Pliers for cutting workpieces

A pliers for cutting workpieces, in particular workpieces made of metal, comprising at least one plier leg (1) and a pressure element (2), which are connected to each other by a rotation point (13), wherein the plier leg (1) forms a jaw (8) for receiving the workpiece. A cutting element (18) with a cutting mouth (19) is associated with the plier leg (1), wherein a bottom of the jaw (8) and a bottom of the cutting mouth (19) are arranged in the vicinity of a rotation point (29) about which the cutting element (18) is rotating in the plier leg (1).

BACKGROUND OF THE INVENTION

The invention relates to a pair of pliers for cutting workpieces, in particular workpieces of metal, said pliers having at least one leg and one pressure element which are connected together by means of a pivot point, wherein the leg of the pliers realizes a jaw of the pliers for receiving the workpiece.

Varied designs of pliers are known and are on the market. The present case is concerned above all with special pliers for cutting workpieces in accident surgery. They are required, for example in orthopedics to nip off wires, nails or screw-type elements. In this case, the prevention of splinters or similar particles of the workpiece during the separating operation is a hygienic necessity to avoid infections. In the case of intraosseous wires in the operative handling of fractures, bone fragments with wires, in the majority of cases with so-called “Kirschner” wires are connected together. Side cutters or similar tools are used to cut off said wires, which, however, also involves the risk of workpiece residues. In addition, considerable forces have to be applied to the pliers in order to cut the corresponding wire.

Such medical or surgical pliers are known, for example, from EP 0 321 884. Using said wire pliers, a wire is pinched-off, which requires considerable force. The same also applies to the pliers as claimed in EP 0 454 615 or DE 43 29 220 A1.

The object of the present invention is, on the one hand, to develop a pair of pliers of the above-mentioned type which is able to be operated with one hand and which does not require a very high level of force to be expended, additionally, however, does not result in any workpiece waste which can remain behind.

SUMMARY OF THE INVENTION

To achieve the object, on the one hand, the leg of the pliers has associated therewith a cutting element with a cutting jaw, wherein a bottom of the jaw of the pliers and a bottom of the cutting jaw are arranged in the vicinity of a pivot point about which the cutting element rotates in the leg of the pliers.

As a result, the wire is not pinched-off, but is actually cut. The cutting element is rotated about the pivot point and at the same time cuts into the workpiece by way of a cutting edge such that said workpiece is actually cut off once the rotation has been completed. This avoids, on the one hand, splinters or the like being created and, on the other hand, reduces the force expended.

Independent protection is additionally sought for the leg of the pliers having associated therewith a cutting element with a cutting jaw, wherein the contours of the jaw of the pliers and of the cutting jaw are matched to one another and the cutting element rotates in a roller cage in the leg of the pliers.

The advantage of this is that there is controlled interaction between the jaw of the pliers and the cutting jaw. The cutting element is held over a large part of its periphery by the roller cage and is guided in a secured manner about a pivot point during the rotation.

In addition, protection is sought independently for the leg of the pliers to have associated therewith a cutting element with a cutting jaw and the cutting element to be arranged by means of a latching device so as to be rotatable about a pivot point in relation to the leg of the pliers.

Said latching device is particularly important. The necessary force expended is reduced considerably by its actuation. The actuation of the latching device is also not effected in a continuous manner, but in a preferred manner by means of quasi pumping the leg of the pliers or the pressure element in relation to the leg of the pliers.

In a preferred exemplary embodiment, the cutting element is to have a latching toothing located opposite the cutting jaw. Said latching toothing interacts with a toothed strip of a pressure piece, said pressure piece being actuated by the pressure element. To this end, the pressure piece is supported by way of a round piece in a depression in the pressure element. If the pressure element is actuated, the pressure piece with the toothed strip, which engages in the latching toothing of the cutting element, entrains said cutting element and rotates it about the pivot point. As a result, a necessary expending of force is minimized.

So that the pressure piece or the toothed strip remain engaged with the latching toothing, the pressure piece is to have associated therewith another corresponding force storing means which presses onto the pressure piece in such a manner that the toothed strip engages with the latching toothing.

In order to make possible an above-mentioned pumping, that is to say resetting the pressure piece on the latching toothing, another fixing means is to be provided which holds the cutting element in the position of rotation already achieved when the pressure piece is reset. To this end, the fixing means also has a latching strip which engages in the latching toothing of the cutting element. In a simple exemplary embodiment, the fixing means is arranged so as to be displaceable in the toothed leg.

In a preferred manner, the pressure element is realized in the manner of a leg and has a pivot-joint-like connection to the leg of the pliers. To this end, a pivot pin which sits in a pivot depression in the leg of the pliers is provided on the pressure element.

So that a forcing apart of the leg of the pliers and the pressure element is improved, a corresponding force storing means is to be provided between said leg of the pliers and said pressure element. In this case, this can be a spring-mounted bolt.

DETAILED DESCRIPTION

A pair of pliers P as claimed in the invention for cutting workpieces (not shown in any detail) has a leg1of the pliers and a leg-like pressure element2which is associated with the leg1of the pliers. The leg1of the pliers is supported in the closed position against the pressure element2by means of a stop3. It is possible for the stop3to be realized in an elastic manner in this case.

A cover4, which conceals the essential functional elements of the pliers P, can be seen in the front region of the leg1of the pliers. The cover4, in this case, is connected to the leg1of the pliers by means of three screw bolts5.1to5.3. The screw bolts5.1to5.3engage in the threaded bores6.1to6.3of the leg1of the pliers, as is shown inFIG. 2.

In addition, the cover4frames a jaw of the pliers8, which is realized by the leg1of the pliers, by means of a recess7.

It can also be seen inFIG. 2that a guide channel9and a blind hole10are provided in the leg1of the pliers. In addition, receiving means11and12are realized. The receiving means11serves for the bearing arrangement of a stop (to be described later), the receiving means12serves for the bearing arrangement of a pivot pin13(seeFIG. 3), by way of which the pressure element2sits in a pivot depression14in the leg1of the pliers. Along with said pivot pin13, a depression15for receiving a round piece of a pressure piece (to be described later) is realized in the pressure element2, according toFIG. 3. A further blind hole16is open toward said depression15.

A guide pin17, which projects from a cutting element18according toFIGS. 5 and 6, engages in the above-mentioned guide channel9. Said cutting element18has a cutting jaw19the contours of which imitate the jaw8of the pliers. A latching toothing20is provided on the cutting element18opposite the cutting jaw19.

The above-mentioned pressure piece21, which is supported in the depression15of the pressure element2by means of a round piece22, is shown inFIGS. 7 and 8. Said pressure piece21has a toothed strip23. A fixing means24is shown inFIGS. 9 and 10. Said fixing means24has a latching strip25and a draw hook26which is located opposite said latching strip. A stop cam27is also provided in the vicinity of the latching strip25.

The interaction between the individual components can be seen in particular inFIG. 11. The most important point in this case is that the cutting element18in the front region of the leg1of the pliers is inserted into a roller cage28and rotates in said roller cage28. Said rotation is effected about a pivot point19, a bottom of the jaw8of the pliers or of the cutting jaw19being arranged very close to said pivot point29.

It can also be seen, moreover, that the cutting element18engages by way of its guide pin17into the guide channel9and is guided in said guide channel9in a radius about the pivot point19. In addition, the cutting element18impacts against a stop30which is inserted into the receiving means11.

The pressure element2sits with its pivot pin13in the pivot depression14and can be moved to a limited extent in relation to the leg1of the pliers. The pressure piece21is mounted in the depression15by means of the round piece22and is supported in the blind hole16by means of a helical spring31. The toothed strip23of the pressure piece21, in this case, interacts with the latching toothing20of the cutting element18.

The fixing means24is inserted into a guide channel32in the leg1of the pliers and is mounted in said guide channel32so as to be displaceable. Its latching strip25, in this case, covers at least in part the toothed strip23of the pressure piece21. The stop cam27has the effect of not allowing the fixing means24to deflect rearward in an unwanted manner.

In addition,FIG. 11indicates a bolt33which engages in the blind hole10. Said bolt33can be spring-mounted such that the pressure element2is supported in a spring-mounted manner in relation to the leg1of the pliers.

The method of operation of the present invention is as follows:

For cutting a workpiece (not shown in any detail), said workpiece is inserted into the jaw of the pliers or the cutting jaw8/19. The cutting element18, in this case, is situated in the start position shown inFIG. 11such that the jaw8/19is open as extensively as possible. The leg1of the pliers and the pressure element2are forced apart such that the toothed strip23of the pressure piece21engages the latching toothing20of the cutting element18by way of as large a number of teeth as possible. Said engagement is supported by pressure from the helical spring31.

The pressure element2is then moved toward the leg1of the pliers, the pressure piece21entraining the cutting element18such that said cutting element, guided by the guide pin17, rotates about the pivot point19in the guide channel9and in the roller cage28. In this case, the inside clearance of the jaw of the pliers or of the cutting jaw8/19is reduced such that the cutting element18cuts into the workpiece. At the same time, the latching toothing20of the cutting element18runs down the latching strip25of the fixing means24and is held by said fixing means24, when, for recovering, the pressure element2is then moved away from the leg1of the pliers again such that the toothed strip23of the pressure piece21is able to move along the latching toothing20and enters into a new region of said latching toothing20.

The pressure element2can now be moved once again against the leg1of the pliers, the pressure piece21by means of the latching connection with the cutting element18entraining said cutting element and rotating about the pivot point29. This occurs until the work piece has been cut through.