Full-floating half axle only transmits torque and does not bear any reaction force and bending moment, so it is widely used in all kinds of cars. 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, which brings convenience to automobile maintenance.
The semi-floating axle 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 various cars with small reaction torque. However, this kind of semi-axle bracket is troublesome to disassemble, and if the semi-axle breaks during driving, it is easy to cause the danger of wheel flying off.
Under the condition of ensuring the product design performance requirements, it is recommended that the axle shaft materials are 40Cr, 42CrMo, 40MnB, 40CrMnMo, 35CrMo, 35CrMnSi, 40CrV and 45 steel, and other materials that can meet the requirements of this standard are also allowed. The material selection of shaft parts is mainly based on the strength, stiffness, wear resistance and manufacturing technology of the shaft, and strives to be economical and reasonable. The commonly used materials for shaft parts are 35, 45 and 50 high-quality carbon steels, of which 45 steel is the most widely used. Ordinary carbon steels such as Q235 and Q255 can also be used for shafts with less or less important loads. Alloy steel can be used for heavy load, limited axial size and weight or some special requirements. For example, 40Cr alloy steel can be used in the workplace with medium precision and high speed, and the material has good comprehensive mechanical properties after quenching and tempering. Cr 15, 65Mn and other alloy steels 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. Low carbon steel such as 20Cr, 20CrMnTi, 20Mn2B or 38CrMoA 1A carburized steel is selected for shaft parts working at high speed and heavy load. After carburizing, quenching or nitriding, these steels not only have high surface hardness, but also greatly improve their central strength, so they have good wear resistance, impact toughness and fatigue strength. Ductile iron and high strength cast iron have good castability and vibration reduction performance, and are often used to manufacture shafts with complex shapes and structures. In particular, the rare earth magnesium nodular cast iron developed in China has the advantages of good impact toughness, friction reduction, vibration reduction and insensitivity to stress concentration, and has been applied to the manufacture of important shaft parts such as automobiles, tractors and machine tools.
The processing steps of the half shaft are as follows:
1, material selection and shearing, and at the same time determine the machining allowance, which is convenient for subsequent processing operations.
2. Forge the axle shaft on the air hammer with the tire mold, and swing the end cover with the pendulum mill.
3. Shot peening the half shaft.
4. Straighten the rod of the blank to ensure verticality. The first time is the straightening of the blank, and the second time is the straightening after heat treatment. Straightening after heat treatment shall ensure that the runout is not greater than 0.08. Blank straightening: two fixed straightening roller devices are used to support the axle shaft, and the transmission connecting device is matched with two protruding parts at the flange end of the axle shaft to drive the axle shaft to rotate. The tailstock center abuts against the rod part of the axle shaft, and the pressure head on the straightener drops, and the axle shaft is straightened under the action of the roller 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 rough lathe the large excircle at any high position between the spline end and the flange end.
5, rough turning small end, rough turning and finish turning with hexagonal turret lathe or copying lathe.
6. The car is big. Flat end face is the key process to improve the productivity of semi-axle production line, and the effect of milling end face by cutting-in method is better.
7, rough turning big end, fine turning big end, fine turning small end.
8. Cold-rolled splines. Center holes at both ends of rolling spline are positioned, and involute spline is rolled. The instrument needed to roll splines is a 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 is 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 relevant 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 located in the initial position between two forming stands, and the teeth at this end are shallow. Only the initial shape of the spline is pressed out of the workpiece, and the two racks move rapidly in the opposite direction to drive the workpiece to rotate, and the metal on the surface of the workpiece is squeezed in step by step. At this time, you can clearly see the dent. At this time, as long as the tooth-shaped parts rotate for a few more weeks, the geometric size and accuracy of the tooth-shaped parts required for quality control can be guaranteed.