The fully floating half axle only transmits torque and does not bear any reaction and bending moment, so it is widely used in various automobiles. The fully floating axle shaft is easy to assemble and disassemble, and the axle shaft can be pulled out only by unscrewing the bolt on the edge of the axle shaft, while the wheel and axle housing can still support the automobile, thus bringing convenience to automobile maintenance.
the semi-floating axle shaft not only transmits torque but also bears all reaction forces and bending moments. Because of its simple supporting structure and low cost, it is widely used in all kinds of cars with small reaction moment. However, this kind of semi-axle support is troublesome to remove, and if the semi-axle breaks during driving, it will easily cause the danger of wheel flying off.
under the condition of ensuring the product design performance requirements, the recommended semi-axle materials are 4Cr, 42CrMo, 4MnB, 4CrMnMo, 35CrMo, 35CrMnSi, 4CrV and No.45 steel, and other materials that can meet the requirements of this standard are also allowed. The selection of materials for shaft parts is mainly based on the strength, stiffness, wear resistance and manufacturing technology of the shaft, and strives to be economical and reasonable. Commonly used materials for shaft parts are 35, 45 and 5 high-quality carbon steels, with 45 steel being the most widely used. Ordinary carbon steels such as Q235 and Q255 can also be used for shafts with less or less important load. Alloy steel can be used for heavy load, limited axial size and weight or some special requirements. For example, 4Cr alloy steel can be used in working places with medium precision and high rotating speed, and the material has good comprehensive mechanical properties after quenching and tempering. Alloy steels such as Cr15 and 65Mn can be used in the case of high precision and poor working conditions. After quenching and tempering, these materials have good wear resistance and fatigue strength. For shaft parts working at high speed and heavy load, low carbon steel such as 2Cr, 2CrMnTi, 2Mn2B or 38CrMoA1A carburized steel are selected. After carburizing, quenching or nitriding, these steels not only have high surface hardness, but also greatly improve their core strength, so they have good wear resistance, impact toughness and fatigue strength. Ductile iron and high-strength cast iron are often used to manufacture shafts with complex shape and structure because of their good casting performance and vibration reduction performance. In particular, the rare earth magnesium nodular cast iron developed in China has the advantages of good impact toughness, friction reduction, vibration absorption and low sensitivity to stress concentration, and has been applied to the manufacture of important shaft parts in automobiles, tractors and machine tools.
Processing steps of semi-axle:
1. Select materials for shearing, and determine the machining allowance at the same time, which is convenient for subsequent processing operations.
2. forging the tire mold for the axle shaft on an air hammer, and swinging the cap with a pendulum mill.
3. carry out shot peening on the half shaft.
4. Straighten the rod of the blank to ensure the verticality. Straighten the blank for the first time and straighten it after heat treatment for the second time. Make sure that the runout is not more than .8. Blank straightening: two fixed straightening roller devices are used to support the half shaft, a transmission connecting device is matched with two protruding parts on the flange end of the half shaft, and the half shaft is driven to rotate, the tailstock center abuts against the rod part of the half shaft, the pressure head on the straightening machine falls, and the half shaft is straightened under the action of the rollers and the pressure head. For straightening after heat treatment, the half shafts are supported at both ends of the fixture, and the fixture can be easily moved from one end to the other, so that the indenter can load and drill the center hole at the small end and roughly turn the large excircle at any high position between the spline end and the flange end.
5, rough turning small end, using hexagonal turret lathe or copying lathe for rough turning and finish turning.
6. The car has a big hole. Flat end face is a key process to improve the productivity of semi-axle production line, and it is better to mill end face by cutting-in method.
7, rough turning big end, fine turning big end, fine turning small end.
8. cold rolled spline. The rolling spline is located with the center holes at both ends, and the involute spline is rolled. The instrument needed for rolling spline is the spline rolling machine. The required measuring tools are micrometer and comprehensive spline gauge. In order to improve the production efficiency and fatigue strength of semi-axle spline, the cold rolling forming process of spline has been widely used at present. This process is a chip-free cold forming process for power transmission parts and gear parts.
This process greatly improves the precision of cold-formed gear parts. In the rolling process, all the related parameters are controlled by positioning, so the determined number of teeth and accurate tooth profile can be guaranteed. Taking rolling as an example, a steel shaft is positioned at the initial position between two forming racks, and the teeth at this end are shallow. Only the initial shape of spline is pressed out on the workpiece, and the two racks move rapidly in opposite directions to drive the workpiece to rotate, and the metal on the surface of the workpiece is squeezed in step by step. At this time, dents can be clearly seen. At this time, as long as the tooth-shaped parts rotate for a few more weeks, the tooth-shaped geometric size and accuracy required by quality control can be guaranteed.