TECHNICAL FIELD

The present invention relates to a hot-rolling machine for wire rods and the like.

In greater detail, the present invention relates to a machine for the production of hot-rolled concrete-reinforcing bars, use to which the following description refers purely by way of example without this implying any loss of generality.

BACKGROUND ART

As is known, concrete-reinforcing bars are obtained by subjecting a steel wire rod with a roughly circular section to a process of hot-rolling that brings about a progressive reduction in the nominal section of the wire rod.

Hot-rolling lines that are used for performing this particular metallurgical operation are usually made up of an appropriate number of rolling units that are arranged in cascade one after another along the wire-rod feeding path, so that each rolling unit is able to bring about a slight reduction of the nominal section of the high-temperature steel, wire-rod whilst the latter advances along the hot-rolling line.

Today, each rolling unit of the hot-rolling line is a machine completely separated from and independent of the others, and is usually made up of: a rolling stand provided with two opposed and counter-rotating milling rollers which are arranged one beside the other, locally substantially parallel and tangential to one another, so as to form/delimit in between themselves a groove or throttling within which the wire rod to be hot-rolled is forced to pass; and an electric motor which is mechanically coupled to both of the milling rollers via a large gear reducer so as to be able to drive the two milling rollers in rotation about the respective longitudinal reference axes.

In greater detail, the two milling rollers are fixed on the supporting frame of the rolling stand so as to be arranged horizontally one above the other, parallel and aligned to one another; and the supporting frame is structured so to prevent the two milling rollers from receding with respect to one another when the wire rod to be rolled is forced through the groove or throttling delimited by the two milling rollers, thus being deformed.

Of course, the distance between the rotation axes of the two milling rollers reduces progressively along the wire-rod feeding path so that each pair of milling rollers is able to deform and stretch the wire rod causing a slight reduction of the nominal section thereof.

Given that the nominal wire-rod feeding rate along the hot- rolling line must absolutely not exceed 30-50 metres per second, the only way to increase the productivity per hour of the hot-rolling line consists in dividing/splitting longitudinally the wire rod that is fed at inlet to the hot- rolling line, and then directing each half of the wire rod towards a respective set of rolling units so to hot-roll the two halves of the wire rod simultaneously.

Obviously, the longitudinal splitting of the wire rod with consequent bifurcation of the hot-rolling line can be reiterated a number of times so as to significantly increase the productivity per hour of the plant for production of the concrete-reinforcing bars.

Albeit guaranteeing a considerable increase in the productivity per hour of the plant, the bifurcation of the hot-rolling line causes a significant increase in the amount of machinery involved in the production of the concrete- reinforcing bars, with the increase in running costs that this involves .

The simple doubling of the hot-rolling line, in fact, entails a doubling of the rolling units, with consequent doubling of the extension of the shed that is to house the rolling line, and of the amount of spare parts to be kept always available for ordinary and extraordinary maintenance of the rolling line. In this type of machinery, in fact, maintenance is of a preventive type and usually involves, at regular intervals, all the rolling units of the line.

DISCLOSURE OF INVENTION

Aim of the present invention is to provide rolling units that are more compact than the ones currently commercially available so as to contain the increase in space resulting from the bifurcation of the hot-rolling line.

In compliance with the above aim, according to the present invention there is provided a machine for hot-rolling of wire rods and the like as defined in Claim 1 and preferably, though not necessarily, in any one of the dependant claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

- Figure 1 is a top plan view of a wire-rods and the like hot- rolling machine realized in accordance with the teachings of the present invention, with parts removed for clarity; whilst

- Figure 2 is a front view of the machine shown in Figure 1, sectioned along the line II-II and with parts removed for clarity .

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, reference number 1 designates as a whole a hot-rolling machine for wire rods and the like, which finds particularly advantageous use in the production of concrete-reinforcing bars. The machine 1 is basically made up of a series of rolling units 2 that are arranged in cascaded one after the other along the wire-rod feeding path p so that each rolling unit 2 can deform plastically the high-temperature metal, wire rod b that moves along the path p, causing a slight reduction of the nominal section thereof.

Preferably, though not necessarily, the wire-rod feeding path p is substantially rectilinear and extends horizontally.

Each rolling unit 2 is equipped with a rolling stand 3 that is arranged exactly on the wire-rod feeding path p, and is provided with two opposed and counter-rotating milling rollers 4 which have a substantially cylindrical shape and are arranged one beside the other, locally substantially parallel and substantially tangential to one another, so as to form/delimit a rolling groove or throttling 4a through which the wire rod b to be hot-rolled is forced to pass.

In greater detail, the longitudinal axes L of the two milling rollers 4 are arranged substantially on a same laying plane T (parallel to the plane of the sheet in Figure 2), and are oriented so that the laying plane T is locally substantially perpendicular to the longitudinal axis of the wire rod, i.e. orthogonal to the feeding direction of the wire rod b along the path p, whilst the peripheral surfaces of the two milling rollers 4 are sized so as to form/delimit in between them selves a rolling groove or throttling 4a through which the wire rod b to be hot-rolled is forced to pass.

In the example shown, in particular, the two hot mill milling rollers 4 are preferably, though not necessarily, arranged substantially horizontally position, one on top of the other.

With reference to Figures 1 and 2, each rolling unit 2 is moreover equipped with a mechanical gear reduction unit 5, which is arranged beside the rolling stand 3 and is structured so as to be able to simultaneously drive into rotation the two milling rollers 4 about the respective longitudinal axes L substantially with identical peripheral velocities.

Unlike current hot-rolling machines for wire-rods and the like, the mechanical gear reduction unit 5 of each rolling unit 2 is structured so as to form, with the corresponding rolling stand 3, a single sectional elementary module 2 which is suitably structured for being aligned with other similar sectional elementary modules 2 along the wire-rod feeding path p, and for being mechanically coupled to the immediately adjacent sectional elementary modules 2 so as to compose/form a chain line of rolling units 2, which are reciprocally connected so as to transmit torque in cascade from one another .

In greater detail, each rolling unit 2 is structured so to arrange its own mechanical gear reduction unit 5 adjacent to the mechanical gear reduction unit 5 of the other rolling unit or units 2 present along the wire-rod feeding path p, and the mechanical gear reduction unit 5 is structured so to be mechanically connectable directly to the mechanical gear reduction unit or reducers 5 of the immediately adjacent rolling units 2 so as to be able to form a cascade of mechanical gear reduction units 6 having a disassemblable structure, which extends parallel to the wire-rod feeding path p and is able to transmit the torque autonomously from one mechanical gear reduction unit 5 to another.

With reference to Figures 1 and 2, each rolling unit 2 is preferably, though not necessarily, provided with a respective lower supporting platform 7, which is structured for being rigidly and stably anchored to the floor, and the rolling stand 3 and the mechanical gear reduction unit 5 of the rolling units 2 are arranged on the lower supporting platform 7 one beside the other.

In the example shown, in particular, the lower supporting platform 7 is substantially rectangular in shape and is anchored to the floor with its major side edges arranged locally substantially perpendicular to the feeding direction of the wire rod b along the path p.

The wire-rods and the like hot-rolling machine 1 furthermore comprises a preferably, though not necessarily, electrically- or hydraulically- operated single shared drive unit 8 which is structured so to be mechanically connected to the mechanical gear reduction unit 5 of just one of the sectional elementary modules 2 that form the chain line of rolling units 2 so as to be able to simultaneously drive into rotation the milling rollers 4 of all the rolling units 2.

In other words, the drive unit 8 is structured so to be mechanically connected to just one of the mechanical gear reduction units 5 that form the cascade of mechanical gear reduction units 6 so as to be able to simultaneously drive into rotation the milling rollers 4 of all the rolling units 2.

With reference to Figures 1 and 2, in the example shown, in particular, the two milling rollers 4 of each rolling stand 3 are fixed in an axially rotatable manner on a rigid supporting frame 9, which is structured so as to prevent the two milling rollers 4 from receding with respect to one another when the wire rod b to be rolled passes through the rolling groove or throttling 4a delimited by the peripheral surfaces of the two milling rollers 4, thus deforming itself.

In greater detail, the rigid supporting frame 9 is provided with two side walls 9a that are stably arranged parallel to and facing one another, and the two milling rollers 4 extend straddling the two side walls 9a of supporting frame 9, one beside the another, so that the longitudinal axes L of the two rolls are locally substantially orthogonal to the laying planes of the two side walls 9a, and are preferably arranged substantially horizontally, one on top of the other.

In the example shown, in particular, each milling roller 4 has the two axial ends inserted in pass-through manner and trapped in an axially rotatable manner each within a corresponding side wall 9a of the supporting frame 9, and is shaped so that its central cross section can form/delimit, between the two side walls 9a, the rolling groove or throttling 4a through which the wire rod b to be rolled is forced to pass.

In other words, the two milling rollers 4 are both provided with a roughly cylindrical-shaped central cross section which extends between the two lateral side walls 9a of the rigid supporting frame 9, and are arranged adjacent to one another so that the corresponding central sections are locally substantially tangent to one another and can form/delimit the rolling groove or throttling 4a through which the wire rod b to be rolled is forced to pass.

With reference to Figure 2, in the example shown, in particular, the central sections of the two milling rollers 4 are preferably, though not necessarily, shaped so as to form/delimit a rolling groove or throttling 4a dimensioned for being engaged simultaneously by two wire rods b appropriately spaced apart from one another. Consequently, the wire-rod feeding path p can be engaged simultaneously by two high- temperature metal, wire rods b which move forward parallel to one another.

Preferably, though not necessarily, the rolling stand 3 of each rolling unit 2 is moreover also provided with a preferably electrically- or hydraulically- operated, a device for adjusting the distance between the rollers which is structured so as to be able to approach or move away, on command, the two milling rollers 4 to one another so as to be able to adjust the distance between the longitudinal axes L of the two rolls 4 while maintaining the milling rollers 4 always horizontal and locally parallel to one another.

With reference to Figure 2, in the example shown, in particular, the rigid supporting frame 9 is preferably, though not necessarily, substantially U-shaped and it is rigidly fixed onto the lower supporting platform 7 so that its two side walls 9a overhangingly protrude upwards, in a substantially vertical direction; whilst the mechanical gear reduction unit 5 of the rolling unit 2 is fixed on the lower supporting platform 7, alongside the rolling stand 3, directly facing one of the two side walls 9a of the rigid supporting frame 9.

In greater detail, in the example shown the mechanical gear reduction unit 5 is preferably, though not necessarily, coupled in a rigid and stable, though disassemblable manner directly to the side walls 9a of the rigid supporting frame 9. The lower supporting platform 7, instead, is preferably, though not necessarily, structured so as to enable the rolling stand 3, or rather the rigid supporting frame 9 of the rolling stand 3, to translate horizontally towards and away from the mechanical gear reduction unit 5 in a horizontal direction f locally perpendicular to the two side walls 9a of the rigid supporting frame 9, i.e. parallel to the longitudinal axes L of the two milling rollers 4, so as to be able to uncouple, if need be, the rolling stand 3 from the corresponding mechanical gear reduction unit 5.

With reference to Figures 1 and 2, the mechanical gear reduction unit 5 of each rolling unit 2 instead comprises: a rigid and substantially parallelepiped-shaped, outer boxlike casing 11 which is fixed on the lower supporting platform 7 with a first side wall 11a directly facing the side wall 9a of the rigid supporting frame 9 of the rolling stand 3; and two drive shafts 12 and 13, which extend inside the boxlike casing 11 parallel to a same reference axis R locally substantially parallel to the feeding direction of the wire rod b along the path p, and come out with their distal ends outside of the boxlike casing 11 on opposite sides of the rolling stand 3, once again in the feeding direction of the wire rod b.

In other words, the two drive shafts 12 and 13 are parallel to a same reference axis R locally perpendicular to the laying plane T of the longitudinal axes L of the two milling rollers 4 of the rolling stand 3, and come out outside of the boxlike casing 11 on opposite sides of the rolling stand 3 in the feeding direction of the wire rod b along the path p.

In greater detail, the distal ends of the two drive shafts 12 and 13 sticks out from the two side walls lib of the boxlike casing 11 that are locally substantially orthogonal to the feeding direction of the wire rod b along path p so as to protrude from the sides of the side wall 9a of the rigid supporting frame 9, respectively in front of and behind the rolling stand 3 of the rolling units 2.

In the example shown, in particular, the two drive shafts 12 and 13 are arranged coaxial to the reference axis R, one after the other, and overhangingly stick out from the two major side walls lib of the boxlike casing 11.

The distal end of the main drive shaft 12 is shaped so to be mechanically connectable in an angularly rigid manner to the drive shaft of drive unit 8 or, alternatively, to the distal end of the secondary drive shaft 13 of the immediately preceding rolling unit 2; whereas the distal end of the secondary drive shaft 13 is shaped so to be mechanically connectable in an angularly rigid manner to the distal end of the main drive shaft 12 of the immediately subsequent rolling unit 2.

In the example shown, in particular, the distal end of the main drive shaft 12 is designed to be fitted on the drive shaft of the drive unit 8, or on the distal end of the secondary drive shaft 13 of the immediately preceding rolling unit 2 preferably, though not necessarily, via a first mechanical coupling joint of known type; whilst the distal end of the secondary drive shaft 13 is suited to be fitted on the distal end of the main drive shaft 12 of the immediately following rolling unit 2 preferably, though not necessarily, via a second mechanical coupling joint of known type.

Within the boxlike casing 11, the mechanical gear reduction unit 5 furthermore comprises a gear-set (not shown) preferably, though not necessarily, of epicycloidal type, which is structured to connect the main drive shaft 12 with the two milling rollers 4 of the rolling stand 3, and with the secondary drive shaft 13, so as to transmit the torque to both of the components.

Preferably, though not necessarily, the gear-set of the mechanical gear reduction unit 5 is moreover dimensioned so that the rotating speed of the secondary drive shaft 13 is equal to that of the main drive shaft 12.

Finally, with reference to Figure 1, the drive unit 8 is arranged alongside the first sectional elementary module 2 that forms the chain line of rolling units 2, so as to be aligned with the distal end of the main drive shaft 12 of the mechanical gear reduction unit 5 of the first sectional elementary module 2, and is preferably, though not necessarily, made up of a high-power electric motor 14 and a gear reducer 15 that connects the drive shaft of the electric motor 14 to the distal end of the main drive shaft 12 of the mechanical gear reduction unit 5 of the first sectional elementary module 2.

General operation of the hot-rolling machine 1 for wire-rods and the like is easily inferable from the above description, with no further explanation required.

The advantages deriving from the particular structure of the rolling units 2 are considerable. Firstly, thanks to the provision of the cascade of mechanical gear reduction units 6 with decomposable structure, a single electric motor 14 can simultaneously drive into rotation the two milling rollers 4 of all the rolling units 2 aligned along the wire-rod feeding path p, thus reducing the overall dimensions of the machine.

In addition, the fact that each rolling unit 2 is constituted by a single sectional elementary module 2 greatly facilitates the transportation in loco and subsequent assemblage of the hot-rolling machine 1 for wire rods and the like.

Finally, the fact that each rolling unit 2 is formed by a single sectional elementary module 2 considerably simplifies the design of the machine 1 for hot-rolling of wire rods and the like as a whole, and the production of the individual component parts.

Clearly, changes and modifications may be made to the wire- rods and the like hot-rolling machine 1 as described herein without, however, departing from the scope of the present invention.

For example, in a more sophisticated embodiment, a second shared drive unit (not shown) can be arranged alongside the last sectional elementary module 2 that forms the chain line of rolling units 2 and be connected to the distal end of the secondary drive shaft 13 of the mechanical gear reduction unit 5 of the last sectional elementary module 2.