Patent Application
20150090850
The present invention concerns a segment of an articulated arm, for example, but not exclusively, of the type which can be installed on pumps transported on trucks for the distribution of concrete. In particular, the segment according to the present invention is made of composite material, such as carbon, aramidic or glass fibers or similar, drowned in a binding resin.
The present invention also concerns the articulated arm which comprises at least one segment of said type.
Segments for articulated arms are known, made of metal material, which are reciprocally hinged at the respective ends and to which actuation members are associated, for example by means of brackets.
The actuation members provide to articulate one segment with respect to the other, to take them into at least a first extended or working configuration, in which they reach a desired operating position, and a second folded configuration in which the segments are folded one with respect to the other to assume a condition of minimum bulk, usually in the transport condition.
It is also known that, to reduce the overall weight of the articulated arms, the segments are made of composite material, for example comprising carbon, glass or aramidic fibers or similar, which are drowned in a binding resin.
It is also known that, when the articulated arms are in use, the segments are subjected to great stresses and vibrations and it is therefore necessary to correctly size and configure the sections of the individual segments so as to satisfy the requirements of safety and mechanical resistance.
In particular, it is known that the most stressed zones are the reciprocal hinging points between the individual segments, and also the zones where the actuation members are pivoted.
It is known that, with regard to segments made of metal material, the attachment zones are obtained by attaching, usually by welding, to the longitudinal body of the segment, one or more flanges provided with holes in which the actuation members are pivoted. In known solutions of segments made of composite material, it is known to provide that this zone is always made of metal material. In this case, solutions are known which provide to make of metal material a tract of the longitudinal body of the segment, which tract is subsequently incorporated during the step of making the segment of composite material. Said tract of metal material is in turn provided with attachment zones for the actuation members, for example consisting of brackets welded thereto.
One disadvantage of known segments is that they require a rather complex manufacturing process, and are thus costly and have too high overall weights.
Another disadvantage of known segments is that the position of the attachment zone of the actuation member, with respect to the point where it pivots with the subsequent segment, is not correlated to the mechanical resistance of the segment itself, to the size of the actuation member used and to the safety margins required. This entails the need to use actuation members with sizes that are not appropriate for the particular application on the articulated arm, and also the need to oversize the sections of particular portions of the segment, thus increasing its overall weight.
Furthermore, when they are closed on themselves, known articulated arms have a very large overall bulk, with the disadvantage that it is less easy to move and maneuver the vehicle on which the articulated arm is mounted.
U.S. Pat. No. 5,316,709 discloses an arm for an excavator comprising an articulated segment in which there are two attachment zones, the first to the segment connected to the vehicle, the second to attach the actuator that drives the excavation element. The two attachment zones are substantially at the same height in correspondence with two protruding parts of the profile of the articulated segment, which has a section shape like a double triangle with coinciding bases.
The section shape described in US'709 is not suitable to solve the disadvantages indicated above, in particular the resistance to point-by-point stresses deriving from the drive of the actuators and the reduction in bulk during the transfer and movement of the vehicle.
One purpose of the present invention is to obtain a segment of an articulated arm which is simple to make, economical and which has a lower overall weight than known segments.
Another purpose is to obtain a segment of an articulated arm that is optimized in relation to mechanical resistance, to the size of the actuation member used and to safety requirements.
Another purpose of the present invention is to obtain an articulated arm comprising at least a segment of the above type in which its overall mechanical resistance and its overall size is optimized, at least in the transport configuration.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.
In accordance with the above purposes, a segment of an articulated arm is made of composite material, such as for example comprising carbon, glass or aramidic fibers or similar, made solid to each other using resins, and is applied principally, but not exclusively, on articulated arms used for the distribution of concrete.
The segment according to the present invention has an elongated shape which defines a longitudinal axis. The segment also has a box-like cross section and comprises at least a first end portion configured to allow the pivoting of a further segment, and a second intermediate portion configured to allow the pivoting of an actuation member, such as a hydraulic actuator for example, a pneumatic actuator, a screw-type jack or other. The articulated segment also has a third end portion to which further segments of the type according to the present invention or different types can be pivoted.
In accordance with one feature of the present invention, the first end portion and the second intermediate portion are made in a single body with each other, and the second intermediate portion comprises a zone protruding transverse to the longitudinal axis, defined at least by a first side and a second side converging with respect to each other and defining a vertex, advantageously rounded or with a rounded connection. First pivoting elements, for example first pivoting seatings, are made in said protruding zone, which allow to pivot the actuation member.
The two converging sides are filleted to adjacent tracts, substantially rectilinear and substantially parallel to the longitudinal axis of the segment, which define the parts of the segment adjacent to the protruding zone.
Thanks to this geometrical configuration of the segment, the actuation member, pivoted between the second intermediate portion and an articulated element associated with the first end portion, at least when the arms are in a closed position is disposed parallel to the rectilinear tract adjacent to the protruding zone in a position completely contained in the bulk of the segment itself.
In this way it is possible to obtain a segment completely in a single body that integrates the attachment zone of the actuation member and that is achieved during the same step of obtaining the rest of the segment, and with the same material.
The segment according to the present invention, and in particular the first end portion and the second intermediate portion, is defined by at least an intrados surface and an extrados surface. According to the invention, the protruding zone is obtained on the side of the intrados surface.
According to another feature of the invention, the first pivoting elements are disposed/integrated protruding with respect to the intrados surface of the cross section of the first end portion.
This particular disposition of the pivoting elements allows to optimize the positioning of the actuation member which, when the articulated arm is in its closed condition, is disposed so as to prevent conditions of interference with the other segments, with the advantage of overall compactness of the articulated arm.
According to another feature of the invention, in the intrados surface, and in correspondence with the first side of the protruding zone, at least a through cavity is made, to allow the actuation member to be inserted through it.
The protruding zone of the second intermediate portion also has a closed box-like cross section. The actuation member is therefore inserted through the through cavity to allow it to be subsequently pivoted. At least one end tract of the actuation member is therefore positioned inside the box-like section of the segment.
According to another feature of the present invention, the second side that defines the protruding zone and that is filleted to the rectilinear tract between the protruding zone and the third end portion, is inclined with respect to the longitudinal axis by an angle comprised between 5° and 25°, preferably between 10° and 20°. This angle, of a reduced value, defines a very gentle connection between the protruding zone and the adjacent rectilinear tract, and allows to obtain a good compromise between mechanical resistance of the segment and quantity of material that is used to make the latter. Too great an amplitude determines very high shearing effects in said zone, which are damaging for the purposes of the mechanical resistance; vice versa, lower amplitudes entail using a considerable quantity of material to make the segment, with consequent bigger overall sizes which not only increase the overall weight of the segment but also determine problems in closing the articulated arm which comprises said segment.
Between the second side defining the protruding zone and the third end portion there is advantageously a filleted tract that allows to confer greater mechanical resistance on the segment.
According to another form of embodiment, the second side defining the protruding zone and the filleted tract develop overall for a determinate first length of the second intermediate portion, and in particular Applicant has calculated that an optimum ratio between the rounding radius of the filleted tract and the first length is comprised between 1.8 and 7.2, preferably greater than 3.5.
According to another feature of the invention, the first side of the protruding zone, which connects the vertex of the protruding zone with the rectilinear tract of the first end portion is inclined with respect to the longitudinal axis by an angle comprised between 25° and 50°, preferably between 30° and 45°, even more preferably between 35° and 40°. Said angle, having a greater value than the angle between the second side of the protruding zone and the third end portion, as we said, allows to house the actuation member completely inside the through cavity, however preventing the actuation member from being completely enclosed inside the body of the segment. Indeed, too limited an amplitude of the angle would also reduce the possibility of movement of the actuation member, while too great an amplitude would be disadvantageous in terms of mechanical resistance of the segment, and irreconcilable with the requirements of production with the composite materials described above.
According to another form of embodiment, the first end portion is provided with at least second pivoting elements, or second pivoting seatings, configured to allow the connection of articulation elements between the actuation member and another segment.
According to some forms of embodiment, the first pivoting elements and the second pivoting elements are distanced from each other by a determinate axial distance, measured substantially parallel to the longitudinal axis, and by a determinate transverse distance. The ratio between the axial distance and the transverse distance is comprised between 3.9 and 15.6, preferably between 4.5 and 12, even more preferably between 6 and 10. This particular disposition allows to optimize the positioning of the actuation member that is associated with the segment, and also allows to limit problems of interference during the closing of the articulated arm.
According to other forms of embodiment, the first and/or the second pivoting elements comprise, integrated respectively in the first end portion and the second intermediate portion of the segment, metal inserts such as bushings, attachments or whatever else is needed to allow the pivoting of the actuation member or of brackets.
According to some preferential forms of embodiment, it may be provided that the portions disposed respectively on one side and the other of the protruding zone of the second intermediate portion have a substantially one-directional disposition of the fibers, that is, parallel to the longitudinal direction of the segment. On the contrary, the protruding zone can have a disposition of the fibers suitably modified and such as to optimize the properties of mechanical resistance required in said zone.
The present invention also concerns an articulated arm that comprises at least one segment as described above.
These and other characteristics of the present invention will become apparent from the following description of one form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:
To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings.
With reference to
The segments 10, 15 are made of composite material, that is, carbon, glass aramid or other fibers, made solid with each other by resins.
The segment 10 has a rectangular section, hollow inside, and develops longitudinally according to a longitudinal axis Z.
The section of the segment 10 (
The segment 10 (
The segment 10 according to the present invention is defined, starting from the first end 12 and in succession along the longitudinal axis Z, by at least a first end portion 21, a second intermediate portion 22 and a third end portion 23 made in a single body.
The first end portion 21 (
The third end portion 23 also comprises, adjacent to the second intermediate zone 22, a substantially rectilinear tract 43.
The first end 12 is substantially fork shaped, and the first segment 15 is introduced through it.
The first 26 and second bushings 27 are recessed in the two sides of the fork.
The first segment 15 pivots in the first bushings 26 by means of a pin, while two opposite brackets 29, only one of which is visible in
The brackets 29 are provided with three pivoting holes 30 in each of which the segment 10, the end of the piston 131 of an actuation member 31 and a second connection staff, not visible in the drawings, respectively pivot.
The second connection bracket in turn pivots on the first segment 15, and provides to articulate the segment 10 and the first segment 15 with respect to each other.
The actuation member 31, in this case a hydraulic actuator, pivots with the end of its cylinder 231 in correspondence with the second intermediate portion 22 of the segment 10.
The second intermediate portion 22, or attachment portion of the actuation member 31, has a height H of the cross section that varies along the longitudinal axis Z, to define a zone protruding with respect to the intrados surface 19 of the segment 10.
More specifically, on the intrados side of the segment 10, the second intermediate portion 22 has a first side 33 facing toward the first end 12 and a second side 34 inclined and converging toward the first side 33 to define together a vertex 35, which is advantageously rounded or with a rounded connection.
In correspondence with the first side 33 a through cavity 36 is made, configured to allow an end portion of the actuation member 31 to be inserted through it.
In the second intermediate portion 22 third pivoting bushings 39 are integrated, in which the other end of the actuation member 31 is pivoted.
The third bushings 39 are integrated in the second intermediate portion 22 of the segment in an external position with respect to the intrados surface 19, so as to allow connection of the actuation member 31.
The first side 33 (
The second side 34 is inclined with respect to the rectilinear tract 43 connecting to the second end 13 by a second angle of inclination β comprised between 5° and 25°, preferably between 10° and 20°, even more preferably by about 15° again with respect to the longitudinal axis Z.
The second angle of inclination β is in any case less than the first angle α, thus ensuring a gentler connection between the protruding zone and the second end 13, which is the end opposite the one where the actuation member 31 articulates.
In particular, the inclination of the second side 34 is a good compromise between the mechanical resistance properties required for the sections in that tract and the need to reduce the overall bulk so as to allow the overall reduction of the articulated arm 11 in its closed configuration.
A very reduced amplitude of the second angle of inclination β, although advantageous with regard to the reduction in intensification of tensions, would not allow the compact closure of the articulated arm 11. To this must also be added a greater quantity of material with consequent increase of the overall weight.
The first side 33 (
The second side 34, on the contrary, connects to the third end portion 23, and in particular to its rectilinear tract 43, with a second filleted tract 41 having a second rounding radius R2.
The third bushings 39 are distanced by a determinate axial distance X and by a determinate transverse distance Y with respect to the interaxis of the second bushings 27. The ratio between the axial distance X and the transverse distance Y is comprised between 3.9 and 15.6, preferably between 4.5 and 12, even more preferably between 6 and 10.
The pivoting axis of the second bushings 27 is displaced vertically, toward the intrados and with respect to the longitudinal axis Z, by a determinate gap G, comprised between 0.01 and 0.2 times the height H.
This allows to use second bushings 27 with an optimized diameter so as to suitably distribute uniformly the pressures that are generated when the actuation member 31 is driven.
The second side 34 and the second filleted tract 41 develop overall for a determinate first longitudinal length E of the second portion 22.
According to one feature of the invention, the ratio between the second rounding radius R2 and the first length E is comprised between 1.8 and 7.2, preferably more than 3.5. This ratio allows to optimize the mechanical resistance of the cross sections and the sizes of the segment 10, obtaining similar advantages with respect to what we described before for the second angle of inclination β.
The first side 33 and the first filleted tract 40 develop overall for a determinate second longitudinal length S of the second intermediate portion 22.
In order to reduce the quantity of material required to make the segment 10 in said zone, and to prevent the actuation member 31 from remaining contained inside the segment 10, it is advantageous to provide that the ratio between the second length S and the axial distance X is comprised between 0.15 and 0.65, preferably between 0.25 and 0.55, even more preferably between 0.30 and 0.50.
The first bushings 26 are offset axially by a distance P with respect to the second bushings 27. The distance P is about 0.8-1.2 times the height H of the cross section of the first end portion 21. This allows to contain the overall length of the first end portion 21, preventing useless waste of material.
In some advantageous forms of embodiment, it is provided that the second intermediate portion 22 has a particular disposition of the fibers of which it consists, different from that of the first end portion 21 and of the third end portion 23, in order to confer on this portion greater resistance to stress.
It is clear that modifications and/or additions of parts may be made to the segment as described heretofore, without departing from the field and scope of the present invention.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of segment, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.
| Number | Date | Country | Kind |
|---|---|---|---|
| MI2012A000206 | Feb 2012 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB13/00186 | 2/14/2013 | WO | 00 |
