Assembly for closing a tube by screwing a cap onto a neck, comprising means for centering the cap

Abstract

An assembly for closing a tube a neck extending along a main axis to a free upper end edge, and comprising a helical external thread, a cap comprising an internal thread complementary to the external thread to allow the cap to be screwed onto the neck, and means for centering the cap with respect to the neck while it is being screwed on, formed by at least one projection which extends from the root of the thread of one of the external thread or the internal thread, a residual radial clearance remaining between the cap and the neck at the level of the projections in the screwed position of the cap on the neck.

1 . An assembly for closing a tube, said assembly comprising:
 a tube head comprising a neck extending along a main axis to a free upper end edge, and comprising a helical external thread, the external thread having a thread root and a thread crest;   a cap comprising an internal thread complementary to the external thread to allow the cap to be screwed onto the neck, the internal thread having a thread root and a thread crest; and   means for centering the cap relative to the neck while it is being screwed on, formed by at least one projection which extends from the thread root of one of the external thread or the internal thread and the height of which is less than that of said thread, a residual radial clearance remaining between the cap and the neck at the level of the projections in the screwed position of the cap on the neck.   
     
     
         2 . The assembly according to  claim 1 , wherein the external thread or the internal thread comprises a plurality of projections which are evenly distributed around the main axis. 
     
     
         3 . The assembly according to  claim 2 , wherein there are four projections. 
     
     
         4 . The assembly according to  claim 1 , wherein each projection is arranged on the external thread of the neck. 
     
     
         5 . The assembly according to  claim 1 , wherein the cap and the neck are made of a rigid plastic material, such as HDPE. 
     
     
         6 . The assembly according to  claim 1 , wherein each projection has the same rigidity as the thread crest of the other of the external thread or the internal thread. 
     
     
         7 . The assembly according to  claim 1 , wherein each projection is in the form of a rib which axially connects two adjacent turns of the thread. 
     
     
         8 . The assembly according to  claim 1 , wherein at least one of the projections is arranged between the two upper end turns of the thread. 
     
     
         9 . The assembly according to  claim 1 , further comprising a foil seal closing said neck, the foil seal having a radial gripping tab folded down against the external thread of the neck, the radial tab being received in a nominal radial clearance between the upper end turn of the internal thread and the neck. 
     
     
         10 . The assembly according to  claim 1 , wherein the width of the projection, taken in the orientation of the turn, is less than its height. 
     
     
         11 . The assembly according to  claim 1 , wherein the upper end turn of the internal thread has a decreasing height from bottom to top so that the nominal radial clearance between the thread crest of said end turn and the thread root of the external thread of the cap is greater than the nominal radial clearance between the other turns of the internal thread and the external thread. 
     
     
         12 . The assembly according to  claim 1 , wherein the neck comprises a non-threaded upper end portion, said portion having a frustoconical shape. 
     
     
         13 . A tube comprising a closure assembly according to  claim 1 .