Manufacturing and materials

MANUFACTURING

MANUFACTURING METHODS

Tecnofondi’s dished heads are manufactured by either pressing process (for the so-called press-formed dished heads), or dishing and flanging process (for the so-called flanged formed dished heads).

The dished heads may reach the following dimensions:

Diameter 5000 mm

Thickness 25 mm.

WELDING

If the size of the raw plate does not have the required dimensions, Tecnofondi will carry out a welding process in order to make them suitable for manufacturing.

The welding process is executed by qualified welders, in full compliance with welding process duly define and qualified by the following specifications:

UNI EN 9606-1

UNI EN 15614-1

We wish to emphasize, that unless it is expressly requested, the welds usually are not tested or checked.

If the welds have to be checked by Non Destructive Tests (radiographic inspection) after the forming process, this request must be clearly indicated.

TRIMMING AND BEVELLING OF THE EDGE

The dished heads can be supplied with unfinished or trimmed edge. Trimming is recommended for obtaining the correct height of the dished head and for a perfect flatness of the edges.

It is also possible to rim the dished heads straight flange in order to achieve a better fitting into applied the ferrule up to maximum diameter of 1800 mm and a maximum thickness of 6 mm.

THE PRESS FORMING: SYSTEM AND PRODUCTION

The press forming allows to produce dished heads through the use of standard moulds installed on hydraulic presses; starting from metal disks, in a single dishing operation, press formed heads with the edges requested are obtained.

Tecnofondi is equipped with a wide range of moulds – either with normal, torispherical or elliptical profile – that are assembled on 6 presses with a power between 400 and 1500 tons and with a completely automatic or semiautomatic handling.

Normally working on its own moulds, the company is available to use installations supplied by the customers or to produce customized moulds providing its consulting both for the moulds fabrication and for the product manufacturing.

MATERIAL SUPPLIED BY CUSTOMERS

Any all materials supplied by Customers are treated according the following specifications.The blank (disc of plate that has to be formed) must have ground edges and, if and when welded, the weld must have been made with “x-bevelled” edges, to ensure full and correct penetration.

Further more, in order to remove those parts of such plate that are more subject to suffer working fissures, the weld shall always be carried out after having trimmed the edges of the plates themselves up to a depth of 20 mm (note : this process is not necessary using coils).

The plates must always be assembled in order to follow the direction of the rolling. In the case of supplying square plates (which obtains the blank), their size must always be more than at least 20 mm regarding the expected size of the resulting blank.

It is normal practice to get always the approval from Customer Office of the requested final dimensions of the dished heads before either cutting the blank or the square of plate.

THE ROLLING SYSTEM

This new system enables producing heads through the following phases:

1. disk cutting through circular shearing machine or plasma cutting
2. disk dishing through hydraulic presses equipped with a mechanical hand to obtain a spherical cap.
3. cap flanging through a flanging machine to get end products with customized diameters and profiles.

Inside the production range, Tecnofondi is able to supply all the profiles and the diameters requested up to a thickness of 320 mm and up to a diameter of 5000 mm.

MATERIALS

Generally we can work on materials with a maximum tensile strength of 750 MPa and with a minimum elongation of 22/24%.

Carbon Steel

Coils and dished heads made of carbon steel on stock are in: S235JR according the norm UNI EN 10025-2. The coils also in S355JR or J2.

This material can be hot galvanized at the following conditions:

1 – % maximal Si < 0,03 %
2 – % of Si+2,5P < 0,09 % (In compliance with the French norm AFNOR A (35-503/94)).

We also have a stock of raw material of carbon steel plates S355JR and S275JR according to the norm UNI EN 10025-2.

Stainless steel

Stock of stainless steel heads and sheets are made of AISI 304 and AISI 316 according to the norm ASTM A240.

DO YOU WANT MORE INFORMATION ABOUT MATERIALS AND WORKING FOR DISHED HEADS AND SHEETS?

Fill in this form and our operator will contact you to explain in detail the best solution for your production needs.

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  • Fill in this form and our operator will contact you to explain in detail the best solution for your production needs.

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