Key Groove Research Articles

Fracture cause analysis of the extruder’s shaft and geometry optimization of the spline

The article is devoted to increasing of the durability of technological equipment elements, forecasting of the resource and diagnostics of failures of the technical system. The basic regularities are analyzed and causes of the failure of the extruder’s working body shaft are determined. For torque values M = 40.74 - 64.37 N·m and of the extruder’s working body shaft, the stress-strain state of the contact surfaces of the keyhole of the extruder’s shaft is calculated by the method of three-dimensional finite element modelling. The maximum values of the stress intensity σint(max), which arise on the edge of the key groove, are calculated. It was established that an increase in the distance of the key groove to the fillet of the working body shaft by 2.0 mm leads to a decrease in the maximum stresses on the edge of the key groove by 15.72%. The results of the research allow optimizing the geometry of the shaft.

Fatty-acylation target sequence in the ligand-binding domain of vertebrate steroid receptors demarcates evolution from estrogen-related receptors

Present-day nuclear receptors (NRs) responding to adrenal and sex steroids are key regulators of reproduction and growth in mammals, and are thought to have evolved from an ancestral NR most closely related to extant estrogen-related receptors (ERRs). The molecular events (and ligands) that distinguish steroid-activated NRs (SRs) from their inferred ancestor, that gave rise to both the ERRs and SRs, remain unknown. We report that target sequences for fatty-acylation (palmitoylation) at a key cysteine residue (corresponding to Cys447 in human estrogen receptor ERα) in helix 8 of the ligand-binding domain accurately demarcate SRs from ERRs. Docking studies are consistent with the hypothesis that palmitate embeds into a key groove in the receptor surface. The implications of lipidation, and of potential alternative ligands for the key cysteine residue, for receptor function and the evolution of SRs are discussed.

Experimental and analytical approach of fatigue behavior of stepped CK45 shaft with adjacent key groove

Stress concentration areas such as keyways and shaft steps appear frequently used in mechanical engineering design. Areas like these are characterized by difficulties in accurately predicting part operating lifetime, often driving into premature fractures causing unplanned machine stoppages. The impact of such areas in engineering design is assessed with the aid of the “k-factors”, however, these factors cover only the effect of a single notch on the whole structural element. In mechanical engineering design it is common for multiple stress concentration areas to coexist adjacently, where the existing analytical theory cannot be used to assess the effect. The effect of adjacent step and keyway on a DIN CK45 shaft is investigated in the present paper. For this purpose, a DIN CK45 steel shaft specimen with a standardized keyway and a diameter-step has been tested under rotating bending to investigate the interaction of two distinct stress concentration areas. Analytical and numerical methods have been used to support the conclusions.

Innovative Tool Coatings for Increasing Tool Life in Milling Nickel-coated Nickel-silver Alloy

In the automotive market, there is a strong interest for the production of sidewinder keys made of Nickel-coated Nickel-Silver alloy. The Nickel coating improves wear resistance and brightness of the key, nevertheless it reduces the machinability and the tool life when milling the key groove is short. In this work, several innovative tool coatings were applied on conventional mills to enhance the machinability of Nickel-coated Nickel-Silver alloy. Tool life and burr formation obtained with the tested tools were investigated and discussed. Some of the coatings proved to be very promising for this application thank to their excellent tool life. Specifically, the PCD tool was the most interesting since the tool life was significantly longer than conventional carbide tool.

Allowable Height Difference between Adjacent Monoliths with Spherical Surface Key Groove in Transverse Joints

The calculation method of the minimum aperture of transverse joints with spherical surface key groove was introduced in this study. Based on the computation theory of allowable height difference between adjacent monoliths proposed by Bofang Zhu, the analytical model of allowable height difference of Xiluodu arch dam was established with consideration of the effect of main factors on the transverse joints deformation, including the temperature, autogenous volume deformation, self-weight and foundation. After the horizontal and vertical deformations of transverse joints was required, according to the form of spherical surface key groove, the aperture of each part of key groove and the minimum aperture were obtained at several height difference between adjacent monoliths. The allowable height difference was determined on the condition of meeting the grouting requirements of transverse joints. The result shows that the allowable height difference for Xiluodu arch dam should not be more than 30m.

Study on Speed Measurement of Steam Turbine Shaft

Speed signal is an important monitoring signal in Steam Turbine Condition Monitoring And Fault Diagnosis(TDM) system. A review on the existing speed measurement methods of rotary machine was proposed to find out the defects of each method. A new approach was introduced to fulfill steam turbine speed accurate measuring. The periods of phase signal pulse generated by the key groove and speed signal pulse generated by the velocimetry gear, were measured respectively by the two independent 16-bit timer/counters, and the "counter overflow" problem was resolved by calling a byte memory unit. According to the record number of the counter, the value of steam turbine speed was calculated accurately. The method of steam turbine speed measurement proposed in this paper can not only simplify the structure of a TDM system, but also reduce its cost.

Reducing thickness variation of hot rolled steel strip by non-circular back-up roll geometry

Typically, back-up rolls in hot strip mills are equipped with sliding bearings and it is common to use a key that prevents relative motion between the conical sleeve and the roll shaft. The key groove causes deformation of the sleeve under load. This sleeve 'spring' is observed as rolling force variation, which causes systematic thickness variation of the steel strip. Although there is a keyless bearing construction on the market, an alternative solution was studied. A non-circular camlike geometry that compensates the sleeve spring was ground on the back-up rolls by a three-dimensional grinding method. As a result, ∼50% of the rolling force and the thickness variations, which were synchronised with the back-up rolls of the mill stand studied in the present paper, were reduced.

Three-dimensional thermo-elastic–plastic finite element modeling of quenching process of plain-carbon steel in couple with phase transformation

This study focuses on finite element investigations of quenching process which is commonly applied to improve mechanical properties such as strength, hardness, and wear/fatigue resistances, etc. During the quenching process, various kinds of microstructures evolve depending on the cooling rate and temperature variation within the steel. This microstructural evolution has a significant effect on the final dimension and geometry of the mechanical parts. In order to investigate the effect of temperature variation and phase transformation on the dimensional change and stress distribution, thermo-elastic–plastic constitutive equation coupled with the mechanical strain, thermal strain, phase transformation strain, and transformation induced plasticity is described in detail. Using the constitutive equation introduced, a finite element program was developed and used to predict distributions of the temperature, volume fraction of each phase transformed, and stress and dimensional change of the cylindrical specimen, shaft with key groove, and cam-lobe made of carbon steel. It was found out that numerically obtained values such as temperature history and stress distribution were in good agreement with the data available in the literature for the cylindrical carbon steel specimen. The developed program can be used for better understanding of mechanics involved with the quenching process.

Dynamics and generation of stress waves in cracked graphite moderator bricks

In the present study, static and dynamic analyses have been performed for graphite moderator bricks with and without key grooves under the different initial loading conditions of pure bending and slot rotation by using the finite element method. The possibilities of the occurrence of multiple cracking due to internal stresses have been investigated in terms of the (1) initial loading condition; (2) vibration mode shapes; and (3) damping of the bricks. Firstly, modal dynamic analysis has been carried out, and the effect of the initial loading conditions, such as pure bending and slot rotation, on the dynamic stress responses was investigated. It was found that stress enhancement was more significant under the condition of pure bending than that of slot rotation. For pure bending, the key groove which was opposite to the primary cracking site had the maximum dynamic circumferential stress. This implied that secondary cracking might occur at this position under pure bending. Secondly, in order to investigate the dominant mode shape for the stress enhancement, natural frequency analysis has been conducted. Fast Fourier Transformation (FFT) has also been performed to convert time–domain stress responses into frequency–domain stress responses. The initial loading conditions determined which mode shape was dominant for the stress enhancement. It was also suggested that a fundamental mode shape principally contributed to the occurrence of the multiple cracking. Thirdly, modal damping analysis has been performed, and the effect of damping on the stress enhancement was studied. It was found that damping had little effect on the initial peak of the dynamic stress response. This suggested that secondary cracking might still occur at the key groove opposite the primary cracking site, even if damping was present. The results of the analysis give a fundamental insight into the mechanism that may lead to multiple cracking in graphite components subject to internal stresses. However, the effects of 3-D, crack propagation speed and external restraint have not been taken into consideration in the present study. These effects may mitigate the possibility of secondary cracking, and are parts of further investigation.