Pipe onto an Elbow: flat pattern

A round branch set onto a segmented bend, on its outside or on its side: the branch unrolled with the saddle that fits the gores. A round branch set onto a segmented bend, on the outside of the bend or on its side: the branch unrolled with the saddle that fits the gores it lands on.

Open the pipe onto an elbow in SheetMorph

Configurations

A worked example

The on the outside configuration with the sizes SheetMorph opens with, in mm. One plate: the branch unrolled, with its saddle cut to the gores of the bend: 1 part, 2 seams.

The flat pattern of this example: outlines to cut, with the lines to mark and any holes. Open it in SheetMorph for the dimensioned drawing and the files to cut it.
For the shop
Blank, the rectangle the plate is cut from630.4 mm × 276.5 mm
Length of cut, every outline and hole1771.0 mm
Sizes on the mid-thickness surface (used for the pattern)
Diameter of the bend401.00 mm
Diameter of the branch201.00 mm
Bend
Radius to the centreline600.00 mm
Bend angle90.00 °
Gores, the two end gores included5
Turn at each joint22.50 °
Branch
Position round the bend from End A45.00 °
Along the centreline of the bend from End A471.24 mm
Length along its axis450.00 mm
Girth of the plate631.46 mm
End of the branch above the wall of the bend, on its axis249.50 mm
Plate blanks
P1 Branch, long630.45 mm
P1 Branch, wide276.51 mm
Pattern
Plates1
Triangular facets64
Pattern extent X630.45 mm
Pattern extent Y276.51 mm
Developed area165,656 mm²
Total cut length1771.02 mm
Longitudinal seam length249.50 mm

How it is developed

Parallel-line development (unrolled cylinder) onto a segmented bend. This is a triangulated approximation: the curved surface is divided into small flat triangles, each laid out at its true size. The finer the division, the closer the pattern is to the surface; SheetMorph states the deviation it found.

Checked before it can be exported

Every pattern SheetMorph draws is checked against the 3D part it comes from. For this example:

Assumptions

Limits of this module

Conventions

Coordinate system. The part stands on the Z axis with End A at Z = 0. Angles round the axis are measured from +X toward +Y, counter-clockwise seen from +Z.

Divisions and thickness. A circle is divided into 4N equal chords. Sizes are inside, mid-thickness or outside sizes; the pattern is developed on the mid-thickness surface and the views show the sizes as entered.

Bend. The bend is a segmented (lobster-back) bend that turns in the XZ plane from +Z toward +X, with End A at the origin; its radius is to its centreline, and its gores are counted with the two end gores, which are half gores. It is shown by a ring at each joint and is not developed here: use the miter bend for its gores.

Branch. The axis of the branch crosses the centreline of the bend at the position entered, an angle round the bend from End A. On the outside it points straight away from the centre of the bend; on the side it is square to the plane of the bend, toward +Y. End A of the branch is its saddle and End B its square end; its length is measured along its axis from the centreline of the bend.

Change the sizes to your own in SheetMorph, check the drawing, add seam and flange allowances, and export DXF, PDF, SVG, CSV or G-code. Check every pattern against your own standards before cutting.

Open the pipe onto an elbow

Other pipe ends and nozzles