Vertical packaging machine with device for the application of a system of opening and closing the packaging

An assembly of a vertical packaging machine and a device for an application of a system of opening and closing the packaging or zip formed by two overlapping elements which can be removably engaged, the vertical packaging machine comprising a framework supporting in succession a feeder of wrapping for the packaging, said wrapping comprising equidistant notches, a forming tube and a welding unit for welding transverse edges of formed wrapping, and the device for applying the system of opening and closing comprising a first welding unit upstream of the forming tube for a first phase of welding of a zip fed transversely to a direction of forward movement of the wrapping and a second welding unit downstream of the forming tube for a final phase of welding of the zip, wherein said device, handled by a programmable controller, also comprises, upstream of the forming tube, a carriage slidingly supported by the framework of the machine in the direction of forward movement of the wrapping to be formed and in turn supporting said first welding unit, and a photo-electric cell attached to the carriage to read the equidistant notches on the wrapper, means for moving said carriage in relation to the wrapping starting from a selected reference position on the framework of the machine, until reaching a position of reading of the notch by the photoelectric cell for a first welding of the zip, and means for positioning the zip on the wrapping in the position selected for the first welding of the zip supported by said carriage.