JP2001347320A - Method and apparatus for bending - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a time reduction by precisely position-controlling a robot gripper corresponding to a jumping up angle of a work. SOLUTION: When the work clamped by the robot gripper arranged to a robot is supplied/positioned for a bending machine and bent, successively, a bending angle is detected by a bending angle detection apparatus to detect a holding-in angle of the work in working (step S5). Based on this bending angle information, a drawing-in quantity of the work is calculated (step S7). Based on this drawing-in quantity, a bending following position of the robot is calculated, based on this calculated bending following position, a position of the robot is controlled so as to accurately follow the work. The relative position relation between the work and the robot gripper is not changed, accordingly, a time reduction is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending method and apparatus for performing a bending process using a bending machine such as a press brake using a robot capable of supplying and positioning a workpiece to a bending position.

[0002]

2. Description of the Related Art Conventionally, a bending apparatus such as a press brake 201 is provided with an upper table 203 and a lower table 205 as shown in FIG. Are mounted detachably, and a die D is detachably mounted on the upper surface of the lower table 205. Further, the press brake 201 is configured such that one of the upper and lower tables 203 and 205 is a ram that can move up and down so that the work W can be bent in cooperation with the punch P and the die D.

The press brake 201 is provided with a robot 209 capable of automatically supplying and positioning the work W to a bending position of the press brake 201 by clamping the work W with a robot gripper 207.

[0004] When bending is performed by the press brake 201, the jumping angle of the workpiece W is calculated from the bender D-axis information as the stroke position of the ram that can move up and down (the pinching angle), and based on the pinching angle. The gripper position is calculated, and the positioning of the robot gripper 207 is controlled at the calculated gripper position.

In controlling the positioning of the robot gripper 207, during bending, the robot gripper 2
07 is opened, the robot 209 follows the jump of the workpiece W, so-called “open following”, and the workpiece W is clamped by the robot gripper 207 in the final stage of bending. At the time of the above “open following”, the gripper and the workpiece W
Has a certain degree of freedom, the positional deviation between the workpiece W and the robot gripper 207 due to the jumping of the workpiece W during bending is absorbed by the above degree of freedom.

[0006] The workpiece W is a robot gripper 207.
In the case of the robot 209 that is configured to be sucked by a vacuum instead of the vacuum, the positional deviation between the workpiece W and the robot gripper 207 is absorbed by the rubber of the vacuum pad.

[0007]

By the way, in the conventional bending method and the conventional bending method, when the bounce angle (clamp angle) of the work W is calculated by the bender D axis, the material of the work W is input. For example, there is a problem that a considerable error occurs in the actual bounce angle.

Further, as described above, each time the "open following" is performed, the operation of opening the robot gripper 207, following the bending, and closing the robot gripper 207 is performed. For this reason, there is a problem that the tact time is delayed.

More specifically, referring to FIG. 17, the locus of the clamp position of the robot gripper 207 based on the flip-up angle (pinching angle) of the workpiece W calculated in advance from the bender D-axis information is ideally Although it is from point A to point A ′, it is actually point A to point B. This is because the retracted amount (= A′−B) is generated in the work W. If the retracted amount is not considered, the clamp position of the robot gripper 207 with respect to the work W is different. There is a problem that a considerable time is required for the positioning process.

[0010] In the "open following", the positional relationship between the robot gripper 207 and the work W is shifted from the initial state. Therefore, when the robot 209 approaches the work W for bending the next work W, the bending work is performed. There has been a problem that a long operation of parallelizing the line and the work W requires a long time for positioning the work W.

In addition, there is another problem that the position at which the workpiece W is clamped by the robot gripper 207 changes when the workpiece W is pulled in the direction of the mold during the bending process.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to detect a spring angle of a work, calculate a retracted amount of the work, and use the information of the retracted amount to control a robot gripper. It is an object of the present invention to provide a bending method and a bending apparatus in which time is shortened by controlling the positioning at an accurate position.

[0013]

In order to achieve the above object, a bending method according to the present invention according to the present invention is characterized in that a workpiece is supplied to a bending machine and clamped by a robot gripper provided in a robot capable of positioning. When bending a workpiece that is being bent, the clamping angle of the workpiece being bent is detected stepwise and sequentially by angle detection means, and the detected workpiece tip trajectory is calculated with respect to the calculated workpiece tip trajectory up to the target clamping angle. The retracted amount of the work at the sandwiching angle is calculated, the coordinate position of the leading end of the work to be clamped by the robot gripper at the sandwiching angle is calculated based on the calculated retracted amount, and based on the calculated coordinate position of the leading end of the work. The position of the robot gripper is controlled.

Therefore, the pinching angle and the amount of retraction of the workpiece during the bending process are sequentially calculated to calculate the coordinates of the tip end of the workpiece, so that the robot gripper and the robot gripper can accurately follow the workpiece. The relative positional relationship with the position does not change. as a result,
The robot gripper can clamp the workpiece from the start to the end of the bending process to "close following", or even if it clamps in the middle of the bending process and "close following", it can accurately and easily position the clamp Therefore, time can be reduced.

According to a second aspect of the present invention, in the bending method according to the first aspect, the workpiece being bent is clamped by a robot gripper from the start to the end of the bending. It is characterized by the following.

Therefore, the robot gripper clamps the work from the start to the end of the bending process and performs "close follow-up", so that it is not necessary to re-clamp the work, so that the time is further reduced.

According to a third aspect of the present invention, there is provided the bending method according to the first aspect, wherein the bending is performed while the workpiece is unclamped by the robot gripper from the start of the bending to the middle of the bending. , From the middle of the bending process, the angle detection means detects the pinching angle,
The position of the robot gripper is controlled based on the calculated coordinate position of the tip end of the workpiece at the sandwiching angle, and clamping is performed.

Therefore, even if the robot gripper is "open following" from the start of the bending process to the middle, it is finally clamped accurately by switching to "close following" from the middle.

According to a fourth aspect of the present invention, there is provided a bending apparatus comprising a robot gripper for clamping a work, which can be supplied and positioned freely to a bending position where the work is bent in cooperation with a punch and a die. In a bending apparatus having a robot, an angle detecting means for detecting a pinching angle of a workpiece being bent is provided, and a pinching angle detected by the angle detecting means with respect to a calculated workpiece tip trajectory up to a target pinching angle. And a second arithmetic unit that calculates a workpiece tip coordinate position at the pinching angle based on the calculated retracted amount, and a robot gripper based on the calculated workpiece tip coordinate position. A control device including a command unit for controlling the position is provided.

Therefore, the operation is the same as that of the first aspect, and since the pinching angle and the drawn-in amount of the work during the bending process are sequentially calculated and the coordinates of the position of the tip end of the work are calculated, the robot gripper can accurately detect the work. , The relative positional relationship between the work and the position of the robot gripper does not change. As a result, the robot gripper can clamp the workpiece from the start to the end of the bending process to “close following”, or accurately and easily perform the clamp positioning even if the clamp is performed during the bending process to “close following”. As a result, time can be reduced.

According to a fifth aspect of the present invention, in the bending apparatus according to the fourth aspect, the angle detecting means is provided at a plurality of positions on both inclined side surfaces of the work near both shoulders of the die groove of the die. A laser length measuring device that irradiates a laser beam from a reference position to measure a distance to a laser irradiation point,
The inclination angles of both sides of the work are calculated based on the distance from the reference position measured by the laser measuring device to the plurality of laser irradiation points, and the sandwiching angle of the work is calculated based on the calculated inclination angles. And a first arithmetic unit.

Therefore, the inclination angle of both sides of the work is calculated based on the distance from the reference position measured by the laser length measuring device to a plurality of laser irradiation points. , Which are detected by easy and successive calculations.

According to a sixth aspect of the present invention, there is provided a bending apparatus according to the present invention, wherein the angle detecting means detects a distance between blades from an upper surface of a die to a bottom dead center of a bent portion of the work. A comparison judging unit for detecting a sandwiching angle corresponding to the inter-blade distance detected by the work bottom dead center detection device from a database stored in the control device in advance.

Therefore, the clamping angle of the workpiece during the bending process is easily and sequentially detected from the database based on the distance between the blades detected by the workpiece bottom dead center detecting device.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a bending method and apparatus according to the present invention will be described below with reference to the drawings.

Referring to FIG. 2 or FIG. 3, for example, a press brake 1 as a bending apparatus according to the present embodiment includes an upright side frame 3. Is provided with an upper table 5, and a punch P is detachably mounted on an intermediate plate 7 as a punch mounting portion below the upper table 5. On the other hand, a lower table 9 is provided on a lower front surface of the side frame 3. A die D is detachably mounted on the die mounting portion on the lower table 9.

The press brake 1 is configured such that one of the upper and lower tables 5 and 9 can move up and down as a ram, and the work W is bent by cooperation of the punch P and the die D. In the present embodiment, for example, the lower table 9 is configured to move up and down by the ram cylinder 11 (see FIG. 11).

The work W is clamped to the press brake 1 by the robot gripper 13 so that the press brake 1
Robot 15 as a workpiece moving device capable of automatically supplying and positioning the workpiece W with respect to the bending line
Is provided so as to be movable on the front side of the lower table 9 in the left-right direction (X direction) in FIG. The robot 15 is provided with a robot gripper 13 capable of supplying and positioning the work W to a desired bending line with respect to a desired bending line with respect to the press brake 1 in the front-rear direction (Y direction) and the up-down direction (in FIG. , Z direction).

In this embodiment, the robot 15 is mounted on a base plate 17 which is integrally mounted on the lower table 9 which can move up and down.

More specifically, the base plate 17 extends in the X-axis direction along the longitudinal direction of the die D, and a first movable table 19 is supported on the front surface of the base plate 17 so as to be movable in the X-axis direction. . This first moving base 19 includes:
A pinion (not shown) meshed with the X-axis direction rack 21 provided on the base plate 17 is rotatably driven by a first motor 23. The first motor 2
3 is provided with a position detecting device such as an encoder, so that the moving position of the first moving base 19 in the X-axis direction can be detected.

The first movable base 19 is provided with a fan-shaped portion 25 whose upper side is enlarged in the Y-axis direction, and the upper portion of the fan-shaped portion 25 has a rear portion as shown in FIG. A rack member 27 is provided as an arcuate guide member curved so that the front side is lower than the front side. On this rack member 27, a second movable table 29 that is movable in the Y-axis direction along the rack member 27 is supported. A pinion meshed with the rack member 27 is rotatably driven by the second motor 31 on the second movable table 29. In addition,
Since the second motor 31 is provided with a position detecting device such as an encoder like the first motor 23,
The moving position of the moving table 29 in the X-axis direction can be detected.

The second moving table 29 supports a vertically movable column 33 that is movable in the vertical Z-axis direction perpendicular to the moving direction of the second moving table 29. A vertical rack is formed on the lifting column 33, and a pinion meshed with the rack is rotatably driven by a third motor 35. Since the third motor 35 is provided with a position detecting device such as an encoder like the first motor 23, the lifting column 33 is moved up and down by the drive of the third motor 35, and the up and down movement position is It is detected by the position detecting device.

When the second moving table 29 is moved forward along the rack member 27, the lifting column 33 is inclined forward and moves up and down diagonally. Function so as to be separated from each other.

An arm 37 extending in the Y-axis direction is appropriately fixed on the upper part of the lifting column 33. A robot gripper 13 that can freely grip one side edge of the work W is attached to the tip of the arm 37.

More specifically, the robot gripper 13
It is provided so as to be rotatable in the vertical direction about a B axis parallel to the axis, and is freely rotatable about an A axis orthogonal to the B axis. Further, a fourth motor 39 for rotating the robot gripper 13 about the A-axis is used.
A fifth motor 41 for rotating the robot gripper 13 up and down about the B axis is mounted on the arm 37. The above-described fourth and fifth motors 39 and 41 correspond to FIG.
As shown in FIG. 1, it is connected to a control device to be described later, and has a position detecting device such as an encoder like the first motor 23 described above.

An upper jaw 43 for clamping and unclamping the workpiece W is provided on the robot gripper 13.
And a lower jaw 45 are provided. Since the upper and lower jaws 43 and 45 are rotatably supported by a rotating sleeve (not shown) that is rotatable around the B axis, the work W clamped by the upper jaw 43 and the lower jaw 45.
For example, as shown in FIG. 3, is turned around a large angle range that is reversed around the B axis.

As shown in FIG. 4, the press brake 1 has, for example, a butting device 47 as a work positioning device for positioning the work W to be moved while being gripped by the robot gripper 13 of the robot 15. Is provided. In this embodiment, the abutting device 47 includes two X-axis abutting portions 49 for positioning the workpiece W in the X-axis direction, and one Y-axis abutting portion 51 for positioning the workpiece W in the Y-axis direction. , Is composed of.

More specifically, the X-axis abutment portion 49 is formed of the Y-axis guide rail 5 having the X-axis abutment portion main body 53 extended leftward and forward (Y direction) in FIG.
5 and a rack 57 and a pinion (not shown) parallel to the Y-axis guide rail 55 and an X-axis abutting portion motor 59 are provided so as to be movable and positioned in the Y direction. . The X-axis abutment section motor 59 has a position detecting device such as an encoder.

An X-axis cylinder 61 provided with a piston rod that expands and contracts in the X-axis direction is provided on the X-axis butting portion main body 53, and the tip of the piston rod functions as the X-axis butting portion 49. . An X-axis abutment sensor 63 for detecting contact of the workpiece W is mounted at the tip of the X-axis abutment portion 49.

The Y-axis butting portion 51 is provided in the Y-axis butting portion main body 6.
A rack 5 is movable in the X-direction along an X-axis guide rail 67 extending in the left-right direction (X-direction) behind the lower table 9 and is parallel to the X-axis guide rail 67.
9, a pinion (not shown), and a Y-axis abutting portion motor 71 are provided so as to be movable and positionable in the X direction. The Y-axis striking portion motor 71 includes a position detecting device such as an encoder, like the X-axis striking portion motor 59 described above.

A Y-axis cylinder 73 having a piston rod that expands and contracts in the Y-axis direction is provided in the Y-axis butting portion main body 65, and the tip of the piston rod functions as the Y-axis butting portion 51. . Note that a Y-axis abutment sensor 75 for detecting the abutment of the work W is attached to the tip of the Y-axis abutment portion 51.

Accordingly, the workpiece W to be bent is moved and positioned by the robot 15 so as to be abutted against the two X-axis abutments 49 and the one Y-axis abutment 51 of the abutment device 47. . At this time, X
The detection of the shaft abutment sensor 63 and the Y-axis abutment sensor 75 detects that the edge of the workpiece W has been abutted and positioned.

On the left side of the left side frame 3 in FIG. 2, a control device 77 for controlling the robot 15, the robot gripper 13, the butting device 47, the ram cylinder 11, and the like is provided.

Referring to FIG. 11, the control unit 77 includes a CPU 79 as a central processing unit.
An input device 81 such as a keyboard as input means for inputting various data and a display device 83 such as a CRT for displaying various data are connected to the U79.

The CPU 79 has a development view, three views,
First memory 8 in which data such as a bending length, a bending angle, and a flange length are input from input device 81 and stored as bending processing information of work W obtained from a three-dimensional view or the like.
5 is connected.

Further, based on the mold layout information, the information of the robot gripper 13, the gripper reference plane information, and the gripper moving distance, the CPU 79 sends the robot gripper 13
For example, a main control unit 87 is connected as a command unit for giving a command for moving and positioning the press brake 1 to a predetermined die mounting position to a robot axis control unit described later.

A mode changeover switch 89 for switching the robot gripper 13 to a follow-up mode in which the robot gripper 13 follows the jump of the workpiece W is connected to the CPU 79 via a main control section 87.
Lower table 9 which is a movable table while watching the screen of 3
A manual pulsar 91 for adjusting the stroke of the motor is connected via a main controller 87.

The CPU 79 is connected to a robot axis controller 93 for controlling each axis of the robot 15.
The first motor 23, the second motor 31, the third motor 35, the fourth motor 3
9, the fifth motor 41 and each encoder are connected.

Further, the CPU 79 includes a butting device 47.
Abutting device axis control unit 95 for controlling each axis is connected.
The shaft abutting portion motor 59, the Y-axis abutting portion motor 71, and each encoder are connected.
1 and the X-axis butting sensor 63, and the Y-axis cylinder 73 and the Y-axis butting sensor 75 are also connected.

Next, a bending angle detecting device 97 as an angle detecting means according to the present embodiment will be described with reference to the drawings.

As shown in FIGS. 5 and 6, a plurality of slits 99 are formed at appropriate positions in the left and right direction of the die D so as to communicate with the die groove DV. A hole may be used instead of the slit 99. As shown in FIG. 6, a reflection mirror 101 which is inclined obliquely upward by approximately 45 ° and constitutes a reflection surface is provided in the slit 99. On the back surface of the lower table 9, an X-axis motor 103 is provided.
A support bracket 109 is provided which is movable in the X-axis direction, in the L-axis direction which is the same direction as the Y-axis direction by the L-axis motor 105, and in the Z-axis direction by the Z-axis motor 107. A vessel 111 is provided. Note that each X-axis motor 103 and L-axis motor 10
5. The Z-axis motor 107 is provided with an encoder (not shown) as a position detector.

With the above configuration, the laser length measuring device 111
It is moved in the axial direction, the L-axis direction, and the Z-axis direction and is positioned at a desired position. Moreover, the laser beam LB illuminated from the laser length measuring device 111 is reflected by the reflection mirror 10.
After being reflected at 1, the light is irradiated to the side surface of the work W through the slit 99. The irradiated laser beam LB is returned to the laser length measuring device 111 as return light, and the laser length measuring device 111
From the work W to the side surface of the workpiece W is detected. Note that the reference position, which is the tip position of the laser length measuring device 111 in the L-axis direction, is previously positioned at a desired position by the L-axis motor 105.

Further, the laser length measuring device 111 is connected to the Z-axis motor 1.
A plurality of distances to both side surfaces of the work W are detected by moving and positioning by 07. Therefore, the bending angle of the work W is accurately calculated using the detected distance to the both sides of the work W.

Referring again to FIG. 11, the CPU 79 of the control device 77 is connected to a distance memory 113 for inputting and storing the distance to the side surface of the work W detected by the laser length measuring device 111.

The CPU 79 includes a laser length measuring device 11.
A first calculation device 115 for calculating a bending angle based on the distance to the side surface of the work W detected in 1 is connected.

The CPU 79 is connected to a BI axis controller 117 for controlling each axis of the bending angle detector 97 (BI; abbreviated as Bending Indicator). The BI axis controller 117 described above is connected to the CPU 79 via the BI axis controller 117. The X-axis motor 103, the L-axis motor 105, the Z-axis motor 107, and each encoder are connected.

The algorithm for calculating the bending angle will be described. Referring to FIG.
Is provided with, for example, one light emitting device 119 and a light receiving device 121. The optical axes 1 and 2 of the laser light LB illuminated from the one light emitting device 119 are reflected by the reflection mirror 101 to form the work W In FIG. 7, the light is irradiated on the right side of the work W.
Thereafter, the light is received by the light receiver 121 as return light. The laser measuring device 111 is moved and positioned upward in the Z-axis direction as shown by the two-dot chain line, and irradiates the laser beam LB with the optical axes 3 and 4 in the manner described above, thereby obtaining a diagram of the workpiece W. At 7 irradiates the left side. Thereafter, the light is received by the light receiver 121 as return light. Therefore, the distances to the four sides of the work W are detected.

That is, the moving amount of Z ₁ → Z ₂ at that time is l ₁ and the moving amount of Z ₃ → Z ₄ is l ₂ . Further, the movement amount of Z ₂ → Z ₃ is L.

When the bending angle θ is calculated based on the detected distance with reference to FIG. 8, the following is obtained.

[0060] In the optical axis 1 and the optical axis _{2, l '1 = l 1 /} cosα 1 ...... (1) l 12 = (l' 1/2) × [1 / cos (90-α 1)] = _{(l 1/2) × {} 1 / cosα 1 × cos (90-α 1)} If the difference between ... (2) measurement length is ^{_{a 1, α 2 = tan -1}} (a 1 / l 1) α ₃ = cos ⁻¹ (l ₁ / l ₁₂ ) = cos ⁻¹ (2 cos α ₁
× cos (90−α ₁ )), and θ ₁ = 90− (α ₂ + α ₃ ) θ ₁ = 90− ｛tan ⁻¹ (a ₁ / l ₁ ) + cos ⁻¹ (2 cos α ₁ × cos (90−α) _1))} (3) in the optical axis 3 and the optical axis _{4, l '2 = l 2} / cosα 1 ...... (4) l 22 = (l' 2/2) × [1 / cos (90 -α _1)] = _{(the l 2/2) × {1} / cosα 1 × cos (90-α 1)} ...... (5) the difference between the measured length is ^{_{a 2, α 4 = tan -1}} (a ₂ / l ₂ ) α ₅ = cos ⁻¹ (l ₂ / l ₂₂ ) = cos ⁻¹ ( ₂ cos α ₁
× cos (90−α ₁ )), and θ ₂ = 90− (α ₄ −α ₅ ) θ ₂ = 90− ｛tan ⁻¹ (a ₂ / l ₂ ) −cos ⁻¹ ( ₂ cos α ₁ × cos (90 −α ₁ ))｝ (6) Therefore, θ = θ ₁ + θ ₂ = 180− ｛tan ⁻¹ (a ₁ / l ₁ ) + tan
⁻¹ (a ₂ / l ₂ )}.

Next, the work bottom dead center detecting device 123 constituting the angle detecting means according to the present embodiment will be described with reference to the drawings.

Referring to FIG. 9, a plurality of displacement meters 125 are provided inside the die D in the longitudinal direction of the die D.
In this displacement meter 125, a detection pin 129 which is always urged upward by a spring 127 and protrudes from the V-groove of the die D and protrudes from the material when it moves up and down is provided. Is provided below the spring 127.

Therefore, the work W pressed and bent by the punch P pushes the detection pin 129 downward, and the vertical position of the detection pin 129 at this time is detected by the linear scale 131, and as shown in FIG. Detection pin 12
The distance between the upper end of the die 9 and the upper surface of the die D is obtained as the inter-blade distance ST.

Referring again to FIG. 11, the CPU 79 of the control device 77 stores a database file storing a database based on a graph showing the relationship between the bending angle and the inter-blade distance as shown in FIG. 133, a data correcting unit 135 for correcting the database, a comparison determining unit 137 for comparing the measured angle of the bending angle of the bent workpiece W with the target angle, and controlling the ram cylinder 11 to reduce the stroke of the punch P. A stroke command unit 139 to be controlled is connected. Further, a displacement meter 125 is connected, and a detection signal is transmitted.

With the above configuration, the blade-to-blade angle at a desired bending angle (here, 90 °) can be obtained by a graph or a calculation formula showing the relationship between the bending angle and the blade-to-blade distance stored in the database. The distance ST1 is obtained. That is, in the graph and the calculation formula showing the relationship between the bending angle and the blade-to-blade distance ST1, the springback amount is calculated and considered in advance from the finish angle, which is the actual bending angle, and the work conditions for each work W in advance. Since the entrapment angle is shown, the entrapment angle can be determined by detecting the inter-blade distance ST1.

Referring again to FIG. 11, the CPU 79 of the control device 77 includes the bending angle detecting device 9 described above.
7, the retracted amount of the work W is calculated based on the clamping angle of the work W calculated by the work bottom dead center position detection device 123, and the leading end coordinates of the work W, in other words, the clamp position by the gripper, is calculated from the retracted amount. A second arithmetic unit 141 for calculating coordinates is connected.

The CPU 79 calculates the amount of movement for moving the bender axis by performing pulse distribution on the D axis based on the calculated value of the D value, and calculates the coordinate of the tip of the work calculated by the second arithmetic unit 141. A pulse distribution amount calculation device 143 is connected to calculate a movement amount for performing pulse distribution to each axis of the robot 15 based on the calculated value and moving the robot 15 to follow the axis.

Next, a bending method according to the present invention will be described with reference to FIG.

As die data, die V width V, die shoulder radius DR, die groove angle DA, punch tip radius PR, punch angle PA, punch inclination length PL, work thickness t, friction coefficient μ, work flange Bending conditions such as length L and finishing angle θ are input from the input device 81 and stored in the first memory 85. (Step S1).

The mode changeover switch 89 is turned on to switch to the following mode. The work W is in the state of “closed follow-up” in which the robot gripper 13 follows the jump of the work W at the time of bending while the work W remains clamped by the robot gripper 13 (step S2).

The lower table 9 is driven by the operator with the manual pulsar 91, or the target enclosing angle θ '
Is input and the lower table 9 is automatically driven (step S3).

The sandwiching angle θ of the work W is measured.
That is, the sandwiching angle θ is calculated based on the data obtained by the bending angle detection device 97 or the work bottom dead center detection device 123. The measurement of the sandwiching angle θ is sequentially performed during the bending until reaching the target sandwiching angle θ ′ (Steps S5 and S6).

If the measured clamping angle θ has not reached the target clamping angle θ ′, the remaining angle to be bent is calculated from the difference between the measured clamping angle θ and the target clamping angle θ ′. An angle obtained by dividing the remaining angle in a stepwise manner, and a D value for this angle;
Robot TCP (Teaching Point) to be clamped by the tip coordinate of the work, that is, the robot gripper
The coordinates are calculated.

For example, the arc-shaped trajectory of the edge of the work W up to the target sandwiching angle θ ′ without considering the amount of work drawn in can be calculated by a simple calculation as shown in FIG. Is required.

On the other hand, the angle difference from the measured sandwiching angle θ to the target sandwiching angle θ ′ is divided stepwise into θ1, θ2, θ3,..., Θi as shown in FIG. The tip value (xi, y) of the workpiece when the stroke value (D value) of the D axis at the angles θ1, θ2, θ3,.
i) is calculated.

For example, each of the sandwiching angles θ1, θ2, θ3,
.., L1 and L drawn in by the workpiece W corresponding to θi
2, L3,..., And Li are represented by plastic theory f (V, DR, D
A, PR, PA, PL, X, μ, n, F) using the second arithmetic unit 141. In this case, the n value and the F value are input in advance from the input device 81 and stored in the first memory 85 as material constants.

Therefore, when the drawn-in amount is L1 when the sandwiching angle is θ1, the workpiece tip coordinates (x1, y) are obtained from the difference between the calculated locus and the drawn-in amount L1.
1) is calculated as the robot TCP coordinates. The D value at this time is also calculated as D1.

Similarly, when the retraction amount is L2 when the sandwiching angle is θ2, the coordinates of the workpiece tip (x
2, y2) is calculated as the robot TCP coordinates, and the D value is calculated as D2.

When the retraction amount is L3 when the sandwiching angle is θ3, the coordinates of the workpiece tip (x3, y3) are calculated as robot TCP coordinates, and the D value is calculated as D3.

As described above, based on the difference between the measured entrapment angle and the target entrapment angle, the retraction amount corresponding to the entrapment angle that is driven in stepwise and bent is calculated, and the calculated entrainment amount is calculated. The robot TCP coordinates and the D value are calculated on the basis of (Steps S7 and S7).
8).

The calculated values D1 and D of the calculated D values
Pulse distribution is performed on the D axis based on 2, D3,..., Di, and the vendor axis (D axis) moves (steps S9 and S9).
10).

The calculated values (x1, y1), (x2, y2), (x1, y2) of the workpiece tip coordinates calculated in step S7 above.
3, y3),..., (X1, y1)
5 is distributed to each axis of the robot gripper 13.
Of the robot 15 to follow the coordinates of the tip of the workpiece
The robot axes such as the axes, the A axis, and the B axis move (steps S11 and S12).

When the above-described steps S5 to S12 are repeated and the measured sandwiching angle θ reaches the target sandwiching angle θ ′, the mode changeover switch 89 is turned off and the following mode is switched off (step S13).

The lower table 9 is lowered, and the punch P and the die D are separated from each other (step S15).

As described above, the clamping angle and the amount of retraction of the workpiece W during the processing are sequentially calculated, and the coordinates of the workpiece tip position (the clamp position of the robot gripper 13) are calculated. Therefore, the relative positional relationship between the workpiece W and the position of the robot gripper 13 does not change.

In the above-described embodiment, as shown in FIG. 14, the robot W follows the work W clamped by the robot gripper 13 during the period from the start to the end of the bending, so-called “closed”. However, in another embodiment, as shown in FIG. 15, from the start of bending to the end of bending, as shown in FIG. 15, the robot gripper 1 in step S4 in the flowchart of FIG.
3 may be performed in a so-called “open follow-up” mode in which the workpiece W follows the uplift of the workpiece W in an unclamped state. In this case, for example, the work W is set in step S1.
4 is clamped by the robot gripper 13.

As one method in this case, just before the end of the bending process, as described above, the drawing-in amount of the work W is calculated based on the clamping angle data obtained in real time by the bending angle detecting device 97 as described above. Thereby, the coordinates of the workpiece tip are calculated, and the robot gripper 13 follows and clamps the workpiece W based on the coordinates of the workpiece tip. After that, “close follow-up” is performed until the bending process is completed, and follow-up follows the workpiece tip coordinates calculated based on the sandwiching angle data obtained by the bending angle detecting device 97 in real time.

In this case, as another method, the work bottom dead center detecting device 12 is provided just before the end of the bending as described above.
3 is used to calculate the measured sandwiching angle θ from the data of the D value obtained in real time.
The coordinates of the leading end of the work are calculated by calculating the amount of pull-in of the work W based on the above data, and the robot gripper 13 follows and clamps the work W based on the leading end coordinates of the work. After that, “close follow-up” is performed until the bending process is completed, and follow-up follows the workpiece tip coordinates calculated based on the sandwiching angle data obtained by the bending angle detecting device 97 in real time.

The present invention is not limited to the above-described embodiment, but can be embodied in other forms by making appropriate changes.

[0090]

As will be understood from the above description of the embodiments of the present invention, according to the first aspect of the present invention,
Since the position of the workpiece tip position can be calculated by calculating the pinching angle and the amount of work drawn in during bending, the robot gripper can accurately follow the workpiece. Since the relative positional relationship between the work and the position of the robot gripper does not change, the robot gripper can clamp and follow the work from the start to the end of the bending process, or can clamp and close the work during the bending process. Even if "following" is performed, accurate and easy clamp positioning can be performed, so that time can be reduced.

According to the second aspect of the present invention, the robot gripper clamps the work from the start to the end of the bending process and performs "close follow-up", so that it is not necessary to re-clamp the work, so that the time can be further reduced. it can.

According to the third aspect of the present invention, even if the robot gripper performs "open follow-up" from the beginning of the bending process to the middle, it can finally clamp accurately by switching to "close follow-up" from the middle.

According to the fourth aspect of the present invention, the same effect as in the first aspect can be obtained, and the pinching angle and the amount of retraction of the work during bending can be sequentially calculated to calculate the coordinates of the work tip position. The robot gripper can accurately follow the workpiece. Since the relative positional relationship between the work and the position of the robot gripper does not change, the robot gripper can clamp and follow the work from the start to the end of the bending process, or can clamp and close the work during the bending process. Even if "following" is performed, accurate and easy clamp positioning can be performed, so that time can be reduced.

According to the fifth aspect of the present invention, since the inclination angles of both sides of the work are calculated based on the distance from the reference position measured by the laser measuring device to the plurality of laser irradiation points, the bending process is performed. It is possible to easily and sequentially calculate and detect the sandwiching angle of the workpiece in the middle.

According to the sixth aspect of the present invention, the clamping angle of the workpiece during bending can be sequentially and easily detected from the database based on the distance between the blades detected by the workpiece bottom dead center detecting device.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a flowchart of a bending method.

FIG. 2 is a front view of a press brake as a bending device used in the embodiment of the present invention.

FIG. 3 is a side view of a press brake as a bending device used in the embodiment of the present invention.

FIG. 4 is a schematic perspective view of the butting device according to the embodiment of the present invention.

FIG. 5 is a front view of a die according to the embodiment of the present invention.

FIG. 6 is a schematic side view of the bending angle detecting device according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram for detecting a bending angle by a bending angle detection device.

FIG. 8 is an explanatory diagram for detecting a bending angle by a bending angle detection device.

FIG. 9 is a cross-sectional view showing a displacement meter of the work bottom dead center detection device according to the embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a distance between blades in the work bottom dead center detection device.

FIG. 11 is a configuration block diagram of a control device.

FIG. 12 is a graph showing a relationship between an angle and a distance between blades.

FIG. 13 is a state explanatory view showing a relationship between a sandwiching angle and a retracted amount during bending.

FIG. 14 is an explanatory diagram illustrating a state of “close following” of the robot gripper during bending.

FIG. 15 is an explanatory diagram illustrating a state in which the robot gripper switches from “open following” to “close following” during bending.

FIG. 16 is an explanatory diagram of a state of “open following” by a conventional press brake robot.

FIG. 17 is an explanatory diagram of a state of “open following” by a conventional press brake robot.

[Explanation of symbols]

 Reference Signs List 1 press brake (bending machine) 5 upper table 9 lower table 13 robot gripper 15 robot 77 control device 85 first memory 87 main control unit (command unit) 89 mode changeover switch 93 robot axis control unit 97 bending angle detection device 111 laser Length measuring device 113 Distance memory 115 First computing device 117 BI axis control unit 123 Work bottom dead center detecting device 141 Second computing device

Claims (6)

[Claims] When a workpiece clamped by a robot gripper provided in a robot capable of supplying and positioning a workpiece to a bending machine is bent, a clamping angle of the workpiece during the bending is gradually changed. Sequentially, the angle is detected by the angle detecting means, the retraction amount of the workpiece at the detected entrapment angle is calculated with respect to the calculated workpiece tip trajectory up to the target entrapment angle, and based on the calculated entrainment amount, A bending method comprising: calculating a coordinate position of a tip of a work to be clamped by a robot gripper at a sandwiching angle; and controlling the position of the robot gripper based on the calculated coordinate position of the work tip. 2. The bending method according to claim 1, wherein the workpiece being bent is clamped by a robot gripper from the start to the end of the bending. 3. A process in which the workpiece is unclamped by a robot gripper from the start of the bending process to the middle of the bending process so as to follow the bending. 2. The bending method according to claim 1, wherein the position of the robot gripper is controlled and clamped based on the calculated coordinates of the tip end of the workpiece. 4. A bending apparatus comprising a robot gripper for clamping a work, and a robot capable of supplying and positioning a work to a bending position for bending the work in cooperation with a punch and a die. An angle detecting means for detecting a sandwiching angle of a workpiece in the middle is provided, and a work retracted amount at a sandwiching angle detected by the angle detecting means is calculated with respect to a calculated work tip trajectory up to a target sandwiching angle; A second arithmetic unit for calculating a workpiece tip coordinate position at the sandwiching angle based on the calculated retracted amount; and a command unit for controlling the position of the robot gripper based on the calculated workpiece tip coordinate position. A bending device comprising a control device. 5. The angle detecting means irradiates a laser beam from a reference position to a plurality of positions on both inclined side surfaces of a work near both shoulders of a die groove of a die to measure a distance to a laser irradiation point. Calculates the inclination angles of both sides of the work based on the distance from the laser measuring device and the reference position measured by the laser measuring device to a plurality of laser irradiation points, and calculates the work based on each calculated inclination angle. 5. A first computing device for computing a sandwiching angle of the first and second components.
The bending apparatus described in the above. 6. A work bottom dead center detection device for detecting a distance between blades from an upper surface of a die to a bottom dead center of a bent portion of a work, and the angle detection means includes: 5. The bending apparatus according to claim 4, further comprising: a comparison judging unit that detects a sandwiching angle corresponding to the inter-blade distance detected by the work bottom dead center detection device.