"BENDING MACHINE FOR OBLONG METAL ELEMENTS, AND RELATIVE METHOD" %

FIELD OF THE INVENTION The present invention concerns a bending machine for oblong metal elements to be shaped, such as for example reinforcement bars, sheets, round pieces, sections, tubes or others, made for example from drawing, rolling, extrusion, profiling or other operations, with diameters or thicknesses that range from about 5 mm to about 45 mm. In particular, the bending machine according to the invention comprises at least a bending unit and a contrasting unit around which the bending unit effects the shaping of the oblong metal element.

BACKGROUND OF THE INVENTION

Bending machines are known, for oblong metal elements to be shaped, such as for example reinforcement bars, sheets, round pieces, sections, tubes or others, made for example from drawing, rolling, extrusion, profiling or other operations. Known bending machines essentially consist at least of a bending support, or mandrel, generally disk-shaped, defining a bending plane and provided centrally with a contrasting element. On one radius of the mandrel a bending pin is provided, substantially co-planar with the contrasting element. The bending pin is able to rotate, in both a clockwise and anti-clockwise direction, around the contrasting element, so that the shaping of the oblong metal element occurs due to plastic deformation around the contrasting element.

It is known in the state of the art to bend an oblong metal element in a two- directional manner, that is, first in one direction and then in the other, to shape it according to a desired geometry, for example "S" shaped. In order to perform this operation, it is necessary to take the bending pin first to one side, for example to the left, with respect to the axis of feed of the oblong element, to bend it to the right, and then to the opposite side, in order to bend it to the left.

This operation entails the need to make the bending pin pass from one side to the other with respect to the oblong element.

To this purpose it is known to move the mandrel together with the relative bending pin, keeping the contrasting element stationary.

In known machines, in fact, the mandrel and the bending pin are moved

between a raised operating position, in which the latter interferes with the bending plane of the oblong element, and a lowered retracted position in which the bending pin too is below the bending plane of the oblong element.

In this way, in the retracted position, a rotation of the mandrel determines the passage of the bending pin from one side to the other of the oblong element without interfering with it.

One of the main disadvantages of the known device is the complexity of the design, production and maintenance of the various mechanical members that cause the movement of the mandrel, associated with the fact that in any case it is necessary to guarantee the possibility for the mandrel to rotate and apply high torques, in order to make the bend on one or more oblong elements simultaneously.

This disadvantage entails an increase in the working times and the costs of production, and also the bulk of the bending machines constructed in this way. In known bending machines, the distance between the contrasting element and the bending pin is substantially fixed and depends on the sizes of the disk of the mandrel.

Bending machines are also known, in which the distance between the contrasting element and the bending pin is adjustable, to position the bending pin in different radial positions on the disk of the mandrel. This adjustment on the one hand entails the need to provide mandrels with large sizes, so as to allow ample variations, and on the other hand can only be carried out when the machine is stopped, thus increasing production times.

Furthermore, the disk type conformation of the mandrel necessarily entails a circular movement of the bending pin, thus allowing to make only bends with a regular and predefined radius of curvature, which limits the bending potentialities of the known machine.

One purpose of the present invention is to achieve a bending machine that allows to bend at least a bar, for example metal, having a diameter even of several tens of millimeters, both in one direction and also in two directions, without needing to provided complex movement members that allow the bending pin to pass from one side to the other of the bar to be bent.

Another purpose of the present invention is to achieve a bending machine that

allows to adjust the distance between the contrasting element and the bending pin, also with the bending machine functioning.

Another purpose of the present invention is to achieve a bending machine which can perform not only circular bends, but substantially of any shape and 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.

SUMMARY OF THE INVENTION 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 bending machine according to the present invention is applied to bend oblong elements, for example metal bars, and comprises a fixed contrasting unit, a bending support defining a bending plane on which the oblong element is able to be positioned and moved, and at least a bending unit, mounted mobile around the fixed contrasting unit so as to bend the oblong element in cooperation with the contrasting unit.

According to a characteristic feature of the present invention, the contrasting unit is mounted on the bending support, while the bending unit is disposed elevated and distanced from the bending support, moving toward the contrasting unit when it is required to make the bends, and distancing itself from it at least between one bend and the next.

The bending unit comprises at least a bending pin mobile vertically between a first bending position in which it is lowered and approaches the contrasting unit so as to make the bend, and a second movement position in which it is raised and distanced from the contrasting unit at least by a distance enabling it to pass above the oblong element and be positioned without distinction on one side or the other of it. The bending unit also comprises at least a movement arm, disposed above the contrasting unit, and able to support and move the bending pin, both to make the bend and also to position it with respect to the contrasting unit before and after the bend is made.

The machine according to the present invention therefore allows to make bends and shapes on the oblong metal element easily and quickly, both to the right and to the left, and substantially of any shape, with respect to an axis of feed of the metal element, with the bending pin making a vertical movement and consequently passing over the metal element to be bent.

In this way, the movement of the bending pin, to pass physically from one side to the other of the oblong metal element, takes place from above and is independent from and not limited by the bending support and the bending movement of the pin itself. With the present invention we therefore obtain a simplified design, production and maintenance of the various mechanical members.

In one embodiment of the invention, the bending unit comprises two movement arms able to slide reciprocally with respect to each other and able to move the bending pin in pantograph fashion with respect to the contrasting unit. In this way the bending pin can assume substantially any position whatsoever with respect to the contrasting unit, and make different types of bend, not necessarily with a single angle.

Furthermore, with the present invention, since it is possible to move the bending pin as desired with respect to the contrasting unit, its distance from the contrasting unit can also be selectively adjusted, not only when the bending machine is functioning, but also during the bending of the oblong metal element.

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 view from above of a first form of embodiment of a bending machine according to the invention;

- fig. 2 is a schematic lateral view of the machine in fig. 1 ;

- fig. 3 shows an enlarged detail of fig. 2; - fig. 4 is a schematic view from above of a second form of embodiment of a bending machine according to the invention;

- fig. 5 is a schematic lateral view of the machine in fig. 4;

- figs. 6a, 6b, 6c and 6d show a sequence of changing the contrasting cylinders of

the bending machine according to the present invention;

- figs. 7a, 7b, 7c, 7d, 7e and 7f show a sequence of bending steps made with the bending machine according to the present invention. DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT

With reference to fig. 1, a bending machine 10 according to the present invention is able to bend by a desired angle, up to 180° and more, in this case one or more metal bars 11, with a diameter of up to about 40 mm.

The metal bar 1 1 is fed along an axis of feed "X" by a feed unit, of a known type and not shown in the drawings, disposed upstream of the bending machine 10.

The machine 10 according to the invention comprises a fixed frame 12 which defines a bending plane "P", a contrasting element 13, mounted substantially vertical on the frame 12, and a bending unit 15 mobile with respect to the contrasting element 13 on a plane substantially parallel to and above the bending plane "P".

The bending unit 15 comprises a bending pin 16 mounted mobile perpendicularly to the bending plane "P", and a pair of movement arms, respectively a first 17 and a second 19, which move the bending pin 16 parallel to the bending plane "P".

The movement of the bending pin 16 substantially perpendicular to the bending plane "P" is actuated by a linear actuator 20.

The linear actuator 20 is mounted at one end of the second 19 of the two movement arms, so as to allow the selective positioning of the bending pin 16 between a first bending position, lowered, in which it is substantially co-planar with the contrasting element 13, and a second movement position, raised, in which it is raised with respect to the contrasting element 13.

In this way, in its first bending position and in combination with the contrasting element 13, the bending pin 16 is able to bend the metal bars 1 1 whereas, in its second movement position, due to the effect of the movement imparted by the movement arms 17 and 19, it can distance itself from the bending plane "P" by a distance that enables it to pass above the metal bars 11 disposed on the bending plane "P".

The first movement arm 17 is mounted sliding on a raised structure 21 of the frame 12, in this case in a direction substantially parallel to the axis of feed "X" of the metal bars 11.

In particular, the first movement arm 17 comprises a first movement plate 22 mounted sliding along a corresponding beam 23 of the raised structure 21.

The beam 23 comprises laterally two sliding guides 25 (fig. 3) with a substantially trapezoid section, on which coordinated sliding blocks 26 slide, solid with the first movement plate 22.

The substantially trapezoid and coordinated shape of the sliding guides 25 and the sliding blocks 26 not only allows a precise linear sliding, but also guarantees the stable coupling of the first movement plate 22 and the beam 23, even in the event that the bending requires very high torques.

The first movement arm 17 also comprises a first actuator member 27 (figs. 1 and 2) attached on one side to the beam 23 and on the other side to the first movement plate 22.

The second movement arm 19 is mounted sliding on the first movement arm 17, in this case, in a direction substantially parallel to the axis of feed "X" of the metal bars 11.

In particular, the second movement arm 19 comprises a second movement plate 29 mounted sliding on a lower surface of the first movement plate 22.

The first movement plate 22 comprises laterally two sliding guides 30 with a substantially trapezoid section, on which coordinated sliding blocks 31 slide, solid with the second movement plate 29.

In this case too, the substantially trapezoid and coordinated shape of the sliding guides 30 and the sliding blocks 31 not only allows a precise linear sliding, but also guarantees the stable coupling of the second movement plate 29 and the first movement plate 22, even in the event that the bending requires substantially high torques.

The second movement arm 19 also comprises a second actuator member 32 attached on one side to the first movement plate 22 and on the other side to the second movement plate 29.

The bending machine 10 also comprises, in this case, two clamping grippers 33, of a substantially known type and not described in detail here, mounted

upstream and downstream of the contrasting element 13, and whose jaws are disposed on opposite sides with respect to the axis of feed "X" of the metal bars 11, so as to clamp the latter temporarily during the positioning and bending steps.

In this case, the contrasting element 13 can be selectively replaced by other analogous contrasting elements 13 having different shape and size.

In this way, the metal bars 11 can be bent with different bending radii and shapings.

In particular, each contrasting element 13 comprises a pair of contrasting cylinders 35 having an equivalent diameter. The two contrasting cylinders 35 are mounted on a support plate 36 so as to be reciprocally distanced to define a housing interspace for the metal bars 11.

Each support plate 36 can be selectively associated with the fixed frame 12 by' positioning the support plate 36 in a corresponding positioning aperture 37 made on the frame 12. Furthermore, each support plate 36 comprises four positioning bushings 39 in which, in a position when the support plate 36 is coupled to the frame 12, coordinated positioning pins 40 are able to be inserted (figs. 6a-6d).

The positioning pins 40 are advantageously mounted facing downward on a lower surface of the frame 12 and have an ample coupling play, for example 3 mm, with the relative positioning bushings 39.

In this way, the possibility of metal slag and/or other impurities depositing on the positioning pin 40 and/or the positioning bushing 39, which would compromise the correct coupling of the two, is reduced to a minimum.

Each support plate 36 is associated at the lower part with a lifting member 41, for example hydraulic, in order to lift it and lower it vertically, with the relative contrasting cylinders 35, with respect to the bending plane "P".

In this way, the support plate 36 is selectively moved between a lowered position, in which both the support plate 36 and the contrasting cylinders 35 are completely below the bending plane "P", and a raised position, in which the support plate 36 is substantially co-planar with the bending plane "P" and the contrasting cylinders 35 are completely above the bending plane "P"

In the raised position, the positioning pins 40 are inserted in the positioning bushings 39.

The bending machine 10 also comprises a store 42, in which the support plates 36 are positioned, each having a relative pair of contrasting cylinders 35 of different size and/or shape (figs. 1, 2 and 4, 5).

In particular, the store 42 comprises a rotary cart 43 disposed completely below the bending plane "P" and on which all the support plates 36 are mounted, with the relative contrasting cylinders 35 and lifting members 41.

In this way, the rotary cart 43 selectively positions a determinate support plate 36 in correspondence with the positioning aperture 37 of the frame 12. From this condition, the lifting member 41 takes the relative plate directly from the lowered position to the raised position.

According to the form of embodiment shown in figs. 1, 2 and 3, the rotary cart 43 moves linearly in a direction substantially parallel to the axis of feed "X" of the metal bars 11.

In this case, the mobile cart 43 is moved laterally with respect to the axis of feed "X" and the lifting member 41 is conformed so as to move the relative support plate 36 laterally into alignment with the positioning aperture 37, before it is lifted to the raised position.

According to the variant shown in figs. 4 and 7, the mobile cart 43 is disposed in a direction substantially transverse to the axis of feed "X" of the metal bars 11. In this case, the mobile cart 43 moves the support plates 36 directly below the positioning aperture 37, so that the lifting member 41 can lift the relative support plate 36 directly into the raised position.

The bending machine 10 according to the present invention functions as follows. Initially, the linear actuator 20 keeps the bending pin 16 in its second movement position, above the metal bars 11.

From this second raised position, depending on the type of bend to be made, the bending pin 16 is selectively moved co-planar to the bending plane "P" and with respect to the contrasting element 13 by means of the reciprocal movement of the two movement arms 17 and 19, until a specific starting position is reached.

With particular reference to figs. 1 and 2, the bending pin 16 is shown in a continuous line, to the right of the axis of feed "X" of the metal bars 11 and, in a line of dashes, to the left of the axis of feed "X" of the metal bars 11.

Once the specific starting position has been reached with respect to the contrasting element 13, the bending pin 16 is taken to its first bending position substantially co-planar to the contrasting element 13.

Once the two jaws of the relative clamping grippers 33 have been activated, so as to fix the position of the bars 11, the two actuator members 27, 32 of the two movement arms 17 and 19 are activated in a coordinated manner, so as to make the bend on the metal bars 11, to the left or to the right, around the relative contrasting element 13.

Furthermore, thanks to the movement made by the two movement arms 17 and 19, the bending pin 16 can be positioned, both before and also during the bending, substantially in any position with respect to the contrasting element 13, and can thus make shapings of the metal bars 11 substantially of any shape.

The diameter and/or shape of the contrasting element 13 determines the radius and/or shaping of the bend made. If it is necessary to change the sizes of the contrasting element 13 in order to make a different bend, the support plate 36 to be replaced is taken by the relative lifting member 41 to its lowered position.

Then, the rotary cart 43 is moved until it takes the support plate 36 with the desired contrasting cylinders 35 into correspondence with the positioning aperture 37.

Once this position has been reached, the relative lifting member 41 lifts the support plate 36 from its lowered position to its raised position, to take the relative contrasting cylinders 35 to an operating condition for bending.

Since it is carried out substantially automatically, this operation does not require an intervention of the workers, nor long downtimes for equipping the machine, allowing to bend metal bars 11 with different bending radii as shown for example in the sequence in figs. 7a-7f.

It is clear, however, that modifications and/or additions of parts or steps may be made to the bending machine 10 as described heretofore, without departing from the field and scope of the present invention.

For example, it comes within the field of the present invention to provide that the sliding blocks 26 and 31, and the coordinated sliding guides 25 and 30, have a cross section of a different shape, other than trapezoid, but in any case suitable to

support high bending torques.

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