Manufacturing analysis of the part, страница 3

,                                                  (2.3)

,                                                 (2.4)

,                                                     (2.5)

The required values of R_z, h are found in hand-books and specified by production engineer according to the sequence of manufacturing steps. The value of calculated diameters can be corrected according to the accuracy of definite manufacturing step.

Minimal and maximal values of machining tolerance are calculated from:

,                                      (2.6)

,                                 (2.7)

Calculation formulas for holes are derived in the similar manner.

All calculations for diameters are indicated in the table 2.2

2.5 Dimensional analysis of manufacturing process

When planning the manufacturing processes, the allowances and operation dimensions are calculated. It is especially important for linear dimensions. Dimensional analysis of manufacturing process consist of three stages:

1.  Development of dimensional diagram of manufacturing process;

2.  Development of manufacturing dimensional chains;

3.  Solution of manufacturing dimensional equations.

2.6 Manufacturing dimensional chains development and its solution

Development of manufacturing dimensional chains for each manufacturing step is shown on the drawing applied to the explanatory note .

The solution to the manufacturing dimensional chains, when closing link is a design dimension, is calculated with the help of the following formula.

,                     (2.8)

were S_j-increasing constituent links;

S_q-decreasing constituent links.

In this case the general  formula is decomposed in three linear equations with one unknown:

- nominal value of dimension;

- upper limit of nominal dimension;

, - lower limit of nominal dimension.

Upper and lower limits are calculated according to the cross-wise diagram with paying attention to the signs of limits of constituent dimensions.

For solution of manufacturing dimensional chains, when closing link is an operation allowance, the initial equation is rearranged relative to the z_min:

,                                             (2.9)

where S_{j min}- minimal limit values of increasing constituent links;

S_{q max}- maximal limit values of decreasing constituent links.

For determination of allowance and its limits the initial equation of dimension chain is set up with writing of limits of all constituent links;

                                               (2.10)

It is decomposed in three linear equations with one unknown:

- nominal value of allowance;

- upper limit of allowance value;

, - lower limit of allowance value.

Upper and lower limits are calculated according to the cross-wise diagram with paying attention to the signs of limits of constituent dimensions.

All calculations are shown in the Table # 2.3

2.7 Planning of turning operation

Planning of the turning operation for surface # 8 that is machined in operation # 020 was submitted in this para.

Fig. 2.2

During this operation the rough turning is performed for surface # 8, so we have Ø 33.05 h12_(-0.250), Rz=80 ;

The maximal value of allowance is defined from the table # 2.2

2.7.2 Selection of a cutting tool.

Thus, in this operation we have rough turning and to perform it we use the table 3 [10, p.116]. According this table we should use as a cutting tool semi carbide alloy T5T10 for cutting the carbon steel.