Patent Abstract:
A joint assembly for flexible and semi-rigid piping, such as high density polyethylene piping or the like. The assembly comprises a joint end sleeve and a nut. The joint end sleeve comprises in series first, second, third and fourth co-axial sections of circular cross-sections. The first and second sections are to be disposed within the end of the piping. The nut, with an internal threaded surface, is made of a material harder than the one used in the piping and with a higher or equal hardness than the one on the joint end sleeve. The nut is configured to press the end of the piping around the first and second sections

Full Description:
FIELD OF THE INVENTION 
     The present invention is related to a joint assembly for flexible and semi-rigid pipings, such as high-density polyethylene pipings or the like, wherein the system comprises a special nut and a joint end sleeve. 
     BACKGROUND OF THE INVENTION 
     The U.S. Pat. No. 5,178,423 of A. Combeau consists of a fast assembly for flexible pipings which, unlike the present invention, a butt does not take place between the nut ( 6 ) and the threaded element ( 5 ) of the patent, in such a way that the nut risks to be subjected to hazardous tensions if it is excessively tightened by the installer. Also, the lack of a butt on the nut may result in a variable tightening of the piping, which is subject at the installer&#39;s discretion and care, with the resulting risks of leakage in the event that the tightening gets loosened or taking the risk that nut be damaged as a consequence of an excessive tightening. On the contrary, the joint of the present invention has butting means for axial displacement, so that the nut cannot be tightened against the piping beyond a displacement predetermined by manufacturer. 
     The U.S. Pat. No. 5,860,678 of M. Mittersteiner (the same inventor who is one of the co-inventors of the present invention) shows a self-threading joining. Unlike the present invention, in the patent 678′ , it is not possible to get a joining in a quick way, because the nut threads must be continuous and extend themselves by more than one turn to be able to form the thread in the piping. On the contrary, in most of the embodiments of the present invention, the nut can have a discontinuous threading that is threaded with the joint end sleeve, with the purpose of achieving a full tightening in a fraction of a turn. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To understand the invention better, it will be described on the basis of two preferred embodiments which are shown in the following figures, wherein: 
         FIG. 1   a  shows a cross section view of the assembly for a first embodiment of the invention, in an initial situation of the piping installation in it; 
         FIG. 1   b  shows the same first embodiment of  FIG. 1   a , with the piping already installed in it; 
         FIG. 2   a  shows a cross section view of the assembly for a second embodiment of the invention, in an initial situation of the piping installation in it; 
         FIG. 2   b  shows the same second embodiment of  FIG. 2   a , with the piping already installed in it; 
         FIG. 3   a  shows a cross section view of the assembly for a third embodiment of the invention, in an initial situation of the piping installation in it; 
         FIG. 3   b  shows the same third embodiment of  FIG. 3   a , with the piping already installed in it; 
         FIG. 4   a  shows a cross section view of the assembly for a fourth embodiment of the invention in an initial situation of the piping installation in it; and 
         FIG. 4   b  shows the same fourth embodiment of  FIG. 4   a , with the piping already installed in it. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 1   a  and  FIG. 1   b , according to a first embodiment, the invention&#39;s joint end assembly comprises a joint end sleeve  110  and a special nut  130 , made of a material harder than the material used in the piping  120 , which aims to join said joint end sleeve  110 , and with a hardness higher or equal to the last one. 
     The joint end sleeve  110  consists of four co-axial sections with circular cross sections, all of which are affected by a passing duct  111 . A first section of the joint end sleeve  110  consists of a truncated-cone shaped end  112 , being its narrower end external, whose outside diameter on said end is slightly smaller than the inside diameter of the piping  120 . A first smooth cylindrical section  114  follows to the base with the biggest diameter at the conical end  112 , with an outside diameter smaller than the outside diameter of said larger base of the conical end  112 , being of a diameter preferably substantially equal to the outside diameter of the smaller end of said conical section  112 . The first cylindrical section  114  is succeeded by a threaded cylindrical section  116 , with such a diameter that the respective nut  130  allows to pass through the piping  120  in a way smoothly tightened. The other end of the joint end sleeve  110  finishes in a second smooth section  118 , cylindrical, with a diameter that will depend on the application of the joint. A throat  113  is formed between the large diameter edge of the truncated-cone shaped section  112  and the top edge of the first cylindrical section  114 . 
     The special nut  130  of the joint end assembly has two types of co-axial surfaces on its hollow: a smooth cylindrical top surface  131 , larger and with a bigger diameter, preferably slightly larger than outside diameter of the piping  120 ; and a threaded cylindrical surface  134  with a smaller average diameter and an average diameter slightly larger than average diameter of the smooth cylindrical surface  131 , being this thread supplementary to the thread of the threaded cylindrical section  116  of the joint end sleeve  110 . These threads can be made up of a continuous (or standard) thread or of a segmented (or discontinued) thread as of a quick fastening type. 
     To carry out the joint between the piping  120  and the joint end assembly of the invention, the special nut  130  is inserted into the end of the flexible or semi-rigid piping  120 , in such a way that the threaded surface  134  is oriented to the end of said piping. Then the flexible or semi-rigid piping end  120  is axially inserted by external end of truncated-cone shaped section  112  of joint end sleeve  110 , until the end of said piping  120  contacts the annular top face of threaded cylindrical section  116  of said joint end sleeve  110 . In this operation, the piping will be (elastically or plastically) deformed (depending on the manufacturing material) when the piping is inserted into the truncated-cone shaped section  112  and the flexible or semi-rigid piping end  120  will tend to contract itself to fit into the throat  113  of the first cylindrical section  114 . Finally, the special nut  130  is axially slid in direction to the threaded cylindrical section  116  of said joint end sleeve  110  in order to thread it to this, until the annular cross-section surface of the nut, which is formed between the top area of the of threaded cylindrical surface  134  and the bottom area of the smooth cylindrical surface  131 , contacts the annular top surface of threaded cylindrical section  116  of the joining end  110 . 
     By starting the threading, the smooth surface  131  of the special nut  130  does not still exercise any radial pressure on the external face of the piping  120 , because this smooth surface  131  is found over the widening produced on the piping by the truncated-cone shaped area of the joint end sleeve  110 . As the threading of the special nut  130  moves axially forward into the threading of said sleeve  110 , the smooth cylindrical surface  131  of said nut  130  starts to compress in radial direction to the piping  120 , which suffers elastic and plastic deformation, and compresses itself against the surface of the joint end sleeve  110  and filling the space of its throat  113 , so that the piping is firmly caught by radial compression between said sleeve  110  and said special nut  130 . 
     A second embodiment of the invention is shown in  FIGS. 2   a  and  2   b , wherein the joint end assembly of the invention comprises a joint end sleeve  210  and a nut  230 , made of a material harder than the one used in piping  220 , which is intended to be joined to said joint end sleeve  210 , and with a hardness equal or higher than the last one. 
     The joint end sleeve  210  consists of four co-axial sections with circular section, all of which are affected by a passing duct  211 . A first section of the joint end sleeve  210  consists of a truncated-cone shaped end  212 , being its narrower end external and whose outside diameter in said end is slightly smaller than the inner diameter of the piping  220 . The larger diameter base of the truncated-cone shaped end  212  is succeeded by a first smooth cylindrical section  214 , with an outside diameter smaller- than the outside diameter of said larger base of the truncated-cone shaped end  212 , being a diameter rather substantially equal to the outside diameter of the smaller end of said truncated-cone section  212 . The first cylindrical section  214  is succeeded by an intermediate-smooth cylindrical section  217  whose diameter is larger than the inside diameter of the nut  230 . The other end of the joint end sleeve  210  ends in a second smooth section  218 , preferably cylindrical, with a diameter which will depend on the joint application. A throat  213  is formed between the larger diameter edge of the truncated-cone section  212  and the top edge of the first cylindrical section  214 . 
     The nut  230  of the joint end assembly has an internal threaded surface  234 , which extends itself axially on the end, being the smaller diameter of the larger threading, preferably slightly larger than the diameter of the piping  220 . 
     To carry out the union between piping  220  and joint end assembly of the invention, the nut  230  is inserted into an end of flexible or semi-rigid piping  220 . Then, the end of flexible or semi-rigid piping  220  is axially inserted by the external end of the truncated-cone section  212  of the joint end sleeve  210  until the end of the piping  220  contacts the annular top face of the intermediate cylindrical section  217  of the joint end sleeve  210 . The piping will be elastically and/or plastically deformed in this operation when the piping is inserted into a truncated-cone shaped section  212  and the flexible or semi-rigid piping end  220  will tend to contract itself to fit into the throat  213  of the first cylindrical section  214 . Finally, the nut  230  is axially slid and rotated in direction to the intermediate cylindrical section  217  of said joint end sleeve  210 . 
     By starting both the turn and axial displacement of the nut  230 , the threaded surface  234  of said nut  230  does not exert any radial pressure on the external face of the piping  220  yet, because said surface  234  is over the widening produced on the piping by the truncated-cone area of the joint end sleeve  210 . When the nut achieves the mentioned widening on the piping  220 , the threaded nut  234  of said nut  230  starts to thread itself on the piping  220  by compressing itself radially; and it is elastically and plastically deformed to be compressed against the surface of the joint end sleeve  210  by filling space of the throat  213  of the sleeve  210  so that piping  220  is firmly caught between the sleeve  210  and the nut  230  by compression. 
       FIGS. 3   a  and  3   b  show a third embodiment of this invention, wherein the joint end assembly comprises a joint end sleeve  310 , a flexible tightening ring  340  and a nut  330  made of a material harder than the material used for the piping  320  which is intended to join to said joint end sleeve  310 , being said nut  330  with a larger or same hardness than said joint sleeve  310 . 
     The joint end sleeve  310  is made up by three co-axial sections, with a circular section, which are affected by a passing duct  311 . A first section  314  of the joint end sleeve  310  is cylindrical with an outside diameter slightly smaller than the inside diameter of the piping  320 , having at least one annular groove  319  in its cylindrical mantle. The first cylindrical section  314  is succeeded by a threaded cylindrical section  316 , with a diameter slightly larger than the outside diameter of the piping  320 , so that it presents a top annular stop surface for said flexible ring  340  and for the nut  330 . The other end of the joint end sleeve  310  ends in a third smooth cylindrical section  318 , with a cross-section which will depend on the joint application. 
     The flexible tightening ring  340  has a truncate-cone shape and its inside mantle has at least one annular edge  349  which will be cooperative with said at least one groove  319  of said cylindrical section  314  of the joint end  310 , so that the inside diameter of the annular edge  349  should be substantially equal to the outside diameter of the piping  320 . Optionally, the flexible tightening ring  340  can have one or more longitudinal grooves  315   a , made up by its perimetric wall. Preferably, the flexible tightening ring  340  has a longitudinal discontinuation  315 , so that the body of the ring  340  results perimetrically discontinuous. 
     The nut  330  of the joint end assembly has three types of internal co-axial surfaces. A first internal surface  331  is extreme and consists of a cylindrical slot, with a diameter slightly larger than the outside diameter of the piping, so that this passes through smoothly. The first internal surface  331  is axially succeeded by an intermediate surface with a truncated-cone shaped mantle  336 , with the smaller diameter end next to the mentioned first cylindrical surface  331 , being this smaller diameter larger than the diameter of the surface  331  but smaller than the larger outside diameter of the flexible tightening ring  340 . The larger diameter of said intermediate surface with a truncated-cone shaped mantle  336  is slightly larger than the smaller diameter of the external truncated-cone shaped surface of said flexible tightening ring  340 , wherein the conicities of both truncated-cone shaped surfaces are identical, in order to produce a radial tightening force component larger than the axial tightening force component when this nut  330  advances. A third internal surface  334  is threaded and supplementary to the second cylindrical threaded section  316  of the joint end sleeve  310 . 
     To carry out the joint between the piping  320  and the joint end assembly of the invention in this third embodiment, the nut  330  is inserted into the piping end  320 , with a threaded end oriented to the end of the mentioned piping  320 . Then, the flexible tightening ring  340  is axially inserted into the piping  320 , with its larger diameter end oriented to the end of the mentioned piping  320  in order to insert the piping end  320  through the external end of the first cylindrical section  314  on the joint end sleeve  310 , until the end of the piping  320  contacts the annular top surface of the second cylindrical threaded section  316  of the mentioned joint end sleeve  310 . Then, it is axially slid and by turning the nut  330  in direction to the second cylindrical threaded section  316  of said joint end sleeve  310 , until the top edge of the flexible tightening ring  340  contacts the annular top edge of intermediate surface of the truncated-cone shaped mantle of the nut  330 . 
     At the start of the axial displacement and the turning of the nut  330 , the intermediate surface of the truncated-cone shaped mantle  336  of said nut  330  starts to compress the flexible tightening ring  340 , which in turn compresses the piping  320  in radial direction, with at least one annular edge  349 , so that the mentioned piping  320  is radially deformed by filling the annular groove(s)  319  of said first section  314  on the joint end sleeve  310  so that the piping  320  gets firmly caught among said sleeve  310 , said flexible tightening ring  340  and said nut  330  by radial compression. In case of existing one or more perimetrical grooves  315   a  or a longitudinal discontinuance  315  in said flexible tightening ring  340 , these grooves or this discontinuance will cooperate with the deformation of said ring  340  so that it fits to the piping  320  with less effort. 
     Because of the nature of the third embodiment of the invention, unlike other embodiments of this invention, the joint can be applied in rigid type pipings, besides the flexible and semi-rigid pipings. A rigid piping type on which the third embodiment of the invention can be applied is that one of annealing copper, not being this case restrictive. 
     A fourth embodiment of this invention is shown in  FIG. 4   a  and  FIG. 4   b , wherein the invention joint end assembly comprises a joint end sleeve  410 , a tightening ring  440  and a nut  430 , which is made of a material harder than the one used in the piping  420  intended to connect to this joint end sleeve  410  and with a hardness equal or higher than this one. 
     The joint end sleeve  410  consists of four co-axial sections with circular cross sections, and each of these sections is affected by a passing duct  411 . A first section of the joint end sleeve  410  consists of a truncated-cone shaped end  412 , and its external end is the narrowest end whose outside diameter in that end is slightly smaller than the inside diameter of the piping  420 . The larger diameter base of the truncated-cone shaped end  412  is succeeded by a first smooth cylindrical section  414 , with an outside diameter smaller than the outside diameter of the mentioned larger base of the truncated-cone shaped end  412 , being of a diameter substantially equal to the outside diameter of the smaller end of said truncated-cone shaped section  412 . The first cylindrical section  414  is succeeded by a second threaded cylindrical section  416 , with a diameter slightly larger than outside diameter of the piping  420 , in such a way that it shows a top annular stop surface for the mentioned piping. The other end of the joint end sleeve  410  finishes in a second smooth section  418 , preferably cylindrical, whose diameter will depend on the joint application. A throat  413  is formed between the larger diameter edge of truncated-cone shaped section  412  and the top edge of the first cylindrical section  414 . 
     The tightening ring  440  has an external truncated-cone shaped surface and an internal cylindrical surface, with a diameter slightly larger than the piping diameter  420 . Optionally, the tightening ring  440  can have one or more longitudinal grooves  415   a , on the perimetrical wall. Preferably, the tightening ring  440  has a longitudinal discontinuance  415  so that the body of this ring  440  results perimetrically discontinuous. 
     The nut  430  of the joint end assembly has three types of internal and co-axial surfaces. A first internal surface  431  is terminal and consists of a cylindrical opening with a diameter slightly larger than the outside diameter of the piping, so that this one passes trough smoothly. An intermediate surface of the truncated-cone shaped mantle  436  whose conicity is substantially identical to the conicity of said tightening ring  440 ; being the smaller diameter end close to said cylindrical surface  431 , but smaller than the outside larger diameter end of the tightening ring  440 . The larger diameter of said intermediate surface of truncated-cone shaped mantle  436  is slightly larger than the smaller diameter of the external truncated-cone shaped surface of said tightening ring  440 , wherein the conicities of both truncated-cone shaped surfaces are identical, in order to produce a radial tightening force component larger than the axial tightening force component when this nut  430  advances. A third internal surface  434  of the nut is threaded, which is supplementary to a second cylindrical threaded section  416  of the joint end sleeve  410 . 
     To carry out the joint between the piping  420  and joint end assembly of the invention of this fourth embodiment, the nut  430  is inserted into the piping end  420 , with a threaded end oriented to the end of said piping  420 . Then the tightening ring  440  is axially inserted into said piping  420 , with its larger diameter end oriented to the end of said piping  420 , so that the end of said piping  420  be inserted afterwards by the end of the first cylindrical section  414  on the joint end sleeve  410 , until the end of the piping  420  contacts the annular top surface of the second cylindrical threaded section  416  of said joint and sleeve  410 . Then it is axially slid and the nut  430  is turned in direction to the second cylindrical threaded section  416  of said joint end sleeve  410 , until the top edge of the tightening ring  440  contacts the annular top edge of the intermediate surface of the truncated-cone shaped mantle  436  of the nut  430 . 
     By starting to move axially and turn the nut  430 , the intermediate surface of the truncated-cone shaped mantle  436  of said nut  430  starts to compress the tightening ring  440 , which in turn radially compresses the piping  420 , so that the piping  420  gets radially deformed, filling the throat  413  of the joint end sleeve  410  in such a way that the piping  420  gets firmly caught by radial compression between said sleeve  410 , the tightening ring  440 , and the nut  430 . Additionally, when the nut  430  is almost completely threaded in the threaded cylindrical section  416  of that joint end sleeve  410 , the cylindrical surface  461  compresses also the piping  420  against the throat  413 , thereby increasing the tightening of the joint assembly.

Technology Classification (CPC): 5