Cold drawing machine is a type of drawbench that can be used to make long rods, bars and wires that require precision and strict tolerances. This is a process that can be performed on non-ferrous and ferrous metals.
The process begins with the submerging of raw steel in a liquid lubricant, which helps the steel bars to pass more easily through the dies. The lead ends of the steel are then swaged, which reduces their size. This allows them to travel through the die more easily and prevents the steel from sticking to the die.
Various types of dies are then used to perform the actual drawing. The process involves forcing the lead ends of the steel through the dies until it reaches the desired length and width. Depending on the desired dimensions, multiple passes may be required.
After each pass, the lead ends are re-submerged in lubricant and pulled again through the die. This process is repeated until the desired diameter and wall thickness is reached. Then, the resulting rods are annealed to harden them and improve their strength and ductility.
In order to determine the energy-power parameters of the drawing process, mathematical modeling can be applied. Various simulation packages, including well-known programs such as QForm and ABAQUS, are available to help determine the forces and power that need to be exerted on the drawbench in order to achieve the desired result.
Various factors can influence the performance of a drawing machine, such as the mechanical properties of the metal being drawn, its tendency to harden during cold deformation, and the conditions for injecting technological lubricant into the deformation zone. The calculation of these parameters is complex and requires an understanding of the mechanics of the drawing process.
The determining factor in a successful drawing schedule is the ratio of the wall reduction to the diameter reduction. A high ratio tends to iron, or smooth, the inner diameter surface of the tube and a low one tends to roughen it. The drawing schedule should be designed to achieve a Q value of 2 or higher, which is an expression of this ratio.