Showing papers on "Rolling resistance published in 2000"

Rolling contact phenomena

Abstract: In this paper, we treat the rolling contact phenomena of linear elasticity, with special emphasis on the elastic half-space.

Flat Rolling Fundamentals

Abstract: Principle characteristics of steel: structure of metals metallurgical characteristics of steel chemical compositions of steel classification of steel physical properties of steel products metallurgical factors controlling the properties of steels. Deformation of steel: microscopic and macroscopic plasticity analysis of workpiece deformation resistance to deformation in hot rolling roll force and torque in flat rolling friction and lubrication in rolling. Metallurgical aspects of hot rolling process: heat transfer in hot rolling structural changes in steel during hot rolling thermomechanical treatment combined with rolling metallurgical defects in cast slabs and hot rolled products. Rolling mills for flat products: types of rolling mills optimisation and modernisation of hot strip mills. Geometry of flat rolled products: definition of geometrical parameters of rolled products standard dimensional tolerance statistical and analytical dimensional tolerance. Gauge control: principles of measurement of rolling parameters causes of gauge variation gauge control sensors an actuators automatic gauge control systems. Width control: basic principles of width change width change by rolling and pressing optimisation and control of width change process. Profile and flatness control: strip profile and flatness analysis roll thermal expansion and wear backup rolls with specific profiles roll deformation and displacement systems strip profile and flatness control systems.

Road surface friction coefficient estimating apparatus

Abstract: A road surface friction coefficient estimating apparatus is provided for estimating a road surface friction coefficient of a vehicle that is traveling at a steady state The road surface friction coefficient estimating apparatus basically has a driving/braking force controller, a driving force controller, a braking force controller (brake fluid pressure controller), a plurality of wheel velocity sensors, a wheel load sensor and a control unit The driving/braking force controller sets a pre-selected force to be generated and calculates the road surface friction coefficient The driving force controller generates a driving force in accordance with the pre-selected force The braking force controller generates a braking force in accordance with the pre-selected force The wheel velocity sensors produce a wheel velocity signal indicative of a wheel velocity The wheel load detecting sensor produces a wheel load signal indicative of a wheel load The control unit which is part of driving/braking force controller calculates a road surface friction coefficient based on the wheel load, the wheel velocity, and the braking and driving forces The braking force is configured to cancel the driving force

Methods for measuring vertical tire stiffness

Abstract: Vertical stiffness was measured for a 260/80R20 radial ply agricultural drive tire using five methods; load-deflection, non-rolling vertical free vibration, non-rolling equilibrium load-deflection, rolling vertical free vibration, and rolling equilibrium load-deflection. Tests were conducted at three inflation pressures (41, 83, and 124 kPa). Non-rolling free vibration resulted in the highest stiffness for all inflation pressures. Load-deflection and non-rolling equilibrium load-deflection results were similar at all inflation pressures. Rolling vertical free vibration and rolling equilibrium load-deflection results were similar at inflation pressures of 83 and 124 kPa. Non-rolling free vibration is not an adequate method for determining vertical tire stiffness when the tire is represented by a spring and viscous damper in parallel. The discrepancy between load-deflection and free vibration test results was attributed to hysteresis in the tire. Tire properties should be measured at the desired forward velocity when the tire is modeled as a spring and viscous damper in parallel.

Measurement of stress-strain relationship of beech roots and calculation of the reinforcement effect of tree roots in soil-wheel systems

Abstract: Evidence from forestry shows that part of the forest floor bearing capacity is delivered by tree roots. The beneficial effect varies and diminishes with increasing number of vehicle passes. PLAXIS is a commercially available finite element code that can calculate stresses, strains and failure states of soil mechanical problems. It can cope with unsaturated reinforced soil. Tree roots have a stiffness and a failure strength. They show elastic as well as plastic behaviour. They also show fatigue phenomena in repeated loading. Rooting intensity and root patterns of forest trees are complicated, but some information is available. This paper summarizes published data on mechanical properties of tree roots, and presents new measuring results of these properties. The paper further presents results of finite element calculations with PLAXIS for forest soil loaded by a tyre. This includes situations with and without reinforcement by tree roots. The reinforcement effects are, a.o., decrease of wheel rut depth and rolling resistance, decrease of damage to soil structure by the wheel load, and as a negative effect, damage to the tree root system. The magnitude of these effects depends on a number of parameters: stiffness and strength of the tree roots; soil mechanical properties like cohesion, angle of internal friction, compression index, preconsolidation stress; depth of a hard sublayer (if present); distance between vehicle and tree; rooting pattern; adhesive and frictional properties of the soil–root interface; tyre load and contact surface. The presented calculation results, which are based on realistic input data, show the sensitivity of the reinforcement effect to the listed variables.

Noise emission, friction and rolling resistance of car tires: summary of an experimental study

Abstract: Car tires are supposed to be constructed for safe,economical, pleasant and environmentally friendlydriving. Three performance measures that would quitewell represent the major operational character ...

Low rolling resistance tire for vehicles having a composite tread

Abstract: A low rolling resistance tire ( 1 ) for vehicles is described which comprises at least one belt layer ( 7 ) coaxially extending around at least one carcass ply ( 3 ), a composite tread ( 10 ) coaxially extending around the belt layer ( 7 ) and comprising a radially outer layer ( 12 ) and a radially inner layer ( 11 ), wherein the ratio between the modulus of elasticity E' at 70° C. of the radially inner layer ( 11 ) and the modulus of elasticity E' at 70° C. of the radially outer layer ( 12 ) is comprised between 1.1 and 3, and the ratio between the value of tangδ at 70° C of the radially inner layer ( 11 ) and the value of tangδ at 70° C. of the radially outer layer ( 12 ) is lower than 0.8. Advantageously, the tire ( 1 ) achieves a better compromise between the characteristics of rolling resistance, handling and comfort with respect to what is obtainable from known tires for the same type of use.

Composition for the treatment of friction pairs

Abstract: The present invention relates to the lubricant grease compositions, in particular to the compositions for the treatment of friction pairs, and can be used in the machine building for the treatment of friction units, and also during the exploitation of different mechanisms and machines for prolongation of interrepair time or for damage control (repair-restore operations). The basis of the invention is the improvement of the composition for the treatment of friction pairs, including metal and non-metal oxides, in which, as a consequence of the use of the products of dehydration of such hydrates, which in the stable state contain oxides from the series of MgO, SiO2, Al2O3, CaO, Fe2O3, K2O, Na2O in its composition, is provided by the formation of the stable state on nanodispersed oxide structures, which minimize the resistance to displacement and area of contact surfaces of friction pairs, and transfer any form of friction in the rolling friction, and at the expense of that, strengthening of friction pair surfaces and decrease of friction coefficient are reached; working-technical conditions of machines and mechanisms are improved. The use of the compositions according to the offered technical decision provides to receive the stable results, manifested by hardness and wear resistance increase, friction coefficient decrease, improving of technical-economical characteristics of the machines and mechanisms.

Rolling bearing and method of machining rolling element of the bearing

Abstract: In rolling bearings used in a circumstance undergoing high temperature, large loads and large vibrations, it has been known that early flaking phenomenon more tending to occur in the rolling element than in the bearing ring. In view of the above, according to the present invention, a rolling element with improved rolling contact fatigue resistance can be obtained while keeping hardness by devising a combination of mechanical surface hardening treatment and a heat treatment to a surface of a rolling element. A rolling bearing of long life can be provided even under large loads and large vibrations by incorporating the rolling element. That is, according to the present invention, a surface hardening treatment is applied after quenching and tempering to a rolling element to provide a surface with a residual compressive strength and, subsequently, secondary tempering and then finish grinding are applied to make the amount of residual austenite in the surface layer to 0 to 15%, the final residual compressive strength value to −600 to −1200 MPa and a working strain relieving degree to 10 to 60%. This can provide a long life rolling bearing under large loads and large vibrations.

Rotation transmission device with built-in one-way clutch

Abstract: PROBLEM TO BE SOLVED: To improve lock performance of a one-way clutch and durability of respective parts. SOLUTION: Grease suitable for sliding friction is sealed in this one-way clutch 10a. While, grease suitable for rolling friction is sealed in support bearings 9a and 9a arranged on both sides of this one-way clutch 10a. The purpose is attained by using the grease suitable for behavior of the respective parts at operation time.

Linearly guiding unit

Abstract: PROBLEM TO BE SOLVED: To reduce the sliding resistance of a slider by supplying a lubricant contained by in lubricant-containing member to the raceway groove of a raceway rail through a rolling element slidably contacting with the lubricant- containing member. SOLUTION: A lubricating device 15 contains a lubricant-containing member 43 within a case 21 to be mounted on a slider or the like, and rotatably holds a lubricating rolling element 40 by a rolling body holding part 33. The lubricant 41 impregnated in the lubricant-containing member 43 is supplied to the raceway groove 4 of a raceway rail 2 through the surface of the lubricating rolling element 40 slidably contacting with the lubricant-containing member 43 to lubricate the raceway groove 4 and a raceway grove for rolling a rolling element within the slider. Since the friction resistance of the rolling element 40 in traveling on the raceway rail 2 is rolling resistance, the slider smoothly travels with small sliding resistance.

Method for designing tire, method for designing mold for vulcanization of tire, manufacturing method of mold for vulcanization of tire, manufacturing method of tire, optimization analysis apparatus for tire, and storage medium recording optimization analysis program of tire

Abstract: PROBLEM TO BE SOLVED: To design a tire exhibiting sufficient abrasion resistance, performance on a wet road surface, and rolling resistance by suppressing abrasion and deterioration of performance on the wet road surface and the rolling resistance caused by inequality of ground pressure for a tire having continuous grooves along the circumferential direction. SOLUTION: For a tire having continuous grooves 41 and 42 along the circumferential direction, performance related to tread pressure properties of ribs 31 to 33 represented by abrasion at an early stage of ends of ribs 31 to 33 is taken as an objective function. A circular arc shape added to the ends of the ribs 31 to 33 is taken as a design variable. A design variable offering an optimum value for the objective function meeting a constraint condition is calculated while predicting a tire performance in an environment the tire is used actually in order to design the tire based on the calculated design variable.

Using a Friction Observer to Compensate Friction Force at Head Actuator Bearings of Magnetic Disk Drives.

Abstract: Under micro-displacement, pre-rolling friction at the head actuator bearings of magnetic disk drives has spring and damper characteristics. To compensate this friction, a force observer designed on the basis of a friction model of spring and damper characteristics has been developed. This observer enables precise estimation of the friction force at head actuator bearings and eliminates the influence of pre-rolling friction. Hence the dynamic property of the head actuator recovers its pure inertia property, which is represented by 1/s2 in the frequency region below 100Hz. To compensate the friction force and recover its pure inertia property is important to apply a feed-forward control because it is designed on the basis of the model of the head actuator. By simulation and experiment, it is confirmed that this control method enables the head actuator to recover the inertia property in the low-frequency region.

Vehicle weight-detecting device

Abstract: PROBLEM TO BE SOLVED: To provide a vehicle weight-detecting device for achieving accurate control based on a calculation result by constantly calculating the weight of a vebicle accurately regardless of the driving state of the vehicle. SOLUTION: The following expression for obtaining vehicle weight W is set, where the weight is calculated from gravity acceleration (g), drive force F of the vehicle being generated by engine torque, air resistance R1 operating on the vehicle, inertial weight Wr that the rotary part of the power transmission system of the vehicle has, actual acceleration αv obtained from the vehicle speed, road slope sin θ of a road where the vehicle is driving, and a rolling resistance coefficient μ of a tire. When the absolute value of the denominator of the expression is equal to or more than a specific value (YES in step S4), and the amount of influence to the denominator of an error included in the actual acceleration αv is small, the calculation processing for the vehicle weight W is executed (step 6). COPYRIGHT: (C)2001,JPO

Genetic algorithm (GA) based modeling of nonlinear behavior of friction of a rolling ball guide way

Abstract: We propose a new dynamic model for friction. The nonlinear behavior model can be used for modeling Coulomb friction, viscous friction and Stribeck effect, and can also be used to study the nonlinear behavior of elastic deformation. The frictional force does not cause disturbance in the accelerated motion, but lends a support. The model curve is not symmetrical with zero velocity. Properties of model that are relevant to control design are investigated by analysis and simulation. Genetic algorithm has been used for tuning the model. Tuning results show that the proposed model is more accurate than conventional models.

Measuring apparatus for dynamic torque of rolling bearing

Abstract: PROBLEM TO BE SOLVED: To obtain a measuring apparatus by which the dynamic torque of various rolling bearings can be measured precisely under various conditions by providing a static-pressure bearing which prevents a housing from being displaced to the axial direction and which permits the housing to be displaced to the circumferential direction. SOLUTION: In a rolling bearing 1a as an object to be measured, its outer ring 2a is fitted internally to a housing 3a so as to be fixed, and its inner ring 4a is fitted externally to a rotating driving shaft 5a so as to be fixed. A static-pressure bearing 6a is installed in the lower part of the housing 3a, and the weight of the housing 3a and that of the rolling bearing 1a are supported and borne. A pair of static-pressure bearings 22, 23 are installed on both sides in the axial direction of the housing 3a in order to prevent the housing 3a from being displaced and moved to the axial direction. When the dynamic torque of the rolling bearing 1a is measured, a radial load is applied to the rolling bearing 1a via the static-pressurebearing 6a and the housing 3a, and the inner ring 4a is turned and driven by the rotation driving shaft 5a. Then, a dynamic torque which is applied to the outer ring 2a is measured on the basis of the rolling resistance of a plurality of rolling bodies which constitute the rolling bearing 1a.

Rubber composition and method for producing the same

Abstract: PROBLEM TO BE SOLVED: To obtain a rubber composition improved in wet braking and rolling resistance and good at abrasion resistance. SOLUTION: This rubber composition is obtained by including 50-90 pts.wt. diene-based resin and 50-10 pts.wt. rubber gels having 16-150 toluene lubricated index (wherein a total of 100 pts.wt.). COPYRIGHT: (C)2001,JPO

Friction and Wear at Tractive Rolling of Cylinders

Abstract: Based on the fundamentals of tractive rolling contact mechanics, a method is described which is suited for calculating traction coefficients. Both the deformation and the adhesion component of friction are taken into consideration. It is demonstrated that the maximum traction coefficient is not a constant, but takes different values under various load conditions as a result of changes in the micro-geometrical pattern. Using the load-specific maximum traction coefficient it is possible to predict a fairly accurate value of the traction coefficient of the tractive rolling contact. In addition, the results of wear investigations are reported, and an approach to apply test results to the real wheel/rail system is described. The tests were carried out with materials common in railway design; in particular, R7 wheel material and standard-grade 900A rail material were used. During the tests the normal force and the creep were varied. Wear investigations conducted on the test machine revealed that the relationship between friction work and wear volume is an almost linear function.

Road surface state identification device for vehicle

Abstract: PROBLEM TO BE SOLVED: To discriminate between a sandy road and a pressurized snow road SOLUTION: An estimation value θ-hat of a pseudo maximum friction coefficient equivalent to an inclination of μ-s characteristic curve in the periphery of a slip ratio O based on a wheel speed estimation error ew and a car body speed estimation error ev and an estimation value μr-hat of a rolling resistance coefficient is calculated based on the car body speed estimation error ev so that the road surface state is estimated based on the pseudo maximum friction coefficient estimation value θ-hat and the rolling resistance coefficient estimation value μr-hat The sandy road and the pressurized snow road having the similar road friction coefficients can be thus discriminated COPYRIGHT: (C)2001,JPO

Rolling inserting contact mechanism

Abstract: The utility model relates to an insertion type contact mechanism of a low-voltage switching device used in electric power distribution systems. The rolling insertion type contact mechanism is composed of a moving contact, a static contact and the pressure springs; rolling conductors are arranged between the moving contact and the static contact. The utility model alters traditional modes of the insertion type connection of direct contacts of the moving contact and the static contact; rolling conductors are used for separating the moving contact from the static contact; thereby, the original slide friction is converted into rolling friction in the process of the insertion type connection; furthermore, the needed insertion force is reduced greatly, realizing the aim of switching high currents in a convenient and labor saving mode.

Dynamics of a rolling disk and a single wheel robot on an inclined plane

Abstract: The dynamics of a rolling disk and a single wheel robot on an incline are derived and established respectively. The condition of rolling up is addressed. If the condition of rolling up is violated, a methodology of tracking is proposed. The system is stabilized around the position perpendicular to the surface. Simulation results are also provided.

Modified Lagrange Method to Analyze Problems of Sliding and Rolling

Abstract: A modified Lagrange method to analyze problems of sliding and rolling is presented. The method is based on modeling the friction as a process of collisions between the sliding and rolling body, and particles of the surface on which it slips and rolls. The process of collisions does not need to describe the exact friction process. Instead it can represent another equivalent mechanism of loss of energy of the body due to sliding and rolling. The function that describes the rate of increase of the kinetic energy of the particles, as a result of the collisions, plays a major roll in the modified Lagrange equations. Cases of isotropic and anisotropic friction can be modeled. Three examples of using the method are presented. It is shown that when an infinitely rough surface is assumed, the classical equations for nonholonomic constraints of rolling without sliding are obtained. Lagrange multipliers that appear in these equations obtain direct physical meaning and the mechanism behind the constraint becomes clear.

Determination of the dynamic angle of the bearing's rolling element location and of its influence on the loads and rolling friction

Abstract: A model for determination and analysis of bearing external radial and axial load distributions per individual rolling elements and a model for determination of the resistance to motion of rolling friction, accounting for rolling element locations during the bearing track motion with respect to the direction the bearing radial load resultant vector acts, are presented. A dynamic angle of the rolling element location has been defined as well. The models have been developed to determine values of bearing load distribution parameters, individual rolling element loads, and resistances to rolling motion of bearings and rolling bearing systems, as well as to analyze distributions and values of the radial and axial stiffness of rolling elements, bearings, and kinematic pairs as a function of the bearing rolling element distribution and the direction along which the bearing radial load resultant vector acts. The proposed models have been built to carry out analysis of the resistance to motion of rolling kinematic pairs of industrial robot manipulators. Slow-speed and short-period motions of rolling bearings have been assumed as a characteristic type of motion of rolling kinematic pairs in manipulators. © 2000 John Wiley & Sons, Inc.

Actuator for vehicle steering systems is connected into the low torque region of the steering system via a friction wheel transmission with at least one biased friction wheel

Abstract: The actuator (1) is connected into the low torque region of the steering system via a friction wheel transmission (4-7). At least one of the friction wheels in the friction wheel transmission is biased and the axes of rotation of the friction wheels intersect at an angle, preferably approximately 90 degrees.

The control of wheel/rail rolling noise at the source

Abstract: Wheel/rail rolling noise, which dominates on straight track in the absence of wheel flats and rail joints, is produced by the fluctuating forces generated in the contact zone by the small scale roughness on the running surfaces of the wheel and rail. Controlling rolling noise at the source involves reducing this roughness itself or modifying the interaction between wheel and rail in the contact zone so as to reduce the interaction forces. Here, using analytical models of the interaction in the contact zone, we examine a number of alternative approaches to reducing the roughness excitation. The approaches include, wheel and rail smoothing, resiliently treaded wheels, wheel profile modifications and the use of fluid films. While some of the approaches offer the potential for reducing rolling noise by 5 to 10 dB, there are a number of practical problems to be overcome. The estimated acoustic performance and potential implementation problems of each treatment are discussed.