How a gored elbow goes together
Round duct changes direction with a gored elbow: the elbow is divided into ring segments — gores — each cut at an angle so that stacked together they sweep through the bend. The gores are cut from sheet or coil, rolled round, and then joined gore-to-gore with a circumferential lock seam. The machine that folds and closes that seam is the gorelocker (you will also see it written gore locker or called an elbow lock-seaming machine). A mechanical seam holds the angle without welding, keeps the galvanised coating intact, and is the standard construction for elbows in galvanised, stainless and aluminium duct. In common practice a 90° elbow uses three to five gores — more gores, smoother sweep, lower pressure loss. The gore blanks themselves come off the cutting bench; see the duct cutting machine comparison for that end of the workflow.
The machines that close the seam
SBKJ builds gorelockers in two drive types — hydraulic and electric — plus the fitting shaper for the small-diameter end of the range. The table lists every machine with the figures from the catalog.
| Machine | Model | Diameter | Material thickness | Max forming speed | Power | Weight |
|---|
| Gorelocker (Hydraulic) | SBEM-1250 | Φ100–Φ1250 mm | Galvanised / black / aluminium 0.4–1.5 mm
Stainless 0.4–1.0 mm | 130 mm/s | 4 kW + 1.25 kW cooling fan | 750 kg |
| Gorelocker (Electric) | SBWT-1000 (A / D) | Φ120–Φ1000 mm | Galvanised 0.4–1.2 mm
Stainless SS304 0.4–0.8 mm | 75 r/min | 1.5 kW×2 + 2.2 kW (A)
1.5 kW×2 + 2.2 kW×2 (D) | 600 kg |
| Gorelocker (Electric) | SBWT-1500 (A / D) | Φ120–Φ1500 mm | Galvanised 0.4–1.5 mm
Stainless SS304 0.4–1.2 mm | 75 r/min | 2.2 kW×2 + 4 kW (A)
2.2 kW×2 + 4 kW×2 (D) | 660 kg |
| Fitting Shaper | SBJQJ-500 | Φ80–Φ400 mm | Galvanised / stainless / aluminium; 0.1 mm (aluminium) as catalogued | — | 3.5 kW | 1500 kg |
Source: SBKJ Product Catalog 2026, manufacturer nameplate specifications. All machines run 380 V / 50 Hz / 3-phase (60 Hz on request). SBEM-1250: 70 L hydraulic oil, flange size 5 / 7.5 / 10 mm, 3000×820×1100 mm. SBWT-1000: 2080×700×895 mm. SBWT-1500: 2450×700×895 mm. Electric models are frequency-controlled.
Hydraulic vs electric — and the A/D variants
Hydraulic (SBEM-1250). One machine covers Φ100–Φ1250 mm and the heaviest mixed-material work: galvanised, black steel and aluminium to 1.5 mm, stainless to 1.0 mm, forming at up to 130 mm/s. It also rolls a 5, 7.5 or 10 mm flange on the gore edge, which suits shops that finish elbow ends in the same pass.
Electric (SBWT-1000 / SBWT-1500). Frequency-controlled at up to 75 r/min, lighter (600–660 kg) and more compact. Each comes in two variants: the A model forms the male and female gore edges; the D model adds the seam-lock closing head (Male/Female/Seam Lock) with a second drive set. If you want one electric machine to take a gore joint from formed edges to a closed seam, specify the D.
Small fittings. Below roughly Φ400 mm the practical companion is the Fitting Shaper SBJQJ-500, which forms the ends of elbows, tees, reducers and branches from Φ80 mm in galvanised, stainless and aluminium.
The deciding numbers are your largest elbow diameter and heaviest gauge: Φ1000 mm tops the SBWT-1000, Φ1250 mm the SBEM-1250, Φ1500 mm the SBWT-1500. For stainless above 1.0 mm the SBWT-1500 (SS304 to 1.2 mm) is the only fit. Round elbows pair with straight spiral duct off a spiral tubeformer; for the full fittings workflow including tees and reducers see the fittings fabrication guide.
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FAQ
What is a gorelocker?
The machine that closes the circumferential lock seam joining the gore segments of a round duct elbow. Gores are cut and rolled first; the gorelocker folds and closes the seam between each pair so the elbow holds its angle without welding. SBKJ builds hydraulic (SBEM-1250) and electric (SBWT-1000/1500) gorelockers.
How is a round duct elbow made?
From gores — ring segments cut at an angle, rolled round, and joined gore-to-gore on a gorelocker with a mechanical lock seam. A 90° elbow commonly uses three to five gores; more gores give a smoother sweep and lower pressure loss.
Hydraulic or electric — which gorelocker?
Hydraulic SBEM-1250: Φ100–Φ1250 mm, mixed materials to 1.5 mm (stainless 1.0 mm), 130 mm/s, rolls a 5/7.5/10 mm flange. Electric SBWT: frequency control, 75 r/min — SBWT-1000 to Φ1000 mm, SBWT-1500 to Φ1500 mm and SS304 to 1.2 mm. Pick by largest diameter and heaviest gauge.
What is the difference between the A and D variants?
A forms the male and female gore edges. D adds the seam-lock closing head (Male/Female/Seam Lock) with a second drive — 1.5 kW×2 + 2.2 kW×2 on the SBWT-1000D, 2.2 kW×2 + 4 kW×2 on the SBWT-1500D.
Can gorelockers run stainless steel?
Yes — SBEM-1250 to 1.0 mm, SBWT-1000 (SS304) to 0.8 mm, SBWT-1500 (SS304) to 1.2 mm. Galvanised, black steel and aluminium run to heavier gauges on the same machines.
What does the Fitting Shaper SBJQJ-500 do?
Forms the ends of small round fittings — elbows, tees, reducers, branches — from Φ80 to Φ400 mm in galvanised, stainless and aluminium, with a 3.5 kW drive. It covers the small-fitting end of the range below the gorelockers.
