The present invention concerns a machine for bending metal bars, such as for example round pieces for reinforcement, structural shapes, tubes or other profiles with any section shape.

In particular, the machine according to the present invention allows to bend both ends of the metal bar, with bending angles of 180° or more, and can be used both to bend a single bar at a time and two or more overlapping bars and shaped at the same time.

A machine for bending metal bars is known, comprising a first movement device to move the bars, or lead drawing device, a bending device and a second movement device to move the bars, or tail drawing device, disposed downstream of the bending device and suitable to move the bar forward/backward once this is not being gripped by the first movement device.

A shearing to size device, or shears, is interposed between the first movement device and the bending device to shear the bar to size.

In particular, when making a shaped profile having a desired shape, the first movement device feeds the bars toward the bending device along a direction of feed and on a determinate feed plane.

The bending device normally comprises a bending mandrel, with a substantial disc shape and provided, in proximity to its axis of rotation, with a contrast element of a substantially cylindrical shape and around which the bar is bent.

The mandrel also comprises, in proximity to its periphery, a bending pin, also substantially cylindrical, which, when the mandrel rotates in one direction or the other, bends the bar around the contrast pin.

One disadvantage of this machine is that, if the bent segment of the bar has a rather large extension, this interferes with the devices disposed nearby, upstream and/or downstream of the bending device, thus deforming the bent bar and often not allowing to obtain particular figures or shapes. Such devices are normally the shears, the first or the second movement device, contrast elements etc.

However the movement devices are also needed during the execution of the bends to maintain the bar gripped when it is bent, so that it does not slip.

To partly overcome this drawback, the devices disposed in proximity to the bending device have been provided with protection elements conformed as an inclined plane which, when the bar is bent, divert it to prevent it from jamming against them.

This solution, although it prevents problems of interference with the devices, generates structural shapes which are not coplanar and therefore of a low quality.

To overcome these disadvantages it is also known to translate the bending device and the movement device which feeds the bar to the bending device, with respect to the feeding plane in order to prevent the bar from interfering with other devices.

In this case the disadvantage of interference remains, however, for bars which are bent at an obtuse angle with respect to each other and/or which have very long extensions of the bending sides.

In particular, for these operations, it is provided to feed the bar completely toward the second movement device and, with the latter, feed the bar to the bending device, making the bar retreat in an inverse direction with respect to the direction of the first feed.

Subsequently, the rolls of the second movement device are kept gripping on the bar and the bending is carried out. When the bending angle has very high values, near to 180°, the bent segment interferes with the second movement device which keeps the bar gripping, and in particular at least with one of the pairs of rolls disposed on the side where the bending is carried out, not allowing the execution of substantially U-shaped bends, or the execution of shaped profiles which are adequately coplanar.

Document WO 2005/061144 A1 describes a bending device for metal bars having a first drawing unit upstream of the bending device and a second drawing unit downstream of the bending device, wherein contrast grippers are interposed between each drawing unit and the bending device. Both the drawing units and the contrast grippers can assume a first operating position above the work plane and a second retractable position of non-interference below the work plane. However, WO'144 does not provide that only a part of the contrast grippers, or only a part of the movement device, can move from one or the other of the positions so as to allow the execution of the bends even at 180° and guaranteeing that the bar being worked is supported.

One purpose of the present invention is to achieve a machine for bending bars which allows to obtain a final product shaped substantially flat whatever its shape or size, starting from bars subjected to bending.

Another purpose of the present invention is to achieve a bending machine which is simple to make and limited in size.

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.

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

In accordance with the above purposes, a machine for bending metal bars, such as round pieces for reinforcement or suchlike, comprises a first movement device and a second movement device suitable to move, along a work plane, at least one bar toward a bending device interposed between the first and the second movement device.

The bending device comprises a rotating mandrel, provided peripherally with a bending pin and centrally with a contrast member around which a first segment of the bar is suitable to be bent on each occasion so as to obtain the shaped profile having the final desired shape.

The second movement device can be selectively positioned in a first condition, protruding with respect to the work plane, in which it is suitable to move the bar toward the bending device and to hold at least momentarily a second segment of the bar during bending, and in a second condition in which it is disposed completely under the work plane and not interfering with the movements of the bar.

According to a first feature of the invention, the machine also comprises at least a mobile pin disposed downstream of the bending device and suitable to selectively assume at least a retracted non-operating position under the work plane and not interfering with the movements of the bar, and an operating position protruding with respect to the work plane in which it is suitable to support and contrast the movement of the second segment of the bar, that is, the one not being bent, when the second movement device is in the second condition, that is, completely retracted under the work plane, and when the first segment of the bar, that is, the one being bent, is bent or at least its bending is completed.

The second protruding operating position of the pin is in fact temporally and functionally coordinated to the second retracted condition under the work plane of the second movement device.

The presence of the mobile pin which is selectively activated, located on the opposite side to that of the first segment of the bar which is being bent, allows the second movement device to disappear below the work plane, thus rendering it non-interfering with the execution and/or the completion of the bending of the bar; this allows to execute bends with bending angles having values of about 180°, that is, substantially U-shaped bars and with substantially coplanar bending sides. Moreover, since it supports the second segment of bar which is not being bent, the mobile pin prevents the bar from moving or rotating around the contrast member, altering the position, along the longitudinal extension, in which the bar is bent.

According to one form of embodiment, the mobile pin is disposed between the bending device and the second movement device, advantageously in a position near that of the bending device, in order to reduce the effects of localized deformation due to the action of contrast which is achieved by the bending pin during bending.

According to another feature, actuation means are associated to the mobile pin and are suitable to selectively move it into the operating and non-operating condition on the command of a central control unit.

According to one form of embodiment, the mobile pin is associated to the second movement device, and its movement occurs independently from the movement of the second movement device with respect to the work plane of the machine.

In a preferential form of embodiment, it is possible to provide that, between the bending device and the second movement device, there are clamping means interposed, which can be selectively positioned between an operating position and a position in which they are retracted under the plane. In the operating condition they are suitable to constrain the sliding of the bar along its longitudinal extension, and therefore allow bends to be made in positions which are very precise along the extension of the bar.

According to another form of embodiment, alternative to or integrated with the previous one, the action to contrast and support the second segment of the bar, during the completion of bends of up to 180°, is carried out by one or more elements of the second movement device which, during use, are disposed on the side where the bending is carried out.

In another form of embodiment, the action to contrast and support the second segment of the bar can be carried out, or also carried out, by parts of the clamping means.

More in particular, the second movement device, and/or the clamping means if present, each comprise at least a first and a second element, opposite each other with respect to the axis of feed of the bar and between which the bar is made to advance, and the second segment of the bar is possibly held during bending.

From the first operating condition assumed by the second movement device and/or by the clamping means, the first element or elements are selectively movable, transverse to the work plane of the bars, in order to move them under the work plane and in a position of non-interference with the first segment of the bar which is bent, while the second element or elements remain external or protruding from the work plane in order to support and contrast the movement of the second segment of the bar.

By first and second element we also mean units composed of two or more elements opposite each other with respect to the axis of feed of the bar.

Therefore it is possible to provide that the contrasting action is carried out in cooperation both by parts of the second movement device and also by parts of the clamping means, or alternatively by only one of these, whereas the other, either the first or the second element, is taken completely under the work plane.

According to one feature of this form of embodiment, the first element comprises at least a first roll and the second element comprises at least a second roll, which are associated respectively with a first and a second frame. When set up, the first and the second frame are associated to respective first and second actuation means which allow the autonomous and reciprocally independent movement thereof with respect to the work plane.

The present invention also concerns a method for bending metal bars, such as round pieces for reinforcement or suchlike. In particular the method comprises a step of feeding a bar along a work plane and toward a bending device by means of a first movement device or a second movement device, disposed respectively one upstream and the other downstream of the bending device, and a step of bending the bar carried out by the bending device.

According to one feature of the method, when the first segment of the bar which is being bent begins to interfere with the second movement device, a mobile pin, disposed downstream of the bending device, is moved from its non-operating position, retracted under the work plane, into an operating position, protruding with respect to the work plane, to support and contrast the movement of the second segment of the bar in order to complete the bending of the first segment of the bar, and the second movement device is taken under the work plane and in a position of non-interference with the movements/bending of the bar.

If the action to support and contrast the bar is carried out by an element of the second movement device and/or possibly by the clamping means, instead of, or together with the mobile pin, when the first segment of the bar begins to interfere with the second movement device, the first element/elements located on the bending side is/are moved transverse to the work plane of the bars and with respect to the second element/elements, in order to take them into a position of non-interference with the first segment of the bar which is being bent, while the second element/elements supports/support and contrasts/contrast the movement of the second segment of the bar during the bending, or the completion of the bending, of the first segment of the bar.

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 view of a bending machine according to the present invention;
• - fig. 2 is a partial view in section of fig. 1;
• - fig. 3 is a partial view in section of a variant of fig. 2;
• - figs. 4 - 9 are schematic views of the machine in fig. 1 in different operating configurations;
• - fig. 10 shows a variant of a detail of fig. 2;
• - fig. 11 shows another variant of a detail of fig. 2.

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.

With reference to the attached drawings, a machine for bending metal bars B is denoted in its entirety by the reference number 10 and comprises a first movement device 11, or lead drawing device, to draw a bar B toward a bending device 12, a second movement device 13, or tail drawing device, substantially aligned with the first, and disposed downstream with respect to the bending device 12, and a shears 15 to shear to size the bar B fed by the first movement device 11 which is disposed downstream with respect to the latter.

The first movement device 11 (fig. 1), of a substantially known type, comprises motorized rolls 16 which receive the bar B from feed means, not shown in the drawings, which in turn pick up the bars, either from a bundle of bars or directly from a coil.

The first movement device 11 is suitable to make the bar B advance along a direction of feed D toward the bending device 12, and on a work plane P (fig. 2) for working the bars B.

The shears 15 (fig. 1) is suitable to shear the bar B to a desired predetermined length and is disposed substantially on a plane coinciding with the work plane P of the bars B.

The bending device 12 (figs. 1 and 2) comprises a rotating mandrel 20 conformed substantially as a disk and provided on its periphery, solid therewith, a bending pin 21, substantially cylindrical in shape, which extends orthogonal with respect to the rotating mandrel 20.

The bending device 12 also comprises a contrast pin 22, solidly associated with the rotating mandrel 20, in proximity to its center of rotation and around which the bar B is bent.

Motor members 23 are also associated with the rotating mandrel 20, in a known manner, and are suitable to rotate the latter around its axis, and first translation means 25, in this case an actuator suitable to translate the rotating mandrel 20 along its axis of rotation and with respect to the work plane P of the bar B, to take the bending device 12 to a first, second and third position, in which the latter is disposed respectively on the same plane, on a lower plane, or on an upper plane with respect to the work plane P of the bars B.

The rotating mandrel 20 is associated with a support plane 41 which is selectively movable by means of a linear actuator 42 which is suitable to move the rotating mandrel 20 to position the contrast pin 22 substantially tangent to the bar B that is fed. In the case shown in fig. 1 the contrast pin 22 is positioned under the bar B to execute bending, of both the leading and tail end, downward. In the same way (fig. 7), by positioning the contrast pin 22 above the bar B, it is possible to execute bending, of both the leading and tail end, upward.

The second movement device 13 in this case comprises a pair of motorized rolls 27, and a pair of contrast rolls 29 selectively translatable toward the pair of motorized rolls 27 by means of actuators 30 which act substantially in a transverse direction with respect to the direction of feed D.

Both the motorized rolls 27 and the contrast rolls 29 are mounted on respective supports associated with a protective and supporting casing 39.

The pair of motorized rolls 27is selectively rotatable, in a known manner, by means of motor means 31 to make the bar B advance or retreat from or toward the bending device 12.

The second movement device 13 is selectively translatable orthogonal to the work plane P by means of second translation means 32, to take respectively the rolls 27 and 29 completely under the work plane P, or to a position where the second device 13 does not interfere with the bar B which is being bent, as shown in fig. 2, or into a position substantially aligned with that of the work plane P of the bar B and where the rolls 27 and 29 are suitable to draw the bar from or toward the bending device 12, or into another, super-elevated position suitable to make the bar B available to the bending device 12 when the latter is in its third position, that is, super-elevated with respect to the work plane P.

In the form of embodiment shown in fig. 2, an element to support and contrast the bar B is associated with the second movement device 13; in this case, the element is a support pin 33 which is selectively moved by an actuator 35 to take it selectively to a protruding position with respect to the work plane P of the bar B, or to a retracted position where it does not interfere with the movements of the bar B.

In particular, the protruding position with respect to the work plane of the bar B is also obtained if the second movement device 13 is completely under the work plane P of the bar B.

More specifically, the function of the support pin 33, during the bending of the bar B, is to support and contrast the bar B.

In another form of embodiment (fig. 3), instead of being associated with the second movement device 13, and therefore being selectively moved with it, the support pin 33 and the corresponding actuator 35 are attached to a fixed part 40 of the machine, that is, a plane substantially coinciding with the work plane P of the bar B.

This solution allows to dispose the support pin 33 in a position very close to the bending device 12, allowing to obtain bent bars even with very limited end extensions. Furthermore, disposing the support pin 33 in a position very close to the bending device 12 reduces the bulging effect of the bar that occurs between the contrast pin 22 and support pin 33 during the bending action.

In both cases, the support pin 33 is disposed laterally to the direction of feed D of the bar B and in such a manner that it is also peripherally aligned with the motorized rolls 27.

Near the zone where the bar B enters the second movement device 12, clamping means 37 are disposed, in a known manner, which during the bending of the bar B are selectively activated to keep the bar B clamped and to prevent it from sliding, which would modify the position of the bend.

The work plane P of the bar B, that is, the work plane of the machine 10, is advantageously inclined to allow the bar, once it is bent and no longer supported, to be conveyed to a zone where the bent articles are discharged.

The machine 10 according to the present invention functions as follows.

The bar B is fed forward by the first feed device 11 toward the bending device 12 for a length equal to the overall extension of the bent bar to be obtained. In this position, both the bending device 12 and the second movement device 13 are disposed completely under the work plane of the bar B, so as to be disposed in a position that does not interfere with the advancing bar.

Subsequently, the bar B is sheared to size by the shears 15 (fig. 4) and both the bending device 12 and the second movement device 13 are raised by means of the respective first 25 and second translation means 32, to be disposed on a plane coinciding with the work plane P (fig. 5).

In this condition the bar B is interposed between the pair of motorized rolls 27 and the pair of contrast rolls 29, which in turn are translated by the actuators 30 against the motorized rolls 27, to keep the bar B clamped between them.

Subsequently, both the bending device 12 and the second movement device 13 are further translated vertically to be taken, in coordination, to a super-elevated position with respect to the work plane P of the bars B. In this condition, it is possible to bend even very long bars B, preventing problems of interference with the first movement device 11 or with the bending device 12.

In this condition, by means of the motorized rolls 27, the second movement device 13 again translates the bar B toward the first movement device 11, but still raised with respect to the latter, for a length substantially equal to the position where the bend is to be obtained.

When the bar B has its portion that is to be bent disposed near the contrast pin 22, the clamping means 37 are activated, which clamp the bar B in such position and allow it to be subsequently bent by rotation of the rotating mandrel 20. In particular, the bending pin 21, going into contact with the bar B, forces the latter to wind around the contrast pin 22 to obtain the desired bending.

The rotating mandrel 20 is rotated to a position where a first segment of the bar B is in a position near to, or nearly interfering with, the second movement device 13, that is, with the casing 39 that supports the contrast rolls 29.

In this position, the support pin 33 is taken to a protruding position with respect to the plane on which the rolls 27 and 29 lie, the clamping means 37, which had been gripping a second segment of the bar B, release their grip on the latter, the actuators 30 distance the contrast rolls 29 from the motorized rolls 27, and the second translation means 32 translate the second movement device 13 to a retracted position under the work plane P.

The second segment of the bar B therefore remains constrained in three points of contact, that is, with the contrast pin 22, the bending pin 21, and laterally to the bend, with the support pin 33.

In this condition the rotating mandrel 20 is driven, rotating it further to bend the first segment of the bar B substantially by an angle of 180° around the contrast pin 22, without any constraints connected to interference with the contrast rolls 29 of the second movement device 13.

During this step, the support pin 33 contrasts the bending action exerted by the bending pin 21, and allows the correct execution of the bend.

Subsequently, both the bending device 12 and the support pin 33 are lowered, leaving the bar B free on the work plane of the machine, which, being slightly inclined, discharges the latter toward a collection zone of the bent articles.

It is clear that modifications and/or additions of parts may be made to the bending machine as described heretofore, without departing from the field and scope of the present invention.

For example (fig. 10), in another form of embodiment, instead of using a support pin 33, the function of support and contrast during the bending of the bar B may be carried out by the motorized rolls 27, by selective translation of the group of contrast rolls 29 only, which are taken to a condition of non-interference.

More specifically, the motorized rolls 27 are mounted on a first frame 51, provided with a first guide 52 disposed vertically and facing toward the contrast rolls 29.

Along the first guide 52 a second frame 53 is slidingly disposed, provided with a second guide 55, disposed horizontal and along which a support element 56 of the contrast rolls 29 is made to slide, in order to take them closer to/away from the motorized rolls 27.

The second frame 53 is displaced vertically along the first guide 52 by means of a first actuator 57, whereas the horizontal translation of the support element 56 along the second guide 55 is achieved by a second actuator 58.

Both the first frame 51 and the second frame 53 are moved in a group vertically by means of the second translation means 32.

More specifically, during the bending step, when the bar B is in a position of interference with the casing 39 supporting the contrast rolls 29 (fig. 7), the latter are translated vertically downward along the first guide 52 to take them completely under the bulk defined by the motorized rolls 27, and hence into a position of non-interference in order to bend the bar B.

During the step when the bending is being completed, the motorized rolls 27 remain protruding with respect to the work plane of the machine, to define a contrast with the bending action itself.

In another form of embodiment (fig. 11), the function of supporting and contrasting the bar B during the bending step is carried out by the clamping means 37, which in this particular case are made as a separate element with respect to the second movement device 13.

In this form of embodiment, the clamping means 37 comprise a first gripping part 65 and a second contrasting part 66 which, in normal use, acts as an abutment element of the bar B when the first part 65 is moved against the second part and thus clamps the translation of the bar B during the bending steps.

More specifically, the second part 66 is provided with a first guide 69 disposed vertically and facing toward the first part 65 on which a support frame 70 of the first part 65 is slidingly associated. The support frame 70 is provided with a second guide 71, disposed horizontal, along which the first part 65 is made to slide in order to take it closer to/away from the second part 66.

The support frame 70 is displaced vertically along the first guide 69 by means of a first actuator 72, whereas the horizontal translation of the first part 65 along the second guide 71 is achieved by a second actuator 73.

Both the first part 66 and the frame 70 are moved in a group vertically by means of translation means 75.

In particular, during the feed and bending steps of the bar B, both the first part 65 and the second part 66 are disposed substantially facing, coplanar with respect to each other, and protruding from the work plane P, in order to constrain the movement of the bar B during the bending steps.

When the bar B, in the bending step, begins to interfere with the casing 39 of the second movement device 19, the first part 65 of the clamping means 37 moves under the work plane P, leaving the second part 66 protruding.

The second movement device 13 is taken under the work plane P and the second part 66 acts as a contrast to the second segment of bar to complete the bending of the first segment.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of bending machine, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.