In common scissors in which the upper shear blade and the lower shear blade are pivoted to each other in form of a bolt or a rivet, the workpiece is forced in direction of the tip of the scissors because of the wedge-action cutting of the cutting edges. This wedge-type cutting is disadvantageous e.g. during cutting of hair especially of tuft of hair because the cut does not occur at a right angle but slantingly so that splitting of hair has been frequently encountered. Further, this wedge-type cutting renders it rather difficult to create and maintain a straight cut line.
Therefore, it has long been proposed to provide scissors with drawing cut. These scissors, however, did not find application in practice because of their complicated construction. In addition, they are too susceptible to wear and/or proved to be too impractical with regard to handling because of their projecting parts.
From the German patent DE-PS No. 66 126, scissors with drawing cut are known which include a lower shear blade and an upper shear blade pivotally connected to each other by a bolted connection with the bolt projecting in a slot of the upper shear blade. The lower shear blade has a guide coulisse extending slantingly to the longitudinal axis thereof and cooperating with a pin of the upper shear blade so that the latter shifts relative to the lower shear blade during closing of the scissors. The slot of the upper shear blade as well as the guide coulisse are of curved shape. In addition, the upper shear blade supports a pivot about which a rod member is rotatably mounted. At a distance to the pivot, the rod member is also rotatably mounted about the bolt for relieving the bolt and to allow greater tolerances when designing the curved slot which is engaged by the bolt.
Such scissors are disadvantageous because of the considerable width of their shear blades and because the opening angle of the scissors is limited to an angle of about 45.degree..
German patent DE-PS No. 11 794 discloses a scissors whose lower shear blade has a bolt projecting into an oblong hole of the upper shear blade. In addition, the scissors is provided with a joint defined by a toothing in the upper shear blade and several pins spaced on the lower shear blade about an arc of a circle and adapted for engagement in the toothing.
German patent DE-PS No. 44 229 describes a scissors for providing a drawing cut which includes an upper shear blade with a curved slot traversed by a bolt of the lower shear blade and a guideway cooperating with two spaced pins projecting from the lower shear blade so as to guide the scissors during opening and closing thereof.
German publication DE-OS No. 34 07 117 shows a scissors in which the upper shear blade includes an oblong hole parallel to its longitudinal axis for receiving the bolted connection and a further oblong hole extending at an angle to the longitudinal axis of the upper shear blade for guiding a pin inserted in the lower shear blade. This scissors has been proven to be disadvantageous with regard to maintaining tolerances especially when demanding smoothness of the scissors and a wide opening angle of e.g. more than 70.degree..
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