ELONGATED WORKPIECES

BACKGROUND OF THE INVENTION

The present invention relates to a roller bending machine for bending elongated workpieces, such as beams, bars, profiled sections, pipes and other semifinished elements that from an initial configuration with a rectilinear extent have to be bent in a desired manner to be destined to the making of structures of various type.

PRIOR ART

Roller bending machines for bending an elongated workpiece such as a profiled section, a bar etc. are known. The machines comprise a base to which the rollers are fitted for coming into contact with two opposite faces of the workpiece to subject the workpiece to a flexing action and thus bend the workpiece according to a given profile.

The rotation of the rollers, and a certain movement of one or more rollers with respect to the other rollers, with a thrust action on the workpiece, impose on the workpiece a deformation having a certain bend.

Two types of roller machines are currently known for bending elongated workpieces, which are disclosed below.

A first type of machines, generally indicated in the industry by the term“fixed geometry machine”, has rollers, for example, three rollers rotating around respective horizontal axes. More precisely, an upper roller is provided, the axis of which is fixed, in a stationary position on a vertical centre plane of the machine, and two side rollers arranged at a lower height, and spaced mutually symmetrically with respect to the vertical centre plane. The two, right and left, lower rollers are connected to hydraulic cylinders that can vary the respective position thereof. In particular, the axes of the two lower rollers are movable along trajectories approaching the upper roller.

During a bending cycle, the two lower rollers, in contact with a face of the workpiece to be bent, ascend along the tilted trajectories to the upper roller. The ascending movement of the lower rollers, and the consequent contrasting action exerted by the upper roller having the fixed axis, generate on the metal workpiece to be processed a flexing action intended to bend the workpiece to shape the workpiece into the desired bent profile.

This first type of machine is very widespread because of some strong points. A first strong point is the structural simplicity and simplicity of use of the machine. Another strong point of this machine is the flexibility of use that distinguishes the machine: the fact that the bending action occurs by the ascending movement of the side shafts enables a machining position be selected, i.e. the lying position of the workpiece being machined exiting the machine to be decided and the loading position of the workpiece upstream of the rollers to be decided. This occurs by arranging and moving the two side rollers in a position that is asymmetric with respect to the vertical centre plane, i.e. having the two lateral rollers at a quote that is different from one another in a desired manner.

This enables possible external machining accessories, such as spindles intended to intervene on the bent workpiece, to be combined with the machine downstream and/or upstream of the machining zone of the rollers. Further, the asymmetric position of the rollers enables the extending portion that cannot be bent, which is known in jargon as the“straight edge” to be reduced noticeably - but only on certain types of stiff and stable profiled section (such as profiled sections with a square section, solid bars, solid rods, etc.. The "straight edge" is the machining offcut, which is difficult to reuse, so it is at the centre of the attention of the user of the bending machine. This“straight edge” reduction is not however permitted if a stable profiled section has to be processed, but with a reduced section (a small profiled section with respect to the maximum performance that is achievable by the fixed-geometry machine used). Essentially, the fixed geometry machine is dedicated to processing only a certain range of workpieces, with gradually increasing proportions and structural resistance which have to be matched to the growing dimensions of the machine itself.

The "straight edge", as already explained, cannot be reduced or optimized over the entire range of profiled sections, especially those that have a yieldable cross section (asymmetric, hollow with thin walls, open, etc...). For these profiled sections, the "straight edge" that is obtainable by the machine is constrained to the fixed geometry of the latter, in a symmetric configuration of the side rollers, and becomes a secondary consideration. The attention to these profiled sections is mostly concentrated on the maintenance of the shape of the cross section after bending, trying to remain within a certain geometric tolerance range. This objective is achievable only by reducing the forces at play and increasing the contrast points on the workpiece (like reinforcing cores inside the profiled section or spindles, with the addition of further rollers, etc.). To reduce the forces at play, it would be necessary to increase the distance between the side rollers, this not being obtainable with the fixed geometry machine.

A second type of machine is known, which is generally indicated in the industry by the machine term“variable geometry”.

In the“variable geometry” machine, unlike the previously disclosed type, the two (lower) right and left side rollers are moved horizontally away from/towards one another, along respective aligned and horizontal linear trajectories.

The reciprocal horizontal“closing” or“opening” of the two side rollers determines a variation of the respective distances from the aforesaid centre plane (on which the axis of the upper roller lies) of the machine. The upper roller, in the variable geometry machine, is on the other hand movable vertically along the aforesaid centre plane.

During a bending cycle, the lower rollers with their axes remain in a stationary position, whereas the upper roller is lowered along the vertical trajectory. The descending movement of the upper roller, and the consequent contrasting action exerted by the lower rollers, subject the metal workpiece to a flexing action that bends it according to the desired shape profile. Variable geometry machines have a geometric configuration that can be considered to be“wide” or“narrow", symmetric or asymmetric according to the type of profiled section to be bent: if the profiled section is delicate, very instable and for this reason at risk of collapse, it will require a wide geometry to reduce the forces at play to the disadvantage of the straight edge (end portion of the profiled section that remains unbent and thus constitutes an offcut portion); if on the other hand the profiled section is tough and stable a“narrow” geometry will be opted for, but with greater forces in play, thus promoting a reduction of the "straight edges". In the fixed geometry machines disclosed above, this configuration possibility cannot be achieved.

The term“narrow” geometric configuration indicates a configuration with a small distance between the axes of the two (side) lower rollers and a small distance between two (side) lower rollers and the upper roller. Similarly, the term“wide” geometric configuration refers to a configuration with a significant distance between the axes of the two lower rollers and a significant distance between the lower rollers and the upper roller.

A variable geometry machine, with respect to a fixed geometry machine, has the advantage of permitting reciprocal adjustment at will of the two side rollers, to calibrate forces at play and adjust the size of the "straight edges".

Nevertheless, the variable geometry machine has strong limitations in terms of versatility and ability to interface with other machining accessories or apparatuses located on the process line.

These limitations make the use of a variable geometry machine significantly disadvantageous both from a technological and economic point of view in rather a wide area of the workpiece-bending industry. In other words, variable geometry machines always have significant dimensions, are extremely expensive and are used relatively little, in terms of working hours a year; this makes the purchase of such a type of bending machine financially disadvantageous in view of the current market situation.

To summarize, both the fixed geometry machines and the variable geometry machines that have just been disclosed, currently display clear limits linked to the respective technical architecture, and are unable to respond satisfactorily to the needs of the today’s world market for profile bending machines.

Essentially, the area of use of fixed geometry machines is limited to rather thin workpieces, to be subjected to bending processes with small radii; these workpieces have much smaller dimensions than steel girders or bars intended for the construction of large building works and engineering structures. Further, the fixed geometry machine is unsuitable for processing elements having“unstable” profiles, i.e. having a cross section that is easily subject to an undesired and irreversible geometric distortion.

On the other hand, the hypothesis of using a variable geometry machine for processing beams, angular elements, small tubular items, i.e. tubular items having reduced cross sections, is absolutely impractical, because of the kinematics and the bulky dimensions of the machine itself.

In a word, currently, each machine has a functional geometric configuration optimized for machining a limited range of workpieces, which are appropriate to the size of the machine itself. Accordingly, bending machines of significant dimensions with a“wide” geometric configuration are optimized and indicated exclusively for machining large- size workpieces, and vice versa, bending machines of small dimensions with a“narrow” geometric configuration are usable only for a range of structurally“light” profiles.

Examples of bending machines are also known from CN102632115 and CN106001200.

In the light of the limits set out above, the need remains to provide ameliorative solutions that are able to meet the increasingly demanding requests of the reference market.

OBJECTS OF THE INVENTION

One object of the invention is to improve the current systems for bending elongated metallic workpieces of any size and geometry, and thus supply a technical solution that is extremely versatile and suitable for a wide range of semifinished products to be processed, and is also financially advantageous.

In particular, one object is to provide a roller bending machine provided with great flexibility of use, which is able to process sectioned profiles of all shapes and sizes, which are extremely unstable, reducing the forces at play, but also stable profiled sections in which, for obvious reasons of cost, a reduction of the“straight edges” is required. The bending operation will be permitted on one machine alone, instead of passing on several distinct machines.

To sum up, the invention aims to respond effectively to current market needs, by providing a bending machine that is able to adapt, ensuring maximum operating efficiency, to any type of oblong semifinished product to be bent.

SHORT DESCRIPTION OF THE INVENTION

These objects and further advantages of the invention are achievable by a machine and a method according to what is defined in the enclosed claims.

In a first aspect of the invention, a roller bending machine is provided for bending an elongated workpiece, comprising

— a first roller suitable for acting on a first face of said elongated workpiece; — actuator means coupled with said first roller and configured for moving said first roller along a first plane lying transversely to an advancement direction for said elongated workpiece;

— a second roller and a third roller, arranged on sides opposite to said first transverse plane and suitable for acting on a second face of said elongated workpiece opposite said first face,

— further actuator means configured for moving said second roller and third roller to vary the respective distance thereof from said first plane,

— said second roller and third roller being configured for moving, by said further actuator means, along respective trajectories approaching said first roller, said trajectories extending transversely to said first plane,

— said first roller, second roller and third roller being arranged for bounding together a machining zone in which they cooperate to impose on said elongated workpiece a bending action, and

— a traction device, which is kinematically synchronizable with the translation of said first roller, and suitable for acting on a third inner face of said elongated workpiece, to exert, along a traction direction, a traction action, such as to move said elongated workpiece through said machining zone. In a second aspect of the invention, a method is provided for bending an elongated workpiece, comprising the steps of:

— driving actuator means to move a first roller, arranged for acting on a first face of said elongated workpiece, along a first plane lying transversely to an advancement direction for said elongated workpiece;

— providing a second roller and a third roller, arranged for acting on a second face of said elongated workpiece opposite said first face, and positioned on opposite sides with respect to said first transverse plane,

— driving further actuator means to vary the distance of said second roller and third roller from said first plane,

— moving, by said further actuator means, said second roller and third roller along respective trajectories that extend transversely to said first plane to approach said second roller and third roller to said first roller, and — driving a traction device to exert, along a traction direction, a pulling action on a third inner face of said elongated workpiece, and impose a traction action to move said elongated workpiece through a machining zone bounded by the said first roller, second roller and third roller and in which machining zone said first roller, second roller and third roller impose a bending action on said elongated workpiece.

Owing to the invention, the limits of current roller bending machines are overcome.

In particular, the machine according to the invention is, each time, configurable immediately according to the type of workpiece to be machined to operate according to a fixed geometry machine or according to a variable geometry machine.

Owing to the particular structural and kinematic features, the machine can take on a more or less“narrow” or more or less“wide” configuration according to specific needs.

In this manner, with a single machine, the typical advantages of fixed geometry machines and the typical advantages of variable geometry machines are obtained, and at the same time the limits inherent to the two known type of machine are overcome.

Essentially, the present invention provides a machine that could be defined as being multifunctional and having multiple geometry that is able to meet all the needs of the operators of the reference sector.

Other features and advantages will be clear from the appended claims, the description and the appended drawings.

SHORT DESCRIPTION OF THE DRAWINGS

The invention can be better understood and implemented with reference to the appended drawings, which illustrate some embodiments thereof by way of non limiting example, in which:

Figure 1 is a perspective view of a roller bending machine according to the invention;

Figure 2 shows the roller bending machine schematically in a first operating configuration during the bending of a beam with a reduced cross section;

Figure 3 shows, according to a side view, a guiding and correcting device of the machine in figure 2;

Figure 4 shows the roller bending machine schematically in the first operating configuration during bending of a beam having a wide cross section;

Figure 5 is a side view of the guiding and correcting device of the machine interacting with the beam;

Figures 6 and 7 show the roller bending machine in a second and a third operating configuration respectively, operating with asymmetric arrangements of the rollers.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the enclosed Figures, a roller bending machine 1 is shown that is used for bending elongated workpieces P of any shape and size, such as bars, beams, profiled sections, pipes and other semifinished elements to be bent, which are used in the construction of small and large structures.

In the non-limiting example shown in the Figure, the bending machine 1 is of the three-roller type having vertical rotation axes. Nevertheless, the machine 1 can be configured to have the rollers rotating around horizontal axes.

The roller bending machine 1 comprises a base structure 30 to which the various components disclosed below are fitted.

A first roller 2 is provided that is suitable for acting on a first face 3 of the elongated workpiece P to be bent, and actuator means 4 coupled with the first roller 2. The actuator means 4 in particular comprises a first actuator 4, for example a hydraulic cylinder or other equivalent, configured for moving the first roller 2 along a first plane Pl lying transversely to an advancement direction D _A for the elongated workpiece P. The machine 1 is further provided with a second roller 5 and with a third roller 6, arranged on sides opposite the aforesaid first transverse plane Pl, and suitable for acting on a second face 7 of the elongated workpiece P opposite the first face 3.

The first roller 2, the second roller 5 and the third roller 6 together bound a machining zone W in which they cooperate by suitable corresponding movements to impose a bending action on the elongated workpiece P. The machine 1 comprises further actuator means 8, 9 configured for moving the second roller 5 and the third roller 6 to vary the respective distance thereof D5, D6 from the aforesaid first plane Pl. In particular, the further actuator means comprises a second actuator 8 and a third actuator 9, for example hydraulic cylinders or other equivalents, arranged for driving respectively the second roller 5 and the third roller 6.

The second actuator 8 and the third actuator 9 are configured for moving the axes of the second roller 5 and of the third roller 6 so as to adjust respective force arms Bl, B2 defined between each second roller 5 and third roller 6 and first roller 2.

This configuration, together with the movement of the first roller 2 by the first actuator 4, enables the operation of the machine 1 to be adapted to the type of workpiece P to be processed, being able to intervene on and vary geometric parameters of the machine 1 (the force arms of the rollers).

For very heavy and robust beams, or also in the case of beams with a section that is very developed in height (dimension that extends from the first face 3 to the second face 7), it is possible to space apart more (“open”) the second roller 5 and the third roller 6, thus increasing force arms (Bl, B2) and consequently reducing the forces that act on the workpiece P and/or increasing the bending radii imposed on the latter.

From a comparison of Figures 2 and 4, the variation of the“geometry” of the machine 1 is clear, which is made possible owing to the first 4, second 8 and third 9 actuators.

Whilst the second 8, and the third 9 actuators generate a variation of the arms Bl, B2, the first actuator 4 adjusts the gap size A, A' necessary for inserting the elongated workpiece P. In the configuration of figure 4, Bl and B2 are greater than the configuration of figure 2.

The adaptability of the machine 1 for being able to bend both very“light” workpieces P and very“heavy” workpieces P’ is clear.

In Figures 2 and 3, a workpiece P is shown having a cross section T, and the machine 1 is set with a corresponding transverse size A of the machining zone W.

In Figures 4 and 5 a workpiece P’ of greater size is shown, having a cross section T’; in this case the machine 1 is set with a greater transverse size A’ of the machining zone W and has a greater relative space between the rollers 2, 5 and 6.

The machine 1 comprises a slide 20 supporting the first roller 2 and movable - by driving by the first actuator 4 - along a rectilinear trajectory Rl orthogonal to the advancement direction D _A along which the workpiece P moves in the machining zone W.

The possibility of moving the first roller 2 along the aforesaid rectilinear trajectory Rl, essentially along the centre plane of the machine 1, makes it possible to perform two different operations: adapting the transverse size A (often indicated by the term “space”) of the machining zone W to the cross section of the workpiece P, such as a beam, and, according to a possible operating mode of the machine 1, performing the proper bending operation, whilst the axes of the second 5 and third 6 roller remain in a stationary position (operating as a variable geometry machine).

The first actuator 4, the second actuator 8 and the third actuator 9 are drivable autonomously and independently of one another but, during a bending cycle, they can be commanded in a mutually coordinated manner and synchronized by a control unit Uc included in the roller bending machine 1.

In particular, as disclosed above, the control unit Uc is able to position relatively the first 2, second 5 and third 6 rollers on the basis of the dimensional/geometric features of the elongated workpiece P before the start of a bending cycle and is able to move one or more of these rollers, to impose the necessary bending force on the workpiece P during the bending cycle.

The second roller 5 and the third roller 6 are configured for moving, by the second 8 and third 9 actuators, along respective trajectories Tl, T2 approaching the first roller 2. These trajectories Tl, T2 extend transversely to the aforesaid first plane Pl.

In a first embodiment, shown in Figures 1 to 6, trajectories Tl, T2 are curvilinear trajectories Cl, C2 along which the respective rollers 5 and 6 approach/move away from the first roller 2. More precisely, the second roller 5 and third roller 6 are supported by respective support arms 12, 13 that are rotatable around respective rotation centres CRI, CR ₂ .

The second actuator 8 and the third actuator 9 are connected to the aforesaid arms 12, 13 and are configured for moving the axes respectively of the rollers 5, 6, according to the aforesaid curvilinear trajectories Cl, C2 approaching/moving away from, the first roller 2.

The curvilinear trajectories Cl, C2 extend symmetrically with respect to the first plane Pl.

In one embodiment, the roller bending machine 1 is provided with a traction device 10, which is kinematically synchronizable with the translation of the first roller 2, and suitable for pulling the elongated workpiece P (in this case an“FU-shaped beam), acting on a third inner face 31 of the elongated workpiece P, to exert along the direction D _AT a traction action that is such as to move the elongated workpiece P through the machining zone W. In another embodiment, the second roller 5 and the third roller 6 are supported by respective arms 14, 15 connected to the second actuator 8 and to the third actuator 9 respectively, the latter being configured for translating the respective axes of the rollers along respective linear trajectories Ll, L2 approaching/moving away from, the first roller 2, in which these trajectories Ll, L2 are tilted, mutually symmetrically, with respect to the first plane Pl and point to the first roller 2.

The possibility of moving the axes of the second 5 and third 6 roller approaching the first roller 2 (according to linear or planetary trajectories), enables the machine 1 to operate in the same manner as a fixed geometry machine: the second 5 and third 6 roller, approaching the first roller 2, generate the bending force contrasting the first roller 2, which is maintained with its axis in a stationary position.

The roller bending machine 1 is provided with a pair of guiding and correcting devices 11 arranged, upstream and downstream of the machining zone W, for guiding and correcting the advancing workpiece P.

Each guiding and correcting device 11 is provided with suitable revolving elements, such as oblong support rollers 17, supported by suitable adjustable slides, and wheel elements 16, suitable for acting on a face 3 of the elongated workpiece P.

The guiding and correcting devices 11 are angularly and axially adjustable in the three spatial directions (X, Y, Z) (as indicated by the arrows in Figures 2, 3, 4, 5) and act to guide the advancement and continuously correct the lying position of the elongated workpiece P during the bending process.

Owing to the possibility of wide regulation of position and orientation in space, the guiding and correcting devices 11 adapt to the various operating modes of the machine 1, i.e. with both the“narrow” geometric configuration and with the“wide” geometric configuration.

As already explained, the term “narrow” geometric configuration indicates a configuration in which the distance is reduced between the axes of the two rollers 5 and 6 and the distance between the two rollers 5 and 6 and the first roller 2. Similarly, the term“wide” geometric configuration refers to a configuration in which the distance between the axes of the two rollers 5 and 6 and the distance between the two rollers 5 and 6 and the first roller 2 is significant.

Figures 6 and 7 show two other possible operating modes in an asymmetric configuration of the rollers. The position of the second roller 5 is different from the position of the third roller 6. This makes it possible to combine with the machine 1, downstream of the machining zone W, possible external accessories or machining devices such as spindles intended to intervene on the bent workpiece.

The machine 1 according to the invention thus also has the typical strong points of a fixed geometry machine. From what has been disclosed, it is clear that the machine 1 according to the invention is suitable for being used successfully for bending small size elements, exploiting a fixed geometry configuration, but also large structural elements that are much requested in the field of large building constructions, by exploiting a variable geometry configuration.

In order to have an idea of the range of sizes that are proces sable owing to the present machine 1, the following values are indicated. The machine 1 can process beams that vary from class HEA 240, i.e. having transverse dimensions of 240 mm and 230 mm, (or also smaller dimensions) to the class“HEA” 550, i.e. beams having transverse dimensions of 300 mm and 540 mm, or also beams of a greater dimensional category.

Prior art machines are on the other hand sized and configured for processing a limited range of beams for example, HEA beams measuring 280 to 340, or HEA beams measuring 360 to 550.

Owing to its flexibility of use, the machine 1 according to the invention overcomes brilliantly the critical points that occur if it is necessary to process profiled sections having unstable sections, at risk of collapse, i.e. having reduced stiffness and thus being subject to the risk of deformation of the geometric shape thereof during the cold bending cycle.

This is achieved by exploiting the capacity of the machine 1 according to a“variable geometry” operating principle; in this case it is possible to move the two rollers 5 and 6 away from one another and subject the workpiece P, in several bending strokes, to a succession of slight incremental bending actions, successfully overcoming the critical points linked to possible instability of the shape of the cross section of the workpiece P.

To sum up, the machine 1 achieves the objectives declared above and has:

- simplicity of use thanks to the possibility of bending the workpiece P by the thrust exerted by the second and third rollers 5, 6 (with planetary or linear movement) on the first roller 2, whilst the first roller 2 remains in the fixed position;

- possibility of operating according to a variable geometry configuration by maintaining the second and third rollers 5, 6 in a stationary position and bending by the thrust of the first roller 2 moving along the rectilinear trajectory Rl;

- possibility of bending the workpieces P by arranging the rollers 5 and 6 in an asymmetric position to enable the external accessories which assist bending, such as spindles, etc, to be combined.

It is further considered that the machine 1 proposed here fully meets current market needs and requirements. It is further understood that what has been said and shown in the appended drawings has been provided merely by way of illustration of the method and general features, and of some embodiments of the machine 1 according to the present invention.

Other modifications or variations can be made to the entire machine 1 or to parts thereof and to the respective operating method whilst remaining within the scope of the claims.