Currently, rotary draw bending is frequently used method in industry. Nevertheless, it has been limited for long time by different types of defects. Submitted thesis deals with the study of the influence the bending radius and wall thickness on the quality of bent. Practical part of the thesis includes experimental rotary draw bending of tubes. The work also solves determining actual values of the wall thickness; ovality, bent shapes, the section modulus in bending and the neutral axis of the tube On the basis of evaluation of criteria are then set the parameters of permissible bend

Extensive research has been done over the years and has contributed quite a lot to the development of 3CR12 stainless steel. Nevertheless, there is still much to be understood about the behaviour of this steel during its production. One of the problems that are occasionally encountered is the side bulging effect i.e. the unconstrained narrow faces of the strand plastically bulge due to ferrostatic pressure from the liquid core of the strand at high temperatures. In general, this problem is prevalent in ferritic stainless steels as they exhibit a weaker hot strength than austenitic stainless steels. Coupled with side bulging, there is also strand width variation at high temperatures i.e. when the steel is in the ferrite-austenite dual phase region. Both of these dimensional changes to the slab profile create some processing problems in subsequent hot rolling operations when unacceptable width variations are encountered. This work was, therefore, motivated by the requirement to quantify the role that the metallurgical behaviour of this steel plays with regard to the above width variation problem. The research work involved studies of the <font face="symbol">d</font>-ferrite to austenite phase change during continuous cooling (simulating cooling during continuous casting) and the establishment of CCT diagrams, the influence of chemical composition on the austenite start temperature and the hot ductility and hot strength visà-vis the side bulging effect. The casting conditions in the mould are crucial to ensure that the solidification shell is thick enough to withstand the ferrostatic pressure exerted on the unconstrained narrow sides of the strand as it exits from the mould. Therefore, part of the solution lies in the study of the optimisation of the cooling rate, mould flux properties, casting speed, mould taper angle and the chemical composition of this steel, among other factors. Additions of austenite formers, within the specification range of 3CR12, should be favourable for a stronger solidification shell since austenite exhibits superior hot strength to <font face="symbol">d</font>-ferrite. The good hot ductility observed in 3CR12 may also provide a leeway for increasing the secondary cooling rate in order to form a thicker solidification shell soon after emerging from the mould. This may reduce the side bulging effect. This can be achieved without a risk of transverse cracking if the cooling is adjusted carefully. As long as the <font face="symbol">d</font>-ferrite to austenite phase ratio keeps fluctuating due to variations in (i) the chemical composition within the specification range and (ii) the cooling rate in the dual phase region from cast to cast, the strand width variation effect will persist. This is simply because of the effect these have on the ferrite to austenite phase ratios through the differences between the lattice structures of these two phases. Ferrite being less dense than austenite, occupies more volume than austenite, thereby affecting the slab width. The remedy to this problem is to control within stricter chemical composition limits in order to reduce or completely avert this width variation effect. / Dissertation (MSc (Metallurgy))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

Master thesis analyzes rotary draw bending of the tubes without using a mandrel. Bending process is accompanied by many defects due to large displacement of formed material. One of the major defects is flattering of the cross section also called ovality. In order to decrease ovality comes up a proposal of the changes to the tool design. Modifications of tool’s geometry are numerically analyzed by finite element method in software ANSYS. According to the results of the simulations an optimized pressure die is manufactured. Several experimental tests are accomplished to verify the effect of the optimized tool design. Approximately 100 bends confirm a decrease of ovality using modified pressure die.

This master’s thesis deals with design of a hydraulics bending machine. Bending machine will be used primarily for bending reinforcement bars in the shape of stapes. It consists of bending, sliding and chute system, which are located in the machine frame. Drive of each system is provided by a rotary and two linear hydraulic motors. Then there is described a hydraulic system and selection of its most important parts. Work is supplemented by visual documentation in the form of images of individual systems were processed in a CAD system Inventor 2010

This diploma thesis describes the creation of the technological process for shelf clutch production. The shelf clutch will be made of material 11 321 by cutting and bending technologies. The first part of thesis includes the theoretical description of cutting and bending technologies. The second part contains calculations and design proposal of final combined cutting and bending tool and also selection of pressing machine. The thesis contains the unit block layout of the combined cutting and bending tool and detailed drawings of cutting and bending parts of the tool. The shelf clutch drawing is included too.

Horseshoes are manufactured metal plates developed in an extensive assortment of materials and shapes and their main function is to protect the horse’s hooves and legs against abrasion and rupture. After a certain period of time the horseshoes are lost, worn out, or the hoof needs to be treated. Horseshoeing is a repetitive time consuming process for the farrier who has to heat the horseshoe inside a forge until it reaches the required temperature and shape it with a hammer until it fits perfectly to the horses’ hoof. The main goal of this project is to develop a horseshoe bending machine able to shape the horseshoe so its shape fits perfectly the horse’s hoof. The calculation of the bending force needed to be applied to the horseshoe in order to provoke a plastic deformation will be done with Euler-Bernoulli beam theory. The bending force is then used to design and dimension each element of the bending mechanism so that it may be able to resist the stresses and prevent the parts from collapsing during its working life span. A study of the springback effect will be done followed by the analysis of the hertzian contact stresses between the rollers and the horseshoe. In addition, a clamping system is selected to constrain the movements of the horseshoe during the bending process. This machine will reduce the final user’s horse maintenance costs at the same time that makes the fitting process easier and less demanding, which will improve the farrier’s working life span and quality.

Laminated glass (LG) consists of two or more glass layers bonded by an elasto-polymeric layer, the most commonly used being PVB (Polyvinyl Butyral). LG has improved safety properties compared with single layer glass because the interlayer prevents large sharp pieces from spreading when the glass is broken by impact. Even if one of the layers breaks, the other layer(s) still contribute in carrying the load. Through proper understanding of the interaction between the interlayer and the glass LG could be used in engineering as a load bearing material to a larger extent. This study aims at gaining a deeper knowledge of the behaviour of laminated glass by experimental investigations and by numerical model simulation. To pursue the proposed study, three point bending test with simple support conditions were performed for single layer glass and laminated glass units with three different types of interlayer materials. Corresponding finite element numerical models were created in the software ABAQUS to fit the model with experiment to obtain the bending stiffness and shear stiffness of the interlayer material. The PVB tested showed viscos-elastic material properties, whereas other two interlayer materials, Solutia DG 41 and Sentry Glass, showed linear elastic properties. PVB is the least stiff interlayer material among the three types. Solutia DG 41 and Sentry Glass have similar stiffness, about 13 to 15 times stiffer than the PVB. The behaviour of laminated glass lies in general between the two limits of a layered glass unit with no interaction and a monolithic unit of the same total thickness, depending on the stiffness of the interlayer material. Failure tests of the specimens were also carried out. The obtained strength of glass from four specimens is 80 MPa to 92 MPa with a variation of about 15%. The number of more performed experiments would have better outcome for strength of glass. The bending stiffness of the laminated glass as estimated with the numerical model fitted well with the experimental results with an error of about 2%. Hence the experimentally and numerically obtained results show a good correlation and are thought be possible to use in future larger scale modelling.

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Bending of thin-walled tubing to a prescribed bend radius is typically performed by bending it around a mandrel of the desired bend radius, corrected for spring back. By eliminating the mandrel, costly setup time would be reduced, permitting multiple change of radius during a production run, and even intermixing different products on the same line. The principal challenge is to avoid buckling, as the mandrel and shoe are generally shaped to enclose the tube while bending. Without the shaped mandrel, buckling will likely occur sooner, that is, at larger bend radii. A test apparatus has been built for arborless bending. It has been used to determine the limits of bend radius, wall thickness, material properties, etc. on buckling. Key to the process is a set of moveable clamps, which grip the tube and rotate to produce the bend. A complex control system moves the clamps radially to maintain pure bending, without superimposing tension or compression. A series of tests were performed to document the safe region of operation to avoid buckling. Charts have been created to assist the operator, as well as the design engineer, in determining the minimum bend radius. Similar tests will be required for each additional tube size, thickness, material, etc.

No / This paper presents a series of test results of elliptical concrete filled steel tubular (CFST) beams and columns to explore their performance under bending and compression. A total of twenty-six specimens were tested, including eight beams under pure bending and eighteen columns under the combination of bending and compression. The main parameters were the shear span to depth ratio for beams, the slenderness ratio and the load eccentricity for columns. The test results showed that the CFST beams and columns with elliptical sections behaved in ductile manners and were similar to the CFST members with circular sections. Finally, simplified models for predicting the bending strength, the initial and serviceability-level section bending stiffness of the elliptical CFST beams, as well as the axial and eccentric compressive strength of the composite columns were discussed.