IT202100008258A1 - APPARATUS AND PROCEDURE FOR ROLLING A METALLIC PRODUCT - Google Patents

Description

Description of the invention entitled:

"APPARATUS AND PROCEDURE FOR ROLLING A METALLIC PRODUCT"

FIELD OF APPLICATION

The present invention relates to an apparatus and to a relative method for rolling a wire rod to obtain a metal wire which can be used for example in the aeronautical, medical, automotive, construction and construction fields. construction, industry, agriculture and livestock, small metal parts, fences or other.

The present invention is mainly applied, even if not exclusively, in the post-treatment processes of metallic material coming essentially from hot rolling processes, to obtain particular properties. mechanical resistance and workability, according to the specific intended use.

STATE OF THE ART

? It is known that long products such as wire rods, which are obtained from hot rolling processes downstream of a continuous casting, are often used in the subsequent supply chain as starting products to obtain final products with dimensional characteristics and properties? desired mechanics.

For example, rolling apparatuses or drawing apparatuses are known which use, as input metal product, wire rods wound up in coils and arranged on suitable feed reels, to obtain a final product having a different and desired size and section.

With particular reference to the rolling apparatuses, these include a plurality of of units rolling mills, each of which is equipped with at least one pair of rolling rollers, or rings.

The rollers are mutually arranged so as to define a passage channel through which, in use, the metal product being processed is passed.

The passage channel between a unit? of processing and the subsequent decreases progressively until you reach the final thickness/dimension that you want to give to the metal product, which will have? at the end of the process a form of metal wire. Currently these post-treatments of the rod obtained from previous hot rolling passages are mainly carried out cold, with limited reductions in section, both overall and for each passage, due both to the state of the material and to the fact that an excessive number of passages would increase the work hardening on the final product.

Also, during cold rolling, the metal product must be constantly lubricated with powder lubricants which contaminate the environment. To partially reduce this environmental contamination, expensive suction, purification and disposal systems are used, which however, in addition to weighing on the overall costs of the system, do not completely solve the problem.

At the end of the process it is therefore necessary to spread the product obtained in special annealing ovens to reduce its fragility. This step increases the manufacturing times and does not always allow you to obtain a product with the properties? desired mechanics.

Also, currently, due to the type of process ? very difficult, or even impractical, the rolling of wire rods made of steel with a high carbon or cobalt content, titanium and its alloys, hardened nickel-based superalloys, hardened cobalt-based superalloys and other materials also obtained by sintering powders, to obtain respective metallic threads. In fact, the product could undergo cracking during processing or phenomena of brittle breakage.

Is there therefore a need? to perfect an apparatus and method for rolling wire rods which can overcome at least one of the drawbacks of the prior art.

In particular, an object of the present invention ? that of realizing a rolling apparatus which, starting from wire rods made of steel with a high carbon or cobalt content, titanium and its alloys, hardened nickel-based or hardened cobalt-based superalloys, and other materials also obtained by sintering the powders , and having a nominal diameter of between about 3mm and about 8mm, is capable of making wire having a nominal diameter of between about 0.5mm and about 1.5mm, eliminating the problem of hardening of the material.

Another object of the present invention ? that of realizing such an apparatus which does not require the presence of an annealing furnace at the end of the line.

An additional purpose? that of developing a wire rod rolling process that is capable of achieving a significant reduction in thickness even on materials that typically present work hardening problems.

Another purpose? that of realizing an apparatus and a relative process for rolling wire rods to produce metal wires which requires a low energy input, which does not release contaminants into the environment and which is therefore eco-sustainable.

To obviate the drawbacks of the prior art and to obtain these and further objects and advantages, the Applicant has studied, tested and implemented the present invention.

DISCOVERY DISPLAY

The present found ? expressed and characterized in the independent claims. The dependent claims disclose other characteristics of the present invention or variants of the idea of the main solution.

In accordance with the aforementioned purposes, an apparatus for rolling a metal product, initially in the form of wire rod with an initial thickness between 3mm and 8mm, to produce a metal wire with a final thickness between 0.5mm and 1.5mm, includes a plurality of units rolling mills arranged aligned along an axis for processing the aforesaid metal product.

According to one aspect, the apparatus comprises a main reheating furnace arranged upstream of a first of said units. of lamination, and a plurality? of units of secondary heating alternated along the axis of processing to the unit? rolling and configured to bring/return the metal product to a suitable processing temperature.

In accordance with embodiments, ? a process for rolling a metal product is provided which provides for making the metal product available in the form of a rod having an initial thickness of between about 3mm and about 8mm.

The method also provides for the metallic product to be advanced continuously and in sequence through said plurality of elements. of units rolling mills arranged aligned along an axis for processing the metal product which operate a progressive reduction in the thickness of the metal product until it is in the form of a metal wire having a final thickness between about 0.5mm and about 1.5mm.

In one aspect, before the metal product is advanced through a first of said units? of lamination, the metal product? passed through a main reheat furnace which takes the metal product from room temperature to a suitable processing temperature in the relevant unit? Laminating. Also, when advancing between a unit? rolling and the next, the metal product is passed through units? secondary heating systems which keep the metal product at the optimum processing temperature.

ILLUSTRATION OF THE DESIGNS

These and other aspects, characteristics and advantages of the present invention will become clear from the following description of embodiments, provided by way of non-limiting example, with reference to the accompanying drawings in which:

- fig. 1 ? a schematic side view of a rolling apparatus in accordance with embodiments described herein;

- fig. 2 ? a top view of fig. 1 ;

- fig. 3 ? a schematic front view of two pairs of rollers arranged in orthogonal planes.

For ease of understanding, identical reference numerals have been used wherever possible to identify identical commonalities in the figures. It should be understood that elements and features of one embodiment may be conveniently combined or incorporated into other embodiments without further specification.

DESCRIPTION OF EMBODIMENTS

Will it be done? now reference in detail to the possible embodiments of the invention, of which one or more? examples are illustrated in the attached figures by way of non-limiting example. Even the phraseology and terminology used here? for non-limiting example purposes.

A rolling apparatus 10, in accordance with the present invention, is configured to roll a metal product P in the form of a wire rod to obtain a metal wire having a lower thickness and certain mechanical characteristics.

Here and in the continuation of the description and of the claims, the term metallic product P refers to the product being processed which initially ? in the form of wire rod and at the end of the procedure implemented with the rolling apparatus 10 ? in the form of a wire.

The metallic product P ? made of a material selected from a group including Titanium and its alloys, a sintered material based on Cobalt and its alloys, a stainless steel enriched with high percentages of Chromium, a titanium enriched stainless steel, a steel with a high or low of carbon.

By way of example, the materials considered can be a material obtained by sintering powders (C-Cr-Mo-W-Co-V), Titanium and a Titanium alloy, a Superalloy of Titanium Gr 21 (Mo-Nb-Mo-Al) , a hardened Nickel-based superalloy (Co-Cr-Mo-Nb), a hardened Cobalt-based superalloy (Ni-Cr-W), and others.

The metal product P, in the form of a wire rod, has an initial thickness Si of between about 3mm and about 8mm and, in the form of a metal wire, it has a final thickness Sf of between about 0.5mm and about 1.5mm. It should be noted that the initial and final thickness dimensions of the metal product should in no way be considered as limiting the applicability? of the present invention.

According to embodiments, the metal product P can? have a round, oval, square, rectangular, hexagonal, octagonal, half-round or similar or comparable shape in section.

In the case of a metal product P with a round section, the thickness Si, Sf is substantially equivalent to the diameter of the circular section.

According to embodiments, the rolling apparatus 10 comprises a plurality of of units rollers 11, each of which is equipped with a roller 12 having at least one pair of rollers 13.

The units? rollers 11 are arranged aligned along an axis X for processing the metal product P. In the embodiment shown in figs. 1-2, are there four units? of lamination 11. However configurations of apparatus with a greater or lesser number of unity? of lamination 11. The number of units? of rolling 11 ? however, less than that of traditional cold systems, on equal terms? of total reduction ratio of the metal product P between input and output.

In the embodiment described here, each rolling device 12 comprises four pairs of rollers 13 arranged alternately on two transverse planes with respect to each other.

In particular, a first and a third pair of rollers 13 lie on a vertical plane while a second and a fourth pair of rollers 13 lie on a horizontal plane, substantially orthogonal to said vertical plane.

The pairs of rollers 13 are arranged in sequence with vertical-horizontal alternation.

In possible embodiments, the planes of arrangement of the pairs of rollers 13 can be mutually inclined at an angle other than 90?.

The pairs of rollers 13 define between them a passage channel 14 (fig.

3) with decreasing light along the processing axis X and within which the metal product P slides pushed/pulled by the rollers 13.

Passage channel 14 ? essentially horizontal.

In particular, each rolling device 12 makes it possible to obtain a specific reduction step R.

The reduction step R ? defined by the ratio between the cross-sectional area of the incoming metal product P and the cross-sectional area of the metal product P outgoing from the rolling device 12.

The reduction step R ? also defined by the relationship between the speed? of the metal product P at the input and the speed? of the metal product P leaving the rolling device 12.

Each rolling device 12 ? characterized by a reduction step R percentage preferably between 58% and 75%, more? particularly between about 60% and about 68%. The overall reduction, considered between input and output of the machine, can? however, even get up to about 99%.

According to embodiments, the reduction pitch R of the first rolling device 12 is greater than that of the subsequent ones. In a possible embodiment, the reduction steps R of the rolling devices 12 other than the first are almost equal to each other.

According to embodiments, each rolling device 12 comprises a single drive member 15 connected in a manner per se? known to the pairs of rollers 13 to make them rotate. Each pair of rollers 13 ? rotation with speed? different in order to make the lamination fluid as a result of the? elongation of the metallic product P due to the reduction of the section.

The rolling apparatus 10 comprises a main reheating furnace 16 arranged upstream of the first unit? of rolling 1 1 and a plurality? of units of secondary heating 17 alternated along the axis of machining X to the unit? of rolling 11 and through which passes the metal product P being processed to be brought, or brought back, to a suitable processing temperature Tw.

The presence of the main heating furnace 16 and of the units? of secondary heating 17 allows to obtain reduction steps R greater why? when is the material of which ? Once the metal product P is formed, it requires less energy to be deformed.

Furthermore, by heating the metal product P, powder lubricants are not needed, which tend to contaminate the working environment. The main reheat furnace 16 ? configured to bring the metal product P for the first time from ambient temperature Ta to a processing temperature Tw.

According to embodiments, the main reheat furnace 16 and the units secondary heating systems 17 are of the induction type.

The main oven 16 and the units? secondary heating devices 17 preferably operate at very high frequency and low power and have an adjustable temperature, and can therefore be used for many materials and applications. However, it cannot be excluded that the main oven 16 and/or the units secondary heating systems 17 can also operate at low frequency. By very high frequency we mean a range in the order of about 400-500 kHz. These frequencies are suitable for non-magnetic materials such as titanium, hardened nickel, stainless steel, hardened cobalt and others.

By low frequency we mean a range in the order of about 6-10 kHz. These frequencies are suitable for low and high carbon steel-like magnetic materials.

According to embodiments, the operating frequency of the main furnace 16 and the units? secondary heating 17 pu? be fixed or adjustable.

The power of the main reheating furnace 16 ? greater than the power of the individual units? of secondary heating 17. For example, the power of the main heating furnace 16 ? about 5-8 times the power of a single unit? secondary heating 17.

For example, in the case of induction technology, the main heating furnace 16 can have a power of about 75kW and the individual units? of secondary heating 17 a power of about lOkW.

According to possible embodiments, at the inlet and/or outlet of the main reheating furnace 16 and of the units heating devices 17, the rolling apparatus 10 comprises temperature sensing devices configured to sense the temperature of the metal product P and a unit? plant that receives the temperature data and manages the power of the main heating furnace 16 and of the units? secondary heating 17.

The lamination? advantageously made at temperatures that are maintained quasich? constants.

In a hot plastic deformation the temperature and the state of stress imposed on the metal are such as to lead to a rapid recrystallization during the process (dynamic recrystallization) in order to avoid the establishment of a state of hardening of the metal. Recrystallization replaces the deformed grain crystal structure with a new set of stress- and distortion-free grains.

Based on the materials to be laminate, the treatments to be carried out and the properties? to obtain, the selected working temperature Tw is in a range between about 700?C-800?C up to about 1200?C.

According to embodiments, the rollers 13 are made of special low conductivity materials. thermal in order to reduce the pi? the heat released by the metal product P during processing is possible. For example, the rollers 13 may be made of sintered materials such as low conductivity sintered ceramic alloys. thermal.

Upstream of the main heating furnace 17, the apparatus 10 comprises one or more? reels 18 on which the metal products P in the form of wire rod are wound into coils. The reels can be of different types based on the weight of the coils to be produced and/or on the temperatures at the exit from the rolling process.

Downstream of the last unit? of rolling 1 1 ? there is a winding device 19 configured to receive the metal wire produced and to wind it into coils.

According to possible embodiments, the rolling of the metal product P can take place in a controlled atmosphere with noble gases, such as Argon or Nitrogen.

Embodiments described here also refer to a rolling process of a metal product P.

The process provides for making the metal product P available in the form of a rod having an initial thickness Si of between about 3mm and about 8mm.

Furthermore, the process provides for continuously advancing the metal product P through the plurality of elements. of units rolling mills 11 arranged aligned along the processing axis X of the metal product P which reduce the thickness of the metal product P until it is in the form of a metal wire having a final thickness Sf between about 0.5 mm and about 1, 5mm.

According to one aspect of the above process, before the metal product P is advanced through the first unit? of rolling 11 , the metallic product P ? passed through a main reheating furnace 16 which brings the metal product P from ambient temperature Ta to a suitable working temperature Tw. Also, when advancing between a unit? rolling 11 and the next, the metal product P is passed through the units? secondary heating systems 16 which return the metallic product P to the working temperature Tw.

According to embodiments, the metal product P is initially in the form of wire rod and ? wrapped on one or more coils arranged on respective reels 18.

The metal product P, which enters in the form of wire rod, is unwound, straightened and introduced, for example by means of suitable driving rollers, into the main reheating furnace 16.

The metal product P crosses, in a continuous way, the unit? of lamination 11, all? inside each of which the thickness of the metal product P is decreased by a reduction step R percentage between 58% and 75%, more? in particular between about 60% and about 68%.

According to a possible embodiment, the crossing path at the interior of the main heating furnace 16 and of the units? of secondary heating 17 performed by the metallic product P ? rectilinear and the tension control, determining the sliding value, is controlled with an electronic system in order to increase the permanence time between the units? rolling 1 1 maintaining the same speed? of progress. For example, ? It is possible to foresee that the metal product follows a zig-zag path.

It is clear that modifications and/or additions of parts or phases can be made to the rod rolling apparatus and method described up to now, without thereby departing from the scope of the present invention as defined by the claims.

In the claims that follow, the references in brackets have the sole purpose of facilitating the reading and must not be considered as limiting factors as regards the scope of protection implied in the specific claims.

Claims (8)

1. Rolling apparatus (10) of a metal product (P), initially in the form of wire rod with an initial thickness (Si) between 3mm and 8mm, to make a metal wire with a final thickness (Sf) between 0, 5mm and 1.5mm, said rolling apparatus (10) comprising a plurality of units rolling mills (11) arranged along a processing axis (X) of said metal product (P), characterized in that it comprises a main reheating furnace (16) arranged upstream of a first of said units? of lamination (11) and a plurality? of units of secondary heating (17) alternated along said machining axis (X) to said units? rolling mill (11) and configured to bring/return said metal product (P) to a suitable processing temperature (Tw) for rolling in the relative unit? of rolling (11). 2. Rolling apparatus (10) as in claim 1, characterized in that each of said units? roller (11) comprises a rolling device (12) having at least one pair of rollers (13) which define between them a passage channel (14) with decreasing light along the processing axis (X), having an initial transversal dimension between about 3mm and about 8mm and a final cross-sectional dimension between about 0.5mm and about 1.5mm. 3. Rolling apparatus (10) as in claim 1, characterized in that the maximum power of said main reheating furnace (16) is? about 5-8 times the maximum power of a single unit? heating circuit (17). 4. Lamination apparatus (10) as in claim 2, characterized in that each lamination device (12) ? characterized by a percentage reduction step (R) comprised between 58% and 75%, preferably between 60% and 68%. 5. Process of rolling a metal product (P) comprising: - make the metal product (P) available in the form of a rod having an initial thickness (Si) between 3mm and 8mm, - continuously advance the metal product (P) through a plurality? of units rolling mills (11) arranged aligned along a processing axis (X) of said metal product (P) which reduce the thickness of said metal product (P) until it is in the form of a metal wire having a final thickness (Sf ) between 0.5mm and 1.5mm, characterized in that before said metal product (P) is advanced through a first of said units? rolling mill (11), said metal product (P) ? passed through a main reheating furnace (16) which brings said metal product (P) from an ambient temperature (Ta) to a suitable working temperature (Tw), and which when it advances between a unit? rolling (11) and the next, the metal product (P) is passed through unit? secondary heating systems (17) which return said metal product (P) to said suitable processing temperature (Tw). 6. Process as claimed in claim 5, characterized in that said metal product (P) continuously passes through said units? of rolling (11), within each of which the thickness of said metal product (P) is decreased by a percentage reduction step (R) comprised between 58% and 75%, preferably between 60% and 68%. 7. Process as in claim 5 or 6, characterized in that the lamination of said metal product (P) takes place at a temperature of almost constant and approximately equal to the recrystallization temperature of the material constituting said metallic product (P). 8. Process as in any one of claims from 5 to 7, characterized in that said metallic product (P) ? made of a material selected from a group including titanium and its alloys, a sintered material based on cobalt and its alloys, a stainless steel enriched with high percentages of chromium, a titanium enriched stainless steel, a steel with a high or low of carbon.