Abstract:
A sealing nozzle having a flattened tubular part for discharging a sealer is disclosed. A restrictive means is provided so as to stretch out from one side to the other inside a sealer passage of the flattened tubular part and to restrict the flow of the sealer.

Description:
FILED OF THE INVENTION 
       [0001]    The present invention relates to a sealing nozzle and a method for producing a vehicle body by use of the nozzle. 
       BACKGROUND OF THE INVENTION 
       [0002]    Shown in  FIG. 12  hereof is an ordinary vehicle door  100  which has an outer plate  101  on the vehicle outside and an inner plate  102  disposed alongside the outer plate  101 . 
         [0003]      FIG. 13  is a cross-sectional view taken along line  13 - 13  of  FIG. 12 . In  FIG. 13 , the outer plate  101  and the inner plate  102  are integrally joined by bending the rim part of the outer plate  101  back over the rim part of the inner plate  102 . Such a process is known as “hemming.” 
         [0004]    In such hemming, minute crevices will inevitably exist, raising concern over rainwater infiltration and the entry of wind. As a countermeasure to these dangers, a sealer  103  is applied as illustrated. The sealer  103  is a filling material that prevents crevices from forming, is a viscous material at the time of filling (application), and solidifies and becomes a solid material when a set amount of time passes after application. Therefore, the sealer can block out rainwater and wind. The sealer  103  is applied with a sealing nozzle. 
         [0005]    The aforementioned sealing nozzle is disclosed in Japanese Utility Model Application Laid-Open Publication No. 6-77842. This sealing nozzle is described below based on  FIG. 14 . 
         [0006]    The conventional sealing nozzle  110  shown in  FIG. 14  is comprised of a pipe  111  for transporting the sealant, a bent part  112  disposed in the middle portion of the pipe  11   1 , and a flattened tube part  114  disposed at the distal end of the pipe  111  and used to discharge the sealer from an oblong opening  113  in the distal end. 
         [0007]    Because the oblong opening  113  of the flattened tube part  114  can discharge the sealer in the form of a film, the sealer can be applied in a spread configuration. 
         [0008]    Next, a specific example of applying a sealer to a vehicle door by a sealing nozzle having a structure similar to that of the sealing nozzle  110  is described with reference to  FIGS. 15A and 15B . 
         [0009]    The sealing nozzle  120  shown in  FIG. 15A , apart from the bent part  112  ( FIG. 14 ), has substantially the same structure as the sealing nozzle  110 , and is further provided with a guide member  121  that stretches out from the pipe  111  and is used to guide the flattened tube part  114  by following the door  100  as a coating workpiece. 
         [0010]    In  FIG. 15A , the distal end of the sealing nozzle  120  is brought against the application part (boundary  124  between a folded part  122  of an outer plate and an inner plate  123 ). 
         [0011]    In  FIG. 15B , the sealing nozzle  120  is moved slowly while the sealer  125  is discharged from the sealing nozzle  120 . In this case, the boundary  124  is coated with the sealer  125 . The shape of the sealer  125  is shown in detail in  FIG. 16 . 
         [0012]    As shown in  FIG. 16 , an application start area A and a subsequent application continuation area B have different shapes. The application width Wb of the application continuation area B corresponds to the width of the distal end of the sealing nozzle  120  ( FIG. 15B ). In contrast, the application width Wa of the application start area A is markedly greater than Wb and creates an overcoating that protrudes outward to the left of the folded part  122  of the outer plate in the left-hand side of the drawing. This overcoated portion  126  must be wiped off with waste cloth or aftertreated in another manner. As a result, problems arise in that the operating time increases and the sealing operation becomes more complicated. 
         [0013]    The reason that the application start area A widens considerably is that the sealing nozzle  120  is stopped at the start of application. A need exists for removing the overcoated portion  126  and rendering clean-up work unnecessary. 
       SUMMARY OF THE INVENTION 
       [0014]    It is an object of the present invention to provide a sealing nozzle wherein clean-up work in the application start area is rendered unnecessary. 
         [0015]    According to a first aspect of the present invention, there is provided a sealing nozzle which comprises: a pipe for transporting a sealer; a flattened tubular part disposed at a distal end of the pipe for discharging the sealer from an oblong opening at a distal end of the flattened tubular part; a guide member that stretches out from one of the pipe and the flattened tubular part for guiding the flattened tubular part to an application part of a coating workpiece by following the coating workpiece; and restrictive means designed to make the flow of the sealer in the flattened tubular part in proximity to the guide member slower than the flow in an area distant from the guide member. 
         [0016]    In the nozzle of the present invention, the flow of the sealer in the flattened tubular part in proximity to the guide member is slowed down in comparison with the flow of the sealer in an area distant from the guide member by the restrictive means for varying the flow of the sealer, eliminating the concern that the sealer will protrude toward the guide member. When the sealer protrudes toward the guide member, the overcoated contaminated portion must be wiped off. The present invention, however, can eliminate the overcoated portion and dispense with wiping and other aftertreatments, as described above. 
         [0017]    Preferably, the restrictive means comprises a resistance member that projects out from the internal peripheral surface toward the interior of the flattened tubular part, or a depression that is sunk in so as to protrude from the exterior to the interior of the flattened tubular part. Therefore, the flow of the sealer can be locally restricted by the resistance member or the depression. The resistance member or the depression is simple to produce and can be easily provided to the interior of the flattened tubular part. 
         [0018]    In a preferred form, the shape of the resistance member or the shape of the depression is substantially rectangular. Resistance can be increased if a long side of the rectangle is oriented along the flow. In addition, the simple shape makes it easier to process and manufacture the sealing nozzle. 
         [0019]    Desirably, the restrictive means is designed such that a center line of the flattened tubular part is displaced toward the guide member and away from a center line of the pipe. Therefore, the sealer flows mostly along the center line of the pipe, and the flow is reduced in areas far from the center line of the pipe. The overcoated portion of sealer can therefore be eliminated, and wiping or other aftertreatments can be omitted. 
         [0020]    According to a second aspect of the present invention, there is provided a method for producing a body of an automobile by applying a sealer to a work area of at least two steel sheets that constitute the automobile body, the method comprising the steps of: providing a sealing nozzle having a pipe for transporting the sealer, a flattened tubular part disposed at a distal end of the pipe for discharging the sealer from an oblong opening at a distal end of the flattened tubular part, a guide member that stretches out from the pipe or the flattened tubular part for guiding the flattened tubular part to an application part of a coating workpiece by following the coating workpiece, and restrictive means designed to make the flow of the sealer in the flattened tubular part in proximity to the guide member slower than the flow in an area distant from the guide member; bringing the guide member against one edge part of one of the steel sheets; and applying the sealer to an overlapping area of the two steel sheets while sliding the sealing nozzle along the edge part. 
         [0021]    In the arrangement of the second aspect, the sealer can be prevented from protruding to the exterior of the vehicle body when application of the sealer is started. As a result, labor involved in applying the sealer in the manufacturing of a vehicle body can be reduced. In addition, overcoating causes increased water leaks and air cutting noise, as well as formation of rust and crevices. Because such overcoating can be removed in accordance with the present invention, formation of water leaks in the vehicle body can be prevented, the air cutting noise can be reduced, the formation of rust on the vehicle body can be prevented, and the infiltration of dirt into the vehicle body can be prevented as well. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
           [0023]      FIGS. 1A and 1B  are schematic views showing a sealer applied to an inner panel by using a conventional nozzle; 
           [0024]      FIGS. 2A and 2B  are schematic views showing an example in which the applied sealer is prevented from protruding beyond the inner panel; 
           [0025]      FIGS. 3A through 3C  are views showing a plurality of experimental examples of restricting the flow of a sealer; 
           [0026]      FIG. 4  is a schematic view showing, partially in section, a sealing nozzle according to a first embodiment of the present invention; 
           [0027]      FIG. 5A  is a cross-sectional view taken along line  5 A- 5 A of  FIG. 4 ; 
           [0028]      FIG. 5B  is a cross-sectional view taken along line  5 B- 5 B of  FIG. 4 ; 
           [0029]      FIG. 5C  is a view as seen from arrow  5 C of  FIG. 4 ; 
           [0030]      FIG. 6  is schematic view showing an operation of the sealing nozzle shown in  FIG. 4 ; 
           [0031]      FIGS. 7A and 7B  are views showing the manner in which the sealer flows through the sealing nozzle according to the first embodiment; 
           [0032]      FIG. 8  is a view showing a sealing nozzle according to a second embodiment of the present invention; 
           [0033]      FIG. 9  is a view showing a sealing nozzle according to a third embodiment of the present invention; 
           [0034]      FIG. 10  is a flowchart showing the sealant application step according to the present invention; 
           [0035]      FIGS. 11A and 11B  are views showing the manner in which the sealer is applied by the sealing nozzle of the present invention; 
           [0036]      FIG. 12  is a front view of a vehicle door; 
           [0037]      FIG. 13  is a cross-sectional view taken along line  13 - 13  of  FIG. 12 ; 
           [0038]      FIG. 14  is a perspective view showing a conventional sealing nozzle; 
           [0039]      FIGS. 15A and 15B  are views showing application of a sealer by a sealing nozzle different from the sealing nozzle shown in  FIG. 14 ; and 
           [0040]      FIG. 15  is a view showing the shape of the sealer applied as shown in  FIG. 14B . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0041]      FIGS. 1A through 2B  are views that explain details related to the development of the present invention. 
         [0042]    A coating shape of a sealer  125  such as the one shown in  FIG. 1B  is produced using the conventional sealing nozzle  120  shown in  FIG. 1A . An inner panel  123  stretches out to the right-hand side in the drawing, and the sealer  125  is therefore allowed to project to the right. By contrast, an overcoated portion  126  that extends outward to the left-hand side in the drawing is not permissible. In other words, the problem is solved by removing the hatched portion. 
         [0043]    Using a sealing nozzle  20  that has offset discharge characteristics, such as the one shown in  FIG. 2A , may produce a coating that does not have an overcoated portion, as shown in  FIG. 2B . Various studies have been conducted into the structure of the sealing nozzle  20  according to the present invention, as described below. 
         [0044]      FIGS. 3A through 3C  show experimental examples in which a model of a flattened tube part is manufactured by covering a grooved mold material  11  with a transparent sheet  12 . 
         [0045]    In  FIG. 3A , a disk  14  having a diameter of 0.5×W 1  was placed into a sealer passage  13  having width W 1 , and a sealer  15  was caused to flow from the left to the right in the drawing. Due to the resistance of the disk  14 , the distal end of the sealer became slightly asymmetrical at this point. 
         [0046]    In  FIG. 3B , a square plate  16  in which one side measures 0.5×W 1  was placed into the sealer passage  13  having width W 1 , and the sealer  15  was caused to flow from the left to the right in the drawing. Due to the resistance of the square plate  16 , the distal end of the sealer became asymmetrical at this point. The degree of asymmetry was more pronounced than that of  FIG. 3A . 
         [0047]    In  FIG. 3C , a rectangular plate  17  in which the short side measures 0.5×W 1  and the long side measures W 1  was placed into the sealer passage  13  having width W 1 , and the sealer  15  was caused to flow from the left to the right in the drawing. Due to the resistance of the rectangular plate  17 , the distal end of the sealer became asymmetrical at this point. The degree of asymmetry was more pronounced than that of  FIG. 3B . 
         [0048]    As a result of the above experiments, it was possible to confirm that a sealing nozzle having asymmetrical discharge characteristics could be obtained by placing the disk  14 , the square plate  16 , or the rectangular plate  17  as a resistance member in the sealer passage  13  at a position that was offset from the center. 
         [0049]    Based on the above knowledge, a sealing nozzle that could be used in actual practice was produced on a trial basis. 
         [0050]      FIG. 4  shows a sealing nozzle according to the present invention. 
         [0051]    The sealing nozzle  20  comprises a pipe  21  for transporting a sealer, a flattened tubular part  23  provided to the distal end of the pipe  21  and used to discharge the sealer from an oblong opening  22  in the distal end, and a guide member  24  ( FIG. 14 ) that stretches out from the pipe  21  (or the flattened tubular part  23 ) and is used to guide the flattened tubular part  23  toward an application part of the coating workpiece by following the coating workpiece. A resistance member  25  for restricting the flow of the sealant is provided to the sealer passage  13  of the flattened tubular part  23  at a position close to the guide member  24 . A rectangular plate  17  that stretches out along the flow of the sealant is shown as an example of the resistance member  25 . In addition, the resistance member  25  can be regarded as a member that projects inward from the exterior of the flattened tubular part  23 . 
         [0052]    The pipe  21  is a round tube, as shown in  FIG. 5A ;  50 % of the interior of the oblong flattened tubular part  23  is blocked by the rectangular plate  17 , as shown in  FIG. 5B ; and the rectangular plate  17  can be seen through the oblong opening  22 , as shown in  FIG. 5C . 
         [0053]    The operation of the sealing nozzle thus configured will next be described. 
         [0054]    When a sealant is applied using a sealing nozzle  20  such as the one shown in  FIG. 6 , the application start area A is larger than the application continuation area B, and an overhang  26  appears toward the interior, which is the right-hand side in the drawing. This overhang  26  is allowed. The operation of the rectangular plate  17  disposed inside the sealer passage  13  will now be described. 
         [0055]      FIGS. 7A and 7B  show flowcharts of the interior of the sealing nozzle. The flow inside the nozzle follows the Bernoulli theorem (that the sum of the static pressure and dynamic pressure is constant, assuming that the potential does not change). Static pressure can be expressed as p over density γ (p/γ), and dynamic pressure can be expressed as the square of the flow velocity v over twice the gravitational force g (v 2 /2 g). 
         [0056]    In  FIG. 7A , the flow that does not collide with the rectangular plate  17  is shown by arrow ( 1 ). Arrow ( 1 ) passes from the inlet point P 1  of the rectangular plate  17  through the point P 2  beside the rectangular plate  17  to the outlet point P 3  of the rectangular plate  17 . Because the flow passage narrows at point P 2 , velocity and dynamic pressure increase. Static pressure decreases in proportion to the increase in dynamic pressure, resulting in reduced pressure. In other words, the pressure around point P 2  is lower than that around P 1 . 
         [0057]    The flow that collides with the rectangular plate  17  is shown by arrow ( 2 ). At point P 5 , where arrow ( 2 ) collides with the rectangular plate  17 , velocity temporarily drops to zero. With dynamic pressure reaching zero, the static pressure increases and the pressure rises. The high pressure flow reverses and flows toward point P 6  because of the low pressure at P 6  (same pressure as at point P 2 ). The velocity then decreases because the flow passage at point P 7  suddenly becomes wider. 
         [0058]    The flow shown by arrow ( 2 ) is accompanied by losses due to collisions, reversions, and changes in direction, and the velocity is lower than that of the flow shown by arrow ( 1 ). As a result, an asymmetrically offset discharge flow forms as shown in  FIG. 7B . 
         [0059]    As is made clear by  FIG. 7A , an asymmetrically offset discharge flow can also be obtained by changing the rectangular plate  17  to a square plate or a disk. However, as described with reference to  FIG. 2 , the rectangular plate  17  is preferred over a square plate or a disk. 
         [0060]    If the long side of the rectangular plate  17  is less than twice the length of the short side, e.g., 1.5 times the length, the shape approaches that of a square plate, and a strong offset cannot be obtained. If the long side is more than twice the length of the short side, e.g., three times the length, a strong offset is obtained, but the overall resistance in the flow passage increases, and the cost of powering the sealer application pump increases as well. Therefore, a length-to-width ratio of 2:1 for the rectangular plate  17  is preferred. 
         [0061]    Following is a description of a sealing nozzle of a second embodiment shown in  FIG. 8 . 
         [0062]    The sealing nozzle  20 B shown in  FIG. 8  comprises a pipe  21  for transporting a sealer, a flattened tubular part  23  provided to the distal end of the pipe  21  and used to discharge the sealer from an oblong opening  22  in the distal end, and a guide member  24  that stretches out from the pipe  21  (or the flattened tubular part  23 ) and is used to guide the flattened tubular part  23  toward an application part of a coating workpiece by following the coating workpiece. A center line  28  of the flattened tubular part  23  is displaced by  6  from the center line  29  of the pipe  21  toward the guide member  24 . 
         [0063]    The volume of flow on the side of the guide member  24  can be reduced and an asymmetrical flow can be produced by the displacement δ. 
         [0064]    Following is a description of a sealing nozzle of a third embodiment shown in  FIG. 9 . 
         [0065]    The sealing nozzle  20 C shown in  FIG. 9  comprises a pipe  21  for transporting a sealer, a flattened tubular part  23  provided to the distal end of the pipe  21  and used to discharge the sealer from an oblong opening  22  in the distal end, and a guide member  24  that stretches out from the pipe  21  (or the flattened tubular part  23 ) and is used to guide the flattened tubular part  23  toward an application part of a coating workpiece by following the coating workpiece. The area (the dotted line portion) of the flattened tubular part  23  near the guide member  24  is sunk in toward the sealer passage  22 , forming a salient part  3   1 . The salient part  31  can also be regarded as a depression formed so as to be sunk in from the exterior to the interior of the flattened tubular part  23 . 
         [0066]    When a portion (the salient part  3   1 ) where such a flow of the sealer is restricted occurs in an area near guide member  24 , the sealer that flows out of the oblong opening  22  is truncated on the side near the guiding portion  24 . In this way, the overcoated portion can be eliminated and cleanup or other aftertreatment can be omitted in the third embodiment. 
         [0067]    In addition, because the flattened tubular part  23  is merely sunk in locally, there is no need to provide separate components, and the cost of material can be kept from rising. 
         [0068]      FIG. 10  shows a flowchart that explains the process of manufacturing a vehicle body. 
         [0069]    Referring to  FIG. 10 , the above manufacturing process has a pressing step for pressing a blank (ST 01 ); a welding step for stacking and welding steel sheets that have been pressed together (ST 02 ); a coating pretreatment step for removing weld spatter, oil, and other contaminants to prepare for coating (ST 03 ); and an electrodeposition coating step for forming an undercoating (ST 04 ). A semi-finished part of a vehicle body (for example, a rear door mounted on a center pillar) such as the one shown in  FIGS. 11A and 11B  is obtained as a result of the above steps. A sealer is applied (ST 05 ) to the work area of the two steel sheets in the semi-finished part of a vehicle body, the main coating is applied in a coating step (ST 06 ), and the part is sent to an assembly line. 
         [0070]      FIGS. 11A and 11B  show the sealer application step according to the present invention. 
         [0071]    The sealing nozzle  20  shown in  FIG. 11A  comprises a pipe  21  for transporting a sealer, a flattened tubular part  23  provided to the distal end of the pipe  21 , and a guide member  24  that stretches out from the pipe  21  or the flattened tubular part  23 . The flow of the sealer in the flattened tubular part  23  in proximity to the guide member  24  is slower than the flow in a portion distant from the guide member. 
         [0072]    Let us assume that the object of sealer application is a rear door  35  fastened by a door hinge  34  to a center pillar  33 . In the rear door  35 , an inner plate  36  is superposed with an outer plate  37  as two steel sheets, and the edge part of the outer plate  37  is bent back onto the inner plate  36  to form a unified construction. 
         [0073]    A sealer  15  must be applied to an overlapping area  38  of the rear door  35 . 
         [0074]    At this point, the distal end of the sealing nozzle  20  is lined up with the boundary  41  of an overlapping area  35  while the guide member  24  is made to follow the edge part  39  of the rear door  35  in  FIG. 11A . 
         [0075]    In  FIG. 11B , the sealing nozzle  20  is slowly moved while the sealer  15  is discharged from the sealing nozzle  20 , whereupon the boundary line  41  is coated with the sealer  15 . The sealer  15  is applied accurately without any overcoating. 
         [0076]    Specifically, the sealer  15  is prevented from protruding outside the vehicle body (rear door  35 ) when the operation to apply the sealer is started. As a result, labor involved in applying the sealer in the manufacturing of a vehicle body can be reduced. Overcoating causes increased water leaks and air cutting noise, as well as formation of rust and crevices. Because such overcoating can be removed in accordance with the present invention, formation of water leaks in the vehicle body can be prevented, the air cutting noise can be reduced, the formation of rust on the vehicle body can be prevented, and the infiltration of dirt into the vehicle body can be prevented as well. 
         [0077]    In addition to a vehicle door, the sealing nozzle of the present invention can also be used to apply a sealer to a hood or a vehicle body. 
         [0078]    Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.