Abstract:
A device for assembly of a flexible conduit element consisting essentially of a flexible ring-corrugated or helical-shaped bellows body which is displaced over an inner arbor in order to introduce a jacket into the corrugations of the bellows body, has an the inner arbor comprising actuating elements for engagement into the corrugations of the bellows body at an inner side thereof. The inner arbor has an axial length which can be adjusted.

Description:
This application is a continuation-in part of Ser. No. 09/453,090 filed Dec. 2, 1999 now abandoned and claiming Paris Convention priority of DE 198 56 513.5 filed Dec. 8, 1998 the complete disclosure of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention concerns a device for assembly of a flexible conduit element comprising a flexible ring-corrugated or helical-shaped bellows member and a surrounding jacket cooperating therewith and having an inner arbor penetrating through the bellows member. 
     Devices of this type are used for the assembly of flexible conduit elements such as metallic exhaust tubes. These types of conventional conduit elements (U.S. Pat. No. 5,769,643, FR 2 685 435) primarily serve for the acceptance of vibrations to prevent their transmission from a rigid component to a neighboring component. The conduit elements thereby preferentially comprise a bellows member having a corrugated or helical structure and a jacket surrounding same made from a woven or knitted material which is captured by rings of the bellows member and which damps characteristic vibrations of the bellows member. 
     During conventional manufacture of an element of this type comprising a bellows body and an outer woven or knitted tube or conduit element, the latter had been displaced over the free bellows and fixed at the outside between the rings of the bellows body. The bellows body had been disposed on an inner arbor during this assembly procedure. 
     This procedure has the substantial disadvantage that attachment of the jacket to the bellows body is performed in an undefined fashion and substantial tolerance fluctuations in length can occur. The free disposition of the highly flexible bellows body on the inner arbor can preclude a defined cutting to length of the bellows body and essentially prevents a plane parallel cut when cutting to length. 
     DE 42 02 808 A1 discloses a flexible conduit element for exhaust conduits having a ring-corrugated or helical bellows and a metal tube disposed therein, the ends of which are connected with the ends of the bellows to connectors for the exhaust conduit. This product has been manufactured by initially cutting the bellows and the metallic tube to the desired length. The ends of the sectioned bellows or metal tube are provided with a support ring and the bellows and the metal tube are combined after disposition of a ring-shaped drive element on the ends. A conduit element of this kind, preassembled in this fashion, is placed in or on a magnetic coil for concentric centering of the bellows and metallic tube and, in order to bridge the separation between the bellows and the metallic tube, the metallic tube is widened against the inner wall of the outer support ring while the corrugations of the bellows are pushed together and the individual layers of the various components are pressed together and/or the corrugations of the bellows and the agraff structure of the metal tube are pressed together against the outer wall of the inner support ring or of a support arbor penetrating through the support ring. A pre-assembled conduit element is preferentially inserted into a magnetic pulse device and the differing components are pressed together by electrically conducting drive elements using the magnetic pulse procedure. 
     It is the underlying purpose of the invention to propose a device for the assembly of a flexible conduit element with which the above mentioned disadvantages are avoided. 
     SUMMARY OF THE INVENTION 
     This purpose is achieved in accordance with the invention in the device of the above mentioned kind in that the inner arbor has elements for engaging into the bellows body, wherein the length of the inner arbor can be adjusted. The elements of the inner arbor engaging into the bellows body thereby fix the location of the bellows body relative thereto i.e. to prevent displacement of the bellows body on the inner arbor during placement of the jacket. In addition, the inner arbor has a length which can be adjusted to thereby facilitate setting of the length of the bellows body to a predetermined preferred value. 
     In a preferred embodiment, the elements engage the corrugated portions of the bellows body at the ends thereof to thereby subject the individual corrugated sections to a substantially even tensile and compression forces so that the separation between the individual corrugations relative to each other remains substantially constant. 
     Advantageously, the elements for engagement into the end corrugations of the bellows body are pawls which engage in a positive connecting fashion into a corrugation of the bellows body with at least one outwardly projecting collar member to thereby serve as a holding or carrier element therein. 
     Advantageously, the pawls are borne for pivoting on the inner arbor so that they can be pivoted from an inactive position into an active position in cooperation with the spreading arbor and vice versa. 
     Further advantages and features of the invention can be extracted from the following description with reference to the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a longitudinal section through a substantially cylindrical fixture in accordance with the invention, following initial insertion within a bellows; 
     FIG. 2 is a second section depicting the fixture of FIG. 1 in a second position in which pawls have been pivoted to engage into end portions of the bellows; and 
     FIG. 3 is a third section through the fixture of FIGS. 1 and 2 in a third stage in which the bellows has been stretched through extension of the fixture. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The device for assembling a flexible bellows conduit element comprises a fixture  2  for insertion within a bellows  4 . The fixture  2  comprises an inner guide member  5  having a substantially cylindrical guide surface  7  and a plunger abutment surface  8 . A central bore  10  penetrates through the inner guide member  5 . A forward face of the inner guide member  5  has integral first and second guide protrusions  12  and  13 , disposed proximate to an inner surface of the bellows  4 . A first guide pawl  16  is mounted to the first guide protrusion  12  for rotation relative thereto to pivot in an outward direction towards the bellows  4 . A first guide torsion spring  14  biases the pawl in a radially inward direction to assume the position shown in FIG.  1 . The first guide pawl  16  has an end on which a first guide pawl nose  17  is disposed. In the embodiment of FIG. 1, a second guide pawl  18  is disposed diametrically across from the first guide pawl  16  and mounted for rotation to the second guide protrusion  13 . A second guide torsion spring  15  biases the second guide pawl  18  in a radially inward direction to assume the position shown in FIG. 1. A second guide pawl nose  19  is disposed at the end of the second guide pawl  18  and is directed, as is the first guide pawl nose  17  of first guide pawl  16 , in a substantially radially outward sense. 
     The fixture further comprises a plunger  20  having a plunger rod  22  extending in a forward direction to penetrate through the central bore  10  of the inner guide member  5 . A forward portion of the plunger  20  is provided with a plunger disk  24  attached to the plunger rod  22  with suitable attachment means  26 . The plunger disk  24  extends in a substantially radial direction to abut against radially inner surfaces of the first guide pawl  16  and of the second guide pawl  18  in the position shown in FIG.  1 . The plunger  20  also has a plunger collar  28  positioned at a rear portion thereof and having a substantially cylindrical collar surface  29 . 
     A cylindrical outer sleeve member  40  is disposed about the plunger  20  and the guide surface  7  of the inner guide member  5 . The outer sleeve member  40  comprises an integral sleeve shoulder  42  disposed at a portion of the outer sleeve member  40  most proximate to the first  16  and second  18  guide pawls. A sleeve tube  44  extends from the sleeve shoulder  42  towards a rear direction and has an upwardly disposed first sleeve slot  46  and a diametrically positioned second sleeve slot  48 . A first sleeve pawl  50  is mounted for rotation within the first sleeve slot  46  to pivot in a radially outward direction. The first sleeve pawl  50  has a first sleeve pawl nose  52  directed in a substantially outward sense. A diametrically opposed second sleeve pawl  54  is accommodated within the second sleeve slot  48  for pivoting in an outward direction. The second sleeve pawl  54  has a second sleeve pawl nose  56  pointing radially outward. First sleeve torsion spring  58  and second sleeve torsion spring  60  bias the first sleeve pawl  50  and second sleeve pawl  54 , respectively, in an inward direction to assume the position shown in FIG.  1 . 
     The function of the fixture in accordance with the invention will now be described in connection with FIGS. 1,  2  and  3 . In an initial stage, the fixture  2  is prepared for insertion into the bellows  4  by detaching the plunger disc  24  from the plunger rod  22  through disengagement of disc attachment means  26 . The outer sleeve member  40  is then displaced over the guide surface  7  of the inner guide member  5  to assume the position shown in FIG.  1 . Subsequent thereto, the plunger  20  is inserted from the rear within the outer sleeve member  40  such that the plunger rod  22  penetrates through the central bore  10  of the inner guide member  5  to exit at the front portion thereof, as shown in FIG.  1 . The plunger disc  24  is then reattached to the plunger rod  22  using disc attachment means  26 . The completely assembled fixture is then inserted within the bellows  4  to assume the position illustrated in FIG.  1 . 
     In a second stage, illustrated in FIG. 2, the plunger  20  is displaced in a forward direction until a front end of the plunger collar  28  abuts against the plunger abutment surface  8  of the inner guide member  5 . As a result thereof, the plunger disc  24  is displaced in a forward direction to pivot the first guide pawl  16  and second guide pawl  18  in opposition to the biasing force of the first guide torsion spring  14  and the second guide torsion spring  15  and into the position shown in FIG.  2 . The first guide pawl nose  17  and second guide pawl nose  19  are disposed within an end corrugation of the bellows  4  and captured therein. At the same time, the outer surface  29  of the plunger collar  28  engages the first sleeve pawl  50  and second sleeve pawl  54  causing them to pivot in opposition to the bias force of first sleeve torsion spring  58  and second sleeve torsion spring  60  to rotate through the first sleeve slot  46  and second sleeve slot  48  to assume the position shown in FIG.  2 . The first sleeve pawl nose  52  and second sleeve pawl nose  56  thereby engage into end corrugations of the bellows  4 . In the position shown in FIG. 2, the bellows is firmly captured at its forward and rear ends through the engagement of first guide pawl nose  17 , second guide pawl nose  19 , first sleeve pawl nose  52 , and second sleeve pawl nose  56 . 
     In a third stage of procedure in accordance with FIG. 3, the outer sleeve member  40  is displaced away from the first and second guide pawls  16  and  18  to slide along the guide surface  7  until the sleeve shoulder  42  abuts against a front surface of the plunger collar  28  diametrically proximate the plunger abutment surface  8 . The collar surface  29  is dimensioned in such a fashion that contact is maintained between this surface  29  and the first sleeve pawl  50  as well as the second sleeve pawl  54  such that the first sleeve pawl nose  52  as well as the second sleeve pawl nose  56  remain engaged in end corrugations of the bellows  4 . Since the relative position between the plunger  20  and the inner guide member  5  does not change during this latter procedure, the plunger disc  24  continues to displace the first guide pawl  16  and second guide pawl  18  such that the first and second guide pawl noses  17  and  19  remain engaged in end corrugations at the front portion of the bellows  4 . This position can be maintained by using conventional clamping techniques active on portions of the outer sleeve member  40  extending beyond the bellows  4 . The bellows  4  is thereby stretched in preparation for the introduction of a surrounding jacket made from a woven or knitted material (not shown in the figure). 
     Subsequent to application of the surrounding jacket, the steps described in connection with FIGS. 1,  2  and  3  are reversed such that the bellows  4  relaxes from the stretched position of FIG. 3 to the initial position shown in FIG. 1 to capture the corrugated or helical woven or knitted material of the jacket within the corrugations of the bellows  4 . 
     LIST OF REFERENCE SYMBOLS 
       2  fixture 
       4  bellows 
       5  inner guide member 
       7  guide surface 
       8  plunger abutment surface 
       10  central bore 
       12  first guide protrusion 
       13  second guide protrusion 
       14  first guide torsion spring 
       15  second guide torsion spring 
       16  first guide pawl 
       17  first guide pawl nose 
       18  second guide pawl 
       19  second guide pawl nose 
       20  plunger 
       22  plunger rod 
       24  plunger disc 
       26  disc attachment 
       28  plunger collar 
       29  collar surface 
       40  outer sleeve member 
       42  sleeve shoulder 
       44  sleeve tube 
       46  first sleeve slot 
       48  second sleeve slot 
       50  first sleeve pawl 
       52  first sleeve pawl nose 
       54  second sleeve pawl 
       56  second sleeve pawl nose 
       58  first sleeve torsion spring 
       60  second sleeve torsion spring