Abstract:
The present invention relates to crimping pliers designed and arranged for manually crimping a work piece. Such crimping pliers comprise two manually operated hand levers coupled by a transfer mechanism with two crimping jaws. A closing mechanism is designed and arranged for being operated independent on said hand levers. Upon activation of the closing mechanism the crimping jaws are moved from an open state in a partial movement in a further closed starting state. The crimping jaws are secured in the starting state against returning into said open state. Starting from said starting state the crimping jaws are movable in an additional partial movement towards each other upon manipulation of the hand levers.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to co-pending German Patent Application No. DE 10 2008 005 472.0 entitled “Presszange”, filed Jan. 22, 2008. 
       FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to crimping pliers for manually crimping a work piece, in particular a holder, a contact element, a fitting, conduits or pipes, cable lugs and the like. 
       BACKGROUND OF THE INVENTION 
       [0003]    A plurality of crimping pliers exists with a lot of different embodiments with different transmission mechanisms for the force between the hand levers and the crimping jaws. The design of such crimping pliers depends on the need of producing large crimping forces with limited forces applied by the users upon the hand levers. Furthermore, the crimping pliers should be useable in a comfortable and economic way. 
         [0004]    Crimping pliers for manually crimping a work piece are known from German Patent No. DE 199 63 097 C1 corresponding to U.S. Pat. No. 6,474,130 B2 of the applicant. These crimping pliers comprise two manually activated hand levers. The movement of the hand levers and forces applied upon the hand levers are transferred by a transmission mechanism having a suitable transmission ratio. 
         [0005]    German Patent Application DE 1 275 490 A corresponding to U.S. Pat. No. 3,101,017 A discloses tongs having two hand levers wherein a pivoting movement of the hand levers results in a pivoting movement of a cam disc. The cam disc activates a toggle lever mechanism being linked with the jaws of the tongs. By means of a pawl the movement of the cam disc might be locked at the end of a plurality of crimping steps. 
       OBJECTIVE OF THE INVENTION 
       [0006]    It is an object of the present invention to provide crimping pliers having a new transfer or transmission mechanism for forces applied upon the hand levers to the crimping jaws. 
         [0007]    Furthermore, it is an object of the present invention to provide new crimping pliers with an improved activation of the crimping jaws in different conditions of use. 
       SUMMARY OF THE INVENTION 
       [0008]    According to the present invention, the crimping pliers are not solely activated via the hand levers. The crimping pliers comprise a closing mechanism that might be activated independent on the hand levers in a state of the crimping pliers with the work piece introduced between the crimping jaws. By manual activation of the closing mechanism the crimping jaws are movable from an open state via a partial movement into a further closed starting state. It is possible that in the starting state there is still a small gap between the work piece and the crimping jaws (or a die held by the crimping jaws). However, it is also possible that the manual activation of the closing mechanism closes a gap between the work piece and the crimping jaws that exists in the open state so that in the starting state the crimping jaws contact the work piece. Accordingly, it is possible that the closing mechanism is responsible for a partial movement without any application of crimping forces to the work piece. However, it is also possible that for the movement caused by the closing mechanism first crimping forces are applied upon the work piece. 
         [0009]    The starting state of the crimping jaws builds a stable operating state of the crimping pliers with the work piece located within the crimping jaws. This is due to the fact that in the starting state the crimping jaws are secured against returning into the open state. Accordingly, the crimping jaws and the work piece might build a connection with or without play so that at the end of the closing movement caused by the closing mechanism it is possible to hold the crimping pliers and the work piece only with one or two hands at the crimping pliers. 
         [0010]    Starting from the starting state by means of a movement of the hand levers a further partial movement of the crimping jaws is possible. For the pliers according to the invention, a first partial movement of the crimping jaws is caused by the closing mechanism, whereas a second partial movement of the crimping jaws is caused by the hand levers. 
         [0011]    According to a further embodiment of the invention, the transfer or transmission mechanism between the hand levers and the crimping jaws has a transmission ratio which is larger than the transmission ratio of the closing mechanism for the transfer of the forces applied by the user upon the hand levers. Such design of the different transmission ratios might be used for an efficient performance of the first partial movement without crimping forces or with small crimping forces but small movements of the activating element of the closing mechanism leading to large movements of the crimping jaws for overcoming a gap between the crimping jaws and the work piece. On the other hand, it is possible to design the transfer or transmission mechanism for the second partial movement with the right transmission ratio for the real crimping process or the end phase of the crimping process with increased crimping forces. 
         [0012]    It is also possible that the starting state reached at the end of the activation of the closing mechanism is fixed by a constructive design of the pliers leading to one single defined relative position of the crimping jaws in the starting state. For such an embodiment there is a partial movement between the open state and the starting state with one single predetermined length. However, according to the invention it is also possible that the closing mechanism is used for gaining different starting states, e.g. depending on the dimensions of the work piece. Such different starting states might be predetermined in a plurality of steps such that the amount of the partial movement between the open state and the starting state might be changed in steps depending on the dimensions or the materials of the work piece worked with the crimping pliers. For determining the closing angle or distance of the jaws in the starting state the crimping pliers might have adjusting means. Furthermore, it is possible that there is an automated adaption of the starting state to the dimensions of the work piece located in the crimping pliers. It is also possible that there is a stepless, continuous adaption of the starting state that is reachable via the closing mechanism. According to one embodiment the partial movement towards the starting state is automatically stopped at the instance that the crimping jaws contact the periphery of the work piece or crimping forces applied during the first partial movement exceed a predetermined force level. 
         [0013]    A plurality of different starting states might be provided by the closing mechanism by means of different constructions. According to one embodiment there is an adjustable stop element that is responsible for limiting the starting state. A very simple but efficient way of guaranteeing the starting state is given with the use of a locking-, rest- or ratchet-mechanism (in the following “ratchet-mechanism”) used as a part of the closing mechanism. For such embodiment a plurality of ratchet levels are passed during the partial movement from the open state to the starting state. These ratchet steps guarantee that a position once reached during the closing movement is not left in opening direction. The starting state might be reached for a contact of the crimping jaws with the outer circumference of the work piece. Such position might be secured in opening direction via the ratchet-mechanism. It is also possible that the distance between adjacent ratchet steps of the ratchet-mechanism determines preferred starting states. For such ratchet-mechanism there might be some play between the crimping jaws and the work piece whereas the forces applied by the closing mechanism are not sufficient for reaching the next crimping step in closing direction. 
         [0014]    In the crimping pliers according to the invention any known transfer or transmission mechanism might be used. The inventive concept might be incorporated in crimping pliers independent on the crimping jaws performing a pivoting movement for closing or the crimping jaws being closed in a translational relative movement. 
         [0015]    Another embodiment of the invention focuses on the transfer or transmission mechanism. The invention suggests building the transfer mechanism with two toggle levers being linked with each other via a toggle lever joint. The end regions of the toggle levers being located opposite to the end regions linked with the toggle lever joint are respectively pivotably linked with a crimping jaw. For such an embodiment the pivoting movement of the crimping jaws coincides with the movement of the toggle levers during the closing movement. 
         [0016]    An activation of the crimping jaw, i.e. a closing movement of the crimping jaws, might require a cam disc. According to the contour of the cam disc a movement of the cam disc displaces the toggle lever joint leading to a closing movement of the crimping jaws. Such embodiment of the invention relies on the finding that the use of a toggle lever mechanism is of advantage for producing large crimping forces. Due to the geometric and kinematic properties the toggle levers build a good transmission for the forces applied by the user. Furthermore, such embodiment uses the cam disc for the force transmission wherein—depending on the outer contour of the cam disc—a further increase of the force on its path towards the crimping jaws is provided. Accordingly, the combination of the toggle lever mechanism and the cam disc builds a “double transmission system”. According to the embodiment shown in the present application, a crimping jaw linked with the toggle lever might be pivoted via an activation of the toggle lever during the closing movement. However, it is also possible that the crimping jaw linked with the toggle lever might perform a translational movement for providing a translational closing movement, see the transfer mechanism disclosed e.g. in U.S. Pat. No. 5,758,729 and U.S. Pat. No. 5,735,353. Also a transfer mechanism comprising such translational movement of at least one crimping jaw should be covered by the present invention. 
         [0017]    According to another embodiment of the invention, the cam disc is coupled with the ratchet-mechanism so that during the rotational movement of the cam disc different ratchet positions of the ratchet-mechanism are passed. During such movement the reached steps of movement is secured by the plurality of ratchet steps. 
         [0018]    Furthermore, the invention suggests connecting the cam disc with an activation element for the transfer of a torsional moment, wherein the activation element is located at the periphery of the crimping pliers or a head of the crimping pliers. The activation element serves for activating the closing mechanism of the crimping pliers. The activation element might be built by an activating lever, wheel, disc or the like, wherein a rotation of the activation element directly or under use of an additional transmission system for further transmission causes a movement of the cam disc. An increase of forces manually applied upon the activation element to an activating torsional moment might be provided by choosing the effective diameter or torque lever of the activation element. However, the activation element might be of any other geometry and having any degree of freedom for the activating movement. 
         [0019]    In general, it is possible that the mentioned open state of the crimping pliers is the state with the largest distance of the crimping jaws from each other. However, according to a variant of the invention it is possible to further open the crimping jaws from such stable open state to a loading state. In the loading state it is possible or simplified to introduce a work piece between the crimping jaws. The crimping jaws are moved by manual activation into the loading state. Such embodiment should be explained on the basis of the following example: in case of the work piece being a hollow cylindrical element (as a fitting or conduit or pipe) the crimping jaws might be opened to a loading state so that the crimping jaws build a bit of tongs or mouths with an opening which is larger than a cross dimension of the work piece. Accordingly, it is possible to introduce the work piece transverse to the longitudinal axis of the work piece into the mouth built by the crimping jaws. For the work piece introduced into the mouth in the above described procedure the crimping jaws are transferred from the loading state into the open state. In the open state the mouth built between the crimping jaws has closed to an amount that it is no longer possible to remove the work piece transverse to the longitudinal axis of the work piece through the mouth. Accordingly, for an extreme use of the crimping pliers it is possible that the user gives the work piece out of his hand which is then held (in loose fit) by the crimping pliers in its open state. Furthermore, with the provision of a loading state it is possible to crimp work pieces with larger dimensions than in case of using crimping pliers having only the open state. 
         [0020]    According to another embodiment of the invention, in the loading state the crimping jaws are biased by a spring element versus the open state. Accordingly, after having introduced the work piece into the crimping pliers and after removing the manual activation of the crimping jaws in the loading state the spring element is responsible for automatically returning the crimping jaws into the open state. 
         [0021]    The movement of the crimping jaws between the loading state and the open state might correlate with a relative movement of the hand levers. However, in case of such relative movement of the hand levers not being desired, it is of advantage to provide some play or gap in the transfer or transmission mechanism between the hand levers and the crimping jaws. Such play or gap is used during the movement of the crimping jaws between the loading state and the open state. It is also possible to provide an additional degree of freedom for decoupling the movement of the crimping jaws and the hand levers for the movement between the loading state and the open state. 
         [0022]    Another embodiment of the invention suggests that during the movement of the crimping jaws between the loading state and the open state the toggle lever joint is moved relative to the cam disc. In particular during the movement between the loading state and the open state the contour of the cam disc is approximately directed along the axis of the movement of the axis of rotation of the toggle lever joint. In the region passed during this movement the cam disc does not have a stop element or limiting element for the toggle lever joint. The toggle lever joint slides along the contour of the cam disc, whereas it is also possible that the toggle lever joint separates from the outer contour of the cam disc. 
         [0023]    Furthermore, the present invention suggests providing a stop element avoiding an automated closing movement of the crimping jaws further than the open state. For manually introducing the closing movement, such stop element has to be overcome. This might be done by removing, turning or folding the stop element. According to another embodiment of the invention, the stop element might be overcome by a counter element contacting the stop element in the open state being automatically removed with the first activation of the hand levers or the activation element. 
         [0024]    Furthermore, it is possible that a spring element is provided biasing the crimping jaws versus the work piece. The spring element might be directly linked with at least one of the crimping jaws. However, it is also possible that the spring element indirectly biases the crimping jaws. E.g. the spring element might bias the transfer or transmission mechanism. In case that the above mentioned stop element secures the open state, in the open state the spring element might be ineffective. However, overcoming the stop element automatically brings the spring element into play wherein the spring element leads to the crimping pliers automatically gripping the work piece between the crimping jaws. Accordingly, the work piece is fixed within the crimping jaws, so that it is also possible to further work only with one hand without gripping the work piece with the other hand. Whereas crimping pliers of the present type usually have an overall length of 60 mm to 90 mm, the present invention also suggests building crimping pliers with an overall length smaller than 400 mm, in particular smaller than 350 mm or 300 mm. Such crimping pliers with decreased dimensions might be used for crimping work pieces also in small spaces, e.g. crimping of conduits or pipes or fittings in air-conditioning units. 
         [0025]    According to another embodiment of the invention, the crimping pliers with any length or a length smaller than 400 mm, in particular smaller than 350 mm or 300 mm, is suitable for manually creating crimping forces being larger than 20,000 N, in particular larger than 25,000 N, 30,000 N, 40,000 N, 50,000 N or 60,000 N. 
         [0026]    The present invention also suggests providing a forced locking mechanism. A “forced locking mechanism” is a locking unit providing the possibility of performing a closing movement at least for a partial movement of the crimping pliers but securing a reached crimping step so that the crimping jaws remain in their reached position also in case of removing the forces applied to the hand levers and/or the activation element. Furthermore, such force locking mechanism might guarantee that it is not possible to reopen the crimping pliers before reaching a predetermined final crimping step correlating with a defined end state of the crimping pliers. Opening the crimping pliers before reaching such end state might be possible only in extraordinary cases by means of activating an emergency unlocking device. Examples for suitable forced locking mechanisms might be taken from DE 101 40 270 B4, U.S. Pat. No. 5,187,968, U.S. Pat. No. 6,026,671, U.S. Pat. No. 5,913,933, DE 198 34 859 C2, DE 197 09 639 A1 and U.S. Pat. No. 6,286,358. 
         [0027]    It is also possible that the crimping pliers are equipped with a locking mechanism. Such “locking mechanism” is a mechanism being used for changing the relative position or orientation of the hand levers without any movement of the relative position or orientation of the crimping jaws. By use of the locking mechanism the overall closing movement of the crimping jaws might be divided in a plurality of partial closing movements with the same relative movement of the hand levers. One example of such a locking mechanism might be taken from U.S. Pat. No. 7,155,954. 
         [0028]    As one option covered by the present invention, the crimping process of the work piece under use of the inventive crimping pliers comprises more than 10, in particular more than 15 or 20, crimping steps secured by the forced locking mechanism. 
         [0029]    Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and the detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0031]      FIG. 1  is a top view showing inner components of crimping pliers according to the invention. 
           [0032]      FIG. 2  is a lateral view of crimping pliers according to  FIG. 1  (in a completed assembling state). 
           [0033]      FIG. 3  shows components of the pliers according to  FIGS. 1 and 2  in a three-dimensional view. 
           [0034]      FIG. 4  is a top view or the pliers according to  FIGS. 1 to 3  in an open state. 
           [0035]      FIG. 5  is a top view of the crimping pliers according to  FIGS. 1 to 4  in a closed state. 
           [0036]      FIG. 6  shows components of the inventive crimping pliers according to  FIGS. 1 to 5  in an enlarged three-dimensional view. 
           [0037]      FIG. 7  shows a cam disc appropriate for use in crimping pliers according to  FIGS. 1 to 6 . 
           [0038]      FIG. 8  shows a hand lever with a fixedly connected supporting plate being used in the crimping pliers according to  FIGS. 1 to 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    Referring now in greater detail to the drawings,  FIG. 1  illustrates crimping pliers  1  having two hand levers  2 ,  3 . Hand lever  2  is fixedly connected with a supporting plate  4 . Supporting plate  4  is used for fixing or pivotably supporting further elements of the crimping pliers  1 . An activation unit  5  is pivotably linked with supporting plate  4 . In the activation unit  5  a pinion gear  6 , a cam disc  7  and a pinion gear  8  are positioned one above the other and fixedly linked by means of pivoting bolt  9 . Pivoting bolt  9  is oriented perpendicular to the drawing plane according to  FIG. 1 . The pivoting bolt  9  is linked with the supporting plate  4  with a rotational degree of freedom along its longitudinal axis. Such pivoting degree of freedom might be provided by a through hole of the supporting plate  4  and a corresponding through hole of another supporting plate  10  located at the opposite side but not shown in  FIG. 1 . 
         [0040]    As can be seen in  FIG. 2 , the pivoting bolt  9  protrudes at the opposite sides of the supporting plates  4 ,  10 . In one end region the pivoting bolt is secured by means of a nut  11 . At the opposite end region the pivoting bolt s fixedly linked with an activation element  12 , here an activation disc. Between nut  11  and supporting plate  4  and/or activation element  12  and supporting plate  10  a disc  13  made of nylon might be interposed. By means of the induced friction and the normal force acting upon the disc  13  the torsional moment or force necessary to rotate the activation element  12 , pivoting bolt  9 , pinion  6 ,  8 , cam disc  7  and nut  11  being part of activation unit  5  might be dimensioned. 
         [0041]    Hand lever  3  is fixedly connected with a supporting plate  14 . Hand lever  3  comprises a through hole for pivotally linking hand lever  3  with supporting plate  14  with pivoting bolt  9 , supporting plate  4  and hand lever  2 . Both supporting plate  4  and supporting plate  14  comprise a pin  15 ,  16  fixedly housed in a bore. These pins  15 ,  16  are used for suspending one base of a spring  17 . The position of the pins  15 ,  16  is chosen such that the tension and spring force of spring  17  results in the hand levers,  2 ,  3  without forces applied by the user being spread apart. Forces applied by the user with the related movement of the hand levers towards each other lead to an increased bias of spring  17 . 
         [0042]    In the transitional region of the supporting plate  14  to the hand lever  3  supporting plate  14  holds a resting lever  18  which is pivoted around an axis vertical to the drawing plane of  FIG. 4 . The resting lever  18  extends to the outer circumference of the pinion  8  and is pressed by means of a torsional spring element (which is not shown in the figures) against the outer circumference of pinion  8 . In the position shown in  FIG. 4  the resting lever  18  has an orientation approximately tangential to the pinion  8 . For the shown embodiment, the resting lever  18  is fixedly connected with a pivoting bolt  19  which is pivotably linked with the supporting plate  14 . The pivoting bolt  19  comprises a manipulation area  20  located externally from the supporting plate  10 . Manipulation of the manipulation area  20  in clockwise direction in  FIG. 4  leads to a pivoting movement of the pivoting bolt  19  with resting lever  18  biasing the torsional spring element and moving the resting lever  18  away from pinion  8  for unlocking the locking connection between resting lever  18  and pinion  8 . For the embodiment shown in  FIG. 4 , the activation area  20  is a slit for a screwdriver. Without manual activation of the activation area  20  by the user the resting lever  18  returns into the position shown in  FIG. 4 . In such position resting lever  18  contacts the outer circumference of pinion  8 . 
         [0043]    Pinion  8  has teeth  21  at its outer circumference cooperating with the front surface of resting lever  18  as follows:
       In a resting or locking position the tip or front surface of resting lever  18  enters into the space between adjacent teeth. Such positive locking locks the rotation of pinion  8  and the whole activation unit  5  in one direction.   However, the tip or front surface of resting lever  18  for a pivoting movement of hand lever  3  versus hand lever  2  contacts a tooth profile of an adjacent tooth. Accordingly forces applied by the user upon hand lever  3  are transferred via the pivoting bolt  19 , a longitudinal force within resting lever  18  to the tooth profile resulting in a pivoting movement of pinion  8  so that the whole activation unit  5  is pivoted in counter-clockwise direction.   A manual pivoting movement of hand lever  3  away from hand lever  2  (or such a movement activated by spring  17 ) results in the resting lever sliding in clockwise direction on the bottom according to  FIG. 4  along the teeth  21  passing one or a plurality of teeth. At the end the resting lever enters into the space between other teeth building a secured position against a rotation into the opposite direction.       
 
         [0047]    Accordingly, on the basis of successive opening and closure of the hand levers  2 ,  3  in a plurality of partial movements or steps a rotation of the activation unit  5  is caused. A reverse movement of the activation unit  5  together with pivoting the hand levers  2 ,  3  apart and with the movement of the resting lever  18  in clockwise direction is avoided by means of the friction between the activation unit and the support plates  4 ,  10 , e.g. under use of the friction determining disc  13 . 
         [0048]    A pivoting bolt  22  is housed in coaxial bores in the supporting plates  4 ,  10 . The pivoting bolt  22  is used for supporting two crimping jaws  23 ,  24  for allowing a pivoting movement around an axis determined by the longitudinal axis of the pivoting bolt  22 . Such pivoting axis has an orientation perpendicular to the drawing plane of  FIG. 4 . The crimping jaws  23 ,  24  in a first approximation might be described as T-shaped in their top view. A pivoting joint  25  built with the pivoting bolt  22  is located in the end region of the longitudinal leg of the T opposite to the transverse leg. The end regions of the crimping jaws  23 ,  24  overlap in the pivoting joint  25 . The outer end region of the transverse leg of the T of the crimping jaws  23 ,  24  has an approximately semi-circular housing  26 ,  27  for a semi-die used for shaping the work piece. Semi-dies might be housed in the housings  26 ,  27  and locked therein and might be in generally known manner unlocked and/or thrown off the crimping jaws  23 ,  24  by manual activation of two activating elements  28 ,  29 . The outer limits  30 ,  31  build a kind of “mouth”  32 , wherein the opening width of the mouth  32  decreases with the closing movement of the crimping jaws  23 ,  24 . The work piece might be introduced between the crimping jaws  23 ,  24  or the semi-dies through the mouth  32 . The end regions of the transverse leg of the T of the crimping jaws  23 ,  24  located opposite to the limits  30 ,  31  are pivotably linked via the pivoting joints  33 ,  34  with the end regions of toggle levers  35 ,  36 . The toggle levers  35 ,  36  are pivotably linked in their abutting end regions via a toggle lever joint  37 . For the shown embodiment, the pivoting joints  33 ,  34  as well as the toggle lever joint  37  are built with bearing bolts oriented perpendicular to the drawing plane according to  FIG. 4 . The bearing bolts are housed in corresponding bores of the related elements. One base of a pulling spring  38  is supported by the supporting plates  4 ,  10 , whereas the other base of the pulling spring  38  is supported by the related toggle lever  35 ,  36  or the toggle lever joint  37 . The pulling spring  38  is preloaded and has an orientation such that the pulling force biases the toggle levers  35 ,  36  versus their coaxial orientation. Such bias means that the pulling force  38  presses the crimping jaws  23 ,  24  in closing direction. Rotatably linked with the toggle lever joint  37  is a roller  39  located in the plane of the cam disc  7 . 
         [0049]    During a pivoting movement of the activation unit  5  the roller  39  rolls along the contour  40  of the cam disc  7 . According to the change of the contour  40  the toggle lever joint  37  is displaced, i.e. an increase of the distance of the contour  40  from the pivoting bolt  9  leads to displacing the toggle lever joint  37  versus the pivoting bolt  22 . The contour  40  of the cam disc  7  comprises a “spiral-shaped” crimping region  41 . In the crimping region  41  continued rotation of the activation unit  5  continuously decreases the distance of the contact area between contour  40  and roller  39  from the rotational axis of the cam disc  7 . A closing state  42  is reached when the roller  39  approaches the end of the crimping region  41 . For further rotation of the cam disc  7 , contour  40  of the cam disc  7  gets out of contact with the roller  39  which is due to the remaining free region  43 . Accordingly, in case of rotating the activation unit  5  further than the closing state  42  the closing or crimping force transferred from the cam disc  5  to the toggle lever joint  37  via roller  39  is removed. However, the force of the pulling springs  38  acts in closing or crimping direction. By manually opening the crimping jaws  23 ,  24 , e.g. by means of the activation element  44 , it is possible to open the crimping jaws  23 ,  24 . Pin  45  is oriented perpendicular to the drawing plane according to  FIG. 1  and fixedly housed in a bore of a protrusion of the toggle lever  35 . With increasing distance of the crimping jaws, pin  45  moves versus a stop element. Such stop element is built by a front region of the supporting plate  14  of hand lever  3 . The stop element avoids that in the open state the crimping jaws are closed by the pulling spring  38 . Pin  45  and stop element  46  are disengaged for another closing movement from the open state by pivoting hand lever  3  versus hand lever  2 . As soon as stop element  46  is overcome or removed, the pulling spring  38  causes a closing movement of the crimping jaws  23 ,  24  bringing the crimping jaws  23 ,  24  automatically in contact with the outer circumference of the work piece. Here, the contact pressure of the crimping jaws  23 ,  24  at the outer circumference of the work piece depend on the stiffness of the pulling force  38 . It is possible that roller  39  moves away from the contour  40  of the cam disc  7 . This is due to the fact that the contact pressure in such case is not caused by contact forces of the contour  40  contacting the roller  39  but caused by the pulling spring  38 . 
         [0050]    For alternative embodiments instead of the shown engagement between pin  45  and stop element  46  any other suitable locking unit or resting unit might be used that could be manually activated and unlocked by the user or might be activated or unlocked according to the shown embodiment by simple manipulation of the hand levers  2 ,  3 . 
         [0051]    From the closed state shown in  FIG. 1  with the pin  45  being in contact with stop element  46  the crimping jaws  23 ,  24  might be manually opened by manually pulling crimping jaws  23 ,  24  apart. During such movement pin  45  moves away from stop element  46  and moves along a guiding front surface  53  of supporting plate  14 . During such movement from the open state to the loading state the free region  43  does not block a movement of the toggle lever joint  37  away from pivoting bolt  22 . 
         [0052]    For crimping a work piece crimping pliers  1  are used as follows: 
         [0053]    Starting from the open state shown in  FIG. 1 , first the crimping jaws  23 ,  24  are manually transferred into the further opened loading state. In such loading state the work piece might be introduced between the crimping jaws through mouth  32 . When removing the manual forces with the work piece located between the crimping jaws the pulling spring  38  closes the crimping jaws  23 ,  24 , until the open state according to  FIG. 1  is reached. Such open state is secured against further closure of the crimping jaws  23 ,  24  via pin  45  and the stop element  46 . However, it is also possible that the work piece without transfer of the crimping pliers into the loading state is introduced between the crimping jaws  23 ,  24  in the open state. With a simple manipulation of the hand levers  2 ,  3  the pin  45  passes stop element  46 . As a consequence, pulling spring  38  is able to pull the toggle lever joint  37  in forward direction correlating with a movement of the crimping jaws  23 ,  24  versus each other so that the work piece is clamped between the crimping jaws  23 ,  24 . The aforementioned movement leads to a small increase of the distance of the roller  39  from the contour  40  of the cam disc  7 . Subsequently, the cam disc  7  is manually rotated, so that the roller  39  comes into contact with the crimping region  41  of the contour  40  of the cam disc  7 . Also a partial movement  49  of the crimping region  41  might be caused by manual rotation of the activation unit  5 . At the end of the manual rotation of the activation unit  5  any reached position at the contour  40  might be secured by means of the engagement of the pinion  8  and rest lever  18 . Now a crimping or further crimping within the partial movement  50  is caused by successive pivoting of the hand levers  2 ,  3  versus each other. Such pivoting movement is coupled with a rotation of the activation unit  5 . Subsequently, the hand levers  2 ,  3  are automatically spread apart by pulling spring  17 . At the end of the crimping region  41  of the cam disc  7  the closed state  42  is reached correlating with the closest position of the crimping jaws  23 ,  24 . Now the crimping process is finished. Further manipulation of the hand levers causes a further rotation of the activation unit, so that the closed state  42  is left. In the free region  43  the activation force applied by the cam disc  7  to the toggle lever joint  37  is removed. Accordingly it is possible that the crimping jaws move away from each other due to an elastic widening of the work piece. However, despite the removed contact between cam disc  7  and roller  39  the pulling spring  38  still presses the crimping jaws  23 ,  24  against the work piece. For removing the crimping pliers  1  from the work piece it is necessary to manually pull the crimping jaws  23 ,  24  in opposite directions, until the pin  45  is locked behind stop element  46  so that the secured open state is built. In case of an opening of the crimping jaws  23 ,  24  further than the open state for removing the work piece a further pivoting movement of the crimping jaws  23 ,  24  might be caused, so that also the loading state might be reached. 
         [0054]    For the shown embodiment, the transfer or transmission mechanism  47  between the hand levers  2 ,  3  and the crimping jaws  23 ,  24  comprises the resting lever  18 , the activation unit  5  with pinion  8 , cam disc  7 , toggle lever joint  37  and the toggle levers  35 ,  36 . The transfer or transmission mechanism  47  is used for transferring forces and moments between the hand levers  2 ,  3  and the crimping jaws  23 ,  24 , for providing a transmission ratio and for determining kinematics of closing the crimping jaws. 
         [0055]    For the shown embodiment, on both sides of the cam disc  7  a pinion  8 , a resting lever  18  and a pulling spring  17  are located. The forces acting upon the teeth  21 , the resting lever  18  and the pulling spring  17  divide. Furthermore, such design leads to a symmetric force transfer in the transfer or transmission mechanism  47 . 
         [0056]    As can be seen in  FIGS. 2 ,  3  and  6 , the main components of the crimping pliers  1  have a plate-like design. 
         [0057]    A closing mechanism  48  is built with the activation unit  5 . The activation unit  5  is manually activated and acts via the toggle lever joint  37  and the toggle levers  35 ,  36  on the crimping jaws  23 ,  24  for causing the closing movement. 
         [0058]    It is possible that the closing mechanism  48  by manual activation of the activation unit  5  causes a movement of the crimping jaws  23 ,  24  towards each other in a partial movement  49 , whereas in the subsequent partial movement  50  the main crimping process is caused by means of activation of the hand levers  2 ,  3 . For the shown embodiment in the partial movements of the closing process the closing might be activated by manual activation of the activation unit  5  and the closing mechanism  48  or by manual activation of the hand levers. For the transition from the partial movement  49  to the partial movement  50 , so for the start of the manipulation of the hand levers, a starting state  51  is reached. For another crimping process the partial movement  49 ′ might be shorter or longer leading to a different starting state  51 ′. The cooperation between resting lever  18  and teeth  21  and the bias of the pulling spring  17  builds a ratchet-mechanism  52  or a locking mechanism. 
         [0059]    The shown embodiment of the crimping pliers is only one possible embodiment. The disclosed inventive features might partially or completely be integrated into other types of crimping pliers, in particular those described in the patent applications and patents of the applicant. To give some examples, the features of the invention might be used for pliers of the following types:
       DE 40 23 337 C1, DE 44 27 553 C2, DE 198 32 884 C1 and DE 100 56 900 C1 show pliers having dies being closed by a translational movement, wherein in some embodiments the dies are guided by an O-shaped guiding frame.   Pivotable crimping jaws for cable connectors being introduced transverse to the main plane of the pliers are disclosed in DE 37 08 727 C2 or DE 199 24 087 C2. Similar pliers, here used for cable shoes, are described in DE 197 09 639 A1. Also DE 198 02 287 C1 discloses pliers with pivotable crimping jaws.   The invention might also be applied for crimping pliers with a C-shaped head of the pliers. The crimping jaws or dies are displaced between the transverse legs of the C, see DE 102 42 345 B3 and DE 197 13 580 C2. DE 197 53 436 C2 shows the option of designing the pliers with a C-shaped head or with pivotable crimping jaws.   DE 40 26 332 C2 discloses crimping pliers wherein the work piece is introduced from the front surface of the pliers in longitudinal direction of the pliers between the jaws or dies.   Examples of forced locking mechanisms for different types of pliers also suitable for cumulative use with the present invention are described in DE 101 40 270 B4, DE 40 39 435 C1, DE 198 07 737 C2, DE 197 13 580 C2, DE 198 34 859 C2, DE 197 09 639 A1 and DE 199 24 086 C2.   DE 198 32 884 C1 discloses pliers with a locator used for positioning the work piece relative to the head of the pliers.   Crimping pliers with kinematics being adaptive by changing the linking point of a pressure rod in a toggle lever mechanism is known from DE 198 34 859 C2.   DE 199 63 097 C1 discloses a design with a hand lever having two parts. The angle between the two parts is adjustable for providing different opening angles of the outer part of the hand lever relative to the other hand lever for the same position of the crimping jaws.   A cam drive mechanism, here for cutting pliers, is known from DE 101 32 413 C2.   A locking mechanism that might be integrated into crimping pliers according to the present invention might be taken from DE 103 46 241 B3.   DE 10 2007 001 235 discloses crimping pliers with three or two hand levers having a switchable transfer or transmission mechanism such that for two partial movements the hand levers might be moved in different directions.       
 
         [0071]    Many variations and modifications may be made to the preferred embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of the present invention, as defined by the following claims.