The above tensioner manufacturer's mold structure is simple and low cost, but the action of the mold is not safe, the spring set on the mold breaks and the parting surface does not open, while damaging the main action parts of the mold. (2)The movable mold part of the steel belt tensioner mold moves to the rear when it is opened, the swing hook fixed on the middle plate hangs on the stopper on the support plate, and the mold opens from the auxiliary parting surface of the fixed mold part; after the mold opening reaches a certain distance, the swing hook shakes and hooks under the action of the pressure piece, while the middle plate stops moving under the restriction of the stopper screw and opens its main type parting surface, the action of this mold mechanism is solid and reliable It is very inconvenient to manufacture, install, debug and maintain the mold, because the pressure transfer is good and the mold structure is complicated.