Most metal mechanical parts are machined before they are used for official use. This is the final step before assembling the machine parts. Therefore, the quality and cost of machining has a great impact on the quality and cost of machine parts and the machine as a whole. Therefore, the design process must consider the machining process.
Especially for some special mechanical parts, the manufacturing process is often very special and requires special consideration in the design. The ability to manufacture a part is a decisive factor in the adoption of a design. Therefore, the following issues should be noted when designing the structure of these machined parts:
1. Structural design of parts to save materials
Note that it reduces the blank size. The flange is made directly of round steel. If the maximum diameter of the design is 100 mm, it should be treated with 105 mm or 110 mm round steel. If the maximum diameter of the design is 98mm, it can be processed with 100mm steel, saving a lot of steel.
2. Structural design to reduce the amount of machining
(1) Consider the effect of cast error
The error in the cast part is relatively large and should be taken into consideration when designing the cast surface. For example, the bearing end cover matches the boss of the box body, but it is difficult to position the boss of the box body very accurately. If the diameter of the end cap flange is designed to be exactly equal to the diameter of the convex platform, the effects of casting errors often result in the end cap protruding beyond the convex platform. Therefore, the diameter of the casting boss should be large.
(2) Surfaces with different processing accuracy must be processed individually.
If the two surface roughness requirements are different, there must be a clear boundary between the two surfaces. It is not only easy to process, but also beautiful in shape.
3. Reduce the structural design of manual processing or supplementary processing
(1) Replace manual grinding with surface grinding
The universal tool microscope guideway for large optical measuring instruments was originally designed as a circular guideway used for manual guidance and then changed to a flat V guideway. Processed with a surface grinding machine, productivity has been greatly improved.
(2) Replace the scraper box with a surface grinding machine or fine planer.
The split surface of the split gearbox case must have a high degree of flatness. Some production units use heavy workload and low productivity manual scraping. Later, it was changed to a surface grinding machine for processing live fine planers.
4. Simplify the shape and requirements of the machined surface
(1) It is necessary to avoid non-circular parts with a stop fit.
There is a flange on the surface of the box part to fit it. To ensure the correct position of the cover. In addition to being screwed in, it is designed with a stop fit. Matching holes should be rounded and other shapes such as rectangles, squares and ovals are not suitable.
(2) Must be filled with chamfers of parts with complex shapes
Chamfering parts with complex shapes is difficult. As such an elliptical complex shape, it is difficult to chamfer by hand machining and chamfering, and it is difficult to guarantee the quality of the process.
5. Structural design of parts for easy clamping and measurement
To avoid the structure of parts that cannot be clamped, the machine parts must be clamped to the machine during machining, so the parts must be easily clamped to the machine parts. In addition, clamp parts need sufficient support to prevent them from shaking under the action of cutting forces. Therefore, the part is rigid enough to avoid clamp deformation.
6.To avoid cutting tools under unfavorable conditions
The tool can easily move in and out of the machined surface. A certain amount of moving space is required when the tool moves in and out of the machined surface. The design must maintain sufficient clearance.
7. Correctly handle the shaft and hole structure (inner and outer surfaces)
Complex machined surfaces are designed on the outer surface rather than the inner surface, and shaft parts are easier to machine than holes.
Therefore, if you combine two shafts and hole-shaped parts and there are some more complex structures between them, it is often better to design these structures on the axle rather than on the inner surface of the hole. ..
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