DRAWING ASSEMBLY IN MACHINES FOR WORKING METAL PROFILES AND

CORRESPONDING METHOD

Technical Field

The present invention concerns a drawing assembly, which can be included in machines for working metal profiles, in particular iron rods for reinforced concrete.

Background Art

It has been known that profiled irons, used for example for making reinforcements for reinforced concrete, are generally produced starting from metal profiled consisting of metal rods in coils or bars. For this purpose, metal profiles are fed, one or more, to working machines which automatically perform the manufacturing thereof, transforming them in a series of pre-designed products.

In particular, machines for working metal profiles in coils generally comprise a drawing assembly suitable to perform the feeding of the same profiles to the working members of the machine, arranged along a pre-established feeding line. Moreover, along the feeding line, straightening members are provided suitable to correct the bend of the profiles, especially in case they come from coils. For example, according to a known type, the drawing assembly can be arranged in an intermediate position between a first group of straightening members, laying on a substantially horizontal plane, and a second group of straightening members, laying on a substantially vertical plane.

The drawing assembly is generally made by one or more couples of counter-rotating wheels, arranged in series. For example, the drawing assembly can be made by a series of drawing wheels suitably motorized and a series of freely rotatable or equally motorized contrast wheels, substantially arranged on a same longitudinal plane, suitable to shape between them a feeding path, not always linear, for the metal profiles feeding to the machine. The wheels of the drawing assembly can be flat or grooved, that is having an annular throat which is engaged in use by the feeding profile.

Machines for working at the same time more profiles are known as well, for example so called "double-line" machines which allow to work simultaneously a couple of iron rods, in which the drawing assembly must be able to feed to the machine a couple of profiles, arranged side by side along a feeding line. In the case of double-line machines, the wheels of the drawing assembly can be flat or have a double groove, engaged in use by the above mentioned couple of profiles.

In the considered field, technical faults are often complained. In particular, in case of machines provided for simultaneously working more than one metal profile, the final length of profiles can sometimes result different, even though they are simultaneously fed by the same drawing members.

As long as it is concerned, it is necessary to underline that, as it is known, fed metal rods have geometrical and size irregularities, far from the theoretical shape and size for which drawing assembly provided for their feeding are set. As a matter of facts, metal rods do not have a perfect constant or circular section, on the contrary they often have a flat or elliptical shape, having one or more longitudinal ribbings, which extend all along the length of the profile and, in particular if they are fed unfolding from a coil, they have their section twisted like a helix according to a longitudinal direction of the same rod (see figure 1 1 ). The presence of such faults, which can be more or less evident, is due to the production technology and to the unfolding from the coils.

[08] Because of the presence of such irregularities, each metal rods reaches the drawing assembly with a longitudinally variable transversal section. In particular, for a theoretical stationary observer, placed in the passage zone defined between the drawing wheels, the helicoidal twisting produces an effect of rotation of the section, which in its turn has further shape irregularities, when passing through the drawing wheels. Obviously the difference of sections of the two metal rods being worked cannot be equal or synchronized at all. As a consequence, also the pressure of the drawing assembly on each fed rod can vary, thus producing uncontrolled slidings which finally cause undesired differences in the feeding of the rods crossing the drawing assembly.

[09] Moreover it is necessary to remind that the drawing assembly of such machines can sometimes work with a sole rod, usually using the more internal annular groove of the drawing wheels. For this reason, this internal groove wears out more than the others and consequently it produces a different pressure between the two rods, thus increasing said undesired slidings. Furthermore rods are not smooth, but provided with an "improved adherence", thus having on the surface pronounced ribbings, which shape and arrangement depends on producer's choice.

[10] As a result, it is possible that metal rods simultaneously fed to the machine have a different feeding and then produce profiles of different length.

[1 1 ] The European patent no. EP0693335 A1 discloses a drawing assembly provided with a device which compensates the extension of at least two metal rods. Such compensating device comprises a couple of counter-rotating grooved rolls, one of which, at least, is mobile parallel to itself on the containment plane of the same rolls, while the other is tilting on said containment plane of the axes and subject to compensation means comprising screw means and spring elastic recall means . By differently inclining the tiltable roll, by means of the said screw means, it is possible to produce a different pressure upon the two rods placed in the grooves of the rolls, theoretically recovering the different length of rods. However, such solution does not completely satisfy the exigency of correctly draw the couple of rods, but it produces a compensation based upon the difference of average diameter which could outcome in case of setting by hand. Such setting must anyway be performed by hand by the worker, suitably adjusting the screw means of a pre-established amount substantially on the base of the experience and of the ability of the worker.

Therefore the solutions proposed so far do not allow to completely solve the above mentioned problems, being complex and inadequate for the practical exigencies.

Disclosure

The task of the present invention is that of solving the aforementioned problems, devising a drawing unit which allows to feed in an optimal way more than one metal rod to a machine for working such metal profiles, in particular assuring the correct distribution of the load on the drawing wheels in order to obtain the identical length of each profile fed to the machine.

Within such task, it is a further scope of the present invention that of providing a drawing assembly which is able to continuously adapt to different rod sections which, time after time, reach the same drawing assembly.

Another scope of the invention is that of providing a drawing assembly having a simple conception, a surely reliable structure, a versatile use as well as relative economic costs. The cited scopes are attained, according to the present invention, by the drawing assembly according to claim 1 .

The drawing assembly, according to the invention, comprises at least a first wheel and a second wheel opposite and counter-rotating in a way as to define peripherally between them a feed path for a couple of profiles to be drawn, a motor member for driving at least one wheel of said first and said second wheel, a first support framework for the first wheel and a second support framework for said second wheel. An actuation device is provided for alternatively driving the first wheel and the second wheel between a spaced opening position and an approached tightening position, wherein the first and the second wheel are pushed one towards the other for tightening the couple of feeding profiles, with a resulting tightening force suitable to the feeding of the same profiles. The first support framework for the first wheel and the said second support framework for the second wheel are mounted tiltable to one another about a tilting axis parallel to the axes of the profiles arranged on the feed path. Such tilting axis is arranged in the passage zone of the feeding profiles, for allowing the relative tilting of the first wheel and of the second wheel with respect to such tilting axis, of width and direction so as to spontaneously compensate different variations of section for the couple of feeding profiles. Further to such spontaneous adjustment the resulting tightening force is kept equally distributed on both profiles, so as to assure that the feeding of the couple of profiles is equally balanced, that is, aligned.

In other words, further to such relative tilting capability of the drawing wheels, the same tightening or approaching force produced between the first and the second wheel forces the same wheels to be supported on both the approached profiles: the free relative tilting of the wheels produces the spontaneous orientation of the same wheels, so as to equally distribute the tightening stress on the contact zones of both the feeding profiles. This continuously occurs during the drawing, thus producing the continuous relative tilting of the couple of drawing wheels, for adapting to the different sections which arrive step by step in the passage zone for the profiles, without requiring a tracer, or pursuer member, or the operator intervention.

It is to be noted that the relative tilting capability of the first framework with respect to the second framework around the passage area of the feeding profiles allows the spontaneous adjustment of the inclination with no external intervention.

In practice, the particular position of the above mentioned tilting axis and of the direction in which the force resulting by the applied forces acts, serve as sensor for the survey of the section of both the feeding profiles, and as actuation member for the activation of the tilting suitable to constantly maintain the tightening on both feeding profiles and consequently for keeping the load equally distributed easing the construction and the quickness of the reaction when the shape of the profiles varies, always without requesting the external intervention of the operator.

Therefore, it is the same actuation device which drives the reciprocal approaching between the first drawing wheel and the second drawing wheel, that drives as well the spontaneous adjustment of the relative inclination of the two drawing wheels to the sections of the feeding profiles so as to produce the same pressure on both the feeding profiles.

Moreover it is important to underline that according to the invention the arrangement of the above mentioned tilting axis in the passage zone of the drawn profiles allows to reciprocally incline the drawing wheels without substantially modify the approaching of the wheels to the profiles and consequently the resulting tightening force, but, on the contrary, actively working for maintaining the same resultant tightening force constant and balanced on the drawn profiles.

According to the invention it is possible to create the tilting connection between the first framework and the second support framework of the drawing wheels through a kinematic chain equal or equivalent to a hinge pivoted at the cited tilting or hinge axis.

Such hinge preferably comprises a first coupling portion shaped by the first framework and a second coupling portion shaped by the second framework. The first coupling portion and the second coupling portion are then associated rotatable about the cited hinge axis, shaping each a tubular passage arranged around the hinge axis, for allowing the easy passage of the drawn profiles along the feeding path.

In practice the cited hinge is preferably tubular or "hollow" for enabling the arrangement of the tilting axis of the support frameworks of the drawing wheels where the cited adjustment action through tilting is better performed, without hindering the feeding of the profiles, thus creating a "tunnel" effect.

According to a particular embodiment the first framework is fixed while the second is pivoted mobile about the first framework around the cited tilting axis.

Moreover it is possible to provide a counter-weight member suitably applied at least to the second mobile framework and linked through connection means, preferably of flexible type, to a counter-means anchored to a fixed portion of the apparatus in which the assembly is mounted, in order to compensate not only the weight of the members assembled overhang with respect to the rotation centre but also possible further unbalancing actions.

According to a preferred embodiment, the cited tilting axis is arranged in a centred position between the above mentioned couple of profiles drawn in the feeding path.

As an alternative for the hinge it is possible to provide that the tilting connection between the first and the second framework is made through a plurality of articulations arranged externally to the passage zone of the profiles inserted in the feeding path. In such case the articulations are able to define a respective centre of instantaneous rotation virtually centred between the same profiles in the passage zone of the profiles, working in a completely corresponding manner according to the invention.

It is further possible to provide that the drawing assembly comprises blocking means of the relative tilting of said first framework and of said second framework, for blocking the cited spontaneous compensation tilting and allowing in such way the passage of a single profile in the feeding path.

According to a particular embodiment it is possible to provide a couple of first wheels and a couple of opposed second wheels functioning as previously described. In such case is then possible to provide preferably that the couple of second wheels is tilting with respect to the couple of first wheels, being each wheel of said couple of second wheels tiltable in an autonomous manner on a respective second framework.

The invention concerns as well a drawing method for a couple of profiles through a drawing assembly which comprises at least a first support framework for a first drawing wheel and a second support framework for an opposed and counter-rotating second drawing wheel, wherein the cited frameworks are tiltable to one another with respect to a tilting axis parallel to the feeding direction of the profiles, arranged in the passage zone of the feeding profiles. According to the invention the method provides to produce the drawing of the couple of profiles keeping a resultant tightening force which, in a manner corresponding to the drawing assembly described and claimed, is suitable to produce the spontaneous and reciprocal tilting of the first framework with respect to the second framework, of a width so as to compensate differentiated variation of section of the couple of profiles and keeping the above mentioned resultant tightening force equally distributed on the couple of feeding profiles.

Description of Drawings

Details of the invention shall be more apparent from the detailed description of a preferred embodiment of the drawing assembly according to the invention, illustrated for indicative purposes in the attached drawings, wherein:

figure 1 shows a perspective view of the drawing assembly object of the invention;

figures 2 and 3 respectively show a lateral view of a portion of the drawing unit according to different working conditions;

figure 4 shows a lateral view of the same drawing unit;

figures 5a and 5b respectively show a theoretical section and an actual section of a metal profile suitable to be fed to the drawing unit object of the invention;

figures from 6 to 10 respectively show lateral schematic views of the drawing unit, according to different working conditions and embodiments;

figures from 1 1 to 15 are respectively a lateral view, a section view, according to the trace planes XII, XIII, and XIV in figure 1 1 , and a perspective view of a rod in the actual configuration.

Best Mode

With particular reference to such figures, the drawing assembly provided for machines for working metal profiles 2 is indicated in its entirety with 1 .

The drawing assembly 1 comprises one or more drawing wheels 1 1 , 12, at least one of which is motorized, arranged in couples, so that each couple of wheels is cooperating for peripherally shaping a feeding path for the metal profiles 2 to be fed. More precisely, that drawing assembly 1 comprises a series of first drawing wheels 1 1 having preferably fixed axis, arranged for example at the lower side of the feeding path for the profiles 2, and a corresponding series of counter-rotating second wheels 12, mobile on their laying plane, opposite to the first wheels 1 1 with respect to the above mentioned longitudinal feeding path, thus for example at the upper side. In the illustrated case, the drawing assembly 1 comprises two couples of wheels 1 1 , 12, each comprising a first wheel 1 1 and a second wheel 12, but it is possible to provide a different number of drawing wheels, according to the specific working requirements.

The wheels 1 1 , 12 preferably comprise a respective annular groove 13 for housing and tightening the feeding metal profiles 2.

In order to allow the feeding of a couple of profiles, the wheels 1 1 , 12 of the drawing assembly 1 thus comprise a couple of grooves 13 placed side by side. In substance, between the first drawing wheels 1 1 and the second contrast counter-rotating wheels 12 a couple of metal profiles 2, which are arranged side by side, is drawn in longitudinal direction. As an alternative it is possible as well that the cited grooves 13 are not provided, or to provide them alternatively on a wheel of each couple instead of on both.

The wheels 1 1 , 12 are suitably motorized for performing the feeding of the profiles 2, through the connection with a suitable motor member 14, 15 (see figure 4). As an alternative, it is possible to motorize the first wheels 1 1 only or the second wheels 12 only. Anyway it is possible to motorize only one wheel of each couple, the remaining wheels being freely carried rotatable according their rotation axis.

According to the invention the first wheels 1 1 are mounted of a first framework 3, preferably fixed, while the second wheels 12 are mounted mobile on a second framework 4 tiltable with respect to the first framework 3.

More precisely, the second wheels 12 are carried mobile by an actuation device 5, suitable to perform a sliding displacement of the same second wheels 12 between a spaced opening position, for example lifted, and an approached position, for example lowered, in which, when one or more profiles 2 are interposed between the same wheels, the first wheels 1 1 and the second wheels 12 are pushed one against the other in opposite direction towards the opposite first wheels 1 1 , performing the tightening of the interposed profiles for their drawing along the cited feeding path, through a resulting tightening force A.

The actuation device 5 preferably comprises a single actuation member 6 mounted, with for example substantially horizontal axis, between a couple of lever arms 7, in practice square shaped and pivoted, at relative pins 8, to the second mobile support framework 4 of the drawing assembly. The bell cranks 7 are articulated through connecting rods 9 for transmitting to the sliding support of the axis of the second wheels 12 the required pushing force through suitable counter-articulations. The activation in extension of the actuation member 6 causes the reciprocal spacing of the lever arms 7, so as to produce the simultaneous lifting of the second wheels 12 in the opening position of the drawing assembly 1 , which allows the insertion of the profiles 2 in the respective annular grooves 13. The opposite closing movement of the actuation member 6 obviously produces the simultaneous stroke of the same second wheels 12 in the tightening position, that is in the drawing position for the metal profiles 2.

According to the present invention, the second mobile framework 4 is pivoted to the first fixed framework 3 through a hinge, around a tilting or hinge axis parallel to the axes of the profiles 2, and preferably comprised between the planes containing the respective tightening forces acting on the same profiles 2 feeding on the drawing assembly 1 , in order to enable the spontaneous adjustment of the wheels 1 1 , 12 to the irregularities of the section of the feeding profiles 2. As previously described, indeed, the feeding profiles 2 can have an irregular actual shape 2' (see figures 5b, 12, 13, 14 and 15), characterized by ribbings 30 and grooves 31 , or by other irregularities coming out from the technology used for their production, such as for example the one of giving the section a flattered or oval shape. In particular, ribbings 30 are generally provided for easing the adherence of the profile with the surrounding concrete. Ribbings 30 can be arranged inclined along the longitudinal axis of the same profile 2. In this way the wheels 1 1 , 12 of the drawing assembly 1 receive transversal sections with continuously variable shapes. Instead, grooves 31 , which can be two or more, arranged on the perimetral rim of the section all along the length of the profile 2', are undesired irregularities, usually coming out from the technology used for their production.

Finally it is necessary to underline that further to the unwinding of the coil, the profile 2' is usually twisted with a substantially helicoidal shape wound around its same longitudinal axis, as illustrated for example in figure 15.

Therefore the geometry and the diameter of the real profile 2' section interposed between wheels 1 1 , 12 can continuously vary during the feeding through the drawing assembly 1 . In particular, because of the cited helicoidal shape, profiles 2' sections continuously rotate around their longitudinal axis during the feeding through the wheels 1 1 , 12.

Moreover, as previously indicated, the grooves 13 of the wheels 1 1 , 12 can be themselves worn out and geometrically different, for example because of a different use of the grooves 13.

According to the invention, in order to enable a correct tightening of the profiles 2' the first wheels 1 1 and the second wheels 12 can tilt to one another around the hinge axis of the hinge 20, so as to make a diverted arrangement with respect to the coplanar planes of the same wheels. In particular figure 7 shows a diverted arrangement of the wheels 1 1 , 12, suitable to compensate the diameter difference of the sections of the profiles 2 feeding through the wheels 1 1 , 12. In figure 8 is shown a diverted arrangement essentially similar, but suitable, in this case, to compensate the difference of thickness interposed between the wheels 1 12, 12, produced by different orientations of two feeding oval sections. In particular this circumstance does not occur in a determined step, on the contrary it requires a continuous and unpredictable adjustment of the arrangement of the wheels, which can produce correspondent tilting of range a of the same wheels 1 1 , 12 in both directions (see tilting angles, which range is generically indicated with symbols +a and -a in figures 2 and 3).

The hinge 20 thus serves for adjusting the reciprocal arrangement between the first wheels 1 1 and the opposed second wheels 12, according to the section variations and to the arrangement of the feeding profiles 2, 2'. The hinge 20 can be made of a first coupling portion 21 shaped by the first framework 3 and by a second coupling portion 22 shaped by the second framework 4. The first coupling portion 21 and the second rotatable coupling portion 22 are preferably associated rotatable through the interposition of suitable bearings, for simplicity not illustrated in figures.

[54] The first coupling portion 21 and the second coupling portion 22 shape each a tubular path 23, 24 arranged around the hinging axis, so extended that they allow the easy passage of the profiles 2, 2' drawn along the feeding path. Preferably the hinge axis of the hinge 20 is arranged in a substantially intermediate position on a plane containing the axes of the profiles feeding on the same containing plane, so as to allow as well spontaneous tilting +a, -a compensating the wheels 1 1 , 12 in both directions, for the efficient tightening of all interposed profiles 2, 2'.

[55] Substantially, the orientation between the first wheels 1 1 and the second wheels 12 of the drawing assembly 1 varies according to an inclination centred on the rotation axis of the rotatable coupling defined by the hinge 20. Such adjustment of the reciprocal inclination of the planes containing the wheels 1 1 , 12 is automatically produced as a reaction of the tightening action produced by the actuation member 6. Thanks to this continuous adjustment, the illustrated solution, in which the hinge 20 has its hinging axis arranged at the passage zone of the profiles 2, 2', that is with a tubular or "hollow" hinge, that is provided with the tubular passages 23, 24, is optimal. As an alternative, different solutions are possible in which kinematic chains of the articulated square type can be used for producing a tilting movement in both directions of the planes of the wheels 1 1 , 12, which are equivalent to the described hinge 20 from the functional point of view. In particular such kinematic chains can comprise a plurality of articulations arranged externally to the passage zone of the profiles 2, 2', anyway they must be able to define a respective centre of rotation substantially centred between the same profiles, thus being able to spontaneously compensate in both tilting directions the section irregularities of the feeding profiles.

[56] Finally the drawing assembly 1 can advantageously comprise a counter-weight 16, suitably applied to the first framework 3 and to the second framework 4, in order to compensate the forces produced by the weight of the overhang members constrained to the second mobile framework 4 in contrast with the automatic adjustment of the inclination of the wheels 1 1 , 12 to the profiles 2 feeding through the drawing assembly. The counterweight member 16 can as well compensate the weight of further working members which can be anchored to the working plane of the machine which, for ergonomic reasons, is usually arranged inclined with respect to a vertical plane. Therefore the contribution of such working members generally tends to generate a momentum with respect to the tilting axis of the hinge 20 or of the cited equivalent solutions, suitable to contrast the correct and spontaneous compensation of the section irregularities of the drawn profiles. In order to contrast such undesired forces the counter-weight member 16 can be connected through suitable flexible means 17, for example, wires, cables and counter- means 18, 19 with a fixed portion of the machine in which the drawing assembly 1 is used. The functioning of the drawing assembly is easy to understand through the preceding description.

In a first insertion step, the actuation device 5 is activated for driving the drawing assembly 1 in the open position, suitable for the insertion of the profiles 2 to be fed.

Subsequently the actuation device 5 is activated for tightening the profiles 2, 2' inserted in the respective grooves 13 between the first wheels 1 1 and the second wheels 12 (see figure 6). The produced tightening force causes the reciprocal approaching of the wheels 1 1 , 12 until tightening the interposed profiles 2, 2', driving the second wheel 12 in contact with the section of major thickness. Further to such dynamics, the same approaching force causes the relative tilting of the wheels 1 1 , 12 around the hinge axis corresponding to the hinge 20 or to equivalent solutions, until reaching the contact with the peripheral surface of the wheels 1 1 , 12 also on the other interposed section. Upon reaching such configuration, it is possible to estimate that the tightening force produced by the reciprocal approaching of the first wheels 1 1 and of the second wheels 12 is divided in substantially balanced way between the interposed profiles 2, 2'. In practice, the resulting approaching force A, which acts according to a direction passing through the centres of the fed profiles 2, 2', determines an instable balance, suitable to produce the relative rotation of the first wheels 1 1 and of the second wheels around the hinge axis when the shape of the section of the interposed profiles 2, 2' in the drawing assembly 1 is different and produces different and unbalanced drawing actions. Thus the device spontaneously tends to balance the support on both profiles 2, 2' for balancing the overall produced forces.

Subsequently the motor members 14, 15 are activated for performing the rotation of the wheels 1 1 , 12 and consequently producing the feeding of the inserted profiles 2.

During the feeding of the profiles 2, 2' tightened between the wheels 1 1 , 12 the transversal section of the same can vary, for example as shown in figures 7 and 8. In such cases the tightening performed by the actuation device 5 automatically determines the adjustment of the reciprocal inclination of the first wheels 1 1 and of the second wheels 12 to the different shapes of the sections which reach the drawing assembly. In other words, the resulting force A of the actions produced on the wheels 12 assures the constant support on the profiles 2, 2' independently from the possible sudden variation of the interposed thickness. The resulting force A is arranged preferably in a median plane among the vertical lines passing through the axes of the profiles 2, 2' (see figure 9), but in any case between them. As a consequence, the tightening is constantly assured for the undiffertiated feeding of the profiles 2, 2' interposed between the wheels 1 1 , 12. In particular the counter-weight member 16 can be advantageously used for easing and perfectly balancing the tightening between the two profiles 2, 2' (see figure 10).

Therefore, in use, the metal profiles 2, 2' to be fed to the machine proceed side by side along the feeding line shaped by the first wheels 1 1 and the second counter-rotating wheels 12, resulting perfectly and constantly tightened in equal manner and therefore drawn of the same quantity.

The length of the tract of profile fed to the machine in such way does not depend on possible wear occurrences of the grooved of the drawing wheels or possible irregularities of the shape of the same profile, mechanical hindering, or other reasons of differences in the drawing force. In particular it is possible to feed at the same time to the machine metal profiles of diameter not perfectly identical, even if they should be equal, assuring the correct length of each of them.

Moreover in practice the first and the second wheel or both can be indifferently tilting, as well as the one or the other can be the drawing one, therefore the tilting wheel can be idle, of simple contrast or drawing too.

The drawing assembly therefore reaches the aim of feeding in an independent way more than one metal profile to a machine for working such profiles, particularly making sure that the length of each profile fed to the machine is correct, when the machine works more than one metal profile at the same time.

The drawing assembly described for indicative purpose is susceptible of numerous modifications and variants according to the diverse exigencies.

In practice, the embodiment of the invention, the materials used, as well as the shape and dimensions, may vary depending on the requirements.

Should the technical characteristics mentioned in each claim be followed by reference signs, such reference signs were included strictly with the aim of enhancing the understanding the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.