Cyclone Separator: flat pattern

A cyclone dust collector from its barrel diameter, to Stairmand or Lapple proportions or your own: barrel, cone, roof, inlet duct and gas outlet tube. A cyclone dust collector from its barrel diameter, to the Stairmand or Lapple proportions or your own: the barrel with the inlet opening, the cone, the roof with the hole for the gas outlet, the inlet duct and the gas outlet tube.

Configurations

• Stairmand (high efficiency). Inlet 0.5 D high and 0.2 D wide, gas outlet 0.5 D across reaching 0.5 D below the roof, barrel 1.5 D and cone 2.5 D high, dust outlet 0.375 D across.
• Lapple (general purpose). Inlet 0.5 D high and 0.25 D wide, gas outlet 0.5 D across reaching 0.625 D below the roof, barrel and cone each 2 D high, dust outlet 0.25 D across.
• Custom proportions. Every size given: the inlet, the gas outlet and how far it reaches down, the barrel and cone heights and the dust outlet.

A worked example

The stairmand (high efficiency) configuration with the sizes SheetMorph opens with, in mm. Five plates: the cone, the barrel with the inlet opening, the roof, the inlet duct and the gas outlet tube: 5 parts, 8 seams.

How it is developed

Development of rolled plates (barrel, cone, tube) and flat and folded plates (roof, inlet duct). This is an exact development: the surface unfolds without stretching, so the pattern closes exactly.

• The barrel unrolls to a rectangle as long as its girth, with the inlet opening a notch cut down from its top edge: as deep as the inlet is high, and as wide as the arc between where the duct’s two walls meet the barrel.
• The cone unrolls to part of an annulus; it and the barrel are cut on the side away from the inlet.
• The roof is flat with the hole for the gas outlet tube in its middle; its edge runs round over the inlet opening, where it meets the top of the duct.
• The inlet duct is one plate folded at its four corners. Its outer wall touches the barrel and is cut square; its inner wall is cut where it meets the barrel, and its top and bottom are cut to the curve of the barrel.
• The proportions are Stairmand’s high-efficiency set, each a multiple of the barrel diameter, listed under Sizes.

Checked before it can be exported

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

• Surface connectivity (passed): 254 facets form the body of the cyclone, open at the dust outlet and the inlet, and the gas outlet tube through its roof: every edge inside a part joins exactly two facets, every open edge one (V - E + F = 0).
• Developed edges equal true 3D lengths (passed): 762 facet edges compared between the 3D surface and the flat pattern (max deviation 4.26e-11).
• Shared edges and seam closure (passed): 249 internal edges are shared vertex-for-vertex between adjacent facets; 4 seam(s) have mating edges of equal true length (max deviation 2.27e-13).
• Developed facets consistently oriented (passed): All developed facets are counter-clockwise (outside face up); none is mirrored or degenerate.
• Developed area equals surface area (passed): Facet area in 3D and in the flat pattern agree (difference 2.85e-7).
• Cut outlines closed and non-overlapping (passed): 5 closed outline(s); no outline crosses itself or another outline.
• HOLE-OUTLET lies within its plate (passed): 128 points of the hole compared with the edges of the plate; its developed area is 71129.2858.

Assumptions

• The pattern is developed on the mid-thickness surface; inside or outside sizes are converted to it by the thickness.
• Curves are chains of chords between division points.
• No seam, lap, weld-preparation or pressing allowance is added.

Limits of this module

• Only a tangential inlet of rectangular section is modelled; involute (scroll) inlets, axial inlets and inlet vanes are not.
• No airflow, efficiency or pressure drop is worked out: the proportions are geometry only. Size a cyclone for its duty from a reference or a supplier.
• The dust outlet is left open: a rotary valve, flap, dust bin or hopper below it is not modelled, nor any support legs or flanges.
• The gas outlet tube passes through the roof with no flange or collar, and no wear liner is added to the barrel at the inlet.
• Curves are chains of straight chords between division points.
• No seam, lap, weld-preparation or pressing allowance is added, and plates are not nested onto stock sheets.

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.

Body. The cyclone stands on the Z axis with the dust outlet, the foot of the cone, at Z = 0. The cone rises to the barrel, the barrel to the roof, and the gas outlet tube passes down through the roof to its foot inside the barrel.

Inlet. The inlet is a rectangular duct that enters along the barrel: its outer wall touches the barrel on +X, its top is level with the roof, and it runs toward -Y, so the air turns counter-clockwise seen from above. Its length is measured along it from the line where its outer wall touches the barrel.

Proportions. Stairmand and Lapple are the two standard proportions found in air pollution control references, each size a multiple of the barrel diameter D. They are starting points: the efficiency and pressure drop of a cyclone depend on the dust, the flow and the speed at the inlet, which are not worked out here.

Plates. The barrel is one plate with the inlet opening cut in its top; it and the cone are cut on the side opposite the inlet. The roof is flat, with the hole for the gas outlet tube. The inlet duct is one plate folded at its four corners, its end against the barrel cut to the barrel.

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.

Other hoods, plenums and cyclones

• Canopy: An extraction hood: a skirt round a rectangular opening, four sloping sides and a collar for the duct, in the middle or against a wall.
• Canopy, Round Collar: An extraction hood for a round duct: a skirt round a rectangular opening, a rectangle-to-round sloping part and a round collar, in the middle or against a wall.
• Plenum Box: An open box folded from one blank with a row of round spigots on its back or a side: the box with every hole marked, and the spigots unrolled.
• Inlet Box Scroll: The scroll of a fan inlet box laid flat: its straight sides and arc unrolled, each line across as deep as the box is there.