EP1064111B1 - Method for controlling, monitoring and checking a forming operation of a metal-forming machine tool, especially a riveting machine - Google Patents

Description

The present invention relates to a method for Controlling, monitoring and checking a forming process a forming machine, in particular a riveting machine, on one Workpiece by means of a piston, which against the Workpiece is moved, with an upper piston surface and / or a lower piston surface for moving the piston is pressurized and a forming machine to carry out the above Process.

Forming machines, especially riveting machines are in the stand known in the most varied of forms and designs and common. They are primarily used to mechanical mechanical material deformations, in particular also rivets. Such should. Machines can be integrated into automation processes can. Essentially, this is the Production of riveted joints using a riveting machine cold deformations, because two Parts can be connected together.

With an inevitable high level of automation, like it more and more demands is an independent one Checking the degree of deformation, especially the riveting urgently required because of very high requirements Rivet connections are made today. The review and Detection of a faulty riveted joint is therefore absolutely necessary.

EP 0 699 490 A1 describes a device for Verification of material deformations known, being about two different displacement sensor arrangements and via push buttons if necessary, a deviation is determined. The disadvantage here is that such a device is complex and complex manufactured and no exact determination of a rivet start is possible.

Furthermore, DE 37 15 905 C2 describes a method for mechanical production of riveted joints and a riveting machine for performing the method known, at which opposes a striker from a given zero position a workpiece is moved. This shifting to one Workpiece is made with a measuring force that is less than the force required to deform the rivet. The feed distance of the striker caused by the measuring force is measured and is used as an actual value with a setpoint compared. The disadvantage of this is that not with full Feed force can be applied to the rivet. A Monitoring of the complete riveting process is not here possible.

From the publication in Ölhydraulik, Dietmar and Franz Locate Eisen, Springer Verlag 1994, pages 394 to 396 Hydraulic cylinder described as an energy converter by a hydraulic fluid transferred and over Hydraulic energy provided in line connections and transform linear mechanical force and movement for example on the piston rod.

EP 0 549 793 A1 describes a method for plastic deformation of workpieces, the Feed rate of the striker is controllable.

The present invention is based on the object Procedures for controlling, monitoring and reviewing a Forming process and to create a forming machine at which a determination of a start of forming or Rivet start is exactly possible. After that, exact Conclusions about faulty forming processes may be possible. Furthermore, significant manufacturing costs should such a forming machine can be reduced. It is said to be very easy and simple with increasing the forming quality control.

The solution to this task is that when the Piston, especially the striker, on the workpiece of Start of forming, especially start of riveting, by changing the Forming force is determined, this forming force with With the help of a differential pressure measurement through determined pressure in the upper piston chamber minus the determined pressure in the lower Piston space is calculated.

Such a pressure difference in a pressure line and a vent line for moving the piston, or in an upper and a lower piston chamber itself at least one sensor element is measured, determines one exact start of forming when the piston strikes a Workpiece. Due to the direct impact when moving the piston or the rivet head on a workpiece a pressure change, which is immediately in the Sensor element, in particular pressure sensor, recognized and is determined. From a change in pressure, the Change in the force with which the forming takes place, determine and control exactly. A change in strength can also give conclusions about the start of forming.

The sensor element should preferably be in the machine housing provided near the upper and / or lower piston space his. This is connected to a control device, which evaluates the data.

In the present invention, it is also advantageous that the piston permanently with full feed and if necessary constant feed force when forming on the workpiece can be driven. Only the pressure change immediately when the riveting tool hits the Workpiece displayed and can via a distance measuring device then a predefined path, in particular a forming path continue until the predetermined path is reached within a certain time. on the other hand can also with a given feed or forming force the piston against the workpiece for a certain time be moved until after a certain forming or Comparison time, the forming is carried out as desired.

By predetermined comparison parameters, which, for example, by Experiment can be determined, can be exactly determine whether the forming has been carried out as desired. It can be determined exactly, for example, whether the rivet was sufficient or not a rivet at all, or whether the forming time or the forming path was carried out exactly. This is through the Determination of the exact start of forming possible.

Therefore, in the present invention is a method as well as a forming machine, with which very exactly one rivet start or forming start can be determined can. Here, for example, when reshaping a given one Path, the time for a specific forming path as Comparison criterion can be used to make a statement faulty or non-faulty forming receive.

It is also possible that the time is predetermined and the forming path covered during this time as Comparison criterion for determining a forming condition is used. This ensures that too an automated forming process is constantly monitored and can be controlled.

It is also within the scope of the present invention that after determining a start of forming or A predetermined forming path is traversed at the start of the process, with a time comparison and / or a additional comparison of the forming force (effective Force action in Newton N) on the rivet or Workpiece, the unit of time or the force at the moment, in which the specified shape path has been reached Forming process monitored and a forming result determined becomes. This can be done via specified force windows or Time windows happen that shed light on one Give tolerance limit range. It can take time and strength continuously throughout the entire forming process be recorded. The sampling rate can be bpsw. in 100 Hz take place and results in the size of the work performed per unit of time.

Another advantage is that a very precise error detection or a determination of the cause of the error is always preferred by two comparison variables with a given one Parameter is made to rule out two Mistakes together with reverse value each other compensate and thus a detection of an error prevent.

If, for example, a riveted item is faulty and too soft, it would be Riveting time too short with distance covered. The reshaping would be faulty. For example, if there is a pressure loss in the system, for example, the riveting time would be too long due to Lekagen. Kick this For example, if both errors occur simultaneously, both would Remove errors and this could not be recognized. This is eliminated as a comparison criterion preferably always use two comparison variables become. This enables exact error determination. These comparison criteria are not just the end result but also the complete forming process depending on the process variables forming force, forming time, forming path etc. for sure. About the individual parameters such as path, Speed, time and pressure difference can be Forming force and path per unit of time in forming work easily determine.

The determinable forming work per unit of time also leaves an exact assessment of the riveting process and in particular an exact conclusion on the strength properties of the formed workpiece.

Figur 1 einen schematisch dargestellten Teillängsschnitt durch ein Ausführungsbeispiel einer erfindungsgemässen Nietmaschine;

Figur 2 einen schematisch dargestellten Teillängsschnitt durch ein weiteres Ausführungsbeispiel der Nietmaschine gemäss Figur 1.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

1 shows a schematically illustrated partial longitudinal section through an embodiment of a riveting machine according to the invention;

FIG. 2 shows a schematically illustrated partial longitudinal section through a further exemplary embodiment of the riveting machine according to FIG. 1.

In Figure 1 is a forming machine, in particular Riveting machine R shown, the main components a conventional riveting machine, as in the EP 0 699 490 A1 is shown. It is explicitly based on referred to this prior art because essentially there all the components of a conventional riveting machine are described in detail. Another description the individual components are therefore dispensed with.

A forming machine R only has a dashed line here indicated machine frame 1, which only one has indicated vertical support arm, in which preferably adjoins a support surface 2 at right angles. The support surface 2 carries the workpieces to be machined 27. These are not numbered in detail here. To the Machine frame 1 and especially on the vertical Carrying arm is a machine housing 3, which in Interior is hollow. In the machine housing 3 is a preferably hollow slidable pneumatic piston 4 arranged. Protrudes from the piston 4 preferably a projecting flange 5 towards the outside, which is guided in a cavity 6 of the machine housing 3 is. The cavity 6 is through the protruding flange 5 in an upper piston chamber 7 and lower piston chamber 8 divided. The projecting flange 5 accordingly has a upper piston chamber 7 facing upper piston surface 9 and a lower piston surface 10.

One preferably opens into the upper piston chamber 7 pneumatic or hydraulic pressure line 11 a. To the lower piston chamber 8 closes at the bottom pneumatic or hydraulic vent line 12. In the pressure line 11 and vent line 12 is respectively a control valve 13, 14, in particular a throttle, is used, the connecting lines 15.1, 15.2 with a Control device 16 is connected. Another Connection line 15.3 provides the connection between a drive motor 17, in particular an electric motor. This can also be designed as a hydraulic motor. The Electric motor drives a sleeve 18.1 in which changeable a projecting end 18.2 one Drive shaft 19 is mounted. The drive shaft 19 is via only indicated bearings in a cavity 20 of the Piston 4 rotatably mounted. To the drive shaft 19 adjoins a rivet head 21 at the bottom. The rivet head 21 also serves as a tool holder. This can, for example, as Riveting tools include a striker 22.

Furthermore, the preferably fixed machine housing 3, as well as in the machine housing 3 in the direction of a Z axis 23 movable pistons 4, a displacement measuring device 24 which, via a further connecting line 15.4 the control device 16 is connected. This Control device 16 takes over all regulations and Controls that operate the R required are.

The data required for this can be obtained via a Computer 25 entered and during or after a Work process evaluated and output there. This is only an example here. In particular, can such a control device 16 into an existing one Production can be integrated in order to be fully automatic to operate the corresponding riveting machine R.

It is essential in the present invention, however, that as indicated schematically in Fig. 1, a Sensor element 26.1 in the pressure line 11 and Sensor element 26.2 inserted into the vent line 12 is. The sensor elements 26.1, 26.2 are preferably close of the machine housing 3 in the pressure line 11 or Vent line 12 used. The sensor elements 26.1, 26.2 are also via connecting lines 15.5, 15.6 connected to the control device 16. It is important here also that the sensor elements 26.1, 26.2 between the Control valves 13, 14 and the machine housing 3 in the Pressure line 26.1 or vent line 26.2 used are.

The sensor elements 26.1, 26.2, which are preferably as Pressure sensors, but also designed as a pressure transmitter are a very precise change in pressure in the Determine pressure line 11 or vent line 12 if when moving the piston 4 to a machined Workpiece 27 strikes. Immediately upon hitting the Workpiece 27, for example on a rivet, is in the pressure line 11 causes a pressure change that is beyond the Sensor elements 26.1, 26.2 and accordingly in the Vent line 26.2 is registered immediately. This Pressure change causes a start or an Displacement of the zero point can be calculated. The exact determination of the start of the rivet is required in order to for the optimum forming process, the exact forming path required to be able to determine. If the start of the rivet is known, it can via further method via the path measuring device 24 Forming path can be determined exactly. This can also be done by continuous procedure and timing can be possible. The advantage here is that an exact determination of the Forming begins by changing the pressure in the Sensor elements 26.1, 26.2 can be detected.

In a further embodiment of the present invention according to 2 shows a forming machine R ₁ , in particular a riveting machine, in which the sensor elements 26.3, 26.4 are inserted into an upper piston chamber 7 and a lower piston chamber 8. A throttle valve 29, which is adjustable, is preferably inserted into the vent line 12. This can be connected to the control device 16. As a result, the movement of the piston 4 can be damped in particular into a lower position. A hard impact of the piston after the downward movement is prevented by this throttle valve 29. Furthermore, the spindle advance can be regulated by means of the throttle valve 29, it also being possible to change the speed of the travel path of the spindle or of the piston 4.

The sensor elements 26.3, 26.4 are over the Connection lines 15.7, 15.8 with the control device 16 connected. Here, too, can be determined exactly if by Pressure change of the rivet head 21 with riveting tool, for example Dropper 22 strikes a workpiece 27. Through the Not only the change in pressure can precisely determine the start of the rivet but also the one calculated from the pressure change Forming force. By determining the start of the rivet or Forming start, which is equivalent to a Process start, either the riveting time or the path are specified, the riveting results can be exactly check and determine.

If, for example, the forming path is known or specified, then through additional time comparison influence on the quality of the forming process. Will be within one certain time a certain predetermined way the reshaping or riveting is completed successful. So that a comparison is possible, for example Trial determined a certain time, a time tolerance measure set to a positive or negative riveting result detect.

Furthermore, even after the exact determination of the Rivet start a predetermined time for forming or riveting be specified, with the path traveled as Comparison parameter is used to get a riveting result to judge. The path can be followed via the Determine the path measuring unit exactly, however Trial or by a certain specification a path tolerance stipulated which as a comparison tolerance measure for a successful reshaping.

Is when riveting or forming after a predetermined time the path tolerance is not adhered to, this leaves one Conclusion of an error in the forming process. It can have several causes, e.g. the rivet is too long, the workpiece is too thick or material wear is too high. There may also be material defects. Through the Specification of time or path tolerance window through Experiments can be determined, and using software to Can be used for comparison exact determination of the riveting process and in particular one Determine the forming result of the workpiece. in the the exact determination of the Start of riveting by recording and determining the Change in pressure and / or change in force. So it can Pressure change as a pressure difference from the pressure in the upper one Piston chamber with regard to the pressure in the lower piston chamber be determined. Therefore, especially with riveting machines, which after a wobble process or radial process work, always an exact determination of the start of the rivet possible.

This leads to a reduction in rejects and an increase in Precision of a riveted joint and at the same time Detection of defective workpieces that are not the Meet requirements.

Position Number List

1 machine frame 34 67 2 bearing surface 35 68 3 machine housing 36 69 4 piston 37 70 5 flange 38 71 6 cavity 39 72 7 upper piston chamber 40 73 8th lower piston chamber 41 74 9 upper piston surface 42 75 10 lower piston surface 43 76 11 pressure line 44 77 12 vent line 45 78 13 control valve 46 79 14 control valve 47 15 connecting line 48 16 control device 49 17 drive motor 50 18.1 shell 51 18.2 The End 52 R Forming machine riveting machine 19 drive shaft 53 R ₁ Forming machine riveting machine 20 cavity 54 21 rivet head 55 22 Döpper 56 23 Z-axis 57 24 displacement measuring system 58 25 computer 59 26 sensor element 60 27 workpiece 61 29 throttle valve 62 30 63 31 64 32 65 33 66

Claims (19)

1. Method of controlling, monitoring and checking a reshaping process of a reshaping machine, more especially a riveting machine (R), on a workpiece (27) by means of a piston (4), which is displaced towards the workpiece (27), an upper piston face (9) and/or a lower piston face (10) being acted upon with pressure to displace the piston (4), characterised in that, when the piston (4) or, more especially, the riveting set (22) encounters the workpiece (27), the beginning of the reshaping, more especially the beginning of the riveting, is determined by the change in the reshaping force, this reshaping force being calculated by means of a device for measuring the differential pressure by the pressure detected in the upper piston chamber (7) minus the pressure detected in the lower piston chamber (8).
2. Method according to claim 1, characterised in that a reshaping force is calculated and/or indicated during the entire reshaping process by means of a device for measuring the differential pressure by the pressure detected in the upper piston chamber (7) minus the pressure detected in the lower piston chamber (8).
3. Method according to claim 1 or 2, characterised in that the pressures in the upper and lower piston chambers (7, 8) are measured directly in the upper and lower piston chambers (7, 8).
4. Method according to claim 1, characterised in that the pressures in the upper and lower piston chambers are measured directly in a pressure line (11) and a ventilation line (12).
5. Method according to at least one of claims 1 to 4, characterised in that the pressures in the upper and lower piston chambers are detected with at least one sensor element (26.1 to 26.4).
6. Method according to at least one of claims 1 to 5, characterised in that the beginning of the reshaping path and/or the beginning of the reshaping time are/is detected by detecting the changes in the force and by determining the beginning of the reshaping.
7. Method according to claim 6, characterised in that a zero point is displaced to a workpiece start by detecting the beginning of the reshaping.
8. Method according to claim 7, characterised in that the deformation is determined by the displacement and detection of the zero point as the beginning of the reshaping over a predeterminable period and/or a predeterminable reshaping path and/or a predeterminable reshaping force.
9. Method according to claim 8, characterised in that any possible defective reshaping, more especially riveting, is detected by a deviation from the predetermined parameters or relationships between these parameters, such as the beginning of the reshaping, the reshaping time or the reshaping force per reshaping path.
10. Method according to at least one of claims 5 to 9, characterised in that a prescribed reshaping path is displaced after determining the beginning of the reshaping or respectively the beginning of the process, and any possible defective reshaping is determined by a time comparison.
11. Method according to at least one of claims 5 to 10, characterised in that a displaced path is detected as a comparison parameter for determining any possible defective reshaping, possibly in the path tolerance range, after determining a beginning of the reshaping or respectively the beginning of a process over a prescribed time.
12. Method according to at least one of claims 5 to 11, characterised in that a force window is detected as a comparison parameter for determining any possible defective reshaping, possibly in the force tolerance range, after determining a beginning of the reshaping or respectively a beginning of the process over a prescribed path.
13. Method according to at least one of claims 5 to 12, characterised in that, after determining a beginning of the reshaping, the reshaping work, possibly the reshaping work per unit of time, is detected as a comparison parameter for determining a defective reshaping, possibly in the work tolerance range.
14. Reshaping machine, more especially a riveting machine, having a piston (4) which is displaceable in a Z-axis (23) and which is displaceably guided with pressure towards a workpiece (27) in a machine housing (3), and the piston (4), more especially the flange (5) thereof, is displaceable in a cavity (6), which is divided into an upper piston chamber (7) and a lower piston chamber (8), a pressure line (11) terminating in the upper piston chamber (7), and a ventilation line (12) terminating in the lower piston chamber (8), characterised in that at least one sensor element (26.1 to 26.4) is respectively associated with each line (11, 12) and/or with each piston chamber (7, 8) for detecting a differential pressure and/or a change in the force when the piston (4), more especially the riveting set (22), encounters a workpiece (27), by means of which sensor elements a pressure difference between the pressures in the pressure line (11) and in the ventilation line (12) and/or between the pressures in the upper piston chamber (7) and the lower piston chamber (8) is determinable.
15. Reshaping machine according to claim 14, characterised in that at least one sensor element (26.1 to 26.4) is associated with at least each line (11, 12) for detecting a pressure difference and/or change in the force and/or change in the reshaping work, possibly per unit of time.
16. Reshaping machine according to claim 14 or 15, characterised in that at least one sensor element (26.1 to 26.4) is provided in the pressure line (11), an additional sensor element is provided in the ventilation line (12) and/or in the upper piston chamber (7), and an additional sensor element is provided in the lower piston chamber (8), for determining a pressure difference and or change in the force when the piston (4) encounters a workpiece (27).
17. Reshaping machine according to at least one of claims 14 to 16, characterised in that the at least one sensor element (26.1, 26.2) is provided in each line (11, 12) between a control valve (13, 14) and the piston chamber (7, 8), in proximity to the latter.
18. Reshaping machine according to at least one of claims 14 to 17, characterised in that the sensor elements (26.1 to 26.4) are connected to a control apparatus (16).
19. Reshaping machine according to at least one of claims 14 to 18, characterised in that the piston (4) is axially displaceable along a Z-axis (23).

Images