PRODUCT REVIEWS
Dished head forming in focus
VIDEO
“ When faced with the choice to continue outsourcing dished heads for your tank and pressure vessel production or to start making them in-house , it is important to decide beforehand on the ideal process technology which balances manufacturing costs , production time , tooling costs and energy consumption ,” the Faccin Group told ISMR .
“ In principle , there are two methods , coldand hot forming . For both options , there is the deep drawing process line and the two-step process of dishing and flanging . The deep drawing method is the best choice for repetitive pressed heads ; the tools are tuned for each size and operating costs can therefore be calculated on the serial production of heads . Cold or hot processing is the result of evaluating material type , geometrical dimensions and the cost of the equipment . Hot forming requires less force but more energy consumption in the forming process . Cold forming is normally used for LPG tank heads and similar applications for light-walled tanks ,” it continued .
The dishing and flanging method has been used all over the world as it is a versatile process which can handle a wide range of plate qualities , thicknesses and diameters . Boldrini , part of the Faccin Group , has developed the experience to generate high performance levels from this process line-up over many years .
“ At Faccin Group , we cover cold forming and can manufacture heads from 2mm up to 80mm in 360 Mpa material ( elliptical shape ). In hot forming , we have reached a plate thickness of 210mm for a 5000mm diameter elliptical shape used for secondary pressure vessels in nuclear plants ,” explained Boldrini
“ Since capacity is not limiting , it is vital to evaluate production cost efficiency in terms of process time and thinning of the plate from the flat to the final head . The thinning factor is significant as the material used nowadays in the market has a higher tensile strength than materials used decades ago . Thinning , understood as thickness reduction due to the dishing and flanging process , has a drastic impact on the mechanical properties of the vessel . High thinning levels will mean higher material purchase costs and lower quality of the final product ,” it continued .
Boldrini has also developed design expertise in the geometry of the axis and hydraulic drives which underpin the efficiency of its dishing presses , manipulators and flanging machines .
“ We recently designed and manufactured a flanging machine ‘ without a centre hole ’ and with CNC controls . This machine is designed to flange Titanium heads in hot forming and can process a wide range of possible diameters . We are currently building a new dishing press , for the same customer , for cold and hot forming , with a special advanced hydraulic design designed to cut energy consumption levels by up to 50 % and increase overall speed by 12 %. Our policy is to assist clients from the feasibility study up to the final run-off at their plant , including support for equipment lay-out and workshop personnel training ,” concluded the manufacturer . n
. boldrini . com
Twin-head tube bending
Unison manufactures a range of all-electric twin-head CNC tube bending machines . Part shapes range from simple U-bends to more complex parts such as wheelbarrows frames , bus seats and shopping trolleys / carts .
Its five-axis machine incorporates a centre rotator ( the fifth axis ), suitable for the high-speed manufacture of wheelbarrows or seat frames where symmetrical shapes are required . It is available with weld seam detection units ; end formers ; tube marking equipment and bar code tube batch readers . Common applications include automotive , furniture and agricultural .
“ Our U-Bender cell is a bespoke two-axis production cell used to manufacture ladder rungs with various options including loader ; tube separator ; tube centraliser & measurer ; servo-electric pick & place system and ejection chute ,” Unison told ISMR .
Unison ’ s eleven-axis bending machine has the added benefit of multi-stack , multi-radius functionality . It is available with flattening and punching units ; weld seam detection units ; end formers ; tube marking equipment and bar code tube batch readers . n
ISMR July / August 2021 | sheetmetalplus . com | 69