Patent Publication Number: US-2010117352-A1

Title: Connecting arrangement for a pipe union

Description:
The invention relates to a connecting arrangement for connecting a cylindrical pipe or pipe section to a connecting body, whereby the connecting body has a first conical bore that proceeds from a face surface, a first cylindrical bore that follows the conical bore, to accommodate the pipe, and a second cylindrical bore that follows the first cylindrical bore and is reduced in diameter, with a union nut that has a bore for the pipe or pipe section, with a thread with which the union nut can be screwed onto a counter-thread of the connecting body, and with a conical bore that narrows opposite to the conical bore of the connecting body, with a cutting ring that has a first cone, which sits in the conical bore of the union nut, which cutting ring has a bore for passing the pipe or pipe section through and at least one radially circumferential blade, which face the pipe or pipe section, and with an intermediate ring that has a bore for the pipe or pipe section, which ring is disposed between the cutting ring and the connecting body, and which intermediate ring has a conical bore that presses against a second cone of the cutting ring. 
     Pipe unions are supposed to become possible with such connecting arrangements. In this connection, a pipeline, particularly a metallic one, is supposed to be connected to a connecting piece that has an accommodation opening for the pipeline. A union nut that can be screwed together with the connecting piece can be turned while being connected, and thus exerts an axial movement on a cutting ring that is situated between the union nut and the connecting piece. By means of disposing different conical bores and counter-pieces that sit in them, the axial movement is transferred to a cutting ring having a blade, in such a manner that when the union nut is tightened, a deformation radially toward the inside takes place in certain sections. A cutting edge then cuts into the material of the pipeline, with shape fit and with a notch effect. 
     Such concepts are known, for example, from DE 196 37 129 C2 or EP 0 863 354 B1. These and other concepts are also used in practice in many ways. 
     It is problematic that because of the plurality of the small elements that can move relative to one another, which all surround the pipe to be connected in ring shape, a relatively great amount of force must be exerted to assure the different deflection movements. 
     In contrast with this, it is the task of the invention to propose a connecting arrangement for pipe unions that can be screwed together with little expenditure of force, without any loss in reliability and functionality for the user. 
     This task is accomplished, in the case of a connecting arrangement of the stated type, in that the cutting ring is slit parallel to the axis of the pipe. 
     The task is surprisingly accomplished in this way. The cutting ring does not lose any of its functionality as the result of the slit. It continues to possess a circumferential blade that can cut into the outer surface of the pipe, with a notch effect. The slit does not change this. However, the cutting ring becomes significantly more easily deformable in the radial direction. It offers practically no resistance to corresponding forces and movements any longer. This means that clearly reduced forces occur for the user during assembly of the connecting arrangement, in other words when screwing the union nut onto the thread of the connecting body. 
     In order to implement this effect of the slit cutting ring particularly well, specific values for the different angles have proven to be particularly practicable. 
     Thus, it is preferred if the cone angle of the second cone of the cutting ring and the cone angle of the conical bore of the intermediate ring amount to more than 20°, in each instance, particularly about 30° (±)5°. 
     In particular, much more precise radial cutting furthermore becomes possible in this way. Conversion of the axial forces when screwing the union nut on into radial forces for allowing the cutting blades to cut into the outer surface of the pipe takes place in significantly more precise manner. 
     Conventionally, the cone angle of the second cone of the cutting ring has usually been set at about 12°. However, because of the preferred characteristics, a cone angle in a range around 30° occurs in the new cutting ring. This means that at the same axial paths during joining of the connecting arrangement according to the invention, the cutting ring now cuts clearly deeper, and thus a significantly more reliable connection is formed. According to deliberations, the connection should now be better by a factor of about 2.8 than the one from the state of the art. 
     In a closer consideration with numerical examples, 1 mm axial path, for example, corresponds to a distance of 0.21 mm radial path at a conventional cone angle of 12°, while in the case of a configuration of the cone angle according to the invention, at 30°, the 1 mm axial path becomes a radial path of 0.57 mm. 
     One can think of this as meaning that the new concept according to the invention leads to the result that the cutting ring is clearly deformed more in the radial direction because of the steeper angle than in the case of the conventional designs with their flatter cone angles on the cutting rings. Thus, the cutting ring now cuts into the pipe material better, according to the invention. 
     Because significantly more precise and reliable radial cutting of the cutting ring now takes place, tolerances of the cutting ring are also balanced out better. The diameter tolerance of the cutting ring, for example, becomes significantly more tolerant of errors, so that the overall effect becomes even more reliable. 
     Because the cutting ring also clearly cuts better radially, not only the diameter tolerance but also the blade rounding become clearly more tolerant of errors and more reliable. 
     Likewise, it is preferred if the intermediate ring has a contact limitation surface, the cutting ring has a support surface that corresponds to the contact limitation surface, on the side adjacent to the intermediate ring, and the contact limitation surface and the conical bore of the intermediate ring enclose an angle with one another. 
     The concept also has other advantages. This is because the special arrangement of the intermediate ring makes it possible to separate the function of cutting and holding from a function of sealing that is also preferably desired. 
     This preferably takes place in that the intermediate ring has a soft sealing element that is disposed between the wall of the pipe, the intermediate ring, and the conical bore of the connecting body, surrounding the pipe. 
     This holds true particularly preferably if the soft sealing element is separated from the cutting ring by means of the intermediate ring that lies against the pipe on the outside. 
     It is furthermore particularly preferred if the dimensions of the cutting ring and of the intermediate ring are dimensioned to be so great that after assembly is complete, the cutting ring lies on the contact limitation surface of the intermediate ring with its support surface (and on the outside of the pipe with the surface that carries the blades. 
     This specifically allows clear signaling of the end of assembly, namely when the cutting ring lies on the intermediate ring. In this manner, over-assembly of the cutting ring can be precluded. 
     In total, the axial path of the union nut and of the cutting ring is now optimally converted to a radial path, according to the invention. Cutting by the cutting ring is clearly improved. This is supported with optimized angles. 
     It is furthermore preferred if blade rounding is provided. With blade rounding, the risk of the pipe tearing out is reduced, in other words the risk of unintentional loosening of the connecting arrangement due to the exertion of great forces. After all, it must be considered that when such events occur, the entire forces have to be absorbed by the blade. 
    
    
     
       An exemplary embodiment of the invention will be explained in greater detail in the following, using the drawing. This shows: 
         FIG. 1  a section through an embodiment of a connecting arrangement according to the invention; 
         FIG. 2  an enlarged representation of a detail from  FIG. 1 ; 
         FIG. 3  a top view of a cutting ring according to the invention; and 
         FIG. 4  a perspective representation of the cutting ring from  FIG. 3 . 
     
    
    
     A pipe union of a pipe  10  with a connecting body  20  is explained in greater detail in  FIG. 1 . The pipe  10  is cylindrical; in  FIG. 1 , a bottom end of the pipe  10 , which can be significantly longer and could also be part of a pipeline arrangement, is shown as an example. 
     This pipe  10  is inserted into a connecting body  20 . For this purpose, the connecting body  20  possesses a first cylindrical bore  21 , which is precisely dimensioned so that the pipe  10  can be inserted there. A second bore  22  is provided with a smaller diameter. This second bore  22  continues the first bore in the direction of the interior of the connecting body  20 . A medium situated in the interior of the pipe  10  can thus get into the second bore  22  and be conveyed further there. 
     In this connection, the pipe  10  supports itself on a face surface  25 , which separates the first bore  21  and the second bore  22  from one another. 
     Another face surface  24  is provided as the outer surface of the connecting body  20 ; in this connection, the first, outer cylindrical bore  21  makes a transition into a conical bore  23  that opens in the direction of the face surface  24 . 
     On the outside the connecting body  20  also has a thread  28 , which is equipped for forming a screw connection with a counter-thread  38  that will still be described further in the following. 
     Specifically, a union nut  30  having the counter-thread  38  can be screwed onto the thread  28  of the connecting body  20 . The union nut  30  possesses a bore  31  through which the pipe  10  can be guided. Between the bore  31  and the thread  38 , another section is provided, in which the bore through the union nut  30  widens in the direction toward the connecting body  20 , as a conical bore  33 . 
     Between the connecting body  20  and the union nut  30 , there is a cutting ring  40 . This cutting ring  40 , in the embodiment shown, possesses two circumferential blades  41  and  42 , which are directed in the direction of the outer surface of the pipe  10 , in each instance. The cutting ring  40  surrounds the pipe  10 , which projects through a bore  46  of the cutting ring. 
     The cutting ring  40  furthermore possesses a first cone  43 , which is directed against the union nut  30  and sits in the conical bore  33  of the union nut  30  during assembly. 
     The cutting ring  40  furthermore possesses a second cone  44 , which narrows in the direction opposite to the first cone  43 . 
     An intermediate ring  50  is disposed between the cutting ring  40  and the connecting body  20 . This intermediate ring  50  also possesses a bore  51  for the pipe  10  and surrounds this pipe  10 . The intermediate ring  50  can also be referred to as an adapter element or as a holding ring. 
     This intermediate ring  50  possesses a circumferential support surface  52  with which it lies on the face surface  24  of the connecting body  20 . 
     Furthermore, it possesses a conical bore  53  on the side facing away from this support surface  52 . The second cone  44  of the cutting ring  40  sits in this conical bore  53 . 
     This conical bore  53  borders on and makes a transition into a contact limitation surface  54  of the intermediate ring  50 , adjacent to the bore  51  of the intermediate ring  50 . 
     Opposite this contact limitation surface  54  lies a support surface  45  of the cutting ring  40 , which at first still has a distance from this contact limitation surface. 
     The intermediate ring  50  furthermore carries a soft sealing element  60 . This soft sealing element  60  is situated between the outer wall of the pipe  10 , the conical bore  23  of the connecting body  20 , and a corresponding carrying device of the intermediate ring  50 . Since the intermediate ring  50  also borders on the outer wall of the pipe  10 , the soft sealing element  60 , which also runs around the pipe  10 , is permanently mechanically separated from the cutting ring  40 . 
     The enlarged representation of Detail B in  FIG. 2  shows, in particular, what angles the conical bores have and what the approximate size ratios of the individual elements relative to one another are. 
     Again, the wall of the pipe  10 , the consecutive regions of the connecting body  20 , of the intermediate ring  50  with the soft sealing element  60 , of the cutting ring  40 , and furthermore of the union nut  30  can be clearly seen. 
     The cutting ring  40  can be seen particularly well in  FIG. 3 , in a top view. One can see here that it is not a continuous, closed ring that surrounds the bore  46 , but rather that it has a slit  47 . As a result, it is significantly more easily deformable radially, even when it is laid around the pipe  10 . 
     Perspectively, one can see in  FIG. 4  what the structure of the slit  47  is and how it behaves relative to the cone-shaped regions. 
     During assembly of a pipe  10  to the connecting body  20 , the union nut  30 , with the cutting ring  40  and the intermediate ring  50  situated on it, is pushed into the pipe from below, this pipe is then inserted into the connecting body  20 , and afterwards, screwed on by way of the union nut  30 . 
     The rings situated in it assume their position on their own, since the conical bores  23 ,  33 , and  53  precisely match the cone-shaped elements  43  and  44 . 
     By means of screwing the union nut  30  on, the small gap that at first exists between the support surface  45  on the cutting ring  40  and the contact limitation surface  54  on the intermediate ring  50  is closed, but at the same time, over-assembly of the cutting ring  40  is thereby prevented. 
     REFERENCE SYMBOL LIST 
       10  pipe (cylindrical) 
       20  connecting body 
       21  bore (first cylindrical bore for the pipe  10 ) 
       22  bore (second, having a smaller diameter) 
       23  conical bore 
       24  face surface, against the intermediate ring 
       25  face surface, against the pipe  10   
       28  thread for screw connection with union nut  30   
       30  union nut 
       31  bore for the pipe  10   
       33  conical bore 
       38  thread for a screw connection with connecting body  20   
       40  cutting ring 
       41  first blade (circumferential) 
       42  second blade (circumferential) 
       43  first cone against union nut  30   
       44  second cone against intermediate ring  50   
       45  support surface against intermediate ring  50   
       46  bore for the pipe  10   
       47  slit 
       50  intermediate ring 
       51  bore for pipe  10   
       52  support surface against connecting body  20   
       53  cone for cutting ring  40   
       54  contact limitation surface for cutting ring  40   
       60  soft sealing element