JPH0569046A - Metallic plate bending device - Google Patents

Abstract

PURPOSE:To bend a metallic plate to a necessary angle with regard to the metallic plate bending device for bending a metallic plate inserted between the upper die and the lower die. CONSTITUTION:While a metallic plate W is bent to a necessary angle, two linear projection images S, R formed by projecting light onto the bent outside surface Wa of the metallic plate W from a slit-like reference light source 9 and a detecting/measuring light source 8 are photographed by an image pickup means 10. On this photographed image, the linear projection image by the reference light source 9 forms a desired prescribed angle irrespective of a bending angle of the metallic plate, and on the other hand, the linear projection image by the detecting/measuring light source 8 is deflected and moved in connection with a variation of the bending angle, and becomes parallel to the linear projection image by the reference light source, when the metallic plate is bent to a necessary angle. With regard to such an image, a prescribed arithmetic processing is executed by an arithmetic means, and based on a result of this operation, the upper die or the lower die is controlled by a controller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal plate bending apparatus for bending a metal plate inserted between an upper mold and a lower mold at a required angle.

[0002]

2. Description of the Related Art A bending angle detecting mechanism in a conventional metal plate bending apparatus for a metal plate is roughly classified into a contact type and a non-contact type. As an example of the contact type detection mechanism, a continuous tracking angle detection device applying a square link described in Japanese Patent Laid-Open No. 1-273618 is disclosed, and an inclined surface of a metal plate is provided by an encoder provided in the link mechanism. The bending angle of the metal plate is detected by reading the inclination of the contact point that comes into contact with.

Further, the non-contact type detection mechanism is generally a method of detecting a bending angle from a difference in the distance to a bent metal plate by a plurality of distance sensors.
The one using an eddy current sensor as a distance sensor in JP-A-63-49327 and the one using an electrostatic capacitance sensor as a distance sensor in JP-A-64-2723 are disclosed in JP-A-1-71013. Japanese Patent Application Laid-Open No. 2004-242242 discloses an optical sensor as a distance sensor.

[0004]

However, in the contact type bending angle detection mechanism as described in the above-mentioned Japanese Patent Application Laid-Open No. 1-273618, a relatively long bending angle is required to ensure measurement accuracy. Since it requires a leg length, it is difficult to apply it to a metal plate with a short leg length, and if it is used for a longer period of time, the contact point of the contact point with the metal plate will be worn and deformed and the measurement accuracy will decrease. There is a problem that the measurement space is limited. Further, in the case of a thin metal plate, there is a problem that it is difficult to accurately detect the bending angle because the metal plate bends due to contact with the probe.

Further, in the non-contact type bending angle detecting mechanism, the eddy current sensor described in JP-A-63-49327 and the capacitance sensor described in JP-A-64-2723 are used. When used, the output changes depending on the material of the metal plate, so that there is a problem that the measurement condition must be changed every time the material of the metal plate changes. Further, in the one using the optical sensor described in Japanese Patent Laid-Open No. 1-271013, there is a problem that the irradiation light is scattered depending on the surface state of the metal plate to increase the measurement error or decrease the measurement accuracy. There is.

In order to solve the above problems, the present invention does not depend on the leg length of the metal plate, and even if the material of the metal plate changes, the bending angle can be accurately adjusted during the bending process. An object of the present invention is to provide a metal plate bending apparatus that detects and bends a metal plate at a desired angle.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a metal plate bending apparatus according to the present invention folds a metal plate inserted between an upper die and a lower die at a required angle. In the bending apparatus for bending a metal plate, (a) imaging means for imaging the bent outer surface of the metal plate while the metal plate is bent to a required angle, (b) the metal plate is bent to a required angle. In the meantime, a slit-shaped reference for projecting light onto the bent outer surface of the metal plate to form a linear projected image of a desired constant angle on the image captured by the imaging means regardless of the bending angle. A light source, (c) while the metal plate is bent to a required angle, light is projected onto the bent outer surface of the metal plate, and the bending angle changes on the image captured by the imaging means. When turning and moving, and the metal plate is bent at the required angle A slit-shaped inspection light source forming a linear projection image parallel to the linear projection image by the reference light source, (d) a linear projection light by the reference light source and the inspection light source imaged by the imaging means, Storage means for storing an image including a light image, (e) based on an image stored in the storage means while the metal plate is bent to a required angle, the two linear projections on the image. An arithmetic means for calculating an angle formed by an image, and (f) a control means for controlling the position of the upper die or the lower die based on the arithmetic result obtained by the arithmetic means. ..

Further, it is preferable that the inspection light source, the reference light source, and the image pickup means are moved in parallel with the bending line of the metal plate.

[0009]

While the metal plate is bent to the required angle, two linear projection images are formed by projecting light from the slit-shaped reference light source and the inspection light source onto the bent outer surface of the metal plate. The projected image is captured by the image capturing unit, and the captured image is stored in the storage unit. On this image,
The linear projection image from the reference light source forms a desired constant angle regardless of the bending angle of the metal plate, while the linear projection image from the inspection light source turns and moves as the bending angle changes. When the plate is bent at the required angle, it becomes parallel to the linear projection image by the reference light source. Therefore, while bending the metal plate, a linear projection image projected on the bent outer surface is captured, the angle formed by these two linear projection images in the captured image is calculated by the calculation means, and this calculation is performed. Based on the result, the control unit controls the upper mold or the lower mold, and when the two linear projection images are parallel, the movement of the upper mold or the lower mold is stopped and the metal plate is bent at a required angle. You can

Further, if the inspection light source, the reference light source and the image pickup means are respectively moved in parallel to the bending line of the metal plate, the bending angle can be detected at an arbitrary position on the bending outer surface of the metal plate. be able to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the position of the metal plate bending apparatus of the present invention will be described with reference to the drawings. In the metal plate bending apparatus 1 shown in FIGS. 1 and 2, a lower die 3 supported by a pedestal 2 and a ram that is provided above the lower die 3 so as to be movable upward and downward. The metal plate W inserted between the upper mold 5 and the lower mold 3 and placed on the lower mold 3 is bent by the upper mold 5 attached to the tip of the mold 4. The metal plate W is clamped by the upper die 5 and the lower die 3 as the ram 4 descends, and is bent at a required angle as shown by the solid line. The bending angle is determined by the lowest position where the ram 4 descends (the position of this ram is hereinafter referred to as the bottom dead center of the ram). The ram control device for controlling the lifting and lowering of the ram 4 is not shown in FIG. Further, on the bracket 7 supported by the backstop 6 provided on the side of the lower mold 3, a slit-shaped projection for projecting the linear projection images R and S on the bent outer surface Wa of the metal plate W is formed. Inspection light source 8 and reference light source 9, each of these light sources 8,
The linearly projected images R and S by 9 are imaged, for example, 480 × 51
A 2-pixel CCD camera 10 is installed. The light sources 8 and 9 and the CCD camera 10 are capable of adjusting the angle between the bent outer surface Wa of the metal plate W and the bent line Wb of the metal plate W.
It is possible to move in parallel to. The slit-shaped inspection light source 8 and the reference light source 9 are a semiconductor laser 11 that emits parallel light having a wavelength of 0.8 μm, and 2 mm (short side) × 10 mm (long side) provided on the optical path of the semiconductor laser 11. And a slit plate 12 having a slit.

Further, as shown in FIG.
The image captured by the camera 10 is displayed on the monitor TV 14 via the calculation unit 13 and is also stored in the storage unit 15 as image data, and the image data is calculated by the calculation unit 13 from the external input unit 16. The bending angle is calculated by taking into account the conditions as well. The bending angle obtained by the calculation is given to the ram control device 17,
In the ram control device 17, the bottom dead center of the ram is controlled and the metal plate W is bent at a desired angle.

By the way, as shown in FIGS. 4A, 4B, and 4C, a line formed by projecting light from the slit-shaped light source 20 onto the bent surface Wa of the metal plate W in general. When the linear projection image is captured by the CCD camera 10, the projection image angle α of the linear projection image U ′ on the captured image is the bending angle θ of the metal plate W, the projection angle β of the slit light, and the CCD. The imaging angle γ of the camera 10 is expressed by the following equation (1). tan α = sin (90 ° −θ / 2) / [tan β ・ sin (γ + 90 ° −θ / 2)] (1)

Each angle will be described in detail as follows. Projection angle β of the slit light: Before the metal plate W is bent (θ = 180 °), the long side is orthogonal to the bending line Wb placed at a position having an optical axis parallel to the bending line Wb. When the light source having the slits is projected from a position on the bending outer surface Wa which is turned downward by an angle β around a straight line orthogonal to the bending line Wb, the bending outer surface Wa and the slit light are polarized. The angle formed by the plane.

Imaging angle γ: Before the metal plate W is bent (θ = 180 °), the imaging surface has an imaging axis orthogonal to the bending line and is placed at a position orthogonal to the bending outer surface Wa. When the CCD camera 10 is imaged from a position rotated downward by an angle γ around the bending line, the bending outer surface W
The angle between a and the imaging axis.

Projected image angle α: An angle formed by a vertical line and a long side of the linear projected image R ′ on the image captured by the CCD camera 10.

However, in the equation (1), β = 45 ° and γ =
If it is 90 °, equation (1) is simplified to equation (2) and
It is expressed as in equation (3). tan α = cos (θ / 2) / sin (θ / 2) ＝ cot (θ / 2) ＝ tan (90 ° −θ / 2) (2) ∴α = 90 ° −θ / 2 (3)

Therefore, the linearly projected image R formed by projecting light from the light source 20 onto the bent surface Wa of the metal plate W at the projection angle β is imaged by the CCD camera 10 at the imaging angle γ. On the image, as the metal plate W is bent, the linear projected image U ′ moves so as to turn, and the projected image angle α depends on the bending angle θ of the metal plate W and the above-mentioned formula (1) α = 90. ° −
Expressed as θ / 2.

On the other hand, when the optical axis of the light source 20 and the image pickup axis of the CCD camera 10 are parallel to each other, the linear projection image angle on the image is constant regardless of the bending angle θ of the metal plate W.

In consideration of the relationship between the bending angle of the metal plate W and the projection image angle on the image as described above, in the present embodiment shown in FIG. 5, the projection angle β in the above equation (1) is used. = 45
The inspection light source 8 is placed at the position of °, and C is placed at the position of the imaging angle γ = 90 °.
Set the CD camera 10 and the optical axis of the reference light source 9 is C
The reference light source 9 is set at a position parallel to the image pickup axis of the CD camera 10. When the linear projected images R and S projected from the inspection light source 8 and the reference light source 9 onto the bent outer surface Wa of the metal plate W are imaged in such a positional relationship, on the image shown in FIG. , The linear projection image S ′ by the reference light source 9 which is turned around the optical axis by a required angle δ has a constant projection image angle δ (= of the reference light source 9 regardless of the bending angle θ of the metal plate W). The linear projection image R ′ by the inspection light source 8 is represented by a rotation angle δ) and is represented as a projection image angle ε that changes depending on the bending angle θ of the metal plate W.

Therefore, on the image taken when the metal plate W is bent at the target bending angle, the projection image angle ε of the linear projection image R ′ by the inspection light source 8 and the reference light source 9 are obtained.
If the reference light source 9 is set to the turning angle δ so that the light projection image angle δ of the linear light projection image S ′ according to the above is set, the predetermined image processing is performed while the ram 4 is lowered and the linear light projection is performed. Light image R '
And the linear projection image S ′ are parallel to each other, and the angle formed by these linear projection images R ′ and S ′ is 0 °, that is, the projection image angle ε = the projection image angle δ. Is required. Since this point becomes the bottom dead center of the ram 4, if the ram control device 17 controls the ram 4 to stop descending at the bottom dead center, the metal plate W can be bent at a desired angle. You can

In order to bend the metal plate W to a target angle, it is necessary to bend the metal plate W to an angle slightly smaller than the target bending angle in anticipation of the return angle due to springback. This springback amount is obtained empirically by the material of the metal plate W, the plate thickness, etc., and in the actual bending process,
The goal is to bend to a corrected bending angle that takes this springback amount into consideration.

Next, the step of bending the metal plate W using the metal plate bending apparatus 1 of the present invention will be described with reference to the flow chart shown in FIG. Step A: Input measurement conditions such as the plate thickness, material, and target bending angle θ of the metal plate W using an external input device. Step B: Corrected bending angle θ ′ considering the springback amount of the metal plate W based on the measurement conditions input in Step A, rotation angle δ of the reference light source (= 90 ° −θ ′ / 2)
, Find the ram lowering speed switching point. The springback amount is determined by the data stored in the storage unit. In addition, the ram lowering speed switching point is to lower the ram 4 at a high speed just before the bottom dead center of the ram in order to perform bending quickly, and then gradually and slowly to the bottom dead center of the ram while detecting the bending angle. This is to lower it. Step C: The reference light source 9 is rotated by an angle δ to set the linear projection image S ′ by the reference light source 9 on the image to the projection image angle δ. Step D: The linearly projected image S projected on the bent outer surface Wa is captured by the CCD camera 10, and the linearly projected image S ′ on the image is given to the storage unit 15 as image data and is also monitored. It is displayed on TV. Step E: Image processing to be described later is performed on the obtained image data to obtain a linear expression P representing the linearly projected image S ′ by the reference light source 9 on the image, and the linear expression P is stored in the storage unit. Step F: After lowering the ram 4 at a high speed to the ram lowering speed switching point, the ram lowering speed is switched to a lower speed. Step G: The ram 4 is lowered at a low speed for a small stroke. Step H: The CCD camera 10 captures two linearly projected images S and R projected on the bent outer surface Wa, and the linearly projected images S ′ and R ′ on the image are stored as image data. It is given to the section 15 and displayed on the monitor TV 14. Step I: Of the obtained image data, the linear light projection image R ′ by the inspection light source 8 is subjected to image processing to obtain the inspection light source 8
A linear expression Q expressing the linearly projected image R ′ is obtained. Linear expression Q
The image processing method for obtaining the above is the same as the method for obtaining the linear expression P of the linear projected image S ′ by the reference light source 9 in step F, and therefore the description thereof is omitted. Step J: By the linear expression P obtained in step E and the linear expression Q obtained in the above step I,
The angle ω formed by the linear projected image S ′ and the linear projected image R ′ is obtained by calculation. Step K: If ω = 0, the linear projected image R ′ by the inspection light source 8 and the linear projected image S ′ by the reference light source 9 are parallel, and the metal plate W is bent at the corrected bending angle θ ′. The process proceeds to step L, and if ω ≠ 0, the process returns to step G for further bending. Step L: The ram 4 rises, and the bending angle of the metal plate W becomes the target bending angle θ due to the spring back, and the series of bending steps are completed.

Next, the image processing in step E will be described with reference to the flow chart shown in FIG. Step E-1: Pixels which are received as a linearly projected image S ′ by a certain threshold value on the coordinates corresponding to the image having 480 × 512 pixels (= points at the coordinates)
To extract. Step E-2: From the coordinate value group of these extracted points, a linear expression P representing the center line of the linear projection image S ′ in the long side direction is obtained by the method of least squares.

As described above, according to the metal plate bending apparatus 1 of the present invention, regardless of the surface state of the metal plate W, the bending leg length of the long side of the slit (10 mm in this embodiment) or more is obtained. If so, the metal plate W can be bent at a desired angle quickly with high accuracy. After completion of step J in the above-described series of bending steps, the reference light source 9 is moved in parallel with the bending line Wb of the metal plate W, and the two linear projection images S ′ are displayed on the monitor TV 14. By making R ′ coincide with R ′, it is possible to visually confirm that the metal plate W is bent at the corrected bending angle θ ′.

In this embodiment, the correction bending angle θ'is obtained by obtaining the angle ω formed by the linear projection image R'from the inspection light source 8 and the linear projection image S'from the reference light source 9.
However, the correction bending angle θ ′ may be detected by comparing the projection image angles ε and δ of these two linear projection images R ′ S ′. In this case, processing is performed so as to compare the slopes of the linear expressions P and Q representing the linear projection image R ′ S ′ of 2.

Further, in this embodiment, since the formula (1) is simplified, the projection angle of the inspection light source 8 is set to the position of 45 ° and the CCD camera 10 is set to the position of the imaging angle of 90 °. However, the present invention is not limited to these angles,
An arbitrary angle can be selected, and the rotation angle of the reference light source 8 may be determined by obtaining the relationship between the bending angle θ and the projected image angle α from the equation (1). Further, the inspection light source 8, the reference light source 9, and the CCD camera 10 can be moved in parallel with the bending line Wb of the metal plate W, and the bending angle can be detected at any position on the bending surface Wa.

[0028]

The metal plate bending apparatus of the present invention is provided with a metal plate W.
The present invention can be applied regardless of the surface state of the metal plate, and the metal plate W can be bent at a desired angle with high accuracy and quickly if there is a slight bending leg length.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a metal plate bending apparatus according to the present invention.

FIG. 2 is a partially enlarged view of the metal plate bending apparatus according to the present invention.

FIG. 3 is a block diagram illustrating a function of the metal plate bending apparatus according to the present invention.

FIG. 4 is a drawing generally showing an example of a positional relationship between a metal plate, a light source, and a CCD camera and an image, in which FIG.
Imaging angle of D camera, (B) is projection angle of light source, (C)
FIG. 4 is a drawing showing an angle of a projected image on an image.

FIG. 5 is a drawing showing a positional relationship among a metal plate, an inspection light source, a reference light source, and a CCD camera in this embodiment.

FIG. 6 is a drawing showing an image in this embodiment.

FIG. 7 is a flow chart diagram illustrating a bending step of the metal plate in the present embodiment.

FIG. 8 is a flowchart illustrating an image processing method according to this embodiment.

[Explanation of symbols]

 1 Metal Plate Bending Device 2 Frame 3 Lower Type 4 Ram 5 Upper Type 6 Back Stop 7 Bracket 8 Inspection Light Source 9 Reference Light Source 10 CCD Camera 11 Semiconductor Laser 12 Slit Plate 13 Calculation Unit 14 Monitor TV 15 Storage Unit 16 External Input Unit 17 Ram control device 20 Light source W Metal plate Wa Bending outer surface Wb Bending line R, R ', S, S', U'Linear projection image

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 7, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 5]

[Figure 6]

[Figure 8]

[Figure 4]

[Figure 7]

Claims (2)

[Claims] 1. A metal plate bending apparatus for bending a metal plate inserted between an upper mold and a lower mold at a required angle, wherein (a) the metal plate is bent while being bent to a required angle. Image pickup means for picking up an image of the bent outer surface of the plate, (b) While the metal plate is bent to a required angle, light is projected onto the bent outer surface of the metal plate, and the image picked up by the image pickup means is displayed. In the slit-shaped reference light source that forms a linear projected image of a desired constant angle regardless of the bending angle in (c), while the metal plate is bent to a required angle, on the bent outer surface of the metal plate. On the image picked up by the image pickup means, and is turned and moved along with the change of the bending angle, and when the metal plate is bent at the required angle, it is parallel to the linearly projected image by the reference light source. A slit-shaped inspection light source that forms a linear projection image, (d ) A storage unit that stores an image including the linearly projected images of the reference light source and the inspection light source that are captured by the image capturing unit, and (e) the storage unit while the metal plate is bent to a required angle. Calculating means for calculating an angle formed by the two linearly projected images on the image based on the image stored in the image, and (f) based on the calculation result obtained by the calculating means, A metal plate bending device comprising control means for controlling the position of the lower die. 2. The metal plate bending apparatus according to claim 1, wherein each of the inspection light source, the reference light source, and the image pickup means moves in parallel with a bending line of the metal plate.