Single point cutting tools
Many types of metal cutting machines like lathes and shaping machines, use single point metal cutting tools. The cutting action in which metal chips are removed from the body of a metal, is similar to the action of a chisel as shown in Fig 1.1. The pointe
- PDF / 535,715 Bytes
- 6 Pages / 439.37 x 666.142 pts Page_size
- 60 Downloads / 194 Views
15 Single point cutting tools
Many types of metal cutting machines like lathes and shaping machines, use single point metal cutting tools. The cutting action in which metal chips are removed from the body of a metal, is similar to the action of a chisel as shown in Fig 1.1. The pointed part of the tool is a wedge, which presses heavily on the body of the metal, and tears off a chip when the metal moves relative to the tool. For efficient metal cutting, it is absolutely important that the tools are made of the right material, and that the correct cutting angles are ground on the tip of the tool. The values of the cutting angles depend on the type of material being cut. The angles that are important in a lathe cutting tool are the following: Front or top rake angle A, Side rake angle B, Front clearance angle C, Side clearance angle D. Fig 15.1 and Fig 15.2 show the angles, and the formation of chip on a cylindrical piece of metal. The rake angle has the function of aiming the cutting edge of the tool towards the work, and shearing the metal with an upwards, rather than a sideways force. Clearance angles are necessary to ensure, that only the edge of the tool touches the work. If there was no clearance angle, the tool would not cut, but only rub against the work. Fig 15.3 shows a lathe tool with the principal cutting angles. Fig 15.4 shows a complete set of lathe tools, suitable for different cutting operations. Any change in the angles ground on a tool has a marked effect on the amount of heat generated, on tool wear, and on the surface finish of the work. Lubrication and the use of cutting fluids When fast cutting speeds are used, it is usually the practice to pump a small amount of cutting fluid over the cutting edge of the tool. The use of a cutting fluid reduces the heat generated during the cutting process, and thus increases the life of the tool. The cutting fluid also helps to remove chips from the cutting edge of the tool, and improves the surface finish of the object being turned. Water soluble oils are cheap and efficient coolants, and are suitable for the machining of most steel components. Water soluble coolants however, do
A. Jayendran, Englisch für Maschinenbauer © Springer Fachmedien Wiesbaden 1994
89
15 Single point cutting tools
not have very good lubricating properties, and are unsuitable for more complex machining operations, such as gear cutting.
Carbide tipped tools Fast cutting speeds involve considerable metal removal in a minimum of time, and to maintain the accuracy of the parts produced, it is essential that tool wear be kept to a minimum. Carbide tipped tools are almost as hard as diamond, and will maintain a sharp cutting edge under conditions that would cause ordinary tools to burn away. Carbide is the name given to several alloys of carbon and some metals like tungsten, titanium, and tantalum. Carbides are brittle materials, and this makes it necessary to use them only as tips for tools. A carbide tip is usually brazed on to a tool body made of ordinary steel, and then ground to t
Data Loading...
