The present invention generally relates to bending tools and, in particular, to a bending die which can be used in a press brake to deform, by bending, sheet-like components such as sheet metal or the like.

Press brakes are usually equipped with one or more punches, which are typically operated by hydraulic actuators, adapted to press sheet-like components, typically made of sheet metal, against a bending die. In a widespread embodiment, this bending die is provided with a hollow housing having a substantially cross-sectional V-shape. In the rest position the punch is spaced from the bending die to make it possible to insert a sheet-like component to be bent between the punch and the die. In the working position, the lower end of the punch is pushed towards the hollow housing of the bending die, consequently pushing the sheet-like component inside this hollow housing to carry out the bending of the sheetlike component. When bent, the sheet-like component has therefore a profile which is substantially corresponding to the profile of the hollow housing of the bending die.

Before bending, the portion of the surface of the sheet-like component to be bent rests on the upper side edges which delimit the hollow housing of the bending die. As the punch progressively pushes the sheet-like component towards the hollow housing of the bending die, this sheet-like component scrapes on the upper side edges which delimit the hollow housing. Both minor surface damages on the sheet-like component being processed, and excessive wear of the upper side edges which delimit the hollow housing of the bending die can be therefore caused by the sheet-like component scraping. The sliding friction between the sheet-like component and the upper side edges which delimit the hollow housing of the bending die can also lead to an increase in the force required to carry out the bending. Bending dies have been therefore provided which are equipped with a pair of substantially cylindrical bars placed at the upper side edges which delimit the hollow housing of the bending die. Each bar, which usually extends along the entire length of the bending die, is partially and rotatably inserted into a respective concave seat, having a substantially arc-shaped cross-sectional shape. The portion of the bar which is not housed inside the respective concave seat therefore forms the contact surface with the sheet-like component being processed. This contact surface can be either flat or curved depending on the embodiment of the bending die.

In the latter type of bending die, the tangential force transmitted by the sheet-like component to the contact surface of the bars causes a partial rotation of the bars inside their respective concave seats. Each of these bars therefore acts as a sort of tilting rotating roller or insert which makes it possible to eliminate, or at least to limit, sliding phenomena on the sheet-like component being processed.

An embodiment of a bending die equipped with bars having curvilinear contact surfaces, which thus act as rollers, is disclosed in document JP-A-2005329414. An embodiment of a bending die equipped with bars having flat contact surfaces, which thus act as tilting rotating inserts, is disclosed instead in document JP-A-2016193442.

These bending dies according to the prior art, while ensuring a better aesthetic result on the bent sheet-like components compared to the bending dies without rollers are, however, not free from some drawbacks. A first drawback consists in the fact that traditional bending dies equipped with tilting rotating inserts cannot obtain particularly small (acute) bending angles for the sheet-like components. Another drawback consists in the fact that the rollers and/or the tilting rotating inserts require a plurality of elastic elements for their correct repositioning following each single bending operation. The presence of this plurality of elastic elements on the bending die makes the manufacturing process thereof particularly complicated and costly.

The object of the present invention is therefore to provide a bending die for a press brake which is capable of solving the aforementioned drawbacks of the prior art in an extremely simple, economical and particularly functional way.

In detail, it is an object of the present invention to provide a bending die for a press brake which allows to obtain particularly small (acute) bending angles for the sheet-like components being processed.

Another object of the present invention is to provide a bending die for a press brake which is particularly simple and economical to manufacture compared to traditional bending dies equipped with rollers.

These and other objects according to the present invention will be achieved by providing a bending die for a press brake as set forth in claim 1. Further features of the invention are highlighted by the dependent claims, which are an integral part of the present description.

The features and advantages of a bending die for a press brake according to the present invention will be clearer from the following exemplifying and hence non-limiting description, referring to the attached schematic drawings in which:

Figure 1 is a perspective view of a first embodiment of a bending die for a press brake according to the present invention;

Figure 2 is a vertical sectional view of the bending die in figure 1, shown in a first working position;

Figure 3 is another vertical sectional view of the bending die in figure 1, shown in a second working position;

Figure 4 is a vertical sectional view of an embodiment of a bending die similar to the one in Figure 1; and Figure 5 is a vertical sectional view of an embodiment of a bending die for a press brake according to the present invention.

With reference to the figures, some preferred embodiments of a bending die for a press brake according to the present invention are shown. Whatever the embodiment, the bending die is indicated as a whole with reference number 10 and can be mounted onto a press brake (not shown) which is designed to bend sheet-like components S (schematically illustrated in Figures 2 and 3), which are typically made of sheet metal. The bending die 10 comprises a main body 12 which is connectable to a movable or fixed part of the press brake. This main body 12 extends along a longitudinal direction L (shown in Figure 1) and comprises a base portion 14 and a pair of opposite side walls 16, 18, which extend from the base portion 14 and both extend along the longitudinal direction L. The main body 12 also comprises at least one hollow housing 20, which is at least partially delimited by the side walls 16, 18 and also extends along the longitudinal direction L.

At the end edges of the side walls 16, 18, which substantially coincide with the upper end edges of these side walls 16, 18, respective support means 22, 24 are obtained which can tilt along an axis X substantially orthogonal to the longitudinal direction L or, in other words, can preferably tilt from top to bottom. In their rest position (shown for example in Figure 1), these tilting support means 22, 24 are adapted to receive and support a sheet-like component S to be bent and allow, by moving from the respective rest position (as shown for example in Figures 2 and 3), this sheet-like component S to slide towards the hollow housing 20, thus substantially downwards, during bending. The tilting support means 22, 24 are also provided with contrast elastic components 30, 32 for the support means 22, 24 return to their rest position following each single bending operation.

According to the invention, each tilting support means 22, 24 is rotatably mounted onto at least one respective rotation pin 26, 28 which is formed integrally with the end edge of a respective side wall 16, 18, extends along the longitudinal direction L and has a substantially cross-sectional circular convex profile. In other words, each rotation pin 26, 28 is a cylindrical pin. The rotation of the tilting support means 22, 24, which takes place on the respective cylindrical rotation pins 26, 28 instead of inside concave seats, as is the case with the bending dies according to the prior art, makes it possible to form particularly small (acute) bending angles of the sheet-like components S, up to a minimum of 30° and less (see for example Figure 3). Furthermore, the presence of the contrast elastic components 30, 32 provides that the tilting support means 22, 24 return to their starting or rest position and helps facilitating extraction and handling of the bent sheet-like components S.

According to a particularly advantageous aspect of the present invention, the contrast elastic components 30, 32 comprise at least one presser 30, which is at least partially inserted inside the hollow housing 20 and is provided with at least one contact surface 34, 36 which engages with a corresponding contact surface 38, 40 of a respective tilting support means 22, 24. The contrast elastic components 30, 32 also comprise one or more elastic elements 32, which are sandwiched between the base portion 14 of the main body 12 and the presser 30 and operate by compression for pushing the contact surfaces 34, 36 of the presser 30 against the corresponding contact surfaces 38, 40 of the tilting support means 22, 24. The presser 30, thanks to its elastic elements 32, therefore provides that the tilting support means 22, 24 return to their starting or rest position and reduces their friction on the respective rotation pins 26, 28.

As shown in the figures, each tilting support means 22, 24 preferably comprises at least one substantially flat support surface 42, 44, which extends along the longitudinal direction L and is adapted to receive and support the sheetlike components S to be bent. Each contact surface 38, 40 of a single tilting support means 22, 24 also extends along the longitudinal direction L and joins with the respective support surface 42, 44 according to an acute angle. In other words, each tilting support means 22, 24 is preferably wedge- shaped and its interaction with the presser 30 and the respective elastic elements 32 helps drawing sheet-like components S with particularly small bending angles (up to 30° and less) and also with medium/high thicknesses from the bending die.

Each elastic element 32 preferably consists of a spiral spring working along the axis X which is substantially orthogonal to the longitudinal direction L. This type of contrast elastic components 30, 32 (presser 30 plus springs 32), for the same length in the longitudinal direction L of the bending die 10, makes it possible to reduce the overall number of springs with respect to the bending dies according to the prior art, consequently also reducing the overall size of the bending die 10.

The bending die 10 can be manufactured with variable lengths according to specific needs and the various types of press brakes. For example, for lengths up to 500 mm, the bending die 10 can be manufactured by wire EDM technology, while for lengths greater than 500 mm, the bending die 10 can be manufactured by mechanical machining with chip removal, with suitable dimensional variations due to the tools used.

The tilting support means 22, 24 and/or the respective rotation pins 26, 28 can extend continuously along the entire length, measured along the longitudinal direction L, of the main body 12 of the bending die 10. Alternatively, the tilting support means 22, 24 and/or the respective rotation pins 26, 28 could instead extend discontinuously along the longitudinal direction L of the main body 12 of the bending die 10.

According to the first embodiment of the bending die 10, shown in Figures 1 to 4, the main body 12 of such bending die 10 comprises at least one projection 46 which extends starting from the base portion 14, in a direction opposite to the side walls 16, 18 (thus downwards), and extends along the longitudinal direction L. This projection 46 makes it possible, in a per se known manner, to connect the bending die 10 to the press brake.

On the other hand, according to the second embodiment of the bending die 10, shown in Figure 5, the main body 12 of such bending die 10 comprises at least one cavity 48 which extends starting from the base portion 14, in the direction opposite to the hollow housing 20 (thus downwards), and extends along the longitudinal direction L. This cavity 48 is sized and shaped in such a way as to make it possible to connect the bending die 10 with a corresponding bending die, or with another tool suitable for connection, which is already present on the press brake.

It has thus been seen that the bending die for a press brake according to the present invention achieves the previously highlighted objects. The bending die according to the present invention makes it possible to bend sheet-like sheet metal components by means of the downward rotation of opposite tilting support means, contrasted by a spring-loaded presser which provides that the tilting support means return to their starting position and reduces their friction on the respective cylindrical rotation pins. Thanks to its particular shape and combination of elements, the bending die according to the present invention thus makes it possible to provide bending angles less than or equal to 30° on any type of sheet metal, of any thickness and with any type of press brake punch. Sliding marks on the sheet metal are reduced during bending compared to the bending dies according to the prior art. The bending press according to the present invention makes it possible to obtain reduced bending edges, reduces the deformation of the holes on the bending line or near it and also reduces the possibility of scratching the embossed metal sheets.

The bending press for a press stroke according to the present invention thus conceived is however susceptible of numerous modifications and variations, all of which falling within the scope of the same inventive concept; furthermore, all the details can be replaced by technically equivalent elements. In practice, the materials used, as well as the shapes and dimensions, may be any according to the technical requirements.

The scope of protection of the invention is therefore defined by the attached claims.