Investigation of the Accuracy of the Height Dimensions of Forgings for Cold Volumetric Stamping Processes by the Computational and Analytical Method
Issue:
Volume 12, Issue 2, March 2023
Pages:
20-25
Received:
10 February 2023
Accepted:
1 April 2023
Published:
13 April 2023
Abstract: In mechanical engineering, product quality indicators are inextricably linked with the accuracy of machining parts. The dimensions, shape and location of the surfaces obtained during processing determine the actual gaps and tightnesses in the joints of machine parts, and consequently, the technical parameters that affect the quality, reliability and economic performance of production and operation. Very often in practice, the achievable accuracy of processing, including cold volumetric stamping (HOS), is judged by the accuracy tables contained in special reference literature. Such tables contain indicative data on achievable accuracy for various technological operations, obtained by systematization of direct long-term observations in production conditions. However, the peculiarities of individual operations do not allow us to give a conclusion about the accuracy of stamping by analogy with other operations, since there is no comprehensive similarity between them. In particular, the sizes and shape of the initial blanks differ, mechanical the properties of their material, the friction conditions in the die cavity, the characteristics of the press used and other technological factors. Thus, taking into account the listed circumstances, in each specific case it is necessary to calculate the accuracy of processing, which should have the ultimate goal not only to obtain a numerical result, but first of all to disclose the mechanisms of accuracy control. The calculation of the processing accuracy should be carried out taking into account the methods of obtaining dimensions and methods of setting up the technological system. The article is devoted to the computational and analytical method for calculating the forging accuracy based on the application of the theory of parametric sensitivity.
Abstract: In mechanical engineering, product quality indicators are inextricably linked with the accuracy of machining parts. The dimensions, shape and location of the surfaces obtained during processing determine the actual gaps and tightnesses in the joints of machine parts, and consequently, the technical parameters that affect the quality, reliability an...
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Cytotoxic Effects of Simvastatin on Normal Human Osteoblasts
Kanwal Maheshwari,
Laisheng Chou
Issue:
Volume 12, Issue 2, March 2023
Pages:
26-35
Received:
8 June 2023
Accepted:
10 July 2023
Published:
21 July 2023
Abstract: Statins, hydroxymethylglutaryl-coenzyme-A reductase inhibitors (HMG-Co-A), are known to reduce plasma cholesterol levels. However, the biocompatibility of Simvastatin with human bone tissue has not been studied thoroughly. The purpose of this study was to further investigate the effectiveness of different concentrations of simvastatin on the attachment, proliferation, toxicity, cell cycle, and apoptosis of normal human osteoblasts. Osteoblasts derived from normal human alveolar bone chips were cultured with simvastatin at concentrations of 1, 10, 25, 50, 75, 100 mol/L, and 0 mol/L as a control. The cell attachment was evaluated at 9 hours. The proliferation rate and cytotoxicity were investigated at 7, 14, and 21 days. Cell cycle and apoptosis were assessed at 1 and 3 days. Statistical analysis was performed using ANOVA. P-values ≤0.05 were considered statistically significant. The results showed that there was no statistical significance (P>0.05) amongst the groups in the cell attachment efficiency. All tested concentrations of Simvastatin showed a significant decrease in the proliferation rate (P<0.001) and an increase in cytotoxicity (P<0.001). Cell cycle and apoptosis significantly increased as time increased (P<0.001). In conclusion, the present findings showed that Simvastatin adversely affects human osteoblasts' proliferation and cell viability by inducing apoptosis.
Abstract: Statins, hydroxymethylglutaryl-coenzyme-A reductase inhibitors (HMG-Co-A), are known to reduce plasma cholesterol levels. However, the biocompatibility of Simvastatin with human bone tissue has not been studied thoroughly. The purpose of this study was to further investigate the effectiveness of different concentrations of simvastatin on the attach...
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