EP2029297A1

EP2029297A1 - Bending machine for bars, particularly bars fed from a roll, and relative method

Info

Publication number: EP2029297A1
Application number: EP07729905A
Authority: EP
Inventors: Giorgio Del Fabro
Original assignee: MEP Macchine Elettroniche Piegatrici SpA
Current assignee: MEP Macchine Elettroniche Piegatrici SpA
Priority date: 2006-06-08
Filing date: 2007-06-05
Publication date: 2009-03-04
Also published as: BRPI0711489A2; RU2008151432A; ITUD20060147A1; RU2433879C2; WO2007141273A1

Abstract

Bending machine (10) and method for shaping metal bars (11) fed from a roll (12). The machine (10) comprises a bending assembly (13) for the metal bars (11), a shearing assembly (14) disposed upstream of the bending assembly (13) to shear the metal bars (11) to size, a first drawing assembly (15) disposed upstream of the shearing assembly (14) to unroll the metal bars (11) from the roll (12) and feed them to the bending assembly (13), and a second drawing assembly (16) disposed between the shearing assembly (14) and the first drawing assembly (15) and provided with gripper members (21, 22, 121, 122). The second drawing assembly (16) comprises selective clamping/unclamping members (23, 123), which intervene on the gripper members (21, 22, 121, 122), to selectively configure the second drawing assembly (16) between a first uninfluential operating condition, in which the gripper members (21, 22, 121, 122) do not interfere with the advance of the metal bars (11), and a second active operating condition, in which the gripper members (21, 22, 121, 122) intervene on the terminal segments of the roll (12) no longer gripped in the first drawing assembly (15) and feed the bending assembly (13).

Description

"BENDING MACHINE FOR BARS, PARTICULARLY BARS FED FROM A

ROLL, AND RELATIVE METHOD"

* * * * *

FIELD OF THE INVENTION The present invention concerns a bending machine for metal bars, particularly for metal bars fed from a roll or coil, and sheared on each occasion according to the shape and size, that is, the linear development, of the shaped article to be made. In particular, the bending machine according to the invention includes at least an auxiliary drawing assembly able to move, possibly forward and backward, the terminal segments or tail ends of the roll, so as to be able to make the bends on said terminal segments with greater ease and accuracy, and/or to discharge segments or working scrap from the machine.

EP-Al-1.535.675 describes the features of the preamble of the main claims 1 and 10. BACKGROUND OF THE INVENTION

Bending machines for bars are known, suitable to produce shaped reinforcement elements, such as for example stirrups, which machines essentially consist of at least a bending assembly, a shears and a drawing assembly, disposed upstream of the shears in order to pick up the bars to be bent from a store and feed them to the bending machine.

Known bending machines can have a second drawing assembly disposed downstream of the bending assembly, which is used to move the bar linearly with respect to the bending assembly, so as to perform tail-end bends in order to make the shaped piece. The drawing assemblies can be of the type with rollers, grippers or a combination of rollers and grippers.

It is also known that, in specific bending machines for pre-cut metal bars, or segments of bars, an auxiliary drawing assembly is used, disposed immediately upstream of the shears which in turn is located upstream of the bending assembly.

The auxiliary drawing assembly remains substantially always gripping on the pre-cut bar being worked, mainly so as to allow, when the article is complete, to discharge the working scraps or surpluses from the machine, and so as to assist the drawing assembly downstream of the bending machine in feeding the terminal segment of the bars when the so-called tail-end bends are being made.

However, if this last type of known bending machine is fed with metal bars coming from a roll, the known auxiliary drawing assembly, which remains always gripping the bar being worked, can cause loops to be formed in the segment comprised between itself and the other drawing assembly upstream of the shears, with a consequent blockage of the bending machine, interruption of production, and need for a specialized intervention of extraordinary maintenance.

Purpose of the present invention is therefore to achieve a bending machine for bars fed from a roll and provided with an auxiliary drawing assembly disposed immediately upstream of the shears, which does not have the functional disadvantages of the state of the art.

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.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea. In accordance with the above purpose, the bending machine according to the present invention is applied for shaping metal bars fed from a roll and comprises at least an assembly to bend the bars, at least a shearing assembly disposed upstream of the bending assembly and able to shear to size the bars fed from the roll, a first drawing assembly disposed upstream of the shearing assembly and able to unroll the bars from the roll in order to feed them to the bending assembly, and at least a second auxiliary drawing assembly disposed upstream of the shearing assembly and downstream of the first drawing assembly, and able to feed the terminal part of the roll, for example when it is nearly finished, and possibly discharge the working scrap in order to finish the completed article. According to a characteristic feature of the present invention, the second drawing assembly comprises, associated therewith, selective clamping/unclamping means, able to intervene suitably on the gripper members of the drawing assembly, in order to determine at least a first substantially uninfluential operating condition, in which the gripper members do not interfere with the advance of the metal bars fed by the first drawing assembly, so as to allow them to advance freely through the second drawing assembly, and a second active operating condition, in which the gripper members interfere with the advance of the metal bars and determine the feed thereof towards the bending assembly.

According to the invention, the second active operating condition is assumed in particular when the roll that feeds the bars is nearing the end, that is, when the segment of bar that is formed after shearing is no longer gripped by the first drawing assembly, and the residual segment has to be discharged from the machine.

This condition, moreover, can also be assumed when it is desired to make small shaped pieces, for example when the last side is shorter than the distance between the first drawing assembly and the bending assembly. Advantageously, until a condition is detected in which there is a bar gripped by the first drawing assembly, the gripper members of the second drawing assembly remain in the first uninfluential operating condition, so as to prevent accidental, non-synchronized feed of the two drawing assemblies, causing the formation of loops with consequent blockages. At the moment the terminal end of the last bar obtainable from the roll is released by the first drawing assembly, the selective clamping/unclamping means take the gripper members of the second drawing assembly to their second active operating condition, causing the last segment of the roll to be fed to the bending assembly. With the bending machine according to the present invention it is thus possible to selectively constrain or release the grip of the second drawing assembly on the metal bars fed, according to the operating state of the first drawing assembly and/or the length of the bars, thus avoiding the risk of loops or other deformations forming between the two drawing assemblies. This advantage allows to reduce accidental interruptions to the machine, thus increasing the productivity thereof, and also reducing the frequency and costs of extraordinary maintenance.

According to a variant, the selective clamping/unclamping means comprises one or more actuators able to keep the gripper members, for example two or more rollers, selectively distanced and separated from the metal bars in transit, according to the operating condition provided.

The selective clamping/unclamping means, according to another variant, comprises a clutch member which selectively makes the rollers idle, so as to define the first uninfluential operating condition.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some preferential forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- figs 1 and 2 show schematically a view from above of a bending machine according to the invention in two different operating steps;

- fig. 3 shows an enlarged detail of the machine according to the invention in the operating position in fig. 1 ; - fig. 4 shows a section from A to A in fig. 3 in the operating condition in fig. 1 ;

- fig. 5 shows a section from A to A in fig. 3 in the operating condition in fig. 2;

- fig. 6 shows an enlarged detail of a variant of the machine according to the invention;

- fig. 7 shows a lateral view of the detail in fig. 6 in the operating condition of fig. 1;

- fig. 8 shows a lateral view of the detail in fig. 6 in the operating condition of fig. 2. DETAILED DESCRIPTION OF SOME PREFERENTIAL FORMS OF

EMBODIMENT With reference to the attached drawings, a bending machine 10 according to the present invention is applied to make shaped reinforcement articles for the building sector, starting from metal bars 1 1 fed directly from a roll 12 or coil. In this case, two metal bars 11 arriving from two different rolls 12 are fed simultaneously to the bending machine 10, but it cannot be excluded that the bending machine 10 can also be fed by a single metal bar 1 1 or by three or more metal bars 11 simultaneously.

The bending machine 10 according to the invention essentially comprises a bending assembly 13, a shears 14 located upstream of the bending assembly 13, a first drawing assembly 15 with pairs of rollers 19, located upstream of the shears 14, and a second drawing assembly, or auxiliary drawing assembly 16, disposed immediately upstream of the shears 14 and downstream of the first drawing assembly 15. In this case, the bending machine 10 also comprises a third drawing assembly

17 disposed downstream of the bending assembly 13 and able to translate the metal bars 1 1 in a bending step, called tail-end bending, of their terminal segment.

The second drawing assembly 16 comprises a plurality of rollers 20, of which at least one is driven, indicated in its entirety by the reference number 21, and at least a gripper roller 22, opposite the driven roller 21 with respect to the metal bars 11, and selectively cooperating with the driven roller 21 to draw the metal bars 11. In this case, the driven roller 21 is keyed to a shaft of an oil-dynamic motor 24. In particular, the gripper roller 22 is mobile with respect to the driven roller 21, and is associated with a clamping/unclamping device 23 which, as will be explained hereafter in detail, allows to selectively configure the gripper roller 22 between a first operating condition, in which it has substantially no effect on the drawing of the metal bars 11 and allows the free advance thereof through the second drawing assembly 16; and a second operating condition, in which it actively participates in the drawing of the metal bars 11, and allows to feed to the bending assembly 13 the terminal parts, or tail ends, of the roll 12 from which the metal bars 1 1 are obtained, when the latter are no longer gripped in the first drawing assembly 15, or allows said terminal parts to be discharged from the machine.

Each gripper roller 22 is normally cushioned by means of a helical spring 25, associated in known manner with the rotation shaft 29 of the gripper roller 22, so as to render the latter elastically pivoting and to absorb possible imperfections and vibrations of the metal bars 11. Due to the effect of the pressure exerted by the helical spring 25, facing downwards in the attached drawings, the relative gripper roller 22 normally remains in contact with the driven roller 21 , at a determinate inactive pressure, and in any case not interfering with the drawing, which determinate pressure is easily contrasted by the metal bars 11 in transit.

In this thrust condition of the helical spring 25, the gripper roller 22 is not able to keep the metal bars 11 adherent to the driven roller 21 and hence the second drawing assembly 16 does not perform any action on the metal bars 11, which on the contrary advance substantially freely through it, and functions only as a guide.

In this case, the clamping/unclamping device 23 consists substantially of an oil-dynamic actuator 26 disposed above and coaxial with the helical spring 25, so that, by means of a metal block 27 associated therewith, it determines the selective axial compression of the helical spring 25. This compression determines an increase in the contact pressure between the gripper roller 22 and the driven roller 21, so that the metal bars 1 1 in transit between them are gripped substantially between the two rollers 21 and 22, and therefore are actively subjected to the drawing action imparted by the second drawing assembly 16. The bending machine according to the present invention functions as follows.

In a normal condition of feed of the bending assembly 13 (fig. 1), the metal bars 11 are removed, substantially continuously, from the respectively rolls 12 and made to translate axially towards the bending assembly 13, by means of the action of the first drawing assembly 15. In this condition the second drawing assembly 16 remains in its uninfluential operating condition (fig. 4), in which it does not participate in the drawing of the metal bars 1 1 and functions substantially as a guide and cushion.

At the moment the tail-ends of the metal bars 11 pass beyond the first drawing assembly 15 (fig. 2), the oil-dynamic actuator exerts said axial pressure on the helical spring 25 by means of the metal block 27, in such a manner that the metal bars 11 in transit in the second drawing assembly are substantially gripped between the two rollers 21 and 22 (fig. 5).

In this way, the rotation imparted by the oil-dynamic motor 24 to the driven roller 21 determines the axial drawing of the metal bars 11 towards the bending assembly 13.

According to the form of embodiment shown in figs. 6 to 8, the second drawing assembly 16 comprises, apart from the rollers 20, at least a driven roller, indicated in its entirety by the reference number 121, and at least a contrasting roller 122, opposite the driven roller 121 with respect to the metal bars 11, and selectively cooperating with the driven roller 121 to draw the metal bars 11. In this case, the driven roller 121 is keyed to a shaft of an oil-dynamic motor 124 which is mounted in turn on a metal slider 127. In particular, the driven roller 121 is movable with respect to the contrasting roller 122, and is associated with a clamping/unclamping device 123 which, as will be explained in detail hereafter, allows the selective configuration of the driven roller 121 between a first operating condition, in which it does not interfere with the metal bars 11 and allows the free advance thereof through the second drawing assembly 16, and a second operating condition, in which it acts on the metal bars 11 and actively participates in their drawing. In this way, the driven roller 121 allows to feed to the bending assembly 13 also the terminal parts or tail ends of the roll 12 from which the metal bars 11 are obtained, when the latter are no longer gripped in the first drawing assembly 15, or allows them to be discharged from the machine.

Each contrasting roller 122 is associated axially with an encoder 125, or other type of position transducer, which allows the metric counting of the metal bars 1 1 fed, and sends relative signals to a command and control unit of the machine 10, in order to optimize the management of the switching on/off of the motors provided.

In this case, the clamping/unclamping device 123 comprises an oil-dynamic actuator 126 disposed above and connected to the metal slider 127, so as to determine the selective vertical movement thereof.

The vertical movement of the metal slider 127 determines the movement of the oil-dynamic motor 124, and consequently of the driven roller 121, with respect to the contrasting roller 122, until contact with the metal bars 1 1. In this condition, the metal bars 1 1 in transit are gripped between the two rollers 121 and 122, and therefore are subject to the drawing action imparted by the second drawing assembly 16. The drawing action can be imparted either to feed short segments of bar 1 1 to the bending assembly, in order to make small pieces, or to discharge from the machine 10.

It is clear, however, that modifications and/or additions of parts or steps may be made to the bending machine 10 and relative method as described heretofore, without departing from the scope of the present invention.

For example, it comes within the scope of the present invention to provide that, instead of the oil-dynamic actuator 26, the clamping/unclamping device 23 can comprise a clutch able to selectively release the rotation of the driven roller 21 with respect to the relative oil-dynamic motor 24, and hence define the two conditions, respectively, the uninfluential condition, by making the driven roller 21 idle, and the active drawing condition, by making the driven roller 21 draw.

It also comes within the scope of the present invention to provide that the clamping/unclamping device includes movement members, associated respectively with the rollers 21 and 22, in order to reciprocally distance the latter from each other and from the axis of feed of the metal bars 1 1.

It is also clear that, although the present invention has been described with reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of bending machine for bars, particularly bars fed from a roll, and the relative method, having the characteristics as set forth in the claims and hence all coming within the scope of protection defined thereby.

Claims

1. Bending machine for shaping metal bars (11) fed from a roll (12), said machine comprising at least a bending assembly (13) for said metal bars (11), a shearing assembly (14) disposed upstream of said bending assembly (13) and able to shear said metal bars ( 1 1) to size, a first drawing assembly (15) disposed upstream of said shearing assembly (14) and able to unroll said metal bars (1 1) from said roll (12) in order to feed them to said bending assembly (13), and a second drawing assembly (16) disposed between said shearing assembly (14) and said first drawing assembly (15) and provided with gripper members (21, 22, 121, 122), characterized in that said second drawing assembly (16) comprises selective clamping/unclamping means (23, 123), able to intervene on said gripper members (21, 22, 121, 122), in order to selectively configure said second drawing assembly (16) between at least a first operating condition, in which said gripper members (21, 22, 121, 122) do not interfere with the advance of said metal bars (11), and a second active operating condition, in which said gripper members (21, 22, 121, 122) intervene on the terminal segments of the roll (12) when said terminal segments are no longer gripped in the first drawing assembly (15).

2. Machine as in claim 1, characterized in that said selective clamping/unclamping means (23, 123) comprises at least an actuator member

(26, 126) associated with at least one of said gripper members (21, 22, 121, 122), and able to move it with respect to the other said gripper members (21, 22, 121, 122), in order to selectively define said first operating condition and said second active operating condition.

3. Machine as in claim 1 or 2, characterized in that said gripper members comprise at least a driven roller (21, 121), and at least a gripper or contrasting roller (22, 122) opposite said driven roller (21, 121), with respect to said metal bars (1 1), and selectively cooperating with said driven roller (21, 121) so as to selectively draw said metal bars (11).

4. Machine as in claim 3, characterized in that said gripper roller (22) is mobile with respect to said driven roller (21), and is associated with said selective clamping/unclamping means (23).

5. Machine as in claim 3, characterized in that said driven roller (121) is movable with respect to said contrasting roller (122), and is associated with said selective clamping/unclamping means (123).

6. Machine as in claim 3 or 4, wherein said gripper roller (22) is associated with at least a cushion element (25), characterized in that said actuator member (26) is disposed above said cushion element (25), so as to determine the selective compression of said cushion element (25) and consequently an increase in the contact pressure between said gripper roller (22) and said driven roller (21, 121) in said second active operating condition.

7. Machine as in claim 1, characterized in that said selective clamping/unclamping means (23, 123) comprises at least a clutch member associated with at least one of said gripper members (21, 22, 121, 122), and able to make it selectively idle so as to define said first uninfluential operating condition or said second active operating condition.

8. Machine as in any claim hereinbefore, characterized in that it also comprises a third drawing assembly (17) disposed downstream of said bending assembly (13).

9. Machine as in claim 3, characterized in that said contrasting roller (122) is associated with an encoder (125), or other type of position transducer, which allows the metrical counting of the metal bars (11) in transit.

10. Method for shaping metal bars (1 1) fed from a roll (12), by means of a bending machine comprising at least a bending assembly (13) for said metal bars

(11), a shearing assembly (14) disposed upstream of said bending assembly (13) to shear said metal bars (11) to size, a first drawing assembly (15) disposed upstream of said shearing assembly (14) in order to unroll said metal bars (11) from said roll (12) and feed them to said bending assembly (13), and a second drawing assembly (16) disposed between said shearing assembly (14) and said first drawing assembly (15) and provided with gripper members (21, 22, 121, 122), characterized in that it comprises at least a first step in which said metal bars (11) are gripped in the first drawing assembly (15) and said second drawing assembly (16) is configured in a first operating condition, in which said gripper members (21, 22, 121, 122) do not interfere with the advance of said metal bars (11), and a second step in which said metal bars (11) are no longer gripped in the first drawing assembly (15) and said second drawing assembly (16) is configured in an active operating condition, in which said gripper members (21 , 22, 121 , 122) intervene on the terminal segments of the roll (12) and feed said bending assembly (13) or discharge said terminal segments from the machine.

11. Method as in claim 10, characterized in that it comprises at least a step of metric counting of the metal bars (11) in transit, performed by a contrasting roller (122) associated with an encoder (125) or other type of position transducer, of said second drawing assembly (16).