Method for manufacturing a crystallizer for continuous casting

A method for manufacturing a crystallizer for continuous casting comprising the following steps:

• i)—obtaining a first rectilinear tubular element, which is monolithic in one piece and made of a first metal material constituted of copper or a copper alloy with a prevalence of copper, the first rectilinear tubular element having a first pre-set length, and being delimited by a first lateral wall having a first pre-set radial thickness;
• ii)—obtaining a second rectilinear tubular element, which is monolithic in one piece and made of a second metal material identical to or different from the first metal material, the second rectilinear tubular element having a second pre-set length and being delimited by a second lateral wall having a second pre-set radial thickness;
• the step ii) being carried out so as
• a)—to obtain the second tubular element wider than the first tubular element,
• b)—to obtain a ratio between the size of the second radial thickness of the second tubular body and the size of the first radial thickness of the first tubular body ranging between 0.75 and 1.2;
• iii)—providing, on an outer lateral surface of the first tubular element or on an inner lateral surface of the second tubular element, one or more radially opened grooves;
• iv)—inserting the first tubular element within the second tubular element, so as to couple the first and second tubular element together maintaining between them a pre-set radial play;
• v)—co-extruding the first and second tubular elements together by drawing them together through an annular die having previously inserted into the first tubular element a mandrel that reproduces in negative the shape that is to be imparted to a casting cavity of the crystallizer to be obtained and then passing the mandrel with the first and second tubular elements through the die, which is configured for shaping the lateral wall of the second tubular element with a shape that is to be imparted to a tubular body of the crystallizer to be obtained;
• wherein
• vi)—during the step v) at least some of the said one or more radially opened grooves are left empty and, owing to the ratio between the size of the second radial thickness and the size of the first radial thickness are not filled by any metal material in consequence of the drawing step, but are instead closed radially, so as that said tubular body of the crystallizer to be obtained is formed as a monolithic body by mechanical coupling in a continuous manner and coaxially to each other the first and second tubular elements together, forming at the same time one or more conduits in the lateral wall of the tubular body.