DEVICE FOR CRUSHING THE ENDS OF TUBULAR SECTIONS, IN PARTICULAR OF VEHICULAR BUMPERS, AND RELATED METHOD FOR PROVIDING SAID CRUSHING

DESCRIPTION

The present invention relates to a device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle, according to the preamble of claim 1. The present invention also relates to a method for providing said crushing. Tubular sections, in particular made from metal material, are commonly used in the art for protecting a vehicle body from accidental collisions, e.g. when parking the vehicle or caused by other moving vehicles.

The solutions adopted so far are in general a compromise between two strong needs. On the one hand, in fact, the bumper structure must be sufficiently stiff and solid to properly protect not only the body of the vehicle, but also its occupants. On the other hand, there is a tendency to reduce the weight of body parts, including bumpers, in order to reduce their effect on engine power and thus fuel consumption.

The latest metal tubular sections used as bumpers offer great advantages in terms of vehicle and occupant protection, production costs, weight, and possibility of being shaped in accordance with the stylistic and aerodynamic requirements of the vehicle on which they are to be installed.

It is however necessary to solve the problem of providing a structure which can dissipate the kinetic energy generated by the collision, thus avoiding rebound effects. Bumpers known in the art are therefore manufactured by using metal sections having corrugated portions which allow to increase flexural rigidity while at the same time absorbing shocks properly.

Said corrugated portions allow the metal section to act substantially as a "shock absorber" element.

United States patent No. US 5,577,796 describes a vehicular bumper, in particular the ends thereof, having corrugated portions. Said ends have a smaller cross-section than the bumper central portion, in that they are subjected to side pressure by conventional pressure means, which crash said ends thus forming the corrugated portions on the crushed walls. The bumper

ends are then bent by suitable bending means in order to follow the profile of the vehicle on which they are to be installed and to meet the stylistic and aerodynamic requirements thereof. Crushing the bumper ends through pressure means known in the art has many drawbacks. In particular, known pressure means prevents a proper and even pressure to be applied to the walls of the metal section, resulting in the risk of two adjacent corrugations of the same corrugated wall touching each other, thus weakening the whole structure. In order that the corrugated portions of the metal section can act as a shock absorber element, the geometry thereof must be preserved, in particular by keeping an adequate distance between two adjacent corrugations of the corrugated wall, so that they cannot touch each other. hi fact, any contact between the corrugated walls of the metal section would weaken the structure of the wall itself, which may fail due to excessive bending, thus inevitably reducing the efficiency of the bumper; also, such contact would decrease the elasticity of the corrugated wall and, consequently, its shock-absorbing capability. In this frame, it is the main object of the present invention to overcome the above-mentioned drawbacks by providing a device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle, which allows to obtain the corrugated portions of the metal section in such a manner that their geometry is preserved, in particular even after said crushing has taken place. It is a further object of the present invention to provide a device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle, which allows to keep an appropriate distance between two adjacent corrugations of the corrugated wall of said tubular section, so that no contact occurs between said corrugations and that the structural integrity and the shock-absorbing capability of the corrugated wall are preserved. These objects are achieved according to the present invention through a device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle, and a method for providing said crushing which incorporate the features set out in the appended claims, the latter being 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:

Fig. 1 is a perspective view of the crushing device according to the present invention;

Figs. 2a and 2b are perspective views of a tubular section, respectively before and after being crushed by the device according to the present invention;

Fig. 3 is a sectional view of the device and of the tubular section according to the present invention; - Figs. 4a and 4b show a front view and a sectional view, respectively, of a variant of the crushing device according to the present invention.

Referring to Figs. 1 to 3, reference numeral 10 designates a device for crushing at least an end portion 21 of a tubular section 20, in particular a bumper of a vehicle.

According to the present invention, said device 10 comprises a substantially tapered cavity 11 adapted to house the end portion 21 of the tubular section 20 and to crush it as said end portion 21 is progressively inserted into said cavity 11.

In particular, Fig. 3 shows that said cavity 11 comprises a mouth 12 having a larger longitudinal section than an end part 13 of said cavity 11.

The particular shape of the cavity 11 allows the end portion 21 to be crushed; in fact, as the tubular section 20 is progressively inserted into said cavity 11, the inner walls of the cavity 11 will exert increasing pressure on the outer walls of the end portion 21, which will thus be crushed in adaptation to the dimensions of the cavity 11.

Said cavity 11 also comprises a plurality of ribs 14 which in proximity to said mouth 12 have a shape being substantially complementary to corrugations 22 of said tubular section 20. As shown in Fig. 3, the distance between said ribs 14 is progressively reduced toward said end part 13 of said cavity 11.

It is therefore apparent that the ribs 14 allow to accomplish the crushing of the end portion 21 in such a manner that the geometry of the tubular section 20 is preserved, in particular by keeping an appropriate distance between adjacent corrugations 22 of said tubular section 20 and by preventing said corrugations from collapsing onto one another.

This allows to keep the efficiency and the shock-absorbing capability of the bumper unchanged even once the end portion 21 of the tubular section 20 has been crushed; as a matter of fact, this method prevents the corrugations 22 of the metal section from touching one another, thereby avoiding any contact that could otherwise weaken the structure of the corrugated walls, which would inevitably lose elasticity.

Referring again to Fig. 1, the device 10 preferably comprises a first half shell 1OA and a second half shell 1OB, which can be separated in order to extract the tubular section 20 once

the end portion 21 thereof has been crushed, without damaging said end portion 21. Figs. 4a and 4b show a possible variant of the device 10 according to the present invention. These figures clearly show that, within the cavity 11, the device 10 comprises a core 15 having a shape which is substantially complementary to but slightly smaller than that of the cavity 11. As a result, between the outer surface of the core 15 and the walls of the cavity 11, the device 10 comprises a gap 16 wherein the end portion 21 of the tubular section 20 can be inserted during the crushing process.

It is apparent that the presence of the core 15 allows to support the end portion 21 of the tubular section 20 from the inside during the crushing operations, thus further improving the control of the crushing geometry and preventing said end portion 21 from collapsing.

The device 10 for crushing at least an end portion 21 of the tubular section 20 may also be used as a vice in order to bend and stretch the tubular section 20, in particular so that the tubular section 20 can follow the profile of the vehicle on which it will be installed, thus meeting the stylistic and aerodynamic requirements of that particular vehicle. Advantageously, this allows to accomplish a substantially simultaneous bending of the section 20 while crushing the end portion 21 by using the same equipment.

In particular, the crushing of the end portion 21 of the tubular section 20, in particular a bumper of a vehicle, according to the present invention is accomplished as follows: said end portion 21 is inserted into a mouth 12 of a cavity 11 of a device 10, said cavity 11 being substantially tapered; a reciprocal motion is induced between said tubular section 20 and the device 10, until said end portion 21 reaches an end part 13 of said cavity 11, so that the inner walls of the cavity 11 exert increasing pressure on the outer walls of the end portion 21, which are thus crushed in adaptation to the dimensions of the cavity 11. The above method for crushing the end portion 21 also includes a step for keeping an appropriate distance between adjacent corrugations 22 of said tubular section 20 through the insertion of a plurality of ribs 14 between said corrugations 22, said ribs being obtained on the walls of said cavity 11 and being arranged at a progressively decreasing distance toward said end part 13 of said cavity 11. The process for crushing the end portion 21 according to the present invention may also include an additional step for separating a first half shell 1OA from a second half shell 1OB of said device 10, so that the tubular section 20 can be removed after its end portion 21 has been

crushed without damaging said end portion 21.

Additionally, the process for crushing the end portion 21 of the tubular section 20 according to the present invention may also include a step for supporting said end portion 21 from within the cavity 11 during the crushing operations, in particular by means of a core 15 located inside the cavity 11 and having a shape which is substantially complementary to but slightly smaller than that of the cavity 11.

The reciprocal motion between said tubular section 20 and the device 10 preferably takes place through the activation of a hydraulic cylinder, not shown in the drawings, which causes the device 10 to move forward relative to the tubular section 20. The process may also include a step for bending the tubular section 20 by using the device 10 for crushing at least an end portion 21 of the tubular section 20 as a vice, thus accomplishing simultaneous bending and crushing through the same equipment.

It is also clear that the above steps for crushing and/or bending the end portion 21 of the tubular section 20 according to the present invention may be handled by a control system, in particular an electronic, programmable and/or preselectable one, electrically and/or mechanically connected to the device 10.

The advantages of a method and a device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle, according to the present invention are apparent from the above description. In particular, such advantages are due to the fact that the device 10 according to the present invention allows a proper and even pressure to be applied to the walls of the metal section 20, while at the same time forming the corrugated portions of the metal section in such a manner that the their geometry is preserved. Furthermore, using the device 10 according to the present invention allows to keep an appropriate distance between two adjacent corrugations of the corrugated wall of said tubular section, so that they cannot touch each other. This allows to keep the efficiency and the shock- absorbing capability of the bumper unchanged even once the end portion 21 of the tubular section 20 has been crushed, in that the structure of said tubular section 20 is not weakened by any contact between the corrugations 22 and, consequently, the original elasticity of the corrugated wall is preserved.

It is plain that the present invention is non limited to the above-described method and device for crushing at least an end portion of a tubular section, in particular a bumper of a vehicle,

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 appended claims.

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