Conical Rollers Research Articles

The Ring’s Axial Deformation Control Method of Vertical Hot Ring Rolling Process

Axial deformation of the ring during the traditional vertical hot ring rolling (VHRR) process has a considerable effect on the ring products’ quality. In this paper, the ring’s axial deformation of VHRR process of three different rolling modes, that is, open-die mode, close-die mode and open-die mode with conical rolls like the radial-axial ring rolling (RARR) process is analyzed. Three groups of 3D coupled thermo-mechanical FE models of VHRR process are established in software ABAQUS, and the axial deformation and the width spread of the rings are studied in detail. Finally, a special conical roll device was designed and equipped on the traditional VHRR mill, and series of VHRR experiments are conducted, the results of both simulation and VHRR process show that the formed rings utilizing open-die rolling with a special pair of conical rolls has lower axial deformation, smoother end surface and higher precision than the formed rings utilizing open-die rolling and close-die rolling. The research results can supply an effective approach to axial deformation control of traditional VHRR process.

Design Method of Calibrating Curve and Its Effects on Conical Ring Rolling Process for TC4 Titanium Alloy

Design Method of Calibrating Curve and Its Effects on Conical Ring Rolling Process for TC4 Titanium Alloy

The Development of Database System of Parameter and Coefficient for the Common Shafting Parts

This article illustrates with the criterion of the common shafting accessorys design, using the Visual C++ and the Access to primarily set up the parameters and coefficients database of the shafting accessories, which are mostly the gear and the conical roller gearing. Setting up its function as demanding, appending and deletion, etc. Making the data processing for mechanical design and other fields conveniently. Through this research and exploitation, It can account for setting up the parameters and coefficients database of the standard accessory is necessary and really count for engineering.

New Method Using Piezoelectric Jerk Sensor to Detect Roller Bearing Failure

An acceleration sensor is usually used to examine for roller bearing damage. It is difficult, however, to detect abnormal vibration and examine for roller bearing damage when rotation speed is low. The final target of this study is to establish a bearing damage diagnosis system based on the piezoelectric jerk sensor we developed, which can be used for both low- and highspeed rotations. For this purpose, this paper aims to identify the features of an abnormal vibration detection signal at a low rotation speed, propose a new roller bearing damage diagnosis method that uses the features, and clarify the validity of the method. Experiments are conducted to analyze a scratch purposely made on the outer ring of a conical roller bearing that rotates at the low speeds of 10 or 40 rpm. The results verify the advantages of using the jerk sensor for the bearing damage diagnosis and the validity of the method proposed in this paper.

A gamma Bayesian exponential model for computing and updating residual life distribution of bearings

Residual life estimation occupies an important place in modern mechanical design and condition-based maintenance programs. Condition monitoring information can reflect the health status of the individual device, and the effective use of this information can help continuously predict the individual residual life. In this study, an exponential degradation model is developed to describe the degradation characteristics of devices for residual life estimation. This model is based on a gamma-prior Bayesian updating approach and an acceptance–rejection algorithm. With the gamma distribution representing the degradation rate differences among individuals, the real-world data can be described flexibly. By aid of Bayesian updating approach, the model can be updated with both the historical data and real-time monitoring signals. Furthermore, on the basis of the updated model and by means of acceptance–rejection algorithm, the residual life distribution can be computed without redundant computation. Consequently, the residual life can be estimated using the results of the residual life distribution. Finally, the proposed method is applied to real-world vibration-based degradation signals resulting from the accelerated fatigue testing of conical roller bearings. The results show that this method can avoid redundant computation and effectively estimate and update the bearing’s residual life. Therefore, the engineering value and general application of this novel method has been validated.

Technological solution to profile and generate the teeth of central gear for precessional gear drives

The transmission based on precessional gear pairs, mostly used for rotation speed reduction, has some important advantages relative to the common gear drives, such as the capability to produce very low transmission ratios, or the high loading capacity/dimensions ratio (due to the fact that all the teeth of a precessional gear pair are simultaneously in contact during its functioning). One among the likeliest constructive solutions for the precessional gear pair uses a satellite built with conical rollers. However, its practical use is restricted by the difficulty to realize the central gear teeth machining without using special and relative complicated devices. This paper introduces a technological substitutive profile for the central gear tooth, which enables the use of a simpler and more productive method for working it, without bringing major negative consequences regarding the teeth contact correctness or the drive loading capacity. The profile was found by analyzing the contact surface and the pressure angle evolution during the contact between conjugate teeth. The paper also presents technological solutions to generate the new tooth profile by milling it with a disk-tool or an end-mill cutter, together with methods to profile the required tools.

Investigation of non-kinematic conical roll bending process with conical rolls

Although high quality cones can be produced with kinematic conical roll bending due to the non-slide condition between the conical rolls and the plate, the process flexibility is limited because the conical rolls cannot be reused to produce cones of different cone angles. In this paper, a non-kinematic three-roll bending process is proposed to reduce manufacture costs by reusing existing conical rolls. In this process, an attachment is added to the top edge of the plate to obtain required circumferential velocity as the top/bottom radius ratio of the desired cone is smaller than the rolls. The top sides of the conical rolls slide on the plate to reduce the local velocity near the top edge and an appropriate velocity near the top edge of the plate can be obtained by adjusting the friction coefficients between the rolls and the plate. This flexible process can provide performance similar to the kinematic conical roll bending process. The process modeling is based on the finite element method under ANSYS/LS-DYNA environment. A relation between the gap size of the bent cone and the friction at the plate/attachment contact interface has been investigated by using numerical simulations. The simulation results give a well bent cone compared with an ideal cone.

Study of Shaft Drive Continuously Variable Transmission (5th Report, Driving by Backup Disk for Increase of Torque Capacity)

A novel CVT mechanism (a shaft drive CVT) was developed by the authors. In the mechanism, the input and output shafts with conical disks are parallel and an idler shaft with conical rollers at both ends is placed perpendicular to the input/output shafts. This idler shaft transmits torque from the input shaft to the output shaft and its linear motion causes the speed to vary by changing the contact point between the input/output disks and the idler roller. The backup disks are connected to the input/output shafts and do not contribute to power transmission. In this paper, we propose a mechanism to transmit torque between the backup disks and input/output shafts to enlarge the amount of transmitted torque. A gear train was added behind the backup disk for new torque path. Its effect is examined and confirmed by the experiment using the prototype CVT. The efficiency of 3 percentage points was improved and the torque capacity became twice by the contribution of backup disk.

Three-stage process for improving roll bending quality

Continuous pyramidal three-roll bending process has the simple configuration. However, two planar zones exist near the leading and trailing edges after a conical roll bending. This paper proposes a three-stage process to improve the geometrical quality of a bent cone for providing an alternative process for the manufacture of the crowns of Francis turbines for hydro plants or the towers of wind power plants. The process was simulated under the commercial software LS-DYNA with an explicit scheme and ANSYS with an implicit scheme. The geometrical quality of the bent cone was improved after the final stage of the process.

Sideways Movement of Strip in In-Plane Roll-Bending Process with Conical Rollers

As a result of unequal reduction, the sideways movement of the strip at the entry is occurred in in-plane roll-bending process with conical rollers. This will reduce the shape quality of the formed ring. To control the sideways movement, FE simulations with applying unilateral and bilateral guide planes are carried out by employing ABAQUS/Explicit code. The results show that, the strip moves towards the bottom end and scratches with guide plane at the trailing end if applying unilateral guide plane; the sideways movement can be controlled effectively with circularity of 0.993 and maximum deviation ratio of 12.5% for the formed ring if applying bilateral guide planes.

Complete modeling and parameter optimization for virtual ring rolling

Virtual manufacturing, usually consisting of complete modeling and optimization, of a manufacturing process has recently become one of the research trends in the area of process designing and selection. With the aim to realize complete modeling of a ring rolling process, a complex actuation mechanism model of a heavy radial–axial ring rolling machine has been established in this study. Moreover, a self-modified computer program for controlling the real-time movements of two guide rollers and two conical rollers in a ring rolling process has been developed. An optimization objective function has been proposed for saving the rolling time, in which the slip rate is regarded as the state variable. With this function, the virtual ring rolling process for producing a titanium alloy ring with a rectangular section has been successfully conducted using the finite element method. The simulation results are in good agreement with the experimental findings. Thus, the feasibility of the proposed method has been demonstrated. The computational result also reveals that the proposed optimization method can reduce the rolling time by about 28%.

Numerical study of non-kinematical conical bending with cylindrical rolls

Although desired cones can be manufactured by kinematical conical roll bending, less manufacturing cost is still largely required. This paper presents the modelling and simulation of non-kinematical conical roll bending process with cylindrical rolls. Such process is achieved by using attachments to reduce the velocity on the area close to the top edge of the plate. In contrast with a kinematical conical roll bending machine, the driving outer rolls of a non-kinematical conical roll bending machine are allowed to slide on the plate close to the top edge. The modelling is based on finite element method under ANSYS/LS-DYNA environment. The bent cones obtained from numerical simulations compare well with the desired cones. Numerical simulation investigations show that the adaptive capacity of the model is available within a range of the top–bottom radius ratio of the desired cones between 0.44 and 0.8.

Performance of a low-spin disk for a shaft-drive continuously variable transmission

A novel continuously variable transmission (CVT) mechanism (a shaft-drive CVT) was developed by the present authors. In the mechanism, the input and output shafts with conical disks are parallel and an idler shaft with conical rollers at both ends is placed perpendicular to the input—output shafts. This idler shaft transmits torque from the input shaft to the output shaft and its linear motion causes the speed to vary by changing the contact point between the input—output disks and the idler roller. In this paper, the use of a disk with a concave shape is proposed in order to decrease the amount of spin caused by the change in the contact point, because the spin has an adverse effect on traction contact performance and is responsible for an increase in power loss. The design procedure of the novel concave disk and the roller is discussed and their effect is evaluated using a prototype CVT. The speed efficiency was improved to 1.6 points in the case of a transmitted power of 0.6kW.

Rolling in four-roller grooves

814 In comparison with two-roller grooves, multiroller grooves have a series of undoubted advantages [1]. In particular, they permit increase in the rigidity of rolling cells and hence the dimensional precision of the rolled product, reduce broadening and improve the extrusional properties of the grooves, change the stress state in the deformation source so that it more closely resembles omnidirectional compression, and consequently increase the plasticity of the rolled metal. Broad introduction of multiroller grooves is hindered by the complexity of the rolling-cell structure and the need for long transmissions when all the rollers are driven by a single motor. The design and maintenance of the cells is somewhat simplified when mushroom-shaped cantilever rollers are employed, but this reduces roller rigidity. Free play arises in the drive transmissions as a result of wear, with accompanying asymmetry of the reduction zone and flexure of the end of the strip at the beginning of rolling. To simplify cells with multiroller grooves and eliminate free play, we may install an individual hydraulic drive for the rollers (Russian Patent 2 087 220) [2]. To increase rolling accuracy, it is expedient to use conical rollers in multiroller grooves. The configuration of square and round grooves for four-roller operation in the round‐square‐round system is shown in Fig. 1. All the rollers are installed in a cantilever mode, in individual suspension, and may be displaced axially (Fig. 1a), with change in the dimensions of the square groove, which remains closed. The aperture of the end gaps in this case is determined solely by elastic deformation of the suspension and the cell housing. An undoubted benefit of grooves formed by conical barrels is decrease in the total transverse pressure of the metal on the roller. In rolling, besides the transverse component, there is a longitudinal component P / (where P is the total force of the metal on the roller) and an additional bending moment due to the force parallel to the roller axis. The roller’s supporting bearings experience these additional forces and torques. With rational suspension design, the rigidity of the cell is increased somewhat in comparison with analogous cells in which the multiroller groove is formed by cylindrical rollers.

Rotary extension of anisotropic pipe blank with wall thinning

Rotary extension is being increasingly used in the manufacture of thin-walled axisymmetric parts. Theoretical study of this process with thinning is complicated by local deformation and by the three-dimensional stress and strain states of the material in the plastic region [1‐4]. The pipe blank subjected to rotary extension is characterized by anisotropy of the mechanical properties due to the material and the manufacturing conditions. Anisotropy of the mechanical properties of the material may have both positive and negative effects on the stability of pressure treatment of metals [5]. Consider the rotary extension of a thin-walled pipe blank made of anisotropic material, by a direct method (Fig. 1); conical rollers are employed (conical angle α ro and strain e = 1 ‐ t co / t 0 ). In one turn of the blank, the roller moves by an amount equal to the working supply S . With supply of the roller by S , the actual supply will be S ac = St co / t 0 . Plane deformation along the axis is assumed here. On the basis of geometric considerations, it is simple to determine the maximum contact angle θ b of the roller with the blank [4]

Contact stresses in conical rollers

In this paper, the pure rolling contact stresses in conical rollers under normal loading are studied. The existing analytical expression for pure rolling contact pressure in uniform cross-section cylinders is modified to determine the contact area, the contact pressure, and its distribution in conical rollers under normal loading. The Hertzian contact stresses are determined for the modified pure rolling contact pressure distribution. The theoretical results are compared with the finite element analysis using ABAQUS, for different vertex angles, materials, and loads. The results of the theoretical model are found to be consistent with the finite element simulations in predicting the contact pressure, the distribution, and the contact stresses in conical rollers.

FEM dynamic simulation and analysis of the roll-bending process for forming a conical tube

Abstract A general simulation model is developed to study the dynamic process of roll plate bending using finite element method (FEM). In this work, the continuous three-roll pyramidal bending configuration with conical rolls is used to bend a thick plate into a conical tabular shape. We present the kinematic relationship existing between rolls and workpieces, the geometrical setup and the finite element model. The dynamic forming process, going from the initial plate to the finished conical shape, as well as the stress variation of the workpiece over time, can be visualized during the course of the simulation. This 3D simulation is based on the elastic–plastic explicit dynamic finite element method under the ANSYS/LS-DYNA environment. A numerical algorithm is also developed to quantify the dimensional and geometrical accuracy of the produced conical shape with respect to the desired truncated cone. The Levenberg–Marquardt nonlinear algorithm is implemented in this step in fitting the point clouds generated by the FE software into a least-square cone, which is used for comparison with an ideal one. Parametric studies are carried out to investigate the effects of various parameters, including friction coefficient, on the quality of the final shape, based on simulation results. The required forces and torques in terms of plate thickness and roll configurations are illustrated. This work is conducted in an attempt to study the feasibility of using the roll-bending process with thick plates and to provide engineers with a convenient numerical tool for optimizing process parameters.

Development of the profile ring rolling process for large slewing rings of alloy steels

In this study, a profile ring rolling process for large slewing rings of alloy steels is developed. A profile ring with a round groove located asymmetrically on the outside is rolled. The process is simulated by finite element method. General-purpose commercial finite element analysis software, MSC.SuperForm, is used. Experiments are carried out at an industrial ring rolling machine and compared with the analysis. By choosing the method that the height in the axial direction of the initial ring blanks is set higher than products and lowered by using conical rolls during the process, it is attempted to develop process to make a large slewing ring at a single ring rolling operation. To do this, the process is analyzed using the finite element analysis method and an experiment to make the real profile ring is carried out. In the case that the round groove on the outside is located at upper side, the position of the round groove moves downward and sidewall tilts. This phenomenon is predicted relatively well at the finite element analysis. It is recommended that the round groove on the outside is located at lower side.

Geometric design of a pinion with two circularly arrayed conical teeth for roller drives

This article presents a mathematical model and geometric design algorithm for a new type of roller drive. The pinion has conical teeth in two circular arrays instead of one. This work is based on coordinate transformation and envelope theory, from which the equation of meshing of the cycloid drive is derived. The pinion profiles are the equidistant curves of the epicycloid profiles except the contour of the pinion conical tooth holes. Although there are twice as many pinion teeth as conventional rollers, their speed ratios are identical. This approach can design roller drives in which the pinion has two circular arrays of conical and cylindrical rollers. On the basis of these results, the corresponding solid modelling is constructed by CAD. Four examples are presented to demonstrate the feasibility of this approach. These examples can be a useful reference as a design case for other tooth profiles.

Analytical and experimental study on the spiral marks of the rolled product during three-roll planetary rolling processes

In this study, the effects of various rolling conditions, such as inclined angle, offset angle, roll shapes, etc., upon the depth of the spiral marks on the surface of the rolled product and the rolling forces are discussed numerically by the finite element method. Experiments using a self-designed testing machine with work-rolls of three different kinds of roll shapes were conducted. The depth of the spiral marks was measured. From the comparisons between the analytical and experimental results, it is known that a smoother surface on the rolled product can always be obtained with convex-shaped rolls. Whereas, prominent spiral marks probably appear for two-stage conical rolls and spherical-headed rolls under an ill-set rolling condition. These analytical and experimental results can offer useful knowledge for the design of the roll shapes and the pass schedule during three-roll planetary rolling processes.