There are many kinds of machine tool parts, which can be divided into: shaft parts, gear parts, machine tool guide rails, etc. according to their structural characteristics, functions and loading characteristics.
Material Selection of Machine Tool Shaft Parts
The machine tool spindle is the most important shaft part in the machine tool. Depending on the type of machine tool, the working conditions of the spindle are also different. According to the size and type of the load on the spindle, it can be roughly divided into four categories:
Lightly loaded spindle. The working load is small, the impact load is not large, and the wear of the journal is not serious, such as the spindle of an ordinary lathe. This kind of shaft is generally made of 45 steel, which is quenched and tempered or normalized, and high-frequency surface quenching is used for parts requiring wear resistance.
Medium load spindle. Moderate loads, severe wear, certain impact loads, such as milling machine spindles. Generally made of alloy quenched and tempered steel, such as 40Cr steel, after quenching and tempering treatment, it is required to carry out surface quenching and strengthening on the wear-resistant parts.
Reload the spindle. The working load is heavy, and the wear and impact are serious, such as the combined machine tool spindle with heavy working load. Generally made of 20CrMnTi steel, after carburizing and quenching.
High precision spindle. The working load of some machine tool spindles is not large, but the precision requirements are very high, and the deformation after heat treatment should be extremely small. There should be very little wear during operation, such as the spindle of a precision boring machine. Generally, it is made of 38CrMoAlA special nitriding steel, and after quenching and tempering treatment, nitriding and dimensional stabilization treatment are carried out. In the past, spindles were almost entirely made of steel, and light and medium-duty spindles have been made of ductile iron.
Selection of gear parts for machine tools
Machine tool gears are divided into three categories according to the working conditions:
Lightly loaded gear. The rotation speed is generally not high, and most of them are made of 45 steel, which have been normalized or quenched and tempered.
Medium load gear. Generally, it is made of 45 steel, after normalizing or quenching and tempering, it will be strengthened by high-frequency surface quenching to improve the bearing capacity and wear resistance of the gear. For large-size gears, it needs to be made of alloy quenched and tempered steel such as 40Cr. Most of the gears in the transmission system and feed system of general machine tools belong to this category.
Heavy duty gear. For some gears with large working loads, especially gears with high operating speed and large impact loads, most of them are made of carburizing steel such as 20Cr and 20CrMnTi. Used after carburizing and quenching. For example: some important transmission gears in the gearbox, etc.
Selection of machine tool rails
The accuracy of the guide rail of the machine tool has a great influence on the accuracy of the entire machine tool. It must be prevented from deformation and wear, so machine tool guide rails are usually made of gray cast iron, such as HT200 and HT350. Gray cast iron has good wear resistance under lubricated conditions, but poor resistance to abrasive wear. In order to improve wear resistance, the surface of the guide rail can be quenched.
Material Selection Analysis of Tractor and Automobile Parts
Selection of Engine and Driveline Parts These two parts include quite a few parts. Among them, there are a large number of gears and various shafts, as well as parts that work at high temperatures, such as intake and exhaust valves, pistons, etc. Their materials are more important, and they are generally selected based on experience in use. For different types of cars and different production plants, the selection of materials for engines and transmission systems is different. The appropriate material should be selected through a large number of calculations and tests according to the specific working conditions of the parts and the actual failure mode.
Material Selection for Reducing Vehicle Weight With the increasing shortage of energy and raw material supply, people’s requirements for energy saving and consumption reduction of vehicles are getting higher and higher. Reducing the self-weight can improve the weight utilization factor of the car, reduce material consumption and fuel consumption, which is of great significance in terms of resource and energy conservation and economic value. The materials selected to reduce self-weight should be lighter than traditional materials and can ensure business performance. For example, if aluminum alloy or magnesium alloy is used instead of cast iron, the weight can be reduced to 1/3 to 1/4 of the original, but its performance will not be affected; new dual-phase steel sheets are used instead of ordinary low-carbon steel sheets to produce automobiles For stamping parts, relatively thin plates can be used to reduce the self-weight, but the strength of the components is not reduced at all; in the body and some less important structural parts, the use of plastic or fiber-reinforced composite materials instead of steel can also reduce the self-weight and reduce energy consumption.