US20090301160A1

US20090301160A1 - Flanging machine and method for spin-flanging workpieces

Info

Publication number: US20090301160A1
Application number: US12/281,945
Authority: US
Inventors: Jens Baumgarten; Peter Plapper
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2006-03-07
Filing date: 2007-03-07
Publication date: 2009-12-10
Also published as: RU2008139628A; WO2007101667A1; CN101394951A; CN101394951B; DE102006010469A1; RU2425725C2

Abstract

A crimping device (1) comprising a crimping bed (12) provided for receiving a workpiece (10), a multiaxial manipulator, in particular an industrial robot (2), which has a crimping tool (5) with at least one crimping roller (6) on its hand, is intended to avoid fold formation on the flange (11), particularly during the pre-crimping. To this end, at least parts of the crimping roller (6) have the form of a cone or a truncated cone having an axis of symmetry (27), an apex (26), and an opening angle α, wherein for the opening angle α of the cone it holds that 180°>α≧140°.

Description

The invention relates to a crimping device comprising a multiaxial industrial robot, in particular an industrial robot which has a crimping tool with a crimping head on its hand and at least one crimping roller located on the crimping head.
Such a crimping device is known, for example, from DE-U-299 10 871. The robot-guided crimping tool disclosed therefore has a crimping roller by which means a crimping flange is folded over and pressed down on a workpiece. The pre- and finish-crimping can optionally take place in a plurality of operations.
When using such a crimping device, however, the formation of folds in the material of the flange frequently occurs during the pre-crimping. These folds must be eliminated to prepare a defect-free surface in the finish-crimping step, which however is typically only possible in a restricted scope and additionally requires expenditure.
It is therefore the object of the invention to provide a crimping device, which allows fold-free crimping of workpieces in the simplest possible manner.
In addition, it is a further object of the present invention to provide a method for roll crimping of workpieces, by which means the formation of folds can be reliably avoided.
According to the invention, this object is achieved with the subject matter of the independent patent claims.
Advantageous further developments of the invention are the subject matter of the dependent claims.
An inventive crimping device comprises a crimping bed provided for receiving a workpiece and a multiaxial manipulator, in particular an industrial robot, which has a crimping tool with at least one crimping roller on its hand. At least parts of the crimping roller have the form of a cone or a truncated cone having an apex, an axis of symmetry running through said apex, and an opening angle α, wherein for the opening angle α of the cone it holds that 180°>α≧140°.
The invention starts from the consideration that fold formation during pre-crimping should be avoided a priori. As has been shown in experiments and in simulations, fold formation can be attributed to local elongations of the material, particularly in the vicinity of the flange edge, during pre-crimping.
Particularly in the area of the flange edge, the local elongation of the material should therefore be kept relatively low. The elongation which comes about due to the flange material “winding round” the crimping roller, can be reduced particularly in the area of the flange edge by selecting the crimping roller to be a conical one instead of the conventional cylindrical crimping roller, wherein “conical” is used here and subsequently as an abbreviation and means a crimping roller which either has the shape of a full cone or that of a truncated cone or which has the shape of a full cone or that of a truncated cone at least in some areas.
As a result of its straight guidance by the robot, such a conical crimping roller does not roll on the entire circumferential surface of the cone but strictly speaking, only on a circle line. The other areas of the circumferential surface exert a significantly lower pressing pressure on the flange. Thus, the pressing pressure has a gradient along a section on the circumferential surface between the base area and the apex of the cone, which is suitable for preventing local elongations of the flange edge.
As has been found, the strength of the gradient in the pressing pressure is optimal when the opening angle α of the cone is at least 1400, preferably at least 1600.
In addition to the opening angle of the cone, further parameters such as, for example, the diameter of the crimping roller are important for avoiding local elongations. The base area of the conical crimping roller advantageously has a diameter d of at least 60 mm.
In one exemplary embodiment of the invention, the conical crimping roller is provided as a pre-crimping roller and a cylindrical further crimping roller is provided as the finish crimping roller. However, the crimping roller can also be configured such that it has a conical or frustro-conical region and in addition, a cylindrical region so that it can be used as a pre-crimping roller and as a finish-crimping roller.
The crimping roller is advantageously disposed fixedly on a driven shaft of a drive, by which means the crimping roller can be driven at a defined rotational speed during the crimping. The direction of rotation of the crimping roller takes place in the direction of the traveling industrial robot, wherein the rotational speed of the crimping roller is higher than the traveling speed of the industrial robot.
The friction between the crimping flange to be crimped and the surface of the crimping rollers machining the crimping flange should be as high as possible. “Spinning” of the driven crimping rollers on the crimping flange should be avoided under all circumstances. In this case, it has been found to be an expedient embodiment for the crimping rollers to make the crimping rollers of a hard metal core, preferably a steel, with a hard rubber cladding located thereon. The hard rubber cladding can be vulcanized thereon.
The inventive apparatus has the advantage that the flange material is less severely locally elongated than by conventional crimping rollers due to the optimized conical geometry of the crimping roller. As a result, fold formations on the workpiece occur less frequently and also expensive efforts to reduce the folding during finish crimping or a reduction in the translational speed can be dispensed with.
According to the present invention, a method for the roll crimping of metal parts comprises the following steps: firstly, a workpiece to be crimped is provided with a flange located on a crimping bed. The flange is pre-crimped with a pre-crimping roller guided by a multiaxial manipulator, for example, an industrial robot, the pre-crimping roller has the shape of a cone or truncated cone, having an axis of symmetry, an apex and an opening angle α, and the opening angle α of the cone is at least 140°. The flange is then finish-crimped, preferably with a cylindrical finish crimping roller.
Due to the optimized conical geometry of the crimping rollers, less severe local elongations than in conventional methods, which could lead to fold formation, occur particularly in the proximity of the flange edge. In this case, there are two possibilities for the guidance of the crimping roller:
Either the axis of symmetry of the conical crimping roller is approximately perpendicular to the plane of the crimping bed during the crimping process. In this case, “approximately perpendicular” means that the axis of symmetry passes through the plane of the crimping bed at an angle of greater than 45°.
In this case, the axis of symmetry of the pre-crimping roller is advantageously turned through an angle g in the counterclockwise direction toward the perpendicular to the direction of translation.
However, the axis of symmetry of the conical crimping roller can also be approximately parallel to the plane of the crimping bed during the crimping process. In this case, “approximately parallel” means that the axis of symmetry passes through the plane of the crimping bed at an angle of less than 45°.
In this second case, the axis of symmetry of the pre-crimping roller is advantageously turned through an angle g in the clockwise direction toward the perpendicular to the direction of translation.
Before the beginning of the pre-crimping, the flange angle γ between the flange and the crimping bed and therefore the plane of the workpiece should therefore be at most 90°.
The translational speed v₁at which the crimping roller is guided during the pre-crimping is advantageously between 1000 mm/s and 1600 mm/s. A plurality of pre- or finish crimping steps can be provided both for the pre- and finish-crimping of the flange.
The crimping device is particularly suitable for the roll crimping of vehicle parts such as automobile doors, hoods, and tailgates.

Exemplary embodiments of the invention are explained in detail hereinafter with reference to the appended figures.

FIG. 1 shows in schematic side view a crimping device with an industrial robot and a crimping tool with a driven crimping roller;

FIG. 2 shows schematically a crimping roller according to a first embodiment;

FIG. 3 shows schematically a crimping roller according to a second embodiment;

FIG. 4 shows schematically a crimping roller according to a third embodiment;

FIG. 5 shows schematically a side view of the crimping roller during the crimping process;

FIGS. 6 and 7 show two possibilities for carrying out the roll crimping. In this case,

FIG. 6 a shows schematically a side view of a first possibility;

FIG. 6 b shows schematically the first possibility from another perspective;

FIG. 7 a shows schematically a side view of a second possibility;

FIG. 7 b shows schematically the second possibility from another perspective

The same parts are provided with the same reference numerals in all the figures.
FIG. 1 shows in a schematic diagram a crimping device 1, which principally consists of a six-axis industrial robot 2 and a crimping tool 5.
The crimping tool 5 is moved by the industrial robot 2 with respect to a workpiece 10 having one or more crimping flanges 11, which is disposed in a fixed position on a framework and clamped there on a crimping bed 12.
The framework can also be designed as a rotary table (not shown), on which the crimping bed 12 is mounted, wherein the rotary table is turned in the direction opposite to the direction of travel of the robot and for this purpose is incorporated in the controller of the industrial robot 2 or accesses a common controller.
The industrial robot shown in FIG. 1 has six axes of rotation. However, the number of axes can be smaller or larger. The industrial robot 2 has a robot controller 13, by which means its movements, and optionally also the process sequence of the crimping, can be controlled and regulated. To this end, a movement sequence of the robot 2 and the crimping tool 5 derived from the contour of the clamping flanges is programmed in the robot controller 13 and the CAD and/or CAM data of the workpiece 10 is stored in a random access memory.
The industrial robot 2 has a rocker arm and an outrigger 3, having a robot hand 4 with one or more movement axes disposed at its front end. On the driven side, the robot hand 4 has a hand flange to which the crimping tool 5 is flange-mounted.
The crimping tool 5 shown in FIG. 1 has a crimping roller 6. The crimping roller 6 is firmly fastened to a driven shaft 7. The driven shaft 7 is in communication with a transmission 8, which is flange-mounted to a drive motor 9. Transmission 8 and drive motor 9 are located inside the crimping tool 5.
In order to execute the roll crimping on the workpiece 10, the industrial robot 2 is set in motion by the controller 13 and travels around the crimping flange 11 at a speed v₁. At the same time the crimping roller 6 is pressed onto the crimping flange so that the crimping roller 6 folds the crimping flange downward. The crimping roller 6 is thereby set in rotational movement, which is effected via the drive motor 9, the transmission 8, and ultimately the driven shaft 7. The rotational movement of the crimping roller 6 is effected in the direction of travel of the robot 2 along the outer contour of the crimping flange 11.
The rotational speed v₂or the rotational speed of the crimping roller 6 is in this case greater than the speed of travel v₁of the moving robot 2. Accordingly, it holds that v₂>v₁. The speed v₁of the industrial robot 2 is typically between 1000 mm/s and 1600 mm/s.
As a result, the workpiece in the area of the crimping flange 11 is pulled by the crimping roller 6 slightly in the direction opposite to the direction of travel of the robot 2. Any bunching of the workpiece 10 in the area of the crimping flange 11 is thereby reduced.
The industrial robot 2 has a robot controller 13, which measures and adjusts the movements and the entire process sequence of the roll crimping executed. The robot controller 13 is designed as a computer-aided controller with one or more processors, a plurality of interfaces for input and output of data, and a plurality of memories for operating, process, and other relevant data.
The track course and the corresponding movement sequence of the industrial root 2 and of the crimping tool 8 are programmed in the robot controller 13 and stored in a random access memory.
In the area of its crimping head 15, the crimping device 1 has a measuring device 20 which measures the crimping values detected from the crimping process. The measuring device 20 is connected to the robot controller 13 via a line 19. The robot controller 13 is in turn connected to the industrial robot 2 by means of a line 21.
The measuring device 20 in particular measures the rotational speed and the pressing pressure of the crimping roller 6 during the roll crimping and readjusts this by means of a desired value/actual value comparison. The readjustment in particular takes account of the exact adjustment of the rotating crimping roller 6.
Since the speed of travel of the robot 2 during travel around and processing of the workpiece 11 can be different, the rotational speed of the driven crimping roller 6 must be matched to this. This matching is also carried out via the robot controller 13, in which the rotational speed of the crimping roller 6 is adjusted by means of the program data stored in the random access memory depending on the speed of travel of the robot 2.
In order to effectively prevent the bunching of the workpiece 10 in the area of the crimping flange 11, which leads to fold formation at the crimping flange 11, the crimping roller 6 has a special geometry.
FIGS. 2, 3, and 4 show schematically alternative embodiments of the crimping roller 5.
The crimping roller 6 according to FIG. 2 has the form of a cone having a circumferential surface 14 and a base area 16. The geometry of the cone is characterized by its opening angle α and the diameter d of its base area 16. An opening angle α of at least 140° is particularly favorable for avoiding fold formation. The diameter d is at least 60 mm.
The crimping roller 5 can either have the form of a full cone, as shown in FIG. 2. However, it can also have the form of a truncated cone, as shown in FIG. 3. The conical or frustro-conical roller 6 is used for pre-crimping the workpiece 10. A cylindrical finish-crimping roller, not shown, can be used, for example, for the finish-crimping.
However, the operations of pre- and finish crimping can also be executed with a single crimping roller 6. For this, the crimping roller according to FIG. 4 has a conical region 25 for pre-crimping and a cylindrical region 23 for finish-crimping. Both the pre- and the finish-crimping can be executed in several passes.
FIG. 5 shows schematically a side view of the conical crimping roller 6 and the crimping flange 11 during the crimping process.
The crimping roller 6 is set so that in a first region 18, it is pressed with relatively high pressing pressure onto the crimping flange 11 and nestles closely against this flange. In a second region 22, which lies closer to the apex, the radius of the crimping roller 6 is significantly smaller as a result of its conical geometry and the circumferential surface 14 of the cone does not nestle so closely against the crimping flange 11 in this second region 22. The crimping roller 6 does roll on its entire circumferential surface 14 but strictly speaking, only on a circle on the circumferential surface.
Local elongations, which can lead to fold formation in the crimping flange 11, come about due to the “winding around” of the flange material around the crimping roller 6. As a result of the smaller radius in the second region 22, which lies closer to the apex, the cone geometry results in a particular small local elongation in the proximity of the flange edge 24.
The flange 11 forms a flange angle γ with the plane of the workpiece 10. Before the beginning of the pre-crimping, this flange angle γ should be at most 90°.
FIGS. 6 and 7 show two different possibilities for guiding the crimping roller 6.
In FIG. 6 a the axis of symmetry 27 of the conical crimping roller 6 lies approximately parallel to the plane of the crimping bed 12 and therefore substantially also to the surface of the workpiece 10. The apex 26 is facing the workpiece 10. “Approximately parallel” means in this case that the axis of symmetry 27 passes through the plane of the crimping bed 12 at an angle of less than 45°.
In this alignment of the crimping roller 6, the angle β, as shown in FIG. 6 b, according to the mathematical definition should be negative, that is, it should have come about through a clockwise rotation from the perpendicular 28 to the direction of translation v₁.
In the alternative possibility according to FIG. 7 a, the axis of symmetry 27 is approximately perpendicular to the plane of the crimping bed. “Approximately perpendicular” means in this case that the axis of symmetry 27 passes through the plane of the crimping bed 12 at an angle of greater than 45°.
In this alternative alignment of the crimping roller 6, the angle β, as shown in FIG. 7 b, according to the mathematical definition should be positive, that is, it should have come about through a counterclockwise rotation from the perpendicular 28 to the direction of translation v₁.

REFERENCE LIST

1 Crimping device
2 Industrial root
3 Outrigger
4 Robot hand
5 Crimping device
6 Crimping roller
7 Driven shaft
8 Transmission
9 Drive motor
10 Workpiece
11 Crimping flange
12 Crimping bed
13 Robot controller
14 Circumferential surface
15 Crimping head
16 Base area
17 First region
18 Line
19 Measuring device
20 Line
21 Second region
22 Cylindrical region
23 Flange edge
24 Conical region
25 Apex
26 Axis of symmetry
28 Direction perpendicular to v₁
α Opening angle
β Angle of travel
γ Flange angle
v₁Translational speed

Claims

1. A flanging machine comprising:

a flanging bed adapted to receive a workpiece; and

a multi-axle manipulator adapted to carry a flanging tool at a hand with at least one flanging role,

wherein at least one part of the flanging role has a form of a cone with an apex, an at least substantially symmetrical axle running through the apex, and an apex angle α of a specified surface area to be pressed on a flared flange,

wherein the apex angle α of the cone is in a range of about 180°>α≧140°.

2. The flanging machined according to claim 1, wherein that the range is about 180°>α≧160°.

3. The flanging machined according to claim 1, wherein a base area of the flanging role has a diameter d with d≧about 60 mm.

4. The flanging machined according to claim 1, wherein the flanging role is a pre-flanging role.

5. The flanging machined according to claim 1, which comprises an additional flanging role adapted for final-flanging processes, wherein the flanging role has a cylindrical form after the final-flanging processes.

6. The flanging machine according to of the claim 1, wherein the flanging role is adapted for use in pre-flanging and final-flanging processes.

7. A method to spin-flanging workpieces, comprising the steps of:

provisioning of the workpiece to be flanged with a flange on a flanging bed;

pre-flanging of the flange with a pre-flanging role that has a conical form and is guided by a multi-axle manipulator, wherein for the apex angle α of a lateral surface of the cone to be pressed on the flared flange it is in the range of about 180°>α≧140°; and

final-flanging of the flange.

8. The method according to claim 7, wherein the final-flanging is carried out with a final flanging role having a cylindrical form.

9. The method according to claim 7, wherein a local strain caused by the flanging role is at its lowest at the at an edge of the flange and has a gradient from the edge of the flange to a beginning of the flange.

10. The method according to claim 7, wherein the symmetrical axle of the flanging role is oriented in a substantially vertical position relative to a surface of the flanging bed.

11. The method according to claim 10, wherein the symmetrical axle of the flanging role is turned anti-clockwise by a traveling angle β in relation to a vertical of a translational directions.

12. The method according to claim 7, wherein the symmetrical axle of the flanging role is substantially parallel to a surface of the flanging bed.

13. The method according to claim 12, wherein the symmetrical axle of the flanging role is turned clockwise in relation to the vertical of the translational direction v1 by a traveling angle β.

14. The method according to claim 7, wherein the flanging role is guided with a translational velocity v1 during the pre-flanging, and the translational velocity v1 has a range of about 1000 mm/s≦v1≦1600 mm/s.

15. (canceled)