What are the characteristics of NC turning process?
Turning is a method of cutting a workpiece on a lathe by using the workpiece to rotate relative to the tool. Turning is the most basic and common cutting method. Most workpieces with revolving surfaces can be machined by turning, such as inner and outer cylindrical surfaces, inner and outer conical surfaces, end faces, grooves, threads and revolving forming surfaces. Common lathes can be divided into horizontal lathes, floor lathes, vertical lathes, turret lathes and copying lathes, and most of them are horizontal lathes.
With the development of modern science and technology, various high-strength and high-hardness engineering materials are more and more used. The traditional turning technology is not competent or can't realize the processing of some high-strength and high-hardness materials at all, but the modern hard turning technology makes it possible, and obtains obvious benefits in production.
Here's a brief introduction to the characteristics of lathe cutting:
1. Introduction of the characteristics of turning
(1) high turning efficiency
Turning has higher efficiency than grinding. Turning often uses large cutting depth and high workpiece rotation speed, and its metal removal rate is usually several times that of grinding. When turning, one clamping can finish a variety of surface machining, while grinding requires multiple installations, so its auxiliary time is short and the position accuracy between machined surfaces is high.
(2) Low equipment investment cost. When the productivity is the same, the investment of lathe is obviously better than that of grinder, and the cost of its auxiliary system is also low. For small batch production, turning does not need special equipment, while for mass production of high-precision parts, it is necessary to use CNC machine tools with good rigidity, high positioning accuracy and repeated positioning accuracy.
(3) Suitable for small batch flexible production. The lathe itself is a flexible processing method with a wide processing range. The lathe is easy to operate and quick to turn and clamp. Compared with grinding, hard turning can better meet the requirements of flexible production.
(4) Hard turning can make the parts obtain good overall machining accuracy.
Most of the heat produced in hard turning is taken away by cutting oil, which will not produce surface burns and cracks like grinding. It has excellent machined surface quality and precise machining roundness, and can ensure high position accuracy between machined surfaces.
Second, the turning tool material and its selection
(1) Coated cemented carbide tool
Coated cemented carbide tool is to coat one or more layers of coatings with good wear resistance on cemented carbide tools with good toughness. The coatings usually play the following two roles: on the one hand, it has much lower thermal conductivity than the tool matrix and workpiece materials, which weakens the thermal action of the tool matrix; On the other hand, it can effectively improve the friction and adhesion in the cutting process and reduce the generation of cutting heat. Compared with cemented carbide tools, coated cemented carbide tools have been greatly improved in strength, hardness and wear resistance
(2) Cutting tools made of ceramic materials
Ceramic cutting tools have the characteristics of high hardness, high strength, good wear resistance, good chemical stability, good anti-bonding performance, low friction coefficient and low price. When in normal use, the durability is extremely high, and the vehicle speed is several times higher than that of cemented carbide. It is especially suitable for high-hardness material processing, finishing and high-speed processing.
(3) Cubic boron nitride cutter
Cubic boron nitride is second only to diamond in hardness and wear resistance, and has excellent high-temperature hardness. Compared with ceramic tools, its heat resistance and chemical stability are slightly worse, but its impact strength and crushing resistance are better. If you don't want to work at the bottom, get rid of the status quo and learn UG programming, you can add QQ group 192963572 to learn CNC machining programming technology. It is widely used in the cutting of hardened steel, pearlite gray cast iron, chilled cast iron and high-temperature alloy. Compared with cemented carbide tools, its cutting speed can even be increased by an order of magnitude.
III. Selection of Cutting Oil
(1) Tool steel tools have poor heat resistance and lose hardness at high temperature, so cutting oil with good cooling performance, low viscosity and good fluidity is required.
(2) When high-speed steel tools are used for high-speed rough cutting, the cutting amount is large and a lot of cutting heat is generated, so cutting oil with good cooling property should be used. If high-speed steel tools are used for medium and low-speed finishing, generally, low-viscosity cutting oil can reduce the friction bond between the tool and the workpiece, inhibit the formation of cutting tumor and improve the machining accuracy.
(3) Cemented carbide tools have higher melting point and hardness, better chemical and thermal stability, and better cutting and wear resistance than high-speed steel tools. Active sulfur cutting oil can be used in general processing. If it is heavy cutting, the cutting temperature is very high, and it is easy to wear the tool very quickly. At this time, inactive sulfurized cutting oil should be selected and the flow rate of cutting oil should be increased to ensure sufficient cooling and lubrication.
(4) Ceramic cutting tools, diamond cutting tools and cubic boron nitride cutting tools all have high hardness and wear resistance. Generally, low viscosity inactive sulfurized cutting oil is used in cutting to ensure the surface smoothness of the machined workpiece.
That is, the characteristics of the turning process are noted above. Reasonable selection of cutting tools and cutting oil products can significantly improve the quality of workpieces.