Forming the head of the bolt adopts cold heading plastic processing. Compared with cutting, the metal fiber (metal wire) is continuous along the shape of the product with no cutting in the middle, thus improving the product strength, especially the excellent mechanical property. Cold heading forming process includes cutting and forming, single-click single-click, double-cold heading and multi-station automatic cold heading. An automatic cold heading machine in several forming die in the stamping, upsetting, extrusion and shrinkage and other multi-station technology. The processing characteristics of the original blanks used in single-station or multi-station automatic cold heading are determined by the bar size of 5-6 meters in material size or the wire diameter of 1900-2000KG, that is, the characteristics of the processing technology Rather than using a pre-cut single piece of stock for cold upsetting, the blank is cut and upset (if necessary) from an automatic cold heading machine itself by bar and wire rod. The blank must be reshaped before the cavity is squeezed. Through plastic surgery can be obtained in line with the requirements of the rough. Before upsetting, shrinking and being squeezed, the blank does not need to be reshaped. Blank cut off, sent to upsetting shaping station. The station can improve the quality of the blank, the next station can reduce the forming force of 15-17%, and can extend the life of the mold, the bolt can be used to reduce the diameter of many times. 1. The use of semi-closed cutting tool cutting blank, the easiest way is to use the sleeve cutting tool; notching angle should be greater than 3 degrees; and when using open cutting tool, the incision angle of up to 5 -7 degrees.
2. Short size blank in the last station from a forming station transfer process should be able to flip 180 degrees, so that the potential of automatic cold heading machine, processing complex structure of fasteners and improve the accuracy of the parts. 3. In each molding station should be equipped with a punch ejector device, die should be equipped with a sleeve-type ejector device. 4. The number of molding stations (excluding the cutting station) should normally reach 3-4 stations (more than 5 in special cases). 5. In the effective use of the period,the structure of the main slider rail and process components can guarantee the punch and die positioning accuracy. 6. In the control of the material baffle must be installed terminal limit switch, we must pay attention to upsetting force control. The roundness of cold dial wire used in the manufacture of high strength fasteners on automatic cold heading machines should be within the diameter tolerances and the more precise fasteners whose wire roundness should be limited to 1 / 2 diameter tolerances, if the wire diameter does not reach the specified size, the upset or parts of the head there will be cracks, or the formation of burrs, if the diameter is smaller than the size of the process, the head will be incomplete , Angular or thick part is not clear. Cold heading can be achieved with the precision molding method with the selection and the process used by the relevant. It also depends on the structural characteristics of the equipment used, the characteristics of the process and its condition, the accuracy of the tooling, the service life and the degree of wear. Forging and extrusion of cold heading high alloy steel, carbide die surface roughness should not be large Ra = 0.2um, the work of such mold surface roughness Ra = 0.025-0.050um, with the highest life expectancy.
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