Abstract:
Two components ( 2, 3 ) to be joined to each other by vibration welding form on one or both sides of the bounding seam ( 10 ) barrier means ( 20 ) including a labyrinth seal. Means ( 20 ) retaining attrition particles of the jointing faces ( 16, 17 ) in chambers ( 25, 26, 27 ) by the attrition particles needing to migrate from chamber to chamber through damming gaps ( 21, 22 ) and to be deflected for passage through the next gap in each case. Due to this tortuous arrangement the attrition particles remain totally within the chamber system of the labyrinth seal ( 20 ) and do not emerge from between the flanges ( 8, 9 ). When the seal ( 20 ) is provided between the seam ( 10 ) and the inner face ( 6 ) of a container, the interior thereof is thus protected from soilage due to attrition particles.

Description:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a jointing unit for jointing seams, particularly seams supplying migratable material which may escape from between the opposed jointing zones or flange faces. Such material may be jointing material formed directly by the jointing flanges, i.e. solids such as particles capable of escaping laterally from between the jointing faces. 
     In the production of fusion or welded joints on components of plastics or the like the energy needed to melt the jointing material may be achieved by causing the jointing faces to be rubbed against each other by oscillation until they weld together. In this arrangement the jointing faces are rubbed together at a speed of 500 to 1000 mm per second for 2 to 8 secs at an oscillation frequency of 85 to 250 Hz and at an oscillation amplitude of 0.5 to 2 mm. The jointing faces are initially rubbed off by a depth of approx. 0.5 to 1 mm before then being melted off. Thereby the jointing faces are correspondingly approached toward each other. 
     Before the melting temperature is attained attrition particles are generated during the solid friction phase. These particles are required to remain between the flange faces. If the two components or dishes having annularly uninterrupted jointing flanges, flange faces or jointing faces are joined together by the seam to form a tank or container the cited attrition material must not gain access to the interior of the tank irrespective of how long the tank is in operation. Otherwise the contents of the tank would be soiled. 
     This applies especially to automotive fuel tanks whose communicating conduits from the tank to the combustion chamber would be choked up by such particles. Although the interior of the tank could be cleaned out after the joint has been made, this is, however, extremely complicated and hardly achievable with full success. Even in the case of a concealed seam there is no absolute guarantee that fine to very fine solids particles are not expelled from between the coverings of the flange faces and gain access to the large faces of the walls interconnected by their flanges. 
     OBJECTS OF THE INVENTION 
     An object is to provide a jointing unit which avoids the disadvantages of known configurations or of the aforementioned kind. Another object is to prevent on one or both outer sides of the sealing seam the escape of the cited material from between the flange faces. A still further object is, that the jointing flanges, particularly the flange faces, are simple in structure and handling. 
     SUMMARY OF THE INVENTION 
     According to the invention means are provided to prevent migration of most of the cited material or every material towards at least one side out of the jointing gap between the flange faces. Such means may comprise one or more chambers for receiving the material between the flange faces or at least one seal for preventing coming forth of the material. 
     This seal is preferably a labyrinth seal. The sealing members of the two flanges do not come into contact with each other or, at the most, without any significant pressing. They do not rub against each other to such an extent that attrition materializes. The narrowest gaps of the seal may be at least 0.2 or 0.4 mm. The associated gap planes are parallel to the jointing faces and thus to the direction of vibration. The flanks of the sealing members directly mutually opposed remain out of contact during the vibration or come into contact but with no significant pressure. 
     It is particularly expedient when the chamber directly adjoining the jointing faces is larger than the next chamber or the one more remote from the jointing faces which may adjoin the larger chamber via a sealing point. The width of the larger chamber as measured parallel to the vibration motion is sufficiently large so that the associated side faces remain spaced from each other even in closest approximation during vibration. Thus space remains for receiving the material even with the most constricted chamber. Accordingly, the material is not expelled from this chamber into the next chamber or only in negligable amounts. When a transfer of material into the next chamber occurs, it remains captured there just the same as in the larger chamber during all the time the welded item is in use. 
     Due to the sealing points the stored medium is unable to be flushed out of the side joint gaps of the seam. The retention or damming gap or all damming gaps is/are narrower than the jointing faces. In cross-section the jointing gap may form at each outside a narrow sealing gap. Between the sealing gap and the jointing faces at least two or three chambers and at least one or two sealing gaps are provided which are expediently displaced transversely to each other and/or to the jointing faces. 
     It is particularly expedient when the sealing gap is narrower than the narrowest jointing face or seam. The sealing gap can then be bounded by a web or a rib, the thickness of which is max. 2 or 1 mm. As a result the web may also pivot about its root and execute resilient tilt motions, e.g. give place to the material on a constriction of the chamber and thus adapt the minimum chamber size to the chamber contents without attrition generating at the web. 
     The chambers which are closed or open only in the vicinity of the sealing gaps are configured to be not symmetrical relative to the center plane. This plane of the jointing faces is perpendicular to the jointing faces. Particularly between the outside of the jointing gap to be protected from emission and the jointing faces more or larger chambers or more sealing gaps may be provided than at the other side. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Example embodiments of the invention are explained in more detail in the following and illustrated in the drawings in which: 
     FIG. 1 is a cross-sectional view of the jointing unit according to the invention, 
     FIG. 2 is a cross-sectional view of a further jointing unit illustrated greatly magnified, and 
     FIG. 3 is a cross-sectional view of a further embodiment. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates the jointing unit  1  serving for non-detachably weld joining two tray-shaped components  2 ,  3  of thermoplastics material to a sealed tank by means of vibration welding. The energy required to melt off the plastics is generated by direct mutual friction of the bordering or jointing faces. On commencement of this oscillatory friction, namely in the solid friction phase, the jointing faces are still solid. This is followed by an initially instationary and then a stationary friction phase in which the jointing faces form a common film of plastics melt providing the jointing material. This is followed by the last phase, the cooling phase, in which the jointing material and thus the weld solidifies. Components  2 ,  3  form container walls  4 ,  5  of the container with inner faces  6  and outer faces  7 . The inner faces  6  and the outer faces  7  respectively are flushingly aligned with each other. 
     Each component  2  or  3  comprises an annular flange  8  or  9  protruding only beyond the outer face  7  at the rim of the associated wall  4  or  5 . The two flange s  8 ,  9  are connected to each other via a concealed welding or bonding seam  10  located in a seam plane  11  at right angles to walls  4 ,  5 . The center plane  12  of the seam  10  is outwardly spaced from outer faces  7  and is radially spaced from face  7  more than from the outer circumference of flanges  8 ,  9 . The center plane  13  between flanges  8 ,  9  which is perpendicular to the flange axes  3  and parallel to seam plane  11  is spaced from seam plane  11 . The direction  14  of the welding vibration is parallel to planes  11 ,  13 . During vibration, pressure is exerted on the one flange  8  at right angles to planes  11 ,  13  in direction  15 . Thus flange  8  is pressed against the other flange  9  wich is counter supported. 
     During vibration and pressing action only the concealed jointing faces  16 ,  17  of flanges  8 ,  9  come into contact with each other. Faces  16 ,  17  are annular while in cross-section being located in the same center plane  12 . Face  16  of flange 8 is 1 mm wider than face  17  of flange  9 . The jointing zone of field  18 , namely the overall extension of seam  10  is thus the same as that of face  17 . 
     In the solid friction phase solid particles or jointing material  19  are abraded from faces  16 ,  17 . The particles emerge laterally from between faces  16 ,  17  into the space between flanges  8 ,  9  and tend to be expelled up to inner face  6  during further vibration. To prevent this happening retention or barrier means  20 , namely a labyrinth seal, are provided. Means  20  comprise between field  18  and inner face  6  three damming gaps  21 ,  22 ,  23  spaced from each other. A chamber  25  or  26  or  27  is bounded by flanges  8 ,  9  and between two gaps. The gaps and chambers are annular and are nested concentrically. The width of the gaps amounts to 0.3 mm and max. 1 or 0.5 mm. The breadth  29  of each gap is smaller than the breadth  41  or  42  of each chamber which in turn is smaller than the height extension  40  of each chamber. 
     Jointing face  16  is formed by a jointing web  30  and jointing face  17  by a jointing web  31 , the height of which is less than that of jointing web  30 , for example, 0.3 times the height  45  of jointing web  30 . Jointing webs  30 ,  31  protrude beyond opposed faces of flanges  8 ,  9 . These faces form the mutually opposed bottom faces  32 ,  33  of all chambers and their bottom planes are parallel to planes  11 ,  13 . Faces  32 ,  33  also in each case form a bound of each gap. Between the outer circumference of flanges  8 ,  9  and the jointing field  18  likewise a damming gap  24  and a chamber  28  are provided. As compared to this side the number of gaps and chambers at the other side is more so that means  20  are configured asymmetrically to plane  12 . Instead of a single gap  24  and a single chamber  28 , however, a configuration may be provided on this side between face  6  and seam  10 , which is the same as already described. 
     Each chamber is bounded by two webs protruding opposingly beyond faces  32 ,  33  and forming the chamber flanks  34  to  37 . Each web adjoins the associated flange  8  or  9  in one part by a root  38 . Each web is constant in thickness up to its free edge face  39  but may translate rounded into edge  39 . In this case the edge  39  of each of the webs may form a planar surface or a totally convexely rounded face. Web edge  39  bounds with the opposite bottom  32  or  33  the associated gap. All gaps are the same in width. 
     Chamber  25  directly adjoining seam  10  is bounded by webs  30 ,  49 . Next chamber  26  is bounded by webs  48 ,  49  and last chamber  27  is bounded by webs  48 ,  50 . This chamber  27  directly adjoins face  6  via gap  23 . Web  49  is located between webs  30 ,  48  and protrudes contrary thereto. Web  48  is located between webs  49 ,  50  and protrudes contrary thereto. Thus gaps  21 ,  23 ,  24  are located in a first gap plane  43  and a sole gap  22  in a second gap plane  44 . Both gap planes  43 ,  44  are parallel to planes  11 ,  13  but located at their remote sides. Plane  43  is located at bottom  32  and plane  44  at bottom  33 . Thus gaps  21 ,  23 ,  24  are more remote from plane  11  than gap  22 . Both planes  43 ,  44  are equidistant from plane  13 . 
     The jointing material  19  emerging from between faces  16 ,  17  needs to migrate from bottom  33  upwards over the full chamber height  40  into chamber  25  or  28  to gain access to next gap  21  or  24  respectively. When some of the material  19  is urged through gap  21 , then this material needs to migrate downwards over the height  40  to gain access to next gap  22 . Should some of the material  19  also gain access through this gap  22  it is deposited in chamber  27  before it could pass through gap  23 . Where necessary, the number of gaps and chambers can be further increased. Although attrition particles can be deposited in all chambers, the arrangement is such that the last chamber  27  remains empty and thus the contents of the tank are unable to flush out the particles from the chambers. Each chamber forms an intercepting duct in which the particles can also be distributed longitudially throughout the chamber length. 
     The thickness  29  of all webs  48  to  51  is the same and not more or smaller than the width of field  18  or the thickness of webs  30 ,  31 . Thereby the thickness  29  may amount to maximally 3 or 2 or 1.5 mm. This thickness equals the width of each gap. Flanks  34  to  36  of the webs are perpendicular to planes  11 ,  13 . Thus each chamber is bounded by parallel and opposed chamber flanks. The spacing between the chamber flanks is given by the chamber breadth  41  or  42 . The breadth  42  of chamber  26  or  27  equals the vibration path amounting to 1 or 2 mm. The breadth  41  of chamber  25  or  28  is larger relative to breadth  42  by half a millimeter. Thus chambers  25 ,  28  directly adjoining seam  10  are not totally closed during vibration. Even when chamber  25  or  28  is most constricted a residual volume remains free to receive all attrition particles without any significant densification. Chambers  26 ,  27  may be totally closed alternately during vibration by their flanks coming into mutual contact, but here too a residual volume can also remain free. 
     FIG. 2 illustrates how web  48  is able to also enter by its end or edge  39  a recess  53  in the associated chamber bottom  32  or  33  and to sealingly contact the bounds of this recess. This contact may be a positive abutting of edge  39  in direction  15  as aparent from FIG. 2 or it may be a contact of the web flanks with the flanks of the recess permitting mutual sliding motion parallel to direction  15 . Since on vibration flanges  8 ,  9  are approximated at faces  16 ,  17  corresponding to formation of the melt, edge  39  in the first case comes into contact with recess  53  not before the end of vibration whereas in the second case already at the beginning of vibration web  48  may sealingly engage the recess, for example, a groove. 
     To nevertheless permit vibrational motion the web root  38  acts as a bending hinge about which those longitudinal sections of web  48  which are oriented transverse to direction  14  pivot oscillatingly. The longitudinal sections oriented parallel to direction  14  execute no such pivotal motions. The chambers bounded by these longitudinal sections are also not constricted or widened. In any case the connection between web  48  and recess  53  is selected so that no attrition occurs due to the relative motions. Each of the other webs  49  to  51  like web  48  is able to engage the opposing flange. 
     Adjoining the outer circumference, each flange  8  or  9  comprises a reinforcement web or member  46 , for example, a rib spaced from wall  4  and  5  respectively and protruding beyond the flange side facing away from seam  10 . With the outer face  7  the annular web  46  bounds a groove  47 . The bottom of groove  47  is parallel to planes  11 ,  13  and serves to receive the compressive force in direction  15  or the opposingly oriented counter force. In groove  47  the corresponding tool of the vibration welding machine can be reliably received without contacting wall  4  or  5 . 
     FIG. 3 illustrates how only two chambers  25 ,  27  and a single gap  21  are provided between seam  10  and gap  23  whilst three chambers and two gaps are provided in FIGS. 1 and 2. Gap  23  is transversely offset from plane  43  of gap  21  and is located in the middle of chamber height  40 , i.e. in plane  13 . For this purpose none of the bounds of gap  23  is formed by one of bottom faces  32 ,  33 . Instead both bounds are formed by webs  50 ,  52 , each of which protrudes beyond the associated bottom face  32  or  33  and is equal in height. Both webs  50 ,  52  form inner face  6 . 
     The method in accordance with the invention prevents by simple ways and means attrition particles or other material from emerging between the flange faces at the one or other side of wall  4 ,  5 . Prior to welding, components  2 ,  3  are cleaned of particles before being layed separately into the tools of the welding machine by which they are then put together so that only faces  16 ,  17  come into mutual contact. Since webs  30 ,  31  are still higher at first, gaps  21  to  24  have their greatest width. Vibration is then applied, resulting in the faces  16 ,  17  being rubbed against each other and heated up due to friction until the melting temperature of the plastics material is attained. Due to the pressure the webs  30 ,  31  are reduced in height until the desired gap width is attained. Once seam  10  has cooled down unit  1  is removed from the tools. 
     It is understood that all features of each embodiment may be provided in any other embodiment. Also, each damming gap, each chamber or each web may be configured like any of the other corresponding arrangements. The features and effects or dimensions may be provided precisely or merely substantially or roughly as described and may also greatly deviate therefrom, depending on the requirements.