EP2611581B1 - Cutting pliers - Google Patents

Description

The invention relates to a cutting pliers such as a center cutter or a side cutter, with a hinge portion, wherein on one side of the hinge portion pliers handles are formed and on the other side of the hinge portion a free end of the pliers forming, oppositely directed cutting having jaws, further the cutting up are continuously formed and hardened in a tip-side free end portion of the jaws.

Such pliers have already become known in various embodiments. It is for example on the DE 88 03 016 U1 . EP 331 927A1 and WO 2006/108804 directed.

Although the known pliers have proven to be very largely, it has been observed that it sometimes comes to a cancel of the cutting edges at the end. This is attributed to the fact that upon cutting action with the free end portions of the cutting edges on very hard wires, a force is exerted on the cutting edges, which can lead to breakage in these end regions, in particular if they are comparatively very thin or tapered ,

Starting from the illustrated prior art, the invention is concerned with the task of pliers as described above in such a way that a breaking off of a cutting edge in an end region does not occur as possible.

A possible solution to the problem is given according to a first idea of the invention in an object, which in particular has the features that the cutting edges have a lower hardness in the end regions than in adjoining joint region-side sections. According to the invention, it has been recognized that a different hardening of the blades over their length, in such a way that the cutting edge portions in the free end regions have a lower hardness, lead to a more favorable behavior. At a high stress of the cutting about by acting on a highly hardened object such as a highly hardened wire, it is no longer in the end areas to cancel the cutting. Although it can occur a bending of the cutting. And a deflection to the outside. However, this can be accepted rather than a cancel.

Further features of the invention are described below, also in the figure description and in the drawing, often in their preferred assignment to the already explained claim concept or illustrated, but they can also be assigned to only one or more individual features described here or are represented graphically or independently or in another overall context of importance.

Thus, it is preferable that the hardness of the cutters in the end portions is 3 to 7% lower than in remaining portions of the cutters. Surprisingly, it has been found that a comparatively small difference in hardness already leads to a desired effect. This is also attributed to the fact that the formation of the lower hardness, which is preferably limited by a customary, but lengthwise, with regard to an overall length of the cutting edge, limited tempering process (preferably is a second tempering process, see below) on the area of the free end areas, also takes place that the cutting edges in the end areas supporting jaw material is reduced in hardness, so that the cutting at a corresponding Overuse caused by plastic deformation can escape.

It is furthermore preferred that the hardness of the cutting edges in the adjoining joint region-side section is set between 60 and 66 HRC.

On the other hand, the hardness in the tip-side end regions is preferably set in the range between 58 and 62 HRC.

In terms of production, preference is given to proceeding in such a way that the cutters are first of all tempered in the usual way. And to a hardness as it should ultimately be given in the remaining range of cutting, so to a hardness in the range between 60 and 66 HRC. For this purpose, in detail, for example, inductive, carried out a conventional heating of the cutting, then quenched and tempered. Then, the free end portions of the cutting are subjected to a further annealing process. This - usually second - tempering process can be carried out, for example, with a well-controlled laser heating with respect to the influence zone or by inductive heating.

The end area of the cutting edges is limited to 1/4 or less of the total length of the cutting edges. At least, however, a length corresponding to about 1/20 of the total length or more is preferably formed with said lower hardness. In absolute terms, a length range of 2 to 5 mm is preferred.

With regard to the lower hardness, a reduction relative to the initially set, resulting after the tempering process hardness of 3 to 7%, more preferably 4.5 to 5.5 or concrete 5% is relatively preferred.

Incidentally, it is also preferred that said hardening formation is provided, in particular, in the case of pliers which are slim and elongated in the region of the jaws. A measure of such a slim configuration can be given by the fact that a tip-side length portion of the jaws, which has or falls below a certain total width of the closed jaws, relative to a total length of the cutting edges is relatively large. For example, 1/10 or more of the total length is when said total width is 1/4 to 2/3, preferably about 1/3 of the width of the jaws in the joint area start of the cutting. In this case, the width is preferably measured perpendicular to a pivoting plane of the forceps limbs and center plane extending centrally between the cutting edges in the closed state.

With regard to the ranges and ratios mentioned, all intermediate values, in particular in 1/100 length increments of the relative lengths, or 1/10 increments (1/10 mm) of the absolute values or in 1/10% increments, are also given Percentages included in the disclosure. On the one hand in order to narrow down the mentioned range boundaries from below and / or from above, but on the other hand also to include more singular values from the mentioned area in the revelation.

Fig. 1

eine Draufsicht auf eine übliche Schneidzange im geschlossenen Zustand;

Fig. 2

eine Herausvergrößerung der Zangenbacken der Schneidzange gemäß Fig. 1;

Fig. 3

eine Darstellung gemäß Fig. 2 bei einer relativ stumpfen Zangenkopfform.

In the following, the invention will be explained further with reference to the attached drawing, which, however, represents only one exemplary embodiment, in which:

Fig. 1

a plan view of a conventional cutting pliers in the closed state;

Fig. 2

an enlargement of the jaws of the cutting pliers according to Fig. 1 ;

Fig. 3

a representation according to Fig. 2 in a relatively blunt pliers head shape.

Shown and described is a pair of pliers 1 with two pliers legs 2, 3, which are connected to each other in a hinge region 4 for pivoting. On the working area side of the joint region 4, pliers jaws 5, 6 are formed, which have cutting edges 7, 8 facing each other.

The cutting edges 7, 8 are starting from a joint area-side beginning, see baseline G in Fig. 2 , running through to a tip end E and straight running in the embodiment.

The blades are hardened. And indeed, as in Fig. 2 Due to the smaller material thickness in the area of the pliers tip 11, an extension of the hardening area curve results in the area of the plier tips, namely basically corresponding to the outwardly diverging areas 9a and 10a.

Since the pliers tips have been subjected to a second tempering process after the compensation has been carried out, specifically in the tip end region the cutting results, for example, according to the illustrated line 12, as a boundary line, a different, namely lower hardening, on the tip side. In the tip-side end region 13 of the forceps jaws 5, 6, the cutting edges 7, 8 are relatively soft in comparison to the adjoining joint region of the cutting edges 7, 8 extending to the base line G. Since the hardening has a transition, the extent is the selectively set lower curing to a value in the example, said range of 58 to 62 HRC approximately from the line s starting up to the end E of the cutting 7, 8 given. In the area between the lines s and 12 is a transition to the basically set according to the first tempering hardness of the cutting, so given a hardness in the range of 60 to 66 HRC.

Not only in the area of the cutting edges 7, 8 itself, a comparatively soft adjustment of the material is given, but also in the associated region of the jaws 5, 6. Top of the line 12 of the jaws 5, 6, the jaws are also transverse to a median plane MM, the perpendicular to a pivot plane in which the forceps arms are to pivot, centrally with respect to the cutting 7, 8, adjusted correspondingly softer. This softer setting may extend immediately or very soon, starting from the line 12 to the end E, over the respective overall width of a pliers jaw.

Overstress in the area of the point of the tongs, for instance by machining a very hard object such as a hard wire, may lead to a deflection of the edges corresponding to the lines 14 and 15 in the region of the point of the tongs (in this case exaggerated). Canceling the pliers tips but is largely avoided.

The specific starting process in the tip-side end region of the cutting edges can be achieved, for example, by laser application.

In the Fig. 2 illustrated jaws 5, 6 are also comparatively slim and elongated. This can be stated, for example, in that a tip-side longitudinal section 1, in which a total width b of the closed pliers legs 5, 6 is equal to or smaller than 1/3 of the total width B in a joint-area-side end of the blades, seen in the exemplary embodiment measured from the baseline G from , wherein the width b, B is measured perpendicular to the median plane M, 1/10 or more of the total length L of the blades 7, 8. An upper limit for this may, for example, be 0.8 of the total length. Also in this regard, all intermediate values, also in particular in 1/100 steps, on the one hand to delineate the areas mentioned from below and / or above on the other hand but also to represent singular values in the areas, are hereby included in the disclosure.

In the Fig. 3 pliers jaws shown, however, are relatively shorter and wider compared to the jaws of the representation according to Fig. 2 , Even with such jaws and related cutting the illustrated different hardness can be provided.

Claims (5)

1. Cutting pliers (1), such as centre cutters or side cutters, having an articulated region (4), pliers handles (2, 3) being formed on one side of the articulated region (4) and pliers jaws (5, 6), comprising cutting edges (7, 8) which are oriented towards one another and form a free end of the pliers (1), being formed on the other side of the articulated region (4), the cutting edges (7, 8) also being hardened and formed in a single piece as far as a tip-side end region of the pliers jaws (5, 6), characterised in that the cutting edges (7, 8) are formed having a lower degree of hardness in the tip-side end region than in an articulated-region-side portion connected thereto.
2. Cutting pliers according to claim 1, characterised in that the hardness of the cutting edges (7, 8) is 3 to 7 % lower in the tip-side end region.
3. Cutting pliers according to either of the preceding claims, characterised in that the hardness of the cutting edges (7, 8) in the articulated-region-side portion connected thereto is set between 60 and 66 HRC.
4. Cutting pliers according to any of the preceding claims, characterised in that the hardness of the cutting edges (7, 8) in the tip-side end region of the pliers jaws (5, 6) is set between 58 and 62 HRC.
5. Cutting pliers according to any of the preceding claims, characterised in that a tip-side longitudinal portion (I), in which a total width (b) of the closed pliers jaws (5, 6) is equal to or less than a third of the total width (B) in an articulated-region-side end of the cutting edges (7, 8), the width (b, B) being measured in each case perpendicularly to a pivot plane and a central plane (M) extending between the cutting edges (7, 8) being a tenth or more of the total length (L) of the cutting edges (7, 8).

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