There are hundreds of manufacturers of tanks, silos, pressure vessels, truck tanks, and metal rolls components all over the world. Most of these companies need to produce or source dished ends of various types, sizes, and specifications to complete their products.
These dished ends are produced in different ways. A common method is called dishing and flanging, a technique that provides manufacturers with the flexibility, high productivity, and quality of the end product required in today’s competitive market. A dishing and flanging line can form heads of any shape, be it flat, conical, standard, torispherical, semielliptical, or ellipsoidal. Material thicknesses range from 5 to 60 mm in the cold condition and up to 80 mm in the hot condition; diameters range from less than 1 meter up to more than 8 m.
The dishing and flanging occurs in two sequential operations that each require specific machinery: the dishing of the blank and the forming of the plate edge.
The Dishing Process
Once the plate has been cut to size in a circular shape, the resulting dish is formed under a Faccin PPM press that, with multiple hits distributed over the entire surface, will crown the plate.
To make different types of dished ends and different diameters, the PPM dishing press must be equipped with a set of dies shaped with different radii. The dishing process might require several hours depending on the plate dimensions and the material but can be automated by using Faccin’s numerically controlled manipulator MA. Faccin’s presses with CNCs can handle more than 10 axes and run automatically for hours. Another important factor in the dishing process is speed. Double-speed can be added and greatly increase the production output.
The structure of a dishing press is subject to material fatigue. Faccin Presses with an “HPT design” can resist fatigue better. Two beams – top and bottom – are connected to the uprights with the use of hydraulic pretension tie rods which better resist the continuous stress, in comparison to seam welding or bolts, by giving more elasticity to the structure.
The Flanging Process
After the dishing comes the forming of the edge, which will allow the dished end to be welded to the tank body to support the pressure inside. This operation may cause lamination of the plate. Faccin machines are powerful to do the flanging in a minimum number of passes, causing a minimum thinning of the dished end.
Less thinning of the plate means a more profitable production for producers, because they do not need to use thicker plates to guarantee the minimum thicknesses.
To reduce the lamination, Faccin produces machines with the correct geometry, enough power in the rotation, and good control of the movements of the flanging roll. They are equipped with a pressure control that helps the operator by preventing the squeezing of the plate. With an efficient gap control CNC, Faccin machines allow even inexperienced operators to execute the flanging with the minimum number of passes.
Faccin’s flanging machine also feature controls that always allow for the best contact of the rolls with the plate. This includes the ability to tilt the flanging and shaping rolls. The electric and hydraulic units make the difference between Faccin’s flanging machines and low-quality machines in the market. The hydraulic unit allows the movements to be proportional and simultaneous which permits the movement of the carriage that holds the dished end to the rest of the axis.
Dished ends can be flanged with or without a center hole. Faccin’s flanging machines for dished ends without center hole have a closed structure that permits the blocking of the disc with two clamping cylinders. For these flanging machines to have a smooth movement of the carriage, no matter how high the clamping force is, they are equipped with the latest generation friction-free technology that consists of ball rails for the carriage movement and ball screws for the precise positioning.
Once the dished end is formed, manufacturers must match tolerances for circumference and depth. Faccin’s Flanging machines can be equipped with machining arms to chamfer the edge of the plate and adjust the dished end height. Faccin’s advanced machines have a sophisticated system for measuring the dished end circumference to make it easier for the operator to deliver a perfect product.
Dishing and flanging machines are machines with many important technical aspects that should be properly evaluated. Selecting the right machine can make the difference between a successful and unsuccessful business.
For more information,
Website www.faccin.com
