Influence of the work parameters on the microhardness of the cold plastic deformed surfaces.

Sarbu, Ionel ; Carausu, Constantin ; Paraschiv, Dragos 等

1. INTRODUCTION

The experimental trials have been done at SC Rulmenji SA Barlad pursuing the influence of the technological elements (the force of deformation, the deformation feed and piece's speed of rotation) on the microhardness of the bearing races of rings on the cold plastic deformed bearings (Wagoner, 2001). The measurements of the microhardness have been done following the diagram in fig. 1 (Pruteanu et al., 2006).

2. EXPERIMENTATION CONDITIONS

2.1. Material and semi-manufactured

We used the special material for the manufacturing of the bearings rings, 100Cr6 and the ring shape forged and hot rolled semi-manufactured.

2.2. Measurement machines and devices

For the plastic deformation of the bearing races of the bearing rings we have used special machines type CRF-120 OR for the ring 6210-10 (external ring) and type CRF-70 IR for the ring 6210-20 (interior ring). For the measurement of the micro hardness we have used the device Akashi MVK-D (Pruteanu et al., 2007).

3. MATHEMATICAL PROCESSING OF THE EXPERIMENTAL RESULTS

For the deduction of the empirical relations and the representation of the working parameters' influences we have used the following functions: F1(x) = a.x + b; F2(x) = a.eb.x; F3(x) = a + b.ln.x; F4(x) = a = b/x; F5(x) = a + b.x + c.x2.

We deducted the coefficient of correlation R, the estimated error, we applied the test F of significance and through comparison we established the most suitable model for the data in the experiment.

After the cold plastic deformation we have done the measurements of micro hardness HV0.5, depending on the working parameters, mentioned in table 1 for the external ring 6210-10. Each time we varied one of the parameters deformation force, F, deformation feed A and rotation speed of the piece V and we maintained constant the other two.

[FIGURE 1 OMITTED]

For exemplification we present the diagram of the empirical modules, the tables with the estimated parameters and the relations of the functions which describe best the variation of the micro-hardness (values of the relations "bold" in table 1), are presented in figures 2, 3 and 4. One can notice that for the external ring the micro-hardness of the bearing races for all the working parameters vary depending on the linear function and very closely on the exponential function.

In table 2 we present the values of the micro-hardness of the bearing race for the internal ring 6210-20, as well as the empirical relations of the functions.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

To exemplify we present the diagram of empirical models, tables with estimated parameters and the relations of the functions which describe best the variation of micro-hardness (values of the relations "bold" in table 1), are presented in figures 5 and6.

One can notice that in the case of internal ring the microhardness of the bearing races for all the working parameters vary depending on the inverted function.

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

4. CONCLUSIONS

When processing through cold plastic deformation through rolling of the bearing rings they get superficially hardened.

The experimental research regarding the variation of microhardness with the depth of the hardened layer when modifying the values of the work parameters show that:

--in the case of the external ring the micro-hardness vary depending on a linear function, very closely being the exponential one.

--in the case of the internal ring the micro-hardness varies depending on the inverted function.

5. REFERENCES

Pruteanu ,O.V., Carausu, C. Paraschiv, Sarbu, I., (2006). The influence of the working parameters on the parameters of the superficial layer when procesing the steels through grinding in the rolling's technology. [TEXT NOT REPRODUCIBLE IN ASCII], Minsk, Belarus, may, 186-197.

Pruteanu, O.V., Paraschiv, Carausu, C., Sarbu, I., Bunea, M., Bardac, D. (2007). Processing through plastic deformation of the bearing rings. MicroCAD 2007, International Scientific Conference, Miskolc, 143-148.

Pruteanu, O.V., Paraschiv, Pricope, Bunea, C.M., Sarbu, I., Carausu, C. (2007). Considerations Regarding the 100Cr6 Material's Conduct through the cold Rolling of the Bearing Rings, International Journal for Manufacturing Science & Technology, U.S. Library of Congress, vol. 9, no.1, p.51-57, ISSN 1524-1548.

Pruteanu, O.V., Paraschiv, Carausu, C., Sarbu, I., Bunea, M., Bardac, D. (2007). Processing through plastic deformation of the bearing rings. MicroCAD 2007, International Scientific Conference, Miskolc, 143-148.

Wagoner, R.H., Chenot, J.L. (2001). Metal forming analysis. Cambridge University Press. New York.

Tab. 1. Micro-hardness of the 6210-10 external ring's bearing races

 Micro hardness [HV.sub.05]

 Parameters [h.sub.1] [h.sub.2] [h.sub.3]

 P = 8,0 MPa A = 34mm/min 302 309 297
 P = 7,0 MPa V = 68 rpm 302 306 302
 P = 6,0 MPa 298 303 295
 P = 5,5 MPa 309 303 295

A=34,0 mm/min P = 5,5 Mpa 315 309 309
A=30,0 mm/min V = 68 rpm 302 301 302
A=27,5 mm/min 302 309 303
A=25,0 mm/min 312 309 295

V = 82,0 rpm P = 5,5 Mpa 297 299 287
 V = 76 rpm A = 34mm/min 301 309 303
 V = 68 rpm 311 303 308

 Micro hardness [HV.sub.05]

 Parameters [h.sub.4] [h.sub.5]

 P = 8,0 MPa A = 34mm/min 283 281
 P = 7,0 MPa V = 68 rpm 295 289
 P = 6,0 MPa 378 246
 P = 5,5 MPa 250 207

A=34,0 mm/min P = 5,5 Mpa 266 269
A=30,0 mm/min V = 68 rpm 301 286
A=27,5 mm/min 295 287
A=25,0 mm/min 287 265

V = 82,0 rpm P = 5,5 Mpa 280 260
 V = 76 rpm A = 34mm/min 282 287
 V = 68 rpm 289 265

 Parameters Dependency relation

 P = 8,0 MPa A = 34mm/min [HV.sub.0.5] = [315,4.e.sup.-0,046.h]
 P = 7,0 MPa V = 68 rpm [HV.sub.0.5] = [310,1.e.sup.-0,025.h]
 P = 6,0 MPa [HV.sub.0.5] = [281+45,4.h-23,7.h.sup.2]
 P = 5,5 MPa [HV.sub.0.5] = 350 - 51,4.h

A=34,0 mm/min P = 5,5 Mpa [HV.sub.0.5] = 334,1 - 27.h
A=30,0 mm/min V = 68 rpm [HV.sub.0.5] = 308 - 6,4.hy
A=27,5 mm/min [HV.sub.0.5] = [312,7.e.sup.-0,03.h]
A=25,0 mm/min [HV.sub.0.5] = 328,4 - 23,2.h

 V=82,0 rpm P = 5,5 Mpa [HV.sub.0.5] = 312,5 - 18,6.h
 V =76 rpm A = 34mm/min [HV.sub.0.5] = 312,9 - 11.h
 V=68 rpm [HV.sub.0.5] = 327 - 21,2.h

Tab. 2. Micro-hardness of the 6210-20 internal ring's bearing
races

 Micro hardness [HV.sub.0.5]

 Parameters [h.sub.1] [h.sub.2] [h.sub.3]

P = 4,5 MPa A=25mm/min 270 280 289
P = 4,0 MPa V=118 rpm 283 295 301
P = 3,5 MPa 274 289 289
P = 3,0 MPa 272 286 291

A=27,5 mm/min P = 4,0 Mpa 280 283 291
A=25,0 mm/min V = 118 rpm 271 281 287
A=22,5 mm/min 270 280 290

V=118 rpm P = 4,0 Mpa 272 298 302
V=98 rpm A = 25mm/min 285 306 294
V=84 rpm 285 291 290

 Micro hardness
 [HV.sub.0.5]

 Parameters [h.sub.4] [h.sub.5]

P = 4,5 MPa A=25mm/min 291 281
P = 4,0 MPa V=118 rpm 301 294
P = 3,5 MPa 290 292
P = 3,0 MPa 281 263

A=27,5 mm/min P = 4,0 Mpa 289 268
A=25,0 mm/min V = 118 rpm 294 289
A=22,5 mm/min 291 286

V=118 rpm P = 4,0 Mpa 295 290
V=98 rpm A = 25mm/min 298 312
V=84 rpm 306 298

 Parameters Dependency relation

 P = 4,5 MPa A=25mm/min [HV.sub.0.5]=292 - 10,8/h
 P = 4,0 MPa V=118 rpm [HV.sub.0.5]=304,6 - 10,3/h
 P = 3,5 MPa [HV.sub.0.5]=296,7 - 10,8/h
 P = 3,0 MPa [HV.sub.0.5]=246+63.h-[22,6.h.sup.2]

A=27,5 mm/min P = 4,0 Mpa [HV.sub.0.5]=258,6+46.h-16,[6.h.sup.2]
A=25,0 mm/min V=118 rpm [HV.sub.0.5]=296,2 - 12,9/h
A=22,5 mm/min [HV.sub.0.5]=294,7 - 12,45/h

 V=118 rpm P = 4,0 Mpa [HV.sub.0.5]=304 - 14,2/h
 V=98 rpm A=25mm/min [HV.sub.0.5]=309,65 - 11,7/h
 V=84 rpm [HV.sub.0.5]=291,3 + 10,3ln(h)