The wire undergoes stretching and deformation in the compression zone, which is a critical area in the drawing die. The compression angle, the angle of the compression zone, is the primary factor governing this zone. The compression angle size can influence the pressure distribution on the die's inner hole and the drawing stress, ultimately dictating the drawn wire's size and mechanical properties.
It is crucial to control the angle of the compression zone during the wire drawing process. If the compression zone angle is too large, it can increase the metal material's deformation rate, resulting in a smaller deformation zone. This generates a lot of heat and makes the lubricating powder ineffective. The wire drawing effect is severely hampered under such conditions. If the compression zone's cooling is not done, it can adversely affect the wire's quality.
Moreover, if the angle of the compression zone is more significant or the compression rate is smaller, the metal material's deformation becomes larger, making it challenging to reach the specified sizing belt area. Additionally, the sizing belt's surface becomes uneven, leading to the ellipse phenomenon if the material is soft. Though the area of the lubrication zone increases, it does not provide better lubrication. Instead, the lubricating powder flows out from the die hole in the reverse direction, causing a vortex effect. The lubricating effect leads to the formation of cracks or scratch marks on the wire's surface.
Thus, the compression zone's angle should not be too significant to avoid losing the lubricating powder's lubricating effect and hampering metal wire's drawing quality.
What if the compression zone angle is too small? This can result in the drawing die generating excessive heat, leading to a failure of the lubrication powder. A smaller angle means that the contact point of the metal material is closer to the top of the compression zone, increasing the deformation area and resulting in higher useless power and heat generation within the drawing die. Additionally, the reduced lubrication area due to a smaller angle leads to a decrease in lubrication effectiveness, affecting the quality of the metal wire being drawn. As the tensile stress increases, the sizing belt diameter also increases, making the occurrence of elliptical deformations more likely, which in turn increases the risk of wire breakage and shrinkage.