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Some details to pay attention to when machining shaft parts

Shaft parts are a common type of parts, its structure is a rotating body, the length is generally greater than the diameter, in a variety of mechanical equipment has a wide range of use, used to support the transmission parts, transfer torque and bear the load. Shaft parts processing to follow certain rules, you can learn through this article about the specific processing steps and need to pay attention to some of the issues.

First, the basic processing route of shaft parts

The main machining surface of shaft parts is the outer surface and common special-shaped surface, so it should be for various accuracy levels and surface roughness requirements, choose the most suitable processing method. The basic machining routes can be summarized into four.

Firstly, the machining route from rough turning to semi-finishing turning and then to finishing turning, which is also the most important process route chosen for the general common material shaft parts pin outer circle machining.

Secondly, the machining route from rough turning to semi-finishing turning, then to rough grinding, and finally to fine grinding, which is the best choice for ferrous materials and parts with high accuracy requirements, small surface roughness requirements and the need for hardening, because grinding is the most desirable subsequent machining process for them.

The third route is from rough turning to semi-finishing turning, and then to finishing turning and diamond turning. This machining route is specifically used for processing non-ferrous materials, because non-ferrous metals are less hard and easy to block the gaps between sand grains, and it is usually not easy to get the required surface roughness by grinding, and the finishing turning and diamond turning process must be used.

The last processing route is from rough turning to semi-finishing turning, then to rough grinding, finishing grinding, and finally finishing processing. This route is a frequent processing route for ferrous materials that are hardened and require high precision and low surface roughness values.

Second, the pre-processing of shaft parts

Before turning the outer circle of shaft parts, some preparatory processes are carried out, which is the pre-machining process of shaft parts. The most important preparatory process is straightening. This is because workpiece blanks are often bent and deformed during manufacturing, transportation and storage. In order to ensure reliable clamping and uniform distribution of machining allowance, in the cold state, through a variety of presses or straightening machine to straighten.

Third, the positioning reference of shaft parts processing

First of all, the center hole of the workpiece as a positioning reference for processing. Shaft parts processing, the outer surface, tapered hole, threaded surface coaxiality, end face perpendicularity of the axis of rotation is an important reflection of the position accuracy. These surfaces are generally designed with the centerline of the shaft as the reference, with the center hole positioning, in line with the principle of coincidence of the reference. The center hole is not only the positioning reference for turning processing, but also the positioning reference and inspection reference for other processing processes, which is in line with the principle of unification of the reference. When two center holes are used for positioning, it can also maximize the machining of multiple external circles and end faces in one clamping.

Next, the outer circle and the center hole are used as the positioning reference for machining. This method effectively overcomes the disadvantage of poor rigidity of center hole positioning, especially when machining heavier workpieces, where center hole positioning can cause unstable clamping and the cutting amount cannot be too large. By using the outer circle and the center hole as the positioning reference, we do not have to worry about this problem. Rough machining, the use of the outer surface of the shaft and a center hole as a positioning reference method can withstand the larger cutting moment in the processing, is the most common shaft parts of a positioning method.

The third is to use the two outer surfaces as the positioning reference for machining. In the processing of hollow shaft bore, can not use the center hole as a positioning reference, so should use the two external surfaces of the shaft as a positioning reference. When machining the machine tool spindle, the two support journals are often used as the positioning datum, which can effectively ensure the coaxiality requirement of the tapered hole relative to the support journals and eliminate the error caused by the non-coincidence of the datum.

Finally, the tapered plug with a central hole is used as the positioning reference for machining. This method is the most common in the processing of the outer surface of the hollow shaft.

Fourth, the shaft parts clamping

Tapered plug and tapered sleeve mandrel processing must have high processing accuracy, the center hole is not only the positioning benchmark of its own manufacturing, but also the benchmark of the hollow shaft outer finishing, must ensure that the tapered surface of the tapered plug or tapered sleeve mandrel and the center hole have a high coaxiality. Therefore, in the selection of clamping method should pay attention to minimize the number of times to install the taper plug, so as to reduce the repeated installation error of the parts. In actual production, after the taper plug is installed, generally speaking, it will not be removed or replaced in the middle of the process until the process is completed.