Rolled Round Research Articles

Theoretical study of the process of balls rolling with a diameter of 40 mm on a ball rolling mill

The following calibration scheme for rolling round steel is used for producing thermally hardened grinding balls with a diameter of 40 mm at JSC SSGPO for 320 variety rolling mill: a round billet with a diameter of 40 mm is produced from the initial billet of 120 × 120 mm. In the last developed scheme the square billet 150x150 mm is used as an initial billet for whole mill where the round steel with diameter of 40 mm is obtained from the above mentioned billet and then this round steel is used for production of balls with a diameter of 40 mm. Computer simulation of the ball rolling process in the Simufact Forming program was performed. The results of strain state distribution showed that the maximum processing level in the surface layers of balls is observed, while the stress state distribution showed that in the surface layers prevail high compressive stresses up to −400 MPa. Such stress-strain state leads to formation of gradient structure in the ball cross-section, where the surface layers will have more high mechanical properties. That is the most optimal result for details worked in condition of high values of friction.

INFLUENCE FRONT TENSION ON DEFORMED STATE DURING ROLLING ROUND BARS IN OVAL CALIBER

The purpose of this work is to study the effect of forward tension on the deformed state when rolling round bars in an oval caliber. The work includes experimental and theoretical parts. The experimental part of the work was done in the laboratory. Theoretical part is divided into two other parts - computer modeling and calculations using empirical formulas. The mathematical model was developed in the software package QForm 2D / 3D wich using for modeling and optimization of metal forming processes. Modeling was made for a quarter of the sample, which allowed reducing the time of task solution. Based on previous studies for the conditions of the real experiment on the contact of the sample with the rolls chose the law of friction Coulomb’s with a coefficient of friction of 0.45, most accurately corresponds to the conditions of the experiment. Other boundary conditions are selected from the standard libraries of the QForm software system according to the conditions of the real experiment. Comparison of the calculation results with the experimental data shows that the error does not exceed the engineering accuracy, that is, the process of rolling round samples in an oval caliber with a tension can be studied, based on the results of simulation in QForm. Comparison of the calculation results by the proposed formula and as a result of mathematical modeling showed that the error of determining the profile width by the empirical formula and when modeling in the software package QForm 2D / 3D are close to each other. In other words, both formula and model can be used in engineering calculations anyway. The results of theoretical and experimental studies show that under the influence of front tension reduces the value of widening when rolling round samples in oval calibers. This influence must be taken into account when calculating the deformation mode in finishing wire blocks. The results of work can be used in automated systems of modern rolling mills, which will allow to develop innovative resource-saving technologies of wire rod production on the existing equipment with lower consumption factor as compared to the existing equipment.

Dynamic Measurement for the Diameter of A Train Wheel Based on Structured-Light Vision.

Wheels are very important for the safety of a train. The diameter of the wheel is a significant parameter that needs regular inspection. Traditional methods only use the contact points of the wheel tread to fit the rolling round. However, the wheel tread is easily influenced by peeling or scraping. Meanwhile, the circle fitting algorithm is sensitive to noise when only three points are used. This paper proposes a dynamic measurement method based on structured-light vision. The axle of the wheelset and the tread are both employed. The center of the rolling round is determined by the axle rather than the tread only. Then, the diameter is calculated using the center and the contact points together. Simulations are performed to help design the layout of the sensors, and the influences of different noise sources are also analyzed. Static and field experiments are both performed, and the results show it to be quite stable and accurate.

Fe-Simulation of Hot Continuous Rolling of 40Cr Alloy Steel Round Bar and Roll Pass Design

40Cr alloy steel is widely used in the mechanical manufacturing industry and the quality of its rolled round bar has a great consequence on the quality and useful time of the final mechanical parts. By analyzing the characteristics of thermal plasticity of 40Cr steel, the Hensel-Spittel flow stress model of 40Cr steel was established in this study. For the possible continuous rolling schedule of Φ80mm 40Cr steel from 200mm×200mm billet, the advanced technology of viscoplastic FEM by LARSTRAN/SHAPE was used to create 3-D thermo-mechanical coupled simulation models for 8-pass hot continuous rolling processes. From the rolling process simulation the stress, strain, temperature distribution and rolling force variation were obtained. The simulation results included the comparison of plastic deformation of round pass with curved side wall and round pass with straight-side wall as well as the cause of rolling defect (e.g. crack). Based on the numerical analysis the reliable roll pass sequence wa constructed, which was verified by actual tests.

Effect of Hay Feeding Methods on Cow Performance, Hay Waste, and Wintering Cost

<h2>ABSTRACT</h2> A 3-yr investigation was conducted to determine the effect of hay feeding methods on cow wintering cost. A conventional method of rolling round bales out on the ground was compared with shredding round hay bales on the ground with a bale processor and with feeding hay in a tapered-cone round bale feeder. The cows used in the study were in the third trimester of pregnancy and were fed for an average of 59 d during the test period. Data recorded from the multipleyear study was then used to prepare an economic analysis model with operating budgets for 100- and 300-head reference herds. Feeding bales in a tapered-cone round bale feeder increased cow weight gain (P < 0.01), tended to increase rib fat depth (P = 0.06), reduced estimated hay consumption by an average of 10.2% compared with rolling bales out on the ground or using a bale processor to shred hay on the ground (P < 0.01), and reduced hay waste in the first 2yr of the study when alfalfa-grass hay was fed, but not in the last year when oat hay was fed. The tapered-cone round bale feeder reduced waste, decreased the amount of hay required per cow, and decreased wintering cost per cow while maintaining body condition. Overall, for the 3yr evaluation period, using the tapered-cone round bale feeder reduced wintering cost by 21.0% for a 100-cow reference herd and 17.6% for a 300-cow reference herd compared with feeding with a bale processor.

3D FEM modelling and its experimental verification of the rolling of reinforcement rod

In this paper the computer simulation of the rolling round reinforcement rod is presented. It has been performed in order to define the specific features of the mode of metal flow in the roll gap and to determine the effect of the shape and dimensions of the stock oval on the filling of the elements of the finished rod. The simulations of the rolling round reinforcement rods were carried out using the Forge3 commercial program. To compare the simulations and the real rolling process, trial rolling of reinforcement rod was carried out. The stock material was a steel rod of an oval cross-section. The results of computer studies and real tests show a good compatible of the shape and dimensions of finished rod.

Fatigue life prediction techniques for notch geometries in titanium alloys

This paper focuses on the α+β titanium alloy, Ti–6Al–4V, in a range of microstructural conditions from fine grained alpha and retained beta (annealed) through bimodal morphologies consisting of primary alpha and transformed beta to coarse fully transformed structures produced by heat treatment above the beta transus. Material was taken from several processing routes including cross rolled plate, hot rolled round bar stock and small disc forgings. The strain control LCF response measured from plain testpieces is related to data obtained on a variety of notch geometries with K t factors in the range 1.4 to 4.7. A correlation technique based on the parameter K tΔ σ for notches and Δ σ for plain specimens with Δ σ the stress range defined at the ‘stabilised’ or ‘saturated’ condition is used to relate the data sets. Notch behaviour that is not consistent with this correlation is related to the microstructural condition, the cyclic stress–strain behaviour of that condition and the presence of `fatigue sensitive' features.

Magnetic fields in the spiral arms of galaxies

Ordered magnetic fields observed in the Galaxy are approximately aligned along the axis of the spiral arms. The magnetic field strength is ∼3 microgauss but the total energy of the galactic magnetic field is as high as ∼1055ergs. The magnetic field direction is observed to reverse between adjacent spiral arms and this configuration requires an electric current sheet to loop each arm. Mechanisms for creating an electric current are discussed and attention is focused on the possibility of a net proton current. This requirement may be compatible with the indications that partially ionized gas is ‘rolling round’ the spiral arms as they orbit the Galaxy. There is evidence which suggests that the ‘direction of roll’ of the gas also reverses between adjacent spiral arms. There is a well known coincidence between the energy density of the galactic magnetic field and the energy density of turbulent gas motions, both are close to 1eVcm−3. Possible origins for these energies and the implications of this coincidence are discussed.

Relation between Local Strain and Macroscopic Strain in Static Deformation of Plain Specimens of Isotropic Carbon Steel.

Tensile and torsional tests were carried out on the plain specimens of isotropic carbon steels. One of the materials is an annealed cast carbon steel and the other is a rolled round carbon steel bar (S45C) which was diffusion-annealed. Fine grid lines were drawn on the surface of specimens with a diamond-point needle. The lines were fine enough not to influence the structure of the slip bands. The local strains were measured from the elongated or distorted grids. The local deformations were not uniform in either tension or torsion, and most of the local strains were not the same as the given macroscopic strain. That is, there existed various local strains which were from near zero to two or three times the given macroscopic strain. It showed the minor differences of the variation of local strains between tensile test and torsional test.

Nonuniformity of Local Strain and Strain Concentration in Static Deformation of Plain Specimens of Rolled Round Carbon Steel Bars.

Tensile and torsional tests were carried out on the plain specimens of rolled round carbon steel bars (S15C, S35C, S45C). Each specimen is regarded as an anisotropic material because it has a banded structure of ferrites and pearlites which were produced by rolling. Fine grid lines were drawn on the surface of specimen with a diamond-point needle. The lines were fine enough not to influence the structure of the slip bands. The local strains were measured from the elongated or distorted grids. The local deformations were not uniform in both tension and torsion, and most of the local strains were not the same as the given macroscopic strain. That is, there existed various local strains which were from near zero to several times the given macroscopic strain. The variety of local strains in torsion was greater than that in tension. The banded structure affected the local strain greatly in torsion, but hardly affected that in tension. Strain concentration in tension was small ; however, in torsion, this was large within the ferrite sandwiched between pearlite bands. When the materials had a clear banded structure and large binding force due to pearlites, the banded structure greatly influenced the local strain in torsion. The result of this study is important to the understanding of the fatigue of plain specimens of rolled round carbon steel bars.

Fatigue Limit and Small-Crack Growth Law in Rotating Bending and Torsional Fatigue of Rolled Round Carbon Steel Bars which are Quenched and Tempered.

Rotating bending and torsional fatigue tests were carried out on plain specimens and small-hole specimens of rolled round carbon steel bars which were quenched and tempered. The present specimens are regarded as isotropic materials although the original materials have a banded structure. The fatigue limit ratio between rotating bending and torsional fatigue (τw/σw) in the specimens is different from that in an annealed rolled round carbon steel bar, and is approximately the same as that in isotropic cast carbon steel. We should use isotropic materials in discussing effects of combined stresses on fatigue. In the torsional fatigue tests, crack propagation on plain specimens was of the shear type in the initial stage and of the tension type in the later stage. Cracks of the shear type were generated in both the circumferential and axial directions. The crack growth laws in bending and torsion are expressed by dl/dN∝ σ anl or dl/dN∝τanl. The dependency of 1/Nf on the stress amplitude σa and τa in bending and torsional fatigue is approximately the same as the dependency of the crack growth rate on σa or τa, respectively.

Fatigue Limit and Small-Crack Growth Law in Rotating Bending and Torsional Fatigue of Isotropic Carbon Steel Plain Specimens.

Rotating bending and torsional fatigue tests were carried out on plain specimens and small-hole specimens of annealed cast carbon steel. The specimens are regarded as isotropic. The fatigue limit ratio between rotating bending and torsional fatigue (τw/σw) in the isotropic carbon steel is different from that in a rolled round bar of carbon steel. We should use isotropic materials in fatigue tests under combined stresses. In torsional fatigue, crack propagation on plain specimens is of the shear type in the initial stage and tension type in the latter stage. Cracks of the shear type were generated in both the circumferential and the axial directions. The crack growth laws in bending and torsion are expressed by dl/dN= C1τnal. The dependency of 1/Nf on the stress amplitude τa in the torsional fatigue is nearly the same as the dependency of the crack growth rate on τa.

The Operation of Automatic Ultrasonic Inspection System of Immersion Method

The ultrasonic testing is usually used for inspection of internal defects of steel billets and bars. The former has advantage of reduction of materials for inspection, and disadvantage of difficulties of inspection for bend, twist, bur and hair crack of material. In the latter case it is inverse, so we inspect billets for detection of serious defects (ex. primary pipe) and bars for detection of minute defects (ex. secondary pipe, nonmetallic inclusion, hair crack). This is the reason why we need the automatic ultrasonic inspection system of immersion method. The system is composed of two lines and dual-scanning for one line.The inspection rate is 480 pieces/hour at the scanning speed of 30m/min for hot rolled round bars of 34∼75mm diameter. In practical operation, the defect over F 30% at the gain of STB V15-1.4F 80% and over 8mm to 50mm in length can be detected at the reliability of over 90% and error marking for noise is less than 2% without descaling.Now, with double inspecting methed for billets and bars our products are guaranteed to over 99.99% for harmful internal defects.

Increasing efficiency

When Rolls Royce (1971) Ltd designed their East Kilbride Warehouse for their aero engine spares, they required a conveyor system. This had to carry boxes either 2 or 31/2 ft sq and weighing up to 160lb. On the ground floor, the system had to convey the boxes up to any of 24 inspection tables and then on to any of 36 packing stations. Between there had to be facilities for holding stock should the output of the packaging section be slower than the inspection. This was stipulated as being more important than the actual carrying capacity of the system. Finally, process is reversed, the slats progressing the boxes forward and rolling downwards just ahead of the start of the next conventional conveyor. Space is saved because the slats descend in the vertical before rolling round to receive the next box.

Finishing-stand roll design of a light-section mill for rolling round and other common shapes

Finishing-stand roll design of a light-section mill for rolling round and other common shapes

Technology and mills for rolling round periodic sections

Technology and mills for rolling round periodic sections