Improvement of workpieces upsetting on automatic single-impact presses

Abstract

The authors constructed cyclograms in Cartesian coordinates, used the slide of the automatic press machine as the primary actuator, determining the angles of rotation of the flywheel with an error of ±2º. The cyclograms show the sequence of switching on, switching off and idle time of the four movable mechanisms of the press machine: the slider, the knife, the pair of rollers and the ejector. The article contains the calculation of technological processes of cold upsetting of the countersunk rivets, and the rivets with trapezoidal head, as well as different lengths of the rivet shank. Flywheel rotation angles indicate linear movement of the movable mechanisms of the press machine in a proportion relative to the slide working stroke length of 90 mm, which corresponds to the angle z of 180º. The cyclograms of the work of the single-position single-impact cold upsetting of the automatic press machine during rivet heads upsetting into the cavity of the die have been shown in the article. The workpiece must be long enough to be cut off the wire and located ahead of the die in a proper time just as the slide moves to the die to a distance exceeding the lengh of the workpiece.The limit length of the deformable pieces may be increased by the height of the head that is to be upset into the die cavity. The authors found that the angle of the lag after stopping the moving blade must be determined before the butt ends of the punch and the workpiece coincide. Upsetting into the die cavity with the minimum angles of the lag made it possible to increase the maximum length of the stamped workpieces by 6%