Showing papers on "Bend radius published in 1991"

Preterminated fiber optic cable

Abstract: A predetermined optical fiber cable has a main trunk cable comprising a plurality of optical fibers disposed therein and multiple drop cables spliced to the trunk cable at various branch points, the preterminated fiber optic cable being completely assembled at the time of manufacture and is easily installed thereafter. At each branch point an optical fiber cable splice closure is utilized for protecting the optical fibers and splices from moisture and mechanical damage, providing a strong anchoring point for the optical fiber drop cable, and insuring that the minimum fiber bend radius is not violated. The splice closure is cylindrical in shape and has a cavity providing room for the splices and for excess optical fiber storage. Because the splice closure is relatively small (an outer diameter of no greater than 4 inches and a length of no greater than 7 inches), the preterminated fiber optic cable, after manufacture, may be wound in reels for installment without incurring cable or fiber damage and, further, may be depolyed within standard PVC piping having a 4 inch inner diameter. The preterminated fiber optic cable may also be preconnectorized.

Bend loss in large core multimode optical fiber beam delivery systems.

Abstract: We present results of an experimental investigation of the optical losses produced by bending large core optical fibers, typical of those used in power beam delivery systems. Experiments have been conducted over a range of core diameters for both plastic clad silica and all-silica fibers as a function of bend radius. A theoretical model has been developed for predicting the magnitude of the bend loss, and agreement was obtained with the experimental results. The study thus yields design information for fiber beam delivery systems.

Splice tray and method

Abstract: A splice organizing tray can protect the optical fibers from excessive stress if the fibers stored in the tray are organized in paths which do not require bending of the fibers beyond their approved bend radius, which do not require the fibers to cross, and which maintain the fibers in contact with the support substantially all the time. The tray has a convex bottom wall to urge the fibers against the edges of the tray, a recessed splice support area, and resilient snaps to engage the ends of the splices to permit the splices to be placed closer together. Holes below the splices afford the removal of the splices without danger to the adjacent fibers.

Miniature fiberoptic bend device and method

Abstract: Bends in optical fibers (14) can be miniaturized by reducing the diameter of a section (18) of the fiber in the region where bending (20) is desired. In one aspect of the invention radii of curvature less than 100 microns and very low optical power loss are achieved. A fiber with greatly reduced diameter (Fig. 1d, Section-b-b) may also be twisted about its longi-tudinal axis to a greater degree than a comparable length of larger diameter fiber. In another aspect of the invention, reduc-ing the cross-sectional area of fiber is not required. Bent sections of the fiber are thermally annealed forming stress free bends of minimum bend radius for long term applications. Any optical fiber can be processed by redrawing and/or chemical means to allow such bending or twisting. Bend or twist tolerant regions and annealed bends may be packaged separately or built integrally into a wide range of fiber optic components; sensors; networks, or systems with significant space savings, added performance features and mechanical flexibility.

Filter device with micropleats and macropleats

Abstract: A high efficiency air filter is described which comprises a depth filter sheet that has been formed with micropleats stabilized by application of a strip of a thermoplastic adhesive across the peaks of the micropleats and then formed into a macropleated structure with the axes of the micropleats and the macropleats being essentially parallel. The micropleats preferably have a bending radius of less than about 0.01 inch.

Bending detection device

Abstract: PURPOSE:To enable a bending radius of a detector of an amount of bending to be suppressed to a proper value and a durability to be retained. CONSTITUTION:A detector 1 of a mount of bending which consists of a resistor with a flexibility which outputs a signal corresponding to bending and a flexible member 9 which controls a minimum bending radius of the detector 1 of an amount of bending to a value which is equal to or more than a limit bending radius are provided.

Method and apparatus for manufacturing a stabilizer bar

Abstract: A stabilizer bar or a similar metallic tube product for vehicles, has a central portion and at least two bent portions forming legs. The bar includes a thick-walled metallic tube having in the central portion a wall thickness and outside diameter in a ratio amounting to at least 1/10. This tube has an outside wall portion bent with a restricted thinning, ranging from about 5 to 15%. The bent portions are bent with an average bending radius of curvature in the range from about 1.4 to 2.1 times the outside diameter of the tube. Apparatus and methods can manufacture stabilizer bars or similar tubular metallic products of the foregoing type. For example, a method includes the steps of fitting to a bending arm one end of the thick-walled metallic tube. An inside wall portion of the tube has a radial spacing from a bending center of curvature, no greater than the length of the bending arm. The tube and the heating zone move relatively, with the heating zone advancing along the tube. Circular movement of the bending arm is resisted with a force sufficient to displace the flexure plane (separating compression zone from tension zone) radially outward from the center of curvature and to thin the outside wall of the metallic tube by about 5 to 15%. Resistance of the circular movement can be preformed with a gear and gear rack.

Secondary cells and separation in developing laminar curved-pipe flows

Abstract: Laminar flows through 180° curved bends of circular cross section are investigated numerically. For small curvature ratio, α, defined as pipe radius over mean bend radius, the governing equations could be parabolized. The equations are solved for an α range of from 0.04 to 0.143, a Dean number (De) range of from 277.5 to 1360, and for a uniform flow, a potential vortex, and a parabolic flow inlet condition. In all these studies a zero cross-stream flow at the inlet is assumed. A detailed study of the effects of α, De, and inlet condition on the secondary flow pattern is carried out. Within the range of parameters investigated, up to three secondary cells are found in the cross-stream half-plane of a curved pipe. They are the Dean-type secondary cell, a secondary separation cell near the inner bend (closest to the center of curvature of the bend), and a third cell near the pipe center. The number of secondary cells in the cross-stream half-plane is greatly influenced by the inlet flow, and to a much lesser extent by α and De. For example, only the Dean cell is found in a curved-pipe flow where α and De are small and the inlet flow is either uniform or a potential vortex. When the inlet condition of the same case is changed to a parabolic flow, a three-cell structure results. Furthermore, as De increases to 1180, incipient axial flow separation begins at around 23° downstream of the curved-pipe entrance. The formation and extent of the separation and third cells are investigated together with their dependence on the parameters studied. This investigation further shows that, within the range of parameters examined, there is no secondary cell occurring near the outer bend, contrary to some earlier findings on fully developed curved-pipe flows.

Heat reshapeable regid conduit

Abstract: A heat reshapeable rigid conduit and method for forming an elbow or offset having any desired bend radius therefrom. The rigid conduit is formed of a flexible metal tubing with a layer of heat softenable plastic preferably covering the exterior surface thereof. The conduit may be heated using conventional electric heaters on the job site, then shaped into the desired bend radius to form an elbow or offset. The plastic layer provides rigidity to the elbow or offset upon cooling. The flexible metal tubing has interlocking overlapping joined edges that permit flexing of the tubing when the plastic layer is heat softened. The flexible metal tubing resists the sawing action of a pulling line during the installation of an electrical conductor in the conduit. The plastic outer layer permits quick and inexpensive coupling between adjacent conduit sections. The heat reshapeable rigid conduit may be formed by extruding a plastic coating on the exterior of the flexible tubing, or may be formed by frictionally fitting a length of flexible metal tubing inside a length of plastic tubing. A section of the rigid conduit may also be heated and extended to correct for any error in measurement or cutting.

Bent slab ray theory for power distribution in core and cladding of bent multimode optical fibres

Abstract: The power in the core of a bent multimode slab is calculated on the basis of ray theory as a function of the angle round the bend, and as a function of the bend radius of curvature. The effect of cladding thickness is also taken into account. Measurement of the power in the core of a bent multimode fibre supports the validity of the two dimensional slab model used, and also the mechanism of refracting rays being responsible for the power transfer to and from the core of such bent fibres.

Effect of bending on zero dispersion operation of single-mode optical fibers.

Abstract: Perturbation theory for bent optical fibers predicts that the unperturbed (straight) propagation constant (or effective index) will be corrected by a small term that is proportional to (R(b))(-2), where R(b) is the radius of the bend. We examine how this small correction affects the chromatic dispersion of the fundamental mode, and in particular we examine the changes that occur when the fiber operates at the zero dispersion wavelength lambda(o). For a bend radius of 1 cm, lambda(o) may shift by up to 20 nm.

Bend reducing feed in for filament payout tubes

Abstract: An improvement is disclosed for payout tubes secured within a container for a coil of cable therein so that the tube projects at its exit end through a hole in a wall of the container. The tube is adapted to dispense cable fed into its entrance end from inside to outside the container. The improvement is, broadly, providing at such entrance end a curved cable support surface extending around the tube of large enough radius of curvature to prevent deformation in cable, fed in contact with the surface into the tube, of tight bends causing kinking of and damage to the cable. Such surface may be provided either on a cap in turn fittable onto the tube at its entrance end or, alternatively, directly on the tube at that end.

Polymer based articles having increased structural rigidity

Abstract: The present invention relates to a product for structurally supporting polymer chains comprising fullerene molecules mixed with a polymer mass wherein the fullerene molecules have a relatively large bend radius over which the polymer chains contained therein can be deformably flexed.

Method and mould assembly for bending complex shapes on a glass sheet

Abstract: The invention relates to a method and a mould assembly for bending complex shapes on a glass sheet. The invention relates also to a bending mould and its manufacturing method. A heated glass sheet placed upon a ring mould (5) is bent to its final shape by means of an overhead non-contacting mould (6) whose curved lower surface (7, 8) is provided with blasting orifices (10) and suction orifices (11). Blasting orifices (10) are used to blow hot air for heating a glass sheet at least locally while building an air cushion between shaping surface and glass sheet. The hot air blown from blasting orifices (10) is used to apply a greater heat volume to those sections of the glass sheet surface in which the bending radius of a glass sheet is the smallest or deformation (elongation, bending) is the greatest.

An Erosion Resistant Pipe Bend

Abstract: An new 90-deg bend shape has been developed for erosion resistance. The design consists of a gradually expanding inlet, a large-diameter curved section, and a gradually contracting outlet. Tests were conducted using alumina particles in air at an average velocity of 27 m/s, passing through a carbon steel bend. The new bend design had an erosion life exceeding 4000 hr, compared to 38 hr for a conventional bend design

Limiting device for bending and deformation of cable

Abstract: PURPOSE:To limit bending deformation surely by providing a bend limiting member having an arched guide surface the radius of which is less than the initial bend radius before the inside arc surface is deformed and greater than the allowable bend radius of a cable. CONSTITUTION:A bend limiting member 6 is made concave so as to be in line with the circumference of a cable on both sides of its cross section. In the longitudinal direction the bend limiting member 6 is bent with a designated radius R so that the concave surface may be expanded outward, by which an arched guide surface 6a is formed. The guide surface 6a is supported so as to stretch in a row to a cable gripping groove 3a of one of clamp main bodies 3 by fixing an end of it in the longitudinal direction by welding, etc., to the periphery of the cable gripping groove 3a. This radius R is selected within the limits less than the bend surface when the offset-shaped cable was designed and within those over no minimum value of the allowable bend radius of the cable.

Predicted curvature of a glass fiber from the measured curvature of its coating

Abstract: An analytical stress model is developed to evaluate the elastic curve of a glass fiber whose coating has a constant (measured or imposed) bend radius. It is shown that in order to predict the bending behavior of a coated glass fiber subjected to bending a parameter u should be computed which depends, in addition to Young's modulus and diameter of the glass fiber itself, also on the length of the curved area and Young's modulus and outer diameter of the (primary) coating. In the range 0 >

Optical delay circuit

Abstract: PURPOSE:To obtain a large delay without increasing the shape by forming the circuit to the shape to turn back the bent part on an input side and the bent part on an output side along the circumference with which the bent parts come into contact in the form of a huge comma with each other on the same plane. CONSTITUTION:This circuit is formed of the input side optical waveguide 2a which heads for the center spirally from a light input terminal 1 at the bending radius larger than a permissible bending radius (r) and the output side optical waveguide 2b which is formed to turn back in the form of the huge comma along the circumference with which the two circles of the permissible bending radius come into contact with each other in the central part of the spiral then to head for a light output terminal 3 without intersecting with the input side optical waveguide 2a. The spiral optical waveguide patterns to turn back in the form of the huge comma along the circumference of the two circles, the radii of which are the bending radius (r) or above and which are in contact with each other, are used in such a manner and, therefore, the large delay time is obtd. with the small area.

Tracking studies of the Oxford Instruments compact electron synchrotron

Abstract: Simulating electron trajectories (tracking) in a realistic compact ring introduces special problems because the magnetic bending radius can be as little as twenty times the horizontal displacement. Common simplifying approximations in tracking codes may not be appropriate. Results are presented from a thin lens tracking code which correctly handles the small bending radius virtual forces and real magnetic forces to octupole level. Nonsymplectic behavior is controlled by highly segmenting the Oxford superconducting dipoles. A qualitative comparison with experimental results is made. >

Zero tolerance device

Abstract: Flexible remote controls of the type using ball bearings along their length are improved by externally imparting reversing bends along their length which bends are imparted by two semi-circular sleeves, having mirror image mating faces containing an interior contour of reversing radii, having arcs being the minimum bend radius of the partial flexible ball bearing remote control to which it is applied, which come tangent at the center and run out an equal depth from the centerline and repeat throughout the length of the flexible ball bearing remote control.

Bending method for metallic pipe

Abstract: PURPOSE:To allow to make the bending radius of the metallic pipe smaller by executing bending while holding the temperature of the outer side of the bending higher than that of the inside of the bending. CONSTITUTION:The metallic pipe material 10 is bent by utilizing the bending die 12, the pressing die 26, the clamping die 22 and, etc. Then the bending is executed while holding the temperature of the outside 36 of the bending higher than that of the inside 38 by utilizing the heater 42. Therefore, the outside of the bending applied with the tension is difficult to break because it is easily elongated, and the generation of wrinkles with buckling on the inside of the bending can be made more little because it has a large strength.

Relationship Between Scour Depth and Bend Radius of Curvature on the Red River

Abstract: Studies of bank and bend processes were undertaken on the Red River between Index, Arkansas and Shreveport, Louisiana in connection with the navigation project on the river downstream of Shreveport The aim was to establish the relationship between bend geometry and scour depth for bends with a variety of outer bank types The results show that the banks are formed in materials of five different origins: meander belt alluvium and clay plug materials associated with the present flood plain; back swamp deposits in a terrace left from the nineteenth century flood plain; Pleistocene/Tertiary materials in the valley walls; and revetments formed from riprap On the basis of an engineering-geomorphic analysis, a relationship between outer bank type and bend scour depth was found Generally, scour depth increases as outer bank resistance to erosion and failure increases, especially for tight bends of low radius of curvature to width ratio Maximum scour pool depths for revetted bends are 5 to 20% greater than those for the equivalent free, alluvial meander These results suggest that additional bed scour should be expected in a bendway as a consequence of stabilizing the outer bank, even if the original alignment is maintained The summary curves presented could be useful in predicting the degree of further scour which must be allowed for in the revetment design

Method for the hot bending of plastics in sheet form

Abstract: The invention relates to a method making it possible to bend, hot, completely safely and automatically, plastics in sheet form in order to obtain profiles of complicated shapes with an internal bending radius which can vary from zero to the thickness. It consists of a table (1), a stop (12) and a corner stop (8) which can be adjusted. The material is gripped against the stop (12) by means of the gripper (9). The operator, after having freed the table (board) (3) may then apply voltage to the electric resistor (resistance-heating element) (5). This will heat the material, the springs (7) will then entrain the table (3) and enable the material to be bent. At the end of bending, the power supply to the electrical resistor (5) will be cut off automatically. The method according to the invention is particularly intended for the manufacture of thin plastic casings.

Phase space calculation of bend loss in rectangular light pipes

Abstract: Angular momentum conservation and phase space are used for an exact calculation of bend loss in rectangular light pipes without rayiracing. It is found that the loss fraction ofrays in the bend plane is greater than that of the full 3-D distribution for any bend radius. There is excellent agreement between the calculated and measured loss.

Beam transport to the SXLS ring

Abstract: Design of a transport line with highly restrictive space and beam size requirements with the flexibility in the orientation of the injector is presented. An analytic method based on symbolic algebra is used to find optimal regions of the design parameters. The fine tuning of the parameters is performed with a standard matrix program. Special interest is paid to the question of dispersion vector matching the large angle bend with a very small bending radius using noniron bending magnets with very small gap areas. >

Working method for bending pipe

Abstract: PURPOSE:To execute bending of small bending radius of curvature by causing fluid for heating or cooling to flow into the tubular material to be bent and executing bending while heating or cooling the tube. CONSTITUTION:The tubular material (PIPE) 1 is guided with the supporting rolls 4a-4e. The tubular material 1 is tightened to the bending die 2 with the tightening die 3, the revolving force 8 is applied and it is worked with bending. Then the fluid 5 for heating or cooling are caused to flow into the material to be worked with bending from 6 and caused to flow out from 7. While heating or cooling the pipe 1, bending is executed. In such a way, the buckling to be easily generated in the bending inside is prevented.

Raney catalyst composition and vessel for containing same

Abstract: The invention relates to a Raney catalyst composition which comprises ice as a solid carrier. Portions of a Raney catalyst containing ice as solid carrier are added stepwise to the reaction mixture. The vessel 1 used for the storage and/or handling of the Raney catalyst has a conic casing or side walls 2 joining to the bottom 4 through a bend radius 3 of greater than 0.5 mm size. The vessel 1 is covered by a tightly closing cap 5.

Loop forming tool for cables and method of use thereof

Abstract: A tool for use in forming expansion loops in electrical communication cables or similar materials is formed of an elongated channel with opposing bends, thus forming a sinusoidal curve. The channel is twisted in order that the outer radius of each of the bends is contained within the walls of the channel. The tool is used by placing a length of electrical cable within one end of the channel and holding the electrical cable and any supporting line within the channel. The electrical cable is then grasped and held within the opposite end of the tool channel, and the tool is manipulated to form a sinusoidal curve in the electrical cable. The tool is then displaced along the electrical cable and simultaneously rotated 180 degrees, resulting in a mirror image of the first position. By again bending the electrical cable within the channel of the tool, a curve opposite the first curve is formed in the electrical wire, thus completing the formation of an expansion loop of consistent size and bend radius.

Manufacture of heat insulating door

Abstract: PURPOSE:To avoid the generation of eddy current as well as the entrapping of air in a foamed heat insulating material by a method wherein the bending curvature of a first corner between a flat surface and respective side surfaces and the same of a second corner between the respective side surfaces and an inward flange are made larger than the minimum radius of curvature while the curvature of the first corner is made larger than the curvature of the second corner CONSTITUTION:Growing speed of a foamed heat insulating material 6, poured into the flat surface 3A of an outer panel 3, will never be deteriorated compared with the minimum bending radius since the rounded surface of the first corner C1 glides the foamed heat insulating material 6 upward smoothly when it passes the first corner C1 in the condition of cream or gel, whose growing speed is high On the other hand, the foamed heat insulating material 6 is guided smoothly by the rounded surface of a second corner C2 when it passes the second corner C2 whereby the growing speed will never be deteriorated even in the state of foams According to this method, the generation of eddy current and air-entrapping in the foamed heat insulating material 6 can be avoided