EP1342514B1 - Device for detecting a ring bending angle, and method of regulating a bending machine - Google Patents

Description

The invention relates to a bending machine with a device for detecting a bending angle of a movable in a feed direction of a bending part, wherein the bending machine has bending rollers through which the bending part is transported during the bending operation in the feed direction, while the bending part in the bending machine of the action of a in a to the feed direction different bending direction acting bending tool is subjected, and a method for controlling a bending machine.

When bending tool-independent bending radii, z. Example, in three- or four-roll bending, or free-form bending or segment bending, so far occurs the problem that the bending angle of the bending part can not be measured during the bending process.

Rather, the known methods for detecting a directional angle disadvantageously allow only the bending radius after a certain rolling distance, which may be up to 600 mm long, depending on the bending geometry and the roller arrangement of the bending machine. With unknown material behavior of the workpiece to be bent thus there is a risk that the workpiece was bent after this required to determine the bending radius rolling line with a wrong bending radius and has already reached (prematurely) the desired bending angle, or that only a small rolling line remains after the detection of the bending radius can be bent with the correct radius. A precise bending of workpieces with unknown material behavior is thus not immediately possible with the known methods in a disadvantageous manner. This is particularly problematic for small bending radii whose settlement is smaller than the required for determining the bending radius test section. For this circumstance results in the known methods in a disadvantageous manner a high material consumption, since first the material behavior of the workpiece must be determined in order to then be able to bend the workpiece correctly.

Another disadvantage of the known method is that no or only a conditional reaction to disturbances during the bending process is possible.

From the DE 198 22 023 There is known a folding machine having a self-learning device by which the folding angle of an element to be folded can be measured to obtain drive data for a folding device, which then allows a plurality of folding elements to be folded by the same folding angle. For this purpose, the device for detecting the folding angle of an element to be folded on a base plate which is fixedly mounted on a support frame of the folding machine. On the base plate, a Kodierertragelement is detachably mounted. The encoder support member carries an encoder having a rotary scale transfer member for transferring the amount of folding of the item to be folded. A gripping portion of the rotary scale transmission member engages the element to be folded, and a connecting bridge connected to the gripping portion transmits the deflection of the gripping portion to a rotary shaft of the encoder. Such a device only makes it possible to obtain drive data for the folding device for subsequent folding operations of the elements to be folded, but not a detection of the folding angle during the folding process.

It is therefore an object of the present invention, a device and a method of the type mentioned in such a way that the bending angle of a bent part during the bending process, in which the bent part is advanced by the bending machine, is easily detectable.

This object is achieved in that the device has at least one angle measuring device which is arranged in the feed direction of the bending part according to the bending tool of the bending machine, that the at least one angle measuring device has a transmitter having a measuring element which can be brought into a measuring system to the bending part in that at least one angle measuring device is pivotable about an axis that is substantially orthogonal to the bending plane of the bending part, that measuring signals generated by the angle measuring device or measuring devices at the bending part can be conducted to a control and evaluation device of the bending machine. and evaluation the difference of the Angle measuring detected bending angle determined at the beginning and at the end of the bending part traversed bending section and from the ratio of the bending distance and the difference of the bending angle determines an actual settlement of the bent part and compares with a target settlement and therefrom a difference between the target settlement and actual -Abwicklung compensating change of the setting of the bending tool performs.

The inventive measures a bending machine is provided with a device for detecting the bending angle of the bending part in an advantageous manner, which is characterized in that the bending angle during the bending process continuously, quasi-continuously or at certain time intervals in a simple manner can be detected , The device according to the invention thus advantageously permits an in-process measurement of the bending angle, which ensures that deviations of the bending angle of the bending part from a predetermined nominal value can be detected directly and the bending process can be corrected accordingly.

The device according to the invention can advantageously be used as a measuring device for simple and direct detection of the relative and absolute angles of two straight lines of the workpiece lying on the same plane, wherein the measurement of the directional angle of a straight line within the measuring range of the Winkeimeßvorrichtung the straight line to be measured can be made easily and quickly. An advantage here is also that the angle between the two lines can still be measured even if the position and the direction of the two lines or the angle between these two lines changed. This allows in particular the controlled in-process measurement during bending, measurement of pre-bent bending parts having one or more arcs, the angle measurement of straight lines connected by a U-shaped structure, and the controlled bending and / or bending of the aforementioned structures.

A further advantage of the bending machine according to the invention is that when calibrating the at least one angle measuring device, the straight lines to be measured can be located at arbitrary locations within the measuring range.

Another advantage of the device according to the invention of the bending machine is that it is easy to handle, since in the device according to the invention no complicated zero balancing must be performed. Rather, it is for detecting the bending angle of the bent part in an advantageous manner only required that before the bending process, the two transducers of the two bending devices are brought into contact with the straight, so not bent part and the present then the position of the two transducers as the zero Position is set.

Another advantage of the device according to the invention is that it is suitable for in-process measurement of bending angles for almost any bending radii. Therefore, the device according to the invention is characterized by its high flexibility.

An advantageous development of the invention provides that at least one of the angle measuring is arranged on a measuring arm. Such a measure has the advantage that in this way in a simple manner, the angle measuring easily slightly different curvatures of the bent part can be nachführführden so as to keep the transmitter of the angle measuring in abutment with the bending part.

A further advantageous embodiment of the invention provides that the measuring arm is designed as a joint-parallelogram, the first end is preferably attached to the bending machine and the second end carries an angle measuring. Such a measure has the advantage that in this way a particularly suitable guide element for the angle measuring device is formed in a simple manner. Another advantage of this measure is in that thereby the function of the bending machine, in particular a three- or four-roller bending machine, not limited by the device according to the invention or the inventive device is not limited in a measuring process by the structure of the bending machine in its measuring range.

A further advantageous embodiment of the invention provides that at least one angle measuring device is rotatably arranged on the bending machine. Such a configuration is used in particular for use as an inlet-side, arranged in front of the bending tool of the bending machine Winkelmeßeinrichtung, since in this area the bent part still has its straight, non-curved course.

A further advantageous embodiment of the invention provides that the transmitter of the angle measuring device is designed as a rotary encoder, on whose axis the measuring element is arranged. Such a measure has the advantage that in this way a sufficiently accurate measuring system of the transmitter to the bending part can be achieved in a simple manner.

A further advantageous embodiment of the invention provides that the measuring element arranged on the axis of rotation of the rotary encoder has a gripper unit, by means of which the measuring element can be fixed on the bent part. Such Measure has the advantage that in this way a good measuring system of the measuring element on the bent part can be achieved in a simple manner.

The inventive method for controlling a bending tool having a bending machine, in which the bending part is subjected to the action of a bending direction acting in a different bending direction to the bending direction acting bending device, according to the invention provides that by a control and evaluation of the bending machine to achieve a predetermined Bending angle and a predetermined bending radius of the bending part required target settlement of the bent part determined in the feed direction and the bending tool of the bending machine is set in its bending direction according to this target settlement that the bent part is advanced in the feed direction by a bending path and bent by the bending tool of the bending machine in that the bending distance of the bending part is detected and the difference in the bending angles at the beginning and at the end of this bending distance is determined by a device for detecting a bending angle, that from Ver Ratio of the bending distance and the difference of the bending angle an actual settlement is determined that the control and evaluation compares the target settlement with the actual settlement and from this comparison a difference between the target settlement and actual settlement compensating change in attitude of the bending tool performs.

The inventive method is particularly suitable for the inventive device for detecting a direction angle, in particular a bending angle.

Further advantageous developments of the invention are the subject of the dependent claims.

Figur 1

eine schematische Darstellung einer Biegemaschine mit einem ersten Ausführungsbeispiel einer Vorrichtung zur Erfassung des Biegewinkels eines Biegeteils,

Figur 2

eine Draufsicht auf das Ausführungsbeispiel der Figur 1,

Figur 3

eine Seitenansicht einer Ausführungsform einer Winkelmeßeinrichtung,

Figur 4

eine Draufsicht auf die Winkelmeßeinrichtung der Figur 3,

Figur 5

eine Draufsicht auf ein zweites Ausführungsbeispiel,

Figur 6

eine Seitenansicht einer zweiten Ausführungsform eines Meßelements,

Figur 7

eine Draufsicht auf die zweite Ausführungsform des Meßelements,

Figur 8

eine schematische Darstellung eines dritten Ausführungsbeispiels, und

Figur 9

eine schematische Darstellung eines vierten Ausführungsbeispiels.

Further details and advantages of the invention can be found in the embodiments, which are described below with reference to the figures. Show it:

FIG. 1

a schematic representation of a bending machine with a first embodiment of a device for detecting the bending angle of a bent part,

FIG. 2

a plan view of the embodiment of FIG. 1 .

FIG. 3

a side view of an embodiment of an angle measuring device,

FIG. 4

a plan view of the angle of the FIG. 3 .

FIG. 5

a plan view of a second embodiment,

FIG. 6

a side view of a second embodiment of a measuring element,

FIG. 7

a plan view of the second embodiment of the measuring element,

FIG. 8

a schematic representation of a third embodiment, and

FIG. 9

a schematic representation of a fourth embodiment.

In FIG. 1 Now, a bending machine 1 is shown, which comprises a bending tool 2, which in the case shown here consists of three bending rollers 2a-2c. The bending tool 2 serves to bend a bending part B in a bending direction. The bending rollers 2a-2c further cause a feed of the bending part B in a feed direction, the - like FIG. 1 it can be seen - is different from the bending direction of the bending tool 2. Such for bending the bending part B (please refer FIG. 2 ) serving bending machine 1 is known per se and therefore need not be described in detail.

At the bending machine 1 now two angle measuring 10a and 10b are arranged. For clarity, is in FIG. 1 only the outlet side arranged, second angle measuring 10b shown. The - with an assumed feed direction of the bending part B from left to right - inlet side, first angle measuring device 10a is constructed according to the second angle measuring device 10b.

Each of the two angle measuring devices 10a, 10b of the first embodiment thus has a transmitter 11, which is arranged on a measuring arm 12, which is articulated with its first end 12 'on the bending machine 1, and at its second end 12 "carries the transmitter 11 In the case shown here, the measuring arm 12 is designed as a joint parallelogram 13. This has the advantage of a particularly simple mechanical design of the measuring arm 12.

Each transmitter 11 has - in the case shown here - a rotary encoder 14 which has an axis A which is substantially orthogonal to the bending plane of the bending part B. On the axis A, a measuring element 15 is arranged. The measuring element 15 has in the case shown here, a gripper unit 16 with a U-shaped base 16 ', in its limited by the two legs 16a, 16b interior, the bending part B receivable and lockable by means of a Zustellelements 17 on the inside of the leg 16a of the base body 16 is, so as to ensure that a firm connection between the measuring element 15 and the bending part B is given.

The operation of the device for detecting the bending angle of the bending part B will now be described with reference to FIG FIG. 2 explained. This in turn shows the bending machine 1 together with the device 10 for detecting the bending angle of Bending parts B, but in FIG. 2 - As already explained above - both angle measuring devices 10a and 10b are shown.

The bending part B is now inserted into the bending machine and the first angle measuring device 10a is brought into abutment with the bending part B, so that the measuring element 15 abuts the bending part B. This is achieved in that the bending part B is inserted into the U-shaped base body 16 'of the gripper unit 16 of the measuring element 15 and the measuring element 15 is fixed in measuring system on the bending part B by the delivery element 17 is delivered. The position of the rotary encoder 14 caused thereby is now set as the zero position of the first angle measuring device 10a.

In a corresponding manner, the second angle measuring device 10b is then brought to the bending part B in the measuring system. The measuring element 15 of the rotary encoder 14 of the second angle measuring device 10b is then in measuring system on the bending part B. The position of the rotary encoder 14 of the second angle measuring device 10b effected thereby is then defined as its zero position. The output signals generated by the two rotary encoders 14 are passed via signal lines, not shown, to a control and evaluation device (also not shown) of the bending machine 1, which evaluates the signals of the two angle measuring devices 10a, 10b and controls the delivery of the bending roller 2c.

Will now the bending part B by the action of the bending direction acting in the bending tool 2 - like FIG. 2 seen - curved, this causes the measuring element 15 of the encoder 14 of the first and the second angle measuring 10a, 10b is deflected from its previously defined zero position, said deflection of the two measuring elements 15 of the two Winkelmeßeinrichtungen 10a, 10b - like out FIG. 2 can be seen - correlated to the bending caused by the bending of the bending part by the angle α1 and α2 from its initial position. This deflection of the measuring elements 15 is transmitted in each case via the axis A of the rotary encoder 14 to this and the Encoders 14 each generate a corresponding measurement signal, which is passed to the evaluation and control device of the bending machine 1. This compares now represented by the measurement signals of the encoder 14 actual value of the bending angle with the target value to be reached and generates a control signal which tracks the delivery of the bending roller 2a accordingly. From the measured springback of the bending part B, the correct overbending angle is then determined by which the bending part B is automatically deflected during the bending process in order to achieve the desired setpoint bending value.

In FIG. 5 a second embodiment of a device for detecting the bending angle of the bending part B is shown, which differs from the in the Figures 1 and 2 illustrated device 1 essentially differs in that the inlet side of the measuring arm 12 for the transmitter 11 is no longer designed as a joint-parallelogram 13, but that the angle measuring device 10a is arranged directly rotatable on the bending machine 1. It is preferred that the first angle measuring device 10a is not only rotatably mounted on the bending machine 1, but is linearly displaceable in a rail 20 functioning as a measuring arm.

However, the rotation of the first angle measuring device 10a is sufficient for a variety of applications, since - as already mentioned - the straight bending part B is not subjected to any action by the bending tool 2 in this area, so that only the deflection movement of the bending part B, which by the Actuation is caused by the bending tool 2, must be compensated.

Another difference between the two embodiments is the different configuration of the measuring element 15, wherein it is of course also possible that in the first embodiment of the device according to the FIGS. 1 to 5 the measuring element 15 according to the in the FIGS. 6 and 7 illustrated second embodiment is used. In the case shown here, this is about the axis A of the rotary encoder 14 rotatable measuring element 15 is formed as a measuring plate 18, are arranged on the Meßstifte 19, which are then brought to the bending part B in measuring system.

In the FIG. 8 Now, a third embodiment of the device is shown, wherein the same or corresponding components are provided with the same reference numerals and will not be described in detail. The essential difference between the measuring device of the first embodiment of FIGS. 1 to 5 and the third embodiment according to FIG. 8 is now that as a measuring arm 12 for the second angle measuring device 10a not a joint-parallelogram 13, but two linear guides 23a, 23b are used, wherein the second linear guide 23b is rotatably mounted in a slidable along the first linear guide 23a slide 24th The first angle measuring device 10a is in turn - as in the second embodiment - slidably mounted in a rail 20 and rotatably arranged on a plane orthogonal to the bending plane of the bending part B.

In FIG. 9 is now schematically a fourth embodiment shown, which its basic structure according to the third embodiment of the FIG. 8 like. The essential difference between the third and fourth exemplary embodiment is that the first angle measuring device 10a is no longer arranged in the rail 20 of the bending machine 1, but also on a linear guide 23b 'which is mounted on a slide 24' displaceably mounted along the linear guide 23. is rotatably arranged.

In the above description, it is assumed that always two Winkelmeßeinrichtungen 10 a, 10 b are required. In a number of applications, eg. B. in a four-roll bending, but undergoes the bending part B on the inlet side during the bending process no change in position, so it always remains in a defined position. The first angle measuring device 10a is therefore not required in this case.

In order now to bend the bending part B accurately, it is provided that the desired bending radius of the bending part B and the bending angle to be achieved is entered before the bending operation in the control and evaluation of the bending machine 1. From the bending radius and optionally from the diameter of the bending part B, a target settlement Q _{is then} formed, which calculates the settlement of the bending part B per degree of bending for the bending radius. This target processing Q _soll = distance / bending angle then represents the control variable for the bending radius to be generated by the bending machine 1 of the bending part B. The bending roller 2a of the bending tool 2 is then correspondingly delivered and the bending part B bent. The angle measuring devices 10a and 10b determine continuously, quasi-continuously or at discrete times the bending angle of the bending part B. The bending distance, ie the feed of the bending part B, is measured accordingly. From the ratio of the bending distance of the bending part B and the change of the bending angle, an actual settlement Q _is determined. Then, a target actual comparison of Q and _{Q should,} and the required adjustment (delivery) of the bending tool 2 is then calculated from this comparison, which is required so that Q _is of Q _will be equalized. If Q _is greater than Q _soll , the delivery of the bending roller 2a of the bending tool 2 is increased, so that the bending radius and thus Q _is smaller, until Q _is and Q _{is to} approach a predetermined tolerance. If Q _is less than O _soll , then the delivery of the bending tool 2 is reduced so that Q _is and the bend radius becomes larger, until Q _is again and Q _is to approach a predetermined tolerance.

This method has the advantage that it is possible in an advantageous manner, after shortest bending distances, so after only a slight advance of the bending part B in its feed direction to determine the bending radius of the bending part B, to control and regulate. This method therefore makes it possible to respond quickly to disturbances and changes during and before the bending process and to compensate for the effects caused thereby. The Disturbances and changes may be caused, for example, by changes in the bending-relevant material properties of the bending part B, by changing the dimensions of the bending part B (eg scattering of the diameter and scattering of the outer dimensions), by changing the bending tools 2, which builds up the benders by means of scale build-up, wear, or thermal influences, etc., arise, by changing the Maschineneinstellwerte the bending machine 1, z. As the machine position and the bending process speed, or by incorrect operator inputs.

In an advantageous manner, it may optionally be provided in the described method that the bending part B is bent over to compensate for the springback. In this case, the procedure is such that a certain number of degrees before reaching the desired bending angle or upon reaching the desired angle of the bending process is interrupted and the actual bending angle, the actual position of the bending rollers 2a-2c of the bending tool 2 and the feed of the bending part B measured becomes. Then a so-called intermediate deflection is performed, this intermediate deflection should correspond as exactly as possible to the programmed final deflection after reaching the desired bending angle taking into account the bending effect.

After this intermediate deflection, the bending angle is again measured, and the bending effect is calculated from the difference between the two measured bending angles. The bending machine 1 then reverses the bending direction, that is, the bending part B is moved in a direction opposite to the previous feed direction transport direction. In this case, the bending part B is bent again by the bending machine 1, so that the bending machine 1 is reset again to the starting position before Zwischenausbiegen. Then, a bending operation is performed in the original feed direction, the bending tools 2 being set in accordance with a bending angle corresponding to the target bending angle plus the bending effect determined as above.

By this procedure is achieved in an advantageous manner that matches the bending angle of the bending part B with the desired bending angle within predetermined tolerances after this bending process.

The method described is particularly suitable for bending bending parts B with unknown material behavior, since in these the springback can only be compensated empirically in this way.

Claims (15)

1. A bending machine having a device for detecting a bending angle of a part to be bent (B) that can be transported in a feed direction, the bending machine comprising bending rollers (2a-2c) through which the part to be bent (B) can be transported in a feed direction during the bending operation while the part to be bent (B) is subjected, in the bending machine (1), to the action of a bending tool (2) that acts in a direction different from the feed direction, characterized in that the device (1) comprises at least one angle-measuring device (10b) provided downstream of the bending tool (2) of the bending machine (1) in the feed direction of the part to be bent (B), that the at least one angle-measuring device (10b) comprises a transducer (11) equipped with a measuring element (15) that can be placed in measuring contact with the part to be bent (B), that at least the one angle-measuring device (10b) can be swung about an axis substantially orthogonal to the bending plane of the part to be bent (B), that the measurement signals produced by the angle-measuring device or devices (10a, 10b) placed in measuring contact with the part to be bent (B) can be directed to a control and evaluation unit of the bending machine (1), that the control and evaluation device determines the difference between the bending angles detected by the angle-measuring device (10b) at the beginning and at the end of the bending travel passed by the part to be bent (B), and determines from the ratio of the bending travel and the difference of the bending angles an actual bending value of the part to be bent (B), compares the latter with a nominal bending value and derives from that comparison a change in the setting of the bending tool that will compensate for the difference between the nominal bending value and the actual bending value.
2. The bending machine as defined in Claim 1, characterized in that the device (1) comprises a further angle-measuring device (10a) provided upstream of the bending tool (2) of the bending machine (1) in the feed direction of the part to be bent (B).
3. The bending machine as defined in Claim 1 or Claim 2, characterized in that at least one angle-measuring device (10a, 10b) comprises a transducer (11).
4. The bending machine as defined in any of the preceding claims, characterized in that at least one angle-measuring device (10a, 10b) comprises a rotary transducer (14) with an axis (A) on which is arranged a measuring element (15) that can be placed in measuring contact with the part to be bent (B).
5. The bending machine as defined in Claim 4, characterized in that the measuring element (15) of the angle-measuring device (10a, 10b) comprises a gripper unit (16) in which the part to be bent (B) can be fixed.
6. The bending machine as defined in Claim 5, characterized in that the gripper unit (16) of the measuring element (15) of the angle-measuring device (10a, 10b) comprises a U-shaped main body (16') within which the part to be bent (B) can be fixed in its position by a feed element (17).
7. The bending machine as defined in Claim 4, characterized in that the measuring element (15) comprises a plate (18) on which is arranged at least one measuring pin (19).
8. The bending machine as defined in any of the preceding claims, characterized in that at least one angle-measuring device (10a, 10b) comprises at least one measuring arm (12), preferably configured as a parallelogram linkage, the first end (12') of which preferably is movably connected with the bending machine (1), and the second end (12') of which carries the transducer (11).
9. The bending machine as defined in any of Claims 1 to 8, characterized in that at least one angle-measuring device (10a, 10b) comprises a measuring arm (12) equipped with two linear guides (23a, 23b; 23a, 23b') where one linear guide (23b, 23b') carries the transducer (11) on its end, and that one linear guide (23b, 23b') is rotatably seated on a slide (24, 24'), the slide (24, 24') being displaceably supported on the other linear guide (23a).
10. The bending machine as defined in any of Claims 1-9, characterized in that the measuring arm (12) is configured as a rail (20) in the working surface of the bending machine.
11. A method for controlling a bending machine (1) comprising a bending tool (2), wherein the part to be bent (B) is subjected to the action of a bending tool (5) that acts in a bending direction different from the feed direction of the part to be bent (B), characterized in that a nominal bending value in the feed direction of the part to be bent (B), required to obtain a predefined bending angle and a predefined bending radius of the part to be bent (B), is determined by a control and evaluation unit of the bending machine (1) and that the bending tool (2) of the bending machine (1) is adjusted with respect to its bending direction in accordance with that nominal bending value, that the part to be bent (B) is advanced in the feed direction through a bending travel and is bent by the bending tool (2) of the bending machine (1), that the bending travel of the part to be bent (B) is measured and the difference of the bending angles at the beginning and at the end of that bending travel is determined by a device (1) for detecting a bending angle, which device comprises at least one angle-measuring device (10b) arranged downstream of the bending tool (2) of the bending machine (1) in the feed direction of the part to be bent (B), and that at least one angle-measuring device (10b) comprises a transducer (11) having a measuring element (15) that can be placed in measuring contact with the part to be bent (B), that an actual bending value is derived from the ratio between the bending travel and the difference of the bending angles, that the control and evaluation device compares the nominal bending value with the actual bending value and, based on that comparison, effects a change in the setting of the bending tool (2) that compensates for the difference between the nominal bending value and the actual bending value.
12. The method as defined in Claim 10 or Claim 11, characterized in that a feed motion of the bending tool (2) is increased when the value of the actual deviation exceeds the value of the nominal deviation, or that the feed motion of the bending tool (2) is reduced when the value of the actual deviation is lower than the value of the nominal deviation.
13. The method as defined in any of Claims 10 to 12, characterized in that the bending process is interrupted a specified number of degrees before the desired bending angle of the part to be bent (B) is reached or when the nominal angle is reached, that the actual bending angle and the actual setting of the bending tool (2) as well as the feed position of the part to be bent (B) are measured, that thereafter an intermediate bending operation is carried out, after which the bending angle of the part to be bent (B) is measured again, and a bending effect is calculated from the difference between those two bending angles.
14. The method as defined in Claim 13, characterized in that after determination of the bending effect of the bending machine 1 its feed direction is reversed and the part to be bent (B) and the bending machine (1) are returned the initial positions occupied by them before the intermediate bending operation.
15. The method as defined in Claim 13 or Claim 14, characterized in that the bending operation is carried out by the bending machine (1) using a bending angle corrected by the bending effect.

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