sampling of subjects of inquiry and technical baseline for researches
The samples of the right-angled form polished on the one hand a size 10 were exposed to machining? 10? 25 in the core from otozhzhennoj and chilled steel 45. Samples were fixed in opravke so that the polished party was exposed to machining.
Then opravku loaded into the working chamber for some seconds for reception of individual traces of machining. Machining made both on pure spheres, and on the spheres covered with disulphide of molybdenum. After machining traces of individual imprints were photographed on metallographical microscope MIM-8M and indication of diameters of imprints on the instrumental microscope UIM - 21 was spent.Observing the results of measurements resulted in tab. 5.1, it is possible to note, that diameters of imprints decrease with increase in hardness of an investigated steel. Diameters of imprints in spheres with a powder of disulphide of molybdenum more than under the same conditions in pure spheres. The increase in diameters of imprints of the spheres covered with a powder, speaks growth of speed of moving of corpuscles of actuating medium and increase in a kinetic energy of the blow going on a plastic straining.
On the basis of the same results it is installed, that the flowage extent = ~ (where d - diameter of an imprint, D - diameter of a sphere) under equal conditions for otozhzhennoj in pure spheres makes steels of 3,7 % covered - 4,4 %; for chilled steel - 2,9 % in pure spheres, 3,4 % - in the covered spheres.
Table 5.1
Diameters of imprints on a surface of samples
Material of the sample | Hardness | Diameter of an imprint, mm | |
Pure spheres | The covered spheres | ||
Steel 45 (otozh.) | NV 180 | 0,27 - 0,30 | 0,31 - 0,35 |
Steel 45 (temper.) | HRC 30 | 0,20 - 0,22 | 0,25 - 0,27 |
Magnitude of factor of restoration was by sbrasyvanija a sphere on a plate from preliminary measured altitude H. Magnitude of a recoil of a sphere after blow was defined by means of vertical rejki. The restoration factor To paid off by formula Galilee:
Where U - speed of a sphere after blow; V - speed of falling; h - recoil altitude; H - falling altitude.
Magnitude of falling N was accepted at the rate of receptions of speed of falling, equal speed of traffic of corpuscles of actuating medium in the chamber at vibrating machining:
Н=50 Mm (V=0,95 km/s);
N = 100 mm (V=1,4 km/s).
Definition of factor of restoration was spent under three circuit designs presented to tab. 5.2
1) sbrasyvanie a pure sphere on a pure plate;
2) sbrasyvanie a sphere covered with disulphide of molybdenum, on chistujuplitu;
3) sbrasyvanie a sphere covered with disulphide of molybdenum, on a plate too covered with a layer of a powder.
Table 5.2
Definition of factor of restoration
Material, hardness NV | Altitude of falling of sphere N, mm | Full lift h, mm and factor of restoration Ku | |||||
Spheres and plate the pure | The spheres covered МоБ2 | Spheres and the plate, covered MoB: | |||||
H | Ku | H | Ku | H | Ku | ||
Steel 45 | 50 | 10 | 0,45 | 10 | 0,45 | 10 | 0,45 |
(НВ180) | 100 | 20 | 0,45 | 20 | 0,45 | 15 | 0,37 |
Steel 45 | 50 | 20 | 0,63 | 20 | 0,63 | 15 | 0,55 |
(НВ550) | 100 | 40 | 0,63 | 30 | 0,55 | 25 | 0,50 |
The results resulted in tab. 5.2 show, that at small speed of falling the covering molybdenum disulphide only a sphere does not call change of factor of restoration (too small layer of greasing (5 microns) does not possess damping properties).
With increase in speed of falling decrease of factor of restoration is observed. At the big thickness of a covering (are covered both spheres, and a plate) decrease of factor of restoration even is observed at small speed of falling.Conditions at falling of the covered sphere from altitude Н=50 mm on a plate too covered with a layer of a powder of disulphide of molybdenum, are closer to real conditions of vibrating machining and a conversion coating. Therefore the factor of restoration in the presence of a powder and greasing on a surface for chilled steel should be accepted equal 0,50-0,55; for otozhzhennoj - 0,37-0,40.
Hence, in the presence of powder МоБ2 in a zone of contact calculation of key parametres of process is necessary for conducting taking into account a correction index,
Considering quantity of a kinetic energy of the blow going on crushing of corpuscles and consolidation of a layer of greasing - Ку=0,8-0,9.
Numerical value of key parametres of the process, counted taking into account a powder in a zone of contact of actuating medium with a detail surface, is in following limits:
V = 0,2 - 1,3 km/s;
P = 3,0 - 12 kg;
Mouths = 30 - 280 kg/mm2;
Temperature 293 420К
5.2.
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