Device for assembling nut and bolt by automatically setting torque

The utility model relates to a device for assembling a nut and a bolt by automatically setting torque, belonging to the field of machining technology. The device is provided with a fixture cylinder, a cylinder, a display screen, a servo shaft and a tightening mechanism, which are respectively connected with a programmable logic controller (PLC) cabinet; a fixture provided with the fixture cylinder is arranged on a working platform; the fixture cylinder is provided with a sensor I; a stand column of the working platform is provided with the cylinder; the cylinder is provided with a sensor II; the servo shaft is fixed with the tightening mechanism; and the servo shaft and the tightening mechanism are respectively connected with a piston of the cylinder. According to the device, the fixture cylinder is controlled by the PLC cabinet, so that a product is clamped by the fixture; and meanwhile, the PLC cabinet is used for controlling the rotation of the servo shaft, so that the nut or the bolt can be screwed into the product by the tightening mechanism, and a torque value set by the PLC cabinet can be reached. The whole assembly process is controlled by the PLC cabinet, so that full-automatic screw-in and torque confirmation are achieved. The working efficiency and the product quality assurance capability are greatly improved, so that the device is suitable for assembling of parts on a large scale.