APPARATUS FOR BENDING AND STRETCHING SECTIONS MADE OF HIGH- STRENGTH MATERIAL, IN PARTICULAR IRON OR STEEL VEHICULAR BUMPERS, AND RELATED METHOD FOR BENDING AND STRETCHING SAID SECTIONS

DESCRIPTION

The present invention relates to an apparatus for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, according to the preamble of claim 1.

The present invention also relates to an associated method for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers.

Apparatus for bending and stretching sections are known in the art, in particular for manufacturing vehicular bumpers; said apparatus are generally known as "stretch and bend machines".

In these apparatus, both ends of the section are inserted into two jaws, which typically have an arched or a "C" shape, and are then locked in said jaws. Subsequently, each end of the section is laid down on a forming die having a substantially first straight portion and a second rounded portion; said section ends are bent by the rotation of said forming dies and the pulling action of the jaws.

An apparatus of the above-described type has been disclosed in US patent No. US 3,832,879; in particular, said US patent describes an apparatus comprising: a pair of jaws, each jaw being adapted to receive the ends of a section; a pair of forming dies, each forming die comprising a first substantially straight portion and a second rounded portion and being coupled to one of said jaws for the purpose of bending said section ends; - moving means for operating the movable parts of the apparatus, in particular said pair of jaws and said pair of forming dies.

In particular, in the apparatus described in said US patent, the section ends are inserted into jaws having an open shape, i.e. essentially a "C" cross-section. The surface of the section is then laid down against the pair of forming dies, in particular through the rotation of said forming dies and the simultaneous pulling action of the pair of jaws. As a consequence, the shape of the central portion of the section remains substantially straight and matches the shape of the first portion of each forming die, whereas the section ends are bent through the

combined action exerted by the forming die and by the moving jaws, so that the bending shape attained substantially corresponds to the outer surface of the second portion of each forming die.

The open-shaped jaws, typically having a "C" cross-section, according to the aforementioned US patent application allow the section to be easily loaded into and unloaded from said jaws. In particular, all the user has to do in order to load the section is inserting the section ends into the "C" cross-section of the jaws; on the contrary, all that is needed in order to unload the section is pulling out the section ends from the "C" cross-section of the jaws. It has however been noticed that the shape of the jaws according to the aforementioned US patent application can only be used in those cases wherein the section to be machined is made of a material easy to bend, in particular thin low-strength steel. Nevertheless, the section to be machined is often made of high-strength material, in particular iron or steel, i.e. a particularly hard, strong and thick material. In such cases, the jaws are subjected to considerable stress when clamping the section ends, and open jaws having a "C" cross-section cannot clamp said section ends properly; it follows that such jaws cannot ensure adequate clamping forces on the section itself.

Apparatus are also known in the art which are adapted to bend and stretch sections made of high-strength material and having high structural rigidity, in particular for the purpose of manufacturing vehicular bumpers. Said apparatus comprise jaws provided in one single unit block; also, said jaws have cavities into which the ends of the section to be bent are inserted. However, these apparatus also suffer from serious drawbacks, which are mostly due to the difficulties to be faced by the user when loading the section into the jaw cavities and when unloading the section once it has been bent by the apparatus. In this frame, it is the main object of the present invention to overcome the above-mentioned drawbacks by providing an apparatus for bending and stretching sections made of high- strength material, in particular iron or steel vehicular bumpers, which can provide optimal clamping of the ends of the section to be bent and which can ensure adequate clamping forces on the section, in particular when said section has high structural rigidity. It is a further object of the present invention to provide an apparatus for bending and stretching high-strength sections, in particular iron or steel vehicular bumpers, which is so conceived as to allow the section to be easily loaded and then unloaded once it has been bent by the apparatus. Said objects are achieved by the present invention through an apparatus for bending and

stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, and a related method for bending and stretching said sections incorporating the features set out in the appended claims, which are intended as an integral part of the present description. Further objects, features and advantages of the present invention will become apparent from the following detailed description and from the annexed drawings, which are supplied by way of non-limiting example, wherein:

Figs. Ia to Id are schematic top views showing the different operation steps of an apparatus for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, according to the present invention;

Figs. 2a to 2c are schematic top views showing the different operation steps of a second embodiment of an apparatus for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, according to the present invention.

Referring now to Figs. Ia to Id, reference number 10 designates as a whole an apparatus for bending and stretching a section 20 made of high-strength material, in particular an iron or steel vehicular bumper, according to the present invention.

Apparatus 10 comprises a first jaw 31 and a second jaw 32 provided as one single unit block; each of said first jaw 31 and second jaw 32 comprises a cavity 33A, 33B adapted to receive a first end 21 and a second end 22 of said section 20. Apparatus 10 also comprises a first forming die 41 and a second forming die 42 adapted to be coupled to said first jaw 31 and second jaw 32, respectively, for the purpose of bending said first end 21 and second end 22 of section 20.

Apparatus 10 additionally comprises moving means (not shown in the drawings) for operating the movable parts of apparatus 10, in particular said jaws 31, 32 and said forming dies 41, 42. In accordance with the present invention, apparatus 10 comprises actuator means which allow said first end 21 and second end 22 to be loaded into cavities 33 A, 33B, and which allow said first end 21 and second end 22 to be unloaded from cavities 33 A, 33B once said section 20 has been bent by said jaws 31, 32 and said forming dies 41, 42.

Preferably, said actuator means comprise a first element 51 and a second element 52, said first element 51 and second element 52 being preferably coupled to said first forming die 41 and second forming die 42, respectively.

In particular, said first element 51 and second element 52 comprise each a supporting portion

53A, 53B having a shape adapted to be coupled to at least a portion of section 20. Said

supporting portions 53A, 53B allow a section 20 to be placed on said actuator means, thus allowing jaws 31, 32 to approach the section and said first end 21 and second end 22 of the section 20 to be loaded into the cavities 33A, 33B.

Said actuator means additionally comprise a mechanism 54, in particular a pneumatic one, for moving said first element 51 and second element 52.

Figs. Ic and Id respectively show a step of bending and stretching the section 20 (Fig. Ic) and a step of unloading the bent section 20 (Fig. Id). In particular, Fig. Id schematically shows the sequence for unloading section 20 from apparatus 10, wherein the thinner lines indicate the beginning of the step of unloading section 10, whereas the bold lines indicate the last part of said unloading step.

By comparing Fig. Ic with Fig. Id, it can be seen that said first element 51 and second element 52 allow to exert a thrust of intensity Y for unloading bent section 20, said thrust of intensity Y being proportional to a latitudinal displacement X of said first jaw 31 and second jaw 32. In particular, the proportionality between said thrust of intensity Y and said latitudinal displacement X is a function of an angle β of rotation of the assembly consisting of jaws 31, 32 and forming dies 41, 42 with respect to a substantially horizontal plane A, said rotation being carried out in order to bend said first end 21 and second end 22 of section 20. It follows then that Y = f(X, β). It can be deduced from the above description that, in order to unload section 20 as in the example of Figs. Ic and Id, said first element 51 and second element 52 exert a thrust of intensity Y which is equal to:

Y = X tg β.

Figs. 2a to 2c are schematic top views showing the different operation steps of a second embodiment of the apparatus for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, according to the present invention. In particular, Fig. 2a refers to a step of loading section 20 into cavities 33 A, 33B of apparatus 10, whereas Figs. 2b and 2c refer to a step of unloading bent section 20. In Figs. 2b and 2c as well, the thinner lines indicate the beginning of the step of unloading section 10, whereas the bold lines indicate the last part of said unloading step. It can be seen in Figs. 2a-2c that said first element 51 and second element 52 respectively comprise a first hooking portion 55 and a second hooking portion 56 adapted to interfere with an outer surface of section 20; essentially, said first hooking portion 55 and second hooking portion 56 allow section 20 to be clamped onto supporting portion 53A, 53B of said first

element 51 and second element 52.

Said clamping of section 20 onto supporting portions 53A, 53B facilitates the task of loading section 20 into cavities 33A, 33B.

In particular, the actuation of second hooking portion 56 as first jaw 31 is approaching allows first end 21 of section 20 to abut against a first limit stop surface 34 of cavity 33 A of first jaw 31; vice versa, the actuation of first hooking portion 55 as second jaw 32 is approaching allows second end 22 of section 20 to abut against a second limit stop surface 35 of cavity 33B of second jaw 32. However, the user of apparatus 10 according to the present invention may decide to reverse the order of these operations, i.e. to begin by actuating first hooking portion 55 and approaching second jaw 32, and then to actuate second hooking portion 56 and approach first jaw 31.

It is clear that the aforementioned operations allow the user to choose either end 21 or 22 as a reference for loading section 20 before starting the bending process. In fact, the length of normal production sections 20 is not always exactly the same, but oscillates within a certain tolerance; consequently, it is particularly advantageous that all the various operating steps of apparatus 10 (just like any production stages related to section 20, such as bending, cutting, forming, etc.) use the same reference, e.g. either one of ends 21 or 22 of section 20. Likewise, locking section 20 onto supporting portions 53A, 53B facilitates the task of unloading said first end 21 and second end 22 of section 20 from cavities 33 A, 33B of first jaw 31 and second jaw 32. In particular, the actuation of second hooking portion 56 and the latitudinal displacement X of first jaw 31 allows first end 21 to come out of cavity 33 A of the first jaw 31 ; vice versa, the actuation of first hooking portion 55 and the latitudinal displacement X of second jaw 32 allows second end 22 to come out of cavity 33B of second jaw 32. It is apparent that said first hooking portion 55 and second hooking portion 56 allow to overcome any friction between said first end 21 and second end 22 of section 20 and the inner walls of cavities 33A, 33B of jaws 31, 32; consequently, this facilitates the operations for loading section 20 into cavities 33 A, 33 B as well as the operations for unloading said first end 21 and second end 22 of section 20 from cavities 33 A, 33B of first jaw 31 and second jaw 32. Below is described a method for bending and stretching a section 20 made of high-strength material, in particular an iron or steel vehicular bumper, which uses an apparatus 10 comprising: a first jaw 31 and a second jaw 32 provided as one single unit block, each of said first

jaw 31 and second jaw 32 comprising a cavity 33 A, 33B adapted to receive a first end 21 and a second end 22 of said section 20, respectively; a first forming die 41 and a second forming die 42 adapted to be coupled to said first jaw 31 and second jaw 32, respectively, thus forming an assembly which allows to bend said first end 21 and second end 22 of section 20; moving means for operating the movable parts of apparatus 10, in particular said first jaw 31 and second jaw 32 and said first forming die 41 and second forming die 42. According to the present invention, said method comprises the following steps:

A) positioning said section 20 onto actuator means comprising a first element 51 and a second element 52, each having a respective supporting portion 53 A, 53B (see Fig. Ia);

B) activating said moving means in order to approach said first jaw 31 and second jaw 32, thus loading said first end 21 and second end 22 of the section 20 into cavities 33A, 33B (see Fig. Ib);

C) activating said moving means in order to couple said first forming die 41 and second forming die 42 to section 20 and to move the assembly consisting of the jaws 31, 32 and the forming dies 41, 42 by an angle of rotation β for bending said first end 21 and second end 22 (see Fig. Ic);

D) activating said first element 51 and second element 52 in order to exert a thrust of intensity Y for unloading the section 20 once it has been bent (see Fig. Id). In accordance with the present invention, said step D) of activating said first element 51 and second element 52 is carried out in such a way that said thrust of intensity Y is proportional to a latitudinal displacement X of said first jaw 31 and second jaw 32.

Preferably, said step D) of activating said first element 51 and second element 52 is carried out in such a way that said thrust of intensity Y and said latitudinal displacement X are a function of said angle of rotation β. In particular, said step D) of activating said first element

51 and second element 52 is adapted to produce a thrust of intensity Y equal to:

Y = X tg β where X is the latitudinal displacement of the assembly consisting of jaws 31, 32 and forming dies 41, 42, and β is the angle of rotation of the assembly consisting of jaws 31, 32 and forming die 41, 42 with respect to a substantially horizontal plane A, said rotation being carried out by the assembly consisting of jaws 31, 32 and forming dies 41, 42 in order to bend said first end 21 and second end 22 of section 20.

Preferably, said step D) of activating said first element 51 and second element 52 is carried

out by activating a mechanism 54, in particular a pneumatic one, of said apparatus 10, said mechanism 54 being coupled to said first forming die 41 and second forming die 42.

Said step B) of activating said moving means may be carried out in such a way as to include the additional steps of: - actuating a second hooking portion 56 of said second element 52, thus causing section

20 to be clamped onto supporting portion 53 A of first element 51; approaching said first jaw 31, so that said first end 21 of section 20 abuts against a first limit stop surface 34 of cavity 33 A of said first jaw 31 ; releasing said second hooking portion 56 in order to unclamp section 20 from supporting portion 53A of first element 51 ; approaching said second jaw 32 in order to insert said second end 22 of section 20 into cavity 33B of second jaw 32.

In this case as well, the user of apparatus 10 according to the present invention may decide to reverse the above operations, i.e. to begin by actuating first hooking portion 55 and approaching second jaw 32, and then to proceed by actuating second hooking portion 56 and approaching first jaw 31. As aforementioned, the step of actuating a hooking portion 55, 56 and approaching jaw 31, 32 on the opposite side allows to determine which end 21, 22 of section 20 should be used as a loading reference before starting the bending process; this is done in order to adapt the section bending process to possible tolerances and to choose a single reference (in particular either end 21, 22 of section 20) for all of the various production stages.

Furthermore, said step D) of activating said first element 51 and second element 52 in order to unload the section 20 may include the following alternate steps (shown schematically in Figs.

2b and 2c): - actuating a second hooking portion 56 of second element 52 in order to clamp section

20 onto said second element 52 while simultaneously determining a latitudinal displacement

X of said first jaw 31 ; actuating a first hooking portion 55 of first element 51 in order to clamp section 20 onto said first element 51 while simultaneously determining a latitudinal displacement X of said second j aw 32.

Preferably, said alternate steps are repeated for a predetermined number of times.

It is clear that said alternate steps allow first end 21 and second end 22 of section 20 to come out of cavities 33 A, 33B of first jaw 31 and second jaw 32, thus causing section 20 to be

unloaded from apparatus 10.

Preferably, said alternate steps of actuating said first hooking portion 55 and second hooking portion 56 are carried out in such a way as to obtain a thrust of intensity Y proportional to a latitudinal displacement X of said first jaw 31 and second jaw 32 as a function of an angle of rotation β of the assembly consisting of jaws 31, 32 and forming dies 41, 42 with respect to a substantially horizontal plane A.

The advantages of an apparatus for bending and stretching sections made of high-strength material, in particular iron or steel vehicular bumpers, and of a related method for bending and stretching sections made of high-strength material according to the present invention are apparent from the above description.

In particular, these advantages consist in the fact that the apparatus for bending and stretching sections made of high-strength material according to the present invention can provide optimal clamping of said ends of the section to be bent, and that it can ensure adequate clamping forces on the section, in particular when the sections used have high structural rigidity.

Another advantage offered by the apparatus according to the invention is that it allows the section to be properly loaded and then easily unloaded once it has been bent by the apparatus. In particular, the actuator means included in the apparatus according to the present invention allow the section ends to be easily loaded into the cavities of jaws provided in one single unit block. In addition, the actuator means according to the present invention make it easy to unload the bent section, in that they allow to exert a thrust proportional to a latitudinal displacement of the jaws as a function of an angle of rotation of the assembly consisting of the jaws and the forming dies. An additional advantage of the apparatus according to the present invention is that the operations of loading and unloading the section are further facilitated by the fact that the actuator means are provided with hooking portions; in particular, said hooking portions interfere with an outer surface of the section, thus clamping the latter onto said actuator means. This clamping action is particularly advantageous because it allows the section to be positioned properly during the loading operations, i.e. by using either section end as a uni vocal reference, and because it allows to surmount any friction between the section ends and the inner walls of the jaw cavities, thereby facilitating the section unloading operations as well. The apparatus and method described herein by way of example may be subject to many

possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements. For example, among many variations, said jaws 31, 32 and forming dies 41, 42 may be so provided as to form a single element.

According to a further variant, said actuator means may be so provided as to have a single element 51; said single element 51 may even not be coupled to said jaws 31, 32 and/or said forming dies 41, 42.

It can therefore be easily understood that the present invention is not limited to the above- described apparatus and method, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.

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