Optics: measuring and testing – Angle measuring or angular axial alignment
Reexamination Certificate
2001-06-05
2002-11-12
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Angle measuring or angular axial alignment
Reexamination Certificate
active
06480269
ABSTRACT:
BACKGROUND TECHNOLOGY
FIG. 13
shows one example structure from the prior art for detecting the bending angle 2&thgr; of a measurement object comprised of a workpiece W which has undergone a bending process in cooperation with a punch P and a die D equipped in a press brake (omitted from the drawings), wherein an upward bend angle 2&thgr; is determined by raising or lowering a detection element
101
to bring the tip of the detection element
101
into contact with a lower surface of the workpiece W, with this value then being doubled to determine the bending angle 2&thgr;.
In the above-described structure of an angle detection apparatus
103
, an ascension/descension device
107
such as a cylinder is provided on a die base
105
equipped with a die D, and by means of this ascension/descension device
107
the detection element
101
is raised in an upward direction in
FIG. 13
to be brought into contact with a lower surface of the workpiece W. The raised position of the detection element at this time can be measured, for example, by a pulse encoder
113
connected to a pinion gear
111
which meshes with a rack
109
arranged to move up and down together with the detection element
101
, whereby a structure is formed for detecting the bending angle 2&thgr;.
Further, a process for detecting the bending angle of the workpiece may be carried out by imaging an edge surface of the bent up workpiece with a non-contact imaging means and then processing such imaged data with a image processing.
Furthermore, there is another angle measurement apparatus, in which a rotatable frame equipped with a light source and a converging lens is provided, and in which a plurality of light-receiving elements are arranged in the shape of a circular arc at a location corresponding to the focus position of the converging lens, whereby reflected light of the light which emitted toward the workpiece from the light source is focused by the converging lens toward the position of the light-receiving elements arranged in the shape of the circular arc, whereby the position of the light-receiving elements where the received light is a maximum is detected in order to detect the bending angle of the workpiece.
However, there is a problem with regards to these types of prior art technology in that highly accurate angle detection is difficult because the bending angle is determined from the relationship between the position of the die D and the position of the workpiece W determined by measuring the position of the detection element
101
in contact with the workpiece W.
Further, because angle detection is carried out by bringing the detection element
101
into contact with the workpiece W, deformation of the workpiece W will arise depending on the strength of contact with the detection element, and this risk of changes arising in the bending angle creates a problem.
Further, in the case where an image processing device is used, because the apparatus is a non-contact type, there is no risk of changes arising due to contact, but high costs and the ability to only measure an edge surface of the workpiece creates problems.
In the structure having a plurality of light-receiving elements arranged in a circular arc shape at positions corresponding to the focus of the rotating converging lens, because accurate measurements are difficult if the light-receiving elements are shifted even a small amount from the focus position of the converging lens, there is a need for high precision in the apparatus and this creates problems.
In view of the problems of the prior art described above, it is an object of the present invention to provide an angle detection method for bending machines, an angle detection apparatus and an angle sensor which make it possible to carry out highly accurate angle detection by detecting the angle of a bent workpiece without making contact with the surface of the workpiece.
DISCLOSURE OF THE INVENTION
In order to achieve the object stated above, in the angle detection method for bending machines according to the invention of claim
1
, detection light is emitted toward a measurement object from a light source provided in an angle sensor equipped with a plurality of optical sensors arranged at mutually opposite positions with the light source therebetween, the angle sensor is rotated in the forward and reverse directions within the plane where the light source and optical sensors are arranged, and the angle of the measurement object is detected based on the rotation angle of the angle sensor at the time when the quantity of light received by one of the optical sensors is a maximum and the rotation angle of the angle sensor at the time when the quantity of light received by the other optical sensor is a maximum.
Accordingly, detection light emitted from the light source of the rotating angle sensor impinges onto the measurement object and the reflected light therefrom is received by the plurality of optical sensors positioned on opposite sides with the light source therebetween, and the angle of the measurement object is measured from the angles of the angle sensor at the positions where the quantity of light received by each of the optical sensors forms a peak. That is, in an example structure where the optical sensors are positioned symmetrically at equal distances from the light source, the angle of the detection object can be detected from the fact that the detection light impinges onto perpendicular to the detection object at an intermediate rotation angle position of the angle sensor between the positions where the quantity of light received by each of the optical sensors is a maximum.
In the angle detection method for bending machines according to the invention of claim
2
, detection light is emitted toward a measurement object from a light source provided in an angle sensor equipped with at least one pair of optical sensors arranged at symmetrical positions with the light source centered therebetween, the angle sensor is rotated in the forward and reverse directions within the plane where the light source and optical sensors are arranged, and the angle of the measurement object is detected based on the rotation angles of the angle sensor from a reference position when the quantities of light received by the pair optical sensors are the same.
Accordingly, detection light emitted from the light source of the rotating angle sensor strikes the measurement object and the reflected light therefrom is received by the pair of optical sensors symmetrically positioned at equally distances from the light source, and the angle of the measurement object is measured from the rotation angle of the angle sensor at the time when the quantities of light received by the pair of optical sensors are the same. That is, the angle of the detection object is detected from the fact that the detection light from the light source is incident perpendicular on the detection object when the same quantity of light is received by each of the optical sensors arranged symmetrically at equal distances from the light source.
In the angle detection apparatus according to the invention of claim
3
, the apparatus includes an angle sensor equipped with a light source for emitting detection light toward a measurement object and a plurality of optical sensors for receiving reflected light from the measurement object, the optical sensors being located at mutually opposite positions with the light source arranged therebetween, and the angle sensor being rotatable in forward and reverse directions in the plane where the light source and the optical sensors are arranged; a rotation angle detector for detecting the rotation angle of the angle sensor with respect to a prescribed reference position; a peak value detection portion for detecting the peak value of the reflected light received by the optical sensors; and an angle calculation portion for calculating the angle of the measurement object based on those rotation angles of the angle sensor detected by the rotation angle detector which should correspond to the peak values detected b
Brinkman Gerben Jan
Hiraizumi Mitsuo
Amada Electronics Company, Ltd.
Nguyen Tu T.
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