JUGAO Project Engineering Solutions: A Complete Technical and Engineering Solution, Not Just a Quote

Start with one combined operating case

From enquiry to an engineering response

01Define the jobDrawing, material certificate, thickness, width and finished ID / OD

02Specify the W12 caseExact model, pre-bend at both ends, support, unloading and pass plan

03Verify the resultAgreed trial, measurement positions, tolerances and signed disposition

Define the cylinder before selecting the machine

Six dimensions are easily confused in a plate-roll enquiry. A drawing should identify the finished outside diameter D_o, finished inside diameter D_i, plate thickness t, mid-thickness diameter D_m, axial cylinder length or rolling width B, and the developed length running around the circumference. Width B and developed length are perpendicular dimensions; interchanging them can produce the wrong machine selection and the wrong blank.

Cylinder geometry and quotation vocabulary

D_o — finished OD D_m — mid-thickness D_i — finished ID

D_oFinished outside diameter and its inspection stage.

D_iFinished inside diameter; do not assume a catalogue “minimum diameter” uses this basis.

D_mIdeal mid-thickness diameter, not a verified plastic neutral layer.

tSpecified plate thickness plus its permissible and measured variation.

BAxial cylinder length, corresponding to the plate width through the rolls.

LDeveloped length in the rolling direction, including the agreed treatment of seam gap, bevel, trimming and shrinkage.

Axial width and developed length are perpendicular

B — axial width through rolls ↕L — rolling direction / developed length →

Do not swap B and L.B affects the loaded roll span. L is the blank direction that wraps around the circumference and must include the agreed seam and trimming allowance.

What the four rolls do—and why pre-bending is separate

On the JUGAO W12 product page, the upper roll is described as the main driven roll, while the lower and side rolls move hydraulically. The upper and lower rolls clamp the plate; the side rolls establish the bending geometry; and a tilting bearing arrangement is listed for unloading the formed cylinder. These descriptions explain a process route, but they do not define the capacity of one ordered configuration under every material and diameter condition.[1]

Four-roll arrangement: load path, not a capacity certificate

Clamp

The upper and lower rolls grip and feed the plate. Confirm the material surface, plate alignment and permissible marking.

Upper / lower clamp; left / right side rolls establish curvature

Bend and support

The active side roll, roll spacing, force, deflection and workpiece support all affect the developing curvature and flat ends.

From flat plate to measured cylinder

1. Load and alignConfirm rolling direction, edge preparation and axial position.

2. ClampGrip the plate between upper and lower rolls without substituting clamping for forming.

3. Pre-bend end ABring the first edge toward the required curvature and control its residual flat.

4. Main rollForm the central length in controlled passes while supporting the growing shell.

5. Pre-bend end BReverse or reposition as required; verify both ends rather than assuming symmetry.

6. Compensate and unloadAdjust for measured springback, then confirm support and tilting-bearing clearance.

Near each plate edge, the rolls cannot create exactly the same contact condition as in the central region. Pre-bending is therefore a distinct capacity question. The supplier should state the maximum pre-bending thickness for the combined case and the residual flat achievable at each end, including where that flat is measured. A main-rolling thickness is not automatically a two-end pre-bending thickness.

Two plate ends need two residual-flat readings

End Aflat f_A

formed middle length

End Bflat f_B

Record pre-bend setup AConfirm target curvatureRecord pre-bend setup B

What the public JUGAO table says—and what it does not

The following values are transcribed from the JUGAO main-site W12 table. They are public page fields, not measurements from this project and not proof that every value in one row is simultaneously achievable for the same material, workpiece, two-end pre-bend and one-pass cycle.[1]

The page does not define whether the 245 MPa field is an exact reference value, a limit or another rating convention. It does not state tensile strength, elongation, grade or rolling direction. Nor does it define whether “Min roll diameter” means finished ID, OD, mid-thickness diameter or a diameter before unloading. Those items belong in the signed technical response.

An 800 mm drawing callout is not enough

Assume only for terminology that a drawing specifies a finished outside diameter D_o of 800 mm and a uniform thickness t of 25 mm. Ideal concentric geometry gives:

This is a geometry example, not a W12-25X2000 trial, blank-length instruction or capacity guarantee. Treating D_m as a pure-bending neutral-layer approximation would give an outer-fiber engineering strain of approximately t/D_m = 25/775 = 3.23%. Real forming also involves yield behavior, hardening, movement of the plastic neutral layer, thickness variation, roll contact and springback. Directly cutting πD_m would additionally ignore seam gap, bevel, trimming, the actual neutral layer and weld shrinkage.

Thickness sensitivity is real, but a teaching formula cannot select the machine

For a rectangular plate section per unit width, an ideal elastic-perfectly plastic material and fully plastic bending, a teaching approximation is:

Illustrative ideal moment per metre of plate width

20 mm

24.5 kN·m/m

25 mm

38.3 kN·m/m

The equation explains why thickness cannot be treated as a small linear change. It omits hardening, roll lever arms, contact and friction, side-roll travel, upper-roll deflection and actual curvature. It must not be used to calculate hydraulic pressure, machine tonnage, minimum rolling diameter or a supplier guarantee. Selection requires the complete material curve, target diameter, axial width, both-end pre-bending and the actual machine geometry.

Why the teaching formula stops before machine selection

Includedσ_y, t and a rectangular section per unit width

Not includedHardening, friction, roll contact and lever arms, deflection, pass plan and actual curvature

Use the result forExplaining thickness-squared sensitivity

Do not use it forHydraulic pressure, tonnage, minimum diameter or capacity guarantee

Material strength and springback change the result

Springback is not one percentage

Outokumpu states in a roll-bending context that springback varies between steel groups and that changing grade and/or sheet thickness often requires machine adjustment to obtain the correct shape.[2] Yield strength, tensile strength, hardening response, elongation, thickness and rolling direction should therefore travel with the RFQ. They cannot be replaced by “mild steel,” “stainless,” or a catalogue thickness alone.

A peer-reviewed study on thick Invar 36 plate also reports springback sensitivity to radius, thickness and upper/lower-roll clamping force within its investigated range.[4] That evidence is useful for identifying variables, not for assigning a springback rate to carbon steel, aluminum or a JUGAO machine.

Springback variables to record for the trial

Grade and heatYield / tensile propertiesHardening and elongationThickness and rolling directionTarget radiusClamping force and pass plan

A material-specific limit stays material-specific

Industeel specifies D_i ≥ 30t, plate temperature above 10°C and rolling force approximately twice that for S355 for its Creusabro® 4800 wear-resistant steel.[3] For that grade at t = 25 mm, the material document gives D_i ≥ 750 mm. This is not a universal steel rule and it is not a W12 capacity statement. The JUGAO table’s 800 mm is also undefined as ID or OD, so the numbers cannot simply be compared.

Creusabro® 4800: a material-specific rolling envelope

Manufacturer condition	Applies to
Di ≥ 30t	Creusabro® 4800 in the cited Industeel file
Plate temperature >10°C	The same specified material
Rolling force about 2× S355	Industeel comparison, not a W12 measurement

For t = 25 mm, D_i ≥ 750 mm is a material constraint for that grade only.

Measure springback after unloading the sample

Under loadForming curvature and roll settings

After unloadingMeasured free shape and target comparison

Adjust the pass plan using the actual material and sample result.

Publicly visible vs. required in the order

The JUGAO W12 product description identifies roll functions and public model-row values. To turn that starting information into a project solution, tie the selected machine and delivered options to one material, one drawing and one measurable acceptance case.

The W12 configuration is one connected engineering case

Material + blankStrength, thickness, full axial width

Roll arrangementClamp, side-roll movement, pre-bend at A and B

JUGAO W12Named model and delivered configuration

Support + unloadingShell weight, supports and tilting-bearing path

AcceptanceControlled diameter, flats, stage and measurement plan

Support, unloading, seam preparation and measurement belong in the capacity review

As the shell closes, gravity can pull it out of plane and impose loads that were not present when the plate was flat. Ask whether side or overhead supports, a feed table, crane or purpose-designed lifting tools are required. Confirm the maximum workpiece weight, the tilting-bearing sequence, the clear path for the closed cylinder and any collision envelope. The public W12 page lists tilting-bearing unloading but does not publish workpiece weight, minimum unloadable length or support options for the case considered here.[1]

Support and unloading path for the closing shell

Feed and alignSide / overhead supportClosed-shell clearanceTilting-bearing unload

The inspection plan should match the fabrication plan. Record whether diameter and roundness are accepted before or after tack welding, final welding or stress treatment. Measure at agreed circumferential positions and at both axial ends plus the middle. Inspect the residual flat at both plate ends, the bevel or seam gap, axial straightness and any local closing mismatch. The drawing or contract—not this article—must supply the tolerances.

Sample inspection map: axial stations and clock positions

End A

12369

Middle

12369

End B

12369

Copy-ready RFQ fields

1. Finished geometry: controlled D_o or D_i, axial length B, thickness and tolerance, developed-length basis, roundness and straightness.
2. Seam: butt-joint type, bevel, root gap, trimming plan and maximum residual flat at each end.
3. Acceptance stage: open shell, tack-welded, welded or post-treatment; inspection temperature and tools.
4. Material: grade and standard, heat certificate, measured R_e or R_p0.2, R_m, elongation, thickness tolerance and rolling direction.
5. Machine: exact W12 model and formal configuration; confirm whether thickness, full width, minimum diameter and both-end pre-bending apply together.
6. Diameter basis: ID, OD or another basis; finished or before unloading; applicable measurement locations.
7. Pre-bending: maximum thickness under this case, residual-flat limit at both ends and measurement method.
8. Forming plan: expected passes/re-rolls and the method used to compensate springback and roll deflection.
9. Handling: side/top supports, feed table, crane and lifting tools, workpiece weight and unloading clearance.
10. Safety and supply: actual guards, emergency stops, operator position, infeed/outfeed zone, training and destination documentation.

Blank sample acceptance record

U.S. safeguarding: verify the delivered machine and the work method

OSHA 29 CFR 1910.212 requires guarding against hazards including the point of operation, ingoing nip points and rotating parts, and specifically lists forming rolls and calenders among machines that usually require point-of-operation guarding.[5] OSHA Publication 3170 discusses in-running nip points, feeding and unloading, control placement and safeguarding factors for roll-forming and roll-bending machines.[6]

For a U.S. installation, review the actual machine, braking and stopping behavior, speed, plate thickness, support equipment, loading/unloading method, emergency stops, operator position, training and local requirements. This article does not certify a W12 configuration to OSHA, ANSI, CE or any other jurisdictional requirement.

Configuration review before U.S. use

Delivered guardsStop / brake behaviorControls and E-stopsSupport equipmentOperator trainingLocal requirements

Frequently asked questions

Sources

1. JUGAO, W12 4 Rollers Hydraulic Plate Rolls — public product description and model table; accessed September 29, 2026.
2. Outokumpu, Forming of Stainless Steel — bending and roll-bending discussion of springback, grade and thickness; accessed September 29, 2026.
3. Industeel / ArcelorMittal, Creusabro® 4800 Processing Data — material-specific rolling conditions on page 4; accessed September 29, 2026.
4. Wang et al., “Study on four-roller roll-bending forming and springback of thick Invar 36 alloy plate,” Journal of Plasticity Engineering 25(4), 2018, 59–64 — research boundary and variables; accessed September 29, 2026.
5. OSHA, 29 CFR 1910.212, General Requirements for All Machines — guarding, points of operation, ingoing nip points and forming rolls; accessed September 29, 2026.
6. OSHA Publication 3170, Safeguarding Equipment and Protecting Employees from Amputations — roll-forming and roll-bending safeguarding guidance; accessed September 29, 2026.