Wear depth calculation and influence factor analysis for groove ball bearing

Based on Hertz contact theory and load distribution, the formulas for contact stress cycle times, slip distance and wear depth measurements are derived, and the influences of load, curvature coefficient, roll body diameter and friction coefficient on the contact region wear depth and distributions are thoroughly analyzed. The results show that the wear depth is zero at the pure rolling point and the long half-axle terminals of contact ellipse, and reaches maximum value near by the long half-axle terminals of the contact ellipse, and further shows that the wear depth increases with increase of the load and friction coefficient, however decreases with increase of the curvature coefficient and roll body diameter.

Source Location of Cracks in a Working Roll of the Temper Mill with Acoustic Emission Technology

The application of the temper mill is mainly to improve the mechanical property of strip and to rectify the shape of strip. The working roll of a temper mill is often running with alternating load that prone to lead to faults such as wear, crack and spalling, which cause severe quality problems in the production of strip steel. In order to gain the information of crack's location and depth, the proposed method employs two circles of AE sensors along the direction of the roll body and use static pressure as external loads together with time-of-arrival localization method to detect the exact location of the roll cracks. The positioning results confirmed the validity of the proposed method with the post-repair grinding data. The advantage of this detection method is not requiring the full roll body scan point by point. With only one layout of the sensors, the method can detect the crack location with high efficiency and good real-time property.

Four-High Mill with Statically Determinate Characteristics of Micro Displacement of the Components

The theory of micro dimensional behavior on rolling mill is used for a typical 450 mm hot plate four-high mill. A statically determinate device is adopted on the back-up roll system to adapt to the micro-dimensional deflection. We replace the traditional single base with the force divided base for the rolling load. To make the rolls parallel, a worm-screw device is set in the chock, with a clearance between the chock and the stand window to allow convenient roll replacement and retain a thermal expansion space. In the new mill, the center line of the roll body is constant when the rolling is stopped or running. It can be predicted that the mill will be strengthened two times and the roller bearing life will be prolonged ten times.

An Investigation Into the Design of Hollow Accumulator Rolls Using Finite Element Analysis

Accumulator systems consist of a series of accumulator rolls, arranged either vertically or horizontally, used in many sheet processing lines for the purpose of storing up strip. Literature on roll design for this particular type of roll is scarce. Much of the present design theory is based on a static analysis assuming the entire contact load from the strip is uniformly distributed over the roll. A previous paper done on this subject focused on modeling the roll using finite element analysis (FEA) assuming this uniform pressure load on the roll. The purpose of this work was to incorporate non-linear contact elements between the strip and the roll body in a finite element analysis. This would allow the software to distribute the load from the strip to the roll, taking into account friction and contact losses. Once accomplished, this load was placed on various roll design configurations, of which included variation in the number of roll stiffeners and the thickness of the roll body and the end plates. These results were also compared to the previous uniform pressure FEA in order to assess the validity of the uniform pressure assumption. Based on these results, a roll design methodology is presented.

Accumulator Roll Analysis Using the Finite Element Method

The purpose of this study was to develop a method to analyze various designs of non-driven accumulator rolls using a static finite element software package. This would allow the engineer to determine how the various components of the roll design contribute to or lessen the deflection of and stresses in the roll body when it is loaded by sheet metal passing over o under it. The method outlined is intended mainly for use when an advanced dynamic finite element package that incorporates contact elements is not available and when a comparison of various roll designs is desired. First, an approximation of the pressure on the roll body caused by the force of the sheet metal as it wrapped over or under the roll was determined. Then using the finite element package ALGOR, an FEA model of a standard accumulator roll design was loaded with this pressure and the stresses and deflections were calculated. Next, components of this basic roll design were varied in the FEA model. These were the location of the stiffeners and the thickness of the roll body, the end plates, and the stiffeners. A comparative approach was then used to assess the impact each of these variations in roll design had oh the deflection of and the stresses in the roll.