Abstract:
The invention relates to a method for process automation, for connecting the edge of two correspondingly profiled ends of at least one profiled sealing element, said profiled sealing element being already applied to a surface of a vehicle or a vehicle component. The invention also relates to a device for carrying out said method.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. national stage of International Application No. PCT/EP2006/007675, filed on 3 Aug. 2006. Priority is claimed on German Application No. 10 2005 039 214.8, filed on 17 Aug. 2005. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to a method for connecting the similarly profiled ends of at least one sealing strip at the butt joint present between them after the strip has been attached to the surface of a vehicle or vehicle component. The invention also pertains to a device for implementing the method. 
     2. Description of the Related Art 
     Profiled sealing strips on vehicles or vehicle components serve to seal off a movable vehicle component such as a door against the body frame when the door is closed. These types of profiled sealing strips are usually attached to the vehicle door by means of auxiliary devices comprising several segments. 
     To shorten production times and to lower investment costs, DE 101 38 781 A1 proposes a method for attaching a seal to a vehicle door, in which the seal, which is in the form of an endless profiled strip on a roll, is pulled off the roll, and the adhesive surface on the strip is rolled onto the door all the way around along the line indicating where the strip is to be attached. The words “rolled onto” are used to express the idea that, to attach the strip to the door, pressure rolls are used to press the seal along successive portions of its length onto the surface of the vehicle door, following along the predefined mounting line. The advantage of this rolling method is that it allows an all-around seal to be installed in its entirety in a single continuous step. The attachment occurs in this case by means of a robot, which has guide means for the sealing strip. After the attachment process is over, the strip is cut by a cutting device on the robot to form abutting ends. The ends of the profiled sealing strip resting against each other at this butt joint can shift position with respect to each other. As a result, not only the overall visual impression of the seal is disturbed, but also it becomes easier for damage to occur to the seal in the area of the butt joint. Certain types of vehicles, furthermore, such as all-terrain vehicles require a closed-door seal all the way around the door to provide a water-tight barrier. 
     It would therefore be desirable to have a way of connecting the two abutting ends of the profiled sealing strip without losing the mounting and cost advantages offered by the previously described rolling method for attaching the sealing strip. 
     SUMMARY OF THE INVENTION 
     The invention is therefore based on the task of creating a method, suitable for process automation, for connecting the two similarly profiled abutting ends of at least one profiled sealing strip, which has previously been attached to the surface of the vehicle or vehicle component. In addition, an advantageous device for implementing the method is also to be provided. 
     This task is accomplished by a method with the features of Claim  1 . 
     The method is suitable for connecting the two similarly profiled abutting ends of a single profiled stealing strip for the production of, for example, a door or sliding roof seal. The method can also be used, however, to connect two similarly profiled abutting ends of two profiled sealing strips which have previously been attached to the vehicle or vehicle component. The only requirement is that the two abutting ends be similarly profiled. 
     The ends of the profiled sealing strip attached to the surface of a vehicle or vehicle component initially lie flush against each other at the butt joint present between them. So that the two ends can be connected permanently together in this joint area, it is first necessary to produce a temporary working gap between the two ends. This is done by moving the ends of the minimum of one profiled sealing strip away from each other. In particular, grippers can be used to grip each of these ends a certain distance away from the joint and to pull the ends apart. The distance that each gripper moves is only a few millimeters. As a result, a gap is formed between the ends of the profiled sealing strip, which gap tapers down in a wedge-like manner toward the surface of the sealing strip by which the strip is attached to the surface of the vehicle or vehicle component. Alternatively, the working gap can be produced by using a hold-down device to compress the strip a certain distance away from the butt joint. The deformation of the profiled sealing strip has the effect of forming a working gap at the butt joint. 
     A welding film is introduced into this working gap. By the input of thermal energy, this film is welded to the ends of the minimum of one profiled sealing strip after the working gap at the butt joint has been closed again. The working gap is closed either by releasing the grip of the grippers on the profiled ends or by actively moving the grippers toward each other. In addition, pressure can be exerted on the ends of the profiled sealing strip in such a way as to assist the welding at the butt joint. The welding film introduced into the working gap consists, for example, of a thermoplastic elastomer, which bonds to the sealing material under the action of heat. Depending on the materials which are to be welded (welding film/profiled sealing strip), a temperature of approximately 100-300° C. will be required for this purpose. 
     The required thermal energy can be supplied to the profiled ends or to the welding film or to both the profiled ends and the welding film by conduction, radiation, or convection. In particular, the thermal energy can be supplied by conduction by bringing the profiled ends in the working gap to be heated into temporary contact with a hotter body such as a heating plate. To guarantee the temperature required for welding, it is necessary, when introducing the thermal energy, to take into consideration the subsequent heat loss, which is determined by the chronological sequence of the individual steps, by the selected materials, and by the ambient conditions. 
     To prevent migration of the profiled ends at the butt joint when the welding operation is being actively assisted by the grippers, in an advantageous embodiment of the invention a shaped gripper conforming to the shape of the profile is also used. The only function of the shaped gripper is to stabilize and to guide the profiled sealing strip in the immediate area of the butt joint. It exerts no force acting in the axial direction of the profiled sealing strip. 
     An advantageous device for implementing the method comprises means for producing the working gap at the ends of the profiled sealing strip, a welding film feeder, a heating system for welding the welding film to the ends of the profiled sealing strip, and a positioning unit acting in at least two planes to move the welding film feeder and the heating system between a rest position and a working position. 
     So that the inventive device can be integrated into a production line for an automobile, it is preferably mounted on the arm of a robot, which moves the device into a defined position with respect to the butt joint between the profiled ends to be connected to each other. By way of kinematic reversal, it is also possible for the device used to implement the method to be stationary, e.g., it can be mounted on a support frame, and for the body part, to which the seal has already been applied, to be moved in such a way as to orient it with respect to the device. 
     The means for producing the working gap preferably comprises two grippers, each with two arms which can move toward and away from each other, and at least one drive for changing the distance between the two grippers in the axial direction of the length of the profiled strip in the area of the butt joint. The two arms of each gripper are preferably mounted so that they can pivot with respect to each other and are designed in the form of plates in the area of the gripping jaws to avoid damage to the sensitive profiled sealing strip. Each gripper is equipped with its own pivoting drive to pivot it. 
     Alternatively, the means for producing the working gap can have two hold-down devices, which can be moved by a drive between a starting position and a working position. In the working position, the hold-downs press down on the profiled sealing strip on both sides of the butt joint. In the rest position, the hold-down devices are located above the profiled sealing strip. The hold-down devices can be moved into and out of the working position by a driven linear slide or pivot arm. 
     The heating system of the device preferably has a heating plate, which is heated in particular by an electrical resistance heating system. The plate itself can be made of ceramic, for example. The thickness of the plate is coordinated with the width of the working gap, so that the surfaces of the plate come in contact with the ends of the profiled strip. 
     The welding film feeder has two clamping jaws which can be moved toward each other to hold the welding film taut; the two clamping jaws have aligning notches, the size of which is equal at least to the cross section of the profiled sealing strip surrounded by the clamping jaws. When the clamping jaws are moved toward each other, the welding film present between the clamping jaws is stretched out taut. The welding film can be fed as individual pieces or as a continuous length to the clamping jaws for the welding process. If the welding film is fed in pieces, the pieces are first made by stamping, for example, and then inserted between the clamping jaws by a manipulator. In a preferred embodiment of the invention, however, the welding film feeder has a supply spool and a wind-up spool for a web-like welding film and guide means between the spools, by means of which the web-like welding film which has been pulled off the supply spool is conducted between the clamping jaws in the area of the aligning notches. During the welding process itself, the welding film is clamped between the clamping jaws. Then the clamping jaws are released, and a fresh section of welding film is pulled from the supply spool and fed to the next process. As a result of the welding of the film web to the ends of the profiled stealing strip in the area of the butt joint, a piece of film corresponding to the cross section of the profiled strip is removed from the film web. For this reason, the width of the film web must be greater than the maximum height of the cross section of the butt joint, because the film web would otherwise be separated by the welding process and therefore could not be wound up and driven by the wind-up spool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram, in perspective, of a device for implementing the inventive method; and 
         FIGS. 2   a - d  show schematic diagrams of the various steps of the inventive method. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device for implementing the method, designated overall by the number  1 , consists essentially of two profiled grippers  2   a ,  2   b , a welding film feeder  3 , and a heating system  4 . The welding film feeder  3  and the heating system  4  are attached by vertical slides  5 ,  6  to a common horizontal slide  7 . In the exemplary embodiment shown here, the device  1  is supported via the horizontal slide  7  on a stationary stand (not shown for the sake of clarity). 
     The profiled grippers  2   a ,  2   b  each have two opposing, pivotable arms  8   a ,  8   b , which can be pivoted in the direction of the arrows  11   a ,  11   b  by means of a pivoting drive mounted in the housing  9   a ,  9   b . The distance between profiled grippers  2   a ,  2   b  can also be changed by means of at least one drive (not shown in  FIG. 1 ), which moves the grippers in the direction of the arrows  35 . 
     In  FIG. 1 , the arms  8   a ,  8   b  are resting on the ends  12 ,  13  of a profiled sealing strip  14 , which has previously been attached to the surface of the vehicle door. For this purpose, an adhesive surface, which is glued down along the lines  16   a ,  16   b  intended for the attachment, is provided on the bottom surface of the base  15  of the profile of the hollow-chambered sealing strip. 
     At one end, the heating system  4  has a heating plate  17  of ceramic material, which tapers down to a knife edge. The heating plate  17  is mounted in a holder  18  with an electric resistance heater for tempering the heating plate  17 . The holder  18  is mounted on the vertical slide  5 , which, in  FIG. 1 , is in its upper end position above the butt joint  33  between the ends  12 ,  13  of the profiled sealing strip  14 . From this position, the heating plate  17  can be moved by the vertical slide  5  into its working position, as will be explained below on the basis of  FIG. 2 . 
     The welding film feeder designated overall by the number  3  has a first stationary clamping jaw  19  and a movable clamping jaw  21 , which can be moved toward and away from the stationary jaw  19 . At their bottom ends, the two clamping jaws  19 ,  21  have aligning notches  22 ,  23 , which are slightly larger than the cross section of the profiled sealing strip  14 . The profiled sealing strip can therefore be held in the notches  22 ,  23  of the clamping jaws  19 ,  21 . The movable clamping jaw  21  is mounted on a horizontal slide  24 , by means of which the clamping jaws can be pressed against each other and moved away from each other again. This horizontal slide  24  for holding the movable clamping jaw  21  is itself mounted by way of a bracket  25  on the vertical slide  6 . The vertical slide  6  is located in an upper end position above the profiled sealing strip, and the horizontal slide  7  is in a rear terminal position, which defines the rest position of the welding film feeder  3 . A spool stand  32  for a supply spool  26  and a wind-up spool  27  for a web-like welding film  28  are also mounted on the vertical slide  6 . The welding film  28  pulled from the supply spool  26  is conducted by guide means (not shown) between the clamping jaws  19 ,  21  at the level of the notches  22 ,  23  and pulled around the edge  29  of the stationary clamping jaw  19 , i.e., the edge in the forward position in the figure. The height  31  of the film web is slightly greater than the maximum height of the notches  22 ,  23  to guarantee that the used-up film remaining after the welding of the film web can be transported reliably to the wind-up spool  27 . 
     The method according to the invention is explained in greater detail below: 
     First, the vehicle door with the profiled sealing strip  14  already attached to it is brought into the processing position shown in  FIG. 1 . Then a working gap  34  must be produced so that the butt joint  33  between the two similarly profiled ends  12 ,  13  of the sealing strip  14  can be connected. For this purpose, the abutting ends  12 ,  13 , as shown in  FIG. 2   a , are moved away from each other by the use of gripper arms  8   a ,  8   b , which grip the ends of the strip a certain distance away from the butt joint  33 , pull them apart in the direction of the arrows  35 , and hold them in this position. As a result, the working gap  34 , which tapers down in a wedge-like manner toward the base of the profiled strip  15 , is formed. 
     Then the heating plate  17  of the heating system  4 , with the wedge-shaped tip in front, is lowered into the working gap  34 . For this purpose, the vertical slide  5  is moved downward out of the end position above the butt joint  33  as shown in  FIG. 1 . The ends of the strip thus come into contact with the surfaces of the heating plate  17 . The conduction of the heat can be promoted by using the grippers  2   a ,  2   b  to move the ends  12 ,  13  of the strip toward each other as shown by the arrows  35  in  FIG. 2   b  after the heating system  4  has been lowered. After the predetermined length of time required to allow the necessary heat input has passed, the heating system  4  is removed from the working gap  34  by the vertical slide  5 . If the ends  12 ,  13  of the profiled sealing strip  34  have been squeezed together, as shown in  FIG. 2   b , the grippers  2   a ,  2   b  must first be moved away from each other again, as shown in  FIG. 2   c , to obtain the working gap  34 . 
     To introduce the welding film  28  into the working gap, a piece of fresh welding film is pulled from the supply spool  26  while the clamping jaws  19 ,  21  are open and brought into the area of the notch  23  in the movable clamping jaw  21 . Then the movable clamping jaw  21  is pushed against the stationary clamping jaw  19  in the direction of the arrow  36  by the horizontal slide  24 . As a result, the welding film  28  is held taut between the two clamping jaws. The taut piece of welding film  28  is now introduced into the working gap by the use of the vertical and horizontal slides  6 ,  7  to move the welding film feeder  3  into position. The clamping jaws  19 ,  21  thus surround the profiled sealing strip  14 , as shown in  FIG. 2   d . Then the working gap  34  at the butt joint  33  is released, so that the ends  12 ,  13  of the profiled sealing strip  14  arrive in contact with the welding film  28 . The contact between the welding film  28  and the ends  12 ,  13  is assisted by using the grippers  2   a ,  2   b  to press the ends in the direction of the arrows  35  shown in  FIG. 2   d.    
     The thermal energy just introduced into the ends of the profiled sealing strip  14  ( FIG. 2   b ) has the effect of welding the tautly held section of film  28  to the ends  12 ,  13  and thus of connecting them together at the butt joint  33 . After the welding is complete, the welding film feeder  3  is moved up and away from the profiled sealing strip  14 , so that the device  1  can be prepared to connect the abutting ends of the next sealing strip. The web-like welding film  28  has been severed along the contour of the profiled sealing strip  14 , so that the film web now has a notch corresponding to the cross section of the profiled sealing strip  14  at this point. After the clamping jaws have been released, the used-up part of the film web with this notch is pulled by the wind-up spool  27  around the edge  29  of the stationary clamping jaw  19  until the notch is aligned with the notch  22  in the stationary jaw. As a result, it is guaranteed that only one layer of the web-like film web is welded to the ends of the profiled sealing strip. An alternative solution consists in winding up the used-up film web by way of separate deflecting rolls on a wind-up, spool located on the opposite side of the clamping jaws  19 ,  21  from the supply spool. 
     The pressing-together of the ends  12 ,  13  of the profiled sealing strip  14  illustrated in  FIGS. 2   b  and  2   d  serves merely to support the inventive method; it is not mandatory. In particular, it is sufficient for the welding of the ends of the sealing strip with the welding film (see  FIG. 1   d ) simply to pivot the gripper arms  8   a ,  8   b  away from each other to release the ends  12 ,  13 . The natural tension of the elastic sealing strip is sufficient to bring the ends of the sealing strip securely against the welding film.