Abstract:
A press jaw pair for producing a press fit of fittings on pipes and the like has a first and a second one-piece press jaw lever ( 1, 2 ) that are arranged such that they are rotatable about a common axis (x). At least one bearing lug ( 4, 8 ) with a bearing opening ( 5, 9 ) is integrally formed on each press jaw lever ( 1, 2 ), wherein the bearing lugs ( 4, 8 ) are arranged coaxially in the fitting state. A torsion spring element ( 3 ) with two stop cams ( 10, 11 ) can be inserted into the bearing openings ( 5, 9 ) in such a way that the two press jaw levers ( 1, 2 ) are supported about the common axis (x) in a spring-loaded fashion and held in a mutually captive fashion.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention pertains to a press jaw pair for pressing units, for example, for producing a press fit of fittings on pipes and the like. 
         [0002]    The invention specifically pertains to such a press jaw pair with two one-piece press jaw levers that are arranged such that they are rotatable about a common axis (x), wherein at least one bearing lug with a bearing opening is integrally formed on each press jaw lever, and wherein the bearing lugs are arranged coaxially in the fitting state. 
       BACKGROUND OF THE INVENTION 
       [0003]    A press jaw pair of this type for hydraulic or electric pressing units is known, for example, from DE-10 2005 028 083. In this solution, each press jaw lever features two integral bearing lugs with coaxial bearing openings, wherein the bearing lugs engage into one another in the fitting state. In the fitting state, a sleeve extends through the coaxial bearing openings of the press jaw levers. The sleeve is secured with Seeger circlip rings on both sides in order to prevent the press jaw levers from axially shifting relative to one another. A tension spring is arranged between the press jaw levers on the force application side in order to hold the press jaw opening open when the pressing unit is not actuated. In this respect, such a press jaw pair forms a subassembly that can be assembled separately. Consequently, a subassembly in the form of a thusly assembled press jaw pair can then be fixed between the fork limbs of a receiving collar of the pressing unit by means of a bolt inserted through the sleeve. 
         [0004]    One disadvantage of the above-described solution according to DE-10 2005 028 083 is that a total of at least 6 individual parts including the tension spring are required for a completely assembled press jaw pair. Another disadvantage can be seen in that asymmetric distributions of forces occur during use due to the uniformity of the press jaw levers (that, however, allows a more rational manufacture) and the interengagement of the bearing lugs. This means that the pressing forces that act against a common center are slightly shifted laterally, wherein this leads to disturbing and uncompensated torques and therefore undesirable shearing forces. 
       SUMMARY OF THE INVENTION 
       [0005]    It is the primary objective of the invention to disclose an improved solution that requires fewer components and therefore also allows a simpler and faster assembly of the press jaw pair. The invention furthermore aims to disclose a solution, in which undesirable shearing forces are also prevented. 
         [0006]    According to the inventive solution, a torsion spring element with two stop cams can be inserted into the bearing lugs in such a way that the two press jaw levers are supported about the common axis (x) in a spring-loaded fashion and held in a mutually captive fashion. 
         [0007]    It should be possible for the press jaw opening of the pressing unit to close automatically when the pressing unit is not in use. For this purpose, stop cams of the torsion spring element are accordingly arranged in assembly recesses in the bearing lugs and the restoring forces of the torsion spring element cause the press jaw opening to automatically close in the desired fashion. All in all, the torsion spring element not only ensures the spring-loaded support, but also captively holds the press jaw levers together. 
         [0008]    The main advantage naturally can be seen in that fewer components are required, namely only a total of 3 including the spring element. It goes without saying that this also simplifies the assembly, wherein a slight overall weight reduction is furthermore achieved. 
         [0009]    In one preferred embodiment, a first bearing lug with a first bearing opening is integrally formed on a first press jaw lever while a pair of bearing lugs with a pair of bearing openings is integrally formed on a second press jaw lever, namely such that the first bearing lug engages into the pair of bearing lugs. Due to this measure, no asymmetric distributions of forces and therefore also no shearing forces any longer occur during use. The occurring forces are compensated by the axially symmetric design. 
         [0010]    In a preferred embodiment, the torsion spring element is furthermore realized in such a way that it extends through the first bearing lug of the first press jaw lever and only one of the two bearing lugs of the pair of bearing lugs. In such a design, neither the spring-loaded support of the press jaw levers nor the cohesion of the press jaw levers is impaired. All in all, this even results in a slight additional weight reduction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    One preferred embodiment of the invention is described in greater detail below with reference to the drawings. In these drawings: 
           [0012]      FIG. 1   a  shows the components of an inventive press jaw pair in the form of a three-dimensional front view, 
           [0013]      FIG. 1   b  shows the press jaw pair according to  FIG. 1  in the form of a three-dimensional rear view, 
           [0014]      FIGS. 2   a, b  show a side view and a top view of the assembled and closed press jaw pair according to  FIG. 1 , and 
           [0015]      FIGS. 3   a, b  show a side view and a top view of the assembled and opened press jaw pair according to  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIGS. 1   a  and  1   b  show the components of an inventive press jaw pair in the form of three-dimensional front and rear views. The press jaw pair essentially consists of a first press jaw lever  1 , a second press jaw lever  2  and a torsion spring element  3 . 
         [0017]    The first press jaw lever  1  is realized in one piece and has a first bearing lug  4  with a first bearing opening  5  in the shape of a circular cylinder, as well as a press jaw shape  6   a  on a working end of the press jaw lever and a cam track shape  7   a  on a force application end of the press jaw lever. 
         [0018]    The second press jaw lever  2  is also realized one piece and has a shape that is similar, but not identical to that of the first press jaw lever  1 , wherein this second press jaw lever features a pair of bearing lugs  8  with a pair of bearing openings  9  in the shape of a circular cylinder. However, a press jaw shape  6   b  on a working end of the press jaw lever and a cam track shape  7   b  on a force application end of the press jaw lever are realized identical to the first press jaw lever  1 . The second press jaw lever  2  furthermore features a pair of opening stops  16  that limit the jaw opening and protect the torsion spring element  3  against an excessive torque. 
         [0019]    The torsion spring element  3  has an outside diameter that fits into the bearing opening  5  in the shape of a circular cylinder of the first press jaw lever  1  and into the pair of bearing openings  9  in the shape of a circular cylinder of the second press jaw lever  2 . The torsion spring element  3  furthermore features a first stop cam  10  and a second stop cam  11 . The torsion spring element  3  serves for ensuring that the two press jaw levers  1 ,  2  are supported in a spring-loaded fashion and captively held together after it is inserted into the bearing opening  5  and the pair of bearing openings  9 . In the assembled state, the press jaw levers  1 ,  2  therefore are arranged such that they are rotatable about a common axis (x) (in this context, see also  FIGS. 2 and 3 ). 
         [0020]    The first bearing opening  5  of the first bearing lug  4  of the first press jaw lever  1  features a first assembly recess  12 , into which the first stop cam  10  of the torsion spring element  3  protrudes in the assembled state. The first assembly recess  12  also has a latching position  15   a  (in this context, see  FIG. 1   b ). 
         [0021]    One bearing opening of the pair of bearing openings  9  of the second press jaw lever  2  features a second assembly recess  13 , into which the second stop cam  11  of the torsion spring element  3  protrudes in the assembled state. The second assembly recess  13  also has an inserting region  14  and a latching position  15   b . The assembly recesses  12 ,  13  with the inserting region  14  and the latching positions  15   a ,  15   b  serve for realizing and for simplifying the insertion of the torsion spring element  3  and the assembly of the press jaw pair. Other details regarding the assembly are provided further below. 
         [0022]    Torsion spring elements of the type shown have the property of generating a resilient restoring force when they are subjected to torsional stress. In this case, the restoring force is used in such a way that the press jaw levers  1 ,  2  close automatically when they are not in use. 
         [0023]      FIGS. 2   a, b  show a side view and a top view of the assembled and closed press jaw pair according to  FIG. 1 . In order to further elucidate the invention, this figure also shows the common axis (x), about which the press jaw levers  1 ,  2  are rotatably arranged. This figure also clearly shows the second assembly recess  13  of the second press jaw lever  2  with the inserting region  14  and the latching position  15   b .  FIG. 2   a  furthermore clearly shows that the torsion spring element  3  extends through the first bearing opening  5  of the first press jaw lever  1  and through only one bearing opening of the pair of bearing openings  9  of the second press jaw lever  2 . 
         [0024]      FIGS. 3   a, b  once again show a side view and a top view of the assembled and opened press jaw pair according to  FIG. 1 . In order to further elucidate the invention, the position of the first assembly opening  12  is also illustrated with broken lines in this figure. In this position, the torsion spring element  3  is maximally tensioned and consequently generates the highest restoring force. The pair of opening stops  16  is illustrated in its end position in this figure, i.e., the press jaw levers  1 ,  2  cannot be opened further and the torsion spring element  3  with its stop cams  10 ,  11  cannot be subjected to an excessive torque. It is assumed that the function of the pressing unit is known analogous to the cited state of the art. It should merely be noted that (not-shown) rolling bodies roll on the cam track shapes  7   a ,  7   b  and are pressed in the direction of the force (F) in such a way that the press jaw levers  1 ,  2  inevitably close (in this context, see  FIG. 2   b ). In contrast to the initially cited state of the art, however, the spring element is used in such a way in this case that the press jaw levers  1 ,  2  can close automatically in the above-described fashion. 
         [0025]    The assembly of the press jaw pair is very simple. It is merely required to assemble three components, namely the press jaw levers  1 ,  2  and the torsion spring element  3 . For this purpose, the press jaw levers  1 ,  2  are assembled as shown in  FIG. 2   a , i.e., in the closed state. The torsion spring element  3  is then inserted into the bearing lug openings  5 ,  9 , wherein this can be easily realized because the assembly recesses  12  and  13  make it possible to insert the protruding stop cams  10  and  11 . The torsion spring element  3  is tensioned and thusly transferred into the assembly position by turning the stop cam in the counterclockwise direction (in this context, see  FIG. 2   b ). The stop cam  10  of the torsion spring element  3  is initially engaged in the latching position  15   a  of the first assembly recess  12  while the stop cam  11  of the torsion spring element  3  is still situated in the inserting region  14  of the second assembly recess  13 . The torsion spring element  3  is ultimately tensioned with its stop cam  11  until the latter engages in the latching position  15   b  of the second assembly recess  13 . 
         [0026]    A person skilled in the art will recognize that the principle with the torsion spring element that is simultaneously used for captively holding together and for supporting the press jaw levers in a spring-loaded fashion can also be readily applied to shapes of press jaw levers, in which each press jaw lever respectively has only one bearing lug or an identical number of bearing lugs. It is therefore also suitable for embodiments, in which press jaw levers with identical shapes are used for reasons of a rational parts manufacture. 
       LIST OF REFERENCE SYMBOLS 
       [0000]    
       
           1  First press jaw lever 
           2  Second press jaw lever 
           3  The torsion spring element 
           4  First bearing lug 
           5  First bearing opening 
           6   a, b  Press jaw shape 
           7   a, b  Cam track shape 
           8  Pair of bearing lugs 
           9  Pair of bearing openings 
           10  First stop cam 
           11  Second stop cam 
           12  First assembly recess 
           13  Second assembly recess 
           14  Inserting region 
           15  Latching positions 
           16  Pair of opening stops 
         (X) Common axis 
         (F) Force direction