Introduction to the basic knowledge of wire drawing dies

       The reason for the ring groove: it is due to the resistance of the metal wire that enters the die hole when the cross section changes, and the periodic pressure generated by the vibration of the metal wire during the stretching process, which leads to the fatigue failure of the wire die.



The appearance of the die ring groove aggravates the wear of the die hole. Because after the ring groove appears in the die hole of the drawing die, the small particles of core material peeled off due to loosening on the ring groove grind the working area and the sizing area like an abrasive. The metal wire entering the die hole will aggravate the wear of the die hole like a die rod. At this time, the friction between the die hole and the metal wire increases, resulting in high temperature, which intensifies the wear process.



Generally speaking, the wear of the drawing die during the drawing process can be divided into three stages. The first is the sharp-point wear stage of the die hole surface, the second is a low and stable rate wear stage, and the third is the high-speed wear stage with the appearance of the wear grooves on the die hole surface.



The influence of drawing conditions on the service life of drawing dies



On the one hand it depends on its quality, on the other hand it also depends on the stretching conditions



(1) Impact of shrinkage rate



In the stretching process, the wire drawing die produces pressure on the metal wire, and the metal wire also produces a back pressure on the wire drawing die wall when it is deformed. The greater the reduction rate used in stretching, the stronger the pressure of the hole wall on the metal wire, and the reaction force generated by the metal wire on the hole wall will increase accordingly. If this force is greater than the tensile capacity of the mold itself, then The drawing die will crack.



(2) The influence of lubricants



In the stretching process, the quality of the lubricant and the sufficient supply of lubricant affect the service life of the drawing die. Lubricant has lubrication, cooling, cleaning and anti-rust effects during the wire drawing process.



(3) The influence of the surface quality of the metal blank



If there is an oxide layer, sand or other impurities on the surface of the metal blank, it will adversely affect the service life of the drawing die. Because the oxide layer on the metal surface is hard and brittle, when the metal blank passes through the die hole, it will cause the die hole of the drawing die to wear quickly and scratch the surface like an abrasive. Therefore, it must be pickled off before stretching; when the blanks are stacked, pay attention to the neatness of the stacking site and avoid contact with sand and other impurities.