The bending machine according to the invention is applied in the bending and shaping of metallic profiles, particularly but not only round pieces used for reinforcement purposes in reinforced concrete buildings.

Hereinafter, for reasons of simplicity, we shall refer to a specific use for shaping round pieces for reinforcement purposes with a diameter which may reach up to 30 mm and more.

BACKGROUND OF THE INVENTION The state of the art includes bending machines for round pieces used for reinforcement purposes; these machines comprise at least a drawing assembly associated with at least a bending assembly and a shearing assembly, and are employed to make reinforcement stirrups and/or rods which are shaped according to pre-defined angular or polygonal shapes.

The drawing assembly normally includes at least a drawing device consisting of one or more pairs of counter-rotating rolls, aligned on an axis which is orthogonal to the direction of feed of the round piece, or by drawing grippers which can be moved along the axis of feed of the round pieces to be bent.

In the case of round pieces fed from a reel, the drawing assembly normally also comprises straightening means located upstream, downstream or both upstream and downstream of the drawing device.

The bending assembly normally consists of a plate, associated with the relative rotation means, which includes

a bending pin in a peripheral position and, in a substantially central position, an abutment pin on the axis of which the plate usually rotates.

According to current legislation, the radius of curvature of the bends which can be made on round pieces to be used as reinforcement elements in buildings made of reinforced concrete must not be less than a value correlated to the diameter of the round piece itself.

However, this radius of curvature cannot have too high a value either, since this would entail an excessive rounding of the stirrup or a change in shape of the rod, making the stirrup or rod substantially unusable or in any case geometrically unsuitable for the structure to which they have to be applied.

Due to these legislative limitations concerning the radius of curvature of the round pieces used for building purposes, it is not possible, because of the physical dimensions of the abutment pin, to use a single bending assembly to perform every type of bending operation as the diameter of the rods to be bent varies.

Therefore, it is often necessary to replace the bending assembly because it is not able to shape the round pieces to a wide range of diameters, or to carry out different bends on the same round piece.

Therefore bending machines as are known to the art usually adopt bending assemblies of a type which can be dis- assembled from the bending machine, so that they can be replaced according to the diameter of the round pieces to be bent.

Some bending machines, however, include bending assemblies where only the abutment pins can be replaced.

In both cases, however, it is difficult and laborious to replace the bending assembly manually, or even the abutment

pins alone; these operations involve considerable periods of inactivity of the machine and therefore considerably lengthen the production cycle.

Moreover, it is necessary to keep at hand a plurality of spare parts and replacement elements, with problems of storage, retrieval, operating efficiency, etc.

Furthermore, the continuous repositioning and removal of the bending assemblies or abutment pins in their respective housing seatings in the long term cause a premature wear of the parts and/or problems of coupling between the parts, and thus compromise the working accuracy of the bending machine.

There are two more factors to take into consideration, which have always caused problems in the search for rapid and efficient solutions to replace at least partly the bending assembly.

The first factor is that bending machines must be able to perform consecutive left-and right-hand bends on the round pieces positioned on the work surface, and therefore it must be possible to position the bending disk with the bending pin on one side and the round pieces on the other side, without interruptions to the cycle or manual intervention.

Another factor is that the bending assembly, which substantially defines the work plane in the bending zone, is connected to a plate, and it must be possible to translate this whole plate orthogonally to the axis of the round pieces in order to adapt the position of the central pin, when the diameter is changed, to the axis of the round piece.

A further point to consider concerns the work place, which is full of dust, scale and particles which become detached from the round pieces during the bending operations and infiltrate into the spaces, and thus cause problems with the mechanical connections.

Two proposals to solve the problem of replacing the bending assembly as the diameter of the round piece to be bent varies are shown in EP-A-517637 and EP-A-519865, which do not resolve all the shortcomings mentioned above, however.

These solutions provide to arrange, below the plane of feed of the round pieces, a table rotating on an axis orthogonal to the plane of feed.

The table supports a plurality of bending assemblies, each including a respective abutment pin and a respective bending pin each having their own specific diameter.

The specific bending assembly selected according to the diameter of the round piece to be bent and/or the type of bends to be made is first taken to the correct working position by rotating the table, and then it is lifted by specific lifting means so as to be taken to the level of the plane of feed of the round pieces.

Then, the bending assembly is made to rotate so as to make the various bends on the round piece.

Because of their construction and structure, these solutions are only suitable to be used on machines which work metallic wire or in any case round pieces with a small diameter, not round pieces used to make rods or stirrups for reinforcement purposes, which can have a diameter of 30 mm and more.

Using tables to carry the bending assemblies which rotate around an axis orthogonal to the plane of feed of the rods is not a practicable solution when the value of the diameter of the rods to be bent requires the use of large-size bending assemblies, inasmuch as it causes an unacceptable increase in the spaces occupied below the work plane.

A further disadvantage of the solutions proposed in these documents is that the entire bending assembly, comprising

the plate with the relative bending and abutment pins assembled thereon, is replaced.

Each plate is directly associated with the gear drive element suitable to make it rotate in order to perform the bending cycles.

It should also be noted that all the bending assemblies are constantly engaged with the drive element, even if only one of them is positioned above the bending plane during the working condition.

This causes an obvious and useless waste of power.

Moreover, when the bending assembly is in its raised condition, and elastically contrasted, it makes it problematical to transmit the high power needed to bend large-size round pieces.

A further disadvantage of these solutions is that, because of the gaps and interstices between the bending assemblies and the work plane, particularly in the case of EP'865 where the bending assemblies are supported on respective grooved shafts, the abundant dust and waste which is generated during the bending cycles can quickly cause working conditions to become untenable, and therefore frequent maintenance and restoration is required.

The present applicants have designed, tested and embodied this invention to overcome the shortcomings of the state of the art and to obtain an embodiment which is efficient and functional in operation.

SUMMARY OF THE INVENTION The invention is set forth and characterised in the main claim, while the dependent claims describe other characteristics of the idea of the main embodiment.

The purpose of the invention is to obtain a bending machine which will shape round pieces for use as reinforcement elements in the best possible manner and in

accordance with the legal requirements concerning the radius of curvature, without needing a store of abutment pins or bending assemblies to replace every time the diameter of the round piece to be shaped is varied.

Another purpose of the invention is to reduce the periods of inactivity of the bending machine and thus considerably improve the productivity and efficiency thereof.

The bending machine according to the invention comprises at least a drawing assembly, at least a shearing assembly and at least a bending device comprising a plurality of bending tools which can be selected individually and selectively and each of which includes an abutment pin of a different diameter.

According to a variant, the bending machine comprises two or more bending devices, for example one arranged upstream and one arranged downstream of the drawing assembly.

According to the invention, each bending tool is used in the shaping of round pieces for reinforcement purposes of a defined range of diameters.

According to a variant, each bending tool is used in the execution of a defined range of bends on the same round piece.

Each of the bending tools consists of a plate-type support on which the bending pin and the abutment pin are mounted, and is assembled on the periphery of a rotary positioning device which lies below the work plane.

The positioning device is suitable to rotate around an axis substantially parallel to the plane of feed of the round pieces to be bent so as to allow the angular movement of the bending tools, on a plane substantially orthogonal to the plane of feed, until they are in a position wherein they can be raised to assume an active position substantially lying on the work plane of the bending machine and wherein

both the pins, the bending pin and the abutment pin, position themselves astride the round pieces to be bent.

In a preferential embodiment, the specific bending tool selected is made to pass to the active position by raising the entire positioning device.

In the operating position, the bending tool selected for the specific bending cycle is constrained to a rotary plate, substantially complanar with the work plane, which causes it to rotate so that the bends may be made on the round piece.

For this purpose, the rotary plate has an insertion seating of a shape mating with that of the plate-type support of the bending tool.

Movement is transmitted to the rotary plate by its periphery, by means of belt means, chain means or gears.

With this invention, therefore, it is not necessary to include any drive or motor element below the work plane inasmuch as, once the specific bending tool selected has been positioned in the working position, the movement of the rotary bending plate takes place in a perfectly conventional manner with peripheral drive means such as are known in the state of the art.

The invention therefore does not change the bending assembly in its entirety, but allows to replace only the bending tool inserted inside a bending plate which is otherwise conventional both in its structure and in its relative drive mechanisms.

According to a variant, each bending tool may also assume a vertically intermediate position between the pre- determined selection position, lowered and angular, and the raised operating position wherein the bending tool is constrained to the rotary plate.

The intermediate position is located at a level beneath the work plane, so as not to interfere with the round piece

passing through and is assumed by the bending tool when the direction of bending has to be changed, from right to left or vice versa.

In the intermediate position, the bending tool can be made to rotate solid with the rotary plate without interfering with the round pieces; this causes the reciprocal position of the bending pin and the abutment pin to be inverted with respect to the round piece to be shaped.

BRIEF DESCRIPTION OF THE DRAWINGS The attached Figures are given as a non-restrictive example and show some preferential embodiments of the invention as follows: Fig. 1 shows in diagram form and in section a part of the bending machine according to the invention during the step when the bending assembly is replaced; Fig. 2 shows the bending machine as in Fig. 1 during the step when the position of the bending assembly is inverted; Fig. 3 shows the bending machine under operating conditions; Fig. 4 shows the bending machine according to the invention in diagram form and from above; Figs. 5 and 6 show two variants of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the attached Figures the reference number 10 denotes generally the bending machine according to the invention, shown in diagram form and in part.

The bending machine 10 comprises a drawing assembly with a drawing device 11 including counter-rotating rolls 15 to feed forward on its axis the round piece 16 to be shaped (Fig. 4).

Round piece 16 should be taken to include a bundle of round pieces.

The situation is exactly the same, although it is not

shown here, if the drawing assembly consists of drawing grippers which can move on their axis with a to-and-fro movement.

The bending machine 10 also comprises a bending device 32 comprising a rotary plate 20, arranged complanar with the plane of feed 17 of the round pieces 16, suitable to cooperate with a plurality of bending tools 12 assembled peripherally on an angular positioning device, in this case a rotary drum 14, arranged entirely below the plane of feed 17.

In the case shown in Figs. 1-3, there are four bending tools 12 assembled on the drum 14, arranged symmetrically at 90° one from the other.

The center of rotation of the drum 14 lies on the vertical plane substantially orthogonal to the work plane 17 and containing the longitudinal axis of the round piece 16.

The drum 14 rotates around an axis, in this case horizontal, substantially parallel to the work plane 17.

According to a variant which is not shown here, there are two different bending devices 32 with relative bending tools 12, one upstream and one downstream of the drawing device 11.

Upstream and downstream of the bending position there are also respective pairs of grippers 29 which act on the round piece 16 with a contrasting function during the making of the bends.

Each of the bending tools 12 comprises a support 13, in this case square, on which a bending pin 18a and a mating abutment pin 18b are mounted, each having its own defined diameter.

The support 13 is shaped to mate with a seating 21 to be found substantially centrally on the rotary plate 20.

Rotatory motion is transmitted to the rotary plate 20

during the bending step by its periphery, in a substantially conventional manner, by gear means 31.

The rotary plate 20 is guided in its rotation on the work plane, in this case, by guide wheels 22 or by a guide ring.

According to a variant which is not shown here, the rotary plate 20 is moved peripherally by belt means or chain means.

In the embodiment shown here, the bending tools 12 are attached to the rotary drum 14 by means of constraining pins 19.

The constraining pins 19 cooperate with means which are not shown here which prevent any angular displacement, or any movement whatsoever, of the support 13 during the rotation of the drum 14, but allows the support 13 to rotate when, in its operating position, it is made solid with the rotary plate 20.

The bending tools 12 each have an abutment pin 18b of a different diameter which is employed to shape a defined range of diameters of round pieces 16.

The rotary drum 14 is mounted on a bearing frame 26 which is supported by a plate 27, arranged complanar with the work plane; the rotary plate 20 is located in an aperture of the plate 27.

The wheels 22 which guide the rotary plate 20 in its rotation are mounted on the said plate 27.

The rotary drum 14 is vertically movable with respect to the bearing frame 26 by means of lifting means 23 defined by at least an actuator 24 and associated with movement blocks 25.

The supports 13 can be inserted inside the central seating 21, thus defining a locking connection of the supports 13 and the rotary plate 20; it is thus possible to make the bending tools 12 temporally solid with the plate 20 so that the bends can be made on the round piece 16 to be shaped.

Moreover, this connection does not cause any gaps or interstices inside which dust or waste generated during the bending cycles can infiltrate.

In this case, the rotary plate 20 has a lead-in bevel 30 on the lower part which facilitates the insertion and lock- in connection of the bending tools 12 selected on each occasion according to the diameter of the round pieces to be bent and/or the type of bends to be made.

According to the invention, at the step when the bending tool 12 which will be used to shape the round piece 16 is selected, according to the radius or the type of curvature to be made, the bending tools 12 are all underneath the rotary plate 20 in a non-operative position (Fig. 1).

To select the bending tool 12 to be used, the procedure is as follows: the drum 14 is rotated until the specific bending tool 12 selected is taken to a position defined angularly and exactly below the central seating 21.

The bending tool 12 is then inserted, in its operating position, into the central seating 21 and is coupled with the rotary plate 20 so as to form a single body therewith; it is then made to rotate by the rotary plate 20 so as to make the bends on the round piece 16 (Fig. 3).

The insertion of the bending tool 12 is obtained by moving the drum 14 upwards by means of the lifting means 23.

When it is necessary to invert the reciprocal positions of the bending pin 18a and the abutment pin 18b with respect to the round piece 16, in order to vary the direction of the bends, the drum 14 is partly lowered with respect to the work plane 17, thus taking the bending tool 12 to an intermediate position wherein it is still coupled with the rotary plate 20, but is in a position underneath the work plane 17 so that it does not come into contact with the round piece 16 (Fig. 2).

In this intermediate position, the bending tool 12 is made to rotate to the desired positioning of the bending pin 18a and the abutment pin 18b; it is subsequently returned to the operating position so that further bends may be made on the round piece 16 by means of lifting the drum 14.

When it is desired to replace the bending tool the drum 14 is lowered until any contact between the support 13 and the rotary plate 20 is eliminated; the drum 14 then rotates until it positions the selected bending tool 12 angularly.

In this case, the plate 27 is associated with an actuator 28 which allows it to move orthogonally to the direction of feed of the round piece 16, thus making it possible to adapt the position of the central abutment pin 18b with respect to the round piece 16 to the variable diameter of the said central pin 18b.

In the variant shown in Figs. 5 and 6, a bending tool 12a has not only the bending pin 18a and the abutment pin 18b but also a shears element 33 which can be used during or at the end of the bending cycle so as to shear the round piece 16 or the shaped and finished piece.

Fig. 5 also shows the variant wherein a specific shearing tool 133 is peripherally assembled on the rotary drum 14; the shearing tool 133 is assembled on a relative support 13 and is taken to the operating position cooperating with the rotary plate 20 instead of a bending tool 12 and in the same manner thereas, in order to perform any desired shearing operations on the round piece 16.

Fig. 5 also shows how it is possible to assemble five or more bending tools 12 on the drum 14 according to their size and the space available.

Fig. 6 shows a further variant which provides to assemble on the plate 27 shears elements 33 which can be selectively retracted and used to perform specific shearing operations on the round piece 16 which is to be bent or has already been bent.