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Design and Machining of Shaft Parts

Writer: Kangding Metal Pubdate:2019-09-09 Source:CNC machining
Description:The shaft parts are designed. The shaft has a circular arc, a process undercut, a thread undercut, a thread, a taper thread, an inner hole and an inner arc. The material is 45 steel. For the multi-purpose axle designed this time, the turning...

The shaft parts are designed. The shaft has a circular arc, a process undercut, a thread undercut, a thread, a taper thread, an inner hole and an inner arc. The material is 45 steel. For the multi-purpose axle designed this time, the turning method of "rough turning-fine turning" will be adopted. That is to say, roughing and finishing the two ends, the outer circle, the thread, the outer taper, the groove, the arc and the drilling hole of the part.

This design is mainly for the analysis of CNC machining process and the processing of specific parts drawings. Firstly, the CNC machining technology is briefly introduced, and then the CNC machining analysis is carried out according to the part drawing.
First, according to the processing steps of the parts and materials, the amount of cutting and other related factors, the tool and the contour of the tool holder and the parts are selected to determine the need for five tools.

Second,  Programming is carried out for part drawings and drawings. This part is a multi-purpose shaft. Its outline is composed of straight line, knife withdrawal groove, arc and thread. In the left end of the part, a cone hole and an inner arc are drilled. In the process of processing, the workpiece needs to drill and then turn the inner arc.

third, When drilling the tool, the reference point should be returned first, and the center of the hole should be taken as the tool point, so that the position of the tool can be corrected. Make the tool position coincide with the tool change point to determine the programming coordinate system and the programming origin, and compile the NC machining program. Finally, use the programming simulation software to simulate and verify the axis parts.

Key words: CNC programming, machining plan, cutting amount, machining program, Shaft Parts

Chapter two  Analysis of machining process of shaft parts
2.1 Shaft Parts Drawing Process Analysis
as the picture shows:
 Shaft Parts Drawing

Axis part structure analysis:
As can be seen from the figure, the part consists of a cylindrical surface, an inner hole, an inner conical surface, an arc surface, a groove, and a thread. The structural shape of the part turning and forming contour is complex and requires two-end machining. The machining accuracy and surface quality requirements of the parts are very high.
The important part of the processing parts of a radial Ф54-0.0390mm cylindrical portion (surface roughness Rɑ = 1.6μm) is connected to the circular arc of R45. Ф40-0.033 0 cylindrical section, inner hole of Ф22+0.021 0 and inner hole of radius R25.
The parts meet the requirements of CNC machining dimension marking, the contour description is clear and complete, the part material is 45 steel, and the blank is ф60mm*110mm.

Programming in small batch production conditions, it is not allowed to use sand cloth and trowel to modify the plane. This is the requirement of high precision plane. Uninjected tolerance size according to GB1804-M, heat treatment, conditioning treatment, HRC25-35, non-injected roughness part smoothness according to Ra6.3, hair embryo size 60mm*110mm.

2.3 Parts Blank and Material Analysis

(1) Analysis of Materials
The cutting force between the tool and the workpiece is larger in the processing of the shaft parts. Cuttability of workpiece materials. Strength, hardness, plasticity, cold cutting and mechanical properties are all related to the material of the workpiece. Therefore, 45 steel is chosen as the material of the shaft parts. The chemical composition of 45 steel contains C 0.42%-0.50%, Si 0.17%-0.37%, Mn 0.50-0.80%, P < 0.035%, S < 0.035%, Cr < 0.25%, N < 0.25%, and Cu < 0.25%. The hardness requirement of 45 steel during cold working is that the indentation diameter of hot rolled steel is not less than 3.9, the Brinell hardness is not less than 241HB, the indentation diameter of annealed steel is not less than 4.4, and the Brinell hardness is not less than 187HB. Mechanical properties of 45 steel: Delta s (> 335 Mpa), delta B (> 600 Mpa, > 40%, Ak (> 47J). Relative cutting tools for 45 steel are 1.0 for carbide, 1.0 for high-speed steel, and the requirements for cutting tools for 45 steel are reasonable. 45 steel has a wide range of uses, mainly used to manufacture steam turbine, compressor, pump moving parts manufacturing gear, shaft piston pin and other parts. According to the above data, it is suitable for the processing of the shaft.

(2) Analysis of blanks
There are three kinds of blanks for axle parts: bar, forging and casting.

Forging:
Suitable for parts with high strength and simple shape. Large parts are usually forged freely because of equipment limitation. Die forging is optional for medium and small parts. The rigid parts with complex shapes should not be forged freely, so they are suitable for the blanks with complex shapes. The mechanical properties of forged billet of steel parts are higher than those of steel bars and castings. According to the structural shape and outline size of the shaft parts, forgings are adopted. The blank of this part should be forged, sawn by bar, forged by die to 60X110mm. The steel is forged to obtain uniform fiber structure, improve its mechanical properties, increase the proportion of parts and blanks, and reduce material consumption.

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