EP2998029B1 - Method for the automated application of a viscous or fluid medium onto components and dosing device for carrying out the method - Google Patents

Description

The invention relates to a method for the automated application of a viscous or liquid medium to components, in particular body components of a motor vehicle, in which a metering device which comprises at least one metering chamber containing the medium, an outlet valve and a displacer connected to a positive displacement drive for compressing and conveying the medium the metering chamber, and the component are moved relative to each other at a feed rate to apply the medium along a predetermined path and with a defined order pattern on the component, and a controller connected to the metering device, the volume flow and the outlet pressure of the medium by actuation of the exhaust valve and the displacement drive controls.

The invention further relates to a metering device for carrying out the method, at least comprising a metering chamber containing the medium, an outlet valve, an electrically driven displacer for compressing and conveying the medium in the metering chamber and a controller for actuating the outlet valve and the displacer drive as a function of the required Volume flow and outlet pressure of the medium.

From the DE 37 00 212 A1 A method for the metered application of an adhesive is already known, in which the adhesive is applied by means of a movable robot arm in defined paths. For this purpose, a metering device has a hydraulically driven piston which is displaced in a cylinder filled with the adhesive and thus presses the adhesive out by displacement. In this case, the hydraulic pressure is kept constant at a certain value, which is adapted to the feed rate of the robot arm. In the opening phase of the exhaust valve, the hydraulic pressure for driving the piston is adapted to a constant feed rate of the dosing device, which, however, does not usually coincide with the actual feed rate. Furthermore, system changes, such as non-constant viscosity of the adhesive, lead to irregularities in the amount of discharge / time. As a result, with increasing viscosity, the adhesive sheet is thinner and may even have interruptions by demolition, while at sinking viscosity too much adhesive leaks. Consequently, no constant dosage is achieved. Furthermore, difficulties also occur in the opening phase of the exhaust valve. The hydraulic pressure for driving the piston is in fact also adapted at this moment to a constant feed rate, which, however, does not generally coincide with the actual feed rate. In order to ensure a constant metering of the adhesive under all operating conditions, a control is carried out with an automatic adjustment of the displacement speed of the piston to the respective present system sizes. For this purpose, a value of the discharge speed adjusted as a function of the discharge amount / time is generated as the desired value, compared with an actual value of the discharge rate corresponding to the displacement speed of the piston, and the output value for the displacement speed of the piston is controlled. As a result of this control, an automatic adaptation of the displacement speed of the piston to the respectively present system variables takes place, as a result of which constant metering is achieved. It is particularly advantageous for the opening phase of the exhaust valve, if before the opening of the exhaust valve, a feed rate depending on the discharge / time adapted value of the pending on the outlet valve pressure of the medium is generated as the setpoint and with the actual present at the outlet valve actual value of the pressure is compared and the output value controls the pressure generated by the piston on the adhesive. As a result, the desired discharge rate is ensured even at the beginning of the discharge.

Furthermore, from the DE 10 2008 018 881 A1 a method and a device for applying a viscous material, in particular an adhesive or sealant, known on a workpiece, with a job valve having an application device and a robot carrying the applicator. By means of a control unit, the speed of the application device relative to the workpiece is detected in order to calculate the times at which the order valve is to be opened and closed in order to obtain the desired material beads. The aim is to decouple the control of the robot and the control of the opening and closing operation of the application valve, because the signal transmission from the robot control unit to the order valve is not deterministic, that does not take place with the desired temporal accuracy. The switching time of the application valve, which elapses from its actuation until it is opened or until it closes, expediently flows into the calculation of the opening and closing times. In this case, a predetermined switching time can be stored in the data memory of the valve control unit. If the switching time of the application valve of the valve control unit is known, it can start the opening or closing operation earlier by the appropriate time, ie be controlled in advance, so that even after prolonged operation, the material caterpillars and their distances from one another can be obtained in the desired accuracy. A more precise measurement of the opening and closing behavior of the application valve is obtained when the position of the needle is measured at predetermined, short time intervals or continuously with an analogue sensor.

Furthermore, for example, from the DE 42 17 835 A1 a state-oriented control for adhesive application systems with a robot known, the computer-controlled along the predetermined caterpillar track moves off the workpiece. The robot arm does not move at a constant target speed, but achieves relatively high speeds in straight sections and brakes against major changes in direction. Depending on the desired thickness of the bead and the speed of the robot at the respective location of the track, a certain volume of fluid per unit time must emerge from the metering. A control computer calculates at each point of the track from the target thickness of the bead and the instantaneous relative speed between the metering nozzle and workpiece a target pressure of the fluid in the derivative. If the actual pressure of the fluid measured with the pressure sensor deviates from this desired pressure, the control computer effects an adjustment of the stepping motor and thus the position of the valve needle, by which the outlet cross section of the metering nozzle and thus the volume flow is changed so as to counteract the deviation long, until the deviation disappears. In addition, the control computer uses in addition to the actual pressure of the fluid and the instantaneous relative speed between the metering and the workpiece and the current temperature of the applied Fuids at each point of the track for an accurate determination of the applied caterpillar.
Thus, the valve can be quickly brought at any point of the track initially in a position that comes very close to the correct position. The correct position is then found using the feedback pressure control. By this default only very small deviations occur.

Another controllable metering device is from the DE 20 2009 013 146 U1 in which the degree of opening of the valve is dependent on the kinematic data of the valve relative to a surface to which the fluid is applied, or depending on material properties of the fluid by moving the valve needle by means of a controlled drive.

A disadvantage is found in the prior art, the high regulatory effort associated with the precise and automated adjustment of the material flow to the existing Conditions and requirements. In particular, control-related time delays can not be ruled out until the desired actual state is reached or, in principle, can not be avoided by the feedback and the subsequent evaluation of the results.

Against this background, the present invention seeks to provide a method of the type mentioned above, with which an even more precise and precise timing of the parameters on the prevailing conditions and the requirements imposed on the volume flow of the material to be applied is possible. Furthermore, a device for carrying out the method according to the invention is to be created.

The first object is achieved by a method according to the features of claim 1. The subclaims relate to particularly expedient developments of the invention.

According to the invention, a method for automated application of a viscous or liquid medium to components is provided in which the material properties of the medium detected in the metering and the measurement results are fed to the controller, which evaluates the measurement results and taking into account stored records for the intended path and the Application pattern of the medium, the required volumetric flow and Auslassdruckwerten calculated and operated in dependence of the determined values and taking into account a temporal pre-offset of the control signals, the exhaust valve and designed as an electric drive displacement drive.

Thus, by analyzing the material properties of the medium already in the metering device in such a way that the flow behavior can be calculated and predicted accurately when applied to the component, feedback and verification of the result according to the prior art arrangements becomes superfluous - instead, exactly what is required Flow rate and outlet pressure guaranteed at each operating time, which corresponds to the measured medium parameters, so that a deviation is excluded from the outset and therefore does not need to be checked. For this purpose, the measurement results regarding the material properties of the medium are compared with the data previously programmed into the control unit with respect to the relative trajectory between the component and the outlet valve and the desired application pattern of the medium and the volume flow and outlet pressure required for the execution calculated automatically. In order to actuate the outlet valve and the displacer drive with pinpoint accuracy on the basis of the determined parameters, the control signals are transmitted to the actuators already before the timestep of the time corresponding to the calculated parameters is reached in order to compensate for the time delays, for example, caused by the signal transmission. Thus, it is possible to apply the medium to the component in a particularly exact time, precisely defined and optimally adapted to the flow behavior of the medium. Furthermore, previously required control loops are basically dispensable.

The provision of the calculated volume flow takes place primarily via the generation of a specific outlet pressure at the outlet valve by means of the displacer arranged in the metering chamber. For this purpose, the medium is first filled into the metering chamber in the case of a preferably closed outlet valve and, with the outlet valve closed, compressed in the moving displacer relative to the metering chamber, which increases or decreases the chamber volume depending on the direction of movement in the chamber. For this purpose, the displacer is driven by an electric displacement drive, which has significant advantages in terms of time accuracy and reaction rate over hydraulic or pneumatic drive devices. As soon as the displacer has reached its predetermined position in the metering chamber, which corresponds to the calculated outlet pressure, the outlet valve is opened and the medium flows at the desired volume flow and without time delays which otherwise occur in the previously known methods when the outlet pressure is too low can, on the component. It should be emphasized at this point that the volume flow is thus not regulated only after the start of the order and initial order errors are therefore accepted, but the material and flow properties of the medium flow into the calculation of the outlet pressure so accurately by the previous detection and evaluation that neither too much still too little medium per unit time flows on the component.

In order to maintain the outlet pressure present at the outlet valve during application, in a preferred embodiment of the method, the displacer should be tracked at a constant rate calculated by the controller to push the medium out of the metering chamber smoothly and without pressure fluctuations. The movement of the displacer is interrupted or stopped by switching off the displacer drive, shortly before the outlet valve is closed, so that no undesired drops of the medium reach the component. With this Embodiment variant is thus a clean completion of the order pattern on the component allows.

According to the invention, the intended application pattern of the medium on the component is taken into account in the calculation of the required volume flow and outlet pressure. This means that variables such as the desired and, for example, also continuously variable thickness and height of the track of the medium on the component and also possible track interruptions, track curvatures and applications or any other pattern of the medium to be realized on the component are entered into the control database and from this In connection with the property values of the medium and with the described temporal pre-offset, the required control signals for the outlet valve and the displacer drive can be determined.

The method described is particularly suitable for applications in which the medium is an adhesion or sealing medium. For these cases, it is of great importance to apply the medium exactly in the predetermined shape and the precisely defined course to the component, since in such deviations, the connection or sealing properties of the component may not be guaranteed under certain circumstances. Furthermore, in particular, adhesion and sealing media often differ in their specific material and flow properties, especially since these media often have significantly temperature-dependent properties, so that only in the metering occurring determination of the nature of the medium allows the exact pre-adjustment of the metering device.

An even more precise embodiment of the method results if the material properties of the medium are recorded repeatedly, preferably cyclically or constantly in the metering device. This ensures that, for example, temperature fluctuations within the metering chamber, which can also cause a change in the flow properties of the medium, are detected and a recalculation of the required volume flow and outlet pressure takes place. Thus, the accuracy of the required parameters can be maintained throughout the application process.

As practical, it has proven to be considered as the material properties of the medium, at least its viscosity, temperature, density and / or chemical composition. Based on these values, a reliable statement about the expected flow behavior of the medium can already be derived, so that the required volume flow and the required outlet pressure can be sufficiently calculated from these measurement results. In addition, these values are generally readily available and need not be recorded separately. Rather, only the drive torque and corresponding time values are detected by the controller.

As already described, the calculated control signals should be supplied with a temporal pre-offset in order to arrive at the exactly required point in time at the actuators, that is to say the outlet valve and the displacer drive. For this purpose, a time offset between the generation of the control signal and the actual actuation of the exhaust valve and the displacement drive is programmed. In this way, the usual control-related time delays can be compensated, so that the temporal accuracy of, for example, the order start, end or a steady change of the order pattern is optimized.

In a likewise very effective embodiment of the method, the displacement drive is controlled with a required increase in the volume flow such that initially a higher compression of the medium takes place in the metering chamber than is necessary for the calculated volume flow. Subsequently, the compression capacity is again reduced, so that the outlet pressure required for the desired volume flow is then present at the outlet valve. As a result of this procedure, as the corresponding tests have shown, the required outlet pressure can be reached faster, despite the upstream pressure boosting step, than with a steady pressure increase. Thus, even quick changes between a job phase and a non-job phase, so for example small interruptions of the job pattern on the component, easily be realized.

Likewise, it has been found that with a required reduction of the volume flow of the medium is not about a reverse direction of movement of the displacer with a corresponding increase in the chamber volume to reduce the outlet pressure appropriate, but rather a time interruption of the movement of the displacer a more accurate and faster adjustment of the outlet pressure allows. For this purpose, the controller generates a corresponding switch-off signal for the displacer drive and after a predetermined, calculated according to the desired reduction of the volume flow time unit a turn-on signal for the positive displacement drive.

The second object is achieved with a device for carrying out the method according to the invention.

Fig. 1

eine erfindungsgemäße Dosiervorrichtung während eines Auftragsvorganges des Verfahrens;

Fig. 2

die erfindungsgemäße Dosiervorrichtung aus Figur 1 während eines Füllvorganges des Verfahrens.

The invention allows numerous embodiments. To further clarify its basic principle, one of them is shown in the drawing and will be described below. This shows in

Fig. 1

a metering device according to the invention during an application process of the method;

Fig. 2

the metering device according to the invention FIG. 1 during a filling process of the method.

The inventive method is described below with reference to the Figures 1 and 2 explained. FIG. 1 shows an embodiment of the metering device 3 according to the invention during the application of a viscous medium 1, here an adhesion medium for connection purposes, on a component surface 2 of a body component of a motor vehicle not shown. The metering device 3 comprises an inlet valve 8 for the supply of the medium 1, a metering chamber 4 containing the medium 1, an outlet valve 5 for a defined discharge of the medium 1 and a nozzle 9 for concentrating the volume flow of the medium 1. In the metering chamber 4 protrudes Furthermore, a displacer 6 in which is connected to a positive displacement drive 7 and according to the arrows 10, 11 experiences a downward or upward movement in the metering chamber 4. According to the invention, a measuring device 12 is further arranged in the metering device 3, in the example shown in the metering chamber 4. The measuring device 12 constantly detects the material properties of the medium 1 contained in the dosing chamber 4, in particular the temperature, density and viscosity thereof, and sends the measurement results to a controller (not shown) for evaluation and calculation of the flow behavior of the medium 1.

Before the application process, the dosing chamber 4 is in a filling process as in FIG. 2 shown filled with the medium 1. For this purpose, the inlet valve 8 is opened and the displacer 6 makes an upward movement according to arrow 11 in the metering chamber 4. The outlet valve 5 is closed during the filling process. After completion of the filling process, the inlet valve 8 is closed and the displacer drive 7 is operated by the controller so that the displacer 6 performs a downward movement to a defined point and thus the medium 1 in the metering chamber 4 to one of the control based on the determined flow behavior of the medium 1 computed pressure value.

Subsequently, the exhaust valve 5 is opened and the order process according to FIG. 1 starts. Here, the displacer 6 further undergoes a constant downward movement to reduce the volume of the metering chamber 4 to maintain a uniform outlet pressure. The medium 1 is thus pushed out of the metering chamber 4 through the outlet valve 5 and the nozzle 9 and flows with a measured on the basis of the detected by the meter 12 properties of the medium 1 exactly to the requirements for example speed, pressure and diameter adapted volume flow to the component surface second

In the case of the control signals for the displacement drive 7 and the outlet valve 5 calculated by the control, a temporal pre-offset is set in order to compensate for control-related time delays and to provide the required volume flow of the medium 1 exactly at the required position and with the desired settings in terms of, for example, speed and cross section.

LIST OF REFERENCE NUMBERS

1

medium

2

component surface

3

metering

4

metering

5

outlet valve

6

displacement

7

displacer

8th

intake valve

9

jet

10

Arrow downwards movement

11

Arrow upward movement

12

gauge

Claims (7)

1. Method for the automated application of a viscous or liquid medium (1) to components, in particular body components of a motor vehicle, in which a dosing device (3), which comprises at least one dosing chamber (4) containing the medium (1), an outlet valve (5) and a displacer (6) connected to a displacer drive (7) for compressing and transporting the medium (1) in the dosing chamber (4), and the component are moved in relation to one another at an advancing rate in order to apply the medium (1) to the component along a predetermined path and with a defined application pattern, and a controller connected to the dosing device (3) controls the volumetric flow and the outlet pressure of the medium (1) by actuating the outlet valve (5) and the displacer drive (7), characterized in that the material properties of the medium (1) in the dosing device (3) are recorded and the measurement results are fed to the controller, which evaluates the measurement results and calculates the required volumetric-flow and outlet-pressure values while taking into account stored data records with respect to the intended path and the application pattern of the medium (1) and, in dependence on the values determined and with allowance for a time lead of the control signals, actuates the outlet valve (5) and the displacer drive (7), which is designed as an electric drive.
2. Method according to Claim 1, characterized in that the medium (1) is an adhering or sealing medium.
3. Method according to either of Claims 1 and 2, characterized in that the material properties of the medium (1) are recorded cyclically or constantly in the dosing device (3).
4. Method according to at least one of the preceding claims, characterized in that at least the viscosity, temperature, density and/or chemical composition of the medium (1) are taken into account as material properties thereof.
5. Method according to at least one of the preceding claims, characterized in that the displacer (6), which is movable in the dosing chamber (4) in relation to the latter, compresses the medium (1) when the outlet valve (5) is closed and pushes the volume of medium (1) that is required for the application to the component out of the dosing chamber (4) when the outlet valve (5) is open.
6. Method according to at least one of the preceding claims, characterized in that, to increase the volumetric flow of the medium (1), the electric displacer drive (7) and the displacer (6) at first provide a higher compressing power than is required for the calculated volumetric flow and this compressing power is subsequently reduced to the level calculated for the volumetric flow.
7. Method according to at least one of the preceding claims, characterized in that, to reduce the volumetric flow of the medium (1), the electric displacer drive (7) is interrupted for a predetermined unit of time.

Images