Residual tensions in cold plastic deformed surfaces.

Carausu, Constantin ; Sarbu, Ionel ; Pruteanu, Octavian 等

1. WORK CONDITIONS

1.1. Equipments and work conditions

For the rolling tracks' plastic deformation of the bearing's exterior ring type 6210, the Japanese machine, type CRF-120 OR was used, fig. 1, and for measuring the residual tensions, the Measurement System MTS 3000 produced by Hottinger Baldwin Messtechnik was used, fig. 2.

The residual tensions measurement was done by the method of piercing (Johnson et al., 1982), (Wagoner & Chenot, 2001).

The residual tensions' values determination was done by measuring the deformations according to three directions noted a, b and c on the gauge strain (1). The hole was produced with the help of a frontal milling machine set in the piercing device (2) which receives the main movement of splintering through a pneumatic turbine connected to the compressor (6) through a pressure regulator and a distributor (4).

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

The work progress is ensured by the programme installed on the computer (5) which, through the date acquisition board PC-LPM-16, commends step by step the engine situated on the device (2). The deformations measured by the gauge strain were transmitted to the tensometric bridge (3) type Spinder 8, which, being amplified, were transmitted to the computer where, with the help of the programme installed, were transformed in residual tensions (Pruteanu et al., 2006), (Pruteanu et al., 2007).

The processing was done in the following conditions:

--Material: 100Cr6--specific to the bearing rings,

--Diamond milling machine with diameter d=1.7 mm for the plastic deformed ring and 2.0 mm for the semi-finished product,

--Work feed: 0.1 mm/min,

--Work rotation: 300,000 rot/min,

--Maximum hole depth: 2.5 mm.

2. EXPERIMENTAL RESULTS

The residual tensions were measured on two rings; semi-finished ring and cold plastic deformed ring.

In table 1 there are the residual tensions' measurement results for the semi-finished product according to several criteria until the maximum depth of the hall of 1.252 mm, value until which there were noticed differences, and in table 2 the plastic deformed ring's measurement results are shown.

In figure 3, the graphic representations of the residual tensions for the finished (a) and semi finished (b) rings are shown.

3. CONCLUSIONS

From the graphs analysis we can draw the following conclusions:

--at the exterior surface of the semi finished ring, the residual tensions are very high and decrease rapidly with the depth (until 1.5 mm). These are due to the rough turning operation followed by the rectification with insufficient cooling,

--at the exterior surface of the plastically deformed ring at cold, the residual tensions are stretched throughout a much higher depth (0.4 mm) and tend to level out at a value of around 100 N/[mm.sup.2] (Von Mises method).

In future, we will research the difference between the residual tensions in ring processing through grinding (old technology) and in plastic deformed ring.

Likewise, we will compere the durability of the bearing processing through two technology.

[FIGURE 3 OMITTED]

4. REFERENCES

Johnson, W., Sowerby, R., Venter, R.D. (1982). Plain strain slip for metal deformation processes, Pergamon Press.

Pruteanu, O.V., Carausu, C. Paraschiv, Dr., 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, Dr, Pricope, C, 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, Dr., 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.

Table 1. Experimental results--semi-finished product

Depth Smin Smax Von Mises Tresca
[mm] [MPa] [MPa] [MPa] [MPa]

0.013 303.056 821.807 719.831 821.807
0.036 205.853 673.534 597.808 673.534
0.073 113.635 394.428 351.661 394.428
0.121 10.631 236.732 231.6 236.732
0.18 -47.793 189.051 216.933 236.844
0.252 -44.176 175.395 201.154 219.571
0.335 -32.788 161.976 180.616 194.764
0.431 -44.859 141.09 168.071 185.949
0.538 -70.859 119.421 166.567 190.28
0.657 -83.875 107.949 166.56 191.824
0.788 -73.514 106.815 157.054 180.329
0.931 -58.859 105.883 144.595 164.742
1.085 -60.784 89.55 130.985 150.334
1.252 -71.858 73.727 126.084 145.585

Depth Strain (a) Strain (b) Strain (c) Alfa
[mm] [1E [1E [1E Angle
 [10.sub.6]] [10.sub.6]] [10.sub.6]] [[degrees]]

0.013 -12.7 -5.143 -3.587 -16.68
0.036 -27.837 -7.712 -9.087 -24.454
0.073 -36.718 -13.805 -5.948 -13.035
0.121 -39.351 -23.561 4.79 7.942
0.18 -44.288 -35.039 14.836 17.247
0.252 -57.491 -45.492 19.209 17.247
0.335 -74.327 -52.691 22.623 14.486
0.431 -85.676 -57.512 35.102 14.043
0.538 -90.509 -63.052 58.502 16.136
0.657 -99.887 -71.236 81.017 17.171
0.788 -121.037 -78.752 90.668 15.493
0.931 -139.823 -77.847 92.706 12.515
1.085 -135.352 -67.218 104.286 11.667
1.252 -122.135 -66.454 120.013 14.187

Table 2. Experimental results--plastic deformed ring

Depth Smin Smax Von Mises Tresca
[mm] [MPa] [MPa] [MPa] [MPa]

0.013 98.306 471.596 430.936 471.596
0.036 165.178 563.583 501.815 563.583
0.073 256.858 508.149 440.079 508.149
0.121 297.387 491.89 429.084 491.89
0.18 304.651 490.811 429.164 490.811
0.252 282.957 470.211 410.017 470.211
0.335 226.86 397.334 345.255 397.334
0.431 176.783 290.284 253.377 290.284
0.538 124.877 202.381 176.861 202.381
0.657 66.002 174.852 152.934 174.852
0.788 45.578 157.94 140.797 157.94
0.931 53.606 141.786 124.001 141.786
1.085 51.218 125.621 109.407 125.621
1.252 31.854 115.224 111 115.224

Depth Strain (a) Strain (b) Strain (c) Alfa
[mm] [1E [1E [1E Angle
 [10.sub.-6]] [10.sub.-6]] [10.sub.-6]] [[degrees]]

0.013 -5.654 -6.666 -1.726 28.287
0.036 -19.274 -23.199 -8.095 29.785
0.073 -39.52 -37.525 -17.94 19.591
0.121 -66.756 -53.475 -31.879 6.705
0.18 -99.152 -79.776 -49.187 6.325
0.252 -130.22 -114.933 -66.315 13.773
0.335 -148.062 -138.411 -76.618 18.062
0.431 -145.274 -127.25 -76.314 12.756
0.538 -126.111 -81.225 -69.106 -14.945
0.657 -105.503 -32.221 -65.708 -34.779
0.788 -94.185 -14.45 -74.521 -40.997
0.931 -86.788 -26.189 -92.044 -46.19
1.085 -69.333 -30.562 -105.492 -53.821
1.252 -44.203 -10.942 -108.464 -58.084