Tank support — saddle, legs and skirt

The surface is developable and the flat pattern is solved in closed form. Cut the part to the drawing and it fits — the whole uncertainty sits in the K-factor, which belongs to the material and the machine, not to the geometry.

Dimensions are entered as: Outside dimensions. The flat pattern itself is always computed on the neutral fibre — at Ø800 in 3 mm sheet the difference between the inside and the outside dimension is 18.8 mm of developed width, and then the seam does not meet.

En sadel-støtte (vugge) der bærer en vandret trykbeholder. Selve vuggen er en åben halvcylinder, hvis bue følger beholderens runding, båret af to side-plader ned til en bundfod.

Understøtning af tanke og rør — vuggen omslutter beholderens nederste halvdel og fordeler vægten ned i fundamentet. En typisk støtte-del i tank- og rørarbejde.

Smed, industritekniker og skibsmontør — vugge, der bærer en vandret tank eller et rør og fordeler vægten ned i fundamentet.

Konstruktionsstål S235/S355 2–8 mm (vugge + sideplader). Bærende → EN 1090.

Source: Fremstillingsfælder: docs/PLAN-UDFOLDNINGSBIBLIOTEK.md §9.2/§4. Materialer/tykkelser: src/lib/kasse/materialer.ts (DIN 6935 for stål; massefylder og handelstykkelser; springback). Bærende stål: EN 1090 (smede-artikel i src/lib/skoler/indhold/data.ts + kilder.ts).

Vugge-radius — Vugge-radius

Radius på halvcylinderen i mm — skal svare til beholderens yderradius, så lejet passer mod kappen. Den udrullede pladebredde bliver den halve omkreds π·radius.

Bredde — Vugge-bredde

Vuggens udstrækning langs beholderaksen i mm. Bliver højden på den udrullede vugge-plade.

Højde — Støtte-højde

Samlet højde fra fod til vugge i mm. Styrer side-pladerne og fodens placering — disse skæres som separate flade dele.

Step by step with compass and square — in cardboard first, in sheet metal after.

1. 01Udvikl kun vugge-pladen her: en halvcylinder (180°-bue) ruller ud til ét plant rektangel (parallel-linje).
2. 02Tegn rektanglet: bredden = π·radius (den halve omkreds langs buen), højden = vugge-bredden. Læg en limflap langs den ene lange søm.
3. 03Del buen (bredden) i 6 felter à 30° og afsæt valse-stationerne som lodrette hjælpelinjer — de styrer rulningen så krumningen bliver jævn.
4. 04Rul pladen til en halvcylinder med den ønskede radius og saml langs limflappen, så åbningen vender opad og danner lejet.
5. 05Skær foden (bundplade) og de to side-plader ud som separate flade dele.
6. 06Montér side-pladerne mellem fod og vugge, og fastgør vuggen ovenpå, så lejet matcher beholderens runding.

Kun selve vugge-pladen udfoldes som ét rektangel — fod og side-plader er flade dele, der skæres og samles for sig. Kontrollér at vugge-radius matcher beholderens yderradius, ellers ligger tanken ikke an i hele buen.

• ·Sadlens bredde = R_kontakt·θ (buelængden), IKKE π·r — π·r gælder kun ved θ = 180°.
• ·Langhuller til varmeudvidelse: Δ = α·ΔT·L (S235 12·10⁻⁶/K, 1.4301 16·10⁻⁶/K) — ellers spænder tanken op ved temperaturskift.
• ·Bærende støtte er omfattet af EN 1090; sadeltallene (slidplade, kontaktvinkel) er vejledende, indtil de er verificeret mod EN 13445-3 kap. 16.

The words and formulas the trade uses for a flat pattern. The symbols are the same throughout Discebo: α is the bend angle in degrees, R the inside bend radius, t the sheet thickness and K the K-factor — all in millimetres.

Flat pattern (development)

The part's surface laid out flat as one continuous cutting outline — the way the sheet looks BEFORE it is bent or rolled. Only a developable surface can be unfolded exactly; a doubly curved surface cannot be laid flat without stretching the material.

Flat length

The flat length the part must be cut to so the dimensions come out right once it is bent. It is either the sum of the outside dimensions minus the bend deductions, or the sum of the flat legs plus the bend allowances — both routes must give the same number.L = Σ(udvendige mål) − Σ(BD) = Σ(flade ben) + Σ(BA)

Bend allowance

The length of material that sits in the bend itself, measured along the neutral fibre. The bend allowance is always positive and is added to the flat legs.BA = (π/180) · α · (R + K · t)

Bend deduction

The amount subtracted from the sum of the outside dimensions, because the two outside dimensions between them count the corner twice. Here the bend deduction is taken as POSITIVE and subtracted; DIN 6935 writes the same quantity as the compensation value v with the opposite sign.BD = 2 · OSSB − BA

Outside setback

The distance from the theoretical outside corner point in to where the bend starts. Above 90°, tan(α/2) is clamped to at most 1 per DIN 6935, so the number does not explode towards 180°.OSSB = tan(α/2) · (R + t)

Compensation value v to DIN 6935

The standard's own way of writing the same corner loss: the flat length is a + b + v, where v is negative. Our bend deduction is therefore the same quantity with the opposite sign — never flip one without the other.L = a + b + v ⇒ v = −BD

K-factor

Where the neutral fibre sits in the sheet, given as a fraction of the sheet thickness. DIN 6935 writes the correction factor k, which applies to the neutral line in the form (R + t·k/2); the American CAD convention writes (R + K·t), so K = k/2.k = 0,65 + 0,5 · log₁₀(R/t), k ≤ 1,0 ⇒ K = k/2

Neutral fibre

The layer in the sheet that is neither stretched nor compressed when the part is bent. The flat pattern is always computed on the neutral fibre — which is why it matters whether the drawing's dimensions are inside or outside.

Bend angle

The angle the material is turned through, not the angle between the legs. The bend angle is 180° minus the included angle, so a square corner is 90° and a seam fold is 180°.α = 180° − åbningsvinklen

Inside bend radius

The radius on the inside of the bend. It is set by the tooling and the material, not by the drawing — too small a radius cracks the part in the outer fibre.

Sheet thickness

The thickness of the material. It enters every single bend allowance, so sheet delivered 0.2 mm thicker than ordered shifts the flat length at every bend.

Fold line

The line on the flat pattern where the part is to be bent. It is drawn but never cut through — in a laser file it therefore sits on its own layer.

Test bend

A strip of known raw length, bent in the material and the tooling that production will use. Measure the two outside legs afterwards and the bend deduction and K-factor can be worked back. The machine's own measured bend table beats any table.BD_målt = (A + B) − L₀

DIN 6935 covers only cold bending of flat products in structural steel. Stainless, aluminium, copper, brass and titanium zinc are not included — there the formulas are an extrapolation, and a test bend in the actual material settles it.

41 fields. The starting values belong to the figure itself — they live in one place in the code, so the tool, the share link and the smoke test can never disagree about what «default» means.

A preset sets every dimension at once. The name is often the word the part goes by in the workshop — the library's search knows them all.

Read them before the part is cut. They are here because they cannot be calculated away — not as legal text, but as craft.

• The figure DOES NOT SIZE. It supplies cutting patterns and check dimensions — not load capacity. Material thicknesses, weld sizes, anchor bolts and foundation must be calculated by whoever is responsible for the structure.
• The saddle figures (saddle spacing A ≤ 0.2·L, wear plate θ + 12°, saddle width b ≥ 1.56·√(R·t), wrap angle ≥ 120°) are GUIDANCE-ONLY geometry and must be verified against EN 13445-3 ch. 16 or ASME VIII App. G before being used as requirements.
• The vessel itself is not in the figure. If it is pressure-bearing above PED 2014/68/EU's class limits, both the vessel and its support are certified equipment in accordance with EN 13445, and the support's effect on the shell must be verified.
• The anchor bolts' edge distance and pitch are calculated according to the repo's own workshop rule (edge distance ≥ 2 × Ø, pitch ≥ 3 × Ø). It is not a standard: load-bearing anchors are sized in accordance with EN 1993-1-8 and the anchor manufacturer's ETA.
• The support skirt's buckling stability (shell buckling) has not been calculated. A tall, thin skirt can fail by buckling long before the material yields — h/D is given as a key figure, but the limit is given in the structural code.
• Welding data is not covered: throat thickness, joint preparation, electrode, preheating, weld build-up and testing belong in a welding procedure to EN ISO 15614. The weld lengths here are pure geometry.
• Lifting eyes, lifting brackets and hanger plates are NOT part of the figure. Certified lifting gear with documented WLL must not be issued from a development tool.
• Purchased profiles (angle, square tube) and standard tank legs are supplied as commercial goods — they are not included in the development, the parts list or the sheet layout, only in the welding schedule.