FIELD OF THE INVENTION

The present invention concerns a drawing device, applicable to feed oblong metal products such as bars, round pieces or metal wire, to a working machine such as a stirrup-making machine, bending machine or shaping machine, or other similar or comparable machine. In particular, the drawing device according to the present invention is applied to machines that simultaneously work at least two bars, round pieces or wires at a time, effecting a substantially uniform, coordinated and simultaneous feed.

BACKGROUND OF THE INVENTION

Working machines are known, such as bending machines, which are fed with oblong metal products such as metal wire from a roll, round pieces of iron, metal wire or pre-sheared bars, to obtain reinforcement stirrups for the building trade.

Such machines are generally fed with two or more metal products at a time, in order to optimize the productivity of the machine.

Both metal products fed from a roll, and also those in pre-sheared bars, are generally obtained at the end of the hot rolling cycle and have a plurality of ribs on their surface, in order to improve during use their gripping conditions with the cement.

Since they are made by rolling, and also because of the ribs, the section of the metal products is not perfectly circular, thus giving them an oval section characterized by a larger axis in correspondence with the ribs, and a smaller axis, angularly staggered by about 90° from the larger axis, and smaller by some millimeters.

Known bending machines are generally provided upstream with a drawing device for feeding the metal products to its operating stations.

Known drawing devices, as shown for example in WO 2007/141237 and WO 2010/04361 1, generally consist of a plurality of opposite rolls with respect to the advance axis of the metal products, to determine their advance in one or both directions, toward or away from the machine.

More specifically, machines that are suitable to simultaneously process two or more metal products are provided with a drawing device having a plurality of rolls, for example four, two of which are motorized, while the other two are disposed respectively opposite the motorized rolls and exert upon them a contrasting action on the metal products.

The motorized rolls are provided on their peripheral surface with a plurality of circular throats, in an equal number to that of the metal products simultaneously fed by the machine. Solutions are also known in which instead of each roll with two or more throats, there are two distinct and independent rolls adjacent on the same axis, each suitable to act on a respective metal product.

For each motorized roll there is a respective opposite contrasting roll. The number of coaxial contrasting rolls is normally the same as the number of rolled products that each motorized roll is suitable to feed. On each of the contrasting rolls a circular throat is made. The contrasting rolls are mounted idle on respective shafts and are disposed adjacent to each other so that each of their circular throats is disposed facing a corresponding circular throat of the corresponding motorized roll.

Each of the contrasting rolls can be moved by a respective movement device from or toward the corresponding motorized roll so as to be adjusted according to the nominal diameter of the product being worked, and to determine upon it a desired and adjustable contrasting action.

Elastic elements may be associated with the known contrasting rolls, for example Belleville springs, to absorb vibrations or to compensate slight variations in the diameter of the metal products.

In known solutions, it is still problematic to guarantee that high production, that is, high speeds of advance of the products, can be obtained at the same time as synchrony in the advance of the two products.

Another disadvantage of known drawing devices is the high number of components and devices that are used to motorize and move each of the rolls. In fact, these components and devices, due to the high power they must supply, have a large bulk that very often is not compatible with the need to reduce space for assembling a drawing device on a machine.

Another disadvantage of known drawing devices is the different contrasting actions that each of the contrasting rolls exerts on the circular throats of the motorized rolls. This can cause, over time, different conditions of wear on the circular throats of both the motorized and idle rolls. Therefore, over time, there is a loss, or at least a variation, in the guide function that each circular throat is able to perform, for example with respect to the throat of the adjacent roll. Furthermore, in the case where only one of the circular throats of one of the motorized rolls has reached its condition of maximum wear, it is necessary to replace the entire motorized roll even if the other circular throats are still integral.

One purpose of the present invention is to obtain a drawing device that allows to obviate, simply and effectively, the shortcomings of the state of the art, allowing a simultaneous and coordinated feed of several metal products at a time.

It is also a purpose of the present invention to obtain a drawing device that allows to obtain stirrups or shaped products with the same and repetitive geometries and sizes.

Another purpose of the present invention is to obtain a drawing device that is simple to make and to manage and that also allows to feed independently only one of the two products without any loss of efficiency and productivity.

Another purpose of the present invention is to obtain a drawing device that allows to reduce the complexities of design and assembly of the different components that are used to move the rolls.

Another purpose of the present invention is to obtain a drawing device in which the working life of the motorized and contrasting rolls is optimized.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a drawing device according to the present invention is used to simultaneously feed at least two metal products such as bars, round pieces or wire toward a machine, such as for example a bending machine, stirrup-making machine or shaping machine, or other similar or comparable machine. According to one feature of the present invention, the drawing device comprises at least a first drawing unit suitable to move at least a first metal product on a first feed plane defining a first advance axis, and a second drawing unit, distinct from the first and disposed aligned, upstream or downstream of it, in order to move a second metal product on a second feed plane defining a second advance axis, substantially parallel to the first advance axis.

By distinct from the first we mean that the second drawing unit must be understood as a separate structure from the first, with its own support frame, its own advance members, adjustments etc.

The first and second drawing unit each comprise at least a pair of drawing rolls, at least one of which is motorized, to which is associated a corresponding pair of guide rolls of the second drawing unit or respectively of the first drawing unit. The pair of drawing rolls of the first drawing unit and the pair of guide rolls of the second drawing unit are disposed on the first feed plane and define the first advance axis, while the pair of guide rolls of the first drawing unit and the pair of drawing rolls of the second drawing unit are disposed on the second feed plane and define the second advance axis.

In this way the first drawing unit is provided both with at least a pair of drawing rolls suitable to move the first product and at least a pair of guide rolls, lying on the second feed plane to guide the movement of the second rolled product that is drawn by the second unit. In the same way, the second drawing unit is also provided with at least a pair of drawing rolls lying in this case on the second feed plane and suitable to move the second product, and with at least a pair of guide rolls lying on the first feed plane and guiding the movement of the first rolled product drawn by the second unit.

This configuration allows to simplify the management of the movement of the metal products and also the complexities of the plant. Furthermore, it allows to feed independently either two metal products simultaneously, or one and the other irrespective of whether it is the external product or the internal product, keeping the productivity and drawing efficiency unchanged.

Furthermore, this configuration allows to make the movement of the first metal product independent from that of the second metal product, to suitably adjust the advance of one of the two products with respect to the other, so that they are made to advance at the same speed. In fact, the advance of each rolled product is determined independently by the pairs of drawing rolls of each unit.

According to another feature, in both the first drawing unit and the second drawing unit the rolls of the pair of drawing rolls are each disposed coaxial to one of the rolls of the pair of guide rolls.

According to another feature, for each of the drawing units, the corresponding drawing rolls are solidly associated with respective rotation shafts and the guide rolls are associated idle on said rotation shafts.

This therefore allows to exploit a single rotation shaft both to support in an adjacent manner a drawing roll that acts on a first metal product, and a corresponding guide roll that acts on a second metal product.

To this purpose the drawing rolls can be provided with connection means, or same-shape coupling means, with the respective rotation shafts to allow a solid rotation thereof. The guide rolls, on the contrary, are associated with rolling members, such as for example bearings or bronzes, which allow the independent rotation thereof with respect to the shafts on which they are mounted.

According to another feature, at least one of the rotation shafts is associated with drive members provided to make a corresponding drawing roll rotate. The other roll in the pair can be idle, to exert only a contrasting action.

In some forms of embodiment, in order to increase the drawing power available on each of the drawing units, it is possible to provide that both the rotation shafts are associated with respective drive members.

According to a variant of the present invention, at least one of either the first drawing unit or the second drawing unit comprises at least two pairs of drawing rolls disposed aligned with each other along the advance axis in order to increase the power available for drawing the metal products. It is advantageous to provide that corresponding two pairs of guide rolls are associated with the two pairs of drawing rolls on the other advance axis.

The fact that the first drawing unit and the second drawing unit are mounted on independent support frames facilitates the independent movements of the rolls of each of the pairs which exert the contrast against the others.

According to another feature, in the free space between the first drawing unit and the second drawing unit at least one pair of tensioner rolls are disposed, suitable to keep the metal products under tension.

This solution allows to define, between the first and second drawing unit, a uniform drawing of the metal products, for example preventing blockages or the formation of loops.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic plan representation of a drawing device for metal products according to the present invention;

- fig. 2 is a schematic representation from above of fig. 1 ;

- fig. 3 is a section view of a first detail of fig. 1 ;

- fig. 4 is a section view of a second detail of fig. 1 ;

- fig. 5 is a schematic representation of a variant of fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DESCRIPTION OF SOME PREFERENTIAL FORMS OF EMBODIMENT

With reference to figs. 1 and 2, a drawing device according to the present invention is indicated in its entirety by the reference number 10, and is suitable to feed both simultaneously and independently at least two metal products, in this case a first bar 1 1 and a second bar 12, respectively on a first feed plane P, defining a first advance axis X, and on a second feed plane S, defining a second advance axis Y (figs. 2 - 4).

The drawing device 10 (figs. 1 and 2) comprises at least a first drawing unit 13 suitable to generate the forces to feed the first bar 1 1 and to guide the movement of the second bar 12, and a second drawing unit 14, disposed downstream of the first drawing unit 13 and suitable to generate the forces to feed the second bar 12 and to guide the movement of the first bar 1 1.

The first drawing unit 13 comprises a support structure 60a on which a first group of rolls 15 and a second group of rolls 16, identical to the first group of rolls 15, are mounted. To this purpose we shall now describe the conformation of the first group of rolls 15, it being obvious that the description also applies to the second group of rolls 16.

Both the first 15 and the second group of rolls 16 are provided with four rolls, that is, a first roll 21, a second roll 22, a third roll 23 and a fourth roll 24 (fig. 3).

The first roll 21 and the second roll 22 are mounted coaxial with respect to each other on a first rotation shaft 25, while the third roll 23 and the fourth roll 24 are mounted coaxial with respect to each other on a second rotation shaft 26 disposed adjacent to the first rotation shaft 25.

The first roll 21 and the third roll 23 are solidly associated with the respective first 25 and second rotation shaft 26 and are disposed substantially aligned with each other on the first feed plane P, and respectively on the first advance axis X.

The first roll 21 and the third roll 23 are solidly associated with the first rotation shaft 25 and the second rotation shaft 26 by means of suitable connection means, in this case threaded connection means 27.

In other forms of embodiment, the connection means can comprise same- shape coupling members such as tongues or keys, or more generally members that prevent the reciprocal rotation of rolls and shafts.

The second roll 22 and the fourth roll 24 are mounted idle respectively on the first 25 and second rotation shaft 26, and are disposed substantially aligned with respect to each other on the second feed plane S.

Both the second roll 22 and the fourth roll 24 are mounted on the first rotation shaft 25 and on the second rotation shaft 26 by means of sliding members 29, in this case bearings.

The first 21, the second 22 and the fourth roll 24 are provided, on their circumferential surface, with a circular throat 28 shaped so as to allow the first bar 1 1 and the second bar 12 to be at least partly housed.

The third roll 23 is provided with a substantially cylindrical circumferential surface.

The first rotation shaft 25 and the second rotation shaft 26 are mounted on a first support frame 36a and on a second support frame 37a of the support structure 60a and are made to rotate around respective bearings 31 by means of a first drive member 32 and respectively a second drive member 33. Between the first and second rotation shafts 25 and 26 and the drive members 32, 33 respective kinematic transmission members 35 are interposed in this case pairs of gears.

The first drive member 32 and the second drive member 33 are made to rotate in a coordinated manner to allow a uniform drawing of each bar 11, 12, both on their upper and lower surface on which the two rolls 1 1, 12 respectively act. This allows to prevent the formation of blockages.

The second support frame 37a is selectively movable from and toward the first support frame 36b by means of actuator members 39 solidly associated with a bearing structure, not shown in the drawings, on which the first support frame 36a and the second support frame 37a are mounted.

The movement of the second support frame 37a allows to move the third 23 and fourth roll 24 respectively toward the first 21 and the second roll 22 to determine an action of pressure against the first 11 and second bar 12.

The second drawing unit 14 (figs. 1 and 2) comprises a bearing structure 60b on which a third group of rolls 41 and a fourth group of rolls 42 disposed downstream are mounted, substantially identical to the third group of rolls 41.

Both the third 41 and the fourth group of rolls 42 (fig. 4) are each provided with four rolls, that is, a fifth roll 45, a sixth roll 46, a seventh roll 47 and an eighth roll 48.

The fifth 45 and the sixth roll 46 are mounted on a third rotation shaft 49, totally identical to the first rotation shaft 25 as described with reference to fig. 3, and the seventh 47 and eighth roll 48 are mounted on a fourth rotation shaft 50 totally identical to the second rotation shaft 26.

The third 49 and fourth rotation shaft 50 provide conformations, support and actuation modes identical to those of the first 25 and second rotation shaft 26, and will therefore not be described again, except for the manner in which the rolls 45, 46, 47 and 48 are mounted.

The fifth roll 45 and the sixth roll 46 are mounted coaxial with respect to each other on the third rotation shaft 49, while the seventh roll 47 and the eighth roll 48 are mounted coaxial with respect to each other on the fourth rotation shaft 50.

The fifth roll 45 and the seventh roll 47 are mounted idle respectively on the third 49 and fourth rotation shaft 50, and are disposed substantially aligned with respect to each other on the first feed plane P.

The sliding of the fifth roll 45 and the seventh roll 47 respectively on the third 49 and fourth rotation shaft 50 is achieved by means of sliding members 29 identical to those described above.

The sixth roll 46 and the eighth roll 48 are solidly associated with the respective third 49 and fourth rotation shaft 50 and are disposed substantially aligned with respect to each other on the second feed plane S.

In this case too, as described before, with reference to the second 22 and fourth roll 24, the sixth roll 46 and the eighth roll 48 are solidly associated with the third rotation shaft 49 and the fourth rotation shaft 50 by means of suitable connection means 27, such as threaded connection means, or same-shape coupling means such as keys or tongues.

The fifth 45, the sixth 46 and the seventh roll 47 are provided, on their circumferential surface, with a circular throat 28, shaped so as to allow the first bar 1 1 and the second bar 12 to be at least partly housed.

The eighth roll 48 is provided with a substantially cylindrical circumferential surface which exerts a contrasting action against the sixth roll 46.

The third rotation shaft 49 and the fourth rotation shaft 50 are mounted on a first support frame 36b and on a second support frame 37b of the bearing structure 60b, exactly as described for the first 36a and the second support frame 37a of the support structure 60a.

Between the first drawing unit 13 and the second drawing unit 14 (figs. 1 and 2) a pair of tensioner rolls 53 are interposed, to keep the bars 1 1, 12 under tension.

Furthermore, upstream of the first drawing unit 13 and downstream of the second drawing unit 14 a plurality of straightener rolls 55 are disposed, with the function of straightening the bars 1 1 and 12 that are fed to the bending machine.

Other conveyor rolls 56 are associated in this case to the first support frame 36 to guide the bars 11 and 12 along the determinate direction of advance.

The tensioner rolls 53, the straightener rolls 55 and the conveyor rolls 56 are mounted idle on respective rotation pins and are also provided with peripheral circular throats to suitably guide the first bar 11 and the second bar 12.

In some preferential forms of embodiment, it is possible to provide a plurality of tensioner rolls 53, straightener rolls 55 or conveyor rolls 56, disposed coaxial with respect to each other and at different heights and through each of which one of the bars 1 1, 12 is made to pass. Each roll 53, 55, 56, mounted idle, will therefore be independent of the others mounted coaxial to it, thus allowing to compensate possible uncoordinated movements of the first 1 1 and second bar 12.

According to a second form of embodiment (fig. 5), the drawing device is indicated in its entirety by the reference number 1 10 and is substantially identical to the drawing device 10 described with reference to figs. 1-4, except for the second drawing unit that is indicated in its entirety by the reference number 1 14. The second drawing unit 114, unlike as described above, comprises only a third group of rolls 141 totally identical to the third group of rolls 41 described with reference to fig. 3.

In this case the second drawing unit 1 14 is suitable to move the second bar 12 only with the third group of rolls 141, instead of with two or more groups of rolls disposed adjacent to each other.

This form of embodiment is advantageous when it is necessary to draw a second bar 12 having a smaller diameter than that of the first bar 1 1, and therefore a lower movement power is required.

With reference to figs. 1 - 4, we shall now describe the functioning of the drawing device 10 according to the present invention.

The first 1 1 and the second bar 12 are fed forward respectively on the two feed planes P and S, making them pass through the straightener rolls 55.

Subsequently, both the bars 11, 12 are inserted through the first drawing unit 13 and through the second drawing unit 14.

The first roll 21 and the third roll 23, of both the first group of rolls 15 and the second group of rolls 16, are suitable to draw the first bar 11 also by a contrasting action that is exerted by the third rolls 23 against the first rolls 21 by translating the second support frame 37 against the first frame 36.

On the contrary, the second roll 22 and the fourth roll 24, of both the first group 15 and the second group of rolls 16, define between them a gap that allows the guided passage of the second bar 12.

In the second drawing unit 14 instead, the fifth rolls 45 and the seventh rolls 47, of both the third 41 and the fourth group of rolls 42, define between them a gap that allows the guided passage of the first bar 11.

The sixth rolls 46 and the eighth rolls 48 of both the third 41 and fourth group of rolls 42 are suitable to feed the second bar 12 by means of a reciprocal contrasting action.

It is clear that modifications and/ or additions of parts may be made to the drawing device 10, 110 for metal products as described heretofore, without departing from the field and scope of the present invention.

For example, in the first drawing unit 13 it is possible to provide that only the first rotation shafts 25 of the first 15 and second group of rolls 16 are made to rotate while the second rotation shafts 26 are rotatable idly around their own axes of rotation.

In this case therefore, the advance of the first bar is given only by the first rolls 21, while the third rolls 23 exert only a contrasting action on the first bar 1 1.

In the same way, in the second drawing unit 14 too, it is possible to provide that only the third rotation shafts 49 of the third 41 and fourth group of rolls 42 are made to rotate, while the fourth rotation shafts 50 are rotatable idly around their own axes of rotation.