JPH0547766B2 - - Google Patents

Description

Detailed Description of the Invention The present invention optically projects the end face of the V-shaped bent part of the target workpiece, and installs a photoelectric sensor for photoelectric detection on the image plane to determine the press angle of the target workpiece. This invention relates to a press work angle detection method that automatically measures the angle of press work.

When a workpiece 4 made of a metal plate is placed on a mold of a press brake pedestal 2, and the workpiece 4 is pressed by a pressure table to set the angle of the workpiece 4 as shown in FIG. The angle of the workpiece 4 changes slightly depending on the pressure of the pressure table 6. Once the workpiece 4 is removed from the pedestal 2 in the press brake, it cannot be pressed again. Further, the angle of the workpiece 4 located between the receiving table 2 and the pressurizing table 6 cannot be measured with a measuring tool because the tables 2 and 6 get in the way. Therefore, conventionally, after the workpiece 4 is pressed, it is removed from the tables 2 and 6, and the press angle of the workpiece is measured using a separately provided measuring tool, and when the angle is larger than a predetermined value, Readjust to increase the pressure on the workpiece 4. In this case, a large number of defective products will be produced before the workpiece 4 is set at a predetermined angle.

In order to solve the above problems,
In this publication, a bending angle measuring device has been developed which projects an image of the workpiece onto a slide plate with a scale and reads the bending angle of the workpiece visually by an operator.

Since the above-mentioned device reads the workpiece angle by visual inspection by the operator, there is a possibility that the device may read the workpiece angle incorrectly. Furthermore, since the position of the workpiece is not constant during angle measurement, it is necessary to perform adjustment work to match the reference point of the workpiece and the reference point of the scale, which is cumbersome.

A first object of the present invention is to automatically detect the bending angle of a press work using a photoelectric sensor without removing the press work from between a pressure table and a cradle of a press brake.

When attempting to automatically detect the press work angle using a photoelectric sensor, a configuration is adopted in which four end points of the edge of the press work are detected, and the angle of the press work is detected from the four end points of the edge. It is possible to do so. In this case, if a protrusion is formed on the edge of the press work, the end point of the protrusion will be detected as the end point of the edge of the press work, resulting in a large error in detecting the angle of the press work. The problem arises that the

Another object of the present invention is to reduce errors in detecting the angle of a press work even if a protrusion is formed on the edge of the press work.

The configuration of the present invention will be described in detail below based on embodiments shown in the accompanying drawings.

In FIGS. 2 to 4, reference numeral 10 denotes a base, on which a mounting plate 12 is erected.

An arm is fixed to the base 10, and a lighting fixture 14 is attached to the arm so that its angle can be adjusted.
A tubular holder 16 is fixed to the mounting plate 12, and a cylinder 18 is rotatably fitted into the holder 16. The cylindrical body 18 is fixed to the holder 16 with screws. The cylindrical body 18 includes an internal cylindrical body 20
are slidably fitted into each other, and a casing 22 is fixed to the front end of the cylindrical body 20. Casing 2
A guide 24 is fitted and fixed in the opening of 2, and a threaded part formed on the inner diameter of the guide 24 is threaded with a threaded part shaped on the outer diameter of the holder that holds the lens 26. There is. 28 is a screw fixed to the guide 24, on which a bevel gear 30 is rotatably supported, a filter holder 32 is fixed to the bevel gear 30, and a colored filter 34,
36 are installed vertically. The filter 34 is colored green, and the filter 36 is colored red.
A shaft 38 is rotatably supported by the mounting plate 12, and a rope pulley 40 is fixed to one end of the shaft, and a pipe 42 is fixed to the other end. 44 is a cylindrical body that is slidably fitted to the inner peripheral surface of the pipe 42, and one end of the shaft body 46 is fixed to this.
The other end of the shaft body 46 is rotatably supported by the casing 22. A long groove is formed in the pipe 42 along its longitudinal direction, and a pin fixed to the cylindrical body 44 is slidably disposed in the long groove. An intermediate portion of the shaft body 46 is rotatably supported by a bracket 48 fixed to the casing 22. A bevel gear 50 is fixed to the shaft body 46, and the bevel gear 50 meshes with the bevel gear 30. 52 is a pulse motor fixed to the mounting plate 12, and an endless rope is stretched between a rope pulley fixed to the output shaft of the pulse motor and the rope pulley 40. 54 is the internal cylinder body 2
0, and a heat insulating filter 56 is fixed to this holder.

58 is a tube body rotatably supported on the mounting plate 12, on which a shaft body 60 is rotatably arranged;
A lever 62 is fixed to one end of the shaft body 60, and a member 64 is fixed to the other end. The member 64 includes a screen 6 made of a glass plate for checking focus.
6 is fixed. A lever 67 is fixed to one end of the tubular body 58, and a glass screen 68 for checking focus is fixed to the other end via a member. Reference numerals 70 and 72 designate sensor holding members whose upper ends are rotatably supported by shafts 74a and 76a on the mounting plate 12. Photoelectric line sensors 74, 76, 78, and 80 are attached to the sensor holding members 70 and 72, respectively. Photoelectric line sensor 74, 7
6, 78, and 80 are commercially available line sensors in this embodiment. The line sensor has a large number of minute light detection elements arranged directly above it.
The photoelectric line sensor is located within a through hole formed in the mounting plate 12. Holes 82 and 84 are transparently provided in the lower portions of the sensor holding members 70 and 72, and are positioned on the lines of rotation about the axes 74a and 76a of the holes 82 and 84, and are mounted on the mounting plate 12 at a predetermined pitch. An index hole 86 consisting of a stepped screw hole is provided transparently. Adjacent to the holes 82, 84, holes 88, 90 are transparently provided in the holding members 70, 72 so as to be located on the alignment line of the index holes 82 for finely adjusting the angle of the members. Reference numerals 92 and 94 indicate limit switches having a stopper function, which are attached to the casing 22. The limit switches 92 and 94 are connected to a controller (not shown) that drives the pulse motor 52.

Figure 6 shows the central processing unit CPU of this device.
100 is a pulse oscillator, 102, 104, 10
A timing control circuit 6,108 generates timing for driving the photoelectric sensor.
Drivers 110, 112, 114, and 116 convert timing signals generated by the timing control circuit to a level capable of driving the photoelectric line sensor. 118, 120, 122, 124 are amplifier circuits, and photoelectric line sensors 74, 76,
The output signals from 78 and 80 are differentially amplified. 12
Slice level setting circuits 6, 128, 130, and 132 slice the analog signal at a constant level and convert it into a digital signal. 134 is a counter control circuit, and oscillator 100
The range to be counted is determined by comparing the signals from the sensors 74, 76, 78, and 80 with the signals from the sensors 74, 76, 78, and 80. A counter circuit 136 counts the pulses output from the counter control circuit 134. 138 is an arithmetic circuit which calculates the center of the thickness of the workpiece 4 based on the value counted by the counter circuit 136, and at the same time outputs the photoelectric line sensors 74, 76, 78, The distance of the center from the X coordinate reference is determined from the correction value Xs on the X axis of each of the 80 reference points. A register circuit 140 stores four types of values obtained by the circuit 138 described above. 146 is an arithmetic circuit that calculates the angle A of the workpiece 4 based on the numerical value stored in the register circuit 140 and the sensor interval value from the register 148. 150 is a display, 14
2 is an angle setting input circuit, and this circuit 142 is
It has an input section into which a plurality of set displacement angle signals centered on the axes 74a and 76a from the reference positions of the sensor holding members 70 and 72 are input, and a storage section stores the plurality of set displacement angle signals. For each, the angle value of each of the photoelectric line sensors 74, 76, 78, 80 with respect to the X axis and the coordinate value Xs on the X coordinate axis of the reference point of each of the photoelectric line sensors 74, 76, 78, 80 are stored. has been done. When the displacement angle signal of the sensor holding members 70, 72 is input to the input section, the angle setting input circuit 142 selects the photoelectric line sensors 74, 7 corresponding to the displacement angle signal.
Angle value signals with respect to the X coordinate axes 6, 78, and 80 and X coordinate values Xs of each reference point of the line sensors 74, 76, 78, and 80 are output.

The angle setting input circuit 142 inputs the coordinate value Xs on one axis of the reference point of each of the photoelectric line sensors 74, 76, 78, and 80 corresponding to the amount of displacement angle from the reference position of the sensor holding members 70 and 72, and the It constitutes a means for outputting the angle value of the photoelectric line sensors 74, 76, 78, 80 with respect to the one axis.

In addition, the index hole 86, holes 82, 84
and the stepped screw 162 are connected to the sensor holding member 70,
72 constitutes an index means for releasably locking the index member 72 at predetermined angles.

Next, the operation of this embodiment will be explained.

First, the base 10 is arranged so that the lens 26 faces the press end surface of the workpiece 4 held between the pressure table 6 and the pedestal 2 of the press brake. next,
By rotating the levers 67, 62, the screen 66,
68 is arranged opposite to the sensors 74, 76, 78, and 80. Next, loosen the screw 160 and
0 in its longitudinal direction and screen 6
6 and 68 are set to a desired magnification, and the screw 160 is tightened to fix the internal cylinder 20 to the cylinder 18.

In the magnification adjustment work by sliding the internal cylinder 20, the operator projects an optical image of the workpiece bent at a predetermined angle on the screens 66, 68, and a predetermined portion of the workpiece optical image is detected by the photoelectric line sensors 74, 7.
The magnification of the workpiece light image is adjusted so that the workpiece light image is irradiated with 6, 78, and 80 pixels.

Next, the holder of the lens 26 is slightly rotated to bring the image of the workpiece 4 reflected on the screens 66, 68 into focus on the detection surfaces of the photoelectric line sensors 74, 76, 78, 80. If the pressure table 6 and pedestal 2 of the press brake and the workpiece 4 are made of the same material and have the same end surfaces, the end surfaces of the workpiece 4 are painted red in accordance with the green filter 34. Thereby, the contrast between the end face of the workpiece and other parts can be increased, and the end face of the workpiece and the tables 2 and 6 can be distinguished. In addition, tables 2 and 6 and work 4
If the end face conditions of the tables 2 and 6 are different, the light images of the tables 2 and 6 and the light image of the workpiece 4 can be distinguished by the internal circuit of the central processing unit CPU, so a colored filter 34 or 36 is used.
It is not necessary to provide . Incidentally, driving the motor 52 ,
By rotating the bevel gears 50 and 30, the red filter 36 can be positioned on the optical image of the workpiece. When using the red filter 36, the end face of the workpiece is colored green. Work 4
In order to position the photoelectric line sensors 74, 76, 78, 80 on a predetermined optical image of the workpiece 4 according to the pressing angle of the
The rotation angle about 6a is determined and the shoulder screws 162 are screwed into the desired index holes 86 through holes 82, 84 or 88, 90 to secure the retaining members 70, 72 to the mounting plate 12. After setting the fixed angles of the holding members 70 and 72, the operator inputs the angle values into the input section of the circuit 142.
This angle value can be configured to be automatically input to the input section of the circuit 142 by a signal such as a switch provided for each index hole. The circuit 142 calculates the angle of each of the photoelectric line sensors 74, 76, 78, 80 with respect to the X axis and the photoelectric line sensors 74, 76, 7 based on this angle value.
The coordinate value XS on the X axis of each of the reference points 8 and 80 is output. The workpiece 4 is illuminated by the lighting fixture 14, and the optical image of the workpiece 4 is sent to the photoelectric sensors 74, 7.
6, 78, 80. At this time, the screens 66, 68 are moved above the front proximity positions of the sensors 74, 76, 78, 80 by rotating the levers 62, 67. When the measurement switch 164 is pressed, each photoelectric line sensor 74, 76, 78,
80 detection signal is counter control circuit 1
34. Now, the signal from the sensor 74 will be explained. The signal of sensor 74 is sent to circuit 126
is converted into a digital signal shown in FIG. 9C. A low level portion C of the digital signal in FIG. 9C shows a portion where the optical image of the work 4 hits the sensor 74. The counter circuit 136 is
The distance b between XS and XT is counted by the number of pulses, while the distance C between XT and XV is counted by the number of pulses. These count values b and c are calculated by the calculation circuit 1.
38, where b+(c/2)=d is calculated. The arithmetic circuit 138 calculates the above d value and the circuit 14.
2, the X-coordinate value of the center point P1 of the optical image of the workpiece 4 based on the angle value of the line sensor 74 with respect to the X-axis and the X-coordinate value XS of the reference point of the line sensor 74.
Calculate x1. By the same operation as above, the arithmetic circuit 138 calculates P2, P3, and P4 of the workpiece light image.
The X coordinate values x2, x3, x4 of the points are calculated and these values are stored in the register 140. Arithmetic circuit 14
6 is the distance l between the above x1, x2 and the sensors 74, 76
Based on, first calculate X = |x2|−|x1|,
With this, calculate Sin C1=X/l, and C1=
Calculate Sin ^-1 X/.

Using the same principle as above, point P3 with respect to the Y coordinate axis,
Calculate the angle C2 of the line segment passing through P4. With C1 above
The angle A of the workpiece 4 with C2 added is displayed on the display 150.
displayed digitally. The operator can obtain the desired pressing force of the pressurizing table 6 by increasing the pressurizing force of the pressurizing table 6 until the workpiece 4 reaches a predetermined angle while looking at the above display. This pressurizing table, that is, the amount of approach of the pressurizing table 6 to the cradle 2 is stored in a storage device. In addition, when measuring the angle of work 4,
The pressure table 6 is moved slightly away from the pedestal 2 to release the pressure on the workpiece 4. This is because the workpiece 4 has a tendency to return to its angle slightly when the pressure from the pressure table 6 is released, and this return needs to be taken into account. As shown in FIG. 8, a half mirror H is arranged between the sensor D and the lens L, a screen S is arranged above the half mirror H, and the midpoint of the half mirror H and the sensor If the distance a between D and the distance b between the screen S and the midpoint of the half mirror H are set to be the same, the image on the sensor D can be viewed with the screen S on a separate optical path. In the figure, F is a colored filter and G is a heat insulating filter.

In this embodiment, as shown in FIG. 10, a semi-fixed system using four line sensors 74, 76, 78, and 80 is adopted, but the system is not particularly limited to this system. For example, as shown in FIG. 11, an image parallel scanning method using two line sensors 170 may be employed. In this method, the angle of the workpiece is measured while moving one sensor 17 on each of the left and right sides up and down. By arranging the sensor 170 diagonally and moving it at a pitch of about 1/3 of the sensor length, the entire press area of the optical image of the workpiece can be covered. Further, FIG. 12 shows an image parallel scanning method using one line sensor 172. Figure 13 shows the line sensor 174,
This shows an image rotation scan method using a single beam. If the sensor 172 is tilted and used as a rotating scan method, it can be rotated at a pitch of 15 to 18 degrees to cover the entire press area of the workpiece light image. FIG. 14 shows a single element sensor 176,
This shows an image rotation scan method using two units. This method is a single-element version of the method shown in FIG. 13, and requires a fine scan pitch, but since the reading time for a single element is short, the overall measurement time is also more advantageous than the method shown in FIG. 12.

As described above, the present invention measures the coordinate value of the intermediate point on the predetermined coordinate axis of the optical image of the detected part of the workpiece, and calculates the angle of the workpiece based on this coordinate value. Even if a protrusion is formed on the image, there is an effect that the amount of error in the angle measurement value can be reduced.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the press brake, Figure 2 is a plan view, Figure 3 is a sectional view taken along line A-A, Figure 4 is a rear view, Figure 5 is a schematic diagram, and Figure 6 is a block circuit diagram. , Fig. 7 is an explanatory diagram, Fig. 8 is an explanatory diagram, Fig. 9 is an explanatory diagram, Fig. 10 is an explanatory diagram, Fig. 11 is an explanatory diagram,
FIG. 12 is an explanatory diagram, FIG. 13 is an explanatory diagram, and FIG. 14 is an explanatory diagram. 2... cradle, 4... workpiece, 6... pressure table, 10...
Base, 12... Mounting plate, 14... Lighting fixture, 16... Holder, 18... Cylindrical body, 26... Lens, 34, 36...
Filter, 66... Screen, 68... Screen, 70, 72... Sensor holding member, 74, 7
6, 78, 80...Photoelectric line sensor, 86... Index hole.

Claims (1)

[Claims] 1 Photoelectric line sensors can be disposed at two locations in each of both parts based on the bent part of the optical image of the workpiece bent by press work so as to cross the optical image of the workpiece in the width direction, and the photoelectric line sensor Inclination angle data of the sensor with respect to a predetermined axis in a scanning direction that crosses both parts of the workpiece optical image in the width direction; and scanning detection signals of the photoelectric line sensor that cross each of the two parts of the both parts of the workpiece optical image; calculate the midpoint in the width direction of the workpiece light image on the predetermined axis at two places on each of both parts, and scan the two places on one side of the workpiece light image in the width direction. distance data between positions, distance data on a predetermined axis between the two intermediate points of the one side part, width direction scanning distance data of two positions on the other side of both parts, and the other side. A method for detecting an angle of a press work, characterized in that the angle of a bending part of the workpiece optical image is calculated from distance data on a predetermined axis between the two intermediate points of the part.