JP2727241B2 - Work positioning device and method for press brake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a work positioning device for a press brake system that can reliably position a work at an accurate position when bending a work with a press brake. About the method.

[Related Art] When performing a bending process on a work by a press brake, it is necessary to surely position the work at an accurate position in order to perform the bending process with high accuracy.

Here, as a method of positioning the work, there is a method performed manually by an operator. That is, the work is inserted between the die and the punch until the side to be bent comes into contact with the backstop so that the longitudinal direction of the die is parallel to the side to be bent of the work. In this case, the insertion is performed by pressing the thumbs of both hands against the side opposite to the side to be bent to increase the positioning accuracy by pressing with a constant force. (Thumb).

In addition, there is an apparatus that automatically positions a work.
That is, as shown in FIG. 5, potentiometers 20 are respectively provided on both sides of two back stops of the press brake. Then, a work is inserted between the die and the punch by a press brake robot provided near the press brake. In this case, the accurate positioning position of the work is set as a predetermined value of the two potentiometers 20. Therefore, the insertion is performed by controlling the press brake robot so that the outputs of the two potentiometers 20 become the above-mentioned predetermined values.

In the press brake, the process of changing the insertion portion (side) of the work with respect to the press brake is sequentially repeated, and bending is performed to complete a product such as a box. There is a so-called lateral bending operation in which a side of a work gripped by a robot hand and a side of a work to be contacted by a backstop (a side to be bent) are orthogonal to each other.

[Problems to be solved by the invention]

However, the positioning of the work manually performed by the operator requires complicated and delicate force control from the start of the insertion of the work to the contact of the backstop. Therefore, if the same force control is to be performed by a press brake robot in order to automate the positioning operation, it will be difficult in terms of technology and cost.

Further, although the positioning of the work based on the output of the potentiometer described above can certainly achieve the automation of the positioning operation, the following problems arise.

First, since it is necessary to control the press brake robot while checking whether the output of the potentiometer has reached a predetermined value, it takes time for positioning.

Further, the higher the positioning accuracy is, the longer it takes time.

It is also necessary to adjust the potentiometer from time to time.

In addition, the potentiometer is an analog circuit, and the output is unstable and high precision cannot be expected. Therefore, it is conceivable to use an encoder instead of the potentiometer, but this causes an increase in cost and is not desirable.

Therefore, the present inventors have proposed a technique for directly hitting a work to a backstop by changing a work gripping force of a press brake robot in two stages without using a potentiometer, and the effectiveness thereof is being studied.

However, the position of the work gripped by the hand of the press brake robot is not fixed due to dimensional errors of the work, gripping errors of the work, NC errors of the robot, and the like. Therefore, when the work is inserted such that the work comes into contact with the back stop closer to the side of the work held by the hand first of the two back stops during the lateral bending operation as shown in FIG. (The arrow N indicates the insertion direction). When the work is inserted and the work comes into contact with the backstop, the work gripping force is such that the work is easily pushed back in accordance with the contact of the backstop. Then, the side closer to the hand among the bent sides of the work first is pushed by the back stop 21b. Then, a counterclockwise moment acts on the work, and the side farthest from the hand among the sides to be bent does not finally come into contact with the other backstop 21a, but with respect to the line connecting the tip surfaces of the two backstops. As a result, inaccurate positioning is performed in which the bent side of the work is not parallel and is inclined at a predetermined angle.

The present invention has been made in view of such circumstances, and can accurately and reliably position a work without incurring a decrease in work efficiency and an increase in cost, thereby enabling accurate bending. It is a first object of the present invention to provide a work positioning device and method for a press brake system. A second object of the present invention is to provide a work positioning device and method for a press brake system capable of accurately and reliably positioning a work when a lateral bending operation is performed and thereby performing accurate bending. The purpose is.

[Means and actions for solving the problem]

Therefore, in the device according to the first invention of the present invention, the insertion position of the work is regulated by two back stops,
A press brake body that performs bending of the work with a die and a punch, and the work is gripped by a hand, and the gripped work is inserted between the die and the punch until the gripped work comes into contact with the backstop. In a press brake system having a press brake robot for positioning the work, two sensors that detect that the work has contacted the backstop for each backstop, At the time of insertion, the gripping force of the hand is increased until the workpiece gripped by the hand is positioned on the die, and the gripping of the hand is started from the time when the workpiece gripped by the hand is positioned on the die. Grip force variable control means for weakening the force, and detection signals from the two sensors Once output, and means for outputting a positioning completion signal, and to perform bending of the workpiece in response to the positioning completion signal.

Further, in the method according to the first invention, the step of increasing the gripping force of the hand until the work gripped by the hand of the press brake robot is positioned on the die; A process of weakening the gripping force of the hand from the time of being positioned above, and a process of detecting that the work has contacted both the two backstops and, after this detection, a process of starting bending the work. Is executed.

That is, the gripping force of the hand of the press brake robot is strong until the work gripped by the hand is positioned on the die. For this reason, at the time of handling while swinging the work, the work is firmly gripped without shifting from the hand by a sufficient gripping force. Thereafter, the work is inserted until the work comes into contact with the two backstops. In this case, the work comes into contact with the backstop of the work due to the dimensional error of the work, the gripping error of the work, and the NC error of the robot. There is no guarantee that the power side and the line segment connecting the ends of the two backstops are parallel.

Therefore, after the work held by the hand is positioned on the die, it is no longer necessary to swing the work, so the gripping force of the hand is reduced. Then, when the work comes into contact with the backstop (one of the backstops), the reaction force of the backstop becomes larger than the frictional force of the hand, and the work is pushed back. It abuts against the backstop and ensures accurate positioning. Thus, the bending of the work is started when the work comes into contact with both of the two back stops.

Further, in the device according to the second aspect of the present invention, a press brake body for restricting a work insertion position by two back stops and bending the work by a die and a punch, and holding the work by a hand. And a press brake robot for positioning the workpiece by inserting the gripped workpiece between the die and the punch until the gripped workpiece abuts on the backstop. In a press brake system in which a side and a side of the work to be abutted by the backstop perform a lateral bending operation, two sides for detecting that the work abuts the backstop are provided for each backstop. At the time of inserting the workpiece by the sensor and the press brake robot,
Until the work gripped by the hand is positioned on the die, while increasing the gripping force of the hand,
A gripping force variable control unit that weakens the gripping force of the hand from a point in time when the workpiece gripped by the hand is positioned on the die; Press brake robot control means for inserting the work obliquely between the die and the punch so that the work comes into contact with the backstop first; and when detection signals are output from the two sensors, positioning is completed. Means for outputting a signal, and the workpiece is bent in response to the positioning completion signal.

Further, in the method according to the second invention, a step of increasing the gripping force of the hand until the work gripped by the hand of the press brake robot is positioned on the die; and A step of weakening the gripping force of the hand from the time when it is located on the die,
Detecting that the workpiece abuts on both of the two backstops, and after this detection, a process of starting bending of the workpiece is performed, and the workpiece is gripped by the hand among the two backstops. The work is inserted obliquely between the die and the punch such that the work comes into contact with the backstop farther from the side of the work.

That is, similarly to the first invention, the gripping force of the hand of the press brake robot changes in two stages, strong and weak, and the work can be swung by the strong gripping force. The work can finally be brought into contact with the two backstops with a weak gripping force that increases the reaction force. And 2
The work of bending the work is started when the work comes into contact with both the back stops.

Further, in the second invention, in addition to this, the work is inserted in advance so that the work first comes into contact with the back stop farthest from the side of the work gripped by the hand of the press brake robot among the two back stops. . Then, as shown in FIG. 3, the work first contacts the backstop far from the side of the work gripped by the hand. Here, a counterclockwise moment acts on the work, and the work then abuts against a backstop closer to the side of the work held by the hand. That is, even during the lateral bending operation, the workpiece always comes into contact with the two backstops, and accurate positioning is surely performed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an external view of an embodiment of a work positioning device and method of a press brake system according to the present invention.

As shown in FIG. 1, in this press brake system, a fixed table 2 supporting a die 1 on an upper part, and a punch 4 for bending a work (plate material) 3 by approaching the die 1 are supported on a lower part. A press brake main body 6 having a movable table 5 for raising and lowering the punch 4 so that the punch 4 can approach and lower the main body 1 is configured as a center. In addition, in the same figure, it is arrange | positioned inside the press brake main body 6, and
The two backstops 7 that regulate the insertion position of the plate material 3 inserted between the die 1 and the punch 4 (the left backstop 7a when viewed from the front, and the right backstop 7b when viewed from the front) are viewed from the die. 1. The central part of the punch 4 is omitted. The two backstops 7 are provided with conduction sensors for conducting current between the plate 3 and the backstop 7 in accordance with the contact of the plate 3 with respect to each of the backstops 7a and 7b.

The press brake system includes a plurality of plate members 3 stacked on a work mounting table in addition to the press brake body 6.
-Sheet pick-up device 8 for picking up sheets one by one by suction pad
During the handling operation by the press brake robot 9 and the press brake robot 9, which grips the plate material 3 taken out by the single-sheet take-off device 8 and supplies the gripped plate material 3 to the press brake main body 6 through a series of handling described later. When the plate material 3 is changed, the holding table 10 on which the plate material 3 is temporarily mounted, and the unloading table 11 on which the bent plate material 3 (completed product). And data corresponding to the content of bending (bending conditions, etc.) for driving the press brake main body 6, the single-sheet pick-up device 8, and the press brake robot 9 are provided in the press brake main body 6. It comprises an NC device 12 and a robot controller 13 to which input data of the NC device 12 is transferred and drives and controls the press brake robot 9.

Here, the configuration of the press brake robot 9 will be described. As shown in the figure, a skeleton 14 which is largely disposed on the floor, and an arm which is disposed above the skeleton 14 and has three joints. 15 and a hand 16 supported indirectly at the tip of the arm 15.

As shown in FIG. 2, the hand unit 16 is movable in the direction of arrow A with the indirect rotation of the arm unit 15,
The hand 16 is rotatable in the direction of arrow B by a required rotating mechanism. Two opposite rectangular fingers 17 and 18 are provided at the tip of the hand portion 16. Among these fingers 17, 18, finger 17 is a movable finger, and finger 18 is a fixed finger that is not movable. That is, the finger 17 is movable in the direction of arrow C or D by the movable mechanism,
When the finger 17 moves in the direction of arrow C, the finger 17 comes into contact with the finger 18, and when the finger 17 moves in the direction of arrow D, the finger 17 comes to be separated from the finger 18. Therefore, each movable part (the movable mechanism part and the like) of the press brake robot 9 is a robot controller 13.
As a result, the plate material 3 taken out by the single-sheet pick-up device 8 is sandwiched between the fingers 17 and 18 to hold the plate material 3, and the plate material 3 is temporarily held on the table 10. A series of handling operations of placing the plate material 3 and sequentially changing the hand gripping position of the plate material 3 so that each side of the plate material 3 is sequentially bent by the press brake body 6, and The operation of placing the bent plate material 3 (finished product) on the carry-out stand 11 can be repeated.

Here, the movable mechanism of the finger 17 is operated according to the air pressure generated by a pneumatic mechanism (not shown),
The air pressure generated by the air pressure mechanism can be set in two stages, strong and weak. For this reason, the plate material 3 is sandwiched between the fingers 17 and 18 by setting the air pressure generated in the pneumatic mechanism by the robot controller 13 at two levels, high and low, so that the gripping force when gripping is increased. , And two levels of weakness.

The handling operation is basically bent in the order of the right side 3a (short side), the left side 3b (short side), the tip side 3c (long side), and the near side 3d (long side) of the plate member 3 as viewed from the hand portion 16. Gripping position by finger 17 and finger 18 (side)
(See FIG. 2 (a)). For example, when bending the front end 3c of the plate material 3, the side (front side 3d) opposite to the side to be bent (front end 3c).
, The plate 3 is moved in the direction of the arrow E with respect to the press brake body 6 and inserted between the die 1 and the punch 4. When the front side 3d of the plate 3 is bent, the side to be bent (front side 3d) and the gripping position (tip side 3c) are opposed to each other. Will do.

When the right side 3a of the plate 3 is bent, a so-called side bending operation is performed in which the bent side (the right side 3a) and the gripping position (the front side 3d) are perpendicular to each other (see FIG. 3, G is the press brake body 6). Indicates the insertion direction with respect to. In addition,
When the left side 3b of the plate 3 is bent, the side bending operation is also performed.

Hereinafter, a control mode in the case where the distal end side 3c and the near side 3d of the plate 3 are bent will be described with reference to the case where the distal end 3c of the plate 3 is bent. Further, a control mode during the lateral bending operation will be described with reference to a case where the right side 3a of the plate 3 is bent.

First, a process of bending the front end 3c of the plate 3 will be described.

Step 101: Control for strongly gripping the plate material When the previous process, that is, the bending process of the left side 3b of the plate material 3 is completed and the process of bending the distal end side 3c of the plate material 3 is started, first, the robot controller 13 Each of the movable parts (the movable mechanism and the like) of the press brake robot 9 is drive-controlled so as to grip the side (the front side 3d) opposite to the side to be bent (the front side 3c). In this case, it is necessary to swing the plate 3 in order to bring the plate 3 from the inside of the press brake body 6 to the insertion start position after the previous step is completed. Therefore, the robot controller 13 controls so that a strong air pressure is generated in the pneumatic mechanism from the end of the previous process. Then, the movable mechanism operates and the plate 3
Is sandwiched between the finger 17 and the finger 18 with a strong gripping force. This strong gripping force is set to such an extent that the plate 3 is not displaced from the hand unit 16 during handling of swinging the plate 3.

Thereafter, the robot controller 13 controls the joints of the arm 15 and the rotating mechanism of the hand 16 as necessary, and holds the plate 3 with the hand 16 as shown in FIG. As shown in the direction of arrow E with respect to the press brake body 6, the plate 3 is placed on the die 1 so that the side of the front end 3 c of the plate 3 and the line connecting the two ends of the two backstops 7 are parallel to each other. And the punch 4 are moved.

Step 102: Control for weakly holding the plate material In the meantime, when the side to be bent of the plate material 3 (the tip side 3) is positioned on the die 1, that is, when the plate material 3 is placed on the die 1 (see FIG. 2 (a)) In), the robot controller 13 controls the air pressure mechanism to generate a weak air pressure. Then, the plate 3 is sandwiched between the fingers 17 and 18 with a weak gripping force.
It is assumed that the weak gripping force is set to be weak enough that the reaction force by the backstop 7 becomes larger than the frictional force of the hand unit 16.

Then, the robot controller 13 controls the joints of the arm 15 and the rotating mechanism of the hand 16 as needed, and subsequently holds the plate 3 with the hand 16 as shown in FIG. Pressing the plate 3 in the state
Is moved in the direction of arrow E so that the front end 3c of the plate 3 is brought into contact with the backstop 7.

In this case, the plate 3 comes into contact with the backstop 7. In this case, due to a dimensional error of the plate 3, a gripping error of the plate 3, an NC error of the robot 9, and the like, the plate 3 contacts the backstop 7. There is no guarantee that the side to be in contact (tip side 3c) and the line segment connecting the tips of the two backstops 7 are parallel. For this reason, the plate material 3 comes into contact with one backstop, for example, 7a (rarely, both backstops 7). In this case, since the gripping force is weak, the plate material 3 is brought into contact with the backstop 7a (one backstop 7). ), The reaction force of the contacted backstop 7a becomes larger than the frictional force of the hand portion 16, and the plate 3 is pushed back. Therefore, the side of the plate 3 that should contact the backstop 7 ( Tip side
3c) and the line segment connecting the ends of the two backstops 7 become parallel, and finally, the plate 3 always comes into contact with the other backstop 7b, so that accurate positioning is ensured.

Step 103: Execution of bending As described above, the sensors for detecting whether or not the plate material 3 has contacted the two backstops 7 are the respective backstops 7a and 7b.
It is attached to each. That is, when the plate member 3 comes into contact with the backstops 7a and 7b, the current I ₁ ,
I ₂ is in a conductive sensor to conduct. A signal indicating that the positioning of the plate 3 has been completed is output when both currents I ₁ and I ₂ are conducted.

When the positioning completion signal is output, the sequence control of the bending process is executed as described below.

First, the NC device 12 outputs a command to the press brake body 6 to lower the punch 4 to the shift back position. In response to this command, the punch 4 is lowered to the shift back position.

When the shift back position is detected, a detection signal is output, and in response to this detection signal, the robot controller 13 opens the hand unit 16 (the finger 17
(The moving mechanism of the finger 17). Further, in response to the detection signal, the NC device 12 outputs a drive signal for driving the movable table 5 so as to lower the movable table 5. In response to the drive signal, the hydraulic mechanism of the movable table 5 operates, and the punch 4 descends as shown by the arrow K in FIG. 2 (b), and the punch 4 and the die 1 perform bending of the plate material 3. The plate 3 jumps up with this bending, but since the hand portion 16 is in the open state, the operation can be performed so as to follow the jump of the plate 3.

Eventually, when the bending is completed, a pressure completion signal is output. Then, in response to the pressurization completion signal, the robot controller 13 drives the press brake robot 9 (movable mechanism of the finger 17) to close the hand unit 16 (moves the finger 17 in the direction of arrow D). Control.
The robot controller 13 further controls the hydraulic mechanism to generate a strong hydraulic pressure. As described above, the gripping force becomes strong from the end of the current process (the bending process on the front side 3c), and the process is shifted to the next process (the bending process on the front side 3d), and the holding of the plate material 3 is performed. The bending is performed in the same control manner as described above.

 Next, a control mode during the lateral bending operation will be described.

That is, if the bending process of the right side 3a of the plate 3 is started, the processing of the steps 101 to 103 is basically executed.
When inserting the backstop in advance, the backstop farthest from the side (front side 3d) of the plate 3 gripped by the hand unit 16 of the press brake robot 9 among the two backstops 7 in advance
The plate 3 is inserted as shown by an arrow G in FIG. 3 so that the plate 3 comes into contact with 7a first. At the time of this insertion, the robot controller 13 moves the side of the plate 3 that is bent (the tip side).
3a) controls each joint and the like of the arm unit 15 so as to form a predetermined angle θ with respect to a line segment connecting the front ends of both backstops 7. Note that the predetermined angle θ is desirably about 1 degree. Here, the position of the plate 3 gripped by the hand unit 16 is not fixed because of a dimensional error of the plate 3, a grip error of the plate 3, an NC error of the press brake robot 9, and the like. Therefore, during the lateral bending operation, as shown in FIG. 4, the back stop closer to the side of the plate material 3 gripped by the hand portion 16 as shown in FIG.
There is a case where the plate material 3 is gripped so that the plate material 3 comes into contact with 21b first.

Therefore, taking into account such errors, control is performed to insert the plate 3 so that the plate 3 first comes into contact with the backstop 7a far from the side of the plate 3 gripped by the hand unit 16. To be When the plate 3 is gripped, a control for gripping a position where such an inclination is obtained is performed, and the subsequent insertion is performed under normal control (the longitudinal direction of the finger 17 of the hand unit 16 and the longitudinal direction of the die 1). Is also possible.).

When the plate material 3 comes into contact with the backstop 7a, the gripping force is reduced as described above.
The force is such that the plate 3 is easily pushed back in response to the contact of 7a. Then, the side (3e) that is farthest from the hand portion 16 among the folded sides of the plate 3 first is the backstop 7a
Pushed by. Then, a counterclockwise moment as shown by the arrow M acts on the above 3e, and the side (3g) near the hand portion 16 of the folded side finally comes into contact with the other backstop 7b, and finally 2 The bent side 3c of the plate member 3 is parallel to a line segment connecting the end faces of the two backstops 7, and accurate positioning is performed.

Then, the same processing as in the above step 103 is performed, and the side 3a of the plate material 3 is accurately bent.

As described above, the plate member 3 surely comes into contact with the two backstops 7 and accurate positioning is performed.
Even if the plate 3 is placed on the die 1 and then the plate 3 is inserted a sufficient distance to contact the two backstops 7, the plate 3 may not eventually contact the two backstops 7.

Therefore, if the sufficient distance is set as a threshold value and the positioning completion signal is not output even if the moving distance of the plate material 3 after placing the plate material 3 on the die 1 exceeds this threshold value, an alarm indicating that an abnormality has occurred. A signal may be output. In this case, a lamp, a buzzer, or the like is operated in response to the alarm signal to notify an operator of an abnormality or execute a predetermined abnormality process.

〔The invention's effect〕

As described above, according to the present invention, it is possible to accurately and reliably position a work without causing a decrease in work efficiency and an increase in cost as compared with a conventional one, thereby performing accurate bending. Will be able to

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a work positioning device and method of a press brake system according to the present invention, and FIG. 2 (a) shows a plate material on a die by the press brake robot shown in FIG. FIG. 3B is a side view showing a state in which a plate material is inserted between the die and the punch by the press brake robot, and FIG. FIGS. 4 and 5 are views used to explain a conventional technique, and FIGS. 4 and 5 are views used to explain a conventional control technique. FIG. FIG. 5 is a perspective view showing how the work is positioned using a potentiometer. 1 ... Punch, 4 ... Die, 6 ... Press brake body, 9 ...
Press brake robot, 16… Hand unit, 12… NC device,
13 ... Robot controller.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-110018 (JP, A) JP-A-62-16819 (JP, A) JP-A-59-227379 (JP, A)

Claims (4)

(57) [Claims] 1. A press brake body for restricting the insertion position of a work by two back stops and bending the work by a die and a punch, and holding the work by a hand to hold the held work. In a press brake system having a press brake robot that positions the work by inserting between the die and the punch until the work comes into contact with the back stop, Two sensors that are detected for each back stop, and at the time of inserting the work by the press brake robot, while increasing the gripping force of the hand until the work gripped by the hand is positioned on the die, From the time when the work held by the hand is positioned on the die, And a means for outputting a positioning completion signal when a detection signal is output from the two sensors, and bending the work in accordance with the positioning completion signal. Work positioning device for press brake system. 2. A press brake body for controlling the insertion position of a work by two back stops and bending the work by a die and a punch, and holding the work by a hand, and In a work positioning method of a press brake system having a press brake robot for positioning the work by inserting between the die and the punch until the back stop abuts, the work held by the hand is A step of increasing the gripping force of the hand until it is positioned on the die; and a step of weakening the gripping force of the hand from the time when the work gripped by the hand is positioned on the die. Detecting that the workpiece abuts on both of the back stops, and after this detection, bending the workpiece. Work positioning method of press brake system having a stroke to start. 3. A press brake body for controlling the insertion position of the work by two back stops and bending the work by a die and a punch, and holding the work by a hand, and holding the held work by a hand. A press brake robot that inserts between the die and the punch to position the work until it comes into contact with the back stop, and that the back stop contacts the side of the work gripped by the hand. A press brake system for performing a lateral bending operation in which a side of the work to be performed is orthogonal to the work, wherein two sensors that detect, for each backstop, that the work has contacted the backstop, When the work is inserted, the work held by the hand is placed on the die. A gripping force variable control unit for increasing the gripping force of the hand until the workpiece is positioned, and weakening the gripping force of the hand from the time when the work gripped by the hand is positioned on the die; Press brake robot control means for obliquely inserting the work between the die and the punch so that the work comes in contact with the back stop farthest from the side gripped by the hand among the back stops, Means for outputting a positioning completion signal when a detection signal is output from the two sensors, wherein the work is bent in accordance with the positioning completion signal. 4. A press brake body for restricting the insertion position of the work by two back stops and bending the work by a die and a punch, and holding the work by a hand, A press brake robot that inserts between the die and the punch to position the work until it comes into contact with the back stop, and that the back stop contacts the side of the work gripped by the hand. In a work positioning method of a press brake system performing a lateral bending operation in which a side of the work to be performed is orthogonal to the work, a gripping force of the hand is increased until the work gripped by the hand is positioned on the die. From the time when the workpiece gripped by the hand is positioned on the die A step of weakening the gripping force of the hand, and a step of detecting that the workpiece abuts on both of the two backstops, and starting the bending of the workpiece after this detection, and The work is obliquely inserted between the die and the punch such that the work comes into contact with a backstop farther from a side of the work gripped by the hand among the two backstops. Work positioning method for press brake system.