Crimping pliers

1. Crimping pliers for crimping a workpiece comprising:

a) two drive elements, comprising a fixed hand lever and a movable hand lever,

b) a pliers head comprising a first actuation element and a second actuation element which are connected by a drive mechanism and a spring element to the drive elements,

c) at least two dies for crimping the workpiece,

d) two spring bases,

wherein

d) the first actuation element comprises guidances, wherein each said guidance guides the associated die, the second actuation element comprises actuation surfaces for the at least two dies and a relative movement between the first and second actuation element results in a movement of the at least two dies relative to the guidances which is caused by the contact of the acuation surfaces with the at least two dies such that the at least two dies are actuated for crimping the workpiece between the at least two dies,

e) the spring element comprises a force-displacement-compensation element and

f) the spring element is arranged in the pliers head and directly linked with one of the spring bases to the movable hand lever and with the other of the spring bases to the second actuation element.

2. Crimping pliers of claim 1 , wherein the spring element comprises a bending beam.

3. Crimping pliers of claim 2 , wherein the spring element comprises a plate design.

4. Crimping pliers of claim 1 , wherein the spring element extends in a circumferential direction around a die axis.

5. Crimping pliers of claim 4 , wherein the spring element comprises a spring having the shape of an arc of a circle or a spiral spring.

6. Crimping pliers of claim 2 , wherein the bending beam has a bending stiffness varying along its longitudinal axis.

7. Crimping pliers of claim 6 , wherein the geometric moment of inertia of the bending beam increases from the one of the spring bases which is linked to the moveable hand lever to a cross-section of the bending beam located opposite the spring base in a circumferential direction.

8. Crimping pliers of claim 7 , wherein the geometric moment of inertia of the bending beam is symmetrical to a symmetry axis which runs approximately through the one of the spring bases which is linked to the moveable hand lever and through the cross-section of the bending beam located opposite the spring base in a circumferential direction.

9. Crimping pliers of claim 1 , wherein

a) the actuation elements are pivoted relative to each other around the die axis,

b) the at least two dies are mounted for a pivoting movement relative to the guidances and

c) the relative pivoting movement of the actuation elements results in a pivoting movement of the at least two dies relative to the guidances by the contact of the actuation surfaces with the at least two dies.

10. Crimping pliers of claim 1 , wherein the drive mechanism comprises a toggle lever mechanism.

11. Crimping pliers of claim 10 , wherein the toggle lever mechanism comprises a roller and a guiding part, wherein over the working stroke, the roller rolls along the guiding part.

12. Crimping pliers of claim 11 , wherein

a) the guiding part is mounted to the drive element at which one of the actuation elements is mounted and

b) the roller is mounted for being rotated to the other drive element at which the spring element is linked which is connected to the other actuation element.

13. Crimping pliers of claim 11 , further comprising a second spring element which provides a contact force of the roller at the guiding part.

14. Crimping pliers of claim 13 , wherein one spring base of the second spring element biases the spring element.

15. Crimping pliers of claim 1 , further comprising a forced locking unit.

16. Crimping pliers of claim 15 , wherein the forced locking unit comprises a toothed latching lever

a) which is rotatably mounted about a pivot axis of the roller and

b) of which an end region opposing the toothing for latching is connected by an elongated hole to the drive element at which the mounting part is mounted.

17. Crimping pliers of claim 1 , wherein by use of

a) the force-displacement-compensation due to the force-displacement-compensation element and/or

b) the movement of the roller along the curved track of the guiding part with a change of the dimensional and angular properties of the toggle lever mechanism,

it is possible to crimp workpieces of different cross-sectional areas, wherein for two different workpieces crimped with the crimping pliers, the cross-sectional areas differ by at least a factor of 30.

18. Crimping pliers of claim 1 , wherein the pliers head further comprises a positioning device for at least one workpiece.

19. Crimping pliers of claim 1 , wherein the spring element is guided by a guidance.

20. Crimping pliers of claim 2 , wherein the spring element extends in a circumferential direction around a die axis.

21. Crimping pliers of claim 3 , wherein the spring element extends in a circumferential direction around a die axis.

22. Crimping pliers of claim 3 , wherein the bending beam has a bending stiffness varying along its longitudinal axis.

23. Crimping pliers of claim 22 , wherein the geometric moment of inertia of the bending beam increases from the spring base at which the bias by the drive mechanism is applied to a cross-section of the bending beam located opposite the spring base in a circumferential direction.

24. Crimping pliers of claim 23 , wherein the geometric moment of inertia of the bending beam is symmetrical to a symmetry axis which runs approximately through the spring base at which the bias by the drive mechanism is provided and through the cross-section of the bending beam located opposite the spring base in a circumferential direction.

25. Crimping pliers of claim 12 , further comprising a second spring element which provides a contact force of the roller at the guiding part.

26. Crimping pliers of claim 25 , wherein one spring base of the second spring element biases the spring element.