Tensioning device of BOPP (biaxially-oriented polypropylene) film unwinding brake device of packaging machine

The utility model discloses a tensioning device of a BOPP (biaxially-oriented polypropylene) film unrolling brake device of a packaging machine, which comprises a lower fixing support, a lower pressing plate, a device support, a nut and a compression spring, the lower pressing plate is connected with the lower fixing support through a bolt to clamp a brake belt, and the device support is connected with the lower fixing support through a nut. The lower fixing support comprises a lower fixing support body and a screw arranged on the lower fixing support body, one end of the screw penetrates through and extends out of the device support and is locked through a bolt, and the portion, between the lower fixing support body and the device support, of the screw is sleeved with the compression spring. The service life of the packaging machine BOPP film unrolling brake device manufactured through the tensioning device is 2-3 times that of an original brake device, and the maintenance and part replacement cost of the br