Dynamic analysis of two types of over-crank guillotine shears—a comparative study

Guillotine side trimming shear machine: A case study of plate mill in Bhilai steel plant

Abstract: Article history: Received 6 October, 2015 Accepted 23 April 2016 Available online 24 April 2016 Double-sided trimming shear machine is used for longitudinal both–sided trimming of steel plates and simultaneous scraping of trimmed edges at specific length. Side trimming shear (STS) executes the most vital role in increasing the productivity of plate mill and due to its feature, efficiency of plate mill division is enormously increases. In general, frequency of the occurrence of breakdown in STS machine is a most challenging task when STS performs side trimming and scrap cutting machining process. Bhilai Steel Plant (Steel Authority of India at Bhilai) in India is continuously facing a problem due to breakdown of STS machine. The use of separate knife for side trimming and scrap cutting reduces the possibility of scrap jamming which is a major reason for breakdown of STS machine. Researchers and practitioners also suggest the use of arc guillotine shear for side trimming and straight guillotine shear for scrap cutting for minimizing the breakdown in STS machine. The aim of this study is to describe the problems faced by the steel industry as well as the necessary steps which should be taken for improvement of the productivity of STS machine and also it has made contribution to Bhilai Steel Plant by its growth and prosperity. The methodology of study is purely qualitative and the results point out the problems, its implications, steps taken to improve the overall productivity of Bhilai steel plant. © 2016 Growing Science Ltd. All rights reserved.

Numerical Analysis of the Deformation of a Shearing Machine Tool under Excessive Blade Clearance

Abstract: Guillotine shearing machines for metal sheet may be inadvertently operated at increased blade clearance. Typical cases were studied using commercially available finite element software with an explicit solver. Loads causing elastic deformation to the machine structure arise from plastic deformation of the sheet metal being processed, its behavior being modelled by modified Johnson-Cook law. Excessive clearance was found to overload the machine considerably compared to normal clearance, owing to considerable lateral forces. As a result, the guillotine and much less so the base of the machine, undergo oscillatory deformation and the sheet is partly sheared and mostly bent. Such analysis helps the designer understand structural issues of the machine tool in extreme situations and modify the design appropriately.

The finite element method in engineering science

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On the role of Rayleigh damping

Abstract: The computation of the Rayleigh damping coefficients α and β is an important consideration in the area of the modal superposition technique. In this paper, an experimental investigation carried out on square and rectangular plates with various boundary conditions to determine the damping ratios for a few modes of vibration is reported. Based on the experimental findings, the Rayleigh damping coefficients can be computed for subsequent use in the modal superposition technique.

Design aspects and parametric study of 3-roll heavy-duty plate-bending machines

Abstract: The fabricated stands of a three-roll heavy duty plate bending machine under load have been studied and a parametric study has been performed on them. The two machines analyzed are capable of cold rolling 14 and 40 mm thick plates. The FEM was used to study the static response of the stands when the machine is in operation, and three-noded triangular plate elements were used for this purpose. The response was computed for the worst case of loading. Cholesky's method in conjunction with the skyline approach was used to study the behaviour of the stand by solving the large-size problem. The objective of the parametric study was to evaluate the performance of the machine stands in relation to various design- or structural-modification and arrive at a satisfactory design.

Design aspects and detailed study of medium tonnage mechanical press brakes

Abstract: The fabricated stands, bed and ram of a medium tonnage mechanical press brake under load are studied. The machine analyzed is capable of handling a variety of bending operations on sheets of up to 6.5 mm thickness. FEM is used to study the static response of the stands when the machine is in operation, three-noded triangular plate elements being used for this purpose. The response is computed for the worst case of loading. Cholesky's method in conjunction with the constant bandwidth approach is used to study the behavior of the stand, the solution of which results in the computing of a large number of unknowns. The objective of the study is to evaluate the performance of the machine stands, the bed and the ram, when the machine is subjected to various loading conditions. Isostress lines are plotted to enable the stress pattern to be studied, based on which study various design and structural modifications to arrive at a satisfactory design have been suggested.

Dynamic analysis of a guillotine shearing machine

Abstract: The major components of guillotine shears, both over-crank and under-crank, including the side-stands, the bottom connecting plate, the hold-down, the top connecting plate and the blade carrier, are examined critically for rigidity and strength, vibration characteristics, dynamic stresses and factor of safety whilst the shear is in operation. The vibration and strength characteristics of the machines and the blade carrier, when the thickness of the plates are changed, are also examined.