# Method for making circular 90 degree long radius elbow

by yane Yang Sales Manager
Round elbow is round bend, is used to change the direction of the ventilation pipe fittings.
Circular 90 ° long radius elbow central Angle according to need, with double bevel pipe joint and a number of the two socket set with a single bevel.
The diameter of the bend to D, R bend radius of curvature, called the union with double oblique mouth "in section", the ends respectively located in bend a socket with a single bevel, called "nodes". As cylinder cross section is a circular, the inclined section is an oval, the circumference is different, can't bite, so the circular 90 ° long radius elbow must at both ends
Each set two nodes, so that is connected to a duct.
Bend caused by the size of the local resistance, mainly depends on the turning Angle of smoothness. 90 ° long radius elbow smoothness and depends on the size of the bending radius and the number of bend section, bending radius is big, the middle section number, resistance is small, but to take up space, but also more work; Small bending radius, the middle section number less, work less, but big resistance. For the three section, and the sockets of the two nodes. Circular 90 ° long radius elbow. Current rules, general ventilation and air conditioning systems of circular 90 ° long radius elbow bend radius and minimum number of section are shown in table
Circular 90 ° long radius elbow method is, according to the known bend diameter, Angle, and determine the bend radius and the number of section, to draw the visual figure, such as the diameter of 320 mm, the Angle is 90 °, the 3 section, two nodes, the circular 90 ° long radius R of 1.5 D bend.
First row A 90 ° Angle, mouth, centered on right-angle intersection with known radius is bending radius R, draw the bend axis, axis and right-angle side intersection of E for midpoint, known to bend diameter interception of A and B two points, with 0 as the center of the circle, the point A and point B lead to bend in the outer arc and arc.
Because the 90 ° long radius elbow is composed of three section and two nodes, a day for two nodes, in order to obtain nodes in order to expand, 90 ° arc and so on can be divided into 8 equal parts, first at the ends of the two nodes, as in the middle of the three section in six section. Outside of each section and then draw the tangent tangent AD for nodes "back", the BC for nodes in the "high", composed of ABCD trapezoid, nodes.
Is in commonly 90 ° long radius elbow an actual operation, according to the number of bend section, determine the equal of 90 °, according to the equal Angle and bending radius and bend diameter, can draw the nodes directly. Nodes can be used in front of the introduced method of parallel lines.
A good nodes, should let out bite allowance, and then use cutting good nodes or section in the template, 'according to the need, the number of draw the shear line on the board, with the hand cut shear shear or oscillating curve, take good longitudinal seam, processing into a short tube with oblique mouth. And then bite on the pressure in the elbow out cross bite, bite, pressure should be paid attention to each section into stand-up at one end, on the other side for the mouth. And should pay attention to the sections of the longitudinal bite stagger.

Pressure good bite, it can be bend group to the assembly. When assembling, should put the AD on the nipple line and the BC on the line with another sub lines to the AD and BC is, to avoid the 90 ° long radius elbow crooked. Bend the elbow joint machine available or steel hammer to joint on the workbench.

Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)

### About yane Yang  Sales Manager

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Joined APSense since, June 7th, 2014, From wenzhou, China. Report this Page

Created on Dec 31st 1969 18:00. Viewed 0 times. Share on APSense