Patent Description:
In particular, the drawing unit according to the present invention is applied, preferably but not restrictively, to machines that simultaneously work at least two bars, round pieces or metal wires at a time, carrying out a substantially uniform, coordinated and simultaneous feed.

Work machines are known, which are fed with oblong metal products, such as roll wires, round pieces, or pre-cut bars, to create, by way of example but not restrictively, reinforcement brackets for the building trade.

These machines can be bending/shaping machines, also called stirrup-making machines, and are generally fed with two or more metal products at a time, in order to optimize their productivity.

It is also known that a drawing unit is positioned upstream of the work machines in order to feed the metal products to be worked.

The drawing units known in the state of the art consist of a plurality of rollers, opposite each other with respect to the axis of feed of the metal products, in order to draw them. Normally one or more rollers of these rollers are motorized, while the others can be disposed in a position opposite to the metal products, acting as contrast rollers.

In some cases, a pair of contrast rollers, facing each other and not constrained to each other, can be positioned opposite one motorized roller, where each of them exerts a certain pressure on a metal product in the direction of the motorized roller.

This contrasting action is intended to ensure sufficient friction, between the metal product and the motorized roller, to obtain a uniform drawing action.

One disadvantage of known drawing units is that in some cases the compression action of the contrast rollers may fail, causing problems of slippage of the metal product or products being worked, thus generating waste or other inefficiencies. For example, in the case where two metal products are drawn, it may happen that one of them interferes with both the contrast rollers opposite to one of the motorized rollers, thus limiting the friction necessary for the coordinated drawing of both metal products.

It should be noted that this problem is particularly frequent since the metal products are generally obtained at the end of a hot rolling cycle and have a plurality of ribs on the outside. Since the metal products are made by rolling, together with the presence of the ribs, this makes the section of the metal products not perfectly circular, giving them an oval section characterized by a bigger axis, in correspondence with the ribs, and a smaller axis angularly offset by about <NUM>° from the bigger axis, and reduced by a few millimeters. The disposition of the metal products during drawing can therefore accentuate this interference. For example, a first metal product disposed with the bigger axis oriented perpendicular to the axis of feed and the axes of rotation of the rollers can interfere with both the contrast rollers, limiting the pressure applied to a second metal product, for example oriented offset by about <NUM>° with respect to the first.

Another disadvantage is that known drawing units do not always guarantee the correct positioning of the metal product with respect to the contrast roller and/or the motorized roller. In particular, in some cases the metal product can position itself near the lateral edge of the contrast roller and/or the motorized roller. This can cause considerable bending of the contrast roller and/or the motorized roller, promoting the slippage of the metal product. This problem is particularly frequent in the case of rollers with a flat lateral profile.

For this type of rollers, the optimal alignment is that which provides the metal product in the center of the lateral profile of the contrast roller.

The disadvantage just described limits the dimensional range of the metal products that can be drawn by the drawing unit, in practice reducing the flexibility of use thereof.

Document <CIT> is also known, which describes a drawing device for metal bars comprising a group of first rollers and a group of second rollers, in which each first roller is individually opposite to a corresponding second roller. The group of first rollers and the group of second rollers are mobile in diverging directions to regulate the passage channel that is created between a first roller and a second roller that are opposite each other.

Document <CIT> is also known, which describes an apparatus for feeding wire for arc welding machines.

Document <CIT> also shows an apparatus and a method for feeding a wire to a working machine, and forms the basis for the preamble of claims <NUM> and <NUM>.

There is therefore a need to perfect a drawing unit for metal products and the corresponding drawing method which can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide such a drawing unit which can limit the slippage of the metal products that it has to draw.

Another purpose of the present invention is to provide a drawing unit able to guarantee adequate pressure on the metal products, even when their diameter varies.

Another purpose is to provide a drawing unit which allows correct positioning of the metal products with respect to the motorized rollers and the contrast rollers.

In accordance with the above purposes, a unit for drawing metal products according to claim <NUM> is described which overcomes the limits of the state of the art and eliminates the defects present therein.

The drawing unit comprises at least one motorized roller configured to move at least one metal product along an axis of feed, and at least two contrast rollers configured to rotate idly about respective axes of rotation and disposed opposite the at least one motorized roller.

According to one aspect of the invention, the at least one motorized roller and the contrast rollers are selectively mobile, with respect to each other, along an axis of transverse movement substantially parallel to the axes of rotation of the contrast rollers.

According to another aspect of the present invention, the at least two contrast rollers are substantially facing each other and substantially coaxial.

According to the present invention, the at least two contrast rollers are opposite the same motorized roller.

In preferred embodiments, the at least two contrast rollers are selectively mobile with respect to the at least one motorized roller along the axis of transverse movement.

Advantageously, this solution allows to adjust the reciprocal position between the contrast rollers and the at least one motorized roller, in the transverse direction. This adjustment can be carried out, for example, as a function of the nominal diameter of the metal products to be worked, in such a way as to achieve the correct alignment between the metal product and the respective contrast roller in every situation. This allows to prevent a same metal product from interfering with both the contrast rollers which form a pair opposite the at least one motorized roller.

In addition, the contrast rollers can be able to be selectively moved toward the at least one motorized roller along an axis of movement that is orthogonal to the axis of feed and to the axis of transverse movement.

The present invention also concerns a method to draw metal products according to claim <NUM>.

According to one aspect of the invention, in the drawing step as above at least two metal products are drawn simultaneously, and a first contrast roller of the at least two contrast rollers acts only on a first metal product and a second contrast roller of the at least two contrast rollers acts only on a second metal product different from the first metal product as above.

In some embodiments of the method, the adjustment step provides to move the contrast rollers with respect to the at least one motorized roller along the axis of transverse movement.

Preferred embodiments provide that the step of adjusting the reciprocal position between the contrast rollers and the at least one motorized roller along the axis of transverse movement occurs as a function of the nominal diameter of the metal products to be worked.

It is understood that elements and characteristics of one embodiment can conveniently be combined or incorporated into other embodiments without departing from the scope of the appended claims.

With reference to <FIG>, the number <NUM> indicates a drawing unit configured to feed a machine (not shown) for working oblong metal products P1, P2 such as bars, round pieces or roll wires having a diameter that can even reach a few tens of millimeters. In particular, the drawing unit <NUM> can be disposed upstream of the work machine and downstream of a feeding unit (also not shown) configured to supply, at entry, the metal products P1, P2 to the drawing unit <NUM>.

In some cases, the work machine can be a bracket bending machine preferentially used to produce reinforcement brackets for the building trade.

The drawing unit <NUM> can comprise a base <NUM> with which one or more motorized rollers <NUM>, <NUM> can be operatively associated, the motorized rollers <NUM>, <NUM> being made to rotate about respective axes of rotation M1, M2 by means of drive members of the known type.

During use, on the motorized rollers <NUM>, <NUM> there can be disposed and supported the metal products P1, P2 to be drawn along an axis of feed X, which is tangential with respect to the motorized rollers <NUM>, <NUM>.

In this specific case, the drawing unit <NUM> can comprise two motorized rollers <NUM>, <NUM> disposed in succession, adjacent along the axis of feed X and having the respective axes of rotation M1, M2 parallel.

The two motorized rollers <NUM>, <NUM> are configured to rotate, during use, in a corresponding sense.

The drawing unit <NUM> can also comprise one or more contrast rollers <NUM>, <NUM>, <NUM>, <NUM> opposite the motorized rollers <NUM>, <NUM> with respect to the axis of feed X.

The one or more contrast rollers <NUM>, <NUM> and <NUM>, <NUM> are configured to rotate, during use, in a sense that does not correspond to the motorized rollers <NUM>, <NUM>.

The contrast rollers <NUM>, <NUM>, <NUM>, <NUM> can be hinged to the drawing unit <NUM> in an idle manner, in order to rotate freely about respective axes of rotation F1, F2, F3, F4.

The contrast rollers <NUM>, <NUM>, <NUM>, <NUM> are configured to apply a pressure on the metal products P1, P2 in the direction of the motorized rollers <NUM>, <NUM> in order to guarantee the correct friction between the motorized roller <NUM>, <NUM> and the metal product P1, P2, required to draw the latter.

In preferred embodiments, both the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> as well as the motorized rollers <NUM>, <NUM> have a lateral profile of contact with the metal products P1, P2 which is substantially smooth. In some cases, the lateral profile of the motorized rollers <NUM>, <NUM> can have gripping zones <NUM> configured to increase the friction with the metal products P1, P2, see <FIG>.

The contrast rollers <NUM>, <NUM>, <NUM>, <NUM> can be associated with a first support <NUM> of the drawing unit <NUM>, mobile in the direction of the motorized rollers <NUM>, <NUM> along a first axis of movement A orthogonal with respect to the axes of rotation F1, F2, F3, F4 of the contrast rollers <NUM>, <NUM>, <NUM>, <NUM>.

The first support <NUM> can be connected, by means of a sliding slider, to a second support <NUM> of the drawing unit <NUM>, operatively associated with the base <NUM>, and it can be moved along the slider by means of movement means of the known type.

In some embodiments, to one or more motorized rollers <NUM>, <NUM> there can be opposed at least one pair <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM> substantially facing each other, unconstrained from each other and independent of each other.

In particular, to each motorized roller <NUM>, <NUM> there can be opposed, with respect to the axis of feed X, a respective pair <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM>. Each pair <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM> comprises two contrast rollers <NUM>, <NUM> and <NUM>, <NUM> substantially facing each other, substantially coaxial, unconstrained from each other and independent of each other. In particular, two contrast rollers <NUM>, <NUM> and <NUM>, <NUM> of the same pair <NUM>, <NUM> are disposed in succession in a direction substantially parallel to their axes of rotation F1, F2 and F3, F4. Furthermore, by substantially facing each other and substantially coaxial we mean that between the axes of rotation F1, F2, and F3, F4 of the contrast rollers <NUM>, <NUM> and <NUM>, <NUM> of the same pair <NUM>, <NUM> a play is allowed which can be even of a few centimeters.

In this specific case, the drawing unit <NUM> comprises two pairs <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM>, each pair being opposite a respective motorized roller <NUM>, <NUM>. This configuration is particularly suitable in the event the work machine downstream has to operate on two metal products P1, P2 at a time.

The two pairs <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM> are disposed adjacent to each other in a direction parallel to the axis of feed X.

According to some embodiments, with reference to <FIG>, two homologous contrast rollers <NUM>, <NUM> and <NUM>, <NUM> of different pairs <NUM>, <NUM> can be hinged to a single contrast support <NUM>, <NUM> which is operatively associated with the first support <NUM>. In this specific case, the drawing unit <NUM> can comprise two contrast supports <NUM>, <NUM> to which respectively two contrast rollers <NUM>, <NUM> and <NUM>, <NUM> are hinged, adjacent in succession along the axis of feed X. Furthermore, the two contrast supports <NUM>, <NUM> can be disposed substantially facing each other so as to form the pairs <NUM>, <NUM> of contrast rollers <NUM>, <NUM> and <NUM>, <NUM> between them.

In some embodiments, the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> can be selectively mobile with respect to the first support <NUM> in directions substantially parallel to the first axis of movement A. This movement can be independent for each contrast roller <NUM>, <NUM>, <NUM>, <NUM>.

In other embodiments, it is the contrast supports <NUM>, <NUM> that can be selectively moved with respect to the first support <NUM> in directions substantially parallel to the first axis of movement A. For example, the contrast rollers <NUM>, <NUM> and <NUM>, <NUM> which respectively form the pairs <NUM>, <NUM> can be moved in directions that are substantially parallel to the first axis of movement A and independently of each other.

This configuration allows to carry out a first movement that takes the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> close to each other by moving the first support <NUM>, and a second adjustment movement by independently moving each contrast roller <NUM>, <NUM>, <NUM>, <NUM> or each contrast support <NUM>, <NUM> with respect to the first support <NUM>. This configuration is particularly advantageous if two metal products P1, P2 are drawn. In fact, a respective contrast roller <NUM>, <NUM>, <NUM>, <NUM> of a pair <NUM>, <NUM> can be dedicated to each metal product P1, P2.

According to one aspect of the invention, the motorized rollers <NUM>, <NUM> and the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> can be selectively mobile with respect to each other along an axis of transverse movement T substantially parallel to the axes of rotation F1, F2, F3, F4 of the contrast rollers <NUM>, <NUM>, <NUM>, <NUM>.

Advantageously, in this way it is possible to adjust, along the axis of transverse movement T, the relative position between the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> and the motorized rollers <NUM>, <NUM>.

In particular, in this specific case, the second support <NUM>, with which the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> are operatively associated, can be selectively moved with respect to the base <NUM> along the axis of transverse movement T. More in particular, the second support <NUM> can be coupled to the base <NUM> by means of at least one sliding slider <NUM> and it can be selectively moved by means of movement means <NUM> of a known type. For example, the second support <NUM> can comprise a screw <NUM> connected to a motor, and a nut-thread element <NUM> configured to accommodate the screw <NUM> can be integrally connected to the base <NUM>. It is therefore clear that a translation of the second support <NUM> along the slider <NUM> corresponds to a rotation of the screw <NUM>. The sense of the rotation defines the sense of the translation. In some cases, the extent of the translation may depend on the nominal diameter Φ<NUM>, Φ<NUM>, Φ<NUM> of the metal products P1, P2.

Advantageously, this configuration allows to adjust, along the axis of transverse movement T, the relative position between the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> and the motorized rollers <NUM>, <NUM> in such a way as to always guarantee the optimal alignment between contrast rollers <NUM>, <NUM>, <NUM>, <NUM>, metal products P1, P2 and motorized rollers <NUM>, <NUM>. In this way, it is possible to prevent the interference between a metal product P1, P2 and both contrast rollers <NUM>, <NUM>, <NUM>, <NUM> of a pair <NUM>, <NUM>.

For example, referring to <FIG>, the metal products P1, P2 have a first nominal diameter Φ<NUM> and the contrast rollers <NUM>, <NUM> of the pair <NUM> are positioned along the axis of transverse movement T in such a way as to prevent one of the two metal products P1, P2 from interfering with both contrast rollers <NUM>, <NUM>. In this way, the correct alignment and drawing of the metal products P1, P2 is guaranteed. Subsequently, with reference to <FIG>, the type of metal products P1, P2 to be worked may be different, for example due to a format change, and may have a second diameter Φ<NUM>, larger than the first diameter Φ<NUM>. In this case, as shown, the drawing unit <NUM> of the present invention can move the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> along the axis of transverse movement T in such a way as to restore the correct alignment with the metal products P1, P2. In another condition of use, with reference to <FIG>, the drawing unit <NUM> can be fed with a metal product P1 that has a third diameter Φ<NUM> larger than the second diameter Φ<NUM>. In this case, the contrast rollers <NUM>, <NUM> can be moved once again along the axis of transverse movement T in order to align the contrast roller <NUM> with the metal product P1. It is therefore clear to see the advantages of the drawing unit <NUM> of the present invention, which allows the transverse alignment of the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> as a function of the diameter of the metal products P1, P2 that have to be drawn. This makes the drawing unit <NUM> very flexible to use.

In some embodiments, the drawing unit <NUM> can also comprise a transducer device <NUM> configured to monitor the translation, that is, the distance of the second support <NUM> with respect to the base <NUM>. In fact, the transducer device <NUM> can be configured to generate an electrical signal that is proportional to the distance between the second support <NUM> and the base <NUM>. This solution allows a better regulation of the reciprocal position of the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> with respect to the motorized rollers <NUM>, <NUM>. In other words, the functioning of the movement means <NUM> can be adjusted as a function of the signal generated by the transducer device <NUM>.

The present invention also concerns a method to draw metal products P1, P2 comprising a drawing step, in which oblong metal products P1, P2 are drawn, along an axis of feed X, by means of motorized rollers <NUM>, <NUM> to which there are opposed, with respect to the axis of feed X, contrast rollers <NUM>, <NUM>, <NUM>, <NUM>. The contrast rollers <NUM>, <NUM>, <NUM>, <NUM> are configured to rotate idly about respective axes of rotation F1, F2, F3, F4.

Preferably, in such drawing step at least two metal products P1, P2 are drawn at the same time and a first contrast roller <NUM> of a first pair <NUM> of contrast rollers <NUM>, <NUM> acts only on a first metal product P1, and a second contrast roller <NUM> of the first pair <NUM> acts only on a second metal product P2. Furthermore, a first contrast roller <NUM> of a second pair <NUM> of contrast rollers <NUM>, <NUM> acts only on the first metal product P1, and a second contrast roller <NUM> of the second pair <NUM> acts only on the second metal product P2.

According to one aspect, the method also comprises at least one adjustment step in which the reciprocal position between the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> and the motorized rollers <NUM>, <NUM> is adjusted along an axis of transverse movement T substantially parallel to the axes of rotation F1, F2, F3, F4 of the contrast rollers <NUM>, <NUM>, <NUM>, <NUM>.

In accordance with some embodiments, the adjustment step provides to move the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> with respect to the motorized rollers <NUM>, <NUM> along the axis of transverse movement T.

In preferred embodiments, the above adjustment of the reciprocal position between the motorized rollers <NUM>, <NUM> and the contrast rollers <NUM>, <NUM>, <NUM>, <NUM> occurs, on each occasion, as a function of the respective nominal diameters of the metal products P1, P2, as described previously by way of example.

Advantageously, in this way it is possible to guarantee, in all conditions, an adequate pressure on the metal products P1, P2, eliminating the problems of slippage that are typical of drawing units of the traditional type.

It is clear that modifications and/or additions of parts or steps may be made to the drawing unit <NUM> and to the method as described heretofore, without departing from the field and scope of the present invention as defined by the claims.

Claim 1:
Drawing unit (<NUM>) for moving at least one metal product (P1, P2) along an axis of feed (X), comprising at least two contrast rollers (<NUM>, <NUM>; <NUM>, <NUM>) configured to rotate about respective axes of rotation (F1, F2; F3, F4) and disposed opposite one and the same motorized roller (<NUM>, <NUM>), with respect to said axis of feed (X), characterized in that said at least two contrast rollers (<NUM>, <NUM>; <NUM>, <NUM>) are selectively mobile with respect to said one motorized roller (<NUM>, <NUM>) along an axis of transverse movement (T) substantially parallel to said axes of rotation (F1, F2; F3, F4).