A machine for bending metal rods with a variable length support table

Abstract: Machine for bending metallic bars, comprising at least one bending unit (9), comprising a structure (10) equipped with a foldaway extension table (20), formed by a rolling blind shaped and guided structure, presenting a variable length upper branch (20) forming said extension table, on the resting table level of the bending unit (9), and a lower branch (21), which is parallel and distanced from the upper branch.

Description: This invention relates to a machine for bending metallic bars according to the preamble of claim 1, specifically bars for reinforced concrete, of the type comprising at least one bending unit, comprising a structure with an upper bar resting table, on which a vertical axis bending plate is rotationally mounted, the plate carrying an offset axial pin for bending the bars, said structure being mobily mounted on a table holding the bars to be bent. This invention can be applied both to simple bar bending machines or systems, and to cutting and bending systems. Machines for the type described above have been known and used for some time. One of such machines is, for example, described and illustrated in European Patent EP-B-0648577 by the Applicant. Typically, these machines employ two bending units of the type specified above, which are substantially identical and which simultaneously and symmetrically move either approaching or distancing a central mount, according to the length of the bar to be bent, as well as the position of the bar section which must be bent. It must be noticed that, in any case, despite reference is often made in this description to a machine of this type, i.e. a machine with two bending units, this invention can be applied to any different type of machine, also with a single bending unit. In the case illustrated in the aforesaid European Patent, the two bending units are operated in two different phases of a bar bending cycle after positioning them in different areas of the bar, to confer the required shape to the bar. In each machining cycle phase, the bars rest centrally on said central mount, as well as on the bending plates of the two bending units, in areas which are distanced from the central portion of the bar. Machines of the aforesaid type, however, present a drawback. When the two bending units are moved to two reciprocally relatively close positions and, consequently, are close two said central mount, the two extreme portions of the bar project for a considerable length from the two bending units and tend to flex downwards by effect of gravity. In this condition, the metallic bars tend to assume an arched condition, which entails the risk of lifting a section of the bar, which is on each bending unit, with the consequent release of the bar from the offset pin, which is used for the bending operation and the risk of possible interference of the end of the bar with the machine parts during bending. Naturally, to prevent this drawback, in principle, each bending unit could be simply equipped with a rigid overhanging resting table, projecting in the direction of the respective end of the runway, which would prevent the downward flexion of the terminal part of each bar projecting from the respective bending unit. This solution, however, is not practicable when a bending unit is positioned near one end of its runway, because in its case a rigid overhanging table of this kind would project over the end of the runway and would interfere with the other machine elements and with surrounding apparatuses, entailing considerable additional dimensions. A similar drawback would occur also in the case of a machine using a single bending unit. The objective of this invention is to prevent these drawbacks, providing a bending machine, which avoids the risk of arching of the bars to be bent positioned on the bending unit, or bending units, also when the terminal part of the bars projects for a considerable length from the bending unit. In order to attain this purpose, this invention relates to a machine of the type illustrated at the beginning of this description, characterised in that the structure of the bending unit is equipped with a foldaway extension table on one side, formed by a rolling blind shaped and guided structure, presenting a variable length upper branch, on the resting table level of the bending apparatus, and a lower branch, which is parallel and distanced from the upper branch. As mentioned above, this invention can be applied both to system employing several bending units and to machines with a single bending unit. In a preferred form of embodiment, said rolling blind structure consists of a plurality of reciprocally jointed strips, with end shoes, slidingly mounted in parallel rails, which define a semicircular return course of said upper branch to said lower branch. Thanks to the aforesaid characteristics, when the bending unit is near one end of the runway, the upper branch of the rolling blind structure is reduced to a minimum length and does not obstruct in any way reaching said position by the bending unit. Conversely, when the bending unit is distanced from this extreme position, in which the bars present terminal positions which length considerably projects over the bending unit, the upper branch of the rolling blind structure covers the entire distance between the bending unit and the end of the runway and forms a resting table for the bars, preventing downwards flexion of the terminal portions of the bars and the consequent drawbacks described above. This invention will be better explained by the following detailed descriptions with reference to the accompanying figure as non-limiting example, whereas: figure 1 is a perspective schematic view of a form of embodiment of the machine according to this invention, figure 2 is a lateral elevated view of the end of the machine seen from the part where the bar cutting head is located, figure 3 is a cross-section view of the machine part shown in figure 2, and figure 4 is blow-up of a part in figure 3. With reference to the drawings, numeral 1 generally indicates a machine destined to cut circular cross-section metallic bars for reinforced concrete in several sections of predetermined length which are then subjected to one or more subsequent bending operations to assume the final required shape. As mentioned several times, the case of application of this invention in a double bending unit system is described as a non-limiting example. It is however understood that this invention can be applied in general to any type of machine, also with a single bending unit. According to a known technique, the machine 1 comprises an elongated table 2, including a channel 3 along which one or more metallic bars 5 of standard length are advanced, destined to be cut into sections of predetermined length. A head 4 is arranged on one end of the table 2, comprising, according to known practice, a plurality of counter-rotating roller pairs for feeding the bars 4 along the channel of the table 2. Again according to the known technique, the head 4 advances the bars 5 until the head end of the bars comes into contact with the stop (not shown), which position is adjustable. Having reached this position, a hydraulic cylinder 6 is operated to lower a blade 7, which cuts the bar to obtain a section of bar of predetermined length on the bench 2. A machine of this type is also described and illustrated in a co-pending Patent Application by the Applicant, with reference to new and advantageous perfection of the structure of the head 4, of the control criteria of the stop means for the head ends of the bars to be cut and of the cutting blade control cylinder. After cutting, the bar sections thus obtained on the table 2 (usually the machine works on a bundle of bars at the same time) are unloaded from the side of the cutting table and collected on an apparatus destined to perform one or more subsequent bending operations of the bars. The bending apparatus comprises a central mount 8 (fixed in the case of the example shown), destined to receive and support the central portion of the bars to be bent. Furthermore, the bending apparatus comprises two bending units 9, also of the known type, each comprising a mobile structure 10 in the longitudinal direction A of the bench and with an upper table 11, on which a bending plate 12 is rotationally mounted with an offset pin 13, destined to bend the bars. The structure of each bending unit 9 and the conveying means of each unit along a runway arranged in the longitudinal direction A of the table are not described and illustrated in detail, being well known by technical experts of the sector. For this purpose, reference can be made, for example, to previous European Patents EP-B-0648577 and EP-B-0835702 by the Applicant. The elimination of such details from these drawings is aimed at making the latter more readily and simply comprehensible. According to the conventional technique, the two bending units 9 move simultaneously and symmetrically either approaching or distancing the central mount 8. As mentioned, the central portion of the bars are received over the fixed, central mount 8, which is conveniently equipped with a bar fastening clamp, and rest on two bending plates 12 in unit 9. These plates are turned to bend the respective sections of the bars by offset pins 13, around the central pins of the plates 12. As mentioned above, when the two bending units 9 are arranged in a reciprocally close position, the end portions of the bars considerably project over the apparatus 9. To prevent downwards flexion of the terminal projecting portions of the bar, which would make the central portions of the bar arch upwards with the possible risk of being released upwards with respect to the offset bending pins 13, this invention includes two auxiliary resting tables associated to the two bending units 9. As concerns the unit 9 which is most distant from the cutting head 4 (i.e. the one of the right in figure 1), the auxiliary resting table simply consists of a table 15 rigidly connected to the bending apparatus structure and overhanging from the structure, ensuring a suitable support to the part of the bars which projects over said bending apparatus (naturally, the invention described below can be applied also to the unit 9 which is most distant from the head 4). Conversely, an auxiliary resting table rigidly connected to the unit 9 and overhanging from the unit cannot be adopted on the bending unit 9 which is closer to the cutting head 4 (i.e. the one on the left in figure 1), since this table would interfere with the head 16 of the machine and would prevent positioning the aforesaid bending unit 9 next to the head 16. In order to solve this drawback, the machine according to this invention presents a foldaway extension table on the side of the last mentioned unit 9 facing the head 16. The foldaway extension table 20 consists of a rolling blind shaped and guided structure, presenting a variable length upper branch forming said table 20, and a lower return branch 21, which is parallel and distanced under the upper branch 20. As clearly visible in figures 2, 3, said structure consists of a plurality of strips 22 reciprocally jointed together by means of two side chains 23 with shoes 24 guided in two parallel rails 25 mounted on the fixed structure of the machine. The rails 25 describe a semicircular course on a vertical plane, which is parallel to the direction A, with a centre positions on an axis 26, which is perpendicular to said vertical plane. Thanks to the structure described above, when said unit 9 is in its extreme position, which is closest to the head 16 of the machine (figure 1), the upper branch of said rolling blind structure, forming the resting table 20, presents its minimum length. From this position, the unit 9 can be approached to the central mount 8 (see figure 1). One end of the rolling blind structure is rigidly connected to the aforesaid bending unit structure 9, for which, in said movement, the unit drags the rolling blind structure, which upper branch 20 is consequently extended, while the return portion underneath is shortened. Obviously, the structure is arranged so that, when the bending unit 9 reaches its extreme position closest to the central mount 8, the opposite end 25 of the rolling blind structure is still engaged at least partially within the guides 25. As clearly appears in the description above, the machine according to this invention prevents the drawback of a downwards flexion of the terminal portions of the bars to be bent which projects over the bending apparatuses, also on the side of the machine which is closest to the cutting head, where a rigid auxiliary resting table cannot be arranged, because it would obstruct the positioning of the bending unit in the extreme position closest to the machine head. Naturally, the rolling blind structure described above can be applied in general to any type of machine, also presenting a single cutting unit, with or without cutting device. Furthermore, also the assembly drawings of rolling blind structure and the guides for its movement can be considerably varied with respect to the description provided herein, within the scope of the appended claims. An additional preferred characteristic of the machine according to this invention consists of the arrangement of a unloading table of the bent bars, on a side of the bending unit or bending units, and can be moved from a horizontal position, in which it supports the bent ends of the bars and a slanted position forming an unloading chute for the bent bars. Numeral 50 refers to this table in figure 1, where it is shown in its slanted position.

Claims: Machine for bending metallic bars, comprising at least one bending unit (9), comprising a structure (10) with an upper resting table (11), on which a vertical axis bending plate (12) is rotationally mounted, the plate carrying an offset axial pin (13) for bending the bars, said structure (10) being mobily mounted on a table holding the bars (5) to be bent, characterised in that said structure (10) of the bending unit (9) is equipped with a foldaway extension table (20) on one side, formed by a rolling blind shaped and guided structure, presenting a variable length upper branch forming said extension table (20), on the resting table (11) level of the bending apparatus, and a lower branch (21), which is parallel and distanced from the upper branch. Bending machine according to claim 1, characterised in that said rolling blind structure consists of a plurality of reciprocally jointed strips (22), with ends slidingly in two rails (25) arranged on parallel vertical planes in the longitudinal direction (A) of the machine table and each defining a course including a semicircular section with a centre on an axis (26), which is perpendicular to said table, the strip structure having one end connected to the structure (10) of the bending unit (9) and the opposite end free. Bending machine according to claim 2, characterised in that the strips forming said rolling blind structure are reciprocally connected, at each end, by means of a respective transmission chain. Bending machine according to claim 1, in which two bending units (9) move simultaneously and symmetrically to approach and distance a central mount (8), characterised in that said foldaway extension table is associated with that of the two aforesaid units (9), which is closest to a cutting head (4) belonging to the machine. Bending machine according to claim 4, characterised in that the bending unit (9) most distant from the cutting head (4) of the machine is equipped with a fixed extension table, rigidly connected to the structure of said unit and overhanging from the unit. Bending machine according to claim 1, characterised in that it comprises an unloading table of the bent bars located on one side of the bending unit, or units, and which can move between a horizontal position, in which it supports the bent ends of the bars, and a slanted position, to form a bent bar unloading chute.

Inventors: PERUZZO LORENZO, PERUZZO, LORENZO
Applicants: OSCAM SPA, OSCAM S.P.A.
Application year: 2001
Main classification: B21D11
IPC codes: B21D7, B21D11