Part machining process

Justification of developed part processing process

The annual production program of the part "bearing bushing" is 200 pieces, which corresponds to the average production.

Preparation - stamping on the 4th class of accuracy, preparation material - srednelegirovanny chrome-nickel steel 12H2N4ASh, hardness of HRC 3342, without preliminary heat treatment.

Based on the working drawing of the part, we determine that the technological process of the part includes 4 stages: draft, finish, final, finish.

In general, the process consists of:

- rough turning and milling of surfaces according to JT12 and JT11;

- finishing turn as per JT10 and JT19;

- rough, finished, medium accuracy according to JT9, JT8;

- fine grinding according to JT6;

- drilling as per JT11;

At the end of the draft stage, some treated surfaces are winded to protect these surfaces from subsequent cementation.

This is followed by cementation of unprotected surfaces of the part to a depth of 0.9-1.1 mm to achieve the required hardness of these surfaces HRC > 59 and thermal treatment - hardening.

To reduce distortions, internal stresses arising after rough treatment are relieved - this is thermal treatment - tempering.

To protect against corrosion, to ensure the lapping properties of the part during assembly at the end of the process, a cadmification operation is provided.

When assigning bases, we use the principle of combining the source and installation bases.

As the installation base, we select the surface of the part that has the greatest extent and regular geometric shape.

If possible, we reduce the range of equipment, cutting and measuring tools used.

We envisage mechanization of machine tools.

Part Processability Analysis

The part "flange" is quite specific: the largest diameter is 210 mm, the linear size is 58.5 mm. The manufacturing process consists of 20 different operations .

All dimensions of the part are standardized according to the normal number series, allowable deviations are assigned according to GOST. The presence of unified elements and part parameters reduces the required range of cutting and measuring tools.

the flange is a body of revolution, which determines the widespread use in the manufacture of the part of turning-screw machines - 1K625, 1K62. Holes are provided in the part, which are made on the vertical drilling machine 2H125. Drilling is performed in conductor with dividing device. Grinding is carried out on flat-grinding, in-grinding and round-grinding machines. A small number of machines are used in the manufacture of the part.

The configuration of the part mainly allows the use of standard machine tools. It was necessary to design special devices only for heat treatment operations, as a result of which the cost of the part increases.

Let's consider the surfaces of the part, to which high requirements of manufacturing accuracy and mutual arrangement are presented:

- The surface of the left end is made according to the 6th accuracy quota with Ra 0.16;

- Non-perpendicular protrusion relative to outer diameter is not more than 0.01 mm;

- End run-out of projection relative to outer diameter is not more than 0.03 mm;

- End run-out of inner left end relative to inner hole is not more than 0.02 mm.