WO1993001011A1

WO1993001011A1 - Method for finish bending of three-dimensionally bent workpieces, and finish bending station

Info

Publication number: WO1993001011A1
Application number: PCT/EP1992/001555
Authority: WO
Inventors: Walter Späth
Original assignee: Spaeth Walter
Priority date: 1991-07-12
Filing date: 1992-07-09
Publication date: 1993-01-21
Also published as: DE4123035A1; JPH06504235A; EP0548322A1

Abstract

The method proposed for finish bending three-dimensionally bent workpieces, in particular metal sections, calls for an automatic finish bending station to be located at the output of a bending machine in which the workpieces are bent in up to three dimensions. The workpiece is clamped at at least two clamping points and finish bent by hydraulic units located between the clamping points.

Description

-1-

Process for straightening three-dimensionally curved workpieces and associated straightening station

The present invention relates to a method for straightening three-dimensionally * bent workpieces and a straightening station belonging to them according to the preamble of patent claim 1.

The previously known bending processes can basically be divided into two different categories:

In the first type of bending process, the aim is to bend a workpiece as precisely as possible, in particular an elongated metal profile. This is usually done using a bending mold. These bending methods have become known from a number of patent applications which go back to the same applicant.

With these bending processes, which use complex technology, a relatively high bending accuracy of, for example, + _ 1.0 - 2.0 mm deviation can be achieved. Drawback, however, that a high Gerä ^'has teaufwand and that therefore such a bending process is expensive.

The second category of bending processes relates to bending deformations that work without a bending shape, where the workpiece is bent three-dimensionally in space without a bending template. Here too, a number of patent applications are known which go back to the same applicant. The advantage of this second category of bending processes is that they work with relatively little equipment and are therefore inexpensive. However, only a bending accuracy of, for example, + _^ 2 - 4 mm can be achieved.

The present invention is therefore based on the object of operating the three-dimensional bending, in particular of metal profiles, with high accuracy, using only a small amount of equipment shall be .

To achieve the object, the invention proposes a method according to the subject matter of claim 1.

An essential feature of the method is that an automatic straightening station is now arranged at the exit of the bending machine, which is capable of realigning the three-dimensionally bent workpiece with high accuracy, so that one can work with a relatively inexpensive bending method, which in itself still increases does not lead to high bending accuracy.

Only the combination of such a bending process in connection with the proposed straightening station then leads to a high accuracy of e.g. <= 1 *. , 0 mm.

It is now possible for the first time to guarantee three-dimensional forming of metal profiles in series production with high precision at relatively low cost. Metal profiles of this type are increasingly used, for example, in modern motor vehicle construction and replace the conventional passenger cells which are welded together from individual sheet metal parts. The passenger compartment of the motor vehicle is defined in the novel “space” frame profiles and therefore an extremely high level of accuracy is required for the three-dimensional bending of such metal profiles. It is therefore possible, for example, to work with a roll mandrel stretch-bending process that goes back to the same applicant, which is used without a bending mold and which is suitable for continuously processing metal profiles in a continuous process.

The final accuracy of the bent metal profiles which is still lacking in this method is then produced by the measuring-straightening station arranged at the exit of the bending station. To operate such a measuring-straightening station, it is provided that the three-dimensionally bent workpiece is clamped at at least two clamping points and directed between the hydraulic units arranged between the clamping points.

Such hydraulic units work according to the 3-point bending process, i.e. On the one side at the current bending point of the workpiece, two pistons of the piston-cylinder units rest at a distance from one another, while on the opposite side, in the space between the aforementioned pistons, a third piston presses on the workpiece and deforms the workpiece in the direction of the compressive force of this central piston .

According to the invention, the measuring-straightening station now consists of a large number of such 3-point bending units, such a 3-point situation, as previously described, not only being created with the help of directly opposite and adjacent hydraulic units, but also with the help of not hydraulic units lying directly next to each other.

In a first step, a mother profile with the desired contour is first scanned by a contour measuring system arranged in the straightening station.

This contour measuring system can either be designed without contact or in contact with the workpiece. For reasons of simplification, it is preferred if the contour measuring system is based on the probe principle and one probe is arranged on each hydraulic unit. This saves space and machine effort, because the displacement of the piston of the respective hydraulic unit can now be easily detected with the probe. The piston rods of the associated hydraulic units thus serve at the same time as probes, which are placed on the workpiece and detect the target contour of the nut profile.

Of course, the inventive concept of the present The invention also includes other measuring methods, such as optical measuring methods, which touch the target contour of the three-dimensionally bent workpiece without contact.

After the target contour has been captured by the mother profile, the profile to be straightened is moved into the straightening station and clamped in a second operation. In a third step, the actual contour of the workpiece is scanned with the same contour measuring system and the difference between the target contour and the actual contour is determined at any point on the workpiece. The number of measuring and alignment points depends on the required accuracy of the three-dimensionally bent workpiece. Then, depending on the correction value determined from the target and actual contour, the same hydraulic unit with which the actual and target contour was recorded at current points on the workpiece is adjusted.

Hydraulic units that can be freely assigned to each other form the previously described three-point straightening process, where in the space between two piston rods that are placed on the workpiece from one side, a third piston rod is pressed opposite the workpiece in the space between these two piston rods.

It should also be noted that practically every hydraulic unit defines a leveling plane.

The measuring alignment system consists of a box frame; in this longitudinal rails are attached to accommodate ring rails. The distance between these ring rails is infinitely variable in length and can be adjusted to each other with different axial dimensions (moved in parallel).

Slides can be freely rotated through 360 ° on these rings on rails. Usually there are two sledges on one common rail are arranged; if necessary, any more can be arranged. The longitudinal and circular adjustment is done manually (can also be done by motor).

On the slide, in turn, there are cylinders that can be moved linearly towards the center with a measuring probe on the head and with corresponding AC control for the cylinder itself.

A tensioning and transport system located in the longitudinal center receives a bent (spatially curved) bent part. An imaginary neutral center axis + _ 0 serves to accommodate the bent part (at least 2 stops in + _ O axis). Now the spatial contour is measured with reference to this zero axis. It is assumed that the curved contour corresponds exactly to the target dimension. You can measure with the linear units.

Structure of a linear unit:

An AC hydraulic cylinder records the measured value, which takes the contour at the measuring points to the + _ zero axis. This results in a certain number of coordinate points in space. A spatial contour can thus be precisely determined.

A bent part is now moved into the straightening station via the import station (AMRIS = automatic measuring and straightening system). The sensors on the linear units measure the difference between the actual and target status. The computer now sets the linear cylinder in motion and uses a linear pressure to correct the curve at certain points on the contour of the curved profile. Here the principle of 3-point bending is used in several sequences.

P, I,, 2, 2 ', 3, 3', 4.4 '

II and 1.2 like 4.1 and 4.2 have their own ring, ie I and II as well as 1.2 belong to a system, so also 4 'and 4.1 and 4.2.

Each linear unit therefore has an axis that can be controlled via CNC.

Experience in the bending of several pre-samples allows the range of greatest tolerances to be narrowed relatively precisely. As a result, the measuring and straightening units on the contour can also be precisely determined with their position.

A handling system e.g. a three-dimensionally curved frame is placed on the extended clamping system and fastened (clamping jaws) in a predetermined spatial position. After inserting the frame, measurement and straightening begin immediately.

After straightening, the bent part is brought to the export station and transported on by another handling system. The clamping system moves back into the insertion station and picks up the next bent part in time with the bending process. The program can already be created using the known measuring points of a teaching = the reference points of the AMRIS system match the measuring points of the teaching system (see coordinate structure). See registration "Bending Gauges and Bending Tools for ASB and RASB from the same applicant.

The AMRIS consists of one or more straightening units. A straightening unit consists of 3 linear measuring straightening stamps per side.

Measuring pressure 2 belongs together counter pressure i '+ 3

or Measuring pressure 2 'belongs together counter pressure I + 3

Appropriate control means that the system can be varied continuously along the longitudinal axis, e.g.

Measuring pressure 3 belongs together Counter pressure 2 '+ 4'

or

Measuring pressure 3 'belongs together, etc.

Back pressure 2 + 4

Now the same arrangement can be rotated by 90 ° additionally.

Depending on the contour of the bent frame part, the linear-measuring-straightening units can also be swiveled in the longitudinal direction to ensure that the measuring-straightening plungers are placed at right angles on the shaped profile.

The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another. All information and features disclosed in the documents - including the summary -, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are new to the prior art, individually or in combination. The invention is explained in more detail below with the aid of drawings which illustrate only one embodiment. Further features and advantages of the invention which are essential to the invention emerge from the drawings and their description.

Show it:

Figure 1: schematically shows a perspective front view of the straightening station;

Figure 2: the straightening principle of the straightening station according to Figure 1 in one plane;

Figure 3: schematically a machine structure;

Figure 4: the directional principle in a plane perpendicular to Figure 2;

Figure 5: a modification of the directional principle compared to Figure 2;

Figure 6: schematically in side view the upper part of the mounting of a longitudinal rail for holding a hydraulic unit.

The workpiece 8 to be straightened is clamped in a box frame 7 at its two ends at the clamping points 9, 10.

The arrows drawn in four different directions at the clamping points 9, 10 symbolize that the workpiece 8 is clamped from all sides.

FIG. 3 also shows that the clamping point 9 is designed as a fixed point 11 (immovable), while the clamping point 10 is designed to be displaceable in the direction of the arrows 12. In this way, build-up of mechanical stresses during the straightening of the workpiece is avoided and such stresses result in changes in length u set and move the clamping point 10 in the arrow directions 12

On the workpiece 8, reference points 51, 52, 53, 54 ... etc. Are now set at infinitesimally small intervals. Defined, the number and the distance of the alignment points depend on the required accuracy and on the type and design of the workpiece.

Each directional point 51 54 lies in the plane of a circular disk 41-45, with each circular disk also being defined as a straightening plane 31-36.

The term "circular disk" 41-45 means that the outer circumference of each circular disk 41-45 is defined by an annular rail 57 (FIG. 6) and that hydraulic units 1-6; 1 '-6 * are arranged.

In relation to the straightening plane 32 and the associated circular disk 41, this means that the outer circumference of the circular disk 41 is defined by an annular rail 57 and that two hydraulic units 1, 1 'located opposite one another are arranged in the region of the annular rail via the holder shown in FIG.

The same applies to the straightening plane 32 and the associated circular disk 42, in the area of which hydraulic units 2, 2 ′ are located opposite one another.

Analogously, this also applies to the other straightening planes 33-36 and the associated circular disks 43-44.

For reasons of simplification in the drawing, not all circular disks belonging to the corresponding straightening planes 31-36 of FIG. 2 were shown in FIG. 1.

It can also be seen from FIG. 1 that the clamping point 9 is also arranged in the region of a circular disk 10, just like that Clamping point 10 is arranged in the area of a circular disk 45. Both circular disks 40, 45 are in turn defined on their outer circumference by an annular rail 57, in the area of which a large number of hydraulic units are slidably arranged, as is symbolized by the four arrows in the area of the circular disk 40 and in the area of the circular disk 45.

As already described at the beginning, each hydraulic unit 1-6 and 1'-6 'is coupled to a length measuring system, so that, according to FIG. 1, the target contour of a workpiece 8 can be detected in the area of the guide points 51-54 by the hydraulic units 1-6 and l'-6 'are brought up to the workpiece until they are seated on the outer circumference of the workpiece with a defined force that does not lead to a deformation of the workpiece 8. The then associated displacement of the individual piston rods of the hydraulic units is then communicated to the respective length measuring system and a target contour of the workpiece to be measured is formed from this in a connected computer.

After the detection of the target contour, the nut profile is removed from the straightening station 27 and a workpiece 8 to be adjusted is clamped in the same way as shown in FIG. 1. The directional principle will now be explained with reference to FIG 2.

As already mentioned at the beginning, each circular disk 41-44 defines a straightening plane 31-36, a 3-point straightening method being used. This means that the hydraulic units 1 and 3 with the hydraulic unit 2 'acting in the opposite direction form a 3-point straightening system, just like the 3-point straightening system from the hydraulic units 1' and 3 'which are arranged with the upper and in the space Hydraulic unit 2 also form a 3-point straightening system.

It is now important that the 3-point straightening system does not necessarily have to be formed by hydraulic units lying next to one another, but that any variation among the different ones Hydraulic units 1-6 and T-6 'can be formed.

For example, it is possible to design a 3-point straightening system from the hydraulic units 1 and 4 in connection with the hydraulic unit 3 'acting in the opposite direction, with a second hydraulic unit 2' also being able to be added to this hydraulic unit 3 'acting in the opposite direction . Likewise, for example, the hydraulic units 1 and 6 in connection with the hydraulic unit 4 'or with any other hydraulic unit acting in the opposite direction, for example the hydraulic units 3 ¹ and 4' and 5 ', could form such a 3-point straightening system.

This results in the universal replaceability of the measuring-straightening station according to the invention, which ensures that any interchangeable and selectable 3-point straightening systems can be formed according to the control of the hydraulic units arranged next to one another at infinitesimally small distances.

It is important here that the hydraulic units 1-6 and l'-6 'can act as desired in the straightening planes 31-36, so one must imagine circular disks perpendicular to the paper plane in the paper plane of FIG. 2, in the area of which the hydraulic units 1 -6 and l'-6 'are arbitrarily movable in the area of their ring rails 57. Thus, the hydraulic units in the area of the alignment points 51-54 can be rotated through an angle of rotation of 360 ° and thus act at any point on the circumference of the workpiece 8 to be straightened and exert pressure there.

FIG. 3 shows a schematic diagram of a mechanical implementation of a system according to the invention for carrying out the method.

In a bending machine 13 controlled by a CNC control 16, a cutting knife 14 is arranged at the output, which is in the direction of the arrow 15 is movable and cuts the workpiece bent by the bending machine 13. The workpiece is gripped at one end by a clamping carriage 20 ′, which is arranged with its slide on a conveyor belt 18, which can be moved in the direction of arrow 19 and in the opposite direction. The clamping carriage 20 'is moved in the direction of arrow 19 into its position 20, so that the workpiece 8 is moved into the region of the directional station 27.

The previously described import station 17 opposite the

Straightening station 27 is assigned to an export station 21, which also has a clamping carriage 22 which can be moved in the direction of arrow 24 with a conveyor belt 23.

Otherwise, the conveyor belts 18 and 23 are driven by corresponding motors 25.

While one clamping carriage 20 is locked in the fixed point 11, the other clamping carriage 22 is held in the arrow 22 in the export station 21 so as to compensate for corresponding mechanical stresses which are exerted on the workpiece 8 during straightening. The straightening station 27 and the import and export stations 17, 21 are controlled by a CNC controller 26.

The hydraulic units 1-6 and l'-6 'of the straightening station 27 are supplied with pressure oil by a hydraulic unit 29, which hydraulic unit 29 is driven by a motor 28. As explained with reference to FIG. 1, the workpiece is clamped in such a way that the clamping points 9, 10 are as far as possible in the neutral central axis 30 (see FIG. 1).

After the target contour of a mother profile has already been recorded, the actual contour of the workpiece 8 to be straightened is now recorded in the situation according to FIG. 3, and the hydraulic units 1-6 and r-6 'are controlled accordingly by the CNC controller 26 in order to to implement the 3-point directional principle explained with reference to FIG. 2. It is important here that each hydraulic unit according to FIG. 4 can be displaced in this plane in the area of its circular disk 41 by a pivoting range 37 of, for example, 90 °, so that the hydraulic unit 1 can be pivoted into the positions 1 "or 1 '*'. The same applies otherwise for the hydraulic unit 1 ', which is also displaceable in the other swivel ranges.

FIG. 5 also shows that the hydraulic units 1-6 and l'-6 'can be inclined by an angular range 38 in order to ensure that they always touch the surface of the workpiece 8 in their assigned direction. That is, the inclination of the hydraulic units 1-6 and l'-6 'is adjustable and lockable.

FIG. 6 shows a mechanical implementation, for example a first slide 49, which carries an annular rail 57, is arranged on an upper side member 47 of the box frame 7 (see FIG. 1). According to the present description, the ring rail 57 defines the outer circumference of a circular disk 40-45. ^"

A second slide 55 with support rollers 56 engages in the area of this ring rail, which represents a closed ring part, this slide 55 carrying the hydraulic unit 1. The piston rod 58 rests with its punch 59 on the surface of the workpiece to be straightened. The stamp 59 can be adapted to the surface of the workpiece in order to ensure a positive fit.

The piston rod 58 is arranged displaceably in the direction of arrow 60 in the hydraulic unit, the length measuring device 61 described being arranged on the piston rod -58. It goes without saying that the length measuring device 61 is also arranged on the other cylinder side of the hydraulic unit, ie on the back of the cylinder.

The hydraulic unit 1 is held in the carriage 55 with a locking screw 50 in order to ensure a first adjustment movement by hand on the workpiece. This can be used to ensure a specific zeroing of the respective hydraulic device.

Because the carriage 49 is arranged on the longitudinal beam 47 so that it can move in the direction of the arrows 48, the mutual distance between the circular disks 40-45 can thus be set continuously and the distance between the reference points 51-54 can thus be set continuously. With the measuring-straightening station described, it is now possible for the first time to achieve a high precision of three-dimensionally bent workpieces, because an inexpensive bending machine 13, which does not bend with high precision, is combined with a straightening station 27 according to the present invention, and thereby as a whole in series production Workpieces 8 can be produced with high bending accuracy.

DRAWING LEGEND

Piston rod stamp arrow directions length measuring device

Claims

Patent claims

1. A method for straightening three-dimensionally bent workpieces, in particular metal profiles, characterized in that the three-dimensionally bent workpiece (8) at the output of a bending machine (13) in an automatic measuring-straightening station (27) at at least two clamping points (9, 10) arranged hydraulic units (1-6, l'-6 ') is directed.

2. The method according to claim 2, dadurchgekennzechnet that in a first operation, a mother profile having the target contour is first scanned by a length measuring system, with each hydraulic unit (1-6, 1'-6 ') being assigned a length measuring device (61) that in in a second operation, a workpiece (8) to be straightened is moved into the straightening station (27) and clamped in such a way that the actual contour of the workpiece (8) is scanned in a third operation and the difference between the target contour and the actual contour is determined and that depending on that the hydraulic units (1-6, 1'-6 ') forming the respective straightening planes (32, 36) are determined from the correction value determined from the target and actual contour.

3. The method of claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the workpiece (8) at a mutually pointing points (51-54) is directed in all three spatial levels.

4. The method according to any one of claims 1-3, characterized in that each straightening point (51-54) is assigned a straightening plane (32-36), that the straightening plane is arranged perpendicular to the neutral central axis (30) of the workpiece (8) and that at least one hydraulic unit t (1-6, l'-6 ') is arranged in the straightening plane (32-36) and exerts compressive force on the workpiece (8).

5. The method according to claim 3, characterized in that the hydraulic units (1-6, 1'-6 ') of different straightening levels (32-36) cooperate in such a way that between each of a side pressure on the workpiece (8) exerting hydraulic units ( 1,3) a hydraulic unit (2 ') exerting pressure on the workpiece (8) is arranged on the opposite side.

6. straightening station for carrying out the method according to any one of claims 1-5, characterized in that the workpiece (8) clamped in the vicinity of its two ends (clamping points 9,10), that several in the area between the clamping points (9,10) , a mutually spaced alignment levels (32,36) are arranged and that in each leveling plane (32,36) at least one hydraulic unit (1-6, l'-6 ') exerts pressure on the workpiece (8).

7. straightening station according to claim 6, characterized in that in each straightening plane (32-36) two, substantially opposite hydraulic units (1,1 '; 2,2 "; 3,3'; 4,4 '; 5,5' ; 6,6 ') are arranged.

8. straightening station according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the direction of attack of each hydraulic cylinder (1,1 '... 6,6') in the straightening plane on the workpiece (8) is adjustable (Fig. 5).

9. straightening station according to one of claims 6-8, characterized in that in a box frame (7) a number of several, spaced apart ring rails (57) are arranged that on each ring rail (57) at least one carriage (55) slidably and it can be determined that a hydraulic unit (1-6; 1'-6 ') is attached to each slide (55), the piston rod (58) of which acts on the workpiece (8) and that the displacement of the piston rod (58) is detected by a length measuring device (61).

10. straightening station according to one of claims 6-9, d a d u r c h g e k e n n z e i c h n e t that the ring rails (57) in the direction of the central axis (30) of the straightening station (27) are arranged displaceably and lockable.