EP1892048A1

EP1892048A1 - Method and apparatus for dynamic surface cleaning and straightening for steel wire rod and/or bars

Info

Publication number: EP1892048A1
Application number: EP07015876A
Authority: EP
Inventors: Claudio Bernardinis
Original assignee: AWM SpA
Current assignee: AWM SpA
Priority date: 2006-08-24
Filing date: 2007-08-13
Publication date: 2008-02-27
Also published as: ITUD20060202A1

Abstract

A method and a corresponding apparatus for dynamic straightening and surface cleaning : of steel wire rods and/or bars. The rolled-element (1) is subjected to a dynamic action, caused by the spindle-like orbital rotation (1.1) in the region between the two eccentric rotating bushes (3, 4). Upstream (2) and downstream (3) there are optional roller traction assemblies to produce the advancement of the rolled element. These assemblies are actuated, controlled and adjusted with respect to each other by virtue of a suitable transmission of motion with a differential device. Likewise, the two eccentric rotating bushes (3, 4) are moved by the motor (8) and by the corresponding drive with differential device (9). The iron scale and other impurities (7), which separate from the outer surface of the rolled element (1.1), due to the bending deformation (centrifugal effect) and to an aerodynamic effect, are collected in the container (6). The rolled element, when it exits from the region of spindle-like orbital rotation, exits in a straightened condition and with a clean outer surface.

Description

Field of Use

The present invention relates to a method for dynamic straightening and surface cleaning of a wire rod and/or profiled elements and to the corresponding apparatus. The steel in rods and/or the profiled elements with a round cross-section produced by steelworks are provided in the form of large coils which weigh approximately 2000 to 5000 kg; these materials require adequate straightening and surface cleaning before being used, particularly in the manufacture of electro-welded metal nets and/or three-dimensional cages used in the building sector and in industrial prefabrication.
Furthermore, due to technical requirements of application, the hot-rolled material provided in the form of coils must also be cold-stressed to the proximity of its yield strength, in order to strain-harden its surface to improve its mechanical strength characteristics, and its surface must be cleaned of iron scale (iron oxide) and/or other impurities to facilitate subsequent operations (for example electro-welding et cetera).
The aim of the invention is to provide an apparatus or a machine which is capable of performing simultaneously the three functions for treating the profiled steel, i. e.: straightening, simultaneous strain-hardening, and the cleaning of iron scale and/or other impurities that are present. The method is based essentially on the fact that along a clearly delimited portion, the rolled bar is subjected to a "spindle-like" orbital rotation with respect to the input and output advancement axis. This determines the alternating stretching of the peripheral parts of the cross-section of the profiled element, uniform stretching deformation and compression of the material along its entire outer surface with respect to its neutral axis, causing the sought strain-hardening of the material and its surface cleaning, with separation of iron scale and/or other impurities by virtue of the centrifugal force applied to the rolled steel part (no interventions with direct contact with the mechanical elements on the surface are therefore necessary) and by aerodynamic effect in contact with the air.

Prior art

In the prior art it is known, in the metal and steel working sectors, that hot-rolled parts and profiled elements which have a round section up to a certain diameter are wound in coils in order to facilitate their transport, handling and storage. These coils are arranged on appropriately provided unwinding units and the rolled material is subjected to the straightening step by means of appropriately provided units with rollers which act directly on the outer surface, producing straightness, subsequently cleaning the surface with descaling and/or brushing machines and/or by means of treatments in chemical pickling baths, and finally cutting to size said rolled parts.
In particular, current mechanical systems for surface cleaning of profiled elements only provide partial cleaning (approximately 80-90%), which then, during subsequent processes, causes separations into the environment of fine particles which are dangerous for operators, who are forced to work while wearing protective masks. Furthermore, said poorly removed surface impurities cause difficulties in performing surface welds, reducing the quality of the final product. Moreover, the small and particularly hard iron scale flakes which separate from the profiled elements during the processes damage the mechanical elements of the machines and of the equipment, causing longer times dedicated to cleaning them and more frequent ordinary and extraordinary maintenance.
Moreover, surface cleaning of rolled steel elements by chemical treatment in appropriately provided pickling baths, in addition to greatly slowing the production cycle, causes entirely different costs in environmental terms for the disposal of the used chemical solutions.
If the produced profiled steel is to be subjected to galvanizing, chromium plating, et cetera, it must be absolutely and perfectly free from iron scale and other impurities.
Therefore, with current systems various disadvantages have been observed: sanitary ones, ones related to the healthiness of the work environment, and economic ones, because for perfect cleaning of the profiled elements it is necessary to arrange them on multiple machines, greatly slowing the production speed, therefore with a higher incidence on production cost, more dirt on the machine tools, with consequent frequent interventions for preventive and extraordinary maintenance, and a higher pollution rate if chemical pickling systems are used.

Summary of the invention

It has been thought to overcome the drawbacks observed in the cleaning of hot-rolled profiled steel by using a new method of the dynamic type (therefore not a chemical one) and the corresponding cold treatment machine which have the following characteristics:

producing, by spindle-like rotation of the straight steel rolled product, a pulling force and a consequent controlled elongation along the entire section,
producing, by centrifugal force caused by the eccentric rotation of the profiled element, the dynamic bending of the profiled element and the consequent slight elongation of the material during its rotation, the separation of iron scale in the form of small flakes from the outer surface of the material being treated, performing better cleaning than known methods;
an automatic machine which can be managed with computerized control methods capable of having, in each instant, control of the stresses and rotation parameters to which the profiled element is subjected;
the machine has a large housing for protection and collection of the dust produced by the separation of the iron scale flakes from the outer surface of the profiled element, avoiding their scattering into the work environment; aspirators are not needed since the aerodynamic effect caused by the rotation of the profiled element itself is used;
the possibility to perform the spindle-like rotation of the profiled element without touching the material with any mechanical means in the region of maximum radius of rotation: this rotation is generated with the aid of two particular rotating bushes, which are controlled automatically, one for input and one for output in the spindle-like rotation region. These bushes are of the eccentric type: the profiled element enters the bush centrally with respect to the rotation axis and exits from it with a slight deflection, and vice versa, in order to adjust the inclination of the bend of the spindle shape. The same spindle-like orbital rotation of the profiled element can also be provided by means of a single special rotating bush and a bush of the fixed type;
the eccentric axis of said rotating bushes of the eccentric type can be movable and controllable on command (to facilitate the initial step of spindle-like orbital rotation of the rolled part and of control during normal steady-state operation);
the bar, in its advancement, orbits in a spindle-like manner between the special bushes, does not rotate about itself and is not subjected to torsion except minimally and in any case to a controllable extent;
the stretching step of the profiled element is adjusted on command both by acting on the rotation speed of the bushes which determine the spindle-like rotation and by acting, by adjusting it on command, on the input and output speed of the profiled element in said spindle-like rotation region;
both upstream and downstream of the present machine, it is possible to use traction devices with a controlled speed, which are provided with load cells in order to keep under control the traction stress on the spindle-like rotating profiled element;
both upstream and downstream of the present machine, it is possible to provide for the use of optional profiled element straightening devices;
the profiled steel can be treated by spindle-like rotation in series in the same direction of rotation or in the opposite direction;
the profiled steel in output from the treatment machine can be equally rewound and/or drawn with a die and/or cold-rolled by means of appropriate cassettes and/or into straight wire rods cut to size.

Essence of the invention

The aim of the invention is achieved according to the characteristics of the main claim and/or of any other claim cited in this patent text by means of the method and corresponding apparatus for dynamic straightening and surface cleaning for wire rods and/or bars made of steel, originally hot- and/or cold-rolled in the form of coils.
The present process is meant to perform on the advancing hot steel rolled element, in a single operation, quick straightening, excellent surface cleaning of iron scale that is present and/or other impurities, and a dynamic traction stress in order to achieve a controlled elongation. In summary, the machine applies to the rolled element the following controlled functions: alternating rotary stretching of the outer layers of the section (the profiled element does not rotate about itself); axial stretching, centrifugal effect, aerodynamic effect.
To achieve this, a single machine has been conceived which uses automatic mechanical systems which are managed, regulated and controlled by means of computerized methods, in order to be able to intervene at any time to ensure constant quality and uniformity of the treated product. In practice, to control the advancement speed of the bars in cooperation and coordination with the two rotation speeds of the two rotating bushes.
It is known that the material, in particular hot-rolled steel, is provided on its surface with an oxide known as iron scale, which hinders subsequent processes (for example electro-welding) and has the effect of continuously releasing flakes which damage the machines and also contaminate the work environment.
Therefore, it has been thought to provide a process for treating the material, which usually arrives from cylindrical coils, after an optional first straightening and a pusher traction assembly, toward an automatic machine which does not use chemical means but only the dynamic action of the material itself, which is turned in a spindle-like manner between the two bushes, which rotate at a mutually adjustable distance from each other, said bushes being actuated, regulated and controlled in their rotation by suitable automatic systems.
In said particular rotating bushes, the rolled element is made to pass through a central hole, which is coaxial to the advancement direction, entering one and exiting from the other. The material, which arrives horizontally along the advancement and rotation axis of the first bush, is immediately inclined slightly in order to deflect it eccentrically in its rotation with respect to the incoming axis and is subsequently passed through the second rotating bush, which is coaxial to the preceding one, first at an angle (skewed) and then centrally (i. e., in the opposite manner with respect to the first bush). Since both bushes rotate about their own axis and the angular velocity of each bush can be controlled, this determines a spindle-like rotation of the profiled element between the two bushes. The profiled steel between the two rotating bushes is curved with a large central bend, and in this point the rotation radius depends on its orbital rotation velocity, on its mass and on its controlled elongation. The rolled part, in its advancement through the rotating bushes, does not rotate about itself and is not subjected to torsion except minimally and in any case to an extent which can be controlled.
At the output of the second bush, the material is straight and most of all clean. The material of the profiled element in the spindle-like rotation step, due to centrifugal force, in fact tends to elongate and bend along its entire outer surface, facilitating the separation of iron scale in more or less small flakes. This is due to the fact that the bar does not rotate about itself and is therefore subjected to alternating stretching and compression in the peripheral parts of the section of the rolled element. The particles of iron scale and/or other impurities, by separating from the profiled element, are propelled at speed (centrifugal force) against the internal surface of the container or housing and can be collected by gravity and/or, in the case of the smallest, by aerodynamic effect caused by the spindle-like rotation of the profiled element itself, and aspirated and conveyed into an appropriate centrifugal collector.
The material, as it exits from the machine according to the present invention, is perfectly clean on its outer surface and is ideal and ready to be further processed on machines (for example electro-welded, bent, et cetera) or to be subjected to other protective treatments (such as for example galvanizing, chromium plating, et cetera).
The process for dynamic treatment of the material or the apparatus conceived according to the present invention allows to control constantly the stretching of the material during the spindle-like rotation step by virtue of appropriately provided systems for managing and adjusting the two traction elements with load cells in the input to and the output from the two rotating bushes, thus determining the advancement speed of the wire rod being treated. Simultaneously, the two rotation speeds of the respective input and output bushes are managed and adjusted, controlling by means of appropriately provided sensors the breadth of the spindle-like rotation radius of the profiled element being treated.
The machine provided according to the present method uses, in the region of orbital rotation of the rolled element, a suitable housing or protection shaped like a container for collecting the flakes of iron scale and of other impurities which detach from the surface of said rolled element due to an aerodynamic and/or centrifugal effect, which has a dual function: avoid the dispersion of the flakes into the environment, facilitating their collection, and protecting the operators.
Ultimately, by keeping under control the parameters cited above, obviously positive advantages are achieved on the hot- or cold-rolled material are achieved, obtaining first of all better surface cleaning of the profiled element, faster straightening and uniform and controlled stretching of the material, as prescribed by modem standards of mechanical design and calculation in applications in building structures in general.
In a possible variation to the present invention, said hot-rolled profiled material can be subjected to multiple stresses in series, i. e., by making it pass through multiple machines in line, which make it turn by orbiting in a spindle-like manner in the same direction or in the opposite direction, or through multiple successive rotating and non-rotating bushes which have identical or different pitches.
In another technical solution, at the end of the present treatment, the rolled element can be again rewound into coils and/or drawn by means of suitable dies, and/or cold-rolled with suitable rolling assemblies and/or collected and reduced to straight bars cut to size and/or processed directly by bending it into the most disparate geometric shapes.
Another variation to the machine, in a simplified essential form which does not have input and/or output roller traction assemblies, might comprise only the rotating input bush and rotating output bush assembly and the corresponding covering housing. This is sufficient to be able to perform the spindle-like orbital rotation of the metallic laminated element between the two bushes and to obtain a stretched, straight and clean product.
Another variation of the present invention consists in using capstan systems instead of any traction or guiding elements with rollers upstream and/or downstream.
A further application of the present invention consists in providing said machine which imparts a spindle-like orbital rotation of the rolled element which uses a single rotating bush, which has a controlled eccentricity, and another bush of the fixed type.
A further variation to the machine consists in using equivalent systems for making the rolled element orbit in a spindle-like manner, such as for example systems which use a rotating magnetic field, an oscillating magnetic field and or and/or other rotating and/or orbiting systems.
Furthermore, the present invention is suitable to be used as a dynamic test on metallic wires or bars.

Description of drawings

An embodiment according to the present invention is illustrated by way of preferential non-limiting example in the two accompanying drawings, wherein:

Figure 1 is a side view of the machine required for processing the hot- and/or cold-rolled profiled element, suitable to straighten it, clean its surface and stretch it slightly if required. The central part of the machine is enclosed in an appropriately provided container for collecting and retaining the surface flakes of iron scale and/or of other impurities which separate from the profiled element during spindle-like rotation;
Figure 2 is a plan view of said machine of Figure 1.

As can be seen from the accompanying figures, a preferred embodiment of the machine is shown which corresponds to the method for treating the hot- or cold-rolled profiled steel (1, 1.1, 1.2). The machine is arranged downstream with respect to the device for unwinding coils of steel bar, which is simply drawn (2) in a straight manner and guided toward the input rotating bush assembly (3).
Said assembly has a particular bush, which rotates about itself by virtue of suitable motion and actuation means, and is provided with a hole for the insertion of the metallic profiled element in a central position with respect to its rotation axis, and with an exit hole which is slightly eccentric (in this manner, the profiled element is forced to exit with a slight inclination). The profiled element is then forced to enter the second rotating bush (4) through the hole which is slightly eccentric with respect to the final exit hole, which is coaxial to its own rotation axis. The second rotating bush is also motorized and actuated in its rotation. Finally, the profiled element (1.2) is drawn (5) in a straight manner for subsequent processes. The two traction assemblies, (2) upstream and (5) downstream, are driven by the motor (10) and the motion is adjusted by the differential unit (11), and therefore it is possible to control and adjust the advancement of the rolled element in input and in output with respect to the spindle-like orbit region of the rolled element (1.1).
The essence of the present invention lies in the particular rotating input and output bushes (3, 4) and in the spindle-like rotation of the rolled element (1.1) at a rotation speed which is controlled and managed automatically in order to allow constant control of the speed of spindle-like rotation of the profiled element, of the breadth of the radius of the rotation to which the profiled element is subjected, and the consequent extent of the tension for drawing the profiled element during its spindle-like rotation. All these factors are constantly controlled and managed by virtue of suitable automation means which are known to those skilled in the art. The motor (8) in fact transmits its motion to the assembly of the rotating bush (4) and at the same time to the rotating bush (3) through a suitable adjustable differential unit (9) in order to vary and control the spindle-like orbital rotation of the rolled element.
The rolled element, during treatment, does not rotates about itself, and therefore alternating stretching and compressions of the peripheral part of the section are determined.
Furthermore, the two rotating bushes (3, 4), or just one bush, can move at a mutually adjustable distance. The rotation axes of both bushes are coaxial or not.
The machine, particularly in the central region (i. e., the region where the metallic profiled element is made to turn in a spindle-like manner), is enclosed in a housing-like container (6) for protection and safety of the operators, which is meant to collect the iron scale flakes (7) which separate from the surface of the rotating profiled element and are subjected both to centrifugal force and to the effect of stretching the material and to the consequent aerodynamic effect.
Small iron scale flakes (7) are collected both by gravity and by suction generated by the aerodynamic rotation effect of the profiled element (1.1) inside said container. This avoids the dispersion of iron scale dust into the work environment.
The profiled element, during the spindle-like rotation, is subjected to a centrifugal force and to a drawing tension between the two rotating bushes (3, 4), which determines the chosen elongation (improving the mechanical characteristics of the product), and the separation from the outer surface of the iron oxide in the form of small flakes, which are then collected. Said profiled element, at the exit from the second rotating bush (4), exits straight, cleaned on its surface and slightly elongated. A traction assembly is then provided in order to be able to evacuate the material for subsequent work steps (for example cutting to size, rewinding into coils, drawing, et cetera).
In summary, the main body of the machine is constituted by the two assemblies with rotating bushes which produce a controlled spindle-like orbital rotation of the metallic rolled element, producing an alternating rotary stretching of the peripheral layers of the cross-section (the bar does not rotate about itself) and axial stretching, surface cleaning by virtue of the centrifugal and aerodynamic effect caused by spindle-like rotation.
The invention is of course not limited to the example of embodiment described above, starting from which it is possible to provide other forms and embodiments, and the details of execution can in any case vary without thereby abandoning the essence of the invention as stated and claimed hereinafter.

Claims

A method and an apparatus for dynamic straightening and surface cleaning for steel wire rods and/or bars, characterized in that the process for treating the cold- and/or hot-rolled metallic profiled elements, for surface cleaning, for slight stretching and for straightening, occurs by means of the automated cooperation and coordination of two particular orbiting rotating bushes which are crossed by the advancing profiled element; and orbital spindle-like rotation (avoiding rotation about its own axis) of said metallic profiled element is performed between said bushes; wherein the advancing material is thus subjected to a spindle-like controlled orbital rotation (1.1) by means of the rotating bushes (3, 4) on a plane which is perpendicular to its advancement direction; wherein said material in said region is subjected simultaneously to bending and slight traction (because it is subjected to the centrifugal force generated by spindle-like rotation); wherein the slight bending, with consequent stretching of the external parts, the controlled elongation and the aerodynamic effect caused by rotation determine the separation in small flakes of the iron scale (iron oxide) and/or of the other impurities that are present on the outer surface of the material; wherein in order to prevent the diffusion of the dust of iron scale and/or impurities into the environment, the spindle-like rotation region is covered by means of an appropriately provided collection container; such that the profiled steel, produced by hot rolling or by another treatment, at the output of the second bush is straight, clean and slightly stretched if required.
An apparatus for dynamic straightening and surface cleaning for steel wire rods and/or bars in the form of profiled elements, characterized in that in comprises:
means passing an advancing profiled element to be processed through two orbiting rotating bushes; and

means holding the profiled element in the bushes, such that to avoid rotation of the profiled element about its own axis;
wherein at least one of the bushes is adapted to input the profiled element coaxially to the rotation axis of said bush, and output the profiled element with a slightest deflection, i. e., slightly eccentrically, such that to subject the profiled element to a spindle-like controlled orbital rotation by means of the rotating bushes on a plane which is perpendicular to its advancement direction of the profiled element.
The apparatus for dynamic straightening and surface cleaning for a bar and/or wire rod made of steel according to claims 1 or 2, characterized in that the two assemblies that supporting the orbiting rotating bushes (3, 4) are coaxial; wherein the metallic profiled element being subjected to an advancement movement is made to pass through said bushes; wherein in the first bush (3), the profiled element enters centrally, coaxially to the rotation axis of said bush, and exits with a slightest deflection, i. e., slightly eccentrically; whereas in the second rotating bush (4) the profiled element enters and exits in the opposite manner with respect to the first one.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that the two rotation speeds of the two rotating bushes (3, 4) are actuated, controlled and adjusted with respect to each other automatically and/or manually by virtue of appropriately provided devices.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that it can be provided by means of a single rotating bush, either only the input one or only the output one with respect to the spindle shape, while the other one is of the fixed type; the rotation axis of the rotating bush and the axis of the fixed bush being coaxial or at an angle.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that the rotation axes of both bushes are not coaxial but are offset and parallel or at an angle.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that in the rotating bushes (3, 4), the input hole and the output hole for crossing by the advancing metal profiled element are eccentric with respect to its rotation axis and the eccentricity can be variable and adjustable even automatically.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that the two rotating bush assemblies (3, 4), or at least one of them, are movable, i. e., have a mutually adjustable distance.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that it provides for the management, control, and automated adjustment of one or more of the following operating parameters: a) rotation speed of the input bush (3); b) rotation speed of the second bush (4); c) advancement speed of the profiled element in input to the first bush; d) advancement speed in output from the second bush; e) relative speed of the profiled element between the two bushes in order to determine the elongation or stretching of the material; f) diameter of the rotation spindle of the profiled element.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that multiple apparatuses can be used in series in order to process the same material several times; said apparatuses being suitable to turn, by orbiting, the rolled element in a spindle-like manner in mutually identical and/or opposite directions of rotation.
The dynamic straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that the processed material can be worked directly (for example to perform electro-welding, galvanizing, et cetera) and/or rewound into coils, and/or drawn with a die, and/or cold-rolled with suitable rolling assemblies, and/or collected in straight wire rods cut to size.
The straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that a same machine can be equipped with multiple successive rotating bushes with a fixed and/or adjustable spacing in order to make the profiled element perform multiple spindle-like rotations one after the other.
The straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that it provides, in input and in output with respect to the rotating bushes which form the spindle, traction elements (2, 5) or guides whose speeds are mutually controlled and adjusted by virtue of automatic and/or manual systems.
The straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that it has capstans upstream of the rotating bush (3) and downstream of the rotating bush (4).
The straightening and cleaning apparatus according to claims 3 and 12, characterized in that the respective actuations, the rotation speed of the individual bushes (3, 4), and the advancement speed of the input and output profiled element (2, 5) mutually cooperate with automatic and/or manual coordination, in order to determine the chosen mechanical characteristics and at the same time ensure the quality of the treated product.
The straightening and cleaning apparatus according to one or more of the preceding claims, characterized in that the spindle-like motion of the rolled element is achieved by virtue of systems with a rotating magnetic field and/or oscillating magnetic field and/or other equivalent rotating and/or orbiting systems.
A method and an apparatus for dynamic straightening and surface cleaning for wire rods and/or bars made of steel and/or other metallic materials provided according to one or more of the preceding claims and according to what is substantially described and illustrated for the specified purposes.
A method for dynamic straightening and surface cleaning for steel wire rods and/or bars in the form of profiled elements, characterized by the steps of:
passing an advancing profiled element to be processed through two orbiting rotating bushes;

holding the profiled element in the bushes, such that to avoid rotation of the profiled element about its own axis;

subjecting the profiled element to a spindle-like controlled orbital rotation by means of the rotating bushes on a plane which is perpendicular to its advancement direction of the profiled element, such as to generate a centrifugal force on the profiled element to bend and produce a slight traction on the same, wherein the slight bending, with consequent stretching of the external parts, the controlled elongation and the aerodynamic effect caused by rotation of the profiled element determine the separation in small flakes of the iron scale and/or of the other impurities that are present on the outer surface of the profiled element; and

straightening the profiled element at the output of the bush positioned in the downstream direction with respect to the direction of advancement of the profiled element.