Bend radius

About: Bend radius is a research topic. Over the lifetime, 3303 publications have been published within this topic receiving 35415 citations. The topic is also known as: minimum bend radius.

Towards an integrated robust and loop tooling design for tube bending

Abstract: Bent tubular parts have attracted extensive applications in various industries due to high strength and light weight. However, tube bending (TB) is a strong knowledge-based tri-nonlinear physical process with multi-tool constrains, and minor inappropriate tooling design may induce several failures such as wrinkling, over thinning (even fracture), section distortion, and springback. In response to the urgent requirements of the tubular products with mass quantities and diverse specifications, we proposed an integrated methodology for robust and loop tooling design for TB by combining several technologies such as knowledge-based engineering, parametric CAD modeling, and parametric finite element modeling. Via the spreadsheet formatted rules extracted from different sources of knowledge, several sequences are automatically conducted to preliminarily avoid the wrinkling and section distortion, including the selection of tooling sets (bend die, clamp die, pressure die, wiper die, or mandrel die with flexible balls), the determination of die dimensions, 3D modeling of both external and internal tools, die assemble, and the selection of material type for each die. Then, by importing the feature parameters of tools into 3D-finite elements models, the bendability of tube under previously designed multi-tool constraints is quantitatively evaluated in terms of multi-defect, and the springback can be calculated to redesign the bending die by radius reduction. The design variables are only tube diameter, wall thickness, bending radius, bending angle, and material types. The tool design system is then implemented, and the reliability and efficiency of the system are experimentally verified in the aviation industries regarding several practical bending cases with different specifications and tubular materials.

Accurate and efficient fiber optical shape sensor for MRI compatible minimally invasive instruments

Abstract: Background: The mechanical properties of small minimally invasive instruments are limited and thus must be treated as flexible instruments. Proper functional behavior of these instruments can be significantly enhanced when the instrument is equipped with a shape sensor to track the path of the flexible instrument. MRI compatible instruments, and thus the corresponding paths, are long in particular. Therefore, the accuracy of the tip position is stringent. Approach: We have developed and realized a thin Fiber Bragg Grating (FBG) based fiber optical shape sensor. The main advantages of this fiber optical sensor are its minimum dimensions, the intrinsic MRI compatibility, and the ability of sensing deformation with submicro-strain accuracy. The shape sensor consists of three fibers, each equipped with multiple FBG's, which are integrated physically by gluing and can be positioned inside an flexible instrument. In this study a critical component analysis and numerical error analysis were performed. To improve performance, a calibration procedure was developed for the shape sensor. Results and Conclusion: With current state of the art interrogators it is possible to measure a local deformation with a triplet of FBG sensor very accurately. At high radii of curvature, the accuracy is dominated by the interrogator, whereas at low radii of curvature, the position of the fibers is leading. The results show that position error of a single segment of the shape sensor (outer diameter of 220 μm, a segment length of 23.5 mm and a minimum bending radius of 30 mm) could be measured with accuracies (3σ) of 100 μm for low radius of curvature upto 8 μm for high radii of curvature. © 2012 SPIE.

Effect of macro-bending on dispersion of dispersion compensating fibres

Abstract: Using direct measurement, the effect of macro-bending on the dispersion in dispersion compensating fibres was investigated It was shown that even a relatively large bend radius of /spl sim/10 cm can modify the fibre dispersion in the range 1500-1600 nm

Effect of Mechanical Loading on Coated Conductor Tapes Due to Winding Onto Round Cables

Abstract: The influences of stresses/strains on critical current, I c in REBCO high-temperature superconducting (HTS) tapes wound onto a round cable were investigated. In the first step, the HTS tapes were helically wound on copper tubes with various diameters in the range of 2.95-8 mm. Considerably better results were achieved in case the superconducting layer was positioned during the winding at the inner side of the helix. The cables with tape wound on the tube with a diameter of 6.35 mm were subjected to bending tests with various bending radii in range from 21 to 60.5 mm. The I c degradation as a function of both the tube diameter and bending radius has been assessed from a current- voltage curve, from which the critical current was determined. The I, degradation in all samples was confirmed by microstructural investigation of an HTS layer by scanning electron microscopy.

Manufacture of elbow by bending pipe possessing irregular wall thickness

Abstract: PURPOSE:To contrive to reduce the working cost required at the place where the use of the elbow is inevitable, by applying the high frequency induction heating and bending, which are both freely adaptable to any bending radius, to the pipe possessing irregular wall thickness or to the round steel bar, in manufacturing the pipe with uniform wall thickness. CONSTITUTION:The inner surface of the pipe possessing the wall thickness to be specified by T=(designed minimum wall thickness) divided by (1- thickness reducting rate) (the round steel bar is also available) is mechanically machined to form the irregular wall thickness, and thus obtained thin wall thickness is specified as (the designed minimum wall thickness) divided by (1+ thickness increasing rate). This pipe 1-1 of irregular wall thickness is fixed by the guide support clamp 2 and the middle point clamping jig 3 so as to place the thick wall T on the outside and to place the thin wall C on the inside in respect of the bending neutral axis; and the tip of the pipe 1-1 is clamped by the arm point 6 being set at the specified radius R centering at the bending point 4. At the middle of the pipe 1-1, the guide roller 7 and the flattening preventive guide 8 are installed; then while the pipe 1-1 is being heated to the specified temperature by the work coil 11, the pipe 1-1 is pushed and bent by the hydraulic cylinder 10, the pipe feeder 9 and the jig 3; following to this, the bend zone Z is directly cooled. After, that the pipe 1-1 is cut at the planes X-X and Y-Y, and the elbow is obtained.