Induction connection sleeve

Abstract

The invention relates to an induction connection sleeve ( 1 ) for fusion joining of plastic pipes ( 2, 3 ). The induction connection sleeve ( 1 ) comprises a sleeve body ( 9 ) having a first ( 5 ) and a second receiving portion ( 7 ) for receiving first ( 4 ) and second connection portions ( 6 ) of the plastic pipes ( 2, 3 ) to be connected, a first induction heating element ( 12 ) and a second induction heating element ( 13 ). The sleeve body ( 9 ) comprises an inner part ( 10 ), which inner part ( 10 ) forms the two receiving portions ( 5, 7 ) and on which the induction heating elements ( 12, 13 ) are accommodated in such a way that the recesses ( 16 ) of the induction heating elements ( 12 ) are penetrated by the inner part ( 10 ) and are flush at their outer lateral surfaces ( 14, 15 ) with the inner part ( 10 ) in the area of the induction heating elements ( 12, 13 ). The sleeve body ( 9 ) further comprises an outer part ( 11 ) which is connected to the inner part ( 10 ) in a bonded manner and surrounds the outer lateral surfaces ( 14, 15 ) of the induction heating elements ( 12, 13 ).

1 - 16 . (canceled) 
     
     
         17 . An induction connection sleeve ( 1 ) for connecting by fusing plastic pipes ( 2 ,  3 ), comprising:
 a sleeve body ( 9 ) from an injection-molded thermoplastic plastics material, having a first ( 5 ) and a second receptacle portion ( 7 ) for receiving first ( 4 ) and second connection portions ( 6 ) of the plastic pipes ( 2 ,  3 ) to be connected, said receptacle portions ( 5 ,  7 ) being disposed in a mutually coaxial manner;   a first induction heating element ( 12 ) which is configured in a bush-shaped manner and has recesses ( 16 ) that are disposed in the circumference, said first induction heating element ( 12 ) being embedded in the sleeve body ( 9 ), wherein the first induction heating element ( 12 ) surrounds the first receptacle portion ( 5 ) of the sleeve body ( 9 ); and   a second induction heating element ( 13 ) which is configured in a bush-shaped manner, and has recesses ( 16 ) arranged in the circumference said second induction heating element ( 13 ) being embedded in the sleeve body ( 9 ), wherein the second induction heating element ( 13 ) surrounds the second receptacle portion ( 7 ) of the sleeve body ( 9 );   wherein the sleeve body ( 9 ) comprises an internal part ( 10 ), said internal part ( 10 ) configuring the two receptacle parts ( 5 ,  7 ), and the induction heating elements ( 12 ,  13 ) being received on said internal part ( 10 ) in such a manner that the recesses ( 16 ) of the induction heating elements ( 12 ) are penetrated by the internal part ( 10 ), said recesses ( 16 ) on the external shell surfaces ( 14 ,' 15 ) thereof in the region of the induction heating elements ( 12 ,  13 ) terminating flush with the internal part ( 10 ), and wherein the sleeve body ( 9 ) comprises an external part ( 11 ) which is connected in a materially integral manner to the internal part ( 10 ) and surrounds the external shell surfaces ( 14 ,  15 ) of the induction heating elements ( 12 ,  13 ), wherein the induction heating elements ( 12 ,  13 ) are entirely enclosed by the internal part ( 10 ) and by the external part ( 11 ).   
     
     
         18 . The induction connection sleeve as claimed in  claim 17 , wherein the internal part ( 10 ) of the sleeve body ( 9 ) is formed from a first plastics from the group of thermoplastic plastics which has a first melting point, and wherein the external part ( 11 ) of the sleeve body ( 9 ) is formed from a second plastics, different from the first plastics, from the group of thermoplastic plastics which has a second melting point, wherein the melting point of the second plastics is higher than the melting point of the first plastics. 
     
     
         19 . The induction connection sleeve as claimed in  claim 17 , wherein an adhesive agent layer ( 38 ) is configured between the internal part ( 10 ) and the external part ( 11 ). 
     
     
         20 . The induction connection sleeve as claimed in  claim 17 , wherein a continuous receptacle portion ( 17 ) having a cylindrical internal shell surface ( 18 ) for receiving connection portions ( 4 ,  6 ) of the plastic pipes ( 2 ,  3 ) to be connected is configured on the internal part ( 10 ), wherein the first and the second receptacle portion ( 7 ) are configured in the continuous receptacle portion ( 17 ). 
     
     
         21 . The induction connection sleeve as claimed in  claim 17 , wherein an external shell surface ( 41 ) of the external part ( 11 ) is configured so as to emanate from the longitudinal center of the sleeve body ( 9 ) and taper in the direction toward an end face ( 44 ,  45 ) of the sleeve body ( 9 ). 
     
     
         22 . The induction connection sleeve as claimed in  claim 17 , wherein the wall thickness ( 32 ) of the induction heating element ( 12 ) is between 40% and 60% in relation to the wall thickness ( 39 ) of the internal part ( 10 ) of the sleeve body. 
     
     
         23 . The induction connection sleeve as claimed in  claim 17 , wherein the width ( 47 ,  48 ) of the first ( 12 ) and the second induction heating element ( 13 ) is between 25% and 35% in relation to a width ( 46 ) in the axial direction of the sleeve body ( 9 ). 
     
     
         24 . The induction heating element as claimed in  claim 17 , wherein at least one position-securing element ( 22 ) is disposed on the sleeve body ( 9 ), said position-securing element ( 22 ) in relation to one of the receptacle portions ( 5 ,  7 ) being disposed so as to project radially in the direction toward the center of the sleeve body ( 9 ). 
     
     
         25 . A method for producing an induction connection sleeve ( 1 ), in particular an induction connection sleeve ( 1 ) as claimed in  claim 17 , wherein the production method comprises the following method steps:
 laying up a first induction heating element ( 12 ) in a first injection-mold half ( 50 ), wherein the first injection-mold half ( 50 ) has a first molding cavity ( 52 ) for receiving the first induction heating element ( 12 ), said first molding cavity ( 52 ) having an available diameter ( 53 ) which corresponds to the external diameter ( 28 ) of the first induction heating element ( 12 ), wherein the first induction heating element ( 12 ) is received in a positioned manner in the first injection-mold half ( 50 );   laying up a second induction heating element ( 13 ) in a second injection-mold half ( 51 ) that interacts with the first injection-mold half ( 50 ), wherein the second injection-mold half ( 51 ) has a second molding cavity ( 54 ) for receiving the second induction heating element ( 13 ), said second molding cavity ( 54 ) having an available diameter ( 55 ) which corresponds to the external diameter ( 30 ) of the second induction heating element ( 13 ), wherein the second induction heating element ( 13 ) is received in a positioned manner in the second injection-mold half ( 51 );   mutual compressing of the first ( 50 ) and the second injection-mold half ( 51 ), wherein the first ( 50 ) and/or the second injection-mold half ( 51 ) have/has a first mold core ( 56 ) which for receiving the induction heating elements ( 12 ,  13 ) is disposed so as to be centric to the molding cavities ( 52 ,  54 ) and serves for molding a first ( 5 ) and a second ( 7 ) receptacle portion of the induction connection sleeve ( 1 );   injecting a thermoplastic plastics material into the first ( 52 ) and the second molding cavity ( 54 ), wherein an internal part ( 10 ) of a sleeve body ( 9 ) of the induction connection sleeve ( 1 ) is formed, said internal part ( 10 ) in the internal side having the first ( 5 ) and the second receptacle portion ( 7 ), and the induction heating elements ( 12 ,  13 ) at least in regions being embedded in said internal part ( 10 ), wherein recesses ( 16 ) that are disposed in the circumference of the induction heating elements ( 12 ,  13 ) are penetrated by the plastics material of the internal part ( 10 );   opening the first ( 50 ) and the second injection-mold half ( 51 );   ejecting the internal part ( 10 ) of the sleeve body ( 9 ) having the induction heating elements ( 12 ,  13 ) from one of the injection-mold halves ( 50 ;  51 );   laying up the internal part ( 10 ) of the sleeve body ( 9 ) having the induction heating elements ( 12 ,  13 ) in a third injection-mold half ( 60 ), wherein the third injection-mold half ( 60 ) has a third molding cavity ( 62 ) for receiving the internal part ( 10 ) of the sleeve body ( 9 ), a further mold core ( 64 ) for positioning the internal part ( 10 ) being disposed in said third molding cavity ( 62 ), and wherein a radial gap ( 66 ) for molding an external part ( 11 ) of the sleeve body ( 9 ) is configured between the external circumference of the internal part ( 10 ) and the third molding cavity ( 62 );   closing the third molding cavity ( 62 );   injecting a thermoplastic plastics material into the third molding cavity ( 62 ), wherein an external part ( 11 ) of the sleeve body ( 9 ) is formed;   opening the third molding cavity ( 62 ); and   ejecting the finished induction connection sleeve ( 1 ).   
     
     
         26 . The method for producing an induction connection sleeve ( 1 ) as claimed in  claim 25 , wherein a fourth injection-mold half ( 61 ) having a fourth molding cavity ( 63 ) is provided for closing the third molding cavity ( 62 ), said fourth molding cavity ( 63 ) interacting with the third molding cavity ( 62 ) of the third injection-mold half ( 60 ). 
     
     
         27 . The method for producing an induction connection sleeve ( 1 ) as claimed in  claim 26 , wherein the first ( 50 ) and the third injection-mold half ( 60 ) are disposed on a common clamping plate, and wherein the second ( 51 ) and the fourth injection-mold half ( 61 ) are disposed on a common clamping plate, wherein the first ( 50 ) and the third injection-mold half ( 60 ) form a nozzle side, and the second ( 51 ) and the fourth injection-mold half ( 61 ) form an ejector side and are moved simultaneously. 
     
     
         28 . The method for producing an induction connection sleeve ( 1 ) as claimed in  claim 25 , wherein the ejecting of the internal part ( 10 ) of the sleeve body ( 9 ) having the induction heating elements ( 12 ,  13 ) molded thereon and/or ejecting the finished induction connection sleeve ( 1 ) are/is carried out by means of ejectors ( 67 ) which are disposed in one of the injection-mold halves ( 50 ,  51 ,  60 ,  61 ). 
     
     
         29 . A method for producing a welded connection between a first plastic pipe ( 2 ) and a second plastic pipe ( 3 ), in particular while using an induction connection sleeve ( 1 ) as claimed in  claim 17 , wherein the method comprises the following method steps:
 providing the first plastic pipe ( 2 );   providing the induction connection sleeve ( 1 ) having a sleeve body ( 9 ) which has a width ( 46 ) in the axial direction;   push-fitting the induction connection sleeve ( 1 ) onto the first plastic pipe ( 2 ) such that the induction connection sleeve ( 1 ) by way of the entire width ( 46 ) of the sleeve body ( 9 ) surrounds the first plastic pipe ( 2 );   providing the second plastic pipe ( 3 );   coaxially aligning the second plastic pipe ( 3 ) in relation to the first plastic pipe ( 2 ) and disposing the former directly next to the latter;   axially displacing the induction connection sleeve ( 1 ) such that the latter in part surrounds the first plastic pipe ( 2 ) and the second plastic pipe ( 3 ); and   positioning an inducing device ( 69 ) in the region of the induction connection sleeve ( 1 ) and by means of the inducing device ( 69 ) inducing a current in the induction connection sleeve ( 1 ) such that the sleeve body ( 9 ) at least in part is plasticized and connects in a materially integral manner to the two plastic pipes ( 2 ,  3 ).   
     
     
         30 . The method as claimed in  claim 29 , wherein for producing a welded connection between double-walled plastic pipes ( 2 ,  3 ), each having one internal pipe ( 70 ,  71 ) and one external pipe ( 72 ,  73 ), prior to the method step of axially displacing the induction connection sleeve ( 1 ) in which the induction connection sleeve ( 1 ) in part surrounds the first plastic pipe ( 2 ) and the second plastic pipe ( 3 ), at least the following method step is additionally carried out:
 welding the two internal pipes ( 70 ,  71 ) of the double-walled plastic pipes ( 2 ,  3 ).   
     
     
         31 . The method as claimed in  claim 30 , wherein the two internal pipes ( 70 ,  71 ) of the double-walled plastic pipes ( 2 ,  3 ) at the end side are welded by heating-element butt welding by means of a welding mirror ( 75 ). 
     
     
         32 . The method as claimed in  claim 30 , wherein, after the welding of the two internal pipes ( 70 ,  71 ) of the double-walled plastic pipes ( 2 ,  3 ) and before the method step of axially displacing the induction connection sleeve ( 1 ) in which the induction connection sleeve ( 1 ) in part surrounds the first plastic pipe ( 2 ) and the second plastic pipe ( 3 ), the mutually welded internal pipes ( 70 ,  71 ) are subjected to a pressure test.