Manufacturing analysis of the part, страница 4

The straight-through cutting tool with the tips produced from the hard alloy is selected according to the GOST 18878-73 [10, p.123, table.13] (ref. fig.2.3).

fig. 2.3

The geometric characteristics are filled in the table #2.4.

Table #2.4

Cutter	h, mm	b, mm	L, mm	n, mm	l, mm	R, mm	φ	φ 1
The straight-through cutter Т5К10 GOST 18887-73	25	16	140	9	12	1.0	60	45

2.7.3 The calculation of cutting process parameters

Calculation of the cutting process for surface # 8 is the following:

The nominal allowance for machining according table #2.2 is following

,  so  .

The feed will be chosen with the help of diagram 14 [10, p.268]. It depends on the required roughness of machining and the radius of the cutter top. This surface is performed with Rz = 80 and radius R = 1mm, thus the feed is equal to S = 0,36 mm/rev.

The feed is more than 0.2, so the cutting velocity will be calculated as following:

,                                    (2.11)

where T=60 min; t= 1.275 mm; =650

К_V=К_MV*К_RV*К_TV*К_φV             (К_φV – the coefficient that shows the influence of cutter parameters [10,p.271,table.18]).

The correction factor К_MV keeps in mind the influence of physical and mechanical material properties К_MV=0.5

According to the table #5 [10,p.263] the correction factor К_RV was defined. This factor takes into account the influence of a blank surface condition. This surface has already been machined, so К_RV=1.

The correction factor К_TV keep in mind the influence of the cutting tool material, so К_TV =1 because the machining is performed by the cutter that are produced from the hard alloy.

The correction factor К_φV – the coefficient that shows the influence of cutter parameters [10,p.271,table.18]), К_φV =1

Thus К_V=0.5*1*1*1=0.5.

The force that exists when the cutting is performed can be calculated by the following formula:

                                 (2.12)

Thus,                    

The torsion moment is calculated by the following formula:

                                                         (2.13)

 ()

The power of spindle lathe is calculated by the following formula:

                                                        (2.14)

 ()

Let’s calculate of frequency rotation of lathe spindle by the following formula:

                                                           (2.15)

2.7.4 Selection of machine

The semiautomatic, screw-cutting lathe 16B16A is chosen for this operation. It is because we have small scale production.

The technical characteristic [10, p.13, table.7]:

·  The rotational frequency spindle is 20; 25; 31; 39; 48; 61; 76;95; 119; 149; 186;232; 291; 363; 454; 568; 710; 888; 1110; 1387; 1734 rev/min;

·  Longitudinal feed tool box is 0.01-0.7 mm/rev;

·  Transversal feed tool box is 0.005-0.35;

·  The power of electric motor transmission is 2.8 kW.

The part is fixed with the help of three-jaw chuck.

The rotational frequency of lathe spindle  is selected in the lathe passport and the actual feed is adopted S = 0.33 mm/rev. If we have the other value of rotational frequency we are to recalculate, , .

So the actual cutting velocity is defined by the following formula:

                                        (2.16)

The force that exists when the cutting is performed by the following formula: