Structure Design of Machinized Parts

The quality and cost of machining have a great influence on the quality and cost of mechanical parts and even the whole machine. Therefore, in the design process, it is necessary to consider the mechanical processing technology.
Especially for some special mechanical parts, the manufacturing process is often very special, and special attention should be paid to the design. Whether a part can be manufactured may become a decisive factor in whether a design scheme can be adopted. Therefore, the following issues need to be paid attention to when designing the structure of these machined parts.

1. Material-saving part structure design

Pay attention to reduce the size of the blank, the flange is made of round steel directly, such as the design of the maximum diameter of 100mm to use 105mm or 110mm round steel processing. If the maximum diameter of 98mm is designed, it can be processed with 100mm steel, which can save a lot of steel.

2. Structural design to reduce machining workload

(1) to take into account the impact of casting error

The error of casting parts is relatively large, and it needs to be fully considered when designing the machining surface of the casting. For example, the bearing end cover is matched with the boss on the box body, but the position of the boss on the box body is difficult to be very accurate. If the diameter of the end cap flange and the boss are designed to be exactly equal, the end cap will often protrude beyond the boss due to the influence of casting errors. Therefore, the diameter of the casting boss should be larger.

(2) Different machining accuracy surfaces should be separated

When the two surface roughness requirements are different, there should be a clear dividing line between the two surfaces. This is not only convenient processing, and beautiful shape.

3. Structural design to reduce manual processing or supplementary processing

(1) Use plane grinding instead of manual grinding guide rail

The guide rail of the universal tool microscope for large-scale optical metrology instruments was originally designed as a circular guide rail for manual grinding, but it was later modified to a flat V guide rail, which was processed with a surface grinder, and the productivity was greatly improved.

(2) Use plane grinding or fine planing instead of scraping the sub-box surface of the reduction gearbox.

The sub-box surface of the split reduction gearbox requires high flatness. Originally, some production units used manual scraping and grinding, with heavy workload and low productivity. Later, they were mostly changed to surface grinding machines for processing live precision planers.

4. Simplify the shape and requirements of the processed surface

(1) Need to avoid non-circular parts of the mouth fit

There is a flange on the surface of the box part to match it. In order to make the matching cover accurate positioning, in addition to fixing with screws, the design has a stop fit, the fit hole should be circular, not rectangular, square, oval and other shapes.

(2) Chamfer of parts with complex shapes

It is difficult to chamfer parts with complex shapes. Such as oval and other complex shapes, it is difficult to chamfer by mechanical processing method, chamfer by manual method, it is difficult to ensure the quality of processing.

5. Structure design of parts for easy clamping and measurement

Avoid parts that cannot be clamped, mechanical parts need to be clamped on the machine tool during processing, so mechanical parts need to be easily clamped. In addition, the clamping parts should have enough supporting force to ensure that the parts will not shake under the action of cutting force. Therefore, the parts have sufficient rigidity to avoid clamping deformation.

6, to avoid tool cutting work in adverse conditions

The tool is easy to enter or exit the machining surface. When the tool enters or exits the machining surface, it requires a certain movement space. Sufficient clearance should be reserved when designing.

7. Correctly handle the structure of shaft and hole (inner and outer surface)

Complex machining surface should be designed on the outer surface rather than on the inner surface, and the machining of shaft parts is easier than that of holes. Therefore, when two shafts and hole-shaped parts are matched together, and there are some more complicated structures in between them, it is often better to design these structures on the shaft than on the inner surface of the hole.