EP1927404A2 - Method for determining spray parameters for controlling a paint gun using a spray agent - Google Patents

Abstract

The invention relates to a method for determining spraying parameters for controlling a spraying means employing painting, which is moved over a surface to be painted, in particular a robot with a Lackierapplikation. A known spray pattern is provided with known spray parameters and paint quantity for a given movement speed of the paint sprayer, and a paint quantity is adjusted to a new movement speed in comparison to the predetermined movement speed. In addition, new spray parameters are calculated while maintaining a similar to the known spray pattern spray pattern on the adjusted amount of paint.

Description

The invention relates to a method for determining spraying parameters for controlling a spraying means employing painting, which is moved over a surface to be painted, in particular a robot with a Lackierapplikation.

It is well known that in industrial coating technology painting equipment, in particular paint sprayers, such as high-rotation atomizers or air atomizers are mounted on manipulators, in particular robots, and perform during the painting process with activated paint atomizer movement over the object to be painted. The aim of a painting process is to cover the object to be painted in a desired layer thickness as homogeneously as possible with varnish. If the homogeneity of the layer thickness is not given, there is the risk of visual errors or the risk of runners, or cookers on the object to be painted. This is to be avoided for quality reasons.

Frequently, the paint atomizers are moved in meandering paths over the object to be painted so as to gradually cover the entire surface with paint.

Here, ever higher speeds of movement of the paint sprayer are required to complete the painting process as quickly as possible. On the other hand, the speed of the paint sprayer at the reversal points is almost zero, so that the sputtering conditions on the paint sprayer must also be adapted to this movement speed change.

So far, this adjustment of the outflow of the paint material, especially in the area of inflection points, by reducing the paint material, or the atomizer is temporarily switched off completely. For the reduction of the paint material, additional switching points are defined during the programming on the movement path, which, when reached, switches over to a parameter set of spray parameters for the coating device that corresponds to the new movement speed. Such a parameter set has previously been determined in advance by experiments on a case-by-case basis and made available to the painting system in a so-called brush table. Such a parameter set covers a certain speed range of the painting device, since there is no mathematically linear relationship between the movement speed and the discharge quantity.

Based on this prior art, it is an object of the invention to provide a method for determining spraying parameters for controlling a painting device employing spraying, which simplifies the finding of spraying parameters.

This object is achieved by the method for determining spray parameters for controlling a spraying paint applicator, which is moved over a surface to be painted, with the features specified in claim 1.

Accordingly, the method according to the invention for determining spray parameters for controlling a painting device which starts spraying and which is moved over a surface to be painted, in particular a robot with a painting application, has the following method steps. A known spray pattern is provided with known spray parameters and paint quantity for a given speed of movement of the paint sprayer. An amount of paint is adjusted to a new speed of movement compared to the predetermined speed of movement.

In addition, new spray parameters are calculated while maintaining a similar to the known spray pattern spray pattern on the adjusted amount of paint.

In this way, it is achieved that the attempts which have since been made to determine a parameter set can be completely eliminated. In addition, the spray parameters can be calculated at any speed or speed change so that, if necessary, the speed ranges for a parameter set to control a spray can be chosen to be correspondingly smaller. The painting result is improved accordingly.

A further development of the method according to the invention is characterized in that, starting from the known spray pattern, a preliminary spray pattern is calculated using the known spray parameters and new paint quantities, that the known spray parameters are changed in order to obtain modified spray parameters which result in a further spray pattern changed spray parameters are changed until the next spray pattern is similar to the known spray pattern within a similarity criterion, and that the changed spray parameters, which are similar to the known spray pattern, are provided as new spray parameters.

In this way, the calculation of the new spray parameters under a similarity aspect of the spray images is particularly easily calculated. The implementation, as the similarity criterion is or how the new spray parameters are to be obtained in detail, have already become known. Further details about finding similar spray patterns have already become known to those skilled in the art.

An advantageous embodiment of the method according to the invention also provides that the spray parameters include the control of a plurality of air streams, which influence the spray behavior of the Lackiergerätes.

In this way, additional parameters for controlling, for example, a steering air or limiting air flow are included. Overall, the paintwork becomes more effective and overall the process is improved.

In addition, it is provided according to the invention that, in the case of deviations of the new movement speed from the predetermined movement speed, which result in a preliminary spray pattern which is similar within a similarity criterion, the known spray parameters are used.

In this way, the computational effort for calculating the spray parameters can be particularly easily limited. If the coating results show that the coating quality meets the quality requirements within a certain range of movement speed, the similarity criterion determines in which area the existing or currently used spray parameters are used. When exceeding or falling below this range, the spray parameters are recalculated accordingly and the parameter set is changed accordingly.

In addition, it is advantageous if the new spray parameters are calculated during the operation of the paint sprayer and before the change in the predetermined speed of movement is performed.

This can be done either by the robot controller itself or by an external computer, which then provides the calculated data to the robot controller. In any event, an advantage of this embodiment is that the spray parameters are calculated so quickly that they are calculated just prior to the execution of a modified move speed without the need for a file or table to be provided to the system prior to execution of the move program. Of course, it is also within the inventive concept that the calculation of the spray parameters is performed first before the operation of the robot begins. These data of the spray parameters are then collected in a so-called "look-up" table and optionally stored, for example for all variants for all spray conditions (brushers).
The look-up table is provided to the robot controller, so that no additional calculation is necessary before a spray parameter change, but the data is taken from the look-up table.

Further advantageous embodiments of the subject invention can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, its advantages, and other improvements of the invention will be explained and described in detail.

Fig. 1

eine Darstellung einer Schichtdickenverteilung,

Fig. 2

einen schematischen Verfahrensablauf sowie

Fig. 3

ein weiteres Schema von Funktionszusammenhängen bei der Sprühparameterermittlung.

Show it:

Fig. 1

a representation of a layer thickness distribution,

Fig. 2

a schematic procedure as well

Fig. 3

another scheme of functional relationships in the spray parameter determination.

Fig. 1 shows an image 10 as a plan view of a painted surface, in which different layer thicknesses of the paint through different areas 12 are shown. This representation can be colored, or represented by area boundaries in the form of lines. In addition, the figure still shows a meandering line 14, which represents a trajectory of a Lackierapplikation on a robot arm. The painting has begun at a starting point 16 and has been moved by reciprocating movements under advancement perpendicular to the reciprocating motion at the respective beginning and end of each reciprocating motion gradually over a previously determined area, so that the Lackierapplikation finally arrives at an endpoint 18.

This figure is intended to illustrate the different speeds and accelerations during a painting movement. First of all, the painting application has to be accelerated from the start to a constant working speed starting from starting point 16 in order to achieve a uniform painting result. Towards the end of the movement, in extreme cases, the speed drops to almost zero at one point of the path of the painting application, and at the exit of the curve it returns to the opposite direction to the predetermined setpoint speed to accelerate. Accordingly, the complete meander is run through until the end point 18 is reached.

In any case, at the various speeds, it is also necessary to adjust the quantity of paint at the respective speed, so that a desired layer thickness of the paint is achieved at every point on the painted surface. Only then is it guaranteed that the coating has a consistent surface and thus achieves the appropriate quality. That is, the higher the travel speed, the more paint must be delivered through the paint application to achieve a comparable average film thickness, as compared to a slower speed with a correspondingly smaller paint amount.

Fig. 2 shows a schematic flow diagram of the method according to the invention, with the spray parameters for controlling the spray for example, the paint application can be determined in a particularly simple manner. First, the starting conditions for the inventive method for determining spray parameters are determined. This is done by a first method step 24, with which basic data for the method are read from a so-called brush file. The file contains all essential for the painting spray parameters for controlling a spray, here the paint. Accordingly, all the process data, such as the outflow quantity, the paint color, etc., are determined by the brush file, so that the determination will set a specific spray pattern when using a coating device.

In a second method step 26, it is determined that the following method steps are carried out for each movement speed of the varnishing device until a termination criterion is reached.

First, in a third method step 28, a simulation of the original spray pattern is carried out for a specific movement speed, wherein the data associated with the movement speed are referred to as a single brush. The original spray pattern is that spray pattern which, at a given setpoint speed and associated assigned spray parameters, such as Lackausflussmenge, Lenu air data, etc., results. This spray pattern is made available as a known spray pattern with known spray parameters for the further course of the process.

In a fourth method step 30, an outflow quantity is then adapted to a new movement speed and from this a new spray pattern is derived or calculated, wherein further boundary conditions such as solids content, layer thickness or efficiency etc. are considered known or calculated under certain assumptions.

In a fifth method step 32, the rotational speed or the atomizing air is adapted and calculated. In a sixth method step 34, the calculation of a so-called horn or draft air takes place. Here, horn air are used together with atomizing air in a Luftzerstäuber as a control variable and Lenkluft together with speed in the rotary atomizer. In this case, an increase in the spray pattern width in the air atomizer by an increase in the horn air or the rotary atomizer by a reduction of the shaping air. In this way, the width of the spray pattern can be adapted to that of the original known spray pattern.

In a further method step, the seventh method step 36, the efficiency is calculated as a measure of the similarity of the original spray pattern with the newly calculated spray pattern, in order to iteratively correct the assumed efficiency of the new spray pattern, if necessary. If sufficient similarity has not yet been achieved, or if the efficiency has changed, the method steps are repeated as of the fourth method step 30, which should be symbolized by the arrow 40, until sufficient similarity of the spray patterns is achieved and any differences in efficiency are corrected iteratively ,

Thus, in a ninth method step 42, the calculation of so-called color subclasses can follow with an increased or reduced outflow quantity as appropriate. In this way, the inventive method has calculated a new record for the so-called brush file, which is similar to the original spray pattern new Produce spray on the paint sprayer, which is due to the new discharge rate or the new speed of movement of the paint. This data is described in a tenth method step 44 in an updated brush file. In this way, the spraying parameters for controlling the painting device are determined and can be used, for example, by the painting device.

Fig. 3 shows a further scheme 50, which shows the data flow in an application of the method according to the invention for a painting robot with a Lackierapplikation. The example chosen in this figure is based on a robot carrying an application 52, for example a rotary atomizer with electrostatic charge. The robot has a robot control 54, which contains as input data by a motion program 56, which specifies the coordinates of the individual points, the orientation of the individual points, a specification of the desired speed and application parameters and switching points.
In addition, the robot controller 54 is aware of a kinematic model of the robot 58, which ultimately calculates the previous calculation of the coordinates and the velocity associated with the coordinates of the robot, in particular each part of the robot arm, and the kinematic model for all future times on a trajectory of the robot can be, or are known about the corresponding models. In particular, for the painting in connection with the method according to the invention, the specification of the desired speed in each track point is an essential variable.

Namely, if a comparison 60 of the target speed is detected in a path point with the actual speed in this path point, which is greater than a predetermined differential speed, according to the inventive method in a corresponding method step 62, a correction time TK and the speed deviation (difference) at time TK certainly. In a follow-up method step 64, the correction of the application parameters while maintaining the spray pattern geometry as well as the transfer of the parameters to the application at the time TK are then to be carried out. In this way, the application 52 receives a new instruction at the time TK, which then corresponds to the new speed, so that the spray pattern geometry also changes with a changed new speed Spraying process is maintained and thus a correspondingly high quality of the paint is achieved.

If, in the comparison 60, the deviation of the setpoint speed from the existing actual speed at the time TK is smaller than the permitted differential speed, in an alternative method step 64 only the previously known parameters for the application series 50 are confirmed, so that no correction of these parameters must take place. Either the parameters remain valid beyond the time TK for the application or an identical sentence is transferred to the application at the time TK, so that they continue to work as a result in any case with the known parameters. However, this is a data engineering standard procedure, and has no significant effect on the inventive method.

LIST OF REFERENCE NUMBERS

10

image

12

different areas

14

line

16

starting point

18

endpoint

20

turning point

22

flow chart

24

first process step

26

second process step

28

third process step

30

fourth process step

32

fifth process step

34

sixth process step

36

seventh process step

38

eighth process step

40

arrow

42

ninth process step

44

tenth process step

50

another scheme

52

application

54

robot control

56

exercise program

58

kinematic model

60

comparison

62

step

64

Subsequent step of the procedure

Claims (10)

Method for determining spraying parameters for controlling a spraying device using paint, which is moved over a surface to be painted, in particular a robot with a Lackierapplikation, wherein a known spray pattern with known spraying parameters and amounts of paint for a given speed of movement of the Lackiergeräts is provided, wherein a paint amount a new movement speed compared to the predetermined movement speed is adjusted, and wherein new spray parameters are calculated while maintaining a similar to the known spray pattern spray pattern on the adjusted amount of paint. A method according to claim 1, characterized in that the movement speed or the speed change is provided as a default value for a real speed of a robot controller (54). A method according to claim 1 or 2, characterized in that starting from the known spray pattern a preliminary spray pattern is calculated using the known spray parameters and new paint amount that the known spray parameters are changed to obtain modified spray parameters, which give a further spray pattern that the changed spray parameters are changed until the further spray pattern is similar to the known spray pattern within a similarity criterion, and the changed spray parameters similar to the known spray pattern are provided as new spray parameters. Method according to one of the preceding claims, characterized in that the spray parameters are suitable for controlling a plurality of air streams, which spray parameters influence the spray behavior of the paint sprayer. Method according to one of the preceding claims, characterized in that in the case of deviations of the new movement speed from the predetermined movement speed, which result in a preliminary spray pattern which is similar within the similarity criterion, the known spray parameters are used. Method according to one of the preceding claims, characterized in that the new spray parameters are calculated during the execution of the operation of the Lackiergerätes and before the execution of the change in the predetermined speed of movement. Method according to one of claims 1 to 15, characterized in that the new spray parameters are calculated prior to the execution of the operation of the Lackiergerätes. Method according to one of the preceding claims, characterized in that the calculation of the new spray parameters takes into account the expected layer thickness distribution after a change. Method according to one of the preceding claims, characterized in that the calculations are performed by the robot controller (54) or by a cooperating with the robot controller (54) data processing system. Method according to one of the preceding claims, characterized in that each new spray parameters are determined and stored for a number of speed ranges or speeds.

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