Crimping tool

Abstract

The invention relates to pressing or crimping pliers (1). According to the invention a spring device (35) (which is e.g. embodied as U-shaped leaf spring (36)) is used in the crimping pliers. In an equilibrium position (48) the leaf spring (36) is trapped between stops (49, 50). If the pressing or crimping pliers (1) are moved from the equilibrium position (48) in closing direction the leaf spring (36) is biased by a follower (54) such that the leaf spring (36) generates an opening force. In reversed direction the opening movement of the pressing or crimping pliers (1) from the equilibrium position (48) leads to a bias of the leaf spring (36) by a follower (55) such that the leaf spring is able to generate a closing force. According to the invention it is possible to provide that the pressing or crimping pliers (1) automatically and elastically open when reaching the closed position. Furthermore, a workpiece inserted into the pressing or crimping pliers (1) is clamped by a closing force and secured in this way.

Claims

1. Pliers for pressing or crimping a workpiece, the pliers comprising: a) two pliers jaws, b) two hand levers, c) a driving mechanism which drivingly couples the hand levers to the pliers jaws such that it is possible to induce a working stroke from an open position of the pliers jaws into a closed position of the pliers jaws by a manually induced relative movement of the hand levers, the working stroke comprising: ca) an equilibrium position between the open position and the closed position of the pliers jaws, cb) a first working stroke part located between the open position and the equilibrium position of the pliers jaws configured to clamp the workpiece between the pliers jaws and cc) a second working stroke part located between the equilibrium position and the closed position of the pliers jaws configured to press or crimp the workpiece clamped between the pliers jaws, d) a spring device positioned on the driving mechanism which biases the pliers jaws toward and away from each other and which da) in the equilibrium position does not apply a net force to the pliers jaws, db) in the first working stroke part applies a closing force to the pliers jaws to bring the pliers jaws into the equilibrium position without manual application of force to the two hand levers and dc) in a second working stroke part applies an opening force to the pliers jaws such that when the second working stroke part is completed and the hand levers are released the pliers jaws return to the equilibrium position.

2. The pliers of claim 1 wherein the spring device comprises a) a closing spring which produces the closing force in the first working stroke part and b) an opening spring which produces the opening force in the second working stroke part.

3. The pliers of claim 1 wherein the spring device comprises a spring which produces both a) the closing force in the first working stroke part as well as b) the opening force in the second working stroke part.

4. The pliers of claim 3 wherein the spring is embodied as a U-shaped bending spring or leaf spring.

5. The pliers of claim 4 wherein spring arms of the U-shaped bending spring or leaf spring extend in a direction of a longitudinal axis of a pliers head or in the direction of the hand levers when closed relative to each other.

6. The pliers of claim 1 wherein a) at least one stop is provided which defines an external displacement of a spring base of the spring device, b) at least one follower is provided and c) in one of said first working stroke part and said second working stroke part, a follower moves the spring base of the spring device away from the stop.

7. The pliers of claim 6 wherein a) the stop is fixed at or assembled to a pliers head or supported by a pliers head and b) the follower is fixed at or assembled to the one of the pliers jaws which is moved relative to the pliers head over the working stroke or the follower is formed by the one of the pliers jaws which is moved relative to the pliers head over the working stroke.

8. The pliers of claim 1 wherein a) a forced locking unit is provided which secures the pliers jaws in a reached partially closed position against an opening movement and allows an opening movement of the pliers jaws only when the second working stroke part has been completed and b) the spring device moves the pliers jaws into the equilibrium position when the working stroke has been completed.

9. The pliers of claim 1 wherein the pliers comprise a latching device or a locking device which secures the open position of the pliers jaws.

10. The pliers of claim 9 wherein a spring of the spring device is multifunctional in that the spring a) produces the opening force or the closing force and b) produces a latching force of the latching device or a locking force of the locking device.

11. The pliers of claim 10 wherein a) the spring of the spring device is a U-shaped bending spring or leaf spring b) a spring arm of the U-shaped bending spring or leaf spring forms a latching spring arm of the latching device and c) the latching spring arm elastically supports a latching element which is latched with a counter latching element which is moved relative to the latching element over the working stroke.

12. The pliers of claim 11 wherein a) the pliers jaws are embodied as a fixed pliers jaw and a movable pliers jaw b) the hand levers are embodied as a fixed hand lever and a movable hand lever, c) a fixed pliers part forms the fixed pliers jaw and the fixed hand lever, d) a movable pliers part forms the movable pliers jaw and the movable pliers part is linked for being pivoted by a pivot joint to the fixed pliers part, e) the movable hand lever is linked for being pivoted by a pivot joint to the fixed pliers part and f) the movable hand lever is connected by the driving mechanism to the movable pliers part.

13. The pliers of claim 12 wherein the movable hand lever forms the counter latching element.

14. The pliers of claim 1 wherein a) the pliers jaws are embodied as a fixed pliers jaw and a movable pliers jaw, b) the hand levers are embodied as a fixed hand lever and a movable hand lever, c) a fixed pliers part forms the fixed pliers jaw and the fixed hand lever, d) a movable pliers part forms the movable pliers jaw and the movable pliers part is linked for being pivoted by a pivot joint to the fixed pliers part, e) the movable hand lever is linked for being pivoted by a pivot joint to the fixed pliers part and f) the movable hand lever is connected by the driving mechanism to the movable pliers part.

15. The pliers of claim 14 wherein the driving mechanism comprises a toggle lever drive.

16. The pliers of claim 14 wherein the pivot joint by which the movable pliers part is linked for being pivoted to the fixed pliers part is located in a half of the fixed pliers part on a side of the fixed pliers part remote from a pliers head.

17. The pliers of claim 1 wherein the driving mechanism comprises a toggle lever drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention is further explained and described with respect to preferred exemplary embodiments illustrated in the drawings.

(2) FIG. 1 shows crimping pliers in a three-dimensional exploded view.

(3) FIG. 2 shows the crimping pliers of FIG. 1 in a three-dimensional view.

(4) FIG. 3 shows components of the crimping pliers of FIGS. 1 and 2 for illustrating the driving kinetic in a side view.

(5) FIGS. 4, 6, 8, 10 show the crimping pliers of FIGS. 1 to 3 in different operational positions in side views.

(6) FIGS. 5, 7, 9, 11 show details V, VII, IX, XI of the crimping pliers of FIGS. 4, 6, 8, 10.

(7) FIG. 12 shows an alternative embodiment of crimping pliers in a side view.

(8) FIG. 13 shows a detail XIII of the crimping pliers of FIG. 12.

(9) FIG. 14 shows different spring characteristics of a spring device of pressing pliers or crimping pliers.

DETAILED DESCRIPTION

(10) FIGS. 1 to 11 show crimping pliers 1 in a plate-design. The crimping pliers 1 comprise a fixed pliers part 2 and a movable pliers part 3. The fixed pliers part 2 comprises two fixed pliers part plates 4a, 4b. The movable pliers part 3 comprises two movable pliers part plates 5a, 5b. The fixed pliers part 2 comprises a fixed pliers jaw 6, a connecting portion 7 and a fixed hand lever 8. For the shown embodiment the fixed pliers part plate 4a forms the fixed pliers jaw 6, the connecting portion 7 and the fixed hand lever 8. Instead, the fixed pliers part plate 4b only forms the fixed pliers jaw 6 and the connecting portion 7. The movable pliers part 3 comprises a movable pliers jaw 9. The movable pliers jaw 9 is held by a pivoting support 10. Here, the movable pliers part plates 5a, 5b comprise two parts, namely the pliers jaw plates 11a, 11b and the pivoting support plates 12a, 12b.

(11) The movable pliers part 3 is supported at the fixed pliers part 2 for being pivoted about a pivot axis 14 by a pivot joint 13. For the shown embodiment this is provided by a pivot bolt 15. The pivot bolt 15 extends through through bores 16a, 16b, 16c, 16d of the movable pliers part plates 5a, 5b and the fixed pliers part plates 4a, 4b for allowing a pivoting movement. Here, the two movable pliers part plates 5a, 5b are accommodated between the fixed pliers part plates 4a, 4b. The pliers jaw plates 11a, 11b are attached to the pivoting support plates 12a, 12b and supported by the pivoting support plates 12a, 12b in a way such that the pliers jaw plates 11a, 11 b extend in parallel planes defined by the fixed pliers part plates 4a, 4b and such that these move in the aforementioned planes during the pivoting movement.

(12) Approximately in the middle of the pivoting support plate 12 an end region of a pressure lever 18 (which is here formed by two pressure lever plates 19a, 19b) is linked by a pivot joint 17 to the movable pliers part 3. For the shown embodiment the pivot joint 17 is formed by a pivot bolt 20. The pivot bolt 20 is accommodated in through bores 21a, 21b, 21c, 21d of the pressure lever plate 19b, the pivoting support plate 12b, the pivoting support plate 12a and the pressure lever plate 19a. In this way a pivot axis 22 of the pivot joint 17 is defined. For the shown embodiment the two pressure lever plates 19 are not arranged within the fixed pliers part plates 4a, 4b but outside from the same. For this reason the pivot bolt 20 extends through elongated holes 23a, 23b of the fixed pliers part plates 4a, 4b. The elongated holes 23a, 23b are formed and arranged in a way such that the fixed pliers part plates 4a, 4b do not impede the movement of the pivot bolt 20 with the pivoting movement of the movable pliers part 3.

(13) A movable hand lever 24 (which here comprises two movable hand lever plates 25a, 25b) is supported at the fixed pliers part 2 for being pivoted by a pivot joint 26 having a pivot axis 27. For this purpose the fixed pliers part plate 4b, the hand lever plate 25b, the hand lever plate 25a and the fixed pliers part plate 4a comprise through bores 28a, 28b, 28c, 28d. A pivot bolt 29 extends through the through bores 28a, 28b, 28c, 28d. The pivot bolt allows a relative pivoting movement of the movable hand lever 24 relative to the fixed pliers part 2.

(14) The pressure lever 18 is connected by a pivot joint 30 to the hand lever 24 for being pivoted. For this purpose the pressure lever plates 19a, 19b comprise through bores 31a, 31d. At a position adjacent to the through bores 28b, 28c the hand lever plates 25a, 25b comprise through bores 31b, 31c. A pivot bolt 32 extends through the through bores 31b, 31c, allowing a pivoting movement. Due to the fact that for this purpose the pivot bolt 32 has to pass through the fixed pliers part plates 40a, 40b, the fixed pliers part plates 4a, 4b comprise elongated holes 33a, 33b. The elongated holes 33a, 33b provide that the motional degree of freedom of the pivot bolt 32 is not impeded.

(15) The aforementioned couples of the components or plates extend symmetrically on both sides of a centered pliers plate plane. In the centered pliers plate plane a spring 34 is arranged which forms a part of a spring device 35. For the shown embodiment the spring 34 is embodied as U-shaped leaf spring or bending spring 36.

(16) A forced locking unit 37 is used in the crimping pliers 1. The forced locking unit 37 comprises a locking pawl 38. The locking pawl is here supported by a locking pawl shaft 39. The locking pawl shaft 39 is supported for being rotated by the pressure lever plates 19a, 19b. The locking pawl shaft 39 extends (without limiting the motional degree of freedom) through through recesses 40a, 40b of the fixed pliers part plates 4a, 4b. In the region of the interaction with the locking pawl 38 and at its outer circumference the hand lever 24 forms a locking toothing. During the closing movement of the hand lever 24, due to the bias by a spring 42 the locking pawl 38 ratchet-like slides along the locking toothing 41. The geometry of the locking pawl 28 and the locking toothing 41 are here chosen such that by an engagement of the locking pawl 38 with the locking toothing 41 a movement in reversed direction is impossible. If instead the closed position of the crimping pliers 1 is reached, the locking pawl 38 has passed the locking toothing 41. Accordingly, the locking pawl 38 is able to turn due to the pulling force generated by the spring 42. After the turn the locking pawl 38 is enabled to slide along the locking toothing 41 during an opening movement.

(17) In FIG. 2 it can be seen that the pliers jaws 6, 9 exchangeably support a die 43, 44. Preferably, here a connection of the pliers jaws 6, 9 to the dies 43, 44 is used as described in the patent publication DE 19 802 287 C1 corresponding to U.S. Pat. No. 6,053,025 A.

(18) The driving kinetic can be explained on the basis of the representation according to FIG. 3: due to the support of the movable pliers part 3 with the pivoting support 10 and the pliers jaw plate 11 by the pivot joint 13 at the fixed pliers part 2 a relative movement of the pliers jaws 6, 9 is possible. This relative movement of the pliers jaws 6, 9 is induced by a pivoting movement of the hand lever 24 relative to the fixed pliers part 2 about the pivot joint 26. Between the pivot joints 26, 30 the hand lever 24 forms a first toggle lever 45. Between the pivot joints 17, 30 the pressure lever 18A forms a second toggle lever 46. Here, the pivot joint 30 forms the toggle joint of a toggle lever drive 47 comprising the toggle levers 45, 46. The toggle lever drive 47 transforms the pivoting movement of the hand lever 24 to a pivoting movement of the movable pliers part 3 relative to the fixed pliers part 2.

(19) In the following the spring device 45 is explained more in detail:

(20) According to FIG. 4 the crimping pliers 1 are in an equilibrium position 48. In the equilibrium position 48 the opening angle of the hand levers is e.g. in the region of 40° to 50°, in particular 45° to 48°. The fixed pliers part 2 supports two stops 49, 50. Here, the stops 49, 50 are embodied as bolts carried in through bores of the fixed pliers part plates 4a, 4b. In the equilibrium position 48 spring arms 51, 52 (formed by the approximately parallel side legs of the U) of the U-shaped leaf spring or bending spring 36 contact associated stops 49, 50 at the outside. Here, it is possible that in the equilibrium position 48 the leaf spring or bending spring 36 and the spring arms 51, 52 are not pre-tensioned. However, it is also possible that the leaf spring or bending spring 46 is tensioned so that the leaf spring or bending spring 46 is pre-tensioned between the stops 49, 50.

(21) On the sides of the leaf spring or bending spring 36 facing away from each other (and preferably in the free end regions of the spring arms 51, 52) the movable pliers part 3 supports or carries followers 54, 55. For the shown embodiment the followers 54, 55 are formed by follower bolts which are held in bores of the movable pliers part plates 5a, 5b. Here, the follower bolt forming the follower 54 is multifunctional because the follower bolt forming the follower 54 also serves for mounting the pliers jaw plate 11 to the pivoting support 10. In the equilibrium position 48 shown in FIGS. 4 and 5 the followers 54, 55 initially contact the leaf spring on bending spring 36 without here a significant contact force being generated.

(22) FIGS. 6 and 7 show the crimping pliers 1 in a closed position 53 wherein an angle of the hand levers 8, 24 is in the region of 0° to 10° (preferably in the region of 0° to 5°).

(23) The pivoting movement of the movable pliers part 3 from the equilibrium position 48 according to FIGS. 4 and 5 into the closed position 53 according to FIGS. 6 and 7 (and the concurrent relative movement of the follower 54, 55 relative to the fixed pliers part 2) leads to the result that the follower 55 moves away from the spring arm 51. However, during this movement the follower 55 is pressed to an increasing extent against the spring arm 52. Accordingly, the leaf spring or bending spring 36 is additionally biased. The returning force of the leaf spring or bending spring 36 caused thereby results in an opening force being directed in opening direction. During the biasing of the leaf spring or bending spring 36 caused by the follower 54 the leaf spring or bending spring 36 separates from the stop 50. The leaf spring or bending spring 36 to an increasing extent moves away from the stop 50 up to the arrival in the closed position 53. When reaching the closed position according to FIGS. 6, 7 and when the forced locking unit 37 allows the opening movement of the hand levers 8, 24, for a removal of the hand forces the crimping pliers 1 elastically open in an automatic way. Due to the effect of the spring device 35 the crimping pliers 1 automatically return from the closed position 53 into the equilibrium position 48.

(24) If instead the crimping pliers 1 are transferred from the equilibrium position 48 according to FIGS. 4 and 5 into a partially open position 56 according to FIGS. 8 and 9 or into a (maximally) open position 57 according to FIGS. 10 and 11 (where e.g. in the partially open position 56 the opening angle of the hand levers 8, 24 is in the region of 60° to 70°, preferably 65° to 68° and the opening angle of the hand levers 8, 24 in the open position 57 is in the range of 80° to 100° preferably 85° to 95°), the relative movement of the movable pliers part 3 relative to the fixed pliers part 2 leads to the result that the follower 54 separates from the spring arm 52 whereas the spring arm 52 is still supported at the stop 50. However, simultaneously a force is applied by the follower 55 to the spring arm 51 which increases with the opening movement. The increasing force leads to an increasing deformation of the leaf spring or bending spring 36 and to the movement of the spring arm 51 away from the stop 49. The increasing bias of the leaf spring or bending spring 36 leads to the consequence that the leaf spring or bending spring 36 applies a closing force upon the pliers part 2, 3 and so the pliers jaws 6, 9. The closing force has an orientation to restore the equilibrium position 48.

(25) For the shown embodiment in an optional configuration the crimping pliers 1 comprise a latching device 58. By the latching device 58 it is possible to latch the open position in a way such that the open position 57 is maintained despite of the applied closing force of the spring device 35. Only when manually over-pressing the latched open position 57 (which leads to a reduction of the latching force or a complete removal of the latching force of the latching device 58) it is possible that by means of the closing force provided by the leaf spring or bending spring 36 the spring device 35 automatically restores the equilibrium position 48. In the latching device 58 a latching element 60 (which in particular forms a protrusion [or a recess]) is pressed by a latching spring 59 against a counter latching element 61 (which in particular forms a recess [or a protrusion]). Here, (at least in the neighborhood of the open position 57) a movement of the hand levers 8, 24 or the pliers jaws 6, 9 relative to each other leads to a relative movement of the latching element 60 and the counter latching element 61.

(26) For the shown embodiment the latching spring 59 of the latching device 58 is formed by a latching spring arm 62 of the leaf spring or bending spring 36 (here in a longitudinal section which extends transverse to the spring arm 52 in the direction of the hand lever 24). In the free end region of the latching spring arm 62 cooperating with the hand lever 24 the latching spring arm 62 carries a pin 63 which forms the latching element 60.

(27) The counter latching element 61 is in this case formed by a recess 64 of a latching contour 65 of the hand lever 24. When approaching the open position 57 the pin 63 slides along the latching contour 65 under an elastic bias by the latching spring arm 62. When reaching the open position 65, due to the elastic bias of the latching spring arm 62 the pin 63 is latched in the recess 64. Here, the contact force of the latching element 60 with the counter latching element 61 (so the pre-tension of the latching spring arm 62) and the geometry of the latching contour 65 (in particular the depths of the recess 64 and the inclination of the latching contour 65 in the region of the recess 64) are chosen such that the closing force of the spring device 35 is not able to overcome the latching effect of the latching device 58. Instead, for this purpose the user has to move the hand lever 24 in closing direction such that the latching element 60 can be released from the counter latching element 61 (so the pin 63 is able to exit from the recess 64)

(28) It is possible that the leaf spring or bending spring 36 is supported for being pivoted by the movable pliers part 3.

(29) As an example FIGS. 12 and 13 show another embodiment of the spring device 35 which is also covered by the invention. In this case a coupling arm 67 of the hand lever 24 extends into the region of the movable pliers part 3. Here, in the equilibrium position 48 shown in FIGS. 12 and 13 the free end region of the coupling arm 67 is trapped between the two compression spring 68, 69. The compression spring 68 forms an opening spring 70 and the compression spring 69 forms a closing spring 71.

(30) For the effect of the compression springs 68, 69 there are different options:

(31) a) It is possible that the compression springs are not pre-tensioned in the equilibrium position 48 shown in FIGS. 12 and 13. In this case an opening of the hand levers 8, 24 leads to the result that the coupling arm 67 moves away from the opening spring 70. At the same time the closing spring 71 is compressed by the coupling arm 67 so that the closing spring 71 is able to generate the required closing force. In reverse direction a closing movement of the hand levers 8, 24 from the equilibrium position 48 leads to the result that the coupling arm 67 moves away from the closing spring 71. The opening spring 70 is biased to an increasing extent. In this way the required opening force can be generated.

(32) b) It is also possible that in the equilibrium position 48 the compression springs 68, 69 do not apply any force upon the coupling arm 67. However, the compression springs 68, 69 are pre-tensioned (with the same pre-tensional forces or differing pre-tensional forces). An embodiment of this type is shown in FIGS. 12 and 13. In this case the expansion of the compression springs 68, 69 and the generation of a contact force of the same with the coupling arm 67 in the equilibrium position 48 is prevented because the movement of the compression spring 68, 69 coincides with the movement of a spring rod. The spring rod carries ring collars 72, 73. In the equilibrium position 48 the ring collars 72, 73 contact stops 49, 50 (which are here formed by the guidances of the compression springs 68, 69 or by the spring rods). A pivoting movement of the hand levers 8, 24 from the equilibrium position 48 requires to overcome the pre-tension of the respective compression spring 68, 69 arranged in moving direction. The compression spring 68, 69 not being arranged in movement direction is not able to follow the movement because this compression spring 68, 69 is hindered from a relaxation by the contact of the ring collar 72, 73 with the stop 49, 50. Accordingly, the stops 49, 50 define a maximum of the displacement of the compression springs 68, 69. For this embodiment the coupling arm 67 forms the followers 54, 55.

(33) As an optional variant in the embodiment according to FIGS. 12 and 13 the latching device 58 comprises a latching element 60 (here a pin 63) carried by the fixed pliers part 2. The latching element 60 interacts with a latching contour 65 supported by an elastic latching spring arm 62 of the hand lever 24. The latching contour 65 forms the counter latching element 61, here a recess 64.

(34) FIG. 14 shows different characteristics 74, 75, 76 for the spring force 77 of the spring device 35 in dependence on the opening angle 78 of the hand levers 8, 24. These characteristics 74, 75, 76 represent general schematic spring force curves which can be achieved for any design of the spring device 35 and the pressing pliers or crimping pliers 1. In the characteristics 74, 75, 76 the origin of the abscissa corresponds to the closed position 53. Here, also the equilibrium position 48 is marked. The given maximum values of the characteristics 74, 75, 76 correlate to the open position 57. On the ordinate positive values represent an opening force. Negative values of the ordinate represent a closing force of the spring device 35.

(35) For the characteristic 74 shown with solid line there is a smooth progress of the spring force of the spring device 35 without any jump. However, dependent on the spring characteristic of the used spring also a curved progress is possible. A characteristic 74 of this type can be provided already by one single spring, the not pre-tensioned equilibrium position of the spring corresponding to the equilibrium position 48. In this case, for a movement out of the equilibrium position 48 the single spring generates the opening force or the closing force dependent on the movement direction.

(36) For the embodiment of FIGS. 1 to 11 generally a characteristic according to characteristic 74 can be achieved in the case that the leaf spring or bending spring 46 is not pre-tensioned in the equilibrium position 38. However, care has to be taken that in some cases due to differing leverages of the followers 54, 55 the characteristic 74 might have a kink in the region of the equilibrium position 48. This can purposefully be used in the constructive design if differing inclinations of the characteristic 74 in the working stroke parts are desired. For the embodiment shown in FIGS. 12 and 13 a characteristic 74 is used if in the equilibrium position 48 the opening spring 70 and the closing spring 71 are not pre-tensioned and the opening spring 70 and the closing spring 71 comprise one and the same spring stiffness.

(37) The characteristic 75 shown in dashed line comprises a jump at the equilibrium position. This might be desirable if a notably stable equilibrium position 48 has to be provided with comparatively high returning forces into the same and/or if in the two working stroke parts the characteristic 75 should comprise a comparatively small inclination at a high force level. A characteristic 75 of this type can be achieved for the embodiment according to FIGS. 1 to 11 by pre-tensioning the leaf spring or bending spring 36 in the equilibrium position 48 between the stops 49, 50. The extent of the pre-tension defines the heights of the jump in the characteristic 75. Instead, the inclination of the characteristic 75 in the two working stroke parts is defined by the bending stiffness of the leaf spring or bending spring 46. For the embodiment of FIGS. 12 and 13 a characteristic 75 can be achieved by pre-tensioning the opening spring 70 and the closing spring 71 in the equilibrium position 48, where the opening spring 70 and the closing spring 71 (due to the interaction between the ring collars 72, 73 and the stops 49, 50) do not generate a force acting upon the followers 54, 55.

(38) Finally, FIG. 14 with dotted line shows a characteristic 76 where it is not the exact equilibrium position 48 which is stable. Instead, the spring device in a neighboring region of the equilibrium position 48 does not generate a spring force so that this neighboring region is multi-stable. Only when leaving this neighboring region the shown characteristic 76 comprises a jump with a then increasing opening force respectively closing force. A characteristic 76 of this type can be achieved in the case that for the embodiment of FIGS. 1 to 11 in the equilibrium position the two followers 54, 55 do not already contact the leaf spring or bending spring as shown but these are arranged at a distance from the same. The distance of the followers 54, 55 from the leaf spring or bending spring 36 then defines the dimension of the neighboring region of the equilibrium position 48 for which no opening force and no closing force is generated. The characteristic resulting therefrom leads to jumps of the same heights when leaving the neighboring region (differing from the shown characteristic 76) with subsequent same inclinations of the characteristic in the working stroke parts 79, 80.

(39) For the embodiment shown in FIGS. 12 and 13 a characteristic as the shown characteristic 76 can be achieved if also here in the equilibrium position 48 the followers 54, 55 are arranged with a distance from the compression springs 68, 69 contacting the stops 49, 50. By the choice of differing pre-tensions of the compression springs 68, 69 it is possible that (corresponding to the shown characteristic 76) the jumps when leaving the neighboring region of the equilibrium position 48 have differing heights. However, it is also possible that compression springs 68, 69 having differing stiffnesses are used so that in the two working stroke parts the characteristic 76 comprises different inclinations.

(40) It is possible that any other springs as e.g. pulling springs are used between any components of the crimping pliers 1 moved relative to each other during the working stroke without leaving the frame of the invention. Outside from the equilibrium position 48 (or outside from the above explained neighboring region wherein the spring device 35 does not generate a force) a first working stroke part 79 denotes operating positions of the crimping pliers 1 between the open position 57 and the equilibrium position 48 whereas a second working stroke part 80 characterizes operating positions of the crimping pliers 1 between the equilibrium position 48 and the closed position 53. The whole stroke between the open position 57 and the closed position 53 is denoted as working stroke 81.

(41) With respect to the functionally it is possible to distinguish on the one hand the axial section with the hand levers 8, 24 and on the other hand a pliers head 82 at the crimping pliers 1. In the region of the pliers head 82 the pliers jaws 6, 9 with the dies 43, 44, the driving connection or mechanism with the toggle lever drive 47, the spring device 35 and the forced locking unit 37 are arranged.

(42) In the present specification the invention has primarily been explained in connection with crimping pliers 1. A corresponding design is also possible for pressing pliers. The inventive features and designs can e.g. be integrated in pressing pliers according to the prior art mentioned above.

(43) Here, the design of crimping pliers 1 has been described for a plate-design where components are partially formed by a couple of parallel plates. In fact, the same base principle can be embodied in crimping pliers 1 if there are no couples of plates but there is only one single constructional element of this type.

(44) Within the frame of the present description constructional elements corresponding to each other or being similar with respect to the function and/or the design are denoted with the same reference numerals but differing additional letters a, b, . . . . In some cases reference is made to these constructional elements without making use of the additional letter.

(45) 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.