There is developed an equipment for die-less wire cold rolling using 3 shaped rollers that are driven with the help of chain sprocket arrangement. It offers speed of about 20m/sec for copper wire of 3.20mm to +/- 1% accuracy. There are also developed machines to reduce 8-10mm steel wire rod to about 1.5/2mm. However, it will take some time for such equipment to be used in commercial applications as it requires more refinements and development. Till then, Wire Drawing Dies are considered to be the most popular and commonly used equipment by industries across the globe.
Basically, these dies are considered to be the mixture of two dies. The first one has a slightly larger diameter when compared to the second. It also has a lubricant that exits the first die to enter the second one\ at a particular pressure. Hence, it has derived the name ‘pressure die’. It helps with lubricant pick-up along with creation of residual film within the first draft. It preserves this lubricant film, but as subsequent drafts. You can also benefit from using diamond drawing dies.
Rotating die boxes
They are die holders that contain the die within the bronze holder casing. It rotates smoothly along with the die, but in a speed of about 4-48 RPM around the drawn wire. In the final pass are used lower speed boxes to help the wire derive an excellent finish as well as to prevent friction that could otherwise be generated during fast die rotation and high drawing speed. Fast rotating die boxes, for the initial passes are used. This is because, in such passes, drawing speed is found to be much lower. Getting to know about nano dies in details can also help derive benefits from its usage. Rotating die boxes offers the given below benefits:
- Longer die life
- Less wire breakage and uniform die wear
- Ability to generate high accuracy wire and preventing ovality in wire.
Logging onto reputed portals like https://www.szwiredie.com/ will allow you to know the types of wire dies available, their uses and benefits derived.
To draw bar / rectangular wire / square in range of 4-32 mm, you can find adjustable dies having Tungsten Carbine with 4 interlocking pieces. They can be adjusted with the desired size as well as lock them in correct position. Their high regrinding and initial cot is what has made industries to choose cost-effective alternatives like Nano dies.
Die Cooling & its importance
Wire deformation and friction between die and wire tend to generate tremendous heat. But this heat is found to increase with higher reduction and increasing drawing speeds. Temperatures for mild steel rises between 60 and 80 degrees while for carbon wire / draft encountered is 100 to 150 degree Celsius. There are adopted different techniques to dissipate this heat. The wire is then cooled down between the two passes. One technique used successfully to cool the die is using running water. Heat is dissipated at source of generation. Its importance and effectiveness cannot be underestimated for various reasons. It also includes Nano Diamond Coated Dies.