The utility model relates to a processing device for assembling products, in particular to a device for assembling the fuse. A worktable fixed on a framework is provided with a turnplate mechanism with at least four working positions; rotatable clamping heads extended radially out are arranged on the working positions of the turnplate of the turnplate mechanism. An outer pipe pushing-in mechanism, a threading upper cap welding mechanism, a lower cap welding mechanism, a positioning mechanism, and a material receiving mechanism are arranged on the positions of the worktable corresponding to all the clamping heads on the working positions. Except for the material receiving mechanism, all above mechanisms are driven by cams and transmission rods arranged under the worktable. The outer pipe pushing-in mechanism connects with an outer pipe feeding device, the threading upper cap welding mechanism connects with an upper cap feeding device, and the lower cap welding mechanism connects with a lower cap feeding device. A device which can rotate the clamping heads is arranged on the worktable or the turnplate mechanism, and driving shafts are driven by a motor. The outer pipe feeding device, the upper cap feeding device, the lower cap feeding device, a heating device, and the motor are connected with a power supply controlling device.