Abstract:
The invention relates to a method for cleaning at least one surface ( 12 ) of a component ( 10 ), using a cleaning device ( 14 ), wherein the surface ( 12 ) of the component is cleaned by a cleaning head ( 18 ) movable by a positioning device ( 16 ), said cleaning head ( 18 ) exerting a contact pressure on the component ( 10 ). The positioning device ( 16 ) has a rough positioning system ( 20 ) and a fine positioning system ( 22 ), wherein the cleaning head ( 18 ) is moved in a force controlled manner by the rine positioning system ( 22 ) in at least one direction of movement ( 24, 26, 28, 30, 32, 34 ). The invention also relates to a corresponding cleaning device for implementing the inventive method.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a method for cleaning at least one surface of a component using a cleaning device, the surface of the component being cleaned by means of a cleaning head which can be moved by a positioning device, while forming a contact pressure of the cleaning head on the component, according to the precharacterizing clause of claim  1 . Furthermore, the invention relates to a cleaning device which serves for cleaning at least one surface of a component and has a cleaning head which can be moved by means of a positioning device, corresponding to the precharacterizing clause of claim  9 .  
         [0003]     2. Related Art of the Invention  
         [0004]     Methods and cleaning devices of the type stated above are known. DE 42 21 026 A1 discloses a cleaning robot for a printing machine. EP 0 642 318 B1 discloses a device for cleaning windows which has for this purpose a robotic control device with a sensor function for object geometry sensing. These known cleaning systems are disadvantageous, since an undesirably severe collision with the component to be cleaned can only be avoided with relatively great expenditure. In this respect, it is possible in principle to determine precisely the complete geometry of the respective component and transfer it in the form of data to an associated control unit. Furthermore, damage to the component by the cleaning device during the cleaning operation can be virtually ruled out by suitable sensor means, but with correspondingly great expenditure in terms of apparatus and control technology.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the invention to propose a method and a suitable cleaning device of the type stated at the beginning which allow automated cleaning of a component which can be controlled relatively easily and can be implemented correctly.  
         [0006]     To achieve the object, a method with the features of claim  1  is proposed. The method according to the invention is distinguished by the fact that the positioning device has a rough positioning system and a fine positioning system, the cleaning head being moved in a force-controlled manner by means of the fine positioning system in at least one direction of movement.  
         [0007]     On the basis of the force-controlled movement of the cleaning head, it is possible to limit the contact pressure by means of the fine positioning system with regard to its maximum value and thereby to predetermine it in a defined form. As a result, on the one hand the occurrence of unexpectedly great pressing or colliding forces between the cleaning head and the component is avoided and on the other hand it is made possible for correct cleaning of the component to be implemented even without sensors and/or without sensing of the complete geometry of the component, that is to say merely with knowledge of the general or approximate contour of the component, since the cleaning device is adapted to the component tolerance that is to be expected. Consequently, even inaccuracies with regard to a positioning of the respective component do not have to be sensed, in particular before the beginning of a cleaning operation, since they are compensated up to predeterminable tolerances on the basis of an adaptive behavior of the fine positioning system similar to a spring element as a result of the force-controlled movement. Consequently, the cleaning head can be moved along at least one axis of movement by means of the fine positioning system within a predeterminable and consequently limited tolerance window. In this way, the movement of the cleaning head in contiguous contact with the component can take place by means of the fine positioning system alone, utilizing the advantages stated above, or by means of simultaneous actuation of the rough positioning system and the fine positioning system.  
         [0008]     The contact pressure is advantageously variable, and in particular can be set infinitely variably, to optimize cleaning. As a result, the contact pressure can be predetermined in dependence on an active contact surface of the cleaning head of varying size and/or in dependence on a parameter of the component. In this way it is possible to produce a component-adapted and cleaning-optimizing contact pressure value by means of the cleaning device, it also being possible, if appropriate, for contact pressure values of different magnitudes to be chosen during a cleaning operation, in dependence on the respective direction of movement.  
         [0009]     The changing of the contact pressure on the fine positioning system may take place in an automated or manual manner before and/or during the cleaning operation. Automated changing of the contact pressure is possible for example by means of a preprogrammed control device. The cleaning device is consequently characterized by particularly high flexibility with respect to the main parameter “cleaning force”, while operationally reliable cleaning of the component is at the same time ensured along with relatively low control expenditure. In this case, the cleaning head can be moved manually by means of a manipulator as the positioning device or else in an automated manner by means of a robot as the positioning device. A manipulator (teleoperator controlled by an operator) allows particularly easy-to-handle and—in comparison with a wiping movement carried out directly, that is to say purely manually—ergonomically favorable cleaning of the component.  
         [0010]     Also proposed for achieving the object is a cleaning device with the features of claim  9 . The cleaning device according to the invention is distinguished by the fact that the positioning device has a rough positioning system and a fine positioning system, the movement of the cleaning head being force-controlled by means of the fine positioning system at least in one direction of movement. By means of a cleaning device of this type, the advantages previously mentioned with respect to the method can be achieved. Furthermore, a force-controlling fine positioning system can be realized in a relatively simple form of construction. This applies in particular if the fine positioning system is formed as a functional unit with limited maximum force. For this purpose, the fine positioning system may have for at least one, and preferably all, of the directions of movement of the cleaning head that are relevant to component collision a respectively assigned fine positioning element for predetermining the contact pressure specific to the direction of movement. The fine positioning element preferably includes a telescopic adjusting mechanism, so that the cleaning head can be displaced by means of the fine positioning system along at least one axis of movement within a predetermined tolerance window. In this case, the tolerance window is defined by the maximum adjusting displacement of the fine positioning system and/or by the geometry of the cleaning head. The fine positioning element can be set in particular infinitely variably with regard to its maximum adjusting force, while forming the contact pressure, for example by means of a pneumatic or hydraulic actuating unit. Actuating units of this type allow relatively simple and rapid setting in terms of control technology of one or, if appropriate, more than one different contact pressure.  
         [0011]     The cleaning head is advantageously adjustable in its position by means of the fine positioning system along three axes of movement which are substantially orthogonal to one another. In addition, the cleaning head can preferably be moved rotatably about at least one axis of rotation. In this case, the rotational movement may take place for example by means of the rough positioning system, in particular in the form of a robot arm. Such a complexly movable cleaning head allows automated and sufficiently accurately reproducible cleaning even of geometrically differently shaped components, if appropriate with suitable wiping movements. If there are possibilities of collision with the component on account of a rotational wiping movement of the cleaning head, this movement may also be produced by means of a correspondingly force-controlling fine positioning element, so that even in a rotational wiping movement a maximum upper limit of the contact pressure or the collision force cannot be exceeded. The cleaning head may consequently have for at least one, and preferably all, of the directions of movement that are relevant to component contact a corresponding cleaning stop surface, which is assigned a respective fine positioning element.  
         [0012]     According to a preferred embodiment, the cleaning head is exchangeably fastened to the fine positioning system, for example by means of a bayonet fastening system. As a result, a rapid cleaning head change, in particular in the case of a soiled cleaning head, and more flexible component cleaning—with respect to the use of differently formed cleaning heads—are made possible.  
         [0013]     The cleaning device may be formed as a manipulator device or, for automated cleaning, as a robot device. In the case of a robot device, the rough positioning device is preferably provided with a movable robot arm, fastened to the free end of which is the fine positioning system, which carries the cleaning head. For at least partially automated positioning of the cleaning head and cleaning of the component, the cleaning device is preferably provided with a programmable open-loop and/or closed-loop control device.  
         [0014]     The cleaning head advantageously has a three-dimensionally extending cleaning surface. In this respect, it may include at least one stop shoulder, which can be moved with its cleaning stop surface frontally against a component edge, while forming the contact pressure. The cleaning surface is formed particularly advantageously in a substantially U-shaped or L-shaped manner. Furthermore, the cleaning surface may have at least one undercut, which can be brought into contiguous contact with a component surface. This allows component surfaces lying on the front side and component surfaces lying on the rear side, such as for example a bent-around region of a vehicle door, to be cleaned by means of the cleaning head in an operationally reliable and rapid manner in a single wiping operation.  
         [0015]     The cleaning head is preferably provided on its component contact side with at least one exchangeable cleaning element, it being possible for the cleaning element to be a sponge and/or a brush element and/or a cloth, and in particular a microfiber cloth. The determination of a suitable cleaning element may be based on the respective cleaning task to be performed, so that the cleaning device can be used flexibly for solving a wide variety of cleaning problems. Attaching the cleaning element to the cleaning head can in this case take place in an automated or manual manner.  
         [0016]     The cleaning device advantageously has a store for the intermediate storage of at least one cleaning head and/or at least one cleaning element. Furthermore, it may have a cleaning-head and/or cleaning-element handling device. A handling device of this type may serve for example for cleaning the cleaning head and/or the cleaning element and, if appropriate, for additionally wetting it with a cleaning fluid prior to carrying out wet cleaning of a component.  
         [0017]     The component to be cleaned may be, for example, a component of a vehicle body with at least one surface to be cleaned in a defined manner with regard to the contact pressure to be applied. For example, in outer regions of the frame, that is in regions of so-called “A, B or C pillars”, vehicle doors to be provided with coating films and previously coated vehicle doors can be cleaned by means of the cleaning device in an operationally favorable manner prior to the coating film application. Furthermore, seal seating surfaces of components of a body can be effectively cleaned by means of the cleaning device before applying a corresponding sealing tape, or else adhesive surfaces can be cleaned in preparation, the flexible way in which the cleaning device, and in particular the cleaning head, can be configured meaning that there are virtually no restrictions with respect to the component geometry that can be cleaned. A cleaning device formed as a robot can be advantageously combined with further processing or assembly devices of a production plant or, after attaching a suitable processing head, can also be used for carrying out some other processing step other than cleaning.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     Further advantages of the invention emerge from the description.  
         [0019]     The invention is explained in more detail on the basis of a preferred exemplary embodiment with reference to a schematic drawing, in which:  
         [0020]      FIG. 1  shows a schematic perspective representation of a cleaning device according to the invention and of a component to be cleaned;  
         [0021]      FIG. 2  shows a schematic perspective representation of a detail of the cleaning device of  FIG. 1  on an enlarged scale;  
         [0022]      FIG. 3  shows a schematic perspective representation of a cleaning head, partially provided with a cleaning element, of the cleaning device of  FIG. 1  on an enlarged scale;  
         [0023]      FIG. 4  shows a schematic perspective representation of the cleaning head, provided with the cleaning element, of  FIG. 3  in abutting contact with the component and  
         [0024]      FIG. 5  shows a further perspective representation of the cleaning head provided with the cleaning element in abutting contact with the component. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]      FIGS. 1 and 2  show a cleaning device  14  for cleaning a surface  12  of a component  10  in a schematic representation. In the present exemplary embodiment, the component  10  is a component of a vehicle body in the form of a vehicle door, the surfaces  12  of which that are to be cleaned being formed by the window frame. In particular, the outer surface on the front side of the so-called “A and B pillars” or “B and C pillars” of a vehicle door as well as the adjoining bent-around regions lying on the rear side of the vehicle door are to be cleaned or freed from dust by means of the cleaning device  14 . The operation of cleaning these regions of a vehicle door may for example represent component preparation for subsequent coating film application. For cleaning the component, the cleaning device  14  has a cleaning head  18  which can be moved by means of a positioning device  16  and can be brought into cleaning contact with the component  10 , or with its surfaces  12  to be cleaned, while forming a contact pressure which generally influences the cleaning action.  
         [0026]     The positioning device  16 , which is part of a robot  36  or an industrial robot, includes a rough positioning system  20  and a fine positioning system  22 . The rough positioning system  20  is formed as a robot arm  46  which can be moved in an automated manner, has six axes which can be moved in an automated manner and fastened to the free end of which is the fine positioning system  22 , which carries the cleaning head  18 . The cleaning head  18  is exchangeably fastened to the fine positioning system  22 , for example by means of a bayonet fastening system (not represented in the figures). The rough positioning system  20  serves for the rough spatial positioning of the cleaning head  18  with respect to the component  10 , the cleaning head  18  generally not yet being brought into contiguous contact with the component  10 . To establish desired contiguous contact for the cleaning operation, a movement of the cleaning head  18  following the rough positioning of the robot arm  46  can then take place by means of the fine positioning system  22  in relation to the robot arm  46 . This movement in the course of fine positioning of the cleaning head  18  takes place in a force-controlled manner in at least one possible direction of movement  24 ,  26 ,  28 ,  30 ,  32 ,  34 . In the case of the present exemplary embodiment, movements of the cleaning head  18  along the axes of movement in the “±” direction according to the double-headed arrows  24 ,  26 ,  28  are force-controlled by means of the fine positioning system  22 , while the movements about the axes of rotation according to the double-headed arrows  30 ,  32 ,  34  are exclusively displacement-controlled by means of the rough positioning system (robot arm  46 ). The three axes of movement  24 ,  26 ,  28  are substantially orthogonal to one another and are perspectively represented in  FIG. 1  with respect to the shown operating position of the robot arm  46 . The fine positioning system  22  is formed as a functional unit with limited maximum force, it having for this purpose, for the directions of movement  24 ,  26 ,  28  of the cleaning head  18  that are relevant to component collision, a respectively assigned fine positioning element  38 ,  40 ,  42 , so that the contact pressure respectively occurring between the cleaning head  18  and the component surface  12  during the cleaning operation is limited specifically with respect to the direction of movement.  
         [0027]     The fine positioning elements  38 ,  40 ,  42  in each case include a telescopic adjusting mechanism with a respectively predetermined adjusting displacement. The cleaning head  18  is displaceable by means of the fine positioning system  22  along the axes of movement  24 ,  26 ,  28  within a defined tolerance window. The tolerance window is in this case predetermined by an adjusting displacement of the fine positioning system  22  respectively adapted to the cleaning task and is limited with regard to its maximum extent. If appropriate, the geometry of the cleaning head  18  may also represent an additional restriction on the adjusting displacement of the cleaning head  18 , that is to say for the case in which the cleaning head  18  collides into the component  10  with a stop surface, described in more detail further below, while forming the contact pressure, before the associated telescopic adjusting mechanism has been extended to a maximum possible length of adjusting displacement. The fine positioning elements  38 ,  40 ,  42  can be variably set with regard to their maximum adjusting force, while forming a respectively desired contact pressure. In this respect, the fine positioning elements  38 ,  40 ,  42  have a pneumatic or hydraulic actuating unit.  
         [0028]     The fine positioning elements  38 ,  40 ,  42 , in each case having a telescopic adjusting mechanism, are respectively formed as a cylinder-piston system, a piston movement preferably taking place according to the present exemplary embodiment by means of compressed air. The open-loop or closed-loop control of the air pressure may in this case take place infinitely variably by means of an associated proportional valve with respect to the respective direction of movement. The cleaning device  14  corresponding to  FIG. 1  includes five proportional valves  64 , which can be actuated by means of an open-loop or closed-loop control system  66  and make possible a force-controlled movement of the cleaning head  18  in the “±” directions  26 ,  27  and in the “+” direction  24 . To perform the cleaning task represented in FIGS.  1  to  5 , a force-controlled movement in the “−” direction  24  is not required (see in particular  FIG. 2 ), but can likewise be realized in a corresponding way.  
         [0029]     The cleaning head  18  has for at least one direction of movement that is relevant to component contact, in the present exemplary embodiment for the direction of movement  28 , two cleaning stop surfaces  44  which are spaced apart from and opposite each other, the fine positioning element  42  being functionally assigned to these cleaning stop surfaces  44 . Furthermore, the cleaning device  14  is provided with a programmable open-loop and or closed-loop control device for the at least partially automated positioning of the cleaning head  18  and for the corresponding implementation of the actual cleaning operation on the component  10 .  
         [0030]     The cleaning head  18  includes a carrier structure  60 , fastened to which is a foam element  62 , which carries an exchangeable cleaning element  56  in the form of a microfiber cloth. In the present exemplary embodiment according to FIGS.  3  to  5 , the cleaning head  18  is provided with a three-dimensionally extending cleaning surface  48 . In this case, it has two stop shoulders  50 , which are spaced apart from and opposite each other and can be moved with their respective cleaning stop surface  44  frontally against a corresponding component edge  52 , while forming the contact pressure. For this purpose, the cleaning surface  48  is formed in a substantially U-shaped manner and includes for each stop shoulder  50  an undercut  54 , which can be brought into contiguous contact with a component surface  12 . Depending on the cleaning task, the cleaning head  18  may be provided, if appropriate, with an additional suction and/or blowing system (not represented in the figures), for example with compressed air as the operating medium.  
         [0031]     The cleaning device  14  may have a store (not represented in the figures), formed as a changing magazine, for the intermediate storage of at least one cleaning head  18  and/or a cleaning element  56 . Furthermore, a cleaning-head and or cleaning-element handling device may be provided, so that both the cleaning head preparation and the cleaning operation itself can be implemented in an automated manner.  
         [0032]     The movement of the cleaning head  18  in contiguous contact with the component  10  may take place by means of the fine positioning system  22  on its own or, if need be, also by means of simultaneous actuation of the rough positioning system  20  and the fine positioning system  22 . To optimize cleaning, the contact pressure can be variably set. In this case, the contact pressure can be predetermined in dependence on an active contact surface of the cleaning head  18  of varying size and/or in dependence on a parameter of the component. “Contact surface” is understood here as meaning that part of the cleaning surface of the cleaning head  18  which is in contiguous contact with the component  10  to be cleaned, while forming the contact pressure. One possible parameter of the component which should be taken into account for determining a desired maximum contact pressure value is the inherent stability or the compliance of the component  10 , in particular in the region of the surface  12  that is respectively to be cleaned, since the cleaning result can also be influenced by this. Consequently, it may be entirely appropriate for contact pressure values of different magnitudes to be predetermined during a cleaning operation, including on the basis of possibly differing degrees of soiling of the component surfaces  12 , it being possible for the changing of the contact pressure on the fine positioning system  22  to take place in an automated or manual manner before and/or during the cleaning operation.  
         [0033]     The operating mode of the cleaning device  14  may, for example, be such that the robot arm  46  carrying the fine positioning system  22  at its free end is loaded with a suitable cleaning head  18  in an automated manner in a cleaning head changing station. The robot arm  46 , acting as a rough positioning system  20 , then moves the cleaning head  18  into a starting position, from which the cleaning head  18  can be moved in a force-controlled manner by means of the fine positioning element  38  in the direction of movement  24  and can consequently be brought into contiguous contact with the component  10 , while forming the contact pressure, the desired contact pressure value having been entered in advance in the open-loop or closed-loop control system  66 . In this case, the fine positioning element  38  is preferably not extended by the maximum possible length of adjusting displacement, so that, if appropriate, automatic readjustment of the cleaning head  18  in the direction of movement  24  by the remaining residual length of adjusting displacement is possible, while ensuring permanent contiguous contact with the component  10 . The fine positioning element  38  consequently has the effect of a spring element, but without a spring characteristic, since a virtually constant contact pressure is always produced, independently of the adjusting displacement. Once the contiguous contact has been established between the cleaning head  18  and the component  10 , the cleaning head  18  is moved in a force-controlled manner by means of the fine positioning element  42  in the way shown in  FIG. 4  until it butts with a cleaning stop surface  44  of the corresponding stop shoulder  50  against a component edge  52  to be cleaned (bent-around region of the B pillar), while forming the contact pressure predetermined for the fine positioning element  42 . The cleaning head  18  is subsequently moved along the B pillar by means of the fine positioning element  42  and/or by means of the robot arm  46  (see in particular  FIG. 5 ), both the front-side contact surface  12  and the component edge  52  (bent-around region) being cleaned simultaneously. If appropriate, additional handling steps may also be provided for the cleaning head  18  during the cleaning operation. What is decisive for this cleaning operation is that all the contact pressures occurring are produced by means of the respectively associated fine positioning element and are consequently predetermined in terms of their magnitude.  
         [0034]     In the present exemplary embodiment, the cleaning head  18  can be moved by means of the fine positioning system  22  within a tolerance window of about ±25 mm for each direction of movement  24 ,  26 ,  28 . Even if the cleaning head is moved along a predetermined path, adapted to the component contour, by means of the rough positioning system  20 , it is possible on account of the fine positioning system  22  to dispense with relatively complex sensor equipment for the suitable positioning of the cleaning head  18  on the component  10  while forming a contact pressure.  
         [0035]     The further structural design and operating mode of the cleaning device are known per se, so there is no need for a more detailed description.