Cold drawing is a process used to reduce the size and shape of metal rods, bars or coils. It involves forcing the lead ends of the steel through a die, which then stretches them to the desired length and width. After the drawing process is complete, annealing is performed to further process and finalize the cold drawn steel bars.
The process of cold drawing uses the same basic principles as hot drawing, except that the raw stock is at or near room temperature. This allows for a more precise and uniform finished product. In addition, it is often more cost effective to draw cold material than to roll the same product from a hotter state.
In the first step, the raw steel bar or rod is submerged in a lubricant. This is done to ensure the steel passes through the die with ease. The lubricant also helps to remove any scale or abrasion from the bar. Metalworking companies may then swage or shave the lead ends of the steel in order to make them smaller and more pointed. This step is called pointing and it allows the steel bar or rod to enter the die more easily.
Once the pointing process is completed, the raw steel rod is then drawn. This entails passing it through a series of dies that are successively smaller in size. It is common for the process to require multiple passes through the dies in order to reach the desired final dimensions. The resulting drawn rod is then annealed to soften it and increase its ductility.
Depending on the specific application, rod and bar drawing may require several different types of dies to produce the desired final products. In these cases, the dies are sized specifically for the material. The diameter of the rod or bar can be reduced by either wrapping the material around a block (wrapped drawing) or by sequentially drawing through a number of dies (multi-pass drawing). In most cases, the final drawn products are annealed before, during and/or between drawing passes in order to achieve optimal mechanical properties and dimensional tolerances.
The energy-power parameters of the drawing process can be determined experimentally or by using mathematical modeling. It is important to know these parameters in order to determine the drawing force and power required. In addition, they are critical in determining the stability and trouble-free operation of the drawing machine. This is especially important for large-scale applications of the cold drawing process. It is also necessary to understand the effect of cold work on the tensile strength and yield strength of the forged or cold-rolled material being drawn. For this reason, a thorough analysis of the process and equipment is essential in optimizing its performance. This is particularly true when the drawing machine is part of a production line. In this case, the performance of each individual machine is dependent on the efficiency and reliability of the other machines in the production line. Cold drawing machine
