EP2724795B1 - Assembly with a bending press and a robot and method for producing a bent component - Google Patents

Description

The invention relates to a method for producing a bent part by means of a bending press, wherein the bent part is fed by means of a gripper of a robot in the bending press and then bent by operating the bending press. Furthermore, the invention relates to an arrangement with a bending press for bending a bent part and a robot, which is prepared for feeding the bending part in the bending press by means of a gripper.

Such a method or such an arrangement are known in principle. In this case, bent parts to be bent by a robot, which is equipped with a gripper, taken from a delivery area, supplied to the bending press and bent in the connection. The bending part can be held by the robot during the bending process or can also be fixed to the bending press, for example by a tensioning mechanism. A general problem when bending a bent part are the tolerances of the blank. For example, if it is a bent part made of sheet metal, then thickness tolerances of the raw material can lead to considerable deviations of the actual bending angle from a desired set bending angle. The bent part then has to be bent over or disposed of as a waste. In any case, a re-inspection of the bent bent parts is required.

In fully automated production lines different or poorly bent bent parts can lead to significant problems in the manufacturing process, especially if not every part is controlled and poorly bent parts remain undetected. As a result, the subsequent production of the bending, in which, for example, a larger unit is assembled from several components, made difficult or even brought to a standstill. document DE 36 22 924 A1 discloses an apparatus according to the preamble of claim 1 and claim 9. It is therefore an object of the invention to provide an improved arrangement with a bending press and a robot as well as an improved method for producing a bent part. In particular, a deviation between an actual bending angle and a desired bending angle should be kept small, without the need for each bending part to be nachkontrolliert.

The object of the invention is achieved by a method according to claim 1. Furthermore, the object of the invention is achieved by an arrangement according to claim 9. In particular, the pressing pressure / the path of travel of the bending press in the above-mentioned method or in the above-mentioned arrangement is increased / shortened as the measured value for the bending thickness increases.

By determining the bending thickness before the bending process, this can be influenced to the effect that the actual bending angle approximates or even corresponds to a desired bending angle as well as possible. Bending is therefore not necessary or only in exceptional cases. Also, a follow-up of each bent part can be omitted without risking disruptions in a fully automatic production process.

Instead of the pressing pressure / the travel path or in addition to it, generally a dependent parameter of the bending press for influencing the same can be used. For example the pressing force depends on the pressing pressure. If the bending press is hydraulically driven, the amount of oil flowing into the hydraulic cylinders depends on the travel. If a spindle drive is provided, then the number of revolutions of a drive motor depends on the travel path. The stated parameters are of course only illustrative examples. Other parameters can also be used to influence the bending press.

In general, the proposed method or the proposed arrangement for the production of bent parts of all kinds, in particular for sheet metal bent parts are suitable. For this purpose, the bending press can be designed, for example, as a press bending press or as a swivel press brake. The robot can be designed as a commercial industrial robot with serially kinematic or parallel kinematic drive. Of course, this list is purely illustrative. Of course, the bending press or the robot may also have a different structure. Furthermore, it should be noted that the proposed method or the proposed arrangement is not limited to the production of bent sheet metal parts, but for example, is applicable to pipe bending machines.

Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.

It is advantageous if the bent bent part is removed with the aid of the gripper of the robot from the bending press. In this way, a fully automatic process results in the production of a bent part.

It is advantageous if the bending thickness is determined directly from the relative position of gripping elements of the gripper to each other or calculated. For example, the distance between two mutually displaceably mounted gripping elements, which corresponds to the thickness of a bending part located in the gripper, can be directly determined (measured) with a linear measuring system. It is also conceivable, however, for the thickness of a bending part in the gripper to be calculated based on the relative position of gripping elements of the gripper relative to one another. For example, the gripping elements can be rotated relative to one another and grab a pair of tongs. The angular position of the gripping elements to one another can now provide information about how thick the bending part positioned between the gripping elements.

It is advantageous if the bending thickness is determined at a predeterminable gripping force or a predetermined gripping pressure. As a result, reproducible measurement results for the bending thickness can be achieved, since the deformation of the bent part by the gripping gripper is always substantially the same. If the gripping force is so great that a falsification of the measurement result for the bending thickness is unavoidable, a (constant) correction value can also be determined in order to correct the measurement result.

But it is also advantageous if a deformation of the gripper is determined and used for a correction of the measured value for the bending thickness. In this variant, the correction value for the bending thickness is thus determined based on the currently occurring deformation. The said deformation can be determined directly, for example by means of strain gauges in the gripper, or calculated by the holding force.

It is particularly advantageous if the thickness of the bent part is determined at that gripping thereof which serves for feeding the bent part into the bending press. In this variant of the manufacturing process, a part to be bent is thus grasped, fed into the bending machine and then bent, wherein the bending thickness between the gripping of the bending part and the bending of the same is determined, without letting go of the bent part. This allows the method to be well integrated with existing systems, since the workflow with respect to the manipulation of the bent part does not change. In addition, the process presented is very efficient, since by measuring the bending thickness practically no loss of time in the production of a bent part is created. In particular, the bending thickness can also be measured during the feed movement of the robot.

Advantageously, the measurement of the bending thickness without the bending part is raised in order to avoid a falsification of the measurement result by the load on the gripping elements. For example, the gripper could be slightly widened when lifting by an arising tilting moment. Alternatively, it is also conceivable that the bent part is deposited at least on one side during measurement in order to avoid a falsification of the measurement result in this way largely.

It is also particularly advantageous if the bending thickness is determined with a handle which only serves to determine the said thickness. In this variant of the manufacturing process, a separate "measuring handle" is performed to determine the bending thickness. For example, this may be advantageous if the thickness of the bent part is to be determined at a position which differs from the position at which the bent part is lifted. Advantageously, this measurement is carried out without lifting the bending part.

It is furthermore particularly advantageous if the bending thickness is determined on or in the region of a bending line. As a result, the bending of the bent part can be carried out particularly accurately, since its thickness is determined at the position at which it is later bent. Within the scope of the invention, "in the region of the bending line" means in particular 20 cm away from the bending line, preferably 10 cm away from the bending line and more preferably 5 cm away from the bending line.

In addition, it is advantageous if the deviation of the actual angle of the bent bent part from the desired angle is determined and the influence of the bending press is adapted by the measured value of the bending thickness such that a deviation between an actual bending angle and a desired bending angle is reduced becomes. In this variant, therefore, a control circuit for the best possible achievement of the desired angle is built up. However, it is not necessary to check each bending part with regard to its actual bending angle. In principle, random measurements are sufficient to readjust the bending press initially or continuously.

• wenigstens zwei Greifelemente im Greifer, von denen wenigstens eines drehbar gelagert ist,
• einen mit dem zumindest einen drehbaren Greifelement gekoppelten Linearmotor zum Bewegen desselben,
• ein Meßsystem zum Messen einer Stellung des Linearmotors und
• Mittel zur Berechnung eines Abstands der Greifelemente, welcher die Dicke eines im Greifer befindlichen Biegeteils kennzeichnet, basierend auf der Stellung des Linearmotors. Bei dieser Ausführungsform wird wenigstens ein drehbar gelagertes Greifelement (z.B. eine Greifbacke) von einem Linearmotor bewegt. Dieser kann beispielsweise als Pneumatikzylinder, Hydraulikzylinder oder aber auch als Spindelantrieb ausgebildet sein. Durch das Drehgelenk wird die lineare Bewegung des Linearmotors in eine Dreh- beziehungsweise Schwenkbewegung des Greifelements umgewandelt, wodurch der Greifer zangenartig zupackt. Selbstverständlich kann der Greifer auch mehr als ein drehbar gelagertes Greifelement aufweisen und natürlich können die Greifelemente auch von mehr als einem Linearmotor angetrieben sein. Mit Hilfe eines Meßsystems wird die Stellung des Linearmotors ermittelt. Beispielsweise kann dazu ein handelsübliches Linearmeßsystem oder im Falle eines Spindelantriebs auch ein Winkelmeßsystem eingesetzt werden. Durch die Kopplung des Greifelements mit dem Linearmotor ist die Stellung des Greifelements abhängig von der Stellung des Linearmotors. Aus der Stellung des Linearmotors kann somit ein Abstand der Greifelemente berechnet werden, welcher die Dicke eines im Greifer befindlichen Biegeteils kennzeichnet. Durch die spezielle Bauweise kann der Greifer zudem relativ schlank gestaltet werden, sodass die Biegeteile auch bei beengten Platzverhältnissen problemlos manipuliert werden können.

Finally, it is favorable if the arrangement additionally comprises:

• at least two gripping elements in the gripper, of which at least one is rotatably mounted,
• a linear motor coupled to the at least one rotatable gripping element for moving the same,
• a measuring system for measuring a position of the linear motor and
• Means for calculating a distance of the gripping elements, which indicates the thickness of a bent part located in the gripper, based on the position of the linear motor. In this embodiment, at least one rotatably mounted gripping element (eg a gripping jaw) is moved by a linear motor. This can, for example, as a pneumatic cylinder, Hydraulic cylinder or be designed as a spindle drive. By the rotary joint, the linear movement of the linear motor is converted into a rotational or pivotal movement of the gripping element, whereby the gripper grabbing like a pair of tongs. Of course, the gripper may also have more than one rotatably mounted gripping element and of course the gripping elements can also be driven by more than one linear motor. With the help of a measuring system, the position of the linear motor is determined. For example, a commercially available linear measuring system or, in the case of a spindle drive, an angle measuring system can also be used. By the coupling of the gripping element with the linear motor, the position of the gripping element is dependent on the position of the linear motor. From the position of the linear motor can thus be calculated a distance of the gripping elements, which indicates the thickness of a bending part located in the gripper. Due to the special design, the gripper can also be made relatively slim, so that the bending parts can be easily manipulated even in confined spaces.

Fig. 1

eine schematisch dargestellte Anordnung mit einer Biegepresse und einem Roboter;

Fig. 2

einen beispielhaften Greifer des Roboters in Detailansicht und

Fig. 3

einen weiteren beispielhaften Greifer des Roboters in Detailansicht.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures. Show it:

Fig. 1

a schematically illustrated arrangement with a bending press and a robot;

Fig. 2

an exemplary gripper of the robot in detail view and

Fig. 3

another exemplary gripper of the robot in detail view.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information selected in the description, such as above, below, laterally, etc. related to the immediately described and illustrated figure and are to be transferred to a new position in a change in position.

Fig. 1 shows a schematically illustrated arrangement with a bending press 1 for bending a bending part 2 and a robot 3, which is prepared for feeding the bending part 2 in the bending press 1 by means of a gripper 40.

In this example, the robot 3 removes an unbent bent part 2 from a stack 5 and places it in the bending press 2 with the aid of its gripper 40. By activating the hydraulic pump 6 and a valve 7, respectively, the hydraulic cylinders 8 are pressurized, whereupon the blade 9 moves downwards in the direction of the die 10. By controlling the pressing pressure and / or the travel, the bending angle α can be influenced. For this purpose, the bending press 1 comprises a controller 11, which is connected to a pressure gauge 12, a linear measuring 13 and to the pump 6 and the valve 7 respectively. Thus, it is possible in a conventional manner, any arbitrary pressing force and any traverse for the sword 9 pretend / control or regulate, so as to obtain a required target bending angle as far as possible.

It should be noted that the terms "control" and "rules" are used synonymously unless otherwise specified. This means that instead of a controller, a control can be provided and vice versa, unless stated otherwise.

It is advantageous if the bending part 2 bent along the bending line 14 is removed from the bending press 1 by means of the gripper 40 as shown in this example and deposited on a stack 15 or another transport means (for example conveyor belt). In this way, a fully automatic sequence results in the production of the bending part. 2

In order to keep the deviation between the actual bending angle α and the target bending angle as small as possible even with tolerance-related variation of the thickness of the bent parts 2, the thickness of the bent part 2 is determined before bending with the aid of said gripper 40 and a Pressing pressure and / or a travel and / or a dependent parameter of the bending press 1 influenced by the measured value of the bending thickness such that a deviation between an actual bending angle α and a target bending angle is reduced.

For this purpose, the gripper 40 comprises means for determining the thickness of the bent part 2 (see in detail the Fig. 2 ), and the arrangement shown comprises means for transmitting a measured value of the bending thickness of the robot 3 to the bending press 1, specifically to the controller 11 (see dotted line). Furthermore, the controller 11 is adapted for influencing the pressing pressure and / or the travel path and / or a parameter dependent thereon of the bending press 1 by the measured value of the bending thickness such that a deviation between an actual bending angle α and a desired bending angle is reduced becomes.

Specifically, the thickness of the bending part 2 is thus determined by the gripper 40 before the bending part 2 is bent by means of the bending press 1. This reading is communicated to the controller 11 (e.g., by wire or radio), which in this example adjusts the pressing pressure and travel according to the determined bending thickness and target bending angle to be achieved. In particular, the pressing pressure is increased with increasing measured value for the bending thickness, the travel is shortened accordingly.

By said measure, a number of bending parts 2 can be produced with substantially the same actual bending angle α, even if their thickness varies. Bending is therefore not necessary or only in exceptional cases. Also, a follow-up of each bending part 2 can be omitted without risking disruptions in a fully automatic production process.

Despite the influence of the bending press 1 with the measured value of the bending thickness, it is favorable if the deviation of the actual angle α of the bent bending part 2 from the desired angle is determined and the influence of the bending press 1 is adapted by the measured value of the bending thickness such that a deviation between an actual bending angle α and a desired bending angle is reduced. In particular, the pressing pressure is increased if the actual bending angle α is too low for the bending parts 2 to be produced in the future, and the travel length is extended accordingly. As a result, the bending press 1 is continuously readjusted. In principle, rich to random samples, so that the production process is only slightly disturbed.

Fig. 2 now shows a gripper 41 in detail, although in turn in a schematic representation. The gripper 41 comprises a fixed gripping element (a fixed gripping jaw) 16 and a movable gripping element (a movable jaw) 17 which is rotatably mounted about a pivot point 18. Furthermore, the gripper 41 comprises a linear motor 19, which is coupled to the movable jaw 17 and moves it. Furthermore, the gripper 41 comprises a linear measuring system 20 for measuring a position of the linear motor 19. The rotary joint 18, the linear movement of the linear motor 19 is converted into a rotary or pivotal movement of the gripping jaw 17, whereby the gripper 41 grabbing tongs. By the coupling of the gripping jaw 17 with the linear motor 19, the position of the gripping jaw 17 is dependent on the position of the linear motor 19. From the position of the linear motor 19 can thus be calculated, the distance of the gripping jaws 16, 17, which the thickness of the located in the gripper 41 Bending parts 2 denotes or corresponds to this. Due to the special design of the gripper 41 is relatively slim, so that bending parts 2 can be easily manipulated even in confined spaces.

It is advantageous if the bending thickness is determined at a predeterminable gripping force or a specifiable gripping pressure. As a result, reproducible measurement results for the bending thickness can be achieved, since the deformation of the bending part 2 by the gripping gripper 41 and also the deformation of the gripper 41 itself is always substantially the same. It is also conceivable that the determination of the bending thickness is determined at any gripping force and from the deformations occurring a correction value for the bending thickness is determined. These deformations can be calculated, for example, or determined empirically.

If the linear motor 19 is designed as a pneumatic cylinder or hydraulic cylinder, the pressure in the cylinder can be determined. If the linear motor 19 is designed as a spindle drive, then, for example, the current consumption of the motor can be used to calculate the gripping force. In general, force sensors can also be installed in the gripper elements 16, 17 (for example, piezo pressure sensors or strain gauges) in order to be able to determine the holding forces occurring in the gripper 41.

In the illustrated gripper 41, the thickness of the bending part 2 is calculated based on the relative position of the gripping jaws 16, 17 to each other. The angular position of the gripping jaws 16, 17 to one another provides information about how thick the bending part 2 positioned between the gripping jaws 16, 17 is. It would also be conceivable that the bending thickness from the relative position of the gripping jaws 16, 17 is determined directly to each other, that is, measured. Fig. 3 shows a variant of a gripper 42, in which the gripping jaw 17 is slidably mounted. With the help of a length measuring system between the gripping jaws 16, 17, the distance between them to one another and thus the thickness of the bending part 2 located in the gripper 42 can be measured directly.

It is advantageous if the thickness of the bending part 2 is determined at that gripping thereof, which serves for feeding the bending part 2 into the bending press 1. In the present example, the bent part 2 is thus taken from the stack 5 and inserted into the bending press 1. Before bending, the bending thickness is determined in the manner previously indicated. This process is very efficient, since by measuring the bending thickness practically no loss of time during the production of a bent part 2 is formed. In particular, the bending thickness during the feeding movement of the robot 3 can be measured. Thus, the method can be well integrated into existing systems, since the workflow with respect to the manipulation of the bending part 2 does not change.

In a preferred embodiment, the measurement of the bending thickness without the bending part 2 is raised in order to avoid a falsification of the measurement result by the load on the gripping elements 16, 17. Concretely, this could be done in the present example before lifting the bending part 2 from the stack 5 or after placing it in the bending press 1. This avoids that the gripper 40..42 is widened by the tilting moment of the bent part 2 or the resulting accelerations during the manipulation and the measurement result is falsified.

Alternatively, it is also conceivable that the bent part 2 is stored unilaterally during measurement. For example, the bent part 2 in the Fig.1 rest during the measurement at its trailing edge on the stack 5 so as to at least reduce a falsification of the measurement result.

In order to further increase the accuracy of the determined measured value, the deformation of the gripper 40... 42 can furthermore be determined and used for the correction of the measured value for the bending thickness. The said deformation can be determined directly, for example by means of strain gauges, or calculated by the holding force.

In general, it is advantageous if the bending thickness is determined on or in the region of the bending line 14. As a result, the bending of the bending part 2 can be particularly accurate, since its thickness is determined at the position at which it is bent later.

Depending on the design of the robot 3, the bending press 2 or depending on the arrangement of the delivery area (stack 5) and the removal area (stack 15), it may be difficult or even impossible, the bending thickness when feeding the bending part 2 in the bending press 1 or in the area of the bending line 14 to determine. It is therefore also advantageous if the bending thickness is determined in a separate "measuring handle", which only serves to determine the said thickness. In the present example, this can be realized in that the robot 3, the bending part 2 on the stack 5 laterally engages the bending line 14 and determines the bending thickness. Thereafter, the bending part 2 is grasped at its front edge and inserted into the bending press 2. It would also be conceivable, however, for this "measuring handle" to take place after being deposited in the bending press 1. For example, the bent part 2 can in turn be packed at its front edge and inserted into the bending press 1, whereupon the robot 3 lets go of the bent part 2 and misses on its side edge. It would also be conceivable that the bending part 2 is initially only a little pushed into the bending press 1, so that access to the bending line 14 remains free. Only after measuring this is pushed into the bending position. Of course, also applies to this variant that the measurement is preferably carried out without the bending part 2 (completely) raise, or that the deformation of the bending part 2 and / or the gripper 40..42 is taken into account in determining the bending thickness.

The exemplary embodiments show possible embodiments of an arrangement according to the invention or of a gripper 40... 42 according to the invention, it being noted at this point that the invention is not restricted to the specifically illustrated embodiment variants. At this point it should be noted that in the FIGS. 2 and 3 shown grippers 40..42 are drawn purely schematically and represent only illustrative examples. Of course, a gripper can also have more than one movable gripping element and of course the gripping elements can also be driven by more than one linear motor.

Also in the Fig. 1 The arrangement shown is shown very schematically. Again, these may in reality include more or fewer components than shown.

For the sake of order, it should finally be pointed out that the components shown in the figures have been shown partly unevenly and / or enlarged and / or reduced in size for a better understanding of their structure.

The task underlying the independent inventive solutions can be taken from the description.

REFERENCE NUMBERS

1

bending press

2

flexure

3

robot

40..42

grab

5

Stack of unbent bent parts

6

pump

7

Valve

8th

hydraulic cylinders

9

bending rail

10

bending die

11

control

12

manometer

13

linear measurement

14

elastic line

15

Stack of bent bent parts

16

fixed jaw

17

movable jaw

18

swivel

19

linear motor

20

linear measurement

α

Actual bending angle

Claims (10)

1. A method for the production of a bent part (2) with the help of a press brake (1) comprising the steps:

   - feeding of the bent part (2) into the press brake (1) with the help of a gripper (40..42) of a robot (3) and

   - bending of the bent part (2) through actuation of the press brake (1),

   characterized in that

   - the thickness of the bent part (2) is determined prior to bending with the help of means (20) for determining the thickness of the bent part (2) which are comprised of the aforementioned gripper (40..42),

   - a measurement of the thickness of the bent part is transmitted from the robot (3) to the press brake (1) and

   - a forming pressure and/or a travelling distance and/or a parameter of the press brake (1) dependent thereon is influenced during bending by the measurement of the thickness of the bent part in such a manner that a deviation between the actual bending angle (α) and a desired bending angle is reduced.
2. The method according to claim 1, characterized in that the forming pressure/the travelling distance is increased/reduced as the measurement for the thickness of the bent part increases.
3. The method according to claim 1 or 2, characterized in that the thickness of the bent part is directly determined or calculated from the relative position of gripper elements (16, 17) of the gripper (40..42) relative to one another.
4. The method according to one of claims 1 to 3, characterized in that the thickness of the bent part is determined at a definable gripping force or a definable gripping pressure.
5. The method according to one of claims 1 to 4, characterized in that the thickness of the bent part (2) is determined each time it is grabbed for the feeding of said bent part (2) into the press brake (1).
6. The method according to one of claims 1 to 4, characterized in that the thickness of the bent part is determined with one grab which is used solely for determining the aforementioned thickness.
7. The method according to one of the claims 1 to 6, characterized in that the thickness of the bent part is determined on or in the region of a bending line (14).
8. The method according to one of claims 1 to 7, characterized in that the deviation of the actual angle (α) of the curved bent part (2) from the desired angle is determined and the influence of the press brake (1) is adapted by the measurement of the thickness of the bent part in such a manner that a deviation between an actual bending angle (α) and a desired bending angle is reduced.
9. An assembly comprising a press brake (1) for bending a bent part (2) and a robot (3) which is prepared for feeding the bent part (2) into the press brake (1) with the help of a gripper (40..42),
   characterized in that

   - the gripper (40..42) comprises means (20) for determining the thickness of the bent part (2),

   - the assembly comprises means for transmitting a measurement of the thickness of the bent part from the robot (3) to the press brake (1) and

   - the press brake (1) comprises a control (11) which is set up to influence a forming pressure and/or a travelling distance and/or a parameter of the press brake (1) dependent thereon during bending by the measurement of the thickness of the bent part in such a manner that a deviation between the actual bending angle (α) and a desired bending angle is reduced.
10. The arrangement according to claim 9, characterized by

    - at least two gripper elements (16, 17) in the gripper (40..42), at least one of which is mounted rotatably,

    - a linear motor (19) coupled with the at least one rotatable gripper element (17) for moving the same,

    - a measurement system (20) for measuring a position of the linear motor (19) and

    - means for calculating a distance of the gripper elements (16, 17) which characterizes the thickness of a bent part (2) located in the gripper (40..42), based on the position of the linear motor (19).

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