RESEARCHING ABOUT THE BEARING OF THE TUBULAR WIRES AND BI-METAL COMPONENTS FOR HARDENING THE SHARES OF THE PLOUGH BODY

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1 RESEARCHING ABOUT THE BEARING OF THE TUBULAR WIRES AND BI-METAL COMPONENTS FOR HARDENING THE SHARES OF THE PLOUGH BODY CERCETĂRI PRIVIND COMPORTAREA SÂRMELOR TUBULARE SI A COMPONENTELOR BI-METAL UTILIZATE PENTRU DURIFICAREA BRĂZDARELOR DE LA TRUPIŢĂ Abstract. The paper presents the comportment of some samples taken from the shares of the plough body after it was hardened before by depositing in alveolus using tubular wires with composite core. This comportment is showed by laboratory testing, on a specialized stand, realized so as it can distinguish the wear for different samples taken from plough body (hardened or unhardened) at intensive wear. Delia BRAHARU, Valentin VLĂDUŢ, Silviu BĂJENARU, Mihai MATACHE, Elena POSTENICU *INMA Bucharest Corresponding author: Delia Braharu, deliabraharu@yahoo.com Key words: share, wear, welding, sample, friction, reliability Cuvinte cheie: brăzdar, uzură, sudură, epruvetă, frecare, fiabilitate 67 Rezumat. Lucrarea urmăreşte comportamentul unor probe prelevate din brăzdarul unei trupiţe după ce acesta a fost durificat în prealabil prin depuneri în alveole cu sârma tubulară cu miez compozit. Acest comportament este exemplificat prin testări în laborator, pe un stand specializat, realizat astfel încât să se poate scoate în evidenţă uzura diferitelor probe prelevate din trupiţă (durificate şi nedurificate) la uzură intensivă. INTRODUCTION In the actual conditions of development of the national economy agriculture can not be conceived without a height grade of mechanization. Is known the facts that, in the car parts market prices, 7 8% are charges for the used materials. These materials, when worn parts are reconditioned, can be used repeatedly. In the last years in Romania, are used more and more new techniques and new marks, made abroad. To obtain spare parts for agricultural machinery is very expensive. So it is necessary to find new methods for reconditioning agricultural machinery parts, able to increase the reliability of agricultural techniques and manufacturing industry. Share wearing intensity depends not only of soil condition, but also of its homogeneity grade with depth properties. If in - years, the tilt is not changed, share wears on the bottom of the furrow increases, cutting side would be in this case collateral with the bottom of the furrow. Efficiency of using welding deposits for active operating parts hardening and reconditioning of the spare parts has been demonstrated by many researchers from our country and abroad, but actual recommendations refers mostly to certain parts, used in certain exploitation conditions. Considering all these, in this study has been realized researches about physicomechanical and wearing characteristics of the materials taken from a share with welding deposits, in alveolus, the new type of additional material (figure ) - tubular wires with composite core, being realized by our partners Tehnomag and Sudotim.

2 The samples have been analyzed in our laboratories as follows. THE ANALYSE OF THE PHYSICO-MECHANICAL CHARACTERISTICS. THE ANALYSE OF THE WEARING CHARACTERISTICS. Analyze description In this stage have been effectuated analyses for samples taken from the areas presented in the next image, steel without any hardening, respectively from bead area. 4 Fig. Assay areas of the samples,4 not hardened steel samples,, bead area samples It has been studied from physico-mechanical and wearing characteristics of the materials tested to friction, the following samples, in shape of pastilles, with parallelepiped geometry, with square base, 6 mm a side and variable height. H L Fig. Sample geometry (L=6 mm, H as in measurement file) L Samples has been cut with a cutting machine with pump and cooling tank Mecatome T/, then polished, using a polishing machine MecapolP6. Fig. Cutting a sample from unhardened zone Fig. 4 Polished samples, on the friction side of the share that works into the soil 68

3 Linear initial dimensions of the samples: Table Measured dimensions Sample Sample a Sample Sample 4 Sample L [mm] 6 6,, 6,6 6,6 l [mm],4 4, 4, 4,9,46 h [mm], 4,6,6 4,67 The hardness has been measured with a hardness-testing machine HMV Shimadzu, that can convert Vickers hardness to Rockwell hardness. Table Sample number Sample Sample Sample Sample 4 Sample Vickers hardness HV Rockwell hardness HRC 74 4, 77, 96 9, 4,6 4,6, , 47,,7 Conditions of testing Applied force F= 9,6 N Pressure standing t= 4 sec To determinate specifically friction properties (friction coefficient, wear intensity, friction coefficient stability), it has been used a special stand fig.-7, with the possibility to measure necessary factors to determinate by calculating these measurements values. Fig. - Stand for testing samples to friction. Assembly view. cast-iron friction disc;.engine- disc gear;. weights set to realize the pressure 4 Fig. 6 Testing stand. Detail with the measurement and control apparatus. tensometer amplifier;. electronic tachometer with digital display;. laptop with acquisition board to measure friction force; 4. digital thermometer;. digital calliper rule 69

4 Through the transmission from engine, friction cast-iron disc gets a rotating motion with constant speed. The sample is fixed in the chuck (fig. 8) then is put in contact with castiron disc, being controlled normal pressure on the disc with a calibrated weights set. The contact surface of the sample with the disc is calculated in table, and is represented by the square side of the sample. With the charging cell it is measured friction force that appears at the contact of the sample with the cast-iron disc, and that opposes the motion. Also it is known disc diameter and friction time is being registered, so that we can calculate road length and peripheral speed. At the beginning and at the end of each test, each sample was weighted. Fig. 7 Catching the sample in the chuck, detail Testing stand represents a technical accomplishment witch can realize friction materials testing in dynamic regime, in initial conditions of temperature, sliding speed and preset pressing charge, starting with usual values to maximum admitted limits of the tested material. Friction characteristics tests results Determination of the friction coefficient (µ) Friction coefficient has been calculated: F, N when: F = measured friction force, in dan; N = normal pressing force (dan); Average values calculated can be seen in tables -7. The results of the tests are: Determination of friction coefficient µ sample No. Sample - N= 8, dan Sample - N=,46 Kg crt. Ff [N] µ µ med Ff [N] µ µ med 8, 9,8,9 8,,,,9,4 4,,74 4 9,8, 7,,98 9,,,8,8 6 8,4,6 7,,99 7 8,, 6,6,94 8 9,9, 6,,9 9 9,, 6,89 8,8, 7 8,8, Table µ sample,88,8

5 Friction Forta force de fracare [N] [N] 4 Sample Epruveta Sarcina Normal normala force N= N=8Kg 8 Kg Time Timpul [s] [min] Sarcina Normal normala force N= N= Kg Kg Friction Forta de force fracare [N] [N] Sample Epruveta 4 Sarcina Normal normala force N= N=8Kg 8 Timpul Time [min] [s] Sarcina Normal normala force N= N= Kg Kg Table no. 4 No. Sample - N= 8, Kg Sample - N=,46 Kg crt. Ff [N] µ µ med Ff [N] µ µ med µ sample,6, 9,,8,44 8,7, 7,7,7 8,9, 4 7,99 8,8, 7,8,9,6,9 6 7,4,4,69,6,8 7 7,7,7,4,7 8 6,8,97,7,66 9 6,87,69,6,8,,7 Sample Epruveta Sample Epruveta Friction Forta frecare force [N] Sarcina Normal normala force N=8 8 Kg Timpul [min] Sarcina Normal normala force N= N= Kg Time [s] Friction Forta force frecare [N] Sarcina Normal normala force N=8 Kg 8 Kg Timpul [min] Sarcina Normal normala force N= Kg Kg Time [s] Table No. Sample - N= 8, Kg Sample - N=,46 Kg crt. Ff [N] µ µ med Ff [N] µ µ med µ sample,7 6,9,, 7,,9,4,4 8,7, 4,8,8,9,48,8,,9,6,477 6,,7,469,97 7,9,6, ,,6,,69 9 4,,66,,9 4,4,69,6,6 7

6 Sample Epruveta Sample Epruveta Friction Forta de force frecare [N] [N] Sarcina Normal normala force N= 8 Kg Kg Time Timpul [min] Sarcina Normal normala force N= Kg Friction Forta de force frecare [N] Sarcina Normal normala force N= 8 Kg Timpul [min] Sarcina Normal normala force N= Kg Time [min] Table 6 No Sample 4 n= rpm Sample 4 n= rpm Sample 4 n= rpm crt Ff [N] µ µ med Ff [N] µ µ med Ff [N] µ µ med 9,7,48 4,,7 8,4, 6,,48 4,,7 8,, 6,,49 4,6,7 8,8, 4 6,6,49 44,,7 9,, 6,, 4,4,6 8,7,,49,68 6 6,,48 4,6,6 9,,, 7 6,8,,6,7 9, 8 6,6, 4,,7 8,, 9 6,9, 46,8,7 9,, 6,7, 4,,7 8,7, 7 Turatie rpm Turatie rpm Turatie rpm Turatie rpm Epruveta 4 Sample 4 Epruveta 4 Turatie rpm Sample 4 Turatie rpm Friction Forta frecare force [N] [N] Friction force [N] Forta frecare [N] Time timpul [min] timpul Time [min] Table 7 No crt Sample n= rpm Sample n= rpm Sample n = rpm Ff [N] µ µ med Ff [N] µ µ med Ff [N] µ µ med,4,4 4,,4,4, 7,,46 4,,,7,6 6,6,49 4,6, 4,,7 4 6,7,49 44,,6,,7 6,,49 4,4,,9,6,484, 6 6,9,49 4,6,,7,7,7 7 6,4,49,6,,,8 8 6,49 4,,6 4,7,8 9 6,, 46,8,8,,8 6,4, 4,,6,8 7

7 7 6 Turatie rpm Turatie rpm Turatie rpm Epruveta Sample Turatie rpm Turatie rpm Epruveta Sample Turatie rpm 7 6 Friction Forta frecare force [N] [N] Friction Forta frecare force [N] [N] timpul [m Time [min] timpul Time [min] The results of wearing tests determinations Wear intensity determination (I UZ ) Wear intensity is the ratio between material wear mass express and consumed testing energy for the sample to run a given road. U ZM I UZ (g/dan*m) F f * L when: U ZM = material wear determined gravimetric, in gram; F f = friction force as the effect of pressing charge N, in dan; L = road length run by he sample on the surface of the disc in a given time, in m. Average values calculated can be found in tables 8. a) Sample Table 8 Sliping speed [m/s] Normal force [dan] Friction time [min] Medium friction force [N] Friction Coef. µ Contact Weight [g] surface [cm ] before after Mass wear [g] Wearing intensity [g/n*m] Sample, 8, 69 8,9,8,46,4,78.6,47* -7,,46 69,6,88,46,78 4, ,867* -7 b) Sample Table 9 Sliping speed [m/s] Normal force [dan] Friction time [min] Medium friction force [N] Friction Coef. µ Contact Weight [g] surface [cm ] before after Mass wear [g] Wearing intensity [g/n*m] Sample, 8, 69 7,84,9,4 9,849 9,96. 6,8* -7,,46 69,8,6,4 9,96 8,7.9,7* -7 c) Sample Table Slipping speed [m/s] Normal force [dan] Friction time [min] Medium friction force [N] Friction Coef. µ Contact Weight [g] surface [cm ] before after Mass wear [g] Wearing intensity [g/n*m] Sample, 8, 69,6,477,4,4647,49.,7* -7,,46 69,76,469,4,49,7.77 8,4* -7 7

8 Sample 4 d) Sample 4 Table Rotation Sliping Normal Frictio Medium Friction Contact Weight [g] Mass Wearing speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm ] before after [g] [g/n*m],94,46 6,4 6,4,494,8 4,948 4,78,68,86* -7 4,88,46,8 4,8,676,8 4,78 4,77,9,78* -7 6,8,46 769,8 8,86,8,8 4,77 4,7,6,474 * -7 Sample e) Sample Table Rotation Sliping Normal Frictio Medium Friction Contact Weight [g] Mass Wearing speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm ] before after [g] [g/n*m],94,46 6,4 6,4,486,498 6,498 6,486,74,8* -7 4,88,46,8 4,6,,498 6,486 6,4498,8,887* -7 6,8,46 769,8,7,7,498 6,4498 6,496,.764 * -7 Observations: It can be observed, in the firs case of samples, the fact that once we increased normal pressing charge from N= 8, Kg, to N=,46 Kg friction coefficient increased too, as a result of the friction between the disc and the sample, contact surface between these too increases too. In the second case, samples 4 and, that has been tested in different regimes of rotation speed, respectively, and rot/min, it can be noticed obviously the tendency of decreasing of the friction coefficient once the speed increasing. As it can be seen in figure 4 cutted samples although polished, they couldn t get the same friction surface, because the welding belt has an inferior thickness to the dimension needed to catch it on our testing stand, respectively 6x 6 mm. So, those three hardened samples, has been tested, in fact, to a higher pressing force, having the surface inferior to those unhardened, this has negatively influenced the interpretation of wear intensity (tab.8-). So it s been decided to effectuate a new series of tests with other four samples, cutted: two from hardened zone (samples 6 and 8) and other two unhardened (samples 7 and 9), adapted to a good catch in our tasting stand, but worked on a lathe to a diameter of 8 mm, so the friction surface to be the same for all 4 and to contain in the whole the welding belt of adding material, as can be seen in following pictures (figure 9). Figure 9 Samples has been polished, then was determined their hardness with a microhardness-testing machine HMV Shimadzu (tab. ). 74

9 Sample number Vickers hardness HV Rockwell hardness HRC Conditions of testing Sample 6 Sample 7 Sample 8 Sample 9 6,,,6 8 6,4 9 7,7 8, 6 6,4 68 9, Applied force F= 9,6 N Standing pressing t= 4 sec Table Determination of the friction medium coefficient µ med, has been made by measuring friction force every minute, for ten minutes. Table 4 Crt Sample 6 (n= rpm) Sample 6 (n= rpm) No. Ff [N] µ µ med Ff [N] µ µ med,667,,489,6,89,,,8,6,4, 4,8,6,4,44,9,644,4,44,689 6,9,644,6,69,46 7,667,,6 8,8,6,,6 9,9,644,8,7,9,66,,6 turatie = rpm turatie = rpm Sample 6 Epruveta 6 turatie = rpm turatie = rpm Epruveta 6 Sample 6,, Friction Forta frecare force [N] [N],,, Friction Forta force frecare [N],,, Time Timp [min] Time Timp [min] Table Crt Sample 7 (n= rpm) Sample 7 (n= rpm) No. Ff [N] µ µ med Ff [N] µ µ med,667,4,,9,644,,6,98,66,8,7 4,94,6,6,78,667,6,89,66 6,,678,6,78,844 7,97,66,7,6 8,9,66,7,64 9,667,8,6,96,68,7,6 7

10 , turatie = rpm turatie = rpm Epruveta turatie = rpm Sample 7 Epruveta Sample 7 7 turatie = rpm, Friction Forta frecare force [N],,, Friction Forta frecare force [N] [N],,, Time Timp [min] Time Timp [min] Table 6 Crt Sample 8 (n= rpm) Sample 8 (n= rpm) No. Ff [N] µ µ med Ff [N] µ µ med,9,644,4,44,9,649,4,,667,8,9 4,,689,4,,9,644,4,,69 6,667,4,44,96 7,,678,,6 8,667,4, 9,8,6,4,8,667,4,44 turatie = rpm turatie = rpm Sample 8 Epruveta 8 turatie = rpm turatie = rpm Sample 8 Epruveta 8,, Friction Forta frecare force [N],,, Friction Forta frecare force [N],,, Time Timp [min] Time Timp [min] Table 7 Crt Sample 9 (n= rpm) Sample 9 (n= rpm) No. Ff [N] µ µ med Ff [N] µ µ med,9,644,,,9,66,8,9,98,66,4, 4,9,644,,6,667,6,78,666 6,,7,8,7,47 7,667,6,78 8,9,66,,6 9,,689,6,78,667,,6 76

11 Friction Forta force frecare [N],,,, turatie = rpm turatie = rpm Sample Epruveta 99 Friction Forta frecare force [N],,,, turatie = rpm turatie = rpm Sample 9 Epruveta Timp Time [min] [min] Timp Time [min] a) Sample 6 Table 8 Rotation Sliding Normal Frictio Medium Friction Contact Mass Wearing Weight [g] speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm ] [g] [g/n*m] before after Sample,94 4, 6,4,87,68, 9,849 9,8,4 9,7* ,88 4,,8,446,4, 9,8 9,8,8 4,99* -7 b) Sample 7 Table 9 Rotation Sliding Normal Frictio Medium Friction Contact Mass Wearing Weight [g] speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm] [g] [g/n*m] before after Sample,94 4, 6,4,97,66, 4,4 4,97,87,77* ,88 4,,8,6,84, 4,97 4,6,7 4,99* -7 c) Sample 8 Table Rotation Sliding Normal Frictio Medium Friction Contact Mass Wearing Weight [g] speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm] [g] [g/n*m] before after Sample,94 4, 6,4,967,69,,89,87,64 64,7* ,88 4,,8,48,9,,87,888,49,84* -7 d) Sample 9 Table Rotation Sliding Normal Frictio Medium Friction Contact Mass Wearing Weight [g] speed speed force n time friction Coef. surface wear intensity [rpm] [m/s] [dan] [min] force [N] µ [cm ] [g] [g/n*m] before after Sample,94 4, 6,4,998,666,,4,4,4,694* ,88 4,,8,496,4,,4,6,49 9,7* -7 CONCLUSIONS As samples 4 and, that has been tested in different speed regimes, we ve effectuated tests also for this last series at rotation speed respectively rot/ min, using a normal pressing charge of 4, Kg. This time can been observed a decreasing of the friction coefficient once the rotation speed increases, too. 77

12 Also, for each testing set, samples has been weighted before and after, so it can be calculated mass wear after every ten minutes. For unhardened samples 6 and 8 this is even greater. We ve considered concluding this last testing series because we ve did it in the same initial conditions for all four samples. So, with 7 and 9 samples, hardened with the new type of tubular wire with composite core, for which wearing intensity is obviously lower, relieves that they have a higher hardness and wear resistance, in laboratory conditions. BIBLIOGRAFY. BRAHARU D, GÂNGU V, ş.a. Fundamental research regarding the methods of anti-wear deposit, adaptable to components for agricultural equipments, Bucharest, 7. DUMITRU TOMESCU, GHE. MANCIU, VALENTIN S. Agricultural machinery reliability, Bucharest, 98;. RADU IOVĂNAŞ, DANIELA M. IOVANAŞ Reconditioning and the recovery of the welded parts, Editor UTB, 6 78