WO2021154075A1

WO2021154075A1 - Angle measuring device for measuring an enclosed angle between two plate members.

Info

Publication number: WO2021154075A1
Application number: PCT/NL2021/050053
Authority: WO
Inventors: Eeltje Aize Draaisma
Original assignee: Delem, Van Doorne's Electronica Voor De Machinebouw B.V.
Priority date: 2020-01-28
Filing date: 2021-01-28
Publication date: 2021-08-05
Also published as: NL2024769B1

Abstract

Angle measuring device for measuring an enclosed angle between a first and second plate member, comprising a sensor arrangement, wherein the sensor arrangement comprises: a light source for transmitting a light beam; a directing means for directing the light beam in a multitude of directions; a detector configured for detecting a reflection of the light beam off the first or second plate member when, in use, an optical path is formed between the light source and the detector via the directing means and by means of a reflection on the first or second plate member; and a processing unit arranged for receiving direction signals from the direction means and detection signals from the detector for determining the enclosed angle, wherein the direction signals comprise information about the direction in which the light beam is directed by the directing means; wherein the angle measuring device further comprises an optical device configured for shaping a section of the optical path between the directing means and the plate members.

Description

Title: Angle measuring device for measuring an enclosed angle between two plate members.

Technical field

The invention relates to an angle measuring device for measuring an enclosed angle between two plate members.

Background

Known angle measuring devices for measuring an enclosed angle between a first and a second plate member, comprise a sensor arrangement, wherein the sensor arrangement comprises a light source for transmitting a light beam; a directing means for directing the hght beam in a multitude of directions; a detector configured for detecting a reflection of the light beam off the first or second plate member when an optical path is formed between the light source and the detector via the directing means and a reflection off the first or second plate member; and a processing unit arranged for receiving direction signals from the direction means and detection signals from the detector for determining the enclosed angle, wherein the direction signals comprise information about the direction in which the light beam is directed by the directing means. Such angle measuring device is known, for example from EP3303988B1.

In use of such an angle measuring device, the sensor arrangement is positioned in a corner space enclosed between the first and second plate member, wherein the transmitted light beam, in particular a laser beam, is reflected by means of a rotating mirror. The rotating mirror is rotatable around a rotation axis which is substantiahy in line with the laser beam being transmitted by the light source, wherein a flat reflective surface of the rotating mirror is positioned at an angle with respect to the rotation axis such as to direct the laser beam. By means of rotation, the rotating mirror is arranged to direct the laser beam in a multitude of directions, wherein the direction in which the laser beam is directed is governed by the orientation of the rotating mirror with respect to the transmitted laser beam. A reflection of the laser beam off the first or second plate member is detected with the detector if an optical path is formed between the light source and the detector via the directing means and via a reflection on the first or second plate member.

However, when the corner space is relatively tight compared to a size of the sensor arrangement of the angle measuring device, for example when the enclosed angle to be measured is relatively small, or when the corner space is hard to reach when the first and second plate members are part of a multi-bent plate body, it may be impractical or even impossible to suitably position the sensor arrangement in the corner space enclosed between the member plates (for providing accurate/reliable measurements of the angle). Moreover, when the angle measuring device is paired with a bending punch of a bending machine for inline measuring an inclined angle, i.e. while bending a plate body, the range of reachable corner spaces becomes particularly limited.

Summary

It is therefore an aim of the invention to provide an angle measuring device for measuring an enclosed angle between two plate members, that at least alleviates the above identified problems. In particular, it is an aim to provide an improved angle measuring device that can be widely employed, and specifically for measuring enclosed angles in situations or circumstances wherein the corner space enclosed between the plate members is hard to reach or too small/tight/narrow for known angle measuring devices. It is further preferred to provide a system of an angle measuring device and a bending punch that is able to reach and measure inclined angles in tight corner spaces.

Accordingly, a first aspect of the angle measuring device of the invention is characterised in that the angle measuring device further comprises an optical device configured for shaping a section of the optical path between the directing means and the plate members. The shape of the section of the optical path between the directing means and the plate members can be adapted to a particular configuration of the plate body and the enclosed angle to be measured. For example, in a multi-bent plate body, the section of the optical path may be shaped around plate body material, e.g. around corners and other obstructions, or can be shaped to fit trough narrow openings or slits in a multi-bent plate body, in order to deliver the light beam to the plate members that enclose the angle to be measured. Optionally, the optical device is configured for functionally recreating the directing means in a location further away from the sensor arrangement. Otherwise stated, the optical device creates a virtual directing means in a location further away from the sensor arrangement, in use, inside a tight corner space. Accordingly, the functionality of the directing means, i.e. directing the light beam in a multitude of directions, can be recreated within the (tight) corner space, close to the inclined angle to be measured whereas the directing means itself can be positioned outside of the corner space. For instance, the optical device can be arranged to extend, in use, the optical path between the directing means and the plate members in a direction away from the sensor arrangement. This way, the sensor arrangement of the angle measuring device can be positioned outside of a (tight) corner space or at least at a distance further away from the plate members, while the optical device shapes, in use, the optical path between the directing means of the sensor arrangement and the plate members, such that the light beam can be delivered to the plate members, and further allows the reflection of the light beam to reach the detector. The light beam transmitted by the light source of the sensor arrangement travels along the optical path including the shaped section, shaped by the optical device, from the detector to the plate members. The reflection of the light beam off either of the plate members continues the optical path to the detector, via the shaped section of the optical device. The optical device may for example comprise an optical wave guide for guiding, in use, the hght beam between the directing means and the plate members.

When the light beam is directed in a first particular direction by the direction means, the hght beam may follow a first optical path between the light source and the detector via the directing means, via the optical device, and via a reflection off the first plate member. Similarly, when the light beam is directed in a second particular direction by the direction means, the light beam may follow a second optical path between the light source and the detector via the directing means, via the optical device and via a reflection off the second plate member. Based on the direction signals of the directing means and corresponding detection signals of the detector, the enclosed angle between the first and second plate member can be determined by means of the processing unit. There may for example be a relation between the direction of the light beam in which it is directed by the directing means, and an angle of incidence and/or reflection of the hght beam on the first or second plate member. The directions in which the light beam is directed that led to a detection provides information on the orientations of the first and second plate members and hence the enclosed angle can be determined.

In an embodiment of the angle measuring device according to the invention, an optical axis of the optical device extends between a proximal end proximate the sensor arrangement and a distal end of the optical device opposite the proximal end, wherein in a direction transverse to the optical axis of the optical device, a cross section of the optical device is smaller than a cross section of a housing of the sensor arrangement in the same direction as the cross section of the optical device. The relatively small cross section of the optical device, with respect to the sensor arrangement, allows for applying the optical device in narrow access openings into tight corner spaces between the first and second plate member. In particular, the optical device may extend between a proximal end proximate the directing means and a distal end opposite the proximal end, wherein the optical device may be configured for receiving the light beam from the direction means at the proximal end of the optical device, guiding the light beam to the distal end, and submitting the light beam at the distal end in a direction towards the first or second plate member. The optical device may further be configured for receiving a reflection of the light beam off the first or second plate member at the distal end of the optical device, for guiding the light beam to the proximal end, and for submitting the reflection of the hght beam at the proximal end of the optical device. The reflection of the light beam may for example be submitted at the proximal end of the optical device to reach the detector via the direction means.

In a further embodiment of the angle measuring device, the optical device comprises optical means for refracting and/or a reflecting the hght beam and/or, in use, a reflection thereof off the first or second plate member, in a direction substantially along the optical axis. Such optical means enable shaping of the optical path between the directing means and the plate members, for example by redirecting the light beam substantially in a direction the optical axis away from the directing means. Also, a reflection of the light beam can be redirected back along the optical axis towards the detector of the sensor arrangement by the optical means. The optical means may for example comprise a refractive element, such as a lens, shaped such as to refract the light beam substantially along the optical axis of the optical device. Alternatively or additionally, the optical means may comprise a mirror for reflecting the light beam.

In yet a further embodiment of the angle measuring device, the optical axis is substantially curved, such that the optical path can be shaped around edges or other obstacles, such that the light beam can reach the plate members. For example, the optical axis can be shaped to match a curvature of a bending punch of a bending machine, for use in a multi-bent plate body. For example, the optical axis at the proximal end and the optical axis at the distal end of the optical device are parallel to each other, wherein the optical axis between the proximal and distal ends is curved. Optionally, the optical axis at the proximal end and the optical axis at the distal end of the optical device are oriented in different direction with respect to each other, wherein the optical axis between the proximal and distal ends is curved.

In another embodiment of the angle measuring device, the optical device comprises an optically transmissive body for refracting and/or a reflecting the light beam and/or, in use, a reflection thereof off the first or second plate member, in a direction substantially along the optical axis. The optically transmissive body can be shaped such as to change a direction of the light beam substantially along the optical axis of the optical device. Optionally, the optical device comprises multiple transmissive optical bodies. The optically transmissive body, or bodies, can be shaped and arranged to guide the light beam along a desired optical path for the light beam to follow. The light beam can for example be refracted at an outer surface of the optically transmissive body, when the light beam enter the optically transmissive body, to change direction of the hght beam. Also, the hght beam can travel trough an interior of the optically transmissive body, wherein the direction of the light beam can be altered by means of internal reflection at a boundary of the optically transmissive body, caused by a refractive index difference between the interior and an exterior of the optically transmissive body. Also, the light beam travelling through the optically transmissive body can be refracted at an outer surface of the optically transmissive body, when exiting the optically transmissive body.

In yet a further embodiment of the angle measuring device, that the optically transmissive body extends in axial direction of the optical axis between the distal end and the proximal end, wherein the opticahy transmissive body is substantially elongated in the axial direction. This minimises the number of transitions between materials of different refractive indices, thereby reducing scatter and/or secondary reflections of light that might arise at said transitions, possibly giving false or corrupted angle measurements.

In order to refract the light beam, with the optically transmisive body, in a desired direction, the optically transmissive body of a further embodiment of the angle measuring device comprises a proximal curved surface at the proximal end facing the directing means.

Optionahy, the optically transmissive body of the angle measuring device has a distal curved surface for facing the plate members, in order to refract the light beam. The curvature of the proximal and distal surfaces may be adapted to one another, such that a direction the light beam exiting from the distal curved surface is a function of a direction of the light beam entering the proximal curved surface of the optical device. Said function enables the determination of a relation between the direction in which the light beam is directed by the directing means and the direction in which the light beam is refracted by the distal curved surface. Specifically, said function enables the determination of a relation between the direction in which the light beam is directed by the directing means and the inclined angle between the first and second plate members. The relation between the direction in which the light beam is directed and the inclined angle can for example be determined by a calibration step. It is preferred to shape the proximal and distal curved surfaces such that said relation is a hnear. It is further preferred that the angle with respect to the optical axis at which the light beam is incident on the proximal curved surface is equal to the angle with respect to the optical axis at which the light beam exits the distal curved surface of the optical device.

According to an embodiment of the angle measuring device, the proximal curved surface is convex, wherein the proximal curved surface and the directing means are spaced a distance apart corresponding to a focal length of the optically transmissive body. The directing means can be positioned in a focal point of the optically transmissive body, wherein the directing means is arranged to direct the light beam from the focal point into a multitude of directions. Any light beam directed towards the optically transmissive body, and entering the optically transmissive body through the proximal curved surface, will be refracted by the convex or concave surface to travel parallel to the optical axis at the proximal end of the optically transmissive body. This way, a slender optical device can be obtained for positioning thereof in tight corner spaces. Also, further direction changes of the light beam can be easily achieved as the optical paths followed by the light beam are parallel after refraction by the convex or concave surface of the optically transmissive device. In a particular embodiment, the proximal curved surface is aspherically shaped to correct for spherical aberrations in the optical path.

In embodiments of the angle measuring device, the distal curved surface is convex or concave. The light beam guided from the proximal end to the distal end of the optical device may be redirected to hit and reflect off either of the two plate members. Also the reflected light beam may hit the distal curved surface of the optical device to be guided back towards the proximal end. Having a convex or concave proximal curved surface and a convex or concave distal curved surface allows for easy determination of the relation between a direction at which the light beam is incident on optical device and the direction at which the light beam exits the optical device.

Optionally, the proximal focal length and the distal focal length of the optical device are equal, such that a direction of the light beam in which it is directed by the directing means is effectively replicated at the distal side of the optical device between the optical device and the plate members. Otherwise stated, with equal focal lengths at the distal and proximal sides of the optical device, there is a one-to-one relation between the direction of the light beam directed by the directing means and the direction of light beam exiting the optical device at the distal end as if the directing means is virtually recreated at or near the distal side of the optical device. As such, the optical device creates a virtual directing means in a location further away from the sensor arrangement, such that in use, the light beam can be directed inside a tight corner space while the directing means is positioned outside of the corner space. The distal focal length can, alternatively, be shorter than the proximal focal length, which effectively amplifies the amplitude of a pivot angle of the rotatable mirror at the distal side of the optical device. This way, a larger range of enclosed angles can be measured, and particularly smaller enclosed angles can be measured. Moreover, the cross sectional area, transverse to the optical axis, of the optical device can be reduced to obtain a more slender setup. Alternatively, a distal focal length being larger than the proximal focal length decreases the amplitude of the pivot angle at the distal side and decreases the increment size between respective directions at the distal side of the optical device. This allows for a more precise measurement of the inclined angle.

In embodiments, a lateral cross sectional area substantially transverse to the axial direction of the optically transmissive body is substantially rectangular. The cross sectional area of the optically transmissive body may for example be square. The rectangular shape is suited for guiding the light beam, when the multitude of directions of the light beam lay in a single plane. The flat boundary of the optically transmissive body can internally reflect the light beam in a predictive manner, and maintains the light beam within said plane. Moreover, such cross sectional shape is particularly convenient for integrating the optically transmissive body with additional tooling, for example a probe or tooling of a bending machine, in particular a bending punch of a bending machine.

In an embodiment, a first width of the cross sectional area is substantially smaller than a second width of the cross sectional area. The first width being transverse to the second width. The optically transmissive body can be made substantially flat in a direction of the first width, e.g. a slab-shaped or planar optically transmissive body, to minimise the overah volume of the optically transmissive body. Preferably, the first width of the cross sectional area is larger than a cross section of the light beam to ahow the hght beam to enter and exit the optically transmissive body.

In a further embodiment, the directing means is arranged for directing the light beam in a multitude of directions a first scanning plane

corresponding to the scanning plane of the rotatable mirror. The optically transmissive body, or at least a part thereof, can extend in said first scanning plane, is arranged for directing at the distal end the light beam in a multitude of directions within said first scanning plane. For efficiency, the directing means may direct the light beam in the first scanning plane in a multitude of directions within an angular range of 0-180°. For a compact setup it is appreciated to orient the optically transmissive body relative to the directing means such that the direction of the second width is, at least substantially, aligned with the first scanning plane, for receiving at the proximal end the directed light beam from the directing means. The direction of the first width of the optically transmissive body can be oriented transverse to the first scanning plane, such that the first width can be minimised.

In an embodiment, the optical device is arranged for directing at the distal end the light beam in a multitude of directions within a second scanning plane different from the first scanning plane. The optical device may be arranged for refracting and/or a reflecting the light beam and/or, in use, a reflection thereof off the first or second plate member, out of the first scanning plane, for instance in a direction transverse to the first scanning plane. At the distal end of the optical device, the light beam may be directed into a multitude of directions within the second scanning plane, wherein the second scanning plane has a different orientation relative to the first scanning plane.

In embodiments, the angle measuring device is arranged to detect, with the detector, a reflection of the light beam off the first or second plate member when, in use, a transmission section of the optical path from the directing means to the first or second plate member substantially overlaps with a reflection section of the optical path from the first or second plate member to the directing means. The transmission section of the optical path is defined as the section of the optical path followed by the hght beam from the directing means to the first or second plate member; and the reflection section of the optical path is defined as the section of the optical path followed by the reflection of the light beam from the first or second plate member to the directing means. The light beam following the transmission section, and which hits the first or second plate member in a direction normal to the first or second plate member, wih be reflected in the same but opposite direction. Accordingly, the reflected light beam travels along the reflection section back to the directing means which reflection section overlaps with the transmission section. The light beam incident on the first or second plate member at any other direction relative to the first or second plate member, will follow the reflection section which does not overlap with the transmission section. Otherwise stated, the angle measuring device is arranged to detect, with the detector, a reflection of the light beam if the light beam is incident on the first or second plate member in a direction normal to said first or second plate member. A light beam that is incident on the first or second plate member any other direction is not reflected back to the camera, and thus filtered out. To capture the reflection of the light beam, a one way mirror or semi-transparent mirror or other suitable optical element may be employed between the directing means and the detector to redirect the reflection of the light beam towards the detector while the light beam from the hght source to the directing means can be transmitted there through.

In embodiments of the angle measuring device, the hght source is configured for transmitting a cohimated light beam, for example a laser beam.

The angle measuring device may be hand-held. Alternatively, in some embodiments, the angle measuring device further comprises a bending punch extending between a punch edge at a distal end of the punch and a proximal end opposite the distal end, for bending a plate body, which allows for inline measuring of a bending angle between two plate members of the plate body. The sensor arrangement of the angle measuring device can be attached to the bending punch, preferably at a position away from the corner space enclosed between the plate members, for example at the proximal end of the punch. Alternatively, the sensor arrangement may be provided at a face of the bending punch between the distal and proximal end. Additionally or alternatively, the optical device of the angle measuring device may be coupled to the bending means. For example, the optical device may be attached to a face of the bending punch between the distal and proximal end. The optical device may be integrated with the bending punch.

In some embodiments, the angle measuring device is characterised in that the bending punch comprises a cavity arranged for holding the optical device of the angle measuring device, wherein the cavity opens at the proximal and distal end of the punch for allowing the light beam to enter and exit the optical device.

In some embodiments, the angle measuring device is characterised in that, at the distal end of the punch, the cavity opens at two opposing lateral sides for, in use, allowing the light beam to be submitted to the first and second plate member and for allowing the reflection of the light beam to enter the optical device at the distal end of the punch.

In embodiments, the angle measuring device is characterised in that the cavity extends in a direction of the first and/or second scanning plane wherein the first and/or scanning plane is oriented transverse to the punch edge of the bending punch. The directing means are arranged to direct the light beam in a multitude of directions within the first scanning plane.

According to a second aspect of the invention, a system is provided for bending a plate body, wherein the system comprises a bending punch extending between a proximal end and a distal end, for bending a plate body, and an angle measuring device in accordance the first aspect of the invention, the system being configured for inline measuring of a bending angle between a first and second member of the plate like body. The bending punch may be any conventional punch, which is provided with a angle measuring device according to first aspect of the invention. The angle measuring device may be attached to a side of the bending punch.

Preferably, the sensor arrangement is provided at a location outside of the corner space enclosed between the plate members of the plate body, for example at the proximal side of the bending punch. The optical device may be attached to the bending punch in such a way to shape the section of the optical path between the directing means and the plat body in concordance with a shape of the bending punch. For example the bending punch may have a curved shape to provide a bend in a multi-bent plate body. The optical device may be shaped accordingly, to follow the curved shape of the bending punch in order to provide the light beam to and from the plate members of the plat body. The optical device may for example be provided at an end face of the bending punch. A bending die may also be provided that includes a bending slot for partially receiving the bending punch. The plate body may be provided on a bearing surface of the bending die, wherein, in use, the bending punch is moved partially into the bending slot thereby pressing down on the plate body and plastically deforming the plate body at the location of the bending punch and bending slot. As a result, two substantially flat plate members of the bended plate body extend from a bend edge to either side of the bend edge, at an enclosing angle. The system is configured to measure with the angle measuring device, the enclosed angle between the two plate members while bending the plate body. The measured enclosed angle may for example be used as a feedback signal for the bending system to obtain accurate bending angles of the plate body. In an embodiment of the system, the bending punch comprises a cavity arranged for holding the optical device of the angle measurement device, wherein the cavity opens at the proximal and distal end of the bending punch for allowing the light beam to enter and exit the optical device. Light can in this way be submitted to the plate members by means of the optical device through the bending punch, whereas the sensor arrangement of the angle measuring device can be provided a distance away from the bending punch, outside of the corner space.

Some embodiments of the system are characterised in that, at the distal end of the bending punch, the cavity opens at two opposing lateral sides for, in use, allowing the light beam to be submitted to the first and second plate member and for allowing the reflection of the light beam to enter the optical device at the distal end of the bending punch. This way hght can hit the first and second plate member, which extend on either side of the bending punch. Moreover, a working edge of the bending punch which is arranged for contacting the plate body during bending thereof, can remain uninterrupted along the length of the working edge, for evenly distributing and transferring a bending force over the length of the working edge to the plate body.

Further embodiments of the system are characterised in that the cavity extends in the first and/or second scanning plane wherein the first and/or scanning plane is oriented transverse to a punch edge of the bending punch The directing means are arranged to direct the light beam in a multitude of directions the first scanning plane.

Description of the Figures

The various aspects of the invention and embodiments thereof will now be discussed in conjunction with drawings. In the drawings: Figure 1 shows an embodiment of the angle measuring device;

Figures 2A and 2B show embodiments of the optical device of the angle measuring device;

Figure 3A and 3B show embodiments of the optical device of the angle measuring device;

Figure 4 shows an embodiment of the system including a bending punch and the angle measuring device;

Figure 5 shows an embodiment of a system for bending a plate body, comprising a angle measuring device and a bending punch.

Detailed description of the embodiments

Figure 1 shows the angle measuring device, wherein the optical device 1 is provided in a corner space between a first 3 and second 5 plate member of a plate body. A light beam 7, which is transmitted by a light source (not shown) is directed by a directing means 9. In the shown embodiment, the direction means 9 comprises a rotatable mirror 11 which is rotatable around a rotation axis 13. The rotatable mirror 11 is provided at an angle, in particular an angle of about 45 degrees, with respect to the rotation axis 13. The light beam 7 is transmitted to the directing means substantially along the rotation axis 13 of the rotatable mirror 11 such that the light beam 7 is directed by the rotatable mirror in a multitude of directions transverse to the rotation axis 13. More specifically, the rotatable mirror 11 is arranged to direct the light beam 7 into a multitude of directions within a first scanning plane 6. It is preferred that the rotatable mirror 11 pivots around the rotation axis 13 with a pivot angle, wherein the pivot angle is adapted to a dimension of the optical device 1. Preferably, the pivot angle is about 45 degrees.

The optical device 1 is arranged between the directing means 9 and the two plate members 3, 5, and extends between a proximal end 17 proximate the directing means 9, and a distal end 19 opposite the proximal end 17. At the proximal end 17, the optical device comprises a proximal curved surface 21, which is in particular convexly shaped, to refract the light beam 7 substantially along an optical axis 25 of the optical device 1. It is preferred to provide the directing means 9, in particular the rotatable mirror 11, at a (proximal) focal length from the optical device, more specifically in a focal spot of the optical device 1, such that the light beam directed by the directing means 9, is refracted substantially parallel to the optical axis 25 of the optical device 1. At the distal end 19 the optical device comprises a distal curved surface 23, in particular convexly shaped, to refract the light beam towards the first 3 or second 5 plate member. The light beam is refracted at the distal end of the optical device in a second scanning plane 8, wherein, in this example, the first scanning plane 6 and the second scanning plane 8 are identical. The optical device 1 is provided a distance from the plate members 3, 5, more specifically a distance from a bend edge 31 of the plate body, corresponding to more than a distal focal length of the optical device. It is preferred to position the optical device 1 in such a way that the distal focal point 35 is located between the distal curved surface 23 and the plate members 3, 5, to allow measuring of the enclosed angle between the plate members irrespective of the exact position of the optical device 1. In the particular embodiment of Figure 1, the proximal focal length and the distal focal length of the optical device 1 are equal, such that a direction of the light beam 7 directed by the directing means 9, is effectively replicated at the distal side of the optical device between the optical device 1 and the plate members 3, 5. Otherwise stated, with equal focal lengths at the distal and proximal sides of the optical device 1, there is a one-to-one relation between the direction of the light beam 7 directed by the directing means 9 and the direction of light beam 7 exiting the optical device 1 at the distal end. It is envisioned that the distal focal length is shorter than the proximal focal length, which effectively amphfies the amplitude of the pivot angle of the rotatable mirror 11 at the distal side of the optical device 1. This way a larger range of enclosed angles can be measured, in particular smaller enclosed angles can be measured. Alternatively, a distal focal length being larger than the proximal focal length decreases the amplitude of the pivot angle and thus decreases the step size at the distal side of the optical device 1. This allows for a more precise measurement of the inclined angle.

The optical device 1 comprises an optically transmissive body 15, which extends between the proximal end 17 and the distal end 19. In Figure 1, two optical paths are depicted, wherein a first optical path 27 extends via the directing means 9 to the first plate member 3, and a second optical path 29 extends via the directing means 9 to the second plate member 5. The light beam 7 can follow the first 27 or second 29 optical path from the light source, via the directing means 9, to respectively the first 3 or second 5 plate member. The light beam 7 may be reflected, in particular specularly, on the first 3 or second 5 plate member. When the light beam 7 is normally incident on the first 3 or second 5 plate member, i.e. perpendicular to the first 3 or second 5 plate member, the light beam 7 is reflected on the first 3 or second 5 plate member in the same but opposite direction. As such, the reflection of the light beam 7 travels along the same optical path back to the directing means 9. In the optical path between the light source and the directing means 9, a one way mirror, semi-transparent mirror, beam splitter or other optical device can be provided to separate the reflection of the light beam 7 from the light beam 7, and to direct the reflection of the hght beam 7 towards a detector (not shown). The light beam incident on either plate member at an angle not perpendicular to the respective plate member, will not be reflected in the same but opposite direction, but instead will be reflected in a direction related to the angle of incidence. Consequently, those reflections of the hght beam will either not reach the directing means 9, or will hit the direction means at angle such that it does it does not reach the detector.

The enclosed angle between the first 3 and second 5 plate member can be determined, for example by a processing unit of the angle measuring device, based on a detection of the reflection of the hght beam 7 by the detector which detection corresponds to a particular direction of the light beam 7 directed by the direction means 9. As shown in Figure 1, a first detection occurs when the light beam 7 follows the first optical path 27, and a second detection occurs when the light beam 7 follows the second optical path 29. Any other optical path is not detected, as those paths do not reach the directing means, and ultimately the detector. The first 27 and second 29 optical paths correspond to two respective directions in which the light beam 7 is directed by the directing means 9. Those directions at which the light beam 7 is directed, that led to a detection of the reflection of the hght beam, correlates to the enclosed angle between the plate members. Said correlation depends, for example on the particular configuration of the optical device, in particular on the shape of the optically transmissive body 15.

In the embodiment of Figure 1, the optical axis 25 is substantially straight and defined by the optically transmissive body 15 being substantially straight and elongated. The optical axis may also be curved, for example to be integrated with a bending punch of a bending machine. It is envisioned that the optical device 1 comprises two or more optically transmissive bodies. For example, a first optically transmissive body at the proximal end, and a second optically transmissive body at the distal end of the optical device being spaced from the first optically transmissive body. A space between the first and second optically transmissive bodies may be empty, or be provided with reflective optical elements for redirecting the light beam along an optical axis extending between the proximal and distal end. Figures 2A and 2B show the optically transmissive body 15, wherein the optical axis 25 is curved. In Figure 2A, the direction of the optical axis 25 at the proximal end 17 of the optically transmissive body 15 is changed with respect to the direction of the optical axis 25 at the distal end 19. This allows for angle measurements in hard to reach places where light has to be transmitted laterally with respect to a bending edge of the plate body. In this example, the first scanning plane 6 and the second scanning plane 8 coincide.

Figure 2B shows an optically transmissive body 15 wherein the optical axis 25 is at the distal end 19 is translated with respect to the optical axis 25 at the proximal end 17. The outline of the optically transmissive body 15 can be adapted to a shape of a bending punch of a bending machine. Here, the proximal 21 and distal 23 curved surfaces are convex. Alternatively, the distal curved surface may be concave. First 27 and second 29 optical paths are drawn in Figures 2A and 2B. A light beam is redirected, in particular internally reflected, inside the optically transmissive body 15. Optionally, the optical device 1 comprises two or more optically transmissive bodies. For example, a first optically transmissive body at the proximal end, and a second optically transmissive body at the distal end of the optical device being spaced from the first optically transmissive body. A space between the first and second optically transmissive bodies may be empty, and/or be provided with reflective optical elements for redirecting the light beam along an optical axis 25 extending between the proximal and distal end. Similar to Figure 2A, the first scanning plane 6 and the second scanning plane 8 coincide.

Figures 3A and 3B show the distal end 19 of the optically transmissive body 15, wherein the distal curved surface 23 is convex (Fig. 3A) or concave (Fig. 3B). First 27 and second 29 optical paths are drawn to indicate the paths the light beam can follow. With a concave distal curved surface 23, the distal focal point 35 is effectively located within the optically transmissive body 15. This allows for positioning of the distal end 19 of the optically transmissive body 15 closer to the plate body with respect to a convex distal surface 23, without the risk of providing the focal point beyond the plate body.

Figure 4 shows an embodiment of a system for bending a plate body, wherein the system comprises a angle measuring device and a bending punch 39. The angle measuring device comprises a sensor arrangement that includes a light source 37 for transmitting the light beam 7 towards a directing means 9. The directing means 9 comprises a rotatable mirror 11 rotatable around a rotation axis 13 for directing the light beam in to a multitude of direction within a first scanning plane 6. The angle measuring device further comprises an optical device for guiding, in use, the light beam after the direction means in a direction further away from the directing means 9. The optical device is arranged to direct the light beam at the distal end into a multitude of directions within a second scanning plane 8. In this example, the first and second scanning planes coincide. The bending punch 39 comprises a cavity 41 in which the optical device 15 is provided. For clarity, part of the bending punch 39 is shown transparent in Figure 4 to show the optical device 15 being provided in the cavity 41 of the bending punch 39. The cavity 41 extends from a proximal of the punch 39 end proximate the directing means to a distal end opposite the proximal end, and opens at the proximal and distal ends for allowing the light beam to enter and exit the optical device 15. At the distal end of the bending punch, near a working edge 43 of the bending punch 39, the cavity opens laterally, i.e. transverse to the working edge 43. The working edge 43 of the bending punch 39 which is arranged for contacting the plate body during bending thereof, can as such be uninterrupted along the length of the working edge, for evenly distributing and transferring a bending force over the length of the working edge 43 to the plate body. A protective material may be provided between the optical device 15 and the bending punch to prevent damage of the optical device. The optical device 15 may be clamped between two bending punch parts, and/or can be attached to the bending punch, for example glued, welded, or otherwise adhered. The sensor arrangement, which includes the light source 37, the directing means 9, a detector (not shown) and a processing unit (not shown), may be provided in a housing, and is provided at the proximal side of the punch 39.

Figure 5 shows an embodiment of a system for bending a plate body, comprising a angle measuring device and a bending punch 39. The bending 39 punch is the same bending punch as shown in Figure 4, and is provided with a cavity 41 for receiving therein at least a part of an optical device 15, such as an optically transmissive body, of the angle measuring device. For clarity, part of the bending punch 39 in Figure 5 is made transparent to show the optical device 15 being provided in the cavity 41 of the bending punch 39. The cavity 41 extends from a proximal end of the punch 39 proximate the directing means to a distal end opposite the proximal end, and opens at the proximal and distal ends for allowing the light beam to enter and exit the optical device 15. At the distal end of the bending punch, near a working edge 43 of the bending punch 39, the cavity opens laterally, i.e. transverse to the working edge 43. working edge 43 The angle measuring device comprises a sensor arrangement that includes a hght source 37 for transmitting the light beam 7 towards a directing means 9. The directing means 9 comprises a rotatable mirror 11 rotatable around a rotation axis 13. The angle measuring device further comprises an optical device 15 for guiding, in use, the hght beam after the direction means in a direction further away from the directing means 9. Compared to the embodiment of Figure 4, the rotating mirror 11 is displaced in a direction of the rotation axis 13, transverse to a plane in which the cavity 41 of the bending punch 39 extends. The optical device 15, in Figure 5 an optically transmissive body, is arranged to shape the optical path of the light beam in a direction transverse to a first scanning plane of the rotating mirror. The optically transmissive body refracting and/or a reflects the light beam (and a reflection thereof off the first or second plate member), out of the scanning plane in a direction transverse to the first scanning plane. At the distal end of the optically transmissive body, the hght beam is directed into a multitude of directions within a second scanning plane. The second scanning plane is in this example offset from the first scanning plane. Thereto, in this example, the optical device includes a first reflection surface 44 and a second reflection surface 45. It will be appreciated that it is also possible that the optical device includes one or more than two reflection surfaces. Thus it is e.g. possible to arrange the second scanning plane at an angle relative to the first scanning plane of the rotating mirror. It is for instance possible to arrange the second scanning plane substantially perpendicular relative to the first scanning plane of the rotating mirror.

Claims

1. Angle measuring device for measuring an enclosed angle between a first and second plate member, comprising a sensor arrangement, wherein the sensor arrangement comprises: a light source for transmitting a light beam; a directing means for directing the light beam in a multitude of directions; a detector configured for detecting a reflection of the light beam off the first or second plate member when, in use, an optical path is formed between the hght source and the detector via the directing means and by means of a reflection on the first or second plate member; and a processing unit arranged for receiving direction signals from the direction means and detection signals from the detector for determining the enclosed angle, wherein the direction signals comprise information about the direction in which the hght beam is directed by the directing means; characterised in that the angle measuring device further comprises an optical device configured for shaping a section of the optical path between the directing means and the plate members.

2. Device according to claim 1, characterised in that an optical axis of the optical device extends between a proximal end proximate the sensor arrangement and a distal end of the optical device opposite the proximal end, wherein in a direction transverse to the optical axis of the optical device, a cross section of the optical device is smaller than a cross section of a housing of the sensor arrangement in the same direction as the cross section of the optical device,.

3. Device according to claim 2, characterised in that the optical device comprises optical means for refracting and/or a reflecting the hght beam and/or, in use, a reflection thereof off the first or second plate member, in a direction substantially along the optical axis.

4. Device according to claim 2 or 3, characterised in that the optical axis is substantially curved.

5. Device according to any claims 2-4 , characterised in that the optical device comprises an optically transmissive body for refracting and/or a reflecting the light beam and/or, in use, a reflection thereof off the first or second plate member, in a direction substantially along the optical axis.

6. Device according to claim 5, characterised in that the optically transmissive body extends in axial direction of the optical axis between the distal end and the proximal end, wherein the optically transmissive body is substantially elongated in the axial direction.

7. Device according claim 5 or 6, characterised in that the optically transmissive body comprises a proximal curved surface at the proximal end facing the directing means.

8. Device according to any of claims 5-7, characterised in that the optically transmissive body has a distal curved surface for, in use, facing the plate members.

9. Device according to claim 7, wherein the proximal curved surface is convex, and wherein the proximal curved surface and the directing means are spaced a distance apart corresponding to a focal length of the optically transmissive body.

10. Device according to claim 8 or 9, characterised in that the distal curved surface is convex or concave.

11. Device according to any of claims 5-10, characterised in that a lateral cross sectional area substantially transverse to the axial direction of the optically transmissive body is substantially rectangular.

12. Device according to claim 11, characterised in that a first width of the cross sectional area is substantially smaller than a second width of the cross sectional area.

13. Device according to any of the preceding claims, characterised in that the directing means is arranged for directing the light beam in a multitude of directions within a first scanning plane.

14. Device according to claim 13, characterised in that the optical device is arranged for directing at the distal end the light beam in a multitude of directions within a second scanning plane different from the first scanning plane.

15. Device according to any of the preceding claims, characterised in that the angle measuring device is arranged to detect, with the detector, a reflection of the light beam off the first or second plate member when, in use, a transmission section of the optical path from the directing means to the first or second plate member substantially overlaps with a reflection section of the optical path from the first or second plate member to the directing means.

16. Device according to any of the preceding claims, characterised in that the light source is configured for transmitting a collimated fight beam, for example a laser beam.

17. Device according to any of the preceding claims, further comprising a bending means for bending a plate body.

18. Device according to claim 17, characterised in that the bending means comprise a bending punch extending between a proximal end and a distal end, wherein the bending punch comprises a cavity arranged for holding the optical device of the angle measuring device, wherein the cavity opens at the proximal and distal end of the punch for allowing the light beam to enter and exit the optical device.

19. Device according to claim 18, characterised in that, at the distal end of the punch, the cavity opens at two opposing lateral sides for, in use, allowing the fight beam to be submitted to the first and second plate member and for allowing the reflection of the light beam to enter the optical device at the distal end of the punch.

20. Device according to claim 18 or 19 and claim 13, characterised in that the cavity extends in the first scanning plane wherein the first scanning plane is oriented transverse to a punch edge of the bending punch, wherein the directing means are arranged to direct the light beam in a multitude of directions within said first scanning plane.

21. Device according to any of claims 18-20 and claim 14, characterised in that the cavity extends in the second scanning plane wherein the second scanning plane is oriented transverse to a punch edge of the bending punch, wherein the optical device is arranged to at the distal end direct the light beam in a multitude of directions within said second scanning plane.

22. System for bending a plate body, the system comprising a bending punch extending between a proximal end and a distal end, for bending a plate body, and an angle measuring device in accordance with any of claims 1-15, the system being configured for inline measuring of a bending angle between a first and second member of the plate like body.

23. System according to claim 22, characterised in that the bending punch comprises a cavity arranged for holding the optical device of the angle measurement device, wherein the cavity opens at the proximal and distal end of the bending punch for allowing the hght beam to enter and exit the optical device.

24. System according to claim 23, characterised in that, at the distal end of the bending punch, the cavity opens at two opposing lateral sides for, in use, allowing the light beam to be submitted to the first and second plate member and for allowing the reflection of the light beam to enter the optical device at the distal end of the bending punch.