, and the angle between the plate material W before bending and the plate material W′ after bending process is φ, equation 0 can be further expressed as a clause. Simply tanα= tanφ゛tanδ
■It becomes. Note that after this bending process, θ T=90' φ=90° −−δ=90′ −β
There is a relationship like this.

Therefore, by setting β, γ, or δ in advance using the 0 formula or the 0 formula, and measuring α by image processing, the θ value (or φ value), that is, the bending angle of the plate material can be calculated. Note that if β=45° and T=90° from the above equation 0, then the inclination angle α of the linear irradiation part will be twice as large as the bending angle θ.

The value of the bending angle θ calculated in this manner is compared with the target bending angle, and the bending angle in the next stage is corrected from this difference. When trying to achieve the target bending angle with high precision, in this correction calculation,
The amount of springback expected during the next stage of bending (
The bending angle for the next stage is calculated by taking into consideration the amount by which the given deformation is reversed due to the inherent elasticity of the plate material. The springback amount may be programmed to be calculated from the material and plate thickness input for each case based on previously stored data obtained through experience or calculation.

The bending angle at the next stage calculated by the correction calculation is output as a signal to a control means that controls the position of the upper mold 2. This control means controls a drive unit equipped with a drive mechanism such as a hydraulic or air cylinder, and moves the ram 7 up and down to change the position of the upper mold 2 (C) (if the lower mold 3 is movable, change the position of the lower mold 3).
It is supposed to be adjusted.

In the above-mentioned embodiment, a slit light was used to reveal the linear irradiation part, but as shown in FIG. The light spots 15.15'' at both ends may be connected as a line, and the inclination angle α may be detected by image processing of the connecting line.

Further, in this embodiment, light was emitted and images were taken from the bottom/left side of the plate material W, but if this is done from the bottom/center, the number of calculation elements can be reduced, the bending angle θ can be measured, and the measurement accuracy can be improved. It is also possible to project light and take images from the side or above. Furthermore, as a light source, it is also an effective means to use an infrared laser in order to reduce the influence of disturbance light.

Next, a control method for bending the plate material W using the bending device shown in FIG. 1 will be explained using a flowchart shown in FIG. 4.

First, in step 20.21, data regarding the thickness and material of the plate W to be bent is input. Also,
In step 22, the irradiation angle β of the light source 11 and CC
Input the light receiving angle T of the D camera 12. Furthermore, in step 24, a predetermined target bending angle θ is input and bending is started.

In step 25, the first stage of bending, the upper mold 2 is lowered at high speed to perform preliminary bending. The bending angle at this time is smaller than the target bending angle θ because a springback phenomenon is inevitable, and is set to 1, for example, θ−Δθ (the value of Δθ is usually about 0 to 4 degrees). In step 26 after the preliminary bending, the lowering speed of the upper mold 2 is made low, and the upper mold 2 is gradually brought closer to the lower mold 3 to proceed with the bending. - On the other hand, the data on the thickness and material of the plate material input in steps 20 and 21 are sent to step 27, where the amount of springback is predicted.

This data is output as a correction signal.

Next, the process proceeds to step 28, in which the slit light 13 is projected from the light source 11 onto the bent plate material W''.

The CCD camera 12 captures an image of the linear irradiation portion that is generated by projecting light onto the plate material W, and the inclination angle α of the linear irradiation portion is measured by image analysis (step 29). The obtained inclination angle α is sent as a signal to the arithmetic processing means, and step 3
0, the illumination angle β of the light source 11 input in advance, C
Arithmetic processing is performed based on the light receiving angle γ of the CD camera 12 and the equation 0, for example. The value of the bending angle θ calculated by this calculation is compared with the target bending angle value θ, and if θ≠θ, the process returns to step 27, and correction is made by adding the springback amount to the difference between θ and θ. The calculation is sent to the position control means of the upper mold 2, and step 26 is performed again. θ
If =θ, the process proceeds to step 31, where the upper mold 2 separates from the lower mold 3 and the bending ends.

In a configuration in which the upper die 2 is fixed and the plate material W is bent by the rise of the lower die 3, the operation is performed with the upper die and the lower die being replaced in the flowchart shown in FIG.

1 unit ■ 5PCC A 1.2t plate was bent with a leg length (width of a piece of bent plate) of 30m and a target bending angle of 90°±15''.At that time, first, the bending angle was approximately 88°. The upper die 2 applied bending pressure to the lower die 3 to create a so-called punch stroke.Here, in order to obtain a linear irradiation area on the bent piece of the plate, a semiconductor laser was applied. From λ = Q, 8- infrared laser beam is applied to the plate material at an irradiation angle β = 45° and a slit size of 2 m.
Light was projected at x10mm. Next, an image of the linear irradiation area on the plate material was captured using a 480 x 512 pixel CCD camera so that the light receiving angle γ was 90°. Image processing was performed using a BLOBut image processing device manufactured by Creative System Co., Ltd., and the bending angle θ was measured. The time required for this measurement was about 1 second. A correction calculation is performed that takes into account the difference between the bending angle at this time and the target bending angle, the pressing stroke of the upper mold 2 in the three directions of the lower mold, and the predicted amount of springback, and the upper mold 2 is adjusted so that the bending angle is 90°. was further brought closer to the lower mold 3. After performing the bending operation in this manner, the bending angle of the plate material was 90°5°. As a result of continuously bending 10 sheets in the same manner, the average bending angle was 90°±13°, with little variation and sufficiently satisfactory accuracy.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing one embodiment of the present invention, Figure 2 (a)
, (b), (C) and (d) are diagrams each schematically showing the main parts of FIG. FIG. 4, which is shown similarly to the figure, is a flowchart showing the operation of the apparatus of the embodiment. 1--------------Bending device 2--・--------Top mold 3--Bottom mold 7-- Ram 11--...--Light source 12--CCD camera 13--11--Slit light 15, 15'--... Spot light W----Plate material (before bending) w'------Plate material (after bending)

Claims (1)

[Claims] In a bending machine that bends a plate material inserted between an upper die and a lower die to a required angle, a) irradiating the plate material with a slit light or a plurality of serial spot lights in a predetermined manner; b) a visual sensor that reads the inclination angle of the linear irradiation part by the projected light beam on the plate material at a predetermined light receiving angle; and c) the inclination angle signal output from the visual sensor. d) a control means for controlling the position of the upper die or the lower die based on the bending angle signal output from the arithmetic processing means; A bending device that can detect the bending angle.