The present invention relates to a cutting device for machines for cutting hides and the like. More specifically, the invention relates to a cutting device that is adapted to be used in machines for cutting hides, leather, materials in sheets or rolls, etc.
As is known, in the sector of machinery for digitally controlled cutting of materials that are extended flat, sheet-like, natural or synthetic, such as hide, leather, materials in sheets or rolls, etc., the cutting tool generally used is mounted in a tool head and is constituted by a blade that is adapted to oscillate vertically at high frequency and is moved in a substantially horizontal plane by way of digital control, on the material along the path of shapes to be cut which are defined or projected on the material.
So as to be deployed correctly on the material to be cut, in order to pass from the cutting of one shape to the next and furthermore in order to execute cutting paths with sharp corner edges, which require the extraction of the blade from the material, it is necessary to bring the oscillating blade vertically out of the material to be cut, in order to then move it conveniently by way of rapid movements, imposed by the digital controller, through the movement axes.
To such end, the cutting device or cutting head must be provided with a system of vertical movement.
The aim is to be able to raise the cutting blade as quickly as possible, especially when executing cutting paths with sharp corner edges (such as for example jagged sections of the outline of the piece), and this is because it enables a reduction in the times for executing the cutting operation.
Currently, the conventional cutting devices have a vertical rise speed of the blade, by way of movement of an oscillating spindle or of an entire tool head, which is limited by the inertia of the moved assembly, by the characteristics of guide systems along which the assembly is moved, and by the dynamic characteristics of the actuators that are adapted to achieve the above mentioned movement.
Techniques are known of returning pneumatic pistons to the stroke limit position, which are based on a spring inserted in the cylinder which pushes the piston into abutment in the absence of a pneumatic supply to the latter.
One solution for the above mentioned cutting devices which is based on such technique thus involves the insertion of a spring propelling the oscillating piston toward the upper stroke limit position, once the pneumatic supply for oscillation of the piston that supports the cutting blade has been deactivated. Such configuration has however a number of drawbacks including the fact that such spring would produce a constant force on the oscillating piston, thus limiting its power during oscillation and penalizing the dynamic characteristics in terms of the ratio of stroke to oscillation frequency.
Furthermore, such spring would require a high capability to withstand extremely high operating frequencies, which is difficult and costly to obtain.