EP1401595B1 - Method and device for determining the spatial geometry of a curved extruded profile - Google Patents

Abstract

Devices and methods for bending an extruded section of material held in a feed and fixing unit to yield a material with one or more bends and yielding a three-dimensional shape. In addition, devices and methods for further determining the three-dimensional geometry of the bent extruded section of material after one or more bending operations.

Description

Technical area

The invention relates to a method and a device for determining the geometry of a curved extruded profile, in particular a pipe, the in the region along a first rectilinear central axis (A) of the extruded profile in one Feeding and fixing unit held and by means of a bending device to a predetermined bending angle α is bent such that on one side of a caused by the bending curved portion of the extruded profile of the Area of the first rectilinear central axis (A) and at the opposite Page an area with a second rectilinear central axis (B) (see, for example, DE-A-19712685).

State of the art

Extruded profiles in the above sense are available by the meter, bar-like molded elements, the manufacturing and material-related along their extension have a minimum rigidity and that for spatial purposes Deformation can be subjected to a plastic bending process by the a permanent plastic bending deformation in the sense of a remaining curvature arises. In particular, this relates to pipes or extruded profiles made of solid material, which Metal exist and which it applies individually depending on their later Verwednung to deform.

The other versions relate mainly to pipes as hollow pipes consisting of plastically deformable material, preferably metal but can the following explanations also on extruded profiles of other geometries and Shapes are transferred, in which the spatial form changing measures too are meeting.

For example, pipes are in the form of piping systems for the transmission or Conduction of gaseous or liquid media and indicate depending on local Conditions along their extension curvatures or pipe bends. For example. be in this context on the used in the automotive sector, made of metal manufactured piping system, which filled with brake fluid for the Transmission of braking forces is used. To be such a piping system high demands on tightness and mechanical stability, so that the mostly running over several meters of pipes made in one piece are, despite the provision of a variety of bends and curves along the respective course of the pipeline, due to the very limited prevailing at the motor vehicle Course conditions.

Such, in the tube cross-section usually a few mm to cm measuring tubes are introduced for processing in corresponding bending devices in which the bending tube is fixed on one side and locally deformed by means of a bending head. Existing known bending devices are, for example, the DE 43 35 901 A1, DE 195 30 805 A1 and CH 689 378 A5 described. Bending machines can be basically divided into two categories, namely bending machines with stationary Bending head, in which the pipe to be bent usually consists of two bending jaws existing stationary bending head is fed via a feeding and fixing unit and plastically deformed by merging the two bending jaws becomes. Bending machines of the other category provide a moving bending head, in which relative to a fixed tube, a translational and rotational Moving bending head is moved, the appropriate place against the pipe is crimped locally to make a bend.

For checking and quality checking of the bending results, in itself known manner, the tube completely removed from the bending device and as loose single piece checked accordingly. Both come to the review touching, ie tactile working systems as well as non-contact, primarily based on optical basis measuring systems are used. tactile Measuring systems are so-called coordinate measuring machines or articulated measuring arms, by means of derer curved tube surface on a variety of surface areas scanned punctiform, with a number of three-dimensional Coordinate points are obtained relative to a reference coordinate system, from the following mathematical aprpoximation a complete Geometry of the bent pipe can be calculated.

Alternatively, contactless methods provide for the curved tube using point or line triangulation or Photogrammetry method to scan, also with mathematical Evaluation methods to determine the tube geometry.

Also, methods for determining the three-dimensional tube geometry are known by means of fork-shaped arrangements using optical light barriers working, which are moved along the extension of the curved tube and Here, 3-D surface points are detected, as already mentioned above a mathematical evaluation algorithm for determining the three-dimensional Room geometry are supplied.

Thus, in DE 43 30 420 A1 a pipe bending machine with one of a Slider-supported bending head described, which is a first to a housing of the Bending head stationary bending roller and a second arranged on a bending arm Bending roll has. The axes of the bending rollers are parallel to each other and perpendicular to the axis of the pipe to be bent. Furthermore, there are two drive motors one of which is for moving the carriage along a guide and thus for moving the bending head along the pipe and a second Drive motor for pivoting the bending arm about the axis of the first bending roller serves. In the gear train between the second drive motor and the bending head is an angle encoder provided, via which the bending angle (α) of the bending arm can be detected. The respective position of the bending arm with bending roller is by the angle encoder transmitted to a circuit, wherein by a desired-actual-value comparison the bending angle is determined.

By the circuit described in this document, it is thus only possible, the actual value of the movement of the bending arm with a in the Control to be entered setpoint value to compare. The springback of the tube, which results after loosening the tensioning device from the pipe, and can with this Device, however, not taken into account, since the bending angle only in the clamped Condition of the tube is determined.

A step further goes here DE 197 46 219 A1, in which a bending machine for Bending of rod-shaped material is described. The rod-shaped Material, in particular a pipe, is on a portion and at one of this Section subsequent to be bent pipe section held. Subsequently, will bent to be bent pipe section by a predetermined angle and the Springback of the bent pipe is measured, so that the pipe if necessary can be bent. After loosening the clamping device takes place on curved pipe section the measurement of springback. This happens by means of a Tastbolzens, which rests on the outside of the pipe wall, and through which the Auffedem taking place movement of the pipe leg relative to the in position held bending tool is transmitted to a Drehweggeber. That stands after opening the clamping device with unchanged position of the rest Machine elements the springback measure for the evaluation of the bending angle Available.

In US 5,992,210 is a device for bending an endless tube strand described. The device has a feed unit, one each Fixing unit for the pipe section to be bent and not to be bent and a swing arm through which the pipe section to be bent in the desired Shape is brought. After the bending process, the fixing device is located on the Swivel arm is located, solved and detected by sensors the shape produced.

All known methods for determining the three-dimensional geometry of space a bent extruded profile, in particular a bent tube adheres However, the disadvantage that the determination of the geometry of the room after successful Bending and complete detachment of the curved extruded profile from the Bending device takes place. Is it, for example, along a pipe a number incorporate different curvatures, wherein the bending operations for the Generation of the individual curves directly successively along the Tube can be performed, so can with the previously known techniques only the finished bent end product in its entirety is measured, after the fully bent tube is released from the bending device. Turns out that one of the number of incorporated curvatures is erroneous, for example, deviates the palatial bending angle of the desired target bending angle off, then the entire bent pipe is a waste product to watch. Is it, for example, to thin-walled pipe systems, such as, for example, as Brake pipes are used in the automotive sector, to the example above remain, so have reaching up to several meters, bent Pipes only have low intrinsic stability, leaving them without further Auxiliary templates for supporting the dead weight in their actual curved Room shape can not be measured.

Exact knowledge, however, about the exact spatial form of the bending process generated curvatures as well as knowledge of the entire actual spatial Shape of a curved Rorleitung, especially in the presence of a variety along a pipeline incorporated curvatures are particularly important for the Assessment of quality control, in particular for pipelines that are perfectly fitting must be inserted in corresponding counter-holders.

Presentation of the invention

The invention is based on the object, a method and an apparatus for Determination of the geometry of a curved extruded profile, which is in the area along a first rectilinear central axis (A) of the extruded profile in a feed and Held fixing and by means of a bending device to a predetermined Bending angle α is bent such that on one side of one by the bend caused region of the extruded profile of the region of the first rectilinear Central axis (A) and on the opposite side an area with a second rectilinear central axis (B), specify such that when provided a plurality along the tube to be performed successively bending operations every single bending angle should be determined exactly. Moreover, it applies through Measurement of further determining the geometry of the curved tube Parameter to measure, so that after a successful one-time bending operation immediately Statement can be made about whether the bending process the desired Achieved bending result.

The solution of the problem underlying the invention is in claim 1 specified. The subject of claim 18 is an inventive further developed device for bending extruded profiles. The Inventive ideas advantageous further-forming features are the subject of Subclaims and the description with reference to the drawings remove.

To determine by the bending process of an extruded profile, for example. A Pipe, generated bending angle, it is necessary that the bending process along a rectilinear portion of the tube is performed so that obtained after the bending process, a curved pipe area, on which connect rectilinear pipe sections on both sides. to Simplification of the presentation of the facts becomes as extruded profile a pipe but the tube can also be replaced by other alternatives, For example, by round rods made of solid material or other geometrically shaped Extruded profiles, such as flat materials, U- or V-shaped extruded profiles, to name a few call.

To determine the bending angle α, it is now the exact position of the two central axes the rectilinear pipe sections, each on both sides of the connecting curved pipe section to determine.

Due to the spatially defined arrangement between the tube feeding and fixing feeding and fixing unit and the bending device itself, in the the tube in the unbent state along its rectilinear Center axis (A) is guided, is the spatial position of the central axis (A) assuming a known coordinate system as known, By the way, this is not changed by the bending process. After done Bending process, it is therefore only the spatial position of the rectilinear Center axis of that rectilinear region of the tube to be found in Following feed direction to the bending device, so just that Area of the rectilinear pipe, the bending device before the bending process surmounted.

To determine the spatial position of the relevant center axis (B) is preferably a non-contact or tactile measuring sensor is used, its spatial position relative to the bending device and / or the feed and Fuser is known. The essential aspect of the invention The process now consists in carrying out the determination of spatial Position of the central axis (B) after completion of the bending process takes place, ie after the pipe is released from the bending device, allowing material-related Springback effects during the measurement process can be detected, and while the Pipe remains fixed or held in the feeding and fixing unit.

The tube thus remains during the measurement in a by the supply and fuser defines fixed position. Only then is it possible that after Completing the measuring process the pipe starting from the "frozen" Measuring position controlled in a subsequent bending position relative to Bending device can be spent, so that a subsequent bending process under solid spatial reference to the previous bending process performed on the pipe can be.

However, it turns out that during a bending process, the actual bending angle Taking into account by the release of the bent tube of the Bending device adjusting material-related springback of the desired Bending angle deviates too much, so either the bending process with the same or changed bending parameters or the pipe through a new pipe be replaced.

For the quantitative as well as qualitative assessment of the bending result, the determined bending angle α _is compared with a predetermined desired bending angle α _soll . If it turns out that deviations occur that go beyond a tolerance range also given, a signal is generated, which is used for a number of other measures.

If such a signal is obtained, then initially a qualitative statement about the bending quality are taken, such as rejects, no rejects, nor acceptable etc. For a required post-processing of a bend corrected bending parameters determined with which the bending process is repeated to to improve the bending result. Also, the corrected bending parameters further bending operations along the extruded profile are taken as the basis It may well happen that the material properties along the Extruded profiles change in this way due to the updated bending parameters can be taken into account

In an advantageous embodiment of the method according to the invention is proposed, in addition to the detection of the bending angle, as described above, also the feed lengths along the tube between two consecutive Bending operations to capture accurate knowledge of each other Distance between two curved pipe sections to obtain. In addition, will continue suggested the angle of rotation with a suitable angle of rotation measuring device measure the pipe along its central axis (A) during two Bending positions is rotated. On the basis of all the above information the bending angle, the feed length and the angle of rotation regarding a Variety of bending operations on a pipeline can be the entire spatial form of the curved pipeline can be detected and determined.

However, measuring the angle of rotation is not essential to the measure a possible twist between two consecutive bending operations to investigate. Since, as described above, the spatial position of the central axis B can be determined from this information not only in the by both Center axes A and B described lying bending angle α are determined, but also that angle to which the tube relative to the normal plane to Center axis A is bent.

Is the bending process completed along an extruded profile, so that on the Basis of a predetermined bending plan a desired, quite several Bends containing extruded profile is obtained, so in sync of all measured and stored measurement data the actual spatial form of the bent extruded profile compared with a desired room shape according to bending plan become. This comparison is primarily for product quality verification and Quality control.

A carrying out the above bending operation according to the invention Bending device for bending a strand profile with a feed and Fxiereinheit, by which the extruded profile can be fed and fixed as a straight piece by the meter and with one of the feeding and fixing unit in the feed direction along a rectilinear Central axis (A) of the extruded profile downstream bending device, with a at least two bending bodies existing bending head, which during the Bending the force applied to the extruded profile locally at least partially enclose and in an extruded profile releasing, open position are transferable, characterized by the fact that a measuring sensor with a fixed Spatial reference to the feeding and fixing unit and / or provided to the bending device is the spatial position of a rectilinear central axis (B) of the extruded profile in Area directly on the bending device in the feed direction of the extruded profile subsequently recorded. Furthermore, a memory and evaluation unit is provided, in the measured values of the measuring sensor can be stored and evaluated such that a Angle α, the so-called bending angle, can be determined by the center axes (A) and (B) is included. In this way it can be guaranteed that even after completion of the bending process information about the actual Room shape of the curved extruded profile are obtained, the one another Evaluation can be supplied.

Brief description of the invention

Fig. 1

schematisierte Darstellung einer erfindungsgemäß ausgebildeten Vorrichtung zur Erfassung der Raumgeometrie eines gebogenen Rohres.

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawing. It shows:

Fig. 1

Schematic representation of an inventively designed device for detecting the geometry of a curved tube.

Ways to carry out the invention, industrial usability

FIG. 1 schematically shows a device for bending or bending a tube 1 and for detecting the geometry of the space through the Bending process curved pipe course. The metered pipe 1 passes through a feed unit 2, consisting of two Wälzrollen, in as Counter-holder formed fixing unit 3, through which the tube 1 along its straight center axis A is pushed. Further, a bending device 4, consisting of an inner bending jaw 41 and outer bending jaw 42 provided, which can be transferred to the introduction of the tube 1 in an open position are. In Figure 1, the bending jaws 41 and 42 are in the closed position shown. The bending process of the tube 1 by means of the bending device 4 takes place such that the outer jaw 42 is the tube in a region to be bent 11 by rotation (see arrow) against the inner bending jaw 41 deformed. In this case, a straight pipe section 5, before the bending process oriented along the central axis A, inclined from the original central axis A. and has a rectilinear central axis B after the bend. The one of the Central axes A and B included angle α corresponds to the bending angle that it is to be determined exactly after completion of the bending process.

The measurement of the bending angle α is carried out by determining the spatial position of Central axis B, which adjoins the currently curved pipe section 5. The Determination of the central axis B, which at the same time also the Cytinderachse of the tube in the Area corresponds to 5, carried out with the aid of a non-contact sensor 6, the firmly attached to the outer bending jaw 42 and thus a solid Spatial reference to the bending device 4 has. Of course it is also possible to attach the sensor 6 regardless of the bending jaw 42, but at a appropriate positioning to be taken to ensure that a fixed spatial reference between the sensor 6 and the bending device 4 or the fixing unit 3 remains.

The sensor 6 is a laser sensor based on the triangulation technique, which has a Camera unit 61 and two formed as line laser light sources 62 has. With the help of an optical system, not shown, this light section sensor 6 projects on the Surface of the pipe each have one line per light source 62, through the Camera unit 61 is detected. With the help of the light section sensor 6 are along the light lines 3-D points on the pipe surface determined from which Cylinder approximation, the cylinder center axis, the so-called. Center axis B, is determined. The spatial position of the central axis A can be assumed to be known, especially this defined by the feeding and fixing unit 2, 3 and the bending device 4 is. From the spatial positions of the central axes A and B determined in this way can now be the bending angle α between the two axes A and B with respect to the spatial Cartesian coordinate system X-Y-Z can be determined. It is also also possible to determine from the information the angle under which the Center axis B, which intersects the Y or Z axis. This is also the twist angle of the pipe around the central axis.

In a further preferred embodiment, the sensor 6 or serves a additional measuring unit for detecting the external spatial form of the extruded profile, For example, to determine flattening of a pipe as an extruded profile. such Flattening can be achieved by means of the bending process, which it jeodch is to be specifically avoided, for example, by correcting Biegeparametem in another Bending or corrections with corre sponding.

Furthermore, it is possible using also determined sizes for feed V and Angle of rotation D of the supplied unbent pipe 1 and the metrological detected angle α, gradually the three-dimensional geometry of one of a Variety of individual rectilinear pipe segments and bends to determine composite pipe. This is done by adding all the data over the individual pipe sections, so that at the end of the bending process the complete three-dimensional spatial form of the curved tube available stands.

The course of the neutral fiber 7 within the tube 1, in particular in the area the bends 5, in which the neutral fiber 7 from the tube center in Direction of the inner radius shifts, is used in determining the length of the straight sections 5 are taken into account in the form of parameters. The parameters will be depending on the bending angle, pipe diameter, pipe material and Pipe wall thickness determined.

The apparatus shown in Figure 1 for determining the geometric shape of Tubes during the bending process in the machine allows for immediate Quality assessment of the shape and shape of a bent pipe. Especially Bending angle errors occurring during the bending process are detected immediately. Cause of this error is in particular a springback of the bent pipe after the bending process which among other things by fluctuations of Material properties is caused.

LIST OF REFERENCE NUMBERS

1

pipe

2

feeding

3

fuser

4

bender

41

inner bending jaw

42

outer bending jaw

5

straight pipe section

6

Triangulationslasersensor

61

camera

62

line laser

7

neutral fiber

Claims (27)

1. Method for determining the spatial geometry of a bent extrusion profile which is held in the region along a first straight-line central axis (A) of the extrusion profile in a feeding and fixing unit and is bent by means of a bending device through a predeterminable bending angle α such that on one side of a bent region of the extrusion profile brought about by the bending, the region of the first straight-line central axis (A) and on the opposing side a region with a second straight-line central axis (B) adjoin, characterised in that the spatial position of the second straight-line central axis (B) relative to the known spatial position of the first straight-line central axis (A) of the extrusion profile is determined, whilst the extrusion profile is held in a spatially fixed manner by the feeding and fixing unit and the bent region of the extrusion profile is released by the bending device, and that the bending angle α is determined by forming the intersection of the two axes (A) and (B).
2. Method according to claim 1, characterised in that the extrusion profile is fed longitudinally to the feeding and fixing unit in an unbent, straight-line form as continuous-length goods.
3. Method according to claim 1 or 2, characterised in that determination of the spatial position of the second straight-line central axis (B) is carried out with the aid of a contactless measuring method.
4. Method according to claim 3, characterised in that, as the contactless measuring method, a 3-D light-section method based on triangulation is applied, whereby a plurality of spatial points on the surface of the extrusion profile are detected in the region of the straight-line central axis (B) and, by means of mathematical approximation, the spatial position of the central axis (B) is determined.
5. Method according to claim 4, characterised in that the mathematical approximation is based on minimising the sum of least squares of the errors.
6. Method according to one of the claims 1 to 5, characterised in that the bending angle α is determined by means of triangulation.
7. Method according to one of the claims 1 to 6, characterised in that the bending angle α determined is compared with an expected bending angle α_target and, in the event of a deviation around a tolerance region, a signal is generated.
8. Method according to claim 7, characterised in that the signal for correcting bending parameters which control the bending process by the bending device is used.
9. Method according to claim 8, characterised in that the corrected bending parameters for a subsequent bending procedure on the previously bent region of the extrusion profile are used for after-correction.
10. Method according to claim 7 or 8, characterised in that the corrected bending parameters are made available for further bending procedures along the extrusion profile.
11. Method according to one of the claims 1 to 10, characterised in that after carrying out the determination of the bending angle α, the extrusion profile is displaced along the feeding and fixing unit and/or rotated, that a further bending procedure at a further point in the region along the first straight-line central axis (A) of the extrusion profile is carried out in comparable manner to the first bending procedure, and that a bending angle α' obtained through the further bending procedure is determined in the same manner according to claim 1.
12. Method according to claim 11, characterised in that a plurality of bending procedures with respective determination of the associated bending angles is carried out one after the other.
13. Method according to claim 11 or 12, characterised in that advancing of the extrusion profile along the feeding and fixing unit is detected between two sequential bending procedures.
14. Method according to one of the claims 11 to 13, characterised in that the rotation angle through which the extrusion profile is rotated between two sequential bending procedures is recorded.
15. Method according to claim 14, characterised in that after carrying out of a plurality of bending procedures, the overall spatial geometry of the bent extrusion profile is determined, based upon all the recorded data, namely the bending angles, advance lengths and/or rotation angles.
16. Method according to one of the claims 1 to 15, characterised in that the cross-sectional form of the extrusion profile is recorded.
17. Method according to claim 15, characterised in that the spatial geometry of the bent extrusion profile determined using measuring technology is compared with a given target spatial geometry, and that based on the comparison, a quality assessment is carried out.
18. Device for bending an extrusion profile having a feeding and fixing unit by which the extrusion profile is feedable and fixable as straight continuous-length goods and having a bending device arranged downstream of the feeding and fixing unit in the feeding direction along a straight-line central axis (A) of the extrusion profile, having a bending head comprising at least two bending bodies which, during the bending process, locally at least partially surround the extrusion profile to be bent applying a force and may be transferred into an open position releasing the extrusion profile, characterised in that a measuring sensor with a fixed spatial relation to the feeding and fixing unit and/or to the bending device is provided, which records the spatial position of a straight-line central axis (B) of the extrusion profile in the region directly following the bending device in the feeding direction of the extrusion profile, and that a storage and evaluation unit is provided in which measurement values of the measuring sensor are storable and evaluable such that an angle α, known as the bending angle, which is enclosed by the central axes (A) and (B) is determinable.
19. Device according to claim 18, characterised in that the measuring sensor is linked to the feeding and fixing unit or the bending device.
20. Device according to claim 18 or 19, characterised in that the measuring sensor is an optical measuring sensor.
21. Device according to claim 20, characterised in that the optical measuring sensor has at least two light sources and at least one light-sensitive sensor.
22. Device according to claim 21, characterised in that the light-sensitive sensor is a 3-dimensionally resolving sensor.
23. Device according to one of the claims 20 to 22, characterised in that the optical measuring sensor is a laser triangulation sensor.
24. Device according to one of the claims 18 to 23, characterised in that a travel measuring unit is provided in the region of the straight-line central axis (A), which records a length advance of the extrusion profile relative to the feeding and fixing unit.
25. Device according to one of the claims 18 to 24, characterised in that a rotation angle measuring unit is provided in the region of the straight-line central axis (A), which records a rotation angle through which the extrusion profile is rotated relative to the straight-line central axis (A).
26. Device according to one of the claims 18 to 25, characterised in that in the storage and evaluation unit, measurement values from the travel measuring unit and from the rotation angle measuring unit are storable and evaluable such that given a knowledge of the bending angle α, the complete spatial geometry of the extrusion profile may be determined.
27. Device according to one of the claims 18 to 26, characterised in that the extrusion profile is designed as a tube or as flat material.

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